text: Another example is [Co(HO)]. Note that the ligand is the same as the last example. Here the cobalt ion has the oxidation state of +2, and it is a d ion. From the high-spin (left) side of the d Tanabe–Sugano diagram,  the ground state is T(F), and the spin multiplicity is a quartet. The diagram shows that there are three quartet excited states: T, A, and T(P). From the diagram one can predict that there are three spin-allowed transitions. However, the spectrum of [Co(HO)] does not show three distinct peaks that correspond to the three predicted excited states. Instead, the spectrum has a broad peak (spectrum shown below). Based on the T–S diagram, the lowest energy transition is T to T, which is seen in the near IR and is not observed in the visible spectrum. The main peak is the energy transition T(F) to T(P), and the slightly higher energy transition (the shoulder) is predicted to be T to A. The small energy difference leads to the overlap of the two peaks, which explains the broad peak observed in the visible spectrum.