圆二色性对旋光现象的影响

分析了旋光活性物质的圆二色性对旋光现象的影响 ,给出了一种测量介质圆二色性的方法。     

氯酸钠晶体的CD光谱及ORD特性研究

用标准水溶液法生长出氯酸钠晶体,并通过切割、抛光,获得了尺寸为10.9 mm×8.2 mm×4.7mm的透明、规则的氯酸钠晶体.沿六个垂直晶体表面的方向对氯酸钠晶体进行了圆二色性CD光谱及UV光谱的测定,同时采用自制的旋光色散仪对其在上述6个方向的旋光色散特性进行了研究.首次从实验上证实,在紫外区域,氯酸钠晶体在各个方向上均表现出相同的圆二色性;在可见光区域,氯酸钠晶体在各个方向上均表现出相同的旋光色散特性,这一现象与另外一种手性晶体水晶显然是不同的.     

NYAB晶体的COTTON效应和旋光度估算

本文报道了ＮＹＡＢ［四硼酸铝钇钕，Ｎｄ，Ｙ１－ｘＡｌ３（ＢＯ３）４］在室温下，３００－８００ｎｍ波长范围内晶体Ｚ轴方向的ＣＤ谱（圆二色性谱）测定的结果，给出了相应的Ｃｏｔｔｏｎ效应参数。将Ｋｒｏｎｉｇ－Ｋｒａｍｅｒｓ变换公式应用于晶体，在高斯型ＣＤ带近似下，给出了晶体旋光度与Ｃｏｔｔｏｎ效应参数的关系式。计算了ＮＹＡＢ晶体Ｚ轴方向的旋光度，讨论了在ＣＤ带半宽较小时用ＣＤ谱的测量估算晶体旋光度的优点     

法拉第效应实验装置中光路的设计

根据目前多数法拉第效应实验装置没有磁致旋光与自然旋光区别的实验功能，设计了特殊的光路．实现了磁致旋光和自然旋光的区分，且光路调节容易．现象直观清晰．     

磁致旋光增强效应与微量样品旋光检测方法

微流控光学检测系统的微型化和集成化是微流控技术的发展趋势,微量液体物质的旋光检测也是微流控光学技术的重要研究课题之一.分析了内含磁致旋光介质的旋光反射腔的偏光特性,理论预言这种旋光反射腔具有旋光增强效应,在此基础上提出了微量样品的旋光增强检测方法和器件设计原理.研究结果表明,该方法可以在小光程限制条件下显著提高磁旋光介质的检测灵敏度.在不考虑样品吸收的情况下.旋光增强法与普通消光法的检测灵敏度之比的极限约为78.5.该方法可以应用于微流控系统的旋光检测以及实现磁旋光仪器的小型化和微型化.     

基于不同波长的光对葡萄糖溶液旋光色散的研究

通过不同波长的光源照射葡萄糖水溶液,观察到旋光现象,并测出了不同波长所对应的旋光度,从而计算出它们的旋光率。通过分析测量数据得,在一定温度下葡萄糖溶液旋光率与波长具有对应的函数关系,证实了旋光率与照射光源波长倒数的平方成正比。     

磁旋光增强效应与旋光增强器特性分析

根据法拉第磁光效应的非互易性,分析了旋光反射腔的光强输出特性,表明这种反射腔具有旋光增强效应.在此基础上提出了用于检测微小旋转角的旋光增强法,并对旋光增强器的特性进行了理论分析和仿真计算.给出了测量灵敏度随器件反射率、样品吸收因素及一次旋光角变化的关系,讨论了角度测量工作点、测量范围以及相对灵敏度理论极限问题.旋光增强器有望应用于微流控系统的旋光检测以及实现磁旋光仪器的小型化和微型化. 关键词： 法拉第磁光效应 磁旋光增强 微小旋光角检测 微流控系统     

