X-ray induced electron and ion fragmentation dynamics in IBr

Area of Science:

• Atomic and Molecular Physics
• X-ray Physics
• Chemical Physics

Background:

• Inner-shell decay processes in heavy elements are critical for understanding x-ray damage.
• These processes are relevant for medical applications involving Auger-electron-emitting radionuclides.
• Characterizing these decays informs molecular and material science.

Purpose of the Study:

• To characterize the inner-shell decay processes in molecules containing heavy elements, specifically IBr.
• To measure charge states and kinetic energies of fragment ions (I and Br) after 1s ionization.
• To develop a computational model simulating these complex decay cascades.

Main Methods:

• Utilized x-ray/ion coincidence spectroscopy to study 1s ionization at the I and Br K-edges of IBr.
• Measured charge states and kinetic energies of correlated fragment ions.
• Developed a computational model combining Monte-Carlo/Molecular-Dynamics (MC/MD) simulations with a classical over-the-barrier model.

Main Results:

• Presented detailed charge states and kinetic energies of I^q+ and Br^q'⁺ atomic ions.
• Characterized fragment ion correlations arising from core-excited states during decay cascades.
• The computational model successfully tracked inner-shell cascades and predicted ion dynamics.

Conclusions:

• Inner-shell ionization and subsequent decay cascades in IBr lead to molecular dissociation into energetic atomic ions.
• The developed MC/MD model accurately simulates the complex dynamics of electron redistribution and nuclear motion.
• This research provides fundamental insights into x-ray-induced molecular processes.