Pure rotational spectrum of gold monoxide (AuO) in the X 2Π3/2 state

The pure rotational spectrum of AuO in the X 2Π3/2 state was observed by employing a source-modulated microwave spectrometer. The AuO radical was generated in a free space cell by the sputtering reaction from a gold sheet lining the inner surface of a stainless steel cathode using a dc glow plasma of O2 and Ar. Observation of the rotational transitions in both the ground and first excited vibrational states enabled to determine molecular constants by a least-squares fit. Other spectroscopic parameters such as equilibrium bond length, re, and vibrational wavenumber, ωe, were also derived from the obtained molecular constants.