Quantum Langevin model for exoergic ion-molecule reactions and inelastic processes

TL;DR

This paper develops a fully quantum Langevin model for ion-molecule reactions, accurately describing rates from high to ultracold temperatures, and providing the first analytic ultracold regime description.

Contribution

It introduces a quantum Langevin model derived from multichannel quantum defect theory, extending classical models to ultracold conditions.

Findings

Model agrees with classical Langevin at high temperatures.

Provides the first analytic ultracold reaction rate description.

Bridges classical and quantum regimes for ion-molecule reactions.

Abstract

We presents a fully quantal version of the Langevin model for the total rate of exoergic ion-molecule reactions or inelastic processes. The model, which is derived from a rigorous multichannel quantum-defect formulation of bimolecular processes, agrees with the classical Langevin model at sufficiently high temperatures. It also gives the first analytic description of ion-molecule reactions and inelastic processes in the ultracold regime where the quantum nature of the relative motion between the reactants becomes important.