Proceedings

EPJ D Highlight - Bound and virtual states in low-energy electron and positron scattering

Bound and virtual states in electron-noble gas scattering

New mathematical approach confirms that low-energy charged particles can briefly bind to atoms or molecules

So far, it has remained an open question whether moving charged particles can briefly form bound states with neutral atoms and molecules. In previous experiments, researchers observed enhanced positron annihilation at energies corresponding to specific vibrational modes in neutral molecules, which they interpreted as evidence that the positrons were briefly bound. Until now, however, this interpretation has not yet been corroborated through other scattering observables.

Through new research published in EPJ D, Kamil Fedus and Grzegorz Karwasz at Nicolaus Copernicus University, Poland, present a new method for estimating the energies of both bound and virtual states of low-energy charged particles from elastic scattering cross-sections. Their approach confirms previous theoretical predictions about the formation of bound and virtual states during the scattering of these particles—helping physicists better understand how the scattering process unfolds.

When in a bound state, a charged particle like an electron or positron becomes trapped within an atom or molecule. In a virtual state, the particle is almost trapped, but scatters away almost immediately—never forming a true bound state. If either of these states forms when charged particles interact with neutral atoms or molecules, it can strongly affect the scattering process at low energies.

To explore this possibility, Fedus and Karwasz applied a combination of mathematical techniques that utilise the analytic properties of the attractive polarisation interaction between incoming electrons and positrons, and the neutral atoms and molecules from which they scatter. They then validated their method by comparing their calculations with established theoretical and experimental data.

Fedus and Karwasz applied their approach to positron scattering from large hydrocarbon molecules, and to electron scattering from heavy noble gas atoms. In each case, their results demonstrated that bound and virtual states do form and confirmed the energies of these states from previous studies. Additionally, they provided the first estimate of the binding energy between an electron and an atom of oganesson: the heaviest and most recently discovered element on the periodic table.

This was our first experience of publishing with EPJ Web of Conferences. We contacted the publisher in the middle of September, just one month prior to the Conference, but everything went through smoothly. We have had published MNPS Proceedings with different publishers in the past, and would like to tell that the EPJ Web of Conferences team was probably the best, very quick, helpful and interactive. Typically, we were getting responses from EPJ Web of Conferences team within less than an hour and have had help at every production stage.
We are very thankful to Solange Guenot, Web of Conferences Publishing Editor, and Isabelle Houlbert, Web of Conferences Production Editor, for their support. These ladies are top-level professionals, who made a great contribution to the success of this issue. We are fully satisfied with the publication of the Conference Proceedings and are looking forward to further cooperation. The publication was very fast, easy and of high quality. My colleagues and I strongly recommend EPJ Web of Conferences to anyone, who is interested in quick high-quality publication of conference proceedings.

On behalf of the Organizing and Program Committees and Editorial Team of MNPS-2019, Dr. Alexey B. Nadykto, Moscow State Technological University “STANKIN”, Moscow, Russia. EPJ Web of Conferences vol. 224 (2019)

ISSN: 2100-014X (Electronic Edition)

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