Analysis of torsional spectra of molecules with two internal C3v rotors. II. Far infrared and low frequency Raman spectra of dimethylether isotopes

Abstract

The torsional far infrared and Raman spectra of gaseous CH3OCH3, CD3OCH3, and CD3OCD3 are presented. They are analyzed using a computer program which is based on the results of an extensive investigation of the isometric groups and of the symmetry groups of the rotation–internal rotation Hamiltonians of a series of semirigid two‐top models. Four or more Fourier coefficients of the potential functions in two variables could be determined for each isotope. Strong evidence was found for Fermi‐resonance‐type interactions with the COC bending mode.