Knowledge Bank

Radiative lifetimes of electronically-excited $NO2$ which are of the same order of magnitude (0.5 - 3.7 $\mu$sec) as those predicted by the integrated absorption coefficient have been observed. Excitation is provided by a narrow-band (0.15 - 0.3\AA) tunable organic dye laser with output between 4544 and 4550\AA, a region previously identified by Douglas and $Huber1$ as containing some unperturbed lines which connect the ground state with a $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}B1$, Born-Oppenheimer excited state. These observations provide conclusive evidence for the severe perturbation of most of the levels of this state.