Analysis of time-of-flight secondary ion mass spectrometry (TOF-SIMS) data is crucial for interpreting extremely intricate TOF-SIMS data of complex samples such as biological tissues and intelligent devices. Combination of imaging analysis and spectrum analysis is powerful to extract unknown important components and to identify specific materials. In this article, principles of three important data analysis techniques for TOF-SIMS data, principal component analysis (PCA), multivariate curve resolution (MCR) and G-SIMS, are briefly introduced. And, examples of their applications to TOF-SIMS data are also shown and discussed.

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  Distribution of lithium ions in crystals is an important issue for development of advanced lithium ion batteries. Using spherical aberration-corrected electron microscope, lithium columns in crystals have been visualized with heavy element ones by a new method of scanning transmission electron microscopy (STEM) called as annular bright field (ABF) imaging. ABF images are taken by setting an annular detector in bright field disk. It is so powerful that it visualizes not only lithium but also hydrogen columns in battery and storage materials. Some suggested explanations of ABF imaging mechanism, hollow-cone beam illumination method, phase object approximation and s-state channeling model, will be reviewed.

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  In order to develop a gas-sheet target, the angular distribution of molecular flux at the exit of narrow tubes and slits was simulated by employing the Monte Carlo method.
  In the case of the longer tubes, the greater part of the flux is collimated near the polar angle. However, when the ratio of length to diameter, L/d (L: length, d: diameter), is greater than 10, angular distribution is almost independent of the L/d value. Even at the L/d value of 100, the fraction of outgoing molecules with polar angles less than 0.01 rad is less 0.5%.
  The molecules emitted from the slit can be shaped into a sheet. To do so, the following two conditions need to be satisfied: L≫b and a≫b. The letters a, b, and L represent the lengths of the long and short sides, and the depth of the slit, respectively. With the parameter set of L:a:b=100:50:0.1, the fraction of outgoing molecules collimated within the azimuth of 0.01 rad becomes 25% of all molecules.

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  The usual way for reduce outgassing of a large structure in vacuum is to bake the whole vacuum chamber containing the structure. However, this method needs a huge heater capacity and there are limits caused by the heat expansion of the chamber. The solution is to raise the temperature of the structure inside without heating the vacuum chamber. This is achieved by installing a heat source inside the chamber and by inserting the heat shield between the structure and the chamber walls to direct the heat to the structure. In the particle accelerator field, it is often required to reduce outgassing of structures inside vacuum chambers. One example is a kicker magnet, which is installed in a vacuum chamber and consists mainly of ferrite and aluminum alloy. As known from former experience the main outgassing component from ferrite is water. We applied the above mentioned method to the outgassing reduction of such a kicker. We are able to direct most of the heat flow toward the kicker magnet by inserting the heat shielding plates and thus outgassing was successfully reduced.

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  For reliable and stable operation of a particle accelerator, it is necessary to shield the accelerated particles inside the vacuum chambers from unwanted external stray magnetic fields. Instead of an external shield, it can be quite efficient to design a vacuum chamber itself as a magnetic shield. Therefore, we have developed a vacuum chamber with magnetic shielding properties by using the magnetic material SUS430. For this chamber not only magnetic shielding is required, but also a low outgassing rate, so that it can be used for a high intensity particle accelerator. First, we measured the outgassing rate of SUS430 using small samples with the differential pressure flow method. The results suggested that SUS430 is compatible with our low outgassing rate requirement. Then a vacuum chamber designed for installation into the synchrotron was manufactured using SUS430, and it was confirmed that the outgassing rate of the chamber is low enough.

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  SiC/SiC composites are promising materials for the plasma-facing walls in a fusion reactor. In order to investigate the effect of helium ion irradiation on the deuterium retention behavior of SiC/SiC composites, helium ion irradiation followed by deuterium ion irradiation was performed on SiC/SiC composites using an ECR ion source. After the irradiation experiments, deuterium retention behavior was measured using thermal desorption spectroscopy technique. The total amount of retained deuterium was enhanced with helium pre-irradiation. Thermal desorption spectra of D₂ showed two main peaks which could be explained as deuterium released from its Si-D and C-D bonds, respectively. These two peaks temperatures were shifted to low temperatures with helium pre-irradiation. The atomic composition of silicon at the sample surface increased after helium irradiation. Due to this silicon composition increase, the amount of deuterium trapped due to the Si-D bond increased greatly. This data indicates a large effect of helium irradiation on the deuterium retention behavior of SiC/SiC composites.

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  Surface-channeling at grazing incidence of 550 keV protons on electron-bombarded KCl(001) and KBr(001) surfaces is investigated. In order to derive step density of the surfaces as a proportional function of electron-fluence lying in a range below 3×10¹⁵ cm⁻², intensity distributions (scattering patterns) of reflected protons on a fluorescent screen are observed. With increasing the fluence, the scattering patterns shift to lower scattering angle. The peak-angles of the luminous intensity are compared with calculated results of computer simulations. For both KCl and KBr surfaces, the electron fluence of 1.0×10¹⁵ cm⁻² is equivalent to the density of monolayer steps of 1.3×10⁵ cm⁻¹ piled upon in the simulation.

