Nucleation on an Insoluble Foreign Surface

FIGURE 11.13 Cluster formation on an insoluble flat surface. 0 is the contact angle between the cluster and the flat substrate. 

The discussion above applies to heterogeneous nucleation on flat surfaces. For atmospheric particles the curvature of the surface complicates the situation. Fletcher (1958) showed that the free energy of formation AG of an embryo of critical radius r on a spherical nucleus of radius R is given by 

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