Polarized Singlet and Triplet Luminescence and Off-Centre Position of Excited In+ Ions in a CsBr :In Crystal

Spectral and polarization characteristics as well as the decay kinetics of the CsBr : In luminescence are investigated in the temperature range from 1.75 to 300 K. Four emission bands (at 2.44, 2.75, 3.27 and 3.32 eV) are observed at low temperatures and interpreted correspondingly as AT, Ax, B, and C emission of In+ centres. The symmetry of the Jahn‐Teller minima of the triplet relaxed excited state (RES) responsible for the Ax and the B emission is established to be trigonal and rhombic, respectively. The AT and the C emission is caused by the radiative decay of the tetragonal Jahn‐Teller minima of the triplet (A) and the singlet (C) excited state. Two slow components are found in the decay kinetics of both, the AT and the Ax emission at T ⪅ 3 K. It points to the splitting of the metastable level both, in the tetragonal (T) minima and in the trigonal (X) minima of the triplet RES. It is shown that the effects observed are caused by an off‐centre displacement of the In+ ion in the triplet RES from a crystal lattice site. For excited ns2 ions in CsCl‐type hosts these effects are not observed before. This is the first observation of the off‐centre effects in the trigonal minima of the triplet RES of ns2 ions. [Russian Text Ignored.]