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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, 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.

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

    DOEpatents

    Gross, Kenneth C.; Markun, Francis; Zawadzki, Mary T.

    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.

  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, metaphorically a drop in the bucket. Thus, they are very difficult or impossible to detect and, therefore, in practical terms, attracting little or no interest. When the bucket is empty, or nearly so, however, the "drop" contributed by nuclear transmutations may become observable or even dominant. Traditionally there are two types of (nearly) empty buckets that are most suitable for revealing the effects of nuclear transmutations: short-lived radionuclides (e.g., 10Be and 26Al) which would be entirely absent except for recent nuclear reactions, and the noble gases, renowned for their scarcity.Emphasis on nuclear processes explains what sometimes seems to be an obsession with isotopes in noble-gas geo- and cosmochemistry. Different nuclear processes will produce different isotopes, singly or in suites with well-defined proportions (i.e., "components"), different from one process to another. Much of the traditional agenda of noble-gas geochemistry, and especially cosmochemistry, thus consists of isotopic analysis, and deconvolution of an observed isotopic spectrum into constituent components. (In most geochemical investigations, noble gases are detected by mass spectrometry, a technique that is inherently sensitive to specific isotopes, not just the chemical element. Isotopic data thus emerge naturally in most studies. Noble-gas mass spectrometry can be a much more sensitive technique than other traditional types of mass spectrometry because the gases are "noble," and therefore relatively easy to separate from other elements, and because they are scarce, so that they can be analyzed in "static"-mode (no pumping during analysis) gas-source spectrometers, permitting relatively high detection efficiency without overwhelming blanks.) In realistic terms, it is very difficult to appreciate noble-gas geo-/cosmochemistry without a basic familiarity with noble-gas isotopes: which isotopes occur in nature (i.e., which are stable), in what approximate abundance they are found, how they relate to non-noble neighbors, and, to some extent, how they are associated with specific nuclear processes. Figure 1 provides assistance in this regard. (6K)Figure 1. A display of the isotopes of the noble gases and neighboring isotopes in the familiar "chart of the nuclides" format. The abscissa is neutron number (N) and the ordinate is proton number (Z). The box corresponding to any pair (Z, N) represents an isotope; an element is represented by a horizontal row. Boxes for stable isotopes are shown with solid outline; for the noble gases, approximate solar (in the case of He, protosolar) isotope ratios are shown at the bottom of each box. Selected unstable isotopes are shown as boxes with broken line edges. The left-superscript isotope label is the atomic weight A (=Z+N). The five panels show regions around the five noble gases (excluding Rn). When the goal is to identify and quantify different noble-gas components that may be present in a sample or group of samples, a common approach to this goal is to try to unmix the components, at least partially, to provide some leverage. One path to this end, of course, is analysis of different samples that may contain the components in different proportions, and thus have different isotopic compositions. Another path, available in addition to or instead of the first, is stepwise heating analysis, which has traditionally been very extensively used in noble-gas studies. Noble gases may be released from solid samples by volume diffusion, or by reaction, recrystallization, melting, or even evaporation of their host phases. If different noble-gas components reside in physically distinct locations within a complex sample, they may be liberated, and thus become available for analysis, at different steps in a time-temperature heating sequence. Differential release of isotopically distinct components will then result in variation of the isotopic composition of gas released in different steps (e.g., see Figures 2 and 4). (12K)Figure 2. A three-isotope diagram illustrating compositional variations in lunar samples and meteorites, as observed in stepwise in vacuo etching and pyrolysis. Since the observed isotopic compositions do not lie on a single straight line, at least three isotopically distinct components must contribute in variable proportions. These data are interpreted as superposition of solar wind (SW), solar energetic particles (SEP), and galactic cosmic ray, i.e., spallation (GCR) Ne components (source Wieler, 1998). A common tool for visualization of isotopic variations is the so-called "three-isotope diagram," in which two isotope ratios, each with the same reference (denominator) isotope, are displayed on abscissa and ordinate (e.g., Figure 2). Two isotopically distinct components will plot at distinct points on a three-isotope diagram, and an often-used feature is that mixtures of the two components will plot on the straight line joining those two points. A lever rule applies: the greater the proportion that one component contributes to a mixture, the closer the point representing the mixture will lie to the point representing that end-member component, and there is a linear relationship between fractional distance from one end-member to the other and the fraction that each component contributes to the mixture (specifically to the reference isotope). If observed isotopic data are variable but the variations in two ratios are correlated, so as to be consistent with a straight line on a three-isotope diagram, it can be inferred that at least two components are present and it will often be hypothesized that only two components are present, in which case their compositions can be constrained to lie on the line, one on either side of the data field. If three components are present, not coincidentally collinear on this diagram, mixtures will occupy the triangular field defined by the three compositions, and conversely if observed data are not consistent with linear correlation it can be inferred that at least three components are contributing to the mix. The concept of the three-isotope diagram is readily generalized. Four isotopes defining three ratios (all with the same reference isotope), for example, will define a three-dimensional space in which mixture of two components will produce compositions lying along a straight line, and mixture of three components will produce compositions lying in a plane, etc. Generalization to more dimensions is mathematically straightforward, even if difficult to envision.

  5. Rubidium D1 collision shift by heavy noble gases

    NASA Astrophysics Data System (ADS)

    Wells, N. P.; Driskell, T. U.; Camparo, J. C.

    2015-10-01

    Using an isoclinic-point technique, we measured the D1 collision shift by Xe, ∂ [δ ν ]/∂ P , and the exponent κ of the shift's temperature dependence (i.e., δ ν ˜Tκ ). As demonstrated in our examination of the Rb-Kr system [N. P. Wells et al., Phys. Rev. A 89, 052516 (2014), 10.1103/PhysRevA.89.052516], the isoclinic point provides (arguably) the only means of assessing κ unambiguously: κKr=0.36 ±0.06 and in the present work κXe=0.32 ±0.05 . With our estimate of κ for the Rb-Kr and Rb-Xe systems, we were able to combine our Kr and Xe collision shift measurements with those of Rotondaro and Perram [M. D. Rotondaro and G. P. Perram, J. Quant. Spectrosc. Radiat. Transfer 57, 497 (1997), 10.1016/S0022-4073(96)00147-1] (another set of high quality ∂ [δ ν ]/∂ P measurements) to obtain a highly accurate experimental estimate for the D1 collision shift resulting from Rb's interaction with the heavy noble gases: For the Rb-Kr interaction ∂ [δ ν ] /∂ P |T =323 K=-5.02 ±0.07 MHz /torr and for the Rb-Xe interaction ∂ [δ ν ] /∂ P |T =323 K=-5.46 ±0.09 MHz /torr . These measured values for the collision-shift coefficient are approximately 20 % smaller (in magnitude) than the best theoretical estimates, suggesting that there is room for theoretical improvement regarding our present understanding of how noble-gas collisions perturb the alkali-metal P1 /2 state.

  6. Planetary noble gases

    NASA Technical Reports Server (NTRS)

    Zahnle, Kevin

    1993-01-01

    An overview of the history and current status of research on planetary noble gases is presented. The discovery that neon and argon are vastly more abundant on Venus than on earth points to the solar wind rather than condensation as the fundamental process for placing noble gases in the atmospheres of the terrestrial planets; however, solar wind implantation may not be able to fully reproduce the observed gradient, nor does it obviously account for similar planetary Ne/Ar ratios and dissimilar planetary Ar/Kr ratios. More recent studies have emphasized escape rather than accretion. Hydrodynamic escape, which is fractionating, readily accounts for the difference between atmospheric neon and isotopically light mantle neon. Atmospheric cratering, which is nearly nonfractionating, can account for the extreme scarcity of nonradiogenic noble gases (and other volatiles) on Mars.

  7. The viscosity cross section for electron scattering from the heavy noble gases

    NASA Astrophysics Data System (ADS)

    Stauffer, Allan; McEachran, Robert

    2014-10-01

    The viscosity cross section is defined in terms of the elastic differential cross section σ (θ) as σv =∫0 π (1 -cos2 θ) sin θ σ (θ) dθ and appears in the Boltzmann equation for the electron distribution function in velocity space. If this distribution function is expanded in Legendre polynomials, the viscosity cross section arises from the third term. Normally, only the first two terms in this expansion are retained in the solution of the Boltzmann equation. We have recently published results for the elastic and momentum transfer cross section for electron scattering from the heavy noble gases (argon, krypton and xenon) using our complex, relativistic optical potential method which includes the effect of excitation and ionization channels on the elastic cross sections. We also provided simple analytic fits to these cross sections to aid in plasma modelling calculations. We will present similar results for the viscosity cross sections for these gases including fits using similar analytic functions. By including the third term in the expansion of the Boltzmann equation which depends on this cross section, an evaluation of the accuracy of the two-term solution can be made.

  8. Noble Gas Systematics in MORBs and OIBs and Reconstitution of the Time-Evolution of Mantle Composition for Heavy Noble Gases: the Role of Subduction of Atmospheric Noble Gases.

    NASA Astrophysics Data System (ADS)

    Roubinet, C.; Moreira, M. A.

    2014-12-01

    Chondrites are considered as the building rocks of the Earth as they represent remnants of the protoplanetary accretion stage. Among all chondritic classes, heavy noble gases are mainly concentrated in phase Q [1] hence it represents a likely primordial composition of the Earth. This is supported by the observation of [2] who detected this peculiar composition in CO2 well gases thanks to Kr isotopes. As CO2 well gases are supposed to derive from the same reservoir as MORBs [3], this signature should be observed in MORBs and OIBs as well. In this perspective, we will present analyses performed by mass spectrometry of MORBs and OIBs samples for all noble gases. Preliminary results are quite promising as the same trend seems to appear into OIB and MORB data for Kr isotopes. However, our analyses show that this primordial composition isn't displayed for stable isotopes of Xe as already observed by [4-5] and remains a trace in the mantle signature, which appears at first sight atmospheric. We thus propose that subduction of atmospheric noble gases has gradually covered this meteoritic imprint. In order to test this scenario, we will present a modelling performed for Ar and Xe in three distinct reservoirs: mantle, atmosphere and continental crust. The mantle is considered as homogenized by convection and similar to the MORB reservoir. Its degasing is divided in two stages: a massive early degasing followed by a decreasing one describing the cooling of the Earth's interior. Extraction of parent elements from the mantle to the continental crust is also taken into account as well as distillation of atmospheric Xe needed to explain the missing Xe paradox and the present Xe isotopic signature of the atmosphere. Finally, subduction of noble gases is assimilated to simple incorporation into the mantle of elementally fractionated air, enriched in heavy noble gases as supported by [6]. Thus, we show that starting with a chondritic composition, the present mantle composition can be reproduced and that subduction plays a major role as it explains the nearly atmospheric signature of the mantle for Xe stable isotopes and considerably lowers the radiogenic isotopic ratios. [1] Huss et al., GCA (1996) [2] Holland et al., Sci. (2009) [3] Staudacher, Nat. (1987) [4] Kunz et al., Sci. (1998) [5] Trieloff et al., Sci. (2000) [6] Kendrick et al., Nat. Geo. (2011)

  9. 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; Schmitt, Bernard

    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.

  10. Holographic interferometry study of two-fluid properties of the plasma in current sheets formed in heavy noble gases

    SciTech Connect

    Bogdanov, S. Yu.; Dreiden, G. V.; Markov, V. S.; Ostrovskaya, G. V.; Frank, A. G.

    2007-11-15

    Two-exposure holographic interferometry was used to study the structure of current sheets formed in three-dimensional magnetic configurations with a singular X line in heavy noble gases (Ar, Kr, and Xe). It is found that, in the presence of a longitudinal magnetic field B{sub Z} directed along the X line, plasma sheets take on an unusual shape: they are titled and asymmetric. Their asymmetry becomes more pronounced as the mass of a plasma ion increases-a manifestation of the two-fluid properties of the plasma. The observed effects can be attributed to additional forces arising due to the interaction of the longitudinal magnetic field B{sub Z} with Hall currents excited in a plane perpendicular to the X line. A qualitative model describing plasma dynamics with allowance for the Hall effect and accounting for most of the experimentally observed effects is proposed.

  11. Noble Gases as Mantle Tracers

    NASA Astrophysics Data System (ADS)

    Hilton, D. R.; Porcelli, D.

    2003-12-01

    The study of the noble gases has been associated with some of the most illustrious names in experimental science, and some of the most profound discoveries. Fundamental advances in nuclear chemistry and physics - including the discovery of isotopes - have resulted from their study, earning Nobel Prizes for a number of early practitioners (Rutherford in 1908; Soddy in 1921; Aston in 1922) as well as for their discoverers (Ramsay and Rayleigh in 1904). Within the Earth Sciences, the noble gases found application soon after discovery - helium was used as a chronometer to estimate formation ages of various minerals (Strutt, 1908). In more recent times, the emphasis of noble gas research has shifted to include their exploitation as inert tracers of geochemical processes. In large part, this shift stems from the realization that primordial volatiles have been stored within the Earth since the time of planetary accretion and are still leaking to the surface today. In this introduction, we give a brief overview of the discovery of the noble gases and their continuing utility in the Earth Sciences, prior to setting into perspective the present contribution, which focuses on noble gases in the Earth's mantle.

  12. Light Collection in Liquid Noble Gases

    SciTech Connect

    McKinsey, Dan

    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.

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

    NASA Astrophysics Data System (ADS)

    Thonnard, N.

    1995-09-01

    Since the first reliable indication of the existence of non-terrestrial composition of Xe isotopes in meteorites by Reynolds [1,2], anomalies have been found in the isotopic composition of many elements in meteorites, implying a plurality of nucleosynthetic processes, and indicating that the initial conditions leading to the formation of the solar system were quite diverse [3]. Noble gases provide a unique window into the composition of the progenitor material to the solar system [4]. Stellar evolution may contribute by the s-process, r-process, p-process, etc., each with its own isotopic distribution. Kr and Xe are especially useful as the large number of isotopes (7 in the 78Kr to 86Kr range, and 9 in the 124Xe to 136Xe range) provide many clues to help unravel the multiple sources to the measured abundances. Although Xe has been measured and analyzed considerably more frequently than Kr in meteorite studies, this has only partially been due to the wealth of information derivable from Xe studies, but also, due to experimental difficulties encountered in Kr measurements. Early in the development of stellar nucleosynthesis, 86Kr was proposed as a chronometer of the s-process [5], but until recently has provided unreliable results [6]. Other interesting properties derivable from Kr isotope measurements include 78Kr as an indication of spallation history, 80Kr as a stellar thermometer, and 81Kr and 83Kr to determine cosmic ray exposure ages. Studies of highly refractory microscopic grains (diamond, graphite and SiC) separated from the much more abundant carbonaceous matrix in primitive meteorites have shown a remarkable isotopic composition diversity in a small fraction of single grains from the same meteorite, implying multiple stellar sources [4]. Ion microprobe measurements have been possible of the major constituents of single interstellar grains [7,8] and of He and Ne using a state-of-the-art static noble gas mass spectrometer [9-11]. But, a recent attempt to measure noble gases from fourteen individual "X" SiC grains, previously identified by ion microprobe analysis, was unsuccessful with the 2,000 132Xe atom detection limit of the mass spectrometer [12,13]. From the Kr concentration measurements of SiC particles KJF by Lewis et al. [6], a 2 micrometer diameter particle will on average contain 134 Kr atoms. If only 4% of the SiC grains contain the majority of the noble gas atoms, then a single gas rich grain will contain 3,350 Kr atoms, or 12, 75, 385, 398, 1910, and 580 atoms for 78Kr through 86Kr, respectively. The Xe single-grain abundances would be similar. Resonance ionization, an emerging laser-based element analysis technique, is being harnessed to a wide variety of problems in which minute quantities of a particular element need to be measured efficiently in the presence of an overwhelmingly larger background of other materials [14]. By utilizing lasers tuned to specific atomic energy levels of the analyte element, ions are produced selectively in a mass spectrometer with much higher efficiency than possible using conventional methods, such as electron bombardment, thermal ionization, or ion sputtering. In a static resonance ionization system for noble gases, the combination of high ionization efficiency and sample concentrator results in an extremely fast (~3 min. detection half-life vs. ~60 min. for conventional systems) analyzer with a detection limit of ~100 85Kr atoms [15]. In addition to the almost complete absence of interferences, the short analysis time significantly reduces the background contribution of outgassing in the mass spectrometer. Although using a less efficient laser scheme resulting in slightly slower analyses, a similar system has recently been completed and dedicated to extraterrestrial Xe measurements [16]. At the newly formed Institute for Rare Isotope Measurements [17], the noble gas equipment that had previously been at Atom Sciences [14,15] is being re-installed and upgraded to provide routine noble gas measurements from terrestrial and extraterrestrial samples. The present system, data illustrating current capabilities, and improvements that should reduce the detection limit significantly below 100 atoms for both Kr and Xe will be described. An early application will be simultaneous Kr and Xe isotopic measurements from single microscopic interstellar SiC grains. References: [1]Reynolds J. H. (1960) Phys. Rev. Lett., 4, 351-354. [2] Reynolds J. H. and Turner G. (1964) J. Geo. Phys. Res., 69, 3263-3281. [3] Lee T. (1988) (J. F. Kerridge and M. S. Matthews, eds.), 1063-1089, Univ. of Arizona, Tucson. [4] Anders A. and Zinner E. (1993) Meteoritics, 28, 490-514. [5] Burbidge E. M. et al. (1957) Rev. Mod. Phys., 29, 547-650. [6] Lewis R. S. et al. (1994) GCA, 58, 471-494. [7] Zinner E. et al. (1989) GCA, 53, 730-732. [8] Amari S. et al. (1992) Astrophys. J. Lett., 394, L43-L46. [9] Hohenberg C. M. et al. (1990) GCA, 54, 2133-2140. [10] Nichols R. H. Jr. et al. (1991) Meteoritics, 26. [11] Nichols R. H. Jr. et al. (1993) Meteoritics, 28, 410-411. [12] Nittler L. et al. (1995) LPS XXVI, 1057-1058. [13]Hohenberg C. M. (1994) personal communication. [14]Payne M. G. et al. (1994) Rev. Sci. Instrum., 65, 2433-2459. [15] Thonnard N. et al. (1992) Inst. Phys. Conf. Ser. 128, 27-30. [16] Gilmour J. D. et al. (1994) Rev. Sci. Instrum., 65, 617-625. [17] Thonnard N. and Lehmann B. L. (1995) AIP Conf. Proc., 329, 335-338.

  14. Angular correlation studies in noble gases

    NASA Technical Reports Server (NTRS)

    Coleman, P. G.

    1990-01-01

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

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

    SciTech Connect

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

    2004-06-14

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

  16. Noble Gases in a Heterogeneous, Dynamic Mantle

    NASA Astrophysics Data System (ADS)

    Davies, G. F.

    2010-12-01

    The source of unradiogenic noble gases in oceanic basalts has been perhaps the most enigmatic aspect of mantle geochemistry. One popular hypothetical source, a large enriched layer deep in the mantle, is incompatible with geophysical evidence. Not only does seismic tomography preclude a separate lower mantle, but any such layer ought to generate mantle plumes, and associated hotspot swells, much stronger than those observed. The only layering compatible with geophysical evidence is the D region, which is only around 200 km thick and comprises only about 2% of the mantles mass. It is argued that when the major-element heterogeneity of the mantle is more fully considered the noble gas observations can be reconciled with a mantle structure compatible with geophysics and dynamics. The mantle is observed, and expected, to comprise a refractory peridotite matrix containing eclogites and pyroxenites that are more fusible and more enriched in incompatible elements. These heterogeneities will melt deeper, and not all of their off-axis melt will be extracted at mid-ocean ridges, so it will recirculate internally within the mantle. Such recirculated heterogeneities will retain their incompatible elements, and the incompatibles will become concentrated within them, probably from early in Earth history. The heterogeneities, more mafic than ultramafic, will tend to be denser than average mantle through most of the mantles depth. They will therefore tend to accumulate within the D region, as dynamical models have demonstrated for subducted (mafic) oceanic crust. D would thus contain a mixture of subducted oceanic crust, which will have been degassed at the surface, and recirculated heterogeneities carrying noble gases. Dynamical models show that residence times in D are longer than for the mantle interior, so the noble gases in D would tend to be older, as well as higher in concentration. This can explain why mantle plumes, tapping D, contain noble gases that are less radiogenic than mid-ocean ridge basalts. Quantitative models bear this out. This picture requires that the bulk of the mantles noble gases reside in the MORB source, which comprises most of the mantle. Recent estimates of MORB source composition may have underestimated the content of incompatible elements because they are tied to peridotite compositions, which will probably not have equilibrated with all of the incompatibles residing in fusible heterogeneities. Most estimates of MORB source composition also focus on so-called normal MORB, which is actually more depleted than the mean. When more enriched components and plume-related components are considered, the budgets of the noble gases can be plausibly accounted for.

  17. Preserving noble gases in a convecting mantle.

    PubMed

    Gonnermann, Helge M; Mukhopadhyay, Sujoy

    2009-05-28

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

  18. Noble Gases in the Chelyabinsk Meteorites

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  20. Selective Growth of Noble Gases at Metal/Oxide Interface.

    PubMed

    Takahashi, Keisuke; Oka, Hiroshi; Ohnuki, Somei

    2016-02-17

    The locations and roles of noble gases at an oxide/metal interface in oxide dispersed metal are theoretically and experimentally investigated. Oxide dispersed metal consisting of FCC Fe and Y2Hf2O7 (Y2Ti2O7) is synthesized by mechanical alloying under a saturated Ar gas environment. Transmission electron microscopy and density functional theory observes the strain field at the interface of FCC Fe {111} and Y2Hf2O7 {111} whose physical origin emerges from surface reconstruction due to charge transfer. Noble gases are experimentally observed at the oxide (Y2Ti2O7) site and calculations reveal that the noble gases segregate the interface and grow toward the oxide site. In general, the interface is defined as the trapping site for noble gases; however, transmission electron microscopy and density functional theory found evidence which shows that noble gases grow toward the oxide, contrary to the generally held idea that the interface is the final trapping site for noble gases. Furthermore, calculations show that the inclusion of He/Ar hardens the oxide, suggesting that material fractures could begin from the noble gas bubble within the oxides. Thus, experimental and theoretical results demonstrate that noble gases grow from the interface toward the oxide and that oxides behave as a trapping site for noble gases. PMID:26840881

  1. Noble gases and nitrogen on venus

    NASA Astrophysics Data System (ADS)

    Owen, T.

    2003-04-01

    The discovery that solar composition planetesimals must have enriched the heavy elements on Jupiter opens the possibility that such planetesimals could have delivered the anomalous, non-planetary noble gas distribution found on Venus. If so, the nitrogen and carbon (now found as carbon dioxide) must have come from another source. This conclusion is consistent with the evidence now available that nitrogen reached the inner planets as N-compounds rather than as N2. The isotopic ratio of nitrogen on Venus should identify that source, now that we have a reasonably good value for the solar ratio of that number.

  2. 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.

  3. 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.

  4. 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

  5. Diffusive Separation of Noble Gases by adsorption and throat constrictions:Explaining Noble Gas patterns in Sedimentary Rocks

    NASA Astrophysics Data System (ADS)

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

    2002-12-01

    Literature reports of noble gas patterns in sedimentary rocks indicate a commonplace occurrence of both Xe- and Ne-enriched endmembers, which occur either separately or together. Laboratory experiments have shown that noble gases appear to rapidly and weakly physi-adsorb on natural rock material. However, the weak physi-adsorption bond quickly changes to a strong chemi-sorption mode, such that adsorption at low temperature requires a higher temperature to extract the adsorbed component. This suggests that mechanisms are operational in sedimentary rocks that appear to first adsorb and then trap noble gases. More recently, based on measurements of both Xe- and Ne-enrichment in fluids from hydrocarbon systems, it has been suggested that the light and heavy noble gas enrichments occur in the fluid due to direct transfer of noble gas enrichments from the reservoir and/or source rock to the fluid with a subsequent evolution of the fluid. We present a simple model, based on labyrinth-with-constrictions (e.g. Wacker et al., 1986), to explain noble gas enrichment patterns in sedimentary rock that does not require any special process and/or unusual conditions yet provides zeroth order explanations for noble enrichments, trapping and geologic release from/to terrestrial rocks. Using estimates of the relative (1) diffusion coefficients, (2) adsorption coefficients and (3) probabilities for noble gas passage through a constricted throat (all functions of atomic mass), we find the above three properties of noble gases combine to allow a diffusive separation of Ne, Ar, Kr and Xe with a change in boundary condition. This simple theory is consistent with literature reported noble gas enrichment and concentrations in sedimentary rocks. Xe enrichments can be produced as a residual in rock following a decrease in exterior noble gas concentration; Ne enrichments can be produced by an increase in exterior noble gas concentration. The time scale for separation is governed by the above three parameters as well as the characteristic grain size around which the boundary conditions change. Thus noble gas enrichment patterns may be interpretable as `metamorphic-like' process-driven signals reflecting e.g. geothermal heating, diagenesis, metamorphism, methanogenesis, and oil maturation.

  6. Comment on “Atmospheric contamination: A possible source for heavy noble gases in basalts from Loihi Seamount, Hawaii” by D. B. Patterson, M. Honda, and I. McDougall

    NASA Astrophysics Data System (ADS)

    Staudacher, Thomas; Sarda, Philippe; Allègre, Claude J.

    1991-04-01

    Allègre et al. (1983), Staudacher et al. (1986) and Sarda et al. (1988) reported noble gas concentrations and isotopic ratios of basalt glasses from Loihi seamount and Hualalai, Hawaii. The 4He/3He and 40Ar/36Ar ratios of ˜25,000 and 390 ± 50 respectively are different than the air ratio and typical ratios found in MORB glasses. The Ne, Kr and Xe isotopic ratios are the same as those found in air or deep seawater. Based on the different isotopic ratios and the different noble gas concentration patterns of Ne, Ar, Kr and Xe compared to air, deep seawater and MORB, these authors concluded that the noble gases enclosed in vesicles from Loihi and Hualalai basalts are not significantly contaminated by atmospheric noble gases, and that the Loihi and Hualalai basalts came from a separate source, namely the lower mantle, with a distinct noble gas signature. In contrast to the upper mantle, which is highly depleted in noble gases, this lower mantle should be not or only slightly outgassed (Allègre et al., 1986).In a recent publication, Patterson et al. (1990), based on our noble gas data (Staudacher et al., 1986; Sarda et al., 1988), propose that Ne, Ar, Kr and Xe noble gas concentrations in basalt glasses could be plausibly explained by a) contamination of the Loihi plume magma prior to eruption with atmospheric noble gases disolved in deep seawater (which they model by elemental noble gas fractionation of a tholeiitic melt that was equilibrated with seawater derived noble gases), and b) elemental fractionation of noble gases during vesicle formation and vesicle loss. We completely disagree with such an interpretation and show here that their argumentation is inconsistent and incorrect.

  7. Noble gases in Luna 24 core soils

    NASA Technical Reports Server (NTRS)

    Bogard, D. D.; Hirsch, W. C.

    1978-01-01

    Isotopic abundances of the noble gases have been determined in grain size separates of six soils from different depths in the Luna 24 core. Concentrations of cosmogenic Ne-21 in these soils show a complex pattern as a function of soil depth, and are inconsistent with a single stage, in situ production in a static regolith or with a simple model of slow accumulation of previously unirradiated soils followed by a static period. All soils have apparently had a complex pre-irradiation history. Some soils show significant differences in the concentration of cosmogenic Ne-21 between different grain sizes, which is consistent with suggestions that they formed as a mixture of soils with different maturities. The exact subsurface depth relationships of the soils are not known, and several possibilities are discussed. Because of this factor and the complex nature of the soils, the cosmogenic Ne data do not define the depositional-irradiational history of the core. Luna 24 core soils may have been deposited any time during the past 300 million years.

  8. Electron Impact Excitation of Noble Gases

    NASA Astrophysics Data System (ADS)

    Zeman, Vlado; Bartschat, Klaus

    1998-05-01

    We have extended our Breit-Pauli R-matrix work [1,2] to model electron impact excitation of the [np^5(n+1)s] and [np^5(n+1)p] states in the noble gases Ne--Xe. Total and differential cross sections, the polarization of emitted light, and spin asymmetry parameters will be presented for incident electron energies between threshold and 30 eV. The results will be analyzed and compared with a large amount of recent experimental data [3--8]. 1. V. Zeman et al., Phys. Rev. Lett. 79, 1825 (1997) 2. V. Zeman and K. Bartschat, J. Phys. B 30, 4609 (1997) 3. C. Norén et al., Phys. Rev. A53, 3253 (1996) and 54, 510 (1996) 4. T.J. Gay et al., Phys. Rev. A53, 1623 (1996) 5. D.H. Yu et al., Phys. Rev. Lett. 78, 2724 (1997); J. Phys. B 30, L461 5. (1997); J. Phys. B 30, 1799 (1997) 6. J.E. Chilton et al., Phys. Rev. A57, 267 (1998) 7. M.A. Khakoo, private communication (1998) 8. M. Dümmler, G.F. Hanne and J. Kessler, J. Phys. B 28, 2985 (1995)

  9. The Noble Gases in A-Level Chemistry.

    ERIC Educational Resources Information Center

    Marchant, G. W.

    1983-01-01

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

  10. The diverse biological properties of the chemically inert noble gases.

    PubMed

    Winkler, David A; Thornton, Aaron; Farjot, Géraldine; Katz, Ira

    2016-04-01

    The noble gases represent an intriguing scientific paradox. They are extremely inert chemically but display a remarkable spectrum of clinically useful biological properties. Despite a relative paucity of knowledge of their mechanisms of action, some of the noble gases have been used successfully in the clinic. Studies with xenon have suggested that the noble gases as a class may exhibit valuable biological properties such as anaesthesia; amelioration of ischemic damage; tissue protection prior to transplantation; analgesic properties; and a potentially wide range of other clinically useful effects. Xenon has been shown to be safe in humans, and has useful pharmacokinetic properties such as rapid onset, fast wash out etc. The main limitations in wider use are that: many of the fundamental biochemical studies are still lacking; the lighter noble gases are likely to manifest their properties only under hyperbaric conditions, impractical in surgery; and administration of xenon using convectional gaseous anaesthesia equipment is inefficient, making its use very expensive. There is nonetheless a significant body of published literature on the biochemical, pharmacological, and clinical properties of noble gases but no comprehensive reviews exist that summarize their properties and the existing knowledge of their models of action at the molecular (atomic) level. This review provides such an up-to-date summary of the extensive, useful biological properties of noble gases as drugs and prospects for wider application of these atoms. PMID:26896563

  11. Photosensitive dopants for liquid noble gases

    DOEpatents

    Anderson, David F.

    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.

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

    SciTech Connect

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

    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.

  13. 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.

  14. [Neuroprotection by noble gases: New developments and insights].

    PubMed

    Fahlenkamp, A V; Rossaint, R; Coburn, M

    2015-11-01

    Noble gases are chemically inert elements, some of which exert biological activity. Experimental neuroprotection in particular has been widely shown for xenon, argon and helium. The underlying mechanisms of action are not yet fully understood. Besides an interference with neuronal ion-gated channels and cellular signaling pathways as well as anti-apoptotic effects, the modulation of neuroinflammation seems to play a crucial role. This review presents the current knowledge on neuroprotection by noble gases with a focus on interactions with the neuronal-glial network and neuroinflammation and the perspectives on clinical applications. PMID:26329914

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

    NASA Astrophysics Data System (ADS)

    Schwenzer, S. P.; Ott, U.

    2014-11-01

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

  16. 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.

  17. Noble Gases in the Hamlet Meteorite (LL4)

    NASA Astrophysics Data System (ADS)

    Amari, S.; Sabe, Y.; Shiraishi, T.; Matsuda, J.

    2014-09-01

    We analyzed noble gases in a bulk sample and an HF-HCl residue of Hamlet (LL4). The Xe composition of the residue shows that no diamond is contained in the residue. The 20Ne/22Ne ratio of Hamlet Ne-Q has been determined to be 11.0 ± 0.5.

  18. Explosively Generated Plasmas in Noble Gases

    NASA Astrophysics Data System (ADS)

    Boswell, C. J.; Carney, J. R.; Lightstone, J. M.; Wilkinson, J.; Pangilinan, G.

    2007-11-01

    Non-ideal plasmas occur as a result of the stimulation of matter by strong shocks, detonation waves, or concentrated laser irradiation. Since all of these methods of generating non-ideal plasmas are already in use to address other problems, we focus on a detailed understanding of this plasma. In particular, we study the generation of this plasma by strong, ionizing guided shock waves. The shock wave in the gas is generated by an explosive located at one end of a guide tube filled with a noble gas. The detonation produces a shock wave strong enough to ionize the gas. Spectral line emission profiles, recorded with a streak emission spectroscopy system, are used to ascertain neutral and ionized gas properties. The electric and magnetic fields are measured by electrostatic probes and magnetic induction coils which permit the measurement of the temperature, density, and electric potential of the non-ideal plasma; as well as the flow of net electric charges respectively. The results demonstrate there is a mixing of the detonation products and the noble gas and that there is a pulse of electrons that travel ahead of the shock wave as it travels down the guide tube.

  19. Noble gases as cardioprotectants – translatability and mechanism

    PubMed Central

    Smit, Kirsten F; Weber, Nina C; Hollmann, Markus W; Preckel, Benedikt

    2015-01-01

    Several noble gases, although classified as inert substances, exert a tissue-protective effect in different experimental models when applied before organ ischaemia as an early or late preconditioning stimulus, after ischaemia as a post-conditioning stimulus or when given in combination before, during and/or after ischaemia. A wide range of organs can be protected by these inert substances, in particular cardiac and neuronal tissue. In this review we summarize the data on noble gas-induced cardioprotection, focusing on the underlying protective mechanisms. We will also look at translatability of experimental data to the clinical situation. PMID:25363501

  20. Fullerenes: an extraterrestrial carbon carrier phase for noble gases.

    PubMed

    Becker, L; Poreda, R J; Bunch, T E

    2000-03-28

    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

  1. 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

  2. Recent Experimental Advances to Determine (noble) Gases in Waters

    NASA Astrophysics Data System (ADS)

    Kipfer, R.; Brennwald, M. S.; Huxol, S.; Mächler, L.; Maden, C.; Vogel, N.; Tomonaga, Y.

    2013-12-01

    In aquatic systems noble gases, radon, and bio-geochemically conservative transient trace gases (SF6, CFCs) are frequently applied to determine water residence times and to reconstruct past environmental and climatic conditions. Recent experimental breakthroughs now enable ● to apply the well-established concepts of terrestrial noble gas geochemistry in waters to the minute water amounts stored in sediment pore space and in fluid inclusions (A), ● to determine gas exchange processes on the bio-geochemical relevant time scales of minutes - hours (B), and ● to separate diffusive and advective gas transport in soil air (C). A. Noble-gas analysis in water samples (< 1 g) facilitates determining the solute transport in the pore space and identifying the origin of bio- and geogenic fluids in (un) consolidated sediments [1]. Advanced techniques that combine crushing and sieving speleothem samples in ultra-high-vacuum to a specific grain size allow to separate air and water-bearing fluid inclusions and thus enables noble-gas-based reconstruction of environmental conditions from water masses as small as 1mg [2]. B. The coupling of noble gas analysis with approaches of gas chromatography permits combined analysis of noble gases and other gases species (e.g., SF6, CFCs, O2, N2) from a single water sample. The new method substantially improves ground water dating by SF6 and CFCs as excess air is quantified from the same sample and hence can adequately be corrected for [3]. Portable membrane-inlet mass spectrometers enable the quasi-continuous and real-time analysis of noble gases and other dissolved gases directly in the field, allowing, for instance, quantification of O2 turnover rates on small time scales [4]. C. New technical developments perfect 222Rn analysis in water by the synchronous the determination of the short-lived 220Rn. The combined 220,222Rn analysis sheds light on the emanation behaviour of radon by identifying soil water content to be the crucial control of 220Rn occurrence in the environment, e.g., making an argument why 220Rn is not detectable in water, but in soil air. As 220Rn occurrence is of 'very local origin' the combined analysis of 220,222Rn in soil air allows differentiating between advective and diffusive soil gas transport [5]. By discussing these recent achievements, we intend to stimulate a broader discussion to identify future applications of noble and other gases in (un) conventional aquatic systems, such as blood. [1] Tomonaga et al. (2011) Limnol. Oceanogr. Methods, 9, 42-49, doi:10:4319/lom.2011.9.42. [2] Vogel et al. (2013) Geochem. Geophys. Geosyst., 14, doi:10.1002/ggge.20164. [3] Brennwald et al. (2013) Environ. Sci. Technol., Article ASAP, DOI: 10.1021/es401698p. [4] Mächler et al. (2012) Environ. Sci. Technol., 47, 7060-7066. [5] Huxol et al. Environ. Sci. Technol., in revision.

  3. Argon retentivity of carbonaceous materials: feasibility of kerogen as a carrier phase of Q-noble gases in primitive meteorites

    NASA Astrophysics Data System (ADS)

    Osawa, T.; Hirao, N.; Takeda, N.; Baba, Y.

    2009-08-01

    Extremely large amounts of heavy noble gases are concentrated in phase Q, which seems to be a carbonaceous phase analogous to terrestrial Type III kerogen. Phase Q must have very high noble gas retentivity based on the presence of such extremely large amounts of heavy noble gases in a very minor fraction of the meteorite. To verify that kerogen is a carrier phase of Q-noble gases, X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) using synchrotron radiation were carried on for kerogens (coals) and carbon allotropes that had been bombarded by 3-keV Ar ions, and the Ar retentivities of the two materials were compared. This comparison of the estimated Ar concentrations in the target materials revealed that carbon allotropes (graphite, fullerene, carbon nanotube, and diamond) have a much higher Ar retentivity than kerogens. This unexpected result clearly shows that the terrestrial kerogens tested in our study are not suitable as a carrier phase of Ar and, consequently, that phase Q may not be similar to the terrestrial kerogen tested. If heavy noble gases are really concentrated in carbonaceous components of primitive meteorites, phase Q may have a more ordered structure than terrestrial kerogen based on the fact that the greatest difference between terrestrial kerogen and carbon allotropes is the degree of order of the molecular structure.

  4. 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.

  5. Howardite Noble Gases as Indicators of Asteroid Surface Processing

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1993-07-01

    Experiments on ion implantation were performed in order to study the release mechanisms of solar particles from lunar soil grains. Helium, neon, and argon ions were implanted into olivine and ilmenite. The release temperatures of noble gases were investigated by heating samples stepwise; the results show that they depend on irradiation energy and dose. We conclude that the release temperature is related to the size of bubbles in which noble gases are trapped: noble gases in small and large bubbles are released at 400-600 C and 800-1200 C, respectively. In Ne and Ar implantation experiments into olivine, a component was released during recrystallization of amorphized surfaces. Based on these experimental results, we suggest that components released from lunar ilmenite grains at different temperatures would correspond to solar particles of different energies. We also suggest that He and Ne of solar wind energy (about 1 keV/amu) should be retained in lunar ilmenite grains, while they should be lost from olivine grains.

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

    NASA Technical Reports Server (NTRS)

    Crabb, J.; Anders, E.

    1982-01-01

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

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

    SciTech Connect

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

    2000-01-24

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

  9. Noble gases, K, U, Th, and Pb in native gold

    NASA Astrophysics Data System (ADS)

    Engster, O.; Niedermann, S.; Thalmann, C.; Frei, R.; Kramers, J.; KräHenbühl, U.; Liu, Y. Z.; Hofmann, B.; Boer, R. H.; Reimold, W. U.; Bruno, L.

    1995-12-01

    We present determinations of the noble gas and Pb isotopic abundances and of K, Th, and U concentrations of native gold. Our results demonstrate that gold is an excellent carrier for crustal volatiles, but direct dating of gold using the U, Th-4He, 40K-40Ar, and U fission Xe methods was not successful for various reasons. The main significance of this work is the great sensitivity of gold for trapped gases as well as for gases that were produced in situ which gives the prospects of using gold and its fluid and solid inclusions for the study of paleogas composition. Numerous nuclear effects characterize the noble gas inventory of placer gold from Switzerland and Italy, vein gold from Italy, South Africa, and Venezuela, and lode gold from South Africa. The degassing patterns obtained by mass spectrometry show a low-temperature release of volatiles around 500°C from fluid inclusions mainly in vein gold and a high-temperature release from solid inclusions and the gold itself. The low-temperature volatiles represent species that were trapped when the gold crystallized. We investigated the following trapped species: the isotopes of He, Ne, Ar, Kr, Xe, and Pb, and the abundances of K, U, Th, H2O, and CO2. The crustal gases trapped by gold comprise 3He from 6Li(n,α)3H → β- → 3He, 4He and 40Ar from the U, Th, and K decay, and Xe from 238U fission. We observe 4He/40Ar = 3.9 for the radiogenic trapped gases of tertiary gold and a ratio of 1.4 for Archean gold. These ratios are consistent with the production ratios from U and K at the respective times and demonstrate that gold can be used as a sampler of ancient atmospheric gases. The concentrations of U and Th range from a few parts per billion to a few parts per million, and those of K and Pb range up to some tens of parts per million. The antiquity of trapped Pb is indicated by the Pb-Pb model age of about 3000 Ma for the lead extracted from vein gold and quartz of the Lily gold mine (South Africa). Gold also contains noble gases produced in situ by U, Th, and K decay. We obtained 4He up to the extremely high concentration of 6.8×10-2 cm3 STP/g (STP: atmospheric pressure and 0°C) for gold separated from a specimen of the Witwatersrand West Rand gold fields, indicating that this gold has a large U content.

  10. Noble gases and radiocarbon in natural gas hydrates

    NASA Astrophysics Data System (ADS)

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

    2002-05-01

    In samples of pure natural gas hydrates from Hydrate Ridge, Cascadia Margin, virtually no helium and neon components are present providing evidence that the light noble gases are not incorporated into the structure of natural methane hydrates. In contrast, the hydrates contain significant amounts of argon, krypton and xenon. These gases show a distinct fractionation pattern, with the heavier ones preferentially incorporated into the gas hydrate structure. The hydrate methane is devoid of 14C indicating that there is no contribution of a recent (14C-active) organic carbon reservoir to the hydrate carbon pool. On the basis of the δ13C and δ2H signature, it appears that microbial CO2-reduction is the dominant CH4 production pathway.

  11. 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.

  12. A preliminary survey of noble gases at Dixie Valley, Nevada

    SciTech Connect

    Kennedy, B.M.; Benoit, D.; Truesdell, A.H.

    1996-12-31

    A preliminary survey of noble gas abundances and isotopic compositions in production fluids from four high pressure separator stations providing steam to the dual flash Dixie Valley Geothermal Plant has been completed. The atmospheric noble gases are dominated by dissolved gases introduced with the injection fluid, a mixture of flashed degassed brine and condensate equilibrated with air in the cooling tower. Excess helium, however, represents a primary reservoir fluid and variations in the amount of excess can be used to monitor the changing proportion of injectate in the production fluid. The helium component associated with the reservoir fluid has an isotopic composition (0.70 - 0.76 Ra) implying that {approximately}7.5% of the helium in the 1995 Dixie Valley reservoir fluid is mantle-derived. The Dixie Valley geothermal field is closely related to the range-front normal fault of the Stillwater Range. Assuming fluid transport along the fault from deeper sources and using a one-dimensional steady-state advection model, the helium content and isotopic composition of the reservoir fluid predicts an average fluid flow rate of virgin fluid from depth of {approximately} 7 mm/yr. This is significantly less than injectate flow rates within the reservoir estimated from tracer tests (i.e. 5 - 120 m/day).

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

    NASA Technical Reports Server (NTRS)

    Lancet, M. S.; Anders, E.

    1973-01-01

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

  14. Exploring the Effects on Lipid Bilayer Induced by Noble Gases via Molecular Dynamics Simulations

    PubMed Central

    Chen, Junlang; Chen, Liang; Wang, Yu; Wang, Xiaogang; Zeng, Songwei

    2015-01-01

    Noble gases seem to have no significant effect on the anesthetic targets due to their simple, spherical shape. However, xenon has strong narcotic efficacy and can be used clinically, while other noble gases cannot. The mechanism remains unclear. Here, we performed molecular dynamics simulations on phospholipid bilayers with four kinds of noble gases to elucidate the difference of their effects on the membrane. Our results showed that the sequence of effects on membrane exerted by noble gases from weak to strong was Ne, Ar, Kr and Xe, the same order as their relative narcotic potencies as well as their lipid/water partition percentages. Compared with the other three kinds of noble gases, more xenon molecules were distributed between the lipid tails and headgroups, resulting in membrane’s lateral expansion and lipid tail disorder. It may contribute to xenon’s strong anesthetic potency. The results are well consistent with the membrane mediated mechanism of general anesthesia. PMID:26601882

  15. Exploring the Effects on Lipid Bilayer Induced by Noble Gases via Molecular Dynamics Simulations.

    PubMed

    Chen, Junlang; Chen, Liang; Wang, Yu; Wang, Xiaogang; Zeng, Songwei

    2015-01-01

    Noble gases seem to have no significant effect on the anesthetic targets due to their simple, spherical shape. However, xenon has strong narcotic efficacy and can be used clinically, while other noble gases cannot. The mechanism remains unclear. Here, we performed molecular dynamics simulations on phospholipid bilayers with four kinds of noble gases to elucidate the difference of their effects on the membrane. Our results showed that the sequence of effects on membrane exerted by noble gases from weak to strong was Ne, Ar, Kr and Xe, the same order as their relative narcotic potencies as well as their lipid/water partition percentages. Compared with the other three kinds of noble gases, more xenon molecules were distributed between the lipid tails and headgroups, resulting in membrane's lateral expansion and lipid tail disorder. It may contribute to xenon's strong anesthetic potency. The results are well consistent with the membrane mediated mechanism of general anesthesia. PMID:26601882

  16. Exploring the Effects on Lipid Bilayer Induced by Noble Gases via Molecular Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Chen, Junlang; Chen, Liang; Wang, Yu; Wang, Xiaogang; Zeng, Songwei

    2015-11-01

    Noble gases seem to have no significant effect on the anesthetic targets due to their simple, spherical shape. However, xenon has strong narcotic efficacy and can be used clinically, while other noble gases cannot. The mechanism remains unclear. Here, we performed molecular dynamics simulations on phospholipid bilayers with four kinds of noble gases to elucidate the difference of their effects on the membrane. Our results showed that the sequence of effects on membrane exerted by noble gases from weak to strong was Ne, Ar, Kr and Xe, the same order as their relative narcotic potencies as well as their lipid/water partition percentages. Compared with the other three kinds of noble gases, more xenon molecules were distributed between the lipid tails and headgroups, resulting in membrane’s lateral expansion and lipid tail disorder. It may contribute to xenon’s strong anesthetic potency. The results are well consistent with the membrane mediated mechanism of general anesthesia.

