The Experts below are selected from a list of 8835 Experts worldwide ranked by ideXlab platform
Zheng Ouyang - One of the best experts on this subject based on the ideXlab platform.
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design of portable mass spectrometers with handheld probes aspects of the sampling and miniature Pumping systems
Journal of the American Society for Mass Spectrometry, 2015Co-Authors: Chienhsun Chen, Tsungchi Chen, Robert Klineschoder, Paul Sorensen, Xiaoyu Zhou, Graham Robert Cooks, Zheng OuyangAbstract:Miniature mass spectrometry analytical systems of backpack configuration fitted with sampling probes could potentially be of significant interest for in-field, real-time chemical analysis. In this study, various configurations were explored in which a long narrow tube was used to connect the turbo and backing pumps used to create and maintain vacuum. Also, for the first time we introduced two new types of pumps for miniature mass spectrometers, the Creare 130 g drag pump and Creare 350 g scroll backing pump. These pumps, along with another Creare 550 turbo pump and the commercially available Pfeiffer HiPace 10 turbo and KnF diaphragm backing pumps, were tested with the backpack configurations. The system performance, especially the scan time, was characterized when used with a discontinuous atmospheric pressure interface (DAPI) for ion introduction. The Pumping performance in the pressure region above 1 mtorr is critical for DAPI operation. The 550 g turbo pump was shown to have a relatively higher Pumping Speed above 1 mtorr and gave a scan time of 300 ms, almost half the value obtained with the larger, heavier HiPace 10 often used with miniature mass spectrometers. The 350 g scroll pump was also found to be an improvement over the diaphragm pumps generally used as backing pumps. With a coaxial low temperature plasma ion source, direct analysis of low volatility compounds glass slides was demonstrated, including 1 ng DNP (2,4-Dinitrophenol) and 10 ng TNT (2,4,6-trinitrotoluene) with Creare 550 g turbo pump as well as 10 ng cocaine and 20 ng DNP with Creare 130 g drag pump.
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breaking the Pumping Speed barrier in mass spectrometry discontinuous atmospheric pressure interface
Analytical Chemistry, 2008Co-Authors: Liang Gao, Graham R Cooks, Zheng OuyangAbstract:The performance of mass spectrometers with limited Pumping capacity is shown to be improved through use of a discontinuous atmospheric pressure interface (DAPI). A proof-of-concept DAPI interface was designed and characterized using a miniature rectilinear ion trap mass spectrometer. The interface consists of a simple capillary directly connecting the atmospheric pressure ion source to the vacuum mass analyzer region; it has no ion optical elements and no differential Pumping stages. Gases carrying ionized analytes were pulsed into the mass analyzer for short periods at high flow rates rather than being continuously introduced at lower flow rates; this procedure maximized ion transfer. The use of DAPI provides a simple solution to the problem of coupling an atmospheric pressure ionization source to a miniature instrument with limited Pumping capacity. Data were recorded using various atmospheric pressure ionization sources, including electrospray ionization (ESI), nano-ESI, atmospheric pressure chemical ionization (APCI), and desorption electrospray ionization (DESI) sources. The interface was opened briefly for ion introduction during each scan. With the use of the 18 W Pumping system of the Mini 10, limits of detection in the low part-per-billion levels were achieved and unit resolution mass spectra were recorded.
Tokihiko Kobata - One of the best experts on this subject based on the ideXlab platform.
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in situ calibration method for ionization gauges and quadrupole mass spectrometers by combining the standard conductance element and the conductance modulation method sce cm method
Vacuum, 2014Co-Authors: Hajime Yoshida, Kenta Arai, Tokihiko KobataAbstract:Abstract A simple method to generate a standard partial pressure p s by using various gas species has been developed for in-situ calibration of IGs and QMSs. Generating p s requires both introducing a test gas with known flow rate Q and estimating the effective Pumping Speed S of the high vacuum pump. The former is realized by introducing a test gas through a standard conductance element (SCE) with a molecular flow condition up to the upstream pressure of 10 4 Pa. The latter is measured by the conductance modulation (CM) method using a gate valve with an orifice. Combination of these two techniques, namely SCE–CM method, enables us to generate p s at the pressure of lower than 10 −2 Pa typically for various gas species. Four hot cathode ionization gauges, a spinning rotor gauge (SRG), and two quadrupole mass spectrometers are calibrated by SCE–CM method using 15 gases (H 2 , He, CH 4 , H 2 O, Ne, CO, N 2 , C 2 H 4 , C 2 H 6 , O 2 , Ar, C 3 H 6 , CO 2 , N 2 O, and C 3 H 8 ) from 10 −6 Pa to 10 −2 Pa. The obtained results are consistent with those of previous studies.
