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1.
Three methods are investigated for obtaining elastic phase shifts in the scattering of electrons from atoms and ions that use a bound-state representation of the scattering wavefunction. Results for singlet p-wave scattering by H and by He+ are compared with previous calculations. 相似文献
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Buckley N Maltby D Burlingame AL Oppenheimer NJ 《The Journal of organic chemistry》1996,61(8):2753-2762
The relative rates for the gas-phase dissociation RX(+) --> R(+) + X degrees of five (4-Y-substituted benzyl)dimethysulfoniums (Y = MeO, Me, H, Cl, and NO(2)) and 24 (4-Y-substituted benzyl)-3'-Z-pyridiniums (complete series for Z = CN, Cl, CONH(2), and H, and 4-methoxy- and 4-nitrobenzyls for Z = F and CH(3)CO) were measured using liquid secondary ion mass spectrometry. The Hammett plot (vs deltaDeltaG degrees or sigma(+)) is linear for the sulfoniums, but plots for the four pyridinium series have a drastic break between the 4-Cl and 4-NO(2) substrates. Br?nsted-like plots for the pyridiniums show a strong leaving group effect only for 4-nitrobenzyls. An analysis of these linear free energy relations with supporting evidence from semiempirical computations suggests that collisionally activated pyridinium substrates dissociate by two pathways, direct dissociation and through an ion-neutral complex intermediate. Comparison of these results with results for the solution reactions of some of these compounds shows that the mechanism is different in the gas and solution phases. Sufficient experimental data are not available to assign a mechanism for dissociation to the sulfonium series, but computational results show characteristics of a direct dissociative mechanism. 相似文献
4.
D. Weidmann G. Wysocki C. Oppenheimer F.K. Tittel 《Applied physics. B, Lasers and optics》2005,80(2):255-260
We report the development of a field-deployable, pulsed quantum cascade laser spectrometer. The instrument is designed to measure the 13C/12C isotopic ratio in the CO2 released from volcanic vents. Specific 12CO2 and 13CO2 absorption lines were selected around 4.3 m, where the P-branch of 12CO2 overlaps the R-branch of 13CO2 of the 0001–0000 vibrational transition. This particular selection makes the instrument insensitive to temperature variations. A dual-channel cell balances the two absorption signals. We provide details of the instrument design and a preliminary demonstration of its performance based on laboratory measurements of 16O12C16O and 16O12C18O. PACS 42.55.Px; 42.62.Fi; 07.88.+y 相似文献
5.
Measurements of synchrotron radiation emitted by 30-MeV runaway electrons in the TEXTOR-94 tokamak show that the runaway population decays after switching on neutral beam injection (NBI). The decay starts only with a significant delay, which decreases with increasing NBI heating power. This delay provides direct evidence of the energy dependence of runaway confinement, which is expected if magnetic modes govern the loss of runaways. Application of the theory by Mynick and Strachan [Phys. Fluids 24, 695 (1981)] yields estimates for the "mode width" (delta) of magnetic perturbations: delta<0.5 cm in Ohmic discharges, increasing to delta = 4.4 cm for 0. 6 MW NBI. 相似文献
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Hermann Oppenheimer 《Monatshefte für Mathematik》1907,18(1):71-107
Ohne Zusammenfassung 相似文献
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Dr. Hermann Oppenheimer 《Monatshefte für Mathematik》1909,20(1):141-170
Ohne Zusammenfassung 相似文献
9.
Adaptive optics systems mitigate the atmospheric turbulence-induced distortion of a propagating light wavefront. The use of adaptive optics entails the design of a feedback controller, which requires the development of a model of the plant to be controlled. In adaptive optics, the plant consists of the atmosphere through which light is traveling. Moreover, a distinct feature of the adaptive optics control application is the presence of random signals in the plant. In optics, Zernike orthonormal polynomials are commonly used as a basis set for the expansion of wavefront phase distortions. Due to the atmospheric turbulence-induced random nature of the underlying physical process, the spatial-temporal correlation functions of the Zernike polynomial phase distortion expansion coefficients must be evaluated if a proper stochastic model of the plant is to be developed and adaptive optics is to be employed. In Part 1 of this paper, these correlation functions are developed using a layered atmospheric model and calculations for the first few low-order Zernike modes are performed. Using these correlation functions, an underlying stochastic linear dynamical system, which is adequate for control design, is synthesized. This system models the plant and, in turn, provides the basis for the employment of advanced model-based control and estimation concepts in an adaptive optics system for an airborne platform application. 相似文献
10.
The behavior of dipole transition matrix elements between adiabatic eigenstates of diatomic molecules is explored in the region of large configuration mixing. It is demonstrated that the matrix element has a lorentzian shape as a function of internuclear distance. The effect of this shape on the spectrum of LiH is investigated. The strong enhancement of the dipole transition moment in the interaction region is suggested as a source for nonthermal population distributions and laser radiation in alkali diatomics and hydrides. 相似文献