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1

NOBLE GASES  

EPA Science Inventory

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

2

Noble Gases  

NASA Astrophysics Data System (ADS)

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

Podosek, F. A.

2003-12-01

3

Noble gases in ureilites released by crushing  

NASA Astrophysics Data System (ADS)

Noble gases in two ureilites, Kenna and Allan Hills (ALH) 78019, were measured with two extraction methods: mechanical crushing in a vacuum and heating. Large amounts of noble gases were released by crushing, up to 26.5% of 132Xe from ALH 78019 relative to the bulk concentration. Isotopic ratios of the crush-released Ne of ALH 78019 resemble those of the trapped Ne components determined for some ureilites or terrestrial atmosphere, while the crush-released He and Ne from Kenna are mostly cosmogenic. The crush-released Xe of ALH 78019 and Kenna is similar in isotopic composition to Q gas, which indicates that the crush-released noble gases are indigenous and not caused by contamination from terrestrial atmosphere. In contrast to the similarities in isotopic composition with the bulk samples, light elements in the crush-released noble gases are depleted relative to Xe and distinct from those of each bulk sample. This depletion is prominent especially in the 20Ne/132Xe ratio of ALH 78019 and the 36Ar/132Xe ratio of Kenna. The values of measured 3He/ 21Ne for the gases released by crushing are significantly higher than those for heating-released gases. This suggests that host phases of the crush-released gases might be carbonaceous because cosmogenic Ne is produced mainly from elements with a mass number larger than Ne. Based on our optical microscopic observation, tabular-foliated graphite is the major carbon mineral in ALH 78019, while Kenna contains abundant polycrystalline graphite aggregates and diamonds along with minor foliated graphite. There are many inclusions at the edge and within the interior of olivine grains that are reduced by carbonaceous material. Gaps can be seen at the boundary between carbonaceous material and silicates. Considering these petrologic and noble gas features, we infer that possible host phases of crush-released noble gases are graphite, inclusions in reduction rims, and gaps between carbonaceous materials and silicates. The elemental ratios of noble gases released by crushing can be explained by fractionation, assuming that the starting noble gas composition is the same as that of amorphous carbon in ALH 78019. The crush-released noble gases are the minor part of trapped noble gases in ureilites but could be an important clue to the thermal history of the ureilite parent body. Further investigation is needed to identify the host phases of the crush-released noble gases.

Okazaki, R.; Nakamura, T.; Takaoka, N.; Nagao, K.

2003-05-01

4

Angular correlation studies in noble gases  

NASA Technical Reports Server (NTRS)

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

Coleman, P. G.

1990-01-01

5

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

NASA Astrophysics Data System (ADS)

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

Thonnard, N.

1995-09-01

6

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

NASA Astrophysics Data System (ADS)

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 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- and Si-nanotubes when combined with simple adsorption can result in stronger diffusive separation and nonsteady-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.

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

2004-10-01

7

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

SciTech Connect

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.

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

2004-06-14

8

Hyperpolarized noble gases as contrast agents.  

PubMed

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

Zhou, Xin

2011-01-01

9

Measuring the Isotopic Composition of Solar Wind Noble Gases  

E-print Network

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

10

Noble gases and nitrogen in Muong Nong tektites  

Microsoft Academic Search

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

S. V. S. Murty

1997-01-01

11

Noble Gases in the Chelyabinsk Meteorites  

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

12

Xenon and other noble gases in shergottites  

NASA Astrophysics Data System (ADS)

The isotopic composition of the xenon component trapped in EETA 79001's lithologies B and C has been determined, and other noble gases were measured in some samples. The Xe component was found to have light isotope ratios indistinguishable from those of the terrestrial atmosphere. The trapped component has a Xe-129/Xe-132 ratio of about 2.4, and is enhanced in Xe-134 and Xe-136 relative to the terrestrial atmosphere or the average carbonaceous chondrite. Similarities between values for Ar-40/Ar-36, Xe-129/Xe-132, and N-15/N-14 and the corresponding Martian atmospheric values suggest Martian origin of the trapped gases.

Swindle, T. D.; Caffee, M. W.; Hohenberg, C. M.

1986-06-01

13

Noble gases in Muong Nong-type tektites and their implications  

Microsoft Academic Search

We have measured the elemental abundances and isotopic compositions of noble gases in Muong Nong-type tektites from the Australasian strewn field by crushing and by total fusion of the samples. We found that the abundances of the heavy noble gases are significantly enriched in Muong Nong-type tektites compared to those in normal splash-form tektites from the same strewn field. Neon

Sayaka MIZOTE; Takuya MATSUMOTO; Jun-ichi MATSUDA; Christian KOEBERL

2003-01-01

14

Sir William Ramsay and the noble gases.  

PubMed

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

Davies, Alwyn G

2012-01-01

15

Biomedical imaging with hyperpolarized noble gases.  

PubMed

Hyperpolarized noble gases (HNGs), polarized to approximately 50% or higher, have led to major advances in magnetic resonance (MR) imaging of porous structures and air-filled cavities in human subjects, particularly the lung. By boosting the available signal to a level about 100 000 times higher than that at thermal equilibrium, air spaces that would otherwise appear as signal voids in an MR image can be revealed for structural and functional assessments. This review discusses how HNG MR imaging differs from conventional proton MR imaging, how MR pulse sequence design is affected and how the properties of gas imaging can be exploited to obtain hitherto inaccessible information in humans and animals. Current and possible future imaging techniques, and their application in the assessment of normal lung function as well as certain lung diseases, are described. PMID:25360484

Ruppert, Kai

2014-11-01

16

Photosensitive dopants for liquid noble gases  

SciTech Connect

A method of detecting radiation with an ionization detector is described comprising the steps of: dissolving a photosensitive dopant in a noble gas; liquifying the doped noble gas; placing the doped liquified noble gas in the ionization detector; introducing radiation to be detected into the ionization detector; collecting free ions in the ionization detector; and counting the free ions collected within the ionization detector.

Anderson, D.F.

1988-03-22

17

The Noble Gases in A-Level Chemistry.  

ERIC Educational Resources Information Center

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

Marchant, G. W.

1983-01-01

18

Noble gases in Muong Nong-type tektites and their implications  

NASA Astrophysics Data System (ADS)

We have measured the elemental abundances and isotopic compositions of noble gases in Muong Nong-type tektites from the Australasian strewn field by crushing and by total fusion of the samples. We found that the abundances of the heavy noble gases are significantly enriched in Muong Nong-type tektites compared to those in normal splash-form tektites from the same strewn field. Neon enrichments were also observed in the Muong Nong-type tektites, but the Ne/Ar ratios were lower than those in splash-form tektites because of the higher Ar contents in the former. The absolute concentrations of the heavy noble gases in Muong Nong-type tektites are similar to those in impact glasses. The isotopic ratios of the noble gases in Muong Nong-type tektites are mostly identical to those in air, except for the presence of radiogenic 40Ar. The obtained K-Ar ages for Muong Nong-type tektites were about 0.7 Myr, similar to ages of other Australasian tektites. The crushing experiments suggest that the noble gases in the Muong Nong-type tektites reside mostly in vesicles, although Xe was largely affected by adsorbed atmosphere after crushing. We used the partial pressure of the heavy noble gases in vesicles to estimate the barometric pressure in the vesicles of the Muong Nong-type tektites. Likely, Muong Nong-type tektites solidified at the altitude (between the surface and a maximum height of 8­30 km) lower than that for splash-form tektites.

Mizote, S.; Matsumoto, T.; Matsuda, J.; Koeberl, C.

2003-05-01

19

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

SciTech Connect

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

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

2011-10-10

20

Photosensitive dopants for liquid noble gases  

DOEpatents

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

Anderson, David F. (Wheaton, IL)

1988-01-01

21

Fullerenes: A New Carrier Phase for Noble Gases in Meteorites  

NASA Technical Reports Server (NTRS)

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

Becker, Luann

2004-01-01

22

Olivine separates from Murchison and Cold Bokkeveld - Particle tracks and noble gases  

NASA Technical Reports Server (NTRS)

Olivine separates from Murchison and Cold Bokkeveld were analyzed for particle tracks and noble gases. The matrix remaining after olivine separation was also analyzed for noble gases. The olivines from both meteorites have comparable fractions of solar-flare-irradiated grains, but the highest track densities in Murchison are an order of magnitude greater than those in Cold Bokkeveld. Solar Ne content in Murchison olivines follows this trend, being at least an order of magnitude higher than that in Cold Bokkeveld. Track gradients in Cold Bokkeveld olivines are flatter than those in Murchison or recently exposed lunar crystals. Relative to the matrix, olivine separates in both meteorites have small enrichments at the heavy and light Xe isotopes and smaller Ar-36/Ar-38 ratios. These noble-gas effects may be related to a chromite impurity in the olivine separates.

Macdougall, J. D.; Phinney, D.

