Showing papers on "Hyperpolarizability published in 1989"
TL;DR: A series of organic salts, in which the cation has been designed to have a large molecular hyperpolarizability, has been prepared as discussed by the authors, which leads to materials with large powder second harmonic generation efficiencies, the highest of which is roughly 1000 times that of a urea reference.
Abstract: A series of organic salts, in which the cation has been designed to have a large molecular hyperpolarizability, has been prepared. Variation of the counterion (anion) in many cases leads to materials with large powder second harmonic generation efficiencies, the highest of which is roughly 1000 times that of a urea reference.
620 citations
TL;DR: The measured halide ion hyperpolarizabilities for several alkali-halide crystals are in reasonable agreement with recent self-consistent calculations.
Abstract: The nonlinear refractive indices (${n}_{2}$) of a large number of optical crystals have been measured at a wavelength near one micrometer with use of nearly degenerate three-wave mixing. The measurements are compared with the predictions of an empirical formula derived by Boling, Glass, and Owyoung. This formula, which relates ${n}_{2}$ to the linear refractive index and its dispersion, is shown to be accurate to within about 30% for materials with nonlinear indices ranging over 3 orders of magnitude. Measurements for a number of binary oxide and fluoride crystals have been analyzed under the assumption that the hyperpolarizability of the anion is much larger than that of the cation. It is found that the hyperpolarizability of oxygen varies by a factor of 10, and that of fluorine varies by a factor of 7, depending on the size of the coordinating cation. This behavior is similar to that of the linear polarizability, although the hyperpolarizability is much more sensitive than the linear polarizability to the identity of the cation. The measured halide ion hyperpolarizabilities for several alkali-halide crystals are in reasonable agreement with recent self-consistent calculations. A semiempirical model was proposed by Wilson and Curtis to account for the dependence of the linear anionic polarizability on the radius of the cation. This model also accounts quite well for the variation of the hyperpolarizability of both fluorine and oxygen, except for cation partners that have filled or unfilled d-electron shells. The nonlinear indices of a number of complex oxides (i.e., those with more than one cation) have been calculated from the partial hyperpolarizabilities deduced from the data for the binary oxides. The calculated and measured values of ${n}_{2}$ agree to within an average error of 13%.
559 citations
TL;DR: In this article, the physicochemical properties of the isolated molecular units (symmetry, polarity, redox potentials, absorption spectrum) are deduced from their physicochemical characteristics.
Abstract: Molecular materials are made from molecular units, separately synthesized and subsequently organized into some condensed phases. Because of their very nature, the electrical properties (ferro- and antifemlectricity, semiconductivity) and the optical properties (polarizability and hyperpolarizability) of the molecular materials may be deduced from the physicochemical characteristics of the isolated molecular units (symmetry, polarity, redox potentials, absorption spectrum). Octaalkyl-phthalocyanine derivatives lead to columnar and nematic lenticular mesophases. These liquid crystalline phases are shown to be usable in the domains of electronics, opto-electronics and iono-electronics.
171 citations
TL;DR: The measurements of the third-order polarizability (gamma) of several platinum poly-ynes obtained using picosecond laser pulses showed low absorption in the visible and the near-infrared wavelengths.
Abstract: We present the measurements of the third-order polarizability (γ) of several platinum poly-ynes obtained using picosecond laser pulses. The real part of γ was measured using the optical Kerr effect with a 1.064-μm pump and a 0.532-μm probe. The imaginary part was evaluated from the two-photon absorption coefficient determined at 0.532 μm. The platinum poly-ynes had low absorption in the visible and the near-infrared wavelengths.
103 citations
TL;DR: In this paper, an ab initio calculation of polarizability and second hyperpolarizability for the benzene molecule including electron-electron correlation was performed using the finite field method.
Abstract: We present an ab initio calculation of polarizability and second hyperpolarizability for the benzene molecule including electron–electron correlation. The finite field method is used. For each selected strength of the applied electric field the energy of the benzene molecule is calculated using the self‐consistent field method (SCF) as well as with its Mo/ller–Plesset correction in the second order (MP‐2). Then the microscopic optical nonlinear responses are calculated by fitting both the SCF energy and the MP‐2 energy to a polynomial in the field strength. We find that electron correlation significantly enhances the second hyperpolarizability. For the polarizability, our computed value shows an excellent agreement with the experimentally measured value. For the second hyperpolarizability, the computed value using MP‐2 energy shows a reasonable agreement with that reported by the electrical field induced second harmonic (EFISH) generation but a poor agreement with the result of degenerate four wave mixing...
