1. High-accuracy Measurements of Core-excited Transitions in Light Li-like Ions
- Author
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Togawa, Moto, Kühn, Steffen, Shah, Chintan, Zaystev, Vladimir A., Oreshkina, Natalia S., Buck, Jens, Bernitt, Sonja, Steinbrügge, René, Seltmann, Jörn, Hoesch, Moritz, Keitel, Christoph H., Pfeifer, Thomas, Leutenegger, Maurice A., and López-Urrutia, José R. Crespo
- Subjects
Physics - Atomic Physics - Abstract
The transition energies of the two $1s$-core-excited soft X-ray lines (dubbed q and r) from $1s^2 2s ^1S_{1/2}$ to the respective upper levels $1s(^{2}S)2s2p(^{3}P) ^{2}P_{3/2}$ and $^{2}P_{1/2}$ of Li-like oxygen, fluorine and neon were measured and calibrated using several nearby transitions of He-like ions. The major remaining source of energy uncertainties in monochromators, the periodic fluctuations produced by imperfect angular encoder calibration, is addressed by a simultaneously running photoelectron spectroscopy measurement. This leads to an improved energy determination of 5 parts per million, showing fair agreement with previous theories as well as with our own, involving a complete treatment of the autoionizing states studied here. Our experimental results translate to an uncertainty of only 1.6\,km/s for the oxygen line qr-blend used to determine the outflow velocities of active galactic nuclei, ten times smaller than previously possible., Comment: 7 pages, 4 figures
- Published
- 2024