 Again using the idealistic simplest case a subset of dye molecules suspended in solution that have a mono-exponential fluorescence lifetime formula_7 and an initial anisotropy r0=0.4.If the sample is excited with a pulsed vertically orientated excitation source then a single decay time formula_7 should be measured when the emission polarizer is at the magic angle.If the emission polarizer is vertically polarized instead two decay times will be measured both with positive pre-exponential factors, the first decay time should be equivalent to formula_7 measured with the unpolarized emission set-up and the second decay time will be due to the loss of fluorescence as Brownian motion results in dye molecules moving from an initial vertical polarized configuration to an unpolarized configuration.