This paper investigates the impact of graphene on tip-enhanced Raman spectroscopy (TERS) by developing an electromagnetic characterization of the TERS-graphene device system. The study focuses on the interaction between the tip, the gate voltage, and the sample, specifically examining the electromagnetic effects in the system. Employing a finite element method (FEM)-based simulation model, we meticulously dissect the electric field distribution and the Raman amplification when graphene is introduced into the system. Our findings reveal that including graphene results in a marginal reduction in Raman amplification and a negligible variation in the induced charges within the system. To reinforce our simulations, we employ a simplified capacitor model, which corroborates our results, showcasing negligible induced charges and validating the obtained capacitance values. In this manuscript, we also explore the influence of the setup on the electro-optical properties of graphene, revealing a slight variation in conductivity despite strong changes in chemical potential. Overall, this work contributes to understanding TERS's electromagnetic aspects in the presence of graphene.
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http://dx.doi.org/10.1364/OL.512195 | DOI Listing |
ACS Mater Au
January 2025
Liquid Crystal Research Laboratory, Department of Physics, University of Lucknow, Lucknow, Uttar Pradesh 226007, India.
Polymer-dispersed liquid crystals (PDLCs) stand at the intersection of polymer science and liquid crystal technology, offering a unique blend of optical versatility and mechanical durability. These composite materials are composed of droplets of liquid crystals interspersed in a matrix of polymeric materials, harnessing the optical properties of liquid crystals while benefiting from the structural integrity of polymers. The responsiveness of LCs combined with the mechanical rigidity of polymers make polymer/LC composites-where the polymer network or matrix is used to stabilize and modify the LC phase-extremely important for scientists developing novel adaptive optical devices.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
December 2024
Department of Chemistry, Faculty of Science, Gazi University, Yenimahalle, Ankara 06560, Turkey. Electronic address:
Coumarin compounds have heterocyclic core with different properties such as high quantum yields, broad Stokes shifts, and superior photophysical and biological activity. It is known that fluorescence properties increase with increased intramolecular charge transfer in systems where electron-withdrawing or donor groups are attached to different positions of the coumarin compound. When these compounds interact with analytes in the environment, the analytes in the environment can be detected by quenching or increasing fluorescence.
View Article and Find Full Text PDFACS Nano
January 2025
Consiglio Nazionale delle Ricerche (CNR) - Istituto per la Sintesi Organica e la Fotoreattività (ISOF), via Piero Gobetti 101, 40129 Bologna, Italy.
This study reveals the capability of nanostructured organic materials to undergo pseudomorphic transformations, a ubiquitous phenomenon occurring in the mineral kingdom that involves the replacement of a mineral phase with a new one while retaining the original shape and volume. Specifically, it is demonstrated that the postoxidation process induced by HOF·CHCN on preformed thiophene-based 1D nanostructures preserves their macro/microscopic morphology while remarkably altering their electro-optical properties by forming a new oxygenated phase. Experimental evidence proves that this transformation proceeds via an interface-coupled dissolution-precipitation mechanism, leading to the growth of a porous oxidized shell that varies in thickness with exposure time, enveloping the pristine smooth core.
View Article and Find Full Text PDFMolecules
December 2024
CP2M-ESCPE Lyon, CNRS, University Claude Bernard Lyon 1, UMR 5128, 43 Bd du 11 Nov. 1918, CEDEX, 69616 Villeurbanne, France.
TiO:Eu nanoparticles with varying europium concentrations were successfully synthesized via a one-pot sol-gel approach using a molecular heterometallic single-source precursor (SSP) Eu-Ti. For comparison, nanomaterials with similar europium levels were also produced by impregnating europium salts onto the same TiO substrate. All the nanomaterials were thoroughly characterized using Eu elemental analysis, powder X-ray diffraction (XRD), scanning (SEM), transmission (TEM), scanning transmission electron microscopy (STEM), Brunauer-Emmett-Teller (BET) analysis, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and photoluminescence (PL).
View Article and Find Full Text PDFSmall
December 2024
Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing, 100083, China.
The polymer dispersed liquid crystal (PDLC) holds potential application in smart windows, owing to its feasibility in regulating the transmittance of specific wavelength bands to improve energy utilization. Herein, a composite PDLC smart window is designed, which showcases high emissivity of 93.79% in the mid-infrared region and features the regulation of ultraviolet (UV), visible, and near-infrared (NIR) light.
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