Fine-structure selectivity of neutral dissociation with excitation observed in O2

The absorption cross section of O2 and the O I (4So)3s 3So1→2p4 3PJ emission cross section were investigated near the threshold for neutral dissociation into the O I (4So)3s 3So1 state with a very narrow bandwidth (0.9 meV) of the exciting radiation. It was possible for the first time to resolve the fine-structure (FS) components of vibrational levels in the emission cross section and, in addition, to determine their relative intensities. A certain degree of selectivity in the population of FS components was observed. Furthermore, an absolute cross section for the dissociation into the fragments in the O I ground state or the metastable O I (4So)3s 5So2 state was estimated.