Sample records for heavy noble gases

  1. NOBLE GASES

    EPA Science Inventory

    The Noble Gases symposium, on which this report is based, provided comprehensive coverage of the noble gases. The coverage included, but was not limited to, the properties, biokinetics, bioeffects, production and release to the environment, detection techniques, standards, and ap...

  2. Fluid clathrate system for continuous removal of heavy noble gases from mixtures of lighter gases

    DOEpatents

    Gross, Kenneth C. (Bolingbrook, IL); Markun, Francis (Joliet, IL); Zawadzki, Mary T. (South Bend, IN)

    1998-01-01

    An apparatus and method for separation of heavy noble gas in a gas volume. An apparatus and method have been devised which includes a reservoir containing an oil exhibiting a clathrate effect for heavy noble gases with a reservoir input port and the reservoir is designed to enable the input gas volume to bubble through the oil with the heavy noble gas being absorbed by the oil exhibiting a clathrate effect. The gas having reduced amounts of heavy noble gas is output from the oil reservoir, and the oil having absorbed heavy noble gas can be treated by mechanical agitation and/or heating to desorb the heavy noble gas for analysis and/or containment and allow recycling of the oil to the reservoir.

  3. Fluid clathrate system for continuous removal of heavy noble gases from mixtures of lighter gases

    DOEpatents

    Gross, K.C.; Markun, F.; Zawadzki, M.T.

    1998-04-28

    An apparatus and method are disclosed for separation of heavy noble gas in a gas volume. An apparatus and method have been devised which includes a reservoir containing an oil exhibiting a clathrate effect for heavy noble gases with a reservoir input port and the reservoir is designed to enable the input gas volume to bubble through the oil with the heavy noble gas being absorbed by the oil exhibiting a clathrate effect. The gas having reduced amounts of heavy noble gas is output from the oil reservoir, and the oil having absorbed heavy noble gas can be treated by mechanical agitation and/or heating to desorb the heavy noble gas for analysis and/or containment and allow recycling of the oil to the reservoir. 6 figs.

  4. Possible cometary origin of heavy noble gases in the atmospheres of Venus, Earth and Mars

    PubMed

    Owen, T; Bar-Nun, A; Kleinfeld, I

    1992-07-01

    Models that trace the origin of noble gases in the atmospheres of the terrestrial planets (Venus, Earth and Mars) to the 'planetary component' in chondritic meteorites confront several problems. The 'missing' xenon in the atmospheres of Mars and Earth is one of the most obvious; this gas is not hidden or trapped in surface materials. On Venus, the absolute abundances of neon and argon per gram of rock are higher even than those in carbonaceous chondrites, whereas the relative abundances of argon and krypton are closer to solar than to chondritic values (there is only an upper limit on xenon). Pepin has developed a model that emphasizes hydrodynamic escape of early, massive hydrogen atmospheres to explain the abundances and isotope ratios of noble gases on all three planets. We have previously suggested that the unusual abundances of heavy noble gases on Venus might be explained by the impact of a low-temperature comet. Further consideration of the probable history of the martian atmosphere, the noble-gas data from the (Mars-derived) SNC meteorites and laboratory experiments on the trapping of noble gases in ice lead us to propose here that the noble gases in the atmospheres of all of the terrestrial planets are dominated by a mixture of an internal component and contribution from impacting icy planetesimals (comets). If true, this hypothesis illustrates the importance of impacts in determining the volatile inventories of these planets. PMID:11536499

  5. First complete isotopic analysis of Solar Wind heavy noble gases in Genesis Aluminum collectors

    NASA Astrophysics Data System (ADS)

    Meshik, A.; Pravdivtseva, O.; Hohenberg, C. M.; Burnett, D. S.

    2011-12-01

    Analyses of noble gases implanted into Genesis Solar Wind (SW) collectors and their comparison with the gases from solar-wind rich lunar and meteoritic materials may constrain an extent of temporal variations of isotopic composition of the solar wind. Here we report our isotope measurements of all heavy noble gas isotopes including low abundant 126Xe, 124Xe and 78Kr. Two aluminum Genesis collectors were used in this study: Aluminum on Sapphire (AloS) and Polished Aluminum Collector (PAC). Solar Wind (SW) noble gases were extracted using IR- and UV-lasers operated in Q-switched mode. Purified gases were analyzed in the modified 8-multiplier mass spectrometer Noblesse, custom built by Nu-Instruments (UK) for microanalyses of heavy noble gases. SW-Ar was analyzed using UV-depth profiling, which clearly demonstrated depth dependant isotope fractionation caused by SW-implantation at constant ion velocities. The cumulative SW-Ar composition is in good agreement with our earlier analyses made by a single multiplier mass spectrometer (36Ar/38Ar = 5.501 ± 0.002, [1]). SW-Kr was found to have the following isotopic composition: 86Kr/84Kr = .3012 ± .0004, 83Kr/84Kr = .2034 ± .0002, 82Kr/84Kr = .2054 ± .0002, 80Kr/84Kr = .0412 ± .0002, and 78Kr/84Kr = .00642 ± .00005. These results are statistically indistinguishable from SW-Kr composition based on the lunar regolith data [2]. Our best current estimate of SW-Xe composition obtained from 25 independent analyses ran at different experimental conditions is: 136Xe/132Xe = .3003 ± .0006, 134Xe/132Xe = .3692 ± .0007, 131Xe/132Xe = .8263 ± .0013, 130Xe/132Xe = .1649 ± .0004, 129Xe/132Xe = 1.0401 ± .00010, 128Xe/132Xe = .0842 ± .0003, 126Xe/132Xe = .00417 ± .00009, and 124Xe/132Xe = .00492 ± .00007. Although small systematical difference between these numbers and lunar SW-Xe is observed, more accurate SW-Xe lunar regolith measurements are required to understand whether or not these differences are real. The total amounts of heavy noble gases accumulated over 853 days of collection are: (2.81 ± .19)E+10, (1.08 ± .05)E+07, and (1.15 ± .04)E+06 atoms/cm2 of 36Ar, 84Kr and 132Xe correspondently. This work is supported by NASA grant NNX07AM76G. [1] Meshik A. P. et al. Science 318, 2007, [2] Pepin R. O. et al. 1995. GCA 59.

  6. Noble gases in the moon

    NASA Technical Reports Server (NTRS)

    Manuel, O. K.; Srinivasan, B.; Hennecke, E. W.; Sinclair, D. E.

    1972-01-01

    The abundance and isotopic composition of helium, neon, argon, krypton, and xenon which were released by stepwise heating of lunar fines (15601.64) and (15271.65) were measured spectrometrically. The results of a composition of noble gases released from the lunar fines with noble gases in meteorites and in the earth are presented along with the isotopic composition of noble gases in lunar fines, in meteorites, and in the atmosphere. A study of two isotopically distinct components of trapped xenon in carbonaceous chondrites is also included.

  7. Impact regimes and post-formation sequestration processes: implications for the origin of heavy noble gases in terrestrial planets

    E-print Network

    Mousis, Olivier; Petit, Jean-Marc; Picaud, Sylvain; Schmitt, Bernard; Marquer, Didier; Horner, Jonathan; Thomas, Caroline

    2010-01-01

    The difference between the measured atmospheric abundances of neon, argon, krypton and xenon for Venus, the Earth and Mars is striking. Because these abundances drop by at least two orders of magnitude as one moves outward from Venus to Mars, the study of the origin of this discrepancy is a key issue that must be explained if we are to fully understand the different delivery mechanisms of the volatiles accreted by the terrestrial planets. In this work, we aim to investigate whether it is possible to quantitatively explain the variation of the heavy noble gas abundances measured on Venus, the Earth and Mars, assuming that cometary bombardment was the main delivery mechanism of these noble gases to the terrestrial planets. To do so, we use recent dynamical simulations that allow the study of the impact fluxes of comets upon the terrestrial planets during the course of their formation and evolution. Assuming that the mass of noble gases delivered by comets is proportional to rate at which they collide with the t...

  8. IMPACT REGIMES AND POST-FORMATION SEQUESTRATION PROCESSES: IMPLICATIONS FOR THE ORIGIN OF HEAVY NOBLE GASES IN TERRESTRIAL PLANETS

    SciTech Connect

    Mousis, Olivier; Petit, Jean-Marc; Picaud, Sylvain; Thomas, Caroline [Universite de Franche-Comte, Institut UTINAM, CNRS/INSU, UMR 6213, 25030 Besancon Cedex (France); Lunine, Jonathan I. [Dipartimento di Fisica, Universita degli Studi di Roma 'Tor Vergata', Rome (Italy); Schmitt, Bernard [Universite Joseph Fourier, Laboratoire de Planetologie de Grenoble, CNRS/INSU, UMR 5109, Observatoire de Sciences de l'Univers de Grenoble (France); Marquer, Didier [Universite de Franche-Comte, Chrono-Environnement, CNRS/INSU, UMR 6249, 25030 Besancon Cedex (France); Horner, Jonathan, E-mail: olivier.mousis@obs-besancon.f [Department of Physics, Science Laboratories, University of Durham, South Road, Durham, DH1 3LE (United Kingdom)

    2010-05-10

    The difference between the measured atmospheric abundances of neon, argon, krypton, and xenon for Venus, Earth, and Mars is striking. Because these abundances drop by at least 2 orders of magnitude as one moves outward from Venus to Mars, the study of the origin of this discrepancy is a key issue that must be explained if we are to fully understand the different delivery mechanisms of the volatiles accreted by the terrestrial planets. In this work, we aim to investigate whether it is possible to quantitatively explain the variation of the heavy noble gas abundances measured on Venus, Earth, and Mars, assuming that cometary bombardment was the main delivery mechanism of these noble gases to the terrestrial planets. To do so, we use recent dynamical simulations that allow the study of the impact fluxes of comets upon the terrestrial planets during the course of their formation and evolution. Assuming that the mass of noble gases delivered by comets is proportional to the rate at which they collide with the terrestrial planets, we show that the krypton and xenon abundances in Venus and Earth can be explained in a manner consistent with the hypothesis of cometary bombardment. In order to explain the krypton and xenon abundance differences between Earth and Mars, we need to invoke the presence of large amounts of CO{sub 2}-dominated clathrates in the Martian soil that would have efficiently sequestered these noble gases. Two different scenarios based on our model can also be used to explain the differences between the neon and argon abundances of the terrestrial planets. In the first scenario, cometary bombardment of these planets would have occurred at epochs contemporary with the existence of their primary atmospheres. Comets would have been the carriers of argon, krypton, and xenon, while neon would have been gravitationally captured by the terrestrial planets. In the second scenario, we consider impacting comets that contained significantly smaller amounts of argon, an idea supported by predictions of noble gas abundances in these bodies, provided that they formed from clathrates in the solar nebula. In this scenario, neon and argon would have been supplied to the terrestrial planets via the gravitational capture of their primary atmospheres whereas the bulk of their krypton and xenon would have been delivered by comets.

  9. Impact Regimes and Post-formation Sequestration Processes: Implications for the Origin of Heavy Noble Gases in Terrestrial Planets

    NASA Astrophysics Data System (ADS)

    Mousis, Olivier; Lunine, Jonathan I.; Petit, Jean-Marc; Picaud, Sylvain; Schmitt, Bernard; Marquer, Didier; Horner, Jonathan; Thomas, Caroline

    2010-05-01

    The difference between the measured atmospheric abundances of neon, argon, krypton, and xenon for Venus, Earth, and Mars is striking. Because these abundances drop by at least 2 orders of magnitude as one moves outward from Venus to Mars, the study of the origin of this discrepancy is a key issue that must be explained if we are to fully understand the different delivery mechanisms of the volatiles accreted by the terrestrial planets. In this work, we aim to investigate whether it is possible to quantitatively explain the variation of the heavy noble gas abundances measured on Venus, Earth, and Mars, assuming that cometary bombardment was the main delivery mechanism of these noble gases to the terrestrial planets. To do so, we use recent dynamical simulations that allow the study of the impact fluxes of comets upon the terrestrial planets during the course of their formation and evolution. Assuming that the mass of noble gases delivered by comets is proportional to the rate at which they collide with the terrestrial planets, we show that the krypton and xenon abundances in Venus and Earth can be explained in a manner consistent with the hypothesis of cometary bombardment. In order to explain the krypton and xenon abundance differences between Earth and Mars, we need to invoke the presence of large amounts of CO2-dominated clathrates in the Martian soil that would have efficiently sequestered these noble gases. Two different scenarios based on our model can also be used to explain the differences between the neon and argon abundances of the terrestrial planets. In the first scenario, cometary bombardment of these planets would have occurred at epochs contemporary with the existence of their primary atmospheres. Comets would have been the carriers of argon, krypton, and xenon, while neon would have been gravitationally captured by the terrestrial planets. In the second scenario, we consider impacting comets that contained significantly smaller amounts of argon, an idea supported by predictions of noble gas abundances in these bodies, provided that they formed from clathrates in the solar nebula. In this scenario, neon and argon would have been supplied to the terrestrial planets via the gravitational capture of their primary atmospheres whereas the bulk of their krypton and xenon would have been delivered by comets.

  10. Angular correlation studies in noble gases

    NASA Technical Reports Server (NTRS)

    Coleman, P. G.

    1990-01-01

    There has been a recent revival of interest in the measurement of angular correlation of annihilation photons from the decay of positrons and positronium in gases. This revival has been stimulated by the possibility offered by the technique to shed new light on the apparently low positronium formation fraction in the heavier noble gases and to provide information on positronium quenching processes in gases such as oxygen. There is also the potential for learning about positronium slowing down in gases. This review focuses on experimental noble gas work and considers what new information has been, and may be, gained from these studies.

  11. Resonance Ionization of Heavy Noble Gases: The Potential of KR and Xe Measurements from Single Pre-Solar Grains

    NASA Astrophysics Data System (ADS)

    Thonnard, N.

    1995-09-01

    Since the first reliable indication of the existence of non-terrestrial composition of Xe isotopes in meteorites by Reynolds [1,2], anomalies have been found in the isotopic composition of many elements in meteorites, implying a plurality of nucleosynthetic processes, and indicating that the initial conditions leading to the formation of the solar system were quite diverse [3]. Noble gases provide a unique window into the composition of the progenitor material to the solar system [4]. Stellar evolution may contribute by the s-process, r-process, p-process, etc., each with its own isotopic distribution. Kr and Xe are especially useful as the large number of isotopes (7 in the 78Kr to 86Kr range, and 9 in the 124Xe to 136Xe range) provide many clues to help unravel the multiple sources to the measured abundances. Although Xe has been measured and analyzed considerably more frequently than Kr in meteorite studies, this has only partially been due to the wealth of information derivable from Xe studies, but also, due to experimental difficulties encountered in Kr measurements. Early in the development of stellar nucleosynthesis, 86Kr was proposed as a chronometer of the s-process [5], but until recently has provided unreliable results [6]. Other interesting properties derivable from Kr isotope measurements include 78Kr as an indication of spallation history, 80Kr as a stellar thermometer, and 81Kr and 83Kr to determine cosmic ray exposure ages. Studies of highly refractory microscopic grains (diamond, graphite and SiC) separated from the much more abundant carbonaceous matrix in primitive meteorites have shown a remarkable isotopic composition diversity in a small fraction of single grains from the same meteorite, implying multiple stellar sources [4]. Ion microprobe measurements have been possible of the major constituents of single interstellar grains [7,8] and of He and Ne using a state-of-the-art static noble gas mass spectrometer [9-11]. But, a recent attempt to measure noble gases from fourteen individual "X" SiC grains, previously identified by ion microprobe analysis, was unsuccessful with the 2,000 132Xe atom detection limit of the mass spectrometer [12,13]. From the Kr concentration measurements of SiC particles KJF by Lewis et al. [6], a 2 micrometer diameter particle will on average contain 134 Kr atoms. If only 4% of the SiC grains contain the majority of the noble gas atoms, then a single gas rich grain will contain 3,350 Kr atoms, or 12, 75, 385, 398, 1910, and 580 atoms for 78Kr through 86Kr, respectively. The Xe single-grain abundances would be similar. Resonance ionization, an emerging laser-based element analysis technique, is being harnessed to a wide variety of problems in which minute quantities of a particular element need to be measured efficiently in the presence of an overwhelmingly larger background of other materials [14]. By utilizing lasers tuned to specific atomic energy levels of the analyte element, ions are produced selectively in a mass spectrometer with much higher efficiency than possible using conventional methods, such as electron bombardment, thermal ionization, or ion sputtering. In a static resonance ionization system for noble gases, the combination of high ionization efficiency and sample concentrator results in an extremely fast (~3 min. detection half-life vs. ~60 min. for conventional systems) analyzer with a detection limit of ~100 85Kr atoms [15]. In addition to the almost complete absence of interferences, the short analysis time significantly reduces the background contribution of outgassing in the mass spectrometer. Although using a less efficient laser scheme resulting in slightly slower analyses, a similar system has recently been completed and dedicated to extraterrestrial Xe measurements [16]. At the newly formed Institute for Rare Isotope Measurements [17], the noble gas equipment that had previously been at Atom Sciences [14,15] is being re-installed and upgraded to provide routine noble gas measurements from terrestrial and extraterrestrial samples. The pres

  12. Diffusive separation of noble gases and noble gas abundance patterns in sedimentary rocks

    SciTech Connect

    Torgersen, T.; Kennedy, B.M.; van Soest, M.C.

    2004-06-14

    The mechanisms responsible for noble gas concentrations, abundance patterns, and strong retentivity in sedimentary lithologies remain poorly explained. Diffusion-controlled fractionation of noble gases is modeled and examined as an explanation for the absolute and relative abundances of noble gases observed in sediments. Since the physical properties of the noble gases are strong functions of atomic mass, the individual diffusion coefficients, adsorption coefficients and atomic radii combine to impede heavy noble gas (Xe) diffusion relative to light noble gas (Ne) diffusion. Filling of lithic grains/half-spaces by diffusive processes thus produces Ne enrichments in the early and middle stages of the filling process with F(Ne) values similar to that observed in volcanic glasses. Emptying lithic grains/half-spaces produces a Xe-enriched residual in the late (but not final) stages of the process producing F(Xe) values similar to that observed in shales. 'Exotic but unexceptional' shales that exhibit both F(Ne) and F(Xe) enrichments can be produced by incomplete emptying followed by incomplete filling. This mechanism is consistent with literature reported noble gas abundance patterns but may still require a separate mechanism for strong retention. A system of labyrinths-with-constrictions and/or C-, Si-nanotubes when combined with simple adsorption can result in stronger diffusive separation and non-steady-state enrichments that persist for longer times. Enhanced adsorption to multiple C atoms inside C-nanotubes as well as dangling functional groups closing the ends of nanotubes can provide potential mechanisms for 'strong retention'. We need new methods of examining noble gases in rocks to determine the role and function of angstrom-scale structures in both the diffusive enrichment process and the 'strong retention' process for noble gas abundances in terrestrial rocks.

  13. Measuring the Isotopic Composition of Solar Wind Noble Gases

    E-print Network

    5 Measuring the Isotopic Composition of Solar Wind Noble Gases Alex Meshik, Charles Hohenberg, Olga and processes leading to the variations observed and how the present solar wind noble gases may differ from and breccias, implanted with solar wind noble gases, did provide a needed ground truth, neither by themselves

  14. Preserving noble gases in a convecting mantle.

    PubMed

    Gonnermann, Helge M; Mukhopadhyay, Sujoy

    2009-05-28

    High (3)He/(4)He ratios sampled at many ocean islands are usually attributed to an essentially undegassed lower-mantle reservoir with high (3)He concentrations. A large and mostly undegassed mantle reservoir is also required to balance the Earth's (40)Ar budget, because only half of the (40)Ar produced from the radioactive decay of (40)K is accounted for by the atmosphere and upper mantle. However, geophysical and geochemical observations suggest slab subduction into the lower mantle, implying that most or all of Earth's mantle should have been processed by partial melting beneath mid-ocean ridges and hotspot volcanoes. This should have left noble gases in both the upper and the lower mantle extensively outgassed, contrary to expectations from (3)He/(4)He ratios and the Earth's (40)Ar budget. Here we suggest a simple solution: recycling and mixing of noble-gas-depleted slabs dilutes the concentrations of noble gases in the mantle, thereby decreasing the rate of mantle degassing and leaving significant amounts of noble gases in the processed mantle. As a result, even when the mass flux across the 660-km seismic discontinuity is equivalent to approximately one lower-mantle mass over the Earth's history, high (3)He contents, high (3)He/(4)He ratios and (40)Ar concentrations high enough to satisfy the (40)Ar mass balance of the Earth can be preserved in the lower mantle. The differences in (3)He/(4)He ratios between mid-ocean-ridge basalts and ocean island basalts, as well as high concentrations of (3)He and (40)Ar in the mantle source of ocean island basalts, can be explained within the framework of different processing rates for the upper and the lower mantle. Hence, to preserve primitive noble gas signatures, we find no need for hidden reservoirs or convective isolation of the lower mantle for any length of time. PMID:19478782

  15. Noble gases and nitrogen in Muong Nong tektites

    Microsoft Academic Search

    S. V. S. Murty

    1997-01-01

    Three samples of Muong Nong tektites have been studied for N and noble gases. The isotopic composition of noble gases is air-like. The noble gas amounts are much higher than in splash form tektites. As compared to air, He and Ne have been enriched, most likely due to inward diffusion from ambient air, subsequent to glass formation. N contents range

  16. Noble Gases in the Chelyabinsk Meteorites

    NASA Technical Reports Server (NTRS)

    Haba, Makiko K.; Sumino, Hirochika; Nagao, Keisuke; Mikouchi, Takashi; Komatsu, Mutsumi; Zolensky, Michael E.

    2014-01-01

    The Chelyabinsk meteorite fell in Russia on February 15, 2013 and was classified as LL5 chondrite. The diameter before it entered the atmosphere has been estimated to be about 20 m [1]. Up to now, numerous fragments weighing much greater than 100 kg in total have been collected. In this study, all noble gases were measured for 13 fragments to investigate the exposure history of the Chelyabinsk meteorite and the thermal history of its parent asteroid.

  17. Noble Gases in the Earth's Core?

    NASA Astrophysics Data System (ADS)

    Jephcoat, A. P.; Bouhifd, M. A.; Heber, V.; Kelley, S. P.

    2004-12-01

    Chemical inertness, surface volatility and low abundance have made the noble gases a unique trace elemental and isotopic system for constraining the formation and evolution of the solid Earth and its atmosphere. This geochemical role parallels extensive physical-property measurements on the condensed rare gases alone at the pressures equivalent to those of the Earth's deep mantle and core from diamond-anvil cell (DAC) experiments. Traditional geochemical approaches to the processes of planetary evolution have involved crystal-melt partitioning at low pressures relevant more to near-surface degassing. The degree of compatibility has fluctuated among different studies and largely rests with the conclusion that, for common upper mantle phases, the noble gases are highly incompatible. But the long-known high 3He/4He ratios for some ocean-island basalts and more recent observations for some of the rare gases (Ne, Ar and possibly Xe) that there is a solar component emanating from the Earth, continue to raise questions on the source reservoir as well as on accretionary and incorporation processes. Changes in models of mantle convection style have made it harder to rely on the deep mantle as a reservoir, and the core has remained a particularly unfavourable location either because of difficulty in constructing a retention mechanism during planetary accretion or simply because of lack of data: Partitioning studies at pressure are rare and complicated by the difficulty in reproducing not only absolute concentrations, but confinement of gas in high-pressure apparatus and post-run analysis. We have investigated noble gas solubility in silicate liquids at high pressures in a DAC (relevant to a magma-ocean model of the early Earth) that suggests that the detailed composition and structure of silicate liquids may act as an important control on the level of incompatibility. The long-held idea of partial melting as a single-stage, efficient process for extracting noble gases from the Earth's mantle at all depths, may well be oversimplified. For molten metal compositions interacting with silicate melt, Matsuda et al. (1993) defined the near-zero limits of noble gas solubility expected in metal with increasing pressure. We re-visit the phenomenological aspect of (saturated) noble gas solubility in metals with new experiments in noble gas pressure-transmitting media in the laser-heated DAC. First results with argon analysed with SEM methods suggest up to an order of magnitude higher partition coefficient (D(Ar)Fe/sil ˜ 0.1) for liquids in the DAC at 5 GPa. We have also recovered samples for analysis with more sensitive UV laser-ablation mass spectroscopic techniques that provide additional, depth-resolved constraints on noble gas solubility at moderate pressures.

  18. Trapping of noble gases in proton-irradiated silicate smokes

    NASA Technical Reports Server (NTRS)

    Nichols, R. H., Jr.; Nuth, J. A., III; Hohenberg, C. M.; Olinger, C. T.; Moore, M. H.

    1992-01-01

    We have measured Ne, Ar, Kr, and Xe in Si2O3 'smokes' that were condensed on Al substrates, vapor-deposited with various mixtures of CH4, NH3, H2O3 and noble gases at 10 K and subsequently irradiated with 1 MeV protons to simulate conditions during grain mantle formation in interstellar clouds. Neither Ne nor Ar is retained by the samples upon warming to room temperature, but Xe is very efficiently trapped and retained. Kr is somewhat less effectively retained, typically depleted by factors of about 10-20 relative to Xe. Isotopic fractionation favoring the heavy isotopes of Xe and Kr of about 5-10-percent/amu is observed. Correlations between the specific chemistry of the vapor deposition and heavy noble gas retention are most likely the result of competition by the various species for irradiation-produced trapping sites. The concentration of Xe retained by some of these smokes exceeds that observed in phase Q of meteorites and, like phase Q, they do not seem to be carriers of the light noble gases.

  19. Solubility of noble gases in serpentine - Implications for meteoritic noble gas abundances

    NASA Technical Reports Server (NTRS)

    Zaikowski, A.; Schaeffer, O. A.

    1979-01-01

    An investigation of the solubilities of the noble gases from synthesis and solubility studies of the sheet silicate mineral serpentine in carbonaceous chondrites is presented. Hydrothermal synthesis and exchange experiments were made at 340C and 1 kbar with noble gas partial pressures from 2 times 10 to the -8th power to 0.1 atm. The measured distribution coefficients for noble gases are not sufficiently high to account for the trapped noble gases in carbonaceous chondrites by exchange in solar nebula if meteoritic minerals have comparable distribution coefficients. Also, serpentine gains and loses noble gases to approach equilibrium values with the terrestrial atmosphere, indicating that this exposure may have influenced the noble gas abundances in phyllosilicate minerals of these chondrites. The dispersion of K-Ar ages of carbonaceous chondrites could be the result of phyllosilicates approaching equilibrium solubility of atmospheric Ar-40.

  20. Trends In Positron Scattering From Noble Gases

    NASA Astrophysics Data System (ADS)

    Jones, A.; Caradonna, P.; Machacek, P.; Makochekanwa, C.; Slaughter, D.; McEachran, R.; Sullivan J.; Buckman, S.

    2010-07-01

    We have a program of low energy (< 100 eV), high resolution (~ 60 meV), positron scattering from atoms and molecules which is being facilitated by a high-flux, trapbased positron beamline facility at the Australian National University (Sullivan et al. 2008). The positron beam utilised is a pulsed beam which operates at about 100 Hz. A typical pulse will contain about 1000 positrons. For noble gases, our goals range from establishing "benchmarks" for positron scattering cross sections, to investigation of threshold effects in processes such as positronium formation and ionization. This paper will present examples of trends observed in a number of scattering processes in He, Ne, Ar, Kr and Xe. The project includes investigations of the - elastic cross sections - positronium formation cross sections - total cross sections Where possible the current experimental results will be compared with the best available theoretical calculations and other experimental data from literature.

  1. Biomedical imaging with hyperpolarized noble gases

    NASA Astrophysics Data System (ADS)

    Ruppert, Kai

    2014-11-01

    Hyperpolarized noble gases (HNGs), polarized to approximately 50% or higher, have led to major advances in magnetic resonance (MR) imaging of porous structures and air-filled cavities in human subjects, particularly the lung. By boosting the available signal to a level about 100?000 times higher than that at thermal equilibrium, air spaces that would otherwise appear as signal voids in an MR image can be revealed for structural and functional assessments. This review discusses how HNG MR imaging differs from conventional proton MR imaging, how MR pulse sequence design is affected and how the properties of gas imaging can be exploited to obtain hitherto inaccessible information in humans and animals. Current and possible future imaging techniques, and their application in the assessment of normal lung function as well as certain lung diseases, are described.

  2. Sir William Ramsay and the noble gases.

    PubMed

    Davies, Alwyn G

    2012-01-01

    Sir William Ramsay was one of the world's leading scientists at the end of the 19th century, and in a spectacular period of research between 1894 and 1898, he discovered five new elements. These were the noble gases, helium, neon, argon, krypton, and xenon; they added a whole new group to the Periodic Table of the elements, and provided the keystone to our understanding of the electronic structure of atoms, and the way those electrons bind the atoms together into molecules. For this work he was awarded the Nobel Prize in Chemistry in 1904, the first such prize to come to a British subject. He was also a man of great charm, a good linguist, and a composer and performer of music, poetry and song. This review will trace his career, describe his character and give and account of the chemistry which led to the award of the Nobel Prize. PMID:22574384

  3. Removal of Titan's Atmospheric Noble Gases by their Sequestration in Surface Clathrates

    E-print Network

    Mousis, Olivier; Picaud, Sylvain; Cordier, Daniel; Waite, J Hunter; Jr.,; Mandt, Kathleen E

    2011-01-01

    A striking feature of the atmosphere of Titan is that no heavy noble gases other than argon were detected by the Gas Chromatograph Mass Spectrometer (GCMS) aboard the Huygens probe during its descent to Titan's surface in January 2005. Here we provide an explanation of the mysterious absence or rarity of these noble gases in Titan's atmosphere: the thermodynamic conditions prevailing at the surface-atmosphere interface of the satellite allow the formation of multiple guest clathrates that preferentially store some species, including all heavy noble gases, over others. The clean water ice needed for formation of these clathrates could be delivered by successive episodes of cryovolcanic lavas that have been hypothesized to regularly cover the surface of Titan. The formation of clathrates in the porous lavas and their propensity for trapping Ar, Kr and Xe would progressively remove these species from the atmosphere of Titan over its history. In some circumstances, a global clathrate crust with an average thickne...

  4. The Noble Gases in A-Level Chemistry.

    ERIC Educational Resources Information Center

    Marchant, G. W.

    1983-01-01

    Suggests two methods of developing the study of the noble gases: first, the discovery of the elements and recent discovery of xenon show the human face of chemistry (historical development); second, the properties of noble gas compounds (particularly xenon) can be used to test the framework of conventional chemistry. (Author/JM)

  5. REMOVAL OF TITAN'S ATMOSPHERIC NOBLE GASES BY THEIR SEQUESTRATION IN SURFACE CLATHRATES

    SciTech Connect

    Mousis, Olivier; Picaud, Sylvain [Universite de Franche-Comte, Institut UTINAM, CNRS/INSU, UMR 6213, Observatoire des Sciences de l'Univers de Besancon (France); Lunine, Jonathan I. [CRSR, Cornell University, Ithaca, NY 14853 (United States); Cordier, Daniel [Universite de Rennes 1, Institut de Physique de Rennes, CNRS, UMR 6251 (France); Mandt, Kathleen E. [Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX 78228 (United States); Hunter Waite, J. Jr., E-mail: olivier.mousis@obs-besancon.fr

    2011-10-10

    A striking feature of the atmosphere of Titan is that no heavy noble gases other than argon were detected by the Gas Chromatograph Mass Spectrometer aboard the Huygens probe during its descent to Titan's surface in 2005 January. Here we provide an explanation of the mysterious absence or rarity of these noble gases in Titan's atmosphere: the thermodynamic conditions prevailing at the surface-atmosphere interface of the satellite allow the formation of multiple guest clathrates that preferentially store some species, including all heavy noble gases, over others. The clean water ice needed for the formation of these clathrates could be delivered by successive episodes of cryovolcanic lavas that have been hypothesized to regularly cover the surface of Titan. The formation of clathrates in the porous lavas and their propensity for trapping Ar, Kr, and Xe would progressively remove these species from the atmosphere of Titan over the course of its history. In some circumstances, a global clathrate crust with an average thickness not exceeding a few meters could be sufficient on Titan for a complete removal of the heavy noble gases from the atmosphere.

  6. Photosensitive dopants for liquid noble gases

    DOEpatents

    Anderson, David F. (Wheaton, IL)

    1988-01-01

    In an ionization type detector for high energy radiation wherein the energy of incident radiation is absorbed through the ionization of a liquid noble gas and resulting free charge is collected to form a signal indicative of the energy of the incident radiation, an improvement comprising doping the liquid noble gas with photosensitive molecules to convert scintillation light due to recombination of ions, to additional free charge.

  7. Seawater subduction controls the heavy noble gas composition of the mantle.

    PubMed

    Holland, Greg; Ballentine, Chris J

    2006-05-11

    The relationship between solar volatiles and those now in the Earth's atmosphere and mantle reservoirs provides insight into the processes controlling the acquisition of volatiles during planetary accretion and their subsequent evolution. Whereas the light noble gases (helium and neon) in the Earth's mantle preserve a solar-like isotopic composition, heavy noble gases (argon, krypton and xenon) have an isotopic composition very similar to that of the modern atmosphere, with radiogenic and (in the case of xenon) solar contributions. Mantle noble gases in a magmatic CO2 natural gas field have been previously corrected for shallow atmosphere/groundwater and crustal additions. Here we analyse new data from this field and show that the elemental composition of non-radiogenic heavy noble gases in the mantle is remarkably similar to that of sea water. We challenge the popular concept of a noble gas 'subduction barrier'--the convecting mantle noble gas isotopic and elemental composition is explained by subduction of sediment and seawater-dominated pore fluids. This accounts for approximately 100% of the non-radiogenic argon and krypton and 80% of the xenon. Approximately 50% of the convecting mantle water concentration can then be explained by this mechanism. Enhanced recycling of subducted material to the mantle plume source region then accounts for the lower ratio of radiogenic to non-radiogenic heavy noble gas isotopes and higher water content of plume-derived basalts. PMID:16688169

  8. Seawater subduction controls the heavy noble gas composition of the mantle

    NASA Astrophysics Data System (ADS)

    Holland, Greg; Ballentine, Chris J.

    2006-05-01

    The relationship between solar volatiles and those now in the Earth's atmosphere and mantle reservoirs provides insight into the processes controlling the acquisition of volatiles during planetary accretion and their subsequent evolution. Whereas the light noble gases (helium and neon) in the Earth's mantle preserve a solar-like isotopic composition, heavy noble gases (argon, krypton and xenon) have an isotopic composition very similar to that of the modern atmosphere, with radiogenic and (in the case of xenon) solar contributions. Mantle noble gases in a magmatic CO2 natural gas field have been previously corrected for shallow atmosphere/groundwater and crustal additions. Here we analyse new data from this field and show that the elemental composition of non-radiogenic heavy noble gases in the mantle is remarkably similar to that of sea water. We challenge the popular concept of a noble gas `subduction barrier'-the convecting mantle noble gas isotopic and elemental composition is explained by subduction of sediment and seawater-dominated pore fluids. This accounts for ~100% of the non-radiogenic argon and krypton and 80% of the xenon. Approximately 50% of the convecting mantle water concentration can then be explained by this mechanism. Enhanced recycling of subducted material to the mantle plume source region then accounts for the lower ratio of radiogenic to non-radiogenic heavy noble gas isotopes and higher water content of plume-derived basalts.

  9. Noble Gases in Martian Meteorites: A Puzzle of Components, Sources, Pathways and Sinks

    NASA Astrophysics Data System (ADS)

    Schwenzer, S. P.; Ott, U.

    2014-11-01

    Noble gases have been measured on Mars by Viking and Curiosity, and studying them in meteorites revealed atmospheric and fractionated atmospheric signatures and possibly an inhomogeneous interior. But...terrestrial air has noble gases, too.

  10. Composition of noble gases in the Abee meteorite and the origin of the enstatite chondrites

    Microsoft Academic Search

    J. F. Wacker

    1982-01-01

    The Abee enstatite chrondite breccia was studied using two methods: measurement of noble gases, and, analyses of the clast size-distribution and the overall texture of Abee. These studies were made in order to understand the formation of the Abee breccia and the formation of the enstatite chrondrites. Noble gases were measured as a part of the consortium effort. Noble gases

  11. ChemTeacher: Noble Gases - Group 18 (VIIIA)

    NSDL National Science Digital Library

    2012-07-20

    ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Noble Gases page includes resources for teaching students about the discovery, properties and uses of the elements in Group 18.

  12. Impact degassing of water and noble gases from silicates

    NASA Technical Reports Server (NTRS)

    Azuma, S.; Hiyagon, H.; Iijima, Y.; Syono, Y.

    1994-01-01

    Previous shock experiments by Ahrens and his colleagues show that degassing of H2O and CO2 occurs at 8-65GPa from hydrous minerals such as serpentine. In early solar system, the impact degassing would have played an important part in the formation of primary-atmospheres of the terrestrial planets. However, degassing conditions of noble gases are not well-known because there are few experiments for them. We conducted some shock recovery experiments to investigate the degassing condition and to understand the degassing mechanisms of water and noble gases. We used natural richterites (Ri), amphibolites (Am), serpentines (Sep) and orthoclases (or) as target samples. These, except Sep, contain radiogenic noble gases such as (40)Ar. The samples were put in stainless steel containers, and were show by a rail gun at ISAS or single-stage powder guns at Nagoya or Tohoku University, Japan. We used two kinds of containers: 'open' type containers having a ventilating path for released volatiles for most of samples and 'closed' type ones for some samples for comparison. On Ri and Sep, we made shock experiments for pre-heated (at 400-500 C) and unheated targets, and for powdered and uncrushed samples. Water and noble gases were analyzed both for the recovered shocked samples and the unshocked original samples, and the fractions of the degassed volatiles were calculated by comparing them. Water content in the sample was analyzed by thermo-gravimetry. Noble gases were extracted by heating the samples under high vacuum and analyzed with a sector-type mass spectrometer.

  13. Experiments on thermal release of implanted noble gases from minerals and their implications for noble gases in lunar soil grains

    Microsoft Academic Search

    T. Futagami; M. Ozima; S. Nagai; Y. Aoki

    1993-01-01

    Experiments on ion implantation were performed in order to study the release mechanisms of solar particles from lunar soil grains. Helium, neon, and argon ions were implanted into olivine and ilmenite. The release temperatures of noble gases were investigated by heating samples stepwise; the results show that they depend on irradiation energy and dose. We conclude that the release temperature

  14. Nitrogen and light noble gases in Parsa enstatite chondrite

    NASA Technical Reports Server (NTRS)

    Murty, S. V. S.

    1993-01-01

    Solar gases have been recently reported in Parsa, an EH3 chondrite. In an effort to check whether solar gases are uniformly distributed throughout Parsa or they are located in specific phases, we analyzed two additional samples of bulk Parsa and one aubritic nodule for N and noble gases. Nitrogen studies are intended for the understanding of the nitrogen components distribution in E-chondrites. The N-systematics of the nodule are entirely different from the bulk samples. The higher N contents in this nodule, as well as its complex delta(sup 15)N structure, as compared to the normal aubrites, is suggestive that the nodule is not a genuine aubrite.

  15. Using noble gases to constrain gas exchange and biological productivity

    NASA Astrophysics Data System (ADS)

    Stanley, R.; Jenkins, W. J.; Lott, D. E.; Doney, S. C.

    2007-12-01

    The five noble gases (He, Ne, Ar, Kr, and Xe) are biologically and chemically inert, making them useful oceanographic tracers. Moreover, the noble gases have a wide range of solubilities and diffusivities, and thus respond differently to physical forcing. We present here a one year time-series of the five noble gases and the isotope 3He, measured in the upper 400 m of the Sargasso Sea with monthly resolution at the Bermuda Atlantic Time-series Site (BATS). Two profiles of the noble gases in the entire water column down to 4200 m are presented as well. We combine the upper ocean noble gas time-series data, nutrient, oxygen, and hydrographic data from BATS, and a one-dimensional vertical mixed layer model (a modified Price-Weller-Pinkel model) in order to quantify air-sea gas exchange processes. We use inverse modeling to quantify the magnitude of both diffusive gas exchange and air injection processes. The estimates obtained constrain the seasonal time-scale gas exchange rate to a precision of 6% and the bubble injection fluxes to 15%, valid for wind speeds up to 15 m/sec. The overall results suggest that the Wanninkhof quadratic formulation needs to be adjusted downward by approximately 20%. Additionally, 3He is used as a tracer of upwelling nutrients in order to constrain new production. Nutrients in the upper thermocline are well correlated with 3He, and thus 3He and nitrate measurements, combined with estimates of gas exchange, are used to quantify the input of new nutrients into the mixed layer. 3He measurement are also used in conjunction with tritium and oxygen data in order to calculate apparent oxygen utilization rates (AOUR) and thus to estimate export production.

  16. Seeded optically driven avalanche ionization in molecular and noble gases

    NASA Astrophysics Data System (ADS)

    Polynkin, Pavel; Pasenhow, Bernard; Driscoll, Nicholas; Scheller, Maik; Wright, Ewan M.; Moloney, Jerome V.

    2012-10-01

    We report experimental and numerical results on the dual laser-pulse plasma excitation in molecular and noble gases at atmospheric pressure. Dilute plasma channels generated through filamentation of ultraintense femtosecond laser pulses in air, argon, and helium are densified through the application of multijoule nanosecond heater pulses. Plasma densification in molecular gases is always accompanied by the fragmentation of the plasma channels into discrete bubbles, while in atomic gases, under certain conditions, the densified channels remain smooth and continuous. The densification effect in atomic gases persists through considerably longer delays between the femtosecond and nanosecond pulses compared to that in molecular gases. Using rate equations we trace this difference in the temporal dynamics of densification to the different cooling mechanisms operative in atomic and molecular cases.

  17. Nitrogen and light noble gases in Shergotty

    NASA Technical Reports Server (NTRS)

    Becker, R. H.; Pepin, R. O.

    1986-01-01

    Two samples of Shergotty and a sample of EETA 79001's lithology A have been analyzed for N, He, Ne, and Ar abundances and isotopic composition. After correcting for spallogenic nitrogen, the nitrogen isotopic ratios were found to be close to that of the terrestrial atmosphere. The spallogenic noble gas data are consistent with cosmic ray irradiation of both Shergotty and EETA 79001 at shallow shielding depths. Cosmic ray exposure ages were estimated to be in the range of 0.5-0.8 Myr for EETA 79001, and of 2.0-5.2 Myr for Shergotty, depending on the choice of object size and shielding. Among the two Shergotty samples, the contents of Ar-40 differed by a factor of 3. This difference can be attributed to either a small-scale mineralogical inhomogeneity or a significant variation in the degree of degassing of minerals during shock, although the presence of trapped argon with a high Ar-40/Ar-36 ratio and its heterogeneous distribution cannot be ruled out.

  18. Sorption of noble gases by solids, with reference to meteorites. II - Chromite and carbon. III - Sulfides, spinels, and other substances; on the origin of planetary gases

    NASA Technical Reports Server (NTRS)

    Yang, J.; Anders, E.

    1982-01-01

    The trapping of noble gases by chromite and carbon, two putative carriers of primordial noble gases in meteorites, was studied by synthesizing 19 samples in a Ne-Ar-Kr-Xe atmosphere at 440-720 K. Noble gas contents are found to approximately obey Henry's Law, but only slight correlations are found with composition, surface area, or adsorption temperature. Geometric mean distribution coefficients for bulk samples and HCl residues in 10 cu cm STP/g atm are: Xe 100, Kr 15, Ar 3.5, and Ne 0.62. Elemental fractionation data support the suggestion of Lewis et al. (1977) that chromite and carbon in C2 and C3 chondrites were formed by the reaction: Fe, Cr + 4CO yields (Fe, Cr)3O4 + 4C + carbides. In contrast to meteoritic minerals, the synthetic specimens show no isotopic fractionation of noble gases. In a subsequent study, attention is given to the cases of sulfides and spinels, on the way to consideration of the origin of planetary gases. Sulfides showed three distinctive trends relative to chromite or magnetite. The elemental fractionation pattern of Ar, Kr and Xe in meteorites, terrestrial rocks and planets resembles the adsorption patterns on the carbons, spinels, sulfides, and other solids studied. The high release temperature of meteoritic noble gases may be explained by transformation of the physisorbed or chemisorbed gas. The ready loss of meteoritic heavy gases on surficial oxidation is consistent with adsorption, as is the high abundance.

  19. Noble gases in CH 4-rich gas fields, Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Hiyagon, H.; Kennedy, B. M.

    1992-04-01

    The elemental and isotopic compositions of helium, neon, argon, and xenon in twenty-one CH 4-rich natural gas samples from Cretaceous and Devonian reservoirs in the Alberta, Canada, sedimentary basin were measured. In all but a few cases, radiogenic ( 4He, 40Ar, and 131-136Xe) and nucleogenic ( 21,22Ne) isotopes dominated. Based solely on the noble gas composition, two types of natural gas reservoirs are identified. One (Group B) is highly enriched in radiogenic-nucleogenic noble gases and varies little in composition: 3He /4He = 1.5 ± 0.5 × 10 -8, 40Ar /36Ar = 5000-6500 , 40?Ar /4He = 0.10 , 136?Xe /4He ~ 0.7 × 10 -9, and 21?Ne /22?Ne = 0.452 ± 0.041 (? denotes radiogenic or nucleogenic origin; all 4He is radiogenic). High nitrogen content with 4He /N 2 ~ 0.06 is also characteristic of Group B samples. The remaining samples (Group A) contain a radiogenic-nucleogenic component with a different composition and, relative to Group B samples, the extent of enrichment in this component is less and more variable: 3He /4He = 10-70 × 10 -8, 40Ar /36Ar < 1550 , and 40?Ar /4He ~ 0.25 . The composition of Group B radiogenic-nucleogenic noble gases is consistent with production in crust of average composition. Enrichment in Group B noble gases and nitrogen increases with proximity to the underlying Precambrian basement, consistent with a present-day mass flux into the overlying sedimentary basin. Inferred 40?Ar /136?Xe 4He ratios imply a basement source enriched in thorium relative to uranium and potassium (Th/U > 20). Combined, the overall lower total radiogenic-nucleogenic content of Group A reservoirs, the greater variability in composition, and the appearance of Group A noble gases in reservoirs higher in the sedimentary sequence relative to the underlying basement implies that the Group A radiogenic-nucleogenic noble gases are indigenous to the sediments. The most interesting aspect of the Group A noble gases are the very high 3He /4He ratios; ~ 10-70 times greater than expected if derived from average crust. The mantle, surface cosmogenic 3He production, cosmic dust, or production in a lithium-enriched environment as potential sources for the 3He excesses are evaluated. The present data set would seem to rule out cosmogenic 3He. The mantle, cosmic dust, or high Li, however, remain viable candidates. The relative abundances of the nonradiogenic, non-nucleogenic noble gases show no correlation with the Group A-B reservoir classification. Compositional variations indicate three-component mixing between air or an air-like component, 10°C air-saturated water, and a third component enriched in xenon. Apparently, the latter cannot be derived from equilibrium solubility degassing of air-saturated water or oil-water mixtures, and may have been derived from devolatilization of C-rich petroleum source sediments.

  20. Contraction of the positive column of discharges in noble gases

    NASA Astrophysics Data System (ADS)

    Golubovskii, Yu B.; Nekuchaev, V.; Gorchakov, S.; Uhrlandt, D.

    2011-10-01

    This review describes the experimental studies of contraction in neon, argon and helium, discussing the basic regularities of the phenomenon. These studies, extended over a long time, are still urgent. For pressures that are not too high a noticeable contraction of the plasma glow and a smooth non-monotonic dependence of the degree of contraction on the current are observed. Above a critical pressure the plasma immediately contracts into a bright thin cord, if the current reaches a critical value. A hysteresis phenomenon is observed during the transition from the diffuse state to the contracted state and vice versa. Experiments that show the secondary role of non-homogeneous gas heating for contraction in neon and argon, and the main role for contraction in helium, are described. Studies of the ionization waves (the strata), which propagate as pulses of the current cord area, are reviewed showing the close relationship between contraction and stratification. The roles of various mechanisms leading to the contraction and describing the general picture of the observed phenomena are analysed. For heavy noble gases the main role is played by ionization non-linearity as a function of electron concentration, which is related to the competition of electron-atom and electron-electron collisions. This non-linearity leads to plasma shrinkage and the development of ionization instability in the radial (contraction) and longitudinal (stratification) directions. For helium such non-linearity does not play a leading role, since the frequency of the elastic electron-atom collisions is considered to be constant over a large energy range, and this yields a Maxwellian distribution function. The contraction in helium is defined by thermal effects. In addition, recent studies on the numerical modelling of the contraction are discussed.

  1. Howardite Noble Gases as Indicators of Asteroid Surface Processing

    NASA Technical Reports Server (NTRS)

    Cartwright, J. A.; Mittlefehldt, D. W.; Herrin, J. S.; Ott, U.

    2011-01-01

    The HED (Howardite, Eucrite and Diogenite) group meteorites likely or iginate from the Asteroid 4 Vesta - one of two asteroid targets of NA SA's Dawn mission. Whilst Howardites are polymict breccias of eucriti c and diogenitic material that often contain "regolithic" petrologica l features, neither their exact regolithic nature nor their formation processes are well defined. As the Solar Wind (SW) noble gas compon ent is implanted onto surfaces of solar system bodies, noble gas anal yses of Howardites provides a key indicator of regolithic origin. In addition to SW, previous work by suggested that restricted Ni (300-12 00 micro g/g) and Al2O3 (8-9 wt%) contents may indicate an ancient we ll-mixed regolith. Our research combines petrological, compositional and noble gas analyses to help improve understanding of asteroid reg olith formation processes, which will play an intergral part in the i nterpretation of Dawn mission data. Following compositional and petrological analyses, we developed a regolith grading scheme for our sampl e set of 30 Howardites and polymict Eucrites. In order to test the r egolith indicators suggested by, our 8 selected samples exhibited a r ange of Ni, Al2O3 contents and regolithic grades. Noble gas analyses were performed using furnace stepheating on our MAP 215-50 noble gas mass spectrometer. Of our 8 howardites, only 3 showed evidence of SW noble gases (e.g approaching Ne-20/Ne-22 approximately equals 13.75, Ne-21/Ne-22 approximately equals 0.033). As these samples display low regolithic grades and a range of Ni and Al2O3 contents, so far we are unable to find any correlation between these indicators and "regolit hic" origin. These results have a number of implications for both Ho wardite and Vesta formation, and may suggest complex surface stratigr aphies and surface-gardening processes.

  2. Electron-photon coincidence study of heavy-noble-gas excitation at small scattering angles

    Microsoft Academic Search

    K. E. Martus; S.-H. Zheng; K. Becker

    1991-01-01

    The electron-polarized-photon coincidence technique has been used to study the finer details of the excitation of the first excited states of the heavy noble gases neon, argon, and krypton by electron impact in the regime of large impact parameters (small scattering angles and intermediate impact energies). Measurements with higher statistical accuracy of the P1 coherence parameter in forward scattering for

  3. Nitrogen and Noble Gases in Mineral Separates from Zagami

    NASA Astrophysics Data System (ADS)

    Schwenzer, S. P.; Mohapatra, R. K.; Herrmann, S.; Ott, U.

    2002-01-01

    Isotopic compositions of nitrogen and noble gases have played a key role in understanding SNC meteorites and Mars. For example nitrogen and argon data from the glass of EET 79001 were one of the convincing evidences that linked these meteorites to Mars. Similarly, the observation of components with largely different isotopic compositions (of both nitrogen and noble gases in these meteorites has led to the realization that the martian atmosphere (as measured by Viking) is quite different from the martian interior (as pictured from data from these meteorites). But at the same time we have not yet been able to clearly define the (interior) mantle end member and reduce the uncertainties presented by the Viking data for the martian atmosphere. Similarly we do not know for sure the Ne-20/Ne-22 signature of Mars. It is clear that many of these ambiguities as to the indigenous martian components result from interferences from cosmogenic contributions and terrestrial contamination, which are impossible to avoid. But they can be minimized by step temperature heating, and selection of mineral phases rather than bulk samples. We have initiated a simultaneous nitrogen and noble gas isotopic study of mineral separates and a few bulk samples from martian meteorites with the newly set up experimental facility at Mainz. Here we report data for maskelynite and pyroxene separates from Zagami.

  4. Heterogeneous distribution of solar and cosmogenic noble gases in CM chondrites and implications for the formation of CM parent bodies

    NASA Astrophysics Data System (ADS)

    Nakamura, Tomoki; Nagao, Keisuke; Metzler, Knut; Takaoka, Nobuo

    1999-01-01

    Distribution of solar, cosmogenic, and primordial noble gases in thin slices of Murchison, Murray, and Nogoya CM carbonaceous chondrites was determined by the laser microprobe analysis so as to put some constraints on the parent-body processes in the CM chondrite formation. The main lithological units of the three meteorite slices were located by electron microscope observations and classified into clastic matrix and clasts of primary accretionary rocks (PARs) based on the classification scheme of texture of CM chondrites. All sample slices contain both clastic matrix and PARs. Clastic matrix shows a comminuted texture formed by fragmentation and mechanical mixing of rocks due to impacts, whereas PARs preserve the original textures prior to the mechanical disruption. Solar-type noble gases are detected in all sample slices. They are located preferentially in clastic matrix. The distribution of solar gases is similar to that in ordinary chondrites where these gases reside in clastic dark portions of these meteorites. The heterogeneous distribution of solar gases in CM chondrites suggests that these gases were acquired not in a nebular accretion process but in parent body processes. Solar energetic particles (SEP) are predominant in CM chondrites. The low abundance of low energy solar wind (SW) component relative to SEP suggests preferential loss of SW from minerals comprising the clastic matrix, due to aqueous alteration in the parent bodies. Cosmogenic noble gases are also enriched in some portions in clastic matrix, indicating that some parts of clastic matrix were exposed to solar and galactic cosmic rays prior to the final consolidation of the CM parent bodies. Primordial noble gases are rich in fine-grained rims around chondrules in all three meteorites. However, average concentrations of heavy primordial gases in the rims differ among meteorites and correlate inversely to the degree of aqueous alteration that the meteorites have experienced. This appears to have been caused by aqueous alteration reactions between fluids and carbonaceous carrier phases of noble gases.

  5. On the siting of noble gases in E-chondrites

    NASA Technical Reports Server (NTRS)

    Crabb, J.; Anders, E.

    1982-01-01

    Fractions of six E-chondrites were separated by density, grain size, and chemical resistance to determine the siting of noble gases. The samples were taken from the Qingzhen (E3), Indarch (E4), Abee and Saint Saveur (E4-5), and Yilmia and North West Forrest (E6) meteorites. The Ar-rich component of the E6s was concentrated in the enstatite-rich fraction. This subsolar component was resistant to HCl and HNO3 treatment, but could be partially dissolved by HF, implying that the subsolar component is located in the enstatite. The noble gases were transported there by metamorphism. Xe-129 was found in the same regions in the E6s, but was in areas associated with chondrules in the E4s. Additionally, the carbon-rich fraction of the E4 sample displayed Xe and Ne/CCF-Xe isotopic ratios similar to that found in C-chondrites. E3 and E4 primordial gases were analogous, with no subsolar contribution.

  6. Effect of Noble Gases on Sonoluminescence Temperatures during Multibubble Cavitation

    SciTech Connect

    Didenko, Yuri T.; McNamara, William B. III; Suslick, Kenneth S.

    2000-01-24

    Sonoluminescence spectra were collected from Cr(CO){sub 6} solutions in octanol and dodecane saturated with various noble gases. The emission from excited-state metal atoms serves as an internal thermometer of cavitation. The intensity and temperature of sonoluminescence increases from He to Xe. The intensity of the underlying continuum, however, grows faster with increasing temperature than the line emission. Dissociation of solvent molecules within the bubble consumes a significant fraction of the energy generated by the collapsing bubble, which can limit the final temperature inside the bubble. (c) 2000 The American Physical Society.

  7. Noble gases and radiocarbon in natural gas hydrates

    NASA Astrophysics Data System (ADS)

    Winckler, Gisela; Aeschbach-Hertig, Werner; Holocher, Johannes; Kipfer, Rolf; Levin, Ingeborg; Poss, Christian; Rehder, Gregor; Suess, Erwin; Schlosser, Peter

    2002-05-01

    In samples of pure natural gas hydrates from Hydrate Ridge, Cascadia Margin, virtually no helium and neon components are present providing evidence that the light noble gases are not incorporated into the structure of natural methane hydrates. In contrast, the hydrates contain significant amounts of argon, krypton and xenon. These gases show a distinct fractionation pattern, with the heavier ones preferentially incorporated into the gas hydrate structure. The hydrate methane is devoid of 14C indicating that there is no contribution of a recent (14C-active) organic carbon reservoir to the hydrate carbon pool. On the basis of the ?13C and ?2H signature, it appears that microbial CO2-reduction is the dominant CH4 production pathway.

  8. Solar composition noble gases in the Washington County iron meteorite

    NASA Technical Reports Server (NTRS)

    Becker, R. H.; Pepin, R. O.

    1984-01-01

    A sample of the Washington County iron meteorite is analyzed for its light noble gases by a combustion technique in two steps at 1160 C. The ratio of trapped to spallogenic noble gases in the sample was high enough to allow the resolution of trapped and spallogenic components in both combustion steps. The He:Ne:Ar elemental ratios in the trapped component are comparable to present-day solar-wind ratios. The (Ne-20)/(Ne-22) ratio, while subject to some uncertainty due to possible variation in either the spallation or the trapped component between the two steps, is in the range 13.3 + or 0.5, also comparable to present-day solar wind. Unless the Washington County iron formed by some unique process in a solar-wind-irradiated regolith, the fact that the trapped gas is of solar composition has implications with regard to the compositional history of the solar wind, to conditions in the early solar nebula during grain formation or accretion, and to primordial helium in the earth.

  9. Solubilities of nitrogen and noble gases in basalt melt

    NASA Technical Reports Server (NTRS)

    Miyazaki, A.; Hiyagon, H.; Sugiura, N.

    1994-01-01

    Nitrogen and noble gases are important tracers in geochemistry and chosmochemistry. Compared to noble gases, however, physicochemical properties of nitrogen, such as solubility in melt or melt/silicate partition, are not well known. Solubility of nitrogen in basalt melt depends on redox condition of the atmosphere. For example, solubility of nitrogen in E chondrite melt under reducing conditions is as high as 2 mol percent at 1500 C, suggesting that nitrogen is chemically dissolved in silicate melts, i.e., being dissolved as free anions or replacing oxygen sites in silicate network. However, the solubility and the dissolution mechanism of nitrogen under oxidizing conditions are not well investigated. To obtain nitrogen solubility in silicate melts under various redox conditions and to understand its mechanism, we are conducting experiments by using (15)N(15)N-labeled nitrogen gas. This makes it easy to distinguish dissolved nitrogen from later contamination of atmospheric nitrogen, and hence enables us to measure the nitrogen solubility accurately. As a preliminary experiment, we have measured solubility of nitrogen in basalt melt under the atmospheric oxygen pressure.

  10. Microdistribution of primordial noble gases in CM chondrites determined by in situ laser microprobe analysis: Decipherment of nebular processes

    NASA Astrophysics Data System (ADS)

    Nakamura, Tomoki; Nagao, Keisuke; Takaoka, Nobuo

    1999-01-01

    In situ noble gas analyses using a laser microprobe with a beam diameter of 50-100 ?m were performed on thin slices of Murchison and Yamato (Y-) 791198 CM carbonaceous chondrites in order to see microdistribution of primordial noble gases. Petrographic observations prior to noble-gas analyses showed that the two meteorite slices are entirely composed of chondrules, PCPs (poorly characterized phases) and other chondritic components that are rimmed by layers of fine-grained dust. Based on an existing classification scheme for texture of CM chondrites, the two samples are classified as primary accretionary rocks (PARs). The noble gas analyses showed that primordial noble gases are rich in the fine-grained rims around chondrules in the two meteorite slices. This suggests that large amounts of carrier phases of the primordial noble gases in CM chondrites are located in these rims which seem to have accreted on the surfaces of chondrules prior to the formation of the meteorite parent bodies. Rims on different chondrules within a given meteorite showed similar concentrations of heavy primordial noble gases, suggesting that phase Q is distributed homogeneously in the rims and possibly in the nebular region where the chondrules had acquired their dust rims. ( 20Ne) diamond/( 20Ne) Q ratios are relatively constant among rims in a given meteorite, indicative of homogeneous mixing of interstellar diamonds and phase Q on a 10 ?g scale. One location in a rim around a chondrule in the Murchison sample showed an enrichment of 22Ne, which suggests presence of carrier phases of Ne-E in the rim. A stepped heating analysis of a chip of Y-791198 was carried out to characterize the noble gases of bulk PAR. Abundances of primordial noble gases are only ˜50% of those of rims around chondrules, consistent with the relative abundances of gas-rich fine-grained material and gas-poor chondrules and inclusions in PAR. Solar gases were not detected, which implies that PARs, the primitive CM bodies, had grown to at least centimeter size in a dense solar nebula which shielded these objects from direct exposure to solar wind.

  11. Solubilities of noble gases in magnetite - Implications for planetary gases in meteorites.

    NASA Technical Reports Server (NTRS)

    Lancet, M. S.; Anders, E.

    1973-01-01

    Solubilities of noble gases in magnetite were determined by growing magnetite in a noble-gas atmosphere between 450 and 700 K. Henry's law is obeyed at pressures up to .01 atm for He, Ne, Ar and up to .00001 atm for Kr, Xe, with the following distribution coefficients at 500 K: He 0.042, Ne 0.016, Ar 3.6, Kr 1.3, Xe 0.88, some 100 to 100,000 times higher than previous determinations on silicate and fluoride melts. Apparent heats of solution are in sharp contrast with earlier determinations on melts which were small and positive, but are comparable to the values for clathrates. Presumably the gases are held in anion vacancies.

  12. Chemical composition of Titan's lakes and noble gases sequestration

    NASA Astrophysics Data System (ADS)

    Cordier, D.; Mousis, O.; Lunine, J.-I.; Lavvas, P.; Lobo, L.; Ferreira, A.

    2010-04-01

    Titan is one of the most enigmatic objects in the Solar System. The presence of hydrocarbon lakes and even a global ocean have been suspected for decades. The dark features discovered by the CASSINI spacecraft are good candidates for these expected lakes (see McEwen et al. 2005 and Stofan et al. 2007). Their chemical composition has still not been measured but numerical models can give relatively accurate predictions. In the present work, we use the recent model of Titan's lakes chemical composition elaborated by Cordier et al. (2009) in light of the recent Cassini-Huygens measurements in order to investigate the possibility of sequestration of large quantities of noble gases in these liquids. Indeed, the noble gas abundances have been found to be largely in subsolar abundances in the atmosphere of Titan and the origin of this impoverishment is still poorly understood. Our preliminary results show that, under specific circumstances, at least the atmospheric depletion in krypton could be caused by its dissolution in the Titan's surface hydrocarbon liquid phase.

  13. WIMP Dark Matter Direct-Detection Searches in Noble Gases

    E-print Network

    Laura Baudis

    2014-08-19

    Cosmological observations and the dynamics of the Milky Way provide ample evidence for an invisible and dominant mass component. This so-called dark matter could be made of new, colour and charge neutral particles, which were non-relativistic when they decoupled from ordinary matter in the early universe. Such weakly interacting massive particles (WIMPs) are predicted to have a non-zero coupling to baryons and could be detected via their collisions with atomic nuclei in ultra-low background, deep underground detectors. Among these, detectors based on liquefied noble gases have demonstrated tremendous discovery potential over the last decade. After briefly introducing the phenomenology of direct dark matter detection, I will review the main properties of liquefied argon and xenon as WIMP targets and discuss sources of background. I will then describe existing and planned argon and xenon detectors that employ the so-called single- and dual-phase detection techniques, addressing their complementarity and science reach.

  14. Noble gases and cosmogenic radionuclides in the Eltanin Pacific meteorite

    SciTech Connect

    Bogard, D D; Garrison, D H; Caffee, M W; Kyte, F; Nishiizumi, K

    2000-01-14

    A 1.5 cm long, 1.2 g specimen of the Eltanin meteorite was found at 10.97 m depth in Polarstern piston core PS2704-1. The early studies indicated that the small fragments of the Eltanin meteorite was debris from a km-sized asteroid which impacted into the deep-ocean basin. In this study, the authors measured {sup 39}Ar-{sup 40}Ar age, noble gases, and cosmogenic radionuclides in splits of specimen as a part of consortium studies of Eltanin meteorite. They concluded that the specimen was about 3 m deep from the asteroid surface. The exposure age of the Eltanin asteroid was about 20 Myr.

  15. WIMP dark matter direct-detection searches in noble gases

    NASA Astrophysics Data System (ADS)

    Baudis, Laura

    2014-09-01

    Cosmological observations and the dynamics of the Milky Way provide ample evidence for an invisible and dominant mass component. This so-called dark matter could be made of new, colour and charge neutral particles, which were non-relativistic when they decoupled from ordinary matter in the early universe. Such weakly interacting massive particles (WIMPs) are predicted to have a non-zero coupling to baryons and could be detected via their collisions with atomic nuclei in ultra-low background, deep underground detectors. Among these, detectors based on liquefied noble gases have demonstrated tremendous discovery potential over the last decade. After briefly introducing the phenomenology of direct dark matter detection, I will review the main properties of liquefied argon and xenon as WIMP targets and discuss sources of background. I will then describe existing and planned argon and xenon detectors that employ the so-called single- and dual-phase detection techniques, addressing their complementarity and science reach.

  16. Solar Noble Gases in Polymict Ureilites and an Update on Ureilite Noble Gas Data

    NASA Astrophysics Data System (ADS)

    Ott, U.; Lohr, H. P.; Begemann, F.

    1993-07-01

    Ureilites are one of the least understood classes of meteorites; they show signs of being processed, but also appear to be primitive, with abundant carbon and trapped noble gases [1-6]. We have now begun to analyze a number of recently recovered specimens: one from the Saharan desert (Acfer 277) amd five from the Antarctic (LEW 85328, LEW 85440, EET 87720, FRO 90036, and FRO 90054). Analyses of Acfer 277, LEW 85328, and EET 87720 are complete (Table 1). Solar noble gases are present in polymict EET 87720, as shown by the three- isotope plot of Fig. 1. There, in contrast to the bulk data point for Acfer 277, data points for EET 87720 deviate from a mixing line between "typical" spallation Ne (as approximated here by the spallation-dominated 1800 degrees C step for EET 87720) and Ne-U [7] toward higher ^20Ne/^22Ne. A line fitted to the EET 87720 data points passes slightly below Ne-B [8]. The situation is similar for sample F1 from polymict EET 83309 [9], which is shown for comparison. Additional support for the presence of solar gases arises from the abundance of ^4He (~9 x 10^-5 cm^3 STP/g in EET 87720-F1, corrected for spallogenic contributions), which in both cases is far higher than in other ureilite bulk samples [6,10]. Also, in the ratio of spallation-corrected ^4He to trapped ^36Ar, these two polymict ureilites clearly stand out. Helium-4/argon-36 ratios in EET 87720-F1 and EET 83309-F1 are ~20 and ~28 respectively, at least 1 order of magnitude higher than in bulk monomict ureilites and 2 orders of magnitude higher than what appears typical of ureilite diamonds [6]. Nilpena, another polymict ureilite [11], also has a ^4He/^36Ar ratio (2.1 in Nilpena II-1 [7]) higher than all monomict ureilites but one (Dingo Pup Donga), indicating the presence of solar noble gases (in variable contents) as a possible general feature of polymict ureilites, similar to the presence in them of nitrogen with high delta(^15N/^14N) [12]. Monomict LEW 85328 has a very high (^22Ne/^21Ne)(sub)c ratio of the cosmogenic component, indicative of irradiation under very low shielding conditions, but otherwise abundances and abundance ratios for the momomict ureilites LEW 85328 and Acfer 277 appear quite "ordinary" when compared to other monomict ureilites [6,10]. References: [1] Wasson J. T. et al. (1976) GCA, 40, 1449-1458. [2] Berkley J. L. et al. (1980) GCA, 44, 1579-1597. [3] Takeda H. (1989) EPSL, 93, 181- 194. [4] Warren P. H. and Kallemeyn G. W. (1989) Meteoritics, 24, 233-246. [5] Clayton R. N. and Mayeda T. K. (1988) GCA, 52, 1313-1318. [6] Gobel R. et al. (1978) JGR, 83, 855-867. [7] Ott U. et al. (1984) Meteoritics, 19, 287-288. [8] Black D. C. (1972) GCA, 36, 347-375. [9] Ott U. et al. (1990) Meteoritics, 25, 396. [10] Schultz L. and Kruse H. (1989) Meteoritics, 24, 155-172. [11] Jaques A. L. and Fitzgerald M. J. (1982) GCA, 46, 893-900. [12] Grady M. M. and Pillinger C. T. (1988) Nature, 331, 321-323. Table 1, which appears here in the hard copy, shows noble gases in monomict ureilites Acfer 277 and LEW 85328 and polymict ureilite EET 87720. Fig. 1 appears here in the hard copy.

  17. Highly Concentrated Nebular Noble Gases in Porous Nanocarbon Separates from the Saratov (L4) Meteorite

    NASA Astrophysics Data System (ADS)

    Amari, Sachiko; Matsuda, Jun-ichi; Stroud, Rhonda M.; Chisholm, Matthew F.

    2013-11-01

    The majority of heavy noble gases (Ar, Kr, and Xe) in primitive meteorites are stored in a poorly understood phase called Q. Although Q is thought to be carbonaceous, the full identity of the phase has remained elusive for almost four decades. In order to better characterize phase Q and, in turn, the early solar nebula, we separated carbon-rich fractions from the Saratov (L4) meteorite. We chose this meteorite because Q is most resistant in thermal alteration among carbonaceous noble gas carriers in meteorites and we hoped that, in this highly metamorphosed meteorite, Q would be present but not diamond: these two phases are very difficult to separate from each other. One of the fractions, AJ, has the highest 132Xe concentration of 2.1 × 10-6 cm3 STP g-1, exceeding any Q-rich fractions that have yet been analyzed. Transmission electron microscopy studies of the fraction AJ and a less Q-rich fraction AI indicate that they both are primarily porous carbon that consists of domains with short-range graphene orders, with variable packing in three dimensions, but no long-range graphitic order. The relative abundance of Xe and C atoms (6:109) in the separates indicates that individual noble gas atoms are associated with only a minor component of the porous carbon, possibly one or more specific arrangements of the nanoparticulate graphene.

