Ethylene Adsorption on Pt(111)

Abstract

The scattering of helium and deuterium beams has been used along with LEED to establish the cleanliness and order of a Pt surface under ultrahigh‐vacuum conditions and to study the adsorption of ethylene on the (111) face. Ethylene adsorbs irreversibly according to first‐order Langmuir kinetics with a sticking coefficient of unity, and dissociates upon adsorption into an acetylenic species which occupies four platinum sites and two mobile hydrogen atoms. At high coverages the ethylene is ordered, producing a (2 × 2) LEED pattern. Above temperatures of 200°C irreversible degradation of the adsorbate occurs. The use of both atomic scattering and LEED seems to be uniquely complimentary for the study of adsorption on clean surfaces of single crystals.