Observation of Atomlike Nitrogen in Nitrogen-Implanted Solid ${\mathrm{C}}_{60}$

A new paramagnetic defect in solid ${\mathrm{C}}_{60}$ was produced by nitrogen implantation in solid ${\mathrm{C}}_{60}$. The hyperfine splitting and the isotope effect unambiguously show that the paramagnetic center contains one nitrogen nucleus. The hyperfine interaction is isotropic, its value is comparable to that of the free nitrogen atom, and the spin of the electron system is $S=3/2\mathrm{}$, as in atomic nitrogen. The complex responsible for this center is soluble in toluene and C${\mathrm{S}}_2$ and is stable. We suggest that the complex consists of nitrogen inside ${\mathrm{C}}_{60}$.