Resolved nuclear hyperfine structure of muonated free radicals using level crossing spectroscopy

The nuclear hyperfine parameters of the muonated free radical C6F6Mu have been measured using a novel level crossing resonance technique. Slow oscillations of the muon spin in a large longitudinal magnetic field or frequency splittings in transverse field occur at particular field values where there is a zeroth order degeneracy in the muon-nuclear-electron hyperfine levels. A resonant-like effect on the μSR spectrum as a function of magnetic field is observed. The positions of level crossing resonances allow an accurate determination of the magnitude and sign of the nuclear hyperfine parameters relative to the muon hyperfine parameter