Knowledge Bank

A new technique, Stimulated Emission Pumping (SEP), has been used to examine the rotation-vibration structure of the $X~1A1$ state of formaldehyde at energies up to $104$ $cm-1$. A complete set of 21 $Xij$ anharmonicity constants has been determined from a, b, and c-type $A~\to X~$ transitions from the $41$ level and from numerous Coriolis and Fermi perturbations. B and C rotational constants as well as dipole moments are observed for many highly excited levels of the $X~$ state. Coriolis perturbations are extremely numerous at high vibrational excitation and the SEP technique makes their analysts trivial. Although nonrotating vibrational levels exhibit large and systematic structural differences, at J $\sim $ 10 and K $\sim$ 3 Coriolis mixing minimizes these differences so that all properties become locally averaged. This has important implications about the possibility of level-specific chemistry.