Institut des Sciences Moléculaires d'Orsay



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Accueil > Équipes scientifiques > Systèmes Moléculaires, Astrophysique et Environnement (SYSTEMAE) > Offres de stages, thèses et post-docs > High-resolution photoelectron spectroscopy of free radicals

M2 internship

High-resolution photoelectron spectroscopy of free radicals

M2 or PhD

The complex photophysics occurring in astrophysical media are mainly induced by galactic and solar fluxes in the ultra violet (UV) and vacuum ultra violet (VUV) ranges. In these spectral domains, the photons are energetic enough to lead to destructive relaxation pathways, such as ionization, fragmentation, dissociative ionization, … These processes give rise to highly reactive species which in turn participate to the molecular complexity growth of these media. In fundamental physics, VUV-induced photophysics are still exploratory and allow to unveil very specific quantum structures of unstable species such as free radicals or molecular cations in diverse rovibronic quantum states (from ground state to high Rydberg states).
This internship will be devoted to the study of free radical (CN, CH, C2H, NH, …) photoionization processes using a photoelectron spectroscopy method recently developed in our team (Pulsed-Ramped-Field Ionization Zero Kinetic Energy PhotoElectron Spectroscopy, PRFI-ZEKE PES). This technique allows the recording of photoionizing transitions of species by selecting very high Rydberg states thanks to a narrow bandwidth tunable VUV laser and well controlled pulsed electric fields. These measurements will be performed on the recently-built VULCAIM setup (O. J. Harper, PhD thesis, Université Paris- Saclay, 2020) which couples a high-resolution VUV laser (unique in France), a skimmed molecular beam, and a photoelectron spectrometer.

In parallel, similar measurements at medium resolution will be performed on the DESIRS beamline of the SOLEIL synchrotron using the Threshold PhotoElectron Spectroscopy (TPES) technique. The experimental results will be confronted to ab initio calculations through national and international collaborations.
The intern will have to get familiar with diverse vacuum, laser optics, electronics, and spectroscopy techniques in order to handle the VULCAIM setup and, in parallel, to participate to synchrotron experimental campaign. He/she will participate to the acquisition and the treatment of data. This work would be ideally pursued through a PhD thesis project funded by the EDOM doctoral school.
The team (S. Boyé-Péronne & B. Gans) published about 20 papers on this topic in the last three years ( and has just obtained a grant from ANR (ZEPHIRS project, led by ISMO) in collaboration with the DESIRS beamline of the SOLEIL synchrotron and the ISM lab of Bordeaux.
This grant will allow new experimental developments and the recruitment of a post- doctoral researcher to strengthen the team. The intern will thus benefit from a stimulating environment to progress in his research project.
The candidates would ideally :
- have good knowledge in molecular physics and optics, -be motivated by experimental research, and
- be in the perspective of doing a PhD thesis.

Voir en ligne : Astrophysique et édifices moléculaires