Observation of CH3 tunneling manifold by level-crossing NMR.

Abstract

Rotational tunneling spectra of strongly hindered C${\mathrm{H}}_{3}$ torsional oscillator pairs which do not interact among themselves are reported. These results are obtained by applying the Zeeman-tunneling level matching method in the proton spin rotating frame. Two noninteracting C${\mathrm{H}}_{3}$ particle manifolds explain the observed C${\mathrm{H}}_{3}$ multiquantum transitions driven by intramolecular and/or intermolecular dipole-dipole interactions to first or second order. Level matching resonances indicating that two methyl groups simultaneously undergo a symmetry breaking transition are observed. The dependencies of level-crossing transitions on Zeeman-tunneling mixing time and tilt angle are reported.