Wavepacket dynamics and predissociation of the D 1Πu state of Rb2

We present the first experimental investigation of the real-time dynamics of predissociation in a diatomic molecule involving more than two electronic states – the predissociation of the D 1Πu state of Rb2. Our results show that the state is strongly predissociated, τ≈5 ps, above a sharp energy threshold. We propose that mainly the (1) 3Δu state causes the fast predissociation and that the fine-structure components of the products are mixed by coupling among molecular states at large internuclear distances. Furthermore, an outward–inward asymmetry of the wavepacket signal is attributed to autoionisation of the wavepacket evolving in the probe (Rydberg) state.