Density-functional calculations of alpha, beta, gamma, delta, delta', and epsilon plutonium

Total energies for the six known polymorphs of plutonium metal have been calculated within spin and orbital polarized density-functional theory as a function of lattice constant. Theoretical equilibrium volumes and bulk moduli correspond well with experimental data and the calculated total energies are consistent with the known phase diagram of Pu. It is shown that a preference for the formation of magnetic moments, increasing through the alpha-->beta-->gamma phases, explains their position in the ambient pressure phase diagram and their anomalous variation of atomic density. A simple model is presented that establishes a relationship between atomic density, crystal symmetry, and magnetic moments which is universally valid for all Pu phases.     

Carbon-13 and fluorine-19 NMR spectroscopy of the supramolecular solid p-tert-butylcalix(4)arene.alpha,alpha,alpha-trifluorotoluene

The supramolecular 1:1 host-guest inclusion compound, p-tert-butylcalix[4]arene x alpha,alpha,alpha-trifluorotoluene, 1, is characterized by 19F and 13C solid-state NMR spectroscopy. Whereas the 13C NMR spectra are easily interpreted in the context of earlier work on similar host-guest compounds, the 15F NMR spectra of solid 1 are, initially, more difficult to understand. The 19F[1H] NMR spectrum obtained under cross-polarization and magic-angle spinning conditions shows a single isotropic resonance with a significant spinning sideband manifold. The static 19F[1H] CP NMR spectrum consists of a powder pattern dominated by the contributions of the anisotropic chemical shift and the homonuclear dipolar interactions. The 19F MREV-8 experiment, which minimizes the 19F-19F dipolar contribution, helps to identify the chemical shift contribution as an axial lineshape. The full static 19F[1H] CP NMR spectrum is analysed using subspectral analysis and subsequently simulated as a function of the 19F-19F internuclear distance (D(FF) = 2.25 +/- 0.01 A) of the rapidly rotating CF3 group without including contributions from additional libration motions and the anisotropy in the scalar tensor. The shielding span is found to be 56 ppm. The width of the centerband in the 19F[1H] sample-spinning CP NMR spectrum is very sensitive to the angle between the rotor and the magnetic field. Compound 1 is thus an attractive standard for setting the magic angle for NMR probes containing a fluorine channel with a proton-decoupling facility.     

Gd, U, Pu and Cm alpha particle energy analysis using tracks in solids

This paper presents advances in a procedure for alpha particle analysis using the nuclear tracks formed in solid-state materials. This method is based on the relationship between the energy deposited in the material by ionizing particles and the track developed after a well-established chemical process. The experimental study included alpha particles in the energy range from 3.2 to 5.8 MeV emitted by ¹⁴⁸Gd, ²³⁸U, ²³⁹Pu and ²⁴⁴Cm. The quantitative results provide a clear signature to identify each one of the radioisotopes based on the formed track parameters. The track analysis is performed with a digital image analysis system associated with a PC mathematical processor. The wide range energy response makes this method a promising analysis system.     

Intensity ratios of mesonic x-ray linesK_{\alpha _1 } , K_{\alpha _2 } andL_{\alpha _1 } , L_{\beta _2 }

Intensity ratios ofμ-mesonic x-rays in some heavy elements are discussed. Intensity ratios of the \(K_{\alpha _1 } /K_{\alpha _2 } \) and \(L_{\alpha _1 } /L_{\beta _2 } \) lines have been calculated for²⁰⁶Pb,²⁰⁹Bi and²³⁸U with relativistic wavefunctions and retardation effect. Though for a refined calculation, it is necessary to take into consideration several features that are peculiar to mesonic atoms, the present calculations have shown that the observed intensity ratios of mesonic x-rays are not anomalous.     

Luminescent response from BeO exposed to alpha,beta and X radiations

This work presents the TL and OSL response of beryllium oxide detectors exposed to alpha, beta and X radiation beams. The samples were characterized, and they presented good reproducibility, good linearity interval, low energy dependence, and an acceptable fading. The luminescent response was better for the OSL technique.     

α，α′-二氧代烯酮环二硫代缩酮类化合物的谱学研究

研究了5种含有苯环取代基的α，α′—二氧代烯酮环二硫代缩酮类化合物的红外光谱的特征吸收规律，指出了这类化合物分子结构对红外吸收谱带的影响；对^1H NMR，^13C NMR共振谱带做了全面的归属。并且讨论了分子结构对^1H NMR，^13C NMR共振谱带化学位移的影响，其变化规律与红外光谱一致，为这类化合物的结构及谱学研究提供了启发性的模式。     

Time-varying alpha and particle physics

We argue that models in which an observable variation of the fine structure constant is explained by motion of a cosmic scalar field are not stable under renormalization and require massive fine-tuning that cannot be explained by any known mechanism.     

Calculation of hydrogen generation from plutonium-induced alpha radiolysis of nitric,sulfuric, and perchloric acids

Abstract

Uranylion was reduced to U⁴⁺ by ionizing radiation in deoxygenated solutions containing organic solutes. This reduction is effected by free radical species formed from the organics and perhaps in part by H atoms from H₂O decomposition. A detailed study of uranyl oxalate solutions showed that the role of H₂O₂ in this system is complex and that chain-type reactions involving this species can occur.     

Synthesis,characterization, and electrochemical performances of alpha nickel hydroxide by coprecipitating Sn2+

Ionics - Sn-substituted α-Ni(OH)2 for Ni-MH battery is prepared by supersonic coprecipitating method, using NiSO4 as nickel ion source and SnSO4 as doping material. The crystal structure and...     

104 MeV alpha particle scattering from90, 92Zr

Differential cross sections have been measured for the elastic and inelastic scattering of 104 MeV alpha-particles from^{90, 92}Zr. The experimental data are analyzed in terms of coupled channels on the basis of a flexible anharmonic vibrator model and using different parametrizations of the radial shape of the extended optical potential. The results favour the squared Saxon-Woods type for the real part. Additionally to a radial momentum analysis of the real potentials a semimicroscopic folding model has been applied for extracting isoscalar quadrupole and hexadecapole transition rates.     

α，α′—二氧代烯酮环二硫代缩酮类化合物的紫外光谱研究

在两种不同溶剂条件下，研究了5种α，α′－二氧代烯酮环二硫代缩酮类化合物的紫光光谱特性。在同一种溶剂条件下，比较含氮化合物与含硫化合物的紫外光谱特性，指出了它们随化学结构不同而变化的规律。     

α,α‘—二氧代烯酮环二氮代缩酮的特征红外光谱

本文研究了α，α＇－二氧代烯酮环二氮代缩酮的特征红外光谱，指出了它们随化学结构而变化的规律。     

Proton and alpha radioactivity of very neutron deficient Te,I, Xe and Cs isotopes,studied after electrostatic separation

In fusion reactions of⁵⁸Ni beams with⁵⁴Pe and⁵⁸Ni target nuclei neutron deficient evaporation residues have been produced and separated from the beam in an electrostatic deflector with large acceptance. The recoil nuclei were implanted and detected in an array of 100 PIN photodiodes, where also their particle decays were recorded. The assignment of the 0.81 MeV proton line to the decay of¹⁰⁹I could be experimentally proven by the observation, that it is followed by the 3.31 MeV alpha emission from¹⁰⁸Te. A proton decay from¹¹²Cs was not observed. The decay energies of a number of known emitters have been measured with better precision.Dedicated to Prof. Dr. P. Kienle on the occasion of his 60th birthday