共查询到20条相似文献,搜索用时 15 毫秒
1.
S.A. El-Wakil 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,102(2):152-161
The time-dependent radiation transfer equation in a finite plane geometry with Rayleigh scattering is studied. The traveling wave transformation is used to obtain the corresponding stationary-like equation. Pomraning-Eddington approximation is then used to find the solution. Numerical results for reflectivity at the left boundary and transmissivity from the right boundary are presented at different times. The medium is assumed to have specular-reflecting boundaries with angular-dependent externally incident flux. Two different weight functions are introduced to force the boundary conditions to fulfill. 相似文献
2.
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
3.
Summary We have performed Brillouin and depolarized Rayleigh light scattering on water-methanol solutions as a function of methanol
molar fraction and temperature. For this system, molecular-dynamics (MD) simulation predicts that a shell of water forms around
a methanol molecule, prediction which has been recently confirmed by neutron diffraction experiments. The results obtained
by light scattering and presented here confirm previous observations and show, in addition, an increase of the stability in
time of the water structure in the shells when temperature decreases and methanol concentration approaches a particular value.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
4.
给出了不同坐标系中介质参数张量的变换,得到了磁化冷等离子体球电场的表达式,得出了任意各向异性目标散射场的表达式,研究了磁化冷等离子体球的微分散射截面、散射截面等的函数关系,仿真结果与有关文献一致,表明了本算法的有效性,从而为各向异性目标识别等提供理论支持。 相似文献
5.
Characterization of premixed swirling methane/air diffusion flame through filtered Rayleigh scattering 下载免费PDF全文
Characteristics of a premixed, swirl methane/air diffusion flame at atmospheric pressure are measured by filtered Rayleigh scattering (FRS). Three operating conditions are investigated with the equivalence ratios of the methane/air flame covering a range of 0.67—0.83. Under each condition, single-shot and averaged FRS images over a region measured 39.3×65.6 mm2 at seven cross sections of the flame are collected to demonstrate the flame behavior. A gradient calculation algorithm is applied to identify reaction zone locations and structures in the instantaneous FRS measurements. Statistical analysis for the mean FRS measurements is performed by means of joint probability density functions. The experimental results indicate that thermochemical state of the swirl flame is strongly influenced by equivalence ratio, leading to varieties of flame structures and temperature distributions. The gradient of the instantaneous FRS images clearly illustrates the characteristics of the reaction zone. The results also demonstrate that FRS can provide detailed insights into the behavior of turbulent flames. 相似文献
6.
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
7.
给出了不同坐标系中介质参数张量的变换,得到了磁化冷等离子体球电场的表达式,得出了任意各向异性目标散射场的表达式,研究了磁化冷等离子体球的微分散射截面、散射截面等的函数关系,仿真结果与有关文献一致,表明了本算法的有效性,从而为各向异性目标识别等提供理论支持。 相似文献
8.
Anna V. Svanidze Sergey G. Lushnikov Vadim P. Romanov Seiji Kojima 《Journal of Raman spectroscopy : JRS》2012,43(10):1510-1514
We present results of Brillouin light scattering studies of lysozyme and guanidine hydrochloride solutions in the temperature range 290–350 K. The Brillouin spectra of 6 M guanidine hydrochloride have been found to contain an additional component in Rayleigh scattering that manifests itself as a broad quasi‐elastic scattering line centered at the unshifted frequency and described by a Lorentz function (i.e. a Debye relaxor with relaxation time τ1 ~ 25 ps at room temperature). The temperature dependence of τ1 is described by the Arrhenius law with activation energy Ea = 0.11 ± 0.01 eV and prefactor τ0= 0.33 ± 0.03 ps. The Brillouin spectra of lysozyme denatured by 6 M guanidine hydrochloride exhibit a more complicated structure of the additional contribution into Rayleigh scattering, which is fitted best of all by a sum of two Lorentzians centered at the unshifted frequency (with relaxation times τ1 ~ 19 ps and τ2 ~ 180 ps at 339 K). Possible origins of the quasi‐elastic scattering are discussed. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
9.
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
10.
