曲线距离法的二维光纤光谱弯曲校正

多目标光纤光谱望远镜可以在一次观测中获得大量的不同天体的光谱数据。从天体探测到的光在通过光纤之后，再通过光谱仪狭缝，然后在CCD传感器中成像为二维光谱图；之后经过光纤光谱数据处理系统的一系列软件处理，最终输出可供天文界使用的一维光谱并存储起来。一维光谱是天文学家研究目标天体的主要手段，它是通过处理二维光谱图得到的。以LAMOST为例，望远镜系统在一次观测后首先会得到32幅由250条光纤光谱组成的二维光谱，然后经过一系列的处理得到一维光谱。在这个过程中，会有很多因素影响到最终一维光谱的精确度。比如由于望远镜使用时间的增加，某些元件会产生磨损、老化或变形，使得二维光谱中光纤形状会产生一定程度的弯曲，这种弯曲在二维光谱的两侧表现得尤为明显。在一幅常见的二维光谱中，纵坐标方向代表了抽取的一维光谱的波长方向，横坐标方向代表了抽取的一维光谱的流量方向，这种弯曲形变的产生会影响到之后的波长定标和流量定标，使得抽取的一维谱信息不准确。目前初步的解决办法是通过与定标灯谱的比对来尽量减少其影响。但这样不仅造成了时间和人力的浪费，而且准确率和效率不高。就这一现状，提出了一种基于曲线距离法的思想，将弯曲的二维谱线校直：首先采用灰度重心法将一幅二维光谱中的250条光纤中心轨迹进行定位，将异常点采用稳健的局部回归方法剔除；然后将中心轨迹进行曲线拟合，得到光纤中心轨迹的方程；通过模仿曲线变弯的逆过程，即保持轨迹上两点间的曲线距离不变，再将弯曲的光谱映射到竖直的法线上，完成校直过程。在整个过程中保持各个对应点的灰度值不变，通过边缘处理和插值运算解决产生的像素点稀疏问题。最后采用累加法进行一维谱抽取，并将校直后抽取的一维光谱与未校直抽取的一维光谱进行比对，比对后可发现校直前后在一维光谱的两端差别较大，其差值谱线也说明了这一点。该方法实现了二维光谱的自动校直，大大提高了抽取一维谱的效率和准确性。二维光谱的预处理和校直方法首先在LAMOST数据上进行验证，鉴于多目标光纤光谱望远镜系统原理的相似性，该处理方法也适用于其他的多目标光纤光谱望远镜系统，具有较好的参考和应用价值。     

One-dimensional and two-dimensional nanomaterials for the detection of multiple biomolecules

The complexity of biological samples determines that the detection of a single biomolecule is unable to satisfy actual needs. Moreover, the “false positives” results caused by a single biomolecule detections easily leads to erroneous clinical diagnosis and treatment. Thus, it is important for the homogenous quantification of multiple biomolecules in not only basic research but also practical application. As a consequent, a large number of literatures have been exploited to monitor multiple biomolecules in homogenous solution, enabling facilitating the development of the disease diagnosis, treatment as well as drug discovery. One-dimensional nanomaterials and two-dimensional nanomaterials have special physical and chemical properties, such as good electrochemical properties, stable structure, large specific surface area, and biocompatibility, which are widely used in electrochemical and fluorescent detection of biomolecules. This tutorial review highlights the recent development for the detection of multiple biomolecules by using nanomaterials including one-dimensional materials (1DMs) as well as two-dimensional materials (2DMs).     

On the global attractor of 2D incompressible turbulence with random forcing

This study revisits bounds on the projection of the global attractor in the energy–enstrophy plane for 2D incompressible turbulence [Dascaliuc, Foias, and Jolly, 2005, 2010]. In addition to providing more elegant proofs of some of the required nonlinear identities, the treatment is extended from the case of constant forcing to the more realistic case of random forcing. Numerical simulations in particular often use a stochastic white-noise forcing to achieve a prescribed mean energy injection rate. The analytical bounds are demonstrated numerically for the case of white-noise forcing.     

