Chromophores dipolar

Beverina L, Fu J, Leclercq A, Zojer E, Pacher P, Barlow S, Van Stryland EW, Hagan DJ, Bredas JL, Marder SR (2005) Two-photon absorption at telecommunications wavelengths in a dipolar chromophore with a pyrrole auxiliary donor and thiazole auxiliary acceptor. J Am Chem Soc 127 7282-7283... 

One key property of pyridylphosphole ligands is their heteroditopic nature. They possess two coordination centers with different stereo-electronic properties, which, in accordance with Pearson s antisymbiotic effect [42a], can control the orientation of a second chelating ligand in the coordination sphere of a square-planar d8-metal center [42b]. This property has been exploited in order to control the in-plane parallel arrangement of ID-dipolar chromophores [42d]. Phospholes... 

Fig. 11.6 Structures and NLO properties of two ferrocene-based dipolar chromophores [51, 52].

In electric-field poling, a guest dipolar chromophore and a chemically and optically passive host polymer (the chromophore can also be covalently tethered to the polymer [74] or incorporated into the main chain of the polymer) is heated to above the glass transition temperature, Tg, of the mixture. A large electric... 

Fig. 11.9 Thermal stability data for three dipolar chromophores illustrating the results of conformationally locking polyenes and of replacing dialkylamino groups with diaryla-mino groups. Td is the onset of weight loss...

For dipolar chromophores that are the subject of this chapter, only one component of the molecular hyperpolarizability tensor, Pzzz, is important. Thus, the summation in Eq. (8) disappears. Electric field poling induces Cv cylindrical polar symmetry. Assuming Kleinman [12] symmetry, only two independent components of the macroscopic second-order nonlinear optical susceptibility tensor... 

Clearly, a requirement for device quality second-order nonlinear optical materials is a noncentrosymmetric dipolar chromophore lattice. There are several ways by which such lattices have been achieved. With all methods, a force must... 

The model of polarizable dipolar chromophores suggests that the 3D nuclear reaction field of the solvent serves as a driving force for electronic transitions. Even in the case of an isotropic solute polarizability, two projections of the reaction field should be included the longitudinal (parallel to the difference solute dipole) component and the transverse (perpendicular to the difference dipole) component. The 8 function in Eq. [18] eliminates integration over only one of these two field component. The integral still can be taken analytically resulting in a closed-form solution for the Franck-Condon factor... 

For the experimental determination of the second-order first hyperpolarizability, some sort of non-centrosymmetry has to be present in the solution. This can be achieved by applying a static electric field over a solution of neutral molecules with dipolar chromophores. Implicitly, this description limits the applicability of this Electric-field-induced second-harmonic generation (EFISHG) technique ... 

Figure 3.2. Mechanistic description of TP absorption occurring from the ground state into a higher excited state (a) and to the lowest excited state (b). Mechanism (a) is representative for centrosymmetric compounds, while mechanism (b) is often discussed for dipolar chromophores with donor (D)-acceptor (A) pattern.

Thus, chromophores with large extinction coefficient are favored materials for TPA if the dipolar substitution pattern results in a large A/rol as well. Because the amplitude of both transitions is tuned by the same parameters, that is, Afoi and A/i01, dipolar chromophores can have the same excitation energy for both OP and TP excitation. 

Source Used for Determination of TPA Data for a Series of Dipolar Chromophores with the General Structures Taken in Various Solvents Using Different Methods... 

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