Silver nanostructures are containers for surface plasmons - the collective oscillation of conduction electrons in phase with incident light. By controlling the shape of the container, one can control the ways in which electrons oscillate, and in turn how the nanostructure scatters light, absorbs light, and enhances local electric fields. With a series of discrete dipole approximation (DDA) calc...

We present the computation of effective refractive coefficients for inhomogeneous two-component grains with 3 kinds of inclusions with m incl = 3.0 + 4.0i, 2.0 + 1.0i, 2.5 + 0.0001i and a matrix with m m = 1.33 + 0.01i for 11 volume fractions of inclusions from 0% to 50%. The coefficients of extinction for these grains have been computed using a discrete dipole approximation (DDA). Computation ...

We present a discrete dipole approximation ~DDA! method to determine extinction and Raman intensities for small metal particles of arbitrary shape. The Raman intensity calculation involves evaluation of surface electromagnetic fields, and thus is relevant to surface enhanced Raman scattering ~SERS! intensities. We demonstrate convergence of the method by considering light absorption and scatter...

[1] The applicability of the Rayleigh-Gans approximation (RGA) for scattering by snowflakes is studied in the microwave region of the electromagnetic spectrum. Both the shapes of the single ice crystals, or monomers, and their amounts in the modeled snowflakes are varied. For reference, the discrete-dipole approximation (DDA) is used to produce numerically accurate solutions to the single-scatt...

Ice sphere backscatter has been calculated using both Mie theory and the discrete dipole approximation (DDA) at a wavelength of 3.2 mm (94 GHz). The electric dipole, magnetic dipole and electric quadrupole contributions to spherical particle backscatter have been analyzed. The results show that there is a resonance area around particle size parameter of 1.5, where the calculated backscatter err...

.......................................................................................................................................................... 4 Acknowledgements .......................................................................................................................................... 5 Chapter 1 Introduction...............................................................

We develop a numerical technique for simulating metamaterial electromagnetic response based on an adaptation of the discrete dipole approximation (DDA). Our approach reduces each constituent metamaterial element within the composite to a point dipole with electric and magnetic polarizabilities, rather than assuming a homogenized effective material. We first validate the approach by computing th...

Elastic light scattering by mature red blood cells (RBCs) was theoretically and experimentally analyzed by use of the discrete dipole approximation (DDA) and scanning flow cytometry (SFC), respectively. SFC permits measurement of the angular dependence of the light-scattering intensity (indicatrix) of single particles. A mature RBC is modeled as a biconcave disk in DDA simulations of light scat...

Cirrus clouds play an important role in the Earth’s radiation budget. The transfer of radiation through ice cloud layers depends on the particle phase, concentration, size distribution, and the cloud thickness and shape. Consequently, for reliable simulations of present and future climate using General Circulation Models an accurate representation of ice cloud properties is essential. This give...