Light-induced multiple electronic-state coupling of O-2(+) in intense laser fields

The dissociation processes, O-2(+)-->O++O, in intense laser fields (100 fs, similar to 3x10(14) W/cm(2)) are studied at the laser wavelength of 795 an d 398 nm on the basis of the momentum imaging maps of the O+ fragment ions. The covariance map measurements are performed with high momentum resolutio n to assign securely the dissociation pathways. From the anisotropic moment um distribution of O+ with respect to the laser polarization direction, the electronic states of O-2(+) are found to be coupled exclusively through pa rallel transitions in the course of the dissociation process. The released kinetic energy of O+ for both 795 and 398 nm are interpreted consistently b y a sequential coupling model of light-dressed potential curves of O-2(+) i n the quartet Pi state manifold. (C) 2001 American Institute of Physics.