The spectrum of Nd3+:LaCl3

New measurements of the optical spectrum of trivalent neodymium in a hexagonal lanthanum chloride host have been made at 4 and 77 K at wavelengths down to 2500 Å (40 000 cm−1). Crystal quantum number assignments for new energy levels were derived from these results and for most of the earlier levels not already classified. A least-squares fit with a mean error of 8.1 cm−1 was carried out for 101 levels, using 20 adjustable parameters in a Hamiltonian containing operators for two- and three-particle electrostatic interactions; spin–orbit, spin–other-orbit and spin–spin magnetic interactions; two-particle pseudomagnetic configuration-mixing interactions; and single-particle crystal-field interactions.