High resolution electronic spectroscopy of Ne·OH

The high resolution electronic spectrum of Ne·OH has been recorded in a supersonic free jet expansion using the laser-induced fluorescence technique. From an analysis of the spectrum which yields rotational constants, we are able to obtain Ne·OH bond lengths in several vibrational (hindered rotor) levels of the excited state and the vibrationless level of the ground state. We also measure the Fermi contact constant in the à state which is, unlike Ar·OH, insignificantly perturbed from the value in the OH monomer. However, we now measure a parity doubling of the X̃ state rotational levels which is tenfold larger than the upper limit we established for such an interaction in Ar·OH. We interpret these latter measurements to imply weaker and more isotropic bonding in Ne·OH compared to Ar·OH in both electronic states.