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Etude des Spectres de Diffusion Raman Et d'Absorption Infrarouge des Cyanures de Sodium et de Potassium En Phase II et Phase III
Author(s) -
Fontaine D.
Publication year - 1980
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.1250090209
Subject(s) - chemistry , raman spectroscopy , orthorhombic crystal system , phase (matter) , potassium , sodium , analytical chemistry (journal) , nuclear magnetic resonance , crystallography , crystal structure , physics , optics , organic chemistry , chromatography
The infrared and Raman spectra of potassium and sodium cyanides have been recorded in the two orthorhombic phases (Ising spin disordered phase II and ordered phase III). By comparing the intensity of the modes we show that the two crystals have a different behaviour, though they belong to the same space group. In particular, the two librational modes in phase II are accidentally degenerate in KCN (σ ≈ 116 cm −1 at T = 150 K), while they are widely separated in NaCN (σ = 218 cm −1 and 104 cm −1 at T = 250 K). In KCN the second mode seems due to the disorder. Some possible attributions for the translatory motions in phase III are given, based on coupling with the librational motions.