These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Adsorption states and mobility of trimethylacetic acid molecules on reduced TiO(2)(110) surface.
    Author: Lyubinetsky I, Deskins NA, Du Y, Vestergaard EK, Kim DJ, Dupuis M.
    Journal: Phys Chem Chem Phys; 2010 Jun 21; 12(23):5986-92. PubMed ID: 20490397.
    Abstract:
    Combined scanning tunneling microscopy (STM), X-rays photoelectron spectroscopy (XPS) and density functional theory (DFT) studies have probed the bonding configurations and mobility of trimethylacetic acid (TMAA) molecules on the TiO(2)(110) surface at RT. Upon TMAA dissociation through deprotonation, two distinctly different types of stable chemisorption configurations of the carboxylate group (TMA) have been identified according to their position and appearance in STM images. In configuration A, two carboxylate O atoms bond to two Ti(4+) cations, while in configuration B one O atom fills the bridging oxygen vacancy (V(O)) with the other O bounded at an adjacent regular Ti(4+) site. Calculated adsorption energies for the configurations A and B are comparable at 1.28 and 1.36 eV, respectively. DFT results also show that TMA may rotate at RT about its O atom that filled the V(O) (in configuration B), with a rotation barrier of approximately 0.65 eV. Both the observation of the constant initial sticking coefficient and preference for TMAA molecules to dissociate at selective sites indicate that TMAA adsorption is mediated by a mobile precursor state. Several possible molecular (physisorbed) states of TMAA have indeed been identified by DFT, all being highly mobile at RT. In contrast, the TMA diffusion in the chemisorbed (dissociative) state is a very slow with a calculated barrier of 1.09 eV for diffusion along the Ti row.
    [Abstract] [Full Text] [Related] [New Search]