Dresden 2009 – scientific programme
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O: Fachverband Oberflächenphysik
O 27: Poster Session I (Methods: Scanning probe techniques; Methods: Atomic and electronic structure; Methods: Molecular simulations and statistical mechanics; Oxides and Insulators: Clean surfaces; Oxides and Insulators: Adsorption; Oxides and Insulators: Epitaxy and growth; Semiconductor substrates: Clean surfaces; Semiconductor substrates: Epitaxy and growth; Semiconductor substrates: Adsorption; Nano- optics of metallic and semiconducting nanostructures; Electronic structure; Methods: Electronic structure theory; Methods: other (experimental); Methods: other (theory); Solutions on surfaces; Epitaxial Graphene; Surface oder interface magnetism; Phase transitions; Time-resolved spectroscopies)
O 27.39: Poster
Tuesday, March 24, 2009, 18:30–21:00, P2
The local adsorption structure of glycine on TiO2(110) — T J Lerotholi1, W Unterberger2, E A Kröger2, M Knight1, D J Jackson1, •D Kreikemeyer Lorenzo2, K Hogan3, C Lamont3, and D P Woodruff1 — 1University of Warwick, UK — 2Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany — 3University of Huddersfield, UK
Scanned-energy mode photoelectron diffraction (PhD) is a well-known technique to determine quantitatively the local structure of adsorbates at surfaces. Here we report the application of this method to study the adsorption of glycine on TiO2(110). The adsorption of such small biologically-related molecules has potential relevance to issues of biocompatibility, and in this context TiO2 is of particular interest, since many medical implants are fabricated from Ti metal. We know from previous studies on Cu(110) that the deprotonated glycine (glycinate) bonds to the surface through both the carboxylate O atom and the amino N atom in one-fold coordinated sites. However, if the glycinate carboxylate O atoms adopt the same geometry as formate on TiO2(110), the spacing of the Ti atoms along [1-10] is much larger than the equivalent Cu-Cu spacing, and has bridging O atoms between, so a similar lying-down geometry seems unlikely. We therefore expect glycine to bond to TiO2 through either carboxylate O atoms or the amino N atoms. O1s PhD spectra show much stronger modulations than N1s PhD, consistent with bonding only through the carboxylate O atoms which occupy off-atop Ti sites, and a standing-up geometry. Quantitative evaluations of the data confirm this conclusion.