Two-body loss rates for reactive collisions of cold atoms

TL;DR

This paper develops a two-channel model for cold atom reactive collisions, providing analytical expressions for cross sections and loss rates, and applies it to neon atom collisions with results matching numerical data.

Contribution

Introduces a universal two-channel model for reactive cold atom collisions with explicit formulas and applies it to neon atom systems, aligning well with numerical solutions.

Findings

Derived universal shape functions for cross sections and loss rates.

Validated the model against numerical multichannel Schrödinger equation solutions.

Achieved excellent agreement between analytical shape functions and synthetic scattering data.

Abstract

We present an effective two-channel model for reactive collisions of cold atoms. It augments elastic molecular channels with an irreversible, inelastic loss channel. Scattering is studied with the distorted-wave Born approximation and yields general expressions for angular momentum resolved cross sections as well as two-body loss rates. Explicit expressions are obtained for piece-wise constant potentials. A pole expansion reveals simple universal shape functions for cross sections and two-body loss rates in agreement with the Wigner threshold laws. This is applied to collisions of metastable ${^{20}}$Ne -- ${^{21}}$Ne atoms, which decay primarily through exothermic Penning-, or Associative- ionization processes. From a numerical solution of the multichannel Schr\"odinger equation using the best currently available molecular potentials, we have obtained synthetic scattering data. Using the two-body loss shape functions derived in this paper, we can match these scattering data very well.