The Vanadate Complex VO

The vanadate complex occurs mainly as a tetrahedral unit. Luminescence measure-complex. As mentioned above the VO  

In our laboratory the luminescence of the vanadate group has been studied in a large number of host lattices in order to investigate the nature of the electronic transitions in the vanadate group 

The emission of the vanadate group in solids may be situated in every part of the visible spectrum dependent on the nature of the host lattice. In YVO4, for example, the maximum of the emission band peaks at about 420 nm, but in Mg3(VO4)2 at about 570 nm. Usually the emission bands are very broad (some 4000 cm ) without vibrational structure down to liquid helium temperature. We are aware of only one exception, viz. the emission of silica containing V (and Al for charge compensation) (Fig. 9). 

In our opinion this shows that the thermal quenching temperature of the luminescence of the closed-shell complexes depends more strongly on the energy difference between the parabolae than on their offset ). In fact only the colourless complexes are able to show luminescence of any importance. 

In Fig. 10 we have given some excitation spectra of the VO luminescence. In concentrated systems they peak in the region between 28000 and 32000 cm , followed by a second band around 35000 cm L In diluted systems the latter band dominates and there is only a shoulder at lower energy. 

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