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Electron-induced Molecular Dissociation at a Surface Leads to Reactive Collisions at Selected Impact Parameters

Abstract

Crossed molecular beams of gases have given definitive information concerning the dynamics of chemical reactions. The results have, however, of necessity been averaged over collisions with impact parameters ranging from zero to infinity, obscuring the effect of this important variable. Here we employ a method by which impact parameter averaging is suppressed in surface reaction. We aim a highly-collimated reactive ‘projectile’ molecule along a surface at a stationary adsorbed ‘target’ molecule, both projectile and target being observed by Scanning Tunnelling Microscopy (STM). The projectile was CF2 recoiling from electron-induced bond-breaking in chemisorbed CF3 on Cu(110) at 4.6 K. The collimation of the resulting CF2 ‘surface-molecular-beam’ restricted it to a lateral spread of  1 as a consequence of its interaction with the Cu-rows below. This collimation was modelled by molecular dynamics. In the experiments the recoiling CF2 projectile was aimed, successively, at impact parameters b = 0 and + 3.6 Å at a chemisorbed second CF2, or b = + 1.8 Å at chemisorbed I-atom, or b = – 4.0, b = – 0.4 and b = + 3.2 Å at a chemisorbed vinyl radical. The pattern of reactive and non-reactive scattering was determined by STM. These collimated surface-molecular-beams have the potential to aim molecular projectiles with selected impact parameters at the many target species identifiable at a surface by STM.

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Publication details

The article was received on 27 Sep 2018, accepted on 29 Oct 2018 and first published on 30 Oct 2018


Article type: Paper
DOI: 10.1039/C8FD00137E
Citation: Faraday Discuss., 2018, Accepted Manuscript
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    Electron-induced Molecular Dissociation at a Surface Leads to Reactive Collisions at Selected Impact Parameters

    J. C. Polanyi, K. Anggara, L. Leung, M. J. Timm and H. Zhixin, Faraday Discuss., 2018, Accepted Manuscript , DOI: 10.1039/C8FD00137E

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