Contribution of antisymmetric nonresonant vibrational Raman scattering to the ν16 and ν17 bands of tetrahydrofuran

The contribution of antisymmetric nonresonant vibrational Raman scattering to the totally symmetric ν16 and ν17 bands of tetrahydrofuran is theoretically and experimentally studied. In nonresonant Raman spectra, the depolarization ratios of ν16 and ν17 combination bands with pseudorotation have been found to be ρ ∼ 0.75, far larger than those of ordinary totally symmetric vibrational bands. By using time-reversal symmetry and group theory, theoretical results show that the antisymmetric transition polarizabilities induced by pseudorotation-vibronic coupling make an important contribution to the depolarization ratios of the ν16 and ν17 bands and become one order of magnitude smaller than or the same order of magnitude as the symmetric ones.