Article
Chemistry, Physical
Radim Skoupy, Daan B. B. Boltje, Miroslav Slouf, Katerina Mrazova, Tomas Laznicka, Clemence M. Taisne, Vladislav Krzyzanek, Jacob P. P. Hoogenboom, Arjen J. J. Jakobi
Summary: This study presents a quantitative four-dimensional scanning transmission electron microscopy (4D-STEM) imaging technique (q4STEM) for local thickness estimation across amorphous specimens. The method measures spatially resolved diffraction patterns and evaluates the angular distribution of electron scattering or the ratio of integrated virtual dark and bright field STEM signals using Monte Carlo simulations. The method is independent of signal intensity calibrations and only requires knowledge of the detector geometry. The results demonstrate that the method yields robust thickness estimates for sub-micrometer amorphous specimens in different detectors and instruments.
Article
Chemistry, Multidisciplinary
Yi Wen, Shiang Fang, Matthew Coupin, Yang Lu, Colin Ophus, Efthimios Kaxiras, Jamie H. Warner
Summary: Four-dimensional (4D) scanning transmission electron microscopy was used to study the electric fields at the edges of 2D semiconducting monolayer MoS2. Sub-nanometer 1D features in the 2D electric field maps were observed at the outermost region along zigzag edges and also along nanowire MoS-terminated MoS2 edges. The presence of low Z number atoms terminating many of the uniform edges was revealed through electric field reconstructions, along with integrated differential phase contrast reconstructions. Density functional theory calculations supported the formation of periodic 1D edge states and indicated the enhancement of electric field magnitude for some edge terminations. The experimentally observed electric fields at the edges were attributed to the absence of an opposing electric field from a nearest neighbor atom when the electron beam propagates through the 2D monolayer and interacts. These results highlight the potential of 4D-STEM in mapping the atomic scale structure and fluctuations of electric fields around edge atoms in 2D materials.
Article
Chemistry, Multidisciplinary
Yichao Zhang, David J. Flannigan
Summary: This study demonstrates the direct observation of ultrafast atomic-to-nanoscale lattice dynamics at individual surface steps using femtosecond 4D ultrafast electron microscopy, revealing nanometer-variant softening of photoexcited phonons. The softening effect is attributed to anisotropic bond dilation and photoinduced incoherent atomic displacements, extending laterally tens of nanometers from the atomic-scale discontinuity. The high spatiotemporal resolutions achieved in this study provide new insights into atomic-scale structure-function relationships of highly defect-sensitive, functional materials.
Article
Optics
Erzhuang Song, Qingchun Lei, Yeqing Chi, Yibin Xia, Wei Fan
Summary: This study aims to address two critical issues in 4D tomographic measurements: the accuracy of multi-camera calibration and the processing time of the tomographic program. A new multi-camera calibration method and a parallel tomographic reconstruction program have been developed, improving both accuracy and processing speed.
Article
Chemistry, Multidisciplinary
Matthew J. Coupin, Yi Wen, Sungwoo Lee, Anshul Saxena, Colin Ophus, Christopher S. Allen, Angus I. Kirkland, Narayana R. Aluru, Gun-Do Lee, Jamie H. Warner
Summary: Defects in crystalline lattices cause modulation of the atomic density, leading to variations in the associated electrostatics at the nanoscale. Four-dimensional scanning transmission electron microscopy (4D-STEM) was used to measure electric fields near point dislocations in a monolayer, overcoming the challenges of traditional phase contrast imaging. The increased electric field magnitude near the (1,0) edge dislocation core in graphene is shown to arise from long-range interactions beyond the nearest atomic neighbor. These results provide insights into using 4D-STEM for quantifying electrostatics and mapping potential variations in thin materials.
Article
Chemistry, Multidisciplinary
Sytze de Graaf, Majid Ahmadi, Ivan Lazic, Eric G. T. Bosch, Bart J. Kooi
Summary: STEM is the most commonly used tool for atomic scale characterization of two-dimensional materials, but damage-free imaging remains a challenge, especially when observing combinations of light and heavy elements, particularly when recording fast dynamic phenomena.
Article
Chemistry, Multidisciplinary
Jacob Smith, Zhennan Huang, Wenpei Gao, Guannan Zhang, Miaofang Chi
Summary: Cryogenic four-dimensional scanning transmission electron microscopy (4D-STEM) imaging is a valuable technique for studying quantum materials and their interfaces at atomic scale, but its applications are restricted by the instability of cryo-stages and electronics. To address this issue, an algorithm is developed to correct complex distortions in the atomic resolution cryogenic 4D-STEM data sets. This method involves nonrigid registration and affine transformations to minimize information loss in both reciprocal and real spaces, enabling the reconstruction of sample information from 4D-STEM data sets. It is computationally inexpensive, fast, and suitable for on-the-fly data analysis in future in situ cryogenic 4D-STEM experiments.
