Low-frequency scattering by rectangular dielectric particles

The field scattered by a homogeneous isotropic dielectric particle illuminated by a low-frequency plane electromagnetic wave is expressed in terms of a single polarizability tensor which is a function of only the geometry of the particle and a material parameter τ representing either the relative permittivity or permeability of the dielectric. The mathematical formulation is specialized to the case of a rectangular parallelepiped and numerical techniques are developed for computing the tensor elements. Specific data are presented for the tensor elements of rectangular parallelepipeds having square cross sections and are compared to the results obtained for spheroids and right circular cylinders of similar dimensions.     

Coherent rayleigh scattering

The spectrum of coherent scattering induced by electrostriction in gases has been analyzed in the previously unexplored, free-molecule limit by solving Boltzmann's equation with a periodic force due to the optical fields. Calculated and measured spectra of several gases at rarefied conditions are nearly Gaussian with widths approximately 10% wider than the spontaneous Rayleigh widths. Our results are the first spectrally resolved measurements of coherent Rayleigh scattering in the free-molecule limit, where the hydrodynamic analysis of stimulated Rayleigh-Brillouin scattering does not apply.     

Resonant rayleigh scattering from bilayer quantum Hall phases

We observe resonant Rayleigh scattering of light from quantum Hall bilayers at Landau level filling factor nu = 1. The effect arises below 1 Kelvin when electrons are in the incompressible quantum Hall phase with strong interlayer correlations. Marked changes in the Rayleigh scattering signal in response to application of an in-plane magnetic field indicate that the unexpected temperature dependence is linked to formation of a nonuniform electron fluid close to the phase transition towards the compressible state. These results demonstrate a new realm of study in which resonant Rayleigh scattering methods probe quantum phases of electrons in semiconductor heterostructures.     

Light scattering by dielectric particles with axial symmetry

A new method is suggested for solving the problem of scattering of a plane electromagnetic wave by dielectric particles with the axial symmetry. The method is based on the separation of fields into two parts: the axially symmetric part, which is independent of the angle of rotation, and the part that is not axially symmetric, which vanishes upon averaging over this angle. The scattering problem is solved separately for each of the parts. In the first case, scalar potentials related to the azimuthal components of electromagnetic fields are used, and in the second case, superpositions of the Debye potentials and vertical components of the Hertz vectors are used. The surface integral equations for these potentials are obtained. They are represented as expansions in the spherical wave functions. The infinite systems of linear algebraic equations are obtained for unknown expansion coefficients. Our calculations demonstrated the high efficiency of the new method.     

Lorentz force and the optical pulling of multiple rayleigh particles outside the dielectric cylindrical waveguides

The stimulating connection between the counter‐intuitive optical pulling effects and the Lorentz force has not been investigated in literature. This work demonstrates that multiple absorbing or non‐absorbing dielectric Rayleigh objects can be pulled locally with gradientless travelling waves outside a finite‐sized cylindrical nano or micro waveguide, if it is made up of a hollow core along with the cladding of at least two different dielectrics of appropriate refractive indices. Lorentz force analysis reveals that the bound surface charges of Rayleigh scatterer experience backward force, which overcomes the positive bulk force and ultimately results in the net pulling of the scatterer for several spatial regions outside the waveguide. Finally, in order to control the pulling of multiple Rayleigh particles based on scattering force and binding force, we have proposed a possible cylindrical coupler set‐up. This work may open a new window of optical pulling force due to the exclusion of conventional structured tractor beams along with the artificial exotic matters.     

The spin dependence of rayleigh scattering

The scattering amplitude for the scattering of circularly polarized KeV photons by a magnetized 3d transition metal is derived. In addition to the well-known form factor approximation a spin dependent term is found. It is smaller by a factor ω/mc ² (ω being the photon energy) and proportional to the spin magnetic form factor. Results for the degree of polarization are too small to explain recent experiments.     

Coherent microwave rayleigh scattering from resonance-enhanced multiphoton ionization in argon

Multiphoton ionization and electron recombination processes are studied in argon using coherent microwave Rayleigh scattering from a localized, resonance-enhanced multiphoton ionization produced plasma. A time dependent one-dimensional plasma dynamic model is developed to predict the time evolution of the microwave scattering from the plasma. Experimental results of the argon ionization spectrum and electron recombination rates are in good agreement with the model predictions.     

