Long-range interatomic forces from spectroscopic data

Abstract

The method of using pre-dissociation data to determine interatomic forces suggested by Bernstein is applied to the case of HF where the Rydberg-Klein-Rees (R-K-R) curve of the molecule is known. Fitting the potential curve to c/r ⁶ at internuclear distances greater than 2r_e gives a value for c of 8·41 × 10^-59 erg cm⁶, in agreement with that calculated from the limiting curve of dissociation, 8·04 × 10^-59 erg cm⁶. A limitation of the Bernstein method is discussed. The long-range interatomic forces in the halogens are also studied using R-K-R data and certain anomalies in the results pointed out.