87 citations
TL;DR: The second hyperpolarizability of a conjugated polythiophene derivative, containing aromatic and quinoid moieties, was measured to be 1.2×10−31 esu as discussed by the authors.
Abstract: The second hyperpolarizability 〈γxxxx 〉 of a new, soluble, conjugated polythiophene derivative, containing aromatic and quinoid moieties, is measured to be 1.2×10−31 esu. The measurement was made at 532 nm in a dichloromethane solution by picosecond‐resolved degenerate four wave mixing. The corresponding macroscopic third‐order susceptibility χ(3 ) is estimated to be 4.6×10−9 esu, which is larger than that of the parent poly(2,5‐thiophene) and many currently known nonlinear optical polymers.
77 citations
TL;DR: In this article, electron-correlated wave functions have been used to determine the dynamic hyperpolarizability tensor (γ) and the dynamic field gradient polarizabilities (B and C) for helium.
Abstract: Accurate and explicitly electron‐correlated wave functions have been used to determine the dynamic hyperpolarizability tensor (γ) and the dynamic field‐gradient polarizabilities (B and C) for helium. The γ‐tensor is related to nonlinear optical processes such as the Kerr effect, second‐ and third‐harmonic generation and degenerate‐four‐wave mixing. In the static limit our results agree completely with a previous highly accurate variational‐perturbation treatment. For second‐harmonic generation at λ=4880 A the ratio γzzzz/γxxzz is 2.950, which may be compared with the experimental value of 2.949.
67 citations
TL;DR: In this paper, a nonlinear optical organic material, (-)2-(α-methylbenzylamino)-5-nitropyridine (MBANP), has been comprehensively investigated with the objective of application to frequency doubling of laser diodes.
Abstract: A nonlinear optical organic material, (-)2-(α-methylbenzylamino)-5-nitropyridine (MBANP), has been comprehensively investigated with the objective of application to frequency doubling of laser diodes. Its molecular hyperpolarizability is as large as that of p-nitroaniline. MBANP crystallizes with a highly asymmetric molecular arrangement. The largest nonlinear optical coefficient, d22, is measured to be 60 pm/V. The corresponding figure of merit for frequency doubling at 1.064 µm is 3.5 times larger than that for d33 of LiNbO3. Cerenkov-radiation-type, phase-matched second-harmonic generation has been demonstrated utilizing the d22 coefficient by making use of an appropriate waveguiding structure.
64 citations
TL;DR: In this article, the coupled-cluster doubles (CCD) model was used to calculate the dipole-dipole-quadrupole (B) and second dipole (γ) hyperpolarizabilities of the neon atom using a large basis set.
63 citations
TL;DR: In this article, the static dipole polarizability, second hyperpolarizability and dipole-dipole-quadrupole-four-rupole (DQ-4)-hyperpolarization for the Ne atom were computed using large Gaussian basis sets and coupled cluster wavefunctions.
55 citations
TL;DR: In this paper, the static longitudinal polarizability and hyperpolarizability for polydiacetylene (PDA) and polybutatriene (PBT) oligomers through C 26 are carried out using STO-3G and 4-31G bases.
TL;DR: The change in sign of beta and the observation that beta(0), a frequency-independent measure of hyperpolarizability, is the same at both frequencies demonstrate the validity of the two-state model of the second-order hyperp polarizability.
Abstract: We have demonstrated anomalous-dispersion phase-matched second-harmonic generation, using electric-field-induced second-harmonic generation in a liquid solution of Foron Brilliant Blue S-R (FBB). This dye has a sharp absorption maximum near 620 nm and a deep absorption minimum near 450 nm. The microscopic hyperpolarizability (β) of FBB was measured at 1.58 and 0.954 μm and was found to be 163 × 10−30 and −118 × 10−30 cm5/esu, respectively. The change in sign of β and the observation that β0, a frequency-independent measure of hyperpolarizability, is the same at both frequencies demonstrate the validity of the two-state model of the second-order hyperpolarizability.
