LAUSR

Abstract We are proposing a novel method to form thin films that are composed of ordered arrays of iron-gold core-shell (Fe@Au) nanoparticles with tunable optical responses. The method is based on the crosslinking of the adjacent Fe@Au nanoparticles using bifunctional group organic molecules. Molecules of m-phenylenediamine (MPD) as conjugated diamines can crosslink the adjacent Fe@Au nanoparticles. Experimental results show that the larger the Fe@Au/MPD mass ratio, the more intense the corresponding plasmon resonance. Images of the optical microscopy and FE-SEM show that there is a tradeoff between the Fe@Au/MPD mass ratio and the formation of ordered arrays of Fe@Au nanoparticles. In particular, Fe@Au/MPD ≈ 0.4% is the optimum mass ratio for forming long-chain arrays of Fe-Au core-shell nanoparticles. Moreover, the results of optical spectroscopy show that the absorbance spectrum of the optimum sample strongly depends on the incoming light polarization, making it a good nominee for optical grating. Finally, a comparison of the Kerr rotations for the optimum sample and the one with an excessive number of cross-linking molecules confirms that the nanoparticles in the latter sample, unlike in the optimum sample, are more densely packed and could not form the ordered arrays.