Prebiotic catalytic processes in space and in laboratory

Laboratory experiments have shown that different chemical-physical mechanisms are responsible for the richness of molecules observed in space. Surface catalysis at low temperature by dust is considered necessary to justify the presence of, e.g., H2, H2O or CO2, as demonstrated experimentally. However, to describe the presence of more complex molecules, or radicals and even organic refractory material, irradiation processes due to ions and UV photons are required.

Even though water is the main constituent in icy mantles in space, its chemical origin is not well understood. The accepted reaction scheme envisages water ice formed on the surfaces of grains via three different routes: hydrogenation of O, O2, and O3. When accreted on bare solid surface, water provides a medium for a rich chemistry that leads to the formation of molecules of biogenic relevance, such as formaldehyde, methanol, and glycoaldehyde. Moreover, there is much interest in understanding how water was delivered to Earth and the source of water on asteroids. However, the observed H2O ice abundance cannot be explained by direct accretion from the gas phase only and the exact mechanism by which water ice is formed is not understood. New solid state astrochemical laboratory results in which one of these routes is tested will be presented

Furthermore, formamide is confirmed to be a promising route to understand the first chemical steps that brought simple C-bearing molecules towards largely complex mixtures of bio-macro-molecules. In fact, a large suite of pyrimidines and purines has been synthesized using only formamide in the presence of cosmic-dust analogue. In this work the reactivity of the formamide in presence of titanium dioxide is presented to investigate the role of UV irradiation on bio-molecules formation in space.