Oxygen — metal charge transfer transitions

Table 9.4. Oxygen —> metal charge transfer transitions in minerals at high pressures and temperatures... 

The electronic spectra of a variety of transition metal-bearing oxide and silicate minerals have been measured at high pressures and/or elevated temperatures. Trends for absorption bands originating from crystal field (CF), metal-metal intervalence charge transfer (IVCT) and oxygen —> metal charge transfer (OMCT) transitions are summarized in tables 9.2,9.3 and 9.4, respectively. 

Fig. 3-1. Band assignment for the diffuse reflectance spectrum of a goethite. Note that one band eould not be assigned. EPT electron pair transition OMCT oxygen-metal charge transfer. From Seheinost et al., 1999 with permission.

Problem 12.11 The octahedral complexes of transition metals show, in general, weak colours, in comparison with the permanganate ion, for instance. In the first case, the relevant transition is t2g e, whereas in the latter it is a charge transfer transition between the metal and the oxygen atoms. Justify the different transition probabilities. 

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