Transient mobility mechanisms of deposited metal atoms on insulating surfaces: Pd on MgO (100)

Gao, David Z., Watkins, Matthew and Shluger, Alexander L. (2012) Transient mobility mechanisms of deposited metal atoms on insulating surfaces: Pd on MgO (100). Journal of Physical Chemistry C, 116 (27). pp. 14471-14479. ISSN 1932-7447

Full content URL: http://pubs.acs.org/doi/full/10.1021/jp303951y

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Transient mobility mechanisms of deposited metal atoms on insulating surfaces: Pd on MgO (100)

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Abstract

The importance and mechanisms of transient mobility of atoms and molecules adsorbing at surfaces have been a subject of controversy for many years. We used classical molecular dynamics simulations to examine transient mobility of Pd atoms adsorbing on the MgO (100) surface with incident kinetic energies not exceeding 0.4 eV. The calculations show that deposited Pd atoms exhibit high mobility at temperatures below 80 K where the contribution from thermal diffusion processes should be negligible. For our selected deposition conditions, aimed at simulation of Pd cluster growth experiments, an estimated 76 of the impinging Pd atoms are expected to travel up to 20 à away from the collision site before capture on a 5 K surface. We find that mobility of metal atoms on oxide surfaces is expected to decrease with decreasing incident energy and increase with decreasing incident angle. Comparison with prior studies highlights similarities and differences with other surface diffusion processes, such as long jumps. At higher surface temperatures, the observed mobility will mainly be due to thermally activated processes rather than transient mobility mechanisms. Atoms that exhibit transient mobility upon deposition may quickly migrate to surface features and defects affecting kinetics of growth and structures of nanoclusters and surface layers. © 2012 American Chemical Society.

Keywords:Classical molecular dynamics, Deposited metal, Deposition conditions, Diffusion process, High mobility, Incident angles, Incident energy, Insulating surfaces, Metal atoms, MgO(1 0 0), Oxide surface, Pd atoms, Pd clusters, Surface feature, Surface layers, Surface temperatures, Thermally activated process, Growth kinetics, Molecular dynamics, Surface defects
Subjects:F Physical Sciences > F170 Physical Chemistry
Divisions:College of Science > School of Mathematics and Physics
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ID Code:17706
Deposited On:19 Jun 2015 10:33

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