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KSbF 6 revisited . I—A Raman and infrared study of the tetragonal phase I
Author(s) -
Heyns Anton M.,
van den Berg Magda M.
Publication year - 1995
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250260835
Subject(s) - raman spectroscopy , tetragonal crystal system , chemistry , infrared , spectral line , phase (matter) , infrared spectroscopy , crystal (programming language) , crystallography , symmetry (geometry) , crystal structure , molecular physics , analytical chemistry (journal) , optics , physics , programming language , geometry , mathematics , organic chemistry , chromatography , astronomy , computer science
The polarized Raman spectra of single crystals of KSbF 6 ‐I of P 4 2m‐D 2d 1symmetry are reported. The predicted LO‐TO splittings of the B 2 and E modes were not observed and the vibrational spectra do not indicate a non‐centrosymmetric structure. The calculated relative intensities of the Raman bands in the single‐crystal spectra agree very well with the observed values. It is shown that the anions execute fourfold reorientational motions around the S 4 axis of the crystals and an activation energy of 3.2 kcal mol −1 (13.4 kJ mol −1 ) is calculated from the variation of the linewidths of Raman bands with temperature. The barrier is penetrated by the anions and because of the jumping motions of the anions in KSbF 6 ‐I the small distortions from a centrosymmetric structure are averaged out and the Raman and infrared spectra appear to be mutually exclusive.