Single molecule fluorescence techniques photon counting histograms

In the related photon counting histogram technique, a histogram of the intensity of fluorescence from individual molecules is collected as molecules diffuse through the focal volume of a confocal microscope [278-280]. If the sample contains a mixture of molecules with different fluorescence properties, the histogram can reveal the relative amplitude of the fluorescence from a single molecule of each class, as well as the number of molecules in each class. 

---