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An experimental study of excited state level populations in the argon inductively coupled plasma Walker, Zane Harry 1986

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EXPERIMENTAL STUDY OF EXCITED STATE LEVEL POPULATIONS IN THE ARGON INDUCTIVELY COUPLED PLASMA By ZANE HARRY WALKER B . S c , Dalhousie U n i v e r s i t y , 1983 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES ( Department of Chemistry ) We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA June 1986 © Zane Harry Walker I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e h e a d o f my d e p a r t m e n t o r by h i s o r h e r r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f Chemistry  The U n i v e r s i t y o f B r i t i s h C o l u m b i a 1956 Main Ma l l V a n c o u v e r , Canada V6T 1Y3 D ate June 11, 1986 E-6 (3/81) ABSTRACT In an e f f o r t t o e l u c i d a t e e x c i t a t i o n and i o n i z a t i o n of a n a l y t e i n t h e i n d u c t i v e l y c o u p l e d p l a s m a , e x c i t e d s t a t e l e v e l p o p u l a t i o n s have been d e t e r m i n e d f o r t h r e e a n a l y t e s , F e , Ba, and C r , from e x p e r i m e n t a l l y measured l i n e e m i s s i o n i n t e n s i t i e s a t v a r i o u s r f i n p u t powers and s p a t i a l p o s i t i o n s . Measurement of l i n e i n t e n s i t i e s was a c h i e v e d u s i n g a 4096 p i x e l l i n e a r p h o t o d i o d e a r r a y s p e c t r o m e t e r . The p h o t o d i o d e a r r a y s p e c t r o m e t e r p r o v e d t o be v e r y a d v a n t a g e o u s i n t h e c o l l e c t i o n of d a t a , a l l o w i n g t h e s i m u l t a n e o u s measurement of l i n e i n t e n s i t i e s from a w a v e l e n g t h window a p p r o x i m a t e l y 50 nm i n w i d t h . P o p u l a t i o n p l o t s were c o n s t r u c t e d from r e l a t i v e l e v e l p o p u l a t i o n s f o r b o t h atom and i o n s p e c i e s o f t h e t h r e e a n a l y t e s and t h e i r d e p endence on r f i n p u t power was e x a m i n e d . The s p a t i a l d e p e ndence of t h e F e l and F e l l p o p u l a t i o n s was a l s o s t u d i e d . E x c i t a t i o n t e m p e r a t u r e s d e t e r m i n e d from t h e atom and i o n l e v e l p o p u l a t i o n s of F e , Ba and Cr were e x a m i n e d . The r e s u l t s s t r o n g l y s u p p o r t t h e e x i s t e n c e of p a r t i a l l o c a l t hermodynamic e q u i l i b r i u m i n t h e ICP. S uch an e q u i l i b r i u m c o n d i t i o n i s c h a r a c t e r i z e d by an o v e r p o p u l a t i o n of low e n e r g y atom l e v e l s and t h e p r e s e n c e of Saha e q u i l i b r i u m between h i g h e n e r g y atom l e v e l s and t h e g r o u n d s t a t e i o n . The p r i n c i p a l means of a n a l y t e e x c i t a t i o n and i o n i z a t i o n a p p e a r s t o be a r e s u l t of i n e l a s t i c e l e c t r o n c o l l i s i o n s . i i TABLE OF CONTENTS C h a p t e r Page 1 . I n t r o d u c t i o n 1.1 Ob j e c t i ve 1 1.2 The ICP: An H i s t o r i c a l P e r s p e c t i v e 2 1 . 3 The ICP. . 4 1.4 A n a l y t e E x c i t a t i o n and I o n i z a t i o n 8 1.4.1 C o l l i s i o n a l E x c i t a t i o n and D e - e x c i t a t i o n By E l e c t r o n s 9 1.4.2 C o l l i s i o n a l I o n i z a t i o n and T h r e e Body R e c o m b i n a t i o n 10 1.4.3 R a d i a t i v e R e c o m b i n a t i o n 10 1.4.4 R a d i a t i v e D e - e x c i t a t i o n 11 1.4.5 P e n n i n g I o n i z a t i o n 12 1.4.6 Asymmetric C h a r g e T r a n s f e r W i t h A r g o n 12 1.5 Thermodynamic E q u i l i b r i u m i n t h e ICP 13 1.5.1 M a x w e l l D i s t r i b u t i o n 14 1.5.2 B o l t z m a n n D i s t r i b u t i o n 15 1.5.3 Saha D i s t r i b u t i o n 16 1.5.4 Guldberg-Waage D i s t r i b u t i o n 18 1.5.5 Summary 19 1.6 E x c i t e d S t a t e L e v e l P o p u l a t i o n s 20 2. E x p e r i m e n t a l 2.1 I n s t r u m e n t a t i o n 22 i i i 2.2 Computer I n t e r f a c i n g of LPDA and Data A c q u i s i t i o n 30 2.3 S o f t w a r e 36 2.4 Sample P r e p a r a t i o n and S e l e c t i o n of A n a l y t e C o n c e n t r a t i o n 37 2.5 S e l e c t i o n of S p e c t r a l L i n e s 38 2.6 Measurement of S p a t i a l l y R e s o l v e d L i n e I n t e n s i t i e s 38 2.7 S p e c t r a l C o r r e c t i o n of S p e c t r a l L i n e I n t e n s i t i e s 40 3. E x c i t e d S t a t e L e v e l P o p u l a t i o n s 3.1 I n t r o d u c i t o n 41 3.2 R e s u l t s 49 3.3 Fe R e s u l t s 54 3.3.1 Fe L e v e l P o p u l a t i o n s a t 8 mm Above the L o a d C o i l 54 3.3.2 Fe L e v e l P o p u l a t i o n s a t 16 mm Above t h e L o a d C o i l 65 3.3.3 Fe E x c i t e d S t a t e L e v e l P o p u l a t i o n s 72 3.4 Ba R e s u l t s 77 3.4.1 Ba E x c i t e d S t a t e L e v e l P o p u l a t i o n s 77 3.5 Cr R e s u l t s 81 3.5.1 Cr E x c i t e d S t a t e L e v e l P o p u l a t i o n s 82 3.6 D i s c u s s i o n 90 4 . Summary 100 R e f e r e n c e s 104 A p p e n d i x A 109 i v A p p e n d i x B A p p e n d i x C A p p e n d i x D L I S T OF TABLES T a b l e D e s c r i p t i o n Page I . LTE t e m p e r a t u r e s c o r r e s p o n d i n g t o measured e l e c t r o n d e n s i t i e s 53 I I . E m i s s i o n l i n e s of Fe i n c l u d i n g w a v e l e n g t h , gA v a l u e s , and e x c i t a t i o n e n e r g i e s 55 I I I . E m i s s i o n l i n e s o f Ba i n c l u d i n g w a v e l e n g t h , gA v a l u e s , and e x c i t a t i o n e n e g i e s 78 IV. E m i s s i o n l i n e s o f Cr i n c l u d i n g w a v e l e n g t h , gA v a l u e s , and e x c i t a t i o n e n e r g i e s 83 V. C r I and C r I I e x c i t a t i o n t e m p e r a t u r e s and LTE t e m p e r a t u r e s a t 0.75 kW, 1.00 kW, 1.25 kW, 1.50 kW and 1.75 kW r f i n p u t power 91 V I . Fe, Ba and Cr e x c i t a t i o n t e m p e r a t u r e s a t 1.25 kW and 1.75 kW r f i n p u t power 95 v i L I S T OF FIGURES F i g u r e D e s c r i p t i o n Page 1. The ICP d i s c h a r g e 6 2. B l o c k d i a g r a m of i n s t r u m e n t a t i o n 23 3. The ICP t o r c h 24 4. The c o n c e n t r i c g l a s s n e b u l i z e r 25 5. The ICP t o r c h , s p r a y chamber and c o n c e n t r i c g l a s s n e b u l i z e r 26 6. P l o t o f r e f r a c t i v e i n d e x of f u s e d s i l i c a v e r s u s w a v e l e n g t h 29 7. Imaging d i s t a n c e of a f u s e d s i l i c a l e n s , w i t h a r a d i u s of c u r v a t u r e of 69.80 nm, as a f u n c t i o n of w a v e l e n g t h 31 8. D i a g r a m o f t h e i n t e r f a c i n g between t h e LPDA and th e CompuPro m i c r o c o m p u t e r v i a t h e t r a n s i e n t r e c o r d e r 33 9. T i m i n g d i a g r a m f o r t h e a c q u i s i t i o n o f d a t a from t h e LPDA . 34 10. T i m i n g d i a g r a m f o r t h e r e a d o u t of d a t a from t h e t r a n s i e n t r e c o r d e r 35 11a. A p l o t o f the l o g a r i t h m o f F e l e x c i t e d s t a t e l e v e l p o p u l a t i o n s vs e x c i t a t i o n e n e r g y , from d a t a e x t r a c t e d from F a i r e s , Palmer and Engleman [ 5 3 ] . P o p u l a t i o n s have been f i t t e d t o a s e c o n d o r d e r v i i F i g u r e D e s c r i p t i o n Page p o l y n o m i a l 48 11b. A p l o t of t h e l o g a r i t h m of F e l e x c i t e d s t a t e l e v e l p o p u l a t i o n s vs e x c i t a t i o n e n e r g y , from d a t a e x t r a c t e d from F a i r e s , Palmer and Engleman [ 5 3 ] . P o p u l a t i o n s have been f i t t e d u s i n g l i n e a r r e g r e s s i o n 48 12. A S a h a - B o l t z m a n n LTE p l o t of t h e l o g a r i t h m of l e v e l p o p u l a t i o n s as a f u n c t i o n of e n e r g y . E + and E + + a r e t h e i o n i z a t i o n e n e r g i e s o f a t o m i c and i o n i c s p e c i e s r e s p e c t i v e l y . The l e v e l p o p u l a t i o n s a r e r e p r e s e n t e d by a s i n g l e t e m p e r a t u r e g i v e n by t h e s l o p e o f t h e S a h a - B o l t z m a n n l i n e s (-1/kT) 50 13. A p l o t o f t h e l o g a r i t h m of F e l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 8 mm above t h e l o a d c o i l and a t 1.25 kW r f i n p u t power as a f u n c t i o n of e n e r g y . R a d i a l p o s i t i o n s o f 0 mm and 1.5 mm 58 14. F e l l e v e l d e p e n d e n t t e m p e r a t u r e s c a l c u l a t e d from F e l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 8 mm above t h e l o a d c o i l , a t an r f i n p u t power of 1.25 kW and a t a r a d i a l p o s i t i o n of 0 mm 59 15. A p l o t o f t h e l o g a r i t h m of F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 8 mm above t h e l o a d c o i l and a t 1.25 kW r f i n p u t power a s a f u n c t i o n of e n e r g y . R a d i a l v i i i F i g u r e D e s c r i p t i o n Page p o s i t i o n s of 0 mm and 1.5 mm 61 16. A p l o t of t h e l o g a r i t h m of F e l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 8 mm above t h e l o a d c o i l and a t 1.75 kW r f i n p u t power as a" f u n c t i o n o f e n e r g y . R a d i a l p o s i t i o n s of 0 mm and 1.5 mm 63 17. A p l o t of t h e l o g a r i t h m of F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 8 mm above t h e l o a d c o i l and a t 1.75 kW r f i n p u t power as a f u n c t i o n of e n e r g y . R a d i a l p o s i t i o n s of 0 mm and 1.5 mm 64 18. A p l o t of t h e l o g a r i t h m of F e l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l and a t 1.25 kW r f i n p u t power as a f u n c t i o n of e n e r g y . R a d i a l p o s i t i o n s of 0 mm and 1.5 mm 66 19 . A p l o t of t h e l o g a r i t h m o f F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l and a t 1.25 kW r f i n p u t power as a f u n c t i o n o f e n e r g y . R a d i a l p o s i t i o n s of 0 mm and 1.5 mm 67 20. F e l l e v e l d e pendent t e m p e r a t u r e s c a l c u l a t e d from F e l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t an r f i n p u t power of 1.25 kW and a t a r a d i a l p o s i t i o n of 0 mm 68 21. A p l o t of t h e l o g a r i t h m o f F e l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l and a t 1.75 i x F i g u r e D e s c r i p t i o n Page kW r f i n p u t power as a f u n c t i o n of e n e r g y . R a d i a l p o s i t i o n s of 0 mm and 1.5 mm 70 22. A p l o t of t h e l o g a r i t h m of F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l and a t 1.75 kW r f i n p u t power as a f u n c t i o n of e n e r g y . R a d i a l p o s i t i o n s of 0 mm and 1.5 mm 71 23. A p l o t of t h e l o g a r i t h m of F e l and F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 8 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power of 1.25 kW. The s o l i d l i n e s r e p r e s e n t s LTE c a l c u l a t e d p o p u l a t i o n s 73 24. A p l o t of t h e l o g a r i t h m of F e l and F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 8 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power o f 1.75 kW. The s o l i d l i n e s r e p r e s e n t s LTE c a l c u l a t e d p o p u l a t i o n s 74 25. A p l o t of t h e l o g a r i t h m of F e l and F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power o f 1.25 kW. The s o l i d l i n e s r e p r e s e n t s LTE c a l c u l a t e d p o p u l a t i o n s 75 26. A p l o t of t h e l o g a r i t h m of F e l and F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , x F i g u r e D e s c r i p t i o n Page at a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power o f 1.75 kW. The s o l i d l i n e s r e p r e s e n t s LTE c a l c u l a t e d p o p u l a t i o n s 76 27. A p l o t of t h e l o g a r i t h m of B a l and B a l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power o f 1.25 kW. The s o l i d l i n e s r e p r e s e n t s LTE c a l c u l a t e d p o p u l a t i o n s 79 28. A . p l o t of t h e l o g a r i t h m of B a l and B a l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power o f 1.75 kW. The s o l i d l i n e s r e p r e s e n t s LTE c a l c u l a t e d p o p u l a t i o n s 80 29. A p l o t of t h e l o g a r i t h m of C r I and C r I I l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power o f 0.75 kW. The s o l i d l i n e s r e p r e s e n t s LTE c a l c u l a t e d p o p u l a t i o n s 85 30. A p l o t of t h e l o g a r i t h m of C r I and C r I I l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power o f 1.00 kW. The s o l i d l i n e s r e p r e s e n t s LTE c a l c u l a t e d p o p u l a t i o n s 86 x i F i g u r e D e s c r i p t i o n Pag 31. A p l o t of t h e l o g a r i t h m o f C r I and C r I I l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power of 1.25 kW. The s o l i d l i n e s r e p r e s e n t s LTE c a l c u l a t e d p o p u l a t i o n s 32. A p l o t of t h e l o g a r i t h m o f C r I and C r I I l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power of 1.50 kW. The s o l i d l i n e s r e p r e s e n t s LTE c a l c u l a t e d p o p u l a t i o n s 33. A p l o t of t h e l o g a r i t h m o f C r I and C r I I l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power of 1.75 kW. The s o l i d l i n e s r e p r e s e n t s LTE c a l c u l a t e d p o p u l a t i o n s 34. C a l c u l a t e d M a x w e l l i a n d i s t r i b u t i o n of e l e c t r o n e n e r g i e s b a s e d on an e q u i l i b r i u m t e m p e r a t u r e of 8000 K ACKNOWLEDGEMENT I would l i k e to express my s i n c e r e thanks to Dr. Michael W. Blades for h i s sound guidance and i n v a l u a b l e suggestions which he c o n t r i b u t e d throughout the course of my r e s e a r c h . It i s a l s o important to acknowledge the c o n t r i b u t i o n s made by other members of our re s e a r c h group in the form of c o n s t r u c t i v e c r i t i c i s m and b e n e f i c i a l d i s c u s s i o n s . I would a l s o l i k e to thank the s t a f f of the machine shop and the e l e c t r o n i c shop f o r t h e i r help in the development of much of the i n s t r u m e n t a t i o n . x i i i The improvement of t h e u n d e r s t a n d i n g i s f o r two e n d s : f i r s t , f o r our own i n c r e a s e of knowledge; s e c o n d l y , t o e n a b l e us t o d e l i v e r and make out t h a t knowledge t o o t h e r s . John L o c k e x i v In l o v i n g memory of my g r a n d p a r e n t s ; J o s e p h and L a u r a A n d e r s o n , and H a r r y and M y r t l e W a l k e r . xv C h a p t e r 1 INTRODUCTION 1.1 OBJECTIVE The i n d u c t i v e l y coupled plasma ( ICP ) has become a v a l u a b l e and r e l i a b l e atomic emission source f o r q u a l i t a t i v e and q u a n t i t a t i v e elemental a n a l y s i s s i n c e the e a r l y 1970's. I t has seen a p p l i c a t i o n i n the a n a l y s i s of g e o l o g i c a l , b i o l o g i c a l , i n d u s t r i a l and environmental samples. There i s l i t t l e doubt that the ICP has l i v e d up to or even exceeded the e x p e c t a t i o n of i t s e a r l y u s e r s . The e a r l y success of the ICP as an a n a l y t i c a l t o o l has not been p a r a l l e l e d by an e a r l y understanding of a n a l y t e e x c i t a t i o n and i o n i z a t i o n mechanisms. A number of r e s e a r c h e r s have compared e x p e r i m e n t a l l y measured q u a n t i t i e s , such as ion-atom emission i n t e n s i t y r a t i o s , e x c i t a t i o n temperatures and e l e c t r o n d e n s i t i e s , with those p r e d i c t e d using a l o c a l thermodynamic e q u i l i b r i u m ( LTE ) model. In doing so, s e v e r a l anomalies have been observed i n c l u d i n g lower than expected a n a l y t e ion-atom i n t e n s i t y r a t i o s [1] and disagreement between e l e c t r o n temperatures, i o n i z a t i o n temperatures and e x c i t a t i o n temperatures [2,3,4] which, under LTE, should a l l be equal. In order to e x p l a i n these anomalies, s e v e r a l models were suggested, such as the argon-metastable model [5] , r a d i a t i v e t r a p p i n g model [ 6 ] , the r e a c t i o n model [7] and the 1 a m b i p o l o r d i f f u s i o n model [ 8 ] , In an e f f o r t t o u n d e r s t a n d some of t h e s e a n o m a l i e s i n v o l v i n g a n a l y t e e x c i t a t i o n and i o n i z a t i o n i n t h e ICP, a s t u d y b a s e d on e x c i t e d s t a t e l e v e l p o p u l a t i o n s of t h r e e a n a l y t e s , Fe, Ba and C r , was u n d e r t a k e n . T h i s t h e s i s w i l l p r e s e n t t h e r e s u l t s of t h i s s t u d y and w i l l d i s c u s s t h e s e r e s u l t s i n terms of p o s s i b l e a n a l y t e e x c i t a t i o n and i o n i z a t i o n p r o c e s s e s . 1.2 THE ICP : AN HISTORICAL PERSPECTIVE The f i r s t m e n t i o n of an i n d u c t i v e l y c o u p l e d plasma i n t h e l i t e r a t u r e was i n 1947 by Babat who d e s c r i b e d t h e o p e r a t i o n of a l o w - p r e s s u r e d i s c h a r g e [ 9 ] , V e r y l i t t l e work was done on f u r t h e r d e v e l o p i n g t h e ICP u n t i l 1961 when Reed d e s c r i b e d t h e o p e r a t i o n of an a t m o s p h e r i c p r e s s u r e p l a s m a u s i n g a r g o n as w e l l as m i x t u r e s of a r g o n and e i t h e r h e l i u m , h y d r o g e n or oxygen [ 1 0 ] . The f i r s t a p p l i c a t i o n of an a t m o s p h e r i c ICP was- not f o r s p e c t r o s c o p i c s t u d i e s , but r a t h e r i n t h e g r o w t h of s i n g l e c r y s t a l s of r e f r a c t o r y o x i d e s [ 1 0 , 1 1 ] , The a u t h o r d i d however r e c o g n i z e t h a t t h e ICP would f i n d a p p l i c a t i o n s w h e r e v e r dc p l a s m a s were u s e d , s u c h as i n t h e measurement of a t o m i c t r a n s i t i o n p r o b a b i l i t i e s . The f i r s t r e p o r t o f an ICP b e i n g u s e d a s a s p e c t r o s c o p i c e m i s s i o n s o u r c e was p u b l i s h e d i n 1964 by G r e e n f i e l d , J o n e s and B e r r y [ 1 2 ] . The t o r c h d e s i g n u s e d was s i m i l a r t o t h e one us e d by Reed [10] and c o n s i s t e d of two c o n c e n t r i c q u a r t z t u b e s open a t 2 one end, w i t h t h e gas e n t e r i n g t a n g e n t i a l l y a t t h e o t h e r end. A number of d i s t i n c t a d v a n t a g e s of t h e ICP o v e r e x i s t i n g c o n v e n t i o n a l a t o m i c e m i s s i o n s o u r c e s s u c h as a r c s and s p a r k s were o b s e r v e d . These a d v a n t a g e s i n c l u d e d t h e l a c k of e l e c t r o d e s w h i c h gave f r e e d o m from c o n t a m i n a t i o n , and t h e e x t r e m e l y weak s p e c t r a l b a c k g r o u n d p r o d u c e d by t h e s o u r c e . A p p r o x i m a t e l y one y e a r l a t e r , Wendt and F a s s e l p u b l i s h e d a s t u d y on t h e a p p l i c a t i o n of t h e ICP as a s p e c t r o m e t r i c e x c i t a t i o n s o u r c e [ 1 3 ] . U n l i k e t h e t y p e of t o r c h u s e d p r e v i o u s l y by Reed and by G r e e n f i e l d e t a l . w h i c h employed t a n g e n t i a l gas f l o w w i t h i n t h e t o r c h , Wendt and F a s s e l o p t e d t o e x p e r i m e n t w i t h l a m i n a r gas f l o w s . The o r i g i n a l c l a i m was t h a t t h e l a m i n a r - f l o w ICP p r o d u c e d a more s t a b l e a n a l y t i c a l e n v i r o n m e n t t h a n one p r o d u c e d u s i n g t h e t a n g e n t i a l - f l o w ICP. However, b e c a u s e of t h e l a m i n a r f l o w o f gas e n t e r i n g t h e t o r c h , t h e sample t e n d e d t o f l o w a r o u n d r a t h e r t h a n t h r o u g h t h e p l a s m a . T h i s l e d t o s e v e r e i n t e r f e r e n c e s [ 1 4 ] , a p p a r e n t l y due t o f l u c t u a t i o n s i n t h e e l e c t r i c a l p r o p e r t i e s of t h e d i s c h a r g e [ 1 5 ] . One of t h e f i r s t major s t u d i e s p u b l i s h e d on t h e ICP w h i c h c l e a r l y d e m o n s t r a t e d t h e p r a c t i c a l i t y of s u c h a s y s t e m as an a n a l y t i c a l t o o l a p p e a r e d i n 1968 a u t h o r e d by D i c k e n s e n and F a s s e l [ 1 6 ] , D e t e c t i o n l i m i t s f o r a number of e l e m e n t s were d e t e r m i n e d and c l e a r l y showed i t s c o m p e t i t i v e n e s s w i t h o t h e r s p e c t r o s c o p i c t e c h n i q u e s . However, i t was n o t u n t i l f o u r y e a r s l a t e r t h a t t h e f i r s t s u c c e s s f u l c o m m e r c i a l ICP a t o m i c e m i s s i o n s p e c t r o s c o p y 3 ( ICP-AES ) i n s t r u m e n t was m a r k e t e d . ICP-AES i s used t o d a y t o a n a l y s e a wide range of s a m p l e s . T y p e s of samples i n c l u d e g e o l o g i c a l [ 1 7 , 1 8 ] , i n d u s t r i a l [ 1 9 ] , b i o l o g i c a l [ 2 0 , 2 1 , 2 2 ] , a g r i c u l t u r a l [ 2 3 ] , and e n v i r o n m e n t a l [ 2 4 ] . In r e c e n t y e a r s ICP-AES has been u s e d as a m u l t i - e l e m e n t - s p e c i f i c d e t e c t o r f o r h i g h p r e s s u r e l i q u i d c h r o m a t o g r a p h y [ 2 5 ] . The ICP has been u s e d as an a t o m / i o n s o u r c e f o r a t o m i c f l u o r e s c e n c e s p e c t r o s c o p y [26] and has a l s o been i n c o r p o r a t e d as an i o n s o u r c e i n t o t h e d e v e l o p m e n t of p l a s m a s o u r c e mass s p e c t r o m e t r y [ 2 7 ] . O n l y a b r i e f o u t l i n e of t h e d e v e l o p m e n t of t h e ICP has been p r e s e n t e d h e r e . F o r a d d i t i o n a l i n f o r m a t i o n on t h e t o p i c , a number of l i t e r a t u r e r e v i e w s have been p u b l i s h e d [ 2 8 , 2 9 , 3 0 , 3 1 ] . 