Abstract With the increasing diversity of SEM detectors today, classification based solely on secondary and backscattered electrons is no longer sufficient; there is a growing need to specify energy and emission direction when discussing image information. In particular, for detectors capable of energy discrimination, an appropriate method for classifying images is required. We propose a nomenclature for classifying images by explicitly indicating energy, emission direction, and detector position following the abbreviations “SE” and “BE.” Energy is displayed as three bands - A, B, and C- defined by the ends of the spectrum on a logarithmic axis, while emission direction is divided into regions 1, 2, and 3 in 30° increments from the zenith angle. Detectors are designated with “o” or “d” depending on whether they are circularly symmetric or directional with respect to the primary electron beam. For example, they are denoted as SE/A2o or BE/AB3d. Using this notation, we classify images obtained with low-pass secondary electron detectors (Fountain detector) and high-pass backscattered electron detectors, and discuss their characteristics.
Abstract Purpose We investigated whether ligament-derived collagen fibrils traversing the cartilage/fibrocartilage region toward the tibial bone could be visualized using SEM. Methods ACL specimens were obtained from four patients with ACL rupture (aged 16–49 years) and three older adults (aged 60–75 years) with osteoarthritis. Specimens were fixed and examined under light microscopy (LM; sections stained with light green and aldehyde fuchsin), transmission electron microscopy (TEM; modified tannic acid method), and scanning electron microscopy (SEM; NaOH-treated blocks). Results The central portion of the ACL consisted of parallel-arranged collagen fibers, with thread-like elastic fibers stained by aldehyde fuchsin sparsely distributed among them. SEM following NaOH treatment revealed collagen fibrils (diameter ∼120–140 nm). Elastic fibers were also scattered among collagen bundles on SEM. On TEM, electron-dense structures consistent with elastic fibers (diameter ∼600 nm) were identified. At the tibial insertion, LM demonstrated that the ACL branched within the cartilage and attached to the tibia. SEM enabled discrimination between the bundled ACL collagen fibrils and the finer collagen fibrils (diameter ∼80 nm) surrounding chondrocytes. Conclusion We histologically demonstrated that branches of the human ACL pass through the joint and attach to the tibia. Ligament-derived collagen fibrils were observed branching and descending through the cartilage/fibrocartilage region toward the tibial bone.
Abstract Iterative multislice electron ptychography enables depth sectioning but its range is constrained by the real-space patch imposed by detector sampling. Reconstruction using converted 4D-STEM patterns into electron-event lists decouples the model’s reciprocal-space sampling interval from detector pixels size, reducing data volume, and enabling event-based loss function evaluation. The effect of patch size to the computable depth range, and the validity of the proposed method were demonstrated by simulation. The experimental demonstration on SSZ-13 zeolite shows improved reconstruction quality with preserved depth profiles; under 4× detector binning, reconstruction quality and depth sectioning are retained by selecting a finer reciprocal-space sampling interval, thereby extending the computable depth range without sacrificing angular coverage.
In this study, we investigate the feasibility of evaluating the chemical bonding states using an electron-beam-based spectroscopic method implemented on a conventional scanning electron microscope and energy dispersive X-ray spectroscopy (SEM-EDS) system. The widely used surface-sensitive techniques such as X-ray absorption spectroscopy (XAS) often require synchrotron facilities and are not suitable for localized measurements. The critical excitation energies of silicon and silicon oxide featuring distinct absorption edge energies in XAS were determined by measuring the onset of characteristic X-ray emission as a function of incident electron energy. The observed difference in the critical excitation energy is consistent with the reported chemical shifts in the Si 1s binding energies and Si-K absorption edge energies. Systematic evaluations confirmed that variations in the beam current, instrumental instability, and surface charge-up did not significantly affect the measured thresholds. These results indicate that the proposed method captures chemically sensitive information related to the core-level electronic structure. The proposed approach provides a simple and accessible alternative to probe chemical bonding states and offers potential advantages for localized analysis because of the small probe size achievable with electron beams.
We theoretically investigated how the arrangements of tilt points affect the suppression of diffraction contrast in tilt-scan-averaged differential phase contrast scanning transmission electron microscopy (tDPC STEM). To examine the effectiveness of tilt-point arrangement, we compared three sampling patterns: conventional 4-fold, 6-fold symmetric concentric patterns and the Vogel spiral pattern based on Fermat's spiral with the golden angle. Multislice simulations were performed for GaN, GaAs, Si, and SrTiO3 crystals. Although all patterns approached similar converged values with sufficiently high tilt numbers, their convergence behaviors differed markedly. The concentric patterns exhibited non-monotonic decay and showed discrete fluctuations in residual diffraction contrast, whereas the Vogel spiral showed a smoother and more monotonic decrease over a wide range of tilt numbers. This behavior was consistently observed across the crystals with different crystal symmetries. These results show that rotationally asymmetric and uniformly distributed tilt sampling is advantageous for the robust diffraction-contrast suppression in DPC STEM, and identify the Vogel spiral as an effective tilt pattern for this purpose.
