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Chemistry

Virginia Commonwealth University

Chemistry Publications

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Full-Text Articles in Physical Sciences and Mathematics

Vapor Phase Nucleation On Neutral And Charged Nanoparticles: Condensation Of Supersaturated Trifluoroethanol On Mg Nanoparticles, Victor Abdelsayed, M. Samy El-Shall Jan 2007

Vapor Phase Nucleation On Neutral And Charged Nanoparticles: Condensation Of Supersaturated Trifluoroethanol On Mg Nanoparticles, Victor Abdelsayed, M. Samy El-Shall

Chemistry Publications

A new technique is described to study the condensation of supersaturated vapors on nanoparticles under well-defined conditions of vapor supersaturation, temperature, and carrier gas pressure. The method is applied to the condensation of supersaturated trifluoroethanol (TFE) vapor on Mg nanoparticles. The nanoparticles can be activated to act as condensation nuclei at supersaturations significantly lower than those required for homogeneous nucleation. The number of activated nanoparticles increases with increasing the vapor supersaturation. The small difference observed in the number of droplets formed on positively and negatively charged nanoparticles is attributed to the difference in the mobilities of these nanoparticles. Therefore, no …


Kinetics Of Ion-Induced Nucleation In A Vapor-Gas Mixture, Sergey P. Fisenko, David B. Kane, M. Samy El-Shall Jan 2005

Kinetics Of Ion-Induced Nucleation In A Vapor-Gas Mixture, Sergey P. Fisenko, David B. Kane, M. Samy El-Shall

Chemistry Publications

A general solution for the steady-state ion-induced nucleation kinetics has been derived, considering the differences between ion-induced nucleation and homogeneous nucleation. This solution includes a new effect for nucleation kinetics, the interaction of charged clusters with vapor molecules. Analytical expressions for the ion-induced nucleation rate have been obtained for the limiting cases of high and low thermodynamic barriers. The physical explanation of the so-called sign effect is proposed based on multipole expansion of an electric field of the cluster ion. This theory gives good agreement with experiments and is used to elucidate experimentally observed phenomena.