Should also do the fitting with the model that fits Kon and Koff separatelly.
Model is in the supplementary data of the paper
"Direct Measurement of Association and Dissociation Rates of DNA Binding in Live Cells by Fluorescence Correlation Spectroscopy"
by
Ariel Michelman-Ribeiro, Davide Mazza, Tilman Rosales, Timothy J. Stasevich, Hacene Boukari, Vikas Rishi, Charles Vinson, Jay R. Knutson and James G. McNally