SEARCH · Search NASA

Results for “Interference microscopy”

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.

SourceResearch connectionFrom yearThrough year

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

At least 55 records · Page 3

All sources NASA NTRS DOE OSTI

DOE OSTI2024

2024 roadmap on magnetic microscopy techniques and their applications in materials science

Considering the growing interest in magnetic materials for unconventional computing, data storage, and sensor applications, there is active research not only on material synthesis but also characterisation of their properties. In addition to structural and integral magnetic characterisations, imaging of magnetisation patterns, current distributions and magnetic fields at nano- and microscale is of major importance to understand the material responses and qualify them for specific applications. In this roadmap, we aim to cover a broad portfolio of techniques to perform nano- and microscale magnetic imaging using superconducting quantum interference devices, spin centre and Hall effect magnetometries, scanning probe microscopies, x-ray- and electron-based methods as well as magnetooptics and nanoscale magnetic resonance imaging. The roadmap is aimed as a single access point of information for experts in the field as well as the young generation of students outlining prospects of the development of magnetic imaging technologies for the upcoming decade with a focus on physics, materials science, and chemistry of planar, three-dimensional and geometrically curved objects of different material classes including two-dimensional materials, complex oxides, semi-metals, multiferroics, skyrmions, antiferromagnets, frustrated magnets, magnetic molecules/nanoparticles, ionic conductors, superconductors, spintronic and spinorbitronic materials.

2D materials↗

DOE OSTI2025

Probing Surface Plasmon Dynamics in Periodic Nanostructures through Ultrafast Electron Microscopy

Surface plasmon polaritons (SPPs) can be manipulated to localize and guide light in subwavelength distances, enabling them to find applications in a wide range of areas, from sensing to quantum computing. Among several methods of SPP excitation, periodic arrays of nano- and microstructures are of particular interest, as they enable engineering SPP properties through structural parameters. Here, in this study, using the photon-induced near-field electron microscopy (PINEM) technique, we investigated the mode formation, coupling, interference, and decay of SPPs in square and hexagonal arrays of circular nanoholes under both visible and near-infrared excitation. Polarization-resolved analysis revealed the key factors governing SPP localization and interference patterns, showing that the periodicity and symmetry of the array primarily determine the SPP interference patterns and their orientation, while pump polarization mainly modulates their intensity. Time-resolved PINEM measurements demonstrated the spatial dependence of the SPP temporal characteristics. In addition, cathodoluminescence (CL) spectroscopy was employed to examine the intrinsic plasmonic characteristics of the structure. Finite difference time domain (FDTD) simulations showed strong agreement with both PINEM and CL measurements on the spatial and spectral behavior of SPPs. Understanding the spatiotemporal dynamics of SPPs on nanostructures beyond the diffraction limit is crucial for optimizing plasmonic structures for advanced photonic and quantum technologies.

Plasmonics↗

DOE OSTI2025

Anisotropic Response of Defect Bound States to the Magnetic Field in Epitaxial FeSn Films

Crystal defects, whether intrinsic or engineered, drive many fundamental phenomena and novel functionalities of quantum materials. Here, we report symmetry-breaking phenomena induced by Sn vacancy defects on the surface of epitaxial Kagome antiferromagnetic FeSn films using low-temperature scanning tunneling microscopy and spectroscopy. Near the single Sn vacancy, anisotropic quasiparticle interference patterns are observed in the differential conductance dI/dV maps, breaking the 6-fold rotational symmetry of the Kagome layer. Furthermore, the Sn vacancy defects induce bound states that exhibit anomalous Zeeman shift under an out-of-plane magnetic field, where the energy of the bound states moves linearly toward higher energy independent of the direction of the magnetic field. Under an in-plane magnetic field, the shift of the bound state energy also shows a 2-fold oscillating behavior as a function of the azimuth angle. These findings demonstrate defectenabled new functionalities in Kagome antiferromagnets for potential applications in nanoscale spintronic devices.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2024

