Adsorption Structure and Work Function of N-Acetylglycine on Cu(110) Surface

Abstract

The relation between the adsorption (conformation) structure and the work function of N-Acetylglycine (CH₃-CO-NH-CH₂COOH (AcGl)) on Cu(110) surface, has been investigated as a function of the surface temperature using reflection absorption infrared spectroscopy (IRAS), low energy electron diffraction (LEED), X-ray photoemission spectroscopy (XPS), temperature programmed desorption (TPD) and Kelvin probe. AcGl adsorbed disorderly in two dimension on Cu(110) surface. From room temperature to 350 K, ionized AcGl orients broadly perpendicular to the surface via equivalent oxygen atoms of the carboxylate group (Standing up fashion). Above 400 K, as N atom of the AcGl approaches the surface and lies, then, ionized AcGl orients parallel to the surface (Lying-down fashion) and then decompose at around 550 K. The work function increases by AcGl adsorption. The work function of the lying-down fashion is larger than the standing up fashion. It is understood that the effect of the charge transfer from the surface to molecules are more dominant than the effect of the change in the dipole moment of the conformational change of the molecule. It was experimentally clarified that the work function changed by the differences in the states of adsorption in conformation of AcGl.