Black-phosphorus (BP) like Bi(110) structure attracts attentions because it has been predicted to be a 2D topological insulator theoretically if its surface buckling is small enough. Although BP-like Bi(110) islands are widely known to nucleate on various substrates in the initial stage of epitaxial growth, it has not been elucidated how the islands grow in detail. We report the result of our detailed STM measurement of the growth of BP-like Bi(110) islands on Si(111)7×7 substrate. BP-like Bi(110) islands which consist of the stacking of paired bilayers have even number layers height exclusively. However it was found that not only even number but also odd number layers high Bi(110) islands nucleated. The coverage of Bi islands with odd number layers heights increased and got close to that of even number layers high Bi(110) islands. The Bi(110) islands with odd number layers heights were considered to have not the BP-like but the sandwich structure.

In the present study, we investigate how the structure of the SiC (0001) surface changes due to the adsorption of metal atoms (Ni, Pt, Pd, Cu), and the stable adsorption site of metal atoms on the (0001) surface. When the first-principles band calculation is performed for the three types of slab models (type-I, type-II, and type-III), it is estimated that type-I is the most energetically stable. Further, it is clear that Pt forms the most stable adsorption on the surface of SiC (0001) among the four kinds of metal atoms.

Defects in graphene play an important role in various fields. Therefore, it is necessary to understand the relationship between local defects in graphene and their electronic structures. We used scanning tunneling microscopy to observe a single-layer small graphene sheet, which was cleaved from a graphite surface. It turns out that there exist several patterns of atomic-scale bright spots, that are probably induced by local defects. In particular, we will focus on a rectangular-like lattice, and discuss its origin.

Terminal modification can effectively functionalize graphene nanoribbons (GNRs). For conventional methods, stable molecules such as phthalocyanines were used as terminal molecules to be fused with synthesized GNRs. However, a different synthetic method using different molecules is required to explorer new functions of GNRs. In this study, we synthesized GNRs with new terminal structures by co-adsorbing two kinds of precursors during on-surface synthesis. As a terminal, we used a molecule that has a naphthyl group. We revealed that the naphthyl-derivated terminal of the modified GNRs works as a molecular switch.

One-dimensional silicon nanoribbons (SiNRs) have the potential applying to future electronics devices because its compatibility with current silicon-based electronics devices and the theoretical outstanding electronic properties such as size-dependent band gap. Here, with the deposition of Si on Ag(111) surface, we have grown SiNRs. We investigate SiNRs on Ag(111) with a combination of scanning tunneling microscopy(STM), atomic force microscopy(AFM) and density functional theory (DFT) calculations. We obtained the atomic resolution STM and AFM images, which reveal that SiNRs have the same width and align along the equivalent orientations of Ag(111). The main body of SiNRs was found symmetric about the long axes of ribbons, but the terminals of SiNRs break the symmetry. The observations indicate that SiNRs are stable under room temperature. In order to determine the detailed atomic structure of SiNRs, based on the STM and AFM observations, we performed the DFT calculations. The calculation results reveal the buckled single-layer structure of SiNRs, which agrees well with the experimental results.

The detailed adsorption structures of hexa-tert-butyl-haxabenzocoronene (HB-HBC) on the Si(111)-√3×√3-Ag surface and molecule-substrate interactions are investigated by low-temperature scanning tunneling microscopy (STM). The author find that the center of the HB-HBC molecule absorbed on the surface appear bright or dark, in which the dark appearance is preferred. Furthermore, these appearances are inverted during the STM scan, each inversion rate of which is systematically derived from STM images. From the temperature dependence of the inversion rage, the activation energies for the bright to dark and the dark to bright are extracted.

We have observed the moire pattern of the hexagonal iron nitride layer on the Cu(111) substrate by using scanning tunnel microscopy. By observing the tiny change in the moire pattern, we have visualized the local strain of the iron nitride layer. This tiny shift of the iron nitride lattice is too small to be measured by using conventional STM observation. Our observation for the moire pattern enables us to measure the small strain.

In the conventional ceramics manufacturing process, firing process is essential, and this process consumes a lot of energy and emits carbon dioxide. However, in our laboratory, we have developed a technology to solidify ceramics without firing process. This solidification mechanism was investigated by electron paramagnetic resonance.

