The spectrum of gold from several different light sources has been investigated. Precision measurements have yielded new data on wavelengths and energy levels in Au I, Au II, and Au III. The spectrum from a high-intensity hollow-cathode lamp with a secondary discharge from an extra pair of Electrodes to reduce line broadening and self-reversal was studied with a high-resolution Czerny-Turner spectrograph from 2600 to 9600 Å. This study yielded an accurate line list along with information on the hyperfine structure of levels in Au I and the first observations of hyperfine splittings in Au II. Few lines from levels with high orbital angular momentum were seen, providing information on the type of excitation in this kind of lamp. Autoionization in gold is reported for the first time, and broad lines 1–5 cm-1 wide were classified as arising from two autoionizing levels in Au I. The vacuum-ultraviolet spectrum from a condensed spark was studied, and new lines were found in Au II and Au III.
JAMES C. EHRHARDT and SUMNER P. DAVIS, "Precision Wavelengths and Energy Levels in Gold," J. Opt. Soc. Am. 61, 1342-1349 (1971)