Investigation of emission spectra and lifetimes of Cs2NaErCl6 single crystals

The fluorescence spectra and lifetimes of low lying states of Er³⁺ in Cs₂NaErCl₆ single crystals have been investigated at room temperature and at 77 K. The assignments of the ⁴F_{$\text{9}\text{2}$}-⁴I_{$\text{15}\text{2}$} and ⁴I_{$\text{11}\text{2}$}-⁴I_{$\text{15}\text{2}$} phonon-assisted transitions have been proposed. The fluorescence lifetimes of low lying fluorescing levels have been estimated.