In recent years, miniaturization and integration have been progressing in semiconductor development.For further development, it is necessary to control the cleaning of the side surface and facet surface of 3D Si and the formation of functional nano-thin films. The purpose of this study was to control the formation of nano-thin films on the pyramid facet surfaces. We worked on the fabrication of 3D Si{111} pyramids, the cleaning of facet surfaces, and the structural analysis of Fe silicide nano thin films. These structural evaluations were achieved using SEM and LEED observations.

In 1/6 and 1/3 ML-Pb/Si(111), it is known that both structure have √3×√3 periodicity by LEED measurement. The structure model of 1/6 and 1/3 ML-Pb/Si(111) is proposed by STM measurement and theoretical calculation, however, there structure are not exactly determined. In this study, we performed structural analysis of Pb/Si(111)-√3×√3 surface superstructure by using total-reflection high-energy positron diffraction (TRHEPD) with data-driven science. In the presentation, we will show analysis results and the structure models which are best agreement with the experiment. We will also discuss a validity of the structure model, comparing with previous study.

This is a feasibility study of determining hydrogen positions on metal surfaces by RHEED. We take c(2x2)-H on Pd(100) as an example. By using calculated results of RHEED intensities taking scattering from hydrogen explicitly into account, we will show it possible to determine hydrogen position of c(2x2)-H on Pd(100). A discrimination function which is similar to the reliability factor in LEED by Pendry is used to determine the most likely position of hydrogen. It is necessary to choose appropriate diffraction conditions where the fractional order beam intensities change as a function of hydrogen position.

An asymmetric Ti₂O₃-added row structure model was proposed for the TiO₂(110)-(1×2) reconstructed surface as a result of total-reflection high-energy positron diffraction (TRHEPD). Density functional calculation (DFT) was carried out for each symmetric and asymmetric Ti₂O₃-added row structure models to understand the stability and the stabilization mechanism of the asymmetric Ti₂O₃-added row surface. The density of states of asymmetric Ti₂O₃-added row structure models showed mid-gap state isolated from conduction band contrary to the symmetric model, which states exist at the bottom of conduction bands.

We report on the "atomic-resolution holography microscope" that combines a compact DELMA, a two-dimensional analyzer with high energy-resolution, and a small electron beam column (MINI-EOC from APCO) with a scanning electron microscope function. A nano region can be confirmed with a scanning electron microscope, and the three-dimensional atomic arrangement around the isolated atom in the nano region can be directly analyzed by holography. High energy-resolution allows valence-separated holographic analysis.

SIMS is a powerfull technique for surface analisys. Current Status and Future Prospect of SIMS will be disscussed from Novel Ion beamOrganic Materials to Latest Mass Analysis Technique Biological Materials.

Transmission electron microscopes are powerful instruments that allow observations of materials with high spatial resolution. Since the images are formed using the transmitted electrons, basically two-dimensional projection information of the object is obtained. In this talk, recent improvements to achieve quantitative three-dimensional observations of materials and new attempts for further developments are introduced.

In order to clarify the hydrogen embrittlement of steel materials, which causes cracks and fractures in the materials, time-course hydrogen distribution images of steel samples obtained by electron transition induced desorption (ESD) and the images reflecting crystal structures obtained by scanning electron microscopy (SEM) and backscattered electron diffraction (EBSD) were integrated, and then analyzed as multimodal data to investigate the relationship between hydrogen permeation and crystal structures.

Matrix effects which make the intensity of secondary ion dramatically change depending on co-existing materials could be a big problem for quantitative analysis and interface evaluation. We have developed a new method for the interface evaluation using information entropy of secondary ions.

Multivariate analysis techniques such as PCA, which have been applied to complex TOF-SIMS data, are based on liner models and therefore they are not appropriate for managing non-linear phenomena such as matrix effects. One of the unsupervised artificial neural network methods, autoencoder, was applied to the TOF-SIMS data of polymers.

It is important to clarify the contribution of the Auger electrons for the energy distribution of the secondary electron in order to interpret its fine structure of the spectrum of the secondary electron with less than 20eV. We analyze the differential spectra of the logarithm of the N(E) spectrum at the different acceleration voltages, in which are chosen the higher and lower than the ionization potential of the Auger electron. For Al, the contribution of Auger electron is almost absent and is attributed to the cascade by the electron after the plasmon decay. In addition to the M23VV Auger electrons and the electron by the plasmon decay, the structure from the other excitation is also observed for Ti. It may be due to the cascade by the electrons excited in the unoccupied state.

