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An infrared study of D₂O and H₂O inert matrices Shurvell, Herbert F. 1962

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AN INFRARED STUDY OP D 0 2  AND  H 0 IN INERT MATRICES 2  by HERBERT P. SHTJRVELL B.Sc.  EXETER, 1 9 5 9 .  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER  OF  SCIENCE  i n the 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 April 1962.  In presenting  t h i s thesis i n p a r t i a l f u l f i l m e n t of  the requirements f o r an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available f o r reference and study.  I further agree that permission  for extensive copying of t h i s thesis f o r scholarly purposes may granted by the Head of my Department or by his  be  representatives.  It i s understood that copying or publication of t h i s thesis f o r f i n a n c i a l gain s h a l l not be allowed without my written permission.  Department The University of B r i t i s h Columbia, Vancouver 8, Canada. Date  ftPrtlL  (ii)  A B S T R A C T  I n f r a r e d s p e c t r a of and D2O trapped i n s o l i d argon, krypton and n i t r o g e n have been o b t a i n e d a t IL°K. In a d d i t i o n , s p e c t r a have been r e c o r d e d of D2O i n carbon t e t r a c h l o r i d e and ammonia m a t r i c e s a t 77°K, and of a d i l u t e s o l u t i o n of D2O i n carbon t e t r a c h l o r i d e a t 25°C. D i l u t i o n s t u d i e s i n v o l v i n g changing the m a t r i x to water r a t i o from $0 to 500 have been c a r r i e d out with DpO i n argon a t i|_ K. Changes i n the s p e c t r a of D2O ana H2O i n argon, k r y p t o n and n i t r o g e n m a t r i c e s during warm-up have been observed. The d i l u t i o n and warm-up s t u d i e s have made i t p o s s i b l e to a s s i g n c e r t a i n peaks to monomer, low polymer and h i g h e r polymers. 0  The complex s p e c t r a of H2O and D2O i n argon, krypton and n i t r o g e n a t l i q u i d helium ..temperatures are d i s c u s s e d , and p r e v i o u s simple e x p l a n a t i o n s i n v o l v i n g m o l e c u l a r a s s o c i a t i o n , r o t a t i o n and mult i p l e t r a p p i n g s i t e s advanced by other workers are shown to be inadequate. . C o n s i d e r a t i o n i s g i v e n to the i s o t o p e e f f e c t and i n t e r a c t i o n s w i t h the matrix i n an attempt to account f o r the observed s p e c t r a .  (i)  ACKNOWLEDGMENT  I would l i k e to express my g r a t i t u d e t o Dr. K. B. Harvey f o r h i s h e l p during  and-encouragement  the course of t h i s ?<?ork.  Thanks are  a l s o due to Mr. R. Muehlchen f o r h i s help  with  the apparatus and making the l i q u i d helium; a l s o to Mr. P. Horn who r a n mass s p e c t r a on the m a t e r i a l s used.  (iii) CONTENTS Page Acknowledgment  i  Abstract  ii  L i s t o f Tables  V  L i s t of Figures  vi  Chapter  Chapter  Chapter  1  Introduction  1  1-1  The  1  1-2  Summary o f Previous Work  1  1-3  An O u t l i n e o f the Present Work  2  2  Experimental  6  2-1  Techniques Employed  6  2-2  The Low Temperature  2-3  Materials  8  2-k  The  8  3  Results  10  3-1  D0  10  3-2  D i l u t i o n S t u d i e s on D 0 i n Argon  10  3-3  Warm-up S t u d i e s  13  3-k  D 0  i n V a r i o u s M a t r i c e s @ 77°K  13  3-5  D0  i n Carbon t e t r a c h l o r i d e  114-  3-6  H0  i n Various M a t r i c e s @ i|°K  1k  Chapter Ij. k-1  2  Problem  6  Cell  Spectrometer  i n Various M a t r i c e s @ ifOK 2  2  2  2  Discussion Assignments t o Polymeric  33 Species  33  (iv)  CONTENTS Page Li-2  Isotope E f f e c t s  I4-—3  M u l t i p l e Trapping S i t e s  lilx  JL|_— JLj_  R o t a t i o n of Monomer  52  LL-5  I n t e r a c t i o n s w i t h the M a t r i x  56  IL-6  Conclusions  59  J4.-7  Suggestions  Appendix I Appendix I I Bibliography  f o r F u r t h e r Work  i\2  59  P r o p e r t i e s and C h a r a c t e r i s t i c s o f Matrices  60  Symmetry P r o p e r t i e s , S e l e c t i o n Rules and Energy L e v e l s o f HgO and  63 66  (v) L I S T OF TABLES• Page TABLE 1 2 3  Van T h i e l e t a l - H 0  i n N i t r o g e n a t 20°K„  2  P r e v i o u s S p e c t r a o f HgO a n d Gas M a t r i c e s  i n Rare  3 II  -A Summary o f I n f r a r e d S t u d i e s o f H 0 a n d 2  D2O b y t h e M a t r i x I s o l a t i o n T e c h n i q u e i n Various Matrices at  5 11  if.  S p e c t r a o f D2O  5  D i l u t i o n S t u d i e s - D2O i n A r g o n  12  6  H2O i n A r g o n , K r y p t o n  16  7  A s s i g n m e n t s t o H2O P o l y m e r s  38  8  A s s i g n m e n t s t o D2O P o l y m e r s  ill  9  Peaks A s s i g n e d  and N i t r o g e n a t L\PK  t o Monomer i n S p e c t r a o f  k$  D2O a n d H2O 10  Diameters o f L a t t i c e S i t e s  11  S t r o n g e s t Monomer P e a k s i n S p e c t r a o f D 0 and H 0 2  12  l\h  2  D2O a n d H2O a t  IL°K  -  lp3  Allowed Transitions  and C a l c u l a t e d I n t e n s i t i e s  .  53  13  Calculated Frequencies  lit  Physical Properties of Matrices  61  15  E n e r g y L e v e l s o f H2O a n d D 0  65  f o r t h e ArOD^ m o l e c u l e s  2  $8  (vi)  LIST OF FIGURES To F o l l o w Page F i g . 1(a) (h)  The Low  Temperature  Cell  The Apparatus - Vacuum System and Low Temperature C e l l  SPECTRA: F i g s . 2-k  D i l u t i o n Studies - D 0 2  i n Argon a t  4°K F i g s . 5-7  DpO  17 i n Argon, Krypton and N i t r o g e n  at l+°K F i g s . 8-10  HpO tt  i n Argon,  Krypton and N i t r o g e n 25  k°K  F i g . 11  A Warm-up Study - D 0  F i g . 12(a)  D 0  i n C C l ^ M a t r i x a t 77°K  (b)  D 0  i n CCl^ Solution @  2  F i g . 13(a) (b)  2  2  21  i n Krypton  29 31  2S°G ip9  The Water Molecule The Normal V i b r a t i o n s of the Water .Molecule  Fig. l k  S t r u c t u r e s of S o l i d M a t r i c e s  F i g . 15  The Normal V i b r a t i o n s of an X Y Z .Molecule  2  $6  1. CHAPTER 1. 1-1  INTRODUCTION  The Problem. I n f r a r e d spectroscopy o f water i n gas, l i q u i d , and  s o l i d phases, has been the s u b j e c t of e x t e n s i v e r e s e a r c h by many workers.  The v e r y complex gas phase s p e c t r a o f  both H£0 and D£0 have been completely a n a l y s e d (1) - ( k ) . The  gross f e a t u r e s o f the l i q u i d phase spectrum  and e a s i l y i n t e r p r e t e d  (5) -  a r e simple  ( 8 ) , and that o f the s o l i d  phase, although e x h i b i t i n g s e v e r a l i n t e r e s t i n g f e a t u r e s , has been e x p l a i n e d (9) ( 1 0 )  (11).  More r e c e n t work ( 1 2 ) . - . ( 1 5 ) has suggested molecules  t h a t water  trapped i n s o l i d i n e r t m a t r i c e s a t low  possess unexpected  temperatures  p r o p e r t i e s which m a n i f e s t themselves i n  complex i n f r a r e d s p e c t r a .  The problem i s then to supplement  e x i s t i n g data, by o b t a i n i n g s p e c t r a f o r r e g i o n s h i t h e r t o unexamined by the m a t r i x i s o l a t i o n technique, to c o n f i r m and improve p r e v i o u s work by r e p e a t i n g under h i g h e r r e s o l u t i o n , and  to f i n d a s a t i s f a c t o r y e x p l a n a t i o n f o r the observed s p e c t r a .  1-2  Summary of P r e v i o u s Work. Van  Thiel,Becker & Pimentel  n i t r o g e n m a t r i x a t 20°K.  (12) studied H 0 i n a 2  By v a r y i n g the m a t r i x to water r a t i o  from 10 to 1 0 0 0 , they a s s i g n e d f r e q u e n c i e s t o water monomers, dimers,  and h i g h e r polymers.  Catalano and M i l l i g a n and D 6 2  (See Table  1).  ( l k ) have r e c o r d e d s p e c t r a o f H 0 2  i n argon, krypton and xenon i n the temperature  20 - k.2°K.  These workers observed  several closely  range  spaced  2  bands I n t h e b e n d i n g their results argon,  I I ) , and i n t e r p r e t e d  and D 0  on t h e b a s i s t h a t  rotate i n solid  2  k r y p t o n and xenon. Glassel  para H 0  (13)  i n argon  2  that  r e g i o n (see Table  the spectrum  a mixture  has s t u d i e d the spectrum and x e n o n m a t r i c e s closely  of ortho  a t 20°K,  and  and  concluded  a p p r o x i m a t e s t h e gas s p e c t r u m para H 0  o f 1$% o r t h o a n d  a t 20°K.  2  (15)  repeated  t h e work w i t h H 0  _|i°K, and s u g g e s t e d  rotation  i n multiple trapping sites  Ogilvie  possible  1-3  2  i n argon a t  An O u t l i n e o f t h e P r e s e n t most s i g n i f i c a n t  Work.  results  described i n this  a r e t h e s p e c t r a o b t a i n e d a t lt°K f o r D 2 0 i n a r g o n , n i t r o g e n , and f o r H 0 2  results  i n krypton.  supplement e x i s t i n g  P r e v i o u s workers used record their  spectra;  work i n H 0 2  krypton  The way i n w h i c h  double  these  beam p r i s m i n s t r u m e n t s  the spectrometer  I t was d e c i d e d ,  thesis  d a t a i s shown i n T a b l e I I I .  a s i n g l e beam g r a t i n g i n s t r u m e n t lution.  as a  explanation of h i s results.  The  and  of  capable  used  i n t h i s work  to was  of very high reso-  t h e r e f o r e , to repeat  the p r e v i o u s  i n n i t r o g e n and k r y p t o n .  