OPTICAL SPECTROSCOPY OF NI2+ DOPED CRYSTALS OF ZN2SIO4

The polarized 15 K absorption spectra of Zn2SiO4 doped with Ni2+ consi st of three-band systems in the near-infrared (NIR) and visible (VIS) spectral regions centered at 4700, 8500, and 16500 cm(-1), respectivel y. In the tetrahedral approximation they are assigned to the d --> d t ransitions T-3(1) --> T-3(2), (3)A(2), and T-3(1)(P), respectively. Th e spectra are interpreted in terms of a T-d --> C-2v Site distortion a nd analyzed using the angular overlap model. The ligand field paramete r 10Dq is 4500 cm(-1), and the Racah parameters B and C are 780 and 36 30 cm(-1), respectively. By the inclusion of spin-orbit coupling in th e AOM calculation it is possible to assign the rich fine structure in the origin regions of the T-3(1) --> T-3(2), (3)A(2) absorptions to Ni 2+ ions occupying the two crystallographically inequivalent Zn2+ sites of Zn4SiO4. (C) 1997 Elsevier Science B.V.