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Sample records for noble gas atoms

  1. Polarized Electron-Noble Gas Atom Collisions

    NASA Astrophysics Data System (ADS)

    Wijayaratna, Kanishka Palipana

    In this first study of inelastic collisions of transversely polarized electrons and noble gas atoms, the importance of integrated Stokes parameter measurements of the emitted radiation for untangling various atomic interactions such as those due to Coulomb and spin-orbit forces, and exchange, is discussed. A complete theoretical formulation based on the angular momentum algebra under the L-S coupling is presented and the experimental results are compared with the results of the above calculations and also with the results of the first-order distorted -wave Born approximation (DWB1) theory. In addition, this study represents the first careful attempts made to observe inelastic "Mott scattering" optically via measurements of the Stokes parameter eta _1 for the well L-S coupled excited state, np^5(n+1)p[ 5/2]_3( ^3D_3), where n = 2, 3, 4, and 5 for Ne, Ar, Kr, and Xe respectively. We also studied the breakdown of L-S coupling in a non-well L-S coupled excited state, 4p^55p[ 5/2]_2 in Kr, due to the presence of strong spin-orbit forces within the atom. The optical excitation function measurements of all the above states and the 3^3P_ {J} state of He are presented. Most importantly, the polarimeter expressions for the first heavy noble gas optical electron polarimeters based on the exchange excitation of the np^5(n+1)p[ 5/2] _3(^3D_3) states by polarized electrons are derived and their validity is tested via measurements of eta_1. Their efficiencies are compared with that of an already existing He optical electron polarimeter. Moreover, the effectiveness of a Kr optical electron polarimeter is tested via a comparison -calibration measurement of an inline Mott polarimeter in addition to a measurement done with a He optical electron polarimeter.

  2. Atomic forces between noble gas atoms, alkali ions, and halogen ions for surface interactions

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Outlaw, R. A.; Heinbockel, J. H.

    1988-01-01

    The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base developed from analysis of the two-body potential data, the alkali-halide molecular data, and the noble gas crystal and salt crystal data. A satisfactory global fit to this molecular and crystal data is then reproduced by the model to within several percent. Surface potentials are evaluated for noble gas atoms on noble gas surfaces and salt crystal surfaces with surface tension neglected. Within this context, the noble gas surface potentials on noble gas and salt crystals are considered to be accurate to within several percent.

  3. Atomic forces between noble gas atoms, alkali ions, and halogen ions for surface interactions

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Outlaw, R. A.; Heinbockel, J. H.

    1988-01-01

    The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base developed from analysis of the two-body potential data, the alkali-halide molecular data, and the noble gas crystal and salt crystal data. A satisfactory global fit to this molecular and crystal data is then reproduced by the model to within several percent. Surface potentials are evaluated for noble gas atoms on noble gas surfaces and salt crystal surfaces with surface tension neglected. Within this context, the noble gas surface potentials on noble gas and salt crystals are considered to be accurate to within several percent.

  4. Resonance ionization spectroscopy: counting noble-gas atoms

    SciTech Connect

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

    1981-06-01

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

  5. Cucurbit[6]uril: A Possible Host for Noble Gas Atoms.

    PubMed

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

    2015-08-27

    Density functional and ab initio molecular dynamics studies are carried out to investigate the stability of noble gas encapsulated cucurbit[6]uril (CB[6]) systems. Interaction energy, dissociation energy and dissociation enthalpy are calculated to understand the efficacy of CB[6] in encapsulating noble gas atoms. CB[6] could encapsulate up to three Ne atoms having dissociation energy (zero-point energy corrected) in the range of 3.4-4.1 kcal/mol, whereas due to larger size, only one Ar or Kr atom encapsulated analogues would be viable. The dissociation energy value for the second Ar atom is only 1.0 kcal/mol. On the other hand, the same for the second Kr is -0.5 kcal/mol, implying the instability of the system. The noble gas dissociation processes are endothermic in nature, which increases gradually along Ne to Kr. Kr encapsulated analogue is found to be viable at room temperature. However, low temperature is needed for Ne and Ar encapsulated analogues. The temperature-pressure phase diagram highlights the region in which association and dissociation processes of Kr@CB[6] would be favorable. At ambient temperature and pressure, CB[6] may be used as an effective noble gas carrier. Wiberg bond indices, noncovalent interaction indices, electron density, and energy decomposition analyses are used to explore the nature of interaction between noble gas atoms and CB[6]. Dispersion interaction is found to be the most important term in the attraction energy. Ne and Ar atoms in one Ng entrapped analogue are found to stay inside the cavity of CB[6] throughout the simulation at 298 K. However, during simulation Ng2 units in Ng2@CB[6] flip toward the open faces of CB[6]. After 1 ps, one Ne atom of Ne3@CB[6] almost reaches the open face keeping other two Ne atoms inside. At lower temperature (77 K), all the Ng atoms in Ngn@CB[6] remain well inside the cavity of CB[6] throughout the simulation time (1 ps).

  6. Confinement induced binding of noble gas atoms

    NASA Astrophysics Data System (ADS)

    Khatua, Munmun; Pan, Sudip; Chattaraj, Pratim K.

    2014-04-01

    The stability of Ngn@B12N12 and Ngn@B16N16 systems is assessed through a density functional study and ab initio simulation. Although they are found to be thermodynamically unstable with respect to the dissociation of individual Ng atoms and parent cages, ab initio simulation reveals that except Ne2@B12N12 they are kinetically stable to retain their structures intact throughout the simulation time (500 fs) at 298 K. The Ne2@B12N12 cage dissociates and the Ne atoms get separated as the simulation proceeds at this temperature but at a lower temperature (77 K) it is also found to be kinetically stable. He-He unit undergoes translation, rotation and vibration inside the cavity of B12N12 and B16N16 cages. Electron density analysis shows that the He-He interaction in He2@B16N16 is of closed-shell type whereas for the same in He2@B12N12 there may have some degree of covalent character. In few cases, especially for the heavier Ng atoms, the Ng-N/B bonds are also found to have some degree of covalent character. But the Wiberg bond indices show zero bond order in He-He bond and very low bond order in cases of Ng-N/B bonds. The energy decomposition analysis further shows that the ΔEorb term contributes 40.9% and 37.3% towards the total attraction in the He2 dimers having the same distances as in He2@B12N12 and He2@B16N16, respectively. Therefore, confinement causes some type of orbital interaction between two He atoms, which akins to some degree of covalent character.

  7. Confinement induced binding of noble gas atoms

    SciTech Connect

    Khatua, Munmun; Pan, Sudip; Chattaraj, Pratim K.

    2014-04-28

    The stability of Ng{sub n}@B{sub 12}N{sub 12} and Ng{sub n}@B{sub 16}N{sub 16} systems is assessed through a density functional study and ab initio simulation. Although they are found to be thermodynamically unstable with respect to the dissociation of individual Ng atoms and parent cages, ab initio simulation reveals that except Ne{sub 2}@B{sub 12}N{sub 12} they are kinetically stable to retain their structures intact throughout the simulation time (500 fs) at 298 K. The Ne{sub 2}@B{sub 12}N{sub 12} cage dissociates and the Ne atoms get separated as the simulation proceeds at this temperature but at a lower temperature (77 K) it is also found to be kinetically stable. He-He unit undergoes translation, rotation and vibration inside the cavity of B{sub 12}N{sub 12} and B{sub 16}N{sub 16} cages. Electron density analysis shows that the He-He interaction in He{sub 2}@B{sub 16}N{sub 16} is of closed-shell type whereas for the same in He{sub 2}@B{sub 12}N{sub 12} there may have some degree of covalent character. In few cases, especially for the heavier Ng atoms, the Ng-N/B bonds are also found to have some degree of covalent character. But the Wiberg bond indices show zero bond order in He-He bond and very low bond order in cases of Ng-N/B bonds. The energy decomposition analysis further shows that the ΔE{sub orb} term contributes 40.9% and 37.3% towards the total attraction in the He{sub 2} dimers having the same distances as in He{sub 2}@B{sub 12}N{sub 12} and He{sub 2}@B{sub 16}N{sub 16}, respectively. Therefore, confinement causes some type of orbital interaction between two He atoms, which akins to some degree of covalent character.

  8. Analysis of the physical atomic forces between noble gas atoms, alkali ions and halogen ions

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Heinbockel, J. H.; Outlaw, R. A.

    1986-01-01

    The physical forces between atoms and molecules are important in a number of processes of practical importance, including line broadening in radiative processes, gas and crystal properties, adhesion, and thin films. The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base for the dispersion forces is developed from the literature based on evaluations with the harmonic oscillator dispersion model for higher order coefficients. The Zener model of the repulsive core is used in the context of the recent asymptotic wave functions of Handler and Smith; and an effective ionization potential within the Handler and Smith wave functions is defined to analyze the two body potential data of Waldman and Gordon, the alkali-halide molecular data, and the noble gas crystal and salt crystal data. A satisfactory global fit to this molecular and crystal data is then reproduced by the model to within several percent. Surface potentials are evaluated for noble gas atoms on noble gas and salt crystal surfaces with surface tension neglected. Within this context, the noble gas surface potentials on noble gas and salt crystals are considered to be accurate to within several percent.

  9. Interaction of the Fe + cation with heavy noble gas atoms

    NASA Astrophysics Data System (ADS)

    Heinemann, Christoph; Schwarz, Joseph; Koch, Wolfram; Schwarz, Helmut

    1995-09-01

    The diatomic iron-noble gas complexes FeAr+, FeKr+, FeXe+, and FeRn+ have been theoretically investigated by means of quantum-chemical calculations including an extensive treatment of electron correlation. Potential energy curves and spectroscopic constants for the lowest 4Δ and 6Δ states are derived from an open-shell coupled-cluster approach and the relative energies of all seven low-lying electronic states are evaluated by the multireference configuration interaction method. While in FeAr+ the lowest quartet and sextet states are found to be energetically almost degenerate, the heavier Fe+-noble gas molecules are predicted to exhibit 4Φ ground states. From a qualitative point of view bonding in these species is shown to be electrostatic in origin with intrinsically higher interaction energies for the quartet as compared to the sextet states. For calibration purposes, also an accurate calculation of the 4F(4s03d7)-6D(4s13d6) energy difference in the atomic Fe+ cation is provided.

  10. 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.

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

    PubMed

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

    2002-03-22

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

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

    SciTech Connect

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

    2002-03-22

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

  13. Method and apparatus for noble gas atom detection with isotopic selectivity

    DOEpatents

    Hurst, G. Samuel; Payne, Marvin G.; Chen, Chung-Hsuan; Parks, James E.

    1984-01-01

    Apparatus and methods of operation are described for determining, with isotopic selectivity, the number of noble gas atoms in a sample. The analysis is conducted within an evacuated chamber which can be isolated by a valve from a vacuum pumping system capable of producing a pressure of 10.sup.-8 Torr. Provision is made to pass pulses of laser beams through the chamber, these pulses having wavelengths appropriate for the resonance ionization of atoms of the noble gas under analysis. A mass filter within the chamber selects ions of a specific isotope of the noble gas, and means are provided to accelerate these selected ions sufficiently for implantation into a target. Specific types of targets are discussed. An electron measuring device produces a signal relatable to the number of ions implanted into the target and thus to the number of atoms of the selected isotope of the noble gas removed from the gas sample. The measurement can be continued until a substantial fraction, or all, of the atoms in the sample have been counted. Furthermore, additional embodiments of the apparatus are described for bunching the atoms of a noble gas for more rapid analysis, and for changing the target for repetitive cycling of the gas in the chamber. The number of repetitions of the cyclic steps depend upon the concentration of the isotope of interest, the separative efficiency of the mass filter, etc. The cycles are continued until a desired selectivity is achieved. Also described are components and a method of operation for a pre-enrichment operation for use when an introduction of a total sample would elevate the pressure within the chamber to levels in excess of those for operation of the mass filter, specifically a quadrupole mass filter. Specific examples of three noble gas isotope analyses are described.

  14. Method and apparatus for noble gas atom detection with isotopic selectivity

    SciTech Connect

    Hurst, G.S.; Payne, M.G.; Chen, C.H.; Parks, J.E.

    1984-01-17

    Apparatus and methods of operation are described for determining, with isotopic selectivity, the number of noble gas atoms in a sample. The analysis is conducted within an evacuated chamber which can be isolated by a valve from a vacuum pumping system capable of producing a pressure of 10[sup [minus]8] Torr. Provision is made to pass pulses of laser beams through the chamber, these pulses having wavelengths appropriate for the resonance ionization of atoms of the noble gas under analysis. A mass filter within the chamber selects ions of a specific isotope of the noble gas, and means are provided to accelerate these selected ions sufficiently for implantation into a target. Specific types of targets are discussed. An electron measuring device produces a signal relatable to the number of ions implanted into the target and thus to the number of atoms of the selected isotope of the noble gas removed from the gas sample. The measurement can be continued until a substantial fraction, or all, of the atoms in the sample have been counted. Furthermore, additional embodiments of the apparatus are described for bunching the atoms of a noble gas for more rapid analysis, and for changing the target for repetitive cycling of the gas in the chamber. The number of repetitions of the cyclic steps depend upon the concentration of the isotope of interest, the separative efficiency of the mass filter, etc. The cycles are continued until a desired selectivity is achieved. Also described are components and a method of operation for a pre-enrichment operation for use when an introduction of a total sample would elevate the pressure within the chamber to levels in excess of those for operation of the mass filter, specifically a quadrupole mass filter. Specific examples of three noble gas isotope analyses are described. 4 figs.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  16. First-principles study of noble gas atoms in bcc Fe

    NASA Astrophysics Data System (ADS)

    Zhang, Pengbo; Ding, Jianhua; Sun, Dan; Zhao, Jijun

    2017-08-01

    We investigate the energetics and clustering trend of noble gas atoms (He, Ne, and Ar) in bcc Fe, and their interactions with vacancy or H/He impurities using first-principles calculations. We determine the formation energy of single and double noble gas atoms inside Fe host lattice as well as the resulted volume changes. The Ne/Ar formation energy is two and three times that of He. The attraction between Ne/Ar and vacancy is stronger than He-vacancy, indicating higher dissolution energy of Ne/Ar. The interstitial Ne-Ne/Ar-Ar pairs have stronger attractions (-1.91 eV/-1.40 eV) than He-He (-0.37 eV), forming stable <110> configurations. Such strong attraction means that He/Ne/Ar tend to aggregate, which can be well explained by the lower electron density induced by interstitial noble gas atoms and its strong repulsion with Fe atoms. Moreover, H/He energetically prefers to occupy the tetrahedral sites nearby Ne/Ar atom. The attraction energies of He-Ne/He-Ar pairs (-1.01 eV/-0.85 eV) are much stronger than those of H-Ne/H-Ar (-0.22 eV/-0.10 eV) and their charge density differences are discussed. The distinct attraction strengths by various noble gas atoms provide a preliminary explanation for the difference in irradiation effects on Fe solid by He, Ne, Ar, and He+H/Ne+He. These findings improve our understanding about the behavior of noble gas atoms and gas bubble formation in iron under irradiation.

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

    NASA Astrophysics Data System (ADS)

    Marler, J. P.

    2005-05-01

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

  18. Confinement induced binding in noble gas atoms within a BN-doped carbon nanotube

    NASA Astrophysics Data System (ADS)

    Chakraborty, Debdutta; Chattaraj, Pratim Kumar

    2015-02-01

    Confinement induced binding interaction patterns for noble gas atoms (Hen/m, Arn, Krn; n = 2, m = 3) atoms inside pristine and -BN doped (3, 3) single walled carbon nanotube (SWCNT) have been studied through density functional theory calculations. The kinetic stability for He dimer and trimer has been investigated at 100 K and 300 K through an ab initio molecular dynamics simulation. The positive role of doping in SWCNT in enhancing the nature of interaction as well as the kinetic stability of the said systems has been found.

  19. Investigating the nature of noble gas-copper bonds by the quantum theory of atoms in molecules.

    PubMed

    Rodrigues, Eduardo F F; de Sá, Eduardo L; Haiduke, Roberto L A

    2010-04-22

    We investigated noble gas-copper bonds in linear complexes represented by the NgCuX general formula in which Ng and X stand for a noble gas (neon, argon, krypton, or xenon) and a halogen (fluorine, chlorine or bromine), respectively, by coupled cluster methods and modified cc-pVQZ basis sets. The quantum theory of atoms in molecules (QTAIM) shows a linear relation between the dissociation energy of noble gas-copper bonds and the amount of electronic charge transferred mainly from the noble gas to copper during complexation. Large changes in the QTAIM quadrupole moments of copper and noble gases resulting from this bonding and a comparison between NgCuX and NgNaCl systems indicate that these noble gas-copper bonds should be better interpreted as predominantly covalent. Finally, QTAIM atomic dipoles of noble gases in NgNaCl systems agree satisfactorily with atomic dipoles given by a simple model for these NgNa van der Waals bonds.

  20. Formation of noble-gas hydrides and decay of solvated protons revisited: diffusion-controlled reactions and hydrogen atom losses in solid noble gases.

    PubMed

    Tanskanen, Hanna; Khriachtchev, Leonid; Lignell, Antti; Räsänen, Markku; Johansson, Susanna; Khyzhniy, Ivan; Savchenko, Elena

    2008-02-07

    UV photolysis and annealing of C2H2/Xe, C2H2/Xe/Kr, and HBr/Xe matrices lead to complicated photochemical processes and reactions. The dominating products in these experiments are noble-gas hydrides with general formula HNgY (Ng = noble-gas atom, Y = electronegative fragment). We concentrate on distinguishing the local and global mobility and losses of H atoms, barriers of the reactions, and the decay of solvated protons. Different deposition temperatures change the amount of lattice imperfections and thus the amount of traps for H atoms. The averaged distance between reacting species influencing the reaction kinetics is controlled by varying the precursor concentration. A number of solid-state processes connected to the formation of noble-gas hydrides and decay of solvated protons are discussed using a simple kinetic model. The most efficient formation of noble-gas hydrides is connected with global (long-range) mobility of H atoms leading to the H + Xe + Y reaction. The highest concentration of noble-gas hydrides was obtained in matrices of highest optical quality, which probably have the lowest concentration of defects and H-atom losses. In matrices with high amount of geometrical imperfections, the product formation is inefficient and dominated by a local (short-range) process. The decay of solvated protons is rather local than a global process, which is different from the formation of noble-gas molecules. However, the present data do not allow distinguishing local proton and electron mobilities. Our previous results indicate that these are electrons which move to positively-charged centers and neutralize them. It is believed that the image obtained here for solid xenon is applicable to solid krypton whereas the case of argon deserves special attention.

  1. Noble gas magnetic resonator

    DOEpatents

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

    2014-04-15

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

  2. Noble metal atoms doped phosphorene: electronic properties and gas adsorption ability

    NASA Astrophysics Data System (ADS)

    Yu, Qi-Hang; Jiang, Yong; Zhang, Wei; Wu, Bo-Zhao; Yin, Jiu-Ren; Zhang, Ping; Ding, Yan-Huai

    2017-04-01

    Phosphorene, a 2D material, holds great promise for applications in optoelectronics and gas adsorption. The electronic structure and gas adsorption ability of phosphorene doped with three noble metal atoms (Ag, Au, Pt) are simulated by first-principles calculations based on density functional theory (DFT). Our DFT calculations reveal that doped phosphorene has low formation energies (or high adsorption energies). Doping also tailor the band gap of phosphorene, and cause the electronic properties to change. NO and CO molecules are physisorbed on both pristine and doped phosphorene, visible through their high adsorption energies and charge transfer values. Pt doped structure shows the highest adsorption energy for NO and CO molecules. The results are highly helpful to design gas sensors based on Pt doped phosphorene.

  3. Noble gas-actinide complexes of the CUO molecule with multiple Ar, Kr, and Xe atoms in noble-gas matrices.

    PubMed

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

    2003-03-12

    Laser-ablated U atoms react with CO in excess argon to produce CUO, which is trapped in a triplet state in solid argon at 7 K, based on agreement between observed and relativistic density functional theory (DFT) calculated isotopic frequencies ((12)C(16)O, (13)C(16)O, (12)C(18)O). This observation contrasts a recent neon matrix investigation, which trapped CUO in a linear singlet state calculated to be about 1 kcal/mol lower in energy. Experiments with krypton and xenon give results analogous to those with argon. Similar work with dilute Kr and Xe in argon finds small frequency shifts in new four-band progressions for CUO in the same triplet states trapped in solid argon and provides evidence for four distinct CUO(Ar)(4-n)(Ng)(n) (Ng = Kr, Xe, n = 1, 2, 3, 4) complexes for each Ng. DFT calculations show that successively higher Ng complexes are responsible for the observed frequency progressions. This work provides the first evidence for noble gas-actinide complexes, and the first example of neutral complexes with four noble gas atoms bonded to one metal center.

  4. High harmonic generation by halogen anions and noble gas atoms in a laser field

    NASA Astrophysics Data System (ADS)

    Ostrovsky, V. N.; Greenwood, J. B.

    2005-06-01

    A comparative study of high harmonic generation (HHG) by atoms and ions with active p-electrons is carried out in the theoretical framework of the rescattering mechanism. The substate with mell = 0, i.e. zero orbital momentum projection along the electric vector of a linearly polarized laser wave, is found to give the major contribution to the HHG rate. Our calculations for HHG by an H atom in an excited 2p-state demonstrate that the rate for recombination into a final state with a different value of mell (=±1), is higher for lower harmonic orders N, while for higher N (beyond the plateau domain) the difference vanishes. For species with closed electron shells, the mell-changing transitions are forbidden by the Pauli exclusion principle. We report absolute HHG rates for halogen ions and noble gas atoms at various intensities. These results demonstrate that the Coulomb binding potential of the atoms considerably enhances both the ionization and recombination steps in the rescattering process. However, the weak binding energy of the anions allows lower orders of HHG to be efficiently produced at relatively low intensities, from which we conclude that observation of HHG by an anion is experimentally feasible.

  5. Communication: Nuclear quadrupole moment-induced Cotton-Mouton effect in noble gas atoms

    SciTech Connect

    Fu, Li-juan; Vaara, Juha; Rizzo, Antonio

    2013-11-14

    New, high-sensitivity and high-resolution spectroscopic and imaging methods may be developed by exploiting nuclear magneto-optic effects. A first-principles electronic structure formulation of nuclear electric quadrupole moment-induced Cotton-Mouton effect (NQCME) is presented for closed-shell atoms. In NQCME, aligned quadrupole moments alter the index of refraction of the medium along with and perpendicular to the direction of nuclear alignment. The roles of basis-set convergence, electron correlation, and relativistic effects are investigated for three quadrupolar noble gas isotopes: {sup 21}Ne, {sup 83}Kr, and {sup 131}Xe. The magnitude of the resulting ellipticities is predicted to be 10{sup −4}–10{sup −6} rad/(M cm) for fully spin-polarized nuclei. These should be detectable in the Voigt setup. Particularly interesting is the case of {sup 131}Xe, in which a high degree of spin polarization can be achieved via spin-exchange optical hyperpolarization.

  6. Noble gas clusters in model zeolite cavities

    NASA Astrophysics Data System (ADS)

    Li, Feng Yin; Berry, R. Stephen

    1993-03-01

    Noble gas atoms trapped in the intracrystalline cavities of zeolites may form clusters. A classical-mechanical isoenergetic molecular dynamics simulation is performed to simulate the dynamical behavior of noble gas clusters in zeolite cavities. To implement the simulation, a model is adopted of a homogeneous spherical cavity with Morse interaction between the noble gas atoms and cavity walls. The results for Ar6 clusters indicate that the noble gas clusters in the cavity undergo the same solid/liquid phase changes as in free space, and, at high enough energies, a rapid exchange between atoms adsorbed on the inner surface and thosein the interior of the cavity. Mathematical quenching is used to investigated the multidimensional potential surface of Ar clusters in the cavity.

  7. Ultrabright multikilovolt x-ray source: saturated amplification on noble gas transition arrays from hollow atom states

    DOEpatents

    Rhodes, Charles K.; Boyer, Keith

    2004-02-17

    An apparatus and method for the generation of ultrabright multikilovolt x-rays from saturated amplification on noble gas transition arrays from hollow atom states is described. Conditions for x-ray amplification in this spectral region combine the production of cold, high-Z matter, with the direct, selective multiphoton excitation of hollow atoms from clusters using ultraviolet radiation and a nonlinear mode of confined, self-channeled propagation in plasmas. Data obtained is consistent with the presence of saturated amplification on several transition arrays of the hollow atom Xe(L) spectrum (.lambda..about.2.9 .ANG.). An estimate of the peak brightness achieved is .about.10.sup.29 .gamma..multidot.s.sup.-1.multidot.mm.sup.-2.multidot.mr.sup.-2 (0.1% Bandwidth).sup.-1, that is .about.10.sup.5 -fold higher than presently available synchotron technology.

  8. 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

  9. Cosmogenic noble gas paleothermometry

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  10. 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 Møller-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.

  11. Quantum dynamics of an excited alkali atom in a noble gas cluster: lithium attached to a helium cluster.

    PubMed

    Pacheco, Alexander B; Thorndyke, Brian; Reyes, Andrés; Micha, David A

    2007-12-28

    An alkali atom-noble gas cluster system is considered as a model for solvation effects in optical spectra, within a quantum-classical description based on the density operator of a many-atom system and its partial Wigner transform. This leads to an eikonal-time-dependent molecular orbital treatment suitable for a time-dependent description of the coupling of light emission and atom dynamics in terms of the time-dependent electric dipole of the whole system. As an application, we consider an optically excited lithium atom as the dopant in a helium cluster at 0.5 K. We describe the motions of the excited Li atom interacting with a cluster of He atoms and calculate the time-dependent electric dipole of the Li-He(99) system during the dynamics. The electronic Hamiltonian is taken as a sum of three-body Li-He diatomic potentials including electronic polarization and repulsion, with l-dependent atomic pseudopotentials for Li and He, while we use a modified pair potential for He-He. The calculations involve the coupling of 12 quantum states with 300 classical degrees of freedom. We present results for the dynamics and spectra of a Li atom interacting with a model cluster surface of He atoms and also interacting with a droplet of He. We have found that the Li atom is attracted or repulsed from the He surface, depending on the orientation of its 2p orbitals. The spectra and dynamics of Li inside and at the surface of a cluster are found to be strongly dependent on its electronic states, its velocity direction, and whether light is present during emission or not.

  12. Updated compilations of electron scattering from ground-state, noble gas atoms

    NASA Astrophysics Data System (ADS)

    Biagi, S. F.

    2011-10-01

    An updated analysis of the cross sections for electron scattering from ground state atoms for noble gases in the energy range from thermalto 10 MeV is outlined. The work was driven by the necessity tounderstand the Penning transfers and light emission in detectors of high energy particles and dark matter. The published experimental data for electron scattering up to 2010 have been used in the analysis. Recent, theoretically improved cross sections have been used in the important threshold region for both the singlet and triplet states. Experimental or theoretical oscillator strengths and BEF scaling have been used above the resonance region for the singlet states. The number of excitation levels considered (typically about 40) is chosen so that the sum of the oscillator strengths for the considered levels is within a few percent of the theoretical sum rule. The resulting total cross sections are within a few percent of the measured values, and the calculated Fano factors are consistent with available data. These data are now available on the LXCat website. This work is part of the RD51 collaboration at CERN.

  13. Coordination of ScO+ and YO+ by multiple Ar, Kr, and Xe atoms in noble gas matrixes: a matrix isolation infrared spectroscopic and theoretical study.

    PubMed

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

    2005-12-29

    The combination of matrix isolation infrared spectroscopic and quantum chemical calculation results provide strong evidence that scandium and yttrium monoxide cations, ScO+ and YO+, coordinate multiple noble gas atoms in forming noble gas complexes. The results showed that ScO+ coordinates five Ar, Kr, or Xe atoms, and YO+ coordinates six Ar or Kr and five Xe atoms in solid noble gas matrixes. Hence, the ScO+ and YO+ cations trapped in solid noble gas matrixes should be regarded as the [ScO(Ng)5]+ (Ng = Ar, Kr, or Xe), [YO(Ng)6]+ (Ng = Ar or Kr) or [YO(Xe)5]+ complexes. Experiments with dilute krypton or xenon in argon or krypton in xenon produced new IR bands, which are due to the stepwise formation of the [ScO(Ar)(5-n)(Kr)n]+, [ScO(Kr)(5-n)(Xe)n]+ (n = 1-5), [YO(Ar)(6-n)(Kr)n]+ (n = 1-6), and [YO(Ar)(6-n)(Xe)n]+ (n = 1-4) complexes.

  14. Noble gas fractionation during subsurface gas migration

    NASA Astrophysics Data System (ADS)

    Sathaye, Kiran J.; Larson, Toti E.; Hesse, Marc A.

    2016-09-01

    Environmental monitoring of shale gas production and geological carbon dioxide (CO2) storage requires identification of subsurface gas sources. Noble gases provide a powerful tool to distinguish different sources if the modifications of the gas composition during transport can be accounted for. Despite the recognition of compositional changes due to gas migration in the subsurface, the interpretation of geochemical data relies largely on zero-dimensional mixing and fractionation models. Here we present two-phase flow column experiments that demonstrate these changes. Water containing a dissolved noble gas is displaced by gas comprised of CO2 and argon. We observe a characteristic pattern of initial co-enrichment of noble gases from both phases in banks at the gas front, followed by a depletion of the dissolved noble gas. The enrichment of the co-injected noble gas is due to the dissolution of the more soluble major gas component, while the enrichment of the dissolved noble gas is due to stripping from the groundwater. These processes amount to chromatographic separations that occur during two-phase flow and can be predicted by the theory of gas injection. This theory provides a mechanistic basis for noble gas fractionation during gas migration and improves our ability to identify subsurface gas sources after post-genetic modification. Finally, we show that compositional changes due to two-phase flow can qualitatively explain the spatial compositional trends observed within the Bravo Dome natural CO2 reservoir and some regional compositional trends observed in drinking water wells overlying the Marcellus and Barnett shale regions. In both cases, only the migration of a gas with constant source composition is required, rather than multi-stage mixing and fractionation models previously proposed.

  15. Dual Species Noble Gas Nuclear Spin Polarizer for a New Search for the Atomic EDM of Xe-129 at FRM-II (Munich Research Reactor)

    NASA Astrophysics Data System (ADS)

    Cohn, Jared; Coulter, Daniel; Frisbie, Dustin; Fromm, Steven; Huneau, Jake; Rabga, Tenzin; Underwood, Walter; Singh, Jaideep; Fierlinger, Peter; Kraegeloh, Eva; Kuchler, Florian; Lins, Tobias; Marino, Mike; Meinel, Jonas; Neissen, Benjamin; Stuiber, Stefan; Fan, Isaac; Kilian, Wolfgang; Knappe-Gruenberg, Silvia; Trahms, Lutz; Chupp, Tim; Degenkolb, Skyler; Sachdeva, Natasha; Gong, Fei; Babcock, Earl; Fierlinger Group Team; Chupp Laboratory Team; Physikalisch-Technische Bundesanstalt Collaboration; Juelich CenterNeutron Science Collaboration

    2015-10-01

    Electric dipole moments are believed to be very sensitive probes of CP violation beyond the Standard Model. A new search for the atomic electric dipole moment of Xe-129 is currently underway at FRM-II in Munich. Our technique takes advantage of a state of the art magnetically shielded room, ultra-sensitive magnetometry using SQUIDs, and control of systematics using a He-3 co-magnetometer. Our goal is an order of magnitude improvement over the previous Xe-129 atomic EDM limit. We will describe the design and construction of a noble gas polarizer using spectrally-narrow diode lasers. Technische Universitaet Muenchen.

  16. In quest of a superhalogen supported covalent bond involving a noble gas atom.

    PubMed

    Chakraborty, Debdutta; Chattaraj, Pratim Kumar

    2015-03-26

    The possibility of having neutral Xe-bound compounds mediated by some representative transition metal fluorides of general formula MX3 (where M=Ru, Os, Rh, Ir, Pd, Pt, Ag, Au and X=F) has been investigated through density functional theory based calculations. Nature of interaction between MX3 and Xe moieties has been characterized through detailed electron density, charge density and bond energy decomposition analyses. The feasibility of having compounds of general formula XeMX3 at 298 K has been predicted through thermodynamic considerations. The nature of interaction in between Xe and M atoms is partly covalent in nature and the orbital interaction is the dominant contributor toward these interactions as suggested by energy decomposition analysis.

  17. Interatomic potentials between noble gas and Ag atoms from axial surface channeling

    NASA Astrophysics Data System (ADS)

    Schüller, A.; Winter, H.

    2007-08-01

    He, Ne, and Ar atoms with energies from 3 keV to 60 keV are scattered from a Ag(1 1 1) surface under axial surface channeling conditions. From peaked structures in the angular distributions owing to "rainbow-scattering" we derive effective scattering potentials. We compare the observed rainbow angles with results from computer simulations using different types of established interatomic potentials and focus on a detailed discussion for potential energies larger than 10 eV. It turns out that an approximation proposed by O'Connor and Biersack using a Moliere potential with an adjustment of the screening length [D.J. O'Connor, J.P. Biersack, Nucl. Instr. and Meth. B 15 (1986) 14) is in good agreement with the experimental data. In our simulations we investigate the sensitivity of the rainbow angles on a variation of the interatomic potential.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  19. 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.

  20. 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.

  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. 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...

  3. 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...

  4. On a cryogenic noble gas ion catcher

    NASA Astrophysics Data System (ADS)

    Dendooven, P.; Purushothaman, S.; Gloos, K.

    2006-03-01

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

  5. Noble gas sputtering calculations using TRIM

    SciTech Connect

    Greene, J.P.; Nemanich, J.; Thomas, G.E.; Schiel, S.L.

    1996-12-31

    In conjunction with our experimental work on saddle field ion sputtering, we have attempted to apply the Monte Carlo program TRIM (Transport of Ions in Matter) to calculate the sputter yields for a variety of noble gas sputtering applications. Comparison with experiments are shown. Information extracted from these analyses have proved useful in optimizing the experimental sputtering parameters. Calculated sputter yields obtained utilizing TRIM are presented for noble gas sputtering of a variety of materials common to nuclear target production.

  6. Planetary noble gas components in Orgueil

    NASA Technical Reports Server (NTRS)

    Frick, U.; Moniot, R. K.

    1977-01-01

    In the reported investigation, the approach employed by Jeffery and Anders (1970) and Eberhardt (1974), who used colloidal suspensions in separating minerals of the Orgueil carbonaceous chondrite (C1), was extended to an application involving the enrichment of a planetary noble gas carrier in several C1 and C2 meteorites. The thermal release pattern of Orgueil 'carbon' is considered, taking into account elemental effects, a comparison of noble gas release from 'carbon' separates and bulk meteorite samples, isotopic effects, and a comparison with Murray 'carbon'. An evaluation is conducted of the noble gas components in carbonaceous chondrites. The origin of primordial noble gases in carbonaceous chondrites is also discussed, giving attention to the origin of solar gases, the role of 'carbon' as the novel vehicle for planetary gases, and plausible astrophysical sites for the production of anomalous krypton and xenon.

  7. First-principles study of noble gas stability in ThO2

    NASA Astrophysics Data System (ADS)

    Shao, Kuan; Han, Han; Zhang, Wei; Wang, Hui; Wang, Chang-Ying; Guo, Yong-Liang; Ren, Cui-Lan; Huai, Ping

    2017-07-01

    The stability of noble gases (He, Ne, Ar, Kr and Xe) in thorium dioxide is studied by means of density functional theory. The computations are performed considering insertion sites of ThO2, including the interstitial sites, the thorium vacancies, the oxygen-thorium di-vacancy and three types of Schottky defects. Our results show that there is an approximately linear relation between the energies and the atomic radii. As the size of the noble gas atom increases, the noble gas atoms energetically prefer to incorporate into large vacancy defects rather than into interstitial positions. Moreover, the binding energy of Kr or Xe interstitial in a Schottky defect is larger than the formation energy of a Schottky defect, suggesting the Schottky defects are thermodynamically favorable in the presence of these noble gas atoms. The charged defects are also considered for noble gas atoms trapped in Th and O vacancies.

  8. 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.

  9. Noble Gas Signatures in Snow: a New Experimental Investigation.

    NASA Astrophysics Data System (ADS)

    Amalberti, J.; Hall, C. M.; Castro, C.

    2016-12-01

    Dissolved noble gases in groundwater (He, Ne, Ar, Kr, and Xe) have been widely used to improve our knowledge of surface and groundwater dynamics. However, a recent rainwater study [1] recorded noble gas concentration anomalies originating from conditions at high altitude. Potential anomaly sources might include fog, orographic rain, synoptic rain and snow, depending on the region considered. Here, we outline a methodology for measuring noble gases in freshly collected snow samples. Their fine-grained nature leads to significant experimental challenges. Overall, our results (Fig. 1) show that snow has elevated He concentrations with depleted concentrations of all other noble gases. Similar results have been recorded in ice [2, 3]. In addition, our results show relatively homogeneous (< 14%) He and Ne concentrations while Ar, Kr and Xe display large concentration variability (> 80%). These observations led us to investigate the structure of snow and potential host-sites (available empty space) within the crystal structure. Noble gases are chemically inert and do not form bonds that could affect the ice crystal structure. Therefore, host-sites control the solubility of each noble gas. Our results show that He and Ne, which are known to have small atomic radii, are likely dissolved into the ice/snow crystal lattice, while heavy noble gas (Ar, Kr and Xe) are likely accommodated into defects. Consequently, smaller variability recorded in light noble gases, may result from He and Ne being hosted within the crystal lattice, whereas heavy noble gases rely on the presence of defects, which may randomly appear within the structure during snow formation. These new results can be used to better constrain the source of ground ice [3], groundwater systems and to investigate the structural transition mechanisms from snow to firn and ice. Figure 1: Noble gas concentrations (C) in snow (filled circles symbols) and ice (half-filled square symbols) normalized to air saturated water

  10. 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

  11. A confinement induced spectroscopic study of noble gas atoms using equation of motion architecture: Encapsulation within fullerene's voids

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Supriya K.; Chaudhuri, Rajat K.; Mukherjee, Prasanta K.; Chattopadhyay, Sudip

    2017-07-01

    A relativistic study of spectroscopic properties of the endohedral fullerenes Ng@C60q (where Ng = He, Ne and q =0 ,±1 ,±2 are the charges) associated with the C60 molecule has been done using the equation of motion coupled cluster (EOM-CC) methodology. Specific properties estimated are the transition energies, dipole oscillator strengths, and transition probabilities for the low-lying excitations 1s2(1S0) → 1 s n p (1P1) (n = 2, 3, 4) for He@C60q and 1s22s22p6 (1S0) → 1 s22 s22 p5n s /n d (1P1) (n = 3, 4) for Ne@C60q, which have been compared with those for the isolated atom to depict the confinement effect of the host molecule on the encapsulated atom. This is accomplished by introducing an effective potential to the atomic Hamiltonian induced by the fullerene moiety and its charge. The EOM-CC results have been compared with those estimated with the random phase approximation (and configuration interaction singles) to understand the effect of electron correlation under such confinement. The systematic and interesting behavior of the properties is highlighted indicating the effect of fullerene cage potential on the redistribution of electron density of the guest atom.

  12. Noble gas atmospheric monitoring at reprocessing facilities

    SciTech Connect

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

    1997-05-01

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

  13. Structure and dynamics of noble gas-halogen and noble gas ionic clusters: When theory meets experiment

    NASA Astrophysics Data System (ADS)

    Beswick, J. A.; Halberstadt, N.; Janda, K. C.

    2012-05-01

    As part of this special issue in honor of Gerardo Delgado Barrio, we have reviewed the interplay between experimental and theoretical work on halogen and interhalogen diatomic molecule bonded to one or more noble gas atoms and also ionic clusters consisting of noble gas atoms. Although the Madrid group has worked on many theoretical issues, they have made particularly important contributions to these two topics. Delgado Barrio has often chosen topics for study for which close interactions between theorists and experimentalists are especially useful. During the historical span of the group, we have progressed from approximate models whose goal was to capture the essence of a process even if the details were impossible to reproduce, to an era in which theory is an equal partner with experiment, and, in fact, often provides a detailed understanding beyond that obtained from a careful analysis of state-of-the-art data.

  14. Heuristic overlap-exchange model of noble gas chemical shifts

    NASA Astrophysics Data System (ADS)

    Adrian, Frank J.

    2004-05-01

    It is now generally recognized that overlap-exchange interactions are the primary cause of the medium-dependent magnetic shielding (chemical shift) in all noble gases except helium, although the attractive electrostatic-dispersion (van der Waals) interactions play an indirect role in determining the penetration of the interacting species into the repulsive overlap-exchange region. The short-range nature of these overlap-exchange interactions, combined with the fact that they often can be approximated by simple functions of the overlap of the wave functions of the interacting species, suggests a useful semiempirical model of these chemical shifts. In it the total shielding is the sum of shieldings due to pairwise interactions of the noble gas atom with the individual atoms of the medium, with the "atomic" shielding terms either estimated by simple functions of the atomic overlap integrals averaged over their Boltzmann-weighted separations, or determined by fits to experimental data in systems whose complexity makes the former procedure impractical. Results for 129Xe chemical shifts in the noble gases and in a variety of molecular and condensed systems, including families of n-alkanes, straight-chain alcohols, and the endohedral compounds Xe@C60 and Xe@C70 are encouraging for the applicability of the model to systems of technical and biomedical interest.

  15. Contribution of electron-atom collisions to the plasma conductivity of noble gases

    NASA Astrophysics Data System (ADS)

    Rosmej, S.; Reinholz, H.; Röpke, G.

    2017-06-01

    We present an approach which allows the consistent treatment of bound states in the context of dc conductivity in dense partially ionized noble gas plasmas. Besides electron-ion and electron-electron collisions, further collision mechanisms owing to neutral constituents are taken into account. Especially at low temperatures of 104to105 K, electron-atom collisions give a substantial contribution to the relevant correlation functions. We suggest an optical potential for the description of the electron-atom scattering which is applicable for all noble gases. The electron-atom momentum-transfer cross section is in agreement with experimental scattering data. In addition, the influence of the medium is analyzed, the optical potential is advanced including screening effects. The position of the Ramsauer minimum is influenced by the plasma. Alternative approaches for the electron-atom potential are discussed. Good agreement of calculated conductivity with experimental data for noble gas plasmas is obtained.

  16. Contribution of electron-atom collisions to the plasma conductivity of noble gases.

    PubMed

    Rosmej, S; Reinholz, H; Röpke, G

    2017-06-01

    We present an approach which allows the consistent treatment of bound states in the context of dc conductivity in dense partially ionized noble gas plasmas. Besides electron-ion and electron-electron collisions, further collision mechanisms owing to neutral constituents are taken into account. Especially at low temperatures of 10^{4}to10^{5} K, electron-atom collisions give a substantial contribution to the relevant correlation functions. We suggest an optical potential for the description of the electron-atom scattering which is applicable for all noble gases. The electron-atom momentum-transfer cross section is in agreement with experimental scattering data. In addition, the influence of the medium is analyzed, the optical potential is advanced including screening effects. The position of the Ramsauer minimum is influenced by the plasma. Alternative approaches for the electron-atom potential are discussed. Good agreement of calculated conductivity with experimental data for noble gas plasmas is obtained.

  17. Noble-Gas Atomic Interferometer

    DTIC Science & Technology

    2011-01-19

    Awards W. E. Lamb Medal for Laser Science and Quantum Optics (2008). Lewiner Distinguished Lecturer, Technion, Israel (2009). Graduate Students...effort to explain Maxwell’s demon in terms of information entropy . Single-photon cooling was demonstrated experimentally on magnetically trapped

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

    NASA Technical Reports Server (NTRS)

    Zaikowski, A.; Schaeffer, O. A.

    1979-01-01

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

  19. Noble gas encapsulation into carbon nanotubes: Predictions from analytical model and DFT studies

    SciTech Connect

    Balasubramani, Sree Ganesh; Singh, Devendra; Swathi, R. S.

    2014-11-14

    The energetics for the interaction of the noble gas atoms with the carbon nanotubes (CNTs) are investigated using an analytical model and density functional theory calculations. Encapsulation of the noble gas atoms, He, Ne, Ar, Kr, and Xe into CNTs of various chiralities is studied in detail using an analytical model, developed earlier by Hill and co-workers. The constrained motion of the noble gas atoms along the axes of the CNTs as well as the off-axis motion are discussed. Analyses of the forces, interaction energies, acceptance and suction energies for the encapsulation enable us to predict the optimal CNTs that can encapsulate each of the noble gas atoms. We find that CNTs of radii 2.98 − 4.20 Å (chiral indices, (5,4), (6,4), (9,1), (6,6), and (9,3)) can efficiently encapsulate the He, Ne, Ar, Kr, and Xe atoms, respectively. Endohedral adsorption of all the noble gas atoms is preferred over exohedral adsorption on various CNTs. The results obtained using the analytical model are subsequently compared with the calculations performed with the dispersion-including density functional theory at the M06 − 2X level using a triple-zeta basis set and good qualitative agreement is found. The analytical model is however found to be computationally cheap as the equations can be numerically programmed and the results obtained in comparatively very less time.

  20. Noble gas encapsulation into carbon nanotubes: Predictions from analytical model and DFT studies

    NASA Astrophysics Data System (ADS)

    Balasubramani, Sree Ganesh; Singh, Devendra; Swathi, R. S.

    2014-11-01

    The energetics for the interaction of the noble gas atoms with the carbon nanotubes (CNTs) are investigated using an analytical model and density functional theory calculations. Encapsulation of the noble gas atoms, He, Ne, Ar, Kr, and Xe into CNTs of various chiralities is studied in detail using an analytical model, developed earlier by Hill and co-workers. The constrained motion of the noble gas atoms along the axes of the CNTs as well as the off-axis motion are discussed. Analyses of the forces, interaction energies, acceptance and suction energies for the encapsulation enable us to predict the optimal CNTs that can encapsulate each of the noble gas atoms. We find that CNTs of radii 2.98 - 4.20 Å (chiral indices, (5,4), (6,4), (9,1), (6,6), and (9,3)) can efficiently encapsulate the He, Ne, Ar, Kr, and Xe atoms, respectively. Endohedral adsorption of all the noble gas atoms is preferred over exohedral adsorption on various CNTs. The results obtained using the analytical model are subsequently compared with the calculations performed with the dispersion-including density functional theory at the M06 - 2X level using a triple-zeta basis set and good qualitative agreement is found. The analytical model is however found to be computationally cheap as the equations can be numerically programmed and the results obtained in comparatively very less time.

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

    PubMed

    Mondal, Sukanta; Chattaraj, Pratim Kumar

    2014-09-07

    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.

  2. Spectroscopy of low-energy atoms released from a solid noble-gas matrix: Proposal for a trap-loading technique

    NASA Astrophysics Data System (ADS)

    Lambo, R.; Rodegheri, C. C.; Silveira, D. M.; Cesar, C. L.

    2007-12-01

    We have studied the velocity distribution of chromium atoms released from a solid neon matrix at cryogenic temperatures via Doppler spectroscopy. The Ne matrix is grown by directing a small flux of gas onto a cold substrate, while Cr atoms are simultaneously implanted by laser ablation, with the resultant plume directed toward the growing matrix. The atoms are then released by a heat pulse. We have observed neutral Cr atoms at temperatures around 13K with densities close to 1012cm-3 . The released atoms have a large initial drift velocity, explained by simple kinetic theory arguments, due to the light species’ drag force. The scheme could be adapted to produce cryogenic beams of atoms, molecules, and possibly ions, for collisional studies and spectroscopy. However, our main motivation was the construction of a hydrogen trap, and here we discuss the prospects and problems of using this technique for this purpose.

  3. Spectroscopy of low-energy atoms released from a solid noble-gas matrix: Proposal for a trap-loading technique

    SciTech Connect

    Lambo, R.; Rodegheri, C. C.; Silveira, D. M.; Cesar, C. L.

    2007-12-15

    We have studied the velocity distribution of chromium atoms released from a solid neon matrix at cryogenic temperatures via Doppler spectroscopy. The Ne matrix is grown by directing a small flux of gas onto a cold substrate, while Cr atoms are simultaneously implanted by laser ablation, with the resultant plume directed toward the growing matrix. The atoms are then released by a heat pulse. We have observed neutral Cr atoms at temperatures around 13 K with densities close to 10{sup 12} cm{sup -3}. The released atoms have a large initial drift velocity, explained by simple kinetic theory arguments, due to the light species' drag force. The scheme could be adapted to produce cryogenic beams of atoms, molecules, and possibly ions, for collisional studies and spectroscopy. However, our main motivation was the construction of a hydrogen trap, and here we discuss the prospects and problems of using this technique for this purpose.

  4. 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.

  5. 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

  6. 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.

  7. Using 220Rn to calibrate liquid noble gas detectors

    NASA Astrophysics Data System (ADS)

    Kobayashi, M.; Yamashita, M.; Takeda, A.; Kishimoto, K.; Moriyama, S.

    2016-07-01

    In this paper, we describe 220Rn calibration source that was developed for liquid noble gas detectors. The key advantage of this source is that it can provide 212Bi-212 Po consecutive events, which enables us to evaluate the vertex resolution of a detector at low energy by comparing low-energy events of 212Bi and corresponding higher-energy α-rays from 212Po. Since 220Rn is a noble gas, a hot metal getter can be used when introduced using xenon as the carrier gas. In addition, no long-life radioactive isotopes are left behind in the detector after the calibration is complete; this has clear advantage over the use of 222Rn which leaves longlife radioactivity, i.e., 210Pb. Using a small liquid xenon test chamber, we developed a system to introduce 220Rn via the xenon carrier gas; we demonstrated the successful introduction of 6 × 102 220Rn atoms in our test environment.

  8. PHYSICS PROCESSES IN DISRUPTION MITIGATION USING MASSIVE NOBLE GAS INJECTION

    SciTech Connect

    D.A. HUMPHREYS; D.G. WHYTE; T.C. JERNIGAN; T.E.EVANS; D.S. GRAY; E.M. HOLLMANN; A.W. HYATT; A.G. KELLMAN; C.J. LASNIER; P.B. PARKS; P.L. TAYLOR

    2002-07-01

    Methods for detecting imminent disruptions and mitigating disruption effects using massive injection of noble gases (He, Ne, or Ar) have been demonstrated on the DIII-D tokamak [1]. A jet of high injected gas density (> 10{sup 24} m{sup -3}) and pressure (> 20 kPa) penetrates the target plasma at the gas sound speed ({approx}300-500 m/s) and increases the atom/ion content of the plasma by a factor of > 50 in several milliseconds. UV line radiation from the impurity species distributes the plasma energy uniformly on the first wall, reducing the thermal load to the divertor by a factor of 10. Runaway electrons are almost completely eliminated by the large density of free and bound electrons supplied by the gas injection. The small vertical plasma displacement before current quench and high ratio of current decay rate to vertical growth rate result in a 75% reduction in peak halo current amplitude and attendant forces.

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

    PubMed

    Woodworth, M R

    1983-06-01

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

  10. LaRC results on nuclear pumped noble gas lasers

    NASA Technical Reports Server (NTRS)

    Deyoung, R. J.

    1979-01-01

    The recent experiment and theoretical results obtained for noble gas nuclear laser systems are presented. It is shown that the noble gas lasers are among the easiest systems to pump by nuclear excitation and as a result, all of the noble gases except He have lased under nuclear excitation. The noble gas systems are not ideal for high-power applications but they do give valuable insight into the operation and pumping mechanisms associated with nuclear lasers. At present, the Ar-Xe system is the best noble gas candidate for (U-235)F6 pumping. It appears that the quenching of Ar-Xe lasing is a result of the fluorine and not the uranium or fission fragments themselves. Thus, to achieve lasing with UF6, a fluorine compatible system must be found.

  11. 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

  12. The Thermochemical Stability of Ionic Noble Gas Compounds.

    ERIC Educational Resources Information Center

    Purser, Gordon H.

    1988-01-01

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

  13. 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,…

  14. Noble gas partitioning between metal and silicate under high pressures.

    PubMed

    Matsuda, J; Sudo, M; Ozima, M; Ito, K; Ohtaka, O; Ito, E

    1993-02-05

    Measurements of noble gas (helium, neon, argon, krypton, and xenon) partitioning between silicate melt and iron melt under pressures up to 100 kilobars indicate that the partition coefficients are much less than unity and that they decrease systematically with increasing pressure. The results suggest that the Earth's core contains only negligible amounts of noble gases if core separation took place under equilibrium conditions.

  15. 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.

  16. 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.

  17. The Noble Gas Fingerprint in a UK Unconventional Gas Reservoir

    NASA Astrophysics Data System (ADS)

    McKavney, Rory; Gilfillan, Stuart; Györe, Domokos; Stuart, Fin

    2016-04-01

    In the last decade, there has been an unprecedented expansion in the development of unconventional hydrocarbon resources. Concerns have arisen about the effect of this new industry on groundwater quality, particularly focussing on hydraulic fracturing, the technique used to increase the permeability of the targeted tight shale formations. Methane contamination of groundwater has been documented in areas of gas production1 but conclusively linking this to fugitive emissions from unconventional hydrocarbon production has been controversial2. A lack of baseline measurements taken before drilling, and the equivocal interpretation of geochemical data hamper the determination of possible contamination. Common techniques for "fingerprinting" gas from discrete sources rely on gas composition and isotopic ratios of elements within hydrocarbons (e.g. δ13CCH4), but the original signatures can be masked by biological and gas transport processes. The noble gases (He, Ne, Ar, Kr, Xe) are inert and controlled only by their physical properties. They exist in trace quantities in natural gases and are sourced from 3 isotopically distinct environments (atmosphere, crust and mantle)3. They are decoupled from the biosphere, and provide a separate toolbox to investigate the numerous sources and migration pathways of natural gases, and have found recent utility in the CCS4 and unconventional gas5 industries. Here we present a brief overview of noble gas data obtained from a new coal bed methane (CBM) field, Central Scotland. We show that the high concentration of helium is an ideal fingerprint for tracing fugitive gas migration to a shallow groundwater. The wells show variation in the noble gas signatures that can be attributed to differences in formation water pumping from the coal seams as the field has been explored for future commercial development. Dewatering the seams alters the gas/water ratio and the degree to which noble gases degas from the formation water. Additionally the

  18. 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.

  19. DISRUPTION MITIGATION WITH HIGH-PRESSURE NOBLE GAS INJECTION

    SciTech Connect

    WHYTE, DG; JERNIGAN, TC; HUMPHREYS, DA; HYATT, AW; LASNIER, CJ; PARKS, PB; EVANS, TE; TAYLOR, PL; KELLMAN, AG; GRAY, DS; HOLLMANN, EM

    2002-10-01

    OAK A271 DISRUPTION MITIGATION WITH HIGH-PRESSURE NOBLE GAS INJECTION. High-pressure gas jets of neon and argon are used to mitigate the three principal damaging effects of tokamak disruptions: thermal loading of the divertor surfaces, vessel stress from poloidal halo currents and the buildup and loss of relativistic electrons to the wall. The gas jet penetrates as a neutral species through to the central plasma at its sonic velocity. The injected gas atoms increase up to 500 times the total electron inventory in the plasma volume, resulting in a relatively benign radiative dissipation of >95% of the plasma stored energy. The rapid cooling and the slow movement of the plasma to the wall reduce poloidal halo currents during the current decay. The thermally collapsed plasma is very cold ({approx} 1-2 eV) and the impurity charge distribution can include > 50% fraction neutral species. If a sufficient quantity of gas is injected, the neutrals inhibit runaway electrons. A physical model of radiative cooling is developed and validated against DIII-D experiments. The model shows that gas jet mitigation, including runaway suppression, extrapolates favorably to burning plasmas where disruption damage will be more severe. Initial results of real-time disruption detection triggering gas jet injection for mitigation are shown.

