Electron spin resonance detection and identification of nitrogen centers in nanodiamonds

Individual nitrogen centers N⁰ and nitrogen pairs N₂⁺ have been detected and identified in natural diamond nanocrystals by means of the high-frequency electron spin resonance method. The N⁰ nitrogen centers have been observed in synthetic diamond nanocrystallites with a size of less than 10 nm produced by high-temperature high-pressure sintering of detonation nanodiamonds. Thus, the possibility of the stable state of impurity nitrogen atoms in diamond nanoparticles has been demonstrated.