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The Raman effect of cis and trans decahydronaphthalene Zotov, Gennady 1940

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THE  RAMM  EFFECT  OF CIS  M B - TRAM'S  35ECAHTBROHAPHTHALEHE by  Gennady Zotov  A. Thesis submitted i n P a r t i a l F u l f i l m e n t o f The Requirements f o r the Degree o f MASTER  OF  ARTS  i n the Department o f PHYSICS  „  THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1940  CONTENTS  Page Introduction I  e  II.  Til© 02?  « • • • « • • . « • • •  D e s c r i p t i o n o f Apparatus and Procedure ' 1. The Raman Tube . . . . . . 2. S p e c t r o g r a p h s Equipment .  5 5 5  3. E x p e r i m e n t a l Procedure . .  7  I l l u s t r a t i o n o f the Set-up 4. H e a t i n g System  9  . . . . . .  10  5. Source and Temperature Control . . . . . . . .  11  I l l u s t r a t i o n of the C i r c u i t III.  1  13  INTRODUCTION  I t i s only r e c e n t l y  1  t h a t Dr. W. F. Seyer, o f the  Department o f Chemistry o f the U n i v e r s i t y of B r i t i s h has succeeded  Columbia,  i n s e p a r a t i n g c o m p l e t e l y the two isomers, c i s  and t r a n s decahydronaphthalene.  H i s work  on t h e change i n  the s u r f a c e t e n s i o n s , d e n s i t y e t c , w i t h temperature o f these substances r e v e a l e d the p o s s i b i l i t y e i t h e r o f f u r t h e r subd i v i s i o n o f t h e c i s and t r a n s froms or o f changes i n s t r u c t u r e of the o r i g i n a l molecules as we go t o h i g h e r temperatures. I t was suggested by Dr. H. D. Smith, t h a t t h i s problem be a t t a c k e d by a study o f the Raman e f f e e t o f these isomers a t v a r i o u s temperatures.  The Raman spectrum o f deea3  l i n a t room temperatures has been s t u d i e d by s e v e r a l workers. These i n v e s t i g a t o r s , however, had no access t o t h e isomers i n the pure s t a t e , nor had they any knowledge o f t h e i r temperature behaviour.  There i s r e a s o n t o b e l i e v e , t h e r e f o r e ,  t h a t t h e i r work d i d n o t g i v e as much evidence o f the i n t e r n a l s t r u c t u r e of the d e c a l i n molecule as i s , perhaps, p o s s i b l e to obtain. In view o f t h i s f a c t t h i s r e s e a r c h was undertaken as, suggested by D r . H. D. Smith. 1.& 2. Seyer & Walker, J.A.C.S., 60, 2125, 1938, and more r e c e n t work. 3. J a t k a f , I n d . J . P h y s i c s , 9:545, Qo 1 15, 1935. Bonino, AcCi L i n c e i A t t i . 22 pp. 438-443, Nov.17, 1935, and other papers.  THE  RAMAN EFFECT OF  CIS  AFP  TRACTS  I.  DECAHYDROIAPHTHASE1E  Theory  I t was d i s c o v e r e d by Raman t h a t l i g h t i n c i d e n t on c l e a r substances i s not o n l y s c a t t e r e d t o produce l i g h t o f the same frequency as t h e i n c i d e n t r a d i a t i o n ( R a y l e i g h or c l a s s i c a l s c a t t e r i n g ) but t h a t new l i n e s appear i n the spectrum o f the s c a t t e r e d l i g h t having f r e q u e n c i e s t h a t a r e p e c u l i a r t o the s c a t t e r i n g substance. I t i s known t h a t a molecule o f any c h e m i c a l eom• J* pound c o n s i s t s i n g e n e r a l o f a d e f i n i t e number o f atoms o f d i f f e r e n t elements.  Because of the molecule's s t a b i l i t y i t  may be p i c t u r e d as formed from i t s c o n s t i t u e n t atoms i n a d e f i n i t e s t r u c t u r e i n space.  The atoms themselves, however,  v i b r a t e a t c e r t a i n p e r m i s s i b l e f r e q u e n c i e s governed by t h e i r number, mass and r e l a t i v e p o s i t i o n s w i t h r e s p e c t t o other members o f the m o l e c u l e .  