Spectroscopic studies of excitedTm3+ions in alkaline-earth fluorides

Abstract

The vacuum-ultraviolet absorption of ${\mathrm{CaF}}_2$, ${\mathrm{SrF}}_2$, and ${\mathrm{BaF}}_2$ crystals doped with ${\mathrm{Tm}}^{3+}$ and illuminated with infrared radiation was investigated. Transitions involving the absorption of two successive photons were observed. The lifetime in the ${}_{}{}^3{}_{}{}^{}\mathrm{H}_4^{}{}_{}{}^{}$ multiplet of ${\mathrm{Tm}}^{3+}$ ions present in clusters in these hosts was investigated as a function of temperature.