Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session W45: Advanced Coherent X-ray SourcesFocus
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Sponsoring Units: GIMS Chair: Youli Li, University of California, Santa Barbara Room: Room 315 |
Thursday, March 9, 2023 3:00PM - 3:36PM |
W45.00001: Quantifying Nanoscale Chemical Heterogeneity with Coherent X-ray Microscopy Invited Speaker: David A Shapiro The very high brightness of synchrotron x-ray sources has enabled the continued development of coherent x-ray microscopy which is a powerful tool for the analysis of chemical and magnetic states in nano-materials. Scanning microscopes, which achieve the highest spatial resolution when using coherent light, are best suited to exploit the coherence gains expected from the new generation of diffraction limited synchrotron sources. High resolution, currently considered to be below 10 nanometers, can be achieved either with high numerical aperture x-ray optics or via computational imaging methods which reconstruct the image from coherent x-ray scattering patterns. The latter method replaces the need for high numerical aperture optics, which may be inefficient or suffer from very short working distances, with high speed imaging detectors and computational complexity. The advent of high speed x-ray pixel detectors and phase retrieval based reconstruction algorithms has led to the broad development of x-ray ptychography as a robust means of achieving high spatial resolution in an x-ray microscope. The ALS, as a soft x-ray synchrotron source, has pioneered the application of x-ray ptychography to the quantitative analysis of chemical phases in nanomaterials. I will present the design and performance of our newest x-ray microscope and data analysis infrastructure which can achieve a spatial resolution below 10 nm. I will also review several important scientific applications including redox reactions in energy storage materials and crystal orientation in biominerals. As a national scientific user facility, the ALS makes its experimental systems freely available to the general scientific community for open scientific research. |
Thursday, March 9, 2023 3:36PM - 3:48PM |
W45.00002: Dark field x-ray microscopy for mesoscale phenomena in ordered quantum, structural, and functional materials at modern light sources Zahir Islam, Elliot S Kisiel, Jayden C Plumb, Omar Shohoud, Ishwor Poudyal, Zhan Zhang, Siddarth Maddali, Stephan O Hruszkewycz Single-crystal diffraction reveals an ‘average’ view of ordered materials; in contrast, dark field x-ray microscopy (DFXM) provides real-space images of mesoscale inhomogeneities that encode spatial information on a Bragg, or a super-lattice (e.g. charge-density wave, magnetic order) peak. In DFXM, a lens magnifies a Bragg peak exiting a sample to form an image. DFXM carried out concurrently with in situ multi-modal measurements can shed light on underlying correlations of materials properties to mesoscale features. Some examples are presented to illustrate the potency of DFXM and introduce cryogenic and associated instrumentation. |
Thursday, March 9, 2023 3:48PM - 4:00PM |
W45.00003: How big can we go small? DLSRs and nanoimaging of macro objects Chris J Jacobsen Diffraction-limited storage rings (DLSRs) are expected to provide an increase of two orders of magnitude in quasi-time-continuous coherent x-ray flux. At present, nanoscale coherent x-ray imaging is done on samples no larger than a few micrometers across. However, sub-20 nanometer spatial resolution has been obtained in images of circuit layers on un-thinned silicon wafers, highlighting the penetration power of X rays. Can we upscale nanoscale [1] x-ray imaging to the study of millimeter-sized (or larger) samples? This would enable studies of tissues and materials where the full macroscopic functional context could be provided for the understanding of nanoscale features or processes. This talk considers the challenges in reaching towards that goal (including imaging beyond the depth-of-focus limit) and provides estimates of the imaging time for two example sample types: biological specimens, and integrated circuit features. Calculations suggest that the imaging of nanoscale features in millimeter- or even centimeter-sized specimens is achievable within somewhat practical time limits. To reach this potential, key limitations in experimental hardware and in computational reconstruction methods are noted. |
Thursday, March 9, 2023 4:00PM - 4:12PM |
