Collings, MP, Frankland, VL, Lasne, J et al. (3 more authors) (2015) Probing model interstellar grain surfaces with small molecules. Monthly Notices of the Royal Astronomical Society, 449 (2). pp. 1826-1833. ISSN 0035-8711
Abstract
Temperature-programmed desorption and reflection-absorption infrared spectroscopy have been used to explore the interaction of oxygen (O2), nitrogen (N2), carbon monoxide (CO) and water (H2O) with an amorphous silica film as a demonstration of the detailed characterization of the silicate surfaces that might be present in the interstellar medium. The simple diatomic adsorbates are found to wet the silica surface and exhibit first-order desorption kinetics in the regime up to monolayer coverage. Beyond that, they exhibit zero-order kinetics as might be expected for sublimation of bulk solids. Water, in contrast, does not wet the silica surface and exhibits zero-order desorption kinetics at all coverages consistent with the formation of an islanded structure. Kinetic parameters for use in astrophysical modelling were obtained by inversion of the experimental data at sub-monolayer coverages and by comparison with models in the multilayer regime. Spectroscopic studies in the sub-monolayer regime show that the C–O stretching mode is at around 2137 cm−1 (5.43 μm), a position consistent with a linear surface–CO interaction, and is inhomogenously broadened as resulting from the heterogeneity of the surface. These studies also reveal, for the first time, direct evidence for the thermal activation of diffusion, and hence de-wetting, of H2O on the silica surface. Astrophysical implications of these findings could account for a part of the missing oxygen budget in dense interstellar clouds, and suggest that studies of the sub-monolayer adsorption of these simple molecules might be a useful probe of surface chemistry on more complex silicate materials.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2015 The Authors. This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | molecular data; molecular processes; methods: laboratory: molecular; dust, extinction |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemistry (Leeds) > Physical Chemistry (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 05 May 2016 12:57 |
Last Modified: | 05 May 2016 12:57 |
Published Version: | https://dx.doi.org/10.1093/mnras/stv425 |
Status: | Published |
Publisher: | Oxford University Press |
Identification Number: | 10.1093/mnras/stv425 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:94949 |