Mesoscopic linear alignment and thermal-relaxation dynamics of aggregated gold nanorods

Abstract

Aqueous gold nanorod colloids aggregated by Cl- are further assembled into linearly aligned structures of linear bundles during evaporation on TEM grids. Gold nanorods in bundles are also oriented in nearly head-to-tail shapes in the microscopic scale. Induced dipolar long-range interactions in the mesoscopic scale are suggested to drive gold nanorods to aggregate. Although surface-plasmon absorption at transverse resonances decreases, that at longitudinal resonances increases with aggregation. The photon-thermalized heat of the dispersed and the aggregated gold nanorods dissipates to immediately surrounding media on the time scales of 100 and 800 ps, respectively.