Cluster formation by the precise joining of iron oxide nanoparticles on low energy nitrogen ion irradiation

In this work, we have studied low-energy (5 keV) nitrogen ion-induced modification of the surface of iron oxide nanoparticles. The iron oxide nanoparticles were spin-coated on a silicon substrate. The thin films of iron oxide nanoparticles were irradiated at two different ion fluences of 1 x 10(16) and 3 x 10(16) ions cm(-2), respectively. At a fluence of 1 x 10(16) ions cm(-2), the nanoparticles incline to join with each other forming small clusters which can be attributable due to Ostwald ripening because of the ion-induced defects. At higher fluence of 3 x 10(16) ions cm(-2), large nanoclusters are formed due to coalescence. We have investigated the morphological and structural properties of both the pristine and altered surface in detail to understand the cluster formation. We anticipate that such reformed surfaces can be beneficial to enhance the surface plasmon resonance.