Site Specific Surface Interaction of Electron Donors and Acceptors on FeS₂(100) Cleavage Planes

Abstract

Abstract The interaction of UHV cleaved FeS 2 (100) surfaces with adsorbed H 2 O as an electron donor and adsorbed Br 2 as an electron acceptor has been studied with LEED, LEISS, UPS, and XPS to simulate semiconductor/electrolyte interfaces in UHV. The (100) cleavage plane is characterized by a c(2 × 2) or p(√2 × 2)R 45° LEED pattern which is interpreted in terms of the unreconstructed FeS 2 surface. H 2 O is molecularly adsorbed at low temperatures (100 K) and desorbs completely at room temperature (RT). LEIS‐spectra taken at low coverages (<0.5 ML) suggest a preferential interaction with the Fe sites. Br 2 is ionosorbed at low coverages (<0.5 ML) as well interacting specifically with Fe‐sites. It is molecularly adsorbed at higher coverages. The ionosorbed part does not desorb at RT. The behavior of specific adsorption is related to the electronic nature of the band edges which are derived from Fe d‐states.