Film deposition process during helium-added acetylene plasma is investigated with multiple-internal-reflection infrared absorption spectroscopy (MIR-IRAS). The sp²-C, the sp-C, the sp³-CH, -CH₂, and the sp-CH components are formed in the deposited film. We found that the films are deposited through the addition reaction during the plasma. We also suggest that the amounts of the sp³-CH, -CH₂ components are etched during He-added acetylene plasma.

Plasmas or discharge are often generated using noble gases and applied to various fields such as surface treatments of materials and biological fields. The behavior of electrons and ions (swarm parameters) help to understand the plasmas and discharges. Swarm parameters are often acquired at low pressure. Recently, plasmas generated at atmospheric pressure have applied in many fields. To acquire the swarm parameters at atmospheric pressure, this paper proposes new measurement method for electron drift velocity and effective ionization rate coefficient. First, these parameters are acquired in nitrogen gas at atmospheric pressure. Second, they are acquired in mixed gas (synthetic air was mixed with argon gas). These results are compared with the results of BOLSIG＋ simulation. We conclude that the new measurement method is useful in gases without negative ions ; even in gases with negative ions of oxygen, this method are valid at reduced electric field E/N ≦ 31.6×10^－21 Vm².

Layered oxyfluoride single-crystalline thin films of Sr₂RuO₃F₂, Ca₂RuO_2.5F₂, and Sr₂IrO_2.5F₃ were fabricated via topochemical fluorination. All the fluorinated films exhibited an insulating behavior and a largely expanded c-axis than the precursors. Sr₂RuO₃F₂ film was a Mott insulator with Ru^4＋ states and had two inequivalent F^－ sites in the SrO layers. In contrast, Ca₂RuO_2.5F₂ film had the Ru^3＋ state and only one F^－ site in the CaO rock-salt blocks. This discrepancy is probably due to the larger lattice distortion in the Ca₂RuO₄ precursor. The conduction mechanism of Ca₂RuO_2.5F₂ film was described by two-dimensional variable range hopping. The effective total angular momentum J_eff＝3/2 of Sr₂IrO_2.5F₃ film was stabilized upon fluorination owing to the large electronegativity of fluorine. The conduction mechanism of Sr₂IrO_2.5F₃ film was described by Efros-Shklovskii variable-range hopping. These results will be useful for modifying electronic states by anion doping to explore unprecedented electronic properties in layered oxides.

We study the atomic and electronic structures of the monolayer Kondo lattice CePt₂/Pt(111) using scanning tunneling microscopy/spectroscopy (STM/STS). A monolayer (2×2)-CePt₂ is formed by depositing Ce atoms on Pt(111) and annealing at 720 K. Atomically resolved STM images reveal that the monolayer (2×2)-CePt₂ is protected by a chemically inert topmost Pt₄ layer. The quasiparticle interference (QPI) measured on the (2×2) structure indicates a Shockley-type surface state similar to that on Pt(111) with a downward shift due to charge transfer from the underneath CePt₂ layer. We discuss a possible two-dimensional coherent Kondo effect (heavy fermion) with the observed STS spectra.

The superconducting properties of atomic layers are strongly affected by the presence of surfaces and interfaces. In this study, we aim to elucidate the mechanism by which the superconducting transition temperature T_c is modulated by the adsorption of organic molecules. We have performed a comprehensive study on the atomic layer superconductor Si(111)-(√7×√3)-In with adsorption of ZnPc molecules using electron transport measurements, angle-resolved photoemission spectroscopy, and ab initio calculations. Through comparison with previous studies, the results show that the observed T_c increase cannot be attributed to the charge transfer from molecules as previously thought. We propose a new mechanism based on the push-back effect caused by molecule adsorption.

The electrode potential dependence of the behavior of ionic liquid molecules (BMI-TFSA) at the Au electrode interface with dimpled surface structure in ionic liquids was investigated using AC electrochemical impedance and electrochemical ATR-IR methods. Comparing the positive and negative going scans, large hysteresis was observed in the electric double-layer capacitance and the behavior of TFSA^－ molecules. Although similar hysteresis was observed at the flat gold electrode, it was largely enhanced at the dimpled electrode. From these results, it is inferred that a large potential barrier is formed in the dimples, which inhibits the desorption of TFSA^－.

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.

The formation of functional metal oxide crystals is widely required in CMOS backend processes. Recently, digitally processed DC sputtering (DPDS) was developed as an alternative layer-by-layer process to pulsed-laser deposition (PLD) for device development. DPDS enables the alternating process of depositing ultra-thin layers of metals and oxidizing them by using pulses of reactive gases that are partially synchronized with the sputtering of specific metals. However, it was found that crystallites were formed inhomogeneously due to damage by oxygen radicals, and there was room for improvement in crystallinity. Therefore, pulsed non-radical oxidation (NRO) was introduced into DPDS to avoid radical damage. We therefore designed a DPDS sequence using dual-cathode sputtering and gas pulses synchronized with sputtering interruptions. The sufficient oxidation for the metal few layers using NRO was confirmed. We also demonstrated the space group control of monoclinic (Er_0.1Y_0.9)₂SiO₅ and the reduction of oxygen vacancies, due to DPDS-NRO.

In this paper, I propose a new model named virtual solid cell (VSC) to treat porous media more simply in the Direct Simulation Monte Carlo method. The conventional random solid cell (RSC) model represents porous media by randomly arranging solid cells in a fluid domain. In contrast, the VSC model basically treats porous media as a fluid domain, but it produces the same effect as the RSC model by imposing a stochastic limit corresponding to the porosity on the inter-cell transfer of molecules. Due to its advantage as a stochastic method, the VSC model enables one-dimensional simulation of rarefied gas flow passing through porous media, contributing to a significant reduction in computation time. It also facilitates the treatment of complex porous media with various porosities. Furthermore, the VSC model shows its potential as a new boundary model to describe surface roughness and conditions.