Spectroscopic analysis of the coupled 1(1)Pi, 2(3)Sigma(+) (Omega=0(-), 1), and b(3)Pi (Omega=0(+/-), 1, 2) states of the KRb molecule using both ultracold molecules and molecular beam experiments

Abstract

We report the spectroscopic characterization of excited electronic states of KRb by combining spectra from molecular beam (MB) experiments with those from ultracold molecules (UM) formed by photoassociation (PA) of ultracold atoms. Spectra involving the 1(1)Pi, 2(3)Sigma(+), and b(3)Pi states in a strongly perturbed region have been identified. This approach provides a powerful method to identify the vibrational levels of the excited electronic states perturbed globally by neighboring electronic states. This is because the two sets of spectra from the UM and the MB experiments probe the same energy region from very different initial electronic states. The UM experiments utilize high v '' levels of the a(3)Sigma(+) state with large internuclear separations, while the MB experiments utilize low v '' levels of the ground X-1 Sigma(+) state with near-equilibrium internuclear separations. Only the Omega = 1 levels of the 2(3)Sigma(+) and b(3)Pi states are observed in the MB spectra, while the Omega = 0(-), 1 levels of the 2(3)Sigma(+) state and the Omega = 0(+/-), 1, 2 levels of the b(3)Pi state are observed in the UM spectra.