Photoabsorption cross sections of OH at 115–183 nm

The absorption spectrum for OH was obtained in the 115–183 nm region. The OH radicals were produced by a pulse discharge of trace H2O in few Torr of Ar. Absorption cross sections were obtained by calibration with absorption of the OH (A 2Σ+←X 2Π) transition. The features in the absorption spectrum are correlated with the excited states 1 2Σ−, D 2Σ−, 1 2Δ, B 2Σ+ and possibly others calculated by van Dishoeck, Langhoff, and Dalgarno. The measured cross sections are comparable with the calculated values.