Thermal desorption of methanol in hot cores. Study with a quartz crystal microbalance

Abstract

[EN] The desorption process of methanol in the hot cores of massive young stars is addressed in this work. The study of pure methanol ice and when it is mixed or layered with water allows a better understanding of the physical and chemical processes which could have occurred during the formation of methanol and it is possible to infer the range of temperatures within which methanol can be found in the gas phase in these scenarios. The goal of this study was to model the desorption process of methanol as pure ice and mixed or layered with water under the conditions present in the early stages of hot cores whichcharacterize young star formation. The simulations of desorption of methanol, when it stands alone, performed in this work were compared to the values obtained by other authors to validate the method presented. In this work, the desorption of a water: methanol mixture under astrophysical conditions is also simulated. The theoretical results obtained for layered mixtures match with the temperatures at which an increase of the presence of methanol in the gas phase is detected when young massive mass stars are observed. This study has been performed using the frequency variation of a quartz crystal microbalance which provides a direct measure of the desorbing molecules during the experiments. This process was modelled using the Polanyi-Wigner equation and applied to astrophysical scenarios.