TL;DR: In this article, Hartree-Fock calculations of the nonlinear optical properties of other atoms and molecules were used to show that the hyperpolarizability of the Ne atom decreases with increasing frequency at infrared frequencies.
Abstract: Measurements of electric-field--induced second-harmonic generation are presented which show that the hyperpolarizability (\ensuremath{\gamma}) of the Ne atom decreases with increasing frequency at infrared frequencies. Such negative dispersion of \ensuremath{\gamma} at frequencies far below the first resonance is unprecedented. The new data, when combined with the results of ab initio calculations indicate that the electron-correlation contribution is 40% of ${\ensuremath{\gamma}}_{\mathrm{Ne}}$. This raises the question of the adequacy of Hartree-Fock calculations of the nonlinear optical properties of other atoms and molecules.
TL;DR: In this paper, the scalar components of the second-order hyperpolarizability tensors appropriate to d.c.-field-induced second-harmonic generation (DC-SHG) at 1.064 and 1.9 nm were calculated for benzene, aniline, nitrobenzene and p-nitroaniline.
Abstract: The CNDO/VS sum-over-states (SOS) method has been used to calculate the scalar components of the second-order hyperpolarizability tensors appropriate to d.c.-field-induced second-harmonic generation (DC-SHG) at 1.064 nm and third-harmonic generation (THG) at 1.064 and 1.9 nm. The molecules considered are benzene, aniline, nitrobenzene and p-nitroaniline (PNA).The above calculations have been carried out using both the singly excited configuration interaction (SCI), and the singly and doubly excited configuration interaction (SDCI) models. Their suitability for evaluating third-order effects has been assessed, by extensively testing the convergence of the perturbation sum for the above molecules, although it must be noted that the results obtained are only semiquantitative. Furthermore, the importance of the charge-transfer state of PNA has also been assessed and the frequency dependence of its contribution investigated.
TL;DR: In this article, the magnetic hyperpolarizability η was calculated at the near-Hartree-Fock level for Li+, He and H2, and the connections between η and B hyperPolarizabilities were derived.
Abstract: The magnetic hyperpolarizability η is calculated at the near-Hartree-Fock level for Li+, He and H2. Connections between η and B hyperpolarizabilities are derived. For H2 values of Δη = 9·76 and 10·31 a.u. (0·26 and 0·28 × 10-42 (4πϵ0) cm3 G-2, respectively) are found in different basis sets. Zero-point averaging adds an estimated 1·7 a.u. to the equilibrium value for the H2 isotopomer, and field-induced changes in vibration a further 0·2 a.u., to give a total ab initio result that is 78 per cent of the value deduced from the most recent experimental measurement of the Cotton-Mouton constant.
TL;DR: In this paper, the derivatives of molecular dipole moments and polarizabilities with respect to nuclear coordinates are derived in terms of nonlocal polarizability densities, linear and nonlinear.
Abstract: New equations for the derivatives of molecular dipole moments and polarizabilities with respect to nuclear coordinates are derived in terms of nonlocal polarizability densities, linear and nonlinear. New equations are also derived for the electric field shielding tensors at nuclei of molecules in static external fields of arbitrary spatial variation. Both involve integrals of the dipole propagator and the polarizability densities. This analysis explains the relationship between the linear electric field shielding tensors and the infrared intensity for a vibrational mode; it also accounts for the relationship between the quadratic electric field shielding tensors and the Raman intensity, as well as relations connecting higher‐order shielding tensors to hyper‐Raman intensities. When a nucleus moves infinitesimally, the electronic charge distribution responds via its nonlocal polarizability density to the change in the Coulomb field due to that nucleus, and this produces the change in the electronic dipole moment. All of the quantum mechanical effects are contained within the polarizability density. Analogously, the change in the Coulomb field and response via the hyperpolarizability densities determine the change in electronic polarizability when a nuclear position shifts.
TL;DR: In this article, accurate and explicitly electron-correlated wave functions have been used to calculate the dipole polarizability of the helium isoelectronic series He,...,Ne8+.
Abstract: Accurate and explicitly electron‐correlated wave functions have been used to calculate the dipole polarizability (α), second hyperpolarizability (γ), dipole–dipole–quadrupole (B), and quadrupole–quadrupole (C) polarizabilities of the helium isoelectronic series He,...,Ne8+. It is believed that our results, which in nearly all cases are new, are very accurate and should serve as a benchmark for future experiments and calculations.
