Modelled infrared extinction and attenuation performance of atmospherically disseminated high aspect ratio metal nanoparticles

Infrared extinction, scattering and absorption coefficients have been theoretically calculated for high aspect ratio micro and nano particles of several highly conducting metals. Two particle geometries have been modelled, thin disc flakes and thin fibres. Optimum particle minor dimensions on the nano scale for maximum infrared extinction and attenuation performance have been predicted for these two geometries, and the relative performance of different metals has been evaluated. Particle phase functions and polarization states of the scattered light have also been calculated, and their dependence on particle orientation has been studied. The extinction coefficient calculations have been performed using the infinite cylinder solution and the finite difference time domain (FDTD) method. Transmission and attenuation calculations were performed for various scenarios using the Beer-Lambert law, and the six-flux and spherical harmonics methods of solving the full radiative transfer equation (RTE) for an absorbing and scattering medium. Of the metals studied, aluminium and brass particles are predicted to be the best potential attenuators of infrared radiation. The maximum possible volume extinction coefficients and required particle dimensions are calculated for aluminium and brass particles of both geometries.