GaInP/GaAs/Ge三结太阳电池不同能量质子辐照损伤模拟

以GaInP/GaAs/Ge三结太阳电池为研究对象,开展了能量为0.7, 1, 3, 5, 10 MeV的质子辐照损伤模拟研究,建立了三结太阳电池结构模型和不同能量质子辐照模型,获得了不同质子辐照条件下的I-V曲线,光谱响应曲线,结合已有实验结果验证了本文模拟结果,分析了三结太阳电池短路电流、开路电压、最大功率、光谱响应随质子能量的变化规律,利用不同辐照条件下三结太阳电池最大输出功率退化结果,拟合得到了三结太阳电池最大输出功率随位移损伤剂量的退化曲线.研究结果表明,质子辐照会在三结太阳电池中引入位移损伤缺陷,使得少数载流子扩散长度退化幅度随质子能量的减小而增大,从而导致三结太阳电池相关电学参数的退化随质子能量的减小而增大.相同辐照条件下,中电池光谱响应退化幅度远大于顶电池光谱响应退化幅度,中电池抗辐照性能较差,同时中电池长波范围内光谱响应的退化幅度比短波范围更大,表明中电池相关电学参数的退化主要来源于基区损伤.     

Two-dimensional optical coherence tomography for real-time structural dynamical characterization

We present a two-dimensional optical coherence vibration tomography (2DOCVT) system with an ultra-precision displacement resolution of ~0.1 nm that is capable of in site real-time absolute displacement measurement of structural line vibrations. Experimental results of sinusoidal, sweep and impulse vibrations were reported. The key figures of merit such as the 2DOCVT system could obtain fast line vibration measurement without scanning and it also could be used to capture structural modal parameters in one single impulse excitation measurement without any vibration excitation input information, making it attractive for the application in low-frequency vibration measurement and response-only modal analysis.     

利用可见-近红外-中红外超快光谱揭示离子交换法制备的少层MoS2中缺陷介导的载流子动力学

本文结合可见-近红外-中红外瞬态吸收光谱技术对离子交换法制备的少层MoS₂中缺陷介导的载流子动力学进行了详细的解析. 在近红外瞬态吸收光谱中观察到的宽带漂白信号表明少层MoS₂纳米片带隙中分布着大量的缺陷态. 实验结果明确揭示了载流子被缺陷态的快速捕获以及进一步的复合过程，证明带隙中的缺陷态对MoS₂光生载流子动力学过程起着至关重要的作用. 在中红外瞬态吸收光谱中观察到的正信号到负信号的转变进一步证实了在导带下小于0.24 eV处存在被载流子占据的缺陷态. 这些在少层MoS₂纳米片中存在的缺陷态可以作为有效的载流子捕获中心来辅助光生载流子在皮秒时间尺度内完成非辐射复合过程.     

金属Al背电极二维AZO光栅的制备和陷光特性

研究了背电极金属Al膜上二维ZnO:Al光栅的制备及其反射光谱特性.在厚度为300 nm的Al膜上溅射80 nm ZnO:Al薄膜,旋涂AZ5206光刻胶,用波长为325 nm的激光进行光刻制作光栅掩模.采用溶脱-剥离法在Al衬底上制备周期(624~1250 nm)和槽深(100~300 nm)可独立调控的ZnO:Al二维光栅.表面形貌采用原子力显微镜和扫描电镜观察,反射光谱用带积分球的分光光度计测试,双向反射分布函数用散射仪测量.结果表明,300 nm Al膜上织构二维ZnO:Al光栅背电极结构,当光栅槽深为228 nm,周期从624 nm增加到986 nm时,背电极总反射率、漫反射率以及雾度均随光栅周期增大而显著增加,而当周期从986 nm增加到1250 nm时,总反射率、漫反射率以及雾度略有增加.双向反射分布函数测试结果进一步证实了上述实验结果,即随着周期增大,漫反射峰值越大,衍射峰个数也增多.提示背反电极上槽深为228 nm、周期为986 nm的二维ZnO:Al光栅具有较好的散射效果,其中漫反射占总反射的百分比为45%.     

Preparation of two-dimensional molybdenum disulfide for NO2 detection at room temperature

In this work, the two-dimensional MoS₂ film was prepared by sulfuring the molybdenum atomic layer on SiO₂/Si substrate. The reaction temperature, heating rate, holding time and carrier gas flow rate were investigated comprehensively. The quality of MoS₂ film was characterized by optical microscopy, atomic force microscopy, Raman and photoluminescence spectroscopy. The characterization results showed that the optimum synthesis parameters were heating rate of 25 °C/min, reaction temperature of 750 °C, holding time of 30 min and carrier gas velocity of 100 sccm. The MoS₂ gas sensor was fabricated and its gas sensing performance was tested. The test results indicated that the sensor had a good response to both reducing gas (NH₃) and oxidizing gas (NO₂) at room temperature. The sensitivity to 100 ppm of NO₂ was 31.3%, and the response/recovery times were 4 s and 5 s, respectively. In addition, the limit of detection could be as low as 1 ppm. This work helps us to develop low power and integrable room temperature NO₂ sensors.