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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TL;DR: This work has found that both the frequencies and intensities of the strongest Raman lines (R mode) are strongly influenced by intermolecular interactions, and proposes a very simple mathematical model for the prediction of the Raman frequencies of interacting systems.
Abstract: In this work, we analyze the effect of intermolecular dipole-dipole interactions on Raman spectra of polyconjugated molecules. In particular, the behavior of push-pull polyenes has been studied. By means of density functional theory (DFT) calculations on isolated molecules and dimers, we have found that both the frequencies and intensities of the strongest Raman lines (R mode) are strongly influenced by intermolecular interactions. The results have been rationalized within the effective conjugation coordinate (ECC) theory developed in the past. The calculations for different configurations have also shown that the Raman spectra are sensible to different intermolecular geometries, thus implying a possible application of vibrational spectroscopy to the study of supramolecular properties of polyconjugated systems. The comparison with the available experimental spectra confirms the results obtained with the DFT computations. Finally, a very simple mathematical model is proposed for the prediction of the Raman frequencies of interacting systems. From the knowledge of just a few quantities for the isolated molecule and of some geometrical parameters, an estimate of the frequency of the dimers can be obtained. Despite its simplicity, this model gives results in very good agreement with DFT calculations carried out explicitly on dimers in several different arrangements.
8 citations
TL;DR: In this paper, triplet quenching is a limiting factor in the SLM performance and better results in terms of writing intensity and contrast ratio are obtained in transient waveguide switch configuration.
Abstract: Nonlinear triplet-triplet absorption in organic molecules can be used to construct all-optical switches and spatial light modulators (SLMs). SLM experiments were performed on eosin/PVA films using Ar laser light for writing and He-Ne laser for reading. The results indicate that triplet quenching is a limiting factor in the SLM performance. Better results in terms of writing intensity and contrast ratio are obtained in transient waveguide switch configuration.
8 citations
TL;DR: In this paper, the habit of the organic non-linear optical material meta-nitroaniline (mNA) crystallized from different organic solvents such as acetone, benzene, ethyl acetate, n-hexane, methanol and toluene were studied.
Abstract: The habit of the organic non-linear optical material meta-nitroaniline (mNA) crystallized from different organic solvents such as acetone, benzene, ethyl acetate, n-hexane, methanol and toluene were studied. Solubility of mNA in these solvents at various temperatures in the range between 288 and 323 K was determined by gravimetric method. Crystals were grown by restricted evaporation of solvents method. Solutions with different solvents having different chemical nature and polarity yielded crystals with different habits: one-dimensional needles, two-dimensional rhombic platelets and three-dimensional octahedral. In addition, the mNA crystals show unidirectional growth behaviour along its polar [001] direction irrespective of the solvents used. All the grown crystals were found to be orthorhombic system with point group mm2 and space group Pbc21 which was confirmed by powder X-ray diffraction study. Optical transmittance study showed that the grown mNA single crystals have optical transparency in the wavelength range between 430 and 1550 nm. SHG efficiency of the grown mNA crystal was 3 times grater than KDP. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
8 citations
TL;DR: X-ray diffraction analysis of 3-methyl-4-styrylpyridine methiodide crystal showed that this compound was packed in a non-centrosymmetric way about 50 degrees with respect to the crystal polar axis as mentioned in this paper.
8 citations
TL;DR: Centrosymmetric furan-containing cyclophandienes 3 and 4, synthesized by the furan annulation protocol, have been shown to exhibit extraordinarily large Stokes shifts and second-order nonlinear optical beta values.
Abstract: Centrosymmetric furan-containing cyclophandienes 3 and 4, synthesized by our furan annulation protocol, have been shown to exhibit extraordinarily large Stokes shifts and second-order nonlinear optical beta values. The beta values for 3 and 4 measured at 1.32 mum are 208 and 530x10(-30) esu, respectively. The beta values of 3 and 4 are similar to those of respective cyclophenes 1 a and 7 in which strong hyperpoarizable interactions between two twisted pi-systems (oligoaryl and bridging double bond) might take place. Symmetry breaking due to the resonance contribution (cf. 2) and the unique structural features of 3 and 4 has been used to account for this unusual photophysical behavior.
8 citations
Cites background from "Nonlinear optical properties of org..."
...Lack of a center of symmetry in a molecule or a bulk material is a general criterion to exhibit second-order nonlinear optical (NLO) properties.([6]) However, molecular materials with a centrosymmetric structure can be NLO active in the solid state when a magnetic dipole([7]) or an electric quadrupole([8]) is present....
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