On the control of resonant versus non-resonant electronic transitions in molecular photodissociation

An excitation scheme is regarded where a non-resonant three photon transition populates an excited electronic state leading to molecular dissociation. The absorption of an additional photon initiates a resonant transition to another state where different molecular fragments are built. The control of the relative yield of dissociation products in the two channels is achieved employing modulated laser pulses. The results derived from feedback control combined with a genetic algorithm and optimal control theory are compared, and it is shown that different physical mechanisms can lead to comparable branching ratios.