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. Noble Gases

    NASA Astrophysics Data System (ADS)

    Podosek, F. A.

    2003-12-01

    The noble gases are the group of elements - helium, neon, argon, krypton, xenon - in the rightmost column of the periodic table of the elements, those which have "filled" outermost shells of electrons (two for helium, eight for the others). This configuration of electrons results in a neutral atom that has relatively low electron affinity and relatively high ionization energy. In consequence, in most natural circumstances these elements do not form chemical compounds, whence they are called "noble." Similarly, much more so than other elements in most circumstances, they partition strongly into a gas phase (as monatomic gas), so that they are called the "noble gases" (also, "inert gases"). (It should be noted, of course, that there is a sixth noble gas, radon, but all isotopes of radon are radioactive, with maximum half-life a few days, so that radon occurs in nature only because of recent production in the U-Th decay chains. The factors that govern the distribution of radon isotopes are thus quite different from those for the five gases cited. There are interesting stories about radon, but they are very different from those about the first five noble gases, and are thus outside the scope of this chapter.)In the nuclear fires in which the elements are forged, the creation and destruction of a given nuclear species depends on its nuclear properties, not on whether it will have a filled outermost shell when things cool off and nuclei begin to gather electrons. The numerology of nuclear physics is different from that of chemistry, so that in the cosmos at large there is nothing systematically special about the abundances of the noble gases as compared to other elements. We live in a very nonrepresentative part of the cosmos, however. As is discussed elsewhere in this volume, the outstanding generalization about the geo-/cosmochemistry of the terrestrial planets is that at some point thermodynamic conditions dictated phase separation of solids from gases, and that the Earth and the rest of the inner solar were made by collecting the solids, to the rather efficient exclusion of the gases. In this grand separation the noble gases, because they are noble, were partitioned strongly into the gas phase. The resultant generalization is that the noble gases are very scarce in the materials of the inner solar system, whence their common synonym "rare gases."This scarcity is probably the most important single feature to remember about noble-gas cosmochemistry. As illustration of the absolute quantities, for example, a meteorite that contains xenon at a concentration of order 10 -10 cm3STP g -1 (4×10-15 mol g-1) would be considered relatively rich in xenon. Yet this is only 0.6 ppt (part per trillion, fractional abundance 10-12) by mass. In most circumstances, an element would be considered efficiently excluded from some sample if its abundance, relative to cosmic proportions to some convenient reference element, were depleted by "several" orders of magnitude. But a noble gas would be considered to be present in quite high concentration if it were depleted by only four or five orders of magnitude (in the example above, 10-10 cm3STP g-1 of xenon corresponds to depletion by seven orders of magnitude), and one not uncommonly encounters noble-gas depletion of more than 10 orders of magnitude.The second most important feature to note about noble-gas cosmochemistry is that while a good deal of the attention given to noble gases really is about chemistry, traditionally a good deal of attention is also devoted to nuclear phenomena, much more so than for most other elements. This feature is a corollary of the first feature noted above, namely scarcity. A variety of nuclear transmutation processes - decay of natural radionuclides and energetic particle reactions - lead to the production of new nuclei that are often new elements. Most commonly, the quantity of new nuclei originating in nuclear transmutation is very small compared to the quantity already present in the sample in question,

  5. Noble gases in meteorites

    Microsoft Academic Search

    Donald D. Bogard

    1971-01-01

    The measurement of isotopic abundances of the noble gases in meteorites and other extraterrestrial samples became a large and active field during the past decade, especially within the last four years. The five stable noble gases proved to be excellent keys for unlocking the secrets of past physical events in the solar system and are used in studies of such

  6. 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.

  7. Viscosity cross sections for the heavy noble gases

    NASA Astrophysics Data System (ADS)

    McEachran, Robert P.; Stauffer, Allan Daniel

    2015-04-01

    We have calculated viscosity cross sections for argon, krypton and xenon from zero to 1 keV using the phase shifts from our previous publication [R.P. McEachran, A.D. Stauffer, Eur. Phys. J. D 68, 153 (2014)] which presented total elastic and momentum transfer cross sections for these gases. As previously, we present simple analytic fits to our results to aid in modelling plasmas containing these atoms. By using the current results and those in reference [R.P. McEachran, A.D. Stauffer, Eur. Phys. J. D 68, 153 (2014)] the first two `partial cross sections' used in the general moment method of solving the Boltzmann equation can be obtained. The agreement of our viscosity cross sections with experimentally derived results indicates the overall reliability of our calculations.

  8. MRI using hyperpolarized noble gases

    Microsoft Academic Search

    H.-U. Kauczor; R. Surkau; T. Roberts

    1998-01-01

    .   The aim of this study was to review the physical basis of MRI using hyperpolarized noble gases as well as the present status\\u000a of preclinical and clinical applications. Non-radioactive noble gases with a nuclear spin 1\\/2 (He-3, Xe-129) can be hyperpolarized\\u000a by optical pumping. Polarization is transferred from circularly polarized laser light to the noble-gas atoms via alkali-metal\\u000a vapors

  9. 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.

  10. 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.

  11. MRI using hyperpolarized noble gases.

    PubMed

    Kauczor, H; Surkau, R; Roberts, T

    1998-01-01

    The aim of this study was to review the physical basis of MRI using hyperpolarized noble gases as well as the present status of preclinical and clinical applications. Non-radioactive noble gases with a nuclear spin 1/2 (He-3, Xe-129) can be hyperpolarized by optical pumping. Polarization is transferred from circularly polarized laser light to the noble-gas atoms via alkali-metal vapors (spin exchange) or metastable atoms (metastability exchange). Hyperpolarization results in a non-equilibrium polarization five orders of magnitude higher than the Boltzmann equilibrium compensating for the several 1000 times lower density of noble gases as compared with liquid state hydrogen concentrations in tissue and allows for short imaging times. Hyperpolarization can be stored sufficiently long (3 h to 6 days) to allow for transport and application. Magnetic resonance systems require a broadband radio-frequency system - which is generally available for MR spectroscopy - and dedicated coils. The hyperpolarized gases are administered as inhalative "contrast agents" allowing for imaging of the airways and airspaces. Besides the known anesthetic effect of xenon, no adverse effects are observed in volunteers or patients. Pulse sequences are optimized to effectively use the non-renewable hyperpolarization before it decays or is destroyed, using fast low-flip-angles strategies to allow for dynamic/breath-hold imaging of highly diffusible (He) or soluble (Xe) gases with in vivo T1-times well below 1 min. Since helium is not absorbed in considerable amounts, its application is restricted to the lung. Xe-129 is also under investigation for imaging of white matter disease and functional studies of cerebral perfusion. Magnetic resonance imaging using hyperpolarized gases is emerging as a technical challenge and opportunity for the MR community. Preliminary experience suggests potential for functional imaging of pulmonary ventilation and cerebral perfusion. PMID:9601972

  12. New pulsed and CW laser lines in the heavy noble gases

    Microsoft Academic Search

    GARY J. LINFORD

    1973-01-01

    Further results obtained with a modified conventional laser tube design are reported. Laser oscillation in both the visible and the middle infrared regions of the spectrum was obtained with this device. Nine new pulsed and CW infrared laser lines in neutral argon, krypton, and xenon were obtained and identified. All the visible laser lines observed corresponded to known noble gas

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

    Microsoft Academic Search

    N. Thonnard

    1995-01-01

    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

  14. Terahertz pulse generation from noble gases

    SciTech Connect

    Chen Yunqing; Yamaguchi, Masashi; Wang Mingfeng; Zhang, X.-C. [Center for Terahertz Research, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2007-12-17

    Terahertz pulse generation in the laser-induced plasma from a series of noble gases (He, Ne, Ar, Kr, and Xe) was systematically investigated. Femtosecond laser pulses consisting of both a fundamental and its second-harmonic frequency were used for the terahertz generation. Experimental results reveal that terahertz generation efficiency of these noble gases increases with decreasing ionization potential.

  15. Light Collection in Liquid Noble Gases

    SciTech Connect

    McKinsey, Dan [Yale University

    2013-05-29

    Liquid noble gases are increasingly used as active detector materials in particle and nuclear physics. Applications include calorimeters and neutrino oscillation experiments as well as searches for neutrinoless double beta decay, direct dark matter, muon electron conversion, and the neutron electric dipole moment. One of the great advantages of liquid noble gases is their copious production of ultraviolet scintillation light, which contains information about event energy and particle type. I will review the scintillation properties of the various liquid noble gases and the means used to collect their scintillation light, including recent advances in photomultiplier technology and wavelength shifters.

  16. Hyperpolarized noble gases as contrast agents.

    PubMed

    Zhou, Xin

    2011-01-01

    Hyperpolarized noble gases ((3)He and (129)Xe) can provide NMR signal enhancements of 10,000 to 100,000 times that of thermally polarized gases and have shown great potential for applications in lung magnetic resonance imaging (MRI) by greatly enhancing the sensitivity and contrast. These gases obtain a highly polarized state by employing a spin exchange optical pumping technique. In this chapter, the underlying physics of spin exchange optical pumping for production of hyperpolarized noble gases is explained and the basic components and procedures for building a polarizer are described. The storage and delivery strategies of hyperpolarized gases for in vivo imaging are discussed. Many of the problems that are likely to be encountered in practical experiments and the corresponding detailed approaches to overcome them are also discussed. PMID:21874479

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. Interaction of laser plasmas with noble gases

    Microsoft Academic Search

    V. E. Levashov; K. N. Mednikov; A. S. Pirozhkov; E. N. Ragozin

    2004-01-01

    The interaction of a noble gas jet (Xe, Kr, He) with a laser plasma at a distance of ?1 cm from a solid target (Mg, (CH2)n, LiF, or CF4) was studied for the first time. The line spectra that were excited in the course of charge exchange of multicharged ions\\u000a with noble gas atoms in the interaction region were recorded.

  4. Fullerenes: A New Carrier Phase for Noble Gases in Meteorites

    NASA Technical Reports Server (NTRS)

    Becker, Luann

    2004-01-01

    The major focus of our research effort has been to measure the noble gases encapsulated within fullerenes, a new carbon carrier phase and compare it to the myriad of components found in the bulk meteorite acid residues. We have concentrated on the carbonaceous chondrites (Allende, Murchison and Tagish Lake) since they have abundant noble gases, typically with a planetary signature that dominates the stepped-release of the meteorite bulk acid residue. They also contain an extractable fullerene component that can be isolated and purified from the same bulk material.

  5. EOSN: A TOUGH2 module for noble gases

    SciTech Connect

    Shan, Chao; Pruess, Karsten

    2003-03-07

    We developed a new fluid property module for TOUGH2, called EOSN, to simulate transport of noble gases in the subsurface. Currently, users may select any of five different noble gases as well as CO2, two at a time. For the three gas components (air and two user-specified noble gases) in EOSN, the Henry's coefficients and the diffusivities in the gas phase are no longer assumed constants, but are temperature dependent. We used the Crovetto et al. (1982) model to estimate Henry's coefficients, and the Reid et al. (1987) correlations to calculate gas phase diffusivities. The new module requires users to provide names of the selected noble gases, which properties are provided internally. There are options for users to specify any (non-zero) molecular weights and half-lives for the gas components. We provide two examples to show applications of TOUGH2IEOSN. While temperature effects are relatively insignificant for one example problem where advection is dominant, they cause almost an order of magnitude difference for the other case where diffusion becomes a dominant process and temperature variations are relatively large. It appears that thermodynamic effects on gas diffusivities and Henry's coefficients can be important for low-permeability porous media and zones with large temperature variations.

  6. 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.

  7. 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.

  8. 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 Astrophysics Data System (ADS)

    Yang, J.; Anders, E.

    1982-06-01

    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.

  9. Fullerenes: An extraterrestrial carbon carrier phase for noble gases

    PubMed Central

    Becker, Luann; Poreda, Robert J.; Bunch, Ted E.

    2000-01-01

    In this work, we report on the discovery of naturally occurring fullerenes (C60 to C400) in the Allende and Murchison meteorites and some sediment samples from the 65 million-year-old Cretaceous/Tertiary boundary layer (KTB). Unlike the other pure forms of carbon (diamond and graphite), fullerenes are extractable in an organic solvent (e.g., toluene or 1,2,4-trichlorobenzene). The recognition of this unique property led to the detection and isolation of the higher fullerenes in the Kratschmer/Huffmann arc evaporated graphite soot and in the carbon material in the meteorite and impact deposits. By further exploiting the unique ability of the fullerene cage structure to encapsulate and retain noble gases, we have determined that both the Allende and Murchison fullerenes and the KTB fullerenes contain trapped noble gases with ratios that can only be described as extraterrestrial in origin. PMID:10725367

  10. Noble gases in chondrites found in hot deserts

    NASA Astrophysics Data System (ADS)

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

    1994-07-01

    Many new meteorites have been recovered from hot desert regions during recent years. These generally heavily weathered chondrites have terrestrial ages up to a few 104 yr, which are younger than those of the less-weathered Antarctic meteorites. We have investigated the influence of weathering on the noble gas record. Concentration and isotopic composition of all noble gases were measured in 30 ordinary chondrites from hot deserts, mainly from the Sahara, the Nullabor Plain, Roosevelt County, and Chile. The results are compared with those of Modern Falls and Antarctic finds respectively. Most of the hot desert chondrite samples contain elevated concentrations of trapped Ar, Kr, and Xe in spite of a preheating at 140 C in-vacuo for 48 hr. Since the isotopic composition of Xe suggests an atmospheric origin, it is concluded that the high concentrations of Kr are also due to a terrestrial contamination. High concentrations of Kr are correlated with low Xe-132/Kr-84 ratios. Finds with high Kr concentrations have ratios of about 0.2, which is higher than the atmospheric value of about 0.04. This implies an elemental fractionation during the trapping process. Stepwise heating experiments show that for strongly weathered meteorites most of the atmospheric Kr is lost after degassing the chondrite for 30 min at 800 C. The treatment of weathered meteorites with acids removes weathering products but does not completely remove the atmospheric gases. Weathering products are not the only carrier of these gases. 'Irreversible adsorption' could be responsible for the incorporation of atmospheric noble gases into other meteoritic mineral grains.

  11. The History of Planetary Degassing as Recorded by Noble Gases

    NASA Astrophysics Data System (ADS)

    Porcelli, D.; Turekian, K. K.

    2003-12-01

    Noble gases provide unique clues to the structure of the Earth and the degassing of volatiles into the atmosphere. Since the noble gases are highly depleted in the Earth, their isotopic compositions are prone to substantial changes due to radiogenic additions, even from scarce parent elements and low-yield nuclear processes. Therefore, noble gas isotopic signatures of major reservoirs reflect planetary differentiation processes that generate fractionations between these volatiles and parent elements. These signatures can be used to construct planetary degassing histories that have relevance to the degassing of a variety of chemical species as well.It has long been recognized that the atmosphere is not simply a remnant of the volatiles that surrounded the forming Earth with the composition of the early solar nebula. It was also commonly thought that the atmosphere and oceans were derived from degassing of the solid Earth over time (Brown, 1949; Suess, 1949; Rubey, 1951). Subsequent improved understanding of the processes of planet formation, however, suggests that substantial volatile inventories could also have been added directly to the atmosphere. The characteristics of the atmosphere therefore reflect the acquisition of volatiles by the solid Earth during formation (see Pepin and Porcelli, 2002; Chapter 4.12), as well as the history of degassing from the mantle. The precise connection between volatiles now emanating from the Earth and the long-term evolution of the atmosphere are key subjects of modeling efforts, and are discussed below.Major advances in understanding the behavior of terrestrial volatiles have been made based upon observations on the characteristics of noble gases that remain within the Earth. Various models have been constructed that define different components and reservoirs in the planetary interior, how materials are exchanged between them, and how the noble gases are progressively transferred to the atmosphere (see Chapter 2.06). While there remain many uncertainties, an overall process of planetary degassing can be discerned. The present chapter discusses the constraints provided by the noble gases and how these relate to the degassing of the volatile molecules formed from nitrogen, carbon, and hydrogen (see also Chapter 3.04). The evolution of particular atmospheric molecular species, such as CO2, that are controlled by interaction with other crustal reservoirs and which reflect surface chemical conditions, are primarily discussed elsewhere (Chapter 8.09).Noble gases provide the most detailed constraints on planetary degassing. A description of the available noble gas data that must be incorporated into any Earth degassing history is provided first in Section 4.11.2, and the constraints on the total extent of degassing of the terrestrial interior are provided in Section 4.11.3. Noble gas degassing models that have been used to describe and calculate degassing histories of both the mantle ( Section 4.11.4) and the crust ( Section 4.11.5) are then presented. These discussions then provide the context for an evaluation of major volatile cycles in the Earth ( Section 4.11.6), and speculations about the degassing of the other terrestrial planets ( Section 4.11.7), Mars and Venus, that are obviously based on much more limited data. The processes controlling mantle degassing are clearly related to the structure of the mantle, as discussed in Section 4.11.4. Further descriptions of mantle noble gas reservoirs and transport processes based upon multi-tracer variations in mantle-derived materials are provided in Chapter 2.06. An important aspect is the origin of planetary volatiles and whether initial incorporation was into the solid Earth or directly to the atmosphere; these issues are discussed in detail in Chapter 4.12. Basic noble gas elemental and isotopic characteristics are given in Ozima and Podosek (2001) and Porcelli et al. (2002). The major nuclear processes that produce noble gases within the solid Earth, and the half-lives of the major parental nuclides, are given in Table 1. Table 1. Major

  12. Nuclear magnetic resonance imaging with hyper-polarized noble gases

    SciTech Connect

    Schmidt, D.M.; George, J.S.; Penttila, S.I.; Caprihan, A.

    1997-10-01

    This is the final report of a six-month, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The nuclei of noble gases can be hyper polarized through a laser-driven spin exchange to a degree many orders of magnitude larger than that attainable by thermal polarization without requiring a strong magnetic field. The increased polarization from the laser pumping enables a good nuclear magnetic resonance (NMR) signal from a gas. The main goal of this project was to demonstrate diffusion-weighted imaging of such hyper-polarized noble gas with magnetic resonance imaging (MRI). Possible applications include characterizing porosity of materials and dynamically imaging pressure distributions in biological or acoustical systems.

  13. Ring whirl radiative structures after laser breakdown in noble gases

    SciTech Connect

    Filippov, A. V.; Mazalov, D. A.; Pal', A. F.; Rasskazova, V. V.; Rogachev, V. G.; Starostin, A. N.; Shaporenko, A. M. [Troitsk Institute for Innovation and Fusion Research, TRINITI, 142092, Troitsk, Moscow Region (Russian Federation)

    1997-04-15

    It was found experimentally that after breakdown of Q-switched Nd-YAG laser beam in noble gases the toroidal radiative formations shaped from initial spherical region of hot luminous gas. Schlieren and interferometric examinations reveal the existence of nonuniformity in energy input at early spark stage and following formation of the whirl ring structure after the produced shock wave has gone away. The results of numerical modelling of gas dynamical flow arising in Ar after inhomogeneous energy input imitating laser breakdown in real conditions are in qualitative agreement with the observed picture.

  14. Sorption of noble gases by solids, with reference to meteorites. III. Sulfides, spinels, and other substances; on the origin of planetary gases

    NASA Astrophysics Data System (ADS)

    Yang, Jongmann; Anders, Edward

    1982-06-01

    To simulate trapping of noble gases by meteorites, we reacted 15 FeCr or FeCrNi alloy samples with CO, H 2O or H 2S at 350-720 K, in the presence of noble gases. The reaction products, including (Fe,Cr) 2O 3, FeCr 2S 4, FeS, C, and Fe 3C, were analyzed by mass spectrometry, usually after chemical separation by selective solvents. Three carbon samples were prepared by catalytic decomposition of CO or by dehydration of carbohydrates with H 2SO 4. The spinel and carbon samples were similar to those of earlier studies (Yang et al., 1982 and Yang and Anders, 1982), with only minor effects attributable to the presence of Ni. All samples sorted substantial amounts of noble gases, with distribution coefficients of 10 -1-10 -2 cm 3 STP/g atm for Xe. On the basis of release temperature three gas components were distinguished: a generally dominant physisorbed component (20-80% of total), and two more strongly bound, chemisorbed and trapped components. Judging from the elemental pattern, the adsorbed components were acquired at the highest noble gas partial pressure encountered by the sample - atmosphere or synthesis vessel. Sulfides, particularly daubréelite, showed three distinctive trends relative to chromite or magnetite: the high- T component was larger, 30-70% of the total; Ne/Xe ratios were higher, by up to 10 2, possibly due to preferential diffusion of Ne during synthesis. In one synthesis, at relatively high P, the gases were sorbed with only minimal elemental fractionation, presumably by occlusion. Most of the features of primordial noble gases can be explained in terms of the data and concepts presented in the three papers of this series. The elemental fractionation pattern of Ar, Kr, Xe in meteorites, terrestrial rocks, and planets resembles the adsorption pattern on the solids studied: carbon, spinels, Sulfides, etc. The variation in Ne/Ar ratio may be explained by preferential diffusion of Ne. The high release temperature of meteoritic noble gases may be explained by transformation of physisorbed to chemisorbed gas, as observed in some experiments. The ready loss of meteoritic heavy gases on surficial oxidation ("Phase Q") is consistent with adsorption, as is the high abundance. Extrapolation of the limited laboratory data suggests that the observed amounts of noble gases could have been adsorbed from a solar gas at 160-170 K and 10 -6-10 -5 atm, i.e. in the early contraction stages of the solar nebula. The principal unsolved problem is the origin of isotopically anomalous, apparently mass-fractionated noble gases in the Earth's atmosphere and in meteoritic carbon and chromite.

  15. 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.

  16. 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.

  17. 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.

  18. Carbon, Nitrogen, and Noble Gases in the Diamond Fractions of the Novo Urei Ureilite

    NASA Astrophysics Data System (ADS)

    Fisenko, A. V.; Verchovsky, A. B.; Semjonova, L. F.; Pillinger, C. T.

    2004-09-01

    We measured the contents and isotopic compositions for C, N, and noble gases in the diamond fractions separated in a heavy liquid (? = 2.9 g/cm3) from a sample enriched with diamond from the Novo Urei ureilite. The results show that the concentrations of nitrogen and noble gases in the diamond fraction isolated from the supernatant (the fraction is named DNU-1) are more than a factor of 1.5 higher than those in the diamond fraction from the residue (DNU-2). This difference is probably caused by smaller sizes of grains and (or) clusters of smaller grains as well as by larger defectiveness of the crystal lattice of the diamond in the DNU-1 fraction as compared to DNU-2. Both fractions are similar in the isotopic composition of C and N and in the ratios of trapped chemical elements. The results obtained and the published data concerning C, N, and noble gases in different fractions of other ureilites allow us to conclude the following. (1) The ureilite diamond was most likely formed from graphite and the fine-grained crystalline (or semiamorphous) carbonaceous phase as a result of shock transformation in the parent bodies. (2) The negative result in the search for the isotopically light component of nitrogen (?15N is about -100‰) in the Antarctic unshocked ureilite ALH 78019 (Rai et al., 2002), which introduced serious difficulties for explaining the origin of the ureilite diamond in the parent bodies during the impact, is most likely caused by the absorption of atmospheric nitrogen by the carbonaceous material in the processes of terrestrial weathering. (3) The source of light nitrogen (?15N ~ -100‰) in the ureilite diamond was probably the presolar diamond in the initial carbonaceous material of the ureilite parent bodies, because the impurity elements, including nitrogen (?15N < -350‰), in this diamond could be trapped in the magmatic processes by the carbonaceous material, which became a precursor of the ureilite diamond in the shock event.

  19. Highly concentrated nebular noble gases in porous nanocarbon separates from the Saratov (L4) meteorite

    SciTech Connect

    Amari, Sachiko [McDonnell Center for the Space Sciences and the Physics Department, Washington University, St. Louis, MO 63130 (United States); Matsuda, Jun-ichi [Department of Earth and Space Science, Osaka University, Osaka 560-0043 (Japan); Stroud, Rhonda M. [Code 6360, Naval Research Laboratory, Washington, DC 20375 (United States); Chisholm, Matthew F., E-mail: sa@wuphys.wustl.edu [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2013-11-20

    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 {sup 132}Xe concentration of 2.1 × 10{sup –6} cm{sup 3} STP g{sup –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 (6:10{sup 9}) 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.

  20. Delayed Higher-Order Optical Nonlinearities in Noble Gases

    NASA Astrophysics Data System (ADS)

    Tarazkar, Maryam; Romanov, Dmitri; Levis, Robert

    2014-05-01

    The role of higher-order Kerr effect (HOKE) in femtosecond laser filamentation is currently at the center of a controversy, as alleged crossover from positive to negative nonlinear refractive index at higher intensities was proposed to cause filament stabilization. Experimental evidence of HOKE crossover or lack thereof is being hotly debated. Motivated by this debate, we report the frequency-dependent nonlinear refractive index coefficients n2 and n4 for a series of atmospheric-pressure noble gases: helium, neon, argon, krypton, and xenon. The corresponding atomic hyperpolarizability coefficients are obtained via auxiliary static electric field approach developed on the basis of ab initio calculations implemented in Dalton program and performed at the CCSD level of theory with t-Aug-cc-PV5Z basis set. The n4 index is obtained using the relations between the degenerate six-wave mixing coefficient and some other frequency-dependent second hyperpolarizability coefficients, which can be calculated on the basis of n2via the auxiliary field approach. For all the investigated gases, the n4 indices are found to be positive over the wavelength range 300 nm-1500 nm. This result runs counter to the HOKE crossover hypothesis. The calculated n4 indices demonstrate considerable temporal dispersion, which progressively increases from helium to xenon. This feature implies delayed nonlinearity and calls for modifications in current theoretical models of filamentation process. We gratefully acknowledge financial support through AFOSR MURI Grant No. FA9550-10-1-0561.

  1. Intercomparison of tritium and noble gases analyses, 3 and derived parameters excess air and recharge temperature

    E-print Network

    Intercomparison of tritium and noble gases analyses, 3 H/3 He ages and derived parameters excess with the tritium­helium (3 H/3 He) method has become a powerful tool for hydrogeologists. The uncertainty in the inter- comparison for tritium analyses and ten laboratories participated in the noble gas

  2. Noble gases in 'phase Q' - Closed-system etching of an Allende residue

    NASA Technical Reports Server (NTRS)

    Wieler, Rainer; Baur, Heinrich; Signer, Peter; Anders, Edward; Lewis, Roy S.

    1991-01-01

    Results are presented from an analysis, in nearly pure form, of noble gases from the 'phase-Q' in an HF/HCl residue of the Allende C3V meteorite, using the closed-system stepped etching technique developed by Wieler et al. (1986) and Benkert et al. (1988) to extract noble gases from the residue. The results yield precise values of element and isotope abundances of all five noble gases in phase-Q, which is the major carrier of the planetary gases in carbonaceous chondrites. It was found that Ne-Q and Xe-Q in Allende are very similar to trapped gases in ureilites and in oxidizable carriers in several classes of ordinary chandrites, indicating that Q-gases are present in the formation locations of all these meteorites.

  3. The fractionation of noble gases in diamonds of CV3 Efremovka chondrite

    NASA Technical Reports Server (NTRS)

    Fisenko, A. V.; Verchovsky, A. B.; Semjonova, L. F.; Shukolyukov, Yu. A.

    1993-01-01

    It was shown that in diamonds of Efremovka CV3 the noble gases with normal isotopic compositions are fractionated in different degree while the correlation of isotopic anomalous components is nearly constant. Some data for noble gases in DE-4 sample of Efremovka chondrite are considered. In contrast to DE-2 sample the DE-4 was treated except conc. HClO4, 220 C in addition with mixture of conc. H2SO4+H3PO4 (1:1), 220 C, twice. Noble gases analysis were performed in Germany at Max Plank Institute fur Chemie. Noble gases were released by oxidation of samples at stepped heating from 420 C to 810 C and by pyrolysis at 580, 590, and 680 C.

  4. B-spline calculations of oscillator strengths in noble gases

    NASA Astrophysics Data System (ADS)

    Zatsarinny, Oleg; Bartschat, Klaus

    2009-05-01

    B-spline box-based multi-channel calculations of transition probabilities in noble gases are reported for energy levels up to n= 12. Energy levels and oscillator strengths for transitions from the p6 ground-state configuration, as well as for transitions between excited states, have been computed in the Breit-Pauli approximation. Individually optimized, term-dependent sets of non-orthogonal valence orbitals are used to account for the strong term dependence in the one-electron orbitals. The agreement in the length and velocity gauges of the transition data and the accuracy of the binding energies are used to estimate the accuracy of our results, which are also compared with experimental and other theoretical data. It is shown that the present method can be used for accurate calculations of oscillator strengths for states with intermediate to high n-values, for which it is difficult to apply standard multi-configuration Hartree-Fock (MCHF) methods. Recent developments based on the extension of our computer codes from the semi-relativistic Breit-Pauli Hamiltonian to the full relativistic Dirac-Breit Hamiltonian are also reported.

  5. 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.

  6. 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.

  7. Noble Gases in Stratospheric Dust Particles: Confirmation of Extraterrestrial Origin

    Microsoft Academic Search

    B. Hudson; G. J. Flynn; P. Fraundorf; C. M. Hohenberg; J. Shirck

    1981-01-01

    Noble gas elemental and isotopic ratios were measured in a group of 13 ``chondritic'' stratospheric dust particles. Neon and argon are present in ``solar'' proportions; xenon appears to be dominated by contributions from ``planetary'' sources. The apparent xenon concentration is higher than that measured in any bulk meteorite, approaching the concentration found in the noble gas-rich, acid-insoluble residues from carbonaceous

  8. EOSN - A new TOUGH2 module for simulating transport of noble gases in the subsurface

    SciTech Connect

    Shan, Chao; Pruess, Karsten

    2003-04-02

    Noble gases widely exist in nature, and except for radon, they are stable. Modern techniques can detect noble gases to relatively low concentrations and with great precision. These factors suggest that noble gases can be useful tracers for subsurface characterization. Their applications, however, require an appropriate transport model for data analyses. A new fluid property module, EOSN, was developed for TOUGH2 to simulate transport of noble gases in the subsurface. Currently any of five different noble gases (except radon) as well as CO{sub 2} can be selected, two at a time. For the two selected gas components, the Crovetto et al. (1982) model is used to calculate the Henry's law coefficients; and the Reid et al. (1987) correlation is used to calculate the gas phase diffusivities. Like most other sister modules, TOUGH2/EOSN can simulate nonisothermal multiphase flow and fully coupled transport in fractured porous media. Potential applications of the new module include, but are not limited to: (a) study of different reservoir processes such as recharge, boiling, condensation, and fracture-matrix fluid exchange; (b) characterization of reservoir geometry such as fracture spacing; and (c) analysis of CO{sub 2} sequestration.

  9. 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.

  10. Isotopic measurements of solar noble gases in individual micrometeorites from Greenland and Antarctica

    SciTech Connect

    Olinger, C.T.

    1990-01-01

    Noble gases are studied in individual 100 micron-size particles selected from Greenland and Antarctic glacial sediments. Noble gas isotopic and elemental patterns confirm the extraterrestrial origin of 81 out of 302 particles studied. Micrometeorites in this size range are particularly interesting because they correspond to the peak of the meteoritic mass flux distribution. Many particles studied are compositionally and morphologically similar to known meteoritic materials.

  11. 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 (213 nm) of individual crystals grown from melts at 0.1 GPa 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

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    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 value, it is worth trying to quantify these effects. We have been doing that by looking at the light noble gases: helium, neon, and argon, but these results will have implications for other elements as well. First, isotopic fractionation can occur if the processes which accelerate the SW away from the sun are mass- dependent. It has been uncertain how large this effect might be. In an effort to quantify this effect, Genesis collected samples of SW from different flow regimes (slow, fast, CME). Our measurements of these different regimes have tightly constrained the possible isotopic fractionation of neon and argon. Second, there are implantation effects. It is known that implantation at constant velocity results in mass fractionation with depth. Heavier isotopes have higher energy, and thus a larger range. The effect of this is that if all of the gas is not recovered during the measurement, the measured isotopic ratios will be altered from their source values. Surface erosion (such as surface damage of Genesis collectors and sputtering of lunar regolithic material) will make the measured ratios heavier than the source, while incomplete degassing of the sample will make the measured ratios lighter. And third, thermally activated diffusion can alter the initial depth profiles and cause losses of shallowly implanted species, both of which cause preferential loss of the light isotopes. We are currently working on a diffusion experiment to determine the diffusion parameters of the Genesis collector materials and to quantify the changes in the measured ratios from diffusive losses. We maintained individual pieces of two different Genesis collectors, polished aluminum and aluminum on sapphire (AloS), at six different temperatures between 160 C and 360 C for 322 days. And now we are performing step-wise heating on the samples. Helium and neon are measured together in one mass spectrometer, and Ar is cryogenically separated from them and measured in a second mass spectrometer. Preliminary results show higher variation in 3He/4He than 20Ne/22Ne and little variation in 36Ar/38Ar, as expected.

  13. Seawater-Derived Noble Gases and Halogens Preserved in Peridotite and Eclogite from the Subduction-Type Sanbagawa Metamorphic Belt

    NASA Astrophysics Data System (ADS)

    Sumino, H.; Endo, S.; Wallis, S.; Mizukami, T.; Burgess, R.; Holland, G.; Ballentine, C. J.

    2010-12-01

    Subduction volcanism is generally considered to form a 'subduction barrier' that efficiently recycles volatile components contained in subducted slabs back to the Earth's surface (Staudacher and Allegre, 1988, Earth Planet. Sci. Lett. 89, 173-183). Nevertheless, subduction of sediment and seawater-dominated pore fluids to the deep mantle has been proposed to account for heavy noble gas (Ar, Kr and Xe) non-radiogenic elemental abundance and isotopic pattern of the convecting mantle (Holland and Ballentine, 2006, Nature 441, 186-191). To verify whether and how subduction fluids preserve a seawater signature, we have determined noble gas and halogen compositions of the Higashi-akaishi peridotite and Western Iratsu eclogite bodies in the Sanbagawa metamorphic belt, southwest Japan, in which relicts of slab-derived water are contained as hydrous mineral inclusions in wedge mantle rocks exhumed from depths in excess of 100 km (Mizukami et al., 2004, Nature 427, 432-436) and aqueous fluid inclusions in associated slab-derived eclogites (Endo et al., 2009, J. Metamorphic Geol. 27, 371-384; Endo, 2010, Isl. Arc 19, 313-335). The striking similarities of the observed noble gas and halogen compositions of the Higashi-akaishi peridotite with marine pore fluids (Sumino et al., 2010, Earth Planet. Sci. Lett. 294, 163-172) challenge a popular concept, in which the water flux into the mantle wedge is only by hydrous minerals in altered oceanic crust and sediment (e.g., Schmidt and Poli, 1998, Earth Planet. Sci. Lett. 163, 361-379). The Western Iratsu eclogite also exhibits non-radiogenic noble gas elemental ratios well explained by a mixing between seawater-derived and sedimentary components. These results indicate that subduction and closed system retention of marine pore fluid occurs up to depths of at least 100 km. The subducted halogen and noble gas compositions are clearly distinct from those of arc volcanic gases. This implies that the ultramafic-mafic metamorphic rocks of the Sanbagawa belt appear to have frozen-in and preserved a previously unseen part of the deep water recycling process whereby noble gases and halogens (and probably other volatiles) are injected into the wedge mantle just above the subducting slab, requiring a reassessment of the dominant transport mechanism and source of water in subduction zones. A small proportion of marine pore fluid, preserved in the downgoing hydrous peridotite and/or eclogite, can account for the heavy noble gas composition observed in the convecting mantle.

  14. Biomedical magnetic resonance imaging and spectroscopy with laser polarized noble gases

    SciTech Connect

    Welsh, R.C.; Rosen, M.S.; Coulter, K.P.; Chupp, T.E.; Swanson, S.D.; Agranoff, B.W.; Prince, M.R. [Univ. of Michigan, Ann Arbor, MI (United States)

    1996-05-01

    In the past year, a great deal of attention has been drawn to the use of laser polarized noble gases to produce magnetic resonance images of rodent and human lungs. Initial demonstrations proved the principle that air space images can be produced with noble gases polarized to several percent. (The noble gas density is thousands of times greater than the proton polarization of order 10{sup {minus}5} at 2 Tesla.) The manifold motivations include improvement of pulmonary and circulatory diagnostic radiology techniques as well as study of physiological function including neurological response. The authors have undertaken a program of development and application of MR imaging and spectroscopy using laser polarized gases with several goals including development of techniques and technologies to facilitate research and eventual medical applications. This talk will describe this multi-disciplinary program combining laser and optical physics, magnetic resonance tomography, neurophysiology and medical science.

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

    USGS Publications Warehouse

    Mazor, E.; Truesdell, A.H.

    1984-01-01

    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 and 40Ar) and atmospheric noble gases (Ne, Ar and Kr) suggest the following dynamic model: the geothermal fluids originated from meteoric water that penetrated to more than 2500 m depth (below the level of first boiling) and mixed with radiogenic He and 40Ar formed in the aquifer rocks. Subsequently, small amounts of steam were lost by a Raleigh process (0 - 30%) and mixing with shallow cold water occurred (0 - 30%). Noble gases are sensitive tracers of boiling in the initial stages of 0 - 3% steam separation and complement other tracers, such as C1 or temperature, which are effective only beyond this range. ?? 1984.

  16. 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

  17. 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

    Cold and trapped metastable noble gases Wim Vassen LaserLaB Vrije Universiteit, De Boelelaan 1081, 2012) We review experimental work on cold, trapped metastable noble gases. We emphasize the aspects. These aspects include detection techniques and collision processes unique to metastable atoms. We describe

  18. 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

    Cold and trapped metastable noble gases Wim Vassen LaserLaB Vrije Universiteit, De Boelelaan 1081, 2011) We review experimental and theoretical work on cold, trapped metastable noble gases. We em to metastable atoms. We describe several experiments exploiting these unique features in fields including atom

  19. Seeded optical breakdown of molecular and noble gases

    SciTech Connect

    Polynkin, Pavel; Scheller, Maik; Moloney, Jerome V. [College of Optical Sciences, University of Arizona 1630 E. University Blvd., Tucson, Arizona 85721 (United States)

    2012-07-30

    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.

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

    Microsoft Academic Search

    Boyd Mclean Goodson; Boyd M

    1999-01-01

    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

  1. Nuclear Magnetic Resonance of Laser-Polarized Noble Gases in Molecules, Materials, and Organisms

    Microsoft Academic Search

    Boyd M. Goodson

    2002-01-01

    The sensitivity of conventional nuclear magnetic resonance (NMR) techniques is fundamentally limited by 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

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

    Microsoft Academic Search

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

    2009-01-01

    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

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

    E-print Network

    Mukhopadhyay, Sujoy

    LETTERS 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 the radioactive decay of 40 K is accounted for by the atmosphere and upper mantle5 . However, geophysical6

  4. 10.1098/rsta.2002.1084 On the origin of noble gases in mantle plumes

    E-print Network

    10.1098/rsta.2002.1084 On the origin of noble gases in mantle plumes By Nicolas Coltice1 a n d 2002 The chemical di¬erences 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

  5. H3+ as a sequestrator of noble gases in the outer solar nebula

    Microsoft Academic Search

    O. Mousis; F. Pauzat; Y. Ellinger

    2006-01-01

    Noble gases are an important component of the atomic population in the universe. It is generally admitted that these elements are inert and do not participate in molecular structures, except the puzzling X-halides compounds. However, this statement may not be relevant when positive ions are involved, especially is the case of the interstellar medium where positive ions do exist in

  6. Noble Gases in Ice Cores: Indicators of the Earth's Climate History

    E-print Network

    Winckler, Gisela

    Noble Gases in Ice Cores: Indicators of the Earth's Climate History Gisela Winckler and Jeffrey P of changes in earth's environment over the past 800,000 years. Because ice cores represent continuous. Severinghaus Abstract Polar ice cores constitute excellent archives of past environmental conditions

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

    E-print Network

    Paris-Sud XI, Université de

    for subsequent loss. Doing so, the I-Pu-Xe age of the Earth becomes 50 Ma after start of solar system formation1 The origins and concentrations of water, carbon, nitrogen and noble gases on Earth Bernard Marty@crpg.cnrs-nancy.fr Submitted as a Frontiers article to Earth and Planetary Science Letters revised version, October 10, 2011

  8. TALIF Calibration with Noble Gases for Quantitative Atomic Density Measurements

    Microsoft Academic Search

    K. Niemi; V. Schulz-von der Gathen; H. F. Döbele

    2001-01-01

    In order to obtain absolute atomic ground state densities with two-photon absorption laser-induced fluorescence spectroscopy (TALIF) a reliable calibration technique and the consideration of collisional quenching effects on the induced population are required. A comparative measurement with a noble gas having a two-photon resonance spectrally close to the atomic transition can be used as a calibration. Suitable transitions exist in

  9. Novel MRI Applications of Laser-Polarized Noble Gases

    Microsoft Academic Search

    R. W. Mair; R. L. Walsworth

    2002-01-01

    Gas-phase NMR has great potential as a probe for a variety of interesting physical and biomedical problems that are not amenable to study by water or similar liquid. However, NMR of gases was largely neglected due to the low signal obtained from the thermally-polarized gases with very low sample density. The advent of optical pumping techniques for enhancing the polarization

  10. Trapping and Modification Processes of Noble Gases and Nitrogen in Meteorites and Their Parent Bodies

    NASA Astrophysics Data System (ADS)

    Wieler, R.; Busemann, H.; Franchi, I. A.

    We review the inventories of primordial noble gases and nitrogen in meteorites, their carrier phases, how and where they may have been incorporated, as well as processes modifying their abundances on meteorite parent bodies. Some of the many distinct noble gas and nitrogen components have an isotopic composition very different from that in the Sun. These components reside in presolar grains. "Anomalous" noble gas and nitrogen components thus are used to infer parent stars of presolar grains as well as theories of stellar nucleosynthesis. Other noble gas components have an isotopic signature roughly similar to the solar composition. Some of these "normal" components are also carried by presolar grains and probably approximately represent the average isotopic composition of their parent stars. Carriers of other normal components remain ill-defined and their origin unclear. Their isotopic identity was possibly established in the solar nebula, but it appears increasingly likely that this often also happened earlier somewhere in the presolar molecular cloud. Apart from allowing us to study meteorite formation, primordial noble gases and nitrogen also are important tracers to constrain the metamorphic history of meteorite parent bodies.

