Münster 1997 – wissenschaftliches Programm
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O: Oberflächenphysik
O 8: Elektronische Struktur I
O 8.8: Vortrag
Montag, 17. März 1997, 17:45–18:00, S 1
The surface photoeffect induced by alkali metal layers on Al(111) — •S.R. Barman1, Y. Cai1, K. Horn1, V. Ibanez2, and P. H"aberle2 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin — 2Universidad Tecnica Federico Santa Maria, Valparaiso, Chile
The spatially varying photon field at a metal surface can strongly affect the magnitude and photon energy dependence of photoemission from a metal. The frequency dependence of this effect strongly depends on the effective charge density distribution of the metal surface. Here we report angle- and energy-resolved photoyield measurements from clean and alkali metal-covered Al(111) surfaces. We find that for increasing alkali metal thickness, a suppression of the Al multipole plasmon mode and an increase in alkali-related threshold emission occur. Beyond a monolayer, intense signatures of the alkali metal bulk and multipole plasmon are observed. A particularly interesting observation is the response of the alkali metal/Al(111) surface alloys such as the Al(111)-(2 x 2)Na, since it depends on the distribution of the reduced charge density at the surface. These data are discussed in relation to recent TDLDA calculations [1], and good agreement is found.
[1] A.Liebsch, Phys.Rev.Lett. 67, 2858(1992); H.Ishida and A.Liebsch, Phys.Rev. B 45, 6171(1992).