2002/07/01 by S. Cazaux, A. G. G. M. Tielens · 10 citations
Physics and Astronomy · #Advanced Chemical Physics Studies #Astro and Planetary Science #Astrophysics and Star Formation Studies #astro-ph
paper · pdf · doi:10.1086/342607
published as Astrophys.J. 575 (2002) L29-L32 · 4 pages, 1 figure
arxiv created 2002/07/01 · openalex publication_date 2002/08/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
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 surface, allows quantum mechanical diffusion as well as thermal hopping for absorbed H atoms, and has been benchmarked versus recent laboratory experiments on H 2 formation on silicate surfaces. The results show that H 2 formation on grain surfaces is efficient in the interstellar medium up to some 300 K. At low temperatures (≤100 K), H 2 formation is governed by the reaction of a physisorbed H with a chemisorbed H. At higher temperatures, H 2 formation proceeds through a reaction between two chemisorbed H atoms. We present simple analytical expressions for H 2 formation that can be adopted to a wide variety of surfaces once their surface characteristics have been determined experimentally.