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Scattering cross section, customarily denoted by Cb [length2], is defined for a particle by the following equation (for example, Bohren and Huffman 1983):
| Cb = Φbp / E | (1) |
where Φbp [power] is the power scattered by the particle, and E [power length-2] is the irradiance of an electromagnetic radiation (ER) beam illuminating the particle.
The scattering cross section is related to the scattering coefficient of a dispersion (of identical particles) by the following equation (see Absorption cross section for a parallel derivation):
| Cb = b / n | (2) |
where b [length-1] is the scattering coefficient of a dispersion and n [length-3] is the number concentration of particles in the dispersion. This equation provides an operational method of experimental determination of the scattering cross section for a dispersion of particles. For single-particle measurements, as in flow-cytometry, the scattering cross section of a particle can be estimated by comparing the intensity of light it scatters to that scattered by a similar "calibration" particle (for example, Chung et al 1998).
Two other scattering-related cross sections are also in use: the forward scattering cross section, Cbf , that specifies the cross section of a particle for light scattering into scattering angles ranging from 0° to 90°, and backscattering cross section, Cbb, that specifies the cross section of a particle for light scattering into angles from 90° to 180°.
| CITATION: Jonasz M. 2006. Scattering cross sections (www.tpdsci.com/Tpc/ScaCs.php). In: Top. Part. Disp. Sci. (www.tpdsci.com). |
HISTORY: Published: 17-Jan-2006 Modified: 07-Sep-2006 Peer-reviewed: 19-Feb-2007 |
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