Transmission electron microscopy with atomic resolution under atmospheric pressures

Dai, Sheng; Gao, Wenpei; Zhang, Shuyi; Graham, George W.; Pan, Xiaoqing

doi:10.1557/mrc.2017.125

Cited by 27 publications

(25 citation statements)

References 88 publications

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“…The authors highlighted that SiN x windows should be amorphous to avoid added electron diffraction contrast [60], which would be detrimental to TEM observations. This [26,85] and [86] nanoreactor marked a clear turn in approach for environmental TEM study [26].…”

Section: Gas Cellsmentioning

confidence: 99%

“…The accessibility of gas cell TEM holders has made them increasingly ubiquitous for the characterization of heterogeneous catalysts [9,25]. The technique has garnered attention from all sub-fields of catalysis [8,9,26].…”

Section: Gas Cellsmentioning

confidence: 99%

“…in a controlled environment such as a solution or reaction gas mixture, or operando, when the catalytic conversion is Fig. 1 Chronology of major MEMS and in situ TEM developments additionally measured alongside TEM observations [22][23][24][25][26]. The operando approach can help establish detailed local structure-property relationships.…”

Section: Introductionmentioning

confidence: 99%

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Quo Vadis Micro-Electro-Mechanical Systems for the Study of Heterogeneous Catalysts Inside the Electron Microscope?

et al. 2020

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During the last decade, modern micro-electro-mechanical systems (MEMS) technology has been used to create cells that can act as catalytic nanoreactors and fit into the sample holders of transmission electron microscopes. These nanoreactors can maintain atmospheric or higher pressures inside the cells as they seal gases or liquids from the vacuum of the TEM column and can reach temperatures exceeding 1000 °C. This has led to a paradigm shift in electron microscopy, which facilitates the local characterization of structural and morphological changes of solid catalysts under working conditions. In this review, we outline the development of state-of-the-art nanoreactor setups that are commercially available and are currently applied to study catalytic reactions in situ or operando in gaseous or liquid environments. We also discuss challenges that are associated with the use of environmental cells. In catalysis studies, one of the major challenge is the interpretation of the results while considering the discrepancies in kinetics between MEMS based gas cells and fixed bed reactors, the interactions of the electron beam with the sample, as well as support effects. Finally, we critically analyze the general role of MEMS based nanoreactors in electron microscopy and catalysis communities and present possible future directions.

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Section: Gas Cellsmentioning

confidence: 99%

Section: Gas Cellsmentioning

confidence: 99%

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Quo Vadis Micro-Electro-Mechanical Systems for the Study of Heterogeneous Catalysts Inside the Electron Microscope?

et al. 2020

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“…This review article emphasizes the technique perspective of windowed gas cells more, and hence some of the catalysis-related discussions are not fully covered. If the viewer is interested in a more detailed review of the catalysis application on gas cell, please check out this review written by Dai et al in 2017 [25]. We hope that this review can provide the reader with a unique perspective on the field of catalysis development.…”

Section: Introductionmentioning

confidence: 99%

In Situ TEM Studies of Catalysts Using Windowed Gas Cells

Fan

Dai

et al. 2020

Catalysts

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For decades, differentially pumped environmental transmission electron microscopy has been a powerful tool to study dynamic structural evolution of catalysts under a gaseous environment. With the advancement of micro-electromechanical system-based technologies, windowed gas cell became increasingly popular due to its ability to achieve high pressure and its compatibility to a wide range of microscopes with minimal modification. This enables a series of imaging and analytical technologies such as atomic resolution imaging, spectroscopy, and operando, revealing details that were unprecedented before. By reviewing some of the recent work, we demonstrate that the windowed gas cell has the unique ability to solve complicated catalysis problems. We also discuss what technical difficulties need to be addressed and provide an outlook for the future of in situ environmental transmission electron microscopy (TEM) technologies and their application to the field of catalysis development.

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“…Microscopy techniques have undergone a steep advance in recent years, allowing ultra-high resolution imaging and three-dimensional reconstruction of the imaged features [1]- [4]. A number of modes of operation and set-ups have been applied to organic and inorganic samples under different environments, in which one of the final goals is to discern their morphological features [5]- [7]. In this sense, distinct free software applications for image analysis…”

Section: Introductionmentioning

confidence: 99%

Morphology Clustering Software for AFM Images, Based on Particle Isolation and Artificial Neural Networks

et al. 2019

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Advanced microscopy techniques currently allow scientists to visualize biomolecules at high resolution. Among them, atomic force microscopy (AFM) shows the advantage of imaging molecules in their native state, without requiring any staining or coating of the sample. Biopolymers, including proteins and structured nucleic acids, are flexible molecules that can fold into alternative conformations for any given monomer sequence, as exemplified by the different three-dimensional structures adopted by RNA in solution. Therefore, the manual analysis of images visualized by AFM and other microscopy techniques becomes very laborious and time-consuming (and may also be inadvertently biased) when large populations of biomolecules are studied. Here we present a novel morphology clustering software, based on particle isolation and artificial neural networks, which allows the automatic image analysis and classification of biomolecules that can show alternative conformations. It has been tested with a set of AFM images of RNA molecules (a 574 nucleotides-long functinal region of the hepatitis C virus genome that contains its internal ribosome entry site element) structured in folding buffers containing 0, 2, 4, 6 or 10 mM Mg 2+. The developed software shows a broad applicability in the microscopy-based analysis of biopolymers and other complex biomolecules. INDEX TERMS Artificial neural networks, atomic force microscopy (AFM), biomolecules, growing cell structures (GCS), hepatitis C virus (HCV), Image analysis, internal ribosome entry site (IRES), ribonucleic acid (RNA), self-organizing maps (SOM).

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Transmission electron microscopy with atomic resolution under atmospheric pressures

Abstract: Abstract

Cited by 27 publications

References 88 publications

Quo Vadis Micro-Electro-Mechanical Systems for the Study of Heterogeneous Catalysts Inside the Electron Microscope?

Quo Vadis Micro-Electro-Mechanical Systems for the Study of Heterogeneous Catalysts Inside the Electron Microscope?

In Situ TEM Studies of Catalysts Using Windowed Gas Cells

Morphology Clustering Software for AFM Images, Based on Particle Isolation and Artificial Neural Networks

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