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Showing papers on "Scattering published in 1983"


Book
01 Jan 1983
TL;DR: In this paper, a Potpourri of Particles is used to describe surface modes in small Particles and the Angular Dependence of Scattering is shown to be a function of the size of the particles.
Abstract: BASIC THEORY. Electromagnetic Theory. Absorption and Scattering by an Arbitrary Particle. Absorption and Scattering by a Sphere. Particles Small Compared with the Wavelength. Rayleigh--Gans Theory. Geometrical Optics. A Potpourri of Particles. OPTICAL PROPERTIES OF BULK MATTER. Classical Theories of Optical Constants. Measured Optical Properties. OPTICAL PROPERTIES OF PARTICLES. Extinction. Surface Modes in Small Particles. Angular Dependence of Scattering. A Miscellany of Applications. Appendices. References. Index.

16,859 citations


Book
28 Feb 1983
TL;DR: Using classical and quantum methods with a strong emphasis on symmetry principles, the volume as discussed by the authors develops the theory of varied optical activity and related phenomena from the perspective of molecular scattering of polarized light.
Abstract: Ranging from the physics of elementary particles to the structure of viruses, the subject matter of this book stresses the importance of optical activity and chirality in modern science and will be of interest to a wide range of scientists. Using classical and quantum methods with a strong emphasis on symmetry principles, the volume develops the theory of varied optical activity and related phenomena from the perspective of molecular scattering of polarized light. First Edition Hb (1983): 0-521-24602-4

1,543 citations


Journal ArticleDOI
TL;DR: In this paper, light scattering of the linewidth and frequency shift of the optical phonon in silicon over the temperature range of 5-1400 K are presented. But they do not consider the four-phonon anharmonic processes.
Abstract: Systematic measurements by light scattering of the linewidth and frequency shift of the $\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}=0$ optical phonon in silicon over the temperature range of 5-1400 K are presented. Both the linewidth and frequency shift exhibit a quadratic dependence on temperature at high temperatures. This indicates the necessity of including terms in the phonon proper self-energy corresponding to four-phonon anharmonic processes.

1,208 citations


Journal ArticleDOI
TL;DR: In this paper, a number of unusual electromagnetic scattering effects for magnetic spheres are described, including complete polarization of scattered radiation in other directions, and asymmetry of forward scatter to backscatter.
Abstract: A number of unusual electromagnetic scattering effects for magnetic spheres are described. When ∊ = μ, the backscatter gain is zero; the scattered radiation is polarized in the same sense as the incident radiation. In the small-particle (or long-wavelength) limit, conditions are described for zero forward scatter, for complete polarization of scattered radiation in other directions, and for asymmetry of forward scatter to backscatter. The special case in the small-particle limit of m = 1, i.e., μ = 1/∊, provides interesting special instances of complete polarization and forward-scatter-to-backscatter asymmetry.

862 citations



Journal ArticleDOI
TL;DR: A Monte Carlo computer model has been used to predict the distribution of absorbed dose in homogeneous tissues of different absorption/scattering ratios, for illumination both by external light beams and via implanted optical fibers.
Abstract: A Monte Carlo computer model has been developed to study the propagation of light in tissues. Light attenuation is assumed to result from absorption and isotropic scattering. The model has been used to predict the distribution of absorbed dose in homogeneous tissues of different absorption/scattering ratios, for illumination both by external light beams and via implanted optical fibers. The photon flux into optical fibers placed in the tissue as detectors has also been investigated. The results are interpreted in relation to the use of visible light irradiation for photo radiation therapy.

688 citations


Journal ArticleDOI
TL;DR: In this paper, the formation and growth of soot particles in a coannular diffusion flame have been studied using a laser extinction/scattering technique for particle size measurement, and the results reveal that the flame can be broadly divided into two regions.

