Stark effect enhanced dissociation of high Rydberg states in the D3 molecule

Various terms of non-adiabatic coupling in molecules show a pronounced isotope dependence. This dependence arises primarily from reduced mass effects and to a lesser extent from effects of nuclear spin. In order to examine isotope effects we have undertaken a comparative study of long-lived D3 and H3 molecules in high Rydberg states close to the ionization threshold. In our experiment the long-lived Rydberg states (τ> 500 ns) are induced to dissociate by a short electric field pulse experienced by the molecule when it transverses a miniature spatial region of high electric field (up to 20 kV/cm). We monitor in triple coincidence the three-body decay and compare the results of H3 and D3.