On using shaped light pulses to control the selectivity of product formation in a chemical reaction: An application to a multiple level system

A previously reported method for shaping electromagnetic field pulses to achieve chemical selectivity is extended and applied to a simple multiple level model system. The pulse shaping approach is based on optimal control theory, where both the time-dependent Schrödinger equation and the constant pulse energy are used as constraints on the variational scheme. A conjugate gradient direction method is used to direct the convergence of the iterative process used to calculate the optimum pulse shape. The method is applied to a five-level system interacting with an optical (laser) field. Results demonstrating selectivity and stability are compared to those of other recent related investigations.