Diffusion of Reactants on Dust Surfaces. A Door to Understanding Surface Chemistry in Space

• Applicant: Dr. Alexey Potapov
• Subject Area: Astrophysics and Astronomy ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 569300745

This project is a startup of a new collaboration between the CY Cergy Paris Université (CYU), France and the Friedrich Schiller University (FSU) Jena, Germany. The collaboration will be based on a combination of two experimental techniques available to the groups, namely a laser ablation facility for gas-phase condensation of carbonaceous and siliceous grains at the FSU and an ultra-high vacuum facility coupled to sources for atomic bombardment of surfaces at the CYU. Chemical processes leading to the formation of molecules in astrophysical environments such as the interstellar medium, protoplanetary envelopes, planet-forming disks, and atmospheres of planets can be divided into two groups: gas-phase and grain-surface reactions. It is well-known that surface reaction pathways lead to a greater complexity of molecular species and are also responsible for the formation of key astrophysical molecules such as H2 and H2O. In addition to providing a meeting place for reactants, dust grains act as a third body, allowing the dissipation of excess energy released during bond formation, may act as a catalyst, lowering diffusion barriers for reactants and activation barriers for reactions, and can participate directly (by atoms or functional groups) in surface reactions. To fully understand how surface reactions proceed and the catalytic effect of the surface therein, diffusion must be measured independently. However, laboratory diffusion studies on cosmic dust grain analogues present uncharted territory. Diffusion rates on dust surfaces can be quite different from those on chemically inert surfaces and astrophysically relevant ices that have been studied. The aim of our collaboration is to study diffusion of astrophysically relevant radicals and molecules on the surface of different cosmic dust grain analogues. Our research will provide a step change in the understanding of the surface processes leading to the formation of key simple molecules, such as H2 and H2O, and complex organic and prebiotic molecules in astrophysical environments ranging from diffuse interstellar clouds to planet-forming disks and atmospheres of exoplanets. Our research will thus be directly linked to questions of our astrochemical heritage and the existence of other habitable planets. This will be of interest not only to the astrophysical/astrochemical communities, but also to a much wider public. In addition, our study of the surface diffusion of reactants may lead to new applications of carbonaceous and siliceous nanoparticles in industrial processes, such as oxidation and hydrogen storage.

• DFG Programme: Research Grants
• International Connection: France
• Cooperation Partner: Professor Dr. Emanuele Congiu, Ph.D.