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Title: Dynamics of CO in amorphous water-ice environments

The long-timescale behavior of adsorbed carbon monoxide on the surface of amorphous water ice is studied under dense cloud conditions by means of off-lattice, on-the-fly, kinetic Monte Carlo simulations. It is found that the CO mobility is strongly influenced by the morphology of the ice substrate. Nanopores on the surface provide strong binding sites, which can effectively immobilize the adsorbates at low coverage. As the coverage increases, these strong binding sites are gradually occupied leaving a number of admolecules with the ability to diffuse over the surface. Binding energies and the energy barrier for diffusion are extracted for various coverages. Additionally, the mobility of CO is determined from isothermal desorption experiments. Reasonable agreement on the diffusivity of CO is found with the simulations. Analysis of the 2152 cm{sup –1} polar CO band supports the computational findings that the pores in the water ice provide the strongest binding sites and dominate diffusion at low temperatures.
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4]
  1. Theoretical Chemistry, Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands)
  2. Gorlaeus Laboratories, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden (Netherlands)
  3. Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States)
  4. Division of Geological and Planetary Science, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States)
Publication Date:
OSTI Identifier:
22348188
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 781; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMORPHOUS STATE; BINDING ENERGY; CARBON MONOXIDE; COMPUTERIZED SIMULATION; DESORPTION; DIFFUSION BARRIERS; ICE; MOBILITY; MONTE CARLO METHOD; POROUS MATERIALS; SUBSTRATES; SURFACES; WATER