Phase and contrast moiré signatures in two-dimensional cone beam interferometry

Neutron interferometry has played a distinctive role in fundamental science and characterization of materials. Moiré neutron interferometers are candidate next-generation instruments: they offer microscopy-like magnification of the signal, enabling direct camera recording of interference patterns across the full neutron wavelength spectrum. Here we demonstrate the extension of phase-grating moiré interferometry to two-dimensional geometries. Our fork-dislocation phase gratings reveal phase singularities in the moiré pattern, and we explore orthogonal moiré patterns with two-dimensional phase gratings. Our measurements of phase topologies and gravitationally induced phase shifts are in good agreement with theory. These techniques can be implemented in existing neutron instruments to advance interferometric analyses of emerging materials and precision measurements of fundamental constants. Published by the American Physical Society 2024

Sarenac, D. (ORCID:0000000185753367)↗

NASA NTRS1994

Measurements of striae in CR+ doped YAG laser crystals

Striations in Czochralski (CZ) grown crystals have been observed in materials such as GaAs, silicon, photorefractive crystals used for data storage, potassium titanyl phosphate crystals and LiNbO3. Several techniques have been used for investigating these defects including electron microscopy, laser scanning tomography, selective photoetching, X-ray diffuse scattering, interference orthoscopy, laser interferometry and micro-Fourier transform infrared spectroscopy mapping. A 2mm thick sample of the material to be investigated is illuminated with light that is absorbed and non-absorbed by the ion concentration to be observed. The back surface of the sample is focused onto a solid-state image detector and images of the input beam and absorbed (and diffracted) beams are captured at two wavelengths. The variation of the coefficient of absorption asa function of distance on the sample can be derived from these measurements. A Big Sky Software Beamcode system is used to capture and display images. Software has been written to convert the Beamcode data files to a format that can be imported into a spreadsheet program such as Quatro Pro. The spreadsheet is then used to manipulate and display data. A model of the intensity map of the striae collected by the imaging system has been proposed and a data analysis procedure derived. From this, the variability of the attenuation coefficient alpha can be generated. Preliminary results show that alpha may vary by a factor of four or five over distances of 100 mu m. Potential errors and problems have been discovered and additional experiments and improvements to the experimental setup are in progress and we must now show that the measurement techniques and data analysis procedures provide 'real' information. Striae are clearly visible at all wavelengths including white light. Their basic spatial frequency does not change radically, at least when changing from blue to green to white light. Further experimental and theoretical work can be done to improve the data collection techniques and to verify the data analysis procedures.

Cady, Fredrick M.↗

DOE OSTI2025

Correlated spin-wave generation and domain-wall oscillation in a topologically textured magnetic film

Spin waves, or magnons, are essential for next-generation energy-efficient spintronics and magnonics. Yet, visualizing spin-wave dynamics at nanoscale and microwave frequencies remains a formidable challenge due to the lack of spin-sensitive, time-resolved microscopy. Here, in this study, we report a breakthrough in imaging dipole-exchange spin waves in a ferromagnetic film owing to the development of laser-free ultrafast Lorentz electron microscopy, which is equipped with a microwave-mediated electron pulser for high spatiotemporal resolution. Using topological spin textures, we captured the emission, propagation, reflection and interference of spin waves from spin anti-vortices under radio-frequency excitations. Remarkably, we show that spin-wave generation is closely tied to the oscillatory motion of specific magnetic domain walls, providing the missing link between wave emission and wall dynamics near magnetic singularities. This work opens new possibilities in magnonics, offering a nanoscopic view of spin dynamics via transmission electron microscopy and enabling controlled excitation via radio-frequency fields for exploring non-equilibrium states in magnetic and multiferroic systems.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2024

Low-energy electronic structure in the unconventional charge-ordered state of ScV6Sn6

Abstract Kagome vanadates A V 3 Sb 5 display unusual low-temperature electronic properties including charge density waves (CDW), whose microscopic origin remains unsettled. Recently, CDW order has been discovered in a new material ScV 6 Sn 6 , providing an opportunity to explore whether the onset of CDW leads to unusual electronic properties. Here, we study this question using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM). The ARPES measurements show minimal changes to the electronic structure after the onset of CDW. However, STM quasiparticle interference (QPI) measurements show strong dispersing features related to the CDW ordering vectors. A plausible explanation is the presence of a strong momentum-dependent scattering potential peaked at the CDW wavevector, associated with the existence of competing CDW instabilities. Our STM results further indicate that the bands most affected by the CDW are near vHS, analogous to the case of A V 3 Sb 5 despite very different CDW wavevectors.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

