It was shown that the spin-selective photo-kinetics of the substitutional N atom plus vacancy (NV) defect center, which had recently been clarified by low-temperature fine-structure resolved experiments on individual NV centers in nanocrystals, were behind the optical alignment of the electron spin of the center in the ground 3A state. This permitted the interpretation of the complicated hole/anti-hole burning spectra for NV ensembles in samples with a high NV content.

NV Centers in Diamond - Spin-Selective Photokinetics, Optical Ground-State Spin Alignment and Hole Burning. A.P.Nizovtsev, S.Y.Kilin, F.Jelezko, I.Popa, A.Gruber, J.Wrachtrup: Physica B, 2003, 340-342, 106-10