Showing papers on "Hyperpolarizability published in 1996"
TL;DR: In this article, the theoretical basis for the exceptionally large molecular first hyperpolarizabilities inherent to (5,15-diethynylporphinato) metal-bridged donor-acceptor (D−A) molecules was described.
Abstract: We describe the theoretical basis for the exceptionally large molecular first hyperpolarizabilities inherent to (5,15-diethynylporphinato)metal-bridged donor−acceptor (D−A) molecules. β values relevant for hyper-Rayleigh experiments are calculated at 1.064 and 0.830 μm for a complex with such a structure, [5-((4‘-(dimethylamino)phenyl)ethynyl)-15-((4‘‘-nitrophenyl)ethynyl)-10,20-diphenylporphinato]zinc(II), and are 472 × 10-30 and 8152 × 10-30 cm5/esu, respectively. The values are 1 order of magnitude larger than that calculated for any other porphyrin bridged donor−acceptor chromophore studied to date. The considerably enhanced hyperpolarizability arises from the significant excited-state electronic asymmetry manifest in such structures (derived from the strong bridge-mediated D−A coupling enabled by the largely porphyrin-based excited state) and the large bridge-centered oscillator strength in this new class of D−bridge−A molecules. Our analysis of NLO properties (based upon INDO/SCI calculations within...
222 citations
TL;DR: In this paper, a conjugated donor-acceptor chromophore was applied to polycarbonate at 20 percent weight loading to obtain a polymer film with an electro-optic coefficient, r_(33), of 55 picometers per volt at 1.313 micrometers.
Abstract: Syntheses of a series of conjugated donor-acceptor chromophores, based on a strongly electron-withdrawing heterocyclic acceptor, have led to compounds with large second-order optical nonlinearities. Incorporation of one of these chromophores into polycarbonate at 20 percent weight loading yielded, after poling at 150 volts per micrometer, a polymer film with an electro-optic coefficient, r_(33), of 55 picometers per volt at 1.313 micrometers. This value is roughly twice that of lithium niobate. A variant of one of these chromophores exhibited improved thermal stability as needed for use in polymers with higher glass transition temperatures. The chromophore was soluble in common organic solvents, had a scalar product of the dipole moment, μ, and the molecular first hyperpolarizability, β (corrected for dispersion), of roughly 5000 × 10^(−48) electrostatic units, and showed less than 10 percent decomposition after heating for 20 minutes in air and at 200°C in an inert organic solvent.
193 citations
IBM1
TL;DR: A series of symmetric derivatives of 4-(dicyanomethylene)-2-methyl-6-(p-(dimethylamino)styryl)-4H-pyran (DCM laser dye) has been synthesized, and the nonlinear optical properties and thermal decomposition temperatures of each of the chromophores has been measured as discussed by the authors.
Abstract: A series of symmetric derivatives of 4-(dicyanomethylene)-2-methyl-6-(p-(dimethylamino)styryl)-4H-pyran (DCM laser dye) has been synthesized, and the nonlinear optical properties and thermal decomposition temperatures of each of the chromophores has been measured. The symmetric chromophores all have larger hyperpolarizabilities than one would expect based on their absorption maxima. Estimations of their oscillator strengths based upon UV/vis spectra are all well above 1.0. It is proposed that these compounds possess two excited electronic states close to each other in energy, both contributing to the hyperpolarizability in an additive fashion. Electro-optical absorption spectroscopy data and semiempirical calculations on a model compound support this hypothesis. The implications of these results with regard to the tradeoff between nonlinearity and transparency are discussed. The large dipole moments and high decomposition temperatures of these chromophores make them attractive candidates for use in electr...
174 citations
TL;DR: In this paper, a Schiff-base ligand based on condensation of diaminomaleonitrile and 4-(diethylamino)salicylaldehyde is reported with its copper, nickel, and zinc complexes.
