15min:

R. L. SAMS, T. BLAKE AND S. W. SHARPE, Pacific Northwest National Laboratory, PO Box 999, Battelle Blvd. Richland, WA 99352; J.-M. FLAUD, Lab. Photophysique Moleculaire, CNRS, Universite Paris-Sud, Bat. 210, 91405 ORSAY, Cedex, France; W. J. LAFFERTY, Optical Physics Division, NIST, Gaithersburg, MD 20899 and Instituto de Estructura de la Materia, C.S.I.C., Serrano 121, 28006 Madrid, Spain..

We are in the process of recording and analyzing all of the infrared active bands of B₂H₆, the simplest of the hydrogen-bridged borane compounds, with the goal of determining the frequencies of the IR forbidden modes in this very symmetric (D_2h) molecule by means of anharmonic interactions. The spectra were obtained on a Bruker 120HR FT spectrometer with a spectral resolution of 0.002 cm^-1. The sample contained boron in natural abundance (~80% ¹¹B; 20% ¹⁰B) and, therefore, the abundance of ¹¹B₂H₆, ¹⁰B¹¹BH₆ and ¹¹B₂H₆ was 64%, 32% and 4% respectively. With the resolution available, the spectra of the two most abundant isotopomers were readily assignable. At this point, the ₁₄ (c-type) and ₁₇ (a-type) bands have been assigned for both the ¹¹B₂H₆ and ¹¹B¹⁰BH₆ isotopic species and ground state and upper state constants obtained. Both bands exhibit small perturbations. A mixed r_s-r₀ structure for diborane has been obtained.