Preprint Concept Paper Version 1 Preserved in Portico This version is not peer-reviewed

# Mixed-State Ionic Beams: An Effective Tool for Collision Dynamics Investigations

Version 1 : Received: 29 October 2018 / Approved: 30 October 2018 / Online: 30 October 2018 (03:53:32 CET)

A peer-reviewed article of this Preprint also exists.

Benis, E.P.; Madesis, I.; Laoutaris, A.; Nanos, S.; Zouros, T.J.M. Mixed-State Ionic Beams: An Effective Tool for Collision Dynamics Investigations. Atoms 2018, 6, 66. Benis, E.P.; Madesis, I.; Laoutaris, A.; Nanos, S.; Zouros, T.J.M. Mixed-State Ionic Beams: An Effective Tool for Collision Dynamics Investigations. Atoms 2018, 6, 66.

Journal reference: Atoms 2018, 6, 66
DOI: 10.3390/atoms6040066

## Abstract

The use of mixed-state ionic beams in collision dynamics investigations is examined. Using high resolution Auger projectile spectroscopy involving He-like ($1s^2\thinspace^1\!S, 1s2s\thinspace^{3,1}\!S$) mixed-state beams, the spectrum contributions of the $1s2s\thinspace^3\!S$ metastable beam component is effectively separated and clearly identified. This is performed with a technique that exploits two independent spectrum measurements under the same collision conditions, but with ions having quite different metastable fractions, judiciously selected by varying the ion beam charge-stripping conditions. Details of the technique are presented together with characteristic examples. In collisions of 4 MeV B$^{3+}$ with H$_2$ targets, the Auger electron spectrum of the separated $1s2s\thinspace^{3}S$ boron beam component allows for a detailed analysis of the formation of the $1s2s(^3\!S)nl \thinspace^2\!L$ states by direct $nl$ transfer. In addition, the production of hollow $2s2p\thinspace^{1,3}\!P$ doubly- and $2s2p^2\thinspace^2\!D$ triply-excited states, by direct excitation and transfer-excitation processes, respectively, can also be independently studied. In similar mixed-state beam collisions of 15 MeV C$^{4+}$ with H$_2$, He, Ne and Ar targets, the contributions of the $1s^2$, $1s2s\thinspace^{3,1}S$ beam components to the formation of the $2s2p\thinspace^{3,1}\!P$ states by double-excitation, $1s\rightarrow2p$ excitation and transfer-loss processes can be clearly identified, facilitating comparisons with theoretical calculations.

## Keywords

zero-degree Auger projectile spectroscopy; mixed-state beams; metastable states; He-like states; Li-like states; Be-like states; cascade feeding; electron transfer excitation; electron excitation; electron transfer; hollow states; SIMION

## Subject

PHYSICAL SCIENCES, Atomic & Molecular Physics

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