Showing papers on "Hyperpolarizability published in 1992"

Hyper‐Rayleigh scattering in solution

Abstract: The experimental setup for the implementation of a new technique to determine the hyperpolarizability of nonlinear optical molecules in solution is presented The new technique, hyper‐Rayleigh scattering in solution [K Clays and A Persoons, Phys Rev Lett 66, 2980 (1991)], has the advantage over the electric‐field‐induced second‐harmonic generation technique that the dipole moment μ and the second hyperpolarizability γ do not have to be independently determined to obtain the first hyperpolarizability β No electric field is needed to lower the intrinsic symmetry of the isotropic solution, leading to a simpler cell design and a simpler local field factor The internal reference method, when applicable, completely eliminates the local field factor With the technique presented, values of the first hyperpolarizability β of 23×10−30 esu for para‐nitroaniline (PNA), 105×10−30 esu for 4‐methoxy‐4’‐nitrostilbene (MONS), and 95×10−30 esu for 4‐hydroxy‐4’‐nitrostilbene (HONS) dissolved in chloroform have been obtained

Quadratic response functions for a multiconfigurational self‐consistent field wave function

Abstract: We describe an efficient implementation of the quadratic response function for a multiconfiguration self‐consistent field reference wave function. The quadratic response function determines the hyperpolarizability and its residues determine the two‐photon transition matrix elements and the transition matrix elements between excited states. We report sample calculations for the hyperpolarizability of Ne and for the two‐photon transition matrix elements of Ne and H2.

Design of chromophoric molecular assemblies with large second-order optical nonlinearities. A theoretical analysis of the role of intermolecular interactions

Abstract: The role and nature of intermolecular interactions in determining quadratic nonlinear optical macroscopic hyperpolarizabilities are investaged using the INDO/S (ZINDO) sum-over excited particle-hole-states formalism on clusters (dimers and trimers) of archetypical donor/acceptor organic π-electron chromophore molecules. It is found that the calculated aggregate hyperpolarizability depends strongly on relative molecular orientations, exhibiting the largest values in slipped cofacial arrangements, where the donor substituent of one molecular unit is in close spatial proximity to the acceptor subsituent of the nearest neighbor

Nitrocalix [4]arenes as Molecules for Second-Order Nonlinear Optics

Abstract: The frequency-doubling of 820 nm laser light is o­ne of the properties of a series of nitrocalix-[4]arenes making them suitable, in principle, for the construction of a blue laser. Derivative 1 is the most promising, since it displays the greatest hyperpolarizability and the largest dipole moment and is stable as a film in a polymer matrix for long periods.

The calculation of frequency‐dependent hyperpolarizabilities including electron correlation effects

Abstract: The theory for the calculation of the frequency-dependent hyperpolarizabilities β(−2ω; 0, ω), β(−ω; 0, ω), and β(0; ω, −ω) is discussed. New relations between these tensors are derived for those wave functions that obey the time-dependent Hellmann–Feynman theorem (e.g., the self-consistent field [SCF] or the exact wave function). Using second-order Moller–Plesset perturbation theory (MP2), expressions are obtained for the hyperpolarizabilities in terms of derivatives of appropriately defined linear polarizability tensors with respect to a static electric field. Results are presented for ammonia and formaldehyde for the optical Kerr effect and for secondharmonic generation. These results indicate that it is desirable to determine the frequency-dependent contribution to the hyperopolarizability at the MP2 rather than the SCF level of theory, in cases where the static hyperpolarizability has a large contribution from electron correlation and/or where the frequency-dependent contribution may be more significant, such as for secondharmonic generation.

Quadratic nonlinear-optical properties of a new transparent and highly efficient organic–inorganic crystal: 2-amino-5-nitropyridinium-dihydrogen phosphate (2A5NPDP)

Abstract: Linear and quadratic nonlinear-optical (NLO) properties of a new organic–inorganic crystal, 2-amino-5-nitro-pyridinium-dihydrogen phosphate (2A5NPDP), are reported. 2A5NPDP was designed to display high NLO efficiency by incorporating highly polarizable organic molecules arranged in a polar order between phosphate polyanion sheets. The material is transparent in the visible and the near-IR (from 0.42 to 2 μm) with favorable phase-matching (PM) conditions for second-harmonic generation in the 1-μm region. Crystal nonlinear coefficients responsible for PM were determined by the Maker fringe method, leading at 1.06 μm to d15 ≅ 7.2 pm/V and d24 ≅ 1.3 pm/V. The measured crystal coefficients significantly depart from oriented gas model calculations based on molecular hyperpolarizability values measured in an aprotic solution, thus suggesting important crystal-field effects and protonation contributions. Thermal sensitivity of the PM angle at 1.34 μm is found to be 155″/°C, which is considerably larger than typical values of inorganic NLO crystals and opens the way to efficient thermal tuning of phase-matched processes.

