Alkali sensitization of H+ electron stimulated desorption from H adsorbed on Ni(111)

• Published in: The Journal of chemical physics 1988-07, Vol.89 (1), p.570-576
• Main Authors: LANZILLOTTO, A.-M, DRESSER, M. J, ALVEY, M. D, YATES, J. T. JR
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemistry; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; General and physical chemistry; Materials science; Metals, semimetals and alloys; Metals. Metallurgy; Physics; Solid-gas interface; Specific materials; Surface physical chemistry
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.455447

It is shown that alkali adatoms coadsorbed in the presence of adsorbed hydrogen on Ni(111) can cause a large increase in the cross section for H+ emission during electron stimulated desorption. This phenomenon was investigated using the digital ESDIAD (electron stimulated desorption ion angular distribution) technique as well as by temperature programmed desorption (TPD). H+ ions produced by electron impact on alkali–hydrogen complexes are ejected in sharp normally oriented ion angular distributions. The sensitization of the H(a)→e−H+ process occurs with Li, Na, and K but not as strongly with Rb and Cs. Attractive interactions exist in the adsorbed layer between the hydrogen and the alkali adatoms. A model is discussed involving the formation of ‘‘alkali–hydride-like’’ surface complexes, with Hδ− located on top of alkali atom sites.