Adsorption of phenylalanine on single crystal rutile TiO2(1 1 0) surface

The adsorption of the aromatic amino acid, phenylalanine on a TiO2 rutile (1 1 0) single crystal surface has been investigated with photoemission and NEXAFS (near edge X-ray absorption fine structure) spectroscopy. The results indicate initial adsorption via the carboxylate group in a bidentate configuration with the phenyl ring oriented at approximately 25° to the surface normal. The amino group remains as NH2. Subsequent layers of phenylalanine appear to adsorb as neutral molecules with H-bonding between NH2 and CO groups.