Photoionization and photodissociation dynamics of H2 after (3+1) REMPI via the B state

We present a study of the molecular photoionization and photodissociation processes in molecular hydrogen occurring after one-photon absorption from various rovibrational levels (v = 3-22, J = 0-3) of the B 1(1sg)(2pu) state using resonance-enhanced multiphoton ionization in combination with high-resolution photoelectron spectroscopy (REMPI-PES). For one-photon absorption from the v = 3-8 levels, molecular photoionization competes with photodissociation into a ground-state atom and an atom in an n = 2 excited state. A detailed comparison of the photoelectron spectra obtained via different rotational branches and vibrational levels strongly indicates that singly excited bound 1 and 1g Rydberg states at the four-photon level exert a significant influence on the final state distributions of H. In contrast, one-photon absorption from the v = 9 and higher levels leads almost exclusively to dissociation into a ground-state atom and an excited-state atom with n > 2. Excited atomic fragments are ionized in a one-photon absorption step, and excited-atom distributions over the energetically allowed values of the principal quantum number n are obtained. Simulations of these distributions suggest that excitation of dissociative continua of bound 1(1sg)(nsg), 1(1sg)(ndg), and 1g(1sg)(ndg) Rydberg states may dominate over excitation of dissociative doubly excited 1(2pu)(npu) and 1g(2pu)(npu) states when considering the dissociation dynamics after one-photon absorption from the v9 levels of the B-state.