W45.00004: Data-driven discovery of dynamics from time-resolved coherent X-ray scattering Nina Andrejevic, Mathew Cherukara, Maria K Chan, Tao Zhou, Qingteng Zhang, Suresh Narayanan Coherent X-ray scattering techniques are often used to interrogate materials' structural and dynamical properties at mesoscopic time and length scales. In particular, X-ray photon correlation spectroscopy (XPCS) exploits correlations between scattered intensity fluctuations over time to derive insights about microscopic sample dynamics, from particle diffusion in colloidal suspensions to fluctuations of magnetic domains. However, the interpretation of complex XPCS signatures is often challenging or only in terms of approximate phenomenological models. In this work, we develop a machine learning framework to uncover mechanistic models from time-resolved coherent scattering measurements directly from data. Combining the method of neural differential equations with a computational forward model of the scattering method, we recover the time evolution of several model dynamical systems without access to real-space dynamics. We evaluate our approach against experimental considerations such as sampling and noise and discuss the interpretability of the learned models. Finally, we demonstrate a simple proof of concept for applying our framework to experimental data. |
Thursday, March 9, 2023 4:12PM - 4:24PM |
W45.00005: Elucidation of Relaxation Dynamics in Complex Fluids Through AI-informed X-ray Photon Correlation Spectroscopy James P Horwath, Xiao-Min Lin, Hongrui He, Qingteng Zhang, Eric M Dufresne, Subramanian K Sankaranarayanan, Wei Chen, Suresh Narayanan, Mathew Cherukara X-ray photon correlation spectroscopy (XPCS) is a useful technique for characterizing the dynamics of evolving systems and has been used successfully in combination with rheology measurements (rheo-XPCS) to observe the relaxation of complex fluids under shear in situ. However, out-of-equilibrium dynamics can produce a variety of unique and complex two-time correlation patterns which makes quantification of dynamics, or even establishing qualitative relationships between samples, extremely difficult. Meanwhile, machine learning and computer vision provide a wide range of unsupervised techniques for processing and understanding data without requiring input from the users, which can be applied to scientific data. |
Thursday, March 9, 2023 4:24PM - 4:36PM |
W45.00006: Resolving Elements at Atomic Scale in Metal Alloys with Synchrotron X-ray Scanning Tunneling Microscopy Lauren Kim, Ganesh Balasubramanian, TeYu Chien, Prince Sharma Scanning tunneling microscopy (STM) is a powerful tool in characterizing novel materials with topographic and electronic information at the atomic scale. However, it typically cannot distinguish between different types of elements. Using synchrotron X-ray scanning tunneling microscopy (SXSTM), we collect photo-ejected electrons due to the X-ray absorption at elemental adsorption edges with the STM tip, which provides elemental information at the nm scale. It has been demonstrated that the elemental resolution in SXSTM can be at the 2 nm scale. In this work, by using an Fe2Cr98 crystalline alloy, we demonstrate that the elemental resolution can reach the 1 nm scale. With this spatial resolution, nm scale X-ray absorption spectrum (XAS) can be achieved. This result indicates that SXSTM could be a promising technique to reveal the elemental distributions at the surfaces of multi-principal element alloys (MPEAs) and other high entropy materials, such as high entropy perovskite oxides and high entropy TMDs, at the atomic scale. |
Thursday, March 9, 2023 4:36PM - 4:48PM |
W45.00007: Looking for Chemical Shifts with Energy Dispersive Spectroscopy Rebekah M Jin, Yueyun Chen, Tristan O'Neill, Brian C Regan, Matthew H Mecklenburg Energy dispersive spectroscopy (EDS), a commonly employed spectroscopic technique, identifies elements using their characteristic x-rays. Under energetic electron irradiation, each element emits x-rays with energies particular to its unique atomic structure. Peaks occurring at these specific energies in EDS spectra are used to quantify elemental composition and identify material phases. Due to shot noise in the number of electron hole pairs produced in standard x-ray detectors, the full width at half-maximum of each peak is approximately 100 eV throughout the periodic table. This relatively poor energy resolution renders EDS seemingly unsuitable for the measurement of single or sub-eV effects such as chemical shifts, in which local chemical bonding modifies an atom's energy levels and its radiative electronic transitions. However, by curve fitting high-count x-ray peaks, we are able to measure and map chemical shifts using EDS in a transmission electron microscope. EDS shows promise for extending chemical shift mapping to heavy elements that cannot be effectively probed using electron energy loss spectroscopy (EELS) and x-ray photoelectron spectroscopy (XPS). |
Thursday, March 9, 2023 4:48PM - 5:00PM |
