  The detection of ozone (O3) in the surface ices of Ganymede, Jupiters largest
moon, and of the Saturnian moons Rhea and Dione, has motivated several studies
on the route of formation of this species. Previous studies have successfully
quantified trends in the production of O3 as a result of the irradiation of
pure molecular ices using ultraviolet photons and charged particles (i.e., ions
and electrons), such as the abundances of O3 formed after irradiation at
different temperatures or using different charged particles. In this study, we
extend such results by quantifying the abundance of O3 as a result of the 1 keV
electron irradiation of a series of 14 stoichiometrically distinct CO2:O2
astrophysical ice analogues at 20 K. By using mid-infrared spectroscopy as our
primary analytical tool, we have also been able to perform a spectral analysis
of the asymmetric stretching mode of solid O3 and the variation in its observed
shape and profile among the investigated ice mixtures. Our results are
important in the context of better understanding the surface composition and
chemistry of icy outer Solar System objects, and may thus be of use to future
interplanetary space missions such as the ESA Jupiter Icy Moons Explorer and
the NASA Europa Clipper missions, as well as the recently launched NASA James
Webb Space Telescope.
