Quantum Efficiency Measurements on Several Phosphors under Excitation in the Extreme Ultraviolet

The response of several inorganic phosphors to radiation in the wavelength range of 275 A to 1715 A has been explored. The chief apparatus employed was a grazing incidence vacuum grating monochromator, using both a hydrogen arc source and an air spark source. Sodium salicylate, whose quantum efficiency is reportedly almost independent of wavelength, was used as a reference phosphor; therefore, excitation spectra are given in terms of quantum efficiency relative to sodium salicylate. Excitation spectra for CaMg(SiO3)2:Ti, CaSiO3:Mn:Pb and 3Ca3(PO4)2·Ca(F,Cl)2:Mn:Sb are limited to a range from 1026 A to 1640 A, and all show a simple decline with decreasing wavelength. CaWO4:Pb and Mg2WO5:[W] show a minimum in quantum efficiency at about 1000 A; whereas Zn3(PO4)2:Mn has a minimum at about 700 A. All of the latter three phosphors exhibit marked increases in quantum efficiency with decreasing wavelength in the extreme ultraviolet.