In d i s c u s s i n g the complexity  o f the observed  the f o l l o w i n g p o i n t s n e e d t o be c o n s i d e r e d : (a) p o l y m e r i c  species,  (b) m u l t i p l e t r a p p i n g  sites,  (c) r o t a t i o n o f t h e w a t e r monomer, (d) i n t e r a c t i o n s w i t h  the m a t r i x .  spectra,  3  TABLE 1.  Band cm"'  The Work o f Van T h i e l e t a l ( 1 2 ) Observed I n f r a r e d Suectrum of H£0 i n N i t r o g e n a t 20°K.  Probable Species  Band Width y% cm-'  Frequency S h i f t -«-(y -v 0  ) cm-'  1600 l6l5 1620 1633  monomer  5  -  dimer polymer  _  _  35  —  3355  polymers  3222 3318  _  365  320  tetramer (?)  80  -  kSk 358  3355 3510  t r i m e r (?)  32  -  311 166  351|-6 3691  dimer  23 27  130 -15  3627 3725  monomer  20 25  _  Uo  - 3676cm"  i s the average of the monomer peaks (3627 and 3725 cm-' )  P r e v i o u s S p e c t r a o f H2O and D 0 i n Rare Gfas M a t r i c e s .  TABLE I I .  (a)  2  Bending Region ( V 2  ) f r e q u e n c i e s i n om'  Catalano & M i l l i g a n ( l k ) D0 M/R = 800 i n Argon i n Argon 2  lift 1163 1178 1190 1195 1203 1213 1220 1260  Ogilvie(15)  H 0 ::-M/R . 500 i n Krypton  H 0 M/R - 300 i n Argon 2  2  i n Xenon  1557 1572 1593  1572 1590  1560 1585  1608  1605  1602  1622 1638 1655  1620 1630 164.O  1615 1628 161+2  157k 1593 1602 1608 1610 l62k 163? 1663  -::-M/R means m a t r i x to water r a t i o .  (b)  S t r e t c h i n g Region ( V , & 1?  ) o f H 0---;:- f r e q u e n c i e s i n cm"' . 2  3  Glasel (13)  Catalano & M i l l i g a n ( l k ) M/R  unknown  i n Argon  i n Krypton  M/R i n Argon  3508 3636 3659-20 3730*20 3772120  3750*20  3689 372k 37k8 3768  =600  Ogilvie (15) M/R  =  300  i n Xenon  i n Argon  3327  3376 3396 3kl6 3510 357k 3633.5 3651 3695 3708 3725 3757.5 3777  3521 3539 3582 3613 3686 3737 3758  -::--::-There have been no p r e v i o u s m a t r i x i s o l a t i o n s t u d i e s on D 0 i n this region. 2  5 TABLE I I I .  A Summary o f the I n f r a r e d S t u d i e s o f H2O & D 0 by the M a t r i x I s o l a t i o n Technique I n c l u d i n g the Present Work. The Instruments Used by the Various Workers are Given. 2  H 0  D 0  2  Matrix  Nitroger  Argon  Bending region  2  Stretching region  Van T h i e l e t a l ( 1 2 ) ( P e r k i n Elmer 2 1 )  Catalano & M i l l i g a n (Ik) (P.E. 2 1 & 112 prism)  Glasel (13) (Beckmann D.K.I)  Krypton  Catalano & Milligan  THIS WORK  Xenon  Catalano & Milligan  Glasel  Bending region  Stretching region  THIS WORK ( P e r k i n Elmer 112 g r a t i n g )  Catalano & Milligan  THIS WORK  THIS WORK  -  * I n the present work H 0 i n n i t r o g e n has been repeated. 2  O g i l v i e ( 1 5 ) has repeated the work w i t h HoO i n argon, u s i n g the P e r k i n Elmer 1 1 2 G r a t i n g Instrument.  6.  CHAPTER 2. 2-1  EXPERIMENTAL  Techniques  Employed;  Water m o l e c u l e s were t r a p p e d i n i n e r t m a t r i c e s a t temperatures u s i n g  t h e m a t r i x i s o l a t i o n method d e s c r i b e d  B e c k e r and P i m e n t e l ( l 6 ) , W h i t t l e , Bass  low  and B r o i d a (18).  The  of  a chemically active  in  a large  Dows and P i m e n t e l (17)  technique c o n s i s t s o f the  and  dispersal  c a s e D2O o r H2O -  substance - i n t h i s  e x c e s s o f an i n e r t  by  s o l i d matrix at a  temperature  low enough t o p r e v e n t d i f f u s i o n o f t h e a c t i v e m o l e c u l e s . I t may  be n o t e d t h a t w a t e r  "reacts"  to form dimers  Mixtures several  of water  or polymers vapour  g a s e s was  and  m i x t u r e was  on a c a e s i u m  where t h e gas  iodide plate  s t r e a m was  c o o l e d by  l i q u i d n i t r o g e n t o 77°K.)  c o n t r o l g a s - f l o w and  2-2  o f the s t o r a g e b u l b .  The t y p e , and  low  impinge  rate  used  o f f l o w was gauge.  to  indicated  (See f i g . l b )  Cell: (19)  u s e d f o r t h i s work i s o f t h e D u e r i g - M a d o r  i s shown i n f i g .  la.  central l i q u i d helium container shield,  allowed to  A n e e d l e v a l v e was  the r e l a t i v e  Temperature  cell  During a run  l i q u i d h e l i u m t o k. 2°K  the p r e s s u r e r e a d i n g of a thermocouple The Low  produced  p a s s e d through a d e p o s i t i o n tube i n t o the  cell  of  Thorough m i x i n g o f the  a c h i e v e d by means o f a c o n v e c t i o n c u r r e n t  temperature  by  bonding.  m a t r i x to water r a t i o s  3 0 0 - t o - l were u s e d .  by h e a t i n g t h e l o w e r p a r t  (or  by hydrogen  since i t  w i t h a m a t r i x gas were p r e p a r e d  days b e f o r e an e x p e r i m e n t ;  b e t w e e n 200  the  i s considered active  and an o u t e r v e s s e l  I t consists  essentially  s u r r o u n d e d by a  of a  radiation  e q u i p p e d w i t h o p t i c a l windows o f  fig  la.  THE  LOW  TEMPERATURE  CELL  .liquid helium  liquid _ nitrogen  to  WWA/  pumping system  A/vWA  radiation^ shield  Cs I  hole to admit infrared beam  deposition window  hole to admit gas from d e p o s i t i o n t u b e  deposition Cs I  windo w  tube  7.  caesium of  iodide.  The  cell  i s c o n n e c t e d t o a vacuum  the c o n v e n t i o n a l t y p e . The  suspended with  l i q u i d helium container  i s made o f c o p p e r and i s  by  i n f l o w o f h e a t by c o n d u c t i o n ,  the neck t o m i n i m i z e  subsequent  ( a l s o copper) as l i q u i d helium  loss  c a n be  nitrogen.  container  of l i q u i d helium. filled  i s a caesium  as a t r a c e giving  90°  thermocouple  on t h e same c h a r t p a p e r  observed. The  so t h a t  deposition  This  iodide plate  First, nitrogen, the  t a k e s a b o u t 30 m i n u t e s .  until  to minimize the c o n t a i n e r  deposited u n t i l infrared  thus  spectrum  t h e low  either  the  vessel.  temperature  shield  is filled  with  liquid  slowly  to  cool  This usually requires  1% l i t r e s  A more r a p i d  of  transfer  is filled  (1 l i t r e ) .  o f condensed  study i s produced.  The  material  T h i s may  and  liquid  l o s s by e v a p o r a t i o n i s then c a r r i e d  a film  cell  follows:-  the r a d i a t i o n  to k . 2 ° K .  i s recorded  turned through  can f a c e  then l i q u i d h e l i u m i s t r a n s f e r r e d  container  helium  be  t u b e o r t h e windows o f t h e o u t e r  a t y p i c a l r u n i s as  the  u s e f u l f o r warm-up  l i q u i d h e l i u m c o n t a i n e r may  the caesium  liquid  i s a t t a c h e d to the  a t w h i c h the  is particularly  such  junction of a  as t h e s p e c t r u m  o f the temperature  The p r o c e d u r e f o r o p e r a t i n g in  cold  The E.M.P. f r o m the t h e r m o c o u p l e  a record  studies.  i o d i d e window on w h i c h The  shield  refrigerant  S e t i n a copper b l o c k below the  gold-silver/gold-cobalt copper b l o c k .  The r a d i a t i o n  with a l i q u i d  d e p o s i t o f D^O/matrix forms.  was  system  out  gas m i x t u r e i s suitable for  take s e v e r a l hours,  8. depending on the r a t e o f d e p o s i t i o n and i t i s f r e q u e n t l y necessary t o make a second t r a n s f e r o f l i q u i d h e l i u m and a f u r t h e r d e p o s i t i n o r d e r to o b t a i n s a t i s f a c t o r y  spectra.  When d e p o s i t i o n i s complete the caesium i o d i d e p l a t e i s turned through 9 0 ° * i d the a p p r o p r i a t e r e g i o n s o f the spectrum a  are  scanned.  2-3  Materials: Regular grade argon and p r e p u r i f i e d n i t r o g e n were o b t a i n e d  from Matheson Co., Inc., and neon and k r y p t o n from A i r Reduction Co.  Mass s p e c t r o s c o p i c analyses o f these gases i n d i c a t e d an  upper l i m i t of i m p u r i t y f o r the argon and n i t r o g e n o f 5 - 1 0 p a r t s p e r m i l l i o n , and 5 0 - 6 0 p a r t s p e r m i l l i o n f o r the neon and k r y p t o n .  D 0 o f 9 9 . 8 $ p u r i t y and double d i s t i l l e d H 0 2  2  were t r e a t e d by r e p e a t e d f r e e z i n g and pumping on the s o l i d to remove t r a c e s o f non-condensable prepared.  gas b e f o r e the mixtures were  D r i e d reagent grade carbon t e t r a c h l o r i d e was used as  a m a t r i x , and f o r the work on D 0 i n GGl^ s o l u t i o n . 2  2-lx.  The Spectrometer: The P e r k i n Elmer 112G spectrometer i s a h i g h r e s o l u t i o n ,  s i n g l e beam, double pass instrument.  The main f e a t u r e s a r e :  a 6o° Potassium bromide f o r e - p r i s m , which a c t s as a f i l t e r to e l i m i n a t e the energy o f unwanted o r d e r s , and a 75 l i n e s p e r m i l l i m e t e r e c h e l e t t e g r a t i n g , b l a z e d f o r maximum i n t e n s i t y a t 12 p  ( 8 5 0 c m ' ) i n the f i r s t o r d e r . -  'Two d e t e c t o r s a r e a v a i l a b l e :  a thermocouple, and a l e a d s u l p h i d e c e l l which has a s e n s i t i v i t y more than twenty times as g r e a t as that o f the thermocouple but  can o n l y be used above 3500 cm-'.  