On-line determination of nanometric and sub-micrometric particle physicochemical characteristics using spectral imaging-aided Laser-Induced Breakdown Spectroscopy coupled with a Scanning Mobility Particle Sizer

Abstract

International audienceLaser-Induced Breakdown Spectroscopy has been employed to detect sodium chloride and metallic particles with sizes ranging from 40 nm up to 1 µm produced by two different particle generators. The Laser-Induced Breakdown Spectroscopy technique combined with a Scanning Mobility Particle Sizer was evaluated as a potential candidate for workplace surveillance in industries producing nanoparticle-based materials. Though research is still currently under way to secure nanoparticle production processes, the risk of accidental release is not to be neglected. Consequently, there is an urgent need for the manufacturers to have at their command a tool enabling leak detection in-situ and in real time so as to protect workers from potential exposure. In this context, experiments dedicated to laser-induced plasma particle interaction were performed. To begin with, spectral images of the laser-induced plasma vaporizing particles were recorded to visualize the spatio-temporal evolution of the atomized matter and to infer the best recording parameters for Laser-Induced Breakdown Spectroscopy analytical purposes, taking into account our experimental set-up specificity. Then, on this basis, time-resolved spectroscopic measurements were performed to make a first assumption of the Laser-Induced Breakdown Spectroscopy potentialities. Particle size dependency on the LIBS signal was examined. Repeatability and limits of detection were assessed and discussed. All the experiments carried out with low particle concentrations point out the high time delays corresponding to the Laser-Induced Breakdown Spectroscopy signal emergence. Plasma temperature temporal evolution was found to be a key parameter to explain this peculiarity inherent to laser / plasma / particle interaction

New Approach for Near-Real-Time Measurement of Elemental Composition of Aerosol Using Laser-Induced Breakdown Spectroscopy

“…The overall repeatability (except for Cd) of our system was better compared to reported values for FSA LIBS techniques that typically have repeatability in the range 25%-42% (Cheng 2003;Lithgow et al 2004;Amodeo et al 2009). …”

“…Matrix effects, i.e., artifacts introduced by the presence of elements other than the analyte, can also degrade the accuracy of LIBS measurements. Further, the repeatability or precision of aerosol measurement typically has been poor (Cheng 2003;Lithgow et al 2004;Amodeo et al 2009). Reliable calibration of aerosol LIBS systems is another key factor that has not been sufficiently addressed by the previous studies.…”

Measurement of elemental concentration of aerosols using spark emission spectroscopy

“…The relative standard deviation (RSD) at various mass loadings was in the range of 2-15% which is much better compared to LIBS or spark plasma systems employing free stream approach for aerosol analysis. [42][43][44] Higher RSDs, typically in the range of 10-20%, have been reported for filter-based LIBS analyses. 45 The repeatability of measurements is also better than that obtained using laserinduced plasma in our earlier study.…”

Sampling considerations when analyzing micrometric-sized particles in a liquid jet using laser induced breakdown spectroscopy

“…Such procedure was motivated bearing in mind that the plasma volume tends to enlarge when increasing the energy. Such enlargement results in a much slower cooling speed thereby temporally shifting the time delays at which the recording of the given line of an element is optimized [18,19]. The obtained results are presented on figure 4.…”

“…This maximum sampled volume may be approximated multiplying the liquid jet thickness (L  1 mm) by the roughly estimated laser-jet interaction surface S 0 (6500 µm 2 ). The so calculated volume MV S (possible maximum sampling volume) equaling 10 -6 cm 3 proves to be much larger than the sampling volume V S which tends to saturate beyond [15][16][17][18][19][20] mJ with values of around 6 10 -8 cm 3 (V S / MV S << 1). Thus, the estimations of the sampling volume V S and depth h and their comparison with a possible maximum sampling volume MV S and the liquid jet thickness L respectively make it clear that the area sampled by the laser remains confined near the liquid jet surface.…”