The role of London forces in defining noncentrosymmetric order of high dipole moment high hyperpolarizability chromophores in electrically poled polymeric thin films

被引:234
作者
Dalton, LR [1 ]
Harper, AW [1 ]
Robinson, BH [1 ]
机构
[1] UNIV WASHINGTON, DEPT CHEM, SEATTLE, WA 98195 USA
关键词
D O I
10.1073/pnas.94.10.4842
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Graphs of second harmonic generation coefficients and electro-optic coefficients (measured by ellipsometry, attenuated total reflection, and two-slit interference modulation) as a function of chromophore number density (chromophore loading) are experimentally observed to exhibit maxima for polymers containing chromophores characterized by large dipole moments and polarizabilities. Modified London theory is used to demonstrated that this behavior can be attributed to the competition of chromophore applied electric field and chromophore-chromophore electrostatic interactions, The comparison of theoretical and experimental data explains why the promise of exceptional macroscopic second-order optical nonlinearity predicted for organic materials has not been realized and suggests routes for circumventing current limitations to large optical nonlinearity, The results also suggest extensions of measurement and theoretical methods to achieve an improved understanding of intermolecular interactions in condensed phase materials including materials prepared by sequential synthesis and block copolymer methods.
引用
收藏
页码:4842 / 4847
页数:6
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