Abstract: A new Schiff-base ligand based on the condensation of diaminomaleonitrile and 4-(diethylamino)salicylaldehyde is reported with its copper, nickel, and zinc complexes. Their second-order nonlinear optical properties are investigated by electric field induced second harmonic (EFISH) and ZINDO quantum-chemical calculations to probe the role of the metal center in the nonlinearity. All the complexes exhibit a second-order nonlinear response that is larger than that of the ligand with an hyperpolarizability (β) value of 400 (±100) 10-30 cm5 esu-1 for the zinc derivative at 1.34 μm. Theoretical calculations indicate that the two-level model is inadequate to describe the nonlinearity in such systems.
154 citations
TL;DR: In this article, the first hyperpolarizabilities of organic nonlinear optical chromophores were measured at incident wavelengths of 1064 and 1319 nm with approximately 5% to 10% uncertainty in the relative first hyper polarizability.
Abstract: Hyper‐Rayleigh light scattering measurements at incident wavelengths of 1064 and 1319 nm are reported for several organic nonlinear optical chromophores in solution with approximately 5%–10% uncertainty in the relative first hyperpolarizabilities. The measured chromophores include representatives from C1, Cs, C2V, and D3 molecular point groups and include both neutral and ionic compounds. The measurements were made with 2–5 cm−1 spectral resolution and include polarization analysis of the incident and scattered light. Polarization ratios were measured with 2%–3% uncertainty for each molecule, and relative magnitudes of the hyperpolarizability components were deduced. Two‐photon induced fluorescence from several chromophores was observed to overlap with the scattered second harmonic light spectrum. The use of a scanning monochromator, however, generally allows the separation of these two sources of photons. The measured first hyperpolarizabilities are consistent with previous electric field induced second ...
152 citations
TL;DR: In this paper, the effects of the valence and coordination number of Fe ions on the third-order nonlinear optical susceptibility, χ(3), have been examined for sol-gel derived α•Fe2O3, γ•Fe3, and Fe3O4 thin films, and it was considered that χ3 was enhanced by the pair excitation process involving the simultaneous excitation of magnetically coupled two neighboring Fe3+ ions as well as by virtual transition from O 2p orbitals to Fe 3d orbitals.
Abstract: The third‐order nonlinear optical properties of sol–gel derived α‐Fe2O3, γ‐Fe2O3, and Fe3O4 thin films have been investigated by the third‐harmonic generation method. Especially, the effects of the valence and coordination number of Fe ions on the third‐order nonlinear optical susceptibility, χ(3), have been examined. The χ(3) values of α‐Fe2O3, γ‐Fe2O3, and Fe3O4 thin films were 5.8×10−11, 2.1×10−11, and 4.0×10−10 esu, respectively, which are the highest values among inorganic oxides reported so far. It was considered that χ(3) of α‐Fe2O3 and γ‐Fe2O3 was enhanced by the pair excitation process involving the simultaneous excitation of magnetically coupled two neighboring Fe3+ ions as well as by virtual transition from O 2p orbitals to Fe 3d orbitals while χ(3) of Fe3O4 was enhanced by both one‐ and three‐photon resonances. The higher second hyperpolarizability, γ(Fex/yO), was obtained when Fe ions are 3+ rather than 2+ and octahedrally rather than tetrahedrally coordinated by oxygens.
129 citations
TL;DR: In this paper, it was shown that the second-order optical nonlinearity of an onedimensional, rod-shaped, dipolar molecule such as a donor-acceptor disubstituted benzenes, biphenyls, polyenes, stilbenes, and tolanes arises from the highly polarizable charge asymmetry of the n-conjugated system.
