Group of theoretical chemistry, Laboratoire de Spectrométrie Ionique et Moléculaire- Lyons
Dr. Marie-Christine Bacchus
The activity of the group is mainly devoted towards two thematics:
Charge transfer in collisional processes: we have developed a complete treatment including ab-initio molecular calculations followed by semi-classical or quantal dynamical calculations which has shown its efficiency in a large number of cases. This field is now oriented to charge transfer in ion/biomolecule, and as a first example we treat the Cq+ + uracyl collisional system in relation with the work of the group in Gröningen.
Non-adiabatic effects in photodissociation processes: wave-packet time-dependent collisional approaches have been developed in the framework of the reduced dimensionality approximation in order to treat such problems involving a great number of degrees of freedom. An interesting situation appears in the analysis of competitive dissociation after photonic excitation in time-resolved femtosecond pomp-probe spectroscopy experiments. Important non-adiabatic effects around the avoided crossings have been shown in particular to drive the competitive C-Cl and C-Br bond breaking in the bromoacetyl chloride photodissociation process. Conical intersection behaviour is now investigated in the photodissociation of the vinoxy radical CH2CHO in ketene.
In the action of radiation or ions on biomolecular systems, the mechanism could generally be separated into two steps, a first step, very rapid and localised, which involves elementary processes as charge transfer, followed by the relaxation of the molecule. Information on initial mechanisms intervening in such reactions, or life-time of excited species could then be provided by approaches we have developed previously for rapid processes as photodissociation or charge transfer reactions.
COST P9 Workings group(s) of interest: WG4