Zur Spinpolarisation langsamer Elektronen nach der Streuung an Molekülen

Cross sections and spin polarization of low-energy electrons scattered by I₂ and C₂H₅I molecules were measured in the energy range from 200 to 600 eV and angular range from 30 to 150°. At the same time, several authors made calculations of cross sections and polarizations based on the following assumptions: The molecule consists of free atoms which are independent of each other (the influence of binding is negligible) and scattering of an electron does not occur more than once within the molecule. The agreement between theory and experiment in a wide angular range justifies these assumptions for the present problems. Polarization values lower than the theoretical ones were measured only at scattering angles where the theory predicts very narrow and high values of the spin polarization. Qualitative arguments show that intramolecular scattering very likely is responsible for the deviations found between theoretical and experimental polarization peaks. By means of the polarization of the scattered intensity one can easily decide how much of the scattered intensity comes from one part of the molecule and how much comes from the other part.     

Streuung von Laserphotonen an schnellen Elektronen

The high laser intensity allows colliding-beam Compton scattering experiments of high-energy electrons with the photons of the red ruby laser light by which the latter are transformed intoγ-radiation photons. Detailed calculations are given in this paper for the “average” polarization over the scattered beam and for the energy spectrum of theγ-rays.     

Elastische Streuung langsamer Elektronen an einem Bi-Atomstrahl

The angular distribution of electrons elastically scattered by bismuth atoms has been investigated in the angular range from 30 to 155° and with electron energies between 5 and 1200 eV. Theoretical data, which are available for energies above 100 eV, are in good agreement with experiment.     

Spinpolarisation langsamer Elektronen durch elastische Streuung an Edelgasatomstrahlen

Zeitschrift für Physik A Hadrons and nuclei - The angular dependence of spin polarisationP(θ) of electrons elastically scattered by noble gas atomic beams is measured in a...     

Streuung spinpolarisierter Elektronen an Au(110)

Using the the spin modulated polarized electron gun based on photoemission from positive affinity GaAs the intensityI(E, , ) and asymmetry (E, , ) are measured in LEED from Au(110). The asymmetry is compared with the polarizationS(E, , ) which N. Müller obtained with a Mott detector after scattering an unpolarized electron beam from the same crystal. There is excellent agreement for the (00) beams, if the scattering plane is a mirror symmetry plane of the crystal (=0°, =90°). From the differences for the (00) and (11) beams at =35° and the (01/2) beam at =90° conditions for possible models for the reconstructed Au(110)–(1×2) surface may be derived.

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Die vorliegende Arbeit ist ein Auszug aus [1]

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Neue Addresse ab 1. Oktober 1980: B. Reihl, IBM Thomas J. Watson Research Center, Yorktown Heights, NY 10598, USA     

Elastische und unelastische Streuung von Elektronen an Gasen

The theoretical differential cross section for the elastic scattering and for the excitation of optical transitions in helium by electron impact has been refined in Born approximation by use of the two parameter Eckart eigenfunction for the ground state and for the excited states. The angular distributions of 25 kev electrons scattered elastically and inelastically by helium were measured in the angular range 2·3·10^?4≦?≦4·10^?2. The intensity distribution of the elastically scattered electrons is in accordance with the theoretical curve for?>7·10^?3 and is disturbed at smaller angles by the primary beam. Normalization of the experimental values to the theoretical elastic differential cross section leads to agreement between the experimental differential cross section for the excitation of the 2¹ P and 3¹ P state and the scattering formulae given in this paper. There are small systematic deviations (<20%) for the 2¹ P differential cross section in the angular range 3·10^?3<?<1·10^?2 only. The oscillator strength of these two transitions has been determined from the scattering measurements:f ₂₁=0·312±0·04 andf ₃₁=0·0898±0·006.     

