Site-selective spectroscopy of SrF2:0.05%Pr3+ crystals co-doped with u
p to 1% LaF3 reveals just one mixed La3+-P3+ centre, whose energy leve
ls are reported. Pseudo-quadrupole splittings of the Pr3+ hyperfine le
vels for this centre were determined using optically detected nuclear
magnetic resonance (ODNMR) techniques. (C) 1998 Elsevier Science B.V.
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