Analysis of Rotational–Vibrational Transition Frequencies of the HCl Molecule and Its RKR Potentials in the Ground Electronic State

The consistency of all data that have been published to date on the rovibrational line centers of the hydrogen chloride molecule HCl is analyzed. It was revealed that a number of corrections are needed because of systematic inaccuracies in the line center determination. A simultaneous fit of rovibrational transition frequencies was performed in the region from 7.4 to 18075 cm –1 . The isotopically independent spectroscopic parameters for calculating rovibrational energy levels in the ground electronic state are determined. The calculated line centers are compared with the HITRAN data. The obtained spectroscopic parameters are used to calculate the turning points ( r min and r max ) of RKR-potentials of HCl isotopologues. The use of experimental data, including the highest vibrational state with V max = 8 that lies approximately at half the potential well depth allowed the pointwise potentials to be calculated up to V max = 20.