1977-01-01

23

Noble gases and halogens in altered MORB and implications for seawater recycling  

NASA Astrophysics Data System (ADS)

Recent studies suggested that the heavy noble gases and halogens are significantly recycled into the mantle through the subduction zone, since a seawater derived signature has been recorded in the mantle [1,2]. However, the processes of how these elements preserve the unique elemental composition of seawater from the ocean floor to the subduction process are unknown. Thus, we propose here a study of altered oceanic crust to identify the respective major host phases of both noble gases and halogens in pre-subducted material. Ten altered MORB coming from the ODP sites 504, 896 and 1256 in the Eastern Pacific Ocean (5.9 and 15 Ma) are being studied. Noble gas isotopes and abundances have been determined using an upgraded VG5400 mass spectrometer. Halogens (Cl, Br, I) are obtained by measuring noble gases on irradiated samples using a MS1 mass spectrometer. The analyses were all obtained from in vacuo crushing release of whole rock samples. Preliminary results show Ne to Xe isotopically identical to air. 3He/4He ratios vary from 4.5±0.5 (R/RA) to MORB-like values. Heavy noble gas elemental ratios for 9 samples fall within a narrow range, with 130Xe/36Ar and 84Kr/36Ar ratios varying respectively by 10% and 30%. They range from values close to seawater (± air) to values enriched in Xe and Kr going towards mantle values [1]. One altered MORB shows 130Xe/36Kr and 84Kr/36Ar ratios respectively 2 and 5 times greater than the average of the other samples, which suggests the contribution of a sediment component in this sample. Halogen data obtained on 4 samples are in accordance with noble gases results. The Br/Cl molar ratio is constant (1.97±0.15.10-3) while the I/Cl molar ratio varies significantly by up to one order of magnitude, ranging from 1.2±0.3.10-6 to 9.9±0.8.10-6. These results are in favour of a mixing between a seawater endmember and a sediment pore fluid endmember, which remains to be identified. The measurements will be extended to gabbros and sediments forming the oceanic crust. Also, the addition of data obtained by heating to those obtained by crushing will allow us to better constrain the partitioning of both the noble gases and the halogens in pre-subducted material, the identification of the host phases, as well as the controls of the seawater noble gases interaction with the oceanic crust. [1] Holland & Ballentine (2006), Nature 441, 186-191. [2] Sumino et al. (2010), EPSL 294, 163-172.

Chavrit, D.; Burgess, R.; Weston, B.; Abbott, L.; Ballentine, C. J.; Teagle, D. A.; Droop, G.; Pawley, A. R.

2011-12-01

24

Nitrogen and light noble gases in Parsa enstatite chondrite  

NASA Technical Reports Server (NTRS)

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

Murty, S. V. S.

1993-01-01

25

Tectonic implications of radiogenic noble gases in planetary atmospheres  

NASA Astrophysics Data System (ADS)

Measurements of the quantity of noble gases in the atmospheres of the terrestrial planets and the Moon provide important constraints on the dynamics of atmosphere formation and loss. In this paper the authors are primarily concerned with the implications of long-lived radiogenic isotopes on the tectonics of planetary interiors. They focus their attention on the systematics of 4He and 40Ar that are produced by the principal heat-producing isotopes 238U, 235U, 232Th, and 40K. The efficiency of escape of these noble gas isotopes can provide insights into both transport mechanisms and internal processes.

Turcotte, D. L.; Schubert, G.

1988-04-01

26

Nitrogen and light noble gases in Shergotty  

NASA Astrophysics Data System (ADS)

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

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

1986-06-01

27

Fullerenes: An extraterrestrial carbon carrier phase for noble gases  

PubMed Central

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

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

2000-01-01

28

Preserving noble gases in a convecting mantle Helge M. Gonnermann1  

E-print Network

of a processed and out- gassed lower-mantle source, residues of mantle melting10,11 , depleted in uranium and mixing of noble-gas-depleted slabs dilutes the concentrations of noble gases in the mantle, thereby melt, which forms the ocean crust and leaves the residual mantle severely depleted of noble gases

Mukhopadhyay, Sujoy

29

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

NASA Astrophysics Data System (ADS)

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

Yang, J.; Anders, E.

1982-06-01

30

Recent Experimental Advances to Determine (noble) Gases in Waters  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

31

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

NASA Astrophysics Data System (ADS)

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

Hiyagon, H.; Kennedy, B. M.

1992-04-01

32

Howardite Noble Gases as Indicators of Asteroid Surface Processing  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

33

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

NASA Astrophysics Data System (ADS)

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

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

1993-07-01

34

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

NASA Astrophysics Data System (ADS)

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

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

1999-01-01

35

Noble gases and radiocarbon in natural gas hydrates  

NASA Astrophysics Data System (ADS)

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

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

2002-05-01

36

Solubilities of nitrogen and noble gases in basalt melt  

NASA Astrophysics Data System (ADS)

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

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

37

Solubilities of nitrogen and noble gases in basalt melt  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

38

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

NASA Astrophysics Data System (ADS)

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

Nakamura, Tomoki; Nagao, Keisuke; Takaoka, Nobuo

1999-01-01

39

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

NASA Technical Reports Server (NTRS)

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

Lancet, M. S.; Anders, E.

1973-01-01

40

Chemical composition of Titan's lakes and noble gases sequestration  

NASA Astrophysics Data System (ADS)

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

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

2010-04-01

41

Noble gases and cosmogenic radionuclides in the Eltanin Pacific meteorite  

SciTech Connect

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

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

2000-01-14

42

Noble gases in the howardites Bholghati and Kapoeta  

NASA Technical Reports Server (NTRS)

Analyses of noble gases in whole rock samples of the howardites Bholghati and Kapoeta and grain-size separates of Kapoeta yield evidence for excesses of the Xe isotopes Xe-129 , Xe-131, Xe-132, Xe-134, and Xe-136 in a low-temperture component, similar to lunar excess fission Xe. Such a component may be able to provide chronometric information if the relative abundances of radioactive progenitors (I-129, Pu-244, and U-238) can be determined, but the isotopic spectra obtained are not sufficiently precise to do so. Eucritic clast BH-5 in Bholghati contains Xe produced in situ by the decay of Pu-244. Calculated fission Xe retention ages are 30-70 Ma after the formation of the solar system, consistent with the apparent presence of Sm-146 decay products. Both the clast and the matrix of Bholghati have K-Ar ages of about 2 Ga, suggesting a common thermal event at least that recently.

Swindle, T. D.; Hohenberg, C. M.; Nickols, R. H.; Olinger, C.; Garrison, D. H.; Goswami, J. N.

1990-01-01

43

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

NASA Astrophysics Data System (ADS)

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

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

1993-07-01

44

Subduction zone fluxes of halogens and noble gases in seafloor and forearc serpentinites  

NASA Astrophysics Data System (ADS)

Serpentinites form by hydration of ultramafic lithologies in a range of seafloor and shallow subduction zone settings. Serpentinites are recognised as major reservoirs of fluid mobile elements and H2O in subducting oceanic lithosphere, and together with forearc serpentinites formed in the mantle wedge, provide critical information about shallow-level volatile fluxes during subduction. The current study provides new Cl, as well as the first comprehensive Br, I and noble gas analyses reported for seafloor and forearc chrysotile-lizardite serpentinites. The samples were recovered from IODP drilling campaigns of mid-ocean ridge, passive margin and forearc settings (n=17), and ophiolites in the Italian Alps and Apennines (n=10). The aims of this study were to determine the compositional variability of noble gases and halogens in serpentinites entering subduction zones and evaluate the efficiency of gas loss during the early stages of serpentinite subduction. The chrysotile-lizardite serpentinites and serpentised peridotites contain 43-2300 ppm Cl and 3×10-13-2×10-11 mol g-136Ar, with the concentrations of these elements broadly related to the estimated degree of serpentinisation. The serpentinites have extremely variable Br/Cl and I/Cl ratios with many samples preserving compositions similar to organic-rich sedimentary marine pore fluids. Serpentinites from the Marianas Forearc have very high I concentrations of up to 45 ppm I and I/Cl ratios of ˜14,000 times the seawater value that is even higher than the maximum I/Cl enrichment observed in sedimentary marine pore fluids. The serpentinites have 130Xe/36Ar and 84Kr/36Ar ratios that are mostly close to or above seawater values, and 20Ne/36Ar ratios that range from seawater to lower values. The serpentinites contain <10-270 ppm K and, irrespective of age (0 Ma to ˜160 Ma), are characterised by 40Ar/36Ar ratios of 300-340 that are slightly higher than the seawater value of 296, thus indicating the presence of minor excess 40Ar*. Three of six serpentinites analysed for helium also have measurable excess 4He contents that cannot be explained by in situ production. The data show that serpentinites trap noble gases and halogens that originate from seawater, organic matter and diverse crustal lithologies. Combined with previous analyses of metamorphosed serpentinites, the new data suggest that approximately 60-70% of the 36Ar entering subduction zones in serpentinites is lost from chrysotile and/or antigorite and could potentially escape through the forearc. An additional, ˜20-30% of the 36Ar entering subduction zones in serpentinites is lost during antigorite breakdown and may be cycled through the arc or back-arc, and ˜1-10% of the 36Ar entering subduction zones in serpentinites may be subducted into the deeper mantle. The data demonstrate decoupling of noble gases, halogens and water during subduction and suggest that subduction-zone fluid fluxes can produce especially high concentrations of noble gases and iodine in newly formed forearc serpentinites. The distinctive I/Cl enrichment of forearc serpentinites suggest that halogen abundance ratios provide a plausible means for inferring the geotectonic setting of serpentinisation in ophiolite samples. The exceptional Cl, Br, I and noble gas concentrations of serpentinites, the potential subduction of the forearc serpentinites and the stability of serpentine minerals to mantle depths of >200 km, imply that serpentinites could dominate the deep recycling budgets of both the heavy halogens and atmospheric noble gases.

