Elemental analysis of copper alloys with laser-ablation spark-induced breakdown spectroscopy based on a fiber laser operated at 30 kHz pulse repetition rate

Abstract

Laser-ablation spark-induced breakdown spectroscopy (LA-SIBS) based on a fiber laser operated at 30 kHz pulse repetition rate was first developed to realize sensitive elemental analysis of minor elements in copper alloys. The characteristics of the spark discharge operated at 30 kHz repetition rate and the effects of discharge voltage as well as the capacitance of the energy storage capacitor on the signal intensities of different atomic lines and their signal-to-background ratios were studied. The calibration curves of lead, iron and aluminum in copper alloys have been generated using a compact fiber spectrometer to analyze the spectra. Selecting Pb I 368.35 nm, Fe I 358.12 nm and Al I 396.15 nm analytical lines, the detection limits of lead, iron and aluminum in copper alloys were determined to be 1309, 1022 and 106 ppm when the sample was only ablated by a fiber laser with 0.6 mJ pulse energy. With the assistance of the spark discharge, these detection limits have been improved to be 240, 113 and 30 ppm, demonstrating a 3–9 fold enhancement of the detection limit under current experimental conditions. This work demonstrates that the spark discharge can be used to improve the analytical sensitivity of a portable laser-induced breakdown spectroscopic system consisting of a fiber laser and a fiber spectrometer. The portable LA-SIBS system based on a fiber laser and fiber spectrometer will be helpful to realize more sensitive elemental analysis for different solid samples than a portable LIBS system that consists of the same fiber laser and the same fiber spectrometer.