Molecular Hydrogen Formation on Ice Under Interstellar Conditions

  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},
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
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
The sticking of atomic hydrogen on amorphous water ice
Using classical molecular dynamics, we have simulated the sticking and scattering process of a hydrogen atom on an amorphous ice film to predict the sticking probability of hydrogen on ice surfaces.
Some fundamental properties and reactions of ice surfaces at low temperatures.
The static and dynamic properties of an ice surface as a reaction medium, such as its structure, molecule diffusion and proton transfer dynamics, and the surface preference of hydronium and hydroxide ions, are discussed in relation to the reactivity of the surface.
Changes in the morphology of interstellar ice analogues after hydrogen atom exposure.
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
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
Hydrogen (H) atom diffusion on dust grain surfaces is the rate-limiting step in many hydrogenation reactions taking place in interstellar clouds. In cold (10–30 K) molecular clouds, the dust grains
Interaction of atomic and molecular deuterium with a nonporous amorphous water ice surface between 8 and 30 K.
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.


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
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.
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
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Master Equation for Hydrogen Recombination on Grain Surfaces
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Formation of molecular hydrogen on analogues of interstellar dust grains: experiments and modelling
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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