Uranium spectrum

Actinide spectra reflect the characteristic features of the 5/ orbitals which can be considered as both containing the optically active electrons and belonging to the core of filled shells. The electronic transition spectra of actinide ions in solution are dominated by the structure of the / levels and transitions within the / shell. Free-atom spectra provide more information about the interactions between the 5/ and the valence electrons. The emission spectra of the free actinide atoms have an enormous number of lines. In the uranium spectrum, about 100,000 lines have been measured, from which about 2500 lines have been assigned. 

Gr. helios, the sun). Janssen obtained the first evidence of helium during the solar eclipse of 1868 when he detected a new line in the solar spectrum. Lockyer and Frankland suggested the name helium for the new element. In 1895 Ramsay discovered helium in the uranium mineral clevite while it was independently discovered in cleveite by the Swedish chemists Cleve and Langlet at about the same time. Rutherford and Royds in 1907 demonstrated that alpha particles are helium nuclei. 

Gr. technetos, artificial) Element 43 was predicted on the basis of the periodic table, and was erroneously reported as having been discovered in 1925, at which time it was named masurium. The element was actually discovered by Perrier and Segre in Italy in 1937. It was found in a sample of molybdenum, which was bombarded by deuterons in the Berkeley cyclotron, and which E. Eawrence sent to these investigators. Technetium was the first element to be produced artificially. Since its discovery, searches for the element in terrestrial material have been made. Finally in 1962, technetium-99 was isolated and identified in African pitchblende (a uranium rich ore) in extremely minute quantities as a spontaneous fission product of uranium-238 by B.T. Kenna and P.K. Kuroda. If it does exist, the concentration must be very small. Technetium has been found in the spectrum of S-, M-, and N-type stars, and its presence in stellar matter is leading to new theories of the production of heavy elements in the stars. 

Gamma rays of various energy are emitted by potassium-40, thorium, uranium, and the daughter products of these two last elements contained in the earth formations surrounding the borehole. These elements occur primarily in shales. The gamma rays reaching the borehole form a spectrum typical of each formation extending from a few keV to several MeV. 

Spectral Gamma Ray Log. This log makes use of a very efficient tool that records the individual response to the different radioactive minerals. These minerals include potassium-40 and the elements in the uranium family as well as those in the thorium family. The GR spectrum emitted by each element is made up of easily identifiable lines. As the result of the Compton effect, the counter records a continuous spectrum. The presence of potassium, uranium and thorium can be quantitatively evaluated only with the help of a computer that calculates in real time the amounts present. The counter consists of a crystal optically coupled to a photomultiplier. The radiation level is measured in several energy windows. 

CsPuF6 was prepared and verified to be isostructural with corresponding compounds of uranium and neptunium. Its decomposition was studied in an inert gas atmosphere and in vacuum. Its spectrum has been measured in the region 400-2000 nm. The energy level structure of Pu5+ in the trigonally distorted octahedral CsPuF6 site was computed from a predictive model and compared with the observed spectrum. 

Si(Li) spectroscopy, with the capability of simultaneous quantitative analysis of 72 elements ranging from sodium through to uranium in solid, liquid, thin film and aerosol filter samples. The penetrating power of protons allows sampling of depths of several tens of microns, and the beam itself may be focussed, rastered or varied in energy. The use of a proton beam as an excitation source offers several advantages over other X-ray techniques, for example there is a higher rate of data accumulation across the entire spectrum which allows for faster analysis. 

The plutonium-uranium fuel cycle has particular advantages in fast spectrum... 

In the case of other elements, for instance Uranium, the emission spectrum normally displays thousands of narrowly spaced lines. However, the emission source possesses a fixed amount of energy which shall be spread up eventually amongst the thousands of lines thereby minimizing the sensitivity of each line. Hence, it is rather difficult to examine the less sensitive complex spectra of elements such as uranium. 

The spectrum of uranium vapor is complex with more than 3 x 10s lines in the visible region. Still, many of these are sharp and show sufficient isotope separation to permit selective excitation. The basic idea of AVLIS is to irradiate uranium vapor at a concentration around 1013 atoms cm-3 (higher concentrations are ineffective... 

