Despite the numerous experimental and theoretical studies on the negatively charged N vacancy center (NV−) in diamond and the predictions that the neutral N vacancy center (NV0) should have an S = ½  ground state, NV0 had not previously been detected by electron paramagnetic resonance. New electron paramagnetic resonance data were reported for a trigonal N-containing defect in diamond with an S = 3/2 excited state populated via optical excitation. Analysis of the spin Hamiltonian parameters and the wavelength dependence of the optical excitation led to assignment of this S = 3/2 state to the 4A2 excited state of NV0. This identification, together with an examination of the electronic structure of the N-vacancy centers in diamond, provided a plausible explanation for the lack of observation (to date) of an electron paramagnetic resonance signal from the NV0 ground state.

Electron Paramagnetic Resonance Studies of the Neutral Nitrogen Vacancy in Diamond. S.Felton, A.M.Edmonds, M.E.Newton, P.M.Martineau, D.Fisher, D.J.Twitchen: Physical Review B, 2008, 77[8], 081201(R) (4pp)