- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Accurate and efficient data acquisition methods for high-resolution angle-resolved photoemission microscopy
摘要： Angle-resolved photoemission spectroscopy (ARPES) is a powerful experimental technique in materials science, as it can directly probe electronic states inside solids in energy (E) and momentum (k) space. As an advanced technique, spatially-resolved ARPES using a well-focused light source (high-resolution ARPES microscopy) has recently attracted growing interests because of its capability to obtain local electronic information at micro- or nano-metric length scales. However, there exist several technical challenges to guarantee high precision in determining translational and rotational positions in reasonable measurement time. Here we present two methods of obtaining k-space mapping and real-space imaging in high-resolution ARPES microscopy. One method is for k-space mapping measurements that enables us to keep a target position on a sample surface during sample rotation by compensating rotation-induced displacements (tracing acquisition method). Another method is for real-space imaging measurements that significantly reduces total acquisition time (scanning acquisition method). We provide several examples of these methods that clearly indicate higher accuracy in k-space mapping as well as higher efficiency in real-space imaging, and thus improved throughput of high-resolution APRES microscopy.
关键词： k-space mapping,ARPES,real-space imaging,Angle-resolved photoemission spectroscopy,high-resolution ARPES microscopy
更新于2025-09-09 09:28:46
-
Molybdenum Disulfid: Differentiating Polymorphs in Molybdenum Disulfide via Electron Microscopy (Adv. Mater. 47/2018)
摘要： The presence of rich polymorphs and stacking polytypes in molybdenum disulfide (MoS2) endows it with a diverse range of properties. This has stimulated a lot of interest in the unique properties associated with each polymorph. In article number 1802397, Kian Ping Loh and co-workers discuss the use of electron microscopy for identifying the atomic structures of several important polymorphs in MoS2 and establishing the correlation between structure and properties.
关键词： polymorphs,electron microscopy,stacking polytypes,molybdenum disulfide,MoS2
更新于2025-09-09 09:28:46
-
Directional Sinogram Inpainting for Limited Angle Tomography
摘要： In this paper we propose a new joint model for the reconstruction of tomography data under limited angle sampling regimes. In many applications of Tomography, e.g. Electron Microscopy and Mammography, physical limitations on acquisition lead to regions of data which cannot be sampled. Depending on the severity of the restriction, reconstructions can contain severe, characteristic, artefacts. Our model aims to address these artefacts by inpainting the missing data simultaneously with the reconstruction. Numerically, this problem naturally evolves to require the minimisation of a non-convex and non-smooth functional so we review recent work in this topic and extend results to fit an alternating (block) descent framework. We perform numerical experiments on two synthetic datasets and one Electron Microscopy dataset. Our results show consistently that the joint inpainting and reconstruction framework can recover cleaner and more accurate structural information than the current state of the art methods.
关键词： Joint Model,Electron Microscopy,Limited Angle Tomography,Non-convex Optimization,Directional Sinogram Inpainting
更新于2025-09-09 09:28:46
-
Identification of Bacterial Diseases in Rice Plants Leaves by the Use of Spectroscopic Imaging
摘要： Rice is staple in the African habitats menu. Bacterial wilt (BLB) and leaf streak (BLS) are some of the phytopathological diseases which restrain rice production around the world. In this paper, multi-spectral and multi- modal imaging techniques have been developed to characterize the rice leaves with symptoms of bacterial wilt (BLB) and leaf streak (BLS), and to provide information on their effects, in order to reduce their spread. First, we recorded microscopic and spectroscopic images of the samples using multimodal and multispectral microscope, with spectral region ranging from UV to NIR, for each mode. Then, we extracted the spectral footprints of the cells constituents, in transmission, reflection and scattering from the spectral images. Applying multivariate statistical analysis methods to this optical spectra allowed us to characterize the effect of bacterial rice leaves caused by Xanthomonas oryzae strains. The results of the proposed technique can be useful for easy identification of this type of infection, and can serve as routine approach in biochemical and agronomic laboratories.
关键词： Xanthomonas oryzae,multispectral and multimodal microscopy,spectroscopic imaging,plant cell diseases,classification,rice
更新于2025-09-09 09:28:46
-
Electronic properties of Pb islands on graphene: Consequences of a weak interface coupling from a combined STM and <i>ab initio</i> study
摘要： By means of scanning tunneling microscopy and spectroscopy, we investigate the electronic properties of lead islands (width 5–100 nm, thickness 5–25 monolayers) deposited by molecular beam epitaxy on twisted graphene layers grown on SiC(000-1). We ?nd that elastic scattering processes govern the local density of states probed at the surface of the Pb islands, inducing (i) the well-known quantum well states due to electron con?nement in the direction perpendicular to the surface and (ii) spatial in-plane periodic modulations related to quasiparticle interferences off the island edges. Through a quantitative analysis of these effects, compared with ab initio calculations for a two-dimensional Pb slab, we conclude that the lead islands grown on the surface of graphene can be considered as freestanding from the point of view of their electronic structure, leaving the surrounding graphene layer unperturbed. Accordingly, low bias tunneling spectra show evidence of a sizable interface resistance. Nevertheless, we suggest that the transparency of the interface, which can be estimated from its resistance, is good enough to induce superconductivity within the underlying graphene layer by proximity effect with the Pb islands.
