Optical Spectra and Electronic Structure of Actinide Ions in Compounds and in Solution

Abstract

DISCLAIMER (1959)......t................................ Free-ion Energy Levels and Parameters for Pr AbstractThis report provides a summary of theoretical and experimental studies of actinide spectra in condensed phases. Much of the work was accomplished at Argonne National Laboratory, but references to related investigations by others are included.Spectroscopic studies of the trivlent actinides are emphasized, as is the use of energy level parameters, evaluated from experimental data, to investigate systematic trends in electronic structure and other properties.Some reference is made to correlations with atomic spectra, as well as with spectra of the (II), (IV), and higher valence states.

Incorporation of trivalent actinides into calcite: A time resolved laser fluorescence spectroscopy (TRLFS) study

“…The Cm 3+ fluorescence emission spectra of the 6 D 7/ 2 fi 8 S 7/2 transition were obtained when exciting the most intense absorption maxima (396.6 nm) of Cm 3+ (Carnall and Crosswhite, 1985). The fluorescence emission of the Cm 3+ aquo ion shows a peak maximum at 593.8 nm (Fig.…”

“…Without an OH-quencher in the first coordination sphere of Cm(III), the calculated decay rate is 770 s À1 (Carnall and Crosswhite, 1985), this corresponds to a radiative lifetime (reciprocal decay rate) of 1.3 ms. This value is verified for the Cm 3+ lifetime measurements in D 2 O.…”

Diffuse reflectance spectroscopy of neptunium ions in polycrystalline ceramics designed for immobilization of HLW

“…In the present work, DR spectra of perovskite, zirconolite and thorutite samples containing various amounts of Np were collected over the near-infrared (NIR) and visible range (4000-25000 cm −1 ) to assist the definition of Np valences in these polycrystalline materials. Electronic absorption is expected in this spectral region for Np 3+ (f 4 ), Np 4+ (f 3 ) and Np 5+ (f 2 ) ions, arising from intraconfigurational f-f transitions [15][16][17][18]. Bandshifts and possible band splittings are also expected on doping of Np ions into crystalline oxide lattices and the actual absorption band intensities will largely depend on the Np local symmetry.…”

“…In the literature, little theoretical modelling of Np 3+ and Np 4+ spectra in the condensed phase with well-defined symmetry character has been attempted [15][16][17][18]. The complexity of Np 3+ and Np 4+ spectra arising from transitions within partly filled 5f shell is mainly due to the fact that there is a large number of free-ion states which lie close to one another and which are further split by crystal fields being of the same order of magnitude as the interelectronic repulsion and the spin-orbit coupling [18].…”

Diffuse reflectance spectroscopy of tetravalent neptunium and plutonium ions in ThO2

“…In addition, Th 4+ has a similar ionic radius as other actinide ions so it can be substituted by other actinide ions without much site distortion [11], especially if the substituted actinide ion is tetravalent. In the literature, little theoretical modelling of Np 4+ and Pu 4+ spectra in the condensed phase with well-defined symmetry character has been attempted [12]. The complexity of Np 4+ and Pu 4+ spectra arising from transitions within partly filled 5f shells is mainly due to the fact that there is a large number of free-ion states which lie close to one another and which are further split by crystal fields which have the same order of magnitude as the inter-electronic repulsion and the spin-orbit coupling [13].…”