Identification of single nanoparticles

The physicochemical properties of nanomaterials significantly depend on their three-dimensional (3D) morphologies (sizes, shapes and surface topography), the surrounding media, and their spatial arrangement. Systematically and precisely correlating these parameters with the related physicochemical properties of specific single nanoparticles (NPs) is a fundamental requirement for the discovery of their novel properties and applications, as well as for advancing the fundamental and practical knowledge required for the design and fabrication of new materials. In this article, the progress in the identification of the specific individual NP is summarized, including the in situ methods and the spatial-localization methods based on plasmonic NPs as model. Identification of single NPs based on local surface plasmon resonance observed by fluorescent inverted optical microscopy, dark-field microscopy, scanning near-field optical microscopy, atomic force microscopy, and transmission electron microscope are reviewed. Recent progress in the investigation of 3D morphology-dependent optical properties by these methods is described. Experimental and theoretical developments in single-NP identification for the purpose of understanding the physicochemical properties are discussed.