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in situ calibration method for ionization gauges and quadrupole mass spectrometers by combining the standard conductance element and the conductance modulation method sce cm method
Vacuum, 2014Co-Authors: Hajime Yoshida, Kenta Arai, Tokihiko KobataAbstract:Abstract A simple method to generate a standard partial pressure p s by using various gas species has been developed for in-situ calibration of IGs and QMSs. Generating p s requires both introducing a test gas with known flow rate Q and estimating the effective Pumping Speed S of the high vacuum pump. The former is realized by introducing a test gas through a standard conductance element (SCE) with a molecular flow condition up to the upstream pressure of 10 4 Pa. The latter is measured by the conductance modulation (CM) method using a gate valve with an orifice. Combination of these two techniques, namely SCE–CM method, enables us to generate p s at the pressure of lower than 10 −2 Pa typically for various gas species. Four hot cathode ionization gauges, a spinning rotor gauge (SRG), and two quadrupole mass spectrometers are calibrated by SCE–CM method using 15 gases (H 2 , He, CH 4 , H 2 O, Ne, CO, N 2 , C 2 H 4 , C 2 H 6 , O 2 , Ar, C 3 H 6 , CO 2 , N 2 O, and C 3 H 8 ) from 10 −6 Pa to 10 −2 Pa. The obtained results are consistent with those of previous studies.
Endo A. - One of the best experts on this subject based on the ideXlab platform.
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Reactive Magnetron Sputter Deposition of Superconducting Niobium Titanium Nitride Thin Films with Different Target Sizes
'Institute of Electrical and Electronics Engineers (IEEE)', 2017Co-Authors: Bos, Boy Gustaaf Cornelis, Haalebos E. A. F., Gimbel P. M. L., Thoen David, Klapwijk T.m., Baselmans J.j.a., Endo A.Abstract:The superconducting critical temperature (T-\mathrm{c} > 15 K) of niobium titanium nitride (NbTiN) thin films allows for low-loss circuits up to 1.1 THz, enabling on-chip spectroscopy and multipixel imaging with advanced detectors. The drive for large-scale detector microchips is demanding NbTiN films with uniform properties over an increasingly larger area. This paper provides an experimental comparison between two reactive dc sputter systems with different target sizes: A small target (o100 mm) and a large target (127 mm × 444.5 mm). This paper focuses on maximizing the T-\mathrm{c} of the films and the accompanying I-V characteristics of the sputter plasma, and we find that both systems are capable of depositing films with T-\mathrm{c} > 15 K. The resulting film uniformity is presented in a second manuscript in this volume. We find that these films are deposited within the transition from metallic to compound sputtering, at the point where target nitridation most strongly depends on nitrogen flow. Key in the deposition optimization is to increase the system's Pumping Speed and gas flows to counteract the hysteretic effects induced by the target size. Using the I-V characteristics as a guide proves to be an effective way to optimize a reactive sputter system, for it can show whether the optimal deposition regime is hysteresis-free and accessible.Accepted Author ManuscriptTera-Hertz SensingQN/van der Zant LabQN/Klapwijk LabQN/Quantum Nanoscienc
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Reactive magnetron sputter deposition of superconducting niobium titanium nitride thin films with different target sizes
'Institute of Electrical and Electronics Engineers (IEEE)', 2016Co-Authors: Bos B. G. C., Thoen D. J., Haalebos E. A. F., Gimbel P. M. L., Klapwijk T. M., Baselmans J. J. A., Endo A.Abstract:The superconducting critical temperature (Tc > 15K) of niobium titanium nitride (NbTiN) thin films allows for low-loss circuits up to 1.1 THz, enabling on-chip spectroscopy and multi-pixel imaging with advanced detectors. The drive for large scale detector microchips is demanding NbTiN films with uniform properties over an increasingly larger area. This article provides an experimental comparison between two reactive d.c. sputter systems with different target sizes: a small target (100mm diameter) and a large target (127 mm x 444.5 mm). This article focuses on maximizing the Tc of the films and the accompanying I-V characteristics of the sputter plasma, and we find that both systems are capable of depositing films with Tc > 15 K. The resulting film uniformity is presented in a second manuscript in this volume. We find that these films are deposited within the transition from metallic to compound sputtering, at the point where target nitridation most strongly depends on nitrogen flow. Key in the deposition optimization is to increase the system's Pumping Speed and gas flows to counteract the hysteretic effects induced by the target size. Using the I-V characteristics as a guide proves to be an effective way to optimize a reactive sputter system, for it can show whether the optimal deposition regime is hysteresis-free and accessible.Comment: Accepted 2016 November 12, for publication in IEEE Transactions on Applied Superconductivity, Applied Superconductor Conference 2016. 5 pages, 4 figure
Akira Endo - One of the best experts on this subject based on the ideXlab platform.
