INTERPRETATION OF THE OPTICAL-ABSORPTION SPECTRUM AND OF THE PARAMAGNETIC-SUSCEPTIBILITY OF NEODYMIUM OXYSULFIDE

The optical absorption spectrum of neodymium oxisulfide has been fitted; the mean quadratic deviation is 10.7 cm-1 for 65 assigned Stark levels with a Hamiltonian involving 14 free-ion parameters and six C3v crystal field parameters. The paramagnetic susceptibilities (mean, parallel and perpendicular to the trigonal axis in the structure) have been measured from 4.2 K to about 200 K, and compared with the values derived from the wave vectors and energies of the 18 lowest Kramers doublets through the application of the Van Vleck formula. We also give the values of the spin-orbit coupling constant ζ versus the Slater parameter F2 for six compounds spanning the whole of the neodymium nephelautic series.