Predicting and verifying transition strengths from weakly bound molecules

TL;DR

This study accurately predicts transition strengths from ultracold weakly bound molecules by constructing a precise excited state potential, demonstrating the importance of potential accuracy in understanding molecular transition behaviors.

Contribution

The paper introduces a refined potential energy curve for the excited state of ultracold molecules, enabling precise predictions of transition strengths from weakly bound states.

Findings

Achieved 0.14% accuracy in vibrational level spacing

Achieved 0.3% accuracy in rotational constants

Predicted large variations in transition strengths based on potential accuracy

Abstract

We investigated transition strengths from ultracold weakly bound 41K87Rb molecules produced via the photoassociation of laser-cooled atoms. An accurate potential energy curve of the excited state (3)1Sigma+ was constructed by carrying out direct potential fit analysis of rotational spectra obtained via depletion spectroscopy. Vibrational energies and rotational constants extracted from the depletion spectra of v'=41-50 levels were combined with the results of the previous spectroscopic study, and they were used for modifying an ab initio potential. An accuracy of 0.14% in vibrational level spacing and 0.3% in rotational constants was sufficient to predict the large observed variation in transition strengths among the vibrational levels. Our results show that transition strengths from weakly bound molecules are a good measure of the accuracy of an excited state potential.