632 citations


Journal ArticleDOI
TL;DR: In this article, a general method of determining the structure and charge of globular ionic micelles, using neutron small-angle scattering, was presented, based in part on an analytic calculation of the interparticle correlations between monodisperse spherical mouselles.
Abstract: We present a general method of determining the structure and charge of globular ionic micelles, using neutron small-angle scattering. The micellar solutions may have any concentration within the micellar phase. The method is based in part on an analytic calculation of the interparticle correlations between monodisperse spherical micelles, and we discuss the theory in some detail to justify its application to polydisperse globular particles. Experimental results are presented for several cationic and anionic micellar systems.

615 citations


Journal ArticleDOI
TL;DR: Comparison of the results indicates the range of values of the scattering and absorption parameters where the computationally fast diffusion approach is applicable.
Abstract: To allow the determination of scattering and absorption parameters of a turbid material from reflection measurements the relation of these parameters to the reflection has been described by two theoretical approaches. One approach is based on the diffusion theory which has been extended to include anisotropic scattering. This results in a reflection formula in which the scattering and absorption are described by one parameter each. As a second more general approach a Monte Carlo model is applied. Comparison of the results indicates the range of values of the scattering and absorption parameters where the computationally fast diffusion approach is applicable.

498 citations


Journal ArticleDOI
TL;DR: In this paper, a Boltzmann-equation approach for the calculation of superconducting constrictions is presented, which allows for the inclusion of normal scattering as well as Andreev reflection processes in the constriction.
Abstract: A Boltzmann-equation approach for the calculation of the $I\ensuremath{-}V$ characteristics of superconducting constrictions is presented. This technique allows for the inclusion of normal scattering as well as Andreev reflection processes in the constriction. The computed $I\ensuremath{-}V$ characteristics exhibit subharmonic gap structure which varies strongly with scattering strength and temperature. For even small scattering strengths, the structure is found to persist to $T=0$, and its temperature dependence agrees qualitatively with experimental observations. In the limit of zero scattering, the technique is shown to be equivalent to the trajectory technique of Klapwijk, Blonder, and Tinkham.

370 citations


Journal ArticleDOI
TL;DR: In this article, a new model is proposed that attributes the scattering peak to interference between small ionic aggregates arranged with a liquid-like degree of order in the material, which is a variation on the model of a system of hard spheres in which the closest approach radius is larger than the scattering particle radius.
Abstract: The interpretation of the small-angle X-ray scattering (SAXS) data for ionomers has been the subject of considerable controversy in recent years. In this work, SAXS absolute scattered intensity data without slit-smearing effects have been obtained on a series of sulfonated polystyrene ionomers. The various microstructure models that have been proposed are evaluated by fitting calculated SAXS curves for each of the models to these data. It is shown that none of the existing models is entirely satisfactory. A new model is proposed that attributes the scattering peak to interference between small ionic aggregates arranged with a liquid-like degree of order in the material. The model is a variation on the model of a system of hard spheres in which the closest approach radius is larger than the scattering particle radius. The model provides an excellent fit to the data and is consistent with the sample compositions. The interpretation of other data regarding the dependence of the SAXS curve on swelling and stretching of the sample and the existence of two different ion environments is discussed. 49 references, 13 figures, 3 tables.


Journal ArticleDOI
TL;DR: In this article, it was shown that both bound and scattering states of a certain class of potentials are related to the unitary representations of certain groups, such as the Morse and Poschl-Teller potentials.

Journal ArticleDOI
TL;DR: In this article, a high frequency solution for scattering from a thin dielectric slab is developed, based on a modification of the uniform geometrical theory of diffraction solution for a haft-plane, with the intention of developing a model for a windshield of a small private aircraft.
Abstract: A high frequency solution for scattering from a thin dielectric slab is developed, based on a modification of the uniform geometrical theory of diffraction solution for a haft-plane, with the intention of developing a model for a windshield of a small private aircraft. Results of the theory are compared with experimental measurements and moment method calculations showing good agreement. Application of the solution is also addressed.

