Desorption of organic molecules from interstellar ices, combining experiments and computer simulations: Acetaldehyde as a case study

Context. Explaining the presence of complex organic molecules (COMs) in interstellar environments requires a thorough understanding physics and chemistry occurring interplay between gas phase surfaces. Experiments computer simulations are pivotal building comprehensive catalogue processes relevance for build up those environments. Aims. We combine experiments with tailored to study desorption dynamics acetaldehyde CH 3 CHO – an important precursor cold - on amorphous solid water first time. Our goals this paper twofold. Firstly, we want contextualise role molecule evolution space. Secondly, suggest joint scheme produce quantitative information magnitudes based combination computations experiments. This can be adopted refine measurements other molecules. Methods. determined energies pre-exponential factors theoretically using molecular that semi-empirical density functional calculations. also performed temperature-programmed top non-porous water. The theoretical experimental results allows us derive reliable quantities, which required COMs (iCOMs) atop ices. Results. average found desorbing from (np-ASW) surfaces 3624 K 3774 K, respectively. factor is v theo = 2.4 × 10 12 s −1 while it was possible constrain magnitude 12±1 . Conclusions. comparison COMs, such as NH 2 or NO, shows more volatile. Therefore, that, consideration binding energy, should undergo preferential during ice-sublimation hot cores enriching gas-phase particular component. In addition, overall low energy suggests early return pre-stellar due non-thermal effects (i.e. reactive cosmic-ray-induced desorption). could explain prevalence cores. Dedicated laboratory efforts confirm last point.