Inelastic neutron scattering studies and barriers to methyl rotation in alkali-metal methanesulphonate salts
Abstract
The “torsional” motion in the methanesulphonate ion (CH3SO3–) in its alkali-metal salts has been investigated by means of incoherent inelastic neutron scattering spectroscopy. Infrared and Raman spectra in the low-frequency region were also obtained to aid in assigning torsional modes. The Cs+ salt shows a single torsional band, while the other salts show several bands which may be assigned to torsions. A model which takes account of the coaxial motions of the SO3 and CH3 groups has been used to calculate values for the sum of the internal and external barriers which hinder reorientation of the CH3 group.