Semiempirical calculations of the polarizability and second-order hyperpolarizability of fullerenes (C60 and C70), and model aromatic compounds

Abstract: The authors present the results of molecular orbital calculations of the polarizability and second-order hyperpolarizability of several aromatic hydrocarbons and C{sub 60} and C{sub 70}. For the hydrocarbons, the authors look at the question of what types of additions to the ring structure have the largest effects on polarizability. The authors are interested in the ability to predict the microscopic properties of molecules which will affect their non-linear optical properties.

Nonresonant third‐order optical nonlinearity of all‐carbon molecules C60

Abstract: The nonresonant third‐order hyperpolarizability of all‐carbon molecules C60 is measured by nanosecond degenerate four‐wave‐mixing experiment in C60 toluene solution. The value of γ1111 measured is 1.6×10−31 esu, which corresponds to an estimated value of the third‐order nonlinear optical susceptibility χ(3)1111E = 3.3 × 10−9 esu for the solid compound.

Linear and nonlinear polarizabilities of trans‐polysilane from ab initio oligomer calculations

Abstract: Linear and nonlinear static electronic polarizabilities of the σ‐conjugated polymer trans‐polysilane (t‐PSi) are obtained at the Hartree–Fock level by extrapolation of ab initio calculations on the oligomers H3Si–(SiH2)N–SiH3 (N odd). For the longitudinal components, in particular, a 6–31 G basis is shown to yield accurate values if the chains are long enough. No computational advantage is found in using effective core potentials. Chain lengths through N=13 are sufficient to give limiting infinite chain polarizabilities with relatively small uncertainty. The calculated longitudinal linear polarizability per SiH unit is about the same as the corresponding property in the prototype π‐conjugated polymers polyacetylene (PA) and polydiacetylene (PDA), but the longitudinal second hyperpolarizability is significantly less in the σ‐conjugated polymer. In t‐PSi the conjugation length is about half that in either PA or PDA. Frequency‐dependent vibrational distortion contributions are estimated in the doubly harmoni...

Accurate variational calculations of energies of the 2 (2)S, 2 (2)P, and 3 (2)D states and the dipole, quadrupole, and dipole-quadrupole polarizabilities and hyperpolarizability of the lithium atom.

Abstract: The combined configuration-interaction\char21{}Hylleraas method has been used to calculate the energies for the ground 2 $^{2}$S and the excited 2${\mathrm{}}^{2}$P and 3 $^{2}$D states of the lithium atom. The energies obtained, -7.478 060 1 a.u. for the 2 $^{2}$S state, -7.410 155 4 a.u. and -7.335 523 1 a.u. for the 2 $^{2}$P and 3 $^{2}$D states, respectively, are the lowest nonrelativistic variational upper bounds found so far. Ionization potentials, lifetimes, dipole oscillator strengths and their sums, dynamic dipole, quadrupole and dipole-quadrupole polarizabilities, and the static second hyperpolarizability are also reported and compared with experimental and other theoretical results.

Nonlinear optical properties of the fullerene (C60) molecule: theoretical and experimental studies

Abstract: Using the MZINDO-TDCPHF approach, C{sub 60} frequency-dependent molecular linear polarizability and second hyperpolarizability have been calculated in this paper. These values are, respectively, 13 and 30-34 times larger than those for benzene. 29 refs., 1 fig., 2 tabs.

The design, synthesis, and evaluation of chromophores for second‐harmonic generation in a polymer waveguide

Abstract: In order to develop nonlinear optical chromophores for frequency doubling applications, it is important to understand the magnitudes of the relevant chromophore properties that will be required In this paper the use of organic polymers with attached optically nonlinear chromophores to form waveguide second‐harmonic‐generation devices will be discussed In particular, the use of such a frequency doubling device in optical storage applications will be considered To this end limits on the quantity μβ are obtained where μ is the dipole moment and β the hyperpolarizability Experimental values for electron donor/acceptor‐substituted benzenes, stilbenes, and tolanes are compared to these requirements None of the chromophores treated here have both sufficiently high optical nonlinearity and sufficiently low optical absorption at a doubled optical frequency of 400 nm to be practical in the specific application described

Crystal structures and non-linear optical properties of borane derivatives

Abstract: [4′-(Dimethylamino)biphenyl-4-yl]dimesitylborane (BNB) and 4-[4′-(Dimethylamino)pnenylazo]phenyldimesityl-borane (BNA) have been investigated by X-ray diffraction; crystallographic data were used to calculate dipole moments in the ground state and the hyperpolarizability coefficient βo was measured by the EFISH technique for each derivative. The results show that the trivalent boron group is an efficient electron acceptor compared to other known acceptors such as the nitro group. Organoboron derivatives are promising candidates for nonlinear optical materials.

