International audienc

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In this paper the specific properties of free clusters and the formation of new cluster-assembled materials using the low energy cluster beam deposition (LECBD) technique are discussed. Recent results obtained for free clusters are summarized with special attention to new observed structures. As for the specific structures and properties of cluster-assembled materials, two main aspects are specially emphasized: the memory effect of the free cluster properties leading to the formation of new phases and the effect of the specific nanostructure of the cluster-assembled materials related to the random cluster stacking mechanism characteristic of the LECBD. These effects and the corresponding potential applications are illustrated using some selected examples: new diamond-like carbon films produced by fullerene depositions (memory effect) and grain effect on the magnetic properties of cluster-assembled transition metal films.

We have studied the spectral response of individual pairs of gold nanoparticles chemically synthesized and stabilized on a transparent thin film. Very thin interspacing distances are explored by taking advantage of a residual layer of surfactant molecules at the metal surface. Absolute extinction cross section measurements by the spatial modulation spectroscopy technique are correlated to the corresponding high magnification images independently obtained from transmission electron microscopy. The signature of a transition from isolated to conductively coupled particles is evidenced in the optical spectra and is discussed in relation with their morphology. The strength of the electromagnetic coupling is controlled not only by their spacing but also by the shape of their opposite surfaces in the gap region.