MICROWAVE-SPECTRUM OF THE MNO RADICAL IN THE X-6-SIGMA(+) STATE

The microwave spectrum of MnO in the (6) Sigma(+) ground electronic st ate was detected using a source-modulated submillimeter-wave spectrome ter. The MnO radical was efficiently generated by de sputtering of man ganese flakes placed inside a hollow cathode in the presence of an oxy gen and helium mixture. In total, 283 spectral lines were measured in the frequency region of 210-450 GHz for nine rotational transitions, e ach of which showed six. fine structure line groups consisting of seve ral hyperfine structure components due to the Mn-55 nucleus (l = 5/2). A least-squares analysis of the measured line frequencies resulted in the determination of rotational, fine. and hyperfine coupling constan ts including higher-order spin-orbit distortion terms for the spin-spi n, spin-rotation interactions and the Fermi contact interaction of the Mn nucleus, The hyperfine coupling constants were used to assess plau sible molecular orbital bonding models. (C) 1997 American Institute of Physics.