Interference effect in the two-photon ionization of nitric oxide

An experimental demonstration of the interference between two different resonant two-photon, two-color ionization processes from the A 2Σ+, v=1 state of nitric oxide will be presented. In brief, the two interfering ionization pathways correspond to 1 + 1' and 1' + 1 photon ionization via the E 2Σ+, v=1 and H 2Σ+, v=1 states, respectively. The two-color ionization process is distinguished from the competing one-color processes by using photoelectron energy analysis. This interference between the two two-color processes does not require a well-defined phase relationship between the ionizing lasers and should, in principle, allow control of the overall ionization process by small detunings of either or both of the two resonant ionization pathways. This interference effect is quite general; the potential of this scheme for the control of photoionization and photodissociation partial cross sections will be discussed