Abstract: The development of highly efficient organic nonlinear optical materials for opto-electronic applications, which are promising for high-speed information processing and telecommunications, has drawn considerable attention over the last decade."] Although various prototype optoelectronic devices have been successfully demonstrated, the improvement of practical devices still requires further materials and product device developments.[*] Opto-electronic components based on second-order nonlinear optical effects such as linear electro-optic, nonlinear optical, and photorefractive effects require materials with large second-order optical nonlinearities. The optimization of both the molecular hyperpolarizability /3 and the non-centrosymmetric molecular order in the bulk are essential prerequisites to the design of useful molecular or polymeric materials with large secondorder optical nonlinearitie~.[~] It has been theoretically and experimentally shown that the origin of large optical nonlinearities of a onedimensional, rod-shaped, dipolar molecule such as a donoracceptor disubstituted benzenes, biphenyls, polyenes, stilbenes, and tolanes arises from the highly polarizable charge asymmetry of the n-conjugated system."*31 Although over the last few yearsr4] there has been tremendous progress in the understanding and optimization of the first-order molecular hyperpolarizability of these classical dipolar chromophores, these highly hyperpolarizable chromophores, especially donor-acceptor disubstituted polyenes, are usually limited in practical applications because of their chemical instability. Furthermore, the formation of efficient acentric crystals, and the good orientational order and temporal stability in electrically poled polymers of classical dipolar chromophores, are in general challenging materials
120 citations
TL;DR: Time-resolved hyper-Rayleigh scattering experiments using a femtosecond mode-locked Ti-sapphire laser are presented in this paper, which is capable of discriminating between hyper-rayleigh scattered light and fluorescent emission induced by multiphoton absorption with a time resolution of 80 ps.
111 citations
TL;DR: In this article, an extensive ab initio study of the electric dipole polarizability and hyperpolarizability of carbon monoxide was performed, and the bond length dependence of the molecular properties has been determined.
Abstract: We report an extensive ab initio study of the electric dipole polarizability and hyperpolarizability of carbon monoxide. The bond length dependence of the molecular properties has been determined f...
108 citations
TL;DR: A number of thermally and optically stable bis-dipolar chiral molecules based on two geometries of the binaphthol (BN) system with different acceptors/substituents have been synthesized for the first time, and the synthetic routes are reported as discussed by the authors.
Abstract: A number of thermally and optically stable, bis-dipolar chiral molecules based on two geometries of the binaphthol (BN) system with different acceptors/substituents have been synthesized for the first time, and the synthetic routes are reported: optically pure 6,6‘-disubstituted 2,2‘-diethoxy-1,1‘-binaphthyls {R, R‘= −Br, −CHO, −CHC(CN)(COOEt), −CHC(CN)2, −CHCHCN, −CHCH(p-NO2Ph)} and optically pure 9,14-disubstituted dinaphtho[2,1-d:1‘,2‘-f][1,3]dioxepins {R, R‘ = −Br, −CHO, −CH=C(CN)(COOEt), −CHC(CN)2, −CHCHCN, −CHCHSO2CH3, −CHCHCHO, −CHCHCHC(CN)2}. All molecules possess two equal donor−acceptor systems linked together to give a bis-dipolar system. Two mono-dipolar 6-substituted 2-butoxynaphthalene (R = −CHC(CN)2, −CHC(CN)(COOEt)) donor−acceptor systems were prepared as references. The linear optical properties including solvatochromic shifts of absorption and fluorescence revealed strong charge transfer excitations in the new dipolar systems. The molecules show a high first hyperpolarizability β (up to...
107 citations
TL;DR: In this article, a model of a conjugated chain as a collection of almost planar segments, separated by large angular breaks was derived from a microscopic model which includes conjugation and steric interactions.
Abstract: A physical picture of a conjugated chain as a collection of almost planar segments, separated by large angular breaks arises from a microscopic model which includes conjugation and steric interactions. The conjugation part of the standard phenomenological Hamiltonian for torsional motion is also derived from the model. We obtain a probability distribution of the length of segments between those breaks as the relevant factor for the behavior of the chain. We also perform numerical simulations of the structure and properties of these chains; the results of this are in agreement with our analytic predictions. In explaining experimental data for optical properties, such as the second hyperpolarizability, γ, our theory provides improved agreement over previous models.
TL;DR: In this paper, the dipole moments of the NLO chromophores were shown to be in an antiparallel orientation similar to that in a pseudo-centrosymmetric structure, leading to a negative solvatochromic behavior.
