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831.
Performance characteristics of narrow linewidth fiber laser pumped mid-IR difference frequency mixing light source for methane detection. 总被引:2,自引:0,他引:2
Hiroaki Ashizawa Shinobu Ohara Shigeru Yamaguchi Masao Takahashi Masamori Endo Kenzo Nanri Tomoo Fujioka Frank K Tittel 《JAPANESE JOURNAL OF APPLIED PHYSICS》2003,42(3):1263-1267
A high-power, narrow-linewidth Yb fiber laser with a fiber Bragg grating (FBG) pumped difference frequency generation (DFG) in a periodically poled lithium niobate (PPLN) crystal was investigated in detail. A mid-IR power of approximately 2.3 microW at 3.3 micrometers with a slope efficiency of 0.85 mW/W2 was achieved. A Doppler-broadened absorption spectrum of CH4 at 3038.497 cm-1 (3.2911 micrometers) was obtained with a 0.1-m long-gas cell at a pressure of 133 Pa. The linewidth of the DFG source was evaluated to be less than 96 MHz from the observed spectral linewidth. Real-time monitoring of CH4 (approximately 1.78 ppm) in ambient air in a multipass cell which has an optical path length of 10 m was also demonstrated. 相似文献
832.
Recently, deeply bound pionic states were found experimentally in (d,3He) reactions on208Pb. They found an isolated peak structure in the bound region below the pion production threshold. We study theoretically these excitation functions in (d,3He) reactions on208Pb at T d =600 MeV. We found very good agreement with the (d,3He) excitation functions and could identify the underlying structures of the pionic states. We study the energy dependence of the (d,3He) reactions and the change of the excitation functions with the incident energy. 相似文献
833.
S. Ishio M. Fujikura T. Ishii M. Takahashi 《Journal of magnetism and magnetic materials》1986,60(2-3):236-242
The magnetic and mechanical properties of amorphous Fe100−xYx alloys (20 ≤ x ≤ 60) fabricated by rapid quenching have been measured. The dependence of the density, Young's modulus and magnetic moment per Fe atom on x shows a break point between x = 30 and 40, accompanied by a drastic change in the X-ray diffraction pattern. The spontaneous volume magnetostriction as well as the forced volume magnetostriction are a maximum at x = 20 and decrease rapidly with increasing x. The variation of the magnetic and mechanical properties with x is explained by a change of the local atomic arrangement in the amorphous state, reflecting the structure of corresponding crystalline compounds. 相似文献
834.
J. Akimitsu H. Okajima A. Yamashita K. Ishii T. Yokoo T. Nagata M. Uehara R. Kadono K. Nagamine N. Kobayashi Z. Hiroi M. Takano H. Takahashi N. Mori K. Kinoshita 《Hyperfine Interactions》1997,104(1-4):43-48
We report here the two current topics in the ladder compounds.
1. The new ladder compound LaCuO2.5 recently discovered by Hiroi and Takano shows a clear sign of magnetic long range order at around 125 K observed by μ+SR technique. This result demonstrates that the ground state of LaCuO2.5 is not a spin liquid state, but a magnetically ordered state.
2. Superconductivity has been found in the ladder material (Sr,Ca)14Cu24O41 under high pressure between 3 GPa and 4.5 GPa. The superconducting transition temperatures Tc (onset) are 12 K and 9 K at 3 GPa and 4.5 GPa, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
835.
