Light scattering

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

A suite of programs for calculating x‐ray absorption, reflection, and diffraction performance for a variety of materials at arbitrary wavelengths

Abstract: One of the most useful characteristics of synchrotron radiation is the wide spectral distribution of the source. For applications involving tuned monochromatic beams it is often helpful to predict the x‐ray optical characteristics of a sample or the beam line optics at a particular wavelength. In contrast to this desire stands the fact that tabulated values for the optical parameters of interest are generally available only at wavelengths corresponding to typical x‐ray tube sources. We have developed a suite of fortran programs which calculate photoabsorption cross sections and atomic scattering factors for materials of arbitrary, uniform composition or for arbitrary layered materials. Further, the suite includes programs for calculation of x‐ray diffraction or reflection from such materials. These programs are of use for experimental planning, data analysis, and predictions of performance of beam line optical elements.

Evidence of intrinsic differences in the light scattering properties of tumorigenic and nontumorigenic cells

Abstract: BACKGROUND. The objective of this study was to determine whether there are intrinsic differences in the light scattering properties of tumorigenic and nontumorigenic cells from a multistep carcinogenesis model. METHODS. Wavelength-dependent and polarization-dependent light scattering properties of cell suspensions were measured. RESULTS. Statistically significant differences were found between the tumorigenic and nontumorigenic cells. CONCLUSIONS. Differences in the light scattering properties of tumorigenic and nontumorigenic cells are attributed to a change in the average size of the scattering centers on the order of a few ten of nanometers. This work is relevant to the development of noninvasive optical methods for cancer diagnosis.

Electric and magnetic dipolar response of germanium nanospheres: interference effects, scattering anisotropy, and optical forces

Abstract: Thecoherentcombinationofelectricandmagneticresponsesisthebasisoftheelectro- magnetic behavior of new engineered metamaterials. The basic constituents of their meta-atoms usually have metallic character and consequently high absorption losses. Based on standard "Mie" scattering theory, we found that there is a wide window in the near-infrared (wavelengths 1t o 3μm), where light scattering by lossless submicrometer Ge spherical particles is fully described by their induced electric and magnetic dipoles. The interference between electric and magneticdipolarfieldsisshowntoleadtoanisotropicangulardistributionsofscatteredintensity, including zero backward and almost zero forward scattered intensities at specific wavelengths, which until recently was theoretically established only for hypothetically postulated magnetodi- electric spheres. Although the scattering cross section at zero backward or forward scattering is exactly the same, radiation pressure forces are a factor of 3 higher in the zero forward condition.

Three-dimensional analysis of scattering losses due to sidewall roughness in microphotonic waveguides

Abstract: We present a three-dimensional (3-D) analysis of scattering losses due to sidewall roughness in rectangular dielectric waveguides valid for any refractive-index contrast and field polarization. The analysis is based on the volume current method and uses array factors to introduce significant mathematical simplifications to better understand the influence of individual waveguide parameters on scattering losses. We show that the typical two-dimensional (2-D) analyses can substantially overestimate scattering losses in small waveguides and that scattering losses exhibit considerable polarization dependence. We produce scattering-loss estimates for a wide variety of waveguides and provide guidelines for design of waveguide cross sections that are less sensitive to sidewall roughness.

Colloidal properties of synthetic hectorite clay dispersions

Abstract: The structure and interactions in aqueous dispersions of a synthetic hectorite-type clay, Laponite RD, have been investigated at low ionic strength ([Na] ∼ 10−3 mole dm−3) by static (SLS) and dynamic light scattering (DLS) and small angle neutron scattering (SANS). At low concentrations (≲0.01 g ml−1) both SLS and DLS show that the dispersions contain discrete particles, which do not interact strongly. The molecular weight and hydrodynamic properties of these particles are similar to those of circular disks of diameter ∼30 nm and thickness ∼ 1 nm. At higher concentrations (≳0.03 g ml−1), where gelation and the development of elasticity occurs, there are clear indications of interparticle interactions from changes in the light scattering and SANS behavior. These interactions are ascribed to an overlap of the electrical double layers surrounding the clay particles. It is proposed that the resultant interparticle repulsion gives rise to an equilibrium structure, having elastic properties, in which the translational mobility of the particles is restricted. From the scattering behavior there is no evidence of an association of the particles in an edge-to-face type structure which is now accepted to occur extensively at much higher ionic strengths in other clay dispersions, such as kaolinites and bentonites. The proposed gelation mechanism of Laponite dispersions at low ionic strength is, however, likely to be similar to that which has been suggested previously from rheological studies to occur with montmorillonite, which is a clay which can also undergo osmotic swelling.