Linear aggregation of gold nanoparticles in ethanol

Gold colloidal particles were found to spontaneously organize into linear aggregates in ethanol. The morphology of these aggregates was characterized with transmission electron microscope (TEM) and atomic force microscope (AFM), which revealed the quasi one-dimensional (1D) chain-like shape. Immobilization of these chains from solution onto substrate surface as well as the measurement of UV–visible extinction spectrum was performed to investigate the aggregation mechanism. The results presented the evidence for the existence of the nanoparticle chains in solution. Moreover, the kinetic aspects of the chain-like aggregation were detailed studied using UV–visible spectroscopy. It is believed that dipole–dipole interaction is the driving force of nanoparticle linear aggregation. This finding provides a novel strategy for the construction of quasi 1D structures, which are suitable for the fabrication of solid-state devices based on single-electron tunneling.