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Multiple Scattering Probes of Disordered Materials
Published online by Cambridge University Press: 29 November 2013
Extract
A large class of materials of great technological importance and scientific interest are highly disordered on length scales comparable to, or larger than, the wavelength of light. As a consequence of this disorder, these materials are often composed of a large number of regions with different indices of refraction, separated by interfaces that are abrupt on the scale of the wavelength of light. Each of these interfaces refracts or scatters light, making these materials quite opaque optically. Even in the absence of absorption, the strong scattering precludes the direct transmission of light rays through the material. This greatly complicates the study of these materials.
Examples of these disordered materials abound. Many are complex fluids; colloidal suspensions and other dispersions such as foams and emulsions often consist of particles or droplets whose diameters are comparable to the wavelength of light. Unless they are very dilute, these dispersions are typically highly opaque. Other materials consist of solid grains of similar sizes without the surrounding fluid. For example, most ceramics are composed of oxide grains sintered together; the voids between the grains lead to the large number of interfaces, and hence to the strong scattering and opaque appearance commonly associated with these materials. Similarly, many porous materials also possess a high density of voids that scatter light; filters, oxide catalyst supports, and even rocks are all optically opaque because of the strong scattering. Sand and other unconsolidated granular materials are also opaque in part because of the large number of interfaces that scatter light.
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- Mesoscopic Disorder
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- Copyright © Materials Research Society 1994
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