Benzene adsorption on Rh(111) : a new perspective on intermolecular interactions and molecular ordering
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The adsorption of benzene on the Rh(111) substrate was investigated through scanning tunneling microscopy (STM) imaging and density functional theory (DFT) calculations. Experiments were carried out at various surface coverages, with the amount of benzene adsorbed determined to influence the molecular adsorption site, the intermolecular interactions, and the interaction between the molecule and the substrate. At a sub-monolayer coverage of the surface, the molecules are disordered and kept apart by a strong inter-adsorbate repulsion, with a preference for the molecule to adsorb on a three-fold hcp hollow site. At high coverage, the preferred adsorption site becomes the two-fold symmetric bridge site, whether as part of the two dense ordered structures that form at high coverage ((2√3×3)rect or (√19×√19)R23.4°) or as part of the disordered array of benzene molecules, which are arranged in formations which resemble the “building blocks” of the ordered overlayers. Despite the adsorption energy for benzene within both dense structures being similar, the (√19×√19)R23.4° overlayer is only observed if the substrate is annealed to 363 K during or after deposition, indicating that the formation of the (√19×√19)R23.4° ordering is inhibited by an activation barrier at lower temperatures and can only be overcome by increasing the temperature of the Rh(111) support.
Treanor , M-J , Garrido Torres , J A , Bromley , C J , Fruchtl , H A & Schaub , R 2018 , ' Benzene adsorption on Rh(111) : a new perspective on intermolecular interactions and molecular ordering ' , Journal of Physical Chemistry C , vol. 122 , no. 22 , pp. 11890-11904 . https://doi.org/10.1021/acs.jpcc.8b02798
Journal of Physical Chemistry C
Copyright © 2018 American Chemical Society. This work has been made available online in accordance with the publisher’s policies. This is the author created accepted version manuscript following peer review and as such may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1021/acs.jpcc.8b02798
DescriptionThe authors acknowledge financial support from the Scottish Funding Council (through EaStCHEM and SRD-Grant HR07003) and from EPSRC (PhD studentships for JAGT − EP/M506631/1, and MJT − EP/K503162/1).
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