Eur. Phys. J. D 24, 111-114 (2003)
https://doi.org/10.1140/epjd/e2003-00156-y

Optical properties of mixed clusters: comparative study of Ni/Ag and Pt/Ag clusters

¹ Laboratoire de Spectrométrie Ionique et Moléculaire, CNRS and Université Lyon I, bâtiment Kastler, 43 boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France
² Département de Physique des Matériaux, CNRS and Université Lyon I, bâtiment Brillouin, 43 boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France
³ Institut de Recherche sur la Catalyse, CNRS, 2 avenue Albert Einstein, 69626 Villeurbanne Cedex, France

Corresponding author: ^a cottanci@lasim.univ-lyon1.fr

Received: 10 September 2002
Published online: 3 July 2003

Abstract

The optical properties of mixed (Ni_0.5Ag_0.5)_n and Pt/Ag clusters are investigated in the size range  nm. Low Energy Ion Spectroscopy (LEIS) experiments show that the cluster surface is entirely covered by silver atoms for the two systems. The optical spectra of Ni/Ag clusters exhibit a large Surface Plasmon Resonance (SPR), damped and widened when the cluster size decreases, in agreement with a classical model assuming a core-shell geometry and including the reduction of the conduction electron mean-free path in the silver shell. For Pt/Ag clusters, no SPR emerges in the size range  nm, although it is predicted within a classical model, a pronounced SPR appearing only for clusters larger than 10 nm in diameter.