Optical saturation in fluorescence correlation spectroscopy under continuous-wave and pulsed excitation.
A detailed theoretical and experimental study of the dependence of fluorescence correlation measurements on optical excitation power due to optical saturation effects is presented. It is shown that the sensitivity of a fluorescence correlation measurement on excitation power becomes increasingly stronger for decreasing excitation power. This makes exact measurements or diffusion coefficients with fluorescence correlation spectroscopy rather difficult. A strong difference of this behavior for continuous-wave and pulsed excitation is found.
Gregor
Ingo
I
Institute for Biological Information Processing 1, Forschungszentrum Jülich, 52425 Jülich, Germany.
Patra
Digambara
D
Enderlein
Jörg
J