Abstract

We have used scanning tunneling microscopy (STM), noncontact atomic force microscopy (NC-AFM), low energy electron diffraction (LEED), and ab initio calculations to study adsorbates resulting from exposure of rutile TiO 2(110)1 x 1 to methyl phosphonic acid (CH3P=O(OH) 2). At low exposures, adsorbates appear on the 5-fold coordinated Ti (Ti5c) rows. As the coverage of adsorbates approaches 0.5 ML, STM images show an ordered 2 x 1 overlayer consistent with LEED. We propose that the phosphonic acid is deprotonated with the resulting phosphonate bridging across two adjacent Ti5c atoms in the 001 direction. This bridging conformation would lead to the observed 2 x 1 overlayer and is analogous to that found for a range of carboxylates adsorbed on TiO2(110). © 2010 American Chemical Society.