ABSTRACT
Although the equilibrium structure, as dened by the Born-Oppenheimer approximation [1], can, in principle, be extracted from purely experimental information, the procedure is quite arduous. In particular, one needs to know the rotational constants in each and every vibrationally excited state that corresponds to a fundamental vibration-a task that becomes progressively more unwieldy as the molecular size increases-and for not just the molecule of interest but also several isotopologues.
