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Raman study of liquid sulfur
Journal of Non-Crystalline Solids 59 & 60 (1983) 1063-1066 North-Holland PublishingCompany
1063
RAMAN STUDY OF LlflUID SULFUR KATSUHIKO HATTORI and HAJIMU KAWAMURA School of Science, Kwansei Gakuin U n i v e r s i t y , I - I - 1 5 5 Ueqahara, Nishinomiya, 662, Japan The Raman spectra of l i o u i d s u l f u r un to 300°C were measured and discussed. The spectral features were apparently changed over 160°C and these were exnlained in terms o f the r a t i o between S^ rings and s u l f u r chains. The snectral feature of s u l f u r chains wer~ discussed. I. INTRODUCTION We have studied the molecular s t r u c t u r e and the v i b r a t i o n a l snectra of l i n u i d s u l f u r un to 300°C with Raman s c a t t e r i n g measurements.
We have discussed
the snectral f e a t u r e of the chain molecule which a~oears above 160°C as well as the eiaht-membered r i n a molecule ($8). of the S8 molecule I .
Ward have already discussed the spectra
Our r e s u l t f o r the S8 molecule agree with his r e s u l t .
However, his discussion on the chain molecule is r a t h e r o u a l i t a t i v e .
We have
measured the r e l a t i v e change of the S8 molecule to the chain molecule with varying temperature. ed.
The spectral s t r u c t u r e of the chain molecule was also discuss-
The r a t i o of the S8 and chain molecules has been determined bv examining
the s o l u b i l i t y
against CS2 of s u l f u r glasses auenched from various temperatures'.
The r e s u l t shows t h a t a t the melting temnerature of 120°C, s u l f u r consists of only S8 molecules, and chain molecules appear above 160°C, increasing with r a i s i n g temperature. 2. EXPERIMENTAL The 6N pure s u l f u r was sealed in an evacuated auartz tube to prevent the sample from adsorption and o x i d a t i o n .
The sample c e l l was put i n t o the tempera-
t u r e - c o n t r o l l e d heated holder and was i r r a d i a t e d with the He-Ne laser (632.8 nm) of 50 mW as the l i g h t source. The Raman snectra were obtained with 90 ° s c a t t e r i n g c o n f i g u r a t i o n with the use of Jobin Yvon HRD-2 double monochromator furnished w i t h 1800 grooves mm- I , 0.5 um blazed hologranhic q r a t i n a s .
We obtained two tvnes of n o l a r i z a t i o n
snectra: the one we c a l l the HH spectra have the c o n f i g u r a t i o n t h a t the p o l a r i zation o f both the i n c i d e n t and scattered l i q h t s are normal to the s c a t t e r i n g plane.
The o t h e r we c a l l the VH snectra have the n o l a r i z a t i o n of the i n c i d e n t
l i g h t p a r a l l e l to the s c a t t e r i n g plane, and the p o l a r i z a t i o n of the scattered l i g h t is normal to the s c a t t e r i n g plane.
0022-3093/83/0000-0000/$03.00 © 1983 North-HoUand/Physical Society of Japan
K. Hattori, H. Kawamura / Raman study of liquid sulfur
1064
3. RESULTS AND DISCUSSION The observed Raman i n t e n s i t y was m u l t i p l i e d by a f a c t o r ~ ( ~ i - w ) - 4 [ l - e x p ( - h m / k T ) ] , where ~ and ~i are the nhonon and the laser freeuency, r e s p e c t i v e l y , and T is the temperature of the specimen.
The r e s u l t a n t spectra
give the density of v i b r a t i o n a l s t a t e , i f the Raman tensor is assumed to be constant.
In f i g u r e I , the HH spectra reduced in t h i s way are shown f o r d i f f e r -
ent temperature, each of which is normalized against the height of 474 cm-I peak.
Each of these sDectra was o u i t e reproducible with temperature.
