Radio frequency absorption in gold nanoparticle suspensions: a phenomenological study

Detailed calculations of the attenuation of low-frequency electromagnetic fields and dielectric losses by a dilute suspension of gold colloidal nanoparticles are reported. The attenuation produced by the particles suspended in an aqueous medium of low electrolyte concentration was found to be modest as compared with the attenuation in the medium itself. The same result is obtained using the Maxwell-Wagner effective medium theory with the effect of the counter-ion relaxation also taken into account. The attenuation associated with the motion of the colloidal particles under the effect of the electric field has also been evaluated and found significant under certain conditions. This study points towards the importance of the ionic contribution and the motion of the charged nanoparticles as key factors for the increased absorption observed at radio frequencies in dilute suspensions of gold colloidal nanoparticles.