scispace - formally typeset
Search or ask a question
Topic

Light scattering

About: Light scattering is a research topic. Over the lifetime, 37721 publications have been published within this topic receiving 861581 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, the basic kinetic equation which describes the Brownian motion is set up and applied to two particular experiments, the Kerr effect and dynamic light scattering, and the principal results are : (1) the characteristic relaxation time τr of the Kerr Effect is very long, and depends strongly on the concentration ρ and the molecular weight M such that τr∝ρ2M7, and relaxation is nonexponential.
Abstract: A concentrated solution of rod-like macromolecules is thermodynamically ideal if the rods are thin enough, but its dynamical behaviour is completely different from that of a dilute solution because of the “entanglement” constraint that the rods cannot pass through each other. This characteristic feature is discussed. First the basic kinetic equation which describes the Brownian motion is set up. This equation is then applied to two particular experiments, the Kerr effect and dynamic light scattering. The principal results are : (1) The characteristic relaxation time τr of the Kerr effect is very long, and depends strongly on the concentration ρ and the molecular weight M such that τr∝ρ2M7, and the relaxation is non-exponential. (2) The dynamical structure factor S(k, t) measured by light scattering has a characteristic shape which is independent of concentration; the initial slope of S(k, t) being about half the value predicted for dilute solution; S(k, t) has a very long tail as S(k, t)∝ 1/√t.

432 citations

Journal ArticleDOI
TL;DR: In this paper, a dipole-limit calculation based on confocal ellipsoids was used to simulate the spectra of the core/shell nanorods using bulk dielectric functions.
Abstract: Au/Ag core/shell nanorods with different shell thickness were synthesized in aqueous solution by chemically depositing silver on gold nanorods surface. With the silver coating, the longitudinal plasmon mode of the nanorods shifted blue and was enhanced. A dipole-limit calculation, based on confocal ellipsoids, simulates the spectra of the core/shell nanorods using bulk dielectric functions. Good agreement with the experimental result was achieved. Light scattering spectra of single nanorods were taken by dark-field microscopy to measure the homogeneous line width. The scattering spectra of single gold nanorods are less than 10% broader than the theoretical value, while the spectra of silver-coated nanorods are systematically 40−50% broader. The additional damping of the plasmon was modeled as the extra scattering at the Au−Ag interface and the nanorods surface. A model for evaluating the plasmon damping in inhomogeneous metallic systems with interfaces is presented.

428 citations

Journal ArticleDOI
TL;DR: In this article, the expansion coefficients of the T-matrix were derived for axially symmetric light scattering by ensembles of independently scattering spheroids and Chebyshev particles.
Abstract: Light scattering by ensembles of independently scattering, randomly oriented, axially symmetric particles is considered. The elements of the scattering matrices are expanded in (combinations of) generalized spherical functions; this is advantageous in computations of both single and multiple light scattering. Waterman’s T-matrix approach is used to develop a rigorous analytical method to compute the corresponding expansion coefficients. The main advantage of this method is that the expansion coefficients are expressed directly in some basic quantities that depend on only the shape, morphology, and composition of the scattering axially symmetric particle; these quantities are the elements of the T matrix calculated with respect to the coordinate system with the z axis along the axis of particle symmetry. Thus the expansion coefficients are calculated without computing beforehand the elements of the scattering matrix for a large set of particle orientations and scattering angles, which minimizes the numerical calculations. Like the T-matrix approach itself, the method can be used in computations for homogeneous and composite isotropic particles of sizes not too large compared with a wavelength. Computational aspects of the method are discussed in detail, and some illustrative numerical results are reported for randomly oriented homogeneous dielectric spheroids and Chebyshev particles. Results of timing tests are presented; it is found that the method described is much faster than the commonly used method of numerical angle integrations.

428 citations

Journal ArticleDOI
TL;DR: These studies provide a basis for the understanding of photon diffusion in strongly scattering media in the presence of absorbing and reflecting objects and allow for a determination of the conditions for obtaining maximum resolution and penetration for applications to optical tomography.
Abstract: Light propagation in strongly scattering media can be described by the diffusion approximation to the Boltzmann transport equation. We have derived analytical expressions based on the diffusion approximation that describe the photon density in a uniform, infinite, strongly scattering medium that contains a sinusoidally intensity-modulated point source of light. These expressions predict that the photon density will propagate outward from the light source as a spherical wave of constant phase velocity with an amplitude that attenuates with distance r from the source as exp(-alpha r)/r. The properties of the photon-density wave are given in terms of the spectral properties of the scattering medium. We have used the Green's function obtained from the diffusion approximation to the Boltzmann transport equation with a sinusoidally modulated point source to derive analytic expressions describing the diffraction and the reflection of photon-density waves from an absorbing and/or reflecting semi-infinite plane bounded by a straight edge immersed in a strongly scattering medium. The analytic expressions given are in agreement with the results of frequency-domain experiments performed in skim-milk media and with Monte Carlo simulations. These studies provide a basis for the understanding of photon diffusion in strongly scattering media in the presence of absorbing and reflecting objects and allow for a determination of the conditions for obtaining maximum resolution and penetration for applications to optical tomography.

428 citations

Journal ArticleDOI
TL;DR: Fan et al. as mentioned in this paper reviewed the fundamental aspects of light scattering by small spherical particles, emphasizing the phenomenological treatments and new developments in this field, and described how Mie theory can be used to describe optical scattering of small dielectric particles, and, in the case of metallic particles, how light excites surface plasmons to generate an optical response featuring asymmetric Fano resonances.
Abstract: Light scattering by small particles has a long and interesting history in physics. Nonetheless, it continues to surprise with new insights and applications. This includes new discoveries, such as novel plasmonic effects, as well as exciting theoretical and experimental developments such as optical trapping, anomalous light scattering, optical tweezers, nanospasers, and novel aspects and realizations of Fano resonances. These have led to important new applications, including several ones in the biomedical area and in sensing techniques at the single-molecule level. There are additionally many potential future applications in optical devices and solar energy technologies. Here we review the fundamental aspects of light scattering by small spherical particles, emphasizing the phenomenological treatments and new developments in this field. The interaction of light with small spherical particles has long been a topic of interest to researchers. Indeed, understanding many natural phenomena, including rainbows and the solar corona, requires knowledge of how light behaves in such circumstances. Xiaofeng Fan and co-workers from Jilin University in China and Oak Ridge National Laboratory in the USA have now reviewed the physics and applications that arise during the interaction of light with small spherical particles. The researchers describe how Mie theory can be used to describe optical scattering by small dielectric particles, and, in the case of metallic particles, how light excites surface plasmons to generate an optical response featuring asymmetric Fano resonances. In the special case when metallic particles are surrounded by an optical gain medium, plasmons can be amplified; the resulting device is known as a ‘spaser’.

428 citations


Network Information
Related Topics (5)
Dielectric
169.7K papers, 2.7M citations
87% related
Scattering
152.3K papers, 3M citations
86% related
Raman spectroscopy
122.6K papers, 2.8M citations
86% related
Laser
353.1K papers, 4.3M citations
85% related
Polymer
131.4K papers, 2.6M citations
85% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023235
2022537
2021485
2020680
2019751
2018799