Nondipolar electron angular distributions from fixed-in-space molecules

Area of Science:

• Atomic and Molecular Physics
• Quantum Chemistry
• Photochemistry

Background:

• Photoelectron angular distributions (PADs) are crucial for understanding molecular electronic structure.
• Nondipole effects, deviations from dipole approximation, are typically small but can be significant in specific molecular contexts.
• Studying fixed-in-space molecules provides a unique frame for observing subtle anisotropic effects.

Purpose of the Study:

• To present the first experimental evidence of nondipole effects in the azimuthal dependence of PADs for fixed-in-space nitrogen molecules (N2).
• To compare experimental results with theoretical predictions for both randomly oriented and fixed molecules.
• To assess the adequacy of current theoretical models in describing molecular frame PADs.

Main Methods:

• Photoelectron spectroscopy on fixed-in-space N2 molecules.
• Measurement of azimuthal dependence of photoelectron angular distributions.
• Comparison with theoretical calculations, including first-order nondipole corrections.

Main Results:

• Observed clear indications of nondipole effects in the azimuthal PADs of N2.
• Found discrepancies between experimental data and theoretical predictions, even with first-order nondipole corrections.
• Highlighted the limitations of current theoretical approaches for molecular frame PADs.

Conclusions:

• The study demonstrates the importance of nondipole effects in molecular photoionization.
• Higher-order theoretical corrections are likely necessary to accurately model molecular frame PADs.
• Experimental and theoretical advancements are needed for a comprehensive understanding of nondipole phenomena in molecules.