Yoshihiro Tsuda Kohshin Takahashi Takahiro Yamaguchi Syuichi Matsui Teruhisa Komura 《Journal of molecular catalysis. A, Chemical》1998,130(3):244-295
When a viologen-linked Mn(III)porphyrin complex with a short methylene-chain, in which a viologen is covalently linked by the methylene-chain into one phenyl group of 5,10,15,20-tetraphenylporphyrinatomanganese(III)chloride (Mn(III)(tpp)Cl), was used as a catalyst for a monooxygenation of cyclohexene in an air-equilibrated acetonitrile solution containing insoluble zinc powder as a reductant, more cyclohexene oxide was obtained as a single product than when Mn(tpp)Cl was used as a catalyst. Benzoic acid as a cleaving reagent of the dioxygen double-bond and 1-methylimidazole as a ligand to Mn porphyrin were further contained in the reaction mixture. This result implies that the viologen moiety in the viologen-linked Mn(III)porphyrin acted effectively as a mediator for electron transfer from zinc powder to the Mn(III)porphyrin moiety in the epoxidation cycle activating molecular dioxygen reductively. Though Mn(tpp)Cl was remarkably demetallated by H+ ion from benzoic acid during the epoxidation reaction in the mixed system of Mn(III)(tpp)Cl and viologen, the demetallation of the viologen-linked Mn porphyrin with the short methylene-chain was partly prevented because the reduction of a Mn(II)porphyrin-dioxygen adduct was easily caused by fast intramolecular electron-transfer between the two moieties of the viologen and the Mn porphyrin, proceeding the epoxidation cycle smoothly. 相似文献
836.
Ultrafine particles (UFP) of six kinds of FeNi alloys were synthesized by the method of hydrogen plasma reaction. The prepared UFP samples were examined by X-ray diffraction, electron transmission microscopy and magnetic measurement. The spherical FeNi UFP alloys with a mean particle size less than 35 nm can be prepared with a production rate much higher than by conventional methods. The phase constitution of UFP alloys is different from the equilibrium phase diagram owing to rapid condensation of evaporated metal gases. Although the magnetization for the UFP alloys has almost the same temperature dependence as that of the bulk alloys, the saturation magnetization remarkably decreases as the bulk alloys change into the UFP alloys. 相似文献
837.
T Kojima K Niigata T Fujikura S Tachikawa Y Nozaki S Kagami K Takahashi 《Chemical & pharmaceutical bulletin》1985,33(9):3766-3774
838.
Keiko Takahashi Kenjiro Hattori 《Journal of inclusion phenomena and macrocyclic chemistry》1994,17(1):1-24
Cyclodextrins have great potential for exploitation as a useful tool for asymmetric induction. Many kinds of asymmetric reaction have been achieved in the presence of cyclodextrin under various conditions such as the solid phase, heterogeneous suspension or homogeneous aqueous or organic solution. Complexation is essential for asymmetric induction. What is necessary to improve CDs for greater asymmetric induction? 相似文献
839.
A joint-transform phase correlation is made by an extracted phase from the joint power spectrum using a phase-shifting Mach-Zehnder
interferometer with a wavelength-shifted laser diode (LD), and then by numerically Fourier-transforming a measured phase.
The algorithm in six steps is insensitive to the power changes in an LD. The phase correlator gives the best discrimination
performance. Discriminative multiple-object recognition is performed with no intermodulation noise and artifact noise-free
correlation by arranging the multiple objects in a regularly equal-spaced array. The experimental and numerical results are
shown. 相似文献
840.
Kazuhiko Ishikawa Hitomi Yamano Ki-ichiro Kagawa Katsuhiko Asada Koichi Iwata Masahiro Ueda 《Optics and Lasers in Engineering》2004,41(1):19-29
An optical method for directly measuring the thickness of a thin transparent film has been proposed by means of multi-wave laser interference at many incident angles, and confirmed experimentally by means of equipment made on an experimental basis. Two methods are available: one can be used when an index of refraction of the film, a wavelength λ, and two successive angles of incidence at which the sinusoidal light intensity has minimum values, are known (Method I), and another can be used without an index of film refraction when three successive angles of incidence and a wavelength are known (Method II). The smallest measurable thickness is 1.43λ for Method I, and 2.5λ for Method II. The largest measurable thickness is about 100λ for both methods. The measurement error by means of numerical calculation is Δh/h−1.01×10−2, and that obtained experimentally with an angular resolution of incident light of 0.3° is Δh/h7×10−2 for Method I. The refractive index can also be measured by means of Method II. 相似文献