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Ji F, Edelen A, Roussel R, Shen X, Miskovich S, Weathersby S, Luo D, Mo M, Kramer P, Mayes C, Othman MAK, Nanni E, Wang X, Reid A, Minitti M, England RJ. Multi-objective Bayesian active learning for MeV-ultrafast electron diffraction. Nat Commun 2024; 15:4726. [PMID: 38830874 PMCID: PMC11148007 DOI: 10.1038/s41467-024-48923-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 05/16/2024] [Indexed: 06/05/2024] Open
Abstract
Ultrafast electron diffraction using MeV energy beams(MeV-UED) has enabled unprecedented scientific opportunities in the study of ultrafast structural dynamics in a variety of gas, liquid and solid state systems. Broad scientific applications usually pose different requirements for electron probe properties. Due to the complex, nonlinear and correlated nature of accelerator systems, electron beam property optimization is a time-taking process and often relies on extensive hand-tuning by experienced human operators. Algorithm based efficient online tuning strategies are highly desired. Here, we demonstrate multi-objective Bayesian active learning for speeding up online beam tuning at the SLAC MeV-UED facility. The multi-objective Bayesian optimization algorithm was used for efficiently searching the parameter space and mapping out the Pareto Fronts which give the trade-offs between key beam properties. Such scheme enables an unprecedented overview of the global behavior of the experimental system and takes a significantly smaller number of measurements compared with traditional methods such as a grid scan. This methodology can be applied in other experimental scenarios that require simultaneously optimizing multiple objectives by explorations in high dimensional, nonlinear and correlated systems.
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Affiliation(s)
- Fuhao Ji
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA.
| | - Auralee Edelen
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
| | - Ryan Roussel
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
| | - Xiaozhe Shen
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
| | - Sara Miskovich
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
| | - Stephen Weathersby
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
| | - Duan Luo
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
| | - Mianzhen Mo
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
| | - Patrick Kramer
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
| | - Christopher Mayes
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
| | - Mohamed A K Othman
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
| | - Emilio Nanni
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
| | - Xijie Wang
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
| | - Alexander Reid
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
| | - Michael Minitti
- SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA
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Sun X, Williams J, Sharma S, Kunjir S, Morris D, Zhao S, Ruan CY. Precision-controlled ultrafast electron microscope platforms. A case study: Multiple-order coherent phonon dynamics in 1T-TaSe 2 probed at 50 fs-10 fm scales. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2024; 11:024305. [PMID: 38566810 PMCID: PMC10987196 DOI: 10.1063/4.0000242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Accepted: 03/08/2024] [Indexed: 04/04/2024]
Abstract
We report on the first detailed beam tests attesting the fundamental principle behind the development of high-current-efficiency ultrafast electron microscope systems where a radio frequency (RF) cavity is incorporated as a condenser lens in the beam delivery system. To allow for the experiment to be carried out with a sufficient resolution to probe the performance at the emittance floor, a new cascade loop RF controller system is developed to reduce the RF noise floor. Temporal resolution at 50 fs in full-width-at-half-maximum and detection sensitivity better than 1% are demonstrated on exfoliated 1T-TaSe2 system under a moderate repetition rate. To benchmark the performance, multi-terahertz edge-mode coherent phonon excitation is employed as the standard candle. The high temporal resolution and the significant visibility to very low dynamical contrast in diffraction signals via high-precision phase-space manipulation give strong support to the working principle for the new high-brightness femtosecond electron microscope systems.
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Affiliation(s)
- Xiaoyi Sun
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - Joseph Williams
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - Sachin Sharma
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - Shriraj Kunjir
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
| | - Dan Morris
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
| | - Shen Zhao
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan 48824, USA
| | - Chong-Yu Ruan
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
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3
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Time-resolved transmission electron microscopy for nanoscale chemical dynamics. Nat Rev Chem 2023; 7:256-272. [PMID: 37117417 DOI: 10.1038/s41570-023-00469-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2023] [Indexed: 02/24/2023]
Abstract
The ability of transmission electron microscopy (TEM) to image a structure ranging from millimetres to Ångströms has made it an indispensable component of the toolkit of modern chemists. TEM has enabled unprecedented understanding of the atomic structures of materials and how structure relates to properties and functions. Recent developments in TEM have advanced the technique beyond static material characterization to probing structural evolution on the nanoscale in real time. Accompanying advances in data collection have pushed the temporal resolution into the microsecond regime with the use of direct-electron detectors and down to the femtosecond regime with pump-probe microscopy. Consequently, studies have deftly applied TEM for understanding nanoscale dynamics, often in operando. In this Review, time-resolved in situ TEM techniques and their applications for probing chemical and physical processes are discussed, along with emerging directions in the TEM field.