Patent•
30 Jun 1989TL;DR: Polyurethanes prepared from non-linear optical active diols (NLO-diols) of the formula according to claim 1, of which the essence is that they have a delocalized π electron system to which both an electron donor group and an electron acceptor group are coupled directly.
Abstract: Polyurethanes prepared from non-linear optical active diols (NLO-diols) of the formula according to claim 1, of which the essence is that they have a delocalized π electron system to which both an electron donor group and an electron acceptor group are coupled directly (DπA system) The polyurethanes have high hyperpolarizability densities and other favourable properties and can be easily prepared They are to be used in optical waveguides
TL;DR: In this paper, a simple model of coupled locally anharmonic oscillators which can be used to describe the optical nonlinearities in conjugated organic monomeric, oligomeric and polymeric structures is presented.
Abstract: We present a simple model of coupled locally anharmonic oscillators which can be used to describe the optical nonlinearities in conjugated organic monomeric, oligoneric, and polymeric structures. We show that the method can very readily be used to explain the dependence of the band gap, the polarizability α, and the second hyperpolarizability γ on the number of repeat units of conjugated chain compounds by adjusting two parameters: the local anharmonicity term and the oscillator coupling constant. To illustrate the usefulness of this model, we have calculated the dependence of the band gap, the polarizability α, and the second hyperpolarizability γ, as the function of the number of repeat units for the oligomers of thiophene and benzene. The results predicted by the coupled anharmonic oscillator model are in good agreement with those of the experimental studies on thiophene and benzene oligomers recently reported by our group. In addition, the predicted power dependences of orientationally averaged 〈α〉 an...
TL;DR: The quadratic hyperpolarizability tensor of 4-amino−4'−nitrodiphenyl sulfide has been sampled by measurement of the z component of its vector part, when z is the permanent dipole direction.
Abstract: The quadratic hyperpolarizability tensor of 4‐amino‐4’‐nitrodiphenyl sulfide has been sampled by measurement of the z component of its vector part, when z is the permanent dipole direction. This was also accomplished for the oxygen, selenium, and tellurium analogues. It was found that large differences in their frequency‐doubling efficiency as powdered solids are not reflected in this molecular property. The sulfur, selenium and tellurium ethers have about the same hyperpolarizabilities while that of the oxygen member is somewhat lower.
TL;DR: In this article, it was shown that the electronic charge distribution responds to the change in Coulomb field due to the nucleus via the same hyperpolarizability density that describes its response to external fields.
Abstract: The nonlocal polarizability density α(r;r’,ω) is a linear‐response tensor that determines the electronic polarization induced at point r in a molecule, by an external electric field of frequency ω, acting at r’. This work focuses on the change in α(r;r’,ω) when a nuclear position shifts infinitesimally. We prove directly that the electronic charge distribution responds to the change in Coulomb field due to the nucleus via the same hyperpolarizability density that describes its response to external fields. This generalizes a result found previously for the static (ω=0) polarizability density. The work also provides a new interpretation for the integrated intensities of vibrational Raman bands: it proves that the intensities depend on the hyperpolarizability densities and the dipole propagator.
TL;DR: In this paper, a hybrid model is used to calculate the dipole moments of care gas dimers and trimers and the exchange and polarization interactions are obtained with a single-configuration self-consistent field (SCF) calculation and the dispersion contribution to the dipoles is obtained by perturbation theory.
Patent•
29 Jun 1989TL;DR: In this paper, the polyurethanes are obtained from nonlinear optical active diols (NLO-diols) of a certain general formula, which have a delocalized π electron system to which both an electron donor group and an electron acceptor group are coupled directly (DπA system).
Abstract: Polyurethanes having high hyperpolarizability densities and other favorable properties can be easily prepared from nonlinear optical active diols (NLO-diols) of a certain general formula, which have a delocalized π electron system to which both an electron donor group and an electron acceptor group are coupled directly (DπA system). The polyurethanes may be used in optical waveguides.
TL;DR: In this paper, the diamagnetic part of the Cotton-Mouton constant and the hyperpolarizability of helium are obtained within the coupled Hartree-Fock approximation; they involve solutions of integro-differential equations which are solved numerically in a calculation of these properties.