  18. Underground Nuclear Explosions and Release of Radioactive Noble Gases

    NASA Astrophysics Data System (ADS)

    Dubasov, Yuri V.

    2010-05-01

    Over a period in 1961-1990 496 underground nuclear tests and explosions of different purpose and in different rocks were conducted in the Soviet Union at Semipalatinsk and anovaya Zemlya Test Sites. A total of 340 underground nuclear tests were conducted at the Semipalatinsk Test Site. One hundred seventy-nine explosions (52.6%) among them were classified as these of complete containment, 145 explosions (42.6%) as explosions with weak release of radioactive noble gases (RNG), 12 explosions (3.5%) as explosions with nonstandard radiation situation, and four excavation explosions with ground ejection (1.1%). Thirty-nine nuclear tests had been conducted at the Novaya Zemlya Test Site; six of them - in shafts. In 14 tests (36%) there were no RNG release. Twenty-three tests have been accompanied by RNG release into the atmosphere without sedimental contamination. Nonstandard radiation situation occurred in two tests. In incomplete containment explosions both early-time RNG release (up to ~1 h) and late-time release from 1 to 28 h after the explosion were observed. Sometimes gas release took place for several days, and it occurred either through tunnel portal or epicentral zone, depending on atmospheric air temperature.

  19. Noble Gases in Two Fragments of Different Lithologies from the Almahata Sitta Meteorite

    NASA Technical Reports Server (NTRS)

    Nagao, K.; Haba, M. K.; Zolensky, M.; Jenniskens, P.; Shaddad, M. H.

    2014-01-01

    The Almahata Sitta meteorite, whose preat-mospheric body was the asteroid 2008 TC3, fell on October 7, 2008 in the Nubian Desert in northern Sudan [e.g., 1, 2]. Numer-ous fragments have been recovered during several expeditions organized from December 2008 [2]. The meteorite was classified as an anomalous polymict ureilite with several different kinds of chondritic fragments [e.g., 3-5]. Noble gas studies performed on several fragments from the meteorite showed cosmic-ray expo-sure ages of about 20 My [e.g., 6-8], although slightly shorter ages were also reported in [9, 10]. Concentrations of trapped heavy noble gases are variable among the fragments of different lithologies [9, 10]. We report noble gas data on two samples from the #1 and #47 fragments [2], which were the same as those re-ported by Ott et al. [9]. Experimental Procedure: Weights of bulk samples #1 and #47 used in this work were 16.1 mg and 17.6 mg, respectively. Noble gases were extracted by stepwise heating at the tempera-tures of 800, 1200 and 1800°C for #1 and 600, 800, 1000, 1200, 1400, 1600 and 1800°C for #47. Concentrations and isotopic ra-tios of noble gases were measured with a modified-VG5400/MS-III at the Geochemical Research Center, University of Tokyo. Results and Discussion: Cosmogenic He and Ne are domi-nant in both #1 and #47, but trapped Ar, Kr and Xe concentra-tions are much higher in #47 than in #1, showing that noble gas compositions in #47 are similar to those of ureilites. 3He/21Ne and 22Ne/21Ne of cosmogenic He and Ne are 4.8 and 1.12 for #1 and 3.6 and 1.06 for #47, respectively, both of which plot on a Bern line [11]. This indicates negligible loss of cosmogenic 3He from #1 in our sample, unlike the low 3He/21Ne of 3.1 for #1 by Ott et al. [9]. Concentrations of cosmogenic 3He and 21Ne (10-8 cc/g) are 30 and 6.3 for #1 and 32 and 9.0 for #47, respectively, which are higher than those in [9] and give cosmic-ray exposure ages of ca. 20 My depending on assumed production rates. Rela-tive abundances of trapped 36Ar, 84Kr and 132Xe for #1 resemble those of Q-component, which is a dominant trapped noble gas component in chondrites. In contrast to #1, #47 plots below a trend for ureilites [12] as well as Q, which implies a partial loss of trapped 36Ar from the lithology of #47.

  20. Depth Profiles of Cosmogenic Noble Gases in the Chondrite Knyahinya

    NASA Astrophysics Data System (ADS)

    Toe, S.; Lavielle, B.; Gilabert, E.; Simonoff, G. N.

    1993-07-01

    Concentrations and isotopic ratios of Ne, Ar, Kr, and Xe have been analyzed in 5-g size samples from different positions within the L5 chondrite Knyahinya. A previous work [1] has shown that Knyahinya experienced a single-stage exposure history (duration 40.5 Ma) as a meteoroid of approximately spherical shape (radius 45 cm). For these reasons, this meteorite represents a very interesting object to study depth profiles of cosmogenic nuclide concentrations and to test and improve model calculations of production rates. The procedure of extraction of noble gases adopted for this work, includes two pyrolyses respectively at about 450 degrees C and 650 degrees C, followed by a combustion step in pure O2 (15-25 torr pressure) at 650 degrees C before the complete melting of the sample [2]. This procedure allows a low-temperature extraction of a significant fraction of the Kr and Xe trapped noble gas component, leading to an enrichment of the cosmogenic component during the last temperature step. Concentration of trapped Ar, Kr, and Xe is 2-3 times lower than expected for a type 5 chondrite. The isotopic composition of the trapped Xe component analyzed in the combustion step is identical with the OC- Xe composition measured in Forest Vale [3]. Preliminary results show that concentration of cosmogenic 83Kr increases by 16% from the surface to the center when the ratio of cosmogenic 78Kr to 83Kr decreases from 0.157 to 0.136. The concentration of 81Kr has been measured in each sample. It increases from 0.0220 10^-12 cm^3 STP/g near the surface to 0.0255 10^-12 cm^3 STP/g at the center, in excellent agreement with the variations measured by Eugster [4] in other ordinary chondrites. Acknowledgments: This work was supported by C.N.R.S., by IN2P3 and by INSU (Programme National de Planetologie). References: [1] Graf Th. et al. (1990) GCA, 54, 2511-2520. [2] Gilabert E. and Lavielle B. (1991) Meteoritics, 26, 337. [3] Lavielle B. and Marti K. (1992) JGR, 97, 20875-20881. [4] Eugster O. (1988) GCA, 52, 1649-1662.

  1. Mantle-derived noble gases in natural gases from Songliao Basin, China

    NASA Astrophysics Data System (ADS)

    Xu, Sheng; Nakai, Shun'ichi; Wakita, Hiroshi; Wang, Xianbin

    1995-11-01

    Abundances and isotopic compositions of noble gases have been measured in six natural gas samples (CO 2 and CH 4-rich) from the Songliao Basin, Jilin Province, in northeastern China. The samples contain noble gases of mantle origin. The 3He/4He ratio reaches 5.0 times the atmospheric ratio. In a three-isotope plot of neon, the 20Ne/22Ne (up to 10.9) and 21Ne/22Ne (up to 0.051) ratios make a positive correlation array together with natural gases from other continental areas. Compared with a correlation band for MORB, the natural gases have a lower slope with more nucleogenic 21Ne. The natural gas samples contain radiogenic argon with 40Ar/36Ar ratios up to 7700. A positive correlation between 40Ar/36Ar and 20Ne/22Ne ratios indicates occurrence of mantle-derived Ar. Slight excess of 38Ar can be attributed to a nuclear reaction like 35C1 (?, p) 38 Ar. Apparent excesses of 1292'Xe, 132-136Xe are recognized in four samples. The excess of 129Xe (up to 3%) can be attributed to a decay of extinct 129I. Excess 132-136Xe is not large enough to determine if the origin of the excess is 238U or 244Pu. Anomaly in 129Xe/130Xe ratio is correlated with that of 136Xe/130Xe. The isotopic features of the natural gases with radiogenic 4He and nucleogenic 21Ne can be produced within the crust. Alternatively, they may reflect the geochemical features of the subcontinental mantle which has been enriched in U, Th. We can not distinguish the two possibilities. However, a natural gas from another basin in eastern China with a different reservoir age contains mantle derived neon which falls on the neon correlation line formed by the samples from the Songliao Basin. This consistency suggests that the isotopic features of the natural gases aren't necessarily ascribable to surface contamination of radiogenic and nucleogenic isotopes.

  2. Solar wind noble gases and nitrogen in metal from lunar soil 68501

    NASA Technical Reports Server (NTRS)

    Becker, Richard H.; Pepin, Robert O.

    1994-01-01

    Noble gases and N were analyzed in handpicked metal separates from lunar soil 68501 by a combination of step-wise combustions and pyrolyses. Helium and Ne were found to be unfractionated with respect to one another when normalized to solar abundances, for both the bulk sample and for all but the highest temperature steps. However, they are depleted relative to Ar, Kr and Xe by at least a factor of 5. The heavier gases exhibit mass-dependent fractionation relative to solar system abundance ratios but appear unfractionated, both in the bulk metal and in early temperature steps, when compared to relative abundances derived from lunar ilmenite 71501 by chemical etching, recently put forward as representing the abundance ratios in solar wind. Estimates of the contribution of solar energetic particles (SEP) to the originally implanted solar gases, derived from a basic interpretation of He and Ne isotopes, yield values of about 10%. Analysis of the Ar isotopes requires a minimum of 20% SEP, and Kr isotopes, using our preferred composition for solar wind Kr, yield a result that overlaps both these values. It is possible to reconcile the data from these gases if significant loss of solar wind Ar, Kr and presumably Xe has occurred relative to the SEP component, most likely by erosive processes that are mass independent, although mass-dependent losses (Ar greater than Kr greater than Xe) cannot be excluded. If such losses did occur, the SEP contribution to the solar implanted gases must have been no more than a few percent. Nitrogen is a mixture of indigenous meteoritic N, whose isotopic composition is inferred to be relatively light, and implanted solar N, which has probably undergone diffusive redistribution and fractionation. If the heavy noble gases have not undergone diffusive loss, then N/Ar in the solar wind can be inferred to be at least several times the accepted solar ratio. The solar wind N appears, even after correction for fractionation effects, to have a minimum delta N-15 value equal to or greater than +150% and a more probable value equal to or greater than +200%.

  3. A Mass Spectrometric System for the Analysis of Noble Gases and

    E-print Network

    Aeschbach-Hertig, Werner

    , setup, and performance of a mass spectrometric system for the analysis of noble gas isotopes (3He, 4He spectrometers. We present a new approach for the analysis of the heavy noble gas isotopes that enables isotopes of He, Ne, Ar, Kr, Xe and the hydrogen isotope tritium are widely used as environmental tracers

  4. Noble Gases in Two Fragments of Different Lithologies from the Almahata Sitta Meteorite

    NASA Astrophysics Data System (ADS)

    Nagao, K.; Haba, M. K.; Zolensky, M.; Jenniskens, P.; Shaddad, M. H.

    2014-09-01

    We report noble gas data on #1 and #47 fragments from the Almahata Sitta meteorite which is an anomalous polymict ureilite with several different kinds of chondritic fragments. Cosmic-ray exposure ages and trapped heavy noble gas compositions will be presented.

  5. Tracing a past thermal event by using atmospheric noble gases dissolved in deep Michigan Basin brines

    NASA Astrophysics Data System (ADS)

    Ma, L.; Castro, M. C.; Hall, C. M.

    2008-12-01

    Atmospheric noble gases (e.g., 22Ne, 36Ar, 84Kr, 130Xe) are introduced into the subsurface by recharge water in solubility equilibrium with the atmosphere (Air Saturated Water - ASW). Because noble gases are chemically inert and stable in nature, they are only sensitive to subsurface physical processes. More specifically, depletion of this component in sedimentary systems commonly suggests loss to an oil or natural gas phase in the subsurface, which is originally free of atmospheric noble gases. This has been traditionally used to identify and quantify subsurface oil, gas, and water phase interactions. Alternatively, depletion of atmospheric noble gases due to subsurface boiling and steam phase separation has also been previously recorded in tectonically active areas (hydrothermal systems). Such depletion is thus indicative of the occurrence of a thermal event and can be used to trace the thermal history of stable tectonic regions. Here, we present noble gas concentrations of 38 deep brines (~0.5-3.6km) from the Michigan Basin. The atmospheric noble gas component shows a strong depletion pattern with respect to air saturated water. Depletion of lighter gases (22Ne and 36Ar) is stronger compared to the heavier ones (84Kr and 130Xe). To understand the mechanisms responsible for this overall atmospheric noble gas depletion, phase interaction models were tested. We show that this atmospheric noble gas depletion pattern is best explained by a model involving subsurface boiling and steam separation, and thus, consistent with the occurrence of a past thermal event of mantle origin as previously indicated by both high 4He/heat flux ratios and the presence of primordial mantle He and Ne signatures in the basin. Such a conceptual model is also consistent with the presence of past elevated temperatures in the Michigan Basin (e.g., ~80- 260°C) at shallow depths as suggested by previous thermal studies in the basin. We suggest that recent reactivation of the ancient mid-continent rift system underneath the Michigan Basin is likely responsible for the release of both heat and mantle noble gases into the basin via deep-seated faults and fracture zones. Relative enrichment of atmospheric Kr and Xe with respect to Ar is also observed, and is interpreted as reflecting the addition of sedimentary Kr and Xe from associated hydrocarbons, following the hydrothermal event. This study pioneers the use of atmospheric noble gases in subsurface fluids to trace the thermal history of stable tectonic regions.

  6. Methane activation using noble gases in a dielectric barrier discharge reactor

    SciTech Connect

    Jo, Sungkwon; Hoon Lee, Dae; Seok Kang, Woo; Song, Young-Hoon [Korea Institute of Machinery and Materials, 156 Gajeongbuk-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of)] [Korea Institute of Machinery and Materials, 156 Gajeongbuk-ro, Yuseong-gu, Daejeon 305-343 (Korea, Republic of)

    2013-08-15

    The conversion of methane is measured in a planar-type dielectric barrier discharge reactor using three different noble gases—He, Ne, and Ar—as additives. The empirical results obtained clearly indicate that methane activation is considerably affected by thy type of noble gas used. Through 0-D calculations, the discharge parameters inside the reactor, i.e., electron temperature and electron density, are estimated using experiment results. A comparison of the discharge characteristics and experimental results shows that the electron temperature is an important factor in achieving high methane activation and the mixture with Ar gas shows the highest methane conversion. These results are constructed using the mechanisms of energy and charge transfer from excited and ionized noble gas atoms to methane molecules, considering the number density of active atoms of noble gases. Finally, electron temperatures obtained for gas mixtures having different reactant compositions and concentrations are analyzed to estimate methane activation.

  7. Infiltration of river water to a shallow aquifer investigated with 3H\\/ 3He, noble gases and CFCs

    Microsoft Academic Search

    U. Beyerle; W. Aeschbach-Hertig; M. Hofer; D. M Imboden; H Baur; R Kipfer

    1999-01-01

    Noble gas isotopes (3He, 4He, Ne, Ar, Kr, Xe), tritium (3H), chlorofluorocarbons (CFCs) and dissolved oxygen (O2) were seasonally measured in a small groundwater system recharged by infiltration of river water at Linsental, northeastern Switzerland. All Groundwater samples contained an excess of atmospheric noble gases (‘excess air’) usually with an elemental composition equal to air. The concentrations of atmospheric noble

  8. Dynamics of a geothermal field traced by noble gases: Cerro Prieto, Mexico

    SciTech Connect

    Mazor, E. (Weizmann Inst. of Science, Rehovot, Israel); Truesdell, A.H.

    1981-01-01

    Noble gases have been measured mass spectrometrically in samples collected during 1977 from producing wells at Cerro Prieto. Positive correlations between concentrations of radiogenic (He, /sup 40/Ar) and atmospheric noble gases (Ne, Ar, and Kr) suggest the following dynamic model: the geothermal fluids originated from meteoric water penetrated to more than 2500 m depth (below the level of first boiling) and mixed with radiogenic helium and argon-40 formed in the aquifer rocks. Subsequently, small amounts of steam were lost by a Raleigh process (0 to 3%) and mixing with shallow cold water occurred (0 to 30%). Noble gases are sensitive tracers of boiling in the initial stages of 0 to 3% steam separation and complement other tracers, such as Cl or temperature, which are effective only beyond this range.

  9. Growth Responses of Neurospora crassa to Increased Partial Pressures of the Noble Gases and Nitrogen

    PubMed Central

    Buchheit, R. G.; Schreiner, H. R.; Doebbler, G. F.

    1966-01-01

    Buchheit, R. G. (Union Carbide Corp., Tonawanda, N.Y.), H. R. Schreiner, and G. F. Doebbler. Growth responses of Neurospora crassa to increased partial pressures of the noble gases and nitrogen. J. Bacteriol. 91:622–627. 1966.—Growth rate of the fungus Neurospora crassa depends in part on the nature of metabolically “inert gas” present in its environment. At high partial pressures, the noble gas elements (helium, neon, argon, krypton, and xenon) inhibit growth in the order: Xe > Kr> Ar ? Ne ? He. Nitrogen (N2) closely resembles He in inhibitory effectiveness. Partial pressures required for 50% inhibition of growth were: Xe (0.8 atm), Kr (1.6 atm), Ar (3.8 atm), Ne (35 atm), and He (? 300 atm). With respect to inhibition of growth, the noble gases and N2 differ qualitatively and quantitatively from the order of effectiveness found with other biological effects, i.e., narcosis, inhibition of insect development, depression of O2-dependent radiation sensitivity, and effects on tissue-slice glycolysis and respiration. Partial pressures giving 50% inhibition of N. crassa growth parallel various physical properties (i.e., solubilities, solubility ratios, etc.) of the noble gases. Linear correlation of 50% inhibition pressures to the polarizability and of the logarithm of pressure to the first and second ionization potentials suggests the involvement of weak intermolecular interactions or charge-transfer in the biological activity of the noble gases. PMID:5883104

  10. Noble Gases in the Terrestrial Planets, with Focus on What the SNC Meteorites Tell Us About Mars

    NASA Astrophysics Data System (ADS)

    Pepin, R. O.

    2002-01-01

    Noble gases in the solar wind and giant-planet atmospheres are generally assumed to be the best "perhaps the only" available proxies for isotopic distributions in the early solar nebula. Both, however, may be isotopically fractionated to some degree from their source composition, the wind in processes that transport solar plasma to and release it from the corona, and giant-planet Ar, Kr and Xe by trapping in icy planetesimals if these were indeed the principal suppliers of heavy noble gases to their present atmospheres. Noble gas isotopic ratios in the solar wind are reasonably well established from lunar and asteroidal regolith studies and the Galileo Probe mass spectrometer has given us our first look at compositions in Jupiter's atmosphere. Modern theories of atmospheric evolution on the terrestrial planets are focused on the nebula as the primary supplier of primordial planetary volatiles, either directly -i.e., in ways that do not fractionate isotopes (by adsorption on planetary embryos or "ingassing" from dense, gravitationally condensed atmospheres)- or by accretion of cometary ices carrying noble gases that could have been either isotopically solar or mildly fractionated during trapping from the ambient nebula. The observation that nonradiogenic Ne, Ar, Kr and Xe in Earth's current atmosphere are all isotopically heavier than their solar counterparts is an important clue to the nature of the processes that subsequently acted on these primordial planetary reservoirs. This is also the case on Mars, except for Kr which is isotopically near-solar (and therefore an interesting challenge for evolutionary modeling), and on Venus as well, as far as one can tell from the limited data on hand.

  11. Method and apparatus for measuring purity of noble gases

    SciTech Connect

    Austin, Robert (Largo, FL)

    2008-04-01

    A device for detecting impurities in a noble gas includes a detection chamber and a source of pulsed ultraviolet light. The pulse of the ultraviolet light is transferred into the detection chamber and onto a photocathode, thereby emitting a cloud of free electrons into the noble gas within the detection chamber. The cloud of electrons is attracted to the opposite end of the detection chamber by a high positive voltage potential at that end and focused onto a sensing anode. If there are impurities in the noble gas, some or all of the electrons within the cloud will bond with the impurity molecules and not reach the sensing anode. Therefore, measuring a lower signal at the sensing anode indicates a higher level of impurities while sensing a higher signal indicates fewer impurities. Impurities in the range of one part per billion can be measured by this device.

  12. Anomalous depth profiles of light ions and noble gases implanted into polymers

    NASA Astrophysics Data System (ADS)

    Guimarães, R. B.; Amaral, L.; Behar, M.; Zawislak, F. C.; Fink, D.

    1989-03-01

    We report on a depth profile study of 6Li and noble gases implanted into the AZ111 photoresist. The measured profiles of 6Li confirm previous data for light ions (B and F) showing that above a threshold implantation energy part of the implanted ions redistribute according to the TRIM calculated ionization profile. The noble gases Ar, Kr and Xe have shown noticeable diffusion after room temperature implantation. Two regimes of diffusional behaviour were observed corresponding to the damaged and non-damaged regions of the polymer. The diffusion in the damaged region strongly depends on fluence showing a behaviour similar to that of resistivity in ion irradiated polymers.

  13. Liquid scintillation counting of polycarbonates: a sensitive technique for measurement of activity concentration of some radioactive noble gases.

    PubMed

    Mitev, K; Zhivkova, V; Pressyanov, D; Georgiev, S; Dimitrova, I; Gerganov, G; Boshkova, T

    2014-11-01

    This work explores the application of the liquid scintillation counting of polycarbonates for measurement of the activity concentration of radioactive noble gases. Results from experimental studies of the method are presented. Potential applications in the monitoring of radioactive noble gases are discussed. PMID:24559941

  14. Seeded optical breakdown of molecular and noble gases

    NASA Astrophysics Data System (ADS)

    Polynkin, Pavel; Scheller, Maik; Moloney, Jerome V.

    2012-07-01

    We report experimental results on the dual laser-pulse plasma excitation in various gases at atmospheric pressure. Dilute plasma channels generated through filamentation of ultraintense femtosecond laser pulses in air, argon, and helium are densified through the application of multi-Joule nanosecond heater pulses. Optical breakdown in atomic gases can be achieved for considerably longer delays between femtosecond and nanosecond pulses compared to that in molecular gases. The densification of the seed channel in molecular gases is always accompanied by its fragmentation into discrete bubbles, while in atomic gases the densified channel remains smooth and continuous.

  15. On the origin of noble gases in mantle plumes.

    PubMed

    Coltice, Nicolas; Ricard, Yanick

    2002-11-15

    The chemical differences between deep- and shallow-mantle sources of oceanic basalts provide evidence that several distinct components coexist within the Earth's mantle. Most of these components have been identified as recycled in origin. However, the noble-gas signature is still a matter of debate and questions the preservation of primitive regions in the convective mantle. We show that a model where the noble-gas signature observed in Hawaii and Iceland comes from a pristine homogeneous deep layer would imply a primitive (3)He content and (3)He/(22)Ne ratio that are very unlikely. On the contrary, mass balances show that the partly degassed peridotite of a marble-cake mantle can be the noble-gas end-member with an apparent 'primitive'-like composition. This component is mixed with recycled oceanic crust in different proportions in the plume sources and in the shallow mantle. A recycling model of the mantle, involving gravitational segregation of the oceanic crust at the bottom of the mantle, potentially satisfies trace-element as well as noble-gas constraints. PMID:12460484

  16. Primordial noble gases from Earth's mantle: identification of a primitive volatile component

    PubMed

    Caffee; Hudson; Velsko; Huss; Alexander; Chivas

    1999-09-24

    Carbon dioxide well gases in Colorado, New Mexico, and South Australia show excesses of (124-128)Xe correlated with (129)I-derived (129)Xe and (20)Ne/(22)Ne ratios that are higher than the atmospheric (20)Ne/(22)Ne ratio. The xenon isotopic data indicate the presence of a solarlike component deep within Earth. The presence of this component in crustal and upper mantle reservoirs may be explained by a steady-state transport of noble gases from the lower mantle, which still retains much of its juvenile volatile inventory. These measurements also indicate that the mantle source of these noble gases in the carbon dioxide well gases cannot be the source of Earth's present atmosphere. The variations observed in (129)Xe/(130)Xe between solar wind xenon, Earth's atmosphere, and mantle samples may be generated by variations of iodine/xenon in terrestrial reservoirs, as opposed to rapid early degassing. PMID:10497127

  17. Analytical partitioning of total cross sections for electron scattering on noble gases

    Microsoft Academic Search

    Roberto S. Brusa; Grzegorz P. Karwasz; Antonio Zecca

    1996-01-01

    Empirical analytical formulae are proposed, aiming at the description of partial cross sections for electron scattering on noble gases. Selected measurements of total, excitation and ionization cross sections for these gases have been fitted by these analytical formulae in the 20-5000reV energy range. The elastic cross sections, obtained as the difference, compare quite well with the elastic experimental data for

  18. Noble gases and the early history of the Earth: Inappropriate paradigms and assumptions inhibit research and communication

    NASA Technical Reports Server (NTRS)

    Huss, G. R.; Alexander, E. C., Jr.

    1985-01-01

    The development of models as tracers of nobel gases through the Earth's evolution is discussed. A new set of paradigms embodying present knowledge was developed. Several important areas for future research are: (1) measurement of the elemental and isotopic compositions of the five noble gases in a large number of terrestrial materials, thus better defining the composition and distribution of terrestrial noble gases; (2) determinations of relative diffusive behavior, chemical behavior, and the distribution between solid and melt of noble gases under mantle conditions are urgently needed; (3) disequilibrium behavior in the nebula needs investigation, and the behavior of plasmas and possible cryotrapping on cold nebular solids are considered.

  19. Fractionation of noble gases by thermal escape from accreting planetesimals

    NASA Technical Reports Server (NTRS)

    Donahue, T. M.

    1986-01-01

    Assuming solar initial elemental and isotopic ratios and a determination of the degree of fractionation occurring by competition between gravitational binding and escape, a model is developed for selective noble gas loss through escape during the growth of planetesimals to form the terrestrial planets. Of the two classes of planetesimals that can form on a time scale that is consistent with modern accretion models, one is depleted in neon while the other is neon-rich. The mechanism is noted to be capable of accounting for all known properties of the noble gas volatiles on the terrestrial planets, with only one exception, namely the Ar-36/Ar-38 ratios for Mars and the earth, which are much lower than observed.

  20. The determination of accurate dipole polarizabilities alpha and gamma for the noble gases

    NASA Technical Reports Server (NTRS)

    Rice, Julia E.; Taylor, Peter R.; Lee, Timothy J.; Almlof, Jan

    1991-01-01

    Accurate static dipole polarizabilities alpha and gamma of the noble gases He through Xe were determined using wave functions of similar quality for each system. Good agreement with experimental data for the static polarizability gamma was obtained for Ne and Xe, but not for Ar and Kr. Calculations suggest that the experimental values for these latter ions are too low.

  1. Preserving noble gases in a convecting mantle Helge M. Gonnermann1

    E-print Network

    Mukhopadhyay, Sujoy

    mantle. As a result, even when the mass flux across the 660-km seismic discontinuity is equivalentLETTERS Preserving noble gases in a convecting mantle Helge M. Gonnermann1 & Sujoy Mukhopadhyay2 undegassedlower-mantle reservoir with high 3 He concentrations1­4 . A large and mostly undegassed mantle reservoir

  2. The record of cosmogenic, radiogenic, fissiogenic, and trapped noble gases in recently recovered Chinese and other chondrites

    NASA Astrophysics Data System (ADS)

    Eugster, O.; Michel, Th.; Niedermann, S.; Wang, D.; Yi, W.

    1993-03-01

    Noble-gas isotopic abundances were determined in 36 recently recovered chondrites including 27 chondrites recovered in China. The comparison of the release patterns of trapped noble gases from ordinary and from carbonaceous chondrites showed that the planetary trapped noble gases in ordinary chondrites were released mainly above 1200 C, whereas more than 85 percent of noble gases trapped in carbonaceous chondrites were released at or below 1200 C, indicating that the carrier phases of the trapped noble gases in ordinary and in carbonaceous chondrites may not be the same. It is suggested that the ordinary chondrites started to retain fission Xe about 48 +/- 30 Ma earlier than Angra dos Reis. No systematic differences were observed between H, L, and LL or type 5 and 6 chondrites with respect to the time of fission Xe retention. Eight chondrites displayed neutron capture effects due to secondary cosmic-ray-produced neutrons.

  3. Noble gases in twenty Yamato H-chondrites: Comparison with Allan Hills chondrites and modern falls

    NASA Technical Reports Server (NTRS)

    Loeken, TH.; Scherer, P.; Schultz, L.

    1993-01-01

    Concentration and isotopic composition of noble gases have been measured in 20 H-chrondrites found on the Yamato Mountains ice fields in Antarctica. The distribution of exposure ages as well as of radiogenic He-4 contents is similar to that of H-chrondrites collected at the Allan Hills site. Furthermore, a comparison of the noble gas record of Antarctic H-chrondrites and finds or falls from non-Antarctic areas gives no support to the suggestion that Antarctic H-chrondrites and modern falls derive from differing interplanetary meteorite populations.

  4. Elastic Properties of Films of Water and Noble Gases Condensed at Low Temperatures

    NASA Technical Reports Server (NTRS)

    Pohl, Robert O.

    2003-01-01

    We have shown that there are extensive similarities between the quench-condensed noble gas films and those of amorphous water ice. In particular, both can be quite soft upon deposition and can stiffen considerably when annealed. Furthermore, this stiffening follows a logarithmic time dependence for all substances. The temperature dependence of these behaviors scales with the triple point. The results shown here show a strong thickness dependence, which has implications for any study of mechanical properties of films on substrates. The temperature dependence of the stiffening and the stiffening rate have now been characterized for the noble gases, and these observations provide a roadmap for new experiments on amorphous water ice.

  5. Spectral line broadening of atoms by noble gases

    NASA Astrophysics Data System (ADS)

    Demura, A. V.; Umanskii, S. Ya; Scherbinin, A. V.; Zaitsevskii, A. V.

    2012-12-01

    The complex universal approach for calculations of the binary broadening of atomic spectral lines by buffer noble gas atoms is presented. The interatomic interaction is described on the basis of the Buckingham potential, parameterized with the help of ab initio electron modeling. The Unified Frank-Condon Theory is used for the calculations of the total line profile. For the first time the impact limit is determined exactly using the Van der Waals long-range tail of the potential and taking into account the degeneracy of quasimolecular states but neglecting non-adiabatic effects. The general asymptotic wings dependences of the profile are established for the Buckingham parameterized potential. The receipts of the wings cut-offs are formulated for the approximate but sufficiently accurate evaluation of the total line profile using only the Van der Waals part of potential to be applied in large scale calculations of radiative transfer.

  6. Laser-Polarized Noble Gases: From Basic Science to Medical Applications

    NASA Astrophysics Data System (ADS)

    Cates, Gordon D.

    2002-03-01

    Noble gases, whose nuclei have been polarized by spin exchange with optically pumped alkali-metal atoms, provide valuable research opportunities. The polarization process itself involves a rich host of phenomena which even after many years is still providing surprises. The applications of polarized noble gases, both in basic research and in applied areas, are growing in number. For instance, polarized ^3He targets, used in accelerator experiments, have been instrumental in elucidating the internal spin structure of the nucleon. Also, since the mid 1990's, polarized ^3He and ^129Xe have been used in a new type of magnetic resonance imaging in which the patient breaths the noble gas, and the magnetization of the nuclei is used to produce images of the gas space of the lungs. The technique has moved from early demonstration experiments into the process of commercialization. The talk will begin by describing the basic physics of spin-exchange optical pumping, and will proceed to cover various applications. Particular emphasis will be given to noble-gas imaging, the process of its commercialization, and the accompanying issues that face a university researcher.

  7. Nuclear magnetic resonance of laser-polarized noble gases in molecules, materials and organisms

    SciTech Connect

    Goodson, Boyd M.

    1999-12-01

    Conventional nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) are fundamentally challenged by the insensitivity that stems from the ordinarily low spin polarization achievable in even the strongest NMR magnets. However, by transferring angular momentum from laser light to electronic and nuclear spins, optical pumping methods can increase the nuclear spin polarization of noble gases by several orders of magnitude, thereby greatly enhancing their NMR sensitivity. This dissertation is primarily concerned with the principles and practice of optically pumped nuclear magnetic resonance (OPNMR). The enormous sensitivity enhancement afforded by optical pumping noble gases can be exploited to permit a variety of novel NMR experiments across many disciplines. Many such experiments are reviewed, including the void-space imaging of organisms and materials, NMR and MRI of living tissues, probing structure and dynamics of molecules in solution and on surfaces, and zero-field NMR and MRI.

  8. Initial results of noble gases in micrometeorites from the Transantarctic Mountains, Antarctica

    NASA Astrophysics Data System (ADS)

    Baecker, B.; Cordier, C.; Folco, L.; Trieloff, M.; Ott, U.

    2012-12-01

    The bulk of extraterrestrial matter collected by Earth is in the form of micrometeorites, which have a main flux onto Earth at about 220 ?m in diameter [1]. According to the petrographic and geochemical data, most of the small micrometeorites have been related to CM chondrites [2]. Recent studies suggest that larger micrometeorites (> 300?m) mostly derive from ordinary chondrite sources e.g. [3-5]. Following some models [6], they may have made important contributions to the volatile inventory of the Earth. We have initiated a coupled comprehensive survey of noble gas contents and petrography in micrometeorites. While helium and neon are generally dominated by the solar wind contribution, the inventory of heavy primordial noble gases has been hardly characterized so far. In particular, useful data are lacking on the diagnostic isotopic composition of xenon. We hope to fill this gap, since huge amounts of material are available. This might make a contribution towards understanding some aspects of the formation of the solar system and in particular the terrestrial atmosphere. We will present results obtained on "large" micrometeorites from Victoria Land, Transantarctic Mountains. These were collected during a PNRA (Programma Nazionale delle Ricerche in Antartide, Italy) expedition on top of the Miller Butte micrometeorite traps #45 b and c [7]. We reported first results in [8]. Our research includes however, also material from other collections, e.g. CONCORDIA [9, 10]. [1] Love, S.G., Brownlee, D.E. (1993) Science 262, 550-553. [2] Kurat, G. et al. (1994) Geochimica et Cosmochimica Acta 58, 3879-3904. [3] Genge, M.J. et al. (2008) Meteoritics & Planetary Science 43, 497-515. [4] Dobrica, E. et al. (2011) Meteoritics & Planetary Science 46, 1363-1375. [5] Van Ginneken M. et al. (2012) Meteoritics & Planetary Science 47, 228-247. [6] Maurette, M. et al. (2000) Planetary and Space Science 48, 1117-1137. [7] Rochette P. et al. (2008) Proceedings of the National Academy of Sciences , 105, 18206-18211. [8] Baecker B. et al. (2012) 43rd Lunar & Planetary Science Conference (abs. #1824). [9] Duprat J. et al. (2007) Advances in Space Research 39, 605-611. [10] Baecker B. et al. (2012) 75th Annual Meeting of the Meteoritical Society (abs. #5056).

  9. Cosmogenic 10Be and Noble Gases in Diogenites

    NASA Astrophysics Data System (ADS)

    Welten, K. C.; Lindner, L.; van der Borg, K.; Loeken, Th.; Scherer, P.; Schultz, L.

    1993-07-01

    Introduction: A recent reevaluation of the 3He, 21Ne, and 38Ar cosmic-ray exposure ages of eight non-Antarctic and three Antarctic diogenite falls led to a consistent set of exposure ages with a major cluster at 22 Ma and a possible second cluster around 40 Ma [1]. These clusters coincide with two major peaks in the exposure-age distributions of the genetically related eucrites and howardites [2], but the scarcity of young diogenites is remarkable [3]. An update of the exposure-age distribution for diogenites, including nine separate Antarctic falls, will be presented and possible differences in exposure history between Antarctic and non-Antarctic diogenites will be discussed. The exposure-age distributions of eucrites and howardites are still controversial [2,3], as conventional shielding corrections--on the basis of the 22Ne/21Ne ratio--cannot be applied. Therefore, the use of other shielding parameters, such as 10Be or 26Al, is considered. We examined the relation between 10Be contents and 22Ne/21Ne ratios in diogenites to obtain more insight into the shielding sensitivity of the 10Be production rate. Experimental: In addition to the existing database of more than 30 noble gas analyses [4] we carried out noble gas measurements on 5 non-Antarctic diogenites and on 12 Antarctic samples from 9 separate falls. On the same samples 10Be was measured by AMS. The experimental uncertainties in the 10Be values are 2-3%, those in the 22Ne/21Ne ratios are 0.5-1.0%. Results and Conclusions: The major exposure-age cluster at 22 Ma contains about 45% of the diogenite falls, indicating a major impact on its parent body. However, the presence of several younger diogenites suggests that this collisional event was not necessarily as destructive as previously suggested [3]. Four diogenites show exposure ages around 40 Ma, indicating a second major impact on the HED parent body. Although some Antarctic diogenites have unique mineralogical features [5,6], we didn't find any evidence for different populations on the basis of their exposure histories. Figure 1 shows the experimental relation between 10Be contents and 22Ne/21Ne ratios measured in diogenites. The 10Be contents decrease by 30-35%, while corresponding 22Ne/21Ne ratios increase from 1.07 to 1.29. Graf's semi- experimental model predicts--for L chondrites with preatmospheric radii less than 50 cm--a decrease of about 50% in 10Be over this interval of 22Ne/21Ne ratios [7]. This discrepancy cannot be explained by the minor differences in composition with respect to 10Be production. Therefore, our results indicate that this model is slightly overestimating the shielding sensitivity of 10Be. Five points do not fall within 2 sigma on the best (exponential) fit. Measurements of additional radionuclides may contribute to a better understanding of their outlying character. Acknowledgments: We thank the MWG in the USA, the NIPR in Tokyo and the National Museums for Natural History in Washington, London, and Paris for diogenite samples. This work was financially supported by the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO). References: [1] Welten K. C. et al. (1991) Meteoritics, 26, 408. [2] Schultz L. (1987) LPSC XVIII, 884-885. [3] Alymer D. et al. (1988) GCA, 52, 1691-1698. [4] Schultz L. and Kruse H. (1989) Meteoritics, 24, 155-172. [5] Takeda H. (1991) GCA, 55, 35-57. [6] Berkley J. L. and Boynton N. J. (1992) Meteoritics, 27, 387-394. [7] Graf Th. et al. (1990) GCA, 54, 2521-2534. Figure 1, which appears in the hard copy, shows shielding effects on P10 in diogenites.

  10. The role of van der Waals interactions in the adsorption of noble gases on metal surfaces

    SciTech Connect

    Chen, De-Li; Al-Saidi, W. A.; Johnson, J. Karl

    2012-10-24

    Adsorption of noble gases on metal surfaces is determined by weak interactions. We applied two versions of the nonlocal van der Waals density functional (vdW-DF) to compute adsorption energies of Ar, Kr, and Xe on Pt(111), Pd(111), Cu(111), and Cu(110) metal surfaces. We have compared our results with data obtained using other density functional approaches, including the semiempirical vdW corrected DFT-D2. The vdW-DF results show considerable improvements in the description of adsorption energies and equilibrium distances over other DFTbased methods, giving good agreement with experiments. We have also calculated perpendicular vibrational energies for noble gases on the metal surfaces using vdWDF data and found excellent agreement with available experimental results. Our vdW-DF calculations show that adsorption of noble gases on low-coordination sites is energetically favored over high-coordination sites, but only by a few meV. Analysis of the 2-dimensional potential energy surface shows that the high-coordination sites are local maxima on the 2-dimensional potential energy surface and therefore unlikely to be observed in experiments, which provides an explanation of the experimental observations. The DFT-D2 approach with the standard parameterization was found to overestimate the dispersion interactions, and to give the wrong adsorption site preference for four of the nine systems we studied.

  11. Nitrogen and noble gases in a glass sample from LEW88516

    NASA Technical Reports Server (NTRS)

    Becker, R. H.; Pepin, R. O.

    1993-01-01

    The Antarctic meteorite LEW88516 has been classified as a member of the SNC group of meteorites, specifically a shergottite. It is reported to be remarkably similar in mineralogy, petrogenesis and chemistry to the previously known ALH77005 shergottite, with both being compositionally distinct from other shergottites. LEW88516 shows pervasive shock features and has been found to contain glass veins attributable to a shock origin. In an effort to determine whether the glass in LEW88516 contains any of the isotopically-heavy trapped nitrogen component observed in EETA 79001 glass, as well as the related high-Ar-40/Ar-36 and high-Xe-129/Xe-132 components, we undertook an analysis of an 11.9 mg glass sample (LEW88516,4) provided to us by H. Y. McSween, Jr. as part of a consortium study of this meteorite. Nitrogen and noble gases were extracted from LEW88516,4 in a series of combustion steps at increasing temperatures followed by a final pyrolysis. Initial steps at 550 C were intended to remove any surface-sited nitrogen-containing contaminants, while the 700 C step was expected to show the onset of release of a trapped argon component, based on our previous data for EETA 79001. It was hoped that the bulk of any trapped gas release would be concentrated in one of two steps at 1100 C and approximately 1400 C, maximizing our analytical sensitivity. Results of the analysis are shown. Except for He and Ne, data obtained for the 550 C steps will be omitted from further consideration on the assumption that they represent terrestrial contamination.

  12. The solubility of noble gases in crude oil at 25-100??C

    USGS Publications Warehouse

    Kharaka, Y.K.; Specht, D.J.

    1988-01-01

    The solubility of the noble gases He, Ne, Ar, Kr and Xe was measured in two typical crude oils at temperatures of 25-100??C. The oil samples were obtained from the Elk Hills oil field located in southern San Joaquin Valley, California. The experimental procedure consisted of placing a known amount of gas with a known volume of crude oil in a stainless steel hydrothermal pressure vessel. The vessel was housed inside an oven and the entire unit rotates providing continuous mixing. The amount of gas dissolved in oil at a measured temperature and partial pressure of gas was used to calculate the solubility constants for these gases. Results show that the solubility of He and Ne in both oils is approximately the same; solubility then increases with atomic mass, with the solubility of Xe at 25??C being two orders of magnitude higher than that of He. The gas solubilities are somewhat higher in the lower density (higher API gravity) oil. The solubility of Ar is approximately constant in the range of temperatures of this study. The solubilities of He and Ne increase, but those of Kr and Xe decrease with increasing temperatures. Solubilities of noble gases in crude oil are significantly higher than their solubilities in water. For example, the solubilities of He and Xe at 25??C in the light oil of this study are, respectively, 3 and 24 times higher than their solubilities in pure water, and they are 15 and 300 times higher than in a brine with a salinity of 350,000 mg/l dissolved solids. These large and variable differences in the solubilities of noble gases in oil and water indicate that, in sedimentary basins with oil, these gases must be partitioned between oil, water and natural gas before they are used to deduce the origin and residence time of these fluids. ?? 1988.

  13. Noble gases as tracers of the origin and evolution of the Martian atmosphere and the degassing history of the planet

    NASA Technical Reports Server (NTRS)

    Swindle, T. D.

    1988-01-01

    Noble gas analysis of Martian samples can provide answers to a number of crucial questions. Some of the most obvious benefits will be in Martian chronology, using techniques that have been applied to lunar samples. However, these are by no means the only relevant noble gas studies possible. Since Mars has a substantial atmosphere, noble gases can be used to study the origin and evolution of that atmosphere, including the degassing history of the planet. This type of study can provide constraints on: (1) the total noble gas inventory of the planet, (2) the number of noble gas reservoirs existing, and (3) the exchange of gases between these reservoirs. How to achieve these goals are examined.

  14. GAS-PHASE SEQUESTRATION OF NOBLE GASES IN THE PROTOSOLAR NEBULA: POSSIBLE CONSEQUENCES ON THE OUTER SOLAR SYSTEM COMPOSITION

    SciTech Connect

    Pauzat, F.; Ellinger, Y.; Ozgurel, O. [Laboratoire de Chimie Théorique, UMR 7616-CNRS, UPMC Univ. Paris 06, F-75005 Paris (France); Mousis, O.; Ali Dib, M., E-mail: pauzat@lct.jussieu.fr, E-mail: ellinger@lct.jussieu.fr, E-mail: zge.zgerel@gmail.com, E-mail: olivier.mousis@obs-besancon.fr, E-mail: mdib@obs-besancon.fr [Institut UTINAM, CNRS/INSU, UMR 6213, Université de Franche-Comté, F-25030 Besançon Cedex (France)

    2013-11-01

    We address the problem of the sequestration of Ar, Kr, and Xe by H{sub 3}{sup +} in the gas-phase conditions encountered during the cooling of protoplanetary disks when H{sub 3}{sup +} is competing with other species present in the same environment. Using high-level ab initio simulations, we try to quantify other sequestration possibilities involving He, H{sub 5}{sup +}, H{sub 2}O, and H{sub 3}O{sup +} present in the protosolar nebula. Apart from the fact that H{sub 3}{sup +} complexes formed with heavy noble gases are found to be by far much more stable than those formed with He or H{sub 2}O, we show that H{sub 2}D{sup +} and H{sub 3}O{sup +}, both products of the reactions of H{sub 3}{sup +} with HD and H{sub 2}O, can also be efficient trapping agents for Ar, Kr, and Xe. Meanwhile, the abundance profile of H{sub 3}{sup +} in the outer part of the nebula is revisited with the use of an evolutionary accretion disk model that allows us to investigate the possibility that heavy noble gases can be sequestered by H{sub 3}{sup +} at earlier epochs than those corresponding to their trapping in planetesimals. We find that H{sub 3}{sup +} might be abundant enough in the outer protosolar nebula to trap Xe and Kr prior their condensation epochs, implying that their abundances should be solar in Saturn's current atmosphere and below the observational limit in Titan. The same scenario predicts that comets formed at high heliocentric distances should also be depleted in Kr and Xe. In situ measurements, such as those planed with the Rosetta mission on 67P/Churyumov-Gerasimenko, will be critical to check the validity of our hypotheses.

  15. Sorption of noble gases by solids, with reference to meteorites. I - Magnetite and carbon

    NASA Technical Reports Server (NTRS)

    Yang, J.; Lewis, R. S.; Anders, E.

    1982-01-01

    The trapping of meteoritic noble gases by solids is simulated through the synthesis of 18 Fe3O4 samples at 350-720 K in a noble gas atmosphere, by means of the reactions: (1) 3Fe + 4H2O yields Fe3O4 + 4H2, using Ne, Ar, Kr and Xe; and (2) 3Fe + 4CO yields Fe3O4 + 4C + carbides, using Xe. Etching experiments suggest an analogy with 'Phase Q' in meteorites. Adsorbed atmospheric gases are present in all samples, and dominate whenever the noble gas partial pressure in the atmosphere is greater than that in the synthesis. While many of the results of Lancet and Anders (1973) appear to have been dominated by such an atmospheric component, others are suspect. When the doubtful samples of Lancet and Anders are corrected or eliminated, the fractionation pattern no longer peaks at Ar, but rather, as in the present sample, rises monotonically from Ne to Xe. No evidence is found for the earlier study's claim of a strong temperature dependence.

  16. The five stable noble gases are sensitive unambiguous tracers of glacial meltwater

    NASA Astrophysics Data System (ADS)

    Loose, B.; Jenkins, W. J.

    2014-04-01

    The five inert noble gases—He, Ne, Ar, Kr, and Xe—exhibit a unique dissolved gas saturation pattern resulting from the formation and addition of glacial meltwater to seawater. He and Ne become oversaturated, and Ar, Kr, and Xe become undersaturated to varying percentages. For example, addition of 10‰ glacial meltwater to seawater results in a saturation anomaly of ?He = 12.8%, ?Ne = 8.9%, ?Ar = -0.5%, ?Kr = -2.2%, and ?Xe = -3.3%. This pattern in noble gas saturation reflects a unique meltwater signature that is distinct from the other major physical processes that modify the gas concentration and saturation, namely, seasonal changes in temperature at the ocean surface and bubble mediated gas exchange. We use Optimum Multiparameter analysis to illustrate how all five noble gases can help distinguish glacial meltwater from wind-driven bubble injection, making them a potentially valuable suite of tracers for glacial melt and its concentration in the deep waters of the world ocean.

  17. The origins and concentrations of water, carbon, nitrogen and noble gases on Earth

    NASA Astrophysics Data System (ADS)

    Marty, Bernard

    2012-01-01

    The isotopic compositions of terrestrial hydrogen and nitrogen are clearly different from those of the nebular gas from which the solar system formed, and also differ from most of cometary values. Terrestrial N and H isotopic compositions are in the range of values characterizing primitive meteorites, which suggests that water, nitrogen, and other volatile elements on Earth originated from a cosmochemical reservoir that also sourced the parent bodies of primitive meteorites. Remnants of the proto-solar nebula (PSN) are still present in the mantle, presumably signing the sequestration of PSN gas at an early stage of planetary growth. The contribution of cometary volatiles appears limited to a few percents at most of the total volatile inventory of the Earth. The isotope signatures of H, N, Ne and Ar can be explained by mixing between two end-members of solar and chondritic compositions, respectively, and do not require isotopic fractionation during hydrodynamic escape of an early atmosphere. The terrestrial inventory of 40Ar (produced by the decay of 40K throughout the Earth's history) suggests that a significant fraction of radiogenic argon may be still trapped in the silicate Earth. By normalizing other volatile element abundances to this isotope, it is proposed that the Earth is not as volatile-poor as previously thought. Our planet may indeed contain up to ~ 3000 ppm water (preferred range: 1000-3000 ppm), and up to ~ 500 ppm C, both largely sequestrated in the solid Earth. This volatile content is equivalent to an ~ 2 (± 1) % contribution of carbonaceous chondrite (CI-CM) material to a dry proto-Earth, which is higher than the contribution of chondritic material advocated to account for the platinum group element budget of the mantle. Such a (relatively) high contribution of volatile-rich matter is consistent with the accretion of a few wet planetesimals during Earth accretion, as proposed by recent dynamical models. The abundance pattern of major volatile elements and of noble gases is also chondritic, with two notable exceptions. Nitrogen is depleted by one order of magnitude relative to water, carbon and most noble gases, which is consistent with either N retention in a mantle phase during magma generation, or trapping of N in the core. Xenon is also depleted by one order of magnitude, and enriched in heavy isotopes relative to chondritic or solar Xe (the so-called "xenon paradox"). This depletion and isotope fractionation might have taken place due to preferential ionization of xenon by UV light from the early Sun, either before Earth's formation on parent material, or during irradiation of the ancient atmosphere. The second possibility is consistent with a recent report of chondritic-like Xe in Archean sedimentary rocks that suggests that this process was still ongoing during the Archean eon (Pujol et al., 2011). If the depletion of Xe in the atmosphere was a long-term process that took place after the Earth-building events, then the amounts of atmospheric 129Xe and 131-136Xe, produced by the short-lived radioactivities of 129I (T 1/2 = 16 Ma) and 244Pu (T 1/2 = 82 Ma), respectively, need to be corrected for subsequent loss. Doing so, the I-Pu-Xe age of the Earth becomes ? 50 Ma after start of solar system formation, instead of ~ 120 Ma as computed with the present-day atmospheric Xe inventory.

  18. Solar noble gases revealed by closed system stepped etching of a metal separate from Fayetteville

    NASA Technical Reports Server (NTRS)

    Murer, CH.; Baur, H.; Signer, P.; Wieler, R.

    1993-01-01

    Solar He, Ne, and Ar in a Fe-Ni separate from the chondrite Fayetteville are analyzed by closed system stepped oxidation. We report here data of the first 15 steps comprising 55 percent of the total solar gases. He-4/Ar-36 and Ne-20/Ar-36 are quite constant at values about 20 percent below those of present day solar wind (SWC). In this, Fe-Ni differs from lunar ilmenites where He-4/Ar-36 and Ne-20/Ar-36 in the first steps are several times below SWC. Thus, metal retains SW-noble gases even better than ilmenite, almost without element fractionation. Nevertheless, the isotopic composition of SW-He, -Ne, and -Ar in the first steps of the metal sample are identical to those found in a recently irradiated lunar ilmenite, indicating that ilmenites and chondritic metal both contain isotopically unfractionated SW noble gases. A preliminary analysis of a smaller Fayetteville metal separate shows Ne from solar energetic particles (SEP-Ne) with Ne-20/Ne-22 less than or equal to 11.5.

  19. Sequestration of noble gases by H3+ in protoplanetary disks and outer solar system composition

    E-print Network

    Olivier Mousis; Francoise Pauzat; Yves Ellinger; Cecilia Ceccarelli

    2007-09-23

    We study the efficiency of the noble gases sequestration by the ion H3+ in the form of XH3+ complexes (with X = argon, krypton or xenon) in gas phase conditions similar to those encountered during the cooling of protoplanetary disks, at the epoch of icy planetesimals formation. We show that XH3+ complexes form very stable structures in the gas phase and that their binding energies are much higher than those involved in the structures of X-H2O hydrates or pure X-X condensates. This implies that, in presence of H3+ ions, argon, krypton or xenon are likely to remain sequestrated in the form of XH3+ complexes embedded in the gas phase rather than forming ices during the cooling of protoplanetary disks. The amount of the deficiency depends on how much H3+ is available and efficient in capturing noble gases. In the dense gas of the mid-plane of solar nebula, H3+ is formed by the ionization of H2 from energetic particles, as those in cosmic rays or those ejected by the young Sun. Even using the largest estimate of the cosmic rays ionization rate, we compute that the H3+ abundance is two and three orders of magnitude lower than the xenon and krypton abundance, respectively. Estimating the ionization induced by the young Sun, on the other hand, is very uncertain but leaves the possibility to have enough H3+ to make krypton and xenon trapping efficent. Finally, additional source of H3+ formation may be provided by the presence of a nearby supernova, as discussed in the literature. Recent solar system observations show a deficiency of Ar, and, even more, of Kr and Xe in Titan and in comets. In this article, we consider the possibility that this deficiency is caused by the afore-mentioned process, namely trapping of those noble gases by H3+ ions in the solar nebula.

  20. Enhancement of NMR and MRI in the presence of hyperpolarized noble gases

    DOEpatents

    Pines, Alexander; Budinger, Thomas; Navon, Gil; Song, Yi-Qiao; Appelt, Stephan; Bifone, Angelo; Taylor, Rebecca; Goodson, Boyd; Seydoux, Roberto; Room, Toomas; Pietrass, Tanja

    2004-11-16

    The present invention relates generally to nuclear magnetic resonance (NMR) techniques for both spectroscopy and imaging. More particularly, the present invention relates to methods in which hyperpolarized noble gases (e.g., Xe and He) are used to enhance and improve NMR and MRI. Additionally, the hyperpolarized gas solutions of the invention are useful both in vitro and in vivo to study the dynamics or structure of a system. When used with biological systems, either in vivo or in vitro, it is within the scope of the invention to target the hyperpolarized gas and deliver it to specific regions within the system.

  1. Cross sections and transport properties of Cl- ions in noble gases

    NASA Astrophysics Data System (ADS)

    Petrovi?, Z. Lj.; Jovanovi?, J. V.; Stojanovi?, V.; Raspopovi?, Z. M.; Ristivojevi?, Z.

    2008-06-01

    We have used a simple semi-analytic — momentum transfer theory (MTT) to develop negative halogen ions/noble gases momentum transfer integral cross sections based on the available data for reduced mobility at 300 K as a function of E/N. The unfolded cross sections were validated or further improved by assuring a good agreement between our Monte Carlo (MC) calculated transport data and the available experimental results. The data are produced with an aim to provide plasma modellers with cross section data and transport coefficients. We have also calculated the net rates of elastic scattering and detachment.

  2. Crystal–melt partitioning of noble gases (helium, neon, argon, krypton, and xenon) for olivine and clinopyroxene

    Microsoft Academic Search

    Veronika S. Heber; Richard A. Brooker; Simon P. Kelley; Bernard J. Wood

    2007-01-01

    Mineral–melt partition coefficients of all noble gases (min\\/meltDi) have been obtained for olivine (ol) and clinopyroxene (cpx) by UV laser ablation (213nm) of individual crystals grown from melts at 0.1GPa mixed noble gas pressure. Experimental techniques were developed to grow crystals virtually free of melt and fluid inclusions since both have been found to cause profound problems in previous work.

  3. Experimental study of disruption mitigation using massive injection of noble gases on Tore Supra

    NASA Astrophysics Data System (ADS)

    Reux, C.; Bucalossi, J.; Saint-Laurent, F.; Gil, C.; Moreau, P.; Maget, P.

    2010-09-01

    Disruptions are a major threat for future tokamaks, including ITER. Disruption-generated heat loads, electromagnetic forces and runaway electrons will not be tolerable for next-generation devices. Massive noble gas injection is foreseen as a standard mitigation system for these tokamaks. Disruption mitigation experiments have been carried out on Tore Supra to study various injection scenarios and to investigate gas jet penetration and mixing. Comparisons of different gases (He, Ne, Ar, He/Ar mixture) and amounts (from 5 to 500 Pa m3) were made, showing that light gases are more efficient regarding runaway electron suppression than heavier gases. Eddy currents in the limiter are moderately reduced by all the gases, and may be more dependent on the time constants of the structures than on the gas species. The density rise induced by the massive injection before the thermal quench is higher and faster with light gases. Gas jet penetration in the cooling phase is observed to be shallow and independent of the gas nature and amount. The gas cold front is stopped along the q = 2 surface where it triggers MHD instabilities, expelling thermal energy from the plasma core.

  4. Gravity effects on a gliding arc in four noble gases: from normal to hypergravity

    NASA Astrophysics Data System (ADS)

    Poto??áková, L.; Šperka, J.; Zikán, P.; van Loon, J. J. W. A.; Beckers, J.; Kudrle, V.

    2015-04-01

    A gliding arc in four noble gases (He, Ne, Ar, Kr) has been studied under previously unexplored conditions of varying artificial gravity, from normal 1 g gravity up to 18 g hypergravity. Significant differences, mainly the visual thickness of the plasma channel, its maximum elongation and general sensitivity to hypergravity conditions, were observed between the discharges in individual gases, resulting from their different atomic weights and related quantities, such as heat conductivity or ionisation potential. Generally, an increase of the artificial gravity level leads to a faster plasma channel movement thanks to stronger buoyant force and a decrease of maximum height reached by the channel due to more intense losses of heat and reactive species. In relation to this, an increase in current and a decrease in absorbed power was observed.

  5. Noble gases in high-pressure silicate liquids: A computer simulation study

    NASA Astrophysics Data System (ADS)

    Guillot, Bertrand; Sator, Nicolas

    2012-03-01

    The test particle method has been used in conjunction with molecular dynamics simulations to evaluate the solubility of noble gases in silicate melts of various composition. At low pressure the calculated solubility constants (the inverse of the Henry's constant) are in excellent agreement with data of the literature. In particular it is found that the solubility constant (i) decreases when the size of the noble gas increases, (ii) decreases from silica-rich to silica-poor composition of the melt, and (iii) is positively correlated with the temperature. Moreover it is shown that the solubility is governed primarily by the entropic cost of cavity formation for inserting the noble gas into the melt and secondarily by its solvation energy. Interestingly, the behaviour of these two contributions differ from each other as the entropic cost of cavity formation increases strongly with the size of the solute atom to insert whereas large atoms are better solvated than small ones. Considerations of thermodynamics show that the weight fraction of a noble gas in a silicate melt coexisting with its parent fluid at T and P is equal to ng?m/nm?g, where ng and nm are the densities of the two coexisting phases (gas and melt, respectively) and where the solubility parameters ?m and ?g express the probability of inserting the noble gas atom in the melt and in the parent fluid, respectively. The ?m and ?g decrease drastically when the pressure is increased and the noble gas solubility at high pressure is the result of a balance between these two quantities. Here again, the pressure behaviour of ?m and ?g is dominated by the pressure dependence of the entropic cost of cavity formation, the energetic contribution being of minor importance but not negligible at high pressures. With all melt composition investigated here (silica, rhyolite, MORB and olivine), the calculated solubility curves exhibit the same qualitative behaviour with pressure; a steep rise culminating in a broad maximum followed by a gradual decrease of the solubility at higher pressure. At variance with LHDAC experiments (Chamorro-Pérez et al., 1996, 1998; Bouhifd et al., 2006, 2008) where a Ar solubility drop is observed at about 50 kbar in silica and molten olivine and in the pressure range ˜100-160 kbar with other melt composition, we do not find such a sudden change of the solubility.

  6. A new automated method for measuring noble gases and their isotopic ratios in water samples

    NASA Astrophysics Data System (ADS)

    Stanley, Rachel H. R.; Baschek, Burkard; Lott, Dempsey E.; Jenkins, William J.

    2009-05-01

    A method is presented for precisely measuring all five noble gases and their isotopic ratios in water samples using multiple programmed multistage cryogenic traps in conjunction with quadrupole mass spectrometry and magnetic sector mass spectrometry. Multiple automated cryogenic traps, including a two-stage cryotrap used for removal of water vapor, an activated charcoal cryotrap used for helium separation, and a stainless steel cryotrap used for neon, argon, krypton, and xenon separation, allow reproducible gas purification and separation. The precision of this method for gas standards is ±0.10% for He, ±0.14% for Ne, ±0.10% for Ar, ±0.14% for Kr, and ±0.17% for Xe. The precision of the isotopic ratios of the noble gases in gas standards are ±1.9‰ for 20Ne/22Ne, ±2.0‰ for 84Kr/86Kr, ±2.5‰ for 84Kr/82Kr, ±0.9‰ for 132Xe/129Xe, and ±1.3‰ for 132Xe/136Xe. The precision of this method for water samples, determined by measurement of duplicate pairs, is ±1% for He, ±0.9% for Ne, ±0.3% for Ar, ±0.3% for Kr, and ±0.2% for Xe. An attached magnetic sector mass spectrometer measures 3He/4He with precisions of ±0.1% for air standards and ±0.14% for water samples.

  7. Sequestration of noble gases by H3+ in protoplanetary disks and outer solar system composition

    E-print Network

    Mousis, Olivier; Ellinger, Yves; Ceccarelli, Cecilia

    2007-01-01

    We study the efficiency of the noble gases sequestration by the ion H3+ in the form of XH3+ complexes (with X = argon, krypton or xenon) in gas phase conditions similar to those encountered during the cooling of protoplanetary disks, at the epoch of icy planetesimals formation. We show that XH3+ complexes form very stable structures in the gas phase and that their binding energies are much higher than those involved in the structures of X-H2O hydrates or pure X-X condensates. This implies that, in presence of H3+ ions, argon, krypton or xenon are likely to remain sequestrated in the form of XH3+ complexes embedded in the gas phase rather than forming ices during the cooling of protoplanetary disks. The amount of the deficiency depends on how much H3+ is available and efficient in capturing noble gases. In the dense gas of the mid-plane of solar nebula, H3+ is formed by the ionization of H2 from energetic particles, as those in cosmic rays or those ejected by the young Sun. Even using the largest estimate of t...

  8. A theoretical investigation into the trapping of noble gases by clathrates on Titan

    E-print Network

    Caroline Thomas; Sylvain Picaud; Olivier Mousis; Vincent Ballenegger

    2008-03-19

    In this paper, we use a statistical thermodynamic approach to quantify the efficiency with which clathrates on the surface of Titan trap noble gases. We consider different values of the Ar, Kr, Xe, CH4, C2H6 and N2 abundances in the gas phase that may be representative of Titan's early atmosphere. We discuss the effect of the various parameters that are chosen to represent the interactions between the guest species and the ice cage in our calculations. We also discuss the results of varying the size of the clathrate cages. We show that the trapping efficiency of clathrates is high enough to significantly decrease the atmospheric concentrations of Xe and, to a lesser extent, of Kr, irrespective of the initial gas phase composition, provided that these clathrates are abundant enough on the surface of Titan. In contrast, we find that Ar is poorly trapped in clathrates and, as a consequence, that the atmospheric abundance of argon should remain almost constant. We conclude that the mechanism of trapping noble gases via clathration can explain the deficiency in primordial Xe and Kr observed in Titan's atmosphere by Huygens, but that this mechanism is not sufficient to explain the deficiency in Ar.

  9. Signal Dynamics in Magnetic Resonance Imaging of the Lung with Hyperpolarized Noble Gases*1

    NASA Astrophysics Data System (ADS)

    Möller, Harald E.; Chen, X. Josette; Chawla, Mark S.; Driehuys, Bastiaan; Hedlund, Laurence W.; Johnson, G. Allan

    1998-11-01

    The nonequilibrium bulk magnetic moment of hyperpolarized (HP) noble gases generated by optical pumping has unique characteristics. Based on the Bloch equations, a model was developed describing the signal dynamics of HP gases used in magnetic resonance imaging (MRI) of the lung with special consideration to the breathing cycle. Experimental verification included extensive investigations with HP 3He and 129Xe during both inspiration and held breath in live guinea pigs. Radial acquisition was used to investigate the view variations with a temporal resolution of 5 ms. Agreement between theoretical predictions and in vivoresults was excellent. Additionally, information about effects from noble gas diffusion and spin-lattice relaxation was obtained. In vivoresults for T 1were 28.8 ± 1.8 s for 3He and 31.3 ± 1.8 s for 129Xe. Comparison with in vitrodata indicated that relaxation in the pulmonary gas space is dominated by dipolar coupling with molecular oxygen. The results provide a quantitative basis for optimizing pulse sequence design in HP gas MRI of the lung.

  10. Laboratory simulation of meteoritic noble gases. III - Sorption of neon, argon, krypton, and xenon on carbon - Elemental fractionation

    NASA Technical Reports Server (NTRS)

    Wacker, John F.

    1989-01-01

    The sorption of Ne, Ar, Kr, and Xe was studied in carbon black, acridine carbon, and diamond in an attempt to understand the origin of trapped noble gases in meteorites. The results support a model in which gases are physically adsorbed on interior surfaces formed by a pore labyrinth within amorphous carbons. The data show that: (1) the adsorption/desorption times are controlled by choke points that restrict the movement of noble gas atoms within the pore labyrinth, and (2) the physical adsorption controls the temperature behavior and elemental fractionation patterns.

  11. Modelling of noble anaesthetic gases and high hydrostatic pressure effects in lipid bilayers

    DOE PAGESBeta

    Moskovitz, Yevgeny [Middle Tennessee State University; Yang, Hui [Middle Tennessee State University

    2015-01-01

    Our objective was to study molecular processes that might be responsible for inert gas narcosis and high-pressure nervous syndrome. The classical molecular dynamics trajectories (200 ns-long) of dioleoylphosphatidylcholine (DOPC) bilayers simulated by the Berger force field were evaluated for water and the atomic distribution of noble gases around DOPC molecules at a pressure range of 1 - 1000 bar and temperature of 310 Kelvin. Xenon and argon have been tested as model gases for general anesthetics, and neon has been investigated for distortions that are potentially responsible for neurological tremor at hyperbaric conditions. The analysis of stacked radial pair distribution functions of DOPC headgroup atoms revealed the explicit solvation potential of gas molecules, which correlates with their dimensions. The orientational dynamics of water molecules at the biomolecular interface should be considered as an influential factor; while excessive solvation effects appearing in the lumen of membrane-embedded ion channels could be a possible cause of inert gas narcosis. All the noble gases tested exhibit similar patterns of the order parameter for both DOPC acyl chains, which is opposite to the patterns found for the order parameter curve at high hydrostatic pressures in intact bilayers. This finding supports the ‘critical volume’ hypothesis of anesthesia pressure reversal. The irregular lipid headgroup-water boundary observed in DOPC bilayers saturated with neon in the pressure range of 1 - 100 bar could be associated with the possible manifestation of neurological tremor at the atomic scale. The non-immobilizer neon also demonstrated the highest momentum impact on the normal component of the DOPC diffusion coefficient representing monolayers undulations rate, which indicates enhanced diffusivity, rather than atom size, as the key factor.

  12. Modelling of noble anaesthetic gases and high hydrostatic pressure effects in lipid bilayers.

    PubMed

    Moskovitz, Yevgeny; Yang, Hui

    2015-03-01

    Our objective was to study molecular processes that might be responsible for inert gas narcosis and high-pressure nervous syndrome. The classical molecular dynamics trajectories (200 ns) of dioleoylphosphatidylcholine (DOPC) bilayers simulated by the Berger force field were evaluated for water and the atomic distribution of noble gases around DOPC molecules in the pressure range of 1-1000 bar and at a temperature of 310 K. Xenon and argon have been tested as model gases for general anaesthetics, and neon has been investigated for distortions that are potentially responsible for neurological tremors in hyperbaric conditions. The analysis of stacked radial pair distribution functions of DOPC headgroup atoms revealed the explicit solvation potential of the gas molecules, which correlates with their dimensions. The orientational dynamics of water molecules at the biomolecular interface should be considered as an influential factor, while excessive solvation effects appearing in the lumen of membrane-embedded ion channels could be a possible cause of inert gas narcosis. All the noble gases tested exhibit similar order parameter patterns for both DOPC acyl chains, which are opposite of the patterns found for the order parameter curve at high hydrostatic pressures in intact bilayers. This finding supports the 'critical volume' hypothesis of anaesthesia pressure reversal. The irregular lipid headgroup-water boundary observed in DOPC bilayers saturated with neon in the pressure range of 1-100 bar could be associated with the possible manifestation of neurological tremors at the atomic scale. The non-immobiliser neon also demonstrated the highest momentum impact on the normal component of the DOPC diffusion coefficient representing the monolayer undulation rate, which indicates that enhanced diffusivity rather than atomic size is the key factor. PMID:25612767

  13. Crustal noble gases in deep brines as natural tracers of vertical transport processes in the Michigan Basin

    NASA Astrophysics Data System (ADS)

    Ma, Lin; Castro, Maria Clara; Hall, Chris M.

    2009-06-01

    Noble gas concentrations and isotopic ratios are presented for 38 deep (˜0.5-3.6 km) brine samples in the Michigan Basin. These brine samples clearly show the presence of an important crustal component of 4He, 21Ne, 40Ar, and 136Xe. Both 40Arcrust and 136Xecrust display the presence of a strong vertical gradient along the sedimentary strata of the basin. We show that the in situ production for these two gases within the sedimentary strata is insufficient to account for the observed crustal component in the Michigan brines. These point to the presence of a deep, external source for crustal noble gases, likely the Precambrian crystalline basement beneath the Michigan Basin. Furthermore, observed elemental ratios of crustal noble gases (4He/40Ar, 21Ne/40Ar, 4He/136Xe, and 21Ne/136Xe) in these brines vary over several orders of magnitude with respect to the expected production ratios from the crystalline basement rocks and display a systematic pattern within the basin. Specifically, samples above the Salina Group (shallow formations) are relatively enriched in 4Hecrust and 21Necrust with respect to 40Arcrust and 136Xecrust, as opposed to those below the massive Salina evaporite layer (deeper formations) which exhibit complementary patterns. We show that such a general trend is best explained by a Rayleigh-type elemental fractionation model involving upward transport of crustal noble gases and associated elemental fractionation processes, controlled by both diffusion- and solubility-related mechanisms. As previously indicated by the mantle and atmospheric noble gas signatures in these same Michigan brine samples, release of deep crustal noble gases into the basin is yet another independent indicator pointing to the occurrence of a past thermal event in the basin. We suggest that recent reactivation of the ancient midcontinent rift system underneath the Michigan Basin is likely responsible for the upward transport of heat and loss of the atmospheric noble gas component, as well as release of crustal (still ongoing) and mantle noble gases into the basin via deep-seated faults and fracture zones. Such a model also supports an internal heat source hypothesis as being largely responsible for the existence of past high temperatures in the basin without involvement of large-scale brine migration from peripheral forming orogenic fold belts.

