Gitterschwingungsspektren

Abstract

Force constants and normal coordinates of MnS2 , FeS2 , RuS2, RuSe2, RuTe2, OsS2 and PtP2 are calculated based on the five ir active vibrations of the pyrite lattice. By setting up a valence force field consisting of short and long range M -X, X2 -X2 and M -M stretching constants it has proved possible to obtain good agreement between experimental and calculated frequencies with expection of FeS2 and RuS2 . The force constants corresponding to the shortest metal chalcogen distances (MnS2: 0.30, RuSe,: 0.88, RuTe2: 0.62, OsS2: 1.32, PtP2: 1.22 mdyn/A) are mainly responsible for the ir frequencies. For RuSe2 and RuTe, the forces between adjacent X2 groups are not negligible. Whereas the force constants of OsS2 and PtP2 are of comparable strength, the forces in MnS2 are significantly weaker than those in the other compounds. The normal coordinates of MnS2, OsS2 and PtP2 , and RuSe2 and RuTe2 show significant differences according to both the contribution of the 6 symmetry coordinates to the 5 ir active vibrations and the assignment of the spectra.

Electronic structure, optical and X‐ray emission spectra in FeS2

“…Most reliable values are reported from photoconductivity measurements yielding values of approximately 0.9 eV to 0.95 eV. Data on the lattice structure and dynamics are available from ultrasonic measurements [19], shock wave compression [20], and Raman and infrared spectroscopy [21][22][23][24].…”