Radiative characterisation of small heterogeneous particles
Model heterogeneous particle exposed
to an external plane electromagnetic wave.
The effects of pore-level geometry
on direction-averaged radiative properties
of small heterogeneous particles encountered in solar thermochemical
applications such as three-dimensionally ordered macro-porous
(3DOM) cerium dioxide (ceria) particles are investigated
in the UV, VIS and IR spectral ranges, typically 0.3–10 μm.
The porous particles are modeled as three-dimensional arrays
of interacting dipoles using the discrete dipole approximation (DDA).
Reference solutions are obtained by directly solving Maxwell's equations.
Validity ranges of the Lorenz–Mie theory to predict
far-field radiative properties of quasi-homogeneous particles
with the effective optical properties obtained using the volume-averaging
theories (VAT) are established.
The properties of interest are the spectral extinction, scattering,
and absorption efficiency factors as well as the scattering phase function
and the scattering asymmetry factor.