SEARCHING FOR THE N-2-A'5-SIGMA-STATE

Using a calibrated laser induced fluorescence method employing the Herman infrared band system in the nitrogen atom afterglow and in a new short-lived nitrogen afterglow it is demonstrated that less than 4×107 cm-3 N2(A′ 5Σ) are present. It is concluded that if the nitrogen atoms statistically expected to recombine into the 5Σ state do so then the nitrogen quenching rate constant of the 5Σ state must be greater than 1×10_11 cm3 s_1. Also, the 5Σ state is not the precursor to the short lived N2 afterglow recently described by Piper [J. Chem. Phys. 88, 6911, 232 (1988)]. © 1990 American Institute of Physics.