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151.
Abstract The viscosity dependence of the isomerization process with comparatively low potential barrier was studied as a model of one-dimensional barrier crossing. We found that the ground-state isomerization of DODCI fails to fit the Kramers equation. We analyzed this non-Kramers behavior by means of an approach of frequency dependent friction. 相似文献
152.
Nobuo Ogata Teruaki Yanagawa Koukichi Yoshida 《Journal of Polymer Science.Polymer Physics》1986,24(9):1917-1929
Fracture mechanics was used to investigate the environmental stress cracking (ESC) of low density polyethylene (LDPE). Annealed and quenched samples were prepared; a single edge notch was made and the samples were fractured under constant load in a liquid methanol environment. The relation between the stress intensity factor K and the crack speed ? has been investigated. There is a large difference between annealed and quenched samples in the variation of this relation with temperature and applied load. The cause of this difference is discussed in detail. We propose that thermally activated molecular motion is essential to ESC of the annealed LDPE while stress concentration contributes markedly to ESC of the quenched LDPE. 相似文献
153.
Kazunari Ozasa Shigeyuki Nemoto Mizuo Maeda Masahiko Hara 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):89
We have found that the photoluminescence (PL) intensity of CdSe/ZnS nanocrystals placed on a thin film of insulator (GaAsOx/GaAs) depends on excitation wavelength through the interference effects of the excitation light. By employing the multi-reflection/interference calculation, the insulator thickness of the underlying non-uniform patterns can be evaluated by the simple observation of CdSe/ZnS PL with a couple of excitation wavelengths. Moreover, the differences observed for the temporal evolution of CdSe/ZnS PL (blue shifts and degradation) among the excitation wavelengths suggest that the photo-induced changes of chemical composition and surface ligands are responsible for blue shifts and degradation, respectively. 相似文献
154.
Hidenori Okuzaki Takui Takahashi Yusuke Hara Hu Yan 《Journal of Polymer Science.Polymer Physics》2008,46(3):305-310
Unlike conventional electrospun polymer fibers deposited on a target electrode as a randomly oriented mesh, poly(p‐xylenetetrahydrothiophenium chloride) was electrospun into centimeters‐long yarns vertically on the surface of the electrode but parallel to the electric field. The diameter of the yarn was strongly affected by the concentration, spinning rate, and viscosity of the polymer solution, but less dependent on the applied voltage. The subsequent carbonization of thus‐electrospun yarns at 600–1000 °C resulted in uniaxially aligned carbon nanofibers with average diameters of 127–184 nm. On the basis of Raman spectra, the graphitic crystallite size and the molar fraction of graphite were estimated to be 1.2–1.4 and 0.21–0.24 nm, respectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 305–310, 2008 相似文献
155.
We observed the surface morphology of vicinal GaAs(001) after thermal treatment in AsH3/H2 atmosphere by atomic force microscopy (AFM). Clear multiatomic steps were formed under the high temperature thermal treatment. Next, we investigated the mechanism of step bunching during thermal treatment by two experiments from the view point of Ga atom evaporation. One is the selective thermal treatment using a partially masked GaAs wafer, and the evaporation amount of Ga atoms was estimated by AFM. The other is the investigation of photoluminescence (PL) peak energy shifts for AlGaAs/GaAs single quantum wells with a thermal treatment process at the top of the GaAs quantum well layer, compared to those without thermal treatment. These results indicate that the evaporation hardly occurs during the thermal treatment process. Therefore, step bunching phenomena on GaAs(001) vicinal surfaces during thermal treatment are probably caused by migration of the atoms detached from upside steps and their re-incorporation to downside steps. 相似文献
156.
Shinsaku Dobashi Masaharu Kira Ryuichiro Tanaka Yoshinori Izawa Akihide Wada Michikazu Hara 《Analytical sciences》2006,22(4):603-606
The development of molecular spectroscopy has enabled us to select chlorinated aromatic hydrocarbons very rapidly. In particular, the laser ionization TOFMS (time-of-flight mass spectrometry) method is expected to be useful as an on-line, selective, and sensitive method. In the present work, real-time laser ionization TOFMS measurements were carried out on gaseous chlorinated aromatic hydrocarbons. The laser ionization method used resonance-enhanced two-photon ionization with the direct introduction of gas into the vacuum chamber. This method for analyzing aromatic hydrocarbons was developed using a pulsed supersonic molecular beam method. In the context of developing a highly selective and sensitive method, excitation of monochlorinated benzene at lambda = 263.07 nm was found to be effective in the wavelength region from 263 nm to 265 nm. Also the excitation of polychlorinated biphenyls at lambda = 266 nm was found to be substantially more effective than at lambda = 280, 300 or 320 nm. The achievable sensitivity for real-time (1 min) measurements using the laser ionization TOFMS technique was found to be in the ppbV range. 相似文献
157.
C. P. Slichter S. E. Barrett J. A. Martindale D. J. Durand C. H. Pennington C. A. Klug K. E. O’Hara S. M. DeSoto T. Imai J. P. Rice T. A. Friedmann D. M. Ginsberg 《Applied magnetic resonance》1992,3(3-4):423-448
The authors review and up-date their work on Knight shifts, spin-lattice relaxation, and indirect nuclear spin-spin coupling for YBa2Cu3O7 in the superconducting state. The data are analyzed in particular to show what it may indicate about the orbital and spin pairing of the superconducting state. 相似文献
158.
Highly efficient processes for fine particle formation of metal alloys and metal oxides were developed using a high-power laser. In these processes, laser light was used only for the ignition of a thermal chain reaction. This reaction was suppressed by adding inert gases, and the suppression effect was in the order C3H8 > C2H6 > CH4 > He > Ar > Xe. Oxygen accelerated the reaction because of the large exothermicity of the reaction of oxygen with methyl metal compounds. 相似文献
159.
160.
Nobuo Inagaki 《Annals of the Institute of Statistical Mathematics》1994,46(4):633-640
The maximal operator plays the similar role as the summation operator in the sense of stability of operation. So, we could discussARMA processes in the maximal operation by the same way as in the summation operation. However, many papers already treated with moving order statistics. In this paper, we discuss asymptotic behaviors of maximal autoregressive (MAR) processes with the weight tending to 1. 相似文献