Summary We have performed extensive studies of a three-component microemulsion system composed of AOT-water-decane (AOT=sodium-bis-ethylhexyl-sulfosuccinate
is an ionic surfactant) using small-angle light scattering (SALS). The small-angle scattering intensities are measured in
the angular interval 0.001–0.1 radians, corresponding to a Bragg wave number range of 0.14 μm−1<Q<<1.4 μm−1. The measurements were made by changing temperature and volume fraction ϕ of the dispersed phase (water + AOT) in the range
0.05<ϕ<0.75. All samples have a fixed water-to-AOT molar ratio,w=[water]/[AOT]=40.8, in order to keep the same average droplet size in the stable one-phase region. With the SALS technique,
we have been able to observe all the phase boundaries of a very complex phase diagram with a percolation line and many structural
organizations within it. We observe at the percolation transition threshold, a scaling behavior of the intensity data. This
behavior is a consequence of a clustering among microemulsion droplets near the percolation threshold. In addition, we describe
in detail a structural transition from a droplet microemulsion to a bicontinuous one as suggested by a recent small-angle
neutron scattering experiment. The loci of this transition are located several degrees above the percolation temperatures
and are coincident with the maxima previously observed in shear viscosity. From the data analysis, we show that both the percolation
phenomenon and this novel structural transition are derived from a large-scale aggregation between microemulsion droplets. 相似文献
11.
12.
T. Freixanet B. Sermage J. Bloch J. Y. Marzin B. Gayral R. Planel 《Physica E: Low-dimensional Systems and Nanostructures》2000,7(3-4)
We study the angular dependence of the emission from cavity polaritons resonantly excited by a picosecond laser pulse. We observe that, in the first stage, the initial excitation is rapidly redistributed by elastic scattering along a well-defined ring in the wave vector space resulting in an angular-dependent emission. This initial transfer, which conserves the polarization, is attributed mainly to resonant Rayleigh scattering of polaritons. We also study the width of this ring and show that it is detuning dependent, reflecting the energy dispersion of the polaritons. At longer delay, the emission is found to be isotropic and depolarized, in agreement with previous studies. 相似文献
13.
Summary We have performed extensive small-angle light scattering (SALS) measurements on a three-component microemulsion (AOT/decane/water)
as a function of the dispersed phase concentration and the temperature. All samples have a water/AOT molar fractionw=40.8. Such a system presents a very complex phase diagram with many structural configurations. With the SALS technique, we
have been able to observe all the phase separation lines. In particular we give details on the system structure on the percolation
phenomenon and on the bicontinuous phase recently observed. In particular we show that the percolation is driven by a long-scale
aggregation between microemulsion droplets.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
14.
海水水下温度的快速大范围测量是海洋监测的重要内容,在民用和军事领域都有着至关重要的意义,本文提出了采用相干瑞利散射方法测量海水水下温度的新方法:用宽带高速光电探测器接收本振激光和海水后向瑞利散射光相干产生的差频信号,进行傅里叶变换分析获取海水瑞利散射展宽谱,从而反演海水温度,首先从海水的热力学特性出发,对利用瑞利散射谱测量海水水下温度的基本原理进行了理论研究和软件模拟;然后对采用相干探测测量海水瑞利散射谱的测量方法进行了理论分析和软件模拟;在此基础上对瑞利散射海水水下温度测量精度进行了分析,得出当水体瑞利散射频谱半宽度测量精度为1 MHz时,测温精度约为0.35 K。 相似文献
15.
16.
17.
Laser interferometer gravitational wave detectors require very high optical quality test masses. We report the bulk Rayleigh scattering in high quality fused silica samples. Results show that the scattering of the high quality fused silica is similar for various grades of fused silica from Heraeus. The total integrated scattering is about 0.7 ppm cm− 1at 1064 nm wavelength, which agrees with the theoretical value calculated using known fused silica parameters. All samples show Rayleigh scattering ratio inhomogeneity of ~ 4%. 相似文献
18.
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.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 65–72, January–February, 2006. 相似文献
19.
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
20.
大气压空气电火花激波等离子体射流的电子密度在亚微秒时间尺度上瞬变,其电子密度的测定很难.基于微波瑞利散射原理,本文测量了空气电火花冲击波流注放电等离子体射流的时变电子密度.实验结果表明:测量系统的标定参数A为1.04 × 105 V·Ω·m–2;空气流注放电等离子体射流的电子密度与等离子体射流的半径和长度有关,结合高速放电影像展示的等离子体射流的等效半径和等效长度,测定的电子密度在1020 m–3的量级,且随时间先快速增长至峰值再成指数衰减.此外,本文还探讨了等离子体射流的不同等效尺度对测定结果的影响;分析结果表明,采用时变等效半径和时变等效长度的计算结果最有效,且第1个快速波峰是由光电离的电离波导致的. 相似文献