Isotopic nitric oxide spectra and breakdown of the Born-Oppenheimer approximation

Abstract
Ground state millimetre and submillimetre wave transitions of the isotopically substituted nitric oxide isotopes 15N16O and 14N18O, as well as high-J rotational 14N16O frequencies in the far infrared, are measured. Improved ground state and equilibrium constants of these molecules are determined, and an indication of the breakdown of the Born-Oppenheimer approximation is detected.