NONLINEAR DYNAMICS OF LARGE-AMPLITUDE MOLECULAR-EXCITATION BY SHAPED OPTICAL PULSE SEQUENCES

The effects of nonlinear dynamical phenomena on strategies for creating large amplitude excitations in molecular systems are studied. A simple area-preserving mapping modeling a Morse oscillator coupled to a second intramolecular degree of freedom is considered. The optical field is approximated by a finite sequence of impulsive interactions with arbitrary amplitudes and time increments. the goal of exciting the system to 75% of its dissociation energy is established. For the uncoupled Morse oscillator, an analytic solution for the optimal spacing between pulses of minimal equal intensity is given. When intramolecular coupling is present, the existence of a nonlinear resonance zone is shown to strongly interfere with the efficacy of this strategy. Dramatic improvements in efficiency can be obtained by employing pulse sequences that explicitly take into account the presence of strong perturbations of the zeroth order phase portrait.