1.3 THE ICP A l t h o u g h p l a s m a i s t h e f o u r t h s t a t e of m a t t e r and t h e most abundant i n t h e u n i v e r s e , i t i s c e r t a i n l y t h e l e a s t e n c o u n t e r e d on e a r t h . The d e f i n i t i o n o f a p l a s m a p r o v i d e d by W e b s t e r ' s D i c t i o n a r y i s an i o n i z e d gas ( as i n t h e a t m o s p h e r e s of s t a r s ) c o n t a i n i n g a b o u t e q u a l numbers of p o s i t i v e i o n s and e l e c t r o n s and d i f f e r i n g from an o r d i n a r y gas i n b e i n g a good c o n d u c t o r o f e l e c t r i c i t y and i n b e i n g a f f e c t e d by a m a g n e t i c f i e l d [ 3 2 ] . 4 Such a d e f i n i t i o n , a l t h o u g h c o r r e c t , d i s p a r a g e s t h e c o m p l e x i t y of p l a s m a s . The p r o b l e m of c o n t a i n i n g p l a s m a m a t t e r , w h i c h has a t e m p e r a t u r e of a t l e a s t s e v e r a l t h o u s a n d d e g r e e s , was overcome w i t h t h e d e v e l o p m e n t o f t h e ICP t o r c h [ 1 0 ] . I t i s t h e r e f o r e l o g i c a l t o b e g i n a d i s c u s s i o n of t h e ICP by f i r s t d i s c u s s i n g t h e t o r c h . A d i a g r a m of a c o n v e n t i o n a l t o r c h i s p r o v i d e d i n f i g u r e 1. The t o r c h c o n s i s t s of two c o n c e n t r i c q u a r t z t u b e s , w i t h a t h i r d , s m a l l e r a e r o s o l t u b e , p l a c e d on t h e c e n t e r a x i s . T h r e e a r g o n gas f l o w s e n t e r t h e t o r c h : two of them, t h e p l a s m a and a u x i l i a r y f l o w , e n t e r t a n g e n t i a l l y ; and t h e t h i r d , t h e a e r o s o l f l o w , e n t e r s from t h e base of t h e t o r c h . The r o l e of t h e a u x i l i a r y f l o w i s t o p r e v e n t t h e p l a s m a from coming i n c o n t a c t w i t h t h e t o p of t h e a e r o s o l t u b e . The a e r o s o l f l o w i s u s e d t o c a r r y t h e sample, u s u a l l y i n t h e f o r m of an a e r o s o l s p r a y , i n t o t h e p l a s m a v i a t h e a e r o s o l t u b e . The t o r c h i s p l a c e d s u c h t h a t t h e t o p of t h e i n n e r c o n c e n t r i c q u a r t z t u b e l i e s 3 or 4 mm below t h e f i r s t of t h e t h r e e t u r n s of a w a t e r - c o o l e d c o p p e r t u b e w h i c h c o m p r i s e s t h e l o a d c o i l . The a r g o n atoms e n t e r i n g n e a r t h e base o f t h e t o r c h b e g i n a t a n g e n t i a l m o t i o n upwards. At some p o i n t i n t i m e , t h e i n c o m i n g a r g o n gas i s s e e d e d w i t h e l e c t r o n s t h r o u g h t h e use of a t e s l a c o i l . A h i g h r a d i o f r e q u e n c y ( r . f . ) s i g n a l i s p a s s e d t h r o u g h the l o a d c o i l p r o d u c i n g an a l t e r n a t i n g m a g n e t i c f i e l d . As t h e a r g o n gas s e e d e d w i t h e l e c t r o n s e n t e r s t h e a l t e r n a t i n g m a g n e t i c 5 Q u a r t z Tubes A n a l y t e E m i s s i o n A r g o n Plasma A n a l y t e C h a n n e l L o a d C o i l M a g n e t i c F i e l d RF Power ( 1-3 kW, 27 MHz ) P l a s m a Gas ( 12 1pm ) A u x i l i a r y Gas ( 0 - 0 . 4 1pm ) Sample A e r o s o l ( < 1 1pm ) F i g u r e 1. The ICP d i s c h a r g e . 6 f i e l d , t h e k i n e t i c e n e r g y of t h e e l e c t r o n s i s g r e a t l y i n c r e a s e d . The number of c o l l i s i o n s between e l e c t r o n s and a r g o n atoms i n c r e a s e s r e s u l t i n g i n t h e f o r m a t i o n of more e l e c t r o n s and a r g o n i o n s Ar + e * A r + + 2e ( 1 ) As t h e e l e c t r o n number d e n s i t y i n c r e a s e s t h e r e v e r s e p r o c e s s t o ( 1 ) , t h r e e body r e c o m b i n a t i o n , i s o b s e r v e d A r + + 2e *• Ar + e . (2) A s e c o n d p o s s i b l e p r o c e s s l e a d i n g t o a d e c r e a s e i n a r g o n i o n p o p u l a t i o n i s two body r e c o m b i n a t i o n + - * Ar + e *• Ar + hv . (3) * In t h i s p r o c e s s , Ar r e p r e s e n t s an e x c i t e d s t a t e o f an a r g o n atom and t h e e x c e s s e n e r g y o f t h e p r o c e s s i s c a r r i e d away i n t h e form of e l e c t r o m a g n e t i c r a d i a t i o n , hv. Once t h e s e e l e c t r o n p r o d u c i n g and e l e c t r o n c o n s u m i n g p r o c e s s e s r e a c h s t e a d y s t a t e t h e p l a s m a i s s u s t a i n e d , a s s u m i n g th e r . f . s i g n a l b e i n g p a s s e d t h r o u g h t h e l o a d c o i l r e m a i n s u n i n t e r r u p t e d . I t i s i m p o r t a n t t o n o t e t h a t t h e s o u r c e of e n e r g y needed t o s u s t a i n t h e p l a s m a does n o t a r i s e from t h e b r e a k i n g of c h e m i c a l bonds, as i s t h e c a s e i n f l a m e s , but 7 r a t h e r from a t r a n s f e r o f t h e e n e r g y a p p l i e d t o t h e l o a d c o i l i n t h e form of r . f . power. I t i s a l s o w o r t h s t r e s s i n g t h e i m p o r t a n c e of t h e t a n g e n t i a l m o t i o n of a r g o n gas up t h r o u g h the t o r c h . T h i s m o t i o n l e a d s t o t h e f o l l o w i n g c o n d i t i o n s : (1) v o r t e x s t a b i l i z a t i o n , w h i c h i s a p p a r e n t by t h e e x t e n s i o n of t h e p l a s m a f u r t h e r " u p s t r e a m " above t h e l o a d c o i l r e g i o n and (2) t h e c e n t e r i n g of t h e p l a s m a w h i c h p r e v e n t s c o n t a c t w i t h t h e w a l l s of t h e t o r c h and a i d s i n c o o l i n g t h e t o r c h [ 1 0 ] . T h e r e a r e a number o f methods f o r i n t r o d u c i n g a sample i n t o t h e p l a s m a , t h e most common of w h i c h i s t o p a s s a sample i n t h e form of an aqueous ( or o r g a n i c ) s o l u t i o n t h r o u g h a n e b u l i z e r f o r m i n g an a e r o s o l g a s . However i t i s a l s o p o s s i b l e t o i n t r o d u c e powdered samples [33,34] and s o l i d s a m p l e s [35,36,37] u s i n g t h e a p p r o p r i a t e t e c h n i q u e s . The a e r o s o l gas punches a h o l e t h r o u g h t h e base of t h e p l a s m a r e s u l t i n g i n t h e f o r m a t i o n of an a n a l y t e c h a n n e l ( see f i g u r e 1 ). The f u r t h e r t h e sample t r a v e l s up t h e a n a l y t e c h a n n e l , t h e g r e a t e r i s i t s r a d i a l d i f f u s i o n . A change i n t h e a e r o s o l f l o w r a t e w i l l change t h e amount of sample e n t e r i n g t h e p l a s m a and w i l l a l t e r t h e c h a r a c t e r i s t i c s of t h e a n a l y t e c h a n n e l . 1.4 ANALYTE EXCITATION AND IONIZATION I f a sample i s i n t r o d u c e d i n t o t h e b a s e of t h e p l a s m a i n t h e 8 form of an aqueous a e r o s o l g a s , t h e sample w i l l f i r s t undergo a p r o c e s s of d e s o l v a t i o n , t h e n v a p o u r i z a t i o n and f i n a l l y d i s s o c i a t i o n upon w h i c h a t o m i c s p e c i e s a r e f ormed. T h e s e a n a l y t e atoms can i n t e r a c t t h r o u g h e l a s t i c and i n e l a s t i c c o l l i s i o n s w i t h b o t h f r e e e l e c t r o n s and v a r i o u s a r g o n s p e c i e s p r e s e n t i n t h e p l a s m a . In e l a s t i c c o l l i s i o n s , t h e t o t a l k i n e t i c e n e r g y of t h e c o l l i d i n g p a r t i c l e s i s c o n s e r v e d and no change i n t h e i n t e r n a l e n e r g i e s o f t h e i n d i v i d u a l p a r t i c l e s i s o b s e r v e d . Of more i n t e r e s t t o t h e s p e c t r o s c o p i s t a r e t h e i n e l a s t i c c o l l i s i o n s w h i c h r e s u l t i n c h a n g e s i n t h e i n t e r n a l e n e r g i e s of t h e p a r t i c l e s as t h e y a r e e x c i t e d t o h i g h e r e n e r g y - S t a t e s . The f o l l o w i n g s e c t i o n s d e s c r i b e what a r e b e l i e v e d t o be t h e p r i n c i p a l p r o c e s s e s l e a d i n g t o e x c i t a t i o n and i o n i z a t i o n of a n a l y t e i n t h e ICP [ 3 8 ] . T h e r e a r e , however, o t h e r p o s s i b l e p r o c e s s e s w h i c h may make minor c o n t r i b u t i o n s t o t h e e x c i t a t i o n and i o n i z a t i o n of a n a l y t e [ 7 ] , 1.4.1 COLLISIONAL EXCITATION AND DE-EXCITATION BY ELECTRONS An a n a l y t e atom, X, or i o n , X + , may be e x c i t e d t o a h i g h e r e n e r g y l e v e l t h r o u g h a c o l l i s i o n w i t h an e l e c t r o n X + e" « ».X* + e~ (4) X + e * » X + e . (5) 9 In t h e f o r w a r d p r o c e s s , l o s t k i n e t i c e n e r g y of t h e e l e c t r o n i s t r a n s f e r r e d t o t h e i n t e r n a l e n e r g y of t h e a n a l y t e . The atom X, ( or i o n X + ) may be i n i t s g r o u n d s t a t e , or i n an e x c i t e d s t a t e * +* which' i s l o w e r i n e n e r g y than X ( or X ) . In t h e r e v e r s e p r o c e s s , i n t e r n a l e n e r g y w h i c h i s l o s t t h r o u g h d e - e x c i t a t i o n i s t r a n s f e r r e d t o t h e e l e c t r o n i n t h e form of k i n e t i c e n e r g y . 1.4.2 COLLISIONAL IONIZATION AND THREE BODY RECOMBINATION I f t h e e n e r g y o f t h e c o l l i d i n g e l e c t r o n i s s u f f i c i e n t , i o n i z a t i o n of t h e a n a l y t e i s p o s s i b l e X + e~ « »-X + + e~ + e~ . (6) The a n a l y t e atom X may be i n i t s g r o u n d s t a t e o r i n one of i t s e x c i t e d s t a t e s . The r e s u l t i n g i o n , X + , formed i n t h i s r e a c t i o n may a l s o be i n an e x c i t e d s t a t e , a l t h o u g h i t i s more l i k e l y t o be f o u n d i n i t s g r o u n d s t a t e . In t h e r e v e r s e p r o c e s s e x c i t e d s t a t e atoms c a n be formed t h r o u g h t h r e e body r e c o m b i n a t i o n . 1.4.3 RADIATIVE RECOMBINATION I t i s a l s o p o s s i b l e t o o b s e r v e r e c o m b i n a t i o n p r o c e s s e s i n w h i c h t h e e x c e s s e n e r g y r e s u l t i n g f r o m a c o l l i s i o n i s c a r r i e d away i n t h e form of e l e c t r o m a g n e t i c r a d i a t i o n 10 X + + e * X* + hv c o n t (7) The p r o d u c t s r e s u l t i n g from t h i s c o l l i s i o n a r e e x c i t e d s t a t e * atoms, X , and a c o n t i n u u m p h o t o n ( h " c o n t ) whose e n e r g y , , i s g i v e n by E, = E + ( E + + E. hv e X 1 E x * > (8) where, E E X * E X + = e n e r g y of t h e e l e c t r o n = e x c i t a t i o n e n e r g y of t h e atom = e x c i t a t i o n e n e r g y o f i o n = i o n i z a t i o n p o t e n t i a l of a n a l y t e X. 1 . 4 . 4 R A D I A T I V E D E - E X C I T A T I O N The most s i g n i f i c a n t p r o c e s s i n terms of t h e a n a l y t i c a l c a p a b i l i t i e s o f t h e ICP i s r a d i a t i v e d e - e x c i t a t i o n of e x c i t e d s t a t e atoms and i o n s X x + hi/, . p l i n e X + + hi/, • p l i n e ( 9 ) ( 1 0 ) The e n e r g y of t h e p h o t o n e m i t t e d i s d i r e c t l y r e l a t e d t o t h e e n e r g y d i f f e r e n c e between t h e upper s t a t e q and t h e l o w e r s t a t e 1 1 p. B e c a u s e e a c h e l e m e n t has a u n i q u e a t o m i c s t r u c t u r e , the r e s u l t i n g a t o m i c s p e c t r u m , t h a t i s t h e c o l l e c t i o n of p h o t o n s ( hv nne ) o v e r a l l e n e r g i e s , i s a l s o u n i q u e . Thus i t i s p o s s i b l e t o q u a l i t a t i v e l y a n a l y s e an unknown sample f o r i t s e l e m e n t a l c o m p o s i t i o n . 1.4.5 PENNING IONIZATION AND EXCITATION I t i s p o s s i b l e t o e n c o u n t e r a n a l y t e e x c i t a t i o n and i o n i z a t i o n r e s u l t i n g from c o l l i s i o n s w i t h m e t a s t a b l e a r g o n atoms X + Ar • X + + Ar + e (11) m The e x c e s s e n e r g y i n t h i s p r o c e s s i s c a r r i e d away by t h e e l e c t r o n i n t h e f o r m of k i n e t i c e n e r g y . The i m p o r t a n c e of P e n n i n g i o n i z a t i o n and e x c i t a t i o n has been c o n t r o v e r s i a l , b e i n g s u p p o r t e d by some [39,40] and d i s c a r d e d by o t h e r s [ 3 8 , 7 ] . 1.4.6 ASYMMETRIC CHARGE TRANSFER WITH ARGON E x c i t a t i o n of an a n a l y t e atom i s p o s s i b l e t h r o u g h c h a r g e t r a n s f e r w i t h an a r g o n i o n A r + + X »-Ar + X + + A E . (12) 1 2 The l i k e l i h o o d of t h i s p r o c e s s o c c u r i n g i s g r e a t e r when t h e e n e r g y d e f e c t , A E , i s s m a l l . T h i s e x c e s s e n e r g y i s s i m p l y c a r r i e d away i n t h e k i n e t i c e n e r g y of t h e two c o l l i d i n g p a r t i c l e s . 1.5 THERMODYNAMIC EQUILIBRIUM IN THE ICP In t h e p r e c e e d i n g s e c t i o n , a number of e l e m e n t a r y p r o c e s s e s p r e s e n t i n t h e p l a s m a were o u t l i n e d . I t i s now p o s s i b l e t o m a t h e m a t i c a l l y d e s c r i b e t h e d i s t r i b u t i o n of s t a t e s p r o d u c e d i n t h e s e p r o c e s s e s and r e l a t e t h e s e d i s t r i b u t i o n s t o a common p a r a m e t e r T, t e m p e r a t u r e . Under c o n d i t i o n s of d e t a i l e d b a l a n c i n g t h e p r o d u c t i o n of e a c h e l e m e n t a r y s t a t e ( or f o r w a r d p r o c e s s ) i s e x a c t l y b a l a n c e d by i t s d e s t r u c t i v e ( or r e v e r s e ) p r o c e s s . ' Such a c o n d i t i o n l e a d s t o a s t a t e of thermodynamic e q u i l i b r i u m ( TE ). However, i n an e m i s s i o n s o u r c e s u c h a s t h e ICP, TE i s n o t a c h i e v e d due t o t h e p r e s e n c e of h i g h c o n c e n t r a t i o n and t e m p e r a t u r e g r a d i e n t s and t h e l o s s of e n e r g y from t h e pla s m a b o u n d a r y t h r o u g h r a d i a t i v e p r o c e s s e s ( 7 , 9 , 1 0 ) . The a b s o r p t i o n o f t h i s r a d i a t i o n i s u n f a v o u r a b l e b e c a u s e of t h e r e l a t i v e l y s m a l l c r o s s s e c t i o n s f o r the i n t e r a c t i o n of r a d i a t i o n w i t h m a t t e r and t h e low o p t i c a l d e n s i t y of t h e ICP. Thus t h e te r m l o c a l thermodynamic e q u i l i b r i u m ( LTE ) i s i n t r o d u c e d t o d e s c r i b e t h e e q u i l i b r i u m t h a t e x i s t s l o c a l l y f o r a l l d i s t r i b u t i o n s e x c e p t f o r t h e 1 3 d i s t r i b u t i o n of r a d i a t i o n . To put i t s i m p l y , under LTE one u n i q u e t e m p e r a t u r e can be u s e d t o s a t i s f y t h e M a x w e l l d i s t r i b u t i o n of p a r t i c l e v e l o c i t i e s , t h e B o l t z m a n n d i s t r i b u t i o n of l e v e l p o p u l a t i o n s , the Saha d i s t r i b u t i o n of atoms and i o n s of a g i v e n s p e c i e s , and t h e Guldberg-Waage d i s t r i b u t i o n of m o l e c u l a r spec i e s . The f o l l o w i n g d i s t r i b u t i o n f u n c t i o n s a r e w e l l e s t a b l i s h e d and w i d e l y a c c e p t e d ; hence d e t a i l e d d e r i v a t i o n s of t h e s e e q u a t i o n s a r e beyond t h e s c o p e of t h i s t h e s i s and have been o m i t t e d . 1.5.1 MAXWELL DISTRIBUTION M a x w e l l ' s e q u a t i o n d e s c r i b e s t h e v e l o c i t y ( o r e n e r g y ) d i s t r i b u t i o n of p a r t i c l e s i n v o l v e d i n e l a s t i c c o l l i s i o n s by f ( V ) dV = ( m/27TkT ) 3 / / 2 exp ( -mv 2/2kT ) 47rv 2 dV (13) g g where, f ( V ) d V = p r o b a b i l i t y t h a t a p a r t i c l e has a v e l o c i t y i n t h e r e g i o n V and V + dV = t h e mass of t h e p a r t i c l e = gas k i n e t i c t e m p e r a t u r e of t h e p a r t i c l e = B o l t z m a n n ' s c o n s t a n t . m T g P e r h a p s a more m e a n i n g f u l f o rm of e q u a t i o n (13) i n t h e c o n t e x t of 1 4 t h i s t h e s i s i s o b t a i n e d by u s i n g t h e e x p r e s s i o n r e l a t i n g k i n e t i c e n e r g y , KE, t o v e l o c i t y , KE = 1/2 mv^ (14) w h i c h upon s u b s t i t u t i o n i n t o e q u a t i o n ( 13 ) y i e l d s f ( E ) = 2 7 T 1 / 2 ( 1/kT ) 3 / 2 exp ( - E / k T g ) E l / 2 dE (15) where, f ( E ) dE = t h e p r o b a b i l i t y f u n c t i o n t h a t a p a r t i c l e has an e n e r g y i n t h e r e g i o n o f E and E + dE m = mass of p a r t i c l e ( kg ) Tg = gas k i n e t i c t e m p e r a t u r e ( K ) - 5 -1 k = B o l t z m a n n ' s c o n s t a n t ( 8.617 x 10 eV K ) E = e n e r g y of p a r t i c l e ( e l e c t r o n v o l t s , eV ). When t h e p a r t i c l e i n q u e s t i o n i s an e l e c t r o n , t h e n f ( E ) y i e l d s t h e e n e r g y d i s t r i b u t i o n o f e l e c t r o n s and i s t h e e l e c t r o n t e m p e r a t u r e , T . 1.5.2 BOLTZMANN DISTRIBUTION F o r p r o c e s s e s i n v o l v i n g t h e e x c i t a t i o n o f a t o m i c s p e c i e s ( b o t h n e u t r a l atoms and c h a r g e d i o n s ), t h e r a t i o of number 1 5 d e n s i t i e s of atoms ( or i o n s ) i n two e n e r g e t i c a l l y d i f f e r e n t bound s t a t e s i s g i v e n by t h e r a t i o of B o l t z m a n n d i s t r i b u t i o n s n /n = g /g exp ( - ( E - E )/kT ) (16) q' p q p q P exc where, n p ' n q = number d e n s i t y of p a r t i c l e s i n s t a t e s p and q g ,g = s t a t i s t i c a l d e g e n e r a c i e s o f s t a t e s p and q ^ P E ,E = e x c i t a t i o n e n e r g i e s of e x c i t e d s t a t e s p and q Q P T = e x c i t a t i o n ( o r B o l t z m a n n ) t e m p e r a t u r e of t h e € X C spec i e s . I t i s a l s o p o s s i b l e t o r e l a t e t h e number d e n s i t y of a p a r t i c u l a r a t o m i c ( o r i o n i c ) e x c i t e d s t a t e n , t o t h e t o t a l number d e n s i t y of atoms ( o r i o n s ) n T w i t h t h e f o l l o w i n g form of t h e B o l t z m a n n d i s t r i b u t i o n n p / n T " VQ(T) 6 X P ( " E p A T e x c > ( 1 7 ) where, Q(T) = the p a r t i t i o n f u n c t i o n o f t h e s p e c i e s . A method f o r e s t i m a t i n g t h e p a r t i t i o n f u n c t i o n f o r most e l e m e n t s , a t v a r i o u s t e m p e r a t u r e s , has been p u b l i s h e d [41]. 16 1.5.3 SAHA DISTRIBUTION F o r i o n i z a t i o n / r e c o m b i n a t i o n p r o c e s s e s of t h e t y p e X « » X + + e , (18) t h e e q u i l i b r i u m c o n s t a n t , S ( T ) , i s g i v e n by S n ( T ) = n q V n p <19) where, n ^ + = number d e n s i t y of i o n s i n s t a t e q n = number d e n s i t y of atoms i n s t a t e p n = number d e n s i t y of e l e c t r o n s , e The e q u i l i b r i u m c o n s t a n t may be w r i t t e n as S (T) = n + n /n n q e / p = 2 g p + / g q ( 2 7 r m e k T i / h 2 ) 3 / 2 exp ( - ( E i + E * g - E n p ) / k T i ) (20) where, h = P l a n c k ' s c o n s t a n t m = mass of e l e c t r o n e E^ = i o n i z a t i o n p o t e n t i a l of s p e c i e s X 17 = e x c i t a t i o n e n e r g y of i o n i c s t a t e q = e x c i t a t i o n e n e r g y of a t o m i c s t a t e p. I f n u m e r i c a l s u b s t i t u t i o n s a r e made f o r t h e c o n s t a n t s , t h e - 3 r e s u l t i n g e x p r e s s i o n , a s s u m i n g d e n s i t i e s a r e measured i n cm , i s g i v e n as n q + n e / n p = ( g g + / g p ) ( 4.84 x 1 0 1 5 ) T ^ 2 exp ( -E/kT\ ) (21 ) where, E = E. + E + - E l nq np I f p a r t i t i o n f u n c t i o n s f o r a l l i o n and atom s p e c i e s a r e i n c l u d e d ( Q + ( T ) and Q(T) r e s p e c t i v e l y ), t h e Saha e x p r e s s i o n may be w r i t t e n f o r t h e t o t a l number d e n s i t y of i o n s ( n ^ + ) and atoms ( n T ) as f o l l o w s : n T + n e / n T = ( 4.84 x 1 0 1 5 ) T V 3 7 2 ( Q + ( T ) / Q ( T ) ) exp ( - E i / k T i ) . ( 22 ) The Saha e q u a t i o n h o l d s f o r any two l e v e l s p and q between any two a d j a c e n t i o n i z a t i o n s t a g e s . 18 1.5.4 GULDBERG - WAAGE DISTRIBUTION F o r r e a c t i o n s of t h e t y p e [ AB ] « • [ A ] + [ B ] (23) the G u l d b e r g - Waage e q u a t i o n g i v e s a r e l a t i o n s h i p between t h e number d e n s i t i e s of t h e p r o d u c t s A and B, n A and n f i, and t h e number d e n s i t y of t h e m o l e c u l e AB, n A B , by t h e e x p r e s s i o n n A n B / n A B = ( Q A ( T ) Q B ( T ) / Q A B ( T ) ) ( m ^ / ( m ^ ) ) 3 / 2 ( 2 7 r k T , / h 2 ) 3 / 2 exp (-E._/kT,) (24) where, Q A ( T ) Q B ( T ) Q A B ( T ) m A,m B,m A B E A B i n t e r n a l p a r t i t i o n f u n c t i o n f o r A i n t e r n a l p a r t i t i o n f u n c t i o n f o r B i n t e r n a l p a r t i t i o n f u n c t i o n f o r AB masses of s p e c i e s A,B, and AB d i s s o c i a t i o n e n e r g y o f m o l e c u l e AB d i s s o c i a t i o n t e m p e r a t u r e . 1.5.5 SUMMARY As was seen i n t h e p r e c e e d i n g s e c t i o n s 1.5.1 t h r o u g h t o 1.5.4, a number of t e m p e r a t u r e s c a n be d e f i n e d : a M a x w e l l i a n t e m p e r a t u r e , T , d e f i n i n g t h e k i n e t i c e n e r g y d i s t r i b u t i o n of 19 p a r t i c l e s ; an e l e c t r o n temperature, T , d e f i n i n g the Maxwellian energy d i s t r i b u t i o n of e l e c t r o n s ; an e x c i t a t i o n temperature, T , d e f i n i n g the atomic e x c i t e d s t a t e p o p u l a t i o n s ( here the cXC term atomic i n c l u d e s both n e u t r a l and charged s p e c i e s ); an i o n i z a t i o n temperature, TV, d e f i n i n g the d i s t r i b u t i o n of atom and ion p o p u l a t i o n s ; and a d i s s o c i a t i o n temperature, , d e f i n i n g the d i s t r i b u t i o n of molecules and t h e i r d i s s o c i a t i o n p roducts. Each of these temperatures can be e x p e r i m e n t a l l y determined and one f i n d s that under c o n d i t i o n s of LTE, T = T = T = T. = T, . (25) g e exc i d However i t has become widely accepted that the ICP i s not i n LTE. The type and extent of departure from LTE w i l l not be d i s c u s s e d here, but ra t h e r in context with e x c i t e d s t a t e l e v e l p o p u l a t i o n s in chapter 3. 