The reaction of H2S with NiO(100) has been studied by polarization-dependen
t surface EXAFS. The results evidence reduction of the selvedge to form a N
i raft having S in four-fold sites with a S-Ni bond length of 2.21+/-0.02 A
ngstrom. The Ni-Ni in-plane distance is 2.77+/-0.09 Angstrom, representing
a 6+/-4% contraction compared to that in NiO(100). (C) 1999 Elsevier Scienc
e B.V. All rights reserved.