The emission-spectra (excited by short ultraviolet) of two crystalline forms of the zinc-silicate: Mn phosphor have been recorded photographically. A number of operating temperatures were used. The rhombohedral form, normally green-emitting, develops a yellow band at elevated temperatures. The hightemperature-quenched form, normally yellow-emitting, develops two green bands at lowered operating temperatures. Analysis indicates the possibility that the same bands are potentially present in both forms, but the effect of the different configurations is to emphasize different bands, especially with regard to their response to changes in temperature of operation. In addition to the “band” structure, “fine” structure was found for both forms at the lowest operating temperature (-196°C).
R. E. SHRADER, "Temperature-Dependent Structure of the Emission Spectra of Two Crystalline Forms of the Zinc Silicate: Mn Phosphor," J. Opt. Soc. Am. 39, 699-700 (1949)