1.6 EXCITED STATE LEVEL POPULATIONS The emission i n t e n s i t y , ^ n a ' °£ a s p e c t r a l l i n e r e s u l t i n g from a t r a n s i t i o n from an e x c i t e d s t a t e p to a lower s t a t e q, where s t a t e s p and q l i e w i t h i n the same i o n i z a t i o n stage, i s given by [42] 20 = ( A hc / 4 f f X r v , ) n pq pq pq p (26) where, A pq t r a n s i t i o n p r o b a b i l i t y c s p e e d of l i g h t X w a v e l e n g t h of t h e t r a n s i t i o n n P number d e n s i t y of e x c i t e d s t a t e p. A f t e r r e a r r a n g i n g t h i s e q u a t i o n and d i v i d i n g b o t h s i d e s by t h e d e g e n e r a c y g, i t can be shown t h a t From t h i s r e l a t i o n s h i p , i t i s p o s s i b l e t o d e t e r m i n e t h e r e l a t i v e p o p u l a t i o n of an e x c i t e d s t a t e p by e x p e r i m e n t a l l y m e a s u r i n g t h e r e l a t i v e l i n e i n t e n s i t y r e s u l t i n g f r o m t h e t r a n s i t i o n from s t a t e s p t o q and t h e n m u l t i p l y i n g t h e i n t e n s i t y by t h e f a c t o r X /gA. U s i n g e x p r e s s i o n (27) w h i c h r e l a t e s e x c i t e d s t a t e l e v e l p o p u l a t i o n s t o e x p e r i m e n t a l l y d e t e r m i n e d e m i s s i o n i n t e n s i t i e s , t h e f o l l o w i n g s t u d y was u n d e r t a k e n . E x c i t e d s t a t e l e v e l p o p u l a t i o n s were d e t e r m i n e d f o r t h r e e a n a l y t e s , F e , Ba and C r , a t v a r i o u s r f i n p u t powers and s p a t i a l p o s i t i o n s . The i n s t r u m e n t a t i o n r e q u i r e d t o measure t h e e m i s s i o n i n t e n s i t i e s i s d i c u s s e d i n c h a p t e r 2 w i t h t h e r e s u l t s p r e s e n t e d i n c h a p t e r 3. A summary o f t h i s work i s p r o v i d e d i n c h a p t e r 4. I _ X _ / g A ^ o< n V g „ . pq pq p q ^ P P (27) 21 CHAPTER 2 EXPERIMENTAL 2.1 INTRUMENTATION A Block diagram of the instrumentation i s p r o v i d e d in f i g u r e 2. The ICP u n i t c o n s i s t e d of a Plasma-Therm Inc. ( Kreeson, N.J. ) HFP-2500E r f generator, an AMN-2500E automatic matching network, an APCS-1 automatic power c o n t r o l u n i t and a PT-2500 plasma t o r c h assembly. The r f generator operated at a frequency of 27.12 MHz and d e l i v e r e d up to 2.5 kW of r f input power to the load c o i l . A l l ICP torches used in t h i s study were c o n s t r u c t e d at the Department of Chemistry Gla s s Shop, U.B.C, from p r e c i s i o n - b o r e quartz t u b i n g . I n t r o d u c t i o n of samples, i n the form of aqueous s o l u t i o n s , was achieved using a Plasma-Therm GN 5601 c o n c e n t r i c g l a s s n e b u l i z e r . Diagrams of the t o r c h and g l a s s n e b u l i z e r are p r o v i d e d i n f i g u r e s 3 and 4 r e s p e c t i v e l y . The spray chamber used was of the c o n v e n t i o n a l c o n c e n t r i c b a r r e l type manufactured by Plasma-Therm Inc. (Model SC-5037). A diagram of the complete t o r c h , spray chamber and n e b u l i z e r assembly i s p r o v i d e d i n f i g u r e 5. The f o l l o w i n g ICP gas flows were maintained for a l l experiments: plasma gas - 12 1pm, a u x i l i a r y gas - 0.4 and 0.0 1pm, and a e r o s o l gas - 0.9 1pm. In the measurement of i r o n s p e c t r a l l i n e i n t e n s i t i e s , no a u x i l i a r y flow was used. However t h i s l e d to severe degradation of the ICP t o r c h and as a r e s u l t 22 LO RF GENERATOR ICP • NEBULIZER SAMPLE TRANSLATION STAGE MICROCOMPUTER ADC TRANSIENT RECORDER Figure 2. Block diagram of Instrumentation, F i g u r e 3. The ICP t o r c h . Dimensions: A=20.37 mm, B=17.39 mm, C=15.86 mm, D=5 mm, E=1.48 mm, F=20 mm, G=20 mm, H=43 mm, 1=20 mm, K=25 mm, L=1 mm, M=3 mm. 24 AEROSOL GAS F i g u r e 4. The c o n c e n t r i c g l a s s n e b u l i z e r . 25 AEROSOL GAS SAMPLE PLASMA GAS AUXILIARY GAS DRAINAGE 5. The ICP t o r c h , spray chamber and c o n c e n t r i c g l a s s n e b u l i z e r . 26 an a u x i l i a r y f l o w o f 0.4 1pm was i m p l e m e n t e d f o r t h e r e m a i n i n g b a r i u m and chromium i n t e n s i t y measurements. The e n t i r e plasma t o r c h a s s e m b l y was mounted on a l i n e a r t r a n s l a t i o n s t a g e d r i v e n by a D a e d a l I n c . ( H a r r i s o n C i t y , Pa ) Model 4979 s t e p p e r motor w h i c h p r o v i d e d h o r i z o n t a l movement p e r p e n d i c u l a r t o t h e o p t i c a l a x i s i n i n c r e m e n t s of 0.0127 mm. A S c h o e f f e l - M c P h e r s o n ( A c t o n , Ma ) Model 2061, 1-meter, C z e r n y T u r n e r monochromator was u s e d as t h e d i s p e r s i v e s y s t e m . The monochromator was e q u i p p e d w i t h a S c h o e f f e l - M c P h e r s o n Model AH-3254, 120 x 140 mm, h o l o g r a p h i c g r a t i n g w i t h 1200 lines/mm. The r e c i p r o c a l l i n e a r d i s p e r s i o n o f t h e LPDA s p e c t r o m e t e r was e q u a l t o 0.833 nm/mm. A l l l i n e i n t e n s i t y measurements r e p o r t e d i n t h i s t h e s i s were p r e f o r m e d u s i n g a R e t i c o n ( S u n n y v a l e , Ca ) Model RL-4096S l i n e a r p h o t o d i o d e a r r a y ( LPDA ). T h i s LPDA c o n s i s t e d of 4096 d i s c r e t e p h o t o d i o d e s 7 /nm wide and mounted on 15 /um c e n t e r s . The h e i g h t of e a c h p h o t o d i o d e was 0.5 mm and t h e o v e r a l l l e n g t h of t h e l i g h t - s e n s i t i v e a r e a o f t h e a r r a y was 61.44 mm. The use of t h e LPDA p e r m i t t e d t h e s i m u l t a n e o u s measurement of s p e c t r a l l i n e s f r o m a w a v e l e n g t h window a p p r o x i m a t e l y 50 nm wide. A M e l c o r ( T r e t o n , N . J . ) M o d e l CP1.4-71-10L t h e r m o e l e c t r i c ( P e l t i e r ) c o o l e r was mounted t o t h e b a c k s i d e of t h e LPDA, a l l o w i n g t h e a r r a y t o be c o o l e d t o -15 C. C o o l i n g t h e a r r a y e l i m i n a t e d a g r e a t d e a l o f t h e d a r k c u r r e n t w h i c h i s u s u a l l y o b s e r v e d a t room t e m p e r a t u r e , t h u s p e r m i t t i n g t h e use of l o n g e r i n t e g r a t i o n t i m e s . The LPDA was p u r g e d w i t h n i t r o g e n t o p r e v e n t 27 the f o r m a t i o n of i c e on i t s s u r f a c e . Readout of t h e a r r a y was a c c o m p l i s h e d u s i n g a R e t i c o n Model RL-4096S-3 e v a l u a t i o n b o a r d . The LPDA was e x p e r i m e n t a l l y d e t e r m i n e d t o have a r e s o l u t i o n ( f u l l w i d t h a t h a l f maximum ) of 0.037 nm u s i n g an e n t r a n c e s l i t w i d t h of 60 /im. Under t h e s e c o n d i t i o n s t h e number of p i x e l s s a m p l i n g t h e f u l l w i d t h h a l f maximum i n t e n s i t y i s 5. Assuming a L o r e n t z i a n l i n e shape, t h e amount of e r r o r i n t h e measured s p e c t r a l l i n e i n t e n s i t i e s i s l e s s t h a n 0.1 % [ 4 3 ] . The e m i s s i o n from t h e ICP was f o c u s s e d w i t h 1:1 i m a g i n g o n t o the e n t r a n c e s l i t s of t h e monochromator u s i n g an O r i e l ( S t r a t f o r d , Ct ) M o d e l 41775 p l a n o - c o n v e x f u s e d s i l i c a l e n s . The l e n s had a d i a m e t e r of 150 mm and a r a d i u s of c u r v a t u r e , R, of 69.80 mm. The f o c a l l e n g t h o f t h e l e n s was c o r r e c t e d f o r a c h r o m a t i c r e s p o n s e u s i n g t h e f o l l o w i n g p r o c e d u r e . L i t e r a t u r e v a l u e s f o r t h e r e f r a c t i v e i n d e x of f u s e d s i l i c a a t v a r i o u s w a v e l e n g t h s [44] were p l o t t e d as a f u n c t i o n o f w a v e l e n g t h and f i t t e d w i t h a f i f t h o r d e r p o l y n o m i a l as shown i n f i g u r e 6. The i m a g i n g d i s t a n c e , w h i c h i s t w i c e t h e f o c a l l e n g t h , was t h e n c a l c u l a t e d as a f u n c t i o n of w a v e l e n g t h u s i n g t h e e q u a t i o n 1 / f ( X ) = ( n ( X ) - 1 ) ( 1/R1 - 1/R 2 ) (28) where, f ( X ) = f o c a l l e n g t h a t w a v e l e n g t h n ( X ) = r e f r a c t i v e i n d e x of f u s e d s i l i c a a t w a v e l e n g t h 28 1.45 i 1 1 1 r 200 300 400 508 600 WAVELENGTH ( nm ) F i g u r e 6. P l o t of r e f r a c t i v e i n d e x o f f u s e d s i l i c a v e r s u s w a v e l e n g t h . R. = r a d i u s of c u r v a t u r e f o r l e n s s u r f a c e f a c i n g e m i s s i o n s o u r c e R 2 = r a d i u s of c u r v a t u r e f o r l e n s s u r f a c e f a c i n g e m i s s i o n s o u r c e F o r t h e l e n s u s e d , R 1 = 69.80 mm and R 2 = 00 . The i m a g i n g d i s t a n c e has been p l o t t e d as a f u n c t i o n of w a v e l e n g t h i n f i g u r e 7 . 2.2 COMPUTER INTERFACING OF LPDA AND DATA ACQUISITION The R e t i c o n e v a l u a t i o n b o a r d p r o v i d e s two c o n t r o l l i n e s , a s t a r t and a c l o c k , w h i c h a r e u s e d i n r e a d i n g out t h e a r r a y d a t a . The s t a r t l i n e c a r r i e s t h e s t a r t p u l s e w h i c h i n d i c a t e s t h e a r r a y has c o m p l e t e d i t s i n t e g r a t i o n and i n i t i a t e s r e a d o u t from t h e 4096 i n d i v i d u a l a r r a y p i x e l s . The t i m e between s t a r t p u l s e s c o n t r o l s t h e l e n g t h of tim e t h e a r r a y i s a l l o w e d t o i n t e g r a t e e l e c t r o m a g n e t i c r a d i a t i o n . I n t e g r a t i o n t i m e s can be c h o s e n f r o m between 10.6 msec and 43.5 sec i n i n c r e m e n t s o f 10 msec by s e t t i n g t h e p r o p e r s e q u e n c e o f 12 b i n a r y s w i t c h e s , l o c a t e d on t h e back p a n e l of t h e d i o d e a r r a y h o u s i n g . The c l o c k l i n e c o n t r o l s t h e r a t e a t w h i c h d a t a i s r e a d from t h e a r r a y and t h e r a t e a t w h i c h d i g i t i z a t i o n and s t o r a g e of t h e a n a l o g s i g n a l t a k e s p l a c e . A t h i r d , v i d e o l i n e c a r r i e s t h e a n a l o g r e a d o u t s i g n a l from t h e a r r a y . Due t o t h e r e l a t i v e l y f a s t d i o d e a r r a y c o n t r o l l e d c l o c k 30 F i g u r e 7. Imaging d i s t a n c e of a f u s e d s i l i c a l e n s , w i t h a r a d i u s of c u r v a t u r e o f 69.80 mm, a s a f u n c t i o n o f w a v e l e n g t h . r a t e of 400 kHz, t h e a n a l o g s i g n a l must f i r s t be s e n t t o a t r a n s i e n t r e c o r d e r , w h i c h was c o n s t r u c t e d i n t h e Department of C h e m i s t r y E l e c t r o n i c Shop, U.B.C. The a n a l o g v i d e o s i g n a l f r o m the a r r a y was d i g i t i z e d by a 1 2 - b i t a n a l o g - t o - d i g i t a l c o n v e r t e r and t h e n s t o r e d i n t h e t r a n s i e n t r e c o r d e r ' s r e a d w r i t e random a c c e s s memory ( RAM ). The d i g i t i z e d d a t a s t o r e d i n t h e RAM of the t r a n s i e n t r e c o r d e r was t h e n r e a d , a t a s l o w e r c l o c k r a t e , i n t o a CompuPro ( V i a s y n , Hayward, Ca ) s y s t e m 816 m i c r o c o m p u t e r e q u i p p e d w i t h a 68000 CPU, 1 Mbyte o f RAM, a 1.2 Mbyte 8 i n c h f l o p p y d i s c , and a 40 Mbyte h a r d d i s c . The i n t e r f a c i n g between t h e t r a n s i e n t r e c o r d e r and t h e m i c r o c o m p u t e r was a c h i e v e d t h r o u g h the use of t h r e e p a r a l l e l p o r t s l o c a t e d on a CompuPro I n t e r f a c e r * 4 c a r d . A c o m p l e t e d i a g r a m o u t l i n i n g t h e i n t e r f a c i n g of t h e LPDA t o t h e c o m p u t e r , v i a t h e t r a n s i e n t r e c o r d e r , i s p r o v i d e d i n f i g u r e 8. The a c q u i s i t i o n of d a t a from t h e LPDA can be b r o k e n down i n t o two o p e r a t i o n s . F i r s t l y , t h e a c q u i s i t i o n of d a t a from t h e a r r a y and s u b s e q u e n t d i g i t i z a t i o n and s t o r a g e i n t h e RAM o f t h e t r a n s i e n t r e c o r d e r , and s e c o n d l y t h e t r a n s f e r of d a t a f r o m t h e RAM of t h e t r a n s i e n t r e c o r d e r t o t h e RAM of t h e c o m p u t e r . F o r a b e t t e r u n d e r s t a n d i n g of t h e s e o p e r a t i o n s , t i m i n g d i a g r a m s have been p r o v i d e d , one c o r r e s p o n d i n g t o t h e a c q u i r e mode, f i g u r e 9, and t h e s e c o n d c o r r e s p o n d i n g t o t h e r e a d o u t mode, f i g u r e 10. In o r d e r t o a c q u i r e d a t a , t h e a c q u i r e l i n e , ACQ, i s s e t h i g h from w i t h i n t h e s o f t w a r e . Once i n t h e a c q u i r e mode, a 32 MICROCOMPUTER , 12 DATA LINES < CONTROL LINES i RESET/ ENABLE ACQ BUSY MEM ADV ADC TRANSIENT RECORDER START CLOCK VIDEO LPDA Figure 8. Diagram of the i n t e r f a c i n g between the LPDA and the CompuPro microcomputer v i a the t r a n s i e n t r e c o r d e r . M I C R O C O M P U T E R ACQ T R A N S I E N T R E C O R D E R TV RESET/ENABLE START CLOCK i / / 1 BUSY MEMORY ADVANCE Figure 9. Timing diagram for the acqui s i t i o n of data from the LPDA. MICROCOMPUTER ACQ RESET/ENABLE MEMORY ADVANCE to TRANSIENT RECORDER y/-y/-rvirui F i g u r e 1 0 . T i m i n g d i a g r a m f o r t h e r e a d o u t o f d a t a from t h e t r a n s i e n t r e c o r d e r . r e s e t / e n a b l e p u l s e i s s e n t t o t h e t r a n s i e n t r e c o r d e r , which r e s e t s t h e c o u n t e r t o memory l o c a t i o n 0. The t r a n s i e n t r e c o r d e r t h e n a w a i t s t h e a r r i v a l of a s t a r t p u l s e from t h e LPDA e v a l u a t i o n b o a r d . Once t h e s t a r t p u l s e has a r r i v e d , t h e t r a n s i e n t r e c o r d e r b e g i n s d i g i t i z a t i o n and s t o r a g e of t h e f i r s t a n a l o g s i g n a l as t h e f i r s t c l o c k p u l s e , f o l l o w i n g t h e s t a r t p u l s e , a r r i v e s and s t e p s t h r o u g h a l l 4096 a n a l o g s i g n a l s w i t h t h e a r r i v a l of e a c h s u c c e s s i v e c l o c k p u l s e . The busy l i n e , w h i c h was s e t h i g h as t h e f i r s t c l o c k p u l s e was r e c e i v e d , i s s e t low once t h e 4095 t n c l o c k p u l s e i s r e c e i v e d i n d i c a t i n g t o t h e computer t h a t t h e a c q u i s i t i o n p r o c e s s has been c o m p l e t e d . Readout of t h e d a t a t o t h e computer i s a c h i e v e d by f i r s t s e t t i n g t h e ACQ l i n e low ( see f i g u r e 10 ) f o l l o w e d by t h e s e n d i n g o f a r e s e t / e n a b l e p u l s e w h i c h r e s e t s t h e c o u n t e r t o memory l o c a t i o n 0. S t a r t i n g w i t h t h e f i r s t memory l o c a t i o n , t h e s t o r e d d i g i t i z e d d a t a i s s e n t v i a t h e 12 d a t a l i n e s t o t h e p a r a l l e l p o r t and s u b s e q u e n t l y s t o r e d i n t h e c o m p u t e r ' s RAM. Once t h e f i r s t d a t a p o i n t i s s u c c e s s f u l l y r e a d and s t o r e d , a p u l s e i s s e n t v i a t h e memory ad v a n c e l i n e , w h i c h i n c r e m e n t s t h e c o u n t e r t o t h e s e c o n d l o c a t i o n and t h e p r o c e s s o f r e a d i n g and s t o r i n g t h e d a t a i s r e p e a t e d . T h i s c o n t i n u e s u n t i l a l l 4096 memory l o c a t i o n s have been r e a d . 36 2.3 SOFTWARE A l l s o f t w a r e used i n t h e a c q u i s i t i o n of e x p e r i m e n t a l d a t a and the s u b s e q u e n t c o m p u t a t i o n s was w r i t t e n i n F o r t r a n - 7 7 ( S i l i c o n V a l l e y S o f t w a r e , C u p e r i t i n o , Ca ) and run on t h e CompuPro 8 1 6 s y s t e m m i c r o c o m p u t e r , w i t h one e x c e p t i o n . The s o f t w a r e c o n t r o l l i n g I/O ( i n p u t / o u t p u t ) c o m m u n i c a t i o n s between t h e t r a n s i e n t r e c o r d e r and t h e CompuPro m i c r o c o m p u t e r was w r i t t e n i n 6 8 0 0 0 a s s e m b l y l a n g u a g e . T h i s p e r m i t t e d a much f a s t e r r a t e of d a t a t r a n s f e r from t h e RAM of t h e t r a n s i e n t r e c o r d e r t o t h e RAM of t h e m i c r o c o m p u t e r t h a n p o s s i b l e u s i n g F o r t r a n programming. The F o r t r a n program u s e d t o c o n t r o l t h e c o l l e c t i o n o f l a t e r a l e m i s s i o n i n t e n s i t i e s and t h e a s s e m b l y l a n g u a g e p r o g r a m u s e d t o c o n t r o l t h e t r a n s f e r o f d a t a from t h e LPDA t o t h e m i c r o c o m p u t e r a r e p r o v i d e d i n A p p e n d i x A. 2.4 SAMPLE PREPARATION AND SELECTION OF ANALYTE CONCENTRATION A l l s o l u t i o n s were f r e s h l y p r e p a r e d from r e a g e n t g r a d e c h e m i c a l s , namely F e S 0 4 * 7 H 2 0 , BaCl 2» H 2 0 and Cr ( N 0 3 ) 3* 9H 20, and d i s t i l l e d w a t e r . The Fe s o l u t i o n was made up i n 0 . 1 N HNO^ t o i n h i b i t t h e f o r m a t i o n o f i r o n o x i d e s . The f o l l o w i n g c o n c e n t r a t i o n s of a n a l y t e were u s e d t h r o u g h o u t t h i s s t u d y : 5 0 0 0 ppm F e , 2 0 0 0 ppm Ba, and 5 0 0 0 ppm C r . In o r d e r t o o b t a i n s u f f i c i e n t i n t e n s i t y f r o m h i g h e n e r g y l i n e s , t h e s e 37 r e l a t i v e l y high a n a l y t e c o n c e n t r a t i o n s were r e q u i r e d . To a v o i d problems, such as s e l f a b s o r p t i o n and changes i n n e b u l i z e r e f f i c i e n c y , a s s o c i a t e d with using high a n a l y t e c o n c e n t r a t i o n s , working curves were c o n s t r u c t e d and the a n a l y t e c o n c e n t r a t i o n s then chosen from w i t h i n the l i n e a r p o r t i o n of the working curve. 2.5 SELECTION OF SPECTRAL LINES The f o l l o w i n g procedure was performed i n s e l e c t i n g s u i t a b l e atom and ion emission l i n e s f o r measurement of Fe, Ba and Cr s p e c t r a l l i n e i n t e n s i t i e s . For each of the three a n a l y t e s , a number of " s p e c t r a l windows", 50 nm i n width, were chosen. The number of windows and the wavelength on which they were ce n t e r e d depended upon the r i c h n e s s of the a n a l y t e ' s atomic spectrum, and the p a r t i c u l a r wavelengths which o f f e r e d the highest c o n c e n t r a t i o n of s p e c t r a l l i n e s . In choosing l i n e s from these windows, a number of c r i t e r i a were followed : (1) no s i g n i f i c a n t s p e c t r a l o v e r l a p s of the l i n e s should occur, (2) the e x c i t a t i o n e n e r g i e s of the v a r i o u s l i n e s should span as wide an energy range as p o s s i b l e , and (3) the l i n e s should be s u f f i c i e n t l y intense as to provide reasonable s i g n a l - t o - n o i s e r a t i o s . 2.6 MEASUREMENT OF SPATIALLY RESOLVED LINE INTENSITIES In order to determine s p a t i a l l y r e s o l v e d , r e l a t i v e l e v e l 38 p o p u l a t i o n s , the f o l l o w i n g procedure was used. The ICP t o r c h e n c l o s u r e , mounted on the t r a n s l a t i o n stage, was moved to a p o s i t i o n such that the focussed image of the plasma appeared j u s t to the r i g h t of the entrance s l i t s of the spectrometer. The t r a n s l a t i o n stage was moved, v i a the stepper motor, to 150 h o r i z o n t a l p o s i t i o n s , each separated by 0.0762 mm. As the focused image of the plasma was stepped a c r o s s the entrance s l i t , the emission i n t e n s i t i e s from the s p e c t r a l l i n e s of i n t e r e s t were measured at each of the 150 h o r i z o n t a l p o s i t i o n s . Generation of foreground minus background l i n e i n t e n s i t i e s was achieved in one of two ways, e i t h e r through s p e c t r a l s t r i p p i n g or "dynamic" background s u b t r a c t i o n . In the case of Fe and Cr l i n e i n t e n s i t i e s , a water blank was run and the measured "background" i n t e n s i t i e s were s t r i p p e d from the foreground i n t e n s i t i e s . In the case of Ba, which r e q u i r e d s e v e r a l s p e c t r a l windows at s e v e r a l i n t e g r a t i o n times, the more time e f f i c i e n t dynamic background s u b t r a c t i o n was employed. As a spectrum was c o l l e c t e d at each h o r i z o n t a l p o s i t i o n , o f f - l i n e , b a s e l i n e i n t e n s i t i e s were s u b t r a c t e d from the peak i n t e n s i t y . Note that due to the extremely weak i n t e n s i t i e s from many of the Cr atom and ion l i n e s , s u f f i c i e n t o f f - a x i s i n t e n s i t y was not a v a i l a b l e and as a r e s u l t s p a t i a l l y r e s o l v e d i n t e n s i t y measurements were not p o s s i b l e . The l i n e p r o f i l e s , r e s u l t i n g from the c o l l e c t i o n of 150 l a t e r a l l i n e i n t e n s i t i e s , were smoothed using a 13-point s i m p l i f i e d l e a s t squares procedure [45]. To o b t a i n r a d i a l 39 i n t e n s i t i e s , t h e s e smoothed l a t e r a l p r o f i l e s were t h e n s u b j e c t e d to an A b e l i n v e r s i o n p r o c e d u r e u s i n g an a s y m m e t r i c A b e l i n v e r s i o n [ 4 6 ] . The end r e s u l t was t h e g e n e r a t i o n of s p a t i a l l y r e s o l v e d l i n e i n t e n s i t i e s b a s e d on e x p e r i m e n t a l l y measured l a t e r a l i n t e n s i t i e s . 