Theoretical study of the I$^{+}$ + I$^{-}$ mutual neutralization reaction

TL;DR

This paper presents a theoretical calculation of the cross sections for the mutual neutralization reaction between I$^{+}$ and I$^{-}$ over a range of collision energies, using advanced quantum chemistry and semi-classical methods.

Contribution

It provides detailed cross section data for multiple neutral and ionic states of iodine, using relativistic multi-reference calculations and Landau Zener surface hopping, aligning with recent experimental results.

Findings

Cross sections computed for various iodine states.

Agreement with recent experimental measurements.

Data useful for modeling iodine plasma kinetics.

Abstract

We have computed the cross sections of the mutual neutralization reaction between I$^{+}$ and I$^{-}$ for a collision energy varying from 0.001 eV to 50 eV. These cross sections were obtained using the adiabatic potential energy curves of the I$_{2}$ system computed with a direct relativistic Multi-Reference Configuration Interaction method and a semi-classical approach (i.e. Landau Zener Surface Hopping). We report the cross sections towards the following neutral states: $\text{I}(^{2}P_{3/2})+\text{I}(^{2}P_{3/2})$, $\text{I}(^{2}P_{3/2})+\text{I}(^{2}P_{1/2})$, $\text{I}(^{2}P_{1/2})+\text{I}(^{2}P_{1/2})$ and $\text{I}(5p^{4}6s)+\text{I}(^{2}P_{3/2})$. We also discuss the cross sections towards the two following excited ionic states : $\text{I}^{-}(^{1}S_{0})+\text{I}^{+}(^{3}P_{0})$ and $\text{I}^{-}(^{1}S_{0})+\text{I}^{+}(^{3}D_{2})$. The results of these calculations are in accordance with recent experimental measurements conducted in the double ion ring DESIREE in Stockholm. These results can be used to model iodine plasma kinetics and thus to improve our understanding of the latter.