Anomaly in the relaxation dynamics close to the surface plasmon resonanceG. Weick1, 2, 3, D. Weinmann1, G.-L. Ingold2 and R. A. Jalabert1
1 Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504 (CNRS-ULP) - 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France
2 Institut für Physik, Universität Augsburg - Universitätsstraße 1, D-86135 Augsburg, Germany
3 Fachbereich Physik, Freie Universität Berlin - Arnimallee 14, D-14195 Berlin, Germany
received 5 December 2006; accepted in final form 28 February 2007; published April 2007
published online 27 March 2007
We propose an explanation for the anomalous behaviour observed in the relaxation dynamics of the differential optical transmission of noble-metal nanoparticles. Using the temperature dependences of the position and the width of the surface plasmon resonance, we obtain a strong frequency dependence in the time evolution of the transmission close to the resonance. In particular, our approach accounts for the slowdown found below the plasmon frequency. This interpretation is independent of the presence of a nearby interband transition which has been invoked previously. We therefore argue that the anomaly should also appear for alkaline nano- particles.
78.67.-n - Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures.
73.20.Mf - Collective excitations (including excitons, polarons, plasmons and other charge-density excitations).
71.45.Gm - Exchange, correlation, dielectric and magnetic response functions, plasmons.
© Europhysics Letters Association 2007