Far-infrared spectra of synthetic dioctahedral micas, muscovite and tobelite

Abstract

In the 200-50 cm^-1 far-infrared region, four kinds of bands are observed: two octahedral deformation bands coupled with OH deformational vibrations between 200 and 130 cm^-1, a tetrahedral torsional band between 175 and 130 cm^-1, an interlayer I-O_inner stretching vibration and an I-O_outer stretching vibration. The weak and broad 140 cm^-1 band is K-O_inner stretching and the strong and broad 110 cm^-1 band is K-O_outer stretchings in muscovite, and the 175 cm^-1 broad band is (NH₄/ND₄)-O_inner stretching and the 140 cm^-1 broad and strong band is (NH₄/ND₄)-O_outer stretchings in tobelite.