9 research outputs found
Recommended from our members
Measurement and interpretation of plutonium spectra
The atomic spectroscopic data available for plutonium are among the rickest of any in the periodic system. They include high-resolution grating and Fourier-transform spectra as well as extensive Zeeman and isotope-shift studies. We summarize the present status of the term analysis and cite the configurations that have been identified. A least-squares adjustment of a parametric Hamiltonian for configurations of both Pu I and Pu II has shown that almost all of the expected low levels are now known. The use of a model Hamiltonian applicable to both lanthanide and actinide atomic species has been applied to the low configurations of Pu I and Pu II making use of trends predicted by ab initio calculations. This same model has been used to describe the energy levels of Pu/sup 3 +/ in LaCl/sub 3/, and an extension has permitted preliminary calculations of the spectra of other valence states
Element identification in Przybylski's star
The method of Hartoog, Cowley, and Cowley (1973) is applied to the general question of element identification in HD 101065, which is often referred to as 'Przybylski's holmium star'. Three spectrograms are analyzed for wavelength coincidences, and a search is conducted for 187 atomic and ionic spectra of 92 elements. Most of the lanthanides, Ca II, and Y II are positively identified, but only weak evidence is found for the iron-peak elements. Some general remarks are made concerning the relative abundances (or absence) of Fe, Co, Y, Zr, Te, Tb, Lu, Yb, Nd, and U. No evidence is obtained for spectral variations or significant radial-velocity variations. It is concluded that iron-peak elements are present in this star, that their spectra are unusually weak with the possible exception of Co I, and that HD 101065 is apparently the only star of the magnetic chemically peculiar sequence with a lanthanide/iron-peak abundance ratio greater than unity.Peer reviewed: YesNRC publication: Ye
Recommended from our members
Fluorescence and excitation spectra of Bk/sup 3 +/, Cf/sup 3 +/, and Es/sup 3 +/ ions in single crystals of LaCl/sub 3/
Self-fluorescence measurements have two disadvantages: the excitation and relaxation mechanisms are not understood, therefore the fluorescing level is difficult to assign, and fluorescence from daughter ions is also present. To obtain the 5f/sup n/ ion energy level structure with the highest possible precision, ions dilutely substituted into single crystal host lattices are needed. Concentrated systems such as EsBr/sub 3/ will exhibit line broadening due to ion-ion interactions. This limits the usefulness of any pure system. The use of dye laser techniques to study the energy level structure of the heavier actinides in single crystals of LaCl/sub 3/ is discussed. (GHT