title: Modification of the size of supported clusters by coadsorption of an organic compound: gold and L-cysteine on rutile TiO2(110).
abstract: Using X-ray photoelectron spectroscopy we studied the coadsorption of the amino acid L-cysteine and gold on a rutile TiO(2)(110) surface under ultrahigh vacuum conditions. Irrespective of the deposition order, i.e., irrespective of whether L-cysteine or gold is deposited first, the primary interaction between L-cysteine and the gold clusters formed at the surface takes place through the deprotonated thiol group of the molecule. The deposition order, however, has a profound influence on the size of the gold clusters as well as their location on the surface. If L-cysteine is deposited first the clusters are smaller by a factor two to three compared to gold deposited onto the pristine TiO(2)(110) surface and then covered by L-cysteine. Further, in the former case the clusters cover the molecules and thus form the outermost layer of the sample. We also find that above a minimum gold cluster size the gold cluster/L-cysteine bond is stronger than the L-cysteine/surface bridging oxygen vacancy bond, which, in turn, is stronger than the gold cluster/vacancy bond.
authors.affiliation: Division of Synchrotron Radiation Research, Department of Physics, Lund University, Box 118, 221 00 Lund, Sweden.
authors.forename: Evren
authors.initials: E
authors.lastname: Ataman
authors.forename: Cristina
authors.initials: C
authors.lastname: Isvoranu
authors.forename: Jan
authors.initials: J
authors.lastname: Knudsen
authors.forename: Karina
authors.initials: K
authors.lastname: Schulte
authors.forename: Jesper N
authors.initials: JN
authors.lastname: Andersen
authors.forename: Joachim
authors.initials: J
authors.lastname: Schnadt
mesh_terms: D000327:Adsorption; D003545:Cysteine / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D056951:Photoelectron Spectroscopy; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D006046:Gold; D014025:Titanium; D003545:Cysteine