Imaging Resonance Effects in C + H₂ Collisions Using a Zeeman Decelerator.

Area of Science:

• Chemical Physics
• Atomic and Molecular Collisions
• Quantum Mechanics

Background:

• Scattering resonances arise from bound states in molecular interactions at low energies.
• Resonance effects are highly sensitive to interaction potentials, serving as crucial tests for theoretical models.

Purpose of the Study:

• To present high-resolution measurements of state-resolved angular scattering distributions for inelastic collisions.
• To investigate collisions between Zeeman-decelerated carbon atoms (C(3P1)) and para-hydrogen molecules (para-H2).
• To probe scattering behavior at low collision energies (0.5–77 cm⁻¹).

Main Methods:

• Utilized Zeeman deceleration for state-selected C(3P1) atoms.
• Performed high-resolution measurements of angular scattering distributions.
• Conducted ab initio quantum scattering calculations for comparison.

Main Results:

• Observed rapid variations in angular distributions attributed to partial wave reduction and resonance effects.
• Demonstrated excellent agreement between experimental data and theoretical predictions.
• Identified discrepancies at specific energies, likely due to inaccuracies in predicted quasi-bound states.

Conclusions:

• Experimental results validate theoretical models for low-energy collisions.
• Discrepancies highlight the need for refinement in predicting quasi-bound states.
• Opens avenues for high-precision, low-energy studies of paramagnetic species collisions.