Low-angle light scattering of ionotropic gels.
Low angle light scattering diffraction patterns of ionotropic gels, formed by Ca ion diffusion into polygalacturonate solution, indicating organized structures
Bettelheim, F. A.↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Theoretical and experimental investigation of the physics of crystalline surfaces Quarterly status report, 1 Aug. - 31 Oct. 1968
Particle densities, elastic and inelastic scattering, electron diffraction patterns, and adsorbate influence on surface structure and work function changes on crystalline surfaces
Bauer, E.↗
Iron meteorites - X-ray asterisms are not necessarily shock effects
X ray diffraction patterns, like patterns from kamacite in iron meteorites, formed by static deformation at low stresses
Fleischer, R. L.↗
LEED study of steps and facets on a Re surface
Low energy electron diffraction pattern from surface steps and facets resulting from recrystallization of Re single crystal
Feinstein, L. G.↗
Crystallography of some lunar plagioclases
Apollo 11 lunar rock plagioclases crystallography, obtaining single crystal X ray diffraction patterns by Buerger precession method
Appleman, D. E.↗
Optical mirror apparatus Patent
Highly stable optical mirror assembly optimizing image quality of light diffraction patterns
Tschunko, H. F. A.↗
Scintillation observations at Ancon and Jicamarca Observatories
Satellite scintillation and diffraction pattern scale size distribution from ionospheric irregularities
Guillen, A.↗
The diffraction of satellite signals by isolated ionospheric irregularities
Isolated ionospheric irregularities, describing refraction and diffraction pattern calculations for satellite signals
Titheridge, J. E.↗
Method and apparatus for eliminating coherent noise in a coherent energy imaging system without destroying spatial coherence
A method and apparatus for substantially eliminating noise in a coherent energy imaging system, and specifically in a light imaging system of the type having a coherent light source and at least one image lens disposed between an input signal plane and an output image plane are, discussed. The input signal plane is illuminated with the light source by rotating the lens about its optical axis. In this manner, the energy density of coherent noise diffraction patterns as produced by imperfections such as dust and/or bubbles on and/or in the lens is distributed over a ring-shaped area of the output image plane and reduced to a point wherein it can be ignored. The spatial filtering capability of the coherent imaging system is not affected by this noise elimination technique.
Shulman, A. R.↗
High voltage electron microscopy and electron diffraction of pyroxenes in type B lunar samples from Apollo 11
Lunar pyroxene 10044 specimens cleaved and sectioned by diamond knife ultramicrotomy were examined by standard (75 to 100 kV) and high voltage (200 kV) electron microscopy and diffraction. Salient findings based on evaluation of 2000 plates show uniform 300 to 600 A-wide bands, probably corresponding to single crystal domains, with lattice spacings of 2. A High resolution bright and dark field images of iron-rich and magnesium-rich crystals were compared with corresponding electron diffraction patterns. Possible relations of observed structures to magnetic domains were considered.
Fernandez-Moran, H.↗
Evidence of crystal structure in some sputtered MoS2 films.
Electron diffraction patterns and electron micrographs of molybdenum disulfide films sputtered on single-NaCl-crystal and electropolished-aluminum substrates are presented as evidence that crystalline MoS2 films can be sputtered onto various substrates in thicknesses up to 2 microns. Applied to Falex test pins and V-blocks, some of these films exhibited a wear life as long as 65 minutes at 1000 lb jaw load.
Lavik, M. T.↗
Very High-Frequency (VHF) ionospheric scintillation fading measurements at Lima, Peru
During the spring equinox of 1970, scintillating signals at VHF (136.4 MHz) were observed at Lima, Peru. The transmission originated from ATS 3 and was observed through a pair of antennas spaced 1200 feet apart on an east-west baseline. The empirical data were digitized, reduced, and analyzed. The results include amplitude probability density and distribution functions, time autocorrelation functions, cross correlation functions for the spaced antennas, and appropriate spectral density functions. Results show estimates of the statistics of the ground diffraction pattern to gain insight into gross ionospheric irregularity size, and irregularity velocity in the antenna planes.
Blank, H. A.↗
Influence of various surface pretreatments on adherence of sputtered molybdenum disulfide to silver, gold, copper, and bronze
Solid film lubricants of radio frequency sputtered molybdenum disulfide (MoS2) were applied to silver, gold, copper, and bronze surfaces that had various pretreatments (mechanical polishing, sputter etching, oxidation, and sulfurization). Optical and electron transmission micrographs and electron diffraction patterns were used to interpret the film formation characteristics and to evaluate the sputtering conditions in regard to the film and substrate compatibility. Sputtered MoS2 films flaked and peeled on silver, copper, and bronze surfaces except when the surfaces had been specially oxidized. The flaking and peeling was a result of sulfide compound formation and the corresponding grain growth of the sulfide film. Sputtered MoS2 films showed no peeling and flaking on gold surfaces regardless of surface pretreatment.
