This report describes the usage, specification, troubles and the countermeasures of dry pumps in Japan Proton Accelerator Research Complex (J-PARC). In J-PARC, while dry scroll pumps (DSP) are widely used, many of them are being replaced with roots pumps due to frequent maintenance and troubles of DSP. Some of the facilities use roots pumps with special specifications, such as radiation resistant specifications, separate power supply, and with diaphragm type, etc. Although some problems have occurred with both DSPs and roots pumps, they have been addressed by revising maintenance methods and improving parts, contributing to stable operation for users.

X-ray Photoelectron Spectroscopy (XPS) is widely used as one of the primary techniques for investigating the surface chemical composition of materials. In recent years, there has been a significant increase in the demand to observe the electronic states associated with chemical reactions under operating conditions close to real environments, such as in fuel cells and catalytic materials. To address this need, Near Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) instruments have been developed and continuously improved. This article introduces atmospheric pressure photoelectron spectroscopy at pressures of several bars and provides data examples. Additionally, we present software technology designed to visualize spatiotemporal-resolved data expected to be obtained in the future using this measurement technique.

We overview plasma-enhanced chemical vaper deposition (PECVD) of high-quality thin-film silicon. In PECVD, such a film is grown by the deposition of precursors, which is generated by the gas-phase reactions of source gases in plasma. The growth of the film depends on the surface reactions of precursors and the reactions in the growing film, i.e., in-film reactions, which influences the film structure and properties. The in-film reactions also take place after the growth, i.e., post-growth annealing. So, the reactions should be properly controlled throughout the growth and annealing for the high-quality film formation. Here, the growth kinetics and related reactions are presented for device-grade hydrogenated amorphous silicon (a-Si:H) films.

In the vacuum freeze drying process, four technologies are important : freezing, drying, antioxidant treatment and packaging, the first two of which constitute its core technologies. Freezing concerns its rate and temperature, while drying necessitates attention to cold trap temperature and vacuum degree.

Non-equilibrium processes such as nucleation are difficult to observe in situ using transmission electron microscopy (TEM) because of spatiotemporal stochastic process. Therefore, we have been developing a method to predict/detect nucleation events and observe under low electron doses conditions in real time with the support of machine learning. Low electron dose observation is important to avoid radiolysis of water in the observation of aqueous solutions using liquid-cell TEM. Our data-driven TEM that can suggest observation points to the operator by processing in situ observation data in real time. In other words, it is data-driven TEM in which the TEM helps the operator, rather than the TEM being driven by the data. By incorporating the two codes into the TEM's software, nucleation can now be observed efficiently.

Nanobubbles (NBs), with their unique physicochemical properties and promising applications, have become an important research topic. Generation of monodispersed bulk NBs with specified gas content remains a challenge. We developed a simple method for generating bulk NBs, using porous alumina films with ordered straight nano-scaled holes. Nanoparticle tracking analysis (NTA) is used to confirm NB formation. The NTA data demonstrates that NB size is distributed discretely with a uniform increment factor of √2. To explain the observed characteristic size distribution of NBs, we propose a simple model in which two NBs of the same size are assumed to preferentially coalesce.

Dynamic behavior of electrochemical interfacial phenomena is key issue for material science. Scanning probe microscope can observe the surface on the nanoscale, however, it is difficult to discuss the reaction process due to poor temporal resolution. High-speed atomic force microscopy (HS-AFM) is one of powerful in-situ observation tools. Here, we would like to introduce the HS-AFM applications for electrochemistry, such as Cu electrodeposition, polyethylene glycol (PEG) adsorption, and nanobubble electrolytic evolution by HS-AFM.

Microscopic studies on electrolyte solution/electrode interfaces provide the most fundamental information not only for understanding the electric double layer formed at the interfaces but also for designing sophisticated electrochemical devices. As with various electronic devices, it is critical to understand the electronic structure of the interfaces, but direct assessment has been limited by the presence of solution. This article presents our exploration of the electronic structure of electrochemical interfaces using photoelectron spectroscopy and electrochemical measurements.

