Study of optical properties of Cr3+ ions in Cs2NaAlF6 single crystals

Abstract Emission and excitation spectra for Cs 2 NaAlF 6 :Cr 3+ are presented. The near-infrared fluorescence observed at 77 and 4.2 K are attributed to the zero-phonon spin-forbidden transition 2 E ( 2 G )→ 4 A 2 ( 4 F ) while at room-temperature the emission is assigned to the 2 T 2 ( 2 F )→ 4 A 2 ( 4 F ) transition. Two non-equivalent octahedral sites are identified through time-resolved measurements and lifetime fluorescence bands are measured. The Racah and crystal-field parameters are calculated for both sites.