Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 4: Elektronische Struktur I
O 4.7: Vortrag
Montag, 24. März 2003, 12:45–13:00, FOE/ANOR
Modified core exciton absorption at the 1D circumference of physisorbed Ar islands — •Markus Heßler1,2, Kai Fauth1,2, and Gisela Schütz2 — 1Physikalisches Institut, Universität Würzburg, Am Hubland, 97074-Würzburg — 2MPI für Metallforschung, Heisenbergstraße 1, 70569 Stuttgart
We have studied the evolution of the 2p absorption spectra of Ar
physisorbed on graphite (HOPG) as a function of coverage.
At coverages below ≈ 0.1 ML a shoulder appears in the excitonic
regime, shifted to smaller excitation energies. Its absorption energy is
thus intermediate between the monolayer and the atomic gas phase exciton
energies [1]. The relative weight
of the low energy feature scales roughly as √θ, where θ
is the coverage. We identify this absorption as being due to the
circumferential atoms of 2D Ar islands. This observation fits well to the
established scenario of spatial confinement of the excited state wave
function. We compare our
data to measurements recorded with gas phase clusters [2].
The fully modulated solid state NEXAFS at higher energies is only observed
in annealed multilayers.
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