Dresden 2011 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 27: Nano Plasmonic (with HL)
A 27.5: Hauptvortrag
Freitag, 18. März 2011, 12:30–13:00, BAR 205
Appearance of Surface and Volume Plasmons in Fullerenes — •Sanja Korica1, Axel Reinköster1, Markus Braune1, Jens Viefhaus1, Daniel Rolles1, G. Fronzoni2, D. Toffoli2, M. Stener2, P. Decleva2, O. Al-Dossary3, Burkhard Langer4, and Uwe Becker1,3 — 1Fritz-Haber-Institut der MPG, Berlin — 2Universitá di Trieste, Italy — 3King Saud University, Riyadh, Saudi-Arabia — 4Freie Universität Berlin
Since the discovery of the C60 molecule in 1985 many studies have been performed to investigate its fundamental properties. These properties are mainly driven by its unique molecular structure like its spherical shell. One of the important characteristics of this molecule is the collective response of its valence electron cloud to electromagnetic radiation. This collective behavior gives rise to the occurrence of the giant dipole resonance a surface plasmon in the absorption spectrum centered around 20 eV, which has been analyzed theoretically by various authors. In addition, our photoionization cross-section measurements reveal a resonance near 40 eV, a volume plasmon analogous to observations made for C60 ions. Time-dependent density functional calculations confirm the collective nature of this feature as corresponding plasmon excitation. A third excitation of this kind is predicted but not experimentally confirmed. Concerning photoelectron emission, plasmonic excitations are characterized by a particular intensity behavior near threshold. They follow the threshold behavior law predicted for the first time by Thomas Derrah. Our measurements of the C60 plasmon excitations above the C 1s ionization threshold confirm this law very well and are in unexpectedly good agreement with the corresponding behavior of K-shell satellite excitations in atoms such as neon.