Search for a local effect in multiatom resonant core excitation in a surface species: Photoemission and photon-stimulated desorption from N2 on Ni(111)
| Autor: | Feulner P., Ecker M., Jakob P., Romberg R., Weimar R., Menzel D., Fohlisch A., Wurth W., Yang S.H., Fadley C.S., Larciprete R., Lizzit S., Kostov K.L., Tyuliev G. |
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| Rok vydání: | 2005 |
| Zdroj: | 71 (2005): 125409–[8]. info:cnr-pdr/source/autori:Feulner P., Ecker M., Jakob P., Romberg R., Weimar R., Menzel D., Fohlisch A., Wurth W., Yang S.H., Fadley C.S., Larciprete R., Lizzit S., Kostov K.L., Tyuliev G./titolo:Search for a local effect in multiatom resonant core excitation in a surface species: Photoemission and photon-stimulated desorption from N2 on Ni(111)/doi:/rivista:/anno:2005/pagina_da:125409/pagina_a:[8]/intervallo_pagine:125409–[8]/volume:71 |
| Popis: | We have investigated photoabsorption, N 1s photoelectron emission, and photon-stimulated desorption (PSD) of N+ ions, from N2 molecules perpendicularly chemisorbed on Ni(111) surfaces, in the energy range of the Ni 2p3?2,1?2 excitations. For this system, N 1s photoemission monitors single-core-hole production, whereas PSD of N+ is mainly due to excitation of multiply excited N 1s core-hole states. The amplitude variations of these two signals and the kinetic energy distributions (KEDs) of the N+ ions were recorded as functions of the photon energy. In addition, we measured the amplitude variations of PE and PSD as a function of the photon incidence angle, which was varied from grazing (7° with respect to the surface) to steeper angles (43° and 50° with respect to the surface). For grazing incidence, strong variations of both the photoelectron and the N+ signals with photon energy and angle of incidence were found in the Ni 2p region which are compatible with x-ray optical (dielectric) effects, one manifestation of multiatom resonant photoemission. The N+ KEDs, which are known to depend strongly on the nature of the electronic excitation responsible, did not change across the Ni 2p3?2 threshold, which excludes any type of state selectivity in the interatomic core-coupling effects observed. For N 1s photoemission, a first analysis of our data suggests a variation of the N 1s signal at the Ni 2p edges also for steeper angles of light incidence, of comparable magnitude to that at grazing incidence. However, more careful x-ray photoelectron spectroscopy experiments and the investigation of electronically stimulated desorption of neutral N2 molecules and N atoms reveal that these effects are due to a strong increase of beam damage when passing the Ni 2p edge; these effects could be reduced by rapidly scanning the sample under the beam. We thus conclude that for high angles of incidence most of the Ni 2p-related changes in our N 1s photoemission signal are due to beam damage. |
| Databáze: | OpenAIRE |
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