  11. Novel MRI applications of laser-polarized noble gases

    Microsoft Academic Search

    R. W. Mair; R. L. Walsworth

    2002-01-01

    Gas-phase nuclear magnetic resonance (NMR) has great potential as a probe for a variety of interesting physical and biomedical\\u000a problems that are not amenable to study by water or similar liquid. However, NMR of gases was largely neglected due to the\\u000a low signal obtained from the thermally polarized gases with very low sample density. The advent of optical pumping techniques

  12. Carbynes: carriers of primordial noble gases in meteorites.

    PubMed

    Whittaker, A G; Watts, E J; Lewis, R S; Anders, E

    1980-09-26

    Five carbynes (triply bonded allotropes of carbon) have been found by electron diffraction in the Allende and Murchison carbonaceous chondrites: carbon VI, VIII, X, XI, and (tentatively) XII. From the isotopic composition of the associated noble-gas components, it appears that the carbynes in Allende (C3V chondrite) are local condensates from the solar nebula, whereas at least two carbynes in Murchison (C2 chondrite) are of exotic, presolar origin. They may be dust grains that condensed in stellar envelopes and trapped isotopically anomalous matter from stellar nucleosynthesis. PMID:17745959

  13. Recharge and source-water insights from the Galapagos Islands using noble gases and stable isotopes

    NASA Astrophysics Data System (ADS)

    Warrier, Rohit B.; Castro, Maria Clara; Hall, Chris M.

    2012-03-01

    Through a combined noble gas and stable isotope study carried out in the Galapagos Islands of Santa Cruz and San Cristobal, we demonstrate the utility of atmospheric noble gases in identifying recharge areas and timing of recharge in fractured, basaltic systems. Timing of recharge obtained through noble gas temperatures (NGTs) for all samples is corroborated by stable isotopes. Except for one sample, combined NGTs and stable isotope analyses point to recharge during the hot season for all low-altitude (<˜420 m) spring samples from San Cristobal and all basal aquifer samples in Santa Cruz. Stable isotope comparisons also indicate that San Cristobal springs located at high altitudes (>420 m above sea level) are recharged during both the "garúa" and hot seasons. Preservation of seasonality independently recorded by NGTs and stable isotopes is further reinforced by estimated young water ages. Samples located at high-altitude display systematic deviations of dissolved noble gases from expected air saturated water values and lead to inconsistent recharge altitudes and temperatures using standard NGT models. Existing degassing models are unable to account for the observed noble gas pattern for most samples. We explore various mechanisms to assess their potential at reproducing the observed noble gas signature. In particular, the potential impact of fog droplets during the cooler "garúa" season on dissolved noble gas concentrations in groundwater and the effect of mixing high-altitude (?1500 m) rainwater with low-altitude (˜400 m) fog droplets is explored. This mixing hypothesis is capable of explaining Ne and Xe concentrations for most high-altitude samples.

  14. 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.

  15. 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.

  16. Tunneling ionization of noble gases in a high-intensity laser field

    SciTech Connect

    Augst, S.; Strickland, D.; Meyerhofer, D.D.; Chin, S.L.; Eberly, J.H. (Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 (US))

    1989-11-13

    Studies of multiphoton ionization of noble gases have been carried out using 1-{mu}m, 1-ps laser pulses with intensities up to the mid- 10{sup 16} W/cm{sup 2}. To our knowledge, this work represents the first study of the production of highly ionized noble-gas ions done exclusively in the tunneling regime. It is found in this regime that the ionization at a given intensity depends on both the ionization potential and the charge state of the species. The onset of ionization occurs when the sum of the Coulomb and laser electric potentials causes the electron to be unbound.

  17. A mass spectrometric system for the analysis of noble gases and tritium from water samples

    Microsoft Academic Search

    Urs Beyerle; Werner Aeschbach-Hertig; Dieter M. Imboden; Heinrich Baur; Thomas Graf; Rolf Kipfer

    2000-01-01

    The design, setup, and performance of a mass spectrometric system for the analysis of noble gas isotopes (³He, ⁴He, ²°Ne, ²¹Ne, ²²Ne, ³⁶Ar, ⁴°Ar, ⁸⁴Kr, ¹³⁶Xe) and tritium (³H) from water samples are described. The ³H concentration is measured indirectly by the ³He ingrowth from radioactive decay. After extraction, purification, and separation, the noble gases are measured in two noncommercial

  18. Electrical conductivity of noble gases at high pressures

    SciTech Connect

    Adams, J. R.; Reinholz, H.; Redmer, R.; Mintsev, V. B.; Shilkin, N. S.; Gryaznov, V. K. [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany) and School of Physics, University of Western Australia, Crawley WA 6009 (Australia); Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany); Institute of Problems of Chemical Physics, Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region (Russian Federation)

    2007-09-15

    Theoretical results for the electrical conductivity of noble gas plasmas are presented in comparison with experiment. The composition is determined within a partially ionized plasma model. The conductivity is then calculated using linear response theory, in which the relevant scattering mechanisms of electrons from ions, electrons, and neutral species are taken into account. In particular, the Ramsauer-Townsend effect in electron-neutral scattering is discussed and the importance of a correct description of the Coulomb logarithm in electron scattering by charged particles is shown. A detailed comparison with recent experiments on argon and xenon plasmas is given and results for helium and neon are also revisited. Excellent agreement between theory and experiment is observed, showing considerable improvement upon previous calculations.

  19. Enhancement of surface NMR by laser-polarized noble gases

    SciTech Connect

    Room, T.; Appelt, S.; Seydoux, R. [Materials Sciences Division, Lawrence Berkeley National Laboratory] [Materials Sciences Division, Lawrence Berkeley National Laboratory; [the Department of Chemistry, University of California, Berkeley, California 94720 (United States); Hahn, E.L. [Materials Sciences Division, Lawrence Berkeley National Laboratory] [Materials Sciences Division, Lawrence Berkeley National Laboratory; [the Department of Chemistry, University of California, Berkeley, California 94720 (United States); [Department of Physics, University of California, Berkeley, California 94720 (United States); Pines, A. [Materials Sciences Division, Lawrence Berkeley National Laboratory] [Materials Sciences Division, Lawrence Berkeley National Laboratory; [the Department of Chemistry, University of California, Berkeley, California 94720 (United States)

    1997-05-01

    The transfer of spin polarization from laser-polarized helium and xenon to spins such as {sup 1}H and {sup 13}C on the surface of high-surface-area solids (Aerosil) is demonstrated over a temperature range from 4 to 200 K. The transfer mechanism is dipole-dipole cross relaxation between the spins of the adsorbed mobile noble gas and the surface spins (spin-polarization-induced nuclear Overhauser effect). The enhancement of surface proton magnetization by laser-polarized helium at 4 K and 10 K is between one and twofold. Using laser-polarized xenon, enhancement factors of up to 20 were obtained when compared to the Boltzmann polarization in a field of 4.2 T and at a temperature of 130 K. {copyright} {ital 1997} {ital The American Physical Society}

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

    E-print Network

    Guillot, B

    2011-01-01

    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 compositions. 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. With all melt composition investigate...

  1. Anomalous Ne enrichment in obsidians and Darwin glass: Diffusion of noble gases in silica-rich glasses

    Microsoft Academic Search

    Jun-Ichi Matsuda; Kayo Matsubara; Haruaki Yajima; Koshi Yamamoto

    1989-01-01

    We have determined noble gas concentrations in seven obsidians and a Darwin glass by stepwise heating. The pattern of noble gases relative to air showed that Ne was enriched in most of the obsidians and Darwin glass. The release temperatures of Ne were 400-500°C. The occurrence of Ne excess in Darwin glass and related impact glasses can be explained by

  2. Adsorption behavior of ternary mixtures of noble gases inside single-walled carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Foroutan, Masumeh; Nasrabadi, Amir Taghavi

    2010-09-01

    In order to study the gas-storage and gas-filtering capability of carbon nanotube (CNT) bundles simultaneously, we considered the adsorption behavior of a ternary mixture of noble gases, including Argon (Ar), Krypton (Kr), and Xenon (Xe), i.e., Ar-Kr-Xe mixture, on (10, 10) single-walled carbon nanotube (SWCNT) bundles. Molecular dynamics (MD) simulations at different temperatures of (75, 100, 150, 200, 250, and 300) K were performed, and adsorption energies, self-diffusion coefficients, activation energies, and radial distribution functions (RDFs) were computed to analyze the thermodynamics, transport and structural properties of the adsorption systems. It is observed that the SWCNT bundles have larger contents of heavier noble gases compared to the lighter ones. This interesting behavior of SWCNT bundles makes them proper candidates for gas-storage and gas molecular-sieving processes.

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

    PubMed

    Goodson, Boyd M

    2002-04-01

    The sensitivity of conventional nuclear magnetic resonance (NMR) techniques is fundamentally limited by 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 review describes the principles and magnetic resonance applications of laser-polarized noble gases. The enormous sensitivity enhancement afforded by optical pumping can be exploited to permit a variety of novel NMR experiments across numerous 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, NMR sensitivity enhancement via polarization transfer, and low-field NMR and MRI. PMID:12036331

  4. Noble gases in the Finero phlogopite-peridotites, western Italian Alps

    Microsoft Academic Search

    Takuya Matsumoto; Tomoaki Morishita; Jun-Ichi Matsuda; Toshiyuki Fujioka; Masamichi Takebe; Koshi Yamamoto; Shoji Arai

    2005-01-01

    Here we report results from an investigation of noble gases in a specimen with layers of very fine-grained apatite and orthopyroxene from the Finero ultramafic complex, western Italian alps. We have also examined fresh olivine grains separated from phlogopite-harzburgites without an apatite layer. Fluid inclusions of these olivine separates appeared rich in radiogenic components such as 4He, 21Ne and 40Ar,

  5. Quenching of metastable He/sup +/(2s) ions in collision with noble gases

    SciTech Connect

    Gupta, G.P.; Mathur, K.C.

    1980-04-01

    A two-state theory is used to obtain the quenching cross sections of metastable helium ions in collision with noble gases (He, Ne, Ar, Kr, and Xe). The potentials used in the present calculation are based on information derived from the experimental scattering data by Smith et al. The results for the quenching cross sections are found to be in reasonable agreement with the recent data of Prior and Wang.

  6. Simultaneous measurements of radioactive noble gases and aerosols in the vicinity of a nuclear power station

    NASA Astrophysics Data System (ADS)

    Bjurman, Björn; Erlandsson, Bengt; Mattsson, Sören

    1989-01-01

    Simultaneous measurements of the activity concentration of radioactive noble gases and aerosols have been made in the vicinity of the Swedish nuclear power station at Ringhals. The primary photon fluence rate due to radioactive noble gases in the air was measured with a Ge detector, placed on the ground 4.4 km away from the power station. Surface air was also filtered through Microsorban or glass fibre filters using a high-volume air pump. The filters were changed weekly, and the activity concentration of aerosol-bound radionuclides was measured with a Ge detector. Measurements of the radioactive noble gases show that the Gaussian plume model with standard dispersion parameters can be used to calculate the air concentration within a factor of 2. For aerosols emanating from the nuclear power station the ratios between measured air concentrations and air concentrations calculated from reported releases were about 30 for 60Co and 10 for 140Ba. This discrepancy between measured and calculated air concentrations is probably due to underestimated reported releases, caused by particle size fractionation in the stack of the power plant.

  7. Transient thermal effects in solid noble gases as materials for the detection of Dark Matter

    SciTech Connect

    Lazanu, Ionel [University of Bucharest, Faculty of Physics, POBox MG-11, Bucharest-Magurele (Romania); Lazanu, Sorina, E-mail: ionel.lazanu@g.unibuc.ro, E-mail: lazanu@infim.ro [National Institute of Materials Physics, POBox MG-7, Bucharest-Magurele (Romania)

    2011-07-01

    Noble solid gases are promising detector materials to be used in the search for dark matter. In the present paper a systematic analysis of the transient phenomena associated with the stopping of recoils in noble gases in the solid phase is performed for the first time. The investigated energy range of the recoils corresponds to the elastic scattering of WIMPs from the galactic halo in these materials. A thermal spike model, previously developed by the authors, is extended and applied to solid noble gases. Ionization, scintillation and nuclear energy loss processes are considered and included in the model, as well as the coupling between the subsystems. The development of the temperature pulse in space and time in solid Ar, Kr and Xe is analysed for different energies of the WIMP, and for different initial temperatures of the material. Phase transitions are possible in particular cases. The results of the model could be used as supplementary information in respect to ionization and scintillation, for detection and particle identification.

  8. 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.

  9. Noble gases released by vacuum crushing of EETA 79001 glass

    NASA Technical Reports Server (NTRS)

    Wiens, R. C.

    1988-01-01

    An EETA 79001 glass sample was crushed in a vacuum to observe the gases released. About 15 pct of the total gas concentrations were a mixture of a small amount of SPB-type gas with larger proportions of another air-like component. Less than 5 pct of the SPB gas was released by crushing, while 36-40 pct of the EETV (indigenous) gas was crush-released. The results are consistent with a siting of the EETV component in 10-100 micron vesicles seen in the glass. It is suggested that the SPB component is either in vesicles less than 6 microns in diameter or is primarily sited elsewhere.

  10. High stability breakdown of noble gases with femtosecond laser pulses.

    PubMed

    Heins, A M; Guo, Chunlei

    2012-02-15

    In the past, laser-induced breakdown spectroscopy (LIBS) signals have been reported to have a stability independent of the pulse length in solids. In this Letter, we perform the first stability study of femtosecond LIBS in gases (to our best knowledge) and show a significant improvement in signal stability over those achieved with longer pulses. Our study shows that ultrashort-pulse LIBS has an intrinsically higher stability in gas compared to nanosecond-pulse LIBS because of a deterministic ionization process at work in the femtosecond pulse. Relative standard deviations below 1% are demonstrated and are likely only limited by our laser output fluctuations. This enhanced emission stability may open up possibilities for a range of applications, from monitoring rapid gas dynamics to high-quality broadband light sources. PMID:22344119

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1982-06-01

    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.

  13. Mass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation

    USGS Publications Warehouse

    Hunt, Andrew G.; Stern, Laura; Pohlman, John W.; Ruppel, Carolyn; Moscati, Richard J.; Landis, Gary P.

    2013-01-01

    As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings may presently be dissociating and releasing methane and other gases to the ocean-atmosphere system. A key challenge in assessing the impact of dissociating gas hydrates on global atmospheric methane is the lack of a technique able to distinguish between methane recently released from gas hydrates and methane emitted from leaky thermogenic reservoirs, shallow sediments (some newly thawed), coal beds, and other sources. Carbon and deuterium stable isotopic fractionation during methane formation provides a first-order constraint on the processes (microbial or thermogenic) of methane generation. However, because gas hydrate formation and dissociation do not cause significant isotopic fractionation, a stable isotope-based hydrate-source determination is not possible. Here, we investigate patterns of mass-dependent noble gas fractionation within the gas hydrate lattice to fingerprint methane released from gas hydrates. Starting with synthetic gas hydrate formed under laboratory conditions, we document complex noble gas fractionation patterns in the gases liberated during dissociation and explore the effects of aging and storage (e.g., in liquid nitrogen), as well as sampling and preservation procedures. The laboratory results confirm a unique noble gas fractionation pattern for gas hydrates, one that shows promise in evaluating modern natural gas seeps for a signature associated with gas hydrate dissociation.

  14. Radiative precursors driven by converging blast waves in noble gases

    SciTech Connect

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Swadling, G. F.; Suzuki-Vidal, F.; Hall, G. N.; Khoory, E.; Pickworth, L.; Bland, S. N.; Grouchy, P. de; Skidmore, J.; Suttle, L.; Bennett, M.; Niasse, N. P. L. [Blackett Laboratory, Imperial College London SW7 2BW (United Kingdom)] [Blackett Laboratory, Imperial College London SW7 2BW (United Kingdom); Williams, R. J. R. [Atomic Weapons Establishment, Aldermaston RG7 4PR (United Kingdom)] [Atomic Weapons Establishment, Aldermaston RG7 4PR (United Kingdom); Blesener, K.; Atoyan, L.; Cahill, A.; Hoyt, C.; Potter, W. [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States)] [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States); and others

    2014-03-15

    A detailed study of the radiative precursor that develops ahead of converging blast waves in gas-filled cylindrical liner z-pinch experiments is presented. The experiment is capable of magnetically driving 20?km s{sup ?1} blast waves through gases of densities of the order 10{sup ?5} g cm{sup ?3} (see Burdiak et al. [High Energy Density Phys. 9(1), 52–62 (2013)] for a thorough description). Data were collected for Ne, Ar, and Xe gas-fills. The geometry of the setup allows a determination of the plasma parameters both in the precursor and across the shock, along a nominally uniform line of sight that is perpendicular to the propagation of the shock waves. Radiation from the shock was able to excite NeI, ArII, and XeII/XeIII precursor spectral features. It is shown that the combination of interferometry and optical spectroscopy data is inconsistent with upstream plasmas being in LTE. Specifically, electron density gradients do not correspond to any apparent temperature change in the emission spectra. Experimental data are compared to 1D radiation hydrodynamics HELIOS-CR simulations and to PrismSPECT atomic physics calculations to assist in a physical interpretation of the observations. We show that upstream plasma is likely in the process of being radiatively heated and that the emission from a small percentage of ionised atoms within a cool background plasma dominates the emission spectra. Experiments were carried out on the MAGPIE and COBRA pulsed-power facilities at Imperial College London and Cornell University, respectively.

  15. Radiative precursors driven by converging blast waves in noble gases

    NASA Astrophysics Data System (ADS)

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Swadling, G. F.; Suzuki-Vidal, F.; Hall, G. N.; Khoory, E.; Pickworth, L.; Bland, S. N.; de Grouchy, P.; Skidmore, J.; Suttle, L.; Bennett, M.; Niasse, N. P. L.; Williams, R. J. R.; Blesener, K.; Atoyan, L.; Cahill, A.; Hoyt, C.; Potter, W.; Rosenberg, E.; Schrafel, P.; Kusse, B.

    2014-03-01

    A detailed study of the radiative precursor that develops ahead of converging blast waves in gas-filled cylindrical liner z-pinch experiments is presented. The experiment is capable of magnetically driving 20 km s-1 blast waves through gases of densities of the order 10-5 g cm-3 (see Burdiak et al. [High Energy Density Phys. 9(1), 52-62 (2013)] for a thorough description). Data were collected for Ne, Ar, and Xe gas-fills. The geometry of the setup allows a determination of the plasma parameters both in the precursor and across the shock, along a nominally uniform line of sight that is perpendicular to the propagation of the shock waves. Radiation from the shock was able to excite NeI, ArII, and XeII/XeIII precursor spectral features. It is shown that the combination of interferometry and optical spectroscopy data is inconsistent with upstream plasmas being in LTE. Specifically, electron density gradients do not correspond to any apparent temperature change in the emission spectra. Experimental data are compared to 1D radiation hydrodynamics HELIOS-CR simulations and to PrismSPECT atomic physics calculations to assist in a physical interpretation of the observations. We show that upstream plasma is likely in the process of being radiatively heated and that the emission from a small percentage of ionised atoms within a cool background plasma dominates the emission spectra. Experiments were carried out on the MAGPIE and COBRA pulsed-power facilities at Imperial College London and Cornell University, respectively.

  16. 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.

  17. Determination of optical constants in noble gases through multiphoton ionization measurements

    SciTech Connect

    Ferrell, W.R.; Payne, M.G.; Garrett, W.R.

    1987-06-15

    A multiphoton ionization technique involving third-harmonic generation in phase-matched mixtures of noble gases has been used to make accurate determinations of oscillator strengths for transitions from the ground state to 6s, 6s', 5d, and 7s levels in Xe and to the 5s' level of Kr. The method also allows determinations to be made of the absorption coefficients for third-harmonic photons generated in noble-gas mixtures and the vacuum-uv refractive index for the positively dispersive buffer-gas component of the medium, all in the same experiment. The effects of low concentrations of dimers on refractive indexes are also demonstrated. Results are compared with data from other experimental techniques.

  18. 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.

  19. Calibration of stack monitors for measurement of noble gases in nuclear facilities.

    PubMed

    Kovar, Petr; Dryak, Pavel; Suran, Jiri; Gudelis, Arunas

    2012-09-01

    In nuclear facilities stack monitors are used for the measurement of the volumetric activity of noble gases. Spectrometric measurement is needed because the content of stack effluents is always a mixture of radionuclides. In some nuclear power plants new types of monitors were installed based on HPGe detectors. For efficiency calibration a standard with the radionuclide Xe-127 was developed and calibration curve constructed in the energy range 81 keV-1293 keV. Experiental efficiencies were checked using an MC model. PMID:22424839

  20. Implications of isotopic signatures of noble gases for the origin and evolution of terrestrial atmospheres

    NASA Technical Reports Server (NTRS)

    Rao, A. S. P.

    1987-01-01

    It is contented that the initial quantities of noble gases present in planetesimals were controlled by the sizes and masses of the planets, and fit with a model of successive accretion. The successive accretion model proposed for the origin of terrestrial planets is based upon: (1) the sequence of zones of condensation of solar nebula, (2) the condensation sequence of minerals, iron and nickel in different P-T regimes of the solar nebula, and (3) the sequence in the nucleation of iron cores of the terrestrial planets.

  1. 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.

  2. Heterogeneities from the first 100 million years recorded in deep mantle noble1 gases from the Northern Lau Back-arc Basin2

    E-print Network

    Mukhopadhyay, Sujoy

    compositions. Here we present new high-precision noble15 gas data from gas-rich basalts erupted along mantle throughout Earth's history.41 42 Introduction43 The noble gas compositions of mantle1 Heterogeneities from the first 100 million years recorded in deep mantle noble1 gases from

  3. A theoretical study of the cohesion of noble gases on graphite

    NASA Astrophysics Data System (ADS)

    Bichoutskaia, Elena; Pyper, Nicholas C.

    2008-01-01

    The interactions of the noble gases with a graphene sheet are investigated theoretically. The short range repulsive interaction between the noble gas and each carbon atom is described using Hartree-Fock atomic densities and a local density functional theory with the exchange functional corrected for the finite range of the interaction by introducing a Rae-type correction depending on the effective number of electrons. The long range interactions are introduced as the sum of the Axilrod-Teller triple-dipole interaction plus the dipole-dipole and dipole-quadrupole dispersive attractions damped according to the theory of Jacobi and Csanak. The energy arising from the interactions between the permanent quadrupoles on the carbon atoms with the dipole they induce on the noble gas is negligible, being nonzero only on account of the atomistic structure of graphene. The mobile and delocalized nature of the graphene ? electrons causes the effective number of electrons to be around 500 rather than that of 12 appropriate for a system of entirely localized interactions with individual carbon atoms. Inclusion of the Axilrod-Teller term is required to obtain reliable predictions for the binding energies and equilibrium geometries. Absorption of a noble gas atom is predicted to occur at the site above the center of a six membered ring although this is preferred over two other sites by only about 5meV. The methods presented for generating all the potentials can be applied to derive the interactions between any ion and carbon atom in the wall of a single-walled nanotube. Knowledge of these interactions is required to study the alkali halide nanocrystals encapsulated in single-walled carbon nanotubes of current interest.

  4. 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.

  5. Opacity and conductivity measurements in noble gases at conditions of planetary and stellar interiors.

    PubMed

    McWilliams, R Stewart; Dalton, D Allen; Konôpková, Zuzana; Mahmood, Mohammad F; Goncharov, Alexander F

    2015-06-30

    The noble gases are elements of broad importance across science and technology and are primary constituents of planetary and stellar atmospheres, where they segregate into droplets or layers that affect the thermal, chemical, and structural evolution of their host body. We have measured the optical properties of noble gases at relevant high pressures and temperatures in the laser-heated diamond anvil cell, observing insulator-to-conductor transformations in dense helium, neon, argon, and xenon at 4,000-15,000 K and pressures of 15-52 GPa. The thermal activation and frequency dependence of conduction reveal an optical character dominated by electrons of low mobility, as in an amorphous semiconductor or poor metal, rather than free electrons as is often assumed for such wide band gap insulators at high temperatures. White dwarf stars having helium outer atmospheres cool slower and may have different color than if atmospheric opacity were controlled by free electrons. Helium rain in Jupiter and Saturn becomes conducting at conditions well correlated with its increased solubility in metallic hydrogen, whereas a deep layer of insulating neon may inhibit core erosion in Saturn. PMID:26080401

  6. 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.

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

    NASA Astrophysics Data System (ADS)

    Wacker, J. F.

    1989-06-01

    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.

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

    DOE PAGESBeta

    Moskovitz, Yevgeny; Yang, Hui

    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 distributionmore »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.« less

  9. Trapped Solar Wind Noble Gases, Kr81\\/Kr Exposure Ages and K\\/Ar Ages in Apollo 11 Lunar Material

    Microsoft Academic Search

    P. Eberhardt; J. Geiss; H. Graf; N. Groegler; U. Kraehenbuehl; H. Schwaller; J. Schwarzmueller; A. Stettler

    1970-01-01

    Grain size and etching experiments show that the fine lunar material contains large amounts of trapped solar wind particles. Elemental and isotopic compositions of the noble gases in solar material and in the terrestrial atmosphere are significantly different, except for the Ar36\\/Ar38 and the Kr isotope ratios. Exposure ages of two rocks and of the fine material are between 380

  10. Determination of Two-Photon Absorption Cross-Section of Noble Gases for Calibration of Laser Spectroscopic Techniques

    SciTech Connect

    Rosa, M. I. de la; Perez, C.; Gruetzmacher, K.; Fuentes, L. M. [Departamento de Fisica Teorica, Atomica y Optica, Facultad de Ciencias, Universidad Valladolid, 47071 Valladolid (Spain)

    2008-10-22

    The objective of our work is to apply two-photon polarization spectroscopy as a new calibration method for the determination of two-photon excitation cross-sections of noble gases, like Xe and Kr, which are commonly used for calibrations of MP-LIF techniques in other laboratories.

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

    NASA Astrophysics Data System (ADS)

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

    1985-04-01

    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.

  12. 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.

  13. Testing the noble gas paleothermometer with a yearlong study of groundwater noble gases in an instrumented monitoring well

    NASA Astrophysics Data System (ADS)

    Hall, Chris M.; Castro, M. Clara; Lohmann, Kyger C.; Sun, Tie

    2012-04-01

    We report the results of a yearlong noble gas study conducted in 2008-2009 together with continuous physical and chemical measurements collected in a monitoring well in an aquifer in southern Michigan. Conditions near the water table are correlated with noble gas concentrations, corresponding noble gas temperatures (NGTs), and precipitation events. This yearlong study is the first noble gas field test that has employed natural recharge and in situ monitored conditions, with minimal disturbance of the unsaturated zone. This detailed study demonstrates that significant changes in conditions near the water table can occur over a year that can greatly affect NGTs. Results show that precipitation events are detected within hours at the water table, but a lag in pressure response argues for a long time constant for gas transport within the unsaturated zone. There is strong evidence for the depletion of oxygen near the water table, which affects the noble gas air-saturated water component. During reducing conditions there is evidence for significant noble gas degassing. Rain from the passage of Hurricane Ike caused a significant shift in stable isotope ratios and injection of a large quantity of excess air and likely led to a much more oxygen-rich environment in the soil gas. Although individual models can account for NGTs over portions of the record, no single NGT model can account for all features observed over the entire study. It is likely that the NGT temperature proxy must be viewed as an average of recharge conditions over several years.

  14. Noble gases in presolar diamonds II: Component abundances reflect thermal processing

    NASA Technical Reports Server (NTRS)

    Huss, Gary R.; Lewis, Roy S.

    1994-01-01

    Using the isotopic compositions derived in Huss and Lewis, 1994a, abundances of the P3, HL, and P6 noble-gas components were determined for 15 diamonds separates from primitive chondrites of 8 chondrite classes. Within a meteorite class, the relative abundances of these components correlate with the petrologic subtype of the host meteorite, indicating that metamorphism is primarily responsible for the variations. Relative abundances of P3, HL, and P6 among diamond samples can be understood in terms of thermal processing of a single mixture of diamonds like those now found in CI and CM2 chondrites. With relatively gentle heating, primitive diamonds first lose their low-temperature P3 gases and a 'labile' fraction of the HL component. Mass loss associated with release of these components produces an increase in the HL and P6 content of the remaining diamond relative to unprocessed diamond. Higher temperatures initiate destruction of the main HL carrier, while the HL content of the surviving diamonds remains essentially constant. At the same time, the P6 carrier begins to preferentially lose light noble gases. Meteorites that have experienced metamorphic temperatures greater than or = 650 C have lost essentially all of their presolar diamond through chemical reactions with surrounding minerals. The P3 abundance seems to be a function only of the maximum temperature experienced by the diamonds and thus is independent of the nature of the surrounding environment. If all classes inherited the same mixture of primitive diamonds, then P3 abundances would tie together the metamorphic scales in different meteorite classes. However, if the P3 abundance indicates a higher temperature than do other thermometers applicable to the host meteorite, then the P3 abundance may contain information about heating prior to accretion. Diamonds in the least metamorphosed EH, CV, and CO chondrites seem to carry a record of pre-accretionary thermal processing.

  15. Crustal Noble Gases in Jwaneng Diamonds With Links to Seismic Tomography

    NASA Astrophysics Data System (ADS)

    Honda, M.; Phillips, D.; Harris, J. W.; Yatsevich, I.

    2005-12-01

    Recent seismic tomography studies of the Kaapvaal-Zimbabwe craton of southern Africa reveal distinct seismic velocity profiles at 150 km depth within the diamond stability field, that appear to correlate with differences in diamond paragenesis. Diamond mines with predominantly eclogitic diamond inclusions (e.g. Jwaneng, Orapa, Premier) overlie lithospheric mantle with relatively slow P-wave velocities, whereas localities with predominantly peridotitic diamond inclusions (e.g. Kimberley, Finsch) are associated with faster P-wave velocities at 150 km depth in the mantle. This distinction in P-wave velocities between the two groups can be interpreted in terms of different chemical compositions in the lithospheric mantle (Shirey, S. B. et al., Science 297, 1683-1686, 2002). Thus, the region with slower P-wave velocities could correlate with an oceanic lithospheric component and/or metasomatising fluids introduced by ancient subduction-related processes. In contrast, the region with faster P-wave velocities may reflect mid-Archean mantle depletion events initiated by craton keel formation. As the mantle beneath the Jwaneng mine is characterized by slower P-wave velocities at 150 km depth, our finding of crustal noble gases in Jwaneng diamonds (gem-quality diamond aggregates, this work; and framesites, Honda, M. et al., Chemical Geology 203, 347-358, 2004) appears to be consistent with the tomographic observations. It is noteworthy that early helium work on diamonds from the Orapa mine also showed radiogenic He-enriched 3He/4He ratios, as low as 0.16 R/Ra (Kurz, M. et al., Earth Planet. Sci. Lett. 86, 57-68, 1987), which could indicate the involvement of crustal helium; consistent with our findings from the Jwaneng diamonds. Thus, it is postulated that diamonds from eclogitic mines could clarify whether or not material subducted into the deep mantle retained crustal and atmospheric noble gases, and could quantify the influence of subducted material through time. In contrast, diamonds from the peridotitic mines could contain pristine ancient mantle noble gas compositions at the time of their formation. Verification of our hypothesis will be significant in providing a basis for the reconciliation of geophysical and geochemical observations in terms of mantle structure and mantle geodynamics.

  16. 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

  17. Noble gases in the Oceanic Crust: Preliminary results from ODP Hole 1256D

    NASA Astrophysics Data System (ADS)

    Kurz, M. D.; Curtice, J. M.; IODP Expedition 335 Science Party

    2011-12-01

    Noble gas isotopes and abundance ratios have been extensively used as tracers of oceanic mantle sources and fluxes. Most of the existing data are from seafloor basalt glasses and hydrothermal fluids, and there are very few studies of noble gases in the oceanic crust, which is an important component in global subduction flux estimates. In an effort to determine the relative contributions of mantle, radiogenic, and atmospheric/hydrothermal noble gas components in the ocean crust, we have performed helium, neon and argon measurements on a suite of gabbros and granoblastic dikes collected during IODP Expeditions 312 and 335 to Hole 1256D, a deep crustal borehole drilled into 15 Ma ocean crust formed at the East Pacific Rise during an episode of superfast spreading (>200 mm/yr). All measurements were carried out by coupled vacuum crushing and melting of whole rock samples, in order to determine the distribution of noble gases within the ocean crust. Total helium abundances in the gabbros range from 0.46 to 1.22 micro cc STP/gram, which is 2 to 5 times higher than literature data, all of which are from the slow spreading Southwest Indian Ridge (Kumagai et al., 2003; Moreira et al., 2003). These strikingly higher helium concentrations place constraints on the thermal crustal history (due to rapid helium diffusivity) and are assumed to reflect fundamentally different emplacement/degassing processes within crust formed at a super fast spreading rate. Crushing releases 12-25 % of the total helium in the gabbros demonstrating that most of the helium resides in the solid mineral phases. Contact metamorphosed granoblastic dikes have total helium contents lower than the gabbros (typically ~ 0.15 micro cc STP/gram), but significantly higher than the assumed degassed basaltic protolith, thus suggesting that metamorphism actually adds helium to the crust, an important hypothesis that requires further testing. The helium isotopes obtained by crushing of both the gabbros and granoblastic dikes are dominated by mantle helium, with average 3He/4He = 6.5 ± .2 times atmosphere (Ra). This value is at the low end of the range for normal Pacific MORB helium data and is interpreted to represent the mantle source. 3He/4He values obtained by melting are slightly lower and are consistent with a small radiogenic component, and suggest that helium will be useful for geochronology of the ocean crust. In contrast with the helium isotopic data, neon and argon are dominated by atmospheric isotopic compositions, which is consistent with mineralogical and petrological evidence for extensive alteration of the crust. Crushing in vacuum releases a larger fraction of total neon and argon (28 to 64 %), suggesting that atmospheric/hydrothermal/alteration neon and argon are loosely bound, most likely in secondary alteration minerals. Small mantle argon isotopic components are only found in a few samples, and only during the heating experiments. These data suggest that the atmospheric noble gas components are most likely to be expelled during subduction of the ocean crust.

  18. CANCELLED Molecular dynamics simulations of noble gases in liquidwater: Solvati on structure, self-diffusion, and kinetic isotopeeffect

    SciTech Connect

    Bourg, I.C.; Sposito, G.

    2007-05-25

    Despite their great importance in low-temperaturegeochemistry, self-diffusion coefficients of noble gas isotopes in liquidwater (D) have been measured only for the major isotopes of helium, neon,krypton and xenon. Data on the self-diffusion coefficients of minor noblegas isotopes are essentially non-existent and so typically are estimatedby a kinetic theory model in which D varies as the inverse square root ofthe isotopic mass (m): D proportional to m-0.5. To examine the validityof the kinetic theory model, we performed molecular dynamics (MD)simulations of the diffusion of noble gases in ambient liquid water withan accurate set of noble gas-water interaction potentials. Our simulationresults agree with available experimental data on the solvation structureand self-diffusion coefficients of the major noble gas isotopes in liquidwater and reveal for the first time that the isotopic mass-dependence ofall noble gas self-diffusion coefficients has the power-law form Dproportional to m-beta with 0noble gasisotopes caused by diffusion in ambient liquid water.

  19. 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.

  20. Testing The Noble Gas Paleothermometer With A Year-long Study Of Groundwater Noble Gases In An Instrumented Monitoring Well

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    We report the results of a year-long noble gas study conducted in 2008 and early 2009, together with a wealth of continuous physical and chemical measurements collected in an instrumented monitoring well in the unconfined Glacial Drift aquifer in southern Michigan. Physical and chemical parameters at or near the water table are correlated with noble gas concentrations, corresponding noble gas temperatures (NGTs) and precipitation events. This year-long study is the first noble gas field test that has employed natural recharge, in situ monitored conditions, with minimal disturbance of the unsaturated zone. This study is unprecedented and demonstrates that there can be significant changes in physical and chemical conditions near the water table, over the space of a year, that can have profound effects on noble gas concentrations and hence, NGTs. The year-long record of conditions in the monitoring well show broad seasonal variations in pH, salinity, water temperature and water table depth. Results show that although precipitation events are detected within hours at the water table, there are significant pressure differences that persist for days at the water table, which argues for a very long time constant for gas transport within the unsaturated zone. There is strong evidence for the depletion of oxygen near the water table, which affects the noble gas air saturated water (ASW) component. When strongly reducing conditions prevail, as indicated by ORP, there is evidence for significant noble gas degassing. A major recharge event during the passage of the remnants of Hurricane Ike in the late summer 2008 caused a significant shift in H and O isotope ratios and it injected a large quantity of excess air into the groundwater. Hurricane Ike also appears to have caused a long-term change in the soil gas composition in the unsaturated zone, likely leading to a much more oxygen rich environment. Although individual competing NGT models can account for noble gas concentrations over portions of the record, no single NGT model can consistently account for all features observed over the entire year-long study. It is likely that the NGT temperature proxy must be viewed as an average of significant recharge conditions over the span of several years.

  1. The heavy noble gas composition of the depleted MORB mantle (DMM) and1 its implications for the origin of heterogeneities in the upper mantle2

    E-print Network

    Mukhopadhyay, Sujoy

    1 The heavy noble gas composition of the depleted MORB mantle (DMM) and1 its implications of the ubiquitous presence of atmospheric contamination, the heavy noble gas14 composition of mid ocean ridge compositions in MORBs from the equatorial Mid-Atlantic16 Ridge to characterize the heavy noble gas composition

  2. Coupled noble gas-hydrocarbon evolution of the early Earth atmosphere upon solar UV irradiation

    E-print Network

    Paris-Sud XI, Université de

    Coupled noble gas-hydrocarbon evolution of the early Earth atmosphere upon solar UV irradiation E, the relationship between noble gas photoionization and organic photochemistry has been investigated from efficient that other ionized noble gases trapping and (2) results in a significant enrichment of heavy xenon

  3. Collisional deactivation of Ba 5d7p (3)D1 by noble gases.

    PubMed

    Smedley, John E; Coulter, Sarah K; Felton, Edward J; Zomlefer, Kayla S

    2008-10-01

    Collisional deactivation of the 5d7p (3)D1 state of Ba by noble gases is studied by time- and wavelength-resolved fluorescence techniques. A pulsed, frequency-doubled dye laser at 273.9 nm excites the 5d7p (3)D1 level from the ground state, and fluorescence at 364.1 and 366.6 nm from the 5d7p (3)D1 --> 6s5d (3)D1 and 5d7p (3)D1 --> 6s5d (3)D2 transitions, respectively, is monitored in real time to obtain the deactivation rate constants. At 835 K these rate constants are as follows: He, (1.69 +/- 0.08) x 10(-9) cm(3) s(-1); Ne, (3.93 +/- 0.14) x 10(-10) cm(3) s(-1); Ar, (4.53 +/- 0.15) x 10(-10) cm(3) s(-1); Kr, (4.64 +/- 0.13) x 10(-10) cm(3) s(-1); Xe, (5.59 +/- 0.22) x 10(-10) cm(3) s(-1). From time-resolved 5d7p (3)D1 emission in the absence of noble gas and from the intercepts of the quenching plots, the lifetime of this state is determined to be 100 +/- 1 ns. Using time- and wavelength-resolved Ba emission with a low background pressure of noble gas, radiative lifetimes of several near-resonant states are determined from the exponential rise of the fluorescence signals. These results are as follows: 5d6d (3)D3, 28 +/- 3 ns; 5d7p (3)P1, 46 +/- 2 ns; 5d6d (3)G3, 21.5 +/- 0.8 ns; 5d7p (3)F3, 48 +/- 1 ns. Integrated fluorescence signals are used to infer the relative rate constants for population transfer from the 5d7p (3)D1 state to eleven near-resonant fine structure states. PMID:18636703

  4. 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

    , can be 1 found . This problem has stimulated the investigation of drift velocities in noble gas SIMULATIONS OF ELECTRON DRIFT VELOCITIES INTHE NOBLE GASES AND THEIR MIXTURES A.J. Davies, J. Dutton, C the respective cross-sections of 1 2 Mixtures of noble and molecular gases a r e widely used the gaseous

  5. 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...

  6. Diagnostics of dielectric barrier discharges in noble gases: atmospheric pressure glow and pseudoglow discharges and spatio-temporal patterns

    Microsoft Academic Search

    Ion Radu; Ray Bartnikas; Grzegorz Czeremuszkin; Michael R. Wertheimer

    2003-01-01

    We present experimental results of atmospheric pressure glow discharges (APGD) in a dielectric barrier discharge reactor. These are examined in different noble gases and in the N2\\/O2 system (air and pure N2), under varying experimental conditions (frequency f; gap length d; and electric field intensity E). Discharge diagnostics have been carried out using ultrahigh speed imaging, and synchronous dual-detection of

  7. Isotopic Composition of Trapped and Cosmogenic Noble Gases in Several Martian Meteorites

    NASA Technical Reports Server (NTRS)

    Garrison, Daniel H.; Bogard, Donald D.

