High spins weak-field limit

The zero-field spin Hamiltonian parameters, D and E, are assumed to be distributed according to a normal distribution with standard deviations oD and aE, which we will express as a percentage of the average values (D) and (E). -Strain itself is not expected to be of significance, because the shape of high-spin spectra in the weak-field limit is dominated by the zero-field interaction. 

Table 21.9 A shorthand table of microstates for a configuration only a high-spin case (weak field limit) is considered, and each electron has = +. The microstates are grouped so as to show the derivation of the and P terms. Table 21.7 provides the complete table of microstates for a d ion.

Electronic spectroscopy is a complicated topic and we shall restrict our discussion to high-spin complexes. This corresponds to the weak field limit. We begin with the electronic absorption spectrum of an octahedral (fi ion, exemplified by [Ti(OH2)6] ". The spectrum of [Ti(OH2)e] + (Fig. 20.4) exhibits one broad band. However, close inspection shows the presence of a shoulder indicating that the absorption is actually two closely spaced bands (see below). The term symbol for the ground state of Ti (d, one electron with L = 2, S = 5 ) is D. In an octahedral field, this is split into Fig. 20.18 Energy level diagram for a t/ ion in an octahedral field. 

Figure 8. Schematic energy level diagrams for high-spin Fe " in the weak magnetic field limit where hv zero field splitting, (a) EjD (Compare with Figure 7a). (b) EjD = 1/3 (Compare with Figure 7b). The effective g values are indicated.

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