Photoelectric Hall Effect in KCl at Low Temperatures

The Hall effect for carriers released by light has been studied over a temperature range 4° to 114°K in additively colored crystals of KCl containing various concentrations of $F$ centers. A negative Hall signal was observed corresponding to electrons released from $F$ centers by light absorbed in the high-energy side of the $F$ band. The Hall mobility rises steeply below 80°K due to freezing out of the optical modes of lattice vibration. A residual mobility near 4000 ${\mathrm{cm}}^2$/volt sec is found below 30°K in the crystals prepared so far.