Long-Lived Ensembles of Shallow NV^– Centers in Flat and Nanostructured Diamonds by Photoconversion

Abstract

Shallow, negatively charged nitrogen-vacancy centers (NV – ) in diamond have been proposed for high-sensitivity magnetometry and spin-polarization transfer applications. However, surface effects tend to favor and stabilize the less useful neutral form, the NV 0 centers. Here, we report the effects of green laser irradiation on ensembles of nanometer-shallow NV centers in flat and nanostructured diamond surfaces as a function of laser power in a range not previously explored (up to 150 mW/μm 2 ). Fluorescence spectroscopy, optically detected magnetic resonance (ODMR), and charge-photoconversion detection are applied to characterize the properties and dynamics of NV – and NV 0 centers. We demonstrate that high laser power strongly promotes photoconversion of NV 0 to NV – centers. Surprisingly, the excess NV – population is stable over a timescale of 100 ms after switching off the laser, resulting in long-lived enrichment of shallow NV – . The beneficial effect of photoconversion is less marked in nanostructured samples. Our results are important to inform the design of samples and experimental procedures for applications relying on ensembles of shallow NV – centers in diamond.

Advances in nano- and microscale NMR spectroscopy using diamond quantum sensors

“…Material engineering to increase the NV spin density 22,48 Nanostructuring of diamond to enhance the surface area 144,154,155 Nanodiamonds containing NV centers 137,156,157 practical translation of this technology. Therefore, method of hyperpolarization could enable easy, low-cost, and efficient hyperpolarization for chemical analytics.…”

“…Material engineering to increase the NV spin density 22,48 Nanostructuring of diamond to enhance the surface area 144,154,155 Nanodiamonds containing NV centers 137,156,157 This journal is © The Royal Society of Chemistry 2022…”

Diamond surface engineering for molecular sensing with nitrogen—vacancy centers

“…163,172,173 This value can be even smaller for NV ensembles, 174 where tunneling between proximal NV centers and nearby nitrogen species may occur upon photoexcitation. 175 Multicolor illumination with near-infrared light 94,176,177 (resulting in spin-dependent charge transfer 178,179 ), doping, 180–182 and high laser powers 183 provide possible routes to increase the relative population of NV − . Moreover, spin-dependent ionization of NV − versus NV 0 states has been used as a resource for achieving single-shot spin readout.…”

Advances in nano- and microscale NMR spectroscopy using diamond quantum sensors

“…Material engineering to increase the NV spin density 22,48 Nanostructuring of diamond to enhance surface area 144,154,155 Nanodiamonds containing NV centers 137,156,157…”