Physical Sciences and Mathematics | Open Access Articles

Target Electron Ionization In Li²⁺-L-Li Collisions: A Multi-Electron Perspective, Maciej Dominik Piewanowski, Laszlo Gulyas, Marko W. Horbatsch, Johannes Goullon, Natalia Ferreira, Renate Hubele, Vitor L B D De Jesus, H. Lindenblatt, Katharina R. Schneider, Michael Schulz, Michael Schuricke, Z. Song, Shaofeng Zhang, Daniel Fischer, Tom Kirchner

Physics Faculty Research & Creative Works

Target electron removal in Li²⁺-Li collisions at 2290 keV/amu is studied experimentally and theoretically for ground and excited lithium target configurations. It is shown that in outer-shell ionization a single-electron process plays the dominant part. However, the K-shell ionization results are more difficult to interpret. According to our calculations, the process is shown to be strongly single-particle like. On one hand, a high resemblance between theoretical single-particle ionization and exclusive inner-shell ionization is demonstrated, and contributions from multi-electron processes are found to be weak. On the other hand, it is indicated by the discrepancy between experimental and single-particle …

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Postcollision Effects In Target Ionization By Ion Impact At Large Momentum Transfer, Michael Schulz, B. Najjari, Alexander B. Voitkiv, Katharina R. Schneider, Xincheng Wang, Aaron C. Laforge, Renate Hubele, Johannes Goullon, Natalia Ferreira, Aditya H. Kelkar, Manfred Grieser, Robert Moshammer, Joachim Hermann Ullrich, Daniel Fischer

Physics Faculty Research & Creative Works

We have measured and calculated fully differential cross sections for target ionization in 16-MeV O⁷⁺+He and 24-MeV O⁸⁺+Li collisions. As in previous studies, in the case of the He target we observe a pronounced forward shift in the angular distribution of the electrons relative to the direction of the momentum transfer q at small q (q < 1 a.u.). An unexpected result is that we also find a strong forward shift at large q (q > 2 a.u.), while at intermediate q this shift becomes very weak or even turns into a backward shift. For the Li target, in contrast, the forward shift monotonically increases with increasing q. These observations are qualitatively reproduced by our calculations. …

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Polarization And Interference Effects In Ionization Of Li By Ion Impact, Renate Hubele, Aaron C. Laforge, Michael Schulz, Johannes Goullon, Xincheng Wang, B. Najjari, Natalia Ferreira, Manfred Grieser, Vitor L B D De Jesus, Robert Moshammer, Katharina R. Schneider, Alexander B. Voitkiv, Daniel Fischer

Physics Faculty Research & Creative Works

We present initial-state selective fully differential cross sections for ionization of lithium by 24 MeV O8⁺ impact. The data for ionization from the 2s and 2p states look qualitatively different from each other and from 1s ionization of He. For ionization from the 2p state, to which in our study the m_L=-1 substate predominantly contributes, we observe orientational dichroism and for 2s ionization pronounced interference which we trace back to the nodal structure of the initial-state wave function.

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Ion-Lithium Collision Dynamics Studied With A Laser-Cooled In-Ring Target, Daniel Fischer, Dominik Globig, Johannes Goullon, Manfred Grieser, Renate Hubele, Vitor L B D De Jesus, Aditya H. Kelkar, Aaron C. Laforge, H. Lindenblatt, Deepankar S. Misra, B. Najjari, Katharina R. Schneider, Michael Schulz, Martin Sell, Xincheng Wang

Physics Faculty Research & Creative Works

We present a novel experimental tool allowing for kinematically complete studies of break-up processes of laser-cooled atoms. This apparatus, the 'MOTReMi,' is a combination of a magneto-optical trap (MOT) and a reaction microscope (ReMi). Operated in an ion-storage ring, the new setup enables us to study the dynamics in swift ion-atom collisions on an unprecedented level of precision and detail. In the inaugural experiment on collisions with 1.5MeV/amu O8 ⁺-Li the pure ionization of the valence electron as well as the ionization-excitation of the lithium target was investigated.

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Positronium Formation In Positron-Li And Positron-Na Collisions At Low Energies, Anh-Thu Le, M. W. J. Bromley, C. D. Lin

Physics Faculty Research & Creative Works

We present the positronium formation cross sections for a positron colliding with lithium and sodium for the collision energies from 0.01 eV up to 20 eV by the hyperspherical close-coupling method. For Li, our results agree with the experimental data and with other calculations. Our results for Na remain in agreement with previous close-coupling calculations, but do not support the latest experimental data for Na below 1 eV. To validate our model potentials and method in the low-energy regime, the binding energies of positronic lithium and positronic sodium as well as the s-wave scattering lengths for positronium scattering from Li⁺ …

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Physics Faculty Research & Creative Works

Positronium Formation In Positron-Li And Positron-Na Collisions At Low Energies, Anh-Thu Le, M. W. J. Bromley, C. D. Lin

Physics Faculty Research & Creative Works