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81.
The fast potential change near the separatrix is measured directly at the L-H transition by a heavy-ion-beam probe. The potential changes with two different time scales at the L-H transition triggered by a sawtooth crash: it drops at first with the time scale of 10--100 mus just after the arrival of the heat pulse due to the sawtooth crash. Then, it decreases again at a few 100 mus after the first drop at a time scale of about 200 mus. 相似文献
82.
83.
Infrared femtosecond laser pulse induced permanent reduction of Eu3+ to Eu2+ in a fluorozirconate glass 总被引:3,自引:0,他引:3
We report what is believed to be the first observation of permanent photoreduction of Eu(3+) to Eu(2+) in transparent and colorless Eu(3+) -doped fluorozirconate glass at room temperature, using an infrared femtosecond laser. Difference absorption and electron-spin-resonance spectra of the glass before and after laser irradiation showed that a portion of the Eu(3+) ions in the focused part of the laser inside the glass were reduced to Eu(2+) ions after laser irradiation. It is suggested that Eu(3+) ions act as electron-trapping centers, whereas active sites in the glass matrix act as hole-trapping centers, leading to the formation of Eu(2+) ions. The observed phenomenon is inferred to be useful in the fabrication of optical memory devices with high storage density and waveguide-type micro-optical devices. 相似文献
84.
Infrared cyclotron resonance was observed in n-type InSb, GaAs and Ge in very high magnetic fields up to 1.3 MOe at room temperature using a CO2 laser. A large shift of the cyclotron mass due to the non-parabolicity of the energy band was found in each material. The band edge masses of electrons at room temperature were evaluated to be for InSb, m for GaAs and m for Ge. The linewidth was measured in GaAs and Ge in the high fields. 相似文献
85.
The quantum oscillations in the AC magnetoconductance was studied for inversion layers in Si-MOS-FETs under high magnetic fields at 1.5 K. Each peak in the Shubnikov-de Haas oscillation was found to be remarkably sharpened with increasing frequency up to 50 MHz. It was also found that the width of the gate voltage for non-conductive region (σxx=0) increases with increasing frequency. 相似文献
86.
Thalacker C Miura A De Feyter S De Schryver FC Würthner F 《Organic & biomolecular chemistry》2005,3(3):414-422
A series of red and blue highly fluorescent core-substituted naphthalene bisimide dyes has been synthesized and they have been investigated as supramolecular building blocks. NMR and UV-Vis titration experiments of these dyes with complementary melamines revealed the formation of triple hydrogen bonds (DAD-ADA arrays) in solution. At stoichiometric ratios, ditopic melamine receptors could dissolve otherwise insoluble bisimides by means of hydrogen bonding, even in aliphatic solvents. At the solution/graphite interface, one-dimensional chains of hydrogen bonded naphthalene bisimides and two-dimensional adlayers of ditopic melamines are formed for the pure compounds but little evidence for heterocomplexes between the two complementary building blocks could be obtained. 相似文献
87.
Nagashima Y Hoshino K Ejiri A Shinohara K Takase Y Tsuzuki K Uehara K Kawashima H Ogawa H Ido T Kusama Y Miura Y 《Physical review letters》2005,95(9):095002
Two types of electrostatic modes with small-poloidal wave numbers (approximately 1 and 10-15 kHz) are observed in the edge region of Ohmically heated plasmas in the JFT-2M tokamak. The envelope of the higher frequency coherent mode is modulated at the frequency of the lower frequency mode. A bispectral analysis revealed that a significant nonlinear coupling among the two types of fluctuations and the broadband background turbulent potential fluctuations occurs inside the last closed magnetic flux surface, suggesting that a nonlinear process such as the parametric-modulational instability is involved. 相似文献
88.
We describe the fabrication and evaluation of a low-loss, high-delta optical waveguide consisting of heterostructured photonic crystals. The waveguide is composed of a multilayer stack of Ta2O5/SiO2 and is prepared by use of the autocloning technique. Light is guided in the waveguide by the difference in the effective refractive indices of the constituent photonic crystals. By improving the design of the core region so that is has a flat multilayer structure, we achieve delta = 3.09% for the in-plane direction and net propagation loss of 0.56 dB/mm at lambda = 1.6 microm. Experiments also suggest that the bending loss of the waveguide can be reduced to less than 0.1 dB if the curvature radius is larger than 700 microm. 相似文献
89.
90.
Okamura H Kawahara J Nanba T Kimura S Soda K Mizutani U Nishino Y Kato M Shimoyama I Miura H Fukui K Nakagawa K Nakagawa H Kinoshita T 《Physical review letters》2000,84(16):3674-3677
Optical conductivity data of the intermetallic compounds (Fe1-xVx)3Al ( 0=x=0.33) reveal that their density of states around the Fermi energy ( E(F)) is strongly reduced as x is increased. In particular, Fe2VAl ( x = 0.33) has a deep, well-developed pseudogap of 0.1-0.2 eV at E(F) and a small density ( approximately 5x10(20) cm(-3)) of carriers, which is highly unusual for intermetallic compounds. It is shown that the pseudogap results from the band structure of Fe2VAl, rather than from temperature-dependent correlation effects. Based on the present results, we propose a simple model that consistently explains both the semiconductorlike transport and the metallic photoemission results previously observed for Fe2VAl. 相似文献