Effect of the Tolman Surface Tension Correction on Nucleation in Chemically Reacting Systems

This paper considers the effect of the Tolman surface tension correction on aerosol nucleation and growth in chemically reacting systems. The classical Becker-Döring-Zeldovich(BDZ) theory for homogeneous nucleation rates is modified to include the Tolman correction for the surface tension of small droplets. The modified expression for the nucleation rate is used to simulate aerosol nucleation and growth using the integral model of Friedlander. The Tolman correction is also incorporated into the discrete-sectional numerical algorithm of Rao and McMurry. It is shown that the nucleation rate is substantially increased when the Tolman correction is accounted for. The increase in nucleation rates is especially large for substances with large surface energies and large molecular volumes. Using reasonable values for δ, the Tolman coefficient, good agreement is obtained between theory and data for sulfuric acid number concentrations and size distributions in experiments involving SO2 photooxidation. While the agreement between theory and experiment is encouraging, further experimental work needs to be done to confirm the curvature dependence of the surface tension of small droplets.