Elastic extinction

The trace of the planar central zone of the microcrack-ladder is marked by the presence of negative crystals and inclusions. This characteristic indicates that microcrack-ladders must be related to healed longitudinal fractures. The formation of unhealed microcracks normal to the loading direction (i.e., the rungs of the ladders) can be understood as follows. Undulatory extinction and dislocation microstructures observed within the microcrack-ladders indicate that plasticity is restricted to a narrow zone ( 100 / m wide) within the otherwise-undeformed host crystal. Therefore, the host crystal responded elastically while the load was applied the elastic strain A/// being about 0.5 percent. Now, in the plastic zone of the... 

The attenuation of light by a particle includes contributions from elastic scattering and absorption. The absorbed photons induce transitions leading to Raman or fluorescence scattering or contribute to the internal heating of the particle. The extinction cross section is the sum of the elastic-scattering cross section and the absorption cross section. The corresponding efficiency factors formed by... 

When the refractive index is real, the real part of each scattering amplitude equals the square of its magnitude, the extinction and elastic-scattering efficiency are identical, and the absorption efficiency is zero. The elastic-scattering ef-... 

In the Raman lidar technique, both the elastically and inelasticaUy scattered radiation contents are recorded. Elastically scattered radiation depends on both molecular and particulate species in contrast, inelastic scattering depends only on molecular scattering. The ratio of the two signals yields a parameter called the aerosol scattering ratio (ASR), which constitutes a rough measure of the concentration of aerosols. An example for an ASR measurement is shown in Figure 28.27. From the available data one can extract both the extinction and back-scattering coefficients. 

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