Spalvins, T.↗
Remote analysis of planetary soils: X-ray diffractometer development
A system is described suitable for remote low power mineralogical analysis of lunar, planetary, or asteroid soils. It includes an X-ray diffractometer, fluorescence spectrometer, and sample preparation system. A one Curie Fe-55 source provides a monochromatic X-ray beam of 5.9 keV. Seeman-Bohlin or focusing geometry is employed in the camera, allowing peak detection to proceed simultaneously at all angles and obviating the need for moving parts. The detector system is an array of 500-600 proportional counters with a wire-spacing of 1 mm. An electronics unit comprising preamplifier, postamplifier, window discriminators, and storage flipflops requiring only 3.5 milliwatts was designed and tested. Total instrument power is less than 5 watts. Powder diffraction patterns using a flat breadboard multiwire counter were recorded.
Gregory, J. C.↗
Glancing incidence telescopes for space astronomy
A technique for determining the state of polarization of a light source by evaluating its image at the focus of a glancing telescope is reported. An analysis of the central disc of the diffraction image reveals if the light source is polarized, the plane of polarization, and the degree of polarization. When polarized light is incident at the aperture of a diffraction limited glancing telescope, the central disc of the diffraction pattern takes on an elliptical configuration. This ellipticity is caused by the tendency of the electric vector component in the plane of incidence to be absorbed by the reflecting material. As the state of polarization goes from plane polarized to decreasing degrees of elliptically polarized light, the ellipticity of the central disc goes from a maximum at plane polarization to zero at circular polarization. These curves give a direct relationship between the degree of polarization of a light source and the ellipticity of the central disc for this particular telescope, independent of the light source wavelength.
Alonso, J., Jr.↗
Electron petrography of Apollo sample 14310.
Thin sections prepared from Apollo sample 14310 have been examined with 100-kV transmission electron microscopy. The sample is composed principally of anorthite and pyroxene. The anorthites fall into two categories. The transitional anorthites that show the characteristic 'c' type diffraction maxima are characterized by very fine antiphase domain structures and some fine twinning. The body-centered anorthites that show no 'c' reflections are characterized by an absence of fine twinning and a less well-defined antiphase domain structure. Although both orthopyroxene and clinopyroxenes are reported in sample 14310, only clinopyroxenes were observed in this study and all show exsolution structures. The augite exsolved in pigeonite commonly is along lamellae parallel to (100), although (001) lamellae are also present. This unusual orientation was verified by diffraction patterns. The pigeonite commonly shows antiphase domains, attributed to stacking errors when the sample inverted from its high-temperature disordered form. In augite as the host phase, the pigeonite lamellae contain very complex structures including antiphase domains.
Smith, D. K.↗
Josephson junction interference grating.
The maximum current through multiple Josephson structures as a function of applied magnetic field is presented. Particular emphasis is placed on the Josephson penetration depth effects and geometrical considerations. The symmetrical and asymmetrical current feed two-, three-, four-, and five-junction gratings are analyzed and discussed. The Josephson penetration depth is shown to control the amplitude of the interference and diffraction patterns of the interference grating. In addition the interior-junction-length/interference-loop-area product is shown to control the operating mode of the interference grating. The dependence of the magnetic field sensitivity and interference pattern amplitude on the number of junctions is discussed.
Stuehm, D. L.↗
Automated thematic mapping and change detection of ERTS-A images
The author has identified the following significant results. For the recognition of terrain types, spatial signatures are developed from the diffraction patterns of small areas of ERTS-1 images. This knowledge is exploited for the measurements of a small number of meaningful spatial features from the digital Fourier transforms of ERTS-1 image cells containing 32 x 32 picture elements. Using these spatial features and a heuristic algorithm, the terrain types in the vicinity of Phoenix, Arizona were recognized by the computer with a high accuracy. Then, the spatial features were combined with spectral features and using the maximum likelihood criterion the recognition accuracy of terrain types increased substantially. It was determined that the recognition accuracy with the maximum likelihood criterion depends on the statistics of the feature vectors. Nonlinear transformations of the feature vectors are required so that the terrain class statistics become approximately Gaussian. It was also determined that for a given geographic area the statistics of the classes remain invariable for a period of a month but vary substantially between seasons.
Gramenopoulos, N.↗