Rotational tunneling in phase III of CD4

High resolution inelastic neutron scattering has been used to study rotational tunneling in CD4 III. Measurements have been performed with an energy resolution of δE = 0.36 μeV and energy transfers E of up to EMAX = 36 μeV. The complex spectrum consists of at least eight lines with energies Ei?8 μeV. The data can only be explained assuming a superposition of several single molecule spectra. Four different models with up to five inequivalent sites describe the data almost equally well. These models have been used in an attempt to explain the tunneling spectra of CH4 in a CD4 matrix.