Ion-atom-atom three-body recombination: from the cold to the thermal regime

TL;DR

This study investigates ion-atom-atom three-body recombination across a broad energy spectrum, revealing how long-range and short-range interactions influence reaction outcomes in different energy regimes.

Contribution

It introduces a classical trajectory method in hyperspherical coordinates to analyze three-body reactions from cold to thermal energies, highlighting the energy-dependent transition in reaction dynamics.

Findings

Dissociation energy acts as a threshold between low and high energy regimes.

Long-range potential dominates at low energies, affecting reaction products.

Short-range interactions become significant at high energies, increasing molecular formation.

Abstract

We present a study on ion-atom-atom reaction A+A+B$^+$ in a wide range of systems and collision energies ranging from 100$~\mu$K to 10$^5~$K, analyzing the two possible products: molecules and molecular ions. The dynamics is performed via a direct three-body formalism based on a classical trajectory method in hyperspherical coordinates developed in [J. Chem. Phys. $\textbf{140}$, 044307 (2014)]. Our chief finding is that the dissociation energy of the molecular ion product acts as a threshold energy separating the low and high energy regimes. In the low energy regime, the long-range tail of the three-body potential dictates the fate of the reaction and the main reaction product. On the contrary, in the high energy regime, the short-range of atom-atom and atom-ion interaction potential dominates the dynamics, enhancing molecular formation for the low energy regime.