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All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

3⁢𝑄 magnetic order with spatially alternating spin scalar chirality in overdoped C⁢o 0.336⁢ Ta⁢S 2

C⁢o 𝑥 ⁢Ta⁢S 2 (𝑥≈1/3) exhibits a spontaneous Hall effect from spin texture in antiferromagnets, with a tetrahedral triple-Q (3Q) order and uniform spin scalar chirality. Upon Co overdoping (𝑥>1/3), it undergoes a shift in magnetic ordering vectors from 𝐐 m =(1/2, 0, 0) to (1/3, 0, 0). Interestingly, the spontaneous Hall effect disappeared in the overdoped regime, which was originally attributed to the loss of 3Q order. However, a question remains whether a new type of 3Q order can exist with alternating chirality in the overdoped regime. To address this, we investigated C⁢o 0.336⁢ Ta⁢S 2 using inelastic neutron scattering (INS), neutron diffraction, and optical dichroism, and found that INS data and spin-wave simulations support a 3Q order with alternating chirality. Moreover, neutron diffraction data show field-independent Bragg peaks, while linear dichroism detects no in-plane anisotropy, consistent with threefold rotation symmetry. Our data support the scenario of an alternating-chirality 3Q order in C⁢o 0.336 ⁢Ta⁢S 2 , canceling the spontaneous Hall effect. Furthermore, this study highlights a combined neutron-optical approach to identify complex spin textures.

Landau-Lifschitz-Gilbert equation↗
NASA NTRS1989

Current developments in optical engineering and commercial optics; Proceedings of the Meeting, San Diego, CA, Aug. 7-11, 1989

Various papers on current developments in optical engineering and commercial optics are presented. Individual topics addressed include: large optics fabrication technology drivers and new manufacturing techniques, new technology for beryllium mirror production, design examples of hybrid refractive-diffractive lenses, optical sensor designs for detecting cracks in optical materials, retroreflector field-of-view properties for open and solid cube corners, correction of misalignment-dependent aberrations of the HST via phase retrieval, basic radiometry review for seeker test set, radiation effects on visible optical elements, and nonlinear simulation of efficiency for large-orbit nonwiggler FELs.

Fischer, Robert E.↗
DOE OSTI2025

DONUT: physics-aware machine learning for real-time X-ray nanodiffraction analysis

Coherent X-ray scattering techniques are critical for investigating the fundamental structural properties of materials at the nanoscale. While advancements have made these experiments more accessible, real-time analysis remains a significant bottleneck, often hindered by artifacts and computational demands. In scanning X-ray nanodiffraction microscopy, which is widely used to spatially resolve structural heterogeneities, this challenge is compounded by the convolution of the divergent beam with the sample’s local structure. To address this, we introduce DONUT (Diffraction with Optics for Nanobeam by Unsupervised Training), a physics-aware neural network designed for the rapid and automated analysis of nanobeam diffraction data. By incorporating a differentiable geometric diffraction model directly into its architecture, DONUT learns to predict crystal lattice strain and orientation in real-time. Crucially, this is achieved without reliance on labeled datasets or pre-training, overcoming a fundamental limitation for supervised machine learning in X-ray science. We demonstrate experimentally that DONUT accurately extracts all features within the data over 200 times more efficiently than conventional fitting methods.

Materials science↗
DOE OSTI2025

DONUT: Physics-aware Machine Learning for Real-time X-ray Nanodiffraction Analysis

SF-25-088 Coherent X-ray scattering techniques are critical for investigating the fundamental structural properties of materials at the nanoscale. While advancements have made these experiments more accessible, real-time analysis remains a significant bottleneck, often hindered by artifacts and computational demands. In scanning X-ray nanodiffraction microscopy, which is widely used to spatially resolve structural heterogeneities, this challenge is compounded by the convolution of the divergent beam with the sample’s local structure. To address this, we introduce DONUT (Diffraction with Optics for Nanobeam by Unsupervised Training), a physics-aware neural network designed for the rapid and automated analysis of nanobeam diffraction data. By incorporating a differentiable geometric diffraction model directly into its architecture, DONUT learns to predict crystal lattice strain and orientation in real-time. Crucially, this is achieved without reliance on labeled datasets or pre-training, overcoming a fundamental limitation for supervised machine learning in X-ray science. We demonstrate experimentally that DONUT accurately extracts all features within the data over 200 times more efficiently than conventional fitting methods.