Abstract: Organic nonlinear optical (NLO) materials, both single crystals and polymers, based on extended π-electron systems have been proposed for electro-optical applications, especially for fast electro-optical modulation, due to the large electronic contribution to the electro-optic effects and the low dielectric constant of organic materials.1 Two key parameters of optimal electro-optical organic materials are that they contain stable chromophoric molecules with large molecular hyperpolarizabilities and that these molecules are aligned with the vector part of the molecular hyperpolarizabilities parallel to each other in a non-centrosymmetric packing.2 Compared with polymer materials,3 organic crystals are of great interest since a reliable and a time independent orientation of NLO chromophores in the lattice can be imposed. Difficulties of organic crystals for practical second-order NLO applications are due to the fact that most of these chromophores (90% of the achiral organic molecules) crystallize centrosymmetrically, leading to a cancellation of the second-order NLO effects. In addition, most optimized NLO chromophores normally show poor crystallinity, which limits the growth of good quality crystals. In this work we report on a novel organic electro-optic crystal in which the dipole moments of the NLO chromophores (merocyanine,M2, and protonated merocyanine, [H-M2]+) are in an antiparallel orientation similar to that in a pseudo-centrosymmetric structure. However, based on a proton asymmetry, the vector parts of the first hyperpolarizabilities of NLO chromophores (M2 and [H-M2]+) are in a completely parallel orientation. This work also presents a successful example to improve the crystallinity of a highly hyperpolarizable chromophore. Our interest in the merocyanine dye, M, was motivated by the fact that M is one of the best NLO chromophores with a very large molecular first-order hyperpolarizability, âvec M ,4 and with very good photo and thermal stabilities. The merocyanine dye’s electronic structure depends on the relative contribution of its two resonance structures, a quinonoid form, Mq, and a zwitterionic form,Mz, which are very sensitive to a modification of its dielectric environment.5 In a polar medium, the highly polar aromatic resonance structure Mz is stabilized relative to the quinonoid form Mq. This leads to a dipole moment of the excited state (μe M ) +13.7 D) that is smaller than that of the ground state (μg M ) +22.6 D), giving rise to a negative ∆μM (-8.9 D).6a This results in a negative solvatochromic behavior7 and a negative first-order molecular hyperpolarizability, âvec M .6 This negative value implies that âvec M is in an antiparallel orientation to the ground state dipole moment of M, μg . These properties are different from most stilbenoid derivatives, such as the protonated form ofM, 4-hydroxy-4′-N′-methylstilbazolium cation ([H-M]+), which shows a positive first-order hyperpolarizability value.6a Hence it is of considerable interest to develop potentially useful nonlinear optical crystals based on merocyanine dyes. However, in addition to a centrosymmetric packing, it was found that the crystallinity of the compoundM and its derivatives was too poor to grow single crystals with good optical quality. One of the strategies in crystal engineering is to dissect and insulate different types of intermolecular interactions from one another8 to induce a desired chromophoric alignment and to improve crystallinity, which motivated us to introduce a guest molecule to cocrystallize withM. We have found that by cocrystallization with nitrophenol derivatives based on the short hydrogen bond the cocrystal properties of the merocyanine dye,M1, are greatly improved.9 In this