UV Phosphors for Highly Efficient Excitation by VUV

Abstract

We have developed ultraviolet (UV) phosphors of a new type that is suitable for excitation by the vacuum ultraviolet (VUV) light generated by Xe discharge. The phosphors contain gadolinium (Gd) and praseodymium (Pr) in yttrium fluoride (YF₃). The YF₃ : Gd, Pr phosphor exhibits a strong emission line at 311 nm, and a weak emission band around 407 nm. The photoemission intensity of the 311-nm line is about 10 times as strong as for conventional UV phosphors. These emissions are effectively stimulated under excitation in the range from 150 to 200 nm, which corresponds to the f-d transition in Pr³⁺ ions. These results suggest that the strong emission of UV is due to a highly efficient transfer of energy from Pr³⁺ to Gd³⁺ ions. The process of energy transfer between these ions is discussed in terms of the experimental results of this and other studies.