Article
Materials Science, Multidisciplinary
E. Thronsen, J. Frafjord, J. Friis, C. D. Marioara, S. Wenner, S. J. Andersen, R. Holmestad
Summary: A new methodology has been developed to study the fine details of GP zones in age-hardenable aluminium alloys. It combines high-resolution imaging with electron diffraction and simulations. The stability of the atomic models developed based on the experimental results was verified.
MATERIALS CHARACTERIZATION
(2022)
Article
Materials Science, Multidisciplinary
A. J. Santos, B. Lacroix, F. Maudet, F. Paumier, S. Hurand, C. Dupeyrat, V. J. Gomez, D. L. Huffaker, T. Girardeau, R. Garcia, F. M. Morales
Summary: This report provides an overview of the possibilities offered by applying various (S)TEM techniques for the study of nanostructured and porous photonic surfaces. Several working examples demonstrate the type of information that can be obtained, and advanced characterization techniques enable high-resolution imaging and spectroscopy at both microscopic and nanoscopic levels.
MATERIALS CHARACTERIZATION
(2022)
Article
Physics, Applied
C. S. Allen, M. Danaie, J. H. Warner, D. J. Batey, A. I. Kirkland
Summary: We demonstrate that electron ptychographic phase reconstruction can recover spatial frequencies higher than those directly recorded in the experimental electron diffraction patterns. This allows for the simultaneous recording of a conventional annular dark field image and a ptychographic dataset by inserting an annular detector that partially shadows a lower pixelated detector. We achieved an Abbe limited resolution of 1.2 +/- 0.1A degrees in our reconstructions of monolayer molybdenum disulfide at 30 keV.
APPLIED PHYSICS LETTERS
(2023)
Article
Multidisciplinary Sciences
Dehui Zhang, Zhen Xu, Zhengyu Huang, Audrey Rose Gutierrez, Cameron J. Blocker, Che-Hung Liu, Miao-Bin Lien, Gong Cheng, Zhe Liu, Il Yong Chun, Jeffrey A. Fessler, Zhaohui Zhong, Theodore B. Norris
Summary: In recent years, new approaches to optical imaging have rapidly evolved, with a focus on extracting three-dimensional information from traditionally two-dimensional image capture. The integration of transparent focal stack imaging systems using graphene photodetector arrays with advanced neural networks has enabled real-time 3D optical imaging and object tracking, showcasing promising new frontiers in imaging technology.
NATURE COMMUNICATIONS
(2021)
Editorial Material
Multidisciplinary Sciences
Nivedita Saxena, Michael Rendl
Summary: Combined imaging and gene-expression analyses have shown that the arrangement of cells in concentric rings in disc-like structures that form hair follicles can predetermine their fate and location in mature follicles.
Review
Optics
Longqian Huang, Ruichen Luo, Xu Liu, Xiang Hao
Summary: This article reviews state-of-the-art deep-learning-empowered computational spectral imaging methods, which possess fast reconstruction speed, excellent reconstruction quality, and the potential to reduce system volume significantly.
LIGHT-SCIENCE & APPLICATIONS
(2022)
Article
Agriculture, Dairy & Animal Science
Nicole Weingand, Johanna Vuille-dit-Bille, Rahel Jud Schefer, Annette P. N. Kutter, Martina Stirn, Katja-Nicole Adamik, Nadja E. Sigrist
Summary: This study investigates the influence of time on viscoelastic testing results and finds a tendency towards hypocoagulability over time. This finding is clinically significant for determining a patient's coagulation status.
Article
Robotics
Yuan Zhuang, Binliang Wang, Jianzhu Huai, Miao Li
Summary: This paper presents a real-time imaging radar inertial odometry and mapping method based on the submap concept. It utilizes millimeter wave radar to measure distances, directions, and Doppler velocity, as well as objects' height. The method leverages the rich data of imaging radars and robustly estimates ego-velocity from a single scan using the graduated non-convexity method. The scan-to-submap matches, along with 6D inertial data, are fused to obtain the platform's 3D position and orientation using an iterative extended Kalman filter. A loop closure module is developed to mitigate odometry drift.
IEEE ROBOTICS AND AUTOMATION LETTERS
(2023)