Fe and N diffusion in nitrogen-rich FeN measured using neutron reflectometry

Grazing incidence neutron reflectometry provides an opportunity to measure the depth profile of a thin film sample with a resolution <1 nm, in a non-destructive way. In this way the diffusion across the interfaces can also be measured. In addition, neutrons have contrast among the isotopes, making it feasible to measure the self-diffusion. In the present work, the isotope multilayers of [FeN/⁵⁷FeN]₁₀ and [FeN/Fe¹⁵N]₁₀ were prepared using magnetron sputtering and self-diffusion of Fe and N was investigated. It was found that N diffusion is slower compared to Fe and does not follow the atomic size dependence.      

Inelastic neutron scattering from isotactic polypropylene

We used inelastic neutron scattering to probe the low‐energy excitations in semicrystalline isotactic polypropylenes with different degrees of crystallinity. The contributions from the amorphous and crystalline regions to the total scattering intensity were extracted under the assumption of a weighted linear contribution of the two regions in a simplified two‐phase system. The resulting intensity from the amorphous region showed a peak at 1.2 meV that was in good agreement with the previously determined boson peak characteristic of atactic polypropylene. The possibility of a contribution to the boson peak region by longitudinal acoustic mode modes that are characteristic of semicrystalline polymers and appear in the same low‐frequency region is discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2852–2859, 2001     

Eine einfache Mehrprobenrotationsanordnung zur Aktivierungsanalyse am Neutronengenerator

Es wird eine Anordnung beschrieben, die es gestattet, bis zu 7 Proben unter identischen Bedingungen rotationssymmetrisch zu aktivieren. Die Proben rotieren um zwei parallele Achsen. Es wird über Erprobungsmessungen durch Aktivierung von Cu-und N-haltigen Proben berichtet.     

On the moment of inertia of a proto neutron star

The influences of σ* and Φ mesons,temperature and coupling constants of nucleons on the moment of inertia of the proto neutron star(PNS) are examined in the framework of relativistic mean field theory for the baryon octet {n,p,Λ,Σ+,Σ0,Σ+,Ξ-,Ξ0} system.It is found that,compared with that without considering σ* and Φ mesons,the moment of inertia decreases.It is also found that the higher the temperature,the larger the incompressibility and symmetry energy coeficient,and the larger the moment of inertia of a PNS.The influence of temperature and coupling constants of the nucleons on the moment of inertia of a PNS is larger than that of the σ* and Φ mesons.     

Improving the specularity of magnetic mirrors for atoms

An array of anti-parallel current-carrying wires creates an inhomogeneous magnetic field capable of reflecting neutral atoms. We present analytical and numerical analyses of the magnetic field produced by such an array, and describe methods for reducing the resulting rms angular deviation from specular reflection to less than 0.1 mrad. Careful choice of cross-sectional wire profiles is shown to dramatically improve specularity of reflection close to the surface. Additionally, we find that the specularity depends on whether the number of wires in the mirror is even or odd, and that there exists an optimal turning height above the surface that maximizes the specularity of reflection from the mirror. Received 16 November 1998     

Phase transitions in the H+-conducting perovskite ceramics by the quasi-elastic neutron and high-pressure Raman scattering

H⁺-containing lanthanide-doped perovskites A(Ba, Sr etc.)B(Zr, Ce, Ti etc.)O₃ are potential ceramic membranes for fuel cell and medium temperature water electrolysis (300–800 °C). The comparison studies of the hydrated and non-hydrated Yb-doped BaZrO₃ and SrZrO₃ were performed by thermal expansion, medium–high temperature neutron and room-temperature high-pressure Raman scattering. Neutron diffraction and elastic/quasi-elastic studies carried out for BaZrO₃ ceramic show the presence of the protons, their successive diffusion above ∼600 °C, and then their departure above 750 °C (under vacuum). Phase transitions and their modification by proton insertion are discussed. A high-pressure Raman study of SrZrO₃ performed at room temperature in the diamond anvil cell reveals the presence of two pressure-induced phase transitions at about 5 and 22 GPa and confirms that proton insertion modifies the phase transition sequences. Paper presented at the 11th EuroConference on the Science and Technology of Ionics, Batz-sur-Mer, Sept. 9–15, 2007.     

Analysis of inelastic neutron scattering results on model compounds of the nitrogenous bases of the nucleotides

The role that model compounds can play in understanding the vibrational eigenvectors of molecules is discussed. Assigning the spectra of model compounds is of particular importance and the individual-scaling approach, that has been used with isolated molecule ab-initio calculations, is outlined. Special emphasis is given to recent work on assigning the spectra of three 5–6 heterobicyclic systems; indole, benzimidazole and isatin.      

多维非定常中子迁移方程Galerkin有限元法近似解的收敛性和广义解的存在性

使用Galerkin有限元法研究了多维非定常中子迁移方程，证明了Galerkin有限元法近似解的收敛性和广义解的存在性．