Spectroscopy of Ultracold 39K85Rb Triplet Rydberg Molecules through the a3Σ+ State formed by Photoassociation

We have observed vibrational levels of the 2
³
П state and the 3
³
Σ
⁺
state of
³⁹
K
⁸⁵
Rb through the a
³
Σ
⁺
state formed by photoassociation (PA) spectroscopy. Convenient state-selective detection methods for exploring triplet Rydberg states from the metastable a
³
Σ
⁺
state of ultracold KRb molecules by photoionization and time-of-flight mass spectroscopy are proposed.