Color Centers in KC1 ContainingLi+orNa+

A new absorption band has been discovered in KC1 crystals containing ${\mathrm{Li}}^{+}$ or ${\mathrm{Na}}^{+}$ ions. The conditions for formation of this band and its behavior during thermal or optical bleaching indicate that it is due to a center similar to the $B$ center of crystals containing ${\mathrm{Ag}}^{+}$. The model of the $B$ center proposed by Etzel and Schulman is assumed and a mechanism for its formation is proposed.