    1997-01-01

    Isotopic abundances of the noble gases were measured in the following Martian meteorites: two shock glass inclusions from EET79001, shock vein glass from Shergotty and Y793605, and whole rock samples of ALH84001 and QUE94201. These glass samples, when combined with literature data on a separate single glass inclusion from EET79001 and a glass vein from Zagami, permit examination of the isotopic composition of Ne, Ar, Kr, and Xe trapped from the Martian atmosphere in greater detail. The isotopic composition of Martian Ne, if actually present in these glasses, remains poorly defined. The Ar-40/Ar-36 ratio of Martian atmospheric Ar may be much less than the ratio measured by Viking and possibly as low as approx. 1900. The atmospheric Ar-36/Ar-38 ratio is less than or equal to 4.0. Martian atmospheric Kr appears to be enriched in lighter isotopes by approx. 0.4%/amu compared to both solar wind Kr and to the Martian composition previously reported. The Martian atmospheric Ar-36/Xe-132 and Kr-84/Xe-132 Xe elemental ratios are higher than those reported by Viking by factors of approx. 3.3 and approx. 2.5, respectively. Cosmogenic gases indicate space exposure ages of 13.9 +/- 1 Myr for ALH84001 and 2.7 +/- 0.6 Myr for QUE94201. Small amounts of Ne-21 produced by energetic solar protons may be present in QUE94201, but are not present in ALH84001 or Y793605. The space exposure age for Y793605 is 4.9 +/- 0.6 Myr and appears to be distinctly older than the ages for basaltic shergottites.

  8. 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.

  9. Interfacial storage of noble gases and other trace elements in magmatic systems

    NASA Astrophysics Data System (ADS)

    Pinilla, Carlos; Davis, Sean A.; Scott, Tom B.; Allan, Neil L.; Blundy, Jon D.

    2012-02-01

    Trace elements are widely used to unravel magmatic processes and constrain the chemical differentiation of the Earth. Key to their use is understanding the controls on fractionation between solid and liquid, which hinge on the energetics of trace element incorporation into crystals. At equilibrium most trace elements are incompatible in bulk magmatic minerals because of unfavourable incorporation energies. We use computational methods to explore the role that crystal interfaces can play in trace element incorporation in minerals. We demonstrate that differences between bulk and interface incorporation energies can be very large and lead to concentration differences of many orders of magnitude, consistent with experimental evidence for interface enrichment. By emphasising the importance of adsorption/incorporation at interfaces, we account for the competing effects of bulk equilibrium and interface segregation operating during melting and crystallisation. Computational results are presented for divalent cations and Ar in bulk forsterite, at the {010} surface and at the {100}/{010} stepped grain boundary. For all species studied larger than Mn2 +, segregation to the interface is highly exothermic. We discuss in particular the take-up of noble gases where, in contrast to earlier work, a recent experimental study concluded that argon is highly compatible in mantle minerals. In contrast our calculations indicate bulk Ar solubility is very small and suggests incorporation at mineral interfaces is overwhelmingly favourable.

  10. 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

  11. Recent advances of in vivo magnetic resonance imaging with laser-polarized noble gases

    Microsoft Academic Search

    R. C. Welsh; T. E. Chupp; K. P. Coulter; M. S. Rosen; S. D. Swanson

    1997-01-01

    The field of polarization-based magnetic resonance imaging has expanded rapidly in the past few years. Realization of this new modality of medical imaging is dependent upon the production of large quantities of noble gas. Additionally the noble gas must be delivered to the subject in controlled and efficient manner. The process of delivery must also preserve a large fraction of

  12. 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.

  13. Photoabsorption to Stark Rydberg States of Heavy Noble Gas Atoms: Testing Limits of Closed Orbit Theory

    Microsoft Academic Search

    Heric Flores-Rueda; Matthew L. Keeler; David Wright; Thomas J. Morgan

    2003-01-01

    The selective dramatic effects of a dc electric field on the photoabsorption spectrum of Rydberg states and the associated recurrence strengths and closed orbits are studied in heavy noble gas atoms. Using collinear atom-laser beam spectroscopy, complex scaled-energy photoabsorption spectra are mapped experimentally in high resolution for pi and sigma transitions from the ns[3\\/2] and ns[1\\/2] metastable states, formed by

  14. 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.

  15. Concentrations and isotope ratios of helium and other noble gases in the Earth's atmosphere during 1978-2011

    NASA Astrophysics Data System (ADS)

    Brennwald, Matthias S.; Vogel, Nadia; Figura, Simon; Vollmer, Martin K.; Langenfelds, Ray; Paul Steele, L.; Maden, Colin; Kipfer, Rolf

    2013-03-01

    The evolution of the atmospheric noble gas composition during the past few decades has hardly been studied because, in contrast to many other atmospheric gases, systematic time-series measurements have not been available. Based on theoretical considerations, the atmospheric noble gas isotope composition is assumed to be stable on time scales of up to about 106 yrs, with the potential exception of anthropogenic changes predicted for the He concentration and the 3He/4He ratio. However, experimental assessments of the predicted changes in the atmospheric He isotope composition are controversial. To empirically test these assumptions and predictions, we analysed the noble gas isotope composition in samples of the Cape Grim Air Archive, a well-defined archive of marine boundary layer air in the southern hemisphere. The resulting time series of the 20Ne, 40Ar, 86Kr and 136Xe concentrations and 20Ne/22Ne and 40Ar/36Ar ratios during 1978-2011 demonstrate the stability of the atmospheric Ne, Ar, Kr and Xe composition during this time interval. The He isotope data indicate a decrease in the 3He/4He during the same time interval at a mean rate of 0.23-0.30‰ per yr. This result is consistent with most model predictions of the rate of decrease in the atmospheric 3He/4He ratio associated with mining and burning of fossil fuels.

  16. Scaling law of single ion–atom impact ionization cross sections of noble gases from He to Xe at strong perturbative energies

    NASA Astrophysics Data System (ADS)

    Ren, Ping-Yuan; Zou, Xian-Rong; Shao, Jian-Xiong; Wang, Shi-Yao; Zhou, Man; Zhou, Wang; Yang, Ai-Xiang; Yan, Peng-Xun; Chen, Xi-Meng

    2015-06-01

    We extend our previous work of a classical over-barrier ionization (COBI) model to calculate the single ionization cross sections of noble gases ranging from He to Xe at strong perturbative energies. The calculation results are in good agreement with extensive experimental data. The scaling law of single ion–atom impact ionization cross sections of noble gases on projectile charge q and energy E, also on target ionization energy I is drawn from the model. Project supported by the National Natural Science Foundation of China (Grants Nos. 11174116, and 11175075).

  17. 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

  18. Simulating mesoscale transport and diffusion of radioactive noble gases using the Lagrangian particle dispersion model

    Microsoft Academic Search

    Cheol-Hee Kim; Chang-Keun Song; Sang-Hyun Lee; Sang-Keun Song

    2008-01-01

    In order to simulate the impact of mesoscale wind fields and to assess potential capability of atmospheric Lagrangian particle dispersion model (LPDM) as an emergency response model for the decision supports, two different simulations of LPDM with the mesoscale prognostic model MM5 (Mesoscale Model ver. 5) were driven. The first simulation of radioactive noble gas (85Kr exponent) emitted during JCO

  19. Spectral analysis of ionized noble gases and implications for astronomy and laser studies

    Microsoft Academic Search

    J. Reyna Almandos; F. Bredice; M. Raineri; M. Gallardo

    2009-01-01

    Studies of emission spectra of noble gas ions have been carried out in La Plata for more than 35 years, several of them in collaboration with other groups. Knowledge of the wavelengths, intensities and shapes of the lines of different species of neon, argon, krypton and xenon in intermediate and high degrees of ionization is important not only to study

  20. Ultrahigh Sensitivity Heavy Noble Gas Detectors for Long-Term Monitoring and for Monitoring Air

    SciTech Connect

    John D. Valentine

    2005-07-28

    The primary objective of this research project is to develop heavy noble gas (krypton, xenon, and radon) detectors for (1) long-term monitoring of transuranic waste, spent fuel, and other uranium and thorium bearing wastes and (2) alpha particle air monitors that discriminate between radon emissions and other alpha emitters. DOE needs that are addressed by this project include improved long-term monitoring capability and improved air monitoring capability during remedial activities. Successful development and implementation of the proposed detection systems could significantly improve current capabilities with relatively simple and inexpensive equipment.

  1. An experimental high pressure line shape study of the rubidium D1 and D2 transitions with the noble gases, methane, and ethane

    NASA Astrophysics Data System (ADS)

    Pitz, Greg A.; Hager, Gordon D.; Tafoya, Tiffany B.; Young, Joseph W.; Perram, Glen P.; Hostutler, David A.

    2014-02-01

    At high pressure the rst resonance lines of rubidium have been observed to broaden asymmetrically. A the- oretical line shape for this asymmetry has been determined via the Anderson-Talman theory and the impact approximation. The broadening and shift rates compared nicely to previous low pressure results and the rates for asymmetry have been measured for the noble gases, methane, and ethane.

  2. 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.

  3. Colloidally separated samples from Allende residues - Noble gases, carbon and an ESCA-study

    NASA Technical Reports Server (NTRS)

    Ott, U.; Kronenbitter, J.; Flores, J.; Chang, S.

    1984-01-01

    Results are presented which strengthen the hypothesis of heterogeneity among the carbon- and nitrogen-bearing phases of the Allende meteorite. These data also highlight the possibility of performing physical separations yielding samples in which some of the noble gas- and carbon-bearing phases are extraordinarily predominant over others. The conclusion, based on mass and isotope balance arguments, that a significant portion of the carbonaceous matter in Allende is likely to be gas-poor or gas-free need not weaken the case for carbonaceous carriers for the major noble gas components. The concept that acid-soluble carbonaceous phases contain a multiplicity of components, each of which may have formed under a multiplicity of different physical-chemical conditions, is reemphasized by the results of the present study.

  4. 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.

  5. 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).

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

    NASA Astrophysics Data System (ADS)

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

    1985-04-01

    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.

  7. A Single Lodranite/Acapulcoite Parent Body: Noble Gases in Lodranite QUE 93148 and Acapulcoite ALH 81261

    NASA Astrophysics Data System (ADS)

    Weigel, A.; Eugster, O.; Marti, K.; Michel, R.

    1995-09-01

    We continue our comprehensive studies of the cosmic ray exposure history of lodranites [1] to include new noble gas measurements in the QUE 93148 lodranite and the ALH 81261 acapulcoite. In addition, we model the production rates of cosmogenic nuclides in lodranites and acapulcoites using the HERMES high energy transport code [2], in order to test whether conventional production rates can be extrapolated to this group of small meteoroids which reveal very large values of the shielding parameter 22Ne/21Ne (Table 1). The model calculations are based on the same excitation functions of p- and n-induced reactions as used in recent calculations [3,4]. We extended our studies to acapulcoites, since petrologic, mineralogic, and O-isotopic investigations [5] as well as chemical investigations [6] suggest that lodranites and acapulcoites are residues of varying degree of partial melting, consistent with an origin on a common parent body. Whether a collisional event on the common parent body ejected both types of meteorites can be investigated by an analysis of the transfer times to Earth, specifically their cosmic-ray exposure ages. Because the contents of trapped He, Ne, and Ar in lodranites and acapulcoites are very low we can derive reliable cosmogenic noble gas contents. Using the composition-adjusted production rates for cosmogenic noble gases in achondrites [7], and adopting the shielding-parameter dependence for H-chondrites the exposure ages of [1] are obtained. For lodranites these exposure ages overlap those calculated [8] from 26Al and 10Be measurements. For the acapulcoites our exposure ages agree with those [5] calculated with the Graf-model [9], as well as with the shielding-independent exposure age for Acapulco that is based on the 36Cl-36Ar method[10]. The large spread in the exposure ages can be attributed to the highly variable target element abundances, as multiple measurements on several aliquots show unusually large variations. The fact that the average exposure age T3 is 44% higher than the average T21 in the case of lodranites, and 13% higher for acapulcoites, cannot be explained by the variable chemical composition. Studies of Lodran mineral separates [1] suggest that the Lodran parent meteoroid was enriched in metal (up to 65%). This means that the Ne production rates for bulk samples are overestimated. The average cosmogenic noble gas contents, average shielding, and main target element abundances of lodranites and acapulcoites (Table 1) coincide fairly well. The slightly higher Mg abundance in lodranites translates into a higher Ne production rate and therefore a lower exposure age T21. The higher Ca abundance in acapulcoites leads to a higher Ar production rate and, therefore, a lower T38. The production of cosmogenic 3He, however, is quite insensitive to variations in chemical composition and shielding. We observe good agreement between the T3 values of lodranites (6.2+/-0.5Ma) and acapulcoites (6.8+/-1.1Ma) and conclude that a single collisional event can account for the currently known exposure ages of lodranites and acapulcoites. Acknowledgments: We thank NASA and the MWG for the meteorite samples. This work was supported by the Swiss NSF and partially by the Deutsche Forschungsgemeinschaft. References: [1] Weigel A. et al. (1994) Meteoritics, 29, 548. [2] Cloth P. et al. (1988) JUEL-2203. [3] Michel R. et al. (1995) Planet. Space Sci., in press. [4] Herpers U. et al. (1995) Planet. Space Sci., in press. [5] McCoy T. J. et al. (1995) GCA, submitted. [6] Zipfel J. and Palme H. (1993) LPS XXIV, 1579. [7] Eugster O. and Michel Th. (1995) GCA, 59, 177. [8] Xue et al. (1994) LPS XXV, 1523. [9] Graf Th. et al. (1990) GCA, 54, 2521. [10] Graf Th. et al., this volume. Table 1 shows average cosmogenic noble gas contents, main target element abundances, and exposure ages of eight lodranites and four acapulcoites.

  8. Clathrate formation and the fate of noble and biologically useful gases in Lake Vostok, Antarctica

    E-print Network

    Priscu, John C.

    if the carbon input is 1% of the air input and the lake water is fresh water. The redox state of the lake is set by the high oxygen concentration which is 50 times more than air-equilibrated water and may be a severe composition for air (3.71). [4] Originally it was suggested that the gases in Lake Vostok would build up

  9. Isotopic anomalies of noble gases in meteorites and their origins. III - LL-chondrites

    NASA Technical Reports Server (NTRS)

    Alaerts, L.; Lewis, R. S.; Anders, E.

    1979-01-01

    Nine LL-chondrites were studied by selective etching to characterize the noble gas components in three mineral fractions: HF-HCl-solubles, chromite and carbon. The Ne-20/Ar-36 ratio is considered, noting that chondrites of different petrologic types cannot all be derived from the same volatile rich ancestor, but must have formed over a range of temperatures, with correspondingly different volatile contents. Variations in the carbonaceous chondrite fission (CCFXe) component in LL3, LL5, and LL6 chondrites are discussed, noting that if CCFXe comes from a supernova, then its distribution in LL-chondrites requires three presolar carrier minerals of the right solubility properties, containing three different xenon components. However, if CCFXe comes from fission of a volatile superheavy element, then its decrease from LL3 to LL6 can be attributed to less complete condensation from the solar nebula. Finally, the three types of primordial xenon components which occur in different minerals of the same meteorite are described.

  10. Noble gases and halogens in Graves Nunataks 06129: The complex thermal history of a felsic asteroid crust

    NASA Astrophysics Data System (ADS)

    Claydon, Jennifer L.; Crowther, Sarah A.; Fernandes, Vera A.; Gilmour, Jamie D.

    2015-06-01

    The meteorite Graves Nunataks 06128/06129 is a rare example of felsic asteroidal crust. Knowledge of its history can help shed light on the evolution processes of planetesimals. The noble gases can be used to constrain both the chronology of meteorites and the processes that result in movements of volatile elements on asteroidal bodies. We have examined the I-Xe and Ar-Ar systems of the plagioclase-rich achondrite, Graves Nunataks 06129 by high-resolution laser step-heating of irradiated samples. Iodine and 129Xe? are both present but are released at different temperatures and do not show a correlation, therefore the I-Xe system in GRA 06129 has no chronological significance. We propose that radiogenic 129Xe? was lost from primary phases and parentless 129Xe? was later introduced into the rock by interaction with a fluid sourced from a reservoir that evolved with a high I/Xe ratio. This could have been the same halogen-rich fluid that induced the conversion of merrillite and pyroxene into chlorapatite. Inherited 40Ar (i.e. not generated by in situ decay of 40K) is also present in one of three fragments studied here and may have been introduced at the same time as parentless 129Xe?.

  11. Noble Gases in Alpine Gold: U/Th-He Dating and Excesses of Radiogenic He and AR

    NASA Astrophysics Data System (ADS)

    Eugster, O.; Hofmann, B.; Krahenbuhl, U.; Neuenschwander, J.

    1992-07-01

    Gold precipitates in hydrothermal fluids along with other heavy elements, such as Ag and Pt. In order to explore the possibility of dating the formation of gold we determined the concentrations of U, Th, and their decay product ^4He, as well as the K and ^40Ar concentrations in vein-type gold and in placer gold samples. The gold-quartz veins at Brusson in the south-western alps were formed approximately 32 Ma ago during an episode of tectonic uplift (Diamond, 1990). Alpine material was deposited as sediment layers in the region of central Switzerland and placer gold is thus relatively abundant in the rivers of the Napf area. We washed placer gold from the river Grosse Fontanne in 1990 and 1991. Placer gold that had been collected from the river Kruempelgraben in 1933 and a sample of vein-type free gold grown on quartz rock from the Brusson area (Val d'Ayas) have been obtained from the Museum of Natural History in Bern. Table 1 gives the results. Most of the ^4He is released above 1050 degrees C, that is when gold melts, indicating that gold is extremely well retentive for He. From the ^4He concentration of (269 +- 20) x 10^-8 cm^3 STP/g, (0.4 +- 0.1) ppm U, and (0.9 +- 0.3) ppm Th for vein-type gold we calculate a U/Th-He age of (36 +- 8)Ma. This age agrees within errors with the proposed age of 32 Ma. The data given in Table 1 show that all placer gold samples contain excesses of radiogenic ^4He and ^40Ar relative to the concentrations expected from the U/Th and K decay, respectively, if we assume a formation age of 32 Ma. The quartz sample is depleted in ^4He but strongly enriched in radiogenic ^40Ar. The excess of ^40Ar(sub)rad is easier to explain than that of ^4He. Vein-type gold and placer gold contain quartz inclusions (Schmid, 1973). The high ^40Ar(sub)rad content of quartz (Table 1) indicates that the ^40Ar(sub)rad excess of gold originates from quartz inclusions. Excess ^4He in gold must be of radiogenic origin. Taking ^20Ne and ^36Ar as a measure for the quantity of trapped atmospheric noble gases we estimate atmospheric ^4He in the gold samples to be three to five orders of magnitude below the observed ^4He concentration. Placer gold is finely distributed in rock material and might be exposed to an alpha-particle irradiation from neighboring U/Th-rich minerals. An alternative He source are inclusions of U/Th-rich minerals, such as zircon, either within the gold material or mechanically worked into the spangles as they were part of the river detritus. Acknowledgement: We thank the Swiss NSF for their support. References: Diamond L.W. (1990) Am. J. of Science 290, 912-958. Schmid K. (1973) Schw. Min. Petr. Mitt. 53, 125-156. Table 1, which in the hard copy appears here, shows concentrations of He, Ne, and Ar (10^-8 cm^3 STP/g) and of K, Th, and U (ppm) in vein-type free gold, placer gold, and quartz. The ^3He and ^21Ne signals were below detection limits, that is ^4He/^3He in gold is >100'000. Average ^20Ne/^22Ne ratios in gold and quartz are 10.2 +- 0.2, that is about 4% larger than in the terrestrial atmosphere. Average ^36Ar/^38Ar = 5.2 +- 0.2 (within errors identical to ^36Ar/^38Ar in air). 1) Sample sizes 50-100 mg. 2) Radiogenic ^40Ar = ^40Ar-295.5 x ^36Ar. 3) Calculated from U/Th and ^40K decay.

  12. Determination of optical properties by third-harmonic generation in noble gases in unfocused laser beams

    SciTech Connect

    Ferrell, W.R.

    1985-03-01

    A new laser technique involving phase-matched third-harmonic generation in unfocused laser beams has been used to determine vacuum ultraviolet (VUV) oscillator strengths in xenon, VUV indices of refraction for the buffer gas (krypton or argon), and the VUV absorption coefficients were determined through total ionization measurements in the frequency regions of phase matching resulting from the interaction of unfocused linearly polarized light with mixtures of xenon and positively dispersive buffer gases. Since the multiphoton ionization mechanism is sharply dominated by the dimer absorption of third-harmonic photons, the ionization signal provides an excellent probe for determination of these optical parameters. Absolute ionization measurements were made through use of a proportional counter which was calibrated by the ionization resulting from an internal /sup 55/Fe source. 38 refs., 33 figs., 3 tabs.

  13. Tracing the Galapagos Volcanic Groundwater System Using Noble Gases and Stable Isotopes

    NASA Astrophysics Data System (ADS)

    Warrier, R. B.; Castro, M. C.; Hall, C. M.; D'Ozouville, N.

    2010-12-01

    Water samples were collected from springs and groundwater in the Galapagos Islands of San Cristobal and Santa Cruz and analyzed for He, Ne, Ar, Kr, and Xe concentrations and stable isotopes. One lake sample was also collected in San Cristobal and analyzed for the same elements. Noble gas temperatures (NGTs) were calculated for all samples for different assumed altitudes, and subsequently compared with possible temperature values within both islands. Many San Cristobal and Santa Cruz samples indicate recharge occurring at temperatures and altitudes which are consistent with those in place in the islands. Specifically, recharge altitudes between 229 and 730m and temperatures of 19.95 (±1.13) and 25.92 (±2.0)°C are found for San Cristobal, while recharge altitudes between 160 and 870m and temperatures between 20.05 (±2.07) and 27.12 (±0.47)°C are found for Santa Cruz, suggesting that these are the altitude and temperature range values at which recharge occurs in these two islands, respectively. Most samples which fall within expected altitude and temperature ranges are located at low altitudes (<~420m a.s.l) while all others are located at higher altitudes. Comparison of calculated NGTs of these low altitude samples to the average hot season (Jan-May) temperature along with the observed temperature gradient suggests that recharge occurs mostly during the hot season at low altitudes. Results also suggest that recharge likely occurs during both the hot and the Garua (June-December) seasons at high altitudes. ?D and ?18O were compared with volume-weighted mean monthly values for rainfall. All our samples fall within both stable isotope end-members, April and September. In particular, a set of samples lie close to the more depleted rainwater samples resulting from intense precipitation events during the hot season (Jan-May) and form the same subset of low altitude samples identified using NGTs. The stable isotopic composition of these water samples also suggest that recharge occurs mostly during the hot season at these low altitude locations. By contrast, the isotopic signature of high altitude samples lies between the subset of enriched Garua rainfall samples and that of the depleted hot season rainfall samples, strongly pointing to recharge during both seasons as previously suggested by NGTs. Our combined NGT and stable isotope analyses thus leads to a common conclusion, i.e., samples predominantly recharged during the hot season are found at lower altitudes, while samples pointing to recharge during both seasons appear to be located at higher altitudes. A number of samples point to altitudes that are far higher than the summit of these islands, with most of these samples displaying temperatures that are also too low to be consistent with the temperature range in place on both islands. Such a trend suggests that the available time for rainwater in these samples to re-equilibrate with the soil air of the islands might be insufficient due to rapid water infiltration where soils are very thin or absent, and fractured bedrock has high permeability.

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

    NASA Astrophysics Data System (ADS)

    Ottonello, Giulio; Richet, Pascal

    2014-01-01

    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 (??) 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 ?s, along the guidelines already used in the past for simple media such as water or benzene. The ?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.

  15. Heavy Noble Gas Systematics of the Rochambeau Rift Plume: Towards Understanding the Xenon record of early Earth heterogeneities Maria Kocsisn Pet 1, Sujoy Mukhopadhyay 1, Katherine A. Kelley 2

    E-print Network

    Mukhopadhyay, Sujoy

    Heavy Noble Gas Systematics of the Rochambeau Rift Plume: Towards Understanding the Xenon record in isotopic composition and relative noble gas abundances between the MORB source and OIB sources do exist and have been recently characterized to high precision [1]. Here, we present new noble gas data (Ne, Ar, Xe

  16. Genesis Noble Gas Measurements

    NASA Technical Reports Server (NTRS)

    Hohenberg, Charles M.

    2005-01-01

    The original thrust of our Genesis funding was to extend and refine the noble gas analytical capabilities of this laboratory to improve the precision and accuracy of noble gas measurements in order to optimize the scientific return from the Genesis Mission. This process involved both instrumental improvement (supplemented by a SRLIDAP instrument grant) and refinement of technique. The Genesis landing mishap shifted our emphasis to the irregular aluminum heat shield material from the flat collector wafers. This has required redesign of our laser extraction cells to accommodate the longer focal lengths required for laser extraction from non-flat surfaces. Extraction of noble gases from solid aluminum surfaces, rather than thin coatings on transparent substrates has required refinement of controlled-depth laser ablation techniques. Both of these bring new problems, both with potentially higher blanks form larger laser cells and the larger quantities of evaporated aluminum which can coat the sapphire entrance ports. This is mainly a problem for the heavy noble gases where larger extraction areas are required, necessitating the new aluminum vapor containment techniques described below. With the Genesis Mission came three new multiple multiplier noble gas mass spectrometers to this laboratory, one built solely by us (Supergnome-M), one built in collaboration with Nu-Instruments (Noblesse), and one built in collaboration with GVI (Helix). All of these have multiple multiplier detection sections with the Nu-Instruments using a pair of electrostatic quad lenses for isotope spacing and the other two using mechanically adjustable positions for the electron multipliers. The Supergnome-M and Noblesse are installed and running. The GVI instrument was delivered a year late (in March 2005) and is yet to be installed by GVI. As with all new instruments there were some initial development issues, some of which are still outstanding. The most serious of these are performance issues with the miniature channel electron multipliers. The delayed installation of Helix by the GVI is partly due to failure of the initial batch of Burle channel multipliers to perform as expected. A number of the channel multipliers designed for Noblesse by Burle have also failed upon baking. Burle has now refined the design of these and we have installed two of the new multipliers and are assessing their performance. The remaining multipliers Will be upgraded to the new design from Burle once we confirm that the problem has been fixed.

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. Using carbon and water isotopes and noble gases to assess the origin of methane in fresh water aquifers in the south of the Netherlands

    NASA Astrophysics Data System (ADS)

    Broers, Hans Peter; de Weert, Jasperien; Vonhof, Hubert; Janssen, Renee; Sueltenfuss, Juergen; Aeschbach-Hertig, Werner; Castelijns, Jeroen

    2015-04-01

    Groundwater in the Dutch subsurface is known to contain substantial concentrations of methane of which the origin is not always clear. The Dutch subsurface contains relatively high organic matter contents which makes a biogenic origin plausible, however few studies have used water and carbon isotopes to deduce the origin of methane. In relation to possible future exploitation of deep shale gas resources, it is now considered important to assess base line quality of fresh groundwater in overlying aquifers from which drinking water is produced. Therefore, we sampled the raw water of 41 large public supply well fields in the south of the Netherlands which represents a mixture of groundwater of different ages and used the a discrete travel time distribution model (DTTDM, Visser et al. 2013, WRR) in order to quantify the age distribution of the mixture. Measurements included major ion chemistry, 3H, 3He, 4He, 18O, 2H, 14C, 13C-DIC and 13C-CH4 and the full range of noble gases. 13C-CH4 measurements were carried out using a Picarro G2201-i CRDS analyser. The heavier noble gases enable the calculation of the Noble Gas Temperature (NGT) which characterizes the temperature of past recharge conditions. The 14C apparent age of each mixture was derived correcting for dead carbon sources and included carbonate dissolution and methanogenesis as the defining processes. The 13C-CH4 measurements showed a range of ?-values between -70 and -100‰, which give a clear indication for biogenic methane. No clear relations between 13C-CH4 and 13C-DIC or the 4He/CH4 ratio were observed. However, clear spatial patterns indicated that more depleted values are grouped in specific areas. The 13?CH4 values did not show a clear relation with the age distribution of the pumped water, even though a large range of age distributions was observed including old water with an age of > 25 k yrs. We believe that spatial differences in organic matter contents, origin of the geological deposits and/or the methanogenesis process itself determine the methane isotope ratios in this part of the Netherlands.

  4. Dissolved noble gases and stable isotopes as tracers of groundwater dynamics in the Lower Rhine Embayment, Germany

    NASA Astrophysics Data System (ADS)

    Gumm, L. P.; Dennis, P. F.; Bense, V. F.; Hiscock, K. M.; Cremer, N.

    2009-04-01

    A multiple environmental tracer approach has been applied to achieve an improved understanding of groundwater dynamics in the Lower Rhine Embayment, Germany. The main emphasis has been to utilise dissolved noble gas and noble gas determined excess air concentrations in addition to the stable isotopes of hydrogen, oxygen, carbon and strontium. It is hypothesised that a relationship between noble gas excess air concentrations and the magnitude and frequency of water table fluctuations, both natural and as a result of large scale water abstraction can be quantified and used as an indicator of groundwater recharge, flow rate and residence times. The research has also provided further insight into the role of fault zones on local and regional groundwater dynamics. The hydrogeology of the Lower Rhine Embayment is complex and dynamic, and consists of unconsolidated sedimentary deposits with a number of laterally continuous lignite seams. Large scale open pit mining has a significant impact on the regional groundwater system primarily due to water abstraction and subsequent lowering of the water table. The layered aquifer system is intersected by numerous NW-SE striking fault zones that have been shown to have the potential to act as both barriers to groundwater flow and as preferential flow paths. Groundwater samples taken from observation boreholes in close proximity to fault zones have provided preliminary results that indicate hydrogen and oxygen isotope anomalies and extremely high helium-4 concentrations in the shallow aquifer layers. Groundwater exchange between the lower and upper aquifer systems is impeded by confining clay layers and a continuous lignite seam of very low permeability. This suggests that palaeowater from depth is mixing with modern water of meteoric origin in the upper aquifer as a result of conduit flow from depth towards the upper aquifer layer within the fault zone.

  5. Influence of diffusion and nonequilibrium populations on noble-gas plasmas in electric arcs

    Microsoft Academic Search

    J. F. Uhlenbusch; E. Fischer

    1971-01-01

    Measurements and calculations of temperatures, densities, and field-strength-current characteristics of cascade arcs burning in noble gases under atmospheric pressure are reported. The evaluation of measured arc data assuming Saha equilibrium [complete local thermal equilibrium (LTE)] is not in agreement with the detailed solution of the balance equations. The temperatures of electrons and heavy particles and the density of electrons and

  6. Study of heavy gas effects on the atmospheric dispersion of dense gases. Revision 1

    SciTech Connect

    Ermak, D.L.; Chan, S.T.

    1985-04-01

    In this paper, four different types of dispersion simulations are compared with the results from three heavy gas dispersion experiments. The experiments include two different release gases (LNG vapor, a cold dense gas and NO/sub 2/, an isothermal dense gas) and three different wind speeds and atmospheric stabilities. The four types of dispersion simulations are a heavy gas simulations, a neutrally buoyant gas simulation, and two types of trace gas simulations. We use two models (FEM3 and Steady-State SLAB) to make the predictions. FEM3 simulates the dispersion of a heavy gas by solving the time-dependent, three-dimensional conservation equations and uses similarity profiles to determine the crosswind dependence. The purpose of this paper is to demonstrate how the inclusion of heavy gas phenomena and the choice in concentration averaging time affect the concentration prediction from a heavy gas release. 13 refs., 9 figs., 1 tab.

  7. Origin and Processes Highlighted By Noble Gases Geochemistry of Submarine Gas Emissions from Seeps at the Aquitaine Shelf (Bay of Biscay):

    NASA Astrophysics Data System (ADS)

    Battani, A.; Ruffine, L.; Donval, J. P.; Bignon, L.; Pujol, M.; Levaché, D.

    2014-12-01

    Noble gases are widely used as tracers to both determine fluid origin and identify transfer processes governing fluid flow in natural systems. This work presents the preliminary results and interpretations from submarine gas samples collected during the GAZCOGNE2 cruise (2013). The seepage activity and the spatial distribution of the widespread emission sites encountered at this area are described by (Dupré et al. 2014). Gas composition shows that methane is the dominant species compared to the C2+. The associated ?13C and ?D signatures point to a biogenic origin- through CO2 reduction- of the gas. Helium concentrations are very low, ranging from 0.1 and 2.3 ppm, indicating a low residence time of the fluids in the subsurface. However, the resulting helium isotopic ratios are mostly crustal fingerprinted (around 0.02). The R/Ra values sometimes exhibit higher value of 0.2, indicative either an ASW (air saturated water) value, or the fingerprint of ancient mantle helium, the later in agreement with the geological structural context of the Parentis Basin. Most of the samples exhibit a mixing between ASW and air, probably by excess air addition to the initial ASW concentration. The elemental Ne/Ar ratio is remarkably constant for the totality of the samples, with a value typical of ASW (0.2). This result implies that the migrating gas phase is "stripping" the original water matrix from its noble gas content, as described by Gillfillian et al., 2008. This further indicates that an intermediate reservoir of biogenic gas should be present at depth. The GAZCOGNE study is co-funded by TOTAL and IFREMER as part of the PAMELA (Passive Margin Exploration Laboratories) scientific project. References: Dupré, S., L. Berger, N. Le Bouffant, C. Scalabrin, and J. F. Bourillet (2014), Fluid emissions at the Aquitaine Shelf (Bay of Biscay, France): a biogenic origin or the expression of hydrocarbon leakage?, Continental Shelf Research, doi:10.1016/j.csr.2014.07.004. Gilfillan S. M.V., Ballentine C. J. Holland G. a, Blagburn D.Sherwood Lollar B., Stevens S., Schoell, M., Cassidy, M. (2008) The noble gas geochemistry of natural CO2 gas reservoirs from the Colorado Plateau and Rocky Mountain provinces, USA

  8. Heterogeneities from the first 100 million years recorded in deep mantle noble1 gases from the Northern Lau Back-arc Basin2

    E-print Network

    Mukhopadhyay, Sujoy

    characterization of the mantle source compositions. Here we present new high-precision noble15 gas data from gas)34 heterogeneities in the Earth's deep mantle. Consequently, the primitive noble gas reservoir35 Introduction42 The noble gas compositions of mantle-derived basalts provide information on the43 degassing

  9. Heterogeneities from the first 100 million years recorded in deep mantle noble gases from the Northern Lau Back-arc Basin

    E-print Network

    Mukhopadhyay, Sujoy

    of the mantle source compositions. Here we present new high-precision noble gas data from gas-rich basalts from the Iceland plume, our noble gas observations require the formation and preservation of less material. & 2013 Elsevier B.V. All rights reserved. 1. Introduction The noble gas compositions of mantle

  10. Population dose estimation from a hypothetical release of 2. 4 x 10⁶ curies of noble gases and 1 x 10⁴ curies of ¹³¹I at the Three Mile Island Nuclear Station, Unit 2

    Microsoft Academic Search

    C. D. Berger; S. J. Cotter; C. W. Miller; S. R. Glandon

    1981-01-01

    Beginning on March 28, 1979, a sequence of events occurred at the Three Mile Island Nuclear Station Unit 2 (TMINS-2) nuclear power reactor which resulted in the accidental release of approximately 2.4 x 10⁶ Ci of noble gases and 13 to 15 Ci ¹³¹I. A comprehensive study of this incident has been reported by the President's Commission on the Accident

  11. 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.

  12. Isotopic composition of noble gases in geothermal fluids of the Krušné Hory Mts., Czechoslovakia, and the nature of the local geothermal anomaly

    NASA Astrophysics Data System (ADS)

    Polyak, B. G.; Prasolov, E. M.; ?ermák, V.; Verkhovskiy, A. B.

    1985-03-01

    The contents and isotopic composition of all noble gases in the fluids from two localities (Karlovy Vary and Franti\\vskovy Lázn?) in Western Czechoslovakia are given. The data show: (1) atmospheric Ne, Ar, Kr and Xe, which indicates meteoric recharge; (2) excess He, attributed to radiogenic contributions; (3) a small excess of Ne, but the data shed no light on its origin. Even though there is no evidence of any juvenile component in these mineral waters, part of the dissolved He is believed to be of deep (mantle) origin. Correlation between the ratio 3He /4He and heat flow has been reported in the literature: our data enabled a direct test of this relationship and proved its fairly good validity. The combined interpretation of the heat flow and isotopic composition shows that the local heat flow anomaly in the Krušné Hory graben is of deep origin and was produced by the mass outflow which occurred during the Alpine activation of the Bohemian Massif.

  13. 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.

  14. Noble gas isotopes and the chemical composition of geothermal gases from the eastern part of the Büyük Menderes Graben (Turkey)

    NASA Astrophysics Data System (ADS)

    Wiersberg, T.; Süer, S.; Güleç, N.; Erzinger, J.; Parlaktuna, M.

    2011-12-01

    We present noble gas isotope and gas composition data from eight production wells of the Kizildere geothermal field and from six gas discharging pools from the adjacent Tekke Hamam geothermal field, situated in the eastern segment of the Büyük Menderes Graben system in western Anatolia (Turkey). Gas from both locations is composed mainly of CO 2 with minor contributions of N 2, H 2S, CH 4, O 2, Ar, H 2, C 2+ and He, with higher contents of H 2S, He and C 2+ in Tekke Hamam samples. Air corrected helium isotope ratios reveal a mantle origin for samples from both locations, but 3He/ 4He ratios are lower and more variable at Kizildere (0.96-2.06 R a) than at Tekke Hamam (2.36-2.91 R a, R a is the atmospheric 3He/ 4He ratio of 1.39 × 10 - 6 ). Kizildere gas contains less 4He (0.7-2.2 ppmv) and 3He (~ 2-5 × 10 - 6 ppmv) than gas from Tekke Hamam (2.5-3.5 ppmv and ~ 1 × 10 - 5 ppmv, respectively). CO 2/ 3He ratios of 2-8 × 10 11 at Kizildere and 0.7-1 × 10 11 at Tekke Hamam are higher than average mantle values (~ 2 × 10 9). Within the Kizildere geothermal field, reservoir temperatures and CO 2/ 3He and CH 4/C 2H 6 ratios increase and 3He/ 4He ratios decrease from southwest to northeast. Interpolation of a linear trajectory between 3He/ 4He and temperature from Kizildere delivers temperature of 173 °C-184 °C for the source reservoir of Tekke Hamam, in good agreement with measured reservoir temperatures from well TH-2 at Tekke Hamam (171 °C). The low helium content, the variable helium isotope composition and the higher CO 2/ 3He ratios at Kizildere can be explained by temperature-dependent partial removal of mantle-derived helium, e.g. through vapor separation, followed by addition of radiogenic helium. Kizildere samples derive from the remaining water phase after gas separation, while Tekke Hamam samples may represent the gas phase liberated by the former process. The pristine 3He/ 4He ratio of helium at Kizildere can be calculated as 2.2 R a, close to helium isotope ratios observed at Tekke Hamam. Partial removal of helium may also account for the higher and T-dependent CO 2/ 3He ratios at Kizildere, compared to Tekke Hamam, but such process alone cannot explain the overall high CO 2/ 3He ratios (> 7 × 10 10) and calls for contribution of CO 2 from interaction between geothermal fluids and carbonate reservoir rock. Noble gas abundances indicate mixing with cold meteoric water in the reservoir.

  15. LaRC results on nuclear pumped noble gas lasers

    Microsoft Academic Search

    R. J. Deyoung

    1979-01-01

    The recent experiment and theoretical results obtained for noble gas nuclear laser systems are presented. It is shown that the noble gas lasers are among the easiest systems to pump by nuclear excitation and as a result, all of the noble gases except He have lased under nuclear excitation. The noble gas systems are not ideal for high-power applications but

  16. Catching the role of anisotropic electronic distribution and charge transfer in halogen bonded complexes of noble gases

    NASA Astrophysics Data System (ADS)

    Bartocci, Alessio; Belpassi, Leonardo; Cappelletti, David; Falcinelli, Stefano; Grandinetti, Felice; Tarantelli, Francesco; Pirani, Fernando

    2015-05-01

    The systems studied in this work are gas-phase weakly bound adducts of the noble-gas (Ng) atoms with CCl4 and CF4. Their investigation was motivated by the widespread current interest for the intermolecular halogen bonding (XB), a structural motif recognized to play a role in fields ranging from elementary processes to biochemistry. The simulation of the static and dynamic behaviors of complex systems featuring XB requires the formulation of reliable and accurate model potentials, whose development relies on the detailed characterization of strength and nature of the interactions occurring in simple exemplary halogenated systems. We thus selected the prototypical Ng-CCl4 and Ng-CF4 and performed high-resolution molecular beam scattering experiments to measure the absolute scale of their intermolecular potentials, with high sensitivity. In general, we expected to probe typical van der Waals interactions, consisting of a combination of size (exchange) repulsion with dispersion/induction attraction. For the He/Ne-CF4, the analysis of the glory quantum interference pattern, observable in the velocity dependence of the integral cross section, confirmed indeed this expectation. On the other hand, for the He/Ne/Ar-CCl4, the scattering data unravelled much deeper potential wells, particularly for certain configurations of the interacting partners. The experimental data can be properly reproduced only including a shifting of the repulsive wall at shorter distances, accompanied by an increased role of the dispersion attraction, and an additional short-range stabilization component. To put these findings on a firmer ground, we performed, for selected geometries of the interacting complexes, accurate theoretical calculations aimed to evaluate the intermolecular interaction and the effects of the complex formation on the electron charge density of the constituting moieties. It was thus ascertained that the adjustments of the potential suggested by the analysis of the experiments actually reflect two chemically meaningful contributions, namely, a stabilizing interaction arising from the anisotropy of the charge distribution around the Cl atom in CCl4 and a stereospecific electron transfer that occurs at the intermolecular distances mainly probed by the experiments. Our model calculations suggest that the largest effect is for the vertex geometry of CCl4 while other geometries appear to play a minor to negligible role.

