The Third Spectrum of Gold (Au III)

The spark spectrum of gold has been photographed in a helium atmosphere from 500 A to 6600 A. About 500 lines have been assigned to the third spectrum, Au III, and separated from those belonging to different stages of ionization, by observation of the polarity of the lines. Sixty two levels have been found: 17 even levels, arising from the 5d ⁹ and 5d ⁸ 6s configurations; and 45 odd levels, belonging to the 5d ⁸ 6p and 5d ⁷ 6s 6p configurations. All of the expected levels from the configurations 5d ⁹, 5d ⁸ 6s and 5d ⁸ 6p have been identified except for the very high terms based on the 5d ⁸(¹S) core of Au IV. With these levels it was possible to classify 256 lines.