2.7 SPECTRAL CORRECTION OF SPECTRAL LINE INTENSITIES The s p e c t r a l r e s p o n s e of t h e LPDA s p e c t r o m e t e r was e s t a b l i s h e d o v e r t h e r a n g e 250 t o 700 nm u s i n g an E l e c t r o O p t i c s A s s o c i a t e s ( P a l a A l t o , Ca ) Model L-10 q u a r t z - i o d i n e , t u n g s t e n f i l a m e n t s t a n d a r d lamp s u p p l i e d w i t h an E l e c t r o O p t i c A s s o c i a t e s Model P-101 power s o u r c e [ 4 7 ] . M e a s u r e d i n t e n s i t i e s were c o r r e c t e d f o r s p e c t r a l r e s p o n s e t o compensate f o r n o n - l i n e a r i t y i n t h e LPDA r e s p o n s e and c h a n g e s i n i t s s e n s i t i v i t y o v e r t h e w a v e l e n g t h r a n g e . 40 CHAPTER 3 EXCITED STATE LEVEL POPULATIONS 3.1 INTRODUCTION One a p p r o a c h t a k e n i n s t u d y i n g a n a l y t e e x c i t a t i o n and i o n i z a t i o n i n t h e ICP has been t h e measurement of t h e e x c i t a t i o n and i o n i z a t i o n t e m p e r a t u r e s w h i c h c h a r a c t e r i z e t h e s e p r o c e s s e s . Under c o n d i t i o n s of LTE, t h e s e two t e m p e r a t u r e s , a l o n g w i t h a l l o t h e r - t e m p e r a t u r e s c h a r a c t e r i z i n g t h e v a r i o u s d i s t r i b u t i o n s i n t h e ICP, w i l l be e q u a l . Thus a s i m p l e method o f c o n f i r m i n g or d i s p r o v i n g t h e e x i s t a n c e of LTE i n t h e ICP i s p o s s i b l e t h r o u g h t h e c o m p a r i s o n of e x p e r i m e n t a l l y d e t e r m i n e d t e m p e r a t u r e s . Mermet [4] r e p o r t e d e x c i t a t i o n t e m p e r a t u r e s d e t e r m i n e d from A r , Fe and T i l i n e i n t e n s i t i e s and f o u n d them t o be c o m p a r a b l e w i t h e a c h o t h e r . However, e l e c t r o n d e n s i t i e s measured i n t h e same s t u d y from S t a r k b r o a d e n i n g ( a l s o known as c o l l i s i o n a l b r o a d e n i n g ) o f t h e H^ l i n e , s u g g e s t e d a much h i g h e r e x c i t a t i o n t e m p e r a t u r e , a s s u m i n g Saha e q u i l i b r i u m . K a l n i c k y e t a l . [48] c a l c u l a t e d e l e c t r o n d e n s i t i e s b a s e d on t h e m e a s u r e d i o n - a t o m e m i s s i o n i n t e n s i t y r a t i o s o f f i v e a n a l y t e s , Ca, Mg, F e , Cd, and Zn, v i a t h e Saha e q u a t i o n u s i n g an F e ( I ) e x c i t a t i o n t e m p e r a t u r e as t h e Saha t e m p e r a t u r e . These e l e c t r o n d e n s i t i e s were f o u n d t o be 30-50 t i m e s l e s s t h a n d e n s i t i e s d e t e r m i n e d u s i n g a s e c o n d method, namely S t a r k b r o a d e n i n g of t h e 41 l i n e . In a s t u d y p u b l i s h e d by J a r o s z e t a l . [ 3 ] , e x c i t a t i o n t e m p e r a t u r e s d e t e r m i n e d from Fe, T i and V were f o u n d t o be c o n s i d e r a b l y l e s s t h an t h e i o n i z a t i o n t e m p e r a t u r e d e t e r m i n e d from A r , a s s u m i n g L T E . The c o n c l u s i o n from t h e s e and o t h e r s i m i l a r s t u d i e s was t h a t s i g n i f i c a n t d e v i a t i o n s f r o m LTE e x i s t i n t h e ICP. However the i n f o r m a t i o n p r o v i d e d by t h e s e measurements was i n s u f f i c i e n t t o g i v e a c l e a r i n s i g h t i n t o t h e n a t u r e and e x t e n t of t h e d e v i a t i o n s . A s e c o n d a p p r o a c h t o u n d e r s t a n d i n g a n a l y t e e x c i t a t i o n and i o n i z a t i o n i n t h e ICP has been t h r o u g h t h e measurement o f a n a l y t e i o n - a t o m i n t e n s i t y r a t i o s . In two s t u d i e s by C a u g h l i n and B l a d e s [ 4 9 , 5 0 ] , i o n - a t o m e m i s s i o n i n t e n s i t y r a t i o s were measured e x p e r i m e n t a l l y , ( I . / I ) , f o r f i v e a n a l y t e s , S r , Ca, Mg, Cd, and Zn. The e x p e r i m e n t a l r a t i o s were compared t o t h e c o r r e s p o n d i n g LTE r a t i o s , ( I . / I )rmc> c a l c u l a t e d u s i n g t h e a p p r o p r i a t e e q u a t i o n s and e l e c t r o n t e m p e r a t u r e s d e t e r m i n e d from e l e c t r o n d e n s i t i e s . The r a t i o of ( I . / I )„,,„ t o ( I . / I ) r r T,„, l a i L A f l a L i t r e f e r r e d t o as t h e b r v a l u e , was d e t e r m i n e d f o r r . f . i n p u t powers r a n g i n g f r o m 1.0 t o 2.0 kW. The b r v a l u e s f o r Cd, Mg and Zn showed a moderate dependence on r f i n p u t power i n c r e a s i n g from 0.2 t o 0.5 f o r Mg and Zn and from 0.6 t o 0.8 f o r Cd upon g o i n g from 1.00 kW t o 2.00 kW. The b r v a l u e s f o r Sr and Ca, w h i c h have t h e two l o w e s t i o n i z a t i o n p o t e n t i a l s c f t h e f i v e a n a l y t e s , 42 expressed a strong dependence on r f input power i n c r e a s i n g from 0.2 f o r both elements at 1.0 kW to 1.2 for Ca and 1.5 f o r Sr at 2.0 kW. Degree of i o n i z a t i o n , a , was a l s o determined from the ion-atom i n t e n s i t y data and compared to values c a l c u l a t e d under c o n d i t i o n s of LTE. By c o n s t r u c t i n g a p l o t of a versus i o n i z a t i o n p o t e n t i a l i t was observed that a l l f i v e a n a l y t e s were un d e r i o n i z e d with respect to an LTE model. The r e s u l t s of t h i s study c l e a r l y i n d i c a t e d the absence of LTE i n the ICP and suggested that the c o n t r i b u t i o n of r a d i a t i v e d e - e x c i t a t i o n and recombination, which r e s u l t s i n the l o s s of energy from the system, may be the root cause f o r the d e p a r t u r e s . One shortcoming of measuring e x c i t a t i o n and i o n i z a t i o n temperatures and ion-atom emission i n t e n s i t y r a t i o s , i s the assumption of Boltzmann populated e x c i t e d s t a t e s . E x c i t a t i o n , or Boltzmann, temperatures are u s u a l l y determined using the two l i n e method which i n v o l v e s e x p e r i m e n t a l l y measuring the l i n e i n t e n s i t y from two emission l i n e s w i t h i n the same i o n i z a t i o n stage. An e x c i t a t i o n temperature can then be determined from these measured i n t e n s i t i e s u s i n g the Boltzmann formula given i n equation (16). I o n i z a t i o n , or Saha, temperatures are determined by measuring the l i n e i n t e n s i t y of an atom and an ion emission l i n e . An i o n i z a t i o n temperature can then be determined using these l i n e i n t e n s i t i e s and a measured e l e c t r o n d e n s i t y v i a the Saha equation (21). In both cases the assumption i s made that the p o p u l a t i o n of e x c i t e d s t a t e s proceeds a c c o r d i n g to the Boltzmann 43 d i s t r i b u t i o n . In o t h e r words by m e a s u r i n g o n l y two atom or i o n l i n e s i n t h e c a s e of e x c i t a t i o n t e m p e r a t u r e s , or o n l y one atom and one i o n l i n e i n t h e c a s e o f i o n i z a t i o n t e m p e r a t u r e s , i t i s assumed t h a t t h e t e m p e r a t u r e s d e t e r m i n e d w i l l be i n d e p e n d e n t of t h e e x c i t a t i o n e n e r g y of t h e l i n e s c h o s e n . S i m i l a r l y , i n t h e s t u d i e s u s i n g i o n - a t o m r a t i o s o n l y one atom and one i o n e m i s s i o n l i n e was c h o s e n f o r e a c h of t h e f i v e a n a l y t e s . Thus any d e p a r t u r e s i n t h e B o l t z m a n n p o p u l a t i o n of e x c i t e d s t a t e s , which might e x i s t f o r some o r a l l of t h e a n a l y t e s s t u d i e d , would go u n d e t e c t e d . In l i g h t o f t h e e v i d e n c e s u p p o r t i n g t h e a b s e n c e of L T E , i t may be n a i v e t o assume t h a t t h e e x c i t e d s t a t e s a r e p o p u l a t e d a c c o r d i n g t o t h e B o l t z m a n n d i s t r i b u t i o n and t h a t d e v i a t i o n s do not e x i s t . A more a d v a n t a g e o u s a p p r o a c h would be t o measure as many atom and i o n e m i s s i o n l i n e s as p o s s i b l e and t o use t h e s e i n t e n s i t i e s t o d e t e r m i n e e x c i t e d s t a t e l e v e l p o p u l a t i o n s f o r b o t h i o n i z a t i o n s t a g e s . By d o i n g so i t w o u l d be p o s s i b l e t o d e t e c t any d e v i a t i o n s , w h i c h might e x i s t , i n t h e B o l t z m a n n p o p u l a t i o n of e x c i t e d s t a t e s or i n t h e Saha e q u i l i b r i u m between atom and i o n i o n i z a t i o n s t a g e s . A l s o s i n c e t h e s e l e v e l p o p u l a t i o n s a r e d i c t a t e d by t h e mechanisms c a u s i n g e x c i t a t i o n , i n f o r m a t i o n o b t a i n e d a s a r e s u l t of t h e s e measurements w i l l h e l p t o e l u c i d a t e e x c i t a t i o n mechanisms i n t h e ICP. One of t h e f i r s t c o m p r e h e n s i v e s t u d i e s of e x c i t e d l e v e l s t a t e p o p u l a t i o n s was r e p o r t e d i n 1980 by A l d e r , Bombelka and 44 K i r k b r i g h t [ 5 1 ] . A p l o t was c o n s t r u c t e d of e x c i t e d s t a t e l e v e l p o p u l a t i o n s , l n ( I \ / g A ) , d e t e r m i n e d from 20 F e ( I ) measured l i n e i n t e n s i t i e s , v e r s u s t h e e x c i t a t i o n e n e r g i e s of t h o s e l e v e l s w h i c h r a n g e d from 3.33 t o 6.91 eV. These p l o t s were c o n s t r u c t e d f o r i n t e n s i t i e s c o l l e c t e d a t t h r e e v e r t i c a l p o s i t i o n s , 10, 20 and 30 mm above t h e l o a d c o i l . E x c i t a t i o n t e m p e r a t u r e s were c a l c u l a t e d f r o m t h e r e s u l t i n g n o n - l i n e a r d i s t r i b u t i o n of p o i n t s by s u b d i v i d i n g t h e 20 d a t a p o i n t s i n t o 3 g r o u p s a c c o r d i n g t o t h e i r i n d i v i d u a l e n e r g i e s . T h i s t r e a t m e n t of t h e d a t a y i e l d e d 3 e x c i t a t i o n t e m p e r a t u r e s of i n c r e a s i n g m a g n i t u d e , t h e l o w e s t t e m p e r a t u r e b e i n g d e r i v e d from t h e s e t of low e x c i t a t i o n e n e r g i e s and t h e h i g h e s t t e m p e r a t u r e from t h e s e t of h i g h e x c i t a t i o n e n e r g i e s . T h e i r r e s u l t s i n d i c a t e d an o v e r p o p u l a t i o n of t h e lower e n e r g y l e v e l s and i t was s u g g e s t e d t h a t t h i s o v e r p o p u l a t i o n p r o c e e d s by r a d i a t i v e d e c a y of t h e upper l e v e l s down t o t h e lower l e v e l s , w h i c h i s not b a l a n c e d by t h e i n v e r s e a b s o r p t i o n p r o c e s s e s . As a r e s u l t of t h e n o n - l i n e a r p o p u l a t i o n p l o t s o b s e r v e d , i t was a p p a r e n t t h a t t h e t w o - l i n e t e m p e r a t u r e measurements u s i n g two low l y i n g e n e r g y l e v e l s c o u l d n o t be r e l i e d upon t o r e f l e c t t h e u n i q u e e x c i t a t i o n t e m p e r a t u r e i n t h e ICP. U s i n g some of t h e d a t a p u b l i s h e d by A l d e r , Bombelka and K i r k b r i g h t on e x c i t e d l e v e l s t a t e p o p u l a t i o n s [ 5 1 ] , K o r n b l u m and S m e y e r s - V e r b e r k e r e - e x a m i n e d t h e a p p r o a c h t a k e n by t h e a u t h o r s i n i n t e r p r e t t i n g t h e i r d a t a [ 5 2 ] , They f e l t i t more r e a s o n a b l e t o 45 p o s t u l a t e a c o n t i n u o u s and g r a d u a l change i n e x c i t a t i o n t e m p e r a t u r e between n e i g h b o u r i n g e n e r g y l e v e l s i n s t e a d of t h e t h r e e t e m p e r a t u r e s t r u c t u r e p r o p o s e d by t h e a u t h o r s . U s i n g a s t a t i s t i c a l a p p r o a c h t h e y f o u n d t h e s c a t t e r a r o u n d t h e t h r e e p a r t i a l s t r a i g h t l i n e s not t o be s i g n i f i c a n t l y l e s s t h a n t h e s c a t t e r a r o u n d t h e s t r a i g h t l i n e drawn t h r o u g h a l l 20 d a t a p o i n t s . I n s t e a d of t r y i n g t o f o r c e t h e d a t a t o a l i n e a r f i t , t h e a u t h o r s t r i e d v a r i o u s h i g h e r o r d e r p o l y n o m i a l f i t s and f o u n d a s e c o n d o r d e r f i t y i e l d e d t h e s m a l l e s t d e g r e e of s c a t t e r . L e v e l d e p e n d e n t t e m p e r a t u r e s were c a l c u l a t e d f o r e a c h F e l l e v e l and p l o t t e d a g a i n s t e x c i t a t i o n e n e r g y . The t e m p e r a t u r e s were f o u n d t o i n c r e a s e w i t h i n c r e a s i n g e x c i t a t i o n e n e r g y , q u a l i t a t i v e l y t h e same c o n c l u s i o n a r r i v e d a t by A l d e r , Bombelka and K i r k b r i g h t . A s e c o n d s t u d y i n v o l v i n g F e l e x c i t e d s t a t e l e v e l p o p u l a t i o n s u s i n g a F o u r i e r t r a n s f o r m s p e c t r o m e t e r was c a r r i e d o ut by F a i r e s , Palmer and Engleman [53] i n o r d e r t o c o n s t r u c t a v e r t i c a l p r o f i l e of F e l e x c i t a t i o n t e m p e r a t u r e s i n t h e ICP. The a u t h o r s c h o s e t o i n t e r p r e t t h e i r l e v e l p o p u l a t i o n p l o t s as b e i n g l i n e a r and c a l c u l a t e d an u n i q u e e x c i t a t i o n t e m p e r a t u r e f o r e a c h v e r t i c a l p o s i t i o n . From t h e p o p u l a t i o n p l o t p r o v i d e d i n f i g u r e 4 of t h i s p a p e r [ 5 3 ] , p o p u l a t i o n / e n e r g y v a l u e s have been e x t r a c t e d . V a r i o u s l i n e a r r e g r e s s i o n and h i g h e r o r d e r f i t t i n g p rograms were a p p l i e d t o t h i s d a t a , t h e b e s t r e s u l t coming from a s e c o n d o r d e r p o l y n o m i a l f i t , and not from a l i n e a r f i t . The F e l p o p u l a t i o n p l o t f i t t e d u s i n g b o t h t h e s e c o n d o r d e r p o l y n o m i a l f i t and t h e 46 o r i g i n a l l i n e a r r e g r e s s i o n f i t a r e p r o v i d e d i n f i g u r e 11A and 11B r e s p e c t i v e l y . The v a r i a n c e c a l c u l a t e d from t h e s e f i t s r e v e a l e d t h a t t h e s e c o n d o r d e r f i t p r o d u c e d a v a r i a n c e v a l u e h a l f t h a t c a l c u l a t e d from a l i n e a r r e g r e s s i o n f i t . T h i s r e s u l t can a l s o be q u a l i t a t i v e l y c o n f i r m e d upon v i s u a l i n s p e c t i o n of t h e two p l o t s . The l e v e l d e p e n d e n t t e m p e r a t u r e s c a l c u l a t e d from t h e s e c o n d o r d e r f i t y i e l d e d v a l u e s c o m p a r a b l e t o t h o s e f o u n d by K o r n b l u m and S m e y e r s - V e r b e r k e [ 5 2 ] . F u r u t a r e c e n t l y r e p o r t e d a s t u d y o f i o n i z a t i o n and e x c i t a t i o n t e m p e r a t u r e s i n t h e ICP i n w h i c h e x c i t a t i o n t e m p e r a t u r e s were d e t e r m i n e d f rom F e l e x c i t e d s t a t e l e v e l p o p u l a t i o n s [ 2 ] , U n f o r t u n a t e l y o n l y 7 of t h e 20 e m i s s i o n l i n e s m e asured were u s e d i n c o n s t r u c t i n g t h e p o p u l a t i o n p l o t and 6 of t h e s e l i n e s had e x c i t a t i o n e n e r g i e s w h i c h f e l l i n t o one o f two s m a l l e n e r g y r a n g e s . As a r e s u l t t h e i r p o p u l a t i o n p l o t c o n s i s t e d of o n l y t h r e e c l u s t e r s o f p o i n t s w h i c h made i n t e r p r e t a t i o n of t h e p l o t d i f f i c u l t . The a u t h o r c h o s e t o d i v i d e t h e 7 d a t a p o i n t s i n t o 2 g r o u p s y i e l d i n g two e x c i t a t i o n t e m p e r a t u r e s , one c o r r e s p o n d i n g t o low e n e r g y l e v e l s , t h e o t h e r t o h i g h e n e r g y l e v e l s . The c o n c l u s i o n was a l s o r e a c h e d t h a t t h e low e n e r g y atom l e v e l s a p p e a r e d t o be o v e r p o p u l a t e d w i t h r e s p e c t t o t h e h i g h e n e r g y atom l e v e l s . 47 S EXCITATION ENERGY ( «V ) t Figure 11a. A plot of the logarithm of Fel excited state l e v e l populations vs e x c i t a t i o n energy, from data extracted from Faires, Palmer and Engleman [53]. Populations have been f i t t e d to a second order polynomial. EXCITATION ENERGY ( «V ) Figure 11b. A plot of the logarithm of Fel excited state l e v e l populations vs excitation energy, from data extracted from Faires, Palmer and Engleman [53]. Populations have been f i t t e d using linear regression. 48 3.2 R e s u l t s Before discussing the re s u l t s , the structure of an excited state l e v e l population plot w i l l be b r i e f l y examined. For an analyte system in LTE with i t s surroundings, a population plot similar to the one provided in figure 1 2 w i l l be observed. The v e r t i c a l l i n e drawn at E + corresponds to the ionization potential of the analyte thus dividing the populations into those of atom levels on the l e f t and those of ion lev e l s on the r i g h t . Under conditions of LTE the excited state levels w i l l be populated according to the Boltzmann d i s t r i b u t i o n , thus a plot of the natural log of the excited state l e v e l population, ln ( iX/gA ), versus excitation energy, E , w i l l be linear with a slope equal 6 X C to -1/kT , where T i s the excitation temperature. The 6 X C 6 X C slope of the plot , and therefore T , w i l l be the same for both atom and ion l e v e l s . The r e l a t i v e separation between the two Boltzmann plots w i l l y i e l d the ionization temperature,T^, via the Saha equation, which under LTE w i l l be equal to the excitation temperature. If the analyte and plasma are not in LTE, then deviations from t h i s plot are to be expected. Excited state l e v e l populations have been determined for three analytes, Fe, Ba, and Cr from experimentally measured emission l i n e i n t e n s i t i e s . The choice of these three analytes was made after c a r e f u l consideration of the following c r i t e r i a ; ( 1 ) The analyte should have a r i c h emission spectrum with the 49 atom ion Figure 12. A Saha-Boltzmann LTE plot of the logarithm of l e v e l populations as a function of energy. E + and E + are the ionization energies of atomic and ionic species respectively. The l e v e l populations are represented by a single temperature given by the slope of the Saha-Boltzmann l i n e s (-1/kT). 50 s p e c t r a l l i n e s c o v e r i n g a s wide an e x c i t a t i o n r a n g e as p o s s i b l e ; (2) A v a i l a b i l i t y o f r e l i a b l e t r a n s i t i o n p r o b a b i l i t i e s f o r t h e e m i s s i o n l i n e s of t h e p a r t i c u l a r a n a l y t e ; (3) The a n a l y t e s s h o u l d have d i f f e r i n g i o n i z a t i o n p o t e n t i a l s , a l t h o u g h t h e i o n i z a t i o n p o t e n t i a l s s h o u l d n o t be v e r y low nor v e r y h i g h . The t h i r d c r i t e r i o n was c o n s i d e r e d i m p o r t a n t i n c a s e a n a l y t e e x c i t a t i o n and i o n i z a t i o n b e h a v i o u r i s d e p e n d e n t upon i o n i z a t i o n p o t e n t i a l . A n a l y t e s w i t h v e r y low o r v e r y h i g h i o n i z a t i o n p o t e n t i a l s c o u l d n o t be c o n s i d e r e d as t h i s w o u l d l e a d t o e x t r e m e l y low atom p o p u l a t i o n s i n t h e c a s e of low i o n i z a t i o n p o t e n t i a l s and e x t r e m e l y low i o n p o p u l a t i o n s i n t h e c a s e o f h i g h i o n i z a t i o n p o t e n t i a l s . The most i m p o r t a n t l i m i t i n g c r i t e r i o n i n s e l e c t i n g a n a l y t e s was t h e l a c k o f r e l i a b l e t r a n s i t i o n p r o b a b i l i t y d a t a . Fe i s one of t h e most f r e q u e n t l y s p e c t r o s c o p i c a l l y s t u d i e d m e t a l s and as a r e s u l t has some o f t h e most r e l i a b l e t r a n s i t i o n p r o b a b i l i t i e s . B e c a u s e o f t h i s , Fe was more e x t e n s i v e l y s t u d i e d t h a n e i t h e r Ba o r C r , w h i c h had c o n s i d e r a b l y p o o r e r t r a n s i t i o n p r o b a b i l i t i e s . The F e , Ba, and C r i n t e n s i t i e s were m e a s u r e d a t v a r i o u s s p a t i a l p o s i t i o n s and r f i n p u t p o w e r s . F o r e a c h o f t h e t h r e e a n a l y t e s , t h e n a t u r a l l o g o f t h e p o p u l a t i o n s have been p l o t t e d a g a i n s t e x c i t a t i o n e n e r g y f o r b o t h atom and i o n s p e c i e s . R e p r e s e n t i v e e r r o r b a r s have been i n c l u d e d i n one p o p u l a t i o n p l o t o f e a c h o f t h e t h r e e a n a l y t e s ( f i g u r e s 23,27 and 2 9 ) . 