Derivation of spectroscopic constants of a diatomic molecule from the experimental data on highly excited vibration-rotational states: application to the HCl molecule

Abstract

The relations between spectroscopic constants of the series for the energies of vibration-rotational states of a diatomic molecule constructed in references 1 and 2 and the constants Y<SUB>ij</SUB> of the Dunham series are reported. The precise experimental data on the energy levels of the molecular HCl comprising practically all the discrete vibration-rotational spectrum in the ground electronic state were treated. It has been proved that the series constructed in references 1 and 2 possesses much better convergence and predicting ability than the Dunham series and enables one to derive the Y<SUB>ij</SUB> constants from the adequate treatment of the whole set of experimental data concerning to the discrete spectrum of a molecule.