work, cocrystallization of equimolar of 2,4-dihydroxybenzaldehyde (DB) and M2 was carried out by cooling of methanol solutions or slowly evaporating the solvent. Deep red cocrystals 1 in the form of needles were obtained. The good optical quality of these crystals was checked with polarized light microscopy to show homogeneous extinction. The cocrystal 1 shows a strong second-harmonic generation (SHG) signal, comparable to that of 2-(N-prolinol)-5-nitropyridine (PNP)1a in the powder test at 1.3 μm, suggesting a highly non-centrosymmetric molecular arrangement of the chromophores in the cocrystal lattice. Single-crystal X-ray structure analysis shows that the unit cell of cocrystal 1 contains two molecules of M2 and DB together with one H2O molecule, in a non-centrosymmetric packing with space group P1.10 The frameworks, except for the hydrogen bonds of M2 as well as DB, are oriented in an antiparallel fashion with respect to each other and appear as pseudo-“centrosymmetric” structures within a unit cell (see Figure 1a). Further crystal structure analysis reveals that in the three-dimensional structure of the cocrystal 1 there are two types of hydrogen-bonded aggregates formed by DB and M2, respectively. Importantly, the proton plays different roles in the two aggregates. The dimeric DB aggregate (Figure 1a) is formed by two DB molecules which loose a proton to self-assemble as a hydrogen† Lab. fur Kristallographie, ETH-Zentrum, CH-8092, Zurich, Switzerland. * Corresponding authors. (1) (a) Bosshard, C.; Sutter, K.; Pretre, P.; Hulliger, J.; Florsheimer, M.; Kaatz, P.; Gunter, P. Organic Nonlinear Optical Materials; Gordon and Breach Science Publishers: Amsterdam, 1995; Vol. 1. (b) For a review of optical nonlinearities in chemistry, see: Chem. ReV. 1994, 94, 1-276 and the reference therein. (2) (a) Bosshard, C.; Sutter, K.; Schlesser, R.; Gunter, P. J. Opt. Soc. Am. 1993, B10, 867-884. (b) Marder, S. R.; Perry, J. W.; Yakymyshyn, C. P. Chem. Mater. 1994, 6, 1137-1147. (3) (a) Polymer for Second-Order Nonlinear Optics; Lindsay, G. A., Singer, K. D., Eds.; American Chemical Society: Washington, DC, 1995. (b) Bosshard, C.; Knopfle, G.; Pretre, P.; Follonier, S.; Serbutoviez, C.; Gunter, P. Opt. Eng. 1995, 34, 1951-1960. (4) âvec M ) 4200 × 10-40 m4/V, measured by electric-field-induced second-harmonic generation at λ ) 1.89 μm in DMSO (see: Dulic, A.; Flytzanis, C. Opt. Commun. 1978, 25, 402-406.) (5) (a) Buncel, E.; Rajagopal, S. J. Org. Chem. 1989, 54, 798-809. (b) Buncel, E.; Rajagopal, S. Acc. Chem. Res. 1990, 23, 226-231. (6) (a) Kanis, D. R.; Ratner, M. A.; Marks, T. J. Chem. ReV. 1994, 94, 195-242. (b) âvec M (exptl) ) -100 × 10-30 esu in methanol at 1.3 μm (see: Levine, B. F.; Bethea, C. G.; Wasserman, E.; Leenders, L. J. Chem. Phys. 1978, 68, 5042-5045.) (7) Botrel, A.; Beuze, A. L. J. Chem. Soc., Faraday Trans. 1985, 80, 1235. (8) Desiraju, G. R. Crystal Engineering; Elsevier: New York, 1989. (9) Pan, F.; Wong, M. S.; Gramlich, V.; Bosshard, C.; Gunter, P. Chem. Commun., in press. (10) (a) Crystal data for 1, C44H44N2O11: red prismatic crystal, triclinic, P1, a ) 8.262(3) A, b ) 10.039(4) A, c ) 13.491(4) A, R ) 69.73(2)°, â ) 82.99(11)°, γ ) 66.06(3)°, V ) 959.1(6) A3, Z ) 1, Fcalcd ) 1.345 mg cm-3, R ) 0.0291, wR ) 0.0397, GOF ) 1.19, residual electron density 0.12/-0.12 eA-3. (b) H2O in crystal 1 is lost at T ) 90(1) °C, measured by thermal gravitate (TG) analysis. 6315 J. Am. Chem. Soc. 1996, 118, 6315-6316
TL;DR: In this article, a polyurethane structure with a hemicyanine dye attached to the polymer side chain was synthesized by the step growth polymerization in a reaction between (E)-N-butyl-4-[2-[4]-bis(2-hydroxyethyl)amino]phenyl]ethenyl]pyridinium tetraphenylborate and 2,4-toluene diisocyanate.
