Optical spectroscopy of V4+ doped crystals of Mg2SiO4 and Ca2GeO4
1997; Elsevier BV; Volume: 271; Issue: 4-6 Linguagem: Inglês
10.1016/s0009-2614(97)00466-1
ISSN1873-4448
AutoresThomas C. Brunold, Hans U. Güdel, Alexander A. Kaminskii,
Tópico(s)Crystal Structures and Properties
ResumoPolarized 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 cm−1. The spectra are interpreted in terms of a stepwise Td → C3v → Cs symmetry reduction of VO44− 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 cm−1. 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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