The adsorption structure of glycine adsorbed on Cu(110); comparison with formate and acetate/Cu(110)

• Published in: Surface science 1998-06, Vol.407 (1-3), p.221-236
• Main Authors: HASSELSTRÖM, J, KARIS, O, WEINELT, M, WASSDAHL, N, NILSSON, A, NYBERG, M, PETTERSSON, L. G. M, SAMANT, M. G, STÖHR, J
• Format: Article
• Language: English
• Subjects: Adsorbed layers and thin films; Adsorption and desorption kinetics; evaporation and condensation; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Electron and ion emission by liquids and solids; impact phenomena; Exact sciences and technology; Photoemission and photoelectron spectra; Physics; Solid-fluid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(98)00190-3

The molecular orientation of an ordered monolayer of glycine adsorbed on Cu(110) has been studied using X-ray Photoelectron Spectroscopy (XPS), Near Edge X-ray Absorption Fine Structure (NEXAFS), X-ray Photoelectron Diffraction (XPD), Low-Energy Electron Diffraction (LEED) and theoretical calculations. In particular, the NEXAFS results are discussed in terms of the spectra of the related molecules ammonia (NH sub 3 ), formate (HCOO), and acetate (CH sub 3 COO) on Cu(110). Whereas the latter two molecules chemisorb in similar geometries, glycine is found to assume a very different chemisorption geometry. Formate and acetate bond through two equivalent oxygen atoms with the molecular plane oriented nearly perpendicular to the surface, aligned along the [110]- azimuth. In the case of adsorbed glycine (NH sub 2 CH sub 2 COO), the azimuthal orientation is still present, i.e. the bonding oxygen atoms are aligned along the [110]-azimuth, but the molecule is found to bend towards the surface. A second chemisorption bond is formed at the nitrogen end of the molecule, involving copper atoms in the neighboring [110]-row. We therefore have the interesting case of a chemisorption bond involving different functional groups in the same molecule.