Collisional state-changing of OH$^-$ rotations by interaction with Rb atoms in cold traps

TL;DR

This study calculates collisional cross sections and rates for OH$^-$ ions interacting with Rb atoms at low temperatures, providing insights into rotational state changes relevant for cold trap experiments.

Contribution

It introduces an accurate ab initio potential energy surface for OH$^-$ and Rb interactions, enabling detailed calculations of collisional dynamics at low temperatures.

Findings

Computed elastic and inelastic cross sections for OH$^-$ and Rb interactions.

Derived cooling and heating rates up to 35 K.

Compared results with previous He-based experiments.

Abstract

We employ an accurate, ab initio potential energy surface (PES) which describes the electronic interaction energy between the molecular anion OH$^-$ ($^1\Sigma^+$) and the neutral rubidium atom Rb ($^2S$), to evaluate the elastic and inelastic cross sections over a range of energies representative of the conditions of low-T experiments in MOT traps, when combined with laser-cooled rubidium gas. The system is considered to be in its vibrational ground state, while the first four rotational levels are taken to be involved in the cooling and heating collisional processes that are computed here. The corresponding cooling and heating rates up to about 35 K are obtained from the calculations and compared with the recent results in a similar experiments, where He was the partner atom of the current anion.