A LoSurdo discharge was used to apply electric fields of up to 290 kV/cm to a mixture of cyanogen and hydrogen, and to ammonia, permitting the observation of Stark effects in the optical spectra of the CH and NH molecules, respectively. These experiments yielded the following values of the molecular electric dipole moment in the ground vibrational states: μ(CH, A2Δ) = 0.887 ± 0.045 D, and μ(NH, X3Σ) = 1.389 ± 0.075 D. A table of experimental and theoretical dipole moments of first-row hydrides is included.

Spectra due to the A Z Z + -X Z n transition of the hydroxyl radical in electric fields of over 300 000 V per cm have been obtained. The dipole moment of the AZE+ v = 0 state of O H has been determined to be (1.98 + 0.08) D. From the variation of the dipole moment with vibrational quantum number in the state, the transition probability for the pure vibrational transition v = 1 -+ v = 0 has been estimated to be A,, = 80s-'.Les spectres des transitions provenant de 1'Ctat A Z Z + -X Z n du radical hydroxyle dans des champs electriques depassant 300 000 V par cm ont ete obtenus. Pour le moment dipolaire de 1'6tat AZE+ v = 0 de OH, on a trouve (1.98 + 0.08) D. A partir de la variation du moment de dip6le avec le nornbre quantique vibrationnel dans 1'Ctat on a estime a 80 s-' la probabilite de la transition vibrationnelle v = l -+ v = O .

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