In these
spectra, 151, 218, and 248 cm-1 peaks a r e c o r r e s p o n d to t h e E2, A1, and E3 modes of bond bending v i b r a t i o n s o f S8
(bond stretchi~
=
J
AI.E2) I f.74
r i n g s , r e s p e c t i v e l y , and 434 and 474 -I cm peaks to the E3 and A1 (and a small c o n t r i b u t i o n from E2) modes of the bond s t r e t c h i n g v i b r a t i o n s of S8 r i n g s 1 ' 3 ' 4
//1 i
21ecru-1 (b°nd b'ding A1)
///J~
I
As the temperature increases above 160°C, the peaks of 151 and 218 cm-I decrease and a broad band at the bottom of these peaks reveals. On the o t h e r hand, the
r-
@
R E
¢1 m-
,,o__A~
x
o ~-X--
"o @ o-i "o o mr
o
A B m,
>m0.8
\
o 0.6 o >.,
C
o for ~/C X for B~ \
0.4 .c 0.2 lOO
2~
30o
4oo
5oo
Raman s h i f t / c m -1 FIGURE 1 The reduced Raman HH spectra of l i e u i d s u l f u r f o r various temperatures. Spectral feature above 160°C may be paid a t t e n t i o n .
~0
~6o 26o
2~o.
Tempemture~°C
FIGURE 2 Temperature dependence of the area] i n t e n s i t y r a t i o of 151 andl218 cmpeaks, against 434-474 cm- peaks. The c i r c l e and the crosslstand f o r the r a t i o of 151 and 218 cm peaks, respectively.
K. Hattori, H. Kawamura /Raman study o f liquid sulfur
1065
peak around 474 cm-I due to bond s t r e t c h i n g modes is broadened with the r i s e of temperature. Figure 2 shows the temperature dependence of the normalized areal i n t e n s i t y r a t i o of 151 and 218 cm-I l i n e s , against 434-474 cm-I l i n e s .
In the fi~Hre,
the c i r c l e and cross stand f o r the r a t i o of 151 and 218 cm-I l i n e s , r e s p e c t i v e l y Both of these s i m i l a r l y decrease with r a i s i n g temperature above 160°C, and these curves agree with t h a t of the r a t i o of S8 rings to the t o t a l s u l f u r molecules derived from the s o l u b i l i t y -I
against CS22. This f a c t shows t h a t the 151 and 218 -I
cm
l i n e s are due to the S8 ring and the broad l i n e around 434-474 cm
.
is
associated with both the ring and chain molecules. In order to separate the modes in the spectra, we used the p o l a r i z a t i o n spectra.
I f IHH(~) and IVH(m) are the spectral i n t e n s i t y of HH and VH p o l a r i zations, the s u b t r a c t i o n IHH(~)-(4/3)IvH(m) gives the spectrum of t o t a l l y symmetric A1 mode5.
Liquid sulfur, (HH-VH) spectro
Figure 3 shows t h i s (HH-VH) spectra. I t is also shown t h a t the l i n e of the -I bond s t r e t c h i n g A1 mode at 474 cm become broader and asymmetric at higher temperature.
"i
ZSO
From f i g u r e 2 i t can be
__~
C E 01::
0 --
0
(HH-VH)spectra
o
"0
~0
160
"0
/. /
150 f
/ 130
~
~.~_____ 0
120~ ~oo
/
200
36o Raman
4bo
shift/cm
S
5OO
-1
FIGURE 3 The reduced Raman (HH-VH) spectra o f l i q u i d s u l f u r obtained at the temperatures i n d i c a t e d . The shoulder ~n the lower s h i f t side of the 474 cm- peak is enhanced above 160°C.
, o-.~- - -o
120
160
200 250 Temperature/'C
FIGURE 4 Temperature dependence of the areal i n t e n s i t y r a t i o of the stretched should e r l P a r t against the whole peak of 474 cm- . The curving feature above 160°C shows the increase of the polymeric s u l f u r chain.
K. Hattori, H. Kawamura / Raman study of liquid sulfur
1066
seen t h a t a t the highest temoerature of 300°C, the c o n t r i b u t i o n from the r i n g molecule to t h i s l i n e is about 20%. Since the l i n e shade of the ring molecule is symmetric, the shoulder Dart of the l i n e w i l l cule.
onlv come from the chain mole-
So t h a t the area of the shoulder Dart of the l i n e r e f l e c t s a constant
f r a c t i o n of the t o t a l area of snectral l i n e due to the chain molecule. In f i g u r e 4, the areal i n t e n s i t y r a t i o of the shoulder n a r t against the whole l i n e is p l o t t e d as a function of temnerature.
