Intensity dependence in nonsequential double ionization of helium

Area of Science:

• Atomic, Molecular, and Optical Physics
• Quantum Dynamics
• Strong-Field Physics

Background:

• Nonsequential double ionization (NDI) of atoms is a complex quantum phenomenon.
• Understanding electron correlation is crucial for describing NDI.
• Experimental observations show distinct structures in electron momentum distributions.

Purpose of the Study:

• To investigate the correlated two-electron momentum distributions in helium NDI.
• To explain the origin of the experimentally observed V-shaped structure.
• To explore the role of rescattering and electron-electron repulsion in NDI.

Main Methods:

• Utilized the quantitative rescattering (QRS) model for simulations.
• Simulated NDI of helium using 800 nm laser pulses.
• Analyzed electron momentum distributions at intensities from 2-15 × 10^14 W/cm^2.

Main Results:

• The QRS model successfully reproduces the V-shaped structure in momentum distributions.
• The V-shape is attributed to strong forward scattering during laser-induced recollision.
• Asymmetric momentum distributions from excited states and final-state electron repulsion contribute to the V-shape.

Conclusions:

• The study elucidates the underlying mechanisms of the V-shaped structure in helium NDI.
• Recollision excitation and electron-electron interactions are key factors.
• The QRS model provides a robust framework for studying strong-field atomic processes.