Effect of two-center interference on molecular ionization in multiphoton ionization regime

Area of Science:

• Quantum Chemistry
• Atomic and Molecular Physics
• Strong Field Physics

Background:

• Investigating molecular ionization dynamics is crucial for understanding light-matter interactions.
• The orientation dependence of ionization provides insights into electron emission mechanisms.

Purpose of the Study:

• To investigate the orientation dependence of H2+ ionization in near-infrared laser fields.
• To compare different theoretical models for predicting ionization yields.

Main Methods:

• Solving the full three-dimensional time-dependent Schrödinger equation (TDSE) in prolate spheroidal coordinates.
• Utilizing length gauge and radiation gauge strong-field approximation (SFA) theories.
• Employing molecular ADK theory for comparison.

Main Results:

• Ionization probability shows distinct orientation dependencies in tunneling (decreases with alignment angle) and multiphoton (increases with orientation angle) regimes at R=2 a.u.
• TDSE results agree qualitatively with length gauge SFA but not with radiation gauge SFA or molecular ADK.
• Interference between electron wave packets from different molecular cores explains the observed orientation dependence, especially at low intensities.

Conclusions:

• The orientation dependence of H2+ ionization is governed by electron wave packet interference.
• Theoretical model choice significantly impacts the accuracy of ionization predictions.
• Internuclear distance influences the electron wavefunction distribution and consequently the ionization yields.