Colloidal nanoparticles: Mechanisms of laser synthesis and interactions
Laser ablation in liquids is now commonly used to produce colloidal nanoparticles (NPs) that have found numerous applications in different areas. In the experiments, NPs of different materials can be rather easily produced by using laser systems with various pulse durations, shape, wavelengths, and fluence. Here, we focus our attention on metal nanoparticles produced by ultra-short laser pulses.
Laser ablative nanostructuring of Au in liquid ambience in continuous wave illumination regime
Gold nanoparticles (Au NPs) attract particular attention because of their unique size-dependent chemical, physicochemical and optical properties and, hence, their potential applications in catalysis, nanoelectronics, photovoltaics and medicine. In particular, laser-produced colloidal nanoparticles are not only biocompatible, but also reveal unique chemical properties. Different laser systems can be used for synthesis of these colloids, varying from continuous wave (CW) to ultra-short femtosecond lasers. The choice of an optimum laser system is still a challenge in application development. To bring more light at this issue, we investigate an influence of laser parameters on nanoparticle formation from a gold target immersed in deionized water. First, an optical diagnostics of laser-induced hydrodynamic processes taking place near the gold surface is performed. Then, gold nanoparticle colloids with average particle sizes smaller than 10 nm and a very narrow dispersion are shown to be formed by CW laser ablation. The obtained results are compared with the ones obtained by using the second harmonics and with previous results obtained by using femtosecond laser systems.
La inseguridad jurídica en normas de contratación estatal
It is established by different studies that the issue of government procurement has been marred by several factors, the test objective to publicize these factors, we take as starting point the constant conflict between the branches of government to try and organize this subject; will collect and analyze diverse regulatory and case material in order to achieve evidence and demonstrate the different concepts of constant change that produces excessive regulation of the subject procurement and is in turn causing rapid changes that result in legal uncertainty for our law on the Contract Status.