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Rez P. Does the order of elastic and inelastic scattering affect an image or is there a top bottom effect from inelastic scattering? Ultramicroscopy 2024; 257:113890. [PMID: 38113821 DOI: 10.1016/j.ultramic.2023.113890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 11/13/2023] [Accepted: 11/23/2023] [Indexed: 12/21/2023]
Abstract
Especially for light elements inelastic scattering is more probable than the elastic scattering that conveys the structural information. The question arises as to whether an image using inelastically scattered electrons is different depending on whether the elastic or inelastic scattering happens first, is there a top-bottom effect. We show that since inelastic scattering is concentrated in a narrow range of angles, much less than typical Bragg angles in light element materials, the inelastic and elastic processes are separable and, to a very good approximation, there is no top-bottom effect. For weakly scattering thin biological specimens that are phase objects the separation is exact and there can be no top-bottom effect.
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Affiliation(s)
- Peter Rez
- Department of Physics, Arizona State University, Tempe, AZ 85287-1504, USA.
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Liu S, Dong J, Ma Z, Hu W, Deng Y, Shi Y, Wang X, Qiu Y, Walther T. The evolution of indium precipitation in gallium focused ion beam prepared samples of InGaAs/InAlAs quantum wells under electron beam irradiation. J Microsc 2024; 293:169-176. [PMID: 38112123 DOI: 10.1111/jmi.13251] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 11/20/2023] [Accepted: 12/11/2023] [Indexed: 12/20/2023]
Abstract
Gallium ion (Ga+ ) beam damage induced indium (In) precipitation in indium gallium arsenide (InGaAs)/indium aluminium arsenide (InAlAs) multiple quantum wells and its corresponding evolution under electron beam irradiation was investigated by valence electron energy loss spectroscopy (VEELS) and high-angle annular dark-field imaging (HAADF) in scanning transmission electron microscopy (STEM). Compared with argon ion milling for sample preparation, the heavier projectiles of Ga+ ions pose a risk to trigger In formation in the form of tiny metallic In clusters. These are shown to be sensitive to electron irradiation and can increase in number and size under the electron beam, deteriorating the structure. Our finding reveals the potential risk of formation of In clusters during focused ion beam (FIB) preparation of InGaAs/InAlAs quantum well samples and their subsequent growth under STEM-HAADF imaging, where initially invisible In clusters of a few atoms can move and swell during electron beam exposure.
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Affiliation(s)
- Shuo Liu
- College of Electronic and Information, Southwest Minzu University, State Ethnic Affairs Commission, Chengdu, China
| | - Jiawei Dong
- College of Electronic and Information, Southwest Minzu University, State Ethnic Affairs Commission, Chengdu, China
| | - Zhenyu Ma
- College of Electronic and Information, Southwest Minzu University, State Ethnic Affairs Commission, Chengdu, China
| | - Wenyu Hu
- Pico Center, SUSTech Core Research Facilities, Southern University of Science and Technology, Shenzhen, China
| | - Yong Deng
- College of Electronic and Information, Southwest Minzu University, State Ethnic Affairs Commission, Chengdu, China
- Pico Center, SUSTech Core Research Facilities, Southern University of Science and Technology, Shenzhen, China
| | - Yuechun Shi
- Photon Technology Research Center, Yongjiang Laboratory, Ningbo, China
| | - Xiaoyi Wang
- College of Electronic and Information, Southwest Minzu University, State Ethnic Affairs Commission, Chengdu, China
| | - Yang Qiu
- Pico Center, SUSTech Core Research Facilities, Southern University of Science and Technology, Shenzhen, China
| | - Thomas Walther
- Department Electronic & Electrical Engineering, University of Sheffield, Sheffield, UK
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Cheng X, Wang C, Chen S, Zhang L, Liu Z, Zhang W. Preparation of MoS 2@PDA-Modified Polyimide Films with High Mechanical Performance and Improved Electrical Insulation. Polymers (Basel) 2024; 16:546. [PMID: 38399923 PMCID: PMC10893148 DOI: 10.3390/polym16040546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 02/04/2024] [Accepted: 02/05/2024] [Indexed: 02/25/2024] Open
Abstract
Polyimide (PI) has been widely used in cable insulation, thermal insulation, wind power protection, and other fields due to its high chemical stability and excellent electrical insulation and mechanical properties. In this research, a modified PI composite film (MoS2@PDA/PI) was obtained by using polydopamine (PDA)-coated molybdenum disulfide (MoS2) as a filler. The low interlayer friction characteristics and high elastic modulus of MoS2 provide a theoretical basis for enhancing the flexible mechanical properties of the PI matrix. The formation of a cross-linking structure between a large number of active sites on the surface of the PDA and the PI molecular chain can effectively enhance the breakdown field strength of the film. Consequently, the tensile strength of the final sample MoS2@PDA/PI film increased by 44.7% in comparison with pure PI film, and the breakdown voltage strength reached 1.23 times that of the original film. It can be seen that the strategy of utilizing two-dimensional (2D) MoS2@PDA nanosheets filled with PI provides a new modification idea to enhance the mechanical and electrical insulation properties of PI films.
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Affiliation(s)
- Xian Cheng
- School of Electrical and Information Engineering, Zhengzhou University, Zhengzhou 450001, China; (X.C.); (C.W.); (L.Z.); (Z.L.); (W.Z.)
- He’nan Engineering Research Center of Power Transmission and Distribution Equipment and Electrical Insulation, Zhengzhou 450001, China
| | - Chenxi Wang
- School of Electrical and Information Engineering, Zhengzhou University, Zhengzhou 450001, China; (X.C.); (C.W.); (L.Z.); (Z.L.); (W.Z.)
