Harmonic Light Scattering

Raman scattering Infrared absorption Inelastic harmonic light scattering (Hyper-Raman) Neutron inelastic scattering Stimulated Raman scattering... 

S. Kielich. Second harmonic light scattering by dense, isotropic media. Acta Phys. Polonica, 33 89-104 (1968). 

S. Kielich, J. R. Lalanne, and F. B. Martin, second harmonic light scattering induced in liquids by fluctuational electric fields of quadrupolar molecules. Acta Phys. Polonica, A, 47 479 82 (1972). 

Experimentally, mainly two techniques - the electric field induced second harmonic generation (EFISH) and hyper-Rayleigh scattering (HRS, also termed harmonic light scattering method) - are used in order to determine in solution the experimental value of the quadratic hyperpolarizability of molecular NLO chromophores. 

Schuerer B, Hoffmann M, Wunderlich S, et al Second harmonic light scattering from spherical polyelectrolyte brushes, J Phys Chem C 115 18302—18309, 2011. 

Schiirer B, Wunderhch S, Sauerbeck C, Peschel U, Peukert W Probing colloidal interfaces by angle-resolved second harmonic light scattering, Phys Rev B 82 241401, 2010. 

Experimental and theoretical results are presented for four nonlinear electrooptic and dielectric effects, as they pertain to flexible polymers. They are the Kerr effect, electric field induced light scattering, dielectric saturation and electric field induced second harmonic generation. We show the relationship between the dipole moment, polarizability, hyperpolarizability, the conformation of the polymer and these electrooptic and dielectric effects. We find that these effects are very sensitive to the details of polymer structure such as the rotational isomeric states, tacticity, and in the case of a copolymer, the comonomer composition. 

We have shown in this paper the relationships between the fundamental electrical parameters, such as the dipole moment, polarizability and hyperpolarizability, and the conformations of flexible polymers which are manifested in a number of their electrooptic and dielectric properties. These include the Kerr effect, dielectric polarization and saturation, electric field induced light scattering and second harmonic generation. Our experimental and theoretical studies of the Kerr effect show that it is very useful for the characterization of polymer microstructure. Our theoretical studies of the NLDE, EFLS and EFSHG also show that these effects are potentially useful, but there are very few experimental results reported in the literature with which to test the calculations. More experimental studies are needed to further our understanding of the nonlinear electrooptic and dielectric properties of flexible polymers. 

Moreaux, L., Sandre, O., Charpak, S., Blanchard-Desce, M., and Mertz, J. 2001. Coherent scattering in multi-harmonic light microscopy. Biophys. J. 80 1568-74. 

No pure compound with a peak at 375 m/j has been found to date, but occurrence of this peak certainly suggests that the compound responsible is related to the furfurals. An optical relationship also exists. When the colorant index is plotted against the frequency, the two peaks of 5-(hy-droxymethyl)-2-furaldehyde are found at 1305 and 1055 fresnels (sec.-1 X 1012). The peak of the unknown is at 805 fresnels, which is an exact, harmonic difference. The next harmonic would be at 555 fresnels or 540 m/j, in the general region in which the minima are found. The harmonic possible at 540 m/i is, unfortunately, in the region where light-scattering phenomena must also receive consideration. 

The source S(t) = -pod2PNL(t)/dt2 corresponding to (4.22) has a component at frequency 2lo and complex amplitude S(2lo) = 4pb0u)2dE(uj)E u), which radiates an optical field at frequency 2co (wavelength Ao/2). Thus the scattered optical field has a component at the second harmonic of the incident optical field. Since the amplitude of the emitted second-harmonic light is proportional to S(2lo), its intensity is proportional to S 2uj) 2au)id I2, where I = E(uj) 2/2r/ is the intensity of the incident wave. The intensity of the second-harmonic wave is therefore proportional to d2, to 1/Ag, and to I2. Consequently, the efficiency of second-harmonic generation is proportional to / = P/A, where P is the incident power and A is the cross-sectional area. It is therefore essential that the incident wave have the... 

Values of A " = A(— 2linear light scattering at doubled ftequenqr by gases and liquids or from second-harmonic generation by a gas in the presence of a static electric field. We obviously have in mind substances composed of dipolar molecules undergoing reorientation by the static field. ... 

Since, in HRS, there is no preferred orientation induced by an additional static field, there is the possibility of varying the experimental conditions in order to increase the number of independent observables. The number of theoretically possible independent observations, and hence the number of tensor components that can be obtained by HRS, is at most five. For parametric light scattering, this number is six, due to the possibility of distinguishing between the two optical fundamental fields [20]. The experimental difficulty has precluded the determination of this number of components. What is experimentally realistic in HRS is an additional depolarization measurement, apart from the classical measurement of the intensity of the second-order incoherent scattered light. The two measurements, the total intensity measurement and the depolarization ratio (or two intensity measurements, one with parallel and one with perpendicular polarization for fundamental and second harmonic), represent two independent observables and allow the experimental determination of two tensor components. For molecules of C2 symmetry, these are and P xxy resulting for the total intensity measurement in Eqn. (21),... 

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