Laser-induced electron diffraction for probing rare gas atoms.

Area of Science:

• Atomic, Molecular, and Optical Physics
• Ultrafast Science
• Chemical Physics

Background:

• Femtosecond time-resolved molecular imaging is a key goal in ultrafast science.
• Laser-induced electron diffraction (LIED) has emerged as a promising technique for capturing molecular dynamics.
• Previous studies demonstrated LIED for molecular snapshots, necessitating a deeper understanding of the underlying atomic processes.

Purpose of the Study:

• To provide a comprehensive treatment of the atomic laser-induced electron diffraction (LIED) response.
• To extract electron-ion differential cross sections (DCSs) for rare gas atoms.
• To establish the foundational elements for generalizing LIED to complex molecular imaging.

Main Methods:

• Utilizing intense midinfrared lasers to generate high-energy electron momentum distributions from rare gas atoms.
• Measuring angular-resolved electron momentum distributions following strong-field ionization.
• Extracting electron-ion differential cross sections (DCSs) from the measured distributions.

Main Results:

• High-energy electrons arise from elastic rescattering of field-driven wave packets with parent ions.
• Extracted DCSs for neutral atoms and ions were indistinguishable at recollision energies ≥100 eV, confirming close collision dynamics.
• The measured DCSs demonstrated independence from laser parameters, aligning with theoretical predictions.

Conclusions:

• The study successfully extracts atomic electron-ion differential cross sections, validating the LIED mechanism.
• The findings confirm the close collision nature of electron-ion interactions in LIED.
• This work lays the groundwork for applying LIED to achieve femtosecond molecular imaging.