Structural and optical properties of gold nanosponges revealed via 3D nano-reconstruction and phase-field models

• Published in: Communications materials Vol. 4; no. 1; pp. 20 - 13
• Main Authors: Grunert, Malte, Bohm, Sebastian, Honig, Hauke, Wang, Dong, Lienau, Christoph, Runge, Erich, Schaaf, Peter
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 08.03.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/1019/1021; 639/301/357; Anisotropy; Chemistry and Materials Science; Ion beams; Materials Science; Morphology; Nonlinear optics; Nonlinear response; Optical properties; Physical properties; Reconstruction; Sponges; Tomography
• ISSN: 2662-4443; 2662-4443
• DOI: 10.1038/s43246-023-00346-7

Nanosponges are subject of intensive research due to their unique morphology, which leads among other effects to electrodynamic field localization generating a strongly nonlinear optical response at hot spots and thus enable a variety of applications. Accurate predictions of physical properties require detailed knowledge of the sponges’ chaotic nanometer-sized structure, posing a metrological challenge. A major goal is to obtain computer models with equivalent structural and optical properties. Here, to understand the sponges’ morphology, we present a procedure for their accurate 3D reconstruction using focused ion beam tomography. Additionally, we introduce a simulation method to create nanoporous sponge models with adjustable geometric properties. It is shown that if certain morphological parameters are similar for computer-generated and experimental sponges, their optical response, including magnitudes and hot spot locations, are also similar. Finally, we analyze the anisotropy of experimental sponges and present an easy-to-use method to reproduce arbitrary anisotropies in computer-generated sponges. Accurate predictions of nanosponge properties are challenging as it requires detailed knowledge of their chaotic structure. Here, a procedure for their accurate 3D reconstruction is presented using focused ion beam tomography with simulations to create models with adjustable geometric properties.