Chemisorption on perfect surfaces: Hydrogen and nitrogen on tungsten and rhodium

• Published in: The Journal of chemical physics 1979-01, Vol.71 (1), p.259-270
• Main Authors: Polizzotti, R. S., Ehrlich, Gert
• Format: Article
• Language: English
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.438066

Chemisorption on highly perfect low index surfaces, prepared by low temperature field evaporation, is compared in simultaneous field emission measurements with chemisorption on the atomically rough regions which dominate the total electron current from the emitter. For the (110) plane of tungsten, the most densely packed of this lattice, it is found that contrary to some earlier reports, nitrogen does chemisorb after high exposures at room temperature. The nitrogen has no significant effect upon the work function for electrons; instead, chemisorption manifests itself by a change in the absolute emission intensity. Hydrogen also chemisorbs on W(110). However, at T?144 °K, this plane is populated only after the rougher, stepped regions have been substantially covered by a chemisorbed layer. At still lower temperatures, at T?38 °K, a layer of molecularly bound gas forms on exposure of W(110) to hydrogen. The layer is removed by warming to T