Soft X‐ray absorption spectroscopy and resonant inelastic X‐ray scattering spectroscopy below 100 eV: probing first‐row transition‐metal M‐edges in chemical complexes

X‐ray absorption and scattering spectroscopies involving the 3d transition‐metal K‐ and L‐edges have a long history in studying inorganic and bioinorganic molecules. However, there have been very few studies using the M‐edges, which are below 100 eV. Synchrotron‐based X‐ray sources can have higher energy resolution at M‐edges. M‐edge X‐ray absorption spectroscopy (XAS) and resonant inelastic X‐ray scattering (RIXS) could therefore provide complementary information to K‐ and L‐edge spectroscopies. In this study, M_2,3‐edge XAS on several Co, Ni and Cu complexes are measured and their spectral information, such as chemical shifts and covalency effects, are analyzed and discussed. In addition, M_2,3‐edge RIXS on NiO, NiF₂ and two other covalent complexes have been performed and different d–d transition patterns have been observed. Although still preliminary, this work on 3d metal complexes demonstrates the potential to use M‐edge XAS and RIXS on more complicated 3d metal complexes in the future. The potential for using high‐sensitivity and high‐resolution superconducting tunnel junction X‐ray detectors below 100 eV is also illustrated and discussed.     

Spin-polarized current and tunnel magnetoresistance in heterogeneous single-barrier magnetic tunnel junctions

Current in heterogeneous tunnel junctions is studied in the framework of the parabolic conduction-band model. The developed model of the electron tunneling takes explicitly into account the difference of effective masses between ferromagnetic and insulating layers and between conduction subbands. Calculations for Fe/MgO/Fe-like structures have shown the essential impact of effective mass differences in regions (constituents) of the structure on the tunnel magnetoresistance of the junction.     

Hydrogenated silicene based magnetic junction with improved tunneling magnetoresistance and spin-filtering efficiency

In this paper, hydrogenation is used for the generation of band gap in silicene and the hydrogenated silicene is then studied for its spintronic application. Upon hydrogenation, silicene transforms into a wide band gap material with a band gap of 3.32 eV. Parameters like magneto-resistance and spin-filtering efficiency of magnetic tunnel junction (MTJ) with CrO₂ as semi-metallic electrodes and hydrogenated silicene as scattering region are found to increase compared to pristine silicene as scattering region. The simulation results show that the magneto-resistance of hydrogenated silicene remains above 85% (higher than the pristine counterpart) for the entire bias range. In addition, the spin-filtering efficiency in hydrogenated silicene reaches a value as high as 96% whereas in case of pristine silicene it remains below 90% for the entire bias range.     

双钙态矿Sr_2Fe_(1-x)Mn_xMoO_6体系的磁性和磁输运性质的研究(英文)

我们用X射线光电子能谱、以及相关的电性和磁性测量研究了Sr2Fe1-xMnxMoO6(0相似文献   

Improved Reversible Zinc Storage Achieved in a Constitutionally Crystalline-Stable Mn(VO3)2 Nanobelts Cathode

Rechargeable zinc-ion batteries (ZIBs) are potential for grid-scale applications owing to their safety, low price, and available sources. The development of ZIBs cathode with high specific capacity, wide operating voltage window and stable cyclability is urgently needed in next-generation commercial batteries. Herein, we report a structurally crystalline-stable Mn(VO₃)₂ nanobelts cathode for ZIBs prepared via a facile hydrothermal method. The as-synthesized Mn(VO₃)₂ exhibited high specific capacity of 350 mAh g⁻¹ at 0.1 A g⁻¹, and maintained a capacity retention of 92 % after 10,000 cycles at 2 A g⁻¹. It also showed good rate performance and obtained a reversible capacity of up to 200 mAh g⁻¹ after 600 cycles at 0.2 A g⁻¹ under −20 °C. The electrochemical tests suggest that Mn(VO₃)₂ nanobelts impart fast Zn²⁺ ions migration, and the introduction of manganese atoms help make the structures more indestructible, leading to a good rate performance and prolonged cycle lifespan.     

Study on the nanoscale current of ZnO film by photoassisted peak force tunnel atomic force: A novel technique for UV detection

ZnO film-based ultraviolet (UV) detector was fabricated by photoassisted peak force tunnel atomic force (PFTUNA) on fluorine tin oxide (FTO) substrate. The PFTUNA current in dark and in UV light was ~0.1 and 2.0 nA, respectively. The UV sensitivity (photocurrent/dark current) is more than 20. The response time and the recovery time are ~0.12 and 0.32 s, respectively. The UV sensing mechanism is that the holes will transport to the ZnO surface to capture the adsorbed oxygen ions to weaken the depletion layer under UV illumination. The PFTUNA current between the tip and the ZnO film is consistent with the Richardson–Schottky (RS) thermionic emission model.     

公路隧道围岩稳定性评价的改进人工神经网络方法

本文运用改进的人工神经网络方法 ,研究了公路隧道围岩稳定性的评价定级问题 .首先讨论了模型建立和算法选择与分析 ,并对实际的工程问题进行了计算和模拟 .所得的评价定级结果接近于实际 ,计算方法可靠 ,计算时间适中 ,方法稳定性良好 .本文的研究结果表明 ,利用人工神经网络方法评价隧道围岩的稳定性具有广阔应用前景 .     

Driver gas contaminationin a detonation-driven reflected-shock tunnel

A computational study has been carried out to examine the effects of driver gas contamination in the NASA HYPULSE facility at GASL when operating with a detonation driver in reflected-shock tunnel mode. Unlike high-enthalpy shock tunnels which use helium as a driver gas, the driver gas in a detonation driver consists of a mixture of water vapour and argon, which has very different chemical and thermodynamic properties than those of helium. The purpose of the present work is to quantitatively evaluate the effects of driver gas contamination on the flow properties in the test section. Two computational analyses have been performed. The first analysis examined the nozzle flow under the influence of a prescribed level of driver gas contamination. In the second analysis, the transient development of the driver gas leakage in the reflected-shock region in the shock tube is studied. The unique flow features brought about by the detonation-driver gas and the method for detecting the contamination are discussed.Received: 6 August 2002, Revised: 22 September 2003, Published online: 10 February 2004Correspondence to: R.S.M. ChueAn abridged version of this paper was presented at the 23rd International Symposium on Shock Waves at Fort Worth, Texas, July 23 to 27, 2001     

等熵轻质活塞风洞中活塞质量对匹配压力振荡的影响

等熵轻质活塞风洞的管道中被压缩的气体是作为实验段的气源，在实验阶段，要求其压力维持恒值，称此压力为匹配压力，这一条件只有在忽略活塞质量的理想情况下才可实现，本文研究在实际情况下，即考虑活塞质量时，质量对匹配压力振荡的影响，从而得出活塞质量的选择范围。