Light, absorption particle character

Modern atomic theory received a shot in the arm when it was recognized that the individual atom has light absorption and emission spectra occurring at narrow lines of the spectrum at specific wavelengths, as opposed to the broad bands typical of the polyatomic molecules and compounds. Since the line spectrum of each element is characteristic of that element, atomic spectroscopy can be used for precise elementary analysis of many types of chemically simple and complex materials. These studies make use of the wave character of light, as well as light s particle character. 

In this case the initial act of light absorption leads to the formation of an exciton, rather than a free electron or hole. Such an exciton, as it wanders through the crystal, may meet a lattice defect and annihilate on it, the energy of the exciton being utilized to ionize the defect, i.e., to transfer an electron or hole localized on the defect to the free state (the mechanism of Lashkarev-Juze-Ryvkin, see 90, 91). If such a defect is a foreign particle chemisorbed on the crystal surface, the result will be a change in the character of the bond between this particle and the surface. Thus, the interaction of the lattice excitons with the chemisorbed particles may cause a change in the relative content of the different forms of chemisorption and... 

The propagation of light in multiple scattering media is quantified usually on the level of radiative transfer or particle diffusion. Scattering, absorption, and emission are considered as independent statistical processes, and the consequences of wave character are either ignored, like polarization, or added as an additional parameter, like the phase function P(ji n) that describes the angular distribution of scattered... 

As previously discussed, the performance of white LEDs using conventional phosphors suffers om several limitations due to the intrinsic properties of most phosphor materials. The fixec absorption and emission character of conventional phosphors is an intrinsic property that has posec challenges to a variety of display and lighting applications. When used to create white LEDs, conventional micron-sized phosphor tends to scatter light which reduces the LED s overall efficiency The size of these particles also results in non-homogeneous light output from each lamp. 

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