Papers by Keyword: NH₃

Abstract: A new measurement system has been introduced to perform real-time measurements of molecular air contaminants at different location in a clean room down to a concentration of approximately 0.1 ppb. The system consists of an air sampling unit coupled to a proton transfer mass spectrometer and a Cavity Ring-Down Spectrometer. The measurements show that the time average concentrations of more than 10 different volatile impurity molecules exceed 1 ppb.

Abstract: Few-layer graphene sheets were synthesis using LPE with ultrasonic-assisted. The pristine graphite is directly exfoliated in deionized water with small addition of NH₃ solution. In this study, we will investigate the relationship between concentration of NH₃ solution corresponds to the graphene yield. The concentration of the NH₃ solution varies from 18% to 26%. NH₃ solution plays an important role as a medium to peel of graphite in the exfoliation process to form few-layer graphene sheets. The structural properties of the few-layer graphene sheets were examined using XRD, Raman Analysis, Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM) followed by UV-Vis Spectroscopy for its optical properties. The finest of few-layer graphene sheets was produced at 26% of NH₃ concentration. This optimization results in a few layers of graphene sheets that may be used in the fields of nanoelectronics and optoelectronics.

Abstract: Gas Exchange Device (GED) was integrated with Inductively Coupled Plasma Mass Spectrometry(ICP-MS) for analysis of metallic particles in NH3 and HCl gases used in semiconductormanufacturing. A single pg/kg (ppq) level of metallic impurities in these gases could be determinedwithout any sample preparation.

Abstract: Functionalized Multi-Walled Carbon Nanotubes (MWCNTs-OH) network with thickness 4μm was made by the vacuum filtration from suspension (FFS) method. The morphology, structure and optical properties of the MWCNTs film were characterized by SEM and UV-Vis. spectra techniques. The SEM images reflected highly ordered network in the form of ropes or bundles with close-packing which looks like spaghetti. The absorbance spectrum revealed that the network has a good absorbance in the UV-Vis. region. The gas sensor system was used to test the MWCNT-OH network to detect NH₃ gas at room temperature. The resistance of the sensor was increased when exposed to the NH₃ gas. The sensitivities of the network were 1.3% at 14ppm, 3.3% at 27ppm and 6.13% at 68ppm. The sensor is specifically sensitive to NH₃ gas and does not affect by the amount of ambient air.

Abstract: For horizontally stacked nanowires or-sheets to compete with finFET, the development of a robust inner spacer module is essential. These inner spacers are required to reduce the parasitic capacitance due to the overlap between the source/drain and gate regions. Here we propose an inner spacer integration scheme for Si gate-all-around (GAA) taking advantage of the selective oxidation and oxide removal of SiGe versus Si. Compared to thermal oxide, we found a very high SiGe-oxide etch rate in aqueous HF solutions. When using an NH₃/NF₃ remote plasma, a reduction in etch rate was found for SiGe-oxide versus thermal oxide. We show Si_0.75Ge_0.25-oxide meets inner spacer requirements for leakage current and electrical breakdown field and finally demonstrate the proposed inner spacer integration scheme using a fin-shaped SiGe/Si multilayer topological-test-structure.

Abstract: Gas/vapor cloud explosions and fires are responsible for most of the largest property loss events worldwide in the hydrocarbon industry. Motivation for this article is to summarize explosion pressure caused by corrosive gases/vapors in terms of mathematical modeling. Presented explosions based on real scenarios of accidents associated with transport and storage facilities with corrosive flammable chemicals. While explosions of pure flammable chemicals are well described in the literature, the information about explosions of corrosive and toxic flammable substances is rather scarce. This work aims at studying the explosion behavior of pure hydrogen-air, pure ammonia-air, ammonia-hydrogen-air, ammonia-methanol-air, ammonia-ethanol-air mixtures at different initial temperatures and pressures. The results of mathematical modeling of the calculated maximum explosion pressure are described.

Abstract: The rapid growth in the use of corrosive gases transported by pressure vessels and pipelines has brought significant increase of risk to a number of people, both workers and public, whose life could be endangered at any one time by accident involving these chemicals. Due to the complexity of the involved physical phenomena and to the lack of an adequate amount of reliable experimental data, a number of different models and calculation procedures for estimating the consequences following the release of a corrosive gas are presently reported in the literature. The contribution deals with real scenarios of accidents associated with stationary risk facilities with corrosive flammable toxic chemicals. The study presents the results of hazardous zone calculation for the event of various corrosive liquids (Cl₂, NH₃, CCl₂O, C₃H₄O) toxic releases. The goal of this article is to present the results of the approach of modeling using the standard methods and to demonstrate the importance of the next development stage in the area of corrosive materials accident modeling of releases and dispersions in cases of accident.

Abstract: Corrosion is typical of the damage that occurs in ageing pressure vessels and pipelines used in industrial processes as a result of reactive products inside or harsh environmental conditions on the outside. Motivation for this article is to summarize cases, causes, consequences, and prevention in terms of models for the prediction of explosion pressure from BLEVEs. The contribution deals with real scenarios of accidents associated with transport and storage pressurized facilities with corrosive flammable chemicals. While the LPG, propane, and butane BLEVEs are well described in the literature, the information about corrosive and toxic flammable substances are rather scarce. The study presents the results of hazardous zone calculation for the event of ammonia corrosive non-flammable chemical releases. For calculations of the BLEVE overpressure, AICHE ́s Prugh ́s and Baker ́s models together with Effects 9.0.8. Rupture of vessels model were used for this study.

Abstract: Polyaniline (PANI) nano-thin films were deposited on a novel microstructure silicon (MSS) substrate via in-situ self-assembly approach for NH₃ gas-sensing. The MSS was prepared by alkaline etching process, and gold interdigital electrodes were formed on the MSS surface by vacuum evaporation. The characterization of the MSS and PANI nanothin film were investigated by scanning electron microscope (SEM) and UV-Vis absorption spectroscopy. SEM images showed that the MSS exhibited an orderly uniform hemisphere array structure, and the MSS surface was covered by a compact PANI thin film which consists of PANI nanoparticles and PANI nanofibers. The gas-sensing properties of the sensor were examined at room temperature. The results revealed that the sensor exhibited a good response and recovery characteristics to NH₃.

Abstract: In this paper, the graphene-polyaniline (PANI) nanocomposite thin film was prepared by the in situ self-assembly method for the ammonia (NH3) gas sensor application, which was characterized by scanning electron microscopy (SEM) and UV-vis spectroscopy. The NH3 sensing performance and mechanism of the nanocomposite film were investigated. The results revealed that the sensor based on graphene-polyaniline nanocomposite film exhibited better sensing properties and restorability than those of single graphene film.