Rare gas scattering from molten metals examined with classical scattering theory

André Muis; J. R. Manson

doi:10.1063/1.474517

The interaction of rare gas atoms with metal surfaces: a scattering theory approach

Surface Science ◽

10.1016/0039-6028(92)90982-c ◽

1992 ◽

Vol 268 (1-3) ◽

pp. 432-456 ◽

Cited By ~ 53

Author(s):

A. Chizmeshya ◽

E. Zaremba

Keyword(s):

Scattering Theory ◽

Metal Surfaces ◽

Rare Gas ◽

Theory Approach ◽

Rare Gas Atoms

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Macroscopic theory of dielectric solids. II. The theory of Brillouin scattering from rare gas crystals

Canadian Journal of Physics ◽

10.1139/p78-027 ◽

1978 ◽

Vol 56 (2) ◽

pp. 199-215 ◽

Cited By ~ 18

Author(s):

J. E. Sipe

Keyword(s):

Local Field ◽

Scattering Theory ◽

Short Range ◽

Brillouin Scattering ◽

Microscopic Model ◽

Rare Gas ◽

Dielectric Tensor ◽

Macroscopic Theory ◽

Effective Electric Field ◽

Dielectric Solids

We extend the macroscopic theory of dielectric solids to include the description of the Brillouin scattering of light by deriving expressions for the dielectric constant in the absence of strains, and for the Pockels elasto-optic coefficients, from a microscopic model appropriate for the rare gas crystals. The constituent atoms are regarded as polarizable particles coupled by the dipole–dipole interaction, which we treat by introducing the usual microscopic effective electric field, and by the short-range higher multipole and Vander Waals interactions, which are included in the microscopic model by associating with each atom an effective polarizability that depends on the distance between the atom and its nearest neighbors. We define the macroscopic fields by space averaging over volume elements of linear dimensions Δ satisfying a [Formula: see text], where a is the interatomic spacing and λ the wavelength in vacuo; using a new theorem relating the microscopic effective electric field and macroscopic electric and polarization fields, we are able to derive a constitutive relation, involving the strain tensor, from our microscopic model. While the largest contribution to the Pockels coefficients appearing in this relation is due to variations in the dielectric tensor that result from deviations of the macroscopic density from its value in the absence of strains, we find that two other contributions appear because strain fields affect the dielectric tensor by changing both the local field and the values of the effective polarizabilities. If the short-range interactions are neglected, our theory leads to the same ratios of Pockels coefficients obtained from the microscopic scattering theory of Werthamer (when an error in that theory is corrected), but the values of the Pockels coefficients we obtain contain a local field correction, which the microscopic scattering theory does not take into account. The contribution of the short-range interactions to the Pockels coefficients is estimated by obtaining values of the effective polarizabilities from calculations of the polarizabilities of pairs of rare-gas atoms; we find that the contribution is non-negligible and thus demonstrate that new information on these short-range interactions can be obtained from the results of Brillouin scattering experiments.

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Southern Hemisphere Seti Survey: Five Years of Project Meta II

International Astronomical Union Colloquium ◽

10.1017/s0252921100015153 ◽

1997 ◽

Vol 161 ◽

pp. 611-621

Author(s):

Guillermo A. Lemarchand ◽

Fernando R. Colomb ◽

E. Eduardo Hurrell ◽

Juan Carlos Olalde

Keyword(s):

Southern Hemisphere ◽

Scattering Theory ◽

Galactic Plane ◽

Narrow Band ◽

Neutral Hydrogen ◽

Sky Survey ◽

Inertial Frames ◽

Interstellar Scattering ◽

Extraterrestrial Origin ◽

Spectral Channels

AbstractProject META II, a full sky survey for artificial narrow-band signals, has been conducted from one of the two 30-m radiotelescopes of the Instituto Argentino de Radioastronomía (IAR). The search was performed near the 1420 Mhz line of neutral hydrogen, using a 8.4 million channels Fourier spectrometer of 0.05 Hz resolution and 400 kHz instantaneous bandwidth. The observing frequency was corrected both for motions with respect to three astronomical inertial frames, and for the effect of Earths rotation, which provides a characteristic changing signature for narrow-band signals of extraterrestrial origin. Among the 2 × 1013spectral channels analyzed, 29 extra-statistical narrow-band events were found, exceeding the average threshold of 1.7 × 10−23Wm−2. The strongest signals that survive culling for terrestrial interference lie in or near the galactic plane. A description of the project META II observing scheme and results is made as well as the possible interpretation of the results using the Cordes-Lazio-Sagan model based in interstellar scattering theory.

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Dynamical Scattering in Electron Diffraction of wet Protein Crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600000167 ◽

1980 ◽

Vol 38 ◽

pp. 42-43

Author(s):

B. B. Chang ◽

D. F. Parsons

Keyword(s):

Electron Diffraction ◽

Scattering Theory ◽

Protein Crystals ◽

Electron Diffraction Data ◽

Specimen Thickness ◽

Major Question ◽

X Ray ◽

Scattering Effects ◽

Diffraction Patterns ◽

Acceleration Voltage

The significance of dynamical scattering effects remains the major question in the structural analysis by electron diffraction of protein crystals preserved in the hydrated state. In the few cases (single layers of purple membrane and 400-600 Å thick catalase crystals examined at 100 kV acceleration voltage) where electron-diffraction patterns were used quantitatively, dynamical scattering effects were considered unimportant on the basis of a comparison with x-ray intensities. The kinematical treatment is usually justified by the thinness of the crystal. A theoretical investigation by Ho et al. using Cowley-Moodie multislice formulation of dynamical scattering theory and cytochrome b5as the test object2 suggests that kinematical analysis of electron diffraction data with 100-keV electrons would not likely be valid for specimen thickness of 300 Å or more. We have chosen to work with electron diffraction patterns obtained from actual wet protein crystals (rat hemoglobin crystals of thickness range 1000 to 2500 Å) at 200 and 1000 kV and to analyze these for dynamical effects.

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