STICKING of MOLECULES on NONPOROUS AMORPHOUS WATER ICE

Jiao He, Kinsuk Acharyya, Gianfranco Vidali

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Accurate modeling of physical and chemical processes in the interstellar medium (ISM) requires detailed knowledge of how atoms and molecules adsorb on dust grains. However, the sticking coefficient, a number between 0 and 1 that measures the first step in the interaction of a particle with a surface, is usually assumed in simulations of ISM environments to be either 0.5 or 1. Here we report on the determination of the sticking coefficient of H2, D2, N2, O2, CO, CH4, and CO2 on nonporous amorphous solid water. The sticking coefficient was measured over a wide range of surface temperatures using a highly collimated molecular beam. We showed that the standard way of measuring the sticking coefficient - the King-Wells method - leads to the underestimation of trapping events in which there is incomplete energy accommodation of the molecule on the surface. Surface scattering experiments with the use of a pulsed molecular beam are used instead to measure the sticking coefficient. Based on the values of the measured sticking coefficient, we suggest a useful general formula of the sticking coefficient as a function of grain temperature and molecule-surface binding energy. We use this formula in a simulation of ISM gas-grain chemistry to find the effect of sticking on the abundance of key molecules both on grains and in the gas phase.

Original languageEnglish (US)
Article number56
JournalAstrophysical Journal
Volume823
Issue number1
DOIs
StatePublished - May 20 2016

Fingerprint

coefficients
molecular beams
molecules
chemical process
gas
simulation
trapping
energy
surface temperature
scattering
dust
well
accommodation
modeling
binding energy
chemistry
vapor phases
experiment
temperature
water

Keywords

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

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

STICKING of MOLECULES on NONPOROUS AMORPHOUS WATER ICE. / He, Jiao; Acharyya, Kinsuk; Vidali, Gianfranco.

In: Astrophysical Journal, Vol. 823, No. 1, 56, 20.05.2016.

Research output: Contribution to journalArticle

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