Application of Laser Ablation–Laser Induced Fluorescence Spectroscopy to Analysis of Steel

—Detection of Low Phosphorus in Steel—

Abstract

Quantitative detection of phosphorus in steel by Laser ablation–laser induced fluorescence spectrometry has been studied. Solid steel samples were irradiated by pulsed Nd:YAG laser (ablation laser) to generate atomic vapor, which was then illuminated by the probe laser. Laser induced fluorescence spectrum of phosphorus with the highest selectivity was obtained with excitation at 255.49 nm among transitions of atomic phosphorus in 253–256 nm. Dependences of fluorescence intensity on pulse energies of ablation laser and probe laser were investigated. Fluorescence intensity was found to be logarithmically proportional to the ablation laser pulse energy with the slope of 3.2–3.3. Fluorescence intensities were in a good linear correlation with contents of phosphorus in steel samples in a range of 37–350 μg/g. Relative standard deviation were 5.6 and 12.8% at 72 and 170 μg/g of phosphorus, respectively.