1. Generate some numbers for scattering cross sections using the equations given. | ||
Look, e.g., at "air" molecules including some water vapor or ozone as scatterers, and wave lengths from the IR to the UV. | ||
2. Derive or justify the equation l_{sc} = 1/ns. Show that for air we get l_{sc} (=) 160 · l^{4} if we give l in km and l in µm. | ||
Hint 1: Consider the particle to be a cube with s being the area of a face. All light will be scattered if the total area of those cubes projected
on a surface perpendicular to the light beam covers that area completely. l_{sc}
then is the length of a cube that contains enough particle to meet that condition. Hint 2: The volume of an air "molecule" can be estimated from the fact the liquid air has about the same density as water. | ||
3. Generate some numbers for penetration depths in air. How thick does an ozone (O_{3}) layer with a density n_{Oz} = 8 ml/m^{3} have to be to absorb most of the incoming ultraviolet radiation (especially "UV-B"; l » 300 nm) | ||
Link to the solution |
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5.2.5 Not so Perfect Materials
Complex Index of Refraction of Silicon
Solution to 5.2-3: Attenuation of Light
Solution to Exercise 5.2-3: Rayleight Scattering
© H. Föll (Advanced Materials B, part 1 - script)