  20. Laboratory Noble Gas Migration Experiments through Rock

    NASA Astrophysics Data System (ADS)

    Broome, S.; Cashion, A.; Feldman, J.; Sussman, A. J.; Swanson, E.; Wilson, J.

    2016-12-01

    The Underground Nuclear Explosion Signatures Experiment (UNESE) was created to address science and research and development aspects associated with nuclear explosion verification and nuclear nonproliferation with a focus on non-prompt signals. A critical component of the UNESE program is a realistic understanding of the post-detonation processes and changes in the environment that produce observable physical and radio-chemical signatures. As such, an understanding of noble gas migration properties through various lithologies is essential. Here we present an empirical methodology to measure tortuosity on well-characterized rhyolitic tuffs and lavas. Tortuosity is then compared with microfracture networks characterized by microscopy. To quantify tortuosity, a pressurized (1500 mbar) fixed volume of argon is expanded into a sample under high vacuum (0.200 mbar). A quadrupole mass spectrometer (QMS) is used to measure argon downstream of the sample in real time, allowing the time-series gas arrival curve to be characterized for each sample. To evaluate the method, blank samples have been machined to correspond with tortuosities of 1, 2, and 4 in conjunction with a restricted-flow valve to mimic rock sample permeability. Data from the blanks are analyzed with this system to correct for system effects on gas arrival. High vacuum is maintained in the QMS system during sampling by precise metering of the gas through a leak valve with active feedback control which allows arrival time and concentration of argon to be established in real time. Along with a comprehensive characterization of the rock and fracture properties, the parameters derived from these experiments will provide invaluable insight into the three-dimensional structure of damage zones, the production of temporally variable signatures and the methods to best detect underground nuclear explosion signatures. SAND2016-7309 A

  1. Real-time noble gas release signaling rock deformation

    NASA Astrophysics Data System (ADS)

    Bauer, S. J.; Gardner, W. P.; Lee, H.

    2016-12-01

    We present empirical results/relationships of rock strain, microfracture density, acoustic emissions, and noble gas release from laboratory triaxial experiments for a granite and basalt. Noble gases are contained in most crustal rock at inter/intra granular sites, their release during natural and manmade stress and strain changes represents a signal of brittle/semi brittle deformation. The gas composition depends on lithology, geologic history and age, fluids present, and uranium, thorium and potassium-40 concentrations in the rocks that affect radiogenic noble gases (helium, argon) production. Noble gas emission and its relationship to crustal processes have been studied, including correlations to tectonic velocities and qualitative estimates of deep permeability from surface measurements, finger prints of nuclear weapon detonation, and as potential precursory signals to earthquakes attributed to gas release due to pre-seismic stress, dilatancy and/or rock fracturing. Helium emission has been shown as a precursor of volcanic activity. Real-time noble gas release is observed using an experimental system utilizing mass spectrometers to measure gases released during triaxial rock deformation. Noble gas release is shown to represent a sensitive precursor signal of rock deformation by relating real-time noble gas release to stress-strain state changes and acoustic emissions. We propose using noble gas release to also signal rock deformation in boreholes, mines and nuclear waste repositories. We postulate each rock exhibits a gas release signature which is microstructure, stress/strain state, and or permanent deformation dependent. Such relationships, when calibrated, may be used to sense rock deformation and then develop predictive models. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corp., for the US Dept. of Energy's National Nuclear Security Administration under

  2. 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.

  3. Underground Sources of Radioactive Noble Gas

    SciTech Connect

    Hayes, James C.; Bowyer, Ted W.; Cordova, Elsa A.; Kirkham, Randy R.; Misner, Alex C.; Olsen, Khris B.; Woods, Vincent T.; Emer, Dudley

    2013-05-01

    It is well known that radon is present in relatively high concentrations below the surface of the Earth due to natural decay of uranium and thorium. However, less information is available on the background levels of other isotopes such as 133Xe and 131mXe produced via spontaneous fission of either manmade or naturally occurring elements. The background concentrations of radioxenon in the subsurface are important to understand because these isotopes potentially can be used to confirm violations of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) during an On-Site Inspection (OSI). Recently, Pacific Northwest National Laboratory (PNNL) measured radioxenon concentrations from the subsurface at the Nevada Nuclear Security Site (NNSS—formerly known as the Nevada Test Site) to determine whether xenon isotope background levels could be detected from spontaneous fission of naturally occurring uranium or legacy 240Pu as a result of historic nuclear testing. In this paper, we discuss the results of those measurements and review the sources of xenon background that must be taken into account during OSI noble gas measurements.

  4. 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.

  5. Infrared Matrix-Isolation Study of New Noble-Gas Compounds

    NASA Astrophysics Data System (ADS)

    Zhu, Cheng; Räsänen, Markku; Khriachtchev, Leonid

    2016-06-01

    We identify new noble-gas compounds in solid matrices using IR spectroscopy. The compounds under study belong to two types: HNgY and YNgY' where Ng is a noble-gas atom and Y and Y' are electronegative fragments. The experimental assignments are supported by ab initio calculations at the MP2(full) and CCSD(T) levels of theory with the def2-TZVPPD basis set. We have prepared and characterized two new HNgY compounds (noble-gas hydrides): HKrCCCl in a Kr matrix and HXeCCCl in a Xe matrix.I The synthesis of these compounds includes two steps: UV photolysis of HCCCl in a noble-gas matrix to form the H + CCCl fragments and annealing of the matrix to mobilize H atoms and to promote the H + Ng + CCCl = HNgCCCl reaction. An interesting observation in the experiments on HXeCCCl in a Xe matrix is the temperature-induced transformation of the three H-Xe stretching bands. This observation is explained by temperature-induced changes of local matrix morphology around the embedded HXeCCCl molecule. In these experiments, we have also obtained the IR spectrum of the CCCl radical, which is produced by photodecomposition of HCCCl. We have identified three new YNgY' compounds (fluorinated noble-gas cyanides): FKrCN in a Kr matrix and FXeCN and FXeNC in a Xe matrix.II These molecule are formed by photolysis of FCN in a noble-gas matrix due to locality of this process. The amount of these molecules increases upon thermal mobilization of the F atoms in the photolyzed matrix featuring the F + Ng + CN reaction.

  6. Atomic Layer Deposition Route To Tailor Nanoalloys of Noble and Non-noble Metals.

    PubMed

    Ramachandran, Ranjith K; Dendooven, Jolien; Filez, Matthias; Galvita, Vladimir V; Poelman, Hilde; Solano, Eduardo; Minjauw, Matthias M; Devloo-Casier, Kilian; Fonda, Emiliano; Hermida-Merino, Daniel; Bras, Wim; Marin, Guy B; Detavernier, Christophe

    2016-09-27

    Since their early discovery, bimetallic nanoparticles have revolutionized various fields, including nanomagnetism and optics as well as heterogeneous catalysis. Knowledge buildup in the past decades has witnessed that the nanoparticle size and composition strongly impact the nanoparticle's properties and performance. Yet, conventional synthesis strategies lack proper control over the nanoparticle morphology and composition. Recently, atomically precise synthesis of bimetallic nanoparticles has been achieved by atomic layer deposition (ALD), alleviating particle size and compositional nonuniformities. However, this bimetal ALD strategy applies to noble metals only, a small niche within the extensive class of bimetallic alloys. We report an ALD-based approach for the tailored synthesis of bimetallic nanoparticles containing both noble and non-noble metals, here exemplified for Pt-In. First, a Pt/In2O3 bilayer is deposited by ALD, yielding precisely defined Pt-In nanoparticles after high-temperature H2 reduction. The nanoparticles' In content can be accurately controlled over the whole compositional range, and the particle size can be tuned from micrometers down to the nanometer scale. The size and compositional flexibility provided by this ALD-approach will trigger the fabrication of fully tailored bimetallic nanomaterials, including superior nanocatalysts.

  7. Collisional {sup 3}He and {sup 129}Xe Frequency Shifts in Rb-Noble-Gas Mixtures

    SciTech Connect

    Ma, Z. L.; Sorte, E. G.; Saam, B.

    2011-05-13

    The Fermi-contact interaction that characterizes collisional spin exchange of a noble gas with an alkali-metal vapor also gives rise to NMR and EPR frequency shifts of the noble-gas nucleus and the alkali-metal atom, respectively. We have measured the enhancement factor {kappa}{sub 0} that characterizes these shifts for Rb-{sup 129}Xe to be 493{+-}31, making use of the previously measured value of {kappa}{sub 0} for Rb-{sup 3}He. This result allows accurate {sup 129}Xe polarimetry with no need to reference a thermal-equilibrium NMR signal.

  8. 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

  9. Experimental evidence for high noble gas solubilities in silicate melts under mantle pressures

    NASA Astrophysics Data System (ADS)

    Schmidt, Burkhard C.; Keppler, Hans

    2002-02-01

    The solubilities of Ar and Xe in Fe-free synthetic haplogranitic and tholeiitic melts were experimentally determined in the pressure range of 1-11 GPa and at temperatures between 1500 and 2000°C. Experiments were performed in a piston cylinder apparatus (1-3 GPa) and in a multi-anvil apparatus (2-11 GPa). The noble gas concentrations in the quenched glasses were determined with electron microprobe. As a function of pressure, Ar solubility increases linearly up to about 4-5 GPa where it reaches about 4.0 and 0.8 wt% for the haplogranitic and tholeiitic melt, respectively. At higher pressure the amount of dissolved Ar remains constant, suggesting that some threshold concentration is reached. The Xe solubility in tholeiite melt exhibits a very similar pattern. It increases linearly up to about 6 GPa, where a threshold concentration of 0.8 wt% is reached. A further increase of pressure up to 11 GPa does not result in changes in Xe solubility. The leveling off in noble gas solubility at high pressures may imply that the interstitial sites in the melt structure, suitable for the accommodation of noble gas atoms, are fully occupied. Indeed, the experimental data can be successfully reproduced with the Langmuir isotherm, implying a solubility model in which the gas atoms occupy a certain population of interstitial sites. However, the data can be equally well described by a model assuming mixing of the noble gas atoms with the oxygen atoms of the silicate melt. From a thermodynamic point of view, the constant noble gas solubility at high pressures simply implies that the partial molar volumes of the respective noble gas in the fluid and in the melt are equal. Our results differ from those of Chamorro-Perez et al. [Earth Planet. Sci. Lett. 145 (1996) 97-107; Nature 393 (1998) 352-355] who reported an abrupt, order-of-magnitude drop of Ar solubility in silica and olivine melt at around 5 GPa, suggesting that melt densification results in an abrupt decrease of the hole size

  10. An isotope separator for small noble gas samples

    NASA Astrophysics Data System (ADS)

    Lehmann, B. E.; Rauber, D. F.; Thonnard, N.; Willis, R. D.

    1987-11-01

    A Wien filter isotope enrichment system has been combined with a small turbomolecular pump to form a closed isotope separator for small noble gas samples. Atoms which leave the exit aperture of the plasma discharge ion source without being ionized are circulated back into the source through a feedback line. The system can be operated for several hours in a closed mode to collect up to 50% of the total number of atoms of a selected isotope (e.g. 81Kr) out of a small gas sample of only 2 × 10 -3 cm 3 STP. Ions are implanted at 10 kV into an aluminized Kapton foil after a flight distance of 150 cm. A beam stabilization system centers the ion beam in two perpendicular directions onto a target aperture to maintain a high enrichment factor of at least 10 3 over extended periods of time. Calibration of the enrichment process is achieved by isotope dilution. The system is a key part of the sample processing for 81Kr and 85Kr analysis by laser resonance ionization spectroscopy for applications in isotope geophysics.

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

    NASA Astrophysics Data System (ADS)

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

    1981-10-01

    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.

  12. 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.

  13. Environmental effects on noble-gas hydrides: HXeBr, HXeCCH, and HXeH in noble-gas and molecular matrices

    SciTech Connect

    Tsuge, Masashi E-mail: leonid.khriachtchev@helsinki.fi; Lignell, Antti; Räsänen, Markku; Khriachtchev, Leonid E-mail: leonid.khriachtchev@helsinki.fi

    2013-11-28

    Noble-gas hydrides HNgY (Ng is a noble-gas atom and Y is an electronegative group) are sensitive probes of local environment due to their relatively weak bonding and large dipole moments. We experimentally studied HXeBr in Ar, Kr, and N{sub 2} matrices, HXeCCH in Ne and N{sub 2} matrices, and HXeH in an N{sub 2} matrix. These are the first observations of noble-gas hydrides in an N{sub 2} matrix. An N{sub 2} matrix strongly increases the H–Xe stretching frequency of HXeBr and HXeCCH with respect to a Ne matrix, which is presumably due to a strong interaction between the HNgY dipole moment and quadrupole moments of the surrounding lattice N{sub 2} molecules. The spectral shift of HXeBr in an N{sub 2} matrix is similar to that in a CO{sub 2} matrix, which is a rather unexpected result because the quadrupole moment of CO{sub 2} is about three times as large as that of N{sub 2}. The H–Xe stretching frequencies of HXeBr and HXeCCH in noble-gas matrices show a trend of ν(Ne) < ν(Xe) < ν(Kr) < ν(Ar), which is a non-monotonous function of the dielectric constants of the noble-gas solids. The MP2(full) calculations of HXeBr and HXeCCH with the polarizable continuum model as well as the CCSD(T) calculations of the HXeBr···Ng and HXeCCH···Ng (Ng = Ne, Ar, Kr, and Xe) complexes cannot fully explain the experimental observations. It is concluded that more sophisticated computational models should be used to describe these experimental findings.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Isotopic mass-dependence of noble gas diffusion coefficients inwater

    SciTech Connect

    Bourg, I.C.; Sposito, G.

    2007-06-25

    Noble gas isotopes are used extensively as tracers inhydrologic and paleoclimatic studies. These applications requireknowledge of the isotopic mass (m) dependence of noble gas diffusioncoefficients in water (D), which has not been measured but is estimatedusing experimental D-values for the major isotopes along with an untestedrelationship from kinetic theory, D prop m-0.5. We applied moleculardynamics methods to determine the mass dependence of D for four noblegases at 298 K, finding that D prop m-beta with beta<0.2, whichrefutes the kinetic theory model underlying all currentapplications.

  19. Computational phase diagrams of noble gas hydrates under pressure

    NASA Astrophysics Data System (ADS)

    Teeratchanan, Pattanasak; Hermann, Andreas

    2015-10-01

    We present results from a first-principles study on the stability of noble gas-water compounds in the pressure range 0-100 kbar. Filled-ice structures based on the host water networks ice-Ih, ice-Ic, ice-II, and C0 interacting with guest species He, Ne, and Ar are investigated, using density functional theory (DFT) with four different exchange-correlation functionals that include dispersion effects to various degrees: the non-local density-based optPBE-van der Waals (vdW) and rPW86-vdW2 functionals, the semi-empirical D2 atom pair correction, and the semi-local PBE functional. In the He-water system, the sequence of stable phases closely matches that seen in the hydrogen hydrates, a guest species of comparable size. In the Ne-water system, we predict a novel hydrate structure based on the C0 water network to be stable or at least competitive at relatively low pressure. In the Ar-water system, as expected, no filled-ice phases are stable; however, a partially occupied Ar-C0 hydrate structure is metastable with respect to the constituents. The ability of the different DFT functionals to describe the weak host-guest interactions is analysed and compared to coupled cluster results on gas phase systems.

  20. Computational phase diagrams of noble gas hydrates under pressure

    SciTech Connect

    Teeratchanan, Pattanasak Hermann, Andreas

    2015-10-21

    We present results from a first-principles study on the stability of noble gas-water compounds in the pressure range 0-100 kbar. Filled-ice structures based on the host water networks ice-I{sub h}, ice-I{sub c}, ice-II, and C{sub 0} interacting with guest species He, Ne, and Ar are investigated, using density functional theory (DFT) with four different exchange-correlation functionals that include dispersion effects to various degrees: the non-local density-based optPBE-van der Waals (vdW) and rPW86-vdW2 functionals, the semi-empirical D2 atom pair correction, and the semi-local PBE functional. In the He-water system, the sequence of stable phases closely matches that seen in the hydrogen hydrates, a guest species of comparable size. In the Ne-water system, we predict a novel hydrate structure based on the C{sub 0} water network to be stable or at least competitive at relatively low pressure. In the Ar-water system, as expected, no filled-ice phases are stable; however, a partially occupied Ar-C{sub 0} hydrate structure is metastable with respect to the constituents. The ability of the different DFT functionals to describe the weak host-guest interactions is analysed and compared to coupled cluster results on gas phase systems.

  1. An Air Noble Gas Component in the Mantle

    NASA Astrophysics Data System (ADS)

    Sarda, P.

    2005-12-01

    Noble gas geochemistry has for long attempted to recover isotopic signatures of mantle components through analyses of basalt glass or xenoliths, but this quest has been plagued by the occurrence of a conspicuous air component, which appears to have both the isotopic and elemental composition of air (except for helium). It is classically considered to be air added to samples close to the surface, in a poorly understood process called "contamination", due to the interaction of rocks and melts with air or water on emplacement. Focusing on Mid-Ocean Ridge Basalts (and Ocean Island Basalts), gases are mostly borne by vesicles and a number of puzzling observations can be made: - vesicles appear to be heterogeneous at the scale of a centimeter, as shown by stepwise crushing experiments, some vesicles having air, some having mantle gases, some having mixtures of both, - vesicles appear over-pressured (P > 1 bar) in fresh samples, as shown by highly vesiculous samples such as Popping Rocks, - the air component appears to be borne by the largest vesicles, as it is recovered in the first steps of stepwise crushing analyses, - larger samples seem to have more of the air component than smaller ones, - in Popping Rocks, the air component borne by the largest vesicles is overwhelming, - the isotopic composition of Pb-Sr-Nd in Popping Rocks was interpreted as indicating a recycled component (related to the HIMU and EM1 mantle end-members). The air noble gas component was suggested recently to be not seawater, but modern air located in fractures of the glass, which should have opened on cooling and resealed immediately [1]. This model faces some difficulties, such as keeping pressure high in the vesicles. I suggest another interpretation, namely that a large part of the air noble gases in oceanic basalts is recycled in origin [2]. It would have been carried down into the mantle at subduction zones, even if most (typically 90%) of the air noble gases in the slab returns to the

  2. 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.

  3. Disruption Mitigation With High-Pressure Noble Gas Injection

    NASA Astrophysics Data System (ADS)

    Whyte, D. G.

    2002-11-01

    As tokamak fusion research approaches the realization of burning plasmas, we must develop methods to control the damage caused by disruptions. In-vessel components are damaged in three principal ways: divertor surface melting/ablation by plasma heating, mechanical stresses caused by poloidal halo currents, and amplification of runaway relativistic electrons that eventually are lost into the wall. Experiments on the DIII-D tokamak have demonstrated a technique that mitigates the three disruption damage effects. A high-pressure jet of a noble gas (neon or argon) is injected into the plasma. The jet penetrates to the central plasma at the gas sound speed (300-500 m/s), seemingly due to the high ram pressure of the gas jet, and increases the atom/ion content in the plasma volume by a factor of 50 in several milliseconds. As a result, the plasma energy is dissipated uniformly by UV radiation over the entire wall, and the heat conducted to the divertor is reduced from 20%-40% of the initial plasma energy for an unmitigated disruption to <4%. The radiative collapse initiates a rapid current quench with the plasma remaining centered in the vessel, effectively reducing halo currents. Runaway electrons are controlled by the large density of bound electrons in the plasma volume, despite the large parallel electric field. Initial results on real-time disruption detection are encouraging, with the plasma control system triggering the neon gas jet injection into the unstable plasma and mitigating the disruption damage. Physical models developed to understand the DIII-D results describe the thermal/ionization balance and the evolution of halo currents well. Extrapolation to burning plasma experiments shows that thermal and halo current mitigation is possible and that runaway electrons can be suppressed.

  4. Detection of gas atoms with carbon nanotubes

    PubMed Central

    Arash, B.; Wang, Q.

    2013-01-01

    Owning to their unparalleled sensitivity resolution, nanomechanical resonators have excellent capabilities in design of nano-sensors for gas detection. The current challenge is to develop new designs of the resonators for differentiating distinct gas atoms with a recognizably high sensitivity. In this work, the characteristics of impulse wave propagation in carbon nanotube-based sensors are investigated using molecular dynamics simulations to provide a new method for detection of noble gases. A sensitivity index based on wave velocity shifts in a single-walled carbon nanotube, induced by surrounding gas atoms, is defined to explore the efficiency of the nano-sensor. The simulation results indicate that the nano-sensor is able to differentiate distinct noble gases at the same environmental temperature and pressure. The inertia and the strengthening effects by the gases on wave characteristics of carbon nanotubes are particularly discussed, and a continuum mechanics shell model is developed to interpret the effects.

  5. The Origin of Noble Gas Isotopic Heterogeneity in Icelandic Basalts

    NASA Technical Reports Server (NTRS)

    Dixon, E. T.; Honda, M.; McDougall, I.

    2001-01-01

    Two models for generation of heterogeneous He, Ne and Ar isotopic ratios in Icelandic basalts are evaluated using a mixing model and the observed noble gas elemental ratios in Icelandic basalts,Ocean island Basalt (OIBs) and Mid-Ocean Ridge Basalt (MORBs). Additional information is contained in the original extended abstract.

  6. The Origin of Noble Gas Isotopic Heterogeneity in Icelandic Basalts

    NASA Technical Reports Server (NTRS)

    Dixon, E. T.; Honda, M.; McDougall, I.

    2001-01-01

    Two models for generation of heterogeneous He, Ne and Ar isotopic ratios in Icelandic basalts are evaluated using a mixing model and the observed noble gas elemental ratios in Icelandic basalts,Ocean island Basalt (OIBs) and Mid-Ocean Ridge Basalt (MORBs). Additional information is contained in the original extended abstract.

  7. Noble Gas Polarimetry Using Rb EPR Frequency Shifts

    NASA Astrophysics Data System (ADS)

    Ma, Z. L.; Jeong, K.; Houghtby, E.; Paskvan, T.; Limes, M. E.; Saam, B.

    2014-05-01

    EPR frequency shifts of optically polarized alkali-metal atoms can be exploited for polarimetry of noble-gas nuclei polarized by spin-exchange optical pumping. Our group recently measured the enhancement factor κ0 = 493 for Rb-129Xe, which characterizes the electron wave-function overlap during collisions and is crucial to the calibration of the frequency-shift for 129Xe polarimetry. This type of polarimetry is useful in several applications involving optically polarized 129Xe; our particular motivation is an in situ measurement of absolute 129Xe polarization within the optical pumping cell of a flow-through 129Xe polarizer. This application has some particular challenges, and we have initially observed some unexpected shifts in the 87Rb EPR frequency measurement on board the polarizer. In effort to disentangle these apparent systematic effects, we have constructed a separate experiment to characterize Rb EPR shifts for both 3He and 129Xe in sealed cells. We present results and analysis of these experiments and discuss implications for using this method in flow-through polarizers. NSF PHY-0855482

  8. 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

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

    PubMed

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

    1998-10-26

    NMR images of laser polarized 3He gas were obtained at 21 G using a simple, homebuilt instrument. At such low fields magnetic resonance imaging (MRI) of thermally polarized samples (e.g., water) is not practical. Low-field noble gas MRI has novel scientific, engineering, and medical applications. Examples include portable systems for diagnosis of lung disease, as well as imaging of voids in porous media and within metallic systems.

  10. Low-field MRI of laser polarized noble gas

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    NMR images of laser polarized 3He gas were obtained at 21 G using a simple, homebuilt instrument. At such low fields magnetic resonance imaging (MRI) of thermally polarized samples (e.g., water) is not practical. Low-field noble gas MRI has novel scientific, engineering, and medical applications. Examples include portable systems for diagnosis of lung disease, as well as imaging of voids in porous media and within metallic systems.

  11. Evaluation of interatomic potentials for noble gas atoms from rainbow scattering under axial channeling at Ag(1 1 1) surface by computer simulations based on binary collision approximation

    NASA Astrophysics Data System (ADS)

    Takeuchi, Wataru

    2016-01-01

    The rainbow angles corresponding to pronounced peaks in the angular distributions of scattered projectiles with small angle, attributed to rainbow scattering (RS), under axial surface channeling conditions are strongly dependent on the interatomic potentials between projectiles and target atoms. The dependence of rainbow angles on normal energy of projectile energy to the target surface that has been experimentally obtained by Schüller and Winter (SW) (2007) for RS of He, Ne and Ar atoms from a Ag(1 1 1) surface with projectile energies of 3-60 keV was evaluated by the three-dimensional computer simulations using the ACOCT code based on the binary collision approximation with interatomic pair potentials. Consequently, the ACOCT results employing the Moliere pair potential with screening length correction close to adjustable one of O'Connor and Biersack (OB) formula are almost in agreement with the experimental ones, being self-consistent with the SW's ones analyzed by computer simulations of classical trajectory calculations as RS from corrugated equipotential planes based on continuum potentials including the Moliere pair potential with screening length correction of the OB formula.

  12. Reactions of laser-ablated U atoms with HF: infrared spectra and quantum chemical calculations of HUF, UH, and UF in noble gas solids.

    PubMed

    Vent-Schmidt, Thomas; Andrews, Lester; Riedel, Sebastian

    2015-03-19

    Reactions of laser-ablated U atoms with HF produce HUF as the major product and UH and UF as minor products, which are identified from their argon and neon matrix infrared spectra. Our assignment of HUF is confirmed by the observation of DUF and close agreement with observed and calculated vibrational frequencies and deuterium shifts in the vibrational frequencies. Our previous observation of the UH diatomic molecule from argon matrix experiments with H2, HD, and D2 as reagents is confirmed through its present observation with HF and DF, and with recent higher level quantum chemical calculations. The HF reaction provides a lower concentration of F in the system and thus simplifies the fluorine chemistry relative to similar U atom reactions with F2, and the new matrix identification of UF here is consistent with recent high level calculations on UF. In addition, we find evidence for the higher oxidation state secondary reaction products UHF2, UHF3, and UH2F2.

  13. Noble Gas Tracing of Fluid Transport in Shale Reservoirs

    NASA Astrophysics Data System (ADS)

    Heath, J. E.; Gardner, W. P.; Kuhlman, K. L.; Robinson, D. G.; Bauer, S. J.

    2014-12-01

    We investigate fluid transport mechanisms in a shale reservoir using natural noble gas tracers. Noble gas tracing is promising due to sensitivity of transport to: pore structure and sizes; phase partitioning between groundwater and liquid and gaseous hydrocarbons; and deformation from hydraulic fracturing and creation of surface area. A time-series of over thirty wellhead fluid samples were collected from two hydraulically-fractured wells with different oil-to-gas ratios, along with production data (i.e., flowrate and pressure). Tracer and production data sets can be combined to infer production flow regimes, to estimate reservoir transport parameters, and to improve forecasts of production decline. 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 Security Administration under contract DE-AC04-94AL85000.

  14. On the vibrational linear and nonlinear optical properties of compounds involving noble gas atoms: HXeOXeH, HXeOXeF, and FXeOXeF.

    PubMed

    Avramopoulos, Aggelos; Reis, Heribert; Luis, Josep M; Papadopoulos, Manthos G

    2013-06-30

    The vibrational (hyper)polarizabilities of some selected Xe derivatives are studied in the context of Bishop-Kirtman perturbation theory (BKPT) and numerical finite field methodology. It was found that for this set of rare gas compounds, the static vibrational properties are quite large, in comparison to the corresponding electronic ones, especially those of the second hyperpolarizability. This also holds for the dc-Pockels β(-ω;ω,0), Kerr γ(-ω;ω,0,0) and electric field second harmonic generation γ (-2ω;ω,ω,0) effects, although the computed nuclear relaxation (nr) vibrational contributions are smaller in magnitude than the static ones. HXeOXeH was used to study the effects of electron correlation, basis set, and geometry. Geometry effects were found to lead to noticeable changes of the vibrational and electronic second hyperpolarizability. A limited study of the effect of Xe insertion to the nr vibrational properties is also reported. Assessment of the results revealed that Xe insertion has a remarkable effect on the nr (hyper)polarizabilities. In terms of the BKPT, this is associated with a remarkable increase of the electrical and mechanical anharmonicity terms. The latter is consistent with the anharmonic character of several vibrational modes reported for rare gas compounds.

  15. Solid H2 versus solid noble-gas environment: Influence on photoinduced hydrogen-atom transfer in matrix-isolated 4(3H)-pyrimidinone

    NASA Astrophysics Data System (ADS)

    Lapinski, Leszek; Nowak, Maciej J.; Rostkowska, Hanna

    2017-03-01

    UV-induced transformations have been studied for 4(3H)-pyrimidinone monomers isolated in low-temperature Ar, Ne, n-D2, and n-H2 matrices. The observed photochemical behavior of the compound drastically depended on the solid matrix environment. For 4(3H)-pyrimidinone isolated in solid Ar, the UV-induced phototautomeric transformation was clearly the dominating process, leading to a nearly quantitative conversion of the oxo reactant into the hydroxy product. For solid Ne environment, the oxo → hydroxy transformation was still the major photoprocess, but yielding less of the hydroxy product (ca. 64% of the yield in solid Ar). For 4(3H)-pyrimidinone isolated in solid n-H2, the oxo → hydroxy phototautomeric conversion did not occur (or occurred at a very tiny scale). Also for deuterated 4(3D)-pyrimidinone isolated in solid hydrogen, the analogous oxo → deuteroxy phototransformation was not observed. Finally, for the compound trapped in solid n-D2, the oxo → hydroxy phototautomerism clearly occurred, but the yield of the hydroxy tautomer was small (ca. 18% of the yield in solid Ar). Apart from hydrogen-atom-transfer processes, two other phototransformations: generation of open-ring conjugated ketene and valence Dewar isomer were observed for the compound isolated in Ar, Ne, n-D2, and n-H2 matrices.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  18. Nuclear monitoring by nonradioactive noble gas sampling and analysis

    SciTech Connect

    Fearey, B.L.; Nakhleh, C.W.; Stanbro, W.D.

    1997-10-01

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The perceived importance of measuring the xenon and krypton isotopics of nuclear activities has increased substantially in recent years. We have performed a systems analysis and theoretical simulation of the production, atmospheric dispersion, and isotopic abundances of noble-gas fission products, addressing several questions of interest, including: the relative isotopic variation as a function of nuclear fuel composition, reactor operational history, reactor type, distance from stack, and ambient meteorological conditions. Of particular importance in this analysis was the question of back-calculating process parameters of interest given noble-gas isotopic data. An analysis of the effect of measurement uncertainties was also performed. The results of these analyses indicate that this monitoring concept should be experimentally feasible.

  19. Noble Gas Excimer Detectors for Security and Safeguards Applications

    SciTech Connect

    Hynes, Michael V.; Lanza, Richard; Chandra, Rico; Davatz, Giovanna

    2011-12-13

    Noble gas excimer detectors are a technology that is common in particle physics research and less common in applications for security and international safeguards. These detectors offer the capability to detect gammas with an energy resolution similar to NaI and to detect neutrons with good energy resolution as well. Depending on the noble gas selected and whether or not it is in a gaseous or liquid state, the sensitivity to gammas and neutrons can be tuned according to the needs of the application. All of this flexibility can be available at a significant cost saving over alternative technologies. This paper will review this detector technology and its applicability to security and safeguards.

  20. Prediction of a neutral noble gas compound in the triplet state.

    PubMed

    Manna, Debashree; Ghosh, Ayan; Ghanty, Tapan K

    2015-05-26

    Discovery of the HArF molecule associated with H-Ar covalent bonding [Nature, 2000, 406, 874-876] has revolutionized the field of noble gas chemistry. In general, this class of noble gas compound involving conventional chemical bonds exists as closed-shell species in a singlet electronic state. For the first time, in a bid to predict neutral noble gas chemical compounds in their triplet electronic state, we have carried out a systematic investigation of xenon inserted FN and FP species by using quantum chemical calculations with density functional theory and various post-Hartree-Fock-based correlated methods, including the multireference configuration interaction technique. The FXeP and FXeN species are predicted to be stable by all the computational methods employed in the present work, such as density functional theory (DFT), second-order Møller-Plesset perturbation theory (MP2), coupled-cluster theory (CCSD(T)), and multireference configuration interaction (MRCI). For the purpose of comparison we have also included the Kr-inserted compounds of FN and FP species. Geometrical parameters, dissociation energies, transition-state barrier heights, atomic charge distributions, vibrational frequency data, and atoms-in-molecules properties clearly indicate that it is possible to experimentally realize the most stable state of FXeP and FXeN molecules, which is triplet in nature, through the matrix isolation technique under cryogenic conditions.

  1. Comparison of the bonding between ML(+) and ML2(+) (M = metal, L = noble gas)

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.

    1990-01-01

    Ab initio calculations are reported of the spectroscopic constants for the low-lying states of the molecular ions ML2(+), where M = Li, Na, Mg, V, Fe, Co, Ni and Cu, and where L is usually Ar. Comparison with existing analogous calculations on the ML(+) ions shows how the bonding and binding energy change with the addition of a second noble gas atom. The second binding energy is predicted to be essentially the same as the first for the Li, Na, Mg, and V ions, but larger for the Fe, Co, Ni and Cu ions. The binding energies of the transition metal noble gas ions are not accurately predicted at the SCF level, because correlation is required to describe their M(0)Ln(+) character. All trends can be explained in terms of promotion and hybridization on the metal ion.

  2. Comparison of the bonding between ML(+) and ML2(+) (M = metal, L = noble gas)

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.

    1990-01-01

    Ab initio calculations are reported of the spectroscopic constants for the low-lying states of the molecular ions ML2(+), where M = Li, Na, Mg, V, Fe, Co, Ni and Cu, and where L is usually Ar. Comparison with existing analogous calculations on the ML(+) ions shows how the bonding and binding energy change with the addition of a second noble gas atom. The second binding energy is predicted to be essentially the same as the first for the Li, Na, Mg, and V ions, but larger for the Fe, Co, Ni and Cu ions. The binding energies of the transition metal noble gas ions are not accurately predicted at the SCF level, because correlation is required to describe their M(0)Ln(+) character. All trends can be explained in terms of promotion and hybridization on the metal ion.

  3. Possible solar noble-gas component in Hawaiian basalts

    USGS Publications Warehouse

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

    1991-01-01

    THE noble-gas elemental and isotopic composition in the Earth is significantly different from that of the present atmosphere, and provides an important clue to the origin and history of the Earth and its atmosphere. Possible candidates for the noble-gas composition of the primordial Earth include a solar-like component, a planetary-like component (as observed in primitive meteorites) and a component similar in composition to the present atmosphere. In an attempt to identify the contributions of such components, we have measured isotope ratios of helium and neon in fresh basaltic glasses dredged from Loihi seamount and the East Rift Zone of Kilauea1-3. We find a systematic enrichment in 20Ne and 21Ne relative to 22Ne, compared with atmospheric neon. The helium and neon isotope signatures observed in our samples can be explained by mixing of solar, present atmospheric, radiogenic and nucleogenic components. These data suggest that the noble-gas isotopic composition of the mantle source of the Hawaiian plume is different from that of the present atmosphere, and that it includes a significant solar-like component. We infer that this component was acquired during the formation of the Earth.

  4. Hypervalent versus nonhypervalent carbon in noble-gas complexes.

    PubMed

    Pierrefixe, Simon C A H; Poater, Jordi; Im, Chan; Bickelhaupt, F Matthias

    2008-01-01

    Silicon in [Cl--SiH(3)--Cl](-) is hypervalent, whereas carbon in [Cl--CH(3)--Cl](-) is not. We have recently shown how this can be understood in terms of the ball-in-a-box model, according to which silicon fits perfectly into the box that is constituted by the five substituents, whereas carbon is too small and, in a sense, "drops to the bottom" of the box. But how does carbon acquire hypervalency in the isostructural and isoelectronic noble gas (Ng)/methyl cation complexes [Ng--CH(3)--Ng](+) (Ng=He and Ne), which feature a delocalized D(3h)-symmetric structure with two equivalent C--Ng bonds? From Ng=Ar onwards, the [Ng--CH(3)--Ng](+) complex again acquires a propensity to localize one of its axial C--Ng bonds and to largely break the other one, and this propensity increases in the order Ng=Aratom in [Ng--CH(3)--Ng](+) can no longer be considered as a ball in a box of the five substituents.

  5. 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.

  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

  7. 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.

  8. Noble Gas Signatures in Athabasca Glacier - Tracing Glacial Meltwater Sources

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    We present a noble gas study in glacial meltwater (GMW) from the Athabasca Glacier (AG) in the Columbia Icefield, Canada. It constrains the relative contributions of GMW sources, water residence times, and spatial locations where the GMW originates in the alpine glacier. 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) which allows for estimation of the altitude at which GMW originated. In addition, crustal He accumulates in water over time, allowing for estimation of water residence times. Water samples were collected in the morning on selected dates in May and July 2011 at two locations about 200 m apart near the terminus area at altitudes between 2000 m and 2100 m. Eight samples were collected in six different days. Results show that the major source of subglacial meltwater is ASW rather than old, compressed glacial ice, which has a distinct noble gas signature not seen in our samples. Given that, GMW samples from the AG do deviate to a certain extent from the ASW values corresponding to measured water temperature and altitude at collection points. Two patterns are observed in the concentrations of the AG samples. The first one presents a relative Ar enrichment with respect to Ne, Kr, and Xe, first observed in high-altitude springs in the Galápagos Islands (Warrier et al., 2012). The second one displays a mass-dependent pattern, first observed in Michigan rainwater (Warrier et al., 2013). A preliminary Xe analysis indicates equilibration altitudes between 2500 m and 3400 m, values compatible with local topography. Samples present He excess of 4% to 91%, and suggest an average residence time of ~400 yrs. References:Warrier, R. B., Castro, M. C., and Hall, C. M. (2012), Recharge and source-water insights from the Galapagos Islands using noble gases and stable isotopes, Water Resour. Res., 48, W03508, doi:10.1029/2011WR010954. Warrier, R. B., Castro

  9. 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.

  10. Atomistic-Scale Simulations of Defect Formation in Graphene under Noble Gas Ion Irradiation.

    PubMed

    Yoon, Kichul; Rahnamoun, Ali; Swett, Jacob L; Iberi, Vighter; Cullen, David A; Vlassiouk, Ivan V; Belianinov, Alex; Jesse, Stephen; Sang, Xiahan; Ovchinnikova, Olga S; Rondinone, Adam J; Unocic, Raymond R; van Duin, Adri C T

    2016-09-27

    Despite the frequent use of noble gas ion irradiation of graphene, the atomistic-scale details, including the effects of dose, energy, and ion bombardment species on defect formation, and the associated dynamic processes involved in the irradiations and subsequent relaxation have not yet been thoroughly studied. Here, we simulated the irradiation of graphene with noble gas ions and the subsequent effects of annealing. Lattice defects, including nanopores, were generated after the annealing of the irradiated graphene, which was the result of structural relaxation that allowed the vacancy-type defects to coalesce into a larger defect. Larger nanopores were generated by irradiation with a series of heavier noble gas ions, due to a larger collision cross section that led to more detrimental effects in the graphene, and by a higher ion dose that increased the chance of displacing the carbon atoms from graphene. Overall trends in the evolution of defects with respect to a dose, as well as the defect characteristics, were in good agreement with experimental results. Additionally, the statistics in the defect types generated by different irradiating ions suggested that the most frequently observed defect types were Stone-Thrower-Wales (STW) defects for He(+) irradiation and monovacancy (MV) defects for all other ion irradiations.

  11. Atomistic-scale simulations of defect formation in graphene under noble gas ion irradiation

    SciTech Connect

    Yoon, Kichul; Rahnamoun, Ali; Swett, Jacob L.; Iberi, Vighter; Cullen, David A.; Vlassiouk, Ivan V.; Belianinov, Alex; Jesse, Stephen; Sang, Xiahan; Ovchinnikova, Olga S.; Rondinone, Adam Justin; Unocic, Raymond R.; van Duin, Adri C. T.

    2016-08-17

    Despite the frequent use of noble gas ion irradiation of graphene, the atomistic-scale details, including the effects of dose, energy, and ion bombardment species on defect formation, and the associated dynamic processes involved in the irradiations and subsequent relaxation have not yet been thoroughly studied. Here, we simulated the irradiation of graphene with noble gas ions and the subsequent effects of annealing. Lattice defects, including nanopores, were generated after the annealing of the irradiated graphene, which was the result of structural relaxation that allowed the vacancy-type defects to coalesce into a larger defect. Larger nanopores were generated by irradiation with a series of heavier noble gas ions, due to a larger collision cross section that led to more detrimental effects in the graphene, and by a higher ion dose that increased the chance of displacing the carbon atoms from graphene. Overall trends in the evolution of defects with respect to a dose, as well as the defect characteristics, were in good agreement with experimental results. In addition, the statistics in the defect types generated by different irradiating ions suggested that the most frequently observed defect types were Stone-Thrower-Wales (STW) defects for He+ irradiation and monovacancy (MV) defects for all other ion irradiations.

  12. Atomistic-scale simulations of defect formation in graphene under noble gas ion irradiation

    DOE PAGES

    Yoon, Kichul; Rahnamoun, Ali; Swett, Jacob L.; ...

    2016-08-17

    Despite the frequent use of noble gas ion irradiation of graphene, the atomistic-scale details, including the effects of dose, energy, and ion bombardment species on defect formation, and the associated dynamic processes involved in the irradiations and subsequent relaxation have not yet been thoroughly studied. Here, we simulated the irradiation of graphene with noble gas ions and the subsequent effects of annealing. Lattice defects, including nanopores, were generated after the annealing of the irradiated graphene, which was the result of structural relaxation that allowed the vacancy-type defects to coalesce into a larger defect. Larger nanopores were generated by irradiation withmore » a series of heavier noble gas ions, due to a larger collision cross section that led to more detrimental effects in the graphene, and by a higher ion dose that increased the chance of displacing the carbon atoms from graphene. Overall trends in the evolution of defects with respect to a dose, as well as the defect characteristics, were in good agreement with experimental results. In addition, the statistics in the defect types generated by different irradiating ions suggested that the most frequently observed defect types were Stone-Thrower-Wales (STW) defects for He+ irradiation and monovacancy (MV) defects for all other ion irradiations.« less

  13. Atomistic-scale simulations of defect formation in graphene under noble gas ion irradiation

    SciTech Connect

    Yoon, Kichul; Rahnamoun, Ali; Swett, Jacob L.; Iberi, Vighter; Cullen, David A.; Vlassiouk, Ivan V.; Belianinov, Alex; Jesse, Stephen; Sang, Xiahan; Ovchinnikova, Olga S.; Rondinone, Adam Justin; Unocic, Raymond R.; van Duin, Adri C. T.

    2016-08-17

    Despite the frequent use of noble gas ion irradiation of graphene, the atomistic-scale details, including the effects of dose, energy, and ion bombardment species on defect formation, and the associated dynamic processes involved in the irradiations and subsequent relaxation have not yet been thoroughly studied. Here, we simulated the irradiation of graphene with noble gas ions and the subsequent effects of annealing. Lattice defects, including nanopores, were generated after the annealing of the irradiated graphene, which was the result of structural relaxation that allowed the vacancy-type defects to coalesce into a larger defect. Larger nanopores were generated by irradiation with a series of heavier noble gas ions, due to a larger collision cross section that led to more detrimental effects in the graphene, and by a higher ion dose that increased the chance of displacing the carbon atoms from graphene. Overall trends in the evolution of defects with respect to a dose, as well as the defect characteristics, were in good agreement with experimental results. In addition, the statistics in the defect types generated by different irradiating ions suggested that the most frequently observed defect types were Stone-Thrower-Wales (STW) defects for He+ irradiation and monovacancy (MV) defects for all other ion irradiations.

  14. Potential Energy Curves and Associated Line Shape of Alkali-Metal and Noble-Gas Interactions

    DTIC Science & Technology

    2014-10-20

    Potential Energy Curves and Associated Line Shape of Alkali - Metal and Noble-Gas Interactions DISSERTATION Larry Aaron Blank, Civ AFIT-ENP-DS-14-D-51...OF ALKALI - METAL AND NOBLE-GAS INTERACTIONS DISSERTATION Presented to the Faculty Graduate School of Engineering and Management Air Force Institute of...ENP-DS-14-D-51 POTENTIAL ENERGY CURVES AND ASSOCIATED LINE SHAPE OF ALKALI - METAL AND NOBLE-GAS INTERACTIONS Larry Aaron Blank, B.S., M.S. Civ Approved

  15. A Simple Model for Fine Structure Transitions in Alkali-Metal Noble-Gas Collisions

    DTIC Science & Technology

    2015-03-01

    A SIMPLE MODEL FOR FINE STRUCTURE TRANSITIONS IN ALKALI - METAL NOBLE-GAS COLLISIONS THESIS Joseph A. Cardoza, Captain, USAF AFIT-ENP-MS-15-M-079... ALKALI - METAL NOBLE-GAS COLLISIONS THESIS Presented to the Faculty Department of Engineering Physics Graduate School of Engineering and Management Air...AFIT-ENP-MS-15-M-079 A SIMPLE MODEL FOR FINE STRUCTURE TRANSITIONS IN ALKALI - METAL NOBLE-GAS COLLISIONS Joseph A. Cardoza, BS Captain, USAF Committee

  16. Mechanism of the radiation-induced transformations of fluoroform in solid noble gas matrixes

    NASA Astrophysics Data System (ADS)

    Sosulin, Ilya S.; Shiryaeva, Ekaterina S.; Feldman, Vladimir I.

    2017-09-01

    The X-ray induced transformations in the CHF3/Ng systems (Ng=Ne, Ar, Kr or Xe) at 6 K were studied by FTIR spectroscopy. The radiation-induced decomposition of CHF3 was found to be rather inefficient in solid xenon with low ionization energy, which suggests primary significance of the positive hole transfer from matrix to the fluoroform molecule. CF3•, :CF2, CHF2• and CF4 were identified as the products of low-temperature radiolysis in all the noble gas matrixes. In addition, the anionic complex HF ⋯ CF2- was detected in Ne and Ar matrixes. The radiolysis also resulted in formation of noble gas compounds (HArF in argon, HKrF in krypton, and XeF2 in xenon). While XeF2 and HArF were essentially formed directly after irradiation (presumably due to reactions of 'hot' fluorine atoms), HKrF mainly resulted from annealing of irradiated samples below 20 K due to thermally induced mobility of trapped fluorine atoms. In both krypton and xenon matrixes, the thermally induced reactions of F atoms occur at lower temperatures than those of H atoms, while the opposite situation is observed in argon. The mechanisms of the radiation-induced processes and their implications are discussed.

  17. Bonding of multiple noble-gas atoms to CUO in solid neon: CUO(Ng)n (Ng=Ar, Kr, Xe; n=1, 2, 3, 4) complexes and the singlet-triplet crossover point.

    PubMed

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

    2003-10-06

    Laser-ablated U atoms co-deposited with CO in excess neon produce the novel CUO molecule, which forms distinct Ng complexes (Ng=Ar, Kr, Xe) with the heavier noble gases. The CUO(Ng) complexes are identified through CO isotopic and Ng reagent substitution and comparison to results of DFT frequency calculations. The U[bond]C and U[bond]O stretching frequencies of CUO(Ng) complexes are slightly red-shifted from neon matrix (1)Sigma(+) CUO values, which indicates a (1)A' ground state for the CUO(Ng) complexes. The CUO(Ng)(2) complexes in excess neon are likewise singlet molecules. However, the CUO(Ng)(3) and CUO(Ng)(4) complexes exhibit very different stretching frequencies and isotopic behaviors that are similar to those of CUO(Ar)(n) in a pure argon matrix, which has a (3)A" ground state based on DFT vibrational frequency calculations. This work suggests a coordination sphere model in which CUO in solid neon is initially solvated by four or more Ne atoms. Up to four heavier Ng atoms successively displace the Ne atoms leading ultimately to CUO(Ng)(4) complexes. The major changes in the CUO stretching frequencies from CUO(Ng)(2) to CUO(Ng)(3) provides evidence for the crossover from a singlet ground state to a triplet ground state.

  18. 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

  19. Solubility controlled noble gas fractionation during magmatic degassing: Implications for noble gas compositions of primary melts of OIB and MORB

    NASA Astrophysics Data System (ADS)

    Yamamoto, Junji; Burnard, Pete G.

    2005-02-01

    Noble gas abundances in basaltic glasses from ocean islands (OIBs) are generally lower than those of mid-oceanic ridge basalts (MORBs), contrary to most geodynamic models which usually require that the source of OIBs is less degassed (resulting in higher primordial noble gas abundances) and more trace element enriched (resulting in higher radiogenic noble gas abundances) than the MORB source. Therefore, noble gas abundances in OIBs are often thought to have been reduced by extensive gas loss from the magma before eruption. The extent of magmatic degassing can be tested as it will cause characteristic changes in the composition of the volatiles; notably the 4He/ 40Ar* ratio (where 40Ar* is 40Ar corrected for atmospheric contamination) will increase in residual volatiles due to the higher solubility of He relative to Ar. The degree of He-Ar fractionation for a given fraction of gas loss depends on the ratio of the solubilities, S He/S Ar, which is sensitive to (among other things) the CO 2 and H 2O content of the basalt at the time of degassing. From a global database of OIB and MORB glasses, we show that 4He/ 40Ar* ratios of MORB glasses are broadly consistent with degassing of a magma with an initial 40Ar of ≈1.5 × 10 -5 ccSTP/g, i.e., similar to that of the "popping rock." However, OIB glasses generally have lower 40Ar* concentration for a given 4He/ 40Ar*. While this would appear to require lower 40Ar* abundances in the undegassed OIB magmas, the higher volatile contents of OIBs will reduce S He/S Ar (relative to MORBs) during degassing. By modeling S He/S Ar in OIBs, it is possible to show that extensive degassing of OIBs can occur without dramatically increasing the 4He/ 40Ar* ratio. We show that undegassed 40Ar concentrations of OIB magmas were probably similar to those of MORBs.

  20. Mechanical response of noble gas films to an oscillating substrate

    NASA Astrophysics Data System (ADS)

    Kobayashi, Hajime; Taniguchi, Junko; Suzuki, Masaru; Miura, Kouji; Arakawa, Ichiro

    2012-12-01

    We carried out quartz-crystal microbalance (QCM) experiments for Xe films adsorbed on an exfoliated single-crystalline graphite substrate (Xe/Gr) and Kr 1ms adsorbed on a synthetic mica substrate (Kr/mica) around LN2 temperature. For Xe/Gr, it was found that the resonance frequency decreases greatly around the first layer completion, while it does not decrease at low coverages. The observed behavior is similar to that of Kr films on a graphite substrate (Kr/Gr). This demonstrates that the layer completion strongly affects the sliding motion of noble gas films on graphite.

  1. The Noble-Abel Stiffened-Gas equation of state

    NASA Astrophysics Data System (ADS)

    Le Métayer, Olivier; Saurel, Richard

    2016-04-01

    Hyperbolic two-phase flow models have shown excellent ability for the resolution of a wide range of applications ranging from interfacial flows to fluid mixtures with several velocities. These models account for waves propagation (acoustic and convective) and consist in hyperbolic systems of partial differential equations. In this context, each phase is compressible and needs an appropriate convex equation of state (EOS). The EOS must be simple enough for intensive computations as well as boundary conditions treatment. It must also be accurate, this being challenging with respect to simplicity. In the present approach, each fluid is governed by a novel EOS named "Noble Abel stiffened gas," this formulation being a significant improvement of the popular "Stiffened Gas (SG)" EOS. It is a combination of the so-called "Noble-Abel" and "stiffened gas" equations of state that adds repulsive effects to the SG formulation. The determination of the various thermodynamic functions and associated coefficients is the aim of this article. We first use thermodynamic considerations to determine the different state functions such as the specific internal energy, enthalpy, and entropy. Then we propose to determine the associated coefficients for a liquid in the presence of its vapor. The EOS parameters are determined from experimental saturation curves. Some examples of liquid-vapor fluids are examined and associated parameters are computed with the help of the present method. Comparisons between analytical and experimental saturation curves show very good agreement for wide ranges of temperature for both liquid and vapor.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    Ozima, M.

    2010-12-01

    The isotopic composition of noble gases is a key reference parameter in discussing the evolution of planetary atmospheres. Currently, two widely occurring noble gas components are identified in the early solar system, one is the Solar Wind noble gas (SW-noble gas, hereafter) and another is the Q-noble gas in unaltered meteorites: both noble gases are characterized by their ubiquitous occurrence and high isotopic homogeneity. Since the SW-noble gas is directly ejected from the Sun, it has been assumed to be a good proxy of the average noble gas isotopic composition in the Sun, namely the solar noble gas. The systematic enrichment of the heavier isotopes in the Q-noble gas relative to the SW-noble gas is then commonly attributed to its isotopic fractionation from the SW-noble gas. However, the isotopic compositions of the SW-noble gas either implanted on lunar soils or trapped by artificial targets show considerable isotopic variation depending on the velocity of the Solar Wind. Therefore, it is important to examine how closely the SW-noble gas represents the indigenous solar noble gas component or the mean isotopic composition of noble gases of the Sun. Here we show that the isotopic composition of the SW-noble gas is substantially fractionated relative to the solar value, and therefore should not be used as a reference parameter. We further suggest that the post D-burning Q-noble gas (see below) is the better proxy of the solar noble gas, and this should be used as a reference of the Solar noble gas isotopic composition in discussing the planetary atmospheric evolution. The most distinct difference between the Q- and the SW-noble gas is apparent in a 3He/4He isotopic ratio: 4.64e-4 in Q-He [1], but 1.23e-4 in SW-He[2]. The difference is attributed to the conversion of deuteron (D) to 3He in the Sun, namely the D-burning [3], due to high temperature during the pre-main sequence stage of the Sun. With the use of recent data on D/H ratios from helio-seismology [4] and

  4. Noble Gas Migration Experiment to Support the Detection of Underground Nuclear Explosions

    SciTech Connect

    Olsen, Khris B.; Kirkham, Randy R.; Woods, Vincent T.; Haas, Derek A.; Hayes, James C.; Bowyer, Ted W.; Mendoza, Donaldo P.; Lowrey, Justin D.; Lukins, Craig D.; Suarez, Reynold; Humble, Paul H.; Ellefson, Mark D.; Ripplinger, Mike D.; Zhong, Lirong; Mitroshkov, Alexandre V.; Aalseth, Craig E.; Prinke, Amanda M.; Mace, Emily K.; McIntyre, Justin I.; Stewart, Timothy L.; Mackley, Rob D.; Milbrath, Brian D.; Emer, Dudley; Biegalski, S.

    2016-03-01

    A Noble Gas Migration Experiment (NGME) funded by the National Center for Nuclear Security and conducted at the Nevada National Security Site (NNSS) in collaboration with Lawrence Livermore national Laboratory and National Security Technology provided critical on-site inspection (OSI) information related to the detection of an underground nuclear explosion (UNE) event using noble gas signatures.

