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Sample records for highly ionized gas

  1. Highly ionized atoms in cooling gas

    NASA Technical Reports Server (NTRS)

    Edgar, R. J.; Chevalier, R. A.

    1986-01-01

    The ionization of low density gas cooling from a high temperature was calculated. The evolution during the cooling is assumed to be isochoric, isobaric, or a combination of these cases. The calculations are used to predict the column densities and ultraviolet line luminosities of highly ionized atoms in cooling gas. In a model for cooling of a hot galactic corona, it is shown that the observed value of N(N V) can be produced in the cooling gas, while the predicted value of N(Si IV) falls short of the observed value by a factor of about 5. The same model predicts fluxes of ultraviolet emission lines that are a factor of 10 lower than the claimed detections of Feldman, Brune, and Henry. Predictions are made for ultraviolet lines in cooling flows in early-type galaxies and clusters of galaxies. It is shown that the column densities of interest vary over a fairly narrow range, while the emission line luminosities are simply proportional to the mass inflow rate.

  2. Highly ionized gas in the Galactic halo

    NASA Technical Reports Server (NTRS)

    Shull, J. Michael; Slavin, Jonathan D.

    1994-01-01

    We reexamine the values of electron density n(sub e) and gas pressure P/k in the interstellar medium (ISM) of the Galactic halo, as inferred from C IV emission and absorption lines and using current C IV atomic data. In a homogeneous model with 4.7 less than or equal to log T less than or equal to 5.3, the data are consistent with 0.01 less than or equal to n(sub e) less than or equal to 0.02/cu cm and 2200 less than or equal to P/k less than or equal to 3700/cu cm K, a factor of 2-3 higher than advocated by Martin & Bowyer (1990) and comparable to the thermal pressure in the disk. If some of the C IV absorption arises from nonemitting, photoionized gas, then the inferred density and pressure will increase accordingly. The volume filling factor for homogeneous models ranges from 0.5% to 5%. Because of the constraints arising from filling factor and radiated power, most of the C IV must arise from gas near the peak of the cooling curve, at log t less than or equal to 5.6. We relate both emission-line and absorption-line observations to recent models in which turbulent mixing layers and isobarically cooling supernova remnants (SNRs) provide significant amounts of halo gas at approximately 10(exp 5.3) K and process 20-40 solar mass/yr with a power of approximately 10(exp 41) ergs/sec. Since the observed C IV and N V absorption scale heights have been reported to differ, at 4.9 kpc and 1.6 kpc, respectively, we examine inhomogeneous models with different exponential scale heights of T, P, and SN energy input. The ISM may change its character with distance above the Galactic plane, as superbubbles and mixing layers dominate over isolated SNRs as the source of the C IV. For appropiate scale heights, the midplane pressure is twice the homogeneous values quoted above. The O IV lambda 1034 diffuse emission line, which can be used as a temperature diagnostic of the hot gas, is predicted to be comparable in strength to that of C IV lambda 1549 (approximately 6000 photons

  3. Ionization chamber for measurements of high-level tritium gas

    SciTech Connect

    Carstens, D.H.W.; David, W.R.

    1980-01-01

    The construction and calibration of a simple ionization-chamber apparatus for measurement of high level tritium gas is described. The apparatus uses an easily constructed but rugged chamber containing the unknown gas and an inexpensive digital multimeter for measuring the ion current. The equipment after calibration is suitable for measuring 0.01 to 100% tritium gas in hydrogen-helium mixes with an accuracy of a few percent. At both the high and low limits of measurements deviations from the predicted theoretical current are observed. These are briefly discussed.

  4. Highly Ionized Gas as a Diagnostic of the Inner NLR

    NASA Astrophysics Data System (ADS)

    Ward, M. J.; Mullaney, J.; Jin, C.; Davies, R.

    2010-05-01

    The spectra of AGN, from the ultraviolet to the near infrared, exhibit emission lines covering a wide range of ionization states, from neutral species such as [O i] λ 6300, up to [Fe iv] λ 5303. Here we report on some recent studies of the properties of highly ionized lines (HILs), plus two case studies of individual objects. Future IFU observations at high spatial and good spectral resolution will probe the excitation and kinematics of the gas in the zone between the extended NLR and unresolved BLR. Multi-component SED fitting can be used to link the source of photoionization with the strengths and ratios of the HILs.

  5. Ionization front in a high-current gas dischargea)

    NASA Astrophysics Data System (ADS)

    Choueiri, Edgar Y.; Randolph, Thomas M.

    2007-03-01

    Spectroscopic measurements of ion/neutral density ratio profiles are made inside the high-current, low-pressure discharge of a coaxial magnetoplasmadynamic thruster and show the existence of a thin ionization front, upstream in the discharge, that effectively ionizes the incoming gas to ionization levels above 50%. The measurements allow an estimate of the width of this ionization front to be on the order of a few millimeters. Due to the known existence of microturbulence in the plasma, which can produce suprathermal electrons, an explanation of the measurements based on the existence of a suprathermal tail in the electron energy distribution function is sought. A theoretical model for the width of the ionization front is combined with a multilevel excitation model for argon and shows that a Maxwellian electron distribution function cannot account for the small length scale of the ionization front, and that the latter is more consistent with an electron distribution function having a suprathermal population, the magnitude of which is estimated by comparing the model to the experiments.

  6. Ionization front in a high-current gas discharge

    NASA Astrophysics Data System (ADS)

    Choueiri, Edgar Y.; Randolph, Thomas M.

    2007-02-01

    Spectroscopic measurements of ion/neutral density ratio profiles are made inside the high-current, low-pressure discharge of a coaxial magnetoplasmadynamic thruster and show the existence of a thin ionization front, upstream in the discharge, that effectively ionizes the incoming gas to ionization levels above 50%. The measurements allow an estimate of the width of this ionization front to be on the order of a few millimeters. Due to the known existence of microturbulence in the plasma, which can produce suprathermal electrons, an explanation of the measurements based on the existence of a suprathermal tail in the electron energy distribution function is sought. A theoretical model for the width of the ionization front is combined with a multilevel excitation model for argon and shows that a Maxwellian electron distribution function cannot account for the small length scale of the ionization front, and that the latter is more consistent with an electron distribution function having a suprathermal population, the magnitude of which is estimated by comparing the model to the experiments.

  7. Gentle protein ionization assisted by high-velocity gas flow.

    PubMed

    Yang, Pengxiang; Cooks, R Graham; Ouyang, Zheng; Hawkridge, Adam M; Muddiman, David C

    2005-10-01

    Gentle protein electrospray ionization is achieved using the high-velocity gas flow of an air amplifier to improve desolvation in conventional ESI and generate intact folded protein ions in the gas phase. Comparisons are made between the ESI spectra of a number of model proteins, including ubiquitin, cytochrome c, lysozyme, and myoglobin, over a range of pH values under optimized conditions, with and without using an air amplifier to achieve high-velocity gas flow. Previously reported increased ion signals are confirmed. In addition, the peaks recorded using the air amplifier are shown to be narrower, corresponding to more complete desolvation. Significant changes in the charge-state distribution also are observed, with a shift to lower charge state at high-velocity flow. The relationship between the observed charge-state distribution and protein conformation was explored by comparing the charge-state shifts and the distributions of charge states for proteins that are or are not stable in their native conformations in low pH solutions. The data suggest retention of native or nativelike protein conformations using the air amplifier in all cases examined. This is explained by a mechanism in which the air amplifier rapidly creates small droplets from the original large ESI droplets and these microdroplets then desolvate without a significant decrease in pH, resulting in retention of the folded protein conformations. Furthermore, the holoform of ionized myoglobin is visible at pH 3.5, a much lower value than the minimum needed to see this form in conventional ESI. These results provide evidence for the importance of the conditions used in the desolvation process for the preservation of the protein conformation and suggest that the conditions achieved when using high-velocity gas flows to assist droplet evaporation and ion desolvation are much gentler than those in conventional ESI experiments.

  8. The highly ionized, high-velocity gas in NGC 6231

    NASA Astrophysics Data System (ADS)

    Massa, Derck

    2017-02-01

    It is well known that clusters of massive stars are influenced by the presence of strong winds, that they are sources of diffuse X-rays from shocked gas, and that this gas can be vented into the surrounding region or the halo through the champagne effect. However, the details of how these different environments interact and evolve are far from complete. This paper attributes the broad C IVλλ1500 absorption features (extending to -1900 km s-1) that are seen in the spectra of main sequence B stars in NGC 6231 to gas in the cluster environment and not the B stars themselves. It is shown that the presence of a WC star, WR 79, in the cluster makes this gas detectable because its wind enriches the cluster gas with carbon. Given the available data, it is not clear whether the absorbing gas is simply the far wind of WR 79 or a collective cluster wind enriched by carbon from the wind of WR 79. If it is simply due to the wind, then this wind must flow, unimpeded for more than 2 pc, suggesting that the inner region of the cluster is nearly devoid of obstructing material. If it is actually a collective wind from the cluster, then we could be witnessing an important stage of galactic feedback. In either case, the observations provide a unique and significant piece to the puzzle of how massive, open clusters evolve.

  9. Properties of the highly ionized disk and halo gas toward two distant high-latitude stars

    NASA Technical Reports Server (NTRS)

    Savage, Blair D.; Sembach, K. R.

    1994-01-01

    Goddard High Resolution Spectrograph (GHRS) intermediate -resolution observations of S III, Si III, Al III, Si IV, C IV, and N V absorption along the sight lines to HD 18100 (l = 217.9 deg, b = -62.7, d = 3.1 kpc, z = -2.8 kpc) and HD 100340 (l = 258.9 deg, b = +61.2 deg, d = 5.3 kpc, z = 4.6 kpc) are presented. These small science aperture spectra have resolutions ranging from 11 to 20 km/s full width at half maximum (FWHM) and S/N from 30 to 65 per diode substep. Strong absorption by moderately and highly ionized gas is seen in each direction. The absorption in the direction of the south Galactic polar region (HD 18100) is kinematically simple, while the absorption in the direction of north Galactic polar region (HD 100304) is kinematically complex. In each case the absorption by the highly ionized gas lies within the velocity range of absorption by neutral and weakly ionized gas. Along each sight line, the velocity dispersion determined from the unsaturated absorption lines increases with the energy required to create each ion. The logarithmic column densities for Al III, Si IV, C IV, and N V are log N(atoms/sq cm = 12.71, 13.10, 13.58, and 12.75 toward HD 18100 and log N = 12.88, 13.31, 13.83, and 13.04 toward HD 100340. Average ionic ratios among these species are very similar along the two sight lines. Differences in profile shape between the absorption for AL II, Si IV, C IV, and N V provide additional support for the claim of Savage, Sembach, & Cardelli (1994) that there exists two types of highly ionized gas in the interstellar medium. One type of highly ionized gas is responsible for the structured Si IV absorption and part of the C IV absorption. In this gas N(C IV)/N(Si IV) approximately 3.0 and N(C IV)/N(N V) greater than 6. The absorption by this gas seems to be associated with some type of self-regulating interface or mixing layer between the warm and hot interstellar medium. The other type of highly ionized gas is responsible for most of the N V

  10. Gas ionization induced by a high speed plasma injection in space

    NASA Technical Reports Server (NTRS)

    Sasaki, S.; Kawashima, N.; Kuriki, K.; Yanagisawa, M.; Obayashi, T.; Roberts, W. T.; Reasoner, D. L.; Taylor, W. W. L.

    1986-01-01

    Gas ionization induced by a fast plasma injection has been observed with the Space Experiments with Particle Accelerators (SEPAC) Experiment on Spacelab-1. When an impulsive high-density plasma was injected from the orbiter, waves near the lower-hybrid frequency were enhanced, and the surrounding gas drifting with the orbiter was ionized for several tens of milliseconds after the plasma injection. The long-duration gas ionization was observed only when the plasma flux incoming to the orbiter cargo bay and the orbital velocity perpendicular to the magnetic field were relatively large. This effect has been explained by the concept of critical velocity ionization (CVI) for the gas drifting with the orbiter, although the gas velocity perpendicular to the magnetic field was less than the Alfven critical velocity.

  11. Ionization processes in combined high-voltage nanosecond - laser discharges in inert gas

    NASA Astrophysics Data System (ADS)

    Starikovskiy, Andrey; Shneider, Mikhail; PU Team

    2016-09-01

    Remote control of plasmas induced by laser radiation in the atmosphere is one of the challenging issues of free space communication, long-distance energy transmission, remote sensing of the atmosphere, and standoff detection of trace gases and bio-threat species. Sequences of laser pulses, as demonstrated by an extensive earlier work, offer an advantageous tool providing access to the control of air-plasma dynamics and optical interactions. The avalanche ionization induced in a pre-ionized region by infrared laser pulses where investigated. Pre-ionization was created by an ionization wave, initiated by high-voltage nanosecond pulse. Then, behind the front of ionization wave extra avalanche ionization was initiated by the focused infrared laser pulse. The experiment was carried out in argon. It is shown that the gas pre-ionization inhibits the laser spark generation under low pressure conditions.

  12. High-field plasma acceleration in a high-ionization-potential gas

    DOE PAGES

    Corde, S.; Adli, E.; Allen, J. M.; ...

    2016-06-17

    Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. In our research, we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by upmore » to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ~150 GV m-1, over ~20 cm. Lastly, the results open new possibilities for the design of particle beam drivers and plasma sources.« less

  13. High-field plasma acceleration in a high-ionization-potential gas

    SciTech Connect

    Corde, S.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Clausse, B.; Clayton, C. E.; Delahaye, J. P.; Frederico, J.; Gessner, S.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Vafaei-Najafabadi, N.; Walz, D.; Yakimenko, V.

    2016-06-17

    Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. In our research, we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ~150 GV m-1, over ~20 cm. Lastly, the results open new possibilities for the design of particle beam drivers and plasma sources.

  14. High-field plasma acceleration in a high-ionization-potential gas

    PubMed Central

    Corde, S.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Clausse, B.; Clayton, C. E.; Delahaye, J. P.; Frederico, J.; Gessner, S.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Vafaei-Najafabadi, N.; Walz, D.; Yakimenko, V.

    2016-01-01

    Plasma accelerators driven by particle beams are a very promising future accelerator technology as they can sustain high accelerating fields over long distances with high energy efficiency. They rely on the excitation of a plasma wave in the wake of a drive beam. To generate the plasma, a neutral gas can be field-ionized by the head of the drive beam, in which case the distance of acceleration and energy gain can be strongly limited by head erosion. Here we overcome this limit and demonstrate that electrons in the tail of a drive beam can be accelerated by up to 27 GeV in a high-ionization-potential gas (argon), boosting their initial 20.35 GeV energy by 130%. Particle-in-cell simulations show that the argon plasma is sustaining very high electric fields, of ∼150 GV m−1, over ∼20 cm. The results open new possibilities for the design of particle beam drivers and plasma sources. PMID:27312720

  15. Investigation of combwax of honeybees with high-temperature gas chromatography and high-temperature gas chromatography-chemical ionization mass spectrometry. II: High-temperature gas chromatography-chemical ionization mass spectrometry.

    PubMed

    Aichholz, R; Lorbeer, E

    2000-06-23

    Crude combwax of six various honey bee species have been analyzed by high-temperature gas chromatography (HTGC)-chemical ionization mass spectrometry after a two-step silylation procedure. An optimized chromatographic procedure, described previously, enables the separation of high-molecular mass lipid compounds resulting in a characteristic fingerprint of the combwaxes of different honeybee species. The coupling of HTGC to mass spectrometry requires appropriate instrumentation in order to achieve sufficient sensitivity at high elution temperatures and avoid loss of chromatographic resolution. Chemical ionization was carried out using methane as reagent gas in order to determine the molecular mass of the individual compounds by means of abundant quasi molecular ions. To confirm the presence of unsaturated wax esters, ammonia was used as reagent gas. More than 80 lipid constituents were separated and characterized by their mass spectra. Representative chemical ionization mass spectra of individual compounds are presented. Both, HTGC-flame ionization detection data and the results of the HTGC-mass spectrometric investigations enabled a rapid profiling of the individual classes of compounds in crude combwaxes.

  16. Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion

    NASA Astrophysics Data System (ADS)

    Ferrer, R.; Barzakh, A.; Bastin, B.; Beerwerth, R.; Block, M.; Creemers, P.; Grawe, H.; de Groote, R.; Delahaye, P.; Fléchard, X.; Franchoo, S.; Fritzsche, S.; Gaffney, L. P.; Ghys, L.; Gins, W.; Granados, C.; Heinke, R.; Hijazi, L.; Huyse, M.; Kron, T.; Kudryavtsev, Yu.; Laatiaoui, M.; Lecesne, N.; Loiselet, M.; Lutton, F.; Moore, I. D.; Martínez, Y.; Mogilevskiy, E.; Naubereit, P.; Piot, J.; Raeder, S.; Rothe, S.; Savajols, H.; Sels, S.; Sonnenschein, V.; Thomas, J.-C.; Traykov, E.; van Beveren, C.; van den Bergh, P.; van Duppen, P.; Wendt, K.; Zadvornaya, A.

    2017-02-01

    Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we demonstrate the on-line application of atomic laser ionization spectroscopy in a supersonic gas jet, a technique suited for high-precision studies of the ground- and isomeric-state properties of nuclei located at the extremes of stability. The technique is characterized in a measurement on actinium isotopes around the N=126 neutron shell closure. A significant improvement in the spectral resolution by more than one order of magnitude is achieved in these experiments without loss in efficiency.

  17. Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion

    PubMed Central

    Ferrer, R.; Barzakh, A.; Bastin, B.; Beerwerth, R.; Block, M.; Creemers, P.; Grawe, H.; de Groote, R.; Delahaye, P.; Fléchard, X.; Franchoo, S.; Fritzsche, S.; Gaffney, L. P.; Ghys, L.; Gins, W.; Granados, C.; Heinke, R.; Hijazi, L.; Huyse, M.; Kron, T.; Kudryavtsev, Yu.; Laatiaoui, M.; Lecesne, N.; Loiselet, M.; Lutton, F.; Moore, I. D.; Martínez, Y.; Mogilevskiy, E.; Naubereit, P.; Piot, J.; Raeder, S.; Rothe, S.; Savajols, H.; Sels, S.; Sonnenschein, V.; Thomas, J-C; Traykov, E.; Van Beveren, C.; Van den Bergh, P.; Van Duppen, P.; Wendt, K.; Zadvornaya, A.

    2017-01-01

    Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we demonstrate the on-line application of atomic laser ionization spectroscopy in a supersonic gas jet, a technique suited for high-precision studies of the ground- and isomeric-state properties of nuclei located at the extremes of stability. The technique is characterized in a measurement on actinium isotopes around the N=126 neutron shell closure. A significant improvement in the spectral resolution by more than one order of magnitude is achieved in these experiments without loss in efficiency. PMID:28224987

  18. High-Ionization Gas Associated with a Supershell Surrounding the Perseus OB1 Association

    NASA Astrophysics Data System (ADS)

    Knauth, D. C.; Howk, J. C.; Sembach, K. R.; Lauroesch, J. T.; Meyer, D. M.

    2002-05-01

    We present Far-Ultraviolet Spectroscopic Explorer (FUSE) and Space Telescope Imaging Spectrograph (STIS) observations of high-ionization interstellar absorption toward HD 14434, an O5.5 V star in the Per OB1 Association. This star lies in the direction of the H I supershell GS139-03-69 (Heiles 1979, ApJ, 229, 533). In addition, a supershell-like bubble is detected from WHAM maps of the Perseus arm (Madsen, Haffner, & Reynolds astro-ph/0112232). We detect intermediate velocity interstellar Si IV and C IV absorption centered at VLSR = -73 km s-1, while low-ionization Perseus arm gas is detected at approximately -50 km s-1. Neither N V nor O VI is detected at these velocities, although Fe III, a tracer of warm ionized gas, is seen. The column densities in the -73 km s-1 component are log N(C IV}) = 13.93 +/- 0.02, log N(Si IV}) = 13.35 +/- 0.02, log N(N V}) <= 12.65, and log N(O VI}) <= 13.32. The observed C IV/Si IV ratio of 3.8 +/- 0.3 is similar to the Galactic average. Analysis of the C IV and Si IV line widths yields a temperature of T ~ 12,000 K for this component. No C IV or Si IV is produced via collisions at such low temperatures. We explore two models for the origins of the intermediate velocity C IV and Si IV absorption: photoionization or non-equilibrium collisional processes. Either of these could be related to the origins of the high-ionization gas with a supershell. This work is based on data obtained for the Guaranteed Time Team by the NASA-CNES-CSA FUSE mission. Financial support has been provided by NASA contract NAS5-32985.

  19. Highly ionized atoms in cooling gas. [in model for cooling of hot Galactic corona

    NASA Technical Reports Server (NTRS)

    Edgar, Richard J.; Chevalier, Roger A.

    1986-01-01

    The ionization of low density gas cooling from a high temperature was calculated. The evolution during the cooling is assumed to be isochoric, isobaric, or a combination of these cases. The calculations are used to predict the column densities and ultraviolet line luminosities of highly ionized atoms in cooling gas. In a model for cooling of a hot galactic corona, it is shown that the observed value of N(N V) can be produced in the cooling gas, while the predicted value of N(Si IV) falls short of the observed value by a factor of about 5. The same model predicts fluxes of ultraviolet emission lines that are a factor of 10 lower than the claimed detections of Feldman, Bruna, and Henry. Predictions are made for ultraviolet lines in cooling flows in early-type galaxies and clusters of galaxies. It is shown that the column densities of interest vary over a fairly narrow range, while the emission line luminosities are simply proportional to the mass inflow rate.

  20. High performance mini-gas chromatography-flame ionization detector system based on micro gas chromatography column

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaofeng; Sun, Jianhai; Ning, Zhanwu; Zhang, Yanni; Liu, Jinhua

    2016-04-01

    Monitoring Volatile organic compounds (VOCs) was a very important measure for preventing environmental pollution, therefore, a mini gas chromatography (GC) flame ionization detector (FID) system integrated with a mini H2 generator and a micro GC column was developed for environmental VOC monitoring. In addition, the mini H2 generator was able to make the system explode from far away due to the abandoned use of a high pressure H2 source. The experimental result indicates that the fabricated mini GC FID system demonstrated high repeatability and very good linear response, and was able to rapidly monitor complicated environmental VOC samples.

  1. High performance mini-gas chromatography-flame ionization detector system based on micro gas chromatography column.

    PubMed

    Zhu, Xiaofeng; Sun, Jianhai; Ning, Zhanwu; Zhang, Yanni; Liu, Jinhua

    2016-04-01

    Monitoring Volatile organic compounds (VOCs) was a very important measure for preventing environmental pollution, therefore, a mini gas chromatography (GC) flame ionization detector (FID) system integrated with a mini H2 generator and a micro GC column was developed for environmental VOC monitoring. In addition, the mini H2 generator was able to make the system explode from far away due to the abandoned use of a high pressure H2 source. The experimental result indicates that the fabricated mini GC FID system demonstrated high repeatability and very good linear response, and was able to rapidly monitor complicated environmental VOC samples.

  2. Determination of nitrogen monoxide in high purity nitrogen gas with an atmospheric pressure ionization mass spectrometer

    NASA Technical Reports Server (NTRS)

    Kato, K.

    1985-01-01

    An atmospheric pressure ionization mass spectrometric (API-MS) method was studied for the determination of residual NO in high purity N2 gas. The API-MS is very sensitive to NO, but the presence of O2 interferes with the NO measurement. Nitrogen gas in cylinders as sample gas was mixed with NO standard gas and/or O2 standard gas, and then introduced into the API-MS. The calibration curves of NO and O2 has linearity in the region of 0 - 2 ppm, but the slopes changed with every cylinder. The effect of O2 on NO+ peak was additive and proportional to O2 concentration in the range of 0 - 0.5 ppm. The increase in NO+ intensity due to O2 was (0.07 - 0.13)%/O2, 1 ppm. Determination of NO and O2 was carried out by the standard addition method to eliminate the influence of variation of slopes. The interference due to O2 was estimated from the product of the O2 concentration and the ratio of slope A to Slope B. Slope A is the change in the NO+ intensity with the O2 concentration. Slope B is the intensity with O2 concentration.

  3. High-ionization Gas in Active Galactic Nuclei: Line Profiles and Physical Conditions

    NASA Astrophysics Data System (ADS)

    Rodíguez-Ardila, A.; Riffel, R.; Mazzalay, X.; Portilla, J. G.

    2012-08-01

    SOAR/Goodman spectroscopy is employed to detect the coronal lines [Fe VII] 3759, 5159, and 6087 Å, [Ne V] 3423 Å and [Fe X] 6083 Å, the former three suitable to determine the temperature and density of the high-ionization gas. The spectra allow us to fully characterize the profiles of the most conspicuous lines (asymmetries, shifts from the centroid position and line width). The combined results allow us to detect signatures of outflows in the coronal gas and thus set up constrains on the origin of the CLs in AGNs. In addition, AO GEMINI/NIFS IFU spectroscopy is used to study the coronal gas morphology at spatial scales of a few parsecs in the Seyfert 2 galaxy NGC 1068. We found that the gas distribution is rather inhomogeneous and asymmetric. From the comparison of the CL [Mg VIII] with the VLA 6 cm radio emission we found evidence that the CL gas kinematics and morphology is strongly related to the radio jet morphology. All above results allow us to confirm the role that coronal lines have to trace outflows at the inner tens of parsecs of AGNs.

  4. Ionization effects in the generation of wake-fields by ultra-high contrast femtosecond laser pulses in argon gas

    SciTech Connect

    Makito, K.; Shin, J.-H.; Zhidkov, A.; Hosokai, T.; Masuda, S.; Kodama, R.

    2012-10-15

    Difference in mechanisms of wake-field generation and electron self-injection by high contrast femtosecond laser pulses in an initially neutral Argon gas and in pre-ionized plasma without ionization is studied via 2D particle-in-cell simulations including optical ionization of the media. For shorter laser pulses, 40 fs, ionization results only in an increase of the charge of accelerated electrons by factor of {approx}3 with qualitatively the same energy distribution. For longer pulses, 80 fs, a more stable wake field structure is observed in the neutral gas with the maximal energy of the accelerated electrons exceeding that in the fixed density plasma. In higher density Argon, an ionizing laser pulse converts itself to a complex system of solitons at a self-induced, critical density ramp.

  5. High resolution gas ionization chamber in proportional mode for low energy applications

    NASA Astrophysics Data System (ADS)

    Müller, Arnold Milenko; Döbeli, Max; Synal, Hans-Arno

    2017-09-01

    The operation of the ETH gas ionization detector as a proportional chamber, where a secondary ionization avalanche is initiated between the Frisch grid and anode, was investigated for ions covering the mass range from H to 127I. By amplifying the detector electron signal through secondary ionization, the limitations due to the sensitivity of the detector electronics are minimized. It could be demonstrated that in the energy range of a few hundreds of keV and below a proportional chamber clearly outperforms a conventionally used gas ionization detector. Protons below 10 keV were measured with a resolution better than 1.4 keV and a good linearity of the particle energy and detector signal was found in the energy range between 50 and 1000 keV. At higher energies almost no difference in resolution for the two operation modes could be found.

  6. Ionization-based detectors for gas chromatography.

    PubMed

    Poole, Colin F

    2015-11-20

    The gas phase ionization detectors are the most widely used detectors for gas chromatography. The column and makeup gases commonly used in gas chromatography are near perfect insulators. This facilitates the detection of a minute number of charge carriers facilitating the use of ionization mechanisms of low efficiency while providing high sensitivity. The main ionization mechanism discussed in this report are combustion in a hydrogen diffusion flame (flame ionization detector), surface ionization in a plasma (thermionic ionization detector), photon ionization (photoionization detector and pulsed discharge helium ionization detector), attachment of thermal electrons (electron-capture detector), and ionization by collision with metastable helium species (helium ionization detector). The design, response characteristics, response mechanism, and suitability for fast gas chromatography are the main features summarized in this report. Mass spectrometric detection and atomic emission detection, which could be considered as ionization detectors of a more sophisticated and complex design, are not discussed in this report. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Gas amplified ionization detector for gas chromatography

    DOEpatents

    Huston, Gregg C.

    1992-01-01

    A gas-amplified ionization detector for gas chromatrography which possesses increased sensitivity and a very fast response time. Solutes eluding from a gas chromatographic column are ionized by UV photoionization of matter eluting therefrom. The detector is capable of generating easily measured voltage signals by gas amplification/multiplication of electron products resulting from the UV photoionization of at least a portion of each solute passing through the detector.

  8. The Connection Between Reddening, Gas Covering Fraction, and the Escape of Ionizing Radiation at High Redshift

    NASA Astrophysics Data System (ADS)

    Reddy, Naveen A.; Steidel, Charles C.; Pettini, Max; Bogosavljević, Milan; Shapley, Alice E.

    2016-09-01

    Using a large sample of spectroscopically confirmed z∼ 3 galaxies, we establish an empirical relationship between reddening (E(B-V)), neutral gas covering fraction ({f}{{cov}}({{H}} {{I}})), and the escape of ionizing (Lyman continuum, LyC) photons. Our sample includes 933 galaxies at z∼ 3,121 of which have deep spectroscopic observations (≳ 7 hr) at 850≲ {λ }{{rest}}≲ 1300 Å with the Low Resolution Imaging Spectrograph on Keck. The high covering fraction of outflowing optically thick {{H}} {{I}} indicated by the composite spectra of these galaxies implies that photoelectric absorption, rather than dust attenuation, dominates the depletion of LyC photons. By modeling the composite spectra as the combination of an unattenuated stellar spectrum including nebular continuum emission with one that is absorbed by {{H}} {{I}} and reddened by a line-of-sight extinction, we derive an empirical relationship between E(B-V) and {f}{{cov}}({{H}} {{I}}). Galaxies with redder UV continua have larger covering fractions of {{H}} {{I}} characterized by higher line-of-sight extinctions. We develop a model which connects the ionizing escape fraction with E(B-V), and which may be used to estimate the ionizing escape fraction for an ensemble of galaxies. Alternatively, direct measurements of the escape fraction for our sample allow us to constrain the intrinsic LyC-to-UV flux density ratio to be < S(900 \\mathring{{A}} )/S(1500 \\mathring{{A}} ){> }{{int}}≳ 0.20, a value that favors stellar population models that include weaker stellar winds, a flatter initial mass function, and/or binary evolution. Last, we demonstrate how the framework discussed here may be used to assess the pathways by which ionizing radiation escapes from high-redshift galaxies. Based on data obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous

  9. The Properties and the Evolution of the Highly Ionized Gas in MR 2251-178

    NASA Technical Reports Server (NTRS)

    Kaspi, Shai; Netzer, hagai; Chelouche, Doron; George, Ian M.; Nandra, Kirpal; Turner, T. J.

    2004-01-01

    We present the first XMM-Newton observations of the radio-quiet quasar MR 2251-178 obtained in 2000 and 2002. The EPIC-pn spectra show a power-law continuum with a slope of Gamma = 1.6 at high energies absorbed by at least two warm absorbers (WAs) intrinsic to the source. The underlying continuum in the earlier observation shows a soft excess at low X-ray energies which can be modeled as an additional power-law with Gamma = 2.9. The spectra also show a weak narrow iron K alpha emission line. The high-resolution grating spectrum obtained in 2002 shows emission lines from N VI, O VII, O VIII, Ne IX, and Ne X, as well as absorption lines from the low-ionization ions of O III, O IV, and O V, and other confirmed and suspected weaker absorption lines. The O III - O V lines are consistent with the properties of the emission line gas observed as extended optical (O III) emission in this source. The signal-to-noise of the 2000 grating data is too low to detect any lines. We suggest a model for the high-resolution spectrum which consist of two or three warm-absorber (WA) components. The two-components model has a high-ionization WA with a column density of 10(exp 21.5)-10 (exp 21.8) sq cm and a low-ionization absorber with a column density of 10(exp 20.3) sq cm. In the three-components model we add a lower ionization component that produces the observed iron M-shell absorption lines. We investigate the spectral variations in MR 2251-178 over a period of 8.5 years using data from ASCA, BeppoSAX, and XMM-Newton. All X-ray observations can be fitted with the above two power laws and the two absorbers. The observed luminosity variations seems to correlate with variations in the soft X-ray continuum. The 8.5 year history of the source suggests a changing X-ray absorber due to material that enters and disappears from the line-of-sight on timescales of several months. We also present, for the first time, the entire FUSE spectrum of MR 2251-178. We detect emission from N III, C III

  10. High S/N Observations of Low-Ionization Gas Through the Galactic Halo

    NASA Astrophysics Data System (ADS)

    Meyer, D. M.; Roth, K. C.; Savage, B. D.; Lu, L.

    1993-12-01

    Optical absorption-line studies of extragalactic objects can now provide a sensitive probe of low-ionization gas over the full extent of the Galactic halo. Such work is particularly pertinent to a better understanding of the distances, metallicities, and sky coverage of the high-velocity clouds (HVCs) primarily observed in H I 21 cm emission. We have recently obtained high S/N, high resolution (20 km s(-1) ) KPNO 4-m echelle observations of the Ca II absorption toward the QSO 1821+643, the Seyfert galaxy Mkn 231, and SN 1993J in the galaxy M81. We detect a weak (W_lambda ~30 m Angstroms) Ca II component at an LSR velocity of -140 km s(-1) toward 1821+643 that corresponds to the Outer Arm H I HVC Complex. In the case of Mkn 231, we find no evidence of high-velocity Ca II absorption despite the location of this sightline near H I HVC Complex C. Our Ca II observations toward SN 1993J are especially exceptional in quality (S/N~500) and reveal absorption due to the Galactic halo, the disk of M81, and intergalactic material in the M81 group. Although the M81 disk gas dominates the absorption in the velocity region encompassing HVC Complex C, we do find a high-velocity component at +228 km s(-1) in Ca II that has also been seen in Mg II absorption with HST (Bowen et al. 1994, Ap. J. (Letters), in press). Our echelle spectra of SN 1993J also reveal detections of other interstellar atoms and molecules such as Ti II, Ca I, and CH(+) \\@. The Ti II measurement is particularly interesting in that it represents the first detection of Ti II toward an extragalactic object and indicates a Ti II scale height of about 1200 pc which is somewhat less than expected from observations of Ti II toward halo stars.

  11. FUSE and STIS Observations of Highly Ionized Gas along the Line of Sight towards HD 116852

    NASA Astrophysics Data System (ADS)

    Fox, A. J.; Savage, B. D.; Fabian, D.; Richter, P.; Sembach, K. R.; Meyer, D. M.; Lauroesch, J.; Howk, J. C.

    2002-05-01

    We present Space Telescope Imaging Spectrograph (STIS) and Far-Ultraviolet Spectroscopic Explorer (FUSE) observations of high ion interstellar ultraviolet absorption along the sight line to HD 116852. At a distance of 4.8 kpc, HD 116852 is an O9 III star lying in the low Galactic halo, -1.3 kpc from the plane of the Galaxy in the direction l = 304.9o, b = -6.1o. The sight line passes underneath the Sagittarius-Carina and the Norma-Centaurus spiral arms. The STIS E140H grating observations provide high-resolution (FWHM ≈ 2.7 km s-1) spectra of the resonance doublets of Si 4, C 4 and N 5. These data are complemented by medium-resolution (FWHM ≈ 20 km s-1) FUSE spectra of O 6. We find evidence for three distinct types of absorbing gas present in the data. First, two narrow absorption components are resolved in the Si 4 and \\ion {C}{4} profiles, at approximate LSR velocities of -36 and -10 km s-1. These narrow components appear to be produced in gas associated with the Norma and Sagittarius spiral arms, at approximate z-distances of -1.0 and -0.5 kpc respectively. The temperature of the gas in in these narrow components, as implied by their b-values, suggests that the gas is photoionized. The ratio of C 4 to Si 4 in these narrow components is low compared to the Galactic average. Second, we detect an intermediate-width component in C 4 and Si 4, at +17 km s-1, which we propose could arise at the conductive interface at the boundary between a dense cloud and the surrounding medium. Finally, a broad collisionally ionized component of gas responsible for producing the smooth N 5 and O 6 profiles is observed; such absorption is also present to a lesser degree in the profiles of Si 4 and \\ion {C}{4}. The broad O 6 absorption is observed at a velocity displaced from the C 4 profile by almost 20 km s-1, an amount large enough to suggest that the two ions may not co-exist in the same physical location. If these two ions do exist together, then the ratio N(C 4)/N(O 6) is

  12. Probing Conditions at Ionized/Molecular Gas Interfaces With High Resolution Near-Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Kaplan, Kyle Franklin

    2017-08-01

    Regions of star formation and star death in our Galaxy trace the cycle of gas and dust in the interstellar medium (ISM). Gas in dense molecular clouds collapses to form stars, and stars at the end of their lives return the gas that made up their outer layers back out into the Galaxy. Hot stars generate copious amounts of ultraviolet photons which interact with the surrounding medium and dominate the energetics, ionization state, and chemistry of the gas. The interface where molecular gas is being dissociated into neutral atomic gas by far-UV photons from a nearby hot source is called a photodissociation or photon-dominated region (PDR). PDRs are found primarily in star forming regions where O and B stars serve as the source of UV photons, and in planetary nebulae where the hot core of the dying star acts as the UV source. The main target of this dissertation is molecular hydrogen (H2), the most abundant molecule in the Universe, made from hydrogen formed during the Big Bang. H2 makes up the overwhelming majority of molecules found in the ISM and in PDRs. Far-UV radiation absorbed by H2 will excite an electron in the molecule. The molecule then either dissociates ( 10% of the time; Field et al. 1966) or decays into excited rotational and vibrational ("rovibrational") levels of the electronic ground state. These excited rovibrational levels then decay via a radiative cascade to the ground rovibrational state (v = 0, J = 0), giving rise to a large number of transitions observable in emission from the mid-IR to the optical (Black & van Dishoeck, 1987). These transitions provide an excellent probe of the excitation and conditions within the gas. These transitions are also observed in warm H2, such as in shocks, where collisions excite H2 to higher rovibrational levels. High resolution near-infrared spectroscopy, with its ability to see through dust, and avoid telluric absorption and emission, serves as an effective tool to detect emission from ions, atoms, and molecules

  13. Ionized Gas Kinematics at High Resolution. IV. Star Formation and a Rotating Core in the Medusa (NGC 4194)

    NASA Astrophysics Data System (ADS)

    Beck, Sara C.; Lacy, John; Turner, Jean; Greathouse, Thomas; Neff, Susan

    2014-05-01

    NGC 4194 is a post-merger starburst known as The Medusa for its striking tidal features. We present here a detailed study of the structure and kinematics of ionized gas in the central 0.65 kpc of the Medusa. The data include radio continuum maps with resolution up to 0.''18 (35 pc) and a 12.8 μm [Ne II] data cube with spectral resolution ~4 km s-1: the first high-resolution, extinction-free observations of this remarkable object. The ionized gas has the kinematic signature of a core in solid-body rotation. The starburst has formed a complex of bright compact H II regions, probably excited by deeply embedded super star clusters, but none of these sources is a convincing candidate for a Galactic nucleus. The nuclei of the merger partners that created the Medusa have not yet been identified.

  14. Ionized Gas Kinematics at High Resolution. IV. Star Formation and a Rotating Core in the Medusa (NGC 4194)

    NASA Technical Reports Server (NTRS)

    Beck, Sara C.; Lacy, John; Neff, Susan Gale; Turner, Jean; Greathouse, Thomas; Neff, Susan

    2014-01-01

    NGC 4194 is a post-merger starburst known as The Medusa for its striking tidal features.We present here a detailed study of the structure and kinematics of ionized gas in the central 0.65 kpc of the Medusa. The data include radio continuum maps with resolution up to 0".18 (35 pc) and a 12.8 micron [Ne II] data cube with spectral resolution approx. 4 km/s: the first high-resolution, extinction-free observations of this remarkable object. The ionized gas has the kinematic signature of a core in solid-body rotation. The starburst has formed a complex of bright compact H II regions, probably excited by deeply embedded super star clusters, but none of these sources is a convincing candidate for a Galactic nucleus. The nuclei of the merger partners that created the Medusa have not yet been identified.

  15. Ionized gas kinematics at high resolution. IV. Star formation and a rotating core in the Medusa (NGC 4194)

    SciTech Connect

    Beck, Sara C.; Lacy, John; Turner, Jean; Greathouse, Thomas; Neff, Susan

    2014-05-20

    NGC 4194 is a post-merger starburst known as The Medusa for its striking tidal features. We present here a detailed study of the structure and kinematics of ionized gas in the central 0.65 kpc of the Medusa. The data include radio continuum maps with resolution up to 0.''18 (35 pc) and a 12.8 μm [Ne II] data cube with spectral resolution ∼4 km s{sup –1}: the first high-resolution, extinction-free observations of this remarkable object. The ionized gas has the kinematic signature of a core in solid-body rotation. The starburst has formed a complex of bright compact H II regions, probably excited by deeply embedded super star clusters, but none of these sources is a convincing candidate for a Galactic nucleus. The nuclei of the merger partners that created the Medusa have not yet been identified.

  16. Determination of stimulants using gas chromatography/high-resolution time-of-flight mass spectrometry and a soft ionization source.

    PubMed

    Lopez-Avila, Viorica; Cooley, James; Urdahl, Randall; Thevis, Mario

    2012-12-15

    The aim of this study was to investigate the mass spectral fragmentation of a small set of stimulants in a high-resolution time-of-flight mass spectrometer equipped with a soft ionization source using vacuum ultraviolet (VUV) photons emitted from different plasma gases. It was postulated that the use of a plasma gas such as Xe, which emits photons at a lower energy than Kr or Ar, would lead to softer ionization of the test compounds, and thus to less fragmentation. A set of nine stimulants: cocaine, codeine, nicotine, methadone, phenmetrazine, pentylenetetrazole, niketamide, fencamfamine, and caffeine, was analyzed by gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) in positive ion mode with this soft ionization source, using either Xe, Kr, or Ar as plasma gases. Working solutions of the test compounds at 0.1 to 100 ng/μL were used to establish instrument sensitivity and linearity. All test compounds, except methadone and pentylenetetrazole, exhibited strong molecular ions and no fragmentation with Xe-microplasma photoionization (MPPI). Methadone exhibited significant fragmentation not only with Xe, but also with Kr and Ar, and pentylenetetrazole could not be ionized with Xe, probably because its ionization energy is above 8.44 eV. The Kr- and Ar-MPPI mass spectra of the test compounds showed that the relative intensity of the molecular ion decreased as the photon energy increased. When coupled to a TOF mass spectrometer this soft ionization source has demonstrated signal-to-noise (S/N) ratios from 7 to 730 at 100 pg per injection (depending on the compound), and a dynamic range of three orders of magnitude (100 pg to 100 ng) for some of the test compounds. Copyright © 2012 John Wiley & Sons, Ltd.

  17. Highly ionized gas absorption in the disk and halo toward HD 167756 at 3.5 kilometers per second resolution

    NASA Technical Reports Server (NTRS)

    Savage, Blair D.; Sembach, Kenneth R.; Cardelli, Jason A.

    1994-01-01

    High-resolution spectra of interstellar Si IV, C IV, and N V absorption lines along the 4 kpc path to the inner Galaxy star HD 167756 at z = -0.85 kpc are presented. The spectra were obtained with the echelle mode of Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope (HST) and have signal-to-noise ratios ranging from 23 to 38. The high resolution of the measurements full width at half maximum (FWHM = 3.5 km/s) results in fully resolved line profiles for the highly ionized gas absorption. The measurements provide information on the column density per unit velocity, N(v), as a function of velocity for Si IV, C IV, and N V. The C IV and N V profiles extend from -70 to +70 km/s, while the Si IV profiles extend from -40 to +70 km/s. The integrated logarithmic column densities are long N(Si IV) = 13.09 +/- 0.02, log N(C IV) = 13.83 +/- 0.02, and log N(N V) = 13.56 +/- 0.03. The N V profile is broad, asymmetric, and featureless, while the Si IV profile contains narrow absorption components near V(sub LSR) = -19, 0, +20, and +52 km/s with Doppler spread parameters, b about = 10-12 km/s. The C IV profile contains both broad and narrow structure. The high ion feature near +52 km/s is also detected in the low-ionization lines of Ca II, O I, Si II, and Fe II. The other narrow Si IV and C IV components occur within several km/s of components seen in low-ionization species. The sight line contains at least two types of highly ionized gas. One type gives rise to a broad N V profile, and the other results in the more structured Si IV profile. The C IV profile contains contributions from both types of highly ionized gas. The broad but asymmetric N V profile is well represented by a large Galactic scale height gas which is participating in Galactic rotation and has a combination of thermal and turbulent broadening with b(sub tot) about = 42 km/s. The C IV to N V abundance ratio of 1.0 +/- 0.3 for the gas implies T about 1.6 x 10(exp 5) K or about 8 x 10

  18. Present-day Galactic Evolution: Low-metallicity, Warm, Ionized Gas Inflow Associated with High-velocity Cloud Complex A

    NASA Astrophysics Data System (ADS)

    Barger, K. A.; Haffner, L. M.; Wakker, B. P.; Hill, Alex. S.; Madsen, G. J.; Duncan, A. K.

    2012-12-01

    The high-velocity cloud Complex A is a probe of the physical conditions in the Galactic halo. The kinematics, morphology, distance, and metallicity of Complex A indicate that it represents new material that is accreting onto the Galaxy. We present Wisconsin Hα Mapper kinematically resolved observations of Complex A over the velocity range of -250 to -50 km s-1 in the local standard of rest reference frame. These observations include the first full Hα intensity map of Complex A across (\\mathit {l, b}) = (124{^\\circ }, 18{^\\circ }) to (171°, 53°) and deep targeted observations in Hα, [S II] λ6716, [N II] λ6584, and [O I] λ6300 toward regions with high H I column densities, background quasars, and stars. The Hα data imply that the masses of neutral and ionized material in the cloud are similar, both being greater than 106 M ⊙. We find that the Bland-Hawthorn & Maloney model for the intensity of the ionizing radiation near the Milky Way is consistent with the known distance of the high-latitude part of Complex A and an assumed cloud geometry that puts the lower-latitude parts of the cloud at a distance of 7-8 kpc. This compatibility implies a 5% ionizing photon escape fraction from the Galactic disk. We also provide the nitrogen and sulfur upper abundance solutions for a series of temperatures, metallicities, and cloud configurations for purely photoionized gas; these solutions are consistent with the sub-solar abundances found by previous studies, especially for temperatures above 104 K or for gas with a high fraction of singly ionized nitrogen and sulfur.

  19. Terahertz ionization of highly charged quantum posts in a perforated electron gas.

    PubMed

    Morris, Christopher M; Stehr, Dominik; Kim, Hyochul; Truong, Tuan-Anh; Pryor, Craig; Petroff, Pierre M; Sherwin, Mark S

    2012-03-14

    "Quantum posts" are roughly cylindrical semiconductor nanostructures that are embedded in an energetically shallower "matrix" quantum well of comparable thickness. We report measurements of voltage-controlled charging and terahertz absorption of 30 nm thick InGaAs quantum wells and posts. Under flat-band (zero-electric field) conditions, the quantum posts each contain approximately six electrons, and an additional ~2.4 × 10(11) cm(-2) electrons populate the quantum well matrix. In this regime, absorption spectra show peaks at 3.5 and 4.8 THz (14 and 19 meV) whose relative amplitude depends strongly on temperature. These peaks are assigned to intersubband transitions of electrons in the quantum well matrix. A third, broader feature has a temperature-independent amplitude and is assigned to an absorption involving quantum posts. Eight-band k·p calculations incorporating the effects of strain and Coulomb repulsion predict that the electrons in the posts strongly repel the electrons in the quantum well matrix, "perforating" the electron gas. The strongest calculated transition, which has a frequency close to the center of the quantum post related absorption at 5 THz (20 meV), is an ionizing transition from a filled state to a quasi-bound state that can easily scatter to empty states in the quantum well matrix. © 2011 American Chemical Society

  20. Double ionization effect in electron accelerations by high-intensity laser pulse interaction with a neutral gas

    NASA Astrophysics Data System (ADS)

    Nandan Gupta, Devki

    2013-11-01

    We study the effect of laser-induced double-ionization of a helium gas (with inhomogeneous density profile) on vacuum electron acceleration. For enough laser intensity, helium gas can be found doubly ionized and it strengthens the divergence of the pulse. The double ionization of helium gas can defocus the laser pulse significantly, and electrons are accelerated by the front of the laser pulse in vacuum and then decelerated by the defocused trail part of the laser pulse. It is observed that the electrons experience a very low laser-intensity at the trailing part of the laser pulse. Hence, there is not much electron deceleration at the trailing part of the pulse. We found that the inhomogeneity of the neutral gas reduced the rate of tunnel ionization causing less defocusing of the laser pulse and thus the electron energy gain is reduced.

  1. Highly ionized gas in the Gum nebula and elsewhere - A comparison of IUE and Copernicus satellite results

    NASA Technical Reports Server (NTRS)

    Edgar, Richard J.; Savage, Blair D.

    1992-01-01

    The data from six high-dispersion IUE echelle spectra are averaged in order to obtain an interstellar absorption line spectrum with an S/N of about 30 and a resolution of about 25 km/s. The interstellar lines of C IV and Si IV are very strong and broad and N V is detected. The profiles for these species and Al III are compared to the Copernicus satellite profiles for O VI. The high ionization lines toward HD 64760 are much stronger and broader than those recorded toward Zeta Pup and Gamma super 2 Vel, the two exciting stars of the Gum nebula. The profiles for Al III and Si IV are similar and considerably narrower than the O VI profile. An origin in photoionized Gum nebula gas is suggested as the most likely explanation for Al III and Si IV. The C IV profile has a high positive velocity wing extending to approximately +80 km/s, which is similar in appearance to the positive velocity portion of the O VI profile. It is inferred that a substantial part of the observed C IV has an origin in the collisionally ionized gas most likely rsponsible for the O VI.

  2. Highly ionized gas in the Gum nebula and elsewhere - A comparison of IUE and Copernicus satellite results

    NASA Technical Reports Server (NTRS)

    Edgar, Richard J.; Savage, Blair D.

    1992-01-01

    The data from six high-dispersion IUE echelle spectra are averaged in order to obtain an interstellar absorption line spectrum with an S/N of about 30 and a resolution of about 25 km/s. The interstellar lines of C IV and Si IV are very strong and broad and N V is detected. The profiles for these species and Al III are compared to the Copernicus satellite profiles for O VI. The high ionization lines toward HD 64760 are much stronger and broader than those recorded toward Zeta Pup and Gamma super 2 Vel, the two exciting stars of the Gum nebula. The profiles for Al III and Si IV are similar and considerably narrower than the O VI profile. An origin in photoionized Gum nebula gas is suggested as the most likely explanation for Al III and Si IV. The C IV profile has a high positive velocity wing extending to approximately +80 km/s, which is similar in appearance to the positive velocity portion of the O VI profile. It is inferred that a substantial part of the observed C IV has an origin in the collisionally ionized gas most likely rsponsible for the O VI.

  3. VizieR Online Data Catalog: Properties of the highly ionized gas of quasars (Lehner+, 2014)

    NASA Astrophysics Data System (ADS)

    Lehner, N.; O'Meara, J. M.; Fox, A. J.; Howk, J. C.; Prochaska, J. X.; Burns, V.; Armstrong, A. A.

    2017-07-01

    All data in this sample were acquired with the HIgh Resolution Echelle Spectrometer (HIRES; Vogt et al. 1994SPIE.2198..362V) on the Keck I telescope on Mauna Kea. These data were obtained by different PIs from different institutions with Keck access, and hundreds of spectra of QSOs at 0high-z QSO spectra at high spectral resolution (6-8 km/s) and high signal-to-noise (many with S/N>20-50). We were awarded a NASA Astrophysics Data Analysis Program (ADAP) grant (PI Lehner) to perform the data reduction and coaddition of the individual exposures of the entire KOA QSO database to study in detail the highly ionized plasma associated with {tau}LL>1 absorbers at 2

  4. Miniaturized gas ionization sensors using carbon nanotubes.

    PubMed

    Modi, Ashish; Koratkar, Nikhil; Lass, Eric; Wei, Bingqing; Ajayan, Pulickel M

    2003-07-10

    Gas sensors operate by a variety of fundamentally different mechanisms. Ionization sensors work by fingerprinting the ionization characteristics of distinct gases, but they are limited by their huge, bulky architecture, high power consumption and risky high-voltage operation. Here we report the fabrication and successful testing of ionization microsensors featuring the electrical breakdown of a range of gases and gas mixtures at carbon nanotube tips. The sharp tips of nanotubes generate very high electric fields at relatively low voltages, lowering breakdown voltages several-fold in comparison to traditional electrodes, and thereby enabling compact, battery-powered and safe operation of such sensors. The sensors show good sensitivity and selectivity, and are unaffected by extraneous factors such as temperature, humidity, and gas flow. As such, the devices offer several practical advantages over previously reported nanotube sensor systems. The simple, low-cost, sensors described here could be deployed for a variety of applications, such as environmental monitoring, sensing in chemical processing plants, and gas detection for counter-terrorism.

  5. Miniaturized gas ionization sensors using carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Modi, Ashish; Koratkar, Nikhil; Lass, Eric; Wei, Bingqing; Ajayan, Pulickel M.

    2003-07-01

    Gas sensors operate by a variety of fundamentally different mechanisms. Ionization sensors work by fingerprinting the ionization characteristics of distinct gases, but they are limited by their huge, bulky architecture, high power consumption and risky high-voltage operation. Here we report the fabrication and successful testing of ionization microsensors featuring the electrical breakdown of a range of gases and gas mixtures at carbon nanotube tips. The sharp tips of nanotubes generate very high electric fields at relatively low voltages, lowering breakdown voltages several-fold in comparison to traditional electrodes, and thereby enabling compact, battery-powered and safe operation of such sensors. The sensors show good sensitivity and selectivity, and are unaffected by extraneous factors such as temperature, humidity, and gas flow. As such, the devices offer several practical advantages over previously reported nanotube sensor systems. The simple, low-cost, sensors described here could be deployed for a variety of applications, such as environmental monitoring, sensing in chemical processing plants, and gas detection for counter-terrorism.

  6. Turbulence and the ionization of interstellar gas

    NASA Astrophysics Data System (ADS)

    Hill, Alex S.

    2015-08-01

    Turbulence is widely observed in the ionized gas in the interstellar media of star-forming galaxies. Observations in the Milky Way indicate emission from that the warm ionized medium -- ionized gas far from massive stars, the most likely source of the ionization -- has a lognormal intensity distribution. This and other measurements indicate that the gas is well-described as a transonic turbulent fluid. Such a fluid can be produced by feedback from supernovae in the Galaxy. Understanding of this turbulence has also led to a natural explanation for a long-standing puzzle: how do ionizing photons travel through the largely-neutral interstellar medium and produce the ionization? In the turbulent gas, low-density pathways allow ionizing photons to propagate for kiloparsecs, with implications for radiative energy transport in star-forming galaxies.

  7. Ionization in nearby interstellar gas

    NASA Technical Reports Server (NTRS)

    Frisch, P. C.; Welty, D. E.; York, D. G.; Fowler, J. R.

    1990-01-01

    Due to dielectric recombination, neutral magnesium represents an important tracer for the warm low-density gas around the solar system. New Mg I 2852 absorption-line data from IUE are presented, including detections in a few stars within 40 pc of the sun. The absence of detectable Mg I in Alpha CMa and other stars sets limits on the combined size and electron density of the interstellar cloud which gives rise to the local interstellar wind. For a cloud radius greater than 1 pc and density of 0.1/cu cm, the local cloud has a low fractional ionization, n(e)/n(tot) less than 0.05, if magnesium is undepleted, equilibrium conditions prevail, the cloud temperature is 11,750 K, and 80 percent of the magnesium in the sightline is Mg II.

  8. Dust and Ionized Gas in Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Goudfrooij, Paul

    1995-05-01

    stellar component in the centre (assuming trailing spiral arms). These findings are clear signatures of an acquisition of a companion galaxy. The radial emission-line intensity profile peaks much more strongly towards the centre than the stellar light profile does, suggesting a powerful nuclear ionization source. In Chapter 2 we present deep surface photometry of NGC 1275, the central dominant galaxy of the Perseus cluster. This peculiar galaxy features two distinct filamentary systems, 3000 km s^-1 apart in velocity space. The "host"-galaxy NGC 1275 is associated with the low-velocity system, whereas the nature of the high-velocity system is still controversial. We find that prominent dust absorption features of NGC 1275 have the same distribution on the sky as the high-velocity system of ionized gas. Hence, the dust patches are most probably associated with the high-velocity system. However, our analysis of the extinction properties of the dust patches shows that the dust is well within NGC 1275, implying that the high-velocity system has moved approximately halfway through NGC 1275. We have also found many blue star clusters in our images of NGC 1275, for which we discuss the origin and nature by comparing colour-magnitude diagrams with theoretical population models. We suggest that the blue star clusters have been formed in a cooling flow in the central part of the X-ray-emitting gas of the Perseus cluster of galaxies. Chapter 3 presents the CCD broad-band photometry of the sample ellipticals. Radial profiles of the surface brightness, colours, and characteristics of the detailed isophotal shape are derived. In addition, we show that fitting power-laws to the outer radial intensity profiles of elliptical galaxies is an excellent tool for determining the sky background for CCD photometry. Chapter 4 presents colour-index images and narrow-band images of the H-alpha+[N II]-emitting gas to derive the distribution and amount of dust and ionized gas for the sample

  9. Enhanced Stability of Electrohydrodynamic Jets through Gas Ionization

    NASA Astrophysics Data System (ADS)

    Korkut, Sibel; Saville, Dudley A.; Aksay, Ilhan A.

    2008-01-01

    Theoretical predictions of the nonaxisymmetric instability growth rate of an electrohydrodynamic jet based on the measured total current overestimate experimental values. We show that this apparent discrepancy is the result of gas ionization in the surrounding gas and its effect on the surface charge density of the jet. As a result of gas ionization, a sudden drop in the instability growth rate occurs below a critical electrode separation, yielding highly stable jets that can be used for nano- to microscale printing.

  10. Enhanced stability of electrohydrodynamic jets through gas ionization.

    PubMed

    Korkut, Sibel; Saville, Dudley A; Aksay, Ilhan A

    2008-01-25

    Theoretical predictions of the nonaxisymmetric instability growth rate of an electrohydrodynamic jet based on the measured total current overestimate experimental values. We show that this apparent discrepancy is the result of gas ionization in the surrounding gas and its effect on the surface charge density of the jet. As a result of gas ionization, a sudden drop in the instability growth rate occurs below a critical electrode separation, yielding highly stable jets that can be used for nano- to microscale printing.

  11. Highly-Ionized Gas in the Galactic Halo: A FUSE Survey of O 6 Absorption toward 22 Halo Stars

    NASA Astrophysics Data System (ADS)

    Zsargo, J.; Sembach, K. R.; Howk, J. C.; Savage, B. D.

    2002-12-01

    Far Ultraviolet Spectroscopic Explorer (FUSE) spectra of 22 Galactic halo stars are studied to determine the amount of O 6 in the Galactic halo between ~0.3 and ~10 kpc from the Galactic mid-plane. Strong O 6 λ 1031.93 absorption was detected toward 21 stars, and a reliable 3 σ upper limit was obtained toward HD 97991. The weaker member of the O 6 doublet at 1037.62 Å could be studied toward only six stars. The observed columns are reasonably consistent with a patchy exponential O 6 distribution with a mid-plane density of 1.7x10-8 cm-3 and scale height between 2.3 and 4 kpc. We do not see clear signs of strong high-velocity components in O 6 absorption along the Galactic sight lines, which indicates the general absence of high velocity O 6 within 2-5 kpc of the Galactic mid-plane. The correlation between the H 1 and O 6 intermediate velocity absorption is also poor. The O 6 velocity dispersions are much larger than the value of ~18 km/s expected from thermal broadening for gas at T ~ 3x105 K, the temperature at which O 6 is expected to reach its peak abundance in collisional ionization equilibrium. Turbulence, inflow, and outflow must have an effect on the shape of the O 6 profiles. Kinematical comparisons of O 6 with Ar 1 reveal that 9 of 21 sight lines are closely aligned in LSR velocity (|Δ VLSR| <=5 km/s ), while 8 of 21 exhibit significant velocity differences (|Δ VLSR| >= 15 km/s ). This dual behavior may indicate the presence of two different types of O 6-bearing environments toward the Galactic sight lines. Comparison of O 6 with other highly-ionized species suggests that the high ions are produced primarily by cooling hot gas in the Galactic fountain flow, and that turbulent mixing also has a significant contribution. The role of turbulent mixing is most important toward sight lines that sample supernova remnants like Loop I and IV. We are also able to show that the O 6 enhancement toward the Galactic center region that was observed in the FUSE

  12. Coupling of gas chromatography and electrospray ionization high resolution mass spectrometry for the analysis of anabolic steroids as trimethylsilyl derivatives in human urine.

    PubMed

    Cha, Eunju; Jeong, Eun Sook; Cha, Sangwon; Lee, Jaeick

    2017-04-29

    In this study, gas chromatography (GC) was interfaced with high resolution mass spectrometry (HRMS) with electrospray ionization source (ESI) and the relevant parameters were investigated to enhance the ionization efficiency. In GC-ESI, the distances (x-, y- and z) and angle between the ESI needle, GC capillary column and MS orifice were set to 7 (x-distance), 4 (y-distance), and 1 mm (z-distance). The ESI spray solvent, acid modifier and nebulizer gas flow were methanol, 0.1% formic acid and 5 arbitrary units, respectively. Based on these results, analytical conditions for GC-ESI/HRMS were established. In particular, the results of spray solvent flow indicated a concentration-dependent mechanism (peak dilution effect), and other parameters also greatly influenced the ionization performance. The developed GC-ESI/HRMS was then applied to the analysis of anabolic steroids as trimethylsilyl (TMS) derivatives in human urine to demonstrate its application. The ionization profiles of TMS-derivatized steroids were investigated and compared with those of underivatized steroids obtained from gas chromatography-electrospray ionization/mass spectrometry (GC-ESI/MS) and liquid chromatography-electrospray ionization/mass spectrometry (LC-ESI/MS). The steroids exhibited ionization profiles based on their structural characteristics, regardless of the analyte phase or derivatization. Groups I and II with conjugated or unconjugated keto functional groups at C3 generated the [M+H](+) and [M+H-TMS](+) ions, respectively. On the other hand, Groups III and IV gave rise to the characteristic fragment ions [M+H-TMS-H2O](+) and [M+H-2TMS-H2O](+), corresponding to loss of a neutral TMS·H2O moiety from the protonated molecular ion by in-source dissociation. To the best of our knowledge, this is the first study to successfully ionize and analyze steroids as TMS derivatives using ESI coupled with GC. The present system has enabled the ionization of TMS derivatives under ESI conditions and

  13. IONIZED GAS KINEMATICS AT HIGH RESOLUTION. V. [Ne ii], MULTIPLE CLUSTERS, HIGH EFFICIENCY STAR FORMATION, AND BLUE FLOWS IN HE 2–10

    SciTech Connect

    Beck, Sara; Turner, Jean; Lacy, John; Greathouse, Thomas

    2015-11-20

    We measured the 12.8 μm [Ne ii] line in the dwarf starburst galaxy He 2–10 with the high-resolution spectrometer TEXES on the NASA IRTF. The data cube has a diffraction-limited spatial resolution of ∼1″ and a total velocity resolution, including thermal broadening, of ∼5 km s{sup −1}. This makes it possible to compare the kinematics of individual star-forming clumps and molecular clouds in the three dimensions of space and velocity, and allows us to determine star formation efficiencies. The kinematics of the ionized gas confirm that the starburst contains multiple dense clusters. From the M/R of the clusters and the ≃30%–40% star formation efficiencies, the clusters are likely to be bound and long lived, like globulars. Non-gravitational features in the line profiles show how the ionized gas flows through the ambient molecular material, as well as a narrow velocity feature, which we identify with the interface of the H ii region and a cold dense clump. These data offer an unprecedented view of the interaction of embedded H ii regions with their environment.

  14. The distribution of warm ionized gas in NGC 891

    NASA Technical Reports Server (NTRS)

    Rand, Richard J.; Kulkarni, Shrinivas R.; Hester, J. Jeff

    1990-01-01

    Narrow-band imaging is presented of the edge-on spiral NGC 891 in the H-alpha and S II 6716, 6731 A forbidden lines. Emission from H II regions confined to the plane of the galaxy and from diffuse gas up to about 4 kpc off the plane is readily detected. The full radial extent of the diffuse emission in the plane is about 30 kpc. NGC 891 is found to have a surface density of diffuse ionized gas twice the Galactic value, a thicker ionized gas layer, and a larger surface density of ionized gas relative to neutral gas. These are interpreted as consequences of a relatively high level of star formation in this galaxy. Other star formation tracers indicate the same conclusion. Many vertical H-alpha filaments, or 'worms,' extending to over 2 kpc off the plane of the galaxy are seen. These worms are interpreted in terms of chimney models for the interstellar media of spirals.

  15. The Kinematics of the Ionized Gas in IC 10

    NASA Astrophysics Data System (ADS)

    Thurow, Joshua C.; Wilcots, Eric M.

    2005-02-01

    We present the results of a WIYN integral field unit study of the kinematics of the ionized gas in IC 10, a dwarf irregular starburst galaxy in the Local Group. Though the velocity field of the ionized gas closely matches that of the H I, there are several kinematically interesting features in the galaxy. The diffuse ionized gas in the galaxy exhibits larger Hα line widths than the bright complexes. In one case this is due to an infusion of energy into the gas associated with the radio superbubble discovered by Yang & Skillman. We find that the amount of energy in this region is consistent with their hypothesis that the region contains 10 supernova remnants. We also detect a high-velocity (70 km s-1) expanding shell in the ionized gas, which is likely driven by three confirmed Wolf-Rayet stars that are located within the shell. Extrapolating from Hunter's initial mass function, we find that the central starburst region contains approximately equal energy contributions from stellar winds and supernovae (SNe), suggesting that SNe are just beginning to play a significant role in shaping the kinematics of the ionized gas. However, all of this energy cannot be easily accounted for in the kinematics of the gas. We detect an energetic flow of gas (3×1052 ergs), which we believe originates from the starburst region. We also detect a high-velocity (70 km s-1) feature not coincident with any structure in our Hα image. This feature, along with the flow and shell, can account for the energy produced by stellar wind and SNe. The flow resembles one discovered by Wilcots & Thurow in NGC 4214; together they suggest that the porosity of the interstellar medium contributes significantly to the high velocity of some portion of the ionized gas in irregular galaxies.

  16. COMPLETE IONIZATION OF THE NEUTRAL GAS: WHY THERE ARE SO FEW DETECTIONS OF 21 cm HYDROGEN IN HIGH-REDSHIFT RADIO GALAXIES AND QUASARS

    SciTech Connect

    Curran, S. J.; Whiting, M. T.

    2012-11-10

    From the first published z {approx}> 3 survey of 21 cm absorption within the hosts of radio galaxies and quasars, Curran et al. found an apparent dearth of cool neutral gas at high redshift. From a detailed analysis of the photometry, each object is found to have a {lambda} = 1216 A continuum luminosity in excess of L {sub 1216} {approx} 10{sup 23} W Hz{sup -1}, a critical value above which 21 cm has never been detected at any redshift. At these wavelengths, and below, hydrogen is excited above the ground state so that it cannot absorb in 21 cm. In order to apply the equation of photoionization equilibrium, we demonstrate that this critical value also applies to the ionizing ({lambda} {<=} 912 A) radiation. We use this to show, for a variety of gas density distributions, that upon placing a quasar within a galaxy of gas, there is always an ultraviolet luminosity above which all of the large-scale atomic gas is ionized. While in this state, the hydrogen cannot be detected or engage in star formation. Applying the mean ionizing photon rate of all of the sources searched, we find, using canonical values for the gas density and recombination rate coefficient, that the observed critical luminosity gives a scale length (3 kpc) similar that of the neutral hydrogen (H I) in the Milky Way, a large spiral galaxy. Thus, this simple yet physically motivated model can explain the critical luminosity (L {sub 912} {approx} L {sub 1216} {approx} 10{sup 23} W Hz{sup -1}), above which neutral gas is not detected. This indicates that the non-detection of 21 cm absorption is not due to the sensitivity limits of current radio telescopes, but rather that the lines of sight to the quasars, and probably the bulk of the host galaxies, are devoid of neutral gas.

  17. Laboratory simulation of cometary neutral gas ionization

    NASA Technical Reports Server (NTRS)

    Chang, Tsuey-Fen; Rahman, H. U.; White, R. S.

    1989-01-01

    The laboratory simulation of the interaction of the solar wind with a comet is used to study the cometary neural gas ionization. The experiment is carried out in the UCR T-1 facility with an ice ball as the comet model. Photographs and data are taken with a variety of values of the solar wind velocity, interplanetary magnetic field (IMF), and comet configurations. The results show that the cometary neutral gas ionization depends on both the velocity of the solar wind and the interplanetary magnetic field. The plasma cloud surrounding the comet is visible only when the solar wind velocity and IMF are both above certain minimum values. This velocity dependent phenomena is explained by Alfven's critical ionization velocity effect. The critical magnetic field may be explained by assuming two stream lower hybrid instability as a triggering mechanism for the ionization of the neutral gas by plasma flow. Critical upper and lower limits for the magnetic field, required by anomalous ionization, are also derived that satisfy the experimental observations.

  18. Evaluation of gas chromatography - electron ionization - full scan high resolution Orbitrap mass spectrometry for pesticide residue analysis.

    PubMed

    Mol, Hans G J; Tienstra, Marc; Zomer, Paul

    2016-09-07

    Gas chromatography with electron ionization and full scan high resolution mass spectrometry with an Orbitrap mass analyzer (GC-EI-full scan Orbitrap HRMS) was evaluated for residue analysis. Pesticides in fruit and vegetables were taken as an example application. The relevant aspects for GC-MS based residue analysis, including the resolving power (15,000 to 120,000 FWHM at m/z 200), scan rate, dynamic range, selectivity, sensitivity, analyte identification, and utility of existing EI-libraries, are assessed and discussed in detail. The optimum acquisition conditions in full scan mode (m/z 50-500) were a resolving power of 60,000 and an automatic-gain-control target value of 3E6. These conditions provided (i) an optimum mass accuracy: within 2 ppm over a wide concentration range, with/without matrix, enabling the use of ±5 ppm mass extraction windows (ii) adequate scan speed: minimum 12 scans/peak, (iii) an intra-scan dynamic range sufficient to achieve LOD/LOQs ≤0.5 pg in fruit/vegetable matrices (corresponding to ≤0.5 μg kg(-1)) for most pesticides. EI-Orbitrap spectra were consistent over a very wide concentration range (5 orders) with good match values against NIST (EI-quadrupole) spectra. The applicability for quantitative residue analysis was verified by validation of 54 pesticides in three matrices (tomato, leek, orange) at 10 and 50 μg/kg. The method involved a QuEChERS-based extraction with a solvent switch into iso-octane, and 1 μL hot splitless injection into the GC-HRMS system. A recovery between 70 and 120% and a repeatability RSD <10% was obtained in most cases. Linearity was demonstrated for the range ≤5-250 μg kg(-1). The pesticides could be identified according to the applicable EU criteria for GC-HRMS (SANTE/11945/2015). GC-EI-full scan Orbitrap HRMS was found to be highly suited for quantitative pesticide residue analysis. The potential of qualitative screening to extend the scope makes it an attractive alternative to GC

  19. CO/H2, C/CO, OH/CO, and OH/O2 in dense interstellar gas: from high ionization to low metallicity

    NASA Astrophysics Data System (ADS)

    Bialy, Shmuel; Sternberg, Amiel

    2015-07-01

    We present numerical computations and analytic scaling relations for interstellar ion-molecule gas-phase chemistry down to very low metallicities (10-3 × solar), and/or up to high driving ionization rates. Relevant environments include the cool interstellar medium (ISM) in low-metallicity dwarf galaxies, early enriched clouds at the reionization and Pop-II star formation era, and in dense cold gas exposed to intense X-ray or cosmic ray sources. We focus on the behaviour for H2, CO, CH, OH, H2O and O2, at gas temperatures ˜100 K, characteristic of a cooled ISM at low metallicities. We consider shielded or partially shielded one-zone gas parcels, and solve the gas-phase chemical rate equations for the steady-state `metal-molecule abundances for a wide range of ionization parameters, ζ/n, and metallicties, Z '. We find that the OH abundances are always maximal near the H-to-H2 conversion points, and that large OH abundances persist at very low metallicities even when the hydrogen is predominantly atomic. We study the OH/O2, C/CO and OH/CO abundance ratios, from large to small, as functions of ζ/n and Z '. Much of the cold dense ISM for the Pop-II generation may have been OH-dominated and atomic rather than CO-dominated and molecular.

  20. Deposition profile of Ti film inside a trench and its correlation with gas-phase ionization in high-pressure magnetron sputtering

    SciTech Connect

    Nafarizal, N.; Takada, N.; Nakamura, K.; Sago, Y.; Sasaki, K.

    2006-11-15

    This article reports the relationship between the degree of ionization of Ti in the gas phase and the thickness profile of Ti film inside a trench in magnetron sputtering deposition. A conventional magnetron sputtering plasma source was used for depositing Ti films inside trenches formed on rf-biased SiO{sub 2} substrates. It was found that a high bottom coverage was obtained when a high gas pressure and a long distance between the target and the substrate were employed for the deposition. On the other hand, at a short distance between the target and the substrate, the bottom coverage was small and was almost independent of the gas pressure. The deposition profile was compared with the spatial distributions of Ti and Ti{sup +} densities measured by laser-induced fluorescence (LIF) imaging spectroscopy. The LIF results revealed that the density ratio of Ti{sup +} to Ti in the downstream region increased with the gas pressure up to 0.3, while in the upstream region, it was small (<0.05) and was roughly constant with the gas pressure. In the case with the enhanced density ratio of 0.3, the flux ratio of Ti{sup +} to Ti was estimated to be 4.4. Hence, it was concluded that, with a high gas pressure and a long distance between the target and substrate, the deposition profile with a high bottom coverage was obtained by accelerating Ti{sup +} toward the bottom of the trench. The high-pressure magnetron sputtering discharge is useful for enhancing the degree of ionization and the bottom coverage.

  1. The distribution of ionized gas in early-type galaxies

    NASA Astrophysics Data System (ADS)

    Buson, L. M.; Sadler, E. M.; Zeilinger, W. W.; Bertin, G.; Bertola, F.; Danzinger, J.; Dejonghe, H.; Saglia, R. P.; de Zeeuw, P. T.

    1993-12-01

    We present and discuss H-alpha+(N II) imaging observations of fifteen nearby elliptical and SO galaxies with extended optical emission lines. The morphology of the emitting regions suggests that the ionized gas usually lies in a disk which is often geometrically decoupled from the stellar body, as expected in a triaxial galaxy. The presence of a gaseous disk makes these galaxies suitable for testing their gravitational field in a straightforward way. The presence of dust in many of the disks, together with the observed morphological properties, suggests that the ionized gas in most of these galaxies is more closely associated with the cold Interstellar Medium (ISM) than with the hot X-ray component. The mass of ionized gas in the galaxies studied here is typically 10-100 times that in a 'normal' early-type galaxy of similar optical luminosity. These appear to be galaxies where an unusually high fraction of the cold gas has been ionized, rather than unusually gas-rich systems in an overall sense. The extra ionizing source may be related to an active nucleus, since the continuum radio emission from these galaxies is typically 10-15 times more powerful than in 'normal' ellipticals of the smae optical luminosity.

  2. Fabrication of a miniaturized ionization gas sensor with polyimide spacer

    NASA Astrophysics Data System (ADS)

    Walewyns, T.; Scheen, G.; Tooten, E.; El Fissi, L.; Dupuis, P.; Francis, L. A.

    2011-06-01

    Gas sensing can be achieved by fingerprinting the ionization characteristics of distinct species. In this study, the fabrication of a miniaturized gas ionization sensor using polyimide as sacrificial layer is reported. The sensor consists of two planar metallic electrodes with a gap spacing obtained by the polyimide under-etching. This known sacrificial layer has the advantage besides a high planarization factor, to be CMOS compatible. Furthermore, its chemical resistance up to high temperatures, high resistance to radiation from both electrons and neutrons, and low outgassing are of primary importance to avoid interferences with the ionization gas sensing. A suspended micro-bridge with dimensions 20 μm width and 220 μm length has been developed and released by using etching holes in the membrane. The ionization characteristics of air at controlled temperature, humidity and pressure (21°C, 40% humidity and 1 atm) have been obtained during non-destructive electrical characterizations, with a breakdown voltage of 350 V for a 6 μm gap. The growth of metallic nanowires templated in ion track-etched polyimide on the electrode is envisioned in order to enhance the ionization field and to reduce the required measurement power of the sensor.

  3. GAS IONIZING AND COMPRESSING DEVICE

    DOEpatents

    Little, E.M.; Thomson, D.B.; Josephson, V.; Scott, F.R.

    1961-08-22

    A device is described for producing high energy gaseous plasmas. The device consists of a unitary refractory vessel having tapered end portions, a cylindrical middle portion, and means for spontaneously generating oppositely propelled plasma masses from the tapered end portions to a collision zone in the cylindrical middle portion. The means come from the spontaneous generation of diverging magnetic fields in the end portions and an axial magnetic field in the cylindrical portion. (AEC)

  4. Gas-Liquid Correlation of Ionization Energies.

    DTIC Science & Technology

    1984-04-01

    ions and water. The threshold and reorganization energies of the hydrated electron are calculated from threshold energies of anions and their absorption...hydroxide ions and water. The threshold and reorganization energies of the hydrated electron are calculated from threshold energies of anions and their...threshold energy of the hydrated electron. 2. Free energy of emission and gas-phase ionization Consider the photoelectron emission by an aqueous

  5. The PRIME Lab gas ionization detector

    NASA Astrophysics Data System (ADS)

    Knies, David L.; Elmore, David

    1994-06-01

    A gas ionization detection system was built for optimal identification of AMS radionuclides, in particular 10Be and 36Cl. For 36Cl, a combination of 1) the difference in arrival times for electrons at two anode plates and 2) a novel split anode plate has led to a reduction in misidentified 36S. A peak-stabilizing routine incorporated in the data acquisition system has allowed us to run at higher counting rates. Changing to propane gas has reduced random signal amplitude shifts.

  6. High pressure xenon ionization detector

    DOEpatents

    Markey, J.K.

    1989-11-14

    A method is provided for detecting ionization comprising allowing particles that cause ionization to contact high pressure xenon maintained at or near its critical point and measuring the amount of ionization. An apparatus is provided for detecting ionization, the apparatus comprising a vessel containing a ionizable medium, the vessel having an inlet to allow high pressure ionizable medium to enter the vessel, a means to permit particles that cause ionization of the medium to enter the vessel, an anode, a cathode, a grid and a plurality of annular field shaping rings, the field shaping rings being electrically isolated from one another, the anode, cathode, grid and field shaping rings being electrically isolated from one another in order to form an electric field between the cathode and the anode, the electric field originating at the anode and terminating at the cathode, the grid being disposed between the cathode and the anode, the field shaping rings being disposed between the cathode and the grid, the improvement comprising the medium being xenon and the vessel being maintained at a pressure of 50 to 70 atmospheres and a temperature of 0 to 30 C. 2 figs.

  7. High pressure xenon ionization detector

    DOEpatents

    Markey, John K.

    1989-01-01

    A method is provided for detecting ionization comprising allowing particles that cause ionization to contact high pressure xenon maintained at or near its critical point and measuring the amount of ionization. An apparatus is provided for detecting ionization, the apparatus comprising a vessel containing a ionizable medium, the vessel having an inlet to allow high pressure ionizable medium to enter the vessel, a means to permit particles that cause ionization of the medium to enter the vessel, an anode, a cathode, a grid and a plurality of annular field shaping rings, the field shaping rings being electrically isolated from one another, the anode, cathode, grid and field shaping rings being electrically isolated from one another in order to form an electric field between the cathode and the anode, the electric field originating at the anode and terminating at the cathode, the grid being disposed between the cathode and the anode, the field shaping rings being disposed between the cathode and the grid, the improvement comprising the medium being xenon and the vessel being maintained at a pressure of 50 to 70 atmospheres and a temperature of 0.degree. to 30.degree. C.

  8. MBMS sampling from highly heated gas mixtures (1000-3000 K) and weakly ionized RF plasmas (800-2800 K) or laser plasmas (5000-20,000 K)

    SciTech Connect

    Campargue, R.; Lebehot, A.

    1995-03-01

    The properties of the free jet expansion and molecular beam skimming can be applied to the sampling of a wide variety of gaseous media, as those considered in this workshop: reactive systems, high temperature gases, flames, plasma flows, shock zone gases, laser ablation plumes, gas phase in CVD or in high temperature corrosion, etc. In the authors` laboratory, as well as in many molecular beam groups, the MBMS sampling is not generally made for analysing the gas stagnating in the nozzle, but for optimizing and using the beam source in research experiments. Nevertheless, this beam optimization has been of great interest to investigate and minimize the distortions through the interface used for MS sampling. They are due to the reality of the gas, the deviations from ideal free jet expansion, and the possible interactions along the MBMS sampling system, from the nozzle sampler to the quadrupole analyser. The first part of this paper is an historical review on the various distortions observed at Saclay in skimming, or in MBMS sampling from room temperature gases or gas mixtures. The second part deals with neutral energetic particles resulting either from the cluster generation in expansion or from the seeding and/or heating techniques. Finally the last part of the paper is devoted to recent developments in MBMS sampling of weakly ionized RF plasmas (800-2800 K) and laser sustained plasmas (5000-20000 K). The presentation is made with large reference to the authors` previous papers, especially their later review on jets and beams.

  9. Viscosity Coefficient Curve Fits for Ionized Gas Species Grant Palmer

    NASA Technical Reports Server (NTRS)

    Palmer, Grant; Arnold, James O. (Technical Monitor)

    2001-01-01

    Viscosity coefficient curve fits for neutral gas species are available from many sources. Many do a good job of reproducing experimental and computational chemistry data. The curve fits are usually expressed as a function of temperature only. This is consistent with the governing equations used to derive an expression for the neutral species viscosity coefficient. Ionized species pose a more complicated problem. They are subject to electrostatic as well as intermolecular forces. The electrostatic forces are affected by a shielding phenomenon where electrons shield the electrostatic forces of positively charged ions beyond a certain distance. The viscosity coefficient for an ionized gas species is a function of both temperature and local electron number density. Currently available curve fits for ionized gas species, such as those presented by Gupta/Yos, are a function of temperature only. What they did was to assume an electron number density. The problem is that the electron number density they assumed was unrealistically high. The purpose of this paper is two-fold. First, the proper expression for determining the viscosity coefficient of an ionized species as a function of both temperature and electron number density will be presented. Then curve fit coefficients will be developed using the more realistic assumption of an equilibrium electron number density. The results will be compared against previous curve fits and against highly accurate computational chemistry data.

  10. Viscosity Coefficient Curve Fits for Ionized Gas Species Grant Palmer

    NASA Technical Reports Server (NTRS)

    Palmer, Grant; Arnold, James O. (Technical Monitor)

    2001-01-01

    Viscosity coefficient curve fits for neutral gas species are available from many sources. Many do a good job of reproducing experimental and computational chemistry data. The curve fits are usually expressed as a function of temperature only. This is consistent with the governing equations used to derive an expression for the neutral species viscosity coefficient. Ionized species pose a more complicated problem. They are subject to electrostatic as well as intermolecular forces. The electrostatic forces are affected by a shielding phenomenon where electrons shield the electrostatic forces of positively charged ions beyond a certain distance. The viscosity coefficient for an ionized gas species is a function of both temperature and local electron number density. Currently available curve fits for ionized gas species, such as those presented by Gupta/Yos, are a function of temperature only. What they did was to assume an electron number density. The problem is that the electron number density they assumed was unrealistically high. The purpose of this paper is two-fold. First, the proper expression for determining the viscosity coefficient of an ionized species as a function of both temperature and electron number density will be presented. Then curve fit coefficients will be developed using the more realistic assumption of an equilibrium electron number density. The results will be compared against previous curve fits and against highly accurate computational chemistry data.

  11. Laboratory and Ambient Measurements of Oxidized Organic Compounds in the Gas Phase Using Nitrate Ion Chemical Ionization Coupled with High Resolution Time-of-Flight Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Massoli, P.; Stark, H.; Canagaratna, M. R.; Krechmer, J.; Lambe, A. T.; Isaacman-VanWertz, G. A.; Nowak, J. B.; Kimmel, J.; Kroll, J. H.; Jayne, J. T.; Worsnop, D. R.

    2015-12-01

    Chemical Ionization Mass Spectrometry (CIMS) is a widely used technique for molecular level characterization of inorganic and organic gas phase species. Here we present laboratory and ambient measurements of gaseous organic compounds by means of a High Resolution Time-of-Flight Chemical Ionization Mass Spectrometry (HR-ToF-CIMS) using nitrate ion (NO3-) chemistry, which recently has proven capable of selectively detecting oxidized organic molecules in the gas-phase via clustering with NO3- and its high order clusters. Such low and extremely low volatility organic compounds (LVOC, ELVOC) have an important role in particulate phase chemistry and formation of secondary organic aerosol (SOA). The HR-ToF-CIMS was deployed during the Southern Oxidant and Aerosol Study (SOAS) at the forest site in Centreville, AL (June 1 - July 15, 2013), where emissions were dominated by biogenic volatile organic compounds (BVOC), occasionally mixing with anthropogenic emissions. During SOAS, the HR-ToF-CIMS detected oxidation products of both isoprene (typically C5 LVOC) and terpenes (typically C10 ELVOC). The isoprene-related LVOC showed a diurnal cycle with a day time peak, while two groups of terpene ELVOC were identified, one peaking at night and one peaking during the day. Positive Matrix Factorization (PMF) analyses are applied to the dataset to further interpret these observations. The effect of anthropogenic pollution on the biogenic-dominated environment was also investigated during periods of elevated nitrous and sulfur dioxide levels. To further aid in interpretation of the SOAS dataset, oxidized organic molecules were produced via OH and O3 initiated oxidation of biogenic gas-phase precursors in targeted laboratory studies and detected using the HR-ToF-CIMS. Spectra were obtained in these studies over a range of simulated atmospheric conditions.

  12. The distribution of warm ionized gas in NGC 891

    SciTech Connect

    Rand, R.J.; Kulkarni, S.R.; Hester, J.J. Infrared Processing and Analysis Center, Pasadena, CA )

    1990-03-01

    Narrow-band imaging is presented of the edge-on spiral NGC 891 in the H-alpha and S II 6716, 6731 A forbidden lines. Emission from H II regions confined to the plane of the galaxy and from diffuse gas up to about 4 kpc off the plane is readily detected. The full radial extent of the diffuse emission in the plane is about 30 kpc. NGC 891 is found to have a surface density of diffuse ionized gas twice the Galactic value, a thicker ionized gas layer, and a larger surface density of ionized gas relative to neutral gas. These are interpreted as consequences of a relatively high level of star formation in this galaxy. Other star formation tracers indicate the same conclusion. Many vertical H-alpha filaments, or 'worms,' extending to over 2 kpc off the plane of the galaxy are seen. These worms are interpreted in terms of chimney models for the interstellar media of spirals. 19 refs.

  13. Atmospheric pressure soft ionization for gas chromatography with dielectric barrier discharge ionization-mass spectrometry (GC-DBDI-MS).

    PubMed

    Mirabelli, Mario F; Wolf, Jan-Christoph; Zenobi, Renato

    2017-05-30

    In this study, a gas chromatography (GC) system was interfaced to a high-resolution Orbitrap mass spectrometer by means of an active capillary plasma ionization source, based on dielectric barrier discharge ionization (DBDI). This allowed highly efficient soft ionization of gas-phase, chromatographically resolved compounds at ambient pressure. Several pesticides and illicit drugs were analyzed, and the limits of detections (LODs) were as low as 30 pg mL(-1) for the GC-DBDI-MS coupling (corresponding to 60 fg on-column sensitivity) and 30 fg mL(-1) for SPME-GC-DBDI-MS.

  14. Picosecond ionization dynamics in femtosecond filaments at high pressures

    NASA Astrophysics Data System (ADS)

    Gao, Xiaohui; Patwardhan, Gauri; Schrauth, Samuel; Zhu, Daiwei; Popmintchev, Tenio; Kapteyn, Henry C.; Murnane, Margaret M.; Romanov, Dmitri A.; Levis, Robert J.; Gaeta, Alexander L.

    2017-01-01

    We investigate the plasma dynamics inside a femtosecond-pulse-induced filament generated in an argon gas for a wide range of pressures up to 60 bar. At higher pressures, we observe ionization immediately following a pulse, with up to a threefold increase in the electron density within 30 ps after the filamentary propagation of a femtosecond pulse. Our study suggests that this picosecond evolution can be attributed to collisional ionization including Penning and associative ionizations and electron-impact ionization of excited atoms generated during the pulse. The dominance of excited atoms over ionized atoms at the end of the pulse also indicates an intrapulse inhibition of avalanche ionization. This delayed ionization dynamics provides evidence for diagnosing atomic and molecular excitation and ionization in intense laser interaction with high-pressure gases.

  15. HIGH-TEMPERATURE IONIZATION IN PROTOPLANETARY DISKS

    SciTech Connect

    Desch, Steven J.; Turner, Neal J.

    2015-10-01

    We calculate the abundances of electrons and ions in the hot (≳500 K), dusty parts of protoplanetary disks, treating for the first time the effects of thermionic and ion emission from the dust grains. High-temperature ionization modeling has involved simply assuming that alkali elements such as potassium occur as gas-phase atoms and are collisionally ionized following the Saha equation. We show that the Saha equation often does not hold, because free charges are produced by thermionic and ion emission and destroyed when they stick to grain surfaces. This means the ionization state depends not on the first ionization potential of the alkali atoms, but rather on the grains’ work functions. The charged species’ abundances typically rise abruptly above about 800 K, with little qualitative dependence on the work function, gas density, or dust-to-gas mass ratio. Applying our results, we find that protoplanetary disks’ dead zone, where high diffusivities stifle magnetorotational turbulence, has its inner edge located where the temperature exceeds a threshold value ≈1000 K. The threshold is set by ambipolar diffusion except at the highest densities, where it is set by Ohmic resistivity. We find that the disk gas can be diffusively loaded onto the stellar magnetosphere at temperatures below a similar threshold. We investigate whether the “short-circuit” instability of current sheets can operate in disks and find that it cannot, or works only in a narrow range of conditions; it appears not to be the chondrule formation mechanism. We also suggest that thermionic emission is important for determining the rate of Ohmic heating in hot Jupiters.

  16. Determination of red blood cell fatty acid profiles: Rapid and high-confident analysis by chemical ionization-gas chromatography-tandem mass spectrometry.

    PubMed

    Schober, Yvonne; Wahl, Hans Günther; Renz, Harald; Nockher, Wolfgang Andreas

    2017-01-01

    Cellular fatty acid (FA) profiles have been acknowledged as biomarkers in various human diseases. Nevertheless, common FA analysis by gas chromatography mass spectrometry (GC-MS) requires long analysis time. Hence, there is a need for feasible methods for high throughput analysis in clinical studies. FA was extracted from red blood cells (RBC) and derivatized to fatty acid methyl esters (FAME). A method using gas chromatography tandem mass spectrometry (GC-MS/MS) with ammonia-induced chemical ionization (CI) was developed for the analysis of FA profiles in human RBC. We compared this method with classical single GC-MS using electron impact ionization (EI). The FA profiles of 703 RBC samples were determined by GC-MS/MS. In contrast to EI ammonia-induced CI resulted in adequate amounts of molecular ions for further fragmentation of FAME. Specific fragments for confident quantification and fragmentation were determined for 45 FA. The GC-MS/MS method has a total run time of 9min compared to typical analysis times of up to 60min in conventional GC-MS. Intra and inter assay variations were <10% for all FA analyzed. Analysis of RBC FA composition revealed an age-dependent increase of the omega-3 eicosapentaenoic and docosahexaenoic acid, and a decline of the omega-6 linoleic acid with a corresponding rise of the omega-3 index. The combination of ammonia-induced CI and tandem mass spectrometry after GC separation allows for high-throughput, robust and confident analysis of FA profiles in the clinical laboratory. Copyright © 2016. Published by Elsevier B.V.

  17. Ionized gas at the edge of the central molecular zone

    NASA Astrophysics Data System (ADS)

    Langer, W. D.; Goldsmith, P. F.; Pineda, J. L.; Velusamy, T.; Requena-Torres, M. A.; Wiesemeyer, H.

    2015-04-01

    Context. The edge of the central molecular zone (CMZ) is the location where massive dense molecular clouds with large internal velocity dispersions transition to the surrounding more quiescent and lower CO emissivity region of the Galaxy. Little is known about the ionized gas surrounding the molecular clouds and in the transition region. Aims: We determine the properties of the ionized gas at the edge of the CMZ near Sgr E using observations of N+ and C+. Methods: We observed a small portion of the edge of the CMZ near Sgr E with spectrally resolved [C ii] 158 μm and [N ii] 205 μm fine structure lines at six positions with the GREAT instrument on SOFIA and in [C ii] using Herschel HIFI on-the-fly strip maps. We use the [N ii] spectra along with a radiative transfer model to calculate the electron density of the gas and the [C ii] maps to illuminate the morphology of the ionized gas and model the column density of CO-dark H2. Results: We detect two [C ii] and [N ii] velocity components, one along the line of sight to a CO molecular cloud at - 207 km s-1 associated with Sgr E and the other at -174 km s-1 outside the edge of another CO cloud. From the [N ii] emission we find that the average electron density is in the range of ~5 to 21 cm-3 for these features. This electron density is much higher than that of the disk's warm ionized medium, but is consistent with densities determined for bright diffuse H ii nebula. The column density of the CO-dark H2 layer in the -207 km s-1 cloud is ~1-2 × 1021 cm-2 in agreement with theoretical models. The CMZ extends further out in Galactic radius by ~7 to 14 pc in ionized gas than it does in molecular gas traced by CO. Conclusions: The edge of the CMZ likely contains dense hot ionized gas surrounding the neutral molecular material. The high fractional abundance of N+ and high electron density require an intense EUV field with a photon flux of order 106 to 107 photons cm-2 s-1, and/or efficient proton charge exchange with

  18. Development of a High-Resolution H3O+ Chemical Ionization Mass Spectrometer for Gas-phase Hydrocarbons and its Application During the 2015 SONGNEX Aircraft Campaign

    NASA Astrophysics Data System (ADS)

    Koss, A.; Yuan, B.; De Gouw, J. A.; Warneke, C.; Stark, H.

    2015-12-01

    In-situ time-of-flight chemical ionization mass spectrometers (ToF-CIMS) using H3O+ reagent ion chemistry (PTR-MS) are a relatively new technique in detection of gas-phase hydrocarbons, and recent improvements in instrument sensitivity, mass resolution, and ease of field deployment have expanded their use in atmospheric chemistry. The comparatively low-energy H3O+ ionization technique is ideal for measuring complex mixtures of hydrocarbons, and, compared to conventional quadrupole PTRMS, the newest generation of ToF-CIMS measure many more species simultaneously and with a sensitivity that is as high as a quadrupole PTR-MS. We describe here the development of a commercially available ToF CIMS into an H3O+CIMS suitable for deployment on aircraft, and its application during an aircraft campaign studying emissions from oil and natural gas extraction industry. We provide an overview of instrument development and specifications, including design, characterization, and field operation. We then discuss data processing and interpretation. First, we investigate determination of intensities of poorly resolved peaks. The mass resolution of the present instrument (m/Δm ~4500) enables separate analysis of many isobaric peaks, but peaks are also frequently not fully resolved. Using results from laboratory tests, we quantify how the accuracy can be limited by the overlap in neighboring peaks, and compare to theoretical predictions from literature. We then briefly describe our method for quality assurance of reported compounds, and correction for background and humidity effects. Finally, we present preliminary results from the first field deployment of this instrument during the Spring 2015 SONGNEX aircraft campaign. This campaign sampled emissions from oil and natural gas extraction regions and associated infrastructure in the Western and Central United States. We will highlight results that illustrate (1) new scientific capability from improved mass resolution, which

  19. Turbulence in the ionized gas of the Orion nebula

    NASA Astrophysics Data System (ADS)

    Arthur, S. J.; Medina, S.-N. X.; Henney, W. J.

    2016-12-01

    In order to study the nature, origin, and impact of turbulent velocity fluctuations in the ionized gas of the Orion nebula, we apply a variety of statistical techniques to observed velocity cubes. The cubes are derived from high resolving power (R ≈ 40 000) longslit spectroscopy of optical emission lines that span a range of ionizations. From velocity channel analysis (VCA), we find that the slope of the velocity power spectrum is consistent with predictions of Kolmogorov theory between scales of 8 and 22 arcsec (0.02 to 0.05 pc). The outer scale, which is the dominant scale of density fluctuations in the nebula, approximately coincides with the autocorrelation length of the velocity fluctuations that we determine from the second-order velocity structure function. We propose that this is the principal driving scale of the turbulence, which originates in the autocorrelation length of dense cores in the Orion molecular filament. By combining analysis of the non-thermal linewidths with the systematic trends of velocity centroid versus ionization, we find that the global champagne flow and smaller scale turbulence each contribute in equal measure to the total velocity dispersion, with respective root-mean-square widths of 4-5 km s-1. The turbulence is subsonic and can account for only one half of the derived variance in ionized density, with the remaining variance provided by density gradients in photoevaporation flows from globules and filaments. Intercomparison with results from simulations implies that the ionized gas is confined to a thick shell and does not fill the interior of the nebula.

  20. Simultaneous resonant enhanced multiphoton ionization and electron avalanche ionization in gas mixtures

    SciTech Connect

    Shneider, Mikhail N.; Zhang Zhili; Miles, Richard B.

    2008-07-15

    Resonant enhanced multiphoton ionization (REMPI) and electron avalanche ionization (EAI) are measured simultaneously in Ar:Xe mixtures at different partial pressures of mixture components. A simple theory for combined REMPI+EAI in gas mixture is developed. It is shown that the REMPI electrons seed the avalanche process, and thus the avalanche process amplifies the REMPI signal. Possible applications are discussed.

  1. An advanced oxidation process using ionized gas for wastewater treatment.

    PubMed

    Lee, Eun Ju; Chung, Paul Gene; Kwak, Dong Heui; Kim, Lee Hyung; Kim, Min Jeong

    2010-01-01

    This study on removing non-degradable materials in wastewater focused primarily on advanced oxidation methods such as ozone, ozone/UV and ozone/H2O2. Wastewater treatment using an ionized gas from plasma has been actively progressing. The ionized gas involves reactive species such as O2+, O2- cluster, O radical and OH radical. Since the ionized gas method has such outstanding characteristics as relatively simple structures, non-calorification, non-toxicity and low electricity consumption, it evidently of interest as a new process. A series of experiments were conducted to demonstrate the feasibility of ionized gas as a useful element for the diminution of nondegradable organic matters. On the other hand, a large amount of organic matters were changed to hydrophilic and the compounds containing aromatic functional group gradually decreased. The results implied that the ionized gas has been able to degrade the non-biodegradable organic matters. Therefore, the oxidation process by using an ionized gas process could be considered as an effective alternative unit in water and wastewater treatment plants.

  2. Ionized gas in the Irr galaxy IC 10: The emission spectrum and ionization sources

    NASA Astrophysics Data System (ADS)

    Arkhipova, V. P.; Egorov, O. V.; Lozinskaya, T. A.; Moiseev, A. V.

    2011-02-01

    We present the observations of the Irr galaxy IC 10 at the 6-m SAO telescope with the panoramic Multi-Pupil Fiber Spectrograph (MPFS). Based on the results of these observations and our long-slit spectroscopy performed previously, we have investigated the ionized-gas emission spectrum in the region of intense star formation and refined the gas metallicity estimates. We show that the “diagnostic diagrams” constructed from our observations agree best with the new improved ionization models by Martin-Manjon et al. Using these models, we have determined the electron density and gas ionization parameter and ionizing-cluster characteristics, the age and mass, from the spectra of the investigated HII regions. The cluster ages and masses are shown to be within the ranges 2.5-5 Myr and (0.2-1) × 105 M ⊗, respectively.

  3. Laser induced avalanche ionization in gases or gas mixtures with resonantly enhanced multiphoton ionization or femtosecond laser pulse pre-ionization

    SciTech Connect

    Shneider, Mikhail N.; Miles, Richard B.

    2012-08-15

    The paper discusses the requirements for avalanche ionization in gas or gas mixtures initiated by REMPI or femtosecond-laser pre-ionization. Numerical examples of dependencies on partial composition for Ar:Xe gas mixture with REMPI of argon and subsequent classic avalanche ionization of Xe are presented.

  4. The rise of ionized gas in the Magellanic Stream

    NASA Astrophysics Data System (ADS)

    Hernandez, Michael; Barger, Kathleen; Smart, Brianna; Haffner, L. Matthew

    2017-01-01

    The Small and Large Magellanic Clouds are a pair of interacting galaxies near the Milky Way. Tidal interactions have stripped gas from these galaxies, leaving behind gaseous debris such as the Magellanic Stream. We explore the morphology and kinematics of the neutral and ionized hydrogen gas in the trailing stream traveling toward the Milky Way. This comparison provides us with insight into the physical processes that are affecting the gas flowing through the Galactic halo. This is done using mapped H-alpha emission-line spectroscopy, obtained with the Wisconsin H-alpha Mapper (WHAM), and archival 21-cm HI observations of the Stream near the Magellanic Clouds. We found that the neutral and ionized gas spatially and kinematically trace each other. With a map of the ionized gas in hand, we will continue to study the survival of this tidal relic.

  5. Hydration of Gas-Phase Ions Formed by Electrospray Ionization

    PubMed Central

    Rodriguez-Cruz, Sandra E.; Klassen, John S.; Williams, Evan R.

    2005-01-01

    The hydration of gas-phase ions produced by electrospray ionization was investigated. Evidence that the hydrated ions are formed by two mechanisms is presented. First, solvent condensation during the expansion inside the electrospray source clearly occurs. Second, some solvent evaporation from more extensively solvated ions or droplets is apparent. To the extent that these highly solvated ions have solution-phase structures, then the final isolated gas-phase structure of the ion will be determined by the solvent evaporation process. This process was investigated for hydrated gramicidin S in a Fourier-transform mass spectrometer. Unimolecular dissociation rate constants of isolated gramicidin S ions with between 2 and 14 associated water molecules were measured. These rate constants increased from 16 to 230 s−1 with increasing hydration, with smaller values corresponding to magic numbers. PMID:10497808

  6. Gas chromatography fractionation platform featuring parallel flame-ionization detection and continuous high-resolution analyte collection in 384-well plates.

    PubMed

    Jonker, Willem; Clarijs, Bas; de Witte, Susannah L; van Velzen, Martin; de Koning, Sjaak; Schaap, Jaap; Somsen, Govert W; Kool, Jeroen

    2016-09-02

    Gas chromatography (GC) is a superior separation technique for many compounds. However, fractionation of a GC eluate for analyte isolation and/or post-column off-line analysis is not straightforward, and existing platforms are limited in the number of fractions that can be collected. Moreover, aerosol formation may cause serious analyte losses. Previously, our group has developed a platform that resolved these limitations of GC fractionation by post-column infusion of a trap solvent prior to continuous small-volume fraction collection in a 96-wells plate (Pieke et al., 2013 [17]). Still, this GC fractionation set-up lacked a chemical detector for the on-line recording of chromatograms, and the introduction of trap solvent resulted in extensive peak broadening for late-eluting compounds. This paper reports advancements to the fractionation platform allowing flame ionization detection (FID) parallel to high-resolution collection of a full GC chromatograms in up to 384 nanofractions of 7s each. To this end, a post-column split was incorporated which directs part of the eluate towards FID. Furthermore, a solvent heating device was developed for stable delivery of preheated/vaporized trap solvent, which significantly reduced band broadening by post-column infusion. In order to achieve optimal analyte trapping, several solvents were tested at different flow rates. The repeatability of the optimized GC fraction collection process was assessed demonstrating the possibility of up-concentration of isolated analytes by repetitive analyses of the same sample. The feasibility of the improved GC fractionation platform for bioactivity screening of toxic compounds was studied by the analysis of a mixture of test pesticides, which after fractionation were subjected to a post-column acetylcholinesterase (AChE) assay. Fractions showing AChE inhibition could be unambiguously correlated with peaks from the parallel-recorded FID chromatogram. Copyright © 2016 Elsevier B.V. All rights

  7. Helium Ionization in the Diffuse Ionized Gas Surrounding UCH ii Regions

    NASA Astrophysics Data System (ADS)

    Anish Roshi, D.; Churchwell, E.; Anderson, L. D.

    2017-04-01

    We present measurements of the singly ionized helium-to-hydrogen ratio ({n}{{He}+}/{n}{{{H}}+}) toward diffuse gas surrounding three ultracompact H ii (UCH ii) regions: G10.15-0.34, G23.46-0.20, and G29.96-0.02. We observe radio recombination lines of hydrogen and helium near 5 GHz using the GBT to measure the {n}{{He}+}/{n}{{{H}}+} ratio. The measurements are motivated by the low helium ionization observed in the warm ionized medium and in the inner Galaxy diffuse ionized regions. Our data indicate that the helium is not uniformly ionized in the three observed sources. Helium lines are not detected toward a few observed positions in sources G10.15-0.34 and G23.46-0.20, and the upper limits of the {n}{{He}+}/{n}{{{H}}+} ratio obtained are 0.03 and 0.05, respectively. The selected sources harbor stars of type O6 or hotter as indicated by helium line detection toward the bright radio continuum emission from the sources with mean {n}{{He}+}/{n}{{{H}}+} value 0.06 ± 0.02. Our data thus show that helium in diffuse gas located a few parsecs away from the young massive stars embedded in the observed regions is not fully ionized. We investigate the origin of the nonuniform helium ionization and rule out the possibilities (a) that the helium is doubly ionized in the observed regions and (b) that the low {n}{{He}+}/{n}{{{H}}+} values are due to additional hydrogen ionizing radiation produced by accreting low-mass stars. We find that selective absorption of ionizing photons by dust can result in low helium ionization but needs further investigation to develop a self-consistent model for dust in H ii regions.

  8. Helium Ionization in the Diffuse Ionized Gas Surrounding UCH ii Regions

    NASA Astrophysics Data System (ADS)

    Roshi, D. Anish; Churchwell, E.; Anderson, L. D.

    2017-04-01

    We present measurements of the singly ionized helium-to-hydrogen ratio ({n}{{He}+}/{n}{{{H}}+}) toward diffuse gas surrounding three ultracompact H ii (UCH ii) regions: G10.15-0.34, G23.46-0.20, and G29.96-0.02. We observe radio recombination lines of hydrogen and helium near 5 GHz using the GBT to measure the {n}{{He}+}/{n}{{{H}}+} ratio. The measurements are motivated by the low helium ionization observed in the warm ionized medium and in the inner Galaxy diffuse ionized regions. Our data indicate that the helium is not uniformly ionized in the three observed sources. Helium lines are not detected toward a few observed positions in sources G10.15-0.34 and G23.46-0.20, and the upper limits of the {n}{{He}+}/{n}{{{H}}+} ratio obtained are 0.03 and 0.05, respectively. The selected sources harbor stars of type O6 or hotter as indicated by helium line detection toward the bright radio continuum emission from the sources with mean {n}{{He}+}/{n}{{{H}}+} value 0.06 ± 0.02. Our data thus show that helium in diffuse gas located a few parsecs away from the young massive stars embedded in the observed regions is not fully ionized. We investigate the origin of the nonuniform helium ionization and rule out the possibilities (a) that the helium is doubly ionized in the observed regions and (b) that the low {n}{{He}+}/{n}{{{H}}+} values are due to additional hydrogen ionizing radiation produced by accreting low-mass stars. We find that selective absorption of ionizing photons by dust can result in low helium ionization but needs further investigation to develop a self-consistent model for dust in H ii regions.

  9. Air ionization as a control technology for off-gas emissions of volatile organic compounds.

    PubMed

    Kim, Ki-Hyun; Szulejko, Jan E; Kumar, Pawan; Kwon, Eilhann E; Adelodun, Adedeji A; Reddy, Police Anil Kumar

    2017-06-01

    High energy electron-impact ionizers have found applications mainly in industry to reduce off-gas emissions from waste gas streams at low cost and high efficiency because of their ability to oxidize many airborne organic pollutants (e.g., volatile organic compounds (VOCs)) to CO2 and H2O. Applications of air ionizers in indoor air quality management are limited due to poor removal efficiency and production of noxious side products, e.g., ozone (O3). In this paper, we provide a critical evaluation of the pollutant removal performance of air ionizing system through comprehensive review of the literature. In particular, we focus on removal of VOCs and odorants. We also discuss the generation of unwanted air ionization byproducts such as O3, NOx, and VOC oxidation intermediates that limit the use of air-ionizers in indoor air quality management. Copyright © 2017. Published by Elsevier Ltd.

  10. Influence of ionization on ultrafast gas-based nonlinear fiber optics.

    PubMed

    Chang, W; Nazarkin, A; Travers, J C; Nold, J; Hölzer, P; Joly, N Y; Russell, P St J

    2011-10-10

    We numerically investigate the effect of ionization on ultrashort high-energy pulses propagating in gas-filled kagomé-lattice hollow-core photonic crystal fibers by solving an established uni-directional field equation. We consider the dynamics of two distinct regimes: ionization induced blue-shift and resonant dispersive wave emission in the deep-UV. We illustrate how the system evolves between these regimes and the changing influence of ionization. Finally, we consider the effect of higher ionization stages.

  11. The ionization conditions in the Milky Way halo - Infalling gas toward the North Galactic Pole

    NASA Technical Reports Server (NTRS)

    Danly, Laura

    1992-01-01

    Observations of gas in the Milky Way halo are studied with an eye toward the theoretical predictions of the Galactic Fountain model for the production of halo gas. Data are shown that indicate significant variations in the ionization conditions in infalling halo gas in the northern galactic hemisphere. Understanding the nature of Milky Way halo gas plays a critical role in interpreting QSO absorption lines in the investigation of galaxies at high redshift.

  12. The ionization conditions in the Milky Way halo - Infalling gas toward the North Galactic Pole

    NASA Technical Reports Server (NTRS)

    Danly, Laura

    1992-01-01

    Observations of gas in the Milky Way halo are studied with an eye toward the theoretical predictions of the Galactic Fountain model for the production of halo gas. Data are shown that indicate significant variations in the ionization conditions in infalling halo gas in the northern galactic hemisphere. Understanding the nature of Milky Way halo gas plays a critical role in interpreting QSO absorption lines in the investigation of galaxies at high redshift.

  13. Ionization fronts in coupled MHD-gas simulations

    NASA Astrophysics Data System (ADS)

    Wilson, A. D.; Diver, D. A.

    2017-09-01

    Partially ionized plasmas are ubiquitous in both nature and the laboratory, and their behaviour is best described by models which take into account the interactions between the neutral and charged species. We present a new non-linear, 3-dimensional, finite difference Gas-MHD Interactions Code designed to solve simultaneously the time evolution of fluid equations of both species in the conservation form as well as collisional interactions between them via appropriate choices of source term; in particular, we present results from this code in simulating Alfvén ionization in a partially ionized plasma. In this fashion, larger changes in the ionization fraction than were addressable in the linear limit are possible. Alfvén ionization is shown to impart plasmas with an inherent resistance to rapid recombination, where the recombination itself is significant enough to drive relative motion between the ionised and neutral species at speeds in excess of the critical velocity.

  14. Fluid hydrogen at high density - Pressure ionization

    NASA Technical Reports Server (NTRS)

    Saumon, Didier; Chabrier, Gilles

    1992-01-01

    The Helmholtz-free-energy model for nonideal mixtures of hydrogen atoms and molecules by Saumon and Chabrier (1991) is extended to describe dissociation and ionization in similar mixtures in chemical equilibrium. A free-energy model is given that describes partial ionization in the pressure and temperature ionization region. The plasma-phase transition predicted by the model is described for hydrogen mixtures including such components as H2, H, H(+), and e(-). The plasma-phase transition has a critical point at Tc = 15,300 K and Pc = 0.614 Mbar, and thermodynamic instability is noted in the pressure-ionization regime. The pressure dissociation and ionization of fluid hydrogen are described well with the model yielding information on the nature of the plasma-phase transition. The model is shown to be valuable for studying dissociation and ionization in astrophysical objects and in high-pressure studies where pressure and temperature effects are significant.

  15. Axisymmetric model of the ionized gas in the Orion Nebula

    NASA Technical Reports Server (NTRS)

    Rubin, R. H.; Simpson, J. P.; Haas, M. R.; Erickson, E. F.

    1991-01-01

    New ionization and thermal equilibrium models for the ionized gas in the Orion Nebula with an axisymmetric two-dimensional 'blister' geometry/density distribution are presented. The HII region is represented more realistically than in previous models, while the physical detail of the microphysics and radiative transfer of the earlier spherical modeling is maintained. The predicted surface brightnesses are compared with observations for a large set of lines at different positions to determine the best-fitting physical parameters. The model explains the strong singly ionized line emission along the lines of sight near the Trapezium.

  16. Axisymmetric model of the ionized gas in the Orion Nebula

    NASA Technical Reports Server (NTRS)

    Rubin, R. H.; Simpson, J. P.; Haas, M. R.; Erickson, E. F.

    1991-01-01

    New ionization and thermal equilibrium models for the ionized gas in the Orion Nebula with an axisymmetric two-dimensional 'blister' geometry/density distribution are presented. The HII region is represented more realistically than in previous models, while the physical detail of the microphysics and radiative transfer of the earlier spherical modeling is maintained. The predicted surface brightnesses are compared with observations for a large set of lines at different positions to determine the best-fitting physical parameters. The model explains the strong singly ionized line emission along the lines of sight near the Trapezium.

  17. New design of high performance ionizing bar

    NASA Astrophysics Data System (ADS)

    Wang, Ronggang; Sun, Yurong

    2013-03-01

    This paper introduces a new design of DC-pulse ionizing bar to solve the problem of imbalance offset voltage for the AC ionizing bar, which is easily affected by the environment, as well as indicate the final tests. The new design mainly includes five parts: power supply circuit, main control unit, logic circuit, high frequency transformer unit, and feedback unit. The ionizing bar can automatically adjust the discharge voltage, pulse frequency and pulse width to balance the positive and negative ions. The final test results indicate that the DC ionizing bar owns good effect in electrostatic elimination.

  18. Shock-wave structure in a partially ionized gas

    NASA Technical Reports Server (NTRS)

    Lu, C. S.; Huang, A. B.

    1974-01-01

    The structure of a steady plane shock in a partially ionized gas has been investigated using the Boltzmann equation with a kinetic model as the governing equation and the discrete ordinate method as a tool. The effects of the electric field induced by the charge separation on the shock structure have also been studied. Although the three species of an ionized gas travel with approximately the same macroscopic velocity, the individual distribution functions are found to be very different. In a strong shock the atom distribution function may have double peaks, while the ion distribution function has only one peak. Electrons are heated up much earlier than ions and atoms in a partially ionized gas. Because the interactions of electrons with atoms and with ions are different, the ion temperature can be different from the atom temperature.

  19. High power gas laser amplifier

    DOEpatents

    Leland, Wallace T.; Stratton, Thomas F.

    1981-01-01

    A high power output CO.sub.2 gas laser amplifier having a number of sections, each comprising a plurality of annular pumping chambers spaced around the circumference of a vacuum chamber containing a cold cathode, gridded electron gun. The electron beam from the electron gun ionizes the gas lasing medium in the sections. An input laser beam is split into a plurality of annular beams, each passing through the sections comprising one pumping chamber.

  20. Ionized Gas in the Galactic Center: New Observations and Interpretation

    NASA Astrophysics Data System (ADS)

    Irons, Wesley T.; Lacy, John H.; Richter, Matthew J.

    2012-08-01

    We present new observations of the [Ne II] emission from the ionized gas in Sgr A West with improved resolution and sensitivity. About half of the emission comes from gas with kinematics indicating it is orbiting in a plane tipped about 25° from the Galactic plane. This plane is consistent with that derived previously for the circumnuclear molecular disk and the northern arm and western arc ionized features. However, unlike most previous studies, we conclude that the ionized gas is not moving along the ionized features, but on more nearly circular paths. The observed speeds are close to, but probably somewhat less than expected for orbital motions in the potential of the central black hole and stars and have a small inward component. The spatial distribution of the emission is well fitted by a spiral pattern. We discuss possible physical explanations for the spatial distribution and kinematics of the ionized gas, and conclude that both may be best explained by a one-armed spiral density wave, which also accounts for both the observed low velocities and the inward velocity component. We suggest that a density wave may result from the precession of elliptical orbits in the potential of the black hole and stellar mass distribution.

  1. Plasma induced by resonance enhanced multiphoton ionization in inert gas

    SciTech Connect

    Shneider, Mikhail N.; Zhang Zhili; Miles, Richard B.

    2007-12-15

    We present a detailed model for the evolution of resonance enhanced multiphoton ionization (REMPI) produced plasma during and after the ionizing laser pulse in inert gas (argon, as an example) at arbitrary pressures. Our theory includes the complete process of the REMPI plasma generation and losses, together with the changing gas thermodynamic parameters. The model shows that the plasma expansion follows a classical ambipolar diffusion and that gas heating results in a weak shock or acoustic wave. The gas becomes involved in the motion not only from the pressure gradient due to the heating, but also from the momentum transfer from the charged particles to gas atoms. The time dependence of the total number of electrons computed in theory matches closely with the results of coherent microwave scattering experiments.

  2. Novel analytical approach for brominated flame retardants based on the use of gas chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry with emphasis in highly brominated congeners.

    PubMed

    Portolés, Tania; Sales, Carlos; Gómara, Belén; Sancho, Juan Vicente; Beltrán, Joaquim; Herrero, Laura; González, María José; Hernández, Félix

    2015-10-06

    The analysis of brominated flame retardants (BFRs) commonly relies on the use of gas chromatography coupled to mass spectrometry (GC-MS) operating in electron ionization (EI) and electron capture negative ionization (ECNI) modes using quadrupole, triple quadrupole, ion trap, and magnetic sector analyzers. However, these brominated contaminants are examples of compounds for which a soft and robust ionization technique might be favorable since they show high fragmentation in EI and low specificity in ECNI. In addition, the low limits of quantification (0.01 ng/g) required by European Commission Recommendation 2014/118/EU on the monitoring of traces of BFRs in food put stress on the use of highly sensitive techniques/methods. In this work, a new approach for the extremely sensitive determination of BFRs taking profit of the potential of atmospheric pressure chemical ionization (APCI) combined with GC and triple quadrupole (QqQ) mass analyzer is proposed. The objective was to explore the potential of this approach for the BFRs determination in samples at pg/g levels, taking marine samples and a cream sample as a model. Ionization and fragmentation behavior of 14 PBDEs (congeners 28, 47, 66, 85, 99, 100, 153, 154, 183, 184, 191, 196, 197, and 209) and two novel BFRs, decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), in the GC-APCI-MS system has been investigated. The formation of highly abundant (quasi) molecular ion was the main advantage observed in relation to EI. Thus, a notable improvement in sensitivity and specificity was observed when using it as precursor ion in tandem MS. The improved detectability (LODs < 10 fg) achieved when using APCI compared to EI has been demonstrated, which is especially relevant for highly brominated congeners. Analysis of samples from an intercomparison exercise and samples from the marine field showed the potential of this approach for the reliable identification and quantification at very low

  3. Miniature triaxial metastable ionization detector for gas chromatographic trace analysis of extraterrestrial volatiles

    NASA Technical Reports Server (NTRS)

    Woeller, F. H.; Kojiro, D. R.; Carle, G. C.

    1984-01-01

    The present investigation is concerned with a miniature metastable ionization detector featuring an unconventional electrode configuration, whose performance characteristics parallel those of traditional design. The ionization detector is to be incorporated in a flight gas chromatograph (GC) for use in the Space Shuttle. The design of the detector is discussed, taking into account studies which verified the sensitivity of the detector. The triaxial design of the detector is compared with a flat-plate style. The obtained results show that the principal goal of developing a miniature, highly sensitive ionization detector for flight applications was achieved. Improved fabrication techniques will utilize glass-to-metal seals and brazing procedures.

  4. Laserspray Ionization, a New Atmospheric Pressure MALDI Method for Producing Highly Charged Gas-phase Ions of Peptides and Proteins Directly from Solid Solutions*

    PubMed Central

    Trimpin, Sarah; Inutan, Ellen D.; Herath, Thushani N.; McEwen, Charles N.

    2010-01-01

    The first example of a matrix-assisted laser desorption/ionization (MALDI) process producing multiply charged mass spectra nearly identical to those observed with electrospray ionization (ESI) is presented. MALDI is noted for its ability to produce singly charged ions, but in the experiments described here multiply charged ions are produced by laser ablation of analyte incorporated into a common MALDI matrix, 2,5-dihydroxybenzoic acid, using standard solvent-based sample preparation protocols. Laser ablation is known to produce matrix clusters in MALDI provided a threshold energy is achieved. We propose that these clusters (liquid droplets) are highly charged, and under conditions that produce sufficient matrix evaporation, ions are field-evaporated from the droplets similarly to ESI. Because of the multiple charging, advanced mass spectrometers with limited mass-to-charge range can be used for protein characterization. Thus, using an Orbitrap mass spectrometer, low femtomole quantities of proteins produce full-range mass spectra at 100,000 mass resolution with <5-ppm mass accuracy and with 1-s acquisition. Furthermore, the first example of protein fragmentation using electron transfer dissociation with MALDI is presented. PMID:19955086

  5. Laserspray ionization, a new atmospheric pressure MALDI method for producing highly charged gas-phase ions of peptides and proteins directly from solid solutions.

    PubMed

    Trimpin, Sarah; Inutan, Ellen D; Herath, Thushani N; McEwen, Charles N

    2010-02-01

    The first example of a matrix-assisted laser desorption/ionization (MALDI) process producing multiply charged mass spectra nearly identical to those observed with electrospray ionization (ESI) is presented. MALDI is noted for its ability to produce singly charged ions, but in the experiments described here multiply charged ions are produced by laser ablation of analyte incorporated into a common MALDI matrix, 2,5-dihydroxybenzoic acid, using standard solvent-based sample preparation protocols. Laser ablation is known to produce matrix clusters in MALDI provided a threshold energy is achieved. We propose that these clusters (liquid droplets) are highly charged, and under conditions that produce sufficient matrix evaporation, ions are field-evaporated from the droplets similarly to ESI. Because of the multiple charging, advanced mass spectrometers with limited mass-to-charge range can be used for protein characterization. Thus, using an Orbitrap mass spectrometer, low femtomole quantities of proteins produce full-range mass spectra at 100,000 mass resolution with <5-ppm mass accuracy and with 1-s acquisition. Furthermore, the first example of protein fragmentation using electron transfer dissociation with MALDI is presented.

  6. Screening of pesticides and polycyclic aromatic hydrocarbons in feeds and fish tissues by gas chromatography coupled to high-resolution mass spectrometry using atmospheric pressure chemical ionization.

    PubMed

    Nácher-Mestre, Jaime; Serrano, Roque; Portolés, Tania; Berntssen, Marc H G; Pérez-Sánchez, Jaume; Hernández, Félix

    2014-03-12

    This paper reports a wide-scope screening for detection and identification of pesticides and polycyclic aromatic hydrocarbons (PAHs) in feeds and fish tissues. QuEChERS sample treatment was applied, using freezing as an additional cleanup. Analysis was carried out by gas chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry with atmospheric pressure chemical ionization (GC-(APCI) QTOF MS). The qualitative validation was performed for over 133 representative pesticides and 24 PAHs at 0.01 and 0.05 mg/kg. Subsequent application of the screening method to aquaculture samples made it possible to detect several compounds from the target list, such as chlorpyrifos-methyl, pirimiphos-methyl, and ethoxyquin, among others. Light PAHs (≤4 rings) were found in both animal and vegetable samples. The reliable identification of the compounds was supported by accurate mass measurements and the presence of at least two representative m/z ions in the spectrum together with the retention time of the peak, in agreement with the reference standard. Additionally, the search was widened to include other pesticides for which standards were not available, thanks to the expected presence of the protonated molecule and/or molecular ion in the APCI spectra. This could allow the detection and tentative identification of other pesticides different from those included in the validated target list.

  7. Ionization of NO at high temperature

    NASA Technical Reports Server (NTRS)

    Hansen, C. Frederick

    1991-01-01

    Space vehicles flying through the atmosphere at high speed are known to excite a complex set of chemical reactions in the atmospheric gases, ranging from simple vibrational excitation to dissociation, atom exchange, electronic excitation, ionization, and charge exchange. Simple arguments are developed for the temperature dependence of the reactions leading to ionization of NO, including the effect of vibrational electronic thermal nonequilibrium. NO ionization is the most important source of electrons at intermediate temperatures and at higher temperatures provides the trigger electrons that ionize atoms. Based on these arguments, recommendations are made for formulae which fit observed experimental results, and which include a dependence on both a heavy particle temperature and different vibration electron temperatures. In addition, these expressions will presumably provide the most reliable extrapolation of experimental results to much higher temperatures.

  8. High pressure (>1 atm) electrospray ionization mass spectrometry.

    PubMed

    Chen, Lee Chuin; Mandal, Mridul Kanti; Hiraoka, Kenzo

    2011-03-01

    High pressure electrospray ionization mass spectrometry has been performed by pressurizing a custom made ion source chamber with compressed air to a pressure higher than the atmospheric pressure. The ion source was coupled to a commercial time-of-flight mass spectrometer using a nozzle-skimmer arrangement. The onset voltage for the electrospray of aqueous solution was found to be independent on the operating pressure. The onset voltage for the corona discharge, however, increased with the rise of pressure following the Paschen's law. Thus, besides having more working gas for the desolvation process, gaseous breakdown could also be avoided by pressurizing the ESI ion source with air to an appropriate level. Stable electrospray ionization has been achieved for the sample solution with high surface tension such as pure water in both positive and negative ion modes. Fragmentation of labile compounds during the ionization process could also be reduced by optimizing the operating pressure of the ion source.

  9. Circumnuclear ionized gas in starburst nuclei

    NASA Technical Reports Server (NTRS)

    Taniguchi, Yoshiaki

    1990-01-01

    In order to study kinematical properties of starburst nuclei (SBNs), researchers made high-resolution spectroscopy of fifteen SBNs in the H alpha region using an intensified Reticon system attached to the coude focus of the 188-cm reflector at the Okayama Astrophysical Observatory. The instrumental resolution is 21 km s(-1) Full Width Half Maximum (FWHM) at lambda sub H alpha. As for the archetypical SBN, Mrk 538 (=NGC 7714), researchers present high-resolution emission line profiles of several species of ions such as (OIII), (NII), (SII), and (OII). Main results and conclusions are summarized. It has been known that emission-line profiles of SBNs are symmetrical and narrow. However, this high-resolution spectroscopy shows that the observed emission-line profiles of the SBNs have the following asymmetrical patterns; blueward, redward, and double-peaked. It is known that such features have been observed for narrow line regions (NLRs) of active galactic nuclei (AGNs). There is no remarkable correlation between the asymmetry index and the reddening indicator such as a Balmer decrement. Thus the line asymmetry is not attributed to inhomogeneous obscuration in the emitting regions. The observed FWHMs of the H alpha emission lines cover a range from 85 km s(-1) to 318 km s(-1) and are slightly larger than those of (NII) lambda 6584A emission except for the double-peaked SBNs. The FWHMs of H alpha emission show a good correlation with sin i (i is an inclination angle of galaxy). This correlation means that the FWHMs of the SBNs suffer significantly from rotational broadening. Mrk 52 is an anomalous SBN because it has narrow emission line widths for its high inclination angle (cf. Taniguchi 1987). From the above correlation, it is estimated that the intrinsic (i.e., rotation free) FWHMs of H alpha emission are about 50 km s(-1).

  10. Circumnuclear ionized gas in starburst nuclei

    NASA Astrophysics Data System (ADS)

    Taniguchi, Yoshiaki

    1990-07-01

    In order to study kinematical properties of starburst nuclei (SBNs), researchers made high-resolution spectroscopy of fifteen SBNs in the H alpha region using an intensified Reticon system attached to the coude focus of the 188-cm reflector at the Okayama Astrophysical Observatory. The instrumental resolution is 21 km s(-1) Full Width Half Maximum (FWHM) at lambdaH alpha. As for the archetypical SBN, Mrk 538 (=NGC 7714), researchers present high-resolution emission line profiles of several species of ions such as (OIII), (NII), (SII), and (OII). Main results and conclusions are summarized. It has been known that emission-line profiles of SBNs are symmetrical and narrow. However, this high-resolution spectroscopy shows that the observed emission-line profiles of the SBNs have the following asymmetrical patterns; blueward, redward, and double-peaked. It is known that such features have been observed for narrow line regions (NLRs) of active galactic nuclei (AGNs). There is no remarkable correlation between the asymmetry index and the reddening indicator such as a Balmer decrement. Thus the line asymmetry is not attributed to inhomogeneous obscuration in the emitting regions. The observed FWHMs of the H alpha emission lines cover a range from 85 km s(-1) to 318 km s(-1) and are slightly larger than those of (NII) lambda 6584A emission except for the double-peaked SBNs. The FWHMs of H alpha emission show a good correlation with sin i (i is an inclination angle of galaxy). This correlation means that the FWHMs of the SBNs suffer significantly from rotational broadening. Mrk 52 is an anomalous SBN because it has narrow emission line widths for its high inclination angle (cf. Taniguchi 1987). From the above correlation, it is estimated that the intrinsic (i.e., rotation free) FWHMs of H alpha emission are about 50 km s(-1).

  11. Resonance ionization spectroscopy: counting noble-gas atoms

    SciTech Connect

    Hurst, G.S.; Payne, M.G.; Chen, C.H.; Willis, R.D.; Lehmann, B.E.; Kramer, S.D.

    1981-06-01

    New work on the counting of noble gas atoms, using lasers for the selective ionization and detectors for counting individual particles (electrons or positive ions) is reported. When positive ions are counted, various kinds of mass analyzers (magnetic, quadrupole, or time-of-flight) can be incorporated to provide A selectivity. It is shown that a variety of interesting and important applications can be made with atom-counting techniques which are both atomic number (Z) and mass number (A) selective.

  12. Ionizing gas breakdown waves in strong electric fields.

    NASA Technical Reports Server (NTRS)

    Klingbeil, R.; Tidman, D. A.; Fernsler, R. F.

    1972-01-01

    A previous analysis by Albright and Tidman (1972) of the structure of an ionizing potential wave driven through a dense gas by a strong electric field is extended to include atomic structure details of the background atoms and radiative effects, especially, photoionization. It is found that photoionization plays an important role in avalanche propagation. Velocities, electron densities, and temperatures are presented as a function of electric field for both negative and positive breakdown waves in nitrogen.

  13. Real-time gas and particle-phase organic acids measurement at a forest site using chemical ionization high-resolution time-of-flight mass spectrometry during BEACHON-RoMBAS

    NASA Astrophysics Data System (ADS)

    Yatavelli, L. R.; Stark, H.; Kimmel, J.; Cubison, M.; Day, D. A.; Jayne, J.; Thornton, J. A.; Worsnop, D. R.; Jimenez, J. L.

    2011-12-01

    We present measurement of organic acids in gas and aerosol particles conducted in a ponderosa pine forest during July and August 2011 as part of the Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen - Rocky Mountain Biogenic Aerosol Study (BEACHON-RoMBAS; http://tinyurl.com/BEACHON-RoMBAS). The measurement technique is based on chemical ionization, high-resolution time-of-flight mass spectrometry and utilizes a Micro-Orifice Volatilization Impactor [MOVI-CI-HR-ToFMS; Yatavelli et al., AS&T, 2010] to collect sub-micron aerosol particles while simultaneously measuring the gas-phase composition. The collected particles are subsequently analyzed by temperature-programmed thermal desorption. The reagent ion chosen for this campaign is the acetate anion (CH3C(O)O-, m/z 59), which reacts selectively via proton transfer with compounds that are stronger gas-phase acids than acetic acid [Veres et al., IJMS, 2008]. Preliminary results show substantial particle-phase concentrations of biogenic oxidation products such as hydroxy-glutaric acid, pinic acid, pinonic acid, and hydroxy-pinonic acid along with numerous lower and higher molecular weight organic acids. Correlations of the organic acid concentrations with meteorological, gas and aerosol parameters measured by other instrumentation are investigated in order to understand the formation, transformation, and partitioning of gas and particle-phase organic acids in a forested environment dominated by terpenes.

  14. High resolution UV resonance enhanced two-photon ionization spectroscopy with mass selection of biologically relevant molecules in the gas phase

    NASA Astrophysics Data System (ADS)

    Chervenkov, S.; Wang, P. Q.; Karaminkov, R.; Chakraborty, T.; Braun, Juergen E.; Neusser, Hans J.

    2005-04-01

    The high resolution Doppler-free resonance-enhanced two-photon ionization (R2PI) spectroscopy with mass selection of jet-cooled (2-12 K) molecular species is a powerful experimental method providing comprehensive information on both isolated molecules and molecular clusters. We have demonstrated for the first time that this technique can be applied to large molecules and provides detailed information on their conformational structure. It allows rotationally resolved (FWHM = 70 MHz) spectra of the vibronic bands of the S1<--S0 electronic transition of the studied molecular systems to be measured. A specially designed computer-assisted fitting routine based on genetic algorithms is used to determine their rotational constants in the ground and excited electronic states, respectively, and the transition moment ratio. To interpret the experimental information and to discriminate and unambiguously assign the observed approach to the study of the neurotransmitter molecule, ephedrine. The results elucidate the role of the intramolecular hydrogen bonds stabilizing the respective conformations and affecting their intrinsic properties.

  15. The Highly Ionized Circumgalactic Medium is Kinematically Uniform around Galaxies

    NASA Astrophysics Data System (ADS)

    Nielsen, Nikole M.; Kacprzak, Glenn G.; Muzahid, Sowgat; Churchill, Christopher W.; Murphy, Michael T.; Charlton, Jane C.

    2017-01-01

    The circumgalactic medium (CGM) traced by O vi λ λ 1031,1037 doublet absorption has been found to concentrate along the projected major and minor axes of the host galaxies. This suggests that O vi traces accreting and outflowing gas, respectively, which are key components of the baryon cycle of galaxies. We investigate this further by examining the kinematics of 29 O vi absorbers associated with galaxies at 0.13< {z}{gal}< 0.66 as a function of galaxy color, inclination, and azimuthal angle. Each galaxy was imaged with the Hubble Space Telescope (HST), and the absorption was detected in COS/HST spectra of nearby (D< 200 kpc) background quasars. We use the pixel-velocity two-point correlation function to characterize the velocity spread of the absorbers, which is a method used previously for a sample of Mg ii absorber–galaxy pairs. The absorption velocity spread for O vi is more extended than Mg ii, which suggests that the two ions trace differing components of the CGM. Again, in contrast to Mg ii, the O vi absorption velocity spreads are similar regardless of galaxy color, inclination, and azimuthal angle. This indicates that the kinematics of the high-ionization gas is not strongly influenced by the current star formation activity in the galaxy. The kinematic homogeneity of O vi absorption and its tendency to be observed mainly along the projected galaxy major and minor axes is likely due to varying ionization conditions and gas densities about the galaxy. Gas in intermediate azimuthal angles may be ionized out of the O vi phase, possibly resulting in an azimuthal angle dependence of the distribution of gas in higher ionization states.

  16. Nonlinear optical response of multiply ionized noble-gas atoms

    NASA Astrophysics Data System (ADS)

    Tarazkar(1, 3), Maryam; Romanov(2, 3), Dmitri; Levis(1, 3), Robert

    2016-05-01

    Calculation of dynamic polarizabilities and hyperpolarizabilities of ionized species using ab initio methods presents computational and conceptual difficulties, as these ionized species often have open-shell electronic system. We use multi-configurational self-consistent field (MCSCF) method with extended basis sets for calculating dynamic polarizability and second-order hyperpolarizabilities of atomic noble gases and their multiply charged cations in non-resonant regime. The calculations were performed at wavelengths ranging from about 100 nm to the red of the first multi-photon resonance all the way toward the static regime. The results were benchmarked to those of CCSD calculations for ions of even-number charge. The second-order hyperpolarizability coefficients were found to decrease when the electrons are progressively removed from the system. At higher ionization states, these coefficients become less dispersive as a function of wavelength. The values and even the signs of the γ (2) coefficients were found to depend on the spin of the ionic quantum state. Thus, for Ne+3 and Ne+4, in low-spin states (2 Pu, and 1 Sg, respectively) the sign of γ (2) is positive, whereas in high-spin states (4 Su, and 3 Pg) the sign is negative. The calculated hyperpolarizabilities of multiply ionized atoms relate to experiments on very bright high-order harmonic generation in multiply ionized plasmas.

  17. Equation of state for a partially ionized gas. II.

    PubMed

    Baker, George A

    2003-11-01

    The derivation of equations of state for fluid phases of a partially ionized gas or plasma is addressed from a fundamental point of view. A spherical cellular model is deduced for the hot curve limit (or ideal Fermi gas). Next the Coulomb interactions are added to the spherical cellular model for general ionic charge Z. Then an independent electron model within a Z electron cell plus several many-body effects are employed. Numerical examples of the theory for several elements (H, Li, N, Na, K, Ni, Rb, Pd, Cs, and Er) are reported. These results reduce in various limits of temperature and density to the expected behavior. They display electron, localization-delocalization phase transitions of liquid-gas character. In the higher Z elements, a second possible critical point has been found. The critical pressure, electron density and temperature for the lower-density critical points seem to obey power laws as a function of Z.

  18. Residual-gas-ionization beam profile monitors in RHIC

    SciTech Connect

    Connolly, R.; Fite, J.; Jao, S.; Trabocchi, C.

    2010-05-02

    Four ionization profile monitors (IPMs) are in RHIC to measure vertical and horizontal beam profiles in the two rings. These work by measuring the distribution of electrons produced by beam ionization of residual gas. During the last two years both the collection accuracy and signal/noise ratio have been improved. An electron source is mounted across the beam pipe from the collector to monitor microchannel plate (MCP) aging and the signal electrons are gated to reduce MCP aging and to allow charge replenishment between single-turn measurements. Software changes permit simultaneous measurements of any number of individual bunches in the ring. This has been used to measure emittance growth rates on six bunches of varying intensities in a single store. Also the software supports FFT analysis of turn-by-turn profiles of a single bunch at injection to detect dipole and quadrupole oscillations.

  19. Aerodynamic Effects in Weakly Ionized Gas: Phenomenology and Applications

    SciTech Connect

    Popovic, S.; Vuskovic, L.

    2006-12-01

    Aerodynamic effects in ionized gases, often neglected phenomena, have been subject of a renewed interest in recent years. After a brief historical account, we discuss a selected number of effects and unresolved problems that appear to be relevant in both aeronautic and propulsion applications in subsonic, supersonic, and hypersonic flow. Interaction between acoustic shock waves and weakly ionized gas is manifested either as plasma-induced shock wave dispersion and acceleration or as shock-wave induced double electric layer in the plasma, followed by the localized increase of the average electron energy and density, as well as enhancement of optical emission. We describe the phenomenology of these effects and discuss several experiments that still do not have an adequate interpretation. Critical for application of aerodynamic effects is the energy deposition into the flow. We classify and discuss some proposed wall-free generation schemes with respect to the efficiency of energy deposition and overall generation of the aerodynamic body force.

  20. The Cygnus X region. XVI - The ionized gas behind the dark cloud between the North America and Pelican nebulae

    NASA Astrophysics Data System (ADS)

    Heske, A.; Wendker, H. J.

    1985-07-01

    Radio recombination line observations are presented for the ionized gas at selected positions behind the dark cloud separating the North America and Pelican nebulae. The high angular resolution of about 3 arcmin makes it possible to sample the different structural components. The lines are dominated by ionized gas physically similar to that of the visible nebulae. A further extended background source is identified and briefly discussed in terms of an Ori A-type H II region in the Perseus spiral arm.

  1. Approximate Thermodynamics State Relations in Partially Ionized Gas Mixtures

    SciTech Connect

    Ramshaw, J D

    2003-12-30

    In practical applications, the thermodynamic state relations of partially ionized gas mixtures are usually approximated in terms of the state relations of the pure partially ionized constituent gases or materials in isolation. Such approximations are ordinarily based on an artificial partitioning or separation of the mixture into its constituent materials, with material k regarded as being confined by itself within a compartment or subvolume with volume fraction {alpha}k and possessing a fraction {beta}k of the total internal energy of the mixture. In a mixture of N materials, the quantities {alpha}k and {beta}k constitute an additional 2N--2 independent variables. The most common procedure for determining these variables, and hence the state relations for the mixture, is to require that the subvolumes all have the same temperature and pressure. This intuitively reasonable procedure is easily shown to reproduce the correct thermal and caloric state equations for a mixture of neutral (non-ionized) ideal gases. Here we wish to point out that (a) this procedure leads to incorrect state equations for a mixture of partially ionized ideal gases, whereas (b) the alternative procedure of requiring that the subvolumes all have the same temperature and free electron density reproduces the correct thermal and caloric state equations for such a mixture. These results readily generalize to the case of partially degenerate and/or relativistic electrons, to a common approximation used to represent pressure ionization effects, and to two-temperature plasmas. This suggests that equating the subvolume electron number densities or chemical potentials instead of pressures is likely to provide a more accurate approximation even in nonideal plasma mixtures.

  2. New Automated and High-Throughput Quantitative Analysis of Urinary Ketones by Multifiber Exchange-Solid Phase Microextraction Coupled to Fast Gas Chromatography/Negative Chemical-Electron Ionization/Mass Spectrometry

    PubMed Central

    Pacenti, Marco; Dugheri, Stefano; Traldi, Pietro; Degli Esposti, Filippo; Perchiazzi, Nicola; Franchi, Elena; Calamante, Massimo; Kikic, Ireneo; Alessi, Paolo; Bonacchi, Alice; Salvadori, Edoardo; Arcangeli, Giulio; Cupelli, Vincenzo

    2010-01-01

    The present research is focused on automation, miniaturization, and system interaction with high throughput for multiple and specific Direct Immersion-Solid Phase Microextraction/Fast Gas Chromatography analysis of the urinary ketones. The specific Mass Spectrometry instrumentation, capable of supporting such the automated changeover from Negative Chemical to Electron Ionization mode, as well as the automation of the preparation procedure by new device called MultiFiber Exchange, through change of the fibers, allowed a friendly use of mass spectrometry apparatus with a number of advantages including reduced analyst time and greater reproducibility (2.01–5.32%). The detection limits for the seven ketones were less than 0.004 mg/L. For an innovative powerful meaning in high-throughput routine, the generality of the structurally informative Mass Spectrometry fragmentation patterns together with the chromatographic separation and software automation are also investigated. PMID:20628512

  3. Characterization of fatty acid and triacylglycerol composition in animal fats using silver-ion and non-aqueous reversed-phase high-performance liquid chromatography/mass spectrometry and gas chromatography/flame ionization detection.

    PubMed

    Lísa, Miroslav; Netušilová, Kateřina; Franěk, Lukáš; Dvořáková, Hana; Vrkoslav, Vladimír; Holčapek, Michal

    2011-10-21

    Fatty acid (FA) and triacylglycerol (TG) composition of natural oils and fats intake in the diet has a strong influence on the human health and chronic diseases. In this work, non-aqueous reversed-phase (NARP) and silver-ion high-performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry detection and gas chromatography with flame-ionization detection (GC/FID) and mass spectrometry detection are used for the characterization of FA and TG composition in complex samples of animal fats from fallow deer, red deer, sheep, moufflon, wild boar, cock, duck and rabbit. The FA composition of samples is determined based on the GC/FID analysis of FA methyl esters. In total, 81 FAs of different acyl chain length, double bond (DB) number, branched/linear, cis-/trans- and DB positional isomers are identified. TGs in animal fats contain mainly monounsaturated and saturated FAs. High amounts of branched and trans-FAs are observed in the samples of ruminants. In NARP mode, individual TG species are separated including the separation of trans- and branched TGs. Silver-ion mode provides the separation of TG regioisomers, which enables the determination of their ratios. Great differences in the preference of unsaturated and saturated FAs in the sn-2 position on the glycerol skeleton are observed among individual animal fats. Unsaturated FAs are preferentially occupied in the sn-2 position in all animal samples except for wild boar with the strong preference of saturated FAs in the sn-2 position.

  4. Detection of Extraplanar Diffuse Ionized Gas in M83

    NASA Astrophysics Data System (ADS)

    Boettcher, Erin; Gallagher, J. S., III; Zweibel, Ellen G.

    2017-08-01

    We present the first kinematic study of extraplanar diffuse ionized gas (eDIG) in the nearby, face-on disk galaxy M83 using optical emission-line spectroscopy from the Robert Stobie Spectrograph on the Southern African Large Telescope. We use a Markov Chain Monte Carlo method to decompose the [N ii]λ λ 6548, 6583, Hα, and [S ii]λ λ 6717, 6731 emission lines into H ii region and diffuse ionized gas emission. Extraplanar, diffuse gas is distinguished by its emission-line ratios ([N ii]λ6583/Hα ≳ 1.0) and its rotational velocity lag with respect to the disk ({{Δ }}v=-24 km s-1 in projection). With interesting implications for isotropy, the velocity dispersion of the diffuse gas, σ =96 km s-1, is a factor of a few higher in M83 than in the Milky Way and nearby, edge-on disk galaxies. The turbulent pressure gradient is sufficient to support the eDIG layer in dynamical equilibrium at an electron scale height of {h}z=1 kpc. However, this dynamical equilibrium model must be finely tuned to reproduce the rotational velocity lag. There is evidence of local bulk flows near star-forming regions in the disk, suggesting that the dynamical state of the gas may be intermediate between a dynamical equilibrium and a galactic fountain flow. As one of the first efforts to study eDIG kinematics in a face-on galaxy, this study demonstrates the feasibility of characterizing the radial distribution, bulk velocities, and vertical velocity dispersions in low-inclination systems. Based on observations made with the Southern African Large Telescope (SALT) under program 2015-2-SCI-004 (PI: E. Boettcher).

  5. Ionized gas clouds near the Sagittarius Arm tangent

    NASA Astrophysics Data System (ADS)

    Hou, Li-Gang; Dong, Jian; Gao, Xu-Yang; Han, Jin-Lin

    2017-04-01

    Radio recombination lines (RRLs) are the best tracers of ionized gas. Simultaneous observations of multi-transitions of RRLs can significantly improve survey sensitivity. We conducted pilot RRL observations near the Sagittarius Arm tangent by using the 65-m Shanghai Tian Ma Radio Telescope (TMRT) equipped with broadband feeds and a digital backend. Six hydrogen RRLs (H96 α - H101α) at C band (6289 MHz-7319 MHz) were observed simultaneously toward a sky area of 2° × 1.2° by using on-the-fly mapping mode. These transitions were then stacked together for detection of ionized gas. Star forming complexes G48.6+0.1 and G49.5-0.3 were detected in the integrated intensity map. We found agreements between our measured centroid velocities and previous results for the 21 known HII regions in the mapped area. For more than 80 cataloged HII region candidates without previous RRL measurements, we obtained new RRL spectra at 30 targeted positions. In addition, we detected 25 new discrete RRL sources with spectral S/N > 5 σ, and they were not listed in the catalogs of previously known HII regions. The distances for 44 out of these 55 new RRL sources were estimated.

  6. Earth’s Interaction Region: Plasma-Neutral Interactions in the Weakly Ionized gas of Earth’s High Latitude Upper Atmosphere

    NASA Astrophysics Data System (ADS)

    Thayer, Jeffrey; Hsu, Vicki

    2015-04-01

    The high-latitude regions of Earth’s upper atmosphere are strongly influenced by plasma-neutral interactions. These interactions couple electrodynamic processes of the ionosphere with hydrodynamic processes of the more abundant thermosphere neutral gas, consequently connecting the high-latitude upper atmosphere to distant regions of the geoplasma environment. This produces a complex spatial and temporal interplay of competing processes that results in a myriad of physical and chemical responses and a rich array of neutral and plasma morphologies that constitute the high-latitude thermosphere and ionosphere. The altitude extent from the lower thermosphere to the upper ionosphere (90km - 1000km) can be considered Earth’s space-atmosphere interaction region - likened to the solar chromosphere’s interaction region where radiative processes and hydrodynamic waves from the dense lower atmosphere produce a cold lower boundary that quickly transitions over a few 100 kilometers to neutral and plasma temperatures that are five times hotter. A thousand or more kilometers further in altitude, Earth's upper atmosphere becomes a hot, collisionless, geomagnetically controlled protonosphere whose neutral and plasma population originates from the thermosphere and ionosphere. A grand challenge in the study of Earth’s interaction region is how the collision-dominated thermosphere/ionosphere system exchanges energy, mass and momentum with the collisionless magnetosphere. This talk will focus primarily on collision-dominated processes of the high-latitude ionosphere and the electromagnetic energy transfer processes that lead to frictional heating of ions and neutrals, and plasma instability phenomenon that leads to extreme electron heating. Observations of the ionosphere response to these processes will be illustrated using incoherent scatter radar measurements. Relevance to the solar chromosphere will be identified where appropriate and outstanding issues in Earth

  7. Capillary atmospheric pressure electron capture ionization (cAPECI): a highly efficient ionization method for nitroaromatic compounds.

    PubMed

    Derpmann, Valerie; Mueller, David; Bejan, Iustinian; Sonderfeld, Hannah; Wilberscheid, Sonja; Koppmann, Ralf; Brockmann, Klaus J; Benter, Thorsten

    2014-03-01

    We report on a novel method for atmospheric pressure ionization of compounds with elevated electron affinity (e.g., nitroaromatic compounds) or gas phase acidity (e.g., phenols), respectively. The method is based on the generation of thermal electrons by the photo-electric effect, followed by electron capture of oxygen when air is the gas matrix yielding O2(-) or of the analyte directly with nitrogen as matrix. Charge transfer or proton abstraction by O2(-) leads to the ionization of the analytes. The interaction of UV-light with metals is a clean method for the generation of thermal electrons at atmospheric pressure. Furthermore, only negative ions are generated and neutral radical formation is minimized, in contrast to discharge- or dopant assisted methods. Ionization takes place inside the transfer capillary of the mass spectrometer leading to comparably short transfer times of ions to the high vacuum region of the mass spectrometer. This strongly reduces ion transformation processes, resulting in mass spectra that more closely relate to the neutral analyte distribution. cAPECI is thus a soft and selective ionization method with detection limits in the pptV range. In comparison to standard ionization methods (e.g., PTR), cAPECI is superior with respect to both selectivity and achievable detection limits. cAPECI demonstrates to be a promising ionization method for applications in relevant fields as, for example, explosives detection and atmospheric chemistry.

  8. Stellar and ionized gas kinematics of the interacting Seyfert 1.9 galaxy NGC 2992

    NASA Astrophysics Data System (ADS)

    García-Lorenzo, B.; Arribas, S.; Mediavilla, E.

    2001-11-01

    Integral field spectroscopy in the central 16''x 12'' (2.4 kpc x 1.8 kpc, if H0 = 75 km s-1 Mpc-1) of the Seyfert 1.9 galaxy NGC 2992 has been obtained using the fibre system INTEGRAL. The data are mainly used to study the stellar and ionized gas kinematics. In spite of the photometric disruptions in the outer parts (r > 6 kpc) produced by the interaction with its close companion (NGC 2993), the present stellar velocity field shows regular rotation. The ionized gas presents several kinematically distinct components. Apart from the outflowing component already reported by other authors, we found an additional (high ionization) kinematic component which seems to be associated with the boundaries of the figure-of-eight-shaped emission detected in the 6 cm radio map. We locate the hidden nucleus in the apex of the biconical structure defined by the [O iii] emission, coincident with the outflow origin and with the center of the dust lane. We do not find any clear evidence of direct influence of the interaction in the kinematics of the stars or the ionized gas in the circumnuclear region of NGC 2992.

  9. Kinematics and ionization of extended gas in active galaxies. III. The extranuclear properties of NGC 1068

    SciTech Connect

    Baldwin, J.A.; Wilson, A.S.; Whittle, M.

    1987-08-01

    The kinematic and ionization structure of the extranuclear gas of the Seyfert 2 galaxy NGC 1068 has been investigated using a grid of 28 high- and seven low-dispersion long-slit spectra. The velocity field of most of the gas more than 15 arcsec from the nucleus is well described by a rotating disk with an approximately flat rotation curve. The kinematic line of nodes coincides with the major axis of the outermost continuum light, and the disk inclination derived from the axial ratio of the outer isophotes and the kinematic fit are broadly consistent. The progressive change of the position angle of the major axes of the brighter isophotes are evidently due to a superposition of oval or barlike distortions in the galactic plane. The observed ionization structure of the gas can be understood as a mixture of two disk components projected on top of each other. Much of the ionization pattern in the other disk may result from partial beaming of the ionizing continuum radiation as it escapes from the nucleus. 60 references.

  10. IONIZED GAS IN THE FIRST 10 kpc OF THE INTERSTELLAR GALACTIC HALO: METAL ION FRACTIONS

    SciTech Connect

    Howk, J. Christopher; Consiglio, S. Michelle E-mail: smconsiglio@ucla.edu

    2012-11-10

    We present direct measures of the ionization fractions of several sulfur ions in the Galactic warm ionized medium (WIM). We obtained high-resolution ultraviolet absorption-line spectroscopy of post-asymptotic giant branch stars in the globular clusters Messier 3 [(l, b) = (42.{sup 0}2, +78.{sup 0}7), d = 10.2 kpc, and z = 10.0 kpc] and Messier 5 [(l, b) = (3.{sup 0}9, +46.{sup 0}8), d = 7.5 kpc, and z = +5.3 kpc] with the Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer to measure, or place limits on, the column densities of S I, S II, S III, S IV, S VI, and H I. These clusters also house millisecond pulsars, whose dispersion measures give an electron column density from which we infer the H II column in these directions. We find fractions of S{sup +2} in the WIM for the M 3 and M 5 sight lines x(S{sup +2}) {identical_to} N(S{sup +2})/N(S) = 0.33 {+-} 0.07 and 0.47 {+-} 0.09, respectively, with variations perhaps related to location. With negligible quantities of the higher ionization states, we conclude that S{sup +} and S{sup +2} account for all of the S in the WIM. We extend the methodology to study the ion fractions in the warm and hot ionized gas of the Milky Way, including the high ions Si{sup +3}, C{sup +3}, N{sup +4}, and O{sup +5}. The vast majority of the Galactic ionized gas is warm (T {approx} 10{sup 4} K) and photoionized (the WIM) or very hot (T > 4 Multiplication-Sign 10{sup 5} K) and collisionally ionized. The common tracer of ionized gas beyond the Milky Way, O{sup +5}, traces <1% of the total ionized gas mass of the Milky Way.

  11. In-gas-cell laser ionization studies of plutonium isotopes at IGISOL

    NASA Astrophysics Data System (ADS)

    Pohjalainen, I.; Moore, I. D.; Kron, T.; Raeder, S.; Sonnenschein, V.; Tomita, H.; Trautmann, N.; Voss, A.; Wendt, K.

    2016-06-01

    In-gas-cell resonance laser ionization has been performed on long-lived isotopes of Pu at the IGISOL facility, Jyväskylä. This initiates a new programme of research towards high-resolution optical spectroscopy of heavy actinide elements which can be produced in sufficient quantities at research reactors and transported to facilities elsewhere. In this work a new gas cell has been constructed for fast extraction of laser-ionized elements. Samples of 238-240,242Pu and 244Pu have been evaporated from Ta filaments, laser ionized, mass separated and delivered to the collinear laser spectroscopy station. Here we report on the performance of the gas cell through studies of the mass spectra obtained in helium and argon, before and after the radiofrequency quadrupole cooler-buncher. This provides valuable insight into the gas phase chemistry exhibited by Pu, which has been additionally supported by measurements of ion time profiles. The resulting monoatomic yields are sufficient for collinear laser spectroscopy. A gamma-ray spectroscopic analysis of the Pu samples shows a good agreement with the assay provided by the Mainz Nuclear Chemistry department.

  12. A Pre-ionization System to Limit Neutral Gas in a Compact Toroid Injector

    NASA Astrophysics Data System (ADS)

    Allfrey, Ian; Roche, Thomas; Matsumoto, Tadafumi; Garate, Eusebio; Gota, Hiroshi; Asai, Tomohiko; the TAE Team

    2016-10-01

    Fusion plasmas require long lifetimes and high temperatures, both of which are limited by particle loss, among other factors. Therefore, refueling a long-lived advanced beam-driven field-reversed configuration (FRC) plasma in C-2U is necessary, and injecting a supersonic compact toroid (CT) is an effective means of introducing particles into the FRC core. However, neutral gas that trails the CT into the target chamber cools the FRC. Pre-ionization (PI) system assists the break down between electrodes of the CT injector (CTI), so the amount of introduced gas can be lowered by up to a factor of two, effectively increasing the ionization fraction; thus, reducing the amount of neutral gas in the system. Additionally, the PI decreases the delay in CTI breakdown so a highly reproducible operation is achievable. The PI system consists of a fast, high voltage, pulse discharge circuit coupled to a Teflon insulated semi-rigid coaxial cable inserted into the CTI. System details and experimental data will be presented, in addition to issues such as the introduction of impurities and pre-ionizer lifetime.

  13. Comparison of Atmospheric Pressure Ionization Gas Chromatography-Triple Quadrupole Mass Spectrometry to Traditional High-Resolution Mass Spectrometry for the Identification and Quantification of Halogenated Dioxins and Furans.

    PubMed

    Organtini, Kari L; Haimovici, Liad; Jobst, Karl J; Reiner, Eric J; Ladak, Adam; Stevens, Douglas; Cochran, Jack W; Dorman, Frank L

    2015-08-04

    The goal of this study was to qualify gas chromatography coupled to atmospheric pressure ionization tandem mass spectrometry (APGC-MS/MS) as a reliable and valid technique for analysis of halogenated dioxins and furans that could be used in place of more traditional gas chromatography coupled to high-resolution mass spectrometry (GC-HRMS) analysis. A direct comparison of the two instrumental techniques was performed. APGC-MS/MS system sensitivity was demonstrated to be on the single femtogram level. The APGC-MS/MS analysis also demonstrated method detection limits (MDLs) in both sediment and fish that were 2-18 times lower than those determined for the GC-HRMS. Inlet conditions were established to prevent issues with sample carry-over, due largely to the enhanced sensitivity of this technique. Additionally, this work utilized direct injection for sample introduction through the split/splittless inlet. Finally, quantification of both sediment and fish certified reference materials were directly compared between the APGC-MS/MS and GC-HRMS. The APGC-MS/MS performed similarly to, if not better than, the GC-HRMS instrument in the analysis of these samples. This data is intended to substantiate APGC-MS/MS as a comparable technique to GC-HRMS for the analysis of dioxins and furans.

  14. INTEGRAL Field Spectroscopy of the Extended Ionized Gas in Arp 220

    NASA Astrophysics Data System (ADS)

    Colina, Luis; Arribas, Santiago; Clements, David

    2004-02-01

    Integral field optical spectroscopy with the INTEGRAL system has been used to investigate for the first time the two-dimensional kinematic and ionization properties of the extended, warm, ionized gas in Arp 220 over an area of 75.0"×40.0" (i.e., 28×15 kpc). The structure of the ionized gas is divided into well-identified regions associated with the X-ray-emitting plumes and extended lobes, previously studied in detail by McDowell and collaborators. The overall ionization state of the warm gas in the plumes and lobes, as traced by the [N II]/Hα line, is consistent with high-velocity shocks expanding in a neutral ambient medium. Changes in the ionization state of the gas along the major axis of the plumes are detected, in particular in the outer regions of the northwestern plume, where the transition between the main stellar body of the galaxy and a broad, low surface brightness tidal tail is located. If the plumes are produced by a starburst-driven galactic wind, the efficiency in the conversion of mechanical to radiation energy is a factor of at least 10 smaller than in galactic winds developed in edge-on spiral galaxies with well-defined rotation and axis of outflow. The kinematic properties of the lobes, with an average velocity of +8 km s-1 (east lobe) and -79 km s-1 (west lobe), are to a first order in agreement with the predictions of the merger scenario, according to which the lobes are tidally induced gas condensations produced during the merging process. The largest velocity gradients of 50 km s-1 kpc-1 and velocity deviations of up to +280 and -320 km s-1 from the systemic velocity are associated not with the plumes but with the outer stellar envelope and broad tidal tails at distances of up to 7.5 kpc, indicating that the large-scale kinematics of the extended ionized gas in Arp 220 is most likely dominated by the tidally induced motions, and not by galactic winds associated with nuclear starbursts. Based on observations with the William Herschel

  15. The Ionization of the Warm Gas in Early-type Galaxies and Its UV Upturn

    NASA Astrophysics Data System (ADS)

    Yan, Renbin; Blanton, Michael R.

    2015-03-01

    It has long been known that the majority of early-type galaxies contain warm ionized gas producing optical emission lines. These warm ionized gas are spatially extended to kpc scales. Their line ratios satisify the criteria of Low-ionization Nuclear Emission-line Regions (LINERs) on all major line-ratio diagnostic diagrams. However, their ionization mechanism has been hotly debated. Multiple ionization mechanisms can produce the same kind of line ratios, including photoionization by a central AGN, photoionization by hot evolved stars (e.g. post-AGB stars), collisional ionization by fast shocks, photoionization by hot X-ray emitting gas, and conductive heating or turbulent mixing. Therefore, determining the ionization mechanism requires other information.

  16. Laser ionization and radiofrequency sustainment of high- pressure seeded plasmas

    NASA Astrophysics Data System (ADS)

    Kelly, Kurtis Lester

    2001-10-01

    The feasibility of using a low-ionization potential organic gas to initiate a high-pressure plasma discharge is examined. Laser photoionization of the organic gas creates a high-density initial condition that eliminates the need for capacitive breakdown to form the plasma. The seed gas, tetrakis(dimethylamino)ethylene, has an ionization potential of 6.1 eV and is ionized by an ultraviolet laser through 6.4 eV photon absorption forming a plasma column inside a vacuum chamber. The plasma absorbs power through collisional damping of the induced 13.56 MHz radiofrequency wave fields. The laser initiation of 2-6 mTorr of the seed gas in 1-150 Torr of argon is accomplished producing steady-state plasma densities of ne >= 1012 cm-3 in a volume of 300-500 cm3 with radiofrequency power densities of 3-10 Watts/cm3. Electron density measurements are taken using a millimeter wave interferometer. The dependence of the antenna radiation resistance and reactance on the plasma density and neutral gas pressure is measured, examined and compared to a transformer coupled equivalent circuit and to a computer model. The coupling can be described by propagation and absorption of the fields into a lossy plasma medium. Antenna design is aided by understanding the radial absorption profile of the inductive radiofrequency fields, and how these fields are excited by various antenna designs. It is found that the azimuthally symmetric helical coil excites the wave fields most conducive to sustaining the plasma at high pressure. The two-body recombination coefficient of the organic seed gas and its optimum partial pressure when mixed with argon at 50-150 Torr are experimentally determined. Particle losses and power requirements for maintaining the discharge are estimated by examining diffusion, two-body and three-body recombination processes. It is found that recombination losses play a dominant role at these high pressures which places an upper bound on the density that is achievable with the 2

  17. Chemical Abundances and Properties of the Ionized Gas in NGC 1705

    NASA Astrophysics Data System (ADS)

    Annibali, F.; Tosi, M.; Pasquali, A.; Aloisi, A.; Mignoli, M.; Romano, D.

    2015-11-01

    We obtained [O iii] narrow-band imaging and multi-slit MXU spectroscopy of the blue compact dwarf (BCD) galaxy NGC 1705 with FORS2@VLT to derive chemical abundances of planetary nebulae and H ii regions and, more in general, to characterize the properties of the ionized gas. The auroral [O iii]λ 4363 line was detected in all but 1 of the 11 analyzed regions, allowing for a direct estimate of their electron temperature. The only object for which the [O iii]λ 4363 line was not detected is a possible low-ionization PN, the only one detected in our data. For all the other regions, we derived the abundances of nitrogen, oxygen, neon, sulfur, and argon out to ˜1 kpc from the galaxy center. We detect for the first time in NGC 1705 a negative radial gradient in the oxygen metallicity of -0.24+/- 0.08 dex kpc-1. The element abundances are all consistent with values reported in the literature for other samples of dwarf irregular and BCD galaxies. However, the average (central) oxygen abundance, 12+{log}({{O}}/{{H}})=7.96+/- 0.04, is ˜0.26 dex lower than previous literature estimates for NGC 1705 based on the [O iii]λ 4363 line. From classical emission line diagnostic diagrams, we exclude a major contribution from shock excitation. On the other hand, the radial behavior of the emission line ratios is consistent with the progressive dilution of radiation with increasing distance from the center of NGC 1705. This suggests that the strongest starburst located within the central ˜150 pc is responsible for the ionization of the gas out to at least ˜1 kpc. The gradual dilution of the radiation with increasing distance from the center reflects the gradual and continuous transition from the highly ionized H ii regions in the proximity of the major starburst into the diffuse ionized gas.

  18. X-Ray Gas Ionization Studies with a Single-Walled Nanotube (SWNT) Sensor

    NASA Astrophysics Data System (ADS)

    Asare Agyapong, Paul

    Due to their high surface areas, Single-Walled Nanotubes (SWNTs) and their thin films, are wonderful media for sensing applications. To establish the radiation sensing mechanism and limits of an SWNT ion sensor, we performed gas ionization studies with an Amptek Mini-x x-ray source. We irradiated the sensor under varying conditions of source to sensor distance, gas concentration, and fill-gas type. The mechanism of the SWNT sensor, which is responsive to the gaseous ions the radiation generates, resembles that of conventional gas filled detectors with reduced power requirements. Additionally, the small size of the sensor favors the development of miniaturized and portable radiation detectors which retain high sensitivity. Sensor responsiveness to radiation, such as x-rays and gamma rays, can be maximized by enclosure in various noble gasses, which are chemically non-reactive, have small magnitudes of ionization potentials, and readily produce charged species when subjected to radiation. When encapsulated with gaseous argon, the SWNT sensors were shown to be up to 246% more sensitive to 1.34 Sv dose of 20 keV x-rays than sensors enclosed in air. The dependence of the sensors' electrical response to fill-gas material helps to push the minimum detection capabilities of this technology to new limits. Optimal performance may result through the use of more readily ionized gasses such as xenon or penning gas mixtures. Through Monte Carlo simulation and PIN diode measurements, the x-ray source intensity was determined and used to establish exposure rates for each test case. These sensors display changes in resistivity when exposed to charged ions, with no direct response to x-rays, gamma rays, and neutron radiation particles.

  19. The Impact of Diffuse Ionized Gas on Emission-line Ratios and Gas Metallicity Measurements

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Yan, Renbin; MaNGA Team

    2016-01-01

    Diffuse Ionized Gas (DIG) is prevalent in star-forming galaxies. Using a sample of galaxies observed by MaNGA, we demonstrate how DIG in star-forming galaxies impact the measurements of emission line ratios, hence the gas-phase metallicity measurements and the interpretation of diagnostic diagrams. We demonstrate that emission line surface brightness (SB) is a reasonably good proxy to separate HII regions from regions dominated by diffuse ionized gas. For spatially-adjacent regions or regions at the same radius, many line ratios change systematically with emission line surface brightness, reflecting a gradual increase of dominance by DIG towards low SB. DIG could significantly bias the measurement of gas metallicity and metallicity gradient. Because DIG tend to have a higher temperature than HII regions, at fixed metallicity DIG displays lower [NII]/[OII] ratios. DIG also show lower [OIII]/[OII] ratios than HII regions, due to extended partially-ionized regions that enhance all low-ionization lines ([NII], [SII], [OII], [OI]). The contamination by DIG is responsible for a substantial portion of the scatter in metallicity measurements. At different surface brightness, line ratios and line ratio gradients can differ systematically. As DIG fraction could change with radius, it can affect the metallicity gradient measurements in systematic ways. The three commonly used strong-line metallicity indicators, R23, [NII]/[OII], O3N2, are all affected in different ways. To make robust metallicity gradient measurements, one has to properly isolate HII regions and correct for DIG contamination. In line ratio diagnostic diagrams, contamination by DIG moves HII regions towards composite or LINER-like regions.

  20. Central 300 PC of the Galaxy Probed by the Infrared Spectra of H_3^+ and Co: I. Predominance of Warm and Diffuse Gas and High H_2 Ionization Rate

    NASA Astrophysics Data System (ADS)

    Oka, Takeshi; Geballe, Thomas R.; Goto, Miwa; Usuda, Tomonori; Indriolo, Nick

    2016-06-01

    A low-resolution 2.0-2.5 μm survey of ˜500 very red point-like objects in the Central Molecular Zone (CMZ) of our Galaxy, initiated in 2008, has revealed many new bright objects with featureless spectra that are suitable for high resolution absorption spectroscopy of H_3^+ and CO. We now have altogether 48 objects mostly close to the Galactic plane located from 142 pc to the west of Sgr A* to 120 pc east allowing us to probe dense and diffuse gas by H_3^+ and dense gas by CO. Our observations demonstrate that the warm (˜250 K) and diffuse (≤100 cm-3) gas with a large column length (≥30 pc) initially observed toward the brightest star in the CMZ, GCS3-2 of the Quintuplet Cluster, exists throughout the CMZ with the surface filling factor of ˜ 100% dominating the region. The column densities of CO in the CMZ are found to be much less than those in the three foreground spiral arms except in the directions of Sgr B and Sgr E complexes and indicate that the volume filling factor of dense clouds of 10% previously estimated is a gross overestimate for the front half of the CMZ. Nevertheless the predominance of the newly found diffuse molecular gas makes the term "Central Molecular Zone" even more appropriate. The ultra-hot X-rays emitting plasma which some thought to dominate the region must be non existent except near the stars and SNRs. Recently the H_2 fraction f(H_2) in diffuse gas of the CMZ has been reported to be ˜0.6. If we use this value, the cosmic ray H_2 ionization rate ζ of a few times 10-15 s-1 reported earlier^b on the assumption of f(H_2)=1 needs to be increased by a factor of ˜3 since the value is approximately inversely proportional to f(H_2)^2. Geballe, T. R., Oka, T., Lambridges, E., Yeh, S. C. C., Schlegelmilch, B., Goto, M., Westrick, C. W., WI07 at the 70th ISMS, Urbana, IL, USA,2015 Oka, T., Geballe, T. R., Goto, M., Usuda, T., McCall, B. J. 2005, ApJ, 632, 882 Le Petit, F., Ruaud, M., Bron, E., Godard, B., Roueff, E., Languignon, D., Le

  1. A VUV Photoionization and Ab Initio Determination of the Ionization Energy of a Gas-Phase Sugar (Deoxyribose).

    PubMed

    Ghosh, Debashree; Golan, Amir; Takahashi, Lynelle K; Krylov, Anna I; Ahmed, Musahid

    2012-01-05

    The ionization energy of gas-phase deoxyribose was determined using tunable vacuum ultraviolet synchrotron radiation coupled to an effusive thermal source. Adiabatic and vertical ionization energies of the ground and first four excited states of α-pyranose, the structure that dominates in the gas phase, were calculated using high-level electronic structure methods. An appearance energy of 9.1(±0.05) eV was recorded, which agrees reasonably well with a theoretical value of 8.8 eV for the adiabatic ionization energy. A clear picture of the dissociative photoionization dynamics of deoxyribose emerges from the fragmentation pattern recorded using mass spectrometry and from ab initio molecular dynamics calculations. The experimental threshold 9.4 (±0.05) eV for neutral water elimination upon ionization is captured well in the calculations, and qualitative insights are provided by molecular orbital analysis and molecular dynamics snapshots along the reaction coordinate.

  2. Analysis of aldehydes in beer by gas-diffusion microextraction: characterization by high-performance liquid chromatography-diode-array detection-atmospheric pressure chemical ionization-mass spectrometry.

    PubMed

    Gonçalves, Luís Moreira; Magalhães, Paulo Jorge; Valente, Inês Maria; Pacheco, João Grosso; Dostálek, Pavel; Sýkora, David; Rodrigues, José António; Barros, Aquiles Araújo

    2010-06-11

    In this work, a recently developed extraction technique for sample preparation aiming the analysis of volatile and semi-volatile compounds named gas-diffusion microextraction (GDME) is applied in the chromatographic analysis of aldehydes in beer. Aldehydes-namely acetaldehyde (AA), methylpropanal (MA) and furfural (FA)-were simultaneously extracted and derivatized with 2,4-dinitrophenylhydrazine (DNPH), then the derivatives were separated and analyzed by high-performance liquid chromatography with spectrophotometric detection (HPLC-UV). The identity of the eluted compounds was confirmed by high-performance liquid chromatography-atmospheric pressure chemical ionization-mass-spectrometry detection in the negative ion mode (HPLC-APCI-MS). The developed methodology showed good repeatability (ca. 5%) and linearity as well as good limits of detection (AA-12.3, FA-1.5 and MA 5.4microgL(-1)) and quantification (AA-41, FA-4.9 and MA 18microgL(-1)); it also appears to be competitive in terms of speed and cost of analysis.

  3. Analysis of persistent organic pollutants at sub-femtogram levels using a high-power picosecond laser for multiphoton ionization in conjunction with gas chromatography/time-of-flight mass spectrometry.

    PubMed

    Matsui, Taiki; Fukazawa, Kodai; Fujimoto, Masatoshi; Imasaka, Totaro

    2012-01-01

    A low-energy, high-repetition-rate picosecond laser (40 µJ, 20 kHz, 258 nm) was used for multiphoton ionization (MPI) in gas chromatography/time-of-flight mass spectrometry to quantitatively determine dioxins (DXNs) and polycyclic aromatic hydrocarbons (PAHs). The sensitivity of the technique was compared with that obtained using a high-energy, low-repetition-rate femtosecond laser (86 µJ, 1 kHz, 261 nm). The limits of detection (LODs) for the picosecond laser were several femtograms for chlorinated DXNs with low numbers of chloro substituents, and were several times lower than values obtained using a femtosecond laser, although the LODs were increased, reaching values that were nearly identical to those for the femtosecond laser for octachlorodibenzo-p-dioxin (octaCDD) and octachlorodibenzofuran (octaCDF). The LODs were also measured for 16 PAHs specified by the United States Environmental Protection Agency; the values for half of these compounds were at sub-femtogram levels. The procedure was used to analyze a surface-water sample collected from a river.

  4. High Velocity Gas Gun

    NASA Technical Reports Server (NTRS)

    1988-01-01

    A video tape related to orbital debris research is presented. The video tape covers the process of loading a High Velocity Gas Gun and firing it into a mounted metal plate. The process is then repeated in slow motion.

  5. High Velocity Gas Gun

    NASA Technical Reports Server (NTRS)

    1988-01-01

    A video tape related to orbital debris research is presented. The video tape covers the process of loading a High Velocity Gas Gun and firing it into a mounted metal plate. The process is then repeated in slow motion.

  6. Modeling of gas ionization and plasma flow in ablative pulsed plasma thrusters

    NASA Astrophysics Data System (ADS)

    Huang, Tiankun; Wu, Zhiwen; Liu, Xiangyang; Xie, Kan; Wang, Ningfei; Cheng, Yue

    2016-12-01

    A one-dimensional model to study the gas ionization and plasma flow in ablative pulsed plasma thrusters(APPTs) is established in this paper. The discharge process of the APPT used in the LES-6 satellite is simulated to validate the model. The simulation results for the impulse bit and propellant utilization give values of 29.05 μN s and 9.56%, respectively, which are in good agreement with experimental results. To test the new ionization sub-model, the discharge process of a particular APPT, XPPT-1, is simulated, and a numerical result for the propellant utilization of 62.8% is obtained, which also agrees well with experiment. The gas ionization simulation results indicate that an APPT with a lower average propellant ablation rate and higher average electric field intensity between electrodes should have higher propellant utilization. The plasma density distribution between the electrodes of APPTs can also be obtained using the new model, and the numerical results show that the plasma generation and flow are discontinuous, which is in good agreement with past experimental results of high-speed photography. This model provides a new tool with which to study the physical mechanisms of APPTs and a reference for the design of high-performance APPTs.

  7. Plasma channel created by ionization of gas by a surface wave

    SciTech Connect

    Konovalov, V. N.; Kuz’min, G. P.; Minaev, I. M. Rukhadze, A. A.; Tikhonevich, O. V.

    2015-09-15

    Conditions for gas ionization in the field of a slow surface wave excited by a microwave source are considered. The gas ionization rate and the plasma density distribution over the radius of the discharge tube were studied by the optical method. The experiments were conducted in a dielectric tube with a radius much smaller than the tube length, the gas pressure being ∼1–3 Torr. It is shown that the stationary distribution of the plasma density is determined by diffusion processes.

  8. A switchable reagent ion high resolution time-of-flight chemical ionization mass spectrometer for real-time measurement of gas phase oxidized species: characterization from the 2013 Southern Oxidant and Aerosol Study

    NASA Astrophysics Data System (ADS)

    Brophy, P.; Farmer, D. K.

    2015-03-01

    A novel configuration of the Aerodyne high resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) as a switchable reagent ion (SRI) HR-TOF-CIMS is presented and described along with data collected at the Southern Oxidant and Aerosol Study (SOAS) during the summer of 2013. The calibration system and reduced pressure gas-phase inlet are characterized. The average limit of detection and limit of quantification for formic acid during SOAS are 82 and 863 ppt, respectively, corresponding to an average sensitivity of 13 ± 5 Hz ppt-1. Hourly background determinations and calibrations are shown to be essential for tracking instrument performance and accurately quantifying formic acid. Maximum daytime formic acid concentrations of 10 ppb are reported during SOAS, and a strong diel cycle is observed leading to night time concentrations below the limit of quantification. Other species presented exhibit diel behavior similar to formic acid. The concept of the mass defect enhancement plot and the use of signal-to-noise are described in detail as a method for investigating HR-TOF-CIMS spectra in an effort to reduce data complexity.

  9. A switchable reagent ion high resolution time-of-flight chemical ionization mass spectrometer for real-time measurement of gas phase oxidized species: characterization from the 2013 southern oxidant and aerosol study

    NASA Astrophysics Data System (ADS)

    Brophy, P.; Farmer, D. K.

    2015-07-01

    A novel configuration of the Aerodyne high resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) as a switchable reagent ion (SRI) HR-TOF-CIMS is presented and described along with data collected at the Southern Oxidant and Aerosol Study (SOAS) during the summer of 2013. The calibration system and reduced pressure gas phase inlet are characterized. The average limit of detection and limit of quantification for formic acid during SOAS are 82 and 863 ppt, respectively, corresponding to an average sensitivity of 13 ± 5 Hz ppt-1. Hourly background determinations and calibrations are shown to be essential for tracking instrument performance and accurately quantifying formic acid. Maximum daytime formic acid concentrations of 10 ppb are reported during SOAS, and a strong diel cycle is observed leading to nighttime concentrations below the limit of quantification. Other species presented exhibit diel behavior similar to formic acid. The concept of the mass defect enhancement plot and the use of signal-to-noise are described in detail as a method for investigating HR-TOF-CIMS spectra in an effort to reduce data complexity.

  10. Highly-ionized species in the interstellar medium

    NASA Technical Reports Server (NTRS)

    Black, J. H.; Hartmann, L. W.; Raymond, J. C.; Dupree, A. K.

    1980-01-01

    Interstellar absorption lines have been observed toward 25 stars with the International Ultraviolet Explorer satellite. Results are presented for observations of interstellar lines of C III, C IV, N V, Si III, and Si IV. Strong lines of Si IV or C IV are seen toward 11 stars. The strengths of these lines are inconsistent with their formation in the same hot gas responsible for the interstellar O IV lines observed with the Copernicus ultraviolet spectrometer. Comparison with simple models of the ionization structures of H II regions around hot stars suggests that the observed column densities of Si III, Si IV, and C IV are in harmony with those expected in normal photoionized nebulae. The line of sight to HD 93250, and O3 V star near Eta Carinae, passes through highly ionized gas that shows features spanning 250 km/s in radial velocity. Stellar wind velocities are presented for 21 of the stars observed in this survey of interstellar absorption lines.

  11. High-throughput analysis of bergamot essential oil by fast solid-phase microextraction-capillary gas chromatography-flame ionization detection.

    PubMed

    Tranchida, Peter Quinto; Presti, Maria Lo; Costa, Rosaria; Dugo, Paola; Dugo, Giovanni; Mondello, Luigi

    2006-01-20

    The advantages of using a narrow-bore column in headspace solid-phase microextraction-gas chromatographic (HS-SPME-GC) analysis are investigated. An automated rapid HS-SPME-GC method for the determination of volatile compounds in a complex sample (bergamot essential oil) was developed. A low-capacity (7 microm) SPME fibre was employed, enabling a short equilibration time (15 min). The absorbed volatile compounds were then separated in 12.5 min on a 10 m x 0.1 mm I.D. capillary. The fast GC method was characterized by relatively moderate GC parameters (head pressure: 173 kPa; temperature program rate: 12 degrees C/min). The employment of the low-capacity fibre also suited the reduced sample capacity of the capillary employed, hence column overloading was avoided. Analytical repeatibility was determined in terms of retention times (maximum RSD: 0.32%) and peak areas (maximum RSD: 9.80%). The results obtained were compared to those derived from a conventional HS-SPME-GC (a 30 microm SPME fibre and 0.25 mm I.D. capillary were used) application on the same sample. In this respect, a great reduction of analytical time was obtained both with regard to the conventional SPME equilibration and GC run times, which both required 50 min. Peak resolution was altogether comparable in both applications. Although a slight loss in terms of sensitivity was observed in the rapid approach (generally within the 25-50% range), this did not impair the detection of all peaks of interest. Finally, the selectivities of the 30 and 7 microm fibres were evaluated and, as expected, these were in good agreement.

  12. Study of the surface ionization detector for gas chromatography.

    PubMed

    Li, Weiwei; Wu, Dapeng; Chen, Shiheng; Peng, Hong; Guan, Yafeng

    2011-09-23

    The structure of the surface ionization detector (SID) and the operation parameters of GC-SID were investigated to reduce peak tailing and to enhance sensitivity. The performances of the GC-SID, including its repeatability, linearity, sensitivity, selectivity, and tolerance towards water vapor, were evaluated systematically. Compared with nitrogen-phosphorus detector (NPD), the SID was able to detect fg level triethylamine, and selectively respond to alkylamines, some anilines, and some nitrogen heterocyclic compounds. Among alkylamines, the SID sensitivity to diisobutylamine was rather small. Even so, it was also still 10 times higher than that on NPD. The SID selectivity, defined as the sensitivity ratio between triethylamine and various tested non-nitrogen compounds, was higher than 10(6). It was found that the SID is highly tolerant towards water vapor, allowing direct injection of water sample. Finally, the GC-SID was applied to directly measure trace amines in headspace gases of rotted meat and trace simazine in tap water. The SID sensitivity to simazine was proven to be 5 times higher than that on flame ionization detector (FID). This study suggests that the SID is a promising GC detector. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Aerodynamic Effects in Weakly Ionized Gas: Phenomenology and Applications

    NASA Astrophysics Data System (ADS)

    Popovic, Svetozar

    2006-10-01

    Successful application of gas discharges in aerodynamics requires their efficient generation, sustaining and control at supersonic or hypersonic flow conditions. Wall-free plasma formations that meet the requirements may then act as time-controlled and space-localized actuators to modify the flow. Potential candidates for this challenging task are plasmas contained in open or linear-cavity microwave field structures. We present and discuss direct observations of aerodynamic effects activated or modified by wall-free discharges. Further, we compare two generic types of wall-free discharges. First group, applicable for inlet-type structures, consists of a periodic series of microwave-induced plasmoids generated in a linear cavity, using the outgoing wave from a microwave antenna and the reflected wave from a nearby on-axis concave reflector. The plasmoids are spaced at half-wavelength separations according to the standing-wave pattern. The plasmoids are enhanced by an ``effective focusing'' in the near field of the antenna (Fresnel region) as a result of diffraction effects and mode structure. Second group, applicable to supersonic and hypersonic boundary layers, are the surface microwave discharges enhanced by a structure of Hertz dipoles. Standard microwave discharge phenomenology, such as microwave breakdown, mode structure and plasma parameters, is revisited to present a quantitative interpretation of the observed effects. Special attention is given to complex phenomena specific to flow-plasma interaction (double electric layers, ionization waves, instabilities), which provide the physical basis for localized heating in the aerodynamic flow.

  14. HIGH PRESSURE GAS REGULATOR

    DOEpatents

    Ramage, R.W.

    1962-05-01

    A gas regulator operating on the piston and feedback principle is described. The device is particularly suitable for the delicate regulation of high pressure, i.e., 10,000 psi and above, gas sources, as well as being perfectly adaptable for use on gas supplies as low as 50 psi. The piston is adjustably connected to a needle valve and the movement of the piston regulates the flow of gas from the needle valve. The gas output is obtained from the needle valve. Output pressure is sampled by a piston feedback means which, in turn, regulates the movement of the main piston. When the output is other than the desired value, the feedback system initiates movement of the main piston to allow the output pressure to be corrected or to remain constant. (AEC)

  15. Ionized gas pressure correlates with star formation intensity in nearby starbursts

    NASA Astrophysics Data System (ADS)

    Jiang, Tianxing; Malhotra, Sangeeta; Yang, Huan

    2016-06-01

    We estimate the electron density of the ionized gas and thus the thermal pressure in HII regions; and compare that to the SFR (star formation rate) surface density for a combined sample of about 40 green peas and Lyman Break Analogs at z < 0.30. The electron density of the ionized gas is measured from sulfur line ratio ([SII] 6716 / 6731). We find that the SFR surface density is correlated with the electron density and the thermal pressure in HII regions for the star-forming galaxies with SFR surface density above a certain threshold. This work shows quantitatively the correlation between SFR surface density and electron density and that between SFR surface density and the thermal pressure in HII regions for the nearby starburst galaxies. This is consistent with theoretical models of disks (e.g. Kim et al. (2011) if we assume that the thermal pressure in HII regions is comparable to the total diffuse gas pressure at the midplane of the diffuse neutral gas. It is also in agreement with the results from star-forming galaxies at z ~ 2.5. We might infer that the starburst galaxies at low-redshift (z < 0.3) share similar physical properties to the galaxies at high redshift (z ~ 2.5).

  16. High-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry and gas chromatography-flame ionization detection characterization of Delta5-polyenoic fatty acids in triacylglycerols from conifer seed oils.

    PubMed

    Lísa, Miroslav; Holcapek, Michal; Rezanka, Tomás; Kabátová, Nadezda

    2007-03-30

    Edible conifer seeds can serve as a source of triacylglycerols (TGs) with unusual Delta5 unsaturated polymethylene interrupted fatty acids (UPIFAs), such as cis-5,9-octadecadienoic (taxoleic), cis-5,9,12-octadecatrienoic (pinolenic), cis-5,11-eicosadienoic (keteleeronic) and cis-5,11,14-eicosatrienoic acids (sciadonic). Conifer seed oils from European Larch (Larix decidua), Norway Spruce (Picea abies) and European Silver Fir (Abies alba) have been analyzed by non-aqueous reversed-phase high-performance liquid chromatography (NARP-HPLC) with atmospheric pressure chemical ionisation (APCI)-MS detection. The influence of different positions of double bonds in Delta5-UPIFAs on the retention and fragmentation behavior is described and used for the successful identification of TGs in each oil. TGs containing Delta5-UPIFAs have a higher retention in comparison with common TGs found in plant oils with single methylene interrupted Delta6(9)-FAs and also significantly changed relative abundances of fragment ions in APCI mass spectra. Results obtained from HPLC/MS analyses are supported by validated GC/FID analyses of fatty acid methyl esters after the transesterification. The total content of Delta5-UPIFAs is about 32% for European Larch, 27% for Norway Spruce and 20% for European Silver Fir. In total, 20 FAs with acyl chain lengths from 16 to 24 carbon atoms and from 0 to 3 double bonds have been identified in 64 triacylglycerols from 3 conifer seed oils.

  17. Highly ionized atoms toward HD 93521

    NASA Technical Reports Server (NTRS)

    Spitzer, Lyman, Jr.; Fitzpatrick, Edward L.

    1992-01-01

    Results are reported from the HST High Resolution Spectrograph observations of absorption features of C IV and Si IV in the spectrum of the high-latitude O star HD 93521 (l = 183 deg; b = 62 deg). A comparison of Si IV and C IV profiles showed that the FWHM of both features is about 50 km/sec, in contrast to the 7 km/sec found for one of the several S II features. The line centers for C IV and Si IV are at v = -67 km/sec and -60 km/sec, respectively. As the interval velocity decreases from 90 to 50 km/sec, the Si IV/C IV ratio of the column density per unit velocity interval increases from about 0.2 to 0.4. The result is qualitatively consistent with a fountain model of Shapiro and Benjamin (1991) if the slower gas has cooled and recombined more than the faster gas.

  18. Imaging spectrophotometry of ionized gas in NGC 1068. I - Kinematics of the narrow-line region

    NASA Technical Reports Server (NTRS)

    Cecil, Gerald; Bland, Jonathan; Tully, R. Brent

    1990-01-01

    The kinematics of collisionally excited forbidden N II 6548, 6583 across the inner 1 arcmin diameter of the nearby Seyfert galaxy NGC 1068 is mapped using an imaging Fabry-Perot interferometer and low-noise CCD. The stack of monochromatic images, which spatially resolved the high-velocity gas, was analyzed for kinematic and photometric content. Profiles agree well with previous long-slit work, and their complete spatial coverage makes it possible to constrain the gas volume distribution. It is found that the narrow-line region is distributed in a thick center-darkened, line-emitting cylinder that envelopes the collimated radio jet. Three distinct kinematic subsystems, of which the cylinder is composed, are discussed in detail. Detailed behavior of the emission-line profiles, at the few points in the NE quadrant with simple kinematics, argues that the ionized gas develops a significant component of motion perpendicular to the jet axis.

  19. A gas chromatography/electron capture/negative chemical ionization high-resolution mass spectrometry method for analysis of endogenous and exogenous N7-(2-hydroxyethyl)guanine in rodents and its potential for human biological monitoring.

    PubMed

    Wu, K Y; Scheller, N; Ranasinghe, A; Yen, T Y; Sangaiah, R; Giese, R; Swenberg, J A

    1999-08-01

    A gas chromatography/electron capture/negative chemical ionization high-resolution mass spectrometry (GC/EC/NCI-HRMS) method was developed for quantitating N7-(2-hydroxyethyl)guanine (N7-HEG) with excellent sensitivity and specificity. [4,5,6,8-(13)C(4)]-N7-HEG was synthesized, characterized, and quantitated using HPLC/electrospray ionization mass spectrometry (HPLC/ESI-MS) so it could serve as an internal standard. After being converted to its corresponding xanthine and derivatized with pentafluorobenzyl (PFB) bromide twice, the PFB derivative of N7-HEG was characterized using GC/EC/NCI-HRMS carried out at full scan mode. The most abundant fragment was at m/z 555, with a molecular formula of C(21)H(9)N(4)O(3)F(10), resulting from the loss of one PFB group. By monitoring m/z 555.0515 (analyte) and m/z 559.0649 (internal standard), this assay demonstrated a linear relationship over a range of 1 fmol to 1 pmol of N7-HEG versus 20 fmol of [(13)C(4)]-N7-HEG on column. The limit of detection (LOD) for the complete assay was 600 amol (S/N = 5) injected on column. The variation of this assay was within 15% from 1 to 20 fmol of N7-HEG versus 2 fmol of [(13)C(4)]-N7-HEG with four replications for each calibration standard. Two hundred to three hundred micrograms of spleen DNA of control rats and mice and 100 microg of spleen DNA of rats and mice exposed to 3000 ppm ethylene for 6 h/day for 5 days were analyzed using GC/EC/NCI-HRMS. The amounts of N7-HEG varied from 0.2 to 0.3 pmol/micromol of guanine in tissues of control rats. Ethylene-exposed animals had 5-15-fold higher N7-HEG levels than controls. This assay was able to quantitate N7-HEG in 25-30 microg of DNA from human lymphocytes with excellent specificity. This was due in part to human tissues having 10-15-fold higher amounts of endogenous N7-HEG than rodents. These results show that this GC/EC/NCI-HRMS method is highly sensitive and specific and can be used in biological monitoring and molecular dosimetry and

  20. Spatially resolved integral field spectroscopy of the ionized gas in IZw18

    NASA Astrophysics Data System (ADS)

    Kehrig, C.; Vílchez, J. M.; Pérez-Montero, E.; Iglesias-Páramo, J.; Hernández-Fernández, J. D.; Duarte Puertas, S.; Brinchmann, J.; Durret, F.; Kunth, D.

    2016-07-01

    We present a detailed 2D study of the ionized ionized interstellar medium (ISM) of IZw18 using new Potsdam Multi-Aperture Spectrophotometer-integral field unit (PMAS-IFU) optical observations. IZw18 is a high-ionization galaxy which is among the most metal-poor starbursts in the local Universe. This makes IZw18 a local benchmark for understanding the properties most closely resembling those prevailing at distant starbursts. Our IFU aperture (˜1.4 × 1.4 kpc2) samples the entire IZw18 main body and an extended region of its ionized gas. Maps of relevant emission lines and emission line ratios show that higher-excitation gas is preferentially located close to the north-west knot and thereabouts. We detect a Wolf-Rayet feature near the north-west knot. We derive spatially resolved and integrated physical-chemical properties for the ionized gas in IZw18. We find no dependence between the metallicity indicator R23 and the ionization parameter (as traced by [O III]/[O II]) across IZw18. Over ˜0.30 kpc2, using the [O III] λ4363 line, we compute Te[O III] values (˜15 000-25 000 K), and oxygen abundances are derived from the direct determinations of Te[O III]. More than 70 per cent of the higher-Te[O III] (≳22 000 K) spaxels are He IIλ4686-emitting spaxels too. From a statistical analysis, we study the presence of variations in the ISM physical-chemical properties. A galaxy-wide homogeneity, across hundreds of parsecs, is seen in O/H. Based on spaxel-by-spaxel measurements, the error-weighted mean of 12 + log(O/H) = 7.11 ± 0.01 is taken as the representative O/H for IZw18. Aperture effects on the derivation of O/H are discussed. Using our IFU data we obtain, for the first time, the IZw18 integrated spectrum.

  1. Determination of equilibrium composition of thermally ionized monoatomic gas under different physical conditions

    NASA Astrophysics Data System (ADS)

    Romanova, M. S.; Rydalevskaya, M. A.

    2017-05-01

    Perfect gas mixtures that result from thermal ionization of spatially and chemically homogeneous monoatomic gases are considered. Equilibrium concentrations of the components of such mixtures are determined using integration over the momentum space and summation with respect to energy levels of the distribution functions that maximize the entropy of system under condition for constancy of the total number of nuclei and electrons. It is demonstrated that such a method allows significant simplification of the calculation of the equilibrium composition for ionized mixtures at different temperatures and makes it possible to study the degree of ionization of gas versus gas density and number in the periodic table of elements.

  2. Electron impact ionization of the gas-phase sorbitol

    NASA Astrophysics Data System (ADS)

    Chernyshova, Irina; Markush, Pavlo; Zavilopulo, Anatoly; Shpenik, Otto

    2015-03-01

    Ionization and dissociative ionization of the sorbitol molecule by electron impact have been studied using two different experimental methods. In the mass range of m/ z = 10-190, the mass spectra of sorbitol were recorded at the ionizing electron energies of 70 and 30 eV. The ion yield curves for the fragment ions have been analyzed and the appearance energies of these ions have been determined. The relative total ionization cross section of the sorbitol molecule was measured using monoenergetic electron beam. Possible fragmentation pathways for the sorbitol molecule were proposed.

  3. Alfvén ionization in an MHD-gas interactions code

    NASA Astrophysics Data System (ADS)

    Wilson, A. D.; Diver, D. A.

    2016-07-01

    A numerical model of partially ionized plasmas is developed in order to capture their evolving ionization fractions as a result of Alfvén ionization (AI). The mechanism of, and the parameter regime necessary for, AI is discussed and an expression for the AI rate based on fluid parameters, from a gas-MHD model, is derived. This AI term is added to an existing MHD-gas interactions' code, and the result is a linear, 2D, two-fluid model that includes momentum transfer between charged and neutral species as well as an ionization rate that depends on the velocity fields of both fluids. The dynamics of waves propagating through such a partially ionized plasma are investigated, and it is found that AI has a significant influence on the fluid dynamics as well as both the local and global ionization fraction.

  4. Alfvén ionization in an MHD-gas interactions code

    SciTech Connect

    Wilson, A. D.; Diver, D. A.

    2016-07-15

    A numerical model of partially ionized plasmas is developed in order to capture their evolving ionization fractions as a result of Alfvén ionization (AI). The mechanism of, and the parameter regime necessary for, AI is discussed and an expression for the AI rate based on fluid parameters, from a gas-MHD model, is derived. This AI term is added to an existing MHD-gas interactions' code, and the result is a linear, 2D, two-fluid model that includes momentum transfer between charged and neutral species as well as an ionization rate that depends on the velocity fields of both fluids. The dynamics of waves propagating through such a partially ionized plasma are investigated, and it is found that AI has a significant influence on the fluid dynamics as well as both the local and global ionization fraction.

  5. Ionized gas outflows and global kinematics of low-z luminous star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Arribas, S.; Colina, L.; Bellocchi, E.; Maiolino, R.; Villar-Martín, M.

    2014-08-01

    We study the kinematic properties of the ionised gas outflows and ambient interstellar medium (ISM) in a large and representative sample of local luminous and ultra-luminous infrared galaxies (U/LIRGs) (58 systems, 75 galaxies) at galactic and sub-galactic (i.e., star-forming clumps) scales, thanks to integral field spectroscopy (IFS)-based high signal-to-noise integrated spectra. The velocity dispersion of the ionized ISM in U/LIRGs (⟨ σ ⟩ ~ 70 km s-1) is larger than in lower luminosity local star-forming galaxies (⟨ σ ⟩ ~ 25 km s-1). While for isolated disc LIRGs star formation appears to sustain turbulence, gravitational energy release associated with interactions and mergers plays an important role in driving σ in the U/LIRG range. We find that σ has a dependency on the star formation rate density (ΣSFR), which is weaker than expected if it were driven by the energy released by the starburst. The relatively small role of star formation (SF) driving the σ in U/LIRGs is reinforced by the lack of an increase in σ associated with high luminosity SF clumps. We also find that the impact of an active galactic nucleus (AGN) in ULIRGs is strong, increasing on average σ by a factor 1.5. Low-z U/LIRGs cover a range of velocity dispersion (σ ~ 30 to 100 km s-1) and star formation rate density (ΣSFR ~ 0.1 to 20 M⊙ yr-1 kpc-2) similar to those of high-z SFGs. Moreover, the observed weak dependency of σ on ΣSFR for local U/LIRGs (σ ∝ ΣSFR+0.06) is in very good agreement with that measured in some high-z samples. The presence of ionized gas outflows in U/LIRGs seems universal based on the detection of a broad, usually blueshifted, Hα line. The observed dependency of the maximum velocity of the outflow (Vmax) on the star formation rate (SFR) is of the type Vmax(non - AGN) ∝ SFR(LIR)+ 0.24. We find that AGNs in U/LIRGs are able to generate faster (~×2) and more massive (~× 1.4) ionized gas outflows than pure starbursts. The derived ionized mass

  6. Miniature triaxial metastable ionization detector for gas chromatographic trace analysis of extraterrestrial volatiles.

    PubMed

    Woeller, F H; Kojiro, D R; Carle, G C

    1984-04-01

    Gas chromatography has found highly successful application in NASA's flight programs. Gas chromatographs have been flown to both Mars and Venus where detailed compositional measurements were made. These instruments were quite small and relatively sensitive when compared to commercially available instruments; however, they do not appear adequate for future missions currently being planned. The earlier flight GC's had incorporated thermistor bead thermal conductivity cells as the detector. This detector requires very precise temperature control and only provides about 1 ppm sensitivity. Temperature stabilization causes the detector to be quite heavy, i.e., about 200 g. Greater sensitivity will be required for measurements of trace components in extraterrestrial environments. Review of other detector types revealed the metastable ionization detector as a likely candidate because of its superior thermal stability and high sensitivity. The metastable detector, first described by Lovelock as an argon ionization detector, has been studied and somewhat modified by others. The commercial design by Hartmann and Dimick was used for comparison purposes in our work. In the past, three features of the metastable detector are prominent: it has part-per-billion sensitivity, contamination must be carefully controlled, and anomalous response is common. Since it is an ionization detector, however, temperature instabilities do not cause the major perturbations experienced by the thermal conductivity detectors. This paper describes a miniature metastable ionization detector featuring an unconventional electrode configuration, whose performance characteristics parallel those of traditional design, while its weight is quite small. The prototype has been used in our laboratories routinely for 2 years, and the concept will be incorporated into a flight GC for use in the Space Shuttle.

  7. Ionizing potential waves and high-voltage breakdown streamers.

    NASA Technical Reports Server (NTRS)

    Albright, N. W.; Tidman, D. A.

    1972-01-01

    The structure of ionizing potential waves driven by a strong electric field in a dense gas is discussed. Negative breakdown waves are found to propagate with a velocity proportional to the electric field normal to the wavefront. This causes a curved ionizing potential wavefront to focus down into a filamentary structure, and may provide the reason why breakdown in dense gases propagates in the form of a narrow leader streamer instead of a broad wavefront.

  8. A reservoir of ionized gas in the galactic halo to sustain star formation in the Milky Way.

    PubMed

    Lehner, Nicolas; Howk, J Christopher

    2011-11-18

    Without a source of new gas, our Galaxy would exhaust its supply of gas through the formation of stars. Ionized gas clouds observed at high velocity may be a reservoir of such gas, but their distances are key for placing them in the galactic halo and unraveling their role. We have used the Hubble Space Telescope to blindly search for ionized high-velocity clouds (iHVCs) in the foreground of galactic stars. We show that iHVCs with 90 ≤ |v(LSR)| ≲ 170 kilometers per second (where v(LSR) is the velocity in the local standard of rest frame) are within one galactic radius of the Sun and have enough mass to maintain star formation, whereas iHVCs with |v(LSR)| ≳ 170 kilometers per second are at larger distances. These may be the next wave of infalling material.

  9. Astronomical redshifts of highly ionized regions

    NASA Astrophysics Data System (ADS)

    Hansen, Peter M.

    2014-07-01

    Astronomical or cosmological redshifts are an observable property of extragalactic objects and have historically been wholly attributed to the recessional velocity of that object. The question of other, or intrinsic, components of the redshift has been highly controversial since it was first proposed. This paper investigates one theoretical source of intrinsic redshift that has been identified. The highly ionized regions of Active Galactic Nuclei (AGN) and Quasi-Stellar Objects (QSO) are, by definition, plasmas. All plasmas have electromagnetic scattering characteristics that could contribute to the observed redshift. To investigate this possibility, one region of a generalized AGN was selected, the so called Broad Line Region (BLR). Even though unresolvable with current instrumentation, physical estimates of this region have been published for years in the astronomical literature. These data, selected and then averaged, are used to construct an overall model that is consistent with the published data to within an order of magnitude. The model is then subjected to a theoretical scattering investigation. The results suggest that intrinsic redshifts, derivable from the characteristics of the ambient plasma, may indeed contribute to the overall observed redshift of these objects.

  10. A Three Dimensional Beam Profile Monitor Based on Residual Gas Ionization

    SciTech Connect

    Lewis, T.A.; Shapira, D.

    1998-11-04

    A three-dimensional beam profile monitor based on tracking the ionization of the residual gas molecules in the evacuated beam pipe is described. Tracking in position and time of the ions and electrons produced in the ionization enables simultaneous position sampling in three dimensions. Special features which make it possible to sample very low beam currents were employed.

  11. Evaluation of Gas-filled Ionization Chamber Method for Radon Measurement at Two Reference Facilities

    SciTech Connect

    Ishikawa, Tetsuo; Tokonami, Shinji; Kobayashi, Yosuke; Sorimachi, Atsuyuki; Yatabe, Yoshinori; Miyahara, Nobuyuki

    2008-08-07

    For quality assurance, gas-filled ionization chamber method was tested at two reference facilities for radon calibration: EML (USA) and PTB (Germany). Consequently, the radon concentrations estimated by the ionization chamber method were in good agreement with the reference radon concentrations provided by EML as well as PTB.

  12. Infrared spectroscopy of ionized corannulene in the gas phase

    NASA Astrophysics Data System (ADS)

    Galué, Héctor Alvaro; Rice, Corey A.; Steill, Jeffrey D.; Oomens, Jos

    2011-02-01

    The gas-phase infrared spectra of radical cationic and protonated corannulene were recorded by infrared multiple-photon dissociation (IRMPD) spectroscopy using the IR free electron laser for infrared experiments. Electrospray ionization was used to generate protonated corannulene and an IRMPD spectrum was recorded in a Fourier-transform ion cyclotron resonance mass spectrometer monitoring H-loss as a function of IR frequency. The radical cation was produced by 193-nm UV photoionization of the vapor of corannulene in a 3D quadrupole trap and IR irradiation produces H, H2, and C2Hx losses. Summing the spectral response of the three fragmentation channels yields the IRMPD spectrum of the radical cation. The spectra were analyzed with the aid of quantum-chemical calculations carried out at various levels of theory. The good agreement of theoretical and experimental spectra for protonated corannulene indicates that protonation occurs on one of the peripheral C-atoms, forming an sp3 hybridized carbon. The spectrum of the radical cation was examined taking into account distortions of the C5v geometry induced by the Jahn-Teller effect as a consequence of the degenerate 2E1 ground electronic state. As indicated by the calculations, the five equivalent Cs minima are separated by marginal barriers, giving rise to a dynamically distorted system. Although in general the character of the various computed vibrational bands appears to be in order, only a qualitative match to the experimental spectrum is found. Along with a general redshift of the calculated frequencies, the IR intensities of modes in the 1000-1250 cm-1 region show the largest discrepancy with the harmonic predictions. In addition to CH "in-plane" bending vibrations, these modes also exhibit substantial deformation of the pentagonal inner ring, which may relate directly to the vibronic interaction in the radical cation.

  13. Collisions of fast multicharged ions in gas targets: Charge transfer and ionization

    NASA Astrophysics Data System (ADS)

    Schlachter, A. S.

    1981-05-01

    Measurements of cross sections for charge transfer and ionization of H2 and rare-gas targets were made with fast, highly stripped projectiles in charge states as high as 59+. An empirical scaling rule for electron-capture cross section in H2 valid at energies above 275 keV/amu was found. Similar scaling might exist for other target gases. Cross sections are generally in good agreement with theory. A scaling rule was found for electron loss from H in collisions with a fast highly stripped projectile, based on Olson's classical-trajectory Monte-Carlo calculations, and confirmed by measurements in an H2 target. A similar scaling rule was for net ionization of rare-gas targets, based on Olson's CTMC calculations and the independent-electron model. Measurements are essentially consistent with the scaled cross sections. Calculations and measurements of recoil-ion charge-state spectra show large cross sections for the production of highly charged slow recoil ions.

  14. Determination of benzene, toluene, ethylbenzene and xylenes in indoor air at environmental levels using diffusive samplers in combination with headspace solid-phase microextraction and high-resolution gas chromatography-flame ionization detection.

    PubMed

    Elke, K; Jermann, E; Begerow, J; Dunemann, L

    1998-11-27

    An improved analytical method for passive air sampling is presented based on a combination of commercially available diffusive samplers with headspace solid-phase microextraction and high-resolution gas chromatography with flame ionization detection (HRGC-FID). This procedure is targeted for short-term BTEX (benzene, toluene, ethylbenzene and o-, m- and p-xylenes) determinations at environmental concentrations and can be applied for sampling intervals between 30 min and 24 h. The analytes are adsorbed onto the charcoal pad of a passive sampler and then extracted with carbon disulphide-methanol. After removal of the carbon disulphide by xanthation, the BTEXs are enriched on a Carboxen SPME fiber, thermally desorbed and analysed by HRGC-FID. Detection limits for a sampling interval of 2 h are between 0.4 and 2 micrograms/m3, within-series precision ranges between 6.6 and 12.8%, day-to-day precision is between 11.1 and 15.2%. The results obtained with this procedure are validated by comparison with active sampling. Detection limits and a further reduction of the sampling time are limited by blanks of the chemicals and the diffusive samplers. Procedures to eliminate these blanks are described in detail. Applications such as the determination of BTEXs in indoor air inside buildings, inside a train and a car are presented, indicating the usefulness of the described procedure for short-term measurements of environmental BTEX concentrations. An advantage of passive samplers is the storage stability for at least six months, which is essential for its use in large epidemiological studies.

  15. Gas chromatography/chemical ionization triple quadrupole mass spectrometry analysis of anabolic steroids: ionization and collision-induced dissociation behavior.

    PubMed

    Polet, Michael; Van Gansbeke, Wim; Van Eenoo, Peter; Deventer, Koen

    2016-02-28

    The detection of new anabolic steroid metabolites and new designer steroids is a challenging task in doping analysis. Switching from electron ionization gas chromatography triple quadrupole mass spectrometry (GC/EI-MS/MS) to chemical ionization (CI) has proven to be an efficient way to increase the sensitivity of GC/MS/MS analyses and facilitate the detection of anabolic steroids. CI also extends the possibilities of GC/MS/MS analyses as the molecular ion is retained in its protonated form due to the softer ionization. In EI it can be difficult to find previously unknown but expected metabolites due to the low abundance or absence of the molecular ion and the extensive (and to a large extent unpredictable) fragmentation. The main aim of this work was to study the CI and collision-induced dissociation (CID) behavior of a large number of anabolic androgenic steroids (AAS) as their trimethylsilyl derivatives in order to determine correlations between structures and CID fragmentation. Clarification of these correlations is needed for the elucidation of structures of unknown steroids and new metabolites. The ionization and CID behavior of 65 AAS have been studied using GC/CI-MS/MS with ammonia as the reagent gas. Glucuronidated AAS reference standards were first hydrolyzed to obtain their free forms. Afterwards, all the standards were derivatized to their trimethylsilyl forms. Full scan and product ion scan analyses were used to examine the ionization and CID behavior. Full scan and product ion scan analyses revealed clear correlations between AAS structure and the obtained mass spectra. These correlations were confirmed by analysis of multiple hydroxylated, methylated, chlorinated and deuterated analogs. AAS have been divided into three groups according to their ionization behavior and into seven groups according to their CID behavior. Correlations between fragmentation and structure were revealed and fragmentation pathways were postulated. Copyright © 2016 John Wiley

  16. Miniaturized ionization gas sensors from single metal oxide nanowires.

    PubMed

    Hernandez-Ramirez, Francisco; Prades, Juan Daniel; Hackner, Angelika; Fischer, Thomas; Mueller, Gerhard; Mathur, Sanjay; Morante, Joan Ramon

    2011-02-01

    Gas detection experiments were performed with individual tin dioxide (SnO2) nanowires specifically configured to observe surface ion (SI) emission response towards representative analyte species. These devices were found to work at much lower temperatures (T≈280 °C) and bias voltages (V≈2 V) than their micro-counterparts, thereby demonstrating the inherent potential of individual nanostructures in building functional nanodevices. High selectivity of our miniaturized sensors emerges from the dissimilar sensing mechanisms of those typical of standard resistive-type sensors (RES). Therefore, by employing this detection principle (SI) together with RES measurements, better selectivity than that observed in standard metal oxide sensors could be demonstrated. Simplicity and specificity of the gas detection as well as low-power consumption make these single nanowire devices promising technological alternatives to overcome the major drawbacks of solid-state sensor technologies.

  17. CAN THE LYMAN CONTINUUM LEAKED OUT OF H II REGIONS EXPLAIN DIFFUSE IONIZED GAS?

    SciTech Connect

    Seon, Kwang-Il

    2009-09-20

    We present an attempt to explain the diffuse Halpha emission of a face-on galaxy M 51 with the 'standard' photoionization model, in which the Lyman continuum (Lyc) escaping from H II regions propagates large distances into the diffuse interstellar medium (ISM). The diffuse Halpha emission of M 51 is analyzed using thin slab models and exponential disk models in the context of the 'on-the-spot' approximation. The scale height of the ionized gas needed to explain the diffuse Halpha emission with the scenario is found to be of the order of {approx}1-2 kpc, consistent with those of our Galaxy and edge-on galaxies. The model also provides a vertical profile, when the galaxy is viewed edge-on, consisting of two-exponential components. However, it is found that an incredibly low absorption coefficient of kappa{sub 0} {approx} 0.4-0.8 kpc{sup -1} at the galactic plane, or, equivalently, an effective cross section as low as sigma{sub eff} {approx} 10{sup -5} of the photoionization cross section at 912 A is required to allow the stellar Lyc photons to travel through the H I disk. Such a low absorption coefficient is out of accord with the properties of the ISM. Furthermore, we found that even the model that has the diffuse ionized gas (DIG) phase only and no H I gas phase shows highly concentrated Halpha emissions around H II regions, and can account for only {approx}<26% of the Halpha luminosity of the DIG. This result places a strong constraint on the ionizing source of the DIG. We also report that the Halpha intensity distribution functions not only of the DIG, but also of H II regions in M 51, appear to be lognormal.

  18. Jet-driven outflows of ionized gas in the nearby radio galaxy 3C 293

    NASA Astrophysics Data System (ADS)

    Mahony, E. K.; Oonk, J. B. R.; Morganti, R.; Tadhunter, C.; Bessiere, P.; Short, P.; Emonts, B. H. C.; Oosterloo, T. A.

    2016-01-01

    Fast outflows of gas, driven by the interaction between the radio jets and interstellar medium (ISM) of the host galaxy, are being observed in an increasing number of galaxies. One such example is the nearby radio galaxy 3C 293. In this paper we present integral field unit observations taken with OASIS on the William Herschel Telescope, enabling us to map the spatial extent of the ionized gas outflows across the central regions of the galaxy. The jet-driven outflow in 3C 293 is detected along the inner radio lobes with a mass outflow rate ranging from ˜0.05 to 0.17 M⊙ yr-1 (in ionized gas) and corresponding kinetic power of ˜0.5-3.5 × 1040 erg s-1. Investigating the kinematics of the gas surrounding the radio jets (i.e. not directly associated with the outflow), we find linewidths broader than 300 km s-1 up to 5 kpc in the radial direction from the nucleus (corresponding to 3.5 kpc in the direction perpendicular to the radio axis at maximum extent). Along the axis of the radio jet linewidths >400 km s-1 are detected out to 7 kpc from the nucleus and linewidths of >500 km s-1 at a distance of 12 kpc from the nucleus, indicating that the disturbed kinematics clearly extend well beyond the high surface brightness radio structures of the jets. This is suggestive of the cocoon structure seen in simulations of jet-ISM interaction and implies that the radio jets are capable of disturbing the gas throughout the central regions of the host galaxy in all directions.

  19. Positron Impact Ionization in Noble Gas Atoms and Diatomic Molecules

    NASA Astrophysics Data System (ADS)

    Marler, J. P.

    2005-05-01

    Results are presented for absolute positronium formation and direct ionization by positron impact on Ne, Ar, Kr, Xe, N2, CO and O2 at energies from threshold up to 90 eV. The experiments use a high-resolution, trap-based positron beam and exploit the properties of positron orbits in a magnetic field [1]. Results for the noble gases are compared with theoretical predictions and with measurements obtained using a significantly different method [2]. Results for diatomic molecules are compared to other available measurements and theoretical calculations where available. There is generally good agreement between the experimental measurements, providing an important benchmark for theoretical calculations. Intriguing features in Ar and O2 will be discussed. [1] J.P. Sullivan, S.J. Gilbert, J.P. Marler, R.G. Greaves, S.J. Buckman and C.M. Surko., Phys. Rev. A. 66, 042708 (2002) [2] J.P. Marler, J.P. Sullivan and C.M. Surko, Phys. Rev. A (2005), in press.

  20. High efficiency ionizer using a hollow cathode discharge plasma

    SciTech Connect

    Alessi, J.G.; Prelec, K.

    1984-01-01

    A proposal for an ionizer using a hollow cathode discharge plasma is described. Ionization is via the very high current density electron beam component in the plasma, as well as from charge exchange with plasma ions. Extraction of a He/sup +/ current corresponding to approximately 50% of the incoming atomic beam flux should be possible.

  1. LTC1877 High Efficiency Regulator Total Ionizing Dose Test Report

    NASA Technical Reports Server (NTRS)

    Oldham, Timothy; Pellish, Jonathan; Boutte, Alvin

    2012-01-01

    This report presents total ionizing dose evaluation data for the Linear Technology Corporation LTC1877 high efficiency monolithic synchronous step-down regulator. Data sheet parameters were tracked as a function of ionizing dose up to a total of 20 krad(SiO2). Control devices were also used.

  2. Observations of extended and counterrotating disks of ionized gas in S0 galaxies

    NASA Technical Reports Server (NTRS)

    Dettmar, Ralf-Juergen; Jullien-Dettmar, Marlies; Barteldrees, Andreas

    1990-01-01

    While many E/S0 galaxies have been found to show emission line spectra in their nuclear regions, the question of the presence and nature of extended disks of ionized gas in these galaxies has been addressed only in recent years. Typically the ionized gas is detected in the inner region on a scale of approx. 1 kpc (e.g., Phillips et al. 1986, Caldwell 1984). Here researchers present evidence that the disks of ionized gas of at least some S0 galaxies are much more extended than previously believed. In addition, with the detection of the counterrotation of gas and stars in NGC 7007 they strengthen the basis for arguments that the source of gas in S0 galaxies is external

  3. Cosmic ray studies with a gas Cherenkov counter in association with an ionization spectrometer

    NASA Technical Reports Server (NTRS)

    Balasubrahmanyan, V. K.; Ormes, J. F.; Arens, J. F.; Siohan, F.; Yodh, G. B.; Simon, M.; Spiegelhauer, H.

    1980-01-01

    The results from a balloon-borne gas Cherenkov counter (threshold 16.5 GeV/nucleon) and an ionization spectrometer are presented. The gas Cherenkov counter provides an absolute energy distribution for the response of the calorimeter for 5 or = Z 26 nuclei of cosmic rays. The contribution of scintillation to the gas Cherenkov pulse height was obtained by independently selecting particles below the gas Cherenkov threshold using the ionization spectrometer. Energy spectra were derived by minimizing the chi squared between Monte Carlo simulted data and flight data. Best fit power laws, dN/dE = AE-gamma, were determined for C, N, O, Ne, Mg, and Si. The power laws, all consistent with E (-2.7) are not good fits to the data. A better fit is obtained using the spectrum derived from the spectrometer. The data from the ionization calorimeter and the gas Cherenkov are thus completely self-consistent.

  4. Characteristics of krypton ion emission from a gas field ionization source with a single atom tip

    NASA Astrophysics Data System (ADS)

    Shichi, Hiroyasu; Matsubara, Shinichi; Hashizume, Tomihiro

    2017-06-01

    A scanning ion beam instrument equipped with a gas field ionization source (GFIS) has been commercialized, but only helium and neon are currently available as GFISs. The characteristics of krypton ion emission from a single atom tip (SAT) have not been reported yet. In this study, the characteristics of krypton ion emission were investigated by field ion microscopy. At 65 K, the krypton ion emission current reached approximately 40 pA, which is 1 order of magnitude higher than that at 130 K. As the krypton gas pressure was increased, the krypton ion current increased. At a pressure of 0.3 Pa, the emission current was anticipated to reach 200 pA, which may be high enough for nanofabrication. The variation of the krypton ion current was as low as 5% in one hour. We concluded that a krypton ion beam instrument equipped with a GFIS will be a powerful tool for nanofabrication.

  5. A sensitive gas chromatography detector based on atmospheric pressure chemical ionization by a dielectric barrier discharge.

    PubMed

    Kirk, Ansgar T; Last, Torben; Zimmermann, Stefan

    2017-02-03

    In this work, we present a novel concept for a gas chromatography detector utilizing an atmospheric pressure chemical ionization which is initialized by a dielectric barrier discharge. In general, such a detector can be simple and low-cost, while achieving extremely good limits of detection. However, it is non-selective apart from the use of chemical dopants. Here, a demonstrator manufactured entirely from fused silica capillaries and printed circuit boards is shown. It has a size of 75×60×25mm(3) and utilizes only 2W of power in total. Unlike other known discharge detectors, which require high-purity helium, this detector can theoretically be operated using any gas able to form stable ion species. Here, purified air is used. With this setup, limits of detection in the low parts-per-billion range have been obtained for acetone.

  6. Shock Structure Analysis and Aerodynamics in a Weakly Ionized Gas Flow

    NASA Technical Reports Server (NTRS)

    Saeks, R.; Popovic, S.; Chow, A. S.

    2006-01-01

    The structure of a shock wave propagating through a weakly ionized gas is analyzed using an electrofluid dynamics model composed of classical conservation laws and Gauss Law. A viscosity model is included to correctly model the spatial scale of the shock structure, and quasi-neutrality is not assumed. A detailed analysis of the structure of a shock wave propagating in a weakly ionized gas is presented, together with a discussion of the physics underlying the key features of the shock structure. A model for the flow behind a shock wave propagating through a weakly ionized gas is developed and used to analyze the effect of the ionization on the aerodynamics and performance of a two-dimensional hypersonic lifting body.

  7. Femtosecond interferometry of propagation of a laminar ionization front in a gas

    SciTech Connect

    Gizzi, L. A.; Giulietti, A.; Giulietti, D.; Labate, L.; Tomassini, P.; Galimberti, M.; Koester, P.; Martin, Ph.; Ceccotti, T.; De Oliveira, P.; Monot, P.

    2006-09-15

    We use optical interferometry to investigate ultrafast ionization induced by an intense, ultrashort laser pulse propagating in a helium gas. Besides standard phase shift information, our interferograms show a localized region of fringe visibility depletion (FVD) that moves along the laser propagation axis at luminal velocity. We find that such a loss of visibility can be quantitatively explained by the ultrafast change of refractive index due to the field ionization of the gas in the laser pulse width. We demonstrate that by combining the post facto phase shift distribution with the probe pulse transit effect in the ionizing region, the analysis of the observed FVD yields significant information on the ultrafast dynamics of propagation of the ionization front in the gas.

  8. Atmospheric Pressure Ionization Using a High Voltage Target Compared to Electrospray Ionization

    NASA Astrophysics Data System (ADS)

    Lubin, Arnaud; Bajic, Steve; Cabooter, Deirdre; Augustijns, Patrick; Cuyckens, Filip

    2017-02-01

    A new atmospheric pressure ionization (API) source, viz. UniSpray, was evaluated for mass spectrometry (MS) analysis of pharmaceutical compounds by head-to-head comparison with electrospray ionization (ESI) on the same high-resolution MS system. The atmospheric pressure ionization source is composed of a grounded nebulizer spraying onto a high voltage, cylindrical stainless steel target. Molecules are ionized in a similar fashion to electrospray ionization, predominantly producing protonated or deprotonated species. Adduct formation (e.g., proton and sodium adducts) and in-source fragmentation is shown to be almost identical between the two sources. The performance of the new API source was compared with electrospray by infusion of a mix of 22 pharmaceutical compounds with a wide variety of functional groups and physico-chemical properties (molecular weight, logP, and pKa) in more than 100 different conditions (mobile phase strength, solvents, pH, and flow rate). The new API source shows an intensity gain of a factor 2.2 compared with ESI considering all conditions on all compounds tested. Finally, some hypotheses on the ionization mechanism, similarities, and differences with ESI, are discussed.

  9. Gas kinematics and ionization along the extended sight line to HD 116852

    NASA Technical Reports Server (NTRS)

    Sembach, Kenneth R.; Savage, Blair D.

    1994-01-01

    We present Goddard High-Resolution Spectrograph intermediate observations of the interstellar medium toward HD 116852, a low halo star at a distance of 4.8 kpc (z = -1.3 kpc) in the direction l = 304. deg 9, b = 16.deg 1. The small science aperture observations have signal-to-noise ratios ranging from 30 to 90 and resolutions of 11 to 18 km/s (FWHM). We confirm the optical MK classification of this star through an analysis of its ultraviolet photosperic and stellar wind profiles. We detect interstellar lines of Al III, Si IV, C IV, and N V together with lines of C I, C I*, C I**, Si II, Ge II, P II, and Ni II. We convert the Mg II, P II, S II, Al III, Si IV, C IV, and N V profiles into measure of apparent column density as a function of LSR velocity. Gas scale height, velocity dispersion, and differential Galactic rotation effects govern the profile shapes. A simple computer model of the expected sight line column density profiles for the low and high ion species indicates that the gas velocity dispersions and scale heights increase as the ionization level of the gas increases. We find scale heigts H greater than or = 1 kpc for the high ions, which are comparable to the z-distance of the star, whereas we find H approximatley = 0.6 to 0.7 kpc for A1 III and H approximatley 0.1 kpc for P II and Ge II. An enhancement in the Al II profile near -15 km/s accounts for approximately 25% of the A1 III column along the sight line and probably arises within gas located approximately 500 pc below the Sagittarius-Carina spiral arm link. Portions of the broad underlying A1 III distribution are associated with the higher ionization lines, perhaps in conductive interfaces. The presence of N V and the column density ratios of Si IV, C IV, and N V favor the interpretation that much of the high ion absorption is produced by collisional ionization in gas with T = 1-3 x 10(exp 5) K. An enhancement near -35 km/s in both the Si IV and C IV profiles may be due to an outflow from the Norma

  10. Gas kinematics and ionization along the extended sight line to HD 116852

    NASA Technical Reports Server (NTRS)

    Sembach, Kenneth R.; Savage, Blair D.

    1994-01-01

    We present Goddard High-Resolution Spectrograph intermediate observations of the interstellar medium toward HD 116852, a low halo star at a distance of 4.8 kpc (z = -1.3 kpc) in the direction l = 304. deg 9, b = 16.deg 1. The small science aperture observations have signal-to-noise ratios ranging from 30 to 90 and resolutions of 11 to 18 km/s (FWHM). We confirm the optical MK classification of this star through an analysis of its ultraviolet photosperic and stellar wind profiles. We detect interstellar lines of Al III, Si IV, C IV, and N V together with lines of C I, C I*, C I**, Si II, Ge II, P II, and Ni II. We convert the Mg II, P II, S II, Al III, Si IV, C IV, and N V profiles into measure of apparent column density as a function of LSR velocity. Gas scale height, velocity dispersion, and differential Galactic rotation effects govern the profile shapes. A simple computer model of the expected sight line column density profiles for the low and high ion species indicates that the gas velocity dispersions and scale heights increase as the ionization level of the gas increases. We find scale heigts H greater than or = 1 kpc for the high ions, which are comparable to the z-distance of the star, whereas we find H approximatley = 0.6 to 0.7 kpc for A1 III and H approximatley 0.1 kpc for P II and Ge II. An enhancement in the Al II profile near -15 km/s accounts for approximately 25% of the A1 III column along the sight line and probably arises within gas located approximately 500 pc below the Sagittarius-Carina spiral arm link. Portions of the broad underlying A1 III distribution are associated with the higher ionization lines, perhaps in conductive interfaces. The presence of N V and the column density ratios of Si IV, C IV, and N V favor the interpretation that much of the high ion absorption is produced by collisional ionization in gas with T = 1-3 x 10(exp 5) K. An enhancement near -35 km/s in both the Si IV and C IV profiles may be due to an outflow from the Norma

  11. STS-39 Critical Ionization Velocity (CIV) gas release from OV-103 payload bay

    NASA Image and Video Library

    1991-05-06

    STS039-367-006 (1 May 1991) --- One of the four compressed gas canisters on the forward port side of Discovery's cargo bay releases gas on flight day 4 of the STS-39 mission. The canisters are part of STS-39's Critical Ionization Velocity (CIV) experiment.

  12. Gauging Metallicity of Diffuse Gas under an Uncertain Ionizing Radiation Field

    NASA Astrophysics Data System (ADS)

    Chen, Hsiao-Wen; Johnson, Sean D.; Zahedy, Fakhri S.; Rauch, Michael; Mulchaey, John S.

    2017-06-01

    Gas metallicity is a key quantity used to determine the physical conditions of gaseous clouds in a wide range of astronomical environments, including interstellar and intergalactic space. In particular, considerable effort in circumgalactic medium (CGM) studies focuses on metallicity measurements because gas metallicity serves as a critical discriminator for whether the observed heavy ions in the CGM originate in chemically enriched outflows or in more chemically pristine gas accreted from the intergalactic medium. However, because the gas is ionized, a necessary first step in determining CGM metallicity is to constrain the ionization state of the gas which, in addition to gas density, depends on the ultraviolet background radiation field (UVB). While it is generally acknowledged that both the intensity and spectral slope of the UVB are uncertain, the impact of an uncertain spectral slope has not been properly addressed in the literature. This Letter shows that adopting a different spectral slope can result in an order of magnitude difference in the inferred CGM metallicity. Specifically, a harder UVB spectrum leads to a higher estimated gas metallicity for a given set of observed ionic column densities. Therefore, such systematic uncertainties must be folded into the error budget for metallicity estimates of ionized gas. An initial study shows that empirical diagnostics are available for discriminating between hard and soft ionizing spectra. Applying these diagnostics helps reduce the systematic uncertainties in CGM metallicity estimates.

  13. The kinematics of Milky Way halo gas. I - Observations of low-ionization species

    NASA Technical Reports Server (NTRS)

    Danly, Laura

    1989-01-01

    Ultraviolet interstellar line day observed with the IUE toward 70 halo stars and four extragalactic sight lines are analyzed in a study of the large-scale kinematic properties of the Milky Way halo gas. The motions of the low-ionization gas is focused on. Large systematic velocities are found, and a pronounced asymmetry in the absorption characteristics of halo gas toward the Galactic poles is indicated. In the north, substantial amounts of material are falling toward the disk at velocities up to about 120 km/s in the most extreme case. Toward the south, low-ionization material shows no extreme or systematic motions.

  14. The kinematics of Milky Way halo gas. I - Observations of low-ionization species

    NASA Technical Reports Server (NTRS)

    Danly, Laura

    1989-01-01

    Ultraviolet interstellar line day observed with the IUE toward 70 halo stars and four extragalactic sight lines are analyzed in a study of the large-scale kinematic properties of the Milky Way halo gas. The motions of the low-ionization gas is focused on. Large systematic velocities are found, and a pronounced asymmetry in the absorption characteristics of halo gas toward the Galactic poles is indicated. In the north, substantial amounts of material are falling toward the disk at velocities up to about 120 km/s in the most extreme case. Toward the south, low-ionization material shows no extreme or systematic motions.

  15. Detection of trace levels of triclopyr using capillary gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry.

    PubMed

    Begley, P; Foulger, B E

    1988-04-01

    Triclopyr, after esterification, is shown to be a suitable candidate for detection by gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry forming a characteristic carboxylate anion which offers a high detection sensitivity. A detection limit of 70 fg reaching the ionizer is indicated. Low backgrounds and an absence of chemical interferences are shown for vegetation extracts, using a simple method of extraction and derivatisation. A similar behaviour is demonstrated for 2,4-D and 2,4,5-T.

  16. The detection of dissolved gases in transformer oil by gas chromatography with helium ionization detector

    NASA Astrophysics Data System (ADS)

    Deng, Xian-qin; Fang, Hua; Li, Min-xian

    2017-07-01

    The GC-PDD with the technology of valve cutting and helium ionization detector was used to analyze the dissolved gases in ultra-high voltage(UHV) and extra-high voltage(EHV) transformer oil. The detection limit(DL) reached ppb grade, especially for the featuring gas—C2H2 and H2, whose DL could reach 5ppb and 11ppb respectively. The test reproducibility of the instrument was about 1% and the correlation coefficient of standard curve-r is greater or equal to 0.99, which showed obvious advantage compared with normal GC. In addition, the auxiliary gas of H2 was not used in this instrument, which completely improved the safety performance. Thus, the application of GC-PDD has significant meaning in warning potential malfunction inside the ultra-high voltage transformer in advance.

  17. Investigating the Diffuse Ionized Gas in the Magellanic Stream with Mapped WHAM Observations

    NASA Astrophysics Data System (ADS)

    Smart, Brianna; Haffner, L. Matthew; Barger, Kathleen; Hernandez, Mike

    2016-01-01

    We present early stages of an Hα survey of the Magellanic Stream using the Wisconsin H-Alpha Mapper (WHAM). While the neutral component of the Stream may extend 200° across the sky (Nidever et al. 2010), its ionized gas has not yet been studied in detail. Fox et al. 2014 find that the tidal debris in the Magellanic System contains twice as much ionized gas as neutral and may extend 30° away from the H I emission. However, such absorption-line studies are not sensitive to the overall morphology of the ionized gas. Using targeted Hα emission observations of the Magellanic Stream, Barger et al. 2015 find that although the warm ionized gas tracks the neutral gas, it often spans a few degrees away from the H I emission at slightly offset velocities. Using WHAM's unprecedented sensitivity to diffuse emission (~ 10s of mR) and its velocity resolution (12 km/s) to isolate Stream emission, we are now conducting the first full Hα survey of its ionized component. Here we present early results, including spatial and kinematic comparisons to the well-established neutral profile of the Stream. WHAM research and operations are supported through NSF Award AST-1108911.

  18. Prediction of Shock Wave Structure in Weakly Ionized Gas Flow by Solving MGD Equation

    NASA Technical Reports Server (NTRS)

    Deng, Z. T.; Oviedo-Rojas, Ruben; Chow, Alan; Litchford, Ron J.; Cook, Stephen (Technical Monitor)

    2002-01-01

    This paper reports the recent research results of shockwave structure predictions using a new developed code. The modified Rankine-Hugoniot relations across a standing normal shock wave are discussed and adopted to obtain jump conditions. Coupling a electrostatic body force to the Burnett equations, the weakly ionized flow field across the shock wave was solved. Results indicated that the Modified Rankine-Hugoniot equations for shock wave are valid for a wide range of ionization fraction. However, this model breaks down with small free stream Mach number and with large ionization fraction. The jump conditions also depend on the value of free stream pressure, temperature and density. The computed shock wave structure with ionization provides results, which indicated that shock wave strength may be reduced by existence of weakly ionized gas.

  19. Measurements of ultrafast laser-driven ionization and extreme gas nonlinearity

    NASA Astrophysics Data System (ADS)

    Zahedpour, Sina; Cheng, Yu-Hsiang; Wahlstrand, Jared; Milchberg, Howard

    2013-10-01

    A 2D spectral interferometry method for measuring high laser field phenomena such as laser-driven ionization and high field nonlinearity is introduced. The method is based on Single-shot Supercontinuum Spectral Interferometry, in which a chirped supercontinuum is used to probe the time-dependent refractive index induced by a pump pulse. A thin gas target ensures uniform intensity and minimizes refraction of the probe beam due to refractive index gradients. An imaging spectrometer allows measurement of the spatial dependence of the response along one direction. To measure in 2D, a motorized mirror scans the probe beam across the spectrometer slit. The technique has 3 micron spatial and 5 fs temporal resolution. The effective interaction length is measured interferometrically, allowing absolute calibration of the refractive index change. We present measurements of the absolute ionization rates of noble and molecular gases and their high field nonlinear response. Work supported by the Air Force Office of Scientific Research, the Office of Naval Research, the National Science Foundation, and the Dept. of Energy.

  20. Theoretical and Experimental Research of Capabilities of MHD Technology to Control Gas Flow with Non-Equilibrium Ionization

    DTIC Science & Technology

    2007-11-02

    experimental research of capabilities of using of MHD technology to control gas flow with non-equilibrium ionization. Cold gas flows will be considered, where...and MHD generator will be developed. Requirements to ionizer, MHD generator and flow parameters at which self- sustained operational mode of ionizer and...MHD generator is realized will be formulated. Possibilities of using of MHD control in gas-dynamical systems will be considered. Traditional use of

  1. Gas-phase chemiluminescence and chemi-ionization

    SciTech Connect

    Fontijn, A.

    1985-01-01

    The phenomena of chemiluminescence (or more broadly chemi-excitation) and chemi-ionization have major similarities from a fundamental kinetic and dynamic point of view. However, since the former has primarily been investigated using optical spectroscopic techniques and the latter largely by mass spectroscopic (and other gaseous electronic) methods, the two phenomena have apparently never, explicitly been discussed together in one volume. In addition to a number of review articles on each individual subject, several meetings and books have had chemiluminescence and bioluminescence as their theme and those have been dominated by condensed phase work. On the other hand, chemi-ionization is often discussed in the contest of gaseous electronics, plasma chemistry and combustion. It is the goal of this book to present a more unified understanding of the two phenomena.

  2. The Massive Stellar Population in the Diffuse Ionized Gas of M33

    NASA Technical Reports Server (NTRS)

    Hoopes, Charles G.; Walterbos, Rene A. M.

    1995-01-01

    We compare Far-UV, H alpha, and optical broadband images of the nearby spiral galaxy M33, to investigate the massive stars associated with the diffuse ionized gas. The H-alpha/FUV ratio is higher in HII regions than in the DIG, possibly indicating that an older population ionizes the DIG. The broad-band colors support this conclusion. The HII region population is consistent with a young burst, while the DIG colors resemble an older population with constant star formation. Our results indicate that there may be enough massive field stars to ionize the DIG, without the need for photon leakage from HII regions.

  3. The Contribution of Field OB Stars to the Ionization of the Diffuse Ionized Gas in M33

    NASA Astrophysics Data System (ADS)

    Hoopes, Charles G.; Walterbos, René A. M.

    2000-10-01

    We present a study of the ionizing stars associated with the diffuse ionized gas (DIG) and H II regions in the nearby spiral galaxy M33. We compare our Schmidt Hα image to the far-ultraviolet (FUV, 1520 Å) image from the Ultraviolet Imaging Telescope (UIT). The Hα/FUV ratio is higher in H II regions than in the DIG, suggesting an older population of ionizing stars in the DIG. Assuming ionization equilibrium, we convert the Hα flux to the number of Lyman continuum photons NLyc. When compared to models of evolving stellar populations, the NLyc/FUV ratio in H II regions is consistent with a young burst, while the DIG ratio resembles an older burst population, or a steady state population built up by constant star formation, which is probably a more accurate description of the stellar population in the field. The UIT data is complemented with archival FUV and optical images of a small portion of the disk of M33 obtained with WFPC2 on board the Hubble Space Telescope (HST). These images overlap low- and mid-luminosity H II regions as well as DIG, so we can investigate the stellar population in these environments. Using the HST FUV and optical photometry, we assign spectral types to the stars observed in DIG and H II regions. The photometry indicates that ionizing stars are present in the DIG. We compare the predicted ionizing flux with the amount required to produce the observed Hα emission, and we find that field OB stars in the HST images can account for 40%+/-12% of the ionization of the DIG, while the stars in H II regions can provide 107%+/-26% of the Hα luminosity of the H II regions. Due to the limited coverage of the HST data, we cannot determine if stars outside the HST fields ionize some of the DIG located in the HST fields, nor can we determine if photons from stars inside the HST fields leak out of the area covered by the HST fields. We do not find any correlation between leakage of ionizing photons and Hα luminosity for the H II regions in our HST

  4. HST/COS Observations of Ionized Gas Accretion at the Disk–Halo Interface of M33

    NASA Astrophysics Data System (ADS)

    Zheng, Y.; Peek, J. E. G.; Werk, J. K.; Putman, M. E.

    2017-01-01

    We report the detection of accreting ionized gas at the disk–halo interface of the nearby galaxy M33. We analyze Hubble Space Telescope/Cosmic Origins Spectrograph absorption-line spectra of seven ultraviolet-bright stars evenly distributed across the disk of M33. We find Si iv absorption components consistently redshifted relative to the bulk M33's ISM absorption along all the sightlines. The Si iv detection indicates an enriched, disk-wide, ionized gas inflow toward the disk. This inflow is most likely multi-phase as the redshifted components can also be observed in ions with lower ionization states (e.g., S ii, P ii, Fe ii, Si ii). Kinematic modeling of the inflow is consistent with an accreting layer at the disk–halo interface of M33, which has an accretion velocity of {110}-20+15 {km} {{{s}}}-1 at a distance of {1.5}-1.0+1.0 kpc above the disk. The modeling indicates a total mass of ∼3.9 × 107 M⊙ for the accreting material at the disk–halo interface on the near side of the M33 disk, with an accretion rate of ∼2.9 M⊙ yr‑1. The high accretion rate and the level of metal enrichment suggest the inflow is likely to be the fallback of M33 gas from a galactic fountain and/or the gas pulled loosed during a close interaction between M31 and M33. Our study of M33 is the first to unambiguously reveal the existence of a disk-wide, ionized gas inflow beyond the Milky Way, providing a better understanding of gas accretion in the vicinity of a galaxy disk.

  5. Observations of feedback from radio-quiet quasars - II. Kinematics of ionized gas nebulae

    NASA Astrophysics Data System (ADS)

    Liu, Guilin; Zakamska, Nadia L.; Greene, Jenny E.; Nesvadba, Nicole P. H.; Liu, Xin

    2013-12-01

    The prevalence and energetics of quasar feedback is a major unresolved problem in galaxy formation theory. In this paper, we present Gemini Integral Field Unit observations of ionized gas around 11 luminous, obscured, radio-quiet quasars at z ˜ 0.5 out to ˜15 kpc from the quasar; specifically, we measure the kinematics and morphology of [O III] λ5007 Å emission. The round morphologies of the nebulae and the large line-of-sight velocity widths (with velocities containing 80 per cent of the emission as high as 103 km s-1) combined with relatively small velocity difference across them (from 90 to 520 km s-1) point towards wide-angle quasi-spherical outflows. We use the observed velocity widths to estimate a median outflow velocity of 760 km s-1, similar to or above the escape velocities from the host galaxies. The line-of-sight velocity dispersion declines slightly towards outer parts of the nebulae (by 3 per cent kpc-1 on average). The majority of nebulae show blueshifted excesses in their line profiles across most of their extents, signifying gas outflows. For the median outflow velocity, we find dot{E}_kin between 4 × 1044 and 3 × 1045 erg s-1 and dot{M} between 2 × 103 and 2 × 104 M⊙ yr-1. These values are large enough for the observed quasar winds to have a significant impact on their host galaxies. The median rate of converting bolometric luminosity to kinetic energy of ionized gas clouds is ˜2 per cent. We report four new candidates for `superbubbles' - outflows that may have broken out of the denser regions of the host galaxy.

  6. Probing ionization conditions of Galactic halo gas using H-alpha observations of the Magellanic Stream

    NASA Astrophysics Data System (ADS)

    Barger, Kat; Madsen, Gregory J.; Fox, Andrew; Wakker, Bart P.; Bland-Hawthorn, Jonathan; Nidever, David L.; Lehner, Nicolas; Haffner, L. Matthew; Hill, Alex S.

    2017-01-01

    Galaxy interactions have greatly disturbed and redistributed the gas in the Magellanic System throughout the halos of the Milky Way. Using the Wisconsin H-alpha Mapper (WHAM) telescope, we have completed the highest sensitivity and kinematically resolved emission-line survey of the entire Magellanic Stream. These observations enable us to determine how the ionization conditions change over 100-degrees across the sky, including the region below the South Galactic Pole. We explore the sources of that ionization and find that photoionization from the Milky Way and Magellanic Clouds is insufficient to explain the observed H-alpha emission. We further investigate whether energetic processes associated with the Milky Way's center or interactions with the halo could provide the remaining ionization. The gas in the Magellanic Steam could supply enough gas to maintain or even boost the star formation in the Milky Way, but only if it can survive the journey to the Galaxy's disk.

  7. The SAURON project - XVI. On the sources of ionization for the gas in elliptical and lenticular galaxies

    NASA Astrophysics Data System (ADS)

    Sarzi, Marc; Shields, Joseph C.; Schawinski, Kevin; Jeong, Hyunjin; Shapiro, Kristen; Bacon, Roland; Bureau, Martin; Cappellari, Michele; Davies, Roger L.; de Zeeuw, P. Tim; Emsellem, Eric; Falcón-Barroso, Jesús; Krajnović, Davor; Kuntschner, Harald; McDermid, Richard M.; Peletier, Reynier F.; van den Bosch, Remco C. E.; van de Ven, Glen; Yi, Sukyoung K.

    2010-03-01

    Following our study on the incidence, morphology and kinematics of the ionized gas in early-type galaxies, we now address the question of what is powering the observed nebular emission. To constrain the likely sources of gas excitation, we resort to a variety of ancillary data we draw from complementary information on the gas kinematics, stellar populations and galactic potential from the SAURON data, and use the SAURON-specific diagnostic diagram juxtaposing the [OIII] λ5007/Hβ and [NI] λλ5197, 5200/Hβ line ratios. We find a tight correlation between the stellar surface brightness and the flux of the Hβ recombination line across our sample, which points to a diffuse and old stellar source as the main contributor of ionizing photons in early-type galaxies, with post-asymptotic giant branch (pAGB) stars being still the best candidate based on ionizing balance arguments. The role of AGN photoionization is confined to the central 2-3arcsec of an handful of objects with radio or X-ray cores. OB-stars are the dominant source of photoionization in 10 per cent of the SAURON sample, whereas for another 10 per cent the intense and highly ionized emission is powered by the pAGB population associated to a recently formed stellar subcomponent. Fast shocks are not an important source of ionization for the diffuse nebular emission of early-type galaxies since the required shock velocities can hardly be attained in the potential of our sample galaxies. Finally, in the most massive and slowly or non-rotating galaxies in our sample, which can retain a massive X-ray halo, the finding of a spatial correlation between the hot and warm phases of the interstellar medium (ISM) suggests that the interaction with the hot ISM provides an additional source of ionization besides old ultraviolet-bright stars. This is also supported by a distinct pattern towards lower values of the [OIII]/Hβ ratio. These results lead us to investigate the relative role of stellar and AGN photoionization

  8. Ionized Gas In The Galactic Center: New Observations, Interpretation, And Speculation

    NASA Astrophysics Data System (ADS)

    Irons, Wesley; Lacy, J. H.

    2012-01-01

    We Present new observations of the [Ne II] emission from the ionized gas in Sgr A West with improved resolution and sensitivity. About half of the emission comes from gas with kinematics indicating it is moving on nearly circular orbits in a plane tipped about 25 degrees from the Galactic plane. This plane is consistent with that derived previously for the circumnuclear molecular disk and the northern arm and western arc ionized features. However, unlike most previous studies, we conclude that the ionized gas is not moving along the ionized features, but rather diagonally across them. The observed speeds are close to, but probably somewhat less than expected for orbital motions in the potential of the central black hole and stars. The spatial distribution of the emission is best fitted by a spiral pattern. We discuss possible physical explanations for the spatial distribution and kinematics of the ionized gas, but are unable to find a satisfactory model. This work was supported by NSF grant AST-0607312.

  9. Ionizing wave via high-power HF acceleration

    NASA Astrophysics Data System (ADS)

    Mishin, Evgeny; Pedersen, Todd

    2011-01-01

    Recent ionospheric modification experiments with the 3.6 MW transmitter at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska led to discovery of artificial ionization descending from the nominal interaction altitude in the background F-region ionosphere by ˜60 km. This paper presents a physical model of an ionizing wavefront created by suprathermal electrons accelerated by the HF-excited plasma turbulence.

  10. Black hole mass measurements using ionized gas discs: systematic dust effects

    SciTech Connect

    Baes, Maarten

    2008-10-08

    Using detailed Monte Carlo radiative transfer simulations in realistic models for galactic nuclei, we investigate the influence of interstellar dust in ionized gas discs on the rotation curves and the resulting black hole mass measurements. We find that absorption and scattering by interstellar dust leaves the shape of the rotation curves basically unaltered, but slightly decreases the central slope of the rotation curves. As a result, the ''observed'' black hole masses are systematically underestimated by some 10 to 20% for realistic optical depths. We therefore argue that the systematic effect of dust attenuation should be taken into account when estimating SMBH masses using ionized gas kinematics.

  11. Ionization spectra of highly Stark-shifted rubidium Rydberg states

    NASA Astrophysics Data System (ADS)

    Grimmel, Jens; Stecker, Markus; Kaiser, Manuel; Karlewski, Florian; Torralbo-Campo, Lara; Günther, Andreas; Fortágh, József

    2017-07-01

    We report on the observation and numerical calculation of ionization spectra of highly Stark-shifted Rydberg states of rubidium beyond the classical ionization threshold. In the numerical calculations, a complex absorbing potential (CAP) allows us to predict the energy levels and ionization rates of Rydberg states in this regime. Our approach of adjusting the CAP to the external electric field reduces the number of free parameters from one per resonance to a single one. Furthermore, we have measured the ionization spectra of magneto-optically trapped rubidium atoms which are excited to principal quantum numbers of 43 and 70 at various electric fields. The emerging ions are detected using an ion optics. We find good agreement between the numerically and experimentally obtained spectra.

  12. Construction of a fast ionization chamber for high-rate particle identification

    NASA Astrophysics Data System (ADS)

    Chae, K. Y.; Ahn, S.; Bardayan, D. W.; Chipps, K. A.; Manning, B.; Pain, S. D.; Peters, W. A.; Schmitt, K. T.; Smith, M. S.; Strauss, S. Y.

    2014-07-01

    A new gas-filled ionization chamber for high count rate particle identification has been constructed and commissioned at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). To enhance the response time of the ionization chamber, a design utilizing a tilted entrance window and tilted electrodes was adopted, which is modified from an original design by Kimura et al. [1]. A maximum counting rate of 700 , 000 particles per second has been achieved. The detector has been used for several radioactive beam measurements performed at the HRIBF.

  13. Iodide Chemical Ionization Mass Spectrometry for Trace gas Measurement in Different Environments

    NASA Astrophysics Data System (ADS)

    Eger, Philipp; Phillips, Gavin J.; Crowley, John N.

    2017-04-01

    Chemical Ionization Mass Spectrometry (CIMS) is a versatile and specific technique to simultaneously measure various atmospheric trace gases with good temporal resolution and detection limits in the ppt range (Huey et al., 1995). Our Iodide-CIMS with polonium ionizer and quadrupole mass filter has been used in the past to make measurements of halogenated and organic nitrates and peracetic acid (Phillips et al., 2012; Phillips et al., 2013). Here we present a modified I-CIMS instrument with an electrical discharge ion source that is able to detect a wider variety of gas-phase molecules including peroxyacyl nitrates (PANs), peracetic acid (PAA), ClNO2, HCl, SO2 and organic acids. We show the results of three different field campaigns that took place in maritime, mixed urban/rural and forested environment and outline the instrumental design and the ion chemistry involved. In aged marine air masses (CYPHEX 2014) we measured elevated levels of HCl, ClNO2 and SO2, whereas in the boreal forest (IBAIRN 2016) organic acids resulting from biogenic VOC oxidation were predominant. In mixed urban/rural sites (NOTOMO 2015) both low- and high-NOx conditions were encountered and SO2, PAN, PAA, HCl and ClNO2 were observed.

  14. Ionization heating in rare-gas clusters under intense XUV laser pulses

    SciTech Connect

    Arbeiter, Mathias; Fennel, Thomas

    2010-07-15

    The interaction of intense extreme ultraviolet (XUV) laser pulses ({lambda}=32 nm, I=10{sup 11}-10{sup 14} W/cm{sup 2}) with small rare-gas clusters (Ar{sub 147}) is studied by quasiclassical molecular dynamics simulations. Our analysis supports a very general picture of the charging and heating dynamics in finite samples under short-wavelength radiation that is of relevance for several applications of free-electron lasers. First, up to a certain photon flux, ionization proceeds as a series of direct photoemission events producing a jellium-like cluster potential and a characteristic plateau in the photoelectron spectrum as observed in Bostedt et al. [Phys. Rev. Lett. 100, 133401 (2008)]. Second, beyond the onset of photoelectron trapping, nanoplasma formation leads to evaporative electron emission with a characteristic thermal tail in the electron spectrum. A detailed analysis of this transition is presented. Third, in contrast to the behavior in the infrared or low vacuum ultraviolet range, the nanoplasma energy capture proceeds via ionization heating, i.e., inner photoionization of localized electrons, whereas collisional heating of conduction electrons is negligible up to high laser intensities. A direct consequence of the latter is a surprising evolution of the mean energy of emitted electrons as function of laser intensity.

  15. Pulsed Discharge Helium Ionization Detector for Highly Sensitive Aquametry.

    PubMed

    Mowry, Curtis D; Pimentel, Adam S; Sparks, Elizabeth S; Moorman, Matthew W; Achyuthan, Komandoor E; Manginell, Ronald P

    2016-01-01

    Trace moisture quantitation is crucial in medical, civilian and military applications. Current aquametry technologies are limited by the sample volume, reactivity, or interferences, and/or instrument size, weight, power, cost, and complexity. We report for the first time on the use of a pulsed discharge helium ionization detector (PDHID-D2) (∼196 cm(3)) for the sensitive (limit of detection, 0.047 ng; 26 ppm), linear (r(2) >0.99), and rapid (< 2 min) quantitation of water using a small (0.2 - 5.0 μL) volume of liquid or gas. The relative humidity sensitivity was 0.22% (61.4 ppmv) with a limit of detection of less than 1 ng moisture with gaseous samples. The sensitivity was 10 to 100 to fold superior to competing technologies without the disadvantages inherent to these technologies. The PDHID-D2, due to its small footprint and low power requirement, has good size, weight, and power-portability (SWAPP) factors. The relatively low cost (∼$5000) and commercial availability of the PDHID-D2 makes our technique applicable to highly sensitive aquametry.

  16. Determination of Hexachlorocyclohexane by Gas Chromatography Combined with Femtosecond Laser Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Yang, Xixiang; Imasaka, Tomoko; Li, Adan; Imasaka, Totaro

    2016-12-01

    Structural isomers and enantiomers of hexachlorocyclohexane (HCH) were separated using a chiral column by gas chromatography and quantitatively determined by multiphoton ionization mass spectrometry using an ultraviolet femtosecond laser (200 and 267 nm) as the ionization source. The order of elution of the enantiomers (i.e., (+)-α-HCH and (-)-α-HCH) was predicted from stabilization energies calculated for the complexes using permethylated γ-cyclodextrin as the stationary phase of the column, and the results were compared with the experimental data. The molecular ions observed for HCH were weak, even though they can be ionized through a process of resonance enhanced two-photon ionization at 200 nm. This unfavorable result can be attributed to the dissociation of the molecular ion, as predicted from quantum chemical calculations.

  17. [Determination of acetanilide herbicide residues in tea by gas chromatography-mass spectrometry with two different ionization techniques].

    PubMed

    Shen, Weijian; Xu, Jinzhong; Yang, Wenquan; Shen, Chongyu; Zhao, Zengyun; Ding, Tao; Wu, Bin

    2007-09-01

    An analytical method of solid phase extraction-gas chromatography-mass spectrometry with two different ionization techniques was established for simultaneous determination of 12 acetanilide herbicide residues in tea-leaves. Herbicides were extracted from tea-leaf samples with ethyl acetate. The extract was cleaned-up on an active carbon SPE column connected to a Florisil SPE column. Analytical screening was determined by the technique of gas chromatography (GC)-mass spectrometry (MS) in the selected ion monitoring (SIM) mode with either electron impact ionization (EI) or negative chemical ionization (NCI). It is reliable and stable that the recoveries of all herbicides were in the range from 50% to 110% at three spiked levels, 10 microg/kg, 20 microg/kg and 40 microg/kg, and the relative standard deviations (RSDs) were no more than 10.9%. The two different ionization techniques are complementary as more ion fragmentation information can be obtained from the EI mode while more molecular ion information from the NCI mode. By comparison of the two techniques, the selectivity of NCI-SIM was much better than that of EI-SIM method. The sensitivities of the both techniques were high, the limit of quantitative (LOQ) for each herbicide was no more than 2.0 microg/kg, and the limit of detection (LOD) with NCI-SIM technique was much lower than that of EI-SIM when analyzing herbicides with several halogen atoms in the molecule.

  18. Cosmic ray studies with a gas Cerenkov counter in association with an ionization spectrometer

    NASA Technical Reports Server (NTRS)

    Balasubrahmanyan, V. K.; Ormes, J. F.; Arens, J. F.; Siohan, F.; Simon, M.; Spiegelhauer, H.; Yodh, G. B.

    1980-01-01

    The results from a balloon-borne gas Cerenkov counter (threshold 16.5 GeV/nuc) and an ionization spectrometer are presented. The gas Cerenkov counter provides an absolute energy calibration for the response of the calorimeter for the Z range of 5-26 nuclei of cosmic rays. The contribution of scintillation to the gas Cerenkov pulse height has been obtained by independently selecting particles below the gas Cerenkov threshold using the ionization spectrometer. Energy spectra were derived by minimizing the chi-squared between a Monte Carlo simulated data and flight data. Best fit power laws were determined for C, N, O, Ne, Mg, and Si. The power laws, all consistent with E exp-2.7, are not good fits to the data. A better fit is obtained using the spectrum derived from the spectrometer.

  19. [High Pressure Gas Tanks

    NASA Technical Reports Server (NTRS)

    Quintana, Rolando

    2002-01-01

    Four high-pressure gas tanks, the basis of this study, were especially made by a private contractor and tested before being delivered to NASA Kennedy Space Center. In order to insure 100% reliability of each individual tank the staff at KSC decided to again submit the four tanks under more rigorous tests. These tests were conducted during a period from April 10 through May 8 at KSC. This application further validates the predictive safety model for accident prevention and system failure in the testing of four high-pressure gas tanks at Kennedy Space Center, called Continuous Hazard Tracking and Failure Prediction Methodology (CHTFPM). It is apparent from the variety of barriers available for a hazard control that some barriers will be more successful than others in providing protection. In order to complete the Barrier Analysis of the system, a Task Analysis and a Biomechanical Study were performed to establish the relationship between the degree of biomechanical non-conformities and the anomalies found within the system on particular joints of the body. This relationship was possible to obtain by conducting a Regression Analysis to the previously generated data. From the information derived the body segment with the lowest percentage of non-conformities was the neck flexion with 46.7%. Intense analysis of the system was conducted including Preliminary Hazard Analysis (PHA), Failure Mode and Effect Analysis (FMEA), and Barrier Analysis. These analyses resulted in the identification of occurrences of conditions, which may be becoming hazardous in the given system. These conditions, known as dendritics, may become hazards and could result in an accident, system malfunction, or unacceptable risk conditions. A total of 56 possible dendritics were identified. Work sampling was performed to observe the occurrence each dendritic. The out of control points generated from a Weighted c control chart along with a Pareto analysis indicate that the dendritics "Personnel not

  20. Investigation of ionized metal flux in enhanced high power impulse magnetron sputtering discharges

    SciTech Connect

    Stranak, Vitezslav; Hubicka, Zdenek; Cada, Martin; Drache, Steffen; Hippler, Rainer; Tichy, Milan

    2014-04-21

    The metal ionized flux fraction and production of double charged metal ions Me{sup 2+} of different materials (Al, Cu, Fe, Ti) by High Power Impulse Magnetron Sputtering (HiPIMS) operated with and without a pre-ionization assistance is compared in the paper. The Electron Cyclotron Wave Resonance (ECWR) discharge was employed as the pre-ionization agent providing a seed of charge in the idle time of HiPIMS pulses. A modified grid-free biased quartz crystal microbalance was used to estimate the metal ionized flux fraction ξ. The energy-resolved mass spectrometry served as a complementary method to distinguish particular ion contributions to the total ionized flux onto the substrate. The ratio between densities of doubly Me{sup 2+} and singly Me{sup +} charged metal ions was determined. It is shown that ECWR assistance enhances Me{sup 2+} production with respect of absorbed rf-power. The ECWR discharge also increases the metal ionized flux fraction of about 30% especially in the region of lower pressures. Further, the suppression of the gas rarefaction effect due to enhanced secondary electron emission of Me{sup 2+} was observed.

  1. Cluster chemical ionization for improved confidence level in sample identification by gas chromatography/mass spectrometry.

    PubMed

    Fialkov, Alexander B; Amirav, Aviv

    2003-01-01

    Upon the supersonic expansion of helium mixed with vapor from an organic solvent (e.g. methanol), various clusters of the solvent with the sample molecules can be formed. As a result of 70 eV electron ionization of these clusters, cluster chemical ionization (cluster CI) mass spectra are obtained. These spectra are characterized by the combination of EI mass spectra of vibrationally cold molecules in the supersonic molecular beam (cold EI) with CI-like appearance of abundant protonated molecules, together with satellite peaks corresponding to protonated or non-protonated clusters of sample compounds with 1-3 solvent molecules. Like CI, cluster CI preferably occurs for polar compounds with high proton affinity. However, in contrast to conventional CI, for non-polar compounds or those with reduced proton affinity the cluster CI mass spectrum converges to that of cold EI. The appearance of a protonated molecule and its solvent cluster peaks, plus the lack of protonation and cluster satellites for prominent EI fragments, enable the unambiguous identification of the molecular ion. In turn, the insertion of the proper molecular ion into the NIST library search of the cold EI mass spectra eliminates those candidates with incorrect molecular mass and thus significantly increases the confidence level in sample identification. Furthermore, molecular mass identification is of prime importance for the analysis of unknown compounds that are absent in the library. Examples are given with emphasis on the cluster CI analysis of carbamate pesticides, high explosives and unknown samples, to demonstrate the usefulness of Supersonic GC/MS (GC/MS with supersonic molecular beam) in the analysis of these thermally labile compounds. Cluster CI is shown to be a practical ionization method, due to its ease-of-use and fast instrumental conversion between EI and cluster CI, which involves the opening of only one valve located at the make-up gas path. The ease-of-use of cluster CI is analogous

  2. High Voltage Switch Using Externally Ionized Plasmas.

    DTIC Science & Technology

    1980-04-01

    circuit breakers were not considered because their re- sponse is too slow to meet the on/off and PRF requirements. These constraints narrowed the number of...ELECTRON-BEAM PLASMA SWITCH STUDY 4 2.1 Model Description 4 2.1.1 Plasma and Circuit Models 4 2.1.2 Electron Beam Source Model 8 2.2 Gas Selection...70 "usttloatIon ~in Diutribut 0. is Avail and/or sit pecial 4/ LIST OF ILLUSTRATIONS FIGURE PAGE 1. Circuit Assumed in the Switch Computer Program 6

  3. Particle-in-Cell Simulations of Gas Ionization by Short Intense Laser Pulses

    NASA Astrophysics Data System (ADS)

    Dimitrov, Dimitre; Bruhwiler, David; Leemans, Wim; Esarey, Eric; Catravas, Palma; Toth, Csaba; Shadwick, Brad; Cary, John; Giacone, Rodolfo; Verboncoeur, John; Mardahl, Peter

    2001-10-01

    Laser wakefield accelerators (LWFA) can generate accelerating gradients orders of magnitude larger than those obtained in conventional metal structures. In many LWFA experiments, the leading edge of the short, intense laser pulse completely ionizes a background neutral gas. An important question is the effect of laser ionization on the evolution of the laser pulse. Dispersive effects can modify the length and shape of the pulse as it propagates through the gas/plasma. Pulse steepening or break-up can affect the growth of the plasma wake. We will present particle-in-cell simulations using the ADK [M.V. Ammosov et al., Sov. Phys. JETP 64, p. 1191 (1986)] tunneling ionization model in the XOOPIC [J.P. Verboncoeur et al., J. Comp. Phys. 104, p. 321 (1993)] code. These simulations will be compared with experimental LWFA results from the l'OASIS laboratory of LBNL [W.P. Leemans et al., Phys. Plasmas 8, p. 2510 (2001)].

  4. Properties of a weakly ionized NO gas sensor based on multi-walled carbon nanotubes

    SciTech Connect

    Zhang, Jingyuan; Zhang, Yong Pan, Zhigang; Yang, Shuang; Shi, Jinghui; Li, Shengtao; Min, Daomin; Wang, Xiaohua; Liu, Dingxin; Yang, Aijun; Li, Xin

    2015-08-31

    Nitric oxide NO is one of the major targets for environmental monitoring, but the existing NO sensors are limited by their low sensitivity and narrow test range. Here, a NO gas sensor employing multiwalled carbon nanotubes (MWCNTs) was fabricated, and its properties in NO–N{sub 2} mixture were investigated from both emission and ionization. The current I{sub e} passing through the nanotubes cathode was found to decrease with increasing NO concentration and increase linearly in different slopes with the extracting voltage U{sub e}. It is shown that the Schottky barrier of the MWCNTs calculated by I{sub e} increased with NO concentration due to the adsorption of NO gas, which restrained the electron emission and consequently weakened the ionization. The positive ion currents I{sub c} passing through the collecting electrode at different voltages of U{sub e} were found to monotonically decrease with increasing NO concentration, which was induced by both of the reduced electron emission and the consumption of the two excited metastable states N{sub 2}(A{sup 3}∑{sub u}{sup +}) and N{sub 2}(a′{sup 1}∑{sub u}{sup −}) by NO. The sensor exhibited high sensitivity at the low temperature of 30 °C. The calculated conductivity was found to be able to take place of I{sub c} for NO detection in a wide voltage range of 80–150 V U{sub e}.

  5. Mapping the gas kinematics and ionization structure of four ultraluminous IRAS galaxies

    NASA Astrophysics Data System (ADS)

    Wilman, R. J.; Crawford, C. S.; Abraham, R. G.

    1999-10-01

    We present a study of the morphology, kinematics and ionization structure of the extended emission-line regions in four intermediate-redshift (0.118gas kinematics in the hyperluminous system IRAS F20460+1925 lack coherent structure, with a full width at half-maximum (FWHM) >1000kms-1 within 1arcsec of the nucleus, suggesting that any merger is well-advanced. Emission-line intensity ratios point to active galactic nucleus (AGN) photoionization for the excitation of this gas at the systemic velocity. An isolated blob ~8kpc from the nucleus with a much smaller velocity dispersion may lie in a structure similar to the photoionization cones seen in lower-luminosity objects. A second, spatially unresolved, narrow-line component is also present on nucleus, blueshifted by ~=990kms-1 from the systemic and plausibly powered by photoionizing shocks. IRAS F23060+0505 has more ordered kinematics, with a region of increased FWHM coincident with the blue half of a dipolar velocity field. The systemic velocity rotation curve is asymmetric in appearance, as a result either of the on-going merger or of nuclear dust obscuration. From a higher-resolution ISIS spectrum, we attribute the blue asymmetry in the narrow-line profiles to a spatially resolved nuclear outflow. Emission-line intensity ratios suggest shock+precursor ionization for the systemic component, consistent with the X-ray view of a heavily obscured AGN. The lower-luminosity objects IRAS F01217+0122 and F01003-2238 complete the sample. The former has a featureless velocity field with a high FWHM, a high-ionization AGN spectrum and a ~1Gyr old starburst continuum. IRAS F01003-2238 has a dipolar velocity field and an Hii region emission-line spectrum with a strong blue continuum. After correction for intrinsic extinction, the latter can be reproduced with ~107 O5 stars, sufficient to power the bolometric luminosity of the

  6. High molecular weight non-polar hydrocarbons as pure model substances and in motor oil samples can be ionized without fragmentation by atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Hourani, Nadim; Kuhnert, Nikolai

    2012-10-15

    High molecular weight non-polar hydrocarbons are still difficult to detect by mass spectrometry. Although several studies have targeted this problem, lack of good self-ionization has limited the ability of mass spectrometry to examine these hydrocarbons. Failure to control ion generation in the atmospheric pressure chemical ionization (APCI) source hampers the detection of intact stable gas-phase ions of non-polar hydrocarbon in mass spectrometry. Seventeen non-volatile non-polar hydrocarbons, reported to be difficult to ionize, were examined by an optimized APCI methodology using nitrogen as the reagent gas. All these analytes were successfully ionized as abundant and intact stable [M-H](+) ions without the use of any derivatization or adduct chemistry and without significant fragmentation. Application of the method to real-life hydrocarbon mixtures like light shredder waste and car motor oil was demonstrated. Despite numerous reports to the contrary, it is possible to ionize high molecular weight non-polar hydrocarbons by APCI, omitting the use of additives. This finding represents a significant step towards extending the applicability of mass spectrometry to non-polar hydrocarbon analyses in crude oil, petrochemical products, waste or food. Copyright © 2012 John Wiley & Sons, Ltd.

  7. Ammonia quantitative analysis model based on miniaturized Al ionization gas sensor and non-linear bistable dynamic model

    PubMed Central

    Ma, Rongfei

    2015-01-01

    In this paper, ammonia quantitative analysis based on miniaturized Al ionization gas sensor and non-linear bistable dynamic model was proposed. Al plate anodic gas-ionization sensor was used to obtain the current-voltage (I-V) data. Measurement data was processed by non-linear bistable dynamics model. Results showed that the proposed method quantitatively determined ammonia concentrations. PMID:25975362

  8. Ammonia quantitative analysis model based on miniaturized Al ionization gas sensor and non-linear bistable dynamic model.

    PubMed

    Ma, Rongfei

    2015-01-01

    In this paper, ammonia quantitative analysis based on miniaturized Al ionization gas sensor and non-linear bistable dynamic model was proposed. Al plate anodic gas-ionization sensor was used to obtain the current-voltage (I-V) data. Measurement data was processed by non-linear bistable dynamics model. Results showed that the proposed method quantitatively determined ammonia concentrations.

  9. Limitations of a residual gas ionization beam profile monitor for the SSC Collider

    SciTech Connect

    Meinke, R.; Nexsen, W.; Tsyganov, E.; Zinchenko, A.

    1992-11-01

    A residual gas ionization beam profile monitor for the superconducting Super Collider is considered in detail using the Monte Carlo simulation code. It is shown that a good spatial resolution could be obtained using a combination of strong electrical and magnetic fields.

  10. 40 CFR 1065.267 - Gas chromatograph with a flame ionization detector.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Gas chromatograph with a flame ionization detector. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon...

  11. 40 CFR 1065.267 - Gas chromatograph with a flame ionization detector.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Gas chromatograph with a flame ionization detector. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon...

  12. 40 CFR 1065.267 - Gas chromatograph with a flame ionization detector.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Gas chromatograph with a flame ionization detector. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon...

  13. Kinematics of the ionized gas in the Local Group irregular galaxy IC 1613

    NASA Astrophysics Data System (ADS)

    Valdez-Gutiérrez, M.; Rosado, M.; Georgiev, L.; Borissova, J.; Kurtev, R.

    2001-01-01

    We present Hα and [S Ii] observations for the Local Group irregular galaxy IC 1613 using the PUMA scanning Fabry-Perot interferometer. Our goal is to analyze the kinematics of the ionized gas in the complex sample of superbubbles located in the whole extension of our field (10\\arcmin ), which includes most of the optical emission of this galaxy, and to study the inter-relationship between young stellar associations and nebulae based on a previous study that we have made on the stellar associations of the central region of this galaxy. The ionized gas in this galaxy is distributed in classical H Ii regions and in a series of superbubbles (also called giant shells) covering a large fraction of the optical extent of the galaxy. We present a catalog of kinematical properties of both the H Ii regions of this galaxy and the superbubbles. We have also compared the kinematics of the ionized gas in H Ii regions to search for possible dynamic differences between neutral and ionized gas.

  14. Dust and ionized gas in active radio elliptical galaxies

    NASA Technical Reports Server (NTRS)

    Forbes, D. A.; Sparks, W. B.; Macchetto, F. D.

    1990-01-01

    The authors present broad and narrow bandwidth imaging of three southern elliptical galaxies which have flat-spectrum active radio cores (NGC 1052, IC 1459 and NGC 6958). All three contain dust and extended low excitation optical line emission, particularly extensive in the case of NGC 1052 which has a large H alpha + (NII) luminosity. Both NGC 1052 and IC 1459 have a spiral morphology in emission-line images. All three display independent strong evidence that a merger or infall event has recently occurred, i.e., extensive and infalling HI gas in NGC 1052, a counter-rotating core in IC 1459 and Malin-Carter shells in NGC 6958. This infall event is the most likely origin for the emission-line gas and dust, and the authors are currently investigating possible excitation mechanisms (Sparks et al. 1990).

  15. Molecular and ionized gas kinematics in the GC Radio Arc

    NASA Astrophysics Data System (ADS)

    Butterfield, N.; Lang, C. C.; Mills, E. A. C.; Ludovici, D.; Ott, J.; Morris, M. R.

    2017-01-01

    We present NH3 and H64α+H63α VLA observations of the Radio Arc region, including the M0.20 - 0.033 and G0.10 - 0.08 molecular clouds. These observations suggest the two velocity components of M0.20 - 0.033 are physically connected in the south. Additional ATCA observations suggest this connection is due to an expanding shell in the molecular gas, with the centroid located near the Quintuplet cluster. The G0.10 - 0.08 molecular cloud has little radio continuum, strong molecular emission, and abundant CH3OH masers, similar to a nearby molecular cloud with no star formation: M0.25+0.01. These features detected in G0.10 - 0.08 suggest dense molecular gas with no signs of current star formation.

  16. Ionized gas diagnostics from protoplanetary discs in the Orion nebula and the abundance discrepancy problem

    NASA Astrophysics Data System (ADS)

    Mesa-Delgado, A.; Núñez-Díaz, M.; Esteban, C.; García-Rojas, J.; Flores-Fajardo, N.; López-Martín, L.; Tsamis, Y. G.; Henney, W. J.

    2012-10-01

    We present results from integral field spectroscopy of a field located near the Trapezium Cluster using the Potsdam Multi-Aperture Spectrophotometer (PMAS). The observed field contains a variety of morphological structures: five externally ionized protoplanetary discs (also known as proplyds), the high-velocity jet HH 514 and a bowshock. Spatial distribution maps are obtained for different emission line fluxes, the c(Hβ) extinction coefficient, electron densities and temperatures, ionic abundances of different ions from collisionally excited lines (CELs), C2 + and O2 + abundances from recombination lines (RLs) and the abundance discrepancy factor of O2 +, ADF(O2 +). We distinguish the three most prominent proplyds (177-341, 170-337 and 170-334) and analyse their impact on the spatial distributions of the above mentioned quantities. We find that collisional de-excitation has a major influence on the line fluxes in the proplyds. If this is not properly accounted for then physical conditions deduced from commonly used line ratios will be in error, leading to unreliable chemical abundances for these objects. We obtain the intrinsic emission of the proplyds 177-341, 170-337 and 170-334 by a direct subtraction of the background emission, though the last two present some background contamination due to their small sizes. A detailed analysis of 177-341 spectra making use of suitable density diagnostics reveals the presence of high-density gas (3.8 × 105 cm-3) in contrast to the typical values observed in the background gas of the nebula (3800 cm-3). We also explore how the background subtraction could be affected by the possible opacity of the proplyd and its effect on the derivation of physical conditions and chemical abundances of the proplyd 177-341. We construct a physical model for the proplyd 177-341 finding a good agreement between the predicted and observed line ratios. Finally, we find that the use of reliable physical conditions returns an ADF(O2 +) about zero

  17. Shells, holes, worms, high-velocity gas and the z-distribution of gas in galaxies.

    NASA Astrophysics Data System (ADS)

    Rand, R. J.

    The author gives an overview of the current observational understanding of vertically extended gas components in spiral galaxies and the various phenomena which come under such names as shells, holes, worms, and high-velocity gas. For the most part, the focus is on recent high-resolution interferometric studies. The author concentrates on cold gas, and briefly on warm ionized gas, in the Milky Way and a few nearby spirals. Along the way, it is seen how phenomena such as worms and shells may be related to the formation and maintenance of the vertically extended components.

  18. Electron impact ionization of highly charged lithiumlike ions

    SciTech Connect

    Wong, K L

    1992-10-01

    Electron impact ionization cross sections can provide valuable information about the charge-state and power balance of highly charged ions in laboratory and astrophysical plasmas. In the present work, a novel technique based on x-ray measurements has been used to infer the ionization cross section of highly charged lithiumlike ions on the Livermore electron beam ion trap. In particular, a correspondence is established between an observed x ray and an ionization event. The measurements are made at one energy corresponding to approximately 2.3 times the threshold energy for ionization of lithiumlike ions. The technique is applied to the transition metals between Z=22 (titanium, Ti[sup 19+]) and Z=26 (iron, Fe[sup 23+]) and to Z=56 (barium, Ba[sup 53+]). The results for the transition metals, which have an estimated 17-33% uncertainty, are in good overall agreement with a relativistic distorted-wave calculation. However, less good agreement is found for barium, which has a larger uncertainty. Methods for properly accounting for the polarization in the x-ray intensities and for inferring the charge-state abundances from x-ray observations, which were developed for the ionization measurements, as well as an x-ray model that assists in the proper interpretation of the data are also presented.

  19. Ionization of highly excited helium atoms in an electric field

    SciTech Connect

    van de Water, W.; Mariani, D.R.; Koch, P.M.

    1984-11-01

    We present detailed measurements of ionization of highly excited triplet helium atoms in a static electric field. The atoms were prepared in states with energy E close to the saddle-point threshold E = -2(F(a.u.))/sup 1/2/. The electric field F was sufficiently strong for the states to be characterized by total spin S and absolute value of the magnetic quantum number M/sub L/. For M/sub L/ = 0 states the experiments measured ionization properties of adiabatic states. In another case, Vertical BarM/sub L/Vertical Bar = 2, they predominantly measured those of diabatic states. In both cases the ionization rate was found to be a highly nonmonotonic function of the field strength. The observations are analyzed in terms of a theory of the helium density of states in an electric field. A companion paper (D. A. Harmin, Phys. Rev. A 30, 2413 (1984)) develops in detail the general theory, which uses quantum defects to parametrize the effect of the core interaction. The agreement between measured and calculated ionization curves is good, indicating that the field ionization of a nonhydrogenic atom can now be understood in a detailed, quantitative, and predictive sense.

  20. An Ultra-Trace Analysis Technique for SF6 Using Gas Chromatography with Negative Ion Chemical Ionization Mass Spectrometry.

    PubMed

    Jong, Edmund C; Macek, Paul V; Perera, Inoka E; Luxbacher, Kray D; McNair, Harold M

    2015-07-01

    Sulfur hexafluoride (SF6) is widely used as a tracer gas because of its detectability at low concentrations. This attribute of SF6 allows the quantification of both small-scale flows, such as leakage, and large-scale flows, such as atmospheric currents. SF6's high detection sensitivity also facilitates greater usage efficiency and lower operating cost for tracer deployments by reducing quantity requirements. The detectability of SF6 is produced by its high molecular electronegativity. This property provides a high potential for negative ion formation through electron capture thus naturally translating to selective detection using negative ion chemical ionization mass spectrometry (NCI-MS). This paper investigates the potential of using gas chromatography (GC) with NCI-MS for the detection of SF6. The experimental parameters for an ultra-trace SF6 detection method utilizing minimal customizations of the analytical instrument are detailed. A method for the detection of parts per trillion (ppt) level concentrations of SF6 for the purpose of underground ventilation tracer gas analysis was successfully developed in this study. The method utilized a Shimadzu gas chromatography with negative ion chemical ionization mass spectrometry system equipped with an Agilent J&W HP-porous layer open tubular column coated with an alumina oxide (Al2O3) S column. The method detection limit (MDL) analysis as defined by the Environmental Protection Agency of the tracer data showed the method MDL to be 5.2 ppt.

  1. A compact fast ionization gauge for in situ measurement of high-density neutral flow dynamics

    NASA Astrophysics Data System (ADS)

    Weber, T. E.; Intrator, T. P.

    2014-04-01

    A compact ionization gauge has been developed to carry out in situ measurements of high density (1020-1022 m-3) neutral gas flow dynamics with high temporal and spatial resolution. Key design aspects are discussed including gauge sensitivity and time response scaling with decreased probe dimensions, high-pressure operation, improved driver circuit bandwidth, and techniques for constructing a miniaturized probe head. Gas adsorption was discovered to significantly alter emission current and gauge sensitivity over timescales of several seconds. This effect must be taken into consideration when making time-resolved, high-density measurements. Over short timescales gauge response was predicted by scaling the sensitivity of a nominal Bayard-Alpert gauge to account for variations in probe dimensions and species-dependent ionization cross-section. Time-resolved neutral density profiles have been acquired in the Magnetized Shock Experiment at Los Alamos National Laboratory, providing data on the initial conditions of the ionization, plasmoid formation, and translation processes. It is shown that the desired density profiles can be achieved using a dynamic gas fill and that density can be scaled independently of the spatial profile.

  2. A compact fast ionization gauge for in situ measurement of high-density neutral flow dynamics.

    PubMed

    Weber, T E; Intrator, T P

    2014-04-01

    A compact ionization gauge has been developed to carry out in situ measurements of high density (10(20)-10(22) m(-3)) neutral gas flow dynamics with high temporal and spatial resolution. Key design aspects are discussed including gauge sensitivity and time response scaling with decreased probe dimensions, high-pressure operation, improved driver circuit bandwidth, and techniques for constructing a miniaturized probe head. Gas adsorption was discovered to significantly alter emission current and gauge sensitivity over timescales of several seconds. This effect must be taken into consideration when making time-resolved, high-density measurements. Over short timescales gauge response was predicted by scaling the sensitivity of a nominal Bayard-Alpert gauge to account for variations in probe dimensions and species-dependent ionization cross-section. Time-resolved neutral density profiles have been acquired in the Magnetized Shock Experiment at Los Alamos National Laboratory, providing data on the initial conditions of the ionization, plasmoid formation, and translation processes. It is shown that the desired density profiles can be achieved using a dynamic gas fill and that density can be scaled independently of the spatial profile.

  3. Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): review.

    PubMed

    Li, Du-Xin; Gan, Lin; Bronja, Amela; Schmitz, Oliver J

    2015-09-03

    Although the coupling of GC/MS with atmospheric pressure ionization (API) has been reported in 1970s, the interest in coupling GC with atmospheric pressure ion source was expanded in the last decade. The demand of a "soft" ion source for preserving highly diagnostic molecular ion is desirable, as compared to the "hard" ionization technique such as electron ionization (EI) in traditional GC/MS, which fragments the molecule in an extensive way. These API sources include atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), atmospheric pressure laser ionization (APLI), electrospray ionization (ESI) and low temperature plasma (LTP). This review discusses the advantages and drawbacks of this analytical platform. After an introduction in atmospheric pressure ionization the review gives an overview about the history and explains the mechanisms of various atmospheric pressure ionization techniques used in combination with GC such as APCI, APPI, APLI, ESI and LTP. Also new developments made in ion source geometry, ion source miniaturization and multipurpose ion source constructions are discussed and a comparison between GC-FID, GC-EI-MS and GC-API-MS shows the advantages and drawbacks of these techniques. The review ends with an overview of applications realized with GC-API-MS.

  4. Dissociation and ionization of molecular gas in the spiral arms of M51

    NASA Technical Reports Server (NTRS)

    Lees, J. F.; Lo, K. Y.

    1990-01-01

    Researchers derive the star formation rate and efficiency in the arm and interarm regions of M51 from observations of the molecular (Lo et al. 1987) and ionized (van der Hulst et al. 1988) phases of the interstellar medium, and show that the HI observations of Tilanus and Allen (1989) are consistent with dissociation of molecular gas by these young, massive stars if n sub H greater than or equal to 200 cm (-2). However, these stars are not able to dissociate or ionize all the gas, and at least 60 percent must remain molecular in the interarm regions. The efficiency of star formation in M51 seems to be similar to that in the Galaxy, and does not appear to be enhanced in the spiral arms. Therefore, the effect of the strong density wave may be only to concentrate the gas, and hence the young stars, to the arm regions.

  5. Numerical studies of the behavior of ionized residual gas in an energy recovering linac

    NASA Astrophysics Data System (ADS)

    Pöplau, Gisela; van Rienen, Ursula; Meseck, Atoosa

    2015-04-01

    Next generation light sources such as energy recovering linacs (ERLs) are highly sensitive to instabilities due to ionized residual gas, which must be mitigated for successful operation. Vacuum pumps are insufficient for removal of the ions, as the ions are trapped by the beam's electrical potential. Two effective measures are (i) introducing clearing gaps in the bunch train, and (ii) installing clearing electrodes which pull out the trapped ions from the electrical potential of the beam. In this paper, we present numerical studies on the behavior of ion clouds that interact with bunch trains in an ERL taking into account the effects of the clearing gaps and clearing electrodes. We present simulations with different compositions of the residual gas. Simulations are done using the MOEVE PIC Tracking software package developed at Rostock University, which has been upgraded to include the behavior of ion clouds in the environment of additional electromagnetic fields, such as generated by clearing electrodes. The simulations use the parameters of the Berlin Energy Recovery Linac Project (bERLinPro) to allow for the deduction of appropriate measures for bERLinPro 's design and operation.

  6. Hose Instability and Wake Generation By An Intense Electron Beam in a Self-Ionized Gas

    SciTech Connect

    Deng, S.; Barnes, C.D.; Clayton, C.E.; O'Connell, C.; Decker, F.J.; Fonseca, R.A.; Huang, C.; Hogan, M.J.; Iverson, R.; Johnson, D.K.; Joshi, C.; Katsouleas, T.; Krejcik, P.; Lu, W.; Mori, W.B.; Muggli, P.; Oz, E.; Tsung, F.; Walz, D.; Zhou, M.; /Southern California U. /UCLA /SLAC

    2006-04-12

    The propagation of an intense relativistic electron beam through a gas that is self-ionized by the beam's space charge and wakefields is examined analytically and with 3D particle-in-cell simulations. Instability arises from the coupling between a beam and the offset plasma channel it creates when it is perturbed. The traditional electron hose instability in a preformed plasma is replaced with this slower growth instability depending on the radius of the ionization channel compared to the electron blowout radius. A new regime for hose stable plasma wakefield acceleration is suggested.

  7. Transfer ionization in collisions with a fast highly charged ion.

    PubMed

    Voitkiv, A B

    2013-07-26

    Transfer ionization in fast collisions between a bare ion and an atom, in which one of the atomic electrons is captured by the ion whereas another one is emitted, crucially depends on dynamic electron-electron correlations. We show that in collisions with a highly charged ion a strong field of the ion has a very profound effect on the correlated channels of transfer ionization. In particular, this field weakens (strongly suppresses) electron emission into the direction opposite (perpendicular) to the motion of the ion. Instead, electron emission is redirected into those parts of the momentum space which are very weakly populated in fast collisions with low charged ions.

  8. Measuring Ionization in Highly Compressed, Near-Degenerate Plasmas

    NASA Astrophysics Data System (ADS)

    Doeppner, Tilo; Kraus, D.; Neumayer, P.; Bachmann, B.; Collins, G. W.; Divol, L.; Kritcher, A.; Landen, O. L.; Pak, A.; Weber, C.; Fletcher, L.; Glenzer, S. H.; Falcone, R. W.; Saunders, A.; Chapman, D.; Baggott, R.; Gericke, D. O.; Yi, A.

    2016-10-01

    A precise knowledge of ionization at given temperature and density is required to accurately model compressibility and heat capacity of materials at extreme conditions. We use x-ray Thomson scattering to characterize the plasma conditions in plastic and beryllium capsules near stagnation in implosion experiments at the National Ignition Facility. We expect the capsules to be compressed to more than 20x and electron densities approaching 1025 cm-3, corresponding to a Fermi energy of 170 eV. Zinc Heα x-rays (9 keV) scattering at 120° off the plasma yields high sensitivity to K-shell ionization, while at the same time constraining density and temperature. We will discuss recent results in the context of ionization potential depression at these extreme conditions. This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  9. Isobutane Made Practical as a Reagent Gas for Chemical Ionization Mass Spectrometry.

    PubMed

    Newsome, G Asher; Steinkamp, F Lucus; Giordano, Braden C

    2016-11-01

    As a reagent gas for positive- and negative-mode chemical ionization mass spectrometry (CI-MS), isobutane (i-C4H10) produces superior analyte signal abundance to methane. Isobutane has never been widely adopted for CI-MS because it fouls the ion source more rapidly and produces positive CI spectra that are more strongly dependent on reagent gas pressure compared with methane. Isobutane was diluted to various concentrations in argon for use as a reagent gas with an unmodified commercial gas chromatograph-mass spectrometer. Analyte spectra were directly compared using methane, isobutane, and isobutane/argon mixtures. A mixture of 10% i-C4H10 in argon produced twice the positive-mode analyte signal of methane, equal to pure isobutane, and reduced spectral dependence on reagent gas pressure. Electron capture negative chemical ionization using 1% i-C4H10 in argon tripled analyte signal compared with methane and was reproducible, unlike pure isobutane. The operative lifetime of the ion source using isobutane/argon mixtures was extended exponentially compared with pure isobutane, producing stable and reproducible CI signal throughout. By diluting the reagent gas in an inert buffer gas, isobutane CI-MS experiments were made as practical to use as methane CI-MS experiments but with superior analytical performance. Graphical Abstract ᅟ.

  10. Isobutane Made Practical as a Reagent Gas for Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Newsome, G. Asher; Steinkamp, F. Lucus; Giordano, Braden C.

    2016-11-01

    As a reagent gas for positive- and negative-mode chemical ionization mass spectrometry (CI-MS), isobutane ( i-C4H10) produces superior analyte signal abundance to methane. Isobutane has never been widely adopted for CI-MS because it fouls the ion source more rapidly and produces positive CI spectra that are more strongly dependent on reagent gas pressure compared with methane. Isobutane was diluted to various concentrations in argon for use as a reagent gas with an unmodified commercial gas chromatograph-mass spectrometer. Analyte spectra were directly compared using methane, isobutane, and isobutane/argon mixtures. A mixture of 10% i-C4H10 in argon produced twice the positive-mode analyte signal of methane, equal to pure isobutane, and reduced spectral dependence on reagent gas pressure. Electron capture negative chemical ionization using 1% i-C4H10 in argon tripled analyte signal compared with methane and was reproducible, unlike pure isobutane. The operative lifetime of the ion source using isobutane/argon mixtures was extended exponentially compared with pure isobutane, producing stable and reproducible CI signal throughout. By diluting the reagent gas in an inert buffer gas, isobutane CI-MS experiments were made as practical to use as methane CI-MS experiments but with superior analytical performance.

  11. Mapping the central regions of active galactic nuclei using high-ionization lines

    NASA Astrophysics Data System (ADS)

    Rodríguez-Ardila, A. R.; Prieto, M. A.; Mazzalay, X.; Mason, R.

    2017-07-01

    We present results of an ongoing work aimed at studying coronal lines (CLs) in a sample of nearby AGNs. The data allowed us to resolve and map the extension of the CL gas and compare it to that emitting low- to mid-ionization lines. The very good match between the radio emission and the CLR suggest that part of the high-ionization gas is jet-driven. Photoionization models, where the AGN is the only source of energy input fail at reproducing the observed line ratios, mainly at distances larger than 60 pc from the centre. We discuss other processes that should be at work to enhance this energetic emission. Our results suggest that coronal lines in AGNs are unambiguous signature of feedback processes in these sources.

  12. Cosmic distribution of highly ionized metals and their physical conditions in the EAGLE simulations

    NASA Astrophysics Data System (ADS)

    Rahmati, Alireza; Schaye, Joop; Crain, Robert A.; Oppenheimer, Benjamin D.; Schaller, Matthieu; Theuns, Tom

    2016-06-01

    We study the distribution and evolution of highly ionized intergalactic metals in the Evolution and Assembly of Galaxies and their Environment (EAGLE) cosmological, hydrodynamical simulations. EAGLE has been shown to reproduce a wide range of galaxy properties while its subgrid feedback was calibrated without considering gas properties. We compare the predictions for the column density distribution functions (CDDFs) and cosmic densities of Si IV, C IV, N V, O VI and Ne VIII absorbers with observations at redshift z = 0 to ˜6 and find reasonable agreement, although there are some differences. We show that the typical physical densities of the absorbing gas increase with column density and redshift, but decrease with the ionization energy of the absorbing ion. The typical metallicity increases with both column density and time. The fraction of collisionally ionized metal absorbers increases with time and ionization energy. While our results show little sensitivity to the presence or absence of AGN feedback, increasing/decreasing the efficiency of stellar feedback by a factor of 2 substantially decreases/increases the CDDFs and the cosmic densities of the metal ions. We show that the impact of the efficiency of stellar feedback on the CDDFs and cosmic densities is largely due to its effect on the metal production rate. However, the temperatures of the metal absorbers, particularly those of strong O VI, are directly sensitive to the strength of the feedback.

  13. Diffuse gas in retired galaxies: nebular emission templates and constraints on the sources of ionization

    NASA Astrophysics Data System (ADS)

    Johansson, Jonas; Woods, Tyrone E.; Gilfanov, Marat; Sarzi, Marc; Chen, Yan-Mei; Oh, Kyuseok

    2016-10-01

    We present emission-line templates for passively-evolving (`retired') galaxies, useful for investigation of the evolution of the interstellar medium in these galaxies, and characterization of their high-temperature source populations. The templates are based on high signal-to-noise (>800) co-added spectra (3700-6800 Å) of ˜11 500 gas-rich Sloan Digital Sky Survey galaxies devoid of star formation and active galactic nuclei. Stacked spectra are provided for the entire sample and sub-samples binned by mean stellar age. In our previous paper, Johansson et al., these spectra provided the first measurements of the He II 4686 Å line in passively-evolving galaxies, and the observed He II/Hβ ratio constrained the contribution of accreting white dwarfs (the `single-degenerate' scenario) to the Type Ia supernova rate. In this paper, the full range of unambiguously detected emission lines are presented. Comparison of the observed [O I] 6300 Å/Hα ratio with photoionization models further constrains any high-temperature single-degenerate scenario for Type Ia supernovae (with 1.5 ≲ T/105 K ≲ 10) to ≲3-6 per cent of the observed rate in the youngest age bin (i.e. highest SN Ia rate). Hence, for the same temperatures, in the presence of an ambient population of post-asymptotic giant branch stars, we exclude additional high-temperature sources with a combined ionizing luminosity of ≈1.35 × 1030 L⊙/M⊙,* for stellar populations with mean ages of 1-4 Gyr. Furthermore, we investigate the extinction affecting both the stellar and nebular continuum. The latter shows about five times higher values. This contradicts isotropically distributed dust and gas that renders similar extinction values for both cases.

  14. Tracing kinematic (mis)alignments in CALIFA merging galaxies. Stellar and ionized gas kinematic orientations at every merger stage

    NASA Astrophysics Data System (ADS)

    Barrera-Ballesteros, J. K.; García-Lorenzo, B.; Falcón-Barroso, J.; van de Ven, G.; Lyubenova, M.; Wild, V.; Méndez-Abreu, J.; Sánchez, S. F.; Marquez, I.; Masegosa, J.; Monreal-Ibero, A.; Ziegler, B.; del Olmo, A.; Verdes-Montenegro, L.; García-Benito, R.; Husemann, B.; Mast, D.; Kehrig, C.; Iglesias-Paramo, J.; Marino, R. A.; Aguerri, J. A. L.; Walcher, C. J.; Vílchez, J. M.; Bomans, D. J.; Cortijo-Ferrero, C.; González Delgado, R. M.; Bland-Hawthorn, J.; McIntosh, D. H.; Bekeraitė, S.

    2015-10-01

    We present spatially resolved stellar and/or ionized gas kinematic properties for a sample of 103 interacting galaxies, tracing all merger stages: close companions, pairs with morphological signatures of interaction, and coalesced merger remnants. In order to distinguish kinematic properties caused by a merger event from those driven by internal processes, we compare our galaxies with a control sample of 80 non-interacting galaxies. We measure for both the stellar and the ionized gas components the major (projected) kinematic position angles (PAkin, approaching and receding) directly from the velocity distributions with no assumptions on the internal motions. This method also allow us to derive the deviations of the kinematic PAs from a straight line (δPAkin). We find that around half of the interacting objects show morpho-kinematic PA misalignments that cannot be found in the control sample. In particular, we observe those misalignments in galaxies with morphological signatures of interaction. On the other hand, thelevel of alignment between the approaching and receding sides for both samples is similar, with most of the galaxies displaying small misalignments. Radial deviations of the kinematic PA orientation from a straight line in the stellar component measured by δPAkin are large for both samples. However, for a large fraction of interacting galaxies the ionized gas δPAkin is larger than the typical values derived from isolated galaxies (48%), indicating that this parameter is a good indicator to trace the impact of interaction and mergers in the internal motions of galaxies. By comparing the stellar and ionized gas kinematic PA, we find that 42% (28/66) of the interacting galaxies have misalignments larger than 16°, compared to 10% from the control sample. Our results show the impact of interactions in the motion of stellar and ionized gas as well as the wide the variety of their spatially resolved kinematic distributions. This study also provides a local

  15. Generation of naphthoquinone radical anions by electrospray ionization: solution, gas-phase, and computational chemistry studies.

    PubMed

    Vessecchi, Ricardo; Naal, Zeki; Lopes, José N C; Galembeck, Sérgio E; Lopes, Norberto P

    2011-06-02

    Radical anions are present in several chemical processes, and understanding the reactivity of these species may be described by their thermodynamic properties. Over the last years, the formation of radical ions in the gas phase has been an important issue concerning electrospray ionization mass spectrometry studies. In this work, we report on the generation of radical anions of quinonoid compounds (Q) by electrospray ionization mass spectrometry. The balance between radical anion formation and the deprotonated molecule is also analyzed by influence of the experimental parameters (gas-phase acidity, electron affinity, and reduction potential) and solvent system employed. The gas-phase parameters for formation of radical species and deprotonated species were achieved on the basis of computational thermochemistry. The solution effects on the formation of radical anion (Q(•-)) and dianion (Q(2-)) were evaluated on the basis of cyclic voltammetry analysis and the reduction potentials compared with calculated electron affinities. The occurrence of unexpected ions [Q+15](-) was described as being a reaction between the solvent system and the radical anion, Q(•-). The gas-phase chemistry of the electrosprayed radical anions was obtained by collisional-induced dissociation and compared to the relative energy calculations. These results are important for understanding the formation and reactivity of radical anions and to establish their correlation with the reducing properties by electrospray ionization analyses.

  16. Very metal-poor galaxies: ionized gas kinematics in nine objects

    NASA Astrophysics Data System (ADS)

    Moiseev, A. V.; Pustilnik, S. A.; Kniazev, A. Y.

    2010-07-01

    The study of ionized gas morphology and kinematics in nine extremely metal-deficient (XMD) galaxies with the scanning Fabry-Perot interferometer on the Special Astrophysical Observatory (SAO) 6-m telescope is presented. Some of these very rare objects (with currently known range of O/H of 7.12 < 12 + log(O/H) < 7.65, or ) are believed to be the best proxies of `young' low-mass galaxies in the high-redshift Universe. One of the main goals of this study is to look for possible evidence of star formation (SF) activity induced by external perturbations. Recent results from HI mapping of a small subsample of XMD star-forming galaxies provided confident evidence for the important role of interaction-induced SF. Our observations provide complementary or new information that the great majority of the studied XMD dwarfs have strongly disturbed gas morphology and kinematics or the presence of detached components. We approximate the observed velocity fields by simple models of a rotating tilted thin disc, which allows us the robust detection of non-circular gas motions. These data, in turn, indicate the important role of current/recent interactions and mergers in the observed enhanced SF. As a by-product of our observations, we obtained data for two Low Surface Brightness (LSB) dwarf galaxies: Anon J012544+075957 that is a companion of the merger system UGC 993, and SAO 0822+3545 which shows off-centre, asymmetric, low star formation rate star-forming regions, likely induced by the interaction with the companion XMD dwarf HS 0822+3542. Based on observations obtained with the Special Astrophysical Observatory RAS 6-m telescope. E-mail: moisav@gmail.com (AVM); sap@sao.ru (SAP); akniazev@saao.ac.za (AYK)

  17. High pressure synthesis gas fermentation

    SciTech Connect

    Not Available

    1991-01-01

    Construction of the high pressure gas phase fermentation system is nearing completion. All non-explosion proof components will be housed separately in a gas-monitored plexiglas cabinet. A gas-monitoring system has been designed to ensure the safety of the operations in case of small or large accidental gas releases. Preliminary experiments investigating the effects of high pressure on Clostridium 1jungdahlii have shown that growth and CO uptake are not negatively affected and CO uptake by an increased total pressure of 100 psig at a syngas partial pressure of 10 psig.

  18. Qualitative Gas Chromatography-Mass Spectrometry Analyses Using Amines as Chemical Ionization Reagent Gases

    NASA Astrophysics Data System (ADS)

    Little, James L.; Howard, Adam S.

    2013-12-01

    Ammonia is a very useful chemical ionization (CI) reagent gas for the qualitative analyses of compounds by positive ion gas chromatography-mass spectrometry (GCMS). The gas is readily available, inexpensive, and leaves no carbon contamination in the MS source. Compounds of interest to our laboratory typically yield abundant protonated or ammoniated species, which are indicative of a compound's molecular weight. Nevertheless, some labile compounds fragment extensively by substitution and elimination reactions and yield no molecular weight information. In these cases, a CI reagent gas mixture of methylamine in methane prepared dynamically was found to be very useful in obtaining molecular weight data. Likewise, deuterated ammonia and deuterated methylamine are useful CI reagent gases for determining the exchangeable protons in organic compounds. Deuterated methylamine CI reagent gas is conveniently prepared by dynamically mixing small amounts of methylamine with excess deuterated ammonia.

  19. STS-39 Critical Ionization Velocity (CIV) gas release from OV-103 payload bay

    NASA Technical Reports Server (NTRS)

    1991-01-01

    A plume of nitrous oxide gas is released from a compressed gas canister mounted on the increased capacity adaptive payload carrier 1 (ICAPC-1) on the forward port side of Discovery's, Orbiter Vehicle (OV) 103's, payload bay (PLB). The gas release is part of the Critical Ionization Velocity (CIV) experiment conducted during STS-39. The Shuttle Pallet Satellite II (SPAS-II) 'parked' about two kilometers (km) away, is taking infrared, visible, and ultraviolet radiometric spatial, spectral, and temporal measurements of the gas plumes. Surrounding the CIV ICAPC-1 are: the ICAPC-2 payload support subsystem, radiometer, and Langmuir probe also mounted on the port side; the Space Test Payload 1 (STP-1) multipurpose experiment support structure (MPESS) (just beyond gas beam); and the Air Force Program 675 (AFP-675) experiment support structure (ESS).

  20. STS-39 Critical Ionization Velocity (CIV) gas release from OV-103 payload bay

    NASA Technical Reports Server (NTRS)

    1991-01-01

    A plume of nitrous oxide gas is released from a compressed gas canister mounted on the increased capacity adaptive payload carrier 1 (ICAPC-1) on the forward port side of Discovery's, Orbiter Vehicle (OV) 103's, payload bay (PLB). The gas release is part of the Critical Ionization Velocity (CIV) experiment conducted during STS-39. The Shuttle Pallet Satellite II (SPAS-II) 'parked' about two kilometers (km) away, is taking infrared, visible, and ultraviolet radiometric spatial, spectral, and temporal measurements of the gas plumes. Surrounding the CIV ICAPC-1 are: the ICAPC-2 payload support subsystem, radiometer, and Langmuir probe also mounted on the port side; the Space Test Payload 1 (STP-1) multipurpose experiment support structure (MPESS) (just beyond gas beam); and the Air Force Program 675 (AFP-675) experiment support structure (ESS).

  1. Saturation region of helium ionization detector for gas-solid and gas-liquid chromatography

    SciTech Connect

    Andrawes, F.F.; Brazell, R.S.; Gibson, E.K.

    1980-05-01

    In the saturation region of the helium detector field intensity, the detector response is independent of the electrical field. In this region (at applied potential between 200 to 2000 volts per centimeter of electrode surface) the detector is operated at a low background current, and a low noise level, but it still exhibits a stable and sensitive response. The detector in this region can be operated with high purity grade helium without any further elaborate purification processes to yield a positive response to all compounds and gases tested. The operation of the detector in this mode has been adapted to both gas-solid and gas-liquid chromatography, with temperature programming. A sample can be introduced to the column via a gas sampling injection valve or via a syringe by direct injection into a modified injection port. The detector response is linear over a range of 10/sup 6/ units with a detection limit in the picogram range for organic compounds. 11 figures.

  2. Synthesis of refractory organic matter in the ionized gas phase of the solar nebula

    PubMed Central

    Kuga, Maïa; Marty, Bernard; Marrocchi, Yves; Tissandier, Laurent

    2015-01-01

    In the nascent solar system, primitive organic matter was a major contributor of volatile elements to planetary bodies, and could have played a key role in the development of the biosphere. However, the origin of primitive organics is poorly understood. Most scenarios advocate cold synthesis in the interstellar medium or in the outer solar system. Here, we report the synthesis of solid organics under ionizing conditions in a plasma setup from gas mixtures (H2(O)−CO−N2−noble gases) reminiscent of the protosolar nebula composition. Ionization of the gas phase was achieved at temperatures up to 1,000 K. Synthesized solid compounds share chemical and structural features with chondritic organics, and noble gases trapped during the experiments reproduce the elemental and isotopic fractionations observed in primitive organics. These results strongly suggest that both the formation of chondritic refractory organics and the trapping of noble gases took place simultaneously in the ionized areas of the protoplanetary disk, via photon- and/or electron-driven reactions and processing. Thus, synthesis of primitive organics might not have required a cold environment and could have occurred anywhere the disk is ionized, including in its warm regions. This scenario also supports N2 photodissociation as the cause of the large nitrogen isotopic range in the solar system. PMID:26039983

  3. Synthesis of refractory organic matter in the ionized gas phase of the solar nebula.

    PubMed

    Kuga, Maïa; Marty, Bernard; Marrocchi, Yves; Tissandier, Laurent

    2015-06-09

    In the nascent solar system, primitive organic matter was a major contributor of volatile elements to planetary bodies, and could have played a key role in the development of the biosphere. However, the origin of primitive organics is poorly understood. Most scenarios advocate cold synthesis in the interstellar medium or in the outer solar system. Here, we report the synthesis of solid organics under ionizing conditions in a plasma setup from gas mixtures (H2(O)-CO-N2-noble gases) reminiscent of the protosolar nebula composition. Ionization of the gas phase was achieved at temperatures up to 1,000 K. Synthesized solid compounds share chemical and structural features with chondritic organics, and noble gases trapped during the experiments reproduce the elemental and isotopic fractionations observed in primitive organics. These results strongly suggest that both the formation of chondritic refractory organics and the trapping of noble gases took place simultaneously in the ionized areas of the protoplanetary disk, via photon- and/or electron-driven reactions and processing. Thus, synthesis of primitive organics might not have required a cold environment and could have occurred anywhere the disk is ionized, including in its warm regions. This scenario also supports N2 photodissociation as the cause of the large nitrogen isotopic range in the solar system.

  4. Ultralow-voltage field-ionization discharge on whiskered silicon nanowires for gas-sensing applications.

    PubMed

    Banan Sadeghian, Ramin; Islam, M Saif; Saif Islam, M

    2011-02-01

    Several hundred million volts per centimetre of electric-field strength are required to field-ionize gas species. Such fields are produced on sharp metallic tips under a bias of a few kilovolts. Here, we show that field ionization is possible at dramatically lower fields on semiconductor nanomaterials containing surface states, particularly with metal-catalysed whiskers grown on silicon nanowires. The low-voltage field-ionization phenomena observed here cannot be explained solely on the basis of the large field-amplification effect of suspended gold nanoparticles present on the whisker tips. We postulate that field penetration causes upward band-bending at the surface of exposed silicon containing surface states in the vicinity of the catalyst. Band-bending enables the valence electron to tunnel into the surface states at reduced fields. This work provides a basis for development of low-voltage ionization sensors. Although demonstrated on silicon, low-voltage field ionization can be detected on any sharp semiconductor tip containing proper surface states.

  5. Studies of Flow in Ionized Gas: Historical Perspective, Contemporary Experiments, and Applications

    SciTech Connect

    Popovic, S.; Vuskovic, L.

    2007-04-23

    Since the first observations that a very small ionized fraction (order of 1 ppm) could strongly affect the gas flow, numerous experiments with partially or fully wall-free discharges have demonstrated the dispersion of shock waves, the enhancement of lateral forces in the flow, the prospects of levitation, and other aerodynamic effects with vast potential of application. A review of physical effects and observations are given along with current status of their interpretation. Special attention will be given to the physical problems of energy efficiency in generating wall-free discharges and the phenomenology of filamentary discharges. Comments and case examples are given on the current status of availability of necessary data for modelling and simulation of the aerodynamic phenomena in weakly ionized gas.

  6. Inner polar ionized-gas disks and properties of their host galaxies

    NASA Astrophysics Data System (ADS)

    Sil'chenko, Olga K.

    2015-02-01

    I have analyzed line-of-sight velocity fields of the stellar and ionized-gas components for the volume-limited sample of nearby lenticular galaxies by using the raw data of the ATLAS-3D survey undertaken with the integral-field spectrograph SAURON. Among 200 nearby lenticular galaxies, I distinguish 20 cases of nearly orthogonal rotation of the inner ionized gas with respect to the central stellar components; so I estimate a frequency of the inner polar disks in nearby S0 galaxies as 10%. Properties of the central stellar populations - mean ages, metallicities, magnesium-to-iron ratios - are derived through the Lick indices. The typical stellar population properties of the polar-disk host galaxies are exactly the same as the stellar population properties of the complete sample.

  7. Photon-echo studies of collisional relaxation in weakly ionized noble-gas mixtures.

    PubMed

    Woodworth, M R

    1983-06-01

    Photon-echo relaxation rates are measured in weakly ionized plasmas of binary mixtures of noble gases, in which the photon echo generated on a transition in one noble-gas species is damped primarily by atoms of the second species. The special cases of pure krypton and xenon are extensions of previous work in pure helium, neon, and argon. With the exception of mixtures with helium as the perturber, measured relaxation rates are consistent with collisional line-broadening calculations.

  8. FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): Pulse Operation of Chemical Oxygen-Iodine Laser by Pulsed Gas Discharge with the Assistance of Spark Pre-ionization

    NASA Astrophysics Data System (ADS)

    Li, Guo-Fu; Yu, Hai-Jun; Duo, Li-Ping; Jin, Yu-Qi; Wang, Jian; Sang, Feng-Ting; Fang, Ben-Jie; Wang, De-Zhen

    2009-11-01

    The continuous wavelength chemical oxygen-iodine laser can be turned into pulse operation mode in order to obtain high energy and high pulse power. We propose an approach to produce iodine atoms instantaneously by pulsed gas discharge with the assistance of spark pre-ionization to achieve the pulsed goal. The influence of spark pre-ionization on discharge homogeneity is discussed. Voltage-current characteristics are shown and discussed in existence of the pre-ionization capacitor and peaking capacitor. The spark pre-ionization and peaking capacitor are very helpful in obtaining a stable and homogeneous discharge. The lasing is achieved at the total pressure of 2.2-2.9kPa and single pulse energy is up to 180 mJ, the corresponding specific output energy is 1.0 J/L.

  9. Al III, Si IV, and C IV absorption toward zeta Ophiuchi: Evidence for photionized and collisionally ionized gas

    NASA Technical Reports Server (NTRS)

    Sembach, Kenneth R.; Savage, Blair D.; Jenkins, Edward B.

    1994-01-01

    We present Goddard High-Resolution Spectrograph observations at 3.5 km/s resolution and signal-to-noise ratios of 30 to 60 for the Al III, Si IV, and N V absorption lines in the far-ultraviolet spectrum of the O9.5 V star zeat Ophiuchi. The measurement reveal three types of highly ionized gas along the 140 pc line of sight. (1) Narrow components of Al III (b = 4.3 km/s, the mean value of (v(helio)) = -7.8 km/s; b = 3.2 km/s, the mean value of (v(sub helio)) = -14.4 km/s) and Si IV (b = 5.3 km/s, the mean value of (v(sub helio)) = -15.0 km/s) trace photionized gas in the expanding H II region surrounding zeta Oph. The observed magnitude and direction of the velocity offset between the Al III and Si IV profiles can be explained by models of H II regions that incorporate expansion. Narrow C IV absorption associated with the H II region is not detected. Predictions of the expected amounts of Si IV and C IV overestimate the column densities of these ions by factors of 30 and more than 10, respectively. The discrepancy may be due to the effects of elemental depletions in the gas and/or to the interaction of the stellar wind with surrounding matter. (2) Broad (b = 15 to 18 km/s) and weak Si IV and C IV absorption components are detected near the mean value of (v(sub helio)) = -26 km/s. The high-ionization species associated with these absorption components are probably produced by electron collisional ionization in a heated gas. This absorption may be physically related to the zeta Oph bow shock ot to a cloud complex situated within the local interstellar medium at d less than 60 pc. The C IV to Si IV column density ratio in this gas is 8, a factor of 6 less than conductive interface models predict, but this discrepancy may be removed by considering the effects of self-photoionization within the cooling gas in the model calculations. (3) A broad (b = 13 km/s) and weak C IV absorption feature detected at the mean value of (v(sub helio)) = -61 km/s is not seen in other

  10. High gas flow alpha detector

    DOEpatents

    Bolton, R.D.; Bounds, J.A.; Rawool-Sullivan, M.W.

    1996-05-07

    An alpha detector for application in areas of high velocity gas flows, such as smokestacks and air vents. A plurality of spaced apart signal collectors are placed inside an enclosure, which would include smokestacks and air vents, in sufficient numbers to substantially span said enclosure so that gas ions generated within the gas flow are electrostatically captured by the signal collector means. Electrometer means and a voltage source are connected to the signal collectors to generate an electrical field between adjacent signal collectors, and to indicate a current produced through collection of the gas ions by the signal collectors. 4 figs.

  11. High gas flow alpha detector

    DOEpatents

    Bolton, Richard D.; Bounds, John A.; Rawool-Sullivan, Mohini W.

    1996-01-01

    An alpha detector for application in areas of high velocity gas flows, such as smokestacks and air vents. A plurality of spaced apart signal collectors are placed inside an enclosure, which would include smokestacks and air vents, in sufficient numbers to substantially span said enclosure so that gas ions generated within the gas flow are electrostatically captured by the signal collector means. Electrometer means and a voltage source are connected to the signal collectors to generate an electrical field between adjacent signal collectors, and to indicate a current produced through collection of the gas ions by the signal collectors.

  12. Drifting localization of ionization runaway: Unraveling the nature of anomalous transport in high power impulse magnetron sputtering

    SciTech Connect

    Anders, Andre; Ni, Pavel; Rauch, Albert

    2012-03-01

    The plasma over a magnetron's erosion ''racetrack'' is not azimuthally uniform but concentrated in distinct dense ionization zones which move in the ExB direction with about 10% of the electron ExB/B{sup 2} drift velocity. The ionization zones are investigated with a gated camera working in concert with a streak camera for Al, Nb, Cu, and W targets in Ar or Kr background gas. It is found that each ionization zone has a high plasma density edge, which is the origin of a plasma-generating electron jet leaving the target zone. Each region of strong azimuthal plasma density gradient generates an azimuthal electric field, which promotes the escape of magnetized electrons and the formation of electron jets and plasma flares. The phenomena are proposed to be caused by an ionization instability where each dense plasma zone exhibits a high stopping power for drifting high energy electrons, thereby enhancing itself.

  13. The Vertical Structure of Diffuse Ionized Gas in Galactic Spiral Arms

    NASA Astrophysics Data System (ADS)

    Krishnarao, Dhanesh; Haffner, L. Matthew; Benjamin, Robert A.

    2017-01-01

    The Wisconsin H-Alpha Mapper provides the most sensitive velocity resolved observations of diffuse Hα, [S II] λ6716, and [N II] λ6584 emission in the Galaxy, tracing the warm (~8000K) ionized component of the interstellar medium. The vertical extent of this diffuse gas can directly impact the midplane pressure, influencing cold molecular clouds and star formation in the disk. Here, we analyze the vertical structure of the warm ionized medium around multiple spiral arm components of the Galaxy. Diffuse halo emission is isolated using longitude varying velocity channels guided by CO emission tracing cold molecular gas in the disk. We find exponential electron density squared (or emission measure) scale heights and analyze its behavior as a function of Galactocentric radius and the presence of cold molecular clouds and star forming regions in the disk. Statistical analysis of the behavior of [S II]/Hα and [N II]/Hα line ratios along some of these spiral arms disentangle the complex physical conditions of the warm ionized gas as a function of height and in-situ electron density. Some spiral arm sections, in particular the far Carina arm, have significantly larger (>3x) scale heights than previously studied arms that tend to increase as a function of Galactocentric radius.

  14. Breakdown voltage reduction by field emission in multi-walled carbon nanotubes based ionization gas sensor

    SciTech Connect

    Saheed, M. Shuaib M.; Muti Mohamed, Norani; Arif Burhanudin, Zainal

    2014-03-24

    Ionization gas sensors using vertically aligned multi-wall carbon nanotubes (MWCNT) are demonstrated. The sharp tips of the nanotubes generate large non-uniform electric fields at relatively low applied voltage. The enhancement of the electric field results in field emission of electrons that dominates the breakdown mechanism in gas sensor with gap spacing below 14 μm. More than 90% reduction in breakdown voltage is observed for sensors with MWCNT and 7 μm gap spacing. Transition of breakdown mechanism, dominated by avalanche electrons to field emission electrons, as decreasing gap spacing is also observed and discussed.

  15. Fluctuations in microwave background radiation due to secondary ionization of the intergalactic gas in the universe

    NASA Technical Reports Server (NTRS)

    Sunyayev, R. A.

    1979-01-01

    Secondary heating and ionization of the intergalactic gas at redshifts z approximately 10-30 could lead to the large optical depth of the Universe for Thomson scattering and could smooth the primordial fluctuations formed at z approximately 1500. It is shown that the gas motions connected with the large scale density perturbations at z approximately 10-15 must lead to the generation of secondary fluctuations of microwave background. The contribution of the rich clusters of galaxies and young galaxies to the fluctuations of microwave background is also estimated.

  16. Ionized gas dynamics in the inner 2 pc of Sgr A West

    NASA Astrophysics Data System (ADS)

    Lacy, John H.; Irons, Wesley T.; Richter, Matthew J.

    2014-05-01

    We present a data cube of the [NeII] (12.8 μm) emission from the inner 2 pc of Sgr A West with 1″ and 4 km s-1 resolution, and with substantially better SNR and velocity resolution than previous observations of the ionized gas. We compare the observations to two proposed models of the gas motions and distribution: flows along tidally stretched streamers, and more nearly circular motions with density wave compression. The density wave model provides a considerably better fit to the kinematics of the northern arm and western arc. Neither model fits the eastern arm and bar kinematics well.

  17. Ionization of Local Interstellar Gas Based on STIS and FUSE spectra of Nearby Stars

    NASA Astrophysics Data System (ADS)

    Redfield, Seth; Linsky, J. L.

    2009-01-01

    The ultraviolet contains many resonance line transitions that are sensitive to a range of ionization stages of ions present in the local interstellar medium (LISM). We couple observations of high resolution ultraviolet spectrographs, STIS and GHRS on the Hubble Space Telescope (HST) and the Far-Ultraviolet Spectroscopic Explorer (FUSE) in order to make a comprehensive survey of the ionization structure of the local interstellar medium. In particular, we focus on the sight line toward G191-B2B, a nearby (69 pc) white dwarf. We present interstellar detections of highly ionized elements (e.g., SiIII, CIII, CIV, etc) and compare them directly to neutral or singly ionized LISM detections (e.g., SiII, CII, etc). The extensive observations of G191-B2B provides an opportunity for a broad study of ionization stages of several elements, while a survey of several sight lines provides a comprehensive look at the ionization structure of the LISM. We acknowledge support for this project through NASA FUSE Grant NNX06AD33G.

  18. Nuclear signal simulation applied to gas ionizing chambers

    SciTech Connect

    Coulon, Romain; Dumazert, Jonathan

    2015-07-01

    Particle transport codes used in detector simulation allow the calculation of the energy deposited by charged particles produced following an interaction. The pulses temporal shaping is more and more used in nuclear measurement into pulse shape analysis techniques. A model is proposed in this paper to simulate the pulse temporal shaping and the associated noise level thanks to the output track file PTRAC provides by Monte-Carlo particle transport codes. The model has been dedicated to ion chambers and more especially for High Pressure Xenon chambers HPXe where the pulse shape analysis can resolve some issues regarding with this technology as the ballistic deficit phenomenon. The model is fully described and an example is presented as a validation of such full detector simulation. (authors)

  19. Escape fraction of ionizing photons from high-redshift galaxies in cosmological SPH simulations

    NASA Astrophysics Data System (ADS)

    Yajima, Hidenobu; Choi, Jun-Hwan; Nagamine, Kentaro

    2011-03-01

    Combing the three-dimensional radiative transfer (RT) calculation and cosmological smoothed particle hydrodynamics (SPH) simulations, we study the escape fraction of ionizing photons (fesc) of high-redshift galaxies at z= 3-6. Our simulations cover the halo mass range of Mh= 109-1012 M⊙. We post-process several hundred simulated galaxies with the Authentic Radiative Transfer (ART) code to study the halo mass dependence of fesc. In this paper, we restrict ourselves to the transfer of stellar radiation from local stellar population in each dark matter halo. We find that the average fesc steeply decreases as the halo mass increases, with a large scatter for the lower-mass haloes. The low-mass haloes with Mh˜ 109 M⊙ have large values of fesc (with an average of ˜0.4), whereas the massive haloes with Mh˜ 1011 M⊙ show small values of fesc (with an average of ˜0.07). This is because in our simulations, the massive haloes show more clumpy structure in gas distribution, and the star-forming regions are embedded inside these clumps, making it more difficult for the ionizing photons to escape. On the other hand, in low-mass haloes, there are often conical regions of highly ionized gas due to the shifted location of young star clusters from the centre of dark matter halo, which allows the ionizing photons to escape more easily than in the high-mass haloes. By counting the number of escaped ionizing photons, we show that the star-forming galaxies can ionize the intergalactic medium at z= 3-6. The main contributor to the ionizing photons is the haloes with Mh≲ 1010 M⊙ owing to their high fesc. The large dispersion in fesc suggests that there may be various sizes of H II bubbles around the haloes even with the same mass in the early stages of reionization. We also examine the effect of UV background radiation field on fesc using simple, four different treatments of UV background.

  20. H-alpha LEGUS: Unveiling the Interplay Between Stars, Star Clusters, and Ionized Gas

    NASA Astrophysics Data System (ADS)

    Chandar, Rupali

    2014-10-01

    We propose to obtain narrow-band, H-alpha observations for a significant subset of the star-forming, nearby galaxies recently targeted by the LEGUS treasury program (GO-13364). LEGUS is observing these galaxies in five broad-band filters: NUV, U, B, V, and I. The new H-alpha observations will reveal thousands of previously undetected HII regions, including those ionized by stellar clusters and single massive stars, allow us to measure their luminosities and sizes, and to separate discrete sources from diffuse ionized gas. We will use our narrow-band imaging survey to: (1) establish the connection between star and cluster formation, and determine the prevelance with which isolated massive stars form in different galaxies; (2) determine whether the initial cluster mass function is universal; (3) investigate the size evolution of ionized gas bubbles, and how this depends on cluster age and mass, as well as on local galactic conditions; and (4) place stringent limits on the leakage of ionizing photons from HII regions, and better understand how the interplay between properties of the ionizing source and the morphology of the HII region impacts leakage. The broad goal of this study is to better understand how feedback from massive stars affects the surrounding medium. Ultimately, the interplay between feedback and the ISM on these scales will enable a better understanding of galaxy-scale outflows in the early universe, a process critical to galaxy evolution. This program naturally lends itself to an improvement of the scientific output by involving the general public via an already established Citizen Science program.

  1. Improved gas chromatography-flame ionization detector analytical method for the analysis of epoxy fatty acids.

    PubMed

    Mubiru, Edward; Shrestha, Kshitij; Papastergiadis, Antonios; De Meulenaer, Bruno

    2013-11-29

    In this study an improved method for analysis of epoxy fatty acids is reported. Data obtained from analysis of polar fatty acids has previously been presented, but due to the high number of compounds that co-elute in the polar fraction, the resultant chromatograms are complex which may lead to compromising the accuracy of the data. A three steps separation of fatty acid methyl esters (FAMEs) by solid-phase extraction (SPE) on a silica gel column to remove hydroxy fatty acid interferences was proposed. This approach is opposed to a two step separation procedure that has been often used to prevent analytical interferences caused by non-altered fatty acids. A gas chromatograph with a flame ionization detector (GC-FID) equipped with a polar CP-Sil 88™ column was used. Quantification was based on the use of methyl nonadecanoate (C19:0), as an internal standard. Individual mono epoxy fatty acids were well separated without co-eluting compounds. The optimized method was finally applied to screen epoxy fatty acids in 37 fresh oil samples. Results obtained for the total epoxy fatty acids were in the range 0.03-2mgg(-1) of oil with repeatability coefficient of variation (CV) ranging from 2.8 to 9.9% for duplicate analysis showing that the results obtained are repeatable.

  2. High pressure synthesis gas fermentation

    SciTech Connect

    Not Available

    1992-01-01

    The construction of the high pressure gas phase fermentation system has been completed. Photographs of the various components of the system are presented, along with an operating procedure for the equipment.

  3. DETERMINATION OF PHTHALATES IN WATER AND SOIL BY TANDEM MASS SPECTROMETRY UNDER CHEMICAL IONIZATION CONDITIONS WITH ISOBUTANE AS REAGENT GAS

    EPA Science Inventory

    Phthalate determination is important because phthalates often are major impurities in samples and can have significant health effects. Tandem mass spectrometry under chemical ionization mass spectrometry conditions with isobutane as the reagent gas was used to determine 11 phthal...

  4. INTEGRAL-FIELD STELLAR AND IONIZED GAS KINEMATICS OF PECULIAR VIRGO CLUSTER SPIRAL GALAXIES

    SciTech Connect

    Cortés, Juan R.; Hardy, Eduardo; Kenney, Jeffrey D. P. E-mail: ehardy@nrao.cl

    2015-01-01

    We present the stellar and ionized gas kinematics of 13 bright peculiar Virgo cluster galaxies observed with the DensePak Integral Field Unit at the WIYN 3.5 m telescope in order to look for kinematic evidence that these galaxies have experienced gravitational interactions or gas stripping. Two-dimensional maps of the stellar velocity V, stellar velocity dispersion σ, and the ionized gas velocity (Hβ and/or [O III]) are presented for the galaxies in the sample. The stellar rotation curves and velocity dispersion profiles are determined for 13 galaxies, and the ionized gas rotation curves are determined for 6 galaxies. Misalignments between the optical and kinematical major axes are found in several galaxies. While in some cases this is due to a bar, in other cases it seems to be associated with gravitational interaction or ongoing ram pressure stripping. Non-circular gas motions are found in nine galaxies, with various causes including bars, nuclear outflows, or gravitational disturbances. Several galaxies have signatures of kinematically distinct stellar components, which are likely signatures of accretion or mergers. For all of our galaxies, we compute the angular momentum parameter λ {sub R}. An evaluation of the galaxies in the λ {sub R} ellipticity plane shows that all but two of the galaxies have significant support from random stellar motions, and have likely experienced gravitational interactions. This includes some galaxies with very small bulges and truncated/compact Hα morphologies, indicating that such galaxies cannot be fully explained by simple ram pressure stripping, but must have had significant gravitational encounters. Most of the sample galaxies show evidence for ICM-ISM stripping as well as gravitational interactions, indicating that the evolution of a significant fraction of cluster galaxies is likely strongly impacted by both effects.

  5. Photoionization and High Density Gas

    NASA Technical Reports Server (NTRS)

    Kallman, T.; Bautista, M.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present results of calculations using the XSTAR version 2 computer code. This code is loosely based on the XSTAR v.1 code which has been available for public use for some time. However it represents an improvement and update in several major respects, including atomic data, code structure, user interface, and improved physical description of ionization/excitation. In particular, it now is applicable to high density situations in which significant excited atomic level populations are likely to occur. We describe the computational techniques and assumptions, and present sample runs with particular emphasis on high density situations.

  6. Ion energies in high power impulse magnetron sputtering with and without localized ionization zones

    SciTech Connect

    Yang, Yuchen; Tanaka, Koichi; Liu, Jason; Anders, André

    2015-03-23

    High speed imaging of high power impulse magnetron sputtering discharges has revealed that ionization is localized in moving ionization zones but localization disappears at high currents for high yield targets. This offers an opportunity to study the effect ionization zones have on ion energies. We measure that ions have generally higher energies when ionization zones are present, supporting the concept that these zones are associated with moving potential humps. We propose that the disappearance of ionization zones is caused by an increased supply of atoms from the target which cools electrons and reduces depletion of atoms to be ionized.

  7. Resonancelike enhancement in high-order above-threshold ionization of molecules

    NASA Astrophysics Data System (ADS)

    Quan, Wei; Lai, XuanYang; Chen, YongJu; Wang, ChuanLiang; Hu, ZiLong; Liu, XiaoJun; Hao, XiaoLei; Chen, Jing; Hasović, Elvedin; Busuladžić, Mustafa; Becker, Wilhelm; Milošević, Dejan B.

    2013-08-01

    Rresonancelike enhancement of groups of adjacent peaks in the photoelectron spectrum of high-order above-threshold ionization has been well documented for noble-gas atoms subjected to intense infrared laser pulses. However, its physical origin is still under debate. In this Rapid Communication, we investigate experimentally and theoretically high-order above-threshold ionization of diatomic nitrogen and oxygen molecules in order to shed more light on the underlying mechanism. The resonancelike enhancement is experimentally observed for N2 but is absent for O2 molecules. A simulation on the basis of S-matrix theory and the strong-field approximation reproduces the experimental observations. This implies that the resonancelike enhancement can be attributed to the channel-closing effect. The specific molecular structure plays a decisive role for the presence or absence of this enhancement in molecular systems.

  8. Compact ultrafast orthogonal acceleration time-of-flight mass spectrometer for on-line gas analysis by electron impact ionization and soft single photon ionization using an electron beam pumped rare gas excimer lamp as VUV-light source.

    PubMed

    Mühlberger, F; Saraji-Bozorgzad, M; Gonin, M; Fuhrer, K; Zimmermann, R

    2007-11-01

    Orthogonal acceleration time-of-flight mass spectrometers (oaTOFMS), which are exhibiting a pulsed orthogonal extraction of ion bunches into the TOF mass analyzer from a continuous primary ion beam, are well-suited for continuous ionization methods such as electron impact ionization (EI). Recently an electron beam pumped rare gas excimer lamp (EBEL) was introduced, which emits intensive vacuum UV (VUV) radiation at, e.g., 126 nm (argon excimer) and is well suited as the light source for soft single photon ionization (SPI) of organic molecules. In this paper, a new compact oaTOFMS system which allows switching between SPI, using VUV-light from an EBEL-light source, and conventional EI is described. With the oaTOFMS system, EBEL-SPI and EI mass spectral transients can be recorded at very high repetition rates (up to 100 kHz), enabling high duty cycles and therefore good detection efficiencies. By using a transient recorder card with the capability to perform on-board accumulation of the oaTOF transients, final mass spectra with a dynamic range of 106 can be saved to the hard disk at a rate of 10 Hz. As it is possible to change the ionization modes (EI and SPI) rapidly, a comprehensive monitoring of complex gases with highly dynamic compositions, such as cigarette smoke, is possible. In this context, the EI based mass spectra address the bulk composition (compounds such as water, oxygen, carbon dioxide, etc. in the up to percentage concentration range) as well as some inorganic trace gases such as argon, sulfur dioxide, etc. down to the low ppm level. The EBEL-SPI mass spectra on the other hand are revealing the organic composition down to the lower ppb concentration range.

  9. A novel benzene quantitative analysis method using miniaturized metal ionization gas sensor and non-linear bistable dynamic system

    PubMed Central

    Tang, Xuxiang; Liu, Fuqi

    2015-01-01

    In this paper, a novel benzene quantitative analysis method utilizing miniaturized metal ionization gas sensor and non-linear bistable dynamic system was investigated. Al plate anodic gas-ionization sensor was installed for electrical current-voltage data measurement. Measurement data was analyzed by non-linear bistable dynamics system. Results demonstrated that this method realized benzene concentration quantitative determination. This method is promising in laboratory safety management in benzene leak detection. PMID:26218927

  10. A novel benzene quantitative analysis method using miniaturized metal ionization gas sensor and non-linear bistable dynamic system.

    PubMed

    Tang, Xuxiang; Liu, Fuqi

    2015-01-01

    In this paper, a novel benzene quantitative analysis method utilizing miniaturized metal ionization gas sensor and non-linear bistable dynamic system was investigated. Al plate anodic gas-ionization sensor was installed for electrical current-voltage data measurement. Measurement data was analyzed by non-linear bistable dynamics system. Results demonstrated that this method realized benzene concentration quantitative determination. This method is promising in laboratory safety management in benzene leak detection.

  11. High-energy ionization by relativistically intense laser pulses

    NASA Astrophysics Data System (ADS)

    Kamiński, J. Z.; Cajiao Vélez, F.; Krajewska, K.

    2017-07-01

    High-energy ionization by relativistically intense, 30~\\text{fs} laser pulses is investigated within the relativistic strong-field approximation. It is shown that the momentum distribution of photoelectrons is focused around a spiral, the analytical form of which is derived from the saddle-point analysis of probability amplitudes. The geometry of this spiral allows one to clearly interpret the exact numerical results of the ionization probability distributions and to identify the photoelectron momentum domains in which the interference- and the interference-free patterns are observed. It is also demonstrated that attosecond single-electron wave packets can be created in this process. Thus, it opens new research opportunities for the four-dimensional electron diffraction experiments, which can be conducted in large-scale laser facilities such as ELI or XCELS.

  12. High-resolution ionization detector and array of such detectors

    DOEpatents

    McGregor, Douglas S.; Rojeski, Ronald A.

    2001-01-16

    A high-resolution ionization detector and an array of such detectors are described which utilize a reference pattern of conductive or semiconductive material to form interaction, pervious and measurement regions in an ionization substrate of, for example, CdZnTe material. The ionization detector is a room temperature semiconductor radiation detector. Various geometries of such a detector and an array of such detectors produce room temperature operated gamma ray spectrometers with relatively high resolution. For example, a 1 cm.sup.3 detector is capable of measuring .sup.137 Cs 662 keV gamma rays with room temperature energy resolution approaching 2% at FWHM. Two major types of such detectors include a parallel strip semiconductor Frisch grid detector and the geometrically weighted trapezoid prism semiconductor Frisch grid detector. The geometrically weighted detector records room temperature (24.degree. C.) energy resolutions of 2.68% FWHM for .sup.137 Cs 662 keV gamma rays and 2.45% FWHM for .sup.60 Co 1.332 MeV gamma rays. The detectors perform well without any electronic pulse rejection, correction or compensation techniques. The devices operate at room temperature with simple commercially available NIM bin electronics and do not require special preamplifiers or cooling stages for good spectroscopic results.

  13. Radical Generation from the Gas-Phase Activation of Ionized Lipid Ozonides

    NASA Astrophysics Data System (ADS)

    Ellis, Shane R.; Pham, Huong T.; in het Panhuis, Marc; Trevitt, Adam J.; Mitchell, Todd W.; Blanksby, Stephen J.

    2017-07-01

    Reaction products from the ozonolysis of unsaturated lipids at gas-liquid interfaces have the potential to significantly influence the chemical and physical properties of organic aerosols in the atmosphere. In this study, the gas-phase dissociation behavior of lipid secondary ozonides is investigated using ion-trap mass spectrometry. Secondary ozonides were formed by reaction between a thin film of unsaturated lipids (fatty acid methyl esters or phospholipids) with ozone before being transferred to the gas phase as [M + Na]+ ions by electrospray ionization. Activation of the ionized ozonides was performed by either energetic collisions with helium buffer-gas or laser photolysis, with both processes yielding similar product distributions. Products arising from the decomposition of the ozonides were characterized by their mass-to-charge ratio and subsequent ion-molecule reactions. Product assignments were rationalized as arising from initial homolysis of the ozonide oxygen-oxygen bond with subsequent decomposition of the nascent biradical intermediate. In addition to classic aldehyde and carbonyl oxide-type fragments, carbon-centered radicals were identified with a number of decomposition pathways that indicated facile unimolecular radical migration. These findings reveal that photoactivation of secondary ozonides formed by the reaction of aerosol-bound lipids with tropospheric ozone may initiate radical-mediated chemistry within the particle resulting in surface modification.

  14. Radical Generation from the Gas-Phase Activation of Ionized Lipid Ozonides.

    PubMed

    Ellis, Shane R; Pham, Huong T; In Het Panhuis, Marc; Trevitt, Adam J; Mitchell, Todd W; Blanksby, Stephen J

    2017-07-01

    Reaction products from the ozonolysis of unsaturated lipids at gas-liquid interfaces have the potential to significantly influence the chemical and physical properties of organic aerosols in the atmosphere. In this study, the gas-phase dissociation behavior of lipid secondary ozonides is investigated using ion-trap mass spectrometry. Secondary ozonides were formed by reaction between a thin film of unsaturated lipids (fatty acid methyl esters or phospholipids) with ozone before being transferred to the gas phase as [M + Na](+) ions by electrospray ionization. Activation of the ionized ozonides was performed by either energetic collisions with helium buffer-gas or laser photolysis, with both processes yielding similar product distributions. Products arising from the decomposition of the ozonides were characterized by their mass-to-charge ratio and subsequent ion-molecule reactions. Product assignments were rationalized as arising from initial homolysis of the ozonide oxygen-oxygen bond with subsequent decomposition of the nascent biradical intermediate. In addition to classic aldehyde and carbonyl oxide-type fragments, carbon-centered radicals were identified with a number of decomposition pathways that indicated facile unimolecular radical migration. These findings reveal that photoactivation of secondary ozonides formed by the reaction of aerosol-bound lipids with tropospheric ozone may initiate radical-mediated chemistry within the particle resulting in surface modification. Graphical Abstract ᅟ.

  15. P-MaNGA Galaxies: emission-lines properties - gas ionization and chemical abundances from prototype observations

    NASA Astrophysics Data System (ADS)

    Belfiore, F.; Maiolino, R.; Bundy, K.; Thomas, D.; Maraston, C.; Wilkinson, D.; Sánchez, S. F.; Bershady, M.; Blanc, G. A.; Bothwell, M.; Cales, S. L.; Coccato, L.; Drory, N.; Emsellem, E.; Fu, H.; Gelfand, J.; Law, D.; Masters, K.; Parejko, J.; Tremonti, C.; Wake, D.; Weijmans, A.; Yan, R.; Xiao, T.; Zhang, K.; Zheng, T.; Bizyaev, D.; Kinemuchi, K.; Oravetz, D.; Simmons, A.

    2015-05-01

    MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a 6-yr Sloan Digital Sky Survey (SDSS-IV) survey that will obtain spatially resolved spectroscopy from 3600 to 10 300 Å for a representative sample of over 10 000 nearby galaxies. In this paper, we present the analysis of nebular emission-line properties using observations of 14 galaxies obtained with P-MaNGA, a prototype of the MaNGA instrument. By using spatially resolved diagnostic diagrams, we find extended star formation in galaxies that are centrally dominated by Seyfert/LINER-like emission, which illustrates that galaxy characterizations based on single fibre spectra are necessarily incomplete. We observe extended low ionization nuclear emission-line regions (LINER)-like emission (up to 1Re) in the central regions of three galaxies. We make use of the Hα equivalent width [EW(Hα)] to argue that the observed emission is consistent with ionization from hot evolved stars. We derive stellar population indices and demonstrate a clear correlation between Dn(4000) and EW(HδA) and the position in the ionization diagnostic diagram: resolved galactic regions which are ionized by a Seyfert/LINER-like radiation field are also devoid of recent star formation and host older and/or more metal-rich stellar populations. We also detect extraplanar LINER-like emission in two highly inclined galaxies, and identify it with diffuse ionized gas. We investigate spatially resolved metallicities and find a positive correlation between metallicity and star formation rate surface density. We further study the relation between N/O versus O/H on resolved scales. We find that, at given N/O, regions within individual galaxies are spread towards lower metallicities, deviating from the sequence defined by galactic central regions as traced by Sloan 3-arcsec fibre spectra. We suggest that the observed dispersion can be a tracer for gas flows in galaxies: infalls of pristine gas and/or the effect of a galactic fountain.

  16. Ionization Processes in the Atmosphere of Titan (Research Note). III. Ionization by High-Z Nuclei Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Gronoff, G.; Mertens, C.; Lilensten, J.; Desorgher, L.; Fluckiger, E.; Velinov, P.

    2011-01-01

    Context. The Cassini-Huygens mission has revealed the importance of particle precipitation in the atmosphere of Titan thanks to in-situ measurements. These ionizing particles (electrons, protons, and cosmic rays) have a strong impact on the chemistry, hence must be modeled. Aims. We revisit our computation of ionization in the atmosphere of Titan by cosmic rays. The high-energy high-mass ions are taken into account to improve the precision of the calculation of the ion production profile. Methods. The Badhwahr and O Neill model for cosmic ray spectrum was adapted for the Titan model. We used the TransTitan model coupled with the Planetocosmics model to compute the ion production by cosmic rays. We compared the results with the NAIRAS/HZETRN ionization model used for the first time for a body that differs from the Earth. Results. The cosmic ray ionization is computed for five groups of cosmic rays, depending on their charge and mass: protons, alpha, Z = 8 (oxygen), Z = 14 (silicon), and Z = 26 (iron) nucleus. Protons and alpha particles ionize mainly at 65 km altitude, while the higher mass nucleons ionize at higher altitudes. Nevertheless, the ionization at higher altitude is insufficient to obscure the impact of Saturn s magnetosphere protons at a 500 km altitude. The ionization rate at the peak (altitude: 65 km, for all the different conditions) lies between 30 and 40/cu cm/s. Conclusions. These new computations show for the first time the importance of high Z cosmic rays on the ionization of the Titan atmosphere. The updated full ionization profile shape does not differ significantly from that found in our previous calculations (Paper I: Gronoff et al. 2009, 506, 955) but undergoes a strong increase in intensity below an altitude of 400 km, especially between 200 and 400 km altitude where alpha and heavier particles (in the cosmic ray spectrum) are responsible for 40% of the ionization. The comparison of several models of ionization and cosmic ray spectra (in

  17. Ionization Processes in the Atmosphere of Titan (Research Note). III. Ionization by High-Z Nuclei Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Gronoff, G.; Mertens, C.; Lilensten, J.; Desorgher, L.; Fluckiger, E.; Velinov, P.

    2011-01-01

    Context. The Cassini-Huygens mission has revealed the importance of particle precipitation in the atmosphere of Titan thanks to in-situ measurements. These ionizing particles (electrons, protons, and cosmic rays) have a strong impact on the chemistry, hence must be modeled. Aims. We revisit our computation of ionization in the atmosphere of Titan by cosmic rays. The high-energy high-mass ions are taken into account to improve the precision of the calculation of the ion production profile. Methods. The Badhwahr and O Neill model for cosmic ray spectrum was adapted for the Titan model. We used the TransTitan model coupled with the Planetocosmics model to compute the ion production by cosmic rays. We compared the results with the NAIRAS/HZETRN ionization model used for the first time for a body that differs from the Earth. Results. The cosmic ray ionization is computed for five groups of cosmic rays, depending on their charge and mass: protons, alpha, Z = 8 (oxygen), Z = 14 (silicon), and Z = 26 (iron) nucleus. Protons and alpha particles ionize mainly at 65 km altitude, while the higher mass nucleons ionize at higher altitudes. Nevertheless, the ionization at higher altitude is insufficient to obscure the impact of Saturn s magnetosphere protons at a 500 km altitude. The ionization rate at the peak (altitude: 65 km, for all the different conditions) lies between 30 and 40/cu cm/s. Conclusions. These new computations show for the first time the importance of high Z cosmic rays on the ionization of the Titan atmosphere. The updated full ionization profile shape does not differ significantly from that found in our previous calculations (Paper I: Gronoff et al. 2009, 506, 955) but undergoes a strong increase in intensity below an altitude of 400 km, especially between 200 and 400 km altitude where alpha and heavier particles (in the cosmic ray spectrum) are responsible for 40% of the ionization. The comparison of several models of ionization and cosmic ray spectra (in

  18. Far-IR spectroscopy of the galactic center: Neutral and ionized gas in the central 10 pc of the galaxy

    NASA Technical Reports Server (NTRS)

    Hollenbach, D. J.; Watson, D. M.; Townes, C. H.; Dinerstein, H. L.; Hollenbach, D.; Lester, D. F.; Werner, M.; Storey, J. W. V.

    1983-01-01

    The 3P1 - 3P2 fine structure line emission from neutral atomic oxygen at 63 microns in the vicinity of the galactic center was mapped. The emission is extended over more than 4' (12 pc) along the galactic plane, centered on the position of Sgr A West. The line center velocities show that the O I gas is rotating around the galactic center with an axis close to that of the general galactic rotation, but there appear also to be noncircular motions. The rotational velocity at R is approximately 1 pc corresponds to a mass within the central pc of about 3 x 10(6) solar mass. Between 1 and 6 pc from the center the mass is approximately proportional to radius. The (O I) line probability arises in a predominantly neutral, atomic region immediately outside of the ionized central parsec of out galaxy. Hydrogen densities in the (O I) emitting region are 10(3) to 10(6) cm(-3) and gas temperatures are or = 100 K. The total integrated luminosity radiated in the line is about 10(5) solar luminosity, and is a substantial contribution to the cooling of the gas. Photoelectric heating or heating by ultraviolet excitation of H2 at high densities (10(5) cm(-3)) are promising mechanisms for heating of the gas, but heating due to dissipation of noncircular motions of the gas may be an alternative possibility. The 3P1 - 3P0 fine structure line of (O III) at 88 microns toward Sgr A West was also detected. The (O III) emission comes from high density ionized gas (n 10(4) cm(-3)), and there is no evidence for a medium density region (n 10(3) cm(-3)), such as the ionized halo in Sgr A West deduced from radio observations. This radio halo may be nonthermal, or may consist of many compact, dense clumps of filaments on the inner edges of neutral condensations at R or = 2 pc.

  19. Gas chromatography-microchip atmospheric pressure chemical ionization-mass spectrometry.

    PubMed

    Ostman, Pekka; Luosujärvi, Laura; Haapala, Markus; Grigoras, Kestas; Ketola, Raimo A; Kotiaho, Tapio; Franssila, Sami; Kostiainen, Risto

    2006-05-01

    An atmospheric pressure chemical ionization (APCI) microchip is presented for combining a gas chromatograph (GC) to a mass spectrometer (MS). The chip includes capillary insertion channel, stopper, vaporizer channel, nozzle and nebulizer gas inlet fabricated on the silicon wafer, and a platinum heater sputtered on a glass wafer. These two wafers are joined by anodic bonding creating a two-dimensional version of an APCI microchip. The sample from GC is directed via heated transfer line capillary to the vaporizer channel of the APCI chip. The etched nozzle forms narrow sample plume, which is ionized by an external corona discharge needle, and the ions are analyzed by a mass spectrometer. The GC-microchip APCI-MS combination provides an efficient method for qualitative and quantitative analysis. The spectra produced by microchip APCI show intensive protonated molecule and some fragmentation products as in classical chemical ionization for structure elucidation. In quantitative analysis the GC-microchip APCI-MS showed good linearity (r(2) = 0.9989) and repeatability (relative standard deviation 4.4%). The limits of detection with signal-to-noise ratio of three were between 0.5 and 2 micromol/L with MS mode using selected ion monitoring and 0.05 micromol/L with MS/MS using multiple reaction monitoring.

  20. Femtosecond Dynamics and Multiphoton Ionization driven with an Intense High Order Harmonic Source

    NASA Astrophysics Data System (ADS)

    van Tilborg, Jeroen; Allison, Tom; Wright, Travis; Hertlein, Marc; Falcone, Roger; Liu, Yanwei; Merdji, Hamed; Belkacem, Ali

    2009-05-01

    We have constructed a high intensity high order harmonic source at the Lawrence Berkeley National Lab delivering ˜10^9 extreme ultraviolet photons/shot on a gas target and used it to observe multiphoton ionization and conduct femtosecond EUV-pump IR-probe experiments. Following excitation by 20-25 eV photons, we observed that the excited ethylene cation (H2C-CH2)^+ experienced isomerization to the ethylidene configuration (HC-CH3)^+ in 50±25 fs, followed by an H2 stretch motion. Experimental data and analysis from several experiments as well as a future outlook of our efforts will be presented.

  1. Femtosecond dynamics and multiphoton ionization driven with an intense high order harmonic source

    NASA Astrophysics Data System (ADS)

    van Tilborg, J.; Allison, T. K.; Wright, T. W.; Hertlein, M. P.; Liu, Y.; Merdji, H.; Falcone, R. W.; Belkacem, A.

    2009-11-01

    We have constructed a high intensity high order harmonic source delivering ~ 109 extreme ultraviolet photons/shot on a gas target and used it to observe multiphoton ionization and conduct femtosecond EUV-pump IR-probe experiments. Following excitation by 20-25 eV photons, we observed that the excited ethylene cation (H2C-CH2)+ experienced isomerization to the ethylidene configuration (HC-CHs)+ in 50±25 fs, followed by an H2 stretch motion. Experimental data and analysis from several other performed and planned experiments will be presented as well.

  2. Ionized Gas in E/S0 Galaxies with Dust Lanes

    NASA Astrophysics Data System (ADS)

    Funes, Jose G.; J., S.; Finkelman, I.; Borsch, N.; Vaisanen, P.; Kniazev, A.

    2011-01-01

    We present results from an ongoing program to study the properties of dust and ionized gas in E/S0 galaxies with dust lanes. Our observational program comprises of H-alpha and broad-band images obtained with the SAAO 1.9m, the VATT 1.8m and the 1m telescope on WO. A detailed analysis of 30 galaxies shows the presence of a diffusely distributed ionized gas component in most objects. The extended gas morphology is typically smooth and closely follows the dust structure, with a clear correlation between the mass of both components. The dust content in each galaxy is estimated by measuring the extinction by the extragalactic dust in the dark lanes. The derived extinction law is used to correct the measured colors for intrinsic dust extinction and the data are fitted with a stellar population synthesis model. We find that the line-emission and colors of most objects are consistent with the presence of an “old” stellar population ( 10 Gyr) and a small fraction of a “young” population ( 10- 100 Myr). The younger stellar population may have formed at a later stage of the evolution of the galaxy through either a merger event or a secondary star-formation burst. Strong evidence for the external origin of the ISM is provided by the apparent inclination of the dust and ionized gas disks with respect to the galactic plane in a large fraction of our sample galaxies. Further spectroscopic observations will be obtained to study the gaseous disks dynamics and to characterize the underlying stellar populations for evidence of multiple phases of star formation and assembly history.

  3. Gas Chromatography/Atmospheric Pressure Chemical Ionization Tandem Mass Spectrometry for Fingerprinting the Macondo Oil Spill.

    PubMed

    Lobodin, Vladislav V; Maksimova, Ekaterina V; Rodgers, Ryan P

    2016-07-05

    We report the first application of a new mass spectrometry technique (gas chromatography combined to atmospheric pressure chemical ionization tandem mass spectrometry, GC/APCI-MS/MS) for fingerprinting a crude oil and environmental samples from the largest accidental marine oil spill in history (the Macondo oil spill, the Gulf of Mexico, 2010). The fingerprinting of the oil spill is based on a trace analysis of petroleum biomarkers (steranes, diasteranes, and pentacyclic triterpanes) naturally occurring in crude oil. GC/APCI enables soft ionization of petroleum compounds that form abundant molecular ions without (or little) fragmentation. The ability to operate the instrument simultaneously in several tandem mass spectrometry (MS/MS) modes (e.g., full scan, product ion scan, reaction monitoring) significantly improves structural information content and sensitivity of analysis. For fingerprinting the oil spill, we constructed diagrams and conducted correlation studies that measure the similarity between environmental samples and enable us to differentiate the Macondo oil spill from other sources.

  4. Multiple ionization of rare gas atoms irradiated with intense VUV radiation.

    PubMed

    Wabnitz, H; de Castro, A R B; Gürtler, P; Laarmann, T; Laasch, W; Schulz, J; Möller, T

    2005-01-21

    The interaction of intense vacuum-ultraviolet radiation from a free-electron laser with rare gas atoms is investigated. The ionization products of xenon and argon atomic beams are analyzed with time-of-flight mass spectroscopy. At 98 nm wavelength and approximately 10(13) W/cm(2) multiple charged ions up to Xe6+ (Ar4+) are detected. From the intensity dependence of multiple charged ion yields the mechanisms of multiphoton processes were derived. In the range of approximately 10(12)-10(13) W/cm(2) the ionization is attributed to sequential multiphoton processes. The production of multiple charged ions saturates at 5-30 times lower power densities than at 193 and 564 nm wavelength, respectively.

  5. High efficiency gas burner

    DOEpatents

    Schuetz, Mark A.

    1983-01-01

    A burner assembly provides for 100% premixing of fuel and air by drawing the air into at least one high velocity stream of fuel without power assist. Specifically, the nozzle assembly for injecting the fuel into a throat comprises a plurality of nozzles in a generally circular array. Preferably, swirl is imparted to the air/fuel mixture by angling the nozzles. The diffuser comprises a conical primary diffuser followed by a cusp diffuser.

  6. The use of ionization electron columns for space-charge compensation in high intensity proton accelerators

    SciTech Connect

    Shiltsev, V.; Alexahin, Y.; Kamerdzhiev, V.; Kapin, V.; Kuznetsov, G.; /Fermilab

    2009-01-01

    We discuss a recent proposal to use strongly magnetized electron columns created by beam ionization of the residual gas for compensation of space charge forces of high intensity proton beams in synchrotrons and linacs. The electron columns formed by trapped ionization electrons in a longitudinal magnetic field that assures transverse distribution of electron space charge in the column is the same as in the proton beam. Electrostatic electrodes are used to control the accumulation and release of the electrons. Ions are not magnetized and drift away without affecting the compensation. Possible technical solution for the electron columns is presented. We also discuss the first numerical simulation results for space-charge compensation in the FNAL Booster and results of relevant beam studies in the Tevatron.

  7. The Use of Ionization Electron Columns for Space-Charge Compensation in High Intensity Proton Accelerators

    SciTech Connect

    Shiltsev, V.; Alexahin, Y.; Kamerdzhiev, V.; Kapin, V.; Kuznetsov, G.

    2009-01-22

    We discuss a recent proposal to use strongly magnetized electron columns created by beam ionization of the residual gas for compensation of space charge forces of high intensity proton beams in synchrotrons and linacs. The electron columns formed by trapped ionization electrons in a longitudinal magnetic field that assures transverse distribution of electron space charge in the column is the same as in the proton beam. Electrostatic electrodes are used to control the accumulation and release of the electrons. Ions are not magnetized and drift away without affecting the compensation. Possible technical solution for the electron columns is presented. We also discuss the first numerical simulation results for space-charge compensation in the FNAL Booster and results of relevant beam studies in the Tevatron.

  8. Effect Of Feedback On The Escape Of Ionizing Radiation From High-Z Galaxies

    NASA Astrophysics Data System (ADS)

    Trebitsch, Maxime; Blaizot, Jérémy; Rosdahl, Joakim; Devriendt, Julien; Slyz, Adrianne

    2017-06-01

    Quantifying how much of the ionizing radiation produced in high-redshift galaxies escapes in the IGM is one of the main challenges in understanding the sources of reionization. We investigate the radiative properties of simulated low mass galaxies (halos of a few 109 Msun at z=6), where radiation is modelled on-the-fly, and different sources of feedback (from stars and AGN) are included. Using radiation-hydrodynamic simulations performed with Ramses-RT we study how the energy and momentum input from supernovae and black hole activity modulates the properties of the interstellar medium and therefore how, and how many, photons can escape from the galaxy. I will present simulations showing (Trebitsch et al. 2017, https://arxiv.org/abs/1705.00941) that stellar feedback has a pivotal role in regulating the escape fraction in dwarf galaxies. Supernovae carve holes in the gas distribution, through which ionizing photons can escape.

  9. The ionized gas in the central region of NGC 5253. 2D mapping of the physical and chemical properties

    NASA Astrophysics Data System (ADS)

    Monreal-Ibero, A.; Walsh, J. R.; Vílchez, J. M.

    2012-08-01

    Context. Blue compact dwarf (BCD) galaxies constitute the ideal laboratories to test the interplay between massive star formation and the surrounding gas. As one of the nearest BCD galaxies, NGC 5253 was previously studied with the aim to elucidate in detail the starburst interaction processes. Some open issues regarding the properties of its ionized gas still remain to be addressed. Aims: The 2D structure of the main physical and chemical properties of the ionized gas in the core of NGC 5253 has been studied. Methods: Optical integral field spectroscopy (IFS) data has been obtained with FLAMES Argus and lower resolution gratings of the Giraffe spectrograph. Results: We derived 2D maps for different tracers of electron density (ne), electron temperature (Te) and ionization degree. The maps for ne as traced by [O ii], [S ii], [Fe iii], and [Ar iv] line ratios are compatible with a 3D stratified view of the nebula with the highest ne in the innermost layers and a decrease of ne outwards. 2D maps of Te were measured from [O iii] and [S ii] line ratios; to our knowledge, this is the first time that a Te map based on [S ii] lines for an extragalactic object has been presented. The joint interpretation of the Te([S ii]) and Te([O iii]) maps is consistent with a Te structure in 3D with higher temperatures close to the main ionizing source surrounded by a colder and more diffuse component. The highest ionization degree is found at the peak of emission for the gas with relatively high ionization in the main Giant H ii Region and lower ionization degree delineating the more extended diffuse component. We derived abundances of oxygen, neon, argon, and nitrogen. Abundances for O, Ne and Ar are constant over the mapped area within ≲0.1 dex. The mean 12 + log (O/H) is 8.26 ± 0.04 while the relative abundances of log (N/O), log (Ne/O) and log (Ar/O) were ~-1.32 ± 0.05, -0.65 ± 0.03 and -2.33 ± 0.06, respectively. There are two locations with enhanced N/O. The first (log (N

  10. Ionized gas outflow in the isolated S0 galaxy NGC 4460

    NASA Astrophysics Data System (ADS)

    Moiseev, Alexei; Karachentsev, Igor; Kaisin, Serafim

    2010-04-01

    We used integral-field and long-slit spectroscopy to study a bright extended nebulosity recently discovered in the isolated lenticular galaxy NGC 4460 during an Hα survey of nearby galaxies. An analysis of archival Sloan Digital Sky Survey, GALEX and Hubble Space Telescope images indicates that current star formation is entirely concentrated in the central kiloparsec of the galaxy disc. The observed ionized gas parameters (morphology, kinematics and ionization state) can be explained by a gas outflow above the plane of the galaxy, caused by star formation in the circumnuclear region. Galactic wind parameters in NGC 4460 (outflow velocity, total kinetic energy) are several times smaller, compared with the known galactic wind in NGC 253, which is explained by the substantially lower total star formation rate. We discuss the cause of the star formation processes in NGC 4460 and in two other known isolated lenticular (S0) and elliptical (E) galaxies of the Local Volume: NGC 404 and 855. We provide evidence suggesting that the feeding of isolated galaxies by intergalactic gas on a cosmological time-scale is a steady process without significant variations. Based on observations collected with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, which is operated under the financial support of the Science Department of Russia (registration number 01-43). E-mail: moisav@gmail.com

  11. Ionization steps and phase-space metamorphoses in the pulsed microwave ionization of highly excited hydrogen atoms

    SciTech Connect

    Bayfield, J.E.; Luie, S.Y.; Perotti, L.C.; Skrzypkowski, M.P.

    1996-01-01

    As the peak electric field of the microwave pulse is increased, steps in the classical microwave ionization probability of the highly excited hydrogen atom are produced by phase-space metamorphosis. They arise from new layers of Kolmogorov-Arnold-Moser (KAM) islands being exposed as KAM surfaces are destroyed. Both quantum numerical calculations and laboratory experiments exhibit the ionization steps, showing that such metamorphoses influence pulsed semiclassical systems. {copyright} {ital 1996 The American Physical Society.}

  12. The Ionized Gas and Nuclear Environment in NGC 3783. IV; Variability and Modeling of the 900 ks CHANDRA Spectrum

    NASA Technical Reports Server (NTRS)

    Netzer, Hagai; Kaspi, Shai; Behar, Ehud; Brandt, W. N.; Chelouche, Doron; George, Ian M.; Crenshaw, D. Michael; Gabel, Jack R.; Hamann, Frederick W.; George, Steven B.

    2003-01-01

    We present a detailed analysis of the 900 ks spectrum of NGC3783 obtained by Chandra in 2000-2001 (Kaspi et al. 2002). We split the data in various ways to look for time dependent and luminosity dependent spectral variations. This analysis, the measured equivalent widths of a large number of X-ray lines, and our photoionization calculations, lead us to the following conclusions: 1) NGC 3783 fluctuated in luminosity, by a factor N 1.5, during individual 170 ks observations. The fluctuations were not associated with significant spectral variations. 2) On a longer time scale, of 20-120 days, we discovered two very different spectral shapes that are noted the high state and the low state spectra. The observed changes between the two can be described as the appearance and disappearance of a soft continuum component. The spectral variations are not related, in a simple way, to the brightening or the fading of the short wavelength continuum, as observed in other objects. NGC3783 seems to be the first AGN to show this unusual behavior. 3) The appearance of the soft continuum component is consistent with beeing the only spectral variation and there is no need to invoke changes in the absorber s opacity. In particular, all absorption lines with reliable measurements show the same equivalent width, within the observational uncertainties, during high and low states. 4) Photoionization model calculations show that a combination of three ionization components, each split into two kinematic components, explain very well the intensity of almost all absorption lines and the bound-free absorption. The components span a large range of ionization and a total column of about 3 x 10(exp 22) per square centimeter Moreover, all components are thermally stable and are situated on the vertical branch of the stability curve.. This means that they are in pressure equilibrium and perhaps occupy the same volume of space. This is the first detection of such a multi-component equilibrium gas in

  13. Highly ionized disc and transient outflows in the Seyfert galaxy IRAS 18325-5926

    NASA Astrophysics Data System (ADS)

    Iwasawa, K.; Fabian, A. C.; Kara, E.; Reynolds, C. S.; Miniutti, G.; Tombesi, F.

    2016-08-01

    We report on strong X-ray variability and the Fe K-band spectrum of the Seyfert galaxy IRAS 18325-5926 obtained from the 2001 XMM-Newton EPIC pn observation with a duration of ~120 ks. While the X-ray source is highly variable, the 8-10 keV band shows larger variability than that of the lower energies. Amplified 8-10 keV flux variations are associated with two prominent flares of the X-ray source during the observation. The Fe K emission is peaked at 6.6 keV with moderate broadening. It is likely to originate from a highly ionized disc with an ionization parameter of log ξ ≃ 3. The Fe K line flux responds to the main flare, which supports its disc origin. A short burst of the Fe line flux has no relation to the continuum brightness, for which we have no clear explanation. We also find transient, blueshifted Fe K absorption features that can be identified with high-velocity (~0.2c) outflows of highly ionized gas, as found in other active galaxies. The deepest absorption feature appears only briefly (~1 h) at the onset of the main flare and disappears when the flare declines. The rapid evolution of the absorption spectrum makes this source peculiar among the active galaxies with high-velocity outflows. Another detection of the absorption feature also precedes the other flare. The variability of the absorption feature partly accounts for the excess variability in the 8-10 keV band where the absorption feature appears. Although no reverberation measurement is available, the black hole mass of ~2 × 106M⊙ is inferred from the X-ray variability. When this mass is assumed, the black hole is accreting at around the Eddington limit, which may fit the highly ionized disc and strong outflows observed in this galaxy.

  14. WARM IONIZED GAS REVEALED IN THE MAGELLANIC BRIDGE TIDAL REMNANT: CONSTRAINING THE BARYON CONTENT AND THE ESCAPING IONIZING PHOTONS AROUND DWARF GALAXIES

    SciTech Connect

    Barger, K. A.; Haffner, L. M.; Bland-Hawthorn, J. E-mail: haffner@astro.wisc.edu

    2013-07-10

    The Magellanic System includes some of the nearest examples of galaxies disturbed by galaxy interactions. These interactions have redistributed much of their gas into the halos of the Milky Way (MW) and the Magellanic Clouds. We present Wisconsin H{alpha} Mapper kinematically resolved observations of the warm ionized gas in the Magellanic Bridge over the velocity range of +100 to +300 km s{sup -1} in the local standard of rest reference frame. These observations include the first full H{alpha} intensity map and the corresponding intensity-weighted mean velocity map of the Magellanic Bridge across (l, b) = (281 Degree-Sign .5, -30 Degree-Sign .0) to (302. Degree-Sign 5, -46. Degree-Sign 7). Using the H{alpha} emission from the Small Magellanic Cloud (SMC)-Tail and the Bridge, we estimate that the mass of the ionized material is between (0.7-1.7) Multiplication-Sign 10{sup 8} M{sub Sun }, compared to 3.3 Multiplication-Sign 10{sup 8} M{sub Sun} for the neutral mass over the same region. The diffuse Bridge is significantly more ionized than the SMC-Tail, with an ionization fraction of 36%-52% compared to 5%-24% for the Tail. The H{alpha} emission has a complex multiple-component structure with a velocity distribution that could trace the sources of ionization or distinct ionized structures. We find that incident radiation from the extragalactic background and the MW alone are insufficient to produced the observed ionization in the Magellanic Bridge and present a model for the escape fraction of the ionizing photons from both the SMC and Large Magellanic Cloud (LMC). With this model, we place an upper limit of 4.0% for the average escape fraction of ionizing photons from the LMC and an upper limit of 5.5% for the SMC. These results, combined with the findings of a half a dozen other studies for dwarf galaxies in different environments, provide compelling evidence that only a small percentage of the ionizing photons escape from dwarf galaxies in the present epoch to

  15. Ionization gas sensing of the ion flow current in a microtripolar electrode system with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hou, Zhongyu; Cai, Bingchu; Xu, Dong

    2008-06-01

    We report the tests of a tripolar on-chip microelectrode system with carbon nanotubes, where the ion flow current (Ii) and the partial discharge current produced by the field ionization process of gaseous molecules can be measured to characterize the gas species and concentration. A theoretical account is given regarding the underlying differences between their sensing mechanisms. Further, comparative analysis of these two outputs in response to the concentration dynamic changes of ethanol/acetone in N2 demonstrates the explicit cases of improved sensitivity and selectivity of the Ii measurement.

  16. High ratio recirculating gas compressor

    DOEpatents

    Weinbrecht, John F.

    1989-01-01

    A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor.

  17. High ratio recirculating gas compressor

    DOEpatents

    Weinbrecht, J.F.

    1989-08-22

    A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor. 10 figs.

  18. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, EXPLOSIVES DETECTION TECHNOLOGY, SRI INSTRUMENTS, MODEL 8610C, GAS CHROMATOGRAPH/THERMIONIC IONIZATION DETECTION

    EPA Science Inventory

    The SRI Model 86 1 OC gas chromatograph (GC) is a transportable instrument that can provide on-site analysis of soils for explosives. Coupling this transportable gas chromatograph with a thermionic ionization detector (TID) allows for the determination of explosives in soil matri...

  19. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, EXPLOSIVES DETECTION TECHNOLOGY, SRI INSTRUMENTS, MODEL 8610C, GAS CHROMATOGRAPH/THERMIONIC IONIZATION DETECTION

    EPA Science Inventory

    The SRI Model 86 1 OC gas chromatograph (GC) is a transportable instrument that can provide on-site analysis of soils for explosives. Coupling this transportable gas chromatograph with a thermionic ionization detector (TID) allows for the determination of explosives in soil matri...

  20. Field ionization of Rydberg atoms for high-brightness electron and ion beams

    NASA Astrophysics Data System (ADS)

    McCulloch, A. J.; Speirs, R. W.; Grimmel, J.; Sparkes, B. M.; Comparat, D.; Scholten, R. E.

    2017-06-01

    We present an ionization mechanism for use in a cold atom electron source with the goal of producing highly monochromatic electron beams. We experimentally produce a map of the Stark states of 85Rb below the ionization threshold and identify states that undergo selective field ionization. The properties of an electron beam produced by field-assisted ionization of such states are quantified. A theoretical framework is established to predict the improvement to beam quality when ionization is conducted above the ionization threshold, where ionization conditions are typically more favorable than below the threshold. Calculations suggest that selective ionization of Rydberg states may offer a pathway to the production of high-brightness, highly monochromatic ion and electron beams.

  1. Internally heated membrane interfaced to a gas chromatography flame ionization detector.

    PubMed

    Kanu, A Bakarr; Thomas, C L P

    2013-07-15

    Volatile Organic Compounds (VOCs) mixtures in aqueous solutions have been investigated using a simple and efficient all-in-one on-line sampling, isolation, enrichment and pre-concentration internally heated membrane connected to a gas chromatography flame ionization detector (GC-FID). In our previous study with the internally heated membrane, no GC column was used in the instrument. In this new study, we introduce a GC column in the instrument design and this makes it possible for mixtures to be investigated. This new experimental design enabled high resolution separation of analyte mixtures capable of being adsorbed, diffused, and desorbed from the device for detection with an FID. With the new design we present data from investigation of competitive adsorption effects on the membrane. The data showed that analyte adsorption and diffusion onto the membrane can be affected when mixtures of analytes are introduced. The application of multiple linear regressions approach to the data enabled us to correct for the problem of competitive adsorption. Analyte adsorption and diffusion was affected by the diffusion coefficients of the analytes; the higher the diffusion coefficient the better the extraction from the membrane. Increasing the sampling time from 1 to 4 min increases the response by 77%. The sampling time responses were linear up to 4 min sampling time. Above 4 min sampling time, the data deviate from linearity. The effect of adding salt to standards has no effect on analyte absorption onto the membrane. The detection limits for key VOCs studied with an internal standard calibration ranged from 0.2 to 194 ng cm(-3).

  2. High-efficiency electron ionizer for a mass spectrometer array

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor); Darrach, Murray R. (Inventor); Orient, Otto J. (Inventor)

    2001-01-01

    The present invention provides an improved electron ionizer for use in a quadrupole mass spectrometer. The improved electron ionizer includes a repeller plate that ejects sample atoms or molecules, an ionizer chamber, a cathode that emits an electron beam into the ionizer chamber, an exit opening for excess electrons to escape, at least one shim plate to collimate said electron beam, extraction apertures, and a plurality of lens elements for focusing the extracted ions onto entrance apertures.

  3. High field – low energy muon ionization cooling channel

    DOE PAGES

    Sayed, Hisham Kamal; Palmer, Robert B.; Neuffer, David

    2015-09-04

    Muon beams are generated with large transverse and longitudinal emittances. In order to achieve the low emittances required by a muon collider, within the short lifetime of the muons, ionization cooling is required. Cooling schemes have been developed to reduce the muon beam 6D emittances to ≈ 300 μm–rad in transverse and ≈ 1–1.5 mm in longitudinal dimensions. The transverse emittance has to be further reduced to ≈ 50–25 μm–rad with an upper limit on the longitudinal emittance of ≈ 76 mm in order to meet the high-energy muon collider luminosity requirements. Earlier studies of the transverse cooling of lowmore » energy muon beams in high field magnets showed a promising performance, but did not include transverse or longitudinal matching between the stages. In this study we present the first complete design of the high field-low energy ionization cooling channel with transverse and longitudinal matching. The channel design was based on strong focusing solenoids with fields of 25–30 T and low momentum muon beam starting at 135 MeV/c and gradually decreasing. The cooling channel design presented here is the first to reach ≈ 50 micron scale emittance beam. As a result, we present the channel’s optimized design parameters including the focusing solenoid fields, absorber parameters and the transverse and longitudinal matching.« less

  4. Acceleration of Vaporization, Atomization, and Ionization Efficiencies in Inductively Coupled Plasma by Merging Laser-Ablated Particles with Hydrochloric Acid Gas.

    PubMed

    Nakazawa, Takashi; Izumo, Saori; Furuta, Naoki

    2016-01-01

    To accelerate the vaporization, atomization, and ionization efficiencies in laser ablation inductively coupled plasma mass spectrometry, we merged HCl gas with laser-ablated particles before introduction into the plasma, to convert their surface constituents from oxides to lower-melting chlorides. When particles were merged with HCl gas generated from a HCl solution at 200°C, the measured concentrations of elements in the particles were 135% higher on average than the concentrations in particles merged with ultrapure water vapor. Particle corrosion and surface roughness were observed by scanning electron microscopy, and oxide conversion to chlorides was confirmed by X-ray photoelectron spectroscopy. Under the optimum conditions, the recoveries of measured elements improved by 23% on average, and the recoveries of elements with high-melting oxides (Sr, Zr, and Th) improved by as much as 36%. These results indicate that vaporization, atomization, and ionization in the ICP improved when HCl gas was merged with the ablated particles.

  5. THE CURIOUS CASE OF GLASS I: HIGH IONIZATION AND VARIABILITY OF DIFFERENT TYPES

    SciTech Connect

    Kruger, Andrew J.; Richter, Matthew J.; Carr, John S.; Najita, Joan R.; Moerchen, Margaret M.; Doppmann, Greg W.; Seifahrt, Andreas

    2013-02-20

    Our Spitzer IRS observation of the infrared companion Glass Ib revealed fine-structure emission with high ionization ([Ne III]/[Ne II] = 2.1 and [S IV]/[S III] = 0.6) that indicates that the gas is likely illuminated by hard radiation. While models suggest that extreme-ultraviolet radiation could be present in T Tauri stars, this is the first detection of [S IV] and such a high [Ne III]/[Ne II] ratio in a young star. We also find that Glass Ib displays the molecules HCN, CO{sub 2}, and H{sub 2}O in emission. Here we investigate the Glass I binary system and consider possible mechanisms that may have caused the high ionization, whether from an outflow or disk irradiation. We also model the spectral energy distributions of Glass Ia and Ib to test if the system is a young member of the Chameleon I star-forming region, and we consider other possible classifications for the system. We find that Glass Ib is highly variable, showing changes in continuum strength and emission features at optical, near-infrared, and mid-infrared wavelengths. The optical light curve indicates that a central stellar component in Glass Ib became entirely visible for 2.5 years beginning in mid-2002 and possibly displayed periodic variability with repeated, short-period dimming during that time. As the fine-structure emission was not detected in observations before or after our Spitzer IRS observation, we explore whether the variable nature of Glass Ib is related to the gas being highly ionized, possibly due to variable accretion or an X-ray flare.

  6. MAGNETIZED GAS IN THE SMITH HIGH VELOCITY CLOUD

    SciTech Connect

    Hill, Alex S.; McClure-Griffiths, Naomi M.; Mao, S. A.; Benjamin, Robert A.; Lockman, Felix J. E-mail: naomi.mcclure-griffiths@csiro.au E-mail: benjamir@uww.edu

    2013-11-01

    We report the first detection of magnetic fields associated with the Smith High Velocity Cloud. We use a catalog of Faraday rotation measures toward extragalactic radio sources behind the Smith Cloud, new H I observations from the Robert C. Byrd Green Bank Telescope, and a spectroscopic map of Hα from the Wisconsin H-Alpha Mapper Northern Sky Survey. There are enhancements in rotation measure (RM) of ≈100 rad m{sup –2} which are generally well correlated with decelerated Hα emission. We estimate a lower limit on the line-of-sight component of the field of ≈8 μG along a decelerated filament; this is a lower limit due to our assumptions about the geometry. No RM excess is evident in sightlines dominated by H I or Hα at the velocity of the Smith Cloud. The smooth Hα morphology of the emission at the Smith Cloud velocity suggests photoionization by the Galactic ionizing radiation field as the dominant ionization mechanism, while the filamentary morphology and high (≈1 Rayleigh) Hα intensity of the lower-velocity magnetized ionized gas suggests an ionization process associated with shocks due to interaction with the Galactic interstellar medium. The presence of the magnetic field may contribute to the survival of high velocity clouds like the Smith Cloud as they move from the Galactic halo to the disk. We expect these data to provide a test for magnetohydrodynamic simulations of infalling gas.

  7. Interrelated structures of the transport shock and collisional relaxation layer in a multitemperature, multilevel ionized gas

    NASA Technical Reports Server (NTRS)

    Vinolo, A. R.; Clarke, J. H.

    1972-01-01

    The gas dynamic structures of the transport shock and the downstream collisional relaxation layer are evaluated for partially ionized monatomic gases. Elastic and inelastic collisional nonequilibrium effects are taken into consideration. Three electronic levels are accounted for in the microscopic model of the atom. Nonequilibrium processes with respect to population of levels and species plus temperature are considered. By using an asymptotic technique the shock morphology is found on a continuum flow basis. The asymptotic procedure gives two distinct layers in which the nonequilibrium effects to be considered are different. A transport shock appears as the inner solution to an outer collisional relaxation layer in which the gas reaches local equilibrium. A family of numerical examples is displayed for different flow regimes. Argon and helium models are used in these examples.

  8. High Excitation Gas and ISM

    NASA Technical Reports Server (NTRS)

    Peeters, E.; Martin-Hernandez, N. L.; Rodriguez-Fernandez, N. J.; Tielens, A. G. G. M.

    2004-01-01

    An overview is given of ISO results on regions of high excitation ISM and gas, i.e. HII regions, the Galactic Centre and Supernovae Remnants. IR emission due to fine-structure lines, molecular hydrogen, silicates, polycyclic aromatic hydrocarbons and dust are summarized, their diagnostic capabilities illustrated and their implications highlighted.

  9. Turbulent Dynamo in a Conducting Fluid and a Partially Ionized Gas

    NASA Astrophysics Data System (ADS)

    Xu, Siyao; Lazarian, A.

    2016-12-01

    By following the Kazantsev theory and taking into account both microscopic and turbulent diffusion of magnetic fields, we develop a unified treatment of the kinematic and nonlinear stages of a turbulent dynamo process, and we study the dynamo process for a full range of magnetic Prandtl number P m and ionization fractions. We find a striking similarity between the dependence of dynamo behavior on P m in a conducting fluid and { R } (a function of ionization fraction) in a partially ionized gas. In a weakly ionized medium, the kinematic stage is largely extended, including not only exponential growth but a new regime of dynamo characterized by a linear-in-time growth of magnetic field strength, and the resulting magnetic energy is much higher than the kinetic energy carried by viscous-scale eddies. Unlike the kinematic stage, the subsequent nonlinear stage is unaffected by microscopic diffusion processes and has a universal linear-in-time growth of magnetic energy with the growth rate as a constant fraction 3/38 of the turbulent energy transfer rate, showing good agreement with earlier numerical results. Applying the analysis to the first stars and galaxies, we find that the kinematic stage is able to generate a field strength only an order of magnitude smaller than the final saturation value. But the generation of large-scale magnetic fields can only be accounted for by the relatively inefficient nonlinear stage and requires longer time than the free-fall time. It suggests that magnetic fields may not have played a dynamically important role during the formation of the first stars.

  10. High-sensitivity elemental ionization for quantitative detection of halogenated compounds.

    PubMed

    Wang, Haopeng; Minardi, Carina S; Badiei, Hamid; Kahen, Kaveh; Jorabchi, Kaveh

    2015-12-21

    The rising importance of organohalogens in environmental, pharmaceutical, and biological applications has drawn attention to analysis of these compounds in recent years. Elemental mass spectrometry (MS) is particularly advantageous in this regard because of its ability to quantify without compound-specific standards. However, low sensitivity of conventional elemental MS for halogens has hampered applications of this powerful method in organohalogen analyses. To this end, we have developed a high-sensitivity elemental ion source compatible with widely available atmospheric-sampling mass spectrometers. We utilize a helium-oxygen plasma for atomization followed by negative ion formation in plasma afterglow, a configuration termed as plasma-assisted reaction chemical ionization (PARCI). The effect of oxygen on in-plasma and afterglow reactions is investigated, leading to fundamental understanding of ion generation processes as well as optimized operating conditions. Coupled to a gas chromatograph, PARCI shows constant ionization efficiency for F, Cl, and Br regardless of the chemical structure of the compounds. Negative ionization in the afterglow improves halide ion formation efficiency and eliminates isobaric interferences, offering sub-picogram elemental detection for F, Cl, and Br using low-resolution MS. Notably, the detection limit for F is about one order of magnitude better than other elemental MS techniques. The high sensitivity and facile adoptability of PARCI pave the way for combined elemental-molecular characterization, a comprehensive analytical scheme for rapid identification and quantification of organohalogens.

  11. High pressure gas metering project

    SciTech Connect

    Tripp, L.R.

    1980-07-07

    The initial research and development of a system that uses high pressure helium gas to pressurize vessels over a wide range of pressurization rates, vessel volumes, and maximum test pressures are described. A method of controlling the mass flow rate in a test vessel was developed by using the pressure difference across a capillary tube. The mass flow rate is related to the pressurization rate through a real gas equation of state. The resulting mass flow equation is then used in a control algorithm. Plots of two typical pressurization tests run on a manually operated system are included.

  12. Ambient gas/particle partitioning. 1. Sorption mechanisms of apolar, polar, and ionizable organic compounds.

    PubMed

    Arp, Hans Peter H; Schwarzenbach, René P; Goss, Kai-Uwe

    2008-08-01

    There remain several ambiguities in the literature regarding the dominating sorption mechanisms involved in gas/particle partitioning, particularly for polar and ionizable compounds. The various hypothetical mechanisms would depend differently on relative humidity (RH) and the presence of various aerosol components. Thus, in order to resolve these ambiguities, here we measured the RH-dependency of gas/particle partitioning constants, K(ip), for four diverse aerosol samples and a large set of chemicals covering apolar, polar, and ionizable organic compounds. In addition, we also removed the water-soluble components from two ambient particle samples to study how their presence influences sorption behavior. The measured K(ip) values collectively indicate that a dual-phase sorption mechanism is occurring, in which organic compounds partition into a RH-independent water-insoluble organic matter phase and additionally into a RH-dependent mixed-aqueous phase. All K(ip) values could be successfully fitted to a RH-dependent dual-phase sorption model. The trends in K(ip) data further support findings that the sorption behavior of ambient aerosol samples is different from raw mineral surfaces and soot.

  13. Constraining the ionized gas evolution with CMB-spectroscopic survey cross-correlation

    NASA Astrophysics Data System (ADS)

    Ma, Yin-Zhe

    2017-07-01

    We forecast the prospective constraints on the ionized gas model fgas (z) at different evolutionary epochs via the tomographic cross-correlation between kinetic Sunyaev-Zeldovich (kSZ) effect and the reconstructed momentum field at different redshifts. The experiments we consider are the Planck and CMB Stage-4 survey for CMB and the SDSS-III for the galaxy spectroscopic survey. We calculate the tomographic cross-correlation power spectrum, and use the Fisher matrix to forecast the detectability of different fgas (z) models. We find that for constant fgas model, Planck can constrain the error of fgas (σfgas) at each redshift bin to ∼0.2, whereas four cases of CMB-S4 can achieve σfgas ∼10-3. For fgas (z) =fgas,0 / (1 + z) model the error budget will be slightly broadened. We also investigate the model fgas (z) =fgas,0 /(1 + z) α. Planck is unable to constrain the index of redshift evolution, but the CMB-S4 experiments can constrain the index α to the level of σα ∼ 0.01-0.1. The tomographic cross-correlation method will provide an accurate measurement of the ionized gas evolution at different epochs of the Universe.

  14. Highly informative multiclass profiling of lipids by ultra-high performance liquid chromatography - Low resolution (quadrupole) mass spectrometry by using electrospray ionization and atmospheric pressure chemical ionization interfaces.

    PubMed

    Beccaria, Marco; Inferrera, Veronica; Rigano, Francesca; Gorynski, Krzysztof; Purcaro, Giorgia; Pawliszyn, Janusz; Dugo, Paola; Mondello, Luigi

    2017-08-04

    A simple, fast, and versatile method, using an ultra-high performance liquid chromatography system coupled with a low resolution (single quadrupole) mass spectrometer was optimized to perform multiclass lipid profiling of human plasma. Particular attention was made to develop a method suitable for both electrospray ionization and atmospheric pressure chemical ionization interfaces (sequentially in positive- and negative-ion mode), without any modification of the chromatographic conditions (mobile phase, flow-rate, gradient, etc.). Emphasis was given to the extrapolation of the structural information based on the fragmentation pattern obtained using atmospheric pressure chemical ionization interface, under each different ionization condition, highlighting the complementary information obtained using the electrospray ionization interface, of support for related molecule ions identification. Furthermore, mass spectra of phosphatidylserine and phosphatidylinositol obtained using the atmospheric pressure chemical ionization interface are reported and discussed for the first time. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Dust and ionized gas in elliptical galaxies: Signatures of merging collisions

    NASA Technical Reports Server (NTRS)

    Goudfrooij, Paul; Dejong, Teije

    1993-01-01

    Traditionally elliptical galaxies were thought to be essentially devoid of interstellar matter. However, recent advances in instrumental sensitivity have caused a renaissance of interest in dust and gas in - or associated with - elliptical galaxies. In particular, the technique of co-adding IRAS survey scans has led to the detection of more than half of all ellipticals with BT less than 11 mag. in the Revised Shapley-Ames catalog, indicating the presence of 10(exp 7) - 10(exp 8) solar mass of cold interstellar matter (Jura et al. 1987). In addition, CCD multi-color surface photometry shows dust patches in about 30 percent of the cases studied to date (e.g., Veron-Cetty & Veron 1988). Thorough study of the gas and dust in ellipticals is important to (1) determine its origin (mass-loss from late-type stars, merging collisions with other galaxies or accretion inflows from cooling X-ray gas), and (2) investigate the 3-D shape of ellipticals, as can be derived from the orientation of the dust lanes and the 2-D velocity field of the gas. An important result of our comprehensive CCD imaging program is that a relevant fraction (approximately 40 percent) of the sample objects exhibits dust patches within extended H-alpha+(NII) line-emitting filaments. This common occurrence can be easily accounted for if the dust and gas have an external origin, i.e., mergers or interactions with gas-rich galaxies. Evidence supporting this suggestion: (1) the ionized gas is usually dynamically decoupled from the stellar velocity field (see, e.g., Sharples et al. 1983, Bertola & Bettoni 1988); (2) it is shown in a companion paper (Goudfrooij et al. 1992) that internal stellar mass loss alone can not account for the dust content of elliptical galaxies.

  16. Chemical Ionization Mass Spectrometry Techniques for Measurements of Gas-Phase Ammonia

    NASA Astrophysics Data System (ADS)

    Nowak, J. B.; Neuman, J. A.; Yoshida, K.; Ryerson, T. B.; Huey, L. G.; Tanner, D. J.; Sjostedt, S. J.; Hubler, G.; Fortin, T. J.; Sueper, D. J.; Fehsenfeld, F. C.

    2005-12-01

    Chemical Ionization Mass Spectrometry (CIMS) can be a highly selective technique with fast time response for measuring many atmospheric trace gases (e.g., hydroxyl radical (OH), sulfuric acid (H2SO4), nitric acid (HNO3)). CIMS is highly versatile and has been used under a wide variety of conditions with many different ion-molecule detection schemes, even for detecting the same molecule. Because of its high proton affinity (853.6 kJ/mol), ammonia (NH3) is another ideal candidate for detection by CIMS. NH3, the dominant gas-phase base in the atmosphere, is a precursor of ammonium nitrate and ammonium sulfates, compounds that are important constituents of airborne fine particulate matter that affect air quality. The characterization of three NH3 CIMS instruments: an atmospheric pressure ionization instrument and a low-pressure flow tube reactor instrument, both utilizing protonated ethanol cluster ion chemistry, and a different low-pressure flow tube reactor instrument using protonated acetone dimer ion chemistry, is presented here. Instrument performance is assessed using ambient data from both ground-based and airborne field programs to examine detection sensitivity, background signal, and time response. Laboratory characterization of different inlet materials is also presented. All three instruments used PFA Teflon sampling inlets. Instrumental backgrounds were determined by scrubbing NH3 from ambient air using silicon phosphates that release phosphoric acid when exposed to ambient levels of humidity. Standard addition calibrations were performed using NH3 permeation devices whose output was determined via 185nm optical absorption. Regardless of CIMS technique or ion chemistry used, the observed detection sensitivities were all adequate for detecting changes in NH3 at the 10 pptv level on a 1s timescale. The time responses, defined by a 1/e2 decay in the calibration signal, ranged from 5s to 45s for the different sampling inlet configurations and are rapid enough

  17. Unified first principles description from warm dense matter to ideal ionized gas plasma: electron-ion collisions induced friction.

    PubMed

    Dai, Jiayu; Hou, Yong; Yuan, Jianmin

    2010-06-18

    Electron-ion interactions are central to numerous phenomena in the warm dense matter (WDM) regime and at higher temperature. The electron-ion collisions induced friction at high temperature is introduced in the procedure of ab initio molecular dynamics using the Langevin equation based on density functional theory. In this framework, as a test for Fe and H up to 1000 eV, the equation of state and the transition of electronic structures of the materials with very wide density and temperature can be described, which covers a full range of WDM up to high energy density physics. A unified first principles description from condensed matter to ideal ionized gas plasma is constructed.

  18. Scintillation luminescence for high-pressure xenon gas

    NASA Astrophysics Data System (ADS)

    Kobayashi, S.; Hasebe, N.; Igarashi, T.; Kobayashi, M.-N.; Miyachi, T.; Miyajima, M.; Okada, H.; Okudaira, O.; Tezuka, C.; Yokoyama, E.; Doke, T.; Shibamura, E.; Dmitrenko, V. V.; Ulin, S. E.; Vlasik, K. F.

    2004-09-01

    Scintillation and ionization yields in xenon gas for 5.49MeV alpha-particles were measured in the range of pressure from 0.35 to 3.7MPa and the electric field strength (E) over the number density of xenon atoms (N), E/N from 0 to 5×10-18Vcm2. When our data are normalized at the data point measured by Saito et al., the number of scintillation photons is 2.3×105 while the number of ionization electrons is 2.0×105 at 2.6MPa and at 3.7×10-18Vcm2. The scintillation and ionization yields of xenon doped with 0.2% hydrogen, High-Pressure Xenon gas[H2-0.2%], at 2.6MPa was also measured. Scintillation yield of the Xe-H2 mixture gas is 80% as high as that of pure xenon. It is found that the scintillation yield is luminous enough to generate a trigger pulse of the high-pressure xenon time projection chamber, which is expected as a promising MeV Compton gamma-ray camera.

  19. Propagation direction reversal of ionization zones in the transition between high and low current magnetron sputtering

    SciTech Connect

    School of Materials Science and Engineering, State Key Lab for Materials Processing and Die & Mold Technology, Huazhong University of Science and Technology, Wuhan 430074, China; Department of Physics, University of California Berkeley, Berkeley, California 94720, USA; Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA; Yang, Yuchen; Liu, Jason; Liu, Lin; Anders, André

    2014-12-11

    Past research has revealed the propagation of dense, asymmetric ionization zones in both high and low current magnetron discharges. Here we report about the direction reversal of ionization zone propagation as observed with fast cameras. At high currents, zones move in the E B direction with velocities of 103 to 104 m/s. However at lower currents, ionization zones are observed to move in the opposite, the -E B direction, with velocities ~;; 103 m/s. It is proposed that the direction reversal is associated with the local balance of ionization and supply of neutrals in the ionization zone.

  20. High order harmonic generation in dual gas multi-jets

    SciTech Connect

    Tosa, Valer E-mail: calin.hojbota@itim-cj.ro; Hojbota, Calin E-mail: calin.hojbota@itim-cj.ro

    2013-11-13

    High order harmonic generation (HHG) in gas media suffers from a low conversion efficiency that has its origins in the interaction of the atom/molecule with the laser field. Phase matching is the main way to enhance the harmonic flux and several solutions have been designed to achieve it. Here we present numerical results modeling HHG in a system of multi-jets in which two gases alternate: the first gas jet (for example Ne) generates harmonics and the second one which ionizes easier, recover the phase matching condition. We obtain configurations which are experimentally feasible with respect to pressures and dimensions of the jets.

  1. Extreme ultraviolet spectra of highly ionized oxygen and fluorine

    NASA Technical Reports Server (NTRS)

    Pegg, D. J.; Griffin, P. M.; Haselton, H. H.; Laubert, R.; Mowat, J. R.; Thoe, R. S.; Peterson, R. S.; Sellin, I. A.

    1974-01-01

    The foil-excitation method has been used to study the extreme ultraviolet spectra of highly ionized oxygen and fluorine. Several previously unreported lines in heliumlike fluorine are reported and other newly reported lines in heliumlike oxygen have been measured to higher accuracy. Included in the measurements are certain heliumlike oxygen transitions of significance in interpretation of solar-flare spectral observations. The wavelength determinations are usually in good agreement with calculated results which includes relativistic corrections, but discrepancies arise when nonrelativistic calculations are used. A comparison of the present results and those recently obtained by theta-pinch and laser-induced plasma sources is made for both heliumlike and lithiumlike ions; a few discrepancies occur, with results in most cases in better agreement with relativistically corrected calculations. Certain unidentified lines in the spectra may be attributable to radiative transitions between quartet states of lithiumlike ions.

  2. Forbidden line emission from highly ionized atoms in tokamak plasmas

    NASA Technical Reports Server (NTRS)

    Feldman, U.; Doschek, G. A.; Bhatia, A. K.

    1982-01-01

    Considerable interest in the observation of forbidden spectral lines from highly ionized atoms in tokamak plasmas is related to the significance of such observations for plasma diagnostic applications. Atomic data for the elements Ti Cr, Mn, Fe, Ni, and Kr have been published by Feldman et al. (1980) and Bhatia et al. (1980). The present investigation is concerned with collisional excitation rate coefficients and radiative decay rates, which are interpolated for ions of elements between calcium, and krypton and for levels of the 2s2 2pk, 2s 2p(k+1), and 2p(k+2) configurations, and for the O I, N I, C I, B I, and Be I isoelectronic sequences. The provided interpolated atomic data can be employed to calculate level populations and relative line intensities for ions of the considered sequences, taking into account levels of the stated configurations. Important plasma diagnostic information provided by the forbidden lines includes the ion temperature

  3. The COS-Halos Survey: Origins of the Highly Ionized Circumgalactic Medium of Star-Forming Galaxies

    NASA Astrophysics Data System (ADS)

    Werk, Jessica K.; Prochaska, J. Xavier; Cantalupo, Sebastiano; Fox, Andrew J.; Oppenheimer, Benjamin; Tumlinson, Jason; Tripp, Todd M.; Lehner, Nicolas; McQuinn, Matthew

    2016-12-01

    The total contribution of diffuse halo gas to the galaxy baryon budget strongly depends on its dominant ionization state. In this paper, we address the physical conditions in the highly ionized circumgalactic medium (CGM) traced by {{O}} {{VI}} absorption lines observed in COS-Halos spectra. We analyze the observed ionic column densities, absorption-line widths and relative velocities, along with the ratios of {{N}} {{V}}/{{O}} {{VI}} for 39 fitted Voigt profile components of O vi. We compare these quantities with the predictions given by a wide range of ionization models. Photoionization models that include only extragalactic UV background radiation are ruled out; conservatively, the upper limits to {{N}} {{V}}/{{O}} {{VI}} and measurements of {N}{{O}{{VI}}} imply unphysically large path lengths ≳100 kpc. Furthermore, very broad {{O}} {{VI}} absorption (b > 40 km s-1) is a defining characteristic of the CGM of star-forming L* galaxies. We highlight two possible origins for the bulk of the observed {{O}} {{VI}}: (1) highly structured gas clouds photoionized primarily by local high-energy sources or (2) gas radiatively cooling on large scales behind a supersonic wind. Approximately 20% of circumgalactic O vi does not align with any low-ionization state gas within ±50 km s-1 and is found only in halos with {M}{halo} < 1012 {M}⊙ . We suggest that this type of unmatched O vi absorption traces the hot corona itself at a characteristic temperature of {10}5.5 K. We discuss the implications of these very distinct physical origins for the dynamical state, gas cooling rates, and total baryonic content of L* gaseous halos.

  4. Interplay of mulitphoton and tunneling ionization in short-wavelength-driven high-order harmonic generation

    SciTech Connect

    Gkortsas, Vasileios-Marios; Bhardwaj, Siddharth; Lai, Chien-Jen; Hong, Kyung-Han; Falcao-Filho, Edilson L.; Kaertner, Franz X.

    2011-07-15

    High-order harmonic generation efficiency is theoretically modeled and compared with experiments using 400 and 800 nm driver pulses. It is shown that, for a short drive wavelength and a Keldysh parameter larger than 1, the Ammosov-Delone-Krainov (ADK) ionization model does not give a good agreement between theory and experiment. Since the ADK ionization model only accounts for tunnel ionization, it underestimates the yield of low-order harmonics from the wings of the driver pulse. In contrast, the Yudin-Ivanov ionization model [Phys. Rev. A 64, 013409 (2001)], which accounts for both tunnel and multiphoton ionization, gives much better agreement with the experimental results.

  5. Analysis of pesticide residues by fast gas chromatography in combination with negative chemical ionization mass spectrometry.

    PubMed

    Húsková, Renáta; Matisová, Eva; Hrouzková, Svetlana; Svorc, Lubomír

    2009-08-28

    A combination of fast GC with narrow-bore column and bench top quadrupole mass spectrometer (MS) detector in negative chemical ionization (NCI) mode (with methane as reagent gas) is set up and utilized for the ultratrace analysis of 25 selected pesticides. The observed pesticides, belonging to the endocrine disrupting chemicals (EDCs), were from different chemical classes. A comparative study with electron impact (EI) ionization was also carried out (both techniques in selected ion monitoring (SIM) mode). The programmed temperature vaporizer (PTV) injector in solvent vent mode and narrow-bore column (15mx0.15mm I.D.x0.15microm film of 5% diphenyl 95% dimethylsiloxane stationary phase) were used for effective and fast separation. Heptachlor (HPT) as internal standard (I.S.) was applied for the comparison of results obtained from absolute and normalized peak areas. Non-fatty food matrices were investigated. Fruit (apple - matrix-matched standards; orange, strawberry, plum - real samples) and vegetable (lettuce - real sample) extracts were prepared by a quick and effective QuEChERS sample preparation technique. Very good results were obtained for the characterization of fast GC-NCI-MS method analysing EDCs pesticides. Analyte response was linear from 0.01 to 150microgkg(-1) with the R(2) values in the range from 0.9936 to 1.0000 (calculated from absolute peak areas) and from 0.9956 to 1.0000 (calculated from peak areas normalized to HPT). Instrument limits of detection (LODs) and quantification (LOQs) were found at pgmL(-1) level and for the majority of analytes were up to three orders of magnitude lower for NCI compared to EI mode. In both ionization modes, repeatability of measurements expressed as relative standard deviation (RSDs) was less than 10% which is in very good agreement with the criterion of European Union.

  6. Identifying Extraplanar Diffuse Ionized Gas in a Sample of MaNGA Galaxies

    NASA Astrophysics Data System (ADS)

    Hubbard, Ryan J.; Diamond-Stanic, Aleksandar M.; MaNGA Team

    2016-01-01

    The efficiency with which galaxies convert gas into stars is driven by the continuous cycle of accretion and feedback processes within the circumgalactic medium. Extraplanar diffuse ionized gas (eDIG) can provide insights into the tumultuous processes that govern the evolution of galactic disks because eDIG emission traces both inflowing and outflowing gas. With the help of state-of-the-art, spatially-resolved spectroscopy from MaNGA (Mapping Nearby Galaxies at Apache Point Observatory), we developed a computational method to identify eDIG based on the strength of and spatial extent of optical emission lines for a diverse sample of 550 nearby galaxies. This sample includes roughly half of the MaNGA galaxies that will become publicly available in summer 2016 as part of the Thirteenth Data Release of the Sloan Digital Sky Survey. We identified signatures of eDIG in 8% of the galaxies in this sample, and we found that these signatures are particularly common among galaxies with active star formation and inclination angles >45 degrees. Our analysis of the morphology, incidence, and kinematics of eDIG has important implications for current models of accretion and feedback processes that regulate star formation in galaxies. We acknowledge support from the Astrophysics REU program at the University of Wisconsin-Madison, the National Astronomy Consortium, and The Grainger Foundation.

  7. Accuracy of commercial blood gas analyzers for monitoring ionized calcium at low concentrations.

    PubMed

    D'Orazio, Paul; Visnick, Helen; Balasubramanian, Shankar

    2016-10-01

    Variable ionized calcium measurements in post filter blood samples during continuous renal replacement therapy (renal dialysis) using regional citrate anticoagulation (RCA) have been reported using commercial blood gas analyzers, resulting in analyzer-dependent differences in decisions regarding adjustment of citrate dose. We evaluated accuracy for measurement of iCa at low concentrations by 4 commercial blood gas analyzers using primary reference solutions formulated down to 0.15mmol/l iCa. Of the 4 analyzers tested, GEM Premier 4000 demonstrates acceptable accuracy for iCa measurement with a median deviation of -6.7% (-0.01mmol/l) at 0.15mmol/l, while other analyzers tested show increasingly positive biases from +40% (+0.06mmol/l) to +60% (+0.09mmol/l) relative to target. These relative differences are consistent with discordant results reported for measurement of iCa in blood during RCA. Interference from sodium with measured iCa and carryover from system rinse solution to sample are likely contributors to variability. We conclude the GEM Premier 4000 shows acceptable accuracy for measuring iCa at low concentrations required to control citrate dose during RCA. The method presented here may be used to test accuracy of any blood gas analyzer prior to use in clinical applications requiring measurement of iCa at low concentrations. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Determination of residual epichlorohydrin in sevelamer hydrochloride by static headspace gas chromatography with flame ionization detection.

    PubMed

    Karthikeyan, Kaliaperumal; Arularasu, Govindasamy T; Devaraj, Perumalsamy; Pillai, Karnam Chandrasekara

    2010-01-01

    A sensitive static headspace gas chromatographic method was developed and validated for the determination of residual epichlorohydrin (ECH) in sevelamer hydrochloride (SVH) drug substance. This method utilized a Phenomenex Zebron ZB-WAX GC column, helium as carrier gas with flame ionization detection. The critical experimental parameters, such as, headspace vial incubation time and incubation temperature were studied and optimized. The method was validated as per United States Pharmacopoeia (USP) and International Conference on Harmonization (ICH) guidelines in terms of detection limit (DL), quantitation limit (QL), linearity, precision, accuracy, specificity and robustness. A linear range from 0.30 to 10 Îg/mL was obtained with the coefficient of determination (r(2)) 0.999. The DL and QL of ECH were 0.09 Îg/mL and 0.30 Îg/mL, respectively. The recovery obtained for ECH was between 91.7 and 96.6%. Also, the specificity of the method was proved through gas chromatography mass spectrometry (GC-MS). This method was applied successfully to determine the content of residual ECH in SVH bulk drug.

  9. Determination of Residual Epichlorohydrin in Sevelamer Hydrochloride by Static Headspace Gas Chromatography with Flame Ionization Detection

    PubMed Central

    Karthikeyan, Kaliaperumal; Arularasu, Govindasamy T.; Devaraj, Perumalsamy; Pillai, Karnam Chandrasekara

    2010-01-01

    A sensitive static headspace gas chromatographic method was developed and validated for the determination of residual epichlorohydrin (ECH) in sevelamer hydrochloride (SVH) drug substance. This method utilized a Phenomenex Zebron ZB-WAX GC column, helium as carrier gas with flame ionization detection. The critical experimental parameters, such as, headspace vial incubation time and incubation temperature were studied and optimized. The method was validated as per United States Pharmacopoeia (USP) and International Conference on Harmonization (ICH) guidelines in terms of detection limit (DL), quantitation limit (QL), linearity, precision, accuracy, specificity and robustness. A linear range from 0.30 to 10 μg/mL was obtained with the coefficient of determination (r2) 0.999. The DL and QL of ECH were 0.09 μg/mL and 0.30 μg/mL, respectively. The recovery obtained for ECH was between 91.7 and 96.6%. Also, the specificity of the method was proved through gas chromatography mass spectrometry (GC-MS). This method was applied successfully to determine the content of residual ECH in SVH bulk drug. PMID:21179319

  10. A Desorbed Gas Molecular Ionization Mechanism for Arcing Onset in Solar Arrays Immersed in a Low-Density Plasma

    NASA Technical Reports Server (NTRS)

    Galofaro, J.; Vayner, B.; Ferguson, D.; Degroot, W.

    2002-01-01

    Previous experimental studies have hypothesized that the onset of Solar Array Arc (SAA) initiation in low-density space plasmas is caused by a desorbed gas molecular ionization mechanism. Indeed past investigations performed at the NASA Glenn Plasma Interaction Facility tend to not only support the desorbed gas molecular ionization mechanism, but have gone as far as identifying the crucial molecular species that must be present for molecular ion dominated process to occur. When electrical breakdown occurs at a triple junction site on a solar array panel, a quasi-neutral plasma cloud is ejected. Assuming the main component of the expelled plasma cloud by weight is due to water vapor, the fastest process available is due to HO molecules and OH(+) ions, or more succinctly, dissociative molecular-ion dominated recombination processes: H2O(+) + e(-) yields H* + OH*. Recently published spectroscopic observations of solar array arc spectra in ground tests have revealed the well-known molecular OH band (302 to 309nm), as well as the molecular SiH band (387nm peak), and the molecular CH band (432nm peak). Note that the OH band is observed in emission arcs where water vapor is present. Strong atomic lines were also observed for H(sub beta) at 486nm and H(sub alpha) at 656.3nm in prior ground testing. Independent supporting evidence of desorbed gas molecular ionization mechanisms also come from measurements of arc current pulse widths at different capacitances. We will revisit an earlier first order approximation demonstrating the dependence of arc current pulse widths on the square root of the capacitance. The simple arc current pulse width model will be then be used to estimate the temperature of the arc plasma (currently believed to be somewhere in the range of 3 to 5 eV). The current paper then seeks to extend the outlined work by including numerous vacuum chamber measurements obtained with a quadrupole mass spectrometer. A small solar array was mounted inside the vacuum

  11. Interrelated structures of the transport shock and collisional relaxation layer in a multitemperature, multilevel ionized gas

    NASA Technical Reports Server (NTRS)

    Vinolo, A. R.; Clarke, J. H.

    1973-01-01

    The gas dynamic structures of the transport shock and the downstream collisional relaxation layer are evaluated for partially ionized monatomic gases. Elastic and inelastic collisional nonequilibrium effects are taken into consideration. In the microscopic model of the atom, three electronic levels are accounted for. By using an asymptotic technique, the shock morphology is found on a continuum flow basis. This procedure gives two distinct layers in which the nonequilibrium effects to be considered are different. A transport shock appears as the inner solution to an outer collisional relaxation layer. The results show four main interesting points: (1) on structuring the transport shock, ionization and excitation rates must be included in the formulation, since the flow is not frozen with respect to the population of the different electronic levels; (2) an electron temperature precursor appears at the beginning of the transport shock; (3) the collisional layer is rationally reduced to quadrature for special initial conditions, which (4) are obtained from new Rankine-Hugoniot relations for the inner shock.

  12. Measurement of photon flux with a miniature gas ionization chamber in a Material Testing Reactor

    NASA Astrophysics Data System (ADS)

    Fourmentel, D.; Filliatre, P.; Villard, J. F.; Lyoussi, A.; Reynard-Carette, C.; Carcreff, H.

    2013-10-01

    Nuclear heating measurements in Material Testing Reactors (MTR) are crucial for the design of the experimental devices and the prediction of the temperature of the hosted samples. Nuclear heating in MTR materials (except fuel) is mainly due to the energy deposition by the photon flux. Therefore, the photon flux is a key input parameter for the computer codes which simulate nuclear heating and temperature reached by samples/devices under irradiation. In the Jules Horowitz MTR under construction at the CEA Cadarache, the maximal expected nuclear heating levels will be about 15 to 18 W g-1 and it will be necessary to assess this parameter with the best accuracy. An experiment was performed at the OSIRIS reactor to combine neutron flux, photon flux and nuclear heating measurements to improve the knowledge of the nuclear heating in MTR. There are few appropriate sensors for selective measurement of the photon flux in MTR even if studies and developments are ongoing. An experiment, called CARMEN-1, was conducted at the OSIRIS MTR and we used in particular a gas ionization chamber based on miniature fission chamber design to measure the photon flux. In this paper, we detail Monte-Carlo simulations to analyze the photon fluxes with ionization chamber measurements and we compare the photon flux calculations to the nuclear heating measurements. These results show a good accordance between photon flux measurements and nuclear heating measurement and allow improving the knowledge of these parameters.

  13. Interrelated structures of the transport shock and collisional relaxation layer in a multitemperature, multilevel ionized gas

    NASA Technical Reports Server (NTRS)

    Vinolo, A. R.; Clarke, J. H.

    1973-01-01

    The gas dynamic structures of the transport shock and the downstream collisional relaxation layer are evaluated for partially ionized monatomic gases. Elastic and inelastic collisional nonequilibrium effects are taken into consideration. In the microscopic model of the atom, three electronic levels are accounted for. By using an asymptotic technique, the shock morphology is found on a continuum flow basis. This procedure gives two distinct layers in which the nonequilibrium effects to be considered are different. A transport shock appears as the inner solution to an outer collisional relaxation layer. The results show four main interesting points: (1) on structuring the transport shock, ionization and excitation rates must be included in the formulation, since the flow is not frozen with respect to the population of the different electronic levels; (2) an electron temperature precursor appears at the beginning of the transport shock; (3) the collisional layer is rationally reduced to quadrature for special initial conditions, which (4) are obtained from new Rankine-Hugoniot relations for the inner shock.

  14. Measurement of the first Townsend ionization coefficient in a methane-based tissue-equivalent gas

    NASA Astrophysics Data System (ADS)

    Petri, A. R.; Gonçalves, J. A. C.; Mangiarotti, A.; Botelho, S.; Bueno, C. C.

    2017-03-01

    Tissue-equivalent gases (TEGs), often made of a hydrocarbon, nitrogen, and carbon dioxide, have been employed in microdosimetry for decades. However, data on the first Townsend ionization coefficient (α) in such mixtures are scarce, regardless of the chosen hydrocarbon. In this context, measurements of α in a methane-based tissue-equivalent gas (CH4 - 64.4%, CO2 - 32.4%, and N2 - 3.2%) were performed in a uniform field configuration for density-normalized electric fields (E/N) up to 290 Td. The setup adopted in our previous works was improved for operating at low pressures. The modifications introduced in the apparatus and the experimental technique were validated by comparing our results of the first Townsend ionization coefficient in nitrogen, carbon dioxide, and methane with those from the literature and Magboltz simulations. The behavior of α in the methane-based TEG was consistent with that observed for pure methane. All the experimental results are included in tabular form in the Supplementary material.

  15. The ionized gas in the CALIFA early-type galaxies. I. Mapping two representative cases: NGC 6762 and NGC 5966

    NASA Astrophysics Data System (ADS)

    Kehrig, C.; Monreal-Ibero, A.; Papaderos, P.; Vílchez, J. M.; Gomes, J. M.; Masegosa, J.; Sánchez, S. F.; Lehnert, M. D.; Cid Fernandes, R.; Bland-Hawthorn, J.; Bomans, D. J.; Marquez, I.; Mast, D.; Aguerri, J. A. L.; López-Sánchez, Á. R.; Marino, R. A.; Pasquali, A.; Perez, I.; Roth, M. M.; Sánchez-Blázquez, P.; Ziegler, B.

    2012-04-01

    As part of the ongoing CALIFA survey, we have conducted a thorough bidimensional analysis of the ionized gas in two E/S0 galaxies, NGC 6762 and NGC 5966, aiming to shed light on the nature of their warm ionized ISM. Specifically, we present optical (3745-7300 Å) integral field spectroscopy obtained with the PMAS/PPAK integral field spectrophotometer. Its wide field-of-view (1' × 1') covers the entire optical extent of each galaxy down to faint continuum surface brightnesses. To recover the nebular lines, we modeled and subtracted the underlying stellar continuum from the observed spectra using the STARLIGHT spectral synthesis code. The pure emission-line spectra were used to investigate the gas properties and determine the possible sources of ionization. We show the advantages of IFU data in interpreting the complex nature of the ionized gas in NGC 6762 and NGC 5966. In NGC 6762, the ionized gas and stellar emission display similar morphologies, while the emission line morphology is elongated in NGC 5966, spanning ~6 kpc, and is oriented roughly orthogonal to the major axis of the stellar continuum ellipsoid. Whereas gas and stars are kinematically aligned in NGC 6762, the gas is kinematically decoupled from the stars in NGC 5966. A decoupled rotating disk or an "ionization cone" are two possible interpretations of the elongated ionized gas structure in NGC 5966. The latter would be the first "ionization cone" of such a dimension detected within a weak emission-line galaxy. Both galaxies have weak emission-lines relative to the continuum[EW(Hα) ≲ 3 Å] and have very low excitation, log([Oiii]λ5007/Hβ) ≲ 0.5. Based on optical diagnostic ratios ([Oiii]λ5007/Hβ, [Nii]λ6584/Hα, [Sii]λ6717, 6731/Hα, [Oi]λ6300/Hα), both objects contain a LINER nucleus and an extended LINER-like gas emission. The emission line ratios do not vary significantly with radius or aperture, which indicates that the nebular properties are spatially homogeneous. The gas emission

  16. A new, sensitive, high resolution Raman detector based on ionization

    NASA Astrophysics Data System (ADS)

    Smith, B. W.; Omenetto, N.; Winefordner, J. D.

    1989-01-01

    A novel detection method for weak pulsed or cw Raman fluxes is described. The detector is based upon the production of Raman scatter with a tunable pulsed or cw dye laser, collecting a large fraction of the Raman scatter and transferring it efficiently into an ionization detector containing a metal (M) vapor, such as Li. The resonance ionization detector (RID) is simultaneously illuminated by a second dye laser. When the second laser is tuned to an excited state transition of the metal vapor M and when the first laser is at such a wavelength that the Raman scatter appears at the ground state absorption transition of the metal, then a current will be produced in the RID which is proportional to the Raman scatter intensity. Both the production and collection of this current can be made very efficient (approaching 100%) and should result in improved sensitivity compared to conventional dispersive or FT Raman techniques. The new approach should be much less sensitive to scatter, should have a spectral resolution better than 0.1 cm -1 and should allow Raman scatter measurements to be made at wavenumbers below 100 cm -1 and under certain conditions to 0.01 cm -1. The approach should be especially useful in highly scattering environments like Ag-sols in surface enhanced Raman and should be useful for detection of ultratrace levels of drugs and metabolites in biological fluids. The Raman-RID approach should also be useful for resonance Raman since laser scatter and molecular fluorescence should have minimal effects.

  17. Identification of volatiles by headspace gas chromatography with simultaneous flame ionization and mass spectrometric detection.

    PubMed

    Tiscione, Nicholas B; Yeatman, Dustin Tate; Shan, Xiaoqin; Kahl, Joseph H

    2013-10-01

    Volatiles are frequently abused as inhalants. The methods used for identification are generally nonspecific if analyzed concurrently with ethanol or require an additional analytical procedure that employs mass spectrometry. A previously published technique utilizing a capillary flow technology splitter to simultaneously quantitate and confirm ethyl alcohol by flame ionization and mass spectrometric detection after headspace sampling and gas chromatographic separation was evaluated for the detection of inhalants. Methanol, isopropanol, acetone, acetaldehyde, toluene, methyl ethyl ketone, isoamyl alcohol, isobutyl alcohol, n-butyl alcohol, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane (Norflurane, HFC-134a), chloroethane, trichlorofluoromethane (Freon®-11), dichlorodifluoromethane (Freon®-12), dichlorofluoromethane (Freon®-21), chlorodifluoromethane (Freon®-22) and 1,2-dichlorotetrafluoroethane (Freon®-114) were validated for qualitative identification by this method. The validation for qualitative identification included evaluation of matrix effects, sensitivity, carryover, specificity, repeatability and ruggedness/robustness.

  18. Determination of selected fatty acids in dried sweat spot using gas chromatography with flame ionization detection.

    PubMed

    Kanďár, Roman; Drábková, Petra; Andrlová, Lenka; Kostelník, Adam; Čegan, Alexander

    2016-11-01

    A method is described for the determination of fatty acids in dried sweat spot and plasma samples using gas chromatography with flame ionization detection. Plasma and dried sweat spot samples were obtained from a group of blood donors. The sweat was collected from each volunteer during exercise. Sweat was spotted onto collection paper containing butylated hydroxytoluene. Fatty acids were derivatized with acetyl chloride in methanol to form methyl esters of fatty acids. The fatty acids in dried sweat spot samples treated with butylated hydroxytoluene and stored at -20°C were stable for 3 months. Our results indicate that sweat contains, among fatty acids with short chain, also fatty acids with long chain and unsaturated fatty acids. Linear relationships between percentage content of selected fatty acids in dried sweat spot and plasma were observed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Dispersion of seed vapor and gas ionization in an MHD second stage combustor and channel

    NASA Astrophysics Data System (ADS)

    Chang, S. L.; Lottes, S. A.; Bouillard, J. X.

    An approach is introduced for the simulation of a magnetohydrodynamic system consisting of a second stage combustor, a convergent nozzle, and a channel. The simulation uses an Argonne integral combustion flow computer code and another Argonne channel computer code to predict flow, thermal and electric properties in the seed particle laden reacting flow in the system. The combustion code is a general hydrodynamics computer code for two-phase, two-dimensional, turbulent, and reacting flows, based on mass, momentum, and energy conservation laws for gaseous and condensed phases. The channel code is a multigrid three-dimensional computer code for compressible flow subject to magnetic and electric interactions. Results of this study suggests that (1) the processes of seed particle evaporation, seed vapor dispersion, and gas ionization in the reacting flow are critical to the evaluation of the downstream channel performance, and (2) particle size, loading, and inlet profile have strong effects on wall deposition and plasma temperature development.

  20. Self-detection of x-ray Fresnel transmissivity using photoelectron-induced gas ionization

    SciTech Connect

    Stoupin, Stanislav

    2016-01-25

    Electric response of an x-ray mirror enclosed in a gas flow ionization chamber was studied under the conditions of total external reflection for hard x-rays. It is shown that the electric response of the system as a function of the incidence angle is defined by x-ray Fresnel transmissivity and photon-electron attenuation properties of the mirror material. A simple interpretation of quantum yield of the system is presented. The approach could serve as a basis for non-invasive in situ diagnostics of hard x-ray optics, easy access to complementary x-ray transmissivity data in x-ray reflectivity experiments, and might also pave the way to advanced schemes for angle and energy resolving x-ray detectors.

  1. Self-detection of x-ray Fresnel transmissivity using photoelectron-induced gas ionization

    NASA Astrophysics Data System (ADS)

    Stoupin, Stanislav

    2016-01-01

    Electric response of an x-ray mirror enclosed in a gas flow ionization chamber was studied under the conditions of total external reflection for hard x-rays. It is shown that the electric response of the system as a function of the incidence angle is defined by x-ray Fresnel transmissivity and photon-electron attenuation properties of the mirror material. A simple interpretation of quantum yield of the system is presented. The approach could serve as a basis for non-invasive in situ diagnostics of hard x-ray optics, easy access to complementary x-ray transmissivity data in x-ray reflectivity experiments, and might also pave the way to advanced schemes for angle and energy resolving x-ray detectors.

  2. Accurate Structure Parameters for Tunneling Ionization Rates of Gas-Phase Linear Molecules

    NASA Astrophysics Data System (ADS)

    Zhao, Song-Feng; Li, Jian-Ke; Wang, Guo-Li; Li, Peng-Cheng; Zhou, Xiao-Xin

    2017-03-01

    In the molecular Ammosov-Delone-Krainov (MO-ADK) model of Tong et al. [Phys. Rev. A 66 (2002) 033402], the ionization rate depends on the structure parameters of the molecular orbital from which the electron is removed. We determine systematically and tabulate accurate structure parameters of the highest occupied molecular orbital (HOMO) for 123 gas-phase linear molecules by solving time-independent Schrödinger equation with B-spline functions and molecular potentials which are constructed numerically using the modified Leeuwen-Baerends (LBα) model. Supported by National Natural Science Foundation of China under Grant Nos. 11664035, 11674268, 11465016, 11364038, 11364039, the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No. 20116203120001 and the Basic Scientific Research Foundation for Institution of Higher Learning of Gansu Province

  3. Determination of ibogaine in plasma by gas chromatography--chemical ionization mass spectrometry.

    PubMed

    Ley, F R; Jeffcoat, A R; Thomas, B F

    1996-02-02

    Ibogaine is naturally occurring indole alkaloid that is currently being considered as a treatment medication for drug dependence. Although there have been a variety of investigations regarding the mechanisms of action and pharmacology of ibogaine, relatively little has been reported regarding quantitative methods. Because of the paucity of analytical methodologies, studies involving the pharmacokinetics and metabolism of ibogaine have also been limited. A method is described for the determination of ibogaine levels in plasma by gas chromatography -- methane chemical ionization mass spectrometry. [13C2H3]Ibogaine was synthesized and used as an internal standard to control for recovery during sample preparation. The assay requires one ml of plasma and is shown to be a selective and sensitive means of ibogaine quantitation.

  4. Dispersion of seed vapor and gas ionization in an MHD second stage combustor and channel

    SciTech Connect

    Chang, S.L.; Lottes, S.A.; Bouillard, J.X.

    1992-07-01

    An approach is introduced for the simulation of a magnetohydrodynamic system consisting of a second stage combustor, a convergent nozzle, and a channel. The simulation uses an Argonne integral combustion flow computer code and another Argonne channel computer code to predict flow, thermal and electric properties in the seed particle laden reacting flow in the system. The combustion code is a general hydrodynamics computer code for two-phase, two-dimensional, turbulent, and reacting flows, based on mass, momentum, and energy conservation laws for gaseous and condensed phases. The channel code is a multigrid three-dimensional computer code for compressible flow subject to magnetic and electric interactions. Results of this study suggests that (1) the processes of seed particle evaporation, seed vapor dispersion, and gas ionization in the reacting flow are critical to the evaluation of the downstream channel performance and (2) particle size, loading, and inlet profile have strong effects on wall deposition and plasma temperature development.

  5. Dispersion of seed vapor and gas ionization in an MHD second stage combustor and channel

    SciTech Connect

    Chang, S.L.; Lottes, S.A.; Bouillard, J.X.

    1992-01-01

    An approach is introduced for the simulation of a magnetohydrodynamic system consisting of a second stage combustor, a convergent nozzle, and a channel. The simulation uses an Argonne integral combustion flow computer code and another Argonne channel computer code to predict flow, thermal and electric properties in the seed particle laden reacting flow in the system. The combustion code is a general hydrodynamics computer code for two-phase, two-dimensional, turbulent, and reacting flows, based on mass, momentum, and energy conservation laws for gaseous and condensed phases. The channel code is a multigrid three-dimensional computer code for compressible flow subject to magnetic and electric interactions. Results of this study suggests that (1) the processes of seed particle evaporation, seed vapor dispersion, and gas ionization in the reacting flow are critical to the evaluation of the downstream channel performance and (2) particle size, loading, and inlet profile have strong effects on wall deposition and plasma temperature development.

  6. The Effect of the Argon Carrier Gas in the Multiphoton Dissociation-Ionization of Tetracene

    PubMed Central

    Poveda, Juan Carlos; Román, Alejandro San; Guerrero, Alfonso; Álvarez, Ignacio; Cisneros, Carmen

    2008-01-01

    The multiphoton dissociation-ionization of tetracene at 355 nm using 6.5 nanosecond laser pulses, with and without argon as a carrier gas (CG), has been studied and compared. Ion fragments were analyzed in a time-of-flight mass spectrometer and separated according to their mass-to-charge ratio (m/z). The results show that the dynamic of photodissociation at ∼1010 W cm−2 intensities is strongly influenced by the CG. The suppression of fragmentation channels primarily those relating to the formation of the CHm+ (m = 2, 4), C2H4+ and C5H4+2 ions. CH5+ and CH6+ were observed which have not been reported before in photodissociation tetracene experiments. PMID:19325732

  7. Ionized gas (plasma) delivery of reactive oxygen species (ROS) into artificial cells

    NASA Astrophysics Data System (ADS)

    Hong, Sung-Ha; Szili, Endre J.; Jenkins, A. Toby A.; Short, Robert D.

    2014-09-01

    This study was designed to enhance our understanding of how reactive oxygen species (ROS), generated ex situ by ionized gas (plasma), can affect the regulation of signalling processes within cells. A model system, comprising of a suspension of phospholipid vesicles (cell mimics) encapsulating a ROS reporter, was developed to study the plasma delivery of ROS into cells. For the first time it was shown that plasma unequivocally delivers ROS into cells over a sustained period and without compromising cell membrane integrity. An important consideration in cell and biological assays is the presence of serum, which significantly reduced the transfer efficiency of ROS into the vesicles. These results are key to understanding how plasma treatments can be tailored for specific medical or biotechnology applications. Further, the phospholipid vesicle ROS reporter system may find use in other studies involving the application of free radicals in biology and medicine.

  8. Rapid measurement of phytosterols in fortified food using gas chromatography with flame ionization detection.

    PubMed

    Duong, Samantha; Strobel, Norbert; Buddhadasa, Saman; Stockham, Katherine; Auldist, Martin; Wales, Bill; Orbell, John; Cran, Marlene

    2016-11-15

    A novel method for the measurement of total phytosterols in fortified food was developed and tested using gas chromatography with flame ionization detection. Unlike existing methods, this technique is capable of simultaneously extracting sterols during saponification thus significantly reducing extraction time and cost. The rapid method is suitable for sterol determination in a range of complex fortified foods including milk, cheese, fat spreads, oils and meat. The main enhancements of this new method include accuracy and precision, robustness, cost effectiveness and labour/time efficiencies. To achieve these advantages, quantification and the critical aspects of saponification were investigated and optimised. The final method demonstrated spiked recoveries in multiple matrices at 85-110% with a relative standard deviation of 1.9% and measurement uncertainty value of 10%. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Construction of a versatile high precision ambient ionization source for direct analysis and imaging.

    PubMed

    Sampson, Jason S; Hawkridge, Adam M; Muddiman, David C

    2008-10-01

    The design and construction of a high precision ambient ionization source matrix-assisted laser desorption electrospray ionization (MALDESI) are described in full detail, including a complete parts list. The computer controlled high precision motion control system and high repetition rate Explorer laser are demonstrated during MALDESI-FT-ICR analysis of peptides and proteins ranging from 1 to 17 kDa. The high stability ionization source platform described herein demonstrates both the advantages of the new MALDESI source and versatility for application to numerous desorption and ionization techniques.

  10. CONSTRAINING STELLAR FEEDBACK: SHOCK-IONIZED GAS IN NEARBY STARBURST GALAXIES

    SciTech Connect

    Hong, Sungryong; Calzetti, Daniela; Gallagher, John S. III; Martin, Crystal L.; Conselice, Christopher J.; Pellerin, Anne

    2013-11-01

    We investigate the properties of feedback-driven shocks in eight nearby starburst galaxies using narrow-band imaging data from the Hubble Space Telescope. We identify the shock-ionized component via the line diagnostic diagram [O III] (λ5007)/Hβ versus [S II] (λλ6716, 6731) (or [N II] (λ6583))/Hα, applied to resolved regions 3-15 pc in size. We divide our sample into three sub-samples: sub-solar, solar, and super-solar, for consistent shock measurements. For the sub-solar sub-sample, we derive three scaling relations: (1) L{sub shock}∝SFR{sup 0.62}, (2) L{sub shock}∝Σ{sub SFR,{sub HL}} {sup 0.92}, and (3) L{sub shock}/L{sub tot}∝(L{sub H} /L{sub ☉,{sub H}}){sup –0.65}, where L{sub shock} is the Hα luminosity from shock-ionized gas, Σ{sub SFR,{sub HL}} the star formation rate (SFR) per unit half-light area, L{sub tot} the total Hα luminosity, and L{sub H} /L{sub ☉,{sub H}} the absolute H-band luminosity from the Two Micron All Sky Survey normalized to solar luminosity. The other two sub-samples do not have enough number statistics, but appear to follow the first scaling relation. The energy recovered indicates that the shocks from stellar feedback in our sample galaxies are fully radiative. If the scaling relations are applicable in general to stellar feedback, our results are similar to those by Hopkins et al. for galactic superwinds. This similarity should, however, be taken with caution at this point, as the underlying physics that enables the transition from radiative shocks to gas outflows in galaxies is still poorly understood.

  11. Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Rondo, L.; Ehrhart, S.; Kürten, A.; Adamov, A.; Bianchi, F.; Breitenlechner, M.; Duplissy, J.; Franchin, A.; Dommen, J.; Donahue, N. M.; Dunne, E. M.; Flagan, R. C.; Hakala, J.; Hansel, A.; Keskinen, H.; Kim, J.; Jokinen, T.; Lehtipalo, K.; Leiminger, M.; Praplan, A.; Riccobono, F.; Rissanen, M. P.; Sarnela, N.; Schobesberger, S.; Simon, M.; Sipilä, M.; Smith, J. N.; Tomé, A.; Tröstl, J.; Tsagkogeorgas, G.; Vaattovaara, P.; Winkler, P. M.; Williamson, C.; Wimmer, D.; Baltensperger, U.; Kirkby, J.; Kulmala, M.; Petäjä, T.; Worsnop, D. R.; Curtius, J.

    2016-03-01

    Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI-APi-TOF (Chemical Ionization-Atmospheric Pressure interface-Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI-APi-TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4-H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self-contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit.

  12. Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry.

    PubMed

    Rondo, L; Ehrhart, S; Kürten, A; Adamov, A; Bianchi, F; Breitenlechner, M; Duplissy, J; Franchin, A; Dommen, J; Donahue, N M; Dunne, E M; Flagan, R C; Hakala, J; Hansel, A; Keskinen, H; Kim, J; Jokinen, T; Lehtipalo, K; Leiminger, M; Praplan, A; Riccobono, F; Rissanen, M P; Sarnela, N; Schobesberger, S; Simon, M; Sipilä, M; Smith, J N; Tomé, A; Tröstl, J; Tsagkogeorgas, G; Vaattovaara, P; Winkler, P M; Williamson, C; Wimmer, D; Baltensperger, U; Kirkby, J; Kulmala, M; Petäjä, T; Worsnop, D R; Curtius, J

    2016-03-27

    Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI-APi-TOF (Chemical Ionization-Atmospheric Pressure interface-Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI-APi-TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4-H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self-contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit.

  13. High-quality electron beams from beam-driven plasma accelerators by wakefield-induced ionization injection.

    PubMed

    Martinez de la Ossa, A; Grebenyuk, J; Mehrling, T; Schaper, L; Osterhoff, J

    2013-12-13

    We propose a new and simple strategy for controlled ionization-induced trapping of electrons in a beam-driven plasma accelerator. The presented method directly exploits electric wakefields to ionize electrons from a dopant gas and capture them into a well-defined volume of the accelerating and focusing wake phase, leading to high-quality witness bunches. This injection principle is explained by example of three-dimensional particle-in-cell calculations using the code OSIRIS. In these simulations a high-current-density electron-beam driver excites plasma waves in the blowout regime inside a fully ionized hydrogen plasma of density 5×10(17)cm-3. Within an embedded 100  μm long plasma column contaminated with neutral helium gas, the wakefields trigger ionization, trapping of a defined fraction of the released electrons, and subsequent acceleration. The hereby generated electron beam features a 1.5 kA peak current, 1.5  μm transverse normalized emittance, an uncorrelated energy spread of 0.3% on a GeV-energy scale, and few femtosecond bunch length.

  14. The Ionized Gas and Nuclear Environment in NGC 3783. IV. Variability and Modeling of the 900 Kilosecond Chandra Spectrum

    NASA Astrophysics Data System (ADS)

    Netzer, Hagai; Kaspi, Shai; Behar, Ehud; Brandt, W. N.; Chelouche, Doron; George, Ian M.; Crenshaw, D. Michael; Gabel, Jack R.; Hamann, Frederick W.; Kraemer, Steven B.; Kriss, Gerard A.; Nandra, Kirpal; Peterson, Bradley M.; Shields, Joseph C.; Turner, T. J.

