Unveiling the X-ray-Induced Rabi Dynamics in Resonant Auger Fragment Spectra.

Area of Science:

• Ultrafast dynamics
• Molecular spectroscopy
• X-ray science

Background:

• Vibrationally resolved resonant Auger spectroscopy (RAS) probes molecular core-excited states.
• RAS on bound-continuum transitions is sensitive to ultrafast dissociation.
• Fragment bands in RAS originate from Auger decay in dissociation fragments.

Purpose of the Study:

• Theoretically investigate fragment band formation driven by ultrashort X-ray pulses.
• Analyze the behavior of fragment RAS peaks under strong X-ray Rabi oscillations.
• Develop a method to observe Rabi oscillations in molecular fragmentation.

Main Methods:

• Theoretical investigation of fragment band formation.
• Numerical simulations using ultrashort X-ray pulses.
• Combining RAS with kinetic energy release (KER) spectra.

Main Results:

• Fragment RAS peaks show insensitivity to strong X-ray Rabi oscillations, unlike conventional molecular bands.
• Numerical simulations on water molecules demonstrate clear observation of Rabi oscillations.
• Rabi oscillation observation is enabled when pulse broadening is less than fragment vibrational frequencies.

Conclusions:

• A framework is established for controlling ultrafast electron-nuclear dynamics in molecular fragmentation.
• RAS combined with KER spectra provides a powerful tool for studying X-ray-driven processes.
• This research advances the understanding of molecular dissociation dynamics under intense X-ray fields.