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Accueil > Séminaires > 2014

Frustrated Dynamics at the Double Bond

Baptiste Joalland, Wayne State University (Detroit, USA)

Séminaire LCPQ

Salle de séminaire IRSAMC

The first part of my talk will concern the photodynamics of ethylene cation C2H4+, the simplest π radical cation, which is a prototypical system for vibronic couplings involving Jahn-Teller interactions. By combining electronic structure calculations with excited state trajectories, I will show how two competing families of nonadiabatic transitions can influence the subsequent dynamics on the ground state and promote specific dissociation pathways. This study provides a better understanding of the photochemical dynamics of highly electronically frustrated radicals with regards to the emergence of new femto/attosecond pump-probe laser techniques.

The second part will be dedicated to the dynamics of chlorine atom reactions with saturated and unsaturated hydrocarbons, which are important in atmospheric and combustion processes. The analysis of reactive scattering distributions measured in a crossed-beam imaging set-up will emphasize the typical distributions associated with direct and indirect mechanisms. I will demonstrate that at low collision energies, Cl reactions with alkenes are dominated by addition-elimination reactions for which the frustrated π adducts must undergo near-dissociation before eliminating HCl at the adjacent saturated sites. These results suggest that roaming radical dynamics, now widely recognized in unimolecular reactions, may play a central role in a broad class of bimolecular reactions as well.