  5. Development of a Liquefied Noble Gas Time Projection Chamber

    NASA Astrophysics Data System (ADS)

    Lesser, Ezra; White, Aaron; Aidala, Christine

    2015-10-01

    Liquefied noble gas detectors have been used for various applications in recent years for detecting neutrinos, neutrons, photons, and potentially dark matter. The University of Michigan is developing a detector with liquid argon to produce scintillation light and ionization electrons. Our data collection method will allow high-resolution energy measurement and spatial reconstruction of detected particles by using multi-pixel silicon photomultipliers (SiPM) and a cylindrical time projection chamber (TPC) with a multi-wire endplate. We have already designed a liquid argon condenser and purification unit surrounded by an insulating vacuum, constructed circuitry for temperature and pressure sensors, and created software to obtain high-accuracy sensor readouts. The status of detector development will be presented. Funded through the Michigan Memorial Phoenix Project.

  6. In Situ Noble-Gas Based Chronology on Mars

    NASA Technical Reports Server (NTRS)

    Swindle, T. D.

    2000-01-01

    Determining radiometric ages in situ on another planet's surface has never been done, and there are good reasons to think that it will be extremely difficult. It is certainly hard to imagine that such ages could be measured as precisely as they could be measured on returned samples in state-of-the-art terrestrial laboratories. However, it may be possible, by using simple noble-gas-based chronology techniques, to determine ages on Mars to a precision that is scientifically useful. This abstract will: (1) describe the techniques we envision; (2) give some examples of how such information might be scientifically useful; and (3) describe the system we are developing, including the requirements in terms of mass, power, volume, and sample selection and preparation.

  7. INGAS: Iranian Noble Gas Analyzing System for radioxenon measurement

    NASA Astrophysics Data System (ADS)

    Doost-Mohammadi, V.; Afarideh, H.; Etaati, G. R.; Safari, M. J.; Rouhi, H.

    2016-03-01

    In this article, Iranian Noble Gas Analyzing System (INGAS) will be introduced. This system is based on beta-gamma coincidence technique and consists of a well-type NaI(Tl) as gamma or X radiation detector and a cylindrical plastic scintillator to detect beta or conversion electron. Standard NIM modules were utilized to detect coincidence events of detectors. Both the beta and gamma detectors were appropriately calibrated. The efficiency curve of gamma detector for volume geometry was obtained by comparing the results of gamma point sources measurements and simulations of GATE V7.0 Monte Carlo code. The performance of detection system was checked by injection of 222Rn and 131mXe gaseous source in the detection cell. The minimum detectable activity of the system for 133Xe is 1.240±0.024 mBq for 24 h measurement time.

  8. The Noble-Abel Stiffened-Gas equation of state

    SciTech Connect

    Le Métayer, Olivier; Saurel, Richard

    2016-04-15

    Hyperbolic two-phase flow models have shown excellent ability for the resolution of a wide range of applications ranging from interfacial flows to fluid mixtures with several velocities. These models account for waves propagation (acoustic and convective) and consist in hyperbolic systems of partial differential equations. In this context, each phase is compressible and needs an appropriate convex equation of state (EOS). The EOS must be simple enough for intensive computations as well as boundary conditions treatment. It must also be accurate, this being challenging with respect to simplicity. In the present approach, each fluid is governed by a novel EOS named “Noble Abel stiffened gas,” this formulation being a significant improvement of the popular “Stiffened Gas (SG)” EOS. It is a combination of the so-called “Noble-Abel” and “stiffened gas” equations of state that adds repulsive effects to the SG formulation. The determination of the various thermodynamic functions and associated coefficients is the aim of this article. We first use thermodynamic considerations to determine the different state functions such as the specific internal energy, enthalpy, and entropy. Then we propose to determine the associated coefficients for a liquid in the presence of its vapor. The EOS parameters are determined from experimental saturation curves. Some examples of liquid-vapor fluids are examined and associated parameters are computed with the help of the present method. Comparisons between analytical and experimental saturation curves show very good agreement for wide ranges of temperature for both liquid and vapor.

  9. Noble gas partitioning behavior in the Sleipner Vest hydrocarbon field

    NASA Astrophysics Data System (ADS)

    Barry, P. H.; Lawson, M.; Warr, O.; Mabry, J.; Byrne, D. J.; Meurer, W. P.; Ballentine, C. J.

    2015-12-01

    Noble gases are chemically inert and variably soluble in crustal fluids. They are primarily introduced into hydrocarbon reservoirs through exchange with formation waters, and can be used to assess migration pathways, mechanisms and reservoir storage. Of particular interest is the role groundwater plays in hydrocarbon transport, which is reflected in hydrocarbon-water volume ratios. We present compositional, stable isotope and noble gas isotope and abundance data from the Sleipner Vest field, in the Norwegian North Sea. Sleipner gases are generated from primary cracking of kerogen and the thermal cracking of oil, sourced from type II marine source, with relatively homogeneous maturities and a range in vitrinite reflectance (1.2-1.7%). Gases are hosted in the lower shoreface sandstones of the Jurassic Hugin formation, which is sealed by the Jurassic Upper Draupne and Heather formations. Gases are composed of N2 (0.6-0.9%), CO2 (5.4-15.3%) and hydrocarbons (69-80%). Helium isotopes (3He/4He) are radiogenic and range from 0.065 to 0.116 RA, showing a small mantle contribution, consistent with Ne isotopes (20Ne/22Ne from 9.70-9.91; 21Ne/22Ne from 0.0290-0.0344) and Ar isotopes (40Ar/36Ar from 315-489). 20Ne/36Ar, 84Kr/36Ar and 132Xe/36Ar values are systematically higher relative to air saturated water ratios. These data are discussed within the framework of several conceptual models: i) Total gas-stripping model, which defines the minimum volume of water to have interacted with the hydrocarbon phase; ii) Equilibrium model, assuming simple equilibration between groundwater and hydrocarbon phase at reservoir P,T and salinity; and iii) Open and closed system gas-stripping models. Using Ne-Ar, we estimate gas-water ratios for the Sleipner system of 0.02-0.09, which compare with geologic gas-water estimates of ~0.24, and suggest more groundwater interaction than a static system estimate. Kr and Xe show evidence for an additional source or process involving oil or sediments.

  10. High Pressure Noble Gas Alkali Vapor Mixtures and Their Visible and Infrared Excimer Bands.

    DTIC Science & Technology

    1980-02-01

    0AA629-77--015 UNCLASSIFIED AR0-1A223.A-P NL -Y IGH PRESSURE NOBLE GAS ALKALI VAPOR MIXTURES AND THEIR VISIBLE AND INFRARED EXCIMER BANDS, FINAL REPORT...Final Report 4. TITLE (and $ubtItze) S. TYPE OF REPORT & PERIOD COVERED HIGH PRESSURF NOBLE GAS ALKALI VAPOR MIXTURES Final 11/15/76 - 11/14/79 AND...emission bands from transitions between excited states of cesium- noble gas molecules," J. Chem. Phys. 71, 4052 (1979). N. D. Bhaskar, E. Zouboulis, R

  11. Noble gas signatures in the Island of Maui, Hawaii: Characterizing groundwater sources in fractured systems

    USGS Publications Warehouse

    Niu, Yi; Castro, M. Clara; Hall, Chris M.; Gingerich, Stephen B.; Scholl, Martha A.; Warrier, Rohit B.

    2017-01-01

    Uneven distribution of rainfall and freshwater scarcity in populated areas in the Island of Maui, Hawaii, renders water resources management a challenge in this complex and ill-defined hydrological system. A previous study in the Galapagos Islands suggests that noble gas temperatures (NGTs) record seasonality in that fractured, rapid infiltration groundwater system rather than the commonly observed mean annual air temperature (MAAT) in sedimentary systems where infiltration is slower thus, providing information on recharge sources and potential flow paths. Here we report noble gas results from the basal aquifer, springs, and rainwater in Maui to explore the potential for noble gases in characterizing this type of complex fractured hydrologic systems. Most samples display a mass-dependent depletion pattern with respect to surface conditions consistent with previous observations both in the Galapagos Islands and Michigan rainwater. Basal aquifer and rainwater noble gas patterns are similar and suggest direct, fast recharge from precipitation to the basal aquifer. In contrast, multiple springs, representative of perched aquifers, display highly variable noble gas concentrations suggesting recharge from a variety of sources. The distinct noble gas patterns for the basal aquifer and springs suggest that basal and perched aquifers are separate entities. Maui rainwater displays high apparent NGTs, incompatible with surface conditions, pointing either to an origin at high altitudes with the presence of ice or an ice-like source of undetermined origin. Overall, noble gas signatures in Maui reflect the source of recharge rather than the expected altitude/temperature relationship commonly observed in sedimentary systems.

  12. Noble gas signatures in the Island of Maui, Hawaii: Characterizing groundwater sources in fractured systems

    NASA Astrophysics Data System (ADS)

    Niu, Yi; Castro, M. Clara; Hall, Chris M.; Gingerich, Stephen B.; Scholl, Martha A.; Warrier, Rohit B.

    2017-05-01

    Uneven distribution of rainfall and freshwater scarcity in populated areas in the Island of Maui, Hawaii, renders water resources management a challenge in this complex and ill-defined hydrological system. A previous study in the Galapagos Islands suggests that noble gas temperatures (NGTs) record seasonality in that fractured, rapid infiltration groundwater system rather than the commonly observed mean annual air temperature (MAAT) in sedimentary systems where infiltration is slower thus, providing information on recharge sources and potential flow paths. Here we report noble gas results from the basal aquifer, springs, and rainwater in Maui to explore the potential for noble gases in characterizing this type of complex fractured hydrologic systems. Most samples display a mass-dependent depletion pattern with respect to surface conditions consistent with previous observations both in the Galapagos Islands and Michigan rainwater. Basal aquifer and rainwater noble gas patterns are similar and suggest direct, fast recharge from precipitation to the basal aquifer. In contrast, multiple springs, representative of perched aquifers, display highly variable noble gas concentrations suggesting recharge from a variety of sources. The distinct noble gas patterns for the basal aquifer and springs suggest that basal and perched aquifers are separate entities. Maui rainwater displays high apparent NGTs, incompatible with surface conditions, pointing either to an origin at high altitudes with the presence of ice or an ice-like source of undetermined origin. Overall, noble gas signatures in Maui reflect the source of recharge rather than the expected altitude/temperature relationship commonly observed in sedimentary systems.

  13. Catalytic activities of noble metal atoms on WO3 (001): nitric oxide adsorption.

    PubMed

    Ren, Xiaoyan; Zhang, Shuai; Li, Chong; Li, Shunfang; Jia, Yu; Cho, Jun-Hyung

    2015-01-01

    Using first-principles density functional theory calculations within the generalized gradient approximation, we investigate the adsorption of NO molecule on a clean WO3(001) surface as well as on the noble metal atom (Cu, Ag, and Au)-deposited WO3(001) surfaces. We find that on a clean WO3 (001) surface, the NO molecule binds to the W atom with an adsorption energy (E ads) of -0.48 eV. On the Cu- and Ag-deposited WO3(001) surface where such noble metal atoms prefer to adsorb on the hollow site, the NO molecule also binds to the W atom with E ads = -1.69 and -1.41 eV, respectively. This relatively stronger bonding of NO to the W atom is found to be associated with the larger charge transfer of 0.43 e (Cu) and 0.33 e (Ag) from the surface to adsorbed NO. However, unlike the cases of Cu-WO3(001) and Ag-WO3(001), Au atoms prefer to adsorb on the top of W atom. On such an Au-WO3(001) complex, the NO molecule is found to form a bond to the Au atom with E ads = -1.32 eV. Because of a large electronegativity of Au atom, the adsorbed NO molecule captures the less electrons (0.04 e) from the surface compared to the Cu and Ag catalysts. Our findings not only provide useful information about the NO adsorption on a clean WO3(001) surface as well as on the noble metal atoms deposited WO3(001) surfaces but also shed light on a higher sensitive WO3 sensor for NO detection employing noble metal catalysts.

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

    PubMed

    Sumpf; Bouazza; Kissel; Kronfeldt

    2000-02-01

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

  15. 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.

  16. 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.

  17. Light noble gas chemistry: Structures, stabilities, and bonding of helium, neon and argon compounds

    SciTech Connect

    Frenking, G. ); Koch, W. ); Reichel, F. ); Cremer, D. )

    1990-05-23

    Theoretically determined geometries are reported for the light noble gas ions Ng{sub 2}C{sup 2+}, Ng{sub 2}N{sup 2+}, Ng{sub 2}O{sup 2+}, NgCCNg{sup 2+}, NgCCH{sup +}, NgCN{sup +}, and NgNC{sup +} (Ng = He, Ne, Ar) at the MP2/6-31G(d,p) level of theory. In a few cases, optimizations were carried out at CASSCF/6-31G(d,p). The thermodynamic stability of the Ng compounds is investigated at MP4(SDTQ)/6-311G(2df,2pd) for Ng = He, Ne and at MP4(SDTQ)/6-311G(d,p) for Ng = Ar. The structures and stabilities of the molecules are discussed in terms of donor-acceptor interactions between Ng and the respective fragment cation, by using molecular orbital arguments and utilizing the analysis of the electron density distribution and its associated Laplace field. Generally, there is an increase in Ng,X binding interactions of a noble gas molecule NgX with increasing atomic size of Ng. In some cases the Ne,X stabilization energies are slightly smaller than the corresponding He,X values because of repulsive p-{pi} interactions in the neon compounds. The argon molecules are in all cases significantly stronger bound.

  18. Noble Gas Measurement and Analysis Technique for Monitoring Reprocessing Facilities

    SciTech Connect

    Charlton, William S

    1999-09-01

    An environmental monitoring technique using analysis of stable noble gas isotopic ratios on-stack at a reprocessing facility was developed. This technique integrates existing technologies to strengthen safeguards at reprocessing facilities. The isotopic ratios are measured using a mass spectrometry system and are compared to a database of calculated isotopic ratios using a Bayesian data analysis method to determine specific fuel parameters (e.g., burnup, fuel type, fuel age, etc.). These inferred parameters can be used by investigators to verify operator declarations. A user-friendly software application (named NOVA) was developed for the application of this technique. NOVA included a Visual Basic user interface coupling a Bayesian data analysis procedure to a reactor physics database (calculated using the Monteburns 3.01 code system). The integrated system (mass spectrometry, reactor modeling, and data analysis) was validated using on-stack measurements during the reprocessing of target fuel from a U.S. production reactor and gas samples from the processing of EBR-II fast breeder reactor driver fuel. These measurements led to an inferred burnup that matched the declared burnup with sufficient accuracy and consistency for most safeguards applications. The NOVA code was also tested using numerous light water reactor measurements from the literature. NOVA was capable of accurately determining spent fuel type, burnup, and fuel age for these experimental results. Work should continue to demonstrate the robustness of this system for production, power, and research reactor fuels.

  19. Experimental studies and model analysis of noble gas fractionation in low-permeability porous media

    NASA Astrophysics Data System (ADS)

    Ding, Xin; Mack Kennedy, B.; Molins, Sergi; Kneafsey, Timothy; Evans, William C.

    2017-05-01

    Gas flow through the vadose zone from sources at depth involves fractionation effects that can obscure the nature of transport and even the identity of the source. Transport processes are particularly complex in low permeability media but as shown in this study, can be elucidated by measuring the atmospheric noble gases. A series of laboratory column experiments was conducted to evaluate the movement of noble gas from the atmosphere into soil in the presence of a net efflux of CO2, a process that leads to fractionation of the noble gases from their atmospheric abundance ratios. The column packings were designed to simulate natural sedimentary deposition by interlayering low permeability ceramic plates and high permeability beach sand. Gas samples were collected at different depths at CO2 fluxes high enough to cause extreme fractionation of the noble gases (4He/36Ar > 20 times the air ratio). The experimental noble gas fractionation-depth profiles were in good agreement with those predicted by the dusty gas (DG) model, demonstrating the applicability of the DG model across a broad spectrum of environmental conditions. A governing equation based on the dusty gas model was developed to specifically describe noble gas fractionation at each depth that is controlled by the binary diffusion coefficient, Knudsen diffusion coefficient and the ratio of total advection flux to total flux. Finally, the governing equation was used to derive the noble gas fractionation pattern and illustrate how it is influenced by soil CO2 flux, sedimentary sequence, thickness of each sedimentary layer and each layer's physical parameters. Three potential applications of noble gas fractionation are provided: evaluating soil attributes in the path of gas flow from a source at depth to the atmosphere, testing leakage through low permeability barriers used to isolate buried waste, and tracking biological methanogenesis and methane oxidation associated with hydrocarbon degradation.

  20. Comparison of induced damage, range, reflection, and sputtering yield between amorphous, bcc crystalline, and bubble-containing tungsten materials under hydrogen isotope and noble gas plasma irradiations

    NASA Astrophysics Data System (ADS)

    Saito, Seiki; Nakamura, Hiroaki; Tokitani, Masayuki

    2017-01-01

    Binary-collision-approximation simulation of hydrogen isotope (i.e., hydrogen, deuterium, and tritium) and noble gas (i.e., helium, neon, and argon) injections into tungsten materials is performed. Three tungsten structures (i.e., amorphous, bcc crystalline, and helium bubble-containing structures) are prepared as target materials. Then, the trajectories of incident atoms, the distribution of recoil atoms, the penetration depth range of incident atoms, the sputtering yield, and the reflection rate are carefully investigated for these target materials.

  1. 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.

  2. Neutron detection with noble gas scintillation: a review of recent results

    NASA Astrophysics Data System (ADS)

    Lavelle, C. M.; Coplan, Michael; Miller, Eric C.; Thompson, Alan K.; Kowler, Alex; Vest, Rob; Yue, Andrew; Koeth, Tim; Al-Sheikhly, Mohammad; Clark, Charles

    2015-08-01

    Thermal neutron detection is of vital importance to many disciplines, including neutron scattering, workplace monitoring, and homeland protection. We survey recent results from our collaboration which couple low-pressure noble gas scintillation with novel approaches to neutron absorbing materials and geometries to achieve potentially advantageous detector concepts. Noble gas scintillators were used for neutron detection as early as the late 1950's. Modern use of noble gas scintillation includes liquid and solid forms of argon and xenon in the dark matter and neutron physics experiments and commercially available high pressure applications have achieved high resolution gamma ray spectroscopy. Little attention has been paid to the overlap between low pressure noble gas scintillation and thermal neutron detection, for which there are many potential benefits.

  3. Noble Gas Inventory of Transantarctic Mountain Micrometeorites: Insights into Their Provenance

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    We summarize results from a noble gas study of micrometeorites collected in traps on the tops of the Transantarctic Mountains. Cosmogenic Ne is compared with model predictions. One micrometeorite may be linked to an achondritic source.

  4. Pyroxenes from Governador Valadares and Lafayette: A Nitrogen and Noble Gas Study

    NASA Astrophysics Data System (ADS)

    Schwenzer, S. P.; Herrmann, S.; Ott, U.

    2006-03-01

    We present new noble gas and nitrogen data on pyroxene separates from Lafayette and Governador Valadares [rad. 4He, cosmogenic nuclides (in Ne, Ar), martian interior, fractionated and unfractionated martian, and fractionated terrestrial atmosphere].

  5. 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

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

    PubMed

    Holland, Greg; Ballentine, Chris J

    2006-05-11

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

  7. 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.

  8. Review: gas-phase ion chemistry of the noble gases: recent advances and future perspectives.

    PubMed

    Grandinetti, Felice

    2011-01-01

    This review article surveys recent experimental and theoretical advances in the gas-phase ion chemistry of the noble gases. Covered issues include the interaction of the noble gases with metal and non-metal cations, the conceivable existence of covalent noble-gas anions, the occurrence of ion-molecule reactions involving singly-charged xenon cations, and the occurrence of bond-forming reactions involving doubly-charged cations. Research themes are also highlighted, that are expected to attract further interest in the future.

  9. Noble gas excess air applied to distinguish groundwater recharge conditions.

    PubMed

    Ingram, Richard G S; Hiscock, Kevin M; Dennis, Paul F

    2007-03-15

    The application of geochemical tracers in groundwater studies can provide valuable insights into the rates and sources of groundwater recharge, residence times, and flow dynamics that are of significant value in the management of this important natural resource. This paper demonstrates the application of noble gas excess air to distinguish groundwater bodies with different recharge histories in a layered sandstone aquifer system in the east of England. The sampled groundwaters are all supersaturated with respect to neon, indicating the presence of excess air. The lowest excess air concentrations occur where the aquifer is unconfined (deltaNe, the proportion of neon in excess of saturation, = 12-26%) and recharge occurs directly to the outcrop. Groundwater in the confined part of the aquifer can be divided into two hydrochemical types based upon the dissolved ion chemistry: Type 1 groundwaters contain more excess air (deltaNe = 115-120%) than Type 2(deltaNe = 22-62%). The difference in excess air concentrations confirms that groundwater enters the confined aquifer along two discrete pathways. Furthermore, excess neon concentrations predicted from the magnitude of annual water table fluctuation observed in the different recharge areas are in good agreement with those measured in the corresponding groundwaters. We therefore recommend that excess air may be usefully employed as a direct indicator of the volume of long-term net annual groundwater recharge.

  10. 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.

  11. Theoretical study of noble-gas containing metal halides

    NASA Astrophysics Data System (ADS)

    Mou, Chun-Hao; Witek, Henryk A.

    2008-12-01

    Equilibrium structures, energetic stability, and vibrational frequencies of noble-gas containing metal halides, MNgX and NgMX (Ng=Ar,Kr,Xe; M=Cu,Ag,Au; X=F,Cl,Br) have been studied computationally using coupled cluster, density functional, and perturbation techniques. The NgMX species have been found to be stable with the Ng-M bond dissociation energy of 2-22 kcal/mol. Our calculations indicate that the argon-containing MNgX compounds are unstable or very weakly bound. For most of the krypton- and xenon-containing species, well-defined (MNg)δ+Xδ- equilibrium structures have been located. Large MNgX-->Ng+MX reorganization barriers for some of the MNgX molecules (e.g., AuXeF and AuXeCl) indicate their considerable kinetic stability. The presented results suggest that direct observation of the most stable of the MNgX molecules might be possible in experiment.

  12. Carbon and Noble Gas Isotope Banks in Two-Phase Flow: Changes in Gas Composition During Migration

    NASA Astrophysics Data System (ADS)

    Sathaye, K.; Larson, T.; Hesse, M. A.

    2015-12-01

    In conjunction with the rise of unconventional oil and gas production, there has been a recent rise in interest in noble gas and carbon isotope changes that can occur during the migration of natural gas. Natural gas geochemistry studies use bulk hydrocarbon composition, carbon isotopes, and noble gas isotopes to determine the migration history of gases from source to reservoir, and to trace fugitive gas leaks from reservoirs to shallow groundwater. We present theoretical and experimental work, which helps to explain trends observed in gas composition in various migration scenarios. Noble gases are used as tracers for subsurface fluid flow due to distinct initial compositions in air-saturated water and natural gases. Numerous field studies have observed enrichments and depletions of noble gases after gas-water interaction. A theoretical two-phase gas displacement model shows that differences in noble gas solubility will cause volatile gas components will become enriched at the front of gas plumes, leaving the surrounding residual water stripped of dissolved gases. Changes in hydrocarbon gas composition are controlled by gas solubility in both formation water and residual oil. In addition to model results, we present results from a series of two-phase flow experiments. These results demonstrate the formation of a noble gas isotope banks ahead of a main CO2 gas plume. Additionally, we show that migrating hydrocarbon gas plumes can sweep biogenic methane from groundwater, significantly altering the isotope ratio of the gas itself. Results from multicomponent, two-phase flow experiments qualitatively agree with the theoretical model, and previous field studies. These experimentally verified models for gas composition changes can be used to aid source identification of subsurface gases.

  13. 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.

  14. Applicability of Monte-Carlo Simulation to Equipment Design of Radioactive Noble Gas Monitor

    NASA Astrophysics Data System (ADS)

    Sakai, Hirotaka; Hattori, Kanako; Umemura, Norihiro

    In the nuclear facilities, radioactive noble gas is continuously monitored by using the radioactive noble gas monitor with beta-sensitive plastic scintillation radiation detector. The detection efficiency of the monitor is generally calibrated by using a calibration loop and standard radioactive noble gases such as 85Kr. In this study, the applicability of PHITS to the equipment design of the radioactive noble gas monitor was evaluated by comparing the calculated results to the test results obtained by actual calibration loop tests to simplify the radiation monitor design evaluation. It was confirmed that the calculated results were well matched to the test results of the monitor after the modeling. In addition, the key parameters for equipment design, such as thickness of detector window or depth of the sampler, were also specified and evaluated.

  15. Modeling soil gas dynamics in the context of noble gas tracer applications

    NASA Astrophysics Data System (ADS)

    Jenner, Florian; Mayer, Simon; Aeschbach, Werner; Peregovich, Bernhard; Machado, Carlos

    2017-04-01

    Noble gas tracer applications show a particular relevance for the investigation of gas dynamics in the unsaturated zone, but also for a treatment of soil contamination as well as concerning exchange processes between soil and atmosphere. In this context, reliable conclusions require a profound understanding of underlying biogeochemical processes. With regard to noble gas tracer applications, the dynamics of reactive and inert gases in the unsaturated zone is investigated. Based on long-term trends and varying climatic conditions, this is the first study providing general insights concerning the role of unsaturated zone processes. Modeling approaches are applied, in combination with an extensive set of measured soil air composition data from appropriate sampling sites. On the one hand, a simple modeling approach allows to identify processes which predominantly determine inert gas mixing ratios in soil air. On the other hand, the well-proven and sophisticated modeling routine Min3P is applied to describe the measured data by accounting for the complex nature of subsurface gas dynamics. Both measured data and model outcomes indicate a significant deviation of noble gas mixing ratios in soil air from the respective atmospheric values, occurring on seasonal scale. Observed enhancements of noble gas mixing ratios are mainly caused by an advective balancing of depleted sum values of O2+CO2, resulting from microbial oxygen depletion in combination with a preferential dissolution of CO2. A contrary effect, meaning an enhanced sum value of O2+CO2, is shown to be induced at very dry conditions due to the different diffusivities of O2 and CO2. Soil air composition data show a yearlong mass-dependent fractionation, occurring as a relative enhancement of heavier gas species with respect to lighter ones. The diffusive balancing of concentration gradients between soil air and atmosphere is faster for lighter gas species compared to heavier ones. The rather uniform fractionation is

  16. From single atoms to self-assembled quantum single-atomic nanowires: noble metal atoms on black phosphorene monolayers.

    PubMed

    Zhao, X J; Shan, Wen-Wen; He, Hao; Xue, Xinlian; Guo, Z X; Li, S F

    2017-03-15

    Transition metal (TM) nanostructures, such as one dimensional (1D) nanowires with/without substrates, usually possess drastically different properties from their bulk counterparts, due to their distinct stacking and electronic confinement. Correspondingly, it is of great importance to establish the dominant driving force in forming 1D single-metal-atom-wires (SMAWs). Here, with first-principles calculations, taking the black phosphorene (BP) monolayer as a prototype 2D substrate, we investigate the energetic and kinetic properties of all the 5d-TM atoms on the 2D substrate to reveal the mechanism of formation of SMAWs. In contrast to other 5d- and 4d-TMs, noble metal elements Pd and Pt are found to prefer to grow along the trough in an atom-by-atom manner, self-assembling into SMAWs with a significant magic growth behavior. This is due to distinct binding energies and diffusion barriers along the trough, i.e., zig-zag direction, as compared to other directions of the BP. The present findings are valuable in the fabrication and modulation of 1D nanostructures which can be anticipated to possess desirable functionalities for potential applications such as in nanocatalysis, nanosensors, and related areas.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  18. Helium Isotopes and Noble Gas Abundances of Cave Dripping Water in Three Caves in East Asia

    NASA Astrophysics Data System (ADS)

    Chen, A. T.; Shen, C. C.; Tan, M.; Li, T.; Uemura, R.; Asami, R.

    2015-12-01

    Paleo-temperature recorded in nature archives is a critical parameter to understand climate change in the past. With advantages of unique inert chemical characteristics and sensitive solubilities with temperature, dissolved noble gases in speleothem inclusion water were recently proposed to retrieve terrestrial temperature history. In order to accurately apply this newly-developed speleothem noble gas temperature (NGT) as a reliable proxy, a fundamental issue about behaviors of noble gases in the karst should be first clarified. In this study, we measured noble gas contents in air and dripping water to evaluate any ratio deviation between noble gases. Cave dripping water samples was collected from three selected caves, Shihua Cave in northern China, Furong Cave in southwestern, and Gyukusen Cave in an island located in the western Pacific. For these caves are characterized by a thorough mixing and long-term storage of waters in a karst aquifer by the absence of seasonal oxygen isotope shifts. Ratios of dripping water noble gases are statistically insignificant from air data. Helium isotopic ratios in the dripping water samples match air value. The results indicate that elemental and isotopic signatures of noble gases from air can be frankly preserved in the epikarst and support the fidelity of NGT techniques.

  19. Noble gases in gas shales : Implications for gas retention and circulating fluids.

    NASA Astrophysics Data System (ADS)

    Basu, Sudeshna; Jones, Adrian; Verchovsky, Alexander

    2016-04-01

    Gas shales from three cores of Haynesville-Bossier formation have been analysed simultaneously for carbon, nitrogen and noble gases (He, Ne, Ar, Xe) to constrain their source compositions and identify signatures associated with high gas retention. Ten samples from varying depths of 11785 to 12223 feet from each core, retrieved from their centres, have been combusted from 200-1200°C in incremental steps of 100°C, using 5 - 10 mg of each sample. Typically, Xe is released at 200°C and is largely adsorbed, observed in two of the three cores. The third core lacked any measureable Xe. High 40Ar/36Ar ratio up to 8000, is associated with peak release of nitrogen with distinctive isotopic signature, related to breakdown of clay minerals at 500°C. He and Ne are also mostly released at the same temperature step and predominantly hosted in the pore spaces of the organic matter associated with the clay. He may be produced from the uranium related to the organic matter. The enrichment factors of noble gases defined as (iX/36Ar)sample/(iX/36Ar)air where iX denotes any noble gas isotope, show Ne and Xe enrichment observed commonly in sedimentary rocks including shales (Podosek et al., 1980; Bernatowicz et al., 1984). This can be related to interaction of the shales with circulating fluids and diffusive separation of gases (Torgersen and Kennedy, 1999), implying the possibility of loss of gases from these shales. Interaction with circulating fluids (e.g. crustal fluids) have been further confirmed using 20Ne/N2, 36Ar/N2 and 4He/N2 ratios. Deviations of measured 4He/40Ar* (where 40Ar* represents radiogenic 40Ar after correcting for contribution from atmospheric Ar) from expected values has been used to monitor gas loss by degassing. Bernatowicz, T., Podosek, F.A., Honda, M., Kramer, F.E., 1984. The Atmospheric Inventory of Xenon and Noble Gases in Shales: The Plastic Bag Experiment. Journal of Geophysical Research 89, 4597-4611. Podosek, F.A., Honda, M., Ozima, M., 1980

  20. 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.

  1. 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.

  2. Equivalent electron correlations in nonsequential double ionization of noble atoms

    NASA Astrophysics Data System (ADS)

    Dong, Shansi; Han, Qiujing; Zhang, Jingtao

    2017-02-01

    Electron correlation is encoded directly in the distribution of the energetic electrons produced in a recollision-impact double ionization process, and varies with the laser field and the target atoms. In order to get equivalent electron correlation effects, one should enlarge the laser intensity cubically and the laser frequency linearly in proportion to the second ionization potentials of the target atoms. The physical mechanism behind the transform is to keep the ponderomotive parameter unchanged when the laser frequency is enlarged. Project supported by the National Natural Science Foundation of China (Grant Nos. 61475168 and 11674231) and sponsored by Shanghai Gaofeng & Gaoyuan Project for University Academic Program Development (Zhang).

  3. Assessment of the readiness of noble gas equipment for field operation in the IMS network

    NASA Astrophysics Data System (ADS)

    Wernsperger, Bernd; Auer, Matthias; Gohla, Herbert; Khrustalev, Kirill

    2010-05-01

    The radionuclide component of the International Monitoring System (IMS) consists of 80 radionuclide stations, of which 40 are equipped with noble-gas monitoring capability. Prior to the set-up of the IMS network, noble gas monitoring was only performed by a few institutions using manual, laboratory based systems. The deployment of noble gas systems in a world-wide network of monitoring stations required development of a new generation of equipment, which is reliable, suited for automated field operation at a detection sensitivity lower than previously achieved in laboratory based systems. New types of equipment have been developed and undergone extensive testing during the last 10 years under the framework of the ongoing International Noble Gas Experiment (INGE). During Phase III of INGE, three different types of noble gas systems are deployed into the IMS for testing. With altogether 17 systems in the field between 2004 to 2008 experience of more than 37 operational years has been accumulated. Operational parameters of the noble gas systems have improved during the entire Phase III from the first systems towards the latest state-of the art system generations. To ensure minimum down time any operational problems are addressed within the support system inside the PTS. Within this support system the operational performance is continuously monitored and particular problems are identified. The solution of operational problems is the joint objective of the PTS, the station operators and the system suppliers. Equipment reliability, operational procedures, maintenance and sparing plans are continuously reviewed and improved. The operational status of the IMS noble gas network during the Phase III exercise as well as the support strategy is presented.

  4. Protein-protected luminescent noble metal quantum clusters: an emerging trend in atomic cluster nanoscience

    PubMed Central

    Xavier, Paulrajpillai Lourdu; Chaudhari, Kamalesh; Baksi, Ananya; Pradeep, Thalappil

    2012-01-01

    Noble metal quantum clusters (NMQCs) are the missing link between isolated noble metal atoms and nanoparticles. NMQCs are sub-nanometer core sized clusters composed of a group of atoms, most often luminescent in the visible region, and possess intriguing photo-physical and chemical properties. A trend is observed in the use of ligands, ranging from phosphines to functional proteins, for the synthesis of NMQCs in the liquid phase. In this review, we briefly overview recent advancements in the synthesis of protein protected NMQCs with special emphasis on their structural and photo-physical properties. In view of the protein protection, coupled with direct synthesis and easy functionalization, this hybrid QC-protein system is expected to have numerous optical and bioimaging applications in the future, pointers in this direction are visible in the literature. PMID:22312454

  5. Protein-protected luminescent noble metal quantum clusters: an emerging trend in atomic cluster nanoscience.

    PubMed

    Xavier, Paulrajpillai Lourdu; Chaudhari, Kamalesh; Baksi, Ananya; Pradeep, Thalappil

    2012-01-01

    Noble metal quantum clusters (NMQCs) are the missing link between isolated noble metal atoms and nanoparticles. NMQCs are sub-nanometer core sized clusters composed of a group of atoms, most often luminescent in the visible region, and possess intriguing photo-physical and chemical properties. A trend is observed in the use of ligands, ranging from phosphines to functional proteins, for the synthesis of NMQCs in the liquid phase. In this review, we briefly overview recent advancements in the synthesis of protein protected NMQCs with special emphasis on their structural and photo-physical properties. In view of the protein protection, coupled with direct synthesis and easy functionalization, this hybrid QC-protein system is expected to have numerous optical and bioimaging applications in the future, pointers in this direction are visible in the literature.

  6. Noble gas loss may indicate groundwater flow across flow barriers in southern Nevada

    USGS Publications Warehouse

    Thomas, J.M.; Bryant, Hudson G.; Stute, M.; Clark, J.F.

    2003-01-01

    Average calculated noble gas temperatures increase from 10 to 22oC in groundwater from recharge to discharge areas in carbonate-rock aquifers of southern Nevada. Loss of noble gases from groundwater in these regional flow systems at flow barriers is the likely process that produces an increase in recharge noble gas temperatures. Emplacement of low permeability rock into high permeability aquifer rock and the presence of low permeability shear zones reduce aquifer thickness from thousands to tens of meters. At these flow barriers, which are more than 1,000 m lower than the average recharge altitude, noble gases exsolve from the groundwater by inclusion in gas bubbles formed near the barriers because of greatly reduced hydrostatic pressure. However, re-equilibration of noble gases in the groundwater with atmospheric air at the low altitude spring discharge area, at the terminus of the regional flow system, cannot be ruled out. Molecular diffusion is not an important process for removing noble gases from groundwater in the carbonate-rock aquifers because concentration gradients are small.

  7. Performance of the High Resolution, Multi-collector Helix MC Plus Noble Gas Mass Spectrometer at the Australian National University.

    PubMed

    Zhang, Xiaodong; Honda, Masahiko; Hamilton, Doug

    2016-12-01

    Performance of the Helix MC Plus noble gas mass spectrometer installed at the Australian National University (ANU) is reported. Results for sensitivity, mass discrimination and their linearity against partial pressure of noble gases, and mass resolution of the mass spectrometer are presented, and the results are compared with those of conventional noble gas mass spectrometers. The application of the five detectors on the Helix MC Plus in measuring various noble gas isotopes in multi-collector modes and the integration of the software drivers of peripheral hardware devices into the controlling program Qtegra of the mass spectrometer are discussed. High mass resolution (>1800) and mass resolving power (>8000) make this mass spectrometer unique in noble gas cosmo-geochemistry. It provides the capability to measure isobaric interference-free noble gas isotopes in multi-collector mode, significantly improves the accuracy to determine isotopic ratios, and greatly increases the efficiency of data acquisition. Graphical Abstract ᅟ.

  8. Performance of the High Resolution, Multi-collector Helix MC Plus Noble Gas Mass Spectrometer at the Australian National University

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaodong; Honda, Masahiko; Hamilton, Doug

    2016-12-01

    Performance of the Helix MC Plus noble gas mass spectrometer installed at the Australian National University (ANU) is reported. Results for sensitivity, mass discrimination and their linearity against partial pressure of noble gases, and mass resolution of the mass spectrometer are presented, and the results are compared with those of conventional noble gas mass spectrometers. The application of the five detectors on the Helix MC Plus in measuring various noble gas isotopes in multi-collector modes and the integration of the software drivers of peripheral hardware devices into the controlling program Qtegra of the mass spectrometer are discussed. High mass resolution (>1800) and mass resolving power (>8000) make this mass spectrometer unique in noble gas cosmo-geochemistry. It provides the capability to measure isobaric interference-free noble gas isotopes in multi-collector mode, significantly improves the accuracy to determine isotopic ratios, and greatly increases the efficiency of data acquisition.

  9. Noble Gas Recycling: Experimental Constraints on Ar, Kr, and Xe Solubility in Serpentinite

    NASA Astrophysics Data System (ADS)

    Krantz, J. A.; Parman, S. W.; Kelley, S. P.; Smye, A.; Jackson, C.; Cooper, R. F.

    2016-12-01

    To constrain the rate of noble gas (NG) recycling at subduction zones, experiments have been performed to constrain the solubility of NG in natural antigorite. Geochemical analyses of exhumed subduction zone material1, well gases2, OIB and MORB3 indicate that NG are recycled from the surface of the earth into the mantle. The mechanism by which uncharged atoms can be bound to a mineral and subsequently recycled remains unclear, but experimental work suggests that ring structures in silicate minerals are ideal sites for NG4. Serpentine contains such ring structures and is abundant in subducting slabs, providing significant potential for control of the recycling of NG. Developing an understanding of how NG are transported may shed light on the large scale mantle dynamics associated with subduction, convection, and mantle heterogeneity. Experiments were performed in a cold seal pressure vessel at 350°C using a mix of either equal parts He, Ne, and Ar or Ar, Kr, and Xe as the pressure medium. Pressures varied from 0.15 to 1.13 kbar total pressure and durations varied from 20 to 188 hours. Samples were analyzed by UV laser ablation, noble gas mass spectrometry at The Open University, UK. White light interferometry was used to determine the volume of laser ablation pits from which concentrations were calculated. The data indicate that solubilities of NG in serpentinite are high in antigorite, and that variations in the solubility of NG could fractionate NG during recycling. 1. Kendrick, M.A., Scambelluri, M., Honda, M., Phillips, D., Nature Geoscience, 4, 807-812, 2011 2. Holland, G., and Ballentine, C.J., Nature, 441, 186-191, 2006 3. Parai, R. and Mukhopadhyay, S., GGG, 16, 719-735, 2015 4. Jackson, C.R.M., Parman, S.W., Kelley, S.P., Cooper, R.F., GCA, 159, 1-15, 2015

  10. 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.

  11. 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

  12. 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.

  13. The ATTA-Hefei Instrument for Radioactive Noble-gas Dating

    NASA Astrophysics Data System (ADS)

    Hu, S.; Cheng, C.; Cheng, G.; Sun, Y. R.; Tu, L.; Yang, G.

    2013-12-01

    Long-lived noble-gas isotopes 85Kr (10.8 y), 39Ar (269 y) and 81Kr (229 ky) are ideal tracers for dating environmental samples such as groundwater and ice. Together with 14C, these nuclides can be used to cover the whole range of 100-106 y. Atom Trap Trace Analysis (ATTA) is an emerging method for the analysis of these isotopes at an isotopic abundance level as low as 10^-16 [1,2]. The ATTA instrument built in Hefei, China, can determine the isotopic abundances of 85Kr and 81Kr with typically 5-10% accuracy using krypton gas samples of a few micro-liters (STP) krypton gas [3]. The krypton gas sample can be extracted from several liters of air using a distillation-chromatograph setup with a typical efficiency of 85%, while the air sample can be extracted from groundwater or ices. The typical sample size for ATTA measurement is 100L groundwater or 40Kg ices. One such ATTA beamline can handle about 100 samples per year. [1] Chen, C. Y. et al. Ultrasensitive isotope trace analyses with a magneto-optical trap. Science 286, 1139-1141 (1999). [2] Jiang, W. et al. 39Ar detection at the 10-16 isotopic abundance level with atom trap trace analysis. Phys. Rev. Lett. 106, 103001 (2011). [3] Yang, G. -M. et al. Analysis of 85Kr: a comparison at the 10-14 level using micro-liter samples, Sci. Rep. 3, 1596 (2013). Relative uncertainty of the determined 85Kr abundance by the ATTA-Hefei instrument.

  14. Calibration of Dissolved Noble Gas Mass Spectrometric Measurements by an Air-Water Equilibration System

    NASA Astrophysics Data System (ADS)

    Hillegonds, Darren; Matsumoto, Takuya; Jaklitsch, Manfred; Han, Liang-Feng; Klaus, Philipp; Wassenaar, Leonard; Aggarwal, Pradeep

    2013-04-01

    Precise measurements by mass spectrometry of dissolved noble gases (He, Ar, Ne, Kr, Xe) in water samples require careful calibration against laboratory standards with known concentrations. Currently, air pipettes are used for day-to-day calibrations, making estimation of overall analytical uncertainties for dissolved noble gas measurements in water difficult. Air equilibrated water (AEW) is often used as a matrix-equivalent laboratory standard for dissolved gases in groundwater, because of the well-known and constant fractions of noble gases in the atmosphere. AEW standards, however, are only useful if the temperature and pressure of the gas-water equilibrium can be controlled and measured precisely (i.e., to better than 0.5%); contamination and partial sample degassing must also be prevented during sampling. Here we present the details of a new custom air-water equilibration system which consists of an insulated 600 liter tank filled with deionized water, held isothermally at a precise target temperature (<0.05 °C) through the use of a heat exchanger. The temperature and total dissolved gas of the water in the tank are monitored continually, as are atmospheric pressure and air temperature in the laboratory. Different noble gas concentration standards can be reliably produced by accurately controlling the water temperature of the equilibration system. Equilibration characteristics and reproducibility of this system for production of copper tubes containing known amounts of noble gases will be presented.

  15. Stable structures and electronic properties of 6-atom noble metal clusters using density functional theory

    NASA Astrophysics Data System (ADS)

    Phaisangittisakul, N.; Paiboon, K.; Bovornratanaraks, T.; Pinsook, U.

    2012-08-01

    The 6-atom clusters of group IB noble metals have been investigated theoretically using the density functional calculation with a plane-wave basis (CASTEP). We have calculated their optimized structures, relative cluster's energies, atomic and bonding populations, spectra of the vibrational frequencies, energy gaps between the highest occupied and the lowest unoccupied molecular orbitals, and average polarizabilities per atom. The stable structures we found are planar triangular, pentagonal pyramid, and capped trigonal bipyramid. For the Cu6 and Ag6 cluster, the planar structure energetically competes with the pyramid structure for the ground state. According to the population analyses, the s-d orbital hybridization is explicitly shown to be in association with the corner atoms of the planar structure. We found that the vibrational spectra of the clusters are structural dependent. The average polarizabilities for the planar structure of the Cu6 and Ag6 cluster are quite different from their other stable isomers. In contrast, the polarizabilities are about the same for all stable gold hexamers. Our calculations benefit a reliable geometry identification of the 6-atom noble metal clusters.

  16. Pulmonary hyperpolarized noble gas MRI: recent advances and perspectives in clinical application.

    PubMed

    Liu, Zaiyi; Araki, Tetsuro; Okajima, Yuka; Albert, Mitchell; Hatabu, Hiroto

    2014-07-01

    The invention of hyperpolarized (HP) noble gas MRI using helium-3 ((3)He) or xenon-129 ((129)Xe) has provided a new method to evaluate lung function. Using HP (3)He or (129)Xe for inhalation into the lung air spaces as an MRI contrast agent significantly increases MR signal and makes pulmonary ventilation imaging feasible. This review focuses on important aspects of pulmonary HP noble gas MRI, including the following: (1) functional imaging types, (2) applications for major pulmonary diseases, (3) safety considerations, and (4) future directions. Although it is still challenging to use pulmonary HP noble gas MRI clinically, the technology offers promise for the investigation of the microstructure and function of the lungs. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  17. 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

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

    PubMed

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

    2013-04-01

    Nuclear Magnetic Resonance (NMR) studies with hyperpolarized (hp) noble gases are at an exciting interface between physics, chemistry, materials science and biomedical sciences. This paper intends to provide a brief overview and outlook of magnetic resonance imaging (MRI) with hp noble gases other than hp (3)He. A particular focus are the many intriguing experiments with (129)Xe, some of which have already matured to useful MRI protocols, while others display high potential for future MRI applications. Quite naturally for MRI applications the major usage so far has been for biomedical research but perspectives for engineering and materials science studies are also provided. In addition, the prospects for surface sensitive contrast with hp (83)Kr MRI is discussed. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Perspectives of hyperpolarized noble gas MRI beyond 3He

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    Nuclear Magnetic Resonance (NMR) studies with hyperpolarized (hp) noble gases are at an exciting interface between physics, chemistry, materials science and biomedical sciences. This paper intends to provide a brief overview and outlook of magnetic resonance imaging (MRI) with hp noble gases other than hp 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.

  20. Relationship between recent cave temperatures and noble gas temperatures derived from fluid inclusions of modern soda straw stalactites

    NASA Astrophysics Data System (ADS)

    Palcsu, Laszlo; Papp, Laszlo; Major, Zoltan; Molnar, Mihaly

    2010-05-01

    Recently, strong effort is devoted to establish a new method to derive palaeotemperatures from noble gas (Ne, Ar, Kr, Xe) concentrations dissolved in fluid inclusions of speleothems [1-2]. It has been already shown that the water content of the speleothems can be determined via the water vapour pressure after the water has been released from the carbonate samples and collected in a cold finger and then heated up to room temperature. Additionally, the noble gas contents can be precisely measured with noble gas mass spectrometers. Based on these noble gas concentration data sets, a so-called noble gas temperature (NGT) can be calculated meaning a temperature at which the noble gases have been dissolved in water. To use these NGT's as a palaeoclimate proxy, one of the main questions is how these noble gas temperatures reflect the prevailing cave temperature in which the carbonate has grown. We studied noble gas significances in recent soda straw stalactites from more than ten Central European caves covering a temperature range of 1 to 14 °C. Kluge et al. (2008) has shown the soda straw stalactites might contain less excess air, hence they are more suitable samples to derive NGT's, because noble gas abundances from large air inclusions can mask the temperature information. The 14C ages of these soda straw dripstones were obtained to be recent or at least Holocene ages. Thus one can assume that the cave temperatures during carbonate formation were as same as at present. We measured the water and noble gas contents of numerous carbonate samples from soda straw stalactites and calculated noble gas temperatures by a precision of 1 °C or better. Comparing these temperatures with cave temperatures we obtained that they agree well within the uncertainty of the noble gas temperature determination. Therefore, we can conclude if diffusion of noble gas isotopes does not play a significant role in the carbonate lattice this new tool helps the palaeoclimate community to gain

  1. A membrane inlet mass spectrometry system for noble gases at natural abundances in gas and water samples.

    PubMed

    Visser, Ate; Singleton, Michael J; Hillegonds, Darren J; Velsko, Carol A; Moran, Jean E; Esser, Bradley K

    2013-11-15

    Noble gases dissolved in groundwater can reveal paleotemperatures, recharge conditions, and precise travel times. The collection and analysis of noble gas samples are cumbersome, involving noble gas purification, cryogenic separation and static mass spectrometry. A quicker and more efficient sample analysis method is required for introduced tracer studies and laboratory experiments. A Noble Gas Membrane Inlet Mass Spectrometry (NG-MIMS) system was developed to measure noble gases at natural abundances in gas and water samples. The NG-MIMS system consists of a membrane inlet, a dry-ice water trap, a carbon-dioxide trap, two getters, a gate valve, a turbomolecular pump and a quadrupole mass spectrometer equipped with an electron multiplier. Noble gases isotopes (4)He, (22)Ne, (38)Ar, (84)Kr and (132)Xe are measured every 10 s. The NG-MIMS system can reproduce measurements made on a traditional noble gas mass spectrometer system with precisions of 2%, 8%, 1%, 1% and 3% for He, Ne, Ar, Kr and Xe, respectively. Noble gas concentrations measured in an artificial recharge pond were used to monitor an introduced xenon tracer and to reconstruct temperature variations to within 2 °C. Additional experiments demonstrated the capability to measure noble gases in gas and in water samples, in real time. The NG-MIMS system is capable of providing analyses sufficiently accurate and precise for introduced noble gas tracers at managed aquifer recharge facilities, groundwater fingerprinting based on excess air and noble gas recharge temperature, and field and laboratory studies investigating ebullition and diffusive exchange. Copyright © 2013 John Wiley & Sons, Ltd.

  2. 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.

  3. 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.

  4. 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.

  5. Targets Involved in Cardioprotection by the Non-Anesthetic Noble Gas Helium.

    PubMed

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

    2015-01-01

    Research data from the past decade indicate that noble gases like xenon and helium exert profound cardioprotection when applied before, during or after organ ischemia. Of all noble gases, especially helium, has gained interest in the past years because it does not have an anesthetic "side effect" like xenon, allowing application of this specific gas in numerous clinical ischemia/reperfusion situations. Because helium has several unique characteristics and no hemodynamic side effects, helium could be administered in severely ill patients. Investigations in animals as well as in humans have proven that this noble gas is not completely inert and can induce several biological effects. Though the underlying molecular mechanisms of helium-induced cardiac protection are still not yet fully understood, recently different signaling pathways have been elucidated.

  6. Measuring laser carrier-envelope-phase effects in the noble gases with an atomic hydrogen calibration standard

    NASA Astrophysics Data System (ADS)

    Khurmi, Champak; Wallace, W. C.; Sainadh U, Satya; Ivanov, I. A.; Kheifets, A. S.; Tong, X. M.; Litvinyuk, I. V.; Sang, R. T.; Kielpinski, D.

    2017-07-01

    We present accurate measurements of carrier-envelope-phase effects on ionization of the noble gases with few-cycle laser pulses. The experimental apparatus is calibrated by using atomic hydrogen data to remove any systematic offsets and thereby obtain accurate CEP data on other generally used noble gases such as Ar, Kr, and Xe. Experimental results for H are well supported by exact time-dependent Schrödinger equation theoretical simulations; however, significant differences are observed in the case of the noble gases.

  7. 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

  8. Maximum noble-metal efficiency in catalytic materials: atomically dispersed surface platinum.

    PubMed

    Bruix, Albert; Lykhach, Yaroslava; Matolínová, Iva; Neitzel, Armin; Skála, Tomáš; Tsud, Nataliya; Vorokhta, Mykhailo; Stetsovych, Vitalii; Ševčíková, Klára; Mysliveček, Josef; Fiala, Roman; Václavů, Michal; Prince, Kevin C; Bruyère, Stéphanie; Potin, Valérie; Illas, Francesc; Matolín, Vladimír; Libuda, Jörg; Neyman, Konstantin M

    2014-09-22

    Platinum is the most versatile element in catalysis, but it is rare and its high price limits large-scale applications, for example in fuel-cell technology. Still, conventional catalysts use only a small fraction of the Pt content, that is, those atoms located at the catalyst's surface. To maximize the noble-metal efficiency, the precious metal should be atomically dispersed and exclusively located within the outermost surface layer of the material. Such atomically dispersed Pt surface species can indeed be prepared with exceptionally high stability. Using DFT calculations we identify a specific structural element, a ceria "nanopocket", which binds Pt(2+) so strongly that it withstands sintering and bulk diffusion. On model catalysts we experimentally confirm the theoretically predicted stability, and on real Pt-CeO2 nanocomposites showing high Pt efficiency in fuel-cell catalysis we also identify these anchoring sites.

  9. Cationic noble gas hydrides: a theoretical investigation of dinuclear HNgFNgH+ (Ng = He-Xe).

    PubMed

    Borocci, Stefano; Bronzolino, Nicoletta; Giordani, Maria; Grandinetti, Felice

    2010-07-15

    Theoretical calculations at the B3LYP, MP2, and CCSD(T) levels of theory disclose the conceivable existence of cationic noble gas hydrides containing two Ng atoms. These species have a general formula of HNgFNgH(+) (Ng = He-Xe), and are the cationic counterparts of the neutral HNgF. The optimized geometries, harmonic frequencies, and bonding properties point to ion-dipole complexes between a fluoride anion and two covalent H-Ng(+) cations, best formulated as (H-Ng(+))(2)F(-). The HXeFXeH(+) is also isoelectronic with the recently experimentally observed HXeOXeH (Khriachtchev et al. J. Am. Chem. Soc. 2008, 130, 6114-6118). The resulting HNgFNgH(+) are thermochemically stable with respect to dissociation into HNg(+) + HNgF and HNg(+) + H + Ng + F, but are largely unstable with respect to both the loss of HF (with formation of HNg(+) + Ng) and H(2)F(+) (with formation of two Ng atoms). These decompositions pass through bent transition structures, and only the heaviest HArFArH(+), HKrFKrH(+), and HXeFXeH(+) are protected by energy barriers large enough (ca. 10-15 kcal mol(-1)) to support their conceivable metastability. In line with other series of noble gas compounds, the neon cation HNeFNeH(+) is the least stable among the various HNgFNgH(+).

  10. 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.

  11. 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

  12. Holocene noble gas paleothermometry from springs in the Olympic Mountains, Washington.

    EPA Science Inventory

    Noble gas temperature proxies are examined from 52 springs in the Olympic Mountains, Washington. Groundwater flows from seeps to pooled springs at <0.1 L s-1 - 2.5 L s-1 in the Elwha watershed (≈692 km2). About 85% of sampled springs issue from confined fracture reservoirs preser...

  13. Holocene noble gas paleothermometry from springs in the Olympic Mountains, Washington.

    EPA Science Inventory

    Noble gas temperature proxies are examined from 52 springs in the Olympic Mountains, Washington. Groundwater flows from seeps to pooled springs at <0.1 L s-1 - 2.5 L s-1 in the Elwha watershed (≈692 km2). About 85% of sampled springs issue from confined fracture reservoirs preser...

