M. Tomaselli et al., Evidence for orientational tunneling of CO intercalated in C-60: A nuclearmagnetic resonance study, J CHEM PHYS, 113(13), 2000, pp. 5141-5144
We characterize the low-temperature dynamics of CO intercalated in C-60 usi
ng NMR spectroscopy. CO in C-60 is found to be dynamically inhomogeneous be
low 30 K: The (CO)-C-13 line shapes reflect a dynamic disorder to static di
sorder transition, with only quantum tunneling among equivalent orientation
s in a local S-6 symmetry potential remaining. The increased hindrance of t
he CO motion cannot be reconciled with common expectations of a homogeneous
, thermally activated jumplike reorientation process, but is well accounted
for in a model of orientational pinning due to asymmetric distortions of t
he cage potential. (C) 2000 American Institute of Physics. [S0021-9606(00)7
0837-3].