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Silver jewelry microanalysis with dual-pulse laser-induced breakdown spectroscopy: 266 + 1064 nm wavelength combination.

Orthogonal dual-wavelength dual-pulse laser-induced breakdown spectroscopy (ODWDP-LIBS) with 266+1064  nm wavelength combination was applied to realize silver jewelry microanalysis with enhanced sensitivity and minimal sample ablation. In this technique, the 266 nm laser with low pulse energy was selected as ablation laser and the time-delayed 1064 nm laser with moderate pulse energy was selected as reheating laser to enhance plasma emission. Significant signal enhancement was achieved under the excitation of the reheating laser without increasing mass ablation which was only determined by the ablation laser. Internal standard method was applied to realize quantitative analysis of copper impurity in silver jewelry samples. The calibration curve was built, and the limit of detection of copper in silver matrix was determined to be 37.4 ppm when the crater diameter was controlled at 6.5 μm. This technique is especially useful for microanalysis of precious samples due to the property of less sample ablation in comparison with single-pulse laser-induced breakdown spectroscopy (SP-LIBS) under the same analytical sensitivity.