Mass Ratio of Hydrogen and Deuterium from Band Spectra

Abstract

The size of the several corrections to the observed, apparent $B_e$ constants of the usual rotational energy expression in order to obtain "true" $B_e$ values is calculated for some diatomic hydride and deuteride molecules. It is shown that the corrections arising from the uncoupling terms due to the interaction of certain electronic levels (Van Vleck, Mulliken) and from the inclusion of the interactions between nuclear and electronic motions (Kronig) are by far the most important for the molecules considered. The calculations also show that, assuming 1.0081 to be the mass of the hydrogen atom, the mass of deuterium has to be greater than the 2.01423 value given in a number of recent articles. A value close to Aston's latest, 2.0148, is indicated.