The spectrum of photoexcited Nd3+ ions in LaCl3

Nine new levels of the 4f 3 configuration of trivalent neodymium in lanthanum chloride have been identified through absorption experiments on the photoexcited ions. Transitions from the ground state to the μ=5/2 levels are forbidden by the selection rules; by populating the metastable levels (μ=1/2 and 3/2), absorption transitions to the μ=5/2 levels are observed. A least squares fit has been carried out for the 127 known levels of Nd3+:LaCl3 using a Hamiltonian with 20 adjustable parameters.