Mössbauer Studies in Uncolored and ColoredCo57Diffused Single Crystals of KCl and NaCl

Mössbauer spectra of uncolored, additively colored, and x-irradiatively colored KCl and NaCl single crystals diffused with ${\mathrm{Co}}^{57}$ are reported. Evidence of electron trapping effects by iron impurity ions was observed. It was also observed that the degree of ionicity and the mean-square amplitude of impurity-ion vibrations changed after additive coloration. The changes resulting from x-irradiation and the effect of optical bleaching are discussed. Efforts to find the site (interstitial or substitutional) for the ${\mathrm{Fe}}^{57}$ impurity ions in KCl as well as in NaCl were also made.