Few-electron corrections of statistical exchange potential in low-energy electron scattering

In order to allow for the relative increase of self-interaction in few-electron systems, a reduction factor is introduced into the statistical free-electron exchange potential. This net-exchange potential has been used in the calculation of elastic electron scattering by rare-gas atoms in the low-energy region from 0 to 10 eV. Whereas former attempts to treat these phenomena as simple potential scattering have failed, in this work at least a crude qualitative agreement with experimental data has been achieved in most cases.     

Massenspektrometrische Untersuchung von Amiden: III—Intramolekulare Nucleophile Substitution bei der Methyl-Abspaltung aus Crotonsaurepiperidid und Vinylogen Derivaten

The methyl cleavage from piperidides of type CH₃(CH?CH)_nCONC₅H₁₀ with n = 1 to 3 does not proceed via ring contraction as shown earlier with n = 0. The fragmentation can be formulated with the concept of neighbouring group participation of the amide function which leads to a cyclic transition state. Investigations with a ²H-labelled compound in the case of n = 1 as well as energy measurements (AP, IP, E_k) agree with this assumption.     

Theory-enforced Re-investigation of the Origin of the Large Metal–Carbon Bond Strength in PdCH2I+ and its reactions with unsaturated hydrocarbons

State-of-the-art ab initio studies demonstrate that the reaction Pd⁺ + CH₃I → PdCH₂I⁺ + H^. is endothermic by ca. 20 kcal/mol, which translates into a bond dissociation energy (BDE) of ca. 83 kcal/mol for the Pd⁺? CH₂I bond. This figure is in agreement with an experimental bracket of 68 kcal/mol < BDE(Pd⁺? CH₂I) < 92 kcal/mol. Based on these findings, the previously studied Pd⁺/CH₃I system was re-investigated, and double-resonance experiments demonstrate that the formation of PdCH₂I⁺ occurs stepwise via PdCH as a reactive intermediate. Further, ion/molecule reactions of PdCH₂I⁺ with unsaturated hydrocarbons are studied, which reveal the formation of carbon–carbon bonds in the gas phase.     

Periodic,multiplicative number-theoretical functions

D. Leitmann andD. Wolke [3] proved that multiplicative functions, which are restrictions of continuous, periodic functionsF: with irrational period, are constant equal to 0 or 1. In this note a simpler proof for this result is given.     

On the theory of heat transfer from a wire in an electric field

Summary If an electric field is applied between a horizontal heated wire and a concentric cylinder filled with gas, then, as first shown experimentally by Senftleben and Braun, the heat transfer from the wire is increased due to the electrostrictive forces which modify the circulation current of free convection. In analogy with the characteristic number of Grashof a new electrical characteristic number is introduced which makes it possible to represent the measurements of Senftleben and Braun in a single graph. From this graph the extra heat loss caused by an electric field of cylindrical symmetry around any horizontal wire in an arbitrary gas can be read off directly.     

Finite size effects on structure and magnetism in mass-selected CoPt nanoparticles

In this paper, the one-way absorption property in one-dimensional dielectric/metal photonic crystal structure with a dielectric defect layer is studied. The effects of incident angle and state of polarization on one-way absorption behaviour of the anti-resonant (AR) mode are investigated. The normally incident wave from left to right propagation is totally allowed to penetrate to the structure but right to left propagation totally reflected at the same wavelength. It is found that, with increasing of the incident angle, the AR mode shifts to the lower wavelengths and its intensity decreases. Simultaneously, another AR mode with reversed one-way property appears at higher wavelength. The one-way behaviour on absorption is observed at the both states of polarizations but is localized on different wavelengths. Those effects, are suggesting that the proposed structure can be used as a direction sense polarization splitter or reflector/antireflector device.