The curve shows the increase of
the polymeric chain molecule above 16N°C, showing the onnosite tendency with the curve in f i g u r e 2. I t is i n t e r e s t i n g t h a t the snectrum f o r bond bending v i b r a t i o n s of the chain molecule is smeared out at the bottom of the bond bending sDectral l i n e of the ring molecule, while f o r the bond s t r e t c h i n g mode of the chain molecule is sufficiently
narrow to be c l e a r l y observed.
This d i f f e r e n c e may be exolained
in the f o l l o w i n g way: since the bond angle of the s u l f u r atom is 107°54 ' , the s t r e t c h i n g v i b r a t i o n of each bond is nearly decounled.
So the snectral band
f o r bond s t r e t c h i n g modes of nolvmeric chains may be narrow.
On the other hand,
f o r bond bending modes, many v i b r a t i o n s counle each o t h e r , g i v i n g r i s e to the broad band. In conclusion, from Raman snectra, i t has been observed t h a t at the melting temnerature of 12N°C, the l i n u i d s u l f u r contains only S8 ring molecules, and above 160°C, nolymeric chain molecules increase un to 80f at 3nO°C.
I t is also
suggested t h a t f o r the chain molecule, the snectral band of bond s t r e t c h i n g modes is r e l a t i v e l y
narrow, w h i l e t h a t of bond bending modes is very broad.
REFERENCES I ) A.T. Ward, J. Phys. Chem. 72 (1968) 4133. 2) D.L. Hammick et a l . J. Chem. Soc. (1929) 797. 3) D.W. Scott et a l . J. Mol. Spectrosc. 13 (1964) 313. 4) G. Lucovsky et a l . Sol. State Commun. 5 (1967) 113. 5) ~. Placzek, Handbuch der Radiologie, v o l . 6, Dart 2 (Akademische Verlagsgeselschaft, L e i p z i g , 1934).
1063
RAMAN STUDY OF LlflUID SULFUR KATSUHIKO HATTORI and HAJIMU KAWAMURA School of Science, Kwansei Gakuin U n i v e r s i t y , I - I - 1 5 5 Ueqahara, Nishinomiya, 662, Japan The Raman spectra of l i o u i d s u l f u r un to 300°C were measured and discussed. The spectral features were apparently changed over 160°C and these were exnlained in terms o f the r a t i o between S^ rings and s u l f u r chains. The snectral feature of s u l f u r chains wer~ discussed. I. INTRODUCTION We have studied the molecular s t r u c t u r e and the v i b r a t i o n a l snectra of l i n u i d s u l f u r un to 300°C with Raman s c a t t e r i n g measurements.
We have discussed
the snectral f e a t u r e of the chain molecule which a~oears above 160°C as well as the eiaht-membered r i n a molecule ($8). of the S8 molecule I .
Ward have already discussed the spectra
Our r e s u l t f o r the S8 molecule agree with his r e s u l t .
However, his discussion on the chain molecule is r a t h e r o u a l i t a t i v e .
We have
measured the r e l a t i v e change of the S8 molecule to the chain molecule with varying temperature. ed.
The spectral s t r u c t u r e of the chain molecule was also discuss-
The r a t i o of the S8 and chain molecules has been determined bv examining
the s o l u b i l i t y
against CS2 of s u l f u r glasses auenched from various temperatures'.
The r e s u l t shows t h a t a t the melting temnerature of 120°C, s u l f u r consists of only S8 molecules, and chain molecules appear above 160°C, increasing with r a i s i n g temperature. 2. EXPERIMENTAL The 6N pure s u l f u r was sealed in an evacuated auartz tube to prevent the sample from adsorption and o x i d a t i o n .
