Toward the optimization of double-pulse LIBS underwater: effects of experimental parameters on the reproducibility and dynamics of laser-induced cavitation bubble.

Double-pulse laser-induced breakdown spectroscopy (LIBS) was recently proposed for the analysis of underwater samples, since it overcomes the drawbacks of rapid plasma quenching and of large continuum emission, typical of single-pulse ablation. Despite the attractiveness of the method, this approach suffers nevertheless from a poor spectroscopic reproducibility, which is partially due to the scarce reproducibility of the cavitation bubble induced by the first laser pulse, since pressure and dimensions of the bubble strongly affect plasma emission. In this work, we investigated the reproducibility and the dynamics of the cavitation bubble induced on a solid target in water, and how they depend on pulse duration, energy, and wavelength, as well as on target composition.

Dendrimer-capped nanoparticles prepared by picosecond laser ablation in liquid environment.

Fifth generation ethylendiamine-core poly(amidoamine) (PAMAM G5) is presented as an efficient capping agent for the preparation of metal and semiconductor nanoparticles by ps laser ablation in water. In particular, we describe results obtained with the fundamental, second and third harmonic of a ps Nd:YAG laser and the influence of laser wavelength and pulse energy on gold particle production and subsequent photofragmentation. In this framework, the role of the dendrimer and, in particular, its interactions with gold clusters and cations are accounted.

Harmonic interferometry in the visible and UV, based on second- and third-harmonic generation of a 25 ps mode-locked Nd:YAG laser.

A second-harmonic interferometer using 25 ps pluses is presented, achieving a sensitivity of 9x10(-10) m in measuring line-integrated dispersion between 1064 and 532 nm. Using the same laser source, a third-harmonic interferometer is demonstrated for the first time to our knowledge, achieving a sensitivity of 7x10(-9) m in measuring line-integrated dispersion between 1064 and 355 nm. The prospect for the development and use of high-harmonic interferometry is discussed.

Versatile second-harmonic interferometer with high temporal resolution and high sensitivity based on a continuous-wave Nd:YAG laser.

A second-harmonic interferometer based on a CW Nd:YAG laser is presented. The versatile device measures the line-integrated dispersion at the fundamental and second-harmonic wavelengths. A temporal resolution of 1.