  17. Insights into deep carbon derived from noble gases

    NASA Astrophysics Data System (ADS)

    Lollar, B. Sherwood; Ballentine, C. J.

    2009-08-01

    Science and society are faced with two challenges that are inextricably linked: fossil-fuel energy dependence and rising levels of atmospheric carbon dioxide. Management of remaining hydrocarbon resources, the search for cleaner fuels and increasing interest in subsurface carbon storage all require a better understanding of the deep terrestrial carbon cycle. The coupling of noble gas and carbon chemistry provides an innovative approach to understanding this deep carbon. Whereas carbon geochemistry and isotopic signatures record the history of inorganic and organic reactions that control carbon mobility, the inert noble gases provide unique tracers of fluid origin, transport and age. Together, they have been used to show that groundwater has a key role as both the sink for geologically sequestered carbon dioxide, and in the transport and emplacement of hydrocarbon gas deposits. Furthermore, these tracers have also been used to show that groundwater and subsurface microbiology jointly influence the formation and alteration of fossil-fuel deposits to an extent not previously recognized. The age and distribution of groundwater in fractures in the Earth's crust exert important controls on the Earth's deepest microbial communities.

  18. Description, chemical composition and noble gases of the chondrite Nogata

    NASA Astrophysics Data System (ADS)

    Shima, M.; Murayama, S.; Okada, A.; Yabuki, H.; Takaoka, N.

    1983-06-01

    Microscopic, electron-microprobe, chemical-composition, and noble-gas-isotopic-abundance studies of a 20-g sample of the ordinary chondrite Nogata are reported. The historical report of the fall of the chondrite at Nogata, Japan in the year 861 is supported by C-14 dating of the wooden box in which it has been stored in a Shinto shrine. The measurement data are presented in tables and discussed. Except for a low Fe content, the chemical composition and petrological structure of the chondrite are consistent with an L6 classification. Nogata is found to be more lightly shocked and to contain relatiely more radiogenic and spallogenic noble gases than other L chondrites. The gas-retention ages calculated for Nogata are 4.5 (He-4) and 4.7 (Ar-40) x 10 to the 9th years; the cosmic-ray-exposure age is about 4 x 10 to the 7th years. It is suggested that the metamorphism of the chondrite was completed within about 10 to the 8th years of the formation of its parent body.

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Baudis, Laura

    2014-09-01

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

  1. Degassing mechanisms of noble gases from carbonado diamonds

    NASA Technical Reports Server (NTRS)

    Zashu, S.; Hiyagon, H.

    1994-01-01

    Diamonds are unique samples for inferring ancient mantle conditions, because of their enormous stability, antiquity and also of mantle origin. However, as temperatures in the mantle where diamonds have existed are very high (greater than 1000 C) and residence time of some diamonds could be more than a few billion years, it is imperative to examine whether or not diamonds have retained their pristine characteristics, especially those of noble gases, under such extreme conditions. As discussed in a review article by Ozima, there are rather large variations in the diffusivity of helium in diamonds obtained in the early determinations. The data are also limited to temperatures higher than 1200 C. In the present study, we conducted more refined diffusion experiments for He using carbonado diamonds, which have large amounts of radiogenic (4)He approximately 10(exp -2) cu cm STP/g. On the basis of the experimentally estimated diffusion coefficients, we will discuss retentivity of He in diamonds in the mantle condition.

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

    NASA Astrophysics Data System (ADS)

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

    1993-07-01

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

  3. Solar Noble Gases from ACFER 111 Metal Etched in Vacuo

    NASA Astrophysics Data System (ADS)

    Pedroni, A.; Begemann, F.

    1992-07-01

    Regolith grains dissolved by stepwise etching release a mixture of near-surface implanted Solar Wind gases (SW) and a deeper- sited, isotopically heavier component attributed to Solar Energetic Particles (SEP) (1,2,3). In all regolith materials examined so far the elemental abundance ratios in both components are distinctly different from the canonical solar values (4). The differences are generally explained to be owing to diffusive elemental fractionation although there is no strong evidence that upon their implantation the composition of the gases was indeed solar. In contrast, the solar noble gases present in the H3-H6 chondritic regolith breccia Acfer 111 appear to be nearly unfractionated and thus offer a unique chance for more accurate analyses. A magnetic fraction of Acfer 111 matrix, consisting of approx. 80% metal and 20% silicates, was etched with a 60 g/mol aqueous solution of HNO3 in a high-vacuum extraction line similar to that in (1). The gases released were drawn off in steps and analyzed; the experiment was stopped when ~97% of the metal and ~50% of the silicates were dissolved. As etching proceeds, the isotopic composition of the released gases changes in a pattern similar to that observed previously in other regolithic materials. The isotopic composition of solar neon decreases from ^20Ne/^22Ne=13.1 in the first step to ^20Ne/^22Ne=11.6, which can be interpreted as a change of the mixing ratio of SW (^20Ne/^22Ne=13.7) and SEP (^20Ne/^22Ne=11.3) neon. The isotopic compositions of solar He, Ar, and Kr are consistent with their also being mixtures of SW and SEP having compositions reported previously (2,3), although our data are compromised to some extent by the presence of planetary gases extracted from the silicates and, in the first steps, by atmospheric contamination probably present in terrestrial weathering products (mostly rust). The elemental composition of noble gases released from Acfer 111 was distinct from previous experiments: The (^4He/^20Ne)solar ratio is initially 585 (as in the Solar Wind), increases smoothly as etching proceeds, and, after reaching a maximum around 680, decreases to approximately 230 (Fig. 1, upper panel). These variations, especially in the last two steps of the experiment, where the solar gases are depleted in He, are most probably due to different depth distributions for He and Ne, with the implantation range of the lighter nuclide being shorter than that of the heavier one (5). Ignoring the implantation range effect, the variations imply that the ^4He/^20Ne ratio of the SW and the SEP do not differ by more than 20%. Although we do not recognize significant variations in the (^20Ne/^36Ar)solar ratio (Fig. 1 lower panel), possibly because of larger experimental errors, the data imply again that SW and the SEP do not differ by more than 20% in the ^20Ne/^36Ar ratio also. References (1) Wieler et al. (1986) GCA 50, 1997-2017. (2) Benkert et al. (1988) LPSC IXX. (3) Wieler et al. (1992) LPSC XXIII (4) Anders and Grevesse GCA 53, 197-214 (5) Kiko et al. (1978) Proc. Lunar Planet. Sci. Conf. 9th, 1655-1665.

  4. Noble Gases in the LEW 88663 L7 Chondrite

    NASA Astrophysics Data System (ADS)

    Miura, Y. N.; Sugiura, N.; Nagao, K.

    1995-09-01

    LEW88663 and some meteorites (e.g. Shaw) are the most highly metamorphosed meteorites among L group chondrites. Although the abundances of lithophile elements and oxygen isotopic compositions of the L7 chondrite LEW88663 (total recovered mass: 14.5g) are close to those of the range for L chondrites [1,2], metallic iron is absent and concentrations of siderophile elements are about half of typical values for L chondrites [3,4]. Petrographical and geochemical observation suggested that this meteorite has experienced partial melting [5]. As a part of our study on differentiated meteorites, we also investigated noble gases in this meteorite. We present here noble gas compositions of LEW88663 and discuss history of this meteorite. In addition, we will consider whether there is any evidence for bridging between chondrites and achondrites. Noble gases were extracted from a whole rock sample weighing 66.31 mg by total fusion, and all stable noble gas isotopes as well as cosmogenic radioactive 81Kr were analyzed using a mass spectrometer at ISEI, Okayama University. The results are summarized in the table. The concentrations of cosmogenic ^3He, ^21Ne, and ^38Ar are 7.3, 1.6 and 3.1x10^-8 cm^3STP/g, respectively. The cosmic-ray exposure ages based on them are calculated to be 4.7, 6.9 and 8.8 m.y., respectively, using the production rates proposed by [6, 7] and mean chemical compositions of L chondrites. The shorter cosmic-ray exposure ages T(sub)3 and T(sub)21 than T(sub)38 would be due to diffusive loss of lighter noble gases from the meteorite. The concentrations of trapped Kr and Xe in LEW88663 are lower than those for L6 chondrites [8], supporting thermal metamorphism for the meteorite higher than that for L6 chondrites. The Kr and Xe are isotopically close to those of the terrestrial atmospheric Kr and Xe, and elemental abundance ratios for Ar, Kr and Xe suggest adsorbed noble gas patterns of the terrestrial atmosphere. The terrestrial atmospheric Ar, Kr and Xe (most likely terrestrial contamination in origin) rather than chondritic ones seem to be dominant in LEW88663. A K-Ar age of 4.3 +/- 0.2 b.y. is obtained assuming K content of 660 ppm by [9], implying radiogenic ^40Ar is almost retained. Because of low abundance of trapped Xe in the meteorite compared with the abundances in other chondrites, ^244Pu-derived fission Xe could be evaluated more precisely. According to the measured Xe data (for this, three isotope plots such as ^134Xe/^130Xe versus ^136Xe/^130Xe are useful), we conclude that Xe in LEW88663 is the mixture of ^244Pu-derived fission Xe and the terrestrial atmospheric Xe with possibility that a small amount of chondritic Xe is contained. Using the same procedure described in [10], we obtained excess ^136Xe concentration, 1.4 x 10^-12 cm^3STP/g with about 20% uncertainty, of which about 3% is from contribution of ^238U-derived ^136Xe if average U content for L chondrite (14 ppb) is assumed. The calculated Pu abundance of 0.21 ppb is slightly higher than those reported for L chondrites Barwell (0.11 +/- 0.05 ppb [11]) and Marion (0.10+/-0.40 ppb [11]). Acknowledgments: We thank Meteorite Working Group for providing the sample. We are also grateful to Dr. D. Mittlefehldt for showing us his chemical composition data. This work is supported by Research Fellowships of the Japan Society for the Promotion of Science for Young Scientists. References: [1] Mason B. et al. (1992) Antarc. Meteorite Newsletter, 15(2), 30. [2] Mason B. and Marlow R. (1992) Antarc. Meteorite Newsletter, 15(1), 16. [3] Davis A. M. et al. (1993) LPS XXIV, 375-376. [4] Mittlefehldt D. W. (1993) Meteoritics, 28, 401-402. [5] Hervey R. P. (1993) Meteoritics, 28, 360. [6] Eugster O. (1988) GCA, 52, 1649-1662. [7] Marti K. and Graf T.(1992) Annu. Rev. Earth Planet Sci., 20, 221-243. [8] E.g. Marti K. (1967) EPSL, 2, 193-196. [9] Mittlefehldt D. W., personal communication. [10] Miura Y. et al. (1993) GCA, 57, 1857-1866. [11] Hagee B. et al. (1990) GCA, 54, 2847-2858. Table 1 shows noble gases in L7 chondrite LEW88663 (66.31 mg).

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

    SciTech Connect

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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  7. Using noble gases to investigate mountain-front recharge

    NASA Astrophysics Data System (ADS)

    Manning, Andrew H.; Solomon, D. Kip

    2003-05-01

    Mountain-front recharge is a major component of recharge to inter-mountain basin-fill aquifers. The two components of mountain-front recharge are (1) subsurface inflow from the mountain block (subsurface inflow), and (2) infiltration from perennial and ephemeral streams near the mountain front (stream seepage). The magnitude of subsurface inflow is of central importance in source protection planning for basin-fill aquifers and in some water rights disputes, yet existing estimates carry large uncertainties. Stable isotope ratios can indicate the magnitude of mountain-front recharge relative to other components, but are generally incapable of distinguishing subsurface inflow from stream seepage. Noble gases provide an effective tool for determining the relative significance of subsurface inflow, specifically. Dissolved noble gas concentrations allow for the determination of recharge temperature, which is correlated with recharge elevation. The nature of this correlation cannot be assumed, however, and must be derived for the study area. The method is applied to the Salt Lake Valley Principal Aquifer in northern Utah to demonstrate its utility. Samples from 16 springs and mine tunnels in the adjacent Wasatch Mountains indicate that recharge temperature decreases with elevation at about the same rate as the mean annual air temperature, but is on average about 2 °C cooler. Samples from 27 valley production wells yield recharge elevations ranging from the valley elevation (about 1500 m) to mid-mountain elevation (about 2500 m). Only six of the wells have recharge elevations less than 1800 m. Recharge elevations consistently greater than 2000 m in the southeastern part of the basin indicate that subsurface inflow constitutes most of the total recharge in this area.

  8. Laboratory shock emplacement of noble gases, nitrogen, and carbon dioxide into basalt, and implications for trapped gases in shergottite EETA 79001

    SciTech Connect

    Wiens, R.C.; Pepin, R.O.

    1988-02-01

    Basalt samples have been analyzed mass spectrometrically for shock-implanted noble gases, N/sub 2/, and CO/sub 2/ after exposure to 20-60 GPa (200-600 kbar) shock in the presence of .0045-3.0 atm of ambient gas. Abundances of emplaced gases varied linearly with ambient gas pressure for constant shock pressure, and gas emplacement was most efficient in the range of 35-50 GPa shock pressure. Uncrushed samples shocked in this range gave emplacement efficiencies of 2.0-6.7% for heavy noble gases and nitrogen, while powdered samples with higher effective porosity yielded 40-50% efficiencies, indicating that approx. 50% of noble gases and nitrogen available in pores paces was emplaced. No elemental or isotopic fractionation was detected with Ar, Kr, Xe, or N/sub 2/. Helium and, in some samples, Ne were lost by diffusions subsequent to shock. Emplacement efficiencies for CO/sub 2/ averaged a factor of 1.8 +/- 0.2 greater than those of N/sub 2/ and noble gases in 4 samples with 20-50 GPa shock, and yielded 3.2 times greater efficiency in a sample shocked to 60 GPa. Enhanced CO/sub 2/ emplacement is thought to be due to reaction with silicate materials. Trapped gases in EETA 79001 glass were probably emplaced by shock. However, apparent emplacement efficiencies are somewhat higher than even shocked powder samples. Possible explanations for the difference include atmospheric overpressure at the time of shock, trapping of gas already in vugs by intruding melt material, or collapse of gas-filled vugs to form gas-laden glass inclusions.

  9. 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.

  10. 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.

  11. Noble Gases and Nitrogen Released from a Lunar Soil Pyroxene Separate by Acid Etching

    NASA Astrophysics Data System (ADS)

    Rider, P. E.

    1993-07-01

    We report initial results from a series of experiments designed to measure recently implanted solar wind (SW) ions in lunar soil mineral grains [1]. An acid-etching technique similar to the CSSE method developed at ETH Zurich was used to make abundance and isotope measurements of the SW noble gas and nitrogen compositions. Among the samples examined was a pyroxene separate from soil 75081. It was first washed with H2O to remove contamination from the sample finger walls and grain surfaces. H2O also acted as a weak acid, releasing gases from near-surface sites. Treatment with H2SO3 followed the water washes. Acid pH (~1.8 to ~1.0) and temperature (~23 degrees C to ~90 degrees C) and duration of acid attack (several minutes to several days) were varied from step to step. Finally, the sample was pyrolyzed in several steps to remove the remaining gases, culminating with a high-temperature pyrolysis at 1200 degrees C. Measurements of the light noble gases were mostly consistent with those from previous CSSE experiments performed on pyroxene [2,3]. It should be noted, however, that the Zurich SEP component was not easily distinguishable in the steps where it was expected to be observed. We suspect our experimental protocol masked the SEP reservoir, preventing us from seeing its distinctive signature. The most interesting results from this sample are its Kr and Xe isotopic and elemental compositions. Pyroxene apparently retains heavy noble gases as well as ilmenite (and plagioclase [4]). The heavy noble gas element ratios from this sample along with those previously reported [5,6] are, however, considerably heavier than the theoretically determined "solar system" values [7,8]. Explanations for the difference include the possibility that the derivations are incorrect, that there is another component of lunar origin mixing with the solar component, or that some type of loss mechanism is altering the noble gas reservoirs of the grains. The Kr and Xe isotopic compositions for the two acid-etch steps most likely to have released SW gases were identical to the "solar" values reported by the Zurich group [5]. The krypton from both steps appeared to be mixtures of "solar" krypton, an isotopically heavier component (perhaps the Zurich SEP component [5]), and a spallation component. There was, however, no evidence for such a mixture in the xenon. The compositions of the two acid-etch steps were clearly combinations of a solar Xe component and a Xe spallation component. They were also identical to that of U-Xe [9] for isotopes up to 132Xe, with the exception of an ~300 per mil enhancement of the 126Xe/132Xe ratio. This anomaly does not appear to be an artifact of spallation correction. These measurements constitute the first experimental verification of the U-Xe composition for isotopes lighter than 134Xe. Persistent contamination problems and the possibility of nitrogen being held back in the acid residue during the etching process make interpretation of the nitrogen data uncertain. However, results from the steps not obviously affected by contamination show an enhancement of N over Ar by 2x to 12x the "solar" value (from [8]). References: [1] Rider P. E. and Pepin R. O. (1993) GCA, submitted. [2] Wieler R. et al. (1986) GCA, 50, 1997-2017. [3] Benkert J.-P. (1989) Ph.D. thesis, ETH Zurich (No. 8812). [4] Wieler R. (1993) personal communication. [5] Wieler R. et al. (1992) LPS XXIII, 1525-1526. [6] Wieler R. et al. (1993) LPS XXIV, 1519-1520. [7] Anders E. and Grevesse N. (1989) GCA, 53, 197-214. [8] Cameron A. G. W. (1982) In Essays in Nuclear Physics (Barnes et al., eds.), 23-43. [9] Pepin R. O.(1991) Icarus, 92, 2-79.

  12. No Evidence for Trapped Noble Gases in CAIs

    NASA Astrophysics Data System (ADS)

    Vogel, N.; Baur, H.; Leya, I.; Wieler, R.

    2003-12-01

    Refractory inclusions (CAIs) in meteorites probably are the first solids in the solar system. Although formed at high temperatures, CAIs are reported to contain trapped noble gases [1,2,3] which would provide information on CAI formation and solar system evolution. We reassessed this question by measuring Ne and Ar in CAIs of primitive chondrites (Allende, Axtell, Efremovka) by IR-laser extraction suitable for measuring low gas concentrations [4]. We chose meteorites with different preatmospheric radii, exposure ages, and degrees of alteration to take into account those effects on CAI noble gas compositions. 20Ne/22Ne is below 0.9 indicating the absence of common trapped Ne. We suggest that elevated 20Ne/22Ne of [1,2,5] resulted from contamination of their CAI samples with matrix rich in trapped Ne. 21Ne/22Ne is 0.72 to 0.86; more altered CAIs show the lower ratios. The Ne might be a mixture of chondritic cosmogenic Ne and nearly pure 22Ne, e.g., from presolar SiC [3]. However, calculated cosmogenic Ne for CAI minerals perfectly mimics the observed trend; in particular Na-rich alteration phases shift the 21Ne/22Ne to lower values. 36Ar/38Ar is 0.7 to 4.8, thereby more altered CAIs have higher ratios. The Ar might be a mixture of chondritic cosmogenic Ar (mainly produced from Ca) and trapped Ar [3] or solar wind Ar [2], the latter supporting CAI formation in an X-wind scenario [6]. However, due to high Cl concentrations in CAIs also nearly monoisotopic 36Ar produced cosmogenically by neutron capture and beta- decay on Cl must be taken into account. Modelling Ar ratios and concentrations using only cosmogenic Ar from Ca and Cl nicely match the measured data. Thereby more Cl-rich altered CAIs show higher 36Ar/38Ar. Although the data do not principally contradict the presence of trapped Ne or Ar in CAIs they can be straightforwardly explained by cosmogenic productions mainly from Na, Ca, and Cl. {[1]} Smith et al. (1977) GCA, 41, 627-647; [2] Shukolyukov et al. (2001) Geochem. Int., 39(1), 110-125; [3] Russel et al. (1998) MAPS, 33, A132; [4] Vogel (2003) PhD-Thesis, ETH Zuerich, Switzerland; [5] Goebel et al. (1982) GCA, 46, 1777-1792; [6] Shu et al. (1997) Science, 277, 1475-1479.

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Becker, Richard H.; Pepin, Robert O.

    1994-01-01

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

  15. Trapping of Noble Gases by Radiative Association with H3 + in the Protosolar Nebula

    NASA Astrophysics Data System (ADS)

    Pauzat, F.; Bacchus-Montabonel, M.-C.; Ellinger, Y.; Mousis, O.

    2016-04-01

    The heavy noble gas deficiencies observed in Titan’s atmosphere and in comets have been proposed to be related to a sequestration process by {{{H}}}3+ in the gas phase at the early protosolar nebula. Chemical thermodynamics and astrophysics modeling are favorable to this hypothesis, as presented in preceding papers. However, there is a point still to be raised, i.e., that no dynamical study of the efficiency of the collisional processes had been performed so far. Here, we show that, apart from the expected exception of Ne, the rate constants obtained, i.e., 0.7 × 10-18, 0.5 × 10-16, and 10-16 (cm3 s-1) for Ar, Kr, and Xe, respectively, are reasonably high for such processes, particularly in the case of Kr and Xe. The temperature dependence is also considered, showing a similar behavior for all noble gases with a peak efficiency in the range 50-60 K. Globally, we can conclude that the scenario of sequestration by {{{H}}}3+ is definitively comforted by the results of our quantum dynamical treatment. This process may also be responsible of the Ar impoverishment just measured in comet 67P/Churyumov-Gerasimenko by the ROSINA mass spectrometer on board the Rosetta spacecraft.

  16. The role of grain boundaries in the storage and transport of noble gases in the mantle

    NASA Astrophysics Data System (ADS)

    Burnard, Pete G.; Demouchy, Sylvie; Delon, Rémi; Arnaud, Nicolas O.; Marrocchi, Yves; Cordier, Patrick; Addad, Ahmed

    2015-11-01

    Mantle noble gases record important and ancient isotopic heterogeneities, which fundamentally influence our understanding of mantle geodynamics, yet these heterogeneities are difficult to fully interpret without understanding the basic mechanisms of noble gas storage and transport in mantle minerals. A series of annealing experiments that mimic mantle conditions (i.e. sub-solidus with natural, polycrystalline, texturally equilibrated olivines at low noble gas partial pressures) show that intergranular interfaces (grain boundaries) are major hosts for noble gases in the mantle, and that interfaces can dramatically fractionate noble gases from their radio-parents (U + Th and K). Therefore, noble gas isotopic heterogeneities in the mantle could result from grain size variations. Fine-grained lithologies (mylonites and ultramylonites, for example) with more grain boundaries will have lower U/3He ratios (compared to a coarse grained equivalent), which, over time, will preserve higher 3He/4He ratios. As predicted by theory of points defect diffusivity, these results show that noble gas diffusion along interfaces is different from those in the grain lattice itself at low temperatures. However, for grain size relevant of the Earth's mantle, the resulting effective correlated activation energies (Ea) and pre-exponential factors (Do /a2) produce similar diffusivities at mantle temperatures for interface- and lattice-hosted helium. Therefore, grain boundaries do not significantly affect helium transport at mantle conditions and length scales.

  17. Deep-mantle-derived noble gases in metamorphic diamonds from the Kokchetav massif, Kazakhstan

    NASA Astrophysics Data System (ADS)

    Sumino, H.; Dobrzhinetskaya, L. F.; Burgess, R.; Kagi, H.

    2011-07-01

    Metamorphic diamonds from the Kokchetav massif in northern Kazakhstan are considered to have crystallized from a C-O-H fluid during ultra-high-pressure metamorphism of metasedimentary rocks subducted to 190-280 km depth. Noble gases contained in the diamonds offer great potential to constrain the noble gas state of deep mantle reservoirs. Previous studies have revealed that secondary processes during the diamond residence in the host rock drastically modified the original noble gas signature of the diamonds. However, nanometer-sized solid/fluid inclusions in the microdiamonds, which represent the former diamond-forming fluid, might preserve the noble-gas signature trapped at the time of diamond formation. We performed noble-gas analyses of the Kokchetav microdiamonds applying two gas extraction techniques: in vacuo crushing and stepwise heating. The former selectively extracts noble gases from inclusions with less noble gas extraction from the diamond lattice. Diamond crushing extracted most of the 3He, indicating that 3He occurs within inclusions trapped during diamond formation. The inclusion-hosted 3He/ 4He of (3.3-6.5) × 10 -5 is significantly higher than that of the MORB-source mantle (1.1 × 10 -5), but close to the maximum value observed in OIBs (ca. 7 × 10 -5) containing noble gases enriched in a primordial component and delivered from the deep mantle by plumes. Neon isotope ratios obtained using stepwise heating also support the presence of a plume-like component. Results show that plume-like, primordial-enriched noble gases were involved in the Kokchetav microdiamond formation, implying metasomatism of the continental lithosphere by a plume prior to its subduction, or interaction of the continental slab and a fragment of the very deep mantle. The deep-mantle-derived fragment might have been delivered to the mantle wedge of the subduction channel by large-scale mantle convection originating from a deeper lower mantle source.

  18. Santa Lucia (2008) (L6) Chondrite, a Recent Fall: Composition, Noble Gases, Nitrogen and Cosmic Ray Exposure Age

    NASA Astrophysics Data System (ADS)

    Mahajan, Ramakant R.; Varela, Maria Eugenia; Joron, Jean Louis

    2016-04-01

    The Santa Lucia (2008)—one the most recent Argentine meteorite fall, fell in San Juan province, Argentina, on 23 January 2008. Several masses (total ~6 kg) were recovered. Most are totally covered by fusion crust. The exposed interior is of light-grey colour. Chemical data [olivine (Fa24.4) and low-Ca pyroxene (En77.8 Fs20.7 Wo1.6)] indicate that Santa Luica (2008) is a member of the low iron L chondrite group, corresponding to the equilibrated petrologic type 6. The meteorite name was approved by the Nomenclature Committee (NomCom) of the Meteoritical Society (Meteoritic Bulletin, no. 97). We report about the chemical composition of the major mineral phases, its bulk trace element abundance, its noble gas and nitrogen data. The cosmic ray exposure age based on cosmogenic 3He, 21Ne, and 38Ar around 20 Ma is comparable to one peak of L chondrites. The radiogenic K-Ar age of 2.96 Ga, while the young U, Th-He are of 1.2 Ga indicates that Santa Lucia (2008) lost radiogenic 4He more recently. Low cosmogenic (22Ne/21Ne)c and absence of solar wind noble gases are consistent with irradiation in a large body. Heavy noble gases (Ar/Kr/Xe) indicated trapped gases similar to ordinary chondrites. Krypton and neon indicates irradiation in large body, implying large pre-atmospheric meteoroid.

  19. Santa Lucia (2008) (L6) Chondrite, a Recent Fall: Composition, Noble Gases, Nitrogen and Cosmic Ray Exposure Age

    NASA Astrophysics Data System (ADS)

    Mahajan, Ramakant R.; Varela, Maria Eugenia; Joron, Jean Louis

    2015-11-01

    The Santa Lucia (2008)—one the most recent Argentine meteorite fall, fell in San Juan province, Argentina, on 23 January 2008. Several masses (total ~6 kg) were recovered. Most are totally covered by fusion crust. The exposed interior is of light-grey colour. Chemical data [olivine (Fa24.4) and low-Ca pyroxene (En77.8 Fs20.7 Wo1.6)] indicate that Santa Luica (2008) is a member of the low iron L chondrite group, corresponding to the equilibrated petrologic type 6. The meteorite name was approved by the Nomenclature Committee (NomCom) of the Meteoritical Society (Meteoritic Bulletin, no. 97). We report about the chemical composition of the major mineral phases, its bulk trace element abundance, its noble gas and nitrogen data. The cosmic ray exposure age based on cosmogenic 3He, 21Ne, and 38Ar around 20 Ma is comparable to one peak of L chondrites. The radiogenic K-Ar age of 2.96 Ga, while the young U, Th-He are of 1.2 Ga indicates that Santa Lucia (2008) lost radiogenic 4He more recently. Low cosmogenic (22Ne/21Ne)c and absence of solar wind noble gases are consistent with irradiation in a large body. Heavy noble gases (Ar/Kr/Xe) indicated trapped gases similar to ordinary chondrites. Krypton and neon indicates irradiation in large body, implying large pre-atmospheric meteoroid.

  20. High-Order Multiphoton Ionization of the Noble Gases.

    NASA Astrophysics Data System (ADS)

    Perry, Michael Dale

    Ionization of an atom by the absorption of several photons from a stong electromagnetic field is considered. Specifically, the absolute yield of multiply charged ions of the noble gases, argon, krypton, and xenon produced using a well -characterized, tunable picosecond dye laser is reported as a function of both laser intensity and frequency. Theoretical models are developed to provide a quantitative interpretation of the data. The experiments were designed to investigate the influence of intermediate atomic states on the multiphoton ionization probability at intensities such that the strength of the applied field approached that of the internal atomic field. This was accomplished by measuring the ion yield over a broad range of laser intensity, 10^ {12}<=q I <=q 4times 10^{14} W/cm^2 and frequency. The laser wavelength was varied between 570 and 620 nm and the second harmonic, 285 to 310 nm. Enhancement of the yield of singly-charged krypton ions by two orders of magnitude by three-photon resonant, four-photon ionization was observed at intensities nearly two orders of magnitude above previous results. A model which considers only two atomic levels coupled by the strong field is presented and is found to be in good agreement with the experimental results. Measured values of the three-photon Rabi rate to, and the photoionization cross sections of, several excited states of Kr I are reported. In addition, even at intensities exceeding 10 ^{13} W/cm^2 , it was possible to find frequencies at which no resonant enhancement of the ionization probability could be observed. Charge states as high as Ar^ {4+}, Kr^{5+} and Xe^{6+} produced by this non-resonant multiphoton ionization were observed at the highest intensities. No evidence was found to suggest that the higher charge states are formed by the direct removal of multiple electrons. Conversely, the data is well described by a model of sequential ionization. A non-resonant, low-frequency photoionization model, similar to that of Keldysh and Reiss is presented which yields quantitative agreement with the experimental results with no adjustable parameters.

  1. 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.

  2. Determining the source and genetic fingerprint of natural gases using noble gas geochemistry: a northern Appalachian Basin case study

    USGS Publications Warehouse

    Hunt, Andrew G.; Darrah, Thomas H.; Poreda, Robert J.

    2012-01-01

    Silurian and Devonian natural gas reservoirs present within New York state represent an example of unconventional gas accumulations within the northern Appalachian Basin. These unconventional energy resources, previously thought to be noneconomically viable, have come into play following advances in drilling (i.e., horizontal drilling) and extraction (i.e., hydraulic fracturing) capabilities. Therefore, efforts to understand these and other domestic and global natural gas reserves have recently increased. The suspicion of fugitive mass migration issues within current Appalachian production fields has catalyzed the need to develop a greater understanding of the genetic grouping (source) and migrational history of natural gases in this area. We introduce new noble gas data in the context of published hydrocarbon carbon (C1,C2+) (13C) data to explore the genesis of thermogenic gases in the Appalachian Basin. This study includes natural gases from two distinct genetic groups: group 1, Upper Devonian (Marcellus shale and Canadaway Group) gases generated in situ, characterized by early mature (13C[C1  C2][13C113C2]: –9), isotopically light methane, with low (4He) (average, 1  103 cc/cc) elevated 4He/40Ar and 21Ne/40Ar (where the asterisk denotes excess radiogenic or nucleogenic production beyond the atmospheric ratio), and a variable, atmospherically (air-saturated–water) derived noble gas component; and group 2, a migratory natural gas that emanated from Lower Ordovician source rocks (i.e., most likely, Middle Ordovician Trenton or Black River group) that is currently hosted primarily in Lower Silurian sands (i.e., Medina or Clinton group) characterized by isotopically heavy, mature methane (13C[C1 – C2] [13C113C2]: 3), with high (4He) (average, 1.85  103 cc/cc) 4He/40Ar and 21Ne/40Ar near crustal production levels and elevated crustal noble gas content (enriched 4He,21Ne, 40Ar). Because the release of each crustal noble gas (i.e., He, Ne, Ar) from mineral grains in the shale matrix is regulated by temperature, natural gases obtain and retain a record of the thermal conditions of the source rock. Therefore, noble gases constitute a valuable technique for distinguishing the genetic source and post-genetic processes of natural gases.

  3. The noble gases: how their electronegativity and hardness determines their chemistry.

    PubMed

    Furtado, Jonathan; De Proft, Frank; Geerlings, Paul

    2015-02-26

    The establishment of an internally consistent scale of noble gas electronegativities is a long-standing problem. In the present study, the problem is attacked via the Mulliken definition, which in recent years gained widespread use to its natural appearance in the context of conceptual density functional theory. Basic ingredients of this scale are the electron affinity and the ionization potential. Whereas the latter can be computed routinely, the instability of the anion makes the judicious choice of computational technique for evaluating electron affinities much more tricky. We opted for Puiatti's approach, extrapolating the energy of high ε solvent stabilized anions to the ε = 1 (gas phase) case. The results give negative electron affinity values, monotonically increasing (except for helium which is an outlier in most of the story) to almost zero at eka-radon in agreement with high level calculations. The stability of the B3LYP results is successfully tested both via improving the level of theory (CCSD(T)) and expanding the basis set. Combined with the ionization energies (in good agreement with experiment), an electronegativity scale is obtained displaying (1) a monotonic decrease of χ when going down the periodic table, (2) top values not for the noble gases but for the halogens, as opposed to most (extrapolation) procedures of existing scales, invariably placing the noble gases on top, and (3) noble gases having electronegativities close to the chalcogens. In the accompanying hardness scale (hardly, if ever, discussed in the literature) the noble gases turn out to be by far the farthest the hardest elements, again with a continuous decrease with increasing Z. Combining χ value of the halogens and the noble gases the Ng(δ+)F(δ-) bond polarity emerging from ab initio calculations naturally emerges. In conclusion, the chemistry of the noble gases is for a large part determined by their extreme hardness, equivalent to a high resistance to change in its electronic population coupled to their high electronegativity. PMID:25662361

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  6. Method and apparatus for measuring purity of noble gases

    DOEpatents

    Austin, Robert

    2008-04-01

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

  7. 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.

  8. 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.

  9. 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.

    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.

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

    SciTech Connect

    Mazor, E.; Truesdell, A.H.

    1981-01-01

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

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

    PubMed

    Coltice, Nicolas; Ricard, Yanick

    2002-11-15

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

  12. Palaeotemperature reconstruction from noble gases in ground water taking into account equilibration with entrapped air

    PubMed

    Aeschbach-Hertig; Peeters; Beyerle; Kipfer

    2000-06-29

    Noble-gas concentrations in ground water have been used as a proxy for past air temperatures, but the accuracy of this approach has been limited by the existence of a temperature-independent component of the noble gases in ground water, termed 'excess air' whose origin and composition is poorly understood. In particular, the evidence from noble gases in a Brazilian aquifer for a cooling of more than 5 C in tropical America during the Last Glacial Maximum has been called into question. Here we propose a model for dissolved gases in ground water, which describes the formation of excess air by equilibration of ground water with entrapped air in quasi-saturated soils. Our model predicts previously unexplained noble-gas data sets, including the concentration of atmospheric helium, and yields consistent results for the non-atmospheric helium isotopes that are used for dating ground water. Using this model of excess air, we re-evaluate the use of noble gases from ground water for reconstructing past temperatures. Our results corroborate the inferred cooling in Brazil during the Last Glacial Maximum, and indicate that even larger cooling took place at mid-latitudes. PMID:10890441

  13. Seeded optical breakdown of molecular and noble gases

    SciTech Connect

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

    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.

  14. Multidiffusion mechanisms for noble gases (He, Ne, Ar) in silicate glasses and melts in the transition temperature domain: Implications for glass polymerization

    NASA Astrophysics Data System (ADS)

    Amalberti, Julien; Burnard, Pete; Laporte, Didier; Tissandier, Laurent; Neuville, Daniel R.

    2016-01-01

    Noble gases are ideal probes to study the structure of silicate glasses and melts as the modifications of the silicate network induced by the incorporation of noble gases are negligible. In addition, there are systematic variations in noble gas atomic radii and several noble gas isotopes with which the influence of the network itself on diffusion may be investigated. Noble gases are therefore ideally suited to constrain the time scales of magma degassing and cooling. In order to document noble gas diffusion behavior in silicate glass, we measured the diffusivities of three noble gases (4He, 20Ne and 40Ar) and the isotopic diffusivities of two Ar isotopes (36Ar and 40Ar) in two synthetic basaltic glasses (G1 and G2; 20Ne and 36Ar were only measured in sample G1). These new diffusion results are used to re-interpret time scales of the acquisition of fractionated atmospheric noble gas signatures in pumices. The noble gas bearing glasses were synthesized by exposing the liquids to high noble gas partial pressures at high temperature and pressure (1750-1770 K and 1.2 GPa) in a piston-cylinder apparatus. Diffusivities were measured by step heating the glasses between 423 and 1198 K and measuring the fraction of gas released at each temperature step by noble gas mass spectrometry. In addition we measured the viscosity of G1 between 996 and 1072 K in order to determine the precise glass transition temperature and to estimate network relaxation time scales. The results indicate that, to a first order, that the smaller the size of the diffusing atom, the greater its diffusivity at a given temperature: D(He) > D(Ne) > D(Ar) at constant T. Significantly, the diffusivities of the noble gases in the glasses investigated do not display simple Arrhenian behavior: there are well-defined departures from Arrhenian behavior which occur at lower temperatures for He than for Ne or Ar. We propose that the non-Arrhenian behavior of noble gases can be explained by structural modifications of the silicate network itself as the glass transition temperature is approached: as the available free volume (available site for diffusive jumps) is modified, noble gas diffusion is no longer solely temperature-activated but also becomes sensitive to the kinetics of network rearrangements. The non-Arrhenian behavior of noble gas diffusion close to Tg is well described by a modified Vogel-Tammann-Fulcher (VTF) equation: Finally, our step heating diffusion experiments suggest that at T close to Tg, noble gas isotopes may suffer kinetic fractionation at a degree larger than that predicted by Graham's law. In the case of 40Ar and 36Ar, the traditional assumption based on Graham's law is that the ratio D40Ar/D36Ar should be equal to 0.95 (the square root of the ratio of the mass of 36Ar over the mass of 40Ar). In our experiment with glass G1, D40Ar/D36Ar rapidly decreased with decreasing temperature, from near unity (0.98 ± 0.14) at T > 1040 K to 0.76 when close to Tg (T = 1003 K). Replicate experiments are needed to confirm the strong kinetic fractionation of heavy noble gases close to the transition temperature.

  15. 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

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

    SciTech Connect

    Jo, Sungkwon; Hoon Lee, Dae; Seok Kang, Woo; Song, Young-Hoon

    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.

  17. Noble gases in the Bells (C2) and Sharps (H3) chondrites

    NASA Technical Reports Server (NTRS)

    Zadnik, M. G.

    1985-01-01

    The Bells and Sharps chondrites are of uncertain classification in virtue of their mineralogical and chemical peculiarities, prompting the present elemental and isotopic measurements of the noble gases in them, together with such quantities derivable from them as cosmogenic exposure and gas retention ages, as well as primordial gas contents. The radiogenic and, above all, the cosmogenic gases link Bells to the C2 group, while Sharps is found to lie in the second largest peak of the H-chondrite distribution.

  18. Noble gases in vent water from the Juan de Fuca Ridge

    SciTech Connect

    Kennedy, B.M. )

    1988-07-01

    Hydrothermal vent fluids collected with the DSRV Alvin from the southern limb of the Juan de Fuca Ridge are chemically unique, having chloride concentrations {approximately}2 times ambient seawater. The same fluids contain noble gases in relative abundances like 2{degree}C air-saturated seawater, the expected recharge composition. However, the absolute noble gas abundances are depleted by {approximately}30% relative to seawater. The combination of very high chloride and moderately depleted noble gases appears to require formation of a Cl-rich, gas-free brine by phase separation. This brine is mixed with recharge seawater at temperatures in excess of {approximately}340{degree}C and, therefore, deep in the hydrothermal system.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  20. Noble gases in 60009-60010 drive tube samples - Trapped gases and irradiation history. [of lunar soil

    NASA Technical Reports Server (NTRS)

    Bogard, D. D.; Hirsch, W. C.

    1976-01-01

    Concentrations and isotopic composition of noble gases are reported for grain size separates: nine soils from the 60010-60009 double drive tube, two soils from the 60007 drill core section, and surface soil 65501. Data are reported on concentrations of solar wind gases, surface-correlated gases (involving solar wind and lunar atmosphere), surface maturity indices, cosmogenic gases, possible soil mixing, and irradiation by cosmic rays. Good correlation is found between solar wind gases in 60009 soils and such surface maturity indices as petrographic agglutinates, magnetic soil fraction, and fine-grained iron. Cosmogenic He-3, Ne-21, Ar-38, Kr-80, and Xe-126 all display close correlations in the drive tube soils.

  1. A generic biokinetic model for noble gases with application to radon.

    PubMed

    Leggett, Rich; Marsh, James; Gregoratto, Demetrio; Blanchardon, Eric

    2013-06-01

    To facilitate the estimation of radiation doses from intake of radionuclides, the International Commission on Radiological Protection (ICRP) publishes dose coefficients (dose per unit intake) based on reference biokinetic and dosimetric models. The ICRP generally has not provided biokinetic models or dose coefficients for intake of noble gases, but plans to provide such information for (222)Rn and other important radioisotopes of noble gases in a forthcoming series of reports on occupational intake of radionuclides (OIR). This paper proposes a generic biokinetic model framework for noble gases and develops parameter values for radon. The framework is tailored to applications in radiation protection and is consistent with a physiologically based biokinetic modelling scheme adopted for the OIR series. Parameter values for a noble gas are based largely on a blood flow model and physical laws governing transfer of a non-reactive and soluble gas between materials. Model predictions for radon are shown to be consistent with results of controlled studies of its biokinetics in human subjects. PMID:23612507

  2. Noble gases in the Martian meteorite Northwest Africa 2737: A new chassignite signature

    NASA Astrophysics Data System (ADS)

    Marty, Bernard; Heber, Veronika S.; Grimberg, Ansgar; Wieler, Rainer; Barrat, Jean-Alix

    2006-05-01

    We report noble gas data for the second chassignite, Northwest Africa (NWA) 2737, which was recently found in the Moroccan desert. The cosmic ray exposure (CRE) age based on cosmogenic 3He, 21Ne, and 38Ar around 10-11 Ma is comparable to the CRE ages of Chassigny and the nakhlites and indicates ejection of meteorites belonging to these two families during a discrete event, or a suite of discrete events having occurred in a restricted interval of time. In contrast, U-Th/He and K/Ar ages <0.5 Ga are in the range of radiometric ages of shergottites, despite a Sm-Nd signature comparable to that of Chassigny and the nakhlites (Misawa et al. 2005). Overall, the noble gas signature of NWA 2737 resembles that of shergottites rather than that of Chassigny and the nakhlites: NWA 2737 does not contain, in detectable amount, the solar-like xenon found in Chassigny and thought to characterize the Martian mantle nor apparently fission xenon from 244Pu, which is abundant in Chassigny and some of the nakhlites. In contrast, NWA 2737 contains Martian atmospheric noble gases trapped in amounts comparable to those found in shergottite impact glasses. The loss of Martian mantle noble gases, together with the trapping of Martian atmospheric gases, could have occurred during assimilation of Martian surface components, or more likely during shock metamorphism, which is recorded in the petrology of this meteorite.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Pohl, Robert O.

    2003-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2001-10-01

    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 krypton and xenon for the two-photon excitation of atomic hydrogen at 205.1 nm, nitrogen at 206.6 nm, and oxygen at 225.5 nm. We investigated these excitations by TALIF in order to determine the atomic data required for this calibration. The radiative lifetimes of the excited states and the quenching coefficients for collisions with several important species were obtained from time resolved measurements. The relevant ratios of the two-photon excitation cross-sections were determined from comparative measurements with known densities. The atomic reference densities were generated in a flow-tube reactor with the aid of titration methods.

  6. A comprehensive study of noble gases and nitrogen in "Hypatia", a diamond-rich pebble from SW Egypt

    NASA Astrophysics Data System (ADS)

    Avice, Guillaume; Meier, Matthias M. M.; Marty, Bernard; Wieler, Rainer; Kramers, Jan D.; Langenhorst, Falko; Cartigny, Pierre; Maden, Colin; Zimmermann, Laurent; Andreoli, Marco A. G.

