Comparison of Heat Affected Zone due to nanosecond and femtosecond laser pulses using Transmission Electronic Microscopy

International audienceThis letter presents a method aimed at quantifying the dimensions of the heat-affected zone ~HAZ!, produced during nanosecond and femtosecond laser–matter interactions. According to this method, 0.1 mm thick Al samples were microdrilled and observed by a transmission electronic microscopy technique. The holes were produced at laser fluences above the ablation threshold in both nanosecond and femtosecond regimes ~i.e., 5 and 2 J/cm2, respectively!. The grain size in the samples was observed near the microholes. The main conclusion is that a 40 mm wide HAZ is induced by the nanosecond pulses, whereas the femtosecond regime does not produce any observable HAZ. It turns out that the width of the femtosecond HAZ is less than 2 mm, which is our observation limit

Universal scaling of plasmon coupling in metal nanostructures: Checking the validity for higher plasmonic modes using second harmonic generation

The universal scaling of plasmon coupling in metallic nanostructures is now a well-established feature. However, if the interaction between dipolar plasmon modes has been intensively studied, this is not the case of the coupling between higher order ones. Using Mie theory extended to second harmonic generation, we investigate the coupling between quadrupolar plasmon modes in metallic nanoshells. Like in the case of dipolar plasmon modes, a universal scaling behavior is observed in agreement with the plasmon hybridization model

Second harmonic scattering from silver nanocubes

The second harmonic light scattered from silver nanocubes dispersed in an aqueous suspension is investigated. The first hyperpolarizability is determined and corrected for resonance enhancement. It is shown to be similar to that of silver nanospheres with a comparable volume. The polarization-resolved analysis of the scattered harmonic intensity exhibits a surface response strongly modulated by the different multipolar field contributions. As a result, the shape does not play a leading role anymore for nanoparticles with a centrosymmetric shape when retardation must be considered. Comparing the right angle and forward-scattered polarized intensity responses, the unequal balance of the eight nanocube corners' contribution to the total response is revealed despite the high degree of centrosymmetry of the cubic shape. It is then demonstrated with a simple model that the nanocubes' first hyperpolarizability exhibits an octupolar tensorial symmetry. The surface integral equation method calculations are finally provided to investigate further the role of the corners’ and edges’ rounding

Etude des adverbes d'énonciation et des adverbes d'énoncé en français et en thaï (éléments de comparaison)

TOULOUSE2-BUC Mirail (315552102) / SudocSudocFranceF

Génération d un continuum de lumière blanche pour l analyse spectrale résolue en temps de milieux très diffusants.

International audienceUne nouvelle technique kilohertz de mesure de temps de vol picoseconde sur un large domaine spectral est détaillée. Le dispositif se compose d un laser femtoseconde avec amplification à dérive de fréquence et d une caméra à balayage de fente monocoup couplé a un polychromateur. Un continuum de lumière blanche est généré dans de l eau de manière à obtenir une source 450-750 nm la plus intense. Les images obtenues permettent une analyse spectrale et temporelle simultanée dont la résolution en temps de vol est inférieure à 5 mm pour un temps d intégration inférieur à 60 seconde

Wakeful rest promotes the viewpoint invariance, but not the fine discriminability, of entities mnemonic representations for subsequently familiarity-based recognition

International audienc

Génération d un continuum de lumière blanche pour l analyse spectrale résolue en temps de milieux très diffusants.

International audienceUne nouvelle technique kilohertz de mesure de temps de vol picoseconde sur un large domaine spectral est détaillée. Le dispositif se compose d un laser femtoseconde avec amplification à dérive de fréquence et d une caméra à balayage de fente monocoup couplé a un polychromateur. Un continuum de lumière blanche est généré dans de l eau de manière à obtenir une source 450-750 nm la plus intense. Les images obtenues permettent une analyse spectrale et temporelle simultanée dont la résolution en temps de vol est inférieure à 5 mm pour un temps d intégration inférieur à 60 seconde