Natural lifetimes of excited states of neutral nitrogen determined by time-resolved laser spectroscopy

Radiative lifetimes were determined for three quartet states of neutral nitrogen, and sequences of Rydberg states were studied using depletion spectroscopy. Free nitrogen atoms were generated by photodissociation of ${\mathrm{N}}_2$O using frequency-tripled dye-laser radiation that was two-photon resonant with the 2${\mathit{p}}^2$3p ${}_{}{}^4{}_{}{}^{}$S or ${}_{}{}^4{}_{}{}^{}$D states. Further quartet states were reached by a subsequent single-photon absorption. We obtain τ(2${\mathit{p}}^2$3p ${}_{}{}^4{}_{}{}^{}$ ${\mathit{D}}_{7/2}$)=44(2) ns, τ(2${\mathit{p}}^2$3p ${}_{}{}^4{}_{}{}^{}$ ${\mathit{S}}_{3/2}$)=26.0(1.5) ns, and τ(2${\mathit{p}}^2$6${\mathit{s}}^4$ ${\mathit{P}}_{5/2}$)=41(7) ns.