Condensation and Evaporation of Solar System Materials

TLDR: In this paper, the theoretical background for fractionation of elemental and isotopic compositions during kinetically controlled evaporation and condensation is explored in some detail, and the theoretical and experimental properties of solar system materials are discussed.

Abstract: The volatile element depletion patterns of planetary size objects and the chemical and isotopic composition of numerous smaller objects such as chondrules and calcium- and aluminum-rich inclusions (CAIs) provide the motivation to consider evaporation and condensation processes in the early solar system. Equilibrium thermodynamic calculations of condensation of phases in the solar nebula provide an important reference with which natural solar system materials can be compared. The theoretical background for fractionation of elemental and isotopic compositions during kinetically controlled evaporation and condensation is explored in some detail. Some parameters can be calculated from first principles, but others must be measured in the laboratory, and a number of evaporation experiments are described and interpreted. Elemental and isotopic fractionations of solar system materials are then intepreted in the context of the theoretical and experimental considerations. A key point is that the processes that led to chondrules and planets appear to have occurred under conditions very close to equilibrium, whereas the processes that led to CAIs involved significant departures from equilibrium.