Treatment of lab-grown diamond by electron irradiation and annealing has enabled quantum sensors based on negatively-charged nitrogen-vacancy (NV -) centers to demonstrate record sensitivities. Here we investigate the irradiation and annealing process applied to 28 diamond samples using a new ambient-temperature, all-optical approach. As the presence of the neutrally-charged nitrogenvacancy (NV 0 ) center is deleterious to sensor performance, this photoluminescence decomposition analysis (PDA) is first employed to determine the concentration ratio of NVto NV 0 in diamond samples from the measured photoluminescence spectrum. The analysis hinges on (i) isolating each NV charge state's emission spectrum and (ii) measuring the NVto NV 0 emission ratio, which is found to be 2.5˘0.5 under low-intensity 532 nm illumination. Using the PDA method, we measure the effects of irradiation and annealing on conversion of substitutional nitrogen to NV centers. Combining these measurements with a phenomenological model for diamond irradiation and annealing, we extract an estimated monovacancy creation rate of 0.52˘0.26 cm -1 for 1 MeV electron irradiation and an estimated monovacancy diffusion coefficient of 1.8 nm 2 /s at 850˝C. Finally we find that irradiation doses Á 10 18 e -/cm 2 deteriorate the NVdecoherence time T2 whereas T1 is unaffected up to the the maximum investigated dose of 5ˆ10 18 e -/cm 2 . :1906.11406v1 [cond-mat.mes-hall] arXiv

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