Rare-earth sesquisulphides investigation by ELS and XPS

The electronic structure of the rare-earth sesquisulphides gamma-Ln2S3 (Ln = La, Ce Nd, Sm, Gd, Dy) has been investigated, using ELS and XPS techniques. Particular interest was given to the electronic structure below valence band, satellite formation near Ln3d and Ln4d core levels, bulk plasmon h-omega-p and 4d --> 4f electron resonance excitations. The XPS and ELS experimental data were obtained and are summarized in two tables. Bulk plasmon energies h-omega-p in Ln2S3 were determined and it was demonstrated that all the S3p and S3s electrons contribute to the electron plasma oscillations. Some new features in the ELS spectra of Ln2S3 were revealed.