Universal model for exoergic bimolecular reactions and inelastic processes

TL;DR

This paper introduces a comprehensive quantum-mechanical model for exoergic bimolecular reactions and inelastic processes that spans from ultracold to higher temperatures, bridging quantum and classical chemistry.

Contribution

It provides an analytic, fully quantum model that connects ultracold chemistry with classical models, applicable across a wide temperature range.

Findings

The model agrees with quantum threshold behavior at ultracold temperatures.

It predicts a non-monotonic temperature dependence of reaction rates.

Rates for different molecular types show a minimum before increasing with temperature.

Abstract

From a rigorous multichannel quantum-defect formulation of bimolecular processes, we derive a fully quantal and analytic model for the total rate of exoergic bimolecular reactions and/or inelastic processes that is applicable over a wide range of temperatures including the ultracold regime. The theory establishes a connection between the ultracold chemistry and the regular chemistry by showing that the same theory that gives the quantum threshold behavior agrees with the classical Gorin model at higher temperatures. In between, it predicts that the rates for identical bosonic molecules and distinguishable molecules would first decrease with temperature outside of the Wigner threshold region, before rising after a minimum is reached.