المؤلفون: Chang, C.T., Apsangi, P., Muthuseenu, K., Privat, A., Kennedy, B., McCartney, M.R., Smith, D.J., Holbert, K.E., Barnaby, H.J.

المصدر: IEEE Transactions on Nuclear Science IEEE Trans. Nucl. Sci. Nuclear Science, IEEE Transactions on. 71(4):585-590 Apr, 2024

المؤلفون: Burchert, Jan-Philipp, Frohn, Jasper, Rölleke, Ulrike, Bruns, Hendrik, Yu, Boram, Gleber, Sophie-Charlotte, Stange, Roland, Busse, Madleen, Osterhoff, Markus, Salditt, Tim, Köster, Sarah

المصدر: Journal of Synchrotron Radiation; Jul2024, Vol. 31 Issue 4, p923-935, 13p

مصطلحات موضوعية: X-rays, ELECTRON density, TOMOGRAPHY, X-ray imaging, HOLOGRAPHY, GRAPHICAL projection, ELECTRON holography

مستخلص: X‐rays can penetrate deeply into biological cells and thus allow for examination of their internal structures with high spatial resolution. In this study, X‐ray phase‐contrast imaging and tomography is combined with an X‐ray‐compatible optical stretcher and microfluidic sample delivery. Using this setup, individual cells can be kept in suspension while they are examined with the X‐ray beam at a synchrotron. From the recorded holograms, 2D phase shift images that are proportional to the projected local electron density of the investigated cell can be calculated. From the tomographic reconstruction of multiple such projections the 3D electron density can be obtained. The cells can thus be studied in a hydrated or even living state, thus avoiding artifacts from freezing, drying or embedding, and can in principle also be subjected to different sample environments or mechanical strains. This combination of techniques is applied to living as well as fixed and stained NIH3T3 mouse fibroblasts and the effect of the beam energy on the phase shifts is investigated. Furthermore, a 3D algebraic reconstruction scheme and a dedicated mathematical description is used to follow the motion of the trapped cells in the optical stretcher for multiple rotations. [ABSTRACT FROM AUTHOR]

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المؤلفون: Seo, Jinsol, Lee, Hyungwoo, Eom, Kitae, Byun, Jinho, Min, Taewon, Lee, Jaekwang, Lee, Kyoungjun, Eom, Chang-Beom, Oh, Sang Ho

المصدر: Nature Communications; 6/20/2024, Vol. 15 Issue 1, p1-11, 11p

مصطلحات موضوعية: TWO-dimensional electron gas, ELECTRON gas, ELECTRON energy loss spectroscopy, ELECTRIC distortion, ELECTRON holography, GAS dynamics

مستخلص: Since the discovery of two-dimensional electron gas at the LaAlO3/SrTiO3 interface, its intriguing physical properties have garnered significant interests for device applications. Yet, understanding its response to electrical stimuli remains incomplete. Our in-situ transmission electron microscopy analysis of a LaAlO3/SrTiO3 two-dimensional electron gas device under electrical bias reveals key insights. Inline electron holography visualized the field-induced modulation of two-dimensional electron gas at the interface, while electron energy loss spectroscopy showed negligible electromigration of oxygen vacancies. Instead, atom-resolved imaging indicated that electric fields trigger polar distortion in the LaAlO3 layer, affecting two-dimensional electron gas modulation. This study refutes the previously hypothesized role of oxygen vacancies, underscoring the lattice flexibility of LaAlO3 and its varied polar distortions under electric fields as central to two-dimensional electron gas dynamics. These findings open pathways for advanced oxide nanoelectronics, exploiting the interplay of polar and nonpolar distortions in LaAlO3. Understanding two-dimensional electron gas at the LaAlO3/SrTiO3 interface to electrical stimuli remains incomplete. Here, the authors reveal that the lattice flexibility of LaAlO3 and its varied polar distortions under electric fields as central to 2DEG dynamics. [ABSTRACT FROM AUTHOR]

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المؤلفون: Carlino, Elvio, Taurino, Antonietta, Hasa, Dritan, Bučar, Dejan-Krešimir, Polentarutti, Maurizio, Chinchilla, Lidia E., Calvino Gamez, Josè J.