The instrument was  9. calibrated using  the  rotation  of  spectra  Since about and  5 metres,  therefore,  range is  the  of  6jA o r  desirable  achieved  to  for  known l i n e s  H 2 O , H C l , CO2 ,  etc.  optical path  length  water  atmosphere  i n the  when  the  3/^ ,  as  reduce  by p a s s i n g  instrument  accurately  about  a  spectrum i n the the  to  case  of  of  of  112G  shows  the  instrument  is  water  the  in  and t h i s  spectrum  the it  is  through is  is  absorption  work w i t h H2O,  d r y n i t r o g e n gas  an hour b e f o r e  vibration-  strong  observed  atmospheric  current  the  (20).  the  be  of  the  recorded.  10.  CHAPTER 3 . 3-1  RESULTS  D?0 In V a r i o u s M a t r i c e s a t k°K. Mixtures of D 0 i n n i t r o g e n , argon and k r y p t o n were 2  prepared and d e p o s i t e d a t %°K.  The r e c o r d e d s p e c t r a of  D2O i n these m a t r i c e s are shown i n f i g u r e s 5 - 7 * observed f r e q u e n c i e s a r e l i s t e d i n Table IV. m a t e r i a l s used as m a t r i c e s a t l i q u i d h e l i u m were oxygen and carbon t e t r a c h l o r i d e .  and the  Other temperature  Unfortunately,  severe s c a t t e r i n g of the i n c i d e n t r a d i a t i o n by the d e p o s i t p r o h i b i t e d the r e c o r d i n g o f s p e c t r a of D 0 i n these 2  matrices:. 3-2  D i l u t i o n S t u d i e s on D 0 i n Argon. 2  The r e s u l t s l i s t e d i n Table IV were o b t a i n e d u s i n g m a t r i x to water r a t i o s  (M/R) o f 200 f o r argon and krypton  and 2 k 0 f o r n i t r o g e n .  As an a i d i n a s s i g n i n g the observed  f r e q u e n c i e s to monomer and p o l y m e r i c s p e c i e s , d i l u t i o n s t u d i e s were c a r r i e d out. 500 were used,  an  r a t i o s o f 5 0 , 1 0 0 , 3 0 0 and  and v a r i a t i o n s o f r e l a t i v e i n t e n s i t i e s of  peaks were noted. i n Table V.  M/R  The r e s u l t s of these s t u d i e s are g i v e n  <a f i g u r e s 2 -  k.  To ensure u n i f o r m i t y o f c o n d i t i o n s , each mixture  was  prepared w i t h the same t o t a l p r e s s u r e , and the mixtures were d e p o s i t e d a t 200 microns  a  constant needle v a l v e opening,  on the low p r e s s u r e s i d e o f the v a l v e .  giving For  11.  TABLE IV.  Spectra o f D 0 i n v a r i o u s m a t r i c e s a t %°K, f r e q u e n c i e s i n cm-' 4  Argon B 210  Krypton  Nitrogen  M/R  M/R « 2ip3  = 210  2ii.35  2578 2589 2594 2609) 261L) 2615) 2622 2635) 2637)  m w vw  2576 s 2586 s 2591 m  2598 m-s 2599 s  vs  2610) _ 26ll|.) 2625 m 2632) _ 2635)  26li). m* 26ll|. w 2639 w» 2650 w 2655 s  2723 2737 27I4.5 2758 2770 2782 2793 28o5  w m vs m m vs s vw  2727  vs  2705 s 2725 m  2740 2751 2765 2775 2787 2800  s vw m s m vw  1154 1159  w vw  II63  w  1172: 1176 1182 1188 1191 1200  w m s  1179 vs  s m  1193 1203  II64  w s m  w  1170 vw 1175 m 1177 s 1186 m II89 s 1195 vs 1203 w 1212 vw LEGEND  v - very,  2738.5 s 2757 s 2765 vs  m  s - strong,  w - weak,  observed during warm-up.  m w-*  m - medium,  12.  Peak I n t e n s i t y Changes i n D i l u t i o n S t u d i e s w i t h D 0 i n Argon a t l\9K. 2  50  100  300  5oo  13 3  7 10 14 2 27 24  5 5  32 8  4 25  10 78  21 26 20 7 7 8 19 3 4 15 6 2 2 1 2 1 9 13  12 11  18 8  12  8  9 17  f 18 4 12 3 20 30  2 9 13 3 1  16 16 48 7 2  25 28 76 18 6  _  3 4 2 _ _  18 15 9 1 _  3 1 2 _  _  3 6 7 6 9  -  —  -  -  -  7 20 8 ,9 48 21 3 11 2 11  -  -  108 S  13 comparable s p e c t r a , the amount o f D 0 i n the d e p o s i t should 2  be constant, hence d i f f e r e n t d e p o s i t i o n times were necessary r a n g i n g from 1 hour f o r the 50 to 1 mixture up to 54hour s f o r the 500 to 1 mixture.  The i n t e n s i t i e s i n Table V  have been c o r r e c t e d so t h a t they r e f e r to a constant amount of D 2 0 . 3-3  Warm-up S t u d i e s . The  d e p o s i t s o f D 0 i n v a r i o u s m a t r i c e s have been 2  observed d u r i n g the warming p e r i o d a f t e r the l i q u i d h e l i u m r e f r i g e r a n t had evaporated,  ^he changes i n peak i n t e n s i -  t i e s and widths a s s i s t i n c e r t a i n cases i n the assignment of f r e q u e n c i e s to monomer and p o l y m e r i c D 0 . 2  A typical  warm-up study i s shown i n P i g . 1 1 , where the m a t r i x was krypton. D 0 2  3-J4-  Other warm-up s t u d i e s have been c a r r i e d out with  i n n i t r o g e n and argon with s i m i l a r r e s u l t s . DpO i n V a r i o u s M a t r i c e s a t 77°K. Three m a t r i c e s have been employed u s i n g l i q u i d  n i t r o g e n as r e f r i g e r a n t ; and ammonia.  carbon t e t r a c h l o r i d e ,  chlorine  Each o f these m a t e r i a l s has a m e l t i n g p o i n t  c o n s i d e r a b l y above 77°K, and should t h e r e f o r e be r i g i d enough f o r use as a m a t r i x a t t h i s temperature.  However,  the observed s p e c t r a i n d i c a t e that D 0 monomer i s not 2  isolated.  T h i s may be a t t r i b u t e d to e i t h e r the l a r g e  size  of the m a t r i x molecule, p e r m i t t i n g d i f f u s i o n o f D 0 molecules, 2  or the f a c t that an absolute low temperature,  r a t h e r than a  r e l a t i v e one i s necessary to m a i n t a i n good i s o l a t i o n o f  illreactive  species.  The in  spectrum  i n carbon t e t r a c h l o r i d e a t 77°K  of DgO  the r e g i o n 2550 - 2750 cm ' -  i s shown i n P i g . 1 2 a .  two broad bands correspond to peaks due s p e c i e s p r e v i o u s l y found a t 3-5  DgO  to p o l y m e r i c  k°K.  i n L i q u i d Carbon T e t r a c h l o r i d e .  A s a t u r a t e d s o l u t i o n . o f D2O t e t r a c h l o r i d e was approximately  0.1$  prepared. D 0 2  (21),  i n t r o d u c e d i n t o a 10  i n pure dry  carbon  This s o l u t i o n contains and corresponds  "matrix" to water r a t i o of 1 0 0 0 .  The  to a  solution  was  cm c e l l w i t h NaCl windows and  i n the r e g i o n 2 6 0 0 - 2800 cm"'  spectrum  The  was  the  recorded  (Pig.12b). The  s h i f t s of the  y,  and  bands from the  phase f r e q u e n c i e s were 28 and 35 cm"' s m a l l peak at 2695 cm-'  i s the 0D  respectively.  stretching  2  t r a c e of H 0 2  Support  p r e s e n t i n the "dry" carbon  f o r t h i s assignment was  The  frequency  formed by hydro/gen exchange between D 0  of HOD,  gas  and  the  tetrachloride.  found by r e p e a t e d  d i l u t i o n of the s o l u t i o n w i t h "dry" CGI4..  The 2 6 9 5 cm" '  peak i n c r e a s e d i n i n t e n s i t y while the peaks a t 26I4.3 and 2753 cm- ' decreased. 3-6  H?0  i n Various M a t r i c e s a t k°K.  The r e c o r d i n g of a c c u r a t e s p e c t r a of H 0 2  and k r y p t o n m a t r i c e s was  very d i f f i c u l t  i n nitrogen  using a single  i5< beam spectrometer.  The reason i s that atmospheric  water  vapour absorbs very s t r o n g l y i n the same r e g i o n as the trapped H2O.  Thus, the spectrum must be obtained by  s u b t r a c t i o n o f a "blank" o r background water vapour  spectrum.  F i g u r e s 8 - 1 0 show the s p e c t r a o b t a i n e d f o r H£0 i n n i t r o g e n and krypton.  The r e s u l t s o b t a i n e d by O g i l v i e  from H^O i n argon are i n c l u d e d .  It is felt  (15)  that the s p e c t r a  o b t a i n e d may be incomplete, and c e r t a i n weak peaks may have been missed.  The f r e q u e n c i e s found are l i s t e d i n Table V I .  1 \  16.  TABLE VI  Observed F r e q u e n c i e s (cm !) f o r H 2 O i n Argon, Krypton and N i t r o g e n M a t r i c e s @ k°K. -  Argon M/R = 3 0 0 3376 3396 3kl6  Krypton M/R = 3 8 0  w vw vw  3510  m  357k 3633.5 3699 370b 3725 3757.5 3777  vs w s vs m m m  1593 1602 1608 l6l0 l62k 1638 I663  vs m s s vs m w  Nitrogen M/R = 2k0  3kl8 3kk3  w w  3509  w  35kk  w  353k 3686  m vs  3725  vs  m w s  1598  vs  S-:H:-  1630  m  3kk0 3q.66 3508 3526 3560 3570  vw vw w 9« m s  3687 3700 3713 37k6  s vs m vs  1591 1600 1606 1625  -^Observed during warm-up. •---"-Broad band observed i n another run w i t h M/R NOTE:  • 210  The s p e c t r a f o r HpO i n a r g o n were o b t a i n e d Ogilvie  (15)  by  17.  F i g u r e s 2, 3 and k D 0 2  i n Argon a t k°K, d i l u t i o n s t u d i e s .  The f o l l o w i n g s p e c t r a were t r a c e d d i r e c t l y from the r e c o r d e r c h a r t s .  Because of  space l i m i t a t i o n s o n l y p a r t o f the V bands are shown.  2  and  >j  1®.  fig 2,  D0 2  in  ARGON at 4°l< dilution s t u d i e s  2635 c m '  V,  2614 c m - '  region  1195 c m - '  1177 c m "  20.  fig 4  D 0 in A R G O N at dilution studies 2  2781-5 c m - '  4°K y  3  region  2745 c m "  21.  F i g u r e s 5>, 6 and D0 2  7.  i n Argon, Krypton and N i t r o g e n a t ij.°K.  The f o l l o w i n g n i n e s p e c t r a were o b t a i n e d u s i n g m a t r i x to water r a t i o s of 210 f o r Argon, 210 f o r Krypton and 2lp0 f o r N i t r o g e n . I n t e n s i t i e s are expressed as % a b s o r p t i o n i.e.  %  1~ « J  To  22..  60-  •z o  fig  5c  0  2  0 ^ H  t  at  4°K  D  t  region  — to-  tal  CC ro\ t  O  (0 CD W-l  10]  2^0  "i  rrr Z60 0  A 1  r-  2650  1700'  23.  2kfig  7  INFRARED IN  SPECTRA  of  D„0  at  4°K  2>< REGION  ARGON  50O 40\~  o. 30 on  o  in 2 0 cn  <  10-  2750  2 70 0 IN  2800  cm-  KRYPTON  50z: o  4 0-  i—  c_ 3 a a: o  w CO <  20 102 750  27 00 908  Cc)  IN  2800  cm  NITROGEN  a  70 60 o  I-a: o  CD  <  50. 40 30 20 10  27 0 0  2 750  2 8 0 0 cm-1  25.  