  17. Influence of noble metals (Rh, Pd, Pt) on Co-saponite catalysts for HDS and HC of heavy oil

    Microsoft Academic Search

    Mohammad M. Hossain

    2006-01-01

    The promotional effects of trace amount of noble metal (Rh, Pd, Pt) on Co-saponite (high surface area) catalysts were studied by different characterization and evaluation techniques. BET experiments showed that the specific surface area and the pore volume of the noble metal promoted catalysts remained almost unchanged. The reduction\\/adsorption characteristics of the catalysts were significantly influenced by the presence of

  18. Adsorption and desorption of noble gases on activated charcoal: I. sup 133 Xe 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

    Detailed desorption studies using petroleum-based activated charcoals were conducted in monolayers and packed beds. Less extensive studies were conducted on several other types of charcoal. Kinetic studies, using {sup 133}Xe, demonstrated the existence of a micropore volume with entrance capillaries that together determined the response characteristics of charcoal to external concentration gradients of tracer gases. This new two-phase model, composed of micropores and entrance capillaries, describes the desorption dynamics of an adsorbed gas in the presence of water vapor. Condensed water vapor in the entrance capillaries of the charcoal reduced the effective pore radius and increased the diffusion half-time. Water could also adversely affect the integrating capability of the charcoal dramatically if the adsorbed water completely blocked the entrance capillaries. The amount of adsorbed water required to block the capillaries varied with the charcoal type and was termed here as the break-point. The desorption parameters measured in this work can be used to design an improved passive Rn monitor to effectively integrate during a 3-7 d exposure period by eliminating the adverse effects of water vapor. The improved canister design would provide more accurate and reproducible measurements of indoor Rn concentrations than are currently available.

  19. Multiple Ion Counting in Noble Gas Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Ott, U.; Baecker, B.; Trieloff, M.

    2014-11-01

    We describe the setup and operation of our Noblesse noble gas mass spectrometer with multiple ion counting detector. As a first project we have analyzed all noble gases (He though Xe) in micrometeorites collected in Antarctica.

  20. Noble Gases Trapped In Diamond Nanograins In Interstellar Media and In The Laboratory Or How To Produce A Lot of Nanodiamonds Almost Indistinguishable From Meteoritic Ones

    Microsoft Academic Search

    A. P. Koscheev; S. P. Kabanov; U. Ott

    2002-01-01

    Presolar diamond nanograins found in meteorites carry noble gas atoms thought to be produced by stellar nucleosynthesis. To extract information on the nuclear reac- tions from the laboratory study of meteoritic diamonds (e. g. by pyrolysis noble gas mass spectrometry) it is necessary to know the mechanisms of both gas entrapment near stars and gas release in the laboratory. Along

  1. Noble gas anomalies related to high-intensity methane gas seeps in the Black Sea

    NASA Astrophysics Data System (ADS)

    Holzner, C. P.; McGinnis, D. F.; Schubert, C. J.; Kipfer, R.; Imboden, D. M.

    2008-01-01

    Dissolved noble gases and tritium were analyzed at a series of high-intensity methane gas seeps in the Black Sea to study the transport and gas exchange induced by bubble-streams in the water column. These processes affect marine methane emissions to the atmosphere and are therefore relevant to climate warming. The seep areas investigated are located in the Dnepr paleo-delta, west of Crimea, and in the Sorokin Trough mud volcano area, south-east of Crimea. Noble gas concentration profiles at active seep sites revealed prominent anomalies compared to reference profiles that are unaffected by outgassing. Supersaturations of the light noble gases helium and neon observed relatively close to the sea floor are interpreted as effects of gas exchange between the water and the rising bubbles. Depletions of the heavy noble gases argon, krypton and xenon that were detected above an active, bubble-releasing mud volcano appear to be related to the injection of fluids depleted in noble gases that undergo vertical transport in the water column due to small density differences. In both cases, the noble gas anomalies clearly document seep-specific processes which are difficult to detect by other methods. Helium is generally enriched in the deep water of the Black Sea due to terrigenic input. Although exceptionally high helium concentrations observed in one seep area indicate a locally elevated helium flux, most of the seeps studied seem to be negligible sources of terrigenic helium. Noble gas analyses of sediment pore waters from the vicinity of a mud volcano showed large vertical gradients in helium concentrations. The helium isotope signature of the pore waters points to a crustal origin for helium, whereas the deep water of the Black Sea also contains a small mantle-type component.

  2. Noble gas anomalies and synthesis of the chemical elements

    NASA Astrophysics Data System (ADS)

    Sabu, D. D.; Manuel, O. K.

    1980-06-01

    The elemental and isotopic abundances of noble gases trapped in meteorites are discussed in relation to the origin of the chemical elements and the condensation of the solar system. The abundance patterns of the two types of planetary noble gases and of solar noble gases are examined, and it is suggested that type-X planetary noble gases, which contain isotopically anomalous argon, krypton and xenon and normal helium and neon, were derived from the outer regions of a supernova, while the Y-type planetary noble gases, which consist of isotopically normal argon, krypton and xenon, were derived from its inner regions. It is argued, however, that variations in the isotopic composition of neon can be explained by mass fraction or mass fractionation plus spallation without recourse to separate nucleogenetic anomalies. It is also concluded that the differences in the abundance patterns of planetary noble gases are primarily the result of stellar fusion reactions and adsorption, rather than gas solubility.

  3. 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

  4. 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

  5. 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.

  6. Hypothetic ?-point for noble gases

    NASA Astrophysics Data System (ADS)

    Maslov, V. P.

    2010-12-01

    In the paper, the binodal, which describes the density jump, is constructed in another way, by using the fact that the pressure in the liquid and gaseous phases coincides. The process of vitrifying the fluid, which leads to a hypothetical ?-point, is studied by using a new distribution constructed by the author in the previous paper [V. P. Maslov, "Solution of the Gibbs Paradox Using the Notion of Entropy as a Function of the Fractal Dimension," Russ. J. Math. Phys. 17 (3), 251-261 (2010)]. The application of the theory to a rather small number of particles (of the order of million) is also considered.

  7. Noble gas Records of Early Evolution of the Earth

    Microsoft Academic Search

    M. Ozima; F. A. Podoesk

    2001-01-01

    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

  8. Excimer radiation from Na-Noble-gas and K-Noble-gas molecules

    Microsoft Academic Search

    A. C. Tam; G. Moe; B. R. Bulos; W. Happer

    1976-01-01

    Emission bands from Na-noble-gas (and K-noble-gas) molecules, due to transitions between the 4ssigma (and 5ssigma) bound excited states and dissociating ground states, are observed. The noble gases used are Ar, Kr and Xe. The red shift of the emission band from the forbidden atomic s-s transition is largest for NaXe, for which it is 3055 cm-1. This NaXe band may

  9. Sub sea floor boiling of Red Sea brines: new indication from noble gas data

    Microsoft Academic Search

    Gisela Winckler; Rolf Kipfer; Reiner Botz; Mark Schmidt; Steffen Schuler; Reinhold Bayer

    2000-01-01

    Hydrothermal brines from the Atlantis II Deep, Red Sea, have been sampled in situ and analyzed for noble gases. The atmospheric noble gas concentrations (Ne, Aratm, Kr, Xe) in the deepest layer (LCL) are depleted by 20 to 30% relative to the initial concentrations in ambient Red Sea Deep Water without a systematic mass fractionation between the different noble gases.

  10. An attempt to characterize phase Q: Noble gas, Raman spectroscopy and transmission electron microscopy in residues prepared from the Allende meteorite

    NASA Astrophysics Data System (ADS)

    Matsuda, Jun-ichi; Morishita, Kazuhiko; Tsukamoto, Hidetomo; Miyakawa, Chie; Nara, Masayuki; Amari, Sachiko; Uchiyama, Tetsuya; Takeda, Seiji

    2010-09-01

    We have prepared a HF-HCl residue and its oxidized residue of the Allende meteorite and have measured the elemental concentrations and the isotopic compositions of noble gases. In the HF-HCl reside, noble gases are enriched in colloidal fraction compared to the non-colloidal fraction by a factor of 2-4. The heavy noble gases were evidently lost after the oxidization, indicating that phase Q (carrier of planetary heavy noble gases) was removed by the oxidation. The Raman spectroscopic parameters show that the colloidal fraction of the HF-HCl residue is more amorphous compared to the non-colloidal fraction. As the ion irradiation converts carbon into a more amorphous form, our result indicates that the "plasma model" is more plausible than the "labyrinth model" as the origin of phase Q. TEM (Transmission Electron Microscope) observations also show such a trace of ion irradiation. While the TEM observations did not show any large difference between the HF-HCl residue and its oxidized residue, the Raman spectroscopic parameters changed discretely resulting from the oxidization. This observation indicates that the oxidization not only dissolved and removed oxidized carbon, but also changed the carbon structure itself to a more amorphous (disordered) state. The Raman spectroscopic results indicate the possibility that release of Q-gas during oxidation is not accompanied by mass loss and that the release of Q-gas simply resulted from rearrangement of carbon structure during oxidation.

  11. 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.

  12. Numerical simulations of atmospheric releases of heavy gases over variable terrain

    SciTech Connect

    Chan, S.T.; Rodean, H.C.; Ermak, D.L.

    1982-08-01

    In this report, a three-dimensional, conservation equation model for simulating the dispersion of heavy gases has been described and used to simulate the vapor dispersion of two markedly different (regarding the role of gravity-flow) LNG spill experiments. Two numerical simulations of the NG dispersion were carried out for each experiment. The first assumed a flat terrain and the second used a numerical simulation of the actual terrain at the test site. In general, good agreement between model predictions and field measurements, regarding maximum downwind distances to the LFL, time histories of temperature and concentration at several representative locations, and concentration contours on certain horizontal and crosswind surfaces was observed. The overall results obtained in the model calculations with the simulated actual topography were shown to correlate much better with the field data and, in particular, many important features of the vapor cloud observed under the light wind conditions of Burro 8 were reproduced in the variable terrain simulation. These include the vortex-induced high concentration regions resulting in the bifurcation of the NG cloud and the deflection of the NG cloud due to sloping terrain.

  13. Noble gas study of the Saratov L4 chondrite

    NASA Astrophysics Data System (ADS)

    Matsuda, Jun-Ichi; Tsukamoto, Hidetomo; Miyakawa, Chie; Amari, Sachiko

    2010-03-01

    We have determined the elemental abundances and the isotopic compositions of noble gases in a bulk sample and an HF/HCl residue of the Saratov (L4) chondrite using stepwise heating. The Ar, Kr, and Xe concentrations in the HF/HCl residue are two orders of magnitude higher than those in the bulk sample, while He and Ne concentrations from both are comparable. The residue contains only a portion of the trapped heavy noble gases in Saratov; 40+/-9% for 36Ar, 58+/-12% for 84Kr, and 48+/-10% for 132Xe, respectively. The heavy noble gas elemental pattern in the dissolved fraction is similar to that in the residue but has high release temperatures. Xenon isotopic ratios of the HF/HCl residue indicate that there is no Xe-HL in Saratov, but Ne isotopic ratios in the HF/HCl residue lie on a straight line connecting the cosmogenic component and a composition between Ne-Q and Ne-HL. This implies that the Ne isotopic composition of Q has been changed by incorporating Ne-HL (Huss et al. 1996) or by being mass fractionated during the thermal metamorphism. However, it is most likely that the Ne-Q in Saratov is intrinsically different from this component in other meteorites. The evidence of this is a lack of correlation between the isotopic ratio of Ne-Q and petrologic types of meteorites (Busemann et al. 2000). A neutron capture effect was observed in the Kr isotopes, and this process also affected the 128Xe/132Xe ratio. The 3He and 21Ne exposure ages for the bulk sample are 33 and 35Ma, respectively.

  14. Assessment of natural dynamics and anthropogenic impacts on residence times in the urban aquifers of Recife (Brazil) using a multi-tracer approach (noble gases, CFCs, SF6, 14C)

    NASA Astrophysics Data System (ADS)

    Chatton, Eliot; Labasque, Thierry; Aquilina, Luc; Petelet-Giraud, Emmanuelle; Cary, Lise; Bertrand, Guillaume; Hochreutener, Rébecca

    2015-04-01

    The Metropolitan Region of Recife (RMR) is an urban area of the northeastern coast of Brazil located in an estuary zone and overlying a complex multi-layered sedimentary set. Over the last decades, population growth and recurrent droughts have been increasing the pressures on the aquifers of the region (over-exploitation, contamination and salinization). Through a multi-tracer approach (major and noble gases, CFCs, SF6, 14C) and the implementation of an inverse model to infer recharge conditions, the study aims to investigate the past natural dynamics of the aquifer system and to assess the impacts of the increasing withdrawals on the residence times in the aquifers. Noble gas results were implemented in an inverse model allowing the assessment the recharge conditions of the coastal aquifers of Recife. The results allowed to discriminate two types of recharge in terms of temperature and excess air. The overexploited surficial aquifer records recharge characteristics of the modern wet seasons. However, groundwaters sampled in the two underlying aquifers (Cabo and Beberibe) showed recharge temperatures below the regional minima. According to the radiocarbon dating performed in this study and previous paleotemperature studies in tropical Brazil (Stute et al., 1995), it appears that the major component of the current water supply of Recife originates from recharges dating back more than 10,000 years. Furthermore, the analysis of atmospheric tracers (CFCs, SF6) show that the exploitation of these old groundwaters has lead to a mixing with a more recent component (<50 years old) making these aquifers vulnerable to contamination and salinization.

  15. Mantle Reservoirs From a Noble Gas Perspective

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, S.

    2007-12-01

    The noble gases provide unique insight into mantle structure and the origin of the different mantle reservoirs. Many OIBs, such as Hawaii and Iceland, have 3He/4He ratios that are a factor of 4 to 6 higher than the canonical MORB value of 8±1 RA. The high 3He/4He ratios in OIBs are conventionally viewed as evidence for the existence of a primitive mantle reservoir. Such a view, however, is frequently challenged on the grounds that noble gas abundances in OIBs are an order of magnitude lower than in MORBs, an observation that traditional models of magmatic degassing cannot explain. The apparent concentration paradox has been resolved by incorporating kinetic fractionation of the noble gases during magmatic degassing of the erupting magma and it can be shown that higher CO2 and H2O content of OIBs, compared to MORBs, leads to more extensive degassing of He in OIB magmas (Gonnermann and Mukhopadhyay, 2007). In contrast to Hawaii and Iceland, some ocean islands, such as the Cook-Austral Islands and Canary Islands (HIMU ocean islands) have 3He/4He ratios of 4-7 RA, lower than the MORB range. The low 3He/4He ratios are attributed to the addition of radiogenic 4He from recycled slabs. Surprisingly, recent high-precision neon isotopic measurements made at Harvard in olivine phenocrysts from the Cook-Austral Islands indicate that HIMU neon is less nucleogenic than the MORB source. The He and Ne systematics from the Cook-Austral's demonstrate that the noble gas signature of HIMU basalts cannot arise either from simple diffusive equilibration of a recycled slab with a MORB source, or result from mixing of melts that are derived from recycled slabs and the MORB mantle. The He-Ne systematics, however, can be quantitatively modeled as a mixture of recycled slab and a primitive mantle reservoir. The scenario is consistent with He-Os and He- Nd correlations seen in the Cook-Austral basalts. Thus, both low and high 3He/4He OIBs incorporate the same primitive mantle reservoir, although in varying proportions. The notion of a reservoir that is primitive in its volatile content and sampled at ocean islands is very much alive. In spite of whole mantle convection, it appears that part of the Earth's mantle has remained largely undegassed. While significant progress has been made with respect to understanding the geochemical implications of He and Ne isotopic composition measured in MORBs and OIBs, our knowledge of Xenon in the mantle remains poor. Since 129Xe and 136Xe have been produced by the now extinct nuclides, 129I and 244Pu respectively, Xe isotopic composition of the mantle can be used to test models of atmosphere formation and provide unique clues to the volatile history of the Earth's mantle. Some of the outstanding issues that still need to be resolved are whether the Earth's mantle has solar or chondritic heavy noble gases, whether OIBs and MORB have the same Xe isotopic composition, and what fraction of the 136Xe is from 244Pu vs. 238U fission. Addressing these issues will require not only high precision measurements but also innovative experimental techniques to reduce air contamination that is ubiquitous in mantle-derived samples. High precision Xe isotopic measurements made at Harvard indicates that Samoa (a high 3He/4He ocean island) and MORBs have exactly the same proportion of radiogenic 129Xe to 136Xe. Although this result needs to be verified from other OIBs, it suggests that a single mantle reservoir supplies the excess 129Xe and 136Xe to both the MORB and OIB mantle source. The primitive mantle reservoir is the most likely carrier of the xenon isotopic anomaly.

  16. 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

  17. Applications of noble gas NMR to condensed matter systems

    Microsoft Academic Search

    C.-H. Tseng; R. W. Mair; G. P. Wong; R. L. Walsworth; S. Patz; D. Williamson; M. D. Hurlimann; L. M. Schwartz; D. G. Cory

    1998-01-01

    The spin-off of laser-polarized noble gases (^3He and ^129Xe) from atomic physics to biomedical imaging has renewed interest in gas-phase NMR and MRI. We are applying noble gas NMR to studies of condensed matter systems such as porous media and liquid xenon. NMR measurements of restricted noble gas diffusion in porous media offer two important advantages over conventional (liquid) NMR

  18. Noble Gases in a Metal Separate of the Solar-Gas Rich Meteorite Fayetteville, Released by Closed System Oxidation with CuCl2xnH2O

    NASA Astrophysics Data System (ADS)

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

    1992-07-01

    Closed system stepped oxidation of noble gas-rich samples at room-temperature leads to less diffusive elemental fractionation during gas-release than techniques involving high temperatures like stepped combustion or pyrolysis. Metal is generally considered to retain noble gases even better than ilmenite. Thus regolithic metal samples are likely to contain the least fractionated solar noble gases. A metal separate of the dark portion of the Fayetteville (H4-6) chondrite that contained visible amounts (~25 vol%) of attached silicates was oxidized with CuCl(sub)2xnH2O-solutions (first proposed by Vilcsek and Wanke, 1965) in a pyrex-glass extraction line. Average procedural and reagent blank values for a typical step duration of one hour are [in 10^-10 cm^3 STP]: ^4He = 500; ^20Ne = 0.7; ^40Ar = 95. Here we report data of a preliminary experiment obtained on a small 9.2 mg sample, subjected to increasingly aggressive solutions. Blank corrections are substantial and only 5 steps yielded meaningful data. At the conference, we will present results of a considerably larger Fayetteville metal sample. The Ne isotopic data are rather similar to CSSE data of ilmenite, pyroxene, and plagioclase separates from lunar soils (Wieler et al., 1986; Wieler et al., 1987; Benkert et al., 1988). (^20Ne/^22Ne)(sub)tr starts at 13.1 and decreases to 11.6. The latter value is close to the SEP-Ne point (^20Ne/^22Ne ~ 11.3 +- 0.3) indicating that we succeeded to isolate SEP-Ne in rather pure form from Fayetteville metal. The first CSSE steps release isotopically slightly heavier Ne than the first combustion steps of a Weston metal separate analyzed by Becker and Pepin (1991), whereas in the last CSSE steps Ne is consideribly closer to the SEP composition than in the last combustion/pyrolysis steps. The air corrected ^36Ar/^38Ar ratios range between 4.0 to 2.6 (assuming all ^40Ar to be atmospheric). These values are clearly lower than the ratio of SW-Ar and SEP-Ar of ~5.5 and ~4.9, respectively, and show that cosmogenic Ar interfered severely. Only a more gentle etching at the start of the run could possibly reveal the undisturbed SW-Ar signature. Due to cosmogenic ^3He we can also not derive a (^3He/^4He)(sub)tr value from our first data set. The ^20Ne/^36Ar ratio corrected for air Ar and to first order also for cosmogenic Ar is between 40 and 50 in all steps with uncertainties of 5 to 10%. This is within error identical to the solar wind value of 45 +- 10 and indicates that Fayetteville metal indeed retains rather unfractionated solar Ne and Ar. Similar ^20Ne/^36Ar values were also observed in Weston metal (Becker and Pepin, 1991). In the first two steps corrected ^4He/^36Ar ratios are 15000 and 21000, respectively, close to the solar wind value of 25000, but later this ratio decreases to 8000, which is not yet well understood. We see no evidence for (^4He/^36Ar)(sub)sw = 36000 as claimed for Weston metal (Becker and Pepin, 1991). This pilot experiment indicates that solar wind gases in metal indeed are even less disturbed by diffusion than in ilmenites and further underscores the existence of SEP noble gases as an independent component in the solar corpuscular radiation. Work supported by the Swiss National Science Foundation. References: Becker R.H. and Pepin R.O. (1991) Earth Planet. Sci. Lett. 103, 55-68. Benkert J.P. et al. (1988) Lunar Planet. Sci. (abstract) 19, 59. Geiss J. et al. (1972) NASA SP-315, 14.1- 14.10. Wieler R. et al. (1986) Geochim. Cosmochim. Acta 50, 1997- 2017. Wieler R. et al. (1987) Lunar Planet. Sci. (abstract) 18, 1080. Vilcsek E. and Wanke H. (1965) Z. Naturforsch. 20a, 1282.

  19. 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)

  20. Nitrogen is Not Always Noble in the Mantle

    NASA Astrophysics Data System (ADS)

    Mikhail, S.; Sverjensky, D. A.

    2014-12-01

    Tracing volatiles through the subduction system is pivotal for understanding the long-term evolution of the Earth's atmosphere. To this regard, the ratio of molecular nitrogen over one or more of the noble gases is a commonly employed method, but is based on the assumption that nitrogen is a highly incompatible element and behaves as a noble gas. Thus, to compare nitrogen/noble gas data from volcanic arcs on a global scale requires the behaviour of nitrogen relative to the noble gases to be constant. We have calculated the speciation of nitrogen in equilibrium with eclogite (jadeite + kyanite + coesite) and peridotite (enstatite + forsterite) under lower crustal and upper mantle conditions (500-1,000°C & 1-5 GPa) and over several redox states (QFM +3 to -6) and pH values (0-8). Our data demonstrates the duality for the behaviour of nitrogen during subduction, where nitrogen can either behave either as a noble gas (N2) or as a moderately compatible element in K-bearing phases (NH4+). Estimations for volatile abundance and fluxes based on N2/noble gas systematics are potentially flawed, and datasets for N2/noble gas systematics between different arc systems are not intuitively comparable (on the global scale). These data are also used to discuss the partitioning behaviour of nitrogen relative to other volatiles, such as carbon, and the noble gases.

  1. Noble-Gas Distribution in the Murchison, Murray, Nogoya and Yamato791198 CM Chondrites

    Microsoft Academic Search

    T. Nakamura; K. Metzler; K. Nagao; N. Takaoka

    1996-01-01

    Laser-spot analysis was carried out on the Murchison, Murray, Nogoya, and Yamato (Y)-791198 CM chondrites in order to see microdistribution of noble gases. Primordial noble gases are rich in rims around chondrules in the four meteorites. This suggests that large fractions of the primordial noble-gas carrier phases in the CM chondrites might have accreted on chondrules prior to formation of

  2. Noble gas composition of the solar wind as collected by the Genesis mission

    Microsoft Academic Search

    Veronika S. Heber; Rainer Wieler; Heinrich Baur; Chad Olinger; Tom A. Friedmann; Donald S. Burnett

    2009-01-01

    We present the elemental and isotopic composition of noble gases in the bulk solar wind collected by the NASA Genesis sample return mission. He, Ne, and Ar were analyzed in diamond-like carbon on a silicon substrate (DOS) and 84,86Kr and 129,132Xe in silicon targets by UV laser ablation noble gas mass spectrometry. Solar wind noble gases are quantitatively retained in

  3. Recent progress in modeling the atmospheric dispersion of heavy gases over variable terrain using the three-dimensional conservation equations

    SciTech Connect

    Chan, S. T.; Ermak, D. L.

    1983-08-01

    In this paper, a three-dimensional, conservation equation model for simulating the atmospheric dispersion of heavy gases has been briefly described; the model was successfully applied and assessed via simulating three distinctly different LNG spill experiments. These experiments involve approximately 30 m/sup 3/ LNG spills, with atmospheric conditions ranging from slightly stable to slightly unstable (ambient wind speed from about 2 m/s to 10 m/s). In general, good agreement between model predictions and field measurements was observed in all cases based on comparing, among others, the maximum concentrations as a function of downwind distance, the maximum downwind distances to the LFL, time histories of concentration at specific locations, and concentration contours on certain horizontal and crosswind surfaces. In particular, the overall results obtained in the model calculations with the simulated actual topography were shown to correlate much better with the field data in that many important features of the vapor cloud observed under the light wind conditions of Burro 8 were successfully reproduced. These include the spreading of vapor cloud in all directions (in upwind direction as well), the vortex-induced high concentration regions, the bifurcation of the NG cloud, and the deflection of the NG cloud due to sloping terrain. Through the present numerical simulations, the effects of variable terrain on the dispersion of heavy gases have been clearly demonstrated. Even with the relatively mild terrain at the test site and under a moderately high wind speed of approx. 6 m/s (Burro 9), the resulting vapor cloud dispersion was seen to differ noticeably from that using a flat terrain assumption. The combined effects of large gravity-flow (relative to the mean wind) over variable terrain and under light wind conditions (Burro 8) were shown to be even more profound. In such gravity-flow dominated regimes, proper treatment of the terrain, if present, is obviously necessary.

  4. 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

  5. Three-dimensional model for simulating atmospheric dispersion of heavy-gases over complex terrain

    SciTech Connect

    Chan, S.T.

    1997-09-01

    To help understand heavy gas releases and simulate the resultant dispersion, we have developed a three-dimensional finite element model called FEM3 and an improved version names FEM3A for solving the time dependent conservation equations based on generalized anelastic approximation. Recent enhancements to the model to include the treatment of dispersion scenarios involving density variations much larger than the liquefied natural gas range and an advanced turbulence submodel based on the buoyancy-extended transport equations. This paper presents the main features of the present model FEM3C and numerical results from the simulations of a field-scale LNG spill experiment.

  6. Medical Imaging with Laser Polarized Noble Gases

    Microsoft Academic Search

    Timothy Chupp

    2000-01-01

    In the past five years, techniques of magnetic resonance imaging with laser polarized ^3He and ^129Xe have emerged along with the promise of entirely new ways to use NMR information from gas in the lungs and of xenon dissolved in tissue. This marriage of laser\\/optical physics and medical imaging has the potential to provide new ways to study and map

  7. New applications of laser-polarized noble gas NMR

    Microsoft Academic Search

    R. L. Walsworth

    1999-01-01

    Laser optical pumping techniques greatly enhance the NMR detection sensitivity of the spin 1\\/2 noble gases (3He and 129Xe), with novel applications in both the biomedical and physical sciences. I will discuss new research activities by my group and collaborators using laser polarized noble gas NMR: gas-space imaging at both high and low magnetic fields; imaging of liquid xenon and

  8. Study of lasing and discharge plasma parameters in noble gas\\/metal atom mixtures

    Microsoft Academic Search

    Tadeusz M. Adamowicz

    2003-01-01

    Results of research on metal ion lasers are presented. They were obtained using novel diagnostic methods for measurements lasing parameters of noble gas-metal vapor systems and determination of metal atom diffusion coefficients in noble gases. Influence of helium 3He isotope on plasma and laser parameters in He-noble gas and metal atom mixtures was studied as well as some elementary processes

  9. 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.

  10. On the accuracy of noble gas recharge temperatures as a paleoclimate proxy

    Microsoft Academic Search

    Bradley D. Cey

    2009-01-01

    Dissolved noble gases in groundwater are an important terrestrial temperature proxy for the last glacial maximum (LGM). Noble gas temperatures (NGT) provide a record of long-term mean water table temperature (WTT) during groundwater recharge. For NGT to accurately represent surface air temperatures (SAT), the difference between mean annual air temperature (MAAT) and WTT must be known through time. Many paleoclimate

  11. REVIEW ARTICLE: Method for counting noble gas atoms with isotopic selectivity

    Microsoft Academic Search

    G. S. Hurst; M. G. Payne; S. D. Kramer; C. H. Chen; R. C. Phillips; S. L. Allman; G. D. Alton; J. W. T. Dabbs; R. D. Willis; B. E. Lehmann

    1985-01-01

    A method has been developed for direct counting of noble gas atoms and has been demonstrated for selected isotopes of krypton. In principle, a few atoms of the noble gases argon, krypton, xenon and radon can now be counted with isotopic selectivity whether stable or radioactive. A concept was originated in which a laser method would be used to count

  12. 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...

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

    E-print Network

    Jacob C. McComb; Michael A. Coplan; Mohamed al-Sheikhly; Alan K. Thompson; Robert E. Vest; Charles W. Clark

    2014-03-24

    Far-ultraviolet (FUV) scintillation signals have been measured in heavy noble gases (argon, krypton, xenon) following boron-neutron capture ($^{10}$B($n,\\alpha$)$^7$Li) in $^{10}$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 $^{10}$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 $^{10}$B($n,\\alpha$)$^7$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 $^{10}$B($n,\\alpha$)$^7$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 $^{10}$B thin films due to higher average energy loss of the $^{10}$B($n,\\alpha$)$^7$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.

  14. Noble gas geochemistry in thermal springs

    SciTech Connect

    Kennedy, B.M.; Reynolds, J.H. (Univ. of California, Berkeley (USA)); Smith, S.P. (Charles Evans and Associates, Redwood City, CA (USA))

    1988-07-01

    The composition of noble gases in both gas and water samples collected from Horseshoe Spring, Yellowstone National Park, was found to be depth dependent. The deeper the sample collection within the spring, the greater the enrichment in Kr, Xe, radiogenic {sup 4}He, and {sup 40}Ar and the greater the depletion in Ne relative to {sup 36}Ar. The compositional variations are consistent with multi-component mixing. The dominant component consists of dissolved atmospheric gases acquired by the pool at the surface in contact with air. This component is mixed in varying degree with two other components, one each for gas and water entering the bottom of the pool. The two bottom components are not in equilibrium. In Horseshoe Spring, the bubbles entering at the bottom strip the atmospheric-derived pool gases from the surrounding water while en route to the surface. If the original bottom bubbles are noble gas, as in the case of Horseshoe, the acquired pool gases can then quickly obliterate the original bubble composition. These results are used to demonstrate that Yellowstone spring surface gas samples, and perhaps similarity sampled thermal springs from other hydrothermal systems, have gas abundances that depend more on spring morphology than processes occurring deeper in the hydrothermal system.

  15. Determining noble gas partitioning within a CO2-H2O system at elevated temperatures and pressures

    NASA Astrophysics Data System (ADS)

    Warr, Oliver; Rochelle, Christopher A.; Masters, Andrew; Ballentine, Christopher J.

    2015-06-01

    Quantifying the distribution of noble gases between phases is essential for using these inert trace gases to track the processes controlling multi-phase subsurface systems. Here we present experimental data that defines noble gas partitioning for two phase CO2-water systems. These are at the pressure and temperature range relevant for engineered systems used for anthropogenic carbon capture and geological storage (CCS) technologies, and CO2-rich natural gas reservoirs (CO2 density range 169-656 kg/m3 at 323-377 K and 89-134 bar). The new partitioning data are compared to predictions of noble gas partitioning determined in low-pressure, pure noble gas-water systems for all noble gases except neon and radon. At low CO2 density there was no difference between measured noble gas partitioning and that predicted in pure noble gas-water systems. At high CO2 density, however, partition coefficients express significant deviation from pure noble gas-water systems. At 656 kg/m3, these deviations are -35%, 74%, 113% and 319% for helium, argon, krypton and xenon, respectively. A second order polynomial fit to the data for each noble gas describes the deviation from the pure noble gas-water system as a function of CO2 density. We argue that the difference between pure noble gas-water systems and the high density CO2-water system is due to an enhanced degree of molecular interactions occurring within the dense CO2 phase due to the combined effect of inductive and dispersive forces acting on the noble gases. As the magnitude of these forces are related to the size and polarisability of each noble gas, xenon followed by krypton and argon become significantly more soluble within dense CO2. In the case of helium repulsive forces dominate and so it becomes less soluble as a function of CO2 density.

  16. Polarization Optimization for Laser Polarized Noble Gas MR Studies

    Microsoft Academic Search

    K. P. Coulter; M. S. Rosen; R. C. Welsh; S. D. Swanson; T. E. Chupp

    1996-01-01

    The efficacy of laser polarized noble gas Magnetic Resonance (MR) imaging and spectroscopy depends critically on the ability to produce large magnetizations of the gases used. While signal size is directly related to both the polarization and concentration of the gas, sufficient volumes of gas can also allow studies to be done which examine the time dependence of the biological

  17. Noble Gas Analysis for the OMEGA Gas Sampling System

    Microsoft Academic Search

    G. T. Young; S. M. Hupcher; C. G. Freeman; M. A. Stoyer; T. C. Sangster

    2007-01-01

    The OMEGA Gas Sampling System (OGSS) at the Laboratory for Laser Energetics can be used to study a wide variety of implosion parameters in inertial confinement fusion. By doping a target capsule with carefully chosen detector nuclei, nuclear reactions between fusion products and detector nuclei can produce noble gas isotopes. Following a capsule implosion, these gases are pumped out of

  18. 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

  19. Changes in the Noble Gas Pattern of Hot Desert Meteorites Caused by Weathering - Correlation with Terrestrial Age and Weathering Grade

    NASA Astrophysics Data System (ADS)

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

    1996-03-01

    We present new noble gas data on 11 ordinary H-chondrites from the Acfer region and one from Roosevelt County that confirm earlier results and provide additional information about the coherence of atmospheric noble gas contamination with the degree of weathering and terrestrial age. To study the compositional variations in heavily weathered meteorites in more detail, noble gases in four of these chondrites are determined from interior and exterior sections of the same specimen.

  20. Noble alloys in dentistry.

    PubMed

    Gettleman, L

    1991-04-01

    Noble metals used for dental castings continue to consist of alloys of gold, palladium, and silver (not a noble metal), with smaller amounts of iridium, ruthenium, and platinum. The majority are used as a backing for ceramic baking, with the rest used as inlays, onlays, and unveneered crowns. Base metal alloys, principally made of nickel, chromium, and beryllium have gained widespread usage, especially in the United States, due to their lower cost and higher mechanical properties. The current literature, for the most part, cites the use of noble alloys as controls for trials of alternative materials. Direct gold (gold foil) still retains a following and a number of new patents were founded. PMID:1777669

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

    E-print Network

    McComb, Jacob C; al-Sheikhly, Mohamed; Thompson, Alan K; Vest, Robert E; Clark, Charles W

    2014-01-01

    Far-ultraviolet (FUV) scintillation signals have been measured in heavy noble gases (argon, krypton, xenon) following boron-neutron capture ($^{10}$B($n,\\alpha$)$^7$Li) in $^{10}$B thin films. The observed scintillation yields are comparable to the yields from some liquid and solid neutron scintillators. At noble gas pressures of 10$^7$ kPa, the number of photons produced per neutron absorbed following irradiation of a 1200 nm thick $^{10}$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 $^{10}$B($n,\\alpha$...

  2. 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.

  3. Noble gas isotopic composition as a key reference parameter in a planetary atmospheric evolution model

    NASA Astrophysics Data System (ADS)

    Ozima, M.

    2010-12-01

    The isotopic composition of noble gases is a key reference parameter in discussing the evolution of planetary atmospheres. Currently, two widely occurring noble gas components are identified in the early solar system, one is the Solar Wind noble gas (SW-noble gas, hereafter) and another is the Q-noble gas in unaltered meteorites: both noble gases are characterized by their ubiquitous occurrence and high isotopic homogeneity. Since the SW-noble gas is directly ejected from the Sun, it has been assumed to be a good proxy of the average noble gas isotopic composition in the Sun, namely the solar noble gas. The systematic enrichment of the heavier isotopes in the Q-noble gas relative to the SW-noble gas is then commonly attributed to its isotopic fractionation from the SW-noble gas. However, the isotopic compositions of the SW-noble gas either implanted on lunar soils or trapped by artificial targets show considerable isotopic variation depending on the velocity of the Solar Wind. Therefore, it is important to examine how closely the SW-noble gas represents the indigenous solar noble gas component or the mean isotopic composition of noble gases of the Sun. Here we show that the isotopic composition of the SW-noble gas is substantially fractionated relative to the solar value, and therefore should not be used as a reference parameter. We further suggest that the post D-burning Q-noble gas (see below) is the better proxy of the solar noble gas, and this should be used as a reference of the Solar noble gas isotopic composition in discussing the planetary atmospheric evolution. The most distinct difference between the Q- and the SW-noble gas is apparent in a 3He/4He isotopic ratio: 4.64e-4 in Q-He [1], but 1.23e-4 in SW-He[2]. The difference is attributed to the conversion of deuteron (D) to 3He in the Sun, namely the D-burning [3], due to high temperature during the pre-main sequence stage of the Sun. With the use of recent data on D/H ratios from helio-seismology [4] and spectroscopic observation of the inter-stellar cloud [5], we estimated that the 3He/4He ratio in the post D-burning He in the Sun is 3.98e-4. The latter value is considerably smaller than the recent estimate of the SW-He ratio by the GENESIS mission of 3He/4He = 4.64e-4 [2]. We conclude that this difference is due to isotopic fractionation during the ejection of the Solar Wind from the solar atmosphere. The further interesting implication of this conclusion is that the marked difference in 3He/4He between the SW- and Q-noble gases can be used as an unique chronological marker in the planetary atmospheric evolution. [1] Busemann H. et al., Meteoritics & Planetary Science, 35, 949-973, 2000. [2] Heber V. et al. Geochimica Cosmochimica Acta, 73, 7414-7432, 2009. [3] Geiss J. and Reeve H. Astronomy Astrophysics, 18, 126-132, 1972. [4] Basu S. and Antia H.M. Astrophysical J. , 606:L85-L88, 2004. [5] Linsky J.L. et al. Astrophysical J., 647:1106-1124, 2006.

  4. Noble metal ionic catalysts.

    PubMed

    Hegde, M S; Madras, Giridhar; Patil, K C

    2009-06-16

    Because of growing environmental concerns and increasingly stringent regulations governing auto emissions, new more efficient exhaust catalysts are needed to reduce the amount of pollutants released from internal combustion engines. To accomplish this goal, the major pollutants in exhaust-CO, NO(x), and unburned hydrocarbons-need to be fully converted to CO(2), N(2), and H(2)O. Most exhaust catalysts contain nanocrystalline noble metals (Pt, Pd, Rh) dispersed on oxide supports such as Al(2)O(3) or SiO(2) promoted by CeO(2). However, in conventional catalysts, only the surface atoms of the noble metal particles serve as adsorption sites, and even in 4-6 nm metal particles, only 1/4 to 1/5 of the total noble metal atoms are utilized for catalytic conversion. The complete dispersion of noble metals can be achieved only as ions within an oxide support. In this Account, we describe a novel solution to this dispersion problem: a new solution combustion method for synthesizing dispersed noble metal ionic catalysts. We have synthesized nanocrystalline, single-phase Ce(1-x)M(x)O(2-delta) and Ce(1-x-y)Ti(y)M(x)O(2-delta) (M = Pt, Pd, Rh; x = 0.01-0.02, delta approximately x, y = 0.15-0.25) oxides in fluorite structure. In these oxide catalysts, Pt(2+), Pd(2+), or Rh(3+) ions are substituted only to the extent of 1-2% of Ce(4+) ion. Lower-valent noble metal ion substitution in CeO(2) creates oxygen vacancies. Reducing molecules (CO, H(2), NH(3)) are adsorbed onto electron-deficient noble metal ions, while oxidizing (O(2), NO) molecules are absorbed onto electron-rich oxide ion vacancy sites. The rates of CO and hydrocarbon oxidation and NO(x) reduction (with >80% N(2) selectivity) are 15-30 times higher in the presence of these ionic catalysts than when the same amount of noble metal loaded on an oxide support is used. Catalysts with palladium ion dispersed in CeO(2) or Ce(1-x)Ti(x)O(2) were far superior to Pt or Rh ionic catalysts. Therefore, we have demonstrated that the more expensive Pt and Rh metals are not necessary in exhaust catalysts. We have also grown these nanocrystalline ionic catalysts on ceramic cordierite and have reproduced the results we observed in powder material on the honeycomb catalytic converter. Oxygen in a CeO(2) lattice is activated by the substitution of Ti ion, as well as noble metal ions. Because this substitution creates longer Ti-O and M-O bonds relative to the average Ce-O bond within the lattice, the materials facilitate high oxygen storage and release. The interaction among M(0)/M(n+), Ce(4+)/Ce(3+), and Ti(4+)/Ti(3+) redox couples leads to the promoting action of CeO(2), activation of lattice oxygen and high oxygen storage capacity, metal support interaction, and high rates of catalytic activity in exhaust catalysis. PMID:19425544

  5. Manure Gases

    MedlinePLUS

    ... The gases of most concern are ammonia and hydrogen sulfide. Other gases of concern include methane and ... present? Since most of these gases in particular hydrogen sulfide are heavier-than-air, they tend to ...

  6. Polarization optimization for laser polarized noble gas MR studies

    SciTech Connect

    Coulter, K.P.; Rosen, M.S.; Welsh, R.C.; Swanson, S.D.; Chupp, T.E. [Univ. of Michigan, Ann Arbor, MI (United States)

    1996-05-01

    The efficacy of laser polarized noble gas Magnetic Resonance (MR) imaging and spectroscopy depends critically on the ability to produce large magnetizations of the gases used. While signal size is directly related to both the polarization and concentration of the gas, sufficient volumes of gas can also allow studies to be done which examine the time dependence of the biological uptake of polarized noble gas. The authors have undertaken MR imaging and spectroscopy studies with Xe and He. These studies have concentrated on the use of high power laser diode arrays (LDAs) as the most practical means to produce large magnetizations. They discuss the technique and optimization of polarized noble gas production for these medical imaging and spectroscopy experiments.

  7. SLAB: a time-dependent computer model for the dispersion of heavy gases released in the atmosphere

    SciTech Connect

    Morgan, D.L. Jr.; Morris, L.K.; Ermak, D.L.

    1983-01-20

    The SLAB model describes the dispersion and gravity flow of a heavy gas released into the atmosphere at ground level, using a crosswind-averaged form of the conservation equations of mass, momentum, species, and energy. The model is time-dependent and one-dimensional in that the equations depend on only one spatial dimension, downwind distance. On the other hand, the model is quasi-three-dimensional since it contains equations to determine the crosswind dimensions of the dispersing cloud. Specific submodels are included to describe wind speed as a function of height, air entrainment into the cloud as the result of turbulent mixing, and heat and momentum flow between the cloud and the ground beneath it and the air surrounding it. The SLAB computer code determines the properties of the dispersing heavy-gas cloud by employing the method of lines to numerically integrate the partial differential equations that comprise the model.

