Photophoresis and the scattering of electromagnetic radiation
Abstract
Electron-microscope photographs of soot lend support to the picture in which a soot particle is modeled as a collection of chains of small carbon spheres. The soot particle itself is typically considerably larger than the small carbon spheres making up the chains. Thus the soot particles might have a size approx. 0.1 - 1 microns while the small carbon spheres might have a size approx. 0.03 microns in typical situations. Further, measurements of the density of soot yield values much less than that of normal carbon, indicating that an individual soot particle has a rather small filling factor, i.e., the fraction of the volume of the particle that is occupied by chains. If a soot particle is taken to be a sphere partially filled with carbon chains, what are its scattering and absorption properties. Several workers have adopted the view that the net scattering and absorption properties can be determined simply by summing the cross-sections for the individual small carbon spheres. It appears that in a first rough approximation the scattering and absorption properties of soot can be determined by estimating the effective dielectric constant of a soot sphere.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- September 1985
- Bibcode:
- 1985STIN...8620766I
- Keywords:
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- Dielectric Properties;
- Electron Microscopy;
- Microstructure;
- Photophoresis;
- Soot;
- Absorption Spectra;
- Density (Mass/Volume);
- Electromagnetic Radiation;
- Scattering;
- Instrumentation and Photography