Based on our previous finding that room temperature ionic liquids (RTILs) can be used as electrolyte solutions without any solvent for in situ observation of electrochemical reactions by a scanning electron microscope (SEM), a variety of techniques with a specifically designed electrochemical cell and electrolytes have been developed for observation of electrochemical metal deposition from RTIL in real time by SEM. Two types of cells were assembled; i.e. a platinum-coated glass slide whose surface was divided into three regions and a glass cell, which can be moved down during observation, except for the working electrode. A novel polymer composite material consisting of poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) and RTIL of 1-n-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) amide (BMI-TFSA) was prepared as a polymer gel electrolyte.
In situ microscopic-four-point probe conductivity measurements were performed for ultrathin bismuth (Bi) films formed on Si(111)-7×7. From the extrapolation of thickness-dependent conductivity and decrease in conductivity through surface oxidation, we found clear evidence of large surface-state conductivity (σss∼1.5×10−3 Ω−1/¿ at room temperature) in ultrathin Bi(001) films. For the thinnest films (∼25 Å), the transport properties are dominated by the surface states. The temperature dependence of the surface-state conductivity showed a metallic behavior down to 15K. These results point to the possibility to use these Bi surface states for spintronics device applications utilizing the largely Rashba spin-split properties.
Se-S exchange properties of hydrodeselenium (HDSe) reaction of selenophene on Co-Mo sulfide catalysts prepared by a CVD method were investigated on the basis of the amount of exchangeable sulfur atoms per active site and Co K-edge XAFS. The Co K-edge EXAFS for the CVD-Co/MoS2 catalysts after HDSe reaction was analyzed by a curve fitting method. EXAFS analysis revealed a relationship between the coordination numbers of Co-S and Co-Se shells and the number of incorporated selenium atoms per Co (Se/Co). The change of the coordination numbers of Co-S and Co-Se shells during the reaction are compatible with the dinuclear Co-Mo-S model previously proposed from EXAFS analysis and magnetic properties. A linear relationship was observed between the number of exchanged sulfur atoms per Co atom (H2S/Co) and the activity for thiophene HDS reaction, indicating that the HDS activity depends on the amount of exchangeable sulfur atoms in Co-Mo sulfide catalysts. It was also found that the amount of maximum exchangeable sulfur depends on the catalyst support and sulfidation conditions.
We have observed two type of bonding configuration of Iodobenzene (C6H5I) molecule upon room temperature adsorption on the Si(111)-7×7 surface and investigated an effect of Adsorbate-Electron interaction on a bonding configuration change of the Iodobenzene molecules on the Si(111)-7×7 surface using scanning tunneling microscope (STM). With the direct-current heating, a conversion rate of the bonding configuration as a function of the lattice temperature, K(Tl), has been determined. The plot of ln(K(T)) vs.T shows a deviation from a Arrhenius straight line, which suggests that the current accelerates the molecule's reaction by heating the adsorbate preferentially above the lattice temperature. Though tunneling current induced chemical reaction has been reported, we believe this is the first report of a direct observation that the interaction between an adsorbate and lattice current causes a chemical reaction.
In the case of measurement of Li Kα using by electron beam excitation, it was found that the detection of Li Kα of insulator compound, except LiF, was so difficult while the measurement of metallic Li was so easy. For this point, the examination with cluster calculation was carried out. From the results of the calculation, it was revealed that the detected Li Kα of LiF in our measurement was not original of LiF, but the Li which was reduced and changed to metallic state by the primary electron beam irradiation. And, the result of the calculation suggested that the conduction electron might be contribute to the dipole transition process and the generation of Kα, while the all of other valence electrons mainly relax to core level by Auger decay process.
Surface structures of rutile TiO2(114) have been studied by a combination of scanning tunneling microscopy (STM) and density functional calculations. Depending on the surface preparations, the surface exhibited various complicated structures. Microfaceting structural models can explain the experimental results very well. Calculated images for STM are in good agreement with the experimental results. The decrease of the density of dangling bonds stabilizes the surface energy, which results in the microfaceting reconstructions.
In order to grow multi-layer graphene for LSI interconnection at the low temperature without any catalyst, the growth temperature dependence of multi-layer graphene formed by photoelectron-assisted plasma chemical vapor deposition is investigated using microscopic Raman spectroscopy and bulk-sensitive X-ray photoelectron spectroscopy. The samples were grown at the temperatures from room temperature (RT) to 700oC by using an Ar/CH4 gas mixture on a Si(001) substrate with native oxide. At temperatures as high as 700oC, shiny black films are obtained, suggesting the growth of graphite. From G band position and FWHM in Raman spectra, it is found that the abundance of graphene sheet is considerably reduced when the growth temperature is lowered below 500oC, leading to an increase of amorphous. This tendency is in accordance with the temperature dependence of the ratio between amorphous graphene components in C 1s spectra.