Photoluminescence measurements of polyphosphate phosphors LnP(3)O(9): Tb3+ (Ln = Y, Gd) indicated that the phosphors exhibited bright-green emission at 544 nm under 147 nm excitation. Host absorption bands in region from 120 to 174 nm were observed which showed that the green emission of Tb3+ ion in LnP(3)O(9) (Ln = Y, Gd) under vacuum ultraviolet excitation was due to the energy transfer from the hosts. In addition, the observed Tb3+ f-d transitions at 212, 249, and 260 nm were well consistent with the values calculated from the Dorenbos' expression. (c) 2007 The Electrochemical Society.