Resonance exchange integral, dependence

Fig. 8.8. The dependence of resonance exchange integral on doping parameter...

Excitations similar to giant resonances are observed for much deeper-shell excitation, and are more aptly named shape resonances, because the spatial overlap between the initial and final states is less complete than for giant resonances. An example is 3d — f in Ba, which is similar in character, but not identical, to Ad —> / in the same element in particular, the smaller spatial overlap means that the exchange integral has a less dramatic influence on the spectrum, which is why, when studying solids (see chapter 11), deep shell excitation is preferred if the resonance is to be used as a probe of final state density in this way, one avoids most of the term dependence. 

The integral is the spectral overlap integral of the donor emission f (v) with the acceptor absorption profile f (v) for resonance condition. F(R) summarizes the essential mechanisms, like the Dexter (1953) exchange or the Forster (1951) multipole mechanism with their specific R distance dependences. 

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