Local density functional calculations of the polarizability and second-order hyperpolarizability of fullerene-C60

Abstract: Local density functional (LDF) calculations of the value of α and γ for benzene and C 60 (I h ) have been made with a double numerical basis set augmented with polarization functions. The geometries were optimized resulting in r(C-C)=1.389 A for benzene and r(C-C)=1.442 A and r(C=C)=1.386 A for C 50 . The dependence of α and γ for benzene on the computational parameters of the mesh quality, field strength, and SCF convergence was studied. Values of α=1.012×10 -23 cm 3 and γ=6.24×10 -36 esu were calculated for benzene

Ab initio molecular orbital study of nitrogen-containing polyenes with donor-acceptor substituents: dipole moment and static first hyperpolarizability

Abstract: Ab initio CPHF calculations have been carried out in order to clarify the relationship between dipole moment (μ) and first hyperpolarizability (β) of nitrogen-containing π-conjugated polyenes with donor-acceptor subsitutents attached on the end. The systematic calculations on the polyene-like model compounds indicate that nitrogen-atom substitution in π-conjugated systems (N subsitutions) fluctuate μ-values and gradually decrease β-values with increasing the number of substituted nitrogen atoms. From the calculated results, several tendencies are recognized for the changes of μ- and β-values induced by the N substitution

Calculation of the polarizability and hyperpolarizability tensors, at imaginary frequency, for H, He, and H2 and the dispersion polarizability coefficients for interactions between them

Abstract: Accurate calculations of the polarizability and hyperpolarizability tensors at imaginary frequency, α(−iω;iω) and γ(−iω;iω,0,0), for H, He, and H2 are reported for a range of frequencies (ω) useful for Gauss–Legendre quadrature. They have been used to evaluate the dispersion polarizability coefficients which govern the nonclassical contribution to the change in electronic polarizability due to long‐range interactions between the aforementioned species. Previously, these coefficients have only been found by more approximate methods. The basis of the calculations of α(−iω;iω) and γ(−iω;iω,0,0) was the sum‐over‐states method and, for He and H2, electron correlation was explicitly taken into account. With respect to γ(−iω;iω,0,0), we believe these to be the first calculations of any kind.

A study of basis set and electron correlation effects in the ab initio calculation of the electric dipole hyperpolarizability of ethene (H2C=CH2)

Abstract: We report finite‐field self‐consistent field (SCF) and many‐body perturbation theory calculations of the dipole polarizability and hyperpolarizability of ethene. Large Gaussian‐type basis sets have been used to ensure the determination of reliable, near Hartree–Fock values for all the independent components of the dipole hyperpolarizability tensor γαβγδ. The calculated SCF values of γ display strong basis set dependence. Electron correlation changes drastically the SCF picture of γαβγδ. The most important effect is the increase by nearly 70% of the component parallel to the double bond, γzzzz (molecular plane xz). It is found that the contribution from the fourth‐order triple substitutions T4, dominates the fourth‐order correction to the SCF value for almost all components of γ. The best SCF values obtained in this work are (in atomic units), γxxxx=3466, γyyyy=11 080, γzzzz=3351, γxxyy=2390, γyyzz=2936, γzzxx=1660, and γ=6374e4a04Eh−3. The estimated electron correlation corrections (Δ corr) are 431±79, −...

Nonlinear optical properties of Langmuir–Blodgett monolayers: Local‐field effects

Abstract: Detailed measurements of the macroscopic second‐order optical nonlinearity χ(2)(2ω,ω,ω) of Langmuir–Blodgett dye‐doped monolayers are reported. The observed deviations from a linear behavior of χ(2) with increasing surface density are shown to be due to local‐field effects. In order to calculate these local‐field factors for disordered systems, a novel Monte Carlo type calculation is introduced. This calculation not only accounts for density variations in the monolayers but also incorporates the effect of off‐diagonal elements of the (microscopic) linear susceptibility tensor. Quantitative agreement is found between the calculations and the experimental results using only the molecular hyperpolarizability as a free parameter. A method is presented to determine the tilt angle of the chromophores in Langmuir–Blodgett monolayers from the anisotropy of the linear absorption. The tilt angle determined this way is in excellent agreement with a determination by second‐harmonic generation.

