Laser intensity induced nonradiative processes in molecules

Abstract

The effects of the coupling strength (i.e., the Rabí frequency) of a coherent radiation mode interacting with a multilevel molecule are considered. A doorway-state basis is used in which the radiative doorway state, carrying all of the radiative interaction strength from the ground (initial) state, is coupled by intramolecular (nonradiative) interaction to other excited states. The resulting coupling scheme involves an effective Hamiltonian formulation in an extended rotating basis. Quantitative results from the theory are obtained by computer simulation. It is shown how variation of the laser coupling strength can modify the dynamics of nonradiative transitions, thereby producing (1) decoupling of radiationless decay, (2) enhancement of radiationless decay, (3) selectivity of photophysical and photochemical processes, or (4) laser-induced isolation of states, depending on the conditions of the system. The case of two states coupled through a common manifold of states and the conditions for biexponential decay are also considered.