This presentation provides the quantum deep field (QDF), which provides the electron density with an unsupervised but end-to-end physics-informed modeling by learning the atomization energy on a large-scale dataset. QDF performed well at atomization energy prediction, generated valid electron density, and demonstrated extrapolation.

The spectral data analysis such as peak fitting requires the time-consuming procedure to estimate the parameters of the fitting model. This procedure is a major bottleneck in the research cycle. In this presentation, I will report an efficient peak-fitting method based on the EM algorithm to solve the bottleneck and an improvement of the method by extending available fitting models based on the ECM algorithm.

We are developing methods for exploring magnet compounds using machine learning techniques and first-principles calculation. In this presentation, we discuss a framework of optimization we have recently proposed based on a machine learning technique called Bayesian optimization. We will show that our framework can efficiently optimize magnetization, Curie temperature, and formation energy-which are key performance indicators of magnet compounds-with respect to the choice of additive elements and their amount.

Understanding the function of real materials in heterogeneous system, such as magnetic domain and metallographic structure, has been a outstanding issue in materials science. Thus the development of a consistent and fast analysis method that consider the defects, roughness, crystal sizes, etc. is utmost important. Here we are developing a machine learning-based formula that can treats the microscopic morphology and describes the macroscopic properties based on the energy of the system. One interesting application is to describe the coercivity based on the structure and micromagnetic properties. The Landau free energy theory is very hard to be implemented in complex applications due to the pinning de-pinning process of the domain walls. Thus, the development of pseudo free energy that considers the metallography structure is necessary to describe the physics in inhomogeneous polycrystalline systems.

There are a lot of electron-beam based techniques in surface analysis, and each of them has its own characteristics, but they also have, at least, one characteristics in common, the information about the target sample is obtained through the analysis of identified signal data. These techniques generally are inefficient for quantitative purpose because only the signal data contribute to the conclusions, while other detected data, the overwhelming majority of measured data, have been completely disregarded as undesirable background data. Therefore, there is a need for a universal method that could extract meaningful information from background data. In this talk, we proposed a data-driven analysis method to extract meaningful information from the background signal and to propose an important breakthrough for the next generation surface analysis. The unique feature of this method is to use the combinations of a large number of spectral groups measured by intentionally changing a plurality of experimental conditions, to describe the background data, instead of interpreting individual spectrum in terms of physically meaningful parameters.

Machine learning (ML) can accelerate the analysis of measured data and materials development. In this talk, We will introduce recent ML applications for powder X-ray diffraction patterns and X-ray absorption spectra.

In synchrotron radiation experiments, a large amount of complex high-dimensional data can be obtained. The cuurrent issue is to analyze large amounts of data at high speed. We attempted to make a machine learning model on-site using the measured data, analyze it, and determine the next measurement condition based on the result. In the presentation, we will introduce specific research results and discuss their possibilities, including issues of on-site machine learning.

A pulsed discharge plasma in water and in contact with water have been attracting much attention as a promising technology in various fields such as agriculture and environmental remediation. The pulsed power technology enables the instantaneous production of non-thermal plasma which produces various chemical species, such as hydroxyl radicals and ozone. These species play an important role in sterilization effect and the decomposition of organic compounds in wastewater. In this paper, characteristics of plasma discharge inside bubble generated using a pulsed power generator and chemical are described. The decomposition of persistent organic compounds such as 1,4-dioxane, formic acid and dichloromethane by the plasma discharge are demonstrated for environmental application. A nutrient solution treatment system using plasma is developed for practical use in hydroponics for agricultural application. Its performance of enhancement of plant growth rate and inactivation of bacteria in nutrient solution are demonstrated.

PEDOT, which is widely used as a conductive polymer, is generally produced by oxidative polymerization of monomer (EDOT) over several hours. We investigated the possibility of EDOT polymerization using atmospheric pressure plasma as a simple and quick production method. In this work, measured infrared spectra of the EDOT before/after the plasma treatments. We discuss possibility of formation of PEDOT by our method through comparison to the IR spectrum of PEDOT given in a literature.

