Postdoc Position on Low Temperature Kinetics at Rennes

Two year postdoc position to work at the Institute of Physics, Rennes, France, on low temperature reaction kinetics

Applications are invited for a postdoctoral research associate position at the Institute of Physics Rennes (IPR) within the Molecular Physics Department to conduct experimental research in fundamental chemical physics and reaction kinetics, with particular application to laboratory astrophysics and astrochemistry, as well as to atmospheric science. The position is jointly funded by a Rennes Metropole research chair (P.I.  François Lique), the Brittany Region and the University of Rennes 1, and is associated with two European Research Council projects: COLLEXISM (P.I. François Lique and CRESUCHIRP (P.I. Ian Sims – as well as the ongoing CRESUSOL project (P.I.s Ludovic Biennier and Sébastien Le Picard – [1]).

The research project

We aim to investigate the low temperature kinetics of formation of complexes containing water [see e.g. 2], and to determine quantitative product branching ratios for elementary bimolecular reactions at low temperatures [see 3 for references]. The CRESU (Reaction Kinetics in Uniform Supersonic Flow) technique, a speciality of the Rennes team [3], will be used to provide a gas phase environment at extremely low temperatures (down to 10 K) which can operate under highly supersaturated conditions. Two main diagnostics will be employed to follow the processes under study: the CRESUSOL instrument [1] which combines a CRESU reactor and a time-of-flight mass spectrometer with VUV photoionization and photoelectron-photoion coincidence detection, and the CRESUCHIRP apparatus which associates newly constructed high performance chirped-pulse mm-wave rotational spectrometers [4,5] with CRESU flows to detect transient species such as reaction products by the CPUF (chirped pulse in uniform flow) technique [6]. The CRESUSOL instrument is mobile, and experiments will be carried out on the DESIRS VUV beamline at the SOLEIL synchrotron in Paris. The postdoc will also lead an upgrade of the detection capabilities of the instrument with preliminary measurements possible using fixed wavelength VUV sources at the IPR. In parallel, the postdoc will participate in the CRESUCHIRP project at the IPR to measure quantitatively the branching ratios of neutral-neutral reactions down to very low temperatures (as low as 10 K), of great interest for astrochemistry. Certain reactions can be studied in a complementary fashion by both techniques, providing a unique opportunity to be trained in a wide range of state-of-the-art experimental chemical physics methods.

Research training environment

The postdoc will benefit from strong interactions with the theory group of François Lique as well as an exceptional technical environment constructed within the framework of the CRESUCHIRP and CRESUSOL projects, both in terms of dedicated and high-quality laboratory space as well as custom built high performance scientific instruments. The project will be undertaken within the intellectually stimulating context of the Rennes Laboratory Astrophysics group ( within the Molecular Physics Department of the Institute of Physics Rennes, situated in the attractive and vibrant capital of the Brittany region of France. The group benefits from strong international collaborations, including the QUADMARTS International Research Network ( which brings together French and US partners working on the QUAntitative Detection of Molecular And Radical Trace Species, along with associated laboratories across Europe.

Candidate profile

Candidates should possess a PhD in experimental physics or physical chemistry, and experience in the use of microwave spectroscopy, mass spectrometry, ion optics, pulsed lasers, vacuum and gas handling techniques and computer interfacing and programming is highly desirable. Experience in research supervision (e.g. undergraduate internships) would also be advantageous. A working knowledge of English is essential to be able to interact effectively with the multinational host team. French language lessons can be arranged if desired.

Procedure for candidatures

The position is available starting in September-October 2021 (or eventually up until January 2022) for a period of 12 months, renewable for a further 12 months by mutual agreement. Candidates must not have spent more than 12 months in France over the past three years. 

Inquires and applications, including a detailed CV and list of publications, an accompanying letter, and the names and contact details of two (or three if possible) potential referees, should be addressed to Prof. Ian Sims (, and copied also to Dr. Ludovic Biennier ( Applications will be considered as they are received.

Keywords: chemical physics, molecular physics, physical chemistry, molecular astrophysics, experimental astrochemistry, laboratory astrophysics, atmospheric science, photoionisation mass spectrometry, chirped pulse Fourier transform mm-wave spectroscopy, CRESU, water clusters, low temperature reaction kinetics, product branching ratios, elementary reactions.


1.  O. Durif, M. Capron, J. P. Messinger, A. Benidar, L. Biennier, J. Bourgalais, A. Canosa, J. Courbe, G. A. Garcia, J. F. Gil, L. Nahon, M. Okumura, L. Rutkowski, I. R. Sims, J. Thiévin, and S. D. Le Picard, A new instrument for kinetics and branching ratio studies of gas phase collisional processes at very low temperatures, Rev. Sci. Instrum. 92 (2021), 014102

2.  J. Bourgalais, V. Roussel, M. Capron, A. Benidar, A. W. Jasper, S. J. Klippenstein, L. Biennier, and S. D. Le Picard, Low Temperature Kinetics of the First Steps of Water Cluster Formation, Phys. Rev. Lett. 116 (2016), 113401

3.  I. R. Cooke and I. R. Sims, Experimental Studies of Gas-Phase Reactivity in Relation to Complex Organic Molecules in Star-Forming Regions, ACS Earth Space Chem. 3 (2019), 1109-1134

4.  B. M. Hays, T. Guillaume, T. S. Hearne, I. R. Cooke, D. Gupta, O. Abdelkader Khedaoui, S. D. Le Picard, and I. R. Sims, Design and performance of an E-band chirped pulse spectrometer for kinetics applications: OCS – He pressure broadening, J. Quant. Spectrosc. Radiat. Transfer 250 (2020), 107001

5.  T. S. Hearne, O. Abdelkader Khedaoui, B. M. Hays, T. Guillaume, and I. R. Sims, A novel Ka-band chirped-pulse spectrometer used in the determination of pressure broadening coefficients of astrochemical molecules, J. Chem. Phys. 153 (2020), 084201

6.  C. Abeysekera, B. Joalland, N. Ariyasingha, L. N. Zack, I. R. Sims, R. W. Field, and A. G. Suits, Product Branching in the Low Temperature Reaction of CN with Propyne by Chirped-Pulse Microwave Spectroscopy in a Uniform Supersonic Flow, J. Phys. Chem. Lett. 6 (2015), 1599-1604

Ian Sims

Institut de Physique de Rennes
Département Physique Moléculaire
UMR 6251 du CNRS – Université de Rennes 1 
Bat. 11c, Campus de Beaulieu
263 Avenue du Général Leclerc
tel.: +33 2 23 23 69 18
fax.: +33 2 23 23 67 86


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