Zhou, Tao [Argonne National Laboratory (ANL), Argo↗
DOE OSTI2014

Polystyrene/MoS{sub 2}@oleylamine nanocomposites

The effects of adding different concentrations of MoS{sub 2}@oleylamine nano particles on the thermal and mechanical properties of polystyrene (PS) nanocomposites have been investigated. X-ray diffraction and optical microscopy were used to characterize the morphology of the resulting nanocomposites. The thermal stability of the nanocomposites has been characterized by thermogravimetric analysis. It has been found that the MoS{sub 2}@oleylamine nanoparticles have a good compatibility with the PS matrix forming homogeneous dispersion even at high concentrations. The PS/MoS{sub 2}@oleylamine nanocomposites showed enhanced thermal stability in comparison with neat polystyrene.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
NASA NTRS2001

Optical Amplifier Based Space Solar Power

The objective was to design a safe optical power beaming system for use in space. Research was focused on identification of strategies and structures that would enable achievement near diffraction limited optical beam quality, highly efficient electrical to optical conversion, and high average power in combination in a single system. Efforts centered on producing high efficiency, low mass of the overall system, low operating temperature, precision pointing and tracking capability, compatibility with useful satellite orbits, component and system reliability, and long component and system life in space. A system based on increasing the power handled by each individual module to an optimum and the number of modules in the complete structure was planned. We were concerned with identifying the most economical and rapid path to commercially viable safe space solar power.

Fork, Richard L.↗
DOE OSTI2014

Optical properties of Pr-doped BaY{sub 2}F{sub 8}

Crystalline samples of Pr-doped BaY{sub 2}F{sub 8} (BaYF) were prepared by zone melting technique. The pure phase obtained was identified by X-ray diffraction measurement. Optical absorption result was evaluated and it showed that the formation of the absorption bands can be connected to color centers generated by radiation in the matrix. Radioluminescence emission measurements after excitation by X-ray showed that the material exhibited components responsible for long lasting phosphorescence. Short decay times were also evaluated, the measurements showed a fast component around 70 ns associated to the 4f{sup 1}5d{sup 1} → 4f{sup 2} transition of the Pr{sup 3+} ion. The Thermoluminescence (TL) results indicate the presence of two trapping centers.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Massively parallel and universal approximation of nonlinear functions using diffractive processors

Nonlinear computation is essential for a wide range of information processing tasks, yet implementing nonlinear functions using optical systems remains a challenge due to the weak and power-intensive nature of optical nonlinearities. Overcoming this limitation without relying on nonlinear optical materials could unlock unprecedented opportunities for ultrafast and parallel optical computing systems. Here, we demonstrate that large-scale nonlinear computation can be performed using linear optics through optimized diffractive processors composed of passive phase-only surfaces. In this framework, the input variables of nonlinear functions are encoded into the phase of an optical wavefront—e.g., via a spatial light modulator (SLM)—and transformed by an optimized diffractive structure with spatially varying point-spread functions to yield output intensities that approximate a large set of unique nonlinear functions–all in parallel. We provide proof establishing that this architecture serves as a universal function approximator for an arbitrary set of bandlimited nonlinear functions, also covering wavelength-multiplexed nonlinear functions as well as multi-variate and complex-valued functions that are all-optically cascadable. Our analysis also indicates the successful approximation of typical nonlinear activation functions commonly used in neural networks, including the sigmoid, tanh, ReLU (rectified linear unit), and softplus. We numerically demonstrate the parallel computation of one million distinct nonlinear functions, accurately executed at wavelength-scale spatial density at the output of a diffractive optical processor. Furthermore, we experimentally validated this framework using in situ optical learning and approximated 35 unique nonlinear functions in a single shot using a compact setup consisting of an SLM and an image sensor. These results establish diffractive optical processors as a scalable platform for massively parallel universal nonlinear function approximation, paving the way for new capabilities in analog optical computing based on linear materials.