The sample c e l l was put i n t o the tempera-
t u r e - c o n t r o l l e d heated holder and was i r r a d i a t e d with the He-Ne laser (632.8 nm) of 50 mW as the l i g h t source. The Raman snectra were obtained with 90 ° s c a t t e r i n g c o n f i g u r a t i o n with the use of Jobin Yvon HRD-2 double monochromator furnished w i t h 1800 grooves mm- I , 0.5 um blazed hologranhic q r a t i n a s .
We obtained two tvnes of n o l a r i z a t i o n
snectra: the one we c a l l the HH spectra have the c o n f i g u r a t i o n t h a t the p o l a r i zation o f both the i n c i d e n t and scattered l i q h t s are normal to the s c a t t e r i n g plane.
The o t h e r we c a l l the VH snectra have the n o l a r i z a t i o n of the i n c i d e n t
l i g h t p a r a l l e l to the s c a t t e r i n g plane, and the p o l a r i z a t i o n of the scattered l i g h t is normal to the s c a t t e r i n g plane.
0022-3093/83/0000-0000/$03.00 © 1983 North-HoUand/Physical Society of Japan
K. Hattori, H. Kawamura / Raman study of liquid sulfur
1064
3. RESULTS AND DISCUSSION The observed Raman i n t e n s i t y was m u l t i p l i e d by a f a c t o r ~ ( ~ i - w ) - 4 [ l - e x p ( - h m / k T ) ] , where ~ and ~i are the nhonon and the laser freeuency, r e s p e c t i v e l y , and T is the temperature of the specimen.
The r e s u l t a n t spectra
give the density of v i b r a t i o n a l s t a t e , i f the Raman tensor is assumed to be constant.
In f i g u r e I , the HH spectra reduced in t h i s way are shown f o r d i f f e r -
ent temperature, each of which is normalized against the height of 474 cm-I peak.
Each of these sDectra was o u i t e reproducible with temperature.
In these
spectra, 151, 218, and 248 cm-1 peaks a r e c o r r e s p o n d to t h e E2, A1, and E3 modes of bond bending v i b r a t i o n s o f S8
(bond stretchi~
=
J
AI.E2) I f.74
r i n g s , r e s p e c t i v e l y , and 434 and 474 -I cm peaks to the E3 and A1 (and a small c o n t r i b u t i o n from E2) modes of the bond s t r e t c h i n g v i b r a t i o n s of S8 r i n g s 1 ' 3 ' 4
//1 i
21ecru-1 (b°nd b'ding A1)
///J~
I
As the temperature increases above 160°C, the peaks of 151 and 218 cm-I decrease and a broad band at the bottom of these peaks reveals. On the o t h e r hand, the
r-
@
R E
¢1 m-
,,o__A~
x
o ~-X--
"o @ o-i "o o mr
o
A B m,
>m0.8
\
o 0.6 o >.,
C
o for ~/C X for B~ \
0.4 .c 0.2 lOO
2~
30o
4oo
5oo
Raman s h i f t / c m -1 FIGURE 1 The reduced Raman HH spectra of l i e u i d s u l f u r f o r various temperatures. Spectral feature above 160°C may be paid a t t e n t i o n .
~0
~6o 26o
2~o.
Tempemture~°C
FIGURE 2 Temperature dependence of the area] i n t e n s i t y r a t i o of 151 andl218 cmpeaks, against 434-474 cm- peaks. The c i r c l e and the crosslstand f o r the r a t i o of 151 and 218 cm peaks, respectively.
K. Hattori, H. Kawamura /Raman study o f liquid sulfur
1065
peak around 474 cm-I due to bond s t r e t c h i n g modes is broadened with the r i s e of temperature. Figure 2 shows the temperature dependence of the normalized areal i n t e n s i t y r a t i o of 151 and 218 cm-I l i n e s , against 434-474 cm-I l i n e s .
In the fi~Hre,
the c i r c l e and cross stand f o r the r a t i o of 151 and 218 cm-I l i n e s , r e s p e c t i v e l y Both of these s i m i l a r l y decrease with r a i s i n g temperature above 160°C, and these curves agree with t h a t of the r a t i o of S8 rings to the t o t a l s u l f u r molecules derived from the s o l u b i l i t y -I
against CS22. This f a c t shows t h a t the 151 and 218 -I
cm
l i n e s are due to the S8 ring and the broad l i n e around 434-474 cm
.
is
associated with both the ring and chain molecules. In order to separate the modes in the spectra, we used the p o l a r i z a t i o n spectra.
