Origin and Evolution of Cosmic PAHs: Tracing Molecular Content of Dust Analogs, Meteorites and Asteroids

Soutenance de HDR de Hassan Sabbah (Salle de Conférence)

Résumé de la HDR

Large carbonaceous molecules such as polycyclic aromatic hydrocarbons (PAHs) and fullerenes are prevalent in astrophysical environments.They play a significant role in the physics and chemistry of regions where stars and planets form. The investigation into the formation of specific molecules within these families, particularly in the hot and dense envelopes of evolved stars, has spurred numerous research efforts to synthesize cosmic dust analogues using various techniques. Additionally, the analysis of extraterrestrial materials, such as meteorites and samples returned from missions to asteroids, holds promise for providing further insights into the origin and evolution of these molecules.

After introducing the astrophysical context, I will present our experimental setup, AROMA (Astrochemistry Research of Organics with Molecular Analyzer). It serves as a pivotal tool for probing PAHs, carbon clusters, and fullerenes in both cosmic dust analogs and meteorite samples. The setup comprises a laser desorption ionization source and a segmented linear quadrupole ion trap connected to an orthogonal time-of-flight mass spectrometer. I will notably mention our results on cosmic dust analogs generated by the Stardust machine and through in-flame combustion soot. I will then discuss our findings regarding the analysis of meteorites such as Murchison and Allende (both carbonaceous chondrites), along with Almahata Sitta, a ureilite meteorite. Finally, I will present new perspectives in our research through the analysis of samples returned from missions like Hayabusa2. Additionally, I will introduce our project to analyze a large number of carbonaceous chondrite samples to better understand the distribution of carbonaceous molecules in these objects. I will conclude by introducing the development of a new instrument that integrates very high-resolution mass spectrometry and microprobe two-step laser desorption-ionization.