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Improvement of Sensing Performance of Impedancemetric C2H2 Sensor Using SmFeO3 Thin-Films Prepared by a Polymer Precursor Method
摘要： A sensitive an impedancemetric acetylene (C2H2) gas sensor device could be fabricated by using perovskite-type SmFeO3 thin-film as a sensor material. The uniform SmFeO3 thin-films were prepared by spin-coating and focusing on the effects of polymer precursor solutions. The prepared precursors and thin-films were characterized by means of thermal analysis, Fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction analysis, scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that particle growth and increase in homogeneity of the prepared thin-film could be accelerated by the addition of acetyl acetone (AcAc) as a coordination agent in the polymer precursor solution. Moreover, the highly crystallized thin-film-based sensor showed good response properties and stabilities to a low C2H2 concentration between 0.5 and 2.0 ppm.
关键词： polymer precursor,acetyl acetone,thin-film,gas sensor,acetylene,perovskite-type oxide,AC impedance
更新于2025-11-14 15:15:56
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Facile Synthesis and Self-assembly of Zinc (2-Diethoxy-phosphorylethynyl)porphyrins
摘要： The synthesis of zinc (2-diethoxyphosphorylethynyl)porphyrins and their self-organization in solid state and in solution are reported. Copper-cocatalyzed Sonogashira reaction of bromoporphyrins with diethyl ethynylphosphonate was used to prepare meso-substituted derivatives Zn4 and Zn5 bearing one or two ethynylphosphonate substituents at the macrocycle. In contrast, copper-free Sonogashira coupling of 2-bromoporphyrin with diethyl ethynylphosphonate is more convenient to prepare porphyrin Zn6 bearing this substituent at the b-pyrrolic position of the macrocycle. The structure of complexes Zn4a.C7H8, Zn4a.CHCl3, Zn4c and Zn5b.CH2Cl2 in crystals were elucidated by X-ray diffraction analysis. The supramolecular self-assembly through weak coordinative binding of the phosphoryl group of one porphyrin molecule to the zinc(II) ion located in the center of another macrocyclic cavity is observed in all crystals. However, Zn(II)-porphyrinates Zn4a and Zn5b exist in the solid state as mutually coordinated dimers while complex Zn4c displays a 1D polymer structure. In all dimer complexes, neighboring porphyrin rings are spatially separated, with Zn–O and P=O bond distances being similar, while the interplanar porphyrin distance is variable to depend on weak intermolecular interactions in the crystals. The self-organization of (phosphorylethynyl)porphyrins is also observed in weakly polar chloroform and detectable by NMR and UV-vis spectroscopies. The mutually coordinated dimer of electron-deficient porphyrin Zn5b was observed in 5.x.10-3 M chloroform solution even at room temperature. Kinetic lability of this supramolecular complex was proven by NMR spectroscopy. The associates of more electron-donating porphyrins Zn4a and Zn4c are less stable and self-assembled dimers become the predominant species in 5.x.10-3 M chloroform solution only below 225 K. The self-assembly of porphyrin Zn4a and Zn5b in more diluted solutions (up to 10-6 M) was also investigated by UV-vis spectroscopy.
关键词： self-organization,phosphonate,porphyrin,catalysis,acetylene linker
更新于2025-09-23 15:23:52
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Influence of C2H2 Flows on Microstructure and Corrosion Resistance of TiCN Films Doped with Carbon Atoms
摘要： Nanosized TiCN/TiN films were deposited on AZ31 by reactive magnetron sputtering under different acetylene flows. The microstructures of obtained films were characterized, and their corrosion behaviors were also investigated. The films doped with carbon atoms under different acetylene flows own different structures and grain sizes. The grain size decreased to some extent, and the film structure changed from polycrystalline to nanocrystalline, with an increase of C2H2 flow. The surface morphology also changed from rough to smooth, with an increase of C2H2 flow. The Tafel curves and electrochemical impedance spectroscopy (EIS) demonstrated that the composite films could greatly improve the corrosion resistance of bare substrates in a 3.5% NaCl solution, and the films' corrosion resistance is different, owing to their different structures and grain sizes.
关键词： acetylene flows,ceramic coatings,microstructure,vacuum,corrosion behavior
更新于2025-09-23 15:22:29
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Synthesis and mesomorphic properties of 4,4”-dialkynyl-2’,3’-difluoro-p-terphenyls – the influence of C≡C acetylene linking bridge
摘要： Dielectrically negative liquid crystals (LC) based on the terphenyl molecular core are widely used class of rod-like mesogenes. One of the most important parameters from applications point of view is optical anisotropy at nematic phase. Hence some applications require high values of birefringence (optical anisotropy in the case of nematic medium), which can be ensured by mesomorphic molecules having high anisotropy of electronic polarisabilities Δα. The molecular design of presented terphenyls is based on the idea of elongation of conjugated π electronic system by terminal acetylene bridge (C ≡ C), as a linking element to terminal alkyl chains. In this work, we developed synthesis of 4,4’’-dialkynyl-2’,3’-difluoroterphenyls with different length of terminal alkyl chains. All synthesised compounds have wide nematic phase ranges. Synthetic problems of this work will be presented. The purity and structures of the final products and intermediates were confirmed by spectral methods: gas chromatography GC-MS, GC-FID, IR spectroscopy and nuclear magnetic resonance NMR. The phase transition temperatures, phase situation and enthalpy data were determined by polarising optical microscopy (POM) and differential scanning calorimetry.
