Molecular-mediated assembly of silver nanoparticles with controlled interparticle spacing and chain length

In the present work, we report on a one-pot method for the assembly of noble metal nanoparticles with tunable optical properties, assembly length and interparticle spacing. The synthetic colloidal route is based on the covalent binding among OH-terminated silver nanoparticles by means of dicarboxylic acids with a defined molecular length. As a result, the initially symmetric plasmon band of silver nanoparticles splits into two plasmonic modes when nanoparticles are assembled due to the strong near-field plasmon coupling. We noticed a very good correlation between the plasmon wavelength shift and the interparticle spacing that is represented by the universal scaling law of the surface plasmon resonance in metal nanoparticle dimers. A relationship between the plasmon coupling and the assembly size (represented by the number of nanoparticles) for two different interparticle distances has been experimentally found. Such a correlation has revealed the additional effect of the electronic polarizability of the linker on the propagation of the plasmon coupling between NPs.