High-speed transmission electron microscope

Dömer, Holger; Bostanjoglo, O.

doi:10.1063/1.1611612

Cited by 95 publications

(59 citation statements)

References 12 publications

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“…In contrast, the single shot imaging method described here, while also following the developments of Bostanjoglo [4,[18][19][20][21][22][23], acquires an electron micrograph with a single pulse of electrons [24]. The requirement of image formation with a single pulse of electrons places stringent conditions on the electron emission and is controlled, as is usual in electron microscopy, by the brightness of the source [25].…”

Section: Introductionmentioning

confidence: 99%

Quantifying transient states in materials with the dynamic transmission electron microscope

Campbell

LaGrange

Kim

et al. 2010

Journal of Electron Microscopy

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(250 words)The Dynamic Transmission Electron Microscope (DTEM) offers a means of capturing rapid evolution in a specimen through in-situ microscopy experiments by allowing 15 ns electron micrograph exposure times. The rapid exposure time is enabled by creating a burst of electrons at the emitter by ultraviolet pulsed laser illumination. This burst arrives a specified time after a second laser initiates the specimen reaction. The timing of the two Q-switched lasers is controlled by highspeed pulse generators with a timing error much less than the pulse duration. Both diffraction and imaging experiments can be performed, just as in a conventional TEM. The brightness of the emitter and the total current control the spatial and temporal resolutions. We have demonstrated 7 nm spatial resolution in single 15 ns pulsed images. These single-pulse imaging experiments have been used to study martensitic transformations, nucleation and crystallization of an amorphous metal, and rapid chemical reactions. Measurements have been performed on these systems that are possible by no other experimental approaches currently available.2

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Section: Introductionmentioning

confidence: 99%

Quantifying transient states in materials with the dynamic transmission electron microscope

Campbell

LaGrange

Kim

et al. 2010

Journal of Electron Microscopy

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“…Conceptually, this works is based on the methods of time resolved electron diffraction (TRED) or ultrafast electron diffraction (UED) [1,[24][25][26]78,112], ultrafast electron crystallography (UEC) [23] and the other DTEM studies [21], but with one important difference-namely, the implementation of synchronized pulses of single electrons to form an image. The sketch of this 4D DTEM is shown in Figure 2.This single-electron approach differs quite remarkably from the one used in the work [27], which used single pulses with −10 8 electrons and pulse durations of −20 ns. Copyright © 2013 SciRes.…”

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confidence: 87%

Ultrafast Electron Microscopy for Chemistry, Biology and Material Science

Aseyev¹,

Weber²,

Ischenko³

2013

JASMI

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For the past thirty years, intense efforts have been made to record atomic scale movies that reveal the movement of atoms in molecules, the fast dynamical processes in biological tissues and cells, and the changes in the structure of a solid confined to nano-scale volumes. A combination of sub-nanometer spatial resolution with picosecond or even femtosecond temporal resolution is required for such atomic movies. Additional important information can be obtained when the energy of the electron beam transmitted through the sample is measured. The four dimensional (4D) spatially and temporally resolved ultrafast electron microscopy method is made possible by the extremely high detection efficiency that is reached in 4D electron microscopy. Using ultra-short electron bunches for the visualization of biological tissue can also improve the spatial resolution compared to conventional electron microscopes, thereby enabling the study of complex biological samples of relevance to the life sciences. Of particular interest to a broad audience is the possibility to create a video, and in the future, a real atomic movie, using 4D electron tomography. IntroductionSince the 1980s, intense efforts have been made to record an atomic movie showing the movements of atoms within molecules, the fast dynamical processes in biological tissues and cells, and the changes in the structure of a solid in a nano-scale volume [1][2][3]. Such an atomic movie requires a combination of sub-nanometer spatial resolution with picosecond or even femtosecond temporal resolution. The aim of any microscopy is to study the structure, composition, and a variety of physical and chemical characteristics of samples (usually solids) on a very small length scale, with linear dimensions of irregularities that are on the order of micrometers or nanometers. While in most microscopies, photon beams (in optical microscopy) or corpusclar beams (for example in electron microscopy) are used as the probes, tunneling microscopies use a very sharp tip that is scanned across surfaces. Electron microscopy and optical microscopy use light and a focused electron beam for imaging, respectively. Beyond those, other microscopic methods may use ions, protons, positrons, or neutrons, or acoustic or microwave radiation in addition to other, less common, methods [3][4][5][6]. In each of them, the specificity of the interaction of a beam of the particles (or photons) and the molecules or atoms of a sample yield unique and rather useful information about the structure, composition and microscopic inhomogeneities of the sample, and the nature of their intermolecular interactions [3,4,7]. For example, the slow neutrons in neutron microscopy and spectroscopy barely interact with the electrons, but interact strongly with the nuclei of the atoms.There are two main approaches to achieve imaging in classical microscopy: 1) In transmission mode, a large area of the sample is illuminated by a beam of light or particles. Specifically designed lenses project the transmitted beam onto a...

