Formation and Surface Structure of Dialkyl Diselenide(DADSe) SAMs on Au(111)

Abstract

Surface structure and property of dialkyl diselenide (DADSe) self-assembled monolayers (SAMs) formed on Au(111) were investigated by scanning tunneling microscopy (STM), cyclic voltammetry (CV), contact angle measurements, thermal desorption spectroscopy (TDS) and X-ray photoelectron spectroscopy (XPS). Compared to the formation of well ordered SAMs on Au(111) by alkanethiols or dialkyl disulfides, DADSe SAMs are composed of disordered phase and a number of vacancy island (VIs) with a higer VIs fraction. XPS study revealed that DADSe SAMs were formed by chemical bond via Se-Au(111) form the presence of XPS peak at 160 eV. In addition, from TDS and STM studies, we found that desorption behavior and annealing effect of DADSe SAMs as a function of surface temperature are completely different form those of alkanethiol SAMs due to different binding condition. We also found that DADSe SAMs were formed unique VIs with a straight-line shape after annealing at elevated temperature.