  14. A Complex Exposure History of the Gold Basin L4-Chondrite Shower from Cosmogenic Radionuclides and Noble Gases

    NASA Technical Reports Server (NTRS)

    Welten, K. C.; Nishiizumi, K.; Caffee, M. W.; Masarik, J.; Wieler, R.

    2001-01-01

    Cosmogenic radionuclides and noble gases in samples of the Gold Basin L-chondrite shower indicate a complex exposure history, with a first stage exposure on the parent body, followed by a second stage of approx. 19 Myr in a meteoroid 3-4 m in radius. Additional information is contained in the original extended abstract.

  15. Impact of artificial recharge on dissolved noble gases in groundwater in California.

    PubMed

    Cey, Bradley D; Hudson, G Bryant; Moran, Jean E; Scanlon, Bridget R

    2008-02-15

    Dissolved noble gas concentrations in groundwater can provide valuable information on recharge temperatures and enable 3H-3He age-dating with the use of physically based interpretive models. This study presents a large (905 samples) data set of dissolved noble gas concentrations from drinking water supply wells throughout California, representing a range of physiographic, climatic, and water management conditions. Three common interpretive models (unfractionated air, UA; partial re-equilibration, PR; and closed system equilibrium, CE) produce systematically different recharge temperatures or ages; however, the ability of the different models to fit measured data within measurement uncertainty indicates that goodness-of-fit is not a robust indicator for model appropriateness. Therefore caution is necessary when interpreting model results. Samples from multiple locations contained significantly higher Ne and excess air concentrations than reported in the literature, with maximum excess air tending toward 0.05 cm3 STP g(-1) (deltaNe approximately 400%). Artificial recharge is the most plausible cause of the high excess air concentrations. The ability of artificial recharge to dissolve greater amounts of atmospheric gases has important implications for oxidation-reduction dependent chemical reactions. Measured gas concentration ratios suggest that diffusive degassing may have occurred. Understanding the physical processes controlling gas dissolution during groundwater recharge is critical for optimal management of artificial recharge and for predicting changes in water quality that can occur following artificial recharge. PMID:18351066

  16. Momentum transfer cross sections for the heavy noble gases

    NASA Astrophysics Data System (ADS)

    Stauffer, A. D.; McEachran, R. P.

    2012-10-01

    We have used our relativistic optical potential method [1] to calculate the momentum transfer cross sections for Ar, Kr and Xe from threshold to 1000 eV. The target ground state as well as the open excited and ionization channels used in the optical potential have been calculated using the MCDF program [2]. We have included 17 excitation channels for Ar, 26 for Kr and 15 for Xe. In the ionization channels, ionization of the outer p, s and d shells were included for Kr and Xe while for Ar all electrons were allowed to be ionized. Comparisons with previous calculations and experimental measurements will be included. We also include analytic fits to our cross sections to aid in plasma modelling studies. [4pt] [1] S. Chen, R. P. McEachran and A. D. Stauffer, J. Phys. B 41 025201 (2008) [0pt] [2] I. P. Grant, B. J. McKenzie, P. H. Norrington, D. F. Mayers and N. C. Pyper, Comput. Phys. Commun. 21 207 (1980)

  17. Observation of Threshold Effects in Positron Scattering from the Noble Gases

    NASA Astrophysics Data System (ADS)

    Jones, A. C. L.; Caradonna, P.; Makochekanwa, C.; Slaughter, D. S.; McEachran, R. P.; Machacek, J. R.; Sullivan, J. P.; Buckman, S. J.

    2010-08-01

    Channel coupling is a phenomenon that has been investigated for many scattering processes, and is responsible for the formation of cusps or steps in the cross sections for open scattering channels at, or near, the onset of a new scattering channel. It has long been speculated that the opening of the positronium formation channel may lead to the formation of such cusp features in the elastic positron scattering cross section. In this work, elastic scattering of positrons has been measured in the region of the positronium formation threshold for the noble gases He-Xe. Cusplike behavior is observed and, while the features which are observed appear broad, they represent a magnitude of between 4 and 15% of the total elastic cross section. No evidence is found of any other features in this region, at least within the uncertainty of the present data, discounting the possibility of scattering resonances.

  18. On segregation of noble gases in water-based Single Bubble Sonoluminescence

    NASA Astrophysics Data System (ADS)

    Levinsen, Mogens

    2011-03-01

    A long-standing issue in the field of long time stable water based single bubble sonoluminescence has been the close similarity of the spectra to that of blackbody radiation. Looking for the effects of possible segregation of noble gases has been suggested as a means to investigate whether the similarity is just a weird coincidence with the bubbles being on the whole transparent to their own radiation. We have investigated spectra from bubbles seeded with various mixtures of helium and neon with xenon and argon using a novel transformation that allows for a single parameter characterization of the spectra, with the surprising result that although no trace of segregation is found, the radiation seems to be highly thermalized in all cases.

  19. Laboratory simulation of meteoritic noble gases. I - Sorption of xenon on carbon: Trapping experiments

    NASA Technical Reports Server (NTRS)

    Wacker, J. F.; Zadnik, M. G.; Anders, E.

    1985-01-01

    The sorption of Xe-127 at 5 x 10 to the -7th atm onto carbon black, pyrolyzed polyvinylidene chloride, and pyrolyzed acridine at 100-1000 C for 5 min-240 h is measured experimentally by gamma spectrometry. The results are presented in tables and graphs and characterized in detail. The tightly bound Xe remaining in the samples after 4000 min pumping at temperatures above 100 C is found to comprise two components: a low-temperature component attributed to physisorption within an atomic-scale labyrinth of micropores, and a high-temperature component due to volume diffusion. The implications for the trapping of noble gases near grain surfaces of amorphous carbon in meteorites are considered.

  20. Atmospheric noble gases as tracers of biogenic gas dynamics in a shallow unconfined aquifer

    NASA Astrophysics Data System (ADS)

    Jones, Katherine L.; Lindsay, Matthew B. J.; Kipfer, Rolf; Mayer, K. Ulrich

    2014-03-01

    Atmospheric noble gases (NGs) were used to investigate biogenic gas dynamics in a shallow unconfined aquifer impacted by a crude oil spill, near Bemidji, MN. Concentrations of 3,4He, 20,22Ne, 36,40Ar, Kr, and Xe were determined for gas- and aqueous-phase samples collected from the vadose and saturated zones, respectively. Systematic elemental fractionation of Ne, Ar, Kr, and Xe with respect to air was observed in both of these hydrogeologic zones. Within the vadose zone, relative ratios of Ne and Ar to Kr and Xe revealed distinct process-related trends when compared to corresponding ratios for air. The degree of NG deviation from atmospheric concentrations generally increased with greater atomic mass (i.e., ?Xe > ?Kr > ?Ar > ?Ne), indicating that Kr and Xe are the most sensitive NG tracers in the vadose zone. Reactive transport modeling of the gas data confirms that elemental fractionation can be explained by mass-dependent variations in diffusive fluxes of NGs opposite to a total pressure gradient established between different biogeochemical process zones. Depletion of atmospheric NGs was also observed within a methanogenic zone of petroleum hydrocarbon degradation located below the water table. Solubility normalized NG abundances followed the order Xe > Kr > Ar > Ne, which is indicative of dissolved NG partitioning into the gas phase in response to bubble formation and possibly ebullition. Observed elemental NG ratios of Ne/Kr, Ne/Xe, Ar/Xe, and Kr/Xe and a modeling analysis provide strong evidence that CH4 generation below the water table caused gas exsolution and possibly ebullition and carbon transfer from groundwater to the vadose zone. These results suggest that noble gases provide sensitive tracers in biologically active unconfined aquifers and can assist in identifying carbon cycling and transfer within the vadose zone, the capillary fringe, and below the water table.

  1. Simultaneous analysis of noble gases, sulfur hexafluoride, and other dissolved gases in water.

    PubMed

    Brennwald, Matthias S; Hofer, Markus; Kipfer, Rolf

    2013-08-01

    We developed an analytical method for the simultaneous measurement of dissolved He, Ne, Ar, Kr, Xe, SF6, N2, and O2 concentrations in a single water sample. The gases are extracted from the water using a head space technique and are transferred into a vacuum system for purification and separation into different fractions using a series of cold traps. Helium is analyzed using a quadrupole mass spectrometer (QMS). The remaining gas species are analyzed using a gas chromatograph equipped with a mass spectrometer (GC-MS) for analysis of Ne, Ar, Kr, Xe, N2, and O2 and an electron capture detector (GC-ECD) for SF6 analysis. Standard errors of the gas concentrations are approximately 8% for He and 2-5% for the remaining gas species. The method can be extended to also measure concentrations of chlorofluorocarbons (CFCs). Tests of the method in Lake Lucerne (Switzerland) showed that dissolved gas concentrations agree with measurements from other methods and concentrations of air saturated water. In a small artificial pond, we observed systematic gas supersaturations, which seem to be linked to adsorption of solar irradiation in the pond and to water circulation through a gravel bed. PMID:23826704

  2. Are the C delta light nitrogen and noble gases located in the same carrier?

    NASA Technical Reports Server (NTRS)

    Verchovsky, A. B.; Russell, S. S.; Pillinger, C. T.; Fisenko, A. V.; Shukolyukov, Yuri A.

    1993-01-01

    Light nitrogen and the HL family noble gas components of C(sub delta) appear to be separable by high resolution pyrolysis experiments. Thus C(sub delta) is not a homogeneous material and probably consists of debris of many stars. The question of whether the N and Xe(HL) actually reside in different carriers continues to be addressed. It is well known that C(sub delta) which was identified as nanometer sized diamonds contains isotopically anamalous elements, in particular noble gases including Xe(HL) and its family and light nitrogen (delta(N-15) down to -350 percent). Before the true nature of C(sub delta) was recognized, it was easy to suppose that the Xe(HL) and light nitrogen were located in the same carrier. However, recognition that light nitrogen in diamond from different samples varies by greater than a factor of six compared to Xe(HL) fluctuations of ca. 20 percent makes such an assumption questionable. On the basis of simple arithmetic logic, the Xe and nitrogen cannot be absolutely co-located. The average diamond grain consists of only about 1000-2000 atoms of carbon; one grain among a few x 10(exp 6) contains an atom of Xe(HL) while 5-30 atoms of light nitrogen are the typical number which need to be in every diamond grain to account for observed concentrations. If some grains are devoid of N, the others have to have a higher N concentration. Even if we were able to analyze an individual grain of the diamond for noble gases and nitrogen, we would be faced with the monumental task of locating the one amongst 10(exp 6) identical grains containing the Xe atom to examine its nitrogen content. The problem can be simplified to some extent if instead of Xe, He which is 10(exp 4) times more abundant is assumed to be a member of the HL family. Attempts to fractionate the separate carriers might be attempted using He and N as guiding indicators but even experiments of this nature are for the future. Faced with apparently insoluble problems, we have returned to an investigation we last used in our original efforts to find isotopically light nitrogen, that is to compare release patterns of the different components during stepped pyrolysis and combustion.

  3. Dissolved Noble Gases in Rainwater, Southern Michigan - Evidence for Lack of Rainwater Equilibration with the Atmosphere at Surface Conditions

    NASA Astrophysics Data System (ADS)

    Warrier, R. B.; Castro, M.; Hall, C. M.

    2012-12-01

    Atmospheric noble gases dissolved in groundwater have been extensively used to reconstruct the past climate. A key assumption of the noble gas thermometer is that rainwater is in equilibrium with ground air when it reaches the water table. However, our recent study conducted in the Galapagos Islands showed that dissolved atmospheric noble gas concentrations in high-altitude spring samples display high apparent recharge altitudes, cold apparent temperatures and a unique, previously unknown noble gas pattern. In addition to atmospheric He excesses, this pattern displays Ne, Kr, and Xe depletion together with relative Ar enrichment. We hypothesized that this unexpected noble gas pattern resulted from the combined effect of a lack of rainwater equilibration at high altitudes in the atmosphere and the impact of fog droplets on noble gas concentrations in groundwater. To understand the origin of this previously unknown noble gas pattern, we analyzed He, Ne, Ar, Kr and Xe dissolved in 12 rainwater samples resulting from the passage of both warm and cold fronts in southern Michigan. Preliminary results show that all samples present atmospheric He excesses, ranging between 1% and 29% with respect to air saturated water (ASW) for corresponding measured temperature and altitude values at the time and location of sampling. In addition, these samples can be subdivided into two groups with distinct patterns. The first group displays a pattern remarkably similar to the unique anomalous pattern observed in high-altitude spring samples in the Galapagos Islands with relative Ar enrichment and Ne, Kr, and Xe depletion. The second group displays a mass-dependent pattern with greater depletion of the heavier noble gases Kr and Xe as compared to the lighter noble gases Ne and Ar. The first group of rainwater samples was mostly collected during the passage of warm fronts, which are typically associated with light, steady precipitation and gradual adiabatic uplift of air masses as compared to cold fronts. Light, steady precipitation in the presence of stable inversion clouds is also observed at high altitudes in the Galapagos Islands and suggests that similar precipitation conditions in these distinct locations is at least partly responsible for the unique anomalous noble gas patterns in these samples. In contrast, the second group of rain samples was mostly collected during thunderstorms. In particular, mass-dependent noble gas patterns displayed by these samples closely match the severe depletion of Ar, Kr, and Xe together with He enrichment observed in ice. It is possible that many of the features seen in these rain samples can be explained if rain begins as ice within rain clouds. Indeed, mixing of condensed liquid water with melted ice in the form of pellets or snow might provide a partial explanation for the observed mass-dependent noble gas patterns in rainwater samples. Our preliminary results suggest that dissolved noble gases in rainwater are not in equilibrium with surface conditions and warrants further field and laboratory experiments.

  4. Noble gases in the sediments of Lake Van - solute transport and palaeoenvironmental reconstruction

    NASA Astrophysics Data System (ADS)

    Tomonaga, Yama; Brennwald, Matthias S.; Meydan, Ay?egül F.; Kipfer, Rolf

    2014-11-01

    Sediment samples acquired in 2010 from the long cores of the International Continental Scientific Drilling Program (ICDP) PaleoVan drilling project on Lake Van for noble-gas analysis in the pore water allow determination of the local terrestrial He-gradient as a function of depth within a sediment column of more than 200 m. These measurements yield first insights into the physical transport mechanisms of terrigenic He through the uppermost part of unconsolidated lacustrine sediments overlying the continental crust. In line with our previous work on the spatial distribution of the terrigenic He release into Lake Van, we identify a high He concentration gradient in the uppermost 10 m of the sediment column. The He concentration gradient decreases below this depth down to approx. 160 m following in general the expectations of the modelling of radiogenic He production and transport in a sediment column with homogeneous fluid transport properties. Overall the in-situ radiogenic He production due to the decay of U and Th in the mineral phases of the sediments accounts for about 80% of the He accumulation. At approx. 190 m we observe a very high He concentration immediately below a large lithological unit characterised by strong deformations. We speculate that this local enrichment is the result of the lower effective diffusivities in the pore space that relate to the abrupt depositional history of this deformed unit. This particular lithological unit seems to act as a barrier that limits the transport of solutes in the pore space and hence might "trap" information on the past geochemical conditions in the pore water of Lake Van. The dissolved concentrations of atmospheric noble gases in the pore waters of the ICDP PaleoVan cores are used to geochemically reconstruct salinity on the time scale of 0-55 ka BP. Higher salinities in the pore water at a depth of about 20 m suggest a significantly lower lake level of Lake Van in the past.

  5. Using noble gases in the pore water of ocean sediments to characterize CH4 seepage off the coast of New Zealand

    NASA Astrophysics Data System (ADS)

    Tomonaga, Yama; Brennwald, Matthias S.; Kipfer, Rolf

    2013-04-01

    Newly developed analytical techniques to determine the abundances of noble gases in sediment pore water [1, 5] allow noble-gas concentrations and isotope ratios to be measured easily and routinely in unconsolidated lacustrine sediments [6, 7]. We applied these techniques for the first time to ocean sediments to investigate an active cold methane seepage system located in the South Pacific off the coast of New Zealand using 3He-4He ratios determined in the sediment pore water. Our results [8] show that more 3He-rich fluids are released in the vicinity of the Pacific-Australian subduction zone than at the forearc stations located closer to the New Zealand coast. However, the 3He-4He isotope signature in the sediment column indicates that only a minor part of the He emanating from deeper strata originates from a (depleted) mantle source. Hence, most He in the pore water is produced locally by the radioactive decay of U and Th in the sediment minerals or in the underlying crustal rocks. Such an occurrence of isotopically heavy crustal He also suggests that the source of the largest fraction of methane is a near-surface geochemical reservoir. This finding is in line with a previous ?13C study in the water column which concluded that the emanating methane is most likely of biological origin and is formed in the upper few meters of the sediment column [2]. The prevalence of isotopically heavy He agrees well with the outcome of other previous studies on island arc systems [3, 4] which indicate that the forearc regions are characterized by crustal He emission, whereas the volcanic arc region is characterized by the presence of mantle He associated with rising magma. References [1] Brennwald, M. S., Hofer, M., Peeters, F., Aeschbach-Hertig, W., Strassmann, K., Kipfer, R., and Imboden, D. M. (2003). Analysis of dissolved noble gases in the pore water of lacustrine sediments. Limnol. Oceanogr.: Methods 1, 51-62. [2] Faure, K., Greinert, J., Schneider von Deimling, J., McGinnis, D., Kipfer, R., Linke, P. (2010). Methane seepage along the Hikurangi Margin of New Zealand: Geochemical and physical data from the water column, sea surface and atmosphere. Mar. Geol. 272, 170-188. [3] Sano, Y., Nakajima, J. (2008). Geographical distribution of 3He-4He ratios and seismic tomography in Japan. Geochem. J. 42, 51-60. [4] Sano, Y., Wakita, H., Giggenbach, W., 1987. Island arc tectonics of New Zealand manifested in helium isotope ratios. Geochim. Cosmochim. Acta 51 (7), 1855-1860. [5] Tomonaga, Y., Brennwald, M. S., Kipfer, R. (2011). An improved method for the analysis of dissolved noble gases in the pore water of unconsolidated sediments. Limnol. Oceanogr.: Methods 9, 42-49. [6] Tomonaga, Y., Brennwald, M. S., Kipfer, R. (2011). Spatial distribution and flux of terrigenic He dissolved in the sediment pore water of Lake Van (Turkey). Geochim. Cosmochim. Acta 75 (10), 2848-2864. [7] Tomonaga, Y., Blättler, R., Brennwald, M. S., Kipfer, R. (2012). Interpreting noble-gas concentrations as proxies for salinity and temperature in the world's largest soda lake (Lake Van, Turkey). J. Asian Earth Sci., 59, 99-107. [8] Tomonaga, Y., Brennwald, M. S., Kipfer, R. Using noble gases in ocean sediments to characterize active methane seepage off the coast of New Zealand. Mar. Geol., submitted.

  6. ULTRAHIGH SENSITIVITY HEAVY NOBLE GAS DETECTORS FOR LONG-TERM MONITORING AND MONITORING AIR

    EPA Science Inventory

    A Georgia Institute of Technology/Argonne National Laboratory team will develop and demonstrate novel ultrahigh sensitivity heavy noble gas (krypton, xenon, and radon) detectors for long-term monitoring of spent fuel and TRU waste, as well as for distinguishing background radon a...

  7. Relativistic contributions to single and double core electron ionization energies of noble gases

    NASA Astrophysics Data System (ADS)

    Niskanen, J.; Norman, P.; Aksela, H.; Ågren, H.

    2011-08-01

    We have performed relativistic calculations of single and double core 1s hole states of the noble gas atoms in order to explore the relativistic corrections and their additivity to the ionization potentials. Our study unravels the interplay of progression of relaxation, dominating in the single and double ionization potentials of the light elements, versus relativistic one-electron effects and quantum electrodynamic effects, which dominate toward the heavy end. The degree of direct relative additivity of the relativistic corrections for the single electron ionization potentials to the double electron ionization potentials is found to gradually improve toward the heavy elements. The Dirac-Coulomb Hamiltonian is found to predict a scaling ratio of ˜4 for the relaxation induced relativistic energies between double and single ionization. Z-scaling of the computed quantities were obtained by fitting to power law. The effects of nuclear size and form were also investigated and found to be small. The results indicate that accurate predictions of double core hole ionization potentials can now be made for elements across the full periodic table.

  8. Relativistic contributions to single and double core electron ionization energies of noble gases

    SciTech Connect

    Niskanen, J. [Department of Physics, University of Oulu, Box 3000, 90014 Oulu (Finland); Department of Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm (Sweden); Norman, P. [Linkoeping University, SE-581 83 Linkoeping (Sweden); Aksela, H. [Department of Physics, University of Oulu, Box 3000, 90014 Oulu (Finland); Aagren, H. [Department of Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm (Sweden)

    2011-08-07

    We have performed relativistic calculations of single and double core 1s hole states of the noble gas atoms in order to explore the relativistic corrections and their additivity to the ionization potentials. Our study unravels the interplay of progression of relaxation, dominating in the single and double ionization potentials of the light elements, versus relativistic one-electron effects and quantum electrodynamic effects, which dominate toward the heavy end. The degree of direct relative additivity of the relativistic corrections for the single electron ionization potentials to the double electron ionization potentials is found to gradually improve toward the heavy elements. The Dirac-Coulomb Hamiltonian is found to predict a scaling ratio of {approx}4 for the relaxation induced relativistic energies between double and single ionization. Z-scaling of the computed quantities were obtained by fitting to power law. The effects of nuclear size and form were also investigated and found to be small. The results indicate that accurate predictions of double core hole ionization potentials can now be made for elements across the full periodic table.

  9. Measuring radioactive noble gases by absorption in polycarbonates and other organics: From radon indoors to nuclear safety

    NASA Astrophysics Data System (ADS)

    Pressyanov, Dobromir S.

    2013-07-01

    The report summarizes recent research and practice of using materials with high absorption ability to noble gases to measure their radioactive isotopes. Most of the studies employ bisphenol-A based polycarbonates, because of their remarkably high absorption ability to noble gases. This is the material of which commercial CDs/DVDs are made and they may serve as serendipitous, already available in dwellings, radon and thoron detectors. We present the essence of the gathered experimental evidence that the CD/DVD method can successfully address some long-lasted problems in radon dosimetry: The first is making sufficiently precise retrospective 222Rn dosimetry for the purposes of epidemiological studies and risk estimation. The second is rapid identification of buildings with radon problem. We demonstrate how this can be used to develop an integrated approach to the radon problem. Within this approach detection, diagnostic and mitigation are considered as an unified whole, and the interval between the decision to provide disks for analysis and the complete mitigation of the building, if radon problem is identified, is short. Besides radon and thoron, bisphenol-A based polycarbonates were successfully used to measure 85Kr and 133Xe for the purposes of the effluents control and nuclear safety of nuclear installations. The perspectives to employ other organic materials in which noble gases are highly soluble for measurement of their radioactive isotopes are also discussed.

  10. The determination of accurate dipole polarizabilities alpha and gamma for the noble gases

    NASA Technical Reports Server (NTRS)

    Rice, Julia E.; Taylor, Peter R.; Lee, Timothy J.; Almloef, Jan

    1989-01-01

    The static dipole polarizabilities alpha and gamma for the noble gases helium through xenon were determined using large flexible one-particle basis sets in conjunction with high-level treatments of electron correlation. The electron correlation methods include single and double excitation coupled-cluster theory (CCSD), an extension of CCSD that includes a perturbational estimate of connected triple excitations, CCSD(T), and second order perturbation theory (MP2). The computed alpha and gamma values are estimated to be accurate to within a few percent. Agreement with experimental data for the static hyperpolarizability gamma is good for neon and xenon, but for argon and krypton the differences are larger than the combined theoretical and experimental uncertainties. Based on our calculations, we suggest that the experimental value of gamma for argon is too low; adjusting this value would bring the experimental value of gamma for krypton into better agreement with our computed result. The MP2 values for the polarizabilities of neon, argon, krypton and zenon are in reasonabe agreement with the CCSD and CCSD(T) values, suggesting that this less expensive method may be useful in studies of polarizabilities for larger systems.

  11. Analytical equation of state with three-body forces: Application to noble gases

    SciTech Connect

    Río, Fernando del, E-mail: fdr@xanum.uam.mx; Díaz-Herrera, Enrique; Guzmán, Orlando; Moreno-Razo, José Antonio [Departamento de Física, Universidad Autónoma Metropolitana, Iztapalapa, Apdo 55 534, México DF, 09340 (Mexico)] [Departamento de Física, Universidad Autónoma Metropolitana, Iztapalapa, Apdo 55 534, México DF, 09340 (Mexico); Ramos, J. Eloy [Colegio de Ciencia y Tecnología, Universidad Autónoma de la Ciudad de México, Mexico DF (Mexico)] [Colegio de Ciencia y Tecnología, Universidad Autónoma de la Ciudad de México, Mexico DF (Mexico)

    2013-11-14

    We developed an explicit equation of state (EOS) for small non polar molecules by means of an effective two-body potential. The average effect of three-body forces was incorporated as a perturbation, which results in rescaled values for the parameters of the two-body potential. These values replace the original ones in the EOS corresponding to the two-body interaction. We applied this procedure to the heavier noble gases and used a modified Kihara function with an effective Axilrod-Teller-Muto (ATM) term to represent the two- and three-body forces. We also performed molecular dynamics simulations with two- and three-body forces. There was good agreement between predicted, simulated, and experimental thermodynamic properties of neon, argon, krypton, and xenon, up to twice the critical density and up to five times the critical temperature. In order to achieve 1% accuracy of the pressure at liquid densities, the EOS must incorporate the effect of ATM forces. The ATM factor in the rescaled two-body energy is most important at temperatures around and lower than the critical one. Nonetheless, the rescaling of two-body diameter cannot be neglected at liquid-like densities even at high temperature. This methodology can be extended straightforwardly to deal with other two- and three-body potentials. It could also be used for other nonpolar substances where a spherical two-body potential is still a reasonable coarse-grain approximation.

  12. Analytical equation of state with three-body forces: application to noble gases.

    PubMed

    del Río, Fernando; Díaz-Herrera, Enrique; Guzmán, Orlando; Moreno-Razo, José Antonio; Ramos, J Eloy

    2013-11-14

    We developed an explicit equation of state (EOS) for small non polar molecules by means of an effective two-body potential. The average effect of three-body forces was incorporated as a perturbation, which results in rescaled values for the parameters of the two-body potential. These values replace the original ones in the EOS corresponding to the two-body interaction. We applied this procedure to the heavier noble gases and used a modified Kihara function with an effective Axilrod-Teller-Muto (ATM) term to represent the two- and three-body forces. We also performed molecular dynamics simulations with two- and three-body forces. There was good agreement between predicted, simulated, and experimental thermodynamic properties of neon, argon, krypton, and xenon, up to twice the critical density and up to five times the critical temperature. In order to achieve 1% accuracy of the pressure at liquid densities, the EOS must incorporate the effect of ATM forces. The ATM factor in the rescaled two-body energy is most important at temperatures around and lower than the critical one. Nonetheless, the rescaling of two-body diameter cannot be neglected at liquid-like densities even at high temperature. This methodology can be extended straightforwardly to deal with other two- and three-body potentials. It could also be used for other nonpolar substances where a spherical two-body potential is still a reasonable coarse-grain approximation. PMID:24320280

  13. Clathrate hydrates as a sink of noble gases in Titan's atmosphere

    E-print Network

    C. Thomas; O. Mousis; V. Ballenegger; S. Picaud

    2007-08-16

    We use a statistical thermodynamic approach to determine the composition of clathrate hydrates which may form from a multiple compound gas whose composition is similar to that of Titan's atmosphere. Assuming that noble gases are initially present in this gas phase, we calculate the ratios of xenon, krypton and argon to species trapped in clathrate hydrates. We find that these ratios calculated for xenon and krypton are several orders of magnitude higher than in the coexisting gas at temperature and pressure conditions close to those of Titan's present atmosphere at ground level. Furthermore we show that, by contrast, argon is poorly trapped in these ices. This trapping mechanism implies that the gas-phase is progressively depleted in xenon and krypton when the coexisting clathrate hydrates form whereas the initial abundance of argon remains almost constant. Our results are thus compatible with the deficiency of Titan's atmosphere in xenon and krypton measured by the {\\it Huygens} probe during its descent on January 14, 2005. However, in order to interpret the subsolar abundance of primordial Ar also revealed by {\\it Huygens}, other processes that occurred either during the formation of Titan or during its evolution must be also invoked.

  14. Noble gases, nitrogen, and methane from the deep interior to the atmosphere of Titan

    NASA Astrophysics Data System (ADS)

    Glein, Christopher R.

    2015-04-01

    Titan's thick N2-CH4 atmosphere is unlike any in the Solar System, and its origin has been shrouded in mystery for over half a century. Here, I perform a detailed analysis of chemical and isotopic data from the Cassini-Huygens mission to develop the hypothesis that Titan's (non-photochemical) atmospheric gases came from deep within. It is suggested that Titan's CH4, N2, and noble gases originated in a rocky core buried inside the giant satellite, and hydrothermal and cryovolcanic processes were critical to the creation of Titan's atmosphere. Mass balance and chemical equilibrium calculations demonstrate that all aspects of this hypothesis can be considered geochemically plausible with respect to contemporary observational, experimental, and theoretical knowledge. Specifically, I show that a rocky core with a bulk noble gas content similar to that in CI carbonaceous meteorites would contain sufficient 36Ar and 22Ne to explain their reported abundances. I also show that Henry's law constants for noble gases in relevant condensed phases can be correlated with the size of their atoms, which leads to expected mixing ratios for 84Kr (?0.2 ppbv) and 132Xe (?0.01 ppbv) that can explain why these species have yet to be detected (Huygens upper limit <10 ppbv). The outgassing of volatiles into Titan's atmosphere may be restricted by the stability of clathrate hydrates in Titan's interior. The noble gas geochemistry also provides significant new insights into the origin of N2 and CH4 on Titan, as I find that Ar and N2, and Kr and CH4 should exhibit similar phase partitioning behavior on Titan. One implication is that over 95% of Titan's N2 may still reside in the interior. Another key result is that the upper limit from the Huygens GC-MS on the Kr/CH4 ratio in Titan's atmosphere is far too low to be consistent with accretion of primordial CH4 clathrate, which motivates me to consider endogenic production of CH4 from CO2 as a result of geochemical reactions between liquid water and anhydrous rock (i.e., serpentinization). I show that sufficient CH4 can be produced to replenish Titan's atmosphere many times over in the face of irreversible photolysis and escape of CH4, which is consistent with the favored model of episodic cryovolcanic outgassing. There should also have been enough NH3 inside Titan so that its thermal decomposition in a hot rocky core can generate the observed atmospheric N2, and if correct this model would imply that Titan's interior has experienced vigorous hydrothermal processing. The similarity in 14N/15N between cometary NH3 and Titan's N2 is consistent with this picture. As for the isotopes in CH4, I show that their observed relative abundances can be explained by low-temperature (?20 °C) equilibria with liquid water (D/H) and the expected aqueous alteration mineral calcite (12C/13C), provided that nickel was present to catalyze isotopic exchange over geologic timescales. The present hypothesis is chemically and isotopically consistent with the Cassini-Huygens data, and it implies that the formation of Titan's atmosphere would have been an unavoidable consequence of volatile processing that was driven by the geophysical evolution of the interior. If all of the atmospheric N2 and CH4 have an endogenic origin, then no more than ?1.6 times the present amount of N2 can be lost by photochemistry and escape over the history of the atmosphere; and the D/H ratio in Titan's water should be much lower than that in Enceladus' plume. Given its important implications to the origin and evolution of volatiles in the outer Solar System, we must go back to Titan to acquire additional isotopic data that will allow more rigorous tests of models of the origin of its atmosphere. I predict the following isotopic ratios: 20Ne/22Ne ? 8.9, 36Ar/38Ar ? 5.3, (14N/15N)NH3 ? 130-170 , (12C/13C)CO2 ? 84 , (D/H)H2O ? 1.7 ×10-4 ; and recommend that future in situ instrumentation have the capability to measure the rare isotopologues of N2 and CH4, which represent previously unconsidered but potentially valuable sources o

  15. Lower mantle contribution to the genesis of carbonatites: the noble gases and carbon isotopic evidence

    NASA Astrophysics Data System (ADS)

    Mata, J.; Moreira, M.; Mourão, C.; Ader, M.; Doucelance, R.

    2009-04-01

    It has been demonstrated that only 20 to 40% of the subducted CO2 is extracted by decarbonatation of descending slab. This, and the fact that some carbonatites exhibit HIMU-like Pb, Nd and Sr isotopic signatures, led to models invoking a carbonatite origin by partial melting of ancient subducted carbonated oceanic crust. A recycled carbon origin for diamonds has also been suggested. However the mantle is the largest carbon reservoir of the Earth and a non-recycled (i.e. primordial) origin for the carbon in carbonatites cannot be discarded. Some of the Cape Verde oceanic carbonatites present low 4He/3He ratios (down to 46,700; R/Ra up to 15.5) demonstrating that they sample a reservoir characterized by low time-integrated (U+Th)/3He. Such a reservoir, being clearly distinct from the crust or from the upper mantle sampled by the 60 000 km long oceanic ridge system, is thought to be localized in the lower mantle. For continental carbonatites several authors has also interpreted noble gases isotopic compositions as reflecting the contribution of a reservoir with time-integrated (U+Th)/(3He, 22Ne) and 40K/36Ar lower than the upper mantle, thus endorsing the contribution of the lower mantle [1;2;3]. Some carbonatites are also characterized by 129Xe anomalies relatively to the air (129Xe/130Xe up to 6.94 in Cape Verde). Considering that the recycling of carbonates, eventually characterized by high Te and Ba contents, would with time increase simultaneously the 129Xe and 130Xe, the observed 129Xe anomalies cannot be explained by models calling upon crustal carbonate recycling. We interpret them in terms of an ancient mantle origin by decay of the now extinct 129I. Moreover, experimental work has demonstrated that crustal carbonates are unlikely to be transported to lower mantle depth levels as a consequence of its removal by melting reactions. Thus, all the above described lower mantle signals are indicative of a non-recycled, lower mantle, origin for carbon, unless we admit that, during ascent, deep-seated mantle plumes entrain recycled carbon from the upper mantle. Nevertheless many carbonatites are also characterized by ^13C values (-8.0 to -4.25 per mil in Cape Verde) lighter than those characterizing crustal inorganic carbonates, endorsing the role of primordial carbon to the genesis of carbonatites. Taking into account that a recycled origin for some carbonatites is inescapable from carbon and noble gases signatures [e.g. 4; 5] we conclude that multiple origins (recycled vs. primordial) are possible for the carbon involved in the generation of carbonatitic magmas. Sasada et al. (1997) - Geochim. Cosmochim. Acta, 61: 4219-4228 Marty et al. (1998)- Earth Planet. Sci. Lett., 164: 179-192 Tolstikhin et al. (2002) - Geochim. Cosmochim. Acta, 66: 881-901 Ray et al. (1999) - Earth Planet Sci. Lett., 170; 205-214 Basu & Murty (2006) - Chem. Geol., 234: 236-250 This is a contribution from the FCT/FEDER project PLINT (POCTI/CTA/45802/2002)

  16. Volatiles (H, C, N, O, noble gases) in comets as tracers of early solar system events (Invited)

    NASA Astrophysics Data System (ADS)

    Marty, B.

    2013-12-01

    Volatiles (H, C, N, O, noble gases) present the largest variations in their relative abundances and, importantly, in their isotopic ratios, among solar system elements. The original composition of the protosolar nebula has been investigated through the measurements of primitive meteorites and of in-situ (e.g. Galileo probe analysis of the Jupiter's atmosphere) and sample-return (Genesis, recovery and analysis of solar wind) missions. The protosolar gas was poor in deuterium, in 15N and in 17,18O. Variations among solar system reservoir reach several hundreds of percents for the D/H and 15N/14N ratios. These variations are possibly : (i) due to interactions between XUV photons of the proto-Sun and the-dust, (ii) result from low temperature ion-molecule reactions, or (iii) constitute an heritage on interstellar volatiles trapped in dust (e.g., organics). Likewise, noble gases are elementally and isotopically (1% per amu for xenon) fractionated with respect to the composition of the solar wind (our best proxy for the protosolar nebula composition). Cometary matter directly measured on coma, or in Stardust material, or in IDPs, seems to present among the largest heterogeneities in their stable isotope compositions but knowledge on their precise compositions of the different phases and species is partial and mosty lacking. Among the several important issues requiring a better knowledge of cometary volatiles are the origin(s) of volatile elements on Earth and Moon, on Mars and on Venus, understanding large scale circulation of matter between hot and frozen zones, and the possibility of interstellar heritage for organics. Critical measurements to be made by the next cometary missions include the value of the D/H ratio in water ice, in NH3 and organics. Nitrogen is particularly interesting as cometary HCN and CN are rich in 15N, but an isotoppe mass balance will require to measure the main host species (N2 ?). Noble gases are excellent tracers of physical processes, including the delivery of volatile elements onto planets and atmospheric escape processes, but their cometary inventory is almost not known. The only noble gas (helium and neon) measurement in cometary matter from Stardust suggests that they may be genetically linked to organic matter found in primitive meteorites rather than to the proto-solar gas. Trapping of noble gases in comets is an important issue not only for the physical conditions of cometary formation and evolution, but also for better understanding the possible contribution of cometary matter to Earth and Moon.

  17. Noble gases identify the mechanisms of fugitive gas contamination in drinking-water wells overlying the Marcellus and Barnett Shales

    PubMed Central

    Darrah, Thomas H.; Vengosh, Avner; Jackson, Robert B.; Warner, Nathaniel R.; Poreda, Robert J.

    2014-01-01

    Horizontal drilling and hydraulic fracturing have enhanced energy production but raised concerns about drinking-water contamination and other environmental impacts. Identifying the sources and mechanisms of contamination can help improve the environmental and economic sustainability of shale-gas extraction. We analyzed 113 and 20 samples from drinking-water wells overlying the Marcellus and Barnett Shales, respectively, examining hydrocarbon abundance and isotopic compositions (e.g., C2H6/CH4, ?13C-CH4) and providing, to our knowledge, the first comprehensive analyses of noble gases and their isotopes (e.g., 4He, 20Ne, 36Ar) in groundwater near shale-gas wells. We addressed two questions. (i) Are elevated levels of hydrocarbon gases in drinking-water aquifers near gas wells natural or anthropogenic? (ii) If fugitive gas contamination exists, what mechanisms cause it? Against a backdrop of naturally occurring salt- and gas-rich groundwater, we identified eight discrete clusters of fugitive gas contamination, seven in Pennsylvania and one in Texas that showed increased contamination through time. Where fugitive gas contamination occurred, the relative proportions of thermogenic hydrocarbon gas (e.g., CH4, 4He) were significantly higher (P < 0.01) and the proportions of atmospheric gases (air-saturated water; e.g., N2, 36Ar) were significantly lower (P < 0.01) relative to background groundwater. Noble gas isotope and hydrocarbon data link four contamination clusters to gas leakage from intermediate-depth strata through failures of annulus cement, three to target production gases that seem to implicate faulty production casings, and one to an underground gas well failure. Noble gas data appear to rule out gas contamination by upward migration from depth through overlying geological strata triggered by horizontal drilling or hydraulic fracturing. PMID:25225410

  18. Noble gases identify the mechanisms of fugitive gas contamination in drinking-water wells overlying the Marcellus and Barnett Shales.

    PubMed

    Darrah, Thomas H; Vengosh, Avner; Jackson, Robert B; Warner, Nathaniel R; Poreda, Robert J

    2014-09-30

    Horizontal drilling and hydraulic fracturing have enhanced energy production but raised concerns about drinking-water contamination and other environmental impacts. Identifying the sources and mechanisms of contamination can help improve the environmental and economic sustainability of shale-gas extraction. We analyzed 113 and 20 samples from drinking-water wells overlying the Marcellus and Barnett Shales, respectively, examining hydrocarbon abundance and isotopic compositions (e.g., C2H6/CH4, ?(13)C-CH4) and providing, to our knowledge, the first comprehensive analyses of noble gases and their isotopes (e.g., (4)He, (20)Ne, (36)Ar) in groundwater near shale-gas wells. We addressed two questions. (i) Are elevated levels of hydrocarbon gases in drinking-water aquifers near gas wells natural or anthropogenic? (ii) If fugitive gas contamination exists, what mechanisms cause it? Against a backdrop of naturally occurring salt- and gas-rich groundwater, we identified eight discrete clusters of fugitive gas contamination, seven in Pennsylvania and one in Texas that showed increased contamination through time. Where fugitive gas contamination occurred, the relative proportions of thermogenic hydrocarbon gas (e.g., CH4, (4)He) were significantly higher (P < 0.01) and the proportions of atmospheric gases (air-saturated water; e.g., N2, (36)Ar) were significantly lower (P < 0.01) relative to background groundwater. Noble gas isotope and hydrocarbon data link four contamination clusters to gas leakage from intermediate-depth strata through failures of annulus cement, three to target production gases that seem to implicate faulty production casings, and one to an underground gas well failure. Noble gas data appear to rule out gas contamination by upward migration from depth through overlying geological strata triggered by horizontal drilling or hydraulic fracturing. PMID:25225410

  19. Noble gases in submarine pillow basalt glasses from Loihi and Kilauea, Hawaii: A solar component in the Earth

    USGS Publications Warehouse

    Honda, M.; McDougall, I.; Patterson, D.B.; Doulgeris, A.; Clague, D.A.

    1993-01-01

    Noble gas elemental and isotopic abundances have been analysed in twenty-two samples of basaltic glass dredged from the submarine flanks of two currently active Hawaiian volcanoes, Loihi Seamount and Kilauea. Neon isotopic ratios are enriched in 20Ne and 21Ne by as much as 16% with respect to atmospheric ratios. All the Hawaiian basalt glass samples show relatively high 3He 4He ratios. The high 20Ne 22Ne values in some of the Hawaiian samples, together with correlations between neon and helium systematics, suggest the presence of a solar component in the source regions of the Hawaiian mantle plume. The solar hypothesis for the Earth's primordial noble gas composition can account for helium and neon isotopic ratios observed in basaltic glasses from both plume and spreading systems, in fluids in continental hydrothermal systems, in CO2 well gases, and in ancient diamonds. These results provide new insights into the origin and evolution of the Earth's atmosphere. ?? 1993.

  20. The solubility of the noble gases He, Ne, Ar, Kr, and Xe in water up to the critical point

    USGS Publications Warehouse

    Potter, R.W., II; Clynne, M.A.

    1978-01-01

    The solubility of the noble gases Ar, He, Ne, Kr, and Xe in pure water was measured from 298 to 561??K. These data in turn were extrapolated to the critical point of water, thus providing a complete set of Henry's law constants from 274 to 647??K when combined with the existing literature data. Equations describing the behavior of the Henry's law constants over this temperature range are also given. The data do not confirm extrapolations of empirical correlations based on low-temperature solubility data. ?? 1978 Plenum Publishing Corporation.

  1. Differentiated achondrites Asuka 881371, an angrite, and Divnoe: Noble gases, ages, chemical composition, and relation to other meteorites

    NASA Astrophysics Data System (ADS)

    Weigel, A.; Eugster, O.; Koeberl, C.; Krähenbühl, U.

    1997-01-01

    We present a study of the noble gas isotopic abundances in two achondrites, Divnoe and the Asuka 881371 angrite. For Divnoe, we also performed chemical analyses of the major elements and of some minor and trace elements that are relevant for the comparison with other meteorite types and for the interpretation of the noble gas data. Based on the cosmic-ray produced noble gases, an exposure age of 5.4 ± 0.7 Ma for Asuka 881371 was obtained. This ejection time from the parent asteroid differs from those of the other three angrites - Angra dos Reis (55.5 Ma), LEW 86010 (17.6 Ma), and LEW 87051 (?0.2 Ma). Whereas the U,Th- 4He, and K- 40Ar gas retention ages of Asuka 881371 are 3750 ± 1000 Ma and 3910 ± 500 Ma, respectively, we derive for the 244Pu- 136Xe system, a formation age of 4533 ± 40 Ma, which is contemporaneous with that of the other angrites Angra dos Reis and LEW 86010. For Divnoe the abundance patterns of the major lithophile, siderophile, refractory, and volatile elements, the isotopic abundance pattern for primordial trapped Xe, and the oxygen isotopes indicate that this unique meteorite is related to the brachinite achondrites. Assuming no pre-exposure to cosmic rays on the parent body, Divnoe's asteroid ejection event occurred 17.2 ± 2.3 Ma ago.

  2. Composition of solar wind noble gases released by surface oxidation of a metal separate from the Weston meteorite

    NASA Technical Reports Server (NTRS)

    Becker, R. H.; Pepin, R. O.

    1991-01-01

    The paper reports on a set of experiments intended to test the feasibility of determining elemental and isotopic ratios of the noble gases and nitrogen in the solar wind in metal separates from gas-rich ordinary chondrites. Helium, neon, and argon show clear evidence of a solar wind signature, while no solar component could be identified for xenon and nitrogen. Helium, neon, and argon elemental isotopic ratios appear to depend on depth within the metal grains. The ratios derived indicate that the Weston meteorite did not acquire its solar wind gases from a recent exposure to solar wind, but more probably at a time in the past similar to or even earlier than the exposure time of Apollo 17 breccias. The Ar-36/Ar-38 ratio, in tandem with other recent determinations of this value, indicates that the solar and terrestrial values can no longer be assumed to be equivalent.

  3. Groundwater mixing pattern and origin of salinization in the Azraq Oasis, Jordan, revealed by noble gases

    NASA Astrophysics Data System (ADS)

    Kaudse, Tillmann; Aeschbach-Hertig, Werner; Tuffaha, Randa; Bani-Khalaf, Refaat

    2014-05-01

    Azraq Oasis, located in the eastern Jordanian desert, is an important freshwater resource of the country. Shallow groundwater reserves are heavily exploited since the 1980s and in consequence the groundwater table dropped by about 25 m and important wetlands dried out. Furthermore, some wells of the major well field show an increasing mineralization over the past 20 years. The fact that only a few wells show this behavior is surprising since the wells are situated quite close together and are mostly drilled to the same depth. A previous study using conventional tracers did not yield a satisfactory explanation [1]. Application of dissolved noble gases reveals the complex mixing pattern leading to the very localized salinization within the well field. It is found that the wells affected by salinization 1) contain distinctly more radiogenic 4He than the other wells, indicating higher groundwater age, and 2) exhibit a significantly enhanced 3He/4He ratio, implying an influence of deep mantle fluids. Since the hydrogeologic system in the Azraq Oasis comprises of three aquifer systems, separated by poorly permeable layers and traversed by several deep fault systems, mantle influence is expected to be found in the deeper aquifers. The data, therefore, indicate upward leakage into the shallow aquifer. However, the saline middle aquifer is virtually free of mantle helium. To our knowledge, this is the first time a groundwater system is described where mantle helium is found in an aquifer lying on top of one which is free of mantle impact. This behavior can be explained by an upstream from an even deeper (and saline) source through a nearby conductive fault, while the groundwater flow direction in the middle aquifer is towards the fault and reversed in the shallow aquifer, towards the well field. This scheme explains how the mantle fluids (and also most probably the increased salinity) infiltrates into the shallow aquifer, but not why only few wells are affected. The shallow aquifer consists of chalky limestone and a far more permeable basalt shield on top. Because the boreholes of the well field have no casing, water is potentially abstracted from all depths. Initially, however, by far most water was abstracted from the basalt aquifer due to the different permeabilities. As the groundwater table dropped, the basalt layer fell progressively dry and subsequently more water from the deeper part of the shallow aquifer was incorporated into the well's discharge - which according to the presented scheme is affected by salt and mantle fluids. The local depletion depends strongly on the individual cone of depression around a borehole and, therefore, can explain the local occurrence of the salinization phenomenon. The admixing of deep groundwater is further supported by warmer discharge temperatures and other parameters. [1] Al-Momani et al. (2006), IAEA TecDoc 1507, 177-211

  4. Cosmogenic Records in 18 Ordinary Chondrites from the Dar Al Gani Region, Libya. 1; Noble Gases

    NASA Technical Reports Server (NTRS)

    Schultz, L.; Franke, L.; Welten, K. C.; Nishiizumi, K.; Jull, A. J. T.

    2003-01-01

    In the last decade thousands of meteorites have been recovered from hot deserts in the Sahara and Oman. One of the main meteorite concentration surfaces in the Sahara is the Dar al Gani plateau in Libya, which covers a total area of 8000 km2. More than 1000 meteorites have been reported from this area. The geological setting, meteorite pairings and the meteorite density of the Dar al Gani (DaG) field are described in more detail in [1]. In this work we report concentrations of the noble gas isotopes of He, Ne, Ar as well as 84Kr and 132Xe in 18 DaG meteorites. In a separate paper we will report the cosmogenic radionuclides [2]. We discuss the thermal history and cosmic-ray exposure (CRE) history of these meteorites, and evaluate the effects of the hot desert environment on the noble gas record.

  5. Quantifying magmatic, crustal, and atmospheric helium contributions to volcanic aquifers using all stable noble gases: Implications for magmatism and groundwater flow

    Microsoft Academic Search

    M. O. Saar; M. C. Castro; C. M. Hall; M. Manga; T. P. Rose

    2005-01-01

    We measure all stable noble gases (He, Ne, Ar, Kr, Xe) in spring waters in the Oregon Cascades volcanic arc and in eastern Oregon, USA. We show that in order to estimate magmatic helium (He) contributions it is critical to simultaneously consider He isotopic ratios, He concentrations, and mixing of He components. Our component mixing analysis requires consideration of all

  6. Analysis of groundwater dynamics in the complex aquifer system of Kazan Trona, Turkey, using environmental tracers and noble gases

    NASA Astrophysics Data System (ADS)

    Arslan, Sebnem; Yazicigil, Hasan; Stute, Martin; Schlosser, Peter; Smethie, William M.

    2015-02-01

    The Eocene deposits of Kazan Basin in Turkey contain a rare trona mineral which is planned to be extracted by solution mining. The complex flow dynamics and mixing mechanisms as noted from previous hydraulic and hydrochemical data need to be augmented with environmental tracer and noble gas data to develop a conceptual model of the system for the assessment of the impacts of the mining and to develop sustainable groundwater management policies throughout the area. The tracers used include the stable isotopes of water (?2H, ?18O), ?13C and 14C of dissolved inorganic carbon (DIC), tritium (3H), the chlorofluorocarbons CFC-11 and CFC-12, and the noble gases He and Ne. The system studied consists of three aquifers: shallow, middle, and deep. CFC data indicate modern recharge in the shallow system. The estimates of ages through 14C dating for the deeper aquifer system are up to 34,000 years. Helium concentrations cover a wide range of values from 5 × 10-8 to 1.5 × 10-5 cm3 STP/g. 3He/4He ratios vary from 0.09RA to 1.29RA (where RA is the atmospheric 3He/4He ratio of 1.384 × 10-6), the highest found in water from the shallow aquifer. Mantle-derived 3He is present in some of the samples indicating upward groundwater movement, possibly along a NE-SW-striking fault-like feature in the basin.

  7. Sequential two-photon double ionization of noble gases by circularly polarized XUV radiation

    NASA Astrophysics Data System (ADS)

    Gryzlova, E. V.; Grum-Grzhimailo, A. N.; Kuzmina, E. I.; Strakhova, S. I.

    2014-10-01

    Photoelectron angular distributions (PADs) and angular correlations between two emitted electrons in sequential two-photon double ionization (2PDI) of atoms by circularly polarized radiation are studied theoretically. In particular, the sequential 2PDI of the valence n{{p}6} shell in noble gas atoms (neon, argon, krypton) is analyzed, accounting for the first-order corrections to the dipole approximation. Due to different selection rules in ionization transitions, the circular polarization of photons causes some new features of the cross sections, PADs and angular correlation functions in comparison with the case of linearly polarized photons.

  8. Ionization and Fragmentation of Molecular Gases in Collisions with Mev/amu Heavy Ions.

    NASA Astrophysics Data System (ADS)

    Maurer, Richard Jay

    A detailed study of ionization and fragmentation in molecular gas targets by 2.75 MeV H^ {+} and 40 MeV Ar^{13+ } ions has been performed using the time-of -flight (TOF) method. Ionization of molecular gases by 2.75 MeV H^{+} ions results primarily in single and double ionization, and consequently, the fragmentation patterns are simple to interpret. Energetic highly-charged, heavy ions, such as 40 MeV Ar^ {13+}, were found to be very effective in producing multiple ionization in molecular gas targets either through direct ionization or electron capture. Multiply -charged molecular ions, which are typically very unstable, rapidly dissociate to yield a rich fragmentation pattern containing numerous atomic and molecular fragments. A two stage TOF mass spectrometer was designed, constructed and tested for application to the study of fragmentation in molecular gas targets. The TOF spectrometer was calibrated and optimized for resolution and space focussing using neon and argon gas targets. To verify the proper working conditions for the spectrometer, several experiments were performed using noble gas targets including coincidence measurements of the recoil ion charge state distributions with the post-collision charge states of a 40 MeV Ar ^{13+} beam. Partial cross sections for direct ionization, one-, two- and three-electron capture in neon and argon by 40 MeV Ar^{13+ } ions have been determined and compared to ion-atom collisions theories. The fragmentation patterns for several molecular gases from simple diatomics (N_2, O_2, CO, NO) and triatomics (CO _2, N_2O, NO_2, SO_2) to large polyatomics (C_2F _6, C_2H_4 F_2, SF_6 ) have been measured. The fragmentation patterns for molecular gases measured by the TOF method were found to be useful in providing information about the various pathways for unimolecular dissociation of multiply-charged molecular ions. Moreover, several useful quantities such as fragments yields and average kinetic energies were obtained from the TOF spectrum. Energetic fragments produced in the dissociation of a multiply-charged molecular ion were found to exhibit a characteristic split peak structure in the TOF spectrum, whereas less energetic fragments, such as central atoms in totally symmetric molecules, had very narrow peak widths in the TOF spectrum similar to those observed for noble gas recoil ions. A simple model is proposed to predict the lowest energy pre-dissociative state in multiply-charged molecular ions.

  9. High resolution diode laser spectroscopy of H2O spectra broadened by nitrogen and noble gases

    NASA Astrophysics Data System (ADS)

    Kapitanov, Venedikt A.; Osipov, Konstantin Yu.; Protasevich, Alexander E.; Ponurovskiy, Yakov Ya.

    2014-11-01

    The absorption spectra of pure H2O with mixtures of broadening gases N2, Ar, Xe, He, Ar and air have been measured in 1.39 m? spectral region by high resolution spectrometer based on diode laser (DFB NEL, Japan). For the processing of pure water spectra and it's mixtures with a different broadening gases in a wide pressure range we used a multispectrum fitting procedure developed at IAO. The program is based on a relatively simple Rautian-Sobel'man line profile and linear pressure dependence of the line profile parameters. H2O measured spectra bulk processing results in the retrieving of such line parameters: zero-pressure line center positions, intensities, self-broadening and self-shift coefficients of pure water, broadening and shift coefficients for other gases which are describes the experiment with the minimum residuals in a wide pressure range.

  10. MRI of the lung gas-space at very low-field using hyperpolarized noble gases

    NASA Technical Reports Server (NTRS)

    Venkatesh, Arvind K.; Zhang, Adelaide X.; Mansour, Joey; Kubatina, Lyubov; Oh, Chang Hyun; Blasche, Gregory; Selim Unlu, M.; Balamore, Dilip; Jolesz, Ferenc A.; Goldberg, Bennett B.; Albert, Mitchell S.

    2003-01-01

    In hyperpolarized (HP) noble-gas magnetic resonance imaging, large nuclear spin polarizations, about 100,000 times that ordinarily obtainable at thermal equilibrium, are created in 3He and 129Xe. The enhanced signal that results can be employed in high-resolution MRI studies of void spaces such as in the lungs. In HP gas MRI the signal-to-noise ratio (SNR) depends only weakly on the static magnetic field (B(0)), making very low-field (VLF) MRI possible; indeed, it is possible to contemplate portable MRI using light-weight solenoids or permanent magnets. This article reports the first in vivo VLF MR images of the lungs in humans and in rats, obtained at a field of only 15 millitesla (150 Gauss).

  11. Laboratory simulation of meteoritic noble gases. II - Sorption of xenon on carbon: Etching and heating experiments

    NASA Technical Reports Server (NTRS)

    Zadnik, M. G.; Wacker, J. F.; Lewis, R. S.

    1985-01-01

    The release of trapped Xe from amorphous-C phases of meteorites is simulated experimentally by HNO3 etching of carbon-black and pyrolyzed polyvinylidene chloride samples exposed to Xe-127 for 0.5-240 h at 100-1000 C and then degassed for 9 h or more at the same temperatures, as reported by Wacker et al. (1985). The results are presented in tables and graphs and characterized in detail. Samples exposed at 100-200 C are found to lose most of their Xe after etching to a depth of only about 20 pm, while those exposed at 800-1000 C exhibit a second more tightly bound component extending to a depth of 3 nm, indicative of diffusion of Xe during exposure and resembling planetary Xe. The higher noble-gas concentrations measured in meteorites are attributed to rate-controlled Xe uptake over a long period in the solar nebula.

  12. Light noble gases in 12 meteorites from the Omani desert, Australia, Mauritania, Canada, and Sweden

    NASA Astrophysics Data System (ADS)

    Leya, I.; Ammon, K.; Cosarinsky, M.; Dalcher, N.; Gnos, E.; Hofmann, B.; Huber, L.

    2013-08-01

    We measured the concentrations and isotopic compositions of He, Ne, and Ar in 14 fragments from 12 different meteorites: three carbonaceous chondrites, six L chondrites (three most likely paired), one H chondrite, one R chondrite, and one ungrouped chondrite. The data obtained for the CV3 chondrites Ramlat as Sahmah (RaS) 221 and RaS 251 support the hypothesis of exposure age peaks for CV chondrites at approximately 9 Ma and 27 Ma. The exposure age for Shi?r 033 (CR chondrite) of 7.3 Ma is also indicative of a possible CR chondrite exposure age peak. The three L chondrites Jiddat al Harasis (JaH) 091, JaH 230, and JaH 296, which are most likely paired, fall together with Hallingeberg into the L chondrite exposure age peak of approximately 15 Ma. The two L chondrites Shelburne and Lake Torrens fall into the peaks at approximately 40 Ma and 5 Ma, respectively. The ages for Bassikounou (H chondrite) and RaS 201 (R chondrite) are approximately 3.5 Ma and 5.8 Ma, respectively. Six of the studied meteorites show clear evidence for 3He diffusive losses, the deficits range from approximately 17% for one Lake Torrens aliquot to approximately 45% for RaS 211. The three carbonaceous chondrites RaS 221, RaS 251, and Shi?r 033 all have excess 4He, either of planetary or solar origin. However, very high 4He/20Ne ratios occur at relatively low 20Ne/22Ne ratios, which is unexpected and needs further study. The measured 40Ar ages fit well into established systematics. They are between 2.5 and 4.5 Ga for the carbonaceous chondrites, older than 3.6 Ga for the L and H chondrites, and about 2.4 Ga for the R chondrite as well as for the ungrouped chondrite. Interestingly, none of our studied L chondrites has been degassed in the 470 Ma break-up event. Using the amount of trapped 36Ar as a proxy for noble gas contamination due to terrestrial weathering we are able to demonstrate that the samples studied here are not or only very slightly affected by terrestrial weathering (at least in terms of their noble gas budget).

  13. JOURNAL DE PHYSIQUE Colloque C7, suppl&menl; au n07, Tome 40, JuiZZet 1979, pa@ C7-6 3 MONTE CARL0 SIMULATIONS OF ELECTRON DRIFT VELOCITIES INTHE NOBLE GASES AND THEIR MIXTURES

    E-print Network

    Boyer, Edmond

    components. Then for each collision a in neutron counters under reactor conditions. However, random number R05AAF(Y), breakaway occurred in all the noble gases (including even the case of a constant 6 Article

  14. A density functional theory study of magneto-electric Jones birefringence of noble gases, furan homologues, and mono-substituted benzenes

    SciTech Connect

    Fahleson, Tobias; Norman, Patrick, E-mail: panor@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Coriani, Sonia, E-mail: coriani@units.it [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, I-34127 Trieste (Italy); Rizzo, Antonio, E-mail: rizzo@ipcf.cnr.it [CNR - Consiglio Nazionale delle Ricerche, Istituto per i Processi Chimico Fisici (IPCF-CNR), UOS di Pisa, I-56124 Pisa (Italy); Rikken, Geert L. J. A., E-mail: geert.rikken@lncmi.cnrs.fr [Laboratoire National des Champs Magnétiques Intenses, UPR3228, CNRS/INSA/UJF/UPS, Toulouse and Grenoble (France)

    2013-11-21

    We report on the results of a systematic ab initio study of the Jones birefringence of noble gases, of furan homologues, and of monosubstituted benzenes, in the gas phase, with the aim of analyzing the behavior and the trends within a list of systems of varying size and complexity, and of identifying candidates for a combined experimental/theoretical study of the effect. We resort here to analytic linear and nonlinear response functions in the framework of time-dependent density functional theory. A correlation is made between the observable (the Jones constant) and the atomic radius for noble gases, or the permanent electric dipole and a structure/chemical reactivity descriptor as the para Hammett constant for substituted benzenes.

  15. Gradient-induced Longitudinal Relaxation of Hyperpolarized Noble Gases in the Fringe Fields of Superconducting Magnets Used for Magnetic Resonance

    PubMed Central

    Zheng, Wangzhi; Cleveland, Zackary I.; Möller, Harald E.; Driehuys, Bastiaan

    2010-01-01

    When hyperpolarized noble gases are brought into the bore of a superconducting magnet for magnetic resonance imaging (MRI) or spectroscopy studies, the gases must pass through substantial field gradients, which can cause rapid longitudinal relaxation. In this communication, we present a means of calculating this spatially dependent relaxation rate in the fringe field of typical magnets. We then compare these predictions to experimental measurements of 3He relaxation at various positions near a medium-bore 2-T small animal MRI system. The calculated and measured relaxation rates on the central axis of the magnet agree well and show a maximum 3He relaxation rate of 3.83 × 10?3 s?1 (T1 = 4.4 min) at a distance of 47 cm from the magnet isocenter. We also show that if this magnet were self-shielded, its minimum T1 would drop to 1.2 min. In contrast, a typical self-shielded 1.5-T clinical MRI scanner will induce a minimum on-axis T1 of 12 min. Additionally, we show that the cylindrically symmetric fields of these magnets enable gradient-induced relaxation to be calculated using only knowledge of the on-axis longitudinal field, which can either be measured directly or calculated from a simple field model. Thus, while most MRI magnets employ complex and proprietary current configurations, we show that their fringe fields and the resulting gradient induced relaxation are well approximated by simple solenoid models. Finally, our modeling also demonstrates that relaxation rates can increase by nearly an order of magnitude at radial distances equivalent to the solenoid radius. PMID:21134771

  16. Heats of interaction of hydrogen with gold and platinum powders and its effect on the subsequent adsorptions of oxygen and noble gases

    NASA Astrophysics Data System (ADS)

    Groszek, Aleksander J.; Lalik, Erwin; Haber, Jerzy

    2010-06-01

    Exposure of pure gold powders to hydrogen flow at 125 °C and atmospheric pressure causes heat evolution accompanied by hydrogen adsorption. The exposure takes place in a flow-through microcalorimeter, in which the metal powders are purged by nitrogen flow used as an inert carrier gas. The adsorbed hydrogen is slowly desorbed by nitrogen flow. The heats of hydrogen adsorption and its uptake by the gold powder are greatly increased by its sequential treatments with micromole quantities of oxygen and noble gases, such as helium and argon. This increase does not take place if the gold treatment is confined only to oxygen, or only to pure noble gases. The radically increased hydrogen adsorption by gold is caused by a combination of its treatments with oxygen and the noble gases. Similar results were obtained with pure platinum powder exposed to hydrogen at room temperatures. Gold powder containing adsorbed hydrogen reacts very strongly with molecular oxygen/argon mixtures, generating heats of adsorption several times higher than the heat of formation of water. The heat evolution is very rapid and is not accompanied by the formation of water. These intense interactions are not observed after complete desorption of hydrogen from the gold surfaces.

  17. Stratification of discharge in noble gases from the viewpoint of the discrete dynamics

    NASA Astrophysics Data System (ADS)

    Golubovskii, Yu.; Pelyukhova, E.; Sigeneger, F.; Nekuchaev, V.

    2015-03-01

    Based on the analysis of electron phase trajectories in sinusoidal electric fields, a new point of view on discharge stratification is proposed. It is shown that the positive column can be considered as a spatial resonator in which electric fields with a fundamental period length LS or higher mode length q/p LS establish, where p and q are integers and p > q. The fundamental mode length LS is equivalent to the distance on which electrons gain energy equal to the lowest excitation threshold. This distance determines a length of the S-striation. Unlike kinetic theory, in the presented model resonance properties of the discharge column are not connected with elastic collision energy losses. A point map is used to obtain the resonance trajectories of electrons in the phase plane. Stable points for the positions of inelastic collisions in the resonance trajectories have been found at the positions of field maxima in the case of integer ratios p/q . For non-integer ratios p/q , multiple resonance trajectories arise according to a more complex stability criterion. From this point of view, S-, P-, and R-striations in noble gas discharges can be explained. Due to energy losses in elastic collisions, initial electron energy distribution functions converge to the resonance trajectories (the so-called "bunch effect"). The findings of the discrete model agree with results of kinetic theory and experiment. The new approach avoids difficulties of the kinetic theory in the case of exceptionally large relaxation lengths which can even exceed the positive column length.

  18. Experimental verification of the Boltzmann relation in confined plasmas: Comparison of noble and molecule gases

    SciTech Connect

    Lee, Hyo-Chang; Hwang, Hye-Ju; Kim, Young-Cheol; Kim, June Young; Kim, Dong-Hwan; Chung, Chin-Wook [Department of Electrical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

    2013-03-15

    Experimental verification of the Boltzmann relation is performed in argon and oxygen gas inductively coupled plasmas from the measurements of both the spatial electron currents (as a fluid approach) and the electron energy probability functions (EEPFs, as a kinetic approach). At a low gas pressure of 10 mTorr, the measured electron currents are spatially uniform, and the EEPFs in the total electron energy scale are identical, which indicate that the Boltzmann relation is valid at both the argon and oxygen gases. As the gas pressure increases to 30-40 mTorr, however, the Boltzmann relation is broken in the oxygen gas discharge, while the Boltzmann relation is still valid in the argon gas discharge. This different variation in the oxygen gas discharge is mainly due to the presence of various inelastic collisions in the entire electron energy region, which causes the transition of the electron kinetics from a non-local to a local regime.

  19. Conductance isotherms for adsorption of noble gases on individual single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Dzyubenko, Boris; Lee, Hao-Chun; Vilches, Oscar; Cobden, David

    2012-02-01

    Using transistors made from suspended carbon nanotubes allows one to probe the interaction of adsorbed atoms and molecules with the carbon substrate electrons. We have studied the effects of adsorbing He, Ne, Ar, Kr, Xe, and other gases on the electrical properties of individual suspended single-walled nanotubes, as a function of pressure and temperature. The conductance changes measurably, and sometimes dramatically, as a monolayer forms and undergoes phase transitions. It yields complementary information to the coverage, which is obtained from the mass shift in the natural vibrational frequency of the nanotube. For example, measurements below the 2D critical point show nonmonotonic features and fluctuations heralding the first-order phase transition. Conductance changes can be measured on a timescale of milliseconds, permitting studies of the dynamics of the monolayer. In the nonlinear regime we observe features in the I-V characteristics as phase transitions are induced by the current and nonequilibrium stationary states occur.

  20. Composition of solar flare noble gases preserved in meteorite parent body regolith.

    PubMed

    Rao, M N; Garrison, D H; Bogard, D D; Badhwar, G; Murali, A V

    1991-11-01

    The isotopic composition (long-term average) of solar flare (SF) Ne has been determined by three isotope correlation techniques applied to data measured on chemically etched pyroxene separates prepared from the Kapoeta meteorite, which is known to contain implanted solar gases. The SF 20Ne/22Ne ratio obtained is 11.6 +/- 0.2 and confirms previous determinations of this SF ratio in lunar and meteoritic samples. The same SF Ne composition is also obtained by applying an ordinate intercept technique to the same data set. The ordinate intercept technique was also applied to the Ar and He data, on which the three-isotope correlation technique cannot be applied. The isotopic composition of SF Ar and SF He so obtained are SF 36Ar/38Ar = 4.9 +/- 0.1 and SF 4He/3He = 3800 +/- 200, which are significantly different from the solar wind (SW) Ar and SW He values of approximately 5.35 and approximately 2500, respectively. Correlation between 20Ne/22Ne and 36Ar/38Ar for the same data set also gives a similar SF 36Ar/38Ar ratio of 4.8 +/- 0.2. The determined SF He, Ne and Ar isotopic ratios differ from those in SW by 52%, 17% and 9%, respectively, but the elemental compositions of 4He/36Ar and 20Ne/36Ar do not show obvious differences between SF and SW. The concentration of the SF component in Kapoeta pyroxenes is approximately 20% that of the SW component, which is orders of magnitude higher than expected from SW and SF proton flux measurements. Variations in elemental and isotopic composition of He, Ne and Ar in SF relative to SW are found to correlate well with a (Z/A)2 dependence, indicating a rigidity-dependent particle spectrum in solar flares. PMID:11538179

  1. Environmental isotopes and noble gases in the deep aquifer system of Kazan Trona Ore Field, Ankara, central Turkey and links to paleoclimate

    NASA Astrophysics Data System (ADS)

    Arslan, Sebnem; Yazicigil, Hasan; Stute, Martin; Schlosser, Peter

    2013-03-01

    Environmental isotopes and noble gases in groundwater samples from the Kazan Trona Ore Field are studied to establish the temperature change between the Holocene and the late Pleistocene. Noble gas temperatures (NGTs) presented in this study add an important facet to the global paleotemperature map in the region between Europe and North Africa. The groundwater system under investigation consists of three different aquifers named shallow, middle and deep in which ?18O and ?2H vary from - 8.10‰ to - 12.80‰ and from - 60.89‰ to - 92.60‰ VSMOW, respectively. The average isotopic depletion between unconfined and confined parts of the system is - 2.5‰ in ?18O and - 20‰ in ?2H. It is not possible to explain this depletion solely with the elevation effect. Recharge temperatures derived from dissolved atmospheric noble gases reflect the current average yearly ground temperatures (13°C) for samples collected near the recharge area but are 3 to 8°C lower than today's temperatures in the deep aquifer system. Low 14C activities and high He excesses in the confined parts of the aquifer system suggest that the water in the deep aquifer was recharged during the last Pleistocene under considerably cooler climatic conditions.

