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Becker-Döring rate equations for heterogeneous nucleation, with direct vapour deposition and surface diffusion mechanisms

Kroon, CMLV; Ford, IJ; (2011) Becker-Döring rate equations for heterogeneous nucleation, with direct vapour deposition and surface diffusion mechanisms. Atmospheric Research , 101 (3) 553 - 561. 10.1016/j.atmosres.2010.12.019. Green open access

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Abstract

We develop a set of microscopic rate equations describing the growth and decay of molecular clusters adsorbed onto a seed particle. Such Becker–Döring equations are fundamental to descriptions of homogeneous nucleation, but do not appear to have been developed for the rather more complicated case of heterogeneous nucleation. We show that the familiar Fletcher theory of heterogeneous nucleation emerges from such a Becker–Döring description, but only if the concentration of adsorbed single molecules on the surface is estimated in a rather rudimentary manner. For small seed particles, this approach fails and one needs a proper Becker–Döring approach to provide a better estimate. The change in predicted nucleation rate can be several orders of magnitude for nanometre-size seed particles. We go on to include into the Becker–Döring treatment the processes of growth and decay of clusters by monomer surface diffusion on the seed. We use recent high quality experimental data to show that the latter process can make only a small contribution to the nucleation current for nanoparticle seeds. We also use the data to demonstrate that the traditional Fletcher theory fails to account for critical sizes and nucleation currents correctly, and that a modification to the implied underlying cluster properties is necessary.

Type: Article
Title: Becker-Döring rate equations for heterogeneous nucleation, with direct vapour deposition and surface diffusion mechanisms
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.atmosres.2010.12.019
Publisher version: http://dx.doi.org/10.1016/j.atmosres.2010.12.019
Language: English
Additional information: © 2011. This manuscript version is published under a Creative Commons Attribution Non-commercial Non-derivative 4.0 International licence (CC BY-NC-ND 4.0). This licence allows you to share, copy, distribute and transmit the work for personal and non-commercial use providing author and publisher attribution is clearly stated. Further details about CC BY licences are available at http://creativecommons.org/licenses/by/4.0.
Keywords: Heterogeneous nucleation; Becker–Döring equations; Fletcher theory
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/1323232
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