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关键词： Perovskite  

摘要： A one dimensional copper(ii)-based perovskite, (C5H8N3)[CuCl3], was successfully synthesized. XR-diffraction demonstrates that the mineral framework of this perovskite is formed by infinite needle-like chains [CuCl3]-(proportional to), where each Cu2+ ion, with its [4+2] coordination sphere, adopts a nearly tetragonal symmetry. The simultaneous TGA/DSC analyses demonstrate the stability of the material at ambient temperature and up to 130 degrees C. The convergence of the optical experimental results and the theoretical DFT calculations of the electronic structure demonstrates the semiconducting character of the synthesized compound with an experimental direct band gap energy of 2.21 eV. The optical analysis shows that a cooperative Jahn-Teller effect is manifested around the copper ions. Both ligand to metal charge transfer (LMCT) transitions and crystal field transitions (d-d) make the material suitable for green solar cell applications. The magnetic properties of (C5H8N3)[CuCl3] can be described by a model of S = 1/2 antiferromagnetic dimers with exchange interaction J/k(B) = -122.7 K.

关键词： Excitons   Electric fields   Thin films   Absorption   Absorption spectroscopy  

摘要： Two-dimensional (2D) layered MoS2 nanosheets (NSs) possess many unique properties and hold great potential for various applications. Herein, MoS2 NSs were synthesized by a hydrothermal method. The as-synthesized MoS2 NSs are crystalline and layered. Absorption and electroabsorption (E-A) spectra of MoS2 doped in a poly(methyl methacrylate) (PMMA) thin film were measured at different temperatures (290-40 K). The E-A spectra detected at the second harmonic of the modulation frequency of the applied electric field were analyzed using an integral method by considering the Stark effect as a dominant feature. The absorption spectra consist of seven transitions, among which five transitions are contributed to the E-A spectra. It is found that the changes in the electric dipole moment and polarizability of each transition determined at different temperatures increase substantially with decreasing temperature. Electronic resonance states identified for low-energy excitonic bands of MoS(2 )NSs showed prominence E-A signals. The study is essential to understand the electronic structure in the photoexcited state, which is important for applications of MoS2 NSs to optoelectronic devices.

关键词： Guided mode resonance   Near infrared radiation   Optical absorption   Optical sensing   Precision metrology   Resonant modes  

摘要： We propose and experimentally demonstrate high resolution angle sensors based on ultra-narrowband graphene perfect absorbers. Perfect absorption at wavelength of 1452.8 nm with absorption bandwidth of 0.8 nm is numerically demonstrated for a designed angle sensor based on single graphene absorber at normal incidence, and the angular width of the resonant absorption is only 0.05 degrees. In the experiment, peak absorption over 95% with bandwidth about 2.8 nm is measured at normal incidence for a fabricated graphene sensor, and the device has a wavelength-angle sensitivity over 17 nm per degree which agrees well with the simulation result. Meanwhile, an optoelectronic angle sensor with high resolution and fast response by using an array of graphene absorbers is proposed. The demonstrated graphene angle sensors with ultra compact size and high resolution could be of valuable applications in many fields. (C) 2021 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： 光纤光栅   金属化   预应力平台   电阻点焊   温度传感特性  

摘要： 为解决光纤光栅易遭受破损和传感灵敏度不高的问题,设计定制了微型点焊机和预应力平台,先对光纤进行了镀镍金属化,然后采用毛细管式电阻点焊法将光纤封装在毛细钢管中进行保护性封装,并进行了温度传感特性检测。试验结果表明:电镀的镍层表面光亮平滑,光纤与电镀镍层结合紧密;光纤传感器的中心波长与温度变化量之间的拟合线性度很好,可以达到0.999以上;温度灵敏度是裸光栅传感器的2.8倍左右。

关键词： 薄膜   光学薄膜   多光谱掌纹图像采集   滤光片   光谱特性参数   膜系设计  

摘要： 设计了一组应用于多光谱掌纹图像采集系统的光学薄膜滤光片。根据手掌皮肤在可见、近红外光谱波段反射率不同的特点,研究了掌纹识别滤光片的光谱特性参数及膜系设计。为提高系统获得的掌纹图像质量,采用四通道滤光片设计方案,光谱特性参数要求如下:中心波长为λ_(1)=470 nm、λ_(2)=520 nm、λ_(3)=630 nm、λ_(4)=880 nm;各通道的半宽度在8~12 nm范围内,透射率大于90%,平均截止背景深度大于OD6(即光谱透射率T<10^(-6))。

关键词： STEM教育   光的全反射   高中物理   教学设计  

摘要： 基于STEM教育理念和“以学生为中心”的教育思想,以生活场景为基础,融入前沿科技,对光的全反射进行教学设计,从创设情境、协作探究、设计制作及拓展视角等四个方面展开教学,提高学生物理学习兴趣,突出学生主体地位,注重学生全面发展,促进物理学科核心素养落地生根。

关键词： 阅读题   林海音   认真观察   《城南旧事》   期末考试   骆驼   咀嚼   英子  

摘要： 打开林海音奶奶的《城南旧事》,我发现自己早就认识她。有次期末考试,我在阅读题里见过她。我特别羡慕英子,她会在冬阳下,认真观察骆驼咀嚼草料的样子,即使骆驼是"那样丑的脸,那样长的牙,那样安静的态度",英子还是禁不住喜欢,模仿着它们咀嚼的样子。虽然我没有见到过骆驼队,也没有观察过骆驼,但是我们家的母鸡贝贝,我可是很喜欢的!无论是天晴还是下雨,贝贝总是踱着方步,雄赳赳气昂昂地在我们家六楼顶上散步。

关键词： 近代物理实验   声光效应实验   混合式  

摘要： 近代物理实验是一门理论性和综合性很强的专业课程,对物理专业学生的实践能力及创新意识的培养都具有重要的作用。“声光效应实验”是近代物理实验课程的实验项目之一,文中简要分析了实验项目现状与当前网络教学形势,构建了依托线上课程资源进行混合式模式探索的教学策略与方法,阐述了“声光效应实验”采用线上线下混合式教学模式的意义。这为探讨近代物理实验课程的教学改革方法提供了有益的参考。

关键词： 贪婪随机坐标下降法   最快残量下降指标   混合加速算法   Einstein-积   张量方程  

摘要： 贪婪随机坐标下降法是当前提出的求解最小二乘问题的有效方法.本文通过引入“残量最大下降指标”,给出了贪婪随机坐标下降法的修正版本及一个有效的两步混合加速算法.同时.将这些改进的有效算法用来求解带有Einstein-积的张量方程.理论及数值实验都充分验证了所提出算法的可行性和有效性.

关键词： 色温   颜色玻璃   光学薄膜   滤光片  

摘要： 为了得到不同光源色温的辐射谱,提出了基于颜色玻璃和镀膜相结合的方法进行色温变换。以3000 K色温的卤素灯作为标准光源,将其变换成4800 K标准黑体辐射色温,根据目标色温透辐射光谱,选定QB11作为基底,为了进一步修正辐射谱线,选择在QB11基底上镀制光学薄膜。使用Essential Macleod薄膜设计软件设计了以TiO_(2)和SiO_(2)组合的5层膜系,并进行了优化,最终得到膜层厚度为353 nm。实验结果表明,通过颜色玻璃和光学薄膜相结合的方法可有效将标准卤素灯的3000 K色温变换成标准黑体辐射4800 K色温,光谱偏离度质量指数为3.67%。最终的光谱偏离质量指数表明,通过上述方法进行色温变换效果良好。