5 1 T h e s e e r r o r b a r s i n c l u d e an e s t i m a t e d 10 % e r r o r i n t h e measured i n t e n s i t y and t h e a p p r o p i a t e e r r o r i n gA v a l u e s p r o v i d e d i n T a b l e s I I , I I I and IV. The a p p l i c a t i o n o f t h e LPDA s p e c t r o m e t e r p r o v i d e d a v e r y e f f e c t i v e method of d a t a c o l l e c t i o n r e s u l t i n g i n p o p u l a t i o n p l o t s c o n t a i n i n g upwards of 48 d a t a p o i n t s . In o r d e r t o f a c i l i t a t e t h e i n t e r p r e t a t i o n of t h e p o p u l a t i o n p l o t s , L T E c u r v e s have been drawn i n . The LTE c u r v e s were d e t e r m i n e d by f i r s t s e l e c t i n g t h e a p p r o p r i a t e e l e c t r o n d e n s i t y and e l e c t r o n t e m p e r a t u r e from p r e v i o u s l y m e a s u r e d d a t a [54] c o r r e s p o n d i n g t o t h e p a r t i c u l a r s p a t i a l p o s i t i o n and r f i n p u t power b e i n g c o n s i d e r e d . The e l e c t r o n d e n s i t y and e l e c t r o n t e m p e r a t u r e v a l u e s a r e l i s t e d i n T a b l e I . The c h o i c e of e l e c t r o n t e m p e r a t u r e f o r an L T E t e m p e r a t u r e i s c o n s i s t e n t w i t h t h e a p p r o a c h t a k e n by o t h e r a u t h o r s i n f o r m u l a t i n g an L T E model [ 5 0 , 5 5 ] , A l i n e , w i t h a s l o p e c o r r e s p o n d i n g t o t h e L T E t e m p e r a t u r e , was f i t t e d t o t h e u p p e r e n e r g y atom l e v e l s . I t w ould be p r e f e r a b l e t o p l a c e t h e L T E l i n e t h r o u g h t h e g r o u n d s t a t e i o n p o p u l a t i o n , as i t i s b e l i e v e d t h a t t h e g r o u n d s t a t e i o n and low e n e r g y i o n l e v e l s w i l l be i n o r v e r y c l o s e t o LTE [ 7 ] , However g r o u n d s t a t e p o p u l a t i o n s c a n n o t be m easured i n e m i s s i o n s t u d i e s and t h e l o w e s t i o n e x c i t e d s t a t e has an e n e r g y c o n s i d e r a b l y above t h e g r o u n d s t a t e , e s p e c i a l l y f o r Fe and C r . As a r e s u l t , t h e LTE l i n e was p l a c e d s u c h t h a t i t p a s s e d t h r o u g h t h e u p p e r e n e r g y atom l e v e l s . T h i s i s c o n s i s t e n t w i t h t h e v i e w s o f o t h e r a u t h o r s i n t h a t u p p e r e n e r g y atom l e v e l s w i l l be i n LTE 52 TABLE I LTE T e m p e r a t u r e s C o r r e s p o n d i n g t o Me a s u r e d E l e c t r o n D e n s i t i e s _ 3 E l e c t r o n D e n s i t y (cm ) LTE T e m p e r a t u r e (K) 5 x 1 0 1 4 7317 1.5 x 1 0 1 5 7981 2 . 5 x 1 0 1 5 8370 3 . 5 x 1 0 1 5 8 6 3 9 53 with the ground s t a t e ion p o p u l a t i o n even i f small d e v i a t i o n s i n the lower energy atom l e v e l s e x i s t s [7,55]. The LTE l i n e p a s s i n g through the ion l e v e l s was then c a l c u l a t e d v i a the Saha equation using the LTE ground s t a t e atom p o p u l a t i o n , given by i n t e r c e p t of the LTE l i n e drawn through the atom l e v e l s with the p o p u l a t i o n a x i s , and the appropiate e l e c t r o n d e n s i t y and LTE temperature. 3.3 F E RESULTS S p a t i a l l y r e s o l v e d emission i n t e n s i t i e s were measured f o r 22 atom l i n e s and- 26 ion l i n e s from two s p e c t r a l windows, one c o v e r i n g the wavelength range 243 nm to 291 nm, the second from 343 nm to 391 nm. The i n t e n s i t i e s were c o l l e c t e d at two r f input powers, 1.25 and 1.75 kW, and at two v e r t i c a l h e i g h t s , 8 and 16 mm above the load c o i l . P o p u l a t i o n p l o t s were c o n s t r u c t e d by c a l c u l a t i n g the l o g a r i t h m of l e v e l p o p u l a t i o n s , l n (ml), ( m= X/gA ), and p l o t t i n g them a g a i n s t e x c i t a t i o n energy. The wave len g t h s of the l i n e s chosen, along w i t h t h e i r gA values are given i n Table I I . The emission s p e c t r a from these two s p e c t r a l windows, i n c l u d i n g i d e n t i f i c a t i o n of the l i n e s chosen, are p r o v i d e d i n Appendix B. 3.3.1 F E L E V E L POPULATIONS AT 8 MM ABOVE THE LOAD C O I L R a d i a l dependence of F e l l e v e l p o p u l a t i o n s at 8 mm above the 54 TABLE II Fe l l i n e s E x c i t a t i o n Wavelength (nm) Energy (eV) 388.85 4.80 388.63 3.24 385.99 3.21 382.78 4.80 382.59 4.15 382.04 4.10 381.58 4.73 376.55 6.53 374.95 4.22 373.71 3.37 373.49 4.18 371.99 3.33 368.22 6 . 9 1 365.15 6.15 361.88 4.42 360.89 4.45 360.67 6.1 3 360.55 6.17 358.12 4.32 357.01 4.39 356.54 4.44 355.37 7.06 qA (X10°) % E r r o r * Reference 1 .43 b [57] 0.376 b [57] 0.796 b [57] 6.00 a [57] 4.56 a [57] 6.16 a [57] 8.15 a [57] 5.9 a [57] 7.02 a [57] 1 .29 a [57] 9.76 a [57] 1 .79 a [57] 9.37 a [57] 6. 15 a [57] 5.09 a [57] 4.16 a [57] 1 1 .7 a [57] 6.31 b [57] 12.5 a [57] 7.56 b [57] 3.71 a [57] 7.99 b [57] 55 TABLE I I : c o n t i n u e d F e l l l i n e s Exc i t a t i o n g W a v e l e n g t h (nm) E n e r g y (eV) gA ( X 1 0 ) % E r r o r * R e f e r e n c e 276.18 5.59 0.459 a [58 275.57 5.48 21.1 a [58 275.33 7.77 24.8 c [59 274.65 5.59 11.7 a [58 274.32 5.62 7.20 a [58 273.96 5.51 15.4 a [58 273.07 5.62 1 .00 a [58 272.75 5.59 3.41 b [58 271.44 5.55 3.86 c [59 266.66 8.07 24. 1 c [59 266.47 8.04 26.5 c [59 262.83 4.84 3.43 a [58 262.57 4.77 3.35 a [58 262.-1 7 4.85 0.97 a [58 261.76 4.82 2.62 a [58 261.38 4.85 3.98 a [58 261.19 4.79 8.71 a [58 260.71 4.84 6.63 a [58 259.94 4.77 22. 1 a [58 259.84 4.82 7.85 a [58 259.15 5.82 4.07 c [58 258.59 4.79 6.44 a [58 258.26 5.88 3.09 a [58 256.69 5.91 2.60 c [59 256.35 5.88 5.21 a [58 256.25 5.82 12.8 c [59 * E s t i m a t e d % e r r o r i s : a = +/-10% ; b = +/-15% ; c = +/-25% 56 l o a d c o i l was examined by p l o t t i n g l n (ml) v e r s u s e x c i t a t i o n e n e r g y f o r two r a d i a l p o s i t i o n s , 0.0 mm ( s q u a r e s ) and 1.5 mm ( c i r c l e s ) , t a k e n a t 1.25 kW r f i n p u t power as shown i n f i g u r e 13. The r e l a t i v e m a g n i t u d e s o f l n (ml) a t t h e two r a d i a l p o s i t i o n s a r e i n d i c a t i v e of t h e shape o f t h e s p a t i a l p o p u l a t i o n p r o f i l e ; t h e s m a l l e r t h e d i f f e r e n c e between t h e two l n (ml) v a l u e s , t h e b r o a d e r t h e r a d i a l p o p u l a t i o n p r o f i l e . From t h e d a t a p r e s e n t e d i n t h i s p l o t , t h e shape o f t h e s p a t i a l p o p u l a t i o n p r o f i l e i s d e p e n d e n t upon e x c i t a t i o n e n e r g y , b e i n g b r o a d e r f o r h i g h e r e n e r g y l i n e s . The o v e r a l l l o w e r l e v e l p o p u l a t i o n s e n c o u n t e r e d a t t h e o f f a x i s p o s i t i o n r e l a t i v e t o 0.0 mm, i n d i c a t e s t h e h i g h e s t c o n c e n t r a t i o n o f F e l s p e c i e s o c c u r s a t t h e c e n t e r o f t h e p l a s m a . The most o u t s t a n d i n g f e a t u r e o f t h e l e v e l p o p u l a t i o n s i n f i g u r e 13 i s t h e i r n o n - l i n e a r i t y w i t h r e s p e c t t o e x c i t a t i o n e n e r g y . The d e g r e e o f c u r v a t u r e c a n b e s t be e m p h a s i z e d by c a l c u l a t i n g t h e l e v e l d e p e n d e n t t e m p e r a t u r e s as a f u n c t i o n o f e x c i t a t i o n e n e r g y f o r 0.0 mm r a d i a l p o s i t i o n u s i n g t h e method o u t l i n e d by K o r n b l u m and S m e y e r s - V e r b e k e [ 5 2 ] . T h e s e l e v e l d e p e n d e n t t e m p e r a t u r e s have been c a l c u l a t e d and p l o t t e d i n f i g u r e 14. From t h i s p l o t i t i s o b s e r v e d t h a t e x c i t a t i o n t e m p e r a t u r e s c a n v a r y f r o m a p p r o x i m a t e l y 4500 t o 7000 K. Due t o p r o b l e m s a s s o c i a t e d w i t h u s i n g a s e c o n d o r d e r p o l y n o m i a l t o f i t t h e d a t a , t h e p l o t s u g g e s t s t h a t t h e t e m p e r a t u r e c o n t i n u e s t o i n c r e a s e a t t h e h i g h e r e x c i t a t i o n e n e r g y where i n f a c t i t s h o u l d b e g i n t o l e v e l o f f . The n o n - l i n e a r l e v e l p o p u l a t i o n s and l e v e l 57 r ~r i i i i i i i 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 EXCITATION ENERGY ( eV ) Figure 13. A plot of the logarithm of Fel l e v e l populations determined at 8 mm above the load c o i l and at 1.25 kW rf input power as a function of energy. Radial position; (•) 0 mm, (O) 1.5 mm. 7000 6 0 0 0 -c r 01 vo 5 0 0 0 -4000 i 1 1 1 1 1 1 1 1 3 3 .5 4 4 .5 5 5.5 6 6 .5 7 7 .5 EXCITATION ENERGY ( eV ) Figure 14. Fel level dependent temperatures calculated from Fel level populations determined at 8 mm above the load c o i l , at an rf input power of 1.25 kw and at a radi a l position of 0 mm. dependent temperatures are c o n s i s t e n t with p r e v i o u s f i n d i n g s i n s t u d i e s on F e l l e v e l p o p u l a t i o n s [51,52]. F i g u r e 15 c o n t a i n s a p l o t of F e l l l e v e l p o p u l a t i o n s as a f u n c t i o n of e x c i t a t i o n energy at 1.25 kW. Once again two r a d i a l p o s i t i o n s were examined, 0.0 mm ( squares ) and 1.5 mm ( c i r c l e s ). In c o n t r a s t to the n o n - l i n e a r i t y observed with the F e l l e v e l p o p u l a t i o n s , the F e l l l e v e l s do appear to vary l i n e a r l y with e x c i t a t i o n energy, suggesting the e x i s t a n c e of Boltzmann e q u i l i b r i u m between the F e l l l e v e l s . The e x c i t a t i o n , or Boltzmann, temperature e v a l u a t e d from the slope (-1/kT) was found to be 8200 K at both r a d i a l p o s i t i o n s of 0.0 mm and 1.5 mm. The p o p u l a t i o n p l o t s i n f i g u r e 15 a l s o provide evidence a g a i n s t the importance of asymmetric charge t r a n s f e r as a p o s s i b l e a n a l y t e e x c i t a t i o n / i o n i z a t i o n mechanism. The three uppermost F e l l l e v e l s have t o t a l e n e r g i e s of 15.64, 15.91 and 15.94 eV, with r e s p e c t to the ground s t a t e atom, which are s u f f i c i e n t l y c l o s e to the i o n i z a t i o n p o t e n t i a l of Ar (15.75 eV) to y i e l d s m a l l energy d e f e c t s of between 0.11 and 0.19 eV f o r the r e a c t i o n . The f a c t t h a t these l e v e l s appear to be i n Boltzmann e q u i l i b r i u m with the lower l e v e l s argues a g a i n s t asymmetric charge t r a n s f e r as being a s i g n i f i c a n t e x c i t a t i o n and i o n i z a t i o n mechani sm. Upon comparison of f i g u r e s 13 and 15, a s i m i l a r i t y i s observed i n the p o p u l a t i o n spacing between 0.0 mm and 1.5 mm f o r a l l F e l l l e v e l s and f o r the high energy F e l l e v e l s . T h i s 60 Figure 15. A plot of the logarithm of F e l l l e v e l populations determined at 8 mm above the load c o i l and at 1.25 kW rf input power as a function of energy. Radial position; (•) 0 mm, (O) 1.5 mm. s u g g e s t s a c l o s e c o u p l i n g ( Saha e q u i l i b r i u m ) between t h e upper l e v e l s of t h e atom and t h e e x c i t e d i o n l e v e l s t h r o u g h t h e i o n g r o u n d s t a t e . F u r t h e r e v i d e n c e of t h i s c o u p l i n g i s a p p a r e n t i n t h e s i m i l a r e x c i t a t i o n t e m p e r a t u r e s d e t e r m i n e d from t h e upper F e l l e v e l s ( 7500 K ) and t h e F e l l l e v e l s ( 8200 K ) a t 0.0 mm. F e l l e v e l p o p u l a t i o n s measured a t 1.75 kW and 8 mm above t h e l o a d c o i l a r e p r o v i d e d i n f i g u r e 16. Once a g a i n n o n - l i n e a r i t y i s o b s e r v e d i n t h e l e v e l p o p u l a t i o n s c o r r e s p o n d i n g t o a r a d i a l p o s i t i o n of 0.0 mm. However a t a r a d i a l p o s i t i o n o f 1.5 mm, t h e p o p u l a t i o n p o i n t s can b e s t be a p p r o x i m a t e d by a s t r a i g h t l i n e . The l a c k of c u r v a t u r e i n t h i s d a t a c o l l e c t e d a t 1.5 mm may be a r e s u l t of t h e h i g h e l e c t r o n d e n s i t y e n c o u n t e r e d o f f a x i s a t 1.75 kW. P r e v i o u s measurements i n o u r l a b i n d i c a t e t h e e l e c t r o n 15 -3 d e n s i t y c h a n g e s from between 2.0 t o 2.5 x 10 cm t o 3.5 t o 4.0 15 - 3 x 10 cm as one moves f r o m t h e c e n t e r of t h e p l a s m a t o a r a d i a l p o s i t i o n o f 1.5 mm o f f a x i s a t a v e r t i c a l h e i g h t of 8 mm above t h e l o a d c o i l [ 5 4 ] , The e x c i t a t i o n t e m p e r a t u r e d e r i v e d f o r t h e 1.5 mm l i n e i s 8400 K. T h i s v a l u e c o r r e s p o n d s q u i t e c l o s e l y t o an e l e c t r o n t e m p e r a t u r e of a p p r o x i m a t e l y 8600 K d e r i v e d f r o m 15 -3 an e l e c t r o n d e n s i t y o f 3.5 - 4.0 x 10 cm , s u g g e s t i n g a c l o s e c o u p l i n g between t h e two d i s t r i b u t i o n s . The F e l l l e v e l p o p u l a t i o n s measured a t 1.75 kW and a t two r a d i a l p o s i t i o n s , 0.0 mm ( s q u a r e s ) and 1.5 mm ( c i r c l e s ), a r e p r e s e n t e d i n f i g u r e 17. As was t h e c a s e w i t h t h e F e l l l e v e l p o p u l a t i o n s a t 1.25 kW, t h e F e l l l e v e l p o p u l a t i o n s a t 1.75 kW 62 1 -H 1 1 1 1 1 1 1 1 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 EXCITATION ENERGY ( eV ) Figure 16 . A plot of the logarithm of Fel l e v e l populations determined at 8 mm above the load c o i l and at 1.75 kW rf input power as a function of energy. Radial position; (•) 0 mm, (O) 1.5 mm. F i g u r e 17. A p l o t of t h e l o g a r i t h m of F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 8 mm above t h e l o a d c o i l and a t 1.75 kw r f i n p u t power as a f u n c t i o n o f e n e r g y . R a d i a l p o s i t i o n ; (•) 0 mm, (O) 1.5 mm. a p p e a r t o v a r y l i n e a r l y w i t h r e s p e c t t o e x c i t a t i o n e n e r g y . The e x c i t a t i o n t e m p e r a t u r e s d e r i v e d f r o m t h e two l i n e s i n f i g u r e 17 a r e 8700 K f o r 0.0 mm and 8600 K f o r 1.5 mm. 3.3.2 FE LEVEL POPULATIONS AT 16 MM ABOVE THE LOAD COIL L e v e l p o p u l a t i o n p l o t s f o r F e l and F e l l a t 16 mm above the l o a d c o i l and a t an r f i n p u t power of 1.25 kW a r e p r e s e n t e d i n f i g u r e s 18 and 19 r e s p e c t i v e l y . The F e l p o p u l a t i o n s a p p e a r t o t o be c u r v e d and t h e F e l l p o p u l a t i o n s a r e b e s t r e p r e s e n t e d by s t r a i g h t l i n e s , w hich i s e s s e n t i a l l y t h e same a s t h e f i n d i n g s a t 8 mm above t h e l o a d c o i l f o r t h e same r f i n p u t power. The l i n e a r i t y i n t h e F e l l l e v e l s once a g a i n s u g g e s t s t h e e x i s t e n c e of B o l t z m a n n e q u i l i b r i u m between t h e s e l e v e l s . The e x c i t a t i o n t e m p e r a t u r e d e r i v e d f r o m t h e two F e l l p o p u l a t i o n p l o t s was a p p r o x i m a t e l y 7400 K. The r e l a t i v e l y s m a l l s e p a r a t i o n between t h e p o p u l a t i o n p l o t s a t 0.0 mm and 1.5 mm f o r b o t h F e l and F e l l s p e c i e s i s i n d i c a t i v e of b r o a d r a d i a l p o p u l a t i o n p r o f i l e s . T h i s i s c o n s i s t e n t w i t h t h e r e l a t i v e l y u n i f o r m e x c i t a t i o n c o n d i t i o n s ( t e m p e r a t u r e [56] and e l e c t r o n d e n s i t y [54] ) a s a f u n c t i o n of r a d i a l p o s i t i o n t h a t a r e e n c o u n t e r e d a t t h i s v e r t i c a l h e i g h t . L e v e l - d e p e n d e n t t e m p e r a t u r e s were d e t e r m i n e d f r o m t h e F e l p o p u l a t i o n p l o t a t a r a d i a l p o s i t i o n of 0.0 mm and a r e p r e s e n t e d as a f u n c t i o n of e x c i t a t i o n e n e r g y i n f i g u r e 20. The t e m p e r a t u r e s range from a p p r o x i m a t e l y 5200 K f o r t h e l e v e l s 65 Figure 18. A plot of the logarithm of Fel l e v e l populations determined at 16 mm above the load c o i l and at 1.25 kW rf input power as a function of energy. Radial position; (•) 0 mm, (O) 1.5 mm. a _ l 1 1 1 1 1 1 1 r 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 EXCITATION ENERGY 1 eV ) F i g u r e 19. A p l o t o f t h e l o g a r i t h m o f F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l and a t 1.25 kW r f i n p u t power as a f u n c t i o n of e n e r g y . R a d i a l p o s i t i o n ; (•) 0 mm, (O) 1.5 mm. EXCITATION ENERGY ( eV ) F i g u r e 20. F e l l e v e l d e pendent t e m p e r a t u r e s c a l c u l a t e d from F e l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above th e l o a d c o i l , a t an r f i n p u t power of 1.25 kW and a t a r a d i a l p o s i t i o n of 0 mm. between 3.2 and 3.4 eV t o 8700 K f o r t h e l e v e l s between 6.5 and 7.1 eV. Once a g a i n t h e t e m p e r a t u r e s o b t a i n e d a t h i g h e x c i t a t i o n e n e r g i e s s u g g e s t a c o n t i n u a l i n c r e a s e where i n f a c t t h e t e m p e r a t u r e s s h o u l d b e g i n t o l e v e l o f f . An i n t e r e s t i n g p o i n t i s o b s e r v e d i f e x c i t a t i o n t e m p e r a t u r e s a r e compared f o r F e l and F e l l a t t h e two v e r t i c a l h e i g h t s of 8 mm and 16 mm above t h e l o a d c o i l , a nd a t 1.25 kW r f i n p u t power. The e x c i t a t i o n t e m p e r a t u r e f o r t h e F e l l e v e l s w i t h e x c i t a t i o n e n e r g i e s of between 3.2 and 3.4 eV a r e f o u n d t o i n c r e a s e from 4500 K a t 8 mm t o 5200 K a t 16 mm. T h i s s p a t i a l d e p endence i n t e m p e r a t u r e i s c o n s i s t e n t w i t h f i n d i n g s of F e l t e m p e r a t u r e s t u d i e s u n d e r t a k e n by F a i r e s e t a l . [53] and B l a d e s and C a u g h l i n [ 5 6 ] ; t h a t i s , t h e F e l t e m p e r a t u r e i n c r e a s e s w i t h h e i g h t from 8 mm t o 16 mm above t h e l o a d c o i l . In c o n t r a s t t o t h i s i n c r e a s e i n F e l e x c i t a t i o n t e m p e r a t u r e s a t 1.25 kW, t h e F e l l e x c i t a t i o n t e m p e r a t u r e d e c r e a s e s from 8200 K a t 8 mm t o 7700 K a t 16 mm above t h e l o a d c o i l . F e l and F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l and a t an r f i n p u t power o f 1.75 kW a r e p r o v i d e d i n f i g u r e s 21 and 22 r e s p e c t i v e l y . The F e l p o p u l a t i o n p l o t s a t 0.0 mm and 1.5 mm b o t h c o n t a i n c u r v a t u r e , a l t h o u g h t h e d e g r e e of c u r v a t u r e i s somewhat r e d u c e d from t h a t o b s e r v e d i n t h e a n a l o g o u s p l o t a t 1.25 kW. The F e l l l e v e l s a p p e a r t o v a r y l i n e a r l y w i t h e x c i t a t i o n e n e r g y and y i e l d an e x c i t a t i o n e n e r g y o f a p p r o x i m a t e l y 8000 K f o r b o t h r a d i a l p o s i t i o n s . 69 Figure 21. A plot of the logarithm of Fel l e v e l populations determined at 16 mm above the load c o i l and at 1.75 kW rf input power as a function of energy. Radial position; (•) 0 mm, (O) 1.5 mm. 4 " 3-2" 1 -g_| j j j j j j 1 1 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 EXCITATION ENERGY I eV ) Figure 22. A plot of the logarithm of F e l l l e v e l populations determined at 16 mm above the load c o i l and at 1.75 kW rf input power as a function of energy. Radial position; (•) 0 mm, (O) 1.5 mm. 3.3.3 F E E X C I T E D S T A T E L E V E L P O P U L A T I O N S In o r d e r t o i n v e s t i g a t e o v e r a l l t r e n d s i n t h e Fe l e v e l p o p u l a t i o n s a t t h e two powers and two v e r t i c a l p o s i t i o n s , p o p u l a t i o n p l o t s have been c o n s t r u c t e d w h i c h i n c l u d e b o t h F e l and F e l l l e v e l s on t h e same - p l o t . F i g u r e s 23 and 24 c o n t a i n d a t a c o l l e c t e d a t 8 mm above t h e l o a d c o i l and a t t h e two r f powers of 1.25 and 1.75 kw r e s p e c t i v e l y . F i g u r e s 25 and 26 c o n t a i n d a t a c o l l e c t e d a t 16 mm above t h e l o a d c o i l and a t 1.25 and 1.75 kW r e s p e c t i v e l y . The v e r t i c a l l i n e drawn i n on t h e s e p l o t s c o r r e s p o n d s t o an i o n i z a t i o n p o t e n t i a l of Fe of 7.87 eV. The e x c i t a t i o n e n e r g i e s on t h e a b s c i s s a a r e r e l a t i v e t o t h e atom g r o u n d s t a t e . The s o l i d l i n e s i n t h e s e p l o t s r e p r e s e n t LTE l i n e s w h i c h have been d e t e r m i n e d a c c o r d i n g t o t h e p r o c e d u r e o u t l i n e d i n s e c t i o n 3.1. The most s t r i k i n g o b s e r v a t i o n t o be made from t h e f o u r p o p u l a t i o n p l o t s i s t h e o v e r p o p u l a t i o n of t h e low e n e r g y atom l e v e l s and t h e u n d e r p o p u l a t i o n of t h e i o n l e v e l s w i t h r e s p e c t t o t h e L T E c u r v e s . I t i s a l s o i m p o r t a n t t o n o t i c e t h a t t h e d e g r e e of o v e r p o p u l a t i o n o f t h e F e l l e v e l s and u n d e r p o p u l a t i o n of t h e F e l l l e v e l s d e c r e a s e s upon g o i n g from an r f i n p u t power of 1.25 kW, f i g u r e 23 and 25, t o 1.75 kW, f i g u r e 24 and 26. An o v e r p o p u l a t i o n of F e l l e v e l s i s c o n s i s t e n t w i t h t h e u n d e r p o p u l a t i o n of F e l l l e v e l s as t h e e x c e s s atom p o p u l a t i o n must come from a d e p l e t i o n o f i o n i c l e v e l s . A l s o t h e d e g r e e of 72 2 T i i — i — i — i — i — i — i — i — i — i — i — i — i — r — r 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 EXCITATION ENERGY ( eV ) F i g u r e 23. A p l o t of t h e l o g a r i t h m o f F e l a n d F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 8 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power of 1.25 kw. The s o l i d l i n e s r e p r e s e n t L T E c a l c u l a t e d p o p u l a t i o n s . 28 F i g u r e 24. A p l o t o f t h e l o g a r i t h m o f F e l a n d F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 8 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power of 1.75 kw. The s o l i d l i n e s r e p r e s e n t LTE c a l c u l a t e d p o p u l a t i o n s . i—r i — i — i — i — i — m — i — i — i — i — i — i — r 3 4 5 6 7 8 9 10 11 12 13 14 15 16 EXCITATION ENERGY ( eV ) 0 1 F i g u r e 25. A p l o t of t h e l o g a r i t h m o f F e l and F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power of 1.25 kW. The s o l i d l i n e s r e p r e s e n t L T E c a l c u l a t e d p o p u l a t i o n s . F i g u r e 26. A p l o t of t h e l o g a r i t h m o f F e l and F e l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power of 1.75 kW. The s o l i d l i n e s r e p r e s e n t LTE c a l c u l a t e d p o p u l a t i o n s . o v e r p o p u l a t i o n of F e l l e v e l s d e c r e a s e s w i t h i n c r e a s i n g e x c i t a t i o n e n e r g y , u n t i l t h e upper most l e v e l s f a l l on t h e LTE c u r v e . 