15min:

R. L. SAMS, T. A. BLAKE AND S. W. SHARPE, Pacific Northwest Laboratory, P.O. Box 999, Battelle Boulevard, Richland, WA 99352; J.-M. FLAUD, Laboratoire de Photophysique Moléculaire, CNRS, Univ. de Paris-Sud, B\^at. 210, Orsay 91405, France; W. J. LAFFERTY, Optical Technology Division, NIST, Gaithersburg, MD 20899.

Using high resolution Fourier transform spectra, a thorough analysis of the ₁₄ c-type band, and ₁₇ and ₁₈ a-type bands of both ¹¹B₂H₆ and ¹⁰B¹¹BH₆ has been carried out. The analysis and the determination of the upper state Hamiltonian constants proved to be difficult since the rotational levels of the mains bands are strongly perturbed by nearby dark states. However, in the case of the ₁₈ band of ¹⁰B¹¹BH₆, it was possible to assign a few resonating lines of the ₅+₁₀ band which borrow their intensity from the corresponding ₁₈ lines. Accordingly it was possible to derive a precise band center for ₅+₁₀. Finally a comparison of the band centers determined in this work with those estimated in the literature will be presented.