OBSERVATION OF HIGH-N HYDROXYL PURE ROTATION LINES IN ATMOSPHERIC EMISSION-SPECTRA BY THE CIRRIS 1A SPACE-SHUTTLE EXPERIMENT

Pure rotation line emissions from highly rotationally excited OH have been observed between 80 and 110 km tangent height under both nighttim e and daytime quiescent conditions. Data were obtained using the cryog enic CIRRIS 1A interferometer, operated on the Space Shuttle. Transiti ons from OH(v = 0-2, N' less-than-or-equal-to 33) were identified betw een 400 and 1000 cm-1, corresponding to states with energies as high a s 23000 cm-1. These are the first definitive observations of OH pure r otation transitions in the airglow, and by far the highest N levels ob served in any type of OH airglow emission spectrum. The present observ ations of highly excited rotational states of OH parallel those made d uring recent field studies of NO and laboratory studies of OH, NO, and CO.