共查询到20条相似文献,搜索用时 0 毫秒
1.
A. Ben-Amar Baranga;R. Battesti;M. Fouché;C. Rizzo;G. L. J. A. Rikken 《Europhysics letters》2011,94(4)
We report the observation of the inverse Cotton-Mouton effect (ICME) i.e. a magnetization induced in a medium by non-resonant linearly polarized light propagating in the presence of a transverse magnetic field. We present a detailed study of the ICME in a TGG crystal showing the dependence of the measured effect on the light intensity, the optical polarization, and on the external magnetic field. We derive a relation between the Cotton-Mouton and inverse Cotton-Mouton effects that is roughly in agreement with existing experimental data. Our results open the way to applications of the ICME in optical devices.https://doi.org/10.1209/0295-5075/94/44005 相似文献
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Thomas Wriedt 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(11):833-1653
In aerosol science today light scattering simulations are regarded as an indispensable tool to develop new particle characterization techniques or in solving inverse light scattering problems. Light scattering theories and related computational methods have evolved rapidly during the past decade such that scattering computations for wavelength sized nonspherical scatterers can be easily performed. This significant progress has resulted from rapid advances in computational algorithms developed in this field and from improved computer hardware.In this paper a review of the recent progress of light scattering theories and available computational programs is presented. We will focus on exact theories and will not cover approximate methods such as geometrical optics. Short outlines of the various theories are given alongside with informations on their capabilities and restrictions. 相似文献
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表面分形球、柱的光散射 总被引:2,自引:0,他引:2
分形和分维是近些年才兴起的一门处理复杂事物的新方法 ̄[1]。本文主要研究具有表面分形的球、柱的光散射特征。我们首先利用几何光学近似研究了一种表面满足自仿射原理的分形均匀球的散射,其散射特性与分维存在一定的关系。我们还利用微扰法讨论了表面具有沟槽的分形柱的光散射的分形特征。 相似文献
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Krzysztof Knast 《Physica A》1996,230(3-4):388-408
We calculate the effect of magnetic dipolar transitions, related with the polarizabilities B″,
′,
and
″ and electric-quadrupole transitions, related with the polarizabilities C′,
″,
and
′, on dynamical Rayleigh light scattering by isotrophic media. To this aim, we introduce molecular scattering factors of the fourth, fifth and sixth orders related with these polarizabilities. For molecules with 76 magnetic point group symmetries these transitions are found to affect the time-dependent intensities and depolarization ratios of scattered light. Among the 76 groups, the molecules belonging to 23 groups exhibit natural (transmission and Rayleigh) optical activity, whereas the point group
m shows Rayleigh activity only. The effects in question result moreover from the contribution of magnetic-dipole and electric-quadrupole transitions. For isotropic molecules, the above transitions lead to partial depolarization of the scattered light wave. Our use of i- and c-tensors as well as Hermitian and anti-Hermitian components permits the extension of our discussion to regions of absorption as well as cases of full symmetry of the molecules. 相似文献
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O. Merchiers J.M. Saiz 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,101(3):383-393
We study the probability density function of the statistical fluctuations of the intensity scattered by an aggregate freely floating in space and constituted by Rayleigh particles under the dipole approximation. Its evolution as a function of the optical properties of the particles (polarizability) and their separation distance is analyzed. Aggregate geometries with two and three particles will be considered. The influence of the multiple scattering effect on the statistics of the scattered intensity is especially studied. 相似文献
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Wei-Xing Xu 《Optics & Laser Technology》2004,36(2):155-162
A concept of concentration gradient induced by incident radiation which describes the dependence of the Rayleigh (Iω) and hyper-Rayleigh (I2ω) intensities on the power as well as background concentration is proposed. In our previous paper, we have demonstrated the effect of concentration gradient on the first-, second- and third-order polarizabilities and discussed that concentration gradient in the system can be created in a different way. Here we demonstrate the most important origin of the concentration gradient in a system, i.e., the concentration gradient generation by the incident radiation. The formulae developed here can be applied to describe the optical behaviour of solution and gas-phase systems. 相似文献
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In this report we review recent progress in the understanding of the role of chirality in the multi-electron emission. A brief account of the chiral single-electron photoemission is given. In this case the chirality of the experimental set-up is brought about by an initial orientation of the target or/and by specifying a certain projection of the photoelectron spin. The dependence of the photoelectron spectrum on the chirality of the experiment is probed by changing the initial orientation of the target or by inverting the photoelectron spin projection. In a further section we envisage the direct transition of chiral electron pairs from an isotropic bound initial state into a double-continuum state following the absorption of a circularly polarised photon. We work out the necessary conditions under which the spectrum of the correlated photoelectron pair shows a chiral character, i.e. a dependence on the chirality of the exciting photon. The magnitude and the general behaviour of the chiral effects are