In the micro-laser-induced breakdown spectroscopy field, when the laser ablated crater on the surface of the sample is less than 10 mu m, it is difficult to detect the plasma emission line because of short lifetime of excited plasma, and simultaneous quantitative analysis of multiple elements is rarely reported. In this paper, a picosecond LIBS micro-area analysis scheme is proposed. Compared with the femtosecond laser micro-area analysis system, this scheme is more mature and reliable, and is more beneficial to engineering applications. In addition, in this study, the effect of the number of laser pulses on the crater morphology was studied. It was observed that a certain crater depth would have an enhancement effect on the signal, and by controlling the laser energy, a crater less than the diffraction limit was obtained. Moreover, a multielement simultaneous analysis on a set of molybdenum-copper stainless steel samples containing 40%-70% iron was performed when the ablated crater had an outer diameter of approximately 5 mu m and an inner diameter of approximately 3 mu m. By accumulating spectral intensity, background removal, and abnormal point processing, the calibration results for the eight elements of Mn, Cr, Ni, Cu, Ti, V, Nb and Al were not less than 0.95 using the basic calibration method. Among them, the calibration results for Ni, Cu, V, Nb, Al elements are all higher than 0.99 and the detection limits of the obtained elements range from 0.04% to 1.8%.

This study is published on MICROCHEMICAL JOURNAL 158(2020):1-8.