The dynamics of a chemical reaction in the region of its transition state is the principal information that must be collected for a detailed description of the reaction mechanism. Essentially two experimental routes lead to this information:
in the time domain as done in the organic femtochemistry activity of the reaction dynamics group at Laboratoire Francis Perrin,
spectroscopically as done in other activities of the group (CICR and EDELWEISS)
In both directions, the chemical reaction under study is turned on by laser excitation. The latter occurs with no geometrical change of the reactive system but the gradients along the excited potential energy surface induce the necessary momentum to the system to push it to reaction. The spectroscopical information carries essentially on the Franck Condon region of the photoexcitation and on the final state of the reaction products. In contrast, the temporal information allows to explore the system in its way through geometrical conformations and electronic configurations that are very different than those accessible in the Franck Condon region. Of course these two information are complementary, hence justifying that our group conducts experiments of both types.