Observation of Direct Dissociative Ionization in Molecular Hydrogen

Direct dissociative ionization is the simplest three-body breakup process in H₂. We describe the experimental verification of direct dissociative ionization to the repulsive A²Σ⁺_u state by resolving the kinetic energy and angular distributions of the formed protons. A \(2+1\) resonant enhanced multiphoton ionization process via the isotropic E,F ¹Σ⁺_g\(v = 6,J = 0\) level is employed. The structure in the kinetic energy spectrum is well described by a projection of the vibrational wave function of the E,F ¹Σ⁺_g\(v = 6,J = 0\) state onto the repulsive ionic state. The electronic character of the ionization continuum is revealed by the proton angular distribution.