Uranyl spectrum

The triacetate uranyl complex (24) is structurally similar to the trinitrate uranyl complex (6) (three bidentate ligands arranged equa-torially around the uranyl O—U—O axis). It was expected that the visible, near ultraviolet spectrum of the triacetate uranyl complex would be similar to the spectrum of U02(N03)3 as are the spectra of 1102(804)3, 1102(003)3 , and other uranyl complexes which apparently have the same structure (17). The absorption spectrum of uranyl acetate extracted into tri-n-octylamine in xylene from dilute acetic acid is different from the trinitrato uranyl spectrum. This indicates that the triacetate uranyl complex is probably not the species involved. By analogy to the uranyl nitrate system 14), formation of a tetraacetate uranyl complex might be expected. The purpose of this work is to determine the nature of the anionic hexavalent actinide acetate complexes and to identify the species involved in the amine extraction and anion exchange of the hexavalent actinides from acetate systems. 

A special case in the uranyl spectroscopy is formed by Denning s extensive work on the UO + group in Cs2U02Cl4C ([65], and papers cited therein). Later this work was extended to two-photon spectroscopy, a powerful method for a complex with inversion symmetry [66]. Excited state spectroscopy followed soon after [67], The latter experiments show a progression in the excited-state absorption spectrum of the UO + complex in a frequency of 585 cm-1. This is the U-O stretching frequency in the second excited state. In the first excited state it is at 715 cm-1. In this way it is possible to determine that the U-O distance expands from 1.77 A in the ground state to 1.84 A in the first and 1.95 A in the second excited state. This work has been reviewed recently [68]. 

Figure 5.7 Raman spectrum of uranyl />/ v-(2-hydroxynaphthaldchydc) (cm ). (From Ref. 340, with permission.)...

Figure 5. Triboluminescence Spectrum of Uranyl Nitrate Hexa-hydrate. The photoluminescence excitation spectrum is shown for comparison the photoluminescence emission has been...

Absorption Spectrum and Other Properties of the Excited Uranyl Ion. 145... 

One of the most successful techniques of detecting small amounts (say 10-9 to 10 6g) of uranium is the fluorescence after incorporation in molten sodium fluoride22,181). Since the light emitted is green, and since the emission spectrum shows some vibrational structure, it was the general opinion before 1956 that some kind of imbedded uranyl... 

We would like to mention the fascinating triboluminescence239 of uranyl nitrate, where the emitted spectrum looks like photoluminescence, whereas several other triboluminescent materials crushed in nitrogen or neon give the characteristic spectra of electric discharges in the surrounding gas. 

The Raman spectrum of uranyl nitrate hexahydrate was followed from 15 to 290 K (49). The changes taking place as a function of temperature were obtained by following the Raman spectra in the OH stretching region. 

Emission Spectra. The emission spectra of the uranyl acetate dihydrate in solution and in the solid state are shown in Figure 1. The fine structure in the solid state spectrum is not observed in solution. The corresponding emission spectra of uranyl-exchanged zeolites. A, Y, mordenite and ZSM-5 are shown in Figures 2-4. Excitation is carried out at 366 nm. The emission spectra have been scanned in all cases between 450 nm and at least 630 nm. 

The emission spectra for uranyl-exchanged zeolites Y, mordenite and X all have differences but do show some fine structure and therefore resemble the solid state spectrum of uranyl acetate dihydrate. In fact, the spectrum of uranyl ions exchanged into sodium mordenite is very similar to that of the uranyl acetate dihydrate solid spectrum shown in Figure 1. Further support for our belief that some zeolites have a solution like environment and others have a solid like environment comes from the correlation between the crystallinity of these uranyl-exchanged zeolites and the appearance of some fine structure in the emission spectrum. We find no apparent correlation between this fine structure and the concentration of the uranyl ion in the zeolites even with a ten-fold change in the concentration of the uranyl ion. 

In terms of spectroscopic properties, the uranyl superphthalocyanine complexes 160-162 display features which, although reminescent of, differ substantially from those of the phthalocyanine. The IR spectrum exhibits a strong v(OUO) stretching transition at 925 cm (KBr pellet) [112,118,119] or 933 cm" (evaporated film)... 

In addition, the electronic spectrum of uranyl superphthalocyanine 160 is significantly different from those of known metal phthalocyanine complexes... 

Solvent-solvent and solvent-solute interactions were examined by measuring the Raman spectrum of CO2 in neat "C02 and in solutions of -diketones (acacH, tfacH and hfacH) or the complex [U02(hfac)2DMS0]". It was found that the Raman bands of "C02 containing -diketones are shifted to lower wave numbers compared to neat CO2 and no shift to lower wave numbers was observed for the uranyl complex solution. Acid-base interactions between the carbonyl oxygen atoms of diketonato ligand and... 

An infrared spectrum of the product provides a quick check on the presence of U(VI). The uranyl ion in incompletely reduced samples exhibits a strong peak at 930 cm. , while the nearest acetate band is at 965 cm. ... 

Chlorotris(//-cyclopentadienyl)uranium(IV) is an oxygen-sensitive brown solid. It can be handled in air for brief periods of time with minimal oxidation, which is evidenced by darkening of the color. The compound is soluble in ethereal and aromatic solvents but only sparingly soluble in aliphatic hydrocarbons. Solutions are exceedingly air-sensitive. The nmr spectrum in benzene exhibits a sharp singlet 9.6 ppm to high field of the solvent (r 12.4). The infrared spectrum (Nujol mull) exhibits typical 7t-cyclopentadienyl bands at 1013 (m) and 784 (s) cm i. Oxidation is evidenced by the appearance of the antisymmetric v(OUO) stretch of the uranyl group at 930 cm-i. 

A characteristic example of case (b) is the uranyl ion (UO ). The Tie = 0— rig = 2 line dominates in the spectrum (Fig. 4b). The tungstate ion (WC)4 ) is a good example of case (c). The very broad emission spectrum (see Fig. 4c) does not show any vibrational structure at all, the Stokes shift is very large (—16,000 cm" ) and the zero-vibrational transition is not observable, not even at the lowest possible temperatures nor for the highest possible resolving powers. 

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