关键词： lead islands,graphene,quantum well states,quasiparticle interferences,interface resistance,superconductivity,scanning tunneling microscopy,proximity effect,spectroscopy
更新于2025-09-09 09:28:46
-
[IEEE 2018 IEEE 15th International Symposium on Biomedical Imaging (ISBI 2018) - Washington, DC (2018.4.4-2018.4.7)] 2018 IEEE 15th International Symposium on Biomedical Imaging (ISBI 2018) - Segmentation of cell nuclei using intensity-based model fitting and sequential convex programming
摘要： We introduce a convex model-based approach for the segmentation of cell nuclei, which exploits both shape and intensity information. The model is directly fitted to the image intensities. Previous shape-based approaches either are not globally optimal or require prior binarization of an image. Our approach relies on a fast second-order optimization scheme to solve a sequence of convex programs and estimate the globally optimal solution based on the image intensities. Model fitting is performed within image regions which are determined by exploiting the local image structure. We evaluated our approach using fluorescence microscopy images of two different cell types and performed a quantitative comparison with previous methods.
关键词： model fitting,Fluorescence microscopy,convex optimization,cell segmentation
更新于2025-09-09 09:28:46
-
[IEEE 2017 IEEE Workshop on Recent Advances in Photonics (WRAP) - Hyderabad (2017.12.18-2017.12.19)] 2017 IEEE Workshop on Recent Advances in Photonics (WRAP) - High Resolution and Wide Field Microscopy Using Fourier Ptychography and Flatbed Scanner
摘要： We report the development of high resolution and wide field of view microscopy using a programmable 8X8 LED array and a flatbed scanner. The LEDs are illuminated sequentially and analyzed using Fourier Ptychography algorithm to generate high resolution image of the sample.
关键词： Phase retrival,microscopy,computational imaging
更新于2025-09-09 09:28:46
-
A Scanning Tunneling Microscopy Study of Monolayer and Bilayer Transition-Metal Dichalcogenides Grown by Molecular-Beam Epitaxy
摘要： This review presents an account of some recent scanning tunneling microscopy and spectroscopy (STM/S) studies of monolayer and bilayer transition-metal dichalcogenide (TMD) films grown by molecular-beam epitaxy (MBE). In addition to some intrinsic properties revealed by STM/S, defects such as inversion domain boundaries and point defects, their properties and induced effects, are presented. More specifically, the quantum confinement and moiré potential effects, charge state transition, quasi-particle interference and structural phase transition as revealed by STM/S are described.
关键词： transition-metal dichalcogenides,quantum confinement,structural phase transition,molecular-beam epitaxy,moiré potential,quasi-particle interference,scanning tunneling microscopy,charge state transition
更新于2025-09-09 09:28:46
-
Single-shot Real-time Sub-nanosecond Electron Imaging Aided by Compressed Sensing: Analytical Modeling and Simulation
摘要： Bringing ultrafast (nanosecond and below) temporal resolution to transmission electron microscopy (TEM) has historically been challenging. Despite significant recent progress in this direction, it remains difficult to achieve sub-nanosecond temporal resolution with a single electron pulse, in real-time (i.e., duration in which the event occurs) imaging. To address this limitation, here, we propose a methodology that combines laser-assisted TEM with computational imaging methodologies based on compressed sensing (CS). In this technique, a two-dimensional (2D) transient event [i.e. (??, ??) frames that vary in time] is recorded through a CS paradigm, which consists of spatial encoding, temporal shearing via streaking, and spatiotemporal integration of an electron pulse. The 2D image generated on a camera is used to reconstruct the datacube of the ultrafast event, with two spatial and one temporal dimensions, via a CS-based image reconstruction algorithm. Using numerical simulation, we find that the reconstructed results are in good agreement with the ground truth, which demonstrates the applicability of CS-based computational imaging methodologies to laser-assisted TEM. Our proposed method, complementing the existing ultrafast stroboscopic and nanosecond single-shot techniques, opens up the possibility for single-shot, real-time, spatiotemporal imaging of irreversible structural phenomena with sub-nanosecond temporal resolution.
关键词： ultrafast imaging,compressed sensing,streak imaging,transmission electron microscopy
更新于2025-09-09 09:28:46
-
Nanoscale Imaging of Kidney Glomeruli Using Expansion Pathology
摘要： Kidney glomerular diseases, such as the minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS), and other nephrotic syndromes, are typically diagnosed or confirmed via electron microscopy. Although optical microscopy has been a vital tool to examine clinical specimens for diagnoses in pathology for decades, the optical resolution is constricted by the physical diffraction limit of the optical microscope, which prevents high-resolution investigation of subcellular anatomy, such as of the podocyte tertiary foot processes. Here, we describe a simple, fast, and inexpensive protocol for nanoscale optical imaging of kidney glomeruli. The protocol is based on Expansion Pathology (ExPath), a new principle of microscopy that overcomes optical diffraction limit by chemically embedding specimens into a swellable polymer and physically expanding it homogenously prior to imaging. Our method uses only commercially available reagents, a conventional fluorescence microscope and it can be applied to both fixed-frozen or formalin-fixed paraffin embedded (FFPE) tissue sections. It requires minimal operative experience in a wet lab, optical microscopy and imaging processing. Finally, we also discuss challenges, limitations and prospective applications for ExPath-based imaging of glomeruli.
关键词： imaging,kidney glomerulus,immunostaining,expansion microscopy,tissue expansion,nanoscopy
更新于2025-09-09 09:28:46