Predissociation of O2 in the B state

Dispersed LIF spectra of O2 in the Schumann–Runge band were measured with a modified tunable ArF laser in a flame. Spin-state selective predissociation of the B state was directly observed in fluorescence excitation spectra, revealing the relative coupling matrix elements of the triplet components to the manifold of repulsive states. Such data determines the symmetries of the important predissociating curves for each observed B-state vibrational level and shows that past interpretation of absorption linewidth data is in error. Due to the fast predissociation, quench-free emission spectra arising from laser prepared single rovibronic levels in the B state were observed even in an atmospheric flame. Fluorescence to X-state vibrational levels as high as v″=35 was observed and relative emission probabilities were derived.