Associative detachment in anion-atom reactions involving a dipole-bound electron

Area of Science:

• Chemical Physics
• Atomic and Molecular Collisions
• Quantum Chemistry

Background:

• Associative electronic detachment (AED) is vital in chemical reactions within the interstellar medium, ionosphere, and biological systems.
• AED involves anions and neutral atoms, leading to electron detachment and neutral molecule formation.
• Understanding AED dynamics is crucial for modeling complex chemical environments.

Purpose of the Study:

• Investigate associative electronic detachment (AED) between hydroxide anions (OH-) and rubidium atoms.
• Precisely control the electronic excitation state of rubidium atoms during the collision.
• Elucidate the role of electronic excitation in the dynamics and stability of intermediate complexes.

Main Methods:

• Experimental investigation of AED reactions using controlled rubidium atom excitation.
• Precise measurement of reaction rate coefficients.
• Comparison of experimental data with ab initio calculations for validation.

Main Results:

• Reaction with ground-state rubidium forms stable intermediate complexes bound by dipolar forces.
• Ab initio calculations accurately predict measured rate coefficients, highlighting steric effects.
• Excited-state rubidium exhibits lower reaction rates, indicating dynamical stabilization mechanisms.

Conclusions:

• The study provides a rigorous test for ab initio calculations in anion-neutral collisions.
• Dynamical stabilization in excited states suppresses coupling to autodetachment pathways.
• A general framework is established for understanding electronic state-dependent dynamics in AEDs.