Three-dimensional nanoscale imaging by plasmonic Brownian microscopy

Abstract

Three-dimensional (3D) imaging at the nanoscale is a key to understanding of nanomaterials and complex systems. While scanning probe microscopy (SPM) has been the workhorse of nanoscale metrology, its slow scanning speed by a single probe tip can limit the application of SPM to wide-field imaging of 3D complex nanostructures. Both electron microscopy and optical tomography allow 3D imaging, but are limited to the use in vacuum environment due to electron scattering and to optical resolution in micron scales, respectively. Here we demonstrate plasmonic Brownian microscopy (PBM) as a way to improve the imaging speed of SPM. Unlike photonic force microscopy where a single trapped particle is used for a serial scanning, PBM utilizes a massive number of plasmonic nanoparticles (NPs) under Brownian diffusion in solution to scan in parallel around the unlabeled sample object. The motion of NPs under an evanescent field is three-dimensionally localized to reconstruct the superresolution topology of 3D dielectric objects. Our method allows high throughput imaging of complex 3D structures over a large field of view, even with internal structures such as cavities that cannot be accessed by conventional mechanical tips in SPM.

Imaging of Nanoscale Light Confinement in Plasmonic Nanoantennas by Brownian Optical Microscopy

“…More recently, diffusive fluorescent molecules in solution have been introduced in these SML based microcopies to map out a wide field of view of local electromagnetic fields near the rough metallic surface, ,− nanoisland, and tridisk spaced by 30 nm gaps . It is worth noting that the Brownian diffusion of plasmonic nanoparticles in solution has also been utilized to scan the topology of 3D dielectric objects . Nevertheless, these Brownian-diffusion-based optical microscopies are still in their infancy, and thus more explorations are needed, for example, investigation of their capabilities in polarization sensitivity and tunability of molecular localization near PNAs.…”

“…27 It is worth noting that the Brownian diffusion of plasmonic nanoparticles in solution has also been utilized to scan the topology of 3D dielectric objects. 28 Nevertheless, these Brownian-diffusion-based optical microscopies are still in their infancy, and thus more explorations are needed, for example, investigation of their capabilities in polarization sensitivity and tunability of molecular localization near PNAs.…”