http://arxiv.org/abs/2003.05965
We resonantly excite the $K$ series of O$^{5+}$ and O$^{6+}$ 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 O$^{5+}$ reveal strong two-electron-one-photon (TEOP) transitions. We find that for the $1s\,2s\,5p\, ^1P_1$ state, TEOP relaxation is by far stronger than the competing, and usually much faster, allowed Auger and radiative decay paths. This enhanced TEOP decay arises from a strong correlation with the near-degenerate upper state $1s\,2p\,4s\, ^1P_1$ of a $K\alpha$ satellite. 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 various electronic energy degeneracies and level mixings are far more common.
M. Togawa, S. Kühn, C. Shah, et. al.
Mon, 16 Mar 20
45/57
Comments: 8 pages, 6 figures (incl. Supplement Materia) submitted to PRL