Accurate near-threshold model for ultracold KRb dimers from interisotope Feshbach spectroscopy

TL;DR

This paper develops an improved near-threshold model for ultracold K-Rb dimers by analyzing interisotope Feshbach resonances, enhancing understanding of bound states and scattering properties relevant for ultracold molecule experiments.

Contribution

It introduces a refined model based on interisotope spectroscopy that accurately determines bound states and near-threshold parameters for K-Rb pairs, confirming the Born-Oppenheimer approximation.

Findings

Determined the number of bound states in singlet/triplet potentials.

Established precise near-threshold parameters for K-Rb pairs.

Validated the Born-Oppenheimer approximation at current accuracy.

Abstract

We investigate magnetic Feshbach resonances in two different ultracold K-Rb mixtures. Information on the K(39)-Rb(87) isotopic pair is combined with novel and pre-existing observations of resonance patterns for K(40)-Rb(87). Interisotope resonance spectroscopy improves significantly our near-threshold model for scattering and bound-state calculations. Our analysis determines the number of bound states in singlet/triplet potentials and establishes precisely near threshold parameters for all K-Rb pairs of interest for experiments with both atoms and molecules. In addition, the model verifies the validity of the Born-Oppenheimer approximation at the present level of accuracy.