Far-Infrared Spectrum of Tetrahydrofuran: Spectroscopic Evidence for Pseudorotation

Abstract
The infrared spectra of tetrahydrofuran and tetrahydrofuran‐d8 are reported between the limits 10 and 300 cm−1. The rather complex spectrum obtained for this molecule is interpreted in terms of the theory of pseudorotation of a puckered ring. The spectroscopically derived value of the parameter mq02 is (8.56±0.13)×10−40 g·cm2 for the ground, v=0, radial state and (8.48±0.15)×10−40 g·cm2 for the excited, v=1, radial state.