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 ( 1S0 → 1I6, 3P0 → 4f2) (Sok?lska and K?ck 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( 3d5 → 3d5) and vacuum ultraviolet 3d5 → 3d54s) are observed. In the Pr,Mn:KMgF3 sample investigated, the expected energy transfer process [1S0(Pr3+), 6A1(Mn2+)] → [1I6, 3P0,1,2)(P3+) (4A1, 4E)(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 6A1 → (4A1,4E) transition of the Mn2+ acceptor ion is responsible for this low transfer efficiency