Angle-dependent electron-electron correlation in the single ionization of H₂ in strong laser fields

Area of Science:

• Quantum mechanics
• Atomic and molecular physics
• Strong-field physics

Background:

• Understanding electron behavior in molecules under intense laser fields is crucial for controlling chemical reactions and developing new spectroscopic techniques.
• Hydrogen molecule (H2) serves as a fundamental model system for studying electron dynamics due to its simplicity.

Purpose of the Study:

• To investigate the one-photon and tunneling ionization mechanisms of H2 under strong XUV and infrared laser pulses.
• To explore the role of electron-electron correlation in these ionization processes.
• To analyze the influence of laser parameters and molecular orientation on ionization dynamics.

Main Methods:

• Numerical simulation of the four-dimensional time-dependent Schrödinger equation.
• Inclusion of two-electron dynamics.
• Consideration of arbitrary angles between the molecular axis and laser polarization.

Main Results:

• In one-photon ionization, one electron escapes while the other remains in a coherent superposition of states.
• In tunneling ionization, one electron tunnels through the barrier, and the other adapts to the potential, often transferring to the ground state.
• Electron-electron correlation is highly sensitive to laser frequency, intensity, and molecular orientation in the intermediate regime.

Conclusions:

• The ionization pathways of H2 are distinct for one-photon and tunneling regimes, with significant differences in the behavior of the bound electron.
• Electron-electron correlation plays a critical role in shaping ionization dynamics, particularly in the transition between different ionization regimes.
• The study highlights the importance of considering multi-electron effects and molecular orientation for accurate modeling of strong-field ionization.