关键词： Terphenyl,acetylene bridge,nematic
更新于2025-09-23 15:21:21
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High-resolution cw-cavity ring-down spectroscopy of allowed (??4??+????5)0 and forbidden (??4??+????5)2 bands of C2H2 using external-cavity quantum cascade laser
摘要： In this paper, we measured the absolute line intensities and air broadening coefficients of several rotationally resolved lines in the P and R branches of the allowed (ν4+ν5)0 and forbidden (ν4+ν5)2 vibrational combinational bands of C2H2 at room temperature 296K. These measurements were performed using an external-cavity quantum cascade laser (EC-QCL) operating at 7.5 μm coupled with high-sensitive cavity ring-down spectroscopy (CRDS). Rotational level-dependent pressure-broadening coefficients of the resolved spectral lines of the selected transitions from (ν4+ν5)0 band are reported here. The air broadening coefficients for 5 rotational lines from P-branch of (ν4+ν5)2 band were also obtained first time with better than 3% uncertainty. The vibrational transition dipole moment squared values of the rotational lines and empirical Herman-Wallis coefficients were also quantified from experimental data. Finally, experimentally obtained all spectroscopic parameters were rigorously compared with previous studies. The new experimental data including several spectroscopic parameters will be useful for atmospheric and astrophysics applications.
关键词： Cavity ring-down spectroscopy,Absolute measurement of line intensities and air broadening coefficients,Transition dipole moment,Ro-vibrational allowed and forbidden transition,Quantum cascade laser,Infrared spectra of Acetylene
更新于2025-09-23 15:21:01
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Photoacoustic spectroscopy telemetry of airport dangerous goods
摘要： A novel photoacoustic spectroscopy telemetry method of detecting trace acetylene gas using a quartz tuning fork is reported. A 1532-nm CW-DFB, fiber-coupled diode laser with power of 12 mW was used as the excitation source while an astronomical telescope was used to collect laser light scattered on the surface of the detected object at a distance of 6 m and the photoacoustic spectroscopy of acetylene was performed. The detection results are consistent with the standard near-infrared absorption coefficient of acetylene. This study provides a new direction for research in photoacoustic spectroscopy telemetry. Future work will quantitatively analyze acetylene gas.
关键词： Photoacoustic spectroscopy,telemetry,acetylene,dangerous goods.
更新于2025-09-19 17:15:36
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Doping effects of ZnO quantum dots on the sensitive and selective detection of acetylene for dissolved-gas analysis applications of transformer oil
摘要： We report on the doping effect on the sensing properties of ZnO quantum dots (QDs) for the detection of acetylene. We found that In-doped ZnO (IZO) QDs exhibited a better sensing performance to 10 ppm acetylene than undoped ZnO (ZO) QDs and Al-doped ZnO (AZO) QDs. The higher sensing response of IZO QDs can be attributed to a greater number of reactive sites for detecting acetylene, which is likely to originate from the increased number of oxygen vacancies, and the larger optical band gap and surface area of IZO. This is due to a higher valence dopant and a smaller particle size. The sensing properties of IZO QDs to 10 ppm acetylene was also found to be superior to previously reported acetylene sensors that are based on semiconducting metal oxides. Furthermore, we demonstrated that 10 ppm of acetylene can be selectively detected in air within ～100 s using a recently developed miniaturized gas chromatography (GC) integrated with the IZO QDs sensor. In addition, we found that the device can detect the major fault gases of hydrogen and acetylene separately within ～100 s. Our study demonstrates that the device can be utilized in the GC-based on-line dissolved gas analysis to detect small amounts of acetylene gas in transformer oil.
