  A new variant of the superconducting fulleride $\mathrm{Rb_{3}C_{60}}$ is
presented, with $\mathrm{^{3}He}$ atoms encapsulated in the $\mathrm{C_{60}}$
cages. The $\mathrm{^{3}He}$ nuclei act as sensitive NMR probes embedded in the
material. The superconducting and normal states are characterised by
$\mathrm{^{3}He}$ NMR. Evidence is found for co-existing vortex liquid and
vortex solid phases below the superconducting transition temperature. A strong
dependence of the spin-lattice relaxation time constant on spectral frequency
is observed in the superconducting state, as revealed by two-dimensional NMR
utilising an inverse Laplace transform. Surprisingly, this phenomenon persists,
in attenuated form, at temperatures well above the superconducting transition.
