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Abstract Ionization collisions have important consequences in many physical phenomena, and the mechanism that leads to ionization is not universal. Double differential cross sections (DDCSs) are often used to identify ionization mechanisms because they exhibit features that distinguish close collisions from grazing collisions. In the angular DDCS, a sharp peak indicates ionization through a close binary collision, while a broad angular distribution points to a grazing collision. In the DDCS energy spectrum, electrons ejected through a binary encounter collision result in a peak at an energy predicted from momentum conservation. These insights into ionization processes are well-established for plane wave projectiles. However, the recent development of sculpted particle wave packets reopens the question of how ionization occurs for these new particle wave forms. We present theoretical DDCSs for (e, 2e) ionization of atomic hydrogen for electron vortex projectiles. Our results predict that the ionization mechanism for vortex projectiles is similar to that of non-vortex projectiles, but that the projectile’s momentum uncertainty causes noticeable changes to the shape and magnitude of the vortex DDCSs. Specifically, there is a broadening and splitting of the angular DDCS peak for vortex projectiles, and an increase in the cross section for high energy ejected electrons.
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A distorted-wave approach to the elastic scattering of twisted electrons
Abstract The elastic scattering of spinless vortex electrons on realistic target atoms has been investigated. In particular, expressions are derived in different approximations for the angular distribution of elastically scattered electrons. We develop a distorted wave formalism that includes the effect of the atomic potential on the impinging vortex electron and compare this to a plane-wave Born approximation without such a distortion. Detailed computations have been performed for elastic scattering of vortex electrons on helium, neon, and argon targets by varying the energy, topological charge, and opening angle. Our results show that the overall magnitude of the angular distribution of scattered electrons increases when the distortion by the bound-state electrons is taken into account. We also show that under certain conditions, such as high-Z targets or projectiles with low values of topological charge, significant differences in electron angular distribution shape and magnitude are observed between the distorted-wave and plane-wave Born models. Thus, the plane-wave Born approximation must be used with caution when describing vortex electron collisions.
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- Award ID(s):
- 2207209
- PAR ID:
- 10585918
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Journal of Physics B: Atomic, Molecular and Optical Physics
- ISSN:
- 0953-4075
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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