Raman spectra of asymmetric top molecules. Part 2.—ΔK=± 2 transitions in the rotational spectrum of butadiene

Abstract

ΔK= 2 transitions have been observed in the pure rotational Raman spectrum of butadiene. Rotational constants were determined for the ground state, ν13 torsional mode, ν24 bending mode and the 2ν13 torsional state. Evidence of a Coriolis interaction between ν13 and ν24 was found and the rotational constants derived from those two states were corrected for this specific interaction. A–text-decoration:overlineB values obtained for the four states were 1.247 82 ± 0.000 09 cm–1, 1.226 70 ± 0.000 24 cm–1, 1.2703 ± 0.0010 cm–1 and 1.167 ± 0.002 cm–1 for the ground, ν13, ν24 and 2v13 vibrational states respectively. In addition DK distortion constants of (3.61 ± 0.18)× 10–6 cm–1 and (2.6 ± 0.5)× 10–6 cm–1 were determined for the ground and ν13 states respectively.