共查询到20条相似文献,搜索用时 15 毫秒
1.
V. Crupi M. P. Jannelli S. Magazù G. Maisano D. Majolino P. Migliardo 《Il Nuovo Cimento D》1994,16(7):901-910
Summary An analysis of Rayleigh-wing spectra on two isomers of propanol (C3H7OH) and on two of their Br-based isomorphous systems (C3H7Br) is presented. The performed measurements, over a wide temperature range, allow us to identify two different processes
characterizing the response of both the alcohols. A comparison between the rotational dynamics of the linear normal-propanol
(1-propanol) and the more sterically hindered iso-propanol (2-propanol) is performed. At the same time, the role played by
the H-bond in the associative properties of hydrogenous systems is investigated by comparing the dynamical response of the
two alcohols with that of 1-bromopropane and 2-bromopropane, in which the O−H ?active? sites are replaced by ?inert? bromine
atoms.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
2.
S. Woźniak 《Molecular physics》2013,111(13-14):1975-1982
A static magnetic field, acting on an isotropic medium composed of paramagnetic chiral molecules perpendicular to the propagation direction of the optical beam, is shown to induce an axial differential effect—magnetochiral Rayleigh light scattering. Diamagnetic and paramagnetic contributions to the effect are given in terms of the linear and nonlinear electric dipole, magnetic dipole and electric quadrupole polarizabilities responsible also for natural optical activity, the Faraday effect as well as magnetochiral birefringence. Specific cases are discussed. 相似文献
3.
The propagation dynamics of ultraviolet light filament with Rayleigh scattering in air 总被引:1,自引:0,他引:1 下载免费PDF全文
In this paper we present for the first time the effects of Rayleigh scattering on the long distance propagation of ultraviolet (UV) light filament in air based on the stationary analysis. The simulation results show that the effects of Rayleigh scattering on the propagation of UV laser filaments may not be ignored. These influences are slightly dependent on the laser wavelength. We also compare the UV filament propagations at different input powers in the presence and the absence of the Rayleigh scattering and discuss the mechanisms of power loss and beam defocusing. In the absence of Rayleigh scattering, the filament propagation is determined by the oscillating behaviour of the beam size. In the presence of the scattering, the propagation lengths of filament are close to each other at different initial powers and determined by the Rayleigh scattering. 相似文献
4.
A. Latz M. Letz 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(3):323-343
The theory of light scattering for a system of linear molecules with anisotropic polarizabilities is considered. As a starting
point for our theory, we express the result of a scattering experiment in VV and VH symmetry as dynamic correlation functions
of tensorial densities ρ
lm(q) with l = 0 and l = 2. l, m denote indices of spherical harmonics. To account for all observed hydrodynamic singularities, a generalization of the theory
of Schilling and Scheidsteger [1] for these correlation functions is presented, which is capable to describe the light scattering
experiments from the liquid regime to the glassy state. As a microscopic theory it fulfills all sum rules contrary to previous
phenomenological theories. We emphasize the importance of the helicity index m for the microscopic theory by showing, that only the existence of m = 1 components lead to the well known Rytov dip in liquids and to the appearance of transversal sound waves in VH symmetry
in the deeply supercooled liquid and the glass. Exact expressions for the phenomenological frequency dependent rotation translation
coupling coefficients of previous theories are derived.
Received 3 July 2000 and Received in final form 7 November 2000 相似文献
5.
The Rayleigh light scattering in chalcogenide glasslike alloys of the As-S system is investigated. The velocities of longitudinal hypersound, elasto-optical constants, extinction coefficients, and scattering losses have been determined. It is shown that an increase in the amount of sulfur in alloys leads to an increase in chemical differentiation and, as a result, to an increase in the intensity of Rayleigh scattering and in inherent optical losses.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, 823–826, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date. 相似文献
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C. Dreyfus A. Aouadi R.M. Pick T. Berger A. Patkowski W. Steffen 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(3):401-419
We discuss the hydrodynamic equations which describe the shear dynamics of a liquid composed of anisotropic molecules, both
in its normal and its supercooled phases. We use these equations to analyze 90 depolarized light scattering experiments performed in the supercooled phase of a glass forming liquid, metatoluidine, and
show that the information extracted from this analysis is consistent with independent shear viscosity measurements performed
on that liquid in the same temperature range.
