Color Centers and Trapped Charge in KCl and KBr

Abstract

Potassium chloride and bromide crystals have been irradiated with x-rays at -183\ifmmode^\circ\else\textdegree\fi{}C and the behavior of the ${V}_{1}$, $F$, and ${F}^{\ensuremath{'}}$ optical absorption bands observed during subsequent warming to room temperature. The thermal bleaching of the ${V}_{1}$-band is accompanied by a decrease in the $F$-band, the appearance of free charge within the crystal, and luminescence. The data indicate that positive holes are released from traps during this process.