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Scattering may also refer to particle-particle collisions between molecules, atoms, electrons, photons and other particles. Examples are: cosmic rays scattering by the Earth's upper atmosphere; particle collisions inside particle accelerators; electron scattering by gas atoms in fluorescent lamps; and neutron scattering inside nuclear reactors.

The types of non-uniformities which can cause scattering, sometimes known as scatterers or scattering centers, are too numerous to list, but a small sample includes fibers in clothing. The effects of such features on the path of almost any type of propagating wave or moving particle can be described in the framework of scattering theory.



  • Single and multiple scattering 1
  • Scattering theory 2
  • Electromagnetic scattering 3
  • See also 4
  • References 5
  • External links 6

Single and multiple scattering

Zodiacal light is a glow originated in the scattering of sunlight by dust located between the planets that are spread through the plane of the Solar System.[1]


With multiple scattering, the randomness of the interaction tends to be averaged out by the large number of scattering events, so that the final path of the radiation appears to be a deterministic distribution of intensity. This is exemplified by a light beam passing through thick fog. Multiple scattering is highly analogous to diffusion, and the terms multiple scattering and diffusion are interchangeable in many contexts. Optical elements designed to produce multiple scattering are thus known as diffusers. Coherent backscattering, an enhancement of backscattering that occurs when coherent radiation is multiply scattered by a random medium, is usually attributed to weak localization.

Not all single scattering is random, however. A well-controlled laser beam can be exactly positioned to scatter off a microscopic particle with a deterministic outcome, for instance. Such situations are encountered in radar scattering as well, where the targets tend to be macroscopic objects such as people or aircraft.

Similarly, multiple scattering can sometimes have somewhat random outcomes, particularly with coherent radiation. The random fluctuations in the multiply scattered intensity of coherent radiation are called speckles. Speckle also occurs if multiple parts of a coherent wave scatter from different centers. In certain rare circumstances, multiple scattering may only involve a small number of interactions such that the randomness is not completely averaged out. These systems are considered to be some of the most difficult to model accurately.

The description of scattering and the distinction between single and multiple scattering are often highly involved with wave–particle duality.

Scattering theory

Scattering theory is a framework for studying and understanding the scattering of waves and particles. Prosaically, wave scattering corresponds to the collision and scattering of a wave with some material object, for instance sunlight scattered by rain drops to form a rainbow. Scattering also includes the interaction of billiard balls on a table, the Rutherford scattering (or angle change) of alpha particles by gold nuclei, the Bragg scattering (or diffraction) of electrons and X-rays by a cluster of atoms, and the inelastic scattering of a fission fragment as it traverses a thin foil. More precisely, scattering consists of the study of how solutions of partial differential equations, propagating freely "in the distant past", come together and interact with one another or with a boundary condition, and then propagate away "to the distant future".

Electromagnetic scattering


Electromagnetic waves are one of the best known and most commonly encountered forms of radiation that undergo scattering. Scattering of light and radio waves (especially in radar) is particularly important. Several different aspects of electromagnetic scattering are distinct enough to have conventional names. Major forms of elastic light scattering (involving negligible energy transfer) are Rayleigh scattering and Mie scattering. Inelastic scattering includes Brillouin scattering, Raman scattering, inelastic X-ray scattering and Compton scattering.

Light scattering is one of the two major physical processes that contribute to the visible appearance of most objects, the other being absorption. Surfaces described as white owe their appearance to multiple scattering of light by internal or surface inhomogeneities in the object, for example by the boundaries of transparent microscopic crystals that make up a stone or by the microscopic fibers in a sheet of paper. More generally, the gloss (or lustre or sheen) of the surface is determined by scattering. Highly scattering surfaces are described as being dull or having a matte finish, while the absence of surface scattering leads to a glossy appearance, as with polished metal or stone.

Spectral absorption, the selective absorption of certain colors, determines the color of most objects with some modification by elastic scattering. The apparent blue color of veins in skin is a common example where both spectral absorption and scattering play important and complex roles in the coloration. Light scattering can also create color without absorption, often shades of blue, as with the sky (Rayleigh scattering), the human blue iris, and the feathers of some birds (Prum et al. 1998). However, resonant light scattering in nanoparticles can produce many different highly saturated and vibrant hues, especially when surface plasmon resonance is involved (Roqué et al. 2006).

Models of light scattering can be divided into three domains based on a dimensionless size parameter, α which is defined as:

\alpha = \pi D_\text{p} / \lambda,

where πDp is the circumference of a particle and λ is the wavelength of incident radiation. Based on the value of α, these domains are:

α ≪ 1: Rayleigh scattering (small particle compared to wavelength of light);
α ≈ 1: Mie scattering (particle about the same size as wavelength of light, valid only for spheres);
α ≫ 1: geometric scattering (particle much larger than wavelength of light).






See also


  • Bohren, Craig F.; Donald R. Huffman (1983). Absorption and Scattering of Light by Small Particles.  
  • Colton, David; Rainer Kress (1998). Inverse Acoustic and Electromagnetic Scattering Theory.  
  • Gonis, Antonios; William H. Butler (1999). Multiple Scattering in Solids.  
  • Prum, Richard O.; Rodolfo H. Torres; Scott Williamson; Jan Dyck (1998). "Coherent light scattering by blue feather barbs".  
  • Roqué, Josep; J. Molera; P. Sciau; E. Pantos; M. Vendrell-Saz (2006). "Copper and silver nanocrystals in lustre lead glazes: development and optical properties".  
  • Seinfeld, John H.; Pandis, Spyros N. (2006). Atmospheric Chemistry and Physics - From Air Pollution to Climate Change (2nd Ed.). John Wiley and Sons, Inc. ISBN 0-471-82857-2
  1. ^ "Zodiacal Glow Lightens Paranal Sky". ESO Picture of the Week. Retrieved 2 December 2013. 

External links

  • Research group on light scattering and diffusion in complex systems
  • Multiple light scattering from a photonic science point of view
  • Neutron Scattering Web
  • World directory of neutron scattering instruments
