Principle of CICR experiments
1. Clusters generated in a supersonic expansion. Mean size : several thousands of monomers. Temperature : 30K for argon clusters. <1K for helium
2. Pick-up of the reactants : the cluster beam crosses a collision cell or a secondary beam containing the species to be picked-up.
3. After the pick-up the reactant are free to migrate at the surface (or inside) the cluster. They react when possible or they associate as non reactive complexes when energy barriers are present.
4. Laser excitation to turn on the reaction
5. Spectroscopic analysis.
The group Reaction Dynamics at Laboratoire Francis Perrin has developed since 1997 an original research direction, named « Cluster Isolated Chemical Reaction ». The aim is to study a small system (a single reactant, a pair of reactants or controlled number of reactants) interacting with a large system that has numerous degrees of freedom (a cluster) [1,2]. With argon clusters, the idea is to study how the dynamics of the small cluster is affected by the presence of the large cluster. This addresses fundamental concepts in heterogenous chemistry. With helium clusters, that are superfluid as a first approximation, the dynamics and the spectroscopy of the essentially unperturbed small system can be explored. In that case, the helium cluster serves as a tool to create extremely cold reactive systems (this research program is currently under development).
Among recent works :
 Mestdagh, J. M. ; Gaveau, M. A. ; Gee, C. ; Sublemontier, O. ; Visticot, J. P. Int. Rev. Phys. Chem. 1997, 16, 215.
 Gaveau, M. A. ; Gée, C. ; Mestdagh, J. M. ; Visticot, J. P. Comments At. Mol. Phys. 1999, 34, 241.