Fig. 6. The simplified energy level splitting of the low-lying states for (a) a lanthanide–radical–lanthanide (Ln–rad–Ln) spin system with strong antiferromagnetic Ln–rad coupling; and (b) a lanthanide–radical (Ln–rad) dimer with weak ferromagnetic coupling. Only the positive half (spin up) of the degenerated states are depicted for clarity, as the other half is simply with all opposite orientations. The corresponding Zeeman diagrams are also presented. The large difference of the final Δ (grey and green arrows, respectively) compared with the original single ion ΔSIM should be particularly noted.
