N. Kébaïli

Curvature effect on the interaction between folded graphitic surface and silver clusters

Evidence of curvature effects on the interaction and binding of silver clusters on folded graphitic surfaces has been shown from both experiment and theory. Density Functional Theory (DFT) calculations within the local density and generalized gradient approximations have been performed for the structural relaxation of both Ag and Ag

Enhancement of Ag cluster mobility on Ag surfaces by chloridation

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Collective Optical Excitation in Free Metal Clusters

on curved surfaces, showing a cross-over from quantum to classical behaviour. Using Lennard-Jones potential to model the interaction between a single cluster and the graphene surface, evidence is found for the curvature effect on the binding of silver nano-particles to folding graphitic surfaces. The theoretical results are compared to SEM and AFM images of samples obtained from pre-formed silver cluster deposition on carboneous substrates exhibiting anisotropic pleat structures.

Coarsening and pearling instabilities in silver nanofractal aggregates

To understand the role of chlorine in the stability and the observed fragmentation of Ag dendritic nanostructures, we have studied computationally two model systems using density functional theory. The first one relates to diffusion of Ag(n) and Ag(n)Cl(m) (n = 1-4) clusters on an Ag(111) surface, and the second demonstrates interaction strength of (Ag(55))(2) dimers with and without chloridation. Based on our calculated energy barriers, Ag(n)Cl(m) clusters are more mobile than Ag(n) clusters for n = 1-4. The binding energy between two Ag(55) clusters is significantly reduced by surface chloridation. Bond weakening and enhanced mobility are two important mechanisms underlying corrosion and fragmentation processes.

Dynamics of polymorphic nanostructures: from growth to collapse.

Metal cluster provides an ideal object to study a many body system. In particular it consists of many electrons which strongly interact each other. Two kinds of electrons may be distinguished i.e.: the valence electrons which become more delocalized as the cluster size increases, and the core electrons which may remain localized around each nucleus whatever the cluster size is. The correlations between the electrons, within each variety, induce collective effects revealed by the observation of giant resonances.