Sanyal, S B

Sirkar, S C

English

IACS Institutional Repository

INFLUENCE OF TEMPERATURE ON THE INTENSITIES OF RAMAN LINES DUE TO SOME ORGANIC LIQUIDSBy  S. C. SIRKARANDS. B. SANYAL{ K c i c i i ' t ' d   ^ i ' ^ c l o b r r  i q i )^ABSTRACT i'lir intcii.sit los of n frw Rnniaii liiu s of ficii/yl ah^ olio], hcMiz} ! aiiiinr ami l)cn7oyl I’lilfU'iMc at llic rniaii kMin>eralurr ami at iimlar ti‘inpiaatim\s, a f m s ' h c l - a w  tlic hoilinn pjiiils of the lifiiiitl,, have bt'Cii iiicasunal (jitanlilaliu l\, UMim nuTliod of plioti>t;rapIn\’ spu iioplioloim h y. Tl ha,s bccM observed tbal in Hk eas«'(vI Ibe linos (Oo, 71J4 and luo' ol l)vn/yl alrobo] and of llio liiioi ni’^ of bon/^ oyl oldoi idi , (lie inlonsitios innoaso will) tilt' iiiori ase ol leinporatiii e in aroordam o with tlio jncahVlions of Hu* p()1m] isnliilily theory fn Hie < nse of Ihe Raman lines of lai i.^ er fio(|nrm'y-shifts the intensities .are oliServed to reniain alinosl (vaistaiil with the inerevase in Hie leinperatin'e of the liijiiids as imliealed Ijy Hie said tlieor\.J N T R O D U C T l O N40It is WL'll known tliat according; to the llieoi}' pul forward I>y Plac/ek ( ip ji)  llie intensity ol the Raiiiaii lines of frequencies v—r , sliould increase vvitli thetemperature in accordance witli the relation J (I'-i-,) '"V I f  j — " '^''1 S '/' ) (1)Several attempts have keen made to lest the correctness of these predictions of the theory besides those ie«ardiu}> the ratio of the intensities of the Stokes and auti-Slokes Kaman lines. Before this theory was pnlilished, Lajidsberi; and Mauddstam (iq.v.i) had investigated the inteu.sities of Raman line 465 of quart?: at temperatures 2:>°C and 537°C. 'I'hey observed that the intensity at the higher temperature was 1.2Q limes that at the lower temperature. The same problem was also studied qualitatively by Ney (1931) who reported that the influence of the increase of temperature on the intensities of the Raman lines of quartz was different for different Raman lines, so that the relative intensities of the Raman lines on the vStokes side were observed to change with the increase of lemj)erature of the crystal. The micropholometric curves of the spectrogram reproduced by Ney show that the line 4D5 of (piartz shifts to .15b and its intensity diminishes considerably at the higher temperature. Careful ex'aniination of the records, however, also shows that this line becomes iinich l>roader at llio higher temperature than at the lower temperature. Orjistcin and Went (1035), liesides measuring the ratio of the intensities of Stokes and anti-Stokes Raman lilies, also investigated quantitativ'dy the chauges in the intensities of tlie lines -• -niSSl* VI310 S, C. SirJ^ar and S. B. Sanyal1 .7  and 165 of quartz with the change of temperature of the crystal from 90'"K to 4;io' K, and of the lines 153, 714 and 10S8 of calcite with the changeof tenipcratuie iioni 293 K to 426* !^ .^ They observed that in the case of both the Raman lines of (jnarlz mentioned above the intensity diminished with the increase of temperature, and the same effect was observed also in the case of the three lines 155, and 7 T4 of calcite, while the intensity of the line 10S8 remained constant with the change of temperature. It has not been uientioucd by these authors, however, whether they measured tlie integrated intensity or the peak intensity. It has been pointed out above that tlie microidiotometric records reproduced by Ney indicate a broadening of the line 465 at the higher temperature. Hence the intensity is smaller at the higher temperature than at the lower temi)craturc if the peak intensity is considered, but if the integrated intensity were taken into consideration the conclusion would probably bedilferent, at least for this line.The same problem was investigated in the case of some crystals more recently by Veiikateswaihi (1941). He hist studied the intensities of the Raman lines 4(>3 of quartz, lob^ of sodium nitrate and 313 of mercuric chloride at dineieiit lemperatiiies and observed in eacdi case a diminulion in intensity witli the increase of tcmpeiatuic up to about 403 K . He mentioned that the width of the lines did not increase whth the increase in temiierature and hence only the ]jeak intensities were measured. In a later piper Venkateswarlu (194c) re[u)r1ed the results of similar investigations in the case of calcite. In this case also the intensities of the Raman lines eSu, 710 and 