Chemical Physics 110(18): 9145-9150
Theory of single-molecule fluorescence spectroscopy of two-state systems.
A. M. Berezhkovskii
Center for Information Technology, National Institutes of Health, Bethesda, Maryland 20892
and Karpov Institute of Physical Chemistry, Ul. Voronstovo Pole 10, 103064 Moscow, K-64, Russia
Attila Szabo
Laboratory of Chemical Physics, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
G. H. Weiss
Center for Information Technology, National Institutes of Health, Bethesda, Maryland 20892
Abstract
We derive an explicit expression for the probability density of the amplitudes of the biexponential fluorescence decay of a two-state system observed in single-molecule experiments of finite duration T. The shape of the probability density of the amplitudes depends on (K1 + K2)T, where the Ki are the interconversion rate constants. It approaches a delta function in the limit T -> infinity. When the interconversion rates in the ground and excited states differ, the single-molecule and bulk experiments will give different results even in the limit of infinite duration of the experiment.