Optimization of the molecular hyperpolarizability for second harmonic generation in chiral media

Ostroverkhov, Victor; Ostroverkhova, Oksana; Petschek, Rolfe G.; Singer, Kenneth D.; Сухомлинова, Л. И.; Twieg, Robert J.; Wang, S.-X.; Chien, Liang–Chy

doi:10.1016/s0301-0104(00)00149-x

Cited by 37 publications

(29 citation statements)

References 32 publications

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“…perpendicular to the contact line) is consistent with that observed for DNA solutions dried in air at lower concentrations. [26] It has been demonstrated both theoretically [27][28][29][30][31] and experimentally [32,33] that chirality within the chromophores is not a requirement for chiral-specific SHG activity, provided that the achiral chromophores can be arranged with asymmetry in the twist angle y (Figure 1). The unique anti-parallel structure of DNA combined with the spontaneous assembly of aligned materials suggests that DNA can potentially template chiral macroscopic assembly of NLO-active chromophores without requiring additional external forces.…”

Section: Resultsmentioning

confidence: 99%

DNA‐Based Polymers as Chiral Templates for Second‐Order Nonlinear Optical Materials

et al. 2009

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The unique symmetry properties of chiral systems allow the emergence of coherent second harmonic generation in polymeric materials lacking polar order. Deoxyribonucleic acid (DNA) treated with the surfactant cetyltrimethylammonium (CTMA) was drop-cast to spontaneously form films that are active for coherent second harmonic generation (SHG). SHG images acquired as a function of incident and exigent polarization are in good agreement with theoretical predictions assuming nonpolar D(infinity) symmetry for the double-stranded DNA chains. Doping the DNA films with crystal violet substantially increases the efficiency of SHG, but does not significantly alter the polarization-dependence, suggesting that the SHG generated upon doping arises from the same chiral-specific origin, presumably templated by the DNA. These results raise the possibility of new design strategies for organic nonlinear optical materials based on soft chiral polymers that do not require polar order.

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Section: Resultsmentioning

confidence: 99%

DNA‐Based Polymers as Chiral Templates for Second‐Order Nonlinear Optical Materials

et al. 2009

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“…A free-energy cost is usually paid upon the imposition of polar order. [44] By nature of this inherent instability, high degrees of polar order are generally difficult to achieve, and the nonlinear optical efficiency of poled polymer films is often reduced over time through orientational relaxation within the matrix. [110] The unique symmetry properties of chiral media overcome many of these limitations, and materials with enhanced stability in their nonlinear optical properties can be envisioned (Figure 6).…”

Section: Chiral Materials For Nonlinear Opticsmentioning

confidence: 99%

Molecular Origins of the Remarkable Chiral Sensitivity of Second‐Order Nonlinear Optics

2004

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Recent observations of remarkably large chiroptical effects in second-harmonic generation (SHG) and sum-frequency generation (SFG) measurements suggest exciting possibilities for the development of new chiral-specific spectroscopies and novel chiral materials for nonlinear optics. Several fundamental studies designed to elucidate the molecular and macromolecular origins of the chiral responses are reviewed to provide a framework for development of this emerging field. In general, the chiral activity in SHG and SFG has the potential to arise from complex interactions between hosts of different competing effects. Fortunately, relatively simple electric dipole-allowed mechanisms routinely dominate the nonlinear optical chiral activities of most practical systemsexpressions can often be generated to link the. This substantial reduction in complexity allows for the development of simple models connecting the macroscopic nonlinear optical response to intuitive molecular and supramolecular properties.

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“…(6) in many cases, provided that the states with the correct symmetries are included in the sum. 6 For understanding the low-lying ele ctronic states, Λ-shaped molecules that have a single conjugated region consisting of an apex and two identical "feet" can o ften be treated as having C 2v or C 2 symmetry. The electronic states of these molecules can be either symmetric ( A-type) or antisymmetric ( B-type) functions with respect to the 180° rotation.…”

Section: 2mentioning

confidence: 99%

“…(6), only the B-states will contribute to ( ) 2 ijk b and, in fact, have optimal g eometry since the B-state transition moment is orthogonal to the symmetry axis. 6,14 To maximize the nonlinear optical r esponse in chiral media composed of any Λ-shaped molecules, the lowest-lying state should have substantial B-character. Semiempirical calculations for several Λ-shaped molecules indicate that some molecules of this type indeed do have quite strongly absorbing low-lying states with the appropriate symmetry.…”

Section: 2mentioning

confidence: 99%

“…4,5 We have recently described a scheme to optimize molecular properties of multidimensional NLO chromophores for use in chiral nonlinear materials using molecular engineering, and including sum-over-states quantum-mechanical calculations and measurements of the rotational invariants of molecular hyperpolarizability b by means of Kleinman-disallowed hyper-Rayleigh scattering. 6 Alternative nonpolar methods of alignment exploit the tensorial nature of the molecular hyperpolarizability b. Generally, the second harmonic hyperpolarizability tensor can be decomposed into four components, two of which transform under three-dimensional rotations as traceless symmetric second-and third-rank tensors.…”

Section: Introductionmentioning

confidence: 99%

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Optimization of the nonlinear optical response in chiral media

et al. 2001

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This paper describes the development and optimization of chiral, non-polar media with large second-order nonlinear optical responses. We employ molecular engineering, quantum-mechanical sum-over-states theory, and measurements of molecular hyperpolarizability by means of Kleinman-disallowed hyper-Rayleigh scattering in order to understand molecular properties. Then we analyze the appropriate arrangement of the chromophores that produce an optimum axial nonlinear optical medium. Chromophores with large Kleinman disallowed traceless symmetric second rank tensor hyper-polarizabilities β can be aligned so as to result in large susceptibilities, χ (2) , in structures that lack polar order. We found that L-shaped chromophores with C 2v or similar symmetry are good candidates for these materials as they can exhibit large second-rank components of the hyperpolarizability tensor. A wide variety of techniques can be used to fabricate bulk materials belonging to the chiral non-polar symmetry groups, D ∞ and D 2 . The microscopic chromophore alignment schemes that optimize the NLO response in such materials are deduced from general symmetry consideration for both molecules and bulk.

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Optimization of the molecular hyperpolarizability for second harmonic generation in chiral media

Cited by 37 publications

References 32 publications

DNA‐Based Polymers as Chiral Templates for Second‐Order Nonlinear Optical Materials

DNA‐Based Polymers as Chiral Templates for Second‐Order Nonlinear Optical Materials

Molecular Origins of the Remarkable Chiral Sensitivity of Second‐Order Nonlinear Optics

Optimization of the nonlinear optical response in chiral media

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