  8. Pressure broadening and frequency shift of the 5S1/2 ? 5D5/2 and 5S1/2 ? 7S1/2 two photon transitions in 85Rb by the noble gases and N2

    NASA Astrophysics Data System (ADS)

    Zameroski, Nathan D.; Hager, Gordon D.; Erickson, Christopher J.; Burke, John H.

    2014-11-01

    Doppler free two photon absorption spectroscopy was employed to measure the pressure broadening and frequency shift rates of the 5S1/2 (F = 3) ? 5D5/2 (F = 5, 4, 3, 2, 1) (778.105 nm) and the 5S1/2 (F = 2) ? 7S1/2 (F = 2) (760.126 nm) two photon transitions in 85Rb by the noble gases and N2. To our knowledge, these rates are reported on for the first time. The self-broadening and shift rate of the 5S1/2 (F = 3) ? 5D5/2 (F = 5, 4, 3, 2, 1) transition and self -broadening rate of the 5S1/2 (F = 2) ? 7S1/2 (F = 2) transition were also measured. The temperature dependence of the self-frequency shift (Rb-Rb collisions) of these transitions is presented. Helium diffusion rates through Quartz and Pyrex cells are also calculated and the implication of helium diffusion through glass vapor cells is discussed in regards to atomic frequency standards based on these transitions. Experimental pressure broadening and shift rates are compared to theoretically calculated rates assuming a 6, 8 or 6, 8, 10 difference potential and pseudo potential model. Reasonable agreement is achieved between experimental and theoretical values.

  9. An overview of noble gas (He, Ne, Ar, Xe) contents and isotope signals in terrestrial diamond

    NASA Astrophysics Data System (ADS)

    Basu, S.; Jones, A. P.; Verchovsky, A. B.; Kelley, S. P.; Stuart, F. M.

    2013-11-01

    The noble gas geochemistry of different types of terrestrial diamond including coated stones, alluvial diamonds, framesites, carbonados and impact diamonds yields a wealth of information on the sources of volatiles responsible for diamond formation. We present an illustrated compilation of published analyses of noble gases in different types of natural diamond. Noble gases in diamond record primary signatures from the mantle indicative of their integrated sources, and, the contribution of different metasomatic agents including subducting fluids and kimberlitic melt sampled during diamond growth. In addition, they show evidence of secondary processes such as resorption. Most data are available for coated stones, which trap abundant volatile-rich microscopic inclusions in their rims. While the coated stones are dominated by Mid-Oceanic-Ridge-Basalt (MORB) type noble gas signatures, the other diamond types contain predominantly crustal and atmospheric components although some mantle gases may be present, the latter indicated in elevated 20Ne/22Ne and/or 129Xe/132Xe ratios relative to atmospheric values. Some alluvial diamonds have very high 3He/4He that may represent the presence of a solar component trapped during their formation, but are just as likely to be the result of cosmogenic 3He implantation during their prolonged residence at the Earth's surface. Oceanic-Island-Basalt (OIB) type noble gases occur in nanometer sized inclusions in metamorphic diamond from Kazakhstan, yet their significance as a fingerprint of mantle processes is not fully understood. Implanted noble gases occur near the outer surfaces of individual crystals, and are generally not a major hindrance for the study of mantle signatures, except for polycrystalline diamond like framesites with small grain size. Some diamonds including the polycrystalline carbonados, are dominated by crustal noble gases with no discernible mantle component evidenced by very low 3He/4He and 20Ne/22Ne ratios, and very high 21Ne/22Ne and 131,134,136Xe/132Xe ratios. In many diamonds, variations in both concentration and isotopic composition within samples from the same geographical location require complex diamond growth. For example, coated stones of Zaire trap noble gases from multiple sources and different generations of diamond growth. Thus noble gas studies have the potential to record major processes during the complex growth histories of natural diamond and also to provide valuable information about the sub-continental mantle. Noble gas signatures may be affected by diffusive losses, notably in some framesites.

  10. Noble Gas Signatures in Greenland - Tracing Glacial Meltwater Sources

    NASA Astrophysics Data System (ADS)

    Niu, Y.; Castro, M. C.; Hall, C. M.; Aciego, S.; Stevenson, E. I.; Arendt, C. A.

    2014-12-01

    This study is meant to explore the information noble gases can provide in glacial environments with respect to glacial meltwater sources, relative source contributions, water residence times, and spatial location where this glacial meltwater originates in the ice sheet. Ultimately, we seek to improve our understanding on the dynamics of these massive ice sheets, critical for the major role they play on climate change. This is possible due to the conservative nature of noble gases and temperature dependency of their concentrations in water in equilibrium with the atmosphere (ASW) allowing for calculation of noble gas temperatures (NGTs) and, under certain assumptions, estimation of the altitude at which glacial meltwater originated. In addition, crustally produced isotopes such as He accumulate in water over time, allowing for estimation of water residence times. Glacial meltwater samples were collected and analyzed for noble gas concentrations and isotopic ratios at five different locations in southern Greenland, between sea level and 1221 m. All samples are enriched in He with respect to ASW and are depleted in all other noble gases. Two patterns are apparent. The first one presents a relative Ar enrichment with respect to Ne, Kr, and Xe, a pattern first observed in high-altitude springs in the Galápagos Islands. The second one displays a mass-dependent pattern, a pattern first observed in Michigan rainwater samples. Most samples point to equilibration temperatures at ~0°C and altitudes between 1000 m and 2000 m, values which are consistent with both temperatures and elevations in Greenland. He concentrations vary between 1.1 and 7 times that of ASW and suggest glacial meltwater ages between ~170 and 1150 yrs, a result which is consistent with a preliminary tritium analysis. He isotopes point to surface (precipitation as snow and rainfall) contributions for most samples between ~60% and 90% with a ~10% - 40% crustal contribution from groundwater.

  11. 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.

  12. Experimental Study of Noble Gas Partitioning and Diffusion in Common Crustal Minerals

    Microsoft Academic Search

    P. L. Clay; E. F. Baxter; S. P. Kelley; E. B. Watson; J. B. Thomas; D. J. Cherniak

    2005-01-01

    Recent study [e.g. 1,2,3] has shown that the partitioning of noble gases amongst system phases (including minerals, fluids, and grain boundaries) is fundamental to thermochronologic models and interpretations of the commonly used K\\/Ar and U-Th\\/He decay systems. However, little direct data on noble gas partitioning between common minerals of the crust exists. We have investigated two experimental methods to measure

  13. Vesiculation, melt formation, noble gas/nitrogen behaviour, and impact chronology on a planetary regolith : the case of Benccubbin (CB) meteorite

    NASA Astrophysics Data System (ADS)

    Marty, B.; Turner, G.; Kelley, S. P.

    2008-12-01

    The Benccubbin meteorite is a member of the CB peculiar meteorite family, which all have reduced silicates, metal zoning, solar Ni/Co and large enrichments in 15N, that have been regarded as relics of their very primitive character. However, these meteorites also show tugsten isotopic ratios suggesting metal differentiation events several Ma after start of solar system formation. The Benccubbin mineralogy is best explained as being an heterogeneous planetary regolith containing clasts of different origins (e.g., CO, CI chondrules and clasts, silicates of unknown origin). This meteorite presents evidence of having been impacted, such as melt, temperature gradient recorded at the silicate/metal interface, and textures indicative of rapid cooling. Notably, Benccubbin contains vesicles in several phases : partially molten silicate clasts and CO chondrules, impact melt, and the so-called bubble grains 1. We have analysed several Benccubbin mineral and metal phases for N and noble gas isotopes and abundances by both laser fusion and vacuum crushing. 15N-rich nitrogen (d15N up to +1,000 per mil) is ubiquituous, particularly inside vesicles, and is associated with noble gases. Notably, N and noble gases appear to have largely exchanged between silicate and vesicles, reaching locally equilibrium partitioning. Gases are still released after extensive crushing up to 4,000 strokes, in contrast to the case of MORB glasses and suggesting a foam-like, decompression structure of the impacted melt. N and Ar correlate well, showing that the N solubility was comparable to that of Ar and therefore that the redox conditions were above IW, according to 2. From the N content of the glass, we estimate that it equilibrated with a vapor plume in which the pressure of nitrogen was ~300 Bar. Radiogenic 40Ar is present inside the vesicles, showing that the vesiculation event was not an early process. Ar-Ar dating of Benccubbin suggests involvement in an impact around 4.2 Ga. In contrast to very variable N and primordial noble gas contents among different phases, cosmogenic 3He, 21Ne and 38Ar abundances are uniform, and vesicles contain little cosmogenic isotopes, showing that space exposure occurred after the vesicle forming impact event. Hence the event that led to the ejection of the Benccubbin meteorite was distinct from the vesiculation one, and occurred 40-50 Ma ago according to cosmogenic 3He, 21Ne and 38Ar isotopes and 38Ar-37Ar correlation. Noble gases have been well preserved in vesicles from cosmic ray isotope contributions, permitting to determine their origin precisely despite extensive exposure in space. Noble gases present Q-like isotopic ratios but highly fractionated abundances with respect to Q. The fact that comets are definitely rich in 15N 3 and may also have Q-like noble gas signature in their refractory phases 4 is suggestive of a possible link between cometary matter and CBs. 1. Perron, C., Fieni, C. and Guilhaumou, N. Geochim.Cosmochim. Acta 72, 959-977 (2008). 2. Libourel, G., Marty, B. and Humbert, F. Geochim. Cosmochim. Acta 67, 4123-4135 (2003). 3. Bockelee-Morvan, D. et al. Large excess of heavy nitrogen in both hydrogen cyanide and cyanogen from comet 17P/Holmes. Ap J.679, L49-L52 (2008). 4. Marty, B. et al. Science 319, 75-78 (2008).

  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. Light noble gas dissolution into ring structure-bearing materials and lattice influences on noble gas recycling

    NASA Astrophysics Data System (ADS)

    Jackson, Colin R. M.; Parman, Stephen W.; Kelley, Simon P.; Cooper, Reid F.

    2015-06-01

    Light noble gas (He-Ne-Ar) solubility has been experimentally determined in a range of materials with six-member, tetrahedral ring structures: beryl, cordierite, tourmaline, antigorite, muscovite, F-phlogopite, actinolite, and pargasite. Helium solubility in these materials is relatively high, 4 × 10-10 to 3 × 10-7 mol g-1 bar-1, which is ?100 to 100,000× greater than He solubility in olivine, pyroxene, or spinel. Helium solubility broadly correlates with the topology of ring structures within different minerals. Distinctive He-Ne-Ar solubility patterns are associated with the different ring structure topologies. Combined, these observations suggest ring structures have a strong influence on noble gas solubility in materials and could facilitate the recycling of noble gases, along with other volatiles (i.e., water, chlorine, and fluorine), into the mantle. Measurements of Ne and Ar solubility in antigorite, however, are highly variable and correlated with each other, suggesting multiple factors contribute the solubility of noble gases in serpentine-rich materials.

  16. 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.

  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. Comparison of Life Cycle Greenhouse Gases from Natural Gas Pathways for Medium and Heavy-Duty Vehicles.

    PubMed

    Tong, Fan; Jaramillo, Paulina; Azevedo, Inês M L

    2015-06-16

    The low-cost and abundant supply of shale gas in the United States has increased the interest in using natural gas for transportation. We compare the life cycle greenhouse gas (GHG) emissions from different natural gas pathways for medium and heavy-duty vehicles (MHDVs). For Class 8 tractor-trailers and refuse trucks, none of the natural gas pathways provide emissions reductions per unit of freight-distance moved compared to diesel trucks. When compared to the petroleum-based fuels currently used in these vehicles, CNG and centrally produced LNG increase emissions by 0-3% and 2-13%, respectively, for Class 8 trucks. Battery electric vehicles (BEVs) powered with natural gas-produced electricity are the only fuel-technology combination that achieves emission reductions for Class 8 transit buses (31% reduction compared to the petroleum-fueled vehicles). For non-Class 8 trucks (pick-up trucks, parcel delivery trucks, and box trucks), BEVs reduce emissions significantly (31-40%) compared to their diesel or gasoline counterparts. CNG and propane achieve relatively smaller emissions reductions (0-6% and 19%, respectively, compared to the petroleum-based fuels), while other natural gas pathways increase emissions for non-Class 8 MHDVs. While using natural gas to fuel electric vehicles could achieve large emission reductions for medium-duty trucks, the results suggest there are no great opportunities to achieve large emission reductions for Class 8 trucks through natural gas pathways with current technologies. There are strategies to reduce the carbon footprint of using natural gas for MHDVs, ranging from increasing vehicle fuel efficiency, reducing life cycle methane leakage rate, to achieving the same payloads and cargo volumes as conventional diesel trucks. PMID:25938939

  19. Noble gas evidence for two fluids in the Baca (Valles Caldera) geothermal reservoir

    NASA Astrophysics Data System (ADS)

    Smith, S. P.; Kennedy, B. M.

    1985-04-01

    Noble gas elemental and isotopic abundances were measured in steam from four wells in the Baca geothermal reservoir located in the Valles Caldera, New Mexico. The 40Ar /36Ar ratio and noble gas elemental abundances relative to 36Ar are all strongly correlated with 1/ 36Ar, the inverse of the argon content. Ratios of ( ?, n)-produced 21Ne? and radiogenic 40Ar? to total 4He (dominantly radiogenic) are nearly constant at 2.1 × 10-8 and 0.20, respectively. The 3He /4He ratio covers a restricted range of 3.9 to 4.8 times atmospheric. The high 3He content of the gas indicates the presence of a helium component ultimately derived from the mantle. Kr and Xe isotopic compositions are close to atmospheric; excess 129Xe? is <0.25% of the total 129Xe. The high degree of linear correlation among the various noble gas results strongly suggests that the Baca reservoir contains two distinct fluids that are produced in varying proportions from individual wells. The noble gases in fluid A (~2900 mg/1 C1) are air-like, but with lighter gases and isotopes preferentially enriched. The fluid A 36Ar content is low, only 13% that of 10°C air-saturated water (ASW). The second fluid, B (~ 1700 mg/1 C1), is the dominant carrier of the radiogenic and mantle-derived gases. The heavier non-radiogenic gases are preferentially enriched in fluid B, and its 36Ar content is very low, only 5-7% ASW. The source of the noble gases in fluid A is tentatively ascribed to leaching of the relatively young (<1.4 m.y.) volcanic Bandelier Tuff. The radiogenic gases and mantle-derived helium in fluid B suggest a deeper source, possibly including gases escaping from a magma.

  20. Towards a Noble Gas Oscillator

    NASA Astrophysics Data System (ADS)

    Korver, Anna; Walker, Thad

    2014-05-01

    Noble gas NMR detected by alkali co-magnetometers has the potential for measurement of precession frequencies at the pHz level. This is done by eliminating the dominant known sources of systematic errors: alkali frequency shifts and quadrupole shifts. We present results of successful synchronous pumping of noble gas nuclei and measurements of alkali co-magnetometer sensitivity levels that project a 131-Xe noise level of 100 nHz /?{ Hz} . Future dual noble-gas co-magnetometry promises to improve the noise level by a factor of 10 or more. This research is supported by the NSF and Northrop-Grumman Corp.

  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. Noble gas impurity balance and exhaust model for DIII-D and JET 1 Research sponsored in part by the US Department of Energy, under contract number DE-AC05-96OR22464 with Lockheed Martin Energy Research Corporation. 1

    Microsoft Academic Search

    D. L. Hillis; J. Hogan; M. von Hellermann; J. Ehrenberg; L. Horton; R. König; P. Morgan; G. Saibene; M. R. Wade

    1999-01-01

    Experiments to study the exhaust of noble gases (helium and 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

  3. 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

  4. Calibration of HPGe gamma-ray detectors for measurement of radioactive noble gas sources

    Microsoft Academic Search

    L. Pibida; S. S. Nafee; M. Unterweger; M. M. Hammond; L. Karam; M. I. Abbas

    2007-01-01

    Measurements of radioactive noble gases are routinely made with gamma-ray spectrometers. This work describes the calibration of high purity germanium detectors provided by the full-energy-peak efficiency as a function of the gamma-ray energy. A comparison of measured efficiency values with a new, simplified method based on a direct mathematical method is given here.

  5. Noble gas tracing of groundwater\\/coalbed methane interaction in the San Juan Basin, USA

    Microsoft Academic Search

    Zheng Zhou; Chris J. Ballentine; Rolf Kipfer; Martin Schoell; Steve Thibodeaux

    2005-01-01

    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 CO2 sequestration potential of coalbed systems. We show here how noble gases can be used to construct a physical model that

  6. Noble gas compositions of Antarctic micrometeorites collected at the Dome Fuji Station in 1996 and 1997

    Microsoft Academic Search

    Takahito Osawa; Keisuke Nagao

    2002-01-01

    The noble gases He, Ne, Ar, Kr, and Xe were measured in 27 individual Antarctic micrometeorites (AMMs) in the size range 60 to 250 mum that were collected at the Dome Fuji Station. Eleven of the AMMs were collected in 1996 (F96 series) and sixteen were collected in 1997 (F97 series). One of the F97 AMMs is a totally melted

  7. Experimental study for noble gas release and exchange under high-speed frictional melting

    Microsoft Academic Search

    Keiko Sato; Hidenori Kumagai; Takehiro Hirose; Hajimu Tamura; Kazuo Mizoguchi; Toshihiko Shimamoto

    2009-01-01

    Isotope ratios of noble gases in certain minerals are believed to be modified easily by their ambient reservoirs when the minerals reach temperatures that are higher than their closure temperatures. The thermal history of a rock or a geologic event, even a fault movement, can therefore be determined quantitatively by application of radiometric dating methods to different minerals. However, neither

  8. 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.

  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. 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.

  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. Non-atmospheric noble gases from CO2 well GA

    Microsoft Academic Search

    M. W. Caffee; G. B. Hudson; C. Velsko; E. C. Alexander Jr.; G. R. Huss; A. R. Chivas

    1988-01-01

    In recent years a number of studies of both terrestrial and extraterrestrial material has allowed the piecing together of a picture of events occurring in the early solar system (4.5 Gyr ago), including the formation of the earth. However, before this picture can be completed with an appropriate amount of detail it will be necessary to make further advances. One

  13. 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…

  14. Tectonic implications of radiogenic noble gases in planetary atmospheres

    SciTech Connect

    Turcotte, D.L.; Schubert, G.

    1988-04-01

    An account is given of the ways in which the He-4 and Ar-40 radiogenic isotopes furnish important constraints on planetary interior tectonics. In the case of the earth, where there are such independent constraints on radiogenic isotope concentrations as observed surface heat flow, the specification of radiogenic isotope concentration allows the interpretation of data on the Ar-40 atmospheric mass and mantle He-4 in terms of models for the entire mantle and of layered mantle convection. He loss rate estimates through the Venus atmosphere indicate a flux that is nearly equal to that through the earth atmosphere. 34 references.

  15. Excitation of the metastable states of the noble gases

    SciTech Connect

    Srivastava, Rajesh; Sharma, Lalita [Department of Physics, Indian Institute of Technology-Roorkee, Roorkee 247667 (India); Stauffer, A. D. [Department of Physics and Astronomy, York University, Toronto, Ontario, M3J 1P3 (Canada)

    2006-07-15

    We have used the relativistic distorted-wave approximation to calculate the excitation of the lowest metastable states of neon, argon, krypton, and xenon [the J=0,2 levels of the np{sup 5}(n+1)s configuration] to the ten higher-lying fine-structure levels of the np{sup 5}(n+1)p configuration. We compare our results with experimental measurements of the integrated cross section at energies up to 400 eV and with other theoretical calculations for these cross sections.

  16. Noble-gas evidence for geothermal activity in a karstic terrain: Rocky Mountains, Canada.

    NASA Astrophysics Data System (ADS)

    Mazor, Emanuel; van Everdingen, Robert O.; Krouse, H. Roy

    1983-06-01

    Geothermally heated fluids are identified as a component in warm (up to 54°C) springs in the southern Canadian Rocky Mountains. High concentrations of radiogenic He (10 -3 ccSTP/cc gas) and atmospheric Ne, Ar, Kr and Xe in the gases that vigorously bubble at the Fairmont Hot Spring, assign the latter to be a "drowned" fumarole, fed by geothermal steam. Up to 75% depletions in the atmospheric noble gases in several warm springs indicate contributions of residual geothermal water. On the other hand, in a few cases noble gases were found in excess ( W) over the expected concentrations in airequilibrated recharge water. The observed "reversed" pattern of wnc > WAr > Wkr > Wxe is interpreted as excess air, incorporated during recharge through karstic conduits. The mixing ratios of geothermal and karstic waters can be deduced.

  17. Effect of the Fractional Composition of a Fine-Grained Adsorbent on the Efficiency with Which Furnace Gases are Cleaned of Heavy Metals

    Microsoft Academic Search

    G. V. Kashakashvili; B. G. Gogichaishvili; O. Sh. Mikadze; G. G. Tsnoriashvili; G. A. Lomtatidze; Z. S. Svanidze; A. N. Gagnidze

    2004-01-01

    Air contains a large number of substances of natural and anthropogenic origins, and both the qualitative and quantitative composition of air is continually changing. Among the substances in air are water vapor, dust, and various chemicals present in the form of gases, vapors, and aerosols. The dispersed phase in an aerosol can be a solid or a liquid. The sizes

  18. 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).

  19. Lithium [Li*(2 2P1\\/2,3\\/2)] fine structure transitions induced by collisions with noble gas atoms

    Microsoft Academic Search

    Julianne Elward-Berry; Michael J. Berry

    1980-01-01

    Dye laser excitation and interferometric fluorescence analysis techniques were used to determine collision induced fine structure transition rate coefficients in the Li*(2 2PJ)+ He, Ne, Ar, Kr, and Xe systems at a temperature of 555.7 K. All the noble gases induce transitions at ''gas kinetic'' rates, but differences in the individual magnitudes of the rate coefficients are probably sensitive to

  20. Noble metal additive modulation of gas sensitivity of BaSnO 3, explained by a work function based model

    Microsoft Academic Search

    C. V. Gopal Reddy; S. V. Manorama; V. J. Rao; Arun Lobo; S. K. Kulkarni

    1999-01-01

    Barium stannate, a semiconducting oxide with cubic perovskite structure, has been prepared by the thermal decomposition method. Of its several applications, this material has proved to be one of the successful candidates for chemical sensors to detect toxic and inflammable gases. BaSnO3 was incorporated with different noble metal additives and the gas sensing behavior of these materials to various reducing

  1. NEST: Noble Element Simulation Technique

    NASA Astrophysics Data System (ADS)

    Szydagis, M.; Barry, N.; Kazkaz, K.; Mock, J.; Stolp, D.; Sweany, M.; Tripathi, M.; Uvarov, S.; Walsh, N.; Woods, M.

    2013-07-01

    NEST (Noble Element Simulation Technique) offers comprehensive, accurate, and precise simulation of the excitation, ionization, and corresponding scintillation and electroluminescence processes in liquid noble elements, useful for direct dark matter detectors, double beta decay searches, PET scans, and general radiation detection technology. Written in C++, NEST is an add-on module for the Geant4 simulation package that incorporates more detailed physics than is currently available into the simulation of scintillation. NEST is of particular use for low-energy nuclear recoils. All available liquid xenon data on nuclear recoils and electron recoils to date have been taken into consideration in arriving at the current models. NEST also handles the magnitude of the light and charge yields of nuclear recoils, including their electric field dependence, thereby shedding light on the possibility of detection or exclusion of a low-mass dark matter WIMP by liquid xenon detectors.

  2. Significant Interactions between Uranium and Noble-Gas Atoms: Coordination of the UO2+ Cation by Ne, Ar, Kr, and Xe Atoms

    Microsoft Academic Search

    Xuefeng Wang; Lester Andrews; Jun Li; Bruce E. Bursten

    2004-01-01

    Laser-ablated uranium cation reacts with O2 to give UO2+, which is found to form UO2+(Ng)n (Ng = Ne, Ar, Kr, Xe) complexes on condensation with excess noble gas. Experiments with mixtures of noble gases lead to five new absorptions for the mixed UO2+(Ng)x(Ng')y complexes and show that the coordination number is five for Ng = Ar, Kr, and Xe. These

  3. Computational investigation of noble gas adsorption and separation by nanoporous materials.

    SciTech Connect

    Allendorf, Mark D. (Sandia National Laboratories, Livermore, CA); Sanders, Joseph C.; Greathouse, Jeffery A.

    2008-10-01

    Molecular simulations are used to assess the ability of metal-organic framework (MOF) materials to store and separate noble gases. Specifically, grand canonical Monte Carlo simulation techniques are used to predict noble gas adsorption isotherms at room temperature. Experimental trends of noble gas inflation curves of a Zn-based material (IRMOF-1) are matched by the simulation results. The simulations also predict that IRMOF-1 selectively adsorbs Xe atoms in Xe/Kr and Xe/Ar mixtures at total feed gas pressures of 1 bar (14.7 psia) and 10 bar (147 psia). Finally, simulations of a copper-based MOF (Cu-BTC) predict this material's ability to selectively adsorb Xe and Kr atoms when present in trace amounts in atmospheric air samples. These preliminary results suggest that Cu-BTC may be an ideal candidate for the pre-concentration of noble gases from air samples. Additional simulations and experiments are needed to determine the saturation limit of Cu-BTC for xenon, and whether any krypton atoms would remain in the Cu-BTC pores upon saturation.

  4. 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

  5. Development of hyperpolarized noble gas MRI

    NASA Astrophysics Data System (ADS)

    Albert, M. S.; Balamore, D.

    1998-02-01

    Magnetic resonance imaging using the MR signal from hyperpolarized noble gases 129Xe and 3He may become an important new diagnostic technique. Alex Pines (adapting the hyperpolarization technique pioneered by William Happer) presented MR spectroscopy studies using hyperpolarized 129Xe. The current authors recognized that the enormous enhancement in the detectability of 129Xe, promised by hyperpolarization, would solve the daunting SNR problems impeding their attempts to use 129Xe as an in vivo MR probe, especially in order to study the action of general anesthetics. It was hoped that hyperpolarized 129Xe MRI would yield resolutions equivalent to that achievable with conventional 1H 2O MRI, and that xenon's solubility in lipids would facilitate investigations of lipid-rich tissues that had as yet been hard to image. The publication of hyperpolarized 129Xe images of excised mouse lungs heralded the emergence of hyperpolarized noble-gas MRI. Using hyperpolarized 3He, researchers have obtained images of the lung gas space of guinea pigs and of humans. Lung gas images from patients with pulmonary disease have recently been reported. 3He is easier to hyperpolarize than 129Xe, and it yields a stronger MR signal, but its extremely low solubility in blood precludes its use for the imaging of tissue. Xenon, however, readily dissolves in blood, and the T1 of dissolved 129Xe is long enough for sufficient polarization to be carried by the circulation to distal tissues. Hyperpolarized 129Xe dissolved-phase tissue spectra from the thorax and head of rodents and humans have been obtained, as have chemical shift 129Xe images from the head of rats. Lung gas 129Xe images of rodents, and more recently of humans, have been reported. Hyperpolarized 129Xe MRI (HypX-MRI) may elucidate the link between the structure of the lung and its function. The technique may also be useful in identifying ventilation-perfusion mismatch in patients with pulmonary embolism, in staging and tracking the success of therapeutic approaches in patients with chronic obstructive airway diseases, and in identifying candidates for lung transplantation or reduction surgery. The high lipophilicity of xenon may allow MR investigations of the integrity and function of excitable lipid membranes. Eventually, HypX-MRI may permit better imaging of the lipid-rich structures of the brain. Cortical brain function is one perfusion-dependent phenomena that may be explored with hyperpolarized 129Xe MR. This leads to the exciting possibility of conducting hyperpolarized 129Xe functional MRI (HypX-fMRI) studies.

  6. Significant Interactions between Uranium and Noble-Gas Atoms: Coordination of the UO2+ Cation by Ne, Ar, Kr, and Xe Atoms

    SciTech Connect

    Wang, Xuefeng; Andrews, Lester; Li, Jun; Bursten, Bruce E.

    2004-05-03

    Laser-ablated uranium cation reacts with O2 to give UO2+, which is found to form UO2+(Ng)n (Ng = Ne, Ar, Kr, Xe) complexes on condensation with excess noble gas. Experiments with mixtures of noble gases lead to five new absorptions for the mixed UO2+(Ng)x(Ng')y complexes and show that the coordination number is five for Ng = Ar, Kr, and Xe. These results are consistent with predictions by relativistic density functional calculations and indicate significant bonding between U and noble-gas atoms.

  7. Noble gas anomalies related to high-intensity methane gas seeps in the Black Sea

    Microsoft Academic Search

    C. P. Holzner; D. F. McGinnis; C. J. Schubert; R. Kipfer; D. M. Imboden

    2008-01-01

    Dissolved noble gases and tritium were analyzed at a series of high-intensity methane gas seeps in the Black Sea to study the transport and gas exchange induced by bubble-streams in the water column. These processes affect marine methane emissions to the atmosphere and are therefore relevant to climate warming. The seep areas investigated are located in the Dnepr paleo-delta, west

  8. Multicollector High Precision Resolution of Primordial Kr and Xe in Mantle CO2 Well Gases

    NASA Astrophysics Data System (ADS)

    Holland, G.; Ballentine, C.; Cassidy, M.

    2008-12-01

    Noble gas isotopes in magmatic CO2 well gases provide a unique insight into mantle volatile origin and dynamics [1-3]. Previous work has resolved mantle 20Ne/22Ne ratios consistent with a solar wind irradiated meteoritic source for mantle He and Ne [1]. This is distinct from Solar Wind values that might be expected if the primary mechanism of terrestrial mantle volatile acquisition was through the gravitational capture of solar nebula gases [see 4]. Within the CO2 well gases a primordial component has also been resolved in the non- radiogenic Xe isotopic composition [2,3]. Using multicollector mass spectrometry we have observed a 124Xe/130Xe excess of 1.85 percent over air plus/minus 0.17 percent for the least air contaminated samples. At this level of precision we are for the first time able to differentiate between a trapped meteoritic origin (average carbonaceous chondrite or Q Xe) rather than Solar Wind origin as the primordial Xe component. The well gases also contain Kr which, in the least air contaminated sample, have a correlated 86Kr/82Kr excess of 0.55 percent over air plus/minus 0.04 percent. Whilst mass dependent fractionation can theoretically produce correlated excesses in 124Xe-128Xe and 82Kr-86Kr isotopes, no fractionation from air is observed in 38Ar/36Ar [3] and the Kr excesses are in the opposite sense to that of Xe. From 136Xe excesses, Kr fission yield from Pu and U can be calculated and subtracted from the Kr isotopic signature. This fission-corrected signature is most reasonably explained as a primordial component. This is the first time that primordial Kr has ever been resolved in a terrestrial sample. The primordial Kr isotopic signature is distinct from Solar Wind Kr and is consistent with the primordial Kr also originating as a trapped component within meteorites. We are now able to demonstrate that both the light (He and Ne) and Heavy (Kr and Xe) noble gas origin in the terrestrial mantle is consistent with a trapped component during the accretionary process and can discount gravitational capture as the principle mechanism of interior planetary volatile acquisition. References: [1] Ballentine, C.J. et al., Nature, 433. 33-38, (2005) [2] Caffee, M.W. et al., Science, 285, 2115- 2118, (1999) [3] Holland G. and Ballentine C. J., Nature, 441, 186-191 (2006) [4] Pepin R.O. and Porcelli D. Rev. Min. Geochem. 47, 191-246 (2002)

  9. Quantum Number Dependence of Lineshift Coefficients Induced by Collisions with Noble Gas Perturbers in the nu(3) Band of NO(2).

    PubMed

    Sumpf; Bouazza; Kissel; Kronfeldt

    2000-02-01

    To complete our study concerning lineshift in the rovibrational spectrum of (14)N(16)O(2), a pulse-driven three-channel lead salt diode laser spectrometer was applied to record high-resolution spectra at room temperature in the 6.2-µm region corresponding to the nu(3) band at low NO(2) concentrations. The shift was studied for collisions with the noble gases He, Ne, Ar, Kr, and Xe. This paper extends our recently published data in order to analyze the quantum number dependence of the shift effect more precisely. Therefore, in this paper, additionally eight unresolved NO(2) doublets covering an enlarged quantum number range (10 noble gas) and additionally broadening coefficients gamma(NO(2)-noble gas) were determined. Hereby, the experimental data confirm general trends published recently. In this study, in the case of broadening for the lighter rare gases helium, neon, and argon, only a slight decrease of gamma(NO(2)-noble gas) was observed, whereas for the rare gases with a higher atomic weight, i.e., krypton and xenon, a pronounced decrease of gamma(NO(2)-noble gas) with increasing rotational quantum number N(") occurred. All measured lineshift coefficients were negative. The absolute value of the determined lineshift coefficient ||delta(NO(2)-noble gas) || increases with the mass of the noble gas perturber, i.e., ||delta(NO(2)-He) || < ||delta(NO(2)-Ne) || < ||delta(NO(2)-Ar) || < ||delta(NO(2)-Kr) || < ||delta(NO(2)-Xe) ||. Within the studied quantum number range, an increase ||delta(NO(2)-noble gas) || with increase of N(") was observed. A typical trend of the shift and broadening data on the quantum number K(")(a) was not observed. Copyright 2000 Academic Press. PMID:10637106

  10. 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.

  11. 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.

  12. 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.

  13. Qingguo Zhang David R. Noble

    E-print Network

    Lieuwen, Timothy C.

    in utilizing coal-derived syngas or fuels from other sources, such as biomass, landfill gas, or process gas: 10.1115/1.2718566 Keywords: syngas, lean blowout, hydrogen Introduction This paper describes, such as liquids or synthetic gases derived from other organic sources, e.g., coal, sewage gas, biomass

  14. ABOUT THE POSSIBLE ROLE OF HYDROCARBON LAKES IN THE ORIGIN OF TITAN'S NOBLE GAS ATMOSPHERIC DEPLETION

    SciTech Connect

    Cordier, D. [Ecole Nationale Superieure de Chimie de Rennes, CNRS, UMR 6226, Avenue du General Leclerc, CS 50837, 35708 Rennes Cedex 7 (France); Mousis, O. [Universite de Franche-Comte, Institut UTINAM, CNRS/INSU, UMR 6213, 25030 Besancon Cedex (France); Lunine, J. I. [Dipartimento di Fisica, Universita degli Studi di Roma 'Tor Vergata', Rome (Italy); Lebonnois, S. [Laboratoire de Meteorologie Dynamique, Jussieu, P.O. Box 99, 75252 PARIS cedex 05 (France); Lavvas, P. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ (United States); Lobo, L. Q.; Ferreira, A. G. M., E-mail: daniel.cordier@ensc-rennes.f [Departamento de Engenharia Quimica, Universidade de Coimbra, Coimbra 3030-290 (Portugal)

    2010-10-01

    An unexpected feature of Titan's atmosphere is the strong depletion in primordial noble gases revealed by the Gas Chromatograph Mass Spectrometer aboard the Huygens probe during its descent on 2005 January 14. Although several plausible explanations have already been formulated, no definitive response to this issue has yet been found. Here, we investigate the possible sequestration of these noble gases in the liquid contained in lakes and wet terrains on Titan and the consequences for their atmospheric abundances. Considering the atmosphere and the liquid existing on the soil as a whole system, we compute the abundance of each noble gas relative to nitrogen. To do so, we make the assumption of thermodynamic equilibrium between the liquid and the atmosphere, the abundances of the different constituents being determined via regular solution theory. We find that xenon's atmospheric depletion can be explained by its dissolution at ambient temperature in the liquid presumably present on Titan's soil. In the cases of argon and krypton, we find that the fractions incorporated in the liquid are negligible, implying that an alternative mechanism must be invoked to explain their atmospheric depletion.

  15. 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.

  16. On a cryogenic noble gas ion catcher

    E-print Network

    P. Dendooven; S. Purushothaman; K. Gloos

    2005-12-20

    In-situ purification of the gas used as stopping medium in a noble gas ion catcher by operating the device at low temperatures of 60 to 150 K was investigated. Alpha-decay recoil ions from a 223Ra source served as energetic probes. The combined ion survival and transport efficiencies for 219Rn ions saturated below about 90 K, reaching 28.7(17) % in helium, 22.1(13) % in neon, and 17.0(10) % in argon. These values may well reflect the charge exchange and stripping cross sections during the slowing down of the ions, and thus represent a fundamental upper limit for the efficiency of noble gas ion catcher devices. We suggest the cryogenic noble gas ion catcher as a technically simpler alternative to the ultra-high purity noble gas ion catcher operating at room temperature.

  17. Radon and helium in soil gases in the Phlegraean Fields, central Italy

    NASA Astrophysics Data System (ADS)

    Lombardi, S.; Reimer, G. M.

    1990-05-01

    The distribution and migration of radon and soil-gas concentrations in the Phlegraean Fields, Italy, are controlled by the tectonic features of the area. Radon is supplied from surficial sources and helium has both surficial and deep origins. There is no direct correlation between the two noble gases on a point-to-point basis but the areal distribution of both gases is similar, suggesting that the distribution is controlled primarily by fractures and movement of geothermal fluids.

  18. New instrumental method for determining noble fission gas retained in irradiated nuclear fuels

    SciTech Connect

    Baldwin, D L

    1981-01-01

    The measurement of fission products generated in nuclear fuel is necessary for the complete characterization of the irradiated fuel. The gaseous fission products, xenon and krypton, are of particular importance. A new method has been developed for the measurement of the fission gas retained in nuclear fuel. The method involves extraction of xenon and krypton by melting the fuel in a commercially available furnace. Several factors influence the complete fusion of the fuel and release of the noble gases. Development work aimed at identifying and understanding these factors is discussed. The gases are purified after release from the fuel and collected on cryogenically-cooled activated charcoal. The gases are subsequently released from the charcoal trap and measured by gas chromatography. Column requirements and optimum operating conditions are discussed. Various modifications to the furnace are necessary for reliable performance within the high radiation environment. Other radiological problems are identified and their solutions discussed.

  19. Studies of a Dual Noble Gas Maser

    Microsoft Academic Search

    R. E. Stoner; D. Bear; E. R. Oteiza; R. L. Walsworth; M. A. Rosenberry; T. E. Chupp

    1996-01-01

    The dual noble gas maser (DNGM) supports the simultaneous, active maser oscillation of co-habitating ensembles of ^129Xe and ^3He gas operating on their nuclear spin-1\\/2 Zeeman transitions. Population inversions for the ^129Xe and ^3He masers are created by spin-exchange collisions between the noble gas atoms and laser-optically-pumped rubidium vapor. We will describe ongoing development of a second-generation DNGM at the

  20. 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.

  1. Collisional radiative recombination in high-pressure noble gas mixtures

    NASA Technical Reports Server (NTRS)

    Whitten, B. L.; Downes, L. W.; Wells, W. E.

    1981-01-01

    Rate coefficients are calculated for neutral-assisted collisional radiative recombination in dense, weakly ionized rare-gas mixtures using the quasiequilibrium model developed by Bates. It is shown that the recombination rate can be significantly altered by the presence of a buffer gas. In particular, the presence of helium can enhance the collisional radiative recombination rate coefficient of heavy rare gases by a factor of 5.

  2. Far-ultraviolet signatures of the 3He(n,tp) reaction in noble gas mixtures

    E-print Network

    Hughes, Patrick P; Thompson, Alan K; Vest, Robert E; Clark, Charles W

    2010-01-01

    Previous work showed that the 3He(n,tp) reaction in a cell of 3He at atmospheric pressure generated tens of far-ultraviolet photons per reacted neutron. Here we report amplification of that signal by factors of 1000 and more when noble gases are added to the cell. Calibrated filter-detector measurements show that this large signal is due to noble-gas excimer emissions, and that the nuclear reaction energy is converted to far-ultraviolet radiation with efficiencies of up to 30%. The results have been placed on an absolute scale through calibrations at the NIST SURF III synchrotron. They suggest possibilities for high-efficiency neutron detectors as an alternative to existing proportional counters.

  3. 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.

  4. Van der Waals molecules and collision pairs of noble-gas atoms ahead of a shock wave front

    Microsoft Academic Search

    J. G. Eden; V. S. Zuev

    1997-01-01

    The effect of creation of an excess concentration of free electrons in an anomalously thick layer (?5 cm) ahead of an explosively\\u000a driven shock wave in noble gases is discussed and interpreted. This effect is the ionization of excited 1u-state molecules produced due to the absorption of a small intensity flux (as compared to the ionization one) of photons (with

  5. Noble Gas Induced Pressure Broadening in the ? 3, ? 2+ ? 3? ? 2, and 2? 2Bands of NO 2

    Microsoft Academic Search

    B. Sumpf; V. V. Pustogov; H.-D. Kronfeldt

    1996-01-01

    Experimental results on the pressure broadening of NO2for collisions with the noble gases He, Ne, Ar, Kr, and Xe are presented. The broadening coefficients of six lines in the ?3band near 1616.85 cm?1with quantum numbers 2 ?N? ? 44, 1 ?K?a? 5, and of seven lines in the ?2+ ?3? ?2band with 29 ?N? ? 36, 0 ?K?a? 5, and

  6. Quantum Number Dependence of Lineshift Coefficients Induced by Collisions with Noble Gas Perturbers in the ? 3 Band of NO 2

    Microsoft Academic Search

    B. Sumpf; S. Bouazza; A. Kissel; H.-D. Kronfeldt

    2000-01-01

    To complete our study concerning lineshift in the rovibrational spectrum of 14N16O2, a pulse-driven three-channel lead salt diode laser spectrometer was applied to record high-resolution spectra at room temperature in the 6.2-?m region corresponding to the ?3 band at low NO2 concentrations. The shift was studied for collisions with the noble gases He, Ne, Ar, Kr, and Xe. This paper

  7. 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.

