Hamburg 2001 – wissenschaftliches Programm

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O: Oberflächenphysik

O 34: Teilchen und Cluster (II)

O 34.13: Vortrag

Donnerstag, 29. März 2001, 18:30–18:45, K

Measurement of the surface plasmon dephasing time with the spectral hole burning technique: theoretical considerations — •Tigran Vartanyan, Frank Stietz, and Frank Träger — Experimentalphysik I, Universität Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel

Hole burning is a well established technique used for the elimination of inhomogeneous broadening. Still, its application to systems with intrinsic life times in the femtosecond range seems to be rather difficult. Recently this was in fact accomplished in a measurement of the surface plasmon dephasing time of supported metal clusters due to the enhanced selectivity of the depopulation mechanism. It relies on thermally activated evaporation followed by shrinking and reshaping of laser heated metal clusters. Although this mechanism resembles photochemical hole burning it exhibits also unique features, most notably, it does not suffer from a convolution of the homogeneous linewidth with the width of the hole burnt into the frequency distribution. Hence, contrary to the usual case, the width of the spectral hole is not doubled. This is of crucial importance as the ratio of inhomogeneous broadening resulting from the nanoparticle size and shape distribution to the homogeneous width of the plasmon is only about three. We present a detailed theoretical account of this novel technique, which makes possible the precise determination of the plasmon lifetime in the range of only few femtoseconds.