Theory of laser-induced chemi-ionization. I. Quantal formulation

The quantal theory of field-free associative ionization and Penning ionization, due to O'Malley, Bieniek, and others, is generalized to include the closely analogous laser-induced chemi-ionization processes A+B+hω→AB++e-, A+B++e-. The principal limitations of the theory are its reliance upon the two-state approximation and its neglect of Born-Oppenheimer terms. Formulas are derived for several scattering cross sections descriptive of the energy spectra and angular distributions of the reaction products. These cross sections vary with the direction of polarization of the laser radiation. The polarization dependences of the heavy-particle (A+B+) energy-angle double-differential cross section and of the associated heavy-particle (or photoelectron) energy distribution assume simple cosine-squared forms provided that there is a large number of contributing partial waves. Numerical calculations of these cross sections should be no more difficult to perform than for comparable field-free processes