Berlin 2001 – wissenschaftliches Programm
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A: Atomphysik
A 18: Photoionisation II (joint session A and MO)
A 18.3: Vortrag
Freitag, 6. April 2001, 16:15–16:30, H1012
Time resolved two-photon photoelectron spectroscopy on small transition metal clusters: studies on the relaxation dynamics of optically excited states — •N. Pontius, G. Lüttgens, P.S. Bechthold, M. Neeb, and W. Eberhardt — Forschungszentrum Jülich GmbH
Optically excited states in small clusters and molecules are usually long-lived compared with the time scale on which atomic movement occurs. Thus, a coherent excitation of these small systems allows the observation of atomic motion and rearrangement. In contrast, excited electrons in metals relax extremely fast via inelastic electron-electron interaction (≪ 100 fs) which is favored by the comparatively large and continuous density of states around the Fermi edge. Recently it could be shown that even small transition metal clusters as Pt3− and Pd3− reveal fast electronic relaxations [1,2,3]. In these clusters the density of states is enlarged by the contribution of a multitude of d-derived orbitals, which cross the Fermi level. In order to study the relaxation processes in such small metallic systems systematically the time resolved photoelectron studies have been extended on Pd4− and Pd7−.
[1] N. Pontius, P.S. Bechthold, M. Neeb, W. Eberhardt: Phys. Rev. Lett. 84, 1132 (2000).
[2] N. Pontius, P.S. Bechthold, M. Neeb, W. Eberhardt: Appl. Phys. B 71, 351 (2000).
[3] N. Pontius, P.S. Bechthold, M. Neeb, W. Eberhardt: J. Electron Spectrosc. Relat. Phenom. (2001), in press.