Modulation of the internal structure and surface properties of natural and synthetic polymer matrices by graphene oxide doping

Controlling the surface properties and structure of thin nanosized coatings is of primary importance in diverse engineering and medical applications. Here we report on how the nanostructure, growth mechanism, thickness, roughness, and hydrophilicity of nanocomposites composed of weak natural or strong synthetic polyelectrolytes (PE) can be tailored by graphene oxide (GO) doping. GO reverses the build‐up mechanism affecting the internal structure and the hydrophilicity in a way depending on the type of the PE‐matrix. The extent of GO‐adsorption and its impact on the surface morphology was found to be independent on the type of the underlying PE‐matrix. The nanostructure of the hybrid films is not significantly altered when a single surface‐exposed GO‐layer is deposited, while increasing the number of embedded GO‐layers leads to pronounced surface heterogeneity. These results are expected to have valuable impact on the construction strategies of coatings with tunable surface properties.     

Time domain bidirectional beam propagation method for second harmonic generation in multilayers

We propose a time domain bidirectional beam propagation method based on scattering operators for wide band pulse propagation in nonlinear multilayers. The reported numerical examples demonstrate the applicability of the algorithm for the analysis of temporal effects related to the process of second harmonic generation.     

多层膜软X光反射镜的研制

本文介绍了镍-碳多层膜软X光反射镜的设计与制造方法,特别是膜厚监控法.用俄歇谱仪分析了一个样品的剖面情况;对一些样品在1.54(?)的衍射特性和在软X光区的反射率进行了测量并与理论计算结果作了比较.     

Ordinary and extraordinary cyclotron waves in metals

Dispersion equations for the ordinary and extraordinary cyclotron waves propagating perpendicular to the magnetic field in metals in the critical region where the wavelength is comparable to the electron Larmor radius are derived as an infinite but rapidly converging power series expansion in δ( = Ω/Ω-M). Numerical studies for the cyclotron wave propagation near the first seven resonances are carried out. The non-local behaviour of those waves in the critical region 01 ⩽ kR ⩽ 3-0 is studied. For the ordinary waves the first few resonances show significant dispersion than those near higher resonances which are dispersion-free. Only one extraordinary wave propagates near the fundamental cyclotron frequency. For the higher resonances, two modes propagate near each of the resonant frequencies, of which one mode remains constant for all values ofkR whereas the second mode shows significant dispersion. But beyond the fifth resonance both the modes are dispersion free.     

Ag/Si multilayers with nanometer sized particles of silver during annealing process

Thein situ low angle X-ray diffraction and transmission electron microscopy were used to monitor the interdiffusion characteristics as well as the microstructure in Ag/Si multilayers with modulated wavelength 7. 64 nm when annealing from 323 to 573 K. The interdiffusion mechanism of Ag/Si multilayers with immiscibility is different from that of other metal/Si multilayers which are miscible. Phase separation takes place at 323 K, then silicon atoms diffuse into silver sublayers through silver grain boundaries and separate silver sublayers into nanometer sized silver particles gradually at higher temperature. The mean size of silver particles is about 5 nm. The activation energy and frequency factor are determined to be 0.24 eV and 2.02 x⁻²⁰m²/s, respectively. An erratum to this article is available at .     

Synchrotron Mössbauer reflectometry using stroboscopic detection

The concept of the heterodyne/stroboscopic detection of nuclear resonance scattering of synchrotron radiation is extended to the grazing incidence geometry. Model calculations for an antiferromagnetic [⁵⁷Fe/Cr]₂₀ multilayer are shown and discussed. Principles and methodological aspects of stroboscopic synchrotron Mössbauer reflectometry are briefly reviewed.     

Structural evolution of a-Si:H/SiO2 multilayers upon step by step thermal annealing

a-Si:H/SiO_2 multilayers were prepared by alternatively changing plasma enhanced chemical vapour deposition of a-Si:H layers and in situ plasma oxidation process. Subsequently, as-grown samples were annealed at temperatures from 350℃ to 1100℃ in N_2 ambient with an increment of 100℃. The evolution of bonding configurations and structures with annealing treatments was systematically investigated by Fourier-transform infrared spectroscopy. The peak position of Si－O stretching vibration of SiO_2 layers shift to 1087cm^{-1} after annealing at 1100℃, which demonstrates that the SiO_2 films fabricated by plasma oxidation after high temperature annealing can have similar properties to the thermal grown ones. A Si－O vibration from interfacial SiO_x was identified: the value x was found to increase as increasing the annealing temperature, which is ascribed to the cooperation of hydrogen effusion and reordering of the oxygen bond in SiO_x networks. The H-related bonds were observed in the form of H－Si－O_3 and H－Si－Si_{3-n}O_n (n=1－2) configurations, which are supposed to be present in SiO_2 and interfacial SiO_x layers, respectively. The H atoms bonded in different bonding configurations effuse at different temperatures due to their different desorption energies.     

不连续Co/SiO2多层膜的结构及其输运性质的研究

用射频磁控溅射方法制备了系列Co/SiO2不连续磁性金属绝缘体多层膜（DMIM） .经研究发现：对［SiO2(2.4 nm)/Co(t)］20体系，在Co层厚度小于2.5 nm时，Co层由连续变为不连续；Co层不连续时，其导电机理为热激发的电子隧穿导电，lnR与T-1/2接近正比关系; 隧道磁电阻（TMR）在Co层厚度为1.4 nm时出现极大值-3%.DMIM 的性质 不仅与磁性金属层厚度密切相关，而且与绝缘层厚度有密切的关系.在固定Co层厚度为 1.9 nm的情况下，研究了TMR随SiO2层厚度的变化 关键词： 不连续磁性金属/绝缘体多层膜 隧道磁电阻效应     

Modeling Thin Film Multilayer Broad-Band-Pass Filters in Visible Spectrum

Multilayer thin-film structures have been used to model and analyze the performance of broad-band-pass interference optical filters in visible spectrum. Starting from nine-layer configuration comprising quarter-wave layers, the number of layers is increased to make the pass band smooth with steep slopes and square band-pass characteristics. The layer materials are also varied to improve the performance of the filters. Further, matching layers are also introduced with incident medium and the substrate to reduce the magnitude of ripples in the pass band. Shift in the peak wavelength is also investigated as a function of angle of incidence.     

Preparation and the investigation of its electrochemical and photoluminescent characteristics of organic-inorganic hybrid multilayers containing europium-substituted heteropolytungstate

Photoluminescent multilayers were fabricated by layer-by-layer deposition between europium-substituted heteropolytungstate K₁₃[Eu(SiW₁₁O₃₉)₂]·28H₂O (denoted ESW) and a cationic polymer of quaternized poly(4-vinylpyridine) partially complexed with osmium bis(2,2′-bipyridine) (denoted as QPVP-Os) on glassy carbon and quartz substrates. The resulting photoluminescent organic-inorganic hybrid multilayers were characterized by electrochemical impedance spectroscopy, UV-Vis absorption spectrometry, cyclic voltammetry and photoluminescence spectra. Electrochemical impedance spectroscopy, UV-Vis absorption spectrometry and cyclic voltammetry results demonstrated that the multilayers were regular growth each layer adsorption. The photoluminescent properties of the films at room temperature were investigated to show the characteristic Eu³⁺ emission pattern of ⁵D₀→⁷F_j.