Intensities of theR1andR2Bands in KCl Crystals

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.