On the structure of the arc spectrum of gold

Abstract

The first successful attempt to find series relationships among wave-lengths of the gold arc spectrum was that made by Thorsen in 1923. In his paper he classified two sets of wave-lengths into a sharp and diffuse subordinate doublet series, the first pair of the sharp series providing the first pair of the corresponding principal doublet series. In a communication by us a year ago some absorption experiments were described that were carried out with the normal vapour of gold in the quartz and fluorite spectral regions. In this communication it was shown that we were able to extend this series so as to include the second pair as well. In addition, two other interesting features of the spectral structure were pointed out that at the time were not completely understood. The first of these was concerned with the existence of a deep metastable inverted doublet D term, and the second with a pair of terms that were characterized by features similar to those of doublet terms of the P type. This pair did not seem to belong, however, to the regular series of doublet P terms. In the communication referred to we also pointed out that our term scheme did not permit us to classify a number of strong lines that were known to belong to the gold arc spectrum, and that included many of the wave-lengths found to be absorbed by Miss Buffam and Mr. H. J. C. Ireton in experiments on the underwater spark spectrum of gold. To account in general way for many of these wave-lengths we suggested that they might possibly be found to belong to a quartet or to a sextet system, the features of which we were not at the time able to develop. Recently, through the brilliant work of Pauli, Heisenberg and Hund on the interpretation of spectra, we have been furnished with a means predicting with considerable accuracy the structure of any spectrum. By this theory, with some modifications and extensions, we can now predict the structure of the gold arc spectrum, and as a consequence are able to carry out a more systematic investigation of its features. The significance of the two unusual features found by us in our earlier work and mentioned above is now more clearly understood. We shall proceed to explain these features and to develop the structure of the spectrum more fully in the discussion following in Sections IV and V.