Model for the hyperfine structure of electronically-excited ${\rm KCs}$ molecules

TL;DR

This paper develops a model to analyze the hyperfine structure of excited KCs molecules, aiding in the creation of ultracold ground-state molecules by understanding their energy level splitting.

Contribution

It introduces a new model based on atomic hyperfine interactions to describe the hyperfine structure of excited KCs molecules across different internuclear distances.

Findings

Describes hyperfine structure of KCs molecules near dissociation limits.

Provides a framework for calculating rovibrational hyperfine levels.

First step towards identifying pathways for ultracold molecule formation.

Abstract

A model for determining the hyperfine structure of the excited electronic states of diatomic bialkali heteronuclear molecules is formulated from the atomic hyperfine interactions, and is applied to the case of bosonic $^{39}$KCs and fermionic $^{40}$KCs molecules. The hyperfine structure of the potential energy curves of the states correlated to the K($4s\,^2S_{1/2}$)+Cs($6p\,^2P_{1/2,3/2}$) dissociation limits is described in terms of different coupling schemes depending on the internuclear distance $R$. These results provide the first step in the calculation of the hyperfine structure of rovibrational levels of these excited molecular states in the perspective of the identification of efficient paths for creating ultracold ground-state KCs molecules.