Spectra of Argon in the Extreme Ultraviolet

A simple method for the excitation of spectra of higher stages of ionization of rare gases is described. Applied to argon, the method has yielded spectra of all stages of ionization from A III to A IX. Classified lines in the extreme ultraviolet and term tables for the ions V to IX are given. Some minor additions and corrections to previous analyses of Cl V and Cl VI are pointed out.