3.4 BA RESULTS S p a t i a l l y r e s o l v e d e m i s s i o n i n t e n s i t i e s were measured f o r 8 atom l i n e s and 9 i o n l i n e s from f o u r s p e c t r a l windows, c e n t e r e d a t 273 nm, 410 nm, 470 nm and 573 nm. The i n t e n s i t i e s were c o l l e c t e d a t two r f i n p u t powers, 1.25 and 1.75 kW, and a t one v e r t i c a l h e i g h t of 16 mm above t h e l o a d c o i l . The w a v e l e n g t h of t h e l i n e s c h o s e n , a l o n g w i t h t h e i r gA v a l u e s a r e g i v e n i n T a b l e I I I . The e m i s s i o n s p e c t r a from t h e s e f o u r s p e c t r a l windows, i n c l u d i n g i d e n t i f i c a t i o n of t h e l i n e s c h o s e n , a r e p r o v i d e d i n A p p e n d i x C. 3.4.1 BA EXCITED STATE LEVEL POPULATIONS E x c i t e d s t a t e l e v e l p o p u l a t i o n s o f Ba, i n c l u d i n g b o t h atom and i o n l e v e l s , have been c o n s t r u c t e d f o r d a t a c o l l e c t e d a t r f i n p u t powers o f 1.25 kw and 1.75 kW and a r e p r e s e n t e d i n f i g u r e s 27 and 28 r e s p e c t i v e l y . LTE l i n e s have once a g a i n been d e t e r m i n e d f rom t h e a p p r o p r i a t e e l e c t r o n d e n s i t i e s and e l e c t r o n t e m p e r a t u r e s g i v e n i n T a b l e I . The B a l l l e v e l p o p u l a t i o n s i n f i g u r e 27, w h i c h were c o l l e c t e d a t an r f power of 1.25 kW, show a v e r y c l o s e c o r r e l a t i o n t o t h e 77 TABLE I I I B a l l i n e s W a v e l e n g t h (nm) 597 . 17 590.76 582.63 577.76 435.03 428.31 399.34 393.57 E x c i t a t i o n E n e r g y (eV) 3. 3. 3 3. 4 4 4 4 22 22 54 82 42 31 29 29 gA ( X 1 0 8 ) % E r r o r ' I .45 0.18 68 48 00 48 95 29 d d d d d d d d R e f e r e n c e [60] [60] [60] [60] [60] [60] [60] [60] B a l l l i n e s W a v e l e n g t h (nm) E x c i t a t i o n E n e r g y (eV) o * gA (x10 ) % E r r o r R e f e r e n c e 585, 493, 490, 455, 452, 416, 413, 389, 277, 263, 37 41 00 40 49 60 07 18 1 4 48 2, 2, 5, 2, 5, 5, 5, 5, 7 , 7, 72 51 25 72 25 70 72 70 19 43 0. 192 1 .91 1 .55 4.68 1 .44 1 .48 10.8 6.68 0.80 4.56 b b b a d d b b d d [60] [60] [60] [60] [60] [60] [60] [60] [60] [60] * E s t i m a t e d % e r r o r i s : a = +/-10% ; b = +/-15% ; c = +/-25% ; d = +/-50% 78 16 3 4 5 6 7 8 EXCITATION ENERGY ( eV ) 10 11 12 13 14 F i g u r e 27. A p l o t of t h e l o g a r i t h m o f B a l and B a l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power of 1.25 kW. The s o l i d l i n e s r e p r e s e n t LTE c a l c u l a t e d p o p u l a t i o n s . 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 EXCITATION ENERGY ( eV ) F i g u r e 28. A p l o t o f t h e l o g a r i t h m o f B a l and B a l l l e v e l p o p u l a t i o n s d e t e r m i n e d a t 1 6 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power of 1.75 k W . The s o l i d l i n e s r e p r e s e n t L T E c a l c u l a t e d p o p u l a t i o n s . LTE l i n e . The upper two l e v e l s a p p e a r t o be u n d e r p o p u l a t e d , a l t h o u g h t h e i r d e v i a t i o n from t h e LTE c u r v e i s more l i k e l y t o r e s u l t ' from f a u l t y gA v a l u e s . The lo w e r e n e r g y atom l i n e s i n f i g u r e 27 a p p e a r t o be o v e r p o p u l a t e d w i t h r e s p e c t t o t h e LTE c u r v e . T h i s b e h a v i o u r i s c o n s i s t e n t w i t h the f i n d i n g s i n t h e F e l d a t a . The f a c t t h a t an u n d e r p o p u l a t i o n of B a l l l e v e l s i s not o b s e r v e d i s not s u r p r i s i n g upon r e a l i z i n g t h e d e g r e e of i o n i z a t i o n of Ba. At 1.25 kW, and a t an e l e c t r o n d e n s i t y and 1 5 t e m p e r a t u r e of 1.5 x 10 and 8000 K r e s p e c t i v e l y , l e s s t h a n 1% of t h e Ba e x i s t s a s a t o m i c s p e c i e s due t o i t s r e l a t i v e l y low i o n i z a t i o n p o t e n t i a l of 5.21 eV. Thus a s i g n i f i c a n t i n c r e a s e i n atom p o p u l a t i o n w i l l n ot n e c e s s a r i l y be p a r a l l e l e d by a s i g n i f i c a n t d e c r e a s e i n i o n p o p u l a t i o n . F i g u r e 28 p r e s e n t s Ba l e v e l p o p u l a t i o n s c o l l e c t e d a t an r f i n p u t power o f 1.75 kW. Once a g a i n t h e B a l l l e v e l s show a c l o s e c o r r e l a t i o n t o t h e LTE c u r v e . The B a l l e v e l s a r e o v e r p o p u l a t e d w i t h r e s p e c t t o t h e LTE c u r v e , a l t h o u g h t h e d e g r e e of o v e r p o p u l a t i o n i s somewhat r e d u c e d from t h a t o b s e r v e d a t 1.25 kW. T h i s t y p e o f b e h a v i o u r i s c o n s i s t e n t w i t h t h e f i n d i n g s i n t h e Fe r e s u l t s . 3.5 CR RESULTS Due t o low i n t e n s i t i e s of many of t h e h i g h e r e n e r g y Cr e m i s s i o n l i n e s , measurement of s p a t i a l l y r e s o l v e d i n t e n s i t i e s 81 was not p o s s i b l e . However, 16 C r I and 16 C r I I l i n e i n t e n s i t i e s were measured a t 16 mm above t h e l o a d c o i l , and a t a l a t e r a l p o s i t i o n c o r r e s p o n d i n g t o t h e c e n t e r of t h e p l a s m a , from t h r e e s p e c t r a l windows c e n t e r e d a t 268 nm, 307 nm and 419 nm. In o r d e r t o examine t h e p o s s i b l e i n t r o d u c t i o n of s i g n i f i c a n t e r r o r by u s i n g l a t e r a l i n t e n s i t i e s t o c a l c u l a t e l e v e l p o p u l a t i o n s i n s t e a d of r a d i a l l y r e s o l v e d i n t e n s i t i e s , t h e f o l l o w i n g c o m p a r i s o n was made. R a t i o s of l a t e r a l Fe i n t e n s i t i e s t o t h e c o r r e s p o n d i n g r a d i a l l y r e s o l v e d i n t e n s i t i e s were c a l c u l a t e d from d a t a c o l l e c t e d a t 16 mm above t h e l o a d c o i l . R a t i o s were d e t e r m i n e d f o r b o t h low e n e r g y and h i g h e n e r g y l i n e s . The r e s u l t of t h i s c o m p a r i s o n r e v e a l e d a d i f f e r e n c e o f o n l y 5% was e n c o u n t e r e d between r a t i o s c a l c u l a t e d f r o m h i g h e n e r g y l i n e s and t h o s e from low e n e r g y l i n e s . T h i s s m a l l d i f f e r e n c e would i n d i c a t e t h a t l a t e r a l l y c o l l e c t e d i n t e n s i t i e s a c c u r a t e l y r e f l e c t t h e s p a t i a l i n t e n s i t i e s e n c o u n t e r e d a t t h e c e n t e r of t h e plasma a t a v e r t i c a l h e i g h t of 16 mm. The w a v e l e n g t h s o f t h e l i n e s , a l o n g w i t h t h e i r gA v a l u e s , a r e g i v e n i n T a b l e IV. The e m i s s i o n s p e c t r a f r o m t h e s e t h r e e s p e c t r a l windows, i n c l u d i n g i d e n t i f i c a t i o n of t h e l i n e s c h o s e n , a r e p r o v i d e d i n A p p e n d i x D. 3.5.1 CR EXCITED STATE LEVEL POPULATIONS F i g u r e s 29, 30, 31, 32 and 33 p r o v i d e Cr l e v e l p o p u l a t i o n p l o t s d e t e r m i n e d from i n t e n s i t i e s c o l l e c t e d a t f i v e r f i n p u t 82 TABLE IV C r I l i n e s Exc1 t a t i on W a v e l e n g t h (nm) 435.18 434.45 428.97 427.48 425.44 305.39 302.44 302.16 300.51 300.09 299.66 297.55 290 . 91 276.99 273. 1 9 272.65 E n e r g y (eV) gA (xl0°) % E r r o r R e f e r e n c e 3.88 1 .32 c [60] 3.86 0.99 c [60] 2.89 1 .57 b [60] 2.90 2.14 b [ 60] 2.91 2.84 b [60] 5.09 8.40 c [60] 5.08 11.5 c [ 60] 5.13 35.2 c [60] 5.1 5 6.44 c [60] 5.13 8.0 c [60] 5.12 6.0 c [60] 5.13 4.45 c [60] 5.24 2.04 c [60] 5.48 5.5 c [60] 5.48 3.9 c [60] 5.49 5.25 c [60] 83 TABLE IV: continued CrII l i n e s E x c i t a t i o n Wavelength (nm) Energy (eV) gA (X10 ) % E r r o r Reference 323.41 8.13 7.36 d [60] 318.07 6.44 7.0 d [60] 312.04 6.41 9.0 d [60] 31 1 .87 6.40 6.8 d [60] 305.01 8.38 25.2 d [60] 304.09 8.37 57.6 d [60] 297.97 7.92 21 .6 d [60] 297.19 7.94 28.0 d [60] 292.71 9.02 28.0 d [60] 287.04 6.77 7.8 d [60] 286.26 5.86 5.04 d [60] 284.98 5.86 7.36 d [60] 277.81 9.40 32.0 d [60] 266.60 6.16 4.72 d [60] 265.86 6.15 2.32 d [60] 265.36 6.16 2.10 d [60] * Estimated % e r r o r i s : a = +/-10% ; b = +/-15% ; c = +/-25% ; d = +/-50% 84 F i g u r e 29. A p l o t o f t h e l o g a r i t h m o f C r I and C r I I l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power o f 0.75 kW. The s o l i d l i n e s r e p r e s e n t LTE c a l c u l a t e d p o p u l a t i o n s . B i — i — i — i — i — i — i — h — i — i — i — i — i — i — i — i — r 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 IS 16 EXCITATION ENERGY ( eV ) F i g u r e 30. A p l o t o f t h e l o g a r i t h m o f C r I and C r I I l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power of 1.00 k W . The s o l i d l i n e s r e p r e s e n t LTE c a l c u l a t e d p o p u l a t i o n s . F i g u r e 31. A p l o t of t h e l o g a r i t h m of C r I and C r I I l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm a b o v e t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power of 1.25 kW. The s o l i d l i n e s r e p r e s e n t L T E c a l c u l a t e d p o p u l a t i o n s . F i g u r e 32. A p l o t of t h e l o g a r i t h m of C r I a n d C r I I l e v e l p o p u l a t i o n s d e t e r m i n e d a t 16 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n o f 0 mm and a t an r f i n p u t power of 1.50 kw. The s o l i d l i n e s r e p r e s e n t L T E c a l c u l a t e d p o p u l a t i o n s . B i — i — i — i — i — i — i — h — i — i — i — i — i — i — i — i — r 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 EXCITATION ENERGY ( eV ) F i g u r e 3 3 . A p l o t o f t h e l o g a r i t h m o f C r I and C r I I l e v e l p o p u l a t i o n s d e t e r m i n e d a t 1 6 mm above t h e l o a d c o i l , a t a r a d i a l p o s i t i o n of 0 mm and a t an r f i n p u t power of 1 . 7 5 k W . The s o l i d l i n e s r e p r e s e n t LTE c a l c u l a t e d p o p u l a t i o n s . powers, 0.75 kW, 1.00 kW, 1.25 kW, 1.50 kW and 1.75 kW r e s p e c t i v e l y . LTE c u r v e s have been d e t e r m i n e d from t h e e l e c t r o n d e n s i t i e s and t e m p e r a t u r e s p r e s e n t e d i n T a b l e I , f o r p o p u l a t i o n p l o t s a t a l l r f i n p u t powers. P r o b l e m s i n i n t e r p r e t i n g t h e Cr p o p u l a t i o n p l o t a r i s e from t h e r a t h e r l a r g e e r r o r s a s s o c i a t e d w i t h t h e gA v a l u e s , most v a l u e s were r e p o r t e d i n t h e l i t e r a t u r e w i t h e r r o r s o f +/- 50% ( see T a b l e IV ). Upon e x a m i n i n g f i g u r e s 29, 30, 31, 32 and 33, t h e atom p o p u l a t i o n s a p p e a r o v e r p o p u l a t e d w i t h r e s p e c t t o t h e LTE c u r v e s and t h e i o n p o p u l a t i o n s u n d e r p o p u l a t e d . T h e r e a l s o a p p e a r s t o be a s l i g h t d e c r e a s e i n t h e d e g r e e of o v e r p o p u l a t i o n and u n d e r p o p u l a t i o n upon g o i n g t o h i g h e r r f i n p u t powers. Due t o t h e l i n e a r a p p e a r a n c e o f t h e atom p o p u l a t i o n s w i t h r e s p e c t t o e x c i t a t i o n e n e r g y , i t was p o s s i b l e t o d e t e r m i n e e x c i t a t i o n t e m p e r a t u r e s f o r b o t h atom and i o n l e v e l s and t h e s e t e m p e r a t u r e s a r e p r e s e n t e d i n T a b l e IV. In o r d e r t o compare t h e s e t e m p e r a t u r e s , LTE t e m p e r a t u r e s d e t e r m i n e d f r o m measured e l e c t r o n d e n s i t i e s have a l s o been i n c l u d e d . B o t h C r I and C r I I e x c i t a t i o n t e m p e r a t u r e s show a g e n e r a l t r e n d of i n c r e a s i n g m a g n i t u d e w i t h i n c r e a s i n g r f i n p u t power, w h i c h i s c o n s i s t e n t w i t h t h e t r e n d i n LTE t e m p e r a t u r e s . C r I I e x c i t a t i o n t e m p e r a t u r e s a l s o t e n d t o show more agreement w i t h t h e L T E t e m p e r a t u r e s t h a n C r I e x c i t a t i o n t e m p e r a t u r e s , s u g g e s t i n g a c l o s e r c o u p l i n g of i o n l e v e l s t o t h e d i s t r i b u t i o n of e l e c t r o n e n e r g i e s t h a n atom l e v e l s . 90 TABLE V C r ( I ) and C r ( I I ) E x c i t a t i o n T e m e r a t u r e s and L T E T e m p e r a t u r e s i n K RF I n p u t Power T C r ( D * T C r ( I I ) * T r 0.75 4400 7000 7317 1.00 5100 6600 7736 1.25 5500 6800 7981 1.50 5900 7300 8370 1.75 6000 7500 8639 * E s t i m a t e d E r r o r i n T e m p e r a t u r e i s +/- 150 K 91 3.6 DISCUSSION From e x a m i n i n g t h e p o p u l a t i o n p l o t s p r e s e n t e d i n t h e p r e v i o u s s e c t i o n s , a c o n v e n i e n t framework f o r a d i s c u s s i o n on t h e s e p l o t s would a p p e a r t o be i n t e r m s of p a r t i a l l o c a l thermodynamic e q u i l i b r i u m ( p -LTE ) [ 5 5 ] . p - L T E i s a f r e q u e n t l y o c c u r r i n g d e v i a t i o n from LTE w h i c h i s c h a r a c t e r i z e d by t h e e x i s t e n c e of Saha e q u i l i b r i u m between e x c i t e d atom l e v e l s and t h e i o n g r o u n d s t a t e l e v e l . The atom g r o u n d s t a t e on t h e o t h e r hand d e v i a t e s from t h e Saha e q u i l i b r i u m and from t h e B o l t z m a n n e q u i l i b r i u m w i t h h i g h e r e n e r g y atom l e v e l s . The r e a s o n f o r t h e s e d e v i a t i o n s i n t h e l o w e r e n e r g y atom l e v e l s a r e p r i m a r i l y due t o r a d i a t i v e c o n t r i b u t i o n s t o e x c i t e d s t a t e d e - p o p u l a t i o n i n w h i c h t h e r a d i a t i v e d e - e x c i t a t i o n r a t e becomes c o m p a r a b l e t o t h e c o l l i s i o n a l d e - e x c i t a t i o n r a t e f o r t h e l o w e r e n e r g y l e v e l s . p-LTE can a l s o be c a u s e d by s i g n i f i c a n t t r a n s p o r t c o n t r i b u t i o n s w h i c h g i v e r i s e t o c o n v e c t i o n and d i f f u s i o n of p l a s m a and a n a l y t e spec i e s [ 5 5 ] . R a a i j m a k e r s e t a l . [55] have s u g g e s t e d two a p p r o a c h e s i n d e s c r i b i n g t h e r egime of p - L T E , one i n c o n t e x t w i t h s p e c t r o c h e m i c a l work, t h e s e c o n d i n c o n t e x t w i t h p l a s m a p h y s i c a l work. In s p e c t r o c h e m i c a l work t h e p l a s m a s y s t e m c a n be d e s c r i b e d i n t e r m s o f two t e m p e r a t u r e s , t h e e x c i t a t i o n t e m p e r a t u r e and t h e i o n i z a t i o n t e m p e r a t u r e . The more u s e f u l a p p r o a c h i n d i s c u s s i n g p - LTE w i t h r e s p e c t t o t h i s t h e s i s i s t h e p l a s m a p h y s i c a l a p p r o a c h 9 2 which d e s c r i b e s t h e s y s t e m i n t e r m s of e l e c t r o n d e n s i t y , or e l e c t r o n t e m p e r a t u r e , and an a d d i t i o n a l p a r a m e t e r b , [ 4 9 , 5 5 , 7 ] , which i s d e f i n e d as t h e r a t i o of t h e e x p e r i m e n t a l l y measured a t o m i c l e v e l p o p u l a t i o n , n , and t h e a t o m i c l e v e l p o p u l a t i o n P c a l c u l a t e d from t h e Saha e q u a t i o n , n , v i z p, s b = n /n (30) P P P r S The p a r a m e t e r b p i s u s e d t o d e s c r i b e an o v e r p o p u l a t i o n of t h e a t o m i c l e v e l , ( b p > 1 ), o r an u n d e r p o p u l a t i o n o f t h e a t o m i c l e v e l , ( b p < 1 ). K e e p i n g t h e p a r a m e t e r b p i n mind, t h e f o l l o w i n g c o n c l u s i o n s can be made from t h e Fe, Ba and Cr l e v e l p o p u l a t i o n p l o t s . T h e s e a r e : (1) h i g h e n e r g y atom l e v e l s a p p e a r t o be i n Saha e q u i l i b r i u m w i t h t h e i o n g r o u n d s t a t e . T h i s i s o b s e r v e d as an o v e r l a p of e x p e r i m e n t a l l y measured l e v e l p o p u l a t i o n s w i t h t h e c a l c u l a t e d L T E c u r v e . S i n c e e l e c t r o n d e n s i t y was u s e d t o d e t e r m i n e t h e LTE c u r v e , t h i s s u g g e s t s t h e e q u i l i b r i u m i s m a i n t a i n e d p r i m a r i l y by e l e c t r o n c o l l i s i o n s ; (2) l o w e r atom l e v e l s a p p e a r t o be o v e r p o p u l a t e d w i t h r e s p e c t t o t h e L T E c u r v e . T h i s t r a n s l a t e s t o v a l u e s of b_ > 1. P F u r t h e r m o r e t h e d e g r e e of o v e r p o p u l a t i o n i s d e p e n d e n t on e x c i t a t i o n e n e r g y , b e i n g g r e a t e r f o r l o w e r e n e r g y l e v e l s . At h i g h e x c i t a t i o n e n e r g i e s , b a p p r o a c h e s u n i t y ; 93 (3) t h e d e g r e e of o v e r p o p u l a t i o n of low e n e r g y atom l e v e l s d e c r e a s e s w i t h an i n c r e a s e i n r f i n p u t power. T h e s e f i n d i n g s h e l p t o e l u c i d a t e some of t h e o b s e r v a t i o n s made i n t h e a t o m - i o n i n t e n s i t y r a t i o s t u d i e s d i s c u s s e d i n t h e i n t r o d u c t i o n of t h i s c h a p t e r [ 4 9 , 5 0 ] . The ( I ./I ) I ? V D v a l u e s , d e t e r m i n e d f rom low e n e r g y atom and i o n e m i s s i o n l i n e s , were f o u n d t o be l e s s t h a n t h e ( I . / I 1,™ v a l u e s , t h u s y i e l d i n g b„ I a Li J. tj r v a l u e s < 1. In t h e p o p u l a t i o n p l o t s p r e s e n t e d i n t h i s c h a p t e r , t h i s b e h a v i o u r was o b s e r v e d as an o v e r p o p u l a t i o n o f low e n e r g y atom l e v e l s and u n d e r p o p u l a t i o n o f i o n l e v e l s . I t was a l s o o b s e r v e d t h a t b^ i n c r e a s e d w i t h i n c r e a s i n g r f i n p u t power, w h i c h has been p a r a l l e l e d i n t h e l e v e l p o p u l a t i o n p l o t s by a d e c r e a s e i n t h e d e g r e e of o v e r and u n d e r p o p u l a t i o n w i t h an i n c r e a s e i n t h e r f i n p u t power. The u n d e r - i o n i z a t i o n of a n a l y t e o b s e r v e d i n t h e i o n - a t o m i n t e n s i t y s t u d i e s c an be e x p l a i n e d by t h e o v e r p o p u l a t i o n of low e n e r g y atom l e v e l s and u n d e r p o p u l a t i o n of i o n l e v e l s . I t i s a l s o p o s s i b l e t o compare t h e e x c i t a t i o n t e m p e r a t u r e s d e t e r m i n e d f rom t h e atom and i o n e x c i t e d s t a t e l e v e l p o p u l a t i o n s of t h e t h r e e a n a l y t e s , F e , Ba, C r . In t h e c a s e of F e ( I I ) , B a ( I ) , B a ( I I ) , C r ( I ) , and C r ( I I ) , e x c i t a t i o n t e m p e r a t u r e s were d e t e r m i n e d f rom t h e s l o p e of a l i n e a r r e g r e s s i o n f i t p r e f o r m e d on e a c h s e t o f i o n and atom p o p u l a t i o n s . An e x c i t a t i o n t e m p e r a t u r e f o r t h e F e ( l ) l e v e l s , w h i c h y i e l d e d a n o n - l i n e a r r e l a t i o n s h i p w i t h e x c i t a t i o n e n e r g y , was d e t e r m i n e d from t h e l e v e l d e p e n d e n t t e m p e r a t u r e s c a l c u l a t e d f o r l e v e l s o f i n t e r m e d i a t e e x c i t a t i o n 94 e n e r g y , i n t h e range of 3.5 t o 4 eV. T h e s e e x c i t a t i o n t e m p e r a t u r e s c a l c u l a t e d from d a t a c o l l e c t e d a t 16 mm above t h e l o a d c o i l and c o r r e s p o n d i n g t o a r a d i a l p o s i t i o n of 0 mm o f f a x i s a r e p r o v i d e d i n T a b l e V I . LTE t e m p e r a t u r e s c o r r e s p o n d i n g t o t h e e l e c t r o n d e n s i t i e s e n c o u n t e r e d a t t h e same s p a t i a l p o s i t i o n and a t t h e two r f i n p u t powers a r e a l s o p r o v i d e d . Two t r e n d s i n t h e t e m p e r a t u r e s can be o b s e r v e d . The f i r s t i s t h a t e a c h of t h e e x c i t a t i o n t e m p e r a t u r e s d e t e r m i n e d from F e d ) , B a ( l ) and C r ( I ) a r e c o n s i d e r a b l y l e s s t h a n t h e c o r r e s p o n d i n g e x c i t a t i o n t e m p e r a t u r e d e t e r m i n e d from t h e i o n s p e c i e s , namely F e ( I I ) , B a ( I I ) and C r ( I I ) . B o t h atom and i o n e x c i t a t i o n t e m p e r a t u r e s a r e l e s s t h a n t h e LTE v a l u e , a l t h o u g h t h e d e g r e e of d e p a r t u r e i s l e s s f o r t h e i o n t e m p e r a t u r e s , i n d i c a t i n g a c l o s e r c o u p l i n g of t h e i o n l e v e l s t o t h e e l e c t r o n d i s t r i b u t i o n . The s e c o n d i s t h e i n c r e a s e i n b o t h atom and i o n e x c i t a t i o n t e m p e r a t u r e s upon g o i n g from an r f i n p u t power of 1.25 t o 1.75 kW. T h i s t r e n d i s c o n s i s t e n t w i t h t h e b e h a v i o u r i n t h e LTE t e m e p e r a t u r e s . The s y s t e m s s t u d i e d do a p p e a r f o r t h e most p a r t t o be c o l l i s i o n a l l y d o m i n a t e d , t h a t i s e x c i t a t i o n and i o n i z a t i o n due t o i n e l a s t i c e l e c t r o n c o l l i s i o n s . T h i s t y p e of s y s t e m has been r e f e r r e d t o as an EEK p l a s m a , where EEK r e f e r s t o e l e c t r o n e x c i t a t i o n k i n e t i c s [61 ] . The c o n t r i b u t i o n o f r a d i a t i v e de-e x c i t a t i o n a s a p o s s i b l e d e - e x c i t a t i o n pathway becomes s i g n i f i c a n t o n l y f o r t h e l o w e r e n e r g y atom l e v e l s . U n l i k e t h e i o n g r o u n d s t a t e , w h i c h has a number o f d e - e x c i t a t i o n pathways t o 95 TABLE VI * Fe, Ba, and Cr E x c i t a t i o n T e m p e r a t u r e s a t 1.25 kW and 1.75 kW 1.25 kW RF I n p u t Power T from atom l e v e l s exc T from i o n l e v e l s exc LTE Fe 5700 K 7400 K 7981 K Ba 5700 K 7100 K Cr 5500 K 6800 K 1.75 kW RF I n p u t Power T from atom l e v e l s exc T from i o n l e v e l s exc LTE Fe 7000 K 8000 K 8639 K Ba 6700 K 8100 K Cr 6000 K 7500 K * E s t i m a t e d E r r o r i n E x p e r i m e n t a l l y D e t e r m i n e d T i s +/- 300 K 96 l o w e r e n e r g y atom l e v e l s and t h u s p r e v e n t i n g a b u i l d up of t h e g r o u n d s t a t e p o p u l a t i o n , t h e atom g r o u n d s t a t e does not and becomes a b o t t l e n e c k i n t o w h i c h t h e l o w e r e n e r g y l e v e l s b e g i n t o o v e r p o p u l a t e d . An i n c r e a s e i n r f i n p u t power p r o d u c e s a h i g h e r e l e c t r o n d e n s i t y , w h i c h e n c o u r a g e s c o l l i s i o n a l d e - e x c i t a t i o n , t h u s d e c r e a s i n g t h e s i g n i f i c a n c e of r a d i a t i v e d e - e x c i t a t i o n p r o c e s s e s . T h i s i s o b s e r v e d as a d e c r e a s e i n t h e d e g r e e of o v e r p o p u l a t i o n a t h i g h e r r f i n p u t powers. D e v i a t i o n s between e l e c t r o n t e m p e r a t u r e s and e x c i t a t i o n and i o n i z a t i o n t e m p e r a t u r e s may r e s u l t f r o m s h i f t s i n t h e d i s t r i b u t i o n of e l e c t r o n e n e r g i e s . The M a x w e l l i a n d i s t r i b u t i o n of e l e c t r o n e n e r g i e s a t a t e m p e r a t u r e of 8 0 0 0 K has been p l o t t e d and i s p r o v i d e d i n f i g u r e 3 4 . From s u c h a p l o t i t i s p o s s i b l e t o d i v i d e t h e e l e c t r o n s i n t o one of two g r o u p s ; a b u l k g r o u p c o n t a i n i n g t h e m a j o r i t y of e l e c t r o n s w i t h r e l a t i v e l y low e n e r g i e s , and a t a i l g r o u p w h i c h c o n t a i n s a s m a l l number o f h i g h e r e n e r g y e l e c t r o n s . In f a c t , i f t h e M a x w e l l d i s t r i b u t i o n f u n c t i o n g i v e n i n e q u a t i o n (15) i s i n t e g r a t e d o v e r t h e e n e r g y r a n g e from 0 t o 3 . 