  14. Isotopic and noble gas geochemistry in geothermal research

    SciTech Connect

    Kennedy, B.M.; DePaolo, D.J.

    1997-12-31

    The objective of this program is to provide, through isotopic analyses of fluids, fluid inclusions, and rocks and minerals coupled with improved methods for geochemical data analysis, needed information regarding sources of geothermal heat and fluids, the spatial distribution of fluid types, subsurface flow, water-rock reaction paths and rates, and the temporal evolution of geothermal systems. Isotopic studies of geothermal fluids have previously been limited to the light stable isotopes of H, C, and O. However, other isotopic systems such as the noble gases (He, Ne, Ar, Kr and Xe) and reactive elements (e.g. B, N, S, Sr and Pb) are complementary and may even be more important in some geothermal systems. The chemistry and isotopic composition of a fluid moving through the crust will change in space and time in response to varying chemical and physical parameters or by mixing with additional fluids. The chemically inert noble gases often see through these variations, making them excellent tracers for heat and fluid sources. Whereas, the isotopic compositions of reactive elements are useful tools in characterizing water-rock interaction and modeling the movement of fluids through a geothermal reservoir.

  15. Experimental determination of noble gas, SF6 and CO2 flow profiles through a porous sandstone

    NASA Astrophysics Data System (ADS)

    Kilgallon, Rachel; Gilfillan, Stuart; Edlmann, Katriona; McDermott, Chris

    2016-04-01

    The noble gases (He, Ne, Ar, Kr and Xe) and SF6 have recently been used as artificial and inherent tracers of CO2 flow and migration from within[1,2] and from geological reservoirs[3]. However, outstanding questions remain, particularly regarding the flow behaviour of the noble gases compared to CO2. Here we present results from specially constructed experimental equipment, which has been used to determine the factors affecting transport of noble gases relative to CO2 in a porous sandstone. The experimental setup consists of a sample loop that can be loaded with a desired gas mixture. This sample can be released as a pulse into a feeder gas stream through a flow cell. The flow cell consists of a 3.6 cm diameter core, which can be of any length. The sample is surrounded by aluminium foil and treated with epoxy resin inside stainless steel tubing. The flow cell is encased by two purpose designed dispersion end plates. Real-time analysis of the arrival peaks of the gases downstream is recorded using a Quadrupole Mass Spectrometer (QMS). For the experiments, a 0.96 m core of Fell Sandstone was selected to represent a porous media. Noble gases and SF6 pulses were flowed through a CO2 carrier gas at five different pressure gradients (10 - 50 kPa) with arrival profiles measured using the QMS. Surprisingly, peak arrival times of He were slower than the other noble gases at each pressure gradient. The differences in peak arrival times between He and other noble gases increased as pressure decreased and the curve profiles for each noble gas differ significantly. The heavier noble gases (Kr and Xe) along with SF6 show a steeper peak rise at initial appearance, but have a longer duration profile than the He curves. Interestingly, the breakthrough curve profiles for both Kr and Xe were similar to SF6 indicating that Kr and Xe could be substituted for SF6, which is a potent greenhouse gas, in tracing applications. In addition, CO2 pulses were passed through a N2 carrier gas. The

  16. Reproducibility and accuracy of noble gas measurements on water samples in the microlitre range.

    PubMed

    Sander, Tim; Marx, Thomas; Engel, Jürgen; Aeschbach-Hertig, Werner

    2014-01-15

    In order to derive meaningful noble gas temperatures (NGTs) from speleothem fluid inclusions, precise and accurate measurements of noble gas concentrations on very small water samples are necessary. To optimise these measurements and their reliability, an investigation of the reproducibility and accuracy of the analytical procedure is essential. Water equilibrated with air under controlled conditions was filled into copper capillaries to produce small (about 1 μL) air-equilibrated water samples (so-called μAEWs). As speleothem samples, the μAEWs were opened in a crusher and the released noble gases analysed with an electron ionisation sector field mass spectrometer run in static mode. For better comparability with speleothem samples, a defined amount of air was added to the noble gases derived from one group of μAEWs. The reproducibility of the experimental procedure was found to be better than 2.2% for all relevant noble gases. Within these uncertainties, the measured noble gas concentrations of μAEWs agree with expectations. The corresponding NGTs reproduce within 0.5°C and deviate by less than 1°C from the equilibration temperature. In the case of air addition, the air to water ratio was determined accurately and, excluding one outlier, the NGTs were determined with a reproducibility and accuracy well below 1°C. The results show that the used measurement procedure is generally suitable to reveal major climatic temperature changes, for which an overall NGT error of less than 1°C is desirable, from very small water samples as obtained from speleothem fluid inclusions. Copyright © 2013 John Wiley & Sons, Ltd.

  17. Characterizing the Noble Gas Isotopic Composition of the Barnett Shale and Strawn Group and Constraining the Source of Stray Gas in the Trinity Aquifer, North-Central Texas.

    PubMed

    Wen, Tao; Castro, M Clara; Nicot, Jean-Philippe; Hall, Chris M; Pinti, Daniele L; Mickler, Patrick; Darvari, Roxana; Larson, Toti

    2017-06-06

    This study presents the complete set of stable noble gases for Barnett Shale and Strawn Group production gas together with stray flowing gas in the Trinity Aquifer, Texas. It places new constraints on the source of this stray gas and further shows that Barnett and Strawn gas have distinct crustal and atmospheric noble gas signatures, allowing clear identification of these two sources. Like stray gas, Strawn gas is significantly more enriched in crustal (4)He*, (21)Ne*, and (40)Ar* than Barnett gas. The similarity of Strawn and stray gas crustal noble gas signatures suggests that the Strawn is the source of stray gas in the Trinity Aquifer. Atmospheric (22)Ne/(36)Ar ratios of stray gas mimic also that of Strawn, further reinforcing the notion that the source of stray gas in this aquifer is the Strawn. While noble gas signatures of Strawn and stray gas are consistent with a single-stage water degassing model, a two-stage oil modified groundwater exsolution fractionation model is required to explain the light atmospheric noble gas signature of Barnett Shale production gas. These distinct Strawn and Barnett noble gas signatures are likely the reflection of distinct evolution histories with Strawn gas being possibly older than that of Barnett Shale.

  18. A noble gas profile across a Hawaiian mantle xenolith: Coexisting accidental and cognate noble gases derived from the lithospheric and asthenospheric mantle beneath Oahu

    NASA Astrophysics Data System (ADS)

    Rocholl, A.; Heusser, E.; Kirsten, T.; Oehm, J.; Richter, H.

    1996-12-01

    A noble gas profile across a garnet pyroxenite xenolith from Salt Lake Crater, Oahu, Hawaii, provides information about the scale and origin of noble gas heterogeneities within such rocks. Variations in both absolute and relative noble gas concentrations are large and comparable to those observed between individual Salt Lake Crater pyroxenite xenoliths. 3He/4He varies from 7.7 to 9.4 times the atmospheric value (Ra) and correlates inversely with 40Ar/36Ar, which ranges between 4100 and 9700. Neon krypton and xenon isotopes are uniform and indistinguishable from air, with the exception of excess 129Xe. Overall, the observed noble gas compositions reflect a derivation from depleted MORB-type mantle sources. The spatial distribution of noble gas signatures within the xenolith and the observed correlation between helium and argon isotopes suggest the presence of two different noble gas components which are trapped in different phases and are unevenly distributed within the xenolith. 40Ar/36Ar and 1/36Ar correlate inversely, indicating that atmospheric contamination is insignificant. Hence, the observed isotopic variations reflect mixing of two mantle-derived noble gas components. Correlations between Hesbnd Ar isotopes and CO2/H2O in different pyroxenites from Salt Lake Crater, including our sample, reveal that the first component is characterized by highly radiogenic helium and argon isotopes and related to abundant secondary CO2-rich fluid inclusions. Given the high diffusivity of He at mantle temperatures (Hart, 1984), the observed helium isotope heterogeneities on a sub-mm scale require that the fluids were introduced concurrently with eruption. This interpretation is supported by the low entrapment depths of fluid inclusions in Salt Lake Crater pyroxenites (<30 km; Murck et al., 1978). This implies that the fluids are genetically related to the host magma itself and reflect its composition. The second noble gas component is interpreted as being magmatic, i

  19. 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.

  20. Theoretical prediction of maximum capacity of C₈₀ and Si₈₀ fullerenes for noble gas storage.

    PubMed

    Mahdavifar, Zabiollah

    2014-11-01

    In this paper, we try to demonstrate that how many helium, neon and argon atoms can be trapped into fullerene cages until the pressure becomes large enough to break the C80 and Si80 frameworks. The maximum number of helium, neon and argon atoms which can be encapsulated into C80 fullerene, is found with 46, 24 and 10 atoms respectively. Having investigated the mechanism of C80 opening, we found that if the number of helium and argon atoms reaches to 50 and 12 respectively, the C-C bonds of C80 are broken and the gas molecules escaped from the fullerene cage. The final optimization geometries of latter complexes are similar to the shopping cart. Therefore, this appearance is named as molecular cart. Moreover, the maximum capacity of Si80 fullerene for encapsulated noble gas atoms is found 95, 56 and 22 for helium, neon and argon atoms correspondingly. It is worth highlighting that the new phenomenon of trapping argon atoms into Si80 cage is observed, when a Si atom randomly added to the center of Ar19@Si80 structures. In this case, the Si-Si bonds of Si80 are broken and two argon atoms will escape from the cage. After that, the framework rebuilds its structure like the initial one. This phenomenon is introduced as molecular cesarean section. The estimated internal pressure of Ng atoms trapped into the fullerene cages is also investigated. Results show that the maximum calculated internal pressure is related to He46@C80 and He95@Si80 structures with 212.3 and 144.1GPa respectively. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Statistical theory of noble-gas crystals and the phenomenon of sublimation

    NASA Astrophysics Data System (ADS)

    Bondarev, V. N.

    2005-05-01

    We propose a consistent (without any fitting parameters) statistical theory of classical noble-gas crystals with pair interaction between atoms. Using the equation for the single-particle distribution function of the statistical system, we demonstrate the existence of an infinite number of exact sum rules for the amplitudes of the space-periodic solutions. Even the first sum rule leads to the solution which turns into the exact one at the absolute zero temperature. For the pair distribution function, we obtained the physically correct solution using the well-known exact relation for the compressibility as the self-consistent condition. As a result, we succeeded in recovering the equation of state of the crystal, and starting from the Lennard-Jones potential with the “gaseous” parameters, we calculated the temperature dependencies of the lattice constant and the isothermal compressibility of the crystal at the sublimation line. These calculations (including the form of the sublimation line itself) agree rather well with the corresponding experimental data for the argon-type media in the “classical” temperature region. The question about the bifurcation of the solutions is considered. Ways to further develop the theory are discussed.

  2. Element distribution and noble gas isotopic abundances in lunar meteorite Allan Hills A81005

    NASA Technical Reports Server (NTRS)

    Kraehenbuehl, U.; Eugster, O.; Niedermann, S.

    1986-01-01

    Antarctic meteorite ALLAN HILLS A81005, an anorthositic breccia, is recognized to be of lunar origin. The noble gases in this meteorite were analyzed and found to be solar-wind implanted gases, whose absolute and relative concentrations are quite similar to those in lunar regolith samples. A sample of this meteorite was obtained for the analysis of the noble gas isotopes, including Kr(81), and for the determination of the elemental abundances. In order to better determine the volume derived from the surface correlated gases, grain size fractions were prepared. The results of the instrumental measurements of the gamma radiation are listed. From the amounts of cosmic ray produced noble gases and respective production rates, the lunar surface residence times were calculated. It was concluded that the lunar surface time is about half a billion years.

  3. Noble Metal Catalysts for Mercury Oxidation in Utility Flue Gas: Gold, Palladium and Platinum Formulations

    SciTech Connect

    Presto, A.A.; Granite, E.J

    2008-07-01

    The use of noble metals as catalysts for mercury oxidation in flue gas remains an area of active study. To date, field studies have focused on gold and palladium catalysts installed at pilot scale. In this article, we introduce bench-scale experimental results for gold, palladium and platinum catalysts tested in realistic simulated flue gas. Our initial results reveal some intriguing characteristics of catalytic mercury oxidation and provide insight for future research into this potentially important process.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    case the known isotopic ratio is measured on different pairs of detectors and the true value of the isotopic ratio of interest can be determined by a specific equation. In noble gas analysis, due to the decay of the ion beam during the measurement as well as the special isotopic systematic of the gases themselves, the cross-calibration of the SEM using these techniques becomes more complex and other methods should be investigated. In this work we present a comparison between different approaches to cross-calibrate multiple SEM's in noble gas analysis in order to evaluate the most suitable and reliable method. References: [1] Mark et al. (2009) Geochem. Geophys. Geosyst. 10, 1-9. [2] Mark et al. (2011) Geochim. Cosmochim. 75, 7494-7501. [3] Phillips and Matchan (2013) Geochimica et Cosmochimica Acta 121, 229-239. [4] Koornneef et al. (2014) Journal of Analytical Atomic Spectrometry 28, 749-754.

  5. Multielectron effects in the photoelectron momentum distribution of noble-gas atoms driven by visible-to-infrared-frequency laser pulses: A time-dependent density-functional-theory approach

    NASA Astrophysics Data System (ADS)

    Murakami, Mitsuko; Zhang, G. P.; Chu, Shih-I.

    2017-05-01

    We present the photoelectron momentum distributions (PMDs) of helium, neon, and argon atoms driven by a linearly polarized, visible (527-nm) or near-infrared (800-nm) laser pulse (20 optical cycles in duration) based on the time-dependent density-functional theory (TDDFT) under the local-density approximation with a self-interaction correction. A set of time-dependent Kohn-Sham equations for all electrons in an atom is numerically solved using the generalized pseudospectral method. An effect of the electron-electron interaction driven by a visible laser field is not recognizable in the helium and neon PMDs except for a reduction of the overall photoelectron yield, but there is a clear difference between the PMDs of an argon atom calculated with the frozen-core approximation and TDDFT, indicating an interference of its M -shell wave functions during the ionization. Furthermore, we find that the PMDs of degenerate p states are well separated in intensity when driven by a near-infrared laser field, so that the single-active-electron approximation can be adopted safely.

  6. The Noble Gas Record of Gas-Water Phase Interaction in the Tight-Gas-Sand Reservoirs of the Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Ballentine, C. J.; Zhou, Z.; Harris, N. B.

    2015-12-01

    The mass of hydrocarbons that have migrated through tight-gas-sandstone systems before the permeability reduces to trap the hydrocarbon gases provides critical information in the hydrocarbon potential analysis of a basin. The noble gas content (Ne, Ar, Kr, Xe) of the groundwater has a unique isotopic and elemental composition. As gas migrates through the water column, the groundwater-derived noble gases partition into the hydrocarbon phase. Determination of the noble gases in the produced hydrocarbon phase then provides a record of the type of interaction (simple phase equilibrium or open system Rayleigh fractionation). The tight-gas-sand reservoirs of the Rocky Mountains represent one of the most significant gas resources in the United States. The producing reservoirs are generally developed in low permeability (averaging <0.1mD) Upper Cretaceous fluvial to marginal marine sandstones and commonly form isolated overpressured reservoir bodies encased in even lower permeability muddy sediments. We present noble gas data from producing fields in the Greater Green River Basin, Wyoming; the the Piceance Basin, Colorado; and in the Uinta Basin, Utah. The data is consistent from all three basins. We show how in each basin the noble gases record open system gas migration through a water column at maximum basin burial. The data within an open system model indicates that the gas now in-place represents the last ~10% of hydrocarbon gas to have passed through the water column, most likely prior to permeability closedown.

  7. NMR spectroscopic study of noble gas binding into the engineered cavity of HPr(I14A) from Staphylococcus carnosus.

    PubMed

    Nisius, Lydia; Stadler, Max; Kalbitzer, Hans Robert; Brunner, Eike

    2005-09-29

    Xenon binding into preexisting cavities in proteins is a well-known phenomenon. Here we investigate the interaction of helium, neon, and argon with hydrophobic cavities in proteins by NMR spectroscopy. 1H and 15N chemical shifts of the I14A mutant of the histidine-containing phosphocarrier protein (HPr(I14A)) from Staphylococcus carnosus are analyzed by chemical shift mapping. Total noble gas induced chemical shifts, Delta, are calculated and compared with the corresponding values obtained using xenon as a probe atom. This comparison reveals that the same cavity is detected with both argon and xenon. Measurements using the smaller noble gases helium and neon as probe atoms do not result in comparable effects. The dependence of amide proton and nitrogen chemical shifts on the argon concentration is investigated in the range from 10 mM up to 158 mM. The average dissociation constant for argon binding into the engineered cavity is determined to be about 90 mM.

  8. Fluorinated noble-gas cyanides FKrCN, FXeCN, and FXeNC

    SciTech Connect

    Zhu, Cheng; Räsänen, Markku; Khriachtchev, Leonid

    2015-08-21

    We report on three new noble-gas molecules, FKrCN, FXeCN, and FXeNC, prepared in low-temperature Kr and Xe matrices. These molecules are made by UV photolysis of FCN in the matrices and subsequent thermal annealing. The FCN precursor is produced by deposition of the matrix gas containing (FCN){sub 3} through a microwave discharge. The new noble-gas molecules are assigned with the help of quantum chemical calculations at the MP2(full) and CCSD(T) levels of theory. Similar Ar compounds (FArCN and FArNC) as well as FKrNC are not found in these experiments, which is in agreement with the calculated energetics.

  9. ORIGIN OF THERMAL FLUIDS AT LASSEN VOLCANIC NATIONAL PARK: EVIDENCE FROM NOBLE AND REACTIVE GAS ABUNDANCES.

    USGS Publications Warehouse

    Truesdell, Alfred H.; Mazor, Emanuel; Nehring, Nancy L.

    1983-01-01

    Thermal fluid discharges at Lassen are dominated by high-altitude fumaroles and acid-sulfate hot springs in the Park, and lower altitude, neutral, high-chloride hot springs in Mill Valley 7-10 km to the south. The interrelations of these fluids have been studied by noble and reactive gas analyses. Atmospheric noble gas (ANG) contents of superheated fumaroles are similar to those of air-saturated recharge water (ASW) at 5 degree C and 2500-m elevation. Low-elevation, high-chloride, hot-spring waters are highly depleted in ANG, relative to the ASW. The surface temperatures and gas chemistry of the fumaroles and hot springs suggest that steam originating from partial to near-complete vaporization of liquid from a boiling, high-chloride, hot water aquifer is decompressed adiabatically, and more or less mixed with shallow groundwater to form superheated and drowned fumaroles within the Park. Refs.

  10. 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

  11. 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).

  12. Nature of sonoluminescence: noble gas radiation excited by hot electrons in cold water

    PubMed

    Garcia; Levanyuk; Osipov

    2000-08-01

    It was proposed before that single bubble sonoluminescence (SBSL) may be caused by strong electric fields occurring in water near the surface of collapsing gas bubbles because of the flexoelectric effect involving polarization resulting from a gradient of pressure. Here we show that these fields can indeed provoke dynamic electric breakdown in a micron-size region near the bubble and consider the scenario of the SBSL. The scenario is (i) at the last stage of incomplete collapse of the bubble, the gradient of pressure in water near the bubble surface has such a value and a sign that the electric field arising from the flexoelectric effect exceeds the threshold field of the dynamic electrical breakdown of water and is directed to the bubble center; (ii) mobile electrons are generated because of thermal ionization of water molecules near the bubble surface; (iii) these electrons are accelerated in "cold" water by the strong electric fields; (iv) these hot electrons transfer noble gas atoms dissolved in water to high-energy excited states and optical transitions between these states produce SBSL UV flashes in the transparency window of water; (v) the breakdown can be repeated several times and the power and duration of the UV flash are determined by the multiplicity of the breakdowns. The SBSL spectrum is found to resemble a black-body spectrum where temperature is given by the effective temperature of the hot electrons. The pulse energy and some other characteristics of the SBSL are found to be in agreement with the experimental data when realistic estimates are made.

  13. Long Term Field Calibration of the Noble Gas Temperature System in a Shallow Unconfined Pleistocene Aquifer

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

    Noble gas temperatures (NGTs) are a potentially powerful tool for paleoclimate reconstruction on continents, but the assumptions underlying the technique have not been widely tested for aquifers in colder climates. In a recent study of NGTs from S. Michigan groundwater, Ma et al. (2004) found significant NGT variation over time, but apparently modern water yielded NGTs that were ~ 3 ° C or more below that expected from the local mean annual air temperature (MAAT). For nearly a year, we have monitored NGTs and stable isotopes at a shallow water well in the glacial drift that recharges the aquifer studied by Ma et al. (2004). Initial results are in press (Hall et al., 2005) and they confirm that modern NGTs measured from Oct. to Jul. are typically 5-6°C, instead of the MAAT of 9.1°C. Measured water temperatures during sampling are within 1-2°C of MAAT. Stable isotopic analyses of local snow and rain water suggest that the groundwater is a mixture of these two end member components. Short term variations in well pH and stable isotope ratios confirm that the groundwater is indeed modern, but initial noble gas results did not show similar variations. Ground ice noble gas concentrations are very low, with the exception of He, which is enriched, with 3He/4He equal to the air value. All early noble gas concentrations in groundwater were too high for the MAAT, including both He isotopes which had 3He/4He about 1.3 times air. Measured groundwater excess He values are compatible with 4He influx from below and tritium decay for ~ 30 yr. None of the standard NGT interpretational models adequately account for the complete data set, without modifications to normal assumptions. The most recent Aug. 2005 data after a very rainy Jul. does show a dramatic rise in NGT, with typical excess He, suggesting that noble gas concentrations acquired high in the unsaturated zone can persist and mix with those below the water table. This implies that dynamic effects may be very important in

  14. Effects of halogens on interactions between a reduced TiO2 (110) surface and noble metal atoms: A DFT study

    NASA Astrophysics Data System (ADS)

    Tada, Kohei; Koga, Hiroaki; Hayashi, Akihide; Kondo, Yudai; Kawakami, Takashi; Yamanaka, Shusuke; Okumura, Mitsutaka

    2017-07-01

    Using DFT calculation, we investigate the effects of halogens on the interactions between rutile TiO2 (110) and noble metal atoms (Au, Ag, Cu, Pt, and Pd). Fluorine, chlorine, and bromine atoms occupy the oxygen defect sites of TiO2, decreasing the stability of noble metal atoms on the surface. This decrease occurs because the halogens inhibit electron transfer from TiO2 to the noble metal atoms; the electron transfer from reduced TiO2 to the noble metal atom stabilizes the noble metal atom adsorption. In contrast, iodine strengthens the interactions between TiO2 and some noble metal atoms, namely Ag and Cu. This stabilization occurs because of the covalent interaction between iodine-doped TiO2 and the noble metal atom. Therefore, the stabilization is explained well by chemical hardness. This result suggests that iodine-doping of a TiO2 surface would be an effective method for the preparation of highly stabilized noble metal clusters.

  15. Investigating noble gas mixtures for use in TPCs

    NASA Astrophysics Data System (ADS)

    Jungbluth, Anna

    2017-01-01

    MITPC is a gas-based time projection chamber used for detecting fast, MeV-scale neutrons. MITPC relies on a CCD camera and the TPC (time projection chamber) technique to visualize and reconstruct tracks of neutron-induced nuclear recoils within a chosen gas. The standard version of the detector uses a mixture of 600 torr gas composed of 87.5% helium-4 and and 12.5% tetrafluoromethane (CF4) for precise measurements of the energy and direction of neutron-induced nuclear recoils. Previous studies demonstrated advantages of using neon as a replacement gas for helium-4. This talk will present a discussion of studies performed with helium and neon, as well as argon and krypton as primary neutron targets in the gas mixture with CF4.

  16. Noble gases solubility models of hydrocarbon charge mechanism in the Sleipner Vest gas field

    NASA Astrophysics Data System (ADS)

    Barry, P. H.; Lawson, M.; Meurer, W. P.; Warr, O.; Mabry, J. C.; Byrne, D. J.; Ballentine, C. J.

    2016-12-01

    Noble gases are chemically inert and variably soluble in crustal fluids. They are primarily introduced into hydrocarbon reservoirs through exchange with formation waters, and can be used to assess migration pathways and mechanisms, as well as reservoir storage conditions. Of particular interest is the role groundwater plays in hydrocarbon transport, which is reflected in hydrocarbon-water volume ratios. Here, we present compositional, stable isotope and noble gas isotope and abundance data from the Sleipner Vest field, in the Norwegian North Sea. Sleipner Vest gases are generated from primary cracking of kerogen and the thermal cracking of oil. Gas was emplaced into the Sleipner Vest from the south and subsequently migrated to the east, filling and spilling into the Sleipner Ost fields. Gases principally consist of hydrocarbons (83-93%), CO2 (5.4-15.3%) and N2 (0.6-0.9%), as well as trace concentrations of noble gases. Helium isotopes (3He/4He) are predominantly radiogenic and range from 0.065 to 0.116 RA; reported relative to air (RA = 1.4 × 10-6; Clarke et al., 1976; Sano et al., 1988), showing predominantly (>98%) crustal contributions, consistent with Ne (20Ne/22Ne from 9.70 to 9.91; 21Ne/22Ne from 0.0290 to 0.0344) and Ar isotopes (40Ar/36Ar from 315 to 489). Air-derived noble gas isotopes (20Ne, 36Ar, 84Kr, 132Xe) are introduced into the hydrocarbon system by direct exchange with air-saturated water (ASW). The distribution of air-derived noble gas species are controlled by phase partitioning processes; in that they preferentially partition into the gas (i.e., methane) phase, due to their low solubilities in fluids. Therefore, the extent of exchange between hydrocarbon phases and formation waters - that have previously equilibrated with the atmosphere - can be determined by investigating air-derived noble gas species. We utilize both elemental ratios to address process (i.e., open vs. closed system) and concentrations to quantify the extent of hydrocarbon

  17. New noble gas data of primitive and differentiated achondrites including Northwest Africa 011 and Tafassasset

    NASA Astrophysics Data System (ADS)

    Patzer, A.; Schultz, L.; Franke, L.

    2003-10-01

    This work reports on the noble gas inventory of 3 new acapulcoites, 3 brachinites, 2 new eucrites from the Dar al Gani region in Libya, the unique achondrite Dar al Gani (DaG) 896 from the same locality, the new eucrite-like achondrite Northwest Africa (NWA) 011, and the controversial sample Tafassasset. We determined cosmic ray exposure and gas retention ages, evaluated shielding conditions, and discuss the trapped noble gas component of the specimens. All exposure ages are within the known range of stony meteorites and partly confirm previously established age clusters. Shielding conditions vary, suggesting substantial shielding for all 3 brachinites and Tafassasset. We cannot exclude, however, that the Mg-rich composition of brachinites simply simulates heavy shielding. Regarding the trapped component, we found Q-like compositions only for the acapulcoite Thiel Mountains (TIL) 99002. The brachinite Elephant Moraine (EET) 99402 yields a high, subsolar 36Ar/ 132Xe ratio of ~400 along with a slightly elevated 84Kr/132Xe ratio, indicating minor atmospheric contamination. All the other samples, particularly the eucrite DaG 983, are characterized by clearly elevated Ar/Kr/Xe ratios due to significant terrestrial alteration. Tafassasset exhibits noble gas parameters that are different from those of CR chondrites, including a relatively high cosmic ray exposure age, the absence of a solar component, low 132Xe concentrations, a low trapped 36Ar/132Xe ratio of ~30, and a noticeable amount of radiogenic 129Xe. Similar attributes have been observed for some primitive achondrites. These attributes are also consistent with the metamorphic character of the sample. We, therefore, consider Tafassasset's noble gas record to be inconclusive as to its classification (primitive achondrite versus metamorphosed CR chondrite).

  18. Stability of noble-gas-bound SiH₃⁺ clusters.

    PubMed

    Pan, Sudip; Moreno, Diego; Merino, Gabriel; Chattaraj, Pratim K

    2014-11-10

    The stability of noble gas (Ng)-bound SiH3(+) clusters is explored by ab initio computations. Owing to a high positive charge (+1.53 e(-)), the Si center of SiH3(+) can bind two Ng atoms. However, the Si-Ng dissociation energy for the first Ng atom is considerably larger than that for the second one. As we go down group 18, the dissociation energy gradually increases, and the largest value is observed for the case of Rn. For NgSiH3(+) clusters, the Ar-Rn dissociation processes are endergonic at room temperature. For He and Ne, a much lower temperature is required for it to be viable. The formation of Ng2SiH3(+) clusters is also feasible, particularly for the heavier members and at low temperature. To shed light on the nature of Si-Ng bonding, natural population analysis, Wiberg bond indices computations, electron-density analysis, and energy-decomposition analysis were performed. Electron transfer from the Ng centers to the electropositive Si center occurs only to a small extent for the lighter Ng atoms and to a somewhat greater extent for the heavier analogues. The Si-Xe/Rn bonds can be termed covalent bonds, whereas the Si-He/Ne bonds are noncovalent. The Si-Ar/Kr bonds possess some degree of covalent character, as they are borderline cases. Contributions from polarization and charge transfer and exchange are key terms in forming Si-Ng bonds. We also studied the effect of substituting the H atoms of SiH3(+) by halide groups (-X) on the Ng binding ability. SiF3(+) showed enhanced Ng binding ability, whereas SiCl3(+) and SiBr3(+) showed a lower ability to bind Ng than SiH3(+). A compromise originates from the dual play of the inductive effect of the -X groups and X→Si π backbonding (p(z)-p(z) interaction).

  19. 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.

  20. Quantum-chemical modeling of boron and noble gas dopants in silicon

    NASA Technical Reports Server (NTRS)

    Aronowitz, S.

    1983-01-01

    The electron effects of the presence of boron and noble gas dopants in a model silicon lattice were investigated using a self-consistent charge extended Hueckel program. The extent of electronic interaction of the noble gas with the lattice is given by: Kr greater than Ar greater than Ne. Theoretically, boron diffusion in the presence of neon, argon or krypton was examined using a self-consistent charge extended Hueckel program. The net energy of interaction between boron and neon is strongly repulsive while argon-boron exhibits a region of relative stability; krypton exhibits behavior similar to argon though no region of stability was found for the range of separations used in the calculations. Finally, it is noted, from the relative energy of the topmost filled molecular orbital associated with boron (in an interstitial position), that activation of the boron does not require boron movement but can be accomplished by indirect transitions.

  1. 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.

  2. 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.

  3. Microwrinkle structures on refractory metal surfaces irradiated with noble gas plasma species

    NASA Astrophysics Data System (ADS)

    Takamura, S.; Uesugi, Y.; Ito, A. M.; Yajima, M.; Yamada, K.; Maenaka, S.; Fujita, K.

    2017-08-01

    Microwrinkle structures with a pitch of less than 100 nm and up to 600 nm on refractory metals like tungsten (W) and molybdenum, which are irradiated by noble gas ions such as neon and helium, have been studied systematically. The wrinkle formation mechanism is thought to be a buckling of the hard surface layer supported by the soft elastic substrate, which is induced by a penetration of noble gas species from the irradiated surface. Microwrinkle forms on this structure under lateral compressive strain/stress fields coming from thermal constriction on the way to substrate cooling. Such a process should be anticipated when walls in a fusion reactor are attacked by heat pulses such as edge localized modes and/or vertical displacement events, and therefore might be an initial stage of W surface damage.

  4. Quantum-chemical modeling of boron and noble gas dopants in silicon

    NASA Technical Reports Server (NTRS)

    Aronowitz, S.

    1983-01-01

    The electron effects of the presence of boron and noble gas dopants in a model silicon lattice were investigated using a self-consistent charge extended Hueckel program. The extent of electronic interaction of the noble gas with the lattice is given by: Kr greater than Ar greater than Ne. Theoretically, boron diffusion in the presence of neon, argon or krypton was examined using a self-consistent charge extended Hueckel program. The net energy of interaction between boron and neon is strongly repulsive while argon-boron exhibits a region of relative stability; krypton exhibits behavior similar to argon though no region of stability was found for the range of separations used in the calculations. Finally, it is noted, from the relative energy of the topmost filled molecular orbital associated with boron (in an interstitial position), that activation of the boron does not require boron movement but can be accomplished by indirect transitions.

  5. Coulomb explosion in dicationic noble gas clusters: A genetic algorithm-based approach to critical size estimation for the suppression of Coulomb explosion and prediction of dissociation channels

    NASA Astrophysics Data System (ADS)

    Nandy, Subhajit; Chaudhury, Pinaki; Bhattacharyya, S. P.

    2010-06-01

    We present a genetic algorithm based investigation of structural fragmentation in dicationic noble gas clusters, Arn+2, Krn+2, and Xen+2, where n denotes the size of the cluster. Dications are predicted to be stable above a threshold size of the cluster when positive charges are assumed to remain localized on two noble gas atoms and the Lennard-Jones potential along with bare Coulomb and ion-induced dipole interactions are taken into account for describing the potential energy surface. Our cutoff values are close to those obtained experimentally [P. Scheier and T. D. Mark, J. Chem. Phys. 11, 3056 (1987)] and theoretically [J. G. Gay and B. J. Berne, Phys. Rev. Lett. 49, 194 (1982)]. When the charges are allowed to be equally distributed over four noble gas atoms in the cluster and the nonpolarization interaction terms are allowed to remain unchanged, our method successfully identifies the size threshold for stability as well as the nature of the channels of dissociation as function of cluster size. In Arn2+, for example, fissionlike fragmentation is predicted for n =55 while for n =43, the predicted outcome is nonfission fragmentation in complete agreement with earlier work [Golberg et al., J. Chem. Phys. 100, 8277 (1994)].

  6. 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

  7. Noble Gas Plasmas with Metallic Conductivity: A New Light Source from a New State of Matter

    DTIC Science & Technology

    2015-11-01

    Noble Gas Plasmas with Metallic Conductivity: A New Light Source from a New State of Matter Dense plasmas form a non-ideal, correlated state. We...New Light Source from a New State of Matter Report Title Dense plasmas form a non-ideal, correlated state. We have recreated the plasma inside sono...light, Applied Physics Letters, (12 2014): 223501. doi: A. Bataller, B. Kappus, C. Camara, S. Putterman. Collision Time Measurements in a

  8. A review of noble gas geochemistry in relation to early Earth history

    NASA Technical Reports Server (NTRS)

    Kurz, M. D.

    1985-01-01

    One of the most fundamental noble gas constraints on early Earth history is derived from isotopic differences in (129)Xe/(130)Xe between various terrestrial materials. The short half life (17 m.y.) of extinct (129I, parent of (129)Xe, means that these differences must have been produced within the first 100 m.y. after terrestrial accretion. The identification of large anomalies in (129)Xe/(130)Xe in mid ocean ridge basalts (MORB), with respect to atmospheric xenon, suggests that the atmosphere and upper mantle have remained separate since that time. This alone is a very strong argument for early catastrophic degassing, which would be consistent with an early fractionation resulting in core formation. However, noble gas isotopic systematics of oceanic basalts show that the mantle cannot necessarily be regarded as a homogeneous system, since there are significant variations in (3)He/(4)He, (40)Ar/(36)Ar, and (129)Xe/(130)Xe. Therefore, the early degassing cannot be considered to have acted on the whole mantle. The specific mechanisms of degassing, in particular the thickness and growth of the early crust, is an important variable in understanding present day noble gas inventories. Another constraint can be obtained from rocks that are thought to be derived from near the lithosphere asthenosphere boundary: ultramafic xenoliths.

  9. Theoretical study of icosahedral closo-borane, -alane, and -gallane dianions (A(12)H(12)(2-); A = B, Al, Ga) with endohedral noble gas atoms (Ng = He, Ne, Ar, and Kr) and their lithium salts (Li[Ng@A(12)H(12)](-) and Li(2)[Ng@A(12)H(12)]).

    PubMed

    Charkin, O P; Klimenko, N M; Moran, D; Mebel, A M; Charkin, D O; Schleyer, P R

    2001-12-31

    Geometries, energies, vibrational frequencies, and magnetic properties have been computed at the B3LYP level with the 6-31G and 6-311+G basis sets for a family of endohedral closo-boranes, -alanes, and -gallanes Ng@A(12)H(12)(2-) with noble gas atoms (Ng) located in the centers of icosahedral [B(12)], [Al(12)], and [Ga(12)] clusters. The endohedral structures of most of the systems are minima lying above separated Ng + A(12)H(12)(2-) by 166 (He@B(12)H(12)(2-)) and 403 (Ne@B(12)H(12)(2-)) kcal/mol for boranes; 29 (He@Al(12)H(12)(2-)), 63 (Ne@Al(12)H(12)(2-)), 154 (Ar@Al(12)H(12)(2-)), and 189 (Kr@Al(12)H(12)(2-)) kcal/mol for alanes; and 39 (He@Ga(12)H(12)(2-)), 71 (Ne@Ga(12)H(12)(2-)), and 213 (Ar@Ga(12)H(12)(2-)) kcal/mol for gallanes. Three types of transition states are found for the exit of Ng from a cage: via an edge (TS-1), through a face (TS-2), and via a more extensive deformation through a pentagonal cage "neck" (TS-3). The most favorable exit path depends on the rigidity of the cage, the exothermicity of the dissociation, and the relationship between the size of the internal cavity of the cage and the Ng atomic radius. Ng exit via TS-3 is preferred for He@Al(12)H(12)(2-), Ne@Al(12)H(12)(2-), He@Ga(12)H(12)(2-), Ne@Ga(12)H(12)(2-), Ar@Al(12)H(12)(2), and Kr@Al(12)H(12)(2-). Helium exits via a cage edge (TS-1) for He@B(12)H(12)(2-), while for Ne@B(12)H(12)(2-) the neon exits via a triangular face (TS-2). Exit barriers (H(exit)(double dagger)) are high enough (30-60 kcal/mol) for all helium clusters and for Ne@Al(12)H(12)(2-) and Ne@Ga(12)H(12)(2-) to ensure the kinetic stability of these systems. The barriers for Ar@Al(12)H(12)(2-) and Kr@Al(12)H(12)(2-) decrease to 10-15 kcal/mol, while Ne@B(12)H(12)(2-) has a very low exit barrier and is not expected to be stable kinetically. There is a linear dependence of Ng@A(12)H(12)(2-) cage size on the Ng atomic radii; that is, the heavier Ng atoms "bulge" the cages. Nucleus independent chemical shifts (NICS

  10. Nano bubbles in liquid of a noble-gas mixture.

    PubMed

    Yamamoto, Takenori; Ohnishi, Shuhei

    2010-02-07

    Large-scale molecular dynamics (MD) simulations with over one million atoms are used to investigate nano bubbles in Ar-Ne liquid. The simulations demonstrate cavitations in the stretched liquid, and bubble creation and collapse. We find that a small cavity created in the stretched liquid spontaneously transforms into a nano bubble with the homogeneous vapor region. The equilibrium spherical bubble of 11.4 nm in radius is obtained after the long-time MD run. The surface tension of the nano bubble is found to be larger than that of the flat surface.

  11. 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.

  12. Calculating Subsurface Nucleonic Production of Noble Gas Nuclides: Implications on Crustal and Mantle K, Th, U Abundances

    NASA Astrophysics Data System (ADS)

    Sramek, O.; McDonough, W. F.; Mukhopadhyay, S.; Stevens, L.; Siegel, J.

    2013-12-01

    While atmospheric concentration of some noble gas nuclides is controlled by their cosmogenic production (e.g., 39Ar), nucleonic production dominates in subsurface environments. Nucleogenic production rates, which involve alpha-induced reactions, depend on Th and U abundances in the source rock. Production rates of 39Ar and 40Ar scale with K abundance in the source. Consequently, observed isotopic ratio of noble gas in crustal fluids and mantle-derived lavas can be compared to calculated predictions in order to constrain heat producing element abundances in the source rock. In particular, 39Ar/40Ar, 39Ar/21Ne, and 40Ar/21Ne inform us about U+Th abundance, K abundance, and K/U ratio. We calculate subsurface production rates for these nuclides for various assumed rock compositions. A discrepancy in existing evaluations of 39Ar production rates is noted. While Mei et al. (2010) predict a production rate of 5 atoms of 39Ar per kg per year for a K=2 %, Th=5 ppm, U=2 ppm (by weight) rock, Yokochi et al. (2012) evaluate 39Ar production rate, in number of atoms / (kg yr), at 24, and Yokochi et al. (2013) results range between 50-80. Efforts are underway to understand these differences. Experimental methods of 39Ar counting have advanced significantly in recent years, a development driven to large extent by the needs of experimental particle physics community in their search for dark matter using argon-based WIMP detectors. Measurement techniques now allow determination of 39Ar/40Ar ratios in crustal rocks and are approaching the detectability of 39Ar/40Ar ratio predicted for a mantle source. We discuss how the noble gas ratio measurements can be harnessed to gain insight into source rock's abundances of heat producing elements including mantle K/U ratio. Mei, D.-M. et al., 2010. Phys. Rev. C 81, 055802, doi:10.1103/PhysRevC.81.055802 Yokochi, R. et al., 2012. Geochim. Cosmochim. Acta 88, 19-26, doi:10.1016/j.gca.2012.04.034 Yokochi, R. et al., 2013. Chem. Geol. 339, 43

  13. The noble gas geochemistry of natural CO 2 gas reservoirs from the Colorado Plateau and Rocky Mountain provinces, USA

    NASA Astrophysics Data System (ADS)

    Gilfillan, Stuart M. V.; Ballentine, Chris J.; Holland, Greg; Blagburn, Dave; Lollar, Barbara Sherwood; Stevens, Scott; Schoell, Martin; Cassidy, Martin

    2008-02-01

    Identification of the source of CO 2 in natural reservoirs and development of physical models to account for the migration and interaction of this CO 2 with the groundwater is essential for developing a quantitative understanding of the long term storage potential of CO 2 in the subsurface. We present the results of 57 noble gas determinations in CO 2 rich fields (>82%) from three natural reservoirs to the east of the Colorado Plateau uplift province, USA (Bravo Dome, NM., Sheep Mountain, CO. and McCallum Dome, CO.), and from two reservoirs from within the uplift area (St. John's Dome, AZ., and McElmo Dome, CO.). We demonstrate that all fields have CO 2/ 3He ratios consistent with a dominantly magmatic source. The most recent volcanics in the province date from 8 to 10 ka and are associated with the Bravo Dome field. The oldest magmatic activity dates from 42 to 70 Ma and is associated with the McElmo Dome field, located in the tectonically stable centre of the Colorado Plateau: CO 2 can be stored within the subsurface on a millennia timescale. The manner and extent of contact of the CO 2 phase with the groundwater system is a critical parameter in using these systems as natural analogues for geological storage of anthropogenic CO 2. We show that coherent fractionation of groundwater 20Ne/ 36Ar with crustal radiogenic noble gases ( 4He, 21Ne, 40Ar) is explained by a two stage re-dissolution model: Stage 1: Magmatic CO 2 injection into the groundwater system strips dissolved air-derived noble gases (ASW) and accumulated crustal/radiogenic noble gas by CO 2/water phase partitioning. The CO 2 containing the groundwater stripped gases provides the first reservoir fluid charge. Subsequent charges of CO 2 provide no more ASW or crustal noble gases, and serve only to dilute the original ASW and crustal noble gas rich CO 2. Reservoir scale preservation of concentration gradients in ASW-derived noble gases thus provide CO 2 filling direction. This is seen in the Bravo Dome

  14. The coupling between translation and rotation for monomeric water in noble gas matrices.

    PubMed

    Ceponkus, J; Uvdal, P; Nelander, B

    2013-06-28

    The rotation of water in noble gas matrices has been studied. It is shown that the rotation-translation coupling model of Friedmann and Kimel predicts rotation line spacings, which are close to the experimental observations for H2O, D2O, and HDO, when gas phase rotation constants are used. The model gives intensity estimates in reasonable agreement with the observations for the local oscillator bands, which accompany the rotation spectrum. It also predicts the intensity variations in the bending region of H2O between neon, argon, and krypton matrices.

  15. 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.

  16. 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.

  17. Characterisation of Q-gases and other noble gas components in the Murchison meteorite

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    Noble gases in several HF/HCl resistant residues of the CM2 chondrite Murchison were measured by closed-system stepped etching, in order to study the planetary gases in their major carrier 'Q'-an ill-defined minor phase, perhaps merely a set of adsorption sites. Neon, Ar, Kr, Xe, and probably also He in 'Q' of Murchison have the same isotopic and nearly the same elemental abundances as their counterparts in Allende (CV3). The isotopic composition of Ne-Q is consistent with mass-dependent fractionation of either solar wind Ne or Ne from solar energetic particles. Unlike Allende, Murchison during HNO3 attack release, besides Q-gases, large amounts of two other Ne-components, Ne-E and Ne-A3, a third subcomponent of Ne-A. This work confirms that Q-gases of well-defined composition were an important noble gas component in the early solar system an are now found in various classes of meteorites, such as carbonaceous chondrites, ureilites, and ordinary chondrites. Ne-Q may have played a role in the formation of noble gas reservoirs in terrestrial planets.

  18. Explaining the Noble Gas Content of the Planets: Theoretical Models for Argon-Trapping by Amorphous Ices in the Solar Nebula

    NASA Astrophysics Data System (ADS)

    Sanders, C. B.; Ciesla, F.

    2014-12-01

    The composition of planets in the modern solar system can be traced to the chemistry and physics of the solar nebula, the diffuse disk of gas and dust that surrounded the young sun immediately after its formation. Materials such as the noble gases were too volatile to be chemically incorporated by planetary embryos. Instead, it is likely that they were trapped physically and transported to the inner planets by migrating comets and planetesimals. One trapping mechanism under consideration is the capture of noble gas atoms in amorphous ices on the surface of cold grains. We created a simple numerical model to explore this mechanism, using argon as a representative volatile gas. We have demonstrated that our model reproduces experimental trapping efficiencies (ratio of the volatile atoms to water molecules in the deposited ice) when we constrain the binding energy of our representative volatile to 3500-5500K and the sticking efficiency of volatile atoms to 0.004x gas phase water pressure. Binding energy and sticking efficiency are poorly understood for most volatile substances, but this study finds that they are among the most critical when predicting the trapping of volatiles in the physical world. Constraining these parameters under nebular conditions will allow us to evaluate how much argon could have been trapped in nebular ices and ultimately assess the role of amorphous ice trapping in the origin of planetary volatiles.

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

    NASA Astrophysics Data System (ADS)

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

    1983-06-01

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

  20. International comparison CCQM-K113—noble gas mixture

    NASA Astrophysics Data System (ADS)

    Lim, Jeong Sik; Lee, Jinbok; Moon, Dongmin; Tshilongo, James; Qiao, Han; Shuguo, Hu; Tiqiang, Zhang; Kelley, Michael E.; Rhoderick, George C.; Konopelko, L. A.; Kolobova, A. V.; Vasserman, I. I.; Zavyalov, S. V.; Gromova, E. V.; Efremova, O. V.

    2017-01-01

    Noble gases are one of the key elements used in the various processes of the bulbs industry, automotive industry, space industry, lasers industry, display industry as well as the semiconductor industry. Considering continuous growth, the provision of a reliable standard is required for those industries to improve their productivity. In this report, a result of the key comparison, CCQM-K113: noble gas mixture, is presented. Nominal amount-of-substance fractions of argon, neon, krypton, and xenon in helium are 20, 10, 2, and 1 cmol/mol, respectively. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    Previous work showed that the H3e(n ,tp) reaction in a cell of H3e at atmospheric pressure generated tens of far-ultraviolet photons per reacted neutron. Here we report amplification of that signal by factors of 1000 and more when noble gases are added to the cell. Calibrated filter-detector measurements show that this large signal is due to noble gas excimer emissions and that the nuclear reaction energy is converted to far-ultraviolet radiation with efficiencies of up to 30%. The results have been placed on an absolute scale through calibrations at the NIST SURF III synchrotron. They suggest possibilities for high-efficiency neutron detectors as an alternative to existing proportional counters.

  2. 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

  3. Reactivity and regioselectivity of noble gas endohedral fullerenes Ng@C(60) and Ng(2)@C(60) (Ng=He-Xe).

    PubMed

    Osuna, Sílvia; Swart, Marcel; Solà, Miquel

    2009-12-07

    Recently, it was shown that genuine Ng-Ng chemical bonds are present in the endohedral fullerenes Ng(2)@C(60) in the case of Ng=Xe, while it is more debatable whether a chemical bond exist for Ng=Ar and Kr. The lighter homologues with helium and neon are weakly bonded van der Waals complexes. The presence of a noble gas dimer inside the cage is expected to modify the exohedral reactivity of the C(60) cage with respect to that of free C(60). To investigate the impact of encapsulated diatomic noble gas molecules on the chemical reactivity of C(60), we analyzed the thermodynamics and the kinetics of [4+2] Diels-Alder cycloaddition of 1,3-cis-butadiene at all nonequivalent bonds in free C(60), Ng@C(60), and Ng(2)@C(60) (Ng=He, Ne, Ar, Kr, and Xe). Our BP86/TZP calculations reveal that introduction of single noble gas atoms in Ng@C(60) and noble gas dimers He(2) and Ne(2) in Ng(2)@C(60) has almost no effect on the exohedral reactivity compared to free C(60), in agreement with experimental results. In all these cases cycloaddition is clearly favored at the [6,6] bonds in the fullerene cage. For the endohedral compounds He(2)@C(60) and Ne(2)@C(60) a slight preference (by less than 2 kcal mol(-1)) for bonds closer to the C(5) symmetry axis is found. This picture changes dramatically for the endohedral compounds with heavier noble gas dimers. Encapsulation of these noble gas dimers clearly enhances the reaction, both under thermodynamic and kinetic control. Moreover, in the case of Xe(2)@C(60), addition to [6,6] and [5,6] bonds becomes equally viable. These reactivity changes in endohedral fullerenes are attributed to stabilization of the LUMO, increased fullerene strain energy, and greater compression of the encapsulated Ng(2) unit along the He to Xe series.

  4. Noble gas tracers of ventilation during deep-water formation in the Weddell Sea

    NASA Astrophysics Data System (ADS)

    Nicholson, D. P.; Khatiwala, S.; Heimbach, P.

    2016-05-01

    To explore the dynamics and implications of incomplete air-sea equilibration during the formation of abyssal water masses, we simulated noble gases in the Estimating the Circulation & Climate of the Ocean (ECCO) global ocean state estimate. A novel computation approach utilizing a matrix-free Newton-Krylov (MFNK) scheme was applied to quickly compute the periodic seasonal solutions for noble gas tracers. MFNK allows for quick computation of a cyclo-stationary solution for tracers (i.e., a spun-up, repeating seasonal cycle), which would otherwise be computationally infeasible due to the long time scale of dynamic adjustment of the abyssal ocean (1000’s of years). A suite of experiments isolates individual processes, including atmospheric pressure effects, the solubility pump and air-sea bubble fluxes. In addition to these modeled processes, a volumetric contribution of 0.28 ± 0.07% of glacial melt water is required to reconcile deep-water observations in the Weddell Sea. Another primary finding of our work is that the saturation anomaly of heavy noble gases in model simulations is in excess of two-fold more negative than is suggested from Weddell Sea observations. This result suggests that model water masses are insufficiently ventilated prior to subduction and thus there is insufficient communication between atmosphere and ocean at high latitudes. The discrepancy between noble gas observations and ECCO simulations highlights that important inadequacies remain in how we model high-latitude ventilation with large implications for the oceanic uptake and storage of carbon.

  5. Reply to: “Recycled” volatiles in mantle derived diamonds—Evidence from nitrogen and noble gas isotopic data

    NASA Astrophysics Data System (ADS)

    Gautheron, Cécile; Cartigny, Pierre; Moreira, Manuel; Harris, Jeff W.; Allègre, Claude J.

    2006-11-01

    In a reinterpretation of our published rare gas data obtained on polycrystalline diamonds from the Orapa kimberlite (Botswana) [C.E. Gautheron, P. Cartigny, M. Moreira, J.W. Harris and C.J. Allègre, Evidence for a mantle component shown by rare gases, C. and N isotopes in polycrystalline diamonds from Orapa (Botswana), Earth Planet. Sci. Lett., 240 (2005) 559-572.], Mohapatra and Honda [R.K. Mohapatra, and M. Honda, "Recycled" volatiles in mantle derived diamonds-evidence from nitrogen and noble gas isotopic data, Earth Planet. Sci. Lett., this issue, 2006.] claim that mixing between a-priori defined proportions of subducted seawater, subducted recycled oceanic crust, recycled sediments, air and the mantle would be more appropriate to account for the observations. This view sharply contrasts with our conclusions that the chemical and isotope compositions of rare gases record diamond formation from mantle-derived fluid(s) together with mantle post-crystallization radiogenic/nucleogenic/fissiogenic ingrowth and preferential diffusion of the lightest atoms out of the diamonds in the mantle [C.E. Gautheron, P. Cartigny, M. Moreira, J.W. Harris and C.J. Allègre, Evidence for a mantle component shown by rare gases, C and N isotopes in polycrystalline diamonds from Orapa (Botswana), Earth Planet. Sci. Lett., 240 (2005) 559-572.]. We present here reasons why the alternative view of Mohapatra and Honda [R.K. Mohapatra and M. Honda, "Recycled" volatiles in mantle derived diamonds-evidence from nitrogen and noble gas isotopic data, Earth Planet. Sci. Lett., this issue, 2006.] is not supportable.

  6. 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.

  7. Structure and stability of noble gas bound EX3+ compounds (E = C, Ge, Sn, Pb; X = H, F, Cl, Br).

    PubMed

    Pan, Sudip; Moreno, Diego; Ghosh, Sreyan; Chattaraj, Pratim K; Merino, Gabriel

    2016-01-15

    It has been analyzed at the MP2/def2-QZVPPD level whether EX3+ (E = C-Pb; X = H, F-Br) can bind noble gas atoms. Geometrical and electronic structures, dissociation energy values, thermochemical parameters, natural bond order, electron density, and energy decomposition analyses highlight the possibility of such noble gas bound EX3+ compounds. Except He and Ne, the other heavier congeners of this family make quite strong bonds with E. In fact, the dissociations of Ar-Rn bound analogues turn out to be endergonic in nature at 298 K, except in the cases of ArGe Cl3+, Ar/KrGeBr3+, and ArSnBr3+. GeH3+ and EF3+ (E = Ge-Pb) can even bind two Ng atoms with reasonably high dissociation energy. As the pz orbital of the E center in EX3+ plays a crucial role in its binding with the noble gas atoms, the effect of the π back-bonding causing X → E electron transfer ought to be properly understood. Due to the larger back-donation, the Ng binding ability of EX3+ gradually decreases along F to Br. EH2+ and the global minimum HE(+…) H2 (E = Sn, Pb) complexes are also able to bind Ar-Rn atoms quite effectively. The NgE bonds in Ar-Rn bound CH3+, GeH3+, and EF3+ (E = Ge-Pb) and Xe/RnE bonds in NgECl3+ and NgEBr3+ (E = Ge, Sn) are mainly of covalent type.

