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51.
The transition structures of the thione-to-thiol rearrangement of O-(2-dimethylaminoethyl and 2-methylthio-) S-methyl xanthates in several solvents were located by semiempirical molecular orbital method (PM3) using the conductor-like screening model (COSMO) approach. Each transition state transforms into the ion-pair intermediate with a three-membered ring structure (aziridinium or thiiranium), indicating that the rearrangement proceeds through an ionic intermediate with the anchimeric assistance of the neighboring group. The intermediary structures in gas phase are also analyzed by ab initio and density functional theory calculations. 相似文献
52.
Michiko Yoshitake Michal Vaclavu Mykhailo Chundak Vladimir Matolin Toyohiro Chikyow 《Journal of Solid State Electrochemistry》2013,17(12):3137-3144
A thin epitaxial CeO2 film was grown on a Cu(111) single crystal in order to investigate the mechanism of resistive memory/switching devices with an ultimately thin high-k dielectric film. A small amount of Pt was deposited on the CeO2 film and the Pt/CeO2/Cu structure was characterized by conductive atomic force microscopy and X-ray photoelectron spectroscopy. It was found that the grown epitaxial CeO2 film was fully oxidized, i.e., the valence of Ce atoms in the film was completely Ce4+. However, after the deposition of a small amount of Pt, it was revealed that Ce atoms were partially reduced to Ce3+ in full thickness of the film. The Pt/CeO2/Cu structure did not show switching behavior in resistance. The observed reduction of CeO2 film is considered to be responsible to the non-switching behavior. The thermodynamics of the reduction of the CeO2 film and the kinetics of oxygen diffusion in the reduced CeO2 film are discussed. 相似文献
53.
54.
Y. Murakami H. Kido A. Kenjo T. Sadoh T. Yoshitake M. Miyao 《Physica E: Low-dimensional Systems and Nanostructures》2003,16(3-4):505
Effects of Ar+ ion-beam irradiation on solid-phase growth of β-FeSi2 have been investigated. Fe (10 nm)/Si structures were irradiated with 25 keV Ar+ (5.0×1015 cm−2) at a temperature of 25°C (sample A) or 400°C (sample B), and subsequently annealed at 800°C. A reference was obtained after annealing without irradiation (sample C). X-ray diffraction results indicated that β-FeSi2 was formed after annealing at 800°C for 5 h, and the formation rate was the fastest for sample A and the slowest for sample C, i.e., A>BC. However, Auger electron spectroscopy measurements showed that atomic mixing at Fe/Si interface before annealing was B>AC. These results suggested that amorphization of Si substrate, in addition to atomic mixing, enhanced the solid-phase growth of β-FeSi2, which was confirmed experimentally. Moreover, a direct band gap of 0.89 eV was observed for the sample with pre-amorphization by the Fourier-transform infrared (FT-IR) spectroscopy measurements. These enhancement effects were attributed to that the phase transition to β-FeSi2 was accelerated by atomic arrangement induced during annihilation of excess vacancies. These enhancement effects can be utilized for nano-fabrication of β-FeSi2 by using focused ion-beam irradiation. 相似文献
55.
56.
Hu X Masuda Y Ohji T Kato K 《Langmuir : the ACS journal of surfaces and colloids》2008,24(14):7614-7617
Micropatterns of ZnO nanoarrays were simply and successfully fabricated in an aqueous solution without any high-temperature treatment and/or expensive catalyst. In situ forced hydrolysis of patterned anhydrous zinc acetate, derived by ultraviolet irradiation with a photomask, resulted in heterogeneous nucleation and growth to form ZnO nanoarrays. Micropatterns of ZnO nanoarrays were characterized by FE-SEM and XRD. ZnO nanoarrays were well site-selectively deposited on anhydrous zinc acetate coated regions at 88 degrees C. HR-TEM clarified the formation mechanism in which anhydrous zinc acetate showed a tendency of forced hydrolyzation to ZnO nanocrystals at the initial stage in the reaction solution. 相似文献
57.
Tsukube H Noda Y Kataoka Y Miyake H Shinoda S Kojima-Yuasa A Nishida Y Matsui-Yuasa I 《Dalton transactions (Cambridge, England : 2003)》2008,(30):4038-4043
A series of oligopyridine ligands were derived from amino acid amides in which amide oxygen and ternary nitrogen atoms were combined with pyridine moieties. 1H NMR and circular dichroism spectroscopic characterizations revealed that they formed stable Zn2+ complexes in neutral aqueous solutions and caused Zn2+ deficiency in the hepatic stellate cell systems. Since collagen synthesis was effectively promoted in the cells, the present oligopyridine derivatives worked as biocompatible ligands for Zn2+ complexation and cell activation. 相似文献
58.
The reaction of pentathienoacene (f-5T) with mCPBA produced a series of oxidized derivatives containing one or two thiophene- S, S-dioxide rings. The regioselectivity of the oxidation reflects the aromaticity of each thiophene ring in the f-5T skeleton, and the extent of the oxidation significantly affects the fluorescence and redox properties. 相似文献
59.
Mykhailo Chundak Michiko Yoshitake Michal Vaclavu Vladimir Matolin Toyohiro Chikyow 《Journal of Solid State Electrochemistry》2017,21(3):657-664
We investigate the introduction of oxygen vacancies by the interaction of Pt with CeO2(111) (ceria) thin epitaxial film grown on Cu(111) and the influence of the vacancies on resistive switching behavior. For this purpose, we used X-ray photoelectron spectroscopy and conductive atomic force microscopy. We found out that after Pt deposition, the ceria film was partially reduced. By our estimation, the reduction occurs not only at the Pt/CeO2 interface, but also on the surface of the ceria film which is not covered by Pt, after Pt deposition and annealing. A different distribution of oxygen vacancies in the film proves to have an influence on the resistance switching process of the film. Finally, the proper balance between the reduced and the unreduced species in order to obtain relatively stable repeatable resistance switch with clear resistance window is discussed. 相似文献
60.
Room temperature-stable inorganic electride [Ca(24)Al(28)O(68)](4+)4e(-) was employed for a pinacol coupling reaction in aqueous media. Ca-Al-O gel formed by the destruction of the crystal structure of an electride by water media played a key role in transferring the electron to electrophilic aldehydes. Aromatic aldehydes reacted smoothly with moderate to high yields. 相似文献