Proposed Standard Wavelengths in the Vacuum Ultraviolet Spectra of Ge, Ne, C, Hg, and N†

The spectrum emitted from a germanium hollow-cathode discharge was photographed at high dispersion in the third order of a 21-ft concave grating spectrograph. Emission lines of Ge II, Ne II, Hg I, Hg II, C I, and N I were measured against Ge I Ritz standards in the regions 1550–2041 Å and 2325–3060 Å. The Ge I Ritz standards were investigated as to their suitability, and it was found that 56 lines in the region 1650–2041 Å may be used with confidence to ±0.0004 Å. Fifty-eight interpolated lines of Ne, Hg, C, N, and Ge may be used as auxiliary standards to ±0.001 Å in the region 1550–2041 Å. The interpolated measurements in the region 2325–3030 Å provide 74 lines with a standard error of ±0.002 Å which also may be useful. The present investigation of the Ge ii spectrum has provided revised energies for 15 levels. From these levels and 12 additional levels from the recent work of Kaufman and Andrew, the wavelengths of 22 lines in the region 837–1602 Å have been calculated with an estimated uncertainty of ±0.0004 to ±0.0018 Å.