[bmu123]

Assuming that, for both electronic states of O₂, the molecule behaves as a harmonic oscillator, find ω_e, the vibrational wavenumber, for the X and B states of O₂.  Then calculate the wavenumber of the (2,2) band, and the difference in electronic energy (minimum to minimum, ΔT_e) between these two electronic
states.

So I'm given a Deslandres table and have worked out ω_e for each state, and found that the wavenumber of the (2,2) band = 47603.1 cm^-1. What equation do I use to work out ΔT_e? I can only find ones for anharmonic oscillators in my notes

[mjc123]

What is the energy of a vibronic state of a harmonic oscillator? Come on, we've done this in another thread!
(Alternatively, use your anharmonic equation and set the anharmonicity constant to zero.)