Invisibility of plasmonic nanoparticles in THz region

Platinum (Pt) nanoparticles with diameters d less than 10 nm are almost invisible to THz radiation. However, they demonstrates high absorption in infrared (IR) and visible region. Mie scattering theory under the assumption of d far less than λ, suggests the prominent inhibition of absorption and scattering due to the long wavelength character and the extremely large imaginary part of the dielectric function of Pt in THz region. The results are useful for THz photonics as dichromic filters for THz telecommunication.