Evaporation Processes in the Solar Nebula and Chemical and Isotopic Fractionation

At low pressure conditions of the solar nebula, condensation and evaporation are the major phase transitions that caused chemical and isotopic fractionation, which may be responsible for planetary and meteoritical chemical fractionation. In order to describe the fractionation quantitatively as a time-dependent process, kinetic factors such as evaporation rates, fractionation factors, nucleation rates, reaction rates between gas and solids, and diffusion rates of elements in major minerals and rarely in melts should be obtained. Experimental work on evaporation of minerals and melts has enabled us to understand the roll of various kinetics during evaporation, and their parameters have been obtained for most important reactions. Theoretical treatment of kinetic processes has been also developed for chemical and isotopic fractionation due to evaporation with or without contribution of diffusion in condensed phases. Combination of experimental and theoretical work along with solar nebula modeling becomes successful in describing the development of chemical and isotopic fractionation in the solar system. The recent progress in laboratory evaporation experiments and theoretical studies is reviewed in this paper.