F i g u r e s 8 , 9 and 1 0 . H2O i n Argon, Krypton and N i t r o g e n a t  J4.0K.  The f o l l o w i n g s p e c t r a were o b t a i n e d u s i n g M/R  ratios of:  300 f o r argon, 380 f o r  krypton and 2k0 f o r n i t r o g e n .  The r e s u l t s  f o r argon were o b t a i n e d by O g i l v i e are i n c l u d e d here f o r comparison.  ( 1 5 ) and  "i  • •.i •  i : •' i  8  fig  1  %  :  :. . j . ! .;..;.!. ; ~T'. Tj " T:. •: I :.. :'. i;::: |....  ;  1  r- 1  T  r  "•1  :  F R A FSEDLLS P £ C T R A  1  !::: •  IN  ::! ::. . | .  ,01  i;  i  . : 1 . . . . • i  . : .ii : ! : . .  ::' I::: : •; ":"I""™ i• j •ir ;:!; ! i j!1., ... . i j• ;: j. .  ..::  •» on. r  r  :;.:  M<60  :  if:.:  r  • :|.:.  O j - : yrj;|.--  j  ;  i  --  -:-  L._.......  :  -:;  -r-  ... , . .. .  1  !  J  T:T:  1 - -:  :: |  -iirrri  *•'i  KRiYP T O N IN i ' 1 ... I . .  :::•!:: -j  : j:..:; : ' : ' ! : : : :  . . M -1 •' •: :::: |: •:: ' .... | ' | ;i •:! •' ::.:  • '' ! I  !:: ... '. ' ' '  '  j  t 00 •' :!3'  : :  ~7:|  ~T::r i~  l  TT-T~-  i••  • • • i" i I• l  ::.::: I i  ;; ;  CC)  IN NITR OGE '.... V ' • , ,1 1 jl . . . „ ^ :'; j :: ; . i •;: • ",.':\: . , :'. i, ' . • . j.::: .:::]'::, :::, •i '; •: i ' . ' . »40  >><:  .  r*:| :: _|.: : •::| ::. _20  b i.;....  T-.: ;  ::' I.: ,  : *l Q -  r  \  :  y  400 . ::  •'-'••!-:: :  •!:••  •: • j..:.  i  i .  '•\"t-  .:.:.!  - - • • .... \ :  :: *:- ~r. .:::):::  ~r  •:.:!: :: ';•;!.::  -  - r r r h t r ^:~r rr: r  -. . . i . i .  : :.:. i. .;  :::: j :  00  —  c nh  /  :  •i ! i''. ' :.:.[.::.:.:.  j. . ,.  :  \". I i  I:-.:  !' i  .  1|. . ..:  .. . 1  :  •-' ..: •: .....  : ±  |  :;!  • ! •' f - .. . .:: -j :  li:..-  J—i-—L-L  • ! •  /  .i' :'  : j.  . :|.3 50 0 :  :  ;  ':: :  :  : •  :: " |.::: .........  :  ' ' ' h-  : \  • •; i ; '  •:  •  ......  :'.'.•[ -.:.M " •:. i •  ... j.','  :  hiii::;:  •,.  -  :  .......  3!C>0 1  :.; 11.  :  :I-:T;-I~ i -:::•!•: •• |: ::!::.•:  I '• i  k; . ; J ; ,.  ii •  :  l.-.i:  • 11  I..::  :: i::..  :.:!;..  .......  ,...}—.. . :. : :. |J. .. : :.  :•!:•;; ..... ;..: j . !.. !-!•:; :. !: Jl__.lL- J;r-t-r-  I ••  • •!  '' •' |: :  1  /j  ii.'h:  :!•:•:  :...! :•' :.:'!•::.  . !••[|  ~:-|  •:l . j : . . .:.:.. L ....... : •! .,.....  i  ..j .  ::  •  1 :  :  i:::r.:: :. !:,•" . . , .; ;. •.  .I,, 1 •-•i•  :  .•i  ;:j,:::  i • • -1  • ':• i : :;;i'Jl!  •.:.::!•.:. •  3! ( )0  • 1  -  , . .Tj. , , .  ::.•!:::;  1  .. 1 . : .  '...!..  ::ifi:!|  • j;:_:;: :::•!:;:: ;'.:!::'  j  1  ';: i :.. | •: , ,::: r:; 1  m-  c  ... j . . . . . ..|. , :..: j":: :: ;|; ' ::: l ; i •'. j •'• • • — IT. ... 1 .  ;~|;-:::  1  L  • • • i• • • -  I  r  '::. i  T T VT-T-'-  • OQ  :  •:]•::•  i.  ::: I •.: • •  ;::; i — i  :  J  ::: ;i  :::: j  :::: • •i ••::i •  ; j i-n  •T:r  •r r:  .•- 1  •"I •  -  1  •;t  lb)  •r: r ........  •;  - : • j;.: •  1: :.Lj ii  35JP  . :! "~ ~. \" r  \|i:i -«-j"; -• ..., 1...  p r; r; ~r  T  :  ;;j;  •-— j  i —  :  ;. • j • :  ! • ;.j j":'  •J,.,:  ;!'•:: " • : . : : ! ; ; • :  •  10: IT  1 • • ' ; '  '. 1'.!  : • •: i ; : :  ••!!::•  .I..  . , :. .i 1. .. .  ;  :  -  L:  • i : •• ii [" '  • i" •  . (. .  ioq  ::;. j  :!'!!•:  :  :'.._,:.  . »_o. :; : r; ... ;  ..Li  1  : :  :.::!!;  ij  t  h  • •:: i. '  __]i]_ii  RE  ,  i ... h :  :  . ....... : ; i:,  .;.!.. :  .. .... . ... •:r:v-i; ''i .: •: j : . : : : ' . j • • ; t • '• . ' \ :':i:. ;:|; :: -: r f . . ! .:j.' . ::i :  Si!:;; —-  ;  :: j : ;  t  •..: J ':'  . 1  :j:n:  •  V. : i  I  :  !' :..: i: I '; . .  M  !i .: i : . : :: 1  .-  1  !  at  Qii.jH-0  •i  |... ,. . ' : ! : : '' .!:: .. . : .  • •' • l > ' • :  c m T.': ....... .p.  27.  NER4RE0  28.  29.  F i g u r e 11. A Warm-up Study - D 0 2  i n Krypton.  The temperatures were e s t i m a t e d from thermocouple  r e a d i n g s d u r i n g the warming  p e r i o d a f t e r the l i q u i d h e l i u m r e f r i g e r a n t had evaporated.  30. fig A  II. WARM-UP  y>.  2 600  STUDY  of  REGION  D 0 2  in  KRYPTON  V  2650  2700  from 4°to 60°K  REGION 2  2 7 5 0 cm-i  31.  Figure 12a CGI4.  shows the spectrum of D 0 2  m a t r i x a t 77°K.  assigned  to  F i g u r e 12b  and y  in a  The two broad bands are of D 0 . 2  3  was o b t a i n e d from a s o l u t i o n of  C C I 4 . s a t u r a t e d with D 0 2  a t 25°C.  s t r o n g bands are due t o X the weaker peak i s assigned s t r e t c h o f HDO.  The two  and >$ o f D 0 , 2  to the OD  32.  33,  CHAPTER k  DISCUSSION  Assignments to Polymeric  Species.  Complex s p e c t r a have been observed f o r the r e g i o n s of the three fundamentals of H 0 2  nitrogen matrices.  and D 0 2  i n argon, krypton  and  A p r e l i m i n a r y step i n the q u a n t i t a t i v e  d i s c u s s i o n of these s p e c t r a i s to a s s i g n c e r t a i n peaks to p o l y m e r i c species, f o r example to dimer, other low polymers and h i g h e r  polymers.  Experimental Evidence f o r Polymers;C e r t a i n i n f r a r e d a b s o r p t i o n peaks have been a s s i g n e d to polymeric s p e c i e s on the f o l l o w i n g experimental (i)  evidence.  Peak width a t h a l f h e i g h t ( Peaks have been observed with widths  from 2 to 50 cm"' matrices.  ranging  i n the s p e c t r a of water i n v a r i o u s  I t i s reasonable  to a s s i g n the v e r y broad bands  to h i g h polymer, s i n c e the bands i n i c e due  to H 0 2  and  D0 2  polymer are s e v e r a l hundred wave numbers i n width a t h a l f height.  The v e r y sharp peaks on the other hand approximate  i n width to the gas phase peaks, and are probably due i s o l a t e d water monomers.  to  For peaks i n t e r m e d i a t e i n width,  assignment i s u s u a l l y made to low polymers.  I t i s not  p o s s i b l e to make u n e q u i v o c a l assignments to dimers on peak width evidence (ii)  alone.  Behaviour  d u r i n g warm-up:-  Changes i n peak i n t e n s i t i e s and widths have  34  been observed  d u r i n g t h e warming p e r i o d  h e l i u m r e f r i g e r a n t has regularly first  as  evaporated.  the temperature  t h e n d e c r e a s e , and  the  liquid  C e r t a i n peaks  rises,  a third  after  decrease  others increase at  type  i n c r e a s e and  broaden  as warm-up p r o g r e s s e s . Pimentel temperatures  (l6)  found  c o n s i d e r a b l y below i t s m e l t i n g p o i n t .  would a l l o w d i f f u s i o n lattice.  I f two  dimerization w i l l intensity  that a s o l i d matrix softens at  of water molecules  water m o l e c u l e s occur.  peaks  that  o f t h e warm-up and  as t h e warm-up p r o g r e s s e s c a n u s u a l l y be  to dimer  o r low p o l y m e r .  molecules  become more a c t i v e  r e s t r i c t e d by occur,  and  intensity usually  the m a t r i x ;  and movement becomes  less  water  a t the expense of s h a r p e r peaks  are  An  example o f t h i s b e h a v i o u r i s  where i t i s s e e n as  that  the peak a t  2625cm""'  the d e p o s i t warms f r o m ij. t o 20°K.  s t a g e s o f warm-up when t h e m a t r i x i s b e g i n n i n g away f r o m  in  spectrum. (iii)  the window, o n l y b r o a d p o l y m e r  Intensity Dilution  several  the  and  i n intensity  sublime the  assigned  increase i n width  shown i n F i g u r e 11,  In l a t e r  then  c o n s e q u e n t l y , p o l y m e r i z a t i o n can  a s s i g n e d to polymer.  increases  then  t h e warming p r o c e e d s ,  the b r o a d e r peaks t h a t regularly  crystal  increase i n  decrease  As  the  s h o u l d come t o g e t h e r  Observed  d u r i n g the e a r l y p a r t  through  This  interesting  changes i n d i l u t i o n studies with D 0  effects  2  bands  remain  studies:-  i n argon have  i n the i n f r a r e d  to  spectrum.  shown  35.  Going from M/R = 5 0 to 5 0 0 , c e r t a i n peaks i n c r e a s e i n r e l a t i v e i n t e n s i t y , while  others decrease.  r a t i o i s i n c r e a s e d i t i s reasonable  When the M/R  to expect t h a t the  p r o p o r t i o n o f monomer i s o l a t e d w i l l i n c r e a s e , and sharp peaks which show a continuous  i n c r e a s e are thus a s s i g n e d  to monomer.  On the other hand, broad peaks which decrease i n i n t e n s i t y on d i l u t i o n , must be due t o polymers.  F i g u r e s 2-1). i l l u s -  t r a t e the changes i n the s p e c t r a observed as the argon to D 0 2  r a t i o was changed from 5 0 to 5 0 0 .  An i n t e r e s t i n g  feature  of the s p e c t r a o b t a i n e d from d i l u t i o n s t u d i e s i s that c e r t a i n peaks at f i r s t subsequently  i n c r e a s e i n i n t e n s i t y as M/R i s i n c r e a s e d and  decrease a t the h i g h e r M/R r a t i o s .  To make use  of t h i s behaviour i n the assignment o f such peaks, the s p e c i e s present 50  a t v a r i o u s M/R r a t i o s are c o n s i d e r e d .  the predominant s p e c i e s p r e s e n t  polymers  At an M/R o f  i n the d e p o s i t are h i g h  and monomers, low polymers being l e s s  likely  because o f the p r o b a b i l i t y o f f u r t h e r p o l y m e r i z a t i o n . of 5 0 0 the m a j o r i t y o f the water w i l l be p r e s e n t monomers.  