Charge stability of nitrogen-vacancy color centers in organic nanodiamonds

The negatively-charged nitrogen-vacancy (NV) color center in diamond undergoes stochastic charge state transitions between the negatively charged state (NV- ) and the neutral charged state (NVo) upon optical illumination. While the negative charge state is normally preferred for magnetic sensing, optically-controlled switching between charges states is often desirable, for example in super-resolution imaging. The concentration of electron donor impurities in (bulk/nano) diamond crystals determine how much optical control can be exercised over the NV- and NVo charge states. Here we report how the growth speed of nanodiamonds (NDs) can control the concentration of substitutional nitrogen (P1) donors, ranging from highly pure to highly doped diamond. Hence by growth temperature, it is possible to tune the stability of the NV charge state to optimally match the intended application. This work has many promising bio-sensing applications, especially for super-resolution magnetic-sensing with the NV color center. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement