Cross Relaxation and Energy Transfer in Cs2NaSmxEuyY1-x-yCl6

T. Luxbacher, H.P. Fritzer Institut für Physikalische und Theoretische Chemie, Technische Universität Graz, 8010 Graz, Austria and C.D. Flint Laser Laboratory, Department of Chemistry, Birkbeck College, 29, Gordon Square, London WC1H 0PP, U.K.

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Luminescence decay curves have been measured for the Sm3+ 4G5/2 → 6H7/2 emission in the cubic crystal Cs2NaSmxEuyY1-x-yCl6 (x = 0.005 to x = 1, y = 0 to y = 0.99) over the temperature range 10 K to 300 K using pulsed laser excitation into the 4G5/2 state of Sm3+. The luminescence from the 4G5/2 state of Sm3+ is strongly quenched by both, cross relaxation to nearest-neighbour Sm3+ ions and energy transfer to the 5D0 state of Eu3+. We interpret these processes in terms of a recently developed discrete shell model. The dependence of energy transfer from the Sm3+ donor ion to Eu3+ acceptor ions on y is readily studied and modelled. The temperature dependence shows that the cross relaxation occurs mainly by electric dipole vibronic-electric dipole vibronic interaction while in the energy-transfer process magnetic dipole allowed electronic contributions are also involved.

DOI: 10.12693/APhysPolA.90.161 PACS numbers: 33.5.-j, 34.50.Gb, 78.55.Hx