A. Domps

Large amplitude dynamics of clusters and nuclet

We discuss and compare the dipole resonance modes in nuclei and metal clusters under varying conditions: different excitation mechanisms in the case of nuclei, changed back-ground structure in the case of clusters. The resonances are generally nicely harmonic modes, even those with a large amplitude. Only extreme shapes, as they occur in fusion and fission, can perturb this harmonicity.

ON MICROSCOPIC INSIGHTS INTO METAL CLUSTER FRAGMENTATION

Metal cluster fragmentation has been a topic of intense experimental activity for many years [1,2,3]. In many early investigations the excitation process, for example through a low fluence nanosecond laser, leads to an excited cluster in which both electronic and ionic degrees of freedom were simultaneously excited. The such produced highly charged cluster was thus already at thermal equilibrium and its further deexcitation proceeded by evaporation, fission or fragmentation, and could be accessed to by statistical concepts [4]. With the advent of more instantaneous excitation processes, namely at a time scale typical of electronic characteristic times, the situation is somewhat different as excitation and initial ionization proceed at once, thus placing the charged cluster in a definitively far from equilibrium state. The understanding of the further evolution of the system thus requires a proper description of the electronic degrees of freedom and of their coupling to ionic o nes.

Nonlinear electronic dynamics in free and deposited sodium clusters : Quantal and semi-classical approaches

The optical response of sodium clusters is studied using fully three-dimensional electronic dynamics, in real time, with an explicit ionic background. The obtained spectra are shown to come close to experimental results for free clusters. We use the approach also to compute the response of sodium clusters deposited on a NaCl(1 0 0) surface. The flattening of the clusters induced by the surface results in a shift and a large fragmentation of the plasmon resonance.