10S5 of calcite wereobserved to diminish with the increase of temi)eratnre from 303 K up to 493”K. It lias lH*en mentioned by him tliat the lines u^ ere of same width, at the lower and higher leinpcratiires and so only tlie [>eak intensities w^ ere nieasured. If, however, the s])cctrogram reproduced by him be examined carefully it is found that tlie line c8o of calcite becomes apiireciably broader at higher temperatures. Besides this, the intensities of the Rayleigh lines also appear to diminish at the higher temperatures almost in the same ratio as those of the Raman lines mentioned above. If this be not due to any systematic diminution of the intensity of the incident light at higher temperatures, it is difficult to understand huw^  the intensity of the Rayleigh scattciing diminishes with the increase of temjieratuic, because experimentally it lias been observed by Uandsberg and Mandelstam (1930) that in the case of quartz the intensity of the Rayleigh scattering is proportional to the absolute temperature of the crystal.I'hc validity of relation (i) in the case of liquids was first tested by Anantha- krishiian (193^) who investigated the intensities of the Raman lines of CCU at temperatures ranging from to 200*^0. He observed that the integrated iuleiisity of the Stokes Raman lines of CCli does not increase with the increase of teiiiperature. He has also discussed various other changes, c.g., broadening, and change of fiequency of the Rainau lines which are observed with the increase of temperature as well as the difficulties which are experienced in making the experimental conditions identical at both high and low temperatures.Besides the difficullies mentioned hy Aiiaiithakdslman, . ..e,, tlie w ideiiing of the lines, the change of refractive index of the liquid e.iusuig a change in the inteusity of the iiicicleiil liglit, and the expansion of Ihc litpiid, there is another difficulty not iiieutioned by him, namely, the birefi iip^enee (>f the window of the tube containin^  ^ the liquid caused by hi;,>h i)ressuresde\eloped\\henll)e liquid is heated much above its boilin- point in the closed tul)e. The present investigation was undertaken with the object of testing the validity of ielation ii) given by Plae/ek in the ease of a few aromatie liquids luiving high boiling ]>oints so that no high pressure could be develoi)ed inside tlie tiilie containing them. vSomc of the other sources of error have also been taken into aeconnt as will be evident from the discussions of the resnlts.Jv X 1* p: R 1 IM !•: N 'J' A hInfluence of Temperature on the Intensities of Ram an Lines 311The liquids chosen for the present investigation are ben/y] alcohol, benzyl- amine and benzoyl chloride. These were obtained from Kalilbauin s sealed bottles. They were distilled in varunm before use. The experimental tube had a plane window  ^ and its other end w^ as I:ient into the form of a horn terminating in a bulb to hold the increased volume of licjuid at the higher temperature. A narrow’ tube was joined to the bull) and after the tube w as filled wdth thu distilled liquid upto a level beiow' the bottom of the bulb, the tube was evacuated and a constriction in the narrow  ^ tube was sealed olT. 'J'he heater consisted of a few^  coils of nichronie wire enclosed between twa) coaxial brass cylinders, insulated by asbe.stos and a wdiidow wms left open iiarallel to the length of the cylinder. This gap w^ as closed by a transparent thin sheet of mica. The lube was thrust into the heater through one of its month and tlie scattered light was ol)sei ved through the other mouth, the open regions of which were closed with asbestos ])acking. Light from a horizontal Heraus type mercury arc condensed by a five-inch gla.ss condenser w’as used as the incident light wliicli jiassed througli the mica window. The arc was started before the commencement of the exposure and was allowed to run at a stretcli undisturbed throughout llie exposure for both the hot and the cold liquid. As the room was closed on all sides, the intensity of the arc did not fluctuate during the exf)osure. Also, as the liquids were heated upto temperatures a few^  degrees below their boiling points, the plane windows of the experimental tubes did not develop any extra birefringence at the higher temperature. The levels of tlie liquid in the tail of the exijerimental tube at the room temperature and at the higher temperatures W'cre noted and from the measured volumes upto these levels the increase in the volume of the liquid was estimated. The temperature w^ as measured with a mercury thermometer w'hicli was placed in contact wu’th the glass lube containing the liquid inside the healer.The Raman spectrum for tlic hot liquid was photographed first in order to lake into account any chemical change in the liquid which might take place with the rise of temperature. The current in the heater was switched off and3/2 5. C . Sirl^ar an d  S.  6 .  