  8. Shock Compression of Cryogenic Noble Gas Mixtures: Xenon - Krypton

    NASA Astrophysics Data System (ADS)

    Root, Seth; Magyar, Rudolph; Lemke, Raymond; Mattsson, Thomas

    2013-06-01

    In past work, we have examined the multi-Mbar response of cryogenically cooled liquid xenon and liquid krypton measuring their Hugoniots to 8 Mbar. These results were utilized in the development of new EOS models for Xe and Kr to use in high energy density physics applications. The previous work demonstrated the usefulness of integrating high accuracy shock compression experiments with DFT to generate the basis for equation of state (EOS) models. In many physics applications, such as Z-pinch experiments, gas mixtures are used instead. However, we do not have reliable experimental data on these mixtures to provide informed decisions about the EOS models or mixture rules. To improve our understanding of mixtures at extreme conditions, we performed dynamic compression experiments using Sandia's Z - facility on a 70/30 molar ratio Kr/Xe cryogenically cooled liquid mixture. We measured the Hugoniot state and reshock state of the liquid mixture to several Mbar. The experimental data validated the DFT simulations for identical molar ratio mixtures. The combined experimental and DFT results are used to assess the EOS models and test the mixture rules. 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.

  9. Spin Polarization Spectroscopy of Alkali-Noble Gas Interatomic Potentials

    NASA Astrophysics Data System (ADS)

    Mironov, Andrey E.; Goldshlag, William; Eden, J. Gary

    2017-06-01

    We report a new laser spectroscopic technique capable of detecting weak state-state interactions in diatomic molecules. Specifically, a weak interaction has been observed between the 6pσ antibonding orbital of the CsXe (B ^2Σ^+_{1/2}) state and a 5dσ MO associated with a 5dΛ (Λ = 0, 1) state. Thermal Cs-rare gas collision pairs are photoexcited by a circularly-polarized optical field having a wavelength within the B ^2Σ^+_{1/2} \\longleftarrow X ^2Σ^+_{1/2} (free\\longleftarrowfree) continuum. Subsequent dissociation of the B ^2Σ^+_{1/2} transient diatomic selectively populates the F= 4, 5 hyperfine levels of the Cs 6p ^2P_{3/2} state, and circularly-polarized (σ^+) amplified spontaneous emission (ASE) is generated on the Cs D_2 line. The dependence of Cs 6p spin polarization on the Cs(6p)-Xe internuclear separation (R), clearly shows an interaction between the CsXe(B ^2Σ^+_{1/2}) state and a 5dΛ (Λ = 0, 1) potential of the diatomic molecule.

  10. 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

  11. 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.

  12. Anatomy of a cluster IDP. Part 2: Noble gas abundances, trace element geochemistry, isotopic abundances, and trace organic chemistry of several fragments from L2008#5

    NASA Technical Reports Server (NTRS)

    Thomas, K. L.; Clemett, S. J.; Flynn, G. J.; Keller, L. P.; Mckay, David S.; Messenger, S.; Nier, A. O.; Schlutter, D. J.; Sutton, S. R.; Walker, R. M.

    1994-01-01

    The topics discussed include the following: noble gas content and release temperatures; trace element abundances; heating summary of cluster fragments; isotopic measurements; and trace organic chemistry.

  13. Neutralization of solvated protons and formation of noble-gas hydride molecules: Matrix-isolation indications of tunneling mechanisms?

    SciTech Connect

    Khriachtchev, Leonid; Lignell, Antti; Raesaenen, Markku

    2005-08-08

    The (NgHNg){sup +} cations (Ng=Ar and Kr) produced via the photolysis of HF/Ar, HF/Kr, and HBr/Kr solid mixtures are studied, with emphasis on their decay mechanisms. The present experiments provide a large variety of parameters connected to this decay phenomenon, which allows us to reconsider various models for the decay of the (NgHNg){sup +} cations in noble-gas matrices. As a result, we propose that this phenomenon could be explained by the neutralization of the solvated protons by electrons. The mechanism of this neutralization reaction probably involves tunneling of an electron from an electronegative fragment or another trap to the (NgHNg){sup +} cation. The proposed electron-tunneling mechanism should be considered as a possible alternative to the literature models based on tunneling-assisted or radiation-induced diffusion of protons in noble-gas solids. As a novel experimental observation of this work, the efficient formation of HArF molecules occurs at 8 K in a photolyzed HF/Ar matrix. It is probable that the low-temperature formation of HArF involves local tunneling of the H atom to the Ar-F center, which in turn supports the locality of HF photolysis in solid Ar. In this model, the decay of (ArHAr){sup +} ions and the formation of HArF molecules observed at low temperatures are generally unconnected processes; however, the decaying (ArHAr){sup +} ions may contribute to some extent to the formation of HArF molecules.

  14. 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.

  15. 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.

  16. Looking for a correlation between terrestrial age and noble gas record of H chondrites

    NASA Astrophysics Data System (ADS)

    Loeken, Th.; Schultz, L.

    1994-07-01

    On the basis of statistically significant concentration differences of some trace elements, it has been suggested that H chondrites found in Antarctica and Modern Falls represent members of different extraterrestrial populations with different thermal histories. It was also concluded that H chondrites found in Victoria Land (Allan Hills) differ chemically from those found in Queen Maud Land (Yamato Mountains), an effect that could be based on the different terrestrial age distribution of both groups. This would imply a change of the meteoroid flux hitting the Earth on a timescale that is comparable to typical terrestrial ages of Antarctic chondrites. A comparison of the noble gas record of H chondrites from the Allan Hills icefields and Modern Fall shows that the distributions of cosmic-ray exposure ages and the concentrations of radiogenic He-4 and Ar-40 are very similar. In an earlier paper we compared the noble gas measurements of 20 Yamato H contents with meteorites from the Allan Hills region and Modern Falls. Similar distributions were found. The distribution of cosmic-ray exposure ages and radiogenic He-4 and Ar-40 gas contents as a function of the terrestrial age is investigated in these chondrites. The distribution shows the well-known 7-Ma-cluster indicating that about 40% of the H chondrites were excavated from their parent body in a single event. Both populations, Antarctic Meteorites and Modern Falls, exhibit the same characteristic feature: a major meteoroid-producing event about 7 Ma. This indicates that one H-group population delivers H chondrites to Antarctica and the rest of the world. Cosmic-ray exposure ages and thermal-history indicaters like radiogenic noble gases show no evidence of a change in the H chondrite meteoroid population during the last 200,000 years.

  17. Petrographic shock indicators and noble gas signatures in a H and an L chondrite from Antarctica

    NASA Astrophysics Data System (ADS)

    Ranjith, P. M.; He, Huaiyu; Miao, Bingkui; Su, Fei; Zhang, Chuantong; Xia, Zhipeng; Xie, Lanfang; Zhu, Rixiang

    2017-10-01

    Petrographic shock indicators and noble gas signatures are studied in two ordinary chondrites, Grove Mountain (GRV) 13083 (H4) and GRV 13095 (L5), from Antarctica to investigate the degree of shock metamorphism and impact related chronologies on H and L chondrite parent bodies. In the study, we have combined both noble gas signatures and petrographic observations to understand impact effects. Based on the impact features in silicates and metal-troilite assemblages, the shock stages of the samples are classified as S6 and S5 for GRV 13095 (L5) and GRV 13083 (H4) respectively. The nominal K-Ar gas retention age of GRV 13095 (L5, S6) using bulk sample is estimated as 459 ± 13 Ma, supporting the recent major catastrophic break up event at 470 Ma on the L-chondrite parent body. The cosmic ray exposure age based on He, Ne and Ar noble gas measurements is estimated as 14.1 ± 2.5 Ma. The radiogenic gas contents in GRV 13095 (avg. 4He = 61.5 × 10-8 ccSTP/g and avg. 40Ar = 173.5 × 10-8 ccSTP/g) are observed as depleted. The depletion in radiogenic gases is consistent with the severe shock metamorphism in GRV 13095 as indicated by olivine-ringwoodite transformation in it. The estimated nominal K-Ar age of 3.67 ± 0.26 Ga for GRV 13083 shows that it falls in the major impact age distribution between 3.5 and 4.0 Ga among H-chondrites. The cosmic ray exposure age of GRV 13083 is 3.9 ± 0.7 Ma, which is younger than the major peak in the exposure age distribution for H-chondrites. The He gas retention ages in both samples are found to be younger/lower than their respective nominal K-Ar ages, which could be due to partial loss of radiogenic He. Trapped gas loss along with radiogenic gas losses in both samples, are the adverse effects of shock metamorphism.

  18. Metal powder production by gas atomization

    NASA Technical Reports Server (NTRS)

    Ting, E. Y.; Grant, N. J.

    1986-01-01

    The confined liquid, gas-atomization process was investigated. Results from a two-dimensional water model showed the importance of atomization pressure, as well as delivery tube and atomizer design. The atomization process at the tip of the delivery tube was photographed. Results from the atomization of a modified 7075 aluminum alloy yielded up to 60 wt pct. powders that were finer than 45 microns in diameter. Two different atomizer designs were evaluated. The amount of fine powders produced was correlated to a calculated gas-power term. An optimal gas-power value existed for maximized fine powder production. Atomization at gas-power greater than or less than this optimal value produced coarser powders.

  19. High efficiency noble gas electron impact ion source for isotope separation

    SciTech Connect

    Appelhans, A. D.; Olson, J. E.; Dahl, D. A.; Ward, M. B.

    2016-07-01

    An electron impact ion source has been designed for generation of noble gas ions in a compact isotope separator. The source utilizes a circular filament that surrounds an ionization chamber, enabling multiple passes of electrons through the ionization chamber. This report presents ion optical design and the results of efficiency and sensitivity measurements performed in an ion source test chamber and in the compact isotope separator. The cylindrical design produced xenon ions at an efficiency of 0.37% with a sensitivity of ~24 µA /Pa at 300 µA of electron current.

  20. Sensitivity analysis of the noble gas transport and fate model: CASCADR9

    SciTech Connect

    Lindstrom, F.T.; Cawlfield, D.E.; Barker, L.E.

    1994-03-01

    CASCADR9 is a desert alluvial soil site-specific noble gas transport and fate model. Input parameters for CASCADR9 are: man-made source term, background concentration of radionuclides, radon half-life, soil porosity, period of barometric pressure wave, amplitude of barometric pressure wave, and effective eddy diffusivity. Using average flux, total flow, and radon concentration at the 40 day mark as output parameters, a sensitivity analysis for CASCADR9 is carried out, under a variety of scenarios. For each scenario, the parameter to which output parameters are most sensitive are identified.

  1. Steady state fractionation of heavy noble gas isotopes in a deep unsaturated zone

    USGS Publications Warehouse

    Seltzer, Alan M.; Severinghaus, Jeffrey P.; Andraski, Brian; Stonestrom, David A.

    2017-01-01

    To explore steady state fractionation processes in the unsaturated zone (UZ), we measured argon, krypton, and xenon isotope ratios throughout a ∼110 m deep UZ at the United States Geological Survey (USGS) Amargosa Desert Research Site (ADRS) in Nevada, USA. Prior work has suggested that gravitational settling should create a nearly linear increase in heavy-to-light isotope ratios toward the bottom of stagnant air columns in porous media. Our high-precision measurements revealed a binary mixture between (1) expected steady state isotopic compositions and (2) unfractionated atmospheric air. We hypothesize that the presence of an unsealed pipe connecting the surface to the water table allowed for direct inflow of surface air in response to extensive UZ gas sampling prior to our first (2015) measurements. Observed isotopic resettling in deep UZ samples collected a year later, after sealing the pipe, supports this interpretation. Data and modeling each suggest that the strong influence of gravitational settling and weaker influences of thermal diffusion and fluxes of CO2 and water vapor accurately describe steady state isotopic fractionation of argon, krypton, and xenon within the UZ. The data confirm that heavy noble gas isotopes are sensitive indicators of UZ depth. Based on this finding, we outline a potential inverse approach to quantify past water table depths from noble gas isotope measurements in paleogroundwater, after accounting for fractionation during dissolution of UZ air and bubbles.

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

    PubMed

    Anderson, D L

    1998-08-04

    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 ( approximately 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.

  3. Steady state fractionation of heavy noble gas isotopes in a deep unsaturated zone

    NASA Astrophysics Data System (ADS)

    Seltzer, Alan M.; Severinghaus, Jeffrey P.; Andraski, Brian J.; Stonestrom, David A.

    2017-04-01

    To explore steady state fractionation processes in the unsaturated zone (UZ), we measured argon, krypton, and xenon isotope ratios throughout a ˜110 m deep UZ at the United States Geological Survey (USGS) Amargosa Desert Research Site (ADRS) in Nevada, USA. Prior work has suggested that gravitational settling should create a nearly linear increase in heavy-to-light isotope ratios toward the bottom of stagnant air columns in porous media. Our high-precision measurements revealed a binary mixture between (1) expected steady state isotopic compositions and (2) unfractionated atmospheric air. We hypothesize that the presence of an unsealed pipe connecting the surface to the water table allowed for direct inflow of surface air in response to extensive UZ gas sampling prior to our first (2015) measurements. Observed isotopic resettling in deep UZ samples collected a year later, after sealing the pipe, supports this interpretation. Data and modeling each suggest that the strong influence of gravitational settling and weaker influences of thermal diffusion and fluxes of CO2 and water vapor accurately describe steady state isotopic fractionation of argon, krypton, and xenon within the UZ. The data confirm that heavy noble gas isotopes are sensitive indicators of UZ depth. Based on this finding, we outline a potential inverse approach to quantify past water table depths from noble gas isotope measurements in paleogroundwater, after accounting for fractionation during dissolution of UZ air and bubbles.

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

    PubMed Central

    Anderson, Don L.

    1998-01-01

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

  5. Mechanisms of disruptions caused by noble gas injection into tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Morozov, D. Kh.; Yurchenko, E. I.; Lukash, V. E.; Baronova, E. O.; Pozdnyakov, Yu. I.; Rozhansky, V. A.; Senichenkov, I. Yu.; Veselova, I. Yu.; Schneider, R.

    2005-08-01

    Noble gas injection for disruption mitigation in DIII-D is simulated. The simulation of the first two stages of the disruption is performed: the first one is the neutral gas jet penetration through the background plasmas, and the second one is the instability growth. In order to simulate the first stage, the MHD pellet code LLP with improved radiation model for noble gas is used. Plasma cooling at this stage is provided by the energy exchange with the jet. The opacity effects in radiation losses are found to be important in the energy balance calculations. The magnetic surfaces in contact with the jet are cooled significantly; however, the temperature as well as the electric conductivity, remains high. The cooling front propagates towards the plasma centre. It has been shown that the cooling front is accompanied by strongly localized 'shark fin-like' perturbation in toroidal current density profile. The simplified cylindrical model shows that the cooling front is able to produce the internal kink-like mode with growth rate significantly higher than the tearing mode. The unstable kink perturbation obtained is non-resonant for any magnetic surface, both inside the plasma column, and in the vacuum space outside the separatrix. The mode disturbs mainly the core region. The growth time of the 'shark fin-like' mode is higher than the Alfven time by a factor of 10-100 for DIII-D parameters.

  6. Disruption mitigation by injection of small quantities of noble gas in ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Pautasso, G.; Bernert, M.; Dibon, M.; Duval, B.; Dux, R.; Fable, E.; Fuchs, J. C.; Conway, G. D.; Giannone, L.; Gude, A.; Herrmann, A.; Hoelzl, M.; McCarthy, P. J.; Mlynek, A.; Maraschek, M.; Nardon, E.; Papp, G.; Potzel, S.; Rapson, C.; Sieglin, B.; Suttrop, W.; Treutterer, W.; The ASDEX Upgrade Team; The EUROfusion MST1 Team

    2017-01-01

    The most recent experiments of disruption mitigation by massive gas injection in ASDEX Upgrade have concentrated on small—relatively to the past—quantities of noble gas injected, and on the search for the minimum amount of gas necessary for the mitigation of the thermal loads on the divertor and for a significant reduction of the vertical force during the current quench. A scenario for the generation of a long-lived runaway electron beam has been established; this allows the study of runaway current dissipation by moderate quantities of argon injected. This paper presents these recent results and discusses them in the more general context of physical models and extrapolation, and of the open questions, relevant for the realization of the ITER disruption mitigation system.

  7. Effect of the medium on intramolecular H-atom tunneling: cis-trans conversion of formic acid in solid matrixes of noble gases.

    PubMed

    Trakhtenberg, Leonid I; Fokeyev, Anatoly A; Zyubin, Alexander S; Mebel, Alexander M; Lin, S H

    2010-12-30

    Intramolecular tunneling of a hydrogen atom in formic acid at low temperatures has been studied theoretically on the basis of quantum-chemical modeling of HCOOH@Nb(12) clusters. Three noble matrixes (Ar, Kr, and Xe) are considered. Energetic and geometric parameters as well as vibrational frequencies for the formic acid in cis and trans configurations surrounded by 12 Nb atoms are calculated within the frame of the MP2 approach with extended basis sets. The rate constant of HCOOH cis-trans conversion is analyzed by taking into account matrix reorganization and the change of HCOOH position in the cluster. The matrix reorganization is considered within the Debye model of lattice vibrations, whereas the external motion of HCOOH in the cluster is treated using the Einstein model of solids. It has been shown that the literature experimental data on the cis to trans tunneling reaction in the formic acid can be accounted for within the proposed mechanism, which describes the matrix reorganization and the change of the HCOOH position in the noble gas matrix, with fitting parameters of the suggested theoretical model attaining reasonable values.

  8. 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.

  9. van der Waals radii of noble gases.

    PubMed

    Vogt, Jürgen; Alvarez, Santiago

    2014-09-02

    Consistent van der Waals radii are deduced for Ne-Xe, based on the noble gas···oxygen intermolecular distances found in gas phase structures. The set of radii proposed is shown to provide van der Waals distances for a wide variety of noble gas···element atom pairs that represent properly the distribution of distances both in the gas phase and in the solid state. Moreover, these radii show a smooth periodic trend down the group which is parallel to that shown by the halogens.

  10. Non-solar noble gas abundances in the atmosphere of Jupiter

    NASA Technical Reports Server (NTRS)

    Lunine, Jonathan I.; Stevenson, David J.

    1986-01-01

    The thermodynamic stability of clathrate hydrate is calculated to predict the formation conditions corresponding to a range of solar system parameters. The calculations were performed using the statistical mechanical theory developed by van der Waals and Platteeuw (1959) and existing experimental data concerning clathrate hydrate and its components. Dissociation pressures and partition functions (Langmuir constants) are predicted at low pressure for CO clathrate (hydrate) using the properties of chemicals similar to CO. It is argued that nonsolar but well constrained noble gas abundances may be measurable by the Galileo spacecraft in the Jovian atmosphere if the observed carbon enhancement is due to bombardment of the atmosphere by clathrate-bearing planetesimals sometime after planetary formation. The noble gas abundances of the Jovian satellite Titan are predicted, assuming that most of the methane in Titan is accreted as clathrate. It is suggested that under thermodynamically appropriate conditions, complete clathration of water ice could have occurred in high-pressure nebulas around giant planets, but probably not in the outer solar nebula. The stability of clathrate in other pressure ranges is also discussed.

  11. Noble gas patterns in the atmospheres of Mars and Earth: A comparison via the SNC meteorites

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    Noble gas and nitrogen compositions in the glassy phase of the EETA 79001 shergottite correspond closely with Viking measurements. This direct evidence for the origin of the SNC meteorites on Mars, and for trapping of an unfractionated sample of Martian atmospheric gases in the 79001 glass, provides a reasonable basis for comparing the Martian and terrestrial atmospheres with more precision than that afforded by the Viking data set. Results are that, with one exception, elemental and isotopic compositions of nonradiogenic Martian noble gases are similar to those in the Earth's atmosphere; relatively small isotopic discrepancies in Kr and perhaps Xe may be attributable to different degrees of mass fractionation of a common parent reservoir. The anomaly is in Ar composition, where Martian Ar-36/AR-38 approx. 4 is strikingly lower than the values near 5.3 that characterize both the Earth and major meteoritic gas carriers. Although a primordial Martian ratio of 5.3 could in principle be altered by some planet specific process (e.g., cosmic ray spallation of surface materials) operating over geologic time, one has not been found that works.

  12. Noble gas composition of subcontinental lithospheric mantle: An extensively degassed reservoir beneath Southern Patagonia

    NASA Astrophysics Data System (ADS)

    Jalowitzki, Tiago; Sumino, Hirochika; Conceição, Rommulo V.; Orihashi, Yuji; Nagao, Keisuke; Bertotto, Gustavo W.; Balbinot, Eduardo; Schilling, Manuel E.; Gervasoni, Fernanda

    2016-09-01

    Patagonia, in the Southern Andes, is one of the few locations where interactions between the oceanic and continental lithosphere can be studied due to subduction of an active spreading ridge beneath the continent. In order to characterize the noble gas composition of Patagonian subcontinental lithospheric mantle (SCLM), we present the first noble gas data alongside new lithophile (Sr-Nd-Pb) isotopic data for mantle xenoliths from Pali-Aike Volcanic Field and Gobernador Gregores, Southern Patagonia. Based on noble gas isotopic compositions, Pali-Aike mantle xenoliths represent intrinsic SCLM with higher (U + Th + K)/(3He, 22Ne, 36Ar) ratios than the mid-ocean ridge basalt (MORB) source. This reservoir shows slightly radiogenic helium (3He/4He = 6.84-6.90 RA), coupled with a strongly nucleogenic neon signature (mantle source 21Ne/22Ne = 0.085-0.094). The 40Ar/36Ar ratios vary from a near-atmospheric ratio of 510 up to 17700, with mantle source 40Ar/36Ar between 31100-6800+9400 and 54000-9600+14200. In addition, the 3He/22Ne ratios for the local SCLM endmember, at 12.03 ± 0.15 to 13.66 ± 0.37, are higher than depleted MORBs, at 3He/22Ne = 8.31-9.75. Although asthenospheric mantle upwelling through the Patagonian slab window would result in a MORB-like metasomatism after collision of the South Chile Ridge with the Chile trench ca. 14 Ma, this mantle reservoir could have remained unhomogenized after rapid passage and northward migration of the Chile Triple Junction. The mantle endmember xenon isotopic ratios of Pali-Aike mantle xenoliths, which is first defined for any SCLM-derived samples, show values indistinguishable from the MORB source (129Xe/132Xe =1.0833-0.0053+0.0216 and 136Xe/132Xe =0.3761-0.0034+0.0246). The noble gas component observed in Gobernador Gregores mantle xenoliths is characterized by isotopic compositions in the MORB range in terms of helium (3He/4He = 7.17-7.37 RA), but with slightly nucleogenic neon (mantle source 21Ne/22Ne = 0.065-0.079). We

  13. Evaluating Gas-Phase Transport And Detection Of Noble Gas Signals From Underground Nuclear Explosions Using Chemical Tracers

    NASA Astrophysics Data System (ADS)

    Carrigan, C. R.; Hunter, S. L.; Sun, Y.; Wagoner, J. L.; Ruddle, D.; Anderson, G.; Felske, D.; Myers, K.; Zucca, J. J.; Emer, D. F.; Townsend, M.; Drellack, S.; Chipman, V.; Snelson, C. M.

    2013-12-01

    The 1993 Non-Proliferation Experiment (NPE) involved detonating 1 kiloton of chemical explosive in a subsurface cavity which also contained bottles of tracer gases (ref 1). That experiment provided an improved understanding of transport processes relevant to the detection of noble gas signals at the surface emanating from a clandestine underground nuclear explosion (UNE). As an alternative to performing large chemical detonations to simulate gas transport from UNEs, we have developed a test bed for subsurface gas transport, sampling and detection studies using a former UNE cavity. The test bed site allows for the opportunity to evaluate pathways to the surface created by the UNE as well as possible transport mechanisms including barometric pumping and cavity pressurization (ref 2). With the test bed we have monitored long-term chemical tracers as well as newly injected tracers. In order to perform high temporal resolution tracer gas monitoring, we have also developed a Subsurface Gas Smart Sampler (SGSS) which has application during an actual On Site Inspection (OSI) and is available for deployment in OSI field exercises planned for 2014. Deployment of five SGSS at the remote test bed has provided unparalleled detail concerning relationships involving tracer gas transport to the surface, barometric fluctuations and temporal variations in the natural radon concentration. We anticipate that the results of our tracer experiments will continue to support the development of improved noble gas detection technology for both OSI and International Monitoring System applications. 1. C.R. Carrigan et al., 1996, Nature, 382, p. 528. 2. Y. Sun and C.R. Carrigan, 2012, Pure Appl. Geophys., DOI 10.1007/s00024-012-0514-4.

  14. Noble gas binding to human serum albumin using docking simulation: nonimmobilizers and anesthetics bind to different sites.

    PubMed

    Seto, Tomoyoshi; Isogai, Hideto; Ozaki, Masayuki; Nosaka, Shuichi

    2008-10-01

    Nonimmobilizers are structurally similar to anesthetics, but do not produce anesthesia at clinically relevant concentrations. Xenon, krypton, and argon are anesthetics, whereas neon and helium are nonimmobilizers. The structures of noble gases with anesthetics or nonimmobilizers are similar and their interactions are simple. Whether the binding site of anesthetics differs from that of nonimmobilizers has long been a question in molecular anesthesiology. We investigated the binding sites and energies of anesthetic and nonimmobilizer noble gases in human serum albumin (HSA) because the 3D structure of HSA is well known and it has an anesthetic binding site. The computational docking simulation we used searches for binding sites and calculates the binding energy for small molecules and a template molecule. Xenon, krypton, and argon were found to bind to the enflurane binding site of HSA, whereas neon and helium were found to bind to sites different from the xenon binding site. Rare gas anesthetic binding was dominated by van der Waals energy, while nonimmobilizer binding was dominated by solvent-effect energy. Binding site preference was determined by the ratios of local binding energy (van der Waals energy) and nonspecific binding energy (solvent-effect energy) to the total binding energy. van der Waals energy dominance is necessary for anesthetic binding. This analysis of binding energy components provides a rationale for the binding site difference of anesthetics and nonimmobilizers, reveals the differences between the binding interactions of anesthetics and nonimmobilizers, may explain pharmacological differences between anesthetics and nonimmobilizers, and provide an understanding of anesthetic action at the atomic level.

  15. 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.; hide

    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).

  16. Testing of a prototype of calibration facility for noble gas monitoring using 41Ar.

    PubMed

    Saibathulham, Holnisar; Wurdiyanto, Gatot; Marsum, Pujadi

    2012-09-01

    A prototype of a calibration facility for noble gas monitoring using (41)Ar in the PTKMR-BATAN has been tested. The facility was designed in such a way that the standard source of gas can be reused. The radioactive (41)Ar source was obtained by thermal neutron reaction of (40)Ar(n, γ)(41)Ar using a thermal neutron flux of 4.8×10(13) neutrons per cm(2) per second in two minutes on the multipurpose G.A. Siwabessy Reactor (Batan, Serpong, Indonesia). Gamma spectrometry was used to measure the radioactivity and purity of (41)Ar. The spectrum of the (41)Ar observed yields an energy of 1294 keV because of the highest intensity (99.2%). The activity of (41)Ar was 2821 kBq and 4% of the expanded uncertainty. The time required for (41)Ar to reach homogeneity was 7 min, and the effectiveness of resuse was 53%.

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

    SciTech Connect

    Baldwin, D L

    1981-01-01

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

  18. Demonstration of neutron detection utilizing open cell foam and noble gas scintillation

    SciTech Connect

    Lavelle, C. M. Miller, E. C.; Coplan, M.; Thompson, Alan K.; Vest, Robert E.; Yue, A. T.; Kowler, A. L.; Koeth, T.; Al-Sheikhly, M.; Clark, Charles W.

    2015-03-02

    We present results demonstrating neutron detection via a closely spaced converter structure coupled to low pressure noble gas scintillation instrumented by a single photo-multiplier tube (PMT). The converter is dispersed throughout the gas volume using a reticulated vitreous carbon foam coated with boron carbide (B{sub 4}C). A calibrated cold neutron beam is used to measure the neutron detection properties, using a thin film of enriched {sup 10}B as a reference standard. Monte Carlo computations of the ion energy deposition are discussed, including treatment of the foam random network. Results from this study indicate that the foam shadows a significant portion of the scintillation light from the PMT. The high scintillation yield of Xe appears to overcome the light loss, facilitating neutron detection and presenting interesting opportunities for neutron detector design.

  19. A system for low field imaging of laser-polarized noble gas

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    We describe a device for performing MRI with laser-polarized noble gas at low magnetic fields (<50 G). The system is robust, portable, inexpensive, and provides gas-phase imaging resolution comparable to that of high field clinical instruments. At 20.6 G, we have imaged laser-polarized (3)He (Larmor frequency of 67 kHz) in both sealed glass cells and excised rat lungs, using approximately 0.1 G/cm gradients to achieve approximately 1 mm(2) resolution. In addition, we measured (3)He T(2)(*) times greater than 100 ms in excised rat lungs, which is roughly 20 times longer than typical values observed at high ( approximately 2 T) fields. We include a discussion of the practical considerations for working at low magnetic fields and conclude with evidence of radiation damping in this system. Copyright 1999 Academic Press.

  20. 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).

  1. Pressure disequilibria induced by rapid valve closure in noble gas extraction lines

    USGS Publications Warehouse

    Morgan, Leah; Davidheiser-Kroll, Brett

    2015-01-01

    Pressure disequilibria during rapid valve closures can affect calculated molar quantities for a range of gas abundance measurements (e.g., K-Ar geochronology, (U-Th)/He geochronology, noble gas cosmogenic chronology). Modeling indicates this effect in a system with a 10 L reservoir reaches a bias of 1% before 1000 pipette aliquants have been removed from the system, and a bias of 10% before 10,000 aliquants. Herein we explore the causes and effects of this problem, which is the result of volume changes during valve closure. We also present a solution in the form of an electropneumatic pressure regulator that can precisely control valve motion. This solution reduces the effect to ∼0.3% even after 10,000 aliquants have been removed from a 10 L reservoir.

  2. A system for low field imaging of laser-polarized noble gas

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    We describe a device for performing MRI with laser-polarized noble gas at low magnetic fields (<50 G). The system is robust, portable, inexpensive, and provides gas-phase imaging resolution comparable to that of high field clinical instruments. At 20.6 G, we have imaged laser-polarized (3)He (Larmor frequency of 67 kHz) in both sealed glass cells and excised rat lungs, using approximately 0.1 G/cm gradients to achieve approximately 1 mm(2) resolution. In addition, we measured (3)He T(2)(*) times greater than 100 ms in excised rat lungs, which is roughly 20 times longer than typical values observed at high ( approximately 2 T) fields. We include a discussion of the practical considerations for working at low magnetic fields and conclude with evidence of radiation damping in this system. Copyright 1999 Academic Press.

  3. “Recycled” volatiles in mantle-derived diamonds— Evidence from nitrogen and noble gas isotopic data

    NASA Astrophysics Data System (ADS)

    Mohapatra, Ratan K.; Honda, Masahiko

    2006-11-01

    Noble gas isotopic data from diamonds are commonly interpreted as a two component mixture of gases from the mantle source of mid oceanic ridge basalt (MORB) and air. The air-like component in diamonds is generally considered to have been acquired secondarily through atmospheric contamination. In a recent study [C. Gautheron, P. Cartigny, M. Moreira, J.W. Harris, C.J. Allègre, Evidence for a mantle component shown by rare gases, C and N isotopes in polycrystalline diamonds from Orapa (Botswana), Earth Planet. Sci. Lett. 240(2005) 559-572.] that involved analyses of noble gases, carbon and nitrogen, such interpretation based on noble gases is used to constrain the sources of carbon and nitrogen in diamond to be solely from the mantle. With the help of heavy noble gas and nitrogen isotopic data from diamonds, we show here that the air-like noble gas component in diamonds is actually a mixture of contributions derived from recycled materials and (minor) air contamination. This, in turn, suggests that some of the carbon in diamonds may also have a recycled origin.

  4. Electronic, Mechanical, and Dielectric Properties of Two-Dimensional Atomic Layers of Noble Metals

    NASA Astrophysics Data System (ADS)

    Kapoor, Pooja; Kumar, Jagdish; Kumar, Arun; Kumar, Ashok; Ahluwalia, P. K.

    2017-01-01

    We present density functional theory-based electronic, mechanical, and dielectric properties of monolayers and bilayers of noble metals (Au, Ag, Cu, and Pt) taken with graphene-like hexagonal structure. The Au, Ag, and Pt bilayers stabilize in AA-stacked configuration, while the Cu bilayer favors the AB stacking pattern. The quantum ballistic conductance of the noble-metal mono- and bilayers is remarkably increased compared with their bulk counterparts. Among the studied systems, the tensile strength is found to be highest for the Pt monolayer and bilayer. The noble metals in mono- and bilayer form show distinctly different electron energy loss spectra and reflectance spectra due to the quantum confinement effect on going from bulk to the monolayer limit. Such tunability of the electronic and dielectric properties of noble metals by reducing the degrees of freedom of electrons offers promise for their use in nanoelectronics and optoelectronics applications.

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

    NASA Astrophysics Data System (ADS)

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

    1994-07-01

    Since the first analyses of C and N isotopes in presolar diamonds with known noble gas isotope composition more than a decade ago [1,2] the investigation of these isotope systems in the diamonds were developed practicallly independently. During this time many interesting details in isotopic systematics of all the elements involved were found and reviewed [3-5]. The main conclusion now reached from a decade of investigation is that presolar diamonds from different meteorites are not identical but appear to consist of several populations [6-8]. Therefore a variety of circumstellar conditions may be involved through a type II supernova model is a good start point in trying to understand diamond synthesis [9]. The evidences from experimental data for all the isotope systems however are still not entirely consistent in the sense that we actually do not know how many carriers the diamonds represent and how the various noble gas carriers are related to those for nitrogen. The finding of a consensus between noble gas and light element analyses would seem to be a vital step so that more detailed nucleosynthesis models may be developed tor the diamond formation. A first point is to answer the question whether HL noble gases and light nitrogen must have been formed at the same astrophysical site. Another important achievement in terms of presolar diamond investigations during the last decade is the purity and number of samples now available. However a well known difficulty is that C, N, and noble gases are never measured all together on the same sample. The purpose of collaboration initiated in this paper is to exploit the availability of good quality samples and to go some way towards overcoming the difficulties of measurement technique incompatibility. We have analyzed three pure diamond samples separated at CalTech from Allende, Orgueil, (henceforth CT samples) and Leoville for N and C isotopic composition by stepped pyrolysis and combustion. The samples preparation and

  6. Molecular dynamics simulation of framework flexibility effects on noble gas diffusion in HKUST-1 and ZIF-8

    SciTech Connect

    Parkes, Marie V.; Demir, Hakan; Teich-McGoldrick, Stephanie L.; Sholl, David S.; Greathouse, Jeffery A.; Allendorf, Mark D.

    2014-03-28

    Molecular dynamics simulations were used to investigate trends in noble gas (Ar, Kr, Xe) diffusion in the metal-organic frameworks HKUST-1 and ZIF-8. Diffusion occurs primarily through inter-cage jump events, with much greater diffusion of guest atoms in HKUST-1 compared to ZIF-8 due to the larger cage and window sizes in the former. We compare diffusion coefficients calculated for both rigid and flexible frameworks. For rigid framework simulations, in which the framework atoms were held at their crystallographic or geometry optimized coordinates, sometimes dramatic differences in guest diffusion were seen depending on the initial framework structure or the choice of framework force field parameters. When framework flexibility effects were included, argon and krypton diffusion increased significantly compared to rigid-framework simulations using general force field parameters. Additionally, for argon and krypton in ZIF-8, guest diffusion increased with loading, demonstrating that guest-guest interactions between cages enhance inter-cage diffusion. No inter-cage jump events were seen for xenon atoms in ZIF-8 regardless of force field or initial structure, and the loading dependence of xenon diffusion in HKUST-1 is different for rigid and flexible frameworks. Diffusion of krypton and xenon in HKUST-1 depends on two competing effects: the steric effect that decreases diffusion as loading increases, and the “small cage effect” that increases diffusion as loading increases. Finally, a detailed analysis of the window size in ZIF-8 reveals that the window increases beyond its normal size to permit passage of a (nominally) larger krypton atom.

  7. Molecular dynamics simulation of framework flexibility effects on noble gas diffusion in HKUST-1 and ZIF-8

    DOE PAGES

    Parkes, Marie V.; Demir, Hakan; Teich-McGoldrick, Stephanie L.; ...

    2014-03-28

    Molecular dynamics simulations were used to investigate trends in noble gas (Ar, Kr, Xe) diffusion in the metal-organic frameworks HKUST-1 and ZIF-8. Diffusion occurs primarily through inter-cage jump events, with much greater diffusion of guest atoms in HKUST-1 compared to ZIF-8 due to the larger cage and window sizes in the former. We compare diffusion coefficients calculated for both rigid and flexible frameworks. For rigid framework simulations, in which the framework atoms were held at their crystallographic or geometry optimized coordinates, sometimes dramatic differences in guest diffusion were seen depending on the initial framework structure or the choice of frameworkmore » force field parameters. When framework flexibility effects were included, argon and krypton diffusion increased significantly compared to rigid-framework simulations using general force field parameters. Additionally, for argon and krypton in ZIF-8, guest diffusion increased with loading, demonstrating that guest-guest interactions between cages enhance inter-cage diffusion. No inter-cage jump events were seen for xenon atoms in ZIF-8 regardless of force field or initial structure, and the loading dependence of xenon diffusion in HKUST-1 is different for rigid and flexible frameworks. Diffusion of krypton and xenon in HKUST-1 depends on two competing effects: the steric effect that decreases diffusion as loading increases, and the “small cage effect” that increases diffusion as loading increases. Finally, a detailed analysis of the window size in ZIF-8 reveals that the window increases beyond its normal size to permit passage of a (nominally) larger krypton atom.« less

  8. Prediction of neutral noble gas insertion compounds with heavier pnictides: FNgY (Ng = Kr and Xe; Y = As, Sb and Bi).

    PubMed

    Ghosh, Ayan; Manna, Debashree; Ghanty, Tapan K

    2016-04-28

    A novel class of interesting insertion compounds obtained through the insertion of a noble gas atom into the heavier pnictides have been explored by various ab initio quantum chemical techniques. Recently, the first neutral noble gas insertion compounds, FXeY (Y = P, N), were theoretically predicted to be stable; the triplet state was found to be the most stable state, with a high triplet-singlet energy gap, by our group. In this study, we investigated another noble gas inserted compound, FNgY (Ng = Kr and Xe; Y = As, Sb and Bi), with a triplet ground state. Density functional theory (DFT), second order Møller-Plesset perturbation theory (MP2), coupled-cluster theory (CCSD(T)) and multi-reference configuration interaction (MRCI) based techniques have been utilized to investigate the structures, stabilities, harmonic vibrational frequencies, charge distributions and topological properties of these compounds. These predicted species, FNgY (Ng = Kr and Xe; Y = As, Sb and Bi) are found to be energetically stable with respect to all the probable 2-body and 3-body dissociation pathways, except for the 2-body channel leading to the global minimum products (FY + Ng). Nevertheless, the finite barrier height corresponding to the saddle points of the compounds connected to their respective global minima products indicates that these compounds are kinetically stable. The structural parameters, energetics, and charge distribution results as well as atoms-in-molecules (AIM) analysis suggest that these predicted molecules can be best represented as F(-)[(3)NgY](+). Thus, all the aforementioned computed results clearly indicate that it may be possible to experimentally prepare the most stable triplet state of FNgY molecules under cryogenic conditions through a matrix isolation technique.

  9. Methane Sources and Migration Mechanisms in Shallow Groundwaters in Parker and Hood Counties, Texas-A Heavy Noble Gas Analysis.

    PubMed

    Wen, Tao; Castro, M Clara; Nicot, Jean-Philippe; Hall, Chris M; Larson, Toti; Mickler, Patrick; Darvari, Roxana

    2016-11-01

    This study places constraints on the source and transport mechanisms of methane found in groundwater within the Barnett Shale footprint in Texas using dissolved noble gases, with particular emphasis on (84)Kr and (132)Xe. Dissolved methane concentrations are positively correlated with crustal (4)He, (21)Ne, and (40)Ar and suggest that noble gases and methane originate from common sedimentary strata, likely the Strawn Group. In contrast to most samples, four water wells with the highest dissolved methane concentrations unequivocally show strong depletion of all atmospheric noble gases ((20)Ne, (36)Ar, (84)Kr, (132)Xe) with respect to air-saturated water (ASW). This is consistent with predicted noble gas concentrations in a water phase in contact with a gas phase with initial ASW composition at 18 °C-25 °C and it suggests an in situ, highly localized gas source. All of these four water wells tap into the Strawn Group and it is likely that small gas accumulations known to be present in the shallow subsurface were reached. Additionally, lack of correlation of (84)Kr/(36)Ar and (132)Xe/(36)Ar fractionation levels along with (4)He/(20)Ne with distance to the nearest gas production wells does not support the notion that methane present in these groundwaters migrated from nearby production wells either conventional or using hydraulic fracturing techniques.

  10. 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

  11. The contribution of hydrothermally altered ocean crust to the mantle halogen and noble gas cycles

    NASA Astrophysics Data System (ADS)

    Chavrit, Déborah; Burgess, Ray; Sumino, Hirochika; Teagle, Damon A. H.; Droop, Giles; Shimizu, Aya; Ballentine, Chris J.

    2016-06-01

    Recent studies suggest that seawater-derived noble gases and halogens are recycled into the deep mantle by the subduction of oceanic crust. To understand the processes controlling the availability of halogens and noble gases for subduction, we determined the noble gas elemental and isotopic ratios and halogen (Cl, Br, I) concentrations in 28 igneous samples from the altered oceanic crust (AOC) from 5 ODP sites in the Eastern and Western Pacific Ocean. Crushing followed by heating experiments enabled determination of noble gases and halogens in fluid inclusions and mineral phases respectively. Except for He and Ar, Ne, Kr and Xe isotopic ratios were all air-like suggesting that primary MORB signatures have been completely overprinted by air and/or seawater interaction. In contrast, 3He/4He ratios obtained by crushing indicate that a mantle helium component is still preserved, and 40Ar/36Ar values are affected by radiogenic decay in the mineral phases. The 130Xe/36Ar and 84Kr/36Ar ratios are respectively up to 15 times and 5 times higher than those of seawater and the highest ratios are found in samples affected by low temperature alteration (shallower than 800-900 m sub-basement). We consider three possible processes: (i) adsorption onto the clays present in the samples; (ii) fluid inclusions with a marine pore fluid composition; and (iii) fractionation of seawater through phase separation caused by boiling. Ninety percent of the Cl, Br and I were released during the heating experiments, showing that halogens are dominantly held in mineral phases prior to subduction. I/Cl ratios vary by 4 orders of magnitude, from 3 × 10-6 to 2 × 10-2. The mean Br/Cl ratio is 30% lower than in MORB and seawater. I/Cl ratios lower than MORB values are attributed to Cl-rich amphibole formation caused by hydrothermal alteration at depths greater than 800-900 m sub-basement together with different extents of I loss during low and high temperature alteration. At shallower depths, I

  12. Noble gas isotopes in mineral springs and wells within the Cascadia forearc, Washington, Oregon, and California

    USGS Publications Warehouse

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

    2017-01-31

    IntroductionThis U.S. Geological Survey report presents laboratory analyses along with field notes for an exploratory study to document the relative abundance of noble gases in mineral springs and water wells within the Cascadia forearc of Washington, Oregon, and California (fig. 1). This report describes 14 samples collected in 2014 and 2015 and complements a previous report that describes 9 samples collected in 2012 and 2013 (McCrory and others, 2014b). Estimates of the depth to the underlying Juan de Fuca oceanic plate beneath sample sites are derived from the McCrory and others (2012) slab model. Some of the springs have been previously sampled for chemical analyses (Mariner and others, 2006), but none of the springs or wells currently has publicly available noble gas data. The helium and neon isotope values and ratios presented below are used to determine the sources and mixing history of these mineral and well waters (for example, McCrory and others, 2016).

  13. Novel Wavelength Shifting Collection Systems for Vacuum Ultraviolet Scintillation Photons in in Noble Gas Detectors

    NASA Astrophysics Data System (ADS)

    Gehman, Victor

    2013-04-01

    Detection of vacuum ultraviolet (VUV) photons presents a challenge because this band of the electromagnetic spectrum has a short enough wavelength to scatter off of most (though not all) materials, but is not energetic enough to penetrate into the bulk of a detector (so cannot be treated calorimetrically like x rays or γ rays). This is exactly the band in which noble gasses (which make excellent media for radiation detectors) scintillate. VUV photon detection usually involves shifting them to visible wavelengths with a fluorescent molecule deposited on an optically clear surface viewed by a photosensor. Such techniques, while comparatively efficient and simple to fabricate, have high cost and complexity per unit coverage area making them prohibitively expensive and complicated to scale up to the very large sizes necessary for the next generation of neutrino, dark matter, and other rare event search experiments. We present several lines of inquiry attempting to address this problem, focusing on solutions that are directly applicable to a variety of current or next generation noble gas detectors. This line of R&D is a potentially fruitful avenue capable of furthering the goals of many experiments with a broad portfolio of fundamental and applied research.

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

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  15. 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.

  16. Noble gas and hydrocarbon tracers in multiphase unconventional hydrocarbon systems: Toward integrated advanced reservoir simulators

    NASA Astrophysics Data System (ADS)

    Darrah, T.; Moortgat, J.; Poreda, R. J.; Muehlenbachs, K.; Whyte, C. J.

    2015-12-01

    Although hydrocarbon production from unconventional energy resources has increased dramatically in the last decade, total unconventional oil and gas recovery from black shales is still less than 25% and 9% of the totals in place, respectively. Further, the majority of increased hydrocarbon production results from increasing the lengths of laterals, the number of hydraulic fracturing stages, and the volume of consumptive water usage. These strategies all reduce the economic efficiency of hydrocarbon extraction. The poor recovery statistics result from an insufficient understanding of some of the key physical processes in complex, organic-rich, low porosity formations (e.g., phase behavior, fluid-rock interactions, and flow mechanisms at nano-scale confinement and the role of natural fractures and faults as conduits for flow). Noble gases and other hydrocarbon tracers are capably of recording subsurface fluid-rock interactions on a variety of geological scales (micro-, meso-, to macro-scale) and provide analogs for the movement of hydrocarbons in the subsurface. As such geochemical data enrich the input for the numerical modeling of multi-phase (e.g., oil, gas, and brine) fluid flow in highly heterogeneous, low permeability formations Herein we will present a combination of noble gas (He, Ne, Ar, Kr, and Xe abundances and isotope ratios) and molecular and isotopic hydrocarbon data from a geographically and geologically diverse set of unconventional hydrocarbon reservoirs in North America. Specifically, we will include data from the Marcellus, Utica, Barnett, Eagle Ford, formations and the Illinois basin. Our presentation will include geochemical and geological interpretation and our perspective on the first steps toward building an advanced reservoir simulator for tracer transport in multicomponent multiphase compositional flow (presented separately, in Moortgat et al., 2015).

  17. Numerical models, geochemistry and the zero-paradox noble-gas mantle.

    PubMed

    Ballentine, Chris J; Van Keken, Peter E; Porcelli, Don; Hauri, Erik H

    2002-11-15

    Numerical models of whole-mantle convection demonstrate that degassing of the mantle is an inefficient process, resulting in ca. 50% of the (40)Ar being degassed from the mantle system. In this sense the numerical simulations are consistent with the (40)Ar mass balance between the atmosphere and mantle reservoir. These models, however, are unable to preserve the large-scale heterogeneity predicted by models invoking geochemical layering of the mantle system. We show that the three most important noble-gas constraints on the geochemically layered mantle are entirely dependent on the (3)He concentration of the convecting mantle derived from the (3)He flux into the oceans and the average ocean-crust generation rate. A factor of 3.5 increase in the convecting-mantle noble-gas concentration removes all requirements for: a (3)He flux into the upper mantle from a deeper high (3)He source; a boundary in the mantle capable of separating heat from helium; and a substantial deep-mantle reservoir to contain a hidden (40)Ar rich reservoir. We call this model concentration for the convecting mantle the 'zero-paradox' concentration. The time-integrated flux of (3)He into the oceans is a robust observation, but only representative of the ocean-floor activity over the last 1000 years. In contrast, ocean-floor generation occurs over tens of millions of years. We argue that combining these two observations to obtain the (3)He concentration of the mantle beneath mid-ocean ridges is unsound. Other indicators of mantle (3)He concentration suggest that the real value may be at least a factor of two higher. As the zero-paradox concentration is approached, the noble-gas requirement for mantle layering is removed. We further consider the role that recycled material plays in ocean-island-basalt generation and show that a source with high (3)He and (3)He/(4)He must exist within the mantle. Nevertheless, only a small amount of this material is required to generate both the observed ocean

  18. Noble gas as tracers for CO2 deep input in petroleum reservoirs

    NASA Astrophysics Data System (ADS)

    Pujol, Magali; Stuart, Finlay; Gilfillan, Stuart; Montel, François; Masini, Emmanuel

    2016-04-01

    The sub-salt hydrocarbon reservoirs in the deep offshore part of the Atlantic Ocean passive margins are a new key target for frontier oil and gas exploration. Type I source rocks locally rich in TOC (Total Organic Carbon) combined with an important secondary connected porosity of carbonate reservoirs overlain by an impermeable salt layer gives rise to reservoirs with high petroleum potential. However, some target structures have been found to be mainly filled with CO2 rich fluids. δ13C of the CO2 is generally between -9 and -4 permil, compatible with a deep source (metamorphic or mantle). Understanding the origin of the CO2 and the relative timing of its input into reservoir layers in regard to the geodynamic context appears to be a key issue for CO2 risk evaluation. The inertness and ubiquity of noble gases in crustal fluids make them powerful tools to trace the origin and migration of mixed fluids (Ballentine and Burnard 2002). The isotopic signature of He, Ne and Ar and the elemental pattern (He to Xe) of reservoir fluid from pressurized bottom hole samples provide an insight into fluid source influences at each reservoir depth. Three main end-members can be mixed into reservoir fluids (e.g. Gilfillan et al., 2008): atmospheric signature due to aquifer recharge, radiogenic component from organic fluid ± metamorphic influence, and mantle input. Their relative fractionation provides insights into the nature of fluid transport (Burnard et al., 2012)and its relative migration timing. In the studied offshore passive margin reservoirs, from both sides of South Atlantic margin, a strong MORB-like magmatic CO2 influence is clear. Hence, CO2 charge must have occurred during or after lithospheric break-up. CO2 charge(s) history appears to be complex, and in some cases requires several inputs to generate the observed noble gas pattern. Combining the knowledge obtained from noble gas (origin, relative timing, number of charges) with organic geochemical and thermodynamic

  19. Assessing Compositional Variability and Migration of Natural Gas in the Antrim Shale in the Michigan Basin Using Noble Gas Geochemistry

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    The Antrim Shale was one of the first economic shale gas plays in the U.S. and has been actively produced since the 1980's. While previous studies suggest co-produced water in the Antrim is a mixture of brine from deeper formations and freshwater recharge, the extent of water-gas interactions has yet to be determined. The extent and source of thermogenic methane in the Antrim Shale are also under debate. This study uses stable noble gases' (He, Ne, Ar, Kr, Xe) isotopic ratios and their volume fractions from the Antrim Shale gases to assess compositional variability and vertical fluid migration, in addition to distinguishing between the presence of thermogenic versus biogenic methane. R/Ra values of Antrim Shale gases (where R and Ra are the measured and atmospheric 3He/4He ratios, respectively) vary from 0.01 to 0.34 suggesting dominant crustal 4He in addition to minor mantle and atmospheric He. Elevated 20Ne/22Ne ratios (up to 10.4) point to mantle Ne. Similarly crustal 21Ne*, 40Ar* and 136Xe* are also suggested. High variability of noble gas signatures in the Antrim Shale are observed, which are mainly due to variable noble gas input from deep brines and, to a smaller extent, variable in-situ production in the Antrim Shale. Estimated 4He ages considering external 4He flux for Antrim water match well with timings of three major glaciation periods (Wisconsin, Illinoian and Kansan glaciations) in the Michigan Basin, suggesting that all our Antrim samples were more or less influenced by glaciation recharge. Consistency in measured and predicted 40Ar/36Ar assuming Ar release temperatures ≥ 250°C supports a thermogenic origin for the majority of the methane in our Antrim Shale gas samples. Thermogenic methane is likely to originate at greater depth, either from deeper portions of the Antrim Shale in the central Michigan Basin or from deeper formations underlying the Antrim Shale, as the thermal maturity of the Antrim Shale in our study area is low.

  20. Using noble gas tracers to constrain a groundwater flow model with recharge elevations: A novel approach for mountainous terrain

    USGS Publications Warehouse

    Doyle, Jessica M.; Gleeson, Tom; Manning, Andrew H.; Mayer, K. Ulrich

    2015-01-01

    Environmental tracers provide information on groundwater age, recharge conditions, and flow processes which can be helpful for evaluating groundwater sustainability and vulnerability. Dissolved noble gas data have proven particularly useful in mountainous terrain because they can be used to determine recharge elevation. However, tracer-derived recharge elevations have not been utilized as calibration targets for numerical groundwater flow models. Herein, we constrain and calibrate a regional groundwater flow model with noble-gas-derived recharge elevations for the first time. Tritium and noble gas tracer results improved the site conceptual model by identifying a previously uncertain contribution of mountain block recharge from the Coast Mountains to an alluvial coastal aquifer in humid southwestern British Columbia. The revised conceptual model was integrated into a three-dimensional numerical groundwater flow model and calibrated to hydraulic head data in addition to recharge elevations estimated from noble gas recharge temperatures. Recharge elevations proved to be imperative for constraining hydraulic conductivity, recharge location, and bedrock geometry, and thus minimizing model nonuniqueness. Results indicate that 45% of recharge to the aquifer is mountain block recharge. A similar match between measured and modeled heads was achieved in a second numerical model that excludes the mountain block (no mountain block recharge), demonstrating that hydraulic head data alone are incapable of quantifying mountain block recharge. This result has significant implications for understanding and managing source water protection in recharge areas, potential effects of climate change, the overall water budget, and ultimately ensuring groundwater sustainability.

  1. Using noble gas tracers to constrain a groundwater flow model with recharge elevations: A novel approach for mountainous terrain

    NASA Astrophysics Data System (ADS)

    Doyle, Jessica M.; Gleeson, Tom; Manning, Andrew H.; Mayer, K. Ulrich

    2015-10-01

    Environmental tracers provide information on groundwater age, recharge conditions, and flow processes which can be helpful for evaluating groundwater sustainability and vulnerability. Dissolved noble gas data have proven particularly useful in mountainous terrain because they can be used to determine recharge elevation. However, tracer-derived recharge elevations have not been utilized as calibration targets for numerical groundwater flow models. Herein, we constrain and calibrate a regional groundwater flow model with noble-gas-derived recharge elevations for the first time. Tritium and noble gas tracer results improved the site conceptual model by identifying a previously uncertain contribution of mountain block recharge from the Coast Mountains to an alluvial coastal aquifer in humid southwestern British Columbia. The revised conceptual model was integrated into a three-dimensional numerical groundwater flow model and calibrated to hydraulic head data in addition to recharge elevations estimated from noble gas recharge temperatures. Recharge elevations proved to be imperative for constraining hydraulic conductivity, recharge location, and bedrock geometry, and thus minimizing model nonuniqueness. Results indicate that 45% of recharge to the aquifer is mountain block recharge. A similar match between measured and modeled heads was achieved in a second numerical model that excludes the mountain block (no mountain block recharge), demonstrating that hydraulic head data alone are incapable of quantifying mountain block recharge. This result has significant implications for understanding and managing source water protection in recharge areas, potential effects of climate change, the overall water budget, and ultimately ensuring groundwater sustainability.

