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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • electropolymerization
  • polyporphyrin films
  • quartz crystal microbalance method
  • oxygen electroreduction.
应用领域
  • Applied Chemistry
机构单位
  • G.A. Krestov Institute of Solution Chemistry of RAS
  • University Union Nicola Tesla
  • Ivanovo State University of Chemistry and Technology
61 条数据
?? 中文（中国） ▾

  • Pivotal techniques evaluation in QEPAS system for engineering applications

    摘要： Efforts were made in this study to evaluate a series of pivotal techniques in standard quartz tuning fork (QTF) based quartz enhanced photoacoustic spectroscopy (QEPAS) systems for engineering applications. In current QEPAS systems, a scanning ramp combined with high frequency sinusoidal signal is used to drive the light source for photoacoustic excitation, the scanning cycle was optimized for the first time in experiments guaranteeing that photoacoustic energy accumulation finished to achieve the largest photoacoustic signal, and the optimum modulation index was verified by experiments to be ~5 instead of the simulated result 2.2. As an important step for engineering applications, a long-term (~8 months) experiment was also carried out to evaluate the stability of QTF’s property. In addition, several photoacoustic spectrophone configurations were compared in the optimum geometry parameters, dual-tubes on beam was verified in experiments to be the most efficient one compared with half on-beam and off-beam structures in standard QTF based systems, which is consist with the summary of published papers.

    关键词： Modulation index,Scanning cycle,Long-term stability,Quartz enhanced photoacoustic spectroscopy,Photoacoustic spectrophone

    更新于2025-09-09 09:28:46

  • Direct Growth of Graphene on Fused Quartz by Atmospheric Pressure Chemical Vapor Deposition With Acetylene

    摘要： Direct growth of graphene on target substrates is significant for many optoelectronic applications. A direct growth method of graphene on fused quartz by atmospheric pressure chemical vapor deposition with acetylene as carbon source has been proposed. The functions of growth parameters have been studied by Raman spectroscopy, scanning electron microscope and transmission electron microscope. Large area high quality bilayer AB-stacked graphene films can be fabricated continuously on the whole fused quartz surface with optimal parameters. Governed by a surface-assisted catalyzed growth mode, the short of growth time is not enough to cover the surface completely, while longer duration will induce excrescent layers. Meanwhile, the hydrogen kinetics shows a competition between the catalytic effect and etching effect of hydrogen. The former is dominant with the ratio of hydrogen and argon flow rate below 0.33, while the later take over with more hydrogen concentration. To corroborate the application, a centimeter level graphene optical modulator is assembled with the as-grown samples and proved to work well with a maximum modulation depth of ~3.4% at 1000 nm wavelength. This work paves a convenient way for graphene growth directly on fused quartz with acetylene for great potential applications in photoelectric fields.

    关键词： Optoelectronic applications,Fused quartz,Graphene,Atmospheric pressure chemical vapor deposition,Acetylene

    更新于2025-09-09 09:28:46

  • Temperature-Dependent Refractive Index of Quartz at Terahertz Frequencies

    摘要： Characterisation of materials often requires the use of a substrate to support the sample being investigated. For optical characterisation at terahertz frequencies, quartz is commonly used owing to its high transmission and low absorption at these frequencies. Knowledge of the complex refractive index of quartz is required for analysis of time-domain terahertz spectroscopy and optical pump terahertz probe spectroscopy for samples on a quartz substrate. Here, we present the refractive index and extinction coefficient for α-quartz between 0.5 THz and 5.5 THz (17–183 cm?1) taken at 10, 40, 80, 120, 160, 200 and 300 K. Quartz shows excellent transmission and is thus an ideal optical substrate over the THz band, apart from the region 3.9 ± 0.1 THz owing to a spectral feature originating from the lowest energy optical phonon modes. We also present the experimentally measured polariton dispersion of α-quartz over this frequency range.

    关键词： Terahertz,Quartz,Refractive index,Dispersion,Silica,Optical pump terahertz probe OPTPS,Time-domain spectroscopy,Polariton,SiO2

    更新于2025-09-09 09:28:46

  • Experimental Studies in Micromachined AT-Cut Quartz based Differential Vacuum Gauges

    摘要： In this paper, a micromachined differential pressure sensor based on force frequency effect in AT-Cut quartz bulk acoustic wave (BAW) resonators for vacuum measurements is presented. The frequency shift arising from the stresses generated in the quartz due to force application is known as force frequency effect. Pressure is sensed by monitoring the shifts in the thickness shear mode (TSM) resonance frequency of AT-cut quartz resonator due to the application of differential pressure across the micromachined quartz diaphragm. The sensors exhibit a large dynamic range of 1 mTorr – 100 Torr with a resolution of ~1 mTorr (in the medium vacuum regime). A parametric study has also been carried out to study the effect of resonator thickness and diameter on sensitivity. It was found that the sensor’s response to pressure is extremely sensitive to mechanical boundary conditions which results in performance characteristics such as dependence on the direction of the applied pressure and unexpected scaling with the diaphragm radius.