S a n y a ltlic spcctimii for the cold liquid was next phc^lographcd on the same jdate using the same time of exijosure as for the hoi liquid. A few intensity marks were also f)l)taiiied on the same plate using different known widths of the slit of the sjjec'trograph and light from an ordinary tungsten filament lanq) reflected by a |>ie('e of lliiek white ]>a])er as source of continuous radiation. A Hilger two- prism speetr(;gia]>li oi higli liglit-gathci'ing i>ower was used. IMicrophotometric records oj the spectrogiams were obtained with tlie help of a Ripp and Zonen self-recording iiiicrophotometer. The intensities ol the background on both sides of eacli line relative to the unexposed portion of the plate were determined in the case of each line in question will] the help of the blackening log.-inten­sity curves and were subtracted from the total intensity of botli the background and llie line in order to obtain the intensity of the line. In tlie case of each li(liiid only a selet'tcd few Raman lines have been taken into consideration. Also, in Older to investigate the question whether the intensity oi the Rayleigh lines increases witli the increase of the temperature of liquids, the intensities of the Imc A.|(ii6 recorded at tlie t wo temperatures have been compared, J he results arc discussed in tlie following section.R I<: S 11 h S A N D  D I S C l) vS S n ) NThe ratios of intensities of particular Raman lines at the higher temperature to the corresponding intensities at the room temperature as deduced frpm the blackening produced on the plate by the lines with the help of the blackening log-intensity curves for the corresponding wavelengths are given in column 2 of tables 1, II and HI. These have been corrected foi the dilatation of the liquid at the higher tcmperaliiies. 'I'he con ection factors as calculated Irom the observed incicase of volume of the liquids have been found to be approxi­mately i-oq, 1 .oy and i oS for beir/yl alcoliol, benzoyl chloride and benzyl amine respectively. The corrected values of the intensities are given in column of the tables. These intensity-ratios as calculated from relation (1) arc given in the last column of the tables. ( )nly Raman lines excited by the Hg line A.135S have been investigated in each case. The ratio of the intensity of the Rayleigh line A.p)i() at the higher temperature to that at the room temperature as deduced from the speetrograins has also 1)eeii entered in the last column of each of the said tables. The widths of the lines investigated arc observed to remain unchanged at the higher temperatures and therefore the peak intensity has been measured in cadi case.It can be seen from tables* II and 111 that the intensity of the Raman lines bio, 79^ 1 and 1000 of benzyl alcohcl and 1003 of benzoyl chloride increases with the rise of temperature of the liquids and the increase observed in each case is fairly in agreement with that predicted by the theory within experimental error. In the case of the lines rooi and 3055 of I^enzyl amine the corrected intensity ratio is slightly lower than the calculated value, but this diminution is probably due to some experimental error, which taking into considerationInfluence of Tempcraiure on ihe Intensities of H om an L in es  3t3T aku ; IB l'Ii/ v] iiK'olu)]. 15- ]\ .|;S K1jline. j!1 m  1 M !o1 ISL I \’ClliIjliiCl a i cc It (1 K I  dilatalii 111 t alt 111.lit i]C - ( J I O 1 1.1 () ! J -1331 H ) 1 1 .< 'M j 1 U^ir-io( h,io.yO 1 J .»>3 ; J  .'13oajo n 08 ■ J  r.oRayleigh linel^ylh I  01 iTAlii.K I JI 5eii/.(‘yl <.'lik>ridc • H. 1>. .47u " KRaman line. I jM' Uuj;i nhsu VC <1Ijoii» on c ( It (1 /(»t (lilatalifjii. taUnlalcd1 1 11 ng J<’-J 592 1i11 -UCl.|3^c b7 »),yr) ; 0 g8 j  J  ()MRayleigh liiir 491O i .i 1iKiUii1T a b u c  1 1 1Benzyl amine. n .  V. 457°KRainnJi line. 1 3^6/1303 observed.1^ 430/^ 303corrected for dilatation.I43C/J3O3 caU’uJatt d.f - I O O I j  o.go 0.97 1 .02CJ-3055 0 .8 8 “ •95 J . O t JRayleigh line 4916 1.08 I X..6!