The rotational dynamics of NH3 in the ammoniated fulleride (NH3)K3C60 are studied by the inelastic neutron scattering technique. Well-defined excitations appear in the low-energy spectra at 1.5 K as a broad band centered at ∼350 μeV with shoulders at ∼240 and 590 μeV. The temperature dependence of their intensities, energies, and widths is consistent with their assignment to rotational tunneling transitions of the NH3 molecule. The estimated barrier of the threefold hindrance potential to rotation of the H atoms about the K-N axis is ∼5.7 meV. The existence of minority hindering sites with both larger (∼8 meV) and smaller (∼2 meV) torsional barriers shows that orientational disorder effects survive in (NH3)K3C60 even at low temperatures.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry