Journal articles: 'Buffer gas trap'

1

Natisin, M. R., J. R. Danielson, and C. M. Surko. "Formation of buffer-gas-trap based positron beams." Physics of Plasmas 22, no. 3 (March 2015): 033501. http://dx.doi.org/10.1063/1.4913354.

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2

Vazquez, Timothy, Colette Taylor, and Theresa Evans-Nguyen. "Ion-Trap-Performance Enhancement Utilizing Pulsed Buffer-Gas Introduction." Analytical Chemistry 90, no. 17 (August 8, 2018): 10600–10606. http://dx.doi.org/10.1021/acs.analchem.8b02881.

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3

Tattersall, W., R. D. White, R. E. Robson, J. P. Sullivan, and S. J. Buckman. "Simulations of pulses in a buffer gas positron trap." Journal of Physics: Conference Series 262 (January 1, 2011): 012057. http://dx.doi.org/10.1088/1742-6596/262/1/012057.

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4

Machacek, J. R., S. J. Buckman, and J. P. Sullivan. "A pulsed positronium beam using a positron buffer gas trap." Review of Scientific Instruments 91, no. 3 (March 1, 2020): 033311. http://dx.doi.org/10.1063/1.5128012.

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5

Doyle, John M., Bretislav Friedrich, Jinha Kim, and David Patterson. "Buffer-gas loading of atoms and molecules into a magnetic trap." Physical Review A 52, no. 4 (October 1, 1995): R2515—R2518. http://dx.doi.org/10.1103/physreva.52.r2515.

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6

Lunney, M. D. N., F. Buchinger, and R. B. Moore. "The Temperature of Buffer-gas Colled Ions in a Paul Trap." Journal of Modern Optics 39, no. 2 (February 1992): 349–60. http://dx.doi.org/10.1080/09500349214550341.

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7

Higaki, Hiroyuki, Koji Michishio, Kaori Hashidate, Akira Ishida, and Nagayasu Oshima. "Accumulation of LINAC based low energy positrons in a buffer gas trap." Applied Physics Express 13, no. 6 (May 28, 2020): 066003. http://dx.doi.org/10.35848/1882-0786/ab939f.

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8

Ma, Ce, Heewon Lee, and David M. Lubman. "Computer Simulation of the Operation of a Three-Dimensional Quadrupole Ion Trap." Applied Spectroscopy 46, no. 12 (December 1992): 1769–79. http://dx.doi.org/10.1366/0003702924123458.

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A computer simulation of the motion of ions in a three-dimensional (3-D) quadrupole ion trap has been performed with a Gateway 386 PC/AT computer. The SIMION program was used as the main program to calculate the potential array of the ion trap space. Several user-written programs were interfaced to the SIMION program to simulate the effects of changing various operating conditions, such as the radio-frequency (rf) potential, the collisional buffer gas, external ion injection, dc ejection from the trap, and resonance ejection. With the use of this simulation, the total storage mass range could be obtained as a function of rf voltage and frequency. The simulations show, as expected, that the collisional buffer gas plays an important role in both stabilizing the trajectory of high-kinetic-energy ions (hot ions) inside the ion trap and trapping ions injected from an external source. Several different buffer gases were studied for their effects upon the trapping motion. In addition, both the total mass ejection that results from applying a dc pulse on the output end-cap electrode and the ion ejection that results from applying an rf frequency to the end cap to produce resonance ejection were also studied with this simulation program. It is demonstrated that a simple PC computer using a modified SIMION program provides results very similar to those expected from theory or from previous work.

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9

Janulyte, Aurika, Yves Zerega, Boris Brkić, Stephen Taylor, and Jacques Andre. "Accurate modelling of small-scale linear ion trap operating mode using He buffer gas to improve sensitivity and resolution for in-the-field mass spectrometry." Journal of Analytical Atomic Spectrometry 34, no. 8 (2019): 1672–82. http://dx.doi.org/10.1039/c9ja00017h.

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10

Lei, She, Wang Wen-Ming, Bai Lei, Sun Huan-Yao, Zhu Xi-Wen, Li Jiao-Mei, and Gao Ke-Lin. "Fluorescence Detection and Buffer Gas Cooling of Trapped Mercury Ions in Paul Trap." Chinese Physics Letters 25, no. 5 (May 2008): 1653–56. http://dx.doi.org/10.1088/0256-307x/25/5/036.

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11

Sugiyama, K., and J. Yoda. "Anharmonic oscillation of ions trapped in a rf trap with light buffer gas." Applied Physics B Photophysics and Laser Chemistry 51, no. 2 (August 1990): 146–52. http://dx.doi.org/10.1007/bf00326016.

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12

Nötzold, Markus, Saba Zia Hassan, Jonas Tauch, Eric Endres, Roland Wester, and Matthias Weidemüller. "Thermometry in a Multipole Ion Trap." Applied Sciences 10, no. 15 (July 30, 2020): 5264. http://dx.doi.org/10.3390/app10155264.

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We present a characterization of the ions’ translational energy distribution in a multipole ion trap. A linear mapping between the energy distribution of the trapped ions onto the ions’ time-of-flight (TOF) to a detector is demonstrated. For low ion temperatures, a deviation from linearity is observed and can be attributed to the emergence of multiple potential minima. The potential landscape of the trapped ions is modeled via the finite element method, also accounting for subtleties such as surface-charge accumulation. We demonstrate the validity of our thermometry method by simulating the energy distribution of the ion ensemble thermalized with buffer gas using a Molecular Dynamics (MD) simulation. A comparison between the energy distribution of trapped ions in different multipole trap configurations—i.e., with hyperbolic rods, cylindrical rods, and cylindrical wires—is provided. With these findings, one can map the temperature of the trapped ions down to the Kelvin regime using their TOF distributions. This enables future studies on sympathetic cooling and chemical reactions involving ions in multipole traps.

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13

Krasnov, I. V. "Bichromatic dark trap immersed in a buffer gas with an admixture of resonant atoms." Laser Physics 30, no. 8 (July 16, 2020): 085501. http://dx.doi.org/10.1088/1555-6611/ab99c7.

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14

Hasse, H. U., St Becker, G. Dietrich, N. Klisch, H. J. Kluge, M. Lindinger, K. Lützenkirchen, L. Schweikhard, and J. Ziegler. "External-ion accumulation in a Penning trap with quadrupole excitation assisted buffer gas cooling." International Journal of Mass Spectrometry and Ion Processes 132, no. 3 (April 1994): 181–91. http://dx.doi.org/10.1016/0168-1176(93)03924-b.

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15

Derevyashkin, S. P., P. V. Borisyuk, K. Yu Khabarova, N. N. Kolachevsky, S. A. Strelkin, E. V. Tkalya, D. O. Tregubov, I. V. Tronin, and V. P. Yakovlev. "Cumulative loading of the ion trap by laser ablation of thorium target in buffer gas." Laser Physics Letters 18, no. 1 (December 14, 2020): 015501. http://dx.doi.org/10.1088/1612-202x/abcf28.

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16

Alili, A., J. André, and F. Vedel. "Buffer Gas Cooling of Ions Stored in an R.F. Trap: Computed Properties of the Ionic Cloud." Physica Scripta T22 (January 1, 1988): 325–28. http://dx.doi.org/10.1088/0031-8949/1988/t22/054.

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17

Yoda, Jun, and Kazuhiko Sugiyama. "Determination of Characteristics of Yb+Ion Cloud Trapped in a RF Trap with He Buffer Gas." Japanese Journal of Applied Physics 31, Part 1, No. 11 (November 15, 1992): 3750–53. http://dx.doi.org/10.1143/jjap.31.3750.

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18

deCarvalho, R., N. Brahms, B. Newman, J. M. Doyle, D. Kleppner, and T. Greytak. "A new path to ultracold hydrogen." Canadian Journal of Physics 83, no. 4 (April 1, 2005): 293–300. http://dx.doi.org/10.1139/p05-013.

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Ultracold hydrogen offers unique possibilities for precision spectroscopy, studies of atomic interactions, and the creation of quantum fluids containing mixtures of hydrogen and deuterium. Current techniques for trapping and cooling hydrogen have produced large condensates with N ∼ 109 atoms, but suffer from a variety of experimental limitations. Among these are the slow evaporative cooling rate due to the small HH elastic-scattering cross section, the need for a superfluid helium film in the initial thermalization process, a geometry that severely limits detection efficiency, and the inability to trap deuterium. We are constructing a new apparatus based on buffer-gas cooling that will overcome these problems. To accelerate evaporative cooling, the thermalization rate is increased by simultaneously loading lithium and hydrogen into a 4.2 T anti-Helmholtz trap. Lithium accelerates evaporative cooling because the LiH elastic-scattering cross section is ∼1200 times larger than that of HH. Hydrogen and lithium will be produced by laser ablation of solid LiH in a 3He buffer gas held at temperatures of ∼350 mK. Because no wall collisions are needed for initial thermalization, ablating a solid sample of LiD should enable studies of deuterium. The apparatus is in the final stages of construction. We report on results of initial tests and discuss the new scientific opportunities made possible by this approach.PACS No.: 32.80.Pj

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19

Rouse, Ian, and Stefan Willitsch. "The energy distribution of an ion in a radiofrequency trap interacting with a nonuniform neutral buffer gas." Molecular Physics 117, no. 21 (March 14, 2019): 3120–31. http://dx.doi.org/10.1080/00268976.2019.1581952.

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20

Leuthner, H., and G. Werth. "Buffer-gas-cooled ion clouds in a classical Paul trap: superimposed stability diagrams and trapping capacity investigations." Applied Physics B 114, no. 1-2 (October 8, 2013): 89–98. http://dx.doi.org/10.1007/s00340-013-5657-1.

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21

Ovsyannikov, A. D., A. I. Shlokova, and A. A. Komarova. "Construction of Stability Regions in the Parameter Space in a Penning Trap with a Rotating Electric Field." Bulletin of Irkutsk State University. Series Mathematics 35 (2021): 49–59. http://dx.doi.org/10.26516/1997-7670.2021.35.49.

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The dynamics of particles in a Penning trap with a rotating dipole electric field and a buffer gas is considered. A transition is made to a coordinate system that rotates together with the electric field, which makes it possible to reduce the system of ordinary differential equations with periodic coefficients to a linear differential system with a constant matrix. Using one of the modifications of the Hurwitz stability criterionthe Lienard-Chipart criterion, the stability analysis (according to Lyapunov) of particle motions in the trap is carried out and the stability regions in the trap parameter space are found.Calculations were carried out for a trap with “typical” main parameters. The biggest degree of stability was obtained at frequencies of rotation of the field close to “resonant”. Small relative deviations from these frequencies led to a significant decrease in the degree of stability and loss of stability at “small” values of the amplitude of the rotating field. At the same time, it was possible to partially compensate this by increasing the amplitude of the rotating field, but only to certain limits, after which stability was again lost.

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22

WILLIAMS, T., J. STEPHENSONJR, and R. YOST. "The effects of pulsed introduction of buffer gas on ion storage and detection efficiencies in a quadrupole ion trap." Journal of the American Society for Mass Spectrometry 8, no. 5 (May 1997): 532–38. http://dx.doi.org/10.1016/s1044-0305(97)00011-1.

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23

Ovsyannikov, Alexander D. "Analysis of the dynamics of charged particles in an ideal Penning trap with a rotating field and a buffer gas." Vestnik of Saint Petersburg University. Applied Mathematics. Computer Science. Control Processes 15, no. 1 (2019): 62–75. http://dx.doi.org/10.21638/11701/spbu10.2019.105.

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24

Sugiyama, K., and J. Yoda. "Study of Yb/sup +/ trapped in a RF trap with light buffer gas by irradiation with resonant light (frequency standards)." IEEE Transactions on Instrumentation and Measurement 42, no. 2 (April 1993): 467–73. http://dx.doi.org/10.1109/19.278606.

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25

Wu, Hui-Fen, Li-Wei Chen, Jhen-Chen Wang, and Ya-Ping Lin. "Simulation of the Collisional Cooling Effect for Binary and Ternary Buffer Gas Mixtures in a Quadrupole Ion Trap Mass Spectrometer." European Journal of Mass Spectrometry 7, no. 1 (February 2001): 1–6. http://dx.doi.org/10.1255/ejms.374.

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26

Martinez, Franklin, Alexander Herlert, Gerrit Marx, Lutz Schweikhard, and Noelle Walsh. "Unintended Parametric Ejection of Ions from an Ion Cyclotron Resonance Trap by Two-Electrode Axialization." European Journal of Mass Spectrometry 15, no. 2 (April 2009): 283–91. http://dx.doi.org/10.1255/ejms.962.

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Azimuthal quadrupolar excitation is a commonly used technique in the field of ion cyclotron resonance mass spectrometry, in particular in combination with buffer-gas collisions to achieve axialization of the stored ions. If the quadrupolar excitation is applied with only one phase to a set of two opposing ring segments (rather than the “regular” method where two sets of electrodes are addressed with opposite polarities), parametric resonance effects at the frequencies 2μ z and μp = μ+ – μ– can lead to unintended ejection of ions from the trap. These parametric resonances have been revisited both theoretically and experimentally: multipole components of different azimuthal excitation schemes are derived by a simple vector representation of the excitation signal applied to the ring segments. Thus, parametric contributions can be easily identified, as demonstrated for the two-electrode and the four-electrode quadrupolar excitation schemes as well as further examples. In addition, the effect of the single-phase two-electrode quadrupolar excitation is demonstrated for storage and axialization of cluster ions.

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27

Jorudas, Justinas, Artūr Šimukovič, Maksym Dub, Maciej Sakowicz, Paweł Prystawko, Simonas Indrišiūnas, Vitalij Kovalevskij, Sergey Rumyantsev, Wojciech Knap, and Irmantas Kašalynas. "AlGaN/GaN on SiC Devices without a GaN Buffer Layer: Electrical and Noise Characteristics." Micromachines 11, no. 12 (December 20, 2020): 1131. http://dx.doi.org/10.3390/mi11121131.

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We report on the high-voltage, noise, and radio frequency (RF) performances of aluminium gallium nitride/gallium nitride (AlGaN/GaN) on silicon carbide (SiC) devices without any GaN buffer. Such a GaN–SiC hybrid material was developed in order to improve thermal management and to reduce trapping effects. Fabricated Schottky barrier diodes (SBDs) demonstrated an ideality factor n at approximately 1.7 and breakdown voltages (fields) up to 780 V (approximately 0.8 MV/cm). Hall measurements revealed a thermally stable electron density at N2DEG = 1 × 1013 cm−2 of two-dimensional electron gas in the range of 77–300 K, with mobilities μ = 1.7 × 103 cm2/V∙s and μ = 1.0 × 104 cm2/V∙s at 300 K and 77 K, respectively. The maximum drain current and the transconductance were demonstrated to be as high as 0.5 A/mm and 150 mS/mm, respectively, for the transistors with gate length LG = 5 μm. Low-frequency noise measurements demonstrated an effective trap density below 1019 cm−3 eV−1. RF analysis revealed fT and fmax values up to 1.3 GHz and 6.7 GHz, respectively, demonstrating figures of merit fT × LG up to 6.7 GHz × µm. These data further confirm the high potential of a GaN–SiC hybrid material for the development of thin high electron mobility transistors (HEMTs) and SBDs with improved thermal stability for high-frequency and high-power applications.

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28

Yoda, J., and K. Sugiyama. "Effect of buffer gas on the total number and the storage time of Ba ions trapped in a RF ion trap." IEEE Transactions on Instrumentation and Measurement 38, no. 2 (April 1989): 521–23. http://dx.doi.org/10.1109/19.192338.

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29

Hendricker, Alan D., Franco Basile, and Kent J. Voorhees. "A study of protein oxidative products using a pyrolysis-membrane inlet quadrupole ion trap mass spectrometer with air as the buffer gas." Journal of Analytical and Applied Pyrolysis 46, no. 1 (June 1998): 65–82. http://dx.doi.org/10.1016/s0165-2370(98)00070-9.

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30

Vedel, F., and J. André. "Computation for ions stored in a quadrupole R.F. TRAP cooled by a buffer gas. Influence of working conditions on space-charge effects." International Journal of Mass Spectrometry and Ion Processes 65, no. 1-2 (May 1985): 1–22. http://dx.doi.org/10.1016/0168-1176(85)85050-3.

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31

Lezhnin, S. I., S. A. Brednikhin, and D. V. Yurov. "Hybrid systems in the nuclear fuel cycle. Principles of operation and applications." Proceedings of the Mavlyutov Institute of Mechanics 9, no. 1 (2012): 116–20. http://dx.doi.org/10.21662/uim2012.1.022.

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The problem of utilization of nuclear fuel cycle waste is one of the main problems of modern nuclear energetics. In the Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of Sciences (RAS) in cooperation with the Nuclear Safety Institute of the RAS, a model of a subcritical hybrid system with a plasma neutron driver based on an open gas-dynamic trap is being developed to solve this problem. Modeling of the plasma behavior in the source was carried out using the zero-dimensional GENESYS code, which takes into account the processes of capturing of injected atoms by ions and the processes of Coulombic interactions with warm plasma. This code also contains a module for calculating the linear power of neutron emission along the axis of the trap using the Monte Carlo method. As a template for the fuel blanket, a homogenized blanket of the EFIT system was used. The calculation of neutron-physical characteristics was carried out using a static NMC code which uses a method of direct modeling of neutron trajectories. The article presents the results of optimization of parameters of this system. In particular, the optimal length of the source emission zone was determined and the dependence of the multiplication factor on the thickness of the buffer zone of the subcritical blanket was determined.

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32

Yang, Tiangang, Anyang Li, Gary K. Chen, Qian Yao, Arthur G. Suits, Hua Guo, Eric R. Hudson, and Wesley C. Campbell. "Isomer-specific kinetics of the C+ + H2O reaction at the temperature of interstellar clouds." Science Advances 7, no. 2 (January 2021): eabe4080. http://dx.doi.org/10.1126/sciadv.abe4080.

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The reaction C+ + H2O → HCO+/HOC+ + H is one of the most important astrophysical sources of HOC+ ions, considered a marker for interstellar molecular clouds exposed to intense ultraviolet or x-ray radiation. Despite much study, there is no consensus on rate constants for formation of the formyl ion isomers in this reaction. This is largely due to difficulties in laboratory study of ion-molecule reactions under relevant conditions. Here, we use a novel experimental platform combining a cryogenic buffer-gas beam with an integrated, laser-cooled ion trap and high-resolution time-of-flight mass spectrometer to probe this reaction at the temperature of cold interstellar clouds. We report a reaction rate constant of k = 7.7(6) × 10−9 cm3 s−1 and a branching ratio of formation η = HOC+/HCO+ = 2.1(4). Theoretical calculations suggest that this branching ratio is due to the predominant formation of HOC+ followed by isomerization of products with internal energy over the isomerization barrier.

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33

Weil, C., M. Nappi, C. D. Cleven, H. Wollnik, and R. G. Cooks. "Multiparticle Simulation of Ion Injection into the Quadrupole Ion Trap Under the Influence of Helium Buffer Gas Using Short Injection Times and DC Pulse Potentials." Rapid Communications in Mass Spectrometry 10, no. 7 (May 1996): 742–50. http://dx.doi.org/10.1002/(sici)1097-0231(199605)10:7<742::aid-rcm530>3.0.co;2-t.

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34

Berg, Max, Andreas Wolf, and Annemieke Petrignani. "Visible transitions from ground state H 3 + measured with high-sensitivity action spectroscopy." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 370, no. 1978 (November 13, 2012): 5028–40. http://dx.doi.org/10.1098/rsta.2012.0017.

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We report on the recent observation of new spectral lines of cold H ions lying well in the visible spectral region. Transitions from the two lowest ro–vibrational levels to final levels up to 16 700 cm −1 , almost half way to the dissociation limit, have been measured, involving up to eight vibrational quanta. The observed transitions are more than six orders of magnitude less intense than the fundamental band and yet another order of magnitude weaker than reached by previous sensitive action spectroscopy in the near-infrared region. The measurements were carried out in a cryogenic 22-pole ion trap with H ions cooled to their lowest rotational levels by helium buffer gas. Laser-induced chemical reactions lead to the formation of ArH + ions detected with single-ion sensitivity. These visible measurements, together with the previous near-infrared measurements, have helped to further develop empirically corrected calculations and have provided essential benchmarks for new ab initio calculations that now reach a spectroscopic accuracy of 0.1 cm −1 on average up to the highest observed transition. Highly sensitive action spectroscopy and the attained high-accuracy predictions will enable us to find and measure transitions even further into the visible region of H , paving the way towards the dissociation limit.

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35

Brumley, William C., Andrew H. Grange, Virginia Kelliher, Dennis B. Patterson, Alice Montcalm, Jack Glassman, and John W. Farley. "Environmental Screening of Acidic Compounds Based on Capillary Zone Electrophoresis/Laser-Induced Fluorescence Detection with Identification by Gas Chromatography/Mass Spectrometry and Gas Chromatography/High-Resolution Mass Spectrometry." Journal of AOAC INTERNATIONAL 83, no. 5 (September 1, 2000): 1059–67. http://dx.doi.org/10.1093/jaoac/83.5.1059.

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Abstract This paper describes the application of capillary zone electrophoresis/laser-induced fluorescence detection (CZE/LIF) to the discovery of acidic compounds in environmental matrixes or the screening of extracts for acidic components. Published studies indicate that coal-derived materials contain a significant fraction of acidic compounds relative to materials derived from petroleum and shales. Such compounds may be useful as marker compounds for site assessment and source apportionment issues, and their identification may be important in toxicological and other health issues. We used deep-UV light from the frequency-doubled Ar ion laser at 244 and 257 nm to study extracts of samples. The CZE/LIF technique possesses good sensitivity and therefore overcomes one of the limitations of CZE with UV detection. The present work depends on high pressure/temperature solvent extraction of polynuclear aromatic hydrocarbon (PNA)-contaminated soil, followed by separation using CZE. The anionic analytes were separated by using borate or phosphate buffer (pH 9.2–12.3) after a chemical class separation. Samples were also characterized by gas chromatography/mass spectrometry (GC/MS) using full scans at low resolution, and elemental compositions were determined unequivocally by GC/high-resolution MS (GC/HRMS) using mass peak profiling (MPP). The similarity of low-resolution electron ionization mass spectra for a standard, 1-hydroxypyrene, and for a series of compounds in a contaminated-soil extract suggested that several types of phenolic and hydroxy-PNAs were present, including hydroxylated derivatives of fluorenes, fluoranthenes, and pyrenes. GC/HRMS using MPP confirmed the elemental compositions of the hydroxyfluorenes and hydroxypyrenes (and presumably hydroxyfluoranthenes) as [C13H10O] and [C16H10O], respectively. A new version of the MPP software was written for the Finnigan-MAT 900S-Trap and was similar to that developed previously for the VG 250SE. Inclusion of a calibration ion in addition to a lock mass ion in the multiple-ion detection descriptor provided errors of <1 ppm for the 3 partial profiles of the analytes. A mass resolution of 31 000 was used to resolve the analyte signals from interferences evident in the full M+1 and M+2 profiles in the case of the hydroxyfluorenes. Derivatization was also performed to form the tert-butyldimethylsilyl derivatives of phenolic hydroxy groups as a further confirmation of structure.

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36

ARABSHAHI, H. "MONTE CARLO SIMULATIONS OF ELECTRON TRANSPORT IN WURTZITE PHASE GaN MESFET INCLUDING TRAPPING EFFECT." Modern Physics Letters B 20, no. 13 (May 30, 2006): 787–94. http://dx.doi.org/10.1142/s0217984906011037.

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Trapping of hot electron behavior by trap centers located in the buffer layer of a wurtzite phase GaN MESFET has been simulated using an ensemble Monte Carlo simulation. The simulated results show that trap centers are responsible for current collapse in GaN MESFET at low temperatures. These electrical traps degrade the performance of the device at low temperatures. On the other hand, at high temperatures, the electrical performances are improved due to electron emission from the trap centers. The simulated device geometries and doping are matched to the nominal parameters described for the experimental structures as closely as possible, and the predicted drain current and other electrical characteristics for the simulated device including the trapping center effects show much closer agreement with the available experimental data than without trap center effects.

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37

Potier, Clément, Jean-Claude Jacquet, Christian Dua, Audrey Martin, Michel Campovecchio, Mourad Oualli, Olivier Jardel, et al. "Highlighting trapping phenomena in microwave GaN HEMTs by low-frequencyS-parameters." International Journal of Microwave and Wireless Technologies 7, no. 3-4 (February 5, 2015): 287–96. http://dx.doi.org/10.1017/s1759078715000094.

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This paper presents an original characterization method of trapping phenomena in gallium nitride high electron mobility transistors (GaN HEMTs). This method is based on the frequency dispersion of the output-admittance that is characterized by low-frequency S-parameter measurements. As microwave performances of GaN HEMTs are significantly affected by trapping effects, trap characterization is essential for this power technology. The proposed measurement setup and the trap characterization method allow us to determine the activation energy Ea and the capture cross-section σnof the identified traps. Three original characterizations are presented here to investigate the particular effects of bias, ageing, and light, respectively. These measurements are illustrated through different technologies such as AlGaN/GaN and InAlN/GaN HEMTs with non-intentionally doped or carbon doped GaN buffer layers. The extracted trap signatures are intended to provide an efficient feedback to the technology developments

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38

Im, Ki-Sik, Mallem Siva Pratap Reddy, Yeo Jin Choi, Youngmin Hwang, Sung Jin An, and Jea-Seung Roh. "Investigation of 1/f and Lorentzian Noise in TMAH-treated Normally-Off GaN MISFETs." Crystals 10, no. 8 (August 18, 2020): 717. http://dx.doi.org/10.3390/cryst10080717.

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A tetramethyl ammonium hydroxide (TMAH)-treated normally-off Gallum nitride (GaN) metal-insulator-semiconductor field-effect transistor (MISFET) was fabricated and characterized using low-frequency noise (LFN) measurements in order to find the conduction mechanism and analyze the trapping behavior into the gate insulator as well as the GaN buffer layer. At the on-state, the noise spectra in the fabricated GaN device were 1/fγ properties with γ ≈ 1, which is explained by correlated mobility fluctuations (CMF). On the other hand, the device exhibited Lorentzian or generation-recombination (g-r) noises at the off-state due to deep-level trapping/de-trapping into the GaN buffer layer. The trap time constants (τi) calculated from the g-r noises became longer when the drain voltage increased up to 5 V, which was attributed to deep-level traps rather than shallow traps. The severe drain lag was also investigated from pulsed I-V measurement, which is supported by the noise behavior observed at the off-state.

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39

Song, Yu-Lin, Manoj Kumar Reddy, Luh-Maan Chang, and Gene Sheu. "Physics-Based TCAD Simulation and Calibration of 600 V GaN/AlGaN/GaN Device Characteristics and Analysis of Interface Traps." Micromachines 12, no. 7 (June 26, 2021): 751. http://dx.doi.org/10.3390/mi12070751.

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This study proposes an analysis of the physics-based TCAD (Technology Computer-Aided Design) simulation procedure for GaN/AlGaN/GaN HEMT (High Electron Mobility Transistor) device structures grown on Si (111) substrate which is calibrated against measurement data. The presence of traps and activation energies in the device structure will impact the performance of a device, the source of traps and position of traps in the device remains as a complex exercise until today. The key parameters for the precise tuning of threshold voltage (Vth) in GaN transistors are the control of the positive fixed charges −5 × 1012 cm−2, donor-like traps −3 × 1013 cm−2 at the nitride/GaN interfaces, the energy of the donor-like traps 1.42 eV below the conduction band and the acceptor traps activation energy in the AlGaN layer and buffer regions with 0.59 eV below the conduction band. Hence in this paper, the sensitivity of the trap mechanisms in GaN/AlGaN/GaN HEMT transistors, understanding the absolute vertical electric field distribution, electron density and the physical characteristics of the device has been investigated and the results are in good agreement with GaN experimental data.

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Benvegnù, Agostino, Davide Bisi, Sylvain Laurent, Matteo Meneghini, Gaudenzio Meneghesso, Denis Barataud, Enrico Zanoni, and Raymond Quere. "Drain current transient and low-frequency dispersion characterizations in AlGaN/GaN HEMTs." International Journal of Microwave and Wireless Technologies 8, no. 4-5 (April 7, 2016): 663–72. http://dx.doi.org/10.1017/s1759078716000398.

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This paper presents a detailed trap investigation based on combined pulsed I/V measurements, drain current transient (DCT) measurements and low-frequency dispersion measurements of transconductance (LF Y21) and output conductance (LF Y22). DCT characterization is carried out over a 7-decade time scale. LF Y21and Y22measurements are carried out over the frequency range from 100 Hz to 1 GHz. These combined measurements were performed at several temperatures for AlGaN/GaN high electron mobility transistors under class AB bias condition and allowed the extraction of the activation energy (Ea) and the capture cross section (σc) of the identified traps. Extensive measurements of these characteristics as a function of device bias are reported in this work to understand the dynamic trap behavior. This paper demonstrated a correlation between LF small-signal (LF Y21and Y22) and large-signal voltage steps (DCT) results. These measurements allow identifying the same 0.64 eV deep level, attributed to a native defect of GaN, possibly located in the buffer layer.

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Tajalli, Alaleh, Matteo Meneghini, Sven Besendörfer, Riad Kabouche, Idriss Abid, Roland Püsche, Joff Derluyn, et al. "High Breakdown Voltage and Low Buffer Trapping in Superlattice GaN-on-Silicon Heterostructures for High Voltage Applications." Materials 13, no. 19 (September 25, 2020): 4271. http://dx.doi.org/10.3390/ma13194271.

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The aim of this work is to demonstrate high breakdown voltage and low buffer trapping in superlattice GaN-on-Silicon heterostructures for high voltage applications. To this aim, we compared two structures, one based on a step-graded (SG) buffer (reference structure), and another based on a superlattice (SL). In particular, we show that: (i) the use of an SL allows us to push the vertical breakdown voltage above 1500 V on a 5 µm stack, with a simultaneous decrease in vertical leakage current, as compared to the reference GaN-based epi-structure using a thicker buffer thickness. This is ascribed to the better strain relaxation, as confirmed by X-Ray Diffraction data, and to a lower clustering of dislocations, as confirmed by Defect Selective Etching and Cathodoluminescence mappings. (ii) SL-based samples have significantly lower buffer trapping, as confirmed by substrate ramp measurements. (iii) Backgating transient analysis indicated that traps are located below the two-dimensional electron gas, and are related to CN defects. (iv) The signature of these traps is significantly reduced on devices with SL. This can be explained by the lower vertical leakage (filling of acceptors via electron injection) or by the slightly lower incorporation of C in the SL buffer, due to the slower growth process. SL-based buffers therefore represent a viable solution for the fabrication of high voltage GaN transistors on silicon substrate, and for the simultaneous reduction of trapping processes.

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Marjanović, Srđan, and Zoran Lj Petrović. "Monte Carlo modeling and optimization of buffer gas positron traps." Plasma Sources Science and Technology 26, no. 2 (January 13, 2017): 024003. http://dx.doi.org/10.1088/1361-6595/aa5308.

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Im, Ki-Sik, Jae-Hoon Lee, Yeo Jin Choi, and Sung Jin An. "Effects of GaN Buffer Resistance on the Device Performances of AlGaN/GaN HEMTs." Crystals 10, no. 9 (September 22, 2020): 848. http://dx.doi.org/10.3390/cryst10090848.

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We investigated the effects of GaN buffer resistance of AlGaN/GaN high-electron-mobility transistors (HEMTs) on direct current (DC), low-frequency noise (LFN), and pulsed I-V characterization performances. The devices with the highest GaN buffer resistance were grown on sapphire substrate using two-step growth temperature method without additional compensation doping. The proposed device exhibited the degraded off-state leakage current due to the improved GaN buffer quality compared to the reference devices with relative low buffer resistance, which is confirmed by high resolution X-ray diffraction (HRXRD). However, the proposed device with deep-level defects in GaN buffer layer showed the reduced hysteresis (∆Vth), increased breakdown voltage (BV), and enhanced pulse I-V characteristics. Regardless of GaN buffer resistance, all devices clearly showed 1/f behavior with carrier number fluctuations (CNF) at on-state but followed 1/f2 characteristic at off-state. From the 1/f2 noise characteristics, the extracted trap time constant (τi) of the proposed device can be obtained to be 10 ms, which is shorter than those of the reference devices because of the full compensation of deep-level defects in the GaN buffer layer.

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Gerlich, D., and G. Borodi. "Buffer gas cooling of polyatomic ions in rf multi-electrode traps." Faraday Discussions 142 (2009): 57. http://dx.doi.org/10.1039/b820977d.

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deCarvalho, R., J. M. Doyle, B. Friedrich, T. Guillet, J. Kim, D. Patterson, and J. D. Weinstein. "Buffer-gas loaded magnetic traps for atoms and molecules: A primer." European Physical Journal D 7, no. 3 (1999): 289. http://dx.doi.org/10.1007/s100530050572.

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Brahms, Nathan, Timur V. Tscherbul, Peng Zhang, Jacek Kłos, Robert C. Forrey, Yat Shan Au, H. R. Sadeghpour, A. Dalgarno, John M. Doyle, and Thad G. Walker. "Formation and dynamics of van der Waals molecules in buffer-gas traps." Physical Chemistry Chemical Physics 13, no. 42 (2011): 19125. http://dx.doi.org/10.1039/c1cp21317b.

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Hemmerling, Boerge, Garrett K. Drayna, Eunmi Chae, Aakash Ravi, and John M. Doyle. "Buffer gas loaded magneto-optical traps for Yb, Tm, Er and Ho." New Journal of Physics 16, no. 6 (June 30, 2014): 063070. http://dx.doi.org/10.1088/1367-2630/16/6/063070.

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Horio, Kazushige, and Atsushi Nakajima. "Buffer-trap and surface-state effects on gate lag in AlGaN/GaN HEMTs." physica status solidi (c) 7, no. 7-8 (May 14, 2010): 1931–33. http://dx.doi.org/10.1002/pssc.200983418.

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Zagni, Nicolò, Alessandro Chini, Francesco Maria Puglisi, Paolo Pavan, and Giovanni Verzellesi. "On the Modeling of the Donor/Acceptor Compensation Ratio in Carbon-Doped GaN to Univocally Reproduce Breakdown Voltage and Current Collapse in Lateral GaN Power HEMTs." Micromachines 12, no. 6 (June 16, 2021): 709. http://dx.doi.org/10.3390/mi12060709.

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The intentional doping of lateral GaN power high electron mobility transistors (HEMTs) with carbon (C) impurities is a common technique to reduce buffer conductivity and increase breakdown voltage. Due to the introduction of trap levels in the GaN bandgap, it is well known that these impurities give rise to dispersion, leading to the so-called “current collapse” as a collateral effect. Moreover, first-principles calculations and experimental evidence point out that C introduces trap levels of both acceptor and donor types. Here, we report on the modeling of the donor/acceptor compensation ratio (CR), that is, the ratio between the density of donors and acceptors associated with C doping, to consistently and univocally reproduce experimental breakdown voltage (VBD) and current-collapse magnitude (ΔICC). By means of calibrated numerical device simulations, we confirm that ΔICC is controlled by the effective trap concentration (i.e., the difference between the acceptor and donor densities), but we show that it is the total trap concentration (i.e., the sum of acceptor and donor densities) that determines VBD, such that a significant CR of at least 50% (depending on the technology) must be assumed to explain both phenomena quantitatively. The results presented in this work contribute to clarifying several previous reports, and are helpful to device engineers interested in modeling C-doped lateral GaN power HEMTs.

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ARABSHAHI, H., and M. H. GHASEMIAN. "INFLUENCE OF POLARIZATION CHARGES AND ELECTRON TRAPPING IN THE BUFFER LAYER IN WURTZITE PHASE AlGaN/GaN HFETs." Modern Physics Letters B 20, no. 22 (September 30, 2006): 1397–404. http://dx.doi.org/10.1142/s0217984906011608.

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Ensemble Monte Carlo simulations have been performed to model electron transport in wurtzite phase AlGaN/GaN heterojunction FETs. Planar Al 0.2 Ga 0.8 N/GaN HFET structures with a 78 nm Al 0.2 Ga 0.8 N pseudomorphically strained layer were simulated, where the spontaneous and piezoelectric polarization effects were taken into account. Trap centers located in the buffer layer has also been simulated to include the effect of trapping levels on current collapse in GaN HFETs. The polarization effects was shown to not only increase the current density, but also improve the electron transport in the interface layer by inducing a higher electron density to the positive polarized sheet and away from the buffer layer.

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Journal articles on the topic 'Buffer gas trap'

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