Cold three-body collisions in hydrogen-hydrogen-alkali atomic system

TL;DR

This study investigates three-body collisions in hydrogen-alkali systems, revealing stable XH molecules, a single bound state for J^Pi=0^+, and calculating collision rates and cross-sections up to 0.5 K.

Contribution

It provides detailed calculations of collision rates, bound states, and stability of XH molecules in hydrogen-alkali three-body systems, expanding understanding of their collision dynamics.

Findings

Only one XH molecular state exists for spin-stretched alkali atoms.

Recombination leads to stable XH molecules with no vibrational relaxation.

One three-body bound state for J^Pi=0^+; none for higher angular momenta.

Abstract

We have studied hydrogen-hydrogen-alkali three-body systems in the adiabatic hyperspherical representation. For the spin-stretched case, there exists a single $X$H molecular state when $X$ is one of the bosonic alkali atoms: $^7$Li, $^{23}$Na, $^{39}$K, $^{87}$Rb and $^{133}$Cs. As a result, the {\em only} recombination process is the one that leads to formation of $X$H molecules, H+H+$X$$\rightarrow$$X$H+H, and such molecules will be stable against vibrational relaxation. We have calculated the collision rates for recombination and collision induced dissociation as well as the elastic cross-sections for H+$X$H collisions up to a temperature of 0.5 K, including the partial wave contributions from $J^\Pi$=$0^+$ to $5^-$. We have also found that there is just one three-body bound state for such systems for $J^\Pi$=$0^+$ and no bound states for higher angular momenta.