    2015-12-01

    This is a follow-up study of a work by Kramers et al. (2013) on a very unusual diamond-rich rock fragment found in the area of south west Egypt in the south-western side of the Libyan Desert Glass strewn field. This pebble, called Hypatia, is composed of almost pure carbon. Transmission Electron Microscopy (TEM) and X-ray diffraction (XRD) results reveal that Hypatia is mainly made of defect-rich diamond containing lonsdaleite and multiple deformation bands. These characteristics are compatible with an impact origin on Earth and/or in space. We also analyzed concentrations and isotopic compositions of all five noble gases and nitrogen in several ∼mg sized Hypatia samples. These data confirm the conclusion by Kramers et al. (2013) that Hypatia is extra-terrestrial. The sample is relatively rich in trapped noble gases with an isotopic composition being close to the Q component found in many types of meteorites. 40Ar/36Ar ratios in individual steps are as low as 0.4 ± 0.3. Cosmic-ray produced "cosmogenic" 21Ne is present in concentrations corresponding to a nominal cosmic-ray exposure (CRE) age of roughly 0.1 Myr if produced in a typical meter-sized meteoroid. Such an atypically low nominal CRE age suggests high shielding in a considerably larger body. In addition to the Xe-Q composition, an excess of radiogenic 129Xe (from the decay of short-lived radioactive 129I) is observed (129Xe /132Xe = 1.18 + / - 0.03). Two isotopically distinct N components are present, an isotopically heavy component (δ15N ∼ + 20 ‰) released at low temperatures and a major isotopically light component (δ15N ∼ - 110 ‰) at higher temperatures. This disequilibrium in N suggests that the diamonds in Hypatia were formed in space rather than upon impact on Earth (δN15atm = 0 ‰). All our data are broadly consistent with concentrations and isotopic compositions of noble gases in at least three different types of carbon-rich meteoritic materials: carbon-rich veins in ureilites, graphite in acapulcoites/lodranites and graphite nodules in iron meteorites. However, Hypatia does not seem to be directly related to any of these materials, but may have sampled a similar cosmochemical reservoir. Our study does not confirm the presence of exotic noble gases (e.g. G component) that led Kramers et al. (2013) to propose that Hypatia is a remnant of a comet nucleus that impacted the Earth.

  7. Abundance and isotopic composition of noble gases in metal and graphite of the Bohumilitz IAB iron meteorite

    NASA Astrophysics Data System (ADS)

    Maruoka, Teruyuki; Matsuda, Jun-Ichi; Kurat, Gero

    2001-05-01

    Abundances and isotopic compositions of noble gases in metal and graphite of the Bohumilitz IAB iron meteorite were measured. The abundance ratios of spallogenic components in metal reveal a 3He deficiency which is due to the diffusive loss of parent isotopes, i.e., tritium (Tilles, 1963; Schultz, 1967). The diffusive loss likely has been induced by thermal heating by the Sun during cosmic ray exposure (( 160 My; Lavielle et al., 1999). Thermal process such as impact-induced partial loss may have affected the isotopic composition of spallogenic Ne. The 129Xe/131Xe ratio of cosmogenic components in the metal indicates an enhanced production of epi-thermal neutrons. The abundance ratios of spallogenic components in the graphite reveal that it contained small amounts of metal and silicates. The isotopic composition of heavy noble gases in graphite itself was obtained from graphite treated with HF/HCl. The isotopic composition of the etched graphite shows that it contains two types of primordial Xe, i.e., Q-Xe and El Taco Xe. The isotopic heterogeneity preserved in the Bohumilitz graphite indicates that the Bohumilitz graphite did not experience any high(temperature event and, consequently, must have been emplaced into the metal at subsolidus temperatures. This situation is incompatible with an igneous model as well as the impact melting models for the IAB-IIICD iron meteorites as proposed by Choi et al. (1995) and Wasson et al. (1980).

  8. Cosmogenic 10Be and Noble Gases in Diogenites

    NASA Astrophysics Data System (ADS)

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

    1993-07-01

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

  9. Helium solubility in mica and mechanisms for deep transport of noble gases in subduction zones

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Parman, S. W.; Kelley, S. P.; Cooper, R. F.

    2012-12-01

    We have experimentally determined helium solubility in mica to explore possible transport mechanisms of noble gases in subduction zones. Helium solubility in single crystals of muscovite and F-phlogopite investigated is relatively high, ~1 [He]/PHe (ppm/kbar). This solubility is approximately two orders of magnitude greater than values recently measured for olivine [1], and similar to values recently measured for amphibole with a low density of unoccupied ring sites [2]. Helium was dissolved into the micas by subjecting them to a high pressure noble gas atmosphere (1.26-1.48 He-Ne-Ar kbar) at moderate temperatures (450-700 C), allowing the micas to diffusively equilibrate with the imposed helium fugacity. Diffusion of Ne and Ar is too slow in both micas at the explored conditions to quantify their solubility. Experiments were conducted using a TZM gas pressure medium apparatus (Brown University). Analysis was completed by noble gas LA-MS (Open University, UK). Muscovite (dioctehedral) and F-phlogopite (trioctehedral) represent the two basic structural groups of micas, suggesting micas stabilized at higher pressures and temperatures, such as phengite, can provide a relatively deep transport mechanism for noble gases delivered to subduction zones. Thus, phengite may play a role in explaining atmospheric signatures in mantle derived noble gases [e.g.3,4]. 1. Heber, V. S., Brooker, R. A., Kelley, S. P. & Wood, B. J., GCA, 71, 1041-1061 2. Jackson C.R.M, Kelley S.P., Parman S.W., Cooper R.F., Goldschmidt 2012 Abstract 3. Holland, G. & Ballentine, C. J., Nature 441, 186-191 4. Mukhopadhyay, S.. Nature 486, 101-104

  10. Incorporation of Solar Noble Gases from a Nebula-Derived Atmosphere During Magma Ocean Cooling

    NASA Technical Reports Server (NTRS)

    Woolum, D. S.; Cassen, P.; Wasserburg, G. J.; Porcelli, D.; DeVincenzi, Donald (Technical Monitor)

    1998-01-01

    The presence of solar noble gases in the deep interior of the Earth is inferred from the Ne isotopic compositions of MORB (Mid-ocean Ridge Basalts) and OIB (Oceanic Island Basalt); Ar data may also consistent with a solar component in the deep mantle. Models of the transport and distribution of noble gases in the earth's mantle allow for the presence of solar Ar/Ne and Xe/Ne ratios and permit the calculation of lower mantle noble gas concentrations. These mantle data and models also indicate that the Earth suffered early (0.7 to 2 x 10(exp 8) yr) and large (greater than 99 percent) losses of noble gases from the interior, a result previously concluded for atmospheric Xe. We have pursued the suggestion that solar noble gases were incorporated in the forming Earth from a massive, nebula-derived atmosphere which promoted large-scale melting, so that gases from this atmosphere dissolved in the magma ocean and were mixed downward. Models of a primitive atmosphere captured from the solar nebula and supported by accretion luminosity indicate that pressures at the Earth's surface were adequate (and largely more than the required 100 Atm) to dissolve sufficient gases. We have calculated the coupled evolution of the magma ocean and the overlying atmosphere under conditions corresponding to the cessation (or severe attenuation) of the sustaining accretion luminosity, prior to the complete removal of the solar nebula. Such a condition was likely to obtain, for instance, when most of the unaccumulated mass resided in large bodies which were only sporadically accreted. The luminosity supporting the atmosphere is then that provided by the cooling Earth, consideration of which sets a lower limit to the time required to solidify the mantle and terminate the incorporation of atmospheric gases within it. In our initial calculations, we have fixed the nebula temperature at To = 300K, a value likely to be appropriate for nebular temperatures at lAU in the early planet-building epoch. We treated the background (nebula) pressure as an adjustable, time-dependent parameter. Additional information is contained within the original extended abstract.

  11. Lunar meteorite Yamato-983885: Noble gases, nitrogen and cosmic ray exposure history

    NASA Astrophysics Data System (ADS)

    Mahajan, Ramakant R.

    2015-11-01

    Noble gases and nitrogen have been in lunar meteorite from antartcica: the polymict regolith breccias, Yamato-983885 (hereafter Y-983885). Y-983885 has highest concentration of trapped noble gases (Ar, Kr, and Xe) among all the lunar meteorites and returned lunar samples. Noble gases and nitrogen abundances measured in two samples of the lunar meteorite Y-983885. The concentration of trapped noble gases in Y-983885 (A) are, 20Ne=3.69×10-3, 36Ar=12.6×10-4, 84kr=8.57×10-7 and 132Xe=1.63×10-7 ccSTP/g. The cosmic-ray exposure ages for Y-983885 are thus calculated to be T21 (A)=1592±232 Ma and T21 (B)=574±85 Ma for 2π geometry (using production rates as per Hohenberg et al., 1978 and bulk composition). The exposure ages of samples A and B differ, indicating that they have undergone different exposure scenarios on the lunar surface. The different irradiation ages (T21 (A)=1592±232 Ma and T21 (B)=574±85 Ma) indicates that the regolith material which constitutes the meteorite Y-983885 resided at different shielding depths on lunar surface before agglomeration into the final meteorite. Exposure ages calculated using end member compositon like norite, basalt, tractolite (1947 to 1365 and 711 to 455 for A and B respectively) indicates clearly that the two samples A and B has undergone different exposure on Moon. The 20Ne/22Ne ratio of 13.60±0.01 in temperature step 400 °C of Y-983885 (A) demonstrate a clear retention of solar wind signature in this meteorite. The presence of high contents of trapped solar wind gases indicates that Y-983885 consists of mature lunar regolith material. Variable amounts of solar gases as well as cosmogenic noble gases indicate that Y-983885 (A and B) is compacted from several fragments that were exposed at the surface and/or at various depths in the regolith, before becoming part of Y-983885.

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

    SciTech Connect

    Goodson, Boyd M.

    1999-12-01

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

  13. Terrestrial nitrogen and noble gases in lunar soils.

    PubMed

    Ozima, M; Seki, K; Terada, N; Miura, Y N; Podosek, F A; Shinagawa, H

    2005-08-01

    The nitrogen in lunar soils is correlated to the surface and therefore clearly implanted from outside. The straightforward interpretation is that the nitrogen is implanted by the solar wind, but this explanation has difficulties accounting for both the abundance of nitrogen and a variation of the order of 30 per cent in the 15N/14N ratio. Here we propose that most of the nitrogen and some of the other volatile elements in lunar soils may actually have come from the Earth's atmosphere rather than the solar wind. We infer that this hypothesis is quantitatively reasonable if the escape of atmospheric gases, and implantation into lunar soil grains, occurred at a time when the Earth had essentially no geomagnetic field. Thus, evidence preserved in lunar soils might be useful in constraining when the geomagnetic field first appeared. This hypothesis could be tested by examination of lunar farside soils, which should lack the terrestrial component. PMID:16079836

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  15. 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

    2012-10-03

    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.

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

    SciTech Connect

    Lazanu, Ionel; Lazanu, Sorina E-mail: lazanu@infim.ro

    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.

  17. 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.; Williams, R. J. R.; Blesener, K.; Atoyan, L.; Cahill, A.; Hoyt, C.; Potter, W.; 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.

  18. 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.

  19. The solubility of noble gases in crude oil at 25-100°C

    USGS Publications Warehouse

    Kharaka, Yousif K.; Specht, Daniel J.

    1988-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Swindle, T. D.

    1988-01-01

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

  1. 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.; Mousis, O.; Ali Dib, M. E-mail: ellinger@lct.jussieu.fr E-mail: olivier.mousis@obs-besancon.fr

    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.

  2. Gas-phase Sequestration of Noble Gases in the Protosolar Nebula: Possible Consequences on the Outer Solar System Composition

    NASA Astrophysics Data System (ADS)

    Pauzat, F.; Ellinger, Y.; Mousis, O.; Ali-Dib, M.; Ozgurel, O.

    2013-11-01

    We address the problem of the sequestration of Ar, Kr, and Xe by H_3^+ in the gas-phase conditions encountered during the cooling of protoplanetary disks when H_3^+ 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_5^+, H2O, and H3O+ present in the protosolar nebula. Apart from the fact that H_3^+ complexes formed with heavy noble gases are found to be by far much more stable than those formed with He or H2O, we show that H2D+ and H3O+, both products of the reactions of H_3^+ with HD and H2O, can also be efficient trapping agents for Ar, Kr, and Xe. Meanwhile, the abundance profile of H_3^+ 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_3^+ at earlier epochs than those corresponding to their trapping in planetesimals. We find that H_3^+ 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.

  3. Noble gases in presolar diamonds I: Three distinct components and their implications for diamond origins

    NASA Technical Reports Server (NTRS)

    Huss, Gary R.; Lewis, Roy S.

    1994-01-01

    High-purity separates of presolar diamond were prepared from 14 primitive chondrites from 7 compositional groups. Their noble gases were measured using stepped pyrolysis. Three distinct noble gas components are present in diamonds, HL, P3, and P6, each of which is found to consist of five noble gases. P3, released between 200 C and 900 C, has a 'planetary' elemental abundance pattern and roughly 'normal' isotopic ratios. HL, consisting of isotopically anomalous Xe-HL and Kr-H, Ar with high Ar-38/Ar-36, and most of the gas making up Ne-A2 and He-A, is released between 1100 C and 1600 C. HL has 'planetary' elemental ratios, except that it has much more He and Ne than other known 'planetary' components. HL gases are carried in the bulk diamonds, not in some trace phase. P6 has a slightly higher median release temperature than HL and is not cleanly separated from HL by stepped pyrolysis. Our data suggest that P6 has roughly 'normal' isotopic compositions and 'planetary' elemental ratios. Both P3 and P6 seem to be isotopically distinct from P1, the dominant 'planetary' noble-gas component in primitive chondrites. Release characteristics suggest that HL and P6 are sited in different carriers within the diamond fractions, while P3 may be sited near the surfaces of the diamonds. We find no evidence of separability of Xe-H and Xe-L or other isotopic variations in the HL component. However, because approximately 10(exp 10) diamonds are required to measure a Xe composition, a lack of isotopic variability does not constrain diamonds to come from a single source. In fact, the high abundance of diamonds in primitive chondrites and the presence of at least three distinct noble-gas components strongly suggest that diamonds originated in many sources. Relative abundances of noble-gas components in diamonds correlate with degree of thermal processing, indicating that all meteorites sampled essentially the same mixture of diamonds. That mixture was probably inherited from the Sun's parent molecular cloud.

  4. Role of van der Waals forces in the diffraction of noble gases from metal surfaces

    NASA Astrophysics Data System (ADS)

    del Cueto, M.; Muzas, A. S.; Füchsel, G.; Gatti, F.; Martín, F.; Díaz, C.

    2016-02-01

    The role of van der Waals (vdW) forces in the description of scattering processes of noble gases from metal surfaces is currently under debate. Although features of the potential energy surface such as anticorrugation or adsorption energies are sometimes found to be well described by standard density functional theory (DFT), the performance of DFT to describe diffraction spectra may rely on the accuracy of the vdW functionals used. To analyze the precise role of these vdW forces in noble gas diffraction by metal surfaces, we have thoroughly studied the case of Ne/Ru(0001), for which accurate experimental results are available. We have carried out classical and quantum dynamics calculations by using DFT-based potentials that account for the effect of vdW interactions at different levels of accuracy. From the comparison of our results with experimental data, we conclude that the inclusion of vdW effects is crucial to properly describe diffraction of noble gases from metal surfaces. We show that among the vdW-DFT functionals available in the literature, not all of them can be used to accurately describe this process.

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  6. 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.

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

    NASA Astrophysics Data System (ADS)

    Swindle, T. D.; Masarik, J.; Kollár, D.; Kim, K. J.; Reedy, R. C.

    2005-03-01

    The age of the surface of Europa is probably tens of Myr or less, but is poorly constrained. Two different geochronology schemes could potentially be applied to near-surface samples to provide far more precise ages. First, the surface salts apparently contain enough potassium to make potassium-argon dating feasible. Second, the bombardment of the surface with both galactic cosmic rays and protons trapped within the jovian magnetosphere will cause nuclear reactions that can lead to measurable buildups of cosmogenic noble gases, which can be used to determine both cosmic-ray exposure ages and erosion, deposition, or mixing rates for surface modification. The major differences between Europa's salt-rich ice and the rocks (meteorites, lunar samples and terrestrial rocks) in which cosmogenic noble gases are normally measured are that the abundance of target elements for nuclear reactions creating neon and argon are lower (because of the high water content), but neutron-capture reactions, particularly 35Cl( n, γ) 36Cl( β-) 36Ar, are enhanced because of the thermalizing effects of the water. As well as presenting calculations of noble gas production near the surface of Europa, we also show that the measurements required to determine ages are within reach of technology in the near future, if an instrument can be landed on the surface of Europa.

  8. 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.

  9. Purely physical separation of a small fraction of the Allende meteorite that is highly enriched in noble gases

    NASA Astrophysics Data System (ADS)

    Matsuda, Jun-Ichi; Amari, Sachiko; Nagao, Keisuke

    1999-01-01

    Fine material which floats during freeze-thaw disaggregation of the Allende meteorite is greatly enriched in noble gases compared to the bulk meteorite. Not only the elemental concentrations but also most isotopic ratios of the noble gases in this fraction strongly suggest that this material is very similar to the gas-rich carbonaceous residue isolated from the bulk meteorite by chemical treatment. The only significant difference in noble gas signature between our separated fraction and the chemical residues is that the 129Xe/132Xe ratio in the former is significantly lower than that in the latter, suggesting re-adsorption of 129Xe released from the dissolved minerals during the chemical treatment. This is the first time that a gas-rich residue of a meteorite has been separated by a purely physical method alone. We also show that noble gases in phase Q and presolar diamond may be separable physically, although both are closely associated.

  10. Noble gases in solar-gas-rich and solar-gas-free polymict breccias

    NASA Astrophysics Data System (ADS)

    Takahito, Osawa; Keisuke, Nagao

    Polymict breccias are useful for research of solar activity because some preserve plenty of solar noble gases implanted during asteroidal formation processes. In this study, noble gas compositions of Antarctic and non-Antarctic polymict breccias were determined using laser gas-extraction and stepwise pyrolysis techniques. Of the polymict breccias measured in this work, 5 of 18 were identified as gas-rich meteorites (regolith breccias) and 4 of those 5 are H chondrites. The high population of gas-rich H chondrites compared with L and LL chondrites was presumably related to the depth of regolith formed on each parent body. It is notable that the major part of polymict breccias did not have solar noble gases. Noble gas analyses with stepwise heating method were done for 11 polymict breccias. Gas-rich meteorites have high concentrations of solar-derived He and Ne, which were released at relatively low temperature steps. Cosmogenic nuclides were comparatively dominant at high temperature steps. Five sources determined the observed Ar isotopic compositions. The components were: atmospheric, radiogenic, solar wind (SW), solar energetic particles (SEP), and cosmogenic. In contrast, Ne isotopic compositions of most regolith breccias can be explained simply by three-component mixing, such as SW, SEP, and cosmogenic. Indications of primordial trapped components were observed only in Willard (b), in which carbonaceous chondrite clasts were discovered previously. Cosmic-ray exposure ages were calculated from excess ^3He, ^(21)Ne, and ^(38)Ar. Regolith breccias did not have systematically longer ages than gas-poor samples, indicating that the parent body exposure ages of the meteorites on the order of tens of millions of years at most.

  11. The quest for regolithic howardites. Part 2: Surface origins highlighted by noble gases

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    We report noble gas data of helium (He), neon (Ne), argon (Ar), krypton (Kr) and xenon (Xe), cosmic ray exposure (CRE) ages and nominal gas retention (K-Ar, U-Th-He) ages for seven howardites (CRE 01400, EET 87513, EET 87518, EET 99400, GRO 95535, GRO 95602, SAN 03472), in continuing research to identify regolithic samples, and better understand the vestan regolith. In our previous work, we found little correlation between suggested regolith parameters of Ni > 300 μg/g, Al2O3 8-9 wt% and eucrite/diogenite (E:D) ratio of 2:1 (Warren et al., 2009), and trapped solar wind (SW), fractionated solar wind (FSW) or planetary noble gas components (from impacted material) - noble gas indicators of a regolithic origin. Here, we have expanded our data set to include samples outside of these parameters to further explore composition, and the differences in Ni content as indicators for the presence of non-Vesta material. In addition, our sample set includes two potentially paired meteorites from the GRO suite. Finally, in our petrographic studies, the samples selected showed no evidence for carbonaceous chondrite fragments, which should reduce the effect of “contamination” by planetary noble gas components, and will allow us to better identify SW/FSW components, where present. Of the samples studied here, three howardites GRO 95535, GRO 95602 and EET 87513 show evidence for a regolithic origin, with both isotopic and element noble gas ratios clearly pointing to the presence of trapped components similar to SW/FSW or planetary. The two GRO howardites, GRO 95535 and GRO 95602, show similar noble gas ratios to our previously defined SW/FSW dominated regolithic group (LEW 85313 and MET 00423), suggesting a surface origin for these samples. However, interestingly, the GRO samples show vastly different cosmogenic noble gas abundances, and thus different CRE ages, which suggests that they are not paired. For howardite EET 87513, the data hint to the presence of CM-material, with a neon release pattern similar to our defined planetary/FSW dominated regolithic group (CM-rich samples PRA 04401, SCO 06040). Our petrological investigations found no evidence for CM fragments within EET 87513, though a single clast was reported previously (Buchanan et al., 1993). Aside from the Ne release pattern, the remaining noble gas data show more similarity with SW/FSW components. The remaining four howardites CRE 01400, EET 87518, EET 99400, and SAN 03472 and are dominated by cosmogenic noble gases, and show no evidence for a regolithic origin. Our data suggest that a CM-composition is likely present in all samples to some degree, but that this can be overprinted by SW components or cosmogenic components obtained in situ on the vestan surface or during transit to Earth respectively. The presence of CM material is an important parameter for understanding the evolution of Vesta’s surface. While we have uncovered three further regolithic howardites (∼13 regolithic total, of ∼41 analysed), further noble gas analysis of HED meteorites is needed to not only determine regolithic origins, but to better characterise the abundance of carbonaceous chondrite material and its effect on the noble gas signatures of such samples.

  12. Cylindrically converging radiative shocks in noble gases driven by the MAGPIE pulsed-power device

    NASA Astrophysics Data System (ADS)

    Burdiak, Guy; Lebedev, S.; Harvey-Thompson, Adam; Swadling, G.; Suzuki-Vidal, F.; Skidmore, J.; Suttle, L.; Bennet, M.; Hall, G.; Pickworth, L.; de Grouchy, P.; Bland, S.; Niasse, N.; Rodriguez, R.; Gil, J.; Espinosa, G.

    2013-10-01

    Experimental data from gas-filled cylindrical liner z-pinch experiments are presented. The current discharge from the MAGPIE pulsed-power device at Imperial College London (1.4 MA,240 ns) is applied to a thin walled (80 μm) Al tube with a static gas-fill inside (initial gas density 10-5 g/cc). The system is used to drive cylindrically converging strong shock waves (Us = 20 km/s) into different gases. Axial diagnostics include interferometry, optical streak photography and time gated, spatially resolved optical spectroscopy. The experimental geometry is nominally uniform along the diagnostic line of sight and in addition the shock waves show a high degree of azimuthal symmetry. This allows determination of the radial dependence of axially averaged plasma parameters (ne,Te) . The spectroscopy diagnostic is used to determine the temperature profile across the shock (in the precursor and post-shock regions) in different noble gases. Comparisons are made between experimental temperature and electron density profiles and the 1D radiation-MHD code HELIOS-CR. In addition, varying degrees of shock stability are seen in different noble gases. These observations will be briefly compared to cooling function calculations and analytical stability models.

  13. Evaluation of theoretical cross sections for electron scattering from noble gases for plasma modeling

    NASA Astrophysics Data System (ADS)

    Pitchford, Leanne; Zatsarinny, O.; Bartschat, K.; Fursa, D. V.; Bray, I.; Alves, L. L.; Biagi, S.

    2013-09-01

    Can state-of-the-art theory now provide complete sets of cross sections for electron scattering from noble gases suitable for use in Boltzmann calculations of swarm parameters and to the accuracy required for plasma modeling? The answer is a qualified ``yes'' for He, Ne, and Ar, but ``not yet'' for Kr and Xe. Purely theoretical cross section sets for electron scattering from these species are presently available on the LXCat website in the BRAY database for He (calculated using the convergent close-coupling technique, formulated in momentum space) and in the BSR database for the other rare gases (obtained with a convergent B-spline R-matrix with pseudo-states method, formulated in coordinated space). Although significant differences occasionally appear in some of the cross sections between experiment and theory, the calculated ionization rate coefficients as a function of reduced electric field strength, E/N, for He, Ne and Ar agree with experiment to within a few percent for the three lighter noble gases. This work is supported, in part, by the United States National Science Foundation.

  14. 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.

  15. Postcollisional mafic igneous rocks record recycling of noble gases by deep subduction of the continental crust

    NASA Astrophysics Data System (ADS)

    Dai, Li-Qun; Zheng, Yong-Fei; He, Huai-Yu; Zhao, Zi-Fu

    2016-05-01

    Recycling of noble gases from crustal rocks into the mantle is indicated not only by oceanic basalts and mantle xenoliths, but also by ultrahigh-pressure metamorphic rocks in collisional orogens. It is intriguing whether noble gases in continental crust were recycled into the mantle by deep subduction of the continental crust to mantle depths. Here we firstly report the He, Ne and Ar isotopic compositions of pyroxene from postcollisional mafic igneous rocks in the Dabie orogen, China. The results show that the pyroxene separates from the mafic rocks have low 3He/4He ratios of 0.002 to 1.8 Ra and air-like Ne isotope compositions. Furthermore, the pyroxene exhibits low 40Ar/36Ar ratios of 393.6 to 1599.8, close to those of the air. In combination with whole-rock geochemistry it is found that pyroxene 3He/4He ratios are correlated with whole-rock (La/Yb)N and Sr/Y ratios, εNd(t) values and MgO contents. These observations demonstrate the mass transfer from the deeply subducted continental crust to the overlying mantle wedge, recording the source mixing between the crust-derived melt and the mantle peridotite in the continental subduction zone. A direct addition of the crustal He via crust-derived melt to the mantle leads to the extremely low 3He/4He ratios in the orogenic lithospheric mantle, and the dissolved atmospheric Ar and Ne in the subducted supracrustal rocks results in the air-like Ar and Ne isotope ratios. Therefore, the noble gas isotopic signatures of supracrustal rocks were carried into the mantle by the continental deep subduction to subarc depths and then transferred to the postcollisional mafic igneous rocks via the melt-peridotite reaction at the slab-mantle interface in a continental subduction channel. Our finding firstly establishes the slab-mantle interaction model for recycling of supracrustal noble gases in the continental subduction zone.

  16. High power external cavity laser diode arrays for the generation of hyperpolarized noble gases

    NASA Astrophysics Data System (ADS)

    Blasche, Gregory Paul

    Hyperpolarized noble gas magnetic resonance imaging promises to be a useful medical diagnostic tool due to its ability to image airways and brain function. A current limitation to widespread use is the time needed to generate gas quantities large enough for clinical patient imaging. Here I investigate line-narrowing of laser diode arrays in order to optimize the generation of hyperpolarized noble gases. Hyperpolarized noble gases are nuclear spin-½ isotopes that are polarized externally to have a large excess population of metastable spin up nuclei. When inhaled and imaged, they provide a novel tool for scientific studies and medical diagnosis in the human body. The gases are generated through a spin-exchange process via the spin-conserving hyperfine interaction of noble gas nuclei and optically pumped alkali metals. The net amount of polarized gas is limited by the optical power which is absorbed by the alkali metals as this is the first stage in the spin-exchange process. Laser diode arrays are typically used because they have a high available power for relatively low cost. Unfortunately, they are optically inefficient due to the factor of twenty larger inherent linewidth relative to the pressure broadened absorption linewidth of the alkali metal. In order to increase the efficiency of the system, I have designed and built an external cavity around the laser diode array consisting of a diffraction grating which acts as a wavelength dependent mirror tuned to the alkali metal rubidium absorption frequency. This causes the laser to operate solely at the desired wavelength, reducing the linewidth. External cavities have long been used for single element laser diodes. I extend this technique to laser diode arrays by imaging the diodes onto the grating using a set of imaging lenses forming individual cavities. I discuss the limitations on the power and linewidth achievable due to the optics of the cavity, as well as limitations caused by non-uniform heating effects. Finally, I present measurements of the nuclear polarization and absorption for Helium using our line-narrowed laser system and will compare and contrast the benefits of the line-narrowed system over the fiber-coupled laser diode arrays currently being used.

  17. 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

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

    PubMed Central

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

    2015-01-01

    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

  19. Noble gases and nitrogen released from lunar soils by acid etching

    NASA Astrophysics Data System (ADS)

    Rider, Paul E.; Pepin, Robert O.; Becker, Richard H.

    1995-12-01

    A stepwise acid-etching technique similar to the closed system stepwise etching (CSSE) method developed at ETH Zurich was used to examine the solar wind reservoirs of lunar soil grains. Samples were treated with weak acids (H 2O, H 2SO 3) to facilitate the release of the most shallowly implanted gases. Noble gas abundances and isotopic compositions, including Kr and Xe in some cases, and a few nitrogen data were obtained for mineral or grain-size separates of three lunar soils (plagioclase from 60051, pyroxene from 75081, and <25 ym bulk 79035). The 60051 plagioclase grains, considered to be a possibly unique resource for determining the modern-day solar wind composition, show unusually low contents of solar wind He, Ne, and particularly Ar, but do not otherwise possess any characteristics clearly attributable to a modem-day solar wind exposure. Initial water and acid treatments of the grains, however, release an apparently pure SEP component. The 75081 pyroxene and the size separate of bulk 79035 both yield Kr and Xe compositions in initial etch steps that are characteristic of undiffused solar wind, significantly increasing the database for measurements of solar wind Kr and Xe where possible laboratory thermal diffusion and fractionation effects are not a concern. Pyroxene in particular appears to be a suitable alternative to ilmenite for the purpose of making measurements of this kind. Nitrogen release by acid etching is not at present quantitative, and while it appears possible to obtain reasonable isotopic ratios for solar wind N, we are unable to use the technique to determine solar nitrogen to noble gas ratios. Light noble gases in all three soil separates, other than the aforementioned behavior of 60051, appear to behave in accord with expectations based on acid-etching analyses performed by the Züirich group.

  20. Noble Gases Analyses of Samples Synthesized at High P and T in a Multi Anvil Press Device: Protocol and Implications

    NASA Astrophysics Data System (ADS)

    Bonnefoy, B.; Andrault, D.; Moreira, M.; Bolfan-Casanova, N.

    2007-12-01

    Noble gases (He-Ne-Ar-Kr-Xe) in mantle-derived samples allow an undisputable tracing of different sources of materials. Concerning the deep mantle part, the study of noble gases suggests that a "primordial" component (which is non or partially degassed) exists. Nevertheless, this conclusion is challenged by several observations, both geophysical and geochemical, suggesting that contrariwise the mantle is now totally depleted, degassed or renewed by convection. Furthermore, the lack of experimental data disables quantitative modelling of geochemistry processes. It is still unknown how much the fractionations are dependent on the conditions on pressure, temperature and chemical composition in the mantle. Recent studies [1-3] suggest a more incompatible behavior for noble gases in comparison to their parent element (K for Ar, U + Th for He) in very specific conditions of pressure, temperature, and chemical composition. Nevertheless, those studies focus on only particular compositions or pressures or only one single noble gas. No exhaustive studies (of all nobles gases at different pressures, temperatures and compositions) were accomplished on this subject so far. We set up a new experimental protocol allowing the analyses of rare gases in samples synthesized under mantle conditions, at high pressures and temperatures. This new protocol associates the use of a gas loading device [4], a multi-anvil press device (INSU MAP, Clermont-Ferrand, France), a laser ablation coupled to mass- spectrometer for the noble gases analysis (excimer laser, λ = 193 nm), and a 3D profilometry device to quantify the amount of ablated material. We will present an application of these methods on the noble gases partitioning between solid and liquid natural phases in the 3-5 GPa pressure range and for temperature of 1400 to 1600°C. [1] E.M. Chamorro, R.A Brooker, J.-A Wartho, B.J. Wodd, S.P. Kelley and J.D. Blundy. Ar and K partitioning between clinopyroxene and silicate melt to 8 GPa. Geochimica et Cosmochimica Acta, 66: 507-519, 2002. [2] S.W. Parman, M.D. Kurz, S.R. Hart and T. L. Groove. Helium solubility in olivine and implication for high 3He/4He in ocean island basalts. Nature, 437: 1140-1143, 2005. [3] V.S. Heber, R.A. Brooker, S.P Kelley and B.J. Wood. Crystal-melt partitioning of nobles gases (helium, neon, argon, krypton and xenon) for olivine and clinopyroxene. Geochimica et Cosmochimica Acta, 71: 1041-1061. [4] S.L. Boetcher, Q. Guo and A. Montana. A simple device for loading gases in high-pressure experiments. American Mineralogist, 74: 1383-1384, 1989.

  1. Interstellar Diamond: The Analysis Results for Carbon, Nitrogen, and Noble Gases in Different Grain-Size Fractions

    NASA Astrophysics Data System (ADS)

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

    The content and isotopic composition of carbon, nitrogen, and noble gases in different grain-size fractions of interstellar diamond from the Efremovka chondrite have been established for the first time. Using these data as the base, we have found the following. (a) All isotopically anomalous components of C, N, and noble gases and the characteristic features of the release of these components, revealed for bulk samples of dia- mond, are also inherent in diamond fractions. At the same time, the fractions differ drastically in the proportion of the isotopically anomalous and normal components and in the elemental ratios of noble gases. (b) Mixing of two components for carbon, as well as for nitrogen (one of these components is in the surface layer of diamond and enriched with 13C and 15N), results in the observed variations of isotopic composition of these elements released in the stepped combustion of diamond fractions. (c) The nitrogen-content variations during diamond- grain oxidation are most probably determined by the diffusion loss of nitrogen, which occurred mainly before the integration of diamond with the material of the chondrite-parent bodies (for example, at the period of dia- mond formation or in the second heating). (d) The combination of the process of implantation of noble gases into diamond grains in at least two events, with the following diffusion loss, led to the heterogeneous distribu- tion of noble gases in the grain volume. The revealed peculiarities of distribution and isotopic content of C, N, and noble gases in the fractions of interstellar diamond have been invoked for establishing the main stages of its formation during an extremely nonequilibrium process.

  2. Momentum transfer cross sections for the heavy noble gases

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    We present momentum transfer cross sections for elastic electron scattering from argon, krypton and xenon atoms over the energy range from zero to 1 keV. These have been calculated using the Dirac equations with a relativistic complex optical potential which includes polarization of the target atom by the incident electron and allows for the absorption of some of the incident electron flux into channels representing excitation and ionization of the atom. In order to aid in plasma modelling calculations, we provide simple analytic fits to these cross sections as well as to the elastic scattering cross sections. Comparisons are made with previous experimental and theoretical results.

  3. 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.

  4. Cosmogenic and trapped noble gases in individual chondrules: Clues to chondrule formation

    NASA Astrophysics Data System (ADS)

    Das, J. P.; Murty, S. V. S.

    2009-12-01

    We studied the elemental and isotopic abundances of noble gases (He, Ne, Ar in most cases, and Kr, Xe also in some cases) in individual chondrules separated from six ordinary, two enstatite, and two carbonaceous chondrites. Most chondrules show detectable amounts of trapped 20Ne and 36Ar, and the ratio (36Ar/20Ne)t (from ordinary and carbonaceous chondrites) suggests that HL and Q are the two major trapped components. A different trend between (36Ar/20Ne)t and trapped 36Ar is observed for chondrules in enstatite chondrites indicating a different environment and/or mechanism for their formation compared to chondrules in ordinary and carbonaceous chondrites. We found that a chondrule from Dhajala chondrite (DH-11) shows the presence of solar-type noble gases, as suggested by the (36Ar/20Ne)t ratio, Ne-isotopic composition, and excess of 4He. Cosmic-ray exposure (CRE) ages of most chondrules are similar to their host chondrites. A few chondrules show higher CRE age compared to their host, suggesting that some chondrules and/or precursors of chondrules have received cosmic ray irradiation before accreting to their parent body. Among these chondrules, DH-11 (with solar trapped gases) and a chondrule from Murray chondrite (MRY-1) also have lower values of (21Ne/22Ne)c, indicative of SCR contribution. However, such evidences are sporadic and indicate that chondrule formation event may have erased such excess irradiation records by solar wind and SCR in most chondrules. These results support the nebular environment for chondrule formation.

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

    DOE PAGESBeta

    Moskovitz, Yevgeny; Yang, Hui

    2015-01-08

    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

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

    SciTech Connect

    Moskovitz, Yevgeny; Yang, Hui

    2015-01-08

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

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

    PubMed

    Moskovitz, Yevgeny; Yang, Hui

    2015-03-21

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

  8. 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.

  9. Mean annual temperature of New Zealand during the last glacial period derived from dissolved noble gases

    NASA Astrophysics Data System (ADS)

    Seltzer, A. M.; Stute, M.; Morgenstern, U.; Stewart, M. K.; Schaefer, J. M.

    2014-12-01

    Determining the magnitude of warming since the last glacial maximum (LGM) is fundamental to our understanding of glacial-interglacial climate dynamics, but is currently poorly quantified in certain regions of the world. In the southern mid-latitudes, temperature reconstructions based on paleoceanographic and terrestrial proxies vary widely and the mean annual temperature during the LGM of the region remains an ongoing debate. This study presents a reconstruction of LGM mean annual surface temperature in New Zealand using groundwater noble gas paleothermometry. The concentration of dissolved noble gases in groundwater depends on a dissolved-gas phase equilibrium reached at a distinct temperature, pressure, and salinity. Measurement of dissolved neon, argon, krypton, and xenon concentrations in paleogroundwater enables the reconstruction of mean annual surface temperature at the time of recharge. Initial results show an average last glacial period (LGP) mean annual surface temperature of about 4°C to 6°C cooler than today. Because the wells sampled have long (often >100 meters) screened intervals allowing for inflow of groundwater across a wide vertical profile, 'mixing' between LGP and modern waters influences the noble gas temperatures of LGP paleogroundwater samples. We therefore interpret the lowest temperature measured in this study, ~6°C cooler than today, as our best LGM mean-annual temperature estimate in New Zealand. This value is larger than that of ~3°C, based on a number of paleoceanographic LGM temperature reconstructions in the vicinity of Australia and New Zealand derived from foraminiferal assemblages. However, this reconstructed mean annual temperature falls within the high end of a range of estimates from alkenones and foraminifera Mg/Ca-based studies, which have suggested LGM temperatures of 4-7°C cooler than present, and agrees closely with glacial-snowline based mean summer temperature estimates of ~6-7°C.

  10. The quest for regolithic howardites. Part 1: Two trends uncovered using noble gases

    NASA Astrophysics Data System (ADS)

    Cartwright, J. A.; Ott, U.; Mittlefehldt, D. W.; Herrin, J. S.; Herrmann, S.; Mertzman, S. A.; Mertzman, K. R.; Peng, Z. X.; Quinn, J. E.

    2013-03-01

    We report noble gas data (helium (He), neon (Ne), argon (Ar), krypton (Kr) and xenon (Xe)), nominal gas retention ages (K-Ar, U-Th-He) and cosmic ray exposure (CRE) ages for the ten howardites EET 83376, EET 99408, LEW 85313, MET 00423, MET 96500, PCA 02066, PRA 04401, QUE 94200, QUE 97002, and SCO 06040, in research to better understand the regolith of the HED parent body - Vesta - through a combined petrological, compositional and noble gas study. Our main aim is to determine which howardites are truly regolithic - as defined by the presence of solar noble gas components (e.g. solar wind (SW), fractionated solar wind (FSW)) and/or by the presence of planetary components (e.g. Q, HL) associated with foreign clasts of carbonaceous chondrite material within the breccias. Of our ten howardites, four (LEW 85313, MET 00423, PRA 04401 and SCO 06040) show evidence for a regolithic origin, with noble gas ratios indicating the presence of trapped components. Howardites PRA 04401 and SCO 06040 contain significant amounts of CM type carbonaceous chondrite material, and these samples are dominated by a planetary component similar to that observed in CM meteorites Murchison and Maribo. Overall, we find evidence for two regolithic groups with different release trends: (1) SW/FSW component dominated howardites (LEW 85313 and MET 00423), where SW/FSW is dominant at low temperature releases, and less pronounced at higher temperatures; (2) Planetary component dominated howardites (PRA 04401 and SCO 06040) that also contain SW/FSW - the planetary component is associated with incorporated carbonaceous chondrite material, and is dominant at the mid-temperature release. The remaining six howardites EET 83376, EET 99408, MET 96500, PCA 02066, QUE 94200, and QUE 97002, are dominated by cosmogenic noble gases, and are not considered regolithic. Previous work by Warren et al. (2009) suggested that high siderophile element contents (specifically nickel (Ni) > 300 μg/g) were a regolith indicator for howardites, in addition to restricted Al2O3 contents (8-9 wt.%) representing a eucrite/diogenite mixing ratio of 2:1 as indicative of an ancient well-mixed regolith. These parameters were based on five 'gas-rich' howardites. However, we find no obvious correlation between these parameters and SW/FSW or planetary noble gas content in our howardite samples. We conclude that howardite regolith parameters are not as simple as those defined by Warren et al. (2009), where three of the five howardites used contained foreign CM material, which may have caused a bias in their defined parameters. We conclude that sideophile abundances alone cannot be used to determine the regolithic nature of a sample: noble gas analysis remains a key parameter, where it is important to distinguish between planetary-dominated and SW-dominated regolithic howardites.

  11. Trapping of xenon in ice - Implications for the origin of the earth's noble gases

    NASA Technical Reports Server (NTRS)

    Wacker, J. F.; Anders, E.

    1984-01-01

    Although the earth's atmosphere contains Ne, Ar, and Kr in about C1,2-chondrite proportions, Xe is depleted about 20-fold. To test the suggestion that the 'missing' Xe is trapped in Antarctic ice, distribution coefficients for Xe in artifically formed frost at -20 to -60 C were measured, using Xe-127 tracer. The values are 0.098 + or - 0.004 cc STP/g atm for trapping and less than 5 cc STP/g atm for trapping plus adsorption. If these results are representative of natural ice, then the Antarctic ice cap contains less than 1 percent of the atmospheric Xe inventory, or not greater than about 0.001 the amount needed for a C1,2-chondrite pattern. Two possibilities remain for the 'missing' Xe, both on the premise that the earth's noble gases, along with other volatiles, came from chondritic material: (1) xenon is preferentially retained in the mantle and lower crust, due to the strong affinity of Xe for clean silicate surfaces and amorphous carbon; and (2) the source material of the earth's volatiles had high, relatively unfractionated, Ar/Xe and Kr/Xe ratios, like the non-carbonaceous noble gas carriers in C3O and E-chondrites.

  12. Tandem mass spectrometry of endohedral complexes of C{sub 60} and C{sub 70} with some noble gases

    SciTech Connect

    Giblin, D.; Gross, M.L.; Saunders, M.; Jimenez-Vazquez, H.; Cross, R.J.; Mroczkowski, S.; Poreda, R.J.

    1994-12-31

    It has been show that C{sub 60} and C{sup 70} form endohedral complexes upon high-energy collisions with target gases such as He and Ne. Recently, a high-pressure method for preparing the endohedral complexes of C{sub 60} and C{sub 70} with noble gases has been developed, which has made possible the production of macroscopic quantities of the complexes. This preliminary study reports results of high-energy CAD of these complexes.

  13. 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

  14. 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.

  15. Observation of threshold effects in positron scattering from the noble gases.

    PubMed

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

    2010-08-13

    Channel coupling is a phenomenon that has been investigated for many scattering processes, and is responsible for the formation of cusps or steps in the cross sections for open scattering channels at, or near, the onset of a new scattering channel. It has long been speculated that the opening of the positronium formation channel may lead to the formation of such cusp features in the elastic positron scattering cross section. In this work, elastic scattering of positrons has been measured in the region of the positronium formation threshold for the noble gases He-Xe. Cusplike behavior is observed and, while the features which are observed appear broad, they represent a magnitude of between 4 and 15% of the total elastic cross section. No evidence is found of any other features in this region, at least within the uncertainty of the present data, discounting the possibility of scattering resonances. PMID:20868040

  16. Multiple electron emission from noble gases colliding with proton beams, including postcollisional effects

    NASA Astrophysics Data System (ADS)

    Galassi, M. E.; Rivarola, R. D.; Fainstein, P. D.

    2007-05-01

    The process of multiple electron ionization of Ne and Ar noble gases produced by impact of proton beams is studied in the framework of the independent-electron model. The role played by different mechanisms is analyzed, including intershell Auger and intrashell Coster-Kronig electron emission, which follow the production of vacancies due to direct interaction of the projectile with the target electrons. The present results, obtained with the continuum distorted wave eikonal initial state (CDW-EIS) approximation, confirm previous predictions given by a different theoretical model. Semiempirical approximations are introduced by using analytical single-ionization probabilities with adjustable parameters determined from CDW-EIS total cross sections. The small computational time required to calculate multiple ionization cross sections with these semiempirical approximations and the good agreement found with existing experimental data and with results obtained with more elaborated theoretical models make them good candidates to study electron emission from complex targets.

