Efficiency of Molecular Hydrogen Formation on Silicates
نویسندگان
چکیده
منابع مشابه
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 interstellar medium. On the basis of our experimental evidence, we recognize that there are two main regimes of H coverage that are of astrophysical importance; for each of them we provide an expressi...
متن کاملMolecular 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 relevant diffusion and desorption processes are obtained. They turn out to be significantly higher than those obtained earlier for polycrystalline silicates, demonstrating the importance of grain morphol...
متن کاملMolecular Hydrogen Formation on Porous Dust Grains
Recent laboratory experiments on interstellar dust analogues have shown that H2 formation on dust grain surfaces is efficient in a range of grain temperatures below 20 K. These results indicate that surface processes may account for the observed H2 abundance in cold diffuse and dense clouds. However, high abundances of H2 have also been observed in warmer clouds, including photon-dominated regi...
متن کاملMolecular Hydrogen formation on grain surfaces
We reconsider H2 formation on grain surfaces. We develop a rate equation model which takes into account the presence of both physisorbed and chemisorbed sites on the surface, including quantum mechanical tunnelling and thermal diffusion. In this study, we took into consideration the uncertainties on the characteristics of graphitic surfaces. We calculate the H2 formation efficiency with the Lan...
متن کاملMolecular 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 rate equations. The parameters of the rate equation model are fitted to temperature-programmed desorption curves obtained in the laboratory. These parameters are the activation energy barriers for ato...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 1997
ISSN: 0004-637X
DOI: 10.1086/310746