NASA NTRS2000

Interferometry in the Extreme Ultraviolet and X-Ray

We report on demonstration of an x-ray interferometer that uses plane mirrors at grazing incidence to create interference fringes in the extreme ultraviolet and soft x-ray portions of the spectrum. X-ray interferometry has historically been implemented through narrow band, diffractive systems that split the wavefront. Our system, by using two separate optical channels to create interference from two areas of the wavefront, has broad band response and much higher efficiency. We discuss some applications of this technique to astronomy and microscopy including the possibility of eventually capturing a micro-arcsecond image of a black hole.

Cash, W.↗

DOE OSTI2025

Geometric control of magnetic domain morphology in electrodeposited Ni rich NiPt mesoscopic wires

In this paper, we study the electrodeposited Ni—Pt magnetic wires, exploring the mechanisms by which changes in geometry and composition influence the local magnetic structure. The samples were prepared by electrodeposition, their elemental composition was analyzed by energy dispersive X-ray spectroscopy, and phase analysis was carried out by an X-ray diffraction measurement. Magnetic force microscopy measurements, and magnetic force microscopy measurements in magnetic field were carried out to study the domain morphology of the prepared samples. Magnetization characteristics were measured via vibrating sample magnetometry mode of a superconducting quantum interference device. Here, the results were analyzed and compared with micromagnetic simulations. It is shown that a strong perpendicular magnetic anisotropy is responsible for the characteristic checkerboard-like surface magnetization patterns, which can be tuned by geometrical constriction and Ni content. Understanding these relationships provides insights into the design of magnetic materials with tailored properties for advanced applications, like magnetic sensors.

Binary alloy↗

DOE OSTI2025

Atomic-scale frustrated Josephson coupling and multicondensate visualization in FeSe

In a Josephson junction involving multiband superconductors, competition between interband and interjunction Josephson couplings gives rise to frustration and spatial disjunction of superfluid densities among superconducting condensates. Such frustrated coupling manifests as the quantum interference of Josephson currents from different tunnelling channels and becomes tunable if channel transparency can be varied. To explore these unconventional effects in the prototypical s ± -wave superconductor FeSe, we use atomic-resolution scanned Josephson tunnelling microscopy for condensate-resolved imaging and junction tuning—capabilities unattainable in macroscopic Josephson devices with fixed characteristics. We quantitatively demonstrate frustrated Josephson tunnelling by examining two tunnelling inequalities. The relative transparency of two parallel tunnelling pathways is found tunable, revealing a tendency towards a 0–π transition with decreasing scanned Josephson tunnelling microscopy junction resistance. Here, the simultaneous visualization of both superconducting condensates reveals anticorrelated superfluid modulations, highlighting the role of interband scattering. Our study establishes scanned Josephson tunnelling microscopy as a powerful tool enabling new research frontiers of multicondensate superconductivity.

Scanning probe microscopy↗

DOE OSTI2025

Dynamic molecular architecture of the synaptonemal complex

During meiosis, pairing between homologous chromosomes is stabilized by the assembly of the synaptonemal complex (SC). The SC ensures the formation of crossovers between homologous chromosomes and regulates their distribution. However, how the SC regulates crossover formation remains elusive. We isolated an unusual mutation in Caenorhabditis elegans that disrupts crossover interference but not SC assembly. This mutation alters the unique C terminal domain of an essential SC protein, SYP-4, a likely ortholog of the vertebrate SC protein SIX6OS1. We use three-dimensional stochastic optical reconstruction microscopy (3D-STORM) to interrogate the molecular architecture of the SC from wild-type and mutant C. elegans animals. Using a probabilistic mapping approach to analyze super-resolution image data, we detect changes in the organization of the synaptonemal complex in wild-type animals that coincide with crossover designation. We also found that our syp-4 mutant perturbs SC architecture. Our findings add to growing evidence that the SC is an active material whose molecular organization contributes to chromosome-wide crossover regulation.

