This paper presents a novel model aimed at describing the basic phenomena that cause the fragmentation of a single Au nanoparticle (AuNP) by interaction with the second and the third harmonics of a Nd:YAG picosecond laser. In order to verify the model through a comparison with experimental results, we extended the single-AuNP fragmentation model to treat the macroscopic bleaching of a suspension of AuNPS. The sample of AuNPs is obtained by laser ablation in all aqueous solution Of fifth generation ethylendiamine-core poly(amidoamine) (PAMAM-G5) with the fundamental wavelength of the same laser at 1064 nm. The dependence of photobleaching oil the laser pulse energy at 355 and 532 nm is studied and hence compared with the theoretical model. In particular, we discuss the role of heating and the interplay among pure thermal processes, e.g., melting and evaporation, thermoionic emission, and photon-assisted ionization. We show that, although the AuNP temperature call overcome the evaporation threshold ill our range of investigation, the experimental curves disagree with a process of fragmentation mainly driven by heating. Our results highlight the role of photon-assisted transitions in AuNP fragmentation and allow us to discuss different regimes of fragmentation at different fluences and intensities. Moreover, we show that PAMAM-G5 plays a crucial role in Our experiments

A hot stable field-reversed configuration (FRC) has been produced in the C-2 experiment by colliding and merging two high-β plasmoids preformed by the dynamic version of field-reversed θ-pinch technology. The merging process exhibits the highest poloidal flux amplification obtained in a magnetic confinement system (over tenfold increase). Most of the kinetic energy is converted into thermal energy with total temperature (T{i}+T{e}) exceeding 0.5 keV. The final FRC state exhibits a record FRC lifetime with flux confinement approaching classical values. These findings should have significant implications for fusion research and the physics of magnetic reconnection.

Fifth-generation ethylendiamine-core poly(amidoamine) (PAMAM G5)-capped gold nanoparticles were prepared by picosecond laser ablation in water, with the fundamental and second harmonic of a picosecond Nd:YAG laser. Although the visible wavelength exhibited a lower ablation threshold than that of the infrared one, the ablation process at 532 nm reached early saturation because of both linear and nonlinear absorption mechanisms, accompanied by fragmentation of existing nanoparticles. We demonstrate that the onset of the fragmentation can be monitored by simple UV−vis spectroscopy, thanks to the ability of PAMAM G5 to stabilize gold cations, which results in the growth of an intense band at 290 nm. We observed that, while with 532 nm (2.33 eV) irradiation a two-photon absorption mechanism induces fragmentation of the nanoparticles, the suspensions remain stable when irradiated with 1064 nm (1.17 eV) up to 60 GW/cm2.