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

    PubMed

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

    2012-01-01

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

  3. Detection of a Noble Gas Molecular Ion, 36ArH+, in the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Barlow, M. J.; Swinyard, B. M.; Owen, P. J.; Cernicharo, J.; Gomez, H. L.; Ivison, R. J.; Krause, O.; Lim, T. L.; Matsuura, M.; Miller, S.; Olofsson, G.; Polehampton, E. T.

    2013-12-01

    Noble gas molecules have not hitherto been detected in space. From spectra obtained with the Herschel Space Observatory, we report the detection of emission in the 617.5- and 1234.6-gigahertz J = 1-0 and 2-1 rotational lines of 36ArH+ at several positions in the Crab Nebula, a supernova remnant known to contain both molecular hydrogen and regions of enhanced ionized argon emission. Argon-36 is believed to have originated from explosive nucleosynthesis in massive stars during core-collapse supernova events. Its detection in the Crab Nebula, the product of such a supernova event, confirms this expectation. The likely excitation mechanism for the observed 36ArH+ emission lines is electron collisions in partially ionized regions with electron densities of a few hundred per centimeter cubed.

  4. Imaging the impulsive alignment of noble-gas dimers via Coulomb explosion

    NASA Astrophysics Data System (ADS)

    Veltheim, A. von; Borchers, B.; Steinmeyer, G.; Rottke, H.

    2014-02-01

    The impulsive alignment of the noble-gas dimers Ne2, Ar2, Kr2, and Xe2 is experimentally investigated by determining the alignment through Coulomb explosion imaging after their double ionization. This approach yields a favorably detailed insight into the temporal evolution of the alignment succeeding the aligning laser pulse. Particular emphasis is put on analyzing higher order coherences induced in the density matrix as these coherences determine the details of the temporal evolution of the aligned molecular ensemble. The recorded data enable an extraction of polarizability anisotropies for the dimers and of their rotational constants in the vibrational ground state. At the elevated level of rotational excitation obtained, centrifugal distortion starts influencing the temporal evolution of the alignment.

  5. Delineation of Fast Flow Paths in Porous Media Using Noble Gas Tracers

    SciTech Connect

    Hudson, G B; Moran, J E

    2002-03-21

    Isotopically enriched xenon isotopes are ideal for tracking the flow of relatively large volumes of groundwater. Dissolved noble gas tracers behave conservatively in the saturated zone, pose no health risk to drinking water supplies, and can be used with a large dynamic range. Different Xe isotopes can be used simultaneously at multiple recharge sources in a single experiment. Results from a tracer experiment at a California water district suggests that a small fraction of tracer moved from the recharge ponds through the thick, unconfined, coarse-grained alluvial aquifer to high capacity production wells at a horizontal velocity of 6 m/day. In contrast, mean water residence times indicate that the average rate of transport is 0.5 to 1 m/day.

  6. Mechanoluminescence of terbium and cerium sulfates in a noble-gas atmosphere

    NASA Astrophysics Data System (ADS)

    Tukhbatullin, A. A.; Sharipov, G. L.; Abdrakhmanov, A. M.; Muftakhutdinov, M. R.

    2014-05-01

    Lines of Ne (3 p-3 s, 550-800 nm) and Xe (6 p-6 s, 800-1050 nm; 7 p-6 s, 475 nm) have been detected in the mechanoluminescence spectrum of terbium and cerium sulfate crystallohydrates. The luminescence of noble gas is observed jointly with the known bands of Ce3+ and Tb3+ ions and N*2 lines. The lines corresponding to excited Xe+ ions (500-550 nm), indicative of achievement of electric-field strengths on the order of 107 V/cm during mechanoluminescence, are also observed. It is established that, during mechanoluminescence of Tb2(SO4)3 · 8D2O in an argon atmosphere under a pressure of 1.3 atm, mechanochemical reactions of decomposition of crystallization water (D2O) molecules cause luminescence of OD radicals; this luminescence is initiated by electron impact occurring during electrization and in discharges in crystals during destruction.

  7. Infrared and density functional theory studies of formic acid hydrate clusters in noble gas matrices

    NASA Astrophysics Data System (ADS)

    Ito, Fumiyuki

    2016-08-01

    Infrared absorption spectra of formic acid hydrate clusters (HCOOH)m(H2O)n have been measured in noble gas matrices (Ar and Kr). The concentration dependence of the spectra and the comparison with a previous experimental study on HCOOH(H2O) and HCOOH(H2O)2 [Geoge et al., Spectrochim. Acta, Part A 60 (2004) 3225] led to the identification of large clusters. Density functional theory calculations at the B3LYP-DCP/6-31+G(2d,2p) level were carried out to determine the anharmonic vibrational properties of the clusters, enabling a consistent assignment of the observed vibrational peaks to specific clusters.

  8. Solar wind neon from Genesis: implications for the lunar noble gas record.

    PubMed

    Grimberg, Ansgar; Baur, Heinrich; Bochsler, Peter; Bühler, Fritz; Burnett, Donald S; Hays, Charles C; Heber, Veronika S; Jurewicz, Amy J G; Wieler, Rainer

    2006-11-17

    Lunar soils have been thought to contain two solar noble gas components with distinct isotopic composition. One has been identified as implanted solar wind, the other as higher-energy solar particles. The latter was puzzling because its relative amounts were much too large compared with present-day fluxes, suggesting periodic, very high solar activity in the past. Here we show that the depth-dependent isotopic composition of neon in a metallic glass exposed on NASA's Genesis mission agrees with the expected depth profile for solar wind neon with uniform isotopic composition. Our results strongly indicate that no extra high-energy component is required and that the solar neon isotope composition of lunar samples can be explained as implantation-fractionated solar wind.

  9. Detection of a noble gas molecular ion, 36ArH+, in the Crab Nebula.

    PubMed

    Barlow, M J; Swinyard, B M; Owen, P J; Cernicharo, J; Gomez, H L; Ivison, R J; Krause, O; Lim, T L; Matsuura, M; Miller, S; Olofsson, G; Polehampton, E T

    2013-12-13

    Noble gas molecules have not hitherto been detected in space. From spectra obtained with the Herschel Space Observatory, we report the detection of emission in the 617.5- and 1234.6-gigahertz J = 1-0 and 2-1 rotational lines of (36)ArH(+) at several positions in the Crab Nebula, a supernova remnant known to contain both molecular hydrogen and regions of enhanced ionized argon emission. Argon-36 is believed to have originated from explosive nucleosynthesis in massive stars during core-collapse supernova events. Its detection in the Crab Nebula, the product of such a supernova event, confirms this expectation. The likely excitation mechanism for the observed (36)ArH(+) emission lines is electron collisions in partially ionized regions with electron densities of a few hundred per centimeter cubed.

  10. Noble gas thermometry and hydrologic ages: Evidence for late Holocene warming in Southwest Texas

    NASA Astrophysics Data System (ADS)

    Castro, Maria Clara; Goblet, Patrick

    2003-12-01

    Paleoclimatic reconstruction using noble gas concentrations in the Carrizo aquifer of southwest Texas and water ages determined through simulation of groundwater age reveals abrupt late Holocene temperature increases previously unidentified through 14C dating. Of particular interest is a temperature increase of up to 3.4°C in the first half of the last millennium following a cold period between ~3.7 and 0.9 Kyrs BP. Wet, cool periods in the region are associated with El-Nino dominated conditions, while warm, arid events are linked to multi-decade La-Nina dominant events. The data shows a slow decrease in temperature between ~1,200 and 200 Kyrs BP, a decrease that accelerated in the late Pleistocene and early Holocene. This decrease was followed by warming in the last millennium, that seems to be continuing today.

  11. Noble-gas geochemistry of the M7.2 earthquake close to Lake Van (Turkey)

    NASA Astrophysics Data System (ADS)

    Tomonaga, Y.; Brennwald, M. S.; Maden, C.; Meydan, A.; Kipfer, R.

    2013-12-01

    Terrigenic He release and changes in the He isotope ratio in response to tectonic activity are well known geochemical responses to tectonic activity. However, the very local nature of the He release from the solid earth implies that every system considered has to be addressed as a single and unique entity. Only such case-specific assessment allows to infer possible links between geochemistry and major seismic events. Our research in Lake Van (Turkey) during the last two decades sets a solid experimental basis to evaluate and interpret possible changes in the noble gas isotope composition in the water column induced by the devastating earthquake of magnitude 7.2 occurred on Oct. 23rd 2011 close to the city of Van. Lake Van is one of the largest terminal lakes and the largest soda lake on Earth. The lake basin is situated in a tectonically active region characterized by the presence of major faults and volcanoes and is known to accumulate mantle fluids. As during the last years the deep-water mixing of Lake Van is suppressed by a salinity-driven stabilization due to a lake level rise, the geochemical signature of fluids released in relation to this major earthquake is expected to accumulate and to be preserved in the water body for a certain period of time being defined by the slow but still ongoing water exchange due to turbulent mixing. In this work we present the noble-gas concentrations of water samples from Lake Van acquired before and after the earthquake. For the first time the accumulation of terrigenic He with a strong crustal He isotope signature coupled with warm fluids is observed in Lake Van. The injection of crustal He has to be considered as a sudden event that started at least in 2010. The observed anomalies can be produced only by forcing crustal fluids into the lake whereby the recent high tectonic activity is most likely the key process that triggered such a release of geogenic fluids. Our findings indicate that noble gases could be promising

  12. Reservoir Characterization using geostatistical and numerical modeling in GIS with noble gas geochemistry

    NASA Astrophysics Data System (ADS)

    Vasquez, D. A.; Swift, J. N.; Tan, S.; Darrah, T. H.

    2013-12-01

    The integration of precise geochemical analyses with quantitative engineering modeling into an interactive GIS system allows for a sophisticated and efficient method of reservoir engineering and characterization. Geographic Information Systems (GIS) is utilized as an advanced technique for oil field reservoir analysis by combining field engineering and geological/geochemical spatial datasets with the available systematic modeling and mapping methods to integrate the information into a spatially correlated first-hand approach in defining surface and subsurface characteristics. Three key methods of analysis include: 1) Geostatistical modeling to create a static and volumetric 3-dimensional representation of the geological body, 2) Numerical modeling to develop a dynamic and interactive 2-dimensional model of fluid flow across the reservoir and 3) Noble gas geochemistry to further define the physical conditions, components and history of the geologic system. Results thus far include using engineering algorithms for interpolating electrical well log properties across the field (spontaneous potential, resistivity) yielding a highly accurate and high-resolution 3D model of rock properties. Results so far also include using numerical finite difference methods (crank-nicholson) to solve for equations describing the distribution of pressure across field yielding a 2D simulation model of fluid flow across reservoir. Ongoing noble gas geochemistry results will also include determination of the source, thermal maturity and the extent/style of fluid migration (connectivity, continuity and directionality). Future work will include developing an inverse engineering algorithm to model for permeability, porosity and water saturation.This combination of new and efficient technological and analytical capabilities is geared to provide a better understanding of the field geology and hydrocarbon dynamics system with applications to determine the presence of hydrocarbon pay zones (or

  13. Methane Sources and Migration Mechanisms in the Shallow Trinity Aquifer in Parker and Hood Counties, Texas - a Noble Gas Analysis

    NASA Astrophysics Data System (ADS)

    Wen, T.; Castro, C.; Nicot, J. P.; Hall, C. M.; Mickler, P. J.; Darvari, R.

    2016-12-01

    The presence of elevated methane in groundwaters within the Barnett Shale footprint in Parker and Hood counties, Texas has caused public concern that hydrocarbon production may facilitate migration of natural gas into a critical groundwater resource. This study places constraints on the source of methane in these groundwaters by analyzing water and stray gas data from groundwater wells and gas production wells from both the Barnett Shale and Strawn Group for methane content and noble gases, both of crustal and atmospheric origin. Particular emphasis is given to the atmospheric heavier noble gases 84Kr and 132Xe, which are significantly less affected by the presence of excess air, commonly present in modern Texas groundwaters (e.g., [1]). Dissolved methane concentrations are positively correlated with crustal 4He, 21Ne and 40Ar and suggest that noble gases and methane in these groundwaters originate from a common source, likely the Strawn Group, which the sampled aquifer overlies unconformably. This finding is further supported by the noble gas isotopic signature of stray gas when compared to the gas isotopic signatures of both Barnett Shale and the Strawn Group. In contrast to most samples, four groundwater wells with the highest methane concentrations unequivocally show heavy depletion of the atmospheric noble gases 20Ne, 36Ar, 84Kr and 132Xe with respect to freshwater recharge equilibrated with the atmosphere (ASW). This is consistent with predicted noble gas concentrations in a residual water phase in contact with a gas phase with initial ASW composition at 18°C-25°C, assuming a closed-system and suggest a highly localized gas source. All these four wells, without exception, tap into the Strawn Group and it is likely that shallow gas accumulations, as they are known to exist, were reached. Additionally, lack of correlation between 84Kr/36Ar and 132Xe/36Ar fractionation levels and distance to the nearest production wells does not support the notion that methane

  14. Using Noble Gas Geochemistry to Determine the Source and Mechanism of Natural Gas Leakage into Shallow Aquifers Near Unconventional Drilling

    NASA Astrophysics Data System (ADS)

    Darrah, T.; Whyte, C. J.

    2015-12-01

    Horizontal drilling and hydraulic fracturing have enhanced energy production but raised concerns about drinking-water contamination and other environmental impacts associated with unconventional energy development. The occurrence of fugitive gas contamination in drinking-water wells near unconventional natural gas development has been central to the debate about the environmental impacts of hydraulic fracturing, but still has a controversial origin that has variably been attributed to natural geogenic occurrences, poor well bore integrity, and crustal-scale migration of natural gas along natural deformation features. Differentiating amongst these possibilities is critical to ongoing efforts to understand the environmental implications for the presence of elevated methane and aliphatic hydrocarbons (ethane, propane, etc.) in drinking-water and a necessary step toward the development of implementable solutions that limit the occurrence of future fugitive gas events. Here we will expand upon our recent work in the Marcellus and Barnett gas fields (Jackson et al., 2013; Darrah et al., 2014; 2015) that developed noble gas techniques for distinguishing natural and anthropogenic mechanisms of natural gas migration by integrating the molecular and isotopic composition of non-hydrocarbon molecules (N2, H2S, CO2) in addition to compound specific isotopes of hydrocarbons (d2H of CH4 and d2H-C2H6 and d13C of CH4, C2H6, and C3H8) and non-hydrocarbon compounds (d15N-N2). The expanded data sets validate our initial study and support the hypothesis that a subset of drinking-water wells experience natural gas contamination following faulty well construction or poor well integrity amid a background of naturally occurring gas and salt-rich groundwater.

  15. 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

  16. 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.

  17. U.S. Geological Survey Noble Gas Laboratory’s standard operating procedures for the measurement of dissolved gas in water samples

    USGS Publications Warehouse

    Hunt, Andrew G.

    2015-08-12

    This report addresses the standard operating procedures used by the U.S. Geological Survey’s Noble Gas Laboratory in Denver, Colorado, U.S.A., for the measurement of dissolved gases (methane, nitrogen, oxygen, and carbon dioxide) and noble gas isotopes (helium-3, helium-4, neon-20, neon-21, neon-22, argon-36, argon-38, argon-40, kryton-84, krypton-86, xenon-103, and xenon-132) dissolved in water. A synopsis of the instrumentation used, procedures followed, calibration practices, standards used, and a quality assurance and quality control program is presented. The report outlines the day-to-day operation of the Residual Gas Analyzer Model 200, Mass Analyzer Products Model 215–50, and ultralow vacuum extraction line along with the sample handling procedures, noble gas extraction and purification, instrument measurement procedures, instrumental data acquisition, and calculations for the conversion of raw data from the mass spectrometer into noble gas concentrations per unit mass of water analyzed. Techniques for the preparation of artificial dissolved gas standards are detailed and coupled to a quality assurance and quality control program to present the accuracy of the procedures used in the laboratory.

  18. Detecting gas molecules via atomic magnetization.

    PubMed

    Choi, Heechae; Lee, Minho; Kim, Seungchul; Lee, Kwang-Ryeol; Chung, Yong-Chae

    2014-09-14

    Adsorptions of gas molecules were found to alter the directions and magnitudes of magnetic moments of transition metal (Co, Fe) atoms adsorbed on graphene. Using first-principles calculations, we demonstrated that magnetism of surface atoms can be used to identify the kind of existing gas molecules via spin-reorientation and/or demagnetizations caused by the reconfigurations of 3d electron energy levels of Co and Fe. We suggest for the first time that magnetic properties of transition metal-embedded nanostructures can be used in highly selective gas-sensing applications.

  19. A search for noble-gas evidence for presolar oxide grains

    NASA Technical Reports Server (NTRS)

    Lewis, Roy S.; Srinivasan, B.

    1993-01-01

    Early results from an ongoing search for isotopically distinctive noble gases as evidence for presolar oxide grains are presented. With some qualifications, we do not see such evidence in spinel rich acid residue fractions from the Allende meteorite. We remain hopeful that less abundant mineral separates may yet be fruitful. Presolar grains, micro-diamonds, silicon carbide, and graphite, were found in primitive meteorites. While the abundances of these three refractory C rich grains are low, a few hundred ppm, a few ppm, & less than 1 ppm, respectively in primitive meteorites, they are tagged with high concentrations of isotopically anomalous noble gas components, Xe-HL, KR & Xe-s and Ne-E(H), and Ne-E(L). These tags have served as tracers and allowed the development of techniques for their purification and eventual identification. One might expect similar amounts of refractory presolar oxides to have survived, but so far only three cases exist for their identification. The first two cases are individual corundum oxide grains. Huss et al. found one such grain from an Orgueil residue with an Al-26/Al-27 ratio of 8.9 x 10(exp -5), about 18 times higher than the canonical initial solar system value. The second corundum grain, from Murchison, was found by Nittler et al. to have unusual oxygen in addition to a similar Al-26/Al-27 ratio of 8.7 x 10(exp -4). The oxygen was depleted in O-18 by 22 percent and enriched in O-17 by a factor of 2. The third case is a measurement by Zinner et al. on an aggregate of fine grained spinels from a Murray residue with an O-17 enrichment and a possible O-18 depletion similar to the second grain, but much subdued. This is consistent with a few such presolar grains diluted by a much larger population of isotopically normal corundum grains and an even larger number of normal spinel grains.

  20. 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

    2015-06-01

    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.

  1. The role of soil air composition for noble gas tracer applications in tropical groundwater

    NASA Astrophysics Data System (ADS)

    Mayer, Simon; Jenner, Florian; Aeschbach, Werner; Weissbach, Therese; Peregovich, Bernhard; Machado, Carlos

    2016-04-01

    Dissolved noble gases (NGs) in groundwater provide a well-established tool for paleo temperature reconstruction. However, reliable noble gas temperature (NGT) determination needs appropriate assumptions or rather an exact knowledge of soil air composition. Deviations of soil air NG partial pressures from atmospheric values have already been found in mid latitudes during summer time as a consequence of subsurface oxygen depletion. This effect depends on ambient temperature and humidity and is thus expected to be especially strong in humid tropical soils, which was not investigated so far. We therefore studied NGs in soil air and shallow groundwater near Santarém (Pará, Brazil) at the end of the rainy and dry seasons, respectively. Soil air data confirms a correlation between NG partial pressures, the sum value of O2+CO2 and soil moisture contents. During the rainy season, we find significant NG enhancements in soil air by up to 7% with respect to the atmosphere. This is twice as much as observed during the dry season. Groundwater samples show neon excess values between 15% and 120%. Nearly all wells show no seasonal variations of excess air, even though the local river level seasonally fluctuates by about 8 m. Assuming atmospheric NG contents in soil air, fitted NGTs underestimate the measured groundwater temperature by about 1-2° C. However, including enhanced soil air NG contents as observed during the rainy season, resulting NGTs are in good agreement with local groundwater temperatures. Our presented data allows for a better understanding of subsurface NG variations. This is essential with regard to NG tracer applications in humid tropical areas, for which reliable paleoclimate data is of major importance for modern climate research.

  2. Unprecedented Enhancement of Noble Gas-Noble Metal Bonding in NgAu3(+) (Ng = Ar, Kr, and Xe) Ion through Hydrogen Doping.

    PubMed

    Ghosh, Ayan; Ghanty, Tapan K

    2016-12-22

    Behavior of gold as hydrogen in certain gold compounds and a very recent experimental report on the noble gas-noble metal interaction in Ar complexes of mixed Au-Ag trimers have motivated us to investigate the effect of hydrogen doping on the Ng-Au (Ng = Ar, Kr, and Xe) bonding through various ab initio based techniques. The calculated results show considerable strengthening of the Ng-Au bond in terms of bond length, bond energy, stretching vibrational frequency, and force constant. Particularly, an exceptional enhancement of Ar-Au bonding strength has been observed in ArAuH2(+) species as compared to that in ArAu3(+) system, as revealed from the CCSD(T) calculated Ar-Au bond energy value of 32 and 72 kJ mol(-1) for ArAu3(+) and ArAuH2(+), respectively. In the calculated IR spectra, the Ar-Au stretching frequency is blue-shifted by 65% in going from ArAu3(+) to ArAuH2(+) species. Similar trends have been obtained in the case of all Ar, Kr, and Xe complexes with Ag and Cu trimers. Among all the NgM3-kHk(+) complexes (where k = 0-2), the strongest binding in NgMH2(+) complex is attributed to significant enhancement in the covalent characteristics of the Ng-M bond and considerable increase in charge-induced dipole interaction, as shown from the topological analysis.

  3. Metastability and structural polymorphism in noble metals: the role of composition and metal atom coordination in mono- and bimetallic nanoclusters.

    PubMed

    Sanchez, Sergio I; Small, Matthew W; Bozin, Emil S; Wen, Jian-Guo; Zuo, Jian-Min; Nuzzo, Ralph G

    2013-02-26

    This study examines structural variations found in the atomic ordering of different transition metal nanoparticles synthesized via a common, kinetically controlled protocol: reduction of an aqueous solution of metal precursor salt(s) with NaBH₄ at 273 K in the presence of a capping polymer ligand. These noble metal nanoparticles were characterized at the atomic scale using spherical aberration-corrected scanning transmission electron microscopy (C(s)-STEM). It was found for monometallic samples that the third row, face-centered-cubic (fcc), transition metal [(3M)-Ir, Pt, and Au] particles exhibited more coherently ordered geometries than their second row, fcc, transition metal [(2M)-Rh, Pd, and Ag] analogues. The former exhibit growth habits favoring crystalline phases with specific facet structures while the latter samples are dominated by more disordered atomic arrangements that include complex systems of facets and twinning. Atomic pair distribution function (PDF) measurements further confirmed these observations, establishing that the 3M clusters exhibit longer ranged ordering than their 2M counterparts. The assembly of intracolumn bimetallic nanoparticles (Au-Ag, Pt-Pd, and Ir-Rh) using the same experimental conditions showed a strong tendency for the 3M atoms to template long-ranged, crystalline growth of 2M metal atoms extending up to over 8 nm beyond the 3M core.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    Hydrochemical, stable isotopic (δ18O and δD) and noble gas isotopic analyses of seven geothermal water samples, eleven groundwater samples and six surface water samples collected from the Icheon and Pocheon area were carried out to find out hydrochemical characteristics, and to interpret the source of noble gases and the geochemical evolution of the geothermal waters. The geothermal waters show low temperature type ranging from 21.5 to 31.4 ℃ and the pH value between 6.69 and 9.21. Electrical conductivity of geothermal waters has the range from 310 to 735 μS/cm. Whereas the geothermal in the Icheon area shows the geochemical characteristics of neutral pH, the Ca-HCO3(or Ca(Na)-HCO3) chemical type and a high uranium content, the geothermal water in the Pocheon area shows the characteristics of alkaline pH, the Na-HCO3 chemical type and a high fluorine content. These characteristics indicate that the geothermal water in the Icheon area is under the early stage in the geochemical evolution, and that geothermal water in the Pocheon area has been geochemically evolved. The δ18O and δD values of geothermal waters show the range of -10.1˜-8.69‰ and from -72.2˜-60.8‰, respectively, and these values supply the information of the recharge area of geothermal waters. The 3He/4He ratios of the geothermal waters range from 0.09×10-6 to 0.65×10-6 which are plotted above the mixing line between air and crustal components. Whereas the helium gas in the Icheon geothermal water was mainly provided from the atmospheric source mixing with the mantle(or magma) origin, the origin of helium gas in the Pocheon geothermal water shows a dominant crustal source. 40Ar/36Ar ratios of geothermal water are in the range of an atmosphere source. Key words: hot spring water, hydrochemical composition, low temperature type, 3He/4He ratios, crustal source

  5. Measuring the spin polarization of alkali-metal atoms using nuclear magnetic resonance frequency shifts of noble gases

    SciTech Connect

    Liu, X. H.; Luo, H.; Qu, T. L. Yang, K. Y.; Ding, Z. C.

    2015-10-15

    We report a novel method of measuring the spin polarization of alkali-metal atoms by detecting the NMR frequency shifts of noble gases. We calculated the profile of {sup 87}Rb D1 line absorption cross sections. We then measured the absorption profile of the sample cell, from which we calculated the {sup 87}Rb number densities at different temperatures. Then we measured the frequency shifts resulted from the spin polarization of the {sup 87}Rb atoms and calculated its polarization degrees at different temperatures. The behavior of frequency shifts versus temperature in experiment was consistent with theoretical calculation, which may be used as compensative signal for the NMRG closed-loop control system.

  6. Noble gas tracers of mantle processes beneath the Galápagos archipelago (Invited)

    NASA Astrophysics Data System (ADS)

    Kurz, M. D.; Harpp, K. S.; Geist, D.; Fornari, D. J.; Curtice, J.; Lott, D. E.; Jenkins, W. J.

    2010-12-01

    Recent measurements in dredged glassy basalts from the western and northern submarine edges of the Galápagos archipelago (R/V Revelle/Drift04 and R/V Melville/MV1007 expeditions, respectively) allow a new examination of the spatial distribution of the noble gas isotopic compositions. The large dynamic range in helium isotopic compositions (6.5 to 30 times atmosphere (Ra)) coupled with the spatial distribution of recent submarine and subaerial volcanism provides a unique picture of mantle dynamics. The highest 3He/4He in the Galápagos are found in basalts from Fernandina volcano at the western edge of the archipelago, which also has the most unradiogenic neon isotopic compositions, suggesting that Fernandina lies above the hotspot center. The high helium isotopic signal drops off asymmetrically to the north and south of Fernandina, with higher 3He/4He ratios found to the South, ranging from 10 to 20 Ra near Cerro Azul, Sierra Negra, and Floreana. To the north of Fernandina, 3He/4He ratios decrease rapidly, reaching values close to MORB at Volcan Ecuador (9.8 to 11.4 Ra), Volcan Wolf (8.1 to 9.2 Ra), and Roca Redonda (7.6 to 9.5 Ra). Preliminary data suggests that He, Ne, and Ar isotopes are correlated in basalts from the western edge of the Galápagos. Using neon isotope data to correct 40Ar/36Ar for atmospheric influence shows that 3He/4He is negatively correlated with (extrapolated) 40Ar/36Ar, and strongly suggests that the noble gas variations relate to mantle source, which has important implications for deep earth noble gas budgets. New data from seamounts in the area between the Galápagos Spreading Center (GSC) and the main archipelago reveal relatively small hotspot helium contributions. The region between the GSC and Isla Pinta is characterized by 3He/4He close to MORB (7.3 to 7.7 Ra). The only evidence of hotspot helium contributions is observed at the southernmost end of the Wolf Darwin Lineament (9.3 Ra) and at the shoal between Genovesa and Marchena (9

  7. Atomic gas in debris discs

    NASA Astrophysics Data System (ADS)

    Hales, Antonio S.; Barlow, M. J.; Crawford, I. A.; Casassus, S.

    2017-04-01

    We have conducted a search for optical circumstellar absorption lines in the spectra of 16 debris disc host stars. None of the stars in our sample showed signs of emission line activity in either Hα, Ca II or Na I, confirming their more evolved nature. Four stars were found to exhibit narrow absorption features near the cores of the photospheric Ca II and Na I D lines (when Na I D data were available). We analyse the characteristics of these spectral features to determine whether they are of circumstellar or interstellar origins. The strongest evidence for circumstellar gas is seen in the spectrum of HD 110058, which is known to host a debris disc observed close to edge-on. This is consistent with a recent ALMA detection of molecular gas in this debris disc, which shows many similarities to the β Pictoris system.

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

    PubMed

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

    2013-06-21

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

  9. Indigenous nitrogen in the Moon: Constraints from coupled nitrogen-noble gas analyses of mare basalts

    NASA Astrophysics Data System (ADS)

    Füri, Evelyn; Barry, Peter H.; Taylor, Lawrence A.; Marty, Bernard

    2015-12-01

    Nitrogen and noble gas (Ne-Ar) abundances and isotope ratios, determined by step-wise CO2 laser-extraction, static-mass spectrometry analysis, are reported for bulk fragments and mineral separates of ten lunar mare basalts (10020, 10057, 12008, 14053, 15555, 70255, 71557, 71576, 74255, 74275), one highland breccia (14321), and one ferroan anorthosite (15414). The mare basalt sub-samples 10057,183 and 71576,12 contain a large amount of solar noble gases, whereas neon and argon in all other samples are purely cosmogenic, as shown by their 21Ne/22Ne ratios of ≈0.85 and 36Ar/38Ar ratios of ≈0.65. The solar-gas-free basalts contain a two-component mixture of cosmogenic 15N and indigenous nitrogen (<0.5 ppm). Mare basalt 74255 and the olivine fraction of 15555,876 record the smallest proportion of 15Ncosm; therefore, their δ15 N values of -0.2 to + 26.7 ‰ (observed at the low-temperature steps) are thought to well represent the isotopic composition of indigenous lunar nitrogen. However, δ15 N values ≤ - 30 ‰ are found in several basalts, overlapping with the isotopic signature of Earth's primordial mantle or an enstatite chondrite-like impactor. While the lowest δ15 N values allow for nitrogen trapped in the Moon's interior to be inherited from the proto-Earth and/or the impactor, the more 15N-enriched compositions require that carbonaceous chondrites provided nitrogen to the lunar magma ocean prior to the solidification of the crust. Since nitrogen can efficiently be incorporated into mafic minerals (olivine, pyroxene) under oxygen fugacities close to or below the iron-wustite buffer (Li et al., 2013), the mare basalt source region is likely characterized by a high nitrogen storage capacity. In contrast, anorthosite 15414 shows no traces of indigenous nitrogen, suggesting that nitrogen was not efficiently incorporated into the lunar crust during magma ocean differentiation.

  10. 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

  11. [A possible molecular mechanism of the narcotic action of noble gases].

    PubMed

    Dovgusha, V V; Fok, M V; Zaritskaia, G A

    2005-01-01

    A molecular mechanism of the narcotic action of noble gases is suggested, which is based on the fact that noble gas atoms change the orientation of water molecules absorbed on the surface of axon membrane. The resulting change in the transmembrane potential deteriorates the propagation of nerve pulse.

  12. USGS-NoGaDat - A global dataset of noble gas concentrations and their isotopic ratios in volcanic systems

    USGS Publications Warehouse

    Abedini, Atosa A.; Hurwitz, S.; Evans, William C.

    2006-01-01

    The database (Version 1.0) is a MS-Excel file that contains close to 5,000 entries of published information on noble gas concentrations and isotopic ratios from volcanic systems in Mid-Ocean ridges, ocean islands, seamounts, and oceanic and continental arcs (location map). Where they were available we also included the isotopic ratios of strontium, neodymium, and carbon. The database is sub-divided both into material sampled (e.g., volcanic glass, different minerals, fumarole, spring), and into different tectonic settings (MOR, ocean islands, volcanic arcs). Included is also a reference list in MS-Word and pdf from which the data was derived. The database extends previous compilations by Ozima (1994), Farley and Neroda (1998), and Graham (2002). The extended database allows scientists to test competing hypotheses, and it provides a framework for analysis of noble gas data during periods of volcanic unrest.

  13. Noble gas isotope sites and mobility in mafic rocks and olivine

    NASA Astrophysics Data System (ADS)

    Tolstikhin, I.; Kamensky, I.; Tarakanov, S.; Kramers, J.; Pekala, M.; Skiba, V.; Gannibal, M.; Novikov, D.

    2010-02-01

    Important He and Ar isotope studies on rocks and minerals, relevant to the geochemical and degassing history of the Earth, are often hampered by insufficient knowledge of the retentivity of different types of sites in minerals (inclusions, matrix) for these species, and of the relative importance of radiogenic and trapped components and possible differences in their behavior. To identify sites of noble gas isotopes, shed some light on their origin and estimate their residence times in olivine, which is a mineral considered as a good natural sampler, we investigated 2.5 Ga old ultramafic rocks from the Monche Pluton (Kola Peninsula, north-east part of the Baltic shield) using several extraction methods: crushing, fusion, slow step-wise and rapid incremental heating. Previous studies indicated that these rocks contain mainly trapped noble gases; however, to constrain the possible contribution of in-situ generated radiogenic helium, U and Th concentrations were also measured in the samples. The helium release pattern obtained by relatively fast (˜1.5 h long) incremental heating of olivine includes three distinct release peaks for helium: a low-temperature (600 °C) l-peak, a middle (800-1100 °C) m-peak and a high-temperature (˜1400 °C) h-peak. However, helium extraction from a powdered aliquot of the same olivine yields mainly the middle m-peak indicating that gases released in the l- and h-peaks occupy gas-liquid inclusions opened in the course of crushing and grinding. Moreover, slow step-wise heating (14 h) also results in a broad He release peak but in two well-separated l- and h-peaks of non-atmospheric 40Ar∗. This feature implies helium migration from l- and h-vesicles into the matrix m during long step-wise heating experiments, whereas less movable Ar remains in inclusions at even relatively high almost-magmatic temperatures. Using a simple phenomenological model envisaging the three different residence sites for noble gases, both fast- and slow

  14. The degassing history of the Earth: Noble gas studies of Archaean cherts and zero age glassy submarine basalts

    NASA Technical Reports Server (NTRS)

    Hart, R.; Hogan, L.

    1985-01-01

    Recent noble gas studies suggests the Earth's atmosphere outgassed from the Earth's upper mantle synchronous with sea floor spreading, ocean ridge hydrothermal activity and the formation of continents by partial melting in subduction zones. The evidence for formation of the atmosphere by outgassing of the mantle is the presence of radionuclides H3.-4, Ar-040 and 136 Xe-136 in the atmosphere that were produced from K-40, U and Th in the mantle. How these radionuclides were formed is reviewed.

  15. The degassing history of the Earth: Noble gas studies of Archaean cherts and zero age glassy submarine basalts

    NASA Technical Reports Server (NTRS)

    Hart, R.; Hogan, L.

    1985-01-01

    Recent noble gas studies suggests the Earth's atmosphere outgassed from the Earth's upper mantle synchronous with sea floor spreading, ocean ridge hydrothermal activity and the formation of continents by partial melting in subduction zones. The evidence for formation of the atmosphere by outgassing of the mantle is the presence of radionuclides H3.-4, Ar-040 and 136 Xe-136 in the atmosphere that were produced from K-40, U and Th in the mantle. How these radionuclides were formed is reviewed.

  16. Above-threshold ionization of noble gases in elliptically polarized fields: Effects of atomic polarization on photoelectron angular distributions

    NASA Astrophysics Data System (ADS)

    Wang, YanLan; Yu, ShaoGang; Lai, XuanYang; Liu, XiaoJun; Chen, Jing

    2017-06-01

    We theoretically investigate the atomic polarization effect on photoelectron angular distributions (PADs) in above-threshold ionization of noble gases with elliptically polarized laser fields at wavelength of 800 nm, ellipticity of 0.25, and intensity of 1.5 ×1014W/cm2 . Simulations based on a semiclassical model that includes both the ionic Coulomb potential and the atomic polarization effect show surprisingly little difference between PADs for Ar, Kr, and Xe, which is in good agreement with recent experimental observations. Our calculations reveal that the atomic polarization effect increases the distance of the tunnel exit point of the photoelectron to the parent ion and weakens the strength of the interaction between the parent ion and the photoelectron on its subsequent classical propagation. As a result, the forward-scattering electrons which contribute to the main lobes in PADs are substantially suppressed. Our results indicate that the insensitivity of PADs for Ar, Kr, and Xe may be closely related to the influence of the atomic polarization effect on the photoelectron dynamics in the strong laser field.

  17. Making channeling visible: keV noble gas ion trails on Pt(111)

    NASA Astrophysics Data System (ADS)

    Redinger, A.; Standop, S.; Rosandi, Y.; Urbassek, H. M.; Michely, T.

    2011-01-01

    The impact of argon and xenon noble gas ions on Pt(111) in grazing incidence geometry are studied through direct comparison of scanning tunneling microscopy images and molecular dynamics simulations. The energy range investigated is 1-15 keV and the angles of incidence with respect to the surface normal are between 78.5° and 88°. The focus of the paper is on events where ions gently enter the crystal at steps and are guided in channels between the top most layers of the crystal. The trajectories of the subsurface channeled ions are visible as trails of surface damage. The mechanism of trail formation is analyzed using simulations and analytical theory. Significant differences between Xe+ and Ar+ projectiles in damage, in the onset energy of subsurface channeling as well as in ion energy dependence of trail length and appearance are traced back to the projectile and ion energy dependence of the stopping force. The asymmetry of damage production with respect to the ion trajectory direction is explained through the details of the channel shape and subchannel structure as calculated from the continuum approximation of the channel potential. Measured and simulated channel switching in directions normal and parallel to the surface as well as an increase of ions entering into channels from the perfect surface with increasing angles of incidence are discussed.

  18. Comparing Meteorite and Spacecraft Noble Gas Measurements to Trace Processes in the Martian Crust and Atmosphere

    NASA Astrophysics Data System (ADS)

    Swindle, T. D.

    2014-12-01

    Our knowledge of the noble gas abundances and isotopic compositions in the Martian crust and atmosphere come from two sources, measurements of meteorites from Mars and in situ measurements by spacecraft. Measurements by the Viking landers had large uncertainties, but were precise enough to tie the meteorites to Mars. Hence most of the questions we have are currently defined by meteorite measurements. Curiosity's SAM has confirmed that the Ar isotopic composition of the atmosphere is highly fractionated, presumably representing atmospheric loss that can now be modeled with more confidence. What turns out to be a more difficult trait to explain is the fact that the ratio of Kr/Xe in nakhlites, chassignites and ALH84001 is distinct from the atmospheric ratio, as defined by measurements from shergottites. This discrepancy has been suggested to be a result of atmosphere/groundwater/rock interaction, polar clathrate formation, or perhaps local temperature conditions. More detailed atmospheric measurements, along with targeted simulation experiments, will be needed to make full use of this anomaly.

  19. Noble gas systematics for coexisting glass and olivine crystals in basalts and dunite xenoliths from Loihi Seamount

    USGS Publications Warehouse

    Kaneoka, I.; Takaoka, N.; Clague, D.A.

    1983-01-01

    Noble gas isotopes including 3He 4He, 40Ar 36Ar and Xe isotope ratios were determined for coexisting glass and olivine crystals in tholeiitic and alkalic basalts and dunite xenoliths from Loihi Seamount. Glass and coexisting olivine crystals have similar 3He 4He ratios (2.8-3.4) ?? 10-5, 20 to 24 times the atmospheric ratio (RA), but different 40Ar 36Ar ratios (400-1000). Based on the results of noble gas isotope ratios and microscopic observation, some olivine crystals are xenocrysts. We conclude that He is equilibrated between glass and olivine xenocrysts, but Ar is not. The apparent high 3He 4He ratio (3 ?? 10-5; = 21 RA) coupled with a relatively high 40Ar 36Ar ratio (4200) for dunite xenoliths (KK 17-5) may be explained by equilibration of He between MORB-type cumulates and the host magma. Except for the dunite xenoliths, noble gas data for these Loihi samples are compatible with a model in which samples from hot spot areas may be explained by mixing between P (plume)-type and M (MORB)-type components with the addition of A (atmosphere)-type component. Excess 129Xe has not been observed due to apparent large mass fractionation among Xe isotopes. ?? 1983.

  20. Potential interstellar noble gas molecules: ArOH+ and NeOH+ rovibrational analysis from quantum chemical quartic force fields

    NASA Astrophysics Data System (ADS)

    Theis, Riley A.; Fortenberry, Ryan C.

    2016-03-01

    The discovery of ArH+ in the interstellar medium has shown that noble gas chemistry may be of more chemical significance than previously believed. The present work extends the known chemistry of small noble gas molecules to NeOH+ and ArOH+. Besides their respective neonium and argonium diatomic cation cousins, these hydroxyl cation molecules are the most stable small noble gas molecules analyzed of late. ArOH+ is once again more stable than the neon cation, but both are well-behaved enough for a complete quartic force field analysis of their rovibrational properties. The Ar-O bond in ArOH+ , for instance, is roughly three-quarters of the strength of the Ar-H bond in ArH+ highlighting the rigidity of this system. The rotational constants, geometries, and vibrational frequencies for both molecules and their various isotopologues are computed from ab initio quantum chemical theory at high-level, and it is shown that these cations may form in regions where peroxy or weakly-bound alcohols may be present. The resulting data should be of significant assistance for the laboratory or observational analysis of these potential interstellar molecules.

  1. Noble Gas Isotopic Evidence for Primordial Evolution of the Earth's Atmosphere in Three Distinct Stages

    NASA Astrophysics Data System (ADS)

    Harper, C. L., Jr.; Jacobsen, S. B.

    1995-09-01

    The deep Earth is the key to understanding the primordial evolution of the Earth's atmosphere. However the atmosphere was not derived by degassing of the Earth, as widely held. Isotopic characterization of mantle noble gases and modeling based on this information [1] suggests the atmosphere experienced a 3-stage early history. This follows from 5 basic observations: (i) Ne in the mantle is solar-like, with light (high) 20Ne/22Ne relative to the atmosphere [2]; (ii) mantle Xe has higher 128Xe/130Xe than the atmosphere [3], which carries an extreme heavy isotope enriched mass fractionation signature of >3%/amu (iii) most of the radiogenic Xe from l29I and 244Pu decay in the Earth is not present either in the mantle or in the atmosphere; (iv) the inferred abundances of noble gases in the deep Earth "plume source" are insufficient to generate the present atmospheric abundances, even for whole mantle degassing; and (v) mantle noble gases indicate a 2 component structure, with solar light gases (He and Ne) and planetary heavy gases [4]. The present day noble gas budgets (and likely also N2) must derive from late accretion of a volatile-rich "veneer." This is stage III. Stage II is a naked (no atmosphere) epoch indicated by evidence for Hadean degassing of 244Pu (T1/2 = 80 Ma) fission Xe from the whole mantle, which was not retained in the present atmosphere. The naked stage must have lasted for more than ~200 Ma, and was supported by the early intense solar EUV luminosity. Stage I, a massive solar-composition protoatmosphere, occurred during the Earth's early accretion phase. Its existence is indicated by the presence of the solar gas component in the Earth. This is not attributable to subduction of solar wind rich cosmic dust, or solar wind irradiation of coagulating objects. It is best explained by accretion of a solar composition atmosphere from the nebula. This provided a thermal blanket supporting a magma ocean in which solar gases dissolved. Under these conditions

  2. 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.

  3. Modulation by the noble gas argon of the catalytic and thrombolytic efficiency of tissue plasminogen activator.

    PubMed

    David, Hélène N; Haelewyn, Benoît; Risso, Jean-Jacques; Abraini, Jacques H

    2013-01-01

    Argon has been shown to provide cortical as well as, under certain conditions, subcortical neuroprotection in all models so far (middle cerebral artery occlusion, trauma, neonatal asphyxia, etc.). This has led to the suggestion that argon could be a cost-efficient alternative to xenon, a metabolically inert gas thought to be gold standard in gas pharmacology but whose clinical development suffers its little availability and excessive cost of production. However, whether argon interacts with the thrombolytic agent tissue plasminogen activator, which is the only approved therapy of acute ischemic stroke to date, still remains unknown. This latter point is not trivial since previous data have clearly demonstrated the inhibiting effect of xenon on tPA enzymatic and thrombolytic efficiency and the critical importance of the time at which xenon is administered, during or after ischemia, in order not to block thrombolysis and to obtain neuroprotection. Here, we investigated the effect of argon on tPA enzymatic and thrombolytic efficiency using in vitro methods shown to provide reliable prediction of the in vivo effects of both oxygen and the noble inert gases on tPA-induced thrombolysis. We found that argon has a concentration-dependent dual effect on tPA enzymatic and thrombolytic efficiency. Low and high concentrations of argon of 25 and 75 vol% respectively block and increase tPA enzymatic and thrombolytic efficiency. The possible use of argon at low and high concentrations in the treatment of acute ischemic stroke if given during ischemia or after tPA-induced reperfusion is discussed as regards to its neuroprotectant action and its inhibiting and facilitating effects on tPA-induced thrombolysis. The mechanisms of argon-tPA interactions are also discussed.

  4. Atom Probe Tomography Characterization of a Gas Atomized Metallic Glass

    SciTech Connect

    Miller, Michael K; Venkataraman, Shankar; Eckert, Jurgen; Schultz, Ludwig; Sordelet, Daniel

    2006-01-01

    Summary form only given. A number of metallic glasses that exhibit a wide supercooled liquid region before crystallization and a high glass-forming ability have been discovered. These metallic glasses exhibit useful properties such as high strength and high stiffness and can be fabricated from the melt in a bulk form with a thickness of {approx} 10 mm. The high glass-forming ability facilitates the formation of metallic glass powders by conventional gas-atomization technique. Subsequent consolidation of the powders to any dimensions is possible due to the viscous flow of the material in the supercooled liquid region. Hence, the synthesis of bulk metallic glasses using gas atomization coupled with subsequent consolidation holds a promising future. Atom probe tomography, X-ray diffraction and differential scanning calorimetry (DSC) characterizations of gas atomized powder particles of a Cu{sub 47}Ti{sub 33}Zr{sub 11}Ni{sub 8}Si{sub 1} metallic glass have been performed. The needle-shaped specimens required for the local electrode atom probe were fabricated from individual 10-40 mum diameter particles with the use of a dual beam focused ion beam miller. The microstructure of the alloy was investigated from the as-atomized powder and annealing treatments up to the completion of the first and second exothermic events at 785 and 838 K. Atom probe tomography revealed that the microstructure consisted of an interconnected network structure of two amorphous phases after an annealing treatment of 360 min. at 623 K. A fine-scale multiphase microstructure of an irregularly shaped copper-enriched and titanium-, nickel- and silicon-depleted phase that was 10-20 nm in extent, a higher number density of smaller, {approx}10 nm diameter, and roughly spherical titanium-enriched and copper- and zirconium-depleted phase and a matrix phase was found after continuous heating in a DSC to 785 and 838 K. The scanning electron microscope also revealed 4 distinct coarser phases consistent

  5. Quantum-Gas Microscope for Fermionic Atoms

    NASA Astrophysics Data System (ADS)

    Cheuk, Lawrence W.; Nichols, Matthew A.; Okan, Melih; Gersdorf, Thomas; Ramasesh, Vinay V.; Bakr, Waseem S.; Lompe, Thomas; Zwierlein, Martin W.

    2015-05-01

    We realize a quantum-gas microscope for fermionic 40K atoms trapped in an optical lattice, which allows one to probe strongly correlated fermions at the single-atom level. We combine 3D Raman sideband cooling with high-resolution optics to simultaneously cool and image individual atoms with single-lattice-site resolution at a detection fidelity above 95%. The imaging process leaves the atoms predominantly in the 3D motional ground state of their respective lattice sites, inviting the implementation of a Maxwell's demon to assemble low-entropy many-body states. Single-site-resolved imaging of fermions enables the direct observation of magnetic order, time-resolved measurements of the spread of particle correlations, and the detection of many-fermion entanglement.

  6. 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...

  7. 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...

  8. A Rapid, Low-Cost Method to Determine Travel Times at Managed Aquifer Recharge Operations Using Noble Gas Tracers

    NASA Astrophysics Data System (ADS)

    Moran, J. E.; Visser, A.; Singleton, M. J.; Esser, B. K.; Halliwell, M.; Hillegonds, D. J.

    2012-12-01

    Managed aquifer recharge is a key component for the sustainable use of surface water and groundwater in the arid western U.S. When recycled water is a recharge water source, subsurface residence time, required for bacteria and virus deactivation, is best verified by application of an extrinsic tracer. Desirable tracer properties include: no real or perceived health risk, inexpensive even for a large volume of tagged water, large dynamic range, efficient introduction, convenient sampling methods, and rapid, low-cost analysis. We have developed and tested a dissolved noble gas tracer technique ideally suited for tracing large water volumes at managed aquifer recharge facilities. In an application of the method at a water district's facilities in the San Francisco Bay area, Xenon was introduced into a 106 m3 pond over a period of 7 days using a 300 m length of gas-permeable silicone tubing. Samples from the pond, near-field shallow monitoring wells, and production wells about 400 m from the recharge pond were analyzed for dissolved Xe by noble gas membrane inlet mass spectrometry (NGMIMS). The NGMIMS uses a syringe pump, gas-permeable membrane inlet, and quadrupole residual gas analyzer for measurement of noble gas concentrations. Samples are collected in VOA vials, and analysis can be carried out in real-time, with a measurement uncertainty of about 5% for Xe. Tracer first appeared in a production well 136 days after starting the tracer introduction at 0.7% (C/C0) of the peak pond xenon concentration. The cost of the tracer is about US650/106 m3 water, and the NGMIMS was assembled with parts totaling approximately US50,000, making application of the tracer method feasible for most managed aquifer recharge projects. This project is part of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program.

  9. 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.

  10. 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.

  11. Noble gas adsorption in two-dimensional zeolites: a combined experimental and density functional theory study

    NASA Astrophysics Data System (ADS)

    Wang, Mengen; Zhong, Jianqiang; Boscoboinik, Jorge Anibal; Lu, Deyu

    Zeolites are important industrial catalysts with porous three-dimensional structures. The catalytically active sites are located inside the pores, thus rendering them inaccessible for surface science measurements. We synthesized a two-dimensional (2D) zeolite model system, consisting of an (alumino)silicate bilayer weakly bound to a Ru (0001) surface. The 2D zeolite is suitable for surface science studies; it allows a detailed characterization of the atomic structure of the active site and interrogation of the model system during the catalytic reaction. As an initial step, we use Ar adsorption to obtain a better understanding of the atomic structure of the 2D zeolite. In addition, atomic level studies of rare gas adsorption and separation by zeolite are important for its potential application in nuclear waste sequestration. Experimental studies found that Ar atoms can be trapped inside the 2D-zeolite, raising an interesting question on whether Ar atoms are trapped inside the hexagonal prism nano-cages or at the interface between the (alumino)silicate bilayer and Ru(0001), or both. DFT calculations using van der Waals density functionals were carried out to determine the preferred Ar adsorption sites and the corresponding adsorption energies. This research used resources of the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704.

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

    SciTech Connect

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

    2010-12-06

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

  13. Noble gases in pure lipid membranes.

    PubMed

    Sierra-Valdez, F J; Ruiz-Suárez, J C

    2013-03-21

    The mechanism of how a noble gas modifies the excitability of nerve cells and how such excitability can be recovered under hyperbaric pressure remains unclear. Here we present a calorimetric study where the melting point depression of pure lipid membranes induced by noble gases and its recovery with a hydrostatic pressure is addressed. A correlation is found between the electric polarizability (α) of these gases and their effect on the melting transition of the membranes. These results concur with other findings to support the idea that general anesthesia only depends on the ability of a certain atom or molecule to increase the general disorder of the membrane.

  14. Burnup determination and age dating of spent nuclear fuel using noble gas isotopic analysis

    SciTech Connect

    Charlton, W.S.; Perry, R.T.; Parish, T.A.; Hemberger, P.H.

    1999-07-01

    During the chopping and dissolving phases of reprocessing, gases (such as tritium, krypton, xenon, iodine, carbon dioxide, nitrogen oxide, and steam) are released. These gases are traditionally transferred to a gas-treatment system for treatment, release, and/or recycle. Because of their chemically inert nature, the xenon and krypton noble gases are generally released directly into the loser atmosphere through the facility's stack. These gases (being fission products) contain information about the fuel being reprocessed and may prove a valuable monitor of reprocessing activities. Two properties of the fuel that may prove valuable from a safeguards standpoint are the fuel burnup and the fuel age (or time since discharge from the reactor). Both can be used to aid in confirming declared activities, and the burnup is generally indicative of the usability of the fuel for fabricating nuclear explosives. A study has been ongoing at Los Alamos National Laboratory to develop a methodology to determine spent-fuel parameters from measured xenon and/or krypton isotopic ratios on-stack at reprocessing facilities. This study has resulted in the generation of the NOVA data analysis code, which links to a comprehensive database of reactor physics parameters (calculated using the Monteburns 3.01 code system). NOVA has been satisfactorily tested for burnup determination of weapons-grade fuel from a US production reactor. Less effort has been spent quantifying NOVA's ability to predict burnup and fuel age for power reactor fuel. The authors describe the results predicted by NOVA for xenon and krypton isotopic ratios measured after the dissolution of spent-fuel samples from the Borssele reactor. The Borssele reactor is a 450-MW(electric) pressurized water reactor (PWR) consisting of 15 x 15 KWU assemblies. The spent-fuel samples analyzed were single fuel rods removed from one assembly and dissolved at the La Hague reprocessing facility. The assembly average burnup was estimated at 32

  15. Quantum Gas Microscope for Fermionic Atoms

    NASA Astrophysics Data System (ADS)

    Okan, Melih; Cheuk, Lawrence; Nichols, Matthew; Lawrence, Katherine; Zhang, Hao; Zwierlein, Martin

    2016-05-01

    Strongly interacting fermions define the properties of complex matter throughout nature, from atomic nuclei and modern solid state materials to neutron stars. Ultracold atomic Fermi gases have emerged as a pristine platform for the study of many-fermion systems. In this poster we demonstrate the realization of a quantum gas microscope for fermionic 40 K atoms trapped in an optical lattice and the recent experiments which allows one to probe strongly correlated fermions at the single atom level. We combine 3D Raman sideband cooling with high- resolution optics to simultaneously cool and image individual atoms with single lattice site resolution at a detection fidelity above 95%. The imaging process leaves the atoms predominantly in the 3D motional ground state of their respective lattice sites, inviting the implementation of a Maxwell's demon to assemble low-entropy many-body states. Single-site resolved imaging of fermions enables the direct observation of magnetic order, time resolved measurements of the spread of particle correlations, and the detection of many-fermion entanglement. NSF, AFOSR-PECASE, AFOSR-MURI on Exotic Phases of Matter, ARO-MURI on Atomtronics, ONR, a Grant from the Army Research Office with funding from the DARPA OLE program, and the David and Lucile Packard Foundation.

