The molecular constants and potential energy curve of the D1Π state in KLi

Polarisation labelling spectroscopy has been used to record the excitation spectrum of KLi in the region 18 500 to 20 800 cm−1. Transitions are observed to all bound levels of the D1Π state, and to some high vibrational levels of the C1Σ+ state, both of which dissociate to K(4S) + Li(2P) atoms. Spectroscopic constants are given for both electronic states. A pointwise potential curve is constructed for the D1Π state, which has a small barrier (26.5 cm−1) to dissociation, located at 7.79 Å.