J. TANG AND T. OKA, Department of Chemistry, The University of Chicago, Chicago, IL 60637.
Infrared spectrum of H3O+ has been observed by a difference frequency laser spectrometer with positive column discharges of H2/O2 gas mixtures, which gave a spectrum remarkably simpler than the previous one with H2/O2/He discharges. After extending the previous assignment of the 3 fundamental bands to higher J, K transitions, vibration-rotation structures due to the 1+ \gets 0- and 1-\gets 0+ bands of H3O+ were identified with the band origins of 3389.66 cm-1 and 3491.17 cm-1, respectively, in the region of the strong 3\pm\gets 0\pm bands. Molecular constants for the 1\pm\gets 0\mp bands were obtained by the least-squares fittings for the observed frequencies. Coriolis interactions between the 1 and 3 vibrations have been considered to explain some large deviations of the observed transitions from the calculated frequencies in the 1 and 3 bands.