Issue 28, 2012

UV photodesorption of interstellar CO ice analogues: from subsurface excitation to surface desorption

Abstract

Carbon monoxide is after H2 the most abundant molecule identified in the interstellar medium (ISM), and is used as a major tracer for the gas phase physical conditions. Accreted at the surface of water-rich icy grains, CO is considered to be the starting point of a complex organic – presumably prebiotic – chemistry. Non-thermal desorption processes, and especially photodesorption by UV photons, are seen as the main cause that drives the gas-to-ice CO balance in the colder parts of the ISM. The process is known to be efficient and wavelength-dependent, but, the underlying mechanism and the physical–chemical parameters governing the photodesorption are still largely unknown. Using monochromatized photons from a synchrotron beamline, we reveal that the molecular mechanism responsible for CO photoejection is an indirect, (sub)surface-located process. The local environment of the molecules plays a key role in the photodesorption efficiency, and is quenched by at least an order of magnitude for CO interacting with a water ice surface.

Graphical abstract: UV photodesorption of interstellar CO ice analogues: from subsurface excitation to surface desorption

Article information

Article type
Paper
Submitted
12 Apr 2012
Accepted
14 May 2012
First published
14 May 2012

Phys. Chem. Chem. Phys., 2012,14, 9929-9935

UV photodesorption of interstellar CO ice analogues: from subsurface excitation to surface desorption

M. Bertin, E. C. Fayolle, C. Romanzin, K. I. Öberg, X. Michaut, A. Moudens, L. Philippe, P. Jeseck, H. Linnartz and J. Fillion, Phys. Chem. Chem. Phys., 2012, 14, 9929 DOI: 10.1039/C2CP41177F

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