Search NASA⌕ Search

SEARCH · Search NASA

Results for “diffraction”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

X-ray diffraction analysis of 4- and 4′-substituted C{sub n}H{sub 2n+1}O–C{sub 6}H{sub 3}(OH)–CH=N–C{sub 6}H{sub 4}–C{sub m}H{sub 2m+1} (n/m = 2/1 and 3/4) salicylideneanilines

X-ray diffraction study of two crystalline modifications of С{sub 2}Н{sub 5}O–C{sub 6}H{sub 3}(OН)–СН=N–C{sub 6}H{sub 4}–CH{sub 3} (1a, sp. gr. Р2{sub 1}/n, and 1b, sp. gr. С2/c) and С{sub 3}H{sub 7}O–C{sub 6}H{sub 3}(OН)–СН=N–C{sub 6}H{sub 4}–C{sub 4}H{sub 9} (2, sp. gr. Р2{sub 1}2{sub 1}2{sub 1}) has been performed. The 1a crystal structure contains two independent molecules. The molecules are conformationally nonrigid with respect to the mutual rotation of benzene rings; the dihedral angles between their planes are 29.19° and 26.00° in the independent molecules of 1a, 18.72° in the molecule of 1b, and 50.35° in the molecule of 2. The crystal packing of the compounds is discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Diffracted transition radiation of an ultra-high-energy relativistic electron beam in a thin single-crystal wafer

We consider diffracted transition radiation (DTR) emitted by high-energy relativistic electrons crossing a thin single-crystal wafer in the Laue geometry. The expression describing the DTR angular density is derived for the case where the electron path length in the target is much smaller than the X-ray wave extinction length in the crystal and the kinematic nature of this expression is demonstrated. It is shown that the DTR angular density in a thin target is proportional to the target thickness.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Superposition of M{sub 5}X{sub 5} superstructures and X-ray diffraction in TiO{sub 1.0} titanium monoxide

The interpretation of diffraction spectra of ordered high-temperature phases of solid solutions and strongly nonstoichiometric compounds is discussed. It has been shown that variations of the intensities of superstructure reflections, which cannot be explained within simple ordering models, can be due to the superposition of superstructures with different symmetries in the matrix of the basis crystal structure. Using an example of atom–vacancy ordering in TiO{sub 1.0} titanium monoxide, a model of the order–order transition state formed by the superposition of low-temperature monoclinic (space group A2/m (C2/m)) and high-temperature cubic (space group Pm3̅m) M{sub 5}X{sub 5} superstructures has been proposed. It has been shown that the transition state is thermodynamically equilibrium and should be implemented instead of the M{sub 5}X{sub 5} cubic superstructure. The transition state model can be considered as an M{sub (5–i)}X{sub (5–i)} superstructure (i = 1, 14/18, 11/18) with the monoclinic symmetry (space group P1m1).

36 MATERIALS SCIENCE↗
DOE OSTI2018

Dynamical Theory of X-Ray Diffraction for Restricted Beams: III. Analysis of Experimental Data for a Porous Crystal

Using the dynamical theory of X-ray diffraction for restricted beams, we have performed quantitative analysis of the structure of an InP(001) porous crystal layer on the basis of experimental data obtained by high-resolution X-ray diffractometry. The parameters of the porous crystal have been determined by simulating coherent and diffuse scattering. The influence of the instrumental function and dynamical effects on the results of investigation has been demonstrated.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

X-Ray Diffraction Analysis of Features of the Crystal Structure of GaN/Al{sub 0.32}Ga{sub 0.68}N HEMT-Heterostructures by the Williamson–Hall Method

The fitting of θ/2θ and ω peaks in X-ray diffraction curves is shown to be most accurate in the case of using an inverse fourth-degree polynomial or probability density function with Student’s distribution (Pearson type VII function). These functions describe well both the highest-intensity central part of the experimental peak and its low-intensity broadened base caused by X-ray diffuse scattering. The mean microdeformation ε and mean vertical domain size D are determined by the Williamson–Hall method for layers of GaN (ε ≈ 0.00006, D ≈ 200 nm) and Al{sub 0.32}Ga{sub 0.68}N (ε = 0.0032 ± 0.0005, D = 24 ± 7 nm). The D value obtained for the Al{sub 0.32}Ga{sub 0.68}N layer is most likely to result from the nominal thickness of this layer, which is 11 nm.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Microstructure of Si Crystals Subjected to Irradiation with High-Energy H{sup +} Ions and Heat Treatment by High-Resolution Three-Crystal X-Ray Diffraction and Transmission Electron Microscopy

The structural features of the formation of radiation defects in proton-implanted layers of silicon plates during their heat treatment have been studied. New data on the nature, the characteristics, and the microdefect concentration in Si crystals irradiated with protons with energies 100 + 200 + 300 keV with the total dose 2 × 10{sup 16} cm{sup –2} and the evolution of the defect structure during heat treatment have been obtained by high-resolution three-crystal X-ray diffraction and transmission electron microscopy over wide temperature range from 200 to 1100°C.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Electron Diffraction Study of Epitaxial Graphene Structure Grown upon SiC (0001) Thermal Destruction in Ar Atmosphere and in High Vacuum

