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Practical methodology for <i>in situ</i> measurement of micro flow rates using laser diode absorption sensors
摘要： A laser diode-based flowmeter based on the infrared absorption method that can measure in situ micro flow rates from 0.2 to 20 ml h?1 was developed. A 1450 nm laser absorbed in water was irradiated to form a heated spot at 0 mm, and the temperature was measured upstream and downstream of the heated spot. The flow rate was measured by the temperature difference obtained by two diode lasers and photodetectors upstream and downstream of the heated spot. We measured the temperature profile of the flow rate by changing the temperature measurement position and the heating laser energy upstream and downstream of the heated spot, and compared the measurements with the simulation results. As the flow rate increased, the temperature profile shifted downstream, and the measured temperature upstream and downstream were analyzed according to the flow rate. The flow measurement range was adjusted according to the temperature measurement position. Increasing the energy of the heating laser also improved the measurement accuracy in the lower flow range. The developed flowmeter was calibrated by the gravimetric method, and the deviation and measurement uncertainty according to the flow rate were obtained. The maximum measurement uncertainty was 6.8% at a 1 ml h?1 flow rate, and the minimum measurement uncertainty was 1.78% at 8 ml h?1. Thus, it was confirmed that the flow rate can be measured through the temperature difference gauged using a simple diode laser set. Using the laser diode-based flowmeter developed in this study, one can measure the flow rate in situ without injecting contaminants, such as particles, for measurements without cutting the piping. In addition, it can be manufactured in a miniaturized form at a low cost, and thus, it can be used for multi-drug infusion analysis, semiconductor process monitoring, etc.
关键词： near infrared absorption,diode laser,micro flow rate,thermal mass flowmeter
更新于2025-11-25 10:30:42
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Open-path Halon 1301 NDIR sensor with temperature compensation
摘要： Halon 1301 (bromotrifluoromethane) is a kind of fire extinguishing agent in aviation industry. Volume concentration measurement of Halon 1301 is necessary in the design of aircraft fire protection systems. In this research, an open-path Halon 1301 non-dispersive infrared (NDIR) sensor has been developed for in-situ measurement, a novel cavity-type absorption module was designed to get fast response and more compact structure. Experiment results show that measurement was remarkably affected by temperature. Therefore, temperature compensation algorithm was also studied in this thesis, which was proven to be effective within the range of 25 oC-105 oC.
关键词： non-dispersive infrared (NDIR),mid-infrared absorption spectrum,Halon 1301,temperature compensation,concentration measurement
更新于2025-09-23 15:23:52
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Silver nanoparticles with reduced graphene oxide for surface-enhanced vibrational spectroscopy of DNA constituents
摘要： Composite of silver nanoparticles with reduced graphene oxide flakes is proposed for surface enhanced vibrational spectroscopy, particularly for detection of adenine and thymine as constituents of deoxyribonucleic acid. Composite was formed by original method implying simultaneous reduction of silver ions and graphene oxide by discharge plasma at the gas–liquid interface. Combination of nanosized silver with reduced graphene oxide provided greater enhancement of Raman light scattering and infrared light absorption in comparison with separately used components. Addition of the composite to water solutions of adenine and thymine allowed detection of these analytes at micromolar concentrations. Composite of nano-silver with reduced graphene oxide can be prospective for surface enhanced spectroscopy as an alternative to the expensive lithographically prepared noble metal substrates.
关键词： Adenine,Surface Enhanced InfraRed Absorption (SEIRA),Thymine,Reduced graphene oxide,Discharge plasma,Silver nanoparticles,Surface Enhanced Raman Scattering (SERS)
更新于2025-09-23 15:23:52
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The Transitional Transmittance Response of ZIF-8 Gas Adsorption Observed Using Terahertz Waves
摘要： In this study, we recorded the transitional response in terms of terahertz transmittance of zeolitic imidazole framework-8 [Zn(2-methylimidazolate)2, ZIF-8] at 2.0 THz as a function of exposure time to gaseous propane and n-butane. The transmittance at 2.0 THz increased as gas adsorbed onto the ZIF-8. Conversely, during a nitrogen purge, transmittance decreased as the alkane gas desorbed. We estimated time constants for the adsorption and desorption of the two gases by comparing the plots of their responses. We also demonstrated the potential of using a combination of ZIF materials and terahertz technology as a novel gas analyzer.
