Ultramicroscopy最新文献

{"title":"Experimental study of energy-dependent angular broadening of MeV electron beams for high-resolution imaging in thick samples","authors":"Xi Yang ,&nbsp;Paul Denham ,&nbsp;Atharva Kulkarni ,&nbsp;Brian Schaap ,&nbsp;Victor Smaluk ,&nbsp;Tianyi Wang ,&nbsp;Nathalie Bouet ,&nbsp;Mourad Idir ,&nbsp;Pietro Musumeci","doi":"10.1016/j.ultramic.2025.114260","DOIUrl":"10.1016/j.ultramic.2025.114260","url":null,"abstract":"<div><div>In scanning transmission electron microscopy (STEM), spatial resolution is primarily influenced by the projected size of the electron probe within the specimen. In thin samples, a large semi-convergence angle enables a tightly focused beam and sub-nanometer resolution. However, in thick specimens, resolution is fundamentally limited by transverse beam broadening from multiple large-angle scattering events—for example, a probe with 10 mrad angular divergence can broaden by ∼100 nm over a 10 μm path. Since this broadening scales inversely with beam energy, MeV-STEM offers a promising route for high-resolution imaging in thick materials. To quantitatively assess this effect, we performed high-precision measurements at UCLA’s PEGASUS beamline, characterizing beam divergence and intensity profiles for 3–8 MeV electrons transmitted through a wedged-silicon sample of varying thickness. Our results reconcile discrepancies among analytical models and validate Monte Carlo simulations. We find that increasing beam energy from 3.0 to 5.8 MeV reduces angular broadening by a factor of 2.6, with diminishing returns observed at 7.6 MeV. These findings provide a quantitative framework for optimizing MeV-STEM parameters in high-resolution imaging of thick biological and microelectronic specimens, and for guiding beam energy selection in other advanced imaging modes beyond STEM.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"279 ","pages":"Article 114260"},"PeriodicalIF":2.0,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Laser-induced electron beam emission from titanium dioxide on silicon photocathodes treated with cesium and barium oxide","authors":"C.W. Johnson ,&nbsp;L. Hess ,&nbsp;J. Schwede ,&nbsp;A. Stibor","doi":"10.1016/j.ultramic.2025.114249","DOIUrl":"10.1016/j.ultramic.2025.114249","url":null,"abstract":"<div><div>Electron beam sources are essential for a wide range of applications, including microscopy, high-energy physics, quantum science, spectroscopy, interferometry or sensors technology. However, conventional electron sources face critical limitations in energy spread, beam current, and stability, underscoring the need for advancements. In this study, we present and characterize a laser-stimulated electron beam source based on a titanium dioxide (TiO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>) surface on n-type doped silicon, coated with cesium (Cs) and barium oxide (BaO) to reduce the work function. This approach harnesses the surface photovoltage (SPV) phenomenon in an n-type semiconductor, wherein laser activation drives charge drift toward the surface, reducing band bending and further lowering the work function. The electrons are then extracted through low-voltage field emission. This mechanism is in contrast to established sources that rely on direct laser excitation through multi-photon absorption. Experimental investigations were conducted using a low-energy electron microscope (LEEM) and a custom field emitter characterization setup. By illuminating the TiO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> sample with laser wavelengths of 830 nm, 404 nm and 824 nm, and applying biased field emission between −35 and −100 eV, we achieved work functions below 1 eV, highly sensitive to surface preparation. The results demonstrate beam currents up to 30 nA, a clearly defined two-peak energy spectrum, and an energy distribution as narrow as 100 meV in the primary peak. These findings establish SPV as a promising alternative for generating electron beams with high current and narrow energy distributions, paving the way for innovative field emitter designs and applications.