Thermal desorption of water ice in the interstellar medium

Fraser, Helen J. and Collings, Mark P. and McCoustra, Martin R.S. and Williams, David A. (2001) Thermal desorption of water ice in the interstellar medium. Monthly Notices of the Royal Astronomical Society, 327 (4). pp. 1165-1172. ISSN 0035-8711

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    Abstract

    Water (H2O) ice is an important solid constituent of many astrophysical environments. To comprehend the role of such ices in the chemistry and evolution of dense molecular clouds and comets, it is necessary to understand the freeze-out, potential surface reactivity, and desorption mechanisms of such molecular systems. Consequently, there is a real need from within the astronomical modelling community for accurate empirical molecular data pertaining to these processes. Here we give the first results of a laboratory programme to provide such data. Measurements of the thermal desorption of H2O ice, under interstellar conditions, are presented. For ice deposited under condi- tions that realistically mimic those in a dense molecular cloud, the thermal desorption of thin films (50 molecular layers) is found to occur with zero order kinetics charac- terised by a surface binding energy, Edes, of 5773 ±60 K, and a pre-exponential factor, A, of 1030±2 molecules cm−2 s−1. These results imply that, in the dense interstellar medium, thermal desorption of H2O ice will occur at significantly higher temperatures than has previously been assumed.

    • Item type:Article
      ID code:2914
      Dates:
      Date
      Event
      7 November 2001
      Published
      Keywords:molecular data, molecular processes, methods, laboratory, ISM, molecules, nanoscience, Astronomy, Astronomy and Astrophysics, Space and Planetary Science
      Subjects:Science > Astronomy
      Department:Faculty of Science > Physics
      Depositing user: Strathprints Administrator
      Date deposited:15 Feb 2007
      Last modified:23 Sep 2021 03:28
      Related URLs:
      URI:https://strathprints.strath.ac.uk/id/eprint/2914
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