Search results
Results from the WOW.Com Content Network
The exact reverse of radiative recombination is light absorption. For the same reason as above, light with a photon energy close to the band gap can penetrate much farther before being absorbed in an indirect band gap material than a direct band gap one (at least insofar as the light absorption is due to exciting electrons across the band gap).
A. R. Forouhi and I. Bloomer deduced dispersion equations for the refractive index, n, and extinction coefficient, k, which were published in 1986 [1] and 1988. [2] The 1986 publication relates to amorphous materials, while the 1988 publication relates to crystalline.
[1]: 128 It is related to the absorption coefficient, , through: [39]: 41 = These values depend upon the frequency of the light used in the measurement. That κ corresponds to absorption can be seen by inserting this refractive index into the expression for electric field of a plane electromagnetic wave traveling in the x -direction.
This is usually silica, which has a much lower refractive index (of about 1.44 in the wavelength region of interest [63]), and thus light at the silicon-silica interface will (like light at the silicon-air interface) undergo total internal reflection, and remain in the silicon. This construct is known as silicon on insulator.
Absorption indicates energy that is lost from the beam, while scattering indicates light that is redirected in a (random) direction, and hence is no longer in the beam, but still present, resulting in diffuse light. The absorption coefficient of a volume, denoted μ a, and the scattering coefficient of a volume, denoted μ s, are defined the ...
An overview of absorption of electromagnetic radiation.This example shows the general principle using visible light as a specific example. A white light source—emitting light of multiple wavelengths—is focused on a sample (the pairs of complementary colors are indicated by the yellow dotted lines).
Thus a scattering coefficient μ s and an absorption coefficient μ a can be combined into a total extinction coefficient μ = μ s + μ a. [ 6 ] Importantly, Beer also seems to have conceptualized his result in terms of a given thickness' opacity, writing "If λ is the coefficient (fraction) of diminution, then this coefficient (fraction) will ...
Many materials have a well-characterized refractive index, but these indices often depend strongly upon the frequency of light, causing optical dispersion. Standard refractive index measurements are taken at the "yellow doublet" sodium D line, with a wavelength (λ) of 589 nanometers.