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MonographDOI

Nonlinear optical properties of organic and polymeric materials

29 Sep 1983-
About: The article was published on 1983-09-29 and is currently open access. It has received 762 citations till now.
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Journal ArticleDOI
TL;DR: In this paper, ultrasonic, piezoelectric and thermal expansivity measurements have been carried out using single-crystal samples of 3-nitroaniline (mNA).
Abstract: Ultrasonic, piezoelectric and thermal expansivity measurements have been carried out using single-crystal samples of 3-nitroaniline (meta-nitroaniline mNA). Longitudinal and transverse velocity measurements in six crystal directions were used to determine the nine elastic coefficients. These data are discussed in relation to the intermolecular interactions existing within the crystal structure of mNA. Piezoelectric measurements show that this organic material exhibits coefficients which are of similar magnitude to those observed for inorganic materials such as lithium niobate.

18 citations

Journal ArticleDOI
TL;DR: In this article, a new experimental method for observing chromophore relaxation dynamics in nonlinear optical polymer systems is described, which is similar to dielectric relaxation measurements, which probe the linear susceptibility χ(1), but this new method is chromophoresensitive and probes the nonlinear susceptibility φ(2) in the frequency domain, monitoring second-harmonic generation during the application of a strong ac electric field.
Abstract: A new experimental method for observing chromophore relaxation dynamics in nonlinear optical polymer systems is described. The method is similar to dielectric relaxation measurements, which probe the linear susceptibility χ(1), but this new method is chromophore selective and probes the nonlinear susceptibility χ(2) in the frequency domain, monitoring second-harmonic generation during the application of a strong ac electric field. The out-of-phase component of χ(2) exhibits behavior similar to that of the loss component in dielectric relaxation and is shown to be unaffected by electric-field-induced third-order effects. The relation to dielectric relaxation is discussed, and stretched exponential parameters are extracted for a Disperse-Red-1/poly(methyl methacrylate) guest–host system.

18 citations

Journal ArticleDOI
TL;DR: In this paper, a hierarchy of point groups in connection with nonlinear efficiency can be established, which helps define the optimum molecular packing for each crystal point group, such as those based on chirality, cancellation or dipole-dipole interaction forces and hydrogen bonding are defined and exemplified in specific cases.
Abstract: The remarkably high quadratic optically nonlinear efficiency of some organic molecular crystals can be ascribed to properly “tailored” structural features at both molecular and crystalline levels. Introduced within the framework of an oriented gas model, symmetry considerations play a foremost part, as detailed in the case of a monoclinic P21 crystal composed of planar molecular units, and lead to experimentally confirmed structural relations between macroscopic susceptibility coefficients. A hierarchy of point groups in connection with nonlinear efficiency can be established. This helps define the optimum molecular packing for each crystal point group. Different engineering strategies, such as those based on chirality, cancellation or dipole-dipole interaction forces and hydrogen bonding are defined and exemplified in specific cases. Except in the case of chiral molecular units, it is impossible to infer the crystalline symmetry type. Statistical correlations between molecular and crystalline sy...

18 citations

Journal ArticleDOI
TL;DR: In this paper, a series of soft salts of stoichiometry (Cn-AI-), where A and C represent redox-active cluster cations and anions have been prepared, have been studied with a long term view of obtaining examples in which the charge x is non-integral.
Abstract: A series of salts of stoichiometry (Cn-)(AI-), where A and C represent redox-active cluster cations and anions have been prepared. These compounds which we call "soft salts", have been studied with a long term view of obtaining examples in which the charge x is non-integral. The synthesis and bulk properties of new organometallic intercalation compounds such as (Moo,( Fe,(q-C,HS),(p-S),),, Is) are reported. Finally, the synthesis of organometallic compounds with large non-linear optical properties will be described. The compound ((cis)-( l-ferrocenyl-2-(4-nitrophenyl)ethylene) ) has been shown to have the ability for second harmonic generation (S.H.G.) which is 62 times that of urea.

18 citations

Journal ArticleDOI
TL;DR: In this article, a πelectron method which allows for the systematic inclusion of configuration interaction of any order has been developed for the computation of electronic and optical properties of conjugated molecules.
Abstract: A π‐electron method which allows for the systematic inclusion of configuration interaction of any order has been developed for the computation of electronic and optical properties of conjugated molecules. It has been used to study the effect of electron correlation on these properties in all trans finite polyenes of up to 16 carbon atoms. For smaller molecules it has been possible to carry out a complete set of CI calculations, from singly excited (SCI) to full configuration interaction (FCI). For the larger molecules the SCI and doubly excited CI (SDCI) calculations have been performed. The program permits the execution of a configuration interaction calculation of any order, n, in which all configurations involving the excitation of 1,2,...,n electrons from the occupied π‐orbitals of the Hartree–Fock ground‐state to the virtual π‐orbitals are included. The set of π‐orbitals is extracted from the ground state obtained from an all valence‐electron, complete neglect of differential overlap (CNDO) calculation. The configurations are represented by binary integers so that their generation and storage is very rapid and efficient. The nonlinear optical properties have been computed mainly by the correction vector method but in some cases the sum‐over‐states (SOS) method has also been used to study the evolution of the THG coefficient as virtual states of increasing energy are added. The results obtained for the finite polyenes are found to be in very good agreement with both experimental and other theoretical values in literature. The results clearly show the effect of electron correlation, which is found to affect the electronic and optical properties of these systems both qualitatively and quantitatively.

18 citations