TL;DR: In this paper, a systematic study of the dependence of the band gap, the linear optical susceptibility, the polarizability α, and the second hyperpolarizability γ, on the number of repeat unit is conducted for the thiophene series from monomer to hexamer.
Abstract: A systematic study of the dependence of the band gap, the linear optical susceptibility, the polarizability α, and the second hyperpolarizability γ, on the number of repeat unit is conducted for the thiophene series from monomer to hexamer. The linear optical susceptibilities for oligomers have been determined from the refractive index measurements on vacuum deposited films using the m lines technique. The orientationally averaged polarizabilities 〈α〉 have been measured from refractive index measurements of THF solutions. The orientationally averaged second hyperpolarizabilities 〈γ〉 have been measured by degenerate four‐wave mixing studies of THF solutions. The validity of the Lorentz–Lorenz approximation is tested and found to be satisfactory. The experimental values of 〈α〉 and 〈γ〉 for thiophene and 〈α〉 for bithiophene are found to be in qualitative agreement with those obtained by a recent ab initio calculation which used the finite field method and included diffuse polarization functions. The experimentally observed dependence of 〈α〉 and 〈γ〉 on the number N of the thiophene repeat unit is compared with that predicted by a free electron model, PPP methods, and the ab initio calculations. For the case of polarizability, the repeat unit dependence is in good agreement with that predicted by the ab initio calculations but for the case of second hyperpolarizability, the agreement is not as good.
Patent•
10 Oct 1989TL;DR: In this article, the second hyperpolarizability of conjugated organic polymers has been improved by adding defects in the polymer chain, such as light doping, electron donating or accepting groups, and photoexcitable species.
Abstract: Highly conjugated organic polymers typically have large non-resonant electronic susceptibilities, which give the molecules unusual optical properties. To enhance these properties, "defects" are introduced into the polymer chain. Examples include light doping of the conjugated polymer and synthesis, conjugated polymers which incorporate either electron donating or accepting groups, and conjugated polymers which contains a photoexcitable species capable of reversibly transferring its electron to an acceptor. Such defects in the chain permit enhancement of the second hyperpolarizability by at least an order of magnitude.
TL;DR: In this paper, the authors presented experimental and theoretical results on the intensity of forbidden IR and Raman bands of CS 2 in liquid solutions, and evaluated the different electrical contributions to the intensities and deduced that β′ for CS 2 is about ten times larger than in CO 2.
01 Jan 1989
TL;DR: In this paper, the dependence of the second molecular hyperpolarizability (SMH) on the defect-state occupancy and energy in finite polyenes is calculated using a one-electron tight-binding model.
Abstract: The presence of conjugation and substitution defects introduces gap states in finite polyenes that are shown to influence the size and sign of the second molecular hyperpolarizability (SMH). Using a one-electron tight-binding model, the dependence of SMH on the defect-state occupancy and energy in finite polyenes is calculated. Defects can cause a significant decrease or enhancement of SMH by impeding charge delocalization or by creating partly filled bands (mimicking the one-band limit), respectively. Concomitant sign changes in SMH are predicted. Calculation results suggest strategies for designing molecules that can be either photochemically or electrochemically switched between states with considerably different SMHs.
TL;DR: In this paper, a study for finding compounds with higher transparencies for blue light resulted in 1- (4-nitrophenyl) azole derivatives and 5-nitrobenzazole derivatives.
Abstract: Nonlinear optical materials, which are expected in various applications such as optical information processing, telecommunication, integrated optics, etc., have aroused our interest. Among many organic nonlinear optical materials which are considered to have a number of merits compared with inorganic ones, 2-methyl-4-nitroaniline (MNA) is one of the most famous compounds. This compound, however, has an insufficient transparency in blue light region, making MNA inadequate for a frequency doubler for blue light generator.Our study for finding compounds with higher transparencies for blue light resulted in 1- (4-nitrophenyl) azole derivatives and 5-nitrobenzazole derivatives. When compared from the viewpoint of the second order molecular hyperpolarizability (β) calculated by PPP-CI method, the 1- (4-nitrophenyl) azole derivatives were judged better than 5-nitrobenzazole derivatives.