The interface electronic structure of thiol terminated molecules on cobalt and gold surfaces

The bonding strength and interfacial electronic properties of biphenyldimethyldithiol (HS–CH2–C6H4– C6H4–CH2–SH) adsorbed on Au(111) and polycrystalline cobalt are identified from combined photoemission and inverse photoemission. In order to develop a better understanding of the thiol functional group to metal surface interaction, the stable orientation, bonding site, bonding strength and interfacial electronic properties of methylthiol (S–CH3) adsorbed on Au(111) and Co(0001) have been determined by ab initio density functional calculations. Both experiment and theory suggest that thiol bonding to cobalt surfaces is stronger compared to gold surfaces. The transfer of charge toward the adsorbed sulfur is greater for the thiols on cobalt than on gold.