CRYSTAL-FIELD AND ENERGY-LEVELS OF PR3+ CENTERS IN LINBO3

The polarized optical absorption and fluorescence of Pr3+ in LiNbO3 cr ystals have been exhaustively investigated at low temperature in order to obtain and characterize the crystal field energy levels for every multiplet of the system. Up to 51 energy levels have been determined f or this ion, and labelled by irreducible representations, E or A, assu ming C-3 local symmetry. These energy levels have been used to estimat e the crystal field (B-q(k) parameters) acting on the Pr3+ ion in this host crystal. As the optical spectra present additional structure owi ng to the presence of four Pr3+ centres, laser site selective spectros copy has been used to determine the Stark sublevels of the H-3(4) grou nd state for each particular centre. Thus, the slight variations of th e B-q(k) parameters from one centre to another have been investigated and interpreted in terms of different Li+-off centre positions for Pr3 + ions.