Effect of condensation rate enhancement factor on 3‐nm (diameter) particle formation in binary ion‐induced and homogeneous nucleation

Abstract

Charges in aerosol particles enhance condensation flux of polar molecules onto particles. In this paper, the effect of condensation enhancement due to Coulomb forces was investigated. The main aim is to find out the upper limit of the effect and its significance on nucleation mode particle growth dynamics. The enhancement factor seems to be below 5 for charged particle growth from 1.5 to 10 nm in particle radius. However, only a limited amount of particle population is charged, and the overall effect maximum effect was less than 2. This, combining with a vapor concentration of about 1 × 107 molecules cm−3, is enough to explain nucleation mode growth of 1 nm h−1. Also, the effect of enhanced condensation on total observed aerosol concentration was simulated using an aerosol dynamic model. In the case of neutral nucleation, the effect is negligible for small enhancement factor (EF). With higher EF the final concentration was found to decrease. In the case of ion‐induced nucleation the effect varied with preexisting particle concentration and enhancement factor.