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Three-dimensional images for electron-impact single ionization of He: complete and comprehensive (e, 2e) benchmark
M Dürr1, C Dimopoulou, B Najjari
1Max-Planck-Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg, Germany.
Physical Review Letters
|August 16, 2006
Summary
Electron-impact ionization of helium reveals unexpected out-of-plane electron emissions. This finding challenges current theoretical models, providing a benchmark for quantum problem descriptions.
Area of Science:
- Atomic and Molecular Physics
- Quantum Mechanics
- Chemical Physics
Background:
- Electron-impact ionization is a fundamental atomic collision process.
- Understanding helium single ionization is crucial for atomic physics.
- Previous theoretical models often focused on coplanar emission.
Purpose of the Study:
- To present comprehensive fully differential cross sections for electron-impact single ionization of helium.
- To investigate electron emission in all three spatial dimensions.
- To challenge and benchmark existing theoretical models.
Main Methods:
- Utilized an advanced reaction microscope.
- Performed experiments at 1 keV and 102 eV electron impact energies.
- Measured fully differential cross sections for electron emission.
Main Results:
- Observed significant and surprising out-of-plane electron emission contributions.
- Identified an interference term in a perturbation expansion as the source.
- Data were compared with ion-impact data to understand the phenomenon.
Conclusions:
- The observed out-of-plane emission challenges theoretical models that accurately predict only coplanar emission.
- The experimental data serve as a critical benchmark for advanced theoretical calculations.
- This study advances the understanding of fundamental three-body quantum problems.