Quantum mechanical study of the vibrational–rotational structure of [O2(1Δg)]2. Part II

Abstract

The methodology used in the calculation of the rovibrational levels of the singlet ground state of [O₂(³Σ_g^-)]₂ has been extended to the treatment of the rovibrational levels of the four singlet states of [O₂(¹Δ_g)]₂. Two cases have been considered. The first one is when the two monomers are in their ground vibrational level (v=0) and the second case is when one monomer is in the first excited vibrational level (v=1) while the other remains in its ground vibrational level (v=0). Due to different symmetry relations in the permutation-inversion group, more levels are populated in the second case. The dissociation energy (D₀^′=23 cm^-1) is lower than the predicted value of Long and Ewing (D₀^′=41 cm^-1) while the difference between the dissociation energy of the ground and excited state, D₀^″-D₀^′, is in good agreement with the recent estimation of Campargue etal. Using semiempirical potential energy surfaces, we found 27 bound vibrational levels (J=0) for O₂(¹Δ_g)_(v=0)+O₂(¹Δ_g)_(v=0) and 37 bound levels for O₂(¹Δ_g)_(v=0)+O₂(¹Δ_g)_(v=1).