estimated from simple analytical models and more elaborate numerical methods are presented for a more quantitative predictions. As a further example for the chiral multi-electron emission we study the photoelectron Auger-electron coincidence spectrum. The Auger hole is created by ionising a randomly oriented target by a circular polarised photon. We investigate how the helicity the photon is transferred to the emitted photoelectron pair. The theoretical findings are analysed and interpreted in light of recent experiments. In a final section we focus on the emission of correlated electrons where the initial state is already oriented, e.g. via optical pumping by circularly polarised light. The initial orientation of the atom is transferred to the continuum states following the ionisation of the target by low-energy electrons. We formulate and analyse the theoretical concepts for the transition of the screw sense of the initially bound atomic electron to the continuum electron pair. Numerical methods for the calculations of the cross-sections for the electron-impact ionisation of oriented atoms are presented and their results are contrasted against recent experimental data. 相似文献
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In this letter we calculate the inverse Cotton-Mouton effect (ICME) for the vacuum following the predictions of quantum electrodynamics. We compare the value of this effect for the vacuum with the one expected for atomic systems. We finally show that ICME could be measured for the first time for noble gases using state-of-the-art laser systems and for the quantum vacuum with near-future laser facilities like ELI and HiPER, providing in particular a test of the nonlinear behaviour of quantum vacuum at intensities below the Schwinger limit of 4.5×1033 W/m2.https://doi.org/10.1209/0295-5075/90/64003 相似文献
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A forward dispersion calculation is implemented for the spin polarizabilities γ1,,γ4 of the proton and the neutron. These polarizabilities are related to the spin structure of the nucleon at low energies and are structure-constants of the Compton scattering amplitude at
. In the absence of a direct experimental measurement of these quantities, a dispersion calculation serves the purpose of constraining the model building, and of comparing with recent calculations in heavy baryon chiral perturbation theory. 相似文献
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A.A. Vinokurov V.B. Il’in V.G. Farafonov 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(11):1733-4082
We present a Python package developed for computing optical properties of non-spherical particles. It gives a user friendly flexible framework that takes advantage of programming with the modern language supported by the abundant library of scientific packages. The framework is designed to include the methods and interfaces to third-party codes required to treat scatterers of different shape and structure. We describe the current state of our package called ScattPy, briefly outline its range of applicability and note its outstanding accuracy for inhomogeneous particles with a multilayered structure.We also demonstrate some advantages of the ScattPy in particular when performing large-scale computations. Such languages as Python are known to simplify the data input and allow one to include new classes and objects (e.g. those required to define new scatterer shapes) without recompiling the code. The main benefits come from their ability to organize easily the output data as a database. In the ScattPy we use the SQLite database and illustrate how it is utilized in our investigation of the phase function dependence on the shape, size and structure of spheroids. By comparing the time consumption of the ScattPy to that of an equivalent code written completely in FORTRAN we show that there can be no essential performance losses when using Python. 相似文献
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Ulrich K. Krieger Christian Braun 《Journal of Quantitative Spectroscopy & Radiative Transfer》2001,70(4-6):545-554
We use the deliquescence of single NaCl- and NaF-particles levitated in an electrodynamic trap to study light-scattering intensity fluctuations. During deliquescence the volume of the solid crystal and the liquid around it can be measured simultaneously with the light-scattering intensity. Such an experiment allows a comparison with numerical simulations of the intensity fluctuations in microdroplets containing inclusions. We find a power-law dependence proportional to the area of the inclusion for inclusions with radii approximately less than half in size of the total radius of the droplet. For larger inclusions this changes to a power law with a proportionality to the radius of the inclusion. A change of 30% in total radius does not change the intensity fluctuations. There seems to be no distinct difference in the behaviour of NaCl and NaF particles, even though the refractive index difference between solid inclusion and liquid host is 0.165 in the former and less than 0.009 in the latter. Furthermore, the fluctuation data of the pure NaCl deliquescence is applied to the ternary NaCl–CaCl2–H2O system and show good agreement with thermodynamic data. 相似文献
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The geometrical arrangement of slits in the secondary beam of light scattering photometers has been investigated. The hitherto
applied configuration of slits, vertically fixed on the secondary beam, requires a volume correction-sinϑ-for the determination
of the angle-dependent scattered intensity. Arrangements of slits with varying width which depends on the angle of observation
ϑ are proposed. They avoide the volume correction, or render the scattering volume independent of ϑ, and at the same time
increase the measuring accuracy.
