The Combustion and Reactive Systems Laboratory (Laboratoire de Combustion et Systèmes Réactifs - LCSR) in Orléans belongs to CNRS. The main research areas are combustion chemistry and physics and atmospheric reactivity. The "atmospheric reactivity" group  includes four permanent scientist at CNRS, Drs Véronique Daele, Georges Le Bras, Wahid Mellouki and Yuri Bedjanian and temporary co-workers. The group investigates mainly reactions of interest for the upper troposphere-lower stratosphere, chemical mechanisms of VOC oxidation and heterogeneous reactions on soot and related substrates.  

The facilities, currently used to investigate homogeneous or heterogeneous kinetics and mechanisms of atmospheric chemical systems, are flow reactors coupled to mass spectrometers, pulsed laser photolysis coupled to laser induced fluorescence analysis, UV-visible absorption cell with diode array detection, simulation chambers.

Turbulent Flow Reactor coupled to Chemical Ionisation Mass Spectrometer (TFR-CIMS)
A TFR-CIMS equipment developed at LCSR is used to study kinetics and mechanisms of reactions at pressures from a few Torr to 700 Torr and at atmospheric temperatures down to 200 K (eg Kukui et al. J. Phys. Chem. A (2003) 107, 5732, Butkovskaya et al J. Phys. Chem. A (2004) 108, 7021). An UV-Vis absorption cell located upstream of the TFR allows precise measurements of the molecular reactant concentrations. This equipment is particularly suitable for mechanistic sudies at the low temperatures of the upper troposphere.

Pulsed Laser Photolysis-Laser Induced Fluoescence (PLP-LIF)
A PLP-LIF equipment is used to measure reaction rate constants over a large range of temperatures and pressures (Mellouki et al. J. Chim. Phys. (1994) 91, 473). OH reaction with a large variety of compounds can be investigated and the obtained data are used to derive atmospheric lifetimes of the compounds and structure-reactivity relationships. A UV-vis absorption cell with diode array detection is also available for measuring absorption cross sections of compounds in order to verify their neligible photodissociation in PLP-LIF experiments. Cross sections measurements are also carried out for potential photolabile compounds in the atmosphere.

Coated Flow Reactor coupled to Electron Impact Ionisation Mass Spectrometer
This equipment used so far at LCSR to investigate kinetics and primary mechanism of gas phase radical-molecule and radical-radical reactions has been recently adapted for studies of heterogeneous reactions of gaseous atmospheric oxidants with soot (Lelièvre, Bejanian et al. PCCP (2004) 6, 1181). Fresh soot produced under controlled conditions at LCSR is used as substrate in the flow reactor. The uptake coefficients of the gaseous oxidants and the interaction mechanisms with soot are determined by monitoring the gaseous phase. This experimental set up is going to be equipped with analytical instruments to investigate the condensed phase.

Simulation chambers
Teflon bags of 200 L irradiated by UV-visible lamps are available to study the chemical mechanisms of VOC oxidation in air at atmospheric pressure in the presence of different concentrations of NOx. The analysis of the species at different reaction times are carried out by FTIR, GC-MS and GC-FID after sampling.

A chamber of 8 m3, irradiated by lamps, is also available. It is used for mechanistic studies of VOC oxidation including secondary aerosol formation. The chamber is equipped with the same analytical techniques as those coupled to the teflon bags. A FTIR in situ analytical system is under installation. A SPMS instrument is also available for measurements of size particle distribution. The techniques to be developed for the analysis of the condensed phase in the flow reactor studies will also be available to measure the chemical composition of secondary organic aerosols (SOA) formed in the chamber. Besides, a flow tube at atmospheric pressure has also been set up recently to study the SOA formation in the ozonolysis of unsaturated hydrocarbons.