So i t i s reasonable  At M/R  as i s o l a t e d  to expect that a peak t h a t  i n c r e a s e s a t f i r s t and then decreases as M/R i s changed from 50  to 5 0 0 i s due to dimer or low polymer.  i n the V,  The 2 6 3 7  cnr'peak  band o f D 0 I n argon c l e a r l y e x h i b i t s t h i s 2  behaviour (see F i g u r e 2 ) . (iv)  Frequency s h i f t s i n condensed s t a t e s : It  i s w e l l known t h a t when water i s condensed  from the gas phase to the s o l i d s t a t e , there are s h i f t s i n  36.  the observed f r e q u e n c i e s .  The s t r e t c h i n g modes s h i f t to  lower wave numbers, while the bending mode s h i f t s to a l e s s e r degree  to h i g h e r f r e q u e n c i e s .  The magnitude of the  s h i f t depends on the degree of p o l y m e r i z a t i o n . the V  3  band of D 0  For example,  i c e i s s h i f t e d by some 300 cm""'  2  gas phase frequency, while lower polymers produce s h i f t of the order of 50 to 100 recorded f o r D 0 2  cm '.  i n a carbon t e t r a c h l o r i d e m a t r i x a t 77°K,  of the i - b a n d i s -75 peak at 2 6 l 0 cm ' -  ency s h i f t ,  .  cm ' -  The frequency  from the gas phase.  The  shift  second  i s a s s i g n e d to V| with a frequency  -  cm '  a frequency  In the s p e c t r a  -  two f a i r l y broad bands were observed.  of -70  from the  shift  On the b a s i s of the r e l a t i v e l y "small f r e q u -  these bands are assigned to low  polymers.  In the s p e c t r a of i c e (high polymer) the V, and  V,  bands  o v e r l a p and cannot be r e s o l v e d .  Assignments  to polymers  i n s p e c t r a of  HpO:  On 'the b a s i s o f an e x t e n s i v e d i l u t i o n study, Van Becker and Pimentel (12)  Thiel,  a s s i g n e d a l l the observed peaks i n  the spectrum of H 0  i n n i t r o g e n at 20°K to monomer, dimer  and h i g h e r polymers  (see Table 1 ) .  2  H0 2  i n n i t r o g e n at i|°K, u s i n g a M/R  In the p r e s e n t work w i t h r a t i o of 2J4.O, a  v e r y s i m i l a r to that o f Van T h i e l et a l was s i m i l a r assignments  observed,  were made based on peak width,  s h i f t s and behaviour d u r i n g warm-up.  spectrum  For H 0 2  and  frequency  i n argon  and  krypton the s p e c t r a are more complex and more than one peak  37  i s assigned  to monomer i n the r e g i o n of the V% and  fundamentals. and M i l l i g a n  T h i s phenomenon has been observed by  Catalano  (li}.) who r e p o r t e d complex s p e c t r a f o r the  band, and G-lasel (13) who r e p o r t e d s i m i l a r r e s u l t s f o r 24 . Table V I I summarizes the assignments to polymers f o r the s p e c t r a o f H 0 i n argon, krypton 2  and n i t r o g e n .  It is  observed t h a t even a t d i l u t i o n s as h i g h as M/R = 5 0 0 , appreciable concentrations  of low polymers are found.  An  e x p l a n a t i o n f o r t h i s i s t h a t during d e p o s i t i o n , the poor thermal c o n d u c t i v i t y of the window, and s o l i d  matrix  m a t e r i a l , allows each new l a y e r o f d e p o s i t to remain a t a temperature c o n s i d e r a b l y above liPK  for a finite  d i f f u s i o n of water molecules i s p o s s i b l e .  time, thus  The temperature  d i f f e r e n c e between the copper b l o c k and the newly  forming  s u r f a c e o f the "'deposit would be expected to Increase t h i c k n e s s o f the d e p o s i t i n c r e a s e s . a t h i c k d e p o s i t i s necessary, microns p r e s s u r e  F o r the h i g h M/R  ratios  t a k i n g s e v e r a l hours a t 200  to form, so I t i s not s u r p r i s i n g t h a t  a b s o r p t i o n peaks due t o polymeric F u r t h e r evidence  as the  s p e c i e s are found.  f o r poor thermal c o n t a c t between the copper  b l o c k and the d e p o s i t i s the appearance of the d e p o s i t on the caesium i o d i d e window, v a r y i n g from t h i c k a t the edges to very t h i n a t the c e n t r e . o f the window  This i n d i c a t e s t h a t the centre  d u r i n g d e p o s i t i o n , and d u r i n g r e c o r d i n g of  the i n f r a r e d s p e c t r a , i s a t a temperature c o n s i d e r a b l y above t h a t o f the edges, so t h a t the mixture i n i t i a l l y  deposited  at the centre sublimes and recondenses on the c o l d e r p a r t s  38.  TABLE V I I .  Matrix  Assignments  Kr N  Ar  Kr •  N.B.  cm'  Evidence f o r assignment to polymers.  1630 l62k 163S 1625  20 10 10 25  Broad band. Frequency s h i f t and broadness o f peak. Broad band.  3l|l8 31443 3509 3691 3376 3396 3kl6 3510 3699  45  Frequency s h i f t and broadness o f bands.  Frequency cm"'  N Ar  y\  to H?0 Polymers.  m  3508 3526 3560 3687  30 20  -  20 15 20  1x0 10 20  Broadness o f peak. Weak peaks s h i f t e d by lf?0 cm"' from gas phase. Broad peak. Broadness o f peak. Frequency shift. Broadness Appeared during warm-up.' Broadness o f peak. Increased d u r i n g warm-up.  A l l other peaks l i s t e d i n Table VI are a s s i g n e d to monomer.  39.  of the window. The s i t u a t i o n c o u l d be improved by d e p o s i t i n g more s l o w l y thus r e d u c i n g the warming e f f e c t produced by the stream of "hot" gases impinging on the window.  However,  p r e s e n t s u p p l i e s o f l i q u i d h e l i u m are i n s u f f i c i e n t f o r the long d e p o s i t i o n times that would be needed. p o s s i b l e way  to improve  Another  thermal c o n t a c t between the •  d e p o s i t and the r e f r i g e r a n t i s to use a caesium i o d i d e p l a t e mounted on a s i l v e r gauze.  The gauze would cause  l i t t l e r e d u c t i o n of t r a n s m i t t e d i n f r a r e d r a d i a t i o n , ' but would conduct h e a t away from the c e n t r e o f the p l a t e .  Assignments  to polymers i n s p e c t r a of.DpO:  Table V I I I shows the peaks a s s i g n e d to D2O polymers, u s i n g s i m i l a r arguments  to those employed  i n the a s s i g n -  ments f o r H 2 O . The d o u b l e t peaks a t 2635 and 2637 cm"'  i n argon and  2632 and 2635 cm"' i n k r y p t o n would have been a s s i g n e d to monomer on the evidence of sharpness and behaviour during warm-up.  However, d i l u t i o n s t u d i e s i n argon have shown  t h a t both peaks o f the doublet i n c r e a s e to a maximum a t M/R  =  100  and become weak at M/R  a s s i g n e d to dimers. and 261I4. cm"'  = 500,  thus they are  The s h o u l d e r a t 26l5 cm-'  i n krypton i s assigned s i m i l a r l y .  s i m i l a r assignments f o r D 0 2  i n argon To make  i n n i t r o g e n the peak at 26l7 crn"  and the doublet a t 2650 and 2655 cm ' -  were chosen.  4-0.  However, t h e r e  i s no d i l u t i o n  a s s i g n m e n t s , and t h e s h a r p n e s s together with  their  behaviour  ment t o d i m e r  questionable.  evidence  to support  these  o f the peaks i n q u e s t i o n on warm-up makes t h e a s s i g n -  in. Assignments to DpO Polymers.  TABLE V I I I . Matrix  Frequency cm"'  N  Ar Kr Ar Kr Ar Kr Ar Kr Ar Kr Ar Kr N  Ar Kr N Ar  Kr N Ar Kr N Ar Kr  NOTE  Sh  cm" 1  1203 1186 1182 1202 1200 1212 1210  20 10 10 6 5 8 10  2578 2576 2589 2586 2594 2591 2598 26l5 26:14 2617 2635 2637 2632 2635 2650 2655 2723 2737 2727 2725 2805 2800  6 10 8 10 5 8 30 Sh Sh 3  means shoulder  h 5  Evidence Appeared d u r i n g warm-up. Broadness. Frequency  shift.  Frequency  shift.  Broadness Frequency s h i f t s Warm-up evidence D i l u t i o n studies  -  Appeared d u r i n g warm-up. Dilution NONE Dilution  5  k 10 30 20 8 12  studies.  -  si  2  studies.  NONE D i l u t i o n studies. Increased during warm-up. Very broad. Increased d u r i n g warm-up. Broadness.  \\2  k-2  Isotope  Effects.  Three i s o t o p i c s p e c i e s i n a d d i t i o n to D^O  could give  r i s e to i n f r a r e d a b s o r p t i o n i n the r e g i o n s under examination. They are H 0, 2  D o'  8  2  and D o ' .  Mass s p e c t r o s c o p i c a n a l y s i s  7  2  i n d i c a t e s t h a t the c o n c e n t r a t i o n o f D o'*and D 0 2  low and need not be c o n s i d e r e d of D 0 2  further.  17  2  i s very  However, a spectrum  i c e obtained on the P e r k i n Elmer 1^21 double beam  g r a t i n g instrument  r e v e a l e d the presence o f a t r a c e o f H 0 2  impurity. To i n v e s t i g a t e the e f f e c t on the s p e c t r a of D 0, of 2  HDO produced by hydrogen exchange between D 0  and  2  H0 2  i m p u r i t y , two runs were c a r r i e d out i n an argon m a t r i x u s i n g known percentages of HDO. s o l u t i o n o f $0% H 0  in D0  2  HDO and 2%fo o f H 0 2  2  F o r the f i r s t r u n a  was prepared.  and D 0. 2  F o r the second run, a  s o l u t i o n c o n t a i n i n g 38$ HDO, $6% H 0 2  prepared.  T h i s g i v e s %0%  and 6% D 0 2  was  The M/R r a t i o s were l\\$ f o r the f i r s t r u n and  110 f o r the second.  The mixtures were d e p o s i t e d f o r three  hours a t 200 microns p r e s s u r e .  In the f i r s t r u n peaks due  to D 0 monomer were s m a l l while  i n the second r u n D 0  2  monomer peaks were b a r e l y p e r c e p t a b l e .  2  New peaks were  found a t 2693 cm'' (medium) and 2679, 270l|., 2712 cm'  1  weak) a l l a s s i g n a b l e to  t o HDO.  