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Experimental results on the formation of molecular hydrogen on amorphous silicate surfaces are presented 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 for polycrystalline silicates, demonstrating the importance of grain morphology. Using these barriers we evaluate the efficiency of molecular hydrogen formation on amorphous silicate grains under interstellar conditions. It is found that unlike polycrystalline silicates, amorphous silicate grains are efficient catalysts of H_2 formation in diffuse interstellar clouds.
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 m
The study of the formation of molecular hydrogen on low temperature surfaces is of interest both because it allows to explore elementary steps in the heterogeneous catalysis of a simple molecule and because of the applications in astrochemistry. Here
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
We report on the first results of experiments to measure the recombination rate of hydrogen on surfaces of astrophysical interest. Our measurements give lower values for the recombination efficiency (sticking probability S x probability of recombinat
We compute the rate of diffusive nuclear burning for hydrogen on the surface of a magnetar (Soft Gamma-Ray Repeater or Anomalous X-Ray Pulsar). We find that hydrogen at the photosphere will be burned on an extremely rapid timescale of hours to years,