关键词： Acetylene gas sensor,Dissolved gas analysis,Gas chromatography,Transformer oil,Quantum dots,ZnO
更新于2025-09-16 10:30:52
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Near-Infrared Tunable Laser Absorption Spectroscopic Acetylene Sensor System Using a Novel Three Mirror-Based, Dense Pattern Gas Cell
摘要： By contrast with the widely reported traditional two mirror‐based Herriott cell, a three mirror‐based dense pattern gas cell was proposed, of which the modeling and design were proven to be effective through a comparison between the simulated spot pattern and effective path length and those of the experimental results. A mechanical structure was designed to adjust the position/angle of the three mirrors for aligning the optical path. The experimentally measured reflection number was 60, resulting in an optical path length of ~11 m, which agrees well with the theoretical value of 10.95 m. Combined with a near‐infrared laser with a center wavenumber located at an acetylene (C2H2) absorption line of 6521.2 cm?1, a C2H2 sensor system was established to verify the feasibility of the three mirror‐based gas cell. Assisted by a data acquisition (DAQ) card, a LabVIEW platform was developed to generate the drive signal of the laser and acquire the second harmonic (2f) signal from the output of the detector. Through Allan variance analysis, the limit of detection (LoD) of the sensor system is 4.36 ppm at an average time of 0.5 s; as the average time exceeds 10 s, the LoD is <1 ppm. The proposed model and design of the three mirror‐based gas cell can be used to realize similar gas cells with different absorption path lengths for gas detection based on infrared absorption spectroscopy.
关键词： laser absorption spectroscopy,multipass gas cell,acetylene detection,wavelength modulation spectroscopy
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Dual-Comb Spectroscopy of Acetylene with a Single, Free-Running MIXSEL Generating two Frequency Combs
摘要： Dual-comb spectroscopy combines the advantages of conventional Fourier transform infrared spectroscopy (FTIR) with the measurement speed, stability and accuracy of multiheterodyne beat note detection. Two optical frequency combs (OFCs) with slightly different line spacing beat on a photodetector and convert the optical spectra down to the more accessible radio frequency (RF) domain. This enables an accurate broadband spectrometer without moving parts featuring short measurement time, however, it also requires two mutually locked OFCs with good noise performance which is challenging. Dual-comb modelocked optically pumped semiconductor disk lasers (SDLs) provide a great simplification. The modelocked integrated external-cavity surface emitting laser (MIXSEL) is a special type of ultrafast SDLs which integrates a semiconductor gain and a saturable absorber in a single epitaxial structure and allows for modelocking in a simple and straight cavity. Most recently we increased the modelocked optical bandwidth above 10 nm with pulse durations below 150 fs. With two intracavity birefringent crystals, the initially unpolarized beam is separated onto two spots on the MIXSEL chip, which can be individually pumped. The dual-comb MIXSEL is a straight linear cavity formed by the two end mirrors (i.e. MIXSEL chip and output coupler (OC) and emits two orthogonally polarized OFCs with a slight difference in line spacing from the same cavity with an intrinsically high mutual coherence. Here, we present dual-comb spectroscopy of acetylene with a single, free-running dual-comb MIXSEL at 1030 nm (290 THz). The laser provides more than 10 nm of optical bandwidth usable for spectroscopic interrogations and with a resolution of 2.73 GHz, we can clearly resolve the individual absorption lines with great precision. Without active stabilization and locking electronics, the overlay of the experimentally acquired dual-comb transmission follows line-by-line the characteristic acetylene transmission envelope as computed from the HITRAN 2016 database after an a posteriori wavelength calibration. Furthermore, the residuals between the observed traces and the HITRAN reference spectrum and its standard deviation of 0.028 attests good transmission intensity precision to our dual-comb spectrometer.
关键词： optical frequency combs,MIXSEL,acetylene,Dual-comb spectroscopy,HITRAN database
更新于2025-09-12 10:27:22
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Hierarchical heterostructures of nanosheet-assembled NiO-modified ZnO microflowers for high performance acetylene detection
摘要： It is of great signi?cance to monitor internal faults of transformer and ensure its normal and safe operation. Usually, acetylene (C2H2) is considered as the characteristic gas caused by discharge failure in transformer. Using gas sensor technology to analyze dissolved gases in transformer oil is an important strategy. Recently, metal oxide semiconductor (MOS) heterojunctions with tailored microstructures have been developed to fabricate high quality gas sensors for gas detection. In this paper, hierarchical ?ower-like NiO/ZnO heterostructures assembled with 2D nanosheets have been synthesized by a facile hydrothermal method and calcination process. Noticeably, the introduction of di?erent contents of NiO (3.0 at%, 5.0 at% and 10.0 at%) leads to di?erent assembly manners of the building nanosheets into hierarchical ?ower-like structures, thus a?ecting the gas performances. Given this, a variety of microscopic characterization methods were used to observe and compare the di?erences in the structures and morphologies of the composites. Through the gas sensing test, it was found that the 5.0 at% NiO-modi?ed ZnO based sensor exhibited superior sensing performances to C2H2 compared with that of others. The enhanced properties may be attributed to the formation of p-n heterojunctions as well as high porosity of the nanosheets. This promising approach is versatile for the applications of high-quality gas sensors.
关键词： NiO/ZnO composites,Acetylene,Gas sensor,Hierarchical heterostructure
更新于2025-09-12 10:27:22