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791.
Electrochemical promotion for the catalytic reduction of NO by CO and of NO by ethylene over a Pt catalyst are reported for
the first time. Both reactions are of importance in the catalytic control of automotive emissions and both exhibit strong
rate enhancement when Na is pumped to the Pt catalyst electrode from a β″ solid electrolyte. Complementary data obtained with
a Pt(111)/Na model system indicate that electrochemically-pumped Na acts by inducing dissociation of chemisorbed NO, which
is the reaction initiating step.
Paper presented at the 1st Euroconference on Solid State Ionics, Zakynthos, Greece, 11 – 18 Sept. 1994. 相似文献
792.
The temperatuure dependence of the vicinal OCH2CH2 coupling constant in the six-membered ring δ-valerolactone suggests the presence of at least two conformers of unequal energy. Analysis of this temperature dependence by the Wood-Fickett-Kirkwood method in six solvents produces free energy differences in the narrow range 0.8–1.4 kcal mol?1, with a mean of 1.0 kcal mol?1 and no apparent dependence on solvent polarity. Thus the two conformers, probably the half-chair and the classic boat, have similar polarities. The analogous four- and five-membered lactones show little or no temperature dependence for their analogous coupling constants, in agreement with the presence of a single conformation for these rings. 相似文献
793.
Inelastic neutron scattering measurements performed on NaNbO3 close to the cubic to tetragonal phase transition show that the 2D fluctuations earlier revealed by X-ray diffuse scattering correspond to an overdamped type dynamics. The sharp decrease in the spectral width observed at T-Tc =10° is interpreted in terms of the increase in correlation lengths and the cross-over between 2D and 3D behaviour of the fluctuations. 相似文献
794.
The adsorption-desorption properties of the gold(111)-chlorine system have been investigated. Thermal desorption experiments following chlorine adsorption at 298 K indicated two desorption processes: the high temperature peak (ΔH = 217 kJmol?1) showed desorption of equal numbers of molecukr and atomic chlorine species, while the lower temperature peak (ΔH = 140 kJmol?1) was due to the desorption of Cl2 only. Chlorine adsorption led to a maximum work function change of +0.5 V and electron-stimulated desorption proceeded with constant cross-section (1.4 × 1018 cm2), until all chlorine had been removed from the surface These observations are consistent with the immediate formation of a surface chloride (AuCl3) during chlorine adsorption on Au(111) at 298 K without the intervention of an initial adsorbed overlayer. 相似文献
795.
Quantum beats and fluorescence decays of the vibrationless S1 state of jet-cooled pyrazine have been studied as a function of magnetic field. Fourier analysis of the modulated portions of these decays has yielded results which are consistent with first- and second-order Zeeman effects occurring in the excited state. An increase in the number of triplets states effetively coupled to the singlet manifold with increasing magnetic field is discussed in terms of Zeeman interactions 相似文献
796.
F. Lambert 《Zeitschrift fur Physik C Particles and Fields》1980,5(2):147-150
The closed form solutions of the Kortewegde Vries (KdV) and modified MKdV equations which are obtainable by inverse scattering or Hirota's method are found to be Pade approximants to the formal series which results from iterating particular solutions of the linearized equation. 相似文献
797.
Joseph M. Lambert 《Numerische Mathematik》1980,35(4):361-368
Summary This paper shows that a computational procedure for approximation of random functions can be accomplished using purely linear programming techniques. This contrasts with previous results which use a twostage approach for the computation, one of which requires linear programming techniques. Computational results are given. 相似文献
798.
Lambert J. Ottendorfer 《Fresenius' Journal of Analytical Chemistry》1979,297(4):254-255
Summary It is emphasized that the teaching of the fundamental topics and basic laws of chemistry should also include guidelines to their practical use and application. The trend to more and more strict specialisation should be compensated by an even deeper consideration of the general aspects.Presented at Euroanalysis III conference, Dublin, August 20–25, 1978 相似文献
799.
S. Aléonard B. Lambert J. Pannetier M.F. Gorius M.Th. Roux 《Journal of solid state chemistry》1985,58(2):226-232
The structure of the phase Cs4?xYb12F40?x(0 ≤ x ≤ 1) has been determined by a single-crystal neutron diffraction study. It has been solved in the space group P63mc and refined to the best R factor of 0.0535 for the formula Cs3.4Yb12F39.4 (324 independent reflections). Three edge-sharing pentagonal bipyramids surrounding three ytterbium atoms form Yb3F16 groups and the structure is described as the superposition, according to the sequence A1A2B1B2A1A2…, of sheets of corner-sharing Yb3F16 groups with a possible transformation of bipyramids into octahedra in the A2 and B2 layers. These sheets are joined together by the axial fluorine atoms of the bipyramids or octahedra. Cesium atoms are located in the tunnels formed by their stacking. It is shown that the Cs4?xYb12F40?x phase (0 ≤ x ≤ 1) is an intermediate step of the Cs4?xYb12F40?x solid solution observed with 0 ≤ x ≤ 2 and corresponds to a superstructure of the high-temperature YbF3 phase. 相似文献
800.
An isotope-dilution spark-source mass-spectrometric procedure has been developed for the accurate determination of sulphur in iron-base alloys. Dissolution in a sealed tube is used to prevent volatilization losses and to effect isotope equilibration. Application of this technique to the re-analysis of existing NBS Standard Reference Materials yields results that are generally in good agreement with the certified values. 相似文献