Influence Of Transition Electric Dipole Moment And Magnetic Dipole Moment On Circularly Polarized Light

Circularly polarized luminescence（CPL）refers to the phenomenon of left-handed or righthanded circularly polarized light emitted by chiral luminescent materials,which is usually produced by materials with chiral molecular structure.Chiral molecules are those that do not overlap under mirror symmetry operations,including left-handed and right-handed bodies.When chiral molecules are excited by an external force,such as absorbing light energy or applying an electric field,they produce circularly polarized light.Materials with circularly polarized luminescence properties have important applications in 3D display,optical storage,optical anti-counterfeiting and asymmetric synthesis.For circularly polarized luminescent materials,how to improve the asymmetry factor(g_lum)has always been a topic of concern.In organic CPL materials,the molecular transition electric dipole moment（μ）is generally much greater than the transition magnetic dipole moment（m）,and their ratio and Angle directly determine the size of g_lum.Too large a difference in ratio is not conducive to the improvement of g_lum.It is difficult to obtain these microscopic data by experimental methods,so this thesis simulates the fluorescence emission of chiral molecules under different molecular structures and different applied electric fields by quantum chemical computation,and finds the variation law ofμ,m,and g_lum.The research content of this thesis is as follows:The main research content and innovation points are as follows:（1）The fluorescence emission of five chiral molecules with different structures in aqueous solution and cluster were calculated by the method of theoretical chemical calculation,and the results were characterized and the mathematical formulas were analyzed.The changes of μ and m of different molecular structures under fluorescence emission conditions of aqueous solution and cluster were found respectively.These rules can provide theoretical guidance for the design of high g_lum chirality molecules.（2）The fluorescence emission of molecules under different electric field direction and intensity is simulated by quantitative calculation,and the correct values of μ,m,g_lum are obtained.It is found that when the applied electric field direction is parallel to the molecular polarity direction,μ and m are decreasing,but the influence of the applied electric field in the same direction and the opposite direction on μ is different,which will cause the reduction of μ to change,resulting in the change of μ/m and the Angle between μ-m,and then determine the electric field intensity at the maximum g_lum value.