학술논문
High Resolution Photoexcitation Measurements Exacerbate the Long-Standing Fe XVII Oscillator Strength Problem
Document Type
Working Paper
Author
Kühn, Steffen; Shah, Chintan; López-Urrutia, José R. Crespo; Fujii, Keisuke; Steinbrügge, René; Stierhof, Jakob; Togawa, Moto; Harman, Zoltán; Oreshkina, Natalia S.; Cheung, Charles; Kozlov, Mikhail G.; Porsev, Sergey G.; Safronova, Marianna S.; Berengut, Julian C.; Rosner, Michael; Bissinger, Matthias; Ballhausen, Ralf; Hell, Natalie; Park, SungNam; Chung, Moses; Hoesch, Moritz; Seltmann, Jörn; Surzhykov, Andrey S.; Yerokhin, Vladimir A.; Wilms, Jörn; Porter, F. Scott; Stöhlker, Thomas; Keitel, Christoph H.; Pfeifer, Thomas; Brown, Gregory V.; Leutenegger, Maurice A.; Bernitt, Sven
Source
Phys. Rev. Lett. 124, 225001 (2020)
Subject
Language
Abstract
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.
Comment: Main text (6 pages, 3 figures), Supplmentary Material (8 pages, 4 figure), Published in Physical Review Letters
Comment: Main text (6 pages, 3 figures), Supplmentary Material (8 pages, 4 figure), Published in Physical Review Letters