Determination of the Gold Alloys Composition by Laser-Induced Plasma Spectroscopy Using an Algorithm for Matching Experimental and Calculated Values of Electron Number Density

Laser-induced breakdown spectroscopy (LIBS) was applied for qualitative and quantitative analysis of gold alloys. A frequency double-pulsed Nd:YAG laser was used to generate plasma on the surface of gold alloys. The plasma temperatures of gold and copper were calculated using Boltzmann plots whereas electron number densities were determined via Saha–Boltzmann equations. The effect of self-absorption in the laser-induced emission spectra was evaluated for correction in the intensity of spectral lines. By combining electron number density conservation approach (ENDC) with LIBS, an algorithm for gold alloys composition determination was derived by matching the theoretically derived ratios of the number densities and the experimentally obtained ratios of the number densities extracted from LIBS spectra. The results of ENDC–-LIBS approach were compared with those estimated by a conventional calibration-free LIBS approach and other established analytical technique energy dispersive X-ray. The results clearly demonstrated that ENDC–LIBS methodology appeared to be very promising for analysis of LIBS spectra of gold alloys.