Hydrogen Balmer alpha line behavior in Laser-Induced Breakdown Spectroscopy depth scans of Au, Cu, Mn, Pb targets in air

Year: 2010

Authors: Senesi G.S., Benedetti P.A., Cristoforetti G., Legnaioli S., Palleschi V.

Autors Affiliation: Institute of Inorganic Methodologies and Plasmas, Via Amendola 122/D, 70126 Bari, Italy; Applied Laser Spectroscopy Laboratory, Institute of Chemical-Physical Processes, Research Area of National Research Council, Via G. Moruzzi 1, 56124 Pisa, Italy

Abstract: The behavior of hydrogen spectral emission of the plasmas obtained by Laser-Induced Breakdown Spectroscopy (LIBS) measurement of four metal targets (Au, Cu, Mn, Pb) in air was investigated. The plasma was produced by a pulsed Nd:YAG laser emitting in the fundamental wavelength. A systematic study of the spatial-integrated plasma emission obtained by an in-depth scanning of the target was performed for each metal, both in single pulse and collinear double-pulse configurations. Further, a spatial-resolved analysis of the emission of plasma produced on the Al target by a single laser pulse was performed, in order to describe the spatial distribution of emitters deriving from the target and air elements. The line intensities of the main plasma components (target metal, nitrogen, oxygen and hydrogen) were measured in both experimental conditions. Results show that the hydrogen line intensity varies greatly as a function of the metal considered, and exhibits a marked decrease after the first laser shots. However, differently from emission lines due to surface impurities, the hydrogen line intensity reaches a constant level deep inside the target. The spatial-resolved measurements indicate that hydrogen atoms in the plasma mainly derive from the target surface and, only at a minor extent, from the dissociation of molecular hydrogen present in the surrounding air. These findings show that the calculation of plasma electron number density through the measurement of the Stark broadening of hydrogen Balmer alpha line is possible also in depth scanning measurements. (C) 2010 Elsevier B.V. All rights reserved.


Volume: 65 (7)      Pages from: 557  to: 564

More Information: One of the authors (G.S.S.) acknowledges the support of the CNR program for mobility of researchers.
KeyWords: LIBS; Hydrogen Balmer alpha line; Plasma; Metals;
DOI: 10.1016/j.sab.2010.05.010

Citations: 9
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