ARXPS and SXPS Evidence for Surface Stabilization of Sphalerite Zn1-xFexS (110) Surfaces

Abstract

Angle resolved X-ray photoelectron spectroscopy (ARXPS) and synchrotron XPS (SXPS) have been used to study the (110) surface of two Fe containing sphalerites cleaved in vacuo. The ARXPS S 2p and Zn 2p spectra collected from a low Fe (0.02 wt.%) sphalerite revealed a low binding energy peak when collected at low take off angles (20°). These peaks have been assigned as surface core-level shifts of ~ -0.46 eV and ~ +0.34 eV, respectively. The ARXPS and SXPS S 2p spectra collected from a high Fe (14.79 wt.%) sphalerite indicated the presence of a low binding energy peak resulting from a core level shift ~ -0.42 eV below the bulk S 2p line. A higher binding energy contribution, attributed to a second surface species, was found +0.47 eV above the bulk S 2p doublet. Comparison of the S 2p spectra collected from the two sphalerites, suggested that high Fe concentrations might induce surface reconstruction in the form of surface S dimers. The surface S dimers are likely to be concentrated at high energy step edges and defects.