Thus a molecule may have a c e r t a i n  energy because o f these i n t e r n a l v i b r a t i o n s i n which case i t i s s a i d t o be i n a c e r t a i n e x c i t e d energy s t a t e . Thus a photon, from a beam o f i n c i d e n t l i g h t ,  col-  l i d i n g w i t h a molecule i n a g i v e n energy s t a t e , may e i t h e r "" impart some o f i t s energy t o t h e molecule and be s c a t t e r e d by the m o l e c u l e w i t h l e s s energy, or i t may reduce an e x c i t e d  molecule t o a lower energy s t a t e "by talcing energy from i t , " and be s c a t t e r e d w i t h g r e a t e r energy.  T h i s i s shown s y m b o l i c a l l y  as f o l l o w s : -  ±  ^ V  i.e. .or  ^  =  =  -t>~% •= ^  y  /r  o  j ^ %  tz  :  # A ^  where i s the energy of the s c a t t e r e d  photon  /z i s P l a n c k ' s c o n s t a n t # i s the frequency o f the i n c i d e n t photon p i s the f r e q u e n c y o f the s c a t t e r e d  photon, and  V i s one o f the c h a r a c t e r i s t i c v i b r a t i o n a l f r e q u e n c i e s of the m o l e c u l e . The p r o b a b i l i t y o f g a i n o f energy by the photon i s much l e s s than t h e p r o b a b i l i t y ' o f energy l o s s , due t o t h e f a c t t h a t p r a c t i c a l l y a l l o f the m o l e c u l e s i n the s c a t t e r i n g substance are i n t h e i r normal, or l o w e s t , energy s t a t e .  Hence  i n g e n e r a l t h e r e are fewer Raman l i n e s , and these o f weaker i n t e n s i t y , due t o t h e energy g a i n than t o the energy l o s s o f the photon.  Summing up we have  f o r energy l o s s  — hpj  we have  A* > A  f o r energy g a i n  + h P,  we have  /^^<  z  \-  r  where i s t h e wavelength o f t h e Raman l i g h t , and i s the wavelength o f t h e i n c i d e n t  light.  L i n e s a r i s i n g from the most common type o f energy change are sometimes r e f e r r e d t o as S t o k e s ' l i n e s ( r e p r e s e n t e d by t h e  s u p e r s c r i p t "s";): w h i l e the other types are c a l l e d A n t i - S t o k e s ' l i n e s ( r e p r e s e n t e d "by t h e s u p e r s c r i p t "A.S'J),  1  We a l s o have  » L,A,  V  where I i s the i n t e n s i t y o f t h e l i n e . In order to' o b t a i n t h e v i b r a t i o n a l f r e q u e n c i e s o f the molecule t h e f o l l o w i n g i n f o r m a t i o n i s obtained from the spectrograms: The photographic  p l a t e b e a r i n g the spectrogram i s  measured up on a comparator i n such a way t h a t the d i s t a n c e of each l i n e .from a c e r t a i n l i n e of s h o r t wavelength, say the v i o l e t Hg l i n e , X 4047 A.IJ., i s obtained i n c e n t i m e t e r s . S i m i l a r l y another p l a t e w i t h Hg and. Fe comparison s p e c t r a i s measured, and by proper t r a n s l a t i o n t h e r e a d i n g s are c o r r e l a t e d as i f the Raman and the Fe s p e c t r a were taken s i m u l taneously.  This s u p e r p o s i t i o n of t h e Raman spectrum on t h a t  o f the Fe enables  the l a t t e r t o be used as a c o o r d i n a t e a x i s  f o r i t s wavelengths a r e known.  From the known v a l u e s o f the  Fe l i n e s the v a l u e o f a g i v e n Raman l i n e i s found i n terms o f wavelengths by i n t e r p o l a t i o n o f i t s measured v a l u e and the v a l u e s o f the Wo  c l o s e s t Fe l i n e s between which i t l i e s .  These wavelengths a r e converted i n t o f r e q u e n c i e s (or more conv e n i e n t l y i n t o wave numbers).  