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Database of Optical Properties -- Level: subpage


Optical properties of porous particles (part II)




The following figures show the behaviour of the efficiency factors Qext, Qsca, Qabs as well as albedo Λ and asymmetry parameter g for porous particles. Calculations are performed for pseudospheres having inclusions of different sizes (both Rayleigh and non-Rayleigh ones) using the discrete dipole approximation. These optical characteristics are compared with results of Lorenz-Mie calculations for corresponding n-layered spheres.

The refractive indices of inclusions are:
    1.200+0.000i ((biological particles in the visual part of the spectrum),
    1.330+0.010i (dirty ice),
    1.578+1.038i (center of the 10 micron silicate feature),
    1.680+0.030i (silicate),
    1.750+0.058i (soot),
    1.980+0.230i (amorphous carbon).

The porosity of particles (the volume fraction of vacuum) is P = 0.33 and P = 0.9. For given porosity the particles of the same size parameter xporous have the same mass (see for more details Voshchinnikov et al., 2007) and are compared in the following figures organized in the tables.




refractive index = 1.20+0.00i
P=0.33 P=0.9
factors
Qext(x)
Qsca(x)
g(x)
factors
Qext(x)
Qsca(x)
g(x)




refractive index = 1.33+0.01i
P = 0.33 P = 0.9
factors
Qext (x)
Qsca (x)
Qabs (x)
g(x)
albedo (x)
factors
Qext (x)
Qsca (x)
Qabs (x)
g (x)
albedo (x)


refractive index = 1.578+1.0381i
P=0.33 P=0.9
factors
Qext(x)
Qsca(x)
Qabs(x)
g(x)
albedo(x)
factors
Qext(x)
Qsca(x)
Qabs(x)
g(x)
albedo(x)

refractive index = 1.68+0.03i
P=0.33 P=0.9
factors
Qext(x)
Qsca(x)(x)
Qabs(x)
g(x)
albedo(x)
factors
Qext(x)
Qsca(x)
Qabs(x)
g(x)
albedo(x)


refractive index = 1.75+0.58i
P=0.33 P=0.9
factors
Qext(x)
Qsca(x)
Qabs(x)
g(x)
albedo(x)
factors
Qext(x)
Qsca(x)
Qabs(x)
g(x)
albedo(x)


refractive index = 1.98+0.23i
P=0.33 P=0.9
factors
Qext(x)
Qsca(x)
Qabs(x)
g(x)
albedo(x)
factors
Qext(x)
Qsca(x)
Qabs(x)
g(x)(x)
albedo(x)


For more information, see the papers:

N. V. Voshchinnikov, V. B. Il'in, and Th. Henning, Modelling the optical properties of composite and porous interstellar grains, Astronomy and Astrophysics, 429, 371-381, 2005.

Nikolai V. Voshchinnikov, Gorden Videen, and Thomas Henning, Effective medium theories for aggregate structures: agglomeration of small parti- cles, Applied Optics, 46, 4065-4072, 2007.

N. N. Zavyalov, N. V. Voshchinnikov, Scattering of light by fluffy aggregates consisting of small and large particles, In: Eleventh Conference on Electromagnetic and Light Scattering, edited by J. Hough (Hartfield, 2008), pp. 113-116.