and

The heat capacities of the anhydrous lanthanide trichlorides from 5 to 350 K of Sommers and Westrum provide an excellent opportunity further to test the volumetric lattice heat-capacity approximation method. Schottky contributions in PrCI,, SmCl,, and EuCI, were calorimetric-ally derived using the volume-weighted interpolation between the lattice heat capacities of the La and Gd homologs. Previously qualitative agreement had been observed upon comparison of these calorimetrically derived Schottky contributions with those calculated from spectroscopic data obtained for Ln(III)-doped LaCI, crystals. Excellent accord between “spectroscopic ” and “calorimetric ” Schottky contributions is achieved by adjusting the Stark-level energies to represent those of the concentrated salts through extrapolation of the Ln(III)-doped LaCI, energies to stronger crystal fields either empirically or by means of estimated crystal-field parameters. These methods are described and the resulting energy levels are compared with the extant spectroscopic results for the concentrated trichlorides. In addition, new electronic-Raman-scattering determinations were made on PrCI, and SmCI, at I5 K and vibrational Raman lines are reported for SmCI, at 300 K. Deduced electronic energy levels for the ground and first excited [SL]J-manifolds are listed for both compounds. 1