Rahman, Md Sadman Sakib [University of California,↗
DOE OSTI2015

Remote optical sensing on the nanometer scale with a bowtie aperture nano-antenna on a fiber tip of scanning near-field optical microscopy

Plasmonic nano-antennas have proven the outstanding ability of sensing chemical and physical processes down to the nanometer scale. Sensing is usually achieved within the highly confined optical fields generated resonantly by the nano-antennas, i.e., in contact to the nanostructures. In this paper, we demonstrate the sensing capability of nano-antennas to their larger scale environment, well beyond their plasmonic confinement volume, leading to the concept of “remote” (non contact) sensing on the nanometer scale. On the basis of a bowtie-aperture nano-antenna (BNA) integrated at the apex of a SNOM (Scanning Near-field Optical Microscopy) fiber tip, we introduce an ultra-compact, moveable, and background-free optical nanosensor for the remote sensing of a silicon surface (up to distance of 300 nm). Sensitivity of the BNA to its large scale environment is high enough to expect the monitoring and control of the spacing between the nano-antenna and a silicon surface with sub-nanometer accuracy. This work paves the way towards an alternative class of nanopositioning techniques, based on the monitoring of diffraction-free plasmon resonance, that are alternative to nanomechanical and diffraction-limited optical interference-based devices.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2016

Optical and x-ray photoelectron spectroscopy studies of α-Al{sub 2}O{sub 3}

α-Al{sub 2}O{sub 3} powder sample was synthesized at 550 °C via solution combustion synthesis (SCS) method using urea as an organic fuel. The sample was characterized by X-ray diffraction (XRD), Optical spectroscopy and X-ray photoelectron spectroscopy (XPS) without any further thermal treatment. XRD study reveals that the powder crystallized directly in the hexagons α-Al{sub 2}O{sub 3} phase. A band gap of 5.7 eV was estimated using diffuse reflectance spectra. For surface investigation X-ray photo electron spectroscopy (XPS) was carried out. The XPS survey scan study of α-Al{sub 2}O{sub 3} powder reveals that the sample is free from impurity. The core levels of Al-2s and O-1s are also reported.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Coating considerations for mirrors of CPV devices

One of the different optical concepts for concentrator devices is to place a focussing primary mirror behind a transparent front plate. In addition (also in case of Fresnel-diffractive main optics), further 'secondary' reflectors may be used further along the beam path. Such mirrors are usually implemented as coating stacks of a highly reflective metal - usually silver - and protective layers. The protective layers are preferably designed as reflection enhancing interference stack. The design of such protective layer stacks yields two difficulties, which are addressed in this paper: (a) vacuum coating of three-dimensional parts will result in a thickness distribution and the optical design of the stack should thus be tolerant to layer thickness variations, and (b) different places of the mirror will have different angle-of-incidence of the sunlight under operating conditions. As result, the layer stack has a different design at different places of the mirror.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1987

Backscatter analysis of dihedral corner reflectors using physical optics and the physical theory of diffraction

The backscatter cross-sections of dihedral corner reflectors in the azimuthal plane are presently determined by both physical optics (PO) and the physical theory of diffraction (PTD), yielding results for the vertical and horizontal polarizations. In the first analysis method used, geometrical optics is used in place of PO at initial reflections in order to maintain the planar character of the reflected wave and reduce the complexity of the analysis. In the second method, PO is used at almost every reflection in order to maximize the accuracy of the PTD solution at the expense of a rapid increase in complexity. Induced surface current densities and resulting cross section patterns are illustrated for the two methods.

Griesser, Timothy↗
DOE OSTI2021

Structural transitions of 4:1 methanol–ethanol mixture and silicone oil under high pressure

A 4:1 (volume ratio) methanol–ethanol (ME) mixture and silicone oil are two of the most widely used liquid pressure-transmitting media (PTM) in high-pressure studies. Their hydrostatic limits have been extensively studied using various methods; however, the evolution of the atomic structures associated with their emerging nonhydrostaticity remains unclear. Here, we monitor their structures as functions of pressure up to ∼30 GPa at room temperature using in situ high-pressure synchrotron x-ray diffraction (XRD), optical micro-Raman spectroscopy, and ruby fluorescence spectroscopy in a diamond anvil cell. No crystallization is observed for either PTM. The pressure dependence of the principal diffraction peak position and width indicates the existence of a glass transition in the 4:1 ME mixture at ∼12 GPa and in the silicone oil at ∼3 GPa, beyond which a pressure gradient emerges and grows quickly with pressure. There may be another liquid-to-liquid transition in the 4:1 ME mixture at ∼5 GPa and two more glass-to-glass transitions in the silicone oil at ∼10 GPa and ∼16 GPa. By contrast, Raman signals only show peak weakening and broadening for typical structural disordering, and Raman spectroscopy seems to be less sensitive than XRD in catching these structural transitions related to hydrostaticity variations in both PTM. These results uncover rich pressure-induced transitions in the two PTM and clarify their effects on hydrostaticity with direct structural evidence. The high-pressure XRD and Raman data on the two PTM obtained in this work could also be helpful in distinguishing between signals from samples and those from PTM in future high-pressure experiments.