E s t i m a t e s of r e l a t i v e  t i e s o f t h e Raman l i n e s a r e a l s o made. .The data thus  intensiobtained  i s i n t e r p r e t e d by the a i d o f the t h e o r y o u t l i n e d above.  . •  Thus w i t h t h e knowledge o f p o s s i b l e v i b r a t i o n a l frerquencies  of the molecule  and o f t h e approximate s t r u c t u r e of  the molecule i n f e r r e d "by chemical c o n s i d e r a t i o n s , or by a mathematical treatment  of the moleoule as a many-body problem  i n mechanics, employing methods s i m i l a r t o those developed by Bennison and o t h e r s , a more d e t a i l e d model o f the molecule  may  be c o n s t r u c t e d . An.intense  monochromatic source of l i g h t must be used  t o produce w e l l d e f i n e d s t r o n g Raman l i n e s t h a t are not  obli-  t e r a t e d by o t h e r l i n e s i n the spectrum of the i n c i d e n t l i g h t . Otherwise i f the source be weak i t i s i m p o s s i b l e t o o b t a i n Raman l i n e s w i t h i n reasonable p e r i o d s of time; and i f the source c o n t a i n s s e v e r a l i n t e n s e l i n e s i t i s d i f f i c u l t t o d e t e r mine from which i n c i d e n t l i n e a g i v e n Raman l i n e  arises*  The Eg are comes v e r y c l o s e t o being the source.  ideal  I t s spectrum, has o n l y two l i n e s v i z . , A A 4 0 4 7 , 4358  i n the r e g i o n A A4000-5000 A.U. g i v e r i s e t o Raman l i n e s .  of i n t e n s i t i e s g r e a t enough t o  Moreover t h i s r e g i o n i s remarkably  f r e e from other l i n e s of l e s s e r i n t e n s i t y and these may  be cut  out of the spectrum of the i n c i d e n t l i g h t by the use of special filters.  This f i l t e r i n g a l s o l e s s e n s the  continuous  background p r e s e n t i n t h i s r e g i o n o f the Hg a r c spectrum.  - 5 III.  D e s c r i p t i o n o f Apparatus and Procedure  The  standard method o f o b t a i n i n g good Raman p l a t e s  c o n s i s t s o f r e c o r d i n g s p e e t r o g r a p h i c a l l y the l i g h t  scattered  by the substance i n a d i r e c t i o n a t r i g h t angles t o t h a t o f the incident l i g h t .  Deviations  from standard  technique,  however,  were found n e c e s s a r y i n t h i s , work, and because of t h e i r . i n t e r e s t and importance are d e s c r i b e d  below.  I . The Raman Tube The Raman tube (46) c o n t a i n i n g the l i q u i d t o be s t u d i e d i s designed e s p e c i a l l y f o r work a t v a r i o u s tures.  I t c o n s i s t s o f a double-walled  tempera-  c y l i n d r i c a l pyrex tube  w i t h o u t s i d e dimensions of 4.1 cm,* diameter and 14*8 cm. length.  The i n n e r tube t h a t holds t h e l i q u i d being  investi-  gated i s 2*6 cm, i n diameter and 11.1 cm. l o n g w i t h a c a p a c i t y of 60 c.e. I t s c o n s t r u c t i o n i s shown i n d e t a i l b y the s c a l e diagram designated The  Fig. I.  s i d e s o f the tube from A t o B and G t o 3 are  blackened w i t h lampblack mixed w i t h s h e l l a c and a l c o h o l and the ends are covered except f o r spaces 13? and GH of 1 cm. diameter.  A r i n g (I) i s a l s o p a i n t e d around the base of the  thermometer w e l l .  The b l a c k coats prevent the admission and  r e f l e c t i o n of s t r a y l i g h t . At the back GrH a s m a l l plane m i r r o r  (8) i s p l a c e d  t o r e f l e c t back along the a x i s i n t o the s p e c t r o g r a p h the s c a t t e r e d l i g h t p r o c e e d i n g away from t h e i n s t r u m e n t .  