Graphene is a perfect impermeable membrane for gases but permeable to hydrogen ions. Hydrogen ion permeation shows the isotope effect, i.e., deuteron is slower than proton when permeating graphene. However, the permeation mechanism and the origin of the isotope effect are still unclear. Here, we propose a strategy to discuss the hydrogen ion permeation mechanism of graphene by developing an ion source with ultraslow, monochromatic, and mass-selected hydrogen ion beam. We employed a hemispherical monochromator and a Wien filter for the ion source to achieve the energy and mass resolutions of 0.39 eV and 1 atomic mass unit, respectively. The energetically sharp ion beam is expected to allow us to directly measure the permeability of graphene with high accuracy.

This paper investigates the influence of oxide-trapped charge distributions on the C-V dependence of lateral source—base and drain—base junctions of nanoscale metal-oxide-semiconductor field-effect transistors (MOSFET) through simulation. Distributions suitable for different types of electrical voltages are considered. Simulation results show that the transition capacitance of lateral junctions at low applied voltages depends on the position of the maximum of the distributions along the channel. The ratio of the transition capacitances of source—base and drain—base junctions at low applied voltages depends on the position of the distribution maximum. This dependence can be used to estimate the distribution of oxide trapping charges injected into the oxide layer under different electrical stresses.

The deformation of the patterns of metal catalysts used in the chemical vapor deposition (CVD) of graphene is difficult to predict. This makes it difficult to control the shape of the graphene sheet produced. To obtain insights into the deformation of metal catalysts employed in CVD, changes in their morphology and crystal structures were investigated in detail using scanning electron microscopy (SEM) and electron backscatter diffraction before and after CVD. The fabricated graphene was identified using Raman spectroscopy. The Cu patterns of the >600-nm-thick films, formed on synthetic quartz glass, remained almost unchanged after the CVD process performed at 1000°C, whereas that of the 300-nm-thick film was deformed. The morphological changes in the patterns of the thin Cu film indicated that partial dewetting of Cu occurred on the glass surface during the CVD process. After conducting the CVD process, the Cu patterns showed asperities which correspond to grain boundaries, and their surfaces were mostly composed of (111) phases. The Raman spectroscopy and SEM results showed that the graphene sheets selectively formed on the Cu patterned surface and comprised a patchwork of single-layer and multilayer domains.

The creation of three-dimensional (3D) geometrical shapes with atomically ordered surfaces and the investigation of their physical properties are major steps contributing to the development of a new paradigm in surface science. We produced a 3D-patterned Si sample with atomically flat and reconstructed {111} facet surfaces, and investigated its structural and physical properties. To apply the conventional techniques in surface science to 3D samples with various oriented surfaces, instead of two-dimensional planar samples, an appropriate relationship between the crystallographic surface ordering on the 3D-architected surfaces and the angle-resolved photoelectron spectroscopy (ARPES) setup considering the configuration in 3D space is indispensable. The distinctive and complex low-energy electron diffraction (LEED) patterns reflecting the 3D-arranged facet surfaces showed the realization of atomically reconstructed facet surfaces on 3D-patterned Si. Surface states of the 3D-patterned Si{111} surfaces are mapped by ARPES by considering the 3D geometrical relationship. The selection of the appropriate alignment of the incident electron beam (light) for the target surfaces allows the clear observation of the band dispersion from the produced {111}7×7 facet surfaces in 3D space. Our demonstration of accessibility of ARPES technique could provide useful guidelines for new methodologies, giving a fundamental understanding of 3D-shape-induced novel functionalities.

Control of magnetism has been an attracting issue due to its scientific interests and technological application. In such research, theoretical simulation plays an important role. We performed a Landau-Lifshitz-Gilbert simulation on the recovery process of a ferromagnet from a magnetization reversed state in a square lattice system. During the process, there can be a situation that the magnetization reversal state is enhanced or completed transiently, which may be observed experimentally.

Soft X-ray absorption and emission spectra near the K-edges of B and N in ammonia borane (NH₃BH₃) powder are measured. These spectra show a solid crystalline spectral shape rather than a molecular spectrum. The calculation result of partial density of states by a cluster model is in good agreement with the measured spectral shape. In addition, for the purpose of investigating the reaction mechanism of ammonia borane, atomic hydrogen is irradiated, and in-situ observation is performed by soft X-ray spectroscopy. It is observed that π* absorption splits into six peaks in the B-K absorption spectrum under atomic hydrogen irradiation. Of these, the four peaks on the high-energy side are identified as hexagonal boron nitride (h-BN) and its O-substituted chemical species.

