Single-crystal Raman spectroscopic study of dickite

Abstract Raman spectra were obtained from the (001), (010), and (100) faces of a St. Claire dickite specimen of known orientation. Raman spectra collected from the (010) and (100) faces of dickite are reported for the first time and reveal vibrational features significantly different from the (001) spectra. Variations in intensities of the n(OH) bands in polarized spectra were used to confirm previous band assignments, to determine the shape and orientation of the local Raman tensors for the OH1 and OH3 groups. The most striking polarization effect observed in the n(OH) region of dickite was the behavior of the a(cʹcʹ)a̅ spectrum relative to Raman and IR spectra of other orientations. Unlike previously reported spectra, the dominant feature in this spectrum was the 3643 cm-1 band. This large increase in intensity of the 3643 cm-1 band in comparison with the other n(OH) bands was related to the fact that Raman spectra were recorded from the edge faces of dickite with the electric vector of the incident laser polarized along the c axis. This permitted observation of vibrational modes polarized along the c axis. Raman frequencies of the n(OH) bands assigned to the OH2 and OH4 groups differ from their IR counterparts by 12 cm-1, suggesting that these groups may be related by a center of symmetry. For comparison, Raman spectra in the n(OH) region were also obtained from individual micro-crystals of kaolinite that were approximately 5 mm across the (001) face.

[1]  M. Tsuboi,et al.  LOCALIZED RAMAN TENSORS IN SOME BIOPOLYMERS , 1995 .

[2]  W. Bleam.  Atomic theories of phyllosilicates: Quantum chemistry, statistical mechanics, electrostatic theory, and crystal chemistry , 1993 .

[3]  V. Saunders,et al.  Periodic ab initio Hartree-Fock calculations of the low-symmetry mineral kaolinite , 1992 .

[4]  C. Johnston,et al.  Polarized Single-Crystal Fourier-Transform Infrared Microscopy of Ouray Dickite and Keokuk Kaolinite , 1990 .

[5]  C. Johnston,et al.  Influence of Hydrazine on the Vibrational Modes of Kaolinite , 1990 .

[6]  P. M. Costanzo,et al.  Ordered and Disordered Organic Intercalates of 8.4-Å, Synthetically Hydrated Kaolinite , 1990 .

[7]  D. Bish,et al.  Rietveld refinement of crystal structures using powder X-ray diffraction data , 1989 .

[8]  J. Laureyns,et al.  Polarization measurements in Raman microspectroscopy. III: Optical properties and sample orientation , 1989 .

[9]  K. Michaelian.  The Raman spectrum of kaolinite #9 at 21°C , 1986 .

[10]  G. Sposito,et al.  Raman Spectroscopic Study of Kaolinite in Aqueous Suspension , 1985 .

[11]  J. Laureyns,et al.  The Effect of High-Numerical-Aperture Objectives on Polarization Measurements in Micro-Raman Spectrometry , 1985 .

[12]  M. Lipsicas,et al.  Static and Dynamic Structure of Water in Hydrated Kaolinites. I. The Static Structure , 1984 .

[13]  F. Freund,et al.  Dehydration-related proton conductivity in kaolinite , 1981, Clay Minerals.

[14]  A. Wiewióra,et al.  The Raman spectra of kaolinite sub-group minerals and of pyrophyllite , 1979 .

[15]  P. Rouxhet,et al.  Attribution of the OH stretching bands of kaolinite , 1977, Clay Minerals.

[16]  A. Wiewióra,et al.  New Approach to the Problem of the Interlayer Bonding in Kaolinite , 1976 .

[17]  B. Swanson.  General Notation for Polarized Raman Scattering from Gases, Liquids, and Single Crystals , 1973 .

[18]  R. Ledoux,et al.  Infrared Study of Selective Deuteration of Kaolinite and Halloysite at Room Temperature , 1964, Science.

[19]  J. Fripiat,et al.  DEHYDROXYLATION OF KAOLINITE. II. CONDUCTOMETRIC MEASUREMENTS AND INFRARED SPECTROSCOPY , 1963 .

[20]  R. Roy,et al.  A new approach to assignment of infra-red absorption bands in layer-structure silicates , 1961 .