The Experts below are selected from a list of 4299 Experts worldwide ranked by ideXlab platform
Vladimiro Mujica - One of the best experts on this subject based on the ideXlab platform.
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solvent effects on the dynamic polarizability and raman response of molecule Metal Oxide hybrid clusters
ChemPhysChem, 2016Co-Authors: Yoelvis Orozcogonzalez, P Tarakeshwar, Vladimiro Mujica, Sylvio CanutoAbstract:Currently, there is considerable interest in the properties of Semiconducting Metal Oxide nanoparticle substrates because of their utility in surface-enhanced Raman scattering, dye-sensitized solar cells, and photocatalysis. While the enhancement of Raman activities of molecules adsorbed on these nanoparticles is due to a large increase in the polarizability, because of charge transfer from the molecule to the Semiconducting nanoparticle, little is known about the factors responsible for modulating the polarizability, particularly the influence of the solvent. Consequently, we have carried out Monte Carlo simulations of several hybrids to study the solvent effect on the dynamic polarizabilities and electronic spectra. Our results indicate that the presence of the solvent induces a shift and an increase in the polarization response that is dependent on the identity of the hybrid. The observed enhancement can be attributed to both the resonant character of the excitation and the participation of the solvent in the charge redistribution. The methodology employed in this work could be very valuable in both identifying and developing Metal Oxides as novel molecular sensors.
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sers as a probe of charge transfer pathways in hybrid dye molecule Metal Oxide complexes
Journal of Physical Chemistry C, 2014Co-Authors: P Tarakeshwar, Julio L Palma, Daniel Finkelsteinshapiro, A Keller, Ines Urdaneta, Monica Calatayud, O Atabek, Vladimiro MujicaAbstract:Interfacial charge transfer has been an area of intense interest because of its relevance in molecular electronics, dye-sensitized solar cells, surface-enhanced Raman scattering (SERS), and photocatalysis. Although the chemical natures of both the contact and the linker have been shown to play important roles in determining the properties of hybrid dye/molecule–Metal Oxide complexes, little is known about the nature of the charge-transfer pathways. In this work, we explore in detail the idea that Raman enhancement and charge transfer are intimately related. To this end, we analyze the vibrational modes of molecules exhibiting the maximum enhancement of the Raman activities when they are adsorbed on Semiconducting Metal Oxide nanoparticles. Our analysis of the potential energy distributions of these modes in the hybrid complexes indicates the significant involvement of bending and torsional modes of atoms deep within the Metal Oxide nanoparticle. Whereas the individual contribution of each of these Oxide b...
Rui Gao - One of the best experts on this subject based on the ideXlab platform.
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Metal Oxide gas sensors: Sensitivity and influencing factors
Sensors, 2010Co-Authors: Chengxiang Wang, Longwei Yin, Luyuan Zhang, Dong Xiang, Rui GaoAbstract:Conductometric Semiconducting Metal Oxide gas sensors have been widely used and investigated in the detection of gases. Investigations have indicated that the gas sensing process is strongly related to surface reactions, so one of the important parameters of gas sensors, the sensitivity of the Metal Oxide based materials, will change with the factors influencing the surface reactions, such as chemical components, surface-modification and microstructures of sensing layers, temperature and humidity. In this brief review, attention will be focused on changes of sensitivity of conductometric Semiconducting Metal Oxide gas sensors due to the five factors mentioned above.
Brent T Marquis - One of the best experts on this subject based on the ideXlab platform.
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Semiconducting Metal Oxide sensor array for the selective detection of combustion gases
Sensors and Actuators B-chemical, 2003Co-Authors: A A Tomchenko, Brent T Marquis, Gregory P Harmer, John W AllenAbstract:A sensor array consisting of discrete thick-film sensors based on various semiconductor Metal Oxides (SMO) has been designed and fabricated for flue gas analysis purposes. The selection of the sensitive materials for the array has been accomplished as a result of extensive studies of gas-sensitive properties of SMO. The thick-film sensors, prototypes and the array’s components, were fabricated on the basis of commercial sensor platforms. A drop-coating technique was used for Metal Oxide paste deposition followed by in situ drying and annealing of the deposited films in air by platinum heaters integrated into the platforms. We show the results obtained with a variety of thick-film Metal Oxide species and examine their sensitivities at different fixed operating temperatures (200‐400 8C). The feasibility of the electronic system consisted of SnO2, ZnO, WO3, CuO, and In2O3 sensors to discriminate and recognize various gaseous constituents of a combustion gas is demonstrated. Principal component analysis along with several classification schemes were used to identify nitrogen Oxides, ammonia, sulfur diOxide, and other gaseous pollutants. # 2003 Elsevier Science B.V. All rights reserved.
