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The propagation of radiation through a medium is affected by absorption, emission, and scattering processes. The equation of radiative transfer describes these interactions mathematically. Equations of radiative transfer have application in a wide variety of subjects including optics, astrophysics, atmospheric science, and remote sensing.
The Elliott formula describes analytically, or with few adjustable parameters such as the dephasing constant, the light absorption or emission spectra of solids. It was originally derived by Roger James Elliott to describe linear absorption based on properties of a single electron–hole pair. [ 1 ]
The absorption coefficient for spectral flux (a beam of radiation with a single wavelength, [W/m 2 /μm]) differs from the absorption coefficient for spectral intensity [W/sr/m 2 /μm] used in Schwarzschild's equation. Integration of an absorption coefficient over a path from s 1 and s 2 affords the optical thickness (τ) of that path, a ...
Absorbance is defined as "the logarithm of the ratio of incident to transmitted radiant power through a sample (excluding the effects on cell walls)". [1] Alternatively, for samples which scatter light, absorbance may be defined as "the negative logarithm of one minus absorptance, as measured on a uniform sample". [2]
A different form of the equation is sometimes used for certain types of materials, e.g. crystals. Each term of the sum representing an absorption resonance of strength B i at a wavelength √ C i. For example, the coefficients for BK7 below correspond to two absorption resonances in the ultraviolet, and one in the mid-infrared region.
Thus a net power is released into the electric field equal to the photon energy hν times this net transition rate. In order for this to be a positive number, indicating net stimulated emission, there must be more atoms in the excited state than in the lower level: >. Otherwise there is net absorption and the power of the wave is reduced during ...
Neutron transport (also known as neutronics) is the study of the motions and interactions of neutrons with materials. Nuclear scientists and engineers often need to know where neutrons are in an apparatus, in what direction they are going, and how quickly they are moving.
Defining equation (physical chemistry) List of electromagnetism equations; List of equations in classical mechanics; List of equations in quantum mechanics; List of equations in wave theory; List of photonics equations; List of relativistic equations; Relativistic wave equations