Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 8: Electron and spin dynamics
O 8.8: Vortrag
Montag, 26. März 2012, 12:15–12:30, A 060
Trapping of image-potential resonances on free-electron-like metal surface — •Ulrich Höfer1,2, Matthias Winter1, Eugene V. Chulkov2, and Pedro M. Echenique2 — 1Fachbereich Physik, Philipps-Universität Marburg, Germany — 2Donostia International Physics Center (DIPC), San Sebastián, Spain
Image-potential states have been studied by two-photon photoemission (2PPE) for the surface of Al(100) where the whole series is energetically degenerate with free-electron-like bulk states. In contrast to expectations, the series of resonances is not smeared out to one broad structure as a result of a strong coupling to the bulk continuum. Instead, the first resonance (n=1) is found to be suppressed and the resonances with quantum numbers n=2,3,4,5 are resolved as individual peaks in the time-resolved spectra. Both effects are suggested to be a consequence of resonance trapping [1].
Here, we combine the multiple scattering approach to describe surface states with an open quantum system formalism that properly takes into account strong coupling of resonances to a continuum. The theory is able to quantitatively describe trapping of adjacent surface resonances for simple metals.
[1] M. Winter, E. V. Chulkov, U. Höfer, PRL 107, 236801 (2011)