Crystal field theory activation energy

The use of crystal field theory makes it possible to present a more detailed classification than simply inert and labile. The approach depends on a comparison of the CFSE of a coordination compound and of its activated complex (recall that activated complex refers to a configuration of reactant molecules such that the reaction can proceed without further addition of energy). 

Most minerals fall into the class of insulator phosphors. The characteristics of the luminescence are usually defined by the electronic structure of an activator ion as modified by the crystal field of the host crystal structure. Although some energy transfer takes place between nearby ions, appearing as the phenomena of co-activation, luminescence poisons, and activator pair interactions, the overall luminescence process is localized in a "luminescent center" which is typically 2 to 3 nm in radius. From a perspective of band theory, luminescent centers behave as localized states within the forbidden energy gap. 

Three IR bands at 1370, 1260, and 500 cm-1 are also seen in Fig. 2.5. These energies are in the gap between the Raman mode of pure r-PA and are predicted by theory for the photoinduced solitons. The band near 500 cm-1 is attributed to the pinned soliton-antisoliton pair. The IR vibrational bands are also observed at 900, 1270, and 1370 cm-1 in the doped crystals. The band at 1270 cm-1 is rather weak. One possible explanation of the existence of the IR bands is that the coupling of the n electrons with the C-atom vibration along the chain increases the dipole-moment of the C vibrations making them infra-red active. The soliton vibrations in the Coulomb field of the impurity can also give rise to the infra-red active modes [14], A more detailed discussion of these bands is given in [6],... 

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