Molecular Hydrogen Formation on Ice Under Interstellar Conditions

@article{Perets2004MolecularHF,
  title={Molecular Hydrogen Formation on Ice Under Interstellar Conditions},
  author={Hagai B. Perets and Ofer Biham and Giulio Manic{\'o} and Valerio Pirronello and Joseph E. Roser and Sol Swords and Gianfranco Vidali},
  journal={The Astrophysical Journal},
  year={2004},
  volume={627},
  pages={850-860}
}
The results of experiments on the formation of molecular hydrogen on low-density and high-density amorphous ice surfaces are analyzed using a rate equation model. The activation energy barriers for the relevant diffusion and desorption processes are obtained. The more porous morphology of the low-density ice gives rise to a broader spectrum of energy barriers compared to the high-density ice. Inserting these parameters into the rate equation model under steady-state conditions, we evaluate the… 
Molecular Hydrogen Formation on Amorphous Silicates under Interstellar Conditions
Experimental results on the formation of molecular hydrogen on amorphous silicate surfaces are presented for the first time and analyzed using a rate equation model. The energy barriers for the
Structural effects of ice grain surfaces on the hydrogenation of CO at low temperatures
Experiments on the hydrogenation of CO on crystalline and amorphous ice at 15 K were carried out to investigate the structural effects of the ice surface. The effective rate of H atom addition to CO
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Some fundamental properties and reactions of ice surfaces at low temperatures.
TLDR
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Changes in the morphology of interstellar ice analogues after hydrogen atom exposure.
TLDR
There is an exponential decrease in the porosity of the amorphous water ice sample following D-atom irradiation, and this effect is likely to be efficient and, together with other compaction processes, provides a good argument to believe that interstellar ice is amorphously and non-porous.
Diffusion-desorption ratio of adsorbed CO and CO2 on water ice (Research Note)
Context. Di usion of atoms and molecules is a key process for the chemical evolution in star-forming regions of the interstellar medium. Accurate data on the mobility of many important interstellar
Molecular hydrogen desorption from amorphous surfaces at low temperature.
  • G. Vidali, L. Li
  • Chemistry, Medicine
    Journal of physics. Condensed matter : an Institute of Physics journal
  • 2010
TLDR
From molecular desorption data, the energy distribution of binding sites using a direct inversion method is derived and the application of this type of data to the study of elementary processes of migration of atoms and molecules on and ejection from disordered surfaces at low temperature is discussed.
Long-Time Scale Simulations of Tunneling-Assisted Diffusion of Hydrogen on Ice Surfaces at Low Temperature
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Interaction of atomic and molecular deuterium with a nonporous amorphous water ice surface between 8 and 30 K.
TLDR
An upper limit to the value of the atom adsorption energy E(a) approximately 29 meV is estimated, in agreement with previous calculations, to be found on porous water ice surfaces between 8 and 30 K.
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References

SHOWING 1-10 OF 38 REFERENCES
Molecular hydrogen formation on astrophysically relevant surfaces
Recent experimental results about the formation of molecular hydrogen on astrophysically relevant surfaces under conditions close to those encountered in the interstellar medium are analyzed using
Importance of Surface Morphology in Interstellar H2 Formation
TLDR
Results suggest that grain morphology, rather than the detailed chemical nature of the grain surface, is most important in determining the energy content of the H2 as it is released from the grain into the interstellar medium.
LABORATORY MEASUREMENTS OF MOLECULAR HYDROGEN FORMATION ON AMORPHOUS WATER ICE
We report on an experimental study of the formation of hydrogen molecules by surface recombination of adsorbed H atoms on amorphous water ice under conditions closely simulating those encountered in
Molecular hydrogen formation in the interstellar medium
We have developed a model for molecular hydrogen formation under astrophysically relevant conditions. This model takes fully into account the presence of both physisorbed and chemisorbed sites on the
Efficiency of Molecular Hydrogen Formation on Silicates
We report on laboratory measurements of molecular hydrogen formation and recombination on an olivine slab as a function of surface temperature under conditions relevant to those encountered in the
Formation of Molecular Hydrogen on Amorphous Water Ice
In this paper, we report on the formation of molecular hydrogen on different types of amorphous water ice. We show that mass spectra of desorbing molecules upon formation are sensitive to the way in
Master Equation for Hydrogen Recombination on Grain Surfaces
Recent experimental results on the formation of molecular hydrogen on astrophysically relevant surfaces under conditions similar to those encountered in the interstellar medium provided useful
Formation of molecular hydrogen on analogues of interstellar dust grains: experiments and modelling
Molecular hydrogen has an important role in the early stages of star formation as well as in the production of many other molecules that have been detected in the interstellar medium. In this review
Measurement of the Kinetic Energy of Hydrogen Molecules Desorbing from Amorphous Water Ice
A hydrogen molecule that is formed on an interstellar grain might retain some of the 4.48 eV of energy that is released in the recombination reaction of two hydrogen atoms. We set up an experiment to
High-Density Amorphous Ice, the Frost on Interstellar Grains
Most water ice in the universe is in a form which does not occur naturally on Earth and of which only minimal amounts have been made in the laboratory. We have encountered this 'high-density
...
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