Semi quantitative Elemental Analysis ofVolcanic Ashes from Populations Surroundingthe Tungurahua Volcano of the Eruptive Period2008-2010, Using the LIBS Spectroscopy(Laser-Induced Breakdown Spectroscopy)

D.M. DÍAZ PACE; G. VÁZQUEZ; C. COSTA VERA; S. HIDALGO

Congreso; 10th Euro-Mediterranean Symposium on Laser-Induced Breakdown Spectroscopy; 2019

comThe geochemical characterization of volcanic ash is of great scientific interest since, itallows to clarify the mechanisms that dominate the behavior of the eruptions of the volcano,and to know in more detail the products generated and processes involved in each eruptivephase, in order to distinguish changes in their activity patterns. This work was carried out inthe Spectroscopy laboratory of the Physics Department of the National Polytechnic School,applying the Laser-induced Breakdown Spectroscopy (LIBS) technique to determine theelemental chemical composition in 18 ash samples from the Tungurahua volcano collectedfrom nearby populations. In this work we propose suitable preparation methods of volcanicash to guarantee the homogeneity of the sample. Qualitative and quantitative elementalanalysis was performed in two different environments for the taking of spectra, common airand atmosphere saturated with argon. For the quantitative analysis of the elements present,Calibration-free LIBS (CF-LIBS) is used, a technique used to determine the elementalcomposition of an arbitrary sample using statistical distributions of Saha-Boltzmann andBoltzmann. The instrumental response function of the LIBS equipment of the EPN wasdetermined, adjusting each of the intensity values measured in a LIBS spectrum by a factorthat represents the relative response of the instrument in that value. This correction wasused for the analyzed samples, in combination with software appropriate for the CF-LIBSanalysis, in which the corresponding Saha-Boltzmann and Boltzmann graphs are analyzed,thus quantifying the temperature, and the electronic density of the plasma.