A theoretical study of hydrogen diffraction following photodissociation of adsorbed molecules

Ronnie Kosloff*, Yehuda Zeiri

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

A new probe of surface structure is presented which is based on the photodissociation of hydrogen from an adsorbate molecule. The event creates an atomic hydrogen fragment, positioned between the adsorbate layer and the solid surface. Due to its light mass, the hydrogen dynamics is quantum mechanical in nature. A useful image is of the hydrogenic wave function behaving like a liquid able to fill all cracks. The coherent character of the hydrogenic wave function is crucial in the ability of the photodissociation experiment to act as a probe. A series of case studies has been carried out whose aim is to reveal the relation between the structure of the surface and the asymptotic energy resolved angular distribution of the hydrogen fragment. The dynamics of the hydrogen atom motion was modeled by the time dependent Schrödinger equation. The cases studied include the dissociation of a single HBr adsorbate on flat and corrugated surfaces. A broad specular peak was observed, in addition to diffraction peaks which can be correlated with the corrugation. Moreover, selective adsorption peaks, which can be correlated with the attractive part of the surface potential, have been identified. Systems in which the hydrogenic wave function scatters from several adsorbates were also investigated. It was found that the scattering is dominated by the trapping of the wave function by unstable periodic orbits. The quantization rules of these periodic orbits have been identified, creating a link between the structure of the adsorbates and the asymptotic angular distributions.

Original languageEnglish
Pages (from-to)1719-1733
Number of pages15
JournalThe Journal of Chemical Physics
Volume97
Issue number3
DOIs
StatePublished - 1992

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