Hannover 2003 – wissenschaftliches Programm

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A: Atomphysik

A 13: Cluster und Potentialstreuung

A 13.2: Vortrag

Donnerstag, 27. März 2003, 11:15–11:30, F128

Photoelectron Spectroscopy of Neutral Silver Clusters — •Paul Radcliffe, Andreas Przystawik, Thomas Diederich, Tilo Döppner, Josef Tiggesbäumker und Karl-Heinz Meiwes-Broer — Fachbereich Physik, Uni Rostock, 18051 Rostock

Neutral silver clusters Ag_N (N = 2..100) are grown in liquid helium droplets with a temperature of 0.4 K. For the Ag₈- cluster a strong absorption resonance was found in the ultraviolet by applying resonant two photon ionization [1,2]. Making use of this resonant intermediate state we measure first photoelectron spectra of the neutral silver octamer, giving an upper limit for the ionization potential (IP) of 6.90 eV. Varying the laser excitation energy over the width of the resonance shows a shift in the calculated IP threshold. This suggests that direct two photon ionization is hindered by rapid relaxation, via intramolecular vibrational relaxation (IVR), within a few 100 ps to a longer living intermediate state.

[1] Th. Diederich, J. Tiggesbäumker, K.H. Meiwes-Broer, J. Chem. Phys. 116, 3263 (2002)

[2] F. Federmann, K. Hoffmann, N. Quaas, J. P. Toennies, Eur. Phys. J. D. 9, 11 (1998)