Electronic Excitation Dynamics and Energy Transfer in Lithium—Gadolinium Borates Doped by Rare Earths

摘要

This paper reports on luminescence studies of lithium borate Li_6Gd(BO_3)_3doped with Eu~(3+)andCe~(3+)and Li6Eu(BO_3)_3crystals upon selective excitation by synchronous radiation in the pump energy region3.7-27 eV at temperatures of 10 and 290 K. The effective energy transfer between the rare-earth ions Gd~(3+)iuCe~(3+)and Gd~(3+)iuEu~(3+) is found to operate by the resonant mechanism, as well through electron—holerecombination. A study is made of the fast decay kinetics of the Ce~(3+)-center activator luminescence under intra-center photoexcitation and excitation in the interband transition region. The mechanisms underlying lumines-cence excitation and radiative relaxation of electron states of rare-earth ions are analyzed and energy transferprocesses active in these crystals are discussed.