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排序方式: 共有218条查询结果,搜索用时 15 毫秒
101.
Nagaoka S Matsumoto T Okada E Mitsui M Nakajima A 《The journal of physical chemistry. B》2006,110(32):16008-16017
The adsorption state and thermal stability of V(benzene)2 sandwich clusters soft-landed onto a self-assembled monolayer of different chain-length n-alkanethiols (Cn-SAM, n = 8, 12, 16, 18, and 22) were studied by means of infrared reflection absorption spectroscopy (IRAS) and temperature-programmed desorption (TPD). The IRAS measurement confirmed that V(benzene)2 clusters are molecularly adsorbed and maintain a sandwich structure on all of the SAM substrates. In addition, the clusters supported on the SAM substrates are oriented with their molecular axes tilted 70-80 degrees off the surface normal. An Arrhenius analysis of the TPD spectra reveals that the activation energy for the desorption of the supported clusters increases linearly with the chain length of the SAMs. For the longest chain C22-SAM, the activation energy reaches approximately 150 kJ/mol, and the thermal desorption of the supported clusters can be considerably suppressed near room temperature. The clear chain-length-dependent thermal stability of the supported clusters observed here can be explained well in terms of the cluster penetration into the SAM matrixes. 相似文献
102.
E. Suharyadi T. Hori M. Seto S. Kitao T. Mitsui Y. Yoda 《Journal of magnetism and magnetic materials》2010,322(1):158-162
Co2TiSn Heusler alloy films were grown on MgO substrates at the substrate temperature between 200 and 600 °C using atomically controlled alternate deposition and magnetic hyperfine field at the Sn nuclei was measured by the Mössbauer spectroscopy and the nuclear resonant scattering method. The relation between the hyperfine field and the structural disorder estimated by X-ray diffraction measurements was also examined. The results showed that the sample prepared at higher substrate temperature has higher degree of L21 order and larger hyperfine field. For the Co2TiSn film grown at 600 °C, the hyperfine field estimated from the oscillatory pattern of the nuclear resonant time spectra was 6.1 T at room temperature and increased with a decrease of temperature to 7.5, 8.1, and 8.3 T at 200, 100, and 5 K, respectively, which shows that the film prepared by this method and condition has almost the same magnetization value and Curie temperature as bulk samples. 相似文献
103.
Hidenori Otsuka Taketomo Sanbai Daisuke Matsukuma Yusuke Ikenaga 《Colloid and polymer science》2014,292(2):291-300
We have newly synthesized amphiphilic block copolymers composed of hydrophilic poly(ethylene glycol) (PEG) and hydrophobic pyridine segments (PEG-b-Py). Chain transfer agent-terminated PEG was subsequently chain-extended with 3-(4-pyridyl)-propyl acrylate to obtain PEG-b-Py by reversible additional-fragmentation chain transfer polymerization. Particularly, the effect of varying molecular weight (Mn) of PEG (Mn?=?2,000 and 5,000) and Py in the block copolymers was investigated in terms of critical micelle concentration, pyrene solubilization, micelle size distribution, and association number per micelle. Based on the amphiphilic balance, PEG-b-Pys formed core-shell type polymer micelle. The association number of PEG2k-b-Py was higher than that of PEG5k-b-Py, suggesting the degree of phase separation strongly depended on PEG Mn. Furthermore, the adsorption of PEG-b-Py copolymer onto silica nanoparticles as dispersant was studied to estimate the effect of PEG Mn in the copolymers and their solubility in the medium on the adsorption. Adsorbed density of PEG2k-b-Py copolymer onto silica nanoparticle was higher than that of PEG5k-b-Py, which was significantly correlated with the degree of phase separation. Furthermore, the adsorbed amount of copolymer increased with the increase in ionic strength due to the reduced solubility of PEG in the buffer solution. The resultant dispersion stability was highly correlated with the graft density of copolymer onto silica surface. However, the stability of PEG2k-b-Py coated particles was lower than that with PEG5k-b-Py, this is attributed to the relatively thin layer of PEG at the silica surface, which cannot provide the system with sufficient steric stabilization as the salt concentration increases. These fundamental investigations for the surface modification of the nanoparticle provide the insight into the highly stable colloidal dispersion, particularly in the physiological condition with high ionic strength. 相似文献
104.