Resonant rayleigh scattering in semiconductor structures

Il Nuovo Cimento D - A detailed study of the relative role played by localized and/or propagating intermediate excitonic states in, resonant Rayleigh scattering (RRS) is presented for a large set...     

Spectral narrowing in coherent rayleigh scattering

Spectral narrowing of the coherent Rayleigh scattering line shape in a room temperature CO(2) gas (2.5 x 10(23) m(-3)) with intense fields in the 10(15) W m(-2) range is observed. The line shape saturates to a width of approximately half that observed at low pump intensities and indicates a transition from scattering primarily from untrapped molecules to that from both trapped and untrapped molecules that are localized by the deep (60 K) optical potentials produced by the pump beams. At higher densities (5 x 10(24) m(-3)), collisions between the trapped and untrapped molecules broaden the spectral profile.     

Light scattering by dielectric particles with axial symmetry: II

A new method is developed for calculating optical characteristics of axially symmetric particles. Electromagnetic fields are separated into two (axisymmetric and non-axisymmetric) parts. The light scattering problem is formed in the integral form and solved independently for each of the parts by using specially chosen scalar potentials. The potentials are expanded into series in spherical wave functions, and the expansion coefficients are calculated from solving the infinite systems of linear algebraic equations. The applicability of the proposed method for solving the problem of light scattering by Chebyshev particles, spheroids, and finite circular cylinders is briefly discussed, and some results of calculations performed for these particles are presented.     

Approximate formula for second-order rayleigh scattering from N acoustical scatterers

A model of second-order multiple scattering from N Rayleigh acoustical scatterers distribted at random throughout a volume V is analyzed, physically motivated approximations being used. The result is a simple expression for the angular distribution of the total second-order Rayleigh scattered flux that is analogous to the usual formula for first-order scattering from N independent scatterers.     

Measurement of thomson and rayleigh scattering in a preionizationZ-pinch

A 90° scattering experiment with a preionizationZ-pinch is described. The first part describes conventional measurements of the electron temperature and density (Thomson scattering). In the second part of the experiment Rayleigh scattering from excited hydrogen atoms was observed during very early phases of the discharge. This observation is possible because the Rayleigh scattering cross section of hydrogen atoms in the second and third quantum states is very large because of the small difference in the energy of the photons ofH _α (6563 Å) and the light of a ruby laser (6943 Å). Spectral resolution of this part of the scattered light yields a minimum value for the ion temperature.     

Angularly resolved backscattering of light from turbid suspensions of dielectric spheres

An analytic expression for the angular dependency of light backscattered from turbid suspensions of dielectric spheres that accounts for multiple-scattering effects is developed. The multiple-scattering model expresses backscattered light as a convolution of the phase function and a kernel representing the effects of forward scattering, multiplied by the optical thickness of the slab. Excellent agreement between Monte Carlo simulations and the analytic expressions is demonstrated for optical thicknesses of 0.1-4. The results are important for goniometric sizing measurements of biological cells and cellular organelles using elastically backscattered light.     

Raman scattering from gas-evaporated silicon small particles

Raman scattering measurements are reported on silicon small particles prepared by gas-evaporation technique. The crystalline structure is also observed for the sample having 70 A particles in average size. Four resolved component modes with Gaussian distribution function are identified with the three usual modes (LA, TO and allowed-TO) and a new surface mode. The surface mode of silicon particle, whose relative integrated intensity decrease with an increase of the particle size, is presented for the first time.     

Angle-resolved second-harmonic light scattering from colloidal particles

We report angle-resolved second-harmonic generation (SHG) measurements from suspensions of centrosymmetric micron-size polystyrene spheres with surface-adsorbed dye (malachite green). The second-harmonic scattering profiles differ qualitatively from linear light scattering profiles of the same particles. We investigated these radiation patterns using several polarization configurations and particle diameters. We introduce a simple Rayleigh-Gans-Debye model to account for the SHG scattering anisotropy. The model compares favorably with our experimental data. Our measurements suggest scattering anisotropy may be used to isolate particle nonlinear optics from other bulk nonlinear optical effects in suspension.