关键词： Adsorption kinetics,Terahertz vibration,Metal-organic frameworks,Porous solids,Infrared absorption spectroscopy
更新于2025-09-23 15:22:29
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Chemical Identification of Single Ultrafine Particles Using Surface-Enhanced Infrared Absorption
摘要： In the past decade, it has been demonstrated that surface-enhanced infrared absorption (SEIRA) is a powerful method to enhance vibrational signals of thin molecular layers. Much less attention has so far been given to the possibility of using SEIRA for the detection and characterization of nanometer-sized particles, such as ultrafine dust particles. Here, we report on SEIRA measurements demonstrating that even one single particle with a deeply subwavelength dimension of less than 100 nm can be detected and chemically characterized with standard infrared microspectroscopy. Our approach is based on plasmonic resonances of bowtie-shaped Au apertures that are designed to extraordinarily enhance the material-specific phononic excitations of a nanometer-sized silica particle. We show that the bowtie geometry is especially suited for single-particle spectroscopy, as it combines the advantage of an intense electromagnetic hot spot, the size of which can be adjusted to the particle dimension, with easy positioning of ultrafine dust particles inside that hot spot. In agreement with numerical calculations, we show that a detection limit in terms of a particle diameter of less than 20 nm can be achieved, which corresponds to a ratio of the diameter to the vacuum wavelength below 0.002. Our approach offers the possibility of analyzing infrared bands from tiniest particles and thus paves the way toward SEIRA-based devices that can sense ultrafine dust.
关键词： SEIRA,chemical identification,ultrafine particles,plasmonics,bowtie nanoapertures,surface-enhanced infrared absorption
更新于2025-09-23 15:22:29
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Gallium arsenide waveguides as a platform for direct mid-infrared vibrational spectroscopy
摘要： During recent years, mid-infrared (MIR) spectroscopy has matured into a versatile and powerful sensing tool for a wide variety of analytical sensing tasks. Attenuated total reflection (ATR) techniques have gained increased interest due to their potential to perform non-destructive sensing tasks close to real time. In ATR, the essential component is the sampling interface, i.e., the ATR waveguide and its material properties interfacing the sample with the evanescent field ensuring efficient photon-molecule interaction. Gallium arsenide (GaAs) is a versatile alternative material vs. commonly used ATR waveguide materials including but not limited to silicon, zinc selenide, and diamond. GaAs-based internal reflection elements (IREs) are a new generation of semiconductor-based waveguides and are herein used for the first time in direct spectroscopic applications combined with conventional Fourier transform infrared (FT-IR) spectroscopy. Next to the characterization of the ATR waveguide, exemplary surface reactions were monitored, and trace-level analyte detection via signal amplification taking advantage of surface-enhanced infrared absorption (SEIRA) effects was demonstrated. As an example of real-world relevance, the mycotoxin aflatoxin B1 (AFB1) was used as a model analyte in food and feed safety analysis.
关键词： Mid-infrared chem/biosensor,Surface modification,Gallium arsenide,Self-assembled monolayers,Evanescent field absorption,Surface-enhanced infrared absorption
更新于2025-09-23 15:21:01
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Semi-Transparent Organic Solar Cells Enabled by Sequentially Deposited Bilayer Structure
摘要： Semi-transparent organic solar cells (ST-OSCs) have been regarded as a promising candidate for building integrated photovoltaics (BIPV). In general, most of the ST-OSCs are based on bulk heterojunction (BHJ) structure, in which, the morphology of BHJ film must be delicately optimized. In this work, we introduce sequentially deposited bilayer structure into ST-OSCs by using PTB7-Th:IEICO-4F combination. The adoption of bilayer structure not only simplifies the device optimization, it is also found that, as donor and acceptor are separately deposited, the power conversion efficiency (PCE) of bilayer ST-OSCs can be improved by simply increasing the thickness of IEICO-4F, which has strong near infrared absorption but weak visible light absorption, without significantly affecting the average visible light transmittance (AVT) of device. However, in BHJ structure, the increase in BHJ film thickness unavoidably enhances the donor absorption in visible light region, leading to a tradeoff between PCE and AVT in BHJ structure ST-OSCs. Eventually, the bilayer structure device exhibits better overall performance than BHJ structure device, e.g. PCE of 8.5% for bilayer structure vs PCE of 8.1% for BHJ structure with AVT around 21%. Our findings indicate that the sequentially deposited bilayer structure, aside from its easy processing characteristic, also has great potential for preparing high performance ST-OSCs.
