Improved parameterization for combined isotopomer analysis of diatomic spectra and its application to HF and DF

A new way of representing vibration-rotation term values for multiple isoto pomers of a given electronic state of a diatomic molecule is presented whic h resolves problems associated with the way the conventional combined isoto pomer expansion represents the atomic mass-dependent JWKB and Born-Oppenhei mer breakdown correction terms. Its application to infrared and microwave d ata for HF and DF yields new Dunham expansion coefficients and Born-Oppenhe imer breakdown correction terms for this species. This procedure is impleme nted in a generally available computer program for fitting to various types of data involving one or several electronic states of multiple isotopomers of a diatomic molecule. (C) 1999 Academic Press.