Optimization of the Double Electron–Electron Resonance for C‐Centers in Diamond

NV centers in diamond recommend themselves as good sensors of environmental fields as well as detectors of diamond impurities. In particular, C-centers, often also called ${{p}_{1}}$-centers, can be detected via double electron-electron resonance. This resonance can be used to measure the C-center concentration. Here, we measured the concentration of C-centers in several diamond plates and investigated the influence of the free precession time of the NV center on the observed contrast in the measured double electron-electron resonance spectrum. The dependence of the resonance amplitudes and widths on the concentration of C-centers as well as the length of the combined C-center driving and NV-center $\pi$-pulse is also discussed. The optimal contrast-free precession time was determined for each C-center concentration, showing a strong correlation with both the concentration of C-centers and the NV-center ${{T}_{2}}$ time.