Absorption Efficiency Factor Research Articles

Planck mean absorption efficiency for amorphous carbon and graphite grains

Planck mean absorption efficiency factors for amorphous carbon and graphite grains have been computed using experimentally determined optical properties. The effective temperature used in calculating these means ranges from 10 to 1800 K.

Efficiency Factors in Mie Scattering

Asymptotic approximations to the Mie efficiency factors for extinction, absorption, and radiation pressure, derived from complex-angular-momentum theory and averaged over $\ensuremath{\Delta}\ensuremath{\beta}\ensuremath{\sim}\ensuremath{\pi}$ ($\ensuremath{\beta}=\mathrm{size}\mathrm{parameter}$), are given and compared with the exact results. For complex refractive indices $N=n+ik$ with $1.1<~n<~2.5$ and $0<~k<~1$, the relative errors decrease from \ensuremath{\sim}(1-10)% to \ensuremath{\sim}(${10}^{\ensuremath{-}2}$-${10}^{\ensuremath{-}3}$)% between $\ensuremath{\beta}=10$ and $\ensuremath{\beta}=1000$, and computing time is reduced by a factor of order $\ensuremath{\beta}$, so that the Mie formulae can advantageously be replaced by the asymptotic ones in most applications.

Internal field resonance structure: Implications for optical absorption and scattering by microscopic particles

Mie scattering theory is used to calculate the efficiency factors for absorption by microscopic dielectric spheres. Resonances in the efficiency factors for absorption and resonances in the amplitudes of the electric and magnetic multipoles which occur in an expansion of the fields inside the dielectric sphere are discussed. Several trends in the strengths and width of the various resonances as functions of the absorption coefficient of the sphere, size parameter, multipole order, and multipole resonance number are given. A formal solution for elastic (Mie) and inelastic (Raman) scattering by microscopic particles is derived from the extinction theorem. With this background, some implications of the resonances in the interpretation of absorption, fluorescence, and Raman scattering by microscopic particles are discussed.

Resonances in the efficiency factors for absorption: Mie scattering theory

Resonances in the efficiency factors for absorption: Mie scattering theory

5.5 Temperature Distribution and Lifetime of Interplanetary Ice Grains

AbstractAn improved solution of the temperature distribution of interplanetary ice grains is presented using the refractive index measured at 100° K. The efficiency factors for absorption are obtained from Mie theory and the calculation is carried out for micronic and submicronic grains at 50, 100 and 150° K; corresponding lifetimes are given.

Variation of Single Particle Mid-Infrared Emission Spectrum with Particle Size

The emission spectra of single particles of inorganic solids as a function of particle size have been recorded from 6 micro to 11.8 micro. For small optically thin particles, an emission maximum is produced in the reststrahlen region. The emission behavior is dominated by scattering and can be adequately described in terms of Mie absorption efficiency factors. As the particle size is increased, the emission band reverses its polarity, and the spectrum approaches that of a polished plate. The data provide source functions necessary for determining the emission behavior of particulate samples in which temperature gradients exist, such as on the lunar surface. The data are of particular interest for interpreting the spectral behavior of circumstellar silicate particles.

Optical Efficiency Factors for Concentric Spheres

Extinction, scattering, and absorption efficiency factors for a concentric sphere of a nonlight absorbing nucleus (m = 1.5) and an absorbing shell (m = 1.95 - 0.66i) were calculated based on the theory of Aden and Kerker. For small size parameters (v < 1), the magnitude of the extinction efficiency factor is markedly affected by the shell thickness. An approximating equation, based on the Rayleigh light scattering equation, is presented which relates the increase of the extinction efficiency factor of an absorbing sphere over the extinction efficiency factor of a nonabsorbing sphere to the pertinent variables (refractive index and size parameter).

Mie Scattering and Absorption Cross Sections for Absorbing Particles

The Mie scattering and absorption cross sections for spherical particles are calculated as a function of the complex index of refraction, n = n(1) - in(2). Curves of the efficiency factors for absorption, scattering, and extinction are given for n(1) = 1.01, 1.33, 1.5, and 2 and for n(2) = 10(-4), 10(-2), 10(-1), 1, and 10. The influence of the absorption on the efficiency factors is discussed. The results are compared with previously proposed simplified expressions for these factors. The variation of the scattered intensity with angle as n(2) is varied is illustrated in some typical cases. Finally the influence of n(2) on the narrow resonances which occur for large values of n(1) is discussed.