Hydroxyl-Stretching Bands in Curve-Fitted Micro-Raman, Photoacoustic and Transmission Infrared Spectra of Dickite from St. Claire, Pennsylvania

S. Shoval1, S. Yariv2, K.H. Michaelian3, M. Boudeulle4 and G. Panczer4
1 Geology Group, Department of Natural Sciences, The Open University of Israel, 16 Klausner St., 61392 Tel Aviv, Israel
2 Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
3 Natural Resources Canada, CANMET Western Research Centre, Devon, Alberta, Canada T9G 1A8
4 LPCML, UMR 5620 CNRS, Claude Bernard University-Lyon 1, 43 Bd. 11 November 1918, 69622 Villeurbanne Cedex, France
E-mail of corresponding author: shoval@oumail.openu.ac.il

Abstract: The OH-stretching region in curve-fitted micro-Raman, photoacoustic and transmission IR spectra of St. Claire dickite was investigated. Polarized Raman spectra recorded from the (001) and (010) faces of the dickite crystal displayed six prominent OH bands. The relative intensities depend strongly on both the orientation of the crystallographic axes and the direction of the electric vector of the laser beam. Four out-of-plane vibrations, AA, AZ, CA and CZ, at ∼3710, 3706, 3654 and 3643 cm−1 respectively, predominate when the electric vector is perpendicular to the dickite plates. Two in-plane vibrations, DZ and DA at 3627 and 3623 cm−1, intensify when the electric vector is parallel to the plane. The relationship between band intensity and crystal orientation was interpreted in terms of longitudinal optic (LO) and transverse optic (TO) crystal vibration modes. These LO and TO crystal modes were also observed in curve-fitted photoacoustic and transmission IR spectra of coarse, non-oriented crystals of the dickite.

Key Words: Curve-fitting • Dickite • Infrared • LO and TO Crystal Modes • Micro-Raman • OH bands • SEM

Clays and Clay Minerals; August 2001 v. 49; no. 4; p. 347-354; DOI: 10.1346/CCMN.2001.0490408
© 2001, The Clay Minerals Society
Clay Minerals Society (www.clays.org)