Investigation of Cr3+ ions in Cs2NaGaF6 single crystals by optical spectroscopy

Two different Cr3+ crystal-field sites in the elpasolite Cs2NaGaF6 were inv estigated by excitation and emission spectroscopy at 4.2, 77 and 300 K. The zero-phonon lines of the E-2 --> (4)A(2) transition are clearly observed o n time-resolved emission spectra and associated with each type of site by h igh-resolution emission measurements. The different fluorescence lifetimes at 4.2 K confirm the identification of the sites. The crystal-field paramet er, Dq, and Racah parameters, B and C, are determined, and we establish an intermediate crystal-field situation for both Cr3+ centers. (C) 1999 Elsevi er Science Ltd. All rights reserved.