Using atmospheric-pressure chemical vapor deposition, we have synthesized vanadium disulfide (VS) flakes with a metallic 1T phase that display nanoscale spiral surface ripples. To understand the origin of these chiral patterns in these transition metal dichalcogenides, tip-enhanced Raman spectroscopy and Kelvin probe force microscopies were jointly used to investigate their crystal structure, possible oxidation, and electronic properties, respectively. We found that the surface corrugation consists of small crystalline domains with distinct orientations. The change in local orientation is observed concomitantly with a spectral shift of the lattice modes of VS and results in the formation of grain boundaries between the domains with distinct orientation. Additionally, the periodic surface structure is modulating the work function of VS by 14 meV.
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http://dx.doi.org/10.1021/acs.jpclett.2c02555 | DOI Listing |
Chem Soc Rev
December 2024
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, School of Electronic Science and Engineering, College of Environment and Ecology, State Key Laboratory of Marine Environmental Science, Department of Physics, iChEM, IKKEM, Xiamen University, Xiamen 361005, China.
Surface-enhanced Raman spectroscopy (SERS) has evolved significantly over fifty years into a powerful analytical technique. This review aims to achieve five main goals. (1) Providing a comprehensive history of SERS's discovery, its experimental and theoretical foundations, its connections to advances in nanoscience and plasmonics, and highlighting collective contributions of key pioneers.
View Article and Find Full Text PDFNanophotonics
March 2024
Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, 72076 Tübingen, Germany.
An analytic model is used to calculate the Raman and fluorescence enhancement of a molecule in between two closely spaced gold nanospheres. Instead of using the conventional approach that only the dipolar plasmonic mode is considered, we calculate the electric field enhancement in the nanometre sized gap, by taking account of the higher order modes in one gold sphere, which couples to the dipolar mode of the other sphere. The experimental confirmation is performed by gap-dependent tip-enhanced Raman spectroscopy (TERS) measurements.
View Article and Find Full Text PDFNanophotonics
March 2024
Department of Physics, Hanyang University, Seoul 04763, Korea.
Transition metal dichalcogenide (TMDs) heterostructure, particularly the lateral heterostructure of two different TMDs, is gaining attention as ultrathin photonic devices based on the charge transfer (CT) excitons generated at the junction. However, the characteristics of the interface of the lateral heterostructure, determining the electronic band structure and alignment at the heterojunction region, have rarely been studied due to the limited spatial resolution of nondestructive analysis systems. In this study, we investigated the confined phonons resulting from the phonon-disorder scattering process involving multiple disorders at the lateral heterostructure interface of MoS-WS to prove the consequences of disorder-mediated deformation in the band structure.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Hefei National Research Center for Physical Sciences at the Microscale and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
Resolving the sequence and structure of flexible biomolecules such as DNA is crucial to understanding their biological mechanisms and functions. Traditional structural biology methods remain challenging for the analysis of small and disordered biomolecules, especially those that are difficult to label or crystallize. Recent development of single-molecule tip-enhanced Raman spectroscopy (TERS) offers a label-free approach to identifying nucleobases in a single DNA chain.
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.
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