  17. Integrated Stokes Parameters for Impact Excitation of Noble Gases by Spin-Polarized Electrons.

    NASA Astrophysics Data System (ADS)

    Zeman, Vlado; Bartschat, Klaus

    1997-04-01

    We have applied the Breit-Pauli R-matrix method [1] to model electron impact excitation of the [np^5(n+1)p] states in noble gases. Besides the total and differential cross sections, we have calculated the polarization of the light emitted in the subsequent optical decay to the [np^5(n+1)s] states, integrated over the projectile scattering angle. The results will be compared with recent experimental data [2--4]. 1. K.A. Berrington, W.B. Eissner and P.H. Norrington, Comp. Phys. 1. Commun 92, 290 (1995) 2. C. Noren and J.W. McConkey, Phys. Rev. A53, 3253 (1996) 3. T.J. Gay, J.E. Furst, K.W. Tramtham and W.M.K.P. Wijayaratna, 3. Phys. Rev. A53, 1623 (1996) 4. D.H. Yu, P.A. Hayes and J.F. Williams (1997), 4. private communication

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  19. 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.

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  1. 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.

  2. The Preparation and Use of Short Half-Lived Radioactive Noble Gases in Nuclear Medicine.

    NASA Astrophysics Data System (ADS)

    Dahl, J. Robert

    1990-01-01

    Radioisotopes of noble gases have been widely used for biomedical studies for many years, in particular for lung function studies and for studies of patients with coronary artery disease. ^{rm 79m}Kr (T_{1over2 } = 50s) emits 130 keV gamma rays in 27% of its disintegrations, ^{rm 127m }Xe (T_{1over2} = 69.2s) emits a 172.5 keV gamma ray in 38% of its disintegrations and a 124.8 keV gamma ray in 69% of its disintegrations and ^{19} Ne (T_{1over2} = 17.1s) decays 99.1% by positron emission. The energy of the ^{rm 79m}Kr gamma ray and of the more abundant ^{ rm 127m}Xe 124.8 keV gamma ray is sufficiently close to the 140.5 keV gamma energy of ^ {rm 99m}Tc to provide images of similar quality using present equipment. Neon-19 offers potential for ventilation studies and regional blood flow measurements using positron emission tomography (PET). The increasing number of small medical cyclotrons provides the alternative of utilizing very short half-lived radioactive noble gases such as ^{rm 79m }Kr, ^{rm 127m} Xe, and ^{19}Ne. A procedure has been developed for preparing these radionuclides by bombarding aqueous solutions of alkali metal halides with 14 MeV protons, using a helium sweep gas to remove the products as they are produced. A target design, production rates, methods of quality control, delivery and use of the ^{rm 79m}Kr and ^{rm 127m}Xe are given. A new method for preparing ^ {19}Ne is presented.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  4. Sedimentary halogens and noble gases within Western Antarctic xenoliths: Implications of extensive volatile recycling to the sub continental lithospheric mantle

    NASA Astrophysics Data System (ADS)

    Broadley, Michael W.; Ballentine, Chris J.; Chavrit, Déborah; Dallai, Luigi; Burgess, Ray

    2016-03-01

    Recycling of marine volatiles back into the mantle at subduction zones has a profound, yet poorly constrained impact on the geochemical evolution of the Earth's mantle. Here we present a combined noble gas and halogen study on mantle xenoliths from the Western Antarctic Rift System (WARS) to better understand the flux of subducted volatiles to the sub continental lithospheric mantle (SCLM) and assess the impact this has on mantle chemistry. The xenoliths are extremely enriched in the heavy halogens (Br and I), with I concentrations up to 1 ppm and maximum measured I/Cl ratios (85.2 × 10-3) being ∼2000 times greater than mid ocean ridge basalts (MORB). The Br/Cl and I/Cl ratios of the xenoliths span a range from MORB-like ratios to values similar to marine pore fluids and serpentinites, whilst the 84Kr/36Ar and 130Xe/36Ar ratios range from modern atmosphere to oceanic sediments. This indicates that marine derived volatiles have been incorporated into the SCLM during an episode of subduction related metasomatism. Helium isotopic analysis of the xenoliths show average 3He/4He ratios of 7.5 ± 0.5 RA (where RA is the 3He/4He ratio of air = 1.39 × 10-6), similar to that of MORB. The 3He/4He ratios within the xenoliths are higher than expected for the xenoliths originating from the SCLM which has been extensively modified by the addition of subducted volatiles, indicating that the SCLM beneath the WARS must have seen a secondary alteration from the infiltration and rise of asthenospheric fluids/melts as a consequence of rifting and lithospheric thinning. Noble gases and halogens within these xenoliths have recorded past episodes of volatile interaction within the SCLM and can be used to reconstruct a tectonic history of the WARS. Marine halogen and noble gas signatures within the SCLM xenoliths provide evidence for the introduction and retention of recycled volatiles within the SCLM by subduction related metasomatism, signifying that not all volatiles that survive subduction are mixed efficiently through the convecting mantle. The global SCLM therefore represents a potentially important reservoir for the long term residence of subducted volatiles.

  5. 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.

  6. 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.

  7. Regularities And Irregularities Of The Stark Parameters For Single Ionized Noble Gases

    NASA Astrophysics Data System (ADS)

    Peláez, R. J.; Djurovic, S.; Cirišan, M.; Aparicio, J. A.; Mar S.

    2010-07-01

    Spectroscopy of ionized noble gases has a great importance for the laboratory and astrophysical plasmas. Generally, spectra of inert gases are important for many physics areas, for example laser physics, fusion diagnostics, photoelectron spectroscopy, collision physics, astrophysics etc. Stark halfwidths as well as shifts of spectral lines are usually employed for plasma diagnostic purposes. For example atomic data of argon krypton and xenon will be useful for the spectral diagnostic of ITER. In addition, the software used for stellar atmosphere simulation like TMAP, and SMART require a large amount of atomic and spectroscopic data. Availability of these parameters will be useful for a further development of stellar atmosphere and evolution models. Stark parameters data of spectral lines can also be useful for verification of theoretical calculations and investigation of regularities and systematic trends of these parameters within a multiplet, supermultiplet or transition array. In the last years, different trends and regularities of Stark parameters (halwidths and shifts of spectral lines) have been analyzed. The conditions related with atomic structure of the element as well as plasma conditions are responsible for regular or irregular behaviors of the Stark parameters. The absence of very close perturbing levels makes Ne II as a good candidate for analysis of the regularities. Other two considered elements Kr II and Xe II with complex spectra present strong perturbations and in some cases an irregularities in Stark parameters appear. In this work we analyze the influence of the perturbations to Stark parameters within the multiplets.

  8. 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.

  9. 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...

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

    SciTech Connect

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

    2011-08-07

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

  11. 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.

  12. Absolute cross sections for projectile electron loss accompanied by target multiple ionization in collisions of He+ with noble gases

    NASA Astrophysics Data System (ADS)

    Santos, A. C. F.; Sigaud, G. M.; Melo, W. S.; Sant'Anna, M. M.; Montenegro, E. C.

    2011-02-01

    Absolute cross sections for projectile electron loss accompanied by target multiple ionization in collisions between He+ ions and noble gases have been measured for energies between 1.0 and 3.5 MeV. The data have been compared with other absolute cross sections that exist in the literature for the same projectile, and with calculations for the screening mode (nucleus-electron interaction) using both perturbative (plane-wave Born approximation (PWBA)) and non-perturbative (extended classical-impulse free-collision model, sudden approximation and coupled-channel method) approaches, and for the antiscreening mode (electron-electron interaction) within the PWBA. The energy dependence of the average number of active electrons for the antiscreening has been described by means of a simple function, which is 'universal' for noble gases but projectile dependent. A previously developed method has been employed to obtain the number of active electrons for each target subshell in the high-velocity regime.

  13. Optimized Mie potentials for phase equilibria: Application to noble gases and their mixtures with n-alkanes

    NASA Astrophysics Data System (ADS)

    Mick, Jason R.; Soroush Barhaghi, Mohammad; Jackman, Brock; Rushaidat, Kamel; Schwiebert, Loren; Potoff, Jeffrey J.

    2015-09-01

    Transferrable force fields, based on n-6 Mie potentials, are presented for noble gases. By tuning the repulsive exponent, ni, it is possible to simultaneously reproduce experimental saturated liquid densities and vapor pressures with high accuracy, from the normal boiling point to the critical point. Vapor-liquid coexistence curves for pure fluids are calculated using histogram reweighting Monte Carlo simulations in the grand canonical ensemble. For all noble gases, saturated liquid densities and vapor pressures are reproduced to within 1% and 4% of experiment, respectively. Radial distribution functions, extracted from NVT and NPT Monte Carlo simulations, are in similarly excellent agreement with experimental data. The transferability of the optimized force fields is assessed through calculations of binary mixture vapor-liquid equilibria. These mixtures include argon + krypton, krypton + xenon, methane + krypton, methane + xenon, krypton + ethane, and xenon + ethane. For all mixtures, excellent agreement with experiment is achieved without the introduction of any binary interaction parameters or multi-body interactions.

  14. Optimized Mie potentials for phase equilibria: Application to noble gases and their mixtures with n-alkanes.

    PubMed

    Mick, Jason R; Soroush Barhaghi, Mohammad; Jackman, Brock; Rushaidat, Kamel; Schwiebert, Loren; Potoff, Jeffrey J

    2015-09-21

    Transferrable force fields, based on n-6 Mie potentials, are presented for noble gases. By tuning the repulsive exponent, ni, it is possible to simultaneously reproduce experimental saturated liquid densities and vapor pressures with high accuracy, from the normal boiling point to the critical point. Vapor-liquid coexistence curves for pure fluids are calculated using histogram reweighting Monte Carlo simulations in the grand canonical ensemble. For all noble gases, saturated liquid densities and vapor pressures are reproduced to within 1% and 4% of experiment, respectively. Radial distribution functions, extracted from NVT and NPT Monte Carlo simulations, are in similarly excellent agreement with experimental data. The transferability of the optimized force fields is assessed through calculations of binary mixture vapor-liquid equilibria. These mixtures include argon + krypton, krypton + xenon, methane + krypton, methane + xenon, krypton + ethane, and xenon + ethane. For all mixtures, excellent agreement with experiment is achieved without the introduction of any binary interaction parameters or multi-body interactions. PMID:26395716

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

    SciTech Connect

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

    2013-11-14

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

  16. 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.

  17. Shock Compression Response of the Light Noble Gases: Neon and Helium

    NASA Astrophysics Data System (ADS)

    Root, Seth; Shulenburger, Luke; Cochrane, Kyle; Lopez, Andrew; Shelton, Keegan; Villalva, Jose; Mattsson, Thomas

    2015-06-01

    Understanding material behavior at extreme conditions is important to a wide range of processes in planetary astrophysics and inertial confinement fusion. Modeling the high pressure - high temperature processes requires robust equations of state (EOS). For many materials, EOS models have been developed using low-pressure Hugoniot data. Assumptions are made to extrapolate the EOS models to Mbar pressure regimes, leading to different model behavior at extreme conditions. In this work, we examine the high pressure response of the light noble gases: neon and helium in the multi-Mbar regime. We perform a series of shock compression experiments using Sandia's Z-Machine on cryogenically cooled liquids of Ne (26 K) and He (2.2 K) to measure the Hugoniot and reshock states. In parallel, we use density functional theory methods to calculate the Hugoniot and reshock states. The experiments validated the DFT simulations and the combined experimental and simulation results are used to assess the EOS models. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Securities Administration under Contract No. DE-AC04-94AL85000.

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

    PubMed

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

    2013-11-14

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

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

    NASA Astrophysics Data System (ADS)

    Pressyanov, Dobromir S.

    2013-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Glein, Christopher R.

    2015-04-01

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

  1. Ancient carbon and noble gas fractionation. [in carbonaceous meteorites and terrestrial kerogen

    NASA Technical Reports Server (NTRS)

    Frick, U.; Chang, S.

    1977-01-01

    Noble gases in ancient terrestrial kerogen and meteoritic carbonaceous residues are compared in terms of their elemental fractionation with respect to atmospheric and the cosmic reservoirs, respectively. Fractionation factors for the heavy noble gases are almost identical in both types of samples. Therefore, some features of the interaction between carbon phases and noble gases in very different environments of origin appear to be similar. These findings underscore the plausibility of the meteoritic carbonaceous residues as a noble gas carrier and as a novel vehicle for achieving the elemental fractionation required to derive the planetary noble gas pattern from cosmic abundances.

  2. Noble gases preserve history of retentive continental crust in the Bravo Dome natural CO2 field, New Mexico

    NASA Astrophysics Data System (ADS)

    Sathaye, Kiran J.; Smye, Andrew J.; Jordan, Jacob S.; Hesse, Marc A.

    2016-06-01

    Budgets of 4He and 40Ar provide constraints on the chemical evolution of the solid Earth and atmosphere. Although continental crust accounts for the majority of 4He and 40Ar degassed from the Earth, degassing mechanisms are subject to scholarly debate. Here we provide a constraint on crustal degassing by comparing the noble gases accumulated in the Bravo Dome natural CO2 reservoir, New Mexico USA, with the radiogenic production in the underlying crust. A detailed geological model of the reservoir is used to provide absolute abundances and geostatistical uncertainty of 4He, 40Ar, 21Ne, 20Ne, 36Ar, and 84Kr. The present-day production rate of crustal radiogenic 4He and 40Ar, henceforth referred to as 4He* and 40Ar*, is estimated using the basement composition, surface and mantle heat flow, and seismic estimates of crustal density. After subtracting mantle and atmospheric contributions, the reservoir contains less than 0.02% of the radiogenic production in the underlying crust. This shows unequivocally that radiogenic noble gases are effectively retained in cratonic continental crust over millennial timescales. This also requires that approximately 1.5 Gt of mantle derived CO2 migrated through the crust without mobilizing the crustally accumulated gases. This observation suggests transport along a localized fracture network. Therefore, the retention of noble gases in stable crystalline continental crust allows shallow accumulations of radiogenic gases to record tectonic history. At Bravo Dome, the crustal 4He*/40Ar* ratio is one fifth of the expected crustal production ratio, recording the preferential release of 4He during the Ancestral Rocky Mountain orogeny, 300 Ma.

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

    NASA Astrophysics Data System (ADS)

    Marty, B.

    2013-12-01

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

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

    PubMed

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

    2014-09-30

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

  5. 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, δ13C-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

  6. 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.

  7. Martian Noble Gases in Recently Found Shergottites, Nakhlites, and Breccia Northwest Africa 8114

    NASA Astrophysics Data System (ADS)

    Busemann, H.; Seiler, S.; Wieler, R.; Kuga, M.; Maden, C.; Irving, A. J.; Clay, P. L.; Joy, K. H.

    2015-07-01

    New noble gas data for several recently found martian meteorites will be presented to determine cosmic-ray exposure ages and source pairing. The presence of trapped (atmospheric) components and discrepancies to earlier data sets will be discussed.

  8. Origins of volatile elements (H, C, N, noble gases) on Earth and Mars in light of recent results from the ROSETTA cometary mission

    NASA Astrophysics Data System (ADS)

    Marty, Bernard; Avice, Guillaume; Sano, Yuji; Altwegg, Kathrin; Balsiger, Hans; Hässig, Myrtha; Morbidelli, Alessandro; Mousis, Olivier; Rubin, Martin

    2016-05-01

    Recent measurements of the volatile composition of the coma of Comet 67P/Churyumov-Gerasimenko (hereafter 67P) allow constraints to be set on the origin of volatile elements (water, carbon, nitrogen, noble gases) in inner planets' atmospheres. Analyses by the ROSINA mass spectrometry system onboard the Rosetta spacecraft indicate that 67P ice has a D/H ratio three times that of the ocean value (Altwegg et al., 2015) and contains significant amounts of N2, CO, CO2, and importantly, argon (Balsiger et al., 2015). Here we establish a model of cometary composition based on literature data and the ROSINA measurements. From mass balance calculations, and provided that 67P is representative of the cometary ice reservoir, we conclude that the contribution of cometary volatiles to the Earth's inventory was minor for water (≤1%), carbon (≤1%), and nitrogen species (a few % at most). However, cometary contributions to the terrestrial atmosphere may have been significant for the noble gases. They could have taken place towards the end of the main building stages of the Earth, after the Moon-forming impact and during either a late veneer episode or, more probably, the Terrestrial Late Heavy Bombardment around 4.0-3.8 billion years (Ga) ago. Contributions from the outer solar system via cometary bodies could account for the dichotomy of the noble gas isotope compositions, in particular xenon, between the mantle and the atmosphere. A mass balance based on 36Ar and organics suggests that the amount of prebiotic material delivered by comets could have been quite considerable - equivalent to the present-day mass of the biosphere. On Mars, several of the isotopic signatures of surface volatiles (notably the high D/H ratios) are clearly indicative of atmospheric escape processes. Nevertheless, we suggest that cometary contributions after the major atmospheric escape events, e.g., during a Martian Late Heavy Bombardment towards the end of the Noachian era, could account for the Martian elemental C/N/36Ar ratios, solar-like krypton isotope composition and high 15N/14N ratios. Taken together, these observations are consistent with the volatiles of Earth and Mars being trapped initially from the nebular gas and local accreting material, then progressively added to by contributions from wet bodies from increasing heliocentric distances. Overall, no unified scenario can account for all of the characteristics of the inner planet atmospheres. Advances in this domain will require precise analysis of the elemental and isotopic compositions of comets and therefore await a cometary sample return mission.

  9. 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.

  10. Effect of residual gases in high vacuum on the energy-level alignment at noble metal/organic interfaces

    SciTech Connect

    Helander, M. G.; Wang, Z. B.; Lu, Z. H.

    2011-10-31

    The energy-level alignment at metal/organic interfaces has traditionally been studied using ultraviolet photoelectron spectroscopy (UPS) in ultra-high vacuum (UHV). However, since most devices are fabricated in high vacuum (HV), these studies do not accurately reflect the interfaces in real devices. We demonstrate, using UPS measurements of samples prepared in HV and UHV and current-voltage measurements of devices prepared in HV, that the small amounts of residual gases that are adsorbed on the surface of clean Cu, Ag, and Au (i.e., the noble metals) in HV can significantly alter the energy-level alignment at metal/organic interfaces.

  11. Implications of noble gases in a recently recognized Martian meteorite (ALH84001) for the degassing history of Mars

    NASA Technical Reports Server (NTRS)

    Swindle, T. D.

    1994-01-01

    For terrestrial planets, atmospheric compositions are not static, but evolve with time, in part due to degassing of the interior. Unfortunately, the evolution is slow enough that it is usually not observable on human timescales, or even on the timescales of rocks that preserve samples of Earth's ancient atmosphere. Preliminary results on a recently recognized Martian meteorite, ALH84001, indicate that it is a very old rock, and has a relatively high noble gas content suggestive of atmospheric incorporation, but with an isotopic composition slightly inconsistent with currently known Martian reservoirs. Hence, this rock may provide a sample of ancient Martian atmosphere, which can be used to test models of volatile evolution (in particular, degassing) on Mars. ALH84001 is a cumulate orthopyroxenite. Although originally classified as a diogenite, its oxygen isotopes, and several chemical and petrographic features, strong suggest that it is, like the SNC meteorites, Martian. A Sm-Nd crystallization age of 4.5 Ga has been reported. The meteorite is rich in noble gases, compared to most SNC's. In many respects the noble gases are typical of SNC meteorites. However, there are some subtle differences. In particular, the Xe isotopes in SNC meteorites can be explained as a mixture of Martian atmospheric Xe (as represented by glass in EETA 79001), the Xe in the dunite Chassigny (usually assumed to be representative of the Martian interior, and with lower (129)Xe/(132)Xe, (134)Xe/(132)Xe and (136)Xe/(132)Xe ratios), and later additions from known processes like fission, spallation and terrestrial contamination. The isotopic composition of ALH84001 is inconsistent (at greater than 2-3 sigma) with any mixture of those components. Even if no accumulation of fission Xe during the age of the rock is assumed, there is too little (136)Xe and (134)Xe for the amount of (129)Xe measured.

  12. Noble Gases and CRE Ages of Eucrites NWA 5073, NWA 2550 and HaH 286

    NASA Astrophysics Data System (ADS)

    Cartwright, J. A.; Ott, U.; Roszjar, J.; Barrat, J. A.; Bischoff, A.

    2012-09-01

    We report the first noble gas and CRE age data for basaltic eucrites NWA 5073, NWA 2550 and HaH 286 in research to better understand the impact history on Vesta. Our preliminary results correlate with an ejection event at ~22 Ma and one at 65-70 Ma.

  13. Noble Gases in Two Meteorites that Fell in Denmark and Slovenia in 2009

    NASA Astrophysics Data System (ADS)

    Ott, U.; Herrmann, S.; Haack, H.; Grau, T.

    2010-03-01

    From noble gas analyes we obtain for CM2 Maribo and an as yet unapproved stone (ordinary chondrite) that fell in Slovenia in April 2009 CRE ages of ~1 and ~ 4 Ma. Ne and Xe isotopes in Maribo indicate the presence of presolar diamond and SiC.

  14. Noble Gases of the Jinju (H5) Meteorite Fell on March 9, 2014, in Korea

    NASA Astrophysics Data System (ADS)

    Nagao, K.; Haba, M. K.; Lee, J. I.; Kim, T.; Lee, M. J.

    2015-07-01

    Noble gas compositions of the Jinju meteorite that fell in Korea show relatively short cosmic-ray exposure age of (2-3) My, almost perfect retention of radiogenic 4He and 40Ar for about 40 Gy, and support the petrologic classification of H5.

  15. Noble Gases in the Light and Dark Phase of a Meteorite Found in Novato, California

    NASA Astrophysics Data System (ADS)

    Busemann, H.; Clay, P. L.; Jenniskens, P.; Meier, M. M. M.; Wieler, R.

    2013-09-01

    We present noble gas results on a solar wind free chondrite found with the help of a dedicated camera network near Novato, CA. The results are typical for L6 chondritic material that has experienced the parent body disruption 470 Ma ago.

  16. 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

  17. Evidence for multiple magma ocean outgassing and atmospheric loss episodes from mantle noble gases

    NASA Astrophysics Data System (ADS)

    Tucker, J.; Mukhopadhyay, S.

    2013-12-01

    Giant impacts are theorized to generate global magma oceans during Earth's accretion. However, geochemical evidence requiring a terrestrial magma ocean is scarce. We will present evidence that the 3He/22Ne ratio in the depleted mantle requires at least two separate episodes of giant impact-induced atmospheric blow-off and magma ocean outgassing on Earth. 3He/22Ne ratios in the mantle source of equatorial Atlantic mid-ocean ridge basalts correlate with Ne, Pb and Nd isotope ratios, establishing that mantle 3He/22Ne variability is caused by recent mixing of sources with different endmember compositions. Our data define the 3He/22Ne ratio of the depleted mantle to be ≥10, whereas primitive material sampled by plumes has a value of ~2.3-3. These terrestrial ratios are higher than all possible sources of volatile elements, in particular the solar nebula with a value of 1.5. Therefore a planetary process must have raised the mantle's 3He/22Ne ratio. We demonstrate that long-term plate tectonic cycling is incapable of fractionating He and Ne significantly in 4.5 Ga and if anything would lower their ratio. However, solubility-controlled ingassing or outgassing of a magma ocean is predicted to raise the 3He/22Ne ratio in the mantle during Earth's accretion. The 3He/22Ne ratio as well as the 20Ne/22Ne ratio of primitive material sampled by plumes is consistent with ingassing a gravitationally accreted nebular atmosphere into a magma ocean. Ingassing would raise the mantle 3He/22Ne over the nebular value by at most a factor of ~2, the He/Ne solubility ratio in a pyrolitic magma ocean. The 6.5× enhancement in the 3He/22Ne of the depleted mantle over the nebular value requires at least two additional episodes of giant impact-induced atmospheric blow-off and magma ocean outgassing, the last of which being the Moon-forming impact. Each of these outgassing episodes raises the mantle 3He/22Ne ratio by at most a factor of ~2. We note that atmospheric blow-off is necessary for driving He/Ne fractionation in the mantle. The large differences in the 3He/22Ne of the primitive reservoir and the depleted mantle require that the giant impacts, including the Moon-forming impact, could not have melted and homogenized the whole mantle. Hence, if primordial noble gases in plumes are derived from large low shear velocity provinces (LLSVPs) at the core-mantle boundary, these features did not form from crystallization of the magma ocean associated with the Moon-forming impact. LLSVPs may have formed from crystallization products of previous magma oceans and survived the Moon-forming impact, or else their formation is unrelated to magma oceans. Along with 20Ne/22Ne and 129Xe/130Xe, the disparate 3He/22Ne ratios between mantle domains require that 4.5 billion years of mantle convection has not erased chemical differences set up during accretion.

  18. 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).

  19. Noble gases in anhydrous lherzolites from the newer volcanics, southeastern Australia: a MORB-like reservoir in the subcontinental mantle *1

    NASA Astrophysics Data System (ADS)

    Matsumoto, Takuya; Honda, Masahiko; Mcdougall, Ian; O'Reilly, Suzanne Y.

    1998-07-01

    In order to understand the nature of noble gas reservoirs beneath continents, elemental and isotopic compositions of noble gases were analyzed from spinel-lherzolites with anhydrous mineral assemblages (i.e., olivine > clinopyroxene ˜ orthopyroxene > spinel); these are considered to be typical of the upper lithospheric mantle. The observed noble gas elemental and isotopic compositions are very similar to those found in MORBs. Characteristic features include (1) 3He/ 4He ratio of about 1 × 10 -5, (2) linearly correlated 20Ne/ 22Ne and 21Ne/ 22Ne ratios plotting on the well-established MORB-line, (3) relatively high 40Ar/ 36Ar ratios, and (4) correlated excesses in 129Xe and 136Xe with respect to atmospheric xenon. In addition, 3He to 22Ne ratios are close to those of a solar component, reinforcing the view that the Earth contains primordial helium and neon of solar composition. The MORB-like noble gases are trapped predominantly in CO 2-rich fluid inclusions, which are inferred to be of secondary origin. These gases probably are of metasomatic origin, having been introduced into the lithospheric mantle from the convective upper mantle by CO 2-bearing melts. The results indicate that a MORB-like noble gas reservoir may characterize the upper part of the mantle on a global scale. This reservoir may be underlain by a relatively less degassed mantle reservoir, as plume-like mantle noble gases also have been identified beneath southeastern Australia (Matsumoto et al., 1997). Thus, some form of chemical layering appears to be required to explain the noble gas signatures both in the subcontinental and suboceanic mantle.

  20. 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.

  1. 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.

  2. Laboratory shock emplacement of noble gases, nitrogen, and carbon dioxide into basalt, and implications for trapped gases in shergottite EETA 79001

    NASA Technical Reports Server (NTRS)

    Wiens, R. C.; Pepin, R. O.

    1988-01-01

    Basalts from the Servilleta flows, Taos, NM, described by Lofgren (1983) were analyzed by mass spectrometry for shock-implanted noble gases, N2, and CO2 (which were isotopically labeled) after an exposure to 20-60 GPa shock in the presence of 0.0045-3.0 atm of ambient gas. The results were compared with data available on the constituents of the EETA 79001 meteorite. As expected, the samples shocked in this study attained emplacement efficiencies significantly lower than those apparent for lithology C of EETA 79001. Possible explanations for this difference include atmospheric overpressure at the time of EETA 79001 exposure to shock, the trapping of gas already in vugs by the intruding melt material, or the collapse of gas-filled vugs to form gas-laden glass inclusions.

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

    SciTech Connect

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

    1993-02-01

    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 [sup 20]Ne and [sup 21]Ne by as much as 16% with respect to atmospheric ratios. All the Hawaiian basalt glass samples show relatively high [sup 3]He/[sup 4]He ratios. The high [sup 20]Ne/[sup 22]Ne 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 CO[sub 2] well gases, and in ancient diamonds. These results provide new insights into the origin and evolution of the Earth's atmosphere.

  4. The measurement of radioactive noble gases by DWD in the frame of the Global Atmospheric Watch programme of WMO.

    PubMed

    Steinkopff, T; Dyck, W; Frank, G; Frenzel, S; Salvamoser, J

    2004-01-01

    The Deutscher Wetterdienst (DWD, German Meteorological Service) is integrated into the Global Atmospheric Watch programme (GAW) of the World Meteorological Organization (WMO). According to this programme a variety of chemical compounds and radionuclides are measured at global stations. At the research platform "Schneefernerhaus" 7Be, 222Rn, and its decay products, 14C in CO2, tritium as HTO, 85Kr and 133Xe are continuously monitored by the DWD or are sampled and then measured at the central laboratory in Offenbach. The results are used as additional information for studying atmospheric mixing processes or on the other hand as information about the background level of radioactivity. As a main subject of this paper the integration and partly the optimization of sampling and measuring procedures for the detection of noble gases are described. In particular, the methods of quality assurance are discussed for Kr and Xe. PMID:15177349

  5. Examination of (e,2e) scattering models by comparison of momentum profiles of noble gases between experiment and theory.

    PubMed

    Miyake, Yusuke; Takahashi, Masahiko; Watanabe, Noboru; Khajuria, Yugal; Udagawa, Yasuo; Sakai, Yasuhiro; Mukoyama, Takeshi

    2006-07-01

    Momentum profiles have been measured for the two outermost atomic orbitals of noble gases, Ar, Kr and Xe, at incident electron energy of about 2 keV using a newly developed multichannel (e,2e) spectrometer. The experimental results exhibit significantly improved statistics compared with those achieved in previous studies while covering a wide range of momenta up to 3.6 a.u. The results are compared with theoretical calculations using four (e,2e) scattering models, the plane-wave impulse and Born approximations (PWIA and PWBA), and the distorted-wave impulse and Born approximations (DWIA and DWBA). The DWIA and DWBA scattering models have been found to satisfactorily reproduce the experimental momentum profiles in terms of both shape and intensity over the entire momentum range covered, indicating the importance of distorted wave effects for quantitatively describing (e,2e) reaction. PMID:16880916

  6. Spreading of Greenland meltwaters in the ocean revealed by noble gases

    NASA Astrophysics Data System (ADS)

    Beaird, Nicholas; Straneo, Fiammetta; Jenkins, William

    2015-09-01

    We present the first noble gas observations in a proglacial fjord in Greenland, providing an unprecedented view of surface and submarine melt pathways into the ocean. Using Optimum Multiparameter Analysis, noble gas concentrations remove large uncertainties inherent in previous studies of meltwater in Greenland fjords. We find glacially modified waters with submarine melt concentrations up to 0.66 ± 0.09% and runoff 3.9 ± 0.29%. Radiogenic enrichment of Helium enables identification of ice sheet near-bed melt (0.48 ± 0.08%). We identify distinct regions of meltwater export reflecting heterogeneous melt processes: a surface layer of both runoff and submarine melt and an intermediate layer composed primarily of submarine melt. Intermediate ocean waters carry the majority of heat to the fjords' glaciers, and warmer deep waters are isolated from the ice edge. The average entrainment ratio implies that ocean water masses are upwelled at a rate 30 times the combined glacial meltwater volume flux.

  7. Shock-implanted noble gases - An experimental study with implications for the origin of Martian gases in shergottite meteorites

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.; Horz, Friedrich; Johnson, Pratt H.

    1986-01-01

    The shock-implantation of gases is studied by artificially shocking whole rock and power samples of terrestrial basalt to pressures of 2-40 GPa. Ar, Kr, Xe, and Ne were implanted into the silicate. It is observed that the amount of implanted gas is linearly proportional to its partial pressure over a pressure range of 0.0001 to 0.1 atmosphere. The fractionation effect in the implanted gas and the gas diffusion properties are examined. The amounts of gas that would have been implanted with 100 percent efficiency are calculated from the measured porosities of the power samples and are compared to observed abundances. It is determined that the implantation efficiencies are approximately 0.5 percent at 2 GPa, 7 percent at 5 GPa, and greater than 50 percent at both 20 and 35 GPa. The experimental data correlate with the shock implantation of Martian gases without mass fractionation into the shock-melted phase of meteorite EETA 79001.

  8. 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.

  9. 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).

  10. Titan's Lakes Chemical Composition: Sources Of Uncertainties And Variability, Implications For Noble Gases Sequestration

    NASA Astrophysics Data System (ADS)

    Cordier, Daniel; Mousis, O.; Lunine, J.; Lebonnois, S.; Rannou, P.; Lavvas, P.; Lobo, L.; Ferreira, A.

    2010-10-01

    In 2007, the instruments of the CASSINI spacecraft, orbiting within the system of Saturn, allowed the discovery of RADAR dark-patches in the polar regions of the main kronian moon. These features are interpreted as hydrocarbon lakes with ethane identified as the main compound. In order to detail the composition of these lakes, numerical simulations have been recently performed assuming thermodynamic equilibrium between the atmosphere and the liquid phase. Here we first explore the influence of thermodynamic data uncertainties on the computed lakes chemical composition. To do so, we perform Monte-Carlo simulations in order to mimic the relevant uncertainties. In a second stage we examine the hypothesis that Titan's hydrocarbon lakes could be at the origin of the strong noble gas depletion measured in the atmosphere by the Huygens probe.

  11. Irradiation History of Itokawa Regolith Material Deduced from Noble Gases in the Hayabusa Samples

    NASA Astrophysics Data System (ADS)

    Nagao, Keisuke; Okazaki, Ryuji; Nakamura, Tomoki; Miura, Yayoi N.; Osawa, Takahito; Bajo, Ken-ichi; Matsuda, Shintaro; Ebihara, Mitsuru; Ireland, Trevor R.; Kitajima, Fumio; Naraoka, Hiroshi; Noguchi, Takaaki; Tsuchiyama, Akira; Yurimoto, Hisayoshi; Zolensky, Michael E.; Uesugi, Masayuki; Shirai, Kei; Abe, Masanao; Yada, Toru; Ishibashi, Yukihiro; Fujimura, Akio; Mukai, Toshifumi; Ueno, Munetaka; Okada, Tatsuaki; Yoshikawa, Makoto; Kawaguchi, Junichiro

    2011-08-01

    Noble gas isotopes were measured in three rocky grains from asteroid Itokawa to elucidate a history of irradiation from cosmic rays and solar wind on its surface. Large amounts of solar helium (He), neon (Ne), and argon (Ar) trapped in various depths in the grains were observed, which can be explained by multiple implantations of solar wind particles into the grains, combined with preferential He loss caused by frictional wear of space-weathered rims on the grains. Short residence time of less than 8 million years was implied for the grains by an estimate on cosmic-ray-produced 21Ne. Our results suggest that Itokawa is continuously losing its surface materials into space at a rate of tens of centimeters per million years. The lifetime of Itokawa should be much shorter than the age of our solar system.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  13. 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.

  14. 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 (δ2H, δ18O), δ13C 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.

  15. Cometary Nitrogen-Noble gases and the Origin of the Oceans: Waiting for ROSINA-Rosetta Data

    NASA Astrophysics Data System (ADS)

    Marty, B.; Calmonte, U.; Altwegg, K.; Balsiger, H. R.; Bar-Nun, A.; Berthelier, J. J.; Bieler, A. M.; Dhooghe, F.; Fiethe, B.; Mall, U. A.; Mousis, O.; Owen, T. C.; Rubin, M.

    2014-12-01

    The origin of the terrestrial oceans and atmosphere is still a matter of intensive debate. For a while high D/H ratios in comets compared to both meteorites and Earth's oceans (which share approximately the same range of values) has been taken as evidence for an asteroidal origin of the oceans. This possibility is in line with the N isotope composition of meteorites encompassing the terrestrial atmosphere value. Recently, Earth-like D/H ratios have been reported for two comets, thus re-vitalizing the possibility of cometary contribution to terrestrial volatiles. Nitrogen in cometary CN, HCN, and NH2 (the N-bearing molecules that can be analyzed remotely) is enriched by a factor of approx. 80% in 15N compared to terrestrial N. The question is whether or not these N-bearing molecules are representative of bulk N in comets. If nitrogen is trapped as N2 in cometary ices, its isotope composition could reflect that of the protosolar nebula, which was depleted by 40% relative to Earth. A cometary cocktail consisting of 1/3 reduced, 15N-rich N and 2/3 of nebula-like N2 would make the terrestrial N isotope composition. Another strong constraint will arise from the analysis of cometary noble gases which, if trapped at sufficiently low temperature in ice, could account for the elevated noble gas/H,C ratio of the terrestrial surface reservoirs. Hopefully, the ROSINA instrument on board of the Rosetta spacecraft which will analyze volatile elements degassed by comet 67/P Churyumov-Gerasimenko, which should permit to shed light on this fundamental issue.

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  17. Production Rates of Noble Gases in the Near-Surface Layers of Europa by Energetic Charged Particles and the Potential for Determining Exposure Ages

    NASA Technical Reports Server (NTRS)

    Swindle, T. D.; Reedy, R. C.; Masarik, J.

    2003-01-01

    The surface of Europa is expected to be extremely active, undergoing tectonic and/or tidal geological activity and sputtering/ deposition, as well as impact cratering. Determination of the actual age of the surface at one or more places would greatly simplify trying to sort out what processes are occurring, and at what rate. If there is K present, as the spectral and compositional modeling discussed predict, it should be possible, in principle, to determine K-Ar crystallization ages. Whether or not there is K present, a consideration of the environment suggests we can determine an energetic particle exposure age if we can make in situ measurements of the abundances of major elements and of noble gas isotopes. This requires instrumentation that is within reach of current technology. In this paper, we calculate production rates for noble-gas isotopes in a simplified Europan surface, to quantify the amount of light noble gases produced by exposure to energetic particles.

  18. Noble Gases and Siderophile Elements in the Mantle: Unconventional Experimental Results and Their Implications for Chemical Geodynamics

    NASA Astrophysics Data System (ADS)

    Watson, E. B.; Hayden, L. A.; Thomas, J. B.; Cherniak, D. J.

    2007-12-01

    Recent and ongoing experimental studies reveal unexpected behavior of noble gases and siderophile elements that may affect future geodynamic interpretations. Ar-uptake experiments on mantle minerals provide insight into Ar compatibility (solubility) and diffusivity in these phases. Contrary to expectation, solubility results suggest that Ar behaves as a compatible element during mantle melting, favoring residence in point defects in minerals over 'escape' to the melt. In terms of diffusion, Ar is sufficiently mobile in olivine and orthopyroxene to ensure effective dispersal from relatively K-rich minerals on a geodynamically short time scale. Solid-liquid equilibration during melting of the MORB source is also likely; however, Ar diffusion is slow enough for disequilibrium to arise during phenocryst growth in a pre-eruption setting. The main implications of these results are that: 1) Ar degassing of the mantle through MORB volcanism may be an inefficient process; and 2) the existence of deeply-sequestered Ar (and other noble gases?) is plausible. New data on the behavior of siderophile elements (Os, Ir, Ru, Rh, Pt, Re, Au, W, Mo, Co, Cu and C) in polycrystalline MgO and synthetic peridotite reveal that these elements are highly mobile in the grain boundaries of mantle assemblages and analogs. W, Au and C have the highest diffusivities (10-8 to 10-7 m2/s); Ir, Ru, Re and Os are at the low end of the range (~10-12 to 10-11 m2/s). There is no discernible correlation between grain-boundary diffusivity and any particular property of the atoms or elements. These new data imply that Earth's outer core may 'leak' siderophile elements into the lower mantle over distances exceeding 100 km in 4 GYr for W, Au and C. Although not significant in itself as a whole-mantle transport process, grain boundary diffusion appears capable of 'contaminating' the lower mantle over a sufficient distance to enable entrainment of a core signature into plume- or convective mantle flow. If the outer core contains C, our data suggest that there may be a significant core-to-mantle flux of this element.

  19. Transport of methane and noble gases during gas push-pull tests in dry porous media.

    PubMed

    Gonzalez-Gil, Graciela; Schroth, Martin H; Zeyer, Josef

    2007-05-01

    A field method called the gas push-pull test (GPPT) was previously developed and tested for the in situ quantification of aerobic methane (CH4) oxidation by soil microorganisms. The GPPT consists of an injection followed by extraction of reactant and tracer gases into and out of the soil. Quantification of microbial activities from GPPTs requires insight in the transport of reactant and tracer gases under diverse field conditions. We investigated how the transport of differenttracer gases (He, Ne, and Ar) compares to that of the reactant gas CH4 during GPPTs conducted in a well-defined, dry porous media that mimicked an open system. Transport of gaseous components during GPPT is mainly driven by advection resulting from injection and extraction and diffusion driven by concentration gradients. Regardless of the advective component (selected injection/ extraction, flow rates 0.2-0.8 L min(-1)), diffusion was the dominant transport mechanism for gaseous components. This resulted in dissimilar transport of CH4 and the tracers He and Ne. Numerical simulations of GPPTs showed that similar transport of these components is only achieved at very high injection/extraction rates that, in practice, are not feasible since they would imply extremely short duration times of GPPTs to allow for consumption of a measurable amount of reactant(s) by soil microorganisms. However, Ar transport was similar to that of CH4. Hence, Ar may be a good tracer provided that it is injected at high concentrations (e.g., >25% [v/v]) to overcome its background concentration in soil air. Using moderate injection/ extraction rates (e.g., 0.6 L min(-1)) with injected volumes of 10-30 L will result in GPPT durations of 1-3 h, which would suffice to attain a measurable consumption of reactant(s) in soils having relatively high (e.g., first-order rate constants >0.3 h(-1)) microbial activities. PMID:17539535

  20. Noble gases fingerprint a metasedimentary fluid source in the Macraes orogenic gold deposit, New Zealand

    NASA Astrophysics Data System (ADS)

    Goodwin, Nicholas R. J.; Burgess, Ray; Craw, Dave; Teagle, Damon A. H.; Ballentine, Chris J.

    2016-04-01

    The world-class Macraes orogenic gold deposit (˜10 Moz resource) formed during the late metamorphic uplift of a metasedimentary schist belt in southern New Zealand. Mineralising fluids, metals and metalloids were derived from within the metasedimentary host. Helium and argon extracted from fluid inclusions in sulphide mineral grains (three crush extractions from one sample) have crustal signatures, with no evidence for mantle input (R/Ra = 0.03). Xenon extracted from mineralised quartz samples provides evidence for extensive interaction between fluid and maturing organic material within the metasedimentary host rocks, with 132Xe/36Ar ratios up to 200 times greater than air. Similarly, I/Cl ratios for fluids extracted from mineralised quartz are similar to those of brines from marine sediments that have interacted with organic matter and are ten times higher than typical magmatic/mantle fluids. The Macraes mineralising fluids were compositionally variable, reflecting either mixing of two different crustal fluids in the metasedimentary pile or a single fluid type that has had varying degrees of interaction with the host metasediments. Evidence for additional input of meteoric water is equivocal, but minor meteoric incursion cannot be discounted. The Macraes deposit formed in a metasedimentary belt without associated coeval magmatism, and therefore represents a purely crustal metamorphogenic end member in a spectrum of orogenic hydrothermal processes that can include magmatic and/or mantle fluid input elsewhere in the world. There is no evidence for involvement of minor intercalated metabasic rocks in the Macraes mineralising system. Hydrothermal fluids that formed other, smaller, orogenic deposits in the same metamorphic belt have less pronounced noble gas and halogen evidence for crustal fluid-rock interaction than at Macraes, but these deposits also formed from broadly similar metamorphogenic processes.

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

    SciTech Connect

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

    2015-03-15

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

  2. Dating and tracing groundwater resources in central Québec with noble gases, 14C and water chemistry

    NASA Astrophysics Data System (ADS)

    Vautour, G.; Pinti, D. L.; Castro, M. C.; Barbecot, F.; Larocque, M.; Hall, C. M.

    2011-12-01

    Canada water supply is derived mainly from lakes and rivers while groundwater accounts for less than 30% of the demand. Climatic and anthropogenic stress is endangering this natural resource. This study is part of a Quebec-funded program to characterize groundwater resources from major basins to ensure adequate water quality and management. The Bécancour River catchment area, 200 km NE of Montréal, is studied for this purpose. The region extends from the Appalachian Mts. down to the St. Lawrence River. Water chemistry shows the occurrence of Ca,Na-HCO3, Ca-HCO3, Na-HCO3 and NaCl waters, mainly recharged in the Appalachians and flowing to the St. Lawrence River. Aquifers are also recharged locally through Quaternary sandy deposits throughout the plain. Main aquifers are found both in unconfined and confined Quaternary sands intercalated with clays, and also locally in fractured Ordovician carbonates. To identify groundwater flow paths and to estimate water residence times, a multi-isotopic study involving noble gases, 14C and U, Th isotopes was initiated. Noble gas preliminary results were obtained on two transects, one along the downward flow path and the second perpendicular to the first, along a deeper sinclinorium with NaCl waters (TDS =170-705 mg/L). The 3He/4He ratios versus 4He/20Ne clearly points to mixing between three water bodies. The first has been recharged very recently displaying a near-atmospheric ratio of 0.79 Ra (Ra=atmospheric 3He/4He ratio of 1.386 x 10-6) and a 4He/20Ne of 0.2 close to the Air Saturated Water value, i.e. the ratio of atmospheric He and Ne dissolved in groundwater. The second water body is slightly older and shows the occurrence of tritiogenic 3He (3Hetri) excesses up to 1.07x10-13 ccSTP/g. These waters are found along the transect parallel to the main flow path. Using a local tritium decay curve and measured 3Hetri, an age of 19-20 years is suggested. The third water body contains large amounts of radiogenic 4He produced by U and Th decay in aquifer rocks up to 4.48x10-5 ccSTP/g. These waters are found close to the Appalachian recharge and in the transversal sinclinorium. They are from relatively deep wells (50 m depth), likely tapping the Ordovician carbonate basement. A simple in situ U-Th-4He age model gives ages of 2.0 to 6.6 Ma, which might suggest either: (1) the occurrence of isolated pockets of old water in the fractured basement or (2) mixing with deeper fossil brines containing large amounts of radiogenic 4He occurring in the Bécancour area. 14C measurements, in progress, should be helpful in calibrating the He age model and to test whether a 4He source external to aquifers might exist. Preliminary calculated paleotemperatures using atmospheric noble gases suggest values varying between 0° to 7 °C. The higher temperature represents actual recharge conditions during spring. The lower temperatures might correspond to Holocene waters recharged during the last deglaciation or contribution from recent glacial meltwater.