  16. Absorption spectroscopy of xenon and ethylene-noble gas mixtures at high pressure: towards Bose-Einstein condensation of vacuum ultraviolet photons

    NASA Astrophysics Data System (ADS)

    Wahl, Christian; Brausemann, Rudolf; Schmitt, Julian; Vewinger, Frank; Christopoulos, Stavros; Weitz, Martin

    2016-12-01

    Bose-Einstein condensation is a phenomenon well known for material particles as cold atomic gases, and this concept has in recent years been extended to photons confined in microscopic optical cavities. Essential for the operation of such a photon condensate is a thermalization mechanism that conserves the average particle number, as in the visible spectral regime can be realized by subsequent absorption re-emission processes in dye molecules. Here we report on the status of an experimental effort aiming at the extension of the concept of Bose-Einstein condensation of photons towards the vacuum ultraviolet spectral regime, with gases at high-pressure conditions serving as a thermalization medium for the photon gas. We have recorded absorption spectra of xenon gas at up to 30 bar gas pressure of the 5p^6-5p^56s transition with a wavelength close to 147 nm. Moreover, spectra of ethylene noble gas mixtures between 158 and 180 nm wavelength are reported.

  17. WLS R&D for the detection of noble gas scintillation at LBL: seeing the light from neutrinos, to dark matter, to double beta decay

    NASA Astrophysics Data System (ADS)

    Gehman, V. M.

    2013-09-01

    Radiation detectors with noble gasses as the active medium are becoming increasingly common in experimental programs searching for physics beyond the standard model. Nearly all of these experiments rely to some degree on collecting scintillation light from noble gasses. The VUV wavelengths associated with noble gas scintillation mean that most of these experiments use a fluorescent material to shift the direct scintillation light into the visible or near UV band. We present an overview of the R&D program at LBL related to noble gas detectors for neutrino physics, double beta decay, and dark matter. This program ranges from precise measurements of the fluorescence behavior of wavelength shifting films, to the prototyping of large are VUV sensitive light guides for multi-kiloton detectors.

  18. A preliminary report on noble gas isotope analyses using the Helix-MC multi-collector mass spectrometer

    NASA Astrophysics Data System (ADS)

    Honda, M.; Zhang, X.; Phillips, D.; Szczepanski, S.; Deerberg, M.; Hamilton, D.; Krummen, M.; Schwieters, J.

    2013-12-01

    Analyses of noble gas isotopes by multi-collector mass spectrometry substantially improve measurement precision and accuracy, with the potential to revolutionise applications to cosmo-geo-sciences. The Helix-MC noble gas mass spectrometer manufactured by Thermo-Fisher is a 350mm, 120 degree extended geometry, high resolution, multi-collector mass spectrometer for the simultaneous analysis of noble gas isotopes. The detector array includes a fixed axial (Ax) detector, 2 adjustable high mass (H1 and H2) detectors and 2 adjustable low mass (L1 and L2) detectors. Each detector is equipped with a Faraday/ion counting multiplier CFM (Combined Faraday and CDD Multiplier) detector. Mass resolution and mass resolving power on the H2, Ax and L2 detectors of the Helix-MC installed at the Australian National University (ANU) are approximately 1,800 and 8,000, respectively. The noble gas handling system on-line to the Helix-MC consists of: (1) a resistively-heated, double-vacuum, tantalum furnace system, (2) air actuated vacuum crusher, (3) Photon-Machines diode laser heating system, (4) Janis He cryogenic trap assembly, (5) gas purification system and (6) standard gas pipette tanks, which are totally automated and controlled by the Qtegra software platform developed by Thermo-Fisher. Eleven repeat measurements of atmospheric Ar using the H2 Faraday (1E11 ohm resistor) and L2 CDD collectors on the Helix-MC, yield a mean 40Ar/36Ar ratio of 322.09 +- 0.28 (0.089%) with a 4,700 fA 40Ar beam current. This result compares favourably with the precision achieved by the Argus VI at the University of Melbourne (318.12 +- 0.17; 0.052%; n = 10) with a similar beam size of 4,200 fA. The high mass resolution of the L2 collector permits complete separation of the 36Ar and interfering 3 x 12C (required mass resolution (MR) of 1,100) and partial separation of H35Cl (MR = 3,900). This capability enables evaluation of the significance of Ar isotopic interferences related to the correction of

  19. In search of the noble gas 3.52 Ga atmospheric signatures

    NASA Astrophysics Data System (ADS)

    Pujol, M.; Marty, B.; Philippot, P.

    2008-12-01

    nuclear reactions on Xe isotope production, barite from 30m shallower depth in the same core were analyzed. Variable excesses can be linked to spallogenic and cosmogenic reactions ([4] [5] [6]) which allow the primitive Xe isotopic signature to be isolated from subsequent secondary production. Models of the archaean atmospheric noble gas signature can thereby be compared with different theories on primitive atmospheric composition. [1] Staudacher T. Allègre C.J. (1982) EPSL 60, p 389-406 [2] Van Kranendonk MJ., Hickman A.H., Williams I.R. and Nijman W. (2001) Rec.-Geol. Surv. West. Aust. 2001/9, 134 [3] Foriel J., Philippot P., Rey P., Somogyi A., Banks D. and Ménez B. (2004) EPSL, 228, 451-463 [4]Srinivasan B. (1976) EPSL, 31, 129-141 [5]Charalambus S. (1971) Nuclear Physics, A166, 145 [6]Meshik A. P., Hohenberg C. M., Pravdivtseva O. V. and Kapusta Y. (2001) Phys. Rev., C 64, 035205-1 035205-6

  20. Identifying the Sources of Methane in Shallow Groundwaters in Parker and Hood Counties, Texas through Noble Gas Signatures

    NASA Astrophysics Data System (ADS)

    Wen, T.; Castro, M. C.; Nicot, J. P.; Hall, C. M.; Mickler, P. J.; Darvari, R.

    2015-12-01

    With rising demands for cleaner domestic energy resources, horizontal drilling and hydraulic fracturing techniques in unconventional hydrocarbon exploration have been extensively developed. However, the observation that some water wells have showed elevated concentrations of dissolved methane and other light hydrocarbons has caused public concern regarding unconventional energy extraction. In this contribution, we present noble gas data of production shale gases from the Barnett and Strawn Formations, as well as nearby groundwater samples in south-central Texas. The Barnett Shale located in the Fort Worth Basin at an average depth of ~2300 m is one of the most prominent shale gas plays in the U.S. This DOE-sponsored study explores the potential of noble gases for fingerprinting shale gas and thus, for identifying the sources of gas in aquifers overlying the Barnett Shale, due either to natural hydrocarbon occurrences or potentially related to gas production from unconventional energy resources. A total of 35 groundwater samples were collected in Parker and Hood counties in areas where high amounts of methane (>10 mg/L) were detected in shallow groundwater. Two gas samples were also collected directly from groundwater wells where bubbling methane was present. Preliminary results show that He concentrations in water samples, in excess of up to three orders of magnitude higher than expected atmospheric values are directly correlated with methane concentrations. 3He/4He ratio values vary from 0.030 to 0.889 times the atmospheric ratio with the lowest, more pure radiogenic contributions being associated with highest methane levels. The presence of crustally-produced radiogenic 40Ar is also apparent in groundwater samples with 40Ar/36Ar ratios up to 316. A combined analysis of 40Ar/36Ar ratios from groundwater wells bubbling gas and that of shale gas suggests that the source of this methane is not the heavily exploited Barnett Shale, but rather, the Strawn Formation.

  1. Single-bubble sonoluminescence from noble gases.

    PubMed

    Yasui, K

    2001-03-01

    Single-bubble sonoluminescence (SBSL) from noble gases in water is studied theoretically in order to clarify the reason of the distinguished feature that the luminescence is strong for all noble gases, while the other systems of cavitation luminescence are greatly enhanced by the presence of the heavy noble gas(xenon). It is clarified that in spite of the larger thermal conductivity of lighter noble gases the maximum temperature in a SBSL bubble of lighter noble gases is higher due both to the segregation of water vapor and noble gas inside a SBSL bubble and the stronger acoustic drive of a SBSL bubble of lighter noble gases.

  2. Single-bubble sonoluminescence from noble gases

    NASA Astrophysics Data System (ADS)

    Yasui, Kyuichi

    2001-03-01

    Single-bubble sonoluminescence (SBSL) from noble gases in water is studied theoretically in order to clarify the reason of the distinguished feature that the luminescence is strong for all noble gases, while the other systems of cavitation luminescence are greatly enhanced by the presence of the heavy noble gas(xenon). It is clarified that in spite of the larger thermal conductivity of lighter noble gases the maximum temperature in a SBSL bubble of lighter noble gases is higher due both to the segregation of water vapor and noble gas inside a SBSL bubble and the stronger acoustic drive of a SBSL bubble of lighter noble gases.

  3. Noble gas isotope signals of mid-ocean ridge basalts and their implication for upper mantle structure

    NASA Astrophysics Data System (ADS)

    Stroncik, Nicole A.; Niedermann, Samuel

    2016-04-01

    The geochemical structure of the upper mantle in general and its noble gas isotopic structure in particular have been the subject of countless studies, as both provide important insights into mantle dynamic processes and are essential for the formulation of mantle geodynamic models. This contribution presents a noble gas study of basaltic glasses derived from the Mid-Atlantic-Ridge (MAR) between 4 and 12° S, an area well known for its high degree of lithophile isotope heterogeneity and exhibiting anomalous crustal thickness. The Sr, Nd, Pb and Hf isotopies along this segment of the MAR range from ultra-depleted (more than NMORB) to highly enriched, and different concepts have been proposed to explain the observed isotopic signatures. Here we show that the high degree of heterogeneity is not confined to the isotopes of the lithophile elements, but is also shown by the noble gas isotopes and noble gas interelement ratios, such as e.g. 3He/22NeM or 4He/40Ar*. 3He/4He, 21Ne/22Neextra and 40Ar/36Ar range from 7.3 to 9.3 RA, from 0.05 to 0.08, and from 346 to 37,400, respectively. Nevertheless, the majority of the Ne isotope data are clearly aligned along a single mixing line in the Ne-three-isotope diagram, represented by the equation 20Ne/22Ne=70.5 x 21Ne/22Ne + 7.782, with a slope distinctly different from that of the MORB line, indicating that the ultra-depleted material is characterised by a significantly more nucleogenic 21Ne/22Ne isotopy than the normal depleted mantle. We show, based on covariations between 3He/4He and 21Ne/22Neextra with 206Pb/204Pb and 178Hf/177Hf, that the ultra-depleted material erupted at this MAR segment was most likely produced by an ancient, deep melting event. This implies that isotopic heterogeneities in the upper mantle are not solely caused by the injection of enriched materials from deep-seated mantle plumes or by crustal recycling but may also be due to differences in the depth and degree of melting of upper mantle material within

  4. Knee structure in double ionization of noble atoms in circularly polarized laser fields

    NASA Astrophysics Data System (ADS)

    Chen, Xiang; Wu, Yan; Zhang, Jingtao

    2017-01-01

    Nonsequential double ionization is characterized by a knee structure in the plot of double-ionization probability versus laser intensity. In circularly polarized (CP) laser fields, this structure has only been observed for Mg atoms. By choosing laser fields according to a scaling law, we exhibit the knee structure in CP laser fields for Ar and He atoms. The collision of the ionized electron with the core enhances the ionization of the second electron and forms the knee structure. The electron recollision is universal in CP laser fields, but the ionization probability in the knee region decreases as the wavelength of the driven field increases. For experimental observations, it is beneficial to use target atoms with small ionization potentials and laser fields with short wavelengths.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  7. Groundwater noble gas, age, and temperature signatures in an Alpine watershed: Valuable tools in conceptual model development

    USGS Publications Warehouse

    Manning, A.H.; Caine, J.S.

    2007-01-01

    [1] Bedrock groundwater in alpine watersheds is poorly understood, mainly because of a scarcity of wells in alpine settings. Groundwater noble gas, age, and temperature data were collected from springs and wells with depths of 3-342 m in Handcart Gulch, an alpine watershed in Colorado. Temperature profiles indicate active groundwater circulation to a maximum depth (aquifer thickness) of about 200 m, or about 150 m below the water table. Dissolved noble gas data show unusually high excess air concentrations (>0.02 cm3 STP/g, ??Ne > 170%) in the bedrock, consistent with unusually large seasonal water table fluctuations (up to 50 m) observed in the upper part of the watershed. Apparent 3H/3He ages are positively correlated with sample depth and excess air concentrations. Integrated samples were collected from artesian bedrock wells near the trunk stream and are assumed to approximate flow-weighted samples reflecting bedrock aquifer mean residence times. Exponential mean ages for these integrated samples are remarkably consistent along the stream, four of five being from 8 to 11 years. The tracer data in combination with other hydrologic and geologic data support a relatively simple conceptual model of groundwater flow in the watershed in which (1) permeability is primarily a function of depth; (2) water table fluctuations increase with distance from the stream; and (3) recharge, aquifer thickness, and porosity are relatively uniform throughout the watershed in spite of the geological complexity of the Proterozoic crystalline rocks that underlie it. Copyright 2007 by the American Geophysical Union.

  8. 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.

  9. Noble Gas-Uranium Coordination and Intersystem Crossing for the CUO(Ne)x(Ng)n (Ng = Ar, Kr, Xe) Complexes in Solid Neon

    SciTech Connect

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

    2004-02-15

    Atomic uranium excited by laser ablation reacts with CO in excess neon to produce the novel CUO molecule, which forms weak complexes CUO(Ne)m with neon and stronger complexes CUO(Ne)x(Ng)n (Ng = Ar, Kr, Xe) when the heavier noble gas atoms are present. The heavier CUO(Ne)m-1(Ng) complexes are identified through the effects of CO isotopic and Ng substitution on the neon matrix infrared spectra and by comparison to DFT frequency calculations on model complexes CUO(Ng) (Ng = Ne, Ar, Kr, Xe). The U-C and U-O stretching frequencies of CUO(Ne)m-1(Ng) complexes are slightly red shifted from 1047 and 872 cm-1 frequencies for the 1Sigma+ CUO ground state neon complex, which identifies singlet ground state CUO(Ne)m-1(Ng) complexes in solid neon. The next singlet CUO(Ne)x(Ng)2 complexes in excess neon follow in like manner. However, stretching modes and the isotopic shifts of the higher CUO(Ne)x(Ng)n complex approach those of the pure argon matrix CUO(Ar)n complex, which characterizes triple t ground state complexes by comparison to DFT frequency calculations.

  10. Noble Gas Inventory of Micrometeorites Collected at the Transantarctic Mountains (TAM) and Indications for Their Provenance

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

    A variety of processes have been considered possibly contributing the volatiles including noble gases to the atmospheres of the terrestrial planets (e.g., [1-3]). Special consideration has been given to the concept of accretion of volatile-rich materials by the forming planets. This might include infalling planetesimals and dust, and could include material from the outer asteroid belt, as well as cometary material from the outer solar system. Currently, the dominant source of extraterrestrial material accreted by the Earth is represented by micrometeorites (MMs) with sizes mostly in the 100-300 micron range [3, 4]). Their role has been assessed by [3], who conclude that accretion of early micrometeorites played a major role in the formation of the terrestrial atmosphere and oceans. We have therefore set out to investigate in more detail the inventory of noble gases in MMs. Here we summarize some of our results obtained on MMs collected in micrometeorite traps of the Transantarctic Mountains [5].

  11. Noble Gas Tracing of Subsurface CO2 Origin and the Role of Groundwater as a CO2 Sink

    NASA Astrophysics Data System (ADS)

    Zhou, Z.; Ballentine, C. J.; Schoell, M.; Stevens, S. H.

    2003-12-01

    The source, generation, migration and accumulation of CO2 gas associated either alone or with hydrocarbons are unclear and therefore hard to predict. So far, noble gases provide one of the best tools to resolve this question, because they are conservative within the subsurface system. The atmosphere-derived noble gases dissolved in groundwater do not react with the rock system, while noble gases produced in the rock phase by radioactive decay or input from magmatic source are isotopically distinct and can be resolved from the dissolved air-derived noble gases. 10 samples were taken from a CO2-rich natural gas reservoir in Jackson Dome, Mississippi, USA to investigate its origin and extent of interaction with the groundwater system. The area lies within the Mississippi Interior Salt Basin. It is bounded on the north by the Pickens-Gilbertown fault system, the updip limit of the Jurassic Louann Salt unit, and on the south by basement highs of the Wiggins, South Mississippi, and Lasalle uplifts. We present compositional, stable isotope and noble gas results of Jackson Dome samples. Gas composition is 98.75-99.38% CO2, with small amounts of methane and nitrogen. CO2 content increases linearly with the decrease of CH4. d13C(CO2) in all samples ranges between -3.55 and -2.57 per mil, increasing with the increase of the CO2 content. Atmosphere-derived He contributions are negligible in all cases. 3He/4He ratios are between 4.27 and 5.01Ra, indicating a strong mantle signature. Crustal 4He in these samples therefore accounts for between 7.0% and 20.8%, the remainder being magmatic in origin. 40Ar/36Ar ratios are all above air ratio, ranging between 4071 and 6420. Air corrected 40Ar* vary between 92.7 and 95.4%, to give 4He/40Ar* ratios of between 1.26 and 2.52. This range is comparable with values estimated for the upper mantle. CO2/3He values are between 1.09E+9 and 4.62E+9, and also fall in the mantle range, indicating that the CO2 gas in Jackson Dome is also

  12. Noble gas paleotemperatures and water contents of stalagmites - a new extraction tool and a new paleoclimate proxy

    NASA Astrophysics Data System (ADS)

    Vogel, N.; Scheidegger, Y.; Brennwald, M. S.; Fleitmann, D.; Figura, S.; Wieler, R.; Kipfer, R.

    2012-04-01

    Stalagmites represent excellent multi-proxy paleoclimate archives as they cover long timescales and can be dated with high precision [e.g., 1]. The absolute temperature at which a stalagmite grew, can be deduced from the amounts of atmospheric noble gases dissolved in the stalagmite's fluid inclusion water (= noble gas temperature, NGT) [2-4]. We present technical advances towards more robust NGT determinations and also propose a new paleoclimate proxy, namely the stalagmite's water content, which is a "by-product" of NGT determination. Water contents and oxygen isotope records of two Holocene stalagmites from Socotra Island (Yemen) were found to vary systematically: progressively lighter oxygen is accompanied by decreasing water contents and vice versa. Via the oxygen isotope records [5] the stalagmites' water contents are linked to the amounts of precipitation on Socotra Island. High precipitation, i.e., high drip rates lead to homogeneous calcite growth with low porosity and therefore a small number of water-filled inclusions, i.e. low water contents. A reduction of drip water supply fosters irregular crystal growth with higher porosity, leading to higher water contents of the calcite (see also [6]). Therefore the stalagmites' water contents seem to record changes in drip water supply and, under favourable conditions, changes in regional precipitation. The current method to extract water and noble gases from stalagmite samples is experimentally challenging and subject to certain limitations (e.g., time-consuming sample preparation in a glove box, temperature restrictions for water extraction, and the often inadequate correction for air from residual air-filled inclusions [3, 4]). To overcome these limitations we have developed a new type of crusher directly attached to our noble gas line. It not only allows crushing and separating the samples into different grain size fractions in vacuo, but the separates can be individually heated to significantly higher

  13. Experimental Investigations of Halogen and Noble Gas Geochemistry as Constraints on Planetary Outgassing

    NASA Astrophysics Data System (ADS)

    Musselwhite, D. S.; Drake, M. J.; Swindle, T. D.

    1992-07-01

    Introduction The ^129Xe/^132Xe ratio in Mid-Ocean Ridge Basalts (MORBs) is higher than in the atmosphere and Ocean Island Basalts. Enhanced ^129Xe/^132Xe ratios are widely regarded to be the result of ^129I decay (t(sub)1/2 = 16 m.y.) early in solar system history (e.g. Swindle et al., 1986). Allegre et al. (1983, 1988) proposed a catastrophic degassing scheme to explain this excess. Both Musselwhite et al. (1990) and Hiyagon and Ozima (1990) have noted that because mineral/melt partition coefficients (D) for I appear lower than for Xe, the I/Xe ratio may not be enhanced in the mantle by mineral/melt fractionation. Musselwhite et al. (1990) proposed recycling of I back into the mantle following outgassing, and Hiyagon and Ozima (1990) proposed impact degassing of the mantle as a way around this problem. Knowledge of the relative values of D(I) and D(Xe) is important to the discussion of early planetary outgassing models. Although the dataset for D(I) values is not complete, the known values so far are uniformly low. The dataset for Xe on the other hand is quite ambiguous. Experimentally determined values for D(Xe) vary widely--ranging from 0.05 to >> 1 (Hiyagon and Ozima, 1986; Broadhurst et al., 1992), and it is unclear which of the values is the geologically significant one. Particularly important is the question of whether D(Xe) is greater than or less than unity. Partitioning Experiments: We have undertaken to simultaneously determine the D(I) and D(Ar) values directly, then calculate the D(Xe) from D(Ar). This approach is possible because experiments investigating the mineral/melt partitioning of noble gases, while not consistent in an absolute sense between experiments, do display a consistent trend with the lightest noble gases being most incompatible and Xe most compatible. We are adapting our technique to determine D(Kr) and D(Xe) directly. Finely crushed silica glass (~100 micrometer grain size) was placed in a gas pressure vessel. The vessel was

  14. Noble gases in crude oils from the Paris Basin, France: Implications for the origin of fluids and constraints on oil-water-gas interactions

    NASA Astrophysics Data System (ADS)

    Pinti, Daniele L.; Marty, Bernard

    1995-08-01

    In order to investigate the potential of noble gases to trace the dynamics of oil reservoirs, we have analysed the abundance and isotopic composition of all noble gases (He, Ne, Ar, Kr, and Xe) in crude oils from the Paris Basin, France, using a new extraction and purification procedure. The main oil reservoirs are presently located in the Jurassic (Dogger) limestone and in the Triassic (Keuper) sandstone, but hydrocarbons originated from a common source rock formation located in the interbedded Liassic sequence. Despite this common origin, the abundance and isotopic ratios of the noble gases differ between the Dogger and the Keuper. The isotopic compositions of Kr and Xe are indistinguishable from that of air. 3He/ 4He ratios, higher than those predicted from radiogenic production in the sediments or in the crust, are attributed to the occurrence of mantle-derived 3He in the basin. Each sedimentary sequence is characterised by well defined and homogeneous 21Ne/ 22Ne and 40Ar/ 36Ar ratios, which average 0.0306 ± 0.0008 and 312 ± 10 for the Dogger and 0.0367 ± 0.0012 and 664 ± 30 for the Keuper, respectively. The main source of radiogenic noble gases appears to be the continental crust underlying the basin, with possible regional contributions of noble gas isotopes produced in the sediments. The helium and argon isotopic ratios of the Dogger oils are very similar to those observed in geothermal waters flowing in the Dogger aquifer throughout the basin, demonstrating that noble gases in oils derive from associated groundwaters. Oil reservoirs in the Paris Basin therefore accumulate noble gases from wide regions of the continental crust through cross-formational flow of groundwaters and subsequent partitioning into oil. This observation implies that noble gases cannot be directly used to date oils, but can provide time constraints if (1) water/oil interactions are quantified and (2) the residence time as well as the noble gas characteristics of associated

  15. The Scattering of Gas Atoms from Solid Surfaces

    ERIC Educational Resources Information Center

    Walton, Alan J.

    1977-01-01

    Traditional undergraduate courses in gas kinetic theory encourage the view that in all collisions between a gas atom and a surface, the angle of incidence of the gas atom equals its angle of reflection. This article illustrates and explains the incorrectness in assuming specular reflection and zero dwell time. (Author/MA)

  16. The Scattering of Gas Atoms from Solid Surfaces

    ERIC Educational Resources Information Center

    Walton, Alan J.

    1977-01-01

    Traditional undergraduate courses in gas kinetic theory encourage the view that in all collisions between a gas atom and a surface, the angle of incidence of the gas atom equals its angle of reflection. This article illustrates and explains the incorrectness in assuming specular reflection and zero dwell time. (Author/MA)

  17. Noble gas composition and 40Ar/39Ar age in eclogites from the main hole of the Chinese Continental Scientific Drilling project

    NASA Astrophysics Data System (ADS)

    Hopp, Jens; Schwarz, Winfried H.; Trieloff, Mario; Meyer, Hans-Peter; Hanel, Michael; Altherr, Rainer

    2016-10-01

    We present the first comprehensive noble gas study on eclogites. The four eclogite samples were recovered during the Chinese Continental Scientific Drilling and are from two distinct profile depth sections differing in their degree of interaction with meteoric water, based on their δ 18O-values (surface related and of mantle-type). Hence, noble gas analyses offer the potential to further discriminate between shallow (meteoric) and deep (mantle) fluid sources. Noble gas compositions reveal typical crustal fluid compositions, characterized by a variable mixture of atmospheric gases with significant contributions of nucleogenic neon, radiogenic 4He*, radiogenic 40Ar*, fissiogenic 131-136Xe, and presumably bariogenic 131Xe, but no significant addition of mantle gases. This signature can be also considered to represent one endmember component of eclogitic diamonds. Concentrations of non-radiogenic noble gases are rather low, with depletion of light relative to the heavier noble gases. Eclogites from lower depth which experienced a higher degree of interaction with meteoric water also showed higher contributions of atmospheric gas compared with eclogites recovered from greater depth. This is interpreted to result from interaction with high-salinity fluids during ultrahigh pressure (UH P). It demonstrates that the atmospheric noble gas abundance is a proxy for interaction with surface related fluids. 40Ar/39Ar (inverse) isochron ages of two phengite separates (241.2 ± 0.4 Ma and 275.0 ± 1.8 Ma, 1 σ-errors) predate the main phase of UH P metamorphism (ca. 220 Ma). Biotite yields an integrated age of about 1100 Ma. These age values are interpreted to reflect the likely addition of excess 40Ar without any chronological meaning.

  18. Highly ionized atoms in cooling gas

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  19. Powder Size and Distribution in Ultrasonic Gas Atomization

    NASA Astrophysics Data System (ADS)

    Rai, G.; Lavernia, E.; Grant, N. J.

    1985-08-01

    Ultrasonic gas atomization (USGA) produces powder sizes dependent on the ratio of the nozzle jet diameter to the distance of spread dt/R, Powder size distribution is attributed to the spread of atomizing gas jets during travel from the nozzle exit to the metal stream. The spread diminishes at higher gas atomization pressures. In this paper, calculated powder sizes and distribution are compared with experimentally determined values.

  20. Modeling nuclear and electronic recoils in noble gas detectors with NEST

    NASA Astrophysics Data System (ADS)

    Mock, Jeremy; NEST Collaboration

    2015-10-01

    Noble gases such as xenon and argon are used as targets in single and dual phased rare event detectors like those used in the search for dark matter. Such experiments require an understanding of the behavior of the target material in the presence of low-energy ionizing radiation. This understanding allows an exploration of detector effects such as threshold, energy and position reconstruction, and pulse shape discrimination. The Noble Element Simulation Technique (NEST) package is a comprehensive code base that models the scintillation and ionization yields from liquid and gaseous xenon and argon in the energy regimes of interest to many types of experiments, like dark matter and neutrino detectors. NEST is built on multiple physics models, which are constrained by available data for both electronic and nuclear recoils. A substantial body of data exists in the literature, and we are reaching an era in which sub-keV yields can be explored experimentally. Here we present a new global analysis of all available nuclear recoil data, and the latest updates to the electronic recoil model, in light of recent low-energy measurements and an improved understanding of detector systematics.

  1. A Concept for a Low Pressure Noble Gas Fill Intervention in the IFE Fusion Test Facility (FTF) Target Chamber

    SciTech Connect

    Gentile, C. A.; Blanchard, W. R.; Kozub, T. A.; Aristova, M.; McGahan, C.; Natta, S.; Pagdon, K.; Zelenty, J.

    2010-01-14

    An engineering evaluation has been initiated to investigate conceptual engineering methods for implementing a viable gas shield strategy in the Fusion Test Facility (FTF) target chamber. The employment of a low pressure noble gas in the target chamber to thermalize energetic helium ions prior to interaction with the wall could dramatically increase the useful life of the first wall in the FTF reactor1. For the purpose of providing flexibility, two target chamber configurations are addressed: a five meter radius sphere and a ten meter radius sphere. Experimental studies at Nike have indicated that a low pressure, ambient gas resident in the target chamber during laser pulsing does not appear to impair the ability of laser light from illuminating targets2. In addition, current investigations into delivering, maintaining, and processing low pressure gas appear to be viable with slight modification to current pumping and plasma exhaust processing technologies3,4. Employment of a gas fill solution for protecting the dry wall target chamber in the FTF may reduce, or possibly eliminate the need for other attenuating technologies designed for keeping He ions from implanting in first wall structures and components. The gas fill concept appears to provide an effective means of extending the life of the first wall while employing mostly commercial off the shelf (COTS) technologies. Although a gas fill configuration may provide a methodology for attenuating damage inflicted on chamber surfaces, issues associated with target injection need to be further analyzed to ensure that the gas fill concept is viable in the integrated FTF design5. In the proposed system, the ambient noble gas is heated via the energetic helium ions produced by target detonation. The gas is subsequently cooled by the chamber wall to approximately 800oC, removed from the chamber, and processed by the chamber gas processing system (CGPS). In an optimized scenario of the above stated concept, the chamber

  2. Determining CO2 storage potential during miscible CO2 enhanced oil recovery: Noble gas and stable isotope tracers

    USGS Publications Warehouse

    Shelton, Jenna L.; McIntosh, Jennifer C.; Hunt, Andrew; Beebe, Thomas L; Parker, Andrew D; Warwick, Peter D.; Drake, Ronald; McCray, John E.

    2016-01-01

    Rising atmospheric carbon dioxide (CO2) concentrations are fueling anthropogenic climate change. Geologic sequestration of anthropogenic CO2 in depleted oil reservoirs is one option for reducing CO2 emissions to the atmosphere while enhancing oil recovery. In order to evaluate the feasibility of using enhanced oil recovery (EOR) sites in the United States for permanent CO2 storage, an active multi-stage miscible CO2flooding project in the Permian Basin (North Ward Estes Field, near Wickett, Texas) was investigated. In addition, two major natural CO2 reservoirs in the southeastern Paradox Basin (McElmo Dome and Doe Canyon) were also investigated as they provide CO2 for EOR operations in the Permian Basin. Produced gas and water were collected from three different CO2 flooding phases (with different start dates) within the North Ward Estes Field to evaluate possible CO2 storage mechanisms and amounts of total CO2retention. McElmo Dome and Doe Canyon were sampled for produced gas to determine the noble gas and stable isotope signature of the original injected EOR gas and to confirm the source of this naturally-occurring CO2. As expected, the natural CO2produced from McElmo Dome and Doe Canyon is a mix of mantle and crustal sources. When comparing CO2 injection and production rates for the CO2 floods in the North Ward Estes Field, it appears that CO2 retention in the reservoir decreased over the course of the three injections, retaining 39%, 49% and 61% of the injected CO2 for the 2008, 2010, and 2013 projects, respectively, characteristic of maturing CO2 miscible flood projects. Noble gas isotopic composition of the injected and produced gas for the flood projects suggest no active fractionation, while δ13CCO2 values suggest no active CO2dissolution into formation water, or mineralization. CO2 volumes capable of dissolving in residual formation fluids were also estimated along with the potential to store pure-phase supercritical CO2. Using a combination

  3. Plasma and laser kinetics and field emission from carbon nanotube fibers for an Advanced Noble Gas Laser (ANGL)

    NASA Astrophysics Data System (ADS)

    Moran, Paul J.; Lockwood, Nathaniel P.; Lange, Matthew A.; Hostutler, David A.; Guild, Eric M.; Guy, Matthew R.; McCord, John E.; Pitz, Greg A.

    2016-03-01

    A metastable argon laser operating at 912 nm has been demonstrated by optically pumping with a pulsed titanium sapphire laser to investigate the temporal dynamics of an Advanced Noble Gas Laser (ANGL). Metastable argon concentrations on the order of 1011 cm-3 were maintained with the use of a radio frequency (RF) capacitively coupled discharge. The end-pumped laser produced output powers under 2 mW of average power with pulse lengths on the order of 100 ns. A comparison between empirical results and a four level laser model using longitudinally average pump and inter-cavity intensities is made. An alternative, highly-efficient method of argon metastable production for ANGL was explored using carbon nanotube (CNT) fibers.

  4. Theoretical prediction of noble gas inserted halocarbenes: FNgCX (Ng = Kr, and Xe; X = F, Cl, Br, and I)

    NASA Astrophysics Data System (ADS)

    Chopra, Pragya; Ghosh, Ayan; Roy, Banasri; Ghanty, Tapan K.

    2017-09-01

    A new series of neutral noble gas inserted compounds involving halocarbenes, mainly, FNgCX (Ng = Kr, and Xe; X = F, Cl, Br, and I) has been predicted through various ab initio quantum chemical techniques such as MP2, DFT, CCSD(T) and MRCI. The structure, stabilities, charge distribution, harmonic vibrational frequencies and topological properties of these compounds have been investigated. It is found that the predicted species are energetically stable with respect to all the plausible 2-body and 3-body dissociation pathways, with the exception of the 2-body channel that leads to the global minimum products (FCX + Ng). Despite this, existence of finite barrier heights indicates that these compounds are kinetically stable with respect to global minimum products. The computational results indicate that it might be possible to prepare and characterize the most stable singlet state of FNgCX molecules under cryogenic conditions through suitable experimental technique(s).

  5. 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.

  6. Effect of hydration on the organo-noble gas molecule HKrCCH: role of krypton in the stabilization of hydrated HKrCCH complexes.

    PubMed

    Biswas, Biswajit; Singh, Prashant Chandra

    2015-11-11

    The effect of hydration on the fluorine free organo-noble gas compound HKrCCH and the role of krypton in the stabilization of the hydrated HKrCCH complexes have been investigated using the quantum chemical calculations on the HKrCCH-(H2O)n=1-6 clusters. Structure and energetics calculations show that water stabilizes HKrCCH through the π hydrogen bond in which the OH group of water interacts with the C[triple bond, length as m-dash]C group of HKrCCH. A maximum of four water molecules can directly interact with the C[triple bond, length as m-dash]C of HKrCCH and after that only inter-hydrogen bonding takes place between the water molecules indicating that the primary hydration shell contains four water molecules. Atom in molecule analysis depicts that π hydrogen bonded complexes of the hydrated HKrCCH are cyclic structures in which the OKr interaction cooperates in the formation of strong O-HC[triple bond, length as m-dash]C interaction. Structure, energetics and charge analysis clearly established that krypton plays an important role in the stabilization as well as the formation of the primary hydration shell of hydrated HKrCCH complexes.

  7. A coupled-cluster study on the noble gas binding ability of metal cyanides versus metal halides (metal = Cu, Ag, Au).

    PubMed

    Pan, Sudip; Gupta, Ashutosh; Saha, Ranajit; Merino, Gabriel; Chattaraj, Pratim K

    2015-11-05

    A coupled-cluster study is carried out to investigate the efficacy of metal(I) cyanide (MCN; M = Cu, Ag, Au) compounds to bind with noble gas (Ng) atoms. The M-Ng bond dissociation energy, enthalpy change, and Gibbs free energy change for the dissociation processes producing Ng and MCN are computed to assess the stability of NgMCN compounds. The Ng binding ability of MCN is then compared with the experimentally detected NgMX (X = F, Cl, Br) compounds. While CuCN and AgCN have larger Ng binding ability than those of MCl and MBr (M = Cu, Ag), AuCN shows larger efficacy toward bond formation with Ng than that of AuBr. Natural bond orbital analysis, energy decomposition analysis in conjunction with the natural orbital for chemical valence theory, and the topological analysis of the electron density are performed to understand the nature of interaction occurring in between Ng and MCN. The Ng-M bonds in NgMCN are found comprise an almost equal contribution from covalent and electrostatic types of interactions. The different electron density descriptors also reveal the partial covalent character in the concerned bonds.

  8. Evaluating the accretion of meteoritic debris and interplanetary dust particles in the GPC-3 sediment core using noble gas and mineralogical tracers

    NASA Astrophysics Data System (ADS)

    Darrah, Thomas H.; Poreda, Robert J.

    2012-05-01

    Extraterrestrial (ET) noble gases (helium and neon) in 35 sediment samples from Central Pacific core LL-44 GPC-3 demonstrate the variable flux of interplanetary dust particles (IDPs) and major meteorite impacts over the past 70 Ma (21-72 Ma). Spinel mineralogical and chemical compositions clearly distinguish major impact events from the continuous flux of IDPs, including the well-established Cretaceous/Tertiary (K/T) and late Eocene (E/O) impact boundaries. No spinel grains with chemical or mineralogical evidence of a distinctly ET origin were found in an extensive survey of 'background' samples (i.e. non E/O or K/T boundary) suggesting that either the carrier grains for ET noble gas occur within the Fe-Ti oxide mineral fraction observed in this study (found to include ilmenite and ulvospinel) or are too small for identification by SEM. The presence of ilmenite and ulvospinel suggest lunar regolith is a potential source for ET noble gas-rich particles. Noble gas analysis on both the EMF (extractable magnetic fraction) and the Bulk minus EMF (Bulk - EMF) show that the He and Ne compositions are consistent with partially degassed noble gas signatures of zero-age magnetic grains (Z-MAG) and stratospheric interplanetary dust particles (IDPs). Conclusive evidence for a 'planetary' (Ne-A) noble gas signature is found only in the bulk sediments at the K/T boundary, although all GPC-3 K/T fractions (Bulk, EMF, and HF Digestion) plot along a mixing line between planetary (Ne-A) and solar wind (SW). Spinels from major impact boundaries (K/T; E/O) exhibit dendritic texture and elevated [Ni], consistent with previous reports. In contrast to the otherwise consistent [3He] signal from IDPs, the [3He] at the known impact boundaries (K/T and E/O) actually decreases. These anomalously low [3He] are accompanied by significantly elevated [Ne] and significantly lower (3He/20Ne)solar ratios (˜10× lower) produced by both preferentially degassing of He relative to Ne at times of

  9. [Development of microwave plasma atomic emission detectors for gas chromatography].

    PubMed

    Yuan, Mao; Shi, Yuhua; Yu, Aimin; Zhang, Hanqi; Jin, Qinhan

    2007-05-01

    Three microwave plasmas including microwave induced plasma, capacitively coupled microwave plasma and microwave plasma torch as atomic emission detectors for gas chromatography are evaluated in their history, application and restriction, separately. The development of microwave plasma atomic emission detectors for gas chromatography is prospected.

  10. Ore genesis constraints on the Idaho Cobalt Belt from fluid inclusion gas, noble gas isotope, and ion ratio analyses

    USGS Publications Warehouse

    Hofstra, Albert H.; Landis, Gary P.

    2012-01-01

    The Idaho cobalt belt is a 60-km-long alignment of deposits composed of cobaltite, Co pyrite, chalcopyrite, and gold with anomalous Nb, Y, Be, and rare-earth elements (REEs) in a quartz-biotite-tourmaline gangue hosted in Mesoproterozoic metasedimentary rocks of the Lemhi Group. It is the largest cobalt resource in the United States with historic production from the Blackbird Mine. All of the deposits were deformed and metamorphosed to upper greenschist-lower amphibolite grade in the Cretaceous. They occur near a 1377 Ma anorogenic bimodal plutonic complex. The enhanced solubility of Fe, Co, Cu, and Au as chloride complexes together with gangue biotite rich in Fe and Cl and gangue quartz containing hypersaline inclusions allows that hot saline fluids were involved. The isotopes of B in gangue tourmaline are suggestive of a marine source, whereas those of Pb in ore suggest a U ± Th-enriched source. The ore and gangue minerals in this belt may have trapped components in fluid inclusions that are distinct from those in post-ore minerals and metamorphic minerals. Such components can potentially be identified and distinguished by their relative abundances in contrasting samples. Therefore, we obtained samples of Co and Cu sulfides, gangue quartz, biotite, and tourmaline and post-ore quartz veins as well as Cretaceous metamorphic garnet and determined the gas, noble gas isotope, and ion ratios of fluid inclusion extracts by mass spectrometry and ion chromatography. The most abundant gases present in extracts from each sample type are biased toward the gas-rich population of inclusions trapped during maximum burial and metamorphism. All have CO2/CH4 and N2/Ar ratios of evolved crustal fluids, and many yield a range of H2-CH4-CO2-H2S equilibration temperatures consistent with the metamorphic grade. Cretaceous garnet and post-ore minerals have high RH and RS values suggestive of reduced sulfidic conditions. Most extracts have anomalous 4He produced by decay of U and Th and

  11. Coherent Atom Optics with fast metastable rare gas atoms

    SciTech Connect

    Grucker, J.; Baudon, J.; Karam, J.-C.; Perales, F.; Vassilev, G.; Ducloy, M.; Bocvarski, V.

    2006-12-01

    Coherent atom optics experiments making use of an ultra-narrow beam of fast metastable atoms generated by metastability exchange are reported. The transverse coherence of the beam (coherence radius of 1.7 {mu}m for He*, 1.2 {mu}m for Ne*, 0.87 {mu}m for Ar*) is demonstrated via the atomic diffraction by a non-magnetic 2{mu}m-period reflection grating. The combination of the non-scalar van der Waals (vdW) interaction with the Zeeman interaction generated by a static magnetic field gives rise to ''vdW-Zeeman'' transitions among Zeeman sub-levels. Exo-energetic transitions of this type are observed with Ne*(3P2) atoms traversing a copper micro-slit grating. They can be used as a tunable beam splitter in an inelastic Fresnel bi-prism atom interferometer.

  12. Conceptual Engineering Method for Attenuating He Ion Interactions on First Wall Components in the Fusion Test Facility (FTF) Employing a Low-Pressure Noble Gas

    SciTech Connect

    C.A.Gentile, W.R.Blanchard, T.Kozub, C.Priniski, I.Zatz, S.Obenschain

    2009-09-21

    It has been shown that post detonation energetic helium ions can drastically reduce the useful life of the (dry) first wall of an IFE reactor due to the accumulation of implanted helium. For the purpose of attenuating energetic helium ions from interacting with first wall components in the Fusion Test Facility (FTF) target chamber, several concepts have been advanced. These include magnetic intervention (MI), deployment of a dynamically moving first wall, use of a sacrificial shroud, designing the target chamber large enough to mitigate the damage caused by He ions on the target chamber wall, and the use of a low pressure noble gas resident in the target chamber during pulse power operations. It is proposed that employing a low-pressure (~ 1 torr equivalent) noble gas in the target chamber will thermalize energetic helium ions prior to interaction with the wall. The principle benefit of this concept is the simplicity of the design and the utilization of (modified) existing technologies for pumping and processing the noble ambient gas. Although the gas load in the system would be increased over other proposed methods, the use of a "gas shield" may provide a cost effective method of greatly extending the first wall of the target chamber. An engineering study has been initiated to investigate conceptual engineering metmethods for implementing a viable gas shield strategy in the FTF.

  13. Magma dynamics at mid-ocean ridges by noble gas kinetic fractionation: Assessment of magmatic ascent rates

    NASA Astrophysics Data System (ADS)

    Paonita, A.; Martelli, M.

    2006-01-01

    Despite its impact in understanding oceanic crust formation and eruptive styles of related volcanism, magma dynamics at mid-ocean ridges are poorly known. Here, we propose a new method to assess ascent rates of mid-ocean ridge basalt (MORB) magmas, as well as their pre- and sin-eruptive dynamics. It is based on the idea that a rising magma can reach a variable degree of both CO2 supersaturation in melt and kinetic fractionation among noble gases in vesicles in relation to its ascent rate through the crust. To quantify the relationship, we have used a model of multicomponent bubble growth in MORB melts, developed by extending the single-component model of Proussevitch and Sahagian [A.A. Proussevitch, D.L. Sahagian, Dynamics and energetics of bubble growth in magmas: analytical formulation and numerical modeling, J. Geophys. Res. 103 (1998), 18223-18251.] to CO2-He-Ar gas mixtures. After proper parameterization, we have applied it to published suites of data having the required features (glasses from Pito Seamount and mid-Atlantic ridges). Our results highlight that the investigated MORB magmas display very different ranges of ascent rates: slow rises of popping rock forming-magmas that cross the crust (0.01-0.5 m/s), slightly faster rates of energetic effusions (0.1-1 m/s), up to rates of 1-10 m/s which fall on the edge between lava effusion and Hawaiian activity. Inside a single plumbing system, very dissimilar magma dynamics highlight the large differences in compressive stress of the oceanic crust on a small scale. Constraints on how the systems of ridges work, as well as the characteristics of the magmatic source, can also be obtained. Our model shows how measurements of both the dissolved gas concentration in melt and the volatile composition of vesicles in the same sample are crucial in recognizing the kinetic effects and definitively assessing magma dynamics. An effort should be made to correctly set the studied samples in the sequence of volcanic submarine

  14. Recycle and fractionation of U and K in the mantle via slab subduction; noble gas isotopic evidence from Polynesian HIMU

    NASA Astrophysics Data System (ADS)

    Hanyu, Takeshi; Tatsumi, Yoshiyuki; Kimura, Jun-Ichi

    2013-04-01

    The abundance and distribution of U and K in the Earth are critical not only for isotope and noble gas geochemistry but also for internal heat production in the mantle. While the concentration of U in bulk silicate Earth (BSE) has been estimated from the chondritic value, K concentration in BSE is poorly constrained. K concentration in BSE has been estimated using U concentration in BSE multiplied by the canonical K/U ratio (13000) on the ground that crustal and mantle-derived rocks show uniform K/U. However, such theory might be uncertain if the subducted slab had fractionated K/U and it remained isolated as a hidden reservoir. We present He-Ne-Ar isotopic compositions for Polynesian HIMU lavas with radiogenic Pb isotopic compositions. It has been widely accepted that the HIMU lavas are sourced from subducted ancient oceanic crust. K/U of the HIMU reservoir is constrained using the relative abundances of radiogenic and nucleogenic noble gases, because 40Ar/36Ar evolves by decay of 40K while production of 4He and 21Ne is related with U and Th decay. In 4He/40Ar*-4He/21Ne* space (asterisks denote radiogenic component), the HIMU lavas define a trend that is parallel to, but offset from the trend previously observed for other ocean island basalts. Using 4He/21Ne* as a monitor of elemental fractionation of noble gasses, fractionation-corrected 4He/40Ar* is higher than that expected for the mantle with the canonical K/U of 13000. K/U of the HIMU reservoir converted from 4He/40Ar* is approximately 3000. Low K/U of the HIMU reservoir is best explained by a model where this reservoir originates from subducted oceanic crust that preferentially lost K relative to U via dehydration during its subduction. Since the HIMU reservoir, involving subducted oceanic crust, is enriched in U, but not in K, previous estimates of K/U and K concentrations for BSE, that did not take this reservoir into consideration, will be too high. The mass balance calculation, considering continental

  15. Heterogeneous upper mantle Ne, Ar and Xe isotopic compositions and a possible Dupal noble gas signature recorded in basalts from the Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Parai, R.; Mukhopadhyay, S.; Standish, J. J.

    2012-12-01

    Variations in heavy noble gas (Ne, Ar, Xe) isotopic compositions provide unique insights into the nature of heterogeneities in the mantle. However, few precise constraints on mantle source heavy noble gas isotopic compositions are available due to ubiquitous shallow-level atmospheric contamination. As a result, the extent of heterogeneity in mid-ocean ridge basalt (MORB) mantle source Ne, Ar and Xe isotopic compositions is unknown. Basalts from the ultra-slow spreading Southwest Indian Ridge (SWIR) between 7°E and 25°E exhibit remarkable variability in He isotopic composition: SWIR 4He/3He spans half the total range observed in all mantle-derived basalts. Therefore, basalts from the SWIR provide a unique window into upper mantle heterogeneity and present an ideal opportunity to characterize variations in upper mantle heavy noble gas isotopic composition. Here we present new high-precision Ne, Ar and Xe isotopic compositions as well as He, CO2, Ne, Ar and Xe abundances measured in basalt glasses from the SWIR. After correcting the measured values for shallow-level atmospheric contamination, significant and systematic variations in mantle source Ne, Ar and Xe compositions are observed. We note that large variations in source 40Ar/36Ar and 129Xe/130Xe are observed in basalts removed from the influence of known hotspots, indicating a heterogeneous mid-ocean ridge basalt source. Thus, SWIR heavy noble gas data reveal a greater degree of source heterogeneity than is evident in the 4He/3He systematics alone. The observed heavy noble gas isotopic heterogeneities imply that the average MORB source 40Ar/36Ar and 129Xe/130Xe ratios are not yet well-determined. Variation in MORB source 40Ar/36Ar and 129Xe/130Xe at a given 4He/3He and 21Ne/22Ne may reflect heterogeneous recycling of atmospheric Ar and Xe. In particular, we find low mantle source 40Ar/36Ar and 129Xe/130Xe ratios in the eastern region of the study area, which may reflect the noble gas signature of the Dupal

  16. Noble gas component organization in Apollo 14 breccia 14318: /sup 129/I and /sup 244/Pu regolith chronology

    SciTech Connect

    Swindle, T.D.; Caffee, M.W.; Hohenberg, C.M.; Hudson, G.B.; Laul, J.C.; Simon, S.B.; Papike, J.J.

    1985-02-15

    Noble gas, petrological, and chemical studies made on grain-size separates from lunar regolith breccia 14318 demonstrate that the noble gases are organized into two functional components, volume-correlated and surface-correlated. As in regolith breccia 14301, volume-correlated xenon in 14318 is primarily spallation-derived and the surface-correlated component contains not only solar wind xenon but also significant amounts of ''parentless' xenon from the fission of now extinct /sup 244/Pu and the decay of now extinct /sup 129/I (''parentless'' means the daughter products were incorporated onto grain surfaces following decay of the parent nuclide elsewhere). The ratio of /sup 129/Xe//sup 136/Xe in the total surface-correlated parentless component, as identified in grain-size analysis, is substantially higher than in the least tightly bound parentless component identified in stepwise heating analyses, confirming the trend seen in 14301. If the order of release of gases in stepwise heating is related to the order of incorporation in the simplest way (first in, last out), incorporation of these grain-surface components was probably time-ordered. The /sup 129/Xe//sup 136/Xe ratio in each identifiable parentless component would then be characteristic of the xenon available for surface adsorption at the particular time of acquisition. Continuous variations in this ratio further suggest that incorporation of the parentless xenon was closely coupled with production. Such observations provide the basis for a new chronometer from which we conclude that acquisition of parentless xenon was an ongoing process spanning at least 90 m.y., beginning no more than 44 +- 34 m.y. after the formation of the most meteorites and possibly predating xenon acquisition for the earth.

  17. 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.

  18. Hydrochemistry and origin of CO2 gas and noble gas of carbonated mineral water in the Gyeongbuk-Gangwon Province, South Korea

    NASA Astrophysics Data System (ADS)

    Jeong, C. H.; Yoo, S. W.

    2012-04-01

    Hydrochemical, carbon isotopic (δ13CDIC) analyses of 11 samples, and noble gas isotopic analyses of 8 samples collected in the Gangwon and the Gyeongbuk area of South Korea were carried out to elucidate hydrochemical characteristics and to interpret the source of noble gases and CO2 gas. The carbonated mineral waters show a weak acidic pH between 5.59 and 6.04. An electrical conductivity of carbonated mineral waters ranges from 302 to 864 μS/cm. The chemical composition of all carbonated mineral waters can be grouped into only one type such as Ca-HCO3. A high content of Fe and Mn in carbonated mineral waters exceeds a regulation limit of drinking water. The δ13CDIC values of carbonated mineral waters show the range of -5.30~-2.84 ‰. This range indicates that the carbon of carbonated mineral waters is mainly supplied from a deep-seated source and partly from an inorganic carbonate source. The 3He/4He ratios of the carbonated mineral waters show the range of 1.51×10-6 to 6.45×10-6. The carbonated mineral waters on the 3He/4He and 4He/20Ne diagram are plotted into three groups: deep seated area such as mantle source, atmospheric area, and air-mantle mixing area. A wide range of 4He/20Ne ratios is observed (0.036×10-6 to 1.76×10-6), showing evidence that while radiogenic 4He is dominant in these water samples, He of mantle-origin is also supplied to these waters. It is estimated that supply of CO2 gas and noble gas of a deep-seated source into carbonated waters is closely related to geologic structures such as fault and geologic boundary. Key words: carbonated mineral waters, hydrochemical composition, carbon isotope, 3He/4He, deep-seated origin

  19. Where do noble gases hide in space?

    NASA Astrophysics Data System (ADS)

    Pauzat, F.; Ellinger, Y.

    Observations showing anomalous amounts of noble gas, especially in planetary atmospheres, are at the origin of a series of controversial interpretations from 1990 to nowadays (Hersant et al. (2004)). If, in a first step, we adopt a chemical point of view, we have to consider the possibility of associations of such elements (though usually considered as non reactive), with other molecules or atoms. Such complexes could trap the noble gases in some astrophysical objects at one time of their evolution, for example, in the early step of formation of protoplanetary disks. But two questions have to be answered to assert this type of hypothesis: which stable compounds could exist taking into account the environnement and which reactions could lead to such compounds? Hydrogen being by far the most abundant element in space, and neutral systems whose cohesion is driven by weak Van der Waals forces being unable to resist turbulence in space, the first and simplest association to consider is the one between the noble gas and the H3+ ion. Thus, DFT in the B3LYP, PW91 and BHandHLYP formalisms together with ab-initio methods of Coupled Cluster type have been employed to determine the equilibrium geometries, the spectroscopic constants and the bonding energies of the possible complexes between noble gases and hydrogen. We have first performed an extensive study of the associations ArnH3+ possible with Argon (the first noble gas which rose questions in the area of Jupiter's poles). We have found that several Argon atoms can be stabilized around the H3+ ion, the first complexation being in the plane of the ion. The spectroscopic data (rotational constants, dipole moments and IR signatures) were calculated (Pauzat & Ellinger (2005)) so that the laboratory experiments and spatial observations of these species could then be carried out. From our results and previous observations on this complex (Bogey et al. (1987)) we can say that the ArH3+ ion is certainly a good candidate for

  20. Geostatistical analysis of tritium, groundwater age and other noble gas derived parameters in California.

    PubMed

    Visser, A; Moran, J E; Hillegonds, Darren; Singleton, M J; Kulongoski, Justin T; Belitz, Kenneth; Esser, B K

    2016-03-15

    Key characteristics of California groundwater systems related to aquifer vulnerability, sustainability, recharge locations and mechanisms, and anthropogenic impact on recharge are revealed in a spatial geostatistical analysis of a unique data set of tritium, noble gases and other isotopic analyses unprecedented in size at nearly 4000 samples. The correlation length of key groundwater residence time parameters varies between tens of kilometers ((3)H; age) to the order of a hundred kilometers ((4)Heter; (14)C; (3)Hetrit). The correlation length of parameters related to climate, topography and atmospheric processes is on the order of several hundred kilometers (recharge temperature; δ(18)O). Young groundwater ages that highlight regional recharge areas are located in the eastern San Joaquin Valley, in the southern Santa Clara Valley Basin, in the upper LA basin and along unlined canals carrying Colorado River water, showing that much of the recent recharge in central and southern California is dominated by river recharge and managed aquifer recharge. Modern groundwater is found in wells with the top open intervals below 60 m depth in the southeastern San Joaquin Valley, Santa Clara Valley and Los Angeles basin, as the result of intensive pumping and/or managed aquifer recharge operations.