Peaks p r e v i o u s l y  low polymers were unchanged i n frequency,  those a t 26l5 and 2637 cm-'  (very  assigned  f o r example,  , but much s t r o n g e r than peaks  k-3  due  to D 0 z  monomer.  T h i s i s reasonable  s p e c i e s c o n t a i n i n g an 0-D region.  Thus, the M/R  be  low i n the two  polymeric  bond w i l l absorb i n the s t r e t c h i n g  r a t i o w i t h r e s p e c t to polymers  approaches the t o t a l m a t r i x was  s i n c e any  runs,  to water r a t i o , and s i n c e  this  c o n s i d e r a b l e p o l y m e r i z a t i o n would  expected. I t has been shown then that the presence o f a s m a l l  amount of H^O  i m p u r i t y w i l l have l i t t l e  the s p e c t r a o f D2O. of peaks a t  26l5  and  or no e f f e c t  In a d d i t i o n , support  2637  cm""  1  on  f o r the assignment  to dimer has been  obtained.  44-  k-3  M u l t i p l e Trapping Having a s s i g n e d  Sites.  s e v e r a l broad bands and  c e r t a i n other  peaks to polymeric  s p e c i e s , there remain s e v e r a l sharp peaks  which are a s s i g n e d  to monomer.  These are l i s t e d i n Table  IX  where i t i s seen t h a t the frequency d i f f e r e n c e s , between peaks observed i n argon and krypton m a t r i c e s , The water molecule has frequencies than one  and  cannot give r i s e  normal v i b r a t i o n a l a b s o r p t i o n  then more than one  i n the r e g i o n of  symmetry i s  c r y s t a l s t r u c t u r e of the r a r e gases i s cubic (figure 14b).  two m o d i f i c a t i o n s  (23),  ( f i g u r e llpa.).  the oc  No  S o l i d nitrogen exists i n form, s t a b l e below 35°K i s  information  i s a v a i l a b l e f o r the  s t r u c t u r e of carbon t e t r a c h l o r i d e at very low but  temperatures,  i n the temperature range from 225°K to the m e l t i n g  (250°K) i t ' h a s been r e p o r t e d Sub s.ti trot i o n a l and f o r the trapped  species.  replaces a matrix  to be f a c e c e n t r e d cubic  hedral hole.  point (2I4,).  i n t e r s t i t i a l s i t e s are a v a i l a b l e In the former a water molecule  atom or molecule, while  i n the  the molecule i s accommodated i n an o c t a h e d r a l or  «-  considered,  peak i n each r e g i o n i s p o s s i b l e .  c l o s e packed (22)  cubic  to more  However, i f the p o s s i b i l i t y of m u l t i p l e  t r a p p i n g s i t e s of d i f f e r e n t s i z e and  The  small.  three fundamental v i b r a t i o n  (see f i g u r e 1 3 b ) ,  each fundamental.  are  latter, tetra-  S i z e s of the v a r i o u s h o l e s i n the r a r e gases,  n i t r o g e n and  carbon t e t r a c h l o r i d e have been c a l c u l a t e d  and are given i n Table  X.  4*.  TABLE I X .  P e a k s A s s i g n e d t o Monomer i n the S p e c t r a o f D 0 and H 0 . 2  DpO  i[ f r e q u e n c i e s i n cm"' ) Kr  Ar 1154 1159 1164 1170 1175 1177 1189 1195  2  w vw w vw  1156 1163  (Ar - Kr) A V w  3 1  «  s s vs  1172 1176 1188 1191  m m 3  3 1 1 4  2614  vs  2610  s  2745 2758 2770 2783 2793  vs m in vs s  2740 2751 2765 2775 2787  s vw m s m  ffi  1179  vs  1193  m  4  2599  s  5 7 5 8 6  2705 2738 2757 2765  s s s vs  3 p e a k s a t 2 6 l 7 , 2 6 5 0 , 2655 cm"' were a s s i g n e d t o p o l y m e r s w i t h o u t e v i d e n c e , t h e s e p e a k s may be due t o monomer. 2.  H?0  ( f r e q u e n c i e s i n cm"' )  Ar  Ar-Kr  Kr ra  1574 1593 1602 1609  s m vs  1591 1600 1606  m w s  2 2 3  1598  vs  3574  vs  3570  s  4  363i+  s  3708 3724 3757 3777  vs m m m  3700 3713 3746  vs m vs  8 11 11  3725  vs  46.  Diameters Of L a t t i c e  TABLE X.  Matrix  Substitutional  Sites (in  Octahedral  A)  Tetrahedral  Ne  3.07  1.28  0.68  Ar  3.75  1.56  0.86  Kr  4. .02  1.66  0.90  Xe  4.31  1.78  O.96  4.1 CGI4.  5.9  (3.0)  1.7  2.4  (1.2)  O.94 1.4  -::-The maximum diameter f o r n i t r o g e n i s g i v e n f i r s t . F i g u r e s i n b r a c k e t s are c a l c u l a t e d from the minimum diameter o f the molecule.  (O.69)  kl The s t r u c t u r e of the water molecule f i g u r e 13a,  i s shown i n  where the atoms are drawn as spheres w i t h  equal to t h e i r van der Waals r a d i i / v a l u e s o b t a i n e d Pauling  (25>)_7  The  diameter  radii  from  of the water molecule i s  approximately 3.6 A, and by i n s p e c t i o n o f Table X i t i s e v i d e n t that o n l y the s u b s t i t u t i o n a l s i t e s can accommodate a ;water molecule, spheres.  The  without  c o n t a c t of the van der Waals  c o v a l e n t r a d i i of oxygen and hydrogen are  c o n s i d e r a b l y l e s s than the van der "Waals r a d i i the diameter  of the water molecule  b a s i s would be 1.9  (2f?)  c a l c u l a t e d on  A, which i s approximately  and  this  the same s i z e  as an o c t a h e d r a l s i t e . Thus, i t appears  t h a t s u b s t i t u t i o n a l s i t e s might a l l o w  f r e e r o t a t i o n of the water molecule  except n i t r o g e n which,  owing to i t s c y l i n d r i c a l shape might a l l o w r e s t r i c t e d rotation. of t h i s  R o t a t i o n w i l l be d i s c u s s e d i n the next  section  chapter.  In the observed  s p e c t r a there i s one n o t i c e a b l y l a r g e  peak i n the r e g i o n of each fundamental.  These are g i v e n  i n Table XI. I f one p o s t u l a t e s t h a t some water monomers are i n s i t e s which prevent r o t a t i o n e n t i r e l y , Oo-Oo t r a n s i t i o n becomes allowed. distorted octahedral s i t e .  trapped  then the " f o r b i d d e n "  Such a s i t e might be a  The frequency  s h i f t s i n the  v a r i o u s m a t r i c e s are a l s o g i v e n i n Table XI.  It is  n o t i c e a b l e t h a t the s p e c t r a o b t a i n e d u s i n g a n i t r o g e n  TABLE X I .  S t r o n g e s t Monomer P e a k s i n t h e S p e c t r a Of D C1 a n d H 0 ( cm- ) . 1  2  2  y,  Matrix  D0  Argon  2614  -57  3574  -83  Krypton  2610  -61  3570  -87  Nitrogen  2655  -16  3634  -23  Gas  2671  -  3657  -  Argon  1195  17  1609  14  Krypton  1191  13  1606  11  Nitrogen  1179  1  1598  3  phased  2  S h i f t from gas p h a s e  Gas phases- 1178  H0 2  S h i f t from gas phase  1595  Argon  2745  -k-3  3708  -48  Krypton  274O  -48  3700  -56  Nitrogen  2765  -23  3725  -31  Gas  2788  phase  3756  :-The f r e q u e n c i e s q u o t e d f o r t h e g a s p h a s e a r e t h e " f o r b i d d e n " Oo-Oo t r a n s i t i o n s .  49.  matrix  are quite  gas m a t r i c e s . evidence by  different  i t i s only possible  correlating  with  to account  the o b v i o u s  to matrix  b u t w i t h the p r e s e n t  f o r such  dissimilarity  and the s p h e r i c a l  i s a l s o worth n o t i n g t h a t  gas p h a s e  those r e c o r d e d f o r the r a r e  T h i s s h o u l d be s i g n i f i c a n t  d r i c a l n i t r o g e n molecule It  from  o f the c y l i n -  rare  the f r e q u e n c y  differences  gas atoms.  shifts  i s o f t h e same o r d e r as t h a t  from the f o r low  polymers. The  o t h e r monomer p e a k s may be p r o d u c e d  rotating  i n substitutional  sites.  the n e x t  section.  p o s s i b i l i t y i s that  molecules  Another  are trapped i n several  This w i l l  water m o l e c u l e , crystal is  effect  these  sites,  on t h e s p e c t r u m  time.  such  as s i t e s  by d e f e c t s i n the  However, s i n c e  i tis difficult  at this  the water  a r e r e p l a c e d by a  or surface s i t e s produced  l a t t i c e o f the s o l i d m a t r i x .  known a b o u t  be d i s c u s s e d i n  other s i t e s ,  i n w h i c h two m a t r i x atoms o r m o l e c u l e s  by m o l e c u l e s  nothing  to d i s c u s s the  50.  fig 13 a  The w a t e r m o l e c u l e , the atoms a r e shown as s p h e r e s w i t h r a d i i e q u a l t o t h e i r van d e r Waals r a d i i .  fig 13 b  The  normal  vibrations  o f the water  molecule*  51-  fig  A p r o j e c t i o n down a cubic a x i s of the low temperature form of s o l i d n i t r o g e n .  K a  A p a c k i n g drawing of the c l o s e packed cubic s t r u c t u r e of s o l i d N viewed along a cube a x i s . 2  fig U_b.  The cubic c l o s e packed s t r u c t u r e of s o l i d i l l u s t r a t i n e an o c t a h e d r a l s i t e .  i n e r t gases,  52  4-4  R o t a t i o n o f Monomer. The  three The  water molecule  top  d i f f e r e n t p r i n c i p a l moments o f i n e r t i a  a l l o w e d gas  from  i s an a s y m m e t r i c  the  levels  two  and  phase r o t a t i o n a l  lowest  levels,  selection rules  are  (25)  H0  t h a t a t ij.°K o n l y  f o r para molecules  Intensities (25)  and  of r o t a t i o n a l  are  normal h i g h maintained  temperature  level,  w o u l d be be  seen  matrix  areas (i)  However,  a simple  The  compared w i t h V,  equilibrium ratio  3  region; of H 0 ) 2  the e x p e r i m e n t a l  from  funda-  should i n the  s p e c t r a do  on r o t a t i o n .  not The  main  are: peaks. are  t o o few  the p r e d i c t e d s p e c t r u m . 2  is  equilibrium  o f the monomer o c c u r s  instances there  region of both H 0  the  4°K.  f o r the y  number o f o b s e r v e d  In c e r t a i n  I t i s assumed t h a t  i n t e r p r e t a t i o n based  of disagreement  calculated  t h a t i n the r e g i o n o f e a c h  i f free rotation  a t i|_°K.  support  (four  Oo  molecules.  