المصدر: Nanomaterials (2079-4991); May2024, Vol. 14 Issue 10, p872, 14p

مصطلحات موضوعية: ELECTRON beams, NANOCRYSTALS, ELECTRON holography, MATERIALS science, SOFT X rays, RADIATION damage

مستخلص: Seeing the atomic configuration of single organic nanoparticles at a sub-Å spatial resolution by transmission electron microscopy has been so far prevented by the high sensitivity of soft matter to radiation damage. This difficulty is related to the need to irradiate the particle with a total dose of a few electrons/Ų, not compatible with the electron beam density necessary to search the low-contrast nanoparticle, to control its drift, finely adjust the electron-optical conditions and particle orientation, and finally acquire an effective atomic-resolution image. On the other hand, the capability to study individual pristine nanoparticles, such as proteins, active pharmaceutical ingredients, and polymers, with peculiar sensitivity to the variation in the local structure, defects, and strain, would provide advancements in many fields, including materials science, medicine, biology, and pharmacology. Here, we report the direct sub-ångström-resolution imaging at room temperature of pristine unstained crystalline polymer-based nanoparticles. This result is obtained by combining low-dose in-line electron holography and phase-contrast imaging on state-of-the-art equipment, providing an effective tool for the quantitative sub-ångström imaging of soft matter. [ABSTRACT FROM AUTHOR]

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المؤلفون: Berberova-Buhova, Nataliya, Nedelchev, Lian, Mateev, Georgi, Nikolova, Ludmila, Stoykova, Elena, Ivanov, Branimir, Strijkova, Velichka, Hong, Keehoon, Nazarova, Dimana

المصدر: Photonics; May2024, Vol. 11 Issue 5, p425, 12p

مصطلحات موضوعية: DIFFRACTION gratings, POLYMER films, THIN films, ELECTRONIC records, SURFACE properties, ELECTRON holography, FERROELECTRIC polymers, HOLOGRAPHY

مستخلص: In this work, we study the polarization properties of diffraction gratings recorded in thin films of the azopolymer PAZO (poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzene sulfonamido]-1,2-ethanediyl, sodium salt]) using digital polarization holography. Using two quarter-wave plates, the phase retardation of each pixel of the SLM is converted into the azimuth rotation of linearly polarized light. When recording from the azopolymer side of the sample, significant surface relief amplitude is observed with atomic force microscopy. In contrast, recording from the substrate side of the sample allows the reduction of the surface relief modulation and the obtaining of polarization gratings with characteristics close to an ideal grating, recorded with two orthogonal circular polarizations. This can be achieved even with a four-pixel period of grating, as demonstrated by our results. [ABSTRACT FROM AUTHOR]

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المؤلفون: Wang, Yun-Yu, Sankaranarayanan, Sandeep, Kaushik, Naveen, Wang, Zhouguang, Smith, Mike, Jin, Qiang, Rossi, Tommaso

المصدر: Microscopy Today; May2024, Vol. 32 Issue 3, p16-21, 6p

مصطلحات موضوعية: ELECTRON holography, ELECTRON traps, METAL oxide semiconductors, FOCUSED ion beams

مستخلص: It has been hypothesized that trap charge plays an important role in PMOS (positive-channel metal oxide semiconductor) device reliability. By using electron holography, trap charge in a spacer oxide was observed to cause an inversion of junction in an un-stressed PMOS device prepared using a Ga+ focused ion beam (FIB). Through 400°C annealing for 10 min in vacuum, trap charge in the spacer oxide dispersed and the junction recovered. Technology computer-aided design (TCAD) simulation was used to confirm the positive trap charge effect on the junction. Furthermore, the simulation showed that a low concentration of positive trap charge at the Si/SiO2 interface under the spacer led to a higher tunneling current due to an abrupt junction near the Si surface through a very localized junction inversion. [ABSTRACT FROM AUTHOR]

: Copyright of Microscopy Today is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Radziszewska, Agnieszka, Czyż, Olaf

المصدر: Materials (1996-1944); May2024, Vol. 17 Issue 9, p2060, 16p

مصطلحات موضوعية: COPPER, ELECTRON holography, CRYSTALLIZATION, AMORPHOUS alloys, COPPER alloys, PULSED lasers

مستخلص: Amorphous Fe77Cu1Si13B9 ribbons were treated with pulsed laser interference heating (PLIH). The research results will significantly contribute to a better understanding of the impact of PLIH on crystallisation and magnetic properties in precisely defined micro-areas of Fe77Cu1Si13B9 (FeCuSiB) ribbons, which has not yet been described in the literature. It was confirmed here that the use of the laser heating process allowed for the achievement of two-dimensional crystallised micro-areas, periodically distributed (at a distance of 17 µm) on the surface of the amorphous ribbons. The correlation between structural changes (SEM, TEM, HRTEM) and the distribution of magnetic field lines of heated amorphous Fe77Cu1Si13B9 ribbons is presented. Particular attention is paid to structural changes in micro-areas where, by controlling the laser interference heating process, the partial crystallisation of amorphous alloys and the formation of clusters or single nanocrystallites (α-Fe(Si)) embedded in an amorphous matrix occur. The addition of copper to the FeSiB alloy promoted the inhibition of grain growth. Electron holography of micro-areas confirmed shifts in the magnetic field lines in the areas of nanocrystallites, the presence of which in the structure caused the magnetisation of the surrounding amorphous matrix. [ABSTRACT FROM AUTHOR]