Kendrick, Mark A.; Honda, Masahiko; Pettke, Thomas; Scambelluri, Marco; Phillips, David; Giuliani, Andrea

2013-03-01

45

Using noble gases to investigate mountain-front recharge  

USGS Publications Warehouse

Mountain-front recharge is a major component of recharge to inter-mountain basin-fill aquifers. The two components of mountain-front recharge are (1) subsurface inflow from the mountain block (subsurface inflow), and (2) infiltration from perennial and ephemeral streams near the mountain front (stream seepage). The magnitude of subsurface inflow is of central importance in source protection planning for basin-fill aquifers and in some water rights disputes, yet existing estimates carry large uncertainties. Stable isotope ratios can indicate the magnitude of mountain-front recharge relative to other components, but are generally incapable of distinguishing subsurface inflow from stream seepage. Noble gases provide an effective tool for determining the relative significance of subsurface inflow, specifically. Dissolved noble gas concentrations allow for the determination of recharge temperature, which is correlated with recharge elevation. The nature of this correlation cannot be assumed, however, and must be derived for the study area. The method is applied to the Salt Lake Valley Principal Aquifer in northern Utah to demonstrate its utility. Samples from 16 springs and mine tunnels in the adjacent Wasatch Mountains indicate that recharge temperature decreases with elevation at about the same rate as the mean annual air temperature, but is on average about 2??C cooler. Samples from 27 valley production wells yield recharge elevations ranging from the valley elevation (about 1500 m) to mid-mountain elevation (about 2500 m). Only six of the wells have recharge elevations less than 1800 m. Recharge elevations consistently greater than 2000 m in the southeastern part of the basin indicate that subsurface inflow constitutes most of the total recharge in this area. ?? 2003 Published by Elsevier Science B.V.

Manning, A.H.; Solomon, D.K.

2003-01-01

46

Atom-atom excitation and ionization in shock waves of the noble gases  

Microsoft Academic Search

Rate coefficients for electron production in the relaxation zone behind the shock front in the noble gases have been calculated on the basis of a simplified model using generalized cross sections for atom-atom excitation and ionization of noble gas atoms.

H. W. Drawin; F. Emard

1973-01-01

47

Noble gases identify the mechanisms of fugitive gas contamination in drinking-water wells overlying the  

E-print Network

12, 2014 (received for review November 27, 2013) Horizontal drilling and hydraulic fracturing have triggered by horizontal drilling or hydraulic fracturing. noble gas geochemistry | groundwater contamination from coal toward hydrocarbon gases produced from unconventional resources (1, 2). Horizontal drilling

Jackson, Robert B.

48

Interstellar grains in meteorites: III. Graphite and its noble gases  

NASA Astrophysics Data System (ADS)

Four density fractions of interstellar graphite were analyzed for isotopically anomalous noble gases by stepped heating. As in SiC, the dominant components show the signature of the s-process and apparently come from AGB- (Asymptotic Giant Branch) stars of 1-3 M?. But graphite seems to come from a broader range of stars and conditions, comprising at least three and perhaps all four known sources of carbon stardust. Two extreme types of Kr?S are present, having high or low( Kr86/Kr82) s ratio and occurring in high- or low-density graphite, respectively. [ ( Kr86/Kr82) s = 4.8 in the fraction of 2.15-2.20 g/mL and ?0.5 in fractions of ?2.15 g/mL]. These imply two different kinds of AGB-stars, with mean neutron exposures of ?0.55 mb -1 and ?0.07 mb -1 . In addition to neon from AGB-star He-shells with its characteristic Ne20/Ne22 ? 0.09, all graphite fractions also contain monoisotopic Ne 22 from the decay of Na 22 ( t 1/2 = 2.58a ). This suggests the presence of material from novae and supernovae. In contrast to the differences in isotopic ratios, the elemental ratios of the anomalous gases resemble those of SiC, with a generally close match to AGB-star He-shells. But Ne is low by 10-100x, presumably due to diffusion loss.

Amari, Sachiko; Lewis, Roy S.; Anders, Edward

1995-04-01

49

Underground Nuclear Explosions and Release of Radioactive Noble Gases  

NASA Astrophysics Data System (ADS)

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

Dubasov, Yuri V.

2010-05-01

50

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

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

51

Depth Profiles of Cosmogenic Noble Gases in the Chondrite Knyahinya  

NASA Astrophysics Data System (ADS)

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

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

1993-07-01

52

The recycling efficiency of water and noble gases to the mantle  

NASA Astrophysics Data System (ADS)

Constraints on the long-term cycling of volatiles between the mantle and exosphere are crucial to understanding mantle rheology, the structure and style of mantle convection, and the volatile budget of our planet. Recent studies suggest that water and noble gases (Ar, Kr, Xe) may be transported together into the mantle. In light of uncertainties in the initial hydration state of subducting slabs, magma production rates and mantle source water contents, we used a Monte Carlo simulation of the deep Earth water cycle to set limits on long-term mantle regassing. The simulation is constrained by reconstructions of Phanerozoic sea level change. We find that previous estimates of both the flux of water into subduction zones and the return flux beyond depths of magma generation are frequently too large to reflect long-term water cycling. Our results suggest a limited extent of serpentinization in subducting lithospheric mantle. We find an average return flux of 1.4-3.0 x 1013 moles/yr, corresponding to 2-5% serpentinization in 10 km of lithospheric mantle. Our estimates of the return flux of water past arcs are up to 7 times lower than previously suggested and imply bulk slab water contents of 280- 400 ppm. Convective stirring and assimilation of recycled slabs with these water contents could account for the MORB source water. Furthermore, the MORB source may be getting wetter as water concentrations in the slab are higher than the MORB source concentrations of ~50 - 250 ppm. On the other hand, the water content of the high 3He/4He OIBs source is 750 ppm, suggesting that not all of the water in the OIB source has been recycled, i.e. a juvenile contribution is required. The recycling of water associated with serpentine has implications for the recycling of heavy noble gases (Ar, Kr, Xe) back into the mantle as serpentines may host considerable amounts of dissolved noble gases. Since the noble gases are important in understanding mantle dynamics, constraining the recycling efficiency of the noble gases is crucial. For example, 129Xe/130Xe in OIBs are closer to the atmospheric ratio than MORBs, which could reflect a higher proportion of recycled Xe in the OIB source or the sampling of an ancient (>4.45 Ga) less degassed reservoir. The reservoir age is from 129I, which produces 129Xe and became extinct at 4.45 Ga. Our high-precision Xe measurements in MORBs and OIBs indicate that at most ~80-90% of the Xe in the MORB source mantle could be attributed to recycled atmospheric Xe. Furthermore, the measurements indicate that OIBs do not have a higher proportion of recycled atmospheric Xe and thus the closer to atmospheric 129Xe/130Xe is not solely due to recycling. We will use these constraints on the amount of recycled Xe in to further refine water recycling rates. The observation that the differences in the Xe isotopic composition of MORBs and OIBs cannot be attributed solely to recycling has implications for Earth structure and early Earth processes. It requires that the closer to atmospheric 129Xe/130Xe in OIBs reflects a less degassed reservoir that evolved with a lower I/Xe ratio than the MORB source. Differences in the degree of outgassing between MORB and OIB sources must be established by 4.45 Ga and subsequent mixing between the two reservoirs must be limited. If OIBs are derived from the large low shear wave velocity provinces (LLSVPs), the Xe data require these features to be older than 4.45 Ga.

Mukhopadhyay, S.; Parai, R.; Peto, M. K.; Tucker, J.

2012-12-01

53

Noble Gases in Stratospheric Dust Particles: Confirmation of Extraterrestrial Origin  

Microsoft Academic Search

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

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

1981-01-01

54

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

NASA Technical Reports Server (NTRS)

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

Becker, Richard H.; Pepin, Robert O.

1994-01-01

55

Methane activation using noble gases in a dielectric barrier discharge reactor  

SciTech Connect

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.

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

2013-08-15

56

Method and apparatus for measuring purity of noble gases  

DOEpatents

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

Austin, Robert (Largo, FL)

2008-04-01

57

On the origin of noble gases in mantle plumes.  

PubMed

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

Coltice, Nicolas; Ricard, Yanick

2002-11-15

58

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

PubMed

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

Caffee; Hudson; Velsko; Huss; Alexander; Chivas

1999-09-24

59

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

E-print Network

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

Paris-Sud XI, Université de

60

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

NASA Technical Reports Server (NTRS)

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

Pohl, Robert O.

2003-01-01

61

Relative Responses of Noble Gases Using a Pulsed Discharge Helium Photoionization Detector: Theoretical Calculation and Experimental Determination  

Microsoft Academic Search

The relative response factors(RRFs) for noble gas(Ng) were determined on a pulsed discharge helium photoionization detector. Using ab initio method, the atomic orbitals of noble gas were calculated and used to determine the number of ionizable electrons on the basis of the continuous emission of He2. The molar responses of noble gases is well correlated with the number of ionizable

Hai-tao ZHANG; Di WU; Li-xing ZHANG

2008-01-01

62

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

63

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

Microsoft Academic Search

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

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

1989-01-01

64

The contribution by interplanetary dust to noble gases in the atmosphere of Mars  

NASA Astrophysics Data System (ADS)

Interplanetary dust particles accumulate significant concentrations of noble gases, implanted by the solar wind and solar energetic particles, while they are in space. When these dust particles enter the atmosphere of a planet they are heated and decelerated, depositing some of the implanted noble gases directly into the atmosphere and, if the particle survives atmospheric entry, emplacing the remainder on the surface of the planet, where it can be released by particle decomposition or by episodic surface heating. Because of the low mass of the atmosphere of Mars, compared to the atmospheres of Venus and Earth, the atmosphere of Mars is more severely influenced by the addition of noble gases by interplanetary dust. The contribution of noble gases to Mars has been modeled using estimates of the interplanetary dust flux at Mars and measurements of the noble gas contents of interplanetary dust collected from the atmosphere of the Earth. Over the past 3.6 b.y., interplanetary dust particles have contributed quantities of 3He, 4He, 20Ne and 22Ne comparable to the current total atmospheric inventories of these isotopes. In the present era, the rates of addition of 3He, 20Ne, 22Ne, 36Ar, and 38Ar to the atmosphere of Mars by interplanetary dust range from about 2% to 20% of the modeled rates of addition by planetary outgassing [Pepin, 1994; Krasnopolsky and Gladstone, 1996], and the isotopic compositions of the He and Ne added by interplanetary dust are distinctly different from those assumed for planetary outgassing: 3He/4He~2.8×10-4 in the interplanetary dust [Nier and Schlutter, 1992] versus almost pure 4He for outgassing of U and Th decay products, and 20Ne/22Ne~11.8 in the interplanetary dust [Nier, 1994] versus 20Ne/22Ne=13.7 assumed for planetary outgassing in Pepin's [1994] model. Since the actual outgassing rate of Mars in the present era is not well constrained by observations, the contributions of Ne and Ar to the atmosphere of Mars by the interplanetary dust must serve, at least, as a lower limit on the current sources of these noble gases.