In this article, we provide an overview of our recent study on light-induced electron emission from single fullerene molecules and subnanometric optical control of their electron emission sites. After depositing molecules on a sharp metallic needle and applying strong electric fields at the apex of the needle, single-molecule protrusions appear on the apex. The electric fields are further enhanced at the protrusions and the enhanced fields drive electron emissions from the single molecules. Single-molecule electron sources can thereby be created. By irradiating such electron sources with light, we observed large modulations in the electron emission patterns. Our simulations revealed that the emission patterns represent molecular orbitals in a single molecule, a mystery scientists have been trying to get to the bottom of for the past 70 years. Our simulations also explain that light-induced modulation is driven by changes in the molecular orbitals that the emitted electrons pass through. In effect, we realize that there are subnanometric modulations in electron emission sites.

Single-molecule junctions (SMJs) have attracted wide attention due to their unique electronic property originating from their structure, i.e. single molecule connected to the electrodes at both ends. Although the junction structure has significant effects on the electronic property of the SMJs, the experimental method to define the geometry of the bridged molecule is limited. Recently, we have succeeded in the observation of surface-enhanced Raman scattering (SERS) spectroscopy in combination with the current-voltage (I–V) response measurement, revealing the junction structure of SMJs. The I–V response obtained by the combination measurement provides the electronic structure of the molecule fluctuated by the connection to the metal electrodes, allowing the analysis of the effect of the charge transfer on the SERS spectra. The strong electronic coupling between metal and molecule enhances the charge transfer resonance and it triggered the excitation of the “Raman silent mode” in the bulk state. Therefore, we have detected the unique SERS spectra in SMJs and revealed the contribution of the charge transfer effects on the SERS spectra at the single-molecule level.

The studies about surface chemistry of formic acid on Cu-based model catalysts including our recent investigation are reviewed from the surface-science point of view. The Cu-based model catalysts including steps and Zn-deposition have been prepared using the well-defined single crystalline Cu surfaces. Formate species are formed by the decomposition from formic acid on the model catalysts surfaces. Various surface spectroscopies have been applied for the assignments of intermediate species, the quantitative estimation of their coverages and the kinetics of adsorbed species. The active sites and reaction mechanisms of the decomposition of formic acid and the hydrogenation of formate species are discussed.

Tribology is an interdisciplinary field related to the science and technology of friction, wear, and lubrication, and is expected to contribute to the realization of a carbon-neutral society. Recent advances in tribology are largely due to dramatic advances in nanotechnology and surface science. Recent topics are introduced along with the history of tribology.

Faceted macrostep formed at equilibrium is demonstrated based on numerical calculations using the tensor network method and the Monte Carlo method. The adopted model is a lattice model where the surface roughness excitations and the step-step attractive energy (ε_int) are taken into consideration. We calculated ε_int–T and p–T faceting diagrams for faceted macrosteps where T is the temperature, and p is the surface slope for an inclined surface. Applying the faceting diagrams to Si(113)＋(114) surfaces, the step-step attractive energy is approximately 123 meV. We also discuss elementary step attachment/detachment processes to/from the faceted macrostep near equilibrium.

In this article, we discuss applications of topology to materials science. We explain how topology is used to express the structure and shape of materials. The structure of a multicyclic polymer is described by applying graph theory and the 3-dimensional shape is described by applying knot theory. Polycontinuous patterns of microphase separation of a block copolymer melt can be analyzed by applying the 3-dimensional topology. We also discuss the topological structures of interlocking molecules composed of metal-peptide rings using the concept of polyhedral links.

Organometal halide perovskites have captured wide interest as a promising material for light-weight and high-efficiency solar cells. Through recent studies of the organometal halide perovskite solar cells (PSCs), the composition of organometal halide perovskites is recognized as one of the key factors in the improvement of the PCE. In this study, we investigated mixed cation perovskite absorber. Additionally, we successfully constructed monolithic PSC mini-module without I-V hysteresis. In the case of MA-free PSCs, the 24.9% PCE (0.187 cm²) and 21.6% PCE (2.76 cm² monolithic PSC mini-module) were obtained, respectively. We also developed semitransparent perovskite top cells with higher durability and transmittance for tandem solar cells. The PCEs of 19.5% (certified 19.3%) and 26.2% were achieved for a 1 cm² semi-transparent perovskite top cell and four-terminal PSC/CIGS tandem solar cells, respectively.