  2. The solvation radius of silicate melts based on the solubility of noble gases and scaled particle theory

    SciTech Connect

    Ottonello, Giulio, E-mail: giotto@dipteris.unige.it [DISTAV, Università di Genova, Corso Europa 26, 16132 Genova (Italy)] [DISTAV, Università di Genova, Corso Europa 26, 16132 Genova (Italy); Richet, Pascal [Institut de Physique du Globe, Rue Jussieu 2, 75005 Paris (France)] [Institut de Physique du Globe, Rue Jussieu 2, 75005 Paris (France)

    2014-01-28

    The existing solubility data on noble gases in high-temperature silicate melts have been analyzed in terms of Scaling Particle Theory coupled with an ab initio assessment of the electronic, dispersive, and repulsive energy terms based on the Polarized Continuum Model (PCM). After a preliminary analysis of the role of the contracted Gaussian basis sets and theory level in reproducing appropriate static dipole polarizabilities in a vacuum, we have shown that the procedure returns Henry's law constants consistent with the values experimentally observed in water and benzene at T = 25?°C and P = 1 bar for the first four elements of the series. The static dielectric constant (?) of the investigated silicate melts and its optical counterpart (?{sup ?}) were then resolved through the application of a modified form of the Clausius-Mossotti relation. Argon has been adopted as a probe to depict its high-T solubility in melts through an appropriate choice of the solvent diameter ?{sub s}, along the guidelines already used in the past for simple media such as water or benzene. The ?{sub s} obtained was consistent with a simple functional form based on the molecular volume of the solvent. The solubility calculations were then extended to He, Ne, and Kr, whose dispersive and repulsive coefficients are available from theory and we have shown that their ab initio Henry's constants at high T reproduce the observed increase with the static polarizability of the series element with reasonable accuracy. At room temperature (T = 25?°C) the calculated Henry's constants of He, Ne, Ar, and Kr in the various silicate media predict higher solubilities than simple extrapolations (i.e., Arrhenius plots) based on high-T experiments and give rise to smooth trends not appreciably affected by the static polarizabilities of the solutes. The present investigation opens new perspectives on a wider application of PCM theory which can be extended to materials of great industrial interest at the core of metallurgical processes, ceramurgy, and the glass industry.

  3. Low-pressure adsorption of Ar, Kr, and Xe on carbonaceous materials (kerogen and carbon blacks), ferrihydrite, and montmorillonite: Implications for the trapping of noble gases onto meteoritic matter

    NASA Astrophysics Data System (ADS)

    Marrocchi, Yves; Razafitianamaharavo, Angelina; Michot, Laurent J.; Marty, Bernard

    2005-05-01

    Noble gases trapped in meteorites are tightly bound in a carbonaceous carrier labeled "phase Q." Mechanisms having led to their retention in this phase or in its precursors are poorly understood. To test physical adsorption as a way of retaining noble gases into precursors of meteoritic materials, we have performed adsorption experiments for Ar, Kr, and Xe at low pressures (10 -4 mbar to 500 mbar) encompassing pressures proposed for the evolving solar nebula. Low-pressure adsorption isotherms were obtained for ferrihydrite and montmorillonite, both phases being present in Orgueil (CI), for terrestrial type III kerogen, the best chemical analog of phase Q studied so far, and for carbon blacks, which are present in phase Q and can be considered as possible precursors. Based on adsorption data obtained at low pressures relevant to the protosolar nebula, we propose that the amount of noble gases that can be adsorbed onto primitive materials is much higher than previously inferred from experiments carried out at higher pressures. The adsorption capacity increases from kerogen, carbon blacks, montmorillonite to ferrihydrite. Because of its low specific surface area, kerogen can hardly account for the noble gas inventory of Q. Carbon blacks in the temperature range 75 K-100 K can adsorb up to two orders of magnitude more noble gases than those found in Q. Irreversible trapping of a few percent of noble gases adsorbed on such materials could represent a viable process for incorporating noble gases in phase Q precursors. This temperature range cannot be ruled out for the zone of accretion of the meteorite precursors according to recent astrophysical models and observations, although it is near the lower end of the temperatures proposed for the evolving solar nebula.

  4. Regional groundwater focusing of nitrogen and noble gases into the Hugoton-Panhandle giant gas field, USA

    NASA Astrophysics Data System (ADS)

    Ballentine, Chris J.; Sherwood Lollar, Barbara

    2002-07-01

    The Hugoton-Panhandle giant gas field, located across SW Kansas and the Texas and Oklahoma panhandles in the USA, is the case type example of high nitrogen concentrations in a natural gas being linked with high helium concentrations. We collected 31 samples from producing wells in a north-south traverse of the 350-km-long field. The samples reflect the previously observed north-south change in 4He/N 2, with values changing from 0.020 to 0.049 respectively. 3He/ 4He, 21Ne/ 22Ne, and 40Ar/ 36Ar vary between 0.14-0.25 Ra, 0.0373-0.0508, and 818-1156 respectively, and are caused by quantifiable contributions from mantle, crustal, and atmosphere-derived sources. The atmosphere-derived 20Ne/ 36Ar ratios are indistinguishable from groundwater values. The crustal 4He/ 21Ne* and 4He/ 40Ar* ratios show a 60% excess of 4He compared to predicted production ratios in the crust and are typical of noble gases released from the shallow crust. The mantle 3He/N 2 and groundwater-recharge 36Ar/N 2 ratios enable us to rule out significant magmatic or atmosphere contributions to the gas field N 2, which is dominantly crustal in origin. Correlated 20Ne/N 2 and 4He/N 2 shows mixing between two distinct crustal N 2 components. One N 2 component (N 2*) is associated with the crustal 4He and groundwater-derived 20Ne, and the other with no resolvable noble gas contribution. Measured ? 15N N 2 values vary from +2.7‰ to +9.4‰. The N 2* and non-He-associated N 2 endmembers are inferred to have ? 15N N 2 = -3‰ and +13‰ and contribute from between 25-60% and 75-40% of the nitrogen respectively. The non-He-associated nitrogen is probably derived from relatively mature organic matter in the sedimentary column. The ? 15N N 2* value is not compatible with a crystalline or high-grade metamorphic source and, similar to the 4He, is inferred to be from a shallow or low metamorphic-grade source rock. 4He mass balance requires a regional crustal source, its association with significant magmatic 3He pointing to a tectonically active source to the west of the Hugoton system. The volume of groundwater required to source the 20Ne in the gas field demonstrates the viability of the groundwater system in providing the collection, transport, and focusing mechanism for the 4He and N 2*. The N 2*/ 20Ne ratio shows that the N 2* transport must be in the aqueous phase, and that the degassing mechanism is probably contact between the regional groundwater system and the preexisting reservoir hydrocarbon gas phase.

  5. Effect of heavy noble gas ion irradiation on terahertz emission efficiency of InP (100) and (111) crystal planes

    NASA Astrophysics Data System (ADS)

    Radhanpura, K.; Lewis, R. A.; Sirbu, L.; Enachi, M.; Tiginyanu, I. M.; Skuratov, V. A.

    2014-09-01

    Emission of terahertz (THz) electromagnetic radiation from heavily-doped (5 × 1018 cm-3) (100) and (111) InP bulk materials and nanoporous honeycomb membranes, irradiated with heavy noble gas (Kr and Xe) ions, is presented. Irradiating samples with Kr or Xe improves THz emission efficiency. For (111) samples, as for unirradiated samples, the irradiated porous structures generate more THz radiation than their bulk counterparts. On the other hand, in contrast to unirradiated (100) samples, the irradiated (100) samples show a decrease in THz emission with porosity. We attribute this behaviour to changes in the local electric field due to the combined effect of the irradiation and nanoporosity.

  6. Noble gases in lunar anorthositic rocks 60018 and 65315 - Acquisition of terrestrial krypton and xenon indicating an irreversible adsorption process

    Microsoft Academic Search

    S. Niedermann; O. Eugster

    1992-01-01

    Results are presented from noble gas analyses of the 60018 and 65315 lunar anorthositic breccias and from experiments designed to determine whether the atmospheric contamination is the only source of the terrestriallike Xe in lunar samples (and, if so, what is the nature of the contaminating process). Results clearly show that the anorthositic material was contaminated both by Kr and

  7. Heavy noble gases in solar wind delivered by Genesis mission Alex Meshik a,

    E-print Network

    multiplier mass- spectrometer and an intricate low-blank laser extraction system capable of handling in the SW, so little modification to current mass spectrometry was needed to perform these isotopic analyses, with the exception of changes needed to handle the large concentrations of solar wind hydrogen. He and Ne isotopes

  8. Noble gases in submarine pillow basalt glasses from Loihi and Kilauea, Hawaii - A solar component in the Earth

    Microsoft Academic Search

    Masahiko Honda; Ian McDougall; Desmond B. Patterson; Anthony Doulgeris; David A. Clague

    1993-01-01

    Noble gas elemental and isotopic abundances have been analyzed in 22 samples of basaltic glass dredged from the submarine flanks of two currently active Hawaiian volcanoes, Loihi Seamount and Kilauea. Neon isotopic ratios are enriched in Ne-20 and Ne-21 by as much as 16 percent with respect to atmospheric ratios. All the Hawaiian basalt glass samples show relatively high He-3\\/He-4

  9. Noble Gases in Iddingsite from the Lafayette Meteorite: Evidence for Liquid Water on Mars in the Last Few Hundred Million Years

    NASA Technical Reports Server (NTRS)

    Swindle, T. D.; Treiman, A. H.; Lindstrom, D. J.; Brkland, M. K.; Cohen, B. A.; Grier, J. A.; Li, B.; Olson, E. K.

    2000-01-01

    We analyzed noble gases from 18 samples of weathering products ("iddingsite") from the Lafayette meteorite. Potassium-argon ages of 12 samples range from near zero to 670 +/- 91 Ma. These ages confirm the martian origin of the iddingsite, but it is not clear whether any or all of the ages represent iddingsite formation as opposed to later alteration or incorporation of martian atmospheric Ar-40. In any case, because iddingsite formation requires liquid water, this data requires the presence of liquid water near the surface of Mars at least as recently as 1300 Ma ago, and probably as recently as 650 Ma ago. Krypton and Xe analysis of a single 34 microg sample indicates the presence of fractionated martian atmosphere within the iddingsite. This also confirms the martian origin of the iddingsite. The mechanism of incorporation could either be through interaction with liquid water during iddingsite formation or a result of shock implantation of adsorbed atmospheric gas.

  10. Coexistence and interfacial properties of a triangle-well mimicking the Lennard-Jones fluid and a comparison with noble gases

    NASA Astrophysics Data System (ADS)

    Bárcenas, M.; Reyes, Y.; Romero-Martínez, A.; Odriozola, G.; Orea, P.

    2015-02-01

    Coexistence and interfacial properties of a triangle-well (TW) fluid are obtained with the aim of mimicking the Lennard-Jones (LJ) potential and approach the properties of noble gases. For this purpose, the scope of the TW is varied to match vapor-liquid densities and surface tension. Surface tension and coexistence curves of TW systems with different ranges were calculated with replica exchange Monte Carlo and compared to those data previously reported in the literature for truncated and shifted (STS), truncated (ST), and full Lennard-Jones (full-LJ) potentials. We observed that the scope of the TW potential must be increased to approach the STS, ST, and full-LJ properties. In spite of the simplicity of TW expression, a remarkable agreement is found. Furthermore, the variable scope of the TW allows for a good match of the experimental data of argon and xenon.

  11. Coexistence and interfacial properties of a triangle-well mimicking the Lennard-Jones fluid and a comparison with noble gases.

    PubMed

    Bárcenas, M; Reyes, Y; Romero-Martínez, A; Odriozola, G; Orea, P

    2015-02-21

    Coexistence and interfacial properties of a triangle-well (TW) fluid are obtained with the aim of mimicking the Lennard-Jones (LJ) potential and approach the properties of noble gases. For this purpose, the scope of the TW is varied to match vapor-liquid densities and surface tension. Surface tension and coexistence curves of TW systems with different ranges were calculated with replica exchange Monte Carlo and compared to those data previously reported in the literature for truncated and shifted (STS), truncated (ST), and full Lennard-Jones (full-LJ) potentials. We observed that the scope of the TW potential must be increased to approach the STS, ST, and full-LJ properties. In spite of the simplicity of TW expression, a remarkable agreement is found. Furthermore, the variable scope of the TW allows for a good match of the experimental data of argon and xenon. PMID:25702023

  12. Solubility investigations in support of ultrasensitive noble gas detector development.

    SciTech Connect

    Gross, K. C.

    1998-08-05

    Argonne National Laboratory (ANL) and the University of Cincinnati (UC) have been developing a new class of ultrasensitive noble gas detectors that are based upon the ANL discovery that corn oil has a high affinity for heavy noble gas absorption at room temperature, but releases the noble gases with warming or by other low-energy-input means. Environmental applications for this new class of fluid-based detectors include ultrahigh sensitivity radioxenon detectors for Comprehensive Test Ban Treaty Surveillance, improved fission gas detectors for enhanced environmental surveillance in the vicinity of DOE, DOD, and NRC-licensed facilities, and improved integrating Rn detectors for earthquake prediction. The purpose of the present paper is to present the results of theoretical and experimental investigations into the solubility phenomena of heavy noble gases (Rn, Xe, and Kr) in triglyceride oils. It is the authors' intention that the findings presented herein may be used to guide future selection, development, and refinement of vegetable and other hydrocarbon oils to bring further enhancements to noble gas detection efficiencies.

  13. Large isotopic anomalies of Si, C, N and noble gases in interstellar silicon carbide from the Murray meteorite

    NASA Astrophysics Data System (ADS)

    Zinner, E.; Ming, T.; Anders, E.

    1987-12-01

    Primitive meteorites contain several noble gas components with anomalous isotopic compositions which imply that they - and their solid 'carrier' phases - are of exotic, pre-solar origin. The authors found that minor fractions of the Murray meteorite contain two minerals not previously seen in meteorites: silicon carbide and an amorphous Si-O phase. They report ion microprobe analyses of these phases which reveal very large isotopic anomalies in silicon, nitrogen and carbon, exceeding the highest anomalies previously measured by factors of up to ?50. It is concluded that these phases are circumstellar grains from carbon-rich stars, whose chemical inertness allowed them to survive in exceptionally well-preserved form.

  14. Cold and trapped metastable noble gases LaserLaB Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands

    E-print Network

    Paris-Sud XI, Université de

    gases 29 A. Reflection of slow metastable atoms from surfaces 29 B. Birth and death of a Bose-Atom Optics Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 and detection 4 A. Discharge sources 4 B. Intense and slow beams of metastable atoms 5 C. Magneto

  15. Ionization and Fragmentation of Molecular Gases in Collisions with Mev\\/amu Heavy Ions

    Microsoft Academic Search

    Richard Jay Maurer

    1988-01-01

    A detailed study of ionization and fragmentation in molecular gas targets by 2.75 MeV H^ {+} and 40 MeV Ar^{13+ } ions has been performed using the time-of -flight (TOF) method. Ionization of molecular gases by 2.75 MeV H^{+} ions results primarily in single and double ionization, and consequently, the fragmentation patterns are simple to interpret. Energetic highly-charged, heavy ions,

  16. Noble Gases in the Monahans Chondrite and Halite: Ar-39 - Ar-40 Age, Space Exposure Age, Trapped Solar Gases, and Neutron Fluence

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.; Garrison, Daniel H.

    2000-01-01

    In the Monahans H5 chondrite, Zolensky et al. report the first occurrence of grains of halite (NaCl), which contain minor sylvite (KCl) and tiny inclusions of liquid water. Here we report Ar-39 - Ar-40 ages of Monahans light (4.53 Ga) and dark phases and of the halite (>4.33 Ga). We report the presence of trapped solar gases in the dark phase, demonstrating that it represents a prior regolith on the Monahans parent body, We also report the cosmic-ray exposure age of Monahans and the neutron fluence experienced by the regolith component. Because the halite grains are apparently located only in the regolith phase, they may have formed by early hydrous activity within the Monahans parent body regolith, or they may have been introduced from outside.

  17. On the size and structure of helium snowballs formed around charged atoms and clusters of noble gases.

    PubMed

    Bartl, Peter; Leidlmair, Christian; Denifl, Stephan; Scheier, Paul; Echt, Olof

    2014-09-18

    Helium nanodroplets doped with argon, krypton, or xenon are ionized by electrons and analyzed in a mass spectrometer. HenNgx(+) ions containing up to seven noble gas (Ng) atoms and dozens of helium atoms are identified; the high resolution of the mass spectrometer combined with advanced data analysis make it possible to unscramble contributions from isotopologues that have the same nominal mass but different numbers of helium or Ng atoms, such as the magic He20(84)Kr2(+) and the isobaric, nonmagic He41(84)Kr(+). Anomalies in these ion abundances reveal particularly stable ions; several intriguing patterns emerge. Perhaps most astounding are the results for HenAr(+), which show evidence for three distinct, solid-like solvation shells containing 12, 20, and 12 helium atoms. This observation runs counter to the common notion that only the first solvation shell is solid-like but agrees with calculations by Galli et al. for HenNa(+) [J. Phys. Chem. A 2011, 115, 7300] that reveal three shells of icosahedral symmetry. HenArx(+) (2 ? x ? 7) ions appear to be especially stable if they contain a total of n + x = 19 atoms. A sequence of anomalies in the abundance distribution of HenKrx(+) suggests that rings of six helium atoms are inserted into the solvation shell each time a krypton atom is added to the ionic core, from Kr(+) to Kr3(+). Previously reported strong anomalies at He12Kr2(+) and He12Kr3(+) [Kim , J. H.; et al. J. Chem. Phys. 2006, 124, 214301] are attributed to a contamination. Only minor local anomalies appear in the distributions of HenXex(+) (x ? 3). The distributions of HenKr(+) and HenXe(+) show strikingly similar, broad features that are absent from the distribution of HenAr(+); differences are tentatively ascribed to the very different fragmentation dynamics of these ions. PMID:24128371

  18. Adsorption of inert gases including element 118 on noble metal and inert surfaces from ab initio Dirac-Coulomb atomic calculations

    NASA Astrophysics Data System (ADS)

    Pershina, V.; Borschevsky, A.; Eliav, E.; Kaldor, U.

    2008-10-01

    The interaction of the inert gases Rn and element 118 with various surfaces has been studied on the basis of fully relativistic ab initio Dirac-Coulomb CCSD(T) calculations of atomic properties. The calculated polarizability of element 118, 46.3 a.u., is the largest in group 18, the ionization potential is the lowest at 8.91 eV, and the estimated atomic radius is the largest, 4.55 a.u. These extreme values reflect, in addition to the general trends in the Periodic Table, the relativistic expansion and destabilization of the outer valence 7p3/2 orbital. Van der Waals coefficients C3 and adsorption enthalpies ?Hads of Ne through element 118 on noble metals and inert surfaces, such as quartz, ice, Teflon, and graphite, were calculated in a physisorption model using the atomic properties obtained. The C3 coefficients were shown to steadily increase in group 18, while the increase in ?Hads from Ne to Rn does not continue to element 118: The large atomic radius of the latter element is responsible for a decrease in the interaction energy. We therefore predict that experimental distinction between Rn and 118 by adsorption on these types of surfaces will not be feasible. A possible candidate for separating the two elements is charcoal; further study is needed to test this possibility.

  19. Fullerenes and the Nature of Planetary Gases

    NASA Technical Reports Server (NTRS)

    Becker, Luann; Poreda, Robert J.; Nuth, Joe

    2003-01-01

    Over the past several decades, two issues have dominated the discussion of planetary noble gas patterns: 1) the general resemblance of the noble gas abundances in carbonaceous chondrites to those measured in the Earth s atmosphere and; 2) atmospheric inventories of argon and neon that fall off significantly with increasing distance from the Sun. The recognition of the latter has led to the conclusion that the planetary component is not found on planets. In particular, the inability to explain the missing xenon reservoir, once thought to be sequestered in crustal rocks has been extremely troublesome. Some models have focused on various fractionations of solar wind rather than condensation as the process for the evolution of noble gases in the terrestrial planets. However, these models cannot explain the observed gradient of the gases, nor do they account for the similar Ne/Ar ratios and the dissimilar planetary Ar/Kr ratios. More recent studies have focused on hydrodynamic escape to explain the fractionation of gases, like neon, in the atmosphere and the mantle. Escape theory also seems to explain, in part, the isotopically heavy argon on Mars, however, it does not explain the discrepancies observed for the abundances of argon and neon on Venus and the Earth. This has led to the assumption that some combination of solar wind implantation, absorption and escape are needed to explain the nature of planetary noble gases.

  20. Basin scale natural gas source, migration and trapping traced by noble gases and major elements: the Pakistan Indus basin

    NASA Astrophysics Data System (ADS)

    Battani, Anne; Sarda, Philippe; Prinzhofer, Alain

    2000-08-01

    He, Ne and Ar concentrations, He and Ar isotopic ratios, carbon isotopic ratios and chemical compositions of hydrocarbon gases were measured in natural gas samples from gas-producing wells in the Indus basin, Pakistan, where no oil has ever been found. 3He/ 4He ratios are in the range 0.01-0.06 Ra (Ra is the atmospheric value of 1.38×10 -6) indicating the absence of mantle-derived helium despite the Trias extension. 40Ar/ 36Ar ratios range from 296 to 800, consistent with variable additions of radiogenic argon to atmospheric, groundwater-derived argon. Rare gas concentrations show large variations, from 6×10 -5 to 1×10 -3 mol/mol for 4He and from 3×10 -7 to 3×10 -5 mol/mol for 36Ar. In general, 36Ar concentrations are high compared to literature data for natural gas. CO 2 and N 2 concentrations are variable, ranging up to 70 and 20%, respectively. Mantle-derived He is not observed, therefore CO 2 and N 2 are not mantle-derived either. Hydrocarbon gas maturity is high, but accumulation efficiency is small, suggesting that early-produced hydrocarbons, including oil, were lost as well as mantle helium. This is consistent with the generally late, Pliocene, trap formation, and explains the high N 2 concentrations, since N 2 is the final species generated at the end of organic matter maturation. Based on ? 13C data, CO 2 originates from carbonate decomposition. Very elevated 20Ne/ 36Ar ratios are found, reaching a maximum of 1.3 (compared to 0.1-0.2 for air-saturated water and 0.5 for air), and these high values are related to the lowest rare gas concentrations. We suggest that this highly fractionated signature is the trace of the past presence of oil in the basin and appeared in groundwater. We propose a model where oil-water contact is followed by gas-water contact, both with Rayleigh distillation for rare gas abundance ratios, thereby generating the fractionated 20Ne/ 36Ar signature in groundwater first and transferring it to gas later. Assuming the gas-water contact occurred shallower than present reservoir depths, this model explains the generally high 36Ar concentrations and low CH 4/ 36Ar ratios compared to other studies on younger basins. It thus provides a historical perspective on fluid transfer in a sedimentary basin, where a gas accumulation may have been buried to greater depth since formation. Rare gas and major element data point to mixing between two gas pulses produced successively. The very CO 2-N 2-rich gases are terminal products of organic matter maturation which have been trapped after important migration. This gas was followed by a more typical thermogenic gas which mixed with it.

  1. A New Low Energy Heavy Ion Accelerator

    Microsoft Academic Search

    R. Laubert; N. Wotherspoon

    1965-01-01

    A heavy ion accelerator and beam transport system have been designed and constructed for studies of the interaction of radiation with matter. The air-insulated electrostatic accelerator was made to our specifications by Radiation Dynamics, Inc., with a beam energy continuously variable from 2-200 Kev. A modified duoplasmatron ion source provides ions of hydrogen, nitrogen, oxygen and noble gases at beam

  2. Common asteroid break-up events of eucrites, diogenites, and howardites and cosmic-ray production rates for noble gases in achondrites

    Microsoft Academic Search

    O. Eugster; Th. Michel

    1995-01-01

    We determined the cosmic-ray produced noble gas abundances in eight diogenites, four eucrites, and four howardites. Using these and additional noble gas and chemical data from the literature, composition and shielding dependent production rates of achondrites for 3He, 21Ne, 38Ar, 78Kr, 83Kr, and 126Xe were derived based on 81Kr?Kr exposure ages. The cosmogenic ratio 22Ne\\/21Ne is found to be a

  3. Using noble gases measured in spring discharge to trace hydrothermal processes in the Norris Geyser Basin, Yellowstone National Park, U.S.A.

    USGS Publications Warehouse

    Gardner, W.P.; Susong, D.D.; Solomon, D.K.; Heasler, H.P.

    2010-01-01

    Dissolved noble gas concentrations in springs are used to investigate boiling of hydrothermal water and mixing of hydrothermal and shallow cool water in the Norris Geyser Basin area. Noble gas concentrations in water are modeled for single stage and continuous steam removal. Limitations on boiling using noble gas concentrations are then used to estimate the isotopic effect of boiling on hydrothermal water, allowing the isotopic composition of the parent hydrothermal water to be determined from that measured in spring. In neutral chloride springs of the Norris Geyser Basin, steam loss since the last addition of noble gas charged water is less than 30% of the total hydrothermal discharge, which results in an isotopic shift due to boiling of ?? 2.5% ??D. Noble gas concentrations in water rapidly and predictably change in dual phase systems, making them invaluable tracers of gas-liquid interaction in hydrothermal systems. By combining traditional tracers of hydrothermal flow such as deuterium with dissolved noble gas measurements, more complex hydrothermal processes can be interpreted. ?? 2010 Elsevier B.V.

  4. Noble gases, 81Kr-Kr exposure ages and 244Pu-Xe ages of six eucrites, Béréba, Binda, Camel Donga, Juvinas, Millbillillie, and Stannern

    NASA Astrophysics Data System (ADS)

    Miura, Yayoi N.; Nagao, Keisuke; Sugiura, Naoji; Fujitani, Tatsuya; Warren, Paul H.

    1998-07-01

    Noble gases including radioactive 81Kr ( t1/2 = 2.1 × 10 5 yr) have been measured for the cumulate eucrite Binda and five noncumulate eucrites, Béréba, Camel Donga, Juvinas, Millbillillie, and Stannern, some of which have been repeatedly analyzed. Concentrations of 81Kr, which range from 4.2 × 10 -14 to 3.2 × 10 -13 cm 3 STP/g, roughly correlate with abundances of the main target elements, Sr, Y, and Zr. 81Kr-Kr cosmic-ray exposure ages are obtained as 24.5 ± 0.6 Ma, 21.0 ± 1.6 Ma, 36.6 ± 1.4 Ma, 10.6 ± 0.8 Ma, 20.8 ± 0.5 Ma and 35.1 ± 0.7 Ma, for Béréba, Binda, Camel Donga, Juvinas, Millbillillie, and Stannern, respectively. All the measured eucrites have 244Pu-derived fission Xe. On the basis of fission 136Xe concentrations, 244Pu abundances are calculated to range from 0.40 ppb for Binda to 1.08 ppb for Juvinas. Following the method proposed by Shukolyukov and Begemann (1996a), 244Pu-Xe ages relative to the absolute crystallization age of 4.5578 Ga for Angra dos Reis are determined as -46 ± 18 Ma (Béréba), -29 ± 34 Ma (Binda), -51 ± 16 Ma (Camel Donga), -10 ± 23 Ma (Juvinas), +8 ± 24 Ma (fine-grained portion of Millbillillie), -51 ± 21 Ma (coarse-grained portion of Millbillillie), and -124 ± 13 Ma (Stannern), which correspond to absolute ages ranging from 4.434 Ga (Stannern) to 4.566 Ga (fine-grained portion of Millbillillie). Millbillillie is a mixture of materials with different 244Pu-Xe ages. Stannern's unusually young 244Pu-Xe age might reflect a secondary shock disturbance, but otherwise, it tends to confirm a distinctive mode of igneous petrogenesis in comparison to most other eucrites. The 244Pu-Xe ages of the cumulate eucrites obtained so far (Binda, this work; Moore County, Shukolyukov and Begemann, 1996a) do not differ systematically from those of noncumulate eucrites. The four eucrites with the older 244Pu-Xe ages, Béréba, Binda, Juvinas, and the fine-grained portion of Millbillillie, show significant amounts of radiogenic 129Xe, (0.6-2.3) × 10 -12 cm 3 STP/g (after correction for fission 129Xe), which imply earlier retention of radiogenic 129Xe from extinct 129I than other eucrites with young 244Pu-Xe ages.

  5. Atmospheric Ar and Ne trapped in coesite eclogite during Late Miocene (U)HP metamorphism: implications for the recycling of noble gases in subduction zones

    NASA Astrophysics Data System (ADS)

    Baldwin, S.; Das, J. P.

    2013-12-01

    Several isotopic methods, including 40Ar/39Ar dating of phengite, have been used to determine the timing and duration of (U)HP metamorphism. However, in some (U)HP terranes phengite 40Ar/39Ar data , has yielded anomalously old ages interpreted to result from the presence of extraneous Ar (i.e., either inherited or excess Ar). We analyzed Ar and Ne extracted from phengite and omphacite from coesite eclogite in the Papua New Guinea (U)HP terrane to 1) assess the reliability of 40Ar/39Ar phengite ages to record the timing of (U)HP metamorphism in the youngest (U)HP terrane on Earth, and 2) to assess the non-radiogenic trapped Ar and Ne compositions in minerals that crystallized during subduction zone metamorphism. Step heat experiments on irradiated phengite yielded a 40Ar/39Ar weighted mean age of 8.31 +/- 0.32 Ma (2?) corresponding to ~88% 39Ar released. These results are concordant with previously published 238U/206Pb zircon ages, and nearly concordant with a Lu-Hf garnet isochron age, both obtained on the same sample. Results suggest that phengite reliably records the timing of peak (U)HP metamorphism and that excess 40Ar is not present in this coesite eclogite. Step heat experiments on irradiated phengite and pyroxene yielded 38Ar/36Ar above atmospheric values (>0.1885). These higher 38Ar/36Ar ratios from outgassed irradiated samples results from reactor-produced 38ArCl likely due to the presence of Cl-derived from fluid inclusions (i.e., via the nuclear reaction 37Cl(n,?)38Cl(?)38Ar). The high temperature release of 38ArCl may result from smaller fluid inclusions (<1-2 ?m). To further investigate the composition of non-radiogenic trapped Ar and Ne in coesite eclogite, step heat experiments were performed on multiple unirradiated splits of phengite and omphacite. Both minerals yielded atmospheric 38Ar/36Ar, including for high temperature (>1400°C) steps. The abundance of radiogenic 40Ar corresponds to the respective [K] and ~8 Ma age of minerals also suggesting the absence of excess 40Ar in these samples. Omphacite outgassed at high temperature (>1400°C) also yielded atmospheric 20Ne/22Ne. Results indicate that atmospheric Ar and Ne were trapped when minerals crystallized at ~8 Ma during (U)HP metamorphism. The survival of trapped atmospheric Ar and Ne in minerals formed during (U)HP metamorphism supports models that call for recycling of noble gases from the atmosphere back into the mantle at subduction zones.

  6. Noble Gas Temperature Proxy for Climate Change

    EPA Science Inventory

    Noble gases in groundwater appear to offer a practical approach for quantitatively determining past surface air temperatures over recharge areas for any watershed. The noble gas temperature (NGT) proxy should then permit a paleothermometry of a region over time. This terrestria...

  7. Cosmogenic noble gas paleothermometry

    NASA Astrophysics Data System (ADS)

    Tremblay, Marissa M.; Shuster, David L.; Balco, Greg

    2014-08-01

    We present a theoretical basis for reconstructing paleotemperatures from the open-system behavior of cosmogenic noble gases produced in minerals at Earth's surface. Experimentally-determined diffusion kinetics predicts diffusive loss of cosmogenic 3He and 21Ne from common minerals like quartz and feldspars at ambient temperatures; incomplete retention has also been observed empirically in field studies. We show that the theory of simultaneous production and diffusion that applies to radiogenic noble gases in minerals-the basis of thermochronology-can also be applied to cosmogenic noble gases to reconstruct past surface temperatures on Earth. We use published diffusion kinetics and production rates for 3He in quartz and 21Ne in orthoclase to demonstrate the resolving power of cosmogenic noble gas paleothermometry with respect to exposure duration, temperature, and diffusion domain size. Calculations indicate that, when paired with a quantitatively retained cosmogenic nuclide such as 21Ne or 10Be, observations of cosmogenic 3He in quartz can constrain temperatures during surface exposure in polar and high altitude environments. Likewise, 21Ne retention in feldspars is sensitive to temperatures at lower latitudes and elevations, expanding the potential geographic applicability of this technique to most latitudes. As an example, we present paired measurements of 3He and 10Be in quartz from a suite of Antarctic sandstone erratics to test whether the abundances of cosmogenic 3He agree with what is predicted from first principles and laboratory-determined diffusion kinetics. We find that the amounts of cosmogenic 3He present in these samples are consistent with the known mean annual temperature (MAT) for this region of Antarctica between -25 and -30 °C. These results demonstrate the method's ability to record paleotemperatures through geologic time.

  8. New constraints on the release of noble gases during in vacuo crushing and application to scapolite Br-Cl-I and 40Ar/ 39Ar age determinations

    NASA Astrophysics Data System (ADS)

    Kendrick, M. A.; Phillips, D.

    2009-10-01

    The release of irradiation-produced noble gas isotopes ( 38Ar Cl, 80Kr Br, 128Xe I and 39Ar K) during in vacuo crushing scapolite has been investigated and is compared to quartz. Three thousand crushing strokes released ˜98% of fluid inclusion-hosted noble gas from quartz. In comparison, 3000 crushing strokes released only ˜4% of the lattice-hosted 38Ar Cl from a scapolite gem. In vacuo crushing released lattice Ar preferentially relative to lattice Kr or Xe and prolonged crushing released ˜88% of the lattice-hosted noble gas in 96,000 crushing strokes. We suggest fast diffusion pathways generated by crushing are an important noble gas release mechanism and we demonstrate two applications of prolonged in vacuo crushing on irradiated scapolite. Firstly, scapolite molar Br/Cl and I/Cl values are shown to vary over a similar range as crustal fluids. The Cl-rich scapolite gem from Hunza, Pakistan has Br/Cl of 0.5-0.6 × 10 -3 and I/Cl values of 0.3-2 × 10 -6, that are similar to fluids that have dissolved evaporites. In contrast, three out of four skarn-related scapolites from the Canadian Grenville Province have molar Br/Cl values of 1.5-2.4 × 10 -3, and I/Cl values of 11-24 × 10 -6, that are broadly consistent with skarn formation by magmatic fluids. The fourth Grenvillian scapolite, with only 0.02 wt% Cl, has an exceptionally elevated molar Br/Cl value of up to ˜54 × 10 -3 and I/Cl of 284 × 10 -6. It is unclear if these values reflect the composition of fluids formed during metamorphism or preferential incorporation of Br and I in Cl-poor meionitic scapolite. Secondly, the Grenvillian scapolites give plateau ages of between 830 Ma and 400 Ma. The oldest ages post-date regional skarn formation by ˜200 Myr, but are similar to feldspar cooling ages in the Province. The age variation in these samples is attributed to a combination of factors including variable thermal history and the presence of mineral sub-grains in some of the samples. These sub-grains control the release of 39Ar K, 38Ar Cl and 40Ar? during in vacuo crushing as well as the samples 40Ar? retentivity in nature. Scapolite is suggested as a possible analogue for K-feldspar in thermochronologic studies.

  9. Noble gas Records of Early Evolution of the Earth

    NASA Astrophysics Data System (ADS)

    Ozima, M.; Podoesk, F. A.

    2001-12-01

    Comparison between atmospheric noble gases (except for He) and solar (or meteoritic) noble gases clearly suggests that the Earth should have much more Xe than is present in air, and thus that up to about 90 percent of terrestrial Xe is missing from the Earth (1). In this report, we discuss implications of these observations on I-Pu chronology of the Earth and on the origin of terrestrial He3. Whetherill (2) first noted that an estimated I129/I127 ratio (3x10-6) in the proto-Earth was about two orders of magnitude smaller than values commonly observed in meteorites (10-4), and pointed out the possibility that Earth formation postdated meteorites by about 100Ma. Ozima and Podosek (1999) came to a similar conclusion on the basis of I129/I127-Pu244/U238 systematics (1). In this report, we reexamine I-Pu systematics with new data for crustal I content (295 ppb for a bulk crust, (3)). With imposition of an estimated value of 86 percent missing Xe as a constraint on terrestrial Xe inventory, we conclude that the best estimate for a formation age of the Earth is about 28Ma after the initial condensation of the solar nebula (at 4.57Ga). The formation age thus estimated is significantly later than the generally assumed age of meteorites. We also argue from the I-Pu systematics that the missing Xe became missing place about 120Ma after Earth formation. Assuming that the Earth is mostly degassed, the I-Pu formation age of the Earth can be reasonably assumed to represent a whole Earth event. Therefore, we interpret that the I-Pu age of the Earth represents the time when the Earth started to retain noble gases. More specifically, this may correspond to the time when the proto-Earth attained a sufficient size to exert the necessary gravitational force. A giant impact could be another possibility, but it remains to be seen whether or not a giant impact could quantitatively remove heavier noble gases from the Earth. It is interesting to speculate that missing Xe was sequestered in the core during core formation. Core formation time would then be related to the time of the missing Xe event. The above estimated missing Xe age is close to the core formation age suggested from Nb-Zr systematics (4) and from U-Pb systematics (5), but considerably later than that suggested from Hf-W systematics (6). From a comparison of relative elemental abundance of noble gases between the Earth and the solar composition, we show that terrestrial He3 may be totally unrelated to heavier noble gases. This requires independent origin of terrestrial He3 from heavy noble gases. 1.Ozima M. and Podosek F.A. (1999) JGR, 104(BII), 25493. 2.Whetherill G.W. (1975) Ann. Rev. Nuclear Science, 25, 283. 3.Muramatsu Y. and Wedepohl K.H. (1998) Chemical Geology, 147, 201. 4. Jacobsen S.B. and Yin Q.Z. (2001) Lunar Planetary Science, XXXII, 1961.pdf (abstract). 5.Galer S.J.G. and Goldstein S.L. (1995) in Geophysical Monograph 95, 75-98, AGU. 6.Halliday A.N., Lee D.-C. and Jacobsen S.B. (2000) in Origin of the Earth and Moon, 45-62, Univ. Arizona Press.

  10. A determination of air-sea gas exchange and upper ocean biological production from five noble gasses and tritiugenic helium-3

    E-print Network

    Stanley, Rachel H. R

    2007-01-01

    The five noble gases (helium, neon, argon, krypton, and xenon) are biologically and chemically inert, making them ideal oceanographic tracers. Additionally, the noble gases have a wide range of solubilities and molecular ...

  11. Adsorption of inert gases including element 118 on noble metal and inert surfaces from ab initio Dirac-Coulomb atomic calculations

    Microsoft Academic Search

    V. Pershina; A. Borschevsky; E. Eliav; U. Kaldor

    2008-01-01

    The interaction of the inert gases Rn and element 118 with various surfaces has been studied on the basis of fully relativistic ab initio Dirac-Coulomb CCSD(T) calculations of atomic properties. The calculated polarizability of element 118, 46.3 a.u., is the largest in group 18, the ionization potential is the lowest at 8.91 eV, and the estimated atomic radius is the

  12. The Thermochemical Stability of Ionic Noble Gas Compounds.

    ERIC Educational Resources Information Center

    Purser, Gordon H.

    1988-01-01

    Presents calculations that suggest stoichiometric, ionic, and noble gas-metal compounds may be stable. Bases calculations on estimated values of electron affinity, anionic radius for the noble gases and for the Born exponents of resulting crystals. Suggests the desirability of experiments designed to prepare compounds containing anionic,…

  13. Identifying Recharge Location Using Noble Gas Recharge Temperatures, Pajarito Plateau, New Mexico

    Microsoft Academic Search

    A. H. Manning; M. Dale

    2008-01-01

    The solubility of noble gases in water is temperature dependent. Noble gas concentrations in ground water can therefore be used to determine the temperature at the water table at the recharge location (recharge temperature). The Pajarito Plateau in Northern New Mexico is an example of a hydrogeologic setting where noble gas recharge temperatures provide valuable information about recharge location which

  14. Part I. Decrepitation and degassing behaviour of quartz up to 1560 °C: Analysis of noble gases and halogens in complex fluid inclusion assemblages

    NASA Astrophysics Data System (ADS)

    Kendrick, M. A.; Phillips, D.; Miller, J. McL.

    2006-05-01

    Stepped heating and crushing experiments have been used to investigate the noble gas and halogen degassing behaviour of quartz in detail. Samples with diverse character were selected from the Eloise and Osborne, Iron Oxide Copper Gold (IOCG) ore deposits, and the Railway Fault, 13 km south of the Mt Isa Mine, in the Proterozoic Mt Isa Inlier of northeast Australia. Quartz has been shown to have a bimodal degassing profile. The first degassing mode at temperatures of <700 °C is caused by thermally induced mechanical decrepitation of fluid inclusions. Changes in the Br/Cl, I/Cl, Ar/Cl and 40Ar/ 36Ar composition of gas released at different temperatures up to 700 °C can be related to the decrepitation of different types of fluid inclusion observed by microthermometry. These variations with temperature permit deconvolution of the complex fluid inclusion assemblages associated with the IOCG samples; the ultra high salinity, multi solid (MS) and liquid-vapour-daughter (LVD) fluid inclusions, with a predominantly primary origin, decrepitate at higher temperatures than lower salinity liquid-vapour (LV) and monophase (M) fluid inclusions that have a predominantly secondary origin. Three of the IOCG samples have primary MS and LVD fluid inclusions characterized by molar Br/Cl values of between 0.25 × 10 -3 and 0.66 × 10 -3, I/Cl between 0.37 × 10 -6 and 5.0 × 10 -6, 40Ar/ 36Ar values of <1000 and low 36Ar concentrations of 0.7-1.0 × 10 -6 cm 3 cm -3H 2O. These low values are most easily explained by the involvement of halite dissolution water in IOCG genesis. One of the IOCG samples has Br/Cl of 1.3-2.0 × 10 -3 and I/Cl of 10 × 10 -6, similar to juvenile magmatic fluids in Phanerozoic Porphyry Copper Deposits. This sample also has a higher 36Ar concentration of 3.5 × 10 -6 cm 3 cm -3H 2O and a slightly elevated 40Ar/ 36Ar of 2236. Step heating reveals limited and non-systematic variation within the more homogenous population of LV fluid inclusions from the Railway Fault. The samples have mean values of 8.1 × 10 -3 for Br/Cl; 9.4-12 × 10 -6 for I/Cl; <2000 for 40Ar/ 36Ar; and 4.7-4.8 × 10 -6 cm 3 cm -3H 2O for 36Ar concentration. The Br/Cl values are similar to those previously reported for basinal brines present in silicic alteration at the Mt Isa Mine and the additional data can be explained by interaction of such a bittern brine with fine grained sedimentary rocks in the sub-surface. The second mode of quartz degassing occurs between 1200 and 1450 °C and releases a greater volume of gas than the first degassing mode. Several lines of evidence, including microscope observations, indicate that the gas released at high temperature is also from the fluid inclusion reservoir. However, its release may be triggered by a metastable phase transition of quartz (˜1200 °C) and caution is required in interpretation of the fluid compositions obtained at these temperatures. The data provide an improved understanding of fluid inclusion decrepitation behaviour that is different to that obtained in lower temperatures experiments designed by other workers to investigate H-isotope fractionation.

  15. Noble gas diffusion in silicate liquids

    NASA Astrophysics Data System (ADS)

    Amalberti, J.; Burnard, P.; Laporte, D.

    2013-12-01

    Fractionated noble gas relative abundances (Ne/Ar, Kr/Ar and Xe/Ar) and isotopic compositions (40Ar/36Ar, 38Ar/36Ar, 20Ne/22Ne, 21Ne/22Ne) are found in volcanic materials, notably in pumices (1-3). This has generally been interpreted as fractionation resulting from diffusion. However, there is some disagreement as to whether this fractionation occurs during high temperature magmatic processes (3) or due to diffusion of air into solidified pyroclastic deposits (2). We show that differences in relative noble gas diffusivities (e.g. D4He vs D40Ar, where D is the diffusivity) and isotopic diffusivities (e.g. D40Ar vs D36Ar) reduce at high temperatures (Fig). These results predict minimal fractionation of noble gases during magmatic processes. However, it is important to note that these diffusivities were measured in silicate glasses; the relative noble diffusivities in silicate liquids are poorly known. We have developed a new experimental protocol which will to determine the diffusivities of the noble gases and their isotopes in the liquid state. A graphite crucible c. 0.3 mm diameter and c. 20mm deep is filled with powdered glass of the desired composition, heated to 1773 K for 15 minutes and quenched to form a glass cylinder within the crucible. The crucible is then placed in a low pressure (1 bar) controlled atmosphere vertical furnace and heated at high temperatures (1673-1773K) for 2 hours in a pure N2 atmosphere. At this point noble gases (He and Ar) are introduced into the furnace and allowed to diffuse into the cylinder of liquid for durations of between 30 and 90. After quenching, the glass cylinder, preserving its' diffusion profile, is sawed into c. 1mm thick discs which are measured by conventional noble gas mass spectrometry for noble gas abundances (He, Ar) and isotopes (40,38,36Ar). The results will be presented at the conference. References 1 Kaneoka, I. Earth Planet Sci Letts 48, 284-292 (1980). 2 Pinti, D. L., Wada, N. & Matsuda, J. J. Volcan Geotherm Res 88, 279-289 (1999). 3 Ruzie, L. & Moreira, M. J. Volcan Geotherm Res 192, 142-150 (2010). FIGURE: diffusion of 4He, 40Ar, 38Ar, 36Ar in silicate glass. Our experiments show that at high temperature, there is little or no diffusive fractionation of noble gases (abundances or isotopes) in silicate glasses. Therefore diffusive fractionation of noble gas abundances or isotope ratios can only occur at relatively low temperatures (< 1113 K)

  16. Atmospheric noble gas signatures in deep Michigan Basin brines as indicators of a past thermal event

    Microsoft Academic Search

    Lin Ma; Maria Clara Castro; Chris M. Hall

    2009-01-01

    Atmospheric noble gases (e.g., 22Ne, 36Ar, 84Kr, 130Xe) in crustal fluids are only sensitive to subsurface physical processes. In particular, depletion of atmospheric noble gases in groundwater due to boiling and steam separation is indicative of the occurrence of a thermal event and can thus be used to trace the thermal history of stable tectonic regions. We present noble gas

  17. Waste heat recovery from heavy-duty diesel engine exhaust gases by medium temperature ORC system

    Microsoft Academic Search

    MingShan Wei; JinLi Fang; ChaoChen Ma; Syed Noman Danish

    A medium-temperature waste-heat recovery system based on the organic Rankine cycle (ORC) is designed to recover the exhaust\\u000a energy from a heavy-duty diesel engine. Analysis of the 1st law of thermodynamics for an ORC system is performed. This analysis\\u000a contains two parts. The first part is an analysis with undefined heat exchangers to gain an understanding of the ORC and

  18. Optimizing macromolecular tandem mass spectrometry of large non-covalent complexes using heavy collision gases

    NASA Astrophysics Data System (ADS)

    Lorenzen, Kristina; Versluis, Cees; van Duijn, Esther; van den Heuvel, Robert H. H.; Heck, Albert J. R.

    2007-12-01

    We evaluated and optimized conditions for tandem mass spectrometry on macromolecular protein complexes, using a modified Q-ToF instrument varying the gas pressure inside the hexapole collision cell, and studied the influence of using different collision gases, e.g. argon, krypton and xenon. These variations affected ion transmission through the instrument and dissociation efficiency In particular the high mass fragment ions were generated more readily and transmitted more efficiently using the heavier xenon as collision gas. We used the 800 kDa GroEL 14-mer chaperone machinery for these initial studies. Applying the optimized tandem mass spectrometry conditions, i.e. relatively high pressures and xenon as collision gas, we studied in detail the influence the binding of one and two gp5 substrate proteins had on the gas-phase dissociation of the chaperonin complex constructing break-down diagrams. We observed that the binding of substrate polypeptides had a significant effect on the gas-phase stability of the chaperonin complex, with the complex containing one and two substrate molecules being less susceptible towards dissociation than the substrate free GroEL. Interestingly, the GroEL:gp5 and GroEL:(gp5)2 complexes dissociate exclusively via the elimination of GroEL monomeric ions, indicating that both gp5 substrates are likely encapsulated inside the two cavities of, respectively, the cis and trans ring of the GroEL. From all data acquired, we conclude that the heavier xenon is the preferred collision gas for tandem mass spectrometry on very large macromolecular complexes.

  19. High abundances of noble gas and chlorine delivered to the mantle by serpentinite subduction

    NASA Astrophysics Data System (ADS)

    Kendrick, Mark A.; Scambelluri, Marco; Honda, Masahiko; Phillips, David

    2011-11-01

    The Earth's mantle contains non-radiogenic noble gas isotopes that imply transfer of noble gases from the atmosphere into the mantle through subduction. Hydrated serpentinite rocks within subducting oceanic lithosphere are recognized as key carriers of water and chlorine, but the pathways for noble gas subduction have been poorly constrained. Here we analyse the concentration of noble gas isotopes and halogens in rocks from the Ligurian Alps, Italy and the Betic Cordillera, Spain. These rocks and the fluid inclusions trapped within them preserve a record of serpentinite dehydration during progressively deeper stages of subduction. We find that the noble gas and halogen signature of serpentinites reflects that of sea water and sediment pore fluids. The fluids released become progressively depleted in noble gases and chlorine is subducted to greater depths than bromine or iodine. After complete breakdown of the serpentinites at mantle depths of around 70km, the dehydrated rock residues still retain a seawater-derived noble gas signature and significant chlorine. We suggest that these samples are proxies for serpentinite dehydration in cold slabs at mantle depths of 200km or greater. We conclude that atmospheric noble gases are readily incorporated into hydrous minerals formed close to the sea floor, and incompletely removed by subduction zone metamorphism. This implies that noble gases can be subducted to great depths in the Earth's mantle.

  20. Neutron detection by scintillation of noble-gas excimers

    NASA Astrophysics Data System (ADS)

    McComb, Jacob Collin

    Neutron detection is a technique essential to homeland security, nuclear reactor instrumentation, neutron diffraction science, oil-well logging, particle physics and radiation safety. The current shortage of helium-3, the neutron absorber used in most gas-filled proportional counters, has created a strong incentive to develop alternate methods of neutron detection. Excimer-based neutron detection (END) provides an alternative with many attractive properties. Like proportional counters, END relies on the conversion of a neutron into energetic charged particles, through an exothermic capture reaction with a neutron absorbing nucleus (10B, 6Li, 3He). As charged particles from these reactions lose energy in a surrounding gas, they cause electron excitation and ionization. Whereas most gas-filled detectors collect ionized charge to form a signal, END depends on the formation of diatomic noble-gas excimers (Ar*2, Kr*2,Xe* 2) . Upon decaying, excimers emit far-ultraviolet (FUV) photons, which may be collected by a photomultiplier tube or other photon detector. This phenomenon provides a means of neutron detection with a number of advantages over traditional methods. This thesis investigates excimer scintillation yield from the heavy noble gases following the boron-neutron capture reaction in 10B thin-film targets. Additionally, the thesis examines noble-gas excimer lifetimes with relationship to gas type and gas pressure. Experimental data were collected both at the National Institute of Standards and Technology (NIST) Center for Neutron Research, and on a newly developed neutron beamline at the Maryland University Training Reactor. The components of the experiment were calibrated at NIST and the University of Maryland, using FUV synchrotron radiation, neutron imaging, and foil activation techniques, among others. Computer modeling was employed to simulate charged-particle transport and excimer photon emission within the experimental apparatus. The observed excimer scintillation yields from the 10B( n, alpha)7Li reaction are comparable to the yields of many liquid and solid neutron scintillators. Additionally, the observed slow triplet-state decay of neutron-capture-induced excimers may be used in a practical detector to discriminate neutron interactions from gamma-ray interactions. The results of these measurements and simulations will contribute to the development and optimization of a deployable neutron detector based on noble-gas excimer scintillation.

  1. Noble gas magnetic resonator

    DOEpatents

    Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

    2014-04-15

    Precise measurements of a precessional rate of noble gas in a magnetic field is obtained by constraining the time averaged direction of the spins of a stimulating alkali gas to lie in a plane transverse to the magnetic field. In this way, the magnetic field of the alkali gas does not provide a net contribution to the precessional rate of the noble gas.

  2. Noble Gas Proxy Evidence Of Holocene Climate Fluctuations In The Elwha Watershed, Olympic Mountains, Washington

    EPA Science Inventory

    Paleotempertures retrieved from the groundwater archives in the largest watershed (?800 km2) in the Olympic Mountains suggest asynchronous Olympic Peninsula climate responses during the Everson interstade period after the last continental glacial maximum. Dissolved noble gases fr...

  3. Noble gas excimer scintillation following neutron capture in boron thin films

    SciTech Connect

    McComb, Jacob C.; Al-Sheikhly, Mohamad [Nuclear Engineering Program, University of Maryland, College Park, Maryland 20742 (United States); Coplan, Michael A. [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); Thompson, Alan K.; Vest, Robert E. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Clark, Charles W. [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Joint Quantum Institute, National Institute of Standards and Technology and University of Maryland, Gaithersburg, Maryland 20899 (United States)

    2014-04-14

    Far-ultraviolet scintillation signals have been measured in heavy noble gases (argon, krypton, xenon) following boron-neutron capture ({sup 10}B(n,?){sup 7}Li) in {sup 10}B thin films. The observed scintillation yields are comparable to the yields from some liquid and solid neutron scintillators. At noble gas pressures of 107 kPa, the number of photons produced per neutron absorbed following irradiation of a 1200 nm thick {sup 10}B film was 14?000 for xenon, 11?000 for krypton, and 6000 for argon. The absolute scintillation yields from the experimental configuration were calculated using data from (1) experimental irradiations, (2) thin-film characterizations, (3) photomultiplier tube calibrations, and (4) photon collection modeling. Both the boron films and the photomultiplier tube were characterized at the National Institute of Standards and Technology. Monte Carlo modeling of the reaction cell provided estimates of the photon collection efficiency and the transport behavior of {sup 10}B(n,?){sup 7}Li reaction products escaping the thin films. Scintillation yields increased with gas pressure due to increased ionization and excitation densities of the gases from the {sup 10}B(n,?){sup 7}Li reaction products, increased frequency of three-body, excimer-forming collisions, and reduced photon emission volumes (i.e., larger solid angle) at higher pressures. Yields decreased for thicker {sup 10}B thin films due to higher average energy loss of the {sup 10}B(n,?){sup 7}Li reaction products escaping the films. The relative standard uncertainties in the measurements were determined to lie between 14% and 16%. The observed scintillation signal demonstrates that noble gas excimer scintillation is promising for use in practical neutron detectors.

  4. Biomedical Investigations with Laser-Polarized Noble Gas Magnetic Resonance

    NASA Technical Reports Server (NTRS)

    Walsworth, Ronald L.

    2003-01-01

    We pursued advanced technology development of laser-polarized noble gas nuclear magnetic resonance (NMR) as a novel biomedical imaging tool for ground-based and eventually space-based application. This new multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI)-e.g., of lung ventilation-as well as studies of tissue perfusion. In addition, laser-polarized noble gases (3He and 129Xe) do not require a large magnetic field for sensitive detection, opening the door to practical MRI at very low magnetic fields with an open, lightweight, and low-power device. We pursued two technology development specific aims: (1) development of low-field (less than 0.01 T) noble gas MRI of humans; and (2) development of functional MRI of the lung using laser-polarized noble gas and related techniques.

  5. Noble gas dependence of single-bubble sonoluminescence in phosphoric acid

    NASA Astrophysics Data System (ADS)

    Faraji, Mehdi; Moshaii, Ahmad

    2012-09-01

    Single-bubble sonoluminescence (SL) from a concentrated solution of phosphoric acid doped with various noble gases has been studied using a hydrochemical model. The results indicate that in agreement with experiment, the SL temperature increases with the atomic mass of the noble gases. Also, both the temperature and the intensity of SL are remarkably higher for lower partial pressures of a noble gas. Our calculations show that the maximum acquirable SL intensity from phosphoric acid is considerably greater than that of water. This mainly originates from the lower vapor pressure and the higher viscosity of phosphoric acid relative to water making the instability mechanisms completely different for these liquids.

  6. Determination of natural in vivo noble-gas concentrations in human blood.

    PubMed

    Tomonaga, Yama; Brennwald, Matthias S; Livingstone, David M; Tomonaga, Geneviève; Kipfer, Rolf

    2014-01-01

    Although the naturally occurring atmospheric noble gases He, Ne, Ar, Kr, and Xe possess great potential as tracers for studying gas exchange in living beings, no direct analytical technique exists for simultaneously determining the absolute concentrations of these noble gases in body fluids in vivo. In this study, using human blood as an example, the absolute concentrations of all stable atmospheric noble gases were measured simultaneously by combining and adapting two analytical methods recently developed for geochemical research purposes. The partition coefficients determined between blood and air, and between blood plasma and red blood cells, agree with values from the literature. While the noble-gas concentrations in the plasma agree rather well with the expected solubility equilibrium concentrations for air-saturated water, the red blood cells are characterized by a distinct supersaturation pattern, in which the gas excess increases in proportion to the atomic mass of the noble-gas species, indicating adsorption on to the red blood cells. This study shows that the absolute concentrations of noble gases in body fluids can be easily measured using geochemical techniques that rely only on standard materials and equipment, and for which the underlying concepts are already well established in the field of noble-gas geochemistry. PMID:24811123

  7. Determination of Natural In Vivo Noble-Gas Concentrations in Human Blood

    PubMed Central

    Tomonaga, Yama; Brennwald, Matthias S.; Livingstone, David M.; Tomonaga, Geneviève; Kipfer, Rolf

    2014-01-01

    Although the naturally occurring atmospheric noble gases He, Ne, Ar, Kr, and Xe possess great potential as tracers for studying gas exchange in living beings, no direct analytical technique exists for simultaneously determining the absolute concentrations of these noble gases in body fluids in vivo. In this study, using human blood as an example, the absolute concentrations of all stable atmospheric noble gases were measured simultaneously by combining and adapting two analytical methods recently developed for geochemical research purposes. The partition coefficients determined between blood and air, and between blood plasma and red blood cells, agree with values from the literature. While the noble-gas concentrations in the plasma agree rather well with the expected solubility equilibrium concentrations for air-saturated water, the red blood cells are characterized by a distinct supersaturation pattern, in which the gas excess increases in proportion to the atomic mass of the noble-gas species, indicating adsorption on to the red blood cells. This study shows that the absolute concentrations of noble gases in body fluids can be easily measured using geochemical techniques that rely only on standard materials and equipment, and for which the underlying concepts are already well established in the field of noble-gas geochemistry. PMID:24811123

  8. Noble Gas Isotopic Signatures and X-Ray and Electron Diffraction Characteristics of Tagish Lake Carbonaceous Chondrite

    NASA Technical Reports Server (NTRS)

    Nakamura, T.; Noguchi, T.; Zolensky, M. E.; Takaoka, N.

    2001-01-01

    Noble gas isotopic signatures and X-ray and electron diffraction characteristics of Tagish Lake indicate that it is a unique carbonaceous chondrite rich in saponite, Fe-Mg-Ca carbonate, primordial noble gases, and presolar grains. Additional information is contained in the original extended abstract.

  9. The Noble Savage.

    ERIC Educational Resources Information Center

    Greer, Sandy

    1993-01-01

    Traces the history of the "noble savage" concept, from the romantic view of the fifteenth through eighteenth centuries of American Indians as holdovers from the "golden age," to current media images of the medicine man or the Indian princess. Discusses how this patronizing stereotype continues to undermine Indian identity. (SV)

  10. Atmospheric noble gas signatures in deep Michigan Basin brines as indicators of a past thermal event

    NASA Astrophysics Data System (ADS)

    Ma, Lin; Castro, Maria Clara; Hall, Chris M.

    2009-01-01

    Atmospheric noble gases (e.g., 22Ne, 36Ar, 84Kr, 130Xe) in crustal fluids are only sensitive to subsurface physical processes. In particular, depletion of atmospheric noble gases in groundwater due to boiling and steam separation is indicative of the occurrence of a thermal event and can thus be used to trace the thermal history of stable tectonic regions. We present noble gas concentrations of 38 deep brines (~ 0.5-3.6 km) from the Michigan Basin. The atmospheric noble gas component shows a strong depletion pattern with respect to air saturated water. Depletion of lighter gases ( 22Ne and 36Ar) is stronger compared to the heavier ones ( 84Kr and 130Xe). To understand the mechanisms responsible for this overall atmospheric noble gas depletion, phase interaction models were tested. We show that this atmospheric noble gas depletion pattern is best explained by a model involving subsurface boiling and steam separation, and thus, consistent with the occurrence of a past thermal event of mantle origin as previously indicated by both high 4He/heat flux ratios and the presence of primordial mantle He and Ne signatures in the basin. Such a conceptual model is also consistent with the presence of past elevated temperatures in the Michigan Basin (e.g., ~ 80-260 °C) at shallow depths as suggested by previous thermal studies in the basin. We suggest that recent reactivation of the ancient mid-continent rift system underneath the Michigan Basin is likely responsible for the release of both heat and mantle noble gases into the basin via deep-seated faults and fracture zones. Relative enrichment of atmospheric Kr and Xe with respect to Ar is also observed, and is interpreted as reflecting the addition of sedimentary Kr and Xe from associated hydrocarbons, following the hydrothermal event. This study pioneers the use of atmospheric noble gases in subsurface fluids to trace the thermal history of stable tectonic regions.

  11. Biomedical Investigations with Laser-Polarized Noble Gas Magnetic Resonance

    NASA Technical Reports Server (NTRS)

    Walsworth, Ronald L.

    2001-01-01

    We are developing laser-polarized noble gas nuclear magnetic resonance (NMR) as a novel biomedical imaging tool for ground-based and eventually space-based application. This emerging multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI) (e.g., of lung ventilation) as well as studies of tissue perfusion. In addition, laser-polarized noble gases (He-3 and Xe-129) do not require a large magnetic field for sensitive detection, opening the door to practical MRI at very low magnetic fields with an open, lightweight, and low-power device. We are pursuing two specific aims in this research. The first aim is to develop a low-field (< 0.01 T) instrument for noble gas MRI of humans, and the second aim is to develop functional MRI of the lung using laser-polarized Xe-129 and related techniques.

  12. Study of performance characteristics of noble metal thermocouple materials to 2000 C

    NASA Technical Reports Server (NTRS)

    Freeze, P. D.; Thomas, D.; Edelman, S.; Stern, J.

    1972-01-01

    Three performance characteristics of noble metal thermocouples in various environments are discussed. Catalytic effects cause significant errors when noble metal thermocouple materials are exposed to air containing unburned gases in temperature ranges from 25 C to 1500 C. The thermoelectric stability of the iridium 40 rhodium to iridium thermocouple system at 2000 C in an oxidizing medium is described. The effects of large and small temperature gradients on the accuracy and stability of temperature measurements are analyzed.

  13. Perspectives of hyperpolarized noble gas MRI beyond 3He.

    PubMed

    Lilburn, David M L; Pavlovskaya, Galina E; Meersmann, Thomas

    2013-04-01

    Nuclear Magnetic Resonance (NMR) studies with hyperpolarized (hp) noble gases are at an exciting interface between physics, chemistry, materials science and biomedical sciences. This paper intends to provide a brief overview and outlook of magnetic resonance imaging (MRI) with hp noble gases other than hp (3)He. A particular focus are the many intriguing experiments with (129)Xe, some of which have already matured to useful MRI protocols, while others display high potential for future MRI applications. Quite naturally for MRI applications the major usage so far has been for biomedical research but perspectives for engineering and materials science studies are also provided. In addition, the prospects for surface sensitive contrast with hp (83)Kr MRI is discussed. PMID:23290627

  14. Perspectives of hyperpolarized noble gas MRI beyond 3He

    PubMed Central

    Lilburn, David M.L.; Pavlovskaya, Galina E.; Meersmann, Thomas

    2013-01-01

    Nuclear Magnetic Resonance (NMR) studies with hyperpolarized (hp) noble gases are at an exciting interface between physics, chemistry, materials science and biomedical sciences. This paper intends to provide a brief overview and outlook of magnetic resonance imaging (MRI) with hp noble gases other than hp 3He. A particular focus are the many intriguing experiments with 129Xe, some of which have already matured to useful MRI protocols, while others display high potential for future MRI applications. Quite naturally for MRI applications the major usage so far has been for biomedical research but perspectives for engineering and materials science studies are also provided. In addition, the prospects for surface sensitive contrast with hp 83Kr MRI is discussed. PMID:23290627

  15. High temperature, oxidation resistant noble metal-Al alloy thermocouple

    NASA Technical Reports Server (NTRS)

    Smialek, James L. (inventor); Gedwill, Michael G. (inventor)

    1994-01-01

    A thermocouple is disclosed. The thermocouple is comprised of an electropositive leg formed of a noble metal-Al alloy and an electronegative leg electrically joined to form a thermocouple junction. The thermocouple provides for accurate and reproducible measurement of high temperatures (600 - 1300 C) in inert, oxidizing or reducing environments, gases, or vacuum. Furthermore, the thermocouple circumvents the need for expensive, strategic precious metals such as rhodium as a constituent component. Selective oxidation of rhodium is also thereby precluded.

  16. Photoionization of noble-gas atoms by ultrashort electromagnetic pulses

    SciTech Connect

    Astapenko, V. A., E-mail: astval@mail.ru; Svita, S. Yu. [State University, Moscow Institute of Physics and Technology (Russian Federation)

    2014-11-15

    The photoionization of atoms of noble gases (Ar, Kr, and Xe) by ultrashort electromagnetic pulses of a corrected Gaussian shape is studied theoretically. Computations are performed in the context of perturbation theory using a simple expression for the total probability of photoionization of an atom by electromagnetic pulses. The features of this process are revealed and analyzed for various ranges of the parameters of the problem.

  17. New evidence for a magmatic origin of some gases in the Geysers geothermal reservoir

    SciTech Connect

    Truesdell, A.H.; Kennedy, B.M.; Walters, M.A.; D'Amore, F.

    1994-01-20

    The Geysers vapor-dominated geothermal reservoir is known to have a wide range of gas concentrations in steam (<100 to >75,000 ppmw), but the variations in gas compositions and the origin of the gases have been little studied. Low gas concentrations and steam isotopes similar to meteoric waters are found in the SE Geysers, but steam high in gas and HCI from a high temperature reservoir (HTR) in the NW Geysers has been thought to be related to metamorphic or magmatic brine. New analyses of noble gas isotopes show that the highest gas steam from the HTR has high {sup 3}He/{sup 4}He (8.3 Ra), and very low {sup 36}Ar and radiogenic {sup 40}Ar/{sup 4}He, indicating a strong magmatic component and essentially no atmospheric or crustal noble gases. Other samples from the HTR show various amounts of atmospheric dilution of the magmatic gas and lower HCI and total gas contents. The occurrence of steam in the NW Geysers highly enriched in heavy isotopes of oxygen and hydrogen supports the indications of remnant magmatic fluid: The existence of this fluid strongly suggests that the HTR was formed by rapid heating and catastrophic boiling resulting from injection of magma.

  18. Greenhouse Gases

    MedlinePLUS

    ... CFCs CO Additional Information Introduction What are greenhouse gases? Many chemical compounds present in Earth's atmosphere behave ... a greenhouse gas. Carbon Monoxide and other reactive gases Carbon monoxide (CO) is not considered a direct ...

  19. Large atmospheric noble gas excesses in a shallow aquifer in the Michigan Basin as indicators of a past mantle thermal event

    NASA Astrophysics Data System (ADS)

    Warrier, Rohit B.; Castro, M. Clara; Hall, Chris M.; Lohmann, Kyger C.

    2013-08-01

    Significant atmospheric noble gas excesses in aquifer systems have systematically been linked to increased hydrostatic pressure, either due to increased water table levels or due to the development of ice cover. Measured noble gases (Ne, Ar, Kr, and Xe) in the shallow Saginaw aquifer in the Michigan Basin display both moderate (?20-60% Ne excess) and large (?80->120% Ne excess) excesses of atmospheric noble gases with respect to air saturated water for modern recharge conditions. All large atmospheric noble gas excesses are located in the main discharge area of the Michigan Basin, in the Saginaw Lowlands region. Here, through a step-by-step analysis, we first show that large atmospheric noble gas excesses in the Saginaw aquifer do not result from increased hydrostatic pressure but, instead, are the result of vertical transport of atmospheric noble gases that are believed to have escaped from deep Michigan Basin brines following a past thermal event of mantle origin. Subsequently, we show that the atmospheric noble gas pattern of the entire Michigan Basin strata appears to result from two distinct end-members: (a) an end-member represented by the deepest, most depleted brines from which most of the atmospheric noble gases escaped; and (b) an end-member with excess atmospheric noble gas values above those displayed by the Saginaw samples. The latter is unconstrained due to the dilution effect exerted by recharge water. Using a Rayleigh distillation model we further show that the greater enrichment of lighter relative to heavier noble gases in the Saginaw aquifer in the Saginaw Lowlands area is compatible with either diffusion or solubility related mechanisms. These findings reinforce the notion that a past thermal event is indeed responsible for the atmospheric noble gas excesses found in the Saginaw aquifer in the Saginaw Lowlands area. They are also consistent with and reinforce previous findings with respect to the occurrence of a thermal event of mantle origin in the Michigan Basin.

