Characterization and Assignment of Far Infrared Absorption Bands of K+ in Muscovite

M. Diaz1, V.C. Farmer2 and R. Prost1
1 Unité de Science du Sol, INRA, Route de Saint Cyr, 78026 Versailles, cedex, France
2 Soil Science Group, Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB15 8QH, UK
E-mail of corresponding author: prost@versailles.inra.fr

Abstract: To assign far infrared (FIR) absorption bands of K+ in muscovite, dichroic experiments were performed. For a muscovite crystal rotated about a crystallographic axis, c*, a, or b, two bands corresponding to vibration modes of K+ appear, respectively, at 107 and 110 cm−1 (rotation about c*), 107 and 143 cm−1 (rotation about a), and 110 and 143 cm−1 (rotation about b). Two in-plane modes at 107 and 110 cm−1 and one out-of-plane mode at 143 cm−1 are identified for the vibrations of K+ in muscovite. Each of these transition moments are near the crystallographic axes b, a, and c, respectively. These observations match well predictions based on the approximate C3i symmetric environment of K+, although the site symmetry in the space group of muscovite is only C2.

Key Words: Dichroism • Far Infrared • Muscovite • Potassium • Transition Moment • Vibration Mode

Clays and Clay Minerals; August 2000 v. 48; no. 4; p. 433-438; DOI: 10.1346/CCMN.2000.0480403
© 2000, The Clay Minerals Society
Clay Minerals Society (www.clays.org)