Magnetic interface polarization of the La-5d states in Fe/LaHx multilayers

For rare-earth (RE)-hydrides (REHx), a metal-to-insulator transition is observed if the hydrogen concentration is increased from the dihydride (x=2) towards the trihydride (x=3). This transition provides an object for studies of the magnetic interface polarization in layered ferromagnet/insulator structures. For different samples with a fixed Fe and varied LaH_x sublayer thickness t_LaHx ([15 ? Fe/t? LaH_x]xn), the H concentration x in the LaH_x sublayer is gradually increased in the experiment. Starting from the as prepared dihydride REH_2-δ, the modification of the magnetic polarization of the La-5d states at the Fe/La_x interface is studied across the transition by magnetic circular dichroism measurements at the La-L₂ and L₃ edges. The experiments reveal an induced magnetic polarization of the La-5d hole states on a length scale of 9 ? that is independent of the altered electronic structure of the La-5d states. Received: 23 May 2001 / Accepted: 4 July 2001 / Published online: 5 October 2001     

Pressure dependence of the morphology and size of cobalt (II,III) oxide nanoparticles prepared by pulsed-laser ablation

Received: 18 September 1998/Accepted: 22 September 1998     

Phase-retrieval in hard x-ray diffraction imaging: Can we quantitatively reconstruct a “real” transmission function?

X-ray phase-retrieval algorithms are widely exploited in contemporary hard x-ray diffraction techniques to image at the nanoscale, less than 10-20 nm. Often reconstruction of the sample shape (image) suffices for the purpose of experiment. Identification of specimen composition requires a quantitative profiling of the complex refractive index. This Letter shows that, although such quantitative analysis is possible in many cases, there is a lower limit to variations in optical density, which can be quantitatively reconstructed using the common phase-retrieval methods.     

Optimality for (<Emphasis Type="Italic">h,φ</Emphasis>)-multiobjective programming involving generalized type-I functions

Based upon Ben-Tal’s generalized algebraic operations, new classes of functions, namely (h,φ)-type-I, quasi (h,φ)-type-I, and pseudo (h,φ)-type-I, are defined for a multi-objective programming problem. Sufficient optimality conditions are obtained for a feasible solution to be a Pareto efficient solution for this problem. Some duality results are established by utilizing the above defined classes of functions, considering the concept of a Pareto efficient solution. This research is supported by National Science Foundation of China under Grant No. 69972036.     

Correction to the Paper - Determination of a Domain in Complex Space by its Automorphism Group

The author offers some corrections to his article which appeared in Vol. 47, No. 3 of this journal.     

Calculation of the Slip Velocity of a Rarefied Gas on a Solid Spherical Surface with Allowance for Accommodation Coefficients

The slip velocity of a rarefied gas with inhomogeneous temperature and mass velocity on a solid spherical surface is calculated with the use of a twomoment boundary condition in the linear approximation in terms of the Knudsen number. The dependence of the slip velocity on accommodation coefficients of the two first moments of the distribution function is studied.     

Controlling the orientation and coverage of silica-MFI zeolite films by surface modification

The silica-MFI (Si-MFI) zeolite films are fabricated on α-Al₂O₃ supported silica-zirconia layers. The roughness and chemistry of the substrate surface are changed by surface modification with hydrogen peroxide and carboxymethyl chitosan (CMCS) solution to investigate their effects on the formation and orientation control of Si-MFI zeolite films. The AFM images reveal that the roughness of the silica-zirconia surface can be increased under the treatment of hydrogen peroxide. The Si-MFI zeolite films grown on the rough substrate surface are also b-oriented. Diffuse-reflectance FT-IR studies demonstrate that the abundance of functional groups such as -OH and -COOH can be successfully seeded onto the α-Al₂O₃ supported silica-zirconia layer through modification with CMCS solution. Continuous b-oriented Si-MFI zeolite films can be fabricated on the CMCS-modified α-Al₂O₃ supported silica-zirconia layer. It is evident that the orientation and microstructure of Si-MFI zeolite films on α-Al₂O₃ supported silica-zirconia layers are dominantly controlled by the chemical nature of the substrate surface, where the functional groups serve as the structure-directing matrix to induce the orientation and growth of the zeolite crystals with their b-axes perpendicular to the substrate surface.     

What is the fate of a black hole embedded in an expanding universe?

Within a large class of exact solutions of the Einstein equations describing a black hole embedded in a Friedmann universe it is shown that, under certain assumptions, only those with comoving Hawking–Hayward quasi-local mass are generic, in the sense that they are late-time attractors.     

Invalidating mechanism of bis (3-sulfopropyl) disulfide (SPS) during copper via-filling process

The invalidating process and related mechanism of bis (3-sulfopropyl) disulfide (SPS) during copper via-filling process were investigated by means of electrochemical polarization measurement, and the mass spectrometry (MS) testing was employed to confirm the molecular weight (MW) and the structure of SPS invalidating products. Meanwhile, quantum chemistry calculation was used to verify the rationality of the proposed invalidating course. These results suggest that the solution containing SPS has invalidated after the passed charges (PC) reached 15 Ah L⁻¹ under electrifying condition. The adsorption ability of SPS decrease gradually with the increase of PC during the invalidating process. The invalidation of SPS is an oxidation process related to the dissolved oxygen in the solution, during which the active functional group -S-S- is oxidized to -SO_x-SO_y-. As a result, the accelerating effect of SPS on copper reduction will gradually diminish.     

Localized exciton dynamics in AlInGaN alloy

Carrier recombination dynamics in AlInGaN alloy has been studied by photoluminescence (PL) and time-resolved PL (TRPL) at various temperatures. The fast red-shift of PL peak energy is observed and well fitted by a physical model considering the thermal activation and transfer processes. This result provides evidence for the exciton localization in the quantum dot (QD)-like potentials in our AlInGaN alloy. The TRPL signals are found to be described by a stretched exponential function of exp[(−t/τ)^β], indicating the presence of a significant disorder in the material. The disorder is attributed to a randomly distributed QDs or clusters caused by indium fluctuations. By studying the dependence of the dispersive exponent β on temperature and emission energy, we suggest that the exciton hopping dominate the diffusion of carriers localized in the disordered QDs. Furthermore, the localized states are found to have 0D density of states up to 250 K, since the radiative lifetime remains almost unchanged with increasing temperature.