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为了测定钽酸锂铁电晶体异常声子的方向色散,我们找到一种较为满意的直角散射几何配置,制备了十个不同取向的样品,并为消除内反射光引起的附加散射,在样品表面上镀了增透膜,获得了波夫与光轴成不同夹角时的一系列寻常声子和异常声子的喇曼光谱.对这些喇曼光谱进行了识别,认定了四个A_1光学声子和九个E光学声子,确定了十三个异常声子方向色散支.由于全部异常声子的散射峰能始终一起出现在同一喇曼光谱中,使得异常声子方向色散的确定一目了然.最后用单轴晶体异常声子方向色散公式计算了异常声子的方向色散曲线,实验与理论计算相当符合. 相似文献
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依来铬青R-蛋白质体系的共振光散射特征及微量蛋白质的光散射法测定 总被引:2,自引:1,他引:1
基于蛋白质对有机染料依来铬青R共振光散射的增强作用 ,拟定了一种测定蛋白质的共振光散射法。在pH 4 0的酸性介质中 ,依来铬青R在 4 0 0nm处的共振光散射增强与蛋白质浓度呈线性关系 ,对牛血清白蛋白 ,测定的线性范围为 0~ 5 0mg·L-1 ,检测限 4 4 4 μg·L-1 。该方法简便 ,快速 ,灵敏 ,稳定性及选择性好 ,用于人尿样品中蛋白质含量的测定 ,结果满意 相似文献
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在酸性缓冲溶液中,阴离子表面活性剂十二烷基苯磺酸钠SDBS能与金鸡纳类生物碱药物体系中一对对映异构体QN和QD作用产生增强的同步光散射(synchronous light scattering,SLS)信号,本文首先利用偏振同步光散射(polarized synchronous light scattering)信号,建立了同步光散射偏振度(P)区分QN和QD这对对映异构体,同时利用同步散射光谱和双标准曲线计量分析法对2种金鸡纳类生物碱药物进行同时测定,并将该方法应用于尿样中QN和QD的同时测定,结果令人满意。 相似文献
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中性红共振光散射法测定脱氧核糖核酸 总被引:10,自引:0,他引:10
本文基于脱氧核糖核酸 (DNA)对有机染料中性红的共振光散射的增强效应 ,拟订了一种测定DNA的共振光散射法。在pH 5 0~ 7 0范围内 ,有机染料中性红在DNA分子表面进行长距组装导致共振光散射增强。在 335 0nm处的共振光谱散射增强程度与DNA浓度呈线性关系 ,其线性范围为 0~ 6 0 0ng·mL-1,检出限可达 12 8ng·mL-1。该方法简便、快速 ,具有较高的灵敏度和准确度。将该方法用于混合样品中DNA的测定 ,结果令人满意。 相似文献
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吴有训氏最近对于多原子气体散射线之理论,曾作详尽的探讨。吴氏得到一个公式,表示由多原子气体所散射之强度,其中一部为相干的散射,另一部为不相干的散射。以前关于多原子气体散射X-线之实验,为数甚少,且为定性的结果。最近美人Wollan,对于由O_2及N_2(双原子气体)所散射钼的K_3α线之强度,曾作绝对的度量。Wollan的结果,与吴有训氏的理论,甚属相符。本篇目的,在测定由Cl_2,CO_2,N_2O,H_2S,CCl_4及CHCl六种气体所散射X-线之强度,每一实验,均与由0_2者互相比较,根据Wollan的结果,每种气体所散射之绝对强度,皆一一量得。所用之入射X-线为钼之Kα线,系藉Ross的平衡过滤法分出。强度之测量,系用一游离方法。散射角度的范围,自15度至130度。每种气体的实验结果,均与吴氏的理论,互相比较,证明理论与实验,甚属相符。在计算时,原子的“构造因数”,系由Hartree的方法算得,一分子中两原子的相隔距离,则由带光谱的结果推得。 相似文献
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X—射线荧光分析散函数法的原理及其应用:—Ⅲ.连续背景幂?… 总被引:1,自引:0,他引:1
本文在宽的基体变化范围内对波长为0.081nm的连续散射X-射线进行了研究,表明质量衰减系数与连续散射强度之间不再遵守传统散射内标法所假定的反比例关系,而是呈一种幂函数关系。理论证明和实验结果一致。提出了用0.081nm处的散射强度的函数校正基体效应的方法,用于地质样品中微量锶的测定,结果显示,在较大的基体变动范围内,本不与传统散射内标法相比准确度提高近4倍,克服了传统方法适应基体变化范围小的缺点 相似文献
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万勇韩文娟贾明辉云茂金郭月孙蕾 《光学学报》2015,(3):136-144
选取高品质因数的圆弓形散射元微腔构建耦合波导,通过改变散射元参数和耦合腔散射元平移等方法,得出光子晶体耦合腔波导结构的慢光变化规律,并实现很好平带下的极高群折射率。模拟结果显示,不同微腔个数的耦合波导,通过调整短轴/长轴之比和散射元平移等方式,不仅可以获得各种平带慢光曲线,还可以获得群折射率从4.10×104到1.35×105的超低慢光结构。 相似文献
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本文在宽的基体变化范围内对波长为0.081 nm的连续散射X-射线进行了研究,表明质量衰减系数与连续散射强度之间不再遵守传统散射内标法所假定的反比例关系,而是呈一种幂函数关系.理论证明和实验结果一致.提出了用0.081 nm处的散射强度的函数校正基体效应的方法,并用于地质样品中微量锶的测定,结果显示,在较大的基体变动范围内,本法与传统散射内标法相比准确度提高近4倍,克服了传统方法适应基体变化范围小的缺点. 相似文献
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P. Andreazza H. Khelfane O. Lyon C. Andreazza-Vignolle A. Y. Ramos M. Samah 《The European physical journal. Special topics》2012,208(1):231-244