Abstract: A new polyurethane structure with a hemicyanine dye attached to the polymer side chain was synthesized by the step growth polymerization in a reaction between (E)-N-butyl-4-[2-[4-[bis(2-hydroxyethyl)amino]phenyl]ethenyl]pyridinium tetraphenylborate and 2,4-toluene diisocyanate. The molecular weight of the final product was determined to be Mn = 12 000 and Mw/Mn = 1.67. The polymer is soluble in dimethylformamide and can be processed into optical quality films by spin casting. No evidence of melting was detected by differential scanning calorimetry, suggesting that this polymer presents an amorphous phase. It shows a glass transition temperature of 121 °C. The macroscopic second-order hyperpolarizability χ(2) of this polyurethane was determined by measuring the second harmonic generation (SHG) for a thin polymer film. The χ(2) value was in the range 1.8 × 10-7 to 5.0 × 10-7 esu, depending upon poling conditions. This high second-order activity seems to prove the earlier prediction about a possible enhancem...
TL;DR: In this article, three specific variations of the perturbation-theoretic approach are analyzed and it is concluded that the relaxation/infinite-frequency method is a satisfactory approximation for the nonlinear optical vibrational hyperpolarizabilities.
Abstract: Various approximate methods for the calculation of vibrational second hyperpolarizabilities are assessed on the basis of results for CH4, NH3, H2O, HF, and CO2. Three specific variations of the perturbation‐theoretic approach are analyzed. These are defined by the types of terms retained in expansions which involve electrical and mechanical anharmonicities. The lowest‐order approximation being the double‐harmonic one and the next higher one the relaxation method. For the dynamic hyperpolarizabilities, the replacement of the optical frequencies (ω) by ω→∞ (the infinite‐frequency approximation) is also explored. On the evidence at hand it is concluded that the relaxation/infinite‐frequency method is a satisfactory approximation for the nonlinear optical vibrational hyperpolarizabilities.
TL;DR: In this article, the vibrational contributions to the polarizability, and first and second hyperpolarizability tensors of p -nitroaniline have been evaluated for different optical processes by adopting the infinite frequency or enhanced approximation.
TL;DR: In this paper, the bimetallic sesquifulvalene complexes [{CpFe(η5-C5H4)}Z{η7-C7H6)Cr-(CO)3}]BF4 (2BF4) have been synthesized with different bridging functions.
Abstract: In order to construct bimetallic organometallic donor–acceptor complexes with nonlinear optical (NLO) properties, the bimetallic sesquifulvalene complexes [{CpFe(η5-C5H4)}Z{η7-C7H6)Cr-(CO)3}]BF4 (2BF4) have been synthesized with different bridging functions Z (2a: Z = - 2b: Z = C2; 2c: Z (E)-C2H2). X-ray structure determinations show that 2a BF4 and 2c BF4 crystallize in acentric space groups (P41, P212121), whereas crystalline 2b BF4 has the centric space group P21/c. The organometallic fragments in 2a adopt a transoid conformation, those in 2b and 2c are cisoid. The cyclo-C5 and cyclo-C7 rings of the sesquifulvalene ligands are almost coplanar; this allows an optimum electronic interaction between the ferrocenyl donor and the [η7-C7H6)Cr(CO)3]+ acceptor moiety in the crystalline state. Cyclovoltammetric studies show an electrochemically reversible one-electron oxidation ( > 0 mV vs. FeH/FcH+, FcH = ferrocene) and an irreversible one-electron reduction (≤–900 mV), which are assigned to the ferrocenyl and [(η7-C7H6)Cr(CO)3]+ units, respectively. UV/vis spectra reveal low-energy absorptions for 2a–c at about λ=600 nm, showing strong negative solvatochromism. These absorption maxima are related to a charge-transfer excitation between the ferrocenyl and the [(η7-C7H6)Cr(CO)3]+ groups, indicating considerable nonlinear optical properties. Determination of the first hyperpolarizability β by means of hyper Rayleigh scattering yields exceptionally large β values: β(2b) = 570 × 10−30 esu and β(2c) = 320 × 10−30 esu. These unexpectedly large β values are explained by resonance enhancement.
TL;DR: In this article, novel homo- and heterobimetallic complexes have been synthesized, and their nonlinear optical properties were evaluated, including the effects upon the hyperpolarizability of chain length, configuration of the metal donor group, and kind of metal acceptor group.
