Kinetic theories of evaporation

Theories of evaporation and condensation which apply to a wide range of disequilibrium conditions must be based on assumptions regarding the form of the velocity distribution function of vapor molecules at the surface. However, the distribution function describing vapor molecules at the surface and moving away from it is not the same as that which applies to the emission of molecules from the condensed phase. A number of previous treatments of the half-space evaporation problem are shown to be incorrect and an improved solution, taking into account the evaporation coefficient, is presented