As atomic structure and morphology of particles are directly correlated to their functional properties, experimental methods probing local and average features of particles at the nanoscale elicit a growing interest. Anomalous small-angle X-ray scattering (ASAXS) is a very attractive technique to investigate the size, shape and spatial distribution of nanoobjects embedded in a homogeneous matrix or in porous media. The anomalous variation of the scattering factor close to an absorption edge enables element specific investigations. In the case of supported nano-objects, the use of grazing incidence is necessary to limit the probed depth. The combination of grazing incidence with the anomalous technique provides a powerful new method, anomalous grazing incidence small-angle X-ray scattering (AGISAXS), to disentangle complex chemical patterns in supported multi-component nano-structures. Nevertheless, a proper data analysis requires accurate quantitative measurements associated to an adapted theoretical framework. This paper presents anomalous methods applied to nanoalloys phase separation in the 1–10 nm size range, and focuses on the application of AGISAXS in bimetallic systems: nanocomposite films and core-shell supported nanoparticles. 相似文献
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利用Mie散射与反常衍射理论的数值计算,对球形颗粒Mie散射和反常衍射作了大量详细的计算和分析比较,提出了相对折射率趋近于1的颗粒的反常衍射近似替代Mie散射的判据。 相似文献
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A detailed analysis of X-ray scattering intensity of electrodeposited amorphous nickel-phosphorus alloys has been carried out by X-ray diffraction with anomalous scattering technique. The scattering powers of these alloys were changed by the anomalous scattering of nickel atom for molybdenum, copper and cobalt radiations and the three partial structure factors required to characterize a binary disordered alloy were estimated. It is found that the partial structure factors are approximately independent of the concentration of alloys and the partial structure factors of Ni-Ni and Ni-P pairs contribute mainly to the splitting of the second peak in the total structure factor directly obtained from experiments. 相似文献
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A. Belafhal M. IbnchaikhK. Nassim 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,72(4):385-402
This work is devoted to a theoretical study of scattering of light by absorbing and nonabsorbing oriented spheroidal particles in the Wentzel-Kramers-Brillouin (WKB) approximation. Within the framework of the scattering theory, we investigate the form factor and the scattering amplitude for this approximation. The Rayleigh-Gans-Debye theory (RGD), the diffraction approximation (DA), and the anomalous diffraction (AD) are treated as particular cases for nonabsorbing spheroids. To illustrate our formalism, we analyze some numerical examples. 相似文献
15.
