Fourier transform infrared spectroscopy of the BH3 ν3 band

Abstract

The gas‐phase infrared spectrum of the BH₃ ν₃ band was observed in the 2600 cm⁻¹ region by a Fourier transform infrared spectrometer. The borane molecule was produced with a discharge in a B₂H₆ and He mixture. The spectral pattern was consistent with the D_3h structure of borane. The observed spectrum between 2450–2730 cm⁻¹ was analyzed to determine band origins, rotational constants, and centrifugal distortion constants. The ν₃ band origins of ¹¹BH₃ and ¹⁰BH₃ were 2601.5743(15) and 2615.7935(21) cm⁻¹, respectively, with one standard deviation in parentheses. The B–H bond length was determined for the first time experimentally to be r₀=1.190 01(1) Å from the ground state rotational constant B₀.