X-ray fluorescence spectrum of highly charged Fe ions driven by strong free-electron-laser fields. (13th April 2016)

• Record Type: Journal Article
• Authors: Oreshkina, Natalia S; Cavaletto, Stefano M; Keitel, Christoph H; Harman, Zoltán
• Is Part Of: Journal of physics. Volume 49:Number 9(2016:May 01)
• Publication Date: 2016-04-13
• Subjects: 3C/3D lines in Fe -- dynamical processes -- QED corrections -- atomic-structure calculations -- ion–x-ray interaction -- line-strength ratio; Atoms -- Periodicals; Molecules -- Periodicals; Optics -- Periodicals; Nuclear physics -- Periodicals; 539.6
• DOI: 10.1088/0953-4075/49/9/094003
• Languages: English
• ISSNs: 0953-4075

Abstract

Abstract: The influence of nonlinear dynamical effects is analyzed on the observed spectra of controversial 3C and 3D astrophysically relevant x-ray lines in neonlike Fe 16 + and the A, B, and C lines in natriumlike Fe 15 + ions. First, a large-scale configuration-interaction calculation of oscillator strengths is performed with the inclusion of higher-order electron-correlation effects. Also, quantum-electrodynamic corrections to the transition energies are calculated. Further considered dynamical effects provide a possible resolution of the discrepancy between theory and experiment found by recent x-ray free-electron-laser measurements of these controversial lines. We find that, for strong x-ray sources, the modeling of the spectral lines by a peak with an area proportional to the oscillator strength is not sufficient and nonlinear dynamical effects have to be taken into account. Thus, we advocate the use of light–matter-interaction models also valid for strong light fields in the analysis and interpretation of the associated astrophysical and laboratory spectra. We investigate line-strength ratios distinguishing between the coherent and incoherent parts of the emission spectrum. In addition, the spectrum of Fe 15 +, an autoionizing ion which was also present in the recent laboratory experiment, is analyzed as well.