Ground State D2 Dissociation Energy from the Near-dissociation Behavior of Rotational Level Spacings

Abstract

A method of determining the dissociation energy of a diatomic molecule from the rotational term value(s)of a single vibrational level lying near dissociation is derived and tested. It is based on expressions relating the characteristic near-dissociation behavior of the rotational constants Bv, Dv, Hv,… etc., to the asymptotically dominant inverse power contribution to the long range intermolecular potential. Application of this procedure to data for ground state D2 yields a dissociation energy of D0 = 36 748.88(±0.3)cm−1, in essentially exact agreement with the value Herzberg determined from the onset of continuum absorption in the vacuum u.v., 36 748.9(±0.4) cm−1. This agreement between results obtained from completely different observables appears to confirm the existence of a small discrepancy between experiment and the most recent theoretical nonadiabatic dissociation energy of Kolos and Wolniewicz, 36 748.2 cm−1.