Universal threshold law for ion-neutral-neutral three-body recombination

TL;DR

This paper applies a recent classical trajectory method to low-energy ion-neutral-neutral collisions, deriving a universal threshold law for three-body recombination that aligns with experimental and numerical results.

Contribution

It introduces a new threshold law for three-body recombination in ion-neutral-neutral systems at low energies, validated by experiments and simulations.

Findings

Threshold law accurately predicts recombination cross sections.

Weakly bound dimers are the dominant products.

Molecular ions surpass neutrals as main products at low energies.

Abstract

A very recently method for classical trajectory calculations for three-body collision [J. P\'{e}rez-R\'{i}os, S. Ragole, J. Wang and C. H. Greene, J. Chem. Phys. {\bf 140}, 044307 (2014)] has been applied to describe ion-neutral-neutral ternary processes for low energy collisions: 0.1 mK - 10 mK. As a result, a threshold law for the three-body recombination cross section is obtained and corroborated both, experimentally and numerically. The derived threshold law predicts the formation of weakly bound dimers, with binding energies comparable to the collision energy of the collisional partners. In this low energy range, this analysis predicts that molecular ions should dominate over molecular neutrals as the most products formed.