The Spectra of the Heavy Elements

Abstract

The spectra of the new heavy elements are characterized by great complexity similar to that well known for thorium and uranium. Consequently descriptions of the spectra to be adequate for term analyses and assignment of electron configurations must be quite extensive, containing complete, accurate wave-lengths and much other material. Since considerable effort and amounts of sample are required it will be some time before such descriptions are available. On the other hand it would be useful for spectrochemical analyses to have wave-lengths to 0.1A and intensities in a convenient spectral region, and this information has been collected for protactinium, neptunium, plutonium, and americium. Intensities for each line were obtained as the reciprocal of the limiting dilution at which it could be seen with the copper spark source, and therefore the same intensity scale is used for each element. Hence it could be observed that the spectrum of americium appears to stand in the same relation to those of the other heavy elements that the spectrum of europium does to those of the preceding rare earths, both elements containing relatively few lines of high average intensity. This suggests by analogy that Am I contains seven f electrons plus two others.