Self-calibrated Laser Induced Breakdown Spectroscopy for on-flight monitoring of Volcanic Ash.
Aya Taleb1, Marcella Dell’Aglio2, Rosalba Gaudiuso1, Daniela Mele3, Pierfrancesco Dellino3, Alessandro De Giacomo1,2
1Department of Chemistry, University of Bari “Aldo Moro”, Italy; 2Institute of Photonics and Nanotechnology (IFN) – CNR, Bari, Italy; 3Department of Earth and Geoenvironmental Sciences, University of Bari, Bari, Italy
Volcano monitoring and hazard assessment can be significantly improved by the real-time study of fine ash in volcanic plumes, which are composed of magma fragments released from volcano's craters during explosive eruptions. Numerous analytical techniques can be applied to obtain the chemical characterization of the juvenile pyroclastic material generated in volcanic plumes. Among them, the most appropriate and easily applied to advanced applications in extreme environments is Laser-Induced Breakdown Spectroscopy (LIBS) [1].
In the initial phase of our study, we present the elemental composition of suspended volcanic ash in air, obtained by a self-calibrated LIBS. Various sizes of volcanic ash samples collected from different sites were suspended in the air by laser-induced shockwaves in a dedicated chamber to replicate the conditions of dispersed volcanic ash in the atmosphere. Simultaneously, a parametric study was conducted to identify the optimal experimental settings for acquiring useful plasma emission spectra for each ash size. The quantitative analysis was then performed via Calibration-Free (CF) LIBS, which is based on the calculation of the spectral radiance of a uniform plasma in local thermodynamic equilibrium [2]. A significant improvement in our analysis method was the inclusion of a CF-LIBS software, which accounts intrinsically for self-absorption. This adjustment is crucial as self-absorption affects the spectral line intensities, leading to an underestimation of the elemental fraction. Another asset to our analytical technique was to deduce the instrument's response from the ash spectrum itself and avoid the necessity for standard calibration lamps. For that, an intensity calibration of the spectra based on the measurements of Fe lines intensities was employed in this work [3]. The results we obtained confirmed the feasibility of real-time elemental analysis measurements of volcanic ash, with a good degree of agreement with the literature composition. Moving forward, we are in the process of developing a portable instrument that can be integrated into drones for in-flight CF-LIBS measurements. New devices have been purchased, such as a small laser, spectrometers that cover a large spectral range and a whole optical system, with the lowest possible weight in order to be mounted on the drone.
Acknowledgement
This study was carried out within the RETURN Extended Partnership and received funding from the European Union Next-Generation EU (National Recovery and Resilience Plan–NRRP, Mission 4, Component 2, Investment 1.3–D.D. 1243 2-8-2022, PE0000005).
References
[1] A. De Giacomo, M. Dell'Aglio, Z. Salajková, E. Vaníčková, D. Mele, P. Dellino, Real-time analysis of the fine particles in volcanic plumes: A pilot study of Laser Induced Breakdown Spectroscopy with Calibration-Free approach (CF-LIBS), Journal of Volcanology and Geothermal Research, Volume 432.
[2] B. Bousquet, V. Gardette, V. Motto Ros, R. Gaudiuso, Marcella Dell'Aglio, Alessandro De Giacomo, Plasma excitation temperature obtained with Boltzmann plot method: Significance, precision, trueness and accuracy, Spectrochimica Acta Part B: Atomic Spectroscopy, Volume 204, 2023, 106686.
[3] A. Taleb, M. Dell’Aglio, R. Gaudiuso, D. Mele, P. Dellino, A. De Giacomo, Self-Calibrated Laser-Induced Breakdown Spectroscopy for the Quantitative Elemental Analysis of Suspended Volcanic Ash, Applied Spectroscopy, 2024, 0(0).