  8. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble...FDA's “Class II Special Controls Guidance Document: Dental Noble Metal Alloys.” The devices are exempt...

  9. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble...FDA's “Class II Special Controls Guidance Document: Dental Noble Metal Alloys.” The devices are exempt...

  10. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble...FDA's “Class II Special Controls Guidance Document: Dental Noble Metal Alloys.” The devices are exempt...

  11. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble...FDA's “Class II Special Controls Guidance Document: Dental Noble Metal Alloys.” The devices are exempt...

  12. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble...FDA's “Class II Special Controls Guidance Document: Dental Noble Metal Alloys.” The devices are exempt...

  13. Roosevelt County 027 - A low-shock ureilite with interstitial silicates and high noble gas concentrations

    NASA Technical Reports Server (NTRS)

    Goodrich, Cyrena Anne; Keil, Klaus; Berkley, John L.; Laul, J. C.; Smith, M. R.

    1987-01-01

    The RC027 lightly-shocked ureilite contains less than 1 percent of a fine-grained interstitial silicate that has an igneous texture indicating crystallization from an interstitial liquid. RC027 is also noted to exhibit the strongest olivine preferred-orientation thus far observed in a ureilite; its fabric is characteristic of fabrics formed by tabular minerals in a fluid laminar flow regime, and is unlike those formed by synectonic recrystallization and plastic flow. The elemental and isotopic compositions of noble gases in RC027 are typical of previously analyzed ureilites.

  14. 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.

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

    E-print Network

    Capolupo, Antonio; Illuminati, Fabrizio

    2013-01-01

    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.

  17. 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

  18. Resonance in scattering and absorption from large noble gas clusters

    E-print Network

    Ditmire, Todd

    .gov Abstract: Light scattering in large noble gas clusters irradiated by intense laser pulses was studiedResonance in scattering and absorption from large noble gas clusters J. Zweiback, T.Ditmire and M of noble-gas cluster explosions," Phys. Rev. A 59, R3166­R3169 (1999). 8. L. K¨oller, M. Schumacher, J. K

  19. Noble gas-halogen transfer laser method and means

    Microsoft Academic Search

    R. M. Hill; D. L. Huestis; D. C. Lorents; M. V. Mccusker

    1981-01-01

    A halogen transfer laser method and means are disclosed employing a dilute mixture of molecular halogen vapor in high pressure noble gas. Noble gas atoms and molecules are excited by use of electrons to high energy metastable and\\/or excimer states. Collisional and\\/or radiative transfer of electronic excitation from the excited noble gas atoms and molecules to the lasing halogen molecules

  20. Nuclear Magnetic Resonance Experiments using Laser-Polarized Noble Gas

    E-print Network

    Walsworth, Ronald L.

    Nuclear Magnetic Resonance Experiments using Laser-Polarized Noble Gas A thesis presented by Glenn Gas Abstract Three different nuclear magnetic resonance (NMR) experiments using laser- polarized noble.e., the probability that a spin has not changed sign up to time t) in the diffusion of laser-polarized noble gas

  1. A Grounded Theory of the Development of Noble Youth Purpose

    ERIC Educational Resources Information Center

    Bronk, Kendall Cotton

    2012-01-01

    Having a noble purpose in life is an important component of positive youth development; however, little is known about how noble purposes develop over time. Therefore, using three waves of interviews over a 5-year period with 9 adolescents (N = 9) who demonstrated intense commitments to various noble purposes, the present study developed a…

  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. 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.

  4. Stochastic ionization through noble tori: Renormalization results

    E-print Network

    C. Chandre; T. Uzer

    2002-03-29

    We find that chaos in the stochastic ionization problem develops through the break-up of a sequence of noble tori. In addition to being very accurate, our method of choice, the renormalization map, is ideally suited for analyzing properties at criticality. Our computations of chaos thresholds agree closely with the widely used empirical Chirikov criterion.

  5. 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)

  6. 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…

  7. Separation of polar gases from nonpolar gases

    DOEpatents

    Kulprathipanja, S.

    1986-08-19

    The separation of polar gases from nonpolar gases may be effected by passing a mixture of nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The porous support is pretreated prior to casting of the mixture thereon by contact with a polyhydric alcohol whereby the pores of the support are altered, thus adding to the increased permeability of the polar gas.

  8. An Alteration Scale for CM Chondrites and Implications for Planetary Noble Gas Abundances

    NASA Astrophysics Data System (ADS)

    Browning, L. B.; McSween, H. Y., Jr.; Zolensky, M.

    1993-07-01

    Three progressive alteration parameters have been identified from the mineralogical and textural analyses of 7 CM chondritic falls. These indices predict the following order of progressive alteration [3]: Murchison (MC)noble gases, Ar^36, Xe^84, and Kr^132. Two of the progressive alteration parameters monitor the volumetric production of CM phyllosilicates, which was estimated from the modal analysis of 1 to 3 thin sections from each of the analyzed falls. These are the percentages of phyllosilicates in chondrules and the volume of anhydrous matrix silicates, which increase and decease, respectively, with progressive alteration. The third alteration index, the mean Fe^3+/(2-Si) ratio in phyllosilicates, is a stoichiometric-based approximation that monitors variations in mineral composition during progressive alteration, and decreases with increasing alteration. Values of Fe^3+/(2-Si) were calculated from an average of microprobe analyses of matrix phyllosilicates in each meteorite based on a generalized phyllosilicate stoichiometry, [(Fe, Mg)(sub)3-x (Al,Fe^3+)(sub)x(Si(sub)(2-x)(Al,Fe^3+)(sub)x)O(sub)5(OH)(sub)4], which accommodates a continuous transition from cronstedtite to serpentine compositions. The bulk Ar^36 content of the 7 investigated samples decreases with increasing alteration as predicted by the alteration parameters, which suggests the possibility of degassing events. The same trend is observed for Kr^84 and Xe^132. The loss of noble gases in CM chondritic meteorites has previously been noted [1,5], and may be related to the open-system behavior that is predicted for other volatile components in CM chondrites, such as C1 [4], water [3], and methane [2]. Although high-temperature minerals are depleted in noble gases relative to the low- temperature phases of CM chondrites, we observe decreasing noble gas abundances with increased volumes of low-temperature phases. This can be explained by a scenario similar to one proposed by Wood [7], in which all CM chondrites originally had high gas contents, and were subsequently degassed to varying degrees in response to aqueous alteration in a parent body setting. An alternate explanation is that the correlation between noble gas content and the degree of alteration is the fortuitous result of primary trapped gas abundances. If, however, degassing did occur in response to progressive alteration, then the sequence of alteration reactions in CM chondrites may provide additional constraints on the retention sites for trapped noble gases. References: [1] Bogard D. D. et al. (1971) JGR, 76, 4076-4083. [2] Bourcier W. L. et al. (1992) LPS XXIII, 143-144.[3] Browning L. B. et al. (1993) LPS XXIV. [4] Bunch T. E. and Chang S. (1980) GCA, 44, 1543-1577. [5] Mazor E. et al. (1970) GCA, 34, 781-824. [6] Schultz L. and Kruse H. (1989) Meteoritics, 24, 155-172. [6] Wood J. A. (1967) Icarus, 6, 1-49. Fig. 1, which appears here in the hard copy shows how averaged ^36Ar contents [6] for individual CM chondrites decrease with increasing alteration, as indicated by the mean composition of phyllosilicates.

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

    NASA Astrophysics Data System (ADS)

    Burgess, Raymond; Turner, Grenville

    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.

  10. 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.

  11. Lithium (Li* (2 /sup 2/P/sub 1/2,3/2/)) fine structure transitions induced by collisions with noble gas atoms

    SciTech Connect

    Elward-Berry, J.; Berry, M.J.

    1980-04-15

    Dye laser excitation and interferometric fluorescence analysis techniques were used to determine collision induced fine structure transition rate coefficients in the Li* (2 /sup 2/P/sub J/)+ He, Ne, Ar, Kr, and Xe systems at a temperature of 555.7 K. All the noble gases induce transitions at ''gas kinetic'' rates, but differences in the individual magnitudes of the rate coefficients are probably sensitive to the long range portions of the Li* (2 /sup 2/P/sub J/) --noble gas interaction potentials. There is no appreciable isotope effect for /sup 6/Li*//sup 7/Li*+He, Ne, Ar systems. Simple models based upon localized transition concepts do not agree adequately with experimental results, suggesting that full dynamical computations using quantal and/or refined semiclassical formalisms are probably required for proper treatment of the Li* (2 /sup 2/P/sub J/) --noble gas systems and for stringent tests of various choices for the interaction potentials.

  12. Bonding of Multiple Noble-Gas Atoms to CUO in Solid Neon: CUO(Ng)(n) (Ng= Ar, Kr, Xe; n= 1, 2, 3, 4) Complexes and the Singlet-Triplet Crossover Point

    SciTech Connect

    Liang, Binyong; Andrews, Lester S.; Li, Jun; Bursten, Bruce E.

    2003-10-06

    Laser-ablated U atoms codeposited with CO in excess neon produce the novel CUO molecule, which forms distinct Ng complexes (Ng= Ar, Kr, Xe) with the heavier noble gases. The CUO(Ng) complexes are identified through CO isotopic and Ng reagent substitution and comparison to results of DFT frequency calculations.

  13. Spectral reshaping and pulse compression via sequential filamentation in gases.

    PubMed

    Vuong, Luat T; Lopez-Martens, Rodrigo B; Hauri, Christoph P; Gaeta, Alexander L

    2008-01-01

    We provide a theoretical description of the spatio-temporal dynamics of sequential filamentation in noble gases that can lead to pulse compression down to nearly single-cycle pulses. We show that the strong pulse compression occurs as a result of serially-generated on-axis filaments and spectral filtering of an extensive blue-shifted compressible spectra. We show that the dynamics of this sequential filamentation can be readily tuned by varying the gas pressure and can be scaled to various pulse energies. PMID:18521171

  14. 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.

  15. The Noble Element Simulation Technique (NEST)

    NASA Astrophysics Data System (ADS)

    Woods, Michael

    2013-04-01

    A comprehensive model for explaining the mean scintillation and electroluminescence yields in liquid and gaseous noble elements will be presented which informs an exhaustive simulation code called NEST (Noble Element Simulation Technique). All available liquid xenon data on electron and nuclear recoils have been incorporated, and significant progress has been made on extending NEST's applicability to argon. Results will be shown from Geant4 implementations for 1- and 2-phase xenon and argon detectors. The quasi-empirical NEST approach can lead to a better understanding of detector calibrations and performance verification and aid in the design and optimization of future detectors for dark matter or other applications, and assist in the data analysis stage of present detectors.

  16. 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

  17. Use of noble metals in hydrodeoxygenation reactions

    Microsoft Academic Search

    Aristóbulo Centeno; Rosanna Maggi; Bernard Delmon

    1999-01-01

    Two series of catalysts supported on active carbon containing noble metals (NM) Pt, Pd, Ru and Rh were prepared (bimetallic NM-Mo\\/C and trimetallic NM-CoMo\\/C catalysts) and tested in their sulphided form in hydrodeoxygenation (HDO) reactions of model molecules containing carbonyl, carboxyl, hydroxyl and methoxy groups. Results show that hydrogenation reactions of the carbonyl and carboxyl groups are favoured by the

  18. Noble gas mixture hollow cathode lasers

    Microsoft Academic Search

    M. Jánossy; L. Csillag; Z. Donkó; K. Rózsa

    1993-01-01

    A review of noble gas mixture ion lasers operating cw in hollow cathode discharges is given. The basic properties of hollow\\u000a cathode discharges and the main principles of tube construction are described. For the He?Kr, He?Ar and He?Ne?Xe systems laser\\u000a transitions, excitation mechanisms, operation of the lasers and questions of lasers for practical use are discussed. The single\\u000a frequency operation

  19. Complex oxide-noble metal conjugated nanoparticles.

    PubMed

    Guo, Jun-Ling; Chiou, Yao-De; Liang, Wen-I; Liu, Heng-Jui; Chen, Ying-Jiun; Kuo, Wei-Cheng; Tsai, Chih-Ya; Tsai, Kai-An; Kuo, Ho-Hung; Hsieh, Wen-Feng; Juang, Jenh-Yih; Hsu, Yung-Jung; Lin, Hong-Ji; Chen, Chien-Te; Liao, Xue-Pin; Shi, Bi; Chu, Ying-Hao

    2013-04-11

    Hybrid nanoparticles (NPs) composed of multiple components offer new opportunities for next-generation materials. In this study, a paradigm for the noble metal/ternary complex oxide hybrid NPs is reported by adopting pulsed laser ablation in liquids. As model hybrids, gold-spinel heterodimer (Au-CoFe2O4) and gold-pervoskite heterodimer (Au-SrTiO3) NPs are investigated. This work has demonstrated the diverse playgroup of NP conjugation enlarged by complex oxides. PMID:23427105

  20. Far-ultraviolet signatures of the {sup 3}He(n,tp) reaction in noble gas mixtures

    SciTech Connect

    Hughes, Patrick P.; Thompson, Alan K.; Vest, Robert E. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Coplan, Michael A. [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); Clark, Charles W. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); Joint Quantum Institute, National Institute of Standards and Technology and University of Maryland, Gaithersburg, Maryland 20899 (United States)

    2010-12-06

    Previous work showed that the {sup 3}He(n,tp) reaction in a cell of {sup 3}He at atmospheric pressure generated tens of far-ultraviolet photons per reacted neutron. Here we report amplification of that signal by factors of 1000 and more when noble gases are added to the cell. Calibrated filter-detector measurements show that this large signal is due to noble gas excimer emissions and that the nuclear reaction energy is converted to far-ultraviolet radiation with efficiencies of up to 30%. The results have been placed on an absolute scale through calibrations at the NIST SURF III synchrotron. They suggest possibilities for high-efficiency neutron detectors as an alternative to existing proportional counters.

  1. Noble gas and oxygen isotope studies of aubrites: A clue to origin and histories

    NASA Astrophysics Data System (ADS)

    Miura, Yayoi N.; Hidaka, Hiroshi; Nishiizumi, Kunihiko; Kusakabe, Minoru

    2007-01-01

    Noble gas measurements were performed for nine aubrites: Bishopville, Cumberland Falls, Mayo Belwa, Mount Egerton, Norton County, Peña Blanca Spring, Shallowater, ALHA 78113 and LAP 02233. These data clarify the origins and histories, particularly cosmic-ray exposure and regolith histories, of the aubrites and their parent body(ies). Accurate cosmic-ray exposure ages were obtained using the 81Kr-Kr method for three meteorites: 52 ± 3, 49 ± 10 and 117 ± 14 Ma for Bishopville, Cumberland Falls and Mayo Belwa, respectively. Mayo Belwa shows the longest cosmic-ray exposure age determined by the 81Kr-Kr method so far, close to the age of 121 Ma for Norton County. These are the longest ages among stony meteorites. Distribution of cosmic-ray exposure ages of aubrites implies 4-9 break-up events (except anomalous aubrites) on the parent body. Six aubrites show "exposure at the surface" on their parent body(ies): (i) neutron capture 36Ar, 80Kr, 82Kr and/or 128Xe probably produced on the respective parent body (Bishopville, Cumberland Falls, Mayo Belwa, Peña Blanca Spring, Shallowater and ALHA 78113); and/or (ii) chondritic trapped noble gases, which were likely released from chondritic inclusions preserved in the aubrite hosts (Cumberland Falls, Peña Blanca Spring and ALHA 78113). The concentrations of 128Xe from neutron capture on 127I vary among four measured specimens of Cumberland Falls (0.5-76 × 10 -14 cm 3STP/g), but are correlated with those of radiogenic 129Xe, implying that the concentrations of ( 128Xe) n and ( 129Xe) rad reflect variable abundances of iodine among specimens. The ratios of ( 128Xe) n/( 129Xe) rad obtained in this work are different for Mayo Belwa (0.045), Cumberland Falls (0.015) and Shallowater (0.001), meaning that neutron fluences, radiogenic 129Xe retention ages, or both, are different among these aubrites. Shallowater contains abundant trapped Ar, Kr and Xe (2.2 × 10 -7, 9.4 × 10 -10 and 2.8 × 10 -10 cm 3STP/g, respectively) as reported previously ( Busemann and Eugster, 2002). Isotopic compositions of Kr and Xe in Shallowater are consistent with those of Q (a primordial noble gas component trapped in chondrites). The Ar/Kr/Xe compositions are somewhat fractionated from Q, favoring lighter elements. Because of the unbrecciated nature of Shallowater, Q-like noble gases are considered to be primordial in origin. Fission Xe is found in Cumberland Falls, Mayo Belwa, Peña Blanca Spring, ALHA 78113 and LAP 02233. The majority of fission Xe is most likely 244Pu-derived, and about 10-20% seems to be 238U-derived at 136Xe. The observed ( 136Xe) Pu corresponds to 0.019-0.16 ppb of 244Pu, from which the 244Pu/U ratios are calculated as 0.002-0.009. These ratios resemble those of chondrites and other achondrites like eucrites, suggesting that no thermal resetting of the Pu-Xe system occurred after ˜4.5 Ga ago. We also determined oxygen isotopic compositions for four aubrites with chondritic noble gases and a new aubrite LAP 02233. In spite of their chondritic noble gas signatures, oxygen with chondritic isotopic compositions was found only in a specimen of Cumberland Falls (? 17O of ˜0.3‰). The other four aubrites and the other two measured specimens of Cumberland Falls are concurrent with the typical range for aubrites.

  2. 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.

  3. 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.

  4. Multicollector High Precision Resolution of Primordial Kr and Xe in Mantle CO2 Well Gases

    Microsoft Academic Search

    G. Holland; C. Ballentine; M. Cassidy

    2008-01-01

    Noble gas isotopes in magmatic CO2 well gases provide a unique insight into mantle volatile origin and dynamics [1-3]. Previous work has resolved mantle 20Ne\\/22Ne ratios consistent with a solar wind irradiated meteoritic source for mantle He and Ne [1]. This is distinct from Solar Wind values that might be expected if the primary mechanism of terrestrial mantle volatile acquisition

  5. Attrition resistant catalysts and sorbents based on heavy metal poisoned FCC catalysts

    Microsoft Academic Search

    S. Gangwal; K. Jothimurugesan

    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 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

  6. Mantle and Crustal Sources of Carbon, Nitrogen, and Noble gases in Cascade-Range and Aleutian-Arc Volcanic gases

    USGS Publications Warehouse

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

    2003-01-01

    Here we report anhydrous chemical (CO2, H2S, N2, H2, CH4, O2, Ar, He, Ne) and isotopic (3He/4He, 40Ar/36Ar, ?13C of CO2, ?13C of CH4, ?15N) compositions of virtually airfree 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. Helens, Mount Rainier, Mount Baker, Augustine Volcano, Mount Griggs, Trident, Mount Mageik, Aniakchak Crater, Akutan, and Makushin. The chemical and isotopic data generally point to magmatic (CO2, Ar, He), shallow crustal sedimentary (hereafter, SCS) (CO2, N2, CH4), crustal (He), and meteoric (N2, Ar) sources of volatiles. CH4 clearly comes from SCS rocks in the subvolcanic systems because CH4 cannot survive the higher temperatures of deeper potential sources. Further evidence for a SCS source for CH4 as well as for non-mantle CO2 and non-meteoric N2 comes from isotopic data that show wide variations between volcanoes that are spatially very close and similar isotopic signatures from volcanoes from very disparate areas. Our results are in direct opposition to many recent studies on other volcanic arcs (Kita and others, 1993; Sano and Marty, 1995; Fischer and others, 1998), in that they point to a dearth of subducted components of CO2 and N2 in the CRAA discharges. Either the CRAA volcanoes are fundamentally different from volcanoes in other arcs or we need to reevaluate the significance of subducted C and N recycling in convergent-plate volcanoes.

  7. Potential energy curves for the interaction of Ag(5s) and Ag(5p) with noble gas atoms.

    PubMed

    Loreau, J; Sadeghpour, H R; Dalgarno, A

    2013-02-28

    We investigate the interaction of ground and excited states of a silver atom with noble gases (NG), including helium. Born-Oppenheimer potential energy curves are calculated with quantum chemistry methods and spin-orbit effects in the excited states are included by assuming a spin-orbit splitting independent of the internuclear distance. We compare our results with experimentally available spectroscopic data, as well as with previous calculations. Because of strong spin-orbit interactions, excited Ag-NG potential energy curves cannot be fitted to Morse-like potentials. We find that the labeling of the observed vibrational levels has to be shifted by one unit. PMID:23464145

  8. USE OF SIX SIGMA TOOLS TO REDUCE NOBLE METAL LOSSES

    Microsoft Academic Search

    P. C. Brito; J. F. Morais; Monsanto Nordeste

    The objective of this work is to utilize Sixx Sigma as the methodology to optimize the chemical process in a Chemical Company. The process involves an effective use of the noble metal based catalyst in a CSTR reactor; however, noble metal losses resulted in the nature of the process has impacted on the cost of the final product. The actual

  9. Radio frequency quadrupole confined noble gas discharge laser

    Microsoft Academic Search

    M. Iberler; R. Berezov; J. Jacoby; C. Teske

    2004-01-01

    A typical multiple wavelength noble gas laser, like an argon ion laser, consists of a capacitively coupled high current density glow discharge in the presence of a magnetic field. The output power of a noble gas ion laser is extremely dependent on the current density of the discharge. Typical conditions of such a plasma are current densities (J) between 100

  10. 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

  11. 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.

  12. 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.

  13. Noble gas, alkali and alkaline atoms interacting with a gold surface

    E-print Network

    ?ach, Grzegorz; Jentschura, Ulrich D; 10.1142/S0217751X1004961X

    2013-01-01

    The attractive branch of the interaction potentials with the surface of gold have been computed for a large variety of atomic systems: the hydrogen atom, noble gases (He, Ne, Ar, Kr, Xe), alkali atoms (Li, Na, K, Rb, Cs) and alkaline atoms (Be, Mg, Ca, Sr, Ba). The results include highly accurate dynamic polarizabilities for the helium atom calculated using a variational method and explicitly correlated wavefunctions. For other atoms considered we used the data available in the literature. The interaction potentials include both the effects of retardation of the electromagnetic interactions and a realistic representation of the optical response function of gold (beyond the approximation of a perfect conductor). An explicit comparison of our result to the interaction between an atom and a perfect conductor is given.

  14. 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.

  15. Laser microprobe analyses of noble gas isotopes and halogens in fluid inclusions: Analyses of microstandards and synthetic inclusions in quartz

    SciTech Connect

    Boehlke, J.K. (Geological Survey, Reston, VA (United States)); Irwin, J.J. (Univ. of California, Berkeley (United States))

    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{sup {minus} 11} liter 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.

  16. Noble Gas Signatures in Antrim Shale Gas in the Michigan Basin - Assessing Compositional Variability and Transport Processes

    NASA Astrophysics Data System (ADS)

    Wen, T.; Castro, M. C.; Ellis, B. R.; Hall, C. M.; Lohmann, K. C.; Bouvier, L.

    2014-12-01

    Recent studies in the Michigan Basin looked at the atmospheric and terrigenic noble gas signatures of deep brines to place constraints on the past thermal history of the basin and to assess the extent of vertical transport processes within this sedimentary system. In this contribution, we present noble gas data of shale gas samples from the Antrim shale formation in the Michigan Basin. The Antrim shale was one of the first economic shale-gas plays in the U.S. and has been actively developed since the 1980's. This study pioneers the use of noble gases in subsurface shale gas in the Michigan Basin to clarify the nature of vertical transport processes within the sedimentary sequence and to assess potential variability of noble gas signatures in shales. Antrim Shale gas samples were analyzed for all stable noble gases (He, Ne, Ar, Kr, Xe) from samples collected at depths between 300 and 500m. Preliminary results show R/Ra values (where R and Ra are the measured and atmospheric 3He/4He ratios, respectively) varying from 0.022 to 0.21. Although most samples fall within typical crustal R/Ra range values (~0.02-0.05), a few samples point to the presence of a mantle He component with higher R/Ra ratios. Samples with higher R/Ra values also display higher 20Ne/22Ne ratios, up to 10.4, and further point to the presence of mantle 20Ne. The presence of crustally produced nucleogenic 21Ne and radiogenic 40Ar is also apparent with 21Ne/22Ne ratios up to 0.033 and 40Ar/36Ar ratios up to 312. The presence of crustally produced 4He, 21Ne and 40Ar is not spatially homogeneous within the Antrim shale. Areas of higher crustal 4He production appear distinct to those of crustally produced 21Ne and 40Ar and are possibly related the presence of different production levels within the shale with varying concentrations of parent elements.

  17. 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

  18. Impact event at the Permian-Triassic boundary: evidence from extraterrestrial noble gases in fullerenes.

    PubMed

    Becker, L; Poreda, R J; Hunt, A G; Bunch, T E; Rampino, M

    2001-02-23

    The Permian-Triassic boundary (PTB) event, which occurred about 251.4 million years ago, is marked by the most severe mass extinction in the geologic record. Recent studies of some PTB sites indicate that the extinctions occurred very abruptly, consistent with a catastrophic, possibly extraterrestrial, cause. Fullerenes (C60 to C200) from sediments at the PTB contain trapped helium and argon with isotope ratios similar to the planetary component of carbonaceous chondrites. These data imply that an impact event (asteroidal or cometary) accompanied the extinction, as was the case for the Cretaceous-Tertiary extinction event about 65 million years ago. PMID:11222855

  19. 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.

  20. Impact Event at the Permian-Triassic Boundary: Evidence from Extraterrestrial Noble Gases in Fullerenes

    Microsoft Academic Search

    Luann Becker; Robert J. Poreda; Andrew G. Hunt; Theodore E. Bunch; Michael Rampino

    2001-01-01

    The Permian-Triassic boundary (PTB) event, which occurred about 251.4 million years ago, is marked by the most severe mass extinction in the geologic record. Recent studies of some PTB sites indicate that the extinctions occurred very abruptly, consistent with a catastrophic, possibly extraterrestrial, cause. Fullerenes (C60 to C200) from sediments at the PTB contain trapped helium and argon with isotope

  1. Crustal Noble Gases in Jwaneng Diamonds With Links to Seismic Tomography

    Microsoft Academic Search

    M. Honda; D. Phillips; J. W. Harris; I. Yatsevich

    2005-01-01

    Recent seismic tomography studies of the Kaapvaal-Zimbabwe craton of southern Africa reveal distinct seismic velocity profiles at 150 km depth within the diamond stability field, that appear to correlate with differences in diamond paragenesis. Diamond mines with predominantly eclogitic diamond inclusions (e.g. Jwaneng, Orapa, Premier) overlie lithospheric mantle with relatively slow P-wave velocities, whereas localities with predominantly peridotitic diamond inclusions

  2. Excitation of autoionization states of the atoms of noble gases by fast electrons: argon

    SciTech Connect

    Balashov, V.V.; Grum-Grzhimailo, A.N.; Kabachnik, N.M.; Magunov, A.I.; Strakhova, S.I.

    1980-12-01

    The ionization of Ar atoms by electron impact in the neighborhood of a (3s)/sup -1/(4p)/sup 1/P autoionization state is considered theoretically. Resonance profiles are calculated for the spectra of scattered electrons and of electrons under the conditions of a (e, 2e) coincidence experiment. The calculation is carried out in the Born approximation using a Herman-Skillman model and a Hartree-Fock model with a frozen core. The sensitivity of the resonance profile to the type of electron wave functions in the continuous spectrum is analyzed. The resemblance and difference in the characteristic peculiarities are discussed in the process of excitation of partially hole autoionization states in the Ar and Ne atoms.

  3. Noble Gases in Dust Returned by Hayabusa — Clues to Asteroid Itokawa's History?

    NASA Astrophysics Data System (ADS)

    Busemann, H.; Alwmark, C.; Bajt, S.; Böttger, U.; Crowther, S. A.; Gilmour, J. D.; Heitmann, U.; Hübers, H.-W.; Meier, M. M. M.; Pavlov, S.; Schade, U.; Spring, N. H.; Weber, I.

    2014-09-01

    We discuss the first detection of Xe in asteroid Itokawa dust, the uniformly short exposure of the dust to cosmic rays, possibly resulting from the extremely fast erosion present on small asteroids, and potential implications for Itokawa’s history.

  4. Rotational Relaxation of CH379Br Molecule Caused by Noble Gases and Spherical Perturbers

    Microsoft Academic Search

    S. Gierszal; J. Galica; E. Mis-Kuzminska

    2001-01-01

    The collision-broadening coefficients have been measured for a rotational transition (J,K,F)=(1,0,5\\/2) <-- (0, 0, 3\\/2) of methyl bromide in collisions with the following perturbers: He, Ne, Ar, Kr, Xe, CH4 and CCl4. The experimental results have been interpreted on the basis of Anderson-Tsao-Curnutte theory modified by Krishnaji assuming contributions of the induction, dispersion and exchange forces.

  5. Rotational relaxation of solute molecules in dense noble gases and the relation with local anisotropy fluctuations

    Microsoft Academic Search

    Jan van der Elsken; Daan Frenkel

    1977-01-01

    Many molecular relaxation processes in fluids are sensitive to the time-dependence of local, anisotropic density fluctuations. The role played by anisotropic density fluctuations in the rotational relaxation of a linear, quantized rotor will be discussed in some detail. An expression for the dipolecorrelation function of a probe molecule, dissolved in a simple fluid, will be derived along these lines. This

  6. On the retention of primordial noble gases in the Pesyanoe meteorite

    Microsoft Academic Search

    E. R. Dufresne; Edward Anders

    1962-01-01

    A sample of the Pesyanoe meteorite has been examined by X-ray diffraction microtechnique, in an effort to find minerals of known gas-trapping tendency and thus explain the high helium content of the meteorite. Determinations of enstatite, feldspar, and troilite by earlier workers have been confirmed. The existence of many variant minor pyroxene phases, including clinopyroxene and rhombic pyroxene with stacking

  7. Noble gases and mineralogy of meteorites from China and the Grove Mountains, Antarctica: A 0

    NASA Astrophysics Data System (ADS)

    Lorenzetti, S.; Lin, Y.; Wang, D.; Eugster, O.

    2003-08-01

    We determined the mineralogical and chemical characteristics and the He, Ne, and Ar isotopic abundances of 2 meteorites that fell in China and of 2 meteorites that were recovered by the 15th Chinese Antarctic Research Expedition. Guangmingshan (H5), Zhuanghe (H5), and Grove Mountain (GRV) 98002 (L5) yield cosmic ray exposure (CRE) ages of 68.7 ± 10.0 Ma, 3.8 ± 0.6 Ma, and 17.0 ± 2.5 Ma, respectively. These ages are within the range typically observed for the respective meteorite types. GRV 98004 (H5) had an extremely short parent body-Earth transfer time of 0.052 ± 0.008 Ma. Its petrography and mineral chemistry are indistinguishable from other typical H5 chondrites. Only 3 other meteorites exist with similarly low CRE ages: Farmington (L5), Galim (LL6), and ALH 82100 (CM2). We show that several asteroids in Earth-crossing orbits, or in the main asteroid belt with orbits close to an ejection resonance, are spectrally matching candidates and may represent immediate precursor bodies of meteorites with CRE ages 0.1 Ma.

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

    E-print Network

    Goodson, B.M.

    2010-01-01

    of alkali metal atoms are polarized with laser light (Fig.Alkali metal spin-exchange optical pumping Batch optical pumping apparatus OPNMR of laser-laser beam can be directed into the magnet's bore. For a description of high-field alkali

  9. 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.

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

    E-print Network

    Goodson, B.M.

    2010-01-01

    coils Bz af coils gradient coils dBz/dz sample yb vacuum261]. Note that the gradient coils are arranged parallel togradient echo imaging sequence, and the signal was detected with a conventional Faraday induction coil.

  11. Comparison of Cosmogenic Noble Gases in Silicates and the Metal Phase of IAB Irons

    NASA Astrophysics Data System (ADS)

    Vogel, N.; Leya, I.

    2007-03-01

    We present a comparison of cosmogenic He, Ne, and Ar extracted from IAB silicates and metal groundmass. This will allow conclusions about cosmogenic production rates from IAB silicates shielded by metal and better constrain the CREAs of the IABs Landes an

  12. 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.

  13. Nanoparticle formation during laser ablation of metals at different pressures of surrounding noble gases

    Microsoft Academic Search

    R. A. Ganeev; G. S. Boltaev; R. I. Tugushev; T. Usmanov

    2010-01-01

    We demonstrate that the nanoparticle formation during laser ablation of metals by short (of a few tens of ps) laser pulses strongly depends on the concentration of surrounding gas. While, at vacuum conditions, nanoparticle formation shows very ``sharp'' atomic force microscope images of aggregated clusters, following with clear appearance of plasmon resonance on the absorption spectra of deposited films, an

  14. Determination of optical properties by third-harmonic generation in noble gases in unfocused laser beams

    Microsoft Academic Search

    W. R. Ferrell

    1985-01-01

    A new laser technique involving phase-matched third-harmonic generation in unfocused laser beams has been used to determine vacuum ultraviolet (VUV) oscillator strengths in xenon, VUV indices of refraction for the buffer gas (krypton or argon), and the VUV absorption coefficients were determined through total ionization measurements in the frequency regions of phase matching resulting from the interaction of unfocused linearly

  15. Nanoparticle formation during laser ablation of metals at different pressures of surrounding noble gases

    Microsoft Academic Search

    R. A. Ganeev; G. S. Boltaev; R. I. Tugushev; T. Usmanov

    2010-01-01

    We demonstrate that the nanoparticle formation during laser ablation of metals by short (of a few tens of ps) laser pulses\\u000a strongly depends on the concentration of surrounding gas. While, at vacuum conditions, nanoparticle formation shows very “sharp”\\u000a atomic force microscope images of aggregated clusters, following with clear appearance of plasmon resonance on the absorption\\u000a spectra of deposited films, an

  16. The atmosphere of Mars near the surface - Isotope ratios and upper limits on noble gases

    NASA Technical Reports Server (NTRS)

    Biemann, K.; Lafleur, A. L.; Owen, T.; Rushneck, D. R.; Howarth, D. W.

    1976-01-01

    Several analyses of the Martian atmosphere have been carried out with the mass spectrometer in the molecular-analysis experiment. The ratios of abundant isotopes of carbon and oxygen are within 10 per cent of terrestrial values, whereas nitrogen-15 is considerably enriched on Mars. Argon-38 has been detected, and new limits on abundances of krypton and xenon have been set. The limit on krypton is sufficiently low to suggest that the inventories of volatile substances on Mars and on earth may be distinctly different.

  17. 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 ...

  18. Evidence for multiple magma ocean outgassing and atmospheric loss episodes from mantle1 noble gases2

    E-print Network

    Mukhopadhyay, Sujoy

    ocean outgassing, with the last one likely27 being the Moon-forming giant impact. The required by plumes34 suggests that the later giant impacts including the Moon-forming giant impact did not generate a low shear wave velocity provinces (LLSVPs) at the base of the mantle, then these features37 cannot

  19. 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 ...

  20. Noble Metal Nanoparticles Applications in Cancer

    PubMed Central

    Conde, João; Doria, Gonçalo; Baptista, Pedro

    2012-01-01

    Nanotechnology has prompted new and improved materials for biomedical applications with particular emphasis in therapy and diagnostics. Special interest has been directed at providing enhanced molecular therapeutics for cancer, where conventional approaches do not effectively differentiate between cancerous and normal cells; that is, they lack specificity. This normally causes systemic toxicity and severe and adverse side effects with concomitant loss of quality of life. Because of their small size, nanoparticles can readily interact with biomolecules both at surface and inside cells, yielding better signals and target specificity for diagnostics and therapeutics. This way, a variety of nanoparticles with the possibility of diversified modification with biomolecules have been investigated for biomedical applications including their use in highly sensitive imaging assays, thermal ablation, and radiotherapy enhancement as well as drug and gene delivery and silencing. Here, we review the available noble metal nanoparticles for cancer therapy, with particular focus on those already being translated into clinical settings. PMID:22007307

  1. 40 CFR 86.1214-85 - Analytical gases.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Analytical gases. 86.1214-85 Section 86.1214-85...Emission Test Procedures for New Gasoline-Fueled, Natural Gas-Fueled, Liquefied Petroleum Gas-Fueled and Methanol-Fueled Heavy-Duty...

  2. 40 CFR 86.1214-85 - Analytical gases.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Analytical gases. 86.1214-85 Section 86.1214-85...Emission Test Procedures for New Gasoline-Fueled, Natural Gas-Fueled, Liquefied Petroleum Gas-Fueled and Methanol-Fueled Heavy-Duty...

  3. 40 CFR 86.1214-85 - Analytical gases.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 2012-07-01 false Analytical gases. 86.1214-85 Section 86.1214-85...Emission Test Procedures for New Gasoline-Fueled, Natural Gas-Fueled, Liquefied Petroleum Gas-Fueled and Methanol-Fueled Heavy-Duty...

  4. Hydrogasification of heavy oils

    Microsoft Academic Search

    Dennis E. Walsh; Nai Yuen Chen

    1983-01-01

    Thermal hydrogasification of heavy petroleum oils was investigated under conditions of short reaction time (0.5-15 s products residence time) and varied heating rates to elevated temperatures (50-850 °C\\/s to > 550 °C). Total pressures and hydrogen partial pressures up to 1500 psig were examined. Products consisted of a residual carbon fraction, light gases (primarily CHâ), and BTX. Carbon residue was

  5. 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.

  6. Mesoporous nano/micro noble metal particles: synthesis and applications

    NASA Astrophysics Data System (ADS)

    Yang, Shengchun; Luo, Xiao

    2014-04-01

    The morphology, size and composition often govern the physical and chemical properties of noble metal units with a size in the nano or micro scale. Thus, the controlled growth of noble metal crystals would help to tailor their unique properties and this would be followed by their practical application. Mesoporous nano/micro noble metal units are types of nanostructured material that have fascinating properties that can generate great potential for various applications. This review presents a general view on the growth mechanisms of porous noble metal units and is focused on recent progresses in their synthetic approaches. Then, their potential applications in the field of drug delivery, cell imaging and SERS substrates, as well as fuel cell catalysts are overviewed.

  7. 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.

  8. Isotopic studies of rare gases in terrestrial samples and natural nucleosynthesis. Progress report

    SciTech Connect

    Not Available

    1991-05-01

    This project is concerned with research in rare gas mass spectrometry. Using a two-pronged attack, we study fluids using a system (RARGA) designed for fluid analysis in bulk which is sometimes deployed in the field and a laser microprobe mass spectrometer for fluid inclusion studies. In 1991 the RARGA project continued monitoring helium isotope variations associated with renewed seismic activity in Long Valley Caldera and expanded our geothermal data base to include Lassen National Park. An important objective, continuing in 1992, 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. To this end, 1991 saw continued efforts to understand variations in composition between fluids and associated reservoir rocks and extended the data base to include fluids from the Gulf of Mexico. Our DOE work in calibrating a sensitive laser microprobe mass spectrometer for noble gases in fluid inclusions continues with successful returns particularly in calibrating neutron irradiated samples for tracing halogen ratios. In connection with observations of neutron-produced noble gas nuclides in granites, we have begun comparing measurements with calculations for both thermal and epithermal neutrons. We submitted a third paper on noble gases in diamonds, concentrating on observed effects of {sup 4}He, {sup 3}He, and fission xenon implantation from nuclear processes in adjacent material in the matrix rock. 16 refs., 1 tab.

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

    SciTech Connect

    Not Available

    1991-05-01

    This project is concerned with research in rare gas mass spectrometry. Using a two-pronged attack, we study fluids using a system (RARGA) designed for fluid analysis in bulk which is sometimes deployed in the field and a laser microprobe mass spectrometer for fluid inclusion studies. In 1991 the RARGA project continued monitoring helium isotope variations associated with renewed seismic activity in Long Valley Caldera and expanded our geothermal data base to include Lassen National Park. An important objective, continuing in 1992, 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. To this end, 1991 saw continued efforts to understand variations in composition between fluids and associated reservoir rocks and extended the data base to include fluids from the Gulf of Mexico. Our DOE work in calibrating a sensitive laser microprobe mass spectrometer for noble gases in fluid inclusions continues with successful returns particularly in calibrating neutron irradiated samples for tracing halogen ratios. In connection with observations of neutron-produced noble gas nuclides in granites, we have begun comparing measurements with calculations for both thermal and epithermal neutrons. We submitted a third paper on noble gases in diamonds, concentrating on observed effects of {sup 4}He, {sup 3}He, and fission xenon implantation from nuclear processes in adjacent material in the matrix rock. 16 refs., 1 tab.

  10. 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.

  11. Photoionization in Gases

    Microsoft Academic Search

    R. N. Varney; L. B. Loeb

    1935-01-01

    The balanced space charge positive ion detector, used in the experiments on ionization by positive alkali ions has been used in the study of photoionization in gases. The following experiments were performed: (1) A hydrogen discharge tube, operated by either a 1000- or an 8000-volt transformer, was set up so that the radiation emitted could pass through a fluorite window

  12. Gases in Seawater

    Microsoft Academic Search

    P. D. Nightingale; P. S. Liss

    2003-01-01

    The annual gross and net primary productivity of the surface oceans is similar in size to that on land (IPCC, 2001). Marine productivity drives the cycling of gases such as oxygen (O2), dimethyl sulfide (DMS), carbon monoxide (CO), carbon dioxide (CO2), and methyl iodide (CH3I) which are of fundamental importance in studies of marine productivity, biogeochemical cycles, atmospheric chemistry, climate,

  13. Upscattering Cross Sections for Ultra Cold Neutrons from Gases

    NASA Astrophysics Data System (ADS)

    Seestrom, Susan J.; UCN? Collaboration

    2014-09-01

    The scattering of ultracold neutrons (UCNs) to energies above the escape potential of a trap is called upscattering. Upscattering due to interaction with residual gases is a potential loss mechanism for UCNs stored in a trap that can impact the extracted neutron lifetime. We have developed a method for measuring the cross sections for UCN upscattering from gases stored in a small measurement cell. Upscattered neutrons are measured directly in a 3He ionization chamber and transmitted UCN strike a 10B-coated surface at the edges of the measurement cell. The transmitted UCNs are then counted with a HPGe gamma-ray detector that counts 478 keV ?-rays from the 10B(n , ??) 7Li reaction. The analysis was guided by Monte Carlo descriptions of the LANL UCN source output. We will present cross sections measured for various noble and polyatomic gases, compare these results to calculated cross sections based on models of gas scattering kernels, and use these to estimate the impact of gas upscattering on the measurement of the neutron lifetime.

