Luminescence VUV spectroscopy of cerium-and europium-doped lithium borate crystals

Abstract

The paper reports on a study of the luminescence of lithium borate crystals (Li 6 Gd(BO 3 ) 3 doped by Eu 3+ and Ce 3+ ions, Li 5.7 Mg 0.15 Gd(BO 3 ) 3 : Eu, and Li 6 Eu(BO 3 ) 3 ) initiated by selective excitation by synchrotron radiation at excitation energies of 3.7–27 eV at 10 and 290 K. Efficient energy transfer between the rare-earth ions Gd 3+ → Ce 3+ and Gd 3+ → Eu 3+ was found to proceed by the resonance mechanism, as well as by electron-hole recombination. Fast decay kinetics of luminescence of the Ce 3+ activator centers was studied under intracenter photoexcitation and excitation in the interband transition region. The mechanisms involved in luminescence excitation and radiative relaxation of electronic states of rare-earth ions are analyzed, and the energy transfer processes operating in these crystals are discussed.