TL;DR: The first hyperpolarizability of two tricyanovinylthiophene nonlinear optical chromophores were determined using second harmonic, hyper-Rayleigh, scattering as discussed by the authors.
Abstract: First hyperpolarizabilities (β) of two tricyanovinylthiophene nonlinear optical chromophores were determined using second harmonic, hyper‐Rayleigh, scattering The use of an external standard in the determinations is compared with the previous use of an internal standard The first hyperpolarizability of the well‐known chromophore 4 dimethylamino 4′ nitrostilbene (DANS) was also determined using the external standard method and its value is compared to those in the literature A new method of analyzing the hyper‐Rayleigh scattering signal by recording a histogram of the scattered energy is reported This method is shown to give more reliable results in a shorter period of time than the usual static gate method The histogram function provides additional information in the form of the histogram width which is shown to be an indication of the mean‐square concentration fluctuations of the chromophores in solution The effects of molecular interactions on the concentration dependence of the hyper‐Rayleigh scattering signal is discussed It is shown that depending on the concentration range, the β value of para‐nitroaniline, used as the external standard, can agree with two different values reported in the literature Results on the depolarization ratio of the hyper‐Rayleigh scattered light from one of the tricyanovinylthiophene chromophores are presented At low concentration the depolarization ratio agrees with the theoretically predicted value based on C2v symmetry However, at higher concentration the measured depolarization ratio increases indicating molecular interactions
TL;DR: In this article, the frequency dependence of the refractive index n and dipole polarizability α of Hg vapor was measured and the Cauchy moments S(−2) = 33.91(34), S( −4) = 279.8(8.4), and S((−6) = 14 100(2810) have been obtained.
Abstract: We report interferometric measurements of the frequency dependence of the refractive index n and the dipole polarizability α of Hg vapor. From the measured dispersion of the dipole polarizability the Cauchy moments S(−2) = 33.91(34), S(−4) = 279.8(8.4), and S(−6) = 14 100(2810) have been obtained. The static limit S(−2) is in good accordance with ab initio calculations and results obtained from dielectric constant measurements. The Cauchy moments are used to predict approximations of the dispersion interaction energy constant C6 = 255 au and the second hyperpolarizability γ(0) = 2.2 × 104 au.
TL;DR: In this article, it was shown that the low frequency collective modes of quasilinear polymers can contribute to the vibrational polarizability and hyperpolarizability despite the fact that their infrared or Raman intensity vanishes in the infinite chain limit.
Abstract: It is shown that the low frequency collective modes of quasilinear polymers can contribute to the vibrational polarizability and hyperpolarizability despite the fact that their infrared or Raman intensity vanishes in the infinite chain limit. The most significant of these modes are characterized and the dynamic vibrational nonlinear optical (NLO) properties are obtained, at the doubly harmonic Hartree–Fock level of approximation, from static field calculations on polyacetylene as well as polyyne, polysilane, and polyethylene. Comparison is made to a pair of unit cell modes, one Raman‐active and the other infrared‐active, that are expected to generate a large vibrational hyperpolarizability. The combined effect of the collective and unit cell vibrations is potentially of considerable importance for the enhancement of NLO properties. Further studies are suggested to exploit this potential.
TL;DR: In this article, an improved method for measuring the first order hyperpolarizability of organic nonlinear optical materials in solution by the hyper-Rayleigh scattering technique was proposed.
TL;DR: In this article, the static second hyperpolarizabilities (γ) for neutral, anion radical and dianion states for a symmetric condensed-ring conjugated system, i.e. pentalene, are calculated by the use of ab initio molecular orbital methods with extended basis sets.
TL;DR: In this article, the second-order nonlinear optical response of amine and phenol/ether derivatives (1−8) has been evaluated using experimental and theoretical techniques, and it was shown that N-phenyl substitution of 4-nitroaniline (1) produces a greater increase in molecular hyperpolarizability than N-methyl substitution.