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

    SciTech Connect

    Fahleson, Tobias; Norman, Patrick; Coriani, Sonia; Rizzo, Antonio; Rikken, Geert L. J. A.

    2013-11-21

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

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

    NASA Astrophysics Data System (ADS)

    Fahleson, Tobias; Norman, Patrick; Coriani, Sonia; Rizzo, Antonio; Rikken, Geert L. J. A.

    2013-11-01

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

  5. 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∗.

  6. Volatiles (nitrogen, noble gases) in recently discovered SNC meteorites, extinct radioactivities and evolution

    NASA Astrophysics Data System (ADS)

    Mathew, K. J.; Marty, B.; Marti, K.; Zimmermann, L.

    2003-09-01

    We report noble gas and nitrogen analyses of newly discovered SNC meteorites, one nakhlite (NWA817) and four shergottites (NWA480, NWA856, NWA1068, and SaU 005). The K-Ar age (1.3 Ga) as well as the cosmic-ray exposure (CRE) age (10.01.3 Ma) of nakhlite NWA817 agree with data of Nakhla. The CRE ages of NWA480, NWA856, and NWA1068 (2.350.20, 2.600.21 and 2.010.65 Ma, respectively) are consistent, within uncertainties, with other basaltic shergottites, but the CRE age of SaU 005 (1.250.07 Ma) is distinct and indicates a different ejection event. Bulk K-Ar ages of all shergottites exceed the reported radiometric ages and reveal the presence of inherited radiogenic 40Ar in basaltic lavas. The isotopic composition of nitrogen trapped in these SNC meteorites is not homogeneous, since ? 15N values of either +15 to 20 or +45, indicate different nitrogen reservoirs. All shergottites contain fission xenon from 238U, and fission Xe of extinct ( T1/2=82 Ma) 244Pu, previously identified in ALH84001, in Chassigny and in Nakhla is also present in at least one shergottite (NWA856). The shergottites contain less fissiogenic Xe than other SNC, suggesting that either their source was more degassed or that the magma source region closed at a later time. In nakhlites, fission xenon from 244Pu correlates with uranium, a geochemical proxy of plutonium. Thus it is possible that fissiogenic Xe was not inherited during magma differentiation, but rather was produced in situ and retained in refractory mineral assemblages. In this interpretation, the magma evolution that settled the mineralogy and geochemistry of nakhlites took place at a time when 244Pu was alive and pre-dated the (late) events recorded in their radiometric ages. Alternatively, fissiogenic xenon was trapped from a mantle source during closed system evolution of the parent magmas, in which case such evolution might have taken place at considerable depth (pressure) in order to inhibit magma degassing during the course of differentiation.

  7. Th and U Recycling Through Subduction; Noble Gases and Pb Isotope Evidence

    NASA Astrophysics Data System (ADS)

    Hanyu, T.; Kawabata, H.; Kimura, J. I.; Tatsumi, Y.

    2014-12-01

    HIMU is one of mantle components that has been recognized to form by subduction and subsequent storage of ancient oceanic crust in the mantle. We use noble gas and Pb isotopic compositions of HIMU basalts to constrain age of reservoir formation and recycling of K, U, and Th. It has been confirmed that subaerial and submarine Austral Islands HIMU basalts show low 3He/4He relative to MORB, indicating the HIMU reservoir involving either U-enriched or He-depleted material. Moreover, fractionation-corrected 4He/40Ar* of the HIMU basalts is higher than the 4He/40Ar* production ratio in the mantle. This suggests that K/U of the HIMU component converted from 4He/40Ar* is approximately 3000, and hence lower than the canonical mantle K/U of 13000. These facts are best explained by a model that the HIMU component originates from subducted oceanic crust that preferentially lost He and K relative to U and Th during subduction. The St. Helena HIMU basalts in the Atlantic show systematically higher 207Pb/204Pb for a given 206Pb/204Pb than the Austral Islands HIMU basalts in the Pacific. The Pb isotope evolution model suggests that both HIMU components formed around 2 Ga; however, the HIMU component beneath Atlantic is about 0.3 Ga older than that beneath Pacific. We interpret the age difference as that the HIMU reservoir for St. Helena involved old subducted materials more abundant than that for Austral Islands during the long-term accumulation of subducted materials. Using the same Pb evolution model, Th/U deduced from the 206Pb/204Pb-208Pb/204Pb relationship (3.3-3.7) is higher than that of present-day altered MORB (<2), Th/U of which is lowered by addition of U from oxic hydrothermal fluids. This suggests that either the HIMU precursor was fresh MORB, or more likely, hydrothermally altered MORB with minimal U enrichment in the less oxic environment in the Archean or early Proterozoic.

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

    SciTech Connect

    Lee, Hyo-Chang; Hwang, Hye-Ju; Kim, Young-Cheol; Kim, June Young; Kim, Dong-Hwan; Chung, Chin-Wook

    2013-03-15

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

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

    NASA Astrophysics Data System (ADS)

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

    1991-11-01

    Isotopic composition of solar-flare (SF) Ne was determined in acid-etched pyroxene mineral separates from the Kapoeta meteorite, a brecciated meteorite known to contain implanted solar gases. The results yield the SF Ne-20/Ne-22 ratio of 11.6 +/-0.2, confirming previous determinations of this SF ratio in lunar and meteoritic samples. The same SF Ne composition was also obtained by applying an ordinate intercept technique to the same data set. The ordinate intercept technique was then applied to the Ar and He data. The results are SF Ar-36/Ar-38 = 4.9 +/-0.1 and SF He-4/He-3 = 3800 +/-200. These values are significantly different from the solar-wind (SW) Ar and He values. It is estimated that the concentration of the SF component in Kapoeta pyroxenes is about 20 percent that of the SW component, orders of magnitude higher than expected from SW and SF proton flux measurements.

  10. Halogens and noble gases in Mathematician Ridge meta-gabbros, NE Pacific: implications for oceanic hydrothermal root zones and global volatile cycles

    NASA Astrophysics Data System (ADS)

    Kendrick, Mark A.; Honda, Masahiko; Vanko, David A.

    2015-12-01

    Six variably amphibolitised meta-gabbros cut by quartz-epidote veins containing high-salinity brine, and vapour fluid inclusions were investigated for halogen (Cl, Br, I) and noble gas (He, Ne, Ar, Kr, Xe) concentrations. The primary aims were to investigate fluid sources and interactions in hydrothermal root zones and determine the concentrations and behaviours of these elements in altered oceanic crust, which is poorly known, but has important implications for global volatile (re)cycling. Amphiboles in each sample have average concentrations of 0.1-0.5 wt% Cl, 0.5-3 ppm Br and 5-68 ppb I. Amphibole has Br/Cl of ~0.0004 that is about ten times lower than coexisting fluid inclusions and seawater, and I/Cl of 2-44 × 10-6 that is 3-5 times lower than coexisting fluid inclusions but higher than seawater. The amphibole and fluid compositions are attributed to mixing halogens introduced by seawater with a large halogen component remobilised from mafic lithologies in the crust and fractionation of halogens between fluids and metamorphic amphibole formed at low water-rock ratios. The metamorphic amphibole and hydrothermal quartz are dominated by seawater-derived atmospheric Ne, Ar, Kr and Xe and mantle-derived He, with 3He/4He of ~9 R/Ra (Ra = atmospheric ratio). The amphibole and quartz preserve high 4He concentrations that are similar to MORB glasses and have noble gas abundance ratios with high 4He/36Ar and 22Ne/36Ar that are greater than seawater and air. These characteristics result from the high solubility of light noble gases in amphibole and suggest that all the noble gases can behave similarly to `excess 40Ar' in metamorphic hydrothermal root zones. All noble gases are therefore trapped in hydrous minerals to some extent and can be inefficiently lost during metamorphism implying that even the lightest noble gases (He and Ne) can potentially be subducted into the Earth's mantle.

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

    PubMed

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

    1991-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    Environmental isotopes and noble gases in groundwater samples from the Kazan Trona Ore Field are studied to establish the temperature change between the Holocene and the late Pleistocene. Noble gas temperatures (NGTs) presented in this study add an important facet to the global paleotemperature map in the region between Europe and North Africa. The groundwater system under investigation consists of three different aquifers named shallow, middle and deep in which δ18O and δ2H vary from - 8.10‰ to - 12.80‰ and from - 60.89‰ to - 92.60‰ VSMOW, respectively. The average isotopic depletion between unconfined and confined parts of the system is - 2.5‰ in δ18O and - 20‰ in δ2H. It is not possible to explain this depletion solely with the elevation effect. Recharge temperatures derived from dissolved atmospheric noble gases reflect the current average yearly ground temperatures (13°C) for samples collected near the recharge area but are 3 to 8°C lower than today's temperatures in the deep aquifer system. Low 14C activities and high He excesses in the confined parts of the aquifer system suggest that the water in the deep aquifer was recharged during the last Pleistocene under considerably cooler climatic conditions.

  13. Estimation of self-absorption effect on aluminum emission in the presence of different noble gases: comparison between thin and thick plasma emission.

    PubMed

    Rezaei, F; Karimi, P; Tavassoli, S H

    2013-07-20

    Aluminum spectra in the noble gases of helium and argon at initial delay times after plasma formation are numerically calculated. Temporal behavior of plasma emissions up to 200 ns after laser irradiation is investigated. Plasma parameters are computed by coupling the thermal model of laser ablation, hydrodynamic of plasma expansion, and Saha-Eggert equations. A spectrum is constructed from the superposition of 13 strong lines of aluminum and several strong lines of ambient gases. Spectral radiations are superimposed on a continuous emission composed of bremsstrahlung and recombination radiation. The self-absorption effect on plasma radiation at 1 atm gas pressure is studied. In this paper, a comparison between thin and thick aluminum radiation is done. Furthermore, the self-absorption coefficient of each strong line at laser energies of 0.5, 0.7, 0.9, and 1.1 GW/cm(2) is estimated. Results show that at specific laser energy, the self-absorption effect in argon is more significant than in helium. For most of the spectral lines in both noble gases, the self-absorption coefficient will diminish with the delay time. As indicated with passing time, the line widths of the self-absorbed lines will rise. More intense continuous emissions are observed at higher wavelengths, and these radiations will be increased with laser energy. PMID:23872753

  14. Absolute cross sections for electron loss, electron capture, and multiple ionization in collisions of C{sup 3+} with noble gases

    SciTech Connect

    Santos, A. C. F.; Sant'Anna, M. M.; Montenegro, E. C.; Sigaud, G. M.; Melo, W. S.

    2010-07-15

    Absolute charge-state-correlated cross sections for projectile electron loss, electron capture, and target multiple ionization in collisions between C{sup 3+} ions and noble gases have been measured for energies between 1.3 and 3.5 MeV. The data have been compared with other similar absolute cross sections existent in the literature for several projectiles. Calculations for the single-loss-multiple-ionization channel have been performed for the screening mode, using both an extended version of the classical-impulse free-collision model and the plane-wave Born approximation (PWBA), and for the antiscreening mode within the PWBA. The energy dependence of the average number of target active electrons which contribute to the antiscreening has been described by means of a simple function, which is ''universal'' for noble gases but, in principle, projectile dependent. A method has been developed to obtain the number of active target electrons for each subshell in the high-velocity regime, which presented physically reasonable results. Analyses of the dependences of the single-capture and transfer-ionization (SC and TI, respectively) processes on the projectile charge states showed that, for He, equally charged bare and dressed projectiles have very similar cross sections; the latter thus acting as structureless point charges. A behavior similar to that in the SC has been observed for the pure single ionization of He by projectiles with different charge states and of the other noble gases by singly charged projectiles. It has been shown that the q{sup 2} dependence of the pure-single and total-ionization cross sections, predicted by first-order models, is only valid for high-collision velocities. For slower collisions, the electron capture process becomes more relevant and competes with the ionization channel, a feature which grows in importance as the projectile charge state increases.

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

    SciTech Connect

    Ottonello, Giulio; Richet, Pascal

    2014-01-28

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

  16. The L3-6 chondritic regolith breccia Northwest Africa (NWA) 869: (II) Noble gases and cosmogenic radionuclides

    NASA Astrophysics Data System (ADS)

    Welten, Kees; Caffee, Marc W.; Franke, Luitgard; Timothy Jull, A. J.; Leclerc, Marlene D.; Metzler, Knut; Ott, Ulrich

    2011-07-01

    We measured cosmogenic radionuclides and noble gases in the L3-6 chondrite breccia Northwest Africa (NWA) 869, one of the largest meteorite finds from the Sahara. Concentrations of 10Be, 26Al, and 36Cl in stone and metal fractions of six fragments of NWA 869 indicate a preatmospheric radius of 2.0-2.5 m. The 14C and 10Be concentrations in three fragments yield a terrestrial age of 4.4 ± 0.7 kyr, whereas two fragments show evidence for a recent change in shielding, most likely due to a recent impact on the NWA meteoroid, approximately 105 yr ago, that excavated material up to approximately 80 cm deep and exposed previously shielded material to higher cosmic-ray fluxes. This scenario is supported by the low cosmogenic 3He/21Ne ratios in these two samples, indicating recent loss of cosmogenic 3He. Most NWA samples, except for clasts of petrologic type 4-6, contain significant amounts of solar Ne and Ar, but are virtually free of solar helium, judging from the trapped 4He/20Ne ratio of approximately 7. Trapped planetary-type Kr and Xe are most clearly present in the bulk and matrix samples, where abundances of 129Xe from decay of now extinct 129I are highest. Cosmogenic 21Ne varies between 0.55 and 1.92 × 10-8 cm3 STP g-1, with no apparent relationship between cosmogenic and solar Ne contents. Low cosmogenic (22Ne/21Ne)c ratios in solar gas free specimens are consistent with irradiation in a large body. Combined 10Be and 21Ne concentrations indicate that NWA 869 had a 4π cosmic-ray exposure (CRE) age of 5 ± 1 Myr, whereas elevated 21Ne concentrations in several clasts and bulk samples indicate a previous CRE of 10-30 Myr on the parent body, most probably as individual components in a regolith. Unlike many other large chondrites, NWA 869 does not show clear evidence of CRE as a large boulder near the surface of its parent body. Radiogenic 4He concentrations in most NWA 869 samples indicate a major outgassing event approximately 2.8 Gyr ago that may have also resulted in loss of solar helium.

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

    PubMed

    Ottonello, Giulio; Richet, Pascal

    2014-01-28

    The existing solubility data on noble gases in high-temperature silicate melts have been analyzed in terms of Scaling Particle Theory coupled with an ab initio assessment of the electronic, dispersive, and repulsive energy terms based on the Polarized Continuum Model (PCM). After a preliminary analysis of the role of the contracted Gaussian basis sets and theory level in reproducing appropriate static dipole polarizabilities in a vacuum, we have shown that the procedure returns Henry's law constants consistent with the values experimentally observed in water and benzene at T = 25 °C and P = 1 bar for the first four elements of the series. The static dielectric constant (ɛ) of the investigated silicate melts and its optical counterpart (ɛ(∞)) 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 σs, along the guidelines already used in the past for simple media such as water or benzene. The σs 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. PMID:25669554

  18. 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.

  19. Noble gases, their carrier phases, and argon chronology of upper mantle rocks from Zabargad Island, Red Sea

    NASA Astrophysics Data System (ADS)

    Trieloff, M.; Weber, H. W.; Kurat, G.; Jessberger, E. K.; Janicke, J.

    1997-12-01

    Three ultramafic bodies on Zabargad Island contain fresh peridotites with mostly unfractionated primitive bulk major and trace element abundances and mostly monomineralic vein rocks (pyroxenites, olivinites, homblendites, etc.). We analyzed a set of coarse grained vein rocks with the 40Ar- 39Ar technique applying high resolution stepheating. Neutron induced argon isotopes derived from Ca, K, and Cl, and the specific degassing behaviour of major and accessory minerals enabled us to separate and identify different trapped and radiogenic argon components and their hosts. Within two clinopyroxenites trapped argon is present in (1) low temperature, low 40Ar/36Ar phases (serpentine and/or fluid inclusions), (2) pyroxene-related Cl-rich carriers (pyroxene and/or associated microinclusions) and (3) amphiboles which are intimately and nonseparably intergrown with pyroxene. The amphiboles, which can texturally, chemically, and isotopically be divided into different generations, formed by interaction of spinels and pyroxenes with mantle fluids during different stages of diapiric uplift (Agrinier et al., 1993). Formation of these amphiboles and microinclusions in pyroxenes, along with incorporation of isotopically distinct Ar with 40Ar/36Ar ratios up to 8000, can be related to recent mantle metasomatism also evident in Arabian xenoliths (Henjes-Kunst et al., 1990) and must have been induced by a variety of mantle fluids. For a homblendite, in situ radiogenic and excess argon components could be separated: the plateau age of 18.7 1.3 Ma is in perfect agreement with a zircon Pb/Pb age of 18.4 1.0 Ma (Oberli et al., 1987) interpreted as the age of crustal intrusion. Obviously, the formation of the hornblendite occurred during the final stage of uplift, most probably by interaction with seawater, as suggested by strontium, oxygen, and hydrogen isotopic data (Agrinier et al., 1993) and the low 40Ar/36Ar ratio (305) of the trapped argon. 4He, 20Ne, 40Ar, and 36Ar were measured in the orthopyroxenite vein rock Z31 by stepwise crushing and subsequent total fusion. Isotopic ratios show a well defined correlation with crushing step that indicates the presence of two different types or generations of inclusions, which were subjected to different degrees of contamination by atmosphere type noble gases. As inclusions were trapped before tje main deformation of the peridotite complex (Kurat et al., 1993), argon with relatively low 40Ar/36Ar ratios ( ? 1500) was trapped in the mantle, which requires an admixture of argon of atmospheric composition to the source region of the peridotites. Radiogenic isotopes ( 4He, 40Ar) are dominated by the mantle source, however, the 4He/40Ar ratio (0.16) is much lower than expected from long term decay of radioactive parent nuclides U, Th, and K. Such low ratios, which have previously been observed also in mantle xenoliths, obviously reflect the indigenous peridotitic source and are most probably due to fractionation processes in the mantle.

  20. Working gases in thermoacoustic engines.

    PubMed

    Belcher, J R; Slaton, W V; Raspet, R; Bass, H E; Lightfoot, J

    1999-05-01

    The best working gases for thermoacoustic refrigeration have high ratios of specific heats and low Prandtl numbers. These properties can be optimized by the use of a mixture of light and heavy noble gases. In this paper it is shown that light noble gas-heavy polyatomic gas mixtures can result in useful working gases. In addition, it is demonstrated that the onset temperature of a heat driven prime mover can be minimized with a gas with large Prandtl number and small ratio of specific heats. The gas properties must be optimized for the particular application of thermoacoustics; it cannot be assumed that high specific heat ratio and low Prandtl number are always desirable. PMID:10335618

  1. Mean annual temperature in New Zealand during the last glacial maximum derived from dissolved noble gases in groundwater

    NASA Astrophysics Data System (ADS)

    Seltzer, A. M.; Stute, M.; Morgenstern, U.; Stewart, M. K.; Schaefer, J. M.

    2015-12-01

    This study presents a reconstruction of mean annual surface temperature in New Zealand over the last glacial period using groundwater noble gas paleothermometry. Low resolution 14C-derived mean recharge ages of groundwater from the Deep Moutere, Deep Wairau, and Taranaki aquifers range from roughly 41,500 yr to present, including the last glacial maximum (LGM). Modeled noble gas temperatures of probable glacial-age samples range from roughly 3.7-6.2 °C cooler than present. We present an error-weighted mean cooling of 4.6 ± 0.5°C relative to present during last glacial period. The screened depth intervals of some wells sampled in this study allow for a degree of mixing during extraction between groundwater layers of different recharge age. Mixing with modern groundwater may slightly elevate the noble gas temperatures (NGTs) of glacial-age samples while making them appear substantially younger. Given the uncertainty in dating, we cannot rule out a larger LGM temperature depression of up to ∼6 °C. The ∼4.6 °C cooling estimate agrees with a number of terrestrial paleoclimate reconstructions near the study area as well as the majority of nearby paleoceanographic temperature studies.

  2. Anionic chemistry of noble gases: formation of Mg-NG (NG = Xe, Kr, Ar) compounds under pressure.

    PubMed

    Miao, Mao-Sheng; Wang, Xiao-Li; Brgoch, Jakoah; Spera, Frank; Jackson, Matthew G; Kresse, Georg; Lin, Hai-Qing

    2015-11-11

    While often considered to be chemically inert, the reactivity of noble gas elements at elevated pressures is an important aspect of fundamental chemistry. The discovery of Xe oxidation transformed the doctrinal boundary of chemistry by showing that a complete electron shell is not inert to reaction. However, the reductive propensity, i.e., gaining electrons and forming anions, has not been proposed or examined for noble gas elements. In this work, we demonstrate, using first-principles electronic structure calculations coupled to an efficient structure prediction method, that Xe, Kr, and Ar can form thermodynamically stable compounds with Mg at high pressure (≥125, ≥250, and ≥250 GPa, respectively). The resulting compounds are metallic and the noble gas atoms are negatively charged, suggesting that chemical species with a completely filled shell can gain electrons, filling their outermost shell(s). Moreover, this work indicates that Mg2NG (NG = Xe, Kr, Ar) are high-pressure electrides with some of the electrons localized at interstitial sites enclosed by the surrounding atoms. Previous predictions showed that such electrides only form in Mg and its compounds at very high pressures (>500 GPa). These calculations also demonstrate strong chemical interactions between the Xe 5d orbitals and the quantized interstitial quasiatom (ISQ) orbitals, including the strong chemical bonding and electron transfer, revealing the chemical nature of the ISQ. PMID:26488848

  3. A 30,000 yr Continental Paleotemperature Record Derived from Noble Gases Dissolved in Groundwater from the San Juan Basin, New Mexico

    NASA Astrophysics Data System (ADS)

    Stute, Martin; Clark, Jordan F.; Schlosser, Peter; Broecker, Wallace S.; Bonani, Georges

    1995-03-01

    Paleotemperatures for the last glacial maximum (LGM) have been derived from noble gases dissolved in 14C-dated groundwater of the Ojo Alamo and the Nacimiento formations in the San Juan Basin, northwestern New Mexico. The difference in mean annual (ground) temperature between the Holocene and the LGM was determined to be 5.5 ± 0.7°C. A practically identical result, 5.2 ± 0.7°C, has been obtained previously from the Carrizo aquifer in southern Texas. This suggests that the southwestern United States was uniformly cooler during the LGM and that the mean annual temperature gradient along a transect from the Gulf of Mexico to northwestern New Mexico has been unchanged since the LGM. The noble gas paleotemperatures are supported by paleoecological evidence in the region. The Holocene/LGM temperature difference of 5.4°C indicates that a simple lapse rate calculation may be applied to convert the 1000-m glacial depression of snowlines in the Colorado Front Range into a temperature decrease. A continental temperature change of 5.4 ± 0.7°C is inconsistent with a temperature change of about 2°C determined for the surface waters of the Gulf of Mexico.

  4. Gas transport below artificial recharge ponds: insights from dissolved noble gases and a dual gas (SF6 and 3He) tracer experiment.

    PubMed

    Clark, Jordan F; Hudson, G Bryant; Avisar, Dror

    2005-06-01

    A dual gas tracer experiment using sulfur hexafluoride (SF6) and an isotope of helium (3He) and measurements of dissolved noble gases was performed at the El Rio spreading grounds to examine gas transport and trapped air below an artificial recharge pond with a very high recharge rate (approximately 4 m day(-1)). Noble gas concentrations in the groundwater were greater than in surface water due to excess air formation showing that trapped air exists below the pond. Breakthrough curves of SF6 and 3He at two nearby production wells were very similar and suggest that nonequilibrium gas transfer was occurring between the percolating water and the trapped air. At one well screened between 50 and 90 m below ground, both tracers were detected after 5 days and reached a maximum at approximately 24 days. Despite the potential dilution caused by mixing within the production well, the maximum concentration was approximately 25% of the mean pond concentration. More than 50% of the SF6 recharged was recovered by the production wells during the 18 month long experiment. Our results demonstrate that at artificial recharge sites with high infiltration rates and moderately deep water tables, transport times between recharge locations and wells determined with gas tracer experiments are reliable. PMID:15984768

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  6. 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

  7. 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 δ-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 13δCH4 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.

  8. 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.

  9. 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 δ13C and δD 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

  10. Influence of radiation damage on the thermal properties of silicon carbide implanted with heavy noble gas ions

    NASA Astrophysics Data System (ADS)

    Friedland, E.; van der Berg, N. G.

    2016-03-01

    Diffusion of heavy noble gas atoms in irradiation damaged single crystalline silicon carbide and the thermal etching of it is investigated at temperatures of 1300 °C and 1400 °C. For this purpose 360 keV krypton and xenon ions were implanted in commercial 6H-SiC wafers at 600 °C, which is far above the critical amorphization temperature of the target material. Width broadening of the implantation profiles and the retention of krypton and xenon during isothermal annealing was determined by RBS-analysis, whilst damage profiles were simultaneously obtained by α-particle channelling. No diffusion and no loss of the implanted species is detected in the implanted samples after isothermal annealing for 40 h at 1400 °C. However, thermal etching of the target material is observed at both annealing temperatures and leads at 1400 °C to a significant shift of the implantation profile towards the surface due to sublimation. RBS analysis shows that this occurs mainly during the initial stage of isothermal annealing, while surface loss during prolonged annealing is minimal. The resulting topographical modification of the surface during annealing was studied by scanning electron and atomic force microscopy. It indicates that the observed phenomenon is due to a relatively strong dependence of thermal etching on the defect density in the surface region, while the evolving surface roughness seems not to play a decisive role.

  11. Intriguing structures and magic sizes of heavy noble metal nanoclusters around size 55 governed by relativistic effect and covalent bonding

    NASA Astrophysics Data System (ADS)

    Zhao, X. J.; Xue, X. L.; Guo, Z. X.; Jia, Yu; Li, S. F.; Zhang, Zhenyu; Gao, Y. F.

    2015-11-01

    Nanoclusters usually display exotic physical and chemical properties due to their intriguing geometric structures in contrast to their bulk counterparts. By means of first-principles calculations within density functional theory, we find that heavy noble metal PtN nanoclusters around the size N = 55 begin to prefer an open configuration, rather than previously reported close-packed icosahedron or core-shell structures. Particularly, for PtN, the widely supposed icosahedronal magic cluster is changed to a three-atomic-layered structure with D6h symmetry, which can be well addressed by our recently established generalized Wulff construction principle (GWCP). However, the magic number of PtN clusters around 55 is shifted to a new odd number of 57. The high symmetric three-layered Pt57 motif is mainly stabilized by the enhanced covalent bonding contributed by both spin-orbital coupling effect and the open d orbital (5d96s1) of Pt, which result in a delicate balance between the enhanced Pt-Pt covalent bonding of the interlayers and negligible d dangling bonds on the cluster edges. These findings about PtN clusters are also applicable to IrN clusters, but qualitatively different from their earlier neighboring element Os and their later neighboring element Au. The magic numbers for Os and Au are even, being 56 and 58, respectively. The findings of the new odd magic number 57 are the important supplementary of the recently established GWCP.

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

    PubMed

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

    2014-09-18

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

  13. On the Size and Structure of Helium Snowballs Formed around Charged Atoms and Clusters of Noble Gases

    PubMed Central

    2013-01-01

    Helium nanodroplets doped with argon, krypton, or xenon are ionized by electrons and analyzed in a mass spectrometer. HenNgx+ ions containing up to seven noble gas (Ng) atoms and dozens of helium atoms are identified; the high resolution of the mass spectrometer combined with advanced data analysis make it possible to unscramble contributions from isotopologues that have the same nominal mass but different numbers of helium or Ng atoms, such as the magic He2084Kr2+ and the isobaric, nonmagic He4184Kr+. Anomalies in these ion abundances reveal particularly stable ions; several intriguing patterns emerge. Perhaps most astounding are the results for HenAr+, which show evidence for three distinct, solid-like solvation shells containing 12, 20, and 12 helium atoms. This observation runs counter to the common notion that only the first solvation shell is solid-like but agrees with calculations by Galli et al. for HenNa+ [J. Phys. Chem. A2011, 115, 730021568337] that reveal three shells of icosahedral symmetry. HenArx+ (2 ≤ x ≤ 7) ions appear to be especially stable if they contain a total of n + x = 19 atoms. A sequence of anomalies in the abundance distribution of HenKrx+ suggests that rings of six helium atoms are inserted into the solvation shell each time a krypton atom is added to the ionic core, from Kr+ to Kr3+. Previously reported strong anomalies at He12Kr2+ and He12Kr3+ [KimJ. H.; et al. J. Chem. Phys.2006, 124, 21430116774401] are attributed to a contamination. Only minor local anomalies appear in the distributions of HenXex+ (x ≤ 3). The distributions of HenKr+ and HenXe+ show strikingly similar, broad features that are absent from the distribution of HenAr+; differences are tentatively ascribed to the very different fragmentation dynamics of these ions. PMID:24128371

  14. 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.

  15. The evolution of Devonian hydrocarbon gases in shallow aquifers of the northern Appalachian Basin: Insights from integrating noble gas and hydrocarbon geochemistry

    NASA Astrophysics Data System (ADS)

    Darrah, Thomas H.; Jackson, Robert B.; Vengosh, Avner; Warner, Nathaniel R.; Whyte, Colin J.; Walsh, Talor B.; Kondash, Andrew J.; Poreda, Robert J.

    2015-12-01

    The last decade has seen a dramatic increase in domestic energy production from unconventional reservoirs. This energy boom has generated marked economic benefits, but simultaneously evoked significant concerns regarding the potential for drinking-water contamination in shallow aquifers. Presently, efforts to evaluate the environmental impacts of shale gas development in the northern Appalachian Basin (NAB), located in the northeastern US, are limited by: (1) a lack of comprehensive "pre-drill" data for groundwater composition (water and gas); (2) uncertainty in the hydrogeological factors that control the occurrence of naturally present CH4 and brines in shallow Upper Devonian (UD) aquifers; and (3) limited geochemical techniques to quantify the sources and migration of crustal fluids (specifically methane) at various time scales. To address these questions, we analyzed the noble gas, dissolved ion, and hydrocarbon gas geochemistry of 72 drinking-water wells and one natural methane seep all located ≫1 km from shale gas drill sites in the NAB. In the present study, we consciously avoided groundwater wells from areas near active or recent drilling to ensure shale gas development would not bias the results. We also intentionally targeted areas with naturally occurring CH4 to characterize the geochemical signature and geological context of gas-phase hydrocarbons in shallow aquifers of the NAB. Our data display a positive relationship between elevated [CH4], [C2H6], [Cl], and [Ba] that co-occur with high [4He]. Although four groundwater samples show mantle contributions ranging from 1.2% to 11.6%, the majority of samples have [He] ranging from solubility levels (∼45 × 10-6 cm3 STP/L) with below-detectable [CH4] and minor amounts of tritiogenic 3He in low [Cl] and [Ba] waters, up to high [4He] = 0.4 cm3 STP/L with a purely crustal helium isotopic end-member (3He/4He = ∼0.02 times the atmospheric ratio (R/Ra)) in samples with CH4 near saturation for shallow groundwater (P(CH4) = ∼1 atmosphere) and elevated [Cl] and [Ba]. These data suggest that 4He is dominated by an exogenous (i.e., migrated) crustal source for these hydrocarbon gas- and salt-rich fluids. In combination with published inorganic geochemistry (e.g., 87Sr/86Sr, Sr/Ba, Br-/Cl-), new noble gas and hydrocarbon isotopic data (e.g., 20Ne/36Ar, C2+/C1, δ13C-CH4) suggest that a hydrocarbon-rich brine likely migrated from the Marcellus Formation (via primary hydrocarbon migration) as a dual-phase fluid (gas + liquid) and was fractionated by solubility partitioning during fluid migration and emplacement into conventional UD traps (via secondary hydrocarbon migration). Based on the highly fractionated 4He/CH4 data relative to Marcellus and UD production gases, we propose an additional phase of hydrocarbon gas migration where natural gas previously emplaced in UD hydrocarbon traps actively diffuses out into and equilibrates with modern shallow groundwater (via tertiary hydrocarbon migration) following uplift, denudation, and neotectonic fracturing. These data suggest that by integrating noble gas geochemistry with hydrocarbon and dissolved ion chemistry, one can better determine the source and migration processes of natural gas in the Earth's crust, which are two critical factors for understanding the presence of hydrocarbon gases in shallow aquifers.

  16. Noble gases in oxidized residue prepared from the Saratov L4 chondrite and Raman spectroscopic study of residues to characterize phase Q

    NASA Astrophysics Data System (ADS)

    Matsuda, Jun-Ichi; Morishita, Kazuhiko; Nara, Masayuki; Amari, Sachiko

    2016-01-01

    We analyzed noble gases in an oxidized residue prepared from a HF-HCl residue of the Saratov L4 chondrite. The Ar, Kr, and Xe concentrations in the oxidized residue are two orders of magnitude lower than those in the HF-HCl residue, and they are close to concentrations in the bulk. The He and Ne concentrations are similar in the three samples. The Ne isotopic ratios are almost purely cosmogenic, indicating absence of presolar diamonds (the carrier of the HL component). Thus, Saratov contains phase Q without presolar diamond. A study of the Raman spectroscopic parameters for the HF-HCl residue and the oxidized residue shows large changes due to oxidation. The directions of these changes are the same as observed in Allende, except oxidation increased the ID/IG (intensity ratio of the D band to the G band) in Saratov but decreased in Allende. This difference may be attributed to the different crystalline stages of carbon in both meteorites. The shifts in the Raman parameters to a discrete and/or more expanded region suggest that (1) oxidation changes the crystalline condition of graphitic carbon, (2) phase Q is not a dissolved site, and (3) the release of Q-gas is simply related to the rearrangement of the carbon structure during oxidation.

  17. Thermal metamorphism of primitive meteorites. VIII - Noble gases, carbon and sulfur in Allende /C3/ meteorite heated at 400-1000 C

    NASA Technical Reports Server (NTRS)

    Herzog, G. F.; Gibson, E. K., Jr.; Lipschutz, M. E.

    1979-01-01

    Noble gases, C and S, are lost from Allende samples heated for 1 week at temperatures of 400-1000 C in a low pressure environment. In the extreme, losses of He-3 and He-4 are about 100 x while for C, S and Ne, Ar and Kr isotopes and Xe-132 these are less than or equal to 10 x. Except for He, these losses are less severe than those of Bi or Tl from samples heated in the same runs. Significant He, Ne and Ar isotopic fractionation during heating indicates preferential outgassing of specific reservoirs. Next to He, Ar-40 is the most labile of those species considered here but still less so than Bi or Tl. L-group (but not H- or LL-group) chondrites may have lost mobile elements like Tl while being outgassed after late impact-associated heating. A less likely alternative involving a collateral relation between condensation conditions and depth in a parent object may also explain the L-group trend.

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

    SciTech Connect

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

    2015-05-14

    The systems studied in this work are gas-phase weakly bound adducts of the noble-gas (Ng) atoms with CCl{sub 4} and CF{sub 4}. 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-CCl{sub 4} and Ng-CF{sub 4} 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-CF{sub 4}, 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-CCl{sub 4}, 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 CCl{sub 4} 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 CCl{sub 4} while other geometries appear to play a minor to negligible role.

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

    PubMed

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

    2015-05-14

    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. PMID:25978888

  20. Metamorphic fluid origins in the Osborne Fe oxide-Cu-Au deposit, Australia: evidence from noble gases and halogens

    NASA Astrophysics Data System (ADS)

    Fisher, L. A.; Kendrick, M. A.

    2008-07-01

    The Osborne iron oxide-copper-gold (IOCG) deposit is hosted by amphibolite facies metasedimentary rocks and associated with pegmatite sheets formed by anatexis during peak metamorphism. Eleven samples of ore-related hydrothermal quartz and two pegmatitic quartz-feldspar samples contain similarly complex fluid inclusion assemblages that include variably saline (<12-65 wt% salts) aqueous and liquid carbon dioxide varieties that are typical of IOCG mineralisation. The diverse fluid inclusion types present in each of these different samples have been investigated by neutron-activated noble gas analysis using a combination of semi-selective thermal and mechanical decrepitation techniques. Ore-related quartz contains aqueous and carbonic fluid inclusions that have similar 40Ar/36Ar values of between 300 and 2,200. The highest-salinity fluid inclusions (47-65 wt% salts) have calculated 36Ar concentrations of approximately 1-5 ppb, which are more variable than air-saturated water (ASW = 1.3-2.7 ppb). These fluid inclusions have extremely variable Br/Cl values of between 3.8 × 10-3 and 0.3 × 10-3, and I/Cl values of between 27 × 10-6 and 2.4 × 10-6 (all ratios are molar). Fluid inclusions in the two pegmatite samples have similar 40Ar/36Ar values of ≤1,700 and an overlapping range of Br/Cl and I/Cl values. High-salinity fluid inclusions in the pegmatite samples have 2.5-21 ppb 36Ar, that overlap the range determined for ore-related samples in only one case. The fluid inclusions in both sample groups have 84Kr/36Ar and 129Xe/36Ar ratios that are mainly in the range of air and air-saturated water and are similar to mid-crustal rocks and fluids from other settings. The uniformly low 40Ar/36Ar values (<2,200) and extremely variable Br/Cl and I/Cl values do not favour a singular or dominant fluid origin from basement- or mantle-derived magmatic fluids related to A-type magmatism. Instead, the data are compatible with the involvement of metamorphic fluids that have interacted with anatectic melts to variable extents. The ‘metamorphic’ fluids probably represent a mixture of (1) inherited sedimentary pore fluids and (2) locally derived metamorphic volatilisation products. The lowest Br/Cl and I/Cl values and the ultra-high salinities are most easily explained by the dissolution of evaporites. The data demonstrate that externally derived magmatic fluids are not a ubiquitous component of IOCG ore-forming systems, but are compatible with models in which IOCG mineralisation is localised at sites of mixing between fluids of different origin.

  1. Noble gas trapping by laboratory carbon condensates

    NASA Technical Reports Server (NTRS)

    Niemeyer, S.; Marti, K.

    1982-01-01

    Trapping of noble gases by carbon-rich matter was investigated by synthesizing carbon condensates in a noble gas atmosphere. Laser evaporation of a solid carbon target yielded submicron grains which proved to be efficient noble gas trappers (Xe distribution coefficients up to 13 cu cm STP/g-atm). The carbon condensates are better noble gas trappers than previously reported synthetic samples, except one, but coefficients inferred for meteoritic acid-residues are still orders of magnitude higher. The trapped noble gases are loosely bound and elementally strongly fractionated, but isotopic fractionations were not detected. Although this experiment does not simulate nebular conditions, the results support the evidence that carbon-rich phases in meteorites may be carriers of noble gases from early solar system reservoirs. The trapped elemental noble gas fractionations are remarkably similar to both those inferred for meteorites and those of planetary atmospheres for earth, Mars and Venus.

  2. Fullerenes and the Nature of Planetary Gases

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  3. Noble gas studies in vapor-growth diamonds: Comparison with shock-produced diamonds and the origin of diamonds in ureilites

    SciTech Connect

    Matsuda, Junichi; Fukunaga, Kazuya; Ito, Keisuke )

    1991-07-01

    The authors synthesized vapor-trowth diamonds by two kinds of Chemical Vapor Deposition (CVD) using microwave (MWCVD) and hot filament (HFCVD) ionization of gases, and examined elemental abundances and isotopic compositions of the noble gases trapped in the diamonds. It is remarkable that strong differences existed in the noble gas concentrations in the two kinds of CVD diamonds: large amounts of noble gases were trapped in the MWCVD diamonds, but not in the HFCVD diamonds. The heavy noble gases (Ar to Xe) in the MWCVD diamonds were highly fractionated compared with those in the ambient atmosphere, and are in good agreement with the calculated fractionation patterns for plasma at an electron temperature of 7,000-9,000 K. These results strongly suggest that the trapping mechanism of noble gases in CVD diamonds is ion implantation during diamond growth. The degrees of fractionation of heavy noble gases were also in good agreement with those in ureilites. The vapor-growth hypothesis is discussed in comparison with the impact-shock hypothesis as a better model for the origin of diamonds in ureilites. The diamond (and graphite, amorphous carbon, too) may have been deposited on early condensates such as Re, Ir, W, etc. This model explains the chemical features of vein material in ureilites; the refractory siderophile elements are enriched in carbon and noble gases and low in normal siderophiles. The vapor-growth model is also compatible with the oxygen isotopic data of ureilites which suggests that nebular processes are primarily responsible for the composition of ureilites.

  4. 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.

  5. Modeling protein-small molecule interactions: structure and thermodynamics of noble gases binding in a cavity in mutant phage T4 lysozyme L99A.

    PubMed

    Mann, G; Hermans, J

    2000-09-29

    The complexes of phage T4 lysozyme L99A with noble gases have been studied by molecular dynamics simulation. In a long simulation of the complex with one Xe atom, the structure was found to undergo global conformation change involving a reversible opening and closing of the entrance to the substrate-binding site, during which the conformations of the N and C-terminal domains varied little. The distributions of Xe positions sampled in dynamics simulations were refined in terms of anisotropic Gaussian distributions via least-squares minimization of the difference between Fourier transforms. In addition, molecular transformation simulations have been applied in order to calculate the binding free energies of Xe, Kr and Ar relative to a standard state at a pressure of 1 bar. A single bound Xe is found to assume an equilibrium distribution over three adjacent preferred sites, while in a two-Xe complex, the two Xe atoms preferentially occupy two of these. The positions of the three sites agree closely with the positions of bound Xe determined in the refined crystal structure of a complex formed at a pressure of 8 bar Xe, and the calculated affinities agree well with the observed partial occupancies. At a pressure of 8 bar, a mixture of one-Xe and two-Xe complexes is present, and similarly for complexes with Kr and Ar, with single occupancy relatively more prevalent with Kr and Ar. (Binding of a third Xe atom is found to be quite unfavorable.) A comparison with simulation results for the binding of benzene to the same site leads to the conclusion that binding of Xe within cavities in proteins is common because of several favorable factors: (1) Xe has a large atomic polarizability; (2) Xe can be applied at a relatively high pressure, i.e. high chemical potential; (3) an unfavorable entropic term related to the need to orient the ligand in the binding site is absent. Finally, it is found that the model's binding energy of a water molecule in the cavity is insufficient to overcome the unfavorable binding entropy. PMID:10993736

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

    NASA Astrophysics Data System (ADS)

    Baldwin, S.; Das, J. P.

    2013-12-01

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

  7. Noble gases in the sediment pore water as proxies for physical transport processes and past environmental conditions in Lake Van (Turkey)

    NASA Astrophysics Data System (ADS)

    Tomonaga, Y.; Brennwald, M. S.; Kipfer, R.

    2012-04-01

    Since many decades unconsolidated sediments have been proposed as a potential archive for noble-gas records to reconstruct past environmental conditions in lakes and oceans. In addition, the accumulation of non-atmospheric noble-gas isotopes allows tracing the geochemical origin and transport processes of the pore fluids [7]. For instance, the abundance of terrigenic He isotopes reflects the residence time and transport dynamics of the dissolved species in the pore space. The 3He/4He ratio of terrigenic He can be used to constrain the geochemical origin of the pore fluids [3, 7]. However, methods for reliable and robust noble-gas analysis in pore water of unconsolidated sediments have been developed only recently [1, 6]. Lake Van (Turkey) is one of the largest terminal lakes and the largest soda lake on Earth. The physical conditions of the lake are known to react sensitively to changes in the hydrological cycle and to the environment of the lake catchment [2]. Therefore, the noble-gas record in the sediments of Lake Van have a great potential as an archive to reconstruct past climate evolution in eastern Anatolia where the atmospheric south-western jet stream intersects the northern branch of the subtropical high pressure belt [4]. Also, the basin of Lake Van is situated in a tectonically active region characterized by the presence of major faults and volcanos and is known to accumulate mantle fluids [3, 7]. Noble-gas isotopes are therefore expected to yield insights into the origin and transport processes of terrigenic fluids in the sediment pore space and their release into the water body [7]. In this study we present noble-gas and salinity data measured in the pore water of sediment samples collected in Lake Van. Noble-gas data from short cores (~ 2 m) taken at different sites throughout the lake basin are discussed from the point of view of the fluid transport in the pore space. In this context, we interpret the latest results from the noble-gas samples acquired in 2010 during the ICDP PaleoVan drilling operations from 220 m long cores [4, 5]. Noble-gas measurements are further linked to salinity measurements in terms of past lake level fluctuations and physical conditions of the water body of Lake Van.

  8. Noble Gas Temperature Proxy for Climate Change

    EPA Science Inventory

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

  9. Transferability and accuracy by combining dispersionless density functional and incremental post-Hartree-Fock theories: Noble gases adsorption on coronene/graphene/graphite surfaces.

