Recordings of the spectra of argon and krypton from microwave-excited electrodeless sources have led to observation of a considerable number of previously unreported lines. These new observations comprise 30 lines of argon between 14 000 and 25 000 A, and 10 lines of krypton between 20 000 and 25 000 A. All are accounted for as transitions between known energy levels.
E. PAUL, JR. and CURTIS J. HUMPHREYS, "Newly Observed Lines of Argon I and Krypton I in the Lead-Sulfide Region," J. Opt. Soc. Am. 49, 1186-1187 (1959)