A New Insight on Stereo-Dynamics of Penning Ionization Reactions

Area of Science:

• Atomic and Molecular Physics
• Chemical Physics
• Reaction Dynamics

Background:

• Penning ionization (PI) reactions are crucial for understanding atomic and molecular interactions.
• Stereo-dynamics, or the dependence on orientation, plays a key role in microscopic reaction mechanisms.
• Metastable Neon atoms (Ne*) interacting with noble gases reveal insights into electronic structure and orbital interactions.

Purpose of the Study:

• To investigate the stereo-dynamics of Penning ionization reactions.
• To understand the influence of reagent and product orbital orientations on reaction probability.
• To characterize state-to-state reaction probabilities for the ionization of Krypton (Kr) and Xenon (Xe) by metastable Neon atoms (Ne*).

Main Methods:

• Experimental study of Penning ionization reactions.
• Focus on collisions between metastable Ne*(3P2,0) atoms and noble gas atoms (Kr, Xe).
• Analysis of Penning Ionization Electron Spectra (PIES) to resolve spin-orbit states of reagents and products.

Main Results:

• Reaction probability depends on the relative orientation of atomic and molecular orbitals.
• Identified four reaction channels for Ne* ionization of Kr and Xe, involving specific spin-orbit states.
• Demonstrated a change in reactivity of Ne*(3P0) versus Ne*(3P2) atoms as a function of collision energy.
• Characterized state-to-state reaction probabilities for Ne* ionization of Kr and Xe for the first time.

Conclusions:

• Orbital orientation significantly influences Penning ionization stereo-dynamics.
• Collision energy critically affects the balance between adiabatic and non-adiabatic effects, governing reaction outcomes.
• Detailed state-to-state probabilities provide a fundamental understanding of these complex ionization processes.