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Xiang X, Duxbury PM, Zerbe B. Longitudinal crossover and the dynamics of uniform electron ellipsoids focused by a linear chirp. Phys Rev E 2021; 103:023202. [PMID: 33736005 DOI: 10.1103/physreve.103.023202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 12/23/2020] [Indexed: 11/07/2022]
Abstract
High-resolution single-shot nonrelativistic ultrafast electron microscopy (UEM) relies on adaptive optics to compress high-intensity bunches using radio frequency (RF) cavities. We present a comprehensive discussion of the analytic approaches available to characterize bunch dynamics as an electron bunch goes through a longitudinal focal point after an RF cavity where space charge effects can be large. Methods drawn from the Coulomb explosion literature, the accelerator physics literature, and the analytic Gaussian model developed for UEM are compared, utilized, and extended in some cases. In particular the longitudinal focus may occur in two different regimes, a bounce-back regime and a crossover regime; and we characterize the critical point separating these regimes in the zero-emittance model. Results from N-particle simulations using efficient multipole methods are compared to the theoretical models revealing features requiring extensions of the analytic approaches; and in particular mechanisms for emittance growth and transfer are discussed.
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Affiliation(s)
- X Xiang
- Department of Physics and Astronomy, Michigan State University, 567 Wilson Rd., East Lansing, MI 48224
| | - P M Duxbury
- Department of Physics and Astronomy, Michigan State University, 567 Wilson Rd., East Lansing, MI 48224
| | - B Zerbe
- Department of Physics and Astronomy, Michigan State University, 567 Wilson Rd., East Lansing, MI 48224
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5
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Nonequilibrium dynamics of spontaneous symmetry breaking into a hidden state of charge-density wave. Nat Commun 2021; 12:566. [PMID: 33495452 PMCID: PMC7835373 DOI: 10.1038/s41467-020-20834-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 12/23/2020] [Indexed: 11/08/2022] Open
Abstract
Nonequilibrium phase transitions play a pivotal role in broad physical contexts, from condensed matter to cosmology. Tracking the formation of nonequilibrium phases in condensed matter requires a resolution of the long-range cooperativity on ultra-short timescales. Here, we study the spontaneous transformation of a charge-density wave in CeTe3 from a stripe order into a bi-directional state inaccessible thermodynamically but is induced by intense laser pulses. With ≈100 fs resolution coherent electron diffraction, we capture the entire course of this transformation and show self-organization that defines a nonthermal critical point, unveiling the nonequilibrium energy landscape. We discuss the generation of instabilities by a swift interaction quench that changes the system symmetry preference, and the phase ordering dynamics orchestrated over a nonadiabatic timescale to allow new order parameter fluctuations to gain long-range correlations. Remarkably, the subsequent thermalization locks the remnants of the transient order into longer-lived topological defects for more than 2 ns.
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Sun S, Sun X, Bartles D, Wozniak E, Williams J, Zhang P, Ruan CY. Direct imaging of plasma waves using ultrafast electron microscopy. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:064301. [PMID: 33415182 PMCID: PMC7772000 DOI: 10.1063/4.0000044] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 11/30/2020] [Indexed: 06/12/2023]
Abstract
A femtosecond plasma imaging modality based on a new development of ultrafast electron microscope is introduced. We investigated the laser-induced formation of high-temperature electron microplasmas and their subsequent non-equilibrium evolution. Based on a straightforward field imaging principle, we directly retrieve detailed information about the plasma dynamics, including plasma wave structures, particle densities, and temperatures. We discover that directly subjected to a strong magnetic field, the photo-generated microplasmas manifest in novel transient cyclotron echoes and form new wave states across a broad range of field strengths and different laser fluences. Intriguingly, the transient cyclotron waves morph into a higher frequency upper-hybrid wave mode with the dephasing of local cyclotron dynamics. The quantitative real-space characterizations of the non-equilibrium plasma systems demonstrate the feasibilities of a new microscope system in studying the plasma dynamics or transient electric fields with high spatiotemporal resolutions.