Plasma chemical vapor deposition (PECVD) of amorpous carbon films has a lot of parameters. One of them is a source supply position. The source supply position is changed: one is from the plasma source, and the other is from the underside of the substrate. Deiffereces of chemical states of the depsoted films are measured with infrared spectroscopy. We found that the films is deposited without a source molecular structure when the source is supplied from plasma source.

GaN film growth characteristics have been investigated by using newly developed high-density convergent plasma sputtering device with the liquid Gallium target and the nitrogen plasma irradiation. We especially focus on the nitrogen gas flow ratio in Ar-N₂ mixed gas to investigate GaN film growth characteristics. The X-ray diffraction measurement was used to evaluate crystal orientation of deposited films. In this presentation, we will present the influence of the nitrogen gas flow ratio on GaN film growth using high-density convergent plasma sputtering device at room temperature.

In order to apply energy to ionized sputtered particles, we tried plasma potential control using an apparatus consisting of dual cathodes to which bipolar voltage can be applied. Shifting the pulse discharge timing half a cycle and applying the positive voltage during pulse OFF periods, a plasma potential higher than the ground potential can be maintained throughout the period. In this study, the plasma potential rise by positive voltage application was investigated using the Langmuir probe measurement. It was confirmed that the plasma potential rose by applying more than +30 V during the pulse OFF period. It was also confirmed that the pulse-OFF-period target functioned as an anode by applying the positive voltage.

Based on plasma quantities of the Mg-CF₄ DC discharge, which is assumed to be a typical electronegative discharge, measured by a single Langmuir probe method as a function of CF₄ / (Ar + CF₄) discharge gas ratio, the discharge structure of electronegative Dc magnetron sputtering discharge with negative plasma potential, such as cathode sheath potential differnce, anode sheath difference, will be discussed. In addition, reasons of asymmetry of probe current-voltage characteristic which is in contradiction with the change in negative ion/electron ratio in the probe current will be discussed.

Titanium thin films were prepared by rf magnetron sputtering to observe the difference in crystal orientation among the samples deposited at the different positions. Deposition was performed on silicon substrates of which surface had been oxidized, and characterization was performed by rocking curve measurement in x-ray diffraction. The films deposited under the condition: substrate temperature of 300 degrees in Celsius, argon pressure of 2.0 Pa, and rf power of 50 W showed no significant difference. This result does not agree with the fact that the tungsten films deposited at the outer position showed different orientation.

We have successfully fabricated TiN films with isolated-nanocolumnar structures via reactive sputtering with glancing-angle deposition scheme. The nanostructured TiN films have strong (100) orientation. Due to light scattering, the reflectance of the TiN films are suppressed in the visible range.

We focused on Shirasu, a volcanic ejecta peculiar to Southern Kyushu, as a new anti-fog material. The purpose of this study is to develop an anti-fog material that can maintain the anti-fog effect for a long period of time. In this study, in order to realize a thin film structure in which moisture adsorption and desorption occur repeatedly due to changes in ambient humidity over a long period of time, we attempted to fabricate a porous thin film using the phase separation phenomenon of glass. Specifically, we have established a technology for producing a phase-dividing mother glass target in which the produced thin film exhibits a phase-dividing phenomenon, and a film-forming technology capable of exhibiting a phase-dividing phenomenon and making it porous in a series of phase-dividing treatment processes. Then, the physical properties of the obtained thin film were evaluated, focusing on the antifogging property.

A typical EC material, WO₃ was deposited at a high pressure of 3 Pa to form a sparse film structure in which Li cations were easily injected. In a previous study, 500 nm film thickness samples showed a stable decolorization, however, 1000 nm film thickness films did not completely decolorize, suggesting the retention of cations injected into the deep trap. In the present study, to suppress the injection of cations into the 1000 nm thick film, the applied voltage at the time of cations injection was varied, and the transmission spectrum and the amount of transferred charge at the time of coloring and decoloring were compared.

We present a study on the adsorption of corrosion inhibitors, anti-wear additives and friction modifiers from a synthetic and a mineral base oil on metal (Fe2O3) surfaces. In order to obtain quantitative and spatial data during the adsorption process we set up a combined quartz crystal microbalance (QCM-D) and confocal scanning laser microscope (CLSM). In addition to QCM-D and CLSM, also a UHV-tribometer was used to study the performance of gas phase deposited additives films without environmental interferences. In combination with macroscopic performance tests using a “ball-on-three-plates-tribometer” and corrosion tests, the adsorption, the morphology and the mechanical properties of the additives were correlated with their performance.

