Transmission and reflection of a surface wave plate mode through a transverse boundary separating two isotropic media

The methods of two dimensional model seismology were used to investigate the phenomena occurring when a Rayleigh wave is incident upon a corner whose angle is comprised between 0° and 180°. The wave bends its path only for angles between 130° and 180°. For smaller angles large and abrupt variations in reflection and transmission occur; the wave travels to the extremity of the corner and never “cuts corners”; only about 50 percent of the energy of the indicent surface wave is preserved as such, the rest goes into body waves; for a 90° corner the proportion is about 23 percent in P and 26 percent in S, with sharply preferential angles of incidence. The percentages given were found for a “plate Poisson’s ratio” of 0.17.

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Experimental observation of surface wave propagation for a transversely isotropic medium

Geophysics ◽

10.1190/1.1443745 ◽

1995 ◽

Vol 60 (1) ◽

pp. 185-190 ◽

Cited By ~ 10

Author(s):

Chih‐Hsiung Chang ◽

Gerald H. F. Gardner ◽

John A. McDonald

Keyword(s):

Wave Propagation ◽

Surface Wave ◽

Surface Waves ◽

Transversely Isotropic ◽

Insulation Material ◽

Velocity Anisotropy ◽

Vertical Seismic Profiling ◽

Surface Wave Propagation ◽

Transversely Isotropic Media ◽

Isotropic Media

Velocity anisotropy of surface‐wave propagation in a transversely isotropic solid has been observed in a laboratory study. In this study, Phenolite™, an electrical insulation material, was used as the transversely isotropic media (TIM), and a vertical seismic profiling (VSP) geometry was used to record seismic arrivals and to separate surface waves from shear waves. Results show that surface waves that propagate with different velocities exist at certain directions.

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Atomic-level imaging of the surface structure of Ag2O

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100113160 ◽

1984 ◽

Vol 42 ◽

pp. 656-657

Author(s):

William Krakow

Keyword(s):

High Vacuum ◽

Atomic Level ◽

Ultra High Vacuum ◽

Research Groups ◽

Resolution Electron ◽

Surface Reconstructions ◽

Order Of Magnitude ◽

High Resolution Electron Microscope ◽

Saturated Structure ◽

Transmission And Reflection

In recent years electron microscopy has been used to image surfaces in both the transmission and reflection modes by many research groups. Some of this work has been performed under ultra high vacuum conditions (UHV) and apparent surface reconstructions observed. The level of resolution generally has been at least an order of magnitude worse than is necessary to visualize atoms directly and therefore the detailed atomic rearrangements of the surface are not known. The present author has achieved atomic level resolution under normal vacuum conditions of various Au surfaces. Unfortunately these samples were exposed to atmosphere and could not be cleaned in a standard high resolution electron microscope. The result obtained surfaces which were impurity stabilized and reveal the bulk lattice (1x1) type surface structures also encountered by other surface physics techniques under impure or overlayer contaminant conditions. It was therefore decided to study a system where exposure to air was unimportant by using a oxygen saturated structure, Ag2O, and seeking to find surface reconstructions, which will now be described.

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Exit-surface wave reconstruction using a focal series

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100129577 ◽

1992 ◽

Vol 50 (2) ◽

pp. 988-989

Author(s):

W.J. de Ruijter ◽

M.R. McCartney ◽

David J. Smith ◽

J.K. Weiss

Keyword(s):

Surface Wave ◽

Spherical Aberration ◽

Data Extraction ◽

High Sensitivity ◽

Geometric Distortion ◽

Variation Method ◽

Objective Lens ◽

Immediate Reconstruction ◽

Exit Surface ◽

Electron Microscopes

Further advances in resolution enhancement of transmission electron microscopes can be expected from digital processing of image data recorded with slow-scan CCD cameras. Image recording with these new cameras is essential because of their high sensitivity, extreme linearity and negligible geometric distortion. Furthermore, digital image acquisition allows for on-line processing which yields virtually immediate reconstruction results. At present, the most promising techniques for exit-surface wave reconstruction are electron holography and the recently proposed focal variation method. The latter method is based on image processing applied to a series of images recorded at equally spaced defocus.Exit-surface wave reconstruction using the focal variation method as proposed by Van Dyck and Op de Beeck proceeds in two stages. First, the complex image wave is retrieved by data extraction from a parabola situated in three-dimensional Fourier space. Then the objective lens spherical aberration, astigmatism and defocus are corrected by simply dividing the image wave by the wave aberration function calculated with the appropriate objective lens aberration coefficients which yields the exit-surface wave.

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