The 2491 Å band system of NO2. Rotational structure and evidence for predissociation in the zero-point level

Abstract

A detailed rotational analysis of the (0, 0) band of the [Formula: see text] electronic transition of NO2, at 2491 Å, has been carried out. Although the lines are slightly broadened as a result of predissociation, it has been possible to determine the five quartic centrifugal distortion constants and the spin–rotation coupling constant εaa for the upper state. The centrifugal distortion constants allow the position of the unseen vibrational level ν3′ to be estimated: the results offer no support to the suggestion of Coon, Cesani, and Huberman that there is a double minimum potential function in the antisymmetric stretching coordinate of the 2B2 state. The geometric structure of the zero-point level of the 2B2 state is r(N—O) = 1.3142 Å, [Formula: see text], and its lifetime (as calculated from the linewidths) is 42 ± 5 ps.