For this purpose two types of mechanically guided slits are considered, utilizing parallelogram- and scissor-type mountings.
The conventional and new slit arrangements are used to determine the angular dependence of the total light flux intercepted
by the receiver, the angle subtended by the aperture, and the scattering volume, as well as the geometrical error. Measurements
employing a light scattering photometer with a fixed and a parallel-guided slit in the secondary beam are reported.
相似文献
16.
光散射在聚合物共混过程中形态发展研究的应用 总被引:2,自引:2,他引:0
本文应用光散射法和电子显微镜对聚丙烯/尼龙1010(PP/PA1010=90/10,体积比)共混体系的微观形态发展进行了研究。利用激光背散射在线系统采集了散射图象,由散射光斑的积分强度和Debye Bueche理论计算的相关距离讨论了共混物形态演化过程。结果表明,这一体系在共混初期(即1分钟以前)形态有较大变化,这一阶段是聚合物在密炼机中软化、变形和熔融混合的过程。由不同时刻采样并进行电镜观察发现,在共混1分钟以后,共混物的形态确实变化不大,这说明光散射法用于研究聚合物共混过程中的形态发展是可行的。 相似文献
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In biological suspensions, the forward light scattering is done mainly by the contribution of the suspended cells. The multiple scattering is almost always unavoidable, its contribution being described by Monte Carlo simulations or by approximate analytical formula. The Monte Carlo approach we propose moves one photon at a time and checks all scattering centers to find, at each simulation step, which one will scatter the photon. The validation of the simulation results is performed by comparing the obtained angular distribution with the predictions of the effective phase function theory reported recently in the literature and with the angle resolved experimental measurements performed on human red blood cells (RBCs) in suspensions at different hematocrits. The results show a good agreement in the small concentration range. 相似文献
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F. V. Díaz G. H. Kaufmann A. F. Armas G. E. Galizzi 《Optics and Lasers in Engineering》2001,35(6):325-333
This paper describes an optical method used for the determination of the plastic zone size generated on the surface of a notched metal specimen under conditions of low-cycle fatigue. The proposed optical method uses white-light scattering generated by plastically induced surface roughness on the specimen polished surface. By digital processing two images of the specimen surface, one recorded before and the other after the generation of the fatigue deformation, it is possible to evaluate the accumulated plastic damage. The plastic zone measured in the crack initiation stage is compared with the results obtained by a recrystallization technique. 相似文献
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Anatoli Borovoi Igor GrishinEdward Naats Ulrich Oppel 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,72(4):403-417
Backscattering of light by hexagonal ice columns and plates has been calculated by means of a ray-tracing code. It is shown that backscattering by the hexagonal ice cylinders at their arbitrary orientations is caused by a peculiar corner-reflector effect. A gigantic peak of backscattering is found at the angle of about 32.5° between the principal axis of a particle and the incidence direction for both hexagonal ice columns and plates. This peak is explained by multiple total internal reflections inside the crystals that take place for a part of incident rays. The obtained results on backscattering efficiency allow one to calculate backscattering by an ensemble of the hexagonal ice cylinders of various sizes, shapes and orientations. Slant lidar remote sensing of cirrus clouds for discrimination between aligned columns and plates is suggested as an application of the results obtained. 相似文献