Seminars Archive

Rotationally inelastic scattering of the OH radical

Abstract
The collision experiments are a powerful tool to investigate molecular interactions. Relevant to the interstellar processes, atmospheric chemistry and combustion, the hydroxyl radical is an interesting collision partner. The outcome of a collision is determined by parameters like collision energy, impact parameter, relative orientation and internal energy. Many of these parameters are well defined in our cross beam experiments. The techniques employed for the production, state selection and orientation of the hydroxyl radical molecules are presented, together with the state-to-state cross-sections and steric asymmetries for the OH scattering by rare gases and halogen hydrides. The interaction of the OH molecule with a rare gas atom constitutes a first step in complexity and has be approached theoretically into more details, while the diatom-diatom interactions are far from being well understood. The high reactivity of the OH with hydrogen halides and the ability of the halogen products to catalyze the ozone degradation give to these systems study a special importance. Comparisons among the results obtained for scattering systems like OH-He [1], Ar [2] or Xe and OH-HCl [3], HBr [4] and HI [5] point to features of the rich landscape of the Potential Energy Surfaces that are probed. Differences in mass, size, electric moments and polarizability of the OH collision partner are reflected in the measured quantities. [1] K. Schreel, J. Schleipen, A. Eppink and J.J. ter Meulen, J. Chem. Phys. 99, 8713 (1993) [2] M.C. van Beek, J.J. ter Meulen and M.H. Alexander, J. Chem. Phys. 113, 628 ( 2000) [3] R.Cireasa, M.C.van Beek, A.Moise and J.J. ter Meulen, J. Chem. Phys. 122, 074319 (2005); 123, 064310 (2005) [4] A.Moise, R. Cireasa, D.H.Parker and J.J. ter Meulen, J. Chem. Phys. 125, 204315 (2006) [5] A.Moise, D.H.Parker and J.J. ter Meulen, J. Chem. Phys., submitted