Quantum chemistry computations of the adsorption, diffusion and reactivity of atoms and light radicals on the surfaces of interstellar grains

Abstract

This thesis presents a comprehensive study of the chemistry of interstellar grains using state-of-the-art computational techniques. Understanding interstellar grain chemistry is essential in unraveling the chemical evolution of the universe, but it is limited by the challenges of reproducing and characterizing processes in laboratory experiments and astrochemical models. To overcome these limitations, this thesis focuses on several key surface processes, including adsorption, reactivity, diffusion, and energy dissipation. By using computational techniques to provide atomic-level information, this research complements observations and models, shedding new light on the mechanisms, energetics, and dynamics of interstellar processes._x000D_ _x000D_ Specifically, this work investigates the interactions of several interstellar molecules with interstellar ice surface models, the reactivity of the carbon atom on H2O- and CO-rich ices, the energy dissipation process in exothermic surface reactions (such as NH3 formation) and atomic interstellar diffusion. By simulating these processes in silico, this research reveals new insights into the mechanisms, energetics and dynamics of interstellar processes that are not accessible through other methods._x000D_ _x000D_ The contribution of this research to the field of interstellar chemistry is twofold. First, it provides an atomic-level understanding of the chemical processes occurring on interstellar grains such as the formation and evolution of complex organic molecules. Second, it provides important and accurate parameters that can be used as input for astrochemical models, an essential tool for interpreting astronomical observations._x000D_ _x000D_ Overall, this thesis advances our understanding of interstellar grain chemistry by providing a more complete and nuanced picture of the chemical processes that occur on interstellar grains, and by offering new insights into the formation and evolution of complex organic molecules in the universe.

Date of Award	22 May 2023
Original language	English
Supervisor	Albert Rimola Gibert (Director) & Maria Sodupe Roure (Director)