namely t h a t o r i g i n a t i n g  allowed at  then  XII.  level  f o r ortho  I f true thermal  transition,  mental three peaks observed  ortho para  ).  cal-  i s the  t r a n s i t i o n s have been  i n the m a t r i x .  I t may  be  level  i n c l u d e d i n Table XII.  o b t a i n s , o n l y one t h e Oo  t h e 1_,  and  c  energy  the  the l o w e s t That  I  originate  are given i n Table  2  w i t h r e s p e c t to each s p e c i e s i s occupied. level  that  o b t a i n e d u s i n g the  and  2  b e e n shown  ( I / , ^ 1$ ^  f r o m A p p e n d i x I I , and  culated frequencies for D 0 I t has  transitions  s i n c e i t has  and  D0 2  i n argon  For and  peaks  observed  example, krypton,  i n the only  53  D 0 a n d H-O a t [|°K A l l o w e d T r a n s i t i o n s and C a l c u l a t e d I n t e n s i t i e s .  TABLE X I I .  p  Type A Band i R(0)  T 1_,  R(D  2_  R(D  2  P(D  0  H 0  D 0  ^3  2  2  cm"  Intensity  1  cm '  Intensity  J/  r  2  20  3779  10  2811  20  3801  60  28I4.8  l-i  Z  2800  .  o  y, Type B Bands r  10  2776  n  i  J  0.03  J  D  20  r  cm  „,  lo  0  Q(D  1,  l_i  R(D  2.,  1 ,  o  k  3732  30  cm"  Intensity  1200  20  2701  . 1209  15  2682  1190  15  2692 .  R(0)  3863  H 0 2  I  II  cm"'  R(o)  i  Q(l)  1.  R(D  2^,  c  o,,  cm"'  Intensity  3657  1595  10  1-.  3675  1617  h$  1_,  3711  1653  kS  one  peak i s a s s i g n e d  H£0 i n n i t r o g e n of  the y  t o monomer.  there  i s only  fundamental.  x  Similarly,  one monomer p e a k i n t h e r e g i o n  On t h e o t h e r  hand, many more p e a k s  than p r e d i c t e d a r e observed i n the V  z  the V  i n argon, y  the (ii)  z  region  3  region  In the y  2  Shifts.  This  peaks a r e a s s i g n e d assigned sites  section).  i n nitrogen  t o monomer.  (see f i g u r e 7c)  -  remaining  and t h e g a s - m a t r i x  k6 cm"' r e s p e c t i v e l y . means t h a t is  It is due  peaks a t 2738,  to polymerization,  the  that  i s to higher  2800 a n d  are not constant,  Furthermore,  which  spectrum the magni-  a p e r t u r b a t i o n o f the water  i n a l l cases  rotation  entirely.  the gas-matrix  T h i s may be compared w i t h  shift  the s h i f t s  where f o r t h e s t r e t c h i n g r e g i o n s t h e  i s t o l o w e r wave numbers, w h i l e  shift  a t 277&,  s h i f t a r e s e e n t o be 3 8 , l±3 a n d  t h a t m i g h t be e x p e c t e d . t o p r e v e n t i s noteworthy  2757 a n d 2 7 6 5 cnr'  o f peaks i n the observed  represents  t o l o w e r wave numbers.  shift  sharp  o f monomer t r a p p e d i n  n o t t h e same as i n t h e g a s p h a s e .  molecule  four -  These s h i f t s  the s e p a r a t i o n  tude o f the s h i f t s  shifts  r o t a t i o n , (by t h e arguments o f t h e p r e v i o u s  The t h r e e  cm ',  from  The p e a k a t 2 7 0 5 cm ' i s f u r t h e r  may be compared w i t h p r e d i c t e d f r e q u e n c i e s 2811  obtained  i s i l l u s t r a t e d b y t h e f o l l o w i n g example.  t o t h e Oo - Oo t r a n s i t i o n  that prevent  those  s t u d i e s , many anomalous f r e q u e n c y  b a n d o f D2O  3  and f o r  2  isolation  observed.  2  r e g i o n o f D 0 i n a r g o n and k r y p t o n  I n comparing gas phase s p e c t r a w i t h  are  and D 0  o f H2O  of D 0 i n krypton,  Frequency  the m a t r i x  f o r b o t h D2O a n d  frequencies.  f o r the bending  region  55.  (iii)  Intensities. A b e t t e r f i t of observed  f r e q u e n c i e s with the p r e -  d i c t e d can be found i n c e r t a i n cases. V  3  r e g i o n of D 0  i n argon,  2  at 27i)-5 cm"  1  For example, i n the  a f t e r a s s i g n i n g the strong peaks  to n o n - r o t a t i n g monomer, there remain three  strong peaks at 2758, 2783 and 2793 cm"'.  Subtracting  these from the p r e d i c t e d f r e q u e n c i e s , s h i f t s of l 8 , 17 18  cm"  are o b t a i n e d .  1  and  The agreement i s seen to be very good  and the s h i f t i n t h i s case i s not e x c e s s i v e ; however, the i n t e n s i t i e s of the observed peaks do not correspond w i t h the calculated values. i n the r a t i o  The  calculated relative  1 : 2 : 2 ,  w h i l e the observed  2 : 7 : 3 .  i s approximately f o r >> 3  of  An analagous  i n krypton, and  V  x  of DgO  intensities intensity  are  ratio  s i t u a t i o n i s found i n argon and  krypton.  To o b t a i n a go od f i t w i t h the p r e d i c t e d spectrum  in  the above cases, three peaks o n l y were a s s i g n e d to r o t a t i n g monomer.  There s t i l l remain s e v e r a l unassigned  i n t h e observed ;  spectrum.  To account  frequencies  f o r these i t c o u l d be  p o s t u l a t e d t h a t v i o l a t i o n s of the s e l e c t i o n r u l e s occur i n the m a t r i x .  F o r example, the weak peaks at 2770 and 2805  i n the spectrum and 2  0  - 1_  (  of D 0  i n argon,  c o u l d be the f o r b i d d e n 1  respectively.  -  1_,  However, no peaks c o r r e s -  to the other f o r b i d d e n t r a n s i t i o n s were  observed,  and there i s no j u s t i f i c a t i o n f o r making these two in particular  0  t r a n s i t i o n s , c a l c u l a t e d f o r the gas phase at  2796 and 2825 cm"' ponding  2  cm"'  allowed.  transitions  56.  k-5  I n t e r a c t i o n s with the M a t r i x . The l a r g e frequency s h i f t s which i n c r e a s e with the  p o l a r i z a b i l i t y of the m a t r i x , are experimental o b s e r v a t i o n s t h a t i n d i c a t e a s t r o n g i n t e r a c t i o n between the m a t r i x and the trapped water m o l e c u l e s .  F o r example,  i n the V r e g i o n of DgO 3  i n argon, krypton and n i t r o g e n , the frequency s h i f t s are 2 0 , 25 and kO cm '• r e s p e c t i v e l y . -  V a r i o u s m a t r i x i n t e r a c t i o n models may be p o s t u l a t e d , the s i m p l e s t of which i n v o l v e s a d i p o l e induced d i p o l e  inter-  a c t i o n between a m a t r i x atom and the oxygen atom of the water molecule.  This would produce an XYZ^ molecule which would  have s i x normal v i b r a t i o n a l modes ( f i g u r e  f i g 15.  Normal v i b r a t i o n s of an XZZ  O  Z  l5)«  molecule.  57.  Comparing w i t h f i g u r e 1 3 b , V,  correspond c l o s e l y with while y 0-M  and  v  V  6  i t i s seen t h a t  are new  >*  2  and  y  V,  ?  >V  and  >* of the water molecule, 3  f r e q u e n c i e s a s s o c i a t e d with the  "bond" (M being a m a t r i x atom). Using the equations g i v e n by Herzberg  (27),  frequencies  of the normal modes were c a l c u l a t e d f o r the ArOH , and ArOD2 2  molecules. were 7 . 8 H-O-H 0.78  The f o r c e constants used i n these  md/A  f o r the 0-H  s t r e t c h , and 0.6°, md/A  bend (from Wilson Decius and O . 0 6 9 md/A  calculations  and Cross  f o r the  (28).)  were assumed f o r , t h e O-Ar  f o r c e constants i n a p r e l i m i n a r y c a l c u l a t i o n  Values  of  and H-O-Ar ( i . e . 1 0 $ of  the corresponding f o r c e constants of the water m o l e c u l e ) . In subsequent c a l c u l a t i o n s , the f o r c e constants were v a r i e d as i n d i c a t e d i n Table X I I I where the c a l c u l a t e d f r e q u e n c i e s are g i v e n . I t i s evident t h a t t h i s simple model does not g i v e f r e q u e n c i e s t h a t can be used spectra.  to account f o r the  observed  However, i t does show t h a t the three fundamentals  corresponding to >>,  V  t  and V,  of water, are only  d i f f e r e n t from the p a r e n t molecule. model c o u l d be used,  slightly  A more complicated  f o r example a t e t r a h e d r a l 0 H A r  cule which would have e i g h t i n f r a r e d a c t i v e  2  z  mole-  fundamentals.  58. TABLE X I I I .  C a l c u l a t e d Frequencies f o r A r 0 H and ArOD^.  Force Constants Used Md/A  Mode  z  Frequencies i n cm ArOH ArOD_. 2  0-H  7.8  (100$)  3719  2687  H-O-H  O.69  (100$)  331  316  O-Ar  0.78  (10$)  1595  1178  H-O-Ar  O.069  (10$)  38k5  2867  356  260  3523  2541  330 1608  311 1195  3570 364-  2615 270  3619 229  261k 217  1608  1195  v, v  0-H  7.02  (90$)  H-O-H  O.69  (100$)  O-Ar  0.78  (10$)  H-O-Ar  O.069  (10$)  0-H  7 M  (95$)  H-O-H  O.69  (100$)  O-Ar  0.39  (5$ )  3668  2686  H-O-Ar  O.034.  (5$)  257  191  ;  t  V,  -1  59-  4-6  Conclusions. Many p e a k s h a v e b e e n s a t i s f a c t o r i l y  meric  s p e c i e s , and  assignment  of o t h e r f r e q u e n c i e s has  discussed.  A combination  allowed  forbidden rotational  for  and  assigned to p o l y -  of m u l t i p l e trapping s i t e s transitions,  can  t h e p e a k s a s s i g n e d t o monomer i n c e r t a i n  example, this  r e g i o n of D 0  i n the  treatment  i n argon  2  i s inconsistant  2  with  account  cases, f o r  and  krypton.  i n t h a t i t does n o t  the r e g i o n s o f a l l f u n d a m e n t a l s o f H 0  been  and D 0  apply  i n the  2  However, to  various  matrices. A second matrix  e x p l a n a t i o n has  i n t e r a c t i o n model.  