Osnabrück 2002 – wissenschaftliches Programm
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MO: Molekülphysik
MO 13: Cluster V (gemeinsam mit Fachverband Atomphysik)
MO 13.1: Vortrag
Donnerstag, 7. März 2002, 14:00–14:15, HS 01/E01
Oscillations in the photoelectron yield of C70 — •Burkhard Langer1, Antony Wills2, Georg Prümper2, Rainer Hentges2, and Uwe Becker2 — 1Max-Born-Institut Berlin, Max-Born-Str. 2A, 12489 Berlin, Germany — 2Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
Fullerenes, in particular C60 and C70, are a very specific form of matter causing unexpected behavior even in such matured fields as photoelectron emission. In recent years it has been shown that the partial photoemission cross sections of the two outermost valence shells of C60 show strong oscillations due to the potential in which the corresponding electrons are bound. The frequency of the oscillation is related to the avarage radius of the fullerene molecule, which is for the case of C60 the bucky ball radius. In the case of C70 which has a more egg like shape the average radius of the rotating molecule should cause the oscillating behavior. Former measurements of C70 were not performed at sufficiently close energy intervals in order to prove this assumption. Therefore, a new photoemission experiment of C70 was performed at the beamline BW3 of HASYLAB and the new MBI-Beamline at BESSY II measuring the ratio of the cross sections of the outermost C70 photolines between 40 and 200 eV. The data were fitted by exponentially decaying spherical Bessel functions. The result of such a fit gives the mean radius R of the rotating C70 molecule. The value is in good agreement with what one would expect from averaging over all three axis of the ellipsoidally shaped fullerene. This corroborates the simple quantum oscillation model used to explain the partial cross section oscillation in fullerenes.