Energy trivalent actinide

In what follows we briefly review some of the previous attempts to analyze the available spectra of plutonium (6). In addition, we estimate energy level parameters that identify at least the gross features characteristic of the spectra of plutonium in various valence states in the lower energy range where in most cases, several isolated absorption bands can be discerned. The method used was based on our interpretation of trivalent actinide and lanthanide spectra, and the generalized model referred to earlier in the discussion of free-ion spectra. 

Electronic Energy Level and Intensity Correlations in the Spectra of the Trivalent Actinide Aquo Ions. I. Es3+, W.T. Camall, D. Cohen, P.R. Fields, R.K. Sjoblom, and R.F. Bames, J. Chem. Phys. 59, 1785-1789 (1973). 

We have calculated sets of theoretical energy levels for the trivalent actinides and lanthanides and correlated these levels with transitions observed in the solution absorption spectra of these elements. Using the eigenvectors resulting from this energy level calculation, we have computed the theoretical matrix elements required to account for the observed band intensities in the two series of elements. The extent to which the theoretical calculations can be correlated with experimental results has been discussed, and some applications for the intensity relationships are pointed out. 

The same type of approach in terms of fitting energy levels to the absorption bands observed in the trivalent actinide elements has already been reported (4). Here the problems were somewhat more formidable because of the paucity of crystal data and the much greater density of levels observed in the spectral region over which solution absorption spectra could be obtained. Experimental data and calculated energy... 

Table I. Parameters Used to Calculate Energy Levels Observed in the Solution Absorption Spectra of the Trivalent Actinides and Lanthanides...

The ionization of Lr would be expected to stop with the f- core intact because of the enhanced binding energy of possible valence electrons in the filled f shell. The stable valence state of Lr would then be the (III) state. Experiments to confirm this oxidation state of Lr were undertaken by Silva and coworkers (1). They compared the extraction behavior of Lr with several tri- and tetravalent actinides and with Ba +, Ra +, and No +. A chelating extractant, thenoyltrifluoroacetone dissolved in methyl isobutyl ketone, was employed to extract the tracer ions from aqueous solutions that had been buffered with acetate anions. Their results, shown in Figure 8, very clearly demonstrate that Lr is extracted within the same pH range as the trivalent actinides, and therefore, proves that Lr is trivalent. 

Figure 7. Energy levels of trivalent actinide ions (----------predicted levels ...

An examination of the trivalent actinide energy level schemes reveals several possibilities for laser action. These are discussed in light of the general properties cited above. Only conventional broadband optical pump sources are considered. Obviously with selective laser excitation and cascade lasing schemes, stimulated emission from many more states should be possible, but these special situations are too numerous to be considered in detail here. 

Mochizuki and Okamoto applied the Dirac program for the estimation of stabilities of trivalent actinide elements and water or ammine complexes (Mochizuki and Okamoto 2002). Mochizuki and Tatewaki (2002) also carried out the electronic structure calculation on the hexa-hydrated ions of curium and gadolinium. They used the Dirac program and also predicted the fluorescence transition energy using the Complete Open-Shell Configuration Interaction (COSCI) method. Even the hexa-hydrate curium ion needs 2,108 basis functions for the fully relativistic four-component calculation. 

Fig. 24. (a) The calculated s, p and d occupation numbers across the actinide series when the 5f states are part of the core. The full line is for trivalent actinides and the dashed line is for divalent actinides, (b) The calculated s, p, d and f occupation numbers across the actinide series when the 5f states are in the energy bands. 

Knauer, J. B. and Weaver, B. (1968) Separation of Berkelium from Trivalent Actinides by Chromate Oxidation and HDEHP Extraction, US Atomic Energy Commission Document ORNL-TM-2428, Oak Ridge National Laboratory. 

For the trivalent actinides, as for the trivalent lanthanides, ligand field effects are relatively small. In a number of instances, isolated bands in Fig. 16.2 can be interpreted as envelopes which constitute a sum over transitions to all the crystal field components of discrete SU states within the 5f configuration. The effect of the environment is to remove the degeneracy of the free-ion state, but the resulting crystal field components exhibit an energy spread of only about 200-300 cm . The center of gravity of such absorption bands is often referred to... 

The intensity analysis of trivalent actinide ions in an aqueous solution of HCIO4 (or DCIO4) has been reviewed by Carnall and coworkers (Carnall et al. 1983, Carnall and Crosswhite 1985, 1986). Since the f states of the actinides occur in a smaller energy range than the f states of the lanthanides, the density of states in the optical region of interest is high for the actinides. It is difficult to assign a free-ion label to... 

A. Moritz, X. Cao, and M. Dolg, Quasirelativistic energy-consistent 5f-in-core pseudopotentials for trivalent actinide elements, Theor Chem. Acc., 117, 473-481 (2007). 

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