Photon counting histograms for diffusing fluorophores.
The theory of photon counting histograms for fluorescent molecules diffusing through a laser spot is presented. Analytic expressions for the factorial cumulants of photon counts are obtained. For an arbitrary counting time window, it is shown how the exact histograms can be obtained by solving an appropriate reaction-diffusion equation. Our formalism reduces correctly when the molecules are immobile. The approximation used in fluorescence intensity multiple distribution analysis (FIMDA) is tested against the exact numerical solution of the problem. FIMDA works very well for a wide range of parameters except for small concentrations and long time windows.
Gopich
Irina V
IV
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA. gopich@nih.gov
Szabo
Attila
A
D000465:Algorithms; D004058:Diffusion; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D017785:Photons; D012996:Solutions
D005456:Fluorescent Dyes; D012996:Solutions