  20. The trapped noble gas component in achondrites

    NASA Astrophysics Data System (ADS)

    Busemann, Henner; Eugster, Otto

    2002-12-01

    The trapped noble gases Ar, Kr and Xe in several achondrites were analysed. We chose separates of the lodranites Lodran and Graves Nunataks 95209 and bulk samples of the Tatahouine diogenite, Pasamonte eucrite, five aubrites and two angrites. Among these, Lodran, Tatahouine, Pasamonte and the aubrite Norton County have been reported to contain U-Xe, a noble gas component assumed to be the most primitive component in the solar system. U-Xe might have been incorporated into the early Earth. We found large concentrations of Xe in several separates of the Lodran lodranite, however, none of the measurements revealed U-Xe composition. The Xe composition of all achondrites can straightforwardly be explained with mixtures of trapped common Xe-Q, absorbed air and various amounts of fissiogenic and cosmogenic Xe. Reanalysis of literature data for Pasamonte, Angra dos Reis and some aubrites is consistent with Xe-Q as the trapped endmember component and contributions of fissiogenic Xe. The presence of Xe-Q in many primitive achondrites is in agreement with the formation of their parent bodies from originally chondritic precursor material. The Ar-Xe elemental composition of Lodran and the aubrites indicate subsolar composition, which is commonly found in E chondrites. This result supports a model of formation of the aubrites from E-chondritic precursor material.

  1. Research of medical gases in Poland

    PubMed Central

    2013-01-01

    Research of medical gases is well established in Poland and has been marked with the foundation of several professional societies. Numerous academic centers including those dealing with hyperbaric and diving medicine conduct studies of medical gases, in vast majority supported with intramural funds. In general, Polish research of medical gases is very much clinical in nature, covering new applications and safety of medical gases in medicine; on the other hand there are several academic centers pursuing preclinical studies, and elaborating basic theories of gas physiology and mathematical modeling of gas exchange. What dominates is research dealing with oxygen and ozone as well as studies of anesthetic gases and their applications. Finally, several research directions involving noble gas, hydrogen and hydrogen sulfide for cell protection, only begin to gain recognition of basic scientists and clinicians. However, further developments require more monetary spending on research and clinical testing as well as formation of new collective bodies for coordinating efforts in this matter. PMID:23916016

  2. Electronegative gases

    SciTech Connect

    Christophorou, L.G.

    1981-01-01

    Recent knowledge on electronegative gases essential for the effective control of the number densities of free electrons in electrically stressed gases is highlighted. This knowledge aided the discovery of new gas dielectrics and the tailoring of gas dielectric mixtures. The role of electron attachment in the choice of unitary gas dielectrics or electronegative components in dielectric gas mixtures, and the role of electron scattering at low energies in the choice of buffer gases for such mixtures is outlined.

  3. Noble gas encapsulation: clathrate hydrates and their HF doped analogues.

    PubMed

    Mondal, Sukanta; Chattaraj, Pratim Kumar

    2014-09-01

    The significance of clathrate hydrates lies in their ability to encapsulate a vast range of inert gases. Although the natural abundance of a few noble gases (Kr and Xe) is poor their hydrates are generally abundant. It has already been reported that HF doping enhances the stability of hydrogen hydrates and methane hydrates, which prompted us to perform a model study on helium, neon and argon hydrates with their HF doped analogues. For this purpose 5(12), 5(12)6(8) and their HF doped analogues are taken as the model clathrate hydrates, which are among the building blocks of sI, sII and sH types of clathrate hydrate crystals. We use the dispersion corrected and gradient corrected hybrid density functional theory for the calculation of thermodynamic parameters as well as conceptual density functional theory based reactivity descriptors. The method of the ab initio molecular dynamics (AIMD) simulation is used through atom centered density matrix propagation (ADMP) techniques to envisage the structural behaviour of different noble gas hydrates on a 500 fs timescale. Electron density analysis is carried out to understand the nature of Ng-OH2, Ng-FH and Ng-Ng interactions. The current results noticeably demonstrate that the noble gas (He, Ne, and Ar) encapsulation ability of 5(12), 5(12)6(8) and their HF doped analogues is thermodynamically favourable. PMID:25047071

  4. New estimates of the production of volatile gases from ablating carbonaceous micrometeoroids at Earth and Mars during an E-belt-type Late Heavy Bombardment

    NASA Astrophysics Data System (ADS)

    Court, Richard W.; Sephton, Mark A.

    2014-11-01

    Heating and ablation of micrometeoroids during atmospheric entry yields volatile gases capable of altering atmospheric chemistry, surface climate and habitability. We have subjected powdered samples of the carbonaceous chondrites Orgueil (CI1), ALH 88045 (CM1), Cold Bokkeveld (CM2), Murchison (CM2) and Mokoia (CV3) to stepped pyrolysis-Fourier transform infrared spectroscopy to simulate the atmospheric entry of micrometeoroids and to quantify the yields of water, carbon dioxide and sulphur dioxide at various temperatures, offering insights into the nature of their source phases. We have incorporated these data into the recently-developed E-Belt model of the Late Heavy Bombardment (LHB) to estimate the production of volatiles from infalling micrometeoroids at Earth and Mars around four billion years ago. At the present day, the 4 (±2) × 1010 g yr-1 of micrometeoroids arriving at Earth yield around 2.5 (±1.3) × 109 g yr-1 of indigenous water, 4.1 (±2.2) × 109 g yr-1 of total water, 1.9 (±1.0) × 109 g yr-1 of carbon dioxide and about 1.1 (±0.6) × 109 g yr-1 of sulphur dioxide, where “indigenous” water exclude water evolved at the initial pyrolysis step of 250 °C. For Mars, the infall of 6.8 × 109 g yr-1 of micrometeoroids yields 3.6 (±1.9) × 108 g yr-1 of indigenous water, 6.4 (±3.4) × 108 g yr-1 of total water, 2.4 (±1.3) × 108 g yr-1 of carbon dioxide and 1.5 (±0.8) × 108 g yr-1 of sulphur dioxide. The LHB is associated with micrometeoroidal infall masses of 1.3 (±0.8) × 1022 g at Earth and 2.3 (±1.3) × 1021 g at Mars. For Earth, this mass is estimated to have produced 8.3 (±4.9) × 1020 g of indigenous water, 1.4 (±0.8) × 1021 g of total water, 6.3 (±3.7) × 1020 g of carbon dioxide and 3.8 (±2.2) × 1020 g of sulphur dioxide, with production rates in the peak 50 Myr of the LHB estimated at 5.1 (±3.1) × 1012 g yr-1 of indigenous water, 8.6 (±5.1) × 1012 g yr-1 of total water, 3.9 (±2.3) × 1012 g yr-1 of carbon dioxide and 2.3 (±1.4) × 1012 g yr-1 of sulphur dioxide. For Mars, total 4.1-3.7 Ga production of 1.3 (±0.8) × 1020 g of indigenous water, 2.2 (±1.3) × 1020 g of total water, 9.3 (±5.5) × 1019 g of carbon dioxide and around 5.8 (±3.4) × 1019 g of sulphur dioxide is estimated, with peak 50 Myr rates of 8.2 (±4.8) × 1011 g yr-1 of indigenous water, 1.4 (±0.8) × 1012 g yr-1 of total water, 5.8 (±3.5) × 1011 g yr-1 of carbon dioxide and 3.6 (±2.1) × 1011 g yr-1 of sulphur dioxide. The errors in these estimates for the present-day rates are dominated by ±50% uncertainty in the LDEF figure of 4 (±2) × 1010 g yr-1 of micrometeoroids while the errors for the ancient rates are dominated by the similarly large uncertainty regarding the mass ratio of micrometeoroids to asteroids. These errors indicate the need for improved understandings of infall rates and better models of solar system evolution. Current models of climate for early Earth and Mars focus on volcanic outgassing for greenhouse gases and aerosols, but pay less attention to extraterrestrial sources. Our data quantify an additional exogenous source of volatiles that augments the endogenous production.

  5. A new approach to the remediation of heavy metal liquid wastes via off-gases produced by Klebsiella pneumoniae M426.

    PubMed

    Essa, A M M; Creamer, N J; Brown, N L; Macaskie, L E

    2006-11-01

    When the off-gas from an aerobic culture of Klebsiella pneumoniae M426 grown in the absence of added heavy metals was passed through a solution of Hg(2+), Cd(2+), Pb(2+), or Cu(2+) a yellow-white (Hg), white (Cd, Pb), or blue (Cu) precipitate was formed. Metal removal from solution was >97% within 2 h at initial concentrations of (as metal): Hg, 8.5; Cd, 12.6; Pb, 7.8; Cu, 9.5 mg/mL. Mercury was removed from solution at pH 2 and in up to 1 M NaCl. Energy dispersive X-ray microanalysis (EDX) of the precipitates showed them to comprise metal, sulfur and carbon in the case of Hg, Cd, and Pb, and, in the case of Cd and Pb, also oxygen. The pH of the solution increased by 1-2 units at an initial pH of 7 and by 4-5 units at an initial pH of 2. In the case of cadmium and lead, the presence of crystalline metal carbonates and hydroxides was confirmed by X-ray powder diffraction (XRD) analysis and additional peaks were seen which could not be assigned to known compounds in the diffraction file database. In the case of copper, hydroxides, and a form of copper sulfate, were found. In the case of mercury the XRD patterns could not be assigned to any known compound, except for HgCl in the solution at the acidic initial pH. The absence of sharp peaks in the pattern for the Hg-precipitate was indicative of poorly crystalline, nanocrystalline or amorphous material. The unknown mercury compound, since it contained non-carbonate carbon, was suggested to be derived from a volatile organothiol in the gases evolved from the culture. Analysis of the culture head gas by GC-MS showed the presence of dimethyldisulfide as a likely precipitant. No sulfur compound was found using XRD analysis in the case of cadmium and lead, although EDX analysis suggested this as a major component and the lack of XRD pattern is evidence for a non-crystalline metal-organothiol. The exact chemistry of the new materials remains to be elucidated but metal precipitation via a biogenic organothiol is a potentially effective approach to the remediation of aggressive metal wastes. PMID:16958139

  6. Evolution of the geothermal fluids at Los Azufres, Mexico, as traced by noble gas isotopes, 18

    E-print Network

    Long, Bernard

    of noble gases, CO2, H2O and Sr were measured in 10 geothermal wells and 8 hot springs, fumaroles and mud is to provide additional information on fluid circulation in the field and surrounding areas (Araró hot springs magmatic 3 He-rich fluids and groundwater currently discharging at Araró hot springs and enriched

  7. Dating native gold by noble gas analyses

    NASA Technical Reports Server (NTRS)

    Niedermann, S.; Eugster, O.; Hofmann, B.; Thalmann, CH.; Reimold, W. U.

    1993-01-01

    Our recent work on He, Ne, and Ar in Alpine gold samples has demonstrated that gold is extremely retentive for He and could thus, in principle, be used for U/Th-He-4 dating. For vein-type gold from Brusson, Northern Italy, we derived a U/Th-He-4 age of 36 Ma, in agreement with the K-Ar formation age of associated muscovites and biotites. However, in placer gold from the Napf area, Central Switzerland, we observed large excesses of both He-4 and radiogenic Ar-40 (Ar-40 sub rad, defined as Ar-40-295.5-Ar-.36). The gas release systematics indicate two distinct noble gas components, one of which is released below about 800 C and the other one at the melting point of gold (1064 C). We now present results of He and Xe measurements in a 1 g placer gold sample from the river Kruempelgraben, as well as He and Ar data for Brusson vein-type gold and for gold from the Lily Gold Mine, South Africa. We calculate reasonable U/Th-He-4 as well as U-Xe ages based on those gases which are released at approximately 800 C. Probably the low-temperature components represent in-situ-produced radiogenic He and fission Xe, whereas the gases evolving when gold melts have been trapped during gold formation. Therefore, only the low-temperature components are relevant for dating purposes.

  8. Production Rates for Noble-Gas Isotopes in Eucrites

    NASA Technical Reports Server (NTRS)

    Reedy, R. C.; Kim, K. J.

    2004-01-01

    To get cosmic-ray exposure ages of meteorites from measured concentrations of cosmic-ray-produced ("cosmogenic") noble-gas isotopes, production rates for those isotopes are needed. The best production rates take into consideration the composition of the meteorite and the "shielding" of the sample (the pre-atmospheric size and shape of the meteoroid and the sample s location in the meteoroid). For ordinary chondrites, there have been many sets of measurements to establish production systematics. The Ne-22/Ne-21 is often used to help to get shielding-dependent production rates. We report here numerical simulations for the production of isotopes of the light noble gases He, Ne, and Ar in both basaltic and cumulate eucrites for several sizes.

  9. NOBLE GAS PRODUCTION FROM MERCURY SPALLATION AT SNS

    SciTech Connect

    DeVore, Joe R [ORNL; Lu, Wei [ORNL; Schwahn, Scott O [ORNL

    2013-01-01

    Calculations for predicting the distribution of the products of spallation reactions between high energy protons and target materials are well developed and are used for design and operational applications in many projects both within DOE and in other arenas. These calculations are based on theory and limited experimental data that verifies rates of production of some spallation products exist. At the Spallation Neutron Source, a helium stream from the mercury target flows through a system to remove radioactivity from this mercury target offgas. The operation of this system offers a window through which the production of noble gases from mercury spallation by protons may be observed. This paper describes studies designed to measure the production rates of twelve noble gas isotopes within the Spallation Neutron Source mercury target.

  10. Modification of the Light Noble Gases From Genesis Aluminum Collectors

    Microsoft Academic Search

    J. C. Mabry; A. M. Meshik; C. M. Hohenberg; D. S. Burnett

    2008-01-01

    The Genesis mission returned samples of solar wind (SW) collected over 2 years at the L1 point for earth- based laboratory measurements. The main goal of the mission is to obtain accurate, high precision isotopic measurements of trace elements in the SW. Since there are several processes and effects that can alter the laboratory measured value from the true SW

  11. Assessment of Noble Gases in the Savannah River Site Environment

    SciTech Connect

    Carlton, W.H.; Murphy, C.E. Jr.

    1995-04-01

    A series of documents has been published that assesses the impact of various radionuclides released to the environment by Savannah River Site operations. The quantity released, the disposition of the radionuclides in the environment, and the dose to offsite individuals has been presented for carbon, cesium, iodine, plutonium, strontium, technetium, tritium, and uranium. An assessment of the impact of non-radioactive mercury also has been published.

  12. Noble gases in diamonds - Occurrences of solarlike helium and neon

    NASA Technical Reports Server (NTRS)

    Honda, M.; Reynolds, J. H.; Roedder, E.; Epstein, S.

    1987-01-01

    Seventeen diamond samples from diverse locations were analyzed for the contents of He, Ar, Kr, and Xe, and of their isotopes, using a Reynolds (1956) type glass mass spectrometer. The results disclosed a large spread in the He-3/He-4 ratios, ranging from values below atmospheric to close to the solar ratio. In particular, solarlike He-3/He-4 ratios were seen for an Australian colorless diamond composite and an Arkansas diamond, which also displayed solarlike neon isotopic ratios. Wide variation was also observed in the He-4/Ar-40 ratios, suggesting a complex history for the source regions and the diamond crystallization processes.

  13. Sequestration of noble gases in giant planet interiors

    E-print Network

    Wilson, Hugh F; 10.1103/PhysRevLett.104.121101

    2010-01-01

    The Galileo probe showed that Jupiter's atmosphere is severely depleted in neon compared to protosolar values. We show, via ab initio simulations of the partitioning of neon between hydrogen and helium phases, that the observed depletion can be explained by the sequestration of neon into helium-rich droplets within the postulated hydrogen-helium immiscibility layer of the planet's interior. We also demonstrate that this mechanism will not affect argon, explaining the observed lack of depletion of this gas. This provides strong indirect evidence for hydrogen-helium immiscibility in Jupiter.

  14. Effect of noble gases on an atmospheric greenhouse /Titan/.

    NASA Technical Reports Server (NTRS)

    Cess, R.; Owen, T.

    1973-01-01

    Several models for the atmosphere of Titan have been investigated, taking into account various combinations of neon and argon. The investigation shows that the addition of large amounts of Ne and/or Ar will substantially reduce the hydrogen abundance required for a given greenhouse effect. The fact that a large amount of neon should be present if the atmosphere is a relic of the solar nebula is an especially attractive feature of the models, because it is hard to justify appropriate abundances of other enhancing agents.

  15. The Chemistry of the Noble Gases, Understanding the Atom Series.

    ERIC Educational Resources Information Center

    Chernick, Cedric L.

    The history of the discovery, isolation, characterization, production and use of argon, krypton, xenon, helium, and radon is followed by an account of early attempts to react them with other elements. The use of the electron shell theory of valence to explain their inertness and the reactions of chemists to the production of xenon compounds is…

  16. Method for the purification of noble gases, nitrogen and hydrogen

    DOEpatents

    Baker, John D. (Blackfoot, ID); Meikrantz, David H. (Idaho Falls, ID); Tuggle, Dale G. (Los Alamos, NM)

    1997-01-01

    A method and apparatus for the purification and collection of hydrogen isotopes in a flowing inert gaseous mixture containing impurities, wherein metal alloy getters having the capability of sorbing non-hydrogen impurities such as oxygen, carbon dioxide, carbon monoxide, methane, ammonia, nitrogen and water vapor are utilized to purify the gaseous mixture of impurities. After purification hydrogen isotopes may be more efficiently collected. A plurality of parallel process lines utilizing metal getter alloys can be used to provide for the continuous purification and collection of the hydrogen isotopes.

  17. Method for the purification of noble gases, nitrogen and hydrogen

    DOEpatents

    Baker, J.D.; Meikrantz, D.H.; Tuggle, D.G.

    1997-09-23

    A method and apparatus are disclosed for the purification and collection of hydrogen isotopes in a flowing inert gaseous mixture containing impurities, wherein metal alloy getters having the capability of sorbing non-hydrogen impurities such as oxygen, carbon dioxide, carbon monoxide, methane, ammonia, nitrogen and water vapor are utilized to purify the gaseous mixture of impurities. After purification hydrogen isotopes may be more efficiently collected. A plurality of parallel process lines utilizing metal getter alloys can be used to provide for the continuous purification and collection of the hydrogen isotopes. 15 figs.

  18. Solar Noble Gas Microdistributions in Murchison and CM Rim Formation

    NASA Astrophysics Data System (ADS)

    Woolum, D. S.; Hohenberg, C. M.; Kehm, K.; Poelstra, K.; Guntalilib, E.

    1995-09-01

    Introduction. Identifiable components of certain carbonaceous chondrites have been interpreted as nebula products. MacPherson et al. [1] described some rims around refractory inclusions in Allende (C3V) as accretionary, and Metzler et al. [2] attributed a nebular origin to fine-grained dust mantles (rims) in CM meteorites. In nebula formation scenarios such as that evoked by Metzler et al., we would expect rim material to be largely devoid of solar-implanted noble gases while the brecciated matrix material would be relatively solar gas-rich. Of particular interest in this study, therefore, is examining the microdistribution of solar noble gases in carbonaceous chondrites to attempt to assess the validity of current models for rim formation. Procedure. A polished thick section of Murchison (CM) (~300 micrometers thick) was prepared without epoxy impregnation since epoxy is not compatible with the high-vacuum, noble gas mass spectrometer. Noble gases were extracted from targeted regions in situ by pulsed-laser excavation and measured by an ion-counting noble gas mass spectrometer [3]. Typical excavation volumes were about 150 micrometers x 150 micrometers x 100 micrometers. Previous Results. Neon isotopic data from these measurements were reported at LPSC XXVI [3]. All data extracted from the section's rim areas plot within the triangle defined by a three component mixture between 'planetary' (Ne-A), solar wind, and spallation. However, as pointed out by R. Wieler, the data could also be interpreted as a three component mixture between Ne-A, spallation and Q-Ne [4]. Current Results and Discussion. Figure 1 plots the noble gas elemental ratios for representative (other rim and matrix data, though in agreement, are not plotted in order to reduce clutter) rim and matrix analyses along with Q, referenced to 36Ar and normalized to solar wind (ilmenite 12001 [5]). As expected, the heavier noble gases are dominated by Q. In fact, the Xe and Kr isotopic data are indistinguishable from Q within error (not plotted). In contrast, the lighter gases are overabundant relative to their Q complement. While this enrichment might be interpreted as a contribution from an A-type planetary component (Ne,He-A), similarity between rims and matrix, as shown in Fig. 1, suggests the presence of solar gas since the matrix is certainly a solar gas carrier for this 'gas-rich' meteorite. An identical solar-enriched signature was measured in the inner as well as outer portion of a single ~300 micrometers thick rim, suggesting that all the material in this rim was similarly exposed. Thus, solar wind irradiation appears to be pervasive in this section of Murchison, present in both matrix and throughout all rims measured in this study. Therefore, modification of the simple one-stage model for nebula accretion of rimmed objects [2] may be required. References: [1] MacPherson G. J. et al. (1985) GCA, 49, 2267-2279. [2] Metzler K. et al., GCA, 56, 2873-2897. [3] Hohenberg C. M. (1980) Rev. Sci. Instrum., 51, 1075-1082. [4] Wieler R. et al. (1992) GCA, 56, 2907-2921. [5] Eberhardt P. et al. (1972) Proc. LSC Conf. 3rd, 1821-1856.

  19. Blood gases

    MedlinePLUS

    Blood gases are a measurement of how much oxygen and carbon dioxide are in your blood. They also determine ... taking a sample of blood from the wrist area. The health care provider will insert a small ...

  20. Multiple atmospheric noble gas components in hydrocarbon reservoirs: a study of the Northwest Shelf, Delaware Basin, SE New Mexico

    NASA Astrophysics Data System (ADS)

    Kennedy, B. M.; Torgersen, T.; van Soest, M. C.

    2002-09-01

    The Northwest Shelf of the Delaware Basin, SE New Mexico is the site of several large and productive oil and gas fields. The most productive reservoirs are located in the late Pennsylvanian Morrow and early Permian Abo formations. Production from the latter more important play is predominately from fluvial Abo red beds of the Pecos Slope Field. The oxidizing conditions implied by the reddish color of the formation require an external hydrocarbon source. To test the existing migration model for the region and constrain the location of potential hydrocarbon sources, we measured the elemental and isotopic composition of noble gases produced along with the hydrocarbons. We found the hydrocarbons to be highly enriched in radiogenic 4He, 40*Ar and nucleogenic 21*Ne [F( 4He) = 44,000-250,000; 40Ar/ 36Ar = 400-3145; 21Ne/ 22Ne = 0.044-0.071]. The greatest enrichments occur in the Pecos Slope gas fields. The hydrocarbons also contain three independent nonradiogenic noble gas components each with an atmospheric isotopic composition. One component is most likely air-saturated water (ASW). The second component is enriched in the heavy noble gases [F( 130Xe) > 8.5] and is derived from the hydrocarbon sources. The third component is enriched in Ne [F( 20Ne) > 0.8] that we believe is degassed from sources within the reservoirs. This component is correlated with but decoupled from the dominant source of radiogenic 4He and 40*Ar. Very high concentrations of 4He (up to ˜1% by volume) in the Pecos slope reservoirs require a source external to the reservoirs, such as the underlying Precambrian basement granites and sedimentary equivalents. Structural buckles cutting through the Pecos field may act as high flux vertical pathways for the radiogenic 4He. If the hydrocarbons in the Pecos slope fields have migrated northward from the deeper Delaware Basin, as suggested by compositional trends, then perhaps the buckles also play an important role in the distribution and filling of the Pecos slope reservoirs.

  1. DFT Energetics of Noble Gas Impurities and Schottky Defects in UO2

    NASA Astrophysics Data System (ADS)

    Thompson, Alexander; Wolverton, Chris

    2009-03-01

    There is a strong need to better understand the mechanisms of nuclear fuel swelling in uranium dioxide (UO2) due to formation of fission product gases. Using density functional theory (DFT+U) calculations, we have explored the energetics of noble gases in UO2, Schottky defects (SD) in UO2, and the interaction between these defects. We find: (i) The noble gas atoms show a strong size dependence of the incorporation energy. (ii) The energetics of the SD in three different geometries shows that the preferred geometry is not simply driven by electrostatic effects. (iii) The energetics of each of the noble gas atoms incorporated in a SD show a strong favorable binding, due to strain relief. (iv) For Ar, Kr, and Xe, the binding energy of a noble gas impurity with the SD is larger than the energy required to form a SD, thereby providing an energetic pathway for the ``spontaneous'' formation of these defects. (v) From our calculations, we have constructed a simple model of the critical number of noble gas atoms required to form a bubble.

  2. Noble gas mass spectrometry with a compressor driven recycling system for improved sensitivity

    NASA Astrophysics Data System (ADS)

    Matsumoto, T.; Matsuda, J.; Ozima, M.; Yatsevich, I.

    2009-12-01

    In noble gas (He, Ne, Ar, Kr and Xe) isotope geo- and cosmochemistry and geochronology, there is an increasing need for better precision and sensitivity of the mass spectrometers. Although the presently available noble gas mass spectrometers detect trace amounts (down to 105 atoms) of noble gas atoms contained in natural samples, isotopic ratios measured at that extremely low level are in many cases not precise enough to resolve specific problems. Also, the instrumental limitation narrows the kinds of rocks suitable for analysis. Thus, in order to expand the analytical capability of noble gases to a wider range of samples with possibly much smaller sizes, it is desirable to have a mass spectrometer with better sensitivity. In order to increase the sensitivity of static-mode noble gas mass spectroscopic analysis, we have developed and tested a gas re-circulation system, which uses a commercially available turbo molecular pump (TMP). During the analysis, the sample gases are directed from the collector end towards the ionization source part of the flight tube. Our preliminary results indicate that the apparent sensitivity of krypton and xenon can be increased by a factor of about 20 and 50, respectively. We also found that the gain factor of helium was somewhat smaller and was approximately 2. Such mass-dependence is quite consistent with the compressibility of TMP which is larger for the heavier molecules.

  3. Noble gas studies on regolith materials from Apollo 14 and 15.

    NASA Technical Reports Server (NTRS)

    Bogard, D. D.; Nyquist, L. E.

    1972-01-01

    Abundances and isotopic compositions of the five stable noble gases, He, Ne, Ar, Kr, and Xe in soils and breccia were determined. The samples investigated included material from a range of depths in a trench and a core tube. Noble gas determinations were performed in a 6-inch all-metal mass spectrometer of high sensitivity. The grain size separates and stepwise heating experimental methods used give results that supplement each other. Calculated concentrations of spallation Xe-126 in many of the fines and gas-rich breccia are presented in a table. Bulk soil samples obtained by Apollo 14 show an inverse correlation of spallation Xe-126 with grain size.

  4. How Robust Is The Noble Gas Paleoclimate Proxy?

    NASA Astrophysics Data System (ADS)

    Sun, T.; Hall, C. M.; Castro, M. C.

    2008-12-01

    Noble gas temperatures (NGTs), which are derived from the air saturated water (ASW) component of noble gas concentrations (Ne, Ar, Kr, Xe) in groundwater, have long held the promise of providing a robust thermometer for use in paleoclimate reconstructions (Stute and Schlosser, 1993). In principle, groundwater noble gas concentrations are a simple function of temperature at the water table at the time of recharge, but, in addition to a temperature dependent ASW component, groundwater also incorporates an extra "excess air" component (Heaton and Vogel, 1981) caused by the partial or total incorporation of disconnected air bubbles trapped below the water table. The ASW component has been used to reveal temperature information and the excess air component has been used to indicate humidity and recharge rate. In order to extract recharge temperature and excess air information from four noble gas concentrations, three major models have been developed: the unfractionated air (UA) model (Stute and Schlosser, 1993) which assumes excess air to be totally dissolved; the continuous equilibration (CE) model (Aeschbach-Hertig et al., 2000), which assumes partial incorporation of excess air that reaches equilibrium with the surrounding groundwater; and the oxygen depletion (OD) model (Hall et al., 2005), which takes into consideration that the combined partial pressure of O2 and CO2 is less in the unsaturated zone than in free air. It has been found that even for the same noble gas data set, choosing different NGT models can yield significantly distinct NGTs and excess air concentrations. What is the real climate information revealed by the four noble gas measurement concentrations and is the climate information derived from the groundwater noble gas robust? To answer these questions, we have systematically tested the three NGT models mentioned above on several published noble gas data sets. Our results confirm the conclusion that absolute NGTs and excess air information are highly model dependent. In many cases, for the same noble gas sample, the CE model produced an NGT close to or slightly higher than the UA model NGT and the OD model systematically yielded even higher NGTs. What's more, in the Marshall aquifer in the Michigan Basin (Hall et al., 2005) and the Carrizo aquifer in Texas (Castro et al., 2007), where the groundwater recharge temperature is available, the recharge NGT (i.e., the NGT derived from the samples in recharge areas) using the OD model is closer to the true recharge temperature than NGTs from the other models. The CE model always generates higher excess air concentrations than the UA and OD models. However, even with the significant inconsistency between each model, the relative changes in NGTs in each paleoclimate record are remarkably similar for all the study sites. The same similarity has also been found among the relative excess air concentration change reconstructed by each model. The consistency in the relative NGT and excess air change record strongly suggests that groundwater noble gases can provide robust climate change information that is independent of model selection. Aeschbach-Hertig et al., 2000, Nature, 405, 1040-1044. Castro et al., 2007, Earth Planet. Sci. Lett., v257, 170-187. Hall et al., 2005, Geophys. Res. Lett., 32, L18404, doi:10.1029/2005GL023582 Heaton and Vogel 1981, J. Hydrol.,50(1-4), 201-216 Stute and Schlosser 1993, Climate Change in Continental Isotopic Recors, Geophys. Monogr. Ser., 78, pp. 89-100.

  5. Atmospheric gases

    NSDL National Science Digital Library

    University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

    2003-01-01

    Which gases make up the atmosphere? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to the gaseous components of the atmosphere. Students explore the main gases of the atmosphere using a pop-up pie chart. Descriptions of the gases and their percentages in the atmosphere are provided. Students read about water vapor in the atmosphere, and an animation shows a simplified process of precipitation. A pop-up window explains the effects of dust on the atmosphere, and a photograph shows how large amounts of dust in the atmosphere create the reds and oranges displayed in sunsets. Finally, ozone is introduced to students as a necessary component of human life on Earth. Copyright 2005 Eisenhower National Clearinghouse

  6. Demonstration of noble gas collection using the cryogenic technique

    SciTech Connect

    Moser, L.V.; Delzer, D.B.

    1988-09-01

    Monitoring devices used for detecting and measuring airborne radioactive noble gases in stack emissions have been limited in their precision and detection capability. Cryogenic sampling is one method used for sampling gamma emitting radioactive gases in stack emissions. A cryogenic air sampler, originally developed at the Oak Ridge National Laboratory (ORNL) and further developed by the Systems Demonstration and Environmental Air Sampling Group (SDEASG) at the Oak Ridge Gaseous Diffusion Plant (ORGDP) is being tested. The cryogenic sampler will be used to study the off-gas from various emission points at ORNL after completion of the preliminary study by SDEASG. Work is currently under way to demonstrate the effectiveness of the sampler and the efficiency of the sampling method. Various tests have been and are being conducted to determine the sample collection techniques which will result in the greatest sample transfer efficiency, sampling precision, and gamma emission counting efficiencies. 4 figs., 2 tabs.

  7. Noble gas isotope measurements for spent nuclear fuel reprocessing. IAEA Task 90/0A211 interim report

    SciTech Connect

    Hudson, G.B.

    1993-02-17

    The nuclear fission of actinides in reactor fuel produces large quantities of Kr and Xe as fission products. Because of the high levels of fission Kr and Xe, sample collection and analysis of noble gases for spent fuel diagnostic measurements is a simple, straight-forward technique. In modern reprocessing plants with continuous dissolvers, it will not be possible to use traditional methods for isolating input batches of fuel. This study investigates the feasibility of using noble gas isotope abundance measurements (isotope correlation techniques - ICT) to solve safeguards requirements. Noble gas measurements might be able to provide an independent analysis of Pu contained within dissolves fuel, on an individual fuel assembly basis. The isotopic composition of Kr and Xe in spent fuel reflects both the composition (isotope abundance ratios) of the fission products and the effects of neutron capture on those fission products. We have reviewed the available literature for noble gas analyses of spent reactor fuel. While references are made to noble gas isotope correlations over the last 20 years, we have found little if any detailed analysis of large data sets. The literature search did find several useful reports. Of these papers, one is particularly useful for evaluating noble gas isotopic compositions. The ``Benchmark-paper`` (1) contains 54 Kr and 56 Xe isotopic composition analyses for 4 different reactors with a variety of fuel enrichment factors. Burnup ranges from 8000 to 37000 MWd/tU. Besides the noble gas measurements, a variety of other measurements are reported (actinides and fission products).

  8. Cryogenic method for measuring nuclides and fission gases

    DOEpatents

    Perdue, P.T.; Haywood, F.F.

    1980-05-02

    A cryogenic method is provided for determining airborne gases and particulates from which gamma rays are emitted. A special dewar counting vessel is filled with the contents of the sampling flask which is immersed in liquid nitrogen. A vertically placed sodium-iodide or germanium-lithium gamma-ray detector is used. The device and method are of particular use in measuring and identifying the radioactive noble gases including emissions from coal-fired power plants, as well as fission gases released or escaping from nuclear power plants.

  9. Greenhouse Gases

    NSDL National Science Digital Library

    This is a lesson where learners engage in a radiating heat activity and an activity that measures temperature in models with and without greenhouse gases. Learners will draw conclusions about the effect of greenhouse gases on temperature and on human life and kinesthetically model the absorbing and re-radiation of heat. The lesson models scientific inquiry using the 5E instructional model and includes teacher notes, prerequisite concepts, common misconceptions, student journal and reading. This is lesson 3 in the Astro-Venture Atmospheric Science Training Unit. The purpose of the unit is to increase students’ awareness of and interest in astrobiology and the many career opportunities that utilize science, math and technology skills. The lessons are designed for educators to use in conjunction with the Astro-Venture multimedia modules.

  10. A mass spectrometric line for tritium analysis of water and noble gas measurements from different water amounts in the range of microlitres and millilitres.

    PubMed

    Papp, Laszlo; Palcsu, Laszlo; Major, Zoltan; Rinyu, Laszlo; Tóth, Istvan

    2012-01-01

    This paper describes the procedure followed for noble gas measurements for litres, millilitres and microlitres of water samples in our laboratory, including sample preparation, mass spectrometric measurement procedure, and the complete calibrations. The preparation line extracts dissolved gases from water samples of volumes of 0.2 ? l to 3 l and it separates them as noble and other chemically active gases. Our compact system handles the following measurements: (i) determination of tritium concentration of environmental water samples by the (3)He ingrowth method; (ii) noble gas measurements from surface water and groundwater; and (iii) noble gas measurements from fluid inclusions of solid geological archives (e.g. speleothems). As a result, the tritium measurements have a detection limit of 0.012 TU, and the expectation value (between 1 and 20 TU) is within 0.2 % of the real concentrations with a standard deviation of 2.4 %. The reproducibility of noble gas measurements for water samples of 20-40 ml allows us to determine solubility temperatures by an uncertainty better than 0.5 °C. Moreover, noble gas measurements for tiny water amounts (in the microlitre range) show that the results of the performed calibration measurements for most noble gas isotopes occur with a deviation of less than 2 %. Theoretically, these precisions for noble gas concentrations obtained from measurements of waters samples of a few microlitres allow us to determine noble gas temperatures by an uncertainty of less than 1 °C. Here, we present the first noble gas measurements of tiny amounts of artificial water samples prepared under laboratory conditions. PMID:22537518

  11. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Noble metal alloy. 872.3060 Section 872.3060... Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification . A noble metal alloy is a device composed primarily of...

  12. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Noble metal alloy. 872.3060 Section 872.3060... Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification . A noble metal alloy is a device composed primarily of...

  13. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Noble metal alloy. 872.3060 Section 872.3060... Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification . A noble metal alloy is a device composed primarily of...

  14. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Noble metal alloy. 872.3060 Section 872.3060... Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification . A noble metal alloy is a device composed primarily of...

  15. The atmospheric inventory of Xenon and noble cases in shales The plastic bag experiment

    NASA Technical Reports Server (NTRS)

    Bernatowicz, T. J.; Podosek, F. A.; Honda, M.; Kramer, F. E.

    1984-01-01

    A novel trapped gas analysis protocol is applied to five shales in which the samples are sealed in air to eliminate the possibility of gas loss in the preanalysis laboratory vacuum exposure of a conventional protocol. The test is aimed at a determination concerning the hypothesis that atmospheric noble gases occur in the same proportion as planetary gases in meteorites, and that the factor-of-23 deficiency of air Xe relative to planetary Xe is made up by Xe stored in shales or other sedimentary rocks. The results obtained do not support the shale hypothesis.

  16. The Native American as Noble Savage.

    ERIC Educational Resources Information Center

    Hirschkind, Lynn

    1983-01-01

    White Americans and Native Americans have accepted and used the idea of the noble savage for many purposes. The noble savage imagery has fostered many misconceptions. Native Americans might reformulate their ethnicities to reckon with the present world and gain a more persuasive voice in politics. (AM)

  17. Structural Measurements from Images of Noble Gas Diffusion

    NASA Astrophysics Data System (ADS)

    Cadman, Robert V.; Kadlecek, Stephen J.; Emami, Kiarash; MacDuffie Woodburn, John; Vahdat, Vahid; Ishii, Masaru; Rizi, Rahim R.

    2009-03-01

    Magnetic resonance imaging of externally polarized noble gases such as ^3He has been used for pulmonary imaging for more than a decade. Because gas diffusion is impeded by the alveoli, the diffusion coefficient of gas in the lung, measured on a time scale of milliseconds, is reduced compared to that of the same gas mixture in the absence of restrictions. When the alveolar walls decay, as in emphysema, diffusivity in the lung increases. In this paper, the relationship between diffusion measurements and the size of the restricting structures will be discussed. The simple case of diffusion in an impermeable cylinder, a structure similar to the upper respiratory airways in mammals, has been studied. A procedure will be presented by which airways of order 2 mm in diameter may be accurately measured; demonstration experiments with plastic tubes will also be presented. The additional developments needed before this technique becomes practical will be briefly discussed.

  18. First-principles study of noble gas impurities and defects in UO{sub 2}

    SciTech Connect

    Thompson, Alexander E.; Wolverton, C. [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States)

    2011-10-01

    We performed a series of density functional theory + U (DFT + U) calculations to explore the energetics of various defects in UO{sub 2}, i.e., noble gases (He, Ne, Ar, Kr, Xe), Schottky defects, and the interaction between these defects. We found the following: (1) collinear antiferromagnetic UO{sub 2} has an energy-lowering distortion of the oxygen sublattice from ideal fluorite positions; (2) DFT + U qualitatively affects the formation volume of Schottky defect clusters in UO{sub 2} (without U the formation volume is negative, but including U the formation volume is positive); (3) the configuration of the Schottky defect cluster is dictated by a competition between electrostatic and surface energy effects; (4) the incorporation energy of inserting noble gas atoms into an interstitial site has a strong dependence on the volume of the noble gas atom, corresponding to the strain it causes in the interstitial site, from He (0.98 eV) to Xe (9.73 eV); (5) the energetics of each of the noble gas atoms incorporated in Schottky defects show strong favorable binding, due to strain relief associated with moving the noble gas atom from the highly strained interstitial position into the vacant space of the Schottky defect; and (6) for argon, krypton, and xenon, the binding energy of a noble gas impurity with the Schottky defect is larger than the formation energy of a Schottky defect, thereby making the formation of Schottky defects thermodynamically favorable in the presence of these large impurities.

  19. Recovery and use of fission product noble metals

    SciTech Connect

    Jensen, G.A.; Rohmann, C.A.; Perrigo, L.D.

    1980-06-01

    Noble metals in fission products are of strategic value. Market prices for noble metals are rising more rapidly than recovery costs. A promising concept has been developed for recovery of noble metals from fission product waste. Although the assessment was made only for the three noble metal fission products (Rh, Pd, Ru), there are other fission products and actinides which have potential value. (DLC)

  20. Solids Liquids and Gases

    NSDL National Science Digital Library

    Ms. Salter

    2009-10-22

    Compare and contrast the three states of matter: solids, liquids and gases. First you will begin by looking at characteristics of each solids, liquids and gasesGases, Liquids and Solids Facts. Then you will look at examples of each stateSolids, Liquids and Gases Video. Demonstrate an understanding of solids, liquids and gases by playing interactive gameSolids, Liquids and Gases Game. Graphic Organizer is here to be filled out as you learn during this lesson. Use the red ...

  1. Incorporation of noble metals into aerogels

    DOEpatents

    Hair, L.M.; Sanner, R.D.; Coronado, P.R.

    1998-12-22

    Aerogels or xerogels containing atomically dispersed noble metals for applications such as environmental remediation are disclosed. New noble metal precursors, such as Pt--Si or Pd(Si--P){sub 2}, have been created to bridge the incompatibility between noble metals and oxygen, followed by their incorporation into the aerogel or xerogel through sol-gel chemistry and processing. Applications include oxidation of hydrocarbons and reduction of nitrogen oxide species, complete oxidation of volatile organic carbon species, oxidative membranes for photocatalysis and partial oxidation for synthetic applications.

  2. Noble Foundation Plant Image Gallery

    NSDL National Science Digital Library

    Provided by the Noble Foundation, a charitable foundation located in Ardmore, Oklahoma that focuses on agriculture and plant biology, this site contains images of over 600 vascular plants native primarily to the Oklahoma-Texas region. Offered as an educational tool for botanists, natural resource managers, and students, the site divides the images into three main categories: Grasses & grasslike plants; Forbs; and Trees, shrubs & woody vines. Within each, users can browse by common name, scientific name, or via a family or tribe index. Entries include a medium-sized image with some close-up thumbnails and information on species, family, longevity, season, origin, height, and flowers. A keyword/ natural language search engine that indexes the entire database is also available. Overall, this is a clean, fast-loading useful resource.

  3. 77 FR 70159 - Marble River, LLC v. Noble Clinton Windpark I, LLC, Noble Ellenburg Windpark, LLC, Noble...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-23

    ...Regulatory Commission [Docket No. EL13-20-000] Marble River, LLC v. Noble Clinton Windpark I, LLC...Commission) Rules of Practice and Procedure, Marble River, LLC (Marble River or Complainant) filed a formal complaint...

  4. A model to explain the various paradoxes associated with mantle noble gas geochemistry

    PubMed Central

    Anderson, Don L.

    1998-01-01

    As a result of an energetic accretion, the Earth is a volatile-poor and strongly differentiated planet. The volatile elements can be accounted for by a late veneer (?1% of total mass of the Earth). The incompatible elements are strongly concentrated into the exosphere (atmosphere, oceans, sediments, and crust) and upper mantle. Recent geochemical models invoke a large primordial undegassed reservoir with chondritic abundances of uranium and helium, which is clearly at odds with mass and energy balance calculations. The basic assumption behind these models is that excess “primordial” 3He is responsible for 3He/4He ratios higher than the average for midocean ridge basalts. The evidence however favors depletion of 3He and excessive depletion of 4He and, therefore, favors a refractory, residual (low U, Th) source Petrological processes such as melt-crystal and melt-gas separation fractionate helium from U and Th and, with time, generate inhomogeneities in the 3He/4He ratio. A self-consistent model for noble gases involves a gas-poor planet with trapping of CO2 and noble gases in the shallow mantle. Such trapped gases are released by later tectonic and magmatic processes. Most of the mantle was depleted and degassed during the accretion process. High 3He/4He gases are viewed as products of ancient gas exsolution stored in low U environments, rather than products of primordial reservoirs. PMID:9689038

  5. Emissions of organic aerosol mass, black carbon, particle number, and regulated and unregulated gases from scooters and light and heavy duty vehicles with different fuels

    NASA Astrophysics Data System (ADS)

    Chirico, R.; Clairotte, M.; Adam, T. W.; Giechaskiel, B.; Heringa, M. F.; Elsasser, M.; Martini, G.; Manfredi, U.; Streibel, T.; Sklorz, M.; Zimmermann, R.; DeCarlo, P. F.; Astorga, C.; Baltensperger, U.; Prevot, A. S. H.

    2014-06-01

    A sampling campaign with seven different types of vehicles was conducted in 2009 at the vehicle test facilities of the Joint Research Centre (JRC) in Ispra (Italy). The vehicles chosen were representative of some categories circulating in Europe and were fueled either with standard gasoline or diesel and some with blends of rapeseed methyl ester biodiesel. The aim of this work was to improve the knowledge about the emission factors of gas phase and particle-associated regulated and unregulated species from vehicle exhaust. Unregulated species such as black carbon (BC), primary organic aerosol (OA) content, particle number (PN), monocyclic and polycyclic aromatic hydrocarbons (PAHs) and a~selection of unregulated gaseous compounds, including nitrous acid (N2O), ammonia (NH3), hydrogen cyanide (HCN), formaldehyde (HCHO), acetaldehyde (CH3CHO), sulfur dioxide (SO2), and methane (CH4), were measured in real time with a suite of instruments including a high-resolution aerosol time-of-flight mass spectrometer, a resonance enhanced multi-photon ionization time-of-flight mass spectrometer, and a high resolution Fourier transform infrared spectrometer. Diesel vehicles, without particle filters, featured the highest values for particle number, followed by gasoline vehicles and scooters. The particles from diesel and gasoline vehicles were mostly made of BC with a low fraction of OA, while the particles from the scooters were mainly composed of OA. Scooters were characterized by super high emissions factors for OA, which were orders of magnitude higher than for the other vehicles. The heavy duty diesel vehicle (HDDV) featured the highest nitrogen oxides (NOx) emissions, while the scooters had the highest emissions for total hydrocarbons and aromatic compounds due to the unburned and partially burned gasoline and lubricant oil mixture. Generally, vehicles fuelled with biodiesel blends showed lower emission factors of OA and total aromatics than those from the standard fuels. The scooters were the main emitters of aromatic compounds, followed by the gasoline vehicle, the diesel vehicles and the HDDV.

  6. CO-oxidation catalysts: Low-temperature CO oxidation over Noble-Metal Reducible Oxide (NMRO) catalysts

    NASA Technical Reports Server (NTRS)

    Herz, Richard K.

    1990-01-01

    Oxidation of CO to CO2 is an important reaction technologically and environmentally and a complex and interesting reaction scientifically. In most cases, the reaction is carried out in order to remove CO as an environmental hazard. A major application of heterogeneous catalysts is catalytic oxidation of CO in the exhaust of combustion devices. The reaction over catalysts in exhaust gas is fast and often mass-transfer-limited since exhaust gases are hot and O2/CO ratios are high. The main challenges to catalyst designers are to control thermal sintering and chemical poisoning of the active materials. The effect of the noble metal on the oxide is discussed, followed by the effect of the oxide on the noble metal, the interaction of the noble metal and oxide to form unique catalytic sites, and the possible ways in which the CO oxidation reaction is catalyzed by the NMRO materials.

  7. Noble gas contents of shergottites and implications for the Martian origin of SNC meteorites

    NASA Technical Reports Server (NTRS)

    Bogard, D. D.; Nyquist, L. E.; Johnson, P.

    1984-01-01

    Three meteorites belonging to the rare group of SNC achondrites, which may have originated in the planet Mars, have been subjected to noble gas isotopic concentration measurements. The elemental and isotopic ratios obtained are unlike those for any other noble gas components except those obtained in analyses of the Martian atmosphere by Viking spacecraft. It is hypothesized that the Kr and Xe gases represent a portion of the Martian atmosphere which was shock-implanted in the case of Elephant Moraine A79001, and that they constitute direct evidence of a Martian origin for the shergottite meteorites. If the SNC meteorites were ejected from Mars at the shergottite shock age of about 180 My ago, they must have been objects more than 6 m in diameter which experienced at least three space collisions to initiate cosmic ray exposure.

  8. Noble gas measurements from tiny water amounts: fluid inclusions in carbonates of speleothemes and coral skeletons

    NASA Astrophysics Data System (ADS)

    Papp, Laszlo; Palcsu, Laszlo; Major, Zoltan

    2010-05-01

    Based on the concentrations of dissolved noble gases in fluid inclusions in speleothems and corals, noble gas temperatures (NGT) might be derived, that would be important climate information [1]. In the case of terrestrial carbonates, it means that the temperature dependency of noble gases in the evolving fluid inclusions is suitable to determine the prevailing temperature. This recognition provides new opportunities for the research of paleoclimate. Additionally, the dissolved noble gases in the fluid inclusions represented in corals could be used to study past sea surface temperatures that are one of the most essential parameter of climate reconstructions. To measure dissolved noble gases in fluid inclusions of a few micro-litres, a noble gas mass spectrometer equipped with an ultra high vacuum preparation line is the most suitable way. The preparation of the carbonate samples is performed in a sample preparation system connected to a static mode VG 5400 noble gas mass spectrometer. As a first step of the sample preparation, one piece of a sample is put into a crusher of the preparation line and then evacuated and heated at night. The crushing of dripstone and coral samples is carried out in a stainless steel pipe with a ferro-magnetic ball at 150 °C temperature, in such a way that the ball is kept on elevating and falling down onto the carbonate sample one hundred times. The aim of the heating is to avoid the water released from the fluid inclusions not to be adsorbed on the surface of the freshly broken carbonate [2]. The water released from the fluid inclusions is frozen into a cold finger, being held at temperature of -70 °C for 15 minutes. In this case, the collection efficiency is better than 99.7 %. Then the cold finger is warmed to 27 °C, and the pressure of the water vapour expanded to the volume of the cold finger is determined by a pressure gauge, which accuracy is better than 0.2 % in the pressure range of 10-2 mbar to 11 mbar. The water vapour pressure range has been calibrated by measuring ten well known water aliquots between 0.45 mg and 3.14 mg sealed in glass capillaries. With this method, the quantity of the water can be determined better than 1% uncertainty. After the dissolved noble gases has been released from the fluid inclusions, they are collected and separated from each other by a cryo system which consists of a stainless steel empty trap and a trap filled with charcoal. The argon, krypton, xenon fraction and the other chemically active gases (N2, O2, CO2, etc.) are trapped in the stainless steel trap at 25 K, while the isotopes of helium and neon in the charcoal trap held at 10 K. So far, the abundance of helium is not measured, because helium does not play a role in the NGT determination due to radiogenic helium component. The helium is pumped away. The neon is released from the stainless steel trap at temperature of 90 K and admitted to the noble gas mass spectrometer. The ion source is tuned for the best sensitivity for neon. The neon isotopes are detected by an electron multiplier in ion counting mode. The argon, krypton and xenon isotopes are measured simultaneously. The gases are released from the stainless steel trap at 150 K, and introduced into a getter trap in order to be purified from the other non-inert gases. Then the pure argon, krypton, xenon fraction is admitted to the mass spectrometer. The isotopes of argon are detected by a Faraday cup, while krypton and xenon isotopes are detected by an electron multiplier. After every single mass spectrometric measurement fast calibration are executed. The calibration of the mass spectrometric measurement is performed by means of well known air aliquots taken from an air reservoir in which the pressure is 2.0052 Pa. The results of the calibration measurements show that the reproducibility is about 2% for all noble gas isotopes measured. This error in noble gas concentrations results in an uncertainty of about 1 °C or lower in the determination of NGT, if the amount of the excess air is smaller than 10 V/V %. To check the overall precis

  9. Noble Gas Analysis for Mars Robotic Missions: Evaluating K-Ar Age Dating for Mars Rock Analogs and Martian Shergottites

    NASA Technical Reports Server (NTRS)

    Park, J.; Ming, D. W.; Garrison, D. H.; Jones, J. H.; Bogard, D. D.; Nagao, K.

    2009-01-01

    The purpose of this noble gas investigation was to evaluate the possibility of measuring noble gases in martian rocks and air by future robotic missions such as the Mars Science Laboratory (MSL). The MSL mission has, as part of its payload, the Sample Analysis at Mars (SAM) instrument, which consists of a pyrolysis oven integrated with a GCMS. The MSL SAM instrument has the capability to measure noble gas compositions of martian rocks and atmosphere. Here we suggest the possibility of K-Ar age dating based on noble gas release of martian rocks by conducting laboratory simulation experiments on terrestrial basalts and martian meteorites. We provide requirements for the SAM instrument to obtain adequate noble gas abundances and compositions within the current SAM instrumental operating conditions, especially, a power limit that prevents heating the furnace above approx.1100 C. In addition, Martian meteorite analyses from NASA-JSC will be used as ground truth to evaluate the feasibility of robotic experiments to constrain the ages of martian surface rocks.

  10. Issues Involving The OSI Concept of Operation For Noble Gas Radionuclide Detection

    SciTech Connect

    Carrigan, C R; Sun, Y

    2011-01-21

    The development of a technically sound protocol for detecting the subsurface release of noble gas radionuclides is critical to the successful operation of an on site inspection (OSI) under the CTBT and has broad ramifications for all aspects of the OSI regime including the setting of specifications for both sampling and analysis equipment used during an OSI. With NA-24 support, we are investigating a variety of issues and concerns that have significant bearing on policy development and technical guidance regarding the detection of noble gases and the creation of a technically justifiable OSI concept of operation. The work at LLNL focuses on optimizing the ability to capture radioactive noble gases subject to the constraints of possible OSI scenarios. This focus results from recognizing the difficulty of detecting gas releases in geologic environments - a lesson we learned previously from the LLNL Non-Proliferation Experiment (NPE). Evaluation of a number of important noble gas detection issues, potentially affecting OSI policy, has awaited the US re-engagement with the OSI technical community. Thus, there have been numerous issues to address during the past 18 months. Most of our evaluations of a sampling or transport issue necessarily involve computer simulations. This is partly due to the lack of OSI-relevant field data, such as that provided by the NPE, and partly a result of the ability of LLNL computer-based models to test a range of geologic and atmospheric scenarios far beyond what could ever be studied in the field making this approach very highly cost effective. We review some highlights of the transport and sampling issues we have investigated during the past year. We complete the discussion of these issues with a description of a preliminary design for subsurface sampling that is intended to be a practical solution to most if not all the challenges addressed here.

  11. Rare gases systematics and mantle structure

    NASA Technical Reports Server (NTRS)

    Allegre, C. J.; Staudacher, T.

    1994-01-01

    The following points are emphasized: one of the most important ones is certainly the first set of experimental data on the solubility of noble gases in metal phases at intermediate pressures, since the core was certainly not formed at ultra high pressures, as emphasized by Ahrens and confirmed by trace elements systematics Wanke. The experimental data clearly show that the core can not be a major reservoir for terrestrial rare gases; the second point is a more elaborate reconsideration of the (40)K-(40)Ar budget of the Earth. This shows that (40)Ar contained in continental crust plus upper mantle plus atmosphere is at maximum half of the (40)Ar inventory of the whole earth. This implies the existence of a two layered mantle; the third point is the discovery by the Australian noble gases group of the existence of high (20)Ne/(22)Ne and low (21)Ne/(22)Ne isotopic ratios in Loihi seamount samples. This results which are different to the MORB ratios confirm the idea of a two layered model, but suggest the existence of a primordial solar type Ne reservoir. Several possibilities about the origin of this (20)Ne excess in the mantle will be discussed; The high (40)Ar/(36)Ar, (129)Xe/(130)Xe and (134) Xe/(130)Xe, (136)Xe/(130)Xe are confirmed by new data. The corresponding ratios for the lower mantle will be discussed. (40)Ar/(36)Ar ratios up to 6000 can be accepted and will not modify the general model of the mantle. They confirm the atmosphere chronology, about 85 percent of the atmosphere was formed in the first 50 My and 15 percent later on.

  12. Optimizing detection of noble gas emission at a former UNE site: sample strategy, collection, and analysis

    NASA Astrophysics Data System (ADS)

    Kirkham, R.; Olsen, K.; Hayes, J. C.; Emer, D. F.

    2013-12-01

    Underground nuclear tests may be first detected by seismic or air samplers operated by the CTBTO (Comprehensive Nuclear-Test-Ban Treaty Organization). After initial detection of a suspicious event, member nations may call for an On-Site Inspection (OSI) that in part, will sample for localized releases of radioactive noble gases and particles. Although much of the commercially available equipment and methods used for surface and subsurface environmental sampling of gases can be used for an OSI scenario, on-site sampling conditions, required sampling volumes and establishment of background concentrations of noble gases require development of specialized methodologies. To facilitate development of sampling equipment and methodologies that address OSI sampling volume and detection objectives, and to collect information required for model development, a field test site was created at a former underground nuclear explosion site located in welded volcanic tuff. A mixture of SF-6, Xe127 and Ar37 was metered into 4400 m3 of air as it was injected into the top region of the UNE cavity. These tracers were expected to move towards the surface primarily in response to barometric pumping or through delayed cavity pressurization (accelerated transport to minimize source decay time). Sampling approaches compared during the field exercise included sampling at the soil surface, inside surface fractures, and at soil vapor extraction points at depths down to 2 m. Effectiveness of various sampling approaches and the results of tracer gas measurements will be presented.

  13. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed...

  14. Noble Metal Nanoparticles for Biosensing Applications

    PubMed Central

    Doria, Gonçalo; Conde, João; Veigas, Bruno; Giestas, Leticia; Almeida, Carina; Assunção, Maria; Rosa, João; Baptista, Pedro V.

    2012-01-01

    In the last decade the use of nanomaterials has been having a great impact in biosensing. In particular, the unique properties of noble metal nanoparticles have allowed for the development of new biosensing platforms with enhanced capabilities in the specific detection of bioanalytes. Noble metal nanoparticles show unique physicochemical properties (such as ease of functionalization via simple chemistry and high surface-to-volume ratios) that allied with their unique spectral and optical properties have prompted the development of a plethora of biosensing platforms. Additionally, they also provide an additional or enhanced layer of application for commonly used techniques, such as fluorescence, infrared and Raman spectroscopy. Herein we review the use of noble metal nanoparticles for biosensing strategies—from synthesis and functionalization to integration in molecular diagnostics platforms, with special focus on those that have made their way into the diagnostics laboratory. PMID:22438731

  15. Results from the XENON10 and the Race to Detect Dark Matter with Noble Liquids

    SciTech Connect

    Shutt, Tom (Case Western Reserve) [Case Western Reserve

    2007-06-13

    Detectors based on liquid noble gases have the potential to revolutionize the direct search for WIMP dark matter. The XENON10 experiment, of which I am a member, has recently announced the results from it's first data run and is now the leading WIMP search experiment. This and other experiments using xenon, argon and neon have the potential to rapidly move from the current kg-scale target mass to the ton scale and well beyond. This should allow a (nearly) definitive test or discovery of dark matter if it is in the form of weakly interacting massive particles.

  16. Method for localized deposition of noble metal catalysts with control of morphology

    DOEpatents

    Ricco, Antonio J. (Albuquerque, NM); Manginell, Ronald P. (Albuquerque, NM); Huber, Robert J. (Bountiful, UT)

    1998-01-01

    A combustible gas sensor that uses a resistively heated, noble metal-coated, micromachined polycrystalline Si filament to calorimetrically detect the presence and concentration of combustible gases. A thin catalytic Pt film was deposited by CVD from the precursor Pt(acac).sub.2 onto microfilaments resistively heated to approximately 500 .degree. C.; Pt deposits only on the hot filament. The filaments tested to date are 2 .mu.m thick .times.10 .mu.m wide .times.100, 250, 500, or 1000 .mu.m-long polycrystalline Si; some are overcoated with a 0.25 .mu.m-thick protective CVD Si.sub.3 N.sub.4 layer.

  17. Apparatus for preparing a solution of a hyperpolarized noble gas for NMR and MRI analysis

    DOEpatents

    Pines, Alexander (Berkeley, CA); Budinger, Thomas (Berkeley, CA); Navon, Gil (Ramat Gan, IL); Song, Yi-Qiao (Berkeley, CA); Appelt, Stephan (Waiblingen, DE); Bifone, Angelo (Rome, IT); Taylor, Rebecca (Berkeley, CA); Goodson, Boyd (Berkeley, CA); Seydoux, Roberto (Berkeley, CA); Room, Toomas (Albany, CA); Pietrass, Tanja (Socorro, NM)

    2008-06-10

    The present invention relates generally to nuclear magnetic resonance (NMR) techniques for both spectroscopy and imaging. More particularly, the present invention relates to methods in which hyperpolarized noble gases (e.g., Xe and He) are used to enhance and improve NMR and MRI. Additionally, the hyperpolarized gas solutions of the invention are useful both in vitro and in vivo to study the dynamics or structure of a system. When used with biological systems, either in vivo or in vitro, it is within the scope of the invention to target the hyperpolarized gas and deliver it to specific regions within the system.

  18. Theory of warm ionized gases: equation of state and kinetic Schottky anomaly.

    PubMed

    Capolupo, A; Giampaolo, S M; Illuminati, F

    2013-10-01

    Based on accurate Lennard-Jones-type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analog in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed. In particular, the predicted plasma electron density in a sonoluminescent bubble turns out to be in good agreement with the value measured in recent experiments. PMID:24229140

  19. Theory of warm ionized gases: Equation of state and kinetic Schottky anomaly

    NASA Astrophysics Data System (ADS)

    Capolupo, A.; Giampaolo, S. M.; Illuminati, F.

    2013-10-01

    Based on accurate Lennard-Jones-type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analog in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed. In particular, the predicted plasma electron density in a sonoluminescent bubble turns out to be in good agreement with the value measured in recent experiments.

  20. Microscopic theory of warm ionized gases: equation of state and kinetic Schottky anomaly

    NASA Astrophysics Data System (ADS)

    Capolupo, A.; Giampaolo, S. M.; Illuminati, F.

    2013-06-01

    Based on accurate Lennard-Jones type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analogue in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed.

  1. Catalytic combustion of actual low and medium heating value gases

    NASA Technical Reports Server (NTRS)

    Bulzan, D. L.

    1982-01-01

    Catalytic combustion of both low and medium heating value gases using actual coal derived gases obtained from operating gasifiers was demonstrated. A fixed bed gasifier with a complete product gas cleanup system was operated in an air blown mode to produce low heating value gas. A fluidized bed gasifier with a water quench product gas cleanup system was operated in both an air enriched and an oxygen blown mode to produce low and medium, heating value gas. Noble metal catalytic reactors were evaluated in 12 cm flow diameter test rigs on both low and medium heating value gases. Combustion efficiencies greater than 99.5% were obtained with all coal derived gaseous fuels. The NOx emissions ranged from 0.2 to 4 g NO2 kg fuel.

  2. Electrical breakdown of gases

    Microsoft Academic Search

    J. M. Meek; J. D. Craggs

    1978-01-01

    A collection of individual works on electrical discharges is presented. Topics covered include: fundamental processes in the electrical breakdown of gases; vacuum breakdown; spark breakdown in uniform fields; corona discharge; spark breakdown in non-uniform fields; breakdown voltage characteristics; irradiation and time lags; high-frequency breakdown of gases; laser-induced electrical breakdown of gases; spark channels; and electrode phenomena. (GHT)

  3. Natural Death and the Noble Savage.

    ERIC Educational Resources Information Center

    Walter, Tony

    1995-01-01

    The belief that dying and grieving are natural processes is widely held in modern bereavement care. Examines four assumption often made in this connection: (1) most primitive cultures deal with death in an accepting way; (2) this way is different than our own; (3) it is a good and noble way; and (4) traditional societies see death as natural. (JBJ)

  4. The Colour of the Noble Metals.

    ERIC Educational Resources Information Center

    Poole, R. T.

    1983-01-01

    Examines the physical basis for colors of noble metals (copper, silver, gold) developed from energy conservation/quantum mechanical view of free electron photoabsorption. Describes production of absorption edges produced by change in density of occupied valence electron states in the d-band, which allows stronger absorption in the visible photon…

  5. Bamboo Pointer belonging to Levi F. Noble

    USGS Multimedia Gallery

    The pointer is a souvenir from the Third Pan-Pacific Science Congress held in Tokyo in 1926. A prominent geologist, Noble (1882-1965) spent his entire career with the U.S. Geological Survey. He began field investigations in 1917, which continued on and off for the next 45 years, where he observed an...

  6. MICROWAVE-ASSISTED SYNTHESIS OF NOBLE NANOSTRUCTURES

    EPA Science Inventory

    Microwave-assisted (MW) spontaneous reduction of noble metal salts, silver (Ag), gold (Au), platinum (Pt) and palladium (Pd) is reported using sugar solutions such as -D glucose, sucrose and maltose, etc. to generate nanomaterials. These MW-assisted reactions, conducted in aqueo...

  7. ALONSO NOBLE Assistant Superintendent, Facilities Management

    E-print Network

    Russell, Lynn

    ALONSO NOBLE Assistant Superintendent, Facilities Management From the very beginning of my career as a groundskeeper. In this role I interacted with irrigation specialists, equipment operators, tree trimmers management assistant superintendent in which I am responsible for landscape maintenance in all Housing

  8. Temporal changes in noble gas compositions within the Aidlinsector ofThe Geysers geothermal system

    SciTech Connect

    Dobson, Patrick; Sonnenthal, Eric; Kennedy, Mack; van Soest,Thijs; Lewicki, Jennifer

    2006-05-03

    The use of nonreactive isotopic tracers coupled to a full thermal-hydrological reservoir simulation allows for an improved method of investigating how reservoir fluids contained within matrix and fractures contribute over time to fluids produced from geothermal systems. A combined field and modeling study has been initiated to evaluate the effects of injection, production, and fracture-matrix interaction on produced noble gas contents and isotopic ratios. Gas samples collected periodically from the Aidlin steam field at The Geysers, California, between 1997 and 2006 have been analyzed for their noble gas compositions, and reveal systematic shifts in abundance and isotopic ratios over time. Because of the low concentrations of helium dissolved in the injection waters, the injectate itself has little impact on the helium isotopic composition of the reservoir fluids over time. However, the injection process may lead to fracturing of reservoir rocks and an increase in diffusion-controlled variations in noble gas compositions, related to gases derived from fluids within the rock matrix.

  9. Rare gas isotopic compositions in natural gases of Japan

    NASA Astrophysics Data System (ADS)

    Nagao, Keisuke; Takaoka, Nobuo; Matsubayashi, Osamu

    1981-04-01

    Isotopic and elemental compositions of rare gases in various types of gas samples collected in the Japanese Islands were investigated. Excess 3He was found in most samples. Many samples showed a regionally uniform high 3He/ 4He ratio of about 7 times the atmospheric ratio. The He concentrations varied from 0.6 to 1800 ppm, and they were low in CO 2-rich gases and high in N 2-rich gases. Ne isotopic deviations from the atmospheric Ne were detected in most volcanic gases. The deviations and the elemental abundance patterns in volcanic gases can be explained by a mixing between two components, one is mass fractionated rare gases and the other is isotopically atmospheric and is enriched in heavy rare gas elements. Ar was a mixture of mass fractionated Ar, atmospheric Ar and radiogenic Ar, and the contribution of radiogenic 40Ar was small in all samples. Except for He, elemental abundance patterns were progressively enriched in the heavier rare gases relative to the atmosphere. Several samples were highly enriched in Kr and Xe relative to the abundance pattern of dissolution equilibrium of atmospheric rare gases in water. The component which is highly enriched in heavy rare gases may be released from sedimentary materials in the crust.

  10. The relativistic polarization propagator for the calculation of electronic excitations in heavy systems

    SciTech Connect

    Pernpointner, Markus, E-mail: Markus.Pernpointner@pci.uni-heidelberg.de [Theoretische Chemie, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)] [Theoretische Chemie, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)

    2014-02-28

    In this work, we present a new four-component implementation of the polarization propagator for accurate calculations of excited states in heavy systems. Differences to existing nonrelativistic realizations are detailed and the energetically lowest final states of the ns{sup 2}np{sup 6} ? ns{sup 2}np{sup 5}(n + 1)s{sup 1} and ns{sup 2}np{sup 6} ? ns{sup 2}np{sup 5}(n + 1)p{sup 1} transitions in noble gases are calculated and compared with experimental data. Already for the light atoms Ne and Ar spin-orbit coupling leads to noticeable zero field splitting that gradually increases in the heavier homologues and eventually invalidates the LS-based description of singlet and triplet excited states. For all four noble gases Ne through Xe, we observe a very good agreement with experimental transition energies in the considered energetic range where the extended version of the propagator implementation in general yields better excitation energy differences than the strict variant. In the extended version, off-diagonal first-order contributions in the two-particle-two-hole block are included that are not present in the strict variant. In case of Kr and Xe, nonrelativistic approaches already exhibit unacceptable deviations in the reproduction of transition energies and the spectral structure. The obtained excited final states are analyzed in terms of atomic contributions to the donor and acceptor orbitals constituting the corresponding wave functions. The relativistic polarization propagator provides a consistent description of electron correlation and relativistic effects especially relevant for the heavier systems where these two contributions are no longer separable.

  11. Ultrapure Gases — From the Production Plant to the Laboratory

    NASA Astrophysics Data System (ADS)

    Simgen, H.; Zuzel, G.

    2007-03-01

    Radioactive noble gas isotopes are a potential source of background in low-level physics experiments, since they are present in the atmosphere and also in widely used gases produced from the atmosphere. We have studied the 39Ar, 85Kr and 222Rn contamination of commercially available nitrogen using low background proportional counters and a rare gas mass spectrometer. It was found that air separation plants are very effective in removing traces of radioactive noble gases and that the available purity can be significantly higher than commercial specifications. On the other hand the gas handling processes which are necessary to deliver gases from the production plant to the customer are a possible source of re-contaminations and determine in most cases the achievable purity. By simulating these processes under realistic conditions we have establish together with the Italian company `SOL group' a well controlled delivery path which can hold the purity. For the short-lived 222Rn the initial contamination is less critical, because it decays away. Instead the emanation rate of the cryogenic tank was found to determine the achievable purity, since it permanently delivers new 222Rn.

  12. Ultrapure Gases - From the Production Plant to the Laboratory

    SciTech Connect

    Simgen, H.; Zuzel, G. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)

    2007-03-28

    Radioactive noble gas isotopes are a potential source of background in low-level physics experiments, since they are present in the atmosphere and also in widely used gases produced from the atmosphere. We have studied the 39Ar, 85Kr and 222Rn contamination of commercially available nitrogen using low background proportional counters and a rare gas mass spectrometer. It was found that air separation plants are very effective in removing traces of radioactive noble gases and that the available purity can be significantly higher than commercial specifications. On the other hand the gas handling processes which are necessary to deliver gases from the production plant to the customer are a possible source of re-contaminations and determine in most cases the achievable purity. By simulating these processes under realistic conditions we have establish together with the Italian company 'SOL group' a well controlled delivery path which can hold the purity. For the short-lived 222Rn the initial contamination is less critical, because it decays away. Instead the emanation rate of the cryogenic tank was found to determine the achievable purity, since it permanently delivers new 222Rn.

