Synthesis and Characterization of Pressure and Temperature Dual‐Responsive Polystyrene Microbeads

A facile approach to the synthesis of pressure and temperature dual‐responsive polystyrene (PS) microbeads with controlled sizes via dispersion polymerization is described. Three different luminophors are selected and directly introduced into the reaction system and thus incorporated into the resultant PS microbeads during polymerization. By manipulating the reaction conditions, including concentrations of the initiator and monomer, polarity of the reaction medium, and injection rate for the monomer, uniform PS microbeads with sizes ranging from 1 to 5 μm are obtained. When a light source centered at 365 nm is used to excite all the luminophors in the PS beads, three distinct and resolvable emission peaks corresponding well with the luminophors are observed. By taking advantage of their sensitive responses to both pressure and temperature, the PS beads can be utilized for quantitative measurements of these two stimulations simultaneously. The PS beads loaded with multiple luminophors have the ability to serve as building blocks for the fabrication of novel sensing and imaging devices and therefore provide a promising strategy for the study of aerodynamics.     

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.     

环境卫星HJlA超光谱成像仪在轨辐射定标及光谱响应函数敏感性分析

环境卫星HJIA搭载的超光谱成像仪HSI是我国第一个对地观测的星载高光谱传感器,针对超光谱成像仪缺乏各通道光谱响应函数这一问题,对传统的反射率基法予以改进,提出一种不使用光谱响应函数的场地定标方法.利用敦煌场地2009年8月定标实验数据,实现超光谱成像仪在轨辐射定标.通过构建不同形状的光谱响应函数,分析光谱响应函数形状对最终辐射定标结果产生的误差.结果表明,利用新提出的场地定标方法可以实现超光谱成像仪绝对辐射定标,除水汽和氧气吸收通道外,光谱响应函数对定标结果的影响小于3%,采用新定标方法得到的定标系数可以满足应用的需求.     

Role of symmetry in the transport properties of graphene nanoribbons under bias

The intrinsic transport properties of zigzag graphene nanoribbons (ZGNRs) are investigated using first-principles calculations. It is found that although all ZGNRs have similar metallic band structure, they show distinctly different transport behaviors under bias voltages, depending on whether they are mirror symmetric with respect to the midplane between two edges. Asymmetric ZGNRs behave as conventional conductors with linear current-voltage dependence, while symmetric ZGNRs exhibit unexpected very small currents with the presence of a conductance gap around the Fermi level. This difference is revealed to arise from different coupling between the conducting subbands around the Fermi level, which is dependent on the symmetry of the systems.     

Instability-free ion acceleration by two laser pulses

We demonstrate the instability-free ion acceleration regime by introducing laser control with two parallel circularly polarized laser pulses at an intensity of I = 6.8 × 10²¹?W/cm², normally incident on a hydrogen foil. The special structure of the equivalent wave front of those two pulses, which contains Gaussian peaks in both sides and a concavity in the centre (2D), can suppress the transverse instabilities and hole boring effects to constrain a high density ion clump in the centre of the foil, leading to an acceleration over a long distance and gain above 1GeV/u for the ion bunches.     

Phase diagram of the A and B phases of superfluid 3He in aerogel

We report the first measurements of the A-B phase transition of superfluid 3He confined within 98% silica aerogel in high magnetic fields and low temperatures. A disk of aerogel is attached to a vibrating wire resonator. The resonant frequency yields a measure of the superfluid fraction rho(s)/rho of the 3He within the aerogel. The inferred rho(s)/rho value increases substantially at the A-to- B transition of the confined superfluid, allowing us to map the A-B phase diagram as a function of field and temperature. At 4.8 bars, the B-T transition curve looks very similar to that in bulk with a simple reduction factor of order 0.45 for both transition field and temperature.     

高压氢激发态之间的受激喇曼散射

本文采用非稳腔输出的XeCl准分子激光,首次观察到高压氢高激发态之间的受激喇曼散射,并讨论了它们产生的条件.     

快冷Fe-Al合金中的原子缺陷弛豫

在多功能内耗仪上用自由衰减和强迫振动方法研究了不同Al含量淬火Fe-Al合金中的两个弛豫型内耗峰.结果显示：P1(180℃)和P2(340℃)两个内耗峰只出现在淬火样品的加热过程中，而在随后的冷却过程中不出现.P1峰是由在α和β(或γ)点阵上的空位组成的最近邻双空位偶极子在应力诱导下的重新取向产生的，其弛豫强度随Al含量非单调地变化，在大约25% Al(原子百分比，以下同)处出现最大值.Al含量较低的Fe-Al合金无     

Design and optimization of with low weakly-coupled few-mode fiber nonlinearity

By investigating the influence of the difference of refractive index between core and cladding （nco - ncl）, normalized frequency （V） and core radius （α） on both the intramodal and intermodal nonlinear coefficients （NCs） respectively, we design a novel weakly-coupled four-mode fiber with low nonlinearity. In general, under the premise of ensuring the low NCs between two non-degenerate modes, this design can reduce the intermodal NCs （〈 0.5 W-l·km^-1） between two degenerate modes and optimizes the parameters of differential group delays （DGDs） and chromatic dispersion. The optimized few mode fiber （FMF） is eligible for transmission and mode de-multiplexing in the receiver.