TY  - JOUR
AU  - Kühn, Steffen
AU  - Shah, Chintan
AU  - López-Urrutia, José R. Crespo
AU  - Fujii, Keisuke
AU  - Steinbrügge, René
AU  - Stierhof, Jakob
AU  - Togawa, Moto
AU  - Harman, Zoltán
AU  - Oreshkina, Natalia S.
AU  - Cheung, Charles
AU  - Kozlov, Mikhail G.
AU  - Porsev, Sergey G.
AU  - Safronova, Marianna S.
AU  - Berengut, Julian C.
AU  - Rosner, Michael
AU  - Bissinger, Matthias
AU  - Ballhausen, Ralf
AU  - Hell, Natalie
AU  - Park, SungNam
AU  - Chung, Moses
AU  - Hoesch, Moritz
AU  - Seltmann, Jörn
AU  - Surzhykov, Andrey S.
AU  - Yerokhin, Vladimir A.
AU  - Wilms, Jörn
AU  - Porter, F. Scott
AU  - Stöhlker, Thomas
AU  - Keitel, Christoph H.
AU  - Pfeifer, Thomas
AU  - Brown, Gregory V.
AU  - Leutenegger, Maurice A.
AU  - Bernitt, Sven
TI  - High Resolution Photoexcitation Measurements Exacerbate the Long-Standing Fe XVII Oscillator Strength Problem
JO  - Physical review letters
VL  - 124
IS  - 22
SN  - 1079-7114
CY  - College Park, Md.
PB  - APS
M1  - PUBDB-2020-05089
M1  - arXiv:1911.09707
SP  - 225001 (1-7)
PY  - 2020
N1  - Phys. Rev. Lett. 124, 225001 (2020). Main text (6 pages, 3 figures), Supplmentary Material (8 pages, 4 figure), Published in Physical Review Letters
AB  - 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.
KW  - Plasma and Beam Physics (autogen)
LB  - PUB:(DE-HGF)16
C6  - pmid:32567918
UR  - <Go to ISI:>//WOS:000537197200006
DO  - DOI:10.1103/PhysRevLett.124.225001
UR  - https://bib-pubdb1.desy.de/record/453253
ER  -