On the hypothesis of H2 as the carrier of the diffuse interstellar bands

In a laboratory experiment, employing an extreme ultraviolet/near-infrared double resonance technique, a recent hypothesis by Sorokin and Glownia on the carrier of the diffuse interstellar bands is tested. Quantum statesC1Πu+, v = 9, J = 1–3 of molecular hydrogen were populated by an extreme ultraviolet laser at 86 nm and used as absorber states for a second excitation step. In transitions to autoionizing doubly excited states of H2 many resonances of strongly varying widths were observed. The frequency positions and linewidths are in general not consistent with the observed diffuse interstellar bands in the range 766–788 nm, nor with the predictions of Sorokin and Glownia. However, two lines are found in the present study that do coincide with diffuse interstellar bands.