NSF-BSF: A Coordinated Study of the Isotope effect in the Vacuum Ultraviolet Photodissociation of Astronomically Important Molecules: Implications for the Early Solar System

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Understanding the isotopic composition of meteorites and planetary atmospheres is important to understanding the early evolutionary stages of the Solar Nebula and gaining insight into planet formation and evolution. This research project is a coordinated experimental and theoretical study of how the dissociation of molecular nitrogen and its isotopically substituted forms containing the heavy atom nitrogen-15 by ultraviolet (UV) light influences the nitrogen-15 content of compounds in space. Results from the study will allow astronomers to accurately interpret the observed range in isotopic composition of nitrogen-bearing molecules in the atmospheres of planetary bodies and surfaces of meteorites in the Solar System. Supported jointly by the National Science Foundation (NSF) and the US-Israel Binational Science Foundation (BSF), this project will foster a collaboration between an experimental research group in the US and a computational research group in Israel, train students and postdoctoral researchers, and conduct science outreach to a diverse population in the San Diego area.Using the Advanced Light Source of the Lawrence Berkeley National Laboratory, the US group will perform experiments on the vacuum-UV photodissociation of molecular nitrogen and its nitrogen-15 isotopologues. High-level theoretical calculations from the Israeli group will guide the experiments and will be refined by the experimental results. The investigations will show how molecular nitrogen undergoes photodissociation as a function of wavelength and establish the fraction of nitrogen-15 that is incorporated into molecules. Data from this project will be of immediate applicability to physico-chemical models of a variety of astronomical environments. A fundamental mechanistic understanding of isotopic fractionation driven by vacuum-UV photodissociation will also inform similar studies of other astronomically important molecules.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.