Nanoscale Writing of Gold Nanoparticle Assemblies at the Liquid-Vapor Interface Using a Focused Electron Beam

The electron beam of an environmental scanning electron microscope is used to manipulate gold nanoparticles (AuNPs) at the liquid-vapor interface of their aqueous dispersion. Controlled motion and agglomeration of AuNPs into larger structures is achieved, enabling the writing of superstructures that float at the interface. AuNPs move toward the electron beam, independent of zeta potential, and the spatial range at which this attraction acts is much larger than what is possible for electrostatic interactions. The speed of agglomerate growth depends on the applied electron flux, and electron beam energy. The hypothesis that this electron beam-induced AuNP assembly process is caused by local liquid evaporation upon electron beam heating is presented.