Abstract: The second-order nonlinear optical response of amine and phenol/ether derivatives (1−8) has been evaluated using experimental and theoretical techniques. Electric-field-induced second-harmonic generation (EFISH) measurements establish that N-phenyl substitution of 4-nitroaniline (1) produces a greater increase in molecular hyperpolarizability than N-methyl substitution. In contrast, O-phenyl substitution of 4-nitrophenol (6) produces a smaller increase in hyperpolarizability than O-methyl substitution. Neither the enhancement of hyperpolarizability upon N-phenyl substitution nor the differential substituent effect is anticipated on the basis of qualitative arguments. Careful theoretical analysis using semiempirical sum-over-states and finite field calculations provide explanations for both observed effects.
TL;DR: In this article, the evolution in the static longitudinal polarizability and second hyperpolarizability of the C4H2 through C54H2 oligomers of polyyne is studied at the Hartree-Fock level of theory.
Abstract: The evolution in the static longitudinal polarizability and second hyperpolarizability of the C4H2 through C54H2 oligomers of polyyne is studied at the Hartree–Fock level of theory. We find that the calculated values are highly sensitive to the adopted geometry. Using improved geometries, new extrapolation procedures and careful finite field determinations we extend earlier work by others so as to provide reliable estimates for the above properties in the infinite polymer limit.
TL;DR: The first hyperpolarizability, beta, of Crystal Violet dye was measured and the resonance-free beta value, beta(0), was found to be comparable with that of the dipolar dye Disperse Red 1 but with the nonlinearity-transparency trade-off worse for the octupole.
Abstract: A hyper-Rayleigh scattering (HRS) system based on an optical parametric power oscillator is described. The first hyperpolarizability, β, of Crystal Violet dye was measured at 1450 and 1500 nm. The resonance-free β value, β(0), for this octupole was found to be comparable with that of the dipolar dye Disperse Red 1 but with the nonlinearity–transparency trade-off worse for the octupole. The discrepancy in β(0) with that reported previously is explained in terms of resonance and the adequacy of the octupolar three-state model. The possibility of dye aggregation by solvent-dependent HRS is investigated.
TL;DR: In this article, the third-order optical nonlinearity of 10Li 2 O · 15ZnO · 70Bi 2 O 3 (mol%) glass samples containing W, Pb, Mo, Ba and Nb with high refractive indices was evaluated by third harmonic generation method.
Abstract: Third-order optical non-linearity of 10Li 2 O · 15ZnO · 70Bi 2 O 3 (mol%) glass samples containing W, Pb, Mo, Ba and Nb with high refractive indices was evaluated by third harmonic generation method. These glasses were prepared by conventional melt-and-quenching technique. The χ (3) values derived were close to some TeO 2 -based glasses which have the largest χ (3) among homogeneous glasses. χ (3) as large as 2.1 × 10 −12 esu was obtained for glasses containing WO 3 or PbO. The hyperpolarizability ( α (3) ) of BiOBi bonds in the glasses was found to be comparable to that of TeO 4 unit.
TL;DR: In this article, the static second hyperpolarizability (γ) for a small size open-shell system containing a nitroxide radical group, H 2 NO, was studied by using ab initio molecular orbital and density functional methods.
TL;DR: In this paper, the quadratic hyperpolarizability of donor polyenes was investigated using the electric field-induced second-harmonic (EFISH) generation technique, at 1.907 µm in chloroform.
TL;DR: In this article, the third-order optical nonlinearities of -toluene solutions were studied employing transient degenerate four-wave mixing (DFWM) and z-scan techniques using 0.5 ps laser pulses at 497 nm.
Abstract: The third-order optical nonlinearities of - toluene solutions are studied employing transient degenerate four-wave mixing (DFWM) and z-scan techniques using 0.5 ps laser pulses at 497 nm. The concentration dependence of the of the solution and both the sign and the magnitude of the real and imaginary parts of the third-order susceptibility of are obtained. The molecular second hyperpolarizability of is found to be . The role of nonlinear absorption and its influence on the DFWM signal is discussed. Finally a comparison of our experimental data with other data in the literature is given.