Mirroring doubly excited resonances in argon

Area of Science:

• Atomic physics
• Quantum mechanics
• Spectroscopy

Background:

• Low-energy photoionization spectra provide insights into atomic electronic structure.
• Understanding doubly excited resonances is crucial for atomic physics.
• Previous theoretical predictions suggested specific resonance behaviors in argon.

Purpose of the Study:

• To investigate new features in the low-energy photoionization spectrum of argon.
• To combine high photon resolution and differential photoelectron spectroscopy for detailed analysis.
• To experimentally verify theoretical predictions regarding doubly excited resonances.

Main Methods:

• Utilizing high photon resolution techniques.
• Employing differential photoelectron spectroscopy.
• Analyzing the photoionization spectrum of argon (Ar).

Main Results:

• Observed two LS-forbidden doubly excited resonances in the 3p(-1)(3/2, 1/2) partial cross sections of argon.
• These resonances exhibited mirroring profiles.
• Complete cancellation of these resonances was observed in the total photoionization cross section, matching theoretical predictions.

Conclusions:

• Confirmed the existence of a new class of weakly spin-orbit induced, mirroring resonances.
• These resonances are observable in partial cross sections but not in total cross sections.
• The findings have implications for understanding collisional cross sections in atoms, molecules, and solids.