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 Ap = 1 sequence, nine bands in the Ap = 2 sequence, and five bands in the Ap = 3 sequence. A global nonlinear least-squares fit of 1696 lines yielded molecular parameters with a standard deviation of0.003 cm-1. Term values are computed, and transition frequencies in the Ap = 3, 4, 5, 6 sequences in the near-infrared are predicted. Subject headings: laboratory spectra-molecular processes 351

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The most recent measurements leading to improved Li I energy levels appeared in the late 1950s. Since then, many highand ultrahigh-precision spectroscopy techniques have been used to measure the fine and hyperfine structures and isotope shifts of this atom. Most previous measurements were made on Li. Using highand low-current hollow cathode sources and Fourier-transform spectrometry, we have made measurements in both Li and Li including nine previously unmeasured infrared lines. Wave-number measurements were obtained on 34 lines from 1829 to 30 925 cm '. The strongest lines have been determined to~0.0010 crn '. We also measured 22 new isotope shifts, and added specific mass shifts for five levels. The resonance lines at 6707 A in both isotopes, emitted by low-current, commercial lithium hollow cathode sources, were measured tõ 0.0005 cm '. The energy levels have been recalculated using the new data. PACS number(s): 32.30.Jc

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