文档介绍：Fluorescence Polarization Light is a harmonic ic wave. When considering its interaction with matter we can in most cases neglect the ic part. The plain in which the electric vector E oscillates defines the polarization of light . Natural light contains randomly all possible orientations of electric vector Light propagation direction Unpolarized (random) light Polarization E B Ec nB? 2EI? an ponent that selects from passing light only ponent polarized in a given direction Unpolarized (random) mon polarizers: ? double refracting ( birefrigent ) calcite (CaCO 3 ) crystals- which ponents of light polarized in two perpendicular planes under different angles ? filters, which effectively absorb one plane of polarization (., Polaroid type-H sheets based on stretched polyvinyl alcohol impregnated with iodine) Polarizer Linear polarized light Polarizer I 0 I = I 0 /2 In 1920, F. Weigert discovered that the fluorescence from solutions of dyes was polarized. Specifically, he looked at solutions of fluorescein, eosin, rhodamine and other dyes and noted the effect of temperature and viscosity on the observed polarization. Wiegert discovered that polarization increased with the size of the dye molecule and the viscosity of the solvent, yet decreased as the temperature increased . He recognized that all of these considerations meant that fluorescenc e polarization increased as the mobility of the emitting species decreased . Polarization and dipole transitions Absorption: The probability of a transition of a molecule between two energetic levels (for example S 0? S 1 ) is proportional to cos 2?, where ? is the angle between the dipole moment of the transition and the direction of polarization of the excitation light. Emission of a point dipole is polarized in the direction of the dipole potential dipole orientation probability of excitation Photoselection : The phenomenon of ani