10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
A Unifying Identity for the Work of Cluster Formation in Heterogeneous and Homogeneous Nucleation Theory
ROBERT MCGRAW, Paul M. Winkler, Paul E. Wagner, Brookhaven National Laboratory
Abstract Number: 1434 Working Group: Aerosol Physics
Abstract Nucleation in the atmosphere is responsible for the formation of new particles that can subsequently grow to exert a significant impact on global climate directly through the scattering and absorption of solar radiation and indirectly by serving as sites for cloud droplet condensation. There is evidence that both homogeneous nucleation and heterogeneous nucleation pathways contribute to this process. Indeed, the interesting two-stage model of Kulmala and co-workers: heterogeneous nucleation of (most likely) oxidized organic vapors on stabilized 1-2 nm neutral cluster condensation sites formed from the gas phase, effectively eliminates distinction between heterogeneous and homogeneous nucleation mechanisms as the condensation sites approach molecular size. A unifying identity is derived in the present study relating the surface and volume components of the reversible work of cluster formation. Shown to generalize two early thermodynamic relationships of Gibbs, the new result is demonstrated here for Fletcher’s model of heterogeneous nucleation on flat and curved substrates and in the homogeneous nucleation limit, for clusters of non-critical as well as critical size, and for application to non-classical (molecular-based) theories. The new identity can serve as a check on the consistency of complicated theoretical expressions and numerical calculations and help guide interpretation of measurements.