Measurement of the lifetime of the metastablea’’Σg+1state ofN2

We have measured the lifetime of the a’ ’ ${}_{}{}^1{}_{}{}^{}\mathrm{\Sigma }_{\mathit{g}}^{+}{}_{}{}^{}$(v=0) level of ${\mathrm{N}}_2$ by monitoring through laser-induced vacuum ultraviolet fluorescence its population as a function of time after pulsed-electron excitation. The lifetime was measured for several rotational levels and found to be independent of the rotational level. The average lifetime is 3.49(10) μs. This lifetime suggests that predissociation, not radiation, is the main decay mode for this metastable level.