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"279 ","pages":"Article 114249"},"PeriodicalIF":2.0,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145347566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation study of the performance of neural network-enhanced PACBED for characterizing atomic-scale deformations in 2D van der Waals materials","authors":"Andrew B. Yankovich ,&nbsp;Magnus Röding ,&nbsp;Eva Olsson","doi":"10.1016/j.ultramic.2025.114246","DOIUrl":"10.1016/j.ultramic.2025.114246","url":null,"abstract":"<div><div>Two dimensional (2D) van der Waals (vdW) materials have attractive mechanical, electronic, optical, and catalytic properties that are highly tunable especially when they are thin. However, they are rarely perfect and flat, and their properties are strongly influenced by local crystal lattice deformations that include the 2D strain tensor, in-plane rotation and corrugation, where the latter is manifested as local sample tilt. Therefore, to gain more control over their properties, a detailed understanding of these deformations is needed. Position averaged convergent beam electron diffraction (PACBED) is a powerful technique for providing information about local atomic structure. In this work, we perform a comprehensive simulation study of the performance of PACBED in combination with convolutional neural networks (CNNs) for prediction of deformations of 2D materials. We generate around 100,000 simulated PACBED patterns from 2H MoS<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> for thicknesses from 1 to 20 atomic layers where strain, rotation, and tilt parameters are varied. Five convergence angles are explored which vary from conventional nano beam electron diffraction (6.35 mrad) to atomic resolution conditions (32.94 mrad). From this simulated PACBED library, we train regression CNNs to simultaneously predict the 2D strain tensor, in-plane rotation, and tilt of the sample. For different convergence angles and thicknesses, we study the prediction performance for each of the deformation parameters. We find that there is a trade-off between better prediction performance (small convergence angles) and probe size (large convergence angles). For smaller convergence angles like those used for conventional NBED conditions, the strain prediction error can be as low as 0.0003 %, while for larger convergence angles like those used for atomic resolution probes, the strain error increases to 0.001 - 0.003 %. The impressive prediction performance even for large convergence angles suggests that PACBED combined with CNNs is a feasible method for predicting deformation parameters using atomic resolution electron probes. Further, we conclude that the prediction can be difficult for monolayers, and suggest two remedies: excluding tilt from the predictions and performing nonlinear intensity rescaling of the training data. This work contributes to the optimal design of PACBED experiments for characterization of local crystal deformations and, therefore, to an improved understanding of how 2D vdW materials respond to imperfections.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"279 ","pages":"Article 114246"},"PeriodicalIF":2.0,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultra-thin plan-view lamella made by focused ion beam","authors":"Mengkun Tian ,&nbsp;Jingli Cheng ,&nbsp;Nashrah Afroze ,&nbsp;Yichen Yang ,&nbsp;Asif Khan ,&nbsp;Josh Kacher","doi":"10.1016/j.ultramic.2025.114250","DOIUrl":"10.1016/j.ultramic.2025.114250","url":null,"abstract":"<div><div>Understanding and controlling microstructure is critical for a wide range of functional materials, where properties such as ferroelectricity, conductivity, and catalytic activity are tightly coupled to nanoscale features like grain size, phase distribution, and interfaces. However, rigorous microstructural characterization is often hindered by the ultrathin geometries, nanocrystalline domains, and structural polymorphism inherent to these materials. Hafnium zirconium oxide (Hf₀.₅Zr₀.₅O₂, HZO) is an exemplar case: a leading ferroelectric oxide for next-generation embedded memory, storage and DRAM like applications, whose performance is strongly microstructure-dependent. Among available techniques, transmission electron microscopy (TEM) provides the most direct access to HZO’s nanometer-scale structure—TEM imaging reveals grain morphology, while nanobeam electron diffraction (NBED) distinguishes among its subtle polymorphs. However, conventional cross-sectional focused-ion-beam (FIB) lamellae often obscure such details due to limited field of view and through-thickness grain overlap. In contrast, plan-view lamellae isolate the target ultrathin film, enabling single-grain NBED and large-area imaging. In this study, we detail a refined focused-ion-beam (FIB) workflow for producing