Isotope Fractionation of Light Elements Upon Ionization: Cosmochemical and Geochemical Implications

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Light elements such as hydrogen and nitrogen present large isotope variations among solar system objects and reservoirs (including planetary atmospheres) that remain unexplained at present. Works based on theoretical approaches are model-dependent and do not reach a consensus. Laboratory experiments are required in order to develop the underlying physical mechanisms. The aim of the project is to investigate the origins of and processes responsible for isotope variations of the light elements and noble gases in the Solar System through an experimental approach involving ionization of gaseous species. We will also investigate mechanisms and processes of isotope fractionation of atmophile elements in planetary atmospheres that have been irradiated by solar UV photons, with particular reference to Mars and the early Earth. Three pathways will be considered: (i) plasma ionisation of gas mixtures (H2-CO-N2-noble gases) in a custom-built reactor; (ii) photo-ionisation and photo-dissociation of the relevant gas species and mixtures using synchrotron light; and (iii) UV irradiation of ices containing the species of interest. The results of this study will shed light on the early Solar System evolution and on processes of planetary formation.