The number of Ge I Ritz standards below 2000 Å has now been increased to approximately 100 lines with estimated uncertainties not exceeding 0.0009 Å, 68 of which have estimated uncertainties of 0.0003 Å. This extension is the end product of a systematic Fabry—Perot interferometric investigation which has extended the former interferometric region of 2019–4685 Å to 12 069 Å. Ninety-five interferometrically determined levels of Ge I are given, 72 of which have been improved by this effort.
Twenty-three lines of Ge II were also measured interferometrically leading to 20 improved energy levels of this spectrum and to estimated splittings of the ng2G (n = 5, 6, 7) terms. From the improved levels, twelve Ge II Ritz standards from 999 to 1966 Å have been calculated with estimated uncertainties not exceeding 0.0009 Å. An improved series limit of Ge II calculated from the nƒ2F and ng2G term series is 128 521.3 cm-l. This value made use of improved levels of this work and as yet unpublished data furnished by Shenstone.
VICTOR KAUFMAN and KENNETH L. ANDREW, "Germanium Vacuum Ultraviolet Ritz Standards," J. Opt. Soc. Am. 52, 1223-1236 (1962)