Exploring coherent electron excitation and migration dynamics by electron diffraction with ultrashort X-ray pulses

Area of Science:

• Physical Chemistry
• Quantum Dynamics
• Molecular Imaging

Background:

• Ultrafast charge migration is crucial for understanding chemical reactions and biological processes.
• Monitoring electron dynamics at the attosecond timescale is essential for detailed mechanistic insights.

Purpose of the Study:

• To present a novel method for monitoring attosecond charge migration in molecules.
• To achieve high spatial and temporal resolutions in observing electronic dynamics.

Main Methods:

• Utilizing ab initio numerical simulations.
• Employing an ultraviolet pump pulse to create electronic coherence.
• Using a time-delayed attosecond X-ray pulse for molecular ionization and electron diffraction measurements.

Main Results:

• Observed asymmetric diffraction patterns in X-ray photoelectron spectra dependent on pump-probe time delay.
• Demonstrated that diffraction patterns encode information on molecular orbital symmetry and chemical bonding.
• Showcased periodical distortions in diffraction patterns illustrating electronic coherence evolution.

Conclusions:

• Developed an electronic time-dependent ultrafast molecular photoionization model for coherent superposition states.
• Established electron diffraction as a viable tool for attosecond imaging of ultrafast molecular processes.
• Provided a method to track charge migration dynamics with unprecedented temporal resolution.