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“…Sub-nanometer resolution is predicted (particularly with amplitude contrast mechanisms) if objective lens aberrations dominate the resolution limit. The experimental limit is closer to 100 nm [1], and is likely due to a combination of low signal levels and electron-electron scattering in the post-sample crossovers.…”

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confidence: 99%

“…Most current in-situ TEM investigations are limited to video-rate imaging, but this is more a limitation of the detector than of the electron optics. Previous work at TU Berlin has demonstrated the ability of the TEM to take images and movies on a nanosecond time scale [1]. This has formed the basis of efforts at Lawrence Livermore National Laboratory and elsewhere to push these techniques to their limits, developing the next generation of so-called dynamic TEM's (DTEM's), which are intended to achieve sub-nanosecond time resolution.…”

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confidence: 99%

Electron Optical Requirements for Sub-Nanosecond Microscopy

Reed

Armstrong

King

2005

MAM

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It is self-evident that improving the time resolution of an in-situ technique opens up entirely new realms of physical processes for investigation. The field of optics, with its well-developed femtosecond techniques, has been reaping these benefits for some time. Short-pulse x-ray and ultrafast electron diffraction (UED) approaches are very much on the rise and are producing stunning results of their own.A movement is afoot to similarly improve the time resolution of imaging in the transmission electron microscope (TEM). The TEM has a unique ability to produce high-quality real-space images with sub-nanometer resolution and high frame rates. Most current in-situ TEM investigations are limited to video-rate imaging, but this is more a limitation of the detector than of the electron optics. Previous work at TU Berlin has demonstrated the ability of the TEM to take images and movies on a nanosecond time scale [1]. This has formed the basis of efforts at Lawrence Livermore National Laboratory and elsewhere to push these techniques to their limits, developing the next generation of so-called dynamic TEM's (DTEM's), which are intended to achieve sub-nanosecond time resolution.As part of this effort, we have investigated the theoretical limits of ultrafast electron microscopy. We have found that the design of the entire column may have to be re-thought in order to operate well under the high beam currents (several mA) occurring in a DTEM pulse. The gun (replaced with a pulsed photocathode) has to be optimized not for stability and spatial coherence (as in standard TEM) but for raw electron output (Figure 1). This suggests some significant redesigns. Boersch, space charge, and trajectory displacement effects, while relatively minor nuisances in standard TEM, become stringent limits on the DTEM capabilities, while the effects that normally limit spatial resolution (an optimal compromise between aberrations, defocus, and diffraction limits) are almost irrelevant (Figure 2). In fact, the current DTEM resolution limit is probably not in the objective lens at all. The intermediate/projector lens system will encounter the same trajectory displacement problems that limit resolution in electron projection lithography systems to some tens of nm [2].Having identified the limitations in present systems, we can develop approaches for surpassing them. An important step will be to incorporate the results in related fields (accelerator physics, projection lithography, and streak camera design) to help us fundamentally rethink how a fast TEM should work. Future systems may be built around radio-frequency MeV electron sources, with pulse compression, dynamic aberration correction, advanced detection methods, and unusual lens designs. References[1] H. Domer and O.

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High-speed transmission electron microscope

Cited by 95 publications

References 12 publications

Quantifying transient states in materials with the dynamic transmission electron microscope

Quantifying transient states in materials with the dynamic transmission electron microscope

Ultrafast Electron Microscopy for Chemistry, Biology and Material Science

Electron Optical Requirements for Sub-Nanosecond Microscopy

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