Nonuniformity of electromagnetic field at Lambda = 10.6 micron wavelength inside atmospheric aerosol particles

Probing of the atmosphere with a CO2 laser (lambda = 10.6 microns) is considered, absorption of optical radiation and emission of heat by solid atmospheric aerosol particles being analyzed on the basis of the Mie theory. The nonuniform radial distributions of electromagnetic field intensity and heat emission intensity are determined in the approximation of geometrical optics, assuming spherical particles. Calculations are made separately for weakly absorbing and strongly absorbing substances (Al2O3, ice, SiO2, MgO, NaCl, soot, graphite, coal), different treatment being required in each case for particles with radii smaller than the radiation wavelength (0.02 to 0.1 micron), for particles with radii comparable with the radiation wavelength, and for particles with radii larger than the radiation wavelength (30 to 60 microns). As a simplification covering the entire range is proposed focusing the radiation at the center of a spherical particle, assuming smaller than critical incidence angles and selecting the Brewster angle as critical in the case of a real refractive index or the zero-refraction angle as critical in the case of a complex refractive index.