Superoxide anion (O$_{2}\negthinspace^{-}$) collisions with CO$_{2}$ molecules in the energy range 50-950 eV

TL;DR

This study investigates collisions between superoxide anions and CO₂ molecules across a broad energy range, measuring various cross sections and identifying formation of complex ions, supported by ab initio theoretical analysis.

Contribution

It provides new experimental data on electron detachment and ionization in O₂⁻ + CO₂ collisions, and proposes a mechanism for formation of stable cationic complexes.

Findings

Measured total electron detachment and ionization cross sections from 50 to 950 eV.

Detected high mass charged complexes above 500 eV impact energy.

Theoretically proposed formation of CO₃⁺ and CO₄⁺ stable complexes.

Abstract

A novel gas-phase molecular scattering study is reported for O$_{2}\negthinspace^{-}$ colliding with CO$_{2}$ for impact energies ranging from 50 to 950 eV. The absolute total electron detachment, relative total and partial ionization cross sections have been measured within this energy range and the positive ion yield of those produced during the collisions has been obtained. The primary anionic beam projectile is produced in a pulsed hollow cathode discharge induced plasma, and its interactions with the neutral molecular target occur in a gas cell at a well-known constant pressure. For impact energies above 500 eV high mass (m $>$ 44 u) charged complexes have been detected. With the aid of a theoretical study, using ab initio methods, we propose a mechanism to infer on the formation of these cationic species, which have been assigned as projectile-target stable compounds (CO$_{3}\negthinspace^{+}$ and CO$_{4}\negthinspace^{+}$).