Ozone Production in Electron Irradiated CO2:O2 Ices

TL;DR

This study investigates ozone formation in CO2:O2 ice mixtures under 1 keV electron irradiation at 20 K, providing insights into surface chemistry relevant to icy moons and future space missions.

Contribution

It quantifies ozone production in diverse CO2:O2 ice analogues under electron irradiation and analyzes spectral features, expanding understanding of icy moon surface chemistry.

Findings

Ozone abundance varies with ice composition.

Spectral analysis reveals shape and profile changes of O3 features.

Results inform models of icy moon surface chemistry.

Abstract

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.