Acoustic Spectroscopy of Laser-Induced Plasma

• Autores: Markéta Bosáková
• Directores de la Tesis: Javier Moros Portolés (dir. tes.), José Javier Laserna Vázquez (dir. tes.), Karel Novotný (dir. tes.)
• Lectura: En la Masaryk University ( Chequia ) en 2025
• Idioma: inglés
• Tribunal Calificador de la Tesis: Viktor Kanický (presid.), Francisco Javier Fortes Román (secret.), Pablo Purohit Pacheco (voc.), José Miguel Vadillo Pérez (voc.), Přemysl Lubal (voc.)
• Programa de doctorado: Programa de Doctorado en Química y Tecnologías Químicas. Materiales y Nanotecnología por la Universidad de Málaga
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• Resumen

  • This dissertation presents a novel strategy for the incorporation of acoustic signals in laser-induced breakdown spectroscopy. In recent years, there has been an increasing focus on the fusion of diverse analytical approaches to enhance qualitative and quantitative analyses. A notable approach involves the utilization of the acoustic signal generated by the laser-matter interaction between the sample and the laser pulse, a technique that has been employed by the Mars 2020 mission rover Perseverance. This dissertation aims to explicate several acoustic-spectroscopic phenomena that establish novel, systematic scientific foundations for the final complementarity of these methods. The initial section is dedicated to the examination of the influence of the physicochemical properties of the samples on the acoustic and emission signals, with additional consideration of the impact of the positioning of the acoustic receiver, in this case, a commercially available condenser microphone.

    The subsequent section explores the practical application of this knowledge, with a particular focus on the field of geology, emphasizing the domain of chemical acoustic-emission mapping. It has been demonstrated that the acoustic signal provides highly accurate and precise distribution maps with respect to the sample composition, complementing the chemical maps obtained from emission spectra.

    In the third part, the focus was on the influence of instrumentation on acoustic-emission signal. The study investigated the influence of the ablation source wavelength and different types of microphones, with a particular emphasis on MEMS microphones (microelectro- mechanical systems). These microphones are characterized by good compactness, robustness, small size and a wide choice according to the required acoustic-mechanical properties. The section was further expanded to consider the acoustic-emission analysis of nano- and microlayers, where the acoustic signal yielded results analogous to those of the emission signal.

    In the final section, the focus was directed towards the examination of the effects of altering atmospheric conditions, with the primary objective being the imitation of the atmospheric conditions that prevail on Mars. This approach was undertaken to achieve a more accurate approximation of the real conditions in which the Perseverance rover is currently operating. This involves monitoring variations in temperature (-40 to 20°C), ambient gas pressure modifications (1 to 30 mbar CO2) and the composition of the surrounding atmosphere (Ar, Air, N2, CO2).

    The four sections of this dissertation constitute the pioneering systematic acoustic-emission study of its kind, thereby providing invaluable insights for the future application of the LIBS-LIPAc (Laser-Induced Plasma Spectroscopy & Laser- Induced Plasma Acoustic) method in real-world research in harsh and extraterrestrial environments.