Raman sensing is a powerful technique for detecting chemical signatures, especially when combined with optical enhancement techniques such as using substrates containing plasmonic nanostructures. In this work, we successfully demonstrated surface-enhanced Raman spectroscopy (SERS) of two analytes adsorbed onto gold nanosphere metasurfaces with tunable subnanometer gap widths. These metasurfaces, which push the bounds of previously studied SERS nanostructure feature sizes, were fabricated with precise control of the intersphere gap width to within 1 nm for gaps close to and below 1 nm. Analyte Raman spectra were measured for samples for a range of gap widths, and the surface-affected signal enhancement was found to increase with decreasing gap width, as expected and corroborated via electromagnetic field modeling. Interestingly, an enhancement quenching effect was observed below gaps of around 1 nm. We believe this to be one of the few studies of gap-width-dependent SERS for the subnanometer range, and the results suggest the potential of such methods as a probe of subnanometer scale effects at the interface between plasmonic nanostructures. With further study, we believe that tunable sub-nanometer gap metasurfaces could be a useful tool for the study of nonlocal and quantum enhancement-quenching effects. This could aid the development of optimized Raman-based sensors for a variety of applications.
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http://dx.doi.org/10.1021/acsami.2c01335 | DOI Listing |
Angew Chem Int Ed Engl
December 2024
School of Chemistry, Beihang University, Beijing, 100191, China.
Controlled synthesis of one-dimensional materials at atomic-scale dimensions represents a milestone in nanotechnology, offering the potential to maximize atom utilization while enhancing catalytic performance. However, achieving structural stability and durability at such fine scales requires precise control over material structure and local chemical environment. Here, we introduce dimethylamine (DMA) as a small-molecule modifier, in contrast to conventional long-chain surfactants, to interact with surface Pt atoms.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
November 2024
Key Laboratory of Spin Electron and Nanomaterials of Anhui Higher Education Institutes, School of Chemistry and Chemical Engineering, Suzhou University, Suzhou, Anhui 234000, China.
Surface-enhanced Raman scattering (SERS) technology has been widely used in the field of analytical detection owing to its high sensitivity and fingerprint-recognition ability. However, SERS faces challenges in practical applications related to the precise control of the location of hot spots and molecules entering the hot spot regions. In this study, silver nanoparticles (AgNPs) were used to construct a novel AgNP/AgNP structure by assembling two layers of AgNP thin films using a liquid-liquid interface self-assembly method to obtain a large number of interlayer nanogap structures.
View Article and Find Full Text PDFEnhancing local field intensity through light field compression is one of the core issues in surface plasmon-enhanced spectroscopy. The theoretical framework for the nanostructure composed of a tip and a substrate has predominantly relied on classical electromagnetic models, ignoring the electron tunneling effect. In this paper, we investigate the plasmonic near-field characteristics in the sub-nanometer cavity formed by the tip and the substrate using a quantum-corrected model.
View Article and Find Full Text PDFPhys Chem Chem Phys
October 2024
Department of Mathematics, School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Melbourne, Victoria 3122, Australia.
Employing atomistic molecular dynamics simulations, we investigate the ionic conductivity mechanisms in a partially blocked nanopore containing a centrally positioned spherical constriction, exploring the effects of pore diameter, surface charge, and blockage size. Our results show that ionic mobilities are significantly influenced by the polarity of the surface charge and the size of the pore gap. Particularly, we observe ion-specific effects for K and Cl ions based on their size and charge, especially in sub-nanometer pore gaps.
View Article and Find Full Text PDFAdv Mater
December 2024
School of Physics and Technology, Wuhan University, Wuhan, 430072, China.
Plasmonic nanogaps in strongly coupled metal nanostructures can confine light to nanoscale regions, leading to huge electric field enhancement. This unique capability makes plasmonic nanogaps powerful platforms for boosting light-matter interactions, thereby enabling the rapid development of novel phenomena and applications. This review traces the progress of nanogap systems characterized by well-defined morphologies, controllable optical responses, and a focus on achieving extreme performance.
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