Binding energy of molecules on water ice: Laboratory measurements and modeling

Jiao He, Kinsuk Acharyya, Gianfranco Vidali

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

We measured the binding energy of N2, CO, O2, CH4, and CO2 on non-porous (compact) amorphous solid water (np-ASW), of N2 and CO on porous ASW, and of NH3 on crystalline water ice. We were able to measure binding energies down to a fraction of 1% of a layer, thus making these measurements more appropriate for astrochemistry than the existing values. We found that CO2 forms clusters on the np-ASW surface even at very low coverages. The binding energies of N2, CO, O2, and CH4 decrease with coverage in the submonolayer regime. Their values at the low coverage limit are much higher than what is commonly used in gas-grain models. An empirical formula was used to describe the coverage dependence of the binding energies. We used the newly determined binding energy distributions in a simulation of gas-grain chemistry for cold cloud and hot-core models. We found that owing to the higher value of binding energy in the submonolayer regime, a fraction of all these ices remains for much longer and up to higher temperatures on the grain surface compared to the single value energies currently used in the astrochemical models.

Original languageEnglish (US)
Article number89
JournalAstrophysical Journal
Volume825
Issue number2
DOIs
StatePublished - Jul 10 2016

Keywords

  • ISM: abundances
  • ISM: atoms
  • ISM: molecules
  • astrochemistry
  • dust, extinction

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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