SPECTROSCOPY AND CRYSTAL-FIELD ANALYSIS FOR ND(3+) IN GDLIF(4)

Spectroscopic results are presented and crystal-field parameters are d etermined for Nd3+ in the new laser crystal GdLiF4. We take the unusua l approach of expanding the crystal field in terms of operators transf orming as irreducible representations of the T(d) group. This allows u s to directly interpret the parameters in terms of a point-charge stru ctural model. The traditional B(kq) parameters are then obtained via a linear transformation. Their values are nearly identical to those for Nd3+ in YLiF4. The slightly weaker crystal field for GdLiF4 suggests a dilation of the lattice caused by the larger ionic size of Gd3+ as c ompared to Y3+.