The project is being developed by the participation of (a total, recruited at different stages) 9 PhD students, 5 postdocs and 1 technician. Three PhD theses have been sucessfully defended. In the following, the main work done is summarized.
We atomistically modelled in a realistic manner different interstellar grain surfaces: (i) those constituting the ice mantles, like pure water ice, pure CO ice and water:CO mixtures; (ii) refractory materials present in interstellar, cometary and meteoritic grains, like silicates, silica with metals, and iron sulphides. Dedicated electronic microscopy and nanoindentation measurements have been performed on meteoritic samples to determine their structure, composition and mechanical properties.
Atomistic simulations of the adsorption of a wide set of astrochemically-relevant species (O-, N- and S-containing compounds, and interstellar complex organic molecules, iCOMs) on icy surfaces and silicates have been performed. Unprecedented, accurate binding energies have been obtained, which are crucial in numerical models to explain the chemistry present in space.
Different chemical reactions occurring on the grains have been simulated: (i) formation of simple interstellar species (e.g. H2O, NH3, CH3OH), (ii) formation of organic compounds (e.g. iCOMs, hydrocarbons and alcohols), and (iii) formation of biomolecules (e.g. sugars, amino acids and nucleobases).
Simulations serve to determine the capability of interstellar water ices to act as third bodies, in which they absorb the energy released by the reactions, hence stabilizing the formed products. This has been the case for the formation of NH3 and iCOMs, where moreover, the energy dissipation mechanisms were deciphered.
Results provide deeper insights on the roles played by the grains in the interstellar chemistry. In some cases, grains accelerate the reactions (they act as chemical catalysts) by providing alternative less energetic synthetic paths. In others, grains retain the reactants on the surfaces allowing their encountering. For icy grains, a component of the ice is a reactant itself (grains act as reactant suppliers). Finally, for coupling reactions, grains act as efficient third bodies.
Results are being published in scientific articles in top-ranked journals and presented in different international congresses, mostly in the form of oral presentations but also posters. Research group activities are announced in our website (
https://www.quantumgrain.eu(s’ouvre dans une nouvelle fenêtre)) and X account (@QuantumGrain), where we also disseminate our outreach activities, (e.g. popular science articles, blog posts and podcasts,
https://www.quantumgrain.eu/outreach(s’ouvre dans une nouvelle fenêtre)).