- He’nan Engineering Research Center of Power Transmission and Distribution Equipment and Electrical Insulation, Zhengzhou 450001, China
| | - Shuo Chen
- School of Electrical and Information Engineering, Zhengzhou University, Zhengzhou 450001, China; (X.C.); (C.W.); (L.Z.); (Z.L.); (W.Z.)
- He’nan Engineering Research Center of Power Transmission and Distribution Equipment and Electrical Insulation, Zhengzhou 450001, China
| | - Leyuan Zhang
- School of Electrical and Information Engineering, Zhengzhou University, Zhengzhou 450001, China; (X.C.); (C.W.); (L.Z.); (Z.L.); (W.Z.)
- He’nan Engineering Research Center of Power Transmission and Distribution Equipment and Electrical Insulation, Zhengzhou 450001, China
| | - Zihao Liu
- School of Electrical and Information Engineering, Zhengzhou University, Zhengzhou 450001, China; (X.C.); (C.W.); (L.Z.); (Z.L.); (W.Z.)
- He’nan Engineering Research Center of Power Transmission and Distribution Equipment and Electrical Insulation, Zhengzhou 450001, China
| | - Wenhao Zhang
- School of Electrical and Information Engineering, Zhengzhou University, Zhengzhou 450001, China; (X.C.); (C.W.); (L.Z.); (Z.L.); (W.Z.)
- He’nan Engineering Research Center of Power Transmission and Distribution Equipment and Electrical Insulation, Zhengzhou 450001, China
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Hayashida M, Yamasaki J, Malac M. Sample thickness affects contrast and measured shape in TEM images and in electron tomograms. Micron 2024; 177:103562. [PMID: 37992499 DOI: 10.1016/j.micron.2023.103562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 10/30/2023] [Accepted: 10/31/2023] [Indexed: 11/24/2023]
Abstract
We investigated the effect of nanoparticle (NP) image broadening and its contrast change dependence on a support matrix thickness in a transmission electron microscope (TEM). We measured the effect of NP size and atomic number on its image broadening. Based on the experimental TEM images we generated tomograms of NPs on four types of support matrix. The measured shape aspect ratio of the NPs in such tomograms depends on the geometry of the support matrix. For example, the aspect ratio of 6 nm NP placed on a thin film with window-frame support is 1.14, while the aspect ratio of 6 nm NP on a rod-shaped support with 910 nm diameter is 1.67 in a tomogram.
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Affiliation(s)
- Misa Hayashida
- NRC-NANO, National Research Council, Edmonton, Alberta T6G 2M9, Canada.
| | - Jun Yamasaki
- Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki 567-0047, Japan; Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8601, Japan
| | - Marek Malac
- NRC-NANO, National Research Council, Edmonton, Alberta T6G 2M9, Canada; Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
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Egerton RF. Voxel dose-limited resolution for thick beam-sensitive specimens imaged in a TEM or STEM. Micron 2024; 177:103576. [PMID: 38113715 DOI: 10.1016/j.micron.2023.103576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/09/2023] [Accepted: 12/10/2023] [Indexed: 12/21/2023]
Abstract
The resolution limit imposed by radiation damage is quantified in terms of a voxel dose-limited resolution (DLR), applicable to small features within a thick specimen. An analytical formula for this DLR is derived and applied to bright-field mass-thickness contrast from organic (polymer or biological) specimens of thickness between 400 nm and 20 µm. For a permissible dose of 330 MGy (typical of frozen-hydrated tissue), the TEM or STEM image resolution is determined by radiation damage rather than by lens aberrations or beam-broadening effects, which can be restricted by use of a small angle-limiting aperture. DLR is improved by a up to factor of 2 by increasing the primary-electron energy from 300 keV to 3 MeV, or by up to a factor of 3 by heavy-metal staining. For stained samples, a higher electron fluence allows better resolution but the improvement is modest because the voxel DLR is proportional to the 1/4 power of electron dose. The relevance of voxel and columnar DLR is discussed, for both thick and thin samples.
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Affiliation(s)
- R F Egerton
- Physics Department, University of Alberta, Edmonton T6G 2E1, Canada
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Huang C, Kim JS, Kirkland AI. Cryo-electron ptychography: Applications and potential in biological characterisation. Curr Opin Struct Biol 2023; 83:102730. [PMID: 37992450 DOI: 10.1016/j.sbi.2023.102730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 09/06/2023] [Accepted: 10/16/2023] [Indexed: 11/24/2023]
Abstract
There is a clear need for developments in characterisation techniques that provide detailed information about structure-function relationships in biology. Using electron microscopy to achieve high resolution while maintaining a broad field of view remains a challenge, particularly for radiation-sensitive specimens where the signal-to-noise ratio required to maintain structural integrity is limited by low electron fluence. In this review, we explore the potential of cryogenic electron ptychography as an alternative method for characterising biological systems under low-fluence conditions. Using this method with increased information content from multiple sampled regions of interest potentially allows 3D reconstruction with far fewer particles than required in conventional cryo-electron microscopy. This is important for achieving higher resolution in systems where distributions of homogeneous single particles are difficult to obtain. We discuss the progress, limitations, and potential areas for future development of this approach for both single particle analysis and applications to heterogeneous large objects.
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Affiliation(s)
- Chen Huang
- Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot, OX11 0QX, United Kingdom.
| | - Judy S Kim
- Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot, OX11 0QX, United Kingdom; Department of Materials, University of Oxford, Oxford, OX1 3PH, United Kingdom
| | - Angus I Kirkland
- Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot, OX11 0QX, United Kingdom; Department of Materials, University of Oxford, Oxford, OX1 3PH, United Kingdom
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