Figure 10.

Dependence of the average FRET efficiency on the average distance between fluorophores for the different ranges of the distance diffusion for the molecules with fast rotational diffusion and fixed distance (solid line), fast rotational diffusion and fast distance diffusion (dashed lines), and fast rotational diffusion and slow distance diffusion (dotted lines). The FRET efficiency was numerically calculated for the uniform distance distributions over $\pm 0.2R_0\left(\frac{2}{3}\right)$ and $\pm 0.5R_0\left(\frac{2}{3}\right)$ by averaging FRET efficiency over distance distribution for the slow distance diffusion case and by averaging the kinetic rate and calculating FRET efficiency from it for fast distance diffusion. The smaller width of the distance distribution corresponds to the smaller deviation from the case with fast rotational diffusion and fixed distance.