Extended Data Fig. 6: Kinetics of the electronic states.
From: Single-spin resonance in a van der Waals embedded paramagnetic defect
a, Energy level diagram used for modeling. b, Fluorescence autocorrelation measurement for longer time scales. The solid curve is a four parameter fit. The extracted time scale is indicated on the curve c, Fluorescence intensity dependence on the excitation laser power. The arrow indicates the laser power for which most measurements were carried out. Otherwise the power level is stated. The solid curve is a parabolic fit, the dashed line represents the linear component of the fit. d, Record of the PL intensity as a function of the delay time the two excitation sequences shown in the inset. In comparison with the behavior of the PL intensity during sequence 1, the fluorescence saturates at a lower value for simultaneous excitation of laser and MW radiation (sequence 2). This suggests shelving into a long lived metastable state during the initial laser excitation pulse in sequence 1. e, Fluorescence recovery curves for the different pulse sequences shown in the inset. f, Same as (e) but for longer delay times. The data indicate a lifetime of the long lived (ll) metastable state greater than 20 ms. g, The re-pump process is probed with the sequences shown in the inset. During sequence 2 the population is pumped into the ll state by the initial combined MW and laser pulse and subsequently repumped into state e2 during the probe laser pulse of variable width before the final fixed readout pulse. In contrast, during sequence 1 the population is not pumped into the ll state. The recovery of the ground state population due to the laser re-pump mechanism in the absence of MW is evident. The solid line is a simulation based on the energy level diagram model.