Friction is one of the most familiar physical phenomena to us. The behavior of friction has been studied since ancient times. Recently new experimental techniques, such as vacuum technology, friction force microscopy (FFM), and surface force measurement devices, enable us the stydy of atomic scale friction and have been ushering in a new era in friction research. Some researchers have been trying to explain macro-scale friction from such microscopic phenomena. The largest scale frictional phenomenon on Earth is earthquakes. However, the research on the connection between micro- and macro-friction has not been sufficiently successful yet. In this talk, I would like to introduce the physics behind friction phenomena from the nanoscale to the macroscale, as well as various applications.

Superlubricity, where the friction vanishes or significantly small, is of great interest in friction and it has been realized at the nanoscale in the piconewtons, but not yet at the macroscale. We demonstrate the macroscopic superlubricity is realized using a superlubric pillar array. The superlubricity of piconewtons appearing at a single silicon nanopillar is a novel type, which is quite different from the structural superlubricity studied so far and enables the macroscopic superlubricity. The conditions at which the macroscopic superlubricity appears are summarized using the friction coefficient and the viscous friction coefficient. This work clarifies the factor that controls fiction at the macroscopic scale.

Molecular mechanisms of lubrication have been studied by high resolution atomic force microscopy (AFM). We will report on two different material system, which exhibit fascinating lubrication properties at the nanometer scale. Graphene is the two-dimensional building block of graphite, a well-known solid lubricant. We will report how friction and the molecular structure of a liquid lubricant oil change at the steel interface due to the presence of graphene. Ionic liquids are promising materials for lubrication, given their viscosity, low vapor pressure, and electric conductivity. When confined to the nanometer-scale gaps, the structure of ionic liquids becomes ordered in molecular layers. Normal forces oscillate when closing the gap between the confining surfaces. We introduce magnetically actuated dynamic shear force microscopy as a method to measure the shear viscosity of confined ionic liquids.

The Stribeck curve is a fundamental concept to characterize the shear behavior in the entire range of lubrication, including hydrodynamic, mixed, and boundary lubrication regime. This concept covers both rheological and tribological aspects, and is widely used to grasp the shear behavior of many practical systems. However, the Stribeck curve has at least two quantitative problems: (i) baseless assumption that the effect of increasing sliding velocity on lubricant film thickness (and resulting friction force) is quantitatively equivalent to that of decreasing load; and (ii) the viscosity of lubricant is regarded as constant, which is incorrect. The surface forces apparatus (SFA) is very suitable to approach this issue; the SFA enables the direct measurement of film thickness using optical technique simultaneously with friction measurements, and boundary lubrication is quantitatively described using effective viscosity. According to this approach, bulk rheological properties and thin film tribological properties have been quantitatively connected, which leads to the updated Stribeck curve for smooth surfaces.

Superconductivity has been observed in crystalline monolayers, such as Pb and In, formed on Si(111). Generally, the two-dimensional superconducting state is fragile and susceptible to structural defects. For example, surface steps repel the vortices in some cases and but in other cases they work as a pinning site for the vortices, depending on the superconducting phases. It is, however, unknown what is the critical parameter deciding the behavior of the vortices against the steps. Here by scanning tunneling microscopy we investigated a few monolayers of Pb deposited on Si(100) substrates, and examined whether superconductivity is formed there and if formed how the vortices behaves under magnetic field. Since Pb/Si(100) surface phases are very sensitive to the Pb coverage, we introduced an automatic evaporation and annealing system to control the coverage precisely. Details will be discussed in the presentation.

The metal-free phthalocyanine (H₂Pc) has excellent properties for the thermal and chemical stability that are applied to organic electronic devices such as gas sensor and organic thin-film solar cells. The structure of the H₂Pc films affect the property of these devices. The H₂Pc molecules are adsorbed on silicon carbide (SiC) reconstructed surface at room temperature under ultrahigh-vacuum (UHV) condition. The surface structure and electronic structure were studied by Low Energy Electron Diffraction (LEED) and Metastable-atom Induced Electron Spectroscopy (MIES), respectively. As a result, the H₂Pc molecular orientation depended on the deposition rate of H₂Pc. We will discuss about electronic structure at H₂Pc adsorbed (3×3) reconstructed surface with annealing.