Phasing of lysozyme using one-wavelength anomalous scattering of sulphur atoms through the combination of direct methods and density modification
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A new method of combining one-wavelength anomalous scattering (OAS) phasing and density modification has been described, in which the improved phases from density modification axe re-introduced into OAS phasing. In this way, the phases could be improved iteratively until convergence. The OAS phasing method is based on the previously established sign-probability formula, which breaks the phase ambiguity in the OAS phasing. The implementation of this method has been available in CCP4 as OASIS. This method, although based on direct-methods, could also incorporate known phases and figures of merit into its sign-probability formula. In the implementation of OASIS, the known phases axe from the positions of the anomalous scatters. In the current method, the known phases are from the density modification. The current method was tested on phasing a lysozyme crystal using anomalous scattering of sulphur atoms with diffraction data collected on an in-house x-ray source. The resulting map was well connected for the backbone atoms and clearly traceable, with an average map correlation coefficient of 0.6622 for the backbone atoms. 相似文献
16.
《Physics letters. A》2005,335(4):327-336
Experimental data shows anomalously large ultra cold neutrons (UCN) reflection losses and that the process of UCN reflection is not completely coherent. UCN anomalous losses under reflection cannot be explained in the context of neutron optics calculations. UCN losses by means of incoherent scattering on material defects are considered and cross-section values calculated. The UCN capture cross section on material defects is enhanced by a factor of 104 due to localization of UCN around defects. This phenomenon can explain anomalous losses of UCN. 相似文献
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Sandra Jacquier 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(5):789-810
The anomalous diffraction (AD) method has proved to be an adequate approximation of the exact method (GMM code computed by Xu) to obtain the scattering cross section for aggregates whose primary particle size parameter is greater than 2. Indeed, the error of this approximated method is less than approximately 10% when the primary particles are in SiO2.However, this method is strongly related to the aggregate morphology since it includes in its formulation the concept of chord length. We initially studied the chord distribution for various aggregates, and then we reformulated the anomalous diffraction method, to approximate the scattering cross section, now completely analytically. This new expression is entitled ADr with the r for rapid because this one is at least a hundred times faster than the standard AD method. 相似文献
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Petr Chylek Julius Zhan R. G. Pinnich 《International Journal of Infrared and Millimeter Waves》1993,14(11):2295-2310
Fluffy snow flakes are modeled by a polydispersion of hexagonal plates for which analytical expressions for absorption and scattering coefficients are derived using the anomalous diffraction approximation. Comparison with results obtained using the dipole superposition method demonstrates that the accuracy of the anomalous diffraction approximation is within 15%. We also show that replacement of hexagonal plates by equal volume or equal surface area spheres leads to large errors in both scattering and extinction cross sections. 相似文献
20.
G. Tateishi G. Bergmann 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,73(2):155-160
Two atomic layers of Ni condensed onto Pb films behave, according to anomalous
Hall effect measurements, as magnetic dead layers. However, it has been
observed that sub-monolayers of Ni lower the superconducting transition
temperature of the Pb film. This has lead to the conclusion that the Ni atoms
are still very weakly magnetic and that their magnetic scattering causes the
reduction of the transition temperature. In the present paper the electron
dephasing due to the Ni has been measured by weak localization. The dephasing
is smaller by a factor 100 than the Tc-reduction would suggest. This
proves that the Tc-reduction in the PbNi films is not due magnetic Ni moments. 相似文献