A simple and cost-effective variant of laser induced breakdown spectroscopy is presented that involves a double simultaneous pulse configuration employing a single laser source. Its performance is compared with conventional single pulse configuration. Double simultaneous pulses were accomplished by splitting a Nd:YAG laser (1064 nm, 6 ns, 360 mJ) beam into two components that were focused on the sample surface to produce two concurrent breakdowns. Experiment was repeated for single pulse and double simultaneous pulses under different ambient pressures. The performance was evaluated on the basis of self-absorption, signal-to-noise ratio (SNR), and relative standard deviation (RSD) of the Mg II doublet (280.2704 nm, 279.553 nm). Optically thin emission lines of better profiles with higher signal-to-noise ratio resulted from double simultaneous pulses. The lowest relative standard deviations obtained by single pulse and double simultaneous pulse configurations were 18.89% and 12.01%, respectively. In fact, double simultaneous pulses have performed better than single pulse in all respects within the studied regime.
Laser Induced Breakdown spectroscopy (LIBS) is an extremely potential spectroscopic analytical tool. A highly focused laser bean stiochiometerically ablates the surface of the material in the form of a plasma plume. Excited species in the plasma plume emit their characteristic wavelengths upon de-excitation which are collected, dispersed and analyzed for qualitative and quantitative analyses. Basic LIBS setup includes a laser, target sample, optical fiber and a spectrometer. However it has been used in different configurations like single–pulse and double pulse configurations. LIBS has several advantages over other currently practiced analytical techniques in terms of higher resolution, better limit of detection (LOD), negligible sample preparation etc. Despite of all these advantages it is suffering from poor accuracy and reproducibility of results due to uncontrolled atmosphere around the targeted sample and variations in other experimental parameters. In order to improve reliability of LIBS in terms of accuracy and reproducibility we have designed a methodology for experimentation under controlled environmental conditions inside an especially designed ablation chamber. We will make use of multiple simultaneous laser pulses, which are supposed to play a significant role in improving the analytical accuracy of LIBS particularly for non homogeneous samples. In this article we will briefly review the basics of LIBS, its types, common instrumentations, advantages, limitations applications and at the end our proposed methodology.
Laser Induced Breakdown Spectroscopy is a strong analytical method for qualitative studies and Support Vector Machines (SVM) is a powerful machine learning technique for pattern recognition and classification. In this paper we present an application of LIBS qualitative capability reinforced by SVM classification. Three different samples were ablated by an Nd:YAG laser and their spectra were recorded by Ocean Optics HR4000 spectrometer. These spectra possess signatures of the ablated materials. Sometimes these are visible to the naked eye while in many cases it is hard to decide about the presence of any pattern identifying a particular material. In addition variations are always found in the spectra obtained from laser induced ablation. In this situation a pattern recognition tool is very useful that sweep through the whole spectrum and record minor details. Here SVM serves the purpose. SVM classifiers were trained with distinct sets of spectra, belonging to specific materials, for classification. The results obtained from this preliminary experiment are encouraging and can lead us on positive grounds for the future work. This combination of tools can prove to be valuable for fast and automated identification and classification.
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