Study of carbonaceous nanograins-water interactions in the era of James Webb Space Telescope. – (Arya M Nair / Thesis / LCAR), 29/11/2024, 14H

PhD defense

Arya M Nair FeRMI, Salle de conférence 3R4

Composition du jury:

• Jean Hugues Fillion (Sorbonne Université)
• Jennifer Noble (Aix-Marseille Université)
• Franck Le Petit (Observatoire de Paris)
• Aude Simon (Université Toulouse III)
• Christine Joblin (Université Toulouse III)
• Sébastien Zamith (Université Toulouse III)

Abstract:
The aromatic infrared bands (AIBs) observed in the interstellar medium is attributed to the emission from a group of molecules called Polycyclic Aromatic Hydrocarbons (PAHs). In the dense clouds that are shielded from UV radiations, interstellar dust is coated by ices in which water plays a key role. This PhD thesis in the field of laboratory astrophysics aims to study of interaction of water with these PAHs under controlled physical conditions.

More precisely, positively charged mixed PAH (here pyrene)-water clusters are produced in a cryogenic gas aggregation source prior to thermalization at 25K. The mass selected cluster undergo collisions with inert gases and the products are analyzed using time-of-flight mass spectrometry. Experiments were also performed on deuterated system to understand H/D exchange mechanism.

The studies provide information regarding the dissociation energy and hence helps to characterize the structure of the cluster. The molecular data obatined could be used to model these interactions in star- and planet-forming regions.