Rostock 2019 – wissenschaftliches Programm

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SYXR: Symposium Atomic Physics, Molecular Physics, and Quantum Optics with X-ray FELs

SYXR 1: Atomic Physics, Molecular Physics and Quantum Optics with X-ray FELs

SYXR 1.4: Hauptvortrag

Donnerstag, 14. März 2019, 15:30–16:00, U Audimax

X-Ray Multiphoton Ionization of Atoms and Molecules — •Daniel Rolles — J.R. Macdonald Laboratory, Kansas State University, Manhattan, KS, USA

X-ray free-electron lasers (XFELs) provide extremely intense, short-pulse X-ray radiation, making it possible to study X-ray-matter interaction at intensities close to 10²⁰ W/cm². To explore the response of atoms and molecules to these unprecedented X-ray intensities, we have extended our investigations of the multiphoton ionization of heavy atoms and of high-Z atom containing molecules from the soft into the hard X-ray range and to higher peak fluences than in previous studies. The results provide important benchmarks, e.g, for calculating radiation damage effects in XFEL-based X-ray imaging experiments. We observe a significant enhancement of the degree of ionization in molecules as compared to the equivalent, individual atoms and trace this effect to ultrafast charge transfer from the neighboring atoms in the molecule [1]. The comparison to new calculations, which quantitatively reproduce the experimental data at all photon energies and intensities, also highlights the role of resonant and relativistic effects in the X-ray multiphoton ionization of heavy atoms [2].

[1] A. Rudenko et al., Nature 546, 129 (2017) [2] B. Rudek et al., Nature Commun. 9, 4200 (2018)