Infrared luminescence properties of Ni 2+ in various chloride lattices: CsCdCl 3, CsMgCl 3, CdCl 2, and MgCl 2

Abstract

A study of the infrared luminescence of Ni 2+ ( 3A 2g« 3T 2g: O h notation) in four structurally related compounds is presented. Low temperature IR luminescence spectra are presented for the title compounds; energy assignments are given for the fine structure observed in the spectrum of Ni 2+:MgCl 2. Low temperature 3A 2gå 3T 2g absorption spectra for Ni 2+:CsCdCl 3 and Ni 2+:MgCl 2 are shown; fine structure is observed mainly on the high-energy side of these bands. Temperature dependences of luminescence intensities and of luminescence decay rates are given; these dependences are described in terms of radiative and non-radiative models. Non-radiative decay is assumed to be through multi-phonon emission, and we use a single configuration coordinate (SCC) model. For each compound, the ‘effective’ phonon frequency of non-radiative decay is estimated to be approximately the mean frequency of the phonon spectrum. Variation in non-radiative behavior is well described in terms of the variation of the number of phonons involved and the Huang-Rhys parameter.