Dimerization Process in Alkanethiol Self-Assembled Monolayer on Au(111)

Abstract
Desorption kinetics of alkanethiol self-assembled monolayer (SAM) on an Au(111) surface is studied by thermal desorption spectroscopy (TDS) using a quadrupole mass spectrometer. TDS reveals for the first time that SAM desorbs to form a dimer, dialkyl disulfide molecule from the Au surface with a desorption activation energy of 32 kcal/mol. This result suggests that there exists a dimerization process of SAM molecules on the Au surface, which has been predicted by Fenter et al.. [Science 266 (1994) 1216] through diffraction studies.