Compositional quantification of binary ternary and quaternary metallic alloy-based coins using laser-induced breakdown spectroscopy

Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) is a suitable technique for the simultaneous determination of multiple elements present in any kind of sample and needs no other reference/standard materials; thus, it has potential applications in various sectors including industrial, geological, biological, etc. To present an example, we report a compositional quantification of two different metallic coins belonging to binary, ternary and quaternary alloy using this technique. Three samples (10 cents, 1 Euro—inner and outer part) of two metallic coins were considered for the present investigation. Time-evolution spectra were acquired between 0.5 and 5 µs with an interval of 0.5 µs. The plasma parameters, namely electron density and plasma temperature, were estimated for each time interval. An optimum temporal window for CF-LIBS analysis is identified from the temporal evolution studies of laser-induced plasma (LIP). The elemental concentrations of constituents were estimated using the CF-LIBS for all the studied samples and the results were compared with their certified concentration values. It was found that the results obtained by the CF-LIBS technique are in good agreement with the certified values in the optimum temporal window. Furthermore, principal component analysis (PCA) has been applied to discriminate/differentiate the various coins/samples studied in the present manuscript.