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a Semiconducting Metal Oxide sensor array for the detection of nox and nh3
Sensors and Actuators B-chemical, 2001Co-Authors: Brent T Marquis, J F VetelinoAbstract:Abstract In many fossil fuel burning systems, NOx emissions are minimized by a selective catalytic reduction (SCR) technique where NH3 is injected into the flue gas stream to react with NOx to form environmentally safe gases, such as nitrogen and water vapor. Unfortunately, this process is usually incomplete, resulting in either NOx emissions or excess NH3 (NH3 slip). Therefore, a critical need exits for an in situ sensor array near the stack to provide real-time control of the NH3 injection, and hence, minimize the NOx emissions released into the environment. In the present work, Semiconducting Metal Oxide (SMO) film technology is used to engineer a small, robust, sensitive, and selective sensor array to detect NOx and NH3 emissions. Many thin film tungsten triOxide (WO3) based sensing elements were tested in order to identify two film recipes capable of sensitively and selectively detecting NOx and NH3. The critical parameters inherent in each film recipe are type of substrate material, film thickness, doping, deposition temperature, and operating temperature. The two element sensor array’s response characteristics analyzed include the response and recovery times, rates of reaction, dynamic range, sensitivity, repeatability and selectivity.
Lado Filipovic - One of the best experts on this subject based on the ideXlab platform.
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Improved Sensing Capability of Integrated Semiconducting Metal Oxide Gas Sensor Devices.
Sensors, 2019Co-Authors: Ayoub Lahlalia, Olivier Le Neel, Siegfried Selberherr, Ravi Shankar, Lado FilipovicAbstract:Semiconducting Metal Oxide (SMO) gas sensors were designed, fabricated, and characterized in terms of their sensing capability and the thermo-mechanical behavior of the micro-hotplate. The sensors demonstrate high sensitivity at low concentrations of volatile organic compounds (VOCs) at a low power consumption of 10.5 mW. In addition, the sensors realize fast response and recovery times of 20 s and 2.3 min, respectively. To further improve the baseline stability and sensing response characteristics at low power consumption, a novel sensor is conceived of and proposed. Tantalum aluminum (TaAl) is used as a microheater, whereas Pt-doped SnO2 is used as a thin film sensing layer. Both layers were deposited on top of a porous silicon nitride membrane. In this paper, two designs are characterized by simulations and experimental measurements, and the results are comparatively reported. Simultaneously, the impact of a heat pulsing mode and rubber smartphone cases on the sensing performance of the gas sensor are highlighted.
Wei Huang - One of the best experts on this subject based on the ideXlab platform.
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Metal composition and polyethylenimine doping capacity effects on Semiconducting Metal Oxide polymer blend charge transport
Journal of the American Chemical Society, 2018Co-Authors: Wei Huang, Li Zeng, Ran Li, Binghao Wang, Gang Wang, Xinan Zhang, R P H Chang, Junsheng Yu, Michael J BedzykAbstract:Charge transport and film microstructure evolution are investigated in a series of polyethylenimine (PEI)-doped (0.0–6.0 wt%) amorphous Metal Oxide (MO) semiconductor thin film blends. Here, PEI doping generality is broadened from binary In2O3 to ternary (e.g., In+Zn in IZO, In+Ga in IGO) and quaternary (e.g., In+Zn+Ga in IGZO) systems, demonstrating the universality of this approach for polymer electron doping of MO matrices. Systematic comparison of the effects of various Metal ions on the electronic transport and film microstructure of these blends are investigated by combined thin-film transistor (TFT) response, AFM, XPS, XRD, X-ray reflectivity, and cross-sectional TEM. Morphological analysis reveals that layered MO film microstructures predominate in PEI-In2O3, but become less distinct in IGO and are not detectable in IZO and IGZO. TFT charge transport measurements indicate a general coincidence of a peak in carrier mobility (μpeak) and overall TFT performance at optimal PEI doping concentrations. O...
