Abstract
The adsorption of histidine (His) and three His-derived peptides on Au(111) has been studied by soft X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS) at the nitrogen and oxygen K edges. The peptides were elycyl histidine (Gly-H is), glycyl histidine glycine (Gly-His-Gly), and elycyl glycyl histidine (Gly-Gly-His) and were adsorbed at saturated coverage on the Au(111) surface from aqueous solution.
Coverages of I and 0.5 monolayers (ML) of His were adsorbed by evaporation in vacuum and compared with 1 ML deposited from solution. There were no significant chemical differences between the monolayers deposited in vacuum or from solution.
The Au 4f core level shift indicates that a ehemisorpti on rather than a physisorption bond is formed. In both deposited phases.
His bonds to the gold surface in anionic form via the imino nitrogen atom of the imidazole ring and the oxygen atoms or the carboxylate group.