Journal ArticleDOI
TL;DR: It is shown that errors can occur in calculating the true rms surface roughness from actual TIS measurements; ways to correct these errors are discussed.
Abstract: Previously published vector equations describing angle-resolved scattering from single-layer- and multilayer-coated optics have been integrated numerically and analytically over all angles in the reflecting hemisphere to obtain numerical results and analytical expressions for total integrated scattering (TIS). The effects of correlation length, polarization, angle of incidence, roughness height distribution, scattered light missed by the collecting hemisphere, and roughness cross-correlation properties of the multilayer stack on the TIS expression are considered. Background material on TIS from optics coated with single opaque reflecting layers is given for completeness and comparison to corresponding multilayer TIS results. It is shown that errors can occur in calculating the true rms surface roughness from actual TIS measurements; ways to correct these errors are discussed.

Journal ArticleDOI
TL;DR: A high spectral resolution lidar technique to measure optical scattering properties of atmospheric aerosols is described, and Aerosol optical properties, such as the backscatter ratio, optical depth, extinctionCross section, scattering cross section, and theBackscatter phase function are derived.
Abstract: A high spectral resolution lidar technique to measure optical scattering properties of atmospheric aerosols is described. Light backscattered by the atmosphere from a narrowband optically pumped oscillator-amplifier dye laser is separated into its Doppler broadened molecular and elastically scattered aerosol components by a two-channel Fabry-Perot polyetalon interferometer. Aerosol optical properties, such as the backscatter ratio, optical depth, extinction cross section, scattering cross section, and the backscatter phase function, are derived from the two-channel measurements.

Journal ArticleDOI
TL;DR: In this paper, the authors measured the deepinelastic electron scattering from carbon up to and including the Δ-region at 36°, 60°, 90° and 145°.

Journal ArticleDOI
TL;DR: In this article, the authors report the results of some numerical experiments that bring out the lowpass characteristics of a purely elastic medium with a heterogeneous velocity structure and show that attenuation by intrinsic friction and scattering are approximately additive.
Abstract: We report the results of some numerical experiments that bring out the lowpass characteristics of a purely elastic medium with a heterogeneous velocity structure. Although the typical fluctuation is spatially confined within less than a wavelength, waves propagating over a sufficiently long path suffer major cumulative effects. We summarize the removal of high frequencies during transmission by a frequency-independent apparent Q, and show that attenuation by intrinsic friction and scattering are approximately additive. We propose some diagnostics that might help to distinguish the presence of velocity fluctuations and resultant scattering from the presence of anelasticity and true dissipation. When scattering dominates over intrinsic friction: (1) the coda of a transmitted wave contains relatively higher frequencies than the initial pulse; (2) the attenuation deduced from the power spectrum of the transmitted wave is greater than that deduced from the phase spectrum; (3) compressional and shear wave apparent Q's are approximately equal; and (4) estimates of apparent Q made from reflected coda vary with frequency, while estimates made from the transmitted waves do not. We also outline several topics in the theory of wave propagation that will be relevant in a satisfactory interpretation of short-period observations, if the amplitude of such signals is affected by scattering.

Journal ArticleDOI
TL;DR: In this article, the parameters defining the optical design for X-ray scattering and diffraction experiments with synchrotron radiation are derived and the various approaches are reviewed and a few selected examples illustrate the advantages of synchoretron radiation methods for various applications on poorly ordered systems.

Journal ArticleDOI
TL;DR: In this article, the spin-dependent asymmetries have been measured in deepinelastic scattering of longitudinally polarized electrons by long-polarized protons at a scattering angle of 10/sup 0/ and for incident energies of 16.2 and 22.7 GeV.
Abstract: Spin-dependent asymmetries have been measured in inclusive deep-inelastic scattering of longitudinally polarized electrons by longitudinally polarized protons. Data were obtained at a scattering angle of 10/sup 0/ and for incident energies of 16.2 and 22.7 GeV, which cover the kinematic range 0.18

Journal ArticleDOI
01 Jun 1983
TL;DR: In this article, an analytical/numerical technique is presented that provides a solution to the parabolic wave equation and allows for direct calculation of the received time-domain signal after propagation of a widebandwidth waveform through a turbulent ionized medium.
Abstract: An analytical/numerical technique is presented that provides a solution to the parabolic wave equation and allows for direct calculation of the received time-domain signal after propagation of a wide-bandwidth waveform through a turbulent ionized medium. The results are applicable to the case of satellite communication or to radar observation through a frequency-selective transionospheric propagation channel. A number of examples of the application of multiple phase-screen (MPS) techniques are given that enhance intuitive understanding of wave propagation. Numerical predictions of scattering through a striated barium cloud are compared to experimental observations. Good agreement is also shown between MPS calculations and theoretical results for cases in both weak and strong scattering regimes.

