Effect of Simultaneous Optical Bleaching and Gamma Radiation on the Room-Temperature Colorability of KCl

Abstract

The effect of simultaneous gamma irradiation and optical bleaching on ^-center production in high-purity KC1 at room temperature has been investigated. It is found that for high gamma-ray intensities (^4X10 3 R/min) simultaneous irradiation and bleaching decreases the net F-center production rate compared with that characteristic of the same samples irradiated in the dark. This suppression of F centers is associated with the later stage of coloration and is a function of bleaching intensity and dose rate. When a sample is given the same total dose and amount of bleaching sequentially, there is a small net decrease in the ^-center concentration. However, this decrease is much less than the amount of suppression observed in crystals irradiated in light. The effect of simultaneous bleaching and irradiation on the late-stage coloration suggests that the charge state of the radiation-produced vacancies, e.g., whether F centers or a. centers are formed, is very important in the coloration process. In the case of low dose rates (^92 R/min) the F-center growth curves in dark-irradiated crystals consist of essentially only early-stage centers, whereas in samples simultaneously bleached and irradiated (light-irradiated), ^-center production was completely suppressed. 611

Color Centers in MgF2

“…The second explanation 12, 16 suggests that enhanced interstitial-vacancy recombination occurs because of the increased electron-hole recombination at impurities. It is well documented that one charge state of the negative-ion vacancy is mobile at room temperature, and there is some evidence that it is the a center.…”

On the effect of irradiation intensity on defect production in pure and iodine‐doped KCl at room temperature

“…Mathews et al [18] found that a y-ray dose rate of 92 R/min resulted in F centre saturation a t 7 x 1015/cm3. I n another work [19] a y-ray dose rate of 3 x lo4 R/min produced saturation a t 3 x 101*/cm3.…”