Conjugated chains optical responses

By extension one may say that the power laws (5-7) which determine the magnitude of the linear and nonlinear optical coefficients are consequences of this strong electron-lattice coupling. We now make the conjecture that the time response of these coefficients is severely affected by the dynamics of the electron-lattice coupling in conjugated chains when two or more resonant chemical structures can coexist this is the case for many of the organic chains of Figure 2. 

Up to now, many conjugated polymers have been found to possess large and very rapid third-order nonlinear optical response, which originates from the one-dimensionally delocalized ji-conjugation system along the polymer chain. Their application to the all optical signal processing devices has been expected. 

Multiple Heck reactions have also been applied in a number of ways to prepare polymers (Scheme 40). One-dimensionally 7r-conjugated polymers are attractive materials because of their optical and electrical properties resulting from 7r-electron delocalization along their main chains. Among these, poly(p-phenylenevinylene) (PPV) shows high electrical conductivity, large non-linear optical responses, and electroluminescent activity. One approach... 

ELECTRONIC ORIGIN OF SECOND ORDER NONLINEAR OPTICAL RESPONSES IN CONJUGATED LINEAR CHAIN STRUCTURES AND HIGHLY CHARGE CORRELATED tt-ELECTRON STATES... 

Faster computers and development of better numerical algorithms have created the possibility to apply RPA in combination with semiempirical Hamiltonian models to large molecular sterns. Sekino and Bartlett - derived the TDHF expressions for frequency-dependent off-resonant optical polarizabilities using a perturbative expansion of the HF equation (eq 2.8) in powers of external field. This approacii was further applied to conjugated polymer (iialns. The equations of motion for the time-dependent density matrix of a polyenic chain were first derived and solved in refs 149 and 150. The TDHF approach based on the PPP Hamiltonian - was subsequently applied to linear and nonlinear optical response of neutral polyenes (up to 40 repeat units) - and PPV (up to 10 repeat units). " The electronic oscillators (We shall refer to eigenmodes of the linearized TDHF eq with eigenfrequencies Qv as electronic oscillators since they represent collective motions of electrons and holes (see Section II))... 

We should point out that the off-resonance response of polythiophene (about 10 " e.s.u.) is of the same order of magnitude of other conjugated polymers indicating that the nonlinear optical response of a conjugated chain does not depend... 

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