EPR investigation of atoms in chemical traps

Magnetic properties of atoms and molecular clusters encapsulated in fullerenes and other chemical traps are studied using various EPR and ENDOR techniques. From these results exceptional topological and electronic properties of these new compounds can be derived. Making use of the high symmetry at the site of the encased paramagnetic atom, details of the deformation of the spin density distribution resulting from the confinement are deduced. Dissolving N@C60 and N@C70 in a liquid crystal, the order parameter of the solute can be studied by invoking the fine structure interaction of confined nitrogen in its 4S3/2 ground state. Information about the interaction potential locating the neutral atoms at the cage centre is obtained from an analysis of the temperature dependence of the hyperfine coupling constant. Values deduced are in good agreement with vibrational frequencies calculated in harmonic approximation.