    PubMed

    de Lara-Castells, María Pilar; Bartolomei, Massimiliano; Mitrushchenkov, Alexander O; Stoll, Hermann

    2015-11-21

    The accuracy and transferability of the electronic structure approach combining dispersionless density functional theory (DFT) [K. Pernal et al., Phys. Rev. Lett. 103, 263201 (2009)] with the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)], are validated for the interaction between the noble-gas Ne, Ar, Kr, and Xe atoms and coronene/graphene/graphite surfaces. This approach uses the method of increments for surface cluster models to extract intermonomer dispersion-like (2- and 3-body) correlation terms at coupled cluster singles and doubles and perturbative triples level, while periodic dispersionless density functionals calculations are performed to estimate the sum of Hartree-Fock and intramonomer correlation contributions. Dispersion energy contributions are also obtained using DFT-based symmetry-adapted perturbation theory [SAPT(DFT)]. An analysis of the structure of the X/surface (X = Ne, Ar, Kr, and Xe) interaction energies shows the excellent transferability properties of the leading intermonomer correlation contributions across the sequence of noble-gas atoms, which are also discussed using the Drude oscillator model. We further compare these results with van der Waals-(vdW)-corrected DFT-based approaches. As a test of accuracy, the energies of the low-lying nuclear bound states supported by the laterally averaged X/graphite potentials (X = (3)He, (4)He, Ne, Ar, Kr, and Xe) are calculated and compared with the best estimations from experimental measurements and an atom-bond potential model using the ab initio-assisted fine-tuning of semiempirical parameters. The bound-state energies determined differ by less than 6-7 meV (6%) from the atom-bond potential model. The crucial importance of including incremental 3-body dispersion-type terms is clearly demonstrated, showing that the SAPT(DFT) approach effectively account for these terms. With the deviations from the best experimental-based estimations smaller than 2.3 meV (1.9%), the accuracy of the combined DFT and post-HF incremental scheme is established for all the noble-gas atoms. With relative deviations smaller than 4% and 11%, good agreement is also achieved by applying the vdW-corrected DFT treatments PBE-D3 and vdW-DF2 for noble-gas atoms heavier than neon. PMID:26590547

  10. Transferability and accuracy by combining dispersionless density functional and incremental post-Hartree-Fock theories: Noble gases adsorption on coronene/graphene/graphite surfaces

    NASA Astrophysics Data System (ADS)

    de Lara-Castells, María Pilar; Bartolomei, Massimiliano; Mitrushchenkov, Alexander O.; Stoll, Hermann

    2015-11-01

    The accuracy and transferability of the electronic structure approach combining dispersionless density functional theory (DFT) [K. Pernal et al., Phys. Rev. Lett. 103, 263201 (2009)] with the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)], are validated for the interaction between the noble-gas Ne, Ar, Kr, and Xe atoms and coronene/graphene/graphite surfaces. This approach uses the method of increments for surface cluster models to extract intermonomer dispersion-like (2- and 3-body) correlation terms at coupled cluster singles and doubles and perturbative triples level, while periodic dispersionless density functionals calculations are performed to estimate the sum of Hartree-Fock and intramonomer correlation contributions. Dispersion energy contributions are also obtained using DFT-based symmetry-adapted perturbation theory [SAPT(DFT)]. An analysis of the structure of the X/surface (X = Ne, Ar, Kr, and Xe) interaction energies shows the excellent transferability properties of the leading intermonomer correlation contributions across the sequence of noble-gas atoms, which are also discussed using the Drude oscillator model. We further compare these results with van der Waals-(vdW)-corrected DFT-based approaches. As a test of accuracy, the energies of the low-lying nuclear bound states supported by the laterally averaged X/graphite potentials (X = 3He, 4He, Ne, Ar, Kr, and Xe) are calculated and compared with the best estimations from experimental measurements and an atom-bond potential model using the ab initio-assisted fine-tuning of semiempirical parameters. The bound-state energies determined differ by less than 6-7 meV (6%) from the atom-bond potential model. The crucial importance of including incremental 3-body dispersion-type terms is clearly demonstrated, showing that the SAPT(DFT) approach effectively account for these terms. With the deviations from the best experimental-based estimations smaller than 2.3 meV (1.9%), the accuracy of the combined DFT and post-HF incremental scheme is established for all the noble-gas atoms. With relative deviations smaller than 4% and 11%, good agreement is also achieved by applying the vdW-corrected DFT treatments PBE-D3 and vdW-DF2 for noble-gas atoms heavier than neon.

  11. Fabrication of nanoscale metal paths in oxide thin layers by noble-gas ion beams

    NASA Astrophysics Data System (ADS)

    Yuasa, Hiromi; Hara, Michiko; Fuji, Yoshihiko; Fukuzawa, Hideaki

    2013-02-01

    We investigated the fabrication process of a nanostructure with alumina insulator layer and nanoscale Cu paths punching through an alumina layer inserted between magnetic multilayers. Ion-beam-assisted oxidation was applied to an AlCu layer, where ion beams with three kinds of noble gases of different mass, Ne, Ar and Xe, were compared. The heavy gas overcame the trade-off between the increasing purity of nanoscale Cu paths and the decreasing oxygen defects of the alumina. It is considered that the high mobility of surface atoms in the AlCu layer brought about by the heavy-gas ion beam promotes segregation of alumina and Cu.

  12. Prediction of Superhalogen-Stabilized Noble Gas Compounds.

    PubMed

    Samanta, Devleena

    2014-09-18

    The discovery of HArF has generated renewed interest in the chemistry of noble gases, particularly their hydrides. Though many weak complexes of noble gases bound by van der Waals interactions are known, the number of halogenated noble gas compounds, HNgX (Ng = noble gas; X = halogen), where the noble gas atom is chemically bound, is limited. These molecules are metastable, and their specialty is that there is substantial ionic bonding between the noble gas atom and the halogen atom. In this Letter, it is shown using density functional theory and second-order Mller-Plesset perturbation theory that by replacing the halogen atoms by superhalogens (Y), whose electron affinities are much larger than those of halogens, more ionic bonds between Ng and Y can be attained. Moreover, the superhalogen-containing noble gas hydrides, HNgY, are more stable compared to their halogenated counterparts. PMID:26276326

  13. 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.

  14. Simulations of atmospheric pressure discharge in a high-voltage nanosecond pulse using the particle-in-cell Monte Carlo collision model in noble gases

    NASA Astrophysics Data System (ADS)

    Shi, Feng; Wang, Dezhen; Ren, Chunsheng

    2008-06-01

    Atmospheric pressure discharge nonequilibrium plasmas have been applied to plasma processing with modern technology. Simulations of discharge in pure Ar and pure He gases at one atmospheric pressure by a high voltage trapezoidal nanosecond pulse have been performed using a one-dimensional particle-in-cell Monte Carlo collision (PIC-MCC) model coupled with a renormalization and weighting procedure (mapping algorithm). Numerical results show that the characteristics of discharge in both inert gases are very similar. There exist the effects of local reverse field and double-peak distributions of charged particles' density. The electron and ion energy distribution functions are also observed, and the discharge is concluded in the view of ionization avalanche in number. Furthermore, the independence of total current density is a function of time, but not of position.

  15. Noble gases in 18 Martian meteorites and angrite Northwest Africa 7812—Exposure ages, trapped gases, and a re-evaluation of the evidence for solar cosmic ray-produced neon in shergottites and other achondrites

    NASA Astrophysics Data System (ADS)

    Wieler, R.; Huber, L.; Busemann, H.; Seiler, S.; Leya, I.; Maden, C.; Masarik, J.; Meier, M. M. M.; Nagao, K.; Trappitsch, R.; Irving, A. J.

    2016-02-01

    We present noble gas data for 16 shergottites, 2 nakhlites (NWA 5790, NWA 10153), and 1 angrite (NWA 7812). Noble gas exposure ages of the shergottites fall in the 1-6 Ma range found in previous studies. Three depleted olivine-phyric shergottites (Tissint, NWA 6162, NWA 7635) have exposure ages of ~1 Ma, in agreement with published data for similar specimens. The exposure age of NWA 10153 (~12.2 Ma) falls in the range of 9-13 Ma reported for other nakhlites. Our preferred age of ~7.3 Ma for NWA 5790 is lower than this range, and it is possible that NWA 5790 represents a distinct ejection event. A Tissint glass sample contains Xe from the Martian atmosphere. Several samples show a remarkably low (21Ne/22Ne)cos ratio < 0.80, as previously observed in a many shergottites and in various other rare achondrites. This was explained by solar cosmic ray-produced Ne (SCR Ne) in addition to the commonly found galactic cosmic ray-produced Ne, implying very low preatmospheric shielding and ablation loss. We revisit this by comparing measured (21Ne/22Ne)cos ratios with predictions by cosmogenic nuclide production models. Indeed, several shergottites, acalpulcoites/lodranites, angrites (including NWA 7812), and the Brachina-like meteorite LEW 88763 likely contain SCR Ne, as previously postulated for many of them. The SCR contribution may influence the calculation of exposure ages. One likely reason that SCR nuclides are predominantly detected in meteorites from rare classes is because they usually are analyzed for cosmogenic nuclides even if they had a very small (preatmospheric) mass and hence low ablation loss.

  16. σ-Aromatic cyclic M3(+) (M = Cu, Ag, Au) clusters and their complexation with dimethyl imidazol-2-ylidene, pyridine, isoxazole, furan, noble gases and carbon monoxide.

    PubMed

    Pan, Sudip; Saha, Ranajit; Mandal, Subhajit; Chattaraj, Pratim K

    2016-04-28

    The σ-aromaticity of M3(+) (M = Cu, Ag, Au) is analyzed and compared with that of Li3(+) and a prototype σ-aromatic system, H3(+). Ligands (L) like dimethyl imidazol-2-ylidene, pyridine, isoxazole and furan are employed to stabilize these monocationic M3(+) clusters. They all bind M3(+) with favorable interaction energy. Dimethyl imidazol-2-ylidene forms the strongest bond with M3(+) followed by pyridine, isoxazole and furan. Electrostatic contribution is considerably more than that of orbital contribution in these M-L bonds. The orbital interaction arises from both L → M σ donation and L ← M back donation. M3(+) clusters also bind noble gas atoms and carbon monoxide effectively. In general, among the studied systems Au3(+) binds a given L most strongly followed by Cu3(+) and Ag3(+). Computation of the nucleus-independent chemical shift (NICS) and its different extensions like the NICS-rate and NICS in-plane component vs. NICS out-of-plane component shows that the σ-aromaticity in L bound M3(+) increases compared to that of bare clusters. The aromaticity in pyridine, isoxazole and furan bound Au3(+) complexes is quite comparable with that in the recently synthesized Zn3(C5(CH3)5)3(+). The energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital also increases upon binding with L. The blue-shift and red-shift in the C-O stretching frequency of M3(CO)3(+) and M3(OC)3(+), respectively, are analyzed through reverse polarization of the σ- and π-orbitals of CO as well as the relative amount of OC → M σ donation and M → CO π back donation. The electron density analysis is also performed to gain further insight into the nature of interaction. PMID:26624276

  17. 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.

  18. The Thermochemical Stability of Ionic Noble Gas Compounds.

    ERIC Educational Resources Information Center

    Purser, Gordon H.

    1988-01-01

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

  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. Noble gas component organization in 14301

    NASA Technical Reports Server (NTRS)

    Bernatowicz, T. J.; Hohenberg, C. M.; Hudson, B.; Kennedy, B. M.; Podosek, F. A.; Laul, J. C.

    1980-01-01

    A study is conducted of the organization of noble gases in the Apollo 14 breccia 14301, giving particular attention to xenon from the extinct radionuclides I-129 and Pu-244. An essential ingredient of this work is the intercomparison between noble gases released in single-stage melts of grain size fractions and those released in stepwise extractions. This approach resolves 'functional' noble gas components, which are organized by siting, into the specific genetic contributions on the basis of the 'activation energies' for diffusive loss. The procedure makes it possible to resolve various genetic components on the basis of the chemical and structural differences in their specific locations. Consequently, distinctions can be made among components acquired by different processes and among components which have undergone different regolith histories.

  1. Noble Gas Partitioning Behaviour During Mantle Melting: A Possible Explanation for 'The He Paradox'?

    NASA Astrophysics Data System (ADS)

    Brooker, R. A.; Heber, V.; Kelley, S. P.; Wood, B. J.

    2003-12-01

    New UVLAMP measurements of experimental noble gas crystal/melt partitioning values (including He) suggest reasonably incompatible behaviour for both olivine and cpx and no significant fractionation of noble gases relative to one another. This is consistent with models of noble gas incorporation at crystal lattice sites in both crystals (1). However the determined D values of approximately 8 x10-4 for cpx and 5 x10-3 for olivine suggest a small but significant amount of noble gas might be retained in the mantle after melting. It is also apparent that He is three orders of magnitude less incompatible than U and Th in olivine. As opx is predicted to show similar characteristic to olivine, melting to produce a highly depleted harzbugitic (low-cpx) mantle would involve the preferential removal of U+Th relative to He. This in turn would allow a relatively undisturbed primordial/radiogenic 3He/4He ratio to be retained in association with low He abundance. Thus, recycling of previously depleted mantle into the source region of 'hot spots' provides one possible explanation for the paradox of high 3/4 He ratios previously thought to indicate an undegassed, primordial lower mantle reservoir, with low He abundance indicating a degassed source (2). Preliminary UVLAMP depth profiles for noble gas diffusion in mantle minerals confirm that although sub-solidus diffusive removal of He relative to other noble gases from a gas-rich mantle plum is theoretically possible, the short distances involved are unlikely to produce an effect that can be sustained though a hot spot melting event. The slow diffusion rates and lack of fractionation of noble gases in our partitioning experiments suggests that low He/Ar (and Ne/Ar) ratios observed at hot spots are most likely to be features inherited from the source, or subsequently imposed by some shallow level process. In our partitioning experiments, it proved surprisingly difficult to grow olivine crystals that are free of bubbles, even from volatile undersaturated melts. These bubbles nucleate on the crystal surface and can become included as the crystals grow. Although inclusions can be avoided using our micro-analytical technique, their bulk effect is to produce high crystal+bubble/melt D values and fractionation of light from heavy noble gases due to decreasing solubility in the melt for the latter. If such bubble capture occurs in nature as suggested by (3), the cumulative crystal rock would show enrichment in light noble gases and the residual melt will be depleted. This effect is similar to degassing but may be independent of saturation and depth of emplacement and decoupled from other volatile behaviour. The removed volatiles will also be retained in the cumulate rock rather than degassed. Differences in crystal growth processes and bubble trapping during MORB and IOB emplacement could contribute towards different He/Ar and Ne/Ar ratios. 1. R.A. Brooker et al., Nature 423, 738-741. 2003 2. D.L. Anderson, Proc. Natl. Acad. Sci. USA 95, 4822-4827. 1998 3. J.H. Natland, J. Pet. 44, 421-456. 2003

  2. Simulations of noble gases adsorbed on graphene

    NASA Astrophysics Data System (ADS)

    Maiga, Sidi; Gatica, Silvina

    2014-03-01

    We present results of Grand Canonical Monte Carlo simulations of adsorption of Kr, Ar and Xe on a suspended graphene sheet. We compute the adsorbate-adsorbate interaction by a Lennard-Jones potential. We adopt a hybrid model for the graphene-adsorbate force; in the hybrid model, the potential interaction with the nearest carbon atoms (within a distance rnn) is computed with an atomistic pair potential Ua; for the atoms at r>rnn, we compute the interaction energy as a continuous integration over a carbon uniform sheet with the density of graphene. For the atomistic potential Ua, we assume the anisotropic LJ potential adapted from the graphite-He interaction proposed by Cole et.al. This interaction includes the anisotropy of the C atoms on graphene, which originates in the anisotropic π-bonds. The adsorption isotherms, energy and structure of the layer are obtained and compared with experimental results. We also compare with the adsorption on graphite and carbon nanotubes. This research was supported by NSF/PRDM (Howard University) and NSF (DMR 1006010).

  3. Noble-gas-rich separates from the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Ott, U.; Mack, R.; Chang, S.

    1981-01-01

    Predominantly carbonaceous HF/HCl-resistant residues from the Allende meteorite are studied. Samples are characterized by SEM/EDXA, X-ray diffraction, INAA, C, S, H, N, and noble gas analyses. Isotopic data for carbon show variations no greater than 5%, while isotopic data from noble gases confirm previously established systematics. Noble gas abundances correlate with those of C and N, and concomitant partial loss of C and normal trapped gas occur during treatments with oxidizing acids. HF/HCl demineralization of bulk meteorite results in similar fractional losses of C and trapped noble gases, which leads to the conclusion that various macromolecular carbonaceous substances serve as the main host phase for normal trapped noble gases and anomalous gases in acid-resistant residues, and as the carrier of the major part of trapped noble gases lost during HF/HCl demineralization. Limits on the possible abundances of dense mineralic host phases in the residues are obtained, and considerations of the nucleogenetic origin for CCF-XE indicate that carbonaceous host phases and various forms of organic matter in carbonaceous meteorites may have a presolar origin.

  4. Noble gas transport during devolatilization of oceanic crust

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Smye, A.; Shuster, D. L.; Parman, S. W.; Kelley, S. P.; Hesse, M. A.; Cooper, R. F.

    2014-12-01

    Here we examine the role of slab dehydration in determining the elemental pattern of recycled noble gases. As a first step, we apply newly reported measurements of He-Ne-Ar (light noble gases) solubility and diffusivity in amphibole to parameterize a 1D diffusive-reaction transport model that simulates noble gas behavior during fluid loss from down-going oceanic crust. Recent experiments demonstrate that noble gases are highly soluble in ring-structured minerals, such as amphibole and other common hydrothermal products in slabs [1]. These results suggest that ring-structured minerals have the potential to strongly influence the budget of noble gases input into subduction zones and the elemental fractionations associated with volatile loss from slabs New measurements of He-Ne-Ar solubility in a suite of amphiboles have been completed utilizing the methodology described in [1]. These new measurements confirm that all light noble gases are highly soluble in amphibole, and that noble gas solubility correlates with the availability of unoccupied ring sites. New experimental measurements of He and Ne diffusivity have also been completed using a step-degassing approach at the Berkeley Geochronology Center. These measurements suggest that vacant ring sites in amphibole act to slow noble gas diffusion. We combine the newly acquired He and Ne diffusivity measurements with literature values for Ar diffusivity [2] to parameterize the diffusive-reaction transport model. Application of these data to the diffusive-reaction transport model yields several new insights. The relative mobility of Ne compared to Ar allows for efficient extraction of Ne from "hot" slabs by shallow depths (<50 km), while Ar is effectively retained to deeper depths, potentially past sub-arc conditions. Noble gas partition coefficients sharply increase with depth, following their increasing non-ideality in supercritical fluids, causing noble gases to partition back into minerals from any fluids retained in slabs at depth. The efficiency of noble gas extraction is particularly sensitive to the thermal regime and porosity of the slab (i.e. cold slabs with low porosity have the potential to recycle significant quantities noble gases). Refs: [1] Jackson et al. (2013). Nat.Geosci. 6, 562-565. [2] Harrison (1981). CMP 78, 324-331

  5. 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.

  6. Neutron detection by scintillation of noble-gas excimers

    NASA Astrophysics Data System (ADS)

    McComb, Jacob Collin

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

  7. Noble-gas-rich chondrules in an enstatite meteorite.

    PubMed

    Okazaki, R; Takaoka, N; Nagao, K; Sekiya, M; Nakamura, T

    2001-08-23

    Chondrules are silicate spherules that are found in abundance in the most primitive class of meteorites, the chondrites. Chondrules are believed to have formed by rapid cooling of silicate melt early in the history of the Solar System, and their properties should reflect the composition of (and physical conditions in) the solar nebula at the time when the Sun and planets were forming. It is usually believed that chondrules lost all their noble gases at the time of melting. Here we report the discovery of significant amounts of trapped noble gases in chondrules in the enstatite chondrite Yamato-791790, which consists of highly reduced minerals. The elemental ratios 36Ar/132Xe and 84Kr/132Xe are similar to those of 'subsolar' gas, which has the highest 36Ar/132Xe ratio after that of solar-type noble gases. The most plausible explanation for the high noble-gas concentration and the characteristic elemental ratios is that solar gases were implanted into the chondrule precursor material, followed by incomplete loss of the implanted gases through diffusion over time. PMID:11518959

  8. Relativistic Quantum Chemistry of Heavy Elements: Interatomic potentials and Lines Shift for Systems 'Alkali Elements-Inert Gases'

    SciTech Connect

    Glushkov, A. V.; Khetselius, O.; Gurnitskaya, E.; Loboda, A.; Mischenko, E.

    2009-03-09

    New relativistic approach, based on the gauge-invariant perturbation theory (PT) with using the optimized wave functions basis's, is applied to calculating the inter atomic potentials, hyper fine structure (hfs) collision shift for alkali atoms in atmosphere of inert gases. Data for inter atomic potentials, collision shifts of the Rb and Cs atoms in atmosphere of the inert gas He are presented.

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

    SciTech Connect

    McComb, Jacob C.; Al-Sheikhly, Mohamad; Coplan, Michael A.; Thompson, Alan K.; Vest, Robert E.; Clark, Charles W.

    2014-04-14

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

  10. Noble gas geochemistry in thermal springs

    SciTech Connect

    Kennedy, B.M.; Reynolds, J.H. ); Smith, S.P. )

    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.

  11. Noble gas diffusivity hindered by low energy sites in amphibole

    NASA Astrophysics Data System (ADS)

    Jackson, Colin R. M.; Shuster, David L.; Parman, Stephen W.; Smye, Andrew J.

    2016-01-01

    The diffusion kinetics of He and Ne in four amphibole specimens have been experimentally determined using stepwise degassing analysis of samples previously irradiated with energetic protons, and Arrhenius relationships have been fit to these data. The primary finding is that He and Ne diffusivities are systematically lower in amphiboles that have higher concentrations of unoccupied ring sites, suggesting that unoccupied ring sites act as traps for migrating noble gases. Ring site influence of noble gas diffusivity in amphiboles has substantial implications for 40Ar/39Ar thermochronology applied to these phases and the efficiency of noble gas recycling in subduction zones. These findings are consistent with the correlation between noble gas solubility and the concentration of unoccupied ring sites in amphibole (Jackson et al., 2013a, 2015) but are inconsistent with the ionic porosity model for noble gas diffusion (Fortier and Giletti, 1989; Dahl, 1996). Rather, these findings suggest that the topology of ionic porosity and absolute volume of ionic porosity compete in determining the rate at which noble gases diffuse.

  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 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...

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

    NASA Technical Reports Server (NTRS)

    Walsworth, Ronald L.

    2003-01-01

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

  15. Noble-gas-rich separates from ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Moniot, R. K.

    1980-01-01

    Acid-resistant residues were prepared by HCl-HF demineralization of three H-type ordinary chondrites: Brownfield 1937 (H3), Dimmitt (H3, 4), and Estacado (H6). These residues were found to contain a large proportion of the planetary-type trapped Ar, Kr, and Xe in the meteorites. The similarity of these acid residues to those from carbonaceous chondrites and LL-type ordinary chondrites suggests that the same phase carries the trapped noble gases in all these diverse meteorite types. Because the H group represents a large fraction of all meteorites, this result indicates that the gas-rich carrier phase is as universal as the trapped noble-gas component itself. When treated with an oxidizing etchant, the acid residues lost almost all their complement of noble gases.

  16. Noble-gas-rich separates from ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Moniot, R. K.

    1980-02-01

    Acid-resistant residues were prepared by HCl-HF demineralization of three H-type ordinary chondrites: Brownfield 1937 (H3), Dimmitt (H3, 4), and Estacado (H6). These residues were found to contain a large proportion of the planetary-type trapped Ar, Kr, and Xe in the meteorites. The similarity of these acid residues to those from carbonaceous chondrites and LL-type ordinary chondrites suggests that the same phase carries the trapped noble gases in all these diverse meteorite types. Because the H group represents a large fraction of all meteorites, this result indicates that the gas-rich carrier phase is as universal as the trapped noble-gas component itself. When treated with an oxidizing etchant, the acid residues lost almost all their complement of noble gases.

  17. Impact of biodiesel and renewable diesel on emissions of regulated pollutants and greenhouse gases on a 2000 heavy duty diesel truck

    NASA Astrophysics Data System (ADS)

    Na, Kwangsam; Biswas, Subhasis; Robertson, William; Sahay, Keshav; Okamoto, Robert; Mitchell, Alexander; Lemieux, Sharon

    2015-04-01

    As part of a broad evaluation of the environmental impacts of biodiesel and renewable diesel as alternative motor fuels and fuel blends in California, the California Air Resources Board's (CARB) Heavy-duty Diesel Emission Testing Laboratory conducted chassis dynamometer exhaust emission measurements on in-use heavy-heavy-duty diesel trucks (HHDDT). The results presented here detail the impact of biodiesel and renewable diesel fuels and fuel blends as compared to CARB ULSD on particulate matter (PM), regulated gases, and two greenhouse gases emissions from a HHDDT with a 2000 C15 Caterpillar engine with no exhaust after treatment devices. This vehicle was tested over the Urban Dynamometer Driving Schedule (UDDS) and the cruise portion of the California HHDDT driving schedule. Three neat blend stocks (soy-based and animal-based fatty acid methyl ester (FAME) biodiesels, and a renewable diesel) and CARB-certified ultra-low sulfur diesel (CARB ULSD) along with their 20% and 50% blends (blended with CARB ULSD) were tested. The effects of blend level on emission characteristics were discussed on g·km-1 basis. The results showed that PM, total hydrocarbon (THC), and carbon monoxide (CO) emissions were dependent on driving cycles, showing higher emissions for the UDDS cycles with medium load than the highway cruise cycle with high load on per km basis. When comparing CARB ULSD to biodiesels and renewable diesel blends, it was observed that the PM, THC, and CO emissions decreased with increasing blend levels regardless of the driving cycles. Note that biodiesel blends showed higher degree of emission reductions for PM, THC, and CO than renewable diesel blends. Both biodiesels and renewable diesel blends effectively reduced PM emissions, mainly due to reduction in elemental carbon emissions (EC), however no readily apparent reductions in organic carbon (OC) emissions were observed. When compared to CARB ULSD, soy- and animal-based biodiesel blends showed statistically significant increases in nitrogen oxides (NOx) emissions for 50% or higher biodiesel blends. The 20% blends of the biodiesels showed no statistically significant effect on NOx emissions on any cycle. In contrast, renewable diesel slightly decreased NOx emissions and the degree of reduction was statistically significant for 50% or higher blends over the UDDS cycle, but not at the 20% blends. The highway cruise cycles did not show a statistically strong NOx emission trend with increasing blend level of renewable diesel. Biodiesel and renewable fuel impacts on two greenhouse gases, CO2 and N2O emissions were of lower magnitude when compared to other regulated pollutants emissions, showing a change in their emissions within approximately ±3% from the CARB ULSD.

  18. Delivery of micrometeoritic greenhouse gases and "smoke" particles during the post-lunar "late heavy bombardment" of the Earth

    NASA Astrophysics Data System (ADS)

    Maurette, M.; Brack, A.; Duprat, J.; Engrand, C.

    (1) Processed micrometeorites in Astrobiology. In previous studies, we considered the contribution of unmelted micrometeorites in astrobiology. We now argue that even processed micrometeorites that are destroyed upon atmospheric entry could have participated in the birth of life on Earth. Unweathered micrometeorites from our new "Concordia-collection" show high sulfur contents of about 5%. With the simple assumption that all sulfur from volatilized micrometeorites is initially oxidized during atmospheric entry, like organic carbon, our model predicts an enormous initial input rate of SO2 in the thermosphere (˜ 1016 g/yr) that lasted for, at least, 100 Myr after the Moon forming impact (this impact blew off the primitive atmosphere). This post-lunar SO2 input was probably quickly transformed into stratospheric sulfate aerosols that were finally deposited in the early oceans. A plausible reaction pathway to eliminate such an excess of sulfates requires the likely existence of abundant early hydrothermal sources, converting sulfates dissolved in water into huge deposits of iron sulfides and exhalations of H2S, as in contemporary sources. In the "sulfide world" promoted by Wächtershäuser, sulfides, FeS and H2S, can reduce CO2 to organic sulfides in the form of thiols, as demonstrated in laboratory simulation experiments. Thiols can lead to thioesters, which probably behaved as activating agents in prebiotic chemistry, according to de Duve; (2) Post-lunar greenhouse effects. It is likely that the greenhouse gases CO2 and H2O released from the Earth's interior counterbalanced the "faint" early Sun luminosity. But these gases were blown off by the Moon forming impact. However, during the first ˜ 100 Myr of the post-lunar period, we predict enormous input rates of three powerful micrometeoritic greenhouse gases (SO2, H2O, CO2). They should have produced a marked heating of the Earth's surface, which had to be counterbalanced by a strong cooling. Hunten and collaborators proposed that over the last ˜ 10 Myr, climatic variations might have been triggered by variable input of "meteoritic" smoke particles. This concept can be extended to "micrometeoritic" smoke particles injected into the thermosphere by about 50% of the incoming flux of micrometeorites. We predict that the equilibrium optical thickness of this upper smoky cloud was about ≈ 120 μ m. Consequently, it should have reflected sunlight, thus contributing to counterbalance the heating effect of micrometeoritic greenhouse gases.

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

    PubMed

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

    2014-01-01

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

  20. 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

  1. The Noble Savage.

    ERIC Educational Resources Information Center

    Greer, Sandy

    1993-01-01

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

  2. Defining Noble Gas Partitioning for Carbon Capture and Storage Environments

    NASA Astrophysics Data System (ADS)

    Warr, O.; Masters, A.; Rochelle, C.; Ballentine, C. J.

    2014-12-01

    For viable CCS implementation variables such as CO2 dissolution rates, reactions with the host rock and the extent of groundwater interaction must be accurately constrained. Noble gases play an important role in these systems [e.g. 1,2]. Their application, however, requires accurate Henry's constants within dense CO2-H2O systems. Current interpretations use pure noble gas-H2O partitioning data [3,4] and assume CO2-noble gas interactions are negligible, even at high (>700 kg/m3) CO2 densities [2]. To test this assumption we experimentally determined noble gas CO2-H2O partitioning for the 170-656 kg/m3 CO2 density range; representative of most CCS environments. Contrary to assumption, CO2 density significantly affected noble gas partition coefficients. For helium, increasing CO2 density resulted in a negative deviation trend from CO2-free values whilst for argon, krypton and xenon strong, positive deviations were observed. At 656 kg/m3 these deviations were -35%, 74%, 114% and 321% respectively. This is interpreted as the CO2 phase acting as a polar solvent inducing polarisation in the noble gases. Deviation trends are well defined using a 2nd order polynomial. The effect of a dense CO2 phase can now be incorporated into existing noble gas models. We also present results from a Gibbs-Ensemble Monte Carlo molecular simulation to model partitioning for this binary system. This fundamental technique makes predictions based on the pair-potentials of interaction between the molecules. Here it gives the phase compositions and Henry coefficients for noble gases. With a proven ability in accurately replicating both the CO2-H2O system and low pressure noble gas Henry constants the focus is now on fully optimising the model to match high pressure observations. [1] Gilfillan et al. (2009) Nature 458 614-618 [2] Gilfillan et al. (2008) GCA 72 1174-1198 [3] Crovetto et al. (1982) J.Chem.Phys. 76 1077-1086 [4] Ballentine et al. in Porcelli et al. (eds.) (2002) Rev.Min.Geo. 47 539-614.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

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

  5. Greenhouse Gases

    MedlinePlus

    ... are greenhouse gases? Many chemical compounds present in Earth's atmosphere behave as 'greenhouse gases'. These are gases ... direct sunlight (relative shortwave energy) to reach the Earth's surface unimpeded. As the shortwave energy (that in ...

  6. 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

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

    NASA Technical Reports Server (NTRS)

    Walsworth, Ronald L.

    2001-01-01

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

  8. Experimental studies and model analysis of noble gas fractionation in porous media

    USGS Publications Warehouse

    Ding, Xin; Kennedy, B. Mack.; Evans, William C.; Stonestrom, David A.

    2016-01-01

    The noble gases, which are chemically inert under normal terrestrial conditions but vary systematically across a wide range of atomic mass and diffusivity, offer a multicomponent approach to investigating gas dynamics in unsaturated soil horizons, including transfer of gas between saturated zones, unsaturated zones, and the atmosphere. To evaluate the degree to which fractionation of noble gases in the presence of an advective–diffusive flux agrees with existing theory, a simple laboratory sand column experiment was conducted. Pure CO2 was injected at the base of the column, providing a series of constant CO2 fluxes through the column. At five fixed sampling depths within the system, samples were collected for CO2 and noble gas analyses, and ambient pressures were measured. Both the advection–diffusion and dusty gas models were used to simulate the behavior of CO2 and noble gases under the experimental conditions, and the simulations were compared with the measured depth-dependent concentration profiles of the gases. Given the relatively high permeability of the sand column (5 ´ 10−11 m2), Knudsen diffusion terms were small, and both the dusty gas model and the advection–diffusion model accurately predicted the concentration profiles of the CO2 and atmospheric noble gases across a range of CO2 flux from ?700 to 10,000 g m−2 d−1. The agreement between predicted and measured gas concentrations demonstrated that, when applied to natural systems, the multi-component capability provided by the noble gases can be exploited to constrain component and total gas fluxes of non-conserved (CO2) and conserved (noble gas) species or attributes of the soil column relevant to gas transport, such as porosity, tortuosity, and gas saturation.

  9. 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 Galpagos Islands. The second one displays a mass-dependent pattern, a pattern first observed in Michigan rainwater samples. Most samples point to equilibration temperatures at ~0C 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.

  10. Appraisal of transport and deformation in shale reservoirs using natural noble gas tracers

    SciTech Connect

    Heath, Jason E.; Kuhlman, Kristopher L.; Robinson, David G.; Bauer, Stephen J.; Gardner, William Payton

    2015-09-01

    This report presents efforts to develop the use of in situ naturally-occurring noble gas tracers to evaluate transport mechanisms and deformation in shale hydrocarbon reservoirs. Noble gases are promising as shale reservoir diagnostic tools due to their sensitivity of transport to: shale pore structure; phase partitioning between groundwater, liquid, and gaseous hydrocarbons; and deformation from hydraulic fracturing. Approximately 1.5-year time-series of wellhead fluid samples were collected from two hydraulically-fractured wells. The noble gas compositions and isotopes suggest a strong signature of atmospheric contribution to the noble gases that mix with deep, old reservoir fluids. Complex mixing and transport of fracturing fluid and reservoir fluids occurs during production. Real-time laboratory measurements were performed on triaxially-deforming shale samples to link deformation behavior, transport, and gas tracer signatures. Finally, we present improved methods for production forecasts that borrow statistical strength from production data of nearby wells to reduce uncertainty in the forecasts.

  11. Optimizing Noble Gas-Water Interactions via Monte Carlo Simulations.

    PubMed

    Warr, Oliver; Ballentine, Chris J; Mu, Junju; Masters, Andrew

    2015-11-12

    In this work we present optimized noble gas-water Lennard-Jones 6-12 pair potentials for each noble gas. Given the significantly different atomic nature of water and the noble gases, the standard Lorentz-Berthelot mixing rules produce inaccurate unlike molecular interactions between these two species. Consequently, we find simulated Henry's coefficients deviate significantly from their experimental counterparts for the investigated thermodynamic range (293-353 K at 1 and 10 atm), due to a poor unlike potential well term (εij). Where εij is too high or low, so too is the strength of the resultant noble gas-water interaction. This observed inadequacy in using the Lorentz-Berthelot mixing rules is countered in this work by scaling εij for helium, neon, argon, and krypton by factors of 0.91, 0.8, 1.1, and 1.05, respectively, to reach a much improved agreement with experimental Henry's coefficients. Due to the highly sensitive nature of the xenon εij term, coupled with the reasonable agreement of the initial values, no scaling factor is applied for this noble gas. These resulting optimized pair potentials also accurately predict partitioning within a CO2-H2O binary phase system as well as diffusion coefficients in ambient water. This further supports the quality of these interaction potentials. Consequently, they can now form a well-grounded basis for the future molecular modeling of multiphase geological systems. PMID:26452070

  12. 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

  13. 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.

  14. 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.

  15. The MSFC Noble Gas Research Laboratory (MNGRL): A NASA Investigator Facility

    NASA Technical Reports Server (NTRS)

    Cohen, Barbara

    2016-01-01

    Noble-gas isotopes are a well-established technique for providing detailed temperature-time histories of rocks and meteorites. We have established the MSFC Noble Gas Research Laboratory (MNGRL) at Marshall Space Flight Center to serve as a NASA investigator facility in the wake of the closure of the JSC laboratory formerly run by Don Bogard. The MNGRL lab was constructed to be able to measure all the noble gases, particularly Ar-Ar and I-Xe radioactive dating to find the formation age of rocks and meteorites, and Ar/Kr/Ne cosmic-ray exposure ages to understand when the meteorites were launched from their parent planets.

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

    SciTech Connect

    Astapenko, V. A. Svita, S. Yu.

    2014-11-15

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

  17. 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.

  18. 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).

  19. Noble metals in oncology.

    PubMed

    Markowska, Anna; Kasprzak, Bartosz; Jaszczy?ska-Nowinka, Karolina; Lubin, Jolanta; Markowska, Janina

    2015-01-01

    Worldwide research groups are searching for anticancer compounds, many of them are organometalic complexes having platinum group metals as their active centers. Most commonly used cytostatics from this group are cisplatin, carboplatin and oxaliplatin. Cisplatin was used fot the first time in 1978, from this time many platinum derivatives were created. In this review we present biological properties and probable future clinical use of platinum, gold, silver, iridium and ruthenium derivatives. Gold derivative Auranofin has been studied extensively. Action of silver nanoparticles on different cell lines was analysed. Iridium isotopes are commonly used in brachyterapy. Ruthenium compound new anti-tumour metastasis inhibitor (NAMI-A) is used in managing lung cancer metastases. Electroporation of another ruthenium based compound KP1339 was also studied. Most of described complexes have antiproliferative and proapoptotic properties. Further studies need to be made. Nevertheless noble metal based chemotherapheutics and compounds seem to be an interesting direction of research. PMID:26557773

  20. Noble metals in oncology

    PubMed Central

    Markowska, Anna; Jaszczyńska-Nowinka, Karolina; Lubin, Jolanta; Markowska, Janina

    2015-01-01

    Worldwide research groups are searching for anticancer compounds, many of them are organometalic complexes having platinum group metals as their active centers. Most commonly used cytostatics from this group are cisplatin, carboplatin and oxaliplatin. Cisplatin was used fot the first time in 1978, from this time many platinum derivatives were created. In this review we present biological properties and probable future clinical use of platinum, gold, silver, iridium and ruthenium derivatives. Gold derivative Auranofin has been studied extensively. Action of silver nanoparticles on different cell lines was analysed. Iridium isotopes are commonly used in brachyterapy. Ruthenium compound new anti-tumour metastasis inhibitor (NAMI-A) is used in managing lung cancer metastases. Electroporation of another ruthenium based compound KP1339 was also studied. Most of described complexes have antiproliferative and proapoptotic properties. Further studies need to be made. Nevertheless noble metal based chemotherapheutics and compounds seem to be an interesting direction of research. PMID:26557773

  1. 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.

  2. 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.

  3. Fluorescent noble metal nanoclusters

    NASA Astrophysics Data System (ADS)

    Zheng, Jie

    Water-soluble fluorescent metallic clusters at sizes comparable to the Fermi wavelength of an electron (˜0.5 nm for gold and silver) were created and their photophysical properties were investigated at the bulk and single molecule levels. We employed biocompatible dendrimer and peptide to prepare a series of strong fluorescent gold and silver clusters with chemical or photo reduction methods. Facilitated by the well-defined dendrimer size, electrospray ionization mass spectrometry indicates that the fluorescent silver nanocluster size ranges from 2 to 8 Ag atoms. The correlation of emission energy with the number of atoms, N, in each gold nanocluster is quantitatively fit for the smallest nanoclusters with no adjustable parameters by the simple scaling relation of EFermi/N1/3, in which EFermi is the Fermi energy of bulk gold. The transition energy scaling inversely with cluster radius indicates that electronic structure can be well described with the spherical jellium model and further demonstrates that these nanomaterials are "multi-electron artificial atoms". Fluorescence from these small metal clusters can be considered protoplasmonic, molecular transitions of the free conduction electrons before the onset of collective dipole oscillations occurring when a continuous density of states is reached. In addition, very strong single molecular Stokes and anti-Stokes Raman enhancement by fluorescent silver clusters was observed. Pushing to larger sizes, we also created ˜2nm diameter glutathione encapsulated luminescent gold nanoparticles. Distinct from similarly sized but nonluminescent gold nanoparticles, these 2 nm gold nanoparticles show bright, long lifetime emission but no plasmon absorption. The emission might arise from charge transfer between gold atoms and the thiol ligand. Providing the "missing link" between atomic and nanoparticle behavior in noble metals, these highly fluorescent, water-soluble gold and silver nanoclusters offer complementary transition energy size scalings at smaller dimensions than do semiconductor quantum dots. The unique discrete excitation and emission and strong Stokes and anti-Stokes Raman enhancement coupled with facile creation in aqueous solution open new opportunities for noble metal nanoclusters as biological labels, energy transfer pairs, and other light emitters in nanoscale electronics.

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

    PubMed

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

    2006-11-01

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

  5. Signal-to-noise ratio comparison of encoding methods for hyperpolarized noble gas MRI

    NASA Technical Reports Server (NTRS)

    Zhao, L.; Venkatesh, A. K.; Albert, M. S.; Panych, L. P.

    2001-01-01

    Some non-Fourier encoding methods such as wavelet and direct encoding use spatially localized bases. The spatial localization feature of these methods enables optimized encoding for improved spatial and temporal resolution during dynamically adaptive MR imaging. These spatially localized bases, however, have inherently reduced image signal-to-noise ratio compared with Fourier or Hadamad encoding for proton imaging. Hyperpolarized noble gases, on the other hand, have quite different MR properties compared to proton, primarily the nonrenewability of the signal. It could be expected, therefore, that the characteristics of image SNR with respect to encoding method will also be very different from hyperpolarized noble gas MRI compared to proton MRI. In this article, hyperpolarized noble gas image SNRs of different encoding methods are compared theoretically using a matrix description of the encoding process. It is shown that image SNR for hyperpolarized noble gas imaging is maximized for any orthonormal encoding method. Methods are then proposed for designing RF pulses to achieve normalized encoding profiles using Fourier, Hadamard, wavelet, and direct encoding methods for hyperpolarized noble gases. Theoretical results are confirmed with hyperpolarized noble gas MRI experiments. Copyright 2001 Academic Press.

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

    DOEpatents

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

    1997-09-23

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

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

    DOEpatents

    Baker, John D.; Meikrantz, David H.; Tuggle, Dale G.

    1997-01-01

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

  8. 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.

  9. Noble gases in hydrothermal plumes of Loihi Seamount

    NASA Astrophysics Data System (ADS)

    Kodera, Masako; Igarashi, George; Ozima, Minoru

    1988-02-01

    Seawater samples from hydrothermal plumes of Loihi Seamount show very high 3He/ 4He ratios (up to 15.8 × 10 -6) and 4He/ 20Ne ratios higher than that of air-saturated seawater (ASSW). The 3He/ 4He ratio in the source from which the helium is released into the seawater is estimated as (23.1 ± 2.3) × 10 -6 from the correlation plot of 3He/ 20Ne vs. 4He/ 20Ne. The 3He/heat ratio at Loihi is 5-49 times higher than that at the Galapagos Rift and at 21°N EPR. The difference may be attributed to the differences in the structure of the mantle beneath hot spots and the mid-ocean ridge, the former representing the deeper mantle region and the latter the shallower, depleted mantle. These observations are consistent with the view that helium in hydrothermal plumes of Loihi Seamount was derived from a deeper mantle region via a hot spot, where more primordial helium is still preserved.

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

    NASA Technical Reports Server (NTRS)

    Cess, R.; Owen, T.

    1973-01-01

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

  11. 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…

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

    PubMed

    Mondal, Sukanta; Chattaraj, Pratim Kumar

    2014-09-01

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

  13. Helium Solubility in Cyclosilicates and Implications for Noble Gas Recycling

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Kelley, S. P.; Cooper, R. F.; Parman, S. W.

    2011-12-01

    It is commonly assumed that noble gases strictly flux from the mantle to the atmosphere, with negligible recycling, because noble gases are thought to be extremely insoluble in all minerals. To test this hypothesis, we have experimentally determined the He solubility in a suite of cyclosilicate minerals: beryl, tourmaline and cordierite. The experiments were run in a gas pressure vessel. Run products were analyzed by UV laser ablation, noble gas mass spectrometry. He has a remarkably high solubility (>1000 ppm/1.8 kbar PHe) in cyclosilicates with nominally vacant six-member Si-Al-tetrahedra rings. Cyclosilicates with nominally occupied ring sites have substantially lower solubility. This suggests that He dissolution is facilitated by unfilled six-member rings. If true, He should have a high solubility in other minerals that include ring sites, such as phyllosilicates and amphiboles. Subduction zones commonly recycle these minerals, providing a possible mechanism for recycling of noble gases back into the mantle. Gem quality, natural, polished crystals of each mineral were placed into graphite capsules. Pure He gas was used as the pressure medium (1800 bar), allowing for precise control of PHe. Temperatures were held at 750 C and the experimental durations were 8 hours. A capsule of hydrated MgO powder was loaded in the TZM to maintain a non-zero fugacity of water during the experiment. Close visual inspection of the run products gave no indication of breakdown products. Depth profiles (10s of microns) of the mineral faces were completed using a 193 nm excimer laser. Multiple measurements were made on each phase. He concentrations were homogenous, both vertically and horizontally, indicating a close approach to equilibrium and absence of inclusions. Compared to tourmaline, we observe that He is >1000 and >100 times more soluble in cordierite and beryl, respectively. The ring sites, also known as A sites, in beryl and cordierite are nominally vacant, where as the ring sites in tourmaline, with the exception of foitite, are nominally full, suggesting the density of vacant rings in cyclosilicates is a primary control on He solubility. Ring sites are large (hosting LILEs) and have no net charge when vacant, making them an ideal candidate for hosting noble gases in general. This is also evidenced by high Ar solubilties (750 ppm/kbar PAr) measured in cubic leucite with similar lattice structures (1) and large He and Ar excesses reported for cyclosilicates (2). Many subduction zone minerals contain six-member Si-Al-tetrahedra rings (mica group, serpentine group, amphibole group and chlorite)(3,4). If recycled, these minerals could constitute a significant flux of noble gases back into the mantle. The magnitude and consequences of the flux will depend on the fugacity of noble gases during mineral formation and on how closed the system remains after eventual breakdown. 1. Wartho et al, Am Min, 2005 2. Damon and Kulp, Am Min, 1958 3. Schmidt and Poli, EPSL, 1998 4. Green et al, Nature, 2010

  14. Microdiamonds from Different Meteorite Types: N and Noble Gas Studies

    NASA Astrophysics Data System (ADS)

    Murty, S. V. S.; Sahijpal, S.; Fisenko, A. V.; Semjonova, L. P.; Shukolyukov, Yu. A.; Goswami, J. N.

