physica status solidi (a) · 1992 · 13 citations · 6 references
Natural SciencesChemistryMaterials ScienceInorganic ChemistrySpectroscopic AnalysisSpectroscopyCrystal ChemistryInfrared SpectroscopyInorganic SpectroscopyOptical SpectroscopyInfrared Absorption SpectraInfrared SpectrographsTopaz Mineralogy
Natural crystals of topaz [Al(OH, F)]2SiO4, from three localities (yellow from Brazil, pink from Africa, and blue from unknown locality) are studied at RT by using the IR technique. Infrared signals arising from stretching and bending modes of OH− ions, SiO4, tetrahedra, and AI(OH, F)O4, octahedra are detected. Some peaks which according to theoretical considerations are expected to attain first-order activity, are not observed in this study either because of their low intensity or/and that they are overlapped by stronger bands.
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