105.
M. Mitsui Y. Matsumoto N. Ando A. Nakajima 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,34(1-3):169-172
Cluster anions of 2,2’-bithiophene, (2T)n-, were produced up
to n ∼500 in the gas-phase. The energetics of the excess electron in
the (2T)n- clusters with n =1-100 were explored by
negative ion photoelectron spectroscopy. When the vertical detachment
energies (VDEs) obtained from the photoelectron spectra were analyzed by a
plot against n-1/3, it has been revealed that the excess electron
trapping level thus extrapolated is located at ∼0.8 eV below the
conduction band minimum (i.e. LUMO) of the 2T thin film. The large slope of
the VDEs vs. n-1/3 plot suggests that the neutral 2T molecules
surrounding the anion core take non-planar twisted conformations with
permanent dipole moments, resulting in the exceedingly deep trapping of the
excess electron in the 2T cluster anions. 相似文献
106.
Matsuoka T Fujihisa H Hirao N Ohishi Y Mitsui T Masuda R Seto M Yoda Y Shimizu K Machida A Aoki K 《Physical review letters》2011,107(2):025501
Europium hydride EuH(x), when exposed to high-pressure H?, has been found to exhibit the following structural and valence changes: Pnma(x = 2, divalent) → P6?/mmc(x = 2, 7.2-8.7 GPa) → I4/m(x > 2, 8.7-9.7 GPa) → I4/mmm(x > 2, 9.7 GPa-,trivalent). With a trivalent character and a distorted cubic fcc structure, the I4/mmm structure is the β phase commonly observed for other rare-earth metal hydrides. Our study clearly demonstrates that EuH(x) is no longer an irregular member of the rare-earth metal hydrides. 相似文献
107.
Ko Mibu Makoto Seto Takaya Mitsui Yoshitaka Yoda Ryo Masuda Shinji Kitao Yasuhiro Kobayashi Edi Suharyadi Masaaki Tanaka Masakiyo Tsunoda Hideto Yanagihara Eiji Kita 《Hyperfine Interactions》2013,217(1-3):127-135
Applications of synchrotron-radiation-based Mössbauer spectroscopy in the “energy domain” to the studies on magnetism of thin films are introduced on the basis of the experiments recently performed at SPring-8, Japan. The measured samples are spintronics-related thin films, such as Co2MnSn films, layered Fe/Cr films, layered Fe/Fe3O4 films, and Fe4N films. The validity of the energy domain measurements is demonstrated in the light of industrial applications of magnetic thin films. 相似文献
108.
Kentaro Mitsui 《Mathematische Zeitschrift》2014,276(1-2):237-242
We give a new method to construct unirational surfaces which may be applied to the following question posed by Zariski in his studies on unirational surfaces. Is any Zariski surface with geometric genus zero rational? Our main result is a negative answer to this question in any characteristic case. 相似文献
109.
We demonstrate the formation of nanoscale volcano-like structures induced by ion-beam irradiation of nanoscale pores in freestanding silicon nitride membranes. Accreted matter is delivered to the volcanoes from micrometer distances along the surface. Volcano formation accompanies nanopore shrinking and depends on geometrical factors and the presence of a conducting layer on the membrane's back surface. We argue that surface electric fields play an important role in accounting for the experimental observations. 相似文献
110.
Implicit Runge-Kutta methods with vanishingM matrix are discussed for preserving the symplectic structure of Hamiltonian systems. The number of the order conditions independent of the number of stages can be reduced considerably for the symplectic IRK method through the analysis utilizing the rooted tree and the corresponding elementary differentials. Butcher's simplifying condition further reduces the number of independent order conditions. 相似文献