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Quigley F, McBean P, O'Donovan P, Peters JJP, Jones L. Cost and Capability Compromises in STEM Instrumentation for Low-Voltage Imaging. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2022; 28:1-7. [PMID: 35354509 DOI: 10.1017/s1431927622000277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Low-voltage transmission electron microscopy (≤80 kV) has many applications in imaging beam-sensitive samples, such as metallic nanoparticles, which may become damaged at higher voltages. To improve resolution, spherical aberration can be corrected for in a scanning transmission electron microscope (STEM); however, chromatic aberration may then dominate, limiting the ultimate resolution of the microscope. Using image simulations, we examine how a chromatic aberration corrector, different objective lenses, and different beam energy spreads each affect the image quality of a gold nanoparticle imaged at low voltages in a spherical aberration-corrected STEM. A quantitative analysis of the simulated examples can inform the choice of instrumentation for low-voltage imaging. We here demonstrate a methodology whereby the optimum energy spread to operate a specific STEM can be deduced. This methodology can then be adapted to the specific sample and instrument of the reader, enabling them to make an informed economical choice as to what would be most beneficial for their STEM in the cost-conscious landscape of scientific infrastructure.
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Affiliation(s)
- Frances Quigley
- School of Physics, Trinity College Dublin, Dublin 2, Ireland
- Advanced Microscopy Laboratory, Centre for Research on Adaptive Nanostructures & Nanodevices (CRANN), Dublin 2, Ireland
| | - Patrick McBean
- School of Physics, Trinity College Dublin, Dublin 2, Ireland
- Advanced Microscopy Laboratory, Centre for Research on Adaptive Nanostructures & Nanodevices (CRANN), Dublin 2, Ireland
| | - Peter O'Donovan
- School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | - Jonathan J P Peters
- School of Physics, Trinity College Dublin, Dublin 2, Ireland
- Advanced Microscopy Laboratory, Centre for Research on Adaptive Nanostructures & Nanodevices (CRANN), Dublin 2, Ireland
| | - Lewys Jones
- School of Physics, Trinity College Dublin, Dublin 2, Ireland
- Advanced Microscopy Laboratory, Centre for Research on Adaptive Nanostructures & Nanodevices (CRANN), Dublin 2, Ireland
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Liu JJ. Advances and Applications of Atomic-Resolution Scanning Transmission Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2021; 27:1-53. [PMID: 34414878 DOI: 10.1017/s1431927621012125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Although scanning transmission electron microscopy (STEM) images of individual heavy atoms were reported 50 years ago, the applications of atomic-resolution STEM imaging became wide spread only after the practical realization of aberration correctors on field-emission STEM/TEM instruments to form sub-Ångstrom electron probes. The innovative designs and advances of electron optical systems, the fundamental understanding of electron–specimen interaction processes, and the advances in detector technology all played a major role in achieving the goal of atomic-resolution STEM imaging of practical materials. It is clear that tremendous advances in computer technology and electronics, image acquisition and processing algorithms, image simulations, and precision machining synergistically made atomic-resolution STEM imaging routinely accessible. It is anticipated that further hardware/software development is needed to achieve three-dimensional atomic-resolution STEM imaging with single-atom chemical sensitivity, even for electron-beam-sensitive materials. Artificial intelligence, machine learning, and big-data science are expected to significantly enhance the impact of STEM and associated techniques on many research fields such as materials science and engineering, quantum and nanoscale science, physics and chemistry, and biology and medicine. This review focuses on advances of STEM imaging from the invention of the field-emission electron gun to the realization of aberration-corrected and monochromated atomic-resolution STEM and its broad applications.