Flynn, G. J.

65

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

SciTech Connect

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

Goodson, Boyd M.

1999-12-01

66

Noble gases released by vacuum crushing of EETA 79001 glass  

NASA Astrophysics Data System (ADS)

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

Wiens, R. C.

1988-12-01

67

Cosmogenic 10Be and Noble Gases in Diogenites  

NASA Astrophysics Data System (ADS)

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

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

1993-07-01

68

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

69

Use of Stable Noble Gases as a Predictor of Reactor Fuel Type and Exposure  

SciTech Connect

Ensuring spent reactor fuel is not produced to provide weapons-grade plutonium is becoming a major concern as many countries resort to nuclear power as a solution to their energy problems. Proposed solutions range from the development of proliferation resistant fuel to continuous monitoring of the fuel. This paper discusses the use of the stable isotopes of the fissiogenic noble gases, xenon and krypton, for determining the burnup characteristics, fuel type, and the reactor type of the fuel from which the sample was obtained. The gases would be collected on-stack as the fuel is reprocessed, and thus confirm that the fuel is as declared.

Fearey, B.L.; Charlton, W.S.; Perry, R.T.; Poths, J.; Wilson, W.B.; Hemberger, P.H.; Nakhleh, C.W.; Stanbro, W.D.

1999-08-30

70

Slab-Derived Noble Gases Preserved in Wedge Mantle Peridotite From the Sanbagawa Belt, Shikoku, Japan  

NASA Astrophysics Data System (ADS)

Subduction volcanism is generally considered to form a 'subduction barrier' that efficiently recycles volatile components contained in subducted slabs back to the Earth's surface. Water-rich fluids released from subducting slabs play an important role in this volatile circulation. However, noble gases in the fluids are not well investigated. The Higashi-akaishi peridotite body in the Sanbagawa metamorphic belt, southwest Japan, is a possibly unique example of a km-scale sliver of a former mantle wedge exhumed from depths of at least 100 km. The body mainly consists of dunite with minor amounts of garnet-bearing rocks. Penetrative porphyroclastic microstructure in the dunite is associated with the development of olivine LPO patterns implying hydrous and high-stress conditions. Serpentine dominated micro-inclusions in the porphyroclastic olivine grains are regarded as relics of former water-rich inclusions developed in the wedge mantle above a subducting slab. Thus, it is expected that these micro-inclusions should preserve noble gas characteristics of slab-derived fluids and measurements of their compositions could provide important constraints on geochemical models of subduction zones. To extract noble gases from the micro-inclusions we first step heated the samples up to 800°C, above the breakdown temperature of serpentine minerals, before crushing them in vacuo. This treatment ensures both platy antigorite matrix grains and cross-cutting lizardite veins that formed after the micro-inclusions broke down during the heating and their contained noble gases were almost entirely released at this stage. In contrast, micro-inclusions are enclosed in thermally stable "capsules" of olivine and their noble gases should be dominantly released during the subsequent crushing. The determined isotopic characteristics of noble gases in the micro-inclusions are as follows. (1) {}3He/{}4He ratios of about 2 Ra representing a mixture of mantle and radiogenic He. (2) {}40Ar/{}36Ar ratios up to 440 that are close to atmospheric ratios with a small contribution of mantle and/or radiogenic Ar. The mantle He and atmospheric Ar should be an intrinsic feature of the micro-inclusions. This implies that Ar in the wedge mantle was heavily contaminated by an atmospheric component derived from the subducting slab. Ar analyses of neutron-irradiated samples revealed insignificant contribution of in situ radiogenic {}40Ar accumulated after the formation of micro-inclusions that predates cooling ages of the Sanbagawa metamorphism (c. 76-94 Ma). However, it remains uncertain whether slab-derived He (possibly crust-like, enriched in radiogenic He) is contained in the micro-inclusions, due to relatively poor constraints on the amount of in situ radiogenic He production. The noble gas isotopic features of the micro-inclusions are similar to those of arc volcanic gases and rocks. This implies that the Higashi-akaishi peridotite body has frozen in and preserved an inferred but previously unseen part of the recycling process whereby noble gases (and probably other volatiles) are injected into the wedge mantle just above the subducting slab before being recycled back to the atmosphere via arc volcanism.

Sumino, H.; Mizukami, T.; Wallis, S. R.

2005-12-01

71

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

USGS Publications Warehouse

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

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

1988-01-01

72

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

NASA Technical Reports Server (NTRS)

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

Swindle, T. D.

1988-01-01

73

Radiative precursors driven by converging blast waves in noble gases  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

74

Radiative precursors driven by converging blast waves in noble gases  

SciTech Connect

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

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

2014-03-15

75

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

NASA Astrophysics Data System (ADS)

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

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

1982-06-01

76

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

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

77

Noble Gases Released by Crushing from Happy Canyon E-Chondrite  

NASA Astrophysics Data System (ADS)

The Happy Canyon (HC) enstatite (E-) chondrite is an impact-melt breccia formed probably from the EL-chondrite parent body. We analyzed it (weighing 0.310 g) for crush-released noble gases. Considerable amounts of trapped Ar, Kr and Xe, and radiogenic 129Xe were released. Twelve percent of bulk Xe appeared by triplicate steps of crushing; one step of crushing consists of 100x pounding. The amounts of gases released at each step of crushing are essentially constant, suggesting that greater portions of trapped gases could be released by more extensive crushing. The isotopic ratio of Xe is approximately solar except for 129Xe. The 129Xe/132Xe ratio is 3.8, being constant at each step. Elemental ratios are largely fractionated compared to the bulk composition: 36Ar/84Kr/132Xe = 31.9/0.68/1.

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

1996-03-01

78

Implantation of high concentration noble gases in cubic zirconia and silicon carbide: A contrasted radiation tolerance  

NASA Astrophysics Data System (ADS)

The modifications of the microstructure of yttria-stabilized cubic zirconia and silicon carbide single crystals implanted with high concentrations of noble gas ions and subsequently annealed at high temperature were characterized using RBS/C, XRD and TEM. It is found that the annealing behavior is strongly dependent on both the material and the implanted noble gases. Ar-implanted yttria-stabilized zirconia shows no significant microstructural modification upon annealing at 800 °C, e.g. dislocations are still present and the size of the Ar bubbles does not evolve. This is in strong contrast with previous observations on helium-implanted zirconia, where the formation of bubbles and elongated fractures were observed. In the case of SiC, thermal annealing at 1000 °C shows an enhanced damage recovery when He is implanted as compared to Ar implantation and the recrystallization of the matrix is accompanied with the release of noble gas atoms. This difference can be ascribed to different atomic radii, and thus mobility of implanted species.

Veli?a, Gihan; Debelle, Aurélien; Thomé, Lionel; Mylonas, Stamatis; Vincent, Laetitia; Boulle, Alexandre; Jagielski, Jacek; Pantelica, Dan

2014-08-01

79

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

80

A theoretical study of the cohesion of noble gases on graphite  

NASA Astrophysics Data System (ADS)

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

Bichoutskaia, Elena; Pyper, Nicholas C.

2008-01-01

81

Noble Gas Analysis of the Julesburg L3.6, Tulia H4, Y-86789 Thermally Metamorphosed CM, and Allende CV3 Chondrites by Crushing Method  

Microsoft Academic Search

We analyzed noble gases of the Julesburg L3.6, Tulia H4, Y-86789 thermally metamorphosed CM, and Allende CV3 chondrites by the stepped crushing method. All samples have released light noble gases with meteoritic isotopic compositions and heavy noble gases which are contaminated with air to various extents. Total amounts of crash-released noble gases of the four meteorites are estimated to be

D. Fukuda; T. Nakamura; N. Takaoka; K. Nagao

1996-01-01

82

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

NASA Astrophysics Data System (ADS)

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

Wacker, J. F.

1989-06-01

83

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

NASA Technical Reports Server (NTRS)

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

Wacker, John F.