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  Quadrupole mass spectrometry (QMS) has been applied to monitor the etching processes in a localized plasma etching system. An inward plasma was employed for etching in which the etching gas was discharged in the narrow gap between the etched sample and the entrance of an evacuating capillary tube. As the etching products are immediately evacuated through the capillary, a QMS system equipped at the capillary exit is able to analyze the products without any loss in concentration via diffusion into the chamber. Two kinds of samples, thermally grown SiO₂ on Si and spin-coated polyimide film on Si, were etched, and the chemical species in the evacuated etching gas were analyzed with QMS, which enables monitoring of the composition of the surface being etched. Samples of thermal SiO₂ were etched with CF₄ plasma. The peak height of the SiF₃⁺ signal during the SiO₂ etching was lower than that observed during etching of the silicon substrate, leading to endpoint detection. The endpoint detection of the polyimide film etching was conducted using two etching gases: pure O₂ and pure CF₄. When O₂ was used, the endpoint was detected by the decrease of the mass peak attributed to CO. When CF₄ was employed, the plasma was able to etch both the polyimide film and Si substrate. Then the endpoint was detected by the increase of the mass peak of SiF₃⁺ produced by the etching of the Si substrate.

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  Temperature measurement of Si surfaces being etched by an inward plasma technique was performed with a sampling period of 0.1 s. A band edge thermometer was employed, which is based on the temperature dependence of the absorption edge of silicon. The temperature rise associated with the inward plasma etching was demonstrated to be smaller than that with an outward technique. Time dependence of the temperature and optical emission intensities from the plasma were measured simultaneously. As plasma was ignited and the discharge glowed, the temperature rose abruptly in the time domain within 3 s, after which it approached a linear dependence. The transition in temperature change from an initial abrupt one to a linear manner coincided with the maxima of the optical emission intensity of F atoms as well as total emission intensity integrated between 200 and 1000 nm. The magnitude of the initial temperature change linearly correlated with the intensity of the optical emission line by F atoms, i.e., the number of F radicals, while its correlation with the total intensity was obscured. It was therefore concluded that light absorption is not sufficient to explain the initial temperature change. Other effects including heat conduction of the etching gas to the surface and reaction heat associated with etching should be included.

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  The electron beam ion source (Kobe EBIS) has been developed to perform modification of surfaces using highly charged ions (HCIs). Recent study revealed that periodic intermission of electron beam improves charge state distribution of extracted ions. The repetition of ON/OFF of electron beam with the period in the order of 100ms and the width of beam-off time being 1ms or less made it possible to produce Ar¹⁵⁺ to Ar¹⁷⁺ effectively, while the charge is limited less than 14+ under the ordinary operation mode. A spike of HCIs is also produced at each moment of electron beam off.

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  Large variation in basic memory properties is a serious issue that hinders the practical use of ReRAMs. This study revealed that one of the main factors causing variation is the presence of multiple filaments in each memory cell. An operating filament switches to another filament having the smallest set voltage (V_set) at each instance of switching. We propose a resistive switching model that takes the presence of multiple filaments into consideration. A Monte Carlo simulation based on the resistive switching model reproduces the V_set distribution. The dependence of 〈V_set〉 on the number of switching cycles was predicted by the model and confirmed experimentally.

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  We have investigated surface roughnesses and magnetic properties of Co ferromagnetic thin films evaporated on polyethylene naphtalate (PEN) organic substrates. As a result, the surface roughness decreases from 1.3 to 0.55 nm with increasing the Co thickness up to 55 nm, where a two-step smoothing phenomenon can be seen. As for magnetic properties, the coercive force and the squareness of the hysteresis loop show the maximum values at a Co thickness of 5.3 nm. This experimental result can be explained by the competition between the shape magnetic anisotropy and the induced magnetic anisotropy of Co ferromagnetic thin films.

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  The effects of N₂ [mass number: 28] and O₂ [mass number: 32] gas impurities on ZnS host material and the emission center in the active layers of a thin-film electroluminescent device were examined for the impurity gas concentration. Electron spin resonance (ESR) experiments were performed to examine the Mn²⁺ cohesive state. As the partial pressure of N₂ increased, the L₃₀ and the maximum luminance efficiency decreased, the threshold electric field strength increased due to the reduction in the concentration of the isolated single Mn²⁺. When the partial pressure of N₂ was increased, the isolated single Mn²⁺ and the clustered Mn²⁺ concentration decreased and the interaction between the isolated single Mn²⁺ and the clustered Mn²⁺ increased. When O₂ gas impurity is introduced to the sputtering environment, some Zn atoms combine with O causing a deficiency of S.

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  We focused on the basic adsorption properties of two types of cations, viz., 1-methoxymethyl-1-methylpyrrolidinium (MMMP) and 1-ethyl-3-methylimldazolium (EMI), on graphene, as a first step in investigating the properties of carbon electrodes in an electric double layer capacitor. To clarify the basic adsorption properties, we used first principles calculation based on the density functional theory with the generalized gradient approximation for the exchange-correlation energy. We investigated the electrical dipole moment formed between the cations and graphene and found that electric dipole moment per cation formed by MMMP is larger than by EMI. In addition, we found that intramolecular bindings of MMMP are stronger than those of EMI. Based on these results, we conclude that MMMP is more suitable as the material for electric double layer capacitor than EMI.

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