The FS+ Center in KCl Crystals’) Part I: Formation and Bleaching Kinetics BY

A quantitative analysis of the higher transitions of the M center in the UV up to 5.0 eV in KC1 crystals with high [MI: [F] ratio and unaligned and aligned M centers shows several new excitations (“LM bands”). Assuming that the LM excitation leads to conductive states, a simple electron kinetic model shows that UV irradiation of the F + M center system produces ionized F and M centers (a and Fi) while competing capture processes partially destroyed them or form F and M centers. The F; center production spectrum should closely follow the absorption ratio of LM:LF while the bleaching spectrum should follow the F ’ and M spectrum. Experimental confirmation of this model is presented. By X-raying the crystal (containing F + M centers) at LHeT, extra electron traps are introduced into the crystal and shift the equilibrium of the reaction to higher amount of I?; center, which are not stabilized by F ’ and M centers. These extra F; centers anneal out near 40’K in parallelity with the third stage annealing of X-ray produced a-centers-interstititala anions. L’analyse quantitative des transitions optiques du centre M dans I’dtraviolet jusqu ’ A 5 eV dens des cristaux de KC1 ayant un rapport de concentration [M]:[F] BevB et des centres M non alignb ou alignb montre la p r h n c e de plusieurs nouvelles bandes d’absorp