VUV emission of rare-earth ions doped into fluoride crystals

VUV emission of LiY1-xErxF4 single crystals (x = 0.05, 0.2, 1) has been studied in an extended range of excitation energy and in a wide temperature range. It was found that strong concentration quenching occurs in highly doped crystals leading to nanosecond decay for both spin-allowed and spin-forbidden 5d-4f transitions in Er3+. The impact mechanism of the energy transfer from the matrix to Er3+ ions results in relatively high quantum yield of Er3+ d-f luminescence in such crystals at high-energy excitation. It was shown that the scheme of intermediate electron-phonon coupling should be used for the description of bandwidth temperature broadening for d-f luminescence. (C) 2000 Elsevier Science B.V. All rights reserved.