Gas phase molecular complexes can be bound by weak intermolecular interactions to form dimers or larger clusters. They are considered to be the precursors of the condensed phase. Many studies in the field of cluster formation are motivated by the need to understand the formation of aerosols in the Earth’s atmosphere, as they are involved in the greenhouse effect. Aerosols are also observed in the atmospheres of other planets or their moons (e.g. Titan), in the interstellar medium or in combustion environments.
To understand the formation of clusters in such a diversity of environments in terms of temperatures or pressures, it is of fundamental interest to study the mechanisms involved in their growth. Our contribution in this field is to determine the rate of formation of various weakly bound complexes formed at very low temperatures. We have studied the kinetics (and thermodynamics) of formation of HO-O2 , as well as benzene  and pyrene  dimers. We are currently studying the kinetics of formation of water dimers and small hydrocarbon clusters. Spectroscopic studies of molecular complexes are also performed in our group.
-  S.D. Le Picard, M. Tizniti, A. Canosa, I.R. Sims, I.W.M. Smith, Science, 328, 1258-1262 (2010)
-  S. Hamon, S.D. Le Picard, A. Canosa, B.R. Rowe, I.W.M. Smith, J. Chem. Phys., 112, 4506 (2000)
-  H. Sabbah, L. Biennier, S. J. Klippenstein, I. R. Sims, and B. R. Rowe, J. Phys. Chem. Lett. 1, 2962-2967 (2010)