Estimation of the dissociation energy of weakly-bound molecules from spectroscopic data

Expressions for the dissociation energy of the Morse potential and the Lennard-Jones (2n,n) potential are derived in terms of low-order mechanical constants of diatomic molecules. These expressions are related to a more general series expansion of the potential, and a new expression for the dissociation energy of a weakly bound diatomic is derived. This expression contains Be’αe’ and the power of R−1 which leads a long-range expansion of the potential. The expression is accurate to a few percent when compared to reliable experimental values and should be of value when only a limited number of spectral constants can be obtained from experiment.