Table 1.

Experimental advances in detection, identification, and characterization of sparse and single molecules in dilute solution by FCS

Utilization of a high-speed dedicated digital correlator for nearly real-time highly efficient determination of correlation functions

Reduction of the dark-current noise and improvement of the signal/shot noise with small area and high quantum efficiency avalanche photodiode (APD) detector

Reduction of the in-focus background by tight focusing to a small probe volume and marker wavelength selection

Reduction of out-of-focus background and improved probe volume definition by confocal detection

Elimination of the out of focus background and photo bleaching by two-photon excitation (TPE)

Avoiding Raman and Rayleigh scattering by TPE to reduce in-focus background