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151.
Exchange force of a ferromagnetic Fe probe on antiferromagnetic NiO(0 0 1) surface has been investigated by means of a first-principles calculation. Calculated exchange force images show a clear spin image when the probe is located within 1 Å above the contact point. We can see antiferromagnetic pattern of the surface Ni atoms along the [1 1 0] direction, and asymmetric feature around surface O sites. The main contrast of Ni comes from the direct exchange interaction between the Fe probe and the surface Ni atom, while the asymmetric image possibly comes from the super exchange interaction between the Fe probe and the second layer Ni atom via the surface O. Such asymmetric feature is a key proof of the exchange force microscope image on observation. 相似文献
152.
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154.
Hydrosilylation of styrenes bearing β-substituents with trichlorosilane was catalyzed by a palladium complex (0.1 mol %) coordinated with (R)- 2-methoxy-2′-diphenylphosphino-1,1′-binaphthyl ((R)-MeO-MOP) to give high yields of optically active 1-aryl-1-silylalkanes (80–85% ee) as single regioisomers. The resulting silanes were readily converted into the corresponding optically active alcohols (80–99% yield). 相似文献
155.
T. Ikeshoji G. Torchet K. Koga 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):211-214
Surface tension and pressure (stress) tensors of
Lennard-Jones clusters, in the size range 200 ~ 2700
atoms/cluster, formed from evaporating liquid droplets were
calculated in a Molecular Dynamics simulation. Icosahedral
clusters have a much larger surface tension than decahedral,
fcc, and hcp ones, meanwhile asymmetric icosahedral clusters
have a lower surface tension. Fcc and hcp clusters have a very
small surface tension. Decahedral clusters have a surface
tension closer to that of fcc and hcp ones than to that of
icosahedral ones, though both icosahedral and decahedral
structures have five fold symmetry axis. Binary component
clusters have a higher surface tension than single component
ones. 相似文献
156.
Nishimura T Sawano T Ou K Hayashi T 《Chemical communications (Cambridge, England)》2011,47(36):10142-10144
Catalytic addition of silylacetylenes to α,β-unsaturated ketones proceeded in the presence of a cobalt complex coordinated with a bisphosphine ligand to give high yields of β-alkynylketones. 相似文献
157.
Seshamaheswaramma K Reddy GU Reddy AV Lakshmi Reddy S Frost RL Endo T 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,81(1):308-312
The mineral sphalerite (Zn,Fe)S has been characterized by a combination of X-ray diffraction, EPR and NIR spectroscopy. The optical absorption spectrum of mineral sphalerite is due to an iron impurity only, which is in a distorted octahedral environment. The g=2.2 is attributed to iron and g and A value observed in the spectrum 1.999 and 6.0 mT are assigned to Mn(II) impurity in the mineral. These results indicate that iron and Mn(II) impurity have entered the lattice by substitution. The EPR results confirm the presence of manganese in a distorted octahedral environment. It is evident from the chemical analysis that iron is present in higher concentrations. NIR results are due to the presence of water and sulphide fundamentals which also support the formula of the mineral. No sulphate in the sphalerite mineral was observed. 相似文献
158.
Reddy SL Maheswaramma KS Reddy RR Reddy AV Nakamura Y Reddy BJ Endo T Frost RL 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(4):1240-1244
A zoisite group of mineral samples from different localities are used in the present study. An EPR study on powdered samples confirms the presence of Mn(II), Fe(III) and Cr(III) in the minerals. NIR studies confirm the presence of these ions in the minerals. 相似文献
159.
160.
Ikeshoji T Otani M Hamada I Okamoto Y 《Physical chemistry chemical physics : PCCP》2011,13(45):20223-20227
The water dissociation reaction and water molecule configuration on a positively charged platinum (111) surface were investigated by means of first principles molecular dynamics under periodic boundary conditions. Water molecules on the Pt surface were mostly in the O-down orientation but some H-down structures were also found. OH(-) ion, generated by removing H from H(2)O in the bulk region, moved to the Pt surface, on which a positive charge is induced, by a Grotthuss-like proton-relay mechanism and adsorbed on it as OH(Pt). Hydrogen atom exchange between OH(Pt) and a near-by water molecule frequently occurred on the Pt surface and had a low activation energy of the same order as room temperature energy. When a positive charge (7 μC cm(-2)) was added to the Pt surface, H(3)O(+) and OH(Pt) were generated from 2H(2)O on the Pt. This may be coupled with an electron transfer to the Pt electrode [2H(2)O → H(3)O(+) + OH(Pt) + e(-)]. The opposite reaction was also observed on the same charged surface during a simulation of duration about 10 ps; it is a reversible redox reaction. When further positive charge (14 μC cm(-2)) was added, the reaction shifted to the right hand side completely. Thus, this one-electron transfer reaction, which is a part of the oxygen electrode reaction in fuel cells and water electrolysis, was confirmed to be a low activation energy process. 相似文献