Radiation, scattering electromagnetic

The optical properties of metal nanoparticles have traditionally relied on Mie tlieory, a purely classical electromagnetic scattering tlieory for particles witli known dielectrics [172]. For particles whose size is comparable to or larger tlian tire wavelengtli of the incident radiation, tliis calculation is ratlier cumbersome. However, if tire scatterers are smaller tlian -10% of tire wavelengtli, as in nearly all nanocrystals, tire lowest-order tenn of Mie tlieory is sufficient to describe tire absorjDtion and scattering of radiation. In tliis limit, tire absorjDtion is detennined solely by tire frequency-dependent dielectric function of tire metal particles and the dielectric of tire background matrix in which tliey are... 

When a beam of x-rays strikes an electron, some of the energy is momentarily absorbed, displacing the electron from its unperturbed position. This sets the electron in periodic motion with the same frequency as that of the exciting radiation. As a result the electron radiates an electromagnetic wave in all directions with the same frequency as the exciting radiation. This leads to the experimental observation that the incident radiation is scattered by the electron. A theoretical analysis (10, 11) of these events leads to the Thompson scattering equation which relates the intensity of x-rays scattered by a single electron, Ie, to that of the incident non-polarized x-radiation, I0 ... 

In radiation through the atmosphere, the electromagnetic energy is scattered and absorbed so that part of the radiation is observed to be distributed over the entire sky. The radiation within the sun solid angle is usually considered as direct radiation, but in addition, contains smaller amounts of scattered radiation. The scattering and absorption processes depend both spacially and spectrally upon the atmosphere composition and cloud distribution. It is useful to arbitrarily separate the input radiation to a surface into the direct and diffuse or scattered radiation. Figure 2 indicates the relative spectral magnitudes of each of these components. 

Spectroscopy is the measurement of electromagnetic radiation absorbed, scattered, or emitted by chemical species. Because different chemical species and electromagnetic radiation interact in characteristic ways, it is possible to tailor instrumentation to detect these interactions specifically and quantitatively. A simple absorption spectrophotometer, depicted schematically in Figure 12.2, contains components that are common to many spectroscopic devices and are representative of many of the basic principles of instrumentation found in analytical biochemistry. 

Kahnert FM Numerical methods in electromagnetic scattering theory, J Quant Spectrosc Radiat Transf79S0 775-S24, 2003. 

An alternative approach is to assume that the radiation from a finite array is associated entirely with the edge currents. While Maxwell s equations do not state specifically that radiation or scattering takes place from neither edges or element tips, it is nevertheless an observation that has proven valuable in classical electromagnetic theory. It is a convenient way to handle scattering properties from perfectly conducting half-planes, strips, wedges, and more, even when made of dielectric. 

Ayranci, I., Vaillon, R., and Selcuk, N. [2007] Performance of discrete dipole approximation for prediction of amplitude and phase of electromagnetic scattering by particles, J. Quant Spectrosc. Radiat. Transfer, 103,83-101. 

Peltoniemi, J. I. (1996) Variational volume integral equation method for electromagnetic scattering by irregular grains,/. Quant. Spectrosc. Radiat. Transfer, 55, 627-6A7. 

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