The Pure Rotational Spectrum of Ko

Abstract

The pure rotational spectrum of potassium monoxide (KO) has been recorded using millimeter-wave direct absorption spectroscopy. KO was synthesized by the reaction of potassium vapor, produced in a Broida-type oven, with nitrous oxide. No DC discharge was necessary. Eleven rotational transitions belonging to the 2 Π 3/2 spin-orbit component have been measured and have been fit successfully to a case (c) Hamiltonian. Rotational and lambda-doubling constants for this spin-orbit component have been determined. It has been suggested that the ground electronic state of KO is either 2 Π (as for LiO and NaO) or 2 Σ (as for RbO and CsO), both of which lie close in energy. Recent computational studies favor a 2 Σ ground state. Further measurements of the rotational transitions of the 2 Π 1/2 spin-orbit component and the 2 Σ state are currently in progress, as well as the potassium hyperfine structure.