  CO2 ices are known to exist in different astrophysical environments. In spite
of this, its physical properties (structure, density, refractive index) have
not been as widely studied as those of water ice. It would be of great value to
study the adsorption properties of this ice in conditions related to
astrophysical environments. In this paper, we explore the possibility that CO2
traps relevant molecules in astrophysical environments at temperatures higher
than expected from their characteristic sublimation point. To fulfil this aim
we have carried out desorption experiments under High Vacuum conditions based
on a Quartz Crystal Microbalance and additionally monitored with a Quadrupole
Mass Spectrometer. From our results, the presence of CH4 in the solid phase
above the sublimation temperature in some astrophysical scenarios could be
explained by the presence of several retaining mechanisms related to the
structure of CO2 ice.