0 eV, i t c a n be shown t h a t a t 8 0 0 0 K, 97% o f a l l e l e c t r o n s have e n e r g i e s i n t h i s r a n g e . The r e s u l t o f t h i s i s t h a t r e l a t i v e l y few e l e c t r o n s a r e a v a i l a b l e t o i n d u c e e x c i t a t i o n and i o n i z a t i o n of a n a l y t e . When a t a i l - e l e c t r o n g i v e s r i s e t o e x c i t a t i o n or i o n i z a t i o n , i t l o s e s an amount of e n e r g y c o r r e s p o n d i n g t o t h e e n e r g y r e q u i r e d t o e x c i t e and / o r i o n i z e t h e a n a l y t e and i s removed from t h i s t a i l s e c t i o n . In o r d e r t o 97 F i g u r e 34. Maxwell d i s t r i b u t i o n of e l e c t r o n e n e r g i e s c o r r e s p o n d i n g t o an e q u i l i b r i u m t e m p e r a t u r e of 8000 K. m a i n t a i n t h e M a x w e l l d i s t r i b u t i o n of e l e c t r o n s , some e l e c t r o n s from t h e b u l k g r o u p must i n c r e a s e t h e i r e n e r g i e s t h r o u g h e l e c t r o n - e l e c t r o n c o l l i s i o n s , t h u s b a l a n c i n g l o s s of t a i l -e l e c t r o n s . I f t h e r a t e of l o s s of e l e c t r o n s from t h e t a i l s e c t i o n i s g r e a t e r t h a n t h e r a t e of i n p u t from t h e b u l k , d e v i a t i o n s i n t h e M a x w e l l d i s t r i b u t i o n can be e x p e c t e d . Due t o the r e l a t i v e l y s m a l l number of t a i l - e l e c t r o n s , a s h i f t i n t h e e n e r g y d i s t r i b u t i o n of t h e s e e l e c t r o n s w i l l n ot be p a r a l l e l e d by a s h i f t i n t h e a v e r a g e e l e c t r o n k i n e t i c e n e r g y or e l e c t r o n t e m p e r a t u r e and as a r e s u l t w i l l go u n d e t e c t e d . Thus a n a l y t e b e i n g e x c i t e d and i o n i z e d w i l l see a d i f f e r e n t t e m p e r a t u r e from the b u l k e l e c t r o n t e m p e r a t u r e . 99 CHAPTER 4 SUMMARY In an e f f o r t t o e l u c i d a t e some of t h e m y s t e r i e s s u r r o u n d i n g a n a l y t e e x c i t a t i o n and i o n i z a t i o n i n t h e ICP, e x c i t e d s t a t e l e v e l p o p u l a t i o n s f o r b o t h atom and i o n s p e c i e s have been d e t e r m i n e d f o r t h r e e a n a l y t e s , F e , Ba and C r . P o p u l a t i o n p l o t s were c o n s t r u c t e d from measured e m i s s i o n l i n e i n t e n s i t y c o l l e c t e d a t v a r i o u s s p a t i a l p o s i t i o n s and r f i n p u t powers. A l l l a t e r a l l y c o l l e c t e d l i n e i n t e n s i t y p r o f i l e s were A b e l i n v e r t e d r e s u l t i n g i n r a d i a l l y r e s o l v e d i n t e n s i t i e s . The t a s k of m e a s u r i n g e m i s s i o n l i n e i n t e n s i t i e s was s i m p l i f i e d w i t h t h e a p p l i c a t i o n of a l i n e a r p h o t o d i o d e a r r a y s p e c t r o m e t e r , w h i c h p e r m i t t e d t h e s i m u l t a n e o u s measurement of l i n e i n t e n s i t i e s from a 50 nm wide window. E x c i t e d s t a t e l e v e l p o p u l a t i o n s were d e t e r m i n e d f r o m F e l and F e l l r a d i a l l y r e s o l v e d l i n e i n t e n s i t i e s c o l l e c t e d a t two v e r t i c a l p o s i t i o n s , 8 mm and 16 mm above t h e l o a d c o i l , and a t two r f i n p u t powers, 1.25 kW and 1.75 kW. The F e l l e v e l s showed a n o n - l i n e a r v a r i a t i o n w i t h e x c i t a t i o n e n e r g y , w h i l e t h e F e l l l e v e l s a p p e a r e d t o v a r y l i n e a r l y . G e n e r a l l y s p e a k i n g t h e F e l l o w e r e n e r g y l e v e l s a p p e a r e d o v e r p o p u l a t e d and t h e i o n l e v e l s u n d e r p o p u l a t e d when compared t o L T E l i n e s c a l c u l a t e d from t h e a p p r o p r i a t e e l e c t r o n d e n s i t i e s and t e m p e r a t u r e s . A d i r e c t c o r r e l a t i o n was o b s e r v e d between t h e d e g r e e of d e p a r t u r e 1 0 0 from LTE and t h e e l e c t r o n d e n s i t y , t h e d e p a r t u r e d e c r e a s i n g w i t h i n c r e a s i n g e l e c t r o n d e n s i t y . Due t o t h e n o n - l i n e a r b e h a v i o u r of the F e l l e v e l s , l e v e l d e p e n d e n t t e m p e r a t u r e s were c a l c u l a t e d f o r e a c h F e l l e v e l , showing a v a r i a t i o n of s e v e r a l t h o u s a n d d e g r e e s o v e r t h e e x c i t a t i o n e n e r g y r a n g e of t h e l i n e s . The l e v e l d e p e n d e n t t e m p e r a t u r e s d e t e r m i n e d from t h e h i g h e r e n e r g y F e l l e v e l s were s i m i l i a r t o t h e e x c i t a t i o n s l o p e t e m p e r a t u r e s d e t e r m i n e d from t h e F e l l l e v e l s , s u g g e s t i n g a c o u p l i n g between h i g h e n e r g y atom l e v e l s and t h e g r o u n d s t a t e i o n . E x c i t e d s t a t e l e v e l p o p u l a t i o n s were a l s o d e t e r m i n e d from B a l and B a l l e m i s s i o n l i n e i n t e n s i t i e s c o l l e c t e d a t 16 mm above t h e l o a d c o i l and a t two r f i n p u t powers, 1.25 kW and 1.75 kW. B o t h B a l and B a l l p o p u l a t i o n s a p p e a r e d t o v a r y l i n e a r l y w i t h e x c i t a t i o n e n e r g y . When t h e s e p o p u l a t i o n s were compared t o t h e LTE l i n e s , t h e atom l e v e l s a p p e a r e d o v e r p o p u l a t e d and t h e i o n l e v e l s u n d e r p o p u l a t e d , s h o w i n g c o n s i s t e n c y w i t h t h e r e s u l t s o b t a i n e d f r o m t h e Fe d a t a . E x c i t a t i o n t e m p e r a t u r e s were d e t e r m i n e d f r o m b o t h B a l and B a l l l e v e l s and a t t h e two r f i n p u t powers. C r I and C r I I e m i s s i o n l i n e i n t e n s i t i e s were measured a t t h e on a x i s l a t e r a l p o s i t i o n a t a v e r t i c a l h e i g h t of 16 mm above t h e l o a d c o i l and a t f i v e r f i n p u t powers, 0.75 kW, 1.00 kW, 1.25 kW, 1.50 kW and 1.75 kw. The c o r r e s p o n d i n g p o p u l a t i o n p l o t s were t h e n c o n s t r u c t e d . B o t h C r I and C r I I l e v e l p o p u l a t i o n s a p p e a r e d t o v a r y l i n e a r l y w i t h e x c i t a t i o n e n e r g y . Once a g a i n t h e atom 101 l e v e l s a p p e a r e d o v e r p o p u l a t e d and t h e i o n l e v e l s u n d e r p o p u l a t e d . C o m p a r i s o n of t h e e x c i t a t i o n s l o p e t e m p e r a t u r e s f o r b o t h C r I and C r I I a t a l l f i v e powers r e v e a l e d two t r e n d s : f i r s t l y , an i n c r e a s e i n e x c i t a t i o n t e m p e r a t u r e d e t e r m i n e d from b o t h C r I and C r I I p o p u l a t i o n s w i t h an i n c r e a s e i n r f i n p u t power and s e c o n d l y , a h i g h e r t e m p e r a t u r e d e t e r m i n e d from C r I I l e v e l s t h a n from C r I l e v e l s . C o m p a r i s o n o f t h e e x c i t a t i o n t e m p e r a t u r e s d e t e r m i n e d from a l l t h r e e a n a l y t e s , .Fe, Ba and C r , a t a v e r t i c a l h e i g h t of 16 mm above t h e l o a d c o i l and a t two r f i n p u t powers o f 1.25 kW and 1.75 kW r e v e a l e d s i m i l a r t r e n d s among t h e t h r e e a n a l y t e s . E x c i t a t i o n t e m p e r a t u r e s d e t e r m i n e d from atom e x c i t e d l e v e l s a r e c o n s i s t e n t l y l o w e r t h a n t h o s e d e t e r m i n e d f r o m i o n e x c i t e d l e v e l s . S e c o n d l y , e x c i t a t i o n t e m p e r a t u r e s d e t e r m i n e d from b o t h atom and i o n e x c i t e d s t a t e l e v e l s i n c r e a s e d upon g o i n g from 1.25 kW t o 1.75 kW r f i n p u t power. C o n c l u s i o n s drawn from t h e r e s u l t s i n d i c a t e a n a l y t e e x c i t a t i o n and i o n i z a t i o n i n t h e ICP a p p e a r , f o r t h e most p a r t , t o be c o l l i s i o n a l l y d o m i n a t e d . Low e n e r g y atom l e v e l p o p u l a t i o n s a r e o v e r p o p u l a t e d w i t h r e s p e c t t o L T E , most l i k e l y a r e s u l t o f c o n t r i b u t i o n s o f r a d i a t i v e d e - e x c i t a t i o n as a p o s s i b l e d e - e x c i t a t i o n pathway. The d e g r e e of o v e r p o p u l a t i o n of low e n e r g y atom l e v e l s d e c r e a s e s w i t h an i n c r e a s e i n e l e c t r o n d e n s i t y , w h i c h e n c o u r a g e s c o l l i s i o n a l r a t h e r t h a n r a d i a t i v e d e - e x c i t a t i o n . H i g h e n e r g y atom l e v e l s seem t o be i n Saha 102 e q u i l i b r i u m with the ground s t a t e ion, which i s thought maintained through e l e c t r o n c o l l i s i o n s . 1 0 3 REFERENCES 1. B.L. C a u g h l i n and M.W. B l a d e s , S p e c t r o c h i m . A c t a . , 39B, 1583 ( 1 9 8 4 ) . 2. N. F u r u t a , S p e c t r o c h i m . A c t a . , 40B, 1013 ( 1 9 8 5 ) . 3. J . J a r o s z , J.M. Mermet and J.P. R o b i n , S p e c t r o c h i m . A c t a . , 33B, 55 ( 1 9 7 8 ) . 4. J.M. Mermet, S p e c t r o c h i m . A c t a . , 30B, 383 ( 1 9 7 5 ) . 5. P.W.J.M. Boumans and F . J . De B o e r , S p e c t r o c h i m . A c t a . , 32B, 365 ( 1 9 7 7 ) . 6. M.W. B l a d e s and G.M. H i e f t j e , S p e c t r o c h i m . A c t a . , 37B, 191 ( 1 9 8 2 ) . 7. R . J . L o v e t t , S p e c t r o c h i m . A c t a . , 37B, 969 ( 1 9 8 2 ) . 8. F. A e s c h b a c h , S p e c t r o c h i m . A c t a . , 37B, 987 ( 1 9 8 2 ) . 9. G.I. B a b a t , J . I n s t . 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B a r n e s , S p e c t r o c h i m . A c t a . , 38B, 259 (1983) . 21. R.M. B a r n e s , R.P Khosah and H.S. M a h a n t i , S p e c t r o c h i m . A c t a . , 38B, 291 ( 1 9 8 3 ) . 22. A.A. V e r b e e k , S p e c t r o c h i m . A c t a . , 39B, 599 ( 1 9 8 4 ) . 23. K.A. W o l n i k , F . L . F r i c k e and C M . G a s t o n , S p e c t r o c h i m . A c t a . , 39B, 64 ( 1 9 8 4 ) . 24. N.R. McQuaker and D.F. Brown, D e v e l o p e m e n t s i n A t o m i c Plasma S p e c t r o c h e m i c a l A n a l y s i s , e d i t o r R.M. B a r n e s , Heyden ( 1 9 8 1 ) . 25. K . J . I r g o l i c , R.A. S t o c k t o n and D. C h a k r a b a r t i , S p e c t r o c h i m . A c t a . , 38B, 437 ( 1 9 8 3 ) . 26. N. Omenetto and H.G.C. Human, S p e c t r o c h i m . A c t a . , 39B, 1333 (1984) . 27. A.R. Gray and A.L. D a t e , A n a l y s t , j_06, 1255 ( 1 9 8 1 ) . 28. R.M. B a r n e s , P h i l . T r a n s . R. Soc. Lo n d . A, 305, 499 ( 1 9 8 2 ) . 29. S. G r e e n f i e l d , A n a l y s t , j_0_5, 1032 ( 1 9 8 0 ) . 30. V.A. F a s s e l , A n a l . Chem., 5J_, 1290A ( 1 9 7 9 ) . 31. V.A. F a s s e l , S c i e n c e , 202, 183 ( 1 9 7 8 ) . 105 32. W e b s t e r ' s T h i r d New I n t e r n a t i o n a l D i c t i o n a r y , G.&C. M e r r i a m Company, S p r i n g f i e l d ( 1 9 7 6 ) . 33. R.M. D a g n e l l , D . J . S m i t h , T.S. West and S. G r e e n f i e l d , A n a l . Chim. A c t a . , 54, 397 ( 1 9 7 1 ) . 34. H.C. H o a r e and R.A. M o s t y n , A n a l . Chem., 3_9, 1153 ( 1 9 6 7 ) . 35. A. A z i z , J.A.C. B r o e k a e r t , K. Laqua and F. L e i s , S p e c t r o c h i m . A c t a . , 39B, 1091 ( 1 9 8 4 ) . 36. D.R. H u l l and G. H o r l i c k , S p e c t r o c h i m . A c t a . , 39B, 843 . ( 1 9 8 4 ) . 37. T. I s h i z u k a and Y. Uwamino, S p e c t r o c h i m . A c t a . , 38B, 519 (1983) . 38. M. B l a d e s , " E x c i t a t i o n Mechanisms and D i s c h a r g e C h a r a c t e r i s t i c s : R e c e n t D e v e l o p m e n t s " , i n ICP E m i s s i o n S p e c t r o m e t r y , V o l . 2, P.W.J.M. Boumans, e d . ( i n p r e s s ) . 39. G.H. H i e f t j e , G.D. Rayson and J.W. O l e s i k , S p e c t r o c h i m . A c t a . , 40B, 167 ( 1 9 8 5 ) . 40. L. De G a l a n , S p e c t r o c h i m . A c t a . , 39B, 537 ( 1 9 8 4 ) . 41. L. De G a l a n , R. S m i t h and J.D. W i n e f o r d n e r , S p e c t r o c h i m . A c t a . , 23B, 521 ( 1 9 6 8 ) . 42. H.W. D a r w i n , H i g h P r e s s u r e - H i g h T e m p e r a t u r e s , 2, 359 ( 1 9 7 0 ) . 43. H o r l i c k and W.K. Yuen, A n a l . Chem., 48, 1643 ( 1 9 7 6 ) . s t 44. Handbook of C h e m i s t r y and P h y s i c s 61 E d i t i o n , CRC P r e s s , I n c . , E-393 ( 1 9 8 0 ) . 45. A. S a v i t z k y and M.J.E. G o l a y , A n a l . Chem., 3_8, 1627 ( 1 9 6 4 ) . 106 46. M.W. Blades, Appl. Spectrosc, 37, 371 (1983). 47. R. S t a i r , W.E. Schneider and J.K. Jackson, Appl. Optics, 2, 1151 (1963). 48. D.J. Kalnicky, V.A. Fassel and R.N. Kniseley, Appl. Spect., 3J_, 137 ( 1977). 49. B.L. Caughlin and M.W. Blades, Spectrochim. Acta., 39B, 1583 (1984) . 50. B.L. Caughlin and M.W. Blades, Spectrochim. Acta., 40B, 1539 (1985) . 51. J.F. Alder, R.M. Bombelka and G.F. Kirkbright, Spectrochim. Acta., 35B, 163 (1980). 52. G.R. Kornblum and J . Smeyers-Verbeke, Spectrochim. Acta., 37B, 83 (1982). 53. L.M. Faires, B.A. Palmer and R. Engleman, J r . , Spectrochim. Acta., 3_9B, 819 (1984). 54. B.L. Caughlin and M.W. Blades, Spectrochim. Acta., 40B, 987 (1985). 55. I.J.M.M. Raaijmakers, P.W.J.M. Boumans, B. van der Sude, D.C. Schram, Spectrochim. Acta., 38B, 697 (1983). 56. M.W. Blades and B.L. Caughlin, Spectrochim. Acta., 40B, 579 (1985) . 57. J.M. Bridges and R.L. Kornblith, Astrophys., 192, 793 (1974) . 58. W. Whaling, Technical Report #84A, Kellog Radiation Laboratory, C a l i f o r n i a Institute of Technology, 1985. 107 59. J . M o i t y , A s t r o n . A s t r o p h y s . S u p p l . , S e r . 52, 37 ( 1 9 8 3 ) . 60. W.L. Wiese and G.A. M a r t i n , NBS Monograph 68, U.S. Government P r i n t i n g O f f i c e , W a s h i n g t o n , D.C. ( 1 9 8 0 ) . 61. J.J.A.M. van d e r M u e l l e n , Ph.D. D i s s e r t a t i o n , De T e c h n i s c h e H o g e s h o o l E i n d h o v e n , ( 1 9 8 6 ) . 1 08 APPENDIX A 68000 a s s e m b l y l a n g u a g e p r ogram employed t o c o n t r o l t h e t r a n s f e r of d a t a between t h e LPDA and t h e m i c r o c o m p u t e r . acoijir: r e a d y : d o n e ; lobyte=*ff00£f histat=*ffOO£d busy=*ff00£3 k _ c r =13 k i f = 10 1 1 1 1 1 1 w 1 1 1 w . g l o b l movem. 1 move.1 move.1 move, wove, move, move, move, move,move, move, move, s u b q brie move, move, move.1 move.D move.b nop nop nop move.b b t s t beq bt s t arie move.b move.b nop nop nop move.b move.w PD496A dO-d7/aO-a£, tem p ( a 7 ) + , d 4 ( a 7 ) + , a 5 ( a 7 ) + , a 3 (a7>,d£ ttlobyte,aO # h i s t a t , a l 4*0, d l # b u s y , a 4 <a3),dO d£, a£ #0,(a£)+ #1, dO z e r o #sennurn, a 6 ( a 5 ) , d 5 d6, a£ # * f G , ( a l ) # * b 0 , ( a l ) # * f O , ( a l ) d l , <a4> r e a d y d l , ( a A ) H i # * d O , ( a l ) # $ 9 0 , ( a l ) # * d O , ( a l ) ( a 3 ) , d O * s a v e r e t a d d r i n d4 • s a v e a d d r o f # s c a n s i n a 5 • g e t a d d r o f # p o i n t s i n a 3 • g e t a d d r e s s o f a r r a y s t o r a g e • a d d r e s s o f l o b y t e i n aO • a d d r e s s o f h i b y t e / s t a t u s i n a l •mask f o r b u s y • a d d r e s s o f b u s y s i g n a l • p o i n t s c o u n t e r t o dO • a r r a y a d d r e s s t o a£ • l o a d 0's i n t o a r r a y • g e t # o f s c a n s i n d5 • g e t a d d r e s s o f a r r a y • a c q u i r e mode • s e n d p u l s e t o e n a b l e • t r a n s f e r • e n a b 1 e mode 1 0 9 ne nt : C f i t o u t : err-p : 5 c n n 1.1 m c 1 r d2 c l r d 3 move.b <aO),d£ move.b ( a l ) , d 3 a n d i # * 0 f , d 3 ni u 1 u #£56,d3 a d d . w d£, d 3 a d d . 1 d3, (a£) + s u b q #1, dO beq n e x t move.b # t c O , ( a l ) n o p n o p move.b # * d O , ( a l ) b r a g e t s u b q #1, d5 beq o v e r move.b #*2,dO move.b ( a 6 ) + , d 1 t r a p #2 move.o move.b ( a 6 ) + , d l t r a p #2 move.b #2, dO move.b ( a 6 ) + , d l t r a p #2 move.b #*£,dO move.b # 1 3 , d l t r a p #2 move.o #£, dO move.b # 1 0 , d l t r a p #2 move.1 #0, d l : r a a c q u i r move. 1 d 4 , ( a 7 ) fiiovem. 1 t e m p , d 0 - d 7 / a 0 - a 6 r t s . e v e n . b s s d s . 1 15 . e v e n . d a t a • c l e a r s p a c e • c l e a r s p a c e • g e t l o b y t e • g e t h i b y t e • e r a s e u p p e r 4 b i t s • s h i f t 8 b i t s l e f t • g e n e r a t e t h e 16 b i t n u m b e r • a d d c u r r e n t n u m b e r t o p r e v i o u s • d o n e ? • i f y e s e x i t l o o p • s e n d p u l s e t o • i n c r e m e n t a d d r e s s • a l l s c a n s c o m p l e t e ' 1 • i f no go b a c k a n d g e t m o r e • o t h e r w i s e r e s t o r e s p : d c . • ' 0 0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0 7 ' d c . b '00800901001101£0130140150160170180130200210220230£40£5' d c . b ' 0 2 6 0 2 7 0 2 8 0 2 9 0 3 0 0 3 1 0 3 2 0 3 3 0 3 4 0 3 5 0 3 6 0 3 7 0 3 8 0 3 9 0 4 0 0 4 1 0 4 2 0 4 3 0 4 4 ' dc.D ' 0 4 5 0 4 6 0 4 7 0 4 3 0 4 9 0 5 0 0 5 1 0 5 2 0 5 3 0 5 4 0 5 5 0 5 6 0 5 7 0 5 8 0 5 9 0 6 0 0 6 1 0 6 2 0 6 3 0 6 4 ' d c . P ' 0 6 5 0 6 6 0 6 7 0 6 8 0 6 9 0 7 0 0 7 1 0 7 2 0 7 3 0 7 4 0 7 5 0 7 6 0 7 7 0 7 8 0 7 9 0 8 0 0 8 1 0 8 2 0 8 3 0 8 4 ' d c . 5 ' 0 8 6 0 8 7 0 8 8 0 8 9 0 9 0 0 9 1 0 9 2 0 9 3 0 9 4 0 9 5 0 9 6 0 9 7 0 9 8 0 9 9 1 0 0 1 0 1 0 2 1 0 3 1 0 4 1 0 5 ' a c . b ' 1061071081031101111121131141151161171181131£01211221£3124 125' G C . b ' 1 2 6 1 2 7 1 2 8 1 2 9 1 3 0 1 3 1 1 3 2 1 3 3 1 3 4 1 3 5 1 3 6 1 3 7 1 3 8 1 3 9 1 4 0 1 4 1 1 4 2 1 4 3 1 4 4 1 4 5 ' a c . b ' 1 4 6 1 4 7 1 4 8 1 4 9 1 5 0 1 5 1 1 5 2 1 5 3 1 5 4 1 5 5 1 5 6 1 5 7 1 5 8 1 5 3 1 6 0 1 6 1 1 6 2 1 6 3 1 6 4 1 6 5 ' . e n c 1 1 0 F o r t r a n - 7 7 l a n g u a g e Program used t o c o l l e c t l a t e r a l e m i s s i o n l i n e i n t e n s i t i e s . t» * » * »i MULTI-PROFILE EY ZONE WALKER THIS PROGRAM IS TO BE USED TO COLLECT DATA FROM fl 4096 DIODE ARRAY. ALSO DOES PEAK SEARCH. USE SUBMIT PROGRAM MPDA.SUB; MUST HAVE ACCESS TO THIS PROGRAM AS WELL AS MACHINE LANGUAGE PROGRAM PDA7.0 8 STATUS.• NOTE: THIS PROGRAMM IS OPERATING SYSTEM DEPENDANT! IN ORDER FOR VARIOUS OUTPUT DEVICES TO BE ASSIGNED AS ' LST:' THE NUMBER OF THE THE DEVICE MUST BE PLACED IN THE TWO ALLOCATED MEMORY BYTES (PRESENTLY SF9CDB AND * F 9 D 0 F ) . LAST REVISION JUNE 11, 1985 PROGRAM MAIN REAL F O R E ( 0 : 5 0 , 0 : 1 5 0 ) , B A C K ( 0 : 5 0 , 0 : 1 5 0 ) , F M B ( 0 : 5 0 , 0 : 1 5 0 ) INTEGER*A IADDR I N T E G E R * £ IDIO, IDIO = I N T E G E R * £ I D N ( 5 1 ) , IDIOD, I STEP, ISCN, I PULSE INTEGER*1 I NTT, IVAL COMMON FORE,BACK,FMB, IDIO, IDIOP, I NTT COMMON /BL1/ IDN,IDIOD,ISTEP,ISCN,IPULSE IDI0=4095 I D I 0 P = 4 0 9 £ C O ^ L HOME I.NTT=*FE IADDR=*FFO0l7 IVAL=*04 CAi_L POKE ( IADDR, IVAL) I A D D R = * F - 0 0 1 £ IVAi_ = *FE C A ^ _ POKE ( IADDR, IVA_) I P D D R = S F - 0 0 £ C I V A L = * 9 3 CALL POKE <IADDR, IVAL) IPDDR = S c , r O O £ 0 I VA_=*9B C A _ L POKE ( I A D D ^ , I VRL.) * SET TRANSIENT RECORDER I N THE TRANSFER MODE IVAL=*FO I A D D R = * - F O O £ D CALL POKE (IADDR, 1V0„) * 10 PRINT*, ' READ F R C DISC ( 1 ) ' PRINT*, 'TAKE NEW S 3 t C T R j " < Z > ' PRINT*, ' S E T INTE5RCTI0\ T I M E . 2 ) ' PRINT*,' ' PRINT*,' ' W R I T E ( * , £ 0 ) £ 0 FORMAT ('WHAT WOULD YOU L I K E '0 DO - 1- '\) READ (*, 30) M t- UKI1H M i l ; I F I F I F I F GO 1 ) (M. ED (M. EG.2) (l*,. ED. 3 ) <M. GE. 4 ) TO 1 0 0 C A L L R F D I S C C A - L M P R O ~ CAL.L I N T ' I M GO TO 1 0 *** 1 0 0 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * C A _ L H O ME 1 1 0 13-0 P R I N T * , P R I N T * , P R I N - * , P R I N T * , P R I N T * , P R I N - * , P R I N ^ * , WRITE <* F O R M A T ( R E A D ( * , 1 3 0 ) F O R M A T ( I I ) O A _ L HOME I F ( M . E D . 1 ) I F ( M . E G . 3 ! I F ( M . E D P L C T ( 1 ) ' S T O R E ( 3 ) ' NEW S C A N ( 4 ) ' S E T I N T E G R A T I O N T T R A N S S T A G E ( £ 5 ' R E A D F R O K D I S C ( 7 ) I ME 1 1 0 ) WHAT w: M ~_D YOU \ ) I F I F I F GO STOP END (M. (M. (Mi. T C EC EC ED. 1 0 0 4 ) . 