Eur. Phys. J. D 4, 95-108 (1998)
https://doi.org/10.1007/s100530050189

Optical properties of gold metal clusters: A time-dependent local-density-approximation investigation

¹ Laboratoire de Spectrométrie Ionique et Moléculaire, CNRS and Université Lyon I, Btiment 203, 43 boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France
² Département de Physique des Matériaux, CNRS and Université Lyon I, Btiment 203, 43 boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France

Corresponding author: ^a lerme@hplasim2.univ-lyon1.fr

Received: 9 March 1998
Revised: 5 June 1998
Accepted: 3 July 1998
Published online: 15 October 1998

Abstract

The optical response of free and matrix-embedded gold metal clusters Au_N is investigated in the framework of the time-dependent local-density-approximation (TDLDA). The characteristics of the surface plasmon resonance are carefully analyzed as a function of the model parameters and the particle radius. The strong influence of the frequency-dependence of the 5d core-electron dielectric function in the vicinity of the interband threshold is emphasized. The size evolution of the Mie-frequency in free gold clusters exhibits a noticeable blue-shift trend as the particle size decreases, much stronger than in silver clusters. The width and shape of the resonance, essentially ruled by the decay via the interband transitions, are found closely correlated to the imaginary component of the core-electron dielectric function. In presence of a surrounding matrix the blue-shift trend is largely rubbed out. Agreement with recent experimental results on size-selected gold clusters embedded in an alumina matrix may be achieved by taking into account the porosity effects at the metal/matrix interface. The comparison with the predictions of classical models is also provided.