Electron paramagnetic resonance studies of the neutral nitrogen vacancy in diamond
S. Felton, A. M. Edmonds, M. E. Newton, P. M. Martineau, D. Fisher, and D. J. Twitchen

Despite the numerous experimental and theoretical studies on the negatively charged nitrogen vacancy center ({\nvneg}) in diamond, and the predictions that the neutral nitrogen vacancy center ({\nvneut}) should have an $S= \frac{1}{2}$ ground state, {\nvneut} has not previously been detected by Electron Paramagnetic Resonance (EPR). We report new EPR data on a trigonal nitrogen containing defect in diamond with an $S = \frac{3}{2}$ excited state populated via optical excitation. Analysis of the spin Hamiltonian parameters and the wavelength dependence of the optical excitation leads to assignment of this $S = \frac{3}{2}$ state to the $^4$A$_2$ excited state of {\nvneut}. This identification, together with an examination of the electronic structure of the NV centers in diamond provides a plausible explanation for the lack of observation (to-date) of an EPR signal from the {\nvneut} ground state.

© 2008 The American Physical Society.