electron-transparent, plan-view lamellae from ∼10 nm-thick HZO films grown on Si substrates. The pivotal step is a low-kV fine-thinning sequence designed to maximize the preserved HZO area while minimizing ion-induced damage. This progress is tracked in situ by monitoring contrast changes in the scanning electron microscope (SEM) and verified ex situ with energy-dispersive X-ray spectroscopy (EDS). Referenced to an adjacent unthinned region, quantitative scanning transmission electron microscopy (STEM) imaging combined with EDS confirms a reproducible taper from the native 10 nm thickness to 3–4 nm at the lamella edge, all while maintaining atomic-column integrity. This workflow enables unambiguous polymorph identification and provides a robust platform for correlating microstructure with ferroelectric functionality in HZO and related ultrathin oxides—an essential step toward evaluating the performance of fluorite-based ferroelectric devices.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"279 ","pages":"Article 114250"},"PeriodicalIF":2.0,"publicationDate":"2025-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145270611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Imaging domain boundaries of rubrene thin crystallites by photoemission electron microscopy","authors":"Moha Naeimi,&nbsp;Katharina Engster,&nbsp;Waqas Pervez,&nbsp;Ingo Barke,&nbsp;Sylvia Speller","doi":"10.1016/j.ultramic.2025.114239","DOIUrl":"10.1016/j.ultramic.2025.114239","url":null,"abstract":"<div><div>The progress of designing organic semiconductors is extensively dependent on the quality of prepared organic molecular assemblies, since the charge transport mechanism is strongly efficient in highly ordered crystals compared to amorphous domains. Here we present a comprehensive photoemission electron microscopy (PEEM) and time-of-flight (TOF) spectroscopic study of rubrene (<span><math><mrow><msub><mrow><mi>C</mi></mrow><mrow><mn>48</mn></mrow></msub><msub><mrow><mi>H</mi></mrow><mrow><mn>24</mn></mrow></msub></mrow></math></span>) thin crystals focusing on recently developed orthorhombic crystalline morphologies applied in organic electronic devices. Using femtosecond pulsed lasers with photon energies between 3–6 eV, we explore the interplay between photoemission processes, crystal morphology, and defect states. In a 2-photon photoemission process (2PPE), the PEEM images reveal dominant emission localized at domain boundaries, indicating strong contributions from trap states. In contrast, in 1PPE nm excitation uniform emission across the crystal surface is observed, highlighting a fundamental difference in photoemission mechanisms. Furthermore, in the intermediate photon energy range, we identify a nonlinear, non-integer photon order, where mostly the triclinic morphology contributes to the emission, distinguishing it from the orthorhombic phase. These findings provide a new framework for assessing the quality and internal structure of organic semiconductor thin films via wavelength-dependent photoemission imaging and spectroscopy.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"279 ","pages":"Article 114239"},"PeriodicalIF":2.0,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145223593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Workflows for multimodal electron tomography using EELS and EDX and their application to a spinodally decomposed CuNiFe alloy","authors":"Tatiana Kormilina ,&nbsp;Georg Haberfehlner ,&nbsp;Thomas Mairhofer (Radlinger) ,&nbsp;Ferdinand Hofer ,&nbsp;Gerald Kothleitner","doi":"10.1016/j.ultramic.2025.114247","DOIUrl":"10.1016/j.ultramic.2025.114247","url":null,"abstract":"<div><div>Spectroscopic electron tomography using EDX and EELS signals presents significant challenges in both data acquisition and processing, particularly when aiming for high-fidelity 3D reconstructions. In this work, we present complete workflows that address these challenges through scripting-based solutions for automated parallel acquisition of EDX and EELS tilt series on the same microscope, as well as post-processing methods for correlating datasets acquired on different instruments. We demonstrate the advantages of a multimodal joint reconstruction, especially for undersampled or noisy data, where the combination of signals improves the reconstruction quality and enables lower-dose acquisition strategies. The developed workflows are applied to a spinodal CuNiFe alloy sample with inherently low HAADF contrast, successfully resolving ambiguities in the structure of nanoscale precipitates.