SURFACE STURUCTURE AND PHASE TRANSITION OF DIOCTYLDISELENIDE SELF-ASSEMBLED MONOLAYERS ON AU(111)

Abstract

Surface structure and phase transition of Dioctyl diselenide (DODSe) Self-assembled monolayers (SAMs) on Au(111) were investigated by scanning tunneling microscopy (STM), cyclic voltammetry (CV) and contact angle measurement. Compare to the formation of well ordered octanethiol SAMs on Au(111), DODSe SAMs are composed of disordered phase and a number of vacancy island (VIs) with a higher VIs fraction. By varying the DODSe solution immersing time and solution concentration, we could observed phase transition of DODSe (from surface aggregation phase step to missing low structure step, from missing low structure step to disordered dense phase step). Also in different DODSe solution concentration, from VIs fraction of DODSe SAM is increased as concentration increases. It is not common in thiol- head group SAMs system. We also found that DODSe SAMs were formed unique VIs with a straight-line shape after annealing at elevated temperature, which are never reported in other SAMs system.