Static and dynamic optical nonlinearities in conjugated polymers: Third-harmonic generation and the dc Kerr effect in polyacetylene, polyparaphenylene vinylene, and polythienylene vinylene.

Abstract: The static and dynamic second hyperpolarizability tensors of oligomers of polyacetylene, polyparaphenylene vinylene, and polythienylene vinylene are evaluated by means of the valence effective Hamiltonian (VEH) method The sum-over-states (SOS) approach is exploited, by constructing excited states from both single- and double-electron excitations The ab initio coupled perturbed Hartree-Fock method is also applied in the case of small representative molecules such as benzene, thiophene, styrene, and thienylethylene in order to test the validity of the VEH-SOS approach The VEH-SOS results are found to be comparable with the ab initio results The length dependence of the static hyperpolarizability is analyzed and found to scale with the optical gap evolution of the different oligomers The dynamic properties are presented in terms of third-harmonic generation and the dc Kerr effect

Second-harmonic generation in the crystalline complex antimony triiodide–sulfur

Abstract: Crystals of the 1:3 complex between antimony triiodide and sulfur, SbI3 * 3S8, are found to possess a high second-order optical nonlinearity. The powder second-harmonic generation efficiency is found to be approximately half of that of the isostructural complex of iodoform with sulfur, CHI3 * 3S8. Second-harmonic generation can be phase matched. The phase-matching angle of type I is found to be approximately 30° at the fundamental wavelength 1.064 μm. The Maker fringes’ measurements give χ222(2)≅16 pm/V, χ333(2)≅23 pm/V and χ311(2)≅15 pm/V, for the values of the components of the second-order susceptibility tensor. The third-rank hyperpolarizability tensor β was decomposed into irreducible parts; the norms of the vector part and the septor (octupolar) part in the SbI3 * 3S8 complex were evaluated to be βυ = 52.1 × 10−40 m4/V and βs = 20.2 × 10−40 m4/V, respectively.

Higher analytic derivatives

Abstract: This is the third in a series of papers on the ab initio calculation of the third and fourth derivatives of the energy of a molecule. In this paper derivatives with respect to electric field components, as well as with respect to nuclear coordinates are considered. A knowledge of these derivatives yields, in particular, the dipole surface up to third order, the polarizability surface up to second order, the hyperpolarizability surface up to first order, and the second hyperpolarizability. These quantities may be obtained with minimal modification of the fourth derivative of the SCF energy program described earlier. The dipole third derivatives, the polarizability second derivatives, and the hyperpolarizability first derivatives are calculated analytically for the first time. Together with the anharmonic energy derivatives, the dipole surface enables the calculation of infrared intensities for fundamental, overtones and combination bands. The scattering intensities in the Raman effect for fundamentals, ove...

Ab initio CPHF calculations of the static polarizability and second hyperpolarizability of small molecules: Comparisons between standard and moderately large basis sets augmented with diffuse functions

Abstract: Static polarizability and second hyperpolarizability have been calculated for a number of small moleculesCO2, OCS, CS2, C2H2, C2H6, C3H8, cyclo-C3H6, C3H4, C3H6, SiH4, Si2H6in the framework of the coupled-perturbed Hartree-Fock (CPHF) theory. The linear and nonlinear coefficients have been calculated with standard Gaussian basis sets and 3-21G bases moderately enlarged with diffuse functions. It is shown that the parallel component of the polarizability saturates rapidly, which suggests that a 3-21G basis containing s and p diffuse functions is sufficient to reproduce αzz. For the αxx and αyy components, a 3-21G basis with s, p, and d diffuse functions is required. In general, the concordance between α computed with this basis set and the experimental static polarizability is at least of the order of 80%. On the contrary, the computation of the second hyperpolarizability with the same basis set for CO2, CS2, and C2H2 gives values that are 30% too low, compared to the experimental value. Better results are observed for ethane, propane, and cyclopropane for which the error is lower than 50%. The better agreement observed for the saturated compounds can probably be explained by their saturated character.

The first molecular electronic hyperpolarizabilities of highly polarizable organic molecules: 2,6-di-tert-butylindoanilines

Abstract: The first molecular hyperpolarizabilities (β) of a series of 2,6-di-tert-butylindoanilines, measured by electric-field-induced second harmonic generation are somewhat more sensitive to donor strength than was found for analogously substituted nitrostilbenes, and dimethylindoaniline has a β roughly twice that of its 2,6 di-tert-butylated analogue, measured in chloroform; solvatochromic measurements on the former compound suggest that this decrease in hyperpolarizability is consistent with a bound-solvent effect.