Experimental designs in LIBS
| Autor: | Sirven, Jb., El Rakwe, M. |
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| Přispěvatelé: | amplexor, amplexor, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA) |
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: | |
| Zdroj: | 9th Euro-Mediterranean Symposium on LIBS / Colloquium Spectroscopicum Internationale XL 9th Euro-Mediterranean Symposium on LIBS / Colloquium Spectroscopicum Internationale XL, Jun 2017, Pisa, Italy |
| Popis: | International audience; Like for any analytical technique, LIBS measurements involve many experimental parameters which can be catego-rized in two groups. The first one includes instrumental parameters, i.e. those that one is led to select when designing a LIBS system, related to the laser (wavelength, pulse duration, repetition rate), the beam focusing optical system, the plasma light collection setup, the spectrometer and the detector. The second group encompasses parameters of the measurement, i.e. the ones the user has to adjust when analyzing a sample pulse energy, lens-to-sample distance (LTSD), number of laser shots, nature and pressure of the ambient medium, time gate delay and width of the detection system. Among all those parameters, it is important to underline that only that of laser ablation can be freely chosen by the user. All other ones are driven by the sample nature and by the plasma properties. Another important thing is that in general, parameters are coupled and non-linearly influence the LIBS signal. As an example, the optimum gate delay for maximum signal-to-noise ratio depends on the pulse energy, and the signal-to-noise ratio is not linear with the gate delay. Therefore, optimization of a LIBS measurement is not straightforward, and parametric studies often implemented are not sufficient to take into account those coupling and non-linearities. Finally, the optimization also depends on the analytical objective and must consider the constraints of the application.Experimental designs are efficient tools for screening and optimization of influent parameters of a measurement, us-ing a minimum number of experimental trials. Although they are broadly used in many fields of analytical chemistry, they are not so widespread in the LIBS community. In this talk, we will first review the applications of experimental designs in LIBS, generally focused on empirical optimization of an analytical response. Then, we will show how experimental designs can be useful to address other issues such as the investigation of the relationship between physi-cal and analytical features of the measurement, the choice of the best analytical line, and the evaluation of the robustness of a LIBS system. |
| Databáze: | OpenAIRE |
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