Resonant photon-catalyzed predissociation and autoionization: Fragment yield, rate constant, and rotational line strengths

General theory and analytic results are given for calculating the fragment yield and the rate constant of bound-to-continuum decompositions of atoms or molecules induced by a multiphoton effect called the resonant photon-as-catalyst effect (PCE). In this effect the rate constant of the reaction is increased due to the presence of the photons while the total number $N$ of photons in a given mode of the electromagnetic field is conserved. The decomposition processes include (1) photon-catalyzed (PC) predissociation from excited states of molecules in general, as well as from ground states in some cases of polyatomic molecules: $AB+N\hslash \omega \to A+B+N\hslash \omega$; and (2) PC autoionization of atoms or molecules: $A+N\hslash \omega \to A^{+}+e^{-}+N\hslash \omega$. Both pulsed and continuous-wave laser irradiation are studied. Optimization of the yield and the rate constant by the lifetimes of the molecular states are studied for the first time. Resonant enhancement [Lau, Phys. Rev. Lett. 43, 1009 (1979)] and coherent saturation [Lau, Phys. Rev. A 22, 614 (1980)] in this effect are further elaborated. Laser-stimulated decays and optical Stark shifts due to the continua and other nonresonant discrete states are included in the theory. The rotational line strengths for symmetric top molecules predissociated by resonant PCE using linear-polarized laser radiation are also given.