Quantum theory of laser catalysis in one and three dimensions

A theory of the laser catalysis of the H + H₂ exchange reaction in the collinear configuration and in three dimensions is presented. The collinear H + H₂ system in a strong laser field is treated by a method composed of a converged coupled channels expansion for the non-radiative processes, coupled with an exact partitioning technique for the interaction with the radiation. The method enables computations to be performed for an arbitrary number of field-intensities with very little effort beyond that required for a single-intensity computation. By studying the optical reactive line-shapes as a function of the scattering energy, the signature of the scattering resonances on optically induced reaction is unravelled. It is shown that when the collision energy is tuned to a resonance, laser catalysis results in selective vibrational excitation of the product H₂ molecule. Implications of this effect for past and future experiments are discussed. A three-dimensional theory based on the same exact partitioning technique is then presented. In this case, the bound-free scattering amplitudes, which serve as input to the theory, are obtained by assuming separability in terms of a hindered-rotor vibrationally adiabatic basis. We use the theory to compute reactive differential and integral laser-catalysis cross-sections. We study the laser intensity dependence of the reactivity, the role played by isolated and overlapping power-broadened resonances and how the angle of the relative velocities of the reagents affects the reactivity.