Microwave-optical double resonance of HNO in the Ã1A″(000) state

Twenty-nine rotational transitions of HNO in the Ã1A″(000) excited state have been measured by microwave-optical, and radio-frequency-optical double resonance spectroscopy. Most of the observed lines are found to be perturbed by a few to a few hundred MHz. Improved values have been obtained for the rotational constants B and C and for the centrifugal distortion constant δJ. MODR lines have also been observed between levels of the Ã1A″ excited state, high rovibronic levels of the [Formula: see text] ground state, and levels of the ã3A″ state. One of the lines shows a larger magnetic effect, suggesting a perturbation by a level of the ã3A″ state.