Extinction scattering

Measurement over medium view path (10-25 km) measures total extinction, scattering and absorption unaffected by clouds, night... 

EXTINCTION, SCATTERING, AND ABSORPTION 3.4 EXTINCTION, SCATTERING, AND ABSORPTION... 

We may define efficiencies (or efficiency factors) for extinction, scattering, and absorption ... 

We derived Cext by two different methods. The first, integrating the Poynt-ing vector over an imaginary sphere around the particle, emphasized the conservation of energy aspect of extinction extinction = scattering + absorption. The second, focusing attention on what is measured in a hypothetical... 

The extinction, scattering, and radar backscattering efficiencies are (to terms of order x4)... 

Several authors have addressed the determination of the optical properties of aqueous titanium dioxide suspensions in the context of photoreactor modeling (Brandi et al., 1999 Cabrera et al., 1996 Cured et al., 2002 Salaices et al., 2001, 2002 Satuf et al., 2005 Yokota et al., 1999). Among the determined properties are extinction, scattering, and absorption coefficients, as well as the asymmetry parameter of the scattering phase function. In general the procedures involve fitting of a radiative transfer model to the experimental results for reflectance and transmittance of radiation. 

The effective attenuation coefficient is therefore proportional to the total (extinction) scattering cross section, or equivalently, to the fraction of the energy flux density scattered in all directions (opp + Ops) per unit distance travelled, plus the fraction converted into heat by the inclusions (oa). ... 

In 1908, Mie presented a solution to Maxwell s equations that describes the extinction spectra (extinction = scattering + absorption) of spherical particles of arbitrary size. Mie s solution remains of great interest to this day, although there are no analytical solutions for metal nanoparticles of interesting shapes such as nanorods, nanocubes and nanoprisms. Numerical approaches such as the discrete dipole rqiproximation (DDA) have been employed to investigate the effect of nanoparticle size and shape on the extinction spectra, and the calculation of the intensity and spatial distribution of the local electromagnetic field [1-5,31]. 

Q Efficiency factors for particle absorption, extinction, scattering (m2), Eq. 7.180 q Radiative flux (W/m2)... 

FIGURE 24.10 Total extinction, scattering, and absorption coefficients for internal versus external mixtures of soot and (NH4)2S04. 

Essentially, Cgcat and Cabs represent the electromagnetic powers removed from the incident wave as a result of scattering and absorption of the incident radiation, while Cext gives the total electromagnetic power removed from the incident wave by the combined effect of scattering and absorption. The optical cross-sections have the dimension of area and depend on the direction and polarization state of the incident wave as well on the size, optical properties and orientation of the particle. The efficiencies (or efficiency factors) for extinction, scattering and absorption are defined as... 

It is interesting to compare these results with calculations of the triangle anteima in ftee space. Plots of the extinction, scattering, and absorption cross sections for the 100-nm triangle antenna in free space along with the peak field intensity at the apex are shown in Fig. 32. The resonance occurs at 675 nm, significantly shifted from the resonance wavelength in the presence of the medium. The peak field intensity occurs at the apex of the antenna, and is clearly... 

Figure 32. Extinction, scattering, and absorption cross sections normalized by the area of the antenna for the 100-nm triangle antenna on a glass substrate as a function of wavelength. The peak E field intensity versus wavelength is also plotted.

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