Nonlocal thermodynamic equilibrium effects of vibrationally excited NO

Abstract

The vibrational distribution of NO(X 2π) from the reaction O(3P)+NO2(X 2A1)→NO(X 2π,v″)+O2 was studied at room temperature in a fast-flow system. Oxygen atoms were produced via the microwave-discharge dissociation of molecular oxygen with argon as the carrier gas. The reaction time between the NO2 molecules and the oxygen atoms was kept at ∼3 ms to minimize vibrational energy quenching. NO(X) radicals were detected via laser-induced fluorescence of the A 2Σ+←X 2π electronic transition. The relative vibrational population ratio of NO in the ground electronic state was determined to be 87.4±2.6% and 12.6±2.7% in the v″=0 and v″=1 levels, respectively. No higher vibrational states were observed. The NO vibrational population ratio measured in this study correlates well with the earlier observation of high vibrational excitation in O2.