Stage de niveau M1, L3 dans l’équipe SYSTEMAE
Diffuse interstellar bands (DIBs) have been observed in the visible and near-infrared range (400-1500 nm) in interstellar extinction curves for over a century. The only identified carrier is C₆₀⁺, but it accounts for only a handful of DIBs among more than 600 cataloged. The identity of the molecules responsible for the other absorptions remains unknown. A plausible hypothesis is that these DIBs are caused by molecular ions that are difficult to detect due to their low density in the laboratory. Cavity ring-down spectroscopy (CRDS) overcomes these limitations by using absorption paths of several kilometers, where the escape rate of photons from the optical cavity reflects the absorption cross section of the absorber.
In this internship, electronic spectra of molecular ions will be obtained using CRDS at the exit of a supersonic expansion coupled with an electrical discharge. These laboratory data will be directly compared with astronomical data recorded by ground-based and space telescopes.
Location: Institut des Sciences Moléculaires d’Orsay (ISMO), Bât. 520, Université Paris-Saclay, Orsay
Contact: Ugo Jacovella