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Affiliation(s)
- Shuaishuai Sun
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - Xiaoyi Sun
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - Daniel Bartles
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - Elliot Wozniak
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - Joseph Williams
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - Peng Zhang
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824, USA
| | - Chong-Yu Ruan
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
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7
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Fu X, Wang E, Zhao Y, Liu A, Montgomery E, Gokhale VJ, Gorman JJ, Jing C, Lau JW, Zhu Y. Direct visualization of electromagnetic wave dynamics by laser-free ultrafast electron microscopy. SCIENCE ADVANCES 2020; 6:6/40/eabc3456. [PMID: 33008895 PMCID: PMC7852396 DOI: 10.1126/sciadv.abc3456] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 08/19/2020] [Indexed: 06/11/2023]
Abstract
Integrating femtosecond lasers with electron microscopies has enabled direct imaging of transient structures and morphologies of materials in real time and space. Here, we report the development of a laser-free ultrafast electron microscopy (UEM) offering the same capability but without requiring femtosecond lasers and intricate instrumental modifications. We create picosecond electron pulses for probing dynamic events by chopping a continuous beam with a radio frequency (RF)-driven pulser with the pulse repetition rate tunable from 100 MHz to 12 GHz. As a first application, we studied gigahertz electromagnetic wave propagation dynamics in an interdigitated comb structure. We reveal, on nanometer space and picosecond time scales, the transient oscillating electromagnetic field around the tines of the combs with time-resolved polarization, amplitude, and local field enhancement. This study demonstrates the feasibility of laser-free UEM in real-space visualization of dynamics for many research fields, especially the electrodynamics in devices associated with information processing technology.
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Affiliation(s)
- Xuewen Fu
- Condensed Matter Physics and Material Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
- School of Physics, Nankai University, Tianjin 300071, China
| | - Erdong Wang
- Collider-Accelerator Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Yubin Zhao
- Euclid Techlabs LLC, 365 Remington Blvd., Bolingbrook, IL 60440, USA
| | - Ao Liu
- Euclid Techlabs LLC, 365 Remington Blvd., Bolingbrook, IL 60440, USA
| | - Eric Montgomery
- Euclid Techlabs LLC, 365 Remington Blvd., Bolingbrook, IL 60440, USA
| | - Vikrant J Gokhale
- Microsystems and Nanotechnology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Jason J Gorman
- Microsystems and Nanotechnology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Chunguang Jing
- Euclid Techlabs LLC, 365 Remington Blvd., Bolingbrook, IL 60440, USA
| | - June W Lau
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Yimei Zhu
- Condensed Matter Physics and Material Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
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Zandi O, Sykes AE, Cornelius RD, Alcorn FM, Zerbe BS, Duxbury PM, Reed BW, van der Veen RM. Transient lensing from a photoemitted electron gas imaged by ultrafast electron microscopy. Nat Commun 2020; 11:3001. [PMID: 32532996 PMCID: PMC7293293 DOI: 10.1038/s41467-020-16746-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 05/18/2020] [Indexed: 11/28/2022] Open
Abstract
Understanding and controlling ultrafast charge carrier dynamics is of fundamental importance in diverse fields of (quantum) science and technology. Here, we create a three-dimensional hot electron gas through two-photon photoemission from a copper surface in vacuum. We employ an ultrafast electron microscope to record movies of the subsequent electron dynamics on the picosecond-nanosecond time scale. After a prompt Coulomb explosion, the subsequent dynamics is characterized by a rapid oblate-to-prolate shape transformation of the electron gas, and periodic and long-lived electron cyclotron oscillations inside the magnetic field of the objective lens. In this regime, the collective behavior of the oscillating electrons causes a transient, mean-field lensing effect and pronounced distortions in the images. We derive an analytical expression for the time-dependent focal length of the electron-gas lens, and perform numerical electron dynamics and probe image simulations to determine the role of Coulomb self-fields and image charges. This work inspires the visualization of cyclotron dynamics inside two-dimensional electron-gas materials and enables the elucidation of electron/plasma dynamics and properties that could benefit the development of high-brightness electron and X-ray sources.
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Affiliation(s)
- Omid Zandi
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Allan E Sykes
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Ryan D Cornelius
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Francis M Alcorn
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Brandon S Zerbe
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA
| | - Phillip M Duxbury
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA
| | - Bryan W Reed
- Integrated Dynamic Electron Solutions, Inc. (IDES), Pleasanton, CA, 94588, USA
| | - Renske M van der Veen
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
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