Second-Harmonic Scattering-Defined Topological Classes for Nano-Objects

Abstract

Nano-objects topology determination is a central question in nano-science and remains a challenge to achieve in absence of supporting substrate and atomic resolution techniques. In this work, we demonstrate how second harmonic scattering is sensitive to the balance between the nano-objects shape symmetry and size, thereby allowing for a second harmonic scattering defined topological definition. Although many data on nano-objects have been reported with this method so far, in most cases dispersed in liquid suspensions, no topological retrieval has been proposed. To reach this task, we have measured the second harmonic scattered light from a series of representative nano-objects along two collection directions for well-defined polarization states. The experimental results are then recast within a general framework involving nonlinear emitting sources and the size as critical elements. This analysis leads to the classification of the nano-objects according to the topology defined by their second harmonic scattering response. Current Size (2726 words) Nano-objects topology determination is a central question in nano-science and remains a challenge to achieve in absence of supporting substrate and an atomic resolution techniques like electron microscopy [1, 2]. With the fast development of the design and engineering of nano-objects aiming for many different applications, from functional materials to sensors, nanoprobes for microscopy or nanocapsules for drug delivery, the fine physical details of these nano-objects must be determined precisely [3]. Among these structure parameters, one may identify the material nature, the size, the shape or the morphology. In the latter case, plain solid or core-shell nanostructures for example can yield very different properties with great variety, notably in nano-optics. The shape of the nano-objects is likewise also a critical parameter.