Figure 1

(Color online) Spectra from a typical switching NC, recorded at six different excitation powers $[(2.0,3.2,5.0,7.2,11,20)\times {10}^3\mathrm{W}∕{\mathrm{cm}}^2]$, are shown in order in (a)–(f). The integration time of $2\mathrm{s}$ is used for this measurement. The brightness represents the intensity, the horizontal axis is time, and the vertical axis is emission energy. (g) The integration for 26 measurements (each measurement having a $2\mathrm{s}$ integration time) when the NC stays in the same state. The energy difference between the two states is $5.6\mathrm{meV}$. (h) The intensity vs time plots for (a)–(f). The (blue) thin line is for the high energy state and the red (bold) line is for the low energy state. (i) The characteristic switching frequency vs excitation power.Reuse & Permissions

Figure 2

(Color online) Spectra from another NC were recorded continuously with an integration time of $0.5\mathrm{s}$. The emission peak randomly shifts with small energy changes between 2.099 and $2.108\mathrm{eV}$.Reuse & Permissions

Figure 3

(Color online) Spectra from a NC were recorded continuously with an integration time of $2\mathrm{s}$ each. (a)–(c) show that in some NCs, higher laser intensity not only increases the switching frequency but also makes the states move randomly. In addition, the figure shows that there is an additional peak in the lower energy side. The energy difference from the exciton peak is $22.7\mathrm{meV}$.Reuse & Permissions

Figure 4

(Color online) Spectra from a NC were recorded continuously with an integration time of $30\mathrm{s}$ each and constant temperature and excitation power. We used a $30\mathrm{s}$ integration time for each frame to see the lower energy peaks which are weaker than the exciton peak. Spectrum jitter allows us to group spectral transitions from individual NCs. The energy differences between the main line and the satellite lines are 22.7, 25.8, 45.4, and $48.5\mathrm{meV}$.Reuse & Permissions