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Mass Transport in Surface Diffusion of van der Waals Bonded Systems - Boosted by Rotations?

Hedgeland, H, Sacchi, Marco, Singh, P, McIntosh, AJ, Jardine, AP, Alexandrowicz, G, Ward, DJ, Jenkins, SJ, Allison, W and Ellis, J (2016) Mass Transport in Surface Diffusion of van der Waals Bonded Systems - Boosted by Rotations? Journal of Physical Chemistry Letters, 7 (23). pp. 4819-4824.

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Abstract

Mass-transport at a surface is a key factor in heterogeneous catalysis. The rate is determined by excitation across a translational barrier and depends on the energy landscape and the coupling to the thermal bath of the surface. Here we use helium spin-echo spectroscopy (HeSE) to track the microscopic motion of benzene adsorbed on Cu(001) at low coverage (θ ∼ 0.07 ML). Specifically, our combined experimental and computational data determine both the absolute rate and mechanism of the molecular motion. The observed rate is significantly higher by a factor of 3.0±0.1 than is possible in a conventional, point-particle model and can only be understood by including additional molecular (rotational) coordinates. We argue that the effect can be described as an entropic contribution that enhances the population of molecules in the transition state. The process is generally relevant to molecular systems and illustrates the importance of the pre-exponential factor alongside the activation barrier in studies of surface kinetics.

Item Type: Article
Subjects : Chemistry
Divisions : Faculty of Engineering and Physical Sciences > Chemistry
Authors :
NameEmailORCID
Hedgeland, HUNSPECIFIEDUNSPECIFIED
Sacchi, Marcom.sacchi@surrey.ac.ukUNSPECIFIED
Singh, PUNSPECIFIEDUNSPECIFIED
McIntosh, AJUNSPECIFIEDUNSPECIFIED
Jardine, APUNSPECIFIEDUNSPECIFIED
Alexandrowicz, GUNSPECIFIEDUNSPECIFIED
Ward, DJUNSPECIFIEDUNSPECIFIED
Jenkins, SJUNSPECIFIEDUNSPECIFIED
Allison, WUNSPECIFIEDUNSPECIFIED
Ellis, JUNSPECIFIEDUNSPECIFIED
Date : 10 November 2016
Identification Number : 10.1021/acs.jpclett.6b02024
Copyright Disclaimer : Copyright © 2016 American Chemical Society
Depositing User : Symplectic Elements
Date Deposited : 11 Nov 2016 15:56
Last Modified : 10 Nov 2017 02:08
URI: http://epubs.surrey.ac.uk/id/eprint/812821

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