Figure 2

\(\pmb{T_{1}}\) common-mode rejection pulse sequences, example NV \(\pmb{^{-}}\) fluorescence, and example \(\pmb{T_{1}}\) decay. (a) Optical and microwave pulse sequence used for \(T_{1}\) measurements. The upper (green) rectangles show the optical excitation, while the lower (blue) one is the MW pulse. (b) Sketch of the related time dependence of population \(P_{0}(t)\) of the ground state \(m_{\mathrm{s}} = 0\). This state is predominantly responsible for the luminescence signal with (left panel) and without (right panel) the MW pulse. (c) Time dependence of the luminescence signals (at room temperature 293 K) at the beginning of the readout pulse with and without the MW pulse (left panel) and their difference (right panel). Subtraction of two subsequent recordings with and without the MW pulse for different delay times τ allows determination of the longitudinal relaxation time \(T_{1}\).