Energy levels of unpaired electrons

The splitting of the energy levels of unpaired electrons by means of a magnetic field is referred to as the Zeeman effect. The energy of an unpaired electron in a magnetic field is given by... 

Table 10.3 Electronic energy levels of some common molecules or atoms with unpaired...

S0, S], S2,. .. represent so-called singlet states in which all the electrons have paired spins, and T1( T2,. .. represent triplet states in which two electrons have unpaired spins. The energy levels of both ground (S0) and activated states (Sj, S2,. ..) are subdivided into vibrational and rotational energy levels. The vibrational energy levels are shown in Figure 11.2. Differences in rotational levels are very small and can be ignored for the present discussion. 

Figure 1.2 Energy levels of an unpaired electron in a magnetic field interacting with a spin-1/2 nucleus. The arrows show two allowed transitions.

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