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Laser-induced breakdown spectroscopy with improved detection sensitivity, selectivity, and reliability
As a powerful real-time and in-situ elemental analysis technique, laser-induced breakdown spectroscopy (LIBS) has attracted more and more interests. To develop an ultrasensitive and highly accurate trace element detection system based on LIBS, it is necessary to improve the LIBS detection sensitivity, selectivity, and reliability. ^ Firstly, the detection sensitivity of LIBS is element dependent and the limits of detection (LODs) for some elements are very poor. Due to the quick expansion and fast motion of the laser-induced plasmas, the lifetime of laser-induced plasmas is very short (typically microseconds). Secondly, the interference effects limit the LIBS detection selectivity and reliability. The LIBS spectra for most elements are very complex and sometimes false identifications may be made because emission lines from many elements overlap with each other in wavelength. Finally, the matrix effects also limit the LIBS detection sensitivity and reliability since the emission intensity from the target element depends on not only the concentration, but also the chemical and physical properties of the matrix. ^ In this dissertation, a novel technique to improve the LIBS detection sensitivity based on spatially-confined LIBS will be introduced, which is simple and economic. This approach can improve the detection sensitivity by a factor of 10. LIBS combined with laser-induced fluorescence (LIBS-LIF) has been studied to demonstrate the capability of LIBS in trace element detection. The detection sensitivity can be improved by a factor of 50. During the cooling process of the laser-induced plasmas, the transient radicals will be formed and the Raman spectra of the radicals have been studied. By combining Raman spectroscopy of overcooled laser-induced plasmas with LIBS, the detection reliability will be further improved. The potential to detect isotopes using Raman spectroscopy of overcooled laser-induced plasmas will also be discussed. ^ In summary, the spatial confinement of plasmas in LIBS can improve the LIBS detection sensitivity; LIBS-LIF can improve both the LIBS detection sensitivity and selectivity; and Raman spectroscopy of overcooled laser-induced plasmas can improve the LIBS reliability. By integrating all these benefits into one single system, an ultrasensitive, selective and highly accurate trace element detection approach has been developed.^
Engineering, Electronics and Electrical
Shen, Xiaokang, "Laser-induced breakdown spectroscopy with improved detection sensitivity, selectivity, and reliability" (2009). ETD collection for University of Nebraska - Lincoln. AAI3360164.