Absorption and photo-luminescence spectra of Ti³⁺ and Fe³⁺ in jadeites

Abstract

Pale green and purple jadeites have been studied by a microscope spectrophotometric method. Absorption and photoluminescence spectra of these jadeites revealed that the green and purple colors were attributed to the existence of Fe³⁺ and Ti³⁺ ions in the octahedral site, respectively. The crystal-field parameters of these ions were successfully obtained. Fe³⁺ parameters derived from five absorption bands were: Dq=1290cm⁻¹, B=566cm⁻¹, C=3470cm⁻¹. Ti³⁺ had a broad absorption band of 70nm, full width at half maximum (fwh) with a peak at 545nm and a crystal-field splitting of Dq=1840cm⁻¹. Fe³⁺ gave rise to a broad emission band (81 nm fwh) with a peak at 796nm, while Ti³⁺ did not give luminescent centers in the infrared region. These facts support that both ions occupy the octahedral site.