Intensities of theR1andR2Bands in KCl Crystals

Abstract

Measurements have been made of the intensities of the ${R}_{1}$, ${R}_{2}$, $M$, and $N$ bands in KCl crystals as functions of $F$ light irradiation time. Both x-rayed and additively colored crystals were used. The x-raying and $F$ light irradiation were done at room temperature. The optical absorption measurements were made at liquid nitrogen temperature to improve the resolution of the bands. In both the x-rayed and additively colored samples the ratio of the ${R}_{2}$ and ${R}_{1}$ band intensities varied by less than a factor 1.5 when the individual intensities varied by a factor 6 or greater. No other pair of bands studied showed such a small variation in their intensity ratio.Theoretical frequencies and oscillator strengths were obtained for the $1s\ensuremath{\sigma}\ensuremath{-}2p\ensuremath{\sigma}$ and $1s\ensuremath{\sigma}\ensuremath{-}2p\ensuremath{\pi}$ transitions of ${\mathrm{H}}_{2}^{+}$ immersed in a dielectric medium and for the $1s\ensuremath{-}2p$ transition of the hydrogen atom immersed in a dielectric medium. Frequencies were also obtained for the ${^{1}\ensuremath{\Sigma}_{g}}^{+}\ensuremath{-}^{1}\ensuremath{\Pi}_{u}$ and ${^{1}\ensuremath{\Sigma}_{g}}^{+}\ensuremath{-}{^{1}\ensuremath{\Sigma}_{u}}^{+}$ transitions of ${\mathrm{H}}_{2}$ immersed in a dielectric medium. For KCl the computed frequencies of the last three transitions named have approximately the same magnitude and fall in the same order as the observed $F$, ${R}_{1}$, and ${R}_{2}$ bands, respectively. It appears possible that the observed ${R}_{1}$ and ${R}_{2}$ bands may arise from two transitions of the system of two electrons trapped at a pair of adjacent negative ion vacancies.