Rare Earth Spectra

SummaryA brief formulation and an overview of the magnetic diffusion mechanism is presented. The atomic physics of the rare earth spectra is considered. It is demonstrated that basic differences among these elements contribute to the observed abundance anomalies of rare earth elements. The ion fractions of the rare earth display very different behaviour with temperature and pressure. In the atmospheres of Ap stars, europium tends to have the greatest degree of ionization. While previous studies on the diffusion mechanism with model atmospheres have maintained chemical homogeneity, we argue that this is an unrealistic approach to the Ap stars and present the consequences in the light of the diffusion picture.

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Divalent Rare Earth Spectra Selection Rules and Spectroscopy of SrCl2:Sm2+

Physical Review ◽

10.1103/physrev.130.945 ◽

1963 ◽

Vol 130 (3) ◽

pp. 945-952 ◽

Cited By ~ 80

Author(s):

J. D. Axe ◽

P. P. Sorokin

Keyword(s):

Rare Earth ◽

Selection Rules ◽

Rare Earth Spectra

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Comparison of Sm II transition probabilities

Canadian Journal of Physics ◽

10.1139/p08-020 ◽

2008 ◽

Vol 86 (8) ◽

pp. 1033-1038 ◽

Cited By ~ 16

Author(s):

J E Lawler ◽

E A Hartog ◽

C Sneden ◽

J J Cowan

Keyword(s):

Rare Earth ◽

Ab Initio ◽

Transition Probabilities ◽

Chemical Elements ◽

Experimental Methods ◽

Research Note ◽

Atomic Transition ◽

Basic Data ◽

Theoretical Methods ◽

Rare Earth Spectra

This Research Note provides a comparison of experimental atomic transition probabilities in Sm~II from two recent publications. Basic data of this type for rare-earth spectra, including Sm~II, are very difficult to determine using ab-initio theoretical methods. Experimental programs are underway in several laboratories to determine these data for ongoing astrophysical studies of the origins of the chemical elements. The two recent and nearly simultaneous publications, which were based on very different experimental methods, provide transition probabilities in good, but not perfect, agreement.PACS Nos.: 32.70.Cs, 32.70.Fw, 32.30.Jc

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Modified ionic states in crystals

Mathematical Proceedings of the Cambridge Philosophical Society ◽

10.1017/s0305004100010768 ◽

1932 ◽

Vol 28 (4) ◽

pp. 522-530 ◽

Cited By ~ 3

Author(s):

C. P. Snow ◽

F. I. G. Rawlins

Keyword(s):

Rare Earth ◽

Theoretical Prediction ◽

Spectroscopic Properties ◽

Strong Absorption ◽

Perfect Agreement ◽

Rare Earth Spectra ◽

Molecular Origin ◽

Ionic States ◽

Theoretical Intensity ◽

The Rare Earth

After a review of the magnetic and spectroscopic properties of compounds of the rare earth and of transitional elements of the first group, the types of bands in spectra of the latter are considered in detail. Reasons are advanced for the view that these are of “molecular” origin in ferric salts, but that the spectra of some transitional compounds contain lines which cannot be regarded in this way. Such lines are shown to be ionic, or quasi-ionic, and accord well with the suggestion of inter-combination transitions such as 4F—2G.The theoretical intensity conditions, as a function of multiplet intervals, are in agreement with the observed appearance of intercombination transitions in Cr, and possibly also in Mn and Co. Similar considerations apply to the rare-earth spectra. As an example we have shown that the strong absorption in Pr and Nd compounds, and the much weaker lines found in Sa and Eu, are in perfect agreement with the theoretical prediction of intercombinations.

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