First High-Resolution Infrared Observation of the Symmetry-Forbidden nu(5) Band of (10)B(2)H(6).

Spectra of (10)B monoisotopic diborane, B(2)H(6), have been recorded at high resolution (2-3 x 10(-3) cm(-1)) by means of Fourier transform spectroscopy in the region 700-1300 cm(-1). A thorough analysis of the nu(18) a-type, nu(14) c-type, and nu(5) symmetry-forbidden band has been performed. Of particular interest are the results concerning the nu(5) symmetry-forbidden band, which is observed only because it borrows intensity through an a-type Coriolis interaction with the very strong nu(18) infrared band located approximately 350 cm(-1) higher in wavenumber.

The nu(2) Bands of the Deuterated Species D(2)Se and HDSe.

For the first time D(2)Se and HDSe as (80)Se monoisotopic and natural material were studied in the region of the nu(2) fundamental vibration by high-resolution (0.0033 cm(-1)) Fourier transform infrared spectroscopy. For D(2)Se which is an asymmetric rotor with C(2v) symmetry the nu(2) band is of B type while for HDSe (C(s) symmetry) it is a hybrid band, and both A- and B-type transitions were observed.

The Ground State of D(2)Se and HDSe.

Ground state rotational constants of D(M)(2)Se and HD(M)Se, M = 76, 77, 78, 80, and 82, have been determined up to octic centrifugal distortion terms from ground state combination differences. These were obtained from rotational analyses of the nu(2), nu(1), and nu(3) bands both of natural and (80)Se monoisotopic material recorded with a resolution of ca. 3 x 10(-3) cm(-1).