Raman Studies of Sulfur Crystal (α-S₈) at High Pressures and Low Temperatures

Abstract

We have studied the temperature and pressure dependence of the vibrational energy levels of orthorhombic sulfur. Spectroscopic measurements were performed using standard Raman equipment; high pressure experiments made use of a diamond anvil cell (DAC). In general all external modes are sensitive to temperature variation in the range 50−300 K; internal modes exhibit a different behavior. It was found that mode energies were more influenced by pressure (0−5 GPa) than by temperature (12−300 K). In addition it was found that the intensities of prominent features of the Raman spectrum were pressure dependent.

How the vibrational frequency varies with temperature

“…Figure shows temperature dependence of mode at 86 cm −1 in crystalline α‐S 8 . The low‐wavenumber vibrations in α‐S 8 (<200 cm −1 ) are dominated by van der Waals intermolecular interaction . The ω( T ) function was fitted by the thermal population of ω itself only.…”

Investigating Multiscale Spatial Distribution of Sulfur in a CNT Scaffold and Its Impact on Li–S Cell Performance

“…The fundamental excitations centered at 159, 222, and 475 cm –1 indicate the presence of the S8 on 5.8 mg/cm 2 S-CNT . These three peaks respectively represent antisymmetric S–S bending mode (antiδ S–S ), symmetric S–S bending mode (symδ S–S ), and symmetric S–S stretching mode (symν S–S ) . The characteristic Raman peaks centered at 1349, 1592, and 2683 cm –1 ascribe to carbon D-band, G-band, and 2D-band, respectively .…”

“…These clusters have noticeably different peak ratios ( I b / I s ) between the symmetric S–S bending mode (symδ S–S at 222 cm –1 ) and the symmetric S–S stretching mode (symν S–S at 475 cm –1 ). As noted by Foggi et al, the symδ S–S mode characterizes the unstrained S8 rings, whereas the symν S–S preferably stands for the intramolecular vibration. A flattened S8 ring has a suppressed symδ S–S bending mode, hence a smaller I b / I s value.…”

“…29 These three peaks respectively represent antisymmetric S−S bending mode (antiδ S−S ), symmetric S−S bending mode (symδ S−S ), and symmetric S−S stretching mode (symν S−S ). 30 The characteristic Raman peaks centered at 1349, 1592, and 2683 cm −1 ascribe to carbon D-band, G-band, and 2D-band, respectively. 31 Mapping scaled by the intensity of an individual Raman allows for estimating the distribution of the representative species.…”

Dynamics of pH on the oxidation of HS- with iron(III) chelates in anoxic conditions

“…The most stable form of elemental sulfur has an orthorhombic structure (Meyer, 1976;Tebbe et al, 1982;Eckert et al, 1996) precipitating as whitish colloids ( -S 8 ) due to low aqueous solubility (5 g/L at 293 K, Boulegue, 1978). The cyclic S 8 comes from polysulfide precursors formed during H 2 S oxidation in iron(III) chelate solutions (Clarke et al, 1994;Steudel, 1996, Kleinjan et al, 2005a.…”