Modeling nanoporous gold plasmonic nanoparticles: Calculation of optical properties

Maxwell-Garnett effective medium theory (MG-EMT) has been employed to model disk shaped nanoporous gold nanoparticles (NPG nanoparticles or NPG Disks). Optical properties of these nanoparticles have been calculated using the proposed model via Finite Difference Time Domain (FDTD) method. Calculated optical properties reflect strong dependence on particle dimensions. The resonant extinction wavelength (λRes) can be tuned from ~600 to ~1300 nm by changing the particle diameter from 100 to 500 nm while the thickness is fixed at 75 nm; λRes can be blue shifted from ~600 to ~550 nm by varying the thickness from 25 to 100 nm for 100 nm diameter particles. Among these particle dimensions, the maximum scattering coefficient has been found in 200 nm diameter and 25 nm thick nanoparticles, while the maximum absorption coefficient in 100 nm diameter and 25 nm thick nanoparticles.