The  1  source, a Hg arc (48), i s p l a c e d as shown, and the l i g h t i s focussed on the a x i s of the Raman tube (46.) by means o f a l u m i num  reflectors viz.,  drical reflector  a parabolic reflector  (49) and a c y l i n -  (50) i n d i r e c t c o n t a c t w i t h (46).  A g l a s s c e l l (47), 10 x 1 x 1 cm. duced between (46) and p r o t e c t the c e l l ,  i n size, i s intro-  (48) t o h o l d the f i l t e r s o l u t i o n .  t o l e s s e n e v a p o r a t i o n of the f i l t e r  To  solution  and t o prevent h e a t i n g up of the l i q u i d by the arc, a copper. U-tube, through which c o l d water i s r u n n i n g c o n t i n u o u s l y , i s immersed i n the f i l t e r s o l u t i o n t o a depth j u s t c l e a r i n g the top o f the Raman tube.  The heat from the are i s thus  absorbed  by the f i l t e r s o l u t i o n and t h e n c a r r i e d away by the c o l d  water.  Source A mercury a r c c o n s i s t i n g of a q u a r t z tube w i t h merc u r y p o o l e l e c t r o d e s i s used as a source.  The arc i s equipped  w i t h aluminum f i n s f o r r a d i a t i o n o f heat generated d u r i n g i t s operation. the tube.  The arc i s s t r u c k at 3.2  amps, w i t h 24 v o l t s across  The c u r r e n t then f a l l s t o 1.6  amps, a t 66 v o l t s as  mercury g l o b u l e s are evaporated from the s i d e s of the  tube.  On the c o m p l e t i o n of e v a p o r a t i o n the c u r r e n t r i s e s t o 1.8 at  60 v o l t s .  An a i r stream i s t h e n turned on, and  p l a y i n g on the n e g a t i v e end of the q u a r t z tube.  2.8  amps, at 30 v o l t s a c r o s s the a r e .  maintained,  The.flow of  the stream i s a d j u s t e d so t h a t the amperage reaches at  amps,  and remains  Under these c o n d i -  t i o n s the a r c operates f o r an i n d e f i n i t e p e r i o d o f time.  Filter Owing t o t h e f a c t t h a t mercury a r c s g i v e a c o n t i nuous background f o r l o n g exposures i n t h e r e g i o n AA.4360 4800 A.U., which would c u t out t h e weaker Raman l i n e s , a f i l t e r i s i n t r o d u c e d between t h e source and the tube. S u f f i c i e n t fluorescene, d i s s o l v e d i n a small quantity of a l c o h o l , i s added t o water i n the g l a s s c e l l t o c u t out most o f t h i s background without  A  a p p r e c i a b l y c u t t i n g down t h e i n t e n s i t y o f  4916 A.F.  Z. Spee t r o g r a p h i c Equlpment To o b t a i n the spectrograms Eastman photographic . p l a t e s o f type 105-0 were u s e d .  These p l a t e s were  by t h i s company e s p e c i a l l y f o r Raman spectroscopy.  introduced They were  developed i n D - 19 developer and f i x e d i n a F 5 s o l u t i o n . The  s p e c t r o g r a p h used was. a H i l g e r Constant  t i o n ins t r a ^  Devia-  w i t h a d i s p e r s i o n of 17 A.TJ. p e r mm. i n the  region u t i l i z e d . 3. E x p e r i m e n t a l The  Pr o cedure s c a t t e r e d l i g h t from the Raman tube i s focussed  on t h e s p e c t r o g r a p h shown i n F i g . I I .  slit  (1) by the condensing l e n s ( 2 ) , as  I n order t o p r e v e n t l i g h t r e f l e c t e d from  the s i d e s o f t h e Raman tube from r e a c h i n g the s l i t o f the spectrograph  two b l a c k e n e d m e t a l diaphragms ( 4 ) , (5) w i t h  openings of 1 em, diameter a r e i n t r o d u c e d ; t h e condensing l e n s  i t s e l f i s blackened a l s o except f o r a c e n t r a l p o r t i o n of the same s i z e as the diaphragm  openings.  I n order t o decrease the exposure times g r e a t care was t a k e n t o use t h e maximum•amount of s c a t t e r e d energy.  