Changes in the optical properties of two gold nanoparticles caused by different connection types

The goal of our paper was to investigate the impact of the necking phenomenon on the optical properties of two gold nanoparticles characterized by a large value of the imaginary part of the refractive index m. Our results show that the difference between various neck types is small, therefore, for the modeling process, we recommend the most simple one, i.e. the cylindrical connector. When a connection between two primary particles is caused by the overlap factor C-ov, and not by the neck size parameter Y-con, the results can be much more erroneous and the possible error should be at least taken into consideration. The position of the extinction peak in a function of the connection size C-ov is dependent on the value of the complex refractive index m. Additionally, the applicability of the DDA (Discrete Dipole Approximation) method for measuring the extinction cross section C-ext of gold structures was studied.