  We have developed a theory of three-pulse coherent control of photochemical
processes. It is based on adiabatic passage and quantum coherence and
interference attributed to the lower-lying dissociation continuum and excited
upper discrete states, which are otherwise not connected to the ground state by
one-photon transitions. Novel opportunities offered by the proposed scheme are
demonstrated through extensive numerical simulations with the aid of a model
relevant to typical experiments. The opportunities for manipulating the
distribution of the population among discrete and continuous states with any
necessary ratio by the end of the pulses are demonstrated.
