Abstracts 1997

Abstract of Publication No. 295

Thomas C. Brunold, Hans U. Güdel and Alexander A. Kaminskii
Optical spectroscopy of V4+ doped crystals of Mg2SiO4 and Ca2GeO4
Chem. Phys. Lett. 271, 327-334 (1997)      Full Text (PDF)      DOI-Link     

Abstract: Polarized low-temperature absorption spectra of V4+ doped crystals of Mg2SiO4 and Ca2GeO4 are presented and discussed. The 2E 2T2 ligand field (LF) transition peaks in the near infrared around 12000 cm1. The spectra are interpreted in terms of a stepwise Td C3v Cs symmetry reduction of VO4-4 and analyzed within the framework of the angular overlap model (AOM). The onset to the lowest energy ligand-to-metal charge-transfer transition lies in the UV above 35000 cm1. Upon photoexcitation in the visible, neither of the two systems exhibits luminescence even at cryogenic temperatures. From a comparison of the fine structure in the absorption spectra of VO44- and the isoelectronic MnO42- ion, this is shown to be due to efficient multiphonon relaxation from the 2T2 LF state.

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