What happens to atoms and molecules during x-ray free-electron laser pulses?

Sang-Kil Son

[BibTeX][slide: 10Mb]

X-ray free-electron lasers (XFELs) have brought an impact on various scientific fields, including AMO physics, material science, astrophysics, and molecular biology. Understanding how matter interacts with ultraintense x-ray pulses generated by XFELs is fundamental and crucial for most XFEL applications. In this talk, I will mainly discuss how to describe ionization and fragmentation dynamics of atoms and molecules when they are exposed to intense XFEL pulses. Because of the extremely high x-ray photon fluence within very short pulse duration, materials interacting with XFEL undergo significant radiation damage, i.e., they possibly become highly ionized and then explode. I will present a theoretical framework to treat x-ray-induced processes and to simulate radiation damage dynamics, introducing two dedicated toolkits, XATOM and XMOLECULE. Then I will present two recent studies, x-ray multiphoton ionization dynamics of Xe atoms and ultrafast explosion dynamics of iodine-containing polyatomic molecules. The former demonstrates an interplay between resonance and relativistic effects in the heavy-atom ionization dynamics, and the latter reveals x-ray molecular ionization enhancement via intramolecular charge transfer. Both of them provide critical insights of radiation damage dynamics of molecules containing heavy atoms at high x-ray intensity. With these examples, I will demonstrate how theory and experiment work together to advance XFEL science, and discuss how to apply these new findings for potential XFEL applications such as femtosecond x-ray nanocrystallography.

Tags: XATOM, XMOLECULE, MMID, REXMI, CREXIM, Xe, CH3I, XFEL, CFEL, DESY

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