Received 28 April 1998 相似文献
9.
Amorphous materials are ubiquitous and widely used in human society, yet their structures are far from being fully understood. Metallic glasses, a new class of amorphous materials, have attracted a great deal of interests due to their exceptional properties. In recent years, our understanding of metallic glasses increases dramatically, thanks to the development of advanced instrumentation, such as in situ x-ray and neutron scattering. In this article, we provide a brief review of recent progress in study of the structure of metallic glasses. In particular, we will emphasize, from the scattering perspective, the multiscale structures of metallic glasses, i.e., short-to-medium range atomic packing, and phase transitions in the supercooled liquid region, e.g., crystallization and liquid-to-liquid phase transition. We will also discuss, based on the understanding of their structures and phase stability, the mechanical and magnetic properties of metallic glasses. 相似文献
10.
性能优越的Si基高效发光材料与器件的制备一直是Si基光电集成电路中最具挑战性的课题之一.Si基Ge材料不仅与成熟的硅工艺相兼容,而且具有准直接带特性,被认为是实现Si基激光器最有希望的材料.对Si基Ge材料N型掺杂的研究有利于提示出其直接带发光增强机理.本文研究了N型掺杂Si基Ge材料导带电子的晶格散射过程.N型掺杂Si基Ge材料具有独特的双能谷(Γ能谷与L能谷)结构,它将通过以下两方面的竞争关系提高直接带导带底电子的占有率:一方面,处于Γ能谷的导带电子通过谷间光学声子的散射方式散射到L能谷;另一方面,处于L能谷的导带电子通过谷内光学声子散射以及二次谷间光学声子散射或者直接通过谷间光学声子散射的方式跃迁到Γ能谷.当掺杂浓度界于10~(17)cm~(-3)到10~(19)cm~(-3)时,适当提高N型掺杂浓度有利于提高直接带Γ能谷导带底电子占有率,进而提高Si基Ge材料直接带发光效率. 相似文献
11.
Rayleigh scattering room temperature cross-section values of N2, CH4 and SF6 have been obtained between 198 and 270 nm by combining cavity ring-down spectroscopy (CRDS) and pressure ramp measurements. The experimental data have been fitted to a functional representation, describing the ~1/λ4 like behaviour of the Rayleigh scattering cross section over a wide wavelength range. The resulting values are compared with numerical predictions, based on refractive indices and molecular anisotropy data available in the literature. From this, values of molecular volume polarizability αvol and depolarization ratios are derived. It is found that the optical extinction for all three gases is governed by Rayleigh scattering for wavelengths down to 200 nm. No absorption onsets in the specified deep-UV region have been observed. 相似文献
12.
N. I. Shamrov 《Journal of Applied Spectroscopy》2006,73(1):68-78
An extension of the semiclassical model is proposed for superradiant Rayleigh scattering of light from a Bose-Einstein condensate
of dilute atomic gases. In contrast to the familiar models, this model takes into account the fact that the atom may be excited
by the scattered light and may acquire backward recoil momentum. The presented equations are solved analytically for the initial
(linear) stage of the process. The intensity of the scattered light and the efficiency of populating atomic states with different
momentum values are studied as a function of detuning from resonance.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 65–72, January–February, 2006. 相似文献
13.
Chukov VN 《Ultrasonics》2012,52(1):5-11
Oscillations of the Rayleigh wave statistical scattering in the Rayleigh limit are theoretically found. These oscillations are violation of the Rayleigh law of scattering. They are caused by the diffraction of a new form - the extraordinary scattering in the Rayleigh limit, which leads to the different frequency dependencies of the scattering coefficient and thus violates the Rayleigh law of scattering. The fundamental physical conception that a wave does not sense the structure of an irregularity in a long-wavelength scattering, when the wavelength is much greater than the character size of the irregularity, i.e. in the Rayleigh limit, is violated as well. 相似文献
14.
