Spin-Orbit Splitting of \(\varGamma\) Exciton Bands in RbI and KI

Abstract

The exciton absorption bands in RbI and KI are studied by means of magnetic circular dichroism spectra, and their effective g -values are obtained. From the sign of the g eff -values, it is concluded that the lowest two sharp absorption bands, E 1 and E 2 , are (\(\varGamma^{-}_{8}\); \(\varGamma^{+}_{6}\)) and (\(\varGamma^{-}_{6}\); \(\varGamma^{+}_{6}\)) excitons, respectively, which are split by the spin-orbit interaction of iodine 5 p electrons. The higher energy bands, E 3 and E 4 , are probably the exciton bands produced by excitation of halogen 5 p electrons to the d -like conduction bands at X and L points in the Brillouin zone.