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A colloidal crystal is an ordered array of colloidal particles and fine grained materials analogous to a standard crystal whose repeating subunits are atoms or molecules. [1] A natural example of this phenomenon can be found in the gem opal, where spheres of silica assume a close-packed locally periodic structure under moderate compression.
Quantum dots have been gaining interest from the scientific community because of their interesting optical properties, the main being band gap tunability. When an electron is excited to the conduction band, it leaves behind a vacancy in the valence band called hole. These two opposite charges are bound by Coulombic interactions in what is ...
Perovskite MAPbX 3 thin films have been shown to be promising materials for optical gain applications such as lasers and optical amplifiers. [137] [138] Afterwards, the lasing properties of colloidal perovskite NCs such as CsPbX 3 nanocubes, [19] [139] MAPbBr 3 nanoplatelets [113] and FAPbX 3 nanocubes [83] [82] were also demonstrated.
Photonic crystal fibres were first developed by Philip Russell in 1998, and can be designed to possess enhanced properties over (normal) optical fibres. Study has proceeded more slowly in three-dimensional than in two-dimensional photonic crystals. This is because of more difficult fabrication. [22]
The approximation holds for particles of arbitrary shape that are relatively small but can be larger than Rayleigh scattering limits. [1] The theory was derived by Lord Rayleigh in 1881 and was applied to homogeneous spheres, spherical shells, radially inhomogeneous spheres and infinite cylinders. Peter Debye has contributed to the theory in 1881.
The properties of colloidal gold nanoparticles, and thus their potential applications, depend strongly upon their size and shape. [10] For example, rodlike particles have both a transverse and longitudinal absorption peak, and anisotropy of the shape affects their self-assembly .
The Tyndall effect is light scattering by particles in a colloid such as a very fine suspension (a sol). Also known as Tyndall scattering , it is similar to Rayleigh scattering , in that the intensity of the scattered light is inversely proportional to the fourth power of the wavelength , so blue light is scattered much more strongly than red ...
A colloid is stable if the interaction energy due to attractive forces between the colloidal particles is less than kT, where k is the Boltzmann constant and T is the absolute temperature. If this is the case, then the colloidal particles will repel or only weakly attract each other, and the substance will remain a suspension.