  13. Noble gas-derived insights into carbon cycling into the deep biosphere

    NASA Astrophysics Data System (ADS)

    Sherwood Lollar, B.; Ballentine, C. J.; Lippmann-Pipke, J.; Slater, G. F.; Onstott, T. C.; Lin, L.; Moran, J.; Tille, S.; Moser, D. P.; Lacrampe-Couloume, G.

    2009-12-01

    Discovery of chemoautotrophic microbial communities at the mid-ocean ridges launched the exploration of the "deep hot biosphere". Recent advances have demonstrated however that chemoautotrophic communities are not restricted to high temperature hydrothermal settings. The discovery that the terrestrial subsurface too hosts chemoautotrophic ecosystems sustained by the products of water-rock reactions - albeit at lower temperatures and slower rates of reaction - has expanded our view of the extent of the planet that is habitable. Compelling questions remain. What are the ultimate limits to life in the Earth's deep subsurface? What are the underlying controls on microbial metabolic activity and biodiversity? The answers to these questions may provide insight into the evolutionary relationship of deep terrestrial microbial communities to marine sediment-hosted and vent-hosted communities, into the origin of life on Earth, and the potential for life on other planets and moons. At more than 2 km below surface, fracture waters accessed via mines in the tectonically quiescent Precambrian Shields of Canada and South Africa are dominated by radiogenic noble gases and crustal-derived carbon sources. Key uncertainties concerning the deep terrestrial biosphere in these settings include the rates and mechanisms of carbon cycling far from the photosphere, and hence the scale and significance of this remote and exotic reservoir of the global biogeochemical cycle. While carbon geochemistry and stable isotopes, as well as molecular microbiology, have facilitated major advances in identifying the geochemical and microbiological processes involved, this presentation will highlight how coupling these techniques with noble gases constrains the timescales for the deep carbon cycle. In particular, the coupling of noble gas tracers with carbon geochemistry provides the key to recognizing that hydrogeologically isolated fracture networks of geochemically distinct groundwaters exert a major control on the distribution and nature of microbial life and metabolic function in the deep surface. Understanding the nature and distribution of fluids in the subsurface is critical to deciphering the environmental constraints and potential for deep life. Noble gases provide a unique insight into both the sourcing of different components of these fluid-dominated systems and the residence times and timescales of fluid mixing and interaction and hence provide a powerful but to date still underutilized resource for deep biosphere research.

  14. Isotopic studies of rare gases in terrestrial samples and natural nucleosynthesis

    SciTech Connect

    Not Available

    1990-07-01

    This project is concerned with research in rare gas mass spectrometry. We read the natural record that isotopes of the rare gases provide. We study fluids using a system (RARGA) that is sometimes deployed in the field. In 1990 there was a strong effort to reduce the backlog of RARGA samples on hand, so that it was a year of intensive data gathering. Samples from five different areas in the western United States and samples from Guatemala and Australia were analyzed. In a collaborative study we also began analyzing noble gases from rocks associated with the fluids. An important objective, continuing in 1991, is to understand better the reasons for somewhat elevated {sup 3}He/{sup 4}He ratios in regions where there is no contemporary volcanism which could produce the effect by addition of mantle helium. Our helium data have given us and our collaborators some insights, which are to be followed up, into gold mineralization in geothermal regions. Our DOE work in calibrating a sensitive laser microprobe mass spectrometer for noble gases in fluid inclusions continues. Having completed a series of papers on noble gases in diamonds, we next will attempt to make precise isotopic measurements on xenon from mantle sources, in search of evidence for terrestrially elusive {sup 244}Pu decay.

  15. External Photoevaporation of the Solar Nebula: Jupiter's Noble Gas Enrichments

    NASA Astrophysics Data System (ADS)

    Monga, Nikhil; Desch, Steven

    2015-01-01

    We present a model explaining the elemental enrichments in Jupiter's atmosphere, particularly the noble gases Ar, Kr, and Xe. While He, Ne, and O are depleted, seven other elements show similar enrichments (~3 times solar, relative to H). Being volatile, Ar is difficult to fractionate from H2. We argue that external photoevaporation by far-ultraviolet (FUV) radiation from nearby massive stars removed H2, He, and Ne from the solar nebula, but Ar and other species were retained because photoevaporation occurred at large heliocentric distances where temperatures were cold enough (lsim 30 K) to trap them in amorphous water ice. As the solar nebula lost H, it became relatively and uniformly enriched in other species. Our model improves on the similar model of Guillot & Hueso. We recognize that cold temperatures alone do not trap volatiles; continuous water vapor production is also necessary. We demonstrate that FUV fluxes that photoevaporated the disk generated sufficient water vapor in regions <~ 30 K to trap gas-phase species in amorphous water ice in solar proportions. We find more efficient chemical fractionation in the outer disk: whereas the model of Guillot & Hueso predicts a factor of three enrichment when only <2% of the disk mass remains, we find the same enrichments when 30% of the disk mass remains. Finally, we predict the presence of ~0.1 M ? of water vapor in the outer solar nebula and protoplanetary disks in H II regions.

  16. Noble gas impurity balance and exhaust model for DIII-D and JET

    SciTech Connect

    Hillis, D.L.; Hogan, J.; Wade, M.R. [Oak Ridge National Lab., TN (United States); Hellermann, M. von; Ehrenberg, J.; Horton, L.; Koenig, R.; Morgan, P.; Saibene, G. [JET Joint Undertaking, Abingdon (United Kingdom)

    1998-05-01

    Experiments to study the exhaust of noble gases (helium, neon) with cryopumping in DIII-D Advanced Divertor Program (ADP) configuration and in JET (Mk1 configuration) found significant differences in the global exhaust rate of helium, while efficient neon exhaust was observed in both machines. An attempt to better understand the basic processes governing the exhaust of noble gases in ELMy H-mode with cryopumping has been undertaken. Since divertor geometries investigated in the DIII-D and in the JET cases have significant differences, a comparative modeling study has been undertaken using the MIST core impurity transport code and the b2.5 time-independent divertor transport code. Photodiode measurements are used to determine ELM frequency, and charge-exchange recombination (CER) measurements are compared with the MIST ELM model to evaluate transport coefficients in the core plasma. A significant reduction in the anomalous diffusivities is found for the non-ELM component of radial transport without the need for a pinch velocity, and the model provides a more coherent description than the conventional ELM-averaged approach. Sensitivity to boundary conditions has been studied through establishment of a database of divertor enrichment cases using b2.5.

  17. Noble gas isotopes and halogens in volatile-rich inclusions in diamonds

    NASA Technical Reports Server (NTRS)

    Burgess, Raymond; Turner, Grenville

    1994-01-01

    Application of the (40)Ar-(39)Ar method and noble gas studies to diamonds has increased our understanding of their age relationships to the host kimberlite or lamproite, and of the source and composition of volatile-rich fluids in the upper mantle. The properties of diamond (inert, high mechanical strength and low gas diffusivities) means they are especially useful samples for studying gases trapped deep within the earth (less than 150 km) as they are unlikely to have undergone loss or exchange of entrapped material since formation. Volatile-rich fluids (H2O-CO2) are important agents for metasomatic processes in the upper mantle, and the noble gases and halogens preferentially partition into this phase leading to a strong geochemical coherence between these groups of elements. The abundances of the halogens in the major reservoirs of the Earth shows a marked progression from chlorine, concentrated in the oceans, through to iodine which, through its affinity to organic material, is concentrated mainly in sediments. Abundances in the upper mantle are low. This is particularly true for iodine which is of special interest in view of its potential significance as an indicator of sediment recycling and by way of its link to (129)Xe amomalies in the mantle through the low extinct isotope (129)I. Extensions of the (40)Ar-(39)Ar technique enable measurements of halogens and other elements (K, Ca, Ba, U) by production of noble gas isotopes from these species during neutron irradiation. Samples analyzed in this way include 15 coated stones from an unknown source in Zaire, 3 boarts from the Jwaneng and 1 boart from the Orapa kimberlites, both in Botswana.

  18. A new noble gas paleoclimate record in Texas — Basic assumptions revisited

    NASA Astrophysics Data System (ADS)

    Castro, Maria Clara; Hall, Chris Michael; Patriarche, Delphine; Goblet, Patrick; Ellis, Brian Robert

    2007-05-01

    A generally accepted basic principle in relation to the use of the noble gas thermometer in groundwater flow systems is that high-frequency noble gas climatic signals are lost due to the effect of dispersion. This loss of signal, combined with 14C dating issues, makes it only suited to identify major climatic events such as the Last Glacial Maximum (LGM). Consequently, the identification of significant noble gas temperature (NGT) cooling (? 5 °C) with respect to present time has systematically been associated with the occurrence of the LGM even when reasonable water age controls were unavailable. It has also become apparent at a number of studied sites that modern NGTs estimated through standard models [M. Stute, P. Schlosser, Principles and applications of the noble gas paleothermometer, in: P.K. Swart, K.C. Lohmann, J.A. McKenzie, S. Savin, (Eds), Climate change in continental isotopic records, Geophysical monograph 78, AGU (1993) 89-100.; W. Aeschbach-Hertig, F. Peeters, U. Beyerle, R. Kipfer, Paleotemperature reconstruction from noble gases in ground water taking into account equilibration with entrapped air, Nature 405(6790) (2000) 1040-1044.] are unable to reproduce ground temperatures at the interface with the unsaturated zone, a basic requirement for proper paleoclimate reconstruction through noble gases. Instead, a systematic bias to low NGTs in recharge areas is observed. The Carrizo aquifer, in which the LGM was previously identified [M. Stute, P. Schlosser, J.F. Clark, W.S. Broecker, Paleotemperatures in the Southwestern United States derived from noble gases in ground water, Science 256(5059) (1992) 1000-1001.] and which presents an NGT bias of over 4 °C, is an ideal setting to analyze and revise basic principles and assumptions in relation with the use of the noble gas thermometer. Here, we present a new noble gas data set (49 measurements) collected at 20 different locations in the Carrizo aquifer. This new data set together with previously published data (20 measurements) was used to calibrate a 3-D groundwater flow and 4He transport model in which simulations of groundwater age were subsequently carried out. These account for mixing processes due to advection, dispersion, diffusion, and cross-formational flow. We first show that samples previously attributed to the LGM belong in fact to the middle Holocene. Through a step-by-step approach we then proceed to carry out a comparative analysis of both the impact of dispersion on high frequency climatic signals and assumptions underlying competing NGT models. Our combined analysis indicates that groundwater flow systems, at least those with similar characteristics to that of the Carrizo, do have the ability to preserve short term (100-200 yrs) climatic fluctuations archived by noble gases. It also shows that abrupt climate shifts during the mid-late Holocene which are associated with significant NGT changes (? 5 °C) do not reflect equally important changes in the mean annual atmospheric temperature (MAAT). Instead, these reflect the combined effect of atmospheric temperature changes, seasonality of recharge and, above all, significant variations of the water table depth which result from shifts between humid and arid regimes. Together with NGTs, our excess air record plays a critical role in identifying such abrupt climate changes. Specifically, the Carrizo combined data set indicates an abrupt shift from a cool, humid regime to a warmer, arid one at ˜ 1 kyrs BP. A major Holocene (˜ 6 kyrs BP) NGT change of 7.7 °C with respect to present now identified is mostly the result of a dramatic water table drop which occurred during the ˜ 1 kyrs BP transition period. Current NGTs in the Carrizo recharge area do not appear to be recording atmospheric changes. Rather, these are recording ground conditions reflecting mostly the impact of heat flow in the area. We also show that observed systematic offsets in NGT recharge areas can be reconciled through NGT estimation models which account for a noble gas partial pressure increase in the unsaturated zone, poten

  19. Trends in source gases

    NASA Technical Reports Server (NTRS)

    Ehhalt, D. H.; Fraser, P. J.; Albritton, D.; Cicerone, R. J.; Khalil, M. A. K.; Legrand, M.; Makide, Y.; Rowland, F. S.; Steele, L. P.; Zander, R.

    1989-01-01

    Source gases are defined as those gases that, by their breakdown, introduce into the stratosphere halogen, hydrogen, and nitrogen compounds that are important in stratospheric ozone destruction. Given here is an update of the existing concentration time series for chlorocarbons, nitrous oxide, and methane. Also reviewed is information on halogen containing species and the use of these data for establishing trends. Also reviewed is evidence on trends in trace gases that influence tropospheric chemistry and thus the tropospheric lifetimes of source gases, such as carbon dioxide, carbon monoxide, or nitrogen oxides. Much of the information is given in tabular form.

  20. Detection of Noble Gas Radionuclides from an Underground Nuclear Explosion During a CTBT On-Site Inspection

    NASA Astrophysics Data System (ADS)

    Carrigan, Charles R.; Sun, Yunwei

    2014-03-01

    The development of a technically sound approach to detecting the subsurface release of noble gas radionuclides is a critical component of the on-site inspection (OSI) protocol under the Comprehensive Nuclear Test Ban Treaty. In this context, we are investigating a variety of technical challenges that have a significant bearing on policy development and technical guidance regarding the detection of noble gases and the creation of a technically justifiable OSI concept of operation. The work focuses on optimizing the ability to capture radioactive noble gases subject to the constraints of possible OSI scenarios. This focus results from recognizing the difficulty of detecting gas releases in geologic environments—a lesson we learned previously from the non-proliferation experiment (NPE). Most of our evaluations of a sampling or transport issue necessarily involve computer simulations. This is partly due to the lack of OSI-relevant field data, such as that provided by the NPE, and partly a result of the ability of computer-based models to test a range of geologic and atmospheric scenarios far beyond what could ever be studied by field experiments, making this approach very highly cost effective. We review some highlights of the transport and sampling issues we have investigated and complete the discussion of these issues with a description of a preliminary design for subsurface sampling that addresses some of the sampling challenges discussed here.

  1. Screening metal-organic frameworks for selective noble gas adsorption in air: effect of pore size and framework topology.

    PubMed

    Parkes, Marie V; Staiger, Chad L; Perry, John J; Allendorf, Mark D; Greathouse, Jeffery A

    2013-06-21

    The adsorption of noble gases and nitrogen by sixteen metal-organic frameworks (MOFs) was investigated using grand canonical Monte Carlo simulation. The MOFs were chosen to represent a variety of net topologies, pore dimensions, and metal centers. Three commercially available MOFs (HKUST-1, AlMIL-53, and ZIF-8) and PCN-14 were also included for comparison. Experimental adsorption isotherms, obtained from volumetric and gravimetric methods, were used to compare krypton, argon, and nitrogen uptake with the simulation results. Simulated trends in gas adsorption and predicted selectivities among the commercially available MOFs are in good agreement with experiment. In the low pressure regime, the expected trend of increasing adsorption with increasing noble gas polarizabilty is seen. For each noble gas, low pressure adsorption correlates with several MOF properties, including free volume, topology, and metal center. Additionally, a strong correlation exists between the Henry's constant and the isosteric heat of adsorption for all gases and MOFs considered. Finally, we note that the simulated and experimental gas selectivities demonstrated by this small set of MOFs show improved performance compared to similar values reported for zeolites. PMID:23646358

  2. Highly Fluorescent Noble Metal Quantum Dots

    PubMed Central

    Zheng, Jie; Nicovich, Philip R.; Dickson, Robert M.

    2009-01-01

    Highly fluorescent, water-soluble, few-atom noble metal quantum dots have been created that behave as multi-electron artificial atoms with discrete, size-tunable electronic transitions throughout the visible and near IR. These “molecular metals” exhibit highly polarizable transitions and scale in size according to the simple relation, Efermi/N1/3, predicted by the free electron model of metallic behavior. This simple scaling indicates that fluorescence arises from intraband transitions of free electrons and that these conduction electron transitions are the low number limit of the plasmon – the collective dipole oscillations occurring when a continuous density of states is reached. Providing the “missing link” between atomic and nanoparticle behavior in noble metals, these emissive, water-soluble Au nanoclusters open new opportunities for biological labels, energy transfer pairs, and light emitting sources in nanoscale optoelectronics. PMID:17105412

  3. Noble Metals Would Prevent Hydrogen Embrittlement

    NASA Technical Reports Server (NTRS)

    Paton, N. E.; Frandsen, J. D.

    1987-01-01

    According to proposal, addition of small amounts of noble metals makes iron- and nickel-based alloys less susceptible to embrittlement by hydrogen. Metallurgists demonstrated adding 0.6 to 1.0 percent by weight of Pd or Pt eliminates stress/corrosion cracking in type 4130 steel. Proposal based on assumption that similar levels (0.5 to 1.0 weight percent) of same elements effective against hydrogen embrittlement.

  4. Recycling of volatiles at subduction zones: Noble gas evidence from the Tabar-Lihir-Tanga-Feni arc of papua New Guinea

    NASA Technical Reports Server (NTRS)

    Farley, Kenneth; Mcinnes, Brent; Patterson, Desmond

    1994-01-01

    Convergent margin processes play an important but poorly understood role in the distribution of terrestrial volatile species. For example, subduction processes filter volatiles from the subducting package, thereby restricting their return to the mantle. In addition, once extracted from the downgoing slab, volatiles become an essential component in the petrogenesis of island arc magmas. The noble gases, with their systematic variation in physical properties and diversity of radiogenic isotopes, should carry a uniquely valuable record of these processes. However, thus far studies of noble gases in arc volcanics have achieved only limited success in this regard. Subduction-related lavas and geothermal fluids carry (3)He/(4)He ratios equal to or slightly lower than those found in the depleted upper mantle source of mid-ocean ridge basalts. Apparently slab-derived helium (which should have (3)He/(4)He much less than MORB) is extensively diluted by MORB-like helium from the mantle wedge, making it difficult to use helium as a tracer of convergent margin processes. Interpretation of the heavier noble gases (Ne-Ar-Kr-Xe) in arc lavas has also proven difficult, because the lavas carry low noble gas concentrations and hence are subject to pervasive atmospheric contamination. The low noble gas concentrations may be a consequence of degassing in the high level magma chambers characteristic of arc stratovolcanos. We have recently initiated a project to better constrain the behavior of volatiles in subduction zones through geochemical studies of the tectonically unusual volcanoes of the Tabar-Lihir-Tanga-Feni (TLTF) arc in the Bismarck Archipelago, Papua New Guinea.

  5. Noble metallic nanostructures: preparation, properties, applications

    NASA Astrophysics Data System (ADS)

    Atanasov, P. A.; Nedyalkov, N. N.; Dikovska, A. Og; Nikov, Ru; Amoruso, S.; Wang, X.; Bruzzese, R.; Hirano, K.; Shimizu, H.; Terakawa, M.; Obara, M.

    2014-05-01

    The process of formation and the characteristics are studied of noble metal nanostructures created by pulsed laser ablation in vacuum. Femtosecond (fs) and nanosecond (ns) laser systems lasing at different wavelengths are used. Several different modifications of the pulsed lased deposition (PLD) technique, as off-axis deposition and glancing angle deposition configurations are used to create nanostructures. Laser annealing of single or bimetal thin films is used to fabricate alloyed nanostructures. The possibility is demonstrated of tuning the optical properties of gold nanostructures on flexible substrates. Different experimental techniques, as fast photography, optical emission spectroscopy, FE-SEM, AFM, TEM, and Raman spectroscopy are applied to characterize the noble metallic nanostructures produced. The optical spectra of the Au and Ag nanostructures are also studied experimentally and theoretically. The theoretical simulation methods used are: molecular dynamic (MD), finite difference time domain (FDTD) and a method based on the generalized multi-particle Mie (GMM) theory. Applications of noble metal nanostructures to surface enhanced Raman spectroscopy (SERS) and biophotonics are briefly considered.

  6. Transport of Trace Gases

    NASA Technical Reports Server (NTRS)

    Schoeberl, Mark R.

    2005-01-01

    Trace gases measurements are used to diagnose both the chemistry and transport of the atmosphere. These lectures emphasize the interpretation of trace gases measurements and techniques used to untangle chemistry and transport effects. I will discuss PV transform, trajectory techniques, and age-of-air as far as the circulation of the stratosphere.

  7. Biomass - Investigating Gases

    NSDL National Science Digital Library

    Eric Eric Benson

    In this lab activity students generate their own biomass gases by heating wood pellets or wood splints in a test tube. They collect the resulting gases and use the gas to roast a marshmallow. Students also evaluate which biomass fuel is the best by their own criteria or by examining the volume of gas produced by each type of fuel.

  8. ANALYSIS OF PROTOCOL GASES

    EPA Science Inventory

    In 1992, EPA's Atmospheric Research and Exposure Assessment Laboratory initiated a nationwide QA program on the suppliers of EPA Protocol Gases. he program has three goals: to increase the acceptance and use of Protocol Gases by the air monitoring community, to provide a QA check...

  9. Nitrogen and Carbon Isotopes in Presolar Diamond Samples with Known Noble Gas Isotope Signature

    NASA Astrophysics Data System (ADS)

    Verchovsky, A. B.; Huss, G. R.; Pillinger, C. T.

    1994-07-01

    Since the first analyses of C and N isotopes in presolar diamonds with known noble gas isotope composition more than a decade ago [1,2] the investigation of these isotope systems in the diamonds were developed practicallly independently. During this time many interesting details in isotopic systematics of all the elements involved were found and reviewed [3-5]. The main conclusion now reached from a decade of investigation is that presolar diamonds from different meteorites are not identical but appear to consist of several populations [6-8]. Therefore a variety of circumstellar conditions may be involved through a type II supernova model is a good start point in trying to understand diamond synthesis [9]. The evidences from experimental data for all the isotope systems however are still not entirely consistent in the sense that we actually do not know how many carriers the diamonds represent and how the various noble gas carriers are related to those for nitrogen. The finding of a consensus between noble gas and light element analyses would seem to be a vital step so that more detailed nucleosynthesis models may be developed tor the diamond formation. A first point is to answer the question whether HL noble gases and light nitrogen must have been formed at the same astrophysical site. Another important achievement in terms of presolar diamond investigations during the last decade is the purity and number of samples now available. However a well known difficulty is that C, N, and noble gases are never measured all together on the same sample. The purpose of collaboration initiated in this paper is to exploit the availability of good quality samples and to go some way towards overcoming the difficulties of measurement technique incompatibility. We have analyzed three pure diamond samples separated at CalTech from Allende, Orgueil, (henceforth CT samples) and Leoville for N and C isotopic composition by stepped pyrolysis and combustion. The samples preparation and the noble gas results are described in detail elsewhere [7]. It should be noted that sample purity is supposed to be an important condition affecting release pattern of noble gases and N due to chemical reaction between coexisting minerals (for further discussion see [10]. Therefore we expected the influence of the reactions to be eliminated or significantly reduced for the samples studied here compared to those (OU samples) analyzed [6,8] before. Surprisingly we did not find any particular difference in C and N isotope systematics for the CT and OU samples. In particular they have the same carbon and N release profiles and isotope systematics (Figs. 1,2) although OU samples were measured without any attempt to remove spinel, SiC, or other oxidizing acid resistant phases. At low temperature pyrolysis steps, the CT samples have a similar peak of C, which we have previously correlated with P3 noble gases [11]. More important, release temperature of the light nitrogen from the CT samples (Fig. 2) is now confirmed to be significantly lower than that for HL noble gases supporting the hypothesis [11,12] of different carriers for the components or an entirely different release mechanism. Perhaps the most surprising outcome of our investigation was that none of the CT samples measured appeared to be 100% carbon; the reason for this apparent discrepancy ;the at present not clear. References: [1] Swart P. K. et al. (1983) Science, 220, 406-410. [2] Lewis R. S. et a1. (1983) Nature, 305, 767-771. [3] Pillinger C. T. (1993) Phil. Trans. Roy. Soc. Lond. A, 343, 73-76. [4] Anders E. and Zinner E. (1993) Meteoritics, 28, 490-514. [5] Ott U. (1993) Nature, 364, 25-33. [6] Russell S. S. et al. (1991) Science, 254, 1188-1191. [7] Huss G. R. and Lewis R. S. (1994) Meteoritics, in press. [8] Verchovsky A. B. et al. (1993) LPS XXV, 1435-1436. [9] Clayton D. D. et al. (1994) Astrophysics J., in press. [10] Verchovsky A. B. et al. (1994) Meteoritics, this volume. [11] Verchovsky A. B. et al. (1993) Meteoritics, 28, 52-53. [12] Verchovsky A. B. et a1. (1993) LPS XXIV, 1461-1462. Fig. 1

  10. Inert electrode containing metal oxides, copper and noble metal

    DOEpatents

    Ray, Siba P. (Murrysville, PA); Woods, Robert W. (New Kensington, PA); Dawless, Robert K. (Monroeville, PA); Hosler, Robert B. (Sarver, PA)

    2001-01-01

    A cermet composite material is made by treating at an elevated temperature a mixture comprising a compound of iron and a compound of at least one other metal, together with an alloy or mixture of copper and a noble metal. The alloy or mixture preferably comprises particles having an interior portion containing more copper than noble metal and an exterior portion containing more noble metal than copper. The noble metal is preferably silver. The cermet composite material preferably includes alloy phase portions and a ceramic phase portion. At least part of the ceramic phase portion preferably has a spinel structure.

  11. Inert electrode containing metal oxides, copper and noble metal

    DOEpatents

    Ray, Siba P. (Murrysville, PA); Woods, Robert W. (New Kensington, PA); Dawless, Robert K. (Monroeville, PA); Hosler, Robert B. (Sarver, PA)

    2000-01-01

    A cermet composite material is made by treating at an elevated temperature a mixture comprising a compound of iron and a compound of at least one other metal, together with an alloy or mixture of copper and a noble metal. The alloy or mixture preferably comprises particles having an interior portion containing more copper than noble metal and an exterior portion containing more noble metal than copper. The noble metal is preferably silver. The cermet composite material preferably includes alloy phase portions and a ceramic phase portion. At least part of the ceramic phase portion preferably has a spinel structure.

  12. Mantle and crustal sources of carbon, nitrogen, and noble gases in Cascade-Range and Aleutian-Arc volcanic gases

    Microsoft Academic Search

    Robert B. Symonds; Robert J. Poreda; William C. Evans; Cathy J. Janik; Beatrice E. Ritchie

    ABSTRACT Here we report anhydrous chemical (CO2, H2S, N2, H2, CH4, O2, Ar, He, Ne) and isotopic (, N) compositions of virtually air- free gas samples collected between 1994 and 1998 from 12 quiescent but potentially restless volcanoes in the Cascade Range and Aleutian Arc (CRAA). Sample sites include ?173°C fumaroles and springs at Mount Shasta, Mount Hood, Mount St.

  13. Evaluation of argon ages and integrity of fluid-inclusion compositions: stepwise noble gas heating experiments on 1.87 Ga alunite from Tapajós Province, Brazil

    Microsoft Academic Search

    G. P. Landis; L. W. Snee; C. Juliani

    2005-01-01

    Quantitative analyses are reported for active (N2, CH4, CO, CO2, H2, O2, HF, HCl, H2S, SO2) and noble (He, Ar, Ne) gases released by crushing and step heating of magmatic-hydrothermal alunite from the Tapajós gold province in Brazil. This is the oldest known alunite (40Ar\\/39Ar age of 1.87 Ga), and because it has undergone minimal postdepositional thermal or tectonic strain,

  14. Noble gas evidence for a lower mantle component in MORBs from the southern East Pacific Rise: Decoupling of helium and neon isotope systematics

    Microsoft Academic Search

    Samuel Niedermann; Wolfgang Bach; Jörg Erzinger

    1997-01-01

    Abundances and isotopic compositions of all noble gases have been determined in basalt glasses from different latitudes on the 13–23°S section of the East Pacific Rise. In this region earlier work has identified isotopic signatures of Sr, Nd, and Pb as well as He which indicate a plume-like component admixed to the depleted MORB mantle between about 15.8° and 20.7°S

  15. Identifying Recharge Location Using Noble Gas Recharge Temperatures, Pajarito Plateau, New Mexico

    NASA Astrophysics Data System (ADS)

    Manning, A. H.; Dale, M.

    2008-12-01

    The solubility of noble gases in water is temperature dependent. Noble gas concentrations in ground water can therefore be used to determine the temperature at the water table at the recharge location (recharge temperature). The Pajarito Plateau in Northern New Mexico is an example of a hydrogeologic setting where noble gas recharge temperatures provide valuable information about recharge location which could be utilized in numerical model calibration. Previous studies have identified two potentially significant components of recharge to the regional aquifer underlying the plateau: (1) infiltration of precipitation in the Jemez Mountains adjacent to the plateau (mountain-block recharge); and (2) infiltration of stream water in the bottoms of canyons that traverse the plateau (plateau recharge). However, results regarding the relative importance of these two components are conflicting and uncertain. Their relative magnitude is of particular concern because Los Alamos National Laboratory is located on the plateau, and the susceptibility of the regional aquifer to lab-generated wastes depends directly upon the amount of plateau recharge. The Pajarito Plateau is an ideal location for applying noble gas recharge thermometry; mountain-block recharge should have cool recharge temperatures (<12°C) due to the shallow water table in the mountains, whereas plateau recharge should have distinctly warmer recharge temperatures (18 to 21°C) due to water table depths of 200 to 300m on the plateau. Noble gas samples were collected from wells screened in the regional aquifer across the plateau. Those analyzed to date from wells screened in the upper 30m of the aquifer yield recharge temperatures of 18 to 23°C. Exceptions are two wells located within 2km of the mountain front, which have recharge temperatures of 12 and 13°C. The one sample analyzed to date from a well screened deeper in the aquifer (125m below the water table) yields a recharge temperature of 11°C. Preliminary results therefore suggest that plateau recharge comprises nearly all of the water in the upper 30m of the regional aquifer throughout much of the plateau. However, the cooler recharge temperatures closer to the mountains and at depth indicate that mountain-block recharge may still constitute most of the total recharge to the aquifer; plateau recharge may be limited to a thin layer along the top of the aquifer at distances >2km from the mountain front.

  16. Regulating Greenhouse Gases

    NSDL National Science Digital Library

    KQED

    This video highlights the work of climate scientists in the Amazon who research the relationship between deforestation, construction of new dams, and increased amounts of greenhouse gases being exchanged between the biosphere and the atmosphere.

  17. Strongly interacting Fermi gases

    E-print Network

    Bakr, W.

    Strongly interacting gases of ultracold fermions have become an amazingly rich test-bed for many-body theories of fermionic matter. Here we present our recent experiments on these systems. Firstly, we discuss high-precision ...

  18. Photochemistry of biogenic gases

    NASA Technical Reports Server (NTRS)

    Levine, Joel S.

    1989-01-01

    The relationship between the biosphere and the atmosphere is examined, emphasizing the composition and photochemistry and chemistry of the troposphere and stratosphere. The reactions of oxygen, ozone, and hydroxyl are reviewed and the fate of the biogenic gases ammonia, methane, reduced sulfur species, reduced halogen species, carbon monoxide, nitric oxide, nitrous oxide, nitrogen, and carbon dioxide are described. A list is given of the concentration and sources of the various gases.

  19. ccsd00002151, Modelisation of transition and noble metal vicinal

    E-print Network

    ccsd­00002151, version 1 ­ 25 Jun 2004 Modelisation of transition and noble metal vicinal surfaces of transition and noble metal vicinal surfaces 3 the Density Functional Theory (DFT) or the Tight Binding Solides, Universit#19;e Paris Sud, F-91 405 Orsay, France #12; Abstract. The energetics of transition

  20. [Application of low noble alloys in telescoped crowns].

    PubMed

    Susuli?, T

    1989-01-01

    It is known that low noble alloys (Hera SG, Aurea-Heraus, Stabilor-Degussa, Midgold-Bego etc.) are used woredwide for the preparation of prosthetic constructions. For this reason attempts to produce low noble alloys with the properties equal to those of more expensive high noble alloys, are justified, as they are cheap and available to a great number of patients. The Yugoslav producer of dental materials "Zlatarna Celje" has produced a low noble alloy named Midor S. The comparative investigations of resistance to the mouth, performed at the University School of Dentistry in Ljubljana and in the Laboratory of Metallurgy of "Zlatarna Celje", have shown that this alloy was more resistant to corrosion than 22 karat, high noble alloy. In our Department Mikdor S was experimentally tested on telescoped crowns. The obtained results showed the satisfactory hardness and resistance to attrition between the internal and external crowns within the limits of tolerance which made it suitable for use. PMID:2489991

  1. Noble-metal-free plasmonic photocatalyst: hydrogen doped semiconductors

    PubMed Central

    Ma, Xiangchao; Dai, Ying; Yu, Lin; Huang, Baibiao

    2014-01-01

    The unique capacity of localized surface plasmon resonance (LSPR) offers a new opportunity to overcome the limited efficiency of semiconductor photocatalyst. Here we unravel that LSPR, which usually occurs in noble metal nanoparticles, can be realized by hydrogen doping in noble-metal-free semiconductor using TiO2 as a model photocatalyst. Moreover, its LSPR is located in infrared region, which supplements that of noble metal whose LSPR is generally in the visible region, making it possible to extend the light response of photocatalyst to infrared region. The near field enhancement is shown to be comparable with that of noble-metal nanoparticles, indicating that highly enhanced light absorption rate can be expected. The present work can provide a key guideline for the creation of highly efficient noble-metal-free plasmonic photocatalysts and have a much wider impact in infrared bioimaging and spectroscopy where infrared LSPR is essential. PMID:24496400

  2. Noble gas storage and delivery system for ion propulsion

    NASA Technical Reports Server (NTRS)

    Back, Dwight Douglas (Inventor); Ramos, Charlie (Inventor)

    2001-01-01

    A method and system for storing and delivering a noble gas for an ion propulsion system where an adsorbent bearing a noble gas is heated within a storage vessel to desorb the noble gas which is then flowed through a pressure reduction device to a thruster assembly. The pressure and flow is controlled using a flow restrictor and low wattage heater which heats an adsorbent bed containing the noble gas propellant at low pressures. Flow rates of 5-60 sccm can be controlled to within about 0.5% or less and the required input power is generally less than 50 W. This noble gas storage and delivery system and method can be used for earth orbit satellites, and lunar or planetary space missions.

  3. Noble gas residence times of saline waters within crystalline bedrock, Outokumpu Deep Drill Hole, Finland

    NASA Astrophysics Data System (ADS)

    Kietäväinen, Riikka; Ahonen, Lasse; Kukkonen, Ilmo T.; Niedermann, Samuel; Wiersberg, Thomas

    2014-11-01

    Noble gas residence times of saline groundwaters from the 2516 m deep Outokumpu Deep Drill Hole, located within the Precambrian crystalline bedrock of the Fennoscandian Shield in Finland, are presented. The accumulation of radiogenic (4He, 40Ar) and nucleogenic (21Ne) noble gas isotopes in situ together with the effects of diffusion are considered. Fluid samples were collected from depths between 180 and 2480 m below surface, allowing us to compare the modelled values with the measured concentrations along a vertical depth profile. The results show that while the concentrations in the upper part are likely affected by diffusion, there is no indication of diffusive loss at or below 500 m depth. Furthermore, no mantle derived gases were found unequivocally. Previous studies have shown that distinct vertical variation occurs both in geochemistry and microbial community structuring along the drill hole, indicating stagnant waters with no significant exchange of fluids between different fracture systems or with surface waters. Therefore in situ accumulation is the most plausible model for the determination of noble gas residence times. The results show that the saline groundwaters in Outokumpu are remarkably old, with most of the samples indicating residence times between ?20 and 50 Ma. Although being first order approximations, the ages of the fluids clearly indicate that their formation must predate more recent events, such as Quaternary glaciations. Isolation within the crust since the Eocene-Miocene epochs has also direct implications to the deep biosphere found at Outokumpu. These ecosystems must have been isolated for a long time and thus very likely rely on energy and carbon sources such as H2 and CO2 from groundwater and adjacent bedrock rather than from the ground surface.

  4. Polyacrylonitrile/noble metal/SiO? nanofibers as substrates for the amplified detection of picomolar amounts of metal ions through plasmon-enhanced fluorescence.

    PubMed

    Zhang, Han; Cao, Minhua; Wu, Wei; Xu, Haibo; Cheng, Si; Fan, Li-Juan

    2015-01-28

    Electrospun polymer/noble metal hybrid nanofibers have developed rapidly as surface-enhanced Raman scattering (SERS)-active substrates over the last few years. However, polymer/noble metal nanofibers with plasmon-enhanced fluorescence (PEF) activity have received no attention to date. Herein, we show a general and facile approach for the preparation of polyacrylonitrile (PAN)/noble metal/SiO2 nanofibrous mats with PEF activity for the first time by combining electrospinning and controlled silica coatings. These PEF-active nanofibrous mats can selectively improve the fluorescence intensity of conjugated polyelectrolytes (CPEs). Importantly, the CPE solution in the presence of a PAN/noble metal/SiO2 nanofibrous mat showed dramatic fluorescence quenching towards picomolar (pM) amounts of heavy metal ions, while the fluorescence of the CPE solution without the nanofibrous mat had no apparent quenching towards micromolar (?M) amounts of metal ions. The combination of the distance-dependent fluorescence enhancement performance of metal NPs and the ionic characteristics of the CPE solution makes the polymer/noble metal nanofibers promising substrates for greatly improving the detection sensitivity towards metal ions. We believe that this work provides a general strategy for preparing plasmon band-tuned PEF-active substrates with advantages including good selectivity, remarkable sensitivity and recyclability, which make them a preferable choice for practical sensing applications. PMID:25494487

  5. Hyperpolarized noble gas magnetic resonance imaging of the animal lung: Approaches and applications

    NASA Astrophysics Data System (ADS)

    Santyr, Giles E.; Lam, Wilfred W.; Parra-Robles, Juan M.; Taves, Timothy M.; Ouriadov, Alexei V.

    2009-05-01

    Hyperpolarized noble gas (HNG) magnetic resonance (MR) imaging is a very promising noninvasive tool for the investigation of animal models of lung disease, particularly to follow longitudinal changes in lung function and anatomy without the accumulated radiation dose associated with x rays. The two most common noble gases for this purpose are H3e (helium 3) and X129e (xenon 129), the latter providing a cost-effective approach for clinical applications. Hyperpolarization is typically achieved using spin-exchange optical pumping techniques resulting in ˜10 000-fold improvement in available magnetization compared to conventional Boltzmann polarizations. This substantial increase in polarization allows high spatial resolution (<1 mm) single-slice images of the lung to be obtained with excellent temporal resolution (<1 s). Complete three-dimensional images of the lungs with 1 mm slice thickness can be obtained within reasonable breath-hold intervals (<20 s). This article provides an overview of the current methods used in HNG MR imaging with an emphasis on ventilation studies in animals. Special MR hardware and software considerations are described in order to use the strong but nonrecoverable magnetization as efficiently as possible and avoid depolarization primarily by molecular oxygen. Several applications of HNG MR imaging are presented, including measurement of gross lung anatomy (e.g., airway diameters), microscopic anatomy (e.g., apparent diffusion coefficient), and a variety of functional parameters including dynamic ventilation, alveolar oxygen partial pressure, and xenon diffusing capacity.

  6. Development of Laser-Polarized Noble Gas Magnetic Resonance Imaging (MRI) Technology

    NASA Technical Reports Server (NTRS)

    Walsworth, Ronald L.

    2004-01-01

    We are developing technology for laser-polarized noble gas nuclear magnetic resonance (NMR), with the aim of enabling it as a novel biomedical imaging tool for ground-based and eventually space-based application. This emerging multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI)-e.g., of lung ventilation, perfusion, and gas-exchange. In addition, laser-polarized noble gases (3He and 1BXe) do not require a large magnetic field for sensitive NMR detection, opening the door to practical MRI with novel, open-access magnet designs at very low magnetic fields (and hence in confined spaces). We are pursuing two specific aims in this technology development program. The first aim is to develop an open-access, low-field (less than 0.01 T) instrument for MRI studies of human gas inhalation as a function of subject orientation, and the second aim is to develop functional imaging of the lung using laser-polarized He-3 and Xe-129.

  7. Conversion of ion-exchange resins, catalysts and sludges to glass with optional noble metal recovery using the GMODS process

    SciTech Connect

    Forsberg, C.W.; Beahm, E.C.

    1996-11-01

    Chemical processing and cleanup of waste streams (air and water) typically result in products, clean air, clean water, and concentrated hazardous residues (ion exchange resins, catalysts, sludges, etc.). Typically, these streams contain significant quantities of complex organics. For disposal, it is desirable to destroy the organics and immobilize any heavy metals or radioactive components into stable waste forms. If there are noble metals in the residues, it is desirable to recover these for reuse. The Glass Material Oxidation and Dissolution System (GMODS) is a new process that directly converts radioactive and hazardous chemical wastes to borosilicate glass. GMODS oxidizes organics with the residue converted to glass; converts metals, ceramics, and amorphous solids to glass; converts halides (eg chlorides) to borosilicate glass and a secondary sodium halide stream; and recovers noble metals. GMODS has been demonstrated on a small laboratory scale (hundreds of grams), and the equipment needed for larger masses has been identified.

  8. Experimental Investigation of the Low-Voltage Arc in Noble Gases

    Microsoft Academic Search

    R. J. Martin; J. E. Rowe

    1968-01-01

    An experimental investigation of the low-voltage arc mode of the hot-cathode discharge has been carried out in a diode utilizing planar electrode geometry. The investigation consisted predominantly of Langmuir-probe measurements of the discharge in a neon atmosphere. Measurements were also obtained in argon, xenon, and hydrogen and hydrogen-neon and argon-neon mixtures. The probes were of planar, guard-ringed geometry. The volt-ampere

  9. Noble gases in the Murchison meteorite - Possible relics of s-process nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Srinivasan, B.; Anders, E.

    1978-01-01

    The Murchison carbonaceous chondrite contains a new type of xenon component, enriched by up to 50 percent in five of the nine stable xenon isotopes, mass numbers 128 to 132. This component is released at 1200 to 1600 C from a severely etched mineral fraction. Krypton shows a similar but smaller enrichment in the isotopes 80 and 82. Neon and helium released in the same interval also are quite anomalous, being highly enriched in the isotopes 22 and 3. These patterns are strongly suggestive of three nuclear processes believed to take place in red giants: the s process (neutron capture on a slow time scale), helium burning, and hydrogen shell burning. If this interpretation is correct, then primitive meteorites contain yet another kind of alien, presolar material: dust grains ejected from red giants.

  10. Kaprada L(5\\/6) chondrite: Chemistry, petrography, noble gases and nuclear tracks

    Microsoft Academic Search

    N. Bhandari; S. V. S. Murty; R. R. Mahajan; G. Parthasarathy; P. N. Shukla; M. S. Sisodia; V. K. Rai

    2009-01-01

    A single stone weighing about 1.6kg fell in Kaprada village of south Gujarat, India in October, 2004. It has been studied for mineralogy, petrography, chemical and isotopic composition and cosmogenic effects. The olivine is 23.7% fayalite. The petrography, bulk chemistry and oxygen isotopic composition indicate that it belongs to L(5\\/6) group of chondrites. The cosmic ray exposure age of the

  11. Chemistry, Petrology, and Noble Gases of Lunar Highland Meteorite QUE 93069

    Microsoft Academic Search

    B. Spettel; G. Dreibus; A. Burghele; K. P. Jochum; L. Schultz; H. W. Weber; F. Wlotzka; H. Wanke

    1995-01-01

    Several pieces of QUE93069.6 of together 0.764 g were obtained for our investigations. 43 mg were used for rare gas analysis, all other material was homogenized for analyses by INAA, XRF, and SSMS techniques (Table 1). Available for investigation was also thin section, QUE93069.33. Petrology: Our PTS shows a fragmental breccia, as described by [1]. Fine, irregular metal particles are

  12. Relation of electron scattering cross-sections to drift measurement in noble gases

    E-print Network

    Stacey, Blake (Blake C.)

    2005-01-01

    We investigate the classic "inverse problem" of extracting collision and scattering cross sections from measurements of electron swarm behavior. A Monte Carlo technique for simulating electron motion through a gas of ...

  13. Quasi-phase-matching for third harmonic generation in noble gases employing ultrasound.

    PubMed

    Sapaev, U K; Babushkin, I; Herrmann, J

    2012-09-24

    We study a novel method of quasi-phase-matching for third harmonic generation in a gas cell using the periodic modulation of the gas pressure and thus of the third order nonlinear coefficient in the axial direction created by an ultrasound wave. Using a comprehensive numerical model we describe the quasi-phase matched third harmonic generation of UV (at 266 nm) and VUV pulses (at 133 nm) by using pump pulses at 800 nm and 400 nm, respectively, with pulse energy in the range from 3 mJ to 1 J. In addition, using chirped pump pulses, the generation of sub-20-fs VUV pulses without the necessity for an external chirp compensation is predicted. PMID:23037426

  14. Production of noble gases near the surface of Europa and the prospects for in situ chronology

    Microsoft Academic Search

    T. D. Swindle; J. Masarik; D. Kollárb; K. J. Kimc; R. C. Reedy

    2005-01-01

    The age of the surface of Europa is probably tens of Myr or less, but is poorly constrained. Two different geochronology schemes could potentially be applied to near-surface samples to provide far more precise ages. First, the surface salts apparently contain enough potassium to make potassium–argon dating feasible. Second, the bombardment of the surface with both galactic cosmic rays and

  15. Depth variation of cosmogenic noble gases in the approximately 120-kg Keyes chondrite.

    NASA Technical Reports Server (NTRS)

    Wright, R. J.; Reynolds, M. A.; Bogard, D. D.; Simms, L. A.

    1973-01-01

    Cosmic ray spallation produced He-3, Ne-21, Ne-22 and Ar-38 have been measured as a function of depth in three mutually perpendicular cores (56, 51, and 21 cm) taken from the 120-kg L chondrite found near Keyes, Oklahoma. The data obtained represent the first experimental determination of the depth variation in the production rates of these cosmogenic nuclides in a single stone meteorite. Fifteen samples across the 56-cm core showed maximum concentration changes of 14% He-3, 28% Ne-21, 19% He-3/Ne-21, and 5% Ne-22/Ne-21. The 51-cm core showed somewhat smaller concentration changes.

  16. Reconstructing the Paleo-Limnologic Evolution of Lake Bonney, Antarctica using Dissolved Noble Gases

    NASA Astrophysics Data System (ADS)

    Warrier, R. B.; Castro, M.; Hall, C. M.; Kenig, F. P.; Doran, P. T.

    2013-12-01

    The McMurdo Dry Valleys, situated on the western coast of the Ross Sea are the largest ice-free region in Antarctica. Lake Bonney (LB), located in western Taylor valley, one of the main east-west dry valleys, has two lobes, East Lake Bonney (ELB) and West Lake Bonney (WLB), which are separated by a narrow straight with a ~13 m deep sill. Because the evolution of LB is ultimately controlled by climate and because there are no reliable millennial-scale continental records of climate other than the Taylor Dome ice core in this region of Antarctica, a number of studies have reconstructed the paleolimnologic history of LB using diverse tools to try to reconstruct the history of the lake, and thus, the climate evolution in this area. However, many open questions remain with respect to the paleo-limnologic evolution of LB. To further place constraints on the evolution of LB, we analyzed 23 lake samples collected between 5 and ~40 m depth from both ELB and WLB for He and Ar concentrations as well as isotopic ratios. Preliminary results show that samples present He excesses up to two and three orders of magnitude with respect to air saturated water (ASW) in ELB and WLB, respectively. While He excesses generally increase with depth in WLB suggesting accumulation of 4He over time, a similar correlation with depth is not observed for ELB samples, indicating a more complex evolutionary history in this lobe. Measured R/Ra He isotopic ratios, where Ra is the atmospheric 3He/4He ratio, vary between 0.20-0.61 and 0.16-0.22 for ELB and WLB respectively, and indicate that observed He excesses are predominantly crustal in origin, with a small (<~5%) mantle contribution. In contrast, measured 40Ar/36Ar ratios indicate that Ar concentrations at all depths in ELB are atmospheric in origin while WLB samples below the sill indicate addition of excess 40Ar, likely of radiogenic origin. Preliminary estimates of water residence times based on measured He excesses and crustal production ratios from basement rocks point to maximum water ages of ~5 kyrs and ~500 kyrs for the deep waters of ELB and WLB, respectively. Similarly, a maximum residence time of ~500 kyrs was obtained for bottom waters of WLB assuming a crustal origin for the observed excess 40Ar. These preliminary age results are maximum estimations and assume that all He and Ar excesses are entirely of crustal origin. Our preliminary results indicate that the WLB waters have been isolated from the atmosphere for a much longer period of time than ELB waters and point to a very different evolution of both lobes. In addition, these maximum WLB ages obtained are much younger than previously thought (~1-5 Ma).

  17. On the abundances of noble and biologically relevant gases in Lake Vostok, Antarctica.

    PubMed

    Mousis, Olivier; Lakhlifi, Azzedine; Picaud, Sylvain; Pasek, Matthew; Chassefière, Eric

    2013-04-01

    Motivated by the possibility of comparing theoretical predictions of Lake Vostok's composition with future in situ measurements, we investigated the composition of clathrates that are expected to form in this environment from the air supplied to the lake by melting ice. To establish the best possible correlation between the lake water composition and that of air clathrates formed in situ, we used a statistical thermodynamic model based on the description of the guest-clathrate interaction by a spherically averaged Kihara potential with a nominal set of potential parameters. We determined the fugacities of the different volatiles present in the lake by defining a "pseudo" pure substance dissolved in water owning the average properties of the mixture and by using the Redlich-Kwong equation of state to mimic its thermodynamic behavior. Irrespective of the clathrate structure considered in our model, we found that xenon and krypton are strongly impoverished in the lake water (a ratio in the 0.04-0.1 range for xenon and a ratio in the ? 0.15-0.3 range for krypton) compared to their atmospheric abundances. Argon and methane were also found to be depleted in the Lake Vostok water by factors in the 0.5-0.95 and 0.3-0.5 ranges, respectively, compared to their atmospheric abundances. On the other hand, the carbon dioxide abundance was found to be substantially enriched in the lake water compared to its atmospheric abundance (by a factor in the 1.6-5 range at 200 residence times). The comparison of our predictions of the CO2 and CH4 mole fractions in Lake Vostok with future in situ measurements will allow disentangling between the possible supply sources. PMID:23758192

  18. Release of Implanted Noble Gases from Metallic Glass Vitreloy During Pyrolysis

    NASA Technical Reports Server (NTRS)

    Meshik, A. P.; Hohenberg, C. M.; Burnett, D. S.; Woolum, D. S.

    2000-01-01

    Vitreloy, a metallic vitreous glass, was examined as a potential target material for the Genesis Mission solar wind collector. Stepped pyrolysis revealed that He and Ne implanted in Vitreloy were efficiently re-trapped during phase transitions.

  19. Strengthening gold-gold bonds by complexing gold clusters with noble gases

    E-print Network

    Ghiringhelli, Luca M

    2015-01-01

    We report an unexpectedly strong and complex chemical bonding of rare-gas atoms to neutral gold clusters. The bonding features are consistently reproduced at different levels of approximation within density-functional theory and beyond: from GGA, through hybrid and double-hybrid functionals, up to renormalized second-order perturbation theory. The main finding is that the adsorption of Ar, Kr, and Xe reduces electron-electron repulsion within gold dimer, causing strengthening of the Au-Au bond. Differently from the dimer, the rare-gas adsorption effects on the gold trimer's geometry and vibrational frequencies are mainly due to electron occupation of the trimer's lowest unoccupied molecular orbital. For the trimer, the theoretical results are also consistent with far-infrared multiple photon dissociation experiments.

  20. A generic biokinetic model for noble gases with application to radon

    SciTech Connect

    Leggett, Richard Wayne [ORNL; Marsh, James [Health Protection Agency of Great Britain; Gregoratto, Demetrio [Health Protection Agency of Great Britain; Blanchardon, Eric [IRSN

    2013-01-01

    The International Commission for Radiological Protection (ICRP) currently uses a dose conversion coefficient to calculate effective dose per unit exposure to radon and its progeny. The coefficient is derived by dividing the detriment associated with unit exposure to radon, as estimated from epidemiological studies, by the detriment per unit effective dose, as estimated mainly from atomic bomb survivor data and animal studies. In a recent statement the ICRP indicated that future guidance on exposure to radon and its progeny will be developed in the same way as guidance for any other radionuclide. That is, intake of radon and progeny will be limited on the basis of effective dose coefficients derived from biokinetic and dosimetric models. This paper proposes a biokinetic model for systemic (absorbed) radon for use in the calculation of dose coefficients for inhaled or ingested radon. The model is based largely on physical laws governing transfer of a non-reactive and soluble gas between materials. Model predictions are shown to be consistent with results of controlled studies of the fate of internally deposited radon in human subjects.

  1. Adsorption of noble gases on individual suspended single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lee, Hao-Chun; Wang, Zenghui; Roy, Richard; Fredrickson, Erik; Vilches, Oscar; Cobden, David

    2012-02-01

    Suspended single-walled carbon nanotubes can act as nanomechanical resonators, offering the ability to detect an adsorbed substance with very high sensitivity via the frequency shift due to the adsorbed mass. By measuring the resonance frequency electrically in the presence of vapors at controlled temperature and pressure we have obtained isotherms for 4He, Ar, Kr and Xe, on multiple nanotubes. The behavior resembles that on graphite but with notable differences, including weaker binding energies. The lower binding allows access to behavior at lower 2D chemical potential than on conventional substrates. For 4He the binding energy is reduced by as much as a factor of two. For Ar the derived two-dimensional phase diagram is similar to that on conventional substrates. For Kr there is variation between nanotubes which may be related to commensurability and area per site on the surface of a cylinder. Work supported by NSF DMR 0907690.

  2. Synergetic effect in a mixture of noble gases around the Paschen minimum

    SciTech Connect

    Despotovic, Dejan; Cvetic, Jovan; Stankovic, Koviljka; Osmokrovic, Predrag, E-mail: opredrag@verat.net [Faculty of Electrical Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, 11000 Belgrade (Serbia)] [Faculty of Electrical Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, 11000 Belgrade (Serbia)

    2014-01-15

    DC and pulse breakdown in the He-Ar gas mixture are investigated for small pressures and inter-electrode gaps. Expressions for calculating the breakdown voltage of a gas mixture are derived, assuming that breakdown occurs by way of the Townsend breakdown mechanism and that Maxwell spectrum can be used for the free electron gas. The parameters considered in experiments have been chosen so as to be of interest in designing gas-filled surge arresters. The obtained results demonstrate that the derived breakdown voltage expressions are correct, and that a suitable choice of parameters can produce a positive synergetic effect with regard to gas-filled surge arrester design. The latter issue is especially interesting for lowering the dc breakdown voltage of unconditioned electrodes.

  3. Evidence for multiple magma ocean outgassing and atmospheric loss episodes from mantle noble gases

    NASA Astrophysics Data System (ADS)

    Tucker, Jonathan M.; Mukhopadhyay, Sujoy

    2014-05-01

    The energy associated with giant impacts is large enough to generate global magma oceans during Earth's accretion. However, geochemical evidence requiring a terrestrial magma ocean is scarce. Here we present evidence for at least two separate magma ocean outgassing episodes on Earth based on the ratio of primordial 3He to 22Ne in the present-day mantle. We demonstrate that the depleted mantle 3He/22Ne ratio is at least 10 while a more primitive mantle reservoir has a 3He/22Ne ratio of 2.3 to 3. The 3He/22Ne ratios of the mantle reservoirs are higher than possible sources of terrestrial volatiles, including the solar nebula ratio of 1.5. Therefore, a planetary process must have raised the mantle's 3He/22Ne ratio. We show that long-term plate tectonic cycling is incapable of raising the mantle 3He/22Ne ratio and may even lower it. However, ingassing of a gravitationally accreted nebular atmosphere into a magma ocean on the proto-Earth explains the 3He/22Ne and 20Ne/22Ne ratios of the primitive mantle reservoir. Increasing the mantle 3He/22Ne ratio to a value of 10 in the depleted mantle requires at least two episodes of atmospheric blow-off and magma ocean outgassing associated with giant impacts during subsequent terrestrial accretion. The preservation of a low 3He/22Ne ratio in a primitive reservoir sampled by plumes suggests that the later giant impacts, including the Moon-forming giant impact, did not generate a whole mantle magma ocean. Atmospheric loss episodes associated with giant impacts provide an explanation for Earth's subchondritic C/H, N/H, and Cl/F elemental ratios while preserving chondritic isotopic ratios. If so, a significant proportion of terrestrial water and potentially other major volatiles were accreted prior to the last giant impact, otherwise the fractionated elemental ratios would have been overprinted by the late veneer.

  4. On the abundances of noble and biologically relevant gases in Lake Vostok, Antarctica

    E-print Network

    Mousis, Olivier; Picaud, Sylvain; Pasek, Matthew; Chassefière, Eric

    2013-01-01

    Motivated by the possibility of comparing theoretical predictions of Lake Vostok's composition with future in situ measurements, we investigate the composition of clathrates that are expected to form in this environment from the air supplied to the lake by melting ice. In order to establish the best possible correlation between the lake water composition with that of air clathrates formed in situ, we use a statistical thermodynamic model based on the description of the guest-clathrate interaction by a spherically averaged Kihara potential with a nominal set of potential parameters. We determine the fugacities of the different volatiles present in the lake by defining a "pseudo" pure substance dissolved in water owning the average properties of the mixture and by using the Redlich-Kwong equation of state to mimic its thermodynamic behavior. Irrespective of the clathrate structure considered in our model, we find that xenon and krypton are strongly impoverished in the lake water (a ratio in the 0.04--0.1 range ...

  5. Noble gases identify the mechanisms of fugitive gas contamination in drinking-water wells overlying the

    E-print Network

    Jackson, Robert B.

    and hydraulic fracturing have substantially increased hydrocarbon recovery from black shales and other hydrocarbons (ethane, propane, etc.) in drinking water, for instance, remains controversial and requires

  6. Trapping Planetary Noble Gases During the Fischer-Tropsch-Type Synthesis of Organic Materials

    NASA Technical Reports Server (NTRS)

    Nuth, Joseph A.; Johnson, N. M.; Meshik, A.

    2010-01-01

    When hydrogen, nitrogen and CO arc exposed to amorphous iron silicate surfaces at temperatures between 500 - 900K, a carbonaceous coating forms via Fischer-Tropsch type reactions!, Under normal circumstances such a catalytic coating would impede or stop further reaction. However, we find that this coating is a better catalyst than the amorphous iron silicates that initiate these rcactions:u . The formation of a self-perpetuating catalytic coating on grain surfaces could explain the rich deposits of macromolecular carbon found in primitive meteorites and would imply that protostellar nebulae should be rich in organic materiaL Many more experiments are needed to understand this chemical system and its application to protostellar nebulae.

  7. Laser microprobe analyses of noble gas isotopes and halogens in fluid inclusions: Analyses of microstandards and synthetic inclusions in quartz

    USGS Publications Warehouse

    Böhlke, J.K.; Irwin, J.J.

    1992-01-01

    Ar, Kr, Xe, Cl, Br, I, and K abundances and isotopic compositions have been measured in microscopic fluid inclusions in minerals by noble gas mass spectrometry following neutron irradiation and laser extraction. The laser microprobe noble gas mass spectrometric (LMNGMS) technique was quantified by use of microstandards, including air-filled capillary tubes, synthetic basalt glass grains, standard hornblende grains, and synthetic fluid inclusions in quartz. Common natural concentrations of halogens (Cl, Br, and I) and noble gases (Ar and Kr) in trapped groundwaters and hydrothermal fluids can be analyzed simultaneously by LMNGMS in as little as 10-11 L of inclusion fluid, with accuracy and precision to within 5-10% for element and isotope ratios. Multicomponent element and isotope correlations indicate contaminants or persistent reservoirs of excess Xe and/or unfractionated air in some synthetic and natural fluid inclusion samples. LMNGMS analyses of natural fluid inclusions using the methods and calibrations reported here may be used to obtain unique information on sources of fluids, sources of fluid salinity, mixing, boiling (or unmixing), and water-rock interactions in ancient fluid flow systems. ?? 1992.

  8. Gases: Characteristics and Properties

    NSDL National Science Digital Library

    Brieske, Joel A.

    The first site related to ideal gas, called Ideal and Real Gas Laws, is maintained by Liina Ladon of Townsen University (1). Visitors can read about the properties of ideal gases, what the ideal gas law is, how to use it, and much more. The next site, titled Gas Laws, (2) is offered by the Ohio State University Department of Chemistry. This interactive site contains Shockwave movies of animations and audio files that describe what a gas is, the Ideal Gas Law equation, mixtures of gases, and problems using the ideal gas law. The University of Oregon site, Virtual Laboratory, teaches about the ideal gas law on the Welcome to the Pressure Chamber page (3). Those who enjoy online interaction will enjoy being able to control the action of a piston in a pressure chamber to see how the gases inside react. The fourth site includes another fun multimedia activity related to ideal gases provided by the Department of Physics and Astronomy at Western Washington University. The Air Filled Balloon in Liquid Nitrogen (4) movie shows an actual experiment of the effects on a balloon that's covered with liquid nitrogen. The page contains some additional information on the science behind the observations. The next site, called Ideal Gas Equations (5) is an online calculator that's part of Kean University's Department of Geology and Meteorology Web site. Users can calculate the pressure, volume, or temperature of a gas by inputting known variables into the various forms. Several methods and variations of calculating the values are provided as well as brief instructions. The next page from North Carolina State University's Basic Concepts in Environmental Science Web site is called Characteristics of Gases (6). Part of a larger learning module, the lesson plans objective is to use the ideal gas law to determine gas volumes at different absolute temperatures and absolute pressures. Everything needed to conduct the activity is provided including links to a volume calculator and practice problems. The seventh site is another animation that illustrates how gases react, called Molecular Model for an Ideal Gas (7). By changing the number of molecules in the chamber, their velocity, and the pressure and width of the container, users get to see how the molecules react to the conditions. The last site, Gases and Their Properties, is maintained by the Electronic Teaching Assistance Program(8). Students learn about the history of gas science, how gas laws describe ideal gases, what Dalton's Law and Graham's Law are, and much more.

  9. 40 CFR 86.1314-94 - Analytical gases.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines...CO2 . respectively, using nitrogen as the diluent. (b) Gases...of the nominal value using nitrogen as the diluent. (e...allowable zero gas (air or nitrogen) impurity...

  10. 40 CFR 86.114-94 - Analytical gases.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles...and CO2 respectively using nitrogen as the diluent. (2) Gases...of the nominal value, using nitrogen as the diluent. (5...allowable zero gas (air or nitrogen) impurity...

  11. 40 CFR 86.114-94 - Analytical gases.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles...and CO2 respectively using nitrogen as the diluent. (2) Gases...of the nominal value, using nitrogen as the diluent. (5...allowable zero gas (air or nitrogen) impurity...

  12. 40 CFR 86.114-94 - Analytical gases.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles...and CO2 respectively using nitrogen as the diluent. (2) Gases...of the nominal value, using nitrogen as the diluent. (5...allowable zero gas (air or nitrogen) impurity...

  13. 40 CFR 86.1314-94 - Analytical gases.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines...CO2 . respectively, using nitrogen as the diluent. (b) Gases...of the nominal value using nitrogen as the diluent. (e...allowable zero gas (air or nitrogen) impurity...

  14. 40 CFR 86.114-94 - Analytical gases.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles...and CO2 respectively using nitrogen as the diluent. (2) Gases...of the nominal value, using nitrogen as the diluent. (5...allowable zero gas (air or nitrogen) impurity...

  15. 40 CFR 86.114-94 - Analytical gases.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles...and CO2 respectively using nitrogen as the diluent. (2) Gases...of the nominal value, using nitrogen as the diluent. (5...allowable zero gas (air or nitrogen) impurity...

  16. 40 CFR 86.1314-94 - Analytical gases.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines...CO2 . respectively, using nitrogen as the diluent. (b) Gases...of the nominal value using nitrogen as the diluent. (e...allowable zero gas (air or nitrogen) impurity...

  17. 40 CFR 86.1314-94 - Analytical gases.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines...CO2 . respectively, using nitrogen as the diluent. (b) Gases...of the nominal value using nitrogen as the diluent. (e...allowable zero gas (air or nitrogen) impurity...

  18. NG09 And CTBT On-Site Inspection Noble Gas Sampling and Analysis Requirements

    NASA Astrophysics Data System (ADS)

    Carrigan, Charles R.; Tanaka, Junichi

    2010-05-01

    A provision of the Comprehensive Test Ban Treaty (CTBT) allows on-site inspections (OSIs) of suspect nuclear sites to determine if the occurrence of a detected event is nuclear in origin. For an underground nuclear explosion (UNE), the potential success of an OSI depends significantly on the containment scenario of the alleged event as well as the application of air and soil-gas radionuclide sampling techniques in a manner that takes into account both the suspect site geology and the gas transport physics. UNE scenarios may be broadly divided into categories involving the level of containment. The simplest to detect is a UNE that vents a significant portion of its radionuclide inventory and is readily detectable at distance by the International Monitoring System (IMS). The most well contained subsurface events will only be detectable during an OSI. In such cases, 37 Ar and radioactive xenon cavity gases may reach the surface through either "micro-seepage" or the barometric pumping process and only the careful siting of sampling locations, timing of sampling and application of the most site-appropriate atmospheric and soil-gas capturing methods will result in a confirmatory signal. The OSI noble gas field tests NG09 was recently held in Stupava, Slovakia to consider, in addition to other field sampling and analysis techniques, drilling and subsurface noble gas extraction methods that might be applied during an OSI. One of the experiments focused on challenges to soil-gas sampling near the soil-atmosphere interface. During withdrawal of soil gas from shallow, subsurface sample points, atmospheric dilution of the sample and the potential for introduction of unwanted atmospheric gases were considered. Tests were designed to evaluate surface infiltration and the ability of inflatable well-packers to seal out atmospheric gases during sample acquisition. We discuss these tests along with some model-based predictions regarding infiltration under different near-surface hydrologic conditions. We also consider how naturally occurring as well as introduced (e.g., SF6) soil-gas tracers might be used to guard against the possibility of atmospheric contamination of soil gases while sampling during an actual OSI. The views expressed here do not necessarily reflect the opinion of the United States Government, the United States Department of Energy, or Lawrence Livermore National Laboratory. This work has been performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-418791

  19. RADIATION CHEMISTRY: GASES

    Microsoft Academic Search

    Lind

    1961-01-01

    A discussion is given of the vsriety of reactions occurring in the ; irradiation of single- and multi-component gaseous systems. The ozonization of ; oxygen is described as an example of one-component gas reactions. In multi-; component systems important reactions involve oxidation, hydrogonation, ; polymerization, reverse reactions, and foreign gases. The use of mass ; spectrometry in the study of

  20. Gases in Tektite Bubbles.

    PubMed

    O'keefe, J A; Lowman, P D; Dunning, K L

    1962-07-20

    Spectroscopic analysis of light produced by electrodeless discharge in a tektite bubble showed the main gases in the bubble to be neon, helium, and oxygen. The neon and helium have probably diffused in from the atmosphere, while the oxygen may be atmospheric gas incorporated in the tektite during its formation. PMID:17801113

  1. Catalytic Generation of Lift Gases for Balloons

    NASA Technical Reports Server (NTRS)

    Zubrin, Robert; Berggren, Mark

    2011-01-01

    A lift-gas cracker (LGC) is an apparatus that generates a low-molecular-weight gas (mostly hydrogen with smaller amounts of carbon monoxide and/or carbon dioxide) at low gauge pressure by methanol reforming. LGCs are undergoing development for use as sources of buoyant gases for filling zero-gauge-pressure meteorological and scientific balloons in remote locations where heavy, high-pressure helium cylinders are not readily available. LGCs could also be used aboard large, zero-gauge-pressure, stratospheric research balloons to extend the duration of flight.

  2. Noble gas storage and transport in the terrestrial mantle: the importance of grain boundaries

    NASA Astrophysics Data System (ADS)

    Burnard, P.; Demouchy, S.; Arnaud, N. O.

    2012-12-01

    Incompatible elements preferentially segregate to grain boundaries (GB) of mantle minerals, as opposed being dissolved in the crystal matrix, providing significant reservoirs of certain elements. Lattice strain models suggest that noble gases (NG) should be enriched in GBs [1,2]. In order to test NG partitioning between crystal and GB and to investigate diffusion of NG in grain boundaries, 4He and 40Ar were incorporated into single crystal olivine (SCO) and polycrystalline olivine with a c. 10 ?m grainsize (PCO, with grain boundaries) via annealing experiments at 300 MPa and 1150 C in a Paterson-type press. SCO and PCO were then analyzed by traditional noble gas mass spectrometry. Incremental heating of PCO identifies NG sites with different activation energies (Ea). A very low Ea Ar site (c. 0 kJ mol-1) is most probably simply adsorbed Ar. However, two higher energy sites with Ea = 50+-12 and 260+-75 kJ mol-1 are interpreted to represent grain boundary and matrix hosted Ar, respectively. Similarly, He release curves can be interpreted in terms of low energy (=GB, Ea =8+-1 kJ mol-1) and matrix (c. 175 kJ mol-1) hosted sites. The high Ea values are broadly consistent with previous measurements of matrix-hosted NG diffusivities measured by stepped heating [3, 4]. Our experiments also allow the partition coefficient between GB and matrix olivine to be measured. For He, GB/matrix is > 10^3 compared to c. 5 x10^2 for Ar. These experiments have implications for NG storage and transport in the mantle. 1) Mantle grainsize will strongly influence NG partitioning, with NG becoming less incompatible in fine grained lithologies. 2) Effective diffusion properties for fine grained aggregates will be governed by GB diffusion; diffusivities depend on poorly constrained diffusion domain sizes, but it seems likely that effective He diffusion through bulk mantle will be of the order 10^8 cm2 s-1. As a result, mantle heterogeneities less than 0.5 km will not preserve He isotopic or concentration contrasts. 3) Substantial elemental fractionation of NG could result from GB - matrix partitioning, with GB preferentially enriched in light noble gases (He, Ne).Figure. He and Ar stepped heating of polycrystalline olivine (PCO). Top = Ar, bottom = He. Solid symbols used for calculating diffusivities of grain boundaries and matrix sited He and Ar.

  3. Mitigation of hydrogen by oxidation using nitrous oxide and noble metal catalysts

    SciTech Connect

    Britton, M.D.

