Artículos de revista DCIE - ZIES Aldizkari artikuluak

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Browsing Artículos de revista DCIE - ZIES Aldizkari artikuluak by Author "Aguilera Andoaga, José Antonio"

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    PublicationOpen Access
    Direct analysis of aluminum alloys by CSigma laser-induced breakdown spectroscopy
    (Elsevier, 2018) Aragón Garbizu, Carlos; Aguilera Andoaga, José Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
    We report the application of CSigma laser-induced breakdown spectroscopy (Cσ-LIBS) to quantitative analysis of aluminum alloys without sample preparation. Cσ-LIBS simplifies strongly the conventional calibration procedure of LIBS, replacing it with a characterization stage performed from the spectrum of a single standard sample. The aim of this work has been to provide a complete evaluation of the use of Cσ-LIBS for direct analysis by obtaining its figures of merit, including precision and limits of detection. Ten elements (Si, Fe, Cu, Mn, Mg, Cr, Ni, Zn, Ti and Ca) are determined in a set of six certified samples with a wide range of concentrations, from percent down to μg/g levels. The average precision is 8.0% for concentrations higher than 0.1 wt% and 13% for concentrations between 0.1 wt% and 0.01 wt%. The limits of detection are in the range 1.4–9.7 μg/g.
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    PublicationOpen Access
    Experimental Stark widths and shifts of MnII spectral lines
    (Oxford University Press, 2019) Manrique Rosel, Javier; Aragón Garbizu, Carlos; Aguilera Andoaga, José Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
    Stark widths and shifts of MnII lines with wavelengths in the range 2300-3500 Å have been measured by laser-induced breakdown spectroscopy. The use of fused glass samples with varying Mn concentrations has allowed minimization of the error due to self-absorption in the Stark width measurements, which has made it possible to include resonance lines in the study. The laser-induced plasmas are characterized along their temporal evolution, showing electron densities in the range (0.60-6.75)×1017 cm-3 and temperatures in the range 11 000-13 900 K. The results are compared with experimental and theoretical values available in the literature.
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    PublicationOpen Access
    Experimental stark widths and shifts of V II spectral lines
    (Oxford University Press, 2020) Manrique Rosel, Javier; Díaz Pace, D. M.; Aragón Garbizu, Carlos; Aguilera Andoaga, José Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
    We have measured the Stark widths and shifts of V II spectral lines in the wavelength range 2000-4200 Å belonging to 75 multiplets. The spectra are emitted by laser-induced plasmas generated from fused glass discs prepared by borate fusion. The electron density and temperature are in the ranges (0.72-6.5) × 1017 cm-3 and (11 000-14 900) K, respectively. To avoid self-absorption, we have used seven samples with vanadium concentrations selected by the CSigma graph methodology. This has allowed to include strong and weak lines in the study, including resonance and forbidden lines. The experimental widths and shifts are compared with theoretical values available in the literature.
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    PublicationOpen Access
    New procedure for CSigma laser induced breakdown spectroscopy addressing the laser-induced plasma inhomogeneity
    (Elsevier, 2024-06-06) Aguilera Andoaga, José Antonio; Aragón Garbizu, Carlos; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
    CSigma laser-induced breakdown spectroscopy (Cσ-LIBS), as the other methods for quantitative elemental analysis by LIBS based on plasma characterization, is negatively affected by the inhomogeneity of laser-induced plasmas. In the present work, we propose a new procedure for Cσ-LIBS which addresses the plasma inhomogeneity problem. The key features of the method are: (1) the extension of the concept of apparent temperature to other plasma parameters (apparent plasma) and its use in both the ionization and excitation equilibria and (2) the addition to the theoretical Cσ curve of a linear contribution arising from the plasma regions of low optical depth. In ionization equilibrium, the inhomogeneity requires separated Cσ graphs and different apparent ionization temperatures for neutral atom and ion emissions. In excitation equilibrium, we account for the inhomogeneity by obtaining a different apparent temperature for each multiplet included in the Cσ graph. In this way, the procedure only requires the fitting of a limited number of parameters to describe the inhomogeneous plasma, as the multiplet temperatures Ti are determined by a straightforward iteration procedure of fast convergence. The improved treatment of plasma inhomogeneity allows to include intense resonance lines in Cσ graphs, which were previously avoided. The development of the method has demanded accurate experimental Cσ graphs, obtained with seven certified aluminum alloys. The laser-induced plasma is generated in air at atmospheric pressure, the most common and versatile ambient gas condition for LIBS, which is known to produce a strongly inhomogeneous plasma. To validate the analytical application of the method, the samples are divided into three characterization samples and four analytical samples. The average deviation of the determined concentrations from the certified values has been 8.5% for elements with concentrations greater than 0.05 wt%.