Effect of Fluorescence Polarization on Fluorescence Intensity and Decay Measurements

Abstract

When a fluorescent system is excited with an unpolarized light and its emission is detected without a polarizer, as in the most common fluorescence instruments, the emission intensity displays a typical anisotropic distribution which is directly related to the degree of polarization of the emission. This effect may introduce an error of up to 20% in all steady state and dynamic fluorescence measurements and is discussed in detail for fluorescence intensity and decay measurements. It is shown that when the fluorescence is detected at an angle of 55° or 125° to the direction of excitation the effect of polarization is totally abolished.