1989-01-01

84

Shock Compression of Liquid Noble Gases to Multi-Mbar Pressures  

NASA Astrophysics Data System (ADS)

The high pressure -- high temperature behavior of noble gases is of considerable interest because of their use in z-pinch liners for fusion studies and for understanding astrophysical and planetary evolution. However, our understanding of the equation of state (EOS) of the noble gases at extreme conditions is limited. A prime example of this is the liquid xenon Hugoniot. Previous EOS models rapidly diverged on the Hugoniot above 1 Mbar because of differences in the treatment of the electronic contribution to the free energy. Similar divergences are observed for krypton EOS. Combining shock compression experiments and density functional theory (DFT) simulations, we can determine the thermo-physical behavior of matter under extreme conditions. The experimental and DFT results have been instrumental to recent developments in planetary astrophysics and inertial confinement fusion. Shock compression experiments are performed using Sandia's Z-Accelerator to determine the Hugoniot of liquid xenon and krypton in the Mbar regime. Under strong pressure, krypton and xenon undergo an insulator to metal transition. In the metallic state, the shock front becomes reflective allowing for a direct measurement of the sample's shock velocity using laser interferometry. The Hugoniot state is determined using a Monte Carlo analysis method that accounts for systematic error in the standards and for correlations. DFT simulations at these extreme conditions show good agreement with the experimental data -- demonstrating the attention to detail required for dealing with elements with relativistic core states and d-state electrons. The results from shock compression experiments and DFT simulations are presented for liquid xenon to 840 GPa and for liquid krypton to 800 GPa, decidedly increasing the range of known behavior of both gases. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U. S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Root, Seth

2011-11-01

85

Noble gases in South Indian carbonatites: Trapped and in situ components  

NASA Astrophysics Data System (ADS)

We have studied noble gases in carbonates and apatites from three carbonatites of South India, namely Hogenakal (2400 Ma), Sevattur (770 Ma) and Khambamettuu (523 Ma) by vacuum crushing. Apatite has also been analysed by pyrolysis. Vacuum crushing mostly releases the trapped gas components. The ratios 21Ne/ 20Ne, 22Ne/ 20Ne and 40Ar/ 36Ar increase with progressive crushing due to preservation of different composition gases in smaller inclusions released in later steps. This heterogeneity of isotopic composition of fluid inclusions is a consequence of the involvement of magmas carrying different noble gas signatures. The inclusions with lower ratios suggest the presence of a subducted atmospheric component, while the higher 21Ne/ 20Ne, 22Ne/ 20Ne and 40Ar/ 36Ar can be attributed to the presence of an enriched lithospheric mantle component. In addition, very minor trapped gases from less degassed, deeper mantle may also be present but overprinted by lithospheric and/or nucleogenic components. We propose that these carbonatites were generated only in an advanced stage of magmatism when this lithospheric component overwhelmed any contribution from the deeper mantle source. The lithospheric mantle underwent enrichment during an ancient subduction process through mantle metasomatism manifested in nucleogenic/radiogenic isotopic ratios of 21Ne/ 20Ne, 22Ne/ 20Ne and 40Ar/ 36Ar. The apatites analysed by pyrolysis clearly show nucleogenic 21Ne from 18O(?,n) reaction. We have demonstrated the potential of using U,Th- 21Ne systematics as a thermo-chronometer in conjunction with the established U,Th- 4He and U- 136Xe clocks. While for Hogenakal, the U,Th- 21Ne age of 845 ± 127 Ma is in agreement with the age of emplacement of other adjacent younger carbonatites, syenites and alkali granites, for the Sevattur apatite (738 ± 111 Ma) it indicates the crystallisation age.

Murty, S. V. S.; Basu, S.; Kumar, Anil

2007-04-01

86

Effects of traces of molecular gases (hydrogen, nitrogen) in glow discharges in noble gases  

NASA Astrophysics Data System (ADS)

The "Grimm" type of low pressure glow discharge source, introduced some forty years ago, has proved to be a versatile analytical source. A flat sample is used as the cathode and placed about 0.2mm away from the end of a hollow tubular anode leading to an obstructed discharge. When the source was first developed, it was used for the direct analysis of solid metallic samples by optical emission spectroscopy (OES), normally with argon as the plasma gas; it was soon found that, using suitable electrical parameters, the cathode material was sputtered uniformly from a circular crater of diameter equal to that of the tubular anode, so that the technique could be used for compositional depth profile analysis (CDPA). Over the years the capability and applications of the technique have steadily increased. The use of rf powered discharges now permits the analysis of non-conducting layers and samples; improved instrumental design now allows CDPA of ever thinner layers (e.g. resolution of layers 5 nm thick in multilayer stacks is possible). For the original bulk material application, pre-sputtering could be used to remove any surface contamination but for CDPA, analysis must start immediately the discharge is ignited, so that any surface contamination can introduce molecular gases into the plasma gas and have significant analytical consequences, especially for very thin layers; in addition, many types of samples now analysed contain molecular gases as components (either as occluded gas, or e.g. as a nitride or oxide), and this gas enters the discharge when the sample is sputtered. It is therefore important to investigate the effect of such foreign gases on the discharge, in particular on the spectral intensities and hence the analytical results. The presentation will concentrate mainly on the effect of hydrogen in argon discharges, in the concentration range 0-2 % v/v but other gas mixtures (e.g. Ar/N_2, Ne/H_2) will be considered for comparison. In general, the introduction of molecular gases can change the discharge impedance, alter the sputtering rate and crater profile and cause changes in the absolute and relative intensities of lines in both the atomic and ionic spectra of the sample element and the plasma gas. The authors wish to acknowledge financial support from EC funded Analytical Glow Discharge Research Training Network GLADNET, contract no. MRTN-CT-2006-035459. P. Smid thanks the Deutsche Forschungsgemeinschaft (Ref 436 TSE 17/7/06) for support while carrying out experiments at IFW Dresden.

Steers, E. B. M.; Smid, P.; Hoffmann, V.

2008-07-01

87

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

88

Analysis of salt effects on solubility of noble gases in water using the reference interaction site model theory  

Microsoft Academic Search

We have developed robust and very efficient algorithms for solving the reference interaction site model (RISM) equations for salt solutions in the bulk and near a solute atom of noble gases. The theory of dielectric consistency recently developed for solutions at finite salt concentrations is employed in the formalism. The change in water structure in the bulk caused by addition

Masahiro Kinoshita; Fumio Hirata

1997-01-01

89

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

NASA Astrophysics Data System (ADS)

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

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

1985-04-01

90

Evidence for high saturation of porous amorphous carbon films by noble gases  

NASA Astrophysics Data System (ADS)

Results of the electron diffraction study of Kr and Xe deposits on amorphous porous carbon substrates are reported. We have observed mixtures of crystallites typical of condensates formed at such substrates at low deposition temperatures. However, in the warming process at temperatures about three to five degrees below the sublimation point characteristic of flat substrates, the diffraction patterns demonstrate that large crystallites gradually disappear and a highly disordered matter forms. Such transformed samples are kept inside substrates several dozens degrees above the sublimation points which are typical of these substances on flat (e.g., metallic) substrates. We ascribe these features to specificity of composites formed from noble gases strongly bonded inside porous carbon matrices due to capillary filling at temperatures close to the sublimation points.

Krainyukova, N. V.

2009-04-01

91

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

92

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

PubMed

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

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

2013-08-01

93

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

94

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

SciTech Connect

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

Bourg, I.C.; Sposito, G.

2007-05-25

95

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

EPA Science Inventory

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

96

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

97

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

PubMed

We have performed relativistic calculations of single and double core 1s hole states of the noble gas atoms in order to explore the relativistic corrections and their additivity to the ionization potentials. Our study unravels the interplay of progression of relaxation, dominating in the single and double ionization potentials of the light elements, versus relativistic one-electron effects and quantum electrodynamic effects, which dominate toward the heavy end. The degree of direct relative additivity of the relativistic corrections for the single electron ionization potentials to the double electron ionization potentials is found to gradually improve toward the heavy elements. The Dirac-Coulomb Hamiltonian is found to predict a scaling ratio of ?4 for the relaxation induced relativistic energies between double and single ionization. Z-scaling of the computed quantities were obtained by fitting to power law. The effects of nuclear size and form were also investigated and found to be small. The results indicate that accurate predictions of double core hole ionization potentials can now be made for elements across the full periodic table. PMID:21823703

Niskanen, J; Norman, P; Aksela, H; Agren, H

2011-08-01

98

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

SciTech Connect

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

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

2011-08-07

99

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

NASA Technical Reports Server (NTRS)

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

Garrison, Daniel H.; Bogard, Donald D.

1997-01-01

100

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

SciTech Connect

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

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

2013-11-14

101

Sensitivity and resolution in 3D NMR microscopy of the lung with hyperpolarized noble gases.  

PubMed

Three-dimensional magnetic resonance images of the guinea pig lung were acquired in vivo using hyperpolarized (HP) noble gases and radial projection encoding (PE). Results obtained with 3He (voxel size 17 microl) demonstrated high image quality showing airway structure down to the 5th or 6th generations. Signal-to-noise ratios (SNRs) of 129Xe images (voxel size 40 microl) were lower by about 1 order of magnitude as a consequence of the smaller gyromagnetic ratio, a more rapid relaxation in the gas reservoir, and lower polarization and isotope abundance. Comparison between experimentally obtained SNRs and results from calculations based on a model that accounts for the three-dimensional PE acquisition scheme and the non-equilibrium situation in HP gas imaging yielded excellent agreement for small flip angles. A theoretical examination of the potential resolution in HP gas MR microscopy of the lungs suggests that in vivo visualization of alveolar clusters distal to respiratory bronchioles may be possible. PMID:10332857

Möller, H E; Chen, X J; Chawla, M S; Cofer, G P; Driehuys, B; Hedlund, L W; Suddarth, S A; Johnson, G A

1999-04-01

102

Noble gases in individual chondrules of the Allende CV3 chondrite  

NASA Astrophysics Data System (ADS)

We analyzed noble gases in nine individual chondrules, an assemblage of small chondrules, and four whole-rock samples of the Allende CV3 chondrite. Major elements were also determined for five chondrules. The cosmic ray exposure ages are calculated from cosmogenic 3He to be 5.17 ± 0.38 and 5.15 ± 0.25 Myr for the averages of the chondrules and whole rocks, respectively, showing no significant pre-exposure evidence for the studied chondrules. Large amounts of 36Ar, 80,82Kr, and 128Xe produced by neutron capture are observed in most samples; the abundances of these nuclides are correlated among the samples. The epithermal neutron flux and neutron slowing down density are calculated based on [80Kr]n, from which a sample depth of about 30 cm can be calculated. The measured chondrules contain variable amounts of radiogenic 129Xe. The abundance ratios of radiogenic 129Xe to neutron capture-produced 128Xe are rather constant among the studied chondrules; four chondrules give more precise ratios at the high-temperature fractions, ranging from 1920 ± 80 to 2280 ± 140, which corresponds to a time difference of 3.9 ± 2.4 Myr. It is noticeable that most chondrules also contain 244Pu-derived fission Xe. The average 244Pu/238U ratio for nine chondrules is 0.0069 ± 0.0018, which agrees well with the preferred ratio reported for chondrites.