Cu plating is extensively used as a surface treatment material for metals. However, the formation of dendritic Cu crystals has not been confirmed when a difficult-to-plate material such as a Zn-Al substrate is coated. Generally, the crystals formed on the Zn-Al substrate are characterized by the complex structure that develops an ultrathin sheet with a large surface area owing to its dendritic structure. The larger surface area increases heat dissipation and the sheet becomes a heat sink. Cu dendrite crystals have potential for industrial applications. In this study, we formed characteristic spheres (crystal balls) from Cu dendrite crystals and the formation process was shown.

The hydrogen isotope (H and D) concentrations in the two types of Li_1+xAl_xTi_1−x/2Ge_1−x/2P_3−yO₁₂ and Li_1+x+yAl_xTi_2−xSi_yP_3−yO₁₂ (LATP: AG-01 and SP-01, respectively) electrolytes, soaked in D₂O for 19—22 days and subsequently exposed to air at room temperature and humidity of 80% for 11—21 days, were measured by combining elastic recoil detection with Rutherford backscattering spectrometry. The total numbers of H and D atoms in AG-01 and SP-01 were estimated to be approximately 5.0 and 0.66 atoms, respectively, after the absorption of H₂O and D₂O and the replacement of H by D. Field emission scanning electron microscopy and atomic force microscopy images revealed that many black substance formations with dimensions of approximately 0.5 × 3.0 μm² in area and less than approximately 200 nm in thickness appeared on the surface of the D₂O-soaked and air-exposed AG-01. These formations appeared because of the segregation of Li from the bulk to the surface by the reactions of H₂O and D₂O with the doped Ge, which might lead to H and D trapping at the Li substitutional sites.

We study the polarization dependence of the structure factor in multi-atom resonant X-ray Raman (MARX-Raman) scattering. The calculations for the GaN (C_3v) and SnO₂ (C_2v) show some preferable structures to enhance the MARX-Raman signal intensity through the structure factor which depends on the relative arrangement of the incident X-ray polarization and the surrounding local atomic geometry. The theoretical calculations help us to derive new information from the MARX-Raman.

Surface micro- and nanobubbles were formed in situ using a conventional scanning electron microscope by radiolysis of water confined in liquid cells with electron-transparent windows. The shapes and contact angles of the bubbles formed at the window corner were directly measured using a scanning electron microscope. All the observed contact angles were close to 90°, regardless of the size, indicating that the corner bubbles had shapes that almost maximized the Laplace pressure. Bubble formation far from the electron irradiation site was also analyzed using a Monte Carlo simulation.

Photoelectron momentum maps (PMMs) have the potential to reveal various physical properties of organic molecules adsorbed on the substrate. It has been reported that the multiple scattering theory may be required for precise analysis of the PMMs. However, simulation of the PMMs including the multiple scattering is computationally demanding, which makes the detailed analysis difficult. Here, we propose simple and efficient methods to evaluate the multiple scattering processes, by reducing the number of matrix multiplications. We applied the methods to a copper phthalocyanine molecule and show that the simulated PMMs converges in a few scattering processes with greatly reduced computational time as compared with the standard multiplication method.

Metal-free phthalocyanine (H₂Pc) has unique features, such as visible light absorption and excellent thermal and chemical stabilities, which render them applicable to organic electronic devices. However, the condition of the phthalocyanine (Pc) film affects the performance of these devices. Therefore, it is necessary to establish a control method for Pc adsorption and the thin-film growth. In the present study, we observed the electronic structures and morphology of H₂Pc structures adsorbed on reconstructed SiC surfaces using metastable atom induced electron spectroscopy, low-energy electron diffraction, and atomic force microscopy. The H₂Pc molecules were deposited on each SiC reconstructed surface (particularly graphene) until the H₂Pc thin film was formed. The molecular orientation of H₂Pc adsorbed on the graphene surface changed from a tilted structure to a flat-lying structure with the increase in the deposition time. As the amount of deposition increases, the H₂Pc molecules formed a thin film on the surface during the island growth. We further discuss the adsorption structure and the thin-film growth of the H₂Pc molecules with the increasing deposition time on the SiC reconstructed surface.

Calcium carbonate nanoparticles are often surface-treated with organic compounds such as fatty acids. The activated calcium carbonates not only exhibit excellent application properties, but also can be applied as eco-friendly inorganic-organic hybrid materials. However, the microscopic adsorption structure of organic compounds on calcite surfaces is not yet well understood. In this study, we performed computational simulations based on density functional theory to investigate adsorption states of stearic acid (SA) on a calcite (104) surface. Based on the first-principles ionic relaxation and molecular dynamics simulations for several types of SA−SA and calcite−SA bonding models, a SA bilayer model on the calcite (104) surface is predicted to be a possible stable structure. The proposed structure model is well consistent with the experimentally predicted adsorption mechanism of SA on the calcite (104) surface.