dispersion

dispersion in chemistry, mixture in which fine particles of one substance are scattered throughout another substance. A dispersion is classed as a suspension , colloid , or solution . Generally, the particles in a solution are of molecular or ionic size; those in a colloid are larger but too small to be observed with an ordinary microscope; those in a suspension can be observed under a microscope or with the naked eye. A coarse mixture (e.g., sand mixed with sugar) is usually not thought of as a dispersion.

dispersion The English translation of diaspora.

dispersion
1. The splitting of light into its constituent colours by a prism or diffraction grating. High dispersion means that the spectrum of an object is spread out more than in low dispersion, and thus more details can be seen; the degree of dispersion thus governs spectral resolution. A high-resolution spectrograph will produce a typical dispersion of 1–2 nm/mm.

2. A phenomenon in which electromagnetic waves of different frequencies travel at different speeds in certain media, such as ionized gases (plasmas). Interstellar matter is largely ionized hydrogen and is therefore dispersive. The time delay of a wave introduced by dispersion depends on the electron density along the line of sight, and is inversely proportional to the square of the observing frequency. Dispersion smears out rapid fluctuations in the source, a matter of great importance in the observation of pulsars. See also Dedispersion.