Vibrational Energy Levels for Sulfur Dioxide Isotopologues

For five isotopologues of the SO₂ molecule: ³²S¹⁶O₂, ³⁴S¹⁶O₂, ³³S¹⁶O₂, ³²S¹⁸O₂, and ³²S¹⁶O¹⁸O, parameters of the effective vibrational Hamiltonian are derived from fitting to the available experimental data, as well as using the basic relations of the isotope substitution theory. Vibrational constants obtained from the fit reproduce the experimental vibrational energy levels within 0.025 cm^–1 for symmetric isotopologues. The obtained vibrational energy levels are compared with the variational calculation, and the quantum numbers for 93 vibrational states are corrected.