    关键词： quartz pressure sensor,Pressure sensor,force-frequency effect,piezoelectric,bulk acoustic wave (BAW),micromachined quartz diaphragm

    更新于2025-09-04 15:30:14

  • Quartz-enhanced conductance spectroscopy for nanomechanical analysis of polymer wire

    摘要： Quartz-enhanced conductance spectroscopy is developed as an analytical tool to investigate dynamic nanomechanical behaviors of polymer wires, in order to determine the glass transition temperature (Tg). A polymethyl methacrylate (PMMA) microwire with a diameter of 10 lm was bridged across the prongs of a quartz tuning fork (QTF). With the advantage of QTF self-sensing as compared with micro-cantilevers or other resonators, the resonance frequency and Q factor can be directly determined by means of its electrical conductance spectra with respect to the frequency of the external excitation source (dI/dV vs f), and therefore, no optical beam is required. The Tg of the PMMA microwire was determined by the maximum loss modulus of the QTF, calculated from the resonance frequency and the Q factor as a function of temperature. The measured Tg of the PMMA is 103 (cid:2)C with an error of 62 (cid:2)C. Both heating/cooling and physical aging experiments were carried out, demonstrating that the technique is both reversible and reproducible.

    关键词： PMMA,polymer wire,quartz tuning fork,nanomechanical analysis,glass transition temperature,Quartz-enhanced conductance spectroscopy

    更新于2025-09-04 15:30:14

  • Thermal atomic layer deposition of Sn metal using SnCl <sub/>4</sub> and a vapor phase silyl dihydropyrazine reducing agent

    摘要： This work explores a novel, thermal atomic layer deposition (ALD) process to deposit tin metal at a low temperature. The authors employ 1,4-bis(trimethylsilyl)-1,4-dihydropyrazine (DHP) to reduce SnCl4 on silicon substrates. The authors explored a range of temperatures between 130 and 210 °C to determine the ALD window, which was found to be 170–210 °C. The authors show that this process yields a growth rate of ～0.3 ? per cycle at 190 °C. Furthermore, X-ray photoelectron spectroscopy results showed that the ?lm impurities are reduced for depositions within the ALD window. The reaction mechanism was explored using in situ mass spectrometry and in situ quartz crystal microbalance (QCM). Within the ALD temperature window, the QCM results showed a saturated mass gain during the SnCl4 exposure and a net mass loss during the DHP dose. Consistent with the QCM results, in situ mass spectroscopy data indicate that the DHP exposure step removes surface Cl via formation of volatile trimethylsilyl chloride and pyrazine by-products, effectively reducing the oxidation state of surface-bound Sn. This work is the ?rst thermal Sn metal ALD process to be reported in literature and the oxidation/reduction chemistry presented here may be applied to other metal precursors, increasing the applicability of metal ALD use in industry.

    关键词： quartz crystal microbalance,X-ray photoelectron spectroscopy,ALD window,SnCl4,mass spectrometry,tin metal,thermal atomic layer deposition,DHP

    更新于2025-09-04 15:30:14

  • Relationship between C=C double bond conversion and dissolution kinetics in cross-linking-type photoresists for display manufacture, studied by real-time Fourier transform infrared spectroscopy and quartz crystal microbalance methods

    摘要： Photoresists are an indispensable technology used for manufacturing electronic devices such as displays and semiconductors. In this study, we investigated the relationship between C=C double bond conversion and dissolution kinetics in cross-linking-type photoresists used for display manufacture using real-time Fourier transform infrared spectroscopy (FTIR) and quartz crystal microbalance (QCM) methods. To improve photoresist performance, it is important to understand the development mechanism of photoresists. Two kinds of polymers (a polymer with peeling-type dissolution and a polymer with a dissolution type with Case II diffusion) were used. 1,2-Octanedione-1-[4-(phenylthio)-2-(O-benzoyloxime)] and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide were used as photoinitiators. The dissolution was of the peeling type when the polymers were formulated as a typical cross-linking-type photoresist. With increasing conversion ratio of C=C double bonds, the rate of developer intake decreased and the impregnation threshold before the onset of peeling increased and then decreased. It was also found that the dissolution kinetics were affected by the radicals generated upon the decomposition of photoinitiators.