FROM EARTH TO SPACE GEOLOGY, THE APPLICATION OF LASER-INDUCED BREAKDOWN SPECTROSCOPY
Jakub Buday1,2, Daniel Holub3, Pavel Pořízka1,2,4, Jozef Kaiser1,2,4
1Central European Institute of Technology, Brno University of Technology, Czech Republic; 2Faculty of Mechanical Engineering, Brno University of Technology, Technická 2896, 616 69, Brno, Czech Republic; 3European Space Resources Innovation Centre (ESRIC), 41 Rue du Brill, Luxemburg; 4Lightigo s.r.o., Renneská třída 329/13, 639 00 Brno, Czech Republic
Laser-Induced Breakdown Spectroscopy (LIBS) is an Optical Emission Spectroscopy (OES) technique that relies on the optical analysis of laser-induced plasma (LIP) generated on the surface of a sample. Thanks to its versatility, rapid multielement detection capabilities, and minimal sample preparation requirements, LIBS has found broad application in a range of complex research fields, including geology [1].
The use of LIBS in geological studies typically focuses on two primary areas: qualitative and quantitative analysis. In qualitative applications, the method is employed to determine elemental compositions or to identify and classify different sample types. Achieving reliable classification results requires the development of a comprehensive and well-structured analytical methodology. On the other hand, quantitative analysis involves determining the precise elemental concentrations within unknown samples, which demands rigorous calibration and validation procedures [2].
Both qualitative and quantitative LIBS approaches are highly relevant in terrestrial as well as extraterrestrial geology. In the context of the present research, applications range from building extensive mineralogical libraries based on terrestrial samples to performing quantitative analyses of regolith simulants or meteorite specimens. This work proposes and develops methodologies tailored for these diverse analytical tasks, emphasizing their adaptability for specific geological applications or for broader use across related scientific disciplines.
Acknowledgments
This research was financially supported by the FSI-S-23-8389, and the Czech Science Foundation (23-05186K).
References
[1] J. Buday, J. Cempírek, J. Výravský, P. Pořízka, J. Kaiser, Robust Mineralogy Analysis Utilizing Laser-Induced Breakdown Spectroscopy and Dispersive X-Ray Spectroscopy, in: 2024 IEEE Sensors Applications Symposium, SAS 2024 - Proceedings, Institute of Electrical and Electronics Engineers Inc., 2024. https://doi.org/10.1109/SAS60918.2024.10636561.
[2] P. Pořízka, A. Demidov, J. Kaiser, J. Keivanian, I. Gornushkin, U. Panne, J. Riedel, Laser-induced breakdown spectroscopy for in situ qualitative and quantitative analysis of mineral ores, in: Spectrochim Acta Part B At Spectrosc, Elsevier, 2014: pp. 155–163. https://doi.org/10.1016/j.sab.2014.08.027.
Quasi-nondestructive method for estimating the compressive strength of concrete using laser-induced breakdown spectroscopy
Shuzo ETO, Taku Otsuka
Central Research Institute of Electric Power Industry
We propose a new method for non-destructive estimation of concrete compressive strength. This method is based on Laser-Induced Breakdown Spectroscopy (LIBS) and multivariate analysis, which allows estimation of compressive strength independent of coarse aggregate distribution. Concrete compressive strength is an important parameter for quality control and durability assessment of concrete. Typically, compressive strength is determined by an uniaxial compression testing. Conventional non-destructive methods using elastic waves have the problem that the measured values vary depending on the measurement location because the wave propagation path changes due to the distribution of coarse aggregates. The method proposed in this study extracts the mortar spectrum by using LIBS to estimate the compressive strength. This method is based on the correlation between the hardness of the mortar and the emission intensity of the spectrum. Principal component analysis and partial least squares regression are used to extract the mortar spectral data from the measured LIBS data and to estimate the compressive strength. This approach is robust to spectral noise. The compressive strength estimated by the proposed method was in agreement with the results of actual compressive strength tests. It is expected that the proposed method will enable rapid, nondestructive and remote measurement of the compressive strength of actual concrete structures in the future.
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