Laser-induced breakdown spectroscopy of liquid-droplet aerosols using nanosecond pulses
A.A. Ilyin1,2, A.Yu. Mayor1,2, Yu.S. Tolstogonova1,2, V.V. Lisitsa2
1Far Eastern Federal University, Vladivostok, Russia
2Institute of Automation and Control Prosesses Far Easten Branch of the Russian Academy of Science, Vladivostok, Russia
Keywords: laser plasma, aqueous aerosol, electron density, emission line, laser-induced breakdown spectroscopy
Abstract
Laser-induced plasma diagnostics in aerosols is complicated by plasma inhomogeneity. In this work, the electron density of laser-induced plasma was evaluated based on Ba II 455.4, Na I 589, Al I 396.2, Ca II 393.4 and Fe I 542.4 nm emission lines for the case of using equipment on mobile carriers. It was found that the electron density is minimal for the Ba II line and maximal for the Na I line; the difference in the values attained almost an order of magnitude, which was attributed to differences in the diffusion lengths of the elements. It was experimentally shown that the plasma electron temperature weakly depends on time in the 2-4 ms range at exposure times of 40 and 150 ms. It was confirmed that recombination pumping of the upper levels of transitions under study did not significantly affect the intensity of the analytical lines. Based on the analysis of the rate constants of excitation from the ground state, the limit of detection was found to be the worst for Al I 396.2 nm line. The results of the work can be used in emission spectral analysis of aerosols.
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