A grazing incidence surface X-ray absorption fine structure (GIXAFS) studyof alkanethiols adsorbed on Au, Ag, and Cu

Self-assembled monolayers of n-alkanethiols, CH3-(CH2)(x)-SH, on An, Ag, an d Cu have been studied with GIXAFS at the sulfur K-edge. For both pentaneth iol and decanethiol monolayers on Ag and Cu, the three-fold hollow site is found to be the most probable sulfur binding site. However, observations fo r octadecanethiol indicate that the three-fold hollow site is not the exclu sive binding site. In addition, the possible existence of disulfide bonds o n the metal surface (adsorbed dialkyldisulfides) is not supported by the da ta. Preliminary results from monolayers on An are also reported. (C) 2000 E lsevier Science B.V. All rights reserved.