Post-doctoral position in VUV photoionisation spectroscopy of free-radicals at Paris-Saclay University, Orsay, France

The ZEPHIRS consortium (ISMO, SOLEIL and ISM) proposes to combine the strengths of synchrotron and laser photoelectron spectroscopy for the identification of isomers/conformers of relevant reaction intermediates in atmospheric chemistry. By combining spectra with broad spectral coverage and moderate resolution, high-resolution spectra over small ranges, sophisticated ab initio calculations and dedicated models for large-amplitude motions in non-rigid molecules, novel information will be obtained on the (ro)vibronic structures of cations. These structural signatures have attractive analytical potential for reactions involving key systems such as peroxy radicals, Criegee intermediates and the C6H6 products of the propargyl reaction with itself. The results obtained will be transferred to the gas phase kinetics community for the improvement of atmospheric or combustion models.

The future candidate will participate in this project funded by the French National Research Agency (ZEPHIRS project) by working at the Institute of Molecular Sciences of Orsay on the VULCAIM set-up which couples a vacuum ultraviolet (VUV) laser with high spectral resolution and a photoelectron and/or mass spectrometer [1]. The main objective of the post-doctoral project, which is experimental in nature, will be to study the VUV photoionisation of gas phase radicals in order to obtain new data on the (ro)vibronic structure of their cations. To do this, the candidate will first work on the coupling of various radical sources with VULCAIM (electric discharge, pyrolysis, UV photolysis, fluorine reactor). He/she will carry out the acquisition of the spectra as well as their processing and simulation.

Research working environment
The ANR ZEPHIRS project involves three research teams: the SYSTEMAE team at the Institut des Sciences Moléculaires d'Orsay (ISMO) (see website:, the scientists of the DESIRS light line at SOLEIL and a researcher of the COMEX team at the Institut des Sciences Moléculaires de Bordeaux, who have a recognized expertise in photoelectron spectroscopy of radical species (see for instance refs. [2-6]). The post-doctoral work will take place entirely at ISMO, with Séverine Boyé-Péronne (Professor at the University of Paris-Saclay) and Bérenger Gans (Research Fellow at CNRS). The project will benefit from the ISMO's infrastructures as well as from the support of the laboratory's technical services (mechanical, instrumentation, electronic and computer services). The ZEKE photoionisation spectrometer is operational and is coupled to a high-resolution laser in the vacuum ultraviolet. Coupling with various radical sources is underway and will be pursued. The successful candidate will be likely to participate in experimental measurement campaigns conducted at the DESIRS line of the SOLEIL synchrotron depending on the success of the submitted beam time requests.

Deadline and funding conditions
The funding obtained from the ANR for this post-doctoral fellowship is aimed at a candidate who defended his/her thesis less than 2 years ago. The post-doctoral internship may start in March 2023 for a maximum duration of 13 months.

Candidate profile
Candidate with a thesis in physics or experimental chemistry-physics, with a thorough knowledge of molecular physics and optics/laser, and a strong interest in laboratory experiments and instrumentation. He/she should be able to work with concepts at the interface between chemistry, physics, astrophysics and planetology. Skills in programming and spectral simulations will be particularly appreciated.

Application procedure
A detailed CV, a cover letter, and the names and contact details of two potential referees, should be addressed to Séverine Boyé-Péronne ( and to Bérenger Gans (

[1] O.J. Harper et al., “Pulsed-Ramped-Field-Ionization ZEro-Kinetic-Energy PhotoElectron Spectroscopy: a methodological advance”, Phys. Chem. Chem. Phys. 24, 2777(2022)

[2] G. A. Garcia et al., “Synchrotron-based double imaging photoelectron/photoion coincidence spectroscopy of radicals produced in a flow tube: OH and OD”, J. Chem. Phys. 142, 164201 (2015)

[3] B. Gans et al., “Unveiling the Ionization Energy of the CN Radical”, J. Phys. Chem. Lett. 8, 4038 (2017)

[4] O.J. Harper et al., “Photoionization cross section of the NH2 free radical in the 11.1-15.7 eV energy range”, J. Phys. Chem. A 125, 2764-2769 (2021)
[5] N. L. Chen et al., “Photoionization spectroscopy of the SiH free radical in the vacuum-ultraviolet range”, J. Chem. Phys. 157, 014303(2022)

[6] N. L. Chen et al., “Unravelling the electronic structure of the silicon dimer using threshold photoelectron spectroscopy”, Mol. Phys. (2022)