* *  •314 5. C, Sirk,ar and S. B. Sanyalall the fcirtors imolvecl (nuiiot be dninied lo be much less ilian 5%. The results, iiowL Ver, show tlial lliere is no lai;;c diniimitioii of the inteiisilics of the Kamau lines with the inerea^e in tlic temperature of the licpiids as observed by jn^evious utiikers in the case of some crystals and also by Anaiithakrishiian in llie case of carbon letiachloi ide. On ihe contrai}', the intensity of the Kairian lines of sniallei fi e(juem y^shift inci eases more than tlial of tlie lines of lar ’^cr frecjuency- shift with llie rise oi temperature of tlie li(jiiid as indicated Ijy relation ^1), and theiefoie the relative intensities of tluse lines undei^o changes with the changec-c- D B N S I T Voop«<u9 5I«)O c?) V-i.'^ ACK&.HOUMpF ig .of tempcratuj'c. The microphotometric records of the lines obtained in the case of lienzyl alcohol are reproduced in Fig. 1 and it can be seen that the ratio of the intensity of the line 610 to that of the line 1003 increases at the higher temperature.As regards the intensity of the Rayleigli line the results observed at tlie two teniiieratiires for the line A.|yi6 in each case are given in the tables, because, thcie is no aiipi eciablc absorption in this region. It us observed that in each case the intensity of the Rayleigh line increases with the increase of temperature. vSince the intensity of the Raman line due to C-H vibration excited by ^ 1^358 and situated close to the line A.]yi6 does not change with the increase of temperature, the ratio of the intensity of the line A4916 lo that of the Raman line mentioned above increases with the increase of temperature. This can be seen from the microphotometric records reproduced iu Fig. 2. Since there was some feeble stray light mixed with the scattered light, the observed increase isInfluence of Temperature on the Intensities of Raman Lines 3 l5Beti/vl alcohol30'C i93'CHcn/yl cliloritlo i93*C01Ter>X otoON)tn<r*X o210<r<X T'0 <01isOT)cnXK>.B/^CK GROUND^BACK'GROVU* .F k ;. 2sli^^htly less Ilian the actual increase in each case. 'Vhc increase expected tlieoretically in these cases cannot lie calculated, hecanse the values of coni- pressibility, and refractive index at the different leuiperatiires are not known.The authors are indebted to Prof. M. N. vSaha, F .R .S . for kindly allowini^ them to use the niiciophotonictei of the Palil Faboiatoiy of the Pliysics Depart­ment, University Collej^e of Science, Calcutta, and for a loan of tlic Ilil^ei two-i)risni sj»ectrograi)h used in the investigation, d'he authors are alsoindebted to the authorities of the Indian Association for the Cultivation of vScieiice for kindly providing facilities for carrying out the investigation at the laboratories of the Association.I n d i a n  A s s o c i v T i o n  i‘o k  t h i - Cia.TlVATloN 01- vSl'M-\CK2 JO, J ;o w a \ / .A K  S t u k u t , C m a 'c t t vR  E  r  E  K  E  N  C  i<: SAnanlhakrishnan, R., 1938, Effect of lemperaturc on the Ranuin spectrum of liquid rarbuntetrachloridc, Pioc. I)u1. Acad. Sii., lA, ujL.Enndsbeig, O. and Mandelstam, L., Light Si atlM'ing in cr\stals at liiglicr letnperfctu r e ,  7 . f. P h v s  , 60 , 31S4.N e y ,  M ,  J . ,  In flue nce ’ of tc m i) e r a t u r c  on the R a m a n  s p e c t r u m  of <|uarl/,, / .  / .  / ’h y s . ,C8 , 55 I< irn.stein, L. S and W e n t ,  19 3 5 ,  In l ln c n<  e of le u i i ) e ra tu r( ‘ on U jc K a m a i i  r n y s  ofe r v s t a l s ,  J  h y ^ i i a ,  2 , 503.P l a c / ( k ,  ( L ,  1 9 3 1 ,  In t e n s i t y  a n d  p c d aris n l in n  of R a m a n  s c a t te r in g  due to po lva tfj in ic  m o le c u le s ,  7 . /. lAi ys . ,  70, S pV e n k a l c s w a r l u ,  K . ,  E ffe ct  of le i i i jH ’ra tu re  on th e  i i i t i - i i s i l ie s  of R a m a n  l in e s ,  1,i ’l 'o r . f n d .  - h a d .  S c L  HA, 529.V c n k a t e s w a r l u ,  K . ,  1942, E ff e c t  of t e m p e ra tu re  on t h e  in t e n s i t ie s  of R a m a n  l in e s  f l .  Proc, Jn d .A ra d .  Sci.^ 16A ,  45.

Influence of Temperature on the Intensities of Raman Lines Due to Some Organic Liquids

http://arxiv.iacs.res.in:8080/jspui/bitstream/10821/1326/1/Influence%20of%20temperature%20on%20the%20intensities_Sirkar%20S%20C.pdf

Influence of Temperature on the Intensities of Raman Lines Due to Some Organic Liquids

Abstract

Similar works

Full text

Available Versions

IACS Institutional Repository