UV radiation, 304 wavelengths

This is considerably below the UV radiation wavelengths from the sun and artificial lights. 

What this means is that these UV-radiation wavelengths will excite the phosphor which then emits visible green light. When the phosphor is prefired in air, the resulting phosphor does not respond to UV excitation. However, cathode-ray excitation (an electron-beam like a television tube) produces the same green emission. Emission occurs from Mn centers in the spinel structure. These centers are not Intrinsic defects as such since the divalent manganese is able to substitute directly at the Mg sites in the spinel structure. The only difference is the radius of the two cations at the tetrahedral site. It is because of this difference that increasing the Mn concentration leads to less efficient, i.e.- "duller , phosphors. 

At this point the reader may be cimous about the mechanism by which UV radiation is able to photocure a composition containing metal particles. Clearly the metal particles are opaque to UV radiation wavelengths. This subject is of considerable practical interest, as metal-containing pastes, and indeed, other photoactive pastes containing opaque materials can be hardened when exposed to UV radiation. 

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