Steel analysis with laser-induced breakdown spectrometry in the vacuum ultraviolet

Laser-induced breakdown spectrometry (LIBS) with multiple pulse excitation has been applied for the multielemental analysis of steel samples in the vacuum ultraviolet. The emission of the induced plasma was coupled into a Paschen-Runge spectrometer equipped with photomultipliers linked to high-speed multichannel signal electronics. Time-resolved signal evaluation yields a significantly improved signal-to-noise ratio for the plasma emission periods after a multipulse excitation. Reference materials for low-alloy steel grades were used to calibrate the measurements. The investigations concentrated on the light elements phosphorus, sulfur, and carbon using emission wavelengths in the range from 178.28 nm to 193.09 nm. For the first time, limits of detection below 10 mu g/g were achieved for the light elements phosphorus, sulfur, and carbon using LIBS. With these results the basis is established for future on-line applications of LIBS in the steel industry.