FCCS curves in the presence of non-fluorescent binding partners. All fluorophores A are assumed to be fluorescent (pa = 1), while the probability of fluorophore B to be fluorescent ranged from 0-1 (pb = 0 ... 1). We assumed identical detection volumes for both channels with axial radii of 260 nm, and axial radii of 1.3 μm, corresponding to observation volumes of 0.5 fl; the brightness of the two particles was set to 1500 counts/second in their respective channel, and 10% cross-talk from particle a into the detection channel B and 1% cross-talk of particle b into detection channel A; the diffusion times for the two particles were set to τDa = 3 ms, τDb = 0.3 ms.
