Alba FCS provides two fundamental and complementary features to obtain information about the molecular dynamics of the sample under observation: the autocorrelation function and the photon counting histogram (PCH). In the measurement shown above, solutions of different concentrations of Coumarin and Rhodamine110 were prepared and exposed to 2-photon excitation at 780-nm. A global PCH analysis was then performed on the data. From these data, the following parameters can be determined: brightness and number of molecules in the excitation volume.