Photoemission study of EuS/PbS electronic structure

The ultraviolet photoemission and resonant photoemission spectroscopy were used to study the electronic structure of EuS/PbS multilayers with the contribution of europium's 4f orbitals to the density of states of the valence band. The valence band photoemission spectra of galena and europium monosulfide layers show good agreement with theoretical density of state computations. The relative ratio of Eu3+ and Eu2+ ions located at the surface of EuS layer strongly depends on conditions of preparation procedures of the sample surface. For the buried EuS layer only Eu2+ ions were observed