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"279 ","pages":"Article 114247"},"PeriodicalIF":2.0,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145245382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Growth and oxidation of ultra-thin Pt-Sn layers on Pt(111) by molecular and atomic oxygen","authors":"N. Braud ,&nbsp;L. Buß ,&nbsp;L. Merte ,&nbsp;H. Wallander ,&nbsp;J.-O. Krisponeit ,&nbsp;T. Schmidt ,&nbsp;E. Lundgren ,&nbsp;J.I. Flege ,&nbsp;J. Falta","doi":"10.1016/j.ultramic.2025.114243","DOIUrl":"10.1016/j.ultramic.2025.114243","url":null,"abstract":"<div><div>The preparation of ultra-thin PtSn-alloyed layers by molecular beam epitaxy was studied using low-energy electron microscopy (LEEM) and micro-diffraction (<span><math><mi>μ</mi></math></span>-LEED). Deposition at a sample temperature of 435 °C initially results in the formation of a Pt<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>Sn/Pt(111) layer showing a (2 × 2) reconstruction. With continued Sn deposition, a Pt<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>Sn/Pt(111) layer develops, showing a (<span><math><mrow><msqrt><mrow><mn>3</mn></mrow></msqrt><mo>×</mo><msqrt><mrow><mn>3</mn></mrow></msqrt></mrow></math></span>)R30° reconstruction. An ultra-thin tin oxide was formed from the (2 × 2) surface by exposure to molecular oxygen at temperatures of 500 °C and 590 °C, respectively. LEED shows the evolution of a new surface structure, which could be identified as an incommensurate rectangular <span><math><mfenced><mrow><mtable><mtr><mtd><mn>2</mn><mo>.</mo><mn>3</mn></mtd><mtd><mn>0</mn></mtd></mtr><mtr><mtd><mn>1</mn><mo>.</mo><mn>8</mn></mtd><mtd><mn>3</mn><mo>.</mo><mn>6</mn></mtd></mtr></mtable></mrow></mfenced></math></span> reconstruction with lattice parameters of a = (6.4 ± 0.1)<!--> <!-->Å <!--> <!-->and b = (8.6 ± 0.1)<!--> <!-->Å <!--> <!-->present in three domains rotated by 120° with respect to each other. This structure can be related to the zigzag reconstructions found for similar ultra-thin oxide systems. Contrarily, the (<span><math><mrow><msqrt><mrow><mn>3</mn></mrow></msqrt><mspace></mspace><mo>×</mo><mspace></mspace><msqrt><mrow><mn>3</mn></mrow></msqrt></mrow></math></span>)R30° structure showed no oxide formation even after extensive exposure to molecular oxygen. The usage of atomic oxygen, however, allows for oxidation of this surface and the growth of thicker oxides on both types of overlayers. At 500 °C this process is accompanied by substantial roughening of the surface.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"278 ","pages":"Article 114243"},"PeriodicalIF":2.0,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145207755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating the convergence properties of iterative ptychography for atomic-resolution low-dose imaging","authors":"Tamazouzt Chennit ,&nbsp;Songge Li ,&nbsp;Hoelen L. Lalandec Robert ,&nbsp;Christoph Hofer ,&nbsp;Nadine J. Schrenker ,&nbsp;Liberato Manna ,&nbsp;Sara Bals ,&nbsp;Timothy J. Pennycook ,&nbsp;Jo Verbeeck","doi":"10.1016/j.ultramic.2025.114245","DOIUrl":"10.1016/j.ultramic.2025.114245","url":null,"abstract":"<div><div>This study investigates the convergence properties of a collection of iterative electron ptychography methods, under low electron doses (<span><math><mrow><mo>&lt;</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>3</mn></mrow></msup></mrow></math></span> <span><math><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>/</mo><msup><mrow><mtext>Å</mtext></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span>) and gives particular attention to the impact of the user-defined update strengths. We demonstrate that carefully chosen values for this parameter, ideally smaller than those conventionally met in the literature, are essential for achieving accurate reconstructions of the projected electrostatic potential. Using a 4D dataset of a thin hybrid organic–inorganic formamidinium lead bromide (FAPbBr₃) sample, we show that convergence is in practice achievable only when the update strengths for both the object and probe are relatively small compared to what is found in literature. Additionally we demonstrate that under low electron doses, the reconstructions initial error increases when the update strength coefficients are reduced below a certain threshold emphasizing the existence of critical values beyond which the algorithms are trapped in local minima. These findings highlight the need for carefully optimized reconstruction parameters in iterative ptychography, especially when working with low electron doses, ensuring both effective convergence and correctness of the result.