Formation And Trapping Of CO2 From Cryogenic Irradiation Of Carbonate

The detection of CO₂ on the Jovian satellite Europa by Galileo NIMS and recent mapping of the leading side by JWST has revealed that it is most concentrated in geologically young terrains, and its v3 asymmetric stretch appears as a spectral doublet centered at 4.25 and 4.27 um.

Since crystalline CO₂ is unstable at Europan surface conditions, this observation implies an active source and a trapping medium, which may be separate. To this end, several hypotheses have been proposed, but no laboratory work has successfully reproduced the spectral features of CO₂ on Europa so far.

Radiolyzed carbonates have also been discussed as plausible precursors and host materials for CO₂, though their role has not been experimentally validated in a Europa-like environment. Here, we report the first laboratory experiments investigating CO₂ production from carbonate salts exposed to 10 keV electron irradiation at 50, 100, and 120 K in ultrahigh vacuum.

Using diffuse reflectance FTIR spectroscopy, we observe the emergence, growth, and saturation of an absorption doublet centered near 4.25 and 4.27 um, consistent with the CO₂ v3 band. Postirradiation thermal desorption studies using residual gas analysis reveal that the radiolytically formed CO₂ is stable at temperatures beyond Europa’s surface.

This work provides the first experimental evidence that low-energy electron irradiation of carbonates in cryogenic, vacuum conditions can produce and retain CO₂, and suggests that carbonates can serve as endogenous reservoirs of CO₂ on irradiated icy bodies in the outer solar system.

Ashma Pandya, Swaroop Chandra, Michael E. Brown

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Chemical Physics (physics.chem-ph)
Cite as: arXiv:2604.27177 [astro-ph.EP] (or arXiv:2604.27177v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2604.27177
Focus to learn more
Journal reference: The Planetary Science Journal, 7:93 (7pp), 2026 April
Related DOI:
https://doi.org/10.3847/PSJ/ae595b
Focus to learn more
Submission history
From: Ashma Pandya
[v1] Wed, 29 Apr 2026 20:26:46 UTC (961 KB)
https://arxiv.org/abs/2604.27177

Astrobiology, astrochemistry,