    2003-12-01

    We present a detailed spectral analysis of the data obtained from NGC 3783 during the period 2000-2001 using Chandra. The data were split in various ways to look for time- and luminosity-dependent spectral variations. This analysis, along with the measured equivalent widths of a large number of X-ray lines and photoionization calculations, lead us to the following results and conclusions. (1) NGC 3783 fluctuated in luminosity by a factor of ~1.5 during individual observations (most of which were of 170 ks duration). These fluctuations were not associated with significant spectral variations. (2) On a longer timescale (20-120 days), we found the source to exhibit two very different spectral shapes. The main difference between these can be well-described by the appearance (in the ``high state'') and disappearance (in the ``low state'') of a spectral component that dominates the underlying continuum at the longest wavelengths. Contrary to the case in other objects, the spectral variations are not related to the brightening or the fading of the continuum at short wavelengths in any simple way. NGC 3783 seems to be the first active galactic nucleus (AGN) to show this unusual behavior. (3) The appearance of the soft continuum component is consistent with being the only spectral variation, and there is no need to invoke changes in the opacity of the absorbers lying along the line of sight. Indeed, we find that all the absorption lines that can be reliably measured have the same equivalent widths (within the observational uncertainties) during high and low states. (4) Photoionization modeling indicates that a combination of three ionized absorbers, each split into two kinematic components, can explain the strengths of almost all the absorption lines and bound-free edges. These three components span a large range of ionization and have total column of about 4×1022 cm-2. Moreover, all three components are thermally stable and seem to have the same gas pressure. Thus, all

  15. THE KINEMATICS AND IONIZATION OF NUCLEAR GAS CLOUDS IN CENTAURUS A

    SciTech Connect

    Bicknell, Geoffrey V.; Sutherland, Ralph S.; Neumayer, Nadine E-mail: Ralph.Sutherland@anu.edu.au

    2013-03-20

    Neumayer et al. established the existence of a blueshifted cloud in the core of Centaurus A, within a few parsecs of the nucleus and close to the radio jet. We propose that the cloud has been impacted by the jet, and that it is in the foreground of the jet, accounting for its blueshifted emission on the southern side of the nucleus. We consider both shock excitation and photoionization models for the excitation of the cloud. Shock models do not account for the [Si VI] and [Ca VIII] emission line fluxes. However, X-ray observations indicate a source of ionizing photons in the core of Centaurus A; photoionization by the inferred flux incident on the cloud can account for the fluxes in these lines relative to Brackett-{gamma}. The power-law slope of the ionizing continuum matches that inferred from synchrotron models of the X-rays. The logarithm of the ionization parameter is -1.9, typical of that in Seyfert galaxies and consistent with the value proposed for dusty ionized plasmas. The model cloud density depends upon the Lorentz factor of the blazar and the inclination of our line of sight to the jet axis. For acute inclinations, the inferred density is consistent with expected cloud densities. However, for moderate inclinations of the jet to the line of sight, high Lorentz factors imply cloud densities in excess of 10{sup 5} cm{sup -3} and very low filling factors, suggesting that models of the gamma-ray emission should incorporate jet Lorentz factors {approx}< 5.

  16. Producing highly charged ions without solvent using laserspray ionization: a total solvent-free analysis approach at atmospheric pressure.

    PubMed

    Wang, Beixi; Lietz, Christopher B; Inutan, Ellen D; Leach, Samantha M; Trimpin, Sarah

    2011-06-01

    First examples of highly charged ions in mass spectrometry (MS) produced from the solid state without using solvent during either sample preparation or mass measurement are reported. Matrix material, matrix/analyte homogenization time and frequency, atmospheric pressure (AP) to vacuum inlet temperature, and mass analyzer ion trap conditions are factors that influence the abundance of the highly charged ions created by laserspray ionization (LSI). LSI, like matrix-assisted laser desorption/ionization (MALDI), uses laser ablation of a matrix/analyte mixture from a surface to produce ions. Preparing the matrix/analyte sample without the use of solvent provides the ability to perform total solvent-free analysis (TSA) consisting of solvent-free ionization and solvent-free gas-phase separation using ion mobility spectrometry (IMS) MS. Peptides and small proteins such as non-β-amyloid components of Alzheimer's disease and bovine insulin are examples in which LSI and TSA were combined to produce multiply charged ions, similar to electrospray ionization, but without the use of solvent. Advantages using solvent-free LSI and IMS-MS include simplicity, rapid data acquisition, reduction of sample complexity, and the potential for an enhanced effective dynamic range. This is achieved by more inclusive ionization and improved separation of mixture components as a result of multiple charging.

  17. Development and validation of a gas chromatography-flame ionization detection method for quantifying sucrose in equine serum.

    PubMed

    Hewetson, Michael; Aaltonen, Kaisa; Tulamo, Riitta-Mari; Sankari, Satu

    2014-03-01

    A simple and accurate method for quantifying sucrose in equine serum that can be applied to sucrose permeability testing in the horse was developed and validated using gas chromatography with flame ionization detection. The assay provided an acceptable degree of linearity, accuracy, and precision at concentrations of sucrose as low as 2.34 μmol/l and as high as 20.45 μmol/l. Percentage recovery of sucrose from serum ranged from 89% to 102%; repeatability and intermediate precision (relative standard deviation) ranged from 3.6% to 6.7% and 4.1% to 9.3%, respectively. The limit of detection was 0.73 μmol/l. No interfering peaks were observed except lactose, which gave 2 peaks, one of which overlapped partially with sucrose. To evaluate the suitability of the method for quantifying sucrose in serum samples from horses with naturally occurring gastric ulceration, 10 horses with and without naturally occurring gastric ulceration were subjected to sucrose permeability testing. All horses demonstrated an increase in serum sucrose concentration over time following oral administration of sucrose; however, the increase from baseline was significant for horses with gastric ulceration at 45 min (P = 0.0082) and 90 min (P = 0.0082) when compared with healthy horses. It was concluded that gas chromatography with flame ionization detection is a valid method for quantifying sucrose in equine serum and can be applied directly to the analysis of sucrose in equine serum as part of a larger validation study aimed at developing a blood test for the diagnosis of gastric ulcers in horses.

  18. Simultaneous Determination of Cyanide and Thiocyanate in Plasma by Chemical Ionization Gas Chromatography Mass-Spectrometry (CI-GC-MS)

    DTIC Science & Technology

    2012-09-04

    ORIGINAL PAPER Simultaneous determination of cyanide and thiocyanate in plasma by chemical ionization gas chromatography mass-spectrometry (CI-GC-MS...chemical ioniza- tion gas chromatography-mass spectrometry was developed for the simultaneous determination of cyanide and thiocya- nate in plasma...Sample preparation for this analysis required essentially one-step by combining the reaction of cyanide and thiocyanate with pentafluorobenzyl bromide

  19. Plasma ionization frequency, edge-to-axis density ratio, and density on axis of a cylindrical gas discharge

    SciTech Connect

    Palacio Mizrahi, J. H.

    2014-06-15

    A rigorous derivation of expressions, starting from the governing equations, for the ionization frequency, edge-to-axis ratio of plasma density, plasma density at the axis, and radially averaged plasma density in a cylindrical gas discharge has been obtained. The derived expressions are simple and involve the relevant parameters of the discharge: Cylinder radius, axial current, and neutral gas pressure. The found expressions account for ion inertia, ion temperature, and changes in plasma ion collisionality.

  20. Determination of BROMATE AT PARTS-PER-TRILLION LEVELS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY WITH NEGATIVE CHEMICAL IONIZATION

    EPA Science Inventory

    The ozonation of bromide-containing source waters produces bromate as a class 2B carcinogenic disinfection by-product. The present work describes the determination of bromate by gas chromatography-negative chemical ionization mass spectrometry (GC-NCIMS) following a bromate react...

  1. Determination of BROMATE AT PARTS-PER-TRILLION LEVELS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY WITH NEGATIVE CHEMICAL IONIZATION

    EPA Science Inventory

    The ozonation of bromide-containing source waters produces bromate as a class 2B carcinogenic disinfection by-product. The present work describes the determination of bromate by gas chromatography-negative chemical ionization mass spectrometry (GC-NCIMS) following a bromate react...

  2. Direct gas-phase detection of nerve and blister warfare agents utilizing active capillary plasma ionization mass spectrometry.

    PubMed

    Wolf, J-C; Schaer, M; P Siegenthaler, P; Zenobi, R

    2015-01-01

    Ultrasensitive direct gas-phase detection of chemical warfare agents (CWAs) is demonstrated utilizing active capillary plasma ionization and triple quadrupole mass spectrometry (MS) instrumentation. Four G- agents, two V-agents and various blistering agents [including sulfur mustard (HD)] were detected directly in the gas phase with limits of detection in the low parts per trillion (ng m(-3)) range. The direct detection of HD was shown for dry carrier gas conditions, but signals vanished when humidity was present, indicating a possible direct detection of HD after sufficient gas phase pretreatment. The method provided sufficient sensitivity to monitor directly the investigated volatile CWAs way below their corresponding minimal effect dose, and in most cases even below the eight hours worker exposure concentration. In general, the ionization is very soft, with little to no in-source fragmentation. Especially for the G-agents, some dimer formation occurred at higher concentrations. This adds complexity, but also further selectivity, to the corresponding mass spectra. Our results show that the active capillary plasma ionization is a robust, sensitive, "plug and play" ambient ionization source suited (but not exclusively) to the very sensitive detection of CWAs. It has the potential to be used with portable MS instrumentation.

  3. Ionized Gas Kinematics in the Inner 2 pc of the Milky Way: A Spiral Wave in a Keplerian Disk

    NASA Astrophysics Data System (ADS)

    Lacy, John H.; Irons, W.

    2011-05-01

    Numerous studies have been made of the ionized gas distribution and kinematics in Sgr A West, at the center of the Milky Way. Most of these have modeled the arcs of ionic emission as tidally stretched streamers, with the gas flowing along the streamers. A different model was proposed by Lacy et al. (1991), who argued that the observations required nearly circular motions for much of the gas, rather than motions along the streamers. Several physical explanation were suggested for how such a wave pattern could occur. None of the explanations were very compelling. We present new observations of the [Ne II] (12.8um) emission from Sgr A West, with improved spectral and spatial resolution (4 km/s and 1 arcsec). We compare the observations with models assuming the gas moves along elliptical orbits and models in which it moves across the streamers on circular orbits. The data strongly favor the latter model for much of the ionized gas. We still have no satisfactory physical explanation for how the gas is organized or ionized along what appears to be spiral wave. This work was supported by NSF grant AST-0607312.

  4. Highly Elliptical Orbits for Arctic observations: Assessment of ionizing radiation

    NASA Astrophysics Data System (ADS)

    Trichtchenko, L. D.; Nikitina, L. V.; Trishchenko, A. P.; Garand, L.

    2014-12-01

    The ionizing radiation environment was analyzed for a variety of potential Highly Elliptical Orbits (HEOs) with orbital periods ranging from 6 h to 24 h suitable to continuously monitor the Arctic region. Several models available from the ESA Space Environment Information System (SPENVIS) online tool were employed, including the new-generation AE9/AP9 model for trapped radiation. Results showed that the Total Ionizing Dose (TID) has a well-pronounced local minimum for the 14-h orbit, which is nearly identical to the overall minimum observed for the longest orbital period (24 h). The thickness of slab aluminum shielding required to keep the annual TID below 10, 5 and 3.33 krad (i.e. 150, 75 and 50 krad for 15 years of mission duration) for a 14-h orbit is 2.1, 2.7 and 3.1 mm respectively. The 16-h orbit requires an additional 0.5 mm of aluminum to achieve the same results, while the 24-h orbit requires less shielding in the order of 0.2-0.3 mm. Comparison between the AE8/AP8 and AE9/AP9 models was conducted for all selected orbits. Results demonstrated that differences ranged from -70% to +170% depending on orbit geometry. The vulnerability to the Single Event Effect (SEE) was compared for all orbits by modeling the Linear Energy Transfer (LET) for long-term conditions and for the 5 min “worst case” scenario. The analysis showed no preference among orbits with periods longer than 15 h, and in order to keep the 14-h orbit at the same level, the shielding should be increased by ∼33% or approximately by 1 mm. To keep the Single Event Upset (SEU) rate produced by the “worst case” event at the same order of magnitude as for the “statistical” long-term case, the thickness of aluminum should be as high as 22 mm. The overall conclusion from a space environment point of view is that all HEO orbits with periods equal to or longer than 14 h can be regarded as good candidates for operational missions. Therefore, selection of orbit should be based on other criteria

  5. Three-dimensional modeling of ionized gas. I. Did very massive stars of different metallicities drive the second cosmic reionization?

    NASA Astrophysics Data System (ADS)

    Weber, J. A.; Pauldrach, A. W. A.; Knogl, J. S.; Hoffmann, T. L.

    2013-07-01

    surrounding gas on various scales. Results: As our tool can handle distributions of numerous radiative sources characterized by high resolution synthetic SEDs, and also yields occupation numbers of the required energy levels of the most important elements which are treated in non-LTE and are calculated consistently with the 3d radiative transfer, the ionization state of an inhomogeneous gaseous density structure can be calculated accurately. We further demonstrate that the increasing metallicity of the radiative sources in the transition from population III stars to population II stars has a strong impact on the hardness of the emitted spectrum, and hence on the reionization history of helium. Conclusions: A top-heavy stellar mass distribution characterized by VMSs forming in chemically evolved clusters of high core mass density may not only provide the progenitors of intermediate-mass and supermassive black holes (SMBHs), but also play an important role for the reionization of He ii. The number of VMSs required to reionize He ii by a redshift of z ~ 2.5 is astonishingly close to the number of VMSs required to explain galactic SMBHs if one assumes that these have been formed by mergers of smaller black holes.

  6. Evaluation of gas chromatography-atmospheric pressure chemical ionization-mass spectrometry as an alternative to gas chromatography-electron ionization-mass spectrometry: avocado fruit as example.

    PubMed

    Hurtado-Fernández, Elena; Pacchiarotta, Tiziana; Longueira-Suárez, Enrique; Mayboroda, Oleg A; Fernández-Gutiérrez, Alberto; Carrasco-Pancorbo, Alegría

    2013-10-25

    Although GC-APCI-MS was developed more than 40 years ago this coupling is still far from being a routine technique. One of the reasons explaining the limited use of GC-APCI so far is the lack of spectral database which facilitates the identification of the compounds under study. The first application of a very recently developed GC-APCI database to identify as many compounds as possible in a complex matrix such as avocado fruit is presented here. The results achieved by using this database has been checked against those obtained using traditional GC-EI-MS and a comparison of the MS signals observed in both ionization sources has been carried out. 100 compounds belonging to different chemical families were identified in the matrix under study. Considering the results of this study, the wide range of application (in terms of polarity and size of analytes) and the robustness of APCI as interface, the high quality of TOF spectra, and our library as a publicly available resource, GC-APCI-TOF MS is definitively a valuable addition to the "metabolomics toolbox". Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Diffuse Ionized Gas in the Magellanic System: Early Results from WHAM-South

    NASA Astrophysics Data System (ADS)

    Haffner, L. Matthew; Madsen, G. J.

    2011-01-01

    From its new vantage point at CTIO, the Wisconsin Hα Mapper is poised to explore the full distribution and kinematics of diffuse plasma in extended gaseous structures near the Magellanic Clouds. Shaped by the interaction between the Clouds and the Milky Way, the Bridge, Stream, and Leading Arm gas complexes have been studied extensively in 21 cm emission and optical/UV absorption. With spectral resolution of 12 km/s, WHAM is able to separate optical emission from these structures and brighter local gas near vLSR 0 km/s. Combined with its unprecedented sensitivity to the limit of atmospheric line confusion ( 10s of mR), we are embarking on a survey of the ionized component of the Magellanic System with WHAM. With observations of the southern component of our all-sky survey nearly completed, we have begun to examine some emission features toward the Magellanic System. Here we present a sample of several regions observed recently with WHAM in Hα. WHAM was built and continues to operate with ongoing support from NSF. The research presented here is currently funded by award AST-0607512 and an International Program Development Fund from the University of Sydney.

  8. Gas-phase pesticide measurement using iodide ionization time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Murschell, Trey; Fulgham, S. Ryan; Farmer, Delphine K.

    2017-06-01

    Volatilization and subsequent processing in the atmosphere are an important environmental pathway for the transport and chemical fate of pesticides. However, these processes remain a particularly poorly understood component of pesticide lifecycles due to analytical challenges in measuring pesticides in the atmosphere. Most pesticide measurements require long (hours to days) sampling times coupled with offline analysis, inhibiting observation of meteorologically driven events or investigation of rapid oxidation chemistry. Here, we present chemical ionization time-of-flight mass spectrometry with iodide reagent ions as a fast and sensitive measurement of four current-use pesticides. These semi-volatile pesticides were calibrated with injections of solutions onto a filter and subsequently volatilized to generate gas-phase analytes. Trifluralin and atrazine are detected as iodide-molecule adducts, while permethrin and metolachlor are detected as adducts between iodide and fragments of the parent analyte molecule. Limits of detection (1 s) are 0.37, 0.67, 0.56, and 1.1 µg m-3 for gas-phase trifluralin, metolachlor, atrazine, and permethrin, respectively. The sensitivities of trifluralin and metolachlor depend on relative humidity, changing as much as 70 and 59, respectively, as relative humidity of the sample air varies from 0 to 80 %. This measurement approach is thus appropriate for laboratory experiments and potentially near-source field measurements.

  9. Dust trap formation in a non-self-sustained discharge with external gas ionization

    SciTech Connect

    Filippov, A. V. Babichev, V. N.; Pal’, A. F.; Starostin, A. N.; Cherkovets, V. E.; Rerikh, V. K.; Taran, M. D.

    2015-11-15

    Results from numerical studies of a non-self-sustained gas discharge containing micrometer dust grains are presented. The non-self-sustained discharge (NSSD) was controlled by a stationary fast electron beam. The numerical model of an NSSD is based on the diffusion drift approximation for electrons and ions and self-consistently takes into account the influence of the dust component on the electron and ion densities. The dust component is described by the balance equation for the number of dust grains and the equation of motion for dust grains with allowance for the Stokes force, gravity force, and electric force in the cathode sheath. The interaction between dust grains is described in the self-consistent field approximation. The height of dust grain levitation over the cathode is determined and compared with experimental results. It is established that, at a given gas ionization rate and given applied voltage, there is a critical dust grain size above which the levitation condition in the cathode sheath cannot be satisfied. Simulations performed for the dust component consisting of dust grains of two different sizes shows that such grains levitate at different heights, i.e., size separation of dust drains levitating in the cathode sheath of an NSSD takes place.

  10. Development of a Mesoscale Pulsed Discharge Helium Ionization Detector for Portable Gas Chromatography.

    PubMed

    Manginell, Ronald P; Mowry, Curtis D; Pimentel, Adam S; Mangan, Michael A; Moorman, Matthew W; Sparks, Elizabeth S; Allen, Amy; Achyuthan, Komandoor E

    2015-01-01

    Miniaturization of gas chromatography (GC) instrumentation enables field detection of volatile organic compounds (VOCs) for chembio-applications such as clandestine human transport and disease diagnostics. We fabricated a mesoscale pulsed discharge helium ionization detector (micro-PDHID) for integrating with our previously described mini-GC hardware. Stainless steel electrodes fabricated by photochemical etching and electroforming facilitated rapid prototyping and enabled nesting of inter-electrode insulators for self-alignment of the detector core during assembly. The prototype was ∼10 cm(3) relative to >400 cm(3) of a commercial PDHID, but with a comparable time to sweep a VOC peak from the detector cell (170 ms and 127 ms, respectively). Electron trajectory modeling, gas flow rate, voltage bias, and GC outlet location were optimized for improving sensitivity. Despite 40-fold miniaturization, the micro-PDHID detected 18 ng of the human emanation, 3-methyl-2-hexenoic acid with <3-fold decrease in sensitivity relative to the commercial detector. The micro-PDHID was rugged and operated for 9 months without failure.

  11. Signature of superradiance from a nitrogen-gas plasma channel produced by strong-field ionization

    NASA Astrophysics Data System (ADS)

    Li, Guihua; Jing, Chenrui; Zeng, Bin; Xie, Hongqiang; Yao, Jinping; Chu, Wei; Ni, Jielei; Zhang, Haisu; Xu, Huailiang; Cheng, Ya; Xu, Zhizhan

    2014-03-01

    Recently, Yao et al. demonstrated the creation of coherent emissions in nitrogen gas with two-color (800 nm + 400 nm) ultrafast laser pulses [J. Yao, G. Li, C. Jing, B. Zeng, W. Chu, J. Ni, H. Zhang, H. Xie, C. Zhang, H. Li, H. Xu, S. L. Chin, Y. Cheng, and Z. Xu, New J. Phys. 15, 023046 (2013), 10.1088/1367-2630/15/2/023046]. Based on this two-color scheme, here we report on systematic investigation of temporal characteristics of the radiation emitted at 391 nm [N2+: B2Σu+(ν =0) -X2Σg+(ν =0)] by experimentally examining its temporal profiles with the increase of the plasma channel induced by the intense 800-nm femtosecond laser pulses at a nitrogen-gas pressure of ˜25 mbar. We reveal unexpected temporal profiles of the coherent emissions, which show significant superradiance signatures owing to the cooperation of an ensemble of excited N2+ molecules that are coherently radiating in phase. Our findings shed more light on the mechanisms behind the coherent laserlike emissions induced by strong-field ionization of molecules.

  12. A detailed analysis of the high-resolution X-ray spectra of NGC 3516: variability of the ionized absorbers

    SciTech Connect

    Huerta, E. M.; Krongold, Y.; Jimenez-Bailon, E.; Nicastro, F.; Mathur, S.; Longinotti, A. L.

    2014-09-20

    The 1.5 Seyfert galaxy NGC 3516 presents a strong time variability in X-rays. We re-analyzed the nine observations performed in 2006 October by XMM-Newton and Chandra in the 0.3 to 10 keV energy band. An acceptable model was found for the XMM-Newton data fitting the EPIC-PN and RGS spectra simultaneously; later, this model was successfully applied to the contemporary Chandra high-resolution data. The model consists of a continuum emission component (power law + blackbody) absorbed by four ionized components (warm absorbers), and 10 narrow emission lines. Three absorbing components are warm, producing features only in the soft X-ray band. The fourth ionization component produces Fe XXV and Fe XXVI in the hard-energy band. We study the time response of the absorbing components to the well-detected changes in the X-ray luminosity of this source and find that the two components with the lower ionization state show clear opacity changes consistent with gas close to photoionization equilibrium. These changes are supported by the models and by differences in the spectral features among the nine observations. On the other hand, the two components with higher ionization state do not seem to respond to continuum variations. The response time of the ionized absorbers allows us to constrain their electron density and location. We find that one component (with intermediate ionization) must be located within the obscuring torus at a distance 2.7 × 10{sup 17} cm from the central engine. This outflowing component likely originated in the accretion disk. The three remaining components are at distances larger than 10{sup 16}-10{sup 17} cm. Two of the absorbing components in the soft X-rays have similar outflow velocities and locations. These components may be in pressure equilibrium, forming a multi-phase medium, if the gas has metallicity larger than the solar one (≳ 5 Z {sub ☉}). We also search for variations in the covering factor of the ionized absorbers (although partial

  13. Discrepant post filter ionized calcium concentrations by common blood gas analyzers in CRRT using regional citrate anticoagulation.

    PubMed

    Schwarzer, Patrik; Kuhn, Sven-Olaf; Stracke, Sylvia; Gründling, Matthias; Knigge, Stephan; Selleng, Sixten; Helm, Maximilian; Friesecke, Sigrun; Abel, Peter; Kallner, Anders; Nauck, Matthias; Petersmann, Astrid

    2015-09-08

    Ionized calcium (iCa) concentration is often used in critical care and measured using blood gas analyzers at the point of care. Controlling and adjusting regional citrate anticoagulation (RCA) for continuous renal replacement therapy (CRRT) involves measuring the iCa concentration in two samples: systemic with physiological iCa concentrations and post filter samples with very low iCa concentrations. However, modern blood gas analyzers are optimized for physiological iCa concentrations which might make them less suitable for measuring low iCa in blood with a high concentration of citrate. We present results of iCa measurements from six different blood gas analyzers and the impact on clinical decisions based on the recommendations of the dialysis' device manufacturer. The iCa concentrations of systemic and post filter samples were measured using six distinct, frequently used blood gas analyzers. We obtained iCa results of 74 systemic and 84 post filter samples from patients undergoing RCA for CRRT at the University Medicine of Greifswald. The systemic samples showed concordant results on all analyzers with median iCa concentrations ranging from 1.07 to 1.16 mmol/L. The medians of iCa concentrations for post filter samples ranged from 0.21 to 0.50 mmol/L. Results of >70% of the post filter samples would lead to major differences in decisions regarding citrate flow depending on the instrument used. Measurements of iCa in post filter samples may give misleading information in monitoring the RCA. Recommendations of the dialysis manufacturer need to be revised. Meanwhile, little weight should be given to post filter iCa. Reference methods for low iCa in whole blood containing citrate should be established.

  14. POLYCYCLIC AROMATIC HYDROCARBONS, IONIZED GAS, AND MOLECULAR HYDROGEN IN BRIGHTEST CLUSTER GALAXIES OF COOL-CORE CLUSTERS OF GALAXIES

    SciTech Connect

    Donahue, Megan; Mark Voit, G.; Hoffer, Aaron; De Messieres, Genevieve E.; O'Connell, Robert W.; McNamara, Brian R.; Nulsen, Paul E. J. E-mail: voit@pa.msu.edu

    2011-05-01

    We present measurements of 5-25 {mu}m emission features of brightest cluster galaxies (BCGs) with strong optical emission lines in a sample of nine cool-core clusters of galaxies observed with the Infrared Spectrograph on board the Spitzer Space Telescope. These systems provide a view of dusty molecular gas and star formation, surrounded by dense, X-ray-emitting intracluster gas. Past work has shown that BCGs in cool-core clusters may host powerful radio sources, luminous optical emission-line systems, and excess UV, while BCGs in other clusters never show this activity. In this sample, we detect polycyclic aromatic hydrocarbons (PAHs), extremely luminous, rotationally excited molecular hydrogen line emission, forbidden line emission from ionized gas ([Ne II] and [Ne III]), and infrared continuum emission from warm dust and cool stars. We show here that these BCGs exhibit more luminous forbidden neon and H{sub 2} rotational line emission than star-forming galaxies with similar total infrared luminosities, as well as somewhat higher ratios of 70 {mu}m/24 {mu}m luminosities. Our analysis suggests that while star formation processes dominate the heating of the dust and PAHs, a heating process consistent with suprathermal electron heating from the hot gas, distinct from star formation, is heating the molecular gas and contributing to the heating of the ionized gas in the galaxies. The survival of PAHs and dust suggests that dusty gas is somehow shielded from significant interaction with the X-ray gas.

  15. Delivering Transmembrane Peptide Complexes to the Gas Phase Using Nanodiscs and Electrospray Ionization

    NASA Astrophysics Data System (ADS)

    Li, Jun; Richards, Michele R.; Kitova, Elena N.; Klassen, John S.

    2017-07-01

    The gas-phase conformations of dimers of the channel-forming membrane peptide gramicidin A (GA), produced from isobutanol or aqueous solutions of GA-containing nanodiscs (NDs), are investigated using electrospray ionization-ion mobility separation-mass spectrometry (ESI-IMS-MS) and molecular dynamics (MD) simulations. The IMS arrival times measured for (2GA + 2Na)2+ ions from isobutanol reveal three different conformations, with collision cross-sections (Ω) of 683 Å2 (conformation 1, C1), 708 Å2 (C2), and 737 Å2 (C3). The addition of NH4CH3CO2 produced (2GA + 2Na)2+ and (2GA + H + Na)2+ ions, with Ω similar to those of C1, C2, and C3, as well as (2GA + 2H)2+, (2GA + 2NH4)2+, and (2GA + H + NH4)2+ ions, which adopt a single conformation with a Ω similar to that of C2. These results suggest that the nature of the charging agents, imparted by the ESI process, can influence dimer conformation in the gas phase. Notably, the POPC NDs produced exclusively (2GA + 2NH4)2+ dimer ions; the DMPC NDs produced both (2GA + 2H)2+ and (2GA + 2NH4)2+ dimer ions. While the Ω of (2GA + 2H)2+ is similar to that of C2, the (2GA + 2NH4)2+ ions from NDs adopt a more compact structure, with a Ω of 656 Å2. It is proposed that this compact structure corresponds to the ion conducting single stranded head-to-head helical GA dimer. These findings highlight the potential of NDs, combined with ESI, for transferring transmembrane peptide complexes directly from lipid bilayers to the gas phase.

  16. Delivering Transmembrane Peptide Complexes to the Gas Phase Using Nanodiscs and Electrospray Ionization

    NASA Astrophysics Data System (ADS)

    Li, Jun; Richards, Michele R.; Kitova, Elena N.; Klassen, John S.

    2017-10-01

    The gas-phase conformations of dimers of the channel-forming membrane peptide gramicidin A (GA), produced from isobutanol or aqueous solutions of GA-containing nanodiscs (NDs), are investigated using electrospray ionization-ion mobility separation-mass spectrometry (ESI-IMS-MS) and molecular dynamics (MD) simulations. The IMS arrival times measured for (2GA + 2Na)2+ ions from isobutanol reveal three different conformations, with collision cross-sections (Ω) of 683 Å2 (conformation 1, C1), 708 Å2 (C2), and 737 Å2 (C3). The addition of NH4CH3CO2 produced (2GA + 2Na)2+ and (2GA + H + Na)2+ ions, with Ω similar to those of C1, C2, and C3, as well as (2GA + 2H)2+, (2GA + 2NH4)2+, and (2GA + H + NH4)2+ ions, which adopt a single conformation with a Ω similar to that of C2. These results suggest that the nature of the charging agents, imparted by the ESI process, can influence dimer conformation in the gas phase. Notably, the POPC NDs produced exclusively (2GA + 2NH4)2+ dimer ions; the DMPC NDs produced both (2GA + 2H)2+ and (2GA + 2NH4)2+ dimer ions. While the Ω of (2GA + 2H)2+ is similar to that of C2, the (2GA + 2NH4)2+ ions from NDs adopt a more compact structure, with a Ω of 656 Å2. It is proposed that this compact structure corresponds to the ion conducting single stranded head-to-head helical GA dimer. These findings highlight the potential of NDs, combined with ESI, for transferring transmembrane peptide complexes directly from lipid bilayers to the gas phase. [Figure not available: see fulltext.

  17. High Energy Gas Fracturing Test

    SciTech Connect

    Schulte, R.

    2001-02-27

    The Rocky Mountain Oilfield Testing Center (RMOTC) has recently completed two tests of a high-energy gas fracturing system being developed by Western Technologies of Crossville, Tennessee. The tests involved the use of two active wells located at the Naval Petroleum Reserve No. 3 (NPR-3), thirty-five miles north of Casper, Wyoming (See Figure 1). During the testing process the delivery and operational system was enhanced by RMOTC, Western Technologies, and commercial wireline subcontractors. RMOTC has assisted an industrial client in developing their technology for high energy gas fracturing to a commercial level. The modifications and improvements implemented during the technology testing process are instrumental in all field testing efforts at RMOTC. The importance of well selection can also be critical in demonstrating the success of the technology. To date, significant increases in well productivity have been clearly proven in well 63-TPX-10. Gross fluid production was initially raised by a factor of three. Final production rates increased by a factor of six with the use of a larger submersible pump. Well productivity (bbls of fluid per foot of drawdown) increased by a factor of 15 to 20. The above results assume that no mechanical damage has occurred to the casing or cast iron bridge plug which could allow well production from the Tensleep ''B'' sand. In the case of well 61-A-3, a six-fold increase in total fluid production was seen. Unfortunately, the increase is clouded by the water injection into the well that was necessary to have a positive fluid head on the propellant tool. No significant increase in oil production was seen. The tools which were retrieved from both 63-TPX-10 and 61-A-3 indicated a large amount of energy, similar to high gram perforating, had been expended downhole upon the formation face.

  18. Properties of the ionized gas in HH 202 - II. Results from echelle spectrophotometry with Ultraviolet Visual Echelle Spectrograph

    NASA Astrophysics Data System (ADS)

    Mesa-Delgado, A.; Esteban, C.; García-Rojas, J.; Luridiana, V.; Bautista, M.; Rodríguez, M.; López-Martín, L.; Peimbert, M.

    2009-05-01

    We present results of deep echelle spectrophotometry of the brightest knot of the Herbig-Haro object HH 202 in the Orion Nebula - HH 202-S - using the Ultraviolet Visual Echelle Spectrograph in the spectral range from 3100 to 10400 Å. The high spectral resolution of the observations has permitted to separate the component associated with the ambient gas from that associated with the gas flow. We derive electron densities and temperatures from different diagnostics for both components, as well as the chemical abundances of several ions and elements from collisionally excited lines, including the first determinations of Ca+ and Cr+ abundances in the Orion Nebula. We also calculate the He+, C2+, O+ and O2+ abundances from recombination lines. The difference between the O2+ abundances determined from collisionally excited and recombination lines - the so-called abundance discrepancy factor - is 0.35 and 0.11 dex for the shock and nebular components, respectively. Assuming that the abundance discrepancy is produced by spatial variations in the electron temperature, we derive values of the temperature fluctuation parameter, t2, of 0.050 and 0.016 for the shock and nebular components, respectively. Interestingly, we obtain almost coincident t2 values for both components from the analysis of the intensity ratios of HeI lines. We find significant departures from case B predictions in the Balmer and Paschen flux ratios of lines of high principal quantum number n. We analyse the ionization structure of HH 202-S, finding enough evidence to conclude that the flow of HH 202-S has compressed the ambient gas inside the nebula trapping the ionization front. We measure a strong increase of the total abundances of nickel and iron in the shock component, the abundance pattern and the results of photoionization models for both components are consistent with the partial destruction of dust after the passage of the shock wave in HH 202-S. Based on observations collected at the European

  19. [Gas chromatography with a Pulsed discharge helium ionization detector for measurement of molecular hydrogen(H2) in the atmosphere].

    PubMed

    Luan, Tian; Fang, Shuang-xi; Zhou, Ling-xi; Wang, Hong-yang; Zhang, Gen

    2015-01-01

    A high precision GC system with a pulsed discharge helium ionization detector was set up based on the commercial Agilent 7890A gas chromatography. The gas is identified by retention time and the concentration is calculated through the peak height. Detection limit of the system is about 1 x 10(-9) (mole fraction, the same as below). The standard deviation of 140 continuous injections with a standard cylinder( concentration is roughly 600 x 10(-9)) is better than 0.3 x 10(-9). Between 409.30 x 10(-9) and 867.74 x 10(-9) molecular hydrogen mole fractions and peak height have good linear response. By using two standards to quantify the air sample, the precision meets the background molecular hydrogen compatibility goal within the World Meteorological Organization/Global Atmosphere Watch (WMO/GAW) program. Atmospheric molecular hydrogen concentration at Guangzhou urban area was preliminarily measured by this method from January to November 2013. The results show that the atmospheric molecular hydrogen mole fraction varies from 450 x 10(-9) to 700 x 10(-9) during the observation period, with the lowest value at 14:00 (Beijing time, the same as below) and the peak value at 20:00. The seasonal variation of atmospheric hydrogen at Guangzhou area was similar with that of the same latitude stations in northern hemisphere.

  20. Multi-phase ionization dynamics of carbon thin film irradiated by high power short pulse laser

    NASA Astrophysics Data System (ADS)

    Kawahito, Daiki; Kishimoto, Yasuaki

    2017-10-01

    The ionization dynamics of a carbon thin film irradiated by a high power short pulse laser in the range of 1019-20 W/cm2 are studied using the extended particle-based integrated code (EPIC), which includes atomic and collisional processes. Two types of ionization dynamics exhibiting different spatio-temporal structures are found to predominantly regulate the process, and arise depending on the laser amplitude. The first is a fast convective propagation for charge states up to C4+, which keeps a steep ionization front. The velocity of the front is of the order of the speed of light. The front formation results from the localized longitudinal electrostatic field and associated field ionization, which in turn propagates inside the film. This convective propagation is triggered when the laser field becomes high enough that electron bunches accelerated by the laser ponderomotive force reach relativistic energies and penetrate inside the film across the surface. The second dynamics is a fast non-diffusive propagation of ionization showing a long plasma density scale length for C5+ and C6+. This process results predominantly from electron impact ionization by high energy electron bunches successively produced by the laser. These electron bunches also excite wake fields that propagate inside the film and contribute to ionizing the film to higher charge states, i.e., C5+ and C6+, especially near the front surface. The effect of field ionization loss, which sensitively influences the ionization dynamics in the relatively low laser power regime, is also discussed.

  1. Numerical models of steady-state and pulsating flows of self-ionizing gas in plasma accelerator channels

    NASA Astrophysics Data System (ADS)

    Brushlinskii, K. V.; Kozlov, A. N.; Konovalov, V. S.

    2015-08-01

    This paper continues the series of numerical investigations of self-ionizing gas flows in plasma accelerator channels with an azimuthal magnetic field. The mathematical model is based on the equations of dynamics of a three-component continuous medium consisting of atoms, ions, and electrons; the model is supplemented with the equation of ionization and recombination kinetics within the diffusion approximation with account for photoionization and photorecombination. It also takes into account heat exchange, which in this case is caused by radiative heat conductance. Upon a short history of the issue, the proposed model, numerical methods, and results for steady-state and pulsating flows are described.

  2. Cross Sections for Ionization of Rare Gas Excimers by Electron Impact and Atomic and Molecular Processes in Excimer Lasers.

    DTIC Science & Technology

    1980-03-01

    Theoretical cross sections for ionization of msetastable excimers - helium , neon, argon, krypton and zenon - and of metastable mercury are presented...AO-A086 698 GEORGIA INST OF TECH ATLANTA SCHOOL. OF PHYSICS FB20/5 CROSS SECTION1S FOR IONIZATION OF RARE GAS EXCIMERS By ELECTRON -- ETC(O) MAR 80 M...in Excimer Lasers. - -- 7 AUT 4OR(u) 8. CONTRACT OR GRANT NUMBER-) M. Raymond Flannery aW K. J./McCann . I F33615-78-C-20 128 9 PERFORMING

  3. High pressure synthesis gas fermentation

    SciTech Connect

    Not Available

    1991-01-01

    The purpose of this research project is to build and test a pressure fermentation system for the production of ethanol from synthesis gas. The fermenters, pumps, controls, and analytical system will be procured or fabricated and assembled in our laboratory. This system will then be used to determine the effects of high pressure on growth and ethanol production by clostridium ljungdahlii. The limits of cell concentration and mass transport relationships will be found in continuous stirred tank reactor and immobilized cell reactors. The minimum retention times and reactor volumes will be found for ethanol production in these reactors. Retention times of a few seconds are expected to result from these experiments. 2 figs., 2 tabs.

  4. Wavelength Scaling of High Harmonic Generation Close to the Multiphoton Ionization Regime

    NASA Astrophysics Data System (ADS)

    Lai, Chien-Jen; Cirmi, Giovanni; Hong, Kyung-Han; Moses, Jeffrey; Huang, Shu-Wei; Granados, Eduardo; Keathley, Phillip; Bhardwaj, Siddharth; Kärtner, Franz X.

    2013-08-01

    We study the wavelength scaling of high harmonic generation efficiency with visible driver wavelengths in the transition between the tunneling and the multiphoton ionization regimes where the Keldysh parameter is around unity. Our experiment shows a less dramatic wavelength scaling of efficiency than the conventional case for near- and mid-IR driver wavelengths, and it is well explained by a generalized three-step model for increased Keldysh parameters that employs complex ionization times in addition to the nonadiabatic ionization. The complex ionization time is critical to avoid the divergence when replacing the quasistatic ionization model by the more general nonadiabatic ionization model. Together, the two modifications present a consistent description of the influence of the atomic potential on the rescattering process in the intermediate Keldysh regime.

  5. High-angular-momentum states as population traps in multiphoton ionization

    NASA Astrophysics Data System (ADS)

    de Boer, M. P.; Noordam, L. D.; Muller, H. G.

    1993-01-01

    Resonant and nonresonant multiphoton ionization of xenon is studied using short, circularly polarized light pulses (100 fs, 597 nm, 22 TW/cm2). A pump-probe measurement shows that, although bound states are substantially populated, they do not enhance the ionization signal. The bound states do not ionize because their high angular momentum repels the wave functions from the nucleus. Ionization does occur through intermediate states in the continuum, in spite of a large energy mismatch, because these states have more energy and therefore suffer less from the centrifugal barrier.

  6. Development of thin gaseous ionization detectors for measurements of high-energy hadron beams

    NASA Astrophysics Data System (ADS)

    Lee, Kyong Sei; Hong, Byungsik; Lee, Kisoo; Park, Sung Keun; Yu, Jaehee; Kim, Sang Yeol

    2014-04-01

    Thin gaseous ionization detectors have been developed based on a current-integration mode for measurements of high-energy hadron beams. In the present detector R&D, two different types of prototype detectors with an active area of 16 × 16 cm2, each equipped with 256-signal processing channels, were manufactured and tested with 43-MeV protons provided by the MC50 proton cyclotron at the Korea Institute of Radiological and Medical Science (KIRAMS). The first one was equipped with a single gas electron multiplier (GEM), and the second one was a thin-plane ionization detector without the GEM foil loaded. The linearities of the detector responses for both detectors were examined for various proton-beam intensities. The quantitative accuracies for the channel-response data and for the total detector responses measured for 43-MeV protons were 0.4% and 0.34%, respectively. We conclude from the beam test that operating both types of detectors in the current-integration mode will allow quality measurements of dynamic-mode hadron beams to be performed with accuracies of better than 1%.

  7. High-rate axial-field ionization chamber for particle identification of radioactive beams

    NASA Astrophysics Data System (ADS)

    Vadas, J.; Singh, Varinderjit; Visser, G.; Alexander, A.; Hudan, S.; Huston, J.; Wiggins, B. B.; Chbihi, A.; Famiano, M.; Bischak, M. M.; deSouza, R. T.

    2016-11-01

    The design, construction and performance characteristics of a simple axial-field ionization chamber suitable for identifying ions in a radioactive beam are presented. Optimized for use with low-energy radioactive beams (< 5 MeV / A) the detector presents only three 0.5 μm/cm2 foils to the beam in addition to the detector gas. A fast charge sensitive amplifier (CSA) integrated into the detector design is also described. Coupling this fast CSA to the axial field ionization chamber produces an output pulse with a risetime of 60-70 ns and a fall time of 100 ns, making the detector capable of sustaining a relatively high rate and providing a time resolution of 6-8 ns. Tests with an α source establish the detector energy resolution as ∼ 8 % for an energy deposit of ∼3.5 MeV. The energy resolution with beams of 2.5 and 4.0 MeV/A 39K ions and the dependence of the energy resolution on beam intensity is measured. At an instantaneous rate of 3×105 ions/s the energy resolution has degraded to 14% with a pileup of 12%. The good energy resolution of this detector at rates up to 3×105 ions/s makes it an effective tool in the characterization of low-energy radioactive beams.

  8. The susceptibility of TaOx-based memristors to high dose rate ionizing radiation and total ionizing dose

    DOE PAGES

    McLain, Michael Lee; Sheridan, Timothy J.; Hjalmarson, Harold Paul; ...

    2014-11-11

    This paper investigates the effects of high dose rate ionizing radiation and total ionizing dose (TID) on tantalum oxide (TaOx) memristors. Transient data were obtained during the pulsed exposures for dose rates ranging from approximately 5.0 ×107 rad(Si)/s to 4.7 ×108 rad(Si)/s and for pulse widths ranging from 50 ns to 50 μs. The cumulative dose in these tests did not appear to impact the observed dose rate response. Static dose rate upset tests were also performed at a dose rate of ~3.0 ×108 rad(Si)/s. This is the first dose rate study on any type of memristive memory technology. Inmore » addition to assessing the tolerance of TaOx memristors to high dose rate ionizing radiation, we also evaluated their susceptibility to TID. The data indicate that it is possible for the devices to switch from a high resistance off-state to a low resistance on-state in both dose rate and TID environments. The observed radiation-induced switching is dependent on the irradiation conditions and bias configuration. Furthermore, the dose rate or ionizing dose level at which a device switches resistance states varies from device to device; the enhanced susceptibility observed in some devices is still under investigation. As a result, numerical simulations are used to qualitatively capture the observed transient radiation response and provide insight into the physics of the induced current/voltages.« less

  9. Exploring atmospheric photooxidation with a new Gas Chromatograph Time-of-Flight Chemical Ionization Mass Spectrometer (GC-ToF-CIMS)

    NASA Astrophysics Data System (ADS)

    Nölscher, A. C.; Allen, H. M.; Teng, A.; Crounse, J.; Wennberg, P. O.

    2015-12-01

    Atmospheric photooxidation is a fundamental process that effectively removes pollutants and greenhouse gases from the air we breathe. One way to explore these processes is to directly measure the stable intermediate oxidation products. Chemical Ionization Mass Spectrometry (CIMS) has proven to be a powerful tool to sensitively detect with high time resolution photooxidation products in the atmosphere such as hydroperoxides, acids, nitrates, and other oxygenated volatile organic compounds. Despite the potential to elucidate atmospheric photooxidation in detail, field observations of such compounds are sparse. Here we present the development of a new Gas Chromatograph Time-of-Flight Chemical Ionization Mass Spectrometer (GC-ToF-CIMS) for field deployment. Using low pressure gas chromatography and CF3O- ionization chemistry, the selective operation of a GC is combined with the sensitive, specific, and fast detection of a high-resolution ToF-CIMS. The combination of chromatographic separation and exact mass identification allows detecting isomer resolved photooxidation products. Direct measurements in the atmosphere of such isomer distributions are particularly interesting due to the broad range of their individual atmospheric lifetimes and impacts.

  10. IZI: Inferring the Gas Phase Metallicity (Z) and Ionization Parameter (q) of Ionized Nebulae Using Bayesian Statistics

    NASA Astrophysics Data System (ADS)

    Blanc, Guillermo A.; Kewley, Lisa; Vogt, Frédéric P. A.; Dopita, Michael A.

    2015-01-01

    We present a new method for inferring the metallicity (Z) and ionization parameter (q) of H II regions and star-forming galaxies using strong nebular emission lines (SELs). We use Bayesian inference to derive the joint and marginalized posterior probability density functions for Z and q given a set of observed line fluxes and an input photoionization model. Our approach allows the use of arbitrary sets of SELs and the inclusion of flux upper limits. The method provides a self-consistent way of determining the physical conditions of ionized nebulae that is not tied to the arbitrary choice of a particular SEL diagnostic and uses all the available information. Unlike theoretically calibrated SEL diagnostics, the method is flexible and not tied to a particular photoionization model. We describe our algorithm, validate it against other methods, and present a tool that implements it called IZI. Using a sample of nearby extragalactic H II regions, we assess the performance of commonly used SEL abundance diagnostics. We also use a sample of 22 local H II regions having both direct and recombination line (RL) oxygen abundance measurements in the literature to study discrepancies in the abundance scale between different methods. We find that oxygen abundances derived through Bayesian inference using currently available photoionization models in the literature can be in good (~30%) agreement with RL abundances, although some models perform significantly better than others. We also confirm that abundances measured using the direct method are typically ~0.2 dex lower than both RL and photoionization-model-based abundances.

  11. IZI: INFERRING THE GAS PHASE METALLICITY (Z) AND IONIZATION PARAMETER (q) OF IONIZED NEBULAE USING BAYESIAN STATISTICS

    SciTech Connect

    Blanc, Guillermo A.; Kewley, Lisa; Vogt, Frédéric P. A.; Dopita, Michael A.

    2015-01-10

    We present a new method for inferring the metallicity (Z) and ionization parameter (q) of H II regions and star-forming galaxies using strong nebular emission lines (SELs). We use Bayesian inference to derive the joint and marginalized posterior probability density functions for Z and q given a set of observed line fluxes and an input photoionization model. Our approach allows the use of arbitrary sets of SELs and the inclusion of flux upper limits. The method provides a self-consistent way of determining the physical conditions of ionized nebulae that is not tied to the arbitrary choice of a particular SEL diagnostic and uses all the available information. Unlike theoretically calibrated SEL diagnostics, the method is flexible and not tied to a particular photoionization model. We describe our algorithm, validate it against other methods, and present a tool that implements it called IZI. Using a sample of nearby extragalactic H II regions, we assess the performance of commonly used SEL abundance diagnostics. We also use a sample of 22 local H II regions having both direct and recombination line (RL) oxygen abundance measurements in the literature to study discrepancies in the abundance scale between different methods. We find that oxygen abundances derived through Bayesian inference using currently available photoionization models in the literature can be in good (∼30%) agreement with RL abundances, although some models perform significantly better than others. We also confirm that abundances measured using the direct method are typically ∼0.2 dex lower than both RL and photoionization-model-based abundances.

  12. High potential recovery -- Gas repressurization

    SciTech Connect

    Madden, M.P.

    1998-05-01

    The objective of this project was to demonstrate that small independent oil producers can use existing gas injection technologies, scaled to their operations, to repressurize petroleum reservoirs and increase their economic oil production. This report gives background information for gas repressurization technologies, the results of workshops held to inform small independent producers about gas repressurization, and the results of four gas repressurization field demonstration projects. Much of the material in this report is based on annual reports (BDM-Oklahoma 1995, BDM-Oklahoma 1996, BDM-Oklahoma 1997), a report describing the results of the workshops (Olsen 1995), and the four final reports for the field demonstration projects which are reproduced in the Appendix. This project was designed to demonstrate that repressurization of reservoirs with gas (natural gas, enriched gas, nitrogen, flue gas, or air) can be used by small independent operators in selected reservoirs to increase production and/or decrease premature abandonment of the resource. The project excluded carbon dioxide because of other DOE-sponsored projects that address carbon dioxide processes directly. Two of the demonstration projects, one using flue gas and the other involving natural gas from a deeper coal zone, were both technical and economic successes. The two major lessons learned from the projects are the importance of (1) adequate infrastructure (piping, wells, compressors, etc.) and (2) adequate planning including testing compatibility between injected gases and fluids, and reservoir gases, fluids, and rocks.

  13. Gas-Phase Stability of Negatively Charged Organophosphate Metabolites Produced by Electrospray Ionization and Matrix-Assisted Laser Desorption/Ionization

    NASA Astrophysics Data System (ADS)

    Asakawa, Daiki; Mizuno, Hajime; Toyo'oka, Toshimasa

    2017-09-01

    The formation mechanisms of singly and multiply charged organophosphate metabolites by electrospray ionization (ESI) and their gas phase stabilities were investigated. Metabolites containing multiple phosphate groups, such as adenosine 5'-diphosphate (ADP), adenosine 5'-triphosphate (ATP), and D-myo-inositol-1,4,5-triphosphate (IP3) were observed as doubly deprotonated ions by negative-ion ESI mass spectrometry. Organophosphates with multiple negative charges were found to be unstable and often underwent loss of PO3 -, although singly deprotonated analytes were stable. The presence of fragments due to the loss of PO3 - in the negative-ion ESI mass spectra could result in the misinterpretation of analytical results. In contrast to ESI, matrix-assisted laser desorption ionization (MALDI) produced singly charged organophosphate metabolites with no associated fragmentation, since the singly charged anions are stable. The stability of an organophosphate metabolite in the gas phase strongly depends on its charge state. The fragmentations of multiply charged organophosphates were also investigated in detail through density functional theory calculations. [Figure not available: see fulltext.

  14. Hubble Space Telescope/WFPC2 and VLA Observations of the Ionized Gas in the Dwarf Starburst Galaxy NGC 4214

    NASA Astrophysics Data System (ADS)

    MacKenty, John W.; Maíz-Apellániz, Jesús; Pickens, Christopher E.; Norman, Colin A.; Walborn, Nolan R.

    2000-12-01

    We present new Hα and [O III] λ5007 narrowband images of the starbursting dwarf galaxy NGC 4214, obtained with the Wide Field and Planetary Camera (WFPC2) on board the Hubble Space Telescope (HST), together with VLA observations of the same galaxy. The HST images resolve features down to physical scales of 2-5 pc, revealing several young (<10 Myr) star-forming complexes of various ionized gas morphologies (compact knots, complete or fragmentary shells) and sizes (~10-200 pc). Our results are consistent with a uniform set of evolutionary trends: The youngest, smaller, filled regions that presumably are those just emerging from dense star-forming clouds tend to be of high excitation and are highly obscured. Evolved, larger shell-like regions have lower excitation and are less extincted owing to the action of stellar winds and supernovae. In at least one case we find evidence for induced star formation, which has led to a two-stage starburst. Age estimates based on W(Hα) measurements do not agree with those inferred from wind-driven shell models of expanding H II regions. The most likely explanation for this effect is the existence of an ~2 Myr delay in the formation of superbubbles caused by the pressure exerted by the high-density medium in which massive stars are born. We report the detection of a supernova remnant embedded in one of the two large H II complexes of NGC 4214. The dust in NGC 4214 is not located in a foreground screen but is physically associated with the warm ionized gas. Based on observations with the NASA/ESA Hubble Space Telescope and the NRAO Very Large Array. The HST observations were obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS5-26555. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  15. Observations of columnal recombination in the ionization tracks of energetic heavy nuclei in an argon-methane gas mixture

    NASA Technical Reports Server (NTRS)

    Wiedenbeck, Mark E.

    1990-01-01

    Measurements of ionization signals resulting from the passage of energetic heavy nuclei through a gas mixture consisting of 95 mol percent Ar plus 5 mol percent CH4, at an absolute pressure of 3 atm are presented. The measurements take place under a uniform electric field perpendicular to the ionization track. The signals were compared to the calculated energy losses, with an assumption of proportionality between energy loss rate and ionization rate. Significant deviations from proportionality are found for energy loss rate grater than about 3000 MeV sq cm/g, while fractional deviations are found to be proportional to the energy loss rate (dE/dx) exp m, where m is equal to about two. These results are attributed to the columnal recombination.

  16. Observations of columnal recombination in the ionization tracks of energetic heavy nuclei in an argon-methane gas mixture

    NASA Technical Reports Server (NTRS)

    Wiedenbeck, Mark E.

    1990-01-01

    Measurements of ionization signals resulting from the passage of energetic heavy nuclei through a gas mixture consisting of 95 mol percent Ar plus 5 mol percent CH4, at an absolute pressure of 3 atm are presented. The measurements take place under a uniform electric field perpendicular to the ionization track. The signals were compared to the calculated energy losses, with an assumption of proportionality between energy loss rate and ionization rate. Significant deviations from proportionality are found for energy loss rate grater than about 3000 MeV sq cm/g, while fractional deviations are found to be proportional to the energy loss rate (dE/dx) exp m, where m is equal to about two. These results are attributed to the columnal recombination.

  17. Self-injection and acceleration of electrons during ionization of gas atoms by a short laser pulse

    SciTech Connect

    Singh, K.P.

    2006-04-15

    Using a relativistic three-dimensional single-particle code, acceleration of electrons created during the ionization of nitrogen and oxygen gas atoms by a laser pulse has been studied. Barrier suppression ionization model has been used to calculate ionization time of the bound electrons. The energy gained by the electrons peaks for an optimum value of laser spot size. The electrons created near the tail do not gain sufficient energy for a long duration laser pulse. The electrons created at the tail of pulse escape before fully interacting with the trailing part of the pulse for a short duration laser pulse, which causes electrons to retain sufficient energy. If a suitable frequency chirp is introduced then energy of the electrons created at the tail of the pulse further increases.

  18. Supercritical carbon dioxide extraction of electrolyte from spent lithium ion batteries and its characterization by gas chromatography with chemical ionization

    NASA Astrophysics Data System (ADS)

    Mönnighoff, Xaver; Friesen, Alex; Konersmann, Benedikt; Horsthemke, Fabian; Grützke, Martin; Winter, Martin; Nowak, Sascha

    2017-06-01

    The aging products of the electrolyte from a commercially available state-of-the-art 18650-type cell were investigated. During long term cycling a huge difference in their performance and lifetime at different temperatures was observed. By interpretation of a strong capacity fading of cells cycled at 20 °C compared to cells cycled at 45 °C a temperature depending aging mechanism was determined. To investigate the influence of the electrolyte on this fading, the electrolyte was extracted by supercritical fluid extraction (SFE) and then analyzed by gas chromatography (GC) with electron impact (EI) ionization and mass selective detection. To obtain more information with regard to the identification of unknown decomposition products further analysis with positive chemical ionization (PCI) and negative chemical ionization (NCI) was performed. 17 different volatile organic aging products were detected and identified. So far, seven of them were not yet known in literature and several formation pathways were postulated taking previously published literature into account.

  19. Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry

    PubMed Central

    Ehrhart, S.; Kürten, A.; Adamov, A.; Bianchi, F.; Breitenlechner, M.; Duplissy, J.; Franchin, A.; Dommen, J.; Donahue, N. M.; Dunne, E. M.; Flagan, R. C.; Hakala, J.; Hansel, A.; Keskinen, H.; Kim, J.; Jokinen, T.; Lehtipalo, K.; Leiminger, M.; Praplan, A.; Riccobono, F.; Rissanen, M. P.; Sarnela, N.; Schobesberger, S.; Simon, M.; Sipilä, M.; Smith, J. N.; Tomé, A.; Tröstl, J.; Tsagkogeorgas, G.; Vaattovaara, P.; Winkler, P. M.; Williamson, C.; Wimmer, D.; Baltensperger, U.; Kirkby, J.; Kulmala, M.; Petäjä, T.; Worsnop, D. R.; Curtius, J.

    2016-01-01

    Abstract Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI‐APi‐TOF (Chemical Ionization‐Atmospheric Pressure interface‐Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI‐APi‐TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4‐H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self‐contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit. PMID:27610289

  20. Testing a Dynamical Equilibrium Model of the Extraplanar Diffuse Ionized Gas in NGC 891

    NASA Astrophysics Data System (ADS)

    Boettcher, Erin; Zweibel, Ellen G.; Gallagher, J. S., III; Benjamin, Robert A.

    2016-12-01

    The observed scale heights of extraplanar diffuse ionized gas (eDIG) layers exceed their thermal scale heights by a factor of a few in the Milky Way and other nearby edge-on disk galaxies. Here, we test a dynamical equilibrium model of the eDIG layer in NGC 891, where we ask whether the thermal, turbulent, magnetic field, and cosmic-ray pressure gradients are sufficient to support the layer. In optical emission-line spectroscopy from the SparsePak integral field unit on the WIYN 3.5 m telescope, the Hα emission in position-velocity space suggests that the eDIG is found in a ring between galactocentric radii of {R}\\min ≤slant R≤slant 8 {kpc}, where {R}\\min ≥slant 2 {kpc}. We find that the thermal ({σ }{th}=11 km s-1) and turbulent ({σ }{turb}=25 km s-1) velocity dispersions are insufficient to satisfy the hydrostatic equilibrium equation given an exponential electron scale height of {h}z=1.0 {kpc}. Using a literature analysis of radio continuum observations from the CHANG-ES survey, we demonstrate that the magnetic field and cosmic-ray pressure gradients are sufficient to stably support the gas at R≥slant 8 kpc if the cosmic rays are sufficiently coupled to the system ({γ }{cr}=1.45). Thus, a stable dynamical equilibrium model is viable only if the eDIG is found in a thin ring around R = 8 kpc, and nonequilibrium models such as a galactic fountain flow are of interest for further study.

  1. Ethanol analysis by headspace gas chromatography with simultaneous flame-ionization and mass spectrometry detection.

    PubMed

    Tiscione, Nicholas B; Alford, Ilene; Yeatman, Dustin Tate; Shan, Xiaoqin

    2011-09-01

    Ethanol is the most frequently identified compound in forensic toxicology. Although confirmation involving mass spectrometry is desirable, relatively few methods have been published to date. A novel technique utilizing a Dean's Switch to simultaneously quantitate and confirm ethyl alcohol by flame-ionization (FID) and mass spectrometric (MS) detection after headspace sampling and gas chromatographic separation is presented. Using 100 μL of sample, the limits of detection and quantitation were 0.005 and 0.010 g/dL, respectively. The zero-order linear range (r(2) > 0.990) was determined to span the concentrations of 0.010 to 1.000 g/dL. The coefficient of variation of replicate analyses was less than 3.1%. Quantitative accuracy was within ±8%, ±6%, ±3%, and ±1.5% at concentrations of 0.010, 0.025, 0.080, and 0.300 g/dL, respectively. In addition, 1,1-difluoroethane was validated for qualitative identification by this method. The validated FID-MS method provides a procedure for the quantitation of ethyl alcohol in blood by FID with simultaneous confirmation by MS and can also be utilized as an identification method for inhalants such as 1,1-difluoroethane.

  2. Hα and [SII] Emission from Warm Ionized Gas in the Scutum-Centaurus Arm

    NASA Astrophysics Data System (ADS)

    Hill, Alex S.; Benjamin, Robert A.; Haffner, L. Matthew; Gostisha, Martin C.; Barger, Kathleen A.

    2014-06-01

    We present Wisconsin H-Alpha Mapper [SII] λ6716 and Hα spectroscopic maps of the warm ionized medium (WIM) in the Scutum-Centaurus Arm at Galactic longitudes 310° < l < 345°. Using extinction-corrected Hα intensities (I_{{H} \\alpha }^c), we measure an exponential scale height of electron density squared in the arm of H_{n_e^2}= 0.30 \\, {kpc} (assuming a distance of 3.5 kpc), intermediate between that observed in the inner Galaxy and in the Perseus Arm. The [S II]/Hα line ratio is enhanced at large |z| and in sightlines with faint I_{{H} \\alpha }^c. We find that the [S II]/Hα line ratio has a power-law relationship with I_{{H} \\alpha }^c from a value of ≈1.0 at I_{{H} \\alpha }^c< 0.2 \\, {R} (Rayleighs) to a value of ≈0.08 at I_{{H} \\alpha }^c\\gtrsim 100 \\, {R}. The line ratio is better correlated with Hα intensity than with height above the plane, indicating that the physical conditions within the WIM vary systematically with electron density. We argue that the variation of the line ratio with height is a consequence of the decrease of electron density with height. Our results reinforce the well-established picture in which the diffuse Hα emission is due primarily to emission from in situ photoionized gas, with scattered light only a minor contributor.

  3. Molecular, atomic, and ionized gas in the NGC 6334 star forming region

    NASA Technical Reports Server (NTRS)

    Kraemer, K. E.; Jackson, J. M.; Paglione, T. A. D.; Lane, A. P.

    1995-01-01

    NGC 6334 is a nearby (1.7 kpc) giant molecular cloud which contains at least 7 distinct sites of massive star formation. Using the Far-infrared Imaging Fabry-Perot Interferometer (FIFI) on the Kuiper Airborne Observatory we have imaged this region in the FIR fine structure lines of O(0) and C(+). The line intensity ratios are compared with the predicted line ratios from the PDR models of Wolfire, Tielens and Hollenbach (1990) (hereafter WTH) to determine the gas density and UV field strength. The (O I) 63 mu m/ 145 mu m intensity ratio is at least a factor of 10 lower than predicted. We suggest that self-absorption by cooler foreground material suppresses the (O I) 63 mu m line. We have also mapped CO J = 2 to 1 emission with the Caltech Submillimeter Observatory (CSO). In general, we find an anticorrelation of (C II) and CO emission. Particularly striking is a (C II) peak which is not associated with any CO, FIR or radio continuum source. Consequently, there is no local source of hard UV radiation. Either (1) the (C II) peak is illuminated by a cluster of embedded B stars, which radiate enough soft UV photons to ionize carbon, or (2) the (C II) peak is illuminated by a distant O star.

  4. Serum total testosterone: immunoassay compared with negative chemical ionization gas chromatography-mass spectrometry.

    PubMed

    Fitzgerald, R L; Herold, D A

    1996-05-01

    We have developed an electron capture negative chemical ionization gas chromatography-mass spectrometry (GC-MS) procedure to quantify serum testosterone in the clinically relevant range 0.69-69.3 nmol/L and used this procedure to assess Ciba Corning Diagnostics ACS:180 testosterone immunoassay. The GC-MS method involves liquid-liquid extraction of serum samples and synthesis of a pentafluorobenzyloxime/silyl ether derivative of testosterone with excellent chromatographic and electron capturing properties. The ACS testosterone assay is the first fully automated nonradioactive testosterone immunoassay approved by the US Food and Drug Administration. Patients' specimens (101, 57 males, 44 females) were analyzed by both techniques. A plot of the GC-MS (x) vs ACS (y) testosterone concentrations for men was linear (y = 1.07x + 0.19 nmol/L), showing excellent correlation (r2 = 0.98) between the two assays. Agreement of the two assays for female specimens was poor (y = 0.72x + 1.2 nmol/L), with a poor correlation (r2 = 0.31).

  5. Micro-flame ionization detector with a novel structure for portable gas chromatograph.

    PubMed

    Wang, Jianwei; Wang, Hua; Duan, Chunfeng; Guan, Yafeng

    2010-08-15

    A micro-flame ionization detector (micro-FID) for portable gas chromatograph (GC) based on conventional mechanical fabrication techniques was developed and evaluated. Structure was redesigned and dimensions were optimized for best performance. Air is introduced from upper part of the detector, flowing downwards into the burning chamber along a narrow round gap between the collection electrode and the inner wall of the detector body, forming a uniform flow field around the burning jet. The lowest detection limit of the mu-FID was 5x10(-13)g/s for n-decane, with a linear response range of five orders of magnitude. The consumption of gases is only 10 ml/min for hydrogen, and 120 ml/min for air, that is about 1/3 of the gases required for conventional FIDs. A comparative study between the micro-FID and commercial FID was also performed that proved the advantages of the micro-FID. The micro-FID is simple in structure, low heating power, and low consumption of gases that not only decrease the cost of running, but also increase the portability of GC for filed applications. Copyright 2010 Elsevier B.V. All rights reserved.

  6. The Partially Ionized Gas in the w3 Complex - C90-ALPHA Observations

    NASA Astrophysics Data System (ADS)

    Jaffe, D. T.; Wilson, T. L.

    1981-05-01

    We have mapped the distribution of the C9Oα line toward W3 with 90" resolution. The emission is centered at α=602h21m50s.6±δ=61°52'31"±9 (1950), that is, southwest of W3A (IRS 2) and toward W3 B (IRS 3). If the source and the beam are Gaussian shaped, the deconvolved source size is (121" ± 17", 88" ± 15") in (α, δ). The carbon emission covers a region which includes all of the compact radio continuum sources at the center of the W3 complex. The C II emission region shows a velocity gradient: from -39 km s-1 in the east to - 42 km s-1 in the west. It is not possible to derive uniquely the electron temperature and density of the partially ionized gas from our data or from our data in conjunction with other C II results. The carbon region may consist of shells surrounding the compact H II regions.

  7. Mass spectrometric evaluation of the gas phase structure of noncovalent quadruplex DNA obtained by electrospray ionization

    SciTech Connect

    Edmonds, C.G.; Cheng, Xueheng; Bakhtiar, R.; Van Orden, S.; Smith, R.D.; Schlegel, C.; Camp, D.G. II

    1994-12-31

    A number of quanine-rich DNA sequences have been recognized which assemble into quadrupole-helical non-Watson/Crick hybridized structures. These sequences have been localized in a number of key regions in chromosomal DNA including telomers and transcriptional promoters. The preservation of this tetrameric association in the gas phase following electrospray ionization (ESI) has been reported in this laboratory. The authors have extended these studies by the preparation of four candidate quadruplex oligomers. Three of these (I, 5{prime}-dCGC GGG GCG-3{prime}; II, 5{prime}dCGC GGGG GCG-3{prime} and III, 5{prime}-dCGC GGGGG GCG-3{prime}) differ in the number of quanine residues available for G-quartet stacking in the quadruplex array and a fourth (HG, 5{prime}-dCGC AGGG GCG03{prime}) is a sequence prominent in human telomeric DNA. During their preparation, the authors observed remarkable stability of the multimeric species in the condensed phase including intact migration in HPLC under apparently {open_quotes}denaturing{close_quotes} conditions. Under standard conditions (aqueous solution of oligonucleotide samples and nozzle-skimmer interface) on a linear quadrupole mass spectrometer oligonucleotide samples showed the typical distribution of charge states for unassociated oligonucleotides. ESI from phosphate-EDTA buffered solutions with the utilization of a capillary/skimmer interface arrangement which provides mild conditions for transfer of ions through the atmosphere/vacuum interface afforded spectra which show prominent contributions from species with quadrupole stoichiometry together monomeric materials.

  8. High resolution resonance ionization imaging detector and method

    DOEpatents

    Winefordner, James D.; Matveev, Oleg I.; Smith, Benjamin W.

    1999-01-01

    A resonance ionization imaging device (RIID) and method for imaging objects using the RIID are provided, the RIID system including a RIID cell containing an ionizable vapor including monoisotopic atoms or molecules, the cell being positioned to intercept scattered radiation of a resonance wavelength .lambda..sub.1 from the object which is to be detected or imaged, a laser source disposed to illuminate the RIID cell with laser radiation having a wavelength .lambda..sub.2 or wavelengths .lambda..sub.2, .lambda..sub.3 selected to ionize atoms in the cell that are in an excited state by virtue of having absorbed the scattered resonance laser radiation, and a luminescent screen at the back surface of the RIID cell which presents an image of the number and position of charged particles present in the RIID cell as a result of the ionization of the excited state atoms. The method of the invention further includes the step of initially illuminating the object to be detected or imaged with a laser having a wavelength selected such that the object will scatter laser radiation having the resonance wavelength .lambda..sub.1.

  9. Ionization monitor with improved ultra-high megohm resistor

    DOEpatents

    Burgess, Edward T.

    1988-11-05

    An ionization monitor measures extremely small currents using a resistor containing a beta emitter to generate ion-pairs which are collected as current when the device is used as a feedback resistor in an electrometer circuit. By varying the amount of beta emitter, the resistance of the resistor may be varied.

  10. Rapid comprehensive characterization of crude oils by thermogravimetry coupled to fast modulated gas chromatography-single photon ionization time-of-flight mass spectrometry.

    PubMed

    Wohlfahrt, S; Fischer, M; Saraji-Bozorgzad, M; Matuschek, G; Streibel, T; Post, E; Denner, T; Zimmermann, R

    2013-09-01

    Comprehensive multi-dimensional hyphenation of a thermogravimetry device (i.e. a thermobalance) to gas chromatography and single photon ionization-time-of-flight mass spectrometry (TG-GC×SPI-MS) has been used to investigate two crude oil samples of different geographical origin. The source of the applied vacuum ultraviolet radiation is an electron beam pumped rare gas excimer lamp (EBEL). The soft photoionization favors the formation of molecular ions. Introduction of a fast, rapidly modulated gas chromatographic separation step in comparison with solely TG-SPI-MS enables strongly enhanced detection especially with such highly complex organic matrices as crude oil. In contrast with former TG-SPI-MS measurements, separation and identification of overlying substances is possible because of different GC retention times. The specific contribution of isobaric compounds to one mass signal is determined for alkanes, naphthalenes, alkylated benzenes, and other compounds.

  11. Determination of phthalate esters in cosmetics by gas chromatography with flame ionization detection and mass spectrometric detection.

    PubMed

    Chen, Huiming; Wang, Chao; Wang, Xing; Hao, Nan; Liu, Juan

    2005-08-01

    A gas chromatography coupled with flame ionization detection (GC-FID) and mass spectrometric detection (MSD) method was developed to determine the six kinds of phthalate esters [dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DOP)] in cosmetics (solid, cream and liquid cosmetics). The cosmetics were extracted with methanol by ultrasonic and then separated with high-speed centrifugation. The upper clear layer was dried and filtered through a 0.45 mum pore diameter filter. The filtrate was injected into GC-FID/GC-MS for detection. GC-FID chromatogram was applied for qualitative analysis, external standard method was used for quantitative analysis. Confirmation of phthalate presence was undertaken by GC-EI-MS. The recovery range of all phthalates were between 92.0 and 110.0% with relative standard deviations between 1.95 and 5.92%. The low detection limits of the method were: 0.1 ng for DMP, DEP, DBP and BBP, 0.5 ng for DEHP and DOP. The method had advantages of high precision and sensitivity, simplicity of pretreatment. The method can be used to test the six kinds of phthalate esters in cosmetics.

