CO2 Infrared Spectra On Silicate Dust Grain Analogs: Implications For JWST Observations

Carbon dioxide is one of the three most abundant species within the ice mantles around dust grains inside molecular clouds.

Since a substantial amount of interstellar grains is made of siliceous materials, we have studied the infrared profile of CO₂ deposited on top of a bare and ice-coated amorphous silicate (MgFeSiO₄) film using reflection absorption infrared spectroscopy (RAIRS).

In contrast to a metal surface, the CO₂ IR profile shows a relaxation of the metal surface selection rule in the presence of the bare MgFeSiO₄ dust grain analog, which brings the IR profile closer to the observational spectra while maintaining the sensitivity of RAIRS. Experiments with the underlying CO and CH₄ ices show that their presence facilitates structural changes toward crystalline ice for the deposited CO₂ at much lower temperatures than on the polar ice layers.

Warming-up experiments of CO₂ showed that it tends to stay on the silicate surface for much longer than on the gold surface without the silicate layer. We noticed for the first time a split in the ¹³CO₂ IR feature on the pure or ice-covered silicate grain as a marker for the onset of diffusion.

The laboratory ¹³CO₂ profile then closely resembles recent JWST observations of this feature around young and embedded protostars, suggesting that it can be linked to the observed feature.

Tushar Suhasaria, Vanessa Leuschner, Cornelia Jaeger, Caroline Gieser, Thomas Henning

Comments: 13 pages, 6 figures, 2 tables
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2507.00836 [astro-ph.GA] (or arXiv:2507.00836v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2507.00836
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Submission history
From: Tushar Suhasaria Dr
[v1] Tue, 1 Jul 2025 15:08:11 UTC (363 KB)
https://arxiv.org/abs/2507.00836
Astrobiology,