Recombination processes related to Eu2+ energy level position in ionic CaxCd1-xF2 crystals |
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Authors: | Krzysztof Świąk Marek Godlewski Zbigniew Kaliński |
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Institution: | Institute of Physics, Polish Academy of Sciences , PL 02-668 Warsaw, Al. Lotników 32/46, Poland |
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Abstract: | Abstract We study efficiency of autoionization and recombination transitions for europium in CaxCd1-xF2 host lattice depending on the energy level position of Eu2+ 4f65d1(e) excited states in respect to the conduction band (CB) states. From photoluminescence (PL) and absorption measurements we conclude that for x in the range of 1 - 0.65 thermalization within the 4f65d1(e) multiplet is faster than the appropriate autoionization transition. For x > 0.65, when all the excited 4f65d1 states are degenerate with the CB autoionization is immediate, Eu2+ intra-ion emission is quenched and a new Eu-related emission appears, which we tentatively assign to a radiative capture emission of hot nonequilibrium electrons. |
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