Acknowledgments

adjacent o an ant imony-oxygen pair, and on a Ca (II) site adjacent o a chlorine ion in those phosphors con-taining chlorine. In the most commercial ly important phosphor of the group, CW, we find that between 60 and 70 % of the manganese is present as Mn ( I) , be-tween 5 and 10 % as Mn ( I I) , between 1 and 5 % as Mn(Sb) , and between 20 and 30 % as Mn(C1). The phosphor functions in the following manner in the fluorescent lamp. The ant imony ions absorb the 2537A radiat ion and either fluoresce or transfer energy to Mn + ~ ions. Most of the Mn +2 fluorescence that results is due to Mn ( I) , with smaller components due to Mn(C1) and Mn ( I I) , and a very small component due to Mn(Sb). The fluorescence nvelope of Mn ( I) in CW is at longer wavelengths than Mn ( I) in calcium fluorophosphate. This Mn (I) envelope shift is pr imar i ly responsible for the color shift observed in the CW phosphor elative to calcium fluorophosphate. The shift is not due to a redistr ibution between the Ca ( I) and Ca ( I I) sites due to the introduction of Sb, Cd, and C1 as Johnson proposed (7), nor due to the formation of new Mn(C1) centers as Butler and Jerome (5) pro-posed, although the formation of Mn(C1) centers does occur to some degree and does cause a slight addit ional wavelength shift to the composite Mn + ~ fluorescence envelope