HIGH-RESOLUTION FOURIER-TRANSFORM SPECTROSCOPY OF THE MEINEL SYSTEM OF OH

The infrared spectrum of the hydroxyl radical OH, between 1850 and 9000 cm-1, has been measured with a Fourier transform spectrometer. The source, a hydrogen-ozone diffusion flame, was designed to study the excitation of rotation-vibration levels of the OH Meinel bands under conditions similar to those in the upper atmosphere which produce the nighttime OH airglow emission. Twenty-three bands were observed: nine bands in the DELTAupsilon = 1 sequence, nine bands in the DELTAupsilon = 2 sequence, and five bands in the DELTAupsilon = 3 sequence. A global nonlinear least-squares fit of 1696 lines yielded molecular parameters with a standard deviation of 0.003 cm-1. Term values are computed, and transition frequencies in the DELTAupsilon = 3, 4, 5, 6 sequences in the near-infrared are predicted.