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"278 ","pages":"Article 114245"},"PeriodicalIF":2.0,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145186736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-Resolution EELS in an aberration-corrected LEEM: Design of electrostatic transfer lenses for hemispherical filters","authors":"Vincent Lemelin,&nbsp;Richard Martel","doi":"10.1016/j.ultramic.2025.114238","DOIUrl":"10.1016/j.ultramic.2025.114238","url":null,"abstract":"<div><div>Recent advances in Low-Energy Electron Microscopy (LEEM), including the development of aberration-corrected (AC) systems, have significantly enhanced spatial resolution. However, further progress is limited by the energy resolution of current instruments. In this work, we propose a novel approach to address this limitation by integrating two Hemispherical Deflector Analyzers (HDAs) in tandem: the first serving to monochromatize the electron source, and the second to enhance the spectroscopic performance of AC-LEEM for Electron Energy Loss Spectroscopy (EELS). This dual-HDA configuration provides a clear pathway toward combining high spatial and energy resolution, expanding the capabilities of LEEM for advanced surface and materials characterization. This paper discusses various criteria for implementing these HDAs on a commercial AC-LEEM and presents more specifically the design of four transfer lenses (TLs) for electron transfer between the HDAs and the other optical components of the instrument. The use of a natural aberration correction scheme based on the dispersion-compensation (DC) principle is also discussed for maximum current throughput. Using ray-tracing simulations, we first show that the TL design can effectively decelerate/accelerate the electrons between 0.1 and 15 keV, thus respecting the high-voltage operation of the AC-LEEM. A double focus of the electron beam is also simulated so that the electron positions are conserved after transfer at the exit/entrance of the HDAs, an important condition for DC operation. Finally, ray-tracing simulations of the TLs show that the focal plane can be switched from the image plane to the back focal plane, allowing fast switching between diffraction and imaging modes.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"278 ","pages":"Article 114238"},"PeriodicalIF":2.0,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145099911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating atomic counts in metal nanoclusters via scanning transmission electron microscopy","authors":"Keizo Tsukamoto ,&nbsp;Naoyuki Hirata ,&nbsp;Masahide Tona ,&nbsp;Yoshihiro Nemoto ,&nbsp;Atsushi Nakajima","doi":"10.1016/j.ultramic.2025.114242","DOIUrl":"10.1016/j.ultramic.2025.114242","url":null,"abstract":"<div><div>Nanoscale metal atom aggregates, metal nanoclusters (NCs), exhibit unique electronic properties that strongly depend on the number of constituent atoms. Precise control over atomic composition is highly anticipated to advance NC-based materials science, particularly for fine-tuning photonic responses, catalytic reactivity, and electronic spin characteristics. In this study, we employed high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) to observe platinum (Pt) NCs immobilized on a substrate, enabling direct visualization of their deposition states, densities, and structures. The Pt NCs, containing 19 to 70 atoms with single-atom precision, were deposited onto TEM grids. By analysing STEM images, structural information indicative of a spherical shape was revealed, demonstrating a clear correlation between the number of atoms in Pt NCs and their observed diameters in the STEM, comparable to mass spectrometry assessments. This approach highlights estimation of the number of constituent atoms in metal NCs based on diameter distributions observed by STEM, providing valuable insight for size-dependent structural analysis and the exploration of their functionalized metal NCs.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"278 ","pages":"Article 114242"},"PeriodicalIF":2.0,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145151102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}