ε′对旋光光纤特性影响的理论分析与计算

通过对旋光光纤基本理论的讨论，以ε′为自变量为旋光光纤的基本参量和电磁场分量进行了数值分析，得出了相应的计算图表，另外，通过对实际的旋光光纤进行旋光角测量和进一步分析，论证了ε′与偏置磁场之间具有简单而明确的线性关系。这使得原本复杂的张量介电常量矩阵的求解变得非常简单。     

旋光晶体的寻常折射率与左旋光和右旋光折射率的关系

由光的波动方程证明,若介质为旋光物质,则其极化率张量χ一定有非对角对称的共轭虚元素,并导出了旋光晶体的寻常折射率no与左旋光折射率nL和右旋光折射率nR之间的关系.将理论分析结果与实验数据相对照,结果完全吻合.     

手性介质中椭圆偏振光诱导非线性旅光的表征

给出了方便实用的计算非线性旋光角Δθ的公式,在理论上分析了非线性旋光角随椭圆特征参量改变的变化规律,给出了数值模拟的结果,并针对具体手性材料与放射光强估算了非线性旋光角的量级。     

Second-harmonic generation circular dichroism spectroscopy from tripod-like chiral molecular films

The second-harmonic generation (SHG) circular dichroism in the light of reflection from chiral films of tripod-like chiral molecules is investigated.The expressions of the second-harmonic generation circular dichroism are derived from our presented three-coupled-oscillator model for the tripod-like chiral molecules.Spectral dependence of the circular dichroism of SHG from film surface composed of tripod-like chiral molecules is simulated numerically and analysed.Influence of chiral parameters on the second-harmonic generation circular dichroism spectrum in chiral films is studied.The result shows that the second-harmonic generation circular dichroism is a sensitive method of detecting chirality compared with the ordinary circular dichroism in linear optics.All of our work indicates that the classical molecular models are very effective to explain the second-harmonic generation circular dichroism of chiral molecular system.The classical molecular model theory can give us a clear physical picture and brings us very instructive information about the link between the molecular configuration and the nonlinear processes.     

All-silicon chiral metasurfaces and wavefront shaping assisted by interference

Chiral metasurfaces have different electromagnetic responses with circularly polarized lights, showing as circular dichroism and optical activity. Here, a novel kind of all-silicon chiral metasurface is proposed by introducing destructive interference between achiral meta-atoms. The maximum value of circular dichroism spectra can reach 0.49. By adding an antireflective layer at the side of the silicon substrate, the maximum circular dichroism reaches 0.54. What is more, the bandwidth of circular dichroism greater than 0.4 reaches 0.15 THz. Two samples are fabricated to verify the feasibility of this scheme, and the experimental results are in good agreement with the simulations. In addition, the proposed scheme can also be used to generate various interesting functions, such as beam control and vortex generator. This flexible and efficient implementation solution of chiral metasurface can bring new ideas to the development of chiral devices in the future.     

On the possibility of determining anthracycline antibiotics in aqueous solutions using optical analytical system (biosensor)

We propose a version of the theory describing the circular dichroism spectra of cholesteric liquidcrystal dispersion particles of double-stranded DNA. The basis of the theory is the concept of absorption of electromagnetic waves by large molecular systems. The effect of physical parameters of dispersion particles on their circular dichroism is theoretically determined. It is experimentally demonstrated that circular dichroism can be used as a convenient tool for creating an optical analytical system for the determination of biologically active compounds that interact with DNA molecules.     

Opus musicum

The rotation of the plane of linearly polarized light by an optically-active medium arises from a difference between the refractive indices of the medium for left- and right-circularly polarized light. The circular birefringence is related to a circular dichroism, which is exhibited by all molecules which are not superposable on their mirror image and exist as laevo- and dextro-rotatory isomers. The circular dichroism of a dissymmetric molecule in a particular absorption region originates from an electronic transition with collinear electric and magnetic dipole moments, corresponding to the displacement of a molecular valency electron through a helical path by the absorption of radiation. The right- or left-handed form of the helical path depends upon the molecular structure, and the absolute stereochemical configuration of dissymmetric molecules may be determined by comparing their circular dichroism spectra with the calculated rotational strengths. In addition the polarization direction of an electric moment and the magnitude of a magnetic moment of an electronic transition in a dissymmetric molecule may be derived from circular dichroism measurements.     

