Studies on Ag⁻ Centers in Alkali Halides. II. Ag⁻(Na) Centers in KCl

Abstract

Optical properties of Ag⁻(Na) centers in KCl crystals were investigated. Dichroic excitation spectra for the 2.79 eV emission were observed under stimulation with polarized light at liquid nitrogen temperature. An analysis of the dichroic excitation spectra reveals that the absorption bands A₁, A₂, C₁ and C₂ arise from the transitions ¹S₀→³P₁(M=±1), ³P₁(M=0), ¹P₁(M=0) and ¹P₁(M=±1) respectively. It was also established that the upper state responsible for the 2.79 eV emission is the relaxed A₁ state. Calculations of energy levels and relative dipole strengths are given, which explain the experimental data satisfactorily. Merits and demerits of the method of excitation spectra to detect absorption bands are finally discussed.