15min:
HIGH-RESOLUTION SPECTRA OF MOLECULAR ANIONS: ANOMALOUS ASYMMETRY SPLITTING IN HNO-.

JOHN W. FARLEY, Department of Physics, University of Nevada, Las Vegas, NV 89154; AND DANIEL C. COWLES, Air Liquide Laboratories, 5-9-9, Tokodai, Tsukuba-shi, Ibaraki-Pref. 300-26, Japan.

Extensive measurements have been made of the infrared vibrational-rotational spectra of the H14NO- and H15NO- anions. The spectra were obtained using autodetachment spectroscopy, in which vibrational-rotational transitions are excited using a coaxial ion beam/infrared laser beam spectrometer. The vibrationally excited ions autodetach, producing a fast neutral which is detected. A total of 413 transitions have been measured in the fundamental N-H stretch. The measurements have sub-Doppler resolution, enabling the measurement of the asymmetry splitting. The asymmetry splitting, and rotational constants returned by a least-squares fit to the spectra, manifest an anomalously large dependence of the rotational constants upon isotopic substitution. The spectrum may be perturbed by a Coriolis interaction. Comparison is made with a theoretical calculation of the geometry of this species.