The recombination or combination time in expressions for volume recombination and combination of air ions and other aerosol particles

A simple relationship, 1/η = 1/ηBF + 1/ηG, exists between η, a general expression for volume recombination or combination coefficients, and its particular expressions, ηBF, in the diffusion-mobility approach (as by Bricard and Fuchs), and ηG, when the central forces acting between the particles to be combined are taken into account (as by Gunn). The reciprocal combination coefficient 1/η may be regarded as a combination or encountering time θ. For the concentrations [i] = [k] = 1 cm−3, the reciprocal recombination or combination coefficient for two species of particles (i and k) is 1/η = dt/- d[i] = dt/- d[k]. For d[i] = d[k] = − 1 cm−3, 1/η = θ is the recombination or combination time for two particles to be combined at unit concentrations. θ = θD + θΔ, where θD is the time for the diffusion-mobility stage, and θΔ is the time for the stage in the closest spacing between the particles, where the undisturbed diffusion-mobility treatment is not more valid. Using these time periods, it can be shown that. DOI: 10.1111/j.2153-3490.1966.tb00277.x