Theoretical Analysis of the Optical Properties of Gold Nanoparticles Using DDA Approximation

   This article describes a study, using numerical simulation, of the optical properties of nano particles as a function of their size. Many methods introduced to simulate and calculate the interaction of light and particle, such as Mie analysis, boundary element and finite element methods. The Discrete Dipole Approximation (DDA), wherein a target geometry is modeled as a finite array of polarizable elements and DDSCAT simulation, are employed for determining extinction, absorption and scattering cross sections by gold nano particles with 15, 35, 55, 75, 100, 125 and 150 nanometers in diameter in different wavelengths. In this method, the particle is represented as a cubic array of electric dipoles. The results show that Plasmon resonance dependent on nano particles size. In other project, the angular distribution of different sizes of gold nano particles are calculated and scattering of these particles are compared. This study can be helpful in designing appropriately shaped nano particles for in-vivo applications like photo-thermal cancer treatment and optical sensors.