Photoconductivity of KBr Containing F Centers

The quantum efficiency or number of conduction-band electrons produced per absorbed photon in the region of the L bands at 21^∘{}K in KBr was found to be nearly unity. Photoconductivity measurements indicated that the L bands are due to electronic transitions to energy levels which are in the conduction band and that the K band is composed of two or more overlapping optical-absorption bands, of which the higher energy ones are due to electronic transitions to the conduction band. The temperature dependence of the L-band photoconductivity below 45^∘{}K can be explained by the temperature dependence of the mobility.