Showing papers on "Hyperpolarizability published in 1974"

Molecular hyperpolarizabilities determined from conjugated and nonconjugated organic liquids

Abstract: The magnitude and sign (positive) of the molecular hyperpolarizability γ has been determined for several mixtures of nitrobenzene and benzene. This has allowed the testing of the adequacy of Onsager's local field factors, which are found to be valid. By comparing γ of nitrobenzene with that of nitromethane, we find that the delocalized conjugated electrons are an order of magnitude more effective in contributing to γ than are the localized nonconjugated electrons.

Dispersion of the nonlinear optical susceptibilities of organic liquids and solutions

Abstract: The dispersion of the third order optical nonlinear polarizabilities of benzene, chlorobenzene, and nitrobenzene is measured in the vicinity of Raman active vibrations. Observation of interference between resonant and nonresonant contributions determines the magnitude and phase of the electronic hyperpolarizability. Shifts in the frequency and linewidth of the interference minima occur when additional components such as CCl4, CS2, or 2,5‐diphenyloxazole are added to the solution. Analysis of the resulting line shape yields the hyperpolarizability of the solute species.

Measurements of hyperpolarizabilities for some halogenated methanes

Abstract: dc Electric‐field induced optical second‐harmonic generation has been measured for CH4, CH3F, CH2F2, CHF3, CF4, CClF3, and CBrF3. For CH4 and CF4 the third order hyperpolarizability χ(−2ω; 0,ω,ω) is obtained directly. For the other (dipolar) molecules, a bond additivity estimate for χ(−2ω; 0,ω,ω) is used to extract the second order hyperpolarizability χ(−2ω;ω,ω).Results are compared with various data from the literature: calculated hyperpolarizabilities, and measurements of optical harmonic generation, optical mixing and the Kerr effect. The degree of consistency of the experimental data with a bond additivity model is discussed.

Absolute signs of hyperpolarizabilities in the liquid state

Abstract: We discuss several techniques for the determination of the absolute sign of molecular hyperpolarizabilities in the liquid state. One of these techniques is the comparison of the phase of the harmonic field produced by the liquid with that generated by the glass walls of the electroded cell. Another method is the phase comparison with a crystal quartz plate of known absolute orientation. Using these methods we determine that the hyperpolarizability of nitrobenzene is positive, i.e., the molecular nonlinearity and dipole moment are parallel. By mixing nitrobenzene with other liquids, we can readily determine their absolute signs, e.g., we have found that liquid CH3I is positive in agreement with measurements in the gas phase.

Spectral theory of molecular rotation-induced broadening of hyper-Raman lines in liquids

Abstract: The spectral line shape of hyper-Raman light scattering in liquids is calculated by the method of irreducible spherical tensors and the theory of rotational Brownian motion. The line broadening due to rotational molecular motion in the liquid is expressed by way of relaxation times τ and is found to depend on nonlinear molecular parameters ∣B∣2, which are quadratic functions of the derivatives with respect to appropriate normal coordinates of the hyperpolarizability tensor elements b. Tables of ∣B∣2 are adduced for all vibration symmetries of spherical-top and symmetric-top molecules. The tensor elements of scattered light intensity are calculated for linearly and circularly polarized incident light. Investigation of hyper-Raman spectral line broadening is seen as a source of new data on the dynamics of molecules in the liquid state and on their nonlinear optical properties.