    1995-01-19

    This test studied the ability of a blend of nuclear-grade, noble-metal catalysts to catalyze a hydrogen/nitrous oxide reaction in an effort to mitigate a potential hydrogen (H{sub 2}) gas buildup in the Hanford Site Grout Disposal Facility. For gases having H{sub 2} and a stoichiometric excess of either nitrous oxide or oxygen, the catalyst blend can effectively catalyze the H{sub 2} oxidation reaction at a rate exceeding 380 {mu}moles of H{sub 2} per hour per gram of catalyst ({mu}mol/h/g) and leave the gas with less than a 0.15 residual H{sub 2} Concentration. This holds true in gases with up to 2.25% water vapor and 0.1% methane. This should also hold true for gases with up to 0.1% carbon monoxide (CO) but only until the catalyst is exposed to enough CO to block the catalytic sites and stop the reaction. Gases with ammonia up to 1% may be slightly inhibited but can have reaction rates greater than 250 {mu}mol/h/g with less than a 0.20% residual H{sub 2} concentration. The mechanism for CO poisoning of the catalyst is the chemisorption of CO to the active catalyst sites. The CO sorption capacity (SC) of the catalyst is the total amount of CO that the catalyst will chemisorb. The average SC for virgin catalyst was determined to be 19.3 {plus_minus} 2.0 {mu}moles of CO chemisorbed to each gram of catalyst ({mu}mol/g). The average SC for catalyst regenerated with air was 17.3 {plus_minus} 1.9 {mu}mol/g.

  4. Guidance Document CompressedGases

    E-print Network

    , oxygen and other oxidizing gases. Flammable gases can be ignited by heat, flame, hot object or static electricity. Oxygen by itself does not burn, but it will support or accelerate combustion of flammable

  5. Noble gas tracing of groundwater/coalbed methane interaction in the San Juan Basin, USA

    NASA Astrophysics Data System (ADS)

    Zhou, Zheng; Ballentine, Chris J.; Kipfer, Rolf; Schoell, Martin; Thibodeaux, Steve

    2005-12-01

    The San Juan Basin natural gas field, located in northwestern New Mexico and southwestern Colorado in the USA, is a case-type coalbed methane system. Groundwater is thought to play a key role in both biogenic methane generation and the CO 2 sequestration potential of coalbed systems. We show here how noble gases can be used to construct a physical model that describes the interaction between the groundwater system and the produced gas. We collected 28 gas samples from producing wells in the artesian overpressured high production region of the basin together with 8 gas samples from the underpressured low production zone as a control. Stable isotope and major species determination clearly characterize the gas in the high production region as dominantly biogenic in origin, and the underpressured low producing region as having a significant admix of thermogenic coal gas. 3He/ 4He ratios increase from 0.0836R a at the basin margin to 0.318R a towards the center, indicating a clear but small mantle He signature in all gases. Coherent fractionation of water-derived 20Ne/ 36Ar and crustal 4He/ 40Ar* are explained by a simple Rayleigh fractionation model of open system groundwater degassing. Low 20Ne concentrations compared to the model predicted values are accounted for by dilution of the groundwater-associated gas by desorbed coalbed methane. This Rayleigh fractionation and dilution model together with the gas production history allows us to quantify the amount of water involved in gas production at each well. The quantified water volumes in both underpressured and overpressured zones range from 1.7 × 10 3 m 3 to 4.2 × 10 5 m 3, with no clear distinction between over- and underpressured production zones. These results conclusively show that the volume of groundwater seen by coal does not play a role in determining the volume of methane produced by secondary biodegradation of these coalbeds. There is no requirement of continuous groundwater flow for renewing the microbes or nutrient components. We furthermore observe strong mass related isotopic fractionation of 20Ne/ 22Ne and 38Ar/ 36Ar isotopic ratios. This can be explained by a noble gas concentration gradient in the groundwater during gas production, which causes diffusive partial re-equilibration of the noble gas isotopes. It is important for the study of other systems in which extensive groundwater degassing may have occurred to recognize that severe isotopic fractionation of air-derived noble gases can occur when such concentration gradients are established during gas production. Excess air-derived Xe and Kr in our samples are shown to be related to the diluting coalbed methane and can only be accounted for if Xe and Kr are preferentially and volumetrically trapped within the coal matrix and released during biodegradation to form CH 4.

  6. Thermal conductivity of graphene nanoribbons in noble gaseous environments

    SciTech Connect

    Zhong, Wei-Rong, E-mail: wrzhong@hotmail.com; Xu, Zhi-Cheng; Zheng, Dong-Qin [Department of Physics and Siyuan Laboratory, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Ai, Bao-Quan, E-mail: aibq@scnu.edu.cn [Laboratory of Quantum Information Technology, ICMP and SPTE, South China Normal University, Guangzhou 510006 (China)

    2014-02-24

    We investigate the thermal conductivity of suspended graphene nanoribbons in noble gaseous environments using molecular dynamics simulations. It is reported that the thermal conductivity of perfect graphene nanoribbons decreases with the gaseous pressure. The decreasing is more obvious for the noble gas with large atomic number. However, the gaseous pressure cannot change the thermal conductivity of defective graphene nanoribbons apparently. The phonon spectra of graphene nanoribbons are also provided to give corresponding supports.

  7. High voltage in noble liquids for high energy physics

    NASA Astrophysics Data System (ADS)

    Rebel, B.; Hall, C.; Bernard, E.; Faham, C. H.; Ito, T. M.; Lundberg, B.; Messina, M.; Monrabal, F.; Pereverzev, S. P.; Resnati, F.; Rowson, P. C.; Soderberg, M.; Strauss, T.; Tomas, A.; Va'vra, J.; Wang, H.

    2014-08-01

    A workshop was held at Fermilab November 8-9, 2013 to discuss the challenges of using high voltage in noble liquids. The participants spanned the fields of neutrino, dark matter, and electric dipole moment physics. All presentations at the workshop were made in plenary sessions. This document summarizes the experiences and lessons learned from experiments in these fields at developing high voltage systems in noble liquids.

  8. The Chemistry of Biological Gases

    Microsoft Academic Search

    D. Jeannean Carver; Lisa A. Palmer

    \\u000a Today there are at least four biological gases: oxygen (O2), nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide\\u000a (H2S). Except for molecular oxygen, many of these gases were originally known for their detrimental physiological effects.\\u000a However, the current consensus suggests that these gases play a role in signal transduction, modulating physiological function.\\u000a The roles of these gases are complex

  9. Kinetic Theory of Gases

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The theory, developed in the nineteenth century, notably by Rudolf Clausius (1822-88) and James Clerk Maxwell (1831-79), that the properties of a gas (temperature, pressure, etc) could be described in terms of the motions (and kinetic energy) of the molecules comprising the gases. The theory has wide implications in astrophysics. In particular, the perfect gas law, which relates the pressure, vol...

  10. Sudden releases of gases

    NASA Astrophysics Data System (ADS)

    Chaloupecká, Hana; Ja?our, Zbyn?k; Jur?áková, Klára; Kuka?ka, Libor; Nosek, Št?pán

    2014-03-01

    Conurbations all over the world have enlarged for numberless years. The accidental or intentional releases of gases become more frequent. Therefore, these crises situations have to be studied. The aim of this paper is to describe experiments examining these processes that were carried out in the laboratory of Environmental Aerodynamics of the Institute of Thermomechanics AS CR in Nový Knín. Results show huge puff variability from replica to replica.

  11. Greenhouse Gases Exposed

    NSDL National Science Digital Library

    Victoria Babcock

    In this activity, students learn about the relationship between greenhouse gases and global warming through a simple teacher demo or hands-on lab activity. Everyday materials are used: beakers, baking soda, vinegar, candle, thermometers, heat source such as a goose-necked lamp, etc. Students shine a light onto three thermometers: a control, an upside down beaker w/ a thermometer and air, and a beaker in which CO2 had been poured.

  12. Modeling Noble Gas Transport and Detection for The Comprehensive Nuclear-Test-Ban Treaty

    NASA Astrophysics Data System (ADS)

    Sun, Yunwei; Carrigan, Charles R.

    2014-03-01

    Detonation gases released by an underground nuclear test include trace amounts of 133Xe and 37Ar. In the context of the Comprehensive Nuclear Test Ban Treaty, On Site Inspection Protocol, such gases released from or sampled at the soil surface could be used to indicate the occurrence of an explosion in violation of the treaty. To better estimate the levels of detectability from an underground nuclear test (UNE), we developed mathematical models to evaluate the processes of 133Xe and 37Ar transport in fractured rock. Two models are developed respectively for representing thermal and isothermal transport. When the thermal process becomes minor under the condition of low temperature and low liquid saturation, the subsurface system is described using an isothermal and single-gas-phase transport model and barometric pumping becomes the major driving force to deliver 133Xe and 37Ar to the ground surface. A thermal test is simulated using a nonisothermal and two-phase transport model. In the model, steam production and bubble expansion are the major processes driving noble gas components to ground surface. After the temperature in the chimney drops below boiling, barometric pumping takes over the role as the major transport process.

  13. Noble magnetic barriers in the ASDEX UG tokamak

    NASA Astrophysics Data System (ADS)

    Ali, Halima; Punjabi, Alkesh; Vazquez, Justin

    The second-order perturbation method of creating invariant tori inside chaos in Hamiltonian systems (Ali, H.; Punjabi, A. Plasma Phys. Contr. F. 2007, 49, 1565-1582) is applied to the axially symmetric divertor experiment upgrade (ASDEX UG) tokamak to build noble irrational magnetic barriers inside chaos created by resonant magnetic perturbations (m, n)=(3, 2)+(4, 3), with m and n the poloidal and toroidal mode numbers of the Fourier expansion of the magnetic perturbation. The radial dependence of the Fourier modes is ignored. The modes are considered to be locked and have the same amplitude ?. A symplectic mathematical mapping in magnetic coordinates is used to integrate magnetic field line trajectories in the ASDEX UG. Tori with noble irrational rotational transform are the last ones to be destroyed by perturbation in Hamiltonian systems. For this reason, noble irrational magnetic barriers are built inside chaos, and the strongest noble irrational barrier is identified. Three candidate locations for the strongest noble barrier in ASDEX UG are selected. All three candidate locations are chosen to be roughly midway between the resonant rational surfaces ?32 and ?43. ? is the magnetic coordinate of the flux surface. The three candidate surfaces are the noble irrational surfaces close to the surface with q value that is a mediant of q=3/2 and 4/3, q value of the physical midpoint of the two resonant surfaces, and the q value of the surface where the islands of the two perturbing modes just overlap. These q values of the candidate surfaces are denoted by qMED, qMID, and qOVERLAP. The strongest noble barrier close to qMED has the continued fraction representation (CFR) [1;2,2,1?] and exists for ??2.6599×10-4; the strongest noble barrier close to qMID has CFR [1;2,2,2,1?] and exists for ??4.6311×10-4; and the strongest noble barrier close to qOVERLAP has CFR [1;2,2,6,2,1?] and exists for ??1.367770×10-4. From these results, the strongest noble barrier is found to be close to the surface that is located physically exactly in the middle of the two resonant surfaces.

  14. Underground Sources of Radioactive Noble Gas

    SciTech Connect

    Hayes, James C.; Bowyer, Ted W.; Cordova, Elsa A.; Kirkham, Randy R.; Misner, Alex C.; Olsen, Khris B.; Woods, Vincent T.; Emer, Dudley

    2013-05-01

    It is well known that radon is present in relatively high concentrations below the surface of the Earth due to natural decay of uranium and thorium. However, less information is available on the background levels of other isotopes such as 133Xe and 131mXe produced via spontaneous fission of either manmade or naturally occurring elements. The background concentrations of radioxenon in the subsurface are important to understand because these isotopes potentially can be used to confirm violations of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) during an On-Site Inspection (OSI). Recently, Pacific Northwest National Laboratory (PNNL) measured radioxenon concentrations from the subsurface at the Nevada Nuclear Security Site (NNSS—formerly known as the Nevada Test Site) to determine whether xenon isotope background levels could be detected from spontaneous fission of naturally occurring uranium or legacy 240Pu as a result of historic nuclear testing. In this paper, we discuss the results of those measurements and review the sources of xenon background that must be taken into account during OSI noble gas measurements.

  15. Noble gas paleotemperatures and water contents of stalagmites - a new extraction tool and a new paleoclimate proxy

    NASA Astrophysics Data System (ADS)

    Vogel, N.; Scheidegger, Y.; Brennwald, M. S.; Fleitmann, D.; Figura, S.; Wieler, R.; Kipfer, R.

    2012-04-01

    Stalagmites represent excellent multi-proxy paleoclimate archives as they cover long timescales and can be dated with high precision [e.g., 1]. The absolute temperature at which a stalagmite grew, can be deduced from the amounts of atmospheric noble gases dissolved in the stalagmite's fluid inclusion water (= noble gas temperature, NGT) [2-4]. We present technical advances towards more robust NGT determinations and also propose a new paleoclimate proxy, namely the stalagmite's water content, which is a "by-product" of NGT determination. Water contents and oxygen isotope records of two Holocene stalagmites from Socotra Island (Yemen) were found to vary systematically: progressively lighter oxygen is accompanied by decreasing water contents and vice versa. Via the oxygen isotope records [5] the stalagmites' water contents are linked to the amounts of precipitation on Socotra Island. High precipitation, i.e., high drip rates lead to homogeneous calcite growth with low porosity and therefore a small number of water-filled inclusions, i.e. low water contents. A reduction of drip water supply fosters irregular crystal growth with higher porosity, leading to higher water contents of the calcite (see also [6]). Therefore the stalagmites' water contents seem to record changes in drip water supply and, under favourable conditions, changes in regional precipitation. The current method to extract water and noble gases from stalagmite samples is experimentally challenging and subject to certain limitations (e.g., time-consuming sample preparation in a glove box, temperature restrictions for water extraction, and the often inadequate correction for air from residual air-filled inclusions [3, 4]). To overcome these limitations we have developed a new type of crusher directly attached to our noble gas line. It not only allows crushing and separating the samples into different grain size fractions in vacuo, but the separates can be individually heated to significantly higher temperatures than before allowing a more quantitative water extraction. Additionally, air released from air-filled inclusions can be analyzed during the crushing procedure with a new quadrupole mass spectrometer. This additional piece of information will considerably improve the above mentioned corrections resulting in more robust and accurate NGTs. [1] Henderson G.M. (2006) Science, 313, 620-622. [2] Kluge T., et al. (2008) Earth Planet. Sc. Lett., 269, 408-415. [3] Scheidegger Y.M., et al. (2010) Chem. Geol., 272, 31-39. [4] Scheidegger Y.M., et al. (2011) Chem. Geol., 288, 61-66. [5] Fleitmann D., et al. (2007) Quart. Sci. Rev., 26, 170-188. [6] Fairchild I.J., et al. (2008) Speleothems, in Geochemical sediments and landscapes, Blackwell Publishing Ltd.: Oxford, UK. 200-245.

  16. Noble Metal Nanoparticle-loaded Mesoporous Oxide Microspheres for Catalysis

    NASA Astrophysics Data System (ADS)

    Jin, Zhao

    Noble metal nanoparticles/nanocrystals have attracted much attention as catalysts due to their unique characteristics, including high surface areas and well-controlled facets, which are not often possessed by their bulk counterparts. To avoid the loss of their catalytic activities brought about by their size and shape changes during catalytic reactions, noble metal nanoparticles/nanocrystals are usually dispersed and supported finely on solid oxide supports to prevent agglomeration, nanoparticle growth, and therefore the decrease in the total surface area. Moreover, metal oxide supports can also play important roles in catalytic reactions through the synergistic interactions with loaded metal nanoparticles/nanocrystals. In this thesis, I use ultrasonic aerosol spray to produce hybrid microspheres that are composed of noble metal nanoparticles/nanocrystals embedded in mesoporous metal oxide matrices. The mesoporous metal oxide structure allows for the fast diffusion of reactants and products as well as confining and supporting noble metal nanoparticles. I will first describe my studies on noble metal-loaded mesoporous oxide microspheres as catalysts. Three types of noble metals (Au, Pt, Pd) and three types of metal oxide substrates (TiO2, ZrO2, Al 2O3) were selected, because they are widely used for practical catalytic applications involved in environmental cleaning, pollution control, petrochemical, and pharmaceutical syntheses. By considering every possible combination of the noble metals and oxide substrates, nine types of catalyst samples were produced. I characterized the structures of these catalysts, including their sizes, morphologies, crystallinity, and porosities, and their catalytic performances by using a representative reduction reaction from nitrobenzene to aminobenzene. Comparison of the catalytic results reveals the effects of the different noble metals, their incorporation amounts, and oxide substrates on the catalytic abilities. For this particular reaction, I found that Pd nanoparticles supported on mesoporous TiO2 exhibit the best catalytic performance. The demonstrated low-cost and high-productivity preparation method can be extended to other catalysts, which can contain various metals and oxide substrates and will have high potential for industrial applications. Our preparation method also provides a platform for the studies of the synergetic catalytic effects between different oxide substrates and metals. I further fabricated hollow mesoporous microspheres containing differently shaped noble metal nanocrystals. Hollow structures are strongly desired in many applications because of their high pore volumes, surface areas, and possible light-trapping effect. In my study, the hollow structures were obtained by simply dispersing polystyrene (PS) nanospheres into the precursor solution for aerosol spray. The PS spheres were removed by thermal calcination to produce hollow mesoporous microspheres. In my first study, the noble metal salts were dissolved in the precursor solutions, and the noble metal nanoparticles were obtained through thermal calcination. In this way, the size and shape of the metal nanoparticles cannot be well controlled. In my second study, I first grew noble metal nanocrystals and then incorporated them into the oxide supports. This preparation route allowed me to incorporate metal nanocrystals with controlled sizes, shapes, and compositions into the oxide matrices. The metal nanocrystals I used in this experiment included Pd nanocubes, Au nanorods, and Au core--Pd shell nanorods. These nanocrystals were functionalized with thiol-terminated methoxypoly(ethylene glycol) . The surface functionalization allowed them to adsorb on the PS spheres. After thermal calcination, the noble metal nanocrystals were left inside and adsorbed on the inner surface of the hollow mesoporous metal oxide microspheres. I investigated the catalytic activities of the Pd nanocube-embedded hollow mesoporous TiO2 and ZrO2 microspheres for the reduction of 4-nitrophenol to 4-aminophenol. I also examined the recycla

  17. Developments in Noble Gas mass spectrometry

    NASA Astrophysics Data System (ADS)

    Hamilton, D.; Schwieters, J. B.; Lloyd, N. S.

    2010-12-01

    D. HAMILTON*, J.B. SCHWIETERS, D. TUTTAS, M. KRUMMEN, M. DEERBERG, N.S. LLOYD1 1Thermo Fisher Scientific, Hanna-Kunath-Str. 11, 28199 Bremen, Germany (*correspondence: Doug.Hamilton@ThermoFisher.com) Recent advances in ion optics and electronic design have added features to the new range of Noble Gas mass spectrometers from Thermo Fisher Scientific that will enable the scientific community to resolve a number of existing analytical limitations. The first development relates to detector technology. Because instrument transmission and ion source efficiency can be very high, detector noise can be the limiting factor for ultra-small sample analysis. Faraday cup detectors are the detectors of choice for high accuracy and high precision isotope ratio measurements because of their unmatched stability and linearity and because of the electronic cross calibration network available to precisely and accurately cross calibrate the multiple Faraday detector channels against each other. Today, most IOMS systems are equipped with current amplifiers using a 1011 Ohm resistor coupled to the feedback loop of a high stability and temperature-stabilized operational amplifier. In this paper we will describe our latest investigations in Faraday cup measurements utilising 1012 & 1013 resistors for signal intensities in the range of 1 pA to 1 fA. The second development relates to a new beam deflection technology added to the ARGUS VI mass spectrometer that enables a fixed collector array to be given some of the properties of a mechanically adjustable array. This enables multidynamic multicollector measurements to be taken utilising a fixed array thus enabling the end user to perform vital detector crosscalibrations “in run”. Lastly we will describe early results on a new high resolution platform and the capabilities of this platform to finally deal with certain isotopic interferences in both the Argon and Neon spectra.

  18. (Desulfurization of fuel gases)

    SciTech Connect

    Not Available

    1991-12-15

    The objective of this work was to demonstrate that solid solutions of cerium oxide (CeO{sub 2}) and other altervalent oxides (doped CeO{sub 2}) were capable of removing more H{sub 2}S from fuel gases than Ceo{sub 2} without any dopant. The ability of undoped CeO{sub 2} to remove H{sub 2}S from fuel gases had been determined with a previous DOE/SBIR grant. To make the results obtained under the two grants comparable, the procedures for all phases of this work duplicated that used previously as closely as possible. The sorbents GDC proposed to investigate were: (1) undoped CeO{sub 2}, (2) CeO{sub 2} doped with 5 mole % (5 m/o) magnesium oxide (MgO), and (3) CeO{sub 2} doped with 5 m/o lanthanum oxide (La{sub 2}O{sub 3}). Three additional sorbents: (1) CeO{sub 2} doped with 5 m/o strontium oxide (SrO), (2) CeO{sub 2} doped with 10 m/o SrO, and (2) CeO{sub 2} doped with 10 m/o La{sub 2}O{sub 3} were also investigated. All of these sorbents were prepared using the Marcilly technique.

  19. Evaluating the accretion of meteoritic debris and interplanetary dust particles in the GPC-3 sediment core using noble gas and mineralogical tracers

    NASA Astrophysics Data System (ADS)

    Darrah, Thomas H.; Poreda, Robert J.

    2012-05-01

    Extraterrestrial (ET) noble gases (helium and neon) in 35 sediment samples from Central Pacific core LL-44 GPC-3 demonstrate the variable flux of interplanetary dust particles (IDPs) and major meteorite impacts over the past 70 Ma (21-72 Ma). Spinel mineralogical and chemical compositions clearly distinguish major impact events from the continuous flux of IDPs, including the well-established Cretaceous/Tertiary (K/T) and late Eocene (E/O) impact boundaries. No spinel grains with chemical or mineralogical evidence of a distinctly ET origin were found in an extensive survey of 'background' samples (i.e. non E/O or K/T boundary) suggesting that either the carrier grains for ET noble gas occur within the Fe-Ti oxide mineral fraction observed in this study (found to include ilmenite and ulvospinel) or are too small for identification by SEM. The presence of ilmenite and ulvospinel suggest lunar regolith is a potential source for ET noble gas-rich particles. Noble gas analysis on both the EMF (extractable magnetic fraction) and the Bulk minus EMF (Bulk - EMF) show that the He and Ne compositions are consistent with partially degassed noble gas signatures of zero-age magnetic grains (Z-MAG) and stratospheric interplanetary dust particles (IDPs). Conclusive evidence for a 'planetary' (Ne-A) noble gas signature is found only in the bulk sediments at the K/T boundary, although all GPC-3 K/T fractions (Bulk, EMF, and HF Digestion) plot along a mixing line between planetary (Ne-A) and solar wind (SW). Spinels from major impact boundaries (K/T; E/O) exhibit dendritic texture and elevated [Ni], consistent with previous reports. In contrast to the otherwise consistent [3He] signal from IDPs, the [3He] at the known impact boundaries (K/T and E/O) actually decreases. These anomalously low [3He] are accompanied by significantly elevated [Ne] and significantly lower (3He/20Ne)solar ratios (˜10× lower) produced by both preferentially degassing of He relative to Ne at times of increased flux of larger ET material. Degassed ("degassed-He/enriched-Ne profile") noble gas characteristics occur in two sample intervals that do not correspond to any known impact events (47 and 71 Ma), explained by an influx of larger particles. SEM analysis of the 47 Ma sample shows spinels with dendritic textures, but without distinctive markers of large meteorite impacts (e.g. elevated Ni). Particle size increases and degassed signatures may be caused by major bolides, micrometeorites, comet showers; or simply a flux of larger IDPs, potentially with a different source.

  20. A search for noble-gas evidence for presolar oxide grains

    NASA Technical Reports Server (NTRS)

    Lewis, Roy S.; Srinivasan, B.

    1993-01-01

    Early results from an ongoing search for isotopically distinctive noble gases as evidence for presolar oxide grains are presented. With some qualifications, we do not see such evidence in spinel rich acid residue fractions from the Allende meteorite. We remain hopeful that less abundant mineral separates may yet be fruitful. Presolar grains, micro-diamonds, silicon carbide, and graphite, were found in primitive meteorites. While the abundances of these three refractory C rich grains are low, a few hundred ppm, a few ppm, & less than 1 ppm, respectively in primitive meteorites, they are tagged with high concentrations of isotopically anomalous noble gas components, Xe-HL, KR & Xe-s and Ne-E(H), and Ne-E(L). These tags have served as tracers and allowed the development of techniques for their purification and eventual identification. One might expect similar amounts of refractory presolar oxides to have survived, but so far only three cases exist for their identification. The first two cases are individual corundum oxide grains. Huss et al. found one such grain from an Orgueil residue with an Al-26/Al-27 ratio of 8.9 x 10(exp -5), about 18 times higher than the canonical initial solar system value. The second corundum grain, from Murchison, was found by Nittler et al. to have unusual oxygen in addition to a similar Al-26/Al-27 ratio of 8.7 x 10(exp -4). The oxygen was depleted in O-18 by 22 percent and enriched in O-17 by a factor of 2. The third case is a measurement by Zinner et al. on an aggregate of fine grained spinels from a Murray residue with an O-17 enrichment and a possible O-18 depletion similar to the second grain, but much subdued. This is consistent with a few such presolar grains diluted by a much larger population of isotopically normal corundum grains and an even larger number of normal spinel grains.

  1. Aptamer functionalized noble metal particles for bioanalytical and biomedical applications

    NASA Astrophysics Data System (ADS)

    Yasun, Emir

    Noble metal particles, especially gold (Au) and silver (Ag) have been exploited in a broad range of biological applications due to their unique intrinsic features that depend on their physical appearance or optoelectronic properties, which can be tuned with the change in the size or shape of those particles. Thus, this tunability enables gold nanoparticles (AuNPs) to be used in biomedical diagnostic and therapeutical applications. In photothermal therapy applications, nanomaterials, which can absorb efficiently in NIR region, are utilized since the healthy tissue or cells can't absorb at this spectral region. Among AuNPs, gold nanorods (AuNRs) are one of the best candidates for hyperthermia therapy of cancer cells with their high absorption cross-sections and tunable absorption maxima in NIR region. When this unique optical property is combined with the specificity against cancer cells utilized by aptamer conjugations, AuNRs become to be one of the most important nanoparticles employed in both cancer cell sensing and therapy. However, one drawback of AuNRs is having the surfactant CTAB on their surface, which can cause nonspecificity and cytotoxicity. In this research, the side effects of CTAB are passivated by BSA modification, where the nonspecificity and cytotoxicity are dramatically decreased prior to the NIR treatment. Recognition of changes in the rare cancer protein abundances can lead the early diagnosis of cancer, so capturing these low abundance proteins has a great significance. In this research, firstly, aptamer conjugated AuNRs were used to capture 1ng of a-thrombin effectively from plasma samples as model system. Then both aptamer conjugated AuNRs and silver microspheres (SMSs) are used to capture the biomarker proteins of a colon cancer cell line, DLD-1. Gold and silver surfaces can easily be modified through thiolate chemistry, compared to the tedious modification steps for the magnetic particles, so more aptamer immobilization can be achieved for AuNRs and SMSs, which can increase the possibility of binding to the target protein. Furthermore, SMSs offer a novel separation method, gravitational separation owing to their heavy nature. In this way, there is no need for an external stimuli to separate the captured proteins and protein isolation can take only seconds.

  2. Origins of natural gases from marine strata in Northeastern Sichuan Basin (China) from carbon molecular moieties and isotopic data

    NASA Astrophysics Data System (ADS)

    Wang, Yunpeng; Zhao, Changyi; Wang, Hongjun; Wang, Zhaoyun; Wang, Zecheng

    2013-03-01

    To determine the origin, maturity, formation mechanism and secondary process of marine natural gases in Northeastern Sichuan area, molecular moieties and carbon isotopic data of the Carboniferous and Triassic gases have been analyzed. Typical samples of marine gas precursors including low-maturity kerogen, dispersed liquid hydrocarbons (DLHs) in source rocks, residual kerogen and oil have been examined in a closed system, and several published geochemical diagrams of gas origins have been calibrated by using laboratory data. Results show that both Carboniferous and Triassic gases in the study area have a thermogenic origin. Migration leads to stronger compositional and weak isotopic fractionation, and is path dependent. Carboniferous gases and low-H2S gases are mainly formed by secondary cracking of oil, whereas high-H2S gases are clearly related to the TSR (Thermal Sulfate Reduction) process. Gases in NE Sichuan show a mixture of heavy (13C-enriched) methane in comparison to the lower maturated ethane of Triassic gas samples, suggesting a similar source and maturity for ethane and propane of Carboniferous gases, and a mixture of heavy ethane to the propane for Triassic gases. Based on the data plotted in the diagram of Chung et al. (1988), the residual kerogen from Silurian marine shale and palaeo oil reservoirs are the main source for Carboniferous gases, and that the residual kerogen from Silurian and Permian marine rocks and Permian paleao oil reservoirs constitute the principal source of Triassic gases.

  3. Method for removing acid gases from a gaseous stream

    DOEpatents

    Gorin, Everett (San Rafael, CA); Zielke, Clyde W. (McMurray, PA)

    1981-01-01

    In a process for hydrocracking a heavy aromatic polynuclear carbonaceous feedstock containing reactive alkaline constituents to produce liquid hydrocarbon fuels boiling below about 475.degree. C. at atmospheric pressure by contacting the feedstock with hydrogen in the presence of a molten metal halide catalyst, thereafter separating a gaseous stream containing hydrogen, at least a portion of the hydrocarbon fuels and acid gases from the molten metal halide and regenerating the molten metal halide, thereby producing a purified molten metal halide stream for recycle to the hydrocracking zone, an improvement comprising; contacting the gaseous acid gas, hydrogen and hydrocarbon fuels-containing stream with the feedstock containing reactive alkaline constituents to remove acid gases from the acid gas containing stream. Optionally at least a portion of the hydrocarbon fuels are separated from gaseous stream containing hydrogen, hydrocarbon fuels and acid gases prior to contacting the gaseous stream with the feedstock.

  4. Compared optical properties of noble and transition metal-dielectric granular films

    E-print Network

    Paris-Sud XI, Université de

    249 Compared optical properties of noble and transition metal-dielectric granular films S. Berthier properties according to the nature of the metallic inclusion : noble or transition. A comparison between Au these proper- ties depend on the nature ofthe metallic inclusion in the compound : noble metal or transition

  5. Polyacrylonitrile/noble metal/SiO2 nanofibers as substrates for the amplified detection of picomolar amounts of metal ions through plasmon-enhanced fluorescence

    NASA Astrophysics Data System (ADS)

    Zhang, Han; Cao, Minhua; Wu, Wei; Xu, Haibo; Cheng, Si; Fan, Li-Juan

    2015-01-01

    Electrospun polymer/noble metal hybrid nanofibers have developed rapidly as surface-enhanced Raman scattering (SERS)-active substrates over the last few years. However, polymer/noble metal nanofibers with plasmon-enhanced fluorescence (PEF) activity have received no attention to date. Herein, we show a general and facile approach for the preparation of polyacrylonitrile (PAN)/noble metal/SiO2 nanofibrous mats with PEF activity for the first time by combining electrospinning and controlled silica coatings. These PEF-active nanofibrous mats can selectively improve the fluorescence intensity of conjugated polyelectrolytes (CPEs). Importantly, the CPE solution in the presence of a PAN/noble metal/SiO2 nanofibrous mat showed dramatic fluorescence quenching towards picomolar (pM) amounts of heavy metal ions, while the fluorescence of the CPE solution without the nanofibrous mat had no apparent quenching towards micromolar (?M) amounts of metal ions. The combination of the distance-dependent fluorescence enhancement performance of metal NPs and the ionic characteristics of the CPE solution makes the polymer/noble metal nanofibers promising substrates for greatly improving the detection sensitivity towards metal ions. We believe that this work provides a general strategy for preparing plasmon band-tuned PEF-active substrates with advantages including good selectivity, remarkable sensitivity and recyclability, which make them a preferable choice for practical sensing applications.Electrospun polymer/noble metal hybrid nanofibers have developed rapidly as surface-enhanced Raman scattering (SERS)-active substrates over the last few years. However, polymer/noble metal nanofibers with plasmon-enhanced fluorescence (PEF) activity have received no attention to date. Herein, we show a general and facile approach for the preparation of polyacrylonitrile (PAN)/noble metal/SiO2 nanofibrous mats with PEF activity for the first time by combining electrospinning and controlled silica coatings. These PEF-active nanofibrous mats can selectively improve the fluorescence intensity of conjugated polyelectrolytes (CPEs). Importantly, the CPE solution in the presence of a PAN/noble metal/SiO2 nanofibrous mat showed dramatic fluorescence quenching towards picomolar (pM) amounts of heavy metal ions, while the fluorescence of the CPE solution without the nanofibrous mat had no apparent quenching towards micromolar (?M) amounts of metal ions. The combination of the distance-dependent fluorescence enhancement performance of metal NPs and the ionic characteristics of the CPE solution makes the polymer/noble metal nanofibers promising substrates for greatly improving the detection sensitivity towards metal ions. We believe that this work provides a general strategy for preparing plasmon band-tuned PEF-active substrates with advantages including good selectivity, remarkable sensitivity and recyclability, which make them a preferable choice for practical sensing applications. Electronic supplementary information (ESI) available: TEM and SEM images of PAN/Ag/SiO2 nanofibers with different thicknesses; molecular structures and fluorescence spectra of five dyes; normalized extinction spectra of PAN/Ag0.8Au0.2/SiO2 nanofibrous mats; photos of the PAN/Ag/SiO2 nanofibrous mat. See DOI: 10.1039/c4nr05349d

  6. Optical properties of noble metal nanoparticle arrays

    NASA Astrophysics Data System (ADS)

    Luo, Wei

    Optical properties of noble nanoparticle arrays are studied by surface enhanced spectroscopies. The experiments and results are reported in this thesis. Arrays of linear, size-controllable, one-dimensional (1D) silver nanoparticle rows have been prepared that demonstrate exceptional surface-enhanced Raman scattering (SERS) from incident light polarized along the axis of the arrays. These 1D rows were prepared by physical vapor deposition (PVD) of silver (˜ 0.25 angstrom/s) at an equivalent uniform film thickness of 2-7 nm onto highly oriented pyrolytic graphite (HOPG) surfaces at 400 °C. At these elevated temperatures, atomically deposited silver has a sufficiently high surface mobility to reorder into nanoparticles that associate to the graphite step edges. Both the average 15-60 nm nanoparticle sizes and 7-20 nm gaps between adjacent particles within the rows were controlled by the overall silver evaporation thickness. The rows were typically hundreds of microns long with 10-1000 nm spacing between adjacent 1D rows that correspond to the space between the graphite step edge spacing. Similar 1D gold and silver/gold hybrid nanoparticle rows have been prepared using the same method. The polarization dependence and the enhancement of the Raman scattered light was characterized using a monolayer of adsorbed thiophenol on the silver nanoparticle surfaces as Raman probe molecules. To understand this polarization selectivity, electromagnetic calculations modeled the response of the interacting nanoparticles with an incident light field, and the influence of particle size and gap spacing in the one dimensional arrays. Modeled Raman enhancement factors show consistency with the experimental results. Following the PVD growth of Ag or Au nanoparticle arrays on HOPG surfaces, we electrochemically deposit cadmium around these nanoparticle arrays to form hybrid nanowires as thin as 50-60 nm in width. Further annealing of these hybrid nanowires in H2S at temperatures of 300-320 °C enables the formation of CdS nanowires around the Ag or Au nanoparticle cores. Using this combined PVD/electrochemistry/chemical modification approach we have been able to generate ordered 2-D arrays of hybrid semiconductor nanowires that are as small as 100 nm in diameter and 100s of microns in length. Under light illumination, the surface plasmon supported by the Ag or Au nanoparticle cores enhances the photoluminescence of the outer CdS nanowires.

  7. Biomimetic synthesis of noble metal nanocrystals

    NASA Astrophysics Data System (ADS)

    Chiu, Chin-Yi

    At the nanometer scale, the physical and chemical properties of materials heavily depend on their sizes and shapes. This fact has triggered considerable efforts in developing controllable nanomaterial synthesis. The controlled growth of colloidal nanocrystal is a kinetic process, in which high-energy facets grow faster and then vanish, leading to a nanocrystal enclosed by low-energy facets. Identifying a surfactant that can selectively bind to a particular crystal facet and thus lower its surface energy, is critical and challenging in shape controlled synthesis of nanocrystals. Biomolecules exhibiting exquisite molecular recognition properties can be exploited to precisely engineer nanostructured materials. In the first part of my thesis, we employed the phage display technique to select a specific multifunctional peptide sequence which can bind on Pd surface and mediate Pd crystal nucleation and growth, achieving size controlled synthesis of Pd nanocrystals in aqueous solution. We further demonstrated a rational biomimetic approach to the predictable synthesis of nanocrystals enclosed by a particular facet in the case of Pt. Specifically, Pt {100} and Pt {111} facet-specific peptides were identified and used to synthesize Pt nanocubes and Pt nano-tetrahedrons, respectively. The mechanistic studies of Pt {111} facet-specific peptide had led us to study the facet-selective adsorption of aromatic molecules on noble metal surfaces. The discoveries had achieved the development of design strategies to select facet-selective molecules which can synthesize nanocrystals with expected shapes in both Pt and Pd system. At last, we exploited Pt facet-specific peptides and controlled the molecular interaction to produce one- and three- dimensional nanostructures composed of anisotropic nanoparticles in synthetic conditions without supramolecular pre-organization, demonstrating the full potential of biomolecules in mediating material formation process. My research on biomimetic synthesis of nanocrystals with shape control and nanostructures with control over the anisotropy are unprecedented, representing a step forward in achieving the goal of producing complex nanostructures with required properties. The fundamental studies on the biomolecule-inorganic interfaces have contributed to advancing the synthesis tool of colloidal nanomaterials and enriching understating of organic-inorganic interface, impacting many applications.

  8. Kinetic Molecular Theory of Gases

    NSDL National Science Digital Library

    David N. Blauch

    Applets dealing with the meaning of the Maxwell distribution of gases and pressure of gases are discussed. The Maxwell distribution experiment allow the user to explore the most probable speed of gas molecules. The pressure experiment allows the user to explore the effects of size and mass on collision rate, direction, and relative speed of gas molecules within a fixed volume.

  9. Greenhouse Gases: A Closer Look

    NSDL National Science Digital Library

    King's Centre for Visualization in Science

    This lesson covers different aspects of the major greenhouse gases - water vapor, carbon dioxide, methane, nitrous oxides and CFCs - including some of the ways in which human activities are affecting the atmospheric concentrations of these key greenhouse gases. This is lesson six in a nine-lesson module about climate change.

  10. Shock Waves in Granular Gases

    Microsoft Academic Search

    Alexander Goldshtein; Alexander Alexeev; Michael Shapiro

    2003-01-01

    This review is the first attempt to systematize the results on shock waves in granular gases. We present experimental and computational evidences of shock and expansion waves propagating within granular gases. The analysis of model flows with shock and expansion waves shows that even smallest kinetic energy dissipations crucially affects such flows. We discuss the role of these waves for

  11. Voluntary Reporting of Greenhouse Gases

    EIA Publications

    2011-01-01

    The Voluntary Reporting of Greenhouse Gases Program was suspended May 2011. It was a mechanism by which corporations, government agencies, individuals, voluntary organizations, etc., could report to the Energy Information Administration, any actions taken that have or are expected to reduce/avoid emissions of greenhouse gases or sequester carbon.

  12. Comparison of various stopping gases for 3He-based position sensitive neutron detectors

    NASA Astrophysics Data System (ADS)

    Doumas, A.; Smith, G. C.

    2012-05-01

    A range of solid state, scintillator and gas based detectors are being developed for use at the next generation of high flux neutron facilities. Since gas detectors are expected to continue to play a key role in future specific thermal neutron experiments, a comparison of the performance characteristics of prospective stopping gases is beneficial. Gas detectors typically utilize the reaction 3He(n,p)t to detect thermal neutrons; the 3He gas is used in a mixture containing a particular stopping gas in order to maintain relatively short ranges for the proton and triton pair emitted from the n-3He reaction. Common stopping gases include hydrocarbons (e.g. propane), carbon tetrafluoride, and noble gases such as argon and xenon. For this study, we utilized the Monte Carlo simulation code "Stopping and Range of Ions in Matter" to analyze the expected behavior of argon, xenon, carbon dioxide, difluoroethane and octafluoropropane as stopping gases for thermal neutron detectors. We also compare these findings to our previously analyzed performance of propane, butane and carbon tetrafluoride. A discussion of these gases includes their behavior in terms of proton and triton range, ionization distribution and straggle.

  13. Synthesis and characterization of fluorescence-labelled silica core-shell and noble metal-decorated ceria nanoparticles

    PubMed Central

    Rennhak, Markus; Reller, Armin

    2014-01-01

    Summary The present review article covers work done in the cluster NPBIOMEM in the DFG priority programme SPP 1313 and focuses on synthesis and characterization of fluorescent silica and ceria nanoparticles. Synthetic methods for labelling of silica and polyorganosiloxane/silica core–shell nanoparticles with perylenediimide derivatives are described, as well as the modification of the shell with thiol groups. Photometric methods for the determination of the number of thiol groups and an estimate for the number of fluorescent molecules per nanoparticles, including a scattering correction, have been developed. Ceria nanoparticles decorated with noble metals (Pt, Pd, Rh) are models for the decomposition products of automobile catalytic converters which appear in the exhaust gases and finally interact with biological systems including humans. The control of the degree of agglomeration of small ceria nanoparticles is the basis for their synthesis. Almost monodisperse agglomerates (40 ± 4–260 ± 40 nm diameter) can be prepared and decorated with noble metal nanoparticles (2–5 nm diameter). Fluorescence labelling with ATTO 647N gave the model particles which are now under biophysical investigation. PMID:25671137

  14. Synthesis and characterization of fluorescence-labelled silica core-shell and noble metal-decorated ceria nanoparticles.

    PubMed

    Herrmann, Rudolf; Rennhak, Markus; Reller, Armin

    2014-01-01

    The present review article covers work done in the cluster NPBIOMEM in the DFG priority programme SPP 1313 and focuses on synthesis and characterization of fluorescent silica and ceria nanoparticles. Synthetic methods for labelling of silica and polyorganosiloxane/silica core-shell nanoparticles with perylenediimide derivatives are described, as well as the modification of the shell with thiol groups. Photometric methods for the determination of the number of thiol groups and an estimate for the number of fluorescent molecules per nanoparticles, including a scattering correction, have been developed. Ceria nanoparticles decorated with noble metals (Pt, Pd, Rh) are models for the decomposition products of automobile catalytic converters which appear in the exhaust gases and finally interact with biological systems including humans. The control of the degree of agglomeration of small ceria nanoparticles is the basis for their synthesis. Almost monodisperse agglomerates (40 ± 4-260 ± 40 nm diameter) can be prepared and decorated with noble metal nanoparticles (2-5 nm diameter). Fluorescence labelling with ATTO 647N gave the model particles which are now under biophysical investigation. PMID:25671137

  15. 46 CFR 194.15-17 - Compressed gases other than inert gases.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Compressed gases other than inert gases. 194.15-17 Section 194...AND OTHER HAZARDOUS MATERIALS Chemistry Laboratory and Scientific Laboratory § 194.15-17 Compressed gases other than inert gases....

  16. 46 CFR 194.15-17 - Compressed gases other than inert gases.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Compressed gases other than inert gases. 194.15-17 Section 194...AND OTHER HAZARDOUS MATERIALS Chemistry Laboratory and Scientific Laboratory § 194.15-17 Compressed gases other than inert gases....

  17. 46 CFR 194.15-17 - Compressed gases other than inert gases.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Compressed gases other than inert gases. 194.15-17 Section 194...AND OTHER HAZARDOUS MATERIALS Chemistry Laboratory and Scientific Laboratory § 194.15-17 Compressed gases other than inert gases....

  18. Measuring the noble metal and iodine composition of extracted noble metal phase from spent nuclear fuel using instrumental neutron activation analysis.

    PubMed

    Palomares, R I; Dayman, K J; Landsberger, S; Biegalski, S R; Soderquist, C Z; Casella, A J; Brady Raap, M C; Schwantes, J M

    2015-04-01

    Masses of noble metal and iodine nuclides in the metallic noble metal phase extracted from spent fuel are measured using instrumental neutron activation analysis. Nuclide presence is predicted using fission yield analysis, and radionuclides are identified and the masses quantified using neutron activation analysis. The nuclide compositions of noble metal phase derived from two dissolution methods, UO2 fuel dissolved in nitric acid and UO2 fuel dissolved in ammonium-carbonate and hydrogen-peroxide solution, are compared. PMID:25644079

  19. High-Precision Noble Gas Analysis of Allende Diamond

    NASA Astrophysics Data System (ADS)

    Brazzle, R. H.; Gao, X.; Hohenberg, C. M.; Nichols, R. H., Jr.

    1993-07-01

    We have performed a high-resolution step-wise pyrolysis experiment (29 temperature steps from 600 degrees C to 2100 degrees C) on a 1.625 mg sample of diamond (is identical to C delta) residue from Allende (CV3) prepared at Washington University. Our initial motivation for this work was to determine, by utilizing a relatively large number of release fractions, whether any of the Xe components previously observed in meteoritic C delta residues (e.g., Xe-P3, Xe-HL is identical to Xe-Ex, Xe-Y [1-4]) could be better resolved. In particular, we wanted to determine whether any temperature-dependent separation of Xe-H from Xe-L could be observed (as has been noted by [2]). However, as expected on a priori grounds [e.g. 4], such a separation was not observed, and the Ne, Ar, Kr, and Xe analyses of this work are consistent, within error, with previous noble gas analyses of meteoritic diamond [1-4]. The Xe data (Fig. 1) show the three-component mixing seen in earlier works [1-4]. The inferred Xe-Ex endmember composition is in good agreement with the results of [4], which utilized a larger suite of meteorites. The inferred limits on the possible endmember compositions of the Xe-Y component, however, are somewhat different from those derived in [4] (See Fig. 1). The Ar data show a similar three-component mixing (Ar-P3, Ar-Ex, Ar-Y; cf. [4]), and we obtain the following limits for ^38Ar/^36Ar in the latter two components: (^38Ar/^36Ar)(sub)Ex > 0.2220 and (^38Ar/^36Ar)(sub)Y < 0.2088. In addition, our data indicate that (Ar/Xe)(sub)P3>(Ar/Xe)(sub)Y>(Ar/Xe)(sub)Ex, consistent with the results of [4]. The Ne data clearly indicate the presence of at least two components: Ne-P3 and Ne-A2. On a standard Ne three- isotope plot the Ne data lie within ~2 sigma of a line connecting the points (20:21:22) = (8.45:0.032:1.00) and = (7.65:0.41:1.00). Although Ne-A2 may possibly represent a mix between a Ne-Ex and a Ne-Y component [4], we cannot resolve Ne-Ex from Ne-Y, neither on the basis of the Ne isotopes alone nor by relying on the elemental abundances of these components for Ar and Xe. Contributions from a Ne-E-like component and spallogenic Ne may be required to explain the data. However, such contributions are probably not indigenous to the diamonds, but may be due to minor contaminant phases or to gases inherited from phases dissolved during processing. We also observe clear excesses of spallogenic and halogen-derived (from neutron captures) Ar, Kr, and Xe in the lower temperature fractions. Again, these components are probably not indigenous to the diamonds, but were presumably acquired by the diamonds from other phases during processing or via implantation from spallation recoils during Allende's recent cosmic ray exposure. Similar neutron effects occurring during Allende's recent exposure have been observed by [5] and larger neutron effects were observed in an Inman residue of lesser purity [2]. References. [1] Lewis R. S. and Anders E. (1988) LPS XIX, 679- 680. [2] Nichols R. H. Jr. et al. (1991) GCA, 55, 2921-2936. [3] Verchovsky et al. (1993) LPS XXIII, 1467-1468. [4] Huss G. R. and Lewis R. S. (1993) Meteoritics, submitted. [5] Gobel R. et al. (1992) GCA 46, 1777-1792.

  20. WORK WITH A NOBLE GAS SCINTILLATION COUNTER (thesis)

    Microsoft Academic Search

    1958-01-01

    Submitted to United States Naval Postgraduate School Monterey, Calif. ; More than 1450 runs were made and analyzed with a noble gas scintillation counter ; and its associated equip ment. The counter itself consists of a special ; photomultiplier tube looking into a scintillation chamber, and is used in ; conjunction with a vacuum and filling system, an output-pulse amplification

  1. The Origin of Noble Gas Isotopic Heterogeneity in Icelandic Basalts

    NASA Technical Reports Server (NTRS)

    Dixon, E. T.; Honda, M.; McDougall, I.

    2001-01-01

    Two models for generation of heterogeneous He, Ne and Ar isotopic ratios in Icelandic basalts are evaluated using a mixing model and the observed noble gas elemental ratios in Icelandic basalts,Ocean island Basalt (OIBs) and Mid-Ocean Ridge Basalt (MORBs). Additional information is contained in the original extended abstract.

  2. Methanol transformations. Supported noble metal chlorides as catalysts

    Microsoft Academic Search

    M. Marczewski; A. Krzywicki; M. Pawula

    1983-01-01

    Transformations of methanol over supperted noble metal chlorides have been studied. The fastest reaction of methanol at 573 K is the decomposition to H2 and CO. Hydrocarbons formed during the reaction are products of secondary reactions between CO and H2.

  3. Noble gas component organization in Apollo 14 breccia 14318: /sup 129/I and /sup 244/Pu regolith chronology

    SciTech Connect

    Swindle, T.D.; Caffee, M.W.; Hohenberg, C.M.; Hudson, G.B.; Laul, J.C.; Simon, S.B.; Papike, J.J.

    1985-02-15

    Noble gas, petrological, and chemical studies made on grain-size separates from lunar regolith breccia 14318 demonstrate that the noble gases are organized into two functional components, volume-correlated and surface-correlated. As in regolith breccia 14301, volume-correlated xenon in 14318 is primarily spallation-derived and the surface-correlated component contains not only solar wind xenon but also significant amounts of ''parentless' xenon from the fission of now extinct /sup 244/Pu and the decay of now extinct /sup 129/I (''parentless'' means the daughter products were incorporated onto grain surfaces following decay of the parent nuclide elsewhere). The ratio of /sup 129/Xe//sup 136/Xe in the total surface-correlated parentless component, as identified in grain-size analysis, is substantially higher than in the least tightly bound parentless component identified in stepwise heating analyses, confirming the trend seen in 14301. If the order of release of gases in stepwise heating is related to the order of incorporation in the simplest way (first in, last out), incorporation of these grain-surface components was probably time-ordered. The /sup 129/Xe//sup 136/Xe ratio in each identifiable parentless component would then be characteristic of the xenon available for surface adsorption at the particular time of acquisition. Continuous variations in this ratio further suggest that incorporation of the parentless xenon was closely coupled with production. Such observations provide the basis for a new chronometer from which we conclude that acquisition of parentless xenon was an ongoing process spanning at least 90 m.y., beginning no more than 44 +- 34 m.y. after the formation of the most meteorites and possibly predating xenon acquisition for the earth.

  4. Field Enhancement using Noble Metal Structures

    NASA Astrophysics Data System (ADS)

    Liu, Benliang

    Resonance may be one of the most fundamental rules of nature. Electromagnetic resonance at nanometer scale could produce a giant field enhancement at optical frequency, providing a way to measure and control the process of atoms and molecules at single molecule scale. For example, the giant field enhancement would provide single molecule sensitivity for Raman scattering, which provides unique tools in measuring the quantity in extremely low concentration. In addition, light-emitting diodes could have high brightness but low input power that would be revolutionary in the optoelectronic industry. Although light enhancement is promising in several key technology areas, there are several challenges remain to be tackled. In particular, since the field enhancement is so strongly geometry dependent that slight modification of the geometry can lead to large variations in the outcome, a thorough understanding in how the geometry of the structure affects the field enhancement and creating proper methods to fabricate these structures reproducibly is of most importance. This thesis is devoted to design, fabrication and characterization of field enhancement generated on the surface of noble metals such as silver or gold with 1D structure. The s-polarized field enhancement arising from one-dimensional metal gratings is designed and optimized by using Rigorous Coupling Wave Analysis (RCWA). After optimization, the strongest enhancement factor is found to be 9.7 for 514nm wavelength light. The theoretical results arc confirmed by angle-dependent reflectivity measurements and the experimental results are found to support the theory. A novel single slit structure employing surface plasmon polaritons (SPPs) for enhancing the electric field is studied. SPPs are first generated on a 50 nm thick metal film using attenuated total reflection coupling, and they are subsequently coupled to the cavity mode induced by the single slit. As a result, the field enhancement is found at least 3 times the surface plasmon background adjacent to the slit, as predicted by using RCWA. The mechanism for enhancement is theoretically studied both numerically and analytically. Two novel convenient methods for fabricating nanoslits with high aspect ratio are proposed. One is creating nanoslits by cracking the thin glass substrates with metal film. Sub-5nm wide slits with fair uniformity are created, as confirmed by Scanning Electron Microscopy images and comparing the Confocal Two Photon Emission (CTPE) spectroscopy with finite difference in time domain simulations. The other is creating slits by fatiguing the metal film on a flexible substrate. Enhanced CTPE and second harmonic generation are observed arising from these less than 20nm wide slits. Nanoslits fabricated using Electron Beam Lithography (EBL) are characterized using CTPE. The overall emission enhancement of excitation and collection wavelengths is separated by a proposed method. It is surprisingly found that the pulsing laser can tune the resonant wavelength of the EBL samples to the laser wavelength. A mechanism is proposed for this phenomenon. It is shown this can be developed into a tool to fabricate field enhancement hot spots.

  5. Chemistry of free and dissolved gases of Matupit Bay, Rabaul caldera, Papua New Guinea

    Microsoft Academic Search

    A. I. Obzhirov

    1992-01-01

    Free gases from fumaroles of the Tavurvur and Rabalanakaia volcanoes are liberated as bubbles from the seafloor of Matupit Bay. The free gases contain methane (as high as 0.02%), heavy hydrocarbons (0.00001–0.0004%), carbon dioxide (more than 90%), and hydrogen sulfide (up to 27.9%). Background levels of dissolved methane are 30–50 nl\\/liter; they become seven times higher in the area of

  6. Investigating and Using Biomass Gases

    NSDL National Science Digital Library

    2012-07-03

    In this activity, learners will be introduced to biomass gasification and will generate their own biomass gases. Learners generate these gases everyday on their own and find it quite amusing, but this time they’ll do it by heating wood pellets or wood splints in a test tube. They will collect the resulting gases and use the gas to roast a marshmallow. Learners will also evaluate which biomass fuel is the best either according to their own criteria or by examining the volume of gas produced by each type of fuel.

  7. Environmental implications of anesthetic gases.

    PubMed

    Yasny, Jeffrey S; White, Jennifer

    2012-01-01

    For several decades, anesthetic gases have greatly enhanced the comfort and outcome for patients during surgery. The benefits of these agents have heavily outweighed the risks. In recent years, the attention towards their overall contribution to global climate change and the environment has increased. Anesthesia providers have a responsibility to minimize unnecessary atmospheric pollution by utilizing techniques that can lessen any adverse effects of these gases on the environment. Moreover, health care facilities that use anesthetic gases are accountable for ensuring that all anesthesia equipment, including the scavenging system, is effective and routinely maintained. Implementing preventive practices and simple strategies can promote the safest and most healthy environment. PMID:23241038

  8. Noble gas and carbon isotopes in natural gas: a new methodology for oil and gas exploration/production

    NASA Astrophysics Data System (ADS)

    Prinzhofer, A.; Battani, A.

    2003-04-01

    Isotopic measurements of both stables isotopes and noble gases give important clues to reconstruct the geological history of hydrocarbons, from their generation to their accumulation. Recent analytical advances in carbon isotopes of natural gases (methane to butane and carbon dioxide) allowed to characterize some of the physico-chemical processes which affect natural gas, instead of using these signatures as simple fingerprinting of origins as it was the case some decades ago. These reconstructions provide important information on both the origins and the dynamic behavior of hydrocarbon fluids in sedimentary basins. Moreover, correlating this methodology with other natural tracers increases the knowledge of hydrocarbon history. Among them, noble gas isotopes may be the new frontier tool, as their chemical inertness allows to use them as precise tracers of sources and of associated physical processes (phases behavior, migration and leakage). Moreover, because some isotopes are produced by natural radioactivity, they act therefore as geological clocks, giving potentially a quantification of the residence times of hydrocarbons in a reservoir. The parameters one would hope to constrain, and which may be used as boundary conditions for basin modeling, are the age and the residence time of the fluids constituting a petroleum system, the quantitative estimate of the distance of migration of the hydrocarbons from the source rock to the reservoir and from the petroleum system to the atmosphere, and the proportion of hydrocarbons lost through leakage from the time of accumulation to the present. Other parameters associated with hydrocarbon accumulations, and more conventionally studied, include the relations between source rocks and accumulated fluids, the possible bacterial contribution through methanogenesis and/or biodegradation, the range of maturity of the fluids, the possible dysmigration of the gas from a liquid through evaporative fractionation, the characterization of permeability barriers in reservoirs, and the efficiency of accumulation. New geological case studies demonstrate the power of this new methodology, as it is possible in some cases to quantify the absolute amount of hydrocarbons lost through leakage and the relative residence times of fluids in an accumulation for an homogeneous geological setting. Diagnosis on the genesis of hydrocarbons (bacterial activity versus thermal degradation of organic matter) and on the distance of migration from the source rocks to the accumulation are also confirmed combining both stable isotopes and noble gas natural tracing.

  9. The Role of Boron-Chloride and Noble Gas Isotope Ratios in TVZ Geothermal Systems

    SciTech Connect

    Hulston, J.R.

    1995-01-01

    The model of the geothermal system in which deep circulating groundwater containing noble gases, at air saturated water concentrations, mixes with hot fluids of mantle origin at depth, is extended to include the effect of interaction of the ascending fluid with both solid and gaseous phases of basement (or other) rocks en route to the surface. It is demonstrated that this interaction is responsible for most of the CO{sub 2} in the Taupo Volcanic Zone (TVZ) geothermal systems. It is proposed that the modeling of this interaction might be accomplished by techniques similar to those used for the understanding of the oxygen isotope shift found in geothermal systems. The water rock interaction experiments of Ellis and Mahon (1964, 1967) provides some data on the kinetic rates for B and Cl dissolution from rocks likely to be encountered in the geothermal system, but further information on the behavior of B may be needed. If these problems can be overcome this modeling technique has promise for the estimation of the recharge of geothermal systems and hence the sustainability of these systems.

  10. New evidence for chondritic lunar water from combined D/H and noble gas analyses of single Apollo 17 volcanic glasses

    NASA Astrophysics Data System (ADS)

    Füri, Evelyn; Deloule, Etienne; Gurenko, Andrey; Marty, Bernard

    2014-02-01

    In order to assess the proportion of solar, cosmogenic, and indigenous water (hydrogen) trapped in individual Ti-rich lunar volcanic glasses (LVGs) from the 74002 core obtained during the Apollo 17 mission, we coupled ion microprobe measurements of water abundances and D/H ratios with CO2 laser extraction-static mass spectrometry analyses of noble gases (He, Ne, Ar). The large (?300-400 ?m in diameter) LVGs studied here contain a small amount of solar wind (SW) volatiles implanted at the grain surfaces, as indicated by the small concentrations of solar helium and neon that represent ?5% of the respective total noble gas abundances. The large proportion of volume-correlated cosmogenic gases reflects an exposure duration of ?28 Ma, on average, of the glasses at the lunar surface. Hydrogen abundances determined in the grain interiors of glassy and partially-crystalline LVGs are equivalent to between 6.5 and 54.3 ppm H2O. Based on the noble gas exposure ages, the correction of the measured hydrogen isotope composition for in situ production of cosmogenic deuterium by spallation reactions varies between -5‰ to -254‰ for the different grains. Corrected ?D values range from +38‰ to +809‰ in the LVGs and are anti-correlated with the water content, consistent with extensive hydrogen isotope fractionation during kinetic H2 loss from a lunar melt with an inferred initial isotope signature of the order of -100‰ and a water content of 100-300 ppm. The detection of water in these primitive lunar melts confirms the presence of a non-anhydrous mantle reservoir within the Moon. Furthermore, our results reveal that the hydrogen isotope composition of water in the melt source of the 74002 LVGs is similar to that of carbonaceous chondrites. These observations indicate that the contribution of deuterium-enriched cometary water to the Earth-Moon system is negligible.

  11. Low-dimensional trapped gases

    Microsoft Academic Search

    D. S. Petrov D. M. Gangardt G. V. Shlyapnikov; D. M. Gangardt; G. V. Shlyapnikov

    2004-01-01

    Recent developments in the physics of ultracold gases provide wide possibilities for reducing the dimensionality of space for magnetically or optically trapped atoms. The goal of these lectures is to show that regimes of quantum degeneracy in two-dimensional (2D) and one-dimensional (1D) trapped gases are drastically different from those in three dimensions and to stimulate an interest in low-dimensional systems.

  12. REMOVAL OF SLIGHTLY HEAVY GASES FROM A VALLEY BY CROSSWINDS

    EPA Science Inventory

    Wind-tunnel experiments made to determine how rapidly dense gas is removed from a topographical depression by a crosswind are reported. he density and flow rate of the gas (input at the bottom of a V-shaped valley in otherwise homogeneous, flat terrain)were together sufficiently ...

  13. Noble Gas Excimer Detectors for Security and Safeguards Applications

    NASA Astrophysics Data System (ADS)

    Hynes, Michael V.; Chandra, Rico; Davatz, Giovanna; Lanza, Richard

    2011-12-01

    Noble gas excimer detectors are a technology that is common in particle physics research and less common in applications for security and international safeguards. These detectors offer the capability to detect gammas with an energy resolution similar to NaI and to detect neutrons with good energy resolution as well. Depending on the noble gas selected and whether or not it is in a gaseous or liquid state, the sensitivity to gammas and neutrons can be tuned according to the needs of the application. All of this flexibility can be available at a significant cost saving over alternative technologies. This paper will review this detector technology and its applicability to security and safeguards.

  14. STM studies of 1-D noble metal growth on silicon.

    PubMed

    Baski, A A; Jones, K M; Saoud, K M

    2001-01-01

    Our scanning tunneling microscopy (STM) studies show that noble metals (Ag, Au) form a wide variety of 1-D structures on the high-index Si(5 5 12) surface. At coverages below 0.25 monolayer (ML), both metals grow as overlayer rows with an inter-row spacing of approximately 5 nm. At higher coverages and annealing temperatures, the underlying Si reconstruction is removed, but periodic row structures persist. Au can also induce faceting to nearby planes, e.g. (7 7 15) and (2 2 5), at temperatures above 500 degrees C. For all coverages and annealing temperatures studied here (0.02-1 ML, 450-800 degrees C), the Si(5 5 12) template initiates 1-D growth of the deposited noble metals. PMID:11215627

  15. Method for low temperature preparation of a noble metal alloy

    DOEpatents

    Even, Jr., William R. (Livermore, CA)

    2002-01-01

    A method for producing fine, essentially contamination free, noble metal alloys is disclosed. The alloys comprise particles in a size range of 5 to 500 nm. The method comprises 1. A method for preparing a noble metal alloy at low temperature, the method comprising the steps of forming solution of organometallic compounds by dissolving the compounds into a quantity of a compatible solvent medium capable of solvating the organometallic, mixing a portion of each solution to provide a desired molarity ratio of ions in the mixed solution, adding a support material, rapidly quenching droplets of the mixed solution to initiate a solute-solvent phase separation as the solvent freezes, removing said liquid cryogen, collecting and freezing drying the frozen droplets to produce a dry powder, and finally reducing the powder to a metal by flowing dry hydrogen over the powder while warming the powder to a temperature of about 150.degree. C.

  16. Effect of noble gas doping in single-bubble sonoluminescence

    SciTech Connect

    Hiller, R.; Weninger, K.; Putterman, S.J.; Barber, B.P. [Univ. of California, Los Angeles, CA (United States)

    1994-10-14

    The trillionfold concentration of sound energy by a trapped gas bubble, so as to emit picosecond flashes of ultraviolet light, is found to be extremely sensitive to doping with a noble gas. Increasing the noble gas content of a nitrogen bubble to about 1% dramatically stabilizes the bubble motion and increases the light emission by over an order of magnitude to a value that exceeds the sonoluminescence of either gas alone. The spectrum also strongly depends on the nature of the gas inside the bubble: Xenon yields a spectral peak at about 300 nanometers, whereas the helium spectrum is so strongly ultraviolet that its peak is obscured by the cutoff of water. 18 refs., 5 figs.

  17. Identification of potential protein markers of noble rot infected grapes.

    PubMed

    Lorenzini, Marilinda; Millioni, Renato; Franchin, Cinzia; Zapparoli, Giacomo; Arrigoni, Giorgio; Simonato, Barbara

    2015-07-15

    The evaluation of Botrytis cinerea as noble rot on withered grapes is of great importance to predict the wine sensory/organoleptic properties and to manage the winemaking process of Amarone, a passito dry red wine. This report describes the first proteomic analysis of grapes infected by noble rot under withering conditions to identify possible markers of fungal infection. 2-D gel electrophoresis revealed that protein profiles of infected and not infected grape samples are significantly different in terms of number of spots and relative abundance. Protein identification by MS analysis allowed to identify only in infected berries proteins of B. cinerea that represent potential markers of the presence of the fungus in the withered grapes. PMID:25722151

  18. Counting Rare Noble Gas Atoms with a MOT

    NASA Astrophysics Data System (ADS)

    Lu, Z.-T.; Lin, D. J.; Bailey, K.; Young, L.

    1998-05-01

    Trace analysis of certain noble gas isotopes, including krypton-81 (half-life = 230 kyr, isotope abundance = 10-12), has long been recognized to have important potential environmental and geological applications. It has motivated many developments using various techniques that include the accelerator mass spectrometry and resonance ionization spectrometry. However, signal contamination from the atoms of isobars or isotopes has been a difficult problem for the existing techniques. Taking a new approach, we are building a magneto-optical trap(MOT) of metastable noble gas atoms, with the goal of developing it into a practical device to count these atoms of rare isotopes and measure their concentrations in gas samples. The high selectivity and sensitivity of a MOT provides advantages in solving the problem of isotope contamination. This work is supported by the U.S. Department of Energy Nuclear Physics Division under contract W-31-109-ENG-38.

  19. Greenhouse gases emission from soil contaminated with automobile industry residue in Brazil

    Microsoft Academic Search

    Roberta Corrêa Nogueirol; Luís Reynaldo Ferracciú Alleoni; Felipe José Cury Fracetto; Dilmar Baretta; Carlos Eduardo Pellegrino Cerri

    2010-01-01

    Solid waste of the automobile industry containing large amounts of heavy metals might affect the emission of greenhouse gases\\u000a (GHG) when applied to the soil. Accumulation of inorganic chemical elements in the environment generally occurs due to human\\u000a activity (industry, agriculture, mining and waste landfills). Residues from human activities may release heavy metals to the\\u000a soil solution, causing toxicity to

  20. Low-field MRI of laser polarized noble gas

    NASA Technical Reports Server (NTRS)

    Tseng, C. H.; Wong, G. P.; Pomeroy, V. R.; Mair, R. W.; Hinton, D. P.; Hoffmann, D.; Stoner, R. E.; Hersman, F. W.; Cory, D. G.; Walsworth, R. L.

    1998-01-01

    NMR images of laser polarized 3He gas were obtained at 21 G using a simple, homebuilt instrument. At such low fields magnetic resonance imaging (MRI) of thermally polarized samples (e.g., water) is not practical. Low-field noble gas MRI has novel scientific, engineering, and medical applications. Examples include portable systems for diagnosis of lung disease, as well as imaging of voids in porous media and within metallic systems.

  1. Phototransformation of alkanethiol-derivatized noble metal nanoparticles

    Microsoft Academic Search

    Chil Seong Ah; Hyouk Soo Han; Kwan Kim; Du-Jeon Jang

    Photon-initiated shape transformation of n-alkanethiol-derivatized noble metal nanoparticles has been studied with variations of metal, alkanethiol, and solvent. Silver nanoparticles undergo fragmentation upon irradiation while gold ones barely do. Silver\\/gold composite particles follow the case of silver with a reduced efficiency. The efficiency decreases as alkanethiol length or solvent dipole moment increases. Following the conduction of thermalized photon energy, alkanethiol

  2. 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.

  3. The Noble plication: new indication for a historical procedure.

    PubMed

    Hochman, D J; Nivatvongs, S; Selvasekar, C R; Tantitemit, T

    2007-06-01

    Complications following ileal pouch-anal anastomosis (IPAA) have been well-described in the literature. While rare, small bowel volvulus following IPAA has been described. We describe the successful use of the modified Noble plication in such a patient with small bowel volvulus about an elongated mesentery. This largely 'historical' technique is well-suited to manage small bowel volvulus, especially when non-resectional management is preferred. PMID:17510738

  4. Ignition in alkane oxidation on noble-metal catalysts

    Microsoft Academic Search

    Götz Veser; Murtaza Ziauddin; Lanny D. Schmidt

    1999-01-01

    The ignition behavior in the oxidation of four simple alkanes (methane, ethane, propane and isobutane) with air on a platinum-foil catalyst, as well as that of ethane\\/air mixtures on four noble-metal foil catalysts (Pt, Pd, Rh, and Ir) was studied at atmospheric pressure over the entire range of fuel-to-air ratios. While, Pd showed the widest range of surface flammability, ignition

  5. Possible solar noble-gas component in Hawaiian basalts

    USGS Publications Warehouse

    Honda, M.; McDougall, I.; Patterson, D.B.; Doulgeris, A.; Clague, D.A.

    1991-01-01

    THE noble-gas elemental and isotopic composition in the Earth is significantly different from that of the present atmosphere, and provides an important clue to the origin and history of the Earth and its atmosphere. Possible candidates for the noble-gas composition of the primordial Earth include a solar-like component, a planetary-like component (as observed in primitive meteorites) and a component similar in composition to the present atmosphere. In an attempt to identify the contributions of such components, we have measured isotope ratios of helium and neon in fresh basaltic glasses dredged from Loihi seamount and the East Rift Zone of Kilauea1-3. We find a systematic enrichment in 20Ne and 21Ne relative to 22Ne, compared with atmospheric neon. The helium and neon isotope signatures observed in our samples can be explained by mixing of solar, present atmospheric, radiogenic and nucleogenic components. These data suggest that the noble-gas isotopic composition of the mantle source of the Hawaiian plume is different from that of the present atmosphere, and that it includes a significant solar-like component. We infer that this component was acquired during the formation of the Earth.

