Multi-element Saha Boltzmann plot (MESBP) coupled calibration-free laser-induced breakdown spectroscopy (CF-LIBS): an efficient approach for quantitative elemental analysis

Abstract

The development of calibration-free laser-induced breakdown spectroscopy (CF-LIBS) has reduced the challenges faced by quantitative elemental analysis using conventional methods and expanded the scope of LIBS as an analytical technique. In conventional CF-LIBS, the y-intercept of the Boltzmann plot is used for estimating the concentration of individual species in the sample and hence the sensitivity of species concentration to the slope is very high. Since the Boltzmann plot considers lines of single species, the conventional LIBS is prone to uncertainties in transition probability, statistical fluctuations, and self-absorption. These issues, to an extent, can be dealt with by considering a generalised approach for temperature evaluation, such as the multi-element Saha Boltzmann Plot (MESBP) method. In this work, we combined MESBP with time-gated CF-LIBS through a regressive algorithm to enhance the accuracy of quantitative analysis. A comparative study between CF-LIBS and MESBP-CF-LIBS has been performed by estimating the elemental concentration of a standard Vitallium alloy with 65% cobalt, 30% chromium and 5% molybdenum. In the MESBP-LIBS approach, we observed a reduction in distance value from 22 to 6, which represents a considerable improvement in the precision of quantitative elemental analysis.