We have studied the structure of epitaxial graphene obtained as a result of thermal desorption of the silicon carbide surface under conditions of vacuum synthesis and in Ar medium by reflection electron diffraction. As a result of the study, a significantly more uniform buffer layer coating of the SiC surface by epitaxial graphene has been found when forming in inert medium on the surface of 4H- and 6H-SiC(0001) polytypes compared with the synthesis of graphene in high vacuum. The quality of the coating has been shown to depend on the degree of perfection of the original single crystal.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Measurement Error of Interferometers with Diffraction Reference Wave

An experimental setup and results on aberration of sources of a reference spherical wave (SRSW) based on a single-mode optical fiber with a subwavelength output aperture obtained with the aid of an optical part of recording system (OPRS) are presented. SRSW and OPRS are developed for referenceless interferometer with diffraction reference wave. Methods for minimization of the measurement error are proposed. The SRSW and OPRS provide subnanometer measurement accuracy for optics. An increase in the measurement accuracy of the interferometer to a picometer level is discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Reciprocal-Space Maps of X-Ray Diffraction Intensity Distribution and Their Relation to the Dislocation Structure of Epitaxial Layers

X-ray diffraction (XRD) in asymmetric Bragg geometry was measured and XRD intensity distribution maps in the reciprocal space were constructed for GaN epitaxial layers with various degrees of structural perfection grown on c-sapphire substrates. It is established that equal-intensity lines (isolines) related to a regular system of perpendicular rectilinear threading dislocations are extended in a direction parallel to the surface. For a more chaotic distribution of dislocations with a large fraction of horizontal fragments, these isolines are rotated toward a direction perpendicular to the reciprocal lattice vector, although they still not attain a limiting position characteristic of the ideal mosaic crystal.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

A Crystal-Diffraction System Prototype for Measuring Neutron’s Charge: Thermal Protection Test and Vibration Measurements

A prototype system design for ultra-high-precision neutron spectrometry using diffraction in perfect crystals is described. Results of experimental verification of the temperature stability inside the setup are presented. Results of vibration spectrum measurements in working zone of the PF1b beam of ILL reactor (Grenoble, France), where the prototype setup will be arranged for experimental testing, are considered.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2023

Quantitative Scanning Transmission Electron Microscopy for Materials Science: Imaging, Diffraction, Spectroscopy, and Tomography

Scanning transmission electron microscopy (STEM) is one of the most powerful characterization tools in materials science research. Due to instrumentation developments such as highly coherent electron sources, aberration correctors, and direct electron detectors, STEM experiments can examine the structure and properties of materials at length scales of functional devices and materials down to single atoms. STEM encompasses a wide array of flexible operating modes, including imaging, diffraction, spectroscopy, and 3D tomography experiments. This review outlines many common STEM experimental methods with a focus on quantitative data analysis and simulation methods, especially those enabled by open source software. The hope is to introduce both classic and new experimental methods to materials scientists and summarize recent progress in STEM characterization. The review also discusses the strengths and weaknesses of the various STEM methodologies and briefly considers promising future directions for quantitative STEM research.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Diffraction imaging of light induced dynamics in xenon-doped helium nanodroplets

Time-resolved wide-angle coherent diffraction imaging of individual helium nanodroplets, doped with xenon and excited with an 800 nm NIR laser pulse. Raw and preprocessed pattern, together with useful metadata, are contained in HDF5 files. Every field in the H5 container comes with a description, under the field "description", and the actual data under the field "data". For further information about the dataset see the [ArXiv article](https://arxiv.org/abs/2205.04154 ) and Bruno Langbehn's [PhD thesis](https://depositonce.tu-berlin.de/handle/11303/13189).

FERMI FEL-1↗
DOE OSTI2022

Diffraction imaging of light induced dynamics in xenon-doped helium nanodroplets

Time-resolved wide-angle coherent diffraction imaging of individual helium nanodroplets, doped with xenon and excited with an 800 nm NIR laser pulse. Raw and preprocessed pattern, together with useful metadata, are contained in HDF5 files. Every field in the H5 container comes with a description, under the field "description", and the actual data under the field "data". For further information about the dataset see the [ArXiv article](https://arxiv.org/abs/2205.04154 ) and Bruno Langbehn's [PhD thesis](https://depositonce.tu-berlin.de/handle/11303/13189).

FERMI FEL-1↗
DOE OSTI2018

Utah FORGE: X-Ray Diffraction Data

This dataset contains X-ray diffraction (XRD) data taken from wells and outcrops as part of the DOE GTO supported Utah FORGE project located near Roosevelt Hot Springs. It contains an Excel spreadsheet with the XRD data, a text file with sample site names, types, and locations in UTM, Zone 12, NAD83 coordinates, and a GIS shapefile of the sample locations with attributes.

15 GEOTHERMAL ENERGY↗