Laser fluorescence spectroscopy of 2B1 (K > 0) vibronic states of NO2

The low-pressure fluorescence spectrum of NO₂ excited by the narrow (0.5 GHz) HeCd laser transition at 441.6 nm is found to be quite complex, indicating a rather high density of transitions to final states at this energy. Seven fluorescing states exhibiting perpendicular selection rules have been assigned to ²B₁ (K > 0) vibronic states of NO₂. From the presence of final states with v₃″ = 2, a considerable amount of ²A₂ electronic state character is attributed to at least some of these states.