Vibronic Level Density of Excited NO₂‐States and its Statistical Analysis

Abstract

Abstract Measurements of vibronic term values in excited electronic states of NO 2 have been performed with cw dye lasers over the whole spectral range from 12117 cm −1 to 24563 cm −1 . The low rotational temperatures, achieved by adiabatic cooling of NO 2 seeded in a supersonic argon beam, allow the separation of closely lying bands as well as a distinction between transitions to the 2 B 1 state and the vibronically coupled 2 B 2 – 2 A 1 states. The statistical analysis of the distribution P ( S ), where S is the energy separation between adjacent vibronic levels and of the intensity distribution of all measured bands, suggests that a short range correlation exists between the excited levels. Whether also a long range correlation exists is still under investigation. A definite answer requires an unambiguous determination of all bands even with low intensities and a safe assignment of all hot bands. These points are discussed in detail.