  12. Application of gas chromatography with a pulsed discharge helium ionization detector for measurements of molecular hydrogen in the atmosphere.

    PubMed

    Novelli, P C; Crotwell, A M; Hall, B D

    2009-04-01

    The Earth's troposphere contains approximately 160 Tg H2 with an average surface mixing ratio approximately 530 nmole mole(-1) (ppb) and lifetime of 2 years. Atmospheric H2 is typically measured using gas chromatography (GC) followed by hot mercuric oxide reduction detection (GC-HgO). Here we describe an alternate method using GC with a pulsed-discharge helium ionization detector (HePPD). HePPD is a universal detector; when applied to H2, the GC-HePDD provides a wide linear range (0.3% over a range of 2000 ppb), a detection limit of approximately 0.03 pg, high precision (0.12%) and a stable response (+/-1.6% over nearly one year). HePPD is compared to HgO reduction using a suite of gravimetrically prepared reference gases spanning remote to urban concentrations. The method is excellent for atmospheric measurements as it provides a wide linear range with high precision, stability and reproducibility. We suggest these characteristics will improve the ability to maintain reference gases and improve measurements of atmospheric H2, thus providing better constraints on potential future changes in its sources and sinks.

  13. Thermospray ionization liquid chromatography-mass spectrometry and chemical ionization gas chromatography- mass spectrometry of hexazinone metabolites in soil and vegetation extracts

    Treesearch

    Joseph B. Fischer; Jerry L. Michael

    1995-01-01

    We have used thermospray LC-MS to confirm three highly polar metabolites (A, B. and G) of the herbicide hexazinone [3-cyclohexyl-6-(dimethylamino)-l-methyl-1,3,5-triazine-2,4(1H,3H)-dione]. and chemical ionization GC-MS to confirm two other metabolites (D and E) in extracts of soil and vegetation from a forest in the Central Alabama Piedmont. Selected-ion monitoring (...

  14. SDSS-IV MaNGA: the impact of diffuse ionized gas on emission-line ratios, interpretation of diagnostic diagrams and gas metallicity measurements

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Yan, Renbin; Bundy, Kevin; Bershady, Matthew; Haffner, L. Matthew; Walterbos, René; Maiolino, Roberto; Tremonti, Christy; Thomas, Daniel; Drory, Niv; Jones, Amy; Belfiore, Francesco; Sánchez, Sebastian F.; Diamond-Stanic, Aleksandar M.; Bizyaev, Dmitry; Nitschelm, Christian; Andrews, Brett; Brinkmann, Jon; Brownstein, Joel R.; Cheung, Edmond; Li, Cheng; Law, David R.; Roman Lopes, Alexandre; Oravetz, Daniel; Pan, Kaike; Storchi Bergmann, Thaisa; Simmons, Audrey

    2017-04-01

    Diffuse ionized gas (DIG) is prevalent in star-forming galaxies. Using a sample of 365 nearly face-on star-forming galaxies observed by Mapping Nearby Galaxies at APO, we demonstrate how DIG in star-forming galaxies impacts the measurements of emission-line ratios, hence the interpretation of diagnostic diagrams and gas-phase metallicity measurements. At fixed metallicity, DIG-dominated low ΣHα regions display enhanced [S II]/Hα, [N II]/Hα, [O II]/Hβ and [O I]/Hα. The gradients in these line ratios are determined by metallicity gradients and ΣHα. In line ratio diagnostic diagrams, contamination by DIG moves H II regions towards composite or low-ionization nuclear emission-line region (LI(N)ER)-like regions. A harder ionizing spectrum is needed to explain DIG line ratios. Leaky H II region models can only shift line ratios slightly relative to H II region models, and thus fail to explain the composite/LI(N)ER line ratios displayed by DIG. Our result favours ionization by evolved stars as a major ionization source for DIG with LI(N)ER-like emission. DIG can significantly bias the measurement of gas metallicity and metallicity gradients derived using strong-line methods. Metallicities derived using N2O2 are optimal because they exhibit the smallest bias and error. Using O3N2, R23, N2 = [N II]/Hα and N2S2Hα to derive metallicities introduces bias in the derived metallicity gradients as large as the gradient itself. The strong-line method of Blanc et al. (IZI hereafter) cannot be applied to DIG to get an accurate metallicity because it currently contains only H II region models that fail to describe the DIG.

  15. Identification of Guest-Host Inclusion Complexes in the Gas Phase by Electrospray Ionization-Mass Spectrometry

    ERIC Educational Resources Information Center

    Mendes, De´bora C.; Ramamurthy, Vaidhyanathan; Da Silva, Jose´ P.

    2015-01-01

    In this laboratory experiment, students follow a step-by-step procedure to prepare and study guest-host complexes in the gas phase using electrospray ionization-mass spectrometry (ESI-MS). Model systems are the complexes of hosts cucurbit[7]uril (CB7) and cucurbit[8]uril (CB8) with the guest 4-styrylpyridine (SP). Aqueous solutions of CB7 or CB8…

  16. Identification of Guest-Host Inclusion Complexes in the Gas Phase by Electrospray Ionization-Mass Spectrometry

    ERIC Educational Resources Information Center

    Mendes, De´bora C.; Ramamurthy, Vaidhyanathan; Da Silva, Jose´ P.

    2015-01-01

    In this laboratory experiment, students follow a step-by-step procedure to prepare and study guest-host complexes in the gas phase using electrospray ionization-mass spectrometry (ESI-MS). Model systems are the complexes of hosts cucurbit[7]uril (CB7) and cucurbit[8]uril (CB8) with the guest 4-styrylpyridine (SP). Aqueous solutions of CB7 or CB8…

  17. Ionization of highly charged iodine ions near the Bohr velocity

    NASA Astrophysics Data System (ADS)

    Zhou, Xianming; Cheng, Rui; Lei, Yu; Sun, Yuanbo; Ren, Jieru; Liu, Shidong; Deng, Jiachuan; Zhao, Yongtao; Xiao, Guoqing

    2015-01-01

    We have measured the L-shell X-rays of iodine from the collisions of 3 MeV Iq+(q=15,20,22,25,26) ions with an iron target. It is found that the X-ray yield decreases with the increasing initial charge state. The energy of the subshell X-ray has a blue shift, which is independent of the projectile charge state. In addition, the relative intensity ratios of Lβ1,3,4 and Lβ2,15 to Lα1,2 X-ray are obtained and compared with the theoretical calculations. That they are larger than for a singly ionized atom can be understood by the multiple ionization effect of the outer-shell electrons.

  18. Low-Frequency Observations of Galactic Supernova Remnants and the Distribution of Low-Density Ionized Gas in the Interstellar Medium

    DTIC Science & Technology

    1989-12-15

    New long-wavelength observations of Galactic supernova remnants ( SNRs ) at 30.9 and 57.5 MHz are used to derive detailed low-frequency radio spectra...for 32 SNRs . Of these, approximately two-thirds show turnovers at low frequencies, implying the presence of a widespread, but inhomogeneous, ionized... SNRs and to constrain the physical properties of the ionized gas responsible for the absorption. Three generally accepted ionized components of the

  19. An approach toward quantification of organic compounds in complex environmental samples using high-resolution electrospray ionization mass spectrometry

    SciTech Connect

    Nguyen, Tran B.; Nizkorodov, Sergey; Laskin, Alexander; Laskin, Julia

    2013-01-07

    Quantitative analysis of individual compounds in complex mixtures using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) is complicated by differences in the ionization efficiencies of analyte molecules in the mixture, resulting in signal suppression during ionization. However, the ability to obtain concentration estimates of compounds in an environmental sample is important for data interpretation and comparison. We introduce an approach for estimating mass concentrations of analytes observed in a multicomponent mixture by HR-ESI-MS, without prior separation. The approach relies on a calibration of the instrument using appropriate standards added to the mixture of studied analytes. An illustration of how the proposed calibration can be applied in practice is provided for aqueous extracts of isoprene photooxidation organic aerosol, with multifunctional organic acids standards. We show that the observed ion sensitivities in ESI-MS are positively correlated with the “adjusted mass,” defined as a product of the molecular mass and the H/C ratio in the molecule (adjusted mass = H/C x molecular mass). The correlation of the observed ESI sensitivity with adjusted mass is justified by considering trends of the physical and chemical properties of organic compounds that affect ionization in the positive ion mode, i.e., gas-phase basicity, polarizability, and molecular size.

  20. Behavioral Incapacitation from a High Dose of Ionizing Radiation

    DTIC Science & Technology

    1993-11-01

    1983. (UNCLASSIFIED) SMcMillan, G., Falkenberg , S., and Thompson, WI Early behavioral effects of ionizing radiation on fou• r species pf subhuman...aspect of Os, collection of iformatlort, indudkg Suggestions for reducing ttds burden, to Wahs ton HeadQuarters Services Directoralte f r infomratlon...wiere employed at the AFRRI in 1981 when the research was completed. R . W. Young and C. G. Franz were investigators in the Behavioral Science Department

  1. Highly ionized xenon and volumetric weighting in restricted focal geometries

    NASA Astrophysics Data System (ADS)

    Strohaber, J.; Kolomenskii, A. A.; Schuessler, H. A.

    2015-08-01

    The ionization of xenon atoms subjected to 42 fs, 800 nm pulses of radiation from a Ti:Sapphire laser was investigated. In our experiments, a maximum laser intensity of ˜ 2 × 10 15 W / cm 2 was used. Xenon ions were measured using a time-of-flight ion mass spectrometer having an entrance slit with dimensions of 12 μ m × 400 μ m . The observed yields Xe n + ( n = 1 - 7 ) were partially free of spatial averaging. The ion yields showed sequential and nonsequential multiple ionization and dip structures following saturation. To investigate the dip structures and to perform a comparison between experimental and simulated data, with the goal of clarifying the effects of residual spatial averaging, we derived a hybrid analytical-numerical solution for the integration kernel in restricted focal geometries. We simulated xenon ionization using Ammosov-Delone-Krainov and Perelomov-Popov-Terent'ev theories and obtained agreement with the results of observations. Since a large number of experiments suffer from spatial averaging, the results presented are important to correctly interpret experimental data by taking into account spatial averaging.

  2. The Gaia-ESO Survey: dynamics of ionized and neutral gas in the Lagoon nebula (M 8)

    NASA Astrophysics Data System (ADS)

    Damiani, F.; Bonito, R.; Prisinzano, L.; Zwitter, T.; Bayo, A.; Kalari, V.; Jiménez-Esteban, F. M.; Costado, M. T.; Jofré, P.; Randich, S.; Flaccomio, E.; Lanzafame, A. C.; Lardo, C.; Morbidelli, L.; Zaggia, S.

    2017-08-01

    Aims: We present a spectroscopic study of the dynamics of the ionized and neutral gas throughout the Lagoon nebula (M 8), using VLT-FLAMES data from the Gaia-ESO Survey. The new data permit exploration of the physical connections between the nebular gas and the stellar population of the associated star cluster NGC 6530. Methods: We characterized through spectral fitting emission lines of Hα, [N II] and [S II] doublets, [O III], and absorption lines of sodium D doublet, using data from the FLAMES-Giraffe and UVES spectrographs, on more than 1000 sightlines toward the entire face of the Lagoon nebula. Gas temperatures are derived from line-width comparisons, densities from the [S II] doublet ratio, and ionization parameter from Hα/[N II] ratio. Although doubly-peaked emission profiles are rarely found, line asymmetries often imply multiple velocity components along the same line of sight. This is especially true for the sodium absorption, and for the [O III] lines. Results: Spatial maps for density and ionization are derived, and compared to other known properties of the nebula and of its massive stars 9 Sgr, Herschel 36 and HD 165052 which are confirmed to provide most of the ionizing flux. The detailed velocity fields across the nebula show several expanding shells, related to the cluster NGC 6530, the O stars 9 Sgr and Herschel 36, and the massive protostar M 8East-IR. The origins of kinematical expansion and ionization of the NGC 6530 shell appear to be different. We are able to put constrains on the line-of-sight (relative or absolute) distances between some of these objects and the molecular cloud. The data show that the large obscuring band running through the middle of the nebula is being compressed by both sides, which might explain its enhanced density. We also find an unexplained large-scale velocity gradient across the entire nebula. At larger distances, the transition from ionized to neutral gas is studied using the sodium lines. Based on observations

  3. Multiphoton ionization of atoms and ions by high-intensity X-ray lasers

    SciTech Connect

    Popruzhenko, S. B. Mur, V. D.; Popov, V. S.; Bauer, D.

    2009-06-15

    Coulomb corrections to the action function and rate of multiphoton ionization of atoms and ions in a strong linearly polarized electromagnetic field are calculated for high values of the Keldysh adiabaticity parameter. The Coulomb corrections significantly increase the ionization rate for atoms (by several orders of magnitude). An interpolation formula proposed for ionization rate is valid for arbitrary values of the adiabaticity parameter. The high accuracy of the formula is confirmed by comparison with the results of numerical calculations. The general case of elliptic polarization of laser radiation is also considered.

  4. High quality electron beam acceleration by ionization injection in laser wakefields with mid-infrared dual-color lasers

    NASA Astrophysics Data System (ADS)

    Zeng, Ming; Luo, Ji; Chen, Min; Mori, Warren B.; Sheng, Zheng-Ming; Hidding, Bernhard

    2016-06-01

    For the laser wakefield acceleration, suppression of beam energy spread while keeping sufficient charge is one of the key challenges. In order to achieve this, we propose bichromatic laser ionization injection with combined laser wavelengths of 2.4 μ m and 0.8 μ m for wakefield excitation and triggering electron injection via field ionization, respectively. A laser pulse at 2.4 μ m wavelength enables one to drive an intense acceleration structure with a relatively low laser power. To further reduce the requirement of laser power, we also propose to use carbon dioxide as the working gas medium, where carbon acts as the injection element. Our three dimensional particle-in-cell simulations show that electron beams at the GeV energy level with both low energy spreads (around 1%) and high charges (several tens of picocoulomb) can be obtained by the use of this scheme with laser peak power totaling sub-100 TW.

  5. Discovery of nine extended ionized gas clouds in a z = 0.4 cluster

    SciTech Connect

    Yagi, Masafumi; Koyama, Yusei; Kodama, Tadayuki; Gu, Liyi; Nakata, Fumiaki; Hattori, Takashi; Yoshida, Michitoshi

    2015-02-01

    From deep Hα imaging data of Suprime-Cam/Subaru, we discovered nine extended ionized gas clouds (EIG) around galaxies in the Abell 851 cluster (A851) at z = 0.4. We surveyed a 30 × 25 arcmin region, and the EIGs were found only near the cluster center (<2.3 arcmin ∼ 750 kpc). The parent galaxies of the EIGs are star-forming or post-starburst galaxies, all of which are spectroscopically confirmed members of the cluster. Four out of the nine parent galaxies show distortion of stellar distribution in the disk, which can be a sign of recent interaction, and the interaction may have made the EIGs. On the other hand, six parent galaxies (one overlaps those exhibiting distortion) show Hα emission without stars, which implies ram pressure stripping. The spectrum of the brightest parent galaxy shows a post-starburst signature and resembles the Hα stripped galaxies found in the Coma cluster. Meanwhile, two brightest parent galaxies in A851 are more massive than the EIG parent galaxies in the Coma cluster. This is consistent with a “downsizing” of star-forming galaxies, though it is still within the statistical variance. We also analyzed Suprime-Cam data of another z=0.39 cluster, CL0024+17, but found no EIGs. The key difference between A851 and CL0024+17 would be the existence of a subcluster colliding with the main body of A851, in which six or seven out of the nine parent galaxies in A851 exist, and the fraction of EIGs in the subcluster is significantly higher than the main subcluster of A851 and CL0024+17.

  6. Determination of polycyclic aromatic hydrocarbons [PAHs] in processed meat products using gas chromatography - flame ionization detector.

    PubMed

    Olatunji, Olatunde S; Fatoki, Olalekan S; Opeolu, Beatrice O; Ximba, Bhekumusa J

    2014-08-01

    The concentrations of polycyclic aromatic hydrocarbons (PAHs) in smoked, grilled and boiled meats were determined using gas chromatography - flame ionization detector (GC-FID). PAHs in the processed meats were extracted in n-hexane after hydrolysis with methanolic KOH. Clean-up was achieved using solid phase extraction in neutral-Si/basic-Si/acidic-Si/neutral-Si frits. The fractions, benzo[k]fluoranthene (BkP), benzo[a]pyrene (BaP), indeno[123-cd]pyrene (IP) and benzo[ghi]perylene (BghiP) were separated and quantified using GC-FID. The method and instrument limits of detections were 0.1, 0.1, 0.2, 0.3μg/kg and 0.5, 0.5, 1.0, 1.5μg/kg, respectively, for BkP, BaP, IP and BghiP. The method's recovery and precision generally varied between 83.69% and 94.25% with relative standard deviation (RSD) of 3.18-15.60%; and 90.38-96.71% with relative standard deviation (RSD) of 1.82-12.87% respectively. The concentration of BkP, BaP, IP and BghiP in smoked, grilled and boiled meat samples were ranged 0.64-31.54μg/kg, 0.07-7.04μg/kg, 0.09-15.03, 0.51-46.67μg/kg and 0.01-5.11μg/kg, respectively.

  7. SIGGMA: A SURVEY OF IONIZED GAS IN THE GALAXY, MADE WITH THE ARECIBO TELESCOPE

    SciTech Connect

    Liu, B.; McIntyre, T.; Terzian, Y.; Minchin, R.; Anderson, L.; Churchwell, E.; Lebron, M.; Roshi, D. Anish

    2013-10-01

    A Survey of Ionized Gas in the Galaxy, made with the Arecibo telescope (SIGGMA), uses the Arecibo L-band Feed Array (ALFA) to fully sample the Galactic plane (30 Degree-Sign {<=} l {<=} 75 Degree-Sign and -2 Degree-Sign {<=} b {<=} 2 Degree-Sign ; 175 Degree-Sign {<=} l {<=} 207 Degree-Sign and -2 Degree-Sign {<=} b {<=} 1 Degree-Sign ) observable with the telescope in radio recombination lines (RRLs). Processed data sets are being produced in the form of data cubes of 2 Degree-Sign (along l) Multiplication-Sign 4 Degree-Sign (along b) Multiplication-Sign 151 (number of channels), archived and made public. The 151 channels cover a velocity range of 600 km s{sup -1} and the velocity resolution of the survey changes from 4.2 km s{sup -1} to 5.1 km s{sup -1} from the lowest frequency channel to the highest frequency channel. RRL maps with 3.'4 resolution and a line flux density sensitivity of {approx}0.5 mJy will enable us to identify new H II regions, measure their electron temperatures, study the physics of photodissociation regions with carbon RRLs, and investigate the origin of the extended low-density medium. Twelve Hn{alpha} lines fall within the 300 MHz bandpass of ALFA; they are resampled to a common velocity resolution to improve the signal-to-noise ratio (S/N) by a factor of three or more and preserve the line width. SIGGMA will produce the most sensitive fully sampled RRL survey to date. Here, we discuss the observing and data reduction techniques in detail. A test observation toward the H II region complex S255/S257 has detected Hn{alpha} and Cn{alpha} lines with S/N > 10.

  8. Resonant two-photon ionization of fluorene rare-gas van der Waals complexes

    NASA Astrophysics Data System (ADS)

    Leutwyler, Samuel; Even, Uzi; Jortner, Joshua

    1983-12-01

    Resonant two-photon ionization combined with time-of-flight mass spectrometry was applied for the interrogation of the S0 → S1 electronic-vibrational excitations of van der Waals complexes of fluorene (FL) with rare-gas atoms and N2 in supersonic jets. Energy-resolved and mass-resolved spectra of FL ṡ Ne, FL ṡ Arn (n=1-3), FL ṡ Kr, FL ṡ Xe, and FL ṡ N2 were recorded over the energy range 0-800 cm-1 above the electronic origin of S1. The red microscopic spectral shifts of the electronic origins of FL ṡ R (R=Ar, Kr, and Xe) complexes are dominated by dispersive interactions, being proportional to the polarizability of R. The vibrational level structure of FL ṡ Rn (R=Ar, Kr, and Xe) complexes exhibits intramolecular vibrational excitations of FL, as well as intermolecular vibrations, which involve the relative motion of FL and R in the complex. The spectra of FL ṡ Ne and FL ṡ N2 reveal a rich vibrational structure in the vicinity of the electronic origin, indicating a substantial change of the nuclear configuration upon electronic excitation. Upper and lower bounds on the dissociation energies of FL ṡ R (R=Ne, Kr, and Xe) and FL ṡ Ar2 were inferred from the vibrational level structure in the mass-resolved spectra, where the disappearance of the signal of the parent van der Waals ion and the appearance of the ion signal of the fragments mark the onset of the vibrational predissociation process.

  9. Direct Probing of Criegee Intermediates from Gas-Phase Ozonolysis Using Chemical Ionization Mass Spectrometry.

    PubMed

    Berndt, Torsten; Herrmann, Hartmut; Kurtén, Theo

    2017-09-27

    Criegee intermediates (CIs), mainly formed from gas-phase ozonolysis of alkenes, are considered as atmospheric oxidants besides OH and NO3 radicals as well as ozone. Direct CI measurement techniques are inevitably needed for reliable assessment of CIs' role in atmospheric processes. We found that CIs from ozonolysis reactions can be directly probed by means of chemical ionization mass spectrometry with a detection limit of about 10(4)-10(5) molecules cm(-3). Results from quantum chemical calculations support the experimental findings. The simplest CI, CH2OO, is detectable as an adduct with protonated ethers, preferably with protonated tetrahydrofuran. Kinetic measurements yielded k(CH2OO + SO2) = (3.3 ± 0.9) × 10(-11) and k(CH2OO + acetic acid) = (1.25 ± 0.30) × 10(-10) cm(3) molecule(-1) s(-1) at 295 ± 2 K, in very good agreement with recent measurements using diiodomethane photolysis for CH2OO generation. CIs from the ozonolysis of cyclohexene, acting as surrogate for cyclic terpenes, are followed as protonated species (CI)H(+) using protonated amines as reagent ions. Kinetic investigations indicate a different reactivity of cyclohexene-derived CIs compared with that of simple CIs, such as CH2OO. It is supposed that the aldehyde group significantly influences the CI reactivity of the cyclohexene-derived CIs. The direct CI detection method presented here should allow study of the formation and reactivity of a wide range of different CIs formed from atmospheric ozonolysis reactions.

  10. Discovery of Nine Extended Ionized Gas Clouds in a z = 0.4 Cluster

    NASA Astrophysics Data System (ADS)

    Yagi, Masafumi; Gu, Liyi; Koyama, Yusei; Nakata, Fumiaki; Kodama, Tadayuki; Hattori, Takashi; Yoshida, Michitoshi

    2015-02-01

    From deep Hα imaging data of Suprime-Cam/Subaru, we discovered nine extended ionized gas clouds (EIG) around galaxies in the Abell 851 cluster (A851) at z = 0.4. We surveyed a 30 × 25 arcmin region, and the EIGs were found only near the cluster center (\\lt 2.3 arcmin ˜ 750 kpc). The parent galaxies of the EIGs are star-forming or post-starburst galaxies, all of which are spectroscopically confirmed members of the cluster. Four out of the nine parent galaxies show distortion of stellar distribution in the disk, which can be a sign of recent interaction, and the interaction may have made the EIGs. On the other hand, six parent galaxies (one overlaps those exhibiting distortion) show Hα emission without stars, which implies ram pressure stripping. The spectrum of the brightest parent galaxy shows a post-starburst signature and resembles the Hα stripped galaxies found in the Coma cluster. Meanwhile, two brightest parent galaxies in A851 are more massive than the EIG parent galaxies in the Coma cluster. This is consistent with a “downsizing” of star-forming galaxies, though it is still within the statistical variance. We also analyzed Suprime-Cam data of another z=0.39 cluster, CL0024+17, but found no EIGs. The key difference between A851 and CL0024+17 would be the existence of a subcluster colliding with the main body of A851, in which six or seven out of the nine parent galaxies in A851 exist, and the fraction of EIGs in the subcluster is significantly higher than the main subcluster of A851 and CL0024+17.

  11. Atmospheric Pressure Chemical Ionization Gas Chromatography Mass Spectrometry for the Analysis of Selected Emerging Brominated Flame Retardants in Foods.

    PubMed

    Lv, Surong; Niu, Yumin; Zhang, Jing; Shao, Bing; Du, Zhenxia

    2017-03-10

    Emerging brominated flame retardants (eBFRs) other than polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs) and their derivatives in foods have been in focus in recent years due to their increasing production volumes, indefinite information on toxicities and the lack of data on occurrence in environments, foods as well as humans. In this study, gas chromatography was coupled to an atmospheric pressure chemical ionization-tandem mass spectrometry (APGC-MS/MS) for the analysis of six eBFRs in pork, chicken, egg, milk and fish. A short section of unpacked capillary column coupled to the end of the analytical column was applied to improve the chromatographic behaviors of high boiling point compounds. The method was comprehensively validated with method limit of quantification (mLOQ) lower than 8 pg/g wet weight (w.w.). Samples from Chinese Total Diet study were quantified following the validated APGC-MS/MS method. 2,3,4,5-pentabromo-6-ethylbenzene (PBEB), hexabromobenzene (HBB), pentabromotoluene (PBT) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) were most frequently detected in samples. The highest concentration was found in fish with 351.9 pg/g w.w. of PBT. This is the first report on the presence of PBT in food samples with non-ignorable concentrations and detection rate.

  12. Exploring petroleum hydrocarbons in groundwater by double solid phase extraction coupled to gas chromatography-flame ionization detector.

    PubMed

    Pindado Jiménez, Oscar; Pérez Pastor, Rosa Ma; Escolano Segovia, Olga; del Reino Querencia, Susana

    2015-01-01

    This work proposes an analytical procedure for measuring aliphatic and aromatic hydrocarbons fractions present in groundwater. In this method, hydrocarbons are solid phase extracted (SPE) twice from the groundwater and the resulting fractions are analyzed by gas chromatography with flame ionization detection. The first SPE disposes the hydrocarbons present in groundwater in organic solvents and the second SPE divides them into aliphatic and aromatic hydrocarbons. The validation study is carried out and its uncertainties are discussed. Identifying the main sources of uncertainty is evaluated through applying the bottom-up approach. Limits of detection for hydrocarbons ranges are below 5 µg L(-1), precision is not above of 30%, and acceptable recoveries are reached for aliphatic and aromatic fractions studied. The uncertainty due to volume of the sample, factor of calibration and recovery are the highest contributions. The expanded uncertainty range from 13% to 26% for the aliphatic hydrocarbons ranges and from 14% to 23% for the aromatic hydrocarbons ranges. As application, the proposed method is satisfactorily applied to a set of groundwater samples collected in a polluted area where there is evidence to present a high degree of hydrocarbons. The results have shown the range of aliphatic hydrocarbons >C21-C35 is the most abundant, with values ranging from 215 µg L(-1) to 354 µg L(-1), which it is associated to a contamination due to diesel.

  13. Atmospheric Pressure Chemical Ionization Gas Chromatography Mass Spectrometry for the Analysis of Selected Emerging Brominated Flame Retardants in Foods

    PubMed Central

    Lv, Surong; Niu, Yumin; Zhang, Jing; Shao, Bing; Du, Zhenxia

    2017-01-01

    Emerging brominated flame retardants (eBFRs) other than polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs) and their derivatives in foods have been in focus in recent years due to their increasing production volumes, indefinite information on toxicities and the lack of data on occurrence in environments, foods as well as humans. In this study, gas chromatography was coupled to an atmospheric pressure chemical ionization-tandem mass spectrometry (APGC-MS/MS) for the analysis of six eBFRs in pork, chicken, egg, milk and fish. A short section of unpacked capillary column coupled to the end of the analytical column was applied to improve the chromatographic behaviors of high boiling point compounds. The method was comprehensively validated with method limit of quantification (mLOQ) lower than 8 pg/g wet weight (w.w.). Samples from Chinese Total Diet study were quantified following the validated APGC-MS/MS method. 2,3,4,5-pentabromo-6-ethylbenzene (PBEB), hexabromobenzene (HBB), pentabromotoluene (PBT) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) were most frequently detected in samples. The highest concentration was found in fish with 351.9 pg/g w.w. of PBT. This is the first report on the presence of PBT in food samples with non-ignorable concentrations and detection rate. PMID:28281659

  14. Atmospheric Pressure Chemical Ionization Gas Chromatography Mass Spectrometry for the Analysis of Selected Emerging Brominated Flame Retardants in Foods

    NASA Astrophysics Data System (ADS)

    Lv, Surong; Niu, Yumin; Zhang, Jing; Shao, Bing; Du, Zhenxia

    2017-03-01

    Emerging brominated flame retardants (eBFRs) other than polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs) and their derivatives in foods have been in focus in recent years due to their increasing production volumes, indefinite information on toxicities and the lack of data on occurrence in environments, foods as well as humans. In this study, gas chromatography was coupled to an atmospheric pressure chemical ionization-tandem mass spectrometry (APGC-MS/MS) for the analysis of six eBFRs in pork, chicken, egg, milk and fish. A short section of unpacked capillary column coupled to the end of the analytical column was applied to improve the chromatographic behaviors of high boiling point compounds. The method was comprehensively validated with method limit of quantification (mLOQ) lower than 8 pg/g wet weight (w.w.). Samples from Chinese Total Diet study were quantified following the validated APGC-MS/MS method. 2,3,4,5-pentabromo-6-ethylbenzene (PBEB), hexabromobenzene (HBB), pentabromotoluene (PBT) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) were most frequently detected in samples. The highest concentration was found in fish with 351.9 pg/g w.w. of PBT. This is the first report on the presence of PBT in food samples with non-ignorable concentrations and detection rate.

  15. Determination of free amino compounds in betalainic fruits and vegetables by gas chromatography with flame ionization and mass spectrometric detection.

    PubMed

    Kugler, Florian; Graneis, Stephan; Schreiter, Pat P-Y; Stintzing, Florian C; Carle, Reinhold

    2006-06-14

    Amino acids and amines are the precursors of betalains. Therefore, the profiles of free amino compounds in juices obtained from cactus pears [Opuntia ficus-indica (L.) Mill. cv. Bianca, cv. Gialla, and cv. Rossa], pitaya fruits [Selenicereus megalanthus (K. Schumann ex Vaupel) Moran, Hylocereus polyrhizus (Weber) Britton & Rose, and Hylocereus undatus (Haworth) Britton & Rose], and in extracts from differently colored Swiss chard [Beta vulgaris L. ssp. cicla (L.) Alef. cv. Bright Lights] petioles and red and yellow beets (B. vulgaris L. ssp. vulgaris var. conditiva Alef. cv. Burpee's Golden) were investigated for the first time. Amino compounds were derivatized with propyl chloroformate. While gas chromatography (GC) with mass spectrometry was used for peak assignment, GC flame ionization detection was applied for quantification of individual compounds. Whereas proline was the major free amino compound of cactus pear and pitaya fruit juices, glutamine dominated in Swiss chard stems and beets, respectively. Interestingly, extremely high concentrations of dopamine were detected in Swiss chard stems and beets. Furthermore, the cleavage of betaxanthins caused by derivatization in alkaline reaction solutions is demonstrated for the first time. Amino acids and amines thus released might increase the actual free amino compound contents of the respective sample. To evaluate the contribution of betaxanthin cleavage to total amino acid and amine concentration, isolated betaxanthins were derivatized according to the "EZ:faast" method prior to quantification of the respective amino compounds released. On a molar basis, betaxanthin contribution to overall amino compound contents was always below 6.4%.

  16. Compact, high energy gas laser

    DOEpatents

    Rockwood, Stephen D.; Stapleton, Robert E.; Stratton, Thomas F.

    1976-08-03

    An electrically pumped gas laser amplifier unit having a disc-like configuration in which light propagation is radially outward from the axis rather than along the axis. The input optical energy is distributed over a much smaller area than the output optical energy, i.e., the amplified beam, while still preserving the simplicity of parallel electrodes for pumping the laser medium. The system may thus be driven by a comparatively low optical energy input, while at the same time, owing to the large output area, large energies may be extracted while maintaining the energy per unit area below the threshold of gas breakdown.

  17. Scaling rule for target ionization by highly charged ions at low-to-intermediate velocities

    NASA Astrophysics Data System (ADS)

    Wu, W.; Deveney, E. F.; Datz, S.; Desai, D. D.; Krause, H. F.; Sanders, J. M.; Vane, C. R.; Cocke, C. L.; Giese, J. P.

    1996-04-01

    Cross sections for ionization of He by highly charged Clq+, Cuq+, and Iq+ (q=6-10) impact at velocities from 1.6 to 3.1 a.u. were measured. These results are compared with other experimental and theoretical results available over a wide velocity range. A universal scaling rule for target ionization by nearly bare, highly charged ions at low to intermediate velocities (0.2-3.5 a.u.) is reported.

  18. Vacuum surface flashover and high pressure gas streamers

    SciTech Connect

    Elizondo, J.M.; Krogh, M.L.; Smith, D.; Stolz, D.; Wright, S.N.; Sampayan, S.E.; Caporaso, G.J.; Vitello, P.; Tishchenko, N.

    1997-07-01

    Pre-breakdown current traces obtained during high pressure gas breakdown and vacuum surface flashover show similar signatures. The initial pre-breakdown current spike, a flat constant current phase, and the breakdown phase with voltage collapse and current surge differ mostly in magnitude. Given these similarities, a model, consisting of the initial current spike corresponding to a fast precursor streamer (ionization wave led by a photoionizing front), the flat current stage as the heating or glow phase, and the terminal avalanche and gap closure, is applied to vacuum surface flashover. A simple analytical approximation based on the resistivity changes induced in the vacuum and dielectric surface is presented. The approximation yields an excellent fit to pre-breakdown time delay vs applied field for previously published experimental data. A detailed kinetics model that includes surface and gas contributions is being developed based in the initial approximation.

  19. High-performance gas sensors with temperature measurement

    PubMed Central

    Zhang, Yong; Li, Shengtao; Zhang, Jingyuan; Pan, Zhigang; Min, Daomin; Li, Xin; Song, Xiaoping; Liu, Junhua

    2013-01-01

    There are a number of gas ionization sensors using carbon nanotubes as cathode or anode. Unfortunately, their applications are greatly limited by their multi-valued sensitivity, one output value corresponding to several measured concentration values. Here we describe a triple-electrode structure featuring two electric fields with opposite directions, which enable us to overcome the multi-valued sensitivity problem at 1 atm in a wide range of gas concentrations. We used a carbon nanotube array as the first electrode, and the two electric fields between the upper and the lower interelectrode gaps were designed to extract positive ions generated in the upper gap, hence significantly reduced positive ion bombardment on the nanotube electrode, which allowed us to maintain a high electric field near the nanotube tips, leading to a single-valued sensitivity and a long nanotube life. We have demonstrated detection of various gases and simultaneously monitoring temperature, and a potential for applications. PMID:23405281

  20. Ionization and acceleration of heavy ions in high-Z solid target irradiated by high intensity laser

    NASA Astrophysics Data System (ADS)

    Kawahito, D.; Kishimoto, Y.

    2016-05-01

    In the interaction between high intensity laser and solid film, an ionization dynamics inside the solid is dominated by fast time scale convective propagation of the internal sheath field and the slow one by impact ionization due to heated high energy electrons coupled with nonlocal heat transport. Furthermore, ionization and acceleration due to the localized external sheath field which co- propagates with Al ions constituting the high energy front in the vacuum region. Through this process, the maximum charge state and then q/A increase in the rear side, so that ions near the front are further accelerated to high energy.

  1. Warm ionized gas in CALIFA early-type galaxies. 2D emission-line patterns and kinematics for 32 galaxies

    NASA Astrophysics Data System (ADS)

    Gomes, J. M.; Papaderos, P.; Kehrig, C.; Vílchez, J. M.; Lehnert, M. D.; Sánchez, S. F.; Ziegler, B.; Breda, I.; Dos Reis, S. N.; Iglesias-Páramo, J.; Bland-Hawthorn, J.; Galbany, L.; Bomans, D. J.; Rosales-Ortega, F. F.; Cid Fernandes, R.; Walcher, C. J.; Falcón-Barroso, J.; García-Benito, R.; Márquez, I.; Del Olmo, A.; Masegosa, J.; Mollá, M.; Marino, R. A.; González Delgado, R. M.; López-Sánchez, Á. R.; CALIFA Collaboration

    2016-04-01

    Context. The morphological, spectroscopic, and kinematical properties of the warm interstellar medium (wim) in early-type galaxies (ETGs) hold key observational constraints to nuclear activity and the buildup history of these massive, quiescent systems. High-quality integral field spectroscopy (IFS) data with a wide spectral and spatial coverage, such as those from the CALIFA survey, offer an unprecedented opportunity for advancing our understanding of the wim in ETGs. Aims: This article centers on a 2D investigation of the wim component in 32 nearby (≲150 Mpc) ETGs from CALIFA, complementing a previous 1D analysis of the same sample. Methods: The analysis presented here includes Hα intensity and equivalent width (EW) maps and radial profiles, diagnostic emission-line ratios, and ionized-gas and stellar kinematics. It is supplemented by τ-ratio maps, which are a more efficient means to quantify the role of photoionization by the post-AGB stellar component than alternative mechanisms (e.g., AGN, low-level star formation). Results: Confirming and strengthening our previous conclusions, we find that ETGs span a broad continuous sequence in the properties of their wim, exemplified by two characteristic classes. The first (type i) comprises systems with a nearly constant EW(Hα) in their extranuclear component, which quantitatively agrees with (but is no proof of) the hypothesis that photoionization by the post-AGB stellar component is the main driver of extended wim emission. The second class (type ii) stands for virtually wim-evacuated ETGs with a very low (≤0.5 Å), outwardly increasing EW(Hα). These two classes appear indistinguishable from one another by their LINER-specific emission-line ratios in their extranuclear component. Here we extend the tentative classification we proposed previously by the type i+, which is assigned to a subset of type i ETGs exhibiting ongoing low-level star-forming activity in their periphery. This finding along with faint

  2. Effect of high dose natural ionizing radiation on the immune system of the exposed residents of Ramsar Town, Iran.

    PubMed

    Attar, Massoud; Molaie Kondolousy, Yaghob; Khansari, Nemat

    2007-06-01

    Iran is one of several countries that has regions of high dose natural ionizing radiation. Two well-known villages in the suburb of Ramsar Town in the Caspian Sea strip, Taleshmahaleh and Chaparsar, have background radiation that is 13 times higher than normal. This radiation is the result of Radium 226 and Radon gas both of which are highly water soluble. While people living in these regions do not suffer from any major health problems, we decided to study the their immune responses to infection and inflammation in order to determine if their habitat affects their immune defense mechanisms as a way of compensating for their exposure to high dose environmental ionizing radiation. Our results showed that the total serum antioxidant level in the exposed people was significantly lower than the individuals not exposed to high dose natural ionizing radiation. The exposed individuals also had higher lymphocyte-induced IL-4 and IL-10 production, and lower IL-2 and IFN-gamma production. In addition, neutrophil NBT, phagocytosis, and locomotion were higher in the exposed group. In contrast, lymphocyte proliferation in response to PHA was unaffected. We conclude that the immune system of individuals exposed to high dose ionizing radiation has adapted to its environment by shifting from a Type 1 to a Type 2 response to promote anti-inflammation. This may be because inflammatory Type 1 responses generate more free radicals than Type 2 responses, in addition to the free radicals generated as a result of high environmental radiation. Thus, the serum total antioxidant level in the exposed residents was lower than the unexposed group.

  3. Highly sensitive solids mass spectrometer uses inert-gas ion source

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Mass spectrometer provides a recorded analysis of solid material surfaces and bulk. A beam of high-energy inert-gas ions bombards the surface atoms of a sample and converts a percentage into an ionized vapor. The mass spectrum analyzer separates the vapor ionic constituents by mass-to-charge ratio.

  4. Elemental quantitation of carbon via production of polyatomic anions in gas chromatography-plasma assisted reaction chemical ionization mass spectrometry.

    PubMed

    Haferl, Peter J; Zheng, Kunyu; Wang, Haopeng; Jorabchi, Kaveh

    2017-06-01

    Elemental mass spectrometry offers quantitation and isotopic analysis without the need for compound-specific standards. We have recently introduced plasma assisted reaction chemical ionization (PARCI) as an efficient elemental ionization method for halogens. Here, we report a new ionization chemistry in PARCI for facile quantitation of elemental carbon in gas chromatography eluates. We demonstrate that in-plasma reactions of organic compounds followed by afterglow ionization lead to formation of polyatomic anions (CN(-), OCN(-), and CO3(-)), among which CN(-) offers the best analytical sensitivity with a detection limit of ~25 pg (21 pg/s) carbon on column. Using a mixture of pesticides with wide variations in structures and heteroatom content, we demonstrate that CN(-) ion response is quantitatively correlated with the carbon concentration over two orders of magnitude (r (2) = 0.985). We show that the novel GC-PARCI-MS method provides recoveries within 80-120% using a single standard for all analytes, highlighting the strength of elemental quantitation. Further, the ability of GC-PARCI-MS to identify (13)C-tagged molecules without a priori knowledge of chemical formulas of analytes is demonstrated. Graphical abstract ᅟ.

  5. Generation of highly vibrationally excited H2 and detection by 2+1 resonantly enhanced multiphoton ionization

    NASA Astrophysics Data System (ADS)

    Robie, Daniel C.; Jusinski, Leonard E.; Bischel, William K.

    1990-02-01

    We report the first detection by optical means of highly vibrationally excited H2 X1Σ+g(vx=6-11). Vibrationally excited H2 was generated using a recently discovered hot-wire effect in H2 gas, and was detected in 40 bands with 2+1 resonantly enhanced multiphoton ionization via the EF state (vEF=0-14). Rotational temperatures are in the range 200-650 K, well below that required for thermal excitation of the observed vibrational levels.

  6. Development of a highly-sensitive Penning ionization electron spectrometer using the magnetic bottle effect

    SciTech Connect

    Ota, Masahiro; Ishiguro, Yuki; Nakajima, Yutaro; Miyauchi, Naoya; Yamakita, Yoshihiro

    2016-02-01

    This paper reports on a highly-sensitive retarding-type electron spectrometer for a continuous source of electrons, in which the electron collection efficiency is increased by utilizing the magnetic bottle effect. This study demonstrates an application to Penning ionization electron spectroscopy using collisional ionization with metastable He*(2{sup 3}S) atoms. Technical details and performances of the instrument are presented. This spectrometer can be used for studies of functional molecules and assemblies, and exterior electron densities are expected to be selectively observed by the Penning ionization.

  7. Laser-induced resonance states as dynamic suppressors of ionization in high-frequency short pulses

    SciTech Connect

    Barash, Danny; Orel, Ann E.; Baer, Roi

    2000-01-01

    An adiabatic-Floquet formalism is used to study the suppression of ionization in short laser pulses. In the high-frequency limit the adiabatic equations involve only the pulse envelope where transitions are purely ramp effects. For a short-ranged potential having a single-bound state we show that ionization suppression is caused by the appearance of a laser-induced resonance state, which is coupled by the pulse ramp to the ground state and acts to trap ionizing flux. (c) 1999 The American Physical Society.

  8. Gas-phase synthesis of singly and multiply charged polyoxovanadate anions employing electrospray ionization and collision induced dissociation.

    PubMed

    Al Hasan, Naila M; Johnson, Grant E; Laskin, Julia

    2013-09-01

    Electrospray ionization mass spectrometry (ESI-MS) combined with in-source fragmentation and tandem mass spectrometry (MS/MS) experiments were used to generate a wide range of singly and multiply charged vanadium oxide cluster anions including VxOy(n-) and VxOyCl(n-) ions (x = 1-14, y = 2-36, n = 1-3), protonated clusters, and ligand-bound polyoxovanadate anions. The cluster anions were produced by electrospraying a solution of tetradecavanadate, V14O36Cl(L)5 (L = Et4N(+), tetraethylammonium), in acetonitrile. Under mild source conditions, ESI-MS generates a distribution of doubly and triply charged VxOyCl(n-) and VxOyCl(L)((n-1)-) clusters predominantly containing 14 vanadium atoms as well as their protonated analogs. Accurate mass measurement using a high-resolution LTQ/Orbitrap mass spectrometer (m/Δm = 60,000 at m/z 410) enabled unambiguous assignment of the elemental composition of the majority of peaks in the ESI-MS spectrum. In addition, high-sensitivity mass spectrometry allowed the charge state of the cluster ions to be assigned based on the separation of the major from the much less abundant minor isotope of vanadium. In-source fragmentation resulted in facile formation of smaller VxOyCl((1-2)-) and VxOy ((1-2)-) anions. Collision-induced dissociation (CID) experiments enabled systematic study of the gas-phase fragmentation pathways of the cluster anions originating from solution and from in-source CID. Surprisingly simple fragmentation patterns were obtained for all singly and doubly charged VxOyCl and VxOy species generated through multiple MS/MS experiments. In contrast, cluster anions originating directly from solution produced comparatively complex CID spectra. These results are consistent with the formation of more stable structures of VxOyCl and VxOy anions through low-energy CID. Furthermore, our results demonstrate that solution-phase synthesis of one precursor cluster anion combined with gas-phase CID is an efficient approach for the top

  9. Gas-Phase Synthesis of Singly and Multiply Charged Polyoxovanadate Anions Employing Electrospray Ionization and Collision Induced Dissociation

    NASA Astrophysics Data System (ADS)

    Al Hasan, Naila M.; Johnson, Grant E.; Laskin, Julia

    2013-09-01

    Electrospray ionization mass spectrometry (ESI-MS) combined with in-source fragmentation and tandem mass spectrometry (MS/MS) experiments were used to generate a wide range of singly and multiply charged vanadium oxide cluster anions including VxOy n- and VxOyCln- ions (x = 1-14, y = 2-36, n = 1-3), protonated clusters, and ligand-bound polyoxovanadate anions. The cluster anions were produced by electrospraying a solution of tetradecavanadate, V14O36Cl(L)5 (L = Et4N+, tetraethylammonium), in acetonitrile. Under mild source conditions, ESI-MS generates a distribution of doubly and triply charged VxOyCln- and VxOyCl(L)(n-1)- clusters predominantly containing 14 vanadium atoms as well as their protonated analogs. Accurate mass measurement using a high-resolution LTQ/Orbitrap mass spectrometer (m/Δm = 60,000 at m/z 410) enabled unambiguous assignment of the elemental composition of the majority of peaks in the ESI-MS spectrum. In addition, high-sensitivity mass spectrometry allowed the charge state of the cluster ions to be assigned based on the separation of the major from the much less abundant minor isotope of vanadium. In-source fragmentation resulted in facile formation of smaller VxOyCl(1-2)- and VxOy (1-2)- anions. Collision-induced dissociation (CID) experiments enabled systematic study of the gas-phase fragmentation pathways of the cluster anions originating from solution and from in-source CID. Surprisingly simple fragmentation patterns were obtained for all singly and doubly charged VxOyCl and VxOy species generated through multiple MS/MS experiments. In contrast, cluster anions originating directly from solution produced comparatively complex CID spectra. These results are consistent with the formation of more stable structures of VxOyCl and VxOy anions through low-energy CID. Furthermore, our results demonstrate that solution-phase synthesis of one precursor cluster anion combined with gas-phase CID is an efficient approach for the top-down synthesis of a

  10. Plasma Production via Field Ionization

    SciTech Connect

    O'Connell, C.L.; Barnes, C.D.; Decker, F.; Hogan, M.J.; Iverson, R.; Krejcik, P.; Siemann, R.; Walz, D.R.; Clayton, C.E.; Huang, C.; Johnson, D.K.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.; Zhou, M.; Deng, S.; Katsouleas, T.; Muggli, P.; Oz, E.; /Southern California U.

    2007-01-02

    Plasma production via field ionization occurs when an incoming particle beam is sufficiently dense that the electric field associated with the beam ionizes a neutral vapor or gas. Experiments conducted at the Stanford Linear Accelerator Center explore the threshold conditions necessary to induce field ionization by an electron beam in a neutral lithium vapor. By independently varying the transverse beam size, number of electrons per bunch or bunch length, the radial component of the electric field is controlled to be above or below the threshold for field ionization. Additional experiments ionized neutral xenon and neutral nitric oxide by varying the incoming beam's bunch length. A self-ionized plasma is an essential step for the viability of plasma-based accelerators for future high-energy experiments.

  11. The Townsend coefficient of ionization in atmospheric pressure rare gas plasma

    NASA Astrophysics Data System (ADS)

    Zvereva, G.

    2015-12-01

    In the work the influence of the processes characteristic for atmospheric pressure heavy inert gases discharge plasma on the value of the first Townsend ionization coefficient were investigated. Krypton plasma was considered. Calculations have shown that the greatest impact on the value of the first Townsend ionization coefficient has dissociative recombination of molecular ions, followed by descending influence processes occur: stepwise ionization, the electron-electron collisions and superelastic ones. The effect of these processes begins to appear at concentrations of electrons and excited particles higher than 1012 cm-3. At times shorter than the time of molecular ions formation, when dissociative recombination is absent, should expect a significant increase of the ionization coefficient.

  12. Isolated high-harmonic XUV photon absorption and NIR strong-field tunnel ionization

    NASA Astrophysics Data System (ADS)

    Bryan, W. A.; Frassetto, F.; Froud, C. A.; Turcu, I. C. E.; King, R. B.; Calvert, C. R.; Nemeth, G. R. A. J.; Villoresi, P.; Poletto, L.; Springate, E.

    2012-01-01

    Extreme ultraviolet (XUV) pulses with a duration of tens of femtoseconds initiate 4s-1 or 4p-1 photoionization of krypton, which populates highly excited satellite states through the electron correlation. The excited ions are then tunnel ionized to Kr2+4s-14p-1 or 4p-2 by a strong-field near-infrared (NIR) pulse of a similar duration. The XUV pulses are produced by high harmonic generation in a gas jet and we employ a state-of-the-art time-preserving monochromator to isolate individual XUV harmonic orders. An enhancement of the Kr2+ yield as a function of harmonic photon energy and XUV-pump NIR-probe delay is observed and compared with a two-step model, which allows the population of the satellite states to be inferred. Furthermore, relative 4s and 4p satellite excitation cross-sections are predicted at the photon energies studied. This proof-of-principle experiment demonstrates that isolated harmonics can be employed to pump specific electronic states, which will be highly complementary to synchrotron, attosecond and x-ray free-electron laser studies of complex systems.

  13. Direct Analysis of Oil Additives by High-Field Asymmetric Waveform Ion Mobility Spectrometry-Mass Spectrometry Combined with Electrospray Ionization and Desorption Electrospray Ionization.

    PubMed

    Da Costa, Caitlyn; Turner, Matthew; Reynolds, James C; Whitmarsh, Samuel; Lynch, Tom; Creaser, Colin S

    2016-02-16

    The analysis of corrosion inhibitors in the presence and absence of an oil matrix is reported using electrospray ionization (ESI) and desorption electrospray ionization (DESI), hyphenated with miniaturized high-field asymmetric waveform ion mobility spectrometry (FAIMS) and mass spectrometry (MS). The target analytes were successfully ionized in solution by ESI and directly from steel surfaces using DESI ambient ionization at levels ≥0.0004% w/w (4 ppm) in oil. Differences in the mass spectral profiles observed for the additive/oil mixture are attributed to differences between the ESI and DESI ionization processes. The use of FAIMS improved selectivity for ESI generated analyte ions through reduction in the chemical noise resulting from the oil matrix. DESI enabled the direct, rapid, native state interrogation of oil samples on steel surfaces without sample pretreatment, and the hyphenation of DESI with the miniaturized FAIMS enhanced the relative analyte responses of the surface-active corrosion inhibitors.

  14. "Magic" Ionization Mass Spectrometry.

    PubMed

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The “magic” that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers.

  15. "Magic" Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Trimpin, Sarah

    2016-01-01

    The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The "magic" that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers.

  16. Investigation of ionization-induced electron injection in a wakefield driven by laser inside a gas cell

    NASA Astrophysics Data System (ADS)

    Audet, T. L.; Hansson, M.; Lee, P.; Desforges, F. G.; Maynard, G.; Dobosz Dufrénoy, S.; Lehe, R.; Vay, J.-L.; Aurand, B.; Persson, A.; Gallardo González, I.; Maitrallain, A.; Monot, P.; Wahlström, C.-G.; Lundh, O.; Cros, B.

    2016-02-01

    Ionization-induced electron injection was investigated experimentally by focusing a driving laser pulse with a maximum normalized potential of 1.2 at different positions along the plasma density profile inside a gas cell, filled with a gas mixture composed of 99 %H2+1 %N2 . Changing the laser focus position relative to the gas cell entrance controls the accelerated electron bunch properties, such as the spectrum width, maximum energy, and accelerated charge. Simulations performed using the 3D particle-in-cell code WARP with a realistic density profile give results that are in good agreement with the experimental ones. The interest of this regime for optimizing the bunch charge in a selected energy window is discussed.

  17. Investigation of ionization-induced electron injection in a wakefield driven by laser inside a gas cell

    DOE PAGES

    Audet, T. L.; Hansson, M.; Lee, P.; ...

    2016-02-16

    Ionization-induced electron injection was investigated experimentally by focusing a driving laser pulse with a maximum normalized potential of 1.2 at different positions along the plasma density profile inside a gas cell, filled with a gas mixture composed of 99%H2+1%N2. Changing the laser focus position relative to the gas cell entrance controls the accelerated electron bunch properties, such as the spectrum width, maximum energy, and accelerated charge. Simulations performed using the 3D particle-in-cell code WARP with a realistic density profile give results that are in good agreement with the experimental ones. Lastly, we discuss the interest of this regime for optimizingmore » the bunch charge in a selected energy window.« less

  18. Investigation of ionization-induced electron injection in a wakefield driven by laser inside a gas cell

    SciTech Connect

    Audet, T. L.; Hansson, M.; Lee, P.; Desforges, F. G.; Maynard, G.; Dobosz Dufrénoy, S.; Lehe, R.; Vay, J. -L.; Aurand, B.; Persson, A.; Gallardo González, I.; Maitrallain, A.; Monot, P.; Wahlström, C. -G.; Lundh, O.; Cros, B.

    2016-02-16

    Ionization-induced electron injection was investigated experimentally by focusing a driving laser pulse with a maximum normalized potential of 1.2 at different positions along the plasma density profile inside a gas cell, filled with a gas mixture composed of 99%H2+1%N2. Changing the laser focus position relative to the gas cell entrance controls the accelerated electron bunch properties, such as the spectrum width, maximum energy, and accelerated charge. Simulations performed using the 3D particle-in-cell code WARP with a realistic density profile give results that are in good agreement with the experimental ones. Lastly, we discuss the interest of this regime for optimizing the bunch charge in a selected energy window.

  19. On line high dose static position monitoring by ionization chamber detector for industrial gamma irradiators.

    PubMed

    Rodrigues, Ary A; Vieira, Jose M; Hamada, Margarida M

    2010-01-01

    A 1 cm(3) cylindrical ionization chamber was developed to measure high doses on line during the sample irradiation in static position, in a (60)Co industrial plant. The developed ionization chamber showed to be suitable for use as a dosimeter on line. A good linearity of the detector was found between the dose and the accumulated charge, independently of the different dose rates caused by absorbing materials.

  20. Partially ionized gas flow and heat transfer in the separation, reattachment, and redevelopment regions downstream of an abrupt circular channel expansion.

    NASA Technical Reports Server (NTRS)

    Back, L. H.; Massier, P. F.; Roschke, E. J.

    1972-01-01

    Heat transfer and pressure measurements obtained in the separation, reattachment, and redevelopment regions along a tube and nozzle located downstream of an abrupt channel expansion are presented for a very high enthalpy flow of argon. The ionization energy fraction extended up to 0.6 at the tube inlet just downstream of the arc heater. Reattachment resulted from the growth of an instability in the vortex sheet-like shear layer between the central jet that discharged into the tube and the reverse flow along the wall at the lower Reynolds numbers, as indicated by water flow visualization studies which were found to dynamically model the high-temperature gas flow. A reasonably good prediction of the heat transfer in the reattachment region where the highest heat transfer occurred and in the redevelopment region downstream can be made by using existing laminar boundary layer theory for a partially ionized gas. In the experiments as much as 90 per cent of the inlet energy was lost by heat transfer to the tube and the nozzle wall.

  1. Electrical conductivity and velocity of highly ionized plasma flows - Theory and experiment.

    NASA Technical Reports Server (NTRS)

    Vendell, E. W.; Park, C.; Posch, R. E.

    1972-01-01

    Use of an immersible, three-coil, magnetic-induction probe, previously tested in a low-density supersonic argon jet, to measure electrical conductivity and velocity profiles of a highly ionized high-density nitrogen jet in the continuum flow regime where effects due to probe bow shocks and boundary layers might not be negligible. Measured centerline values of electrical conductivity and velocity were compared with predictions based on a theoretical analysis previously developed to study the gas as it expanded adiabatically and inviscidly from an equilibrium sonic state to the nozzle exit. The resulting numerical exit plane values for electron density and electron temperature were then substituted into the Spitzer-Haerm conductivity formula to compute a theoretical conductivity which agreed within 40% of the measured conductivity, while the calculated and experimental velocity values differed by as much as 50%. The lack of agreement was attributed to the possible use of invalid assumptions and boundary conditions in the computer analysis or to the unknown effects of shocks on the probe data.

  2. Probing the extent and content of low ionization gas in galaxies: QSO absorption and HI emission

    NASA Technical Reports Server (NTRS)

    Womble, Donna S.

    1993-01-01

    The small projected separations of some QSO's and low-redshift galaxies provide unique opportunities to study the extent and content of gas in galaxies through observation of absorption in the QSO spectra. Observations of these systems provide valuable information on the connection between the absorbing gas and the galaxy, as well as detailed information on the morphology and environment of the galaxy itself. While there is direct evidence that galaxies can produce the intervening-type QSO absorption lines, over the past decade, the study of such 'QSO-galaxy pairs' (at low redshift) has been considered unsuccessful because new detections of absorption were seldom made. A fundamental problem concerning the relation between these low-redshift systems and those seen at moderate to high redshift remains unresolved. Direct and indirect measures of galaxy absorption cross sections at moderate to high redshifts (z is approximately greater than 20.5) are much larger than the optical and HI sizes of local galaxies. However, direct comparison of the low and moderate to high redshift systems is difficult since different ions are observed in different redshift regimes. Observations are presented for a new sample of QSO-galaxy pairs. Nine new QSO's which shine through nearby galaxies (on the sky-plane) were observed to search for CaII absorption in the QSO spectra at the foreground galaxy redshifts.

  3. Method of producing a high pressure gas

    DOEpatents

    Bingham, Dennis N.; Klingler, Kerry M.; Zollinger, William T.

    2006-07-18

    A method of producing a high pressure gas is disclosed and which includes providing a container; supplying the container with a liquid such as water; increasing the pressure of the liquid within the container; supplying a reactant composition such as a chemical hydride to the liquid under pressure in the container and which chemically reacts with the liquid to produce a resulting high pressure gas such as hydrogen at a pressure of greater than about 100 pounds per square inch of pressure; and drawing the resulting high pressure gas from the container.

  4. The analysis of high explosives by liquid chromatography/electrospray ionization mass spectrometry: multiplexed detection of negative ion adducts.

    PubMed

    Mathis, John A; McCord, Bruce R

    2005-01-01

    The negative ion electrospray ionization mass spectrometric (ESI-MS) detection of adducts of high explosives with chloride, formate, acetate, and nitrate was used to demonstrate the gas-phase interaction of neutral explosives with these anions. The relative intensities of the adduct species were determined to compare the competitive formation of the selected high explosives and anions. The relative stability of the adduct species varies, yielding preferential formation of certain anionic adducts with different high explosives. To exploit this effect, an isocratic high-performance liquid chromatography (HPLC)/ESI-MS method was developed and used for the simultaneous analysis of high explosives using two different techniques for the addition of the anionic additives; pre- and post-column. The results show that the pre-column approach provides similar results with improved selectivity for specific explosives. By detecting characteristic adduct species for each explosive, this method provides a qualitative and quantitative approach for the analysis and identification of high explosives.

  5. The ionized gas at the centre of IC 10: a possible localized chemical pollution by Wolf-Rayet stars

    NASA Astrophysics Data System (ADS)

    López-Sánchez, Á. R.; Mesa-Delgado, A.; López-Martín, L.; Esteban, C.

    2011-03-01

    We present results from integral field spectroscopy with the Potsdam Multi-Aperture Spectrograph at the 3.5-m telescope at Calar Alto Observatory of the intense star-forming region [HL90] 111 at the centre of the starburst galaxy IC 10. We have obtained maps with a spatial sampling of 1 × 1 arcsec2= 3.9× 3.9 pc2 of different emission lines and analysed the extinction, physical conditions, nature of the ionization and chemical abundances of the ionized gas, as well determined locally the age of the most recent star formation event. By defining several apertures, we study the main integrated properties of some regions within [HL90] 111. Two contiguous spaxels show an unambiguous detection of the broad He IIλ4686 emission line, this feature seems to be produced by a single late-type WN star. We also report a probable N and He enrichment in the precise spaxels where the Wolf-Rayet (WR) features are detected. The enrichment pattern is roughly consistent with that expected for the pollution of the ejecta of a single or a very small number of WR stars. Furthermore, this chemical pollution is very localized (˜2 arcsec ˜7.8 pc) and it should be difficult to detect in star-forming galaxies beyond the Local Volume. We also discuss the use of the most common empirical calibrations to estimate the oxygen abundances of the ionized gas in nearby galaxies from 2D spectroscopic data. The ionization degree of the gas plays an important role when applying these empirical methods, as they tend to give lower oxygen abundances with increasing ionization degree. Based on observations collected at the Centro Astrónomico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Plank Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).Visiting Astronomer at the Instituto de Astrofísica de Canarias.

  6. Electron gyroharmonic effects in ionization and electron acceleration during high-frequency pumping in the ionosphere.

    PubMed

    Gustavsson, B; Leyser, T B; Kosch, M; Rietveld, M T; Steen, A; Brändström, B U E; Aso, T

    2006-11-10

    Optical emissions and incoherent scatter radar data obtained during high-frequency electromagnetic pumping of the ionospheric plasma from the ground give data on electron energization in an energy range from 2 to 100 eV. Optical emissions at 4278 A from N2+ that require electrons with energies above the 18 eV ionization energy give the first images ever of pump-induced ionization of the thermosphere. The intensity at 4278 A is asymmetric around the ionospheric electron gyroharmonic, being stronger above the gyroresonance. This contrasts with emissions at 6300 A from O(1D) and of electron temperature enhancements, which have minima at the gyroharmonic but have no apparent asymmetry. This direct evidence of pump-induced ionization contradicts previous indirect evidence, which indicated that ionization is most efficiently produced when the pump frequency was below the gyroharmonic.

  7. Simulation of ionization effects for high-density positron drivers in future plasma wakefield experiments

    SciTech Connect

    Bruhwiler, D.L.; Dimitrov, D.A.; Cary, J.R.; Esarey, E.; Leemans, W.P.

    2003-05-12

    The plasma wakefield accelerator (PWFA) concept has been proposed as a potential energy doubler for present or future electron-positron colliders. Recent particle-in-cell (PIC) simulations have shown that the self-fields of the required electron beam driver can tunnel ionize neutral Li, leading to plasma wake dynamics differing significantly from that of a preionized plasma. It has also been shown, for the case of a preionized plasma, that the plasma wake of a positron driver differs strongly from that of an electron driver. We will present new PIC simulations, using the OOPIC code, showing the effects of tunneling ionization on the plasma wake generated by high-density positron drivers. The results will be compared to previous work on electron drivers with tunneling ionization and positron drivers without ionization. Parameters relevant to the energy doubler and the upcoming E-164x experiment at the Stanford Linear Accelerator Center will be considered.

  8. Low-Ionization Emission Regions in Quasars: Gas Properties Probed with Broad O I and Ca II Lines

    NASA Astrophysics Data System (ADS)

    Matsuoka, Y.; Kawara, K.; Oyabu, S.

    2008-01-01

    We have compiled the emission-line fluxes of O I λ8446, O I λ11287, and the near-infrared (IR) Ca II triplet (λ8579) observed in 11 quasars. These lines are considered to emerge from the same gas as do the Fe II lines in the low-ionized portion of the broad emission line region (BELR). The compiled quasars are distributed over wide ranges of redshift (0.06 <= z<= 1.08) and of luminosity (-29.8 <= MB <= - 22.1), thus providing a useful sample to investigate the line-emitting gas properties in various quasar environments. The measured line strengths and velocities, as functions of the quasar properties, are analyzed using photoionization model calculations. We found that the flux ratio between the Ca II triplet and O I λ8446 is hardly dependent on the redshift or luminosity, indicating similar gas densities in the emission region from quasar to quasar. On the other hand, a scatter of the O I λ11287/λ8446 ratios appears to imply the diversity of the ionization parameter. These facts invoke a picture of the line-emitting gases in quasars that have similar densities and are located at regions exposed to various ionizing radiation fluxes. The observed O I line widths are found to be remarkably similar over more than 3 orders of magnitude in luminosity, which indicates a kinematically determined location of the emission region and is in clear contrast to the case of H I lines. We also argue about the dust presence in the emission region since the region is suggested to be located near the dust sublimation point at the outer edge of the BELR.

  9. Resonance ionization and time-of-flight mass spectrometry for the analysis of trace substances in complex gas mixtures

    NASA Astrophysics Data System (ADS)

    Nagel, Holger; Weickhardt, Christian; Boesl, Ulrich; Frey, Rüdiger

    1995-04-01

    The analysis of mixtures of technical gases still comprises a lot of problems: the large number of components with very different and often rapidly varying concentrations makes great demands on analytical methods. By use of conventional analytical methods, signals of trace substances may interfere with signals of main components, whereas small signals representing low concentrations are covered by signals of main substances. The resonant-enhanced multiphoton ionization (REMPI) makes use of excited intermediate states of molecules. As these states are characteristic of each substance, one or more components of interest can be ionized with high efficiency without interference of other molecules by using a special laser-wavelength. The combination of the above mentioned ionization method with a reflectron time-of-flight mass spectrometer permits a very fast and sensitive detection of preselected trace substances. As ionization processes of higher order strongly depend on the laser intensity, there is no direct relation between ion signals and concentrations of exhaust components. Quantitative assessments are based on an especially developed calibration technique that makes use of internal standards. Applied under environmental aspects, this new analytical method helps to analyze a large number of components extracted from exhaust gases of combustion engines with high time resolution (<20 ms motor synchronously), high sensitivity (1 ppm) and high quantitative accuracy (more than 10%). A preliminary list of detectable compounds contains 30 substances.

  10. A method for measuring the electron drift velocity in working gas using a Frisch-grid ionization chamber

    NASA Astrophysics Data System (ADS)

    Bai, Huaiyong; Wang, Zhimin; Zhang, Luyu; Chen, Jinxiang; Zhang, Guohui

    2016-12-01

    A method for measuring the electron drift velocity in working gas is proposed. Based on the cathode and the anode signal waveforms of the Frisch-grid ionization chamber, the electron drift velocity is extracted. With this method, the electron drift velocities in Ar + 10% CH4, Ar + 3.5% CO2 and Kr + 2.7% CO2 gases have been measured and the results are compared with the existing measurements and the simulating results. Using this method, the electron drift velocity can be monitored throughout the experiment of charged particle without bothering the measurement of other parameters, such as the energy and orientation.

  11. Extraction of thymol, eucalyptol, menthol, and camphor residues from honey and beeswax. Determination by gas chromatography with flame ionization detection.

    PubMed

    Nozal, M J; Bernal, J L; Jiménez, J J; González, M J; Higes, M

    2002-04-19

    A gas chromatographic method to determine thymol, eucalyptol (cineole), menthol and camphor residues in honey and beeswax is proposed. To isolate the compounds, three methods involving liquid-liquid extraction with methylene chloride, distillation, or solid-phase extraction on octadecylsilica cartridges can be used. The GC separation is carried out on a 60 m x 0.53 mm Stabilwax DA capillary column, using a flame ionization detector. The method is applied to the analysis of natural honey and also honey and beeswax samples from beehives treated with the above compounds.

  12. A simple and sensitive quantitation of N,N-dimethyltryptamine by gas chromatography with surface ionization detection.

    PubMed

    Ishii, A; Seno, H; Suzuki, O; Hattori, H; Kumazawa, T

    1997-01-01

    A simple and sensitive method for determination of N,N-dimethyltryptamine (DMT) by gas chromatography (GC) with surface ionization detection (SID) is presented. Whole blood or urine, containing DMT and gramine (internal standard), was subjected to solid-phase extraction with a Sep-Pak C18 cartridge before analysis by GC-SID. The calibration curve was linear in the DMT range of 1.25-20 ng/mL blood or urine. The detection limit of DMT was about 0.5 ng/mL (10 pg on-column). The recovery of both DMT and gramine spiked in biological fluids was above 86%.

  13. The Physical Conditions of Atomic Gas at High Redshift

    NASA Astrophysics Data System (ADS)

    Neeleman, Marcel

    In this thesis we provide insight into the chemical composition, physical conditions and cosmic distribution of atomic gas at high redshift. We study this gas in absorption against bright background quasars in absorption systems known as Damped Ly-alpha Systems (DLAs). These systems contain the bulk of the atomic gas at high redshift and are the likely progenitors of modern-day galaxies. In Chapter 2, we find that the atomic gas in DLAs obeys a mass-metallicity relationship that is similar to the mass-metallicity relationship seen in star-forming galaxies. The evolution of this relationship is linear with redshift, allowing for a planar equation to accurately describe this evolution, which provides a more stringent constraint on simulations modeling DLAs. Furthermore, the concomitant evolution of the mass-metallicity relationship of atomic gas and star-forming galaxies suggests an intimate link between the two. We next use a novel way to measure the physical conditions of the gas by using fine-structure line ratios of singly ionized carbon and silicon. By measuring the density of the upper and lower level states, we are able to determine the temperature, hydrogen density and electron density of the gas. We find that the conditions present in this high redshift gas are consistent with the conditions we see in the local interstellar medium (ISM). A few absorbers have higher than expected pressure, which suggests that they probe the ISM of star-forming galaxies. Finally in Chapter 4, we measure the cosmic neutral hydrogen density at redshifts below 1.6. Below this redshift, the Ly-alpha line of hydrogen is absorbed by the atmosphere, making detection difficult. Using the archive of the Hubble Space Telescope, we compile a comprehensive list of quasars for a search of DLAs at redshift below 1.6. We find that the incidence rate of DLAs and the cosmic neutral hydrogen density is smaller than previously measured, but consistent with the values both locally and at

  14. High-rangeability ultrasonic gas flowmeter for monitoring flare gas.

    PubMed

    Mylvaganam, K S

    1989-01-01

    A transit-time ultrasonic gas flowmeter for high-rangeability requirements, such as those encountered in flare-gas flow-metering, is presented. The concept of ray rescue angle for the orientation of the ultrasonic transducers in single-beam transit-time ultrasonic flowmeters is introduced to overcome the problem of ultrasonic beam drift in high-velocity flows. To overcome problems associated with noise at high velocities, a chirp signal is used. To preserve the accuracy of the meter at low velocities near zero flow, a combination of chirp and continuous-wave signals is used to interrogate the flow. Overall system performance is presented, based on results from extensive wind-tunnel tests.

  15. Large area neutron detector based on Li6 ionization chamber with integrated body-moderator of high density polyethylene

    SciTech Connect

    Ianakiev, Kiril D.; Swinhoe, Martyn T.; Chung, Kiwhan; Makela, Mark F.

    2009-06-30

    A detector was developed and funded by DHS to be a lower cost alternative to 3He detectors. A 6Li foil-l