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المؤلفون: Sujin Lee, Yoshihiro Midoh, Yuto Tomita, Takehiro Tamaoka, Mitsunari Auchi, Taisuke Sasaki, Yasukazu Murakami

المصدر: Applied Microscopy, Vol 54, Iss 1, Pp 1-10 (2024)

مصطلحات موضوعية: Noise reduction, Wavelet hidden Markov model, Electron holography, Nd-Fe-B magnet, Microscopy, QH201-278.5

الوصف: Abstract In this study, we investigate the effectiveness of noise reduction in electron holography, based on the wavelet hidden Markov model (WHMM), which allows the reasonable separation of weak signals from noise. Electron holography observations from a Nd2Fe14B thin foil showed that the noise reduction method suppressed artificial phase discontinuities generated by phase retrieval. From the peak signal-to-noise ratio, it was seen that the impact of denoising was significant for observations with a narrow spacing of interference fringes, which is a key parameter for the spatial resolution of electron holography. These results provide essential information for improving the precision of electron holography studies.

وصف الملف: electronic resource

Relation: https://doaj.org/toc/2287-4445

URL الوصول: https://doaj.org/article/e1f7b9818b5842818b356cae9904f473

المؤلفون: Becker, Maximilian R., Loche, Philip, Netz, Roland R.

المصدر: Journal of Chemical Physics; 12/28/2022, Vol. 157 Issue 24, p1-12, 12p

مصطلحات موضوعية: SURFACE potential, ELECTRON holography, LIQUID-vapor interfaces, MOLECULAR magnetic moments, ELECTRIC fields, PHOTOELECTRON spectroscopy, MOMENTS method (Statistics)

مستخلص: Although conceptually simple, the air–water interface displays rich behavior and is subject to intense experimental and theoretical investigations. Different definitions of the electrostatic surface potential as well as different calculation methods, each relevant for distinct experimental scenarios, lead to widely varying potential magnitudes and sometimes even different signs. Based on quantum-chemical density-functional-theory molecular dynamics (DFT-MD) simulations, different surface potentials are evaluated and compared to force-field (FF) MD simulations. As well explained in the literature, the laterally averaged electrostatic surface potential, accessible to electron holography, is dominated by the trace of the water molecular quadrupole moment, and using DFT-MD amounts to +4.35 V inside the water phase, very different from results obtained with FF water models which yield negative values of the order of −0.4 to −0.6 V. Thus, when predicting potentials within water molecules, as relevant for photoelectron spectroscopy and non-linear interface-specific spectroscopy, DFT simulations should be used. The electrochemical surface potential, relevant for ion transfer reactions and ion surface adsorption, is much smaller, less than 200 mV in magnitude, and depends specifically on the ion radius. Charge transfer between interfacial water molecules leads to a sizable surface potential as well. However, when probing electrokinetics by explicitly applying a lateral electric field in DFT-MD simulations, the electrokinetic ζ-potential turns out to be negligible, in agreement with predictions using continuous hydrodynamic models. Thus, interfacial polarization charges from intermolecular charge transfer do not lead to significant electrokinetic mobility at the pristine vapor–liquid water interface, even assuming these transfer charges are mobile in an external electric field. [ABSTRACT FROM AUTHOR]

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المؤلفون: Lee, Sujin, Midoh, Yoshihiro, Tomita, Yuto, Tamaoka, Takehiro, Auchi, Mitsunari, Sasaki, Taisuke, Murakami, Yasukazu

المصدر: Applied Microscopy; 4/17/2024, Vol. 54 Issue 1, p1-10, 10p

مصطلحات موضوعية: ELECTRON holography, MARKOV processes, SIGNAL-to-noise ratio, SIGNAL separation, SPATIAL resolution, NOISE control

مستخلص: In this study, we investigate the effectiveness of noise reduction in electron holography, based on the wavelet hidden Markov model (WHMM), which allows the reasonable separation of weak signals from noise. Electron holography observations from a Nd2Fe14B thin foil showed that the noise reduction method suppressed artificial phase discontinuities generated by phase retrieval. From the peak signal-to-noise ratio, it was seen that the impact of denoising was significant for observations with a narrow spacing of interference fringes, which is a key parameter for the spatial resolution of electron holography. These results provide essential information for improving the precision of electron holography studies. [ABSTRACT FROM AUTHOR]

: Copyright of Applied Microscopy is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)