It has been reported that the introduction of ferromagnetism by various ways into topological insulators (TIs) can induce concerted effects, resulting in various novel magnetic phenomena such as quantum anomalous Hall effect and skyrmions. In addition, recently, efforts to increase the observation temperature of quantum phenomena by enhancing the crystal quality and improving electronic coherence have been pursued with great enthusiasm. Self-assembled regular alloy crystals such as Mn(Bi,Sb)₂Se(Te)₄ are called “intrinsic” ferromagnetic TIs that have recently attracted much attention, and we have observed skyrmions in sandwich structures based on these crystals. Furthermore, we have newly observed the ferromagnetic proximity effect even at room temperature at the heterojunction interface between Fe and topological crystalline insulator SnTe by polarized neutron reflectometry. As an extension of these efforts, it is hoped that the unique properties of TIs will be utilized to develop next-generation robust devices for such as spintronics and quantum computing.

A new 3 GeV light source named “NanoTerasu” is under construction at Aobayama new campus of Tohoku university. NanoTerasu will form a photon science platform together with SPring-8, which covers a wide spectral range from UV to hard X-rays, by delivering brighter and more coherent soft to tender X-rays with superior stability and reliability. Installation of the accelerator system is in progress for the first light in 2023. NanoTerasu employs a four-bend achromat lattice using combined-function bending magnets to achieve a low emittance of about 1 nmrad with a small circumference of 349 m and a beam current of 400 mA. The storage ring consists of 16 cells to provide 28 user beamlines. This paper presents an overview of NanoTerasu and describe details of the storage ring vacuum system.

We introduce the results of in situ observation of the surface and the solid-liquid interface of calcium carbonate in atomic-level by frequency modulation atomic force microscopy (FM-AFM) in the presence of additives. We have found that the calcite surface transformed into the aragonite structure by the cooperative effect of magnesium and a hydrophilic polypeptide. Furthermore, high-resolution imaging of solid-liquid interface revealed that these additives did not adsorb on the calcite surface but significantly changed the hydration structure in the vicinity of the surface. Especially magnesium ions contribute to change the hydration structure due to their hydrophilicity.

Room-temperature wafer bonding can realize new electronic devices, power devices, optical devices, and microelectromechanical systems. Atomic diffusion bonding (ADB) of wafers is a promising process to achieve room-temperature wafer bonding : thin metal films are fabricated on two flat wafer surfaces using sputter deposition, followed by bonding of the two films on the wafers in vacuum. Any mirror-polished wafer including glass can be bonded using ADB. Recently we demonstrated ADB of wafers at room temperature using oxide films and nitride films. Incident light can pass through transparent wafers bonded with oxide films without reduction in intensity. Moreover, the electrical conductivity of the bonded oxide films and nitride films is negligible. These properties are useful to produce new optical or electrical devices. This paper assesses the technical potential and current status of ADB.

Under the competition of ferromagnetic interaction and Dzyaloshinskii-Moriya interaction, magnetic vortices in real-space, skyrmions, can be induced on a topological insulator (TI), which reflects the chiral spin structure on the gapped Dirac cone in the momentum space. Here, we observe skyrmions emerge on surfaces of two self-assembled ferromagnetic TI layers, Mn(Bi_1－xSb_x)₂Te₄, separated by a spacer of non-magnetic TI layer, (Bi_1－xSb_x)₂Te₃, through topological Hall effect (THE) by tuning the Fermi level with optimizing the Bi/Sb ratio. By the spacer-thickness-dependence of the magnitude of THE, we find that the moderate coupling of surface states between the top and bottom Mn(Bi_1－xSb_x)₂Te₄ layers is essentially important for inducing and stabilizing skyrmions. Moreover, the highly-ordered Mn atoms in the Mn(Bi_1－xSb_x)₂Te₄ lead to a strong exchange interaction therein, making skyrmions “soft magnetic”. This would open an avenue toward a topologically robust easy-rewritable novel magnetic memory for spintronics.