Widefield relaxometry with phosphorus doped NV sensor

摘要

Nitrogen vacancy (NV) centers have amassed considerable interest as biologically compatible magnetometers. NVcenters are point defects consisting of a substituted nitrogen adjacent to a vacancy in diamond’s lattice. These defectsexhibit an optically addressable magnetic field response at room temperature, a process known as optically detectedmagnetic resonance (ODMR). We take advantage of the imbalanced probability of the excited magnetic spin ±1 state totransition to the ground magnetic spin 0 state through an intermediate secondary singlet pathway in NV color centers.This alternative intersystem relaxation response can provide a source of contrast for live-cell imaging with potentialnano-scale resolution, as well as for measuring low concentrations of paramagnetic ions. Paramagnetic moleculesgenerate random magnetic field fluctuations which result in a non-zero RMS field. These fluctuations can induce spinrelaxation in NVs in the near field of such paramagnetic molecules. This technique is applied at room temperaturewithout microwave control frequencies or induced magnetic fields. The relaxation time for a bulk NV sensor doped withphosphorus was measured, which compared well with referenced values. Phosphorus doping in NV diamond allows theexcitation wavelength to be red shifted for a less cytotoxic effect. ODMR spectra were acquired with a helium neon(HeNe) laser.