  14. METHODS AND RESULTS OF RECONSTRUCTION OF NOBLE GAS RELEASES FROM THE STACKS OF THE MAYAK PA GRAPHITE REACTORS OVER THE WHOLE PERIOD OF THEIR OPERATION

    SciTech Connect

    Glagolenko, Y. V.; Drozhko, Evgeniy G.; Mokrov, Y.; Pyatin, N. P.; Rovny, Sergey I.; Anspaugh, L. R.; Napier, Bruce A.

    2008-06-01

    Brief analysis of design features and operational modes of Mayak PA industrial graphite-uranium reactors (PUGRs) is given. The above mentioned Mayak PA PUGRs determined the rates of releases of radioactive noble gases (RNG) from activation (41Ar) and fission (isotopes of Krypton and Xenon) through the vent stack of the reactor. Information is given on methods and results of experimental determination of RNG atmospheric releases for the period starting from 1965 till PUGRs decommissioning in 1987-1990. A calculation method for reconstruction of radioactive noble gas releases is proposed and justified. The results of reconstruction are given. It is shown that maximum rates of RNG releases from PUGRs high stacks were observed in the 1950s, when ordinary atmospheric air was used as a cover gas for the reactor graphite stacks and gas purification systems (flow-type gas holders) had not been installed yet.

  15. Multiple scattering of matter waves: An analytic model of the refractive index for atomic and molecular gases

    SciTech Connect

    Lemeshko, Mikhail; Friedrich, Bretislav [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany)

    2010-08-15

    We present an analytic model of the refractive index for matter waves propagating through atomic or molecular gases. The model, which combines the Wentzel-Kramers-Brillouin (WKB) treatment of the long-range attraction with the Fraunhofer model treatment of the short-range repulsion, furnishes a refractive index in compelling agreement with recent experiments of Jacquey et al. [Phys. Rev. Lett. 98, 240405 (2007)] on Li atom matter waves passing through dilute noble gases. We show that the diffractive contribution, which arises from scattering by a two-dimensional 'hard core' of the potential, is essential for obtaining a correct imaginary part of the refractive index.

  16. Noble gas atmospheric monitoring at reprocessing facilities

    SciTech Connect

    Nakhleh, C.W.; Perry, R.T. Jr.; Poths, J.; Stanbro, W.D.; Wilson, W.B.; Fearey, B.L.

    1997-05-01

    The discovery in Iraq after the Gulf War of the existence of a large clandestine nuclear-weapon program has led to an across-the-board international effort, dubbed Programme 93+2, to improve the effectiveness and efficiency of International Atomic Energy Agency (IAEA) safeguards. One particularly significant potential change is the introduction of environmental monitoring (EM) techniques as an adjunct to traditional safeguards methods. Monitoring of stable noble gas (Kr, Xe) isotopic abundances at reprocessing plant stacks appears to be able to yield information on the burnup and type of the fuel being processed. To estimate the size of these signals, model calculations of the production of stable Kr, Xe nuclides in reactor fuel and the subsequent dilution of these nuclides in the plant stack are carried out for two case studies: reprocessing of PWR fuel with a burnup of 35 GWd/tU, and reprocessing of CAND fuel with a burnup of 1 GWd/tU. For each case, a maximum-likelihood analysis is used to determine the fuel burnup and type from the isotopic data.

  17. Vibrational Relaxation in Gases

    Microsoft Academic Search

    J. D. Lambert; R. Salter

    1959-01-01

    The velocity of ultrasonic waves has been measured in a number of gases at 25 degrees C and for values of the ratio, ultrasonic frequency\\/pressure, ranging from 2 × 105 to 2 × 107 c s-1 atm-1. Dispersion, corresponding to a single vibrational relaxation process was shown by acetylene, CD3Br and hexafluoro-ethane; and, to a double relaxation process, by ethane.

  18. 169. Credit FM. Remains of H.H. Noble residence, destroyed by ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    169. Credit FM. Remains of H.H. Noble residence, destroyed by fire. 'Noble Castle' stood atop the ridge near Lakes Grace and Nora, overlooking Volta. - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

  19. A Global Dataset of Noble gas Concentrations and Their Isotopic Ratios in Volcanic Areas

    NASA Astrophysics Data System (ADS)

    Abedini, A. A.; Hurwitz, S.

    2004-12-01

    The extent to which ocean islands are derived from the deep mantle (mantle plumes) or from chemical heterogeneities embedded within the mantle convective flow has long been debated. Noble gases have unique properties that provide significant information regarding this debate and make them important geodynamic tracers. The study of noble gas isotopic compositions in active tectonic and volcanic areas is central to understanding the origins of major volcanic anomalies. For example, helium isotope composition is considered to be the most unambiguous geochemical indicator of a lower mantle plume component in surface rocks, and its variability is often taken as the strongest evidence for a layered mantle. We have compiled all the published global noble gas data from MOR, ocean islands, seamounts, and volcanic arcs, extending existing datasets which are limited to samples from oceanic rocks (Farley and Neroda, 1998; Graham, 2002). Our data set contains information on helium, neon, argon, and xenon concentrations, as well as their isotopic ratios. Where available we also included the isotopic ratios of lead, strontium, neodymium, and carbon. Overall, there are more than 5,000 entries in the database, which is sub-divided both by material sampled (e.g., volcanic glass, different minerals, fumarole, spring) and by tectonic setting (MOR, ocean islands, volcanic arcs). Our extended dataset is consistent with earlier studies and shows that helium isotope ratios in MORB glass in the Pacific, Indian and Southern Atlantic Oceans have a sharp peak between 7 and 9 RA. The large peak in MORB samples correlates with the maxima in samples from volcanic arcs, probably implying that the upper mantle has a uniform helium isotope ratio. In the North Atlantic there is a broader distribution with a maximum at 11 Ra. In contrast, helium isotope ratios in ocean-island basalts (OIB) are highly variable. As noted by previous workers, the helium isotope ratios in OIB have a large peak at 8 RA and a second peak at 13 RA, separated by a pronounced minimum at about 10 RA. In most cases, higher-than-MORB He-isotope ratios coincide with deep mantle plumes revealed by seismic tomography (Montelli et al., 2004). The database will be available through the World Wide Web and will allow examination of some unresolved scientific problems. Farley K.A., Neroda E., Ann. Rev. Earth Planet. Sci., 1998. Graham, D. W., Rev. Mineral. Geochem., 2002. Montelli, R. et al., Science. 2004.

  20. Biologically Activated Noble Metal Alloys at the Nanoscale: For Lithium Ion Battery

    E-print Network

    Ceder, Gerbrand

    of noble metal alloy nanowires with various compositions, the M13 biological toolkit extended its utility and electrochemical activity of gold and silver noble metals and their alloy nanowires using multiple virus clones versatility (E4 virus), noble metal nanowires of high-aspect ratio with diameters below 50 nm were

  1. Relativistic effects in photoionization time delay near the Cooper minimum of noble gas atoms

    E-print Network

    Kheifets, Anatoli

    Relativistic effects in photoionization time delay near the Cooper minimum of noble gas atoms Ankur the valence ns, np3/2 and np1/2 subshells of noble gas atoms in the dipole relativistic random phase to determine the time delay in Ar [8] and va- riety of noble gas atoms [9]. The notion of time

  2. Attrition resistant catalysts and sorbents based on heavy metal poisoned FCC catalysts

    Microsoft Academic Search

    Santosh Gangwal; Kandaswamy Jothimurugesan

    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

  3. Geostatistical Analysis of Tritium, 3H/3He Age and Noble Gas Derived Parameters in California Groundwater

    NASA Astrophysics Data System (ADS)

    Visser, A.; Singleton, M. J.; Moran, J. E.; Fram, M. S.; Kulongoski, J. T.; Esser, B. K.

    2014-12-01

    Key characteristics of California groundwater systems related to aquifer vulnerability, sustainability, recharge locations and mechanisms, and anthropogenic impact on recharge, are revealed in a spatial geostatistical analysis of the data set of tritium, dissolved noble gas and helium isotope analyses collected for the California State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) and California Aquifer Susceptibility (CAS) programs. Over 4,000 tritium and noble gas analyses are available from wells across California. 25% of the analyzed samples contained less than 1 pCi/L indicating recharge occurred before 1950. The correlation length of tritium concentration is 120 km. Nearly 50% of the wells show a significant component of terrigenic helium. Over 50% of these samples show a terrigenic helium isotope ratio (Rter) that is significantly higher than the radiogenic helium isotope ratio (Rrad = 2×10-8). Rter values of more than three times the atmospheric isotope ratio (Ra = 1.384×10-6) are associated with known faults and volcanic provinces in Northern California. In the Central Valley, Rter varies from radiogenic to 2.25 Ra, complicating 3H/3He dating. The Rter was mapped by kriging, showing a correlation length of less than 50 km. The local predicted Rter was used to separate tritiogenic from atmospheric and terrigenic 3He. Regional groundwater recharge areas, indicated by young groundwater ages, are located in the southern Santa Clara Basin and in the upper LA basin and in the eastern San Joaquin Valley and along unlined canals carrying Colorado River water. Recharge in California is dominated by agricultural return flows, river recharge and managed aquifer recharge rather than precipitation excess. Combined application of noble gases and other groundwater tracers reveal the impact of engineered groundwater recharge and prove invaluable for the study of complex groundwater systems. This work was performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-658313

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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

  10. Diffusivity of Lattice Gases

    NASA Astrophysics Data System (ADS)

    Quastel, Jeremy; Valkó, Benedek

    2013-10-01

    We consider one-component lattice gases with local dynamics and a stationary product Bernoulli measure on {{Z}^d}. We study the scaling exponents of the space-time correlations of the system in equilibrium at a given density. We consider a variance-like quantity computed from the correlations called the diffusivity (connected to the Green-Kubo formula) and give rigorous upper and lower bounds on it that depend on the dimension and the local behavior of the macroscopic flux function. Our results identify the cases in which the system scales superdiffusively; these cases have been predicted before, using non-rigorous scaling arguments. Our main tool is the resolvent method: the estimates are the result of a careful analysis of a complicated variational problem.

  11. 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.

  12. Making A Noble-Metal-On-Metal-Oxide Catalyst

    NASA Technical Reports Server (NTRS)

    Miller, Irvin M.; Davis, Patricia P.; Upchurch, Billy T.

    1989-01-01

    Catalyst exhibits superior performance in oxidation of CO in CO2 lasers. Two-step process developed for preparing platinum- or palladium-on-tin-oxide catalyst for recombination of CO and O2, decomposition products that occur in high-voltage discharge region of closed-cycle CO2 laser. Process also applicable to other noble-metal/metal-oxide combinations.

  13. THE LISP MACHINE: NOBLE EXPERIMENT OR FABULOUS FAILURE?

    E-print Network

    Moeller, Ralf

    THE LISP MACHINE: NOBLE EXPERIMENT OR FABULOUS FAILURE? P. T. Withington Symbolics, Inc. The "Lisp Machine", a custom computer work-station designed specifically for the execution of Lisp, has been an important part of the Lisp tradition for 20 years. Recently, the Lisp Machine has been depre- cated in view

  14. Size-dependent melting point of noble metals

    Microsoft Academic Search

    Q. Jiang; S. Zhang; M. Zhao

    2003-01-01

    A simple model, without any free parameter, is introduced to predict the size-dependent melting temperature of noble metals in this contribution. It is found that the model predictions for the melting point depression of both Au and Ag nanoparticles correspond to the experimental and computer simulation results well.

  15. Towards Visual Software Analytics Craig Anslow, James Noble,

    E-print Network

    Anslow, Craig

    visualization research the field has focused primarily on algorithm animation (1980s), software archi- tectureTowards Visual Software Analytics Craig Anslow, James Noble, Stuart Marshall School of Mathematics@cs.auckland.ac.nz Abstract Since its inception, a large amount of software has been written in Java and surprisingly little

  16. Low Field MRI of Laser Polarized Noble Gas

    Microsoft Academic Search

    G. P. Wong; C. H. Tseng; R. W. Mair; D. Hoffmann; R. E. Stoner; R. L. Walsworth; V. R. Pomeroy; F. W. Hersman; D. P. Hinton; D. G. Cory

    1999-01-01

    We describe a device for magnetic resonance imaging (MRI) of laser polarized noble gas at low magnetic fields (below 100 G). The system is robust, portable, and inexpensive, and provides gas-phase imaging resolution comparable to that of high field commercial instruments (which operate at fields ~ 1 T). At 21 G, we have imaged laser polarized ^3He gas in both

  17. Metastable noble gas apparatus for laser photoionisation studies

    Microsoft Academic Search

    J. P. Czechanski; B. H. Houston; R. B. Kay

    1989-01-01

    Metastable noble gas atoms are produced by crossing a low-energy electron sheet beam with a jet of gas injected by an automotive fuel injector. A laser beam is directed at right angles through the wide dimension of the electron beam, and the gas jet is directed at a small (19 degrees ) angle to the laser beam. An electric field

  18. Vacuum-ultraviolet noble-gas dimer lasers

    Microsoft Academic Search

    A Wayne Johnson; J. B. Gerardo; R. E. Palmer

    1976-01-01

    An experimental investigation was made of the shape and intensity of light pulses emitted by an Xe2* laser excited by a relativistic electron beam. The results obtained were used to deduce the line profile and the gain in excited xenon. The authors suggest that the majority of the results obtained should be applicable also to other noble-gas dimer lasers.

  19. Control of plasma parameters by using noble gas admixtures

    SciTech Connect

    Taylor, Kurt J.; Yun, Seokmin; Tynan, George R. [Department of Mechanical and Aerospace Engineering, and Center for Energy Research, University of California, San Diego, California 92093-0417 (United States)

    2004-09-01

    Electron temperature and density in pure He, Ar, and Xe plasmas are estimated by zero-dimensional particle and power balance equations and measured by a Langmuir probe. Both of the modeling and experimental results show that the He (Xe) plasma has the highest (lowest) electron temperature and lowest (highest) electron density for a given fill pressure and source power. We find that the electron temperature is weakly dependent on the rf power, and thus the electron density can be controlled using the rf power. The electron temperature and density are also modeled and measured in mixtures of two noble gas species. We find that the electron temperature can be controlled by altering the composition of the noble gas mixture. Thus modulation of noble gas admixture ratios and rf power allows the electron density and temperature to be controlled independently. This independent control is shown to maintained with the addition of up to 20% partial pressure of oxygen, suggesting binary noble gas admixtures may provide additional control of dissociation kinetics.

  20. NUCLEAR GENERATED PLASMAS IN NOBLE GAS THERMIONIC CONVERTERS

    Microsoft Academic Search

    F. E. Jamerson; R. H. Jr. Abrams; C. B. Leffert; R. Silver

    1963-01-01

    The generation of a plasma by fission fragment ionization in noble gas ; thermionic converters was investigated in a series of inpile experiments at the ; University of Michigan reactor. The plasma generated in Ne: Ar (1000: 1) at a ; pressure of 20 mm Hg was investigated in a plane parallel diode with electrically ; heated emitter and collector

  1. Noble metal nanoparticles for water purification: A critical review

    Microsoft Academic Search

    T. Pradeep; Anshup

    2009-01-01

    Water is one of the essential enablers of life on earth. Beginning with the origin of the earliest form of life in seawater, it has been central to the evolution of human civilizations. Noble metals have been similarly associated with the prosperity of human civilizations through their prominent use in jewellery and medical applications. The most important reason for the

  2. Corrosion control and lubrication of plated noble metal connector contacts

    Microsoft Academic Search

    Morton Antler

    1995-01-01

    There is considerable interest in the corrosion control and lubrication of separable electronic connectors and other contact-containing devices. This originates in the desire to minimize the use of costly noble metals, like gold, palladium, and their alloys, without sacrifice in reliability. When the application is in aggressive environments, pore corrosion limits the reliability of the connector. Also, there may be

  3. 8, 82738326, 2008 Greenhouse gases

    E-print Network

    Boyer, Edmond

    ACPD 8, 8273­8326, 2008 Greenhouse gases from satellite ­ Part 2: Methane O. Schneising et al.0 License. Atmospheric Chemistry and Physics Discussions Three years of greenhouse gas column-averaged dry­8326, 2008 Greenhouse gases from satellite ­ Part 2: Methane O. Schneising et al. Title Page Abstract

  4. 8, 54775536, 2008 Greenhouse gases

    E-print Network

    Boyer, Edmond

    ACPD 8, 5477­5536, 2008 Greenhouse gases from satellite ­ Part 1: CO2 O. Schneising et al. Title.0 License. Atmospheric Chemistry and Physics Discussions Three years of greenhouse gas column-averaged dry­5536, 2008 Greenhouse gases from satellite ­ Part 1: CO2 O. Schneising et al. Title Page Abstract

  5. 5, 213242, 2008 Greenhouse gases

    E-print Network

    Paris-Sud XI, Université de

    BGD 5, 213­242, 2008 Greenhouse gases German bog S. Glatzel et al. Title Page Abstract Introduction Discussions is the access reviewed discussion forum of Biogeosciences Environmental controls of greenhouse gas Correspondence to: S. Glatzel (stephan.glatzel@uni-rostock.de) 213 #12;BGD 5, 213­242, 2008 Greenhouse gases

  6. 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.

  7. 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.

  8. Gases in Seawater

    NASA Astrophysics Data System (ADS)

    Nightingale, P. D.; Liss, P. S.

    2003-12-01

    The annual gross and net primary productivity of the surface oceans is similar in size to that on land (IPCC, 2001). Marine productivity drives the cycling of gases such as oxygen (O2), dimethyl sulfide (DMS), carbon monoxide (CO), carbon dioxide (CO2), and methyl iodide (CH3I) which are of fundamental importance in studies of marine productivity, biogeochemical cycles, atmospheric chemistry, climate, and human health, respectively. For example, ˜30% of the world's population (1,570 million) is thought to be at risk of iodine-deficiency disorders that impair mental development (WHO, 1996). The main source of iodine to land is the supply of volatile iodine compounds produced in the ocean and then transferred to the atmosphere via the air-surface interface. The flux of these marine iodine species to the atmosphere is also thought to be important in the oxidation capacity of the troposphere by the production of the iodine oxide radical ( Alicke et al., 1999). A further example is that the net flux of CO2 from the atmosphere to the ocean, ˜1.7±0.5 Gt C yr-1, represents ˜30% of the annual release of anthropogenic CO2 to the atmosphere (IPCC, 2001). This net flux is superimposed on a huge annual flux (90 Gt C yr-1) of CO2 that is cycled "naturally" between the ocean and the atmosphere. The long-term sink for anthropogenic CO2 is recognized as transfer to the ocean from the atmosphere. A final example is the emission of volatile sulfur, in the form of DMS, from the oceans. Not only is an oceanic flux from the oceans needed to balance the loss of sulfur (a bioessential element) from the land via weathering, it has also been proposed as having a major control on climate due to the formation of cloud condensation nuclei (Charlson et al., 1987). Indeed, the existence of DMS and CH3I has been used as evidence in support of the Gaia hypothesis (Lovelock, 1979).There are at least four main processes that affect the concentration of gases in the water column: biological production and consumption, photochemistry, air-sea exchange, and vertical mixing. We will not discuss the effect of vertical mixing on gases in seawater and instead refer the reader to Chapter 6.08. Nor will we consider the deeper oceans as this region is discussed in chapters on benthic fluxes and early diagenesis (Chapter 6.11), the biological pump (Chapter 6.04), and the oceanic calcium carbonate cycle (Chapter 6.19) all in this volume. We will discuss the cycling of gases in surface oceans, including the thermocline, and in particular concentrate on the exchange of various volatile compounds across the air-sea interface.As we will show, while much is known about the cycling of gases such as CO2 and DMS in the water column, frustratingly little is known about many of the chemical species for which the ocean is believed to be a significant source to the atmosphere. We suspect the passage of time will reveal that the cycling of volatile compounds containing selenium and iodine may well prove as complex as that of DMS. Early studies of DMS assumed that it was produced from a precursor compound, dimethylsulfoniopropionate (DMSP), known to be present in some species of phytoplankton, and that the main sink in the water column was exchange across the air-sea interface. We now know that DMSP and DMS are both rapidly cycled in water column by a complex interaction between phytoplankton, microzooplankton, bacteria, and viruses (see Figure 1). Some detailed process experiments have revealed that only ˜10% of the total DMS produced (and less than 1.3% of the DMSP produced) is transferred to the atmosphere, with the bulk of the DMS and DMSP, either being recycled in the water column or photo-oxidized (Archer et al., 2002b).

  9. Constraints on the noble gas composition of the Icelandic plume source by laser analyses of individual vesicles in the volcanic glass DICE 11

    NASA Astrophysics Data System (ADS)

    Colin, A. P.; Moreira, M. A.; Gautheron, C.; Burnard, P.

    2014-12-01

    Models of Earth's volatile acquisition and evolution attempt to reproduce the current noble gas abundances and isotopic composition of the mantle reservoirs. The volatile composition of the OIB reservoir - assumed to preserve a higher proportion of primordial noble gases than the degassed MORB reservoir - is a strong constraint for those models. However, the correct values of the neon and argon isotopic ratios in OIBs are still a subject of debate, because of the contamination of the samples by air-derived noble gases. Although there is no consensus on the origin of this contamination - is it empty vesicles or cracks in volcanic glasses filled with seawater; air dissolution in the magma at the timing of magma eruption; assimilation of oceanic crust in the magma chamber?- targeting directly with a laser the vesicle to analyse in volcanic glasses is an efficient way to reduce this contamination. Here we present analyses of individual vesicles of an Icelandic volcanic glass, DICE 11, that was extensively studied in the past by crushing pieces of the volcanic glass under vacuum, because it was considered to have a pure plume origin. The mm-sized sample was imaged tomographically with a 5?m resolution. For opening bubbles, we used a 193nm Excimer laser to avoid diffusion of noble gases by local heating. CO2 contents were estimated by pressure measurement in the laser cell using a sensitive manometer. We analysed He and Ar isotopes, plus 22Ne abundance on a Helix SFT mass-spectrometer. We also present new He, Ne and Ar compositions obtained by step crushing on similar samples (DICE 10 and DICE 11). 3He/4He isotopic ratios are homogeneous in all the vesicles and consistent with analyses by crushing, about 18Ra. Precise 40Ar/36Ar isotopic ratios were obtained on the largest vesicles only, due to high blank contribution to the smallest vesicles, and are about 9000, i.e. the highest values obtained by step-crushing. Considering that the Ar and He isotopic compositions obtained on individual vesicles represent the mantle source values, not contaminated by air, we can precisely correct the Ne isotopic analyses obtained by crushing from air contamination; the corrected values are consistent with the value of neon-B, i.e. favour the hypothesis that the neon in OIB has an irradiated meteorite origin rather than purely solar.

  10. 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.

  11. Irradiation History of ACFER 111, Inferred from Nuclear Tracks and Rare Gases

    NASA Astrophysics Data System (ADS)

    Romstedt, J.; Pedroni, A.

    1993-07-01

    Acfer 111 is a regolith breccia consisting of H4-H6 chondritic and igneous clasts embedded in a fine-grained unequilibrated clastic matrix. The matrix has a high concentration of solar noble gases of virtually unfractionated composition [1]. To investigate the irradiation history of Acfer 111, we analyzed the cosmic ray tracks and noble gases at different locations in the meteorite. Noble gases were measured by conventional mass spectrometry. For cosmic ray track analyses, 18-200-mg fragments of nine clasts and five matrix locations were crushed and sieved. Ten to fifty grains of transparent olivine were picked from the 60-200-micrometer fractions, mounted in epoxy, polished, and etched (about 4 hr in a boiling WN solution [2]). Clasts: Out of two clasts having a small ^21Ne(sub)c excess (5-10%), one had a few grains with clearly higher track densities, the other a small amount of solar ^4He. Since the track-rich grains were not identified in situ (i.e., in an etched section), matrix contamination cannot be ruled out. The presence of preirradiated clasts, detected in many other gas-rich meteorites [see references in 4], remains an open question for Acfer 111. Clastic Matrix: Track densities at each location in the matrix show a main peak distribution that can be attributed to the galactic-cosmic-ray (GCR) irradiation of the meteoroid. Ten percent to fifty percent of the grains, however, have a track density higher than the main peak, and thus are preirradiated. Fourteen percent of these grains exhibit a steep track density gradient, indicating solar-flare irradiation at the surface of the parent body. Comparable abundances of preirradiated grains are found in the gas-rich meteorites Kapoeta and Fayetteville [3,4]. Modal and INAA analyses revealed 25-30% more metallic Fe-Ni in the matrix than in the clasts. ^21Ne(sub)c- deficits observed for matrix samples are attributed to these differing target- element chemistries. Gcr Exposure Age and Preatmospheric Size: As shown in Fig. 1, the depth- dependent main-peak track densities (owing to the meteoroid irradiation) correlate with the shielding-sensitive (^22Ne/^21Ne)(sub)c ratio. Furthermore, there is a good correlation between these two parameters and the position of the sample within the meteorite. The preatmospheric radius inferred from noble gases is at least 12 cm. Assuming production rates given by Eugster [6], the cosmic ray ages of all clasts cluster at 37.6 +/- 2 Ma. Comparing this noble gas exposure age and the measured main-peak track densities with track production rate profiles modeled for spherical meteoroids [5] and taking into account the differing track recording effiencies of olivines and pyroxenes [7], a preatmospheric meteoroid radius of 13-14 cm is inferred. The excellent agreement in size, age, and geometry found for track and noble-gas data strongly supports a single-stage exposure for Acfer 111. References: [1] Pedroni A. and Begemann F. (1992) Meteoritics, 27, 273-274. [2] Krishnaswami S. et al. (1971) Science, 174, 287-291. [3] Price P. B. et al. (1975) Proc. LSC 6th, 3449-3469. [4] Wieler R. et al. (1989) GCA, 53, 1441-1448. [5] Bhattacharya S. K. et al. (1973) JGR, 78, 8356-8363. [6] Eugster O. (1988) GCA, 52, 1649-1662. [7] Pellas P. et al. (1973) Meteoritics, 8, 418-419. Fig. 1, which appears here in the hard copy, shows the correlation between the 22Ne/21Ne ratio and track densities.

  12. 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.

  13. Discharges In Electronegative Gases

    NASA Astrophysics Data System (ADS)

    Franklin, R. N.

    2008-10-01

    This talk will come in three parts. First, the early work in electronegative plasmas, principally by Emeleus and co-workers in Iodine, and by Massey and co-workers in Oxygen. They were at opposite ends of the ``spectrum'' of electronegativity - the ratio of negative ion density to electron density. Secondly, we cover in more detail work in Oxygen, where in retrospect we know that too many parameters were included to reveal the underlying structure of electronegative plasmas. That is associated with Edgley and von Engel, and later with Ferriera and co-workers. From there until the present day we describe work coming from different directions, showing that by questioning prior assumptions, we have arrived at our present understanding. The basic elements are, that in general there is a negative ion core, surrounded by a conventional plasma, and that at low pressures the situation is significantly different from higher pressures. The talk will seek to avoid mathematical complexity and concentrate on the physics, explaining the reason for previous differences, and show the way forward for a more Complete understanding of the very complex problem of strongly electronegative plasmas and their structure when diluted by rare gases. All of this involves a multiplicity of ion species of both signs, and a variety of reaction rates.

  14. Investigating and Using Biomass Gases

    NSDL National Science Digital Library

    Eric Benson

    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.

  15. Process of selectively desulfurizing gases

    SciTech Connect

    Doerges, A.; Kempf, G.; Schlauer, J.

    1981-10-27

    In a process of selectively desulfurizing gases which contain hydrogen sulfide and carbon dioxide comprising scrubbing the gases with an aqueous potassium carbonate solution under superatmospheric pressure and at temperatures of about 100* C., regenerating the laden scrubbing solution and recycling the regenerated scrubbing solution, the improvement wherein the gases to be purified are scrubbed with an aqueous potassium carbonate solution so as to maintain a mass ratio of 1.0 to 3.0 vals (Gram equivalents) of alkali in the solution per mole of co2 and h2s in the gases to be purified, the laden scrubbing liquor is subsequently regenerated by being stripped with a gas in which a co2 partial pressure above 0.2 bar is maintained, and the so regenerated scrubbing solution is recycled.

  16. Process of selectively desulfurizing gases

    SciTech Connect

    Schlauer, J.; Kempf, G.; Doerges, A.

    1981-10-27

    This process selectively desulfurizes gases which contain hydrogen sulfide and carbon dioxide. It is comprised of scrubbing the gases with an aqueous potassium carbonate solution under superatmospheric pressure and at temperatures of ca. 100 c. The laden scrubbing solution is regenerated and the regenerated scrubbing solution is recycled. In turn, the gases to be purified are scrubbed with an aqueous potassium carbonate solution so as to maintain a mass ratio of 1.0 to 3.0 vals (gram equivalents) of alkali in the solution per mole of CO/sub 2/ and H/sub 2/S in the gases to be purified. The laden scrubbing liquor is subsequently regenerated by being stripped with a gas in which a CO/sub 2/ partial pressure above 0.2 bar is maintained, and the regenerated scrubbing solution is recycled. 7 claims.

  17. Degenerate quantum gases of strontium

    E-print Network

    Stellmer, Simon; Killian, Thomas C

    2013-01-01

    Degenerate quantum gases of alkaline-earth-like elements open new opportunities in research areas ranging from molecular physics to the study of strongly correlated systems. These experiments exploit the rich electronic structure of these elements, which is markedly different from the one of other species for which quantum degeneracy has been attained. Specifically, alkaline-earth-like atoms, such as strontium, feature metastable triplet states, narrow intercombination lines, and a non-magnetic, closed-shell ground state. This review covers the creation of quantum degenerate gases of strontium and the first experiments performed with this new system. It focuses on laser-cooling and evaporation schemes, which enable the creation of Bose-Einstein condensates and degenerate Fermi gases of all strontium isotopes, and shows how they are used for the investigation of optical Feshbach resonances, the study of degenerate gases loaded into an optical lattice, as well as the coherent creation of Sr_2 molecules.

  18. Noble Gas Excimer Detectors for Security and Safeguards Applications

    SciTech Connect

    Hynes, Michael V.; Lanza, Richard [Nuclear Science and Engineering Department Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Chandra, Rico; Davatz, Giovanna [Arktis Radiation Detectors, Zurich, CH (Switzerland)

    2011-12-13

    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.

  19. Hydrodynamics of unitary Fermi gases

    NASA Astrophysics Data System (ADS)

    Young, Ryan E.

    Unitary fermi gases have been widely studied as they provide a tabletop archetype for re- search on strongly coupled many body systems and perfect fluids. Research into unitary fermi gases can provide insight into may other strongly interacting systems including high temperature superconductor, quark-gluon plasmas, and neutron stars. Within the unitary regime, the equilib- rium transport coefficients and thermodynamic properties are universal functions of density and temperature. Thus, unitary fermi gases provide a archetype to study nonperturbative many-body physics, which is of fundamental significance and crosses several fields. This thesis reports on two topics regarding unitary fermi gases. A recent string theory conjecture gives a lower bound for the dimensionless ratio of shear viscosity of entropy, ?/s ? 4pi /kb . Unitary fermi gases are a candidate for prefect fluids, yet ?/s is well above the string theory bound. Using a stochastic formulation of hydrodynamics, we calculate a lower bound for this ratio accounting for the momentum dissipation from fluctuations. This lower bound is in good agreement with both theoretical and experimental results. The second question addressed is the simulation of elliptic flow. Elliptic flow, first observed in 2002, is a characteristic of strongly coupled systems and has been studied in both quark-gluon plasmas and unitary fermi gases. As such, simulations of these systems are of interest. We test a variety of lattice Boltzmann models and compare the simulation results to the theoretical and experimental findings.

  20. 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

  1. 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.

  2. Infrared spectra of formic acid clusters in noble gas matrices

    NASA Astrophysics Data System (ADS)

    Ito, Fumiyuki

    2015-07-01

    Infrared absorption spectra of formic acid clusters (HCOOH)n have been observed in noble gas matrices (Ar, Kr and Xe). The concentration dependence of the spectra and a comparison with the assigned monomeric/dimeric bands has led to the assignment of polymeric species (HCOOH)n (n > 2). From comparisons of these spectra with several sets of DFT calculations, we concluded that the observed polymeric species can be assigned to stable isomers of (HCOOH)3.

  3. Nuclear magnetic resonance experiments using laser- polarized noble gas

    Microsoft Academic Search

    Glenn Patrick Teen Chung Wong

    2001-01-01

    Three different nuclear magnetic resonance (NMR) experiments using laser-polarized noble gas are reported. The first experiment demonstrates the feasibility of fast low magnetic field (~20 G) magnetic resonance imaging (MRI) with comparable resolution and signal-to-noise of conventional high magnetic field (~1 T) MRI. In addition, advantages of low field imaging over high field imaging are shown for certain applications. The

  4. Low-field MRI of laser polarized noble gas.

    PubMed

    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

    1998-10-26

    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. PMID:11543589

  5. Resonance in scattering and absorption from large noble gas clusters.

    PubMed

    Zweiback, J S; Ditmire, T; Perry, M

    2000-06-01

    Light scattering in large noble gas clusters irradiated by intense laser pulses was studied and compared to absorption measurements. The scattering signal shows the presence of a peak, when the pulse width was varied, similar to one previously reported in absorption measurements. The peak of the scattering, however, occurs at a longer pulse width than for absorption. This result disagrees with a simple simulation and may be due to propagation or non-linear effects not included in the model. PMID:19404356

  6. Noble Gas Partitioning Between Olivine and Melt to 2 GPa

    Microsoft Academic Search

    S. W. Parman; S. P. Kelley; C. J. Ballentine; J. A. van Orman; G. Holland

    2009-01-01

    We have extended our experimental measurements of noble gas partition coefficients to 2 GPa in the piston-cylinder device. The experimental set-up involves surrounding wafers of gem quality San Carlos olivine (250-1000 microns thick, 3-4 mm diameter) with diamond powder or vitreous carbon spheres. A layer of melt is placed at the bottom of the capsule which infiltrates the porous media

  7. Noble Gas Broadening in Fundamental Bands of H 2S

    Microsoft Academic Search

    B. Sumpf; I. Meusel; H.-D. Kronfeldt

    1997-01-01

    For 23 lines from all three fundamental bands of H2S, noble gas broadening coefficients were measured applying a two-channel diode laser spectrometer in pulsed mode. Altogether for 17 lines from the ?1band (3 ?J? ? 17, 0 ?Ka?? 6), 1 line from the ?2band (J? = 4,Ka?= 3), and 5 lines from the ?3band (3 ?J? ? 7, 1 ?Ka??

  8. 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.

  9. Colloidal Synthesis and Nanocharacterization of Engineered Noble Metal Nanoparticles

    Microsoft Academic Search

    Kenechukwu Onubogu; Iliana Medina-Ramirez; Sajid Bashir; Zhiping Luo; Jingbo Liu

    2011-01-01

    Engineered noble (silver [Ag], gold [Au], and platinum [Pt]) metallic nanoparticles (ENPs) were prepared in gum arabic solutions using a facile, economical, and nontoxic synthetic route. Advanced instrumentation techniques (ultraviolet-visible spectroscopy, X-ray powder diffraction, high-resolution transmission electron microscopy equipped with X-ray energy dispersive spectroscopy, and dynamic light scattering) were applied to characterize the morphology, particle size distribution, elemental composition, and

  10. 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.

  11. Noble gas and halogen geochemistry of mantle fluids: comparison of African and Canadian diamonds

    NASA Astrophysics Data System (ADS)

    Johnson, L. H.; Burgess, R.; Turner, G.; Milledge, H. J.; Harris, J. W.

    2000-02-01

    Volatile-bearing fluids in diamond have been characterised using extension of the 40Ar- 39Ar technique to simultaneously measure noble gas isotopes, halogens (Cl, Br and I), K and U. Samples investigated include opaque cubic and fibrous diamonds from the North West Territories, Canada, the Democratic Republic of Congo, (DRC, formerly Zaire), and Jwaneng, Botswana. These are compared with results obtained from metasomatised mantle xenoliths from Bultfontein, South Africa. Diamonds and xenoliths show a narrow range of 40Ar?/Cl values between 506-1347 × 10 -6 molar (M) with mean values that overlap for African diamonds and xenoliths (831 ± 218 × 10 -6 M) and Canadian diamonds (965 ± 273 × 10 -6 M). These values are consistent with the estimated MORB value and support the presence of a widespread 40Ar and Cl-rich fluid in the mantle. Canadian diamonds have high and variable halogen ratios, with Br/Cl = 1.3-63.0 × 10 -3 M and I/Cl = 9.8-1703.5 × 10 -6 M. In contrast, African diamonds, have less variable Br/Cl = 1.0-2.0 × 10 -4 M and I/Cl = 13.6-176.4 × 10 -6 M (with most I/Cl between 20-70 × 10 -6 M). Fluids in diamonds from DRC and Botswana, have Ar and halogen compositions close to those estimated for the present-day MORB source. The concentrations of noble gases (Ar, Kr and Xe), halogens, K and U in Canadian coated stones are 10-30 times higher than in African coated stones probably due to a higher inclusion population density. The large variation in halogen ratios measured in Canadian diamonds is the first evidence for significant halogen fractionation in the mantle. The Br/Cl ratios are notably above the range reported for crustal fluids. The high halogen ratios in Canadian diamonds are consistent with crystallisation of a Cl-bearing mineral, possibly involving apatite, from a fluid with starting composition similar to that in African diamonds.

  12. Hydrochemistry and noble gas origin of geothermal waters of Icheon and Pocheon area in South Korea

    NASA Astrophysics Data System (ADS)

    Jeong, Chan Ho; Shin, Seon Ho; Nagao, Keisuke; Kim, Kyu Han; Koh, Yung Kwon; Kim, Gun Young

    2010-05-01

    Hydrochemical, stable isotopic (?18O and ?D) and noble gas isotopic analyses of seven geothermal water samples, eleven groundwater samples and six surface water samples collected from the Icheon and Pocheon area were carried out to find out hydrochemical characteristics, and to interpret the source of noble gases and the geochemical evolution of the geothermal waters. The geothermal waters show low temperature type ranging from 21.5 to 31.4 ? and the pH value between 6.69 and 9.21. Electrical conductivity of geothermal waters has the range from 310 to 735 ?S/cm. Whereas the geothermal in the Icheon area shows the geochemical characteristics of neutral pH, the Ca-HCO3(or Ca(Na)-HCO3) chemical type and a high uranium content, the geothermal water in the Pocheon area shows the characteristics of alkaline pH, the Na-HCO3 chemical type and a high fluorine content. These characteristics indicate that the geothermal water in the Icheon area is under the early stage in the geochemical evolution, and that geothermal water in the Pocheon area has been geochemically evolved. The ?18O and ?D values of geothermal waters show the range of -10.1˜-8.69‰ and from -72.2˜-60.8‰, respectively, and these values supply the information of the recharge area of geothermal waters. The 3He/4He ratios of the geothermal waters range from 0.09×10-6 to 0.65×10-6 which are plotted above the mixing line between air and crustal components. Whereas the helium gas in the Icheon geothermal water was mainly provided from the atmospheric source mixing with the mantle(or magma) origin, the origin of helium gas in the Pocheon geothermal water shows a dominant crustal source. 40Ar/36Ar ratios of geothermal water are in the range of an atmosphere source. Key words: hot spring water, hydrochemical composition, low temperature type, 3He/4He ratios, crustal source

  13. Asphaltene Deposition During Steam-Assisted Gravity Drainage: Effect of Non-Condensable Gases

    Microsoft Academic Search

    Serhat Canbolat; Serhat Akin; Anthony R. Kovscek

    2006-01-01

    Asphaltene deposition was investigated during laboratory-scale steam-assisted gravity drainage (SAGD) experiments to probe in situ upgrading of a heavy oil. Tests were conducted with and without the addition of non-condensable gases (carbon dioxide or n-butane) to the steam. The apparatus was a three-dimensional scaled physical model packed with crushed limestone saturated with 12.4° API heavy-crude oil. Temperature, pressure, and production

  14. Unusual noble gas compositions in polycrystalline diamonds: preliminary results from the Jwaneng kimberlite, Botswana

    Microsoft Academic Search

    Masahiko Honda; David Phillips; Jeffrey W. Harris; Igor Yatsevich

    2004-01-01

    We have undertaken noble gas analyses of four polycrystalline framesite diamonds from the Jwaneng kimberlite pipe, Botswana. These samples yielded complex, multiple noble gas components (crustal, atmospheric and in situ radiogenic\\/fissiogenic), which were successfully deconvoluted by combining vacuum crushing and step-heating experiments and examining a full suite of noble gas isotope and elemental abundances.The most striking observation is the presence

  15. 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 ...

  16. Noble Gas-Actinide Compounds: Complexation of the CUO Molecule by Ar, Kr, and Xe Atoms in Noble Gas Matrices

    Microsoft Academic Search

    Jun Li; Bruce E. Bursten; Binyong Liang; Lester Andrews

    2002-01-01

    The CUO molecule, formed from the reaction of laser-ablated U atoms with CO in a noble gas, exhibits very different stretching frequencies in a solid argon matrix [804.3 and 852.5 wave numbers (cm-1)] than in a solid neon matrix (872.2 and 1047.3 cm-1). Related experiments in a matrix consisting of 1% argon in neon suggest that the argon atoms are

  17. 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.

  18. Noble Metals and Spinel Settling in High Level Waste Glass Melters

    SciTech Connect

    Sundaram, S. K.; Perez, Joseph M.

