Fluorescence lifetimes of the P1Σg+, R1Πg, and S1Δg states of D2

The extreme-ultraviolet-visible double resonance excitation technique has been used to investigate the rovibronic structure of gerade excited states of D2. The fluorescence lifetimes of the 4dσP1Σg+, 4dπR1Πg, and 4dδS1Δg(v = 0) states have been compared with those of H2. Nonadiabatic coupling among states in the upper gerade manifold accounts for the rotational dependence of the lifetimes of the EF+GK+H1Σg+ and I1Πg states. In addition to the gerade levels below the second dissociation limit (D (n = 1) + D (n = 2)), we have succeeded in measuring the lifetimes of the − component of the I1Πg(v = 5) and R1Πg(v = 1, 4-7) states which are located above the dissociation limit. No corresponding + component has been identified. The effect of predissociation on the radiative decay channel is discussed.