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Affiliation(s)
- Jingyue Jimmy Liu
- Department of Physics, Arizona State University, Tempe, AZ85287, USA
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O'Leary CM, Martinez GT, Liberti E, Humphry MJ, Kirkland AI, Nellist PD. Contrast transfer and noise considerations in focused-probe electron ptychography. Ultramicroscopy 2020; 221:113189. [PMID: 33360480 DOI: 10.1016/j.ultramic.2020.113189] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 09/24/2020] [Accepted: 11/30/2020] [Indexed: 11/26/2022]
Abstract
Electron ptychography is a 4-D STEM phase-contrast imaging technique with applications to light-element and beam-sensitive materials. Although the electron dose (electrons incident per unit area on the sample) is the primary figure of merit for imaging beam-sensitive materials, it is also necessary to consider the contrast transfer properties of the imaging technique. Here, we explore the contrast transfer properties of electron ptychography. The contrast transfer of focused-probe, non-iterative electron ptychography using the single-side-band (SSB) method is demonstrated experimentally. The band-pass nature of the phase-contrast transfer function (PCTF) for SSB ptychography places strict limitations on the probe convergence semi-angles required to resolve specific sample features with high contrast. The PCTF of the extended ptychographic iterative engine (ePIE) is broader than that for SSB ptychography, although when both high and low spatial frequencies are transferred, band-pass filtering is required to remove image artefacts. Normalisation of the transfer function with respect to the noise level shows that the transfer window is increased while avoiding noise amplification. Avoiding algorithms containing deconvolution steps may also increase the dose-efficiency of ptychographic phase reconstructions.
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Affiliation(s)
- Colum M O'Leary
- Department of Materials, University of Oxford, Parks Rd, Oxford OX13PH, United Kingdom.
| | - Gerardo T Martinez
- Department of Materials, University of Oxford, Parks Rd, Oxford OX13PH, United Kingdom
| | - Emanuela Liberti
- Department of Materials, University of Oxford, Parks Rd, Oxford OX13PH, United Kingdom; electron Physical Science Imaging Centre (ePSIC), Diamond Light Source, Didcot OX11 0DE, United Kingdom
| | - Martin J Humphry
- Phase Focus Ltd, Electric Works, Sheffield Digital Campus, Sheffield S1 2BJ, United Kingdom
| | - Angus I Kirkland
- Department of Materials, University of Oxford, Parks Rd, Oxford OX13PH, United Kingdom; electron Physical Science Imaging Centre (ePSIC), Diamond Light Source, Didcot OX11 0DE, United Kingdom; The Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot OX11 0FA, United Kingdom
| | - Peter D Nellist
- Department of Materials, University of Oxford, Parks Rd, Oxford OX13PH, United Kingdom
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Pennycook TJ, Yang H, Jones L, Cabero M, Rivera-Calzada A, Leon C, Varela M, Santamaria J, Nellist PD. 3D elemental mapping with nanometer scale depth resolution via electron optical sectioning. Ultramicroscopy 2016; 174:27-34. [PMID: 28012372 DOI: 10.1016/j.ultramic.2016.12.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 11/23/2016] [Accepted: 12/02/2016] [Indexed: 10/20/2022]
Abstract
Electron energy loss spectroscopy in the scanning transmission electron microscope has long been used to perform elemental mapping but has not previously exhibited depth sensitivity. The key to depth resolution with optical sectioning is the transfer of sufficiently high lateral spatial frequencies. By performing spectrum imaging with atomic resolution we achieve nanometer scale depth resolution, enabling us to optically section an oxide heterostructure spectroscopically. Such 3D elemental mapping is sensitive to atomic scale changes in structure and composition and is more interpretable than Z-contrast imaging alone.
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Affiliation(s)
- Timothy J Pennycook
- EPSRC SuperSTEM Facility, Daresbury Laboratory, Warrington WA4 4AD, UK; Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
| | - Hao Yang
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
| | - Lewys Jones
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
| | - Mariona Cabero
- Grupo de Fisica de Materiales Complejos, Universidad Complutense, 28040 Madrid, Spain
| | | | - Carlos Leon
- Grupo de Fisica de Materiales Complejos, Universidad Complutense, 28040 Madrid, Spain
| | - Maria Varela
- Grupo de Fisica de Materiales Complejos, Universidad Complutense, 28040 Madrid, Spain; Materials Science & Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Jacobo Santamaria
- Grupo de Fisica de Materiales Complejos, Universidad Complutense, 28040 Madrid, Spain
| | - Peter D Nellist
- EPSRC SuperSTEM Facility, Daresbury Laboratory, Warrington WA4 4AD, UK; Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
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Jones L, Nellist PD. Testing the accuracy of the two-dimensional object model in HAADF STEM. Micron 2014; 63:47-51. [DOI: 10.1016/j.micron.2013.12.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 12/10/2013] [Accepted: 12/17/2013] [Indexed: 11/28/2022]
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