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151.
Norihiko Hayazawa Taka‐aki Yano Satoshi Kawata 《Journal of Raman spectroscopy : JRS》2012,43(9):1177-1182
We have successfully improved the reproducibility of tip‐enhancement effect on metallized silicon cantilever tips for characterization of carbon nanotubes. Plasmon resonance tuning relative to an excitation wavelength is crucial for efficient tip‐enhancement, which is accomplished by thermal oxidization and subsequent metallization of commercial silicon tips. Because of the change of the refractive index of the tip from silicon to silicon dioxide, the plasmon resonance of the silver‐coated tip is blue‐shifted showing an enormous enhancement at 532 nm excitation. Highly reproducible tips exhibit an enhancement factor of >100 with a 100% yield. Because the tips are fabricated from commercially available silicon cantilever tips in a simple and robust way, our approach provides an important step of ‘tip‐enhanced Raman spectroscopy for everyone’. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
152.
Rahman MT Fukuyama T Kamata N Sato M Ryu I 《Chemical communications (Cambridge, England)》2006,(21):2236-2238
A low pressure microflow system was developed for palladium-catalyzed multiphase carbonylation reactions in an ionic liquid. The microflow system resulted in superior selectivity and higher yields in carbonylative Sonogashira coupling and amidation reactions of aryl iodides compared to the conventional batch system. 相似文献
153.
Electrons and holes were injected selectively into poly-2,7-(9,9-dihexylfluorene) (pF) dissolved in a tetrahydrofuran (THF) and a 1,2-dichloroethane (DCE) solution, respectively, using pulse radiolysis. Transient absorption spectra of monoions of both signs revealed two bands attributable to formation of polarons, one in the visible region (pF+* at 580 nm, pF-* at 600 nm) and another in the near-IR region. Additional confirmation for the identification of pF+* and pF-* comes from bimolecular charge-transfer reactions, such as bithiophene-* + pF --> pF-* or pF+* + TTA --> +TTA+* (TTA = tri-p-tolylamine), in which known radical ions transfer charge to pF or from pF. Difference absorption spectra of pF chemically reduced by sodium in THF provided a ratio of absorbance of anions formed to bleaching of the neutral band at 380 nm. In conjunction with pulse-radiolysis results, the data show that each polaron occupies 4.5 +/- 0.5 fluorene units, most probably contiguous units. Extensive reduction of pF by sodium also revealed resistance to formation of bipolarons: excess electrons reside as separate polarons when two or more electrons were injected. Redox equilibria with pyrene and terthiophene by pulse radiolysis established reversible one-electron redox potentials of E0(pF+/0) = +0.66 V and E0(pF0/-) = -2.65 V vs Fc+/0. Together with the excited-state energy, these results predict a singlet exciton binding energy of 0.2 eV for pF in the presence of 0.1 M tetrabutylammonium tetrafluoroborate. This binding energy would increase substantially without an electrolyte. 相似文献
154.
Depending on each nitrogen atom of adenine molecule to which a silver atom of a metallic tip approaches, tip-enhanced near-field Raman spectroscopy may show a potential to achieve atomic site-selective detection sensitivity. Molecular vibrational calculations show that silver atoms and adenine molecule create several isomers generating specific vibrational modes of each isomer that are shifted or not observable in isolated adenine molecule itself. Here, the authors observe the specific vibrational modes and spectral shifts of isomers experimentally and are in good agreement with their calculations. 相似文献
155.
We demonstrate quasi-supercontinuum (quasi-SC) generation around the 1.3 μm wavelength region using ultrahigh-speed, wavelength-tunable, femtosecond soliton pulses based on an ultrashort-pulse laser system operating at a wavelength of 1.0 μm. The wavelength tuning range was from 1.0 to 1.9 μm, and the scanning speed was up to 1.3 MHz. A Gaussian-like quasi-SC with a bandwidth of 220 nm was generated at 1220 nm. The generated quasi-SC was used in an optical-coherence tomography system. High axial resolutions of 5.1 μm in air and 3.7 μm in tissue were obtained. A maximum sensitivity of 100 dB was achieved, and ultrahigh-resolution images of a hamster cheek pouch were observed. 相似文献
156.
Facile One‐Pot Synthesis of [1, 2, 3]Triazolo[1, 5‐a]Pyridines from 2‐Acylpyridines by Copper(II)‐Catalyzed Oxidative NN Bond Formation 下载免费PDF全文
Dr. Tasuku Hirayama Dr. Satoshi Ueda Takahiro Okada Norihiko Tsurue Prof. Kensuke Okuda Prof. Hideko Nagasawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(14):4156-4162
An efficient and simple method for the synthesis of various [1, 2, 3]triazolo[1, 5‐a]pyridines has been established. The method involves a copper(II)‐catalyzed oxidative N?N bond formation that uses atmospheric oxygen as the terminal oxidant following hydrazonation in one pot. The use of ethyl acetate as the solvent dramatically promotes the oxidative N?N bond‐formation reaction and enables the application of oxidative cyclization in the efficient one‐pot reaction. A mechanism for the reaction was proposed on the basis of the results of a spectroscopic study. 相似文献
157.
Fluoro-dediazoniation of aromatic diazonium ions, produced by the diazotization of the corresponding aromatic amines with NaNO2 in anhydrous hydrogen fluorides (AHF) - organic base solutions, was accelerated photochemically to afford Ar-F efficiently in AHF - organic base solutions in situ. 相似文献
158.
Eiji Hayashi Yoshinori Furukawa Yukio Takahashi Hironori Itoh Norihiko Yoneda 《合成通讯》2013,43(13):2029-2036
1,4-Dibenzylbenzene was successfully synthesized by the Friedel-Crafts benzylation of benzene with 1,4-bis(chloromethyl)benzene using zinc chloride in the presence of polar solvents. In particular, zinc chloride dissolved in primary alcohols or ketones with a molar ratio of 1 was a highly effective catalytic system in the reaction. 相似文献
159.
The selective carboxylation of acyclic tert-aliphatic alcohols was successfully performed to produce the corresponding acyclic tert-aliphatic carboxylic acids in significantly high yields using concentrated sulfuric acid supersaturated with carbon monoxide. 相似文献
160.
The performance characteristics of generated soliton and anti-Stokes pulses for the wavelength tunable ultrashort soliton pulse generation system are discussed for different fiber dispersion parameters of β2 and β3 at the pump wavelength. Numerical analysis showed that the broadband wavelength tunability is improved as both the absolute value of negative β2 and the value of β3 are decreased. When β3 is the usual value, the best performance of broadband continuous wavelength tunability which broadens symmetrically to the pump wavelength is obtained for β3 of around 蜢2 psβ2/km. The reason for this is that the behaviors of both the generated soliton and anti-Stokes pulses are due to the β2. Through simulations for different fiber dispersion parameters of β2 or β3 we obtained interesting results. When β3 is negative and the zero dispersion wavelength is set at the longer wavelength side than the pump wavelength, such as around 2 μm, it is possible to convert the generated soliton into new components at the longer wavelength side over 2 μm. 相似文献