Observation of strong two-electron-one-photon transitions in few-electron ions

M. Togawa, S. Kühn, Chintan Shah, Pedro Amaro, René Steinbrügge, J. Stierhof, N. Hell, Marieke Rosner, K. Fujii, M. Bissinger, R. Ballhausen, M. Hoesch, J. Seltmann, Sungnam Park, Filipe Grilo, F. S. Porter, José Paulo Santos, M. Chung, T. Stöhlker, J. WilmsThomas Pfeifer, G. V. Brown, M. A. Leutenegger, Sven Bernitt, José R. Crespo López-Urrutia

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We resonantly excite the K series of O5+ and O6+ up to principal quantum number n=11 with monochromatic x rays, producing K-shell holes, and observe their relaxation by soft-x-ray emission. Some photoabsorption resonances of O5+ reveal strong two-electron-one-photon (TEOP) transitions. We find that for the [(1s2s)15p3/2]3/2;1/2 states, TEOP relaxation is by far stronger than the radiative decay and competes with the usually much faster Auger decay path. This enhanced TEOP decay arises from a strong correlation with the near-degenerate upper states [(1s2p3/2)14s]3/2;1/2 of a Li-like satellite blend of the He-like Kα transition. Even in three-electron systems, TEOP transitions can play a dominant role, and the present results should guide further research on the ubiquitous and abundant many-electron ions where electronic energy degeneracies are far more common and configuration mixing is stronger.

Original languageEnglish
Article number053109
JournalPhysical Review A
Issue number5
Publication statusPublished - 25 Nov 2020


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