Vc. Farmer, Transverse and longitudinal crystal modes associated with OH stretching vibrations in single crystals of kaolinite and dickite, SPECT ACT A, 56(5), 2000, pp. 927-930
Citations number
7
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences
Journal title
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
Raman spectra of randomly-oriented kaolinite, dickite and nacrite show, for
coarsely crystalline material, an extra band in the OH stretching region w
hich is absent from the IR spectra of clay-size samples. Oriented single-cr
ystal Raman spectra of these minerals provide confirmation for the assignme
nt of the extra bands to transverse optical modes involving in-phase couple
d vibrations of the layer-surface hydroxyl groups. The corresponding IR ban
ds have transition moments nearly perpendicular to the layer surface, and a
ppear at the higher frequencies of the longitudinal optical modes of macros
copic crystals. (C) 2000 Elsevier Science B.V. All rights reserved.