Dresden 2006 – wissenschaftliches Programm
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SYET: Dynamics of electron transfer processes at surfaces
SYET 1: Dynamics of electron transfer processes at surfaces
SYET 1.5: Hauptvortrag
Donnerstag, 30. März 2006, 12:00–12:30, HSZ 04
Damping of the surface plasmon resonance in metal nanoparticles: mechanisms operating on the femtosecond timescale — •F. Hubenthal, C. Hendrich, and F. Träger — Universität Kassel, Institut für Physik und Center for Interdisciplinary Nanostructure Science and Technology, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
We present systematic measurements of the ultrafast dephasing time T2 of surface plasmon excitations in gold and silver nanoparticles (NPs) with the objective to identify the involved damping mechanisms. Au and Ag NPs were produced by applying two laser-based methods [1]. Subsequently, systematic measurements of T2 in the size range between R = 2 nm and 23 nm were carried out by persistent spectral hole burning [2] as a function of all relevant parameters, i.e. particle size and shape, substrate material and adsorbate coverage. The most essential among the numerous results is the observation of the influence of the reduced dimension on the dephasing time. While T2 = 14 fs has been measured for Au NPs with radii larger than 12 nm which is consistent with the damping contained in the bulk dielectric function, the value of T2 shrinks to, for example, 5 fs for R = 3 nm. This cannot be explained semiclassically by taking only the surface scattering of the oscillating electrons into account. In fact, we observe an increased Landau damping in Au NPs. It is identified by comparing our experimental results for Au and Ag NPs to theoretical predictions of Persson and Yannouleas et al.
[1] T. Wenzel, J. Bosbach, A. Goldmann, F. Stietz, F. Träger, Appl. Phys. B 69, 513 (1999) [2] J. Bosbach, C. Hendrich, F. Stietz, T. Vartanyan, F. Träger, Phys. Rev. Lett. 89, 257404 (2002)