    1993-07-01

    Microdiamonds isolated from CV3 and ordinary chondrites have been found to differ from those in CM2 meteorites in their N contents and low-temperature Xe-component (Xe-P3), even though the amounts of Xe-HL and the delta ^15N are similar [1,2]. We undertook a simultaneous study of N and noble gases in diamond-rich separates of Murchison (CM2), Efremovka (CV3), and Krymka (LL3.0) meteorites to identify the association of N and noble gas components in them and to characterize possible differences. Gases are extracted by combustion in 3 torr oxygen at low temperatures (up to 700 degrees C) and by pyrolysis at higher temperatures. Murchison: There are two peak releases. About 60-90% of all gases are released in the 550 degrees C step, which is characterized by the presence of Ne-A2, Xe-HL, and delta ^15N = -330 per mil. The second peak at 1200 degrees C gave delta ^15N = -567 per mil and showed a clear admixture of Ne-E and Xe-S (measured 20/22 = 4.2, 21/22 = 0.018, 130/132 = 0.309), indicating the presence of SiC. The low-temperature steps (400 degrees and 450 degrees C) gave Xe-P3 with an admixture of Xe-HL. These results are in agreement with our earlier analysis of another aliquot of Murchison C delta [3]. Efremovka (DE-4): There is a broad release in the 550 degrees C and 600 degrees C steps and a second peak at 1200 degrees C. We estimate that about 60% and 40% respectively of the sample are combusted at the two low- temperature steps. Although the 550 degrees C and 600 degrees C steps have similar gas amounts (except for Xe), other gases show significant differences in their isotopic compositions. The minimum delta ^15N of -290 per mil (600 degrees C) is much heavier than the typical C delta value of -330 per mil [1]. Xenon in both fractions is pure Xe-HL, while Kr is different [86/82 = 1.67 (550 degrees C) and 1.91 (600 degrees C)]. The 1200 degrees C fraction shows the presence of a small admixture of Ne-E, Xe-S, and Kr-S, but the delta ^15N (-127 per mil ) is very heavy compared to the corresponding value for Murchison. The amount of Xe-P3 (132 ~ 0.25 x 10^-8 cc/g) and N contents (~1200 ppm) are depleted in Efremovka diamonds as compared to Murchison (8 x 10^-8 cc/g, ~8000 ppm). The lowest-temperature steps (400 degrees C and 450 degrees C) comprising <2% of total Xe show a mixture of Xe-HL and a Xe-component that is itself a mixture of a planetary-like component and cosmogenic(?) Xe. No Xe- S signature was detected in this fraction. A carbonaceous phase hosting heavy nitrogen (delta ^15N >= 0 per mil ), excess ^82Kr, and cosmogenic Xe and having a combustion temperature in the range of 450 degrees-700 degrees C can explain these low-temperature components. Graphite is a possible phase as it is known to be present in the Efremovka separate DE-4 [4]. Krymka (KR-4): Because of the very small sample size (~0.01 mg) analyzed, only the peak release fraction at 550 degrees C could be studied for all gases. It shows signature of pure Xe-HL, Ne-A2, and delta ^15N = -216 per mil. The 1200 degrees C step clearly indicates the presence of Xe-S. Nitrogen content (~5700 ppm) and Xe-HL (132 ~ 32 x 10^-8 cc/g) in Krymka are comparable to those in CM2 microdiamonds. The uniqueness of the delta ^15N signature in microdiamonds (-330 per mil) needs further scrutiny in view of the heavier delta ^15N value found in diamond-rich separates from both Efremovka and Krymka, and more so in view of the recent observation of probable interstellar diamonds in dense molecular clouds [5]. The lower abundances of both N and Xe-P3 in Efremovka C delta, as compared to Murchison, is most likely a consequence of metamorphic processes. References: [1] Russel S. S. et al. (1991) Science, 254, 1188-1191. [2] Huss G. R. and Lewis R. S. (1991) Meteoritics, 26, 348. [3] Murty S. V. S. et al. (1992) Meteoritics, 27, 265. [4] Verchovsky A. B. et al. (1992) LPS XXIII, 1467-1468. [5] Allamandola L. J. et al. (1993) Science, 260, 64-66.

  15. Pressure broadening and shift of the cesium D{sub 2} transition by the noble gases and N{sub 2}, H{sub 2}, HD, D{sub 2}, CH{sub 4}, C{sub 2}H{sub 6}, CF{sub 4}, and {sup 3}He with comparison to the D{sub 1} transition

    SciTech Connect

    Pitz, Greg A.; Fox, Charles D.; Perram, Glen P.

    2010-10-15

    The pressure broadening and shift rates for the cesium D{sub 2} (6 {sup 2}P{sub 3/2} (<-) 6 {sup 2}S{sub 1/2}) transition with the noble gases and N{sub 2}, H{sub 2}, HD, D{sub 2}, CH{sub 4}, C{sub 2}H{sub 6}, CF{sub 4}, and {sup 3}He were obtained for pressures less than 300 Torr at a temperature of 40 deg. C by means of laser absorption spectroscopy. The collisional broadening rate {gamma}{sub L} for He, Ne, Ar, Kr, Xe, N{sub 2}, H{sub 2}, HD, D{sub 2}, CH{sub 4}, C{sub 2}H{sub 6}, CF{sub 4}, and {sup 3}He are 20.59, 9.81, 16.47, 15.54, 18.41, 19.18, 27.13, 28.24, 22.84, 25.84, 26.14, 17.81, and 22.35 MHz/Torr, respectively. The uncertainty in the broadening rates is typically less than 0.3%. The corresponding pressure-induced shift rates {delta} are 0.69, -2.58, -6.18, -6.09, -6.75, -6.20, -4.83, -4.49, -4.54, -8.86, -9.38, -6.47, and 0.60 MHz/Torr with an uncertainty of less than 0.04 MHz/Torr. With the exception of diatomic collision partners, the broadening rates for Cs D{sub 2} are 5%-15% less than the rates for Cs D{sub 1}. For light collision partners with a blue shift, the D{sub 1} is shifted more than the D{sub 2} line. The broadening cross sections for Cs and Rb are similar. However, the cross sections for K are about 70% larger and for Na, about 30% less.

  16. Nanopore sculpting with noble gas ions

    PubMed Central

    Cai, Qun; Ledden, Brad; Krueger, Eric; Golovchenko, Jene A.; Li, Jiali

    2011-01-01

    We demonstrate that 3 keV ion beams, formed from the common noble gasses, He, Ne, Ar, Kr, and Xe, can controllably “sculpt” nanometer scale pores in silicon nitride films. Single nanometer control of structural dimensions in nanopores can be achieved with all ion species despite a very wide range of sputtering yields and surface energy depositions. Heavy ions shrink pores more efficiently and make thinner pores than lighter ions. The dynamics of nanopore closing is reported for each ion species and the results are fitted to an adatom diffusion model with excellent success. We also present an experimental method for profiling the thickness of the local membrane around the nanopore based on low temperature sputtering and data is presented that provides quantitative measurements of the thickness and its dependence on ion beam species. PMID:21331305

  17. Noble gas trapping and fractionation during synthesis of carbonaceous matter. [in meteorites

    NASA Technical Reports Server (NTRS)

    Frick, U.; Mack, R.; Chang, S.

    1979-01-01

    An investigation of noble gas entrapment during synthesis of carbonaceous, macromolecular, and kerogen-like substances is presented. High molecular weight organic matter synthesized in aqueous condensation reactions contained little gas, and the composition was consistent with fractionation due to noble gas solubility in water; however, propane soot produced during a modified Miller-Urey experiment in an aritificial gas mixture contained high concentrations of trapped noble gases that displayed strong elemental fractionation from their reservoirs. It is concluded that theses experiemnts show that processes exist for synthesis of carbonaceous carriers that result in high noble gas concentrations and strong elemental fractionation at temperatures well above those required by absorption to achieve similar effects.

  18. 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.

  19. Effect of noble gas ion pre-irradiation on deuterium retention in tungsten

    NASA Astrophysics Data System (ADS)

    Cheng, L.; Zhao, Z. H.; De Temmerman, G.; Yuan, Y.; Morgan, T. W.; Guo, L. P.; Wang, B.; Zhang, Y.; Wang, B. Y.; Zhang, P.; Cao, X. Z.; Lu, G. H.

    2016-02-01

    Impurity seeding of noble gases is an effective way of decreasing the heat loads onto the divertor targets in fusion devices. To investigate the effect of noble gases on deuterium retention, tungsten targets have been implanted by different noble gas ions and subsequently exposed to deuterium plasma. Irradiation induced defects and deuterium retention in tungsten targets have been characterized by positron annihilation Doppler broadening and thermal desorption spectroscopy. Similar defect distributions are observed in tungsten irradiated by neon and argon, while it is comparatively low in the case of helium. The influence of helium pre-irradiation on deuterium trapping is found to be small based on the desorption spectrum compared with that of the pristine one. Neon and argon pre-irradiation leads to an enhancement of deuterium trapping during plasma exposure. The influence on deuterium retention is found to be argon > neon > helium when comparing at a similar crystal damage level.

  20. NOBLE GAS PRODUCTION FROM MERCURY SPALLATION AT SNS

    SciTech Connect

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

    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.

  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. Light Noble Gas Abundances in the Solar Wind Trapped by Chondritic Metal

    NASA Astrophysics Data System (ADS)

    Murer, Ch.; Bauer, H.; Wieler, R.

    1995-09-01

    The heavy solar noble gases Ar-Xe are retained elementally unfractionated relative to the incoming solar corpuscular radiation in lunar soils, as is shown by the flat profiles of Ar/Kr and Kr/Xe throughout closed system stepped etch extractions [1, 2]. In contrast, He/Ar and Ne/Ar reach present-day solar wind (SW) values only towards the end of the runs, indicating that the well known fractionating losses of solar He and Ne from lunar samples affect the shallowly sited SW component but not the more deeply implanted SEP (solar energetic particles). Rather flat He/Ar and Ne/Ar profiles were previously observed in stepped etchings of metallic Fe-Ni from solar-gas-rich meteorites [3-5], suggesting that Fe-Ni retains unfractionated He, Ne, and Ar from SW and SEP. Most runs showed some variation in elemental ratios, possibly due to i) experiment-induced fractionation, ii) the different penetration depths of the various gases [4], or iii) variable elemental abundances in SW and SEP. The results of a repeat run on a Fe-Ni separate from the H chondrite Fayetteville are shown in Fig. 1. The ^20Ne/^36Ar ratio is essentially flat and most values fall in the range of 48.5 +/- 7 of the modern SW [6]. The low values in the last three steps are presumably due to fractionated solar noble gases released from silicate impurities by copper-chloride in these final about 10 day extractions, since the lowest value is close to that in bulk samples. We thus cannot confirm a real variation of Ne/Ar with grain depth. The He/Ar pattern is similar to Ne/Ar except that the values of individual steps scatter considerably more. Flat profiles as in Fig. 1 strongly suggest that the average ratios deduced from meteoritic Fe-Ni (in some cases slightly corrected for e. g. contributions from silicates) yield good estimates of the relative light noble gas abundances in SW and SEP trapped by chondritic regoliths. Table 1 shows best values deduced from three chondrites (two runs each). These values differ by less than about 15% from those reported for present day SW and for solar gases in Acfer111 metal [4]. Remarkable is the good agreement of Ne/Ar deduced from meteorites with the SWC ratio, since the derivation of the latter value involved an about 40% correction for solar ^36Ar released from lunar soil and retrapped into the aluminium foils. References: [1] Wieler R. et al. (1993) LPS XXIV, 1519. [2] Wieler R. and Baur H. (1995) Astrophys. J., in press. [3] Murer Ch. et al. (1994) Meteoritics, 29, 506. [4] Pedroni A. and Begemann F. (1994) Meteoritics, 29, 632. [5] Murer Ch. (1995) Ph.D. thesis, ETH Zurich, #10964. [6] Cerutti H. (1974) Ph.D. thesis, Univ. Bern.

  3. 40 CFR 86.1214-85 - Analytical gases.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 19 2011-07-01 2011-07-01 false Analytical gases. 86.1214-85 Section... Emission Test Procedures for New Gasoline-Fueled, Natural Gas-Fueled, Liquefied Petroleum Gas-Fueled and Methanol-Fueled Heavy-Duty Vehicles § 86.1214-85 Analytical gases. (a) Analyzer gases. (1) Gases for...

  4. 40 CFR 86.1214-85 - Analytical gases.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 20 2013-07-01 2013-07-01 false Analytical gases. 86.1214-85 Section... Emission Test Procedures for New Gasoline-Fueled, Natural Gas-Fueled, Liquefied Petroleum Gas-Fueled and Methanol-Fueled Heavy-Duty Vehicles § 86.1214-85 Analytical gases. (a) Analyzer gases. (1) Gases for...

  5. 40 CFR 86.1214-85 - Analytical gases.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 20 2012-07-01 2012-07-01 false Analytical gases. 86.1214-85 Section... Emission Test Procedures for New Gasoline-Fueled, Natural Gas-Fueled, Liquefied Petroleum Gas-Fueled and Methanol-Fueled Heavy-Duty Vehicles § 86.1214-85 Analytical gases. (a) Analyzer gases. (1) Gases for...

  6. 40 CFR 86.1214-85 - Analytical gases.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Emission Test Procedures for New Gasoline-Fueled, Natural Gas-Fueled, Liquefied Petroleum Gas-Fueled and Methanol-Fueled Heavy-Duty Vehicles § 86.1214-85 Analytical gases. (a) Analyzer gases. (1) Gases for the... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Analytical gases. 86.1214-85...

  7. Development of a portable membrane contactor sampler for noble gas analyses of surface and groundwater samples

    NASA Astrophysics Data System (ADS)

    Matsumoto, T.; Han, L. H.; Jaklitsh, M.; Aggarwal, P. K.

    2012-04-01

    Noble gas isotopes dissolved in groundwater provide valuable information about climatic conditions during air-water exchange, as well as the residence time of groundwater and its renewal rate. The isotope composition of noble gases can also serve as geochemical fingerprints to decipher the origin of groundwater and its flow system. Conventionally, groundwater is sampled using a copper tube, which is subsequently degassed using a vacuum extraction system for isotope analysis by a mass spectrometer. Although this conventional and well-established way of sampling is widely recognised as being reliable and robust, a major drawback to this method is its size and weight. For example, our sampler consists of a copper tube of 10 mm diameter x 1000 mm length and a metal casing with pinch-off clamps with its total weight to be 2 kg each. A box of 24 samplers well exceeds 40 kg. Considering that sampling fields are not necessarily easily accessible by vehicle, taking hundreds of samples in the field is generally a tough task for everyone. There is a different type of sampler, which is comprised of a much smaller copper tube (6 mm in diameter and 100 mm long for our case) with clamps and a semi-permeable membrane filter. It is sunk into water and left there for dissolved gases to diffuse into the sampler until their concentrations in water become equilibrated with those in the tube. This diffusion sampler is small and easy to handle in the field; it has an advantage over conventional copper tubes, as the diffusion sampler collects gases so that there is no gas extraction process needed before isotope analysis. However, this method requires an equilibration time of 24 hours or more, which could result in lower time-efficiency for sampling work. In order to enable time-efficient and less-painstaking sampling of noble gases dissolved in surface and groundwater, we have developed a portable and self-powered sampling device specified to noble gas analysis by mass spectrometer, following the design of a similar device reported in literatures. The sampling device uses a commercially available membrane contactor which can separate gas phase from continuous from of water. We have examined its extraction performance by preparing several samples for different time spans. We found that our membrane contactor can extract heavier noble gases (Ar, Kr, and Xe) more efficient than lighter noble gases (He and Ne), implying that sorption of gas atoms to the membrane contactor is controlling the transport of noble gases through the membrane. We confirmed that extraction of about 60 min is sufficient for all noble gases reach equilibrium with those dissolved in the water. 3He/4He ratios and other noble gas isotope ratios showed no signs of isotope fractionation, suggesting that the device can be applicable for sampling of dissolved noble gases from the water aiming to the groundwater dating and paleo-climate reconstruction.

  8. Greenhouse Gases

    MedlinePlus

    ... were not for naturally occurring greenhouse gases, the earth would be too cold to support life as ... the greenhouse effect, the average temperature of the earth would be about -2°F rather than the ...

  9. Oxidant gases

    SciTech Connect

    Evans, M.J.

    1984-01-01

    The acute and chronic action of the oxidant gases ozone, nitrogen dioxide and oxygen on the morphological appearance of cells of the alveolar and bronchiolar epithelium is reviewed. Type I cells of the alveolar and ciliated cells of the bronchiolar epithelium appear to be sensitive targets for the oxidant gases. The degree of damage is influenced by age, nutritional status and the development of tolerance.

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  11. How Robust Is The Noble Gas Paleoclimate Proxy?

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  12. First-principles study of noble gas impurities and defects in UO2

    NASA Astrophysics Data System (ADS)

    Thompson, Alexander E.; Wolverton, C.

    2011-10-01

    We performed a series of density functional theory + U (DFT + U) calculations to explore the energetics of various defects in UO2, i.e., noble gases (He, Ne, Ar, Kr, Xe), Schottky defects, and the interaction between these defects. We found the following: (1) collinear antiferromagnetic UO2 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 UO2 (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.

  13. Bartlett's discovery of noble gas fluorides, a milestone in chemical history.

    PubMed

    Christe, Karl O

    2013-05-21

    In 1962, Neil Bartlett published a terse note in Proc. Chem. Soc. eradicating the long held dogma that noble gases are inert and cannot form stable compounds. This historical discovery has revolutionized our views on chemistry and has given rise to thousands of papers on noble gas chemistry. The fact that his proposed reaction product "Xe(+)[PtF6](-)" has eluded experimental detection for more than half a century and actually was a mixture of XeF(+) and Xe2F3(+) salts does not diminish the enormous impact of his discovery. A plausible explanation for the failures to observe "Xe(+)[PtF6](-)" experimentally is presented. PMID:23575727

  14. Noble Gas Analysis in the Quest to Find "Regolithic" Howardites

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    The howardite meteorites consist of approximately 200 polymict breccias of eucrite (basaltic) and diogenite (orthopyroxenitic) material (collectively, the HED group) that originate from the asteroid belt. Infrared reflectance spectroscopy of asteroids and laboratory studies of HEDs have indicated that the asteroid 4-Vesta is the likely parent body, and the partially-demolished south pole may be the source region. Asteroid regolith formation processes may be responsible for a number of observed petrological features including impact melt clasts, reworked clasts and mosaisicm. We have identified such features in a study of 30 howardites and polymict eucrites, and developed a regolith grading scheme based on petrology. However, the true regolithic nature of the howardite suite is not well defined, and previous research has suggested correlations between Ni contents of 300 - 1200 micron / g, a minimal variation in Al2O3 content around 8-9 wt% and the presence of solar wind noble gases are key hallmarks of an ancient regolith on Vesta . Through combined petrological, compositional and noble gas research, we aim to better understand howardite petrological diversity, regolith formation processes on parent asteroids, and to establish what defines a truly "regolithic" howardite. Our research will play an integral part in the interpretation of data gathered by the Dawn mission. Here we report the preliminary results from our noble gas analyses of four howardites: LEW 85313, EET 99408, MET 96500 and PCA 02066. Bulk major element compositional data have been collected, further petrological data for the HED group are reported by our colleagues, whilst trace-element analyses are underway. Our work will investigate the extent of whether previously described Ni, Al2O3 and noble gas characteristics are in fact indicative of a "regolithic" howardite.

  15. The noble gas systematics of late-orogenic H 2O-CO 2 fluids, Mt Isa, Australia

    NASA Astrophysics Data System (ADS)

    Kendrick, M. A.; Honda, M.; Oliver, N. H. S.; Phillips, D.

    2011-03-01

    The noble gases (He, Ne, Ar, Kr and Xe) are powerful geochemical tracers because they have distinctive isotopic compositions in the atmosphere, crust and mantle. This study illustrates how noble gases can be used to trace fluid origins in high-temperature metamorphic and mineralising environments; and at the same time provides new information on the composition of noble gases in deeper parts of the crust than have been sampled previously. We report data for H 2O and CO 2 fluid inclusions trapped at greenschist to amphibolite facies metamorphic conditions associated with three different styles of mineralisation and alteration in the Proterozoic Mt Isa Inlier of Australia. Sulphide fluid inclusions are dominated by crustal 4He. However, co-variations in fluid inclusion 20Ne/ 22Ne, 21Ne/ 22Ne, 40Ar/ 36Ar and 136Xe/ 130Xe indicate noble gases were derived from three or more reservoirs. In most cases, the fluid inclusions elemental noble gas ratios (e.g. Ne/Xe) are close to the ranges expected in sedimentary and crystalline rocks. However, the elemental ratios have been modified in some of the samples providing evidence for independent pulses of CO 2, and interaction of CO 2 with high-salinity aqueous fluids. Compositional variation is attributed to mixing of: (i) magmatic fluids (or deeply sourced metamorphic fluids) characterised by basement-derived noble gases with 20Ne/ 22Ne ˜ 8.4, 21Ne/ 22Ne ˜ 0.4, 40Ar/ 36Ar ˜ 40,000 and 136Xe/ 130Xe ˜ 8; (ii) basinal-metamorphic fluids with a narrow range of compositions including near-atmospheric values and (iii) noble gases derived from the meta-sedimentary host-rocks with 20Ne/ 22Ne ˜ 8-9.8, 21Ne/ 22Ne < 0.1, 40Ar/ 36Ar < 2500 and 136Xe/ 130Xe ˜ 2.2. These data provide the strongest geochemical evidence available for the involvement of fluids from two distinct geochemical reservoirs in Mt Isa's largest ore deposits. In addition the data show how noble gases in fluid inclusions can provide information on fluid origins, the composition of the crust's major lithologies, fluid-rock interactions and fluid-fluid mixing or immiscibility processes.

  16. 40 CFR 86.1514 - Analytical gases.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Otto-Cycle Heavy-Duty Engines, New Methanol-Fueled Natural Gas-Fueled, and Liquefied Petroleum Gas..., the analytical gases specified in 40 CFR part 1065, subpart H, shall be used. (c) If a CVS sampling system is used, the analytical gases specified in 40 CFR part 1065, subpart H, shall be used....

  17. Noble gas isotopes in mineral springs within the Cascadia Forearc, Wasihington and Oregon

    USGS Publications Warehouse

    McCrory, Patricia A.; Constantz, James E.; Hunt, Andrew G.

    2014-01-01

    This U.S. Geological Survey report presents laboratory analyses along with field notes for a pilot study to document the relative abundance of noble gases in mineral springs within the Cascadia forearc of Washington and Oregon. Estimates of the depth to the underlying Juan de Fuca oceanic plate beneath the sample sites are derived from the McCrory and others (2012) slab model. Some of these springs have been previously sampled for chemical analyses (Mariner and others, 2006), but none currently have publicly available noble gas data. Helium isotope values as well as the noble gas values and ratios presented below will be used to determine the sources and mixing history of these mineral waters.

  18. Diffusion in helium-noble gas mixtures I. Almost Lorentzian mixtures

    NASA Astrophysics Data System (ADS)

    Wahby, A. S. M.; Abdel-Rahman, M.; Los, J.

    1982-05-01

    Diffusion coefficients have been measured of almost Lorentzian binary mixtures of He and the noble gases Ne, Ar, Kr and Xe. Measurements have been performed in the temperature range from 237 K to 420 K. The agreement with other experimental data is very satisfactory. A comparison with experimental thermal diffusion data on the same mixtures shows that the relation for Lorentzian mixtures. α L= 2- {∂ In D 12}/{∂ In T }p is quite accurate for the heavier helium-noble gas mixtures. Comparison of the experimentally determined function 2- {∂ In D 12}/{∂ In T }p with theoretical calculations for several model potentials shows a semi-quantitative agreement between theory and experiment. The experimental curves indicate a great similarity between the interaction potentials of helium with the different noble gas atoms.

  19. 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.

  20. Interpreting noble-gas concentrations as proxies for salinity and temperature in the world's largest soda lake (Lake Van, Turkey)

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    In this work we present noble-gas concentration profiles measured in the water column and in the sediment pore water of the Earth's largest soda lake: Lake Van (eastern Anatolia, Turkey). The concentrations of noble gases (in particular Ar, Kr, and Xe) in the water body deviate significantly from the expected equilibrium concentrations calculated from the in situ temperature and salinity using existing solubility functions for seawater. The specific chemical composition of the water of the soda lake seems to be responsible for the observed deviations. Our measurements allow the identification and quantification of salinity factors that can be applied to correctly calculate the noble-gas equilibrium concentrations for the lake. These salinity factors provide a solid and robust empirical basis for the interpretation of noble-gas concentration signals measured in the sediment pore water of Lake Van in terms of palaeosalinity and palaeotemperature.

  1. Toxic gases.

    PubMed Central

    Matthews, G.

    1989-01-01

    An overview of the widespread use of gases and some volatile solvents in modern society is given. The usual circumstances in which undue exposure may occur are described. The most prominent symptoms and general principles of diagnosis and treatment are given and are followed by more specific information on the commoner, more toxic materials. While acute poisonings constitute the greater part of the paper, some indication of chronic disorders arising from repeated or prolonged exposure is also given. PMID:2687827

  2. Noble Gas Signatures in Groundwater and Rainwater on the Island of Maui, Hawaii - Developing a New Noble Gas Application in Fractured, Volcanic Systems

    NASA Astrophysics Data System (ADS)

    Castro, M. C.; Niu, Y.; Warrier, R. B.; Hall, C. M.; Gingerich, S. B.; Scholl, M. A.; Bouvier, L.

    2014-12-01

    Recent work in the Galapagos Islands suggests that noble gas temperatures (NGTs) in fractured groundwater systems reflect the temperature of the ground surface at the time of infiltration rather than the mean annual air temperature (MAAT) value as commonly assumed in sedimentary systems where NGTs are typically used as indicators of past climate. This suggests that noble gases in fractured areas may record seasonality, and thus, provide information about timing of recharge in addition to location. Calculation of NGTs assumes that rain-derived recharge at the water table is in equilibrium with ground air. Lack of noble gas equilibration with respect to surface conditions, however, was observed in high-altitude springs in the Galapagos Islands and in a rainwater pilot study in Michigan, supporting the NGT seasonality hypothesis. Developing this new NGT application will lead to a better understanding of fractured groundwater flow systems and will contribute to improved water resource management plans. This study, carried out on Maui, Hawaii, is meant to test these hypotheses while improving knowledge of this island's groundwater flow system where limited hydrologic data are available. Here, we present the first results of noble gas analyses from samples collected in springs, groundwater wells and rainwater on northeast Maui. Results show that like most Michigan rainwater samples, rainwater from Maui is in disequilibrium with surface conditions and follows a mass-dependent pattern. Spring samples follow a similar pattern to that of rainwater and suggest that spring water originates directly from rainfall. These findings further support the hypothesis of NGT seasonality. However, while the atmospheric composition of noble gases points to direct supply from rainfall to spring aquifer systems, a direct connection between spring water and deeper aquifer levels or the mantle is apparent from He isotopic ratios which display an almost pure He mantle component in some springs.

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

    SciTech Connect

    Allendorf, Mark D.; 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. Cryogenic method for measuring nuclides and fission gases

    DOEpatents

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

    1980-05-02

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

  5. Widespread distribution of ascending fluids transporting mantle helium in the fore-arc region and their upwelling processes: Noble gas and major element composition of deep groundwater in the Kii Peninsula, southwest Japan

    NASA Astrophysics Data System (ADS)

    Morikawa, Noritoshi; Kazahaya, Kohei; Takahashi, Masaaki; Inamura, Akihiko; Takahashi, Hiroshi A.; Yasuhara, Masaya; Ohwada, Michiko; Sato, Tsutomu; Nakama, Atsuko; Handa, Hiroko; Sumino, Hirochika; Nagao, Keisuke

    2016-06-01

    Chemical and isotopic studies including analyses of noble gases were comprehensively conducted on the groundwater of the entire Kii Peninsula, which is located in the fore-arc region of southwest Japan. Groundwater of Na-Cl-HCO3, Na-HCO3-Cl, and Na-Cl types was shown to be distributed across the whole area. Groundwater in the inland central part of the peninsula shows relatively low salinity, whereas groundwater from the area along the ENE-trending Median Tectonic Line (MTL), on the north side of the peninsula, shows high salinity (up to 18,800 mg/L of Cl-) and the presence of unusual heavy oxygen isotopes. This trend is similar to that documented in saline waters from the Arima region (the so-called "Arima-type thermal water"). High 3He/4He ratios relative to the atmospheric value (up to 6.7 Ra) were recorded throughout the Kii Peninsula, covering a wider area than documented previously. The saline groundwater is also strongly depleted in 20Ne and heavy noble gases. From the wide distribution of high 3He/4He values and the associated 20Ne and Cl- concentrations, we infer that aqueous fluids derived from dehydration of the subducting slab are present at depth beneath almost the entire Kii Peninsula. These aqueous fluids may ascend along the major north-dipping boundary faults. The isotopic composition of groundwater from the southern part of the peninsula suggests that the contribution from these dehydration-derived fluids is relatively small in this region. However, volatile components (e.g., noble gases and CO2) in the groundwater of this area may originate from the dehydration-derived fluids. Upwelling of Arima-type thermal water of the Na-Cl-HCO3 type is expected to undergo a phase separation of volatile species due to decompression as the fluid ascends. The variety of water types documented may be due to this water-gas separation and the subsequent incorporation of gaseous species into shallow meteoric groundwater. The observed high 3He/4He ratios in the absence of a mantle wedge below the southern part of the Kii Peninsula may reflect the oblique ascent of these fluids along north-dipping boundary faults.

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  7. Noble Gas Thermometry and Hydrologic Ages: Evidence for Late Holocene Warming in Southwest Texas

    NASA Astrophysics Data System (ADS)

    Castro, M.; Goblet, P.

    2003-12-01

    Paleoclimatic reconstruction through the use of noble gases dissolved in groundwater has been the object of numerous studies in recent years. Unlike many other continental temperature proxies, noble gases have the advantage of providing direct information on atmospheric temperatures at the time rainwater penetrated the ground and joined a particular groundwater reservoir. In recent years, new methods for determination of noble gas temperatures have been developed, which provide a high level of accuracy on such temperature estimations. The issue of paleoclimatic reconstruction through noble gases however, is not only one of accurate temperature determination, but also one of accurate water age estimation so that a correct correspondence between noble gas temperatures and groundwater age can be established and proper paleoclimatic reconstruction attempted. The typical approach to estimate groundwater ages has been based on computing water travel times along streamlines from the recharge to the observation point taking into account only advection. This approach is limited because, like any other tracer, the movement of water in porous media is also affected by cinematic dispersion and molecular diffusion. We have therefore undertaken the formulation of hydrologic models that yield significantly better constraints on groundwater ages in the Carrizo aquifer and surrounding formations of south Texas, where noble gas temperatures have already been determined. To account for groundwater mixing we treat age as one would treat a solute concentration. In order to simulate groundwater ages we used a finite element model of groundwater flow that has been validated by 4He and 3He. The finite model spans a 120.6 Km cross-section between altitudes of +220m and -2210 m, and comprises 58,968 elements and 31,949 nodes. Combination of these newly calculated water ages and previously reported noble gas temperatures reveals new aspects of late Pleistocene and Holocene climate in southwestern Texas, in particular, an abrupt late Holocene temperature increase previously unidentified through 14C dating. Temperature increased by up to 3.4° C in the first half of the last millennium and by 1.5° C between ˜5.6 and 3.7 kyrs BP. More important than the resolution of individual paleoclimate episodes is the identification of a slow cooling trend between ˜1,200 kyrs and ˜200 kyrs, a trend that accelerates during the late Pleistocene and early Holocene. This cooling trend gives way to an extremely rapid increase in temperature in the late Holocene. Such abrupt warming seems to have accelerated in the last millennium and seems to continue at present. This temperature increase is the most striking feature arising from the determination of new groundwater ages.

  8. Platinum-coated non-noble metal-noble metal core-shell electrocatalysts

    SciTech Connect

    Adzic, Radoslav; Zhang, Junliang; Mo, Yibo; Vukmirovic, Miomir

    2015-04-14

    Core-shell particles encapsulated by a thin film of a catalytically active metal are described. The particles are preferably nanoparticles comprising a non-noble core with a noble metal shell which preferably do not include Pt. The non-noble metal-noble metal core-shell nanoparticles are encapsulated by a catalytically active metal which is preferably Pt. The core-shell nanoparticles are preferably formed by prolonged elevated-temperature annealing of nanoparticle alloys in an inert environment. This causes the noble metal component to surface segregate and form an atomically thin shell. The Pt overlayer is formed by a process involving the underpotential deposition of a monolayer of a non-noble metal followed by immersion in a solution comprising a Pt salt. A thin Pt layer forms via the galvanic displacement of non-noble surface atoms by more noble Pt atoms in the salt. The overall process is a robust and cost-efficient method for forming Pt-coated non-noble metal-noble metal core-shell nanoparticles.

  9. 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.

  10. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver, that... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Noble metal alloy. 872.3060 Section 872.3060...

  11. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver, that... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Noble metal alloy. 872.3060 Section 872.3060...

  12. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver, that... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Noble metal alloy. 872.3060 Section 872.3060...

  13. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver, that... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Noble metal alloy. 872.3060 Section 872.3060...

  14. Recovery and use of fission product noble metals

    SciTech Connect

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

    1980-06-01

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

  15. Incorporation of noble metals into aerogels

    DOEpatents

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

    1998-12-22

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

  16. Incorporation of noble metals into aerogels

    DOEpatents

    Hair, Lucy M.; Sanner, Robert D.; Coronado, Paul R.

    1998-01-01

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

  17. Structural Measurements from Images of Noble Gas Diffusion

    NASA Astrophysics Data System (ADS)

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

    2009-03-01

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

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

    SciTech Connect

    Thompson, Alexander E.; Wolverton, C.

    2011-10-01

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

  19. Physiological response of rats to delivery of helium and xenon: implications for hyperpolarized noble gas imaging

    NASA Technical Reports Server (NTRS)

    Ramirez, M. P.; Sigaloff, K. C.; Kubatina, L. V.; Donahue, M. A.; Venkatesh, A. K.; Albert, M. S.; ALbert, M. S. (Principal Investigator)

    2000-01-01

    The physiological effects of various hyperpolarized helium and xenon MRI-compatible breathing protocols were investigated in 17 Sprague-Dawley rats, by continuous monitoring of blood oxygen saturation, heart rate, EKG, temperature and endotracheal pressure. The protocols included alternating breaths of pure noble gas and oxygen, continuous breaths of pure noble gas, breath-holds of pure noble gas for varying durations, and helium breath-holds preceded by two helium rinses. Alternate-breath protocols up to 128 breaths caused a decrease in oxygen saturation level of less than 5% for either helium or xenon, whereas 16 continuous-breaths caused a 31.5% +/- 2.3% decrease in oxygen saturation for helium and a 30.7% +/- 1. 3% decrease for xenon. Breath-hold protocols up to 25 s did not cause the oxygen saturation to fall below 90% for either of the noble gases. Oxygen saturation values below 90% are considered pathological. At 30 s of breath-hold, the blood oxygen saturation dropped precipitously to 82% +/- 0.6% for helium, and to 76.5% +/- 7. 4% for xenon. Breath-holds longer than 10 s preceded by pre-rinses caused oxygen saturation to drop below 90%. These findings demonstrate the need for standardized noble gas inhalation procedures that have been carefully tested, and for continuous physiological monitoring to ensure the safety of the subject. We find short breath-hold and alternate-breath protocols to be safe procedures for use in hyperpolarized noble gas MRI experiments. Copyright 2000 John Wiley & Sons, Ltd.

  20. Imaging with SiPMs in noble-gas detectors

    NASA Astrophysics Data System (ADS)

    Yahlali, N.; Fernandes, L. M. P.; González, K.; Garcia, A. N. C.; Soriano, A.

    2013-01-01

    Silicon photomultipliers (SiPMs) are photosensors widely used for imaging in a variety of high energy and nuclear physics experiments. In noble-gas detectors for double-beta decay and dark matter experiments, SiPMs are attractive photosensors for imaging. However they are insensitive to the VUV scintillation emitted by the noble gases (xenon and argon). This difficulty is overcome in the NEXT experiment by coating the SiPMs with tetraphenyl butadiene (TPB) to convert the VUV light into visible light. TPB requires stringent storage and operational conditions to prevent its degradation by environmental agents. The development of UV sensitive SiPMs is thus of utmost interest for experiments using electroluminescence of noble-gas detectors. It is in particular an important issue for a robust and background free ββ0ν experiment with xenon gas aimed by NEXT. The photon detection efficiency (PDE) of UV-enhanced SiPMs provided by Hamamatsu was determined for light in the range 250-500 nm. The PDE of standard SiPMs of the same model (S10362-33-50C), coated and non-coated with TPB, was also determined for comparison. In the UV range 250-350 nm, the PDE of the standard SiPM is shown to decrease strongly, down to about 3%. The UV-enhanced SiPM without window is shown to have the maximum PDE of 44% at 325 nm and 30% at 250 nm. The PDE of the UV-enhanced SiPM with silicon resin window has a similar trend in the UV range, although it is about 30% lower. The TPB-coated SiPM has shown to have about 6 times higher PDE than the non-coated SiPM in the range 250-315 nm. This is however below the performance of the UV-enhanced prototypes in the same wavelength range. Imaging in noble-gas detectors using UV-enhanced SiPMs is discussed.

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

    PubMed Central

    Anderson, Don L.

    1998-01-01

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

  2. Synthesis of noble metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Bahadory, Mozhgan

    Improved methods were developed for the synthesis of noble metal nanoparticles. Laboratory experiments were designed for introducing of nanotechnology into the undergraduate curriculum. An optimal set of conditions for the synthesis of clear yellow colloidal silver was investigated. Silver nanoparticles were obtained by borohydride reduction of silver nitrate, a method which produces particles with average size of 12+/-2 nm, determined by Transmission Electron Microscopy (TEM). The plasmon absorbance is at 397 nm and the peak width at half maximum (PWHM) is 70-75 nm. The relationship between aggregation and optical properties was determined along with a method to protect the particles using polyvinylpyrrolidone (PVP). A laboratory experiment was designed in which students synthesize yellow colloidal silver, estimate particle size using visible spectroscopy, and study aggregation effects. The synthesis of the less stable copper nanoparticles is more difficult because copper nanopaticles are easily oxidized. Four methods were used for the synthesis of copper nanoparticles, including chemical reduction with sodium borohydride, sodium borohydride with potassium iodide, isopropyl alcohol with cetyltrimethylammonium bormide (CTAB) and reducing sugars. The latter method was also the basis for an undergraduate laboratory experiment. For each reaction, the dependence of stability of the copper nanoparticles on reagent concentrations, additives, relative amounts of reactants, and temperature is explored. Atomic force microscopy (AFM), TEM and UV-Visible Spectroscopy were used to characterize the copper nanoparticles. A laboratory experiment to produce copper nanoparticles from household chemicals was developed.

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

    SciTech Connect

    Cordier, D.; Mousis, O.; Lebonnois, S.; Lavvas, P.; Lobo, L. Q.; Ferreira, A. G. M.

    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.

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

    NASA Astrophysics Data System (ADS)

    Papp, Laszlo; Palcsu, Laszlo; Major, Zoltan

    2010-05-01

    Based on the concentrations of dissolved noble gases in fluid inclusions in speleothems and corals, noble gas temperatures (NGT) might be derived, that would be important climate information [1]. In the case of terrestrial carbonates, it means that the temperature dependency of noble gases in the evolving fluid inclusions is suitable to determine the prevailing temperature. This recognition provides new opportunities for the research of paleoclimate. Additionally, the dissolved noble gases in the fluid inclusions represented in corals could be used to study past sea surface temperatures that are one of the most essential parameter of climate reconstructions. To measure dissolved noble gases in fluid inclusions of a few micro-litres, a noble gas mass spectrometer equipped with an ultra high vacuum preparation line is the most suitable way. The preparation of the carbonate samples is performed in a sample preparation system connected to a static mode VG 5400 noble gas mass spectrometer. As a first step of the sample preparation, one piece of a sample is put into a crusher of the preparation line and then evacuated and heated at night. The crushing of dripstone and coral samples is carried out in a stainless steel pipe with a ferro-magnetic ball at 150 °C temperature, in such a way that the ball is kept on elevating and falling down onto the carbonate sample one hundred times. The aim of the heating is to avoid the water released from the fluid inclusions not to be adsorbed on the surface of the freshly broken carbonate [2]. The water released from the fluid inclusions is frozen into a cold finger, being held at temperature of -70 °C for 15 minutes. In this case, the collection efficiency is better than 99.7 %. Then the cold finger is warmed to 27 °C, and the pressure of the water vapour expanded to the volume of the cold finger is determined by a pressure gauge, which accuracy is better than 0.2 % in the pressure range of 10-2 mbar to 11 mbar. The water vapour pressure range has been calibrated by measuring ten well known water aliquots between 0.45 mg and 3.14 mg sealed in glass capillaries. With this method, the quantity of the water can be determined better than 1% uncertainty. After the dissolved noble gases has been released from the fluid inclusions, they are collected and separated from each other by a cryo system which consists of a stainless steel empty trap and a trap filled with charcoal. The argon, krypton, xenon fraction and the other chemically active gases (N2, O2, CO2, etc.) are trapped in the stainless steel trap at 25 K, while the isotopes of helium and neon in the charcoal trap held at 10 K. So far, the abundance of helium is not measured, because helium does not play a role in the NGT determination due to radiogenic helium component. The helium is pumped away. The neon is released from the stainless steel trap at temperature of 90 K and admitted to the noble gas mass spectrometer. The ion source is tuned for the best sensitivity for neon. The neon isotopes are detected by an electron multiplier in ion counting mode. The argon, krypton and xenon isotopes are measured simultaneously. The gases are released from the stainless steel trap at 150 K, and introduced into a getter trap in order to be purified from the other non-inert gases. Then the pure argon, krypton, xenon fraction is admitted to the mass spectrometer. The isotopes of argon are detected by a Faraday cup, while krypton and xenon isotopes are detected by an electron multiplier. After every single mass spectrometric measurement fast calibration are executed. The calibration of the mass spectrometric measurement is performed by means of well known air aliquots taken from an air reservoir in which the pressure is 2.0052 Pa. The results of the calibration measurements show that the reproducibility is about 2% for all noble gas isotopes measured. This error in noble gas concentrations results in an uncertainty of about 1 °C or lower in the determination of NGT, if the amount of the excess air is smaller than 10 V/V %. To check the overall precision of our measurements, standard water samples of a few micro-litres have been prepared. Air equilibrated water has been closed in copper capillaries. The measurements reflected the same precision obtained in the measurements of air calibrations. [1] Kluge T., Marx T., Scholz D., Niggemann S., Mangini A., Aeschbach-Hertig W., 2008. A new tool for palaeoclimate reconstruction: Noble gas temperatures from fluid inclusions in speleothems. Earth and Planetary Science Letters 269, 408-415. [2] Dennis P.F., Rowe P.J., Atkinson T.C., 2001. Geochimica et Cosmochimica Acta 65, 871-884.

  5. 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.

  6. The UKB prescription and the heavy atom effects on the nuclear magnetic shielding of vicinal heavy atoms.

    PubMed

    Maldonado, Alejandro F; Aucar, Gustavo A

    2009-07-21

    Fully relativistic calculations of NMR magnetic shielding on XYH3 (X = C, Si, Ge and Sn; Y = Br, I), XHn (n = 1-4) molecular systems and noble gases performed with a fully relativistic polarization propagator formalism at the RPA level of approach are presented. The rate of convergence (size of basis set and time involved) for calculations with both kinetic balance prescriptions, RKB and UKB, were investigated. Calculations with UKB makes it feasible to obtain reliable results for two or more heavy-atom-containing molecules. For such XYH3 systems, the influence of heavy vicinal halogen atoms on sigma(X) is such that heavy atom effects on heavy atoms (vicinal plus their own effects or HAVHA + HAHA effects) amount to 30.50% for X = Sn and Y = I; being the HAHA effect of the order of 25%. So the vicinal effect alone is of the order of 5.5%. The vicinal heavy atom effect on light atoms (HALA effect) is of the order of 28% for X = C and Y = I. A similar behaviour, but of opposite sign, is observed for sigma(Y) for which sigmaR-NR (I; X = C) (HAHA effect) is around 27% and sigmaR-NR(I; X = Sn) (HAVHA + HAHA effects) is close to 21%. Its electronic origin is paramagnetic for halogen atoms but both dia- and paramagnetic for central atoms. The effect on two bond distant hydrogen atoms is such that the largest variation of sigma(H) within the same family of XYH3 molecules appears for X = Si and Y = I: around 20%. In this case sigma(H; X = Sn, Y = I) = 33.45 ppm and sigma(H; X = Sn, Y = H) = 27.82 ppm. PMID:19842479

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1984-09-01

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

  9. 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.

