Photodissociation of CO(-3): Product Kinetic Energy Measurements as a Probe ofExcited State Potential Surfaces and Dissociation Dynamics

摘要

The photodissociation process CO3- + hv = phi- + CO2 has been investigated atphoton energies of 2.41, 2.50, 2.54, 2.60 and 2.71 eV. Experiments were conducted by crossing a mass-selected, 8 keV ion beam with a linearly polarized laser beam, and measuring the kinetic energy distributions of the charged photodissociation products. By varying the angle between the ion beam and laser polarization, angular distributions were obtained at photon energies of 2.41 and 2.54 eV. The photon energy dependence of the average photofragment kinetic energies shows conclusively that photodissociation at these photon energies does not proceed by a direct dissociation process on a repulsive potential surface, or by a statistical vibrational predissociation process on a bound surface. The photofragment angular distributions are isotropic, providing further evidence that precludes direct photodissociation on a repulsive potential surface. Ab initio calculations were performed using the GAUSSIAN86 programs. These