关键词： simplified processing,increased infrared absorption,organic solar cells,bilayer structure,semi-transparent
更新于2025-09-23 15:21:01
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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || Surface-Enhanced Infrared Absorption Spectroscopy
摘要： It has been well established that infrared (IR) spectroscopy is a very useful tool for the investigation of gas–solid interfaces, which provides molecular and geometrical information of adsorbed species. Such information obtained for electrode–electrolyte interfaces would be invaluable for understanding electrochemical processes. However, to record IR signals of species in the proximity of an electrode surface, a problem concerning strong IR absorption by the solvent, especially very strong absorption by water, has to be overcome. A way to do so is to minimize the path length which the IR beam has to travel through the solution.
关键词： metal film preparation,Surface-Enhanced Infrared Absorption Spectroscopy,electrochemical processes,SEIRAS,IR spectroscopy
更新于2025-09-23 15:21:01
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Detailed Experiment-Theory Comparison of Mid-Infrared Metasurface Perfect Absorbers
摘要： Realisation of a perfect absorber A = 1 with transmittance and reflectance T = R = 0 by a thin metasurface is one of the hot topics in recent nanophotonics prompted by energy harvesting and sensor applications (A + R + T = 1 is the energy conservation). Here we tested the optical properties of over 400 structures of metal–insulator–metal (MIM) metasurfaces for a range of variation in thickness of insulator, diameter of a disc and intra-disc distance both experimentally and numerically. Conditions of a near perfect absorption A > 95% with simultaneously occurring anti-reflection property (R < 5%) was experimentally determined. Differences between the bulk vs. nano-thin film properties at mid-IR of the used materials can be of interest for plasmonic multi-metal alloys and high entropy metals.
关键词： mid infrared absorption,metasurface,perfect absorption
更新于2025-09-23 15:19:57
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With PBDB-T as the Donor, the PCE of Non-Fullerene Organic Solar Cells Based on Small Molecule INTIC Increased by 52.4%
摘要： At present, most high-performance non-fullerene materials are centered on fused rings. With the increase in the number of fused rings, production costs and production difficulties increase. Compared with other non-fullerenes, small molecule INTIC has the advantages of easy synthesis and strong and wide infrared absorption. According to our previous report, the maximum power conversion efficiency (PCE) of an organic solar cell using PTB7-Th:INTIC as the active layer was 7.27%. In this work, other polymers, PTB7, PBDB-T and PBDB-T-2F, as the donor materials, with INTIC as the acceptor, are selected to fabricate cells with the same structure to optimize their photovoltaic performance. The experimental results show that the optimal PCE of PBDB-T:INTIC based organic solar cells is 11.08%, which, thanks to the open voltage (VOC) increases from 0.80 V to 0.84 V, the short circuit current (JSC) increases from 15.32 mA/cm2 to 19.42 mA/cm2 and the fill factor (FF) increases from 60.08% to 67.89%, then a 52.4% improvement in PCE is the result, compared with the devices based on PTB7-Th:INTIC. This is because the PBDB-T:INTIC system has better carrier dissociation and extraction, carrier transportation and higher carrier mobility.
关键词： polymer solar cells (PSCs),synthesize easily,carrier transportation and extraction,carrier mobility,strong and wide infrared absorption,non-fullerene small molecule acceptor
更新于2025-09-23 15:19:57