Revised and extended analysis of nine-times-ionized lanthanum (La X)

The lanthanum spectrum was photographed in the 80-1240 Angstrom region on a variety of vacuum spectrographs using triggered spark sources. The analysi s of nine-times ionized lanthanum (La X) has led to revision of four previo usly identified levels of the 5s5d configuration and established one new le vel S-1(0) of the 5s6s configuration, four levels of the 5s4f configuration , and nine out of twelve levels of the 5p4f configuration. The least square s fitted parametric (LSF) and Hartree-Fock (HF) calculations interpret the observed spectrum adequately. Fifty eight lines are now classified in La X, out of which forty five are new lines.