X-ray dichroism in biaxial gyrotropic media: Differential absorption and fluorescence excitation spectra

The differential absorption and the differential change in the polarization state of an X-ray beam propagating inside a gyrotropic crystal are described using a Müller matrix, the 16 elements of which are related to the anisotropic components of the multipolar polarizability tensors at the absorbing site. Analytical expressions are given up to third order for X-ray linear and circular dichroism, X-ray optical rotation and X-ray circular polarimetry in transmission. The same formalism is extended to discuss Fluorescence detected dichroism spectra with or without polarization analysis of the fluorescence. Fluorescence detected dichroism is strictly proportional to dichroism measured in the transmission geometry only for uniaxial crystals. In biaxial crystals, the tiny effects of X-ray gyrotropy are swamped by large linear dichroism signals due to the imperfect polarization transfer function of Bragg monochromators. Second order effects should also be taken into consideration. Our general formulation of linear and circular dichroism includes terms of odd parity with respect to the action of the time reversal operator: such terms cannot contribute to natural dichroism but can be activated by a magnetic field. The terms responsible for X-ray magnetic circular dichroism are well known but non-reciprocal X-ray gyrotropy effects are also predicted in magnetic crystals of appropriate symmetry. Received 3 March 1999     

A picosecond time-resolved vibrational circular dichroism spectrometer

We present an experimental setup to detect transient vibrational circular dichroism signals. A femtosecond laser system is synchronized to a photoelastic modulator to produce alternating left- and right-handed circularly polarized mid-IR pulses at 1 kHz repetition rate. Transient changes in the circular dichroism of the CH-stretch vibrations of a cobalt-sparteine complex were probed in a proof-of-principle experiment and are clearly distinct from conventional transient absorption changes.     

Novel pressure-induced magnetic transition in magnetite (Fe3O4)

Fe K-edge x-ray magnetic circular dichroism of magnetite (Fe3O4) powders was measured with synchrotron radiation under variable pressure and temperature conditions in diamond anvil cell. The magnetic dichroism was observed to decrease discontinuously by approximately 50% between 12 and 16 GPa, independent of temperature. The magnetic transition is attributed to a high-spin to intermediate-spin transition of Fe2+ ions in the octahedral sites and could account for previously observed structural and electrical anomalies in magnetite at this pressure range. The interpretation of x-ray magnetic circular dichroism data is supported by x-ray emission spectroscopy and theoretical cluster calculations.     

傅里叶变换红外光谱与圆二色光谱表征磷脂酶D二级结构的比较

报道了傅里叶变换红外光谱与圆二色光谱光学信息表征蛋白质二级结构的比较,研究表明傅里叶变换红外光谱与圆二色光谱光学信息表征蛋白质二级结构时,要注意缓冲体系的选择,磷酸盐缓冲液比醋酸盐缓冲液更适合使用,利用FTIR与CD光谱信息表征蛋白质二级结构,两者的数据吻合较好。     

Instrument for determining the polarization state of reflected and transmitted light

An instrument is described which enables the state of polarization of a light beam to be found. It is discussed with reference to studies of optical rotation, circular dichroism and conventional ellipsometry. The main features are that it records automatically and allows the azimuth and ellipticity of an elliptically polarized beam to be measured simultaneously over a wide wavelength range. The performance is illustrated by spectra showing the optical rotation and circular dichroism of an octahedral cobalt lll species.     

Experimental evidence of third-order nonlinear dichroism in a liquid of chiral molecules

We present experimental evidence of the existence of a nonlinear circular dichroism in a liquid of chiral molecules. This effect is demonstrated by a light-induced circular dichroism on two enantiomeric RuTB [ruthenium(II) tris(bipyridyl)] samples after a careful analysis of the impact of the third-order nonlinear response on the optical activity of the system. These experimental results are in good agreement with a previous theoretical investigation.