Differential reflectivity and angle-resolved photoemission of PbS(1 0 0)

The surface electronic structure of a PbS sample, cleaved in ultra-high-vacuum environment, has been studied with surface differential reflectivity (SDR) and angle-resolved photoelectron spectroscopy (ARUPS). The ARUPS spectra show the presence of two surface (resonance) states along the two angular directions [0 0 1] and [0 1 1]. SDR shows the existence of a gap of approximately 2.1 eV and two more optical transitions at energies of 2.7 and 3.1 eV. These transitions have been, tentatively, assigned to different points in the surface Brillouin zone. © 2001 Elsevier Science B.V.