Spectroscopy of Rb2 dimers in solid He4

We present experimental and theoretical studies of the absorption, emission, and photodissociation spectra of Rb₂ molecules in solid helium. We have identified 11 absorption bands of Rb₂ . All laser-excited molecular states are quenched by the interaction with the He matrix. The quenching results in efficient population of a metastable (1)Πu3 state, which emits fluorescence at 1042nm . In order to explain the fluorescence at the forbidden transition and its time dependence we propose a new molecular exciplex Rb₂(Πu3)He₂ . We have also found evidence for the formation of diatomic bubble states following photodissociation of Rb₂ .