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Reactive Magnetron Sputter Deposition of Superconducting Niobium Titanium Nitride Thin Films With Different Target Sizes
IEEE Transactions on Applied Superconductivity, 2017Co-Authors: David Johannes Thoen, E. A. F. Haalebos, P. M. L. Gimbel, T. M. Klapwijk, Johannes Jacobus Matheus Baselmans, Akira EndoAbstract:The superconducting critical temperature (Tc > 15 K) of niobium titanium nitride (NbTiN) thin films allows for low-loss circuits up to 1.1 THz, enabling on-chip spectroscopy and multipixel imaging with advanced detectors. The drive for large-scale detector microchips is demanding NbTiN films with uniform properties over an increasingly larger area. This paper provides an experimental comparison between two reactive dc sputter systems with different target sizes: a small target (ø100 mm) and a large target (127 mm × 444.5 mm). This paper focuses on maximizing the Tc of the films and the accompanying I-V characteristics of the sputter plasma, and we find that both systems are capable of depositing films with Tc > 15 K. The resulting film uniformity is presented in a second manuscript in this volume. We find that these films are deposited within the transition from metallic to compound sputtering, at the point where target nitridation most strongly depends on nitrogen flow. Key in the deposition optimization is to increase the system's Pumping Speed and gas flows to counteract the hysteretic effects induced by the target size. Using the I-V characteristics as a guide proves to be an effective way to optimize a reactive sputter system, for it can show whether the optimal deposition regime is hysteresis-free and accessible.
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reactive magnetron sputter deposition of superconducting niobium titanium nitride thin films with different target sizes
arXiv: Superconductivity, 2016Co-Authors: Boy Gustaaf Cornelis Bos, David Johannes Thoen, E. A. F. Haalebos, P. M. L. Gimbel, T. M. Klapwijk, Johannes Jacobus Matheus Baselmans, Akira EndoAbstract:The superconducting critical temperature (Tc > 15K) of niobium titanium nitride (NbTiN) thin films allows for low-loss circuits up to 1.1 THz, enabling on-chip spectroscopy and multi-pixel imaging with advanced detectors. The drive for large scale detector microchips is demanding NbTiN films with uniform properties over an increasingly larger area. This article provides an experimental comparison between two reactive d.c. sputter systems with different target sizes: a small target (100mm diameter) and a large target (127 mm x 444.5 mm). This article focuses on maximizing the Tc of the films and the accompanying I-V characteristics of the sputter plasma, and we find that both systems are capable of depositing films with Tc > 15 K. The resulting film uniformity is presented in a second manuscript in this volume. We find that these films are deposited within the transition from metallic to compound sputtering, at the point where target nitridation most strongly depends on nitrogen flow. Key in the deposition optimization is to increase the system's Pumping Speed and gas flows to counteract the hysteretic effects induced by the target size. Using the I-V characteristics as a guide proves to be an effective way to optimize a reactive sputter system, for it can show whether the optimal deposition regime is hysteresis-free and accessible.
I Safi - One of the best experts on this subject based on the ideXlab platform.
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recent aspects concerning dc reactive magnetron sputtering of thin films a review
Surface & Coatings Technology, 2000Co-Authors: I SafiAbstract:Abstract In this paper, attention is paid to DC reactive magnetron sputtering and its implications, such as the hysteresis effect and the instability in the reactive gas pressure, differential poisoning of magnetron cathode, as well as the methods which are used to control the process. These methods include: (a) increasing the Pumping Speed, which requires considerable additional costs; (b) increasing the target-to-substrate distance, which requires larger vacuum chambers (hence, higher costs) and also results in lower deposition rates; (c) obstructing reactive gas flow to the cathode with the resultant reduction of deposition rate and the need for complicated arrangements; (d) pulsed reactive gas flow, which requires an extensive amount of process optimisation and a continuous monitoring and adjustment of the process parameters; (e) plasma emission monitoring; and (f) voltage control, which are inexpensive and have proved to be powerful techniques for monitoring and controlling the reactive sputtering processes, in real time without disturbing the discharge, for the deposition of high-quality films, reproducibly. In addition, arcing and methods to avoid it are reviewed; this includes, arc initiations and their destructive effects (e.g. driving the process to become unstable, reducing the target lifetime and creating defects in the sputtered films), time required for arcs to occur, and finally, methods of avoiding arcs. The latter includes the use of unipolar or bipolar pulsing techniques at frequencies in the range 10–70 kHz.