    关键词： C=C double bond conversion,dissolution kinetics,quartz crystal microbalance,Photoresists,real-time Fourier transform infrared spectroscopy

    更新于2025-09-04 15:30:14

  • Molecular Modeling of CO2 and n-Octane in Solubility Process and α-Quartz Nanoslit

    摘要： After primary and secondary oil recovery, CO2-enhanced oil recovery (EOR) has become one of the most mentioned technologies in tertiary oil recovery. Since the oil is confined in an unconventional reservoir, the interfacial properties of CO2 and oil are different from in conventional reservoirs, and play a key role in CO2 EOR. In this study, molecular dynamics simulations are performed to investigate the interfacial properties, such as interfacial tension, minimum miscibility pressure (MMP), and CO2 solubility. The vanishing interfacial tension method is used to get the MMP (~10.8 MPa at 343.15 K) which is in agreement with the reported experimental data, quantitatively. Meanwhile, the diffusion coefficients of CO2 and n-octane under different pressures are calculated to show that the diffusion is mainly improved at the interface. Furthermore, the displacement efficiency and molecular orientation in α-quartz nanoslit under different CO2 injection ratios have been evaluated. After CO2 injection, the adsorbed n-octane molecules are found to be displaced from surface by the injected CO2 and, then, the orientation of n-octane becomes more random, which indicates that and CO2 can enhance the oil recovery and weaken the interaction between n-octane and α-quartz surface. The injection ratio of CO2 to n-octane is around 3:1, which could achieve the optimal displacement efficiency.

    关键词： molecular dynamics simulation,CO2-enhanced oil recovery,minimum miscibility pressure,α-quartz pore,n-octane

    更新于2025-09-04 15:30:14

  • Electrochemical etching of lightweight nanotips for high quality-factor quartz tuning fork force sensor: atomic force microscopy applications

    摘要： Commercially available quartz tuning forks (QTFs) can be transformed into self-sensing and actuating force sensors by micro-assembling a sharp tip on the apex of a tine. Mass of the tip is critical in determining the quality (Q)-factor of the sensor, therefore, fabrication of the lightweight nanotips is a precondition for high Q-factor QTF sensors. The work reports fabrication of very lightweight tungsten nanotips with a two-step electrochemical etching technique which can be used to develop high Q-factor QTF force sensor. First, a tungsten wire with protective coating at one end (1–2 mm) is etched with a trapezoidal waveform to form a lengthy (～2–5 mm) and slender (diameter ～10–40 μm) micro-needle. In the second step, sharp tip apex is fabricated with a direct current etching. High Q-factor (6600–8000) QTF force sensors have been developed with the fabricated nanotips. Atomic force microscope scanning of nano-grating and a triblock copolymer surface validates the scanning performance of the developed sensors.

    关键词： quartz tuning fork,nanotips,atomic force microscopy,force sensor,electrochemical etching

    更新于2025-09-04 15:30:14

  • Enhanced Photoresponsive Graphene oxide-modified g-C3N4 for Disassembly of Amyloid β Fibrils

    摘要： Protein misfolding and abnormal self-assembly lead to the aggregates of oligomer, fibrils, or senior amyloid β plaques, which is associated with the pathogenesis of many neurodegenerative diseases. Progressive cerebral accumulation of amyloid β-protein (Aβ) was widely proposed to explain the cause of Alzheimer's disease, for which one promising direction of preclinical study is to convert the pre-formed β-sheet structure of amyloid β aggregates into innocent structures. However, the conversion is even harder than the modulation of amyloidosis process. Herein, graphene oxide/carbon nitride (GO/g-C3N4) composite was developed as a good photocatalyst for irreversibly disassembling the amyloid β aggregates of Aβ (33-42) under UV. Quartz crystal microbalance, circular dichroism spectrum, atomic force microscopy, fluorescent spectra, and mechanical property analysis were performed to analyze this photo-degradation process from different aspects for fully understanding the mechanism, which may provide an important enlightenment for the relevant research in this field and neurodegenerative disease study.

    关键词： Neurodegenerative disease,Amyloid β disassembly,Quartz crystal microbalance,Atomic force microscopy,Photo-degradation

    更新于2025-09-04 15:30:14