  10. Noble Metal Nanoparticles for Biosensing Applications

    PubMed Central

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

    2012-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

  12. Photoionization of the outer electrons in noble gas endohedral atoms

    SciTech Connect

    Amusia, M. Ya. Baltenkov, A. S.; Chernysheva, L. V.

    2008-08-15

    We suggest a prominent modification of the outer shell photoionization cross section in noble gas (NG) endohedral atoms NG-C{sub n} under the action of the electron shell of fullerene C{sub n}. This shell leads to two important effects: a strong enhancement of the cross section due to fullerene shell polarization under the action of the incoming electromagnetic wave and to prominent oscillation of this cross section due to the reflection of a photoelectron from the NG by the fullerene shell. Both factors lead to powerful maxima in the outer shell ionization cross sections of NG-C{sub n}, which we call giant endohedral resonances. The oscillator strength reaches a very large value in the atomic scale, 25. We consider atoms of all noble gases except He. The polarization of the fullerene shell is expressed in terms of the total photoabsorption cross section of the fullerene. The photoelectron reflection is taken into account in the framework of the so-called bubble potential, which is a spherical {delta}-type potential. It is assumed in the derivations that the NG is centrally located in the fullerene. It is also assumed, in accordance with the existing experimental data, that the fullerene radius R{sub C} is much larger than the atomic radius r{sub A} and the thickness {delta}{sub C} of the fullerene shell. As was demonstrated recently, these assumptions allow us to represent the NG-C{sub n} photoionization cross section as a product of the NG cross section and two well-defined calculated factors.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  14. 21 CFR 872.3060 - Noble metal alloy.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Noble metal alloy. 872.3060 Section 872.3060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily...

  15. 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.

  16. 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)

  17. 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

  18. Bamboo Pointer belonging to Levi F. Noble

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

  19. MICROWAVE-ASSISTED SYNTHESIS OF NOBLE NANOSTRUCTURES

    EPA Science Inventory

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

  20. CONTROL ROD ALLOY CONTAINING NOBLE METAL ADDITIONS

    DOEpatents

    Anderson, W.K.; Ray, W.E.

    1960-05-01

    Silver-base alloys suitable for use in the fabrication of control rods for neutronic reactors are given. The alloy consists of from 0.5 wt.% to about 1.5 wt.% of a noble metal of platinum, ruthenium, rhodium, osmium, or palladium, up to 10 wt.% of cadmium, from 2 to 20 wt.% indium, the balance being silver.

  1. 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…

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

    DOEpatents

    Ricco, Antonio J.; Manginell, Ronald P.; Huber, Robert J.

    1998-01-01

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

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

    ScienceCinema

    Shutt, Tom [Case Western Reserve, Cleveland, Ohio, United States

    2009-09-01

    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.

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

    DOEpatents

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

    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.

  5. Electron-beam generation in a wide-aperture open gas discharge: A comparative study for different inert gases

    SciTech Connect

    Bokhan, P. A.; Zakrevsky, Dm. E.

    2010-08-30

    In the present study, electron-beam generation by open discharges was examined. The study was performed at gas pressures up to 20 Torr, and covered all inert gases. At voltages up to 8 kV, electron-beam currents up to 1600 A with current density {approx}130 A/cm{sup 2} and a beam generation efficiency in excess of 93% were obtained. The production of electrons from cold cathode was concluded to be of photoemissive nature, enabling the production of high-intensity electron beams in any noble gas or in a mixture of a noble gas with molecular gases irrespective of cathode material.

  6. Separation of polar gases from nonpolar gases

    DOEpatents

    Kulprathipanja, Santi

    1986-01-01

    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.

  7. Separation of polar gases from nonpolar gases

    DOEpatents

    Kulprathipanja, S.; Kulkarni, S.S.

    1986-08-26

    Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and 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 use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

  8. Separation of polar gases from nonpolar gases

    DOEpatents

    Kulprathipanja, Santi; Kulkarni, Sudhir S.

    1986-01-01

    Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and 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 use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

  9. 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.

  10. 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.

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

    NASA Technical Reports Server (NTRS)

    Bulzan, D. L.

    1982-01-01

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

  12. 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

  13. EXTERNAL PHOTOEVAPORATION OF THE SOLAR NEBULA: JUPITER's NOBLE GAS ENRICHMENTS

    SciTech Connect

    Monga, Nikhil; Desch, Steven

    2015-01-01

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

  14. Applications of Noble Gas Radiation Detectors to Counter-terrorism

    NASA Astrophysics Data System (ADS)

    Vanier, Peter E.; Forman, Leon

    2002-10-01

    Radiation detectors are essential tools in the detection, analysis and disposition of potential terrorist devices containing hazardous radioactive and/or fissionable materials. For applications where stand-off distance and source shielding are limiting factors, large detectors have advantages over small ones. The ability to distinguish between Special Nuclear Materials and false-positive signals from natural or man-made benign sources is also important. Ionization chambers containing compressed noble gases, notably xenon and helium-3, can be scaled up to very large sizes, improving the solid angle for acceptance of radiation from a distant source. Gamma spectrometers using Xe have a factor of three better energy resolution than NaI scintillators, allowing better discrimination between radioisotopes. Xenon detectors can be constructed so as to have extremely low leakage currents, enabling them to operate for long periods of time on batteries or solar cells. They are not sensitive to fluctuations in ambient temperature, and are therefore suitable for deployment in outdoor locations. Position-sensitive 3He chambers have been built as large as 3000 cm2, and with spatial resolution of less than 1 mm. Combined with coded apertures made of cadmium, they can be used to create images of thermal neutron sources. The natural background of spallation neutrons from cosmic rays generates a very low count rate, so this instrument could be quite effective at identifying a man-made source, such as a spontaneous fission source (Pu) in contact with a moderator (high explosive).

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

    NASA Astrophysics Data System (ADS)

    Monga, Nikhil; Desch, Steven

    2015-01-01

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

  16. Noble Metals Would Prevent Hydrogen Embrittlement

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  19. Engineering noble metal nanomaterials for environmental applications

    NASA Astrophysics Data System (ADS)

    Li, Jingguo; Zhao, Tingting; Chen, Tiankai; Liu, Yanbiao; Ong, Choon Nam; Xie, Jianping

    2015-04-01

    Besides being valuable assets in our daily lives, noble metals (namely, gold, silver, and platinum) also feature many intriguing physical and chemical properties when their sizes are reduced to the nano- or even subnano-scale; such assets may significantly increase the values of the noble metals as functional materials for tackling important societal issues related to human health and the environment. Among which, designing/engineering of noble metal nanomaterials (NMNs) to address challenging issues in the environment has attracted recent interest in the community. In general, the use of NMNs for environmental applications is highly dependent on the physical and chemical properties of NMNs. Such properties can be readily controlled by tailoring the attributes of NMNs, including their size, shape, composition, and surface. In this feature article, we discuss recent progress in the rational design and engineering of NMNs with particular focus on their applications in the field of environmental sensing and catalysis. The development of functional NMNs for environmental applications is highly interdisciplinary, which requires concerted efforts from the communities of materials science, chemistry, engineering, and environmental science.

  20. Engineering noble metal nanomaterials for environmental applications.

    PubMed

    Li, Jingguo; Zhao, Tingting; Chen, Tiankai; Liu, Yanbiao; Ong, Choon Nam; Xie, Jianping

    2015-05-01

    Besides being valuable assets in our daily lives, noble metals (namely, gold, silver, and platinum) also feature many intriguing physical and chemical properties when their sizes are reduced to the nano- or even subnano-scale; such assets may significantly increase the values of the noble metals as functional materials for tackling important societal issues related to human health and the environment. Among which, designing/engineering of noble metal nanomaterials (NMNs) to address challenging issues in the environment has attracted recent interest in the community. In general, the use of NMNs for environmental applications is highly dependent on the physical and chemical properties of NMNs. Such properties can be readily controlled by tailoring the attributes of NMNs, including their size, shape, composition, and surface. In this feature article, we discuss recent progress in the rational design and engineering of NMNs with particular focus on their applications in the field of environmental sensing and catalysis. The development of functional NMNs for environmental applications is highly interdisciplinary, which requires concerted efforts from the communities of materials science, chemistry, engineering, and environmental science. PMID:25866322

  1. Using noble gas ratios to determine the origin of ground ice

    NASA Astrophysics Data System (ADS)

    Utting, Nicholas; Lauriol, Bernard; Lacelle, Denis; Clark, Ian

    2016-01-01

    Argon, krypton and xenon have different solubilities in water, meaning their ratios in water are different from those in atmospheric air. This characteristic is used in a novel method to distinguish between ice bodies which originate from the compaction of snow (i.e. buried snow banks, glacial ice) vs. ice which forms from the freezing of groundwater (i.e. pingo ice). Ice which forms from the compaction of snow has gas ratios similar to atmospheric air, while ice which forms from the freezing of liquid water is expected to have gas ratios similar to air-equilibrated water. This analysis has been conducted using a spike dilution noble gas line with gas extraction conducted on-line. Samples were mixed with an aliquot of rare noble gases while being melted, then extracted gases are purified and cryogenically separated. Samples have been analysed from glacial ice, buried snow bank ice, intrusive ice, wedge ice, cave ice and two unknown ice bodies. Ice bodies which have formed from different processes have different gas ratios relative to their formation processes.

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

    SciTech Connect

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

    1998-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

    A generally accepted basic principle in relation to the use of the noble gas thermometer in groundwater flow systems is that high-frequency noble gas climatic signals are lost due to the effect of dispersion. This loss of signal, combined with 14C dating issues, makes it only suited to identify major climatic events such as the Last Glacial Maximum (LGM). Consequently, the identification of significant noble gas temperature (NGT) cooling (≥ 5 °C) with respect to present time has systematically been associated with the occurrence of the LGM even when reasonable water age controls were unavailable. It has also become apparent at a number of studied sites that modern NGTs estimated through standard models [M. Stute, P. Schlosser, Principles and applications of the noble gas paleothermometer, in: P.K. Swart, K.C. Lohmann, J.A. McKenzie, S. Savin, (Eds), Climate change in continental isotopic records, Geophysical monograph 78, AGU (1993) 89-100.; W. Aeschbach-Hertig, F. Peeters, U. Beyerle, R. Kipfer, Paleotemperature reconstruction from noble gases in ground water taking into account equilibration with entrapped air, Nature 405(6790) (2000) 1040-1044.] are unable to reproduce ground temperatures at the interface with the unsaturated zone, a basic requirement for proper paleoclimate reconstruction through noble gases. Instead, a systematic bias to low NGTs in recharge areas is observed. The Carrizo aquifer, in which the LGM was previously identified [M. Stute, P. Schlosser, J.F. Clark, W.S. Broecker, Paleotemperatures in the Southwestern United States derived from noble gases in ground water, Science 256(5059) (1992) 1000-1001.] and which presents an NGT bias of over 4 °C, is an ideal setting to analyze and revise basic principles and assumptions in relation with the use of the noble gas thermometer. Here, we present a new noble gas data set (49 measurements) collected at 20 different locations in the Carrizo aquifer. This new data set together with previously published data (20 measurements) was used to calibrate a 3-D groundwater flow and 4He transport model in which simulations of groundwater age were subsequently carried out. These account for mixing processes due to advection, dispersion, diffusion, and cross-formational flow. We first show that samples previously attributed to the LGM belong in fact to the middle Holocene. Through a step-by-step approach we then proceed to carry out a comparative analysis of both the impact of dispersion on high frequency climatic signals and assumptions underlying competing NGT models. Our combined analysis indicates that groundwater flow systems, at least those with similar characteristics to that of the Carrizo, do have the ability to preserve short term (100-200 yrs) climatic fluctuations archived by noble gases. It also shows that abrupt climate shifts during the mid-late Holocene which are associated with significant NGT changes (≥ 5 °C) do not reflect equally important changes in the mean annual atmospheric temperature (MAAT). Instead, these reflect the combined effect of atmospheric temperature changes, seasonality of recharge and, above all, significant variations of the water table depth which result from shifts between humid and arid regimes. Together with NGTs, our excess air record plays a critical role in identifying such abrupt climate changes. Specifically, the Carrizo combined data set indicates an abrupt shift from a cool, humid regime to a warmer, arid one at ˜ 1 kyrs BP. A major Holocene (˜ 6 kyrs BP) NGT change of 7.7 °C with respect to present now identified is mostly the result of a dramatic water table drop which occurred during the ˜ 1 kyrs BP transition period. Current NGTs in the Carrizo recharge area do not appear to be recording atmospheric changes. Rather, these are recording ground conditions reflecting mostly the impact of heat flow in the area. We also show that observed systematic offsets in NGT recharge areas can be reconciled through NGT estimation models which account for a noble gas partial pressure increase in the unsaturated zone, potentially due to O 2 depletion.

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

    NASA Technical Reports Server (NTRS)

    Burgess, Raymond; Turner, Grenville

    1994-01-01

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

  5. Dissolved Gases as Indicators for Stream-Ground Water Interactions

    NASA Astrophysics Data System (ADS)

    Werner, S. F.; Browne, B. A.; Wallschlaeger, C. W.; Wyss, J. R.; Bowling, J. M.

    2007-12-01

    The connection between groundwater and surface water varies along stream corridors, but these hydrologic changes are typically difficult to observe or measure. Many dissolved gases entering streams via groundwater discharge are either undersaturated or supersaturated with respect to atmospheric equilibrium due to physical or biological mechanisms. Because such gases behave non-conservatively (e.g., via losses to the atmosphere) within the stream channel, their longitudinal patterns can potentially help identify where groundwater enters or exits a stream system. Such information can be very useful for understanding stream water quality and the impacts of land management. Unfortunately, dissolved gases (other than oxygen) have not been frequently employed in studies of stream systems, and their full potential as hydrologic tools has not been established. A better understanding of how dissolved gases can be used to study the groundwater/surface water connection is needed. In this study we present and interpret longitudinal patterns of several gases along an 8 km stretch of a baseflow dominated stream located in a predominantly agricultural sand plain watershed of central Wisconsin. Dissolved gas measurements included oxygen, carbon dioxide, methane, nitrous oxide, chlorofluorocarbons, and noble gases. Major and minor ions were also measured. Sampling locations were sited at 350-m intervals along the thalweg of the stream into headwater tributaries. Losing stream sections had CFCs, nitrous oxide, and methane concentrations near atmospheric equilibrium. Gaining stream sections were supersaturated with nitrous oxide, methane, and carbon dioxide and undersaturated with CFCs and oxygen. High concentrations of nitrous oxide accompanied nitrate entering the stream.

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

    NASA Astrophysics Data System (ADS)

    Carrigan, Charles R.; Sun, Yunwei

    2014-03-01

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

  7. Subduction-related metasomatism recorded as noble gas compositions in the Finero Phlogopite-Peridotites, Italian Western Alps

    NASA Astrophysics Data System (ADS)

    Matsumoto, T.; Morishita, T.; Matsuda, J.; Fujioka, T.; Takebe, M.; Yamamoto, K.; Arai, S.

    2002-12-01

    It has been demonstrated that noble gases trapped in fluid inclusions of ultramafic xenoliths are quite useful tracers of metasomatic events in the lithospheric mantle. Some recent study on noble gases in Horoman ultramafic complex, Hokkaido, Japan, revealed that the orogenic peridotites can also be a suitable target for noble gas study and that they contain a homogeneous mixture of mantle-He and air-Ar, suggesting a possible recycling and preservation of heavier noble gases of surface reservoirs in the deeper mantle domains (Matsumoto et al., 2001). Here we report results of our new investigation on noble gases in a unique specimen having thin layer of very fine-grained apatite and opx in the fresh phlogopite lherzolite from Finero ultramafic complex, Italian Western Alps. We have also examined fresh olivine grains separated from a phlogopite-lherzolite without such apatite-layer. The fluid inclusions of this olivine separates appeared to be very rich in radiogneic component such as 4He, 21Ne and 40Ar, suggesting the derivation of fluids from a crust-like reservoir. Such a crustal component appeared to be also contained in the samples with the apatite-opx layer, but we need to have an additional isotopically distinct component to explain progressive increase in 3He concentration and decrease in 40Ar/36Ar ratios observed towards the apatite-rich layer. High 3He contents and low 40Ar/36Ar ratios are consistent with the signature expected for the slab-derived metasomatic fluid as was observed in Horoman ultramafic complex. There is a clear mixing trend defined in a 3He/36Ar versus 40Ar/36Ar diagram with the crustal and slab-derived fluids as endmember compositions, suggesting that the complex had metsomatised by fluids derived from geochemically distinct regions at distinct geotectonic settings. The parental melt or fluids responsible for the formation of the apatite-rich layer should be derived from the slab-derived component, which is consistent with a notion that the Finero mantle was once in the mantle wedge.

  8. Noble gas adsorption with and without mechanical stress: Not Martian signatures but fractionated air

    NASA Astrophysics Data System (ADS)

    Schwenzer, Susanne P.; Herrmann, Siegfried; Ott, Ulrich

    2012-06-01

    Sample preparation, involving physical and chemical methods, is an unavoidable step in geochemical analysis. From a noble gas perspective, the two important effects are loss of sample gas and/or incorporation of air, which are significant sources of analytical artifacts. This article reports on the effects of sample exposure to laboratory air without mechanical influence and during sample grinding. The experiments include pure adsorption on terrestrial analog materials (gibbsite and olivine) and grinding of Martian meteorites. A consistent observation is the presence of an elementally fractionated air component in the samples studied. This is a critical form of terrestrial contamination in meteorites as it often mimics the heavy noble gas signatures of known extra-terrestrial end-members that are the basis of important conclusions about the origin and evolution of a meteorite. Although the effects of such contamination can be minimized by avoiding elaborate sample preparation protocols, caution should be exercised in interpreting the elemental ratios (Ar/Xe, Kr/Xe), especially in the low-temperature step extractions. The experiments can also be transferred to the investigation of Martian meteorites with long terrestrial residence times, and to Mars, where the Mars Science Laboratory mission will be able to measure noble gas signatures in the current atmosphere and in rocks and soils collected on the surface in Gale crater.

  9. Trends in source gases

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  10. New applications of noble metal catalysts in hydrocracking

    SciTech Connect

    Mitchell, D.H.G.; Bertram, R.V.; Dencker, G.D.

    1995-09-01

    The paper explores how a noble metal hydrocracking catalyst functions stably in a hydrogen sulfide and ammonia environment and, in particular, how the physical positioning of the noble metal molecules affects catalyst performance. A commercial example, HC-28 catalyst in the Unicracking unit at Marathon Oil Refinery in Robinson, Illinois, demonstrates the success of the noble metal catalyst approach for naphtha production. In addition, a new Unicracking catalyst, HC-35, which uses a noble metal component to produce high-quality middle distillates, is introduced. The paper also shows how refiners may derive increased economic and operational benefits from their catalyst investment by using the latest developments in reactor internals design.

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

    DOEpatents

    Ray, Siba P.; Woods, Robert W.; Dawless, Robert K.; Hosler, Robert B.

    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.

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

    DOEpatents

    Ray, Siba P.; Woods, Robert W.; Dawless, Robert K.; Hosler, Robert B.

    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.

  13. 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.

  14. Transport of Trace Gases

    NASA Technical Reports Server (NTRS)

    Schoeberl, Mark R.

    2005-01-01

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

  15. Noble gas storage and delivery system for ion propulsion

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  16. 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

  17. Photoelectron spectrometer for attosecond spectroscopy of liquids and gases.

    PubMed

    Jordan, I; Huppert, M; Brown, M A; van Bokhoven, J A; Wörner, H J

    2015-12-01

    A new apparatus for attosecond time-resolved photoelectron spectroscopy of liquids and gases is described. It combines a liquid microjet source with a magnetic-bottle photoelectron spectrometer and an actively stabilized attosecond beamline. The photoelectron spectrometer permits venting and pumping of the interaction chamber without affecting the low pressure in the flight tube. This pressure separation has been realized through a sliding skimmer plate, which effectively seals the flight tube in its closed position and functions as a differential pumping stage in its open position. A high-harmonic photon spectrometer, attached to the photoelectron spectrometer, exit port is used to acquire photon spectra for calibration purposes. Attosecond pulse trains have been used to record photoelectron spectra of noble gases, water in the gas and liquid states as well as solvated species. RABBIT scans demonstrate the attosecond resolution of this setup. PMID:26724045

  18. Photoelectron spectrometer for attosecond spectroscopy of liquids and gases

    NASA Astrophysics Data System (ADS)

    Jordan, I.; Huppert, M.; Brown, M. A.; van Bokhoven, J. A.; Wörner, H. J.

    2015-12-01

    A new apparatus for attosecond time-resolved photoelectron spectroscopy of liquids and gases is described. It combines a liquid microjet source with a magnetic-bottle photoelectron spectrometer and an actively stabilized attosecond beamline. The photoelectron spectrometer permits venting and pumping of the interaction chamber without affecting the low pressure in the flight tube. This pressure separation has been realized through a sliding skimmer plate, which effectively seals the flight tube in its closed position and functions as a differential pumping stage in its open position. A high-harmonic photon spectrometer, attached to the photoelectron spectrometer, exit port is used to acquire photon spectra for calibration purposes. Attosecond pulse trains have been used to record photoelectron spectra of noble gases, water in the gas and liquid states as well as solvated species. RABBIT scans demonstrate the attosecond resolution of this setup.

  19. Photoelectron spectrometer for attosecond spectroscopy of liquids and gases

    SciTech Connect

    Jordan, I.; Huppert, M.; Wörner, H. J.; Brown, M. A.; Bokhoven, J. A. van

    2015-12-15

    A new apparatus for attosecond time-resolved photoelectron spectroscopy of liquids and gases is described. It combines a liquid microjet source with a magnetic-bottle photoelectron spectrometer and an actively stabilized attosecond beamline. The photoelectron spectrometer permits venting and pumping of the interaction chamber without affecting the low pressure in the flight tube. This pressure separation has been realized through a sliding skimmer plate, which effectively seals the flight tube in its closed position and functions as a differential pumping stage in its open position. A high-harmonic photon spectrometer, attached to the photoelectron spectrometer, exit port is used to acquire photon spectra for calibration purposes. Attosecond pulse trains have been used to record photoelectron spectra of noble gases, water in the gas and liquid states as well as solvated species. RABBIT scans demonstrate the attosecond resolution of this setup.

  20. A generic biokinetic model for noble gases with application to radon

    SciTech Connect

    Leggett, Richard Wayne; Marsh, James; Gregoratto, Demetrio; Blanchardon, Eric

    2013-01-01

    The International Commission for Radiological Protection (ICRP) currently uses a dose conversion coefficient to calculate effective dose per unit exposure to radon and its progeny. The coefficient is derived by dividing the detriment associated with unit exposure to radon, as estimated from epidemiological studies, by the detriment per unit effective dose, as estimated mainly from atomic bomb survivor data and animal studies. In a recent statement the ICRP indicated that future guidance on exposure to radon and its progeny will be developed in the same way as guidance for any other radionuclide. That is, intake of radon and progeny will be limited on the basis of effective dose coefficients derived from biokinetic and dosimetric models. This paper proposes a biokinetic model for systemic (absorbed) radon for use in the calculation of dose coefficients for inhaled or ingested radon. The model is based largely on physical laws governing transfer of a non-reactive and soluble gas between materials. Model predictions are shown to be consistent with results of controlled studies of the fate of internally deposited radon in human subjects.

  1. 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.

  2. Total scattering cross sections and interatomic potentials for neutral hydrogen and helium on some noble gases

    SciTech Connect

    Ruzic, D.N.; Cohen, S.A.

    1985-04-01

    Measurements of energy-dependent scattering cross sections for 30 to 1800 eV D incident on He, Ne, Ar, and Kr, and for 40 to 850 eV He incident on He, Ar, and Kr are presented. They are determined by using the charge-exchange efflux from the Princeton Large Torus tokamak as a source of D or He. These neutrals are passed through a gas-filled scattering cell and detected by a time-of-flight spectrometer. The cross section for scattering greater than the effective angle of the apparatus (approx. =20 mrad) is found by measuring the energy-dependent attenuation of D or He as a function of pressure in the scattering cell. The interatomic potential is extracted from the data.

  3. Thermodynamic Functions of Solvation of Hydrocarbons, Noble Gases, and Hard Spheres in Tetrahydrofuran-Water Mixtures.

    PubMed

    Sedov, I A; Magsumov, T I

    2015-07-16

    Thermodynamic solvation properties of mixtures of water with tetrahydrofuran at 298 K are studied. The Gibbs free energies and enthalpies of solvation of n-octane and toluene are determined experimentally. For molecular dynamics simulations of the binary solvent, we have modified a TraPPE-UA model for tetrahydrofuran and combined it with the SPC/E potential for water. The excess thermodynamic functions of neon, xenon, and hard spheres with two different radii are calculated using the particle insertion method. Simulated and real systems share the same characteristic trends for the thermodynamic functions. A maximum is present on dependencies of the enthalpy of solvation from the composition of solvent at 70-90 mol % water, making it higher than in both of the cosolvents. It is caused by a high enthalpy of cavity formation in the mixtures rich with water due to solvent reorganization around the cavity, which is shown by calculation of the enthalpy of solvation of hard spheres. Addition of relatively small amounts of tetrahydrofuran to water effectively suppresses the hydrophobic effect, leading to a quick increase of both the entropy and enthalpy of cavity formation and solvation of low polar molecules. PMID:26115405

  4. Noble gases in individual L chondritic micrometeorites preserved in an Ordovician limestone

    NASA Astrophysics Data System (ADS)

    Meier, M. M. M.; Schmitz, B.; Baur, H.; Wieler, R.

    2010-02-01

    We have measured the He and Ne concentrations and isotopic ratios of individual sediment-dispersed extraterrestrial chromite grains (63-180 μm in diameter) from an Ordovician limestone in southern Sweden. In the same sediment, many fossil meteorites were found and have been attributed to the L chondrite parent body breakup event ˜ 470 Ma ago. In this analysis of 37 individual extraterrestrial chromite grains of L chondritic major element composition, at least 35 (˜ 95%) contain surface-implanted helium and neon of fractionated solar wind composition, implying that these grains are (relict parts of) fossil micrometeorites of asteroidal origin. Similar to what has been observed in recent micrometeorites collected in the polar regions, significant amounts of cosmogenic 21Ne were found in several grains, resulting in cosmic ray exposure (CRE) ages of up to ˜ 77 Myr. These ages exceed both dynamical lifetimes for asteroidal micrometeorites of this size as well as CRE ages observed in chromites from fossil meteorites from the same sediment beds. Significant contributions from terrestrial sources, like nucleogenic and cosmic-ray muon induced 21Ne can be excluded in the extraterrestrial chromites, since 11 terrestrial chrome spinel grains from the same sediment beds did not contain any measurable 21Ne excesses. Having found micrometeorites of undisputed asteroidal origin with cosmic ray exposure ages of several 10 7 years implies that high cosmic ray exposure ages alone are not a good indicator of cometary origin, in opposition to what has been suggested for recent micrometeorites and IDPs. We propose instead that these grains collected their cosmogenic 21Ne while residing in the regolith layer of their parent body.

  5. Evidence for multiple magma ocean outgassing and atmospheric loss episodes from mantle noble gases

    NASA Astrophysics Data System (ADS)

    Tucker, Jonathan M.; Mukhopadhyay, Sujoy

    2014-05-01

    The energy associated with giant impacts is large enough to generate global magma oceans during Earth's accretion. However, geochemical evidence requiring a terrestrial magma ocean is scarce. Here we present evidence for at least two separate magma ocean outgassing episodes on Earth based on the ratio of primordial 3He to 22Ne in the present-day mantle. We demonstrate that the depleted mantle 3He/22Ne ratio is at least 10 while a more primitive mantle reservoir has a 3He/22Ne ratio of 2.3 to 3. The 3He/22Ne ratios of the mantle reservoirs are higher than possible sources of terrestrial volatiles, including the solar nebula ratio of 1.5. Therefore, a planetary process must have raised the mantle's 3He/22Ne ratio. We show that long-term plate tectonic cycling is incapable of raising the mantle 3He/22Ne ratio and may even lower it. However, ingassing of a gravitationally accreted nebular atmosphere into a magma ocean on the proto-Earth explains the 3He/22Ne and 20Ne/22Ne ratios of the primitive mantle reservoir. Increasing the mantle 3He/22Ne ratio to a value of 10 in the depleted mantle requires at least two episodes of atmospheric blow-off and magma ocean outgassing associated with giant impacts during subsequent terrestrial accretion. The preservation of a low 3He/22Ne ratio in a primitive reservoir sampled by plumes suggests that the later giant impacts, including the Moon-forming giant impact, did not generate a whole mantle magma ocean. Atmospheric loss episodes associated with giant impacts provide an explanation for Earth's subchondritic C/H, N/H, and Cl/F elemental ratios while preserving chondritic isotopic ratios. If so, a significant proportion of terrestrial water and potentially other major volatiles were accreted prior to the last giant impact, otherwise the fractionated elemental ratios would have been overprinted by the late veneer.

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

    PubMed

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

    2012-09-24

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

  7. Synergetic effect in a mixture of noble gases around the Paschen minimum

    SciTech Connect

    Despotovic, Dejan; Cvetic, Jovan; Stankovic, Koviljka; Osmokrovic, Predrag

    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.

  8. Angular distributions in the double ionization of the noble gases by electron impact

    SciTech Connect

    Dal Cappello, C.; Hda, H.; Roy, A.C.

    1995-05-01

    A fivefold differential cross section for electron-impact double ionization of Ne, Ar, Kr, and Xe is calculated for an incident energy of about 5.5 keV and low momentum transfer. The calculation is based on the first Born approximation. Correlation is taken into account both in the initial state and in the final state. The results obtained are in reasonably good agreement with the available experimental data. Many other typical situations are investigated in order to identify the best choices of the kinematical parameters for future experiments.

  9. Mass fractionation of noble gases in diffusion-limited hydrodynamic hydrogen escape

    NASA Technical Reports Server (NTRS)

    Zahnle, Kevin; Pollack, James B.; Kasting, James F.

    1990-01-01

    The theory of mass fractionation by hydrogen is presently extended to atmospheres in which hydrogen is not the major constituent. This theoretical framework is applied to three different cases. In the first, it is shown that the fractionation of terrestrial atmospheric neon with respect to mantle neon is explainable as a consequence of diffusion-limited hydrogen escape from a steam atmosphere toward the end of the accretion process. In the second, the anomalously high Ar-38/Ar-36 ratio of Mars is shown to be due to hydrodynamic fractionation by a vigorously escaping and very pure hydrogen wind. In the last case, it is speculated that the currently high Martian D/H ratio emerged during the hydrodynamic escape phase which fractionated Ar.

  10. 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.

  11. Carbon and Noble Gases in Sutter"s Mill: Relationship to CM Chondrites

    NASA Astrophysics Data System (ADS)

    Grady, M. M.; Verchovsky, A. B.; Gilmour, I.; Yin, Q.-Z.

    2012-09-01

    Sutter"s Mill fell in California in April 2012. Because of its fresh state, we are interested in the light element history of this meteorite, for comparison with other carbonaceous chondrites, particularly CM chondrites and the unusual Tagish Lake.

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

    NASA Technical Reports Server (NTRS)

    Srinivasan, B.; Anders, E.

    1978-01-01

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

  13. Submicron defects in rapidly solidified Type 304 stainless steel powders containing noble gases

    SciTech Connect

    Bae, J.C.; Kelly, T.F.; Flinn, J.E.; Wright, R.N.

    1988-05-01

    The purpose of this work is to examine the defect microstructure of 304 SS powders processed by different atomization methods. The powders examined were processed by centrifugal atomization (CA) and vacuum gas atomization (VGA). In the CA process the molten droplets exiting from the spinning cup were convectively cooled with flowing helium. The VGA process involves pressurizing and mechanical mixing of the melt with argon. The entrapped argon in the melt, as well as the carrier argon associated with the melt stream, produces the molten droplets. Optical microscopy was performed on screened particle sizes to resolve the morphological features such as porosity and solidification microstructure.

  14. Relation of Electron Scattering Cross-Sections to Drift Measurements in Noble Gases

    NASA Astrophysics Data System (ADS)

    Stacey, Blake

    2005-04-01

    I 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 isotropic scatterers is presented, providing a simplified version of Biagi's MAGBOLTZ algorithm. Using this Monte Carlo software, I examine the thermalization of electron swarms, focusing on their drift velocity and Shannon entropy, providing justification for a set of analytic expressions for drift measurements which are valid in the hydrodynamic regime. These expressions are then used to estimate the scattering cross section, first by a simple grid interpolation and then through a genetic algorithm (GA). This technique demonstrates that the He-4 momentum-transfer cross section in the 0-7 eV range is approximately 6.5 å^2, with a peak near 2 eV, in agreement with literature values.

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

    PubMed

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

    2013-04-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  17. Predicted versus observed cosmic-ray-produced noble gases in lunar samples - Improved Kr production ratios

    NASA Technical Reports Server (NTRS)

    Regnier, S.; Hohenberg, C. M.; Marti, K.; Reedy, R. C.

    1979-01-01

    New sets of cross sections for the production of krypton isotopes from targets of Rb, Sr, Y, and Zr have been constructed primarily on the bases of experimental excitation functions for Kr production from Y. These cross sections were used to calculate galactic-cosmic-ray and solar-proton production rates for Kr isotopes in the moon. The paper reports spallation Kr data obtained from ilmenite separates of rocks 10017 and 10047. Production rates and isotopic ratios for cosmogenic Kr observed in ten well-documented lunar samples and in ilmenite separates and bulk samples from several lunar rocks with long but unknown irradiation histories were compared with predicted rates and ratios. The agreements were generally quite good.

  18. First investigation of noble gases in the Dengli H3,8 chondrite

    NASA Technical Reports Server (NTRS)

    Ivanova, M. A.; Assonov, S. S.; Shukolyukov, Yu. A.

    1993-01-01

    The Dengli (H3,8) meteorite, which weighs 243.5 g, is a find from the Karakum desert. It is a complex microbreccia containing unusual clasts which are more typical for regolithic breccias than for H-chondrites. Based on comparisons of Xe and Kr content and isotopic composition, the Dengli does not differ significantly from other H-chondrites. Its exposure age is 7.6 Ma. That is in agreement with common data for the exposure age (6.2 + 0.2 Ma) of 350 H-chondrites. Dengli's K/Ar age (4.01 Ga) coincides with the same ages of many other H-chondrites. Thus the Dengli is not regolithic breccia, and it probably formed during accretion of its parent body.

  19. Reale Gase, tiefe Temperaturen

    NASA Astrophysics Data System (ADS)

    Heintze, Joachim

    Wir werden uns in diesem Kapitel zunächst mit der van der Waals'schen Zustandsgleichung befassen. In dieser Gleichung wird versucht, die Abweichungen, die reale Gase vom Verhalten idealer Gase zeigen, durch physikalisch motivierte Korrekturterme zu berücksichtigen. Es zeigt sich, dass die van derWaals-Gleichung geeignet ist, nicht nur die Gasphase, sondern auch die Phänomene bei der Verflüssigung von Gasen und den kritischen Punkt zu beschreiben.

  20. 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.

  1. Experimental study of the Cs diode pumped alkali laser operation with different buffer gases

    NASA Astrophysics Data System (ADS)

    Knize, Randall J.; Zhdanov, Boris V.; Rotondaro, Matthew D.; Shaffer, Michael K.

    2016-03-01

    Cs diode pumped alkali laser (DPAL) operation using ethane, methane, and mixtures of these hydrocarbons with the noble gases He and Ar as a buffer gas for spin-orbit relaxation was studied in this work. The best Cs DPAL performance in continuous wave operation with flowing gain medium was achieved using pure methane, pure ethane, or a mixture of ethane (minimum of 200 Torr) and He with a total buffer gas pressure of 300 Torr.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  3. Theoretical study of metal noble-gas positive ions

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.

    1989-01-01

    Theoretical calculations have been performed to determine the spectroscopic constant for the ground and selected low-lying electronic states of the transition-metal noble-gas ions Var(+), FeAr(+), CoAr(+), CuHe(+), CuAr(+), and CuKr(+). Analogous calculations have been performed for the ground states of the alkali noble-gas ions LiAr(+), LiKr(+), NaAr(+), and KAr(+) and the alkaline-earth noble-gas ion MgAr(+) to contrast the difference in binding energies between the simple and transition-metal noble-gas ions. The binding energies increase with increasing polarizability of the noble-gas ions, as expected for a charge-induced dipole bonding mechanism. It is found that the spectroscopic constants of the X 1Sigma(+) states of the alkali noble-gas ions are well described at the self-consistent field level. In contrast, the binding energies of the transition-metal noble-gas ions are substantially increased by electron correlation.

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

    SciTech Connect

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

    1996-11-01

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

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

    NASA Technical Reports Server (NTRS)

    Walsworth, Ronald L.

    2004-01-01

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

  6. 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.

  7. Mineralogy and noble gas isotopes of micrometeorites collected from Antarctic snow

    NASA Astrophysics Data System (ADS)

    Okazaki, Ryuji; Noguchi, Takaaki; Tsujimoto, Shin-ichi; Tobimatsu, Yu; Nakamura, Tomoki; Ebihara, Mitsuru; Itoh, Shoichi; Nagahara, Hiroko; Tachibana, Shogo; Terada, Kentaro; Yabuta, Hikaru

    2015-12-01

    We have investigated seven micrometeorites (MMs) from Antarctic snow collected in 2003 and 2010 by means of electron microscopy, X-ray diffraction, micro-Raman spectroscopy, transmission electron microscopy (TEM) observation, and noble-gas isotope analysis. Isotopic ratios of He and Ne indicate that the noble gases in these MMs are mostly of solar wind (SW). Based on the release patterns of SW 4He, which should reflect the degree of heating during atmospheric entry, the seven MMs were classified into three types including two least heated, three moderately heated, and two severely heated MMs. The heating degrees are well correlated to their mineralogical features determined by TEM observation. One of the least heated MMs is composed of phyllosilicates, whereas the other consists of anhydrous minerals within which solar flare tracks were observed. The two severely heated MMs show clear evidence of atmospheric heating such as partial melt of the uppermost surface layer in one and abundant patches of dendritic magnetite and Si-rich glass within an olivine grain in the other. It is noteworthy that a moderately heated MM composed of a single crystal of olivine has a 3He/4He ratio of 8.44 × 10-4, which is higher than the SW value of 4.64 × 10-4, but does not show a cosmogenic 21Ne signature such as 20Ne/21Ne/22Ne = 12.83/0.0284/1. The isotopic compositions of He and Ne in this sample cannot be explained by mixing of a galactic cosmic ray (GCR)-produced component and SW gases. The high 3He/4He ratio without cosmogenic 21Ne signature likely indicates the presence of a 3He-enriched component derived from solar energetic particles.

  8. 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

  9. Thermal conductivity of graphene nanoribbons in noble gaseous environments

    SciTech Connect

    Zhong, Wei-Rong Xu, Zhi-Cheng; Zheng, Dong-Qin; Ai, Bao-Quan

    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.

  10. Cosmogenic noble gas paleothermometry provides new constraints on LGM temperature estimates inferred from glacier extents in the Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Tremblay, M. M.; Baden, C. W.; Balco, G.; Shuster, D. L.

    2014-12-01

    Numerical models successfully simulate LGM glacier extents in the Sierra Nevada, California, over a large range of precipitation and temperature combinations (Kessler et al. 2006, J. Geophys. Res., 111, F02002, doi:10.1029/2005JF000365). We use cosmogenic noble gas paleothermometry on samples from summit flats in the Sierra Nevada to estimate temperatures during the last glacial period in this region and further constrain the climatological predictions of these models. Cosmogenic noble gas paleothermometry utilizes the open-system behavior of cosmogenic noble gases at surface temperatures in common minerals like quartz to quantify the thermal histories of rocks during exposure to cosmic ray particles at the Earth's surface. We sampled boulders and bedrock tors atop summit flats inferred to be exposed throughout the last glacial period and measured cosmogenic 3He and 21Ne concentrations in quartz from these samples. We use cosmogenic 21Ne, which is quantitatively retained at Earth surface temperatures in quartz, to constrain exposure durations and erosion rates, and cosmogenic 3He, which exhibits open-system behavior in quartz, to quantify time-integrated temperatures during surface exposure. Data from samples collected at the summit of Mt. Langley in the southern Sierra Nevada indicate that 30-45% of the cosmogenic 3He produced in quartz has been retained at surface exposure temperatures; the rest has been diffusively lost. Preliminary models using these data and published diffusion kinetics indicate that the difference between modern and LGM summit temperatures may be significantly greater than the 5.6°C difference predicted by Kessler et al. (2006). We would expect significantly less 3He to be retained if average temperatures were 5.6°C lower at the LGM. Additional cosmogenic noble gas measurements on samples from this site and other sites in the Sierra Nevada and White Mountains as well as sample-specific diffusion kinetics will enable us to quantify this difference more precisely.

  11. A Philippinite with an Unusually Large Bubble: Gas Pressure and Noble Gas Composition

    NASA Astrophysics Data System (ADS)

    Matsuda, J.; Maruoka, T.; Pinti, D. L.; Koeberl, C.

    1995-09-01

    Bubbles are common in tektites, but usually their sizes range up to only a few mm. They are most abundant in Muong Nong-type tektites. The gases contained in these bubbles are of terrestrial atmospheric composition, with pressures below 1 atm (e.g., [1]). The abundances of light noble gases (He, Ne) are controlled by diffusion from the atmosphere [2], and noble gases dissolved in tektite glass indicate that the glass solidified at atmospheric pressures equivalent to about 40 km altitude [3]. Large bubbles in splash-form tektites are rather rare. Thus, the finding that a philippinite (size: 6.0 x 4.5 cm; weight: 199.6 g) contains an unusually large bubble justified a detailed study. The volume of the bubble, which was confirmed by X-ray photography, was estimated at 5.4 cm^3, by comparing the density of this tektite (2.288 g/cm^3) to that of normal philippinites (2.438 g/cm^3). A device was specifically constructed for crushing the present sample under vacuum. The 10x10 cm cylindrical device has a piston that allows to gently crush the sample by turning a handle. Various disk spacers can be used to adjust the inner height to that of the sample. The device is made of stainless steel, yielding a low noble gas blank. The crushing device is connected to a purification line and a noble gas sector-type mass spectrometer (VG 5400) [4]. Before crushing, the complete tektite was wrapped in aluminum foil. A first crushing attempt, using stainless steel disk spacers, failed and resulted in damage to the steel spacers, indicating a high strength of the tektite. Using iron disk spacers resulted in an ambient pressure increase (probably due to hydrogen from the Fe) in the sample chamber. However, the noble gas blanks were negligible. The background pressure, at 2 x 10-4 Torr, increased to 3 x 10-4 Torr when the sample was crushed. From the volume of the crushing device and that of the bubble in the tektite, the total gas pressure in the bubble was estimated at about 1 x 10-4 atm. Part of the extracted gas was kept for total gas analysis, while the remainder has been purified for the noble gas measurements. Total amounts and isotopic ratios of all noble gases were measured. The amounts of Ar, Kr, and Xe close to the blank level, while those of He and Ne were about 3 to 4 orders of magnitude larger than the blank. The ^20Ne/^36Ar ratio in the bubble gas is more than 4 orders of magnitude higher than the atmospheric value, which is similar to the pattern previously observed in tektites [2,3,5]. The isotopic ratios of Ar, Kr and Xe were, within uncertainties, similar to those of the terrestrial atmosphere. However, the Ne isotopic ratios were significantly different from atmospheric values, and differ from the results reported in previous studies [2,5]. The Ne isotope data seem to lie on the mass fractionation line from the atmosphere in a ^20Ne/^22Ne vs. ^21Ne/^22Ne three isotope plot, suggesting that the Ne in the bubble has diffused in from the atmosphere. However, it is generally believed that the isotopic fractionation during a steady state is very small, and the observed Ne values are higher than those calculated from simple mass fractionation [6]. The high isotopic fractionation is likely to be associated with the non-equilibrium conditions prevailing during tektite formation. Acknowledgments: We are grateful to D. Heinlein for bringing the precious sample to our attention and for allowing its analysis. References: [1] Jessberger E. K. and Gentner W. (1972) EPSL, 14, 221-225. [2] Matsubara K. and Matsuda J. (1991) Meteoritics, 26, 217-220. [3] Matsuda J. et al. (1993) Meteoritics, 28, 586-599. [4] Maruoka T. and Matsuda J. (1995) J. Mass Spectrom. Soc. Jpn., 43, 1-8. [5] Hennecke et al. (1975) JGR, 80, 2931-2934. [6] Kaneoka I., EPSL, 48, 284-292.

  12. 40 CFR 86.1314-94 - Analytical gases.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines; Gaseous and Particulate Exhaust Test Procedures... CO2. respectively, using nitrogen as the diluent. (b) Gases for the hydrocarbon analyzer shall be: (1... named as NOX with a maximum NO2 concentratio