  6. Noble gas radionuclides in RBMK-1500-type reactor.

    PubMed

    Jasiulionis, Rimvydas; Adlys, Gediminas; Adliene, Diana; Vycinas, Linas

    2007-07-01

    The presence of noble gas and other short-lived radionuclides in air borne effluents from RBMK-1500-type reactor has been investigated using experimental and theoretical instrumentation for detection purposes. Activity concentrations of (85m)Kr, (87)Kr, (88)Kr, (135m)Xe, (135)Xe, (133)Xe and (41)Ar were measured in air emissions from Ignalina NPP using a special method and special equipment. Theoretical detection of reactor-borne radionuclides and investigation of their behaviour in a nuclear fuel during operation of nuclear reactor was performed using an analytical model based on reactor physics. An innovative method for the estimation of noble gas flow time from the defective nuclear fuel element through the ventilation stack of NPP to the atmosphere based on comparison of the experimentally and theoretically evaluated activity ratios of (88)Kr/(85m)Kr; (135)Xe/(133)Xe has been proposed. The estimated flow time of noble gas provides an excellent possibility to obtain modelling-based information about the qualitative and quantitative content of atmospheric releases from NPP. PMID:17383886

  7. EDITORIAL: Cold Quantum GasesEditorial: Cold Quantum Gases

    NASA Astrophysics Data System (ADS)

    Vassen, W.; Hemmerich, A.; Arimondo, E.

    2003-04-01

    This Special Issue of Journal of Optics B: Quantum and Semiclassical Optics brings together the contributions of various researchers working on theoretical and experimental aspects of cold quantum gases. Different aspects of atom optics, matter wave interferometry, laser manipulation of atoms and molecules, and production of very cold and degenerate gases are presented. The variety of subjects demonstrates the steadily expanding role associated with this research area. The topics discussed in this issue, extending from basic physics to applications of atom optics and of cold atomic samples, include: bulletBose--Einstein condensation bulletFermi degenerate gases bulletCharacterization and manipulation of quantum gases bulletCoherent and nonlinear cold matter wave optics bulletNew schemes for laser cooling bulletCoherent cold molecular gases bulletUltra-precise atomic clocks bulletApplications of cold quantum gases to metrology and spectroscopy bulletApplications of cold quantum gases to quantum computing bulletNanoprobes and nanolithography. This special issue is published in connection with the 7th International Workshop on Atom Optics and Interferometry, held in Lunteren, The Netherlands, from 28 September to 2 October 2002. This was the last in a series of Workshops organized with the support of the European Community that have greatly contributed to progress in this area. The scientific part of the Workshop was managed by A Hemmerich, W Hogervorst, W Vassen and J T M Walraven, with input from members of the International Programme Committee who are listed below. The practical aspects of the organization were ably handled by Petra de Gijsel from the Vrije Universiteit in Amsterdam. The Workshop was funded by the European Science Foundation (programme BEC2000+), the European Networks 'Cold Quantum Gases (CQG)', coordinated by E Arimondo, and 'Cold Atoms and Ultraprecise Atomic Clocks (CAUAC)', coordinated by J Henningsen, by the German Physical Society (DFG), by the Dutch Foundation for Fundamental Research on Matter (FOM) and by the Dutch Gelderland province. We thank all these sponsors and the members of the International Programme Committee for making the Workshop such a success. At this point we take the opportunity to express our gratitude to both authors and reviewers, for their efforts in preparing and ensuring the high quality of the papers in this special issue. Wim Vassen Vrije Universiteit, Amsterdam Andreas Hemmerich Universität Hamburg Ennio Arimondo Università di Pisa Guest Editors International Programme Committee A Aspect Orsay, France E Cornell Boulder, USA W Ertmer Hannover, Germany T W Haensch Munich, Germany A Hemmerich Hamburg, Germany W Hogervorst Amsterdam, The Netherlands D Kleppner Cambridge, USA C Salomon Paris, France G V Shlyapnikov Amsterdam, Paris, Moscow S Stringari Trento, Italy W Vassen Amsterdam, The Netherlands J T M Walraven Amsterdam, The Netherlands

  8. Inert anode containing base metal and noble metal useful for the electrolytic production of aluminum

    DOEpatents

    Ray, Siba P. (Murrysville, PA); Liu, Xinghua (Monroeville, PA)

    2000-01-01

    An inert anode for production of metals such as aluminum is disclosed. The inert anode comprises a base metal selected from Cu and Ag, and at least one noble metal selected from Ag, Pd, Pt, Au, Rh, Ru, Ir and Os. The inert anode may optionally be formed of sintered particles having interior portions containing more base metal than noble metal and exterior portions containing more noble metal than base metal. In a preferred embodiment, the base metal comprises Cu, and the noble metal comprises Ag, Pd or a combination thereof.

  9. Abating environmentally harmful waste gases

    NASA Astrophysics Data System (ADS)

    Sridhar, S.; Sichen, Du; Pal, U. B.; Seetharaman, S.

    2002-05-01

    A gas-purification method, based on the condensation of nitrogen, sulfur, and carbon-containing environmentally hazardous gases produced from industrial processes, is proposed in this article. The method, which utilizes the cooling capacity of waste nitrogen in the oxygen plant to condense the hazardous gases, is capable of removing hazardous impurities up to 99.98%. Theoretical calculations underlying the condensation process are presented employing gases produced in a blast furnace and coke oven in an integrated steel plant. The cooling power required for the condensation process is calculated using the waste nitrogen generated from an oxygen plant that generates captive oxygen for the steel plant. Design modifications that need to be made to the oxygen plant in order to utilize the cooling power of the waste nitrogen gas are also presented. As a case study, the advantages of the method are illustrated with purification of coke-oven gas. The economic impact and the investment aspects are also discussed.

  10. Heavy flavors

    SciTech Connect

    Cox, B.; Gilman, F.J.; Gottschalk, T.D.

    1986-11-01

    A range of issues pertaining to heavy flavors at the SSC is examined including heavy flavor production by gluon-gluon fusion and by shower evolution of gluon jets, flavor tagging, reconstruction of Higgs and W bosons, and the study of rare decays and CP violation in the B meson system. A specific detector for doing heavy flavor physics and tuned to this latter study at the SSC, the TASTER, is described. 36 refs., 10 figs.

  11. Attrition resistant catalysts and sorbents based on heavy metal poisoned FCC catalysts

    DOEpatents

    Gangwal, S.; Jothimurugesan, K.

    1999-07-27

    A heavy metal poisoned, spent FCC catalyst is treated by chemically impregnating the poisoned catalyst with a new catalytic metal or metal salt to provide an attrition resistant catalyst or sorbent for a different catalytic or absorption process, such as catalysts for Fischer-Tropsh Synthesis, and sorbents for removal of sulfur gases from fuel gases and flue-gases. The heavy metal contaminated FCC catalyst is directly used as a support for preparing catalysts having new catalytic properties and sorbents having new sorbent properties, without removing or passivating the heavy metals on the spent FCC catalyst as an intermediate step.

  12. Towards redistribution laser cooling of molecular gases: Production of candidate molecules SrH by laser ablation

    E-print Network

    Simon, Philipp; Weller, Lars; Sass, Anne; Weitz, Martin; 10.1117/12.2002379

    2013-01-01

    Laser cooling by collisional redistribution of radiation has been successfully applied in the past for cooling dense atomic gases. Here we report on progress of work aiming at the demonstration of redistribution laser cooling in a molecular gas. The candidate molecule strontium monohydride is produced by laser ablation of strontium dihydride in a pressurized noble gas atmosphere. The composition of the ablation plasma plume is analyzed by measuring its emission spectrum. The dynamics of SrH molecular density following the ablation laser pulse is studied as a function of the buffer gas pressure and the laser intensity.

  13. Isothermal compressors for process gases

    SciTech Connect

    Wiederuh, E.; Meinhart, D. (FH Giessen-Friedberg, Giessen (Germany))

    1992-09-01

    This paper reports on isothermal compressors which are more efficient for all gases. The study of several representative gases considered stage efficiencies, pressure ratios and pressure losses of the intercoolers. Generally there are two ways to reduce power consumption of a gas compression process: minimize losses of the compressor or improve the thermodynamics of the process. But there are some new ways to reduce losses of turbocompressors. Losses of the impeller labyrinth seals and the balance piston labyrinth seal can be reduced by optimizing the labyrinth geometry and minimizing labyrinth clearances. Therefore, conventional labyrinth seals are still being studied and will be improved.

  14. Method for detecting toxic gases

    DOEpatents

    Stetter, J.R.; Zaromb, S.; Findlay, M.W. Jr.

    1991-10-08

    A method is disclosed which is capable of detecting low concentrations of a pollutant or other component in air or other gas. This method utilizes a combination of a heating filament having a catalytic surface of a noble metal for exposure to the gas and producing a derivative chemical product from the component. An electrochemical sensor responds to the derivative chemical product for providing a signal indicative of the product. At concentrations in the order of about 1-100 ppm of tetrachloroethylene, neither the heating filament nor the electrochemical sensor is individually capable of sensing the pollutant. In the combination, the heating filament converts the benzyl chloride to one or more derivative chemical products which may be detected by the electrochemical sensor. 6 figures.

  15. Method for detecting toxic gases

    DOEpatents

    Stetter, Joseph R. (Naperville, IL); Zaromb, Solomon (Hinsdale, IL); Findlay, Jr., Melvin W. (Bolingbrook, IL)

    1991-01-01

    A method capable of detecting low concentrations of a pollutant or other component in air or other gas, utilizing a combination of a heating filament having a catalytic surface of a noble metal for exposure to the gas and producing a derivative chemical product from the component, and an electrochemical sensor responsive to the derivative chemical product for providing a signal indicative of the product. At concentrations in the order of about 1-100 ppm of tetrachloroethylene, neither the heating filament nor the electrochemical sensor is individually capable of sensing the pollutant. In the combination, the heating filament converts the benzyl chloride to one or more derivative chemical products which may be detected by the electrochemical sensor.

  16. Noble Gases in the Monahans Chondrite and Halite: Ar-39 - Ar-40 Age, Space Exposure Age, Trapped Solar Gases, and Neutron Fluence

    NASA Technical Reports Server (NTRS)

    Garrison, Daniel H.; Bogard, Donald D.

    2000-01-01

    For the Monahans chondrite and halite, we determined Ar-39 - Ar-40 ages of silicate = 4.53 Ga, halite > 4.3 Ga; a space exposure age of approx. 5 Ma; a regolith pre-irradiation; solar gas concentrations in the dark phase; and a regolith thermal neutron fluence.

  17. Greenhouse gases thinning the thermosphere

    NSDL National Science Digital Library

    Emmert et al.

    Orbital decay rates of satellites and other objects that have flown continually for more than 30 years were analyzed to determine the concentrations of greenhouse gases in the thermosphere. A decrease of 25 percent per decade was found in the thermosphere's density since 1966. Implications are discussed.

  18. Conduction of Electricity in Gases

    Microsoft Academic Search

    Alan Garscadden

    2006-01-01

    The conduction of electricity through gases has played ubiquitous roles in science and technology. It was responsible for many of the fundamental discoveries in atomic and molecular physics; gas discharge lighting is essential to every night operations; gas discharge lasers are still important in research and manufacturing; and all of advanced microelectronics depends on plasma enhanced processing. To a large

  19. Feshbach Resonances in Ultracold Gases

    NASA Astrophysics Data System (ADS)

    Kokkelmans, Servaas

    2015-09-01

    In this chapter, we describe scattering resonance phenomena in general, and focus on the mechanism of Feshbach resonances, for which a multi-channel treatment is required. We derive the dependence of the scattering phase shift on magnetic field and collision energy. From this, the scattering length and effective range coefficient can be extracted -- expressions which are particularly useful for ultracold gases.

  20. On Classical Gases. Jacques Arnaud

    E-print Network

    Boyer, Edmond

    On Classical Gases. Jacques Arnaud Mas Liron, F30440 Saint Martial, France Laurent Chusseau IES n 5506 au CNRS, 161 rue Ada, F34392 Montpellier, France April 19, 2013 Abstract The ideal gas laws that these laws are independent of the laws of motion aside from the law of energy conservation. A single

  1. Solvation theory to provide a molecular interpretation of the hydrophobic entropy loss of noble-gas hydration

    NASA Astrophysics Data System (ADS)

    Jem Irudayam, Sheeba; Henchman, Richard H.

    2010-07-01

    An equation for the chemical potential of a dilute aqueous solution of noble gases is derived in terms of energies, force and torque magnitudes, and solute and water coordination numbers, quantities which are all measured from an equilibrium molecular dynamics simulation. Also derived are equations for the Gibbs free energy, enthalpy and entropy of hydration for the Henry's law process, the Ostwald process, and a third proposed process going from an arbitrary concentration in the gas phase to the equivalent mole fraction in aqueous solution which has simpler expressions for the enthalpy and entropy changes. Good agreement with experimental hydration free energies is obtained in the TIP4P and SPC/E water models although the solute's force field appears to affect the enthalpies and entropies obtained. In contrast to other methods, the approach gives a complete breakdown of the entropy for every degree of freedom and makes possible a direct structural interpretation of the well-known entropy loss accompanying the hydrophobic hydration of small non-polar molecules under ambient conditions. The noble-gas solutes experience only a small reduction in their vibrational entropy, with larger solutes experiencing a greater loss. The vibrational and librational entropy components of water actually increase but only marginally, negating any idea of water confinement. The term that contributes the most to the hydrophobic entropy loss is found to be water's orientational term which quantifies the number of orientational minima per water molecule and how many ways the whole hydrogen-bond network can form. These findings help resolve contradictory deductions from experiments that water structure around non-polar solutes is similar to bulk water in some ways but different in others. That the entropy loss lies in water's rotational entropy contrasts with other claims that it largely lies in water's translational entropy, but this apparent discrepancy arises because of different coordinate definitions and reference frames used to define the entropy terms.

  2. Evaluating Gas-Phase Transport And Detection Of Noble Gas Signals From Underground Nuclear Explosions Using Chemical Tracers

    NASA Astrophysics Data System (ADS)

    Carrigan, C. R.; Hunter, S. L.; Sun, Y.; Wagoner, J. L.; Ruddle, D.; Anderson, G.; Felske, D.; Myers, K.; Zucca, J. J.; Emer, D. F.; Townsend, M.; Drellack, S.; Chipman, V.; Snelson, C. M.

    2013-12-01

    The 1993 Non-Proliferation Experiment (NPE) involved detonating 1 kiloton of chemical explosive in a subsurface cavity which also contained bottles of tracer gases (ref 1). That experiment provided an improved understanding of transport processes relevant to the detection of noble gas signals at the surface emanating from a clandestine underground nuclear explosion (UNE). As an alternative to performing large chemical detonations to simulate gas transport from UNEs, we have developed a test bed for subsurface gas transport, sampling and detection studies using a former UNE cavity. The test bed site allows for the opportunity to evaluate pathways to the surface created by the UNE as well as possible transport mechanisms including barometric pumping and cavity pressurization (ref 2). With the test bed we have monitored long-term chemical tracers as well as newly injected tracers. In order to perform high temporal resolution tracer gas monitoring, we have also developed a Subsurface Gas Smart Sampler (SGSS) which has application during an actual On Site Inspection (OSI) and is available for deployment in OSI field exercises planned for 2014. Deployment of five SGSS at the remote test bed has provided unparalleled detail concerning relationships involving tracer gas transport to the surface, barometric fluctuations and temporal variations in the natural radon concentration. We anticipate that the results of our tracer experiments will continue to support the development of improved noble gas detection technology for both OSI and International Monitoring System applications. 1. C.R. Carrigan et al., 1996, Nature, 382, p. 528. 2. Y. Sun and C.R. Carrigan, 2012, Pure Appl. Geophys., DOI 10.1007/s00024-012-0514-4.

  3. Ignition dynamics of dry-etched vertical cavity single-hole microdischarge reactors in ac regime operating in noble gases

    NASA Astrophysics Data System (ADS)

    Kulsreshath, M. K.; Golda, J.; Felix, V.; Schulz-von der Gathen, V.; Dussart, R.

    2014-08-01

    Silicon-based multi-cavity microdischarge reactors allow the generation of large-area uniform glow discharges over a wide pressure range up to atmospheric pressure. These devices, fabricated using micro electro-mechanical system technology, have shown complex interactions between the individual cavities. To discriminate these interactions, devices with only one shallow vertical cavity are studied here. Operation characteristics are investigated using electrical and optical analysing techniques. The spatial and temporal dynamics of the discharge are investigated for positive and negative voltage polarity of the applied ac voltage ramp by phase-resolved imaging. Within each voltage half-period, emission from the single cavity shows repetitive pulsing features and distinct spatial distributions. In the positive half-period, ring-shaped structures develop, while the negative half-period is distinguished by a bell-shaped intensity distribution. Effects of pressure and operation frequency on the spatial and temporal intensity profiles are discussed.

  4. Recombination-amplitude calculations of noble gases, in both length and acceleration forms, beyond the strong-field approximation

    E-print Network

    Bhardwaj, Siddharth

    Transition of an electron from a free to a bound state is critical in determining the qualitative shape of the spectrum in high-order-harmonic generation (HHG), and in tomographic imaging of orbitals. We calculate and ...

  5. Regional groundwater focusing of nitrogen and noble gases into the Hugoton-Panhandle giant gas field, USA

    Microsoft Academic Search

    Chris J. Ballentine; Barbara Sherwood Lollar

    2002-01-01

    The Hugoton-Panhandle giant gas field, located across SW Kansas and the Texas and Oklahoma panhandles in the USA, is the case type example of high nitrogen concentrations in a natural gas being linked with high helium concentrations. We collected 31 samples from producing wells in a north-south traverse of the 350-km-long field. The samples reflect the previously observed north-south change

  6. Compression behaviors of binary skutterudite CoP3 in noble gases up to 40 GPa at room temperature.

    PubMed

    Niwa, Ken; Nomichi, Daisuke; Hasegawa, Masashi; Okada, Taku; Yagi, Takehiko; Kikegawa, Takumi

    2011-04-18

    The binary skutterudite CoP(3) has a large void at the body-centered site of each cubic unit cell and is, therefore, called a nonfilled skutterudite. We investigated its room-temperature compression behavior up to 40.4 GPa in helium and argon using a diamond-anvil cell. High-pressure in situ X-ray diffraction and Raman scattering measurements found no phase transition and a stable cubic structure up to the maximum pressure in both media. A fitting of the present pressure-volume data to the third-order Birch-Murnaghan equation of state yields a zero-pressure bulk modulus K(0) of 147(3) GPa [pressure derivative K(0)' of 4.4(2)] and 171(5) GPa [where K(0)' = 4.2(4)] in helium and argon, respectively. The Gru?neisen parameter was determined to be 1.4 from the Raman scattering measurements. Thus, CoP(3) is stiffer than other binary skutterudites and could therefore be used as a host cage to accommodate large atoms under high pressure without structural collapse. PMID:21405026

  7. Adsorption and desorption of noble gases on activated charcoal: II. sup 222 Rn studies in a monolayer and packed bed

    SciTech Connect

    Scarpitta, S.C.; Harley, N.H. (Department of Energy, New York, NY (USA))

    1990-10-01

    The adsorptive and desorptive characteristics of canisters containing a petroleum-based charcoal were investigated under controlled conditions of temperature, relative humidity, and Rn concentration. Charcoals exposed in a monolayer and packed bed during exposure intervals of 1-7 d demonstrate that Rn adsorption and desorption are dependent on bed depth and the amount of water adsorbed. Changes in the adsorptive and desorptive properties of the charcoal occurred near the break-point where the pores became occluded by water vapor that condenses in the entrance capillaries. Radon-222 adsorption is decreased by an order of magnitude as the amount of adsorbed water exceeds the break-point of the charcoal. The reduction in pore surface due to adsorbed water results in a marked increase in the rate of Rn loss from exposed canisters, accounting for reduced adsorption. The apparent desorption time-constant for a 2-cm bed of loose Witco 6 x 10 mesh charcoal containing 0.220-0.365 kg H{sub 2}O kg-1 is typically between 2-8 h. The apparent desorption time-constant for an equivalent packed bed containing a water vapor content of 0.026-0.060 kg H{sub 2}O kg-1, which is below the break-point of the charcoal, is about 15-30 h. Conventional charcoal canisters, if exposed in the fully-opened configuration, can achieve the break-point in less than 4 d at 70% humidity. The use of a diffusion barrier would allow for longer exposure times until the break-point of the charcoal is achieved.

  8. Mechanical response of noble gas films to an oscillating substrate

    NASA Astrophysics Data System (ADS)

    Kobayashi, Hajime; Taniguchi, Junko; Suzuki, Masaru; Miura, Kouji; Arakawa, Ichiro

    2012-12-01

    We carried out quartz-crystal microbalance (QCM) experiments for Xe films adsorbed on an exfoliated single-crystalline graphite substrate (Xe/Gr) and Kr 1ms adsorbed on a synthetic mica substrate (Kr/mica) around LN2 temperature. For Xe/Gr, it was found that the resonance frequency decreases greatly around the first layer completion, while it does not decrease at low coverages. The observed behavior is similar to that of Kr films on a graphite substrate (Kr/Gr). This demonstrates that the layer completion strongly affects the sliding motion of noble gas films on graphite.

  9. Nanoparticles of noble metals in the supergene zone

    NASA Astrophysics Data System (ADS)

    Zhmodik, S. M.; Kalinin, Yu. A.; Roslyakov, N. A.; Mironov, A. G.; Mikhlin, Yu. L.; Belyanin, D. K.; Nemirovskaya, N. A.; Spiridonov, A. M.; Nesterenko, G. V.; Airiyants, E. V.; Moroz, T. N.; Bul'bak, T. A.

    2012-04-01

    Formation of noble metal nanoparticles is related to various geological processes in the supergene zone. Dispersed mineral phases appear during weathering of rocks with active participation of microorganisms, formation of soil, in aqueous medium and atmosphere. Invisible gold and other noble metals are incorporated into oxides, hydroxides, and sulfides, as well as in dispersed organic and inorganic carbonic matter. Sulfide minerals that occur in bedrocks and ores unaltered by exogenic processes and in cementation zone are among the main concentrators of noble metal nanoparticles. The ability of gold particles to disaggregate is well-known and creates problems in technological and analytical practice. When Au and PGE nanoparticles and clusters occur, these problems are augmented because of their unusual reactions and physicochemical properties. The studied gold, magnetite, titanomagnetite and pyrite microspherules from cementation zone and clay minerals of laterites in Republic of Guinea widen the knowledge of their abundance and inferred formation conditions, in particular, in the contemporary supergene zone. Morphology and composition of micrometer-sized Au mineral spherules were studied with SEM and laser microprobe. The newly formed segregations of secondary gold on the surface of its residual grains were also an object of investigation. The character of such overgrowths is the most indicative for nanoparticles. The newly formed Au particles provide evidence for redistribution of ultradispersed gold during weathering. There are serious prerequisites to state that microorganisms substantially control unusual nano-sized microspherical morphology of gold particles in the supergene zone. This is supported by experiments indicating active absorption of gold by microorganisms and direct evidence for participation of Ralstonia metallidurans bacteria in the formation of peculiar corroded bacteriomorphic surface of gold grains. In addition, the areas enriched in carbon and nitrogen have been detected with SEM on the surface of gold spherules from Guinea. Such organic compounds as serine, alanine, and glycine are identified on their surface with Raman spectroscopy. The experiments have been carried out and new data have been obtained indicating the role of micromycetes in concentration and distribution of noble metals in ferromanganese nodules of the World Ocean. Au and Pt were detected in the system with radioisotopes. It has been established that two forms of gold distribution develop within pseudomorphs of fungi colonies: (1) as pseudomorphic concentrates and (2) dispersed form unrelated to the colony structure. Inhomogeneities in distribution of dispersed platinum are manifested in the form of linear anomalies with elevated concentrations at the margins of the colonies.

  10. Measurements of relative photoemission time delays in noble gas atoms

    NASA Astrophysics Data System (ADS)

    Guénot, D.; Kroon, D.; Balogh, E.; Larsen, E. W.; Kotur, M.; Miranda, M.; Fordell, T.; Johnsson, P.; Mauritsson, J.; Gisselbrecht, M.; Varjù, K.; Arnold, C. L.; Carette, T.; Kheifets, A. S.; Lindroth, E.; L?Huillier, A.; Dahlström, J. M.

    2014-12-01

    We determine relative photoemission time delays between valence electrons in different noble gas atoms (Ar, Ne and He) in an energy range between 31 and 37 eV. The atoms are ionized by an attosecond pulse train synchronized with an infrared laser field and the delays are measured using an interferometric technique. We compare our results with calculations using the random phase approximation with exchange and multi-configurational Hartree–Fock. We also investigate the influence of the different ionization angular channels. .

  11. TUDE DE LA RSISTIVIT ET DU POUVOIR THERMOLECTRIQUE DES IMPURETS DISSOUTES DANS LES MTAUX NOBLES

    E-print Network

    Paris-Sud XI, Université de

    électriques des impuretés poly- valentes dissoutes dans les métaux nobles. Des effets de résonance liés à l nobles. LE JOURNAL DE PHYSIQUE ET LE RADIUM TOME 17, JANVIER 1956, 1. Introduction. 2013 Nous étudions

  12. Noninvasive noble metal nanoparticle arrays for surface-enhanced Raman spectroscopy of proteins

    Microsoft Academic Search

    Obianuju Inya-Agha; Robert J. Forster; Tia E. Keyes

    2007-01-01

    Noble metal nanoparticles arrays are well established substrates for surface enhanced Raman spectroscopy (SERS). Their ability to enhance optical fields is based on the interaction of their surface valence electrons with incident electromagnetic radiation. In the array configuration, noble metal nanoparticles have been used to produce SER spectral enhancements of up to 108 orders of magnitude, making them useful for

  13. RISK REDUCTION VIA GREENER SYNTHESIS OF NOBLE METAL NANOSTRUCTURES AND NANOCOMPOSITES

    EPA Science Inventory

    Aqueous preparation of nanoparticles using vitamins B2 and C which can function both as reducing and capping agents are described. Bulk and shape-controlled synthesis of noble nanostructures via microwave (MW)-assisted spontaneous reduction of noble metal salts using a-D-glucose,...

  14. ccsd-00002151,version1-25Jun2004 Modelisation of transition and noble metal vicinal

    E-print Network

    Boyer, Edmond

    ccsd-00002151,version1-25Jun2004 Modelisation of transition and noble metal vicinal surfaces, F-91 405 Orsay, France #12;Abstract. The energetics of transition and noble metal (Rh, Pd, Cu]. On the contrary, in the case of transition metals, T

  15. Chemistry of Carbon Gases in Volcanic Gases on Io

    Microsoft Academic Search

    L. Schaefer; B. Fegley Jr.

    2004-01-01

    We use chemical equilibrium calculations to model the chemistry of carbon in volcanic gases on Io (Schaefer and Fegley 2004, ApJ, in review). The calculations covered temperatures from 500 - 2000 K, pressures from 10-8 to 10+2 bars, and bulk O\\/S atomic ratios from ˜ 0 to 3. These conditions overlap the nominal conditions at Pele, where T = 1760

  16. Toxicity of pyrolysis gases from polypropylene

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Schneider, J. E.; Brauer, D. F.

    1979-01-01

    A sample of polypropylene was evaluated for toxicity of pyrolysis gases, using the toxicity screening test method developed at the University of San Francisco. The gases from this sample appeared to be equivalent or less toxic than the gases from a sample of polyethylene under these particular test conditions. Carbon monoxide appeared to be the principal toxicant.

  17. Flammability of methane, propane, and hydrogen gases

    Microsoft Academic Search

    Kenneth L. Cashdollar; Isaac A. Zlochower; Gregory M. Green; Richard A. Thomas; Martin Hertzberg

    2000-01-01

    This paper reports the results of flammability studies for methane, propane, hydrogen, and deuterium gases in air conducted by the Pittsburgh Research Laboratory. Knowledge of the explosion hazards of these gases is important to the coal mining industry and to other industries that produce or use flammable gases. The experimental research was conducted in 20 L and 120 L closed

  18. A critical review on the heterogeneous catalytic oxidation of elemental mercury in flue gases.

    PubMed

    Gao, Yanshan; Zhang, Zhang; Wu, Jingwen; Duan, Linhai; Umar, Ahmad; Sun, Luyi; Guo, Zhanhu; Wang, Qiang

    2013-10-01

    Nowadays, an increasing attention has been paid to the technologies for removing mercury from flue gases. Up to date, no optimal technology that can be broadly applied exists, but the heterogeneous catalytic oxidation of mercury is considered as a promising approach. Based on a brief introduction of the pros and cons of traditional existing technologies, a critical review on the recent advances in heterogeneous catalytic oxidation of elemental mercury is provided. In this contribution, four types of Hg oxidation catalysts including noble metals, selective catalytic reduction (SCR) catalysts, transition metals, and fly ash have been summarized. Both the advantages and disadvantages of these catalysts are described in detail. The influence of various acidic gases including SO2, SO3, NH3, NOx, HCl, Cl2, etc. have been discussed as well. We expect this work will shed light on the development of heterogeneous catalytic oxidation of elemental mercury technology in flue gases, particularly the synthesis of novel and highly efficient Hg(0) oxidation catalysts. PMID:23991895

  19. Isotopic Analysis and Evolved Gases

    NASA Technical Reports Server (NTRS)

    Swindle, Timothy D.; Boynton, William V.; Chutjian, Ara; Hoffman, John H.; Jordan, Jim L.; Kargel, Jeffrey S.; McEntire, Richard W.; Nyquist, Larry

    1996-01-01

    Precise measurements of the chemical, elemental, and isotopic composition of planetary surface material and gases, and observed variations in these compositions, can contribute significantly to our knowledge of the source(s), ages, and evolution of solar system materials. The analyses discussed in this paper are mostly made by mass spectrometers or some other type of mass analyzer, and address three broad areas of interest: (1) atmospheric composition - isotopic, elemental, and molecular, (2) gases evolved from solids, and (3) solids. Current isotopic data on nine elements, mostly from in situ analysis, but also from meteorites and telescopic observations are summarized. Potential instruments for isotopic analysis of lunar, Martian, Venusian, Mercury, and Pluto surfaces, along with asteroid, cometary and icy satellites, surfaces are discussed.

  20. Using noble gas tracers to estimate residual CO2 saturation in the field: results from the CO2CRC Otway residual saturation and dissolution test

    NASA Astrophysics Data System (ADS)

    LaForce, T.; Ennis-King, J.; Paterson, L.

    2013-12-01

    Residual CO2 saturation is a critically important parameter in CO2 storage as it can have a large impact on the available secure storage volume and post-injection CO2 migration. A suite of single-well tests to measure residual trapping was conducted at the Otway test site in Victoria, Australia during 2011. One or more of these tests could be conducted at a prospective CO2 storage site before large-scale injection. The test involved injection of 150 tonnes of pure carbon dioxide followed by 454 tonnes of CO2-saturated formation water to drive the carbon dioxide to residual saturation. This work presents a brief overview of the full test sequence, followed by the analysis and interpretation of the tests using noble gas tracers. Prior to CO2 injection krypton (Kr) and xenon (Xe) tracers were injected and back-produced to characterise the aquifer under single-phase conditions. After CO2 had been driven to residual the two tracers were injected and produced again. The noble gases act as non-partitioning aqueous-phase tracers in the undisturbed aquifer and as partitioning tracers in the presence of residual CO2. To estimate residual saturation from the tracer test data a one-dimensional radial model of the near-well region is used. In the model there are only two independent parameters: the apparent dispersivity of each tracer and the residual CO2 saturation. Independent analysis of the Kr and Xe tracer production curves gives the same estimate of residual saturation to within the accuracy of the method. Furthermore the residual from the noble gas tracer tests is consistent with other measurements in the sequence of tests.

  1. Designing materials for plasmonic systems: the alkali-noble intermetallics.

    PubMed

    Blaber, M G; Arnold, M D; Ford, M J

    2010-03-10

    We use electronic structure calculations based upon density functional theory to search for ideal plasmonic materials among the alkali-noble intermetallics. Importantly, we use density functional perturbation theory to calculate the electron-phonon interaction and from there use a first order solution to the Boltzmann equation to estimate the phenomenological damping frequency in the Drude dielectric function. We discuss the necessary electronic features of a plasmonic material and investigate the optical properties of the alkali-noble intermetallics in terms of some generic plasmonic system quality factors. We conclude that at low negative permittivities, KAu, with a damping frequency of 0.0224 eV and a high optical gap to bare plasma frequency ratio, outperforms gold and to some extent silver as a plasmonic material. Unfortunately, a low plasma frequency (1.54 eV) reduces its utility in modern plasmonics applications. We also discuss, briefly, the effect of local fields on the optical properties of these materials. PMID:21389416

  2. Annihilation in Gases and Galaxies

    NASA Technical Reports Server (NTRS)

    Drachman, Richard J. (editor)

    1990-01-01

    This publication contains most of the papers, both invited and contributed, that were presented at the Workshop of Annihilation in Gases and Galaxies. This was the fifth in a biennial series associated with the International Conference on the Physics of Electronic and Atomic Collisions. Subjects covered included the scattering and annihilation of positrons and positronium atoms in various media, including those of astrophysical interest. In addition, the topics of antimatter and dark matter were covered.

  3. Heavy Flavors

    NASA Astrophysics Data System (ADS)

    Cox, B.; Soni, A.

    This is a summary report of the working group on Heavy Flavors. Discussions at the workshop were centered on B physics and on the signals for heavy quarks and leptons at the SSC. The Working Group Members were: V. Barger, H.-U. Bengtsson, C. Buchanan, I. Bigi, M. Block, B. Cox, N. Glover, J. Hewett, W.Y. Keung, B. Margolis, T. Rizzo, M. Suzuki, A. Soni, D. Stork, and S. Willenbrock.

  4. Heavy Lifting

    NSDL National Science Digital Library

    Deborah A. Shearer

    2012-06-26

    In this activity, learners work in NASA teams to build balloon-powered rockets using identical parts and compete to launch the greatest number of paper clips to "space" (the ceiling). The rockets learners build model the Ares V heavy lift launchers that carry heavy payloads into orbit. This lesson plan includes background information, tips, discussion questions and answers, and a "Mission Report" sheet for learners.

  5. Synergistic effect of Brønsted acid and platinum on purification of automobile exhaust gases.

    PubMed

    Fu, Wei; Li, Xin-Hao; Bao, Hong-Liang; Wang, Kai-Xue; Wei, Xiao; Cai, Yi-Yu; Chen, Jie-Sheng

    2013-01-01

    The catalytic purification of automobile exhaust gases (CO, NOx and hydrocarbons) is one of the most practiced conversion processes used to lower the emissions and to reduce the air pollution. Nevertheless, the good performance of exhaust gas purification catalysts often requires the high consumption of noble metals such as platinum. Here we report that the Brønsted acid sites on the external surface of a microporous silicoaluminophosphate (SAPO) act as a promoter for exhaust gas purification, effectively cutting the loading amount of platinum in the catalyst without sacrifice of performance. It is revealed that in the Pt-loaded SAPO-CHA catalyst, there exists a remarkable synergistic effect between the Brønsted acid sites and the Pt nanoparticles, the former helping to adsorb and activate the hydrocarbon molecules for NO reduction during the catalytic process. The thermal stability of SAPO-CHA also makes the composite catalyst stable and reusable without activity decay. PMID:23907148

  6. Calculation of the effect of pressurizing gases on the resonant modes of single-crystal parallelepiped.

    PubMed

    Beck, D E

    2011-02-01

    Resonant ultrasound spectroscopy provides for an experimental determination of the elastic moduli of a solid sample. The moduli are extracted by matching a theoretically computed resonant spectrum to the experimental vibrational spectrum. To determine the pressure dependence of the moduli, the vibrational spectrum can be taken with the sample in a pressurizing gas. Then the extraction of the intrinsic, pressure dependent moduli requires a theoretical treatment which permits removal of the perturbation of the spectrum due to the surface loading by the pressure and shear waves in the gas. In order to illustrate a treatment which accomplishes this removal, the theoretically computed frequency shifts and the quality factors are reported for two single-crystal parallelepiped pressurized by noble gases. PMID:20822786

  7. Synergistic effect of Brønsted acid and platinum on purification of automobile exhaust gases

    PubMed Central

    Fu, Wei; Li, Xin-Hao; Bao, Hong-Liang; Wang, Kai-Xue; Wei, Xiao; Cai, Yi-Yu; Chen, Jie-Sheng

    2013-01-01

    The catalytic purification of automobile exhaust gases (CO, NOx and hydrocarbons) is one of the most practiced conversion processes used to lower the emissions and to reduce the air pollution. Nevertheless, the good performance of exhaust gas purification catalysts often requires the high consumption of noble metals such as platinum. Here we report that the Brønsted acid sites on the external surface of a microporous silicoaluminophosphate (SAPO) act as a promoter for exhaust gas purification, effectively cutting the loading amount of platinum in the catalyst without sacrifice of performance. It is revealed that in the Pt-loaded SAPO-CHA catalyst, there exists a remarkable synergistic effect between the Brønsted acid sites and the Pt nanoparticles, the former helping to adsorb and activate the hydrocarbon molecules for NO reduction during the catalytic process. The thermal stability of SAPO-CHA also makes the composite catalyst stable and reusable without activity decay. PMID:23907148

  8. Electrodeposition of ultrathin Pd, Co and Bi films on well-defined noble-metal electrodes: studies by ultrahigh vacuum-electrochemistry (UHV-EC)

    E-print Network

    Baricuatro, Jack Hess L

    2006-10-30

    Three illustrative cases involving the electrodeposition of ultrathin metal films of varying reactivities onto noble-metal substrates were investigated: (i) Pd on Pt(111), a noble admetal on a noble-metal surface; (ii) Bi on Pd(111), a less noble...

  9. Electrochemical analysis of clinical blood-gases, gases and vapours.

    PubMed

    Hahn, C E

    1998-06-01

    This tutorial review charts the development of electrochemical sensors for the analysis of blood-gases, gases and vapours in clinical medicine over the past four decades. The development of each sensor is set in its historical and clinical context, and the first part of the review concentrates on aqueous electrolyte electrochemistry and on those sensors which have made a major impact on the clinical measurement of the partial pressures of oxygen and carbon dioxide in the blood. The electrochemical interference effects of anaesthetic agents on these measurements are also described. Those electrochemical sensors which have failed, in the past, to make a clear impact in this area are not considered, but the few attempts to devise aqueous electrolyte electrochemical sensors for anaesthetic agent measurement are reviewed. The second part of the review describes the chequered history of the development of non-aqueous solvent electrochemical sensors to measure the partial pressures of oxygen and carbon dioxide, in both the presence and absence of each other, in the gas phase. The last part of the review examines various attempts, using non-aqueous solvent electrochemistry, to measure the concentration of inhalational anaesthetic vapours in the gas phase. These sensors have yet to make an impact on clinical practice. Throughout this tutorial review, theoretical models of membrane-covered electrochemical sensors are described where appropriate. This review represents a personal view of the development of electrochemical sensors for clinical measurement, and it is therefore necessarily selective in its approach and emphasis. PMID:9764506

  10. C5Li7(+) and O2Li5(+) as noble-gas-trapping agents.

    PubMed

    Pan, Sudip; Contreras, Maryel; Romero, Jonathan; Reyes, Andres; Chattaraj, Pratim K; Merino, Gabriel

    2013-02-11

    The noble-gas-trapping ability of the star-shaped C(5)Li(7)(+) cluster and O(2)Li(5)(+) super-alkali cluster is studied by using ab initio and density functional theory (DFT) at the MP2 and M05-2X levels with 6-311+G(d,p) and 6-311+G(d) basis sets. These clusters are shown to be effective noble-gas-trapping agents. The stability of noble-gas-loaded clusters is analyzed in terms of dissociation energies, reaction enthalpies, and conceptual DFT-based reactivity descriptors. The presence of an external electric field improves the dissociation energy. PMID:23296901

  11. Atmospheric Chemistry and Greenhouse Gases

    Microsoft Academic Search

    D. Schimel; D. Glover; J. Melack; R. Beer; R. Myneni

    Contents4.1 Earth Observing System (EOS) program objectives 1674.2 Introduction 1684.2.1 Science questions 1684.2.1.1 How does changing land\\/land use affect fluxes of greenhouse gases such asCO 2 , methane, and nitrous oxide? How does it affect O 3 precursors fromsoil (e.g., NO), plant (e.g., biogenic nonmethane hydrocarbons), emissions,and biomass-burning plumes? 1684.2.1.2 How does interannual variability in climate affect interannual variability inbiogeochemistry?

  12. Climate Change and Greenhouse Gases

    NASA Technical Reports Server (NTRS)

    Ledley, Tamara S.; Sundquist, Eric; Schwartz, Stephen; Hall, Dorothy K.; Fellows, Jack; Killeen, Timothy

    1999-01-01

    The American Geophysical Union (AGU), as a scientific organization devoted to research on the Earth and space sciences, provides current scientific information to the public on issues pertinent to geophysics. The Council of the AGU approved a position statement on Climate Change and Greenhouse Gases in December 1998. The statement, together with a short summary of the procedures that were followed in its preparation, review, and adoption were published in the February 2, 1999 issue of Eos ([AGU, 1999]. The present article reviews scientific understanding of this issue as presented in peer-reviewed publications that serves as the underlying basis of the position statement.

  13. Spectra of Stable Non-Noble Gas Single Bubble Sonoluminescence

    E-print Network

    Levinsen, M T; Levinsen, Mogens T.; Dam, Jeppe Seidelin

    2006-01-01

    A commonly accepted view is that stable Single Bubble Sonoluminescence (SBSL) can only be achieved in the presence of a noble gas or hydrogen. In air-seeded bubbles, the content of diatomic gasses is burned off to leave the small amount of argon needed to sustain stable operation. Here we report that long term stable SBSL can be sustained with only nitrogen, oxygen, or nitrogen/oxygen mixtures being present. Compared to that of a stable argon bubble, the emission is much weaker and the spectrum looks much colder. Oscillating states as well as recycling states are also observed. An intriguing saturation effect seems connected with the presence of water vapor in the bubble.

  14. Predicted organic noble-gas hydrides derived from acrylic Acid.

    PubMed

    Zhang, Min; Gao, Kunqi; Sheng, Li

    2015-03-19

    The Ar-, Kr-, and Xe-insertion compounds into acrylic acid, i.e., C2H3COONgH (Ng = Ar, Kr, and Xe), have been studied by ab initio calculations. The geometry optimization, frequency calculation, and stability were investigated at the MP2/aug-cc-pVTZ (aug-cc-pVTZ-PP) level of theory. Two configuration isomers, i.e., s-cis syn (isomer A) and s-cis anti (isomer B), were optimized for each molecule. Using the s-cis syn structure (isomer A) as an example, we performed natural bond orbital (NBO) analysis, natural energy decomposition analysis (NEDA), and atom-in-molecules (AIM) analysis to investigate the bonding nature of these noble-gas compounds. Our study predicts the existence of Kr- and Xe-derivatives of acrylic acid and the instability of Ar-related compounds. PMID:25340827

  15. Phonon dispersion of noble metal: Copper as a prototype

    NASA Astrophysics Data System (ADS)

    Pathan, T. K.; Patel, A. B.; Bhatt, N. K.; Thakore, B. Y.; Jani, A. R.

    2013-06-01

    The phonon dispersion curve (PDC) of liquid copper are reported based on the approach given by Hubbard and Beeby (HB), and compared with the available theoretical data. For the interaction between ions, the effective pair potential based on the pseudopotential theory is adopted. To describe the electron-ion interaction our newly proposed model potential is employed along with a Hartree screening function. The major focus of the study is to examine the influence of the valency in determining the dynamical properties of noble metals taking copper as a test case. The only potential-parameter, the core radius Rc, was determined by requiring reported q0 value of the form factor at T = 0K. Structure factor and pair correlation function g(r) have been determined within the Percus-Yevick (PY) approximation. Inferences drawn from the present study are also discussed.

  16. Optical spectra of noble metal nanoparticles supported on zeolites

    NASA Astrophysics Data System (ADS)

    López Bastidas, Catalina; Smolentseva, Elena; Machorro, Roberto; Petranovskii, Vitalii

    2014-09-01

    Optical spectra of noble metal nano-particles supported on different types of zeolites are studied and compared. The absorbance spectra of Cu, Ag and Au nanoparticles supported on mordenite, ?-zeolite, Na/Y and H/Y zeolites respectively are reported. Spectra for pre-exchanged Au-Cu/Na/Y, Au-Ni/Na/Y and Au-Fe/Na/Y are also studied. A simple effective medium approach (Maxwell-Garnett) is used to obtain a theoretical complex effective dielectric function of the composite and to asses the sensibility of the plasmon resonance to the sample characteristics. The knowledge of these properties can hopefully be applied to the development of optical tools to monitor the synthetic path.

  17. DEVELOPMENT OF A NON-NOBLE METAL HYDROGEN PURIFICATION SYSTEM

    SciTech Connect

    Korinko, P; Kyle Brinkman, K; Thad Adams, T; George Rawls, G

    2008-11-25

    Development of advanced hydrogen separation membranes in support of hydrogen production processes such as coal gasification and as front end gas purifiers for fuel cell based system is paramount to the successful implementation of a national hydrogen economy. Current generation metallic hydrogen separation membranes are based on Pd-alloys. Although the technology has proven successful, at issue is the high cost of palladium. Evaluation of non-noble metal based dense metallic separation membranes is currently receiving national and international attention. The focus of the reported work was to develop a scaled reactor with a VNi-Ti alloy membrane to replace a production Pd-alloy tube-type purification/diffuser system.

  18. Noble metal ionic sites for catalytic hydrogen combustion: spectroscopic insights.

    PubMed

    Deshpande, Parag A; Madras, Giridhar

    2011-01-14

    A catalytic hydrogen combustion reaction was carried out over noble metal catalysts substituted in ZrO(2) and TiO(2) in ionic form. The catalysts were synthesized by the solution combustion technique. The compounds showed high activity and CO tolerance for the reaction. The activity of Pd and Pt ion substituted TiO(2) was comparable and was higher than Pd and Pt ion substituted ZrO(2). The mechanisms of the reaction over the two supports were proposed by making use of the X-ray photoelectron spectroscopy and FT infrared spectroscopic observations. The reaction over ZrO(2) supported catalysts was proposed to take place by the utilization of the surface hydroxyl groups while the reaction over TiO(2) supported catalysts was hypothesized to be a hybrid mechanism utilizing surface hydroxyl groups and the lattice oxygen. PMID:21060910

  19. Predicting Flows of Rarefied Gases

    NASA Technical Reports Server (NTRS)

    LeBeau, Gerald J.; Wilmoth, Richard G.

    2005-01-01

    DSMC Analysis Code (DAC) is a flexible, highly automated, easy-to-use computer program for predicting flows of rarefied gases -- especially flows of upper-atmospheric, propulsion, and vented gases impinging on spacecraft surfaces. DAC implements the direct simulation Monte Carlo (DSMC) method, which is widely recognized as standard for simulating flows at densities so low that the continuum-based equations of computational fluid dynamics are invalid. DAC enables users to model complex surface shapes and boundary conditions quickly and easily. The discretization of a flow field into computational grids is automated, thereby relieving the user of a traditionally time-consuming task while ensuring (1) appropriate refinement of grids throughout the computational domain, (2) determination of optimal settings for temporal discretization and other simulation parameters, and (3) satisfaction of the fundamental constraints of the method. In so doing, DAC ensures an accurate and efficient simulation. In addition, DAC can utilize parallel processing to reduce computation time. The domain decomposition needed for parallel processing is completely automated, and the software employs a dynamic load-balancing mechanism to ensure optimal parallel efficiency throughout the simulation.

  20. THERMODYNAMIC PARAMETERS FOR DISSOLVED GASES*

    PubMed Central

    Hildebrand, Joel H.

    1969-01-01

    In 1958 and subsequently we correlated properties of solutions of gases in liquids by using the “force constants,” ?/k, and collision diameters, ?, which serve as parameters in equations for molecular pair potential energy such as that of Lennard-Jones or its variants. Unfortunately, however, the figures for these parameters that have been published are so scattered for the same gas as to make it difficult to select “best” values; in 1967, therefore, I substituted for these indirectly determined molecular parameters the directly and accurately known molal energy of vaporization, ?Ebv, and the molal volume, vb, of the liquefied gas, both at its boiling point. A plot of values of ?E2v against the most trustworthy values of ?/k reveals direct proportionality. The same is true for Vb1/3 versus ?. Recent examples will be shown of excellent linear correlations with these parameters of thermodynamic properties of different gases in the same solvent. It is no less “scientific” and far more practical to regard molecules of a solute as immersed in the potential energy field of its solvent than it is to split this field into imperfectly known pair potentials of questionable additivity and to try to integrate them over an undetermined distribution function. PMID:16591809

  1. Thermal efficiency of the principal greenhouse gases

    NASA Astrophysics Data System (ADS)

    Y. Galashev, A.; R. Rakhmanova, O.

    2015-01-01

    Atmospheric gases are ranked according to the efficiency with which they absorb and radiate longwave radiation. The open international HITRAN database of gaseous absorption lines of high resolution together with inverse Fourier transform were used. The autocorrelation functions of the total dipole moment of the basic greenhouse gases molecules such as H2O, CO2, O3, N2O, and CH4 were obtained. Absorption coefficient spectra and emission power spectra of infrared radiation of these gases were calculated. Analysis of the emissive ability of all gases under consideration was carried out. Compared to CO2, all the gases under investigation have more effective emission except ozone. An efficiency criterion of IR absorption and emission is defined and is calculated for each studied gas, and the gases are ranked accordingly as follows (from strong to weak): H2O, CH4, CO2, N2O, and O3.

  2. Electrowinningof Non-Noble Metalswith Simultaneous Hydrogen Evolutionat Flow-ThroughPorous Electrodes

    E-print Network

    Weidner, John W.

    - tion to the electrowinning of non-noble metals (e.g., Zn or Cr) faces complications caused, in this treatment, no gas evolution was considered. More recently Ateya et al. iv experimentally evaluated

  3. From (b)edouin to (a)borigine: the myth of the desert noble savage.

    PubMed

    Graulund, Rune

    2009-01-01

    This article examines the myth of the supposed superiority of the desert noble savage over civilized man. With the Bedouin of Arabia and the Aborigines of Australia as its two prime examples, the article argues that two versions of this myth can be traced: one in which the desert noble savage is valorized due to his valour, physical prowess and martial skill (Bedouin); and another, later version, where the desert noble savage is valorized as a pacifist, an ecologist and a mythmaker/storyteller (Aborigines). The article concludes by examining the way in which this turn from one type of desert noble savage to another reflects the manner in which western modernity has shifted its values from Cartesian dualities and Enlightenment rationalism to that of networks, potentialities, ecology and myth. PMID:19886291

  4. Seed-mediated growth of noble metal nanocrystals: crystal growth and shape control

    NASA Astrophysics Data System (ADS)

    Niu, Wenxin; Zhang, Ling; Xu, Guobao

    2013-03-01

    Controlled synthesis of noble metal nanocrystals has received enormous attention due to the ability of tailoring the properties of nanocrystals by tuning their shape, size, and composition. The seed-mediated growth method is one of the most reliable and versatile methods to control the shapes of noble metal nanocrystals. This feature article highlights recent strategies regarding shape-controlled synthesis of noble metal nanocrystals by the seed-mediated growth method, with the aim of introducing new strategies and offering new mechanistic insights into nanocrystal shape evolution. Critical parameters affecting the nucleation and growth of noble metal NCs are systemically introduced and analyzed. New developments of extended seed-mediated growth methods were also introduced. Finally, the perspectives of future research on the seed-mediated growth method are also discussed.

  5. 75 FR 12737 - Applications To Export Electric Energy; Noble Energy Marketing and Trade Corp.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-17

    ...as a power marketer using international transmission facilities located...utilities, Federal power marketing agencies, and other entities...connection of each of the international transmission facilities to...Joseph Limone, Noble Energy Marketing and Trade Corp., 333...

  6. CO oxidation studies over supported noble metal catalysts and single crystals: A review

    NASA Technical Reports Server (NTRS)

    Boecker, Dirk; Gonzalez, Richard D.

    1987-01-01

    The catalytic oxidation of CO over noble metal catalysts is reviewed. Results obtained on supported noble metal catalysts and single crystals both at high pressures and under UHV conditions are compared. The underlying causes which result in surface instabilities and multiple steady-state oscillations are considered, in particular, the occurrence of hot spots. CO islands of reactivity, surface oxide formation and phase transformations under oscillatory conditions are discussed.

  7. Effects of Noble Metal Promoters on In Situ Reduced Low Loading Ni Catalysts for Methane Activation

    Microsoft Academic Search

    Bjørn Christian Enger; Rune Lødeng; Anders Holmen

    2010-01-01

    The commercial potential for a given catalytic process may be influenced by requirements on metal loading, in particular where\\u000a noble metals are used. In an effort to substantially decrease the amount of catalyst material used for methane activation\\u000a and catalytic partial oxidation (CPO), the effect of 0.005 wt% noble metal (Rh, Ru, Pd or Pt) on 0.5 wt% Ni\\/?-Al2O 3

  8. Contemplation, the Noble, and the Mean: The Standard of Moral Virtue in Aristotle's Ethics

    E-print Network

    Tuozzo, Thomas

    1995-12-01

    Contemplation, the Noble, and the Mean: The Standard of Moral Virtue in Aristotle's Ethics Thomas M. Tuozzo Aristotle appears to make the following claims about the end of morally virtuous action: (1) Virtuous action is chosen for its own sake.... (2) Virtuous action is chosen for the sake of suSocijiovia. (3) Virtuous action is chosen for the sake of the noble. (4) Virtuous action is chosen for the sake of contemplation.1 Understanding Aristotle's ethical theory requires understanding how...

  9. Investigating the static dipole polarizability of noble-gas atoms confined in impenetrable spheres and shells

    NASA Astrophysics Data System (ADS)

    Ludlow, J. A.; Lee, Teck-Ghee

    2015-03-01

    The static dipole polarizability of noble-gas atoms confined by impenetrable spheres and spherical shells is studied using the B -spline random phase approximation with exchange. The general trend in dipole polarizabilities across the noble-gas sequence shows a decrease in the dipole polarizability as the volume of the confining impenetrable sphere is reduced and a large increase in the dipole polarizability for confinement by impenetrable spherical shells as the inner-shell radius is increased.

  10. Investigating the static dipole polarisability of noble gas atoms confined in impenetrable spheres and shells

    E-print Network

    Ludlow, J A

    2015-01-01

    The static dipole polarisability of noble gas atoms confined by impenetrable spheres and spherical shells is studied using the B-spline random phase with exchange approximation. The general trend in dipole polarisabilities across the noble gas sequence shows a decrease in the dipole polarisability as the volume of the confining impenetrable sphere is reduced and a large increase in the dipole polarisability for confinement by impenetrable spherical shells as the inner shell radius is increased.

  11. Recent advances in analytical and bioanalysis applications of noble metal nanorods

    Microsoft Academic Search

    Ilaria Mannelli; M.-Pilar Marco

    2010-01-01

    In the last decade the use of anisotropic nanoparticles in analytical and bioanalytical applications has increased substantially.\\u000a In particular, noble metal nanorods have unique optical properties that have attracted the interest of many research groups.\\u000a The localized surface plasmon resonance (LSPR) generated by interaction of light at a specific wavelength with noble metal\\u000a nanoparticles was found to depend on particle

  12. A nuclide-separation wire precipitator for measurement of noble-gas fission products

    Microsoft Academic Search

    M. Katagiri; M. Kishimoto; H. Ito; H. Yoshida; M. Fukushima; H. Ohkawa; T. Saruta

    1993-01-01

    A wire precipitator, which has a capability of determining separately the activity concentrations of three radioactive noble-gas fission products, 88Kr, 89Kr and 138Xe, was developed. The precipitator utilizes the characteristics that the respective daughter nuclides of the fission products emit beta particles of different energy spectra. The activity concentrations of the noble gas fission products were separately quantified even when

  13. Greenhouse Gases: The Overlooked Sources

    NSDL National Science Digital Library

    This radio broadcast, which took place during the Kyoto Conference on global warming, discusses well-known and more obscure sources of greenhouse gases. Solutions to reduce carbon emissions are discussed, including creating fuel with less carbon in it (biomass fuels); reducing driving by increasing the cost of fuel; and improving vehicle fuel economy. The broadcast then introduces the topic of methane as a greenhouse gas; although less is emitted, it is about fifty times more effective than carbon dioxide at warming the planet. Cattle are a major source of methane; some ideas are introduced for monitoring and reducing their emissions. There is also discussion of whether global warming could be a result of natural variability as opposed to the result of a human-caused greenhouse effect. The broadcast is 49 minutes and 39 seconds in length.

  14. Continuous Processing With Mars Gases

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde; Jennings, Paul

    2000-01-01

    Current Martian missions call for the production of oxygen for breathing, and fuel and oxygen for propulsion to be produced from atmospheric carbon dioxide (CO2). Adsorption and freezing are the two methods considered for capturing CO2 from the atmosphere. However, the nitrogen (N2) and argon (Ar), which make up less than 5 percent of the atmosphere, cause difficulties with both of these processes by blocking the CO2. This results in the capture process rapidly changing from a pressure driven process to a diffusion controlled process. To increase the CO2 capture rates, some type of mechanical pump is usually proposed to remove the N2 and Ar. The N2 and Ar are useful and have been proposed for blanketing and pressurizing fuel tanks and as buffer gas for breathing air for manned missions. Separation of the Martian gases with the required purity can be accomplished with a combination of membranes. These membrane systems do not require a high feed pressure and provide suitable separation. Therefore, by use of the appropriate membrane combination with the Martian atmosphere supplied by a compressor a continuous Supply Of CO2 for fuel and oxygen production can be supplied. This phase of our program has focused on the selection of the membrane system. Since permeation data for membranes did not exist for Martian atmospheric pressures and temperatures, this information had to be compiled. The general trend as the temperature was lowered was for the membranes to become more selective. In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar. This paper will present the membrane data, provide the design requirements for a compressor, and compare the results with adsorption and freezer methods.

  15. Continuous Processing with Mars Gases

    NASA Astrophysics Data System (ADS)

    Parrish, Clyde; Jennings, Paul

    2001-01-01

    Current Martian missions call for the production of oxygen for breathing, and fuel and oxygen for propulsion to be produced from atmospheric carbon dioxide (CO2). Adsorption and freezing are the two methods considered for capturing CO, from the atmosphere. However, the nitrogen (N2) and argon (Ar), which make up less than 5 percent of the atmosphere, cause difficulties with both of these processes by blocking the CO2, This results in the capture process rapidly changing from a pressure driven process to a diffusion controlled process. To increase the CO, capture rates, some type of mechanical pump is usually proposed to remove the N2 and Ar. The N2 and Ar are useful and have been proposed for blanketing and pressurizing fuel tanks and as buffer gas for breathing air for manned missions. Separation of the Martian gases with the required purity can be accomplished with a combination of membranes. These membrane systems do not require a high feed pressure and provide suitable separation. Therefore, by use of the appropriate membrane combination with the Martian atmosphere supplied by a compressor a continuous supply of CO2 for fuel and oxygen production can be supplied. This phase of our program has focused on the selection of the membrane system. Since permeation data for membranes did not exist for Martian atmospheric pressures and temperatures, this information had to be compiled. The general trend as the temperature was lowered was for the membranes to become more selective. In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar. This paper will present the membrane data, provide the design requirements for a compressor, and compare the results with adsorption and freezer methods.

  16. Attrition resistant catalysts and sorbents based on heavy metal poisoned FCC catalysts

    DOEpatents

    Gangwal, Santosh (Cary, NC); Jothimurugesan, Kandaswamy (Hampton, VA)

    1999-01-01

    A heavy metal poisoned, spent FCC catalyst is treated by chemically impregnating the poisoned catalyst with a new catalytic metal or metal salt to provide an attrition resistant catalyst or sorbent for a different catalytic or absorption processes, such as catalysts for Fischer-Tropsh Synthesis, and sorbents for removal of sulfur gasses from fuel gases and flue-gases. The heavy metal contaminated FCC catalyst is directly used as a support for preparing catalysts having new catalytic properties and sorbents having new sorbent properties, without removing or "passivating" the heavy metals on the spent FCC catalyst as an intermediate step.

  17. Interaction of intense laser pulses with noble gas clusters and droplets

    NASA Astrophysics Data System (ADS)

    Parra, Enrique

    The time resolved dynamics of high intensity (1014 - 1017 W/cm2) laser interactions with noble gas (argon and krypton) nanometer-sized clusters and micron-sized droplets were experimentally investigated. For these investigations, a cryogenically cooled high-pressure pulsed gas jet, capable of stable operation in both cluster and droplet regimes, was specially constructed. The valve operation in the droplet mode, a regime not extensively studied in the literature, was characterized. Measurements of the total mass flow, the droplet size distributions, and droplet flow speeds as well as the temporal behavior of the valve were made and the results explained within the context of the phase diagrams for these gases and the dynamic operation of the valve. Measurements were presented of x-ray and extreme ultraviolet (EUV) emission from both clusters and droplets irradiated with constant energy, variable width laser pulses ranging from hundred femtoseconds to several nanoseconds. Resonant coupling was observed for both targets which was understood in terms of two time scales natural to the plasma: a short time scale for optimal resonant absorption at the critical density layer in the expanding plasma, and a longer time scale for the plasma to drop below critical density. Detailed simulations of the intense laser interaction with clusters, using a hydrodynamic model developed by our group, reveal a nonuniform expansion of the heated material which results in a long-time resonance of the laser field at the critical density plasma layer. Calculations simulating the variable pulse width measurements show resonant timescales in agreement with the experimental data. The temporal character of the laser-droplet interaction was further investigated using a series of pump-probe experiments monitoring the delay-dependent x-ray and EUV emission, and by imaging frequency-doubled probe light scattered from the interaction region. Depending on the spectral region of interest, the type of emission, and the droplet characteristics, the effective plasma lifetime was found to extend from a few hundred picoseconds to as long as several nanoseconds in agreement with expected plasma expansion, EUV excitation and recombination emission time scales.

  18. The intrusion of new magma triggered the 2011-2012 unrest at Santorini: evidence from noble-gas isotopes

    NASA Astrophysics Data System (ADS)

    Rizzo, A.; Barberi, F.; Carapezza, M.; Di Piazza, A.; Francalanci, L.; Sortino, F.; D'Alessandro, W.

    2013-12-01

    Santorini is one of the most famous active volcanoes of the world for its catastrophic explosive eruption that occurred during the Minoan civilization. Since then the Kameni eruptive centers that formed within the caldera erupted repeatedly until 1950. In 2011-2012 the volcano has been characterized by a seismic unrest, that was unprecedented at Santorini at least since the 1950 eruption, and that led to fear for an imminent eruption. Because more than 100,000 visitors are present on the island during the tourist season, and considering the eruptive potential of Santorini, it is crucial to evaluate the hazard of this volcano, which depends on the type of magma actually present in the volcanic system. With the aim to address this question, this research shows the first comparison between noble-gas isotope composition of the present fumarolic gases with that of fluid inclusions hosted in enclaves contained in the 1570 and 1925 AD dacitic magmas erupted at Nea Kameni. These enclaves are a portion of mafic magma batches that replenished the shallow chamber of the plumbing system hosting cooler and more silicic melts. Their Sr-Nd isotope ratios are quite similar to those measured in the host dacitic rocks, implying a common parental magma. Therefore, the analyzed enclaves may be considered representative of the historic magma erupted at Nea Kameni which could be still present in the volcano plumbing system feeding the crater fumaroles. The 3He/4He ratios of enclaves, once corrected for air contamination (3.1-3.6 Ra), partially overlap those of the gases (3.5-4.0 Ra) collected from Nea and Palea Kameni. The range of 3He/4He ratios (3.1-4.0 Ra) is appreciably lower than typical arc volcanoes (R/Ra ~7-8), implying that a contamination by 4He-rich fluids occurred either directly in the mantle and/or in the plumbing system. Comparison of 3He/4He and 4He/40Ar* ratios measured in enclaves with those of gases, as well as long-term monitoring of R/Ra in the latters, coherently indicate that the unrest in 2011-2012 was due to the injection into the plumbing system of a new batch of magma that is probably more mafic and less degassed than the basaltic-andesitic to dacitic magmas historically residing therein. All of the anomalies ceased in February 2012, suggesting that a new period of quiescence had been reestablished.

  19. Noble metal aerogels-synthesis, characterization, and application as electrocatalysts.

    PubMed

    Liu, Wei; Herrmann, Anne-Kristin; Bigall, Nadja C; Rodriguez, Paramaconi; Wen, Dan; Oezaslan, Mehtap; Schmidt, Thomas J; Gaponik, Nikolai; Eychmüller, Alexander

    2015-02-17

    CONSPECTUS: Metallic and catalytically active materials with high surface area and large porosity are a long-desired goal in both industry and academia. In this Account, we summarize the strategies for making a variety of self-supported noble metal aerogels consisting of extended metal backbone nanonetworks. We discuss their outstanding physical and chemical properties, including their three-dimensional network structure, the simple control over their composition, their large specific surface area, and their hierarchical porosity. Additionally, we show some initial results on their excellent performance as electrocatalysts combining both high catalytic activity and high durability for fuel cell reactions such as ethanol oxidation and the oxygen reduction reaction (ORR). Finally, we give some hints on the future challenges in the research area of metal aerogels. We believe that metal aerogels are a new, promising class of electrocatalysts for polymer electrolyte fuel cells (PEFCs) and will also open great opportunities for other electrochemical energy systems, catalysis, and sensors. The commercialization of PEFCs encounters three critical obstacles, viz., high cost, insufficient activity, and inadequate long-term durability. Besides others, the sluggish kinetics of the ORR and alcohol oxidation and insufficient catalyst stability are important reasons for these obstacles. Various approaches have been taken to overcome these obstacles, e.g., by controlling the catalyst particle size in an optimized range, forming multimetallic catalysts, controlling the surface compositions, shaping the catalysts into nanocrystals, and designing supportless catalysts with extended surfaces such as nanostructured thin films, nanotubes, and porous nanostructures. These efforts have produced plenty of excellent electrocatalysts, but the development of multisynergetic functional catalysts exhibiting low cost, high activity, and high durability still faces great challenges. In this Account, we demonstrate that the sol-gel process represents a powerful "bottom-up" strategy for creating nanostructured materials that tackles the problems mentioned above. Aerogels are unique solid materials with ultralow densities, large open pores, and ultimately high inner surface areas. They magnify the specific properties of nanomaterials to the macroscale via self-assembly, which endow them with superior properties. Despite numerous investigations of metal oxide aerogels, the investigation of metal aerogels is in the early stage. Recently, aerogels including Fe, Co, Ni, Sn, and Cu have been obtained by nanosmelting of hybrid polymer-metal oxide aerogels. We report here exclusively on mono-, bi- and multimetallic noble metal aerogels consisting of Ag, Au, Pt, and Pd and their application as electrocatalysts. PMID:25611348

  20. DWPF Hydrogen Generation Study-Form of Noble Metal SRAT Testing

    SciTech Connect

    Bannochie, C

    2005-09-01

    The Defense Waste Processing Facility, DWPF, has requested that the Savannah River National Laboratory, SRNL, investigate the factors that contribute to hydrogen generation to determine if current conservatism in setting the DWPF processing window can be reduced. A phased program has been undertaken to increase understanding of the factors that influence hydrogen generation in the DWPF Chemical Process Cell, CPC. The hydrogen generation in the CPC is primarily due to noble metal catalyzed decomposition of formic acid with a minor contribution from radiolytic processes. Noble metals have historically been added as trim chemicals to process simulations. The present study investigated the potential conservatism that might be present from adding the catalytic species as trim chemicals to the final sludge simulant versus co-precipitating the noble metals into the insoluble sludge solids matrix. Two sludge simulants were obtained, one with co-precipitated noble metals and one without noble metals. Co-precipitated noble metals were expected to better match real waste behavior than using trimmed noble metals during CPC simulations. Portions of both sludge simulants were held at 97 C for about eight hours to qualitatively simulate the effects of long term storage on particle morphology and speciation. The two original and two heat-treated sludge simulants were then used as feeds to Sludge Receipt and Adjustment Tank, SRAT, process simulations. Testing was done at relatively high acid stoichiometries, {approx}175%, and without mercury in order to ensure significant hydrogen generation. Hydrogen generation rates were monitored during processing to assess the impact of the form of noble metals. The following observations were made on the data: (1) Co-precipitated noble metal simulant processed similarly to trimmed noble metal simulant in most respects, such as nitrite to nitrate conversion, formate destruction, and pH, but differently with respect to hydrogen generation: (A) The peak hydrogen generation rate occurred three to five hours later for the regular and heat-treated co-precipitated noble metal slurries than for the slurries with trimmed noble metals. (B) The peak hydrogen generation rate was lower during processing of the co-precipitated noble metal simulant relative to the trimmed noble metal simulant data. (C) Trimmed noble metals appeared to be conservative relative to co-precipitated noble metals under the conditions of these tests as long as the peak hydrogen generation rate occurred early in the SRAT boiling period. (2) If the peak hydrogen generation rate with trimmed noble metals is near or above the DWPF limit, and if the peak occurs late in the SRAT cycle, then a potential SME cycle hydrogen generation rate issue could be anticipated when using co-precipitated noble metals, since the peak is expected to be delayed relative to trimmed noble metals. (3) The peak hydrogen generation rate increased from about 1.3 to about 3.7 lbs H{sub 2}/hr on the range of 170-190% stoichiometry, or about 0.1 lbs. H{sub 2}/hr per % change in the stoichiometric factor at DWPF scale. (4) The peak generation rate was slightly higher during processing of the heat-treated coprecipitated noble metal simulant relative to the trimmed noble metal heat-treated simulant, but this probably due to somewhat more excess acid being added to the co-precipitated noble metal test than intended. (5) The variations in the peak hydrogen generation rate appeared to track the quantity of dissolved rhodium in the SRAT product. (6) A noble metal apparently activated and then de-activated during the final hour of formic acid addition. The associated peak generation rate was <3% of the maximum rate seen in each test. Palladium may have been responsible based on literature data. (7) Planned comparisons between heat-treated and un-heat-treated simulants were complicated by the significantly altered base equivalents following heat-treatment. This necessitated making small adjustments to the stoichiometric acid factor to attempt to match the excess acid contents