For  t h i s reason t h e alignment o f the o p t i c a l system deserves part i c u l a r a t t e n t i o n , t h e procedure being as f o l l o w s : A s m a l l plane m i r r o r (3) was i n s e r t e d between t h e condensing l e n s (2) and the f i r s t diaphragm  (4) a t an angle  of 45° t o t h e d i r e c t i o n o f t h e s c a t t e r e d beam.  The p o s i t i o n s  o f t h e diaphragms 14) and (5) were changed i n t h e i r r e s p e c t i v e •planes by the o b s e r v e r , w h i l e v i e w i n g i n ( 3 ) , so t h a t a s e t of c o n c e n t r i c r i n g s (15) were formed by t h e openings  (4), ( 5 ) ,  (6) and t h e i r r e s p e c t i v e images ( 1 2 ) , (11), (10) i n the m i r r o r ( 8 ) , w i t h the image ( 1 3 ) , o f the e y e , ( 9 ) , a t the c e n t r e . This ensures an' unhindered path of t h e s c a t t e r e d beam w h i l e p r e v e n t i n g any s t r a y l i g h t from r e a c h i n g the: s p e c t r o g r a p h . W i t h the m i r r o r (3) now removed, a p i e c e o f t r a n s l u c e n t paper was p l a c e d d i r e c t l y i n the p a t h o f t h e beam and i n c o n t a c t w i t h the diaphragm  s i d e of the l e n s ( 2 ) , and the  l e n s was moved i n i t s plane u n t i l the c e n t r a l p o r t i o n was conc e n t r i c w i t h the c r o s s s e c t i o n of the beam.  The paper was  then taken away and the s p e c t r o g r a p h was moved a l o n g the d i r e c t i o n o f the beam t o a p o i n t where a sharp image on the slit  (1) was s e c u r e d .  The image was made s l i g h t l y l a r g e r  than t h e . s l i t t o ensure t h a t n o ' l i g h t r e f l e c t e d by the w a l l s of the Raman tube be sent through the s l i t .  The  adjustment o f the s p e c t r o g r a p h was c a r r i e d out  by the standard method of s e t t i n g the c o l l i m a t o r  for p a r a l l e l  l i g h t , and the f o c u s s i n g o f the s p e c t r a l l i n e s c a r r i e d out by the a i d o f the Foucou.lt shadow t e s t . was  The condensing l e n s (2)  chosen o f such a f o c a l l e n g t h (F = 2.54 cm.) that the  l i g h t from the sharp image ( o f a b r i g h t  o b j e c t of the r e q u i r e d  s i z e - 1 cm. diameter - p l a c e d at the c e n t r e of the Raman tube) on the s l i t j u s t f i l l e d the c o l l i m a t o r  lens.  The white  from a broken Beckmann thermometer served as a b r i g h t  A s t r i p of sheet aluminum i n s e r t e d  object.  i n the Raman tube  was  used a l s o t o advantage as a b r i g h t  the  l i g h t from the Hg a r c o u t s i d e , f o r t h e F o u c o u l t t e s t .  T h i s was e s p e c i a l l y d e s i r a b l e  scale  s o u r c e , by r e f l e c t i n g  w i t h t h e Hg b l u e l i n e , A 4358,  and  the v i o l e t l i n e , A 4047, f o r t h e i r i n t e n s i t i e s were t o o  low  for s a t i s f a c t o r y v i s u a l observation.  - 10 U s i n g w h i t e l i g h t , w i t h such a r e f l e c t o r i n p o s i t i o n , the  f o l l o w i n g procedure was adopted t o throw the maximum energy  on t o t h e p h o t o g r a p h i c p l a t e : W i t h the s l i t open wide and a p i e c e o f t r a n s l u c e n t paper a t the condensing l e n s the s p e c t r o g r a p h was r o t a t e d about a v e r t i c a l a x i s and l e v e l l e d by the observer u n t i l he c o u l d see through the camera l e n s (17) a c o l o r e d spot of l i g h t a t the c e n t r e o f t h e "frame" formed by t h e edges o f t h e p r i s m (16) n e a r e s t t o the camera l e n s . To g e t maximum energy f o r minimum w i d t h of t h e spect r a l l i n e , t h e s l i t was f i r s t c l o s e d , and then s l o w l y opened w h i l e i t s image was b e i n g observed a t t h e f o c a l plane o f t h e camera (18) by t h e eye w i t h a narrow c y l i n d r i c a l l e n s (F = 1 em.) p l a c e d j u s t i n f r o n t o f i t .  