Surface XPS core-level shifts of FeS2

The XPS S 2p core-level spectra of pyrite FeS2 have been measured to study the surface core-level shifts (SCLSs). In addition to the previously found features on the low binding energy (BE) side of the line, evidence for a new structure on the high BE side is given. This feature seems to be surface sensitive. Also it is found that the final state effect may give a significant contribution to the SCLS.