  1. Thermal diffusion factors and intermolecular potentials for noble gas-SF sub 6 systems

    SciTech Connect

    Taylor, W.L.; Hurly, J.J. Cincinnati Univ., OH . Dept. of Chemistry)

    1990-01-01

    Experimental thermal diffusion factors for equimolar mixtures of He-, Ne-, Ar-, Kr-, and Xe-SF{sub 6} have been measured in the temperature range from 225 to 500 K. The data were obtained in a 20-tube trennschaukel, or swing separator.'' The systems containing the four lighter noble gases all exhibited a normal'' thermal diffusion factor, {alpha}{sub T}, that is concentration of the heavy species, SF{sub 6}, in the cold region of the apparatus and increase of {alpha}{sub T} with temperature. Xe-SF{sub 6}, the system with the smallest mass difference, exhibited abnormal'' behavior. The spherically symmetric Pack potentials were used to calculate the thermal diffusion factor with reasonable success. Recently published dipole-dipole dispersion coefficients were used to construct intermolecular potentials of the Hartree-Fock-Dispersion functional form with individually damped attractive terms. The potentials, when tested against the available transport and thermodynamic data, improved the fit to experiment in almost all cases. 35 refs., 7 figs., 2 tabs.

  2. The Role of Boron-Chloride and Noble Gas Isotope Ratios in TVZ Geothermal Systems

    SciTech Connect

    Hulston, J.R.

    1995-01-01

    The model of the geothermal system in which deep circulating groundwater containing noble gases, at air saturated water concentrations, mixes with hot fluids of mantle origin at depth, is extended to include the effect of interaction of the ascending fluid with both solid and gaseous phases of basement (or other) rocks en route to the surface. It is demonstrated that this interaction is responsible for most of the CO{sub 2} in the Taupo Volcanic Zone (TVZ) geothermal systems. It is proposed that the modeling of this interaction might be accomplished by techniques similar to those used for the understanding of the oxygen isotope shift found in geothermal systems. The water rock interaction experiments of Ellis and Mahon (1964, 1967) provides some data on the kinetic rates for B and Cl dissolution from rocks likely to be encountered in the geothermal system, but further information on the behavior of B may be needed. If these problems can be overcome this modeling technique has promise for the estimation of the recharge of geothermal systems and hence the sustainability of these systems.

  3. Ground-Water Temperature, Noble Gas, and Carbon Isotope Data from the Espanola Basin, New Mexico

    USGS Publications Warehouse

    Manning, Andrew H.

    2009-01-01

    Ground-water samples were collected from 56 locations throughout the Espanola Basin and analyzed for general chemistry (major ions and trace elements), carbon isotopes (delta 13C and 14C activity) in dissolved inorganic carbon, noble gases (He, Ne, Ar, Kr, Xe, and 3He/4He ratio), and tritium. Temperature profiles were measured at six locations in the southeastern part of the basin. Temperature profiles suggest that ground water generally becomes warmer with distance from the mountains and that most ground-water flow occurs at depths 50 years old, consistent with the 14C ages. Terrigenic He (Heterr) concentrations in ground water are high (log Delta Heterr of 2 to 5) throughout much of the basin. High Heterr concentrations are probably caused by in situ production in the Tesuque Formation from locally high concentrations of U-bearing minerals (Northeast zone only), or by upward diffusive/advective transport of crustal- and mantle-sourced He possibly enhanced by basement piercing faults, or by both. The 3He/4He ratio of Heterr (Rterr) is commonly high (Rterr/Ra of 0.3-2.0, where Ra is the 3He/4He ratio in air) suggesting that Espanola Basin ground water commonly contains mantle-sourced He. The 3He/4He ratio of Heterr is generally the highest in the western and southern parts of the basin, closest to the western border fault system and the Quaternary to Miocene volcanics of the Jemez Mountains and Cerros del Rio.

  4. EFFECTS OF ALTERNATE ANTIFOAM AGENTS, NOBLE METALS, MIXING SYSTEMS AND MASS TRANSFER ON GAS HOLDUP AND RELEASE FROM NONNEWTONIAN SLURRIES

    SciTech Connect

    Guerrero, H; Mark Fowley, M; Charles Crawford, C; Michael Restivo, M; Robert Leishear, R

    2007-12-24

    Gas holdup tests performed in a small-scale mechanically-agitated mixing system at the Savannah River National Laboratory (SRNL) were reported in 2006. The tests were for a simulant of waste from the Hanford Tank 241-AZ-101 and featured additions of DOW Corning Q2-3183A Antifoam agent. Results indicated that this antifoam agent (AFA) increased gas holdup in the waste simulant by about a factor of four and, counter intuitively, that the holdup increased as the simulant shear strength decreased (apparent viscosity decreased). These results raised questions about how the AFA might affect gas holdup in Hanford Waste Treatment and Immobilization Plant (WTP) vessels mixed by air sparging and pulse-jet mixers (PJMs). And whether the WTP air supply system being designed would have the capacity to handle a demand for increased airflow to operate the sparger-PJM mixing systems should the AFA increase retention of the radiochemically generated flammable gases in the waste by making the gas bubbles smaller and less mobile, or decrease the size of sparger bubbles making them mix less effectively for a given airflow rate. A new testing program was developed to assess the potential effects of adding the DOW Corning Q2-3183A AFA to WTP waste streams by first confirming the results of the work reported in 2006 by Stewart et al. and then determining if the AFA in fact causes such increased gas holdup in a prototypic sparger-PJM mixing system, or if the increased holdup is just a feature of the small-scale agitation system. Other elements of the new program include evaluating effects other variables could have on gas holdup in systems with AFA additions such as catalysis from trace noble metals in the waste, determining mass transfer coefficients for the AZ-101 waste simulant, and determining whether other AFA compositions such as Dow Corning 1520-US could also increase gas holdup in Hanford waste. This new testing program was split into two investigations, prototypic sparger

  5. 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

  6. Quantifying air-sea gas exchange using noble gases in a coastal upwelling zone

    NASA Astrophysics Data System (ADS)

    Manning, C. C.; Stanley, R. H. R.; Nicholson, D. P.; Squibb, M. E.

    2016-05-01

    The diffusive and bubble-mediated components of air-sea gas exchange can be quantified separately using time-series measurements of a suite of dissolved inert gases. We have evaluated the performance of four published air-sea gas exchange parameterizations using a five-day time-series of dissolved He, Ne, Ar, Kr, and Xe concentration in Monterey Bay, CA. We constructed a vertical model including surface air-sea gas exchange and vertical diffusion. Diffusivity was measured throughout the cruise from profiles of turbulent microstructure. We corrected the mixed layer gas concentrations for an upwelling event that occurred partway through the cruise. All tested parameterizations gave similar results for Ar, Kr, and Xe; their air-sea fluxes were dominated by diffusive gas exchange during our study. For He and Ne, which are less soluble, and therefore more sensitive to differences in the treatment of bubble-mediated exchange, the parameterizations gave widely different results with respect to the net gas exchange flux and the bubble flux. This study demonstrates the value of using a suite of inert gases, especially the lower solubility ones, to parameterize air-sea gas exchange.

  7. Martian fluid and Martian weathering signatures identified in Nakhla, NWA 998 and MIL 03346 by halogen and noble gas analysis

    NASA Astrophysics Data System (ADS)

    Cartwright, J. A.; Gilmour, J. D.; Burgess, R.

    2013-03-01

    We report argon (Ar) noble gas, Ar-Ar ages and halogen abundances (Cl, Br, I) of Martian nakhlites Nakhla, NWA 998 and MIL 03346 to determine the presence of Martian hydrous fluids and weathering products. Neutron-irradiated samples were either crushed and step-heated (Nakhla only), or simply step-heated using a laser or furnace, and analysed for noble gases using an extension of the 40Ar-39Ar technique to determine halogen abundances. The data obtained provide the first isotopic evidence for a trapped fluid that is Cl-rich, has a strong correlation with 40ArXS (40ArXS = 40Armeasured - 40Arradiogenic) and displays 40ArXS/36Ar of ˜1000 - consistent with the Martian atmosphere. This component was released predominantly in the low temperature and crush experiments, which may suggest a fluid inclusion host. For the halogens, we observe similar Br/Cl and I/Cl ratios between the nakhlites and terrestrial reservoirs, which is surprising given the absence of crustal recycling, organic matter and frequent fluid activity on Mars. In particular, Br/Cl ratios in our Nakhla samples (especially olivine) are consistent with previously analysed Martian weathering products, and both low temperature and crush analyses show a similar trend to the evaporation of seawater. This may indicate that surface brines play an important role on Mars and on halogen assemblages within Martian meteorites and rocks. Elevated I/Cl ratios in the low temperature NWA 998 and MIL 03346 releases may relate to in situ terrestrial contamination, though we are unable to distinguish between low temperature terrestrial or Martian components. Whilst estimates of the amount of water present based on the 36Ar concentrations are too high to be explained by a fluid component alone, they are consistent with a mixed-phase inclusion (gas and fluid) or with shock-implanted Martian atmospheric argon. The observed fluid is dilute (low salinity, but high Br/Cl and I/Cl ratios), contains a Martian atmospheric component

  8. 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.

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

    NASA Astrophysics Data System (ADS)

    Farley, Kenneth; McInnes, Brent; Patterson, Desmond

    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.

  10. Tracing groundwater input into Lake Vanda, Wright Valley, Antarctica using major ions, stable isotopes and noble gas

    NASA Astrophysics Data System (ADS)

    Dowling, C. B.; Poreda, R. J.; Snyder, G. T.

    2008-12-01

    The McMurdo Dry Valleys (MDV), Antarctica, is the largest ice-free region on Antarctica. Lake Vanda, located in central Wright Valley, is the deepest lake among the MDV lakes. It has a relatively fresh water layer above 50 m with a hypersaline calcium-chloride brine below (50-72 m). The Onyx River is the only stream input into Lake Vanda. It flows westward from the coastal Lower Wright Glacier and discharges into Lake Vanda. Suggested by the published literature and this study, there has been and may still be groundwater input into Lake Vanda. Stable isotopes, major ions, and noble gas data from this study coupled with previously published data indicate that the bottom waters of Lake Vanda have had significant contributions from a deep groundwater system. The dissolved gas of the bottom waters of Lake Vanda display solubility concentrations rather than the Ar-enriched dissolved gas seen in the Taylor Valley lakes (such as Lake Bonney). The isotopic data indicate that the bottom calcium-chloride-brine of Lake Vanda has undergone very little evaporation. The calcium-chloride chemistry of the groundwater that discharges into Lake Vanda most likely results from the chemical weathering and dissolution of cryogenic evaporites (antarcticite and gypsum) within the glacial sediments of Wright Valley. The high calcium concentrations of the brine have caused gypsum to precipitate on the lake bottom. Our work also supports previous physical and chemical observations suggesting that the upper portion actively circulates and the hypersaline bottom layer does not. The helium and calcium chloride values are concentrated at the bottom, with a very narrow transition layer between it and the above fresh water. If the freshwater layer did not actively circulate, then diffusion over time would have caused the helium and calcium chloride to slowly permeate upwards through the water column.

  11. ENVIRONMENTAL APPLICATION OF GAS CHROMATOGRAPHY/ATOMIC EMISSION DETECTION

    EPA Science Inventory

    A gas chromatography/atomic emission detector (GC/AED) system has been evaluated for its applicability to environmental analysis. Detection limits, elemental response factors, and regression analysis data were determined for 58 semivolatile environmental contaminants. Detection l...

  12. ENVIRONMENTAL APPLICATION OF GAS CHROMATOGRAPHY/ATOMIC EMISSION DETECTION

    EPA Science Inventory

    A gas chromatography/atomic emission detector (GC/AED) system has been evaluated for its applicability to environmental analysis. Detection limits, elemental response factors, and regression analysis data were determined for 58 semivolatile environmental contaminants. Detection l...

  13. Itinerant ferromagnetism in a two-dimensional atomic gas

    SciTech Connect

    Conduit, G. J.

    2010-10-15

    Motivated by the first experimental evidence of ferromagnetic behavior in a three-dimensional ultracold atomic gas, we explore the possibility of itinerant ferromagnetism in a trapped two-dimensional atomic gas. Firstly, we develop a formalism that demonstrates how quantum fluctuations drive the ferromagnetic reconstruction first order, and consider the consequences of an imposed population imbalance. Secondly, we adapt this formalism to elucidate the key experimental signatures of ferromagnetism in a realistic trapped geometry.

  14. Barrierless growth of precursor-free, ultrafast laser-fragmented noble metal nanoparticles by colloidal atom clusters - A kinetic in situ study.

    PubMed

    Jendrzej, Sandra; Gökce, Bilal; Amendola, Vincenzo; Barcikowski, Stephan

    2016-02-01

    Unintended post-synthesis growth of noble metal colloids caused by excess amounts of reactants or highly reactive atom clusters represents a fundamental problem in colloidal chemistry, affecting product stability or purity. Hence, quantified kinetics could allow defining nanoparticle size determination in dependence of the time. Here, we investigate in situ the growth kinetics of ps pulsed laser-fragmented platinum nanoparticles in presence of naked atom clusters in water without any influence of reducing agents or surfactants. The nanoparticle growth is investigated for platinum covering a time scale of minutes to 50days after nanoparticle generation, it is also supplemented by results obtained from gold and palladium. Since a minimum atom cluster concentration is exceeded, a significant growth is determined by time resolved UV/Vis spectroscopy, analytical disc centrifugation, zeta potential measurement and transmission electron microscopy. We suggest a decrease of atom cluster concentration over time, since nanoparticles grow at the expense of atom clusters. The growth mechanism during early phase (<1day) of laser-synthesized colloid is kinetically modeled by rapid barrierless coalescence. The prolonged slow nanoparticle growth is kinetically modeled by a combination of coalescence and Lifshitz-Slyozov-Wagner kinetic for Ostwald ripening, validated experimentally by the temperature dependence of Pt nanoparticle size and growth quenching by Iodide anions. Copyright © 2015. Published by Elsevier Inc.

  15. Uranium and noble gas isotopes to decipher naturally-occuring radionuclide release into aquifers

    NASA Astrophysics Data System (ADS)

    Méjean, Pauline; Pinti, Daniele Luigi; Ghaleb, Bassam; Larocque, Marie

    2017-04-01

    phase. U and noble gases could be a new tool for understanding mechanism of release of radionuclides in aquifers.

  16. Improved atomic resonance gas cell for use in frequency standards

    NASA Technical Reports Server (NTRS)

    Huggett, G. R.

    1968-01-01

    Atomic resonance gas cell maintains a stable operating frequency in the presence of pressure fluctuations in the ambient atmosphere. The new cell includes an envelope which is transparent to radiation in the optical region and to microwave energy at the atomic resonance frequency of the alkali-metal vapor within the envelope.

  17. Investigations of laser pumped gas cell atomic frequency standard

    NASA Technical Reports Server (NTRS)

    Volk, C. H.; Camparo, J. C.; Fueholz, R. P.

    1982-01-01

    The performance characteristics of a rubidium gas cell atomic frequency standard might be improved by replacing the standard rubidium discharge lamp with a single mode laser diode. Aspects of the laser pumped gas cell atomic clock studied include effects due to laser intensity, laser detuning, and the choice of the particular atomic absorption line. Results indicate that the performance of the gas cell clock may be improved by judicious choice of the operating parameters of the laser diode. The laser diode also proved to be a valuable tool in investigating the operation of the conventional gas cell clock. Results concerning linewidths, the light shift effect and the effect of isotopic spin exchange in the conventional gas cell clock are reported.

  18. Comparative Study on the Noble-Gas Binding Ability of BeX Clusters (X = SO4, CO3, O).

    PubMed

    Saha, Ranajit; Pan, Sudip; Merino, Gabriel; Chattaraj, Pratim K

    2015-06-25

    Ab initio computations are carried out to assess the noble gas (Ng) binding capability of BeSO4 cluster. We have further compared the stability of NgBeSO4 with that of the recently detected NgBeCO3 cluster. The Ng-Be bond in NgBeCO3 is somewhat weaker than that in NgBeO cluster. In NgBeSO4, the Ng-Be bond is found to be stronger compared with not only the Ng-Be bond in NgBeCO3 but also that in NgBeO, except the He case. The Ar-Rn-bound BeSO4 analogues are viable even at room temperature. The Wiberg bond indices of Be-Ng bonds and the degree of electron transfer from Ng to Be are somewhat larger in NgBeSO4 than those in NgBeCO3 and NgBeO. Electron density and energy decomposition analyses are performed in search of the nature of interaction in the Be-Ng bond in NgBeSO4. The orbital energy term (ΔE(orb)) contributes the maximum (ca. 80-90%) to the total attraction energy. The Ar/Kr/Xe/Rn-Be bonds in NgBeSO4 could be of partial covalent type with a gradual increase in covalency along Ar to Rn.

  19. Ultrahigh sensitivity heavy noble gas detectors for long-term monitoring and monitoring air. 1998 annual progress report

    SciTech Connect

    Valentine, J.D.; Gross, K.

    1998-06-01

    'The primary objective of this research project is to develop heavy noble gas (krypton, xenon, and radon) detectors for: (1) long-term monitoring of transuranic waste, spent fuel, and other uranium and thorium bearing wastes, and (2) alpha particle air monitors that discriminate between radon emissions and other alpha emitters. A University of Cincinnati/Argonne National Laboratory (UC/ANL) Team has been assembled to complete this detector development project. DOE needs that are addressed by this project include improved long-term monitoring capability and improved air monitoring capability during remedial activities. Successful development and implementation of the proposed detection systems could significantly improve current capabilities with relatively simple and inexpensive equipment. As of June 1, 1998, the UC/ANL Team has: (1) made significant progress toward characterizing the fluid transfer process which is the basis for this detector development project and (2) evaluated several radiation detectors and several potential pulse processing schemes. The following discussion describes the progress made during the first year of this project and the implications of this progress.'

  20. Using noble-gas and stable-isotope data to determine groundwater origin and flow regimes: Application to the Ceneri Base Tunnel (Switzerland)

    NASA Astrophysics Data System (ADS)

    Tomonaga, Yama; Marzocchi, Roberto; Pera, Sebastian; Pfeifer, Hans-Rudolf; Kipfer, Rolf; Decrouy, Laurent; Vennemann, Torsten

    2017-02-01

    Tunnel drilling provides a unique opportunity to sample and study deep groundwaters that are otherwise difficult to access. Understanding deep groundwater flow is of primary importance in assessing the possible impacts of tunnelling on hydrogeological systems. During this study, water was sampled for noble-gas analysis from tunnel inflows in the AlpTransit Ceneri Base Tunnel (Canton Ticino, southern Switzerland), which passes through an area mainly characterized by metamorphic rocks (gneiss). Furthermore, water was sampled from springs located in the same geological environment. Based on the measurement of noble-gas concentrations and isotope ratios, tritium concentrations, the stable isotope composition of hydrogen (δ2H) and oxygen (δ18O), and the concentrations of major ions in the water, a conceptual hydrogeological model was established for this case study that allowed the most probable origin of the groundwaters sampled at different locations to be determined. The measured abundances of 3He, 4He, and 20Ne allow the geochemical characterization of old groundwaters strongly enriched in terrigenic helium of crustal origin and the identification of mixing with water that circulates preferentially through cataclastic structures. Noble-gas concentrations and isotope ratios as well as tritium are useful proxies for the characterization of faults that may be critical for tunnel drilling because of their active hydrogeological role and their influence on the mechanics of the rocks.

  1. Energy and spectral enhancement of femtosecond supercontinuum in a noble gas using a weak seed.

    PubMed

    Ensley, Trenton R; Fishman, Dmitry A; Webster, Scott; Padilha, Lazaro A; Hagan, David J; Van Stryland, Eric W

    2011-01-17

    We experimentally demonstrate that the use of a weak seed pulse of energy less than 0.4% of the pump results in a spectral energy enhancement that spans over 2 octaves and a total energy enhancement of more than 3 times for supercontinua generated by millijoule level femtosecond pulses in Krypton gas. Strong four-wave mixing of the pump-seed pulse interacting in the gas is observed. The spectral irradiance generated from the seeding process is sufficiently high to use white-light continuum as an alternative to conventional tunable sources of radiation for applications such as nonlinear optical spectroscopy.

  2. Multi-wavelength Study of Diffuse Atomic and Molecular Gas

    NASA Astrophysics Data System (ADS)

    Federman, Steven Robert; Rice, Johnathan; Flagey, Nicolas; Ritchey, Adam M.; Welty, Daniel E.; Goldsmith, Paul; Langer, William; Pineda, Jorge L.; Lambert, David L.; Lemaire, Jean-Louis

    2017-06-01

    Diffuse atomic and molecular gas is revealed through a combination of absorption lines against background targets and emission. We describe a project that combines results on ultraviolet (UV) and visible absorption with those obtained from the Herschel key program GOTC+ (Galactic Observations of Terahertz C+) to develop a comprehensive picture of neutral diffuse gas in the Galaxy. [C II], H I, and CO emission acquired for the GOTC+ survey reveal the presence of warm neutral atomic gas, cold neutral atomic gas, CO-dark H2 gas (molecular gas not seen in CO emission), and denser molecular gas in different kinematic components. We derive the component structure (number of clouds and their column densities) seen in absorption at visible wavelengths from Ca II, Ca I, K I, CH, CH+, and CN and compare that to the emission from [C II], H I, and CO and its isotopologues. Absorption lines from additional atoms (including C I, O I, and Ni II) and molecules (CO) from UV spectra obtained with the Hubble Space Telescope are used to expand the kinematic correspondences. Preliminary results on physical conditions (gas temperature and density) inferred from analyses of CN chemistry and excitation of neutral and singly-ionized carbon, neutral oxygen, and CO are also presented.

  3. Optimization of buffer gas pressure for Rb atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Chen, Chang; Liu, Xiaohu; Qu, Tianliang; Yang, Kaiyong

    2015-08-01

    The optimization of buffer gas pressure is very important to improve the performance of the rubidium (Rb) atomic magnetometer. In this paper we briefly introduce the basic principle and the experimental method of the rubidium magnetometer based on Faraday rotation effect, and describe the factors affecting the magnetometer sensitivity, then analyze and summarize the mechanism of the influence of spin-exchange, spin-destruction collisions, radiation trapping and the spin diffusion on spin relaxation of Rb atoms. Based on this, the relationship between the rubidium magnetometer sensitivity, the spin relaxation rate and the gas chamber conditions (buffer gas pressure, the bubble radius, measuring temperature) is established. Doing calculations by the simulation software, how the magnetometer sensitivity and the relaxation rate vary with the gas chamber conditions can be seen; finally, the optimal values of the buffer gas pressure under certain gas chamber conditions are obtained. The work is significant for the engineering development of rubidium magnetometer.

  4. Refined potentials for rare gas atom adsorption on rare gas and alkali-halide surfaces

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Heinbockel, J. H.; Outlaw, R. A.

    1985-01-01

    The utilization of models of interatomic potential for physical interaction to estimate the long range attractive potential for rare gases and ions is discussed. The long range attractive force is calculated in terms of the atomic dispersion properties. A data base of atomic dispersion parameters for rare gas atoms, alkali ion, and halogen ions is applied to the study of the repulsive core; the procedure for evaluating the repulsive core of ion interactions is described. The interaction of rare gas atoms on ideal rare gas solid and alkali-halide surfaces is analyzed; zero coverage absorption potentials are derived.

  5. Simultaneous measurement of rock permeability and effective porosity using laser-polarized noble gas NMR

    NASA Astrophysics Data System (ADS)

    Wang, R.; Mair, R. W.; Rosen, M. S.; Cory, D. G.; Walsworth, R. L.

    2004-08-01

    We report simultaneous measurements of the permeability and effective porosity of oil-reservoir rock cores using one-dimensional NMR imaging of the penetrating flow of laser-polarized xenon gas. The permeability result agrees well with industry standard techniques, whereas effective porosity is not easily determined by other methods. This NMR technique may have applications to the characterization of fluid flow in a wide variety of porous and granular media.

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

    PubMed

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

    2008-10-14

    The interaction of the inert gases Rn and element 118 with various surfaces has been studied on the basis of fully relativistic ab initio Dirac-Coulomb CCSD(T) calculations of atomic properties. The calculated polarizability of element 118, 46.3 a.u., is the largest in group 18, the ionization potential is the lowest at 8.91 eV, and the estimated atomic radius is the largest, 4.55 a.u. These extreme values reflect, in addition to the general trends in the Periodic Table, the relativistic expansion and destabilization of the outer valence 7p(3/2) orbital. Van der Waals coefficients C(3) and adsorption enthalpies DeltaH(ads) of Ne through element 118 on noble metals and inert surfaces, such as quartz, ice, Teflon, and graphite, were calculated in a physisorption model using the atomic properties obtained. The C(3) coefficients were shown to steadily increase in group 18, while the increase in DeltaH(ads) from Ne to Rn does not continue to element 118: The large atomic radius of the latter element is responsible for a decrease in the interaction energy. We therefore predict that experimental distinction between Rn and 118 by adsorption on these types of surfaces will not be feasible. A possible candidate for separating the two elements is charcoal; further study is needed to test this possibility.

  7. Structure and properties of the radiation-induced intermediates produced from HCN in noble gas matrices

    NASA Astrophysics Data System (ADS)

    Kameneva, Svetlana V.; Tyurin, Daniil A.; Feldman, Vladimir I.

    2016-07-01

    In this work we report the results of systematic studies on the radiation-induced transformations in HCN/Ng systems (Ng=Ne, Ar, Kr or Xe) at 7 K using a combination of FTIR and EPR spectroscopy. It was shown that HCN underwent efficient decomposition producing H atoms, CN radicals and HNC isomer. The thermally induced reactions of H atoms in different matrices result in the formation of two isomeric radicals, H2CN and trans-HCNH, the former being predominated. The temperature dependent dynamics of CN and H2CN radicals in a krypton matrix was observed by EPR spectroscopy in solid krypton. The vibrational frequencies, IR intensities and magnetic resonance parameters of H2CN and trans-HCNH radicals calculated at the CCSD(T) level are in reasonable agreement with the experimental results. It was found that HCNH radical could be effectively bleached with visible light. The comparison of experimental and computational data made it possible to assign a new vibrational band at 918 cm-1 in an Ar matrix (and the corresponding bands in Kr and Xe) to trans-HCNH radical. In addition, HKrCN was found in the case of krypton, whereas HXeCN and HXeNC were produced in solid xenon. The reaction mechanisms and contribution of different channels are discussed.

  8. Development toward a double focusing isotopic separator for noble gas isotope enrichment.

    PubMed

    Lavielle, Bernard; Thomas, Bertrand; Gilabert, Eric; Canchel, Gregory; Horlait, Denis; Topin, Sylvain; Pointurier, Fabien; Moulin, Christophe

    2016-10-01

    A double focusing sector field mass filter used in Nier-Johnson geometry has been built in order to perform Kr isotope enrichment for (81) Kr and (85) Kr isotopes. The principle consists in implanting Kr(+) ions accelerated at 7 keV in Al foils after separation using the magnetic sector. A specific ion source has been designed capable of generating high Kr(+) ion beams (>0.5 μA) to transfer into the collecting Al foils in 3 to 5 h significant fractions of large Kr samples (10(15) to 10(16) atoms) initially introduced in the instrument. Implanted Kr isotopes can be further selectively released from the Al foil by surface ablation using an infrared laser beam. Implantation yields and enrichment factors are measured using a conventional mass spectrometer. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  9. Common versus noble Bacillus subtilis differentially responds to air and argon gas plasma.

    PubMed

    Winter, Theresa; Bernhardt, Jörg; Winter, Jörn; Mäder, Ulrike; Schlüter, Rabea; Weltmann, Klaus-Dieter; Hecker, Michael; Kusch, Harald

    2013-09-01

    The applications of low-temperature plasma are not only confined to decontamination and sterilization but are also found in the medical field in terms of wound and skin treatment. For the improvement of already established and also for new plasma techniques, in-depth knowledge on the interactions between plasma and microorganism is essential. In an initial study, the interaction between growing Bacillus subtilis and argon plasma was investigated by using a growth chamber system suitable for low-temperature gas plasma treatment of bacteria in liquid medium. In this follow-up investigation, a second kind of plasma treatment-namely air plasma-was applied. With combined proteomic and transcriptomic analyses, we were able to investigate the plasma-specific stress response of B. subtilis toward not only argon but also air plasma. Besides an overlap of cellular responses due to both argon and air plasma treatment (DNA damage and oxidative stress), a variety of gas-dependent cellular responses such as growth retardation and morphological changes were observed. Only argon plasma treatments lead to a phosphate starvation response whereas air plasma induced the tryptophan operon implying damage by photooxidation. Biological findings were supported by the detection of reactive plasma species by optical emission spectroscopy and Fourier transformed infrared spectroscopy measurements. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Understanding the interaction of injected CO2 and reservoir fluids in the Cranfield enhanced oil recovery (EOR) field (MS, USA) by non-radiogenic noble gas isotopes

    NASA Astrophysics Data System (ADS)

    Gyore, Domokos; Stuart, Finlay; Gilfillan, Stuart

    2016-04-01

    Identifying the mechanism by which the injected CO2 is stored in underground reservoirs is a key challenge for carbon sequestration. Developing tracing tools that are universally deployable will increase confidence that CO2 remains safely stored. CO2 has been injected into the Cranfield enhanced oil recovery (EOR) field (MS, USA) since 2008 and significant amount of CO2 has remained (stored) in the reservoir. Noble gases (He, Ne, Ar, Kr, Xe) are present as minor natural components in the injected CO2. He, Ne and Ar previously have been shown to be powerful tracers of the CO2 injected in the field (Györe et al., 2015). It also has been implied that interaction with the formation water might have been responsible for the observed CO2 loss. Here we will present work, which examines the role of reservoir fluids as a CO2 sink by examining non-radiogenic noble gas isotopes (20Ne, 36Ar, 84Kr, 132Xe). Gas samples from injection and production wells were taken 18 and 45 months after the start of injection. We will show that the fractionation of noble gases relative to Ar is consistent with the different degrees of CO2 - fluid interaction in the individual samples. The early injection samples indicate that the CO2 injected is in contact with the formation water. The spatial distribution of the data reveal significant heterogeneity in the reservoir with some wells exhibiting a relatively free flow path, where little formation water is contacted. Significantly, in the samples, where CO2 loss has been previously identified show active and ongoing contact. Data from the later stage of the injection shows that the CO2 - oil interaction has became more important than the CO2 - formation water interaction in controlling the noble gas fingerprint. This potentially provides a means to estimate the oil displacement efficiency. This dataset is a demonstration that noble gases can resolve CO2 storage mechanisms and its interaction with the reservoir fluids with high resolution

  11. Canadian Shield brine from the Con Mine, Yellowknife, NT, Canada: Noble gas evidence for an evaporated Palaeozoic seawater origin mixed with glacial meltwater and Holocene recharge

    NASA Astrophysics Data System (ADS)

    Greene, Shane; Battye, Nick; Clark, Ian; Kotzer, Tom; Bottomley, Dennis

    2008-08-01

    Dissolved noble gas concentrations were measured in high salinity (270 g/L) Ca(Na)-Cl groundwaters from the Con Mine, Yellowknife, Canada in an effort to discriminate between two possible origins, as either a brine generated by evaporative enrichment in a Paleozoic inland sea, or marine water concentrated by freezing during glacial times. Major ion and isotope geochemistry indicate that brines from the deepest level remain relatively undisturbed by mixing with modern water introduced by mining. Mixing calculations are used to quantify fractions of brine, glacial meltwater and modern water. From this, noble gas concentrations were corrected for excess air with Ne and normalized to 100% brine solution. Over-pressuring of helium and argon in the brine provide age constraints based on the accumulation of geogenic 4He and 40Ar. Radiogenic age calculations together with the local geological history suggest brine emplacement during early Palaeozoic time, likely during the Devonian when evaporitic inland seas existed in this region. The concentrations of the atmospherically derived noble gases in the brine fraction (Kr = 1.4E-8, Xe = 8.5E-10 cc/ccO) are close to atmospheric equilibrium for brine at 25 °C (Kr = 7.3E-9, Xe = 8.0E-10 cc/ccO), but are far lower than would be expected for closed-system concentration of seawater by freezing (Kr = 2.8E-6, Xe = 4.2E-7 cc/ccO). Thus, despite the complicated mixing history of the brine, the atmospheric and geogenic noble gases provide strong evidence for an origin as air-equilibrated brine from evaporated Paleozoic seawater, which infiltrated via density displacement through existing fractures and faults into the Canadian Shield.

  12. Creation of ultracold molecules from a Fermi gas of atoms.

    PubMed

    Regal, Cindy A; Ticknor, Christopher; Bohn, John L; Jin, Deborah S

    2003-07-03

    Following the realization of Bose-Einstein condensates in atomic gases, an experimental challenge is the production of molecular gases in the quantum regime. A promising approach is to create the molecular gas directly from an ultracold atomic gas; for example, bosonic atoms in a Bose-Einstein condensate have been coupled to electronic ground-state molecules through photoassociation or a magnetic field Feshbach resonance. The availability of atomic Fermi gases offers the prospect of coupling fermionic atoms to bosonic molecules, thus altering the quantum statistics of the system. Such a coupling would be closely related to the pairing mechanism in a fermionic superfluid, predicted to occur near a Feshbach resonance. Here we report the creation and quantitative characterization of ultracold 40K2 molecules. Starting with a quantum degenerate Fermi gas of atoms at a temperature of less than 150 nK, we scan the system over a Feshbach resonance to create adiabatically more than 250,000 trapped molecules; these can be converted back to atoms by reversing the scan. The small binding energy of the molecules is controlled by detuning the magnetic field away from the Feshbach resonance, and can be varied over a wide range. We directly detect these weakly bound molecules through their radio-frequency photodissociation spectra; these probe the molecular wavefunction, and yield binding energies that are consistent with theory.

  13. 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.

  14. PARAMETRIC EFFECTS OF ANTI-FOAM COMPOSITION, SIMULANT PROPERTIES AND NOBLE METALS ON THE GAS HOLDUP AND RELEASE OF A NON-NEWTONIAN WASTE SLURRY SIMULANT

    SciTech Connect

    Guerrero, H; Charles Crawford, C; Mark Fowley, M

    2008-08-07

    Gas holdup tests were performed in bench-scale and small-scale mechanically-agitated mixing systems at the Savannah River National Laboratory (SRNL) for a simulant of waste from the Hanford Tank 241-AZ-101. These featured additions of DOW Corning Q2-3183A anti-foam agent. Results indicated that this anti-foam agent (AFA) increased gas holdup in the waste simulant by about a factor of four and, counter-intuitively, that the holdup increased as the non-newtonian simulant shear strength decreased (apparent viscosity decreased). Such results raised the potential of increased flammable gas retention in Hanford Waste Treatment and Immobilization Plant (WTP) vessels mixed by air sparging and pulse-jet mixers (PJMs) during a Design Basis Event (DBE). Additional testing was performed to determine the effects of simulant properties, composition of alternate AFAs, and presence of trace noble metals. Key results are that: (1) Increased gas holdup resulting from addition of Q2-3183A is due to a decrease in surface tension that supports small bubbles which have low rise velocities. (2) Dow Corning 1520-US AFA shows it to be a viable replacement to Dow Corning Q2-3183A AFA. This alternative AFA, however, requires significantly higher dosage for the same anti-foam function. (3) Addition of noble metals to the AZ-101 waste simulant does not produce a catalytic gas retention effect with the AFA.

  15. New method of 85Kr reduction in a noble gas based low-background detector

    NASA Astrophysics Data System (ADS)

    Akimov, D. Yu.; Bolozdynya, A. I.; Burenkov, A. A.; Hall, C.; Kovalenko, A. G.; Kuzminov, V. V.; Simakov, G. E.

    2017-04-01

    Krypton-85 is an anthropogenic beta-decaying isotope which produces low energy backgrounds in dark matter and neutrino experiments, especially those based upon liquid xenon. Several technologies have been developed to reduce the Kr concentration in such experiments. We propose to augment those separation technologies by first adding to the xenon an 85Kr-free sample of krypton in an amount much larger than the natural krypton that is already present. After the purification system reduces the total Kr concentration to the same level, the final 85Kr concentration will be reduced even further by the dilution factor. A test cell for measurement of the activity of various Kr samples has been assembled, and the activity of 25-year-old krypton has been measured. The measured activity agrees well with the expected activity accounting for the 85Kr abundance of the earth's atmosphere in 1990 and the half-life of the isotope. Additional tests with a Kr sample produced in the year 1944 (before the atomic era) have been done in order to demonstrate the sensitivity of the test cell.

  16. The noble gas argon modifies extracellular signal-regulated kinase 1/2 signaling in neurons and glial cells.

    PubMed

    Fahlenkamp, Astrid V; Rossaint, Rolf; Haase, Hajo; Al Kassam, Hussam; Ryang, Yu-Mi; Beyer, Cordian; Coburn, Mark

    2012-01-15

    Recently, the noble gas argon has been identified as a potent neuroprotective agent, but little is known about its cellular effects. In this in vitro study, we investigated argon's influence on the extracellular signal-regulated kinase (ERK) 1/2, a ubiquitous enzyme with numerous functions in cell proliferation and survival. Primary neuronal and astroglial cell cultures and the microglial cell line BV-2 were exposed to 50 vol.% argon. Further possible effects were studied following stimulation of microglia with 50 ng/ml LPS. ERK 1/2 activation was assessed by phosphorylation state-specific western blotting, cytokine levels by real-time PCR and western blotting. Total phosphotyrosine phosphatase activity was examined with p-nitrophenylphosphate. After 30 min exposure, argon significantly activated ERK 1/2 signaling in microglia. Enhanced phosphorylation of ERK 1/2 was also found in astrocytes and neurons following argon exposure, but it lacked statistical significance. In microglia, argon did not substantially interfere with LPS-induced ERK1/2 activation and inflammatory cytokine induction. Addition of the MEK-Inhibitor U0126 abolished the induced ERK 1/2 phosphorylation. Cellular phosphatase activity and the inactivation of phosphorylated ERK 1/2 were not altered by argon. In conclusion, argon enhanced ERK 1/2 activity in microglia via the upstream kinase MEK, probably through a direct mode of activation. ERK 1/2 signaling in astrocytes and neurons in vitro was also influenced, although not with statistical significance. Whether ERK 1/2 activation by argon affects cellular functions like differentiation and survival in the brain in vivo will have to be determined in future experiments. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. The Thermo Scientific HELIX-SFT noble gas mass spectrometer: (preliminary) performance for 40Ar/39Ar geochronology

    NASA Astrophysics Data System (ADS)

    Barfod, D. N.; Mark, D. F.; Morgan, L. E.; Tomkinson, T.; Stuart, F.; Imlach, J.; Hamilton, D.

    2011-12-01

    The Thermo Scientific HELIX-platform Split Flight Tube (HELIX-SFT) noble gas mass spectrometer is specifically designed for simultaneous collection of helium isotopes. The high mass spur houses a switchable 1011 - 1012 Ω resistor Faraday cup and the low mass spur a digital pulse-counting secondary electron multiplier (SEM). We have acquired the HELIX-SFT with the specific intention to measure argon isotopes for 40Ar/39Ar geochronology. This contribution will discuss preliminary performance (resolution, reproducibility, precision etc.) with respect to measuring argon isotope ratios for 40Ar/39Ar dating of geological materials. We anticipate the greatest impact for 40Ar/39Ar dating will be increased accuracy and precision, especially as we approach the techniques younger limit. Working with Thermo Scientific we have subtly modified the source, alpha and collector slits of the HELIX-SFT mass spectrometer to improve its resolution for resolving isobaric interferences at masses 36 to 40. The enhanced performance will allow for accurate and precise measurement of argon isotopes. Preliminary investigations show that we can obtain a valley resolution of >700 and >1300 (compared to standard HELIX-SFT specifications of >400 and >700) for the high and low mass spurs, respectively. The improvement allows for full resolution of hydrocarbons (C3+) at masses 37 - 40 and almost full resolution at mass 36. The HELIX-SFT will collect data in dual collection mode with 40Ar+ ion beams measured using the switchable 1011 - 1012 Ω resistor Faraday cup and 39Ar through 36Ar measured using the SEM. The HELIX-SFT requires Faraday-SEM inter-calibration but negates the necessity to inter-calibrate multiple electron multipliers. We will further present preliminary data from the dating of mineral standards: Alder Creek sanidine, Fish Canyon sanidine and Mount Dromedary biotite (GA1550).

  18. Fluid circulation and reservoir conditions of the Los Humeros Geothermal Field (LHGF), Mexico, as revealed by a noble gas survey

    NASA Astrophysics Data System (ADS)

    Pinti, Daniele L.; Castro, M. Clara; Lopez-Hernandez, Aida; Han, Guolei; Shouakar-Stash, Orfan; Hall, Chris M.; Ramírez-Montes, Miguel

    2017-03-01

    Los Humeros Geothermal Field (LHGF) is one of four geothermal fields currently operating in Mexico, in exploitation since 1990. Located in a caldera complex filled with very low-permeability rhyolitic ignimbrites that are the reservoir cap-rock, recharge of the geothermal field is both limited and localized. Because of this, planning of any future geothermal exploitation must be based on a clear understanding of the fluid circulation. To this end, a first noble gas survey was carried out in which twenty-two production wells were sampled for He, Ne, Ar, Kr, and Xe isotope analysis. Air-corrected 3He/4He ratios (Rc) measured in the fluid, normalized to the helium atmospheric ratio (Ra; 1.384 × 10- 6), are consistently high across the field, with an average value of 7.03 ± 0.40 Ra. This value is close to that of the sub-continental upper mantle, indicating that LHGF mines heat from an active magmatic system. Freshwater recharge does not significantly affect He isotopic ratios, contributing 1-10% of the total fluid amount. The presence of radiogenic 40Ar* in the fluid suggests a fossil fluid component that might have circulated within the metacarbonate basement with radiogenic argon produced from detrital dispersed illite. Solubility-driven elemental fractionation of Ne/Ar, Kr/Ar, and Xe/Ar confirm extreme boiling in the reservoir. However, a combined analysis of these ratios with 40Ar/36Ar reveals mixing with an air component, possibly introduced by re-injected geothermal fluids.

  19. He, U, and Th Depth Profiling of Apatite and Zircon Using Laser Ablation Noble Gas Mass Spectrometry and SIMS

    NASA Astrophysics Data System (ADS)

    Monteleone, B. D.; van Soest, M. C.; Hodges, K. V.; Hervig, R.; Boyce, J. W.

    2008-12-01

    Conventional (U-Th)/He thermochronology utilizes single or multiple grain analyses of U- and Th-bearing minerals such as apatite and zircon and does not allow for assessment of spatial variation in concentration of He, U, or Th within individual crystals. As such, age calculation and interpretation require assumptions regarding 4He loss through alpha ejection, diffusive redistribution of 4He, and U and Th distribution as an initial condition for these processes. Although models have been developed to predict 4He diffusion parameters, correct for the effect of alpha ejection on calculated cooling ages, and account for the effect of U and Th zonation within apatite and zircon, measurements of 4He, U, and Th distribution have not been combined within a single crystal. We apply ArF excimer laser ablation, combined with noble gas mass spectrometry, to obtain depth profiles within apatite and zircon crystals in order to assess variations in 4He concentration with depth. Our initial results from pre-cut, pre-heated slabs of Durango apatite, each subjected to different T-t schedules, suggest a general agreement of 4He profiles with those predicted by theoretical diffusion models (Farley, 2000). Depth profiles through unpolished grains give reproducible alpha ejection profiles in Durango apatite that deviate from alpha ejection profiles predicted for ideal, homogenous crystals. SIMS depth profiling utilizes an O2 primary beam capable of sputtering tens of microns and measuring sub-micron resolution variation in [U], [Th], and [Sm]. Preliminary results suggest that sufficient [U] and [Th] zonation is present in Durango apatite to influence the form of the 4He alpha ejection profile. Future work will assess the influence of measured [U] and [Th] zonation on previously measured 4He depth profiles. Farley, K.A., 2000. Helium diffusion from apatite; general behavior as illustrated by Durango fluorapatite. J. Geophys. Res., B Solid Earth Planets 105 (2), 2903-2914.

  20. High precision nitrogen isotope measurements in oceanic basalts using a static triple collection noble gas mass spectrometer

    NASA Astrophysics Data System (ADS)

    Barry, P. H.; Hilton, D. R.; Halldórsson, S. A.; Hahm, D.; Marti, K.

    2012-01-01

    We describe a new system for the simultaneous static triple-collection of nitrogen isotopes at the <10μcm3 STP [N2] (<1 × 10-5 cm3STP; <0.5 nmol) level using a modified VG-5440 noble gas mass spectrometer. The system consists of an internal N2-STD with aδ15N value of -0.11 ± 0.22 ‰ (1σ) calibrated against an air-standard (Air-STD). The N2-STD was measured repeatedly with an average uncertainty on an individualδ15N measurement being 0.03 ‰ (1σ) versus an average single day reproducibility of 0.38 ‰ (1σ). Additional refinements include (1) monitoring of interfering CO contributions at mass 30, allowing a comprehensive CO correction to be applied to all samples, (2) quantification of procedural N2 blanks (n = 22) in both size (4.2 ± 0.5 μcm3 STP) and isotopic composition (δ15N = 12.64 ± 2.04 ‰), allowing consistent blank corrections to all samples, and (3) independent measurement of N2/Ar ratios using a quadrupole mass spectrometer (QMS). The new system was tested by measuring nitrogen isotopes (δ15N), concentrations and N2/Ar ratios on 11 submarine basalt glasses. Results show that the uncertainty on the δ15N data is improved as a consequence of multiple standards being run per day. Reduced analytical times, afforded by triple collection, also minimize sample depletion and memory effects, thus improving measurement statistics. Additionally, we show that CO corrections can be accomplished using mass 30 to monitor CO interferences, leading to substantial improvements in reproducibility and the overall accuracy of results when the contribution of CO is significant.

  1. Non-Adiabatic Atomic Transitions: Computational Cross Section Calculations of Alkali Metal-Noble Gas Collisions

    DTIC Science & Technology

    2011-09-01

    library written by Paul Swarztrauber and Richard Valent in the mid 1990s[39]. When using FFT algorithms it is important to realize that the grid sizes of...perturbation theory that the first order 145 correction to F is zero. Delos[16] states that in general due to the Hellmann- Feynman theorem the F...Physical Review, 179(1):111–123, 1969. [39] Swarztrauber, Paul and Richard Valent. “FFTPACK5”. http://www.cisl.ucar.edu/css/software/fftpack5/index.html

  2. Simulation of powder metal fabrication with high pressure gas atomization

    SciTech Connect

    Kuntz, D.W.; Payne, J.L.

    1994-12-31

    A computational/analytical technique has been developed which models the physics of high pressure gas atomization. The technique uses an uncoupled approach, such that the gas flowfield is initially calculated with a commercially-available Navier-Stokes code. The liquid metal droplet breakup, dynamics, and thermodynamics, are then calculated using the pre-computed flowfield by a separate computer program written by the authors. The atomization code models the primary breakup of the liquid metal stream, tracks the droplets resulting from primary breakup through the flowfield until they undergo secondary breakup, and then tracks the subdroplets until they breakup, solidify, or leave the flowfield region of interest. The statistical properties of the metal powder produced are then computed from the characteristics of these droplets. Comparisons between experimental measurements and computations indicate that the Navier-Stokes code is predicting the gas flowfield well, and that the atomization code is properly modeling the physics of the droplet dynamics and breakup.

  3. Atomic processes in the hot gas in our galaxy

    NASA Astrophysics Data System (ADS)

    Shelton, Robin L.

    2017-03-01

    Our galaxy contains vast regions of very hot, very low density plasma that provide scientists with unique opportunities to observe atomic processes in extreme conditions. With temperatures of ˜ 105 to ˜ 106 K, the atoms in these regions are ionized to high charge states. Collisional ionization and excitation dominate the atomic physics in the interiors of these regions, and charge exchange becomes important where the highly ionized gas borders cool gas. Examples of very hot regions include the bubbles blown by supernova explosions and the interstellar gas above and below the disk of our galaxy. Examples of charge exchange sites include the heliosphere, supernova shock fronts, and high velocity clouds. Highly ionized plasmas are primarily studied via ultraviolet and X-ray observations using telescopes mounted on satellites, rockets, or space shuttles. Observations have been made of both the emitted spectrum and the number of ions along a path. The sensitivity and spectral resolution of the observing instruments have already reached the stage where some individual transitions can be detected, even in weak plasmas. Where the spectrum is crowded with emission lines from multiple elements, ionization levels, and transitions, spectral modeling is performed in order to estimate the contribution from each. The goal of this paper is to provide examples of interesting atomic physics occurring in our galaxy especially that in the hot component of our galaxy, highlight some areas where new atomic calculations and measurements are needed, and explain how astrophysical atomic transitions are observed.

  4. Mechanisms of Radiation-Induced Degradation of CFCl3 and CF2Cl2 in Noble-Gas Matrixes: An Evidence for "Hot" Ionic Channels in the Solid Phase.

    PubMed

    Shiryaeva, Ekaterina S; Tyurin, Daniil A; Feldman, Vladimir I

    2016-10-13

    The X-ray-induced transformations of simple chlorofluorocarbons (CFCl3 and CF2Cl2) in solid noble-gas matrixes (Ne, Ar, Kr, and Xe) at 7 K were studied in order to elucidate basic mechanisms of the radiation-chemical degradation with possible implications for stratospheric and extraterrestrial ice chemistry. The decomposition of parent molecules and formation of products were monitored by FTIR spectroscopy, and the identification was supported by ab initio calculations at the CCSD(T) level. It was shown that the ionic reaction channels were predominating in most cases (except for CF2Cl2/Xe system). The primary radical cations (CFCl3(+•) and CF2Cl2(+•)) are either stabilized in matrixes or undergo fragmentation to yield the corresponding secondary cations (CFCl2(+), CCl3(+), CF2Cl(+)) and halogen atoms. The probability of fragmentation through different channels demonstrates a remarkable matrix dependence, which was explained by the effect of excess energy resulting from the exothermic positive hole transfer from matrix atoms to freon molecules. A qualitative correlation between "hot" ionic fragmentation at low temperatures and gas-phase ion energetics was found. However, dissociative electron attachment leads to formation of neutral radicals (CFCl2(•) or CF2Cl(•)) and chloride anions. One more possible way of dissociative electron attachment in the case of CF2Cl2 is formation of CF2(••) and Cl2(-•). A general scheme of the radiation-induced processes is proposed.

  5. Magma Dynamics at Mid-Ocean Ridges by Noble Gas Kinetic Fractionation: Assessment of Magmatic Ascent Rates and Mantle Composition

    NASA Astrophysics Data System (ADS)

    Paonita, A.; Martelli, M.

    2007-12-01

    Topical scientific literature on magma degassing at mid-ocean ridges more and more focuses on exsolution processes occurring under conditions that are far from thermodynamic equilibrium between bubbles and silicate melt. Indeed, the dynamics of magma ascent and decompression can be faster than that of CO2 diffusion into bubbles, in which case the diffusivity ratios among volatiles are the main control of the composition of the exsolving gas phase. We have developed a model of bubble growth in silicate melts that calculates the extent of both CO2 supersaturation and kinetic fractionation among noble gases in vesicles in relation to the decompressive rate of basaltic melts. The model predicts that, due to comparable Ar and CO2 diffusivity, magma degassing at low pressure fractionates both He/Ar and He/CO2 ratios by a similar extent, while the slower CO2 diffusion at high pressure causes early kinetic effects on Ar/CO2 ratio and dramatically changes the degassing paths. By using this tool, we have reviewed the global He-Ar-CO2 dataset of fluid inclusions in mid-ocean-ridge glasses. We display that non-equilibrium fractionations among He, Ar and CO2, driven by their different diffusivities in silicate melts, are common in most of the natural conditions of magma decompression and their signature strongly depends on pressure of degassing. The different geochemical signatures among suites of data coming from different ridge segments mainly depend on the depth of the magma chamber where the melt was stored. Moreover, variations inside a single suite emerge due to the interplay between variable ascent speed of magma and cooling rate of the emplaced lava. As a result, two data groups coming from the Pito Seamount suite (Easter Microplate East ridge), showing different degree of CO2 supersaturation and He/Ar fractionation, provide ascent rates which differ by ten folds or even more. The large variations in both the He/CO2 and Ar/CO2 ratios at almost constant He/Ar, displayed

  6. Diffusion kinetics of 3He and 21Ne in quartz and implications for cosmogenic noble gas paleothermometry

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    the relevant temperature range. When extrapolated to Earth surface temperatures and geologically relevant timescales, these results suggest that 1 mm-radius quartz grains lose significant amounts of cosmogenic 3He by diffusion at sub-zero temperatures from the low-retentivity domain over >103 yr timescales and from the high-retentivity domain over >104 yr, whereas quantitative retention of cosmogenic 21Ne occurs over >106 yr at temperatures ⩽40 °C in most cases. While these results are generally consistent with previously reported studies, they also reveal that sample-specific diffusion parameters are required for quantitative application of cosmogenic noble gas paleothermometry. The cosmogenic 3He abundance in one quartz sample with a simple Holocene exposure history and the stepwise degassing pattern of cosmogenic 3He and 21Ne from another quartz sample with a ∼1.2 Ma exposure history agree well with diffusion experiments on proton-irradiated aliquots of the same samples. For the sample with a simple Holocene exposure history, a production and diffusion model incorporating sample-specific diffusion parameters and the measured 3He abundance predicts an effective diffusion temperature consistent with the effective modern temperature at the sample location. This internal consistency demonstrates that the empirically determined, sample-specific diffusion kinetics apply to cosmogenic 3He and 21Ne in quartz in natural settings over geologic timescales.

  7. Mineralogy and noble-gas signatures of the carbonate-rich lithology of the Tagish Lake carbonaceous chondrite: evidence for an accretionary breccia

    NASA Astrophysics Data System (ADS)

    Nakamura, Tomoki; Noguchi, Takaaki; Zolensky, Michael E.; Tanaka, Masahiko

    2003-02-01

    The carbonate-rich lithology of the Tagish Lake carbonaceous chondrite was characterized by noble-gas mass spectrometry, synchrotron X-ray diffraction analysis, and transmission and scanning electron microscopy. Noble-gas analysis was performed on two samples and the results showed that primordial noble gases are abundant and solar noble gases are absent in the samples of carbonate-rich lithology. The concentrations of Ne-A2 and -E in both samples are at the maximum level observed for CI and CM chondrites, suggesting high abundances of presolar diamonds and SiC/graphite, respectively. The cosmic-ray exposure age cannot be determined precisely, because the shielding depth of our Tagish Lake samples is unknown, but the minimum exposure age was determined to be 5.5±0.7 Myr on the basis of cosmogenic 21Ne concentrations and the highest 21Ne production rate. X-ray and electron-microscopic study showed that the carbonate-rich lithology is dominated by loosely packed porous matrix that consists mainly of fine-grained saponite and ferromagenesian carbonate. The matrix contains very few chondrules, but many fine-grained clasts having angular shape with longest dimensions up to 1 mm. The clasts differ from host matrix in both texture and mineralogy. They are massive, compacted material with porosity much lower than matrix and contain abundant magnetite and a coherent intergrowth of serpentine and saponite that is rare in matrix. The presence of texturally and mineralogically distinct clasts indicates that the carbonate-rich lithology is a breccia, but the absence of solar noble gases and impact-induced deformational features in host matrix distinguish it from an asteroid regolith breccia. Our results instead indicate that it is an accretionary breccia formed by simultaneous accretion of diverse objects in a massive dust cloud. The clasts often enclose chondrules and anhydrous silicate fragments such as low-iron-manganese-enriched olivines. This observation and their highly

  8. A shear reversal nozzle for efficient gas atomization

    SciTech Connect