I. Distorted-wave approximation in quantum transition state theory with application to collision -recombination processes. II. Golden rule flux -flux expressions for collision-mediated photo -absorption, and III. Dipole orientation of linear molecules us

Part I. Distorted-wave approximation is incorporated into the flux-flux autocorrelation function to calculate the cumulative reaction probabilities N(E) for collision-recombination reactions. The motion of the buffer gas is decoupled from the motion of the reacting molecules without using the strong collision approximation.;Part II. The cumulative reaction probability N(E) for two-surface scattering system coupled radiatively. The cases of bound-bound, bound-continuous, and continuous-continuous system are treated individually. In the case of continuous-continuous system, the exact and approximated formulas are developed to compute N( E) as a flux-flux autocorrelation function.;Part III. Using a static field to orient simple linear molecules requires very large field strengths. This part of work suggests combining a nonresonant optical field with a moderate static field to achieve molecular orientation. Calculations for HCN show that, due to the asymmetric feature of the combined field, aligning simple linear molecules along a moderate-strength static field is feasible.