The simulation optimization and an experimental demonstration of improved performances of mega-electron-volt ultrafast electron diffraction (MeV UED) are reported in this paper. Using ultrashort high quality electron pulses from an S-band photocathode rf gun and a polycrystalline aluminum foil as the sample, we experimentally demonstrated an improved spatial resolution of MeV UED, in which the Debye-Scherrer rings of the (111) and (200) planes were clearly resolved. This result showed that MeV UED is capable to achieve an atomic level spatial resolution and a approximately 100 fs temporal resolution simultaneously, and will be a unique tool for ultrafast structural dynamics studies.
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http://dx.doi.org/10.1063/1.3194047 | DOI Listing |
Ultramicroscopy
January 2025
FREIA Laboratory, Department of Physics and Astronomy, Uppsala University, Å ngströmlaboratoriet, 75120 Uppsala, Sweden; RIKEN, SPring-8, 679-5148 Hyogo, Japan.
We review state-of-the-art electron beams for single-shot megaelectronvolt ultrafast electron diffraction (MeV-UED) and compact light sources. Our primary focus is on sub-100 femtosecond electron bunches in the 2-30 MeV energy range. We demonstrate that our new and recent simulation results permit significantly improved bunch parameters for these applications.
View Article and Find Full Text PDFJ Am Chem Soc
October 2024
Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
For many chemical reactions, it remains notoriously difficult to predict and experimentally determine the rates and branching ratios between different reaction channels. This is particularly the case for reactions involving short-lived intermediates, whose observation requires ultrafast methods. The UV photochemistry of bromoform (CHBr) is among the most intensely studied photoreactions.
View Article and Find Full Text PDFJ Chem Phys
July 2024
Departamento de Química, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
Over the years, theoretical calculations and scalable computer simulations have complemented ultrafast experiments, as they offer the advantage of overcoming experimental restrictions and having access to the whole dynamics. This synergy between theory and experiment promises to yield a deeper understanding of photochemical processes, offering valuable insights into the behavior of complex systems at the molecular level. However, the ability of theoretical models to predict ultrafast experimental outcomes has remained largely unexplored.
View Article and Find Full Text PDFNat Commun
June 2024
SLAC National Accelerator Laboratory, Menlo Park, 94025, California, USA.
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.
View Article and Find Full Text PDFStruct Dyn
May 2024
Radiation Center for Ultrafast Science, Korea Atomic Energy Research Institute (KAERI), Daejeon 34057, South Korea.
The structure of molecules, particularly the dynamic changes in structure, plays an essential role in understanding physical and chemical phenomena. Time-resolved (TR) scattering techniques serve as crucial experimental tools for studying structural dynamics, offering direct sensitivity to molecular structures through scattering signals. Over the past decade, the advent of x-ray free-electron lasers (XFELs) and mega-electron-volt ultrafast electron diffraction (MeV-UED) facilities has ushered TR scattering experiments into a new era, garnering significant attention.
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