Silicon carbide (SiC) is a wide band gap semiconductor because it has excellent properties for electric device such as high breakdown voltage and high thermal conductivity. SiC crystal form some reconstructed surfaces such as (3×3) and (6√3×6√3)R30^o. Ionic Liquids (ILs) are salt in liquid phase in room temperature. ILs have attracted much attention for their excellent physical properties such as very low vapor pressure, high thermal stability and chemical stability. Detailed knowledge of electronic structure of ILs is necessary for electrochemical applications. In this study, we measured the surface electron structure at the [EMIm]Tf₂N deposited SiC reconstructed surface (6√3×6√3)R30^o using metastable atom induced electron spectroscopy (MIES) and low-energy electron diffraction (LEED). We will discuss about the behavior of ionic liquid molecule with the deposition rate of ionic liquid.

Hybrid of a conductive metal and a flexible resin has been demanded for the purpose of thinning and lightening of semiconductor devices in recent years. A self-assembled film may be used to modify or functionalize a metal surface and a resin surface. However, each material requires different molecules. 6-triethoxysilylpropylamino-1,3,5-triazine-2,4-ditiol (TES) has both a thiol group capable of binding to metal and a functional group capable of binding to resin (three ethoxy groups binding to Si). Therefore, it is possible to form a self-assembled film on each surface with only TES molecules, and it can be expected that the process efficiency of surface modification is improved. We examined the surface modification with TES and the formation process of self-assembled thin film on copper surface by X-ray photoelectron spectroscopy.

While the nanoimprint technology is widely used as a microfabrication technique, it has become difficult to predict empirically the nanotribological phenomena in the interface between mold and organic materials during the processes such as alignment, filling and releasing at sub-10 nm scale. In this study, as a starting point for solving the problems caused by nano-tribological phenomena, we analyzed the atomic stress distribution of each individual atom to discuss the cause of the shear stresses at the atomic level.

Spin crossover (SCO) complexes are materials whose magnetic properties can be controlled by external stimuli, such as heat, pressure, light and so on. Among the SCO complexes, some of them show different physical properties between crystals and films. For example, a SCO complex (Fe(tdap)₂(NCS)₂) shows a sharp SCO transition at around 350 K in solid phase, while it shows a slow transition with a hysteresis in thin film phase. By performing infrared spectroscopy, we clearly observed peaks indicating the vibrations of the thiocyanate ligand together with a peak suggesting the presence of high-spin states in the solid phase. In this presentation, we will discuss the origin of the difference in magnetic property of this Fe(tdap)₂(NCS)₂ based on vibration measurements.

Preparation of an organic thin flim pattern by vacuum deposition with a shadow mask has been generally used.We found that when mask-deposition of low-Tg photochromic diarylethenes (DAEs), the molecules diffused to the masked surface region.We confirmed this phenomenon using selective Mg-vapor deposition of DAE.This phenomenon may also occur in other low-Tg organic semiconductor materials.

Ultrafast relaxation dynamics of photoinjected holes in the valence band of silicon has been studied using time- and angle-resolved two-photon photoelectron differential spectroscopy. We found that the photoexcitation with fs laser pulses causes a transient reduction in intensity of direct bulk transition peak, together with a peak broadening and a low-energy peak shift. The observed peak broadening and energy shift recovered completely in several ps, while the intensity shows a partial recovery in the same time range followed by a slow relaxation lasting a few hundreds of ps. Also. the temporal evolution of the difference photoemission image reveals that the photoinjected holes initially form a non-equilibrated distribution and then establish a quasi-thermalized distribution during the rapid relaxation process. We will discuss the many-body effects in the valence band states in photoexcited silicon, which rule the ultrafast relaxation process.

RhPd bimetallic alloys are regarded as promissing substances for high catalytic activity in CO oxidation reaction, nevertheless the adsorption behavior on the surface are still missing. In this work, we investigated the CO adsorption on RhPd(100) single-crystal from UHV to elevated pressure up to 1 Torr, using polarlization modulation infrared reflection absorption spectroscopy (PM-IRAS) and ambient pressure X-ray photoelectron spectroscopy (AP-XPS).