Book Description

This paper lists the most prominent spectrum lines of the elements from protactinium to americium. In most cases, the spectra were made available because of the necessity of conducting spectrochemical analyses on a number of samples for impurities. Because of limitations of sample size, it was not feasible to perform the analyses with the aid of chemical or physical separations, and so the spectrum of the major constituent was always present. It would be of considerable interest to provide descriptions of the spectra which would be adequate for term analyses leading to energy levels and electron configurations, not only for the spectroscopic interest but also for the assistance they might provide in the correlation of chemical properties of these elements. However, the amounts of labor and sample required for such descriptions are quite formidable, as is evidenced by the fact that the spectra of thorium and uranium are still incompletely analyzed in spite of their having been available in unlimited quantities for many years. To be adequate for a term analysis, the wavelengths must be measured to the third decimal place for as many lines as can be observed over the most extensive wavelength range accessible; Zeeman patterns must be provided; and a temperature or excitation variation must be provided in order to distinguish the various stages of ionization and low levels from high levels. On the other hand, for purposes of identification, it is sufficient to have measurements of the strongest lines of each element, accurate to the first decimal place, covering a representative wavelength region that is convenient for analysis. Since it will probably be some time before data of much value for term analyses are accumulated, the following information was collected for whatever usefulness it might have in spectrochemical analyses.