Journal ArticleDOI
TL;DR: In this article, the relationship between scattering data obtained from ultrasonic experiments, in which the waves are excited and detected in a finite measurement geometry, and unbounded medium, farfield scattering amplitudes is considered.
Abstract: The relationship between scattering data obtained from ultrasonic experiments, in which the waves are excited and detected in a finite measurement geometry, and unbounded medium, farfield scattering amplitudes is considered. For a scatterer in a single fluid medium, a Green’s function approach is used to develop an approximate, but absolute, relationship between these experimental and theoretical cases. Electromechanical reciprocity relationships are then employed to generalize to a two medium case in which the scatterer is located in an elastic solid which, along with the ultrasonic transducer, is immersed in a fluid medium. The case explicitly considered is one in which the incident waves are quasiplanar over the volume of the flaw and the scattering amplitudes are slowly varying over the range of angles subtended by the receiving transducer. Analytic approximations are developed for the absolute relationship of the received transducer signal to the unbounded medium scattering amplitudes, and formal exp...

Journal ArticleDOI
TL;DR: In this article, it is argued that observed concentration-dependent peaks in the x-ray and electron diffuse scattering intensities are due to parallel sheets of flat Fermi surface.
Abstract: On the basis of a new first-principles, electronic model for the forces driving clustering and short-range order in metallic alloys, it is argued that observed concentration-dependent peaks in the x-ray and electron diffuse scattering intensities are due to parallel sheets of flat Fermi surface. The positions of the peaks are directly related to the spanning vector k/sub 0/.

Journal ArticleDOI
TL;DR: In this paper, the reflection of light from an air-water interface is enhanced by dye containing monolayers in the spectral region of the dye absorption, and the intensity of reflected light depends linearly on the density of chromophores in the mixed monolayer.
Abstract: The reflection of light from an air–water interface is enhanced by dye containing monolayers in the spectral region of the dye absorption. The intensity of the reflected light depends linearly on the density of chromophores in the mixed monolayer. From the measurement of both absorption and reflection spectra of a dye containing monolayer the damping constant of coherent light scattering can be estimated. The value of the reflection measurement for the investigation of adsorption processes and the control of monolayer organization is demonstrated.

Journal ArticleDOI
TL;DR: In this paper, the Langer-Neal graph is translated into a transparent physical picture, which represents an interference experiment with conduction electrons split into pairs of waves interfering in the backscattering direction.
Abstract: The resistance of two-dimensional electron systems such as thin disordered films shows deviations from Boltzmann theory, which are caused by quantum corrections and are called "weak localization." Theoretically, weak localization is originated by the Langer-Neal graph in the Kubo formalism. In the present paper this graph is translated into a transparent physical picture. It represents an interference experiment with conduction electrons split into pairs of waves interfering in the backscattering direction. The intensity of the interference (integrated over the time) can be easily measured by the resistance of the film. A simple derivation for this quantum correction to the resistance is given. A magnetic field introduces a magnetic phase shift in the electronic wave function and suppresses the interference after a "flight" time proportional to $\frac{1}{H}$. Therefore, the application of a magnetic field allows observation of the fate of the electron as a function of time. Spin-orbit coupling rotates the spin of the electrons and yields an observable destructive interference, thereby demonstrating the change of sign of the electron-spin function by rotation. Magnetic impurities destroy the coherence of the phase. Therefore, with magnetoresistance measurements one can determine the inelastic lifetime, the spin-orbit coupling time, and the magnetic scattering time of the conduction electrons.