59 BASIC BIOLOGICAL SCIENCES↗

NASA NTRS1990

Nature and origin of interstellar diamond from the Allende CV3 meteorite

Data and experimental evidence which support the contention that the C delta diamonds may result from grain-grain collisions in supernova shocks in the interstellar medium are presented. Fragments of the Allende CV3 chondrite were acid-treated. A whitish powder was obtained. For the Analytical Electron Microscopy (AEM) a small drop of ethanol suspension was transferred onto holey carbon support films on 3 mm EM grids. The AEM was performed on transmission-thin fragments of the material which overlay holes in the film, to eliminate interference from the substrate. Electron Spectroscopy for Chemical Analysis (ESCA) was performed on a large aliquot of C. Diamond was identified by selected area electron diffraction. Scanning Transmission Electron Microscope / Energy Dispersive X-ray (STEM-EDS) microanalyses of the C delta diamond, using a light-element detector, show that oxygen and possibly nitrogen are the only impurities consistently present. ESCA spectra from bulk C delta material confirm the presence of N at a level of 0.35 percent or less. Under UV irradiation a yellow-red fluorescence is observed, consistent with that of natural diamonds containing substitutional N. Electron Energy Loss Spectra (EELS) were recorded at 2 eV resolution from the C delta diamond, high pressure synthetic diamond, a diamond film produced in a low pressure plasma by chemical vapor deposition (CVD) on a heated silicon substrate (Roy, 1987), graphite, and amorphous arc sputtered carbon. Comparison of the carbon K edge shape and fine structure shows the Allende C delta phase to be largely diamond, but with a significant pre-edge absorption feature indicative of transitions of C 1s electrons into pi asterisk orbitals which are absent in the purely sp(3)-bonded diamond but present in graphite and amorphous carbon.

Blake, David↗

DOE OSTI2026

Metal alloy microparticle tagging of UO 2 fuel pellets for nuclear forensics

A tagging strategy for UO 2 fuel pellets will be discussed which involves the creation of alloyed metal microparticles that can be tuned to create a unique identification (“barcode”) indicating provenance of the pellets. These specialized markers would contain high temperature resistant materials, such as Ti, Mo, and Cr, in small quantities such that they do not interfere with the performance of the pellets but are recoverable by standard analytical techniques. The Amazemet rePowder ultrasonic atomization system was used to manufacture the microparticles, and sample pellets were fabricated and sintered containing these dopants. Various techniques, such as Scanning Electron Microscopy (SEM) and Electron Probe Microanalysis (EPMA), were used to evaluate these sample pellets to determine if particles (and their alloy compositions) were recoverable. Details on how the particles were manufactured and characterized will be detailed, as well as results from their incorporation into test pellets. Next steps will involve the scale of this technique using more conventional mass production methods, as well as the implementation of other alloys.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2025

Fast quantum interferometry at the nanometer and attosecond scales with energy-entangled photons

In classical optical interferometry, loss and background complicate achieving fast nanometer-resolution measurements with illumination at low light levels. Conversely, quantum two-photon interference is unaffected by loss and background, but nanometer-scale resolution is physically difficult to realize. As a solution, we enhance two-photon interference with highly nondegenerate energy entanglement featuring photon frequencies separated by 177 THz. We observe measurement resolution at the nanometer (attosecond) scale with only O(10 4 ) photon pairs, despite the presence of background and loss. Our nondestructive thickness measurement of a metallic thin film agrees with atomic force microscopy, which often achieves better resolution via destructive means. With contactless, nondestructive measurements in seconds or faster, our instrument enables metrological studies in optically challenging contexts where background, loss, or photosensitivity are factors.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2024

Harnessing Plasmonic Interference for Nanoscale Ultrafast Electron Sources

In this Letter we demonstrate the use of plasmonic focusing in conjunction with nonlinear photoemission to develop geometrically flat nanoscale electron sources with less than 40 pm-rad root mean squared (rms) normalized transverse emittance. Circularly polarized light is incident on a gold Archimedean spiral structure to generate surface-plasmon polaritons that interfere coherently at the center resulting in a 50 nm rms emission area. Furthermore, such a nanostructured flat surface enables simultaneous spatiotemporal confinement of emitted electrons at the nanometer and femtosecond level and can be used as an advanced electron source for high-repetition-rate ultrafast electron diffraction and microscopy experiments as well as the next generation of miniaturized particle accelerators.

