Nanoparticles find applications in multiple technological and scientific fields, and laser ablation in liquid (LAL) emerged as a versatile method for providing colloidal solutions of nanomaterials with various composition, by a low cost, simple, self-standing, and "green" procedure. However, the use of high energy and high power laser beams is harmful, especially when coupled with flammable or toxic liquids, and in situ operation is required for starting, monitoring the LAL synthesis, and stopping it at the desired point. Here we describe the hardware and software design and the test results of a system for the production of nanoparticles by laser ablation synthesis in liquid solution (LASiS), which is remotely controllable with a personal computer or a smartphone. In this system, laser energy and solution flux are selectable, and the synthesis status can be monitored and managed at any time off site. Only commercially available components and software are employed, making the whole apparatus easily reproducible in any LAL laboratory. The system has proven its reliability in various conditions, including intercontinental remote control experiments. Overall, this apparatus represents a step forward to improve the safety and to more efficiently exploit the time of people working with LASiS, thus contributing to the increasing demand for off-site real time monitoring of experimental equipment in many scientific and industrial laboratories, due to safety and efficiency requirements.

Dependence of the localized surface plasmon resonance of noble metal quasispherical nanoparticles on their crystallinity-related morphologies This paper develops a novel method for simultaneously determining the plasma frequency x P and the damping constant c f ree in the bulk damped oscillator Drude model, based on experimentally measured real and imaginary parts of the metal refractive index in the IR wavelength range, lifting the usual approximation that restricts frequency values to the UV-deep UV region. Our method was applied to gold, silver, and copper, improving the relative uncertainties in the final values for x p (0.5%-1.6%) and for c f ree (3%-8%), which are smaller than those reported in the literature. These small uncertainties in x p and c f ree determination yield a much better fit of the experimental complex dielectric function. For the case of nanoparticles (Nps), a series expansion of the Drude expression (which includes x p and c f ree determined using our method) enables size-dependent dielectric function to be written as the sum of three terms: the experimental bulk dielectric function plus two size corrective terms, one for free electron, and the other for bound-electron contributions. Finally, size distribution of nanometric and subnanometric gold Nps in colloidal suspension was determined through fitting its experimental optical extinction spectrum using Mie theory based on the previously determined dielectric function. Results are compared with size histogram obtained from Transmission Electron Microscopy (TEM). V C 2014 AIP Publishing LLC.

Synthesis of nickel (Ni) nanoparticles (NPs) suspensions was performed using a 120 femtosecond (fs) pulse laser to ablate a Ni solid target in n-heptane and water.Analysis of structure, configuration and sizing was carried out using different independent techniques such as Optical Extinction Spectroscopy (OES), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM) and Electron Diffraction (ED), which yield interrelated information.AFM microscopy allows determining the spherical shape and size distribution of the NPs in the obtained colloids while TEM provides knowledge about shape, structure and size distribution. ED allows identification of the different metal and metal oxide composition as well as their crystallographic phase. On the other hand, OES gives information related to size distribution, structure, configuration and composition.Interpretation of these spectra is based on Mie theory which, in turn, depends on Ni dielectric function. For NPs radii smaller than 3 nm, size-dependent free and bound electron contributions to the dielectric function must be considered. To account for the full size span, complete Mie expansion was used for optical extinction cross-section calculations. A theoretical analysis of the dependence of plasmon resonance of bare core and core-shell Ni NPs with core size and shell thickness provide insight about their spectroscopic features.For n-heptane, species like bare core Ni and hollow Ni NPs are found in the colloid, being the latter reported for the first time in this work. Instead, for water, the colloid contains hollow nickel NPs and nickel oxide in different core-shell configurations: Ni-NiO and NiO-Ni, being the latter also reported for the first time in this paper. In both cases, size distribution agrees with that derived from TEM and AFM analysis. The formation of the oxide species is discussed in terms of oxidation-reduction processes during ablation. Possible mechanisms for the formation of hollow species are proposed.