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

Abstract Two different Cr 3+ crystal-field sites in the elpasolite Cs 2 NaGaF 6 were investigated by excitation and emission spectroscopy at 4.2, 77 and 300 K. The zero-phonon lines of the 2 E → 4 A 2 transition are clearly observed on time-resolved emission spectra and associated with each type of site by high-resolution emission measurements. The different fluorescence lifetimes at 4.2 K confirm the identification of the sites. The crystal-field parameter, Dq , and Racah parameters, B and C , are determined, and we establish an intermediate crystal-field situation for both Cr 3+ centers.