Optical Properties and Collective Excitations in GaSe in the 2 to 80 eV Range

Optical functions of GaSc are derived from the Kramers‐Kronig analysis of reflectivity data performed at quasi‐normal incidence and at room temperature in the 2 to 80 eV range. Attempts of interpretation are suggested according to recent band structure calculations. In the experimental range, all the valence electrons are excited. On the high energy side, some structure corresponds to the excitation of 3d‐electrons of Ga and Se, respectively. The calculated position of the plasmon peak is in good agreement with energy loss experiments.