Radiation Scattering by Fractal Clusters in AerosolsEPA Grant Number: R822658
Title: Radiation Scattering by Fractal Clusters in Aerosols
Investigators: Shalaev, Vladimir M. , Goedecke, George
Institution: New Mexico State University - Main Campus
EPA Project Officer: Hiscock, Michael
Project Period: October 15, 1995 through October 14, 1997
Project Amount: $95,461
RFA: Exploratory Research - Minority Institutions (1995) Recipients Lists
Research Category: Water , Land and Waste Management , Ecosystems , Air , Aquatic Ecosystems
Description:In this project, a theory of radiation extinction and scattering by complex aerosols having fractal structure is proposed to develop. The proposed research is aimed at building a model of light scattering for pollution identification and characterization. The effect of radiation scattering by fractal pollutants on the environment will be also studied in the present project. Specifically, the following studies are proposed: the resonant and nonresonant scattering and absorption by fractal clusters in the atmosphere such as smoke, metal aerocolloidal aggregates and some biological macromolecules and chemical compounds having fractal structure. All these objects are aggregates of small particles which have combined into sparse random fractal clusters.
The main objective of this project is to develop the fluctuation theory of the scattering by fractal objects in the atmosphere. Such a new theory will take into account the fractal morphology and the strong fluctuations associated with the fractality. A renormalization analysis of the field fluctuations within a cluster will be used to build the theory. The results obtained will be applied to identification of pollutants having fractal structure.
To develop the optics of fractals such as smoke is important for solution of environmental problems caused by the extinction and scattering from soot clusters lofted into the atmosphere by diesel engines, industrial stacks and large fires and, in particular, from those produced by multiple nuclear explosions. Closely connected with these problems is the greenhouse effect.
To study radiation scattering by such complex man-made aerosols as aerocolloidal metal aggregates, fractal chemical compounds and biological macromolecules is of interest for remote detection of airborne chemical and biological agents in the atmosphere. If particles forming a cluster possess a resonance with a high quality-factor, then localized zones of high fields are induced in the fractal cluster under the resonant excitation. These "hot" zones are associated with excitation of collective dipolar eigenmodes which appear to be strongly localized within areas smaller than the wavelength. The domains of high fields result ultimately in greatly enhanced scattering. A point of emphasis in the proposed study of the resonant scattering from complex aerosols will be the fluctuations which play especially important role when exciting the resonant eigenmodes of fractal pollutants. The proposed research is expected to contribute to development of a model for remote identification and characterization of pollution. Specifically, a comprehensive theory of radiation scattering and absorption by complex aerosols having irregular chain-like morphology such as soot clusters and some biological and chemical pollutants will be developed.