Electron Spin Resonance of NV(–)-Centers in Synthetic Fluorescent Diamond Microcrystals under Conditions of Optical Spin Polarization

Electron paramagnetic resonance (EPR) spectra of synthetic diamond microcrystals with NV(‒)‑centers have been studied. It is shown that under the conditions of irradiation of the material with the light of a xenon lamp at low temperatures 100 K, the intensities of the EPR signals corresponding to the “forbidden” (Δms = 2) and low field allowed (Δms = 1) transitions are amplified several times, while the EPR signals from paramagnetic nitrogen and impurity nickel in the charge state –1 practically do not change. This is due to a change in the population of levels of the ground triplet state of the NV(–)-center and the optical polarization of spins in the state ms = 0 of the triplet level.