text: Evaporation and condensation can give rise to both kinetic and equilibrium isotope effects. While equilibrium mass fractionation is present evaporation and condensation, it is negligible compared to kinetic effects. During condensation, the condensate is enriched in the light isotope, whereas in evaporation, the gas phase is enriched in the light isotope.  Using the kinetic theory of gases, for Fe/Fe, a fractionation factor of α = 1.01835 for the evaporation of a pool containing equimolar amounts of Fe and Fe. In evaporation experiments, the evaporation of FeO at 1,823 K gave a fractionation factor of α = 1.01877. Presently, there have been no experimental attempts to determine the Fe/Fe fractionation factor of condensation.