Pressure and photo-induced phase transitions in sulphur investigated by Raman spectroscopy

Year: 2000

Authors: Eckert B., Schumacher R., Jodl H.J., Foggi P.

Autors Affiliation: Department of Physics, University of Kaiserslautern, Erwin-Schrödinger-Straße, 67663 Kaiserslautern, Germany; Europ. Lab. for Non-Lin. Spectrosc., Largo Enrico Fermi 2, 50125 Firenze, Italy; Department of Chemistry, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy; TU Eindhoven, Schuit Institut of Catalysis, NL-5600 MB Eindhoven, Netherlands

Abstract: The phase transition of orthorhombic sulphur a-S8 to a high pressure amorphous sulphur allotrope (a-S) has been investigated by Raman spectroscopy. The conversion is found to be induced by the absorption of laser light and can be discussed in terms of ring opening followed by cis-trans conversion of the dihedral angle of S8 molecules. Laser energy and transition pressure are correlated due to the pressure tuned red shift of the absorption edge of a-S8. The amorphous (a-S) phase is observed up to 15 GPa at laser intensities below 30 µW/µm2 at 514.5 and 488.0 nm. Above this threshold power a-S transforms into a second photo-induced phase (p-S), whose discrete Raman spectrum implies an ordered molecular and crystalline structure. By further increasing pressure crystalline S6 can be created which is found to be the dominant molecular species at pressures above 10 GPa and low temperatures. A phase diagram in the range T < 300 K and p < 15 GPa is also presented. Journal/Review: HIGH PRESSURE RESEARCH

Volume: 17 (2)      Pages from: 113  to: 146

More Information: North Atlantic Treaty Organization, NATO, CRG 890814. GE*CT920046. ERBCHRXCT930105. – This work was supported by the NATO grant CRG 890814 for international collaboration in research and by the European Community under the contracts GE*CT920046 and ERBCHRXCT930105.
KeyWords: Amorphous sulphur; High pressure; Low temperature; Photo-induced sulphur; Raman spectroscopy; Sulphur S6; Sulphur S8
DOI: 10.1080/08957950008200934

ImpactFactor: 0.895
Citations: 20
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