I f IHH(~) and IVH(m) are the spectral i n t e n s i t y of HH and VH p o l a r i zations, the s u b t r a c t i o n IHH(~)-(4/3)IvH(m) gives the spectrum of t o t a l l y symmetric A1 mode5.
Liquid sulfur, (HH-VH) spectro
Figure 3 shows t h i s (HH-VH) spectra. I t is also shown t h a t the l i n e of the -I bond s t r e t c h i n g A1 mode at 474 cm become broader and asymmetric at higher temperature.
"i
ZSO
From f i g u r e 2 i t can be
__~
C E 01::
0 --
0
(HH-VH)spectra
o
"0
~0
160
"0
/. /
150 f
/ 130
~
~.~_____ 0
120~ ~oo
/
200
36o Raman
4bo
shift/cm
S
5OO
-1
FIGURE 3 The reduced Raman (HH-VH) spectra o f l i q u i d s u l f u r obtained at the temperatures i n d i c a t e d . The shoulder ~n the lower s h i f t side of the 474 cm- peak is enhanced above 160°C.
, o-.~- - -o
120
160
200 250 Temperature/'C
FIGURE 4 Temperature dependence of the areal i n t e n s i t y r a t i o of the stretched should e r l P a r t against the whole peak of 474 cm- . The curving feature above 160°C shows the increase of the polymeric s u l f u r chain.
K. Hattori, H. Kawamura / Raman study of liquid sulfur
1066
seen t h a t a t the highest temoerature of 300°C, the c o n t r i b u t i o n from the r i n g molecule to t h i s l i n e is about 20%. Since the l i n e shade of the ring molecule is symmetric, the shoulder Dart of the l i n e w i l l cule.
onlv come from the chain mole-
So t h a t the area of the shoulder Dart of the l i n e r e f l e c t s a constant
f r a c t i o n of the t o t a l area of snectral l i n e due to the chain molecule. In f i g u r e 4, the areal i n t e n s i t y r a t i o of the shoulder n a r t against the whole l i n e is p l o t t e d as a function of temnerature.
The curve shows the increase of
the polymeric chain molecule above 16N°C, showing the onnosite tendency with the curve in f i g u r e 2. I t is i n t e r e s t i n g t h a t the snectrum f o r bond bending v i b r a t i o n s of the chain molecule is smeared out at the bottom of the bond bending sDectral l i n e of the ring molecule, while f o r the bond s t r e t c h i n g mode of the chain molecule is sufficiently
narrow to be c l e a r l y observed.
This d i f f e r e n c e may be exolained
in the f o l l o w i n g way: since the bond angle of the s u l f u r atom is 107°54 ' , the s t r e t c h i n g v i b r a t i o n of each bond is nearly decounled.
So the snectral band
f o r bond s t r e t c h i n g modes of nolvmeric chains may be narrow.
On the other hand,
f o r bond bending modes, many v i b r a t i o n s counle each o t h e r , g i v i n g r i s e to the broad band. In conclusion, from Raman snectra, i t has been observed t h a t at the melting temnerature of 12N°C, the l i n u i d s u l f u r contains only S8 ring molecules, and above 160°C, nolymeric chain molecules increase un to 80f at 3nO°C.
I t is also
suggested t h a t f o r the chain molecule, the snectral band of bond s t r e t c h i n g modes is r e l a t i v e l y
narrow, w h i l e t h a t of bond bending modes is very broad.
REFERENCES I ) A.T. Ward, J. Phys. Chem. 72 (1968) 4133. 2) D.L. Hammick et a l . J. Chem. Soc. (1929) 797. 3) D.W. Scott et a l . J. Mol. Spectrosc. 13 (1964) 313. 4) G. Lucovsky et a l . Sol. State Commun. 5 (1967) 113. 5) ~. Placzek, Handbuch der Radiologie, v o l . 6, Dart 2 (Akademische Verlagsgeselschaft, L e i p z i g , 1934).