Volume 245, 2023

Infrared photodesorption of CO from astrophysically relevant ices studied with a free-electron laser

Abstract

The infrared excitation and photodesorption of carbon monoxide (CO) and water-containing ices have been investigated using the FEL-2 free-electron laser light source at the FELIX laboratory, Radboud University, The Netherlands. CO–water mixed ices grown on a gold-coated copper substrate at 18 K were investigated. No CO photodesorption was observed, within our detection limits, following irradiation with light resonant with the C–O vibration (4.67 μm). CO photodesorption was seen as a result of irradiation with infrared light resonant with water vibrational modes at 2.9 μm and 12 μm. Changes to the structure of the water ice, which modifies the environment of the CO in the mixed ice, were also seen subsequent to irradiation at these wavelengths. No water desorption was observed at any wavelength of irradiation. Photodesorption at both wavelengths is due to a single-photon process. Photodesorption arises due to a combination of fast and slow processes of indirect resonant photodesorption (fast), and photon-induced desorption resulting from energy accumulation in the librational heat bath of the solid water (slow) and metal-substrate-mediated laser-induced thermal desorption (slow). Estimated cross-sections for the slow processes at 2.9 μm and 12 μm were found to be ∼7.5 × 10−18 cm2 and ∼4.5 × 10−19 cm2, respectively.

Graphical abstract: Infrared photodesorption of CO from astrophysically relevant ices studied with a free-electron laser

Associated articles

Article information

Article type
Paper
Submitted
31 Jan 2023
Accepted
22 Mar 2023
First published
24 Mar 2023
This article is Open Access
Creative Commons BY license

Faraday Discuss., 2023,245, 446-466

Infrared photodesorption of CO from astrophysically relevant ices studied with a free-electron laser

E. R. Ingman, D. Laurinavicius, J. Zhang, J. G. M. Schrauwen, B. Redlich, J. A. Noble, S. Ioppolo, M. R. S. McCoustra and W. A. Brown, Faraday Discuss., 2023, 245, 446 DOI: 10.1039/D3FD00024A

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