Atomic scale friction of molecular adsorbates during diffusion
2013 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 138, no 19, 194710- p.Article in journal (Refereed) Published
Experimental observations suggest that molecular adsorbates exhibit a larger friction coefficient than atomic species of comparable mass, yet the origin of this increased friction is not well understood. We present a study of the microscopic origins of friction experienced by molecular adsorbates during surface diffusion. Helium spin-echo measurements of a range of five-membered aromatic molecules, cyclopentadienyl, pyrrole, and thiophene, on a copper(111) surface are compared with molecular dynamics simulations of the respective systems. The adsorbates have different chemical interactions with the surface and differ in bonding geometry, yet the measurements show that the friction is greater than 2 ps(-1) for all these molecules. We demonstrate that the internal and external degrees of freedom of these adsorbate species are a key factor in the underlying microscopic processes and identify the rotation modes as the ones contributing most to the total measured friction coefficient.
Place, publisher, year, edition, pages
2013. Vol. 138, no 19, 194710- p.
Atom and Molecular Physics and Optics
IdentifiersURN: urn:nbn:se:su:diva-92022DOI: 10.1063/1.4804269ISI: 000319291600033OAI: oai:DiVA.org:su-92022DiVA: diva2:637339
FunderSwedish Research Council
Sevarl other funders2013-07-172013-07-152013-07-25Bibliographically approved