Detection and decoherence of level-crossing resonances of 8 Li in Cu

Level-crossing resonances are observed for spin-polarized ${}^{8}$Li in copper at 200 K. The positions of the resonances as a function of magnetic field and crystal orientation are a precise measure of the induced quadrupolar interaction on the nearest-neighbor Cu spins and provide unambiguous evidence that ${}^{8}$Li occupies a substitutional site. The resonances are detected as enhancements in the ${}^{8}$Li spin relaxation rate and are much broader than predicted from a static spin Hamiltonian. A strong collision model is used to extract a decoherence time as a result of the dipolar coupling of the ${}^{8}$Li-Cu subsystem to the surrounding nuclear spin bath.