The a x i s o f the c y l i n d r i c a l  l e n s was p l a c e d p e r p e n d i c u l a r t o the image ( o r the s p e c t r a l line).  F o r t h i s purpose Hg l i g h t was used w i t h a l l o b s t r u c -  t i o n s such as t h e t r a n s l u c e n t paper and m i r r o r removed.  The  l i n e appeared o f l a r g e and c o n s t a n t w i d t h , b u t shaded, as shown i n ( 2 0 ) , t h e shadow d i s a p p e a r i n g a c r o s s the image i n t o the  s i d e on w i d e n i n g the s l i t .  The proper w i d t h was d e t e r -  mined a t t h e s p a c i n g o f t h e s l i t where the shadow had j u s t disappeared. 4. H e a t i n g System For  exposures a t h i g h temperatures the l i q u i d i n the  tube was r a i s e d t o the r e q u i r e d temperature by p a s s i n g a stream of heated a i r through the j a c k e t around the Raman tube.  The  - 11 stream was s u p p l i e d by a four-vane water c o o l e d compressor r u n at 1725 r e v s , per min. by a 1/8 H.P. A.C. motor drawing 3 amps and heated on being passed through a h e l i c a l copper tube i n an oven. A.C,  The oven was heated by an e l e c t r i c r e s i s t e r (27) on The upper l i m i t o f the c u r r e n t was determined by the  s e t t i n g of the r h e o s t a t (R) and t h e h e a t i n g c o n t r o l l e d by a stove thermostat (30) on a U.C. r e l a y ( 3 2 ) .  The upper  limit  of the c u r r e n t used was a safeguard t o prevent o v e r h e a t i n g i n case o f f a i l u r e o f the r e l a y . . Source and Temperature, C o n t r o l A l t h o u g h the s t r o n g e r Raman l i n e s of t h e d e e a l i n isomers c o u l d be photographed  i n 30 or 40 minutes, much l o n g e r  exposures (144 hours) were taken i n order t h a t many o f the weakest Raman t r a n s i t i o n s might be r e c o r d e d on the s p e c t r o graphic p l a t e .  A study o f these f a i n t e r l i n e s was n e c e s s a r y  i f any s l i g h t changes i n m o l e c u l a r s t r u c t u r e w i t h temperature were t o be i n v e s t i g a t e d .  Therefore i n order t o m a i n t a i n the  temperature of the" l i q u i d a t a c o n s t a n t v a l u e and t o guard, from any p o s s i b l e f a i l u r e s i n e l e c t r i c a l s u p p l y or other cont i n g e n c i e s the f o l l o w i n g e l e c t r i c a l c i r c u i t was used as shown in Fig. I I I . The motor (45) r u n n i n g the compressor which c i r c u l a t e d a stream o f a i r (shown by the d o t t e d arrow) over t h e * h e a t i n g element  (27) t o heat the l i q u i d i n the Raman tube (26)  was on the 1 1 0 - v o l t A.C. l i n e .  I n the event o f the compressor'  - 12 f a i l u r e the p r o t e c t i v e fuse (43) was c u r r e n t i n the motor c i r c u i t ,  "blown" "by the growing 1  To a v o i d the "blowing ? due  to  the c u r r e n t surge on s t a r t i n g , the motor the by^pass s w i t c h was  c l o s e d f i r s t , the fuse s w i t c h (42) was  then (44) was  closed next,  (44)  and  opened.  Since, oh the s t o p p i n g of the compressor, the  liquid  i n the Raman tube; would c o o l t o room temperature i t was s a r y t h a t the arc be cut o f f i n order t o prevent of the spectrum due  neces-  superposition  t o the exposure a t the room temperature on  the one being t a k e n at h i g h e r temperatures. the primary of the t r a n s f o r m e r  (40) was  For t h i s purpose  put across the motor,  at 110 v o l t s , but i n s e r i e s w i t h the f u s e , to a c t u a t e the. r e l a y (39) on i t s secondary a t 500 v o l t s .  