共查询到19条相似文献，搜索用时 46 毫秒
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磁光学活性与自然光学活性均可用介质对左右圆偏振光的吸收之差来表示 .但自然光学活性和磁光学活性的物理机制是截然不同的 ,前者源于镜象不能互相重叠介质的非定域光学响应 ( nonlocaloptical response) ,而后者则是由于介质的时间反演对称性 ( time- reversal symmetry)被磁场打破所致 .理论分析表明 ,当介质的两种光学活性同时存在时 ,将会出现一个新的附加光学效应 ,这种磁光学活性与自然光学活性之间的交叉效应称为磁手性效应 ( magneto- chiral effect)或磁手二色性 ( magneto-chiral dichroism) [1,2 ] .磁手性效应通常很弱 ,直到 1… 相似文献
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首次报道了以Ｄ－葡萄糖为原料合成新型光学活性葡萄糖衍生类β－氨基醇化合物的新方法，目标化合物：（２Ｓ，３Ｓ）－甲基－２－脱氧－２－苯胺基－４，６－Ｏ－苄叉基－α－Ｄ－吡喃阿卓糖苷（７）经各种分析测试手段证实。 相似文献
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实验构型分析是定量分析和频振动光谱的基础.变换实验构型,不仅要考虑某一振动模式信号强度的大小,还要考虑不同构型下的信号检测效率.现有的和频振动光谱实验构型分析主要考虑前者.本文探讨实验构型分析中所涉及的信号检测效率问题,模拟在共向式和频(差频)及对射式和频(差频)振动光谱实验中选取何种实验构型对采集信号光更加合理有效.利用相干光学过程能量守恒和动量守恒原理,分析了入射角及入射光频率等因素对信号出射角的影响,并模拟了信号出射角与入射角及入射光频率的关系,得到了可选的入射角组合最多、出射角随入射光频率变化最小的实验构型.结果表明,和频振动光谱采取共向式实验构型,差频振动光谱采取对射式实验构型,有利于信号采集,进而有利于用实验构型分析方法对和频(差频)振动光谱进行定量研究. 相似文献
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Following the surface enhanced Raman scattering (SERS), we shall investigate the possibility of observing surface‐enhanced sum‐frequency generation (SESFG), which refers to the transformation of ordinary vibrational SFG (i.e. singly resonant) into SESFG. Two mechanisms of SESFG will be studied; one is due to the transformation of singly‐resonant vibrational SFG into doubly resonant vibrational SFG (that is, both vibrationally resonant and Raman‐scattering resonant) and the other is due to the enhancement of the polarizability in addition to the original vibrational resonance in vibrational SFG. 相似文献
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J. Franzke R.W. Fox L. Hollberg 《Spectrochimica Acta Part B: Atomic Spectroscopy》1998,53(14):1951-1955
High resolution atomic absorption measurements of lead at 283 nm in a vapor cell were performed by frequency doubling an 850 nm laser diode to obtain 425 nm light, followed by sum frequency generation of the harmonic radiation with a second 850 nm laser diode. 相似文献
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Polyimides are widely used as chip passivation layers and organic substrates in microelectronic packaging. Plasma treatment has been used to enhance the interfacial properties of polyimides, but its molecularmechanism is not clear. In this research, the effects of polyimide surface plasma treatment on the molecular structures at corresponding polyimide/air and buried polyimide/epoxy interfaces were investigated in situ using sum frequency generation (SFG) vibrational spectroscopy. SFG results show that the polyimide backbone molecular structure was different at polyimide/air and polyimide/epoxy interfaces before and after plasma treatment. The different molecular structures at each interface indicate that structural reordering of the polyimide backbone occurred as a result of plasma treatment and contact with the epoxy adhesive. Furthermore, quantitative orientation analysis indicated that plasma treatment of polyimide surfaces altered the twist angle of the polyimide backbone at corresponding buried polyimide/epoxy interfaces. These SFG results indicate that plasma treatment of polymer surfaces can alter the molecular structure at corresponding polymer/air and buried polymer interfaces. 相似文献
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采用红外-可见和频振动光谱研究了表面包覆油酸分子的Fe3O4纳米颗粒, 得到了2种实验构型(构型1: 可见光入射角63°, 红外光入射角55°; 构型2: 可见光入射角45°, 红外光入射角55°)和3种偏振组合(ssp, ppp, sps)下的和频振动光谱, 比较了2种实验构型下和频光谱的特征, 通过偏振分析方法对各个光谱峰进行了归属. 相似文献
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Baihui Wang Yimin Bai Jiahui Peng Miaomiao Zhang Weiting Zhang Hongtao Bian Yu Fang 《化学物理学报(中文版)》2024,123(3):398-410
The structure of protein and peptide at interfaces plays a crucial role in various biological processes and technological advancements. Understanding these structures is critical for diagnosing diseases, drug delivery, and developing biomaterials. However, the complexity of these systems and limitations in analytical tools have hindered the in-depth exploration. Despite significant efforts in determining protein structures using advanced techniques like X-ray crystallography and cryo-electron microscopy, the understanding of surface-bound protein structures in real conditions remains relatively limited, posing a current challenge in this field. Vibrational sum frequency generation (SFG) spectroscopy has been developed as a versatile method for elucidating molecular structures of proteins across interfaces. This review is intended to introduce the basic principle of SFG spectroscopy, discuss its current advancements in phase measurement, and showcase recent examples (2021–2023) illustrating SFG’s ability in revealing the molecular structure of peptides and proteins at interfaces. This concise review aims to establish a foundation for future studies and applications exploring different types of peptides and proteins at interfaces using SFG. 相似文献
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Tong Zhang Jesse B. Brown Haley Fisher Mallory Liebes Zhi-Chao Huang-Fu Yuqin Qian Yi Rao 《化学物理学报(中文版)》2024,5(3):376-397