W45.00008: The 3-Ring Flash X-ray System: A Diagnostic for 3D Movies of Dynamic Events Kathryn Harke, Joseph W Tringe, Kyle Champley, Michael B Zellner, Sally Gonzales, James Daly, Taylor Benson, Steven Yep An X-ray diagnostic system has been developed at LLNL utilizing 15 separate 450kV flash X-ray systems spaced on three concentric rings with the capability of creating 3D movies of dynamic events. To accomplish dynamic X-ray computed tomography (CT), few-view reconstruction algorithms are utilized to reconstruct a single 3D rendering from a minimum of five separate source-detector pairs, yielding a maximum of a three-frame 3D movie. With a high explosives limit of 680 grams of TNT equivalent, spatial resolution ~ 1 mm, and temporal resolution ~ 0.01 µs, the 3-ring flash X-ray system can be used to probe several different mission spaces related to the fundamental and applied imaging of dynamic events. |
Thursday, March 9, 2023 5:00PM - 5:12PM |
W45.00009: Extreme methods of analysis (EMA) beamline at Brazilian Synchrotron Source (Sirius) Ricardo D Dos Reis, Guilherme Calligaris, Ulisses F Kaneko, Audrey D Grockowiak, Danusa do Carmo, Narcizo m Souza Neto The research exploring the limits of thermodynamical parameters, such as pressure, temperature, and magnetic field, is a fast-growing and fascinating discipline of science and technology that unravel many truths and facts of nature, which are not possible in ambient conditions. However, improving the quality of the experimental data obtained at extreme thermodynamical remains challenging. To understand the implication of such huge contraction, small focused X-ray beams, smaller than 1 micrometer, is essential to allow in-situ investigations of the crystalline and electronic structure of materials under high pressure. The Extreme condition Methods of Analysis beamline (EMA), of the new Brazilian light source, was designed to overcome this challenge by having both ~0.5x1 µm2 focused beam size with high photon flux (1013 photons/s @ 10 keV) and ~100x100 nm2 focused beam size (with ~1011 photons/s @ 10 keV), both with well-defined gaussian beam shape, which will allow the realization of X-ray absorption (XAS), X-ray diffraction (XRD), coherent diffraction image (CDI) and X-ray Raman experiments at extreme pressure with good spatial selectivity and also to avoid pressure gradients. As most complex scientific problems do need a combination of conditions to explore yet unreached points of the phase diagram, we aim at coupling the high-pressure capabilities to low and high temperatures (as low as 300 mK, as high as 8000 K) and high magnetic fields (up to 11T). |
Thursday, March 9, 2023 5:12PM - 5:24PM |
W45.00010: Entanglement Witness and Multi-point Correlations in Resonant Inelastic X-Ray Scattering Tongtong Liu, Yao Wang, Mingda Li Characterizing entanglement in quantum materials is crucial for next-generation quantum technologies. However, defining and measuring a quantifiable figure of merit for entanglement in a many-body quantum system is theoretically and experimentally challenging. The presence of entanglement in fermionic systems can be diagnosed by extracting entanglement witnesses from spectroscopies, which are directly related to the spin dynamic structure factors of the system. With cross-polarization, RIXS(Resonant inelastic X-ray scattering) approximates the spin and charge dynamic structure factors, which becomes exact at the ultra-short core-hole lifetime limit. Here, we propose a new RIXS technique that can extract higher-order correlations beyond the scope of the spin and charge structure factors. We verify our method using computational RIXS spectra, and theoretically propose a new entanglement witness of fermion systems. Using the extended Hubbard model and Kitaev honeycomb model as examples, we show the entanglement witness can quantify the multipartite entanglement in different phase regions. |
Thursday, March 9, 2023 5:24PM - 5:36PM |
W45.00011: Hard X-ray photoelectron spectroscopy (HAXPES) for material science applications Daniel A Beaton, Susanna Eriksson, Timo Wätjen, Tomas Weill, Marcus Lundwall, Peter Amann, T. Nishihara, Fred Henn, Bill Gerace, Xin Zhang Investigating buried interfaces, device electronics or batteries by chemically sensitive instrumentation is highly desired in materials science applications. X-ray photoelectron spectroscopy (XPS) is a powerful method to investigate the chemical nature of surfaces. However, investigations of buried interfaces occurring in, e.g., device electronics are difficult as the energies of the created photoelectrons are not high enough and scattering inside the material’s bulk limit the detected signal intensity. During the past decade, increased attention has been shown to hard X-rays in the photoelectron spectroscopy field. This is primarily due to the increased information depth enabled by the higher photon energies. Using Scienta Omicron’s HAXPES Lab, featuring a monochromatic Gallium K_alpha X-ray source in combination with a hemispherical electron analyzer that includes a +/- 30 degree acceptance angle, we were able to investigate buried interfaces, in-operando devices and real world samples. |
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