On the Existence of “Sub-Bands” in the Luminescence Emission Spectrum of Manganese Activated Zinc Silicate*

Failure of the luminescence decay of manganese-activated zinc silicate to follow an exact exponential curve has been cited as evidence for the presence of two different emitting centers with different decay rates. However, the shapes of the spectral emission curves taken at different times after excitation are identical, showing that if two centers exist their emissions are the same. The luminescence emission of this phosphor has also been measured at 4°K and shows a single peak a few hundred angstroms wide. There is little observed change in the emission between 90°K and 4°K. The width of the room temperature emission is therefore the result of the temperature-broadening of an already broad band. No experimental evidence is found for bands predicted on the assumption that emission spectra are formed by the superposition of bands having the shape of Gauss error curves. Theoretical work on the shape of emission and absorption bands is reviewed and does not support the Gauss error curve theory.