Robert Botet

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Nonlinear optical phenomena on rough self-affine metal surfaces are theoretically studied. Placing nonlin-early polarizable molecules on such surfaces results in strong enhancement of optical nonlinearities. A quasi-static approximation is used to calculate local-enhancement factors for the second and third harmonic generation , degenerate four-wave mixing,(More)
Surface-enhanced Raman scattering (SERS) from a self-affine surface is shown to be very large. A theory is developed expressing this SERS in terms of the eigenmodes of a self-affine surface; the theory successfully explains the observed SERS from cold-deposited thin films that are known to have a self-affine structure. Spatial distributions of local fields(More)
Fractal nanostructured materials, such as nanocomposites and self-affine thin films, are shown to possess giant optical nonlinearities. The enhancement results from the sub-wavelength local-ization of dipolar modes and strong local field fluctuations. Optical phenomena experience giant enhancements in metal nanocomposites and rough thin films consisting of(More)
Distributions of the largest fragment charge, Zmax, in multifragmentation reactions around the Fermi energy can be decomposed into a sum of a Gaussian and a Gumbel distribution, whereas at much higher or lower energies one or the other distribution is asymptotically dominant. We demonstrate the same generic behavior for the largest cluster size in critical(More)
In this contribution we show that the biggest fragment charge distribution in central collisions of 129 Xe+ nat Sn leading to multifragmentation is an admixture of two asymptotic distributions observed for the lowest and highest bombarding energies. The evolution of the relative weights of the two components with bombarding energy is shown to be analogous(More)
We have performed molecular dynamics simulations of an intruder in a vibrated granular bed including interstitial fluid effects to account for the phenomenon of reverse buoyancy. We show that our model is able to reproduce the overall behaviour observed by previous experimental works and is the first finite-elements simulation to show the sinking of(More)
We have developed a novel computational scheme that allows direct numerical simulation of the mechanical behavior of sticky granular matter under stress. We present here the general method, with particular emphasis on the particle features at the nanometric scale. It is demonstrated that, although sticky granular material is quite complex and is a good(More)
Preface Professor Ping Sheng, who became one of the protagonists in the physics of random inhomogeneous media, told me once that, when he started research in this field thirty years ago, his senior colleagues tried to discourage him from studying " dirty " materials and suggested he focused on traditional " nice " solids, such as crystals. Nowadays, it has(More)
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