The surface states of photoelectrodes as catalysts heavily influence their performance in photocatalysis and photoelectrocatalysis applications. These catalysts are necessary for developing robust solutions to the climate and global energy crises by promoting CO2 reduction, N2 reduction, contaminant degradation, and water splitting. The semiconductors that can fill this role are beholden as photoelectrodes to the processes of charge generation, separation, and utilization, which are in turn products of surface states, surface electric fields, and surface carrier dynamics. Methods which are typically used for studying these processes to improve semiconductors are indirect, invasive, not surface specific, not practical under ambient conditions, or a combination thereof. Recently, nonlinear optical processes such as electronic sum-frequency generation (ESFG) and second-harmonic generation (ESHG) have gained popularity in investigations of semiconductor catalysts systems. Such techniques possess many advantages of in-situ analysis, interfacial specificity, non-invasiveness, as well as the ability to be used under any conditions. In this review, we detail the importance of surface states and their intimate relationship with catalytic performance, outline methods to investigate semiconductor surface states, electric fields, and carrier dynamics and highlight recent contributions to the field through interface-specific spectroscopy. We will also discuss how the recent development of heterodyne-detected ESHG (HD-ESHG) was used to extract charged surface states through phase information, time-resolved ESFG (TR-ESFG) to obtain in-situ dynamic process monitoring, and two-dimensional ESFG (2D-ESFG) to explore surface state couplings, and how further advancements in spectroscopic technology can fill in knowledge gaps to accelerate photoelectrocatalyst utilization. We believe that this work will provide a valuable summary of the importance of semiconductor surface states and interfacial electronic properties, inform a broad audience of the capabilities of nonlinear optical techniques, and inspire future original approaches to improving photocatalytic and photoelectrocatalytic devices. 相似文献
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CHEN Kaichun ZHENG Xuelian YANG Cuicui TIAN Wei Quan LI Weiqi YANG Ling 《高等学校化学研究》2022,38(2):579-587
In this work, azulene is introduced into nano-graphene with coronene center to enhance the second-order nonlinear optical (NLO) properties. The sum-over-states(SOS) model based calculations demonstrate that dipolar contributions are larger than octupolar contributions to the static first hyperpolarizability(〈β0〉) in most nano-graphenes except those with high symmetry(e.g., a C2v nano-graphene has octupolar contributions ΦJ=3 up to 59.0% of the 〈β0〉). Nano-graphenes containing two parallel orientating azulenes (i.e., Out-P and Out-Ps) have large dipole moments, while their ground state is triplet. Introducing B/N/BN atoms into the positions with a high spin density transfers the ground state of Out-P and Out-Ps to closed-shell singlet, and the Out-Ps-2N has a large 〈β0〉 of 1621.67×10−30 esu. Further addition of an electron donor(NH2) at the pentagon end enhances the 〈β0〉 to 1906.22×10−30 esu. The two-dimensional second-order NLO spectra predicted by using the SOS model find strong sum frequency generations and difference frequency generations, especially in the near-infrared and visible regions. The strategies to stabilize the electronic structure and improve the NLO properties of azulene-defect carbon nanomaterials are proposed, and those strategies to engineer nano-graphenes to be semiconducting while maintaining the π-framework are exten-dable to other similar systems. 相似文献
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Feng Wei Wen-xiu Xia Zhong-jin Hu Wen-hui Li Ji-ying Zhang Wan-quan Zheng 《化学物理学报(中文版)》2016,29(2):171-178
Sum frequency generation vibrational spectroscopy (SFG-VS) is a robust technique for interfacial investigation at molecular level. The performance of SFG-VS mostly depends on the spectral resolution of the SFG system. In this research, a simplified function was deduced to calculate the spectral resolution of picosecond SFG system and the lineshape of SFG spectra based on the Guassian shaped functions of IR beam and visible beam. The function indicates that the lineshpe of SFG spectra from nonresonant samples can be calculated by the Guassian widths of both IR beam and visible beam. And the Voigt lineshape of SFG spectra from vibrational resonant samples can be calculated by the Homogeneous broadening (Lorentzian width) and Inhomogeneous broadening (Guassian width) of vibrational modes, as well as the Guassian widths of both IR beam and visible beam. Such functions were also applied to verify the spectral resolution of the polarization-resolved and frequency-resolved picosecond SFG-VS system which was developed by our group recently. It is shown that the linewidths of IR beams that generated from current laser system are about 1.5 cm-1. The calculated spectral resolution of current picosecond IR scanning SFG-VS system is about 4.6 cm-1, which is consist with he spctral resolution shown in the spectra of cholesterol monolayer (3.5-5 cm-1). 相似文献