Der Beugungseffekt bei der elastischen Streuung von Ionenstrahlen an Atomen

For the elastic scattering of ion beams at atoms the diffraction of the matter wave at the atom can be observed in the region of small scattering angles and high energies. The diffraction causes undulations in the differential scattering cross section. In this paper a general solution of the diffraction effect is given. The solution holds for the Yukawa type screened Coulomb potential which is well suited for the small angle scattering of-ions at atoms and which contains two parameters. The computations have been made using the partial wave method and the Jeffreys-Born-approximation for the scattering phase shifts. The solution is presented in a form in which the amplitudes and characteristic constants of the first four undulation maxima and minima are given in dependence of a product which contains one of the potential parameters. The characteristic constants are correlated in a characteristic equation with the second potential parameter and the positions of the diffraction extrema. The conditions for the appearance of the diffraction effect are discussed.     

Zur Streuung langwelliger Magnonen an Gitterfehlern

The scattering of ferromagnetic magnons by point defects is calculated within the framework of a phenomenological theory. This theory essentially takes account of the magnetic dipole interaction, and the magnetoelastic interaction, which are usually neglected. The scattering is due to an effective magnetic field, which is produced by the longrange strains of the lattice. For small wavenumbers this effective field is more important than the local disturbance of the exchange coupling in the vicinity of the defect, which hitherto has been considered almost exclusively, within the Heisenberg model. Due to the magnetic dipole interaction, the scattered wave and the differential cross section depend on the angle in a rather complicated manner: For each direction of scattering there are up to three groups of scattered waves, running away from the defect with different velocities. The differences between the classical and the quantum mechanical calculation are worked out.     

Streuung von Elektronen an Quecksilberatomen im Energiebereich 200 bis 4000 eV

Angular distributions of the single scattering of 200 to 4000 eV electrons are measured over a wide angular range and compared with recent calculations, the accuracy of which is theoretically hard to access. The scattering intensity being continuously recorded, even fine details of the angular distributions were obtained accurately. The calculations ofHolzwarth andMeister turned out to be correct even in these details.     

Messung der Spinpolarisation langsamer Elektronen nach elastischer Streuung an festen Hg-Targets

SpinpolarizationP(Θ) of slow electrons elastically scattered by a solid Hg-target has been studied in a double-scattering experiment for electron energies between 300 eV and 900 eV. For the same energy range the angular dependence of the scattered intensity has been measured. Maximum degree of polarization found isP=?0.23±0.04 (E=900 eV,Θ=105°).     

Differentielle Wirkungsquerschnitte für die elastische Streuung niederenergetischer Elektronen an Natrium

The elastic differential cross section of electrons scattered by sodium has been measured over the angular range from 25 ° to 150 ° and with electron energies between 0.5 and 20 eV. The agreement of the results with recent theoretical values is good.     

Differentielle Wirkungsquerschnitte für die elastische Streuung niederenergetischer Elektronen an Kalium

The 2.41 min ground state decay of¹⁰⁸Ag has been studied with a Ge(Li) detector. Twelve transitions are observed of which seven have not been reported previously. Five of the new transitions are placed in the level scheme which includes the second 2⁺, 930.4 keV level and a new level at 1539.4 keV in¹⁰⁸Pd.     

über die Streuung relativistischer Elektronen im Coulombfeld

An approximative method for summing the partial wave series for the scattering amplitude of the relativistic scattering of electrons by an atomic nucleus is investigated in the simplest case of a point charge nucleus for electron energies not less 10 MeV. In the course of the computationΒ=1 is assumed (Β=v/c,v andc denote the velocity of the electron and of light, respectively). The Sommerfeld-Watson-transformation is the starting point. The method consists in setting up an asymptotic expansion in 1/sin² (θ/2) (θ is the scattering angle) of the amount coming from the Regge-poles. Two further amounts, the dependence of which on the scattering angle especially for easy nuclei is little, are computed numerically without simplification, which should be possible. The method is developed from a special way of summing the partial wave series for the non-relativistic Rutherford scattering, which may be done analytically.Mott's scattering formula is verified and finally the applicability of the method is examined for summing the relativistic partial wave series with the exact S-Matrix. The results are as exact as the expension of the cross section to order (Z/137)⁵ (Z is the nuclear charge). The method should in principle be applicable for an extended nucleus, but in this case there remain still several problems.