Investigation of excitation interference in laser-induced breakdown spectroscopy assisted with laser-induced fluorescence for chromium determination in low-alloy steels

Chromium determination in steels suffered from excitation interference in laser-induced breakdown spectroscopy assisted with laser-induced fluorescence (LIBS-LIF). In this work, excitation interference between target chromium atoms and matrix iron atoms was investigated in detail. Relative absorption strength (RAS) of chromium and iron was mathematically deduced and utilized to estimate the excitation interference theoretically. Standard calibration curves of LIBS and LIBS-LIF for chromium determination in low-alloy steels were experimentally established. The chromium line 359.35 nm with less interference in the RAS map provided better analytical performance (slope of 1.99x10(5) counts/wt%, detection limit of 8.64 mu g g(-1), R-2 of 0.992, average RSD of 2.89%), in accordance with the theoretical estimation. This work realized sensitive and accurate determination of trace chromium in low-alloy steels, even influenced by excitation interference. An effective estimation method was provided for evaluating excitation interference to choose a suitable excitation line.