Ives et al. (79) tended to reject our hypothesis that brown colours of mixed oxides (and in particular less pure NdaOs) are due to traces of praseodymium. However, these authors noted the interesting effect that such dark colours (also of Pro,oaTho.9802) bleach in the reflection spectrum at higher T. It was noted that mantles of NdaOa alone rapidly hydrate to a pinkish powder (carbonate ) in humid air. It is weU-known that -type sesquioxides are far more reactive, and for instance dissolve almost instantaneously in aqueous acid, than cubic C-type samples. Ives et al. 19) also studied the broad continuous spectrum of the orange light emitted from Thi- 11 0 2+2/ where the oxidation state of uranium is rather uncertain. 

This complex, unlike the simple homoalkyls of uranium 133), is stable at room temperature but decomposes without melting at 85 °C. The NMR spectrum of the diamagnetic complex confirms the presence of a Th—C a bond coordinated through the methylene carbon [t, 8.90 ppm singlet (2) t, 3.60 ppm doublet (2) t, 3.15— 2.60 ppm multiplet (3)]. Both the NMR and infrared spectra are in accordance with those of the presumably isostructural tetrabenzylzirconium and hafnium complexes. Also reported was the thorium(III) complex (C6H5CH2)3Th-THF. 

Tetraallyluranium [143, 144) and tetra(2-methylallyl)-uranium(IV) [145) are prepared by the reaction of the Grignard reagents with uranium tetrachloride in diethyl ether. The PMR spectra of these temperature-sensitive compounds are listed in Table 7. The AMgXa [146) pattern exhibited by tetraallyluranium is typical of the symmetrical jr-allyl structure in Fig. 14. The spectrum of tetra-... 

Line III has a great interest, because it takes into account in the case of U partial localization effects of 5f states. Such partial localization effects, if present in uranium metal, should be even more visible in the emission of plutonium metal. For this reason, line III will be discussed after the analysis of the valence band spectrum of plutonium metal. 

Fig. 12. UPS spectra of uranium metal (the surface of the metal is perfectly clean, as shown by the absence of an 02 p signal in the spectrum from Ref. 66)...

Fig. 15. Angle-integrated photoelectron energy distribution curves of uranium in the region of the giant 5 d -> 5 f resonance (90 eV < hv < 108 eV). The 5 f intensity at Ep is suppressed by more than a factor of 30 at the 5 ds/2 threshold (see the spectra for hv = 92 and 94 eV) and resonantly enhanced above threshold (see, e.g., the spectrum for hv = 99 e V). At an initial energy 2.3eV below Ep a new satellite structure is observed which is resonantly enhanced at the 5 d5/2 and 5 ds onsets. At threshold the satellite coincides with the Auger electron spectrum, which moves to apparently larger initial energies with increasing photon energy (from Ref. 67)...

Here, the main features of the valence band results for Th02 and UO2 will be illustrated. Since a large number of publications exists in this field (especially for uranium oxides), reference will be made only to a few selected investigations, chosen for the purpose of highlighting those aspects of the oxide bond discussed previously. A very comprehensive review of these results can be found (and references therein electronic and spectroscopic properties in Refs. 109-111). Figure 21 shows the photoemission spectrum of Th02 and UO2 up to Et = 45 eV The valence band region extends to about 10 eV. The marked difference is the appearance in UO2 of a sharp and intense peak at Et =... 

In the cellular multiple scattering model , finite clusters of atoms are subjected to condensed matter boundary conditions in such a manner that a continuous spectrum is allowed. They are therefore not molecular calculations. An X type of exchange was used to create a local potential and different potentials for up and down spin-states could be constructed. For uranium pnictides and chalcogenides compounds the clusters were of 8 atoms (4 metal, 4 non-metal). The local density of states was calculated directly from the imaginary part of the Green function. The major features of the results are ... 

The green crystals of bis(i78-cyclooctatetraene)uranium(IV) are air and water sensitive and only slightly soluble in aromatic and polar organic solvents. The visible spectrum is characteristic. 615 (1850) 641 (890) 660 (600) and 680 nm (350 L/mole-cm). The 1R spectrum shows only four strong bands at 3000,1430,900, and 741 cm 1.4... 

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