The effect of Coulomb repulsion on the space-time resolution limits for ultrafast electron diffraction

Ischenko, A. A.; Кочиков, И. В.; Miller, R. J. Dwayne

doi:10.1063/1.5060673

Cited by 13 publications

(9 citation statements)

References 48 publications

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“…A first example of envelope equations is found in one of the first quantitative studies of non-relativistic space-charge driven bunch lengthening using simple analytical models (Ischenko et al, 2019;Reed, 2006;Siwick et al, 2002). In this case the radial beam envelope was assumed constant and there is only one equation to be solved for the longitudinal beam size.…”

Section: Space Charge Effectsmentioning

confidence: 99%

Ultrafast Electron Diffraction: Visualizing Dynamic States of Matter

Filippetto,

Musumeci,

et al. 2022

Preprint

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Since the discovery of electron-wave duality, electron scattering instrumentation has developed into a powerful array of techniques for revealing the atomic structure of matter. Beyond detecting local lattice variations in equilibrium structures with the highest possible spatial resolution, recent research efforts have been directed towards the long sought-after dream of visualizing the dynamic evolution of matter in real-time. The atomic behavior at ultrafast timescales carries critical information on phase transition and chemical reaction dynamics, the coupling of electronic and nuclear degrees of freedom in materials and molecules, the correlation between structure, function and previously hidden metastable or nonequilibrium states of matter. Ultrafast electron pulses play an essential role in this scientific endeavor, and their generation has been facilitated by rapid technical advances in both ultrafast laser and particle accelerator technologies. This review presents a summary of the remarkable developments in this field over the last few decades. The physics and technology of ultrafast electron beams is presented with an emphasis on the figures of merit most relevant for ultrafast electron diffraction (UED) experiments. We discuss recent developments in the generation, manipulation and characterization of ultrashort electron beams aimed at improving the combined spatio-temporal resolution of these measurements. The fundamentals of electron scattering from atomic matter and the theoretical frameworks for retrieving dynamic structural information from solid-state and gas-phase samples is described. Essential experimental techniques and several landmark works that have applied these approaches are also highlighted to demonstrate the widening applicability of these methods. Ultrafast electron probes with ever improving capabilities, combined with other complementary photonbased or spectroscopic approaches, hold tremendous potential for revolutionizing our ability to observe and understand energy and matter at atomic scales.

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Section: Space Charge Effectsmentioning

confidence: 99%

Ultrafast Electron Diffraction: Visualizing Dynamic States of Matter

Filippetto,

Musumeci,

et al. 2022

Preprint

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“…Taken CH 3 Br as an example, the spatial and temporal resolution required for reconstructing density matrix up to N = 5 is Δ r = 3.1 pm and Δ t = 4.6 fs, respectively. In other words, the spatial resolution has to be sufficient to directly resolve the nodes of the vibrational wavepacket, which is within reach by electron diffraction with a sufficient number of registered electrons …”

Section: Spatial Temporal Resolution For Quantum Tomography and Stati...mentioning

confidence: 99%

“…For chemical reactions involving electron transfer, the barrier is defined by the reorganization energy to stabilize the charge-separated state. ,, These motions involve normally a large number of intermolecular and intramolecular displacements in response to the reaction field associated with electron transfer, ,− ,− ,− and the magnitude of these motions can be on the order of 0.01 to 0.1 Å. − This spatial resolution is only nominally within reach with X-ray diffraction methods and is generally more readily accessed with electrons for the simple reason that the de Broglie wavelength of high energy electrons is more than an order of magnitude smaller than hard X-rays typically used for diffraction studies. As a case in point, the most accurate information on bond lengths in molecular systems come from static gas phase electron diffraction studies that can determine bond lengths with a precision of 0.001 Å. − …”

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confidence: 99%

Mapping Atomic Motions with Electrons: Toward the Quantum Limit to Imaging Chemistry

