Hartree-Fock-DFT cluster calculations of the Si(111)7 × 7:H system

Que, Jian-Zhong; Radny, Marian W.; Smith, P. V.

doi:10.1016/s0039-6028(97)00479-2

Cited by 7 publications

(1 citation statement)

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“…Physisorbed atoms are weakly bound to the surface and are mobile at low grain temperatures (Ghio et al 1980), whereas chemisorbed atoms are strongly bound to the surface and become mobile only at grain temperature of a few hundred K (Barlow & Silk 1976;Aronowitch & Chang 1980;Klose 1992;Fromherz et al 1993;Que et al 1997;Jeloaica & Sidis 1999;Cazaux & Tielens 2002. By considering these two types of interactions between the atoms and the surface, H 2 can possibly form for a wide range of temperatures.…”

Section: Introductionmentioning

confidence: 99%

Molecular Hydrogen formation on grain surfaces

Cazaux

Caselli

Tielens³

et al. 2005

J. Phys.: Conf. Ser.

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Abstract. 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 take into consideration the uncertainties on the characteristics of graphitic surfaces. We calculate the H2 formation efficiency with the Langmuir Hinshelwood and Eley Rideal mechanisms, and discuss the importance of these mechanisms for a wide range of grain and gas temperatures. We also develop a Monte Carlo simulation to calculate the H2 formation efficiency and compare the results to our rate equation models. Our results are the following: (1) Depending on the barrier againt chemisorption, we predict the efficiency of H2 formation for a wide range of grain and gas temperatures. (2) The Eley-Rideal mechanism has an impact on the H2 formation efficiency at high grain and gas temperatures. (3) The fact that we consider chemisorption in our model makes the rate equation and Monte Carlo approaches equivalent.

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