Resonant multiphoton ionization of H2 via the B 1Σ+u, v=7, J=2 and 4 levels with photoelectron energy analysis

We report measurements of photoelectron spectra of an electronically excited state of H2 (B 1Σ+u) in selected vibrational and rotational levels. The excited state was prepared by resonant three photon excitation of H2 X 1Σ+g, v=0, J=3 and subsequently was ionized by a single additional photon. Partially resolved rotational structure is observed in the photoelectron spectra and is discussed in terms of the selection rules for direct photoionization and the partial wave composition of the ejected photoelectrons. An additional peak is observed in the spectra, which is tentatively interpreted as arising from photoionization of H*(n=2) formed by photodissociation of H2 in the B 1Σ+u state.