Collisions Moléculaires en Milieux Extrêmes (COMEX)

Group presentation

The COMEX group is concerned with experimental kinetics and dynamics of gas phase reactions. Most of the processes under investigation are important in diverse environments such as the atmosphere of the earth, the planets and the interstellar medium.

Research activity

The COMEX group investigates the reactions of atoms such as C, O, N, Cl …or radical species such as CH, OH, C2 etc.. with hydrocarbon molecules/radicals and other small molecules/radicals of importance to interstellar environments and planetary atmospheres. Our group uses a variety of experimental methods (pulsed, crossed molecular beam technique; fast flow tube; supersonic flow reactor) alongside theoretical investigations of these processes to determine product branching ratios and reaction rate coefficients to low temperatures. The group is also involved in the development of the KInetic Database for Astrochemistry.

Key Words

Astrochemistry, planetary atmospheres, interstellar medium.
Reaction dynamics, reactive collisions, gas phase kinetics, reactivity at low temperatures (50 K) and low collision energies (35 J/mol), product determinations.
Fast-flow and supersonic flow reactors, crossed molecular beams, laser + Doppler-Fizeau spectroscopies, resonance enhanced multiphoton ionisation + time-of-flight mass spectrometry, statistical calculations.

Group members

Bergeat Astrid,
Hickson Kevin,
Loison Jean-Christophe,
Morales Sébastien,
Naulin Christian (group leader).

Recent publications

Observation of Partial Wave Resonances in Low-Energy O2 – H2 Inelastic Collisions.
Simon Chefdeville, Yulia Kalugina, Sebastiaan Y. T. van de Meerakker, Christian Naulin, François Lique, Michel Costes, Science 341 (2013) 1094.

Revealing Atom - Radical Reactivity at Low Temperature Through the N + OH Reaction.
Julien Daranlot, Mohamed Jorfi, Changjian Xie, Astrid Bergeat, Michel Costes, Philippe Caubet, Daiqian Xie, Hua Guo, Pascal Honvault, Kevin Hickson, Science, 334, (2011) 1538.

Quantum dynamical resonances in low-energy CO(j = 0) + He inelastic collisions.
Astrid Bergeat, Jolijn Onvlee, Christian Naulin, Ad van der Avoird and Michel Costes, Nature Chemistry. 7 (2015) 349.

Elemental nitrogen partitioning in dense interstellar clouds.
Julien Daranlot, Ugo Hincelin, Astrid Bergeat, Michel Costes, Jean-Christophe Loison, Valentine Wakelam, Kevin M. Hickson, PNAS, 109, (2012) 10233.

Dynamics of the S(1D2)+HD(j=0) Reaction at Collision Energies Approaching the Cold Regime: A Stringent Test for Theory .
Manuel Lara, Simon Chefdeville, Kevin M. Hickson, Astrid Bergeat, Christian Naulin, Jean-Michel Launay and Michel Costes, Phys. Rev. Letters 109 (2012) 133201.

The gas-phase chemistry of carbon chains in dark cloud chemical models.
Jean-Christophe Loison, Valentine Wakelam, Kevin Hickson, Astrid Bergeat, Raphael Mereau, MNRAS, 437 (2014), 930.

Photolysis of methane revisited at 121.6 nm and at 118.2 nm: quantumyields of the primary products, measured by mass spectrometry
Loison, JC ; Halvick, P ; Gans, B ; Boye-Peronne, S ; Broquier, M ; Delsaut, M ; Douin, S ; Fellows, CE ; Lucchese, RR ; Gauyacq, D ; Physical Chemistry Chemical Physics , 13 (2011) 8140.

Address & contact number

Adress : ISM, Building A12, 4th floor EAST
Email :
Phone : +33 5 40 00 24 67

Reaction cross-sections /crossed molecular beams

The aim is to get microscopic information SUCH as integral and differential cross sections on bimolecular reactive collisions in the very low collision energy regime prevailing in the interstellar medium. Experiments are performed with a crossed molecular beam apparatus which associates pulsed (...)

Low temperature chemical kinetics: The CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme) / Laval nozzle method.

The objective is to obtain information on the reactivity of species present in astronomical environments (molecular clouds, planetary atmospheres...) or of reactions relevant to the Earth’s atmosphere. Reactions between neutral species which do not pass over an energy barrier are often seen to (...)

Product determination by mass spectrometry in a flow-reactor

The main goal of this research activity is the identification of the product channels of the reactions of OH radicals and atomic chlorine with various volatile organic compounds with an interest in atmospheric chemistry. These studies are performed in collaboration with Eric Villenave from the (...)

Kinetics Database for Astrochemistry

Current interstellar chemical models need to be greatly improved to interpret new data arising from two powerful observational instruments: the Herschel Space Observatory (HSO) and the Atacama Large Millimeter Array (ALMA). In collaboration with Valentine Wakelam from the Laboratoire (...)


La synthèse organique bordelaise à l’honneur !
18 December 2017

Stéphane Quideau est le lauréat 2017 du prix de la Division de (...)

Publication d’un article dans Nature Chemistry - Groupe COMEX
31 May

Des chercheurs du groupe COMEX ont mis en évidence le comportement (...)