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Probing the non-pairwise interactions between CO molecules moving on a Cu(111) surface.
MedLine Citation:
PMID:  22353494     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
The coverage dependent dynamics of CO on a Cu(111) surface are studied on an atomic scale using helium spin-echo spectroscopy. CO molecules occupy top sites preferentially, but also visit intermediate bridge sites in their motion along the reaction coordinate. We observe an increase in hopping rate as the CO coverage grows; however, the motion remains uncorrelated up to at least 0.10 monolayers (ML). From the temperature dependence of the diffusion rate, we find an effective barrier of 98 ± 5 meV for diffusion. Thermal motion is modelled with Langevin molecular dynamics, using a potential energy surface having adsorption sites at top and bridge positions and the experimental data are well represented by an adiabatic barrier for hopping of 123 meV. The sites are not degenerate and the rate changes observed with coverage are modelled successfully by changing the shape of the adiabatic potential energy surface in the region of the transition state without modifying the energy barrier. The results demonstrate that sufficient detail exists in the experimental data to provide information on the principal adsorption sites as well as the energy landscape in the region of the transition state.
Authors:
Pepijn R Kole; Holly Hedgeland; Andrew P Jardine; William Allison; John Ellis; Gil Alexandrowicz
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Publication Detail:
Type:  Journal Article     Date:  2012-02-21
Journal Detail:
Title:  Journal of physics. Condensed matter : an Institute of Physics journal     Volume:  24     ISSN:  1361-648X     ISO Abbreviation:  J Phys Condens Matter     Publication Date:  2012 Mar 
Date Detail:
Created Date:  2012-02-22     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101165248     Medline TA:  J Phys Condens Matter     Country:  England    
Other Details:
Languages:  eng     Pagination:  104016     Citation Subset:  IM    
Affiliation:
Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, UK.
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