Cl⁻-LII,III Absorption in Solid Solutions of Alkali Chlorides

The Cl - -L II,III absorption in KCl-RbCl and KCl-NaCl solid solutions has been studied at liquid nitrogen temperature in the energy region 200-235 eV using the synchrotron orbital radiation (SOR) at INS-Tokyo. From the change of the profiles of the absorption peaks around 200 eV with the change in concentration, it is suggested that the conduction band of KCl above the \(₁\) state is similar to that of RbCl, but fairly different from that of NaCl. The spin-orbit partner of the first peak in NaCl is identified. The structure above 210 eV can be explained more reasonably by the delayed band in the core transition in solids than by the mechanism of two-electron excitation. The dependence of the position of the first peak upon concentration shows that the fluctuation of the crystal potential (randomness) in solid solutions is small in KCl-RbCl system, while large in KCl-NaCl system. In KCl-NaCl system, the randomness influences mainly conduction band rather than valence band, causing a downward bending of the \(₁\) state in conduction band with the change in concentration.