Ultramicroscopy最新文献

{"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":"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}

{"title":"ETDMS: Efficient two-stage diffusion model for accelerated SEM image super-resolution","authors":"Xuecheng Zhang ,&nbsp;Zixin Li ,&nbsp;Bin Zhang ,&nbsp;Wenchao Meng ,&nbsp;Yuefei Zhang ,&nbsp;Chaojie Gu ,&nbsp;Xianjue Ye ,&nbsp;Ze Zhang","doi":"10.1016/j.ultramic.2025.114226","DOIUrl":"10.1016/j.ultramic.2025.114226","url":null,"abstract":"<div><div>The scanning electron microscope (SEM) is a crucial tool for characterizing material microstructures, and it is renowned for its high resolution and depth of field. However, SEM image quality is affected by the scanning speed and resolution settings. When using SEM to capture fast-changing dynamic processes and other specific tasks, maintaining high image quality while using fast scanning mode is often tricky. To address these challenges, this paper introduces introduce an efficient two-stage diffusion model for accelerated SEM image super-resolution named ETDMS. The image denoising and super-resolution were divided into independent tasks based on SEM imaging principles and completed in two separate stages. Specifically, in Stage 2, a conditional lightweight encoder–decoder architecture SR network is proposed to replace the large U-Net in the traditional diffusion model and combine it with accelerated sampling technology to improve image generation efficiency. Experimental results prove that compared with previous super-resolution methods, the images generated by ETDMS significantly improve evaluation parameters, subjective visual quality, and detail generation.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"278 ","pages":"Article 114226"},"PeriodicalIF":2.0,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145109249","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":"Electron spin resonance spectroscopy in a transmission electron microscope","authors":"Antonín Jaroš ,&nbsp;Johann Toyfl ,&nbsp;Andrea Pupić ,&nbsp;Benjamin Czasch ,&nbsp;Giovanni Boero ,&nbsp;Isobel C. Bicket ,&nbsp;Philipp Haslinger","doi":"10.1016/j.ultramic.2025.114224","DOIUrl":"10.1016/j.ultramic.2025.114224","url":null,"abstract":"<div><div>Coherent spin resonance methods such as nuclear magnetic resonance (NMR) and electron spin resonance (ESR) spectroscopy have led to spectrally highly sensitive, non-invasive quantum imaging techniques with groundbreaking applications in fields such as medicine, biology, and physics. Meanwhile, transmission electron microscopy (TEM) offers detailed investigations with sub-atomic resolution, but often inflicts significant radiation damage. Here we exploit synergies and report on an integration of ESR spectroscopy in a TEM. Our miniaturized ESR setup, optimized for microscopic sample sizes, is implemented on a standard TEM sample holder and leverages the strong magnetic field of the TEM polepiece to align and energetically separate spin states. This integration will facilitate <em>in situ</em> studies of spin systems and their dynamics, quantum materials, radicals, electrochemical reactions, and radiation damage — properties that have, until now, been difficult to access using conventional electron microscopic tools. Moreover, this development marks a significant technological advancement towards microwave-driven quantum spin studies with a highly controlled electron probe at the nanoscale.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"278 ","pages":"Article 114224"},"PeriodicalIF":2.0,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145092543","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":"Novel technique for aluminum thin film thickness measurement using top view SEM-EDX in conjunction with electron beam simulation and machine learning","authors":"Tahsinul Huq ,&nbsp;Yew Hoong Wong ,&nbsp;Joon Huang Chuah ,&nbsp;Chee-Keong Tan ,&nbsp;Shuye Zhang","doi":"10.1016/j.ultramic.2025.114237","DOIUrl":"10.1016/j.ultramic.2025.114237","url":null,"abstract":"<div><div>A novel method for determining aluminum thin film thickness using top view SEM and EDX measurements has been developed. Electron beam simulations are used as the reference training data to feed into a machine learning algorithm, which once trained can predict the thickness of the aluminum thin film from EDX characteristic x-ray count measurements for a set of three accelerating voltages. Unlike previous techniques which rely on a reference pure material sample or substrate signal to compare to, this method compares instead using ratios of EDX x-ray signals using different accelerating voltages. Since no substrate signal is required, the layer(s) below the aluminum thin film may be any material. High prediction accuracy was obtained for the training and test data for most data points, below 10 % for thicknesses above 40 nm on average, though some large errors remained. Investigation of the lateral dispersion of the incident electron beams showed that lateral dispersion increased with accelerating voltage. Since measurement of higher thicknesses requires higher accelerating voltages, the minimum feature size that can be accurately measured increases for higher thicknesses. Limitations include the requirement for aluminum to be the top layer, the requirement for consistency of beam current, low signal and excessive noise at low values of accelerating voltage, and the need to make many measurements at different voltages if the approximate range of the thin film thickness is not initially known.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"278 ","pages":"Article 114237"},"PeriodicalIF":2.0,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060957","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":"Substrate matters: Coupled phonon modes of a spherical particle on a substrate probed with EELS","authors":"Ka Yin Lee ,&nbsp;Elliot K. Beutler ,&nbsp;Tifany Q. Crisolo ,&nbsp;David J. Masiello ,&nbsp;Maureen J. Lagos","doi":"10.1016/j.ultramic.2025.114229","DOIUrl":"10.1016/j.ultramic.2025.114229","url":null,"abstract":"<div><div>Using vibrational electron energy loss spectroscopy (vib-EELS) combined with numerical modeling, we investigate the physical mechanisms governing the phonon coupling between a spherical particle sustaining multipolar surface phonon modes and an underlying thin film. Depending upon their dielectric composition, a variety of hybrid phonon modes arise in the EEL spectrum due to the interaction between polarization charges in the particle and film. Mirror charge effects and phonon mode hybridization are the active mechanisms acting on dielectric and metallic-type films, respectively. Processes beyond dipole-dipole interactions are required to describe the sphere-film coupling.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"278 ","pages":"Article 114229"},"PeriodicalIF":2.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060889","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":"A new EBSD indexing method with enhanced grain boundary indexing performance using a three-dimensional parameter space","authors":"Fan Peng ,&nbsp;Xuemei Song ,&nbsp;Yiling Huang ,&nbsp;Xingyu Jin ,&nbsp;Yuqing Jiang ,&nbsp;Yue Sun ,&nbsp;Yi Zeng","doi":"10.1016/j.ultramic.2025.114227","DOIUrl":"10.1016/j.ultramic.2025.114227","url":null,"abstract":"<div><div>Electron backscatter diffraction (EBSD) is an important technique based on the scanning electron microscope (SEM) that provides a wide range of crystallographic information. There are limited available pattern indexing methods and most of them are mastered by commercial instrument manufacturers, which may probably restrict the sharing and development of indexing techniques. In this study, we present a new EBSD pattern indexing method based on a three-dimensional parameter space. This method extends the characterization of characteristic triangles into a three-dimensional parameter space. This work details the procedure of the new indexing algorithm. The utility of this new method is demonstrated using experimental patterns captured from a cubic yttria-stabilized zirconia (YSZ) bulk sample. Compared with commercial indexing results, the new method shows excellent consistency and achieves better indexing performance at grain boundaries.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114227"},"PeriodicalIF":2.0,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144907275","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}