Spectroscopic investigation of Mn2+, Pr3+ codoped KMgF3 under vacuum-ultraviolet excitation

Pr3+: KMgF3, Mn2+: KMgF3 and Pr3+,Mn2+: KMgF3 single crystals were grown by the Czochralski method and spectroscopically investigated in order to evaluate possible energy transfer processes between Pr3+ and Mn2+ after vacuum-ultraviolet excitation. These processes are of importance for the possible use of these materials as phosphors for discharge lamps based on the xenon discharge excitation. In Pr3+: KMgF3 besides the already known cascade emitting Pr3+ centre (S-1(0) -> I-1(6), P-3(0) -> 4f(2)) (Sokolska and Kuck 2001 Chem. Phys. 270 355), a second Pr3+ centre was clearly observed with 4f5d energy levels shifted to energies below the 1S0 level. For Mn2+: KMgF3 a broad emission band typical for Mn2+ with a maximum at 600 nm and the expected Mn2+ excitation bands in the visible (3d(5) -> 3d(5)) and vacuum ultraviolet (3d(5) -> 3d(4)4s) are observed. In the Pr, Mn: KMgF3 sample investigated, the expected energy transfer process [S-1(0)(Pr3+), (6)A(1)(Mn2+)] -> [(I-1(6), P-3(0,1,2))(Pr3+), ((4)A(1), E-4)(Mn2+)] could not be observed within the detection limit of the experimental setup. The efficiency for this energy transfer process was also calculated assuming dipole-dipole interaction and found to be < 5% for the sample investigated. The low concentration of the dopant ions and the small oscillator strength of the (6)A(1) -> ((4)A(1), E-4) transition of the Mn2+ acceptor ion is responsible for this low transfer efficiency.