    2000-09-30

    In the continuing effort to support the Defense Waste Processing Facility (DWPF), the noble metals issue is addressed. There is an additional concern about the amount of noble metals expected to be present in the future batches that will be considered for vitrification in the DWPF. Several laboratory, as well as melter-scale, studies have been completed by various organizations (mainly PNNL, SRTC, and WVDP in the USA). This letter report statuses the noble metals issue and focuses at the settling of noble metals in melters.

  19. Electrochemical Synthesis of Nanostructured Noble Metal Films for Biosensing

    NASA Astrophysics Data System (ADS)

    Bhattarai, Jay K.

    Nanostructures of noble metals (gold and silver) are of interest because of their important intrinsic properties. Noble metals by themselves are physically robust, chemically inert, highly conductive, and possess the capability to form strong bonds with thiols or dithiol molecules present in organic compounds, creating self-assembled monolayers with tunable functional groups at exposed interfaces. However, when the nanostructures are formed, they in addition possess high surface area and unique optical properties which can be tuned by adjusting the shape and the size of the nanostructures. All of these properties make nanostructures of noble metals suitable candidates to be used as a transducer for optical and electrochemical biosensing. Individual nanostructures might be easier to prepare but difficult to handle to use as a transducer. Therefore, we prepared and analyzed nanostructured films/coating of noble metals and used them as a transducer for optical and electrochemical biosensing. We have electrochemically prepared nanoporous gold (NPG) on gold wire varying different dependable parameters (deposition potential, time, and compositional ratio) to obtain an optimal structure in term of stability, morphology, and better surface area. NPG prepared using a deposition potential of --1.0 V for 10 min from 30:70% 50 mM potassium dicyanoaurate(I) and 50 mM potassium dicyanoargentate(I) was used as an optimal surface for protein immobilization, and to perform square wave voltammetry (SWV) based enzyme-linked lectinsorbent assays. On flat gold surfaces, adjacent protein molecules sterically block their active sites due to high-density packing, which can be minimized using NPG as a substrate. NPG can also show significant peak current in SWV experiments, a sensitive electrochemical technique that minimizes non-Faradaic current, which is difficult to obtain using a flat gold surface. These all make NPG a suitable substrate, electrode, and transducer to be used in electrochemical biosensing. We have also discovered a facile electrochemical method to synthesize novel plasmonic noble metal nanostructured films. Plasmonic noble metal nanostructures have promising applications in photovoltaic solar cells, cloaking, and molecular sensing. Here, we used plasmonic noble metal nanostructures as a transducer for biosensing using localized surface plasmon resonance (LSPR) spectroscopy, a label-free biosensing technique. The prepared nanostructured films are not only sensitive for detecting biomolecules, but are stable chemically and physically, and can be easily regenerated. We have compared the sensitivity of three different types of nanostructured films, namely; nanostructured gold film (NGF), nanostructured silver film (NSF), and NPG film, and discussed the advantages and disadvantages of the prepared structures. Finally, we report carbohydrate--lectin, lectin--protein, and layer-by-layer interactions of molecules using LSPR spectroscopy. We have also performed real-time interactions and concentration dependent studies to find the equilibrium dissociation constant of the interactions. The results from these experiments could contribute to the development of cheap and sensitive biosensors that can be used for diagnostic purposes.

  20. 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.

  1. Cross-Calibration of Secondary Electron Multiplier in Noble Gas Analysis

    NASA Astrophysics Data System (ADS)

    Santato, Alessandro; Hamilton, Doug; Deerberg, Michael; Wijbrans, Jan; Kuiper, Klaudia; Bouman, Claudia

    2015-04-01

    The latest generation of multi-collector noble gas mass spectrometers has decisively improved the precision in isotopic ratio analysis [1, 2] and helped the scientific community to address new questions [3]. Measuring numerous isotopes simultaneously has two significant advantages: firstly, any fluctuations in signal intensity have no effect on the isotope ratio and secondly, the analysis time is reduced. This particular point becomes very important in static vacuum mass spectrometry where during the analysis, the signal intensity decays and at the same time the background increases. However, when multi-collector analysis is utilized, it is necessary to pay special attention to the cross calibration of the detectors. This is a key point in order to have accurate and reproducible isotopic ratios. In isotope ratio mass spectrometry, with regard to the type of detector (i.e. Faraday or Secondary Electron Multiplier, SEM), analytical technique (TIMS, MC-ICP-MS or IRMS) and isotope system of interest, several techniques are currently applied to cross-calibrate the detectors. Specifically, the gain of the Faraday cups is generally stable and only the associated amplifier must be calibrated. For example, on the Thermo Scientific instrument control systems, the 1011 and 1012 ohm amplifiers can easily be calibrated through a fully software controlled procedure by inputting a constant electric signal to each amplifier sequentially [4]. On the other hand, the yield of the SEMs can drift up to 0.2% / hour and other techniques such as peak hopping, standard-sample bracketing and multi-dynamic measurement must be used. Peak hopping allows the detectors to be calibrated by measuring an ion beam of constant intensity across the detectors whereas standard-sample bracketing corrects the drift of the detectors through the analysis of a reference standard of a known isotopic ratio. If at least one isotopic pair of the sample is known, multi-dynamic measurement can be used; in this case the known isotopic ratio is measured on different pairs of detectors and the true value of the isotopic ratio of interest can be determined by a specific equation. In noble gas analysis, due to the decay of the ion beam during the measurement as well as the special isotopic systematic of the gases themselves, the cross-calibration of the SEM using these techniques becomes more complex and other methods should be investigated. In this work we present a comparison between different approaches to cross-calibrate multiple SEM's in noble gas analysis in order to evaluate the most suitable and reliable method. References: [1] Mark et al. (2009) Geochem. Geophys. Geosyst. 10, 1-9. [2] Mark et al. (2011) Geochim. Cosmochim. 75, 7494-7501. [3] Phillips and Matchan (2013) Geochimica et Cosmochimica Acta 121, 229-239. [4] Koornneef et al. (2014) Journal of Analytical Atomic Spectrometry 28, 749-754.

  2. 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.

  3. Hot Topics in Cold Gases

    E-print Network

    Robert Seiringer

    2009-08-25

    Since the first experimental realization of Bose-Einstein condensation in cold atomic gases in 1995 there has been a surge of activity in this field. Ingenious experiments have allowed us to probe matter close to zero temperature and reveal some of the fascinating effects quantum mechanics has bestowed on nature. It is a challenge for mathematical physicists to understand these various phenomena from first principles, that is, starting from the underlying many-body Schr\\"odinger equation. Recent progress in this direction concerns mainly equilibrium properties of dilute, cold quantum gases. We shall explain some of the results in this article, and describe the mathematics involved in understanding these phenomena. Topics include the ground state energy and the free energy at positive temperature, the effect of interparticle interaction on the critical temperature for Bose-Einstein condensation, as well as the occurrence of superfluidity and quantized vortices in rapidly rotating gases.

  4. INCREASE OF NOZZLE'S SEPARATION OF ISOTOPES BY ADDITION OF LIGHT GASES

    Microsoft Academic Search

    E. W. Becker; K. Bier; W. Bier

    1961-01-01

    Since the addition of a light gas to the isotopic mixtures to be ; separated by the separation nozzle process increases the mass difference of the ; isotopes, it is to be expected that the separation of heavy isotopes could be ; increased by the addition of gases with low molecular weight. This effect was ; studied on a mixture

  5. [CFC gases in medicinal sprays].

    PubMed

    Pedersen, P H; Svendsen, U G

    1989-03-20

    In 1987, approximately 1.18 million aerosol dispensers for medicinal use were sold in Denmark. These contained approximately 29 tons of completely halogenized CFC gases ("Freon") and the preparations were employed for the treatment of bronchial asthma and rhinitis. The possibilities of substitutes are discussed in this article. Preparations are already available which do not contain CFC. Producers of CFC are also attempting to develop new aerosol gases which do not damage the environment. Perhaps these will be found in medicinal preparations in the future. PMID:2711484

  6. 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.

  7. A noble gas tool to quantify the interaction of groundwater with coalbed methane, San Juan Basin, USA

    NASA Astrophysics Data System (ADS)

    Zhou, Z.; Ballentine, C. J.; Kipfer, R.; Schoell, M.; Thibodeaux, S.

    2003-04-01

    The role of groundwater in both generating coalbed methane and for assessing the competency of this type of site for CO2 disposal remains an open question. This project develops the noble gas isotopes as a tracer of groundwater involvement in the San Juan, USA, coalbed methane reservoir, a case-type system. 26 samples have been collected for compositional, stable isotope and noble gas determination. Of these, 8 were control samples from the underpressured low production region south of the basin structural hingeline. The remaining samples were from the hydrodynamically overpressured and high methane production region to the north of the hingeline. 3He/4He and 40Ar/36Ar ratios increase consistently according to their distance to the northwest basin margin recharge area. Both water-derived (e.g. 20Ne and 36Ar) and radiogenic noble gases (e.g. 4He and 40Ar*) can be resolved and follow a simple Rayleigh fractionation model, suggesting that they are mixed in groundwater before the fractionation occurs. Low 20Ne concentrations in gas samples can be accounted for by dilution of the groundwater-associated gas by desorbed coalbed methane. This model allows us to quantify the amount of water associated with gas production at each well, ranging up to 24500 m3 (H2O). The results show that the gas wells close to the basin margin recharge area have seen significantly more water than gas wells towards the basin center. However, there are orders of magnitude more water associated per unit production of gas for the wells in the underpressured region than gas wells in the overpressured region. This model also allows us to calculate the initial radiogenic 4He concentrations in the undegassed groundwater. By assuming an average crustal 4He flux, the 4He groundwater age at each well can be calculated. In the overpressured region, 4He groundwater ages are typically between 2,000-5,000 years with a slightly older average age for the underpressured region.

  8. 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.

  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. Catalytic oxidation of carbon nanotubes with noble metal nanoparticles.

    PubMed

    Yoshida, Kaname; Arai, Shigeo; Sasaki, Yukichi; Tanaka, Nobuo

    2015-09-01

    Catalytic oxidation of multi-walled carbon nanotubes (MWNCTs) with some noble metal nanoparticles was observed by environmental transmission electron microscopy (E-TEM). Amoeba-like movement of the nanoparticles was observed even at a temperature of ?400°C, which is much lower than the melting points of any of the metals. In particular, rhodium particles reacted intensely with MWCNTs, and assumed a droplet-like shape. On the other hand, gold particles caused very little erosion of the MWCNTs under the conditions of this study. PMID:26025589

  11. Are matrix isolated species really “isolated”? Infrared spectroscopic and theoretical studies of noble gas-transition metal oxide complexes

    Microsoft Academic Search

    YanYing Zhao; MingFei Zhou

    2010-01-01

    In this review, we summarize our recent results on matrix isolation infrared spectroscopic studies and theoretical investigations\\u000a of noble gas-transition metal oxide complexes. The results show that some transition metal oxide species trapped in solid\\u000a noble gas matrices are chemically coordinated by one or multiple noble gas atoms forming noble gas complexes and, hence, cannot\\u000a be regarded as isolated species.

  12. Electron beam process for SO 2 removal from flue gases with high SO 2 content

    NASA Astrophysics Data System (ADS)

    Licki, J.; Chmielewski, A. G.; Zimek, Z.; Tymiñski, B.; Bu?ka, S.

    2002-03-01

    Flue gases with high SO 2 concentration are emitted from different industrial processes, e.g. combustion of coal with high sulfur content, copper smelting and sintering plant. The application of the electron beam process for SO 2 removal from such flue gases was investigated. A parametric study was carried out to determine the removal efficiency as a function of temperature and humidity of irradiated gases, dose and ammonia stoichiometry. At the dose 11.5 kGy 95% SO 2 removal efficiency was obtained when the temperature and humidity of irradiated flue gases and ammonia stoichiometry were properly adjusted. The synergistic effect of high SO 2 concentration on NO x removal was observed. The collected by-product was the mixture of (NH 4) 2 SO 4 and NH 4NO 3. The content of heavy metals in the by-product was many times lower than the values acceptable for commercial fertilizer.

  13. The Behavior and Effects of the Noble Metals in the DWPF Melter System

    Microsoft Academic Search

    M. E. Smith; D. F. Bickford

    1997-01-01

    Governments worldwide have committed to stabilization of high-level nuclear waste (HLW) by vitrification to a durable glass form for permanent disposal. All of these nuclear wastes contain the fission-product noble metals: ruthenium, rhodium, and palladium. SRS wastes also contain natural silver from iodine scrubbers. Closely associated with the noble metals are the fission products selenium and tellurium which are chemical

  14. Catalytic decomposition of N 2O over monolithic supported noble metal-transition metal oxides

    Microsoft Academic Search

    Viviane Boissel; Saad Tahir; Carolyn Ann Koh

    2006-01-01

    The decomposition of nitrous oxide to nitrogen and oxygen using a series of monolithic (ceria-alumina washcoated cordierite) supported transition metal (Cu, Fe, Co, Ni, Mn) and noble metal (Ir, Rh) oxide catalysts has been studied using gas chromatography. The effect of combining a transition metal with a noble metal has also been investigated. A synergetic effect was observed between transition

  15. 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,...

  16. Surface Plasmon Resonance (SPR) Electron and Energy Transfer in Noble Metal-Zinc Oxide Composite Nanocrystals

    E-print Network

    Kim, Tae-Geun

    Surface Plasmon Resonance (SPR) Electron and Energy Transfer in Noble Metal-Zinc Oxide Composite tagging, drug delivery, chemical sensors, catalysts, and photovoltaics.9­11 ZnO is a wide energy band gap is beneficial to light absorption/emission or electron transfer. Nanometer-scale noble metals have been

  17. Excited states in the alkali/noble metal surface systems: A model system for the

    E-print Network

    Aeschlimann, Martin

    Review Excited states in the alkali/noble metal surface systems: A model system for the study Kaiserslautern, Germany Abstract The low coverage adsorption of alkalis on metal surfaces induces excited states investiga- tions of alkalis adsorbed on noble metal surfaces, with emphasis on the characteristics

  18. A study of Stark effects of Rydberg p states of noble gas atoms

    Microsoft Academic Search

    T. Jiang; M. D. Bowden; E. Wagenaars; E. Stoffels; G. M. W. Kroesen

    2006-01-01

    We have studied the Stark effect for Rydberg p states of noble gas atoms using laser optogalvanic spectroscopy. The measurements were performed in the sheath region of noble gas glow discharges. Laser excitation from metastable states to np states was monitored by optogalvanic spectroscopy. Clear Stark shifts were observed and the experimental results were compared with a theoretical calculation based

  19. Relativistic effects in photoionization time delay near the Cooper minimum of noble gas atoms

    E-print Network

    Kheifets, Anatoli

    Relativistic effects in photoionization time delay near the Cooper minimum of noble gas atoms/2 and np1/2 subshells of noble gas atoms is theoretically scrutinized within the framework of the dipole) [4]. In these devices, the phase stabilized electric field of a short laser pulse is used to convert

  20. Photodissociative generation of population inversion in alkali noble gas excimer systems

    Microsoft Academic Search

    S. Shahdin; K. Ludewigt; B. Wellegehausen

    1981-01-01

    Experiments on the production of alkali noble gas excimer molecules by photodissociation with UV excimer laser radiation were reported. The experiments were conducted with NaI-Xe and CsI-Xe systems excited by 193 nm ArF or 249 KrF laser radiation. The possibility of realizing an optically pumped alkali noble gas excimer laser is discussed.

  1. Shape Control of PbSe Nanocrystals Using Noble Metal Seed Particles

    E-print Network

    Swihart, Mark T.

    Shape Control of PbSe Nanocrystals Using Noble Metal Seed Particles Ken-Tye Yong,,§ Yudhisthira by seeding their growth with noble metal nanoparticles (Au, Ag, or Pd) and varying the seed and precursor used to grow a variety of nanowires on solid substrates seeded with catalyst particles. This approach

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

    Microsoft Academic Search

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

    2007-01-01

    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,

  3. A new noble gas paleoclimate record in Texas --- Basic assumptions revisited

    Microsoft Academic Search

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

    2007-01-01

    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,

  4. Ultrafast dynamics in noble metal clusters: The role of internal vibrational redistribution

    Microsoft Academic Search

    Vlasta Bonacic-Koutecký; Roland Mitric; Christian Bürgel; Melanie Nößler

    2008-01-01

    We present a theoretical study of the ultrafast dynamics in noble metal clusters interacting with molecular oxygen which is of fundamental importance for the understanding and design of cluster-based heterogenous nanocatalysts. We demonstrate that intrinsic dynamical properties can significantly promote the reactivity of small noble metal clusters towards O2. This concept is illustrated by performing collision simulations between Ag6- and

  5. Solubility of solutes in compressed gases: Dilute solution theory

    SciTech Connect

    Wang, X.; Tavlarides, L.L. (Syracuse Univ., NY (United States). Dept. of Chemical Engineering)

    1994-03-01

    A dilute solution theory is developed for describing the thermodynamic behavior of a compressed gaseous dilute solution. The considerations follow generally accepted statistical treatments for describing dilute liquid solutions. The theory is self-consistent with the ideal gas law for dilute gases and with Henry's law for dilute liquid (or solid) solutions. Further, it provides a simple linear relationship which represents well the solubility behavior of a heavy solute (solid or liquid) in a gaseous solvent over relatively wide density regions of the solvent (i.e., 0 [le] [rho] [le] 2.0/V[sub c]).

  6. Noble gas-transition-metal complexes: coordination of VO2 and VO4 by Ar and Xe atoms in solid noble gas matrixes.

    PubMed

    Zhao, Yanying; Gong, Yu; Chen, Mohua; Zhou, Mingfei

    2006-02-01

    The matrix isolation infrared spectroscopic and quantum chemical calculation results indicate that vanadium oxides, VO2 and VO4, coordinate noble gas atoms in forming noble gas complexes. The results showed that VO2 coordinates two Ar or Xe atoms and that VO4 coordinates one Ar or Xe atom in solid noble gas matrixes. Hence, the VO2 and VO4 molecules trapped in solid noble gas matrixes should be regarded as the VO2(Ng)2 and VO4(Ng) (Ng = Ar or Xe) complexes. The total V-Ng binding energies were predicted to be 12.8, 18.2, 5.0, and 7.3 kcal/mol, respectively, for the VO2(Ar)2, VO2(Xe)2, VO4(Ar), and VO4(Xe) complexes at the CCSD(T)//B3LYP level of theory. PMID:16451016

  7. Process gases for laser welding

    Microsoft Academic Search

    Mark Faerber; Joachim Berkmann

    1997-01-01

    To achieve a high return on investment, laser systems must be used to their fullest capacity, avoiding power losses and downtimes. High-quality laser gases are therefore needed to run the laser. But if the quality of the gas cannot be guaranteed all the way from the cylinder to the laser cavity, the risk of impurities such as water vapor and

  8. Understanding the adsorption mechanism of noble gases Kr and Xe in CPO-27-Ni, CPO-27-Mg, and ZIF-8.

    PubMed

    Magdysyuk, O V; Adams, F; Liermann, H-P; Spanopoulos, I; Trikalitis, P N; Hirscher, M; Morris, R E; Duncan, M J; McCormick, L J; Dinnebier, R E

    2014-11-21

    An experimental study of Xe and Kr adsorption in metal-organic frameworks CPO-27-Ni, CPO-27-Mg, and ZIF-8 was carried out. In situ synchrotron X-ray powder diffraction experiments allowed precise determination of the adsorption sites and sequence of their filling with increasing of gas pressure at different temperatures. Structural investigations were used for interpretation of gas adsorption measurements. PMID:25277596

  9. PII S0016-7037(01)00804-3 A paleotemperature record derived from dissolved noble gases in groundwater of the

    E-print Network

    Aeschbach-Hertig, Werner

    . This difference is slightly lower than estimates derived from pollen data for this region, but considerably larger. In the tropics, continental proxies such as snow- lines, pollen (Colinvaux et al., 1996), oxygen isotopes in gla- MAP, 1976, 1981), although the discrepancy has been some- what diminished by reassessments

  10. Low field magnetic resonance images of polarized noble gases obtained with a dc superconducting quantum interference device

    SciTech Connect

    Augustine, M.P.; Wong-Foy, A.; Yarger, J.L.; Tomaselli, M.; Pines, A. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720] [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720; [Department of Chemistry, University of California, Berkeley, California94720 (United States); TonThat, D.M.; Clarke, J. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720] [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720; [Department of Physics, University of California, Berkeley, California94720 (United States)

    1998-04-01

    Using a low transition temperature superconducting quantum interference device as a detector, we have obtained magnetic resonance images of laser-polarized {sup 3}He gas and solid {sup 129}Xe at 4.2 K in magnetic fields as low as 0.54 mT ({sup 3}He) and 1 mT ({sup 129}Xe), corresponding to Larmor frequencies of 17.6 and 11.8 kHz, respectively. The experimental resolution of the images is {approximately}500{mu}m for {sup 3}He in the gas phase and {approximately}950{mu}m for {sup 129}Xe in the solid state. {copyright} {ital 1998 American Institute of Physics.}

  11. 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 ...

  12. 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.

  13. Tracer Applications of Noble Gas Radionuclides in the Geosciences

    E-print Network

    Lu, Z -T; Smethie, W M; Sturchio, N C; Fischer, T P; Kennedy, B M; Purtschert, R; Severinghaus, J P; Solomon, D K; Tanhua, T; Yokochi, R

    2013-01-01

    The noble gas radionuclides, including 81Kr (half-life = 229,000 yr), 85Kr (11 yr), and 39Ar (269 yr), possess nearly ideal chemical and physical properties for studies of earth and environmental processes. Recent advances in Atom Trap Trace Analysis (ATTA), a laser-based atom counting method, have enabled routine measurements of the radiokrypton isotopes, as well as the demonstration of the ability to measure 39Ar in environmental samples. Here we provide an overview of the ATTA technique, and a survey of recent progress made in several laboratories worldwide. We review the application of noble gas radionuclides in the geosciences and discuss how ATTA can help advance these fields, specifically determination of groundwater residence times using 81Kr, 85Kr, and 39Ar; dating old glacial ice using 81Kr; and an 39Ar survey of the main water masses of the oceans, to study circulation pathways and estimate mean residence times. Other scientific questions involving deeper circulation of fluids in the Earth's crust ...

  14. Noble metal-free hydrogen evolution catalysts for water splitting.

    PubMed

    Zou, Xiaoxin; Zhang, Yu

    2015-08-01

    Sustainable hydrogen production is an essential prerequisite of a future hydrogen economy. Water electrolysis driven by renewable resource-derived electricity and direct solar-to-hydrogen conversion based on photochemical and photoelectrochemical water splitting are promising pathways for sustainable hydrogen production. All these techniques require, among many things, highly active noble metal-free hydrogen evolution catalysts to make the water splitting process more energy-efficient and economical. In this review, we highlight the recent research efforts toward the synthesis of noble metal-free electrocatalysts, especially at the nanoscale, and their catalytic properties for the hydrogen evolution reaction (HER). We review several important kinds of heterogeneous non-precious metal electrocatalysts, including metal sulfides, metal selenides, metal carbides, metal nitrides, metal phosphides, and heteroatom-doped nanocarbons. In the discussion, emphasis is given to the synthetic methods of these HER electrocatalysts, the strategies of performance improvement, and the structure/composition-catalytic activity relationship. We also summarize some important examples showing that non-Pt HER electrocatalysts could serve as efficient cocatalysts for promoting direct solar-to-hydrogen conversion in both photochemical and photoelectrochemical water splitting systems, when combined with suitable semiconductor photocatalysts. PMID:25886650

  15. 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

  16. JOURNAL DE PHYSIQUE Colloque C1, supplbment au nOl,Tome 46, janvier 1985 page C1-26 1

    E-print Network

    Paris-Sud XI, Université de

    OF STABLE AND RADIOACTIVE NOBLE GAS NUCLEI BY S P I N EXCHANGE WITH LASER PUMPED ALKALI ATOMS W. Happer angular momentum of t h e a l k a l i atoms is transferred t o t h e nulcear spin of t h e noble gas. Most and noble gas atoms about each other. For heavy noble gases most of t h e angular momentum t r a n s f e r

  17. 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.

  18. Chemistry of Carbon Gases in Volcanic Gases on Io

    NASA Astrophysics Data System (ADS)

    Schaefer, L.; Fegley, B., Jr.

    2004-11-01

    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 K, P = 0.01 bar, and O/S ˜ 1.5. Bulk C/S atomic ratios ranging from 10-4 to 10-1 are used in the equilibrium calculations, with a nominal value of 10-3 based upon upper limits for carbon on Io from Voyager observations of the Loki plume. Carbon monoxide and CO2 are the two major carbon gases under nearly all conditions studied. Carbonyl sulfide and CS2 are orders of magnitude less abundant. Consideration of different loss processes including photolysis, condensation, and kinetic reactions in the plume indicates that photolysis is probably the major loss process for all gases. Both CO and CO2 should be observable in volcanic plumes and in Io's atmosphere at abundances of several hundred parts per million by volume for a bulk C/S atomic ratio of 10-3. This work is supported by the NASA Planetary Atmospheres program.

  19. Efficient conversion of 3He(n,tp) and 10B(n, ?7Li) reaction energies into far-ultraviolet radiation by noble gas excimers

    NASA Astrophysics Data System (ADS)

    Hughes, Patrick P.; Coplan, Michael A.; Thompson, Alan K.; Vest, Robert E.; Clark, Charles W.

    2011-03-01

    Previous work showed that the 3He(n , tp) reaction in a cell of 3He at atmospheric pressure generated tens of far-ultraviolet (FUV) photons per reacted neutron. Here we report amplification of that signal by factors of 1000 when noble gases are added to the cell. Calibrated filter-detector measurements show that this large signal is due to noble-gas excimer emissions, and that the nuclear reaction energy is converted to FUV radiation with efficiencies of up to 30 % . Our results have been placed on an absolute scale through calibrations at the NIST SURF III Synchrotron and Center for Neutron Research. We have also seen large neutron-induced FUV signals when the 3He gas in our system is replaced with a 10B film target; an experiment on substituting 3He with BF3 is underway. Our results suggest possibilities for high-efficiency, non-3He neutron detectors as an alternative to existing proportional counters.

  20. 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...

  1. Catalyst for purifying exhaust gases

    SciTech Connect

    Fujitani, Y.; Kondoh, S.; Muraki, H.; Nakamura, T.; Sobukawa, H.; Tomita, M.; Yokota, K.

    1982-02-23

    A catalyst for reducing nitrogen oxides, carbon monoxide and hydrocarbons, the noxious components in exhaust gases from internal combustion engines, etc., is disclosed comprising: a porous carrier of ceramic selected from the group consisting of alumina and alumina-magnesia spinel; and a catalyst ingredient supported thereon consisting essentially of zirconium oxide, cerium oxide and a metal selected from the group consisting of platinum, palladium and mixtures thereof.

  2. Thermomagnetic Force in Polyatomic Gases 

    E-print Network

    Larchez, M. E.; Adair, Thomas W.

    1971-01-01

    . Since then extensive investigations have been conducted on these field effects [now called Senftleben-Beenakker (SB}effects] in nu- merous gases. A comprehensive review and bib- liography of the experimental and theoretical work in this field can... in place were identical to those made without it. IV. DISCUSSION OF RESULTS The thermomagnetic-force effect reported here may be compared to the Senftleben-Beenakker (SB) effect. The force effect approaches a maxi- mum as a universal function of H...

  3. Boosting Terahertz Generation in Laser-Field Ionized Gases Using a Sawtooth Wave Shape

    NASA Astrophysics Data System (ADS)

    Martínez, P. González de Alaiza; Babushkin, I.; Bergé, L.; Skupin, S.; Cabrera-Granado, E.; Köhler, C.; Morgner, U.; Husakou, A.; Herrmann, J.

    2015-05-01

    Broadband ultrashort terahertz (THz) pulses can be produced using plasma generation in a noble gas ionized by femtosecond two-color pulses. Here we demonstrate that, by using multiple-frequency laser pulses, one can obtain a waveform which optimizes the free electron trajectories in such a way that they acquire the largest drift velocity. This allows us to increase the THz conversion efficiency to 2%, an unprecedented performance for THz generation in gases. In addition to the analytical study of THz generation using a local current model, we perform comprehensive 3D simulations accounting for propagation effects which confirm this prediction. Our results show that THz conversion via tunnel ionization can be greatly improved with well-designed multicolor pulses.

  4. High Pressure Gases in Hollow Core Photonic Crystal Fiber:A New Nonlinear Medium

    E-print Network

    Azhar, Mohiudeen; Chang, Wonkeun; Joly, Nicolas; Russell, Philip

    2012-01-01

    The effective Kerr nonlinearity of hollow-core kagome-style photonic crystal fiber (PCF) filled with argon gas increases over 100 times when the pressure is increased from 1 to 150 bar, reaching 15 % of that of bulk silica glass, while the zero dispersion wavelength shifts from 300 to 900 nm. The group velocity dispersion of the system is uniquely pressure-tunable over a wide range while avoiding Raman scattering : absent in noble gases and having an extremely high optical damage threshold. As a result, detailed and well controlled studies of nonlinear effects can be performed, in both normal and anomalous dispersion regimes, using only a fixed-frequency pump laser. For example, the absence of Raman scattering permits clean observation, at high powers, of the interaction between a modulational instability side-band and a soliton created dispersive wave. Excellent agreement is obtained between numerical simulations and experimental results. The system has great potential for the realisation of reconfigurable s...

  5. 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.

  6. Surface entropy of liquid transition and noble metals

    NASA Astrophysics Data System (ADS)

    Gosh, R. C.; Das, Ramprosad; Sen, Sumon C.; Bhuiyan, G. M.

    2015-07-01

    Surface entropy of liquid transition and noble metals has been investigated using an expression obtained from the hard-sphere (HS) theory of liquid. The expression is developed from the Mayer's extended surface tension formula [Journal of Non-Crystalline Solids 380 (2013) 42-47]. For interionic interaction in metals, Brettonet-Silbert (BS) pseudopotentials and embedded atom method (EAM) potentials have been used. The liquid structure is described by the variational modified hypernetted chain (VMHNC) theory. The essential ingredient of the expression is the temperature dependent effective HS diameter (or packing fraction), which is calculated from the aforementioned potentials together with the VMHNC theory. The obtained results for the surface entropy using the effective HS diameter are found to be good in agreement with the available experimental as well as other theoretical values.

  7. DARWIN: dark matter WIMP search with noble liquids

    E-print Network

    Laura Baudis; for the DARWIN Consortium

    2012-01-11

    DARWIN (dark matter wimp search with noble liquids) is a design study for a next-generation, multi-ton dark matter detector in Europe. Liquid argon and/or liquid xenon are the target media for the direct detection of dark matter candidates in the form of weakly interacting massive particles (WIMPs). Light and charge signals created by particle interactions in the active detector volume are observed via the time projection chamber technique. DARWIN is to probe the spin-independent, WIMP-nucleon cross section down 1e-48 cm2 and to measure WIMP-induced nuclear recoil spectra with high-statistics, should they be discovered by an existing or near-future experiment. After a brief introduction, I will describe the project, selected R&D topics, expected backgrounds and the physics reach.

  8. DARWIN: dark matter WIMP search with noble liquids

    E-print Network

    Laura Baudis

    2010-12-21

    DARWIN (DARk matter WImp search with Noble liquids) is an R&D and design study towards the realization of a multi-ton scale dark matter search facility in Europe, based on the liquid argon and liquid xenon time projection chamber techniques. Approved by ASPERA in late 2009, DARWIN brings together several European and US groups working on the existing ArDM, XENON and WARP experiments with the goal of providing a technical design report for the facility by early 2013. DARWIN will be designed to probe the spin-independent WIMP-nucleon cross section region below 10-47cm^2 and to provide a high-statistics measurement of WIMP interactions in case of a positive detection in the intervening years. After a brief introduction, the DARWIN goals, components, as well as its expected physics reach will be presented.

  9. Noble-metal nanostructures on carburized W(110)

    PubMed Central

    Bachmann, Magdalena; Memmel, Norbert; Bertel, Erminald

    2011-01-01

    Noble metal nanostructures of Au, Ag and Cu were prepared on two types of carbon-modified W(110) surfaces—R(15 × 12) and R(15 × 3)—and investigated by means of scanning tunneling microscopy. For all deposited metals qualitatively the same behaviour is observed: On the R(15 × 12)-template always isotropic clusters are formed. In contrast, on the R(15 × 3)-substrate the anisotropy of the nanostructures can be tuned from clusters at low temperatures via thin nanowires to thicker nanobars at high deposition temperatures. At intermediate temperatures on the R(15 × 3) the anisotropic Au nanowires arrange themselves into straight lines along domain boundaries induced by deposition of the Au metal. Similarities and differences to Au nanostructures as recently reported by Varykhalov et al. [A. Varykhalov, O. Rader, W. Gudat. Physical Review B 77, 035412 (2008).] are discussed. PMID:21779133

  10. 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

  11. Excitation of the t bar ( n +1) sup 3 P sub 2 r angle and t bar ( n +1) sup 3 P sub 0 r angle metastable levels of the heavy rare gases from the t bar n sup 1 S sub 0 r angle ground state by electron impact

    SciTech Connect

    Khakoo, M.A.; Tran, T.; Bordelon, D. (Physics Department, California State University, Fullerton, California 92634 (United States)); Csanak, G. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))

    1992-01-01

    Relative intensity ratios for the differential electron-impact excitation of the metastable states of the rare gases neon, argon, and xenon at the incident energy of 30 eV and scattering angles 10{degree}--120{degree} are presented and are compared with available theory.

  12. Process gases for laser welding

    NASA Astrophysics Data System (ADS)

    Faerber, Mark; Berkmann, Joachim

    1997-08-01

    To achieve a high return on investment, laser systems must be used to their fullest capacity, avoiding power losses and downtimes. High-quality laser gases are therefore needed to run the laser. But if the quality of the gas cannot be guaranteed all the way from the cylinder to the laser cavity, the risk of impurities such as water vapor and hydrocarbons or particles entering the laser system is large. Unstable laser operation and damage to the resonator optics can result in costly repairs. The profitability of laser operations is also affected by the selection of the assist gas. High-purity oxygen and high-pressure high-purity nitrogen are frequently used to optimize the productivity of laser cutting. In contrast, different assist gases are used for laser welding depending on the wavelength of the laser radiation, the material, the energy per unit length of weld or the assist gas nozzle arrangement. Helium is often the most convenient choice for CO2 laser welding of mild steel, resulting in optimum seam quality with respect to formability and appearance. Helium-argon mixtures can be used effectively for lower power CO2 laser welding and for aluminum. Nitrogen mixtures may be used to stabilize the austenitic phase in duplex steels whereas hydrogen additions give a shiny bead surface in stainless steel. Argon is suitable for Nd:YAG laser welding and productivity is increased by small additions of oxygen. In addition argon- CO2 mixtures may be used to achieve acceptable results depending on the assist gas nozzle arrangement. Consequently, high-purity gases and suitable gas distribution equipment are the basis for a satisfactory return on investment.

  13. Noble Gas-Actinide Compounds: Complexation of the CUO Molecule by Ar, Kr, and Xe Atoms in Noble Gas Matrices

    SciTech Connect

    Li, Jun; Bursten, Bruce E.; Liang, Binyong; Andrews, Lester

    2002-03-22

    The CUO molecule, formed from the reaction of laser-ablated U atoms with CO in a noble gas, exhibits very different stretching frequencies in a solid argon matrix (804.3 and 852.5 cm -1 ) than in a solid neon matrix (872.2 and 1047.3 cm -1 ). Related experiments in a matrix consisting of 1% Ar in Ne suggest that the Ar atoms are interacting directly with the CUO molecule. Relativistic density functional calculations predict that CUO can bind directly to an Ar atom (U-Ar= 3.16 angstroms; binding energy= 3.2 kcal/mol), accompanied by a change in the ground state from a singlet to a triplet. The experimental and theoretical results suggest the possibility that multiple Ar atoms can bind to a single CUO molecule.

  14. Noble gas-actinide compounds: complexation of the CUO molecule by Ar, Kr, and Xe atoms in noble gas matrices.

    PubMed

    Li, Jun; Bursten, Bruce E; Liang, Binyong; Andrews, Lester

    2002-03-22

    The CUO molecule, formed from the reaction of laser-ablated U atoms with CO in a noble gas, exhibits very different stretching frequencies in a solid argon matrix [804.3 and 852.5 wave numbers (cm(-1))] than in a solid neon matrix (872.2 and 1047.3 cm(-1)). Related experiments in a matrix consisting of 1% argon in neon suggest that the argon atoms are interacting directly with the CUO molecule. Relativistic density functional calculations predict that CUO can bind directly to one argon atom (U-Ar = 3.16 angstroms; binding energy = 3.2 kilocalories per mole), accompanied by a change in the ground state from a singlet to a triplet. Our experimental and theoretical results also suggest that multiple argon atoms can bind to a single CUO molecule. PMID:11872801

  15. The origin of hydrothermal and other gases in the Kenya Rift Valley

    SciTech Connect

    Darling, W.G. [British Geological Survey, Wallingford (United Kingdom)] [British Geological Survey, Wallingford (United Kingdom); Griesshaber, E. [Max-Planck Institut fuer Chemie, Mainz (Germany)] [Max-Planck Institut fuer Chemie, Mainz (Germany); Andrews, J.N. [Univ. of Reading (United Kingdom)] [and others] [Univ. of Reading (United Kingdom); and others

    1995-06-01

    The Kenya Rift Valley (KRV) is part of a major continental rift system from which much outgassing is presently occurring. Previous research on gases in the KRV has tended to concentrate on their geothermal implications; the present paper is an attempt to broaden the interpretation by consideration of new data including helium and carbon isotope analyses from a wide cross-section of sites. In order to do this, gases have been divided into categories dependent on origin. N{sub 2} and noble gases are for the most part atmospherically derived, although their relative concentrations may be altered from ASW ratios by various physical processes. Reduced carbon (CH{sub 4} and homologues) appears to be exclusively derived from the shallow crust, with thermogenic {delta}{sup 13}C values averaging -25{per_thousand} PDB for CH{sub 4}. H{sub 2} is likely also to be crustally formed. CO{sub 2}, generally a dominant constituent, has a narrow {delta}{sup 13}C range averaging -3.7{per_thousand} PDB, and is likely to be derived with little modification from the upper mantle. Consideration of the ratio C/{sup 3}He supports this view in most cases. Sulphur probably also originates there. Ratios of {sup 3}He/{sup 4}He reach a MORB-like maximum of 8.0 R/R{sub A} and provide the best indication of an upper mantle source of gases beneath the KRV. A correlation between {sup 3}He/{sup 4}He and the hydrocarbon parameter log (C{sub 1}/{Sigma}C{sub 2-4}) appears to be primarily temperature related. The highest {sup 3}He/{sup 4}He ratios in spring waters are associated with basalts, perhaps because of the leaching of basalt glasses. There may be a structural control on {sup 3}He/{sup 4}He ratios in the KRV as a whole.

  16. 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.

  17. Determination of noble metals in Savannah River Site high-level radioactive sludge

    SciTech Connect

    Coleman, C.J.; Kinard, W.F.; Bibler, N.E.; Bickford, D.F.; Ramsey, W.G.

    1990-12-31

    High-level radioactive sludge at the Savannah River Site (SRS) will be processed at the Defense Waste Processing Facility (DWPF) into durable borosilicate glass wasteforms. The sludges are analyzed for elemental content before processing to ensure compatibility with the glass-making processes. Noble metal fission products in sludge, can under certain conditions, cause problems in the glass melter. Therefore, reliable noble metal determinations are important. The scheme used to measure noble metals in SRS sludges consists of dissolving sludge with hot aqua regia followed by determinations with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and ICP-Mass Spectroscopy (ICP-MS) techniques. ICP-MS is the preferred method for measuring trace levels of noble metals in SRS radioactive waste because of superior sensitivity. Analytical results are presented for the two major types of SRS sludge.

  18. Determination of noble metals in Savannah River Site high-level radioactive sludge

    SciTech Connect

    Coleman, C.J.; Kinard, W.F.; Bibler, N.E.; Bickford, D.F.; Ramsey, W.G.

    1990-01-01

    High-level radioactive sludge at the Savannah River Site (SRS) will be processed at the Defense Waste Processing Facility (DWPF) into durable borosilicate glass wasteforms. The sludges are analyzed for elemental content before processing to ensure compatibility with the glass-making processes. Noble metal fission products in sludge, can under certain conditions, cause problems in the glass melter. Therefore, reliable noble metal determinations are important. The scheme used to measure noble metals in SRS sludges consists of dissolving sludge with hot aqua regia followed by determinations with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and ICP-Mass Spectroscopy (ICP-MS) techniques. ICP-MS is the preferred method for measuring trace levels of noble metals in SRS radioactive waste because of superior sensitivity. Analytical results are presented for the two major types of SRS sludge.

  19. The surface modification of fluorine-doped tin oxide by the underpotential deposition of noble metals

    SciTech Connect

    Colton, R.H.; Hager, H.E.

    1986-12-01

    The surface modification of fluorine-doped tin oxide by the underpotential deposition of noble metals (Rh, Ru, Pd, Pt, and Au) strongly influences the rate of sulfide-polysulfide reduction at the SnO/sub 2/ electrode. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy are used to characterize as-prepared and surface modified tin oxide preceding and following electrode operation. The noble metal coverages follow the relative ordering: Au, Pt < Ru, Pd < Rh, showing an identical trend as the observed enhancement effects. Depth profile analysis shows that rhodium is found more than 100A into the tin oxide film. This spatial distribution is apparently an artifact of the columnar SnO/sub 2/ structure. The XPS atom bonding peaks for the noble metals are shifted from the peak values associated with metallic states by an amount which is dependent on the exposure history of the tin oxide and yet independent of the noble metal species.

  20. 75 FR 12737 - Applications To Export Electric Energy; Noble Energy Marketing and Trade Corp.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-17

    ...EA-364] Applications To Export Electric Energy; Noble Energy Marketing and...applied for authority to transmit electric energy from the United States to Mexico...NEMT for authority to transmit electric energy from the United States to...