7) co_;_ C A L L C O ^ CAl C O L L CAL.L P..OT STORE MPRC-I N T " J i T R S T G R F D I S C S U B R O U T I N E B E L L . I N ~ E G E R*4 IADDR, I V A ^ * 1 IADDR = tFFOO l~C IVAL=*7 CALi- P O K E < I A D D R , I V A ^ ) R E T U R N E N D S U B R O U T I N E H OME I N T E G E R * 4 I A D D R , I v ' A , _ * l I P . D D R = * F F O O F C I V A _ = * 1 A CALL P O K E < I A D D R , I V f i _ ) R E _ U R N E N D * * * * * * * * * * * * * * * * ***** * * * * * * * * * * * * * * * * * * * * * * * * S U B R O U T I N E MPRD -R E A L F C RE ( 0 : 5 0 , 0 : 1 5 0 ) , E A C - > ( 0 : 5^ , 0 : 1 5 0 ) , - v R E A L R A N G E , P - - 2 E , S ~ E = I N T E G E R * 3 I D I C , ID 1 0 = I N T E G E R * 3 I DN ( 5 1 ) , IDIOD, :-:*EP, ISCN, I T ^ . 3 3 I N T E G E R * 1 I N T T COMMCN F O R E , B A C K , F M B , IDIO, IDICP, IN ~ ~ COIWOK / B _ l / IDN, 1 D I 0 C , 1S~E*. I F C R ' . I ?-.S" C' H A R S C ~ E R * 1 ANS*,YES I X = 0 I Y = 0 3 0 CA_L HOME W R I T E ( * , 1 0 0 ) 1 0 0 F O R M A T (' HOW M A N Y D I C D E S WOULD Y O U _Ir.E "'• C R E A D ( * , 1 1 0 ) I D I O D 1 1 0 F O R M A T ( 1 4 ) DC 1 3 0 J = l , I D I O D W R I T E ( * , 1 3 0 ) 1 2 0 F O R M A T ( ' D I O D E — ' \ ) 1 12 . Htriu (*, i l o j IDN cJ) 1 3 0 CONTINUE C«1_L H 3 * ! £ DO iAO J = l, ID 3ao W R I T E ( * , I S O ) 'DIODE- ',IDNCJ) 1 5 0 FORrPT CP, 16-) 1 4 0 C O N T I N U E : PRINT*. 1 ' PRINT*^' • WRITE ',*, I S O ) 160 FORMRT (' CHPNGE THE DIGOES S-EGIFIED'' (Y DR N ) - '\) READ < * , 1 7 0 ) RNSt/. 170 FORGOT(3) Y E S = ' V ' I F ( A N S * . ED. YES) GG T C 30 D G 1 7 5 J = l , I D I O D F O R E ( J , 0 ) = I D N ( J > B P O K ( J , 0 ) = I D ! * < J ) FITS ( J , 0 ) = I D \ ( J ) 1 7 5 C G \ , T I ^ J E P R I N T * , ' ' PRINT*.' ' W R I T E ( * , I S O ) I S O F O R r R - ( ' RPNGE I N K r - '\) REPD <*, 1 B 2 ) R P N 3 E 1 8 3 FORGOT(FE. 1 ) WRITE ( * , I B S ) I B S FGRMRT (' HQU, K'PN'Y S^EPS- ' \> R E P D ( * , 1 1 0 ) IS"!"E£ ST E P = F L C P T ( I S T E P ) PULSE=(RANGE/S^EP)/ ( 0 . 0 1 E 7 ) ICULSE=INT( 0 j L5E) R P \ 3 E = ( ; f r L C P . T ( I P _ ^ E ! T l ) * r . n i £?)+E~EP WRITE (* , 1 8 7 ) ' RPNGE-' , R P. N 3 E 1 8 7 FORXPT (P, F S . 1 ) "ORE ( 0 , 0 ! =FI_GO_ (IDIOD > B P G K ( 0 , 0 ) = - 1 _ C ! P T ! IDIDD) F f r ( 0 , 0 ) = F L C P ~ ! 1 3 . G O F 3 R E C O , 1 ) =FLQP~ '.' I 3 T E -) BPCX ( 0 , 1 ) =F-_OP.T ( IE"? V ) Flr& ( 0 , 1 ) =-LDPT t IE--EP ; F O R E ( 0 , £ ) = R « \ ' 3 E BRCK ( 0 , E) = R P \ 3 E FWP ( 0 , £ ) = RPrvG>: F O R E ( 0 , 3 ) = P J _ S E EPGK < 0 , 3 ) =3_'_£E F ^ E ( 0 , 2 ) = 3 L'_E . E I P ' ^ L - S E = I N T ( P_:^EF-; ) W R I ~ E ( * , 1 3 0 ) 1 9 0 F O R ^ P - ' ' M J ^ E E R a- s:c\-'.-.- ' \) REPD (*, 1 1 0 ) I S C \ £ 0 ' : . C f i ^ L HCf.E PRINT*, ' FOREGROUND < 1 ) ' P R I N T * , ' B P 3 K 3 R O U N D ( £ ) ' PRINT*, ' CfiPNSE P P R P ^ . E T E ^ E ( 3 1 ' P R I N " * , ' RETURN ~Q ~iENL."4)' P R I N " * , 1 ' P R I N - ! ' * , ' ' W R I T E ( * , £ 1 0 ) £ 1 0 F O R M P T (' W - : P T WQU_D YC_ _!•<£ ~ G D O - » \ ) REPD <*, 1 1 0 ) N I F ( N.EO. 1 ) OP.L_ " O R O ^ I F ( N . E C . 2 ) C P . - L K ; 3 R 3 ; : B I F ( N . E C . 3 ) GO T C 90 I F (N.EC.4) GO TO 500 • 1 1 3 i r I N . c. . 1 > 1X=1 IF (N.EC.3) IY = 1 GQ TO £ 0 0 DD 404 I = i , 150 DO 40£ J = l , ISO F M B ( I , J ) = 0 . 0 COM"INUE CONTINUE DO 4 £ 0 1=:, ID I CD DO 410 J = l , 1 S T E P F M B ( I , J > = FOSE ( I, J ) - B A C K ( I , J ) CONTINJE CONTINJE GO TO 5 J C I Z = I X -i- IY IF (12. EC. £) GO TO 4<">n FORE (0, 0) =Fi_DST ( IDIOD; BACK (0, 0) =F^ .OA"" (IDIOD) FMB(0,0)=FLOAT(IDICD) FORE(0, 1)=FLOAT(I STEP) BACK(0, 1 ) =- L O A T IS~EP) FMBCO, 1 ) =i"LOOT ( ISTEP) F O R E ( 0 , £ ) = RA'v3E BOCK (0, £) =RANdE FMB (0, £) =RAN33 FORE(0,3)=PULSE BACK(0,3)= =>U_SE F M ? ( 0 , 3 ) = P J L S ~ DO 575 J = l , I D I C D FCRE <J,0) = IDN CJ) B A C K ( J , 0 ) = I D N ( J ) F M B ( J , 0 ) = I D N ( J ) CON" IN'JE RETURN END * * * * * * * * # # # # « * * * * * * * * * * * * * * * * * * * * * * * * * * • * * SUBROUTINE M P RC FF EXTERNAL. PD433P REAL FORE (0 : 50, 0: 150) , BACK CDs SO, C : I S O : , ( INTEGER*; SPECTA ( 4 f 3 3 ) , IDIO, IDIOP I N T E G E R » £ I D N ( 5 1 ) , I D N 3 ( 5 1 ) , I D I O D , I B ' t ^ , I S C N INTEGER*! I NTT COMMON FORE, BACK, FMB, IDIO, IDIOP, I N T COMMON / B _ l / IDN, IDICD, IE.TEP, ISCN, I P J u S E DO 4 1^1,50 DO £ J = l , I S O F O R E ( I , J ) = 0 . 0 CONTINUE CONTINUE Z = ( c L O a T : I S T E P ) * ( 0 . 5 ) ) *IPu_SE N=IN~(Z) DC 10 1=1,N CA^L T R S T i E C O N T NUE CALL HOME DC £ 0 0 J = l , IS~EP FORMAT(14) DO 115 K _ = l , I D I O D IDN2(KL)=IDN(KL) CONTINUE W R I T E ( * , 1 £ 0 > 'STEP ' , J , ' CF ' , I S T E P 1 1 4 DO 120 K =1,ISC\ CRLL PD436P(S3ECTR(0) , IDIOP) IP (K. GT. 1) GOTO 1£8 DO 126 M=l,3 DO 124 L=l, IDIOD IP (SPEOTft ( IDNi'(L) ) . i-T. :C~P ( I D V 2 C - > *2 , > II.'\.£ (_ ) = ID\2 • IF <SPECTP(IDN2<L>)._T.S-E"P!I3N£<_)-:)! I DN.: ( l. ) = I DN2 < L ) • 1£4 CONTINUE 12£ CONTINUE 1£B CONTINUE DC 140 I = : , IDIOD FQRE(I,J> = FORE(I,J) + FLOOT<S^ECTP(ID\UCI) >> 140 CONTINUE WRITE ;*, 110) K 130 CONTINUE DO 150 M=l , I PUt.BE CPUL TR5~G-150 CONTINUE CPUL HOME 200 CONTINUE Z =(FU3AT( I STEP; *0. 5)*IPU^SE N=I NT(Z) DO 300 1=1,N CP^L TRSTGB 300 CONTINUE DO 400 1 = 1, I D I O D DO 350 J = l , I S T E O F O R E ( I , J ) = ~ C R E ( I , J) / F L O P T ( I S O N ) 350 C O N T I N U E 400 C O N T I N U E R E T U R N E N D *********-*******^****************************-****** S U B R O U T I N E MPR3~B E X T E R N P U PD49£0 R E P L F O R E ( O : 50, O : 150) , B P C K (0 : 50, 0 : 150) , F M B (0 : 50, O : 1 5O I N T £ G E R * £ S3ECT<409£!,IDIO.IDIOP I N T E G E R * 2 I D N (51 ) , I D I O D , IS _E3, I S O N , I D U L S E , N, M, ;_, < I N _ E G E R * 1 I N - T COMMON F O R E , B P C K , ^MB, I D I O , I D I O P , I N T T COMMON / B _ l / I D N . I D I O D , IE~EP, I S O N , ! - — EE DO 4 1=1,50 DO c J=l,150 BPCK( I, J) =0. 0 £' CONTINUE 4 CONTINUE Z=(F^OP" (I STEP)« < 0. 5! )* IPuLEE N=I NT(Z) DO 10 1 = 1, N CP-L TR5TGE-10 CONTINUE CP-L HOvE DO 200 J=l,ISTE= 110 FCRMPT(I4) WRITE (», 120) 'STEP ' , J, ' OF ',ISTEP 120 FORMAT(P,13,P,12) DO 130 K = l , I SON CAi-L PD496P<S°ECT(0),IDIOP) 1 1 5 DO 140 1=1,IDIOD B R C K C , J) = B A C K ( I , J ) + F L O A T ( S - E C T r I D N ( I ) ) > 140 CONTINUE WRITE(*,110) K 130 CONTINUE DO 150 1*1=1, IPU-SE CA_L TRS~G-150 CONTINUE CPuL HO'rE 300 CONTINUE Z=(FUOPT(I STEP)»0.5)*I-U_SE N =I NT ( 2) DG 30i".) 1 = 1, N CA..L TRST3B 300 CONTINUE DC 400 1=1,IDIOD DO 350 J = l , I S T E 3 BOCK(I, J)=BROK ( I , J) /FLORT(ISCN) 350 CONTINUE 400 CONTINUE RETURN END SUBROUTINE R-DISO RER- F O R E ( 0 : 5 0 , 0 : 1 5 0 ) , B A C K ( 0 : 5 0 , 0 : 1 5 0 ) , F M B CO:50,0:150) INTEGER*£' IDIO, IDIOP I N^EGER*1 INTT COMMON FORE,BACK, FMB, IDIO, IDIOP, INTT CHRRPCTER*8 DFNRME, DISC*E, ^ I L . N P K * I 4 , TYPE*4 DISC='ft:' DG £ 1=0,50 DO 5 J=0,ISO F O R E ( I , J ) = 0 B P G K ( I , J ) = 0 F M B ( I . J ) = 0 5 CONTINUE £ CONTINUE WRITE <*, IO) 10 FORMRT('NAME 0- FI U E TO BE REfiD- '\> REPD(*,£0) D-NP^E 30 FORGOT(fi) PRINT*, ' ' PRINT*,' ' EC PR I N'T*, ' FOREGROUND ( 1 ) ' PRINT*, 'BACKGROUND <£> ' PRIN'*,'FOREGROUND - BACKGROUND(3)' PRINT*,'RETURN TQ K E \ u ( 4 ) ' PRIN T»,' ' PRINT*,' ' 30 WRITE(*,35) 35 FORMAT('SPECTRA TO BE REPD- '\> READ (*, 40) M 40 FORMAT(14) WRITE (*, 50) 50 FORMA -('NUMBER OF PRT0ME5- '\) READ(*,40) K WRITE(*,fcO) £0 FORMRT('NUMBER OF E'E-S- '\) RERD(*,40) L IF (M.EO.1> EO TO 100 I F (M.EC.£) GO TO £00 IF <M.EC.3) GO TD 300 IF (M. ED. 4) GO TO 3L>0 1 16 1 0 0 130 2 0 0 £ 3 0 3 0 0 3 3 0 5 O i j £ 0 0 9 0 0 10 £ 0 1 00 1 10 1 £ 0 1 30 195 bU i Li j,0 TYPE = ' . FGR' FILNAM=DISC//DFNAME//-YPE OPEN (3, F I L E = FI_NP'Yi) READ(3, 5 0 0 ) ( < F ORE <I, J ) , I = GO TO 6O0 TYPE=' . BGR' FILNAM=DISC//DFNAME//TYPE OPEN(3,FILE=FILNAM) READ(3,500) ( ( B A C K ( I , J ) , I = GO TO £ 0 0 ~YPE=' . FMB' FILNAM=DIS3//DFNAME//TYPE OPEN(3,FILE= _ILNAM) •O, K) , J = 0, L ) K ) , J = 0 , L ) R E A D ( 3 , 5 0 0 ) GO TO £ 0 0 FORMAT <8E10. C ^ O S E ( 3 ) C A L L HOME GO TO £ 5 RETURN END ( (Fiv-B ( I, J ) , 1=0, K: 4 ) J = 0. i *+ «*••»* S U B R O U T I N E 5 T 2 R E REA^ F O R E ( 0 : 5 0 , 0 : 1 5 0 ) , B A C K ( 0 : 5 0 , 0 : 1 5 0 ) , - M B ( 0 : 5 0 , 0 : 1 5 0 ) I N T E G E R * £ I D I O , I D I O P , I D N ( 5 1 ) , I D I O D , I S ' E P , I S C N , I P U _ S E I N T E G E R * 1 IN'T COMMON F O R E , B A C K , F M B , I D I O , I D I O " , I N T T C H A R A C T E R * 1 £ F N A M E , D F N A M E * 6 , T Y C E * 4 , D I S C * £ , F I LN A*-.* 1 4 , D A -I N T E G E R I L N , I R N , I R N 1 , I R N 3 , I R N 3 , I R N 4 , I R N 5 , I R N £ , I R N 7 , I R N B D I S C = ' A : ' W R I T E ( * , 10) FORMA"" (' F I L E N A M E - ' S) R E A D ( * , £ 0 ) DFNAME FORMAT(A) W R I T E ( * , 1 0 0 ) FORMAT('NUMBER OF P A T C H E S - '\) READ(*, 110) K F O R M A T ( 1 4 ) W R I T E ( * , 1 £ 0 ) E*;7.DES: NUMBER 10) L FOREGROUND(1) ' B A C K G R O U N D ( £ ) ' FOREGROUND - BACKGROUND(3) ' RETURN TO MENU ( 4 ) ' 40 0 FORMAT( READ(*, PRINT*, PRINT*, PRINT*, PRINT*, PRINT*, PRINT*, PRINT*, PRINT*, W R I T E ( * FORMAT < R E A D ( * , 1 1 0 ) I F ( N . E O . 1 ) (N. EO. £) (N. EO. 3) <N. EC. 4) TO 130 T Y P E = ' . FS<R' F I L N A M = D I S C / / D T N A M FNAME = F I L_NAM ( 3 : 1 4 ) O P E N ( 4 , F I L E = F I L N O " , S W R I T E ( 4 , 3 2 0 ) <(FORE( F O R M A T ( 6 E 1 0 . 4 ) GO TO 7 0 0 TYPE='.BGR' OF S T E P S - '\) I F I F I F GO £ 0 0 ) S P E C T R A N GO • GO GO GO TO BE STORED-TD 3 0 0 TO 4 0 0 TO S O C TO 9 O 0 / / T Y P E \ ) "ATUS^ = ' NEW ) 1=0, K) , J = 0 , L ) 1 1 7 h i L N H K = b l S U / / D F N A M t / / T Y l - t F N A M E = F I L N A M ( 2 : 1 4 ) • PEN (4, F I L E = T L N A M , STATUS=' NEW ) WRITE ( 4 , 330> < ( B A C K ( I , J ) , 1=0, K ) , J = 0, i_) GO TO 700 500 T Y P E = ' . F M B ' F I L N A M = D I S C // D F N A M E / / T Y P E F N A M E = F I L N A M ( 3 : 1 4 ) OPEN (4, FI'_E = F I L N A M , S T A T u S = ' NEW ) WRITE (4, 320) < < F M B ( I , J > , 1=0, K ) , J = 0 , L ) 700 C L . 0 S E ( 4 ) 5 0 0 CONTINUE E N D SUBROUTINE P_OT REA^ F O R E ( 0 : 5 0 , 0 : 1 5 0 ) , B f i C K ( 0 : 5 0 , 0 : 1 5 0 ) , F V B ( 0 : 5 0 , RERi_ DRTR (0 : 5 0 , 0 : 150) INTEGER*2 IDIO , IDIOP, PfiTC-iS, S T E P S , Z, IX, IY, IXR I N T E G E R * ! I NTT INTEGER* 4 IRDDR, IVA^*1 COMMON FORE, B f iCK ,FMB, I D I C , ICDICP , IN T T 5 C A ^ L H O M E P R I N T * , ' F O R E G R O U N D ( 1 ) ' P R I N T * , ' B A C K G R O U N D < £ > ' P R I N T * , ' F O R E G R O U N D - B A C K G R O U N D ( 3 ) ' P R I N T * , ' R E T U R N T O M E N U ( 4 ) ' P R I N T * , ' ' W R I T E (*, 10) 10 F O R M A T ( ' S P E C T R A TO B E P L C T I E D - ' \ ) R E A D ( * , £ 0 ) M £0 F O R M A T ( 1 4 ) W R I T E ( * , 3 0 ) 3 0 F O R M A T ( ' S C A _ E F A C T O R ( S - " O R E D / S C A _ E = R E S ^ L T ) '\) R E A D ( * , 4 0 ) S F 4 0 F O R M A T ( F 5 . £ ) I F <M.ED. 1) GO T O 1 0 0 I F ( M . E D . £ ) GO T O £ 0 0 I F ( M . E Q . 3 ) G C T O 3 0 0 I F ( M . E D . 4 ) G O T O 1 O 0 O GO TO 5 1 0 0 P A T C H S = N I N T ( F O R E ( 0 , 0 ) ) S T E P S = M N T ( F O R E ( 0 , 1 ) ) DO 1 £ 0 I = 0 , P A T C H S DO 1 1 0 J = 0, S T E P S D A T A ( I , J > = F O R E ( I , J ) / S ~ 1 1 0 C O N T I N U E 1 2 0 C O N T I N U E GO TO 4 0 0 £ 0 0 P A T C H S = N I N T ( B A C K ( 0 , 0 ) ) S T E P S = N I N T ( B A C K ( 0 , 1) ) DO £ £ 0 I = 0, P A T C H 3 DO £ 1 0 J = 0, B T E P S D A T A ( I , J ) = B A C K ( I , J ) / S F £ 1 0 C O N T I N U E 2 2 0 C O N T I N U E GO TO 4 0 0 2 0 0 P A T C H S = N I N T ( F i * B ( 0 , 0 ) ) S T E P S = N I N T ( F M B ( 0 , 1) ) DO 3 2 0 I = 0, P P T C - ' S DO 3 * 0 J = 0 , S T E P S 1 18 U H ; H ( 1 , J > = hl>ldU, J l / b>-3 1 0 C O N T I N U E 3 2 0 C O N T I N U E G O T O 4 0 0 4 0 0 C O L L H O M E P R I N T * , ' P L O T ( i ) ' P R I N T * , ' L I S T O N P R I N T E R ( £ > ' P R I N T * , ' R E T U R N T O M E N U ( 3 ) ' P R I N T * , ' ' W R I T E ( * , 4 1 0 ) 4 1 0 F O R M A T ( ' S E L E C T R N U M B E R ' \ ) R E R D ( * , £ 0 ) M I F ( M . E O . 1 ) G O T O 5 0 0 I F ( M . E O . 2 ) G O T O 600 I ~ ( M . E O . 3 ) G O T 0 1 0 0 0 I F ( M . G T . 3 ) G O _ C 40d 5 0 0 P R I N T * , ' T H E R R E R O F T H E P L O T T E R E X T E N D S - R O ^ X , Y = 0 , 0 ' P R I N T * , ' T O X , Y = 3 6 0 0 , £ £ 0 0 ' W R I T E ( * , 5 1 0 ) 5 1 0 F O R M A T ( ' I N P U T T H E S T A R T O F P L O T X C O C R 0 I N P ~ E '\> R E R D ( * , 5 £ 0 ) I X 5 E 0 F O R M A T ( 1 4 ) W R I T E ( * , 5 £ 5 ) 5 2 5 F O R M A T ( ' I N P U T Y C O O R D I N A T E ' \ ) R E A D ( * , 5 £ 0 ) I Y W R I T E ( * , 5 3 0 ) 5 3 0 F O R M A T ( ' P A T C H T O B E P L O T T E D ' \ ) R E A D ( * , 5 4 0 ) IP 5 4 0 F O R M A T ( I E ) D M A X = D A T A ( I P , 1 ) D O 5 5 0 J = £ , S T E P S I F ( D A T A ( I P , J ) . G T . D M A X ) D M A X = D A ~ A ( I P , J > 550 C O N T I N U E W R I T E ( * , 5 £ 0 ) D M A X 5 6 0 F O R M A T ( ' T H E M A X I M U 1 * " I S ' , F 1 0 . 3 ) S C = ( £ 6 0 0 . O - I Y ) / D M A X W R I T E ( * , 5 7 0 ) S C 5 7 0 F O R M A T ( ' T O F I T Pi_OT M U S T S C A L E B Y ' , F 1 0 . 5 ) P R I N T * , ' A U T O S C A L E ( 1 ) ' P R I N T * , ' Y D U R C H O I C E ( £ ) ' P R I N T * , ' N O S C P 1 _ E ( 3 ) ' W R I T E !*,5a0) 5 6 0 F O R M A T ( ' S E L E C T A N U M B E R '\> R E A D ( * , 5 9 0 ) M 5 9 0 F O R M A T ( I I ) G O T O ( 6 4 0 , £ 1 0 , 6 0 0 ) , M 6 0 0 S C = 1 . 0 G O T O 6 4 0 6 1 0 W R I T E ( * , 6 2 0 ) 6£0 F O R M A T ( ' Y O U R C H O I C E O F S C A L I N G F A C T O R I S ' \ ) R E A D ( * , £ 3 0 ) S C 6 3 0 F O R M A " ( F 1 0 . 5 ) 6 4 0 W R I T E ( * , 6 5 0 ) S C 6 5 0 F O R M A T ( ' S C A L I N G F A C T O R I S ' , F 1 0 . 5 ) W R I T E ( * , 6 6 0 ) £ 6 0 F O R M A T ' X A X I S S C A L I N G F A C T O R ( 1 T O 5 ) '\> R E A D ( * , 6 7 0 ) I X A £ 7 0 F O R M A T ( I I ) 1 19 IADDR = *F9CDB I VOL = *00 COLL POKE ( IADDR, I V A L . ) IADDR = *~9D0F I VOL = $00 COLL POKE (IODDR, I VOL) OPEN(6,FILE='L5T:',STATUS='NEW 1> WRITE (6, 700) ' -'• 700 FORMAT(fi) WRITE(£, 710) 'M' , IX, ' , ' , IV 710 FORMAT(fi, 14, O, 14) IX = 0 I Y = INT ( D f i T f l ( I P , 1)*SC) WRITE(£,710)'I',IX,',',IY DC 750 J = 2, STEPS I X = IXO IY = IN'T ( (DOTO ( I P, J) - DOTO ( I P, J - 1 > ) WRITE ( 6 , 7 1 0 ) ' I' , 0, ' , ' , IY WRITE (£,710)'I',IX,',',0 750 CONTINUE WRITE(£,700)'H' CLOSE(£) IODDR = S _9CDB IVO_ = *04 COLL POKE(IODDR,IVAL) IfiDDR = «F9D0-I VOL = *04 Cf i - L POKE (IODDR,IVP_> GO TO 400 * PRINTING "HE DOTO * 800 OPEN (6, F I _ E = ' L S ~ : ' , S Tfi- rUS = ' NEW' ) 805 PRINT*, 'GIVE STORT AND END 0" DU^P ' WRITE(*,810) e i O FORMAT('STORT - '\) REOD(*,820)K 820 FOR vOT(14) WRITE(*,830) 630 FORMAT(' END - '\) REOD <*,820)L WRITE(*,850) e50 FORMAT('PATCH NUMBER -'\> READ <*, 860) IP 860 FORMAT (12) IF ( K . L T . O ) GO TO 805 IF(K.GT.STEPS) G O TO 805 I F ( L . L T . K ) GC TO 805 I F ( L . G T . S T E P S ) GO TO 805 I F U P . L T . O ) GO TO 805 IF ( I P. GT. PATCHS) G C T Q g'05 865 PRINT*,' ' PRINT*, ' ' PRINT*,'DUMP TO SCREEN ( 1 ) ' PRINT*, ' DUMP TO PRINTER ( 2 ) ' WRITE(*,870) 870 FORMAT('DESTINATION DF DUMP -'\> READ(*,880) N 880 FORMAT(II) 1 2 0 IF (N.EO. 1) GO TO 890 IF (N. EO. £') GO TO 900 GO TO 865 830 Z = 0 GO TO 910 900 Z = 6 310 WRITE(Z,9E0) 3E'0 FORMAT (' DATA' ) DO 350 I = K,L WRITE < Z, 930) I , D A T A(IP, I ) 330 FORMATl I A , C I S . 4) 350 CONTINUE IF (Z.ED.6) GO TO 360 WRITE(*,360) 360 FORMAT('INPUT INTEGER TO C O N T I N U E '\! READ <*,970)M 970 FORMAT(IE) 330 CLOSE(6) GO TO 400 1000 RETURN END SUBROUTINE INTTIM REAL FO R E ( 0 : 5 0 , 0 : 1 5 0 ) , B A C K ( 0 : 5 0 , O : 1 5 0 ) , F M B ( 0 : 5 0 , 0 : 1 5 0 ) INTEGER*E I D I O , I D I O P INTEGER*1 I NTT COMMON FORE,BACK,FMB, IDIO, IDIO-, I NTT EXTERNAL STATUS INTEGER*4 IADDR IN'E3ER*1 IV P L IVAL=S04 I A D D R = * P F 0 0 1 7 CALL POKE<IADDR,IVA^> IADDR= * F - 0 0 1 3 CALL HOME IF (INTT.LT.O) JVQ_=-1-INTT IF ( I NTT. GE. 0) JVA_=£55-INTT WRITE(»,110) 'INT TIME=',JVA_ 10 CALL STATUS I X=I P E E K ( * F F 0 0 F C ) C HEX OB TO INCREASE AND HEX 16 TO DECREASE IF (IX.EQ.*OB) GO TC 100 IF (IX.EQ.S16) GO TO £00 GO TO 900 100 I F ( J V A L . E C . £ 5 5 ) GO TO 105 INTT=I NTT—1 PRINT*, I NTT IF (INTT.LT.O) J V A _ = - 1 - I N T T IF (INTT.GE.O) JVA_=£55-INTT IVAL=IN"TT CALL POKE(IADDR,IVAu) 105 CALL HOME WRITE<*,110) 'INT TIME=',JVA^ 1 10 FORMAT(A3, 13) GO TO 10 300 I F (JVAL.EO.1) GO TO 105 INTT=INTT+1 PRINT*, I NT •121 i h U N I I. L I . O) JVAL=-1-INT1 IF (INTT.GE.O) JVAL=£55-INTT IVAL=INTT COLL POKE ( IADDR, IVAL) GO TO 105 900 RETURN END SUBROUTINE TRSTG INTEGER*4 I PiDDR I NTEGER*1 IVAL 10 PRINT*, 'MOVE FOREWORD(1)' PRINT*,'MOVE BACK<£)' PRINT*, ' RETURN TO MENU ( 3 ) ' PRINT*,' ' PRINT*,' ' 90 WRITE(*,100) 100 FORMAT (' WHAT WOULD YOU L I K E TO D C - '\) READ(*,110) K I F (K. EQ. 3) GO TO 900 110 FORMAT(14) PRINT*,' ' PRINT*,' ' WRITE (*, 120) 120 FORMAT('HOW MANY MM- '\) READ(*,115) RMM IPULSE=I NT(RMM/.0127) 115 FORMAT(F5.1) IADDR=*FF0017 IVAL=*00 CALL POKE(IADDR,IVAL) IF (K.ED.1) GO TO £00 IF (K.EQ.2) GO TO 300 GO TO 90 £00 IADDR=*FF001£ DO £30 1=1,IPU^SE IVAL=*FD CALL POKE<IADDR,IVAL) CA_L DEi_AY IVAL=*FF CALL POKE(IADDR,IVAL) CALL DELAY £30 CONTINUE CALL HOME IVAL=404 IADDR=»FF0017 CALL POKE(IADDR, IVA_ > GO TO IO 300 IADDR=»FF001£ DO 330 1 = 1, I PULSE IVAL=*FE CALL POKEdADDR, IVAL) CALL DELAY IVAL=*FF CALL POKE(IADDR,IVAL) CALL DELAY 330 CONTINUE CALL HOME IVAL=«04 IADDR=*FF0017 CALL POKE(IADDR,IVAL) GO TO IO 900 RETURN END SUBROUTINE DELAY 1 22 DU l i U 1 = 1,3 D=(£. 303)*FL0fiT(I) £0 CONTINUE RETURN END ******************************************* SUBROUTINE TRSTGB INTEGER** I PiDDR INTEGER*1 IVfiL IfiDDR=SFF0017 IVPL=*00 COLL POKE<IfiDDR,IVfiL) IfiDDR=*FF001£ IVfiL=*FE CfiLL POKE(IPDDR,IVfiL) CfiLL DELOY IVfi,_=*FF CfiLL POKE(IfiDDR,IVfiL) CfiLL DELfiY IVfiL=*04 IfiDDR=*FF0017 CfiLL POKE(IfiDDR,IVfiL) RETURN END ************************************************* SUBROUTINE TRSTGF INTEGER** IfiDDR INTEGER*! IVfiL IfiDDR=*FF0017 IVPL=$00 CfiLL POKE(IfiDDR,IVfiL) IfiDDR=*FF001£ IVftL=*FD CfiLL POKE(IfiDDR,IVfiL) CfiLL DELfiY IVRL=*FF COLL POKE(IfiDDR,IVfiL) CfiLL DELfiY IfiDDR=*FF0017 IVfiL=*04 CfiLL POKE(IfiDDR,IVfiL) RETURN END 123 APPENDIX B Fe s p e c t r a c o l l e c t e d a t an r f i n p u t power of 1.25 kW and a v e r t i c a l h e i g h t of 16 mm above t h e l o a d c o i l a r e p r e s e n t e d i n p a r t s A,B,C,D,E,F,G and H. The w a v e l e n g t h r a n g e o f e a c h s p e c t r u m and t h e e m i s s i o n l i n e s c o n t a i n e d w i t h i n a r e l i s t e d i n the f o l l o w i n g t a b l e . In o r d e r t o see weak, h i g h e n e r g y l i n e s , the i n t e n s i t y a x i s have been expanded by t h e a p p r o p i a t e s c a l e f a c t o r . P a r t W a v e l e n g t h Range (nm) F e l L i n e F e l l L i n e S c a l e F a c t o r A 242.80 - 267.10 256.25 6.0 258.59 259.84 259.94 260.71 261.19 261.38 261.76 262.57 262.83 B 242.80 - 267.10 256.35 60.0 256.69 258.26 259.15 262.17 266.47 266.66 C 267.30 - 290.80 271.44 6.0 272.75 273.96 274.32 274.65 275.33 124 P a r t W a v e l e n g t h Range (nm) F e l L i n e F e l l L i n e S c a l e F a c t o r D 267.30 - 290.80 273.07 60.0 275.57 276. 18 E 343.30 - 367.10 356.54 2.0 357.01 358.12 360.89 361.88 F 343.30 - 367.30 355.37 30.0 360.55 360.67 365.15 G 367.10 - 391.00 371.99 2.0 373.49 373.71 374.95 381.58 382.04 382.59 382.78 385.99 388.63 H 367.10 - 391.00 368.22 30.0 376.55 388.85 125 X* 00 o 2 931 E 2 5 6 . 2 5 2 6 1 . 7 6 261.38 258.59 259.84 260.71 259.94 261.19 262.57 262.83 > CQ 9 9 - 9 9 2 L*'99Z J 2 88*19€ 68'09E-21 * 9SC to*z.se-1 30 »9*9SE-_4 i z o m T 1 3 3 APPENDIX C Ba s p e c t r a c o l l e c t e d a t an r f i n p u t power of 1.25 kW and a v e r t i c a l h e i g h t of 16 mm above t h e l o a d c o i l a r e p r e s e n t e d i n p a r t s A,B,C,D,E and F. The w a v e l e n g t h r a n g e o f e a c h s p e c t r u m and the e m i s s i o n l i n e s c o n t a i n e d w i t h i n a r e l i s t e d i n t h e f o l l o w i n g t a b l e . In o r d e r t o see weak, h i g h e n e r g y l i n e s , t h e s p e c t r a have been expanded by t h e a p p r o p i a t e s c a l e f a c t o r . P a r t W a v e l e n g t h Range (nm) B a l L i n e B a l l L i n e S c a l e F a c t o r A 257.40 - 281.60 263.48 150.0 277.14 B 388.20 - 412.10 393.57 389.18 125.0 399.34 C 412.10 - 435.03 428.31 413.07 125.0 435.03 416.60 D 448.65 - 472.50 452.49 1.0 455.40 E 472.30 - 495.10 490.00 1.0 493.41 F 575.90 - 597.50 577.76 585.37 150.0 582.63 590.76 597. 17 1 34 LZ I K J 8 E I oo 2 2 z o r 4 • 1 39 APPENDIX D Cr s p e c t r a c o l l e c t e d a t an r f i n p u t power of 1.25 kW and a v e r t i c a l h e i g h t of 16 mm above t h e l o a d c o i l a r e p r e s e n t e d i n p a r t s A,B,C,D,E and F. The w a v e l e n g t h r a n g e of e a c h s p e c t r u m and the e m i s s i o n l i n e s c o n t a i n e d w i t h i n a r e l i s t e d i n t h e f o l l o w i n g t a b l e . In o r d e r t o see weak, h i g h e n e r g y l i n e s , t h e s p e c t r a have been expanded by t h e a p p r o p i a t e s c a l e f a c t o r . P a r t W a v e l e n g t h Range (nm) C r I L i n e C r I I L i n e S c a l e F a c t o r A 245.80 - 270.10 265.36 1.0 265.86 266.60 B 269.60 - 294.70 284.98 1.0 286.26 287.04 C 269.60 - 294.70 272.65 277.81 100.0 2 7 3 . 1 9 292.71 276.99 290.91 D 285.00 - 309.20 297.55 297.19 3.0 299.66 297.97 300.09 304.09 300.51 305.01 302 . 1 6 302.44 305.39 E 309.30 - 333.30 311.87 0.75 312.04 318.07 323.41 141 P a r t W a v e l e n g t h Range (nm) C r I L i n e C r I I L i n e S c a l e F a c t o r F 421.10 - 444.60 425.44 427.48 428.97 434.45 435 . 1 8 1 42 t o -U bo o Z 2 2 6 6 . 4T ON CN 1 44 66'9LZ 1 4 5 NJ 8fr I o Z 4 2 5 . 4 4 4 2 7 . 4 8 4 2 8 . 9 7 4 3 4 . 4 5 4 3 5 . 1 8 o Z 2 

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