When the motor was  the c o i l of the r e l a y h e l d i n suspension which was  the i r o n yoke (38) t o  a t t a c h e d the mercury s w i t c h (37) c l o s i n g the B.C.  m a i n t a i n the arc (25). was  running  On, the "blowing  r e l e a s e d , b r e a k i n g the B.C.  Switch  11  of t h e . f u s e the yoke (41) was  introduced f o r  s a f e t y w h i l e working on the adjustment of the r e l a y .  When  h e a t i n g was not r e q u i r e d ( i . e . (45) not used) the a r c was t a i n e d by s h o r t i n g the mercury s w i t c h by means of key The a r c (25) was  on the 110 v o l t s B.C..  w i t h a p r o t e c t i v e r e s i s t a n c e (35) which was 2.8  to  main-  (36).  line i n series  adjusted to read  amps, on the ammeter (21) when o p e r a t i n g under steady con-  ditions. (32) and  Taps on (35) s u p p l i e d v o l t a g e t o operate (33) .  Relay  (33) operated  the r e l a y s  the e l e c t r i c c l o c k  (34)  which stopped on the f a i l u r e of the arc or of the compressor  - 13 thus r e c o r d i n g the exposure time.  Relay t r o l l e d the A.C. (28).  (32) i n s e r i e s w i t h the thermostat c u r r e n t i n the heater  (30) con-  (27) read by the ammeter  The h y b r i d s w i t c h (31) w i t h the s h o r t i n g key  (29)  was  used to t e s t the working of (32), to s e t (30) f o r o p e r a t i o n at the r e q u i r e d temperature, and t o speed up i n i t i a l without d i s t u r b i n g the s e t t i n g on  (30).  heating  - 14 I I I . :; R e s u l t s :  A number o f e x c e l l e n t Raman spectrograms have been obtained  and s e v e r a l o f these are reproduced i n P l a t e s I , I.I,  and I I I . P l a t e I shows the Raman spectrum obtained  with c i s  decanaphthalene a t 20° C..,'while P l a t e IT was obtained  with  the same l i q u i d maintained a t a temperature of 65° C., t h a t i s , at a p o i n t w e l l above the " t r a n s i t i o n " temperature observed by Seyer*  P l a t e I I I i s t h e Raman spectrum o f the t r a n s modi-  f i c a t i o n m a i n t a i n e d a t 20° 0.  A l a r g e number o f Raman l i n e s  were observed i n a l l three spectrograms, and the f i r s t columns of Tables I and I I g i v e the wavelengths of these l i n e s , i n Angstrom u n i t s .  The'second columns of each t a b l e give; t h e f r e -  quency numbers c o r r e s p o n d i n g t o these wavelengths, w h i l e the t h i r d and f o u r t h columns g i v e the AV.^'s or Raman frequency: s h i f t s from the two i n c i d e n t l i n e s  X4047  A. and A 4358 A.  In order to f a c i l i t a t e an examination of t h e s p e c t r a obtained,  t r a c i n g s were obtained  of P l a t e s I , I I , and I I I .  w i t h a M o l l micr©photometer  Copies o f these t r a c i n g s are r e p r o -  duced here i n P l a t e s IV, V, and V I .  An examination o f P l a t e s  I and I I I o f t h e c i s and t r a n s isomers, along w i t h t h e i r  cor-  responding mierophotometer t r a c i n g s shows t h a t there are v e r y great d i f f e r e n c e s i n the Raman s p e c t r a o f the two m o d i f i c a t i o n s a t room temperature.  From the wavelength and frequency  d i f f e r e n c e s g i v e n i n Tables I and I I , one sees t h a t many l i n e s appearing i n the spectrum o f the c i s isomer do n o t appear i n t h a t o f t h e t r a n s m o d i f i c a t i o n , and that many " t r a n s " f r e -  * •  - 15 T  quencies are absent i n the ' c i s " spectrum.  