REFLECTANCE OF IR RADIATION FROM HIGH ABSORBING LAYER OF ULTRA-FINE METALLIC PARTICLES

The IR radiation reflectance is calculated of a thin (with the thickness of an order of vacuum wave length lambda) layer of small metallic particles. Before, we have shown that such a layer of a small particles density absorbes nearly entirely all the incident radiation in a wide IR wavelength range. The effect is connected with the free penetration of the ac field into the quasimetallic high-dispersive medium and is caused by the resonant excitation of surface electromagnetic waves in nonspherical metallic particles. The reflectance of the incident radiation from a layer turns out to be small as defined by a parameter sigma(s)/sigma(a), where sigma(s) and sigma(a) are scattering and absorption cross-sections by a single particle, respectively. The reflectance by an order of magnitude is equal to (V/lambda(3))\epsilon\, where V is the particle's volume; epsilon is the dielectric function of a metal. In a typical experimental situation the reflectance amounts to no more than several percents of incident radiation.