The atom velocity distribution function in the process of liquid evaporation

Analytical expressions determining the velocity distribution function of evaporating particles were obtained for evaporation into vacuum. The formulas are compared with numerical simulation results; the coincidence can be treated as sufficiently good. The particle distribution function over the longitudinal, i.e., directed from evaporation surface, velocity turns out to be significantly non-Maxwellian. The distribution function over the transverse projections of the velocity is Maxwellian but with a distribution modulus different from the evaporating liquid temperature T. The mean energy of a particle escaping from the surface is 2kT.