Wide-range absolutephotodetachment photodetachment spectrum of NO2−

Dye-laser photodetachment of the electronic and vibrational ground state of N$\mathrm{O}_2^{}{}_{}{}^{-}$ is accomplished in a mass-identified drifted tube. Photodetached electrons are detected. The absolute-magnitude photodetachment spectrum is determined in the visible range of 5400 to 4350 Å and the ultraviolet range between 3550 and 2600 Å. The size of the cross section varies by more than 3 orders of magnitude when the size of the lowest vibrational transition is compared with that of the total cross section at ultraviolet energies. The electron affinity of N$\mathrm{O}_2^{}{}_{}{}^{-}$ is determined to be $E_A\left({\mathrm{NO}}_2^{-}\right)=2.275\mathrm{}\pm 0.025$ eV. A Franck-Condon factor analysis of the absolute-magnitude spectrum yields, for the first time, structural constants of N$\mathrm{O}_2^{}{}_{}{}^{-}$ in the free gas phase. They are $r=1.15\mathrm{}\pm 0.02$ Å and $\theta ={119.5}^{\circ }\pm {1.0}^{\circ }$. The solar detachment rate of N$\mathrm{O}_2^{}{}_{}{}^{-}$ is 0.042±0.010 ${\sec }^{-1\mathrm{}}$. A peroxy isomer of N$\mathrm{O}_2^{}{}_{}{}^{-}$ is not detected.