I n both s p e c t r a  however a number of new Raman l i n e s are found t h a t have not been r e c o r d e d by p r e v i o u s w o r k e r s .  A f u r t h e r study o f these  new f r e q u e n c i e s may f u r n i s h v a l u a b l e i n f o r m a t i o n c o n c e r n i n g the s t r u c t u r e o f the " c i s " and " t r a n s " m o d i f i c a t i o n s o f the decahydronaphthalene m o l e c u l e . A c a r e f u l comparison o f P l a t e s I and I I and t h e i r microphotometer t r a c i n g s i V and Y y i e l d s p o s s i b l y t h e most i n t e r e s t i n g r e s u l t o f t h i s r e s e a r c h ; namely,- d i f f e r e n c e s are observed i n the two s p e c t r a t h a t i n a l l p r o b a b i l i t y i n d i c a t e a change i n the m o l e c u l a r s t r u c t u r e of c i s decahydronaphthalene as i t i s taken from 20° C. t o 65° C,  I f t h i s i s so, we have  an e x p l a n a t i o n o f the sudden changes observed i n the p h y s i c a l p r o p e r t i e s o f t h i s isomer i n the neighborhood o f 55° C.  A  s i m i l a r change f o r t r a n s decahydronaphthalene a t 85° G. i s i n d i c a t e d b y Seyer's work and a study i s b e i n g made a t the present time of t h i s isomer a t temperatures above and below this transition point.  Table I ( C i s )  #  X  1 2 3 4 5 6 7 8 . 9 1G 11 12 13 14 15 16 17 18 19 20' • 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54  4132.8  :  A  4173.6 4190.9 4204.6 4213.1 4218.8 4223.6  4255.9 4264.9 4268.1 4275.5 4280.5 4297.5 4427.3 4442.3 4476.0 4504.2 4514.7 4523.1' 4526.3 4534.6 4542.2, 4550.5 : 4552.9 4559.4 4565.8 4571.6 4575.6 4581.3 4584.5 4587.5 4593.0 4602.9 4608.3 4614.1 4624.1 4628.3 4631.1 4635.0 4651.2 4655.6 4929.0 4940.0 4948.6 4960.4 4976.7 4980.4 4987.4 4993*6 4999.0 5028.2 . 5050.3 5127.2  r  715.5 752 .0 850.9 928.6 97 6.6 1008.6 1035.6 1066.9 121*3 e 2 1264.8 1282.3 1322.9 1350.2 1442.6 2124.6 2200.8 2370.3 2510.1 2561.7 2602.8 2618.5 2658.9 2695.8 2735.9 2747.5 2778.8 2809.6 2837.3 2856.4 2883.6 2898.9 2913.1 2939.2 2986.0 3001.5 3038.8 3086.6 3105.2 3118.3 3136.4 3211.6 3221.9 4423.0 44#8.1 4503.3 4:5131 e «3 4617.4 4632.3 4660.4 4685.4 : 4707.0 4823.1 4910.1 5207.0  357.2 433.4 602.9 742.7 794.3 83,5.4 851.1 891.5 928.4 968.6 980.1 1011.4 1042.2 1069.9 1089.0 1116.2 1131.5 1145.7 1171.8 1218.6 1244.1 1271.4 1318.2 1337.8 1350.9 1369.0 1444.2 1464.5 2655.6 2700.7 2735.9 2783.9 2850.0 2864.9 2893.0 2918.0 2939.6 3055.7 3142,7 3439.6  Table I I  f  A  1 2.  4113•6 4128,3 4171.7 4189.3 4193.7 4221.5 4225.6 • 4241.-8 . 4245*5 4257.8 4261.9 4265.0 4273.7 4278.4 4282.0 4297.3 4415.1 4418.4 4453.4;4495.7 4524.0' 4550.6 4533.7 4541i4 4546.8. 4554.9 4568.2 4571.9 4681.2 4586.7 4607.0 4617.0 4623.6 4630.9 4634.9 4636.1 4651*0 4928.0 4960.3 4972.1 4977.3 4986-. 0 4993.0 4997.6 5011.3 5030.1 5128.9 5178.3  . 4 5., 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49  (Trans) A V 402.6 489.2 •741.1 841.8 966.8 1023.8 1046.8 1137.1 11.57.6 1225.7 1248,3 1265,3 1307.0 1338.6 1358.4 1441.5 2062.2 2079.1 2256.9 2468.1 2607.2 2639*4 2654.5 2691.9 2718.1 27 62.0 2821.1 2838.8 2883.2 2909.3 3005.4 3052.4 3083.3 3117.4 3136.0 3141.6 3210.7 4418.8 4550.9 4598.8 4619.8 4654,8 4682.9 4701.4 4756.0 4830.6 5213.5 5399.4  294.8 311.7 589.5 700.7 839 * 8 872.0 887.1 950.7 994.6 1053.7 1071.4 1115.8 1141.9 1238.0 1285.0 1315.9 1350.0 1368.6 1374.2 2661.4 2785.5 2831,4 2852.4 2887.4 2915.5 2934.0 2988*6 3063.2 3446.1 3652.0  PI ate I  Plale'JL'  Plate  7 late  71/  VL  

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