Laser Control of Chemical Reactions by Phase Space Structures

The question of what initial conditions or what kinds of laser fields can effectively carry a system to the desired products is one of the most intriguing subjects in chemistry. In this paper, a scheme for designing a laser field to guide a chemical reaction system into the product is presented on the basis of the phase space structure of the reaction with an illustrative simple example. The method exploits recent findings [Kawai et al., J. Chem. Phys. 2011, 134, 024317] that have revealed the existence of a rigorous reactivity boundary separating the reactive and non-reactive trajectories in the phase space (more precisely, the semi-classical phase space representation of the quantum system). Referring to the time propagation of the system, the method designs an electric field that actively shifts this reactivity boundary so that it catches more the system in the reactant and releases the system in the product. The success of this scheme for designing of the field gives a further support to the interpretation for the laser control of chemical reactions