Knowledge Bank

Results from ab initio calculations on the low-lying excited states of $NO2$ and $O_{3} $are presented. We find eight excited electronic states for $NO2$ with calculated vertical excitation energies less than 7 eV while for $O3$ there are nine excited states below 6 eV. For each molecule there exists one excited state $(2B1$ for $NO2$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}A1$ for $O3)$ with the geometry of a three-membered ring.