PRODUCT STATE CONTROL THROUGH INTERFERING EXCITATION ROUTES

We have demonstrated control over the branching ratio for photoionizat ion into two different continuum channels of atomic barium using an in terference between two distinct photoexcitation routes. Each pathway f or photoionization is a two-photon process, and is resonantly enhanced by an intermediate state. We have found the unexpected situation of d estructive interference when both lasers are resonant with their respe ctive transitions. The magnitude of the interference, as well as the e xceptionally broad wavelength range over which the interference persis ts, is also quite surprising.