In this work, we focus on the study of radiation induced desorption processes
that occurred in acetonitrile ice irradiated by broadband X-rays (6 eV to 2
keV) monitored by FTIR spectroscopy at different radiation fluences. In a
previous work, we used the PROCODA code to derive the chemical evolution of the
ice. Here, we have obtained that the acetonitrile desorbed column density is at
least two orders of magnitude larger than the desorbed column densities of
daughter or granddaughter molecular species at chemical equilibrium stage. This
indicates that total desorption column density is mainly governed by the father
molecule, as also previously hypothesized in experimental studies. This occurs
basically because the acetonitrile column density is larger than the other
ones. In particular, at chemical equilibrium acetonitrile desorption column
density represents almost 98\% of the total, while it is close to 1\% for H, CN
and CH2β, the species with larger molecular desorption percentages at
chemical equilibrium. Another derived quantity is what we called intrinsic
desorption rate, which is a number per second for individual species. Some of
the larger intrinsic desorption rates were: CH3βCN (6.2Γ10β6), CN
(6.2Γ10β6), H (5.7Γ10β6), CH2β (5.7Γ10β6)
and C2βN2β (4.4Γ10β6). These results help to put constrain in
astrochemical models and can be also useful to clarify some astronomical radio
observations.Comment: To appear in MNRA