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Arroyo Seco, Argentina

Pardini L.,CNR Institute of Neuroscience | Legnaioli S.,CNR Institute of Neuroscience | Lorenzetti G.,CNR Institute of Neuroscience | Palleschi V.,CNR Institute of Neuroscience | And 6 more authors.
Spectrochimica Acta - Part B Atomic Spectroscopy | Year: 2013

In this work, different theories for the determination of the electron density in Laser-Induced Breakdown Spectroscopy (LIBS) utilizing the emission lines belonging to the hydrogen Balmer series have been investigated. The plasmas were generated by a Nd:Yag laser (1064 nm) pulsed irradiation of pure hydrogen gas at a pressure of 2 · 104 Pa. Haα, Hβ, Hγ, Hδ, and Balmer lines were recorded at different delay times after the laser pulse. The plasma electron densitywas evaluated through themeasurement of the Stark broadenings and the experimental results were compared with the predictions of three theories (the Standard Theory as developed by Kepple and Griem, the Advanced Generalized Theory by Oks et al., and the method discussed by Gigosos et al.) that are commonly employed for plasma diagnostics and that describe LIBS plasmas at different levels of approximations. A simple formula for pure hydrogen plasma in thermal equilibriumwas also proposed to infer plasma electron density using the Hα line. The results obtained showed that at high hydrogen concentration, the Hα line is affected by considerable self-absorption. In this case, it is preferable to use the Hβ line for a reliable calculation of the electron density. © 2013 Elsevier B.V. All rights reserved. Source

Torre M.S.,Institute Fisica Arroyo Seco | Quirce A.,University of Cantabria | Valle A.,University of Cantabria | Pesquera L.,University of Cantabria
Journal of the Optical Society of America B: Optical Physics | Year: 2010

We report on a theoretical and experimental investigation of the bistable behavior of the polarization of longwavelength single-transverse mode vertical-cavity surface-emitting lasers (VCSELs) when subject to orthogonal optical injection. We have studied the bistability properties of the polarization switching that appear when changing the master laser wavelength with a fixed master laser power. Two bistable regions are found for polarization switchings appearing at short and long wavelengths. The directions of the obtained hysteresis cycles are in agreement with the experimental results. The widths of both bistable regions are also found to be similar and nearly independent of the injected power. The width of the region where polarization switching takes place is shown to increase as the injected power is increased. A good overall qualitative agreement is found between our theoretical and experimental results. © 2010 Optical Society of America. Source

Albaladejo S.,Autonomous University of Madrid | Lester M.,Institute Fisica Arroyo Seco | Lester M.,CONICET | Saenz J.J.,Autonomous University of Madrid
Journal of the Optical Society of America B: Optical Physics | Year: 2011

Light transmission through a finite photonic crystal waveguide with an embedded cavity is analyzed in terms of the optical conductance (OC). Under appropriate conditions, the transmission is inhibited for any angle of incidence. The resonance condition manifests itself as a "dip" in the OC. Just at the resonance, the power flow presents strong vortices inside the cavity. © 2011 Optical Society of America. Source

Legnaioli S.,CNR Institute of Neuroscience | Lorenzetti G.,CNR Institute of Neuroscience | Pardini L.,CNR Institute of Neuroscience | Palleschi V.,CNR Institute of Neuroscience | And 8 more authors.
Spectrochimica Acta - Part B Atomic Spectroscopy | Year: 2012

In this paper, we discuss the application of laser-induced breakdown spectroscopy to precious metal alloys used for the control of the process of recovery and recycling of scraps and waste of industrial processes. In particular, the possibility to obtain sensitivity and trueness comparable to the current systems used in industrial environment in the quantitative determination of the elements of interest was explored. The present study demonstrates that laser-induced breakdown spectroscopy can be considered as a viable alternative to inductively coupled plasma optical emission spectrometry and X-ray fluorescence spectroscopy for the determination of recovered precious metals. The limits of detection obtained are of the order of 0.2 mg/g for all the elements considered. The maximum deviation with respect to the nominal concentrations is around 1 mg/g at concentrations around 20 mg/g (gold) corresponding to a relative error slightly higher than ± 5%. © 2012 Elsevier B.V. Source

Diaz Pace D.M.,Institute Fisica Arroyo Seco | Diaz Pace D.M.,CONICET | Gabriele N.A.,Campus Universitario | Garcimuno M.,Institute Fisica Arroyo Seco | And 5 more authors.
Spectroscopy Letters | Year: 2011

Laser-induced breakdown spectroscopy (LIBS) technique was applied for rapid analysis of major and minor elements composing geological samples including minerals, rocks, and a soil sample. The plasma was produced in air at atmospheric pressure by focusing on the targets a pulsed infrared Nd:YAG laser in open-path configuration. The emitted light in the UV-Vis was analyzed by a compact LIBS system to measure spectral emission lines of Si, Al, Fe, Ca, Na, K, Mg, C, Cu, Mn, and Ti. The experimental issues relevant for the analysis of the different samples were investigated by taking into account their peculiar features: drilling through a weathered layer, roughness and grain-size considerations, statistical averaging, and accuracy of the measurements. In this approach, the characterization of the samples was achieved by studying the relative variations of the emission intensities of each element normalized with respect to an internal standard. The present study shows the usefulness of LIBS as a tool for reliable identification of field samples. Copyright © Taylor & Francis Group, LLC. Source

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