Interaction of hydrogen with surfaces of silicates: Single crystal vs. amorphous

Jiao He, Paul Frank, Gianfranco Vidali

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

We have studied how the formation of molecular hydrogen on silicates at low temperature is influenced by surface morphology. At low temperature (<30 K), the formation of molecular hydrogen occurs chiefly through weak physical adsorption processes. Morphology then plays a role in facilitating or hindering the formation of molecular hydrogen. We studied the formation of molecular hydrogen on a single crystal forsterite and on thin films of amorphous silicate of general composition (FexMg(x-1))2SiO 4, 0 < x < 1. The samples were studied ex situ by Atom Force Microscopy (AFM), and in situ using Thermal Programmed Desorption (TPD). The data were analysed using a rate equation model. The main outcome of the experiments is that TPD features of HD desorbing from an amorphous silicate after its formation are much wider than the ones from a single crystal; correspondingly typical energy barriers for diffusion and desorption of H, H2 are larger as well. The results of our model can be used in chemical evolution codes of space environments, where both amorphous and crystalline silicates have been detected.

Original languageEnglish (US)
Pages (from-to)15803-15809
Number of pages7
JournalPhysical Chemistry Chemical Physics
Volume13
Issue number35
DOIs
StatePublished - Sep 21 2011

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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