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

The rovibronic structures of gerade excited states of molecular hydrogen have been investigated between 117 000 cm−1 and the second dissociation limit with extreme ultraviolet visible double resonant excitation technique. Several levels have been unambiguously assigned to the v = 0 state of the 4s and 4d Rydberg members 4 s σ O 1 Σ g + , 4 d σ P 1 Σ g + , 4dπ R1Πg, and 4dδ S1Δg. The fluorescence lifetimes have been measured under collision free conditions for the first time, revealing that the lifetimes for the O 1 Σ g + ( v = 0 ) state, 172.8 and 193.7 ns for J = 0 and 1, respectively, are much longer than those for the 4d Rydberg states. The rotational dependence of the lifetimes for the EF + GK + H 1 Σ g + , I1Πg, and J1Δg states is discussed in terms of the nonadiabatic coupling among the upper gerade manifolds.