Figure 4 | Scientific Reports

Figure 4

From: Observation of the linewidth broadening of single spins in diamond nanoparticles in aqueous fluid and its relation to the rotational Brownian motion

Figure 4

(a) Schematic illustration of the gated photon counting for the ODMR measurements. The APD detection is gated for microwave irradiation ON and OFF. The APD gate width is 200 μs common to the both gates, giving \({\rm{\Delta }}{I}_{{\rm{PL}}}={I}_{{\rm{PL}}}^{{\rm{ON}}}/{I}_{{\rm{PL}}}^{{\rm{OFF}}}\). The repetition rate of the gating (including laser off time of 100 μs) is 2 kHz. The 532-nm green laser irradiation is continuously ON during these gating periods. 532: 532-nm green laser pulse. MW: microwave pulse. Sig: photon counting while the microwave is ON. Ref: photon counting while the microwave is OFF. (b) ODMR spectra of the nanodiamond indicated by the dashed circle (Fig. 3) when it is fixed on the coverslip and (c) is about to detach. The blue solid lines in (b and c) are the Lorentzian fits to the data, and the red dashed lines in (b) are the 2-peak components of the fitting. The olive dashed line in (c) is the reproduced curve for the minor peak, which is almost buried in the noise, calculated by taking account of the reduction of the main peak contrast (or area).