Electronic Structure and Auger-Free Luminescence in Cs2ZnCl4Crystals

On the basis of the electronic structure determined from measurements of reflection and X-ray photoelectron spectra, Auger-free luminescence (AFL) of Cs 2 ZnCl 4 has been studied under the outermost-core band excitation in a temperature range of 10–300 K. A band is found at 4.8 eV, in addition to the 3.3 and 4.2 eV bands observed previously. The present study clarifies that the 4.8 eV band, as well as the 3.3 and 4.2 eV bands, originates from the Auger-free transition between the Cs 5 p outermost-core band and the Cl 3 p valence band. When the sample temperature is increased, spectral widths of the 3.3 and 4.8 eV bands become broadened, while that of the 4.2 eV band is almost kept unchanged. This suggests that the core hole created on a Cs + ion interacts with the surrounding lattice vibration. The decay profiles are found to be essentially the same for all the AFL bands. Three-peaked structure of AFL is discussed in comparison with experimental and theoretical results in CsCl.