RESUMO
The analysis of the nu6, nu7, nu8, and nu9 bands of H15N16O3 located at 646.9641, 578.4719, 743.6166, and 458.2917 cm-1, respectively, has been carried out in the 400-800 cm-1 region using high-resolution Fourier transform spectra recorded at Ottawa. Using the ground state energy levels calculated from the v = 0 rotational constants of H15N16O3 [A. P. Cox, M. C. Ellis, C. J. Attfield, and A. C. Ferris, J. Mol. Struct. 320, 91-106 (1994)], it was possible to assign the A-type nu6 and nu7 bands and the C-type nu8 and nu9 bands of H15N16O3 up to high J and Ka rotational quantum numbers. The v6 = 1, v7 = 1, v8 = 1, and v9 = 1 experimental energy levels were then introduced in a least-squares fit calculation and precise upper state Hamiltonian constants (band centers and rotational constants) were determined allowing one to reproduce the infrared data to within the experimental uncertainty. Copyright 1998 Academic Press.
RESUMO
The high-resolution FTIR spectrum of the nu8 + nu9 band of HNO3 around 1205 cm-1 has been measured and analyzed. The bright state was found to be strongly perturbed by its neighboring dark state nu6 + nu7 at the coincident levels. Taking account of the DeltaK = ±2 anharmonic resonance, a simultaneous fit of nu8 + nu9 and nu6 + nu7 was performed leading to a good reproduction of the nu8 + nu9 band with a rms uncertainty of 0.00046 cm-1 . A set of rovibrational constants for nu8 + nu9 were accurately determined, while for nu6 + nu7 the rotational constant B and the band origin were obtained.
