Three-dimensional (3D) nanoframe structures are very appealing because their inner voids and ridges interact efficiently with light and analytes, allowing for effective optical-based sensing. However, the realization of complex nanoframe architecture with high yield is challenging because the systematic design of such a complicated nanostructure lacks an appropriate synthesis protocol. Here, we show the synthesis method for complex 3D nanoframes wherein two-dimensional (2D) dual-rim nanostructures are engraved on each facet of octahedral nanoframes. The synthetic scheme proceeds through multiple executable on-demand steps. With Au octahedral nanoparticles as a sacrificial template, sequential processes of edge-selective Pt deposition and inner Au etching lead to Pt octahedral mono-rim nanoframes. Then, adlayers of Au are grown on Pt skeletons via the Frank-van der Merwe mode, forming sharp and well-developed edges. Next, Pt selective deposition on both the inner and outer boundaries leads to tunable geometric patterning on Au. Finally, after the selective etching of Au, Pt octahedral dual-rim nanoframes with highly homogeneous size and shape are achieved. In order to endow plasmonic features, Au is coated around Pt frames while retaining their geometric shape. The resultant plasmonic dual-rim engraved nanoframes possess strong light entrapping capability verified by single-particle surface-enhanced Raman scattering (SERS) and show the potential of nanoprobes for biosensing through SERS-based immunoassay.
Using hybrid bilayer systems comprising a molecular organic semiconductor and silicon, we achieve optically controllable active terahertz (THz) modulators that exhibit extremely high modulation efficiencies. A modulation efficiency of 98% is achieved from thermally annealed C60/silicon bilayers, due to the rapid photo-induced electron transfer from the excited states of the silicon onto the C60 layer. Furthermore, we demonstrate the broadband modulation of THz waves. The cut-off condition of the system that is determined by the formation of efficient charge separation by the photo-excitation is highly variable, changing the system from insulating to metallic. The phenomenon enables an extremely high modulation bandwidth and rates of electromagnetic waves of interest. The realization of near-perfect modulation efficiency in THz frequencies opens up the possibilities of utilizing active modulators for THz spectroscopy and communications.
The development of plasmonic nanostructures with intricate nanoframe morphologies has attracted considerable interest for improving catalytic and optical properties. However, arranging multiple nanoframes in one nanostructure especially, in a solution phase remains a great challenge. Herein, we show complex nanoparticles by embedding various shapes of three-dimensional polyhedral nanoframes within a single entity through rationally designed synthetic pathways. This synthetic strategy is based on the selective deposition of platinum atoms on high surface energy facets and subsequent growth into solid platonic nanoparticles, followed by the etching of inner Au domains, leaving complex nanoframes. Our synthetic routes are rationally designed and executable on-demand with a high structural controllability. Diverse Au solid nanostructures (octahedra, truncated octahedra, cuboctahedra, and cubes) evolved into complex multi-layered nanoframes with different numbers/shapes/sizes of internal nanoframes. After coating the surface of the nanoframes with plasmonically active metal (like Ag), the materials exhibited highly enhanced electromagnetic near-field focusing embedded within the internal complicated rim architecture.
Transmittances of terahertz (THz) pulses through organic copper phthalocyanine (CuPc) films on Si were investigated under optical carrier excitation. As the external laser power increases, the difference between transmitted energies of THz pulses along the forward (CuPc/Si) and backward (Si/CuPc) directions increases. The transmitted energy in the backward direction is larger than six times that in the forward direction under a laser beam of 300 mW. The big difference between the transmitted energies was explained in terms of the density of photocarriers injected into the CuPc film and carrier transport characteristics correlated with the degree of disorder of CuPc molecules.
The demand for internal nondestructive testing and inspection techniques is rapidly increasing. Using a continuous wave (CW) terahertz (THz) imaging system, we demonstrate that the internal defects in cross-linked polyethylene (XLPE) plates for power cable insulation can be detected. In a coherent detection scheme based on photomixers, which serve as the THz emitters and receivers, the change of phase occurring with the defects inside the XLPE plates is distinctly measured by the change in the amplitude of the transmitted THz waves. According to the two-dimensional images of THz waves transmitted through the XLPE plates, defects of up to 0.5 mm size located inside the XLPE plates can be detected by the internal nondestructive examination method based on CW–THz waves. This technique will be useful for internal nondestructive testing and inspection of insulation materials that require high resolution in various industries, including the automobiles, electronics, and electrical power industries.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.