Coherent Control of Unimolecular Reaction Dynamics Based on a Local Optimization Scheme

Abstract

This chapter reviews recent progress in the theoretical study of coherent control of reaction dynamics developed in our laboratory. The coherent control is based on optimization theory of a linear time-invariant complex system. Since the reaction dynamics of interest are not a linear time-invariant system, the time-dependent Schrodinger equation describing the time evolution of the system from the initial time to the final state is divided into short time stages. The optimization procedure is carried out in each short time stage in which the system can be approximated to a linear time-invariant system. Such an optimization carried out by a succession of short time stages leads to a local optimization scheme. The optimized laser pulse shape in every short time stage is expressed by a feedback form. The local optimization procedure is valid not only for weak laser fields but also for strong fields. The coherent control theory is applied to three types of unimolecular reaction dynamics: dissociation of hydrogen fluoride, isomerization of hydrogen cyanide, and a pump — dump pulse control of a reaction via an upper electronic excited state. The results of these applications show that the local optimization procedure is an effective tool for guiding the pulse shaping of unimolecular reactions.