Chen, Xiehang (ORCID:0000000168541506)↗
DOE OSTI2016

Synthesis and characterizations of (In{sub 0.90}Sn{sub 0.05}Ni{sub 0.05}){sub 2}O{sub 3} nanoparticles using solid state reaction method

ITO (In{sub 0.95}Sn{sub 0.05}){sub 2}O{sub 3} and Ni doped ITO (In{sub 0.90}Sn{sub 0.05}Ni{sub 0.05}){sub 2}O{sub 3} nanoparticles (NPs) were synthesized by solid state reaction method and subjected to study their structural, optical and magnetic properties. The NPs had a size distribution in the range of 40 nm and were identified as the bcc cubic In{sub 2}O{sub 3} by X-ray diffraction (XRD). Optical properties of the samples were studies using UV-Vis-NIR spectrophotometer. Magnetic measurements were carried out at room temperature and at 100 K using vibrating sample magnetometer and found that the ITO nanoparticles were ferromagnetic in nature at room temperature. The strength of the magnetization decreased in ITO nanoparticles when the magnetic measurements carried out at 100 K.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Phase Intergrowth and Structural Defects in Organic Metal Halide Ruddlesden–Popper Thin Films

Organic metal halide Ruddlesden–Popper phases combine the excellent optoelectronic properties of three-dimensional, bulk hybrid perovskites with superior material stability in ambient conditions. However, the thin film structure of these layered perovskites is still poorly understood, as phase purity is typically determined solely by specular X-ray diffraction. The thin film structure of these Ruddlesden–Popper phases was examined by increasingly local characterization techniques. It is difficult to assess the phase purity by purely bulk optical and diffraction measurements. From the comparison of grazing-incidence wide angle X-ray scattering (GIWAXS) patterns of cast films to expected scattering from single-crystal structures, significant in-plane disorder was observed. Spatially localized photoluminescence measurements show that films do not phase separate on the micrometer-scale. Selected area electron diffraction measurements show the intergrowth of different phases within the same thin film, consistent with previous observations seen in epitaxially-grown Ruddlesden–Popper complex oxides. Despite the presence of phase impurities that would typically be detrimental for device performance, fits to photothermal deflection spectroscopy measurements show relatively low Urbach energies of 33 meV for (C 4 H 9 NH 3 ) 2 (CH 3 NH 3 ) 2 Pb 3 I 10 and 32 meV for (C 4 H 9 NH 3 ) 2 (CH 3 NH 3 ) 3 Pb 4 I 13 , indicating that the electronic properties are insensitive to the phase impurities.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Determining the Spatial Profiles of Electron and Hole Concentration, Radiative and Non-Radiative Recombination Rate Near a Dislocation Defect by Combining Raman and Photoluminescence Imaging

For commonly utilized photoluminescence (PL) imaging, the spatial resolution is dictated by the carrier diffusion length rather than by that dictated by the optical system, such as diffraction limit. Here, we show that Raman imaging of the LO phonon-plasmon (LOPP) coupled mode can be used to recover the intrinsic spatial resolution of the optical system, as demonstrated by Raman imaging of defects in GaAs, achieving a 10-fold improvement in resolution. Furthermore, by combining Raman and PL imaging, we can independently determine the spatial profiles of the electron and hole density, radiative and non-radiative recombination rate near a dislocation defect, which has not been possible using other techniques.

14 SOLAR ENERGY↗
DOE OSTI2017

Interlaced zone plate optics for hard X-ray imaging in the 10 nm range

Multi-keV X-ray microscopy has been particularly successful in bridging the resolution gap between optical and electron microscopy. However, resolutions below 20 nm are still considered challenging, as high throughput direct imaging methods are limited by the availability of suitable optical elements. In order to bridge this gap, we present a new type of Fresnel zone plate lenses aimed at the sub-20 and the sub-10 nm resolution range. By extending the concept of double-sided zone plate stacking, we demonstrate the doubling of the effective line density and thus the resolution and provide large aperture, single- chip optical devices with 15 and 7 nm smallest zone widths. The detailed characterization of these lenses shows excellent optical properties with focal spots down to 7.8 nm. Furthermore, beyond wave front characterization, the zone plates also excel in typical imaging scenarios, verifying their resolution close to their diffraction limited optical performance.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