title: Adsorption studies of p-aminobenzoic acid on the anatase TiO₂(101) surface.
abstract: The adsorption of p-aminobenzoic acid (pABA) on the anatase TiO2(101) surface has been investigated using synchrotron radiation photoelectron spectroscopy, near edge X-ray absorption fine structure (NEXAFS) spectroscopy, and density functional theory (DFT). Photoelectron spectroscopy indicates that the molecule is adsorbed in a bidentate mode through the carboxyl group following deprotonation. NEXAFS spectroscopy and DFT calculations of the adsorption structures indicate the ordering of a monolayer of the amino acid on the surface with the plane of the ring in an almost upright orientation. The adsorption of pABA on nanoparticulate TiO2 leads to a red shift of the optical absorption relative to bare TiO2 nanoparticles. DFT and valence band photoelectron spectroscopy suggest that the shift is attributed to the presence of the highest occupied molecular orbitals in the TiO2 band gap region and the presence of new molecularly derived states near the foot of the TiO2 conduction band.
authors.affiliation: School of Materials and The Photon Science Institute and ‡School of Physics and Astronomy, The University of Manchester , Oxford Road, Manchester M13 9PL, United Kingdom.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Thomas
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Jackman
authors.forename: Michael
authors.initials: M
authors.lastname: Wagstaffe
authors.forename: Hanna
authors.initials: H
authors.lastname: Radtke
authors.forename: Karen
authors.initials: K
authors.lastname: Syres
authors.forename: Johan
authors.initials: J
authors.lastname: Adell
authors.forename: Anna
authors.initials: A
authors.lastname: Lévy
authors.forename: Natalia
authors.initials: N
authors.lastname: Martsinovich
mesh_terms: D010129:4-Aminobenzoic Acid / Q000737:chemistry*; D000327:Adsorption; D011789:Quantum Theory; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D014025:Titanium; D010129:4-Aminobenzoic Acid