43 PARTICLE ACCELERATORS↗

DOE OSTI2024

Defect‐Free Nanowelding of Bilayer SnSe Nanoplates

Nanowelding is a bottom‐up technique to create custom‐designed nanostructures and devices beyond the precision of lithographic methods. Here, a new technique is reported based on anisotropic lubricity at the van der Waals interface between monolayer and bilayer SnSe nanoplates and a graphene substrate to achieve precise control of the crystal orientation and the interface during the welding process. As‐grown SnSe monolayer and bilayer nanoplates are commensurate with graphene's armchair direction but lack commensuration along graphene's zigzag direction, resulting in a reduced friction along that direction and a rail‐like, 1D movement that permits joining nanoplates with high precision. This way, molecular beam epitaxially grown SnSe nanoplates of lateral sizes 30–100 nm are manipulated by the tip of a scanning tunneling microscope at room temperature. In situ annealing is applied afterward to weld contacting nanoplates without atomic defects at the interface. This technique can be generalized to any van der Waals interfaces with anisotropic lubricity and is highly promising for the construction of complex quantum devices, such as field effect transistors, quantum interference devices, lateral tunneling junctions, and solid‐state qubits.

2D ferroelectrics↗

DOE OSTI2025

Strain release through hydrogen bond–mediated layer twisting

Strain engineering, enabling the precise control over structure and functional properties, is a key strategy for the design of advanced materials. However, the mechanisms governing strain evolution and release at the nanoscale remain largely unexplored. In this study, we leverage in situ heating transmission electron microscopy and synchrotron x-ray spectroscopy to investigate the strain relaxation pathways of boehmite (γ-AlOOH) at 575 kelvin by revealing real-time structural dynamics. Through tracking the moiré pattern evolution, we identify distinct strain release mechanisms, including layer twisting, defect formation, and domain restructuring. Our neural network potential calculations reveal that energy fluctuations at small twist angles are dominated by an interference-like interaction modulation of hydrogen bonds between boehmite interlayers, with metastable twisted structures corresponding to local minima of the potential energy landscape. This work establishes a previously unidentified paradigm of two-dimensional layer twisting mediated by hydrogen bonding, offering insights into strain-driven transformation mechanisms, and thus may have broad implications for strain in material and earth sciences.

36 MATERIALS SCIENCE↗

NASA NTRS1984

Development of electrodes for the NASA iron/chromium

This program was directed primarily to the development of the negative (Cr3+/Cr2+) electrode for the NASA chromous/ferric Redox battery. The investigation of the effects of substrate processing and gold/lead catalyzation parameters on electrochemical performance were continued. In addition, the effects of reactant cross-mixing, acidity level, and temperature were examined for both Redox couples. Finally, the performance of optimized electrodes was tested in system hardware (1/3 square foot single cell). The major findings are discussed: (1) The recommended processing temperature for the carbon felt, as a substrate for the negative electrode, is 1650 to 1750 C, (2) The recommended gold catalyzation procedure is essentially the published NASA procedure (NASA TM-82724, Nov. 1981) based on deposition from aqueous methanol solution, with the imposition of a few controls such as temperature (25 C) and precatalyzation pH of the felt (7), (3) Experimental observations of the gold catalyzation process and subsequent electron microscopy indicate that the gold is deposited from the colloidal state, induced by contact of the solution with the carbon felt, (4) Electrodeposited lead appears to be present as a thin uniform layer over the entire surface of the carbon fibers, rather than an discrete particles, and (5) Cross-mixing of reactants (Fe-2+ in negative electrode solution or Cr-3+ in the positive electrode solution) did not appear to produce significant interference at either electrode.

Swette, L.↗