High-Throughput Detection and Manipulation of Single Nitrogen-Vacancy Center's Charge in Nanodiamonds

TL;DR

This paper introduces a high-throughput, sensitive method for analyzing and manipulating the charge states of single nitrogen-vacancy centers in nanodiamonds, enabling advanced quantum sensing and biological imaging applications.

Contribution

It presents a novel two-color wide-field imaging technique for systematic, high-throughput analysis and reversible charge manipulation of NV centers in nanodiamonds.

Findings

Charge conversion of NV centers observed via fluorescence ratios

Lifetimes of NV charge states measured in nanodiamonds

Reversible NV charge manipulation by pH demonstrated

Abstract

The fluorescent nitrogen-vacancy (NV) defect in diamond has remarkable photophysical properties, including high photostability, which allows stable fluorescence emission for hours; as a result, there has been much interest in using nanodiamonds (NDs) for quantum optics and biological imaging. Such applications have been limited by the complexity and heterogeneity of ND photophysics. Photophysics of the NV center in NDs have been studied before, but the lack of a sensitive and high-throughput method has limited the characterization of NDs. Here is reported a systematic analysis of NDs using two-color wide-field epifluorescence imaging coupled to high-throughput single-particle detection of single NVs in NDs with sizes down to 5-10 nm. By using fluorescence intensity ratios, the charge conversion of single NV center (NV- or NV0) is observed and the lifetimes of different NV charge states in NDs is measured. The discovery of reversible manipulation of NV charge states by pH is also presented. In addition to provide another mechanism to control the NV charge state in nanodiamonds, our findings open the possibility to perform pH nanosensing with a non-photobleachable probe.