Ultraviolet emissions from Gd3+ ions excited by energy transfer from Ho3+ ions
نویسندگان
چکیده
ions are populatedbyan energy transfer (ET) process fromS7/2 (Gd)+( P1, L8, M10) (Ho)PJ (Gd)+ I8 (Ho). A four-photon ET UC process was confirmed by the dependence of the P7/2 level emission intensity on the pumping power.We found that the intensity of the UC emissions increasedwith Gd ion concentration and peaked at 8 mol%, then starts to decrease until the Gd ion concentration reached 70 mol%. The variation in the UV emission intensity is the result of the competition between the ET process and concentration quenching effect. Theoretical calculations based on steady-state equations validated the proposed UC mechanisms. & 2010 Elsevier B.V. All rights reserved.
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