Lifetime measurements on the

Excited state lifetimes of c4′1Σ+u, v=0–2 states of molecular nitrogen have been determined in a laboratory investigation using a picosecond XUV laser in a pump–probe configuration. For c4′1Σ+u, v=0 the lifetime is τ=740±50 ps, for the lowest rotational states. For higher rotational states a gradual shift towards τ=495 ps is found in agreement with previous findings that these states are subject to predissociation. For c4′1Σ+u, v=1 no J-dependence is found and values for two isotopomers are reported: τ=330 ps for 14N2 and τ=240 ps for 14N15N. For c4′1Σ+u, v=2 a lifetime for the lowest rotational states (J=0–3) was derived: τ=675±50 ps; for J=11 a lifetime of τ⩽120 ps is deduced. All values for the lifetimes including the J-dependences are explained in a model based on Rydberg-valence interaction.