Author Affiliations
Abstract
1 Center for High Pressure Science and Technology Advanced Research, Beijing 100193, People’s Republic of China
2 Key Laboratory of Weak-Light Nonlinear Photonics, School of Physics, Nankai University, Tianjin 300071, People’s Republic of China
3 College of Chemistry and Materials Science, Hebei University, Baoding 071002, People’s Republic of China
Topochemical reactions are a promising method to obtain crystalline polymeric materials with distance-determined regio- or stereoselectivity. It has been concluded on an empirical basis that the closest intermolecular C⋯C distance in crystals of alkynes, d(C⋯C)min, should reach a threshold of ∼3 Å for bonding to occur at room temperature. To understand this empirical threshold, we study here the polymerization of acetylene in the crystalline state under high pressure by calculating the structural geometry, vibrational modes, and reaction profile. We find d(C⋯C)min to be the sum of an intrinsic threshold of 2.3 Å and a thermal displacement of 0.8 Å (at room temperature). Molecules at the empirical threshold move via several phonon modes to reach the intrinsic threshold, at which the intermolecular electronic interaction is sharply enhanced and bonding commences. A distance–vibration-based reaction picture is thus demonstrated, which provides a basis for the prediction and design of topochemical reactions, as well as an enhanced understanding of the bonding process in solids.
Matter and Radiation at Extremes
2023, 8(5): 058402
上海理工大学光电信息与计算机工程学院, 上海 200093
在满足光谱性能的同时, 能最大化减小 Czerny-Turner(CT)光谱仪光学系统尺寸, 并防止入射光线与衍射光线发生干涉, 创建了完整的结构参量选定体系。提出了光栅方程的变式, 确定了防止入射光线与衍射光线发生干涉的约束条件, 建立了光路结构的数学模型, 确定了各个结构参量的计算公式。在此基础上将参量的确定过程编程简化, 输入系统的分辨率、波长范围、数值孔径值和元件之间最小距离, 即可直接得到光路结构的所有设计参量, 实现了快速通用的 CT光谱仪的设计方法。通过实例验证得到光谱范围 780～1020 nm、分辨率 0.4 nm、体积 54 mm×56 mm×30 mm的光谱系统, 可为其他设计提供参考。
光学设计 光谱仪 Czerny-Turner结构 紧凑 防干涉 optical design spectrometer Czerny-Turner structure compact interference prevention
上海理工大学光电信息与计算机工程学院，上海 200093
由于光谱仪的尺寸限制，微型光谱仪在满足一定光谱范围时，其分辨力往往难以小于0.1 nm。而一些特殊应用场合要求光谱仪不仅具有微小的尺寸，还要求具有极高的光谱分辨力。本文基于Zemax 光学设计软件，通过选择合适的初始结构参数与评价函数，自动优化准直镜、聚焦镜、柱透镜、光栅，以及CCD 间倾角和距离，设计出光谱分辨力高达0.05 nm，尺寸为90 mm×130 mm×40 mm 的Czerny-Turner 结构微型光谱仪。在此基础上优化出8 个光栅倾斜角度，使微型光谱仪光谱分辨力在优于0.05 nm 的同时，波段范围达到了820 nm～980 nm。所设计的光谱仪具有超高的光谱分辨力、微小的外形尺寸与适中的光谱范围等特点。
微型光谱仪 光谱分辨力 Czerny-Turner 结构 micro-spectrometer resolution Czerny-Turner structure Zemax Zemax
1 光电控制技术重点实验室，河南 洛阳 471000
2 航空工业洛阳电光设备研究所，河南 洛阳 471000
3 吉林大学，吉林 长春 130022
4 上海大学，上海 200444
提出了一种基于梯度信息的结构相似性算法改进的红外图像非局部均值滤波方法。传统的非局部均值滤波算法采用欧氏距离度量图像块之间的相似性，因而不能够很好地衡量图像细节和边缘信息，导致滤波后图像模糊失真。针对此问题，采用结构相似性度量（structural similarity，SSIM）算法对欧氏距离进行加权改进，针对普通的SSIM边缘信息评价能力的不足，提出了带有梯度信息的GSSIM算法，实验结果表明本方法在保持非局部均值（Non-Local Means，NLM）滤波算法去噪能力的同时还能够较好地保持图像的边缘和细节信息。
非局部均值滤波 图像梯度 结构相似性度量 红外图像 non-local mean filtering image gradient structural similarity measures infrared image
1 上海理工大学 光电信息与计算机工程院, 上海 200093
2 上海理工大学 教育部光学仪器与系统工程研究中心, 上海 200093
3 上海理工大学 上海市现代光学系统重点实验室, 上海 200093
为了同时满足光谱分辨率、光谱范围、探测器(CCD)上光谱信号覆盖区域要求, 提出一种基于CzernyTurner(CT)结构拉曼光谱仪的综合设计方法, 通过Zemax软件采用逐步手动调节光栅倾斜, 自动优化聚焦镜、柱面镜以及CCD间倾角和距离的方式, 设计出全波段光谱分辨率优于4 cm-1, 光谱波数范围为80~3 967 cm-1, 光学结构尺寸为90 mm×130 mm×40 mm的微型拉曼光谱仪。
拉曼光谱仪 光学设计 CzernyTurner结构 Raman spectrometer optical design Czerny-Turner structure Zemax Zemax
Author Affiliations
Abstract
Center for High Pressure Science and Technology Advanced Research, Shanghai, 201203, PR China
Recently we are witnessing the boom of high-pressure science and technology from a small niche field to becoming a major dimension in physical sciences. One of the most important technological advances is the integration of synchrotron nanotechnology with the minute samples at ultrahigh pressures. Applications of high pressure have greatly enhanced our understanding of the electronic, phonon, and doping effects on the newly emerged graphene and related 2D layered materials. High pressure has created exotic stoichiometry even in common Group 17, 15, and 14 compounds and drastically altered the basic s and p bonding of organic compounds. Differential pressure measurements enable us to study the rheology and flow of mantle minerals in solid state, thus quantitatively constraining the geodynamics. They also introduce a new approach to understand defect and plastic deformations of nano particles. These examples open new frontiers of high-pressure research.
High pressure science and technology Static high pressure Synchrotron X-ray probe Equation of state Matter and Radiation at Extremes
2016, 1(1): 59
