Orientation dependence of the differential cross section in elastic electron scattering from<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">CH</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>I molecules

Volkmer, M.; Meier, Ch.; Lieschke, J.; Mihill, A. G.; Fink, Manfred; Böwering, N.

doi:10.1103/physreva.53.1457

Cited by 16 publications

(10 citation statements)

References 40 publications

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“…Molecular orientational interference contributions 32 +, M-, ~fA and 3~ o as a fraction of the elastic electron scattering cross section for unoriented molecules obtained as a function of momentum transfer at Uo=4 kV for the molecular beam with T~o,~25 K. Data points: Experimental values; Full drawn lines: theoretical results at Uo=4 kV; Dashed lines: theoretical results for the hexapote voltages U0; --3 kV, -.-3.4 kV, ---5 kV, ---7 kV, -..-10 kV; Insets: polar plots of the axis orientational distribution ensemble at Uo = 7 kV. Both experimental and theoretical findings resemble the previous results obtained for CH3I molecules under similar expansion conditions[8], although the difference M+-)~f-was not zero in the case of CH3I[11]. Both experimental and theoretical findings resemble the previous results obtained for CH3I molecules under similar expansion conditions[8], although the difference M+-)~f-was not zero in the case of CH3I[11].…”

supporting

confidence: 76%

“…The elastic electron differential cross section da/d(2 for oriented (or aligned) molecules in a specific rotational quantum state i = [J, K, M> contains an additional interference contribution to the usual cross section for unoriented molecules and is generally given by [4,8,11]: da da (1) In our particular scattering geometry the electric Stark field is parallel or antiparallel to the electron beam. The additional interference contribution MjKM arising for oriented states depends then only on the polar electron scattering angle 0 and is independent of the azimuthal angle Z~.…”

Section: General Considerationsmentioning

confidence: 99%

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Electron diffraction from oriented molecules:e—CH3Cl

Böwering

Volkmer

Meier

et al. 1994

Z Phys D - Atoms, Molecules and Clusters

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The additional molecular interference contributions to the differential elastic electron scattering cross sections for spatially oriented and partially state-selected CH3C1 molecules have been measured at an incident energy of 1 keV. Using the electrostatic hexapole technique, the molecules were oriented with their axes preferentially parallel or antiparallel to the electron beam. Deviations from the diffraction pattern of unoriented molecules of up to 4% were observed as a function of momentum transfer. A change of the orientational distribution in the state ensemble gave rise to a significantly altered interference pattern with alignment contributions dominating in both cases. For comparison with the data the fractional population of the various states present in the molecular beam was calculated and the independent atom model was applied to obtain the scattering pattern using the formalism of Kohl and Shipsey.

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supporting

confidence: 76%

Section: General Considerationsmentioning

confidence: 99%

Electron diffraction from oriented molecules:e—CH3Cl

Böwering

Volkmer

Meier

et al. 1994

Z Phys D - Atoms, Molecules and Clusters

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“…For a continuous molecular beam with a relatively high rotational temperature T rot , many rotational states are usually present in the focus region, and their contributions have to be weighted accordingly. By combining such a molecular beam apparatus with an electron-scattering unit, the first measurements of differential cross-sections for orientated molecules were obtained in 1992 (Volkmer et al . 1992).…”

Section: Electron Scattering Interactions With Orientated Moleculesmentioning

confidence: 99%

“…In this way, the additional molecular-interference termM (ϑ, χ) for the focused state ensemble can be determined as a fraction of the differential cross-section σ unor = (dσ/ dΩ) unor from measurements of the scattering intensity for orientated, I or , and Figure 13. Measured normalized molecular orientational interference contributions for CH3I (Volkmer et al . 1996) as a function of momentum transfer, obtained at U0 = 7 kV and at 1 keV scattering energy: results for parallel and antiparallel orientation, as well as pure alignment and orientation parts.…”

Section: Electron Scattering Interactions With Orientated Moleculesmentioning

confidence: 99%

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Interactions of polarized electrons and polarized photons with atoms and molecules

Kleinpoppen

Becker

1999

Philosophical Transactions of the Royal Society of London. Seri

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In this paper, we initially list 23 subfields of the research topics associated with the title of this paper. Then we present a detailed theoretical description of polarizedelectron interactions with atoms and molecules. Spin effects based on Coulombdirect, Coulomb-exchange and spin-orbit interactions in light and heavy atoms are described, and experimental data are presented as tests for relevant theoretical approximations.Electron-scattering interactions with orientated molecules such as CH 3 I and CH 3 Cl show interesting alignment and orientation effects, which are new types of test quantities for the theory of such electron-scattering processes with molecules.Numerous multielectron effects determine photoionization of atoms in general. Spin, and spin-orbit interaction effects particularly, can be studied by photoelectron spin experiments and by applying polarized atoms in the photoionization process. The former type of experiment has been used very successfully in the photoionization of rare gas atoms, while the latter type of experiment and related theories have been applied particularly for photoionization with partly filled subshells. Out of such photoionization experiments with polarized atoms we selected one involving oxygen atoms {O(1s 2 2s 2 2p 4 ) 3 P 2 + hν} for a more detailed description.While the photoionization process with unpolarized oxygen atoms is characterized by the cross-section, σ, and the angular distribution parameter, β, only; a further parameter, β , is required for photoionization with polarized oxygen atoms. Alternatively, it is possible to describe the photoionization of polarized oxygen atoms by deriving β and β from the ratio of two reduced matrix elements for s and d electrons and their relative phase difference. Keywords: polarized-electron and polarized-atom interactions; scattering of electrons by orientated molecules; photoionization of polarized atoms; 'complete' scattering experiments

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