Miura, Yayoi N.; Nagao, Keisuke; Kimura, Makoto

2014-06-01

103

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

NASA Astrophysics Data System (ADS)

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

Pressyanov, Dobromir S.

2013-07-01

104

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

NASA Astrophysics Data System (ADS)

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

Glein, Christopher R.

2015-04-01

105

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

106

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

PubMed Central

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

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

2014-01-01

107

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

PubMed

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

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

2014-09-30

108

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

USGS Publications Warehouse

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

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

1993-01-01

109

Extraction of the neutron-electron scattering length from the neutron diffraction data measured on noble gases  

NASA Astrophysics Data System (ADS)

A new method of extracting the neutron-electron scattering length b, which is directly connected with the fundamental physical value of neutron mean squared charge radius, from the slow neutron diffraction on noble gases was developed and verified by the analysis of literature data on structure factors for gaseous Kr and 36Ar and for liquid Kr. Different variants of analysis of these experimental data allow us to obtain b value with the statistical accuracy of 10-20%, but in some of them the real possibility for the accessible accuracy no worse than 2-3% was shown. In order to remove some systematical uncertainties and to reach such a good accuracy the execution of comparative diffraction measurements is proposed with a pair of gases having close atomic properties and different n,e-scattering contributions, such as Ar- 36Ar or Xe-Kr.

Mitsyna, L. V.; Nikolenko, V. G.; Parzhitski, S. S.; Popov, A. B.; Samosvat, G. S.

2009-03-01

110

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

111

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

112

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

SciTech Connect

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

John D. Valentine

2005-07-28

113

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

114

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

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

115

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

Microsoft Academic Search

Abstract 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 ,Xe. 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 (B0),

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

116

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

Microsoft Academic Search

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

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

2003-01-01

117

A method for the measurement of the absolute value of the average energy to produce an ion pair in noble gases with X-rays  

Microsoft Academic Search

A method is described that allows the measurement of the absolute value of the average energy to produce an ion pair in noble gases for soft X-rays and its energy dependence. It uses a specially designed gas proportional scintillation counter working under electric fields below the ionization threshold. The spectrum of the radiation absorbed, and thus the number of photons

Filipa I. G. M. Borges; C. A. N. Conde

1992-01-01

118

Noble Gas Analysis of the Julesburg L3.6, Tulia H4, Y-86789 Thermally Metamorphosed CM, and Allende CV3 Chondrites by Crushing Method  

NASA Astrophysics Data System (ADS)

We analyzed noble gases of the Julesburg L3.6, Tulia H4, Y-86789 thermally metamorphosed CM, and Allende CV3 chondrites by the stepped crushing method. All samples have released light noble gases with meteoritic isotopic compositions and heavy noble gases which are contaminated with air to various extents. Total amounts of crash-released noble gases of the four meteorites are estimated to be less than 1% of bulk. Comparing with the results of crushing experiments on the Happy Canyon E6/7 chondrite, the above four meteorites released much smaller fractions of noble gases, suggesting that the four meteorites contain minor amounts of noble gases in places such as microbubbles.

Fukuda, D.; Nakamura, T.; Takaoka, N.; Nagao, K.

1996-03-01

119

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

120

Role of Vacancies in the Adsorption of Quantum Noble Gases inside a Bundle of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Diffusion Monte Carlo calculations on the He4 and Ne20 adsorption in the interstices of a bundle of (10,10) carbon nanotubes are reported. The results indicate that the presence of a carbon vacancy is enough, at least in some cases, to impede the adsorption of quantum gases in those systems. This could explain some discrepancies between the experimental data and the theoretical calculations about the possibility of adsorption of gases inside a bundle of carbon nanotubes.

Gordillo, M. C.

2006-06-01

121

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

NASA Technical Reports Server (NTRS)

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).

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

122

Noble gases and coupled heat/fluid flow modeling for evaluating hydrogeologic conditions of volcanic island aquifers  

NASA Astrophysics Data System (ADS)

SummaryUnderstanding groundwater conditions in the upland parts of volcanic island aquifers is critical for sustainable groundwater development in these resource-limited environments. Yet groundwater conditions in such settings are generally difficult to characterize because of sparse well drilling (high cost and/or limited access). Information needed for resource evaluation includes upland depth to water, recharge rate, and aquifer permeability. In this study, noble-gas recharge temperatures and coupled heat/fluid flow modeling are used to indirectly infer these groundwater conditions. Mosteiros Basin on Fogo Island of the Cape Verde archipelago was selected as a representative volcanic island aquifer. Simulation results are calibrated to water-table altitude and temperature data, along with indirect information provided by noble and dissolved gases. Results of numerical modeling are most sensitive to recharge rates and hydraulic conductivity, less sensitive to basal heat flux, and not sensitive to porosity and thermal conductivity. Simulation results show that only a relatively narrow range of combined recharge values (12-25% of precipitation) and hydraulic conductivity (10-8-10-7 m s-1) is consistent with observed data. The simulated recharge of 3-6 million cubic meters per year (Mm3 yr-1) is much higher than measured discharge from the basin (0.25 Mm3 yr-1), indicating the occurrence of significant amounts of submarine groundwater discharge. The modeling results suggest a very deep upland water table located 600-1000 m beneath the floor of the central caldera, although the water table becomes more shallow and accessible towards the coast. Perhaps most significant is the dominant role that modest amounts of recharge (mean rates of 70-140 mm yr-1) plays in decreasing the geothermal gradient, resulting in relatively cool temperatures in the deep vadose and at the water table. Noble-gas recharge temperatures, constrained by numerical simulation results, range from about 15 to 22 °C and indicate a large water-table temperature lapse of about -15 °C/km, much steeper than typical adiabatic lapse rates.

Heilweil, Victor M.; Healy, Richard W.; Harris, Robert N.

2012-09-01

123

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

PubMed Central

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

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

2010-01-01

124

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

SciTech Connect

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

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

2013-03-15

125

Concerning the width of spark channels with different polarities in submicrosecond sliding discharges in noble gases  

NASA Astrophysics Data System (ADS)

Previously, the parameters of submicrosecond (with a duration of <200 ns) multichannel high-current discharges sliding along a ceramic surface in Ne, Ar, and Xe were studied only for the negative polarity of the applied voltage. The experimental data indicate that the channels expand in the transverse direction mainly due to electron drift from the channel surface layer under the action of the electric field perpendicular to the channel axis and subsequent gas ionization by these electrons. To investigate mechanisms for the channel development in a sliding discharge—in particular, to determine the contribution of electron drift—it is necessary to carry out experiments similar to those performed earlier for the opposite polarity of the applied voltage. Here, the results of measurements of the widths of the spark channels of negativeand positive-polarity sliding discharges excited in Ne, Ar, and Xe at pressures of 30 and 100 kPa are presented and discussed. It is shown that, depending on the pressure and sort of gas, the averaged optical width of positive-polarity channels is smaller by a factor of 1.27-1.60 than that of negative-polarity channels. The experimental data are analyzed using the theory of propagation of ionization waves with different polarities in gases. Analysis has shown that electron diffusion contributes insignificantly to channel expansion and that, for both polarities, the channel expansion rate exceeds the electron drift velocity in the transverse electric field near the channel. In the framework of the so-called approximation of nonlocalized initial conditions, the measured ratio between of the widths of negativeand positive-polarity channels and their relation to the electron mobility are explained by the channel expansion governed by both electron drift and primary free electrons produced by a short-term source in a narrow region ahead of the front of the expansion wave. Numerical simulations show that the width of this region is comparable with that of the wave front and is more than one order of magnitude smaller than the observed channel radius. Gas photoionization by the channel radiation can serve as a source of primary electrons.

Trusov, K. K.

2010-02-01

126

Concerning the width of spark channels with different polarities in submicrosecond sliding discharges in noble gases  

SciTech Connect

Previously, the parameters of submicrosecond (with a duration of <200 ns) multichannel high-current discharges sliding along a ceramic surface in Ne, Ar, and Xe were studied only for the negative polarity of the applied voltage. The experimental data indicate that the channels expand in the transverse direction mainly due to electron drift from the channel surface layer under the action of the electric field perpendicular to the channel axis and subsequent gas ionization by these electrons. To investigate mechanisms for the channel development in a sliding discharge-in particular, to determine the contribution of electron drift-it is necessary to carry out experiments similar to those performed earlier for the opposite polarity of the applied voltage. Here, the results of measurements of the widths of the spark channels of negativeand positive-polarity sliding discharges excited in Ne, Ar, and Xe at pressures of 30 and 100 kPa are presented and discussed. It is shown that, depending on the pressure and sort of gas, the averaged optical width of positive-polarity channels is smaller by a factor of 1.27-1.60 than that of negative-polarity channels. The experimental data are analyzed using the theory of propagation of ionization waves with different polarities in gases. Analysis has shown that electron diffusion contributes insignificantly to channel expansion and that, for both polarities, the channel expansion rate exceeds the electron drift velocity in the transverse electric field near the channel. In the framework of the so-called approximation of nonlocalized initial conditions, the measured ratio between of the widths of negativeand positive-polarity channels and their relation to the electron mobility are explained by the channel expansion governed by both electron drift and primary free electrons produced by a short-term source in a narrow region ahead of the front of the expansion wave. Numerical simulations show that the width of this region is comparable with that of the wave front and is more than one order of magnitude smaller than the observed channel radius. Gas photoionization by the channel radiation can serve as a source of primary electrons.

