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991.
At least three different types of oxygen atoms may be present in the surface region of Pd(111) which may be distinguished by their thermal, chemical, structural and electronic properties. Exposure to O2 at low temperatures causes the formation of 2 × 2 and structures from chemisorbed oxygen, the latter being probably stabilized by small amounts of Hab or COab on the surface. The initial sticking coefficient was estimated to be about s0 ≈ 0.3, the adsorption energy ~55 kcal/mole. The photoelectron spectrum exhibits an additional maximum at 5 eV below EF. During thermal desorption dissolution of oxygen in the bulk strongly competes; on the other hand absorbed oxygen may diffuse to the surface giving rise to high temperature peaks in the flash desorption spectra. High temperature (~1000 K) treatment of the sample with O2 causes the formation of a more tightly bound surface species also characterized by a 2 × 2 LEED pattern which is chemically rather stable and which is considered to be a transition state to PdO. The latter compound is only formed by interaction with NO at about 1000 K via the reaction which offers a rather high “virtual” oxygen pressure. This reaction leads to drastic changes of the photoelectron spectrum and is also identified within the LEED pattern. 相似文献
992.
Linda R. Brown Robert A. Toth Alan G. Robiette Jens-Erik Lolck Robert H. Hunt James W. Brault 《Journal of Molecular Spectroscopy》1982,93(2):317-350
Line assignments, positions, strengths, and experimentally determined upper states are reported for the ν1 and ν2 + ν4 infrared bands of 12CH4. The bands have been analyzed using infrared spectra recorded with different optical densities and temperatures at 0.02- and 0.01-cm?1 resolution using a four-passed grating spectrometer at Florida State University and a Fourier transform spectrometer at Kitt Peak National Observatory. Both ν1 and ν2 + ν4 lines are assigned through J′ = 14. For J′ ≥ 10, the upper state of the vibrationally infrared inactive ν1 band interacts strongly with ν2 + ν4 and is observed in the infrared spectrum with line strengths on the order of 10?3 cm?2 atm?1. The upper-state energies and transition intensities are calculated from the molecular constants and transition moment matrix elements obtained through a simultaneous analysis of ν1, ν3, ν2 + ν4, 2ν4, and 2ν2. 相似文献
993.
K.H. Althoff H. Beckschulze R. Conrad J. DeWire H. Herr E. Hilger V. Kadansky O. Kaul D. Menze W. Meyer 《Nuclear Physics B》1975,96(3):497-508
At the Bonn 2.5 GeV electron synchrotron the first measurements of the target asymmetry for the reaction γ + n ↑ → π? + p have been performed. The negative pions were detected in a magnetic spectrometer at a constant pion c.m. angle of 40° and photon energies between 0.45 GeV and 2.0 GeV. Deuterated butanol was used as target material. The polarization of the deuterons was about 16%. The results show a significant difference from the previously measured π+ asymmetry. 相似文献
994.
Clive E. Barnes John M. Brown Alan D. Fackerell Trevor J. Sears 《Journal of Molecular Spectroscopy》1982,92(2):485-496
Lines in the ν3 (“antisymmetric” stretch) fundamental of the NCO radical in the state were studied by CO laser magnetic resonance. The observations were assigned to P and R lines in the vibration-rotation band and lead to a precise determination of the vibrational interval and the anharmonic correction to the rotational constant: ν3 = 1920.60645(19) cm?1, α3 = 0.003338(21) cm?1. A single transition in the hot band (011)-(010), was detected. This observation is used to determine the origin of the hot band as 1907.11892(20) cm?1, i.e., the anharmonicity parameter x23 = ?13.48753(28) cm?1. 相似文献
995.
996.
Alan Jeffrey 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1964,15(3):217-227
Zusammenfassung In der vorliegenden Arbeit wird das Verhalten physikalischer Grössen im Bereich schneller und langsamer magnetohydrodynamischer einfacher Wellen untersucht. Zuerst wird bewiesen, dass zwischen schnellen und langsamen Wellen kein Übergang möglich ist. Dann wird für die betreffenden Fälle eine Bestimmung der verallgemeinerten Riemannschen Invarianten durchgeführt und das numerische Verhalten einer in diesem Zusammenhang wichtigen Differentialgleichung studiert. 相似文献
997.
Alan Jeffrey 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1963,14(4):301-314
Zusammenfassung Die vorliegende Abhandlung untersucht die Fortpflanzung kleiner Unstetigkeiten in Systemen von nichtlinearen hyperbolischen Differentialgleichungen. Ein Ausdruck wird abgeleitet, der die Änderung in der Intensität der Unstetigkeit angibt, wenn diese sich entlang eines Strahls des hyperbolischen Gleichungssystems fortbewegt. Schliesslich wird als Beispiel mit Hilfe des angegebenen Verfahrens die Fortpflanzung von Schallwellen behandelt. 相似文献
998.
‘Unexpected’ second-order effects encountered in proton-coupled 13C NMR spectra where relative proton shifts are large compared to proton-proton coupling constants are illustrated. The observed phenomenon is explained, with reference to the ABX spin system as a model, as being due to the near equality of the relative proton shift, in frequency units, to the difference between one-bond and long-range 13CH couplings. The effect may be removed by a change in operating field strength or addition of a shift reagent. 相似文献
999.
1000.