Optical Absorption Spectra of the Alkali Halides at 10°K

Abstract

The absorption spectra of all the alkali halides except LiF and LiI, measured in the range 5.0 to 12.0 eV at 10\ifmmode^\circ\else\textdegree\fi{}K, are presented. These data complement earlier measurements made at 80\ifmmode^\circ\else\textdegree\fi{}K. Identification of excition lines involving $d$-like electrons is made by a comparison of the crystal absorption and the absorption spectra of rare-gas atoms. From the positions of exciton states with $d$-like electrons, the energy of the second conduction band at $\ensuremath{\Gamma}$ is deduced for some of the alkali halides. The results of these deductions are compared with recent calculations of the conduction-band structure of KI and KCl.