D.W. Mueller Jr. A.L. Crosbie 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,98(3):330-357
The focus of this two-dimensional study is the radially varying intensity emergent from a plane-parallel scattering medium exposed to a collimated, Gaussian laser beam directed perpendicular to the upper surface. The method of analysis is the integral transform technique. Specifically, this work uses the generalized reflection and transmission functions from a previous study to construct the emergent intensity with the use of an inverse Hankel transform. Radially varying backscattered and transmitted intensities are calculated for media with isotropic and Rayleigh scattering phase functions and optical thicknesses that range from 0.125 to 8.0. The behavior of the emergent radiation inside and outside the beam is investigated for both narrow and wide beams. A new integration method is implemented to compute the emergent intensity at the beam center. The emergent intensity at the beam center is used to quantify when a one-dimensional model may be used. As expected, for small optical thicknesses and near the beam the phase function has significant influence, while far from the beam multiple scattering reduces the influence of the Rayleigh phase function. Results from this study will be useful in understanding and interpreting more complicated situations, such as those that include polarization. 相似文献
15.
实用被动调制量子密钥分发系统中分束器存在波长依赖性,窃听者据此攻击分束器,以获取密钥信息并且不被发现,而且光纤中存在瑞利散射导致误码率增大。文中提出波分复用器方案来保障量子密钥分发的安全性,并且通过双波长交叉传递来降低误码率。方案中借助于波分复用器将不同波长的光子进行分离,只对部分波长的光子进行偏振测量,Alice和Bob可以通过公共信道分析误码率和收益,得出是否存在窃听者。 相似文献
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R.M. Pick T. Franosch A. Latz C. Dreyfus 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(2):217-228
We derive expressions for the intensity of the Brillouin polarized spectrum of a molecular liquid formed of axially symmetric
molecules. These expressions take into account both the molecular dielectric anisotropy and the modulation of the local polarisability
by density fluctuations. They also incorporate all the retardation effects which occur in such liquids. We show that the spectrum
splits into a q-independent rotational contribution and q-dependent term, which reflects the propagation of longitudinal acoustic modes. In the latter, the two light scattering mechanisms
enter on an equal footing and generate three scattering channels. We study the influence of the two new channels and show
that they may substantially modify the Brillouin line-shape when the relaxation time of the supercooled liquid and the period
of the acoustic excitation are of the same order of magnitude.
Received 14 August 2002 Published online 4 February 2003
RID="a"
ID="a"e-mail: franosch@hmi.de 相似文献
18.
液相纳米硒微粒的性质及其共振瑞利散射光谱研究 总被引:3,自引:3,他引:0
常温常压下,在0.24 mol·L-1的盐酸介质中,二氧化硒与过量的抗坏血酸(Vc)作用,生成单质硒Se(0),获得含有纳米硒微粒的均匀溶液;采用透射电镜和激光散射技术,测出Se(0)以26~243 nm的球形聚集状态存在,并在470 nm处有最强的共振瑞利散射(RRS),在入射波长2倍和1/2处分别有二级散射(SOS)和倍频散射(MFS),其共振瑞利散射强度ΔI470与Se(Ⅳ)的浓度在2.82×10-9~5.64×10-6 g·mL-1范围内呈线性关系,相关系数为0.997。 相似文献
19.
为了解决瑞利散射光易受米散射和背景杂散光干扰的问题,发展了结合窄线宽激光器、分子过滤器以及像增强器等技术的分子过滤瑞利散射技术。在图像诊断的基础上,依据测量的碘蒸气吸收光谱曲线,对CH4/air预混火焰进行了诊断,获得了密度场和温度场分布。距炉面15 mm火焰中心区域处,分子过滤瑞利散射(FRS)技术测量的温度为1 827 K±84 K,密度为0.19 kg/m3,其测温结果与CARS法的测温结果基本吻合。最后分析了FRS技术测温不确定度。实验表明FRS技术具有较高的信噪比,可以定量测量温度和密度信息,有望应用于超音速燃烧流场、紊流场等复杂流场的诊断。 相似文献
20.
J. Wuttke M. Seidl G. Hinze A. Tölle W. Petry G. Coddens 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(2):169-172
The dynamics of supercooled toluene, studied in a GHz-THz range by incoherent neutron and depolarized light scattering, is
found to be in full accord with mode coupling predictions. Around the susceptibility minimum, neutron spectra are wavenumber
independent and proportional to light scattering data; the fast -relaxation scaling law applies; amplitude and frequency diverge with power laws that extrapolate towards a crossover temperature
K.
Received: 20 June 1997 / Accepted: 3 November 1997 相似文献