Direct three body dynamics govern ion atom recombination and barrierless termolecular reactions

TL;DR

This paper shows that barrierless three-body reactions are governed by direct three-body dynamics, challenging traditional models, and provides a new framework supported by classical trajectory calculations.

Contribution

It introduces a fundamental mechanistic framework for barrierless termolecular reactions based on direct three-body dynamics, validated by classical trajectory simulations.

Findings

Reproduces ion atom recombination kinetics across temperatures without intermediate complexes.

Resolves discrepancies between traditional theory and experimental results.

Establishes a new mechanistic understanding applicable to various fields.

Abstract

For over a century, termolecular, or third order, chemical reactions have been explained by the Lindemann Hinshelwood mechanism, assuming sequential stabilization via bimolecular encounters. Here, we demonstrate that barrierless termolecular reactions are fundamentally governed by direct three body dynamics. Using classical trajectory calculations in hyperspherical coordinates, we quantitatively reproduce ion atom recombination kinetics across a wide temperature range without invoking intermediate complexes or steady state assumptions. Our results not only resolve longstanding discrepancies between theory and experiment, but also establish a general mechanistic framework for barrierless termolecular reactions, with implications spanning atmospheric chemistry, plasma physics, and ultracold chemistry.