Trusov, K. K. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

2010-02-15

127

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

SciTech Connect

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

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

2014-01-28

128

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

129

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

Microsoft Academic Search

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

S. Niedermann; O. Eugster

1992-01-01

130

Noble gases as proxies of mean ocean temperature: sensitivity studies using a climate model of reduced complexity  

E-print Network

ocean temperature may be reconstructed from measurements of atmospheric noble gas concentrations in ice temperature is investigated and their sensitivities to changes in ocean volume, ocean salinity, sea are suitable proxies of global mean ocean temperature. Changes in ocean volume need to be considered when

Stocker, Thomas

131

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

E-print Network

. These efforts are continuing and the accuracy of so- lar wind isotopic analyses is increasing. The low concentra in the SW, so little modification to current mass spectrometry was needed to perform these isotopic analyses, with the exception of changes needed to handle the large concentrations of solar wind hydrogen. He and Ne isotopes

132

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

Microsoft Academic Search

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

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

1993-01-01

133

Solubility investigations in support of ultrasensitive noble gas detector development.  

SciTech Connect

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.

Gross, K. C.

1998-08-05

134

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

PubMed Central

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

2013-01-01

135

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

PubMed

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

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

2014-09-18

136

Fullerenes and the Nature of Planetary Gases  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

137

Multiple Ion Counting in Noble Gas Mass Spectrometry  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

138

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

USGS Publications Warehouse

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

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

2010-01-01

139

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

NASA Astrophysics Data System (ADS)

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

Baldwin, S.; Das, J. P.

2013-12-01

140

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

141

Cosmogenic noble gas paleothermometry  

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

142

Noble gas emplacement in shock-produced diamonds  

NASA Astrophysics Data System (ADS)

Amounts of noble gases in shock-produced diamonds were considerably higher than those in the raw material graphite, and their elemental ratios were similar to those of air. It is evident that the shock-produced diamonds trapped the noble gases, without significant mass fractionation, from the atmosphere during the phase transition. These noble gases were mainly released at temperatures within the range of 1700 to 2000 C, suggesting that noble gases were tightly incorporated within the diamonds and were being released during graphitization. A diamond synthesized under hydrostatic pressure was found to have noble gas abundances much lower than those the shock-produced diamonds. The elemental abundances ofnoble gases in shock-produced diamonds are discussed in relation to those in ureilite diamonds.

Matsuda, Jun-Ichi; Nagao, Keisuke

1989-05-01

143

Polarized noble gas MRI  

SciTech Connect

The development of convenient methods to polarize liter quantities of the noble gases helium-3 and xenon-129 has provided the opportunity for a new MRI method to visualize the internal air spaces of the human lung. These spaces are usually poorly seen with hydrogen-based MRI, because of the limited water content of the lung and the low thermal polarization of the water protons achieved in conventional magnets. In addition, xenon, which has a relatively high solubility and a sufficiently persistent polarization level in blood and biological tissue, offers the prospect of providing perfusion images of the lung, brain and other organs.

Brookeman, James R.; Mugler, John P. III; Lange, Eduard E. de; Knight-Scott, Jack; Maier, Therese [Department of Radiology, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908 (United States); Bogorad, Paul; Driehuys, Bastiaan; Cates, Gordon; Happer, William [Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States); Daniel, Thomas M. [Department of Surgery, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908 (United States); Truwit, Jonathon D. [Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908 (United States)

1998-01-20

144

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

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

145

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

NASA Astrophysics Data System (ADS)

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

Kendrick, M. A.; Phillips, D.

2009-10-01

146

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

E-print Network

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

Stanley, Rachel H. R

2007-01-01

147

Except for the noble gases, all the elements in the Periodic Table form chlorides, often in several oxidation states, and chlorides generally are among the  

E-print Network

, e.g. SiCl4, CCl4, but also gases, e.g. HCl, or solids, e.g. PCl5. They form molecular lattices, e.g. NaCl. On the basis of constitution: 1. Simple chlorides: binary compounds, e.g. CCl4, or mixed. The reaction involve treatment of anhydrous compounds, often oxides, with halogen compounds such as CCl4

Csonka, Gábor István

148

The Thermochemical Stability of Ionic Noble Gas Compounds.  

ERIC Educational Resources Information Center

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,…

Purser, Gordon H.

1988-01-01

149

A small 1 MeV electron accelerator for measuring heavy metal concentrations in smokestack gases  

Microsoft Academic Search

A low-current electron beam may be used as a diagnostic tool to measure the concentrations of heavy metals (Pb, Hg, Sb, etc.) present in the flue gas particulates produced by smelters or cement kilns. A small electron accelerator is being constructed as part of a prototype emissions monitoring system. The electron beam energy has a design energy of 1 MeV,

A. Reppond; M. Ambrosia; B. C. Hansen; C. R. Meitzlerf; D. P. Redden; D. A. Swenson

1997-01-01

150

A small 1 MeV electron accelerator for measuring heavy metal concentrations in smokestack gases  

Microsoft Academic Search

A low-current electron beam may be used as a diagnostic tool to measure the concentrations of heavy metals (Cd, Pb, Hg) present in the flue gas particulates produced by smelters or cement kilns. A small electron accelerator is being constructed as part of a prototype emissions monitoring system. The electron beam energy has a design energy of 1 MeV, a

A. Reppond; D. P. Redden; C. R. Meitzler; D. A. Swenson

1997-01-01

151

Advances in noble gas paleothermometry on speleothems  

NASA Astrophysics Data System (ADS)

The application of the noble gas paleothermometer on speleothem fluid inclusions promises to provide absolute paleotemperatures from stalagmites. These noble gas temperatures (NGTs) are based on the temperature dependent solubility of gases in water and could help to interpret other speleothem proxies. In particular NGTs may help to better understand oxygen isotope records. In summer and autumn 2009 a measurement run with 26 (sub-)samples from 9 different caves was performed. The water and the noble gases were released using a stepwise extraction technique by online in vacuo crushing and thermal heating. Depending on the sample water amount about three extraction steps were performed for each sample, so that the total number of speleothem measurements exceeded 80 in this run. NGTs were determined from noble gas concentrations by inverse modeling. Only the equilibrium solubility component, which contains the temperature information, and an atmospheric air component from air-filled inclusions are included in the calculations. Plots of two noble gas concentrations against each other (Xe-Ne, Kr-Ar) show that the measured concentrations are in general agreement with this simple model. Unfortunately the combined mass spectrometric measurement of Ar, Kr and Xe turned out to be slightly problematic. A separated measurement should solve the corresponding problems. Furthermore, a lab water standard for noble gases will be prepared to further examine the measurements in the future. In this measurement run samples from not only Bunker Cave (Germany) showed suitable properties for NGT determination but also samples from Katerloch Cave (Austria) where the water concentration varies between 0.4 to 4 ?l per g calcite which is comparable to the Bunker Cave stalagmites. The air to water volume ratio is below 0.1 which in principle allows the determination of NGTs with errors in the range of 1 °C. The calculated NGTs are in the range of the modern cave air temperature.

Marx, Thomas; Kluge, Tobias; Mangini, Augusto; Aeschbach-Hertig, Werner

2010-05-01

152

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

SciTech Connect

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

Chan, S.T.

1997-09-01

153

LaRC results on nuclear pumped noble gas lasers  

NASA Technical Reports Server (NTRS)

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.

Deyoung, R. J.

1979-01-01

154

A proper mobility formula for large, heavy particles in gases in any regime  

NASA Astrophysics Data System (ADS)

The age-old problem of the derivation of a proper formula for the mechanical (or electrical) mobility of large, heavy (l.h.) particles in a simple neutral gas in any regime is carefully examined and solved under the usual hypotheses that the l.h. particles are subject to the action of a constant external force and undergo only elastic collisions with the gas particles. By a convenient procedure, a general mobility formula is obtained which not only properly corrects the well-known result derived by Cunningham for an l.h. hard sphere in a hard-sphere gas, but also applies to the general case in which both the l.h.-particle-gas-particle and gas-particle-gas-particle interactions are arbitrary. In addition, on the basis of the new formula, the fair success of the Cunningham formula (regarded as a semiempirical formula) in fitting the experimental results is explained. Other interesting aspects of the new formula are also examined, and its limits of validity are briefly discussed.

Ferrari, Leonardo

2000-07-01

155

Noble gas magnetic resonator  

DOEpatents

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.

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

2014-04-15

156

Computational investigation of noble gas adsorption and separation by nanoporous materials  

Microsoft Academic Search

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

Mark D. Allendorf; Joseph C. Sanders; Jeffery A. Greathouse

2008-01-01

157

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...

158

Noble gas excimer scintillation following neutron capture in boron thin films  

SciTech Connect

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

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

2014-04-14

159

Biomedical Investigations with Laser-Polarized Noble Gas Magnetic Resonance  

NASA Technical Reports Server (NTRS)

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.

Walsworth, Ronald L.