not g i v e u s e f u l r e s u l t s i n v o l v e an The ations  and M i l l i g a n of H 0  and  2  4-7  D0 2  and  trapped  Suggestions  simpler matrix  does  forward  by  account  that simple  Glasel  f o r the  i n inert matrices  (13)  and  explanCatalano  complex s p e c t r a a t low  temperatures.  f o r F u r t h e r Work.  involving  a molecule  a molecule  treatment  a  calculation.  shown t h e n ,  diatomic molecules  i n inert matrices.  shown by  involving  more c o m p l i c a t e d m o d e l s w o u l d  t o the c o n d i t i o n s t h a t p r e v a i l  trapped be  those put  (llj.) c a n n o t  A study key  and  p r e s e n t work has as  forward  However, a s i m p l e  e x c e s s i v e amount o f  such  been put  when s m a l l m o l e c u l e s  w i t h a s m a l l d i p o l e moment, e . g .  i n t e r a c t i o n models than c o u l d be  treated.  HCl.  those  would CO  In e i t h e r necessary  a are  Possibly contrasting effects  w i t h a l a r g e moment, e.g.  triatomic molecules  might p r o v i d e  ,  case  for  6o. APPENDIX I P r o p e r t i e s and C h a r a c t e r i s t i c s o f M a t r i c e s , Some p h y s i c a l p r o p e r t i e s o f the m a t e r i a l s used as m a t r i c e s i n t h i s work are g i v e n i n Table XIV.  Becker  and Pimentel ( l 6 ) have d i s c u s s e d the d e s i r a b l e c h a r a c t e r i s t i c s of a matrix.  The m a t r i x must be i n e r t with r e s p e c t  to the s p e c i e s under examination, s u f f i c i e n t l y r i g i d to prevent d i f f u s i o n o f the trapped molecules, and t r a n s parent i n the s p e c t r a l r e g i o n o f i n t e r e s t .  Becker and  Pimentel noted t h a t s m a l l molecules d i f f u s e r a p i d l y and cannot be trapped f o r p e r i o d o f many minutes temperature  i f the  o f the m a t r i x i s allowed to r i s e to the range  O.Jj, - 0 . 6 o f the m e l t i n g p o i n t o f the m a t r i x .  In the  p r e s e n t work i t has been observed that an absolute low temperature  i s necessary.  These authors a l s o  observed  t h a t the vapour p r e s s u r e o f the m a t r i x must be below 10" mm Hg a t the temperature  o f the r e f r i g e r a n t , g i v i n g a  r e s t r i c t i o n on the upper l i m i t to the temperature  range  i n which a m a t r i x can be used, e.g. f o r xenon about ?0°K, f o r argon about 35°K and f o r n i t r o g e n about 30OK. A p r o p e r t y which may l i m i t or even p r e c l u d e the use of a m a t e r i a l as a m a t r i x i s l i g h t s c a t t e r i n g .  For this  reason a g l a s s y r a t h e r than a c r y s t a l l i n e m a t r i x i s d e s i r a b l e . Catalano and M i l l i g a n  (ll].) noted t h a t they were unable to  r e c o r d the spectrum o f H^O i n xenon i n the s t r e t c h i n g r e g i o n because  of excessive scattering.  In the p r e s e n t work  6i.  TABLE XIV  P h y s i c a l P r o p e r t i e s of M a t r i x M a t e r i a l s . Ne  Property Melting  Point  Boiling  Point  oc °K °C °K  Crystal  Structure  Ar  Kr  Xe  - 2 4 8 . 7 - 1 8 9 . 2 - 1 5 6 . 6 -112 24.4  83.9  116.6  N  CCl^  2  -209.9  l6l  - 2 4 5 . 9 - 1 8 5 . 7 - 1 5 2 . 9 -107  -22.8  63.3  250.5 76.8  -195.8  27.3  87.5  120.3  166.2  CCP  CCP  CCP  CCP  77.4  350.1  Cubic-::-  FCC  (A)  4.52  5.43  5.71  6.25  5.64  8.34  Molecular diameter i n c r y s t a l (A)  3.07  3.75  4.02  4.31  4.1 3.0  5.9  C e l l Edge  a  0  Heat of F u s i o n cal/mole Heat of Vapourization cal/mole  *  80  268  34O  550  170  640  410  1600  2240  3100  1333  7146  i s cubic below 35°K.  Solid  The N molecule i s c y l i n d r i c a l ; the approximate dimensions are 4 . 1 A l e n g t h and 3 . 0 A diameter. z  Estimated  from the value o f  a,.  62 a t k°K i t was was  observed  t h a t i n t e n s i t y l o s s due  n e g l i g i b l e w i t h n i t r o g e n , n o t i c e a b l e with  to  argon,  c o n s i d e r a b l e w i t h krypton and v e r y s e r i o u s w i t h tetrachloride, increasing with theory  i n d i c a t i n g that s c a t t e r i n g  carbon  increases with  s i z e of m a t r i x atoms or molecules, (29).  scattering  i n agreement  63 APPENDIX I I . Symmetry P r o p e r t i e s , S e l e c t i o n Rules and Energy L e v e l s f o r H2O and D2O. Symmetry P r o p e r t i e s  of Rotational  Levels.  Each energy l e v e l o f an asymmetric top has one o f the symmetries  -f--/-  -f-—  .  —-f  behaviour with r e s p e c t  The f i r s t  s i g n r e f e r s to  to a r o t a t i o n by l 8 o ° about the a x i s  of l a r g e s t moment o f i n e r t i a .  The second s i g n r e f e r s to a  s i m i l a r r o t a t i o n about the a x i s o f s m a l l e s t moment o f \ inertia. (i)  The signs a r e o b t a i n e d as f o l l o w s : F o r the f i r s t for  s i g n , the h i g h e s t  value of T  any J i s -f~ , the next two lower are — ,  the next two -f- e t c . (ii)  F o r the second s i g n , the lowest y f o r any J i s -f~ , the next two h i g h e r a r e — ,  the next  two -f- e t c . Hence, the symmetries o f the r o t a t i o n a l l e v e l s for  J = 0, 1 and 2, a r e : Oo  •+  +  1- i  "  lo  -  -  +  +  1,  2- 2  2-,  2 o 2 ,  -  +  -  -  -  +  6k. Selection  Rules.  The s e l e c t i o n r u l e s f o r J a r e : J = 0, ± 1 The symmetry (i)  J  s  0  J = 0  selection rules are:  F o r A type bands ( i . e . the d i p o l e moment change d u r i n g v i b r a t i o n i s along the a x i s o f l e a s t moment o f i n e r t i a ) y, i s o f t h i s type. and  ( i i ) F o r B type bands ( i . e . the d i p o l e moment change d u r i n g v i b r a t i o n i s along the a x i s o f i n t e r mediate moment o f i n e r t i a ) this  type.  (-/--+-*-?> Energy  V, and ^ are o f  )  and  (-/--<->—+)  Levels. The r o t a t i o n a l energy l e v e l s are g i v e n i n Table XV.  To o b t a i n itions,  the f r e q u e n c i e s o f v i b r a t i o n - r o t a t i o n  the lower s t a t e energy l e v e l J  from the upper s t a t e energy l e v e l J  T  •  trans-  n i s subtracted  65.  Energy L e v e l s o f H2O and D2O.  TABLE XV.  1. D 0 (cm"' ) 2  100  010  001  0.0  2671.7  1178.5  2788.1  l-i  12.1  2683.7  1190.6  2800.1  lo  20.2  2691.7  1199.9  2807.6  ll  22.6  2694.O  1202.5  2810.1  35.8  2707.0  1214.4  2823.6  2-/  q.2.0  2713.1  1221.5  2829.3  2o  49.3  2720.3  1229.2  2836.7  2 ,  73.6  2744.3  1256.9  2859-4  2  74.1  2744.8  1257.4  2859-9  000  Jr  0  t  4  3  4  0.0  3657.1  1594.8  3755.8  1-/  23.8  3680.4  1618.6  3779.4  lo  37.1  3693.3  1635.1  3791.5  1,  42.4  3698.4  1640.6  3796.8  2-2  70.1  3725.9  1665.0  3824.9  79.5 95.2 134.9 136.2  3734.9 3750.6 3788.6  3833.4 3849.1 3885.6  3789.8  1677.1 1693.7 1742.4 1743.6  2  1  2  1  reference  2.  4  H 0 (cm-' ) 2  0  2-i  2o 2 , 2i referenc e  3887.1  66. BIBLIOGRAPHY. 1.  B e n e d i c t and P l y l e r , N.B.S. J . o f Research, k 6 , 2 k 6 ( 1 9 5 1 )  2.  Dalby and N i e l s e n , J . Chem. Phys. 2 £ , 9 3 k ( 1 9 5 6 )  3.  Dickey and Hoffmann,  k.  Benedict, G a i l a r and P l y l e r , J . Chem. Phys. 2 k , 1139 ( 1 9 5 6 )  5.  Ellis  6.  Gartwright, Phys. Rev. k ^ k 7 0 ( 1 9 3 6 )  7.  C o l l i n s , Phys. Rev. £ 5 , k 7 0 (1939)  8.  Pox and M a r t i n , Proc. Roy. Soc. (A) 17k, 2 3 k ( 1 9 k 0 )  9.  Giguere and Harvey, Can. J . Chem.  J . Chem. Phys. _23, 1 7 1 8  and Sorge, J . Chem. Phys; 2 , 5 5 9  (1955)  (193k)  798 ( 1 9 5 6 )  10.  Ockman, Advances i n P h y s i c s , 7, 1 9 9  (1958)  11.  Haas and Horning, J . Chem. Phys. £2, 1 7 6 3 ( i 9 6 0 )  12.  Van T h i e l , Becker and Pimentel, J . Chem. Phys. 27_, . k 8 6  13.  Glassel,  lk.  Catalano and M i l l i g a n , 3 0 , k 5 ( 1 9 5 9 )  15.  O g i l v i e , M.Sc. T h e s i s , U.B.C. (1961)  16.  Becker and P i m e n t e l , J . Chem. Phys. 2j>, 2 2 k ( 1 9 5 6 )  17.  W h i t t l e , Dows and Pimentel, J . Chem. Phys. 2 2 , 1 9 k 3 ( 1 9 5 k )  18.  Bass and B r o i d a , Formation and Trapping o f Free R a d i c a l s , Academic P r e s s , New York ( i 9 6 0 )  19.  D e u r i g and Mador, Rev. S c i . I n s t r . 2 J , k 2 1 ( 1 9 5 2 )  20.  Tables o f Wave Numbers f o r the C a l i b r a t i o n o f I n f r a r e d . Spectrometers, B u t t e r w o r t h s , London ( 1 9 6 ! )  21.  Seidell,  22.  Wyckoff, C r y s t a l S t r u c t u r e s , I n t e r s c i e n c e P u b l i s h e r s , New York ( 1 9 k 8 - )  23.  B o l z , Mauer and P i e s e r , A c t a C r y s t , 12-. 2 k 7 ( 1 9 5 9 )  (1957)  J . Chem. Phys. /3_3, 2 5 2 ( i 9 6 0 ) J • Chem. Phys.  S o l u b i l i t i e s o f Organic Compounds, 3 r d . Ed. V o l . 2 D. van Nostrand, New York ( 1 9 k l )  67.  12,  34-9 ( 1 9 5 9 )  2k.  Post, Acta Cryst,  25.  Pauling,  26.  K.B. H a r v e y ,  27.  H e r z b e r g , I n f r a r e d a n d Raman S p e c t r a , D. New Y o r k ( 1 9 k 5 )  28.  W i l s o n , D e c i u s and C r o s s , M o l e c u l a r V i b r a t i o n s , M c G r a w - H i l l I n c . , New Y o r k ( 1 9 5 5 )  29.  J e n k i n s and White,  o f t h e C h e m i c a l Bond, 3 r d E d . C o r n e l l , New Y o r k ( i 9 6 0 )  The N a t u r e  Private  communication.  Fundamentals McGraw-Hill  van Nostrand,  of Optics, 3 r d Ed. I n c . , New Y o r k ( 1 9 5 7 )  

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