Gyawali

Ischenko

et al. 2019

ACS Photonics

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Recent advances in ultrafast electron and X-ray diffraction have pushed imaging of structural dynamics into the femtosecond time domain, that is, the fundamental time scale of atomic motion. New physics can be reached beyond the scope of traditional diffraction or reciprocal space imaging. By exploiting the high time resolution, it has been possible to directly observe the collapse of nearly innumerable possible nuclear motions to a few key reaction modes that direct chemistry. It is this reduction in dimensionality in the transition state region that makes chemistry a transferable concept, with the same class of reactions being applicable to synthetic strategies to nearly arbitrary levels of complexity. The ability to image the underlying key reaction modes has been achieved with resolution to relative changes in atomic positions to better than 0.01 Å, that is, comparable to thermal motions. We have effectively reached the fundamental space-time limit with respect to the reaction energetics and imaging the acting forces. In the process of ensemble measured structural changes, we have missed the quantum aspects of chemistry. This perspective reviews the current state of the art in imaging chemistry in action and poses the challenge to access quantum information on the dynamics. There is the possibility with the present ultrabright electron and X-ray sources, at least in principle, to do tomographic reconstruction of quantum states in the form of a Wigner function and density matrix for the vibrational, rotational, and electronic degrees of freedom. Accessing this quantum information constitutes the ultimate demand on the spatial and temporal resolution of reciprocal space imaging of chemistry. Given the much shorter wavelength and corresponding intrinsically higher spatial resolution of current electron sources over X-rays, this Perspective will focus on electrons to provide an overview of the challenge on both the theory and the experimental fronts to extract the quantum aspects of molecular dynamics.

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“…Considering the spatial resolution for experimentally imaging such structural dynamics, the length scale for chemical bonds is Ångstrom and the accurate value can be determined from static gas phase electron diffraction with 0.001 Åprecision [4,5]. For example, in chemical reactions, intramolecular and intermolecular electron transfer play an important role in stabilizing the configuration under a proper energy [6,7].…”

Section: Introductionmentioning

confidence: 99%

Perspective: Ultrafast Imaging of Molecular Dynamics Using Ultrafast Low-Frequency Lasers, X-ray Free Electron Laser and Electron Pulses

Zhang¹,

Guo²,

Mi³

et al. 2022

Preprint

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The requirement of high space-time resolution and brightness is a great challenge for imaging atomic motion and making molecular movies. Important breakthroughs in ultrabright tabletop laser, x-ray and electron sources have enabled the direct imaging of evolving molecular structures in chemical processes.And recent experimental advances in preparing ultrafast laser and electron pulses equipped molecular imaging with femtosecond time resolution. This Perspectives present an overview of versatile imaging methods of molecular dynamics. High-order harmonic generation imaging maps the harmonic order of photons to the time delay for nuclear motion and can reach attosecond time resolution. Coulomb explosion imaging retrieves molecular structural information by detecting the momentum vectors of fragmented ions. Diffraction imaging encodes molecular structural and electronic information in reciprocal space, achieving high spatial resolution by using x-ray or electrons with short wavelengths. The enhancement of x-ray and electron source brightness pushes diffraction into single molecular limit without the restriction of crystalline materials. Laser-induced electron diffraction is a self-imaging method based on coherent electron scattering. We also present various applications of these ultrafast imaging methods in resolving laser-induced nuclear and electronic dynamics, as well as dynamic symmetry evolution of molecules.

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The effect of Coulomb repulsion on the space-time resolution limits for ultrafast electron diffraction

Cited by 13 publications

References 48 publications

Ultrafast Electron Diffraction: Visualizing Dynamic States of Matter

Ultrafast Electron Diffraction: Visualizing Dynamic States of Matter

Mapping Atomic Motions with Electrons: Toward the Quantum Limit to Imaging Chemistry

Perspective: Ultrafast Imaging of Molecular Dynamics Using Ultrafast Low-Frequency Lasers, X-ray Free Electron Laser and Electron Pulses

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