We integrated graphene with asymmetric metal metasurfaces and optimised the geometry dependent photoresponse towards optoelectronic molecular sensor devices. Through careful tuning and characterisation, combining finite-difference time-domain simulations, electron-beam lithography-based nanofabrication, and micro-Fourier transform infrared spectroscopy, we achieved precise control over the mid-infrared peak response wavelengths, transmittance, and reflectance. Our methods enabled simple, reproducible and targeted mid-infrared molecular sensing over a wide range of geometrical parameters. With ultimate minimization potential down to atomic thicknesses and a diverse range of complimentary nanomaterial combinations, we anticipate a high impact potential of these technologies for environmental monitoring, threat detection, and point of care diagnostics.
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http://dx.doi.org/10.3390/nano13142113 | DOI Listing |
Anal Chem
January 2025
Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China.
Detection of trace gases, such as radioactive carbon dioxide, clumped isotopes, and reactive radicals, is of great interest and poses significant challenges in various fields. Achieving both high selectivity and high sensitivity is essential in this context. We present a highly selective molecular spectroscopy method based on comb-locked, mid-infrared, cavity-enhanced, two-photon absorption.
View Article and Find Full Text PDFACS Omega
December 2024
VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, Espoo, FI-02044, VTT, Finland.
Radiocarbon analysis of nuclear waste produced in nuclear facilities lacks fast, in situ detection methods. Moreover, the amount of radiocarbon desorbing from graphitic waste is not well known. In this study, we demonstrate the use of mid-infrared cavity ring-down spectroscopy combined with an automatic sample processing unit as a method to examine radiocarbon concentration in three types of nuclear waste: spent ion-exchange resin, graphite, and graphite outgassing in sealed storage crates.
View Article and Find Full Text PDFEnviron Sci Technol
December 2024
Institute of Earth Surface Dynamics, University of Lausanne, Lausanne 1015 CH, Switzerland.
Interactions among microbes, minerals, and organic matter are key controls on carbon, nutrient, and contaminant dynamics in soils and sediments. However, probing these interactions at relevant scales and through time remains an analytical challenge due to both their complex nature and the need for tools permitting nondestructive and real-time analysis at sufficient spatial resolution. Here, we demonstrate the ability and provide analytical recommendations for the submicron-scale characterization of complex mineral-organic microstructures using optical photothermal infrared (O-PTIR) microscopy.
View Article and Find Full Text PDFAppl Spectrosc
December 2024
Research Division of Environmental Analytics, Process Analytics and Sensors, Institute of Chemical Technologies and Analytics, TU Wien, Vienna, Austria.
Volatile organic compounds (VOCs) are an ever-growing hazard for health and environment due to their increased emissions and accumulation in the air. Quantum cascade laser-based infrared (QCL-IR) sensors hold significant promise for gas monitoring, thanks to their compact, rugged design, high laser intensity, and high molecule-specific detection capabilities within the mid-infrared spectrum's fingerprint region. In this work, tunable external cavity QCLs were complemented by an innovative germanium-on-silicon integrated optics waveguide sensing platform with integrated microlenses for efficient backside optical interfacing for the tunable laser spectrometer.
View Article and Find Full Text PDFAppl Spectrosc
December 2024
Department of Electrical and Photonics Engineering, Technical University of Denmark, Kongens Lyngby, Denmark.
Combining near-infrared (NIR) and mid-infrared (MIR) spectroscopy to cover both the fundamental and overtone combination molecular vibrational resonances allows more robust analytical methods to be used, such as two-dimensional correlation spectroscopy. However, due to the strong differences in molar absorption coefficients and transparency of the optical material, it is inherently difficult to perform NIR and MIR spectroscopy on aqueous samples using a single instrument. Combining spectra from different instruments and sample presentations can result in unwanted spectral variations, which can influence the prediction models and mitigate the advantages of the combination approaches.
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