%0 Journal Article
%T Stoichiometric Analysis of Inorganic Compounds Using Laser-Induced Breakdown Spectroscopy with Gated and Nongated Spectrometers
%A Sreedhar Sunku
%A Ashwin Kumar Myakalwar
%A Manoj Kumar Gundawar
%A Prem Kiran Paturi
%A Surya Praksh Tewari
%A Venugopal Rao Soma
%J ISRN Optics
%D 2012
%R 10.5402/2012/631504
%X We describe our results obtained from stoichiometric ratio studies of three different energetic, inorganic samples (ammonium perchlorate (AP), boron potassium nitrate (BPN), and ammonium nitrate (AN)) using the technique of laser-induced breakdown spectroscopy (LIBS) with nanosecond pulses. Signal collection was independently executed using both gated and nongated spectrometers. The oxygen peak at 777.31£¿nm (O) and nitrogen peaks at 742.50£¿nm (N1), 744.34£¿nm (N2), and 746.91£¿nm (N3) were used for evaluating the O/N ratios. Temporal analysis of plasma parameters and ratios was carried out for the gated data. O/N1, O/N2, and O/N3 ratios retrieved from the gated AP data were in excellent agreement with the actual stoichiometry. In the case of gated BPN data, O/N2 and O/N3 ratios were in good agreement. The stoichiometry results obtained with nongated spectrometer, although less accurate than that obtained with gated spectrometer, suggest that it can be used in applications where fair accuracy is sufficient. Our results strongly indicate that non-gated LIBS technique is worthwhile in the kind of applications where precision classification is not required. 1. Introduction Nanosecond (ns) laser-induced breakdown spectroscopy (LIBS) has been extensively employed in elemental analysis, impurity detection [1, 2], and identification/classification of materials [3, 4]. In recent years this technique has been applied to study a variety of materials such as alloys, biological samples, pharmaceuticals, and explosives amongst various others [5¨C8]. The strength of this technique emanates from prerequisites that an ideal analytical tool should possess¡ªminimal sample preparation, simultaneous multielement detection, ability to analyze all three states of matter, the necessity of short-time scales involved for measurement and analysis, and most importantly the capability of remote detection. In most of the cases requirement for sample preparation is negligible. This technique involves the interaction of an intense laser pulse with a sample leading to plasma generation [9¨C12]. The material absorbs light through multiphoton/inverse Bremsstrahlung process that heats the sample surface further to which electrons acquire energy, and as the energy absorbed grows, it leads to collisions and breakdown. Breakdown is followed by the plasma expansion and consequently the creation of shock waves. The plasma expansion rate is observed to be highest towards the focusing lens [13]. During the cooling stage constituent ions/electrons of expanding plasma recombine to form neutral atoms,
%U http://www.hindawi.com/journals/isrn.optics/2012/631504/