The coupling of the X$^{1}\Sigma ^{+}$ and a$^{3}\Sigma ^{+}$ states of KRb

TL;DR

This paper presents a detailed spectroscopic and coupled channels analysis of the electronic states in KRb, providing accurate potential energy curves and predictions for scattering properties relevant to cold collision experiments.

Contribution

It introduces a comprehensive coupled channels fitting method combining spectroscopic data and Feshbach resonance positions to derive precise molecular potentials for KRb.

Findings

Accurate potential energy curves for the extsuperscript{1}\Sigma^{+} and extsuperscript{3}\Sigma^{+} states of KRb.

Predictions of scattering lengths and Feshbach resonances for various isotopic combinations.

Enhanced understanding of cold collision features in KRb molecules.

Abstract

A comprehensive study of the electronic states at the 4s+5s asymptote in KRb is presented. Abundant spectroscopic data on the \astate state were collected by Fourier-transform spectroscopy which allow to determine an accurate experimental potential energy curve up to 14.8 \AA . The existing data set (C. Amiot et al. J. Chem. Phys. 112, 7068 (2000)) on the ground state \Xstate was extended by several additional levels lying close to the atomic asymptote. In a coupled channels fitting routine complete molecular potentials for both electronic states were fitted. Along with the line frequencies of the molecular transitions, recently published positions of Feshbach resonances in $^{40}$K and $^{87}$Rb mixtures (F. Ferlaino et al. Phys. Rev. A 74, 039903 (2006)) were included in the fit. This makes the derived potential curves capable for an accurate description of observed cold collision features so far. Predictions of scattering lengths and Feshbach resonances in other isotopic combinations are reported.