Journal ArticleDOI
TL;DR: In this paper, a relatively simple nonempirical formula for the imaginary part of the optical potential for electron scattering is derived from a quasifree-scattering model with Pauli blocking in which the target is treated as a free-electron gas.
Abstract: A relatively simple nonempirical formula for the imaginary part of the optical potential for electron scattering is derived from a quasifree-scattering model with Pauli blocking in which the target is treated as a free-electron gas. The resulting absorption potential is local and energy dependent and is a function of the electron density of the target. This model is tested for electron-helium and electron-neon scattering at 30--3000 eV. For these tests the real part of the potential is also approximated by a local expression, which is partitioned into static, exchange, and polarization terms. Reasonably good agreement with experimental data is obtained for the elastic integral, absorption, and elastic differential cross sections.

Journal ArticleDOI
TL;DR: In this article, the authors studied the Aharonov-Bohm effect from the viewpoint of scattering theory and proposed a scattering experiment that could distinguish between two different dynamics that have been considered in the literature.

Journal ArticleDOI
TL;DR: In this article, the authors present an analysis of the spin-wave spectrum of a semi-infinite stack of ferromagnetic films, each of which is separated by a gap filled by a nonmagnetic medium.
Abstract: We present an analysis of the spin-wave spectrum of a semi-infinite stack of ferromagnetic films, each of which is separated by a gap filled by a nonmagnetic medium. This is done within a formalism which includes the Zeeman and dipolar contributions to the spin-wave energy, with exchange omitted. We then calculate the spin-wave contribution to the Brillouin spectrum of such a system, in the backscattering geometry. The aim is to compare the spectrum for scattering from a sample with this geometry, with that from an isolated film. Two features unique to the stack appear in the spectrum. Each film, in isolation, possesses surface spin waves on its boundaries (Damon-Eshbach waves). In the layered geometry these interact to form a band of excitations of the array, which has nonvanishing component of wave vector normal to the stack. We find a feature in the spectrum associated with scattering from this band of modes; the position of the peak is controlled by dispersion introduced by interfilm interactions. Under certain conditions, the semi-infinite stack possesses a surface spin wave, whose eigenfunction is a linear superposition of individual film states, with amplitude that decays to zero as one moves down into the stack interior. This mode also produces a distinct feature in the light-scattering spectrum. These points are illustrated with a series of calculations of the spectrum, for parameters characteristic of layered ultrathin coherent structures.

Journal ArticleDOI
TL;DR: In this article, a general formalism was used to predict the enhancement in the radiated power for second-harmonic generation and Raman scattering from an electrochemically reformed silver surface.
Abstract: Emission from a variety of surface optical processes is significantly increased at interfaces with roughened noble metals. A general formalism, applicable to any optical process, is used to predict the enhancement in the radiated power for second-harmonic generation and Raman scattering from an electrochemically reformed silver surface. Experimental results for these enhancements at different wavelengths are reported. The intensity of the second-harmonic radiation can be understood strictly in terms of the strong macroscopic electric fields produced at the roughened surface by resonant structures. For Raman scattering, part of the enhancement also arises from microscopic local-field effects and the direct chemical interaction of the adsorbate and substrate. The surface-enhanced second-harmonic and Raman signals are studied as the silver sample undergoes oxidation and reduction in an electrolyte containing cyanide ions. The behavior of these two easily measurable probes is described and correlated with the system's surface chemistry.

Journal ArticleDOI
TL;DR: In this article, trajectories of the three lowest energy 2A′ potential surfaces are reported for Na(3p 2P) collisions with H2(v=0, low j) at 0.9 kcal/mol relative translational energy.
Abstract: Trajectory‐surface‐hopping calculations involving the three lowest‐energy 2A′ potential surfaces are reported for Na(3p 2P) collisions with H2(v=0, low j) at 0.9 kcal/mol relative translational energy. In addition to the total quenching cross section, we report distributions of final translational energy, final vibrational and rotational quantum numbers, internal energy, scattering angle, and collision time for the quenching collisions. We also report the opacity function, the correlation of scattering angle with impact parameter, and separate product translational spectra for the forward and backward scattered halves of the quenched ensemble. These results provide a detailed picture of the chemical dynamics of a typical quenching system proceeding through a quasibound intermediate configuration with large ionic character.