ADSORPTION OF H2S ON INP(001) STUDIED BY PHOTOEMISSION SPECTROSCOPY

Adsorption of H2S on InP(001) at 140 K has been studied by valence-ban d and core-level synchrotron-radiation-induced photoemission spectrosc opy (SRPES), Peaks were found in the SRPES spectra after the H2S expos ure at E-F -6.7, -9.4, and -12.4 eV upon adsorption of H2S. They corre spond to the 2b(1), 5a(1), and 2b(2) orbitals of H2S gas, considering the intensity ratios and energy separations. This indicates that H2S a dsorbs molecularly on the surface at 140 K. We find two kinds of chemi cal state for sulfur: S2p at 162.0 and 160.8 eV for H2S strong interac tion with surface In atoms and physisorption, respectively. This is co nsistent with the changes in S2p and In4d spectra upon adsorption of H 2S. Phosphorus atoms on the surface are scarcely interacting with H2S. (C) 1997 Elsevier Science B.V.