Impact of surface heterogeneity on IR line profiles of adsorbed carbon monoxide on models of interstellar grain surfaces

Skandar Taj, Alexander Rosu-Finsen, Martin R. S. McCoustra

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Surface heterogeneity of model amorphous silica films used as a model for interstellar grain surfaces is revealed through the application of the pre-exponential optimized inversion method to previously reported sub-monolayer thermal desorption studies of carbon monoxide (CO) desorption. The impact of that surface heterogeneity, as represented by the coverage dependence of the CO activation energy for desorption from the amorphous silica surface, on the IR spectroscopy of the CO stretching vibration is explored through vibrational line profile synthesis. Comparison is then made to previous investigations of CO line profiles on this surface and on amorphous solid water as reported in Taj et al. (2017, 2019a). A tentative conclusion is drawn that CO vibrationally promoted desorption from, and diffusion on, the amorphous silica surface may be responsible for the correspondingly short vibrational excited state lifetime of CO on that surface. The contrast with CO on amorphous solid water, where direct and rapid vibrational relaxation into the solid water phonon bath occurs, is highlighted. The consequences of this from the standpoint of CO deposition on grain surfaces are discussed.
Original languageEnglish
Pages (from-to)5806-5812
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Volume504
Issue number4
Early online date27 May 2021
DOIs
Publication statusPublished - Jul 2021

Keywords

  • Astrochemistry
  • Molecular processes
  • Solid state: refractory
  • Solid state: volatile

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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