2003-01-01

160

Air-Xe enrichments in Elk Hills oil field gases: role of water in migration and storage  

NASA Astrophysics Data System (ADS)

Hydrocarbons from the Elk Hills Naval Petroleum Reserve (NPR#1), Bakersfield, CA, are enriched in heavy noble gases. The 132Xe/ 36Ar ratios are as high as ˜576 times the ratio in air and represent the largest relative Xe-enrichments ever observed in terrestrial fluids. The Xe isotopic composition is indistinguishable from air. We show that these samples cannot be explained by equilibration of oil with air saturated water and secondary enrichment via a Rayleigh distillation gas stripping process. Based on laboratory studies of others with potential petroleum source rocks, we believe the source of this enriched heavy noble gas component was adsorbed air initially trapped in/on the source rocks that was expelled and mixed with the hydrocarbons during expulsion and primary migration. Kr and Xe enrichments decrease with increasing 36Ar concentration. We propose a model in which an initial Kr-Xe-enriched hydrocarbon becomes diluted with noble gases extracted from air saturated groundwater during expulsion, migration, and storage. The model generates an integrated water/hydrocarbon ratio for the production fluid which indicates a minimal role for water in hydrocarbon expulsion and migration. The results are interpreted to provide time/geometrical constraints on the mechanisms by which hydrocarbons can migrate as a separate phase.

Torgersen, T.; Kennedy, B. M.

1999-04-01

161

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

162

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

NASA Astrophysics Data System (ADS)

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

Ozima, M.

2010-12-01

163

History of trace gases in presolar diamonds inferred from ion-implantation experiments.  

PubMed

Diamond grains are the most abundant presolar grains found in primitive meteorites. They formed before the Solar System, and therefore provide a record of nuclear and chemical processes in stars and in the interstellar medium. Their origins are inferred from the unusual isotopic compositions of trace elements-mainly xenon-which suggest that they came from supernovae. But the exact nature of the sources has been enigmatic, as has the method by which noble gases were incorporated into the grains. One observation is that different isotopic components are released at different temperatures when the grains are heated, and it has been suggested that these components have different origins. Here we report results of a laboratory study that shows that ion implantation (previously suggested on other grounds) is a viable mechanism for trapping noble gases. Moreover, we find that ion implantation of a single isotopic composition can produce both low- and high-temperature release peaks from the same grains. We conclude that both isotopically normal and anomalous gases may have been implanted by multiple events separated in space and/or time, with thermal processing producing an apparent enrichment of the anomalous component in the high-temperature release peak. The previous assumption that the low- and high-temperature components were not correlated may therefore have led to an overestimate of the abundance of anomalous argon and krypton, while obscuring an enhancement of the light-in addition to the heavy-krypton isotopes. PMID:11493913

Koscheev, A P; Gromov, M D; Mohapatra, R K; Ott, U

2001-08-01

164

Viscosity and pVT-Second Virial Coefficient of Binary Noble-Globular Gas and Globular-Globular Gas Mixtures Calculated by Means of an Isotropic Temperature-Dependent Potential  

NASA Astrophysics Data System (ADS)

This work presents results of an extension of our earlier studies of the transport and equilibrium properties of pure heavy globular gases. It demonstrates a simple and reliable procedure for estimating the equilibrium and transport properties of their mixtures using the pure gas potentials of interaction when there are no available experimental data. Here we consider binary gas mixtures of globular gases between themselves and with the noble gases as well. The gases involved are: BF3, CH4, CF4, SiF4, SiCl4, CCl4, SF6, MoF6, WF6, UF6, C(CH3)4, Si(CH3)4, Ar, Kr, and Xe. The calculations were performed by means of the so called isotropic temperature-dependent potential (ITDP) introduced by us earlier and applied to some binary mixtures (CH4-CF4, CH4-SF6, CF4-SF6). The CH4-CH4 and noble gases potentials of interactions have been determined in a (n-6) Lennard-Jones shape in the temperature range 200-1000 K by fitting a large number of viscosity and pVT-second virial coefficient data measured by different authors with different experimental techniques. The ITDP parameters of molecular gases were taken from the tables we have determined and published earlier [L. Zarkova and U. Hohm, J. Phys. Chem. Ref. Data 31, 183 (2002)]. Simple combination rules allow us to take into account the influence of the temperature on the thermophysical properties of the binary gas mixtures containing heavy globular molecules. Tables with potential parameters of equal and unequal particles and properties of the equimolar mixtures are given for all mixtures in the temperature range 200-900 (1000) K. The deviations between experimental and calculated viscosity and second virial coefficient data of some more examined mixtures permit to evaluate the quality of the proposed approach.

Zarkova, L.; Hohm, U.; Damyanova, M.

2003-12-01

165

Biomedical Investigations with Laser-Polarized Noble Gas Magnetic Resonance  

NASA Technical Reports Server (NTRS)

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.

Walsworth, Ronald L.

2001-01-01

166

Greenhouse Gases  

MedlinePLUS

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

167

On the possible noble gas deficiency of Pluto's atmosphere  

E-print Network

We use a statistical-thermodynamic model to investigate the formation and composition of noble-gas-rich clathrates on Pluto's surface. By considering an atmospheric composition close to that of today's Pluto and a broad range of surface pressures, we find that Ar, Kr and Xe can be efficiently trapped in clathrates if they formed at the surface, in a way similar to what has been proposed for Titan. The formation on Pluto of clathrates rich in noble gases could then induce a strong decrease in their atmospheric abundances relative to their initial values. A clathrate thickness of order of a few centimeters globally averaged on the planet is enough to trap all Ar, Kr and Xe if these noble gases were in protosolar proportions in Pluto's early atmosphere. Because atmospheric escape over an extended period of time (millions of years) should lead to a noble gas abundance that either remains constant or increases with time, we find that a potential depletion of Ar, Kr and Xe in the atmosphere would best be explained ...

Mousis, Olivier; Mandt, Kathleen E; Schindhelm, Eric; Weaver, Harold A; Stern, S Alan; Waite, J Hunter; Gladstone, Randy; Moudens, Audrey

2013-01-01

168

Perspectives of hyperpolarized noble gas MRI beyond 3He  

PubMed Central

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

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

2013-01-01

169

A note on the systematics of noble gas abundance ratios in the solar system  

NASA Astrophysics Data System (ADS)

It is demonstrated that there is a general regularity in all noble gas elemental patterns in the atmospheres of the planets. A number of models are proposed to explain this, and these models are examined and judged. In order to explain the observed elemental gas ratios, it is proposed that they may have resulted from selective loss of noble gas from the initial atmospheres of the terrestrial or other planets; that they may be due to solar wind irradiation of the planets and their small precursor bodies; or the noble gases were imported by carrier grains with their peculiar abundance ratio already fixed.

Shukolyukov, Yu. A.

1991-04-01

170

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

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

171

Photoionization of noble-gas atoms by ultrashort electromagnetic pulses  

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

172

High temperature, oxidation resistant noble metal-Al alloy thermocouple  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

173

Global budgets for non-CO 2 greenhouse gases  

Microsoft Academic Search

The most abundant gases in dry air, N 2 (~ 78.1% by volume) and O 2 (~ 20.95% by volume), represent the equilibrium state of global biogeochemical processes that have operated on time scales of many millions of years. Among the remaining gases, the noble gas argon (~- 0.93 % by volume) is by far most abundant. Because of their

Paul J. Crutzen

1994-01-01

174

The trapped noble gas component in achondrites  

NASA Astrophysics Data System (ADS)

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

Busemann, Henner; Eugster, Otto

2002-12-01

175

Chelsea Bonetti Stephanie Noble  

E-print Network

· Disadvantages · Efficiency of single stage · Serpentine flow · BUT!... Multi-Stage · Highest Efficiency/H Ratios) Recovery, Efficiency vs. Applied Voltage Different C/H Ratios #12;Process · Inlet Gases the inlet side · In a Multi-Stage Pump, this goes to the next pump. How a Hydrogen Pump Works A Chemical

Petta, Jason

176

Manure Gases  

MedlinePLUS

... of manure. The gases of most concern are ammonia and hydrogen sulfide. Other gases of concern include ... in low areas of manure storage or accumulation. Ammonia, which is lighter than air, is found above ...

177

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

PubMed

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

Mondal, Sukanta; Chattaraj, Pratim Kumar

2014-09-01

178

Helium Solubility in Cyclosilicates and Implications for Noble Gas Recycling  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

179

Highly sensitive measurements of radioactive noble gas nuclides in the BOREXINO solar neutrino experiment.  

PubMed

Low background miniaturized proportional counters as developed for the GALLEX solar neutrino experiment can be applied to the detection of radioactive noble gas nuclides at very low activities. We have developed an apparatus that allows the activity of trace amounts of isotopes of the four noble gases Ar, Kr, Xe and Rn to be measured. The technique includes contamination-free chromatographic purification of raw gas samples and subsequent low-level counting. Minimum detectable activities of 100 microBq and below have been attained. The developed techniques can be used to determine the 222Rn and 85Kr concentration in nitrogen for the solar neutrino experiment BOREXINO. By applying efficient techniques to concentrate noble gases from nitrogen, minimum detectable activity concentrations below 1 microBq/m3 of nitrogen (STP) have been reached for both nuclides. PMID:15177347

Simgen, H; Heusser, G; Zuzel, G

2004-01-01

180

Dating native gold by noble gas analyses  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

181

Thermometry in noble gas dielectric barrier discharges at atmospheric pressure using optical emission spectroscopy  

Microsoft Academic Search

We measure the temperature, T, of dielectric barrier discharges (DBD), in noble gases using optical emission spectroscopy (OES), by analysing rotational bands in the emission spectra of the first negative system (FNS) of N2 + . This has the advantage that rotational structure can be fully resolved