%0 Journal Article
%A Kühn, Steffen
%A Shah, Chintan
%A López-Urrutia, José R. Crespo
%A Fujii, Keisuke
%A Steinbrügge, René
%A Stierhof, Jakob
%A Togawa, Moto
%A Harman, Zoltán
%A Oreshkina, Natalia S.
%A Cheung, Charles
%A Kozlov, Mikhail G.
%A Porsev, Sergey G.
%A Safronova, Marianna S.
%A Berengut, Julian C.
%A Rosner, Michael
%A Bissinger, Matthias
%A Ballhausen, Ralf
%A Hell, Natalie
%A Park, SungNam
%A Chung, Moses
%A Hoesch, Moritz
%A Seltmann, Jörn
%A Surzhykov, Andrey S.
%A Yerokhin, Vladimir A.
%A Wilms, Jörn
%A Porter, F. Scott
%A Stöhlker, Thomas
%A Keitel, Christoph H.
%A Pfeifer, Thomas
%A Brown, Gregory V.
%A Leutenegger, Maurice A.
%A Bernitt, Sven
%T High Resolution Photoexcitation Measurements Exacerbate the Long-Standing Fe XVII Oscillator Strength Problem
%J Physical review letters
%V 124
%N 22
%@ 1079-7114
%C College Park, Md.
%I APS
%M PUBDB-2020-05089
%M arXiv:1911.09707
%P 225001 (1-7)
%D 2020
%Z Phys. Rev. Lett. 124, 225001 (2020). Main text (6 pages, 3 figures), Supplmentary Material (8 pages, 4 figure), Published in Physical Review Letters
%X For more than 40 years, most astrophysical observations and laboratory studies of two key soft x-ray diagnostic 2p−3d transitions, 3C and 3D, in Fe XVII ions found oscillator strength ratios f(3C)/f(3D) disagreeing with theory, but uncertainties had precluded definitive statements on this much studied conundrum. Here, we resonantly excite these lines using synchrotron radiation at PETRA III, and reach, at a millionfold lower photon intensities, a 10 times higher spectral resolution, and 3 times smaller uncertainty than earlier work. Our final result of f(3C)/f(3D)=3.09(8)(6) supports many of the earlier clean astrophysical and laboratory observations, while departing by five sigmas from our own newest large-scale ab initio calculations, and excluding all proposed explanations, including those invoking nonlinear effects and population transfers.
%K Plasma and Beam Physics (autogen)
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:32567918
%U <Go to ISI:>//WOS:000537197200006
%R 10.1103/PhysRevLett.124.225001
%U https://bib-pubdb1.desy.de/record/453253