The influence of non-radiative energy transfer on the excitation and decay of excited states of Er3+ in Cs2NaErCl6

Abstract

Evidence for efficient non-radiative energy transfer between erbium ions in Cs2NaErCl6 is provided by excitation and luminescence spectra and luminescence lifetimes. In one of the cross relaxation schemes the excitation of the 4F3/2 level is transferred almost exclusively to the 4F9/2 level in the 50-300 K temperature region. The process of cross relaxation which removes the excitation from the 4S3/2 level is switched thermally at about 100 K and attains high efficiency at room temperature. Experimental results are interpreted using previously reported energies of normal vibrations of ErCl63- and the crystal-field levels of Cs2NaErCl6. It has been noted that virtually all efficient energy transfer schemes in Cs2NaLnCl6 reported thus far involve transitions between multiplets of the ground terms of lanthanides. All these transitions obey the selection rules for magnetic dipole transitions.