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Metastable-atom desorption and luminescence stimulated by low-energy electron impact on condensed Kr, Xe, and Xe/Kr films

Mann A., Leclerc G., Sanche L.. 1992. Physical review B. Condensed matter A, 46 (15) : p. 9683-9690.

DOI: 10.1103/PhysRevB.46.9683

Metastable-atom desorption and uv luminescence from thin films of Kr and Xe on Pt(111) stimulated by impact of monochromatic low-energy electrons (E=5-25 eV, ?E=60 meV) have been studied. For either pure rare-gas film, the excitation function of the total luminescence signal shows two broad peaks that are presumably related to the interplay between creation of excitons and free-electron-hole pairs. Metastable-particle desorption is very weak for pure Kr and not detectable for pure Xe over the entire range of electron energies. However, for 35-ML Kr films covered with 1-ML Xe (ML denotes monolayer), a considerable signal due to metastable-particle desorption is observed. The energy dependence of the signal in the 8-12.6-eV region leads to an interpretation of the desorption in the form of two different mechanisms with different thresholds. The first one is based on the creation of a Xe exciton in a Kr environment, while in the second scheme the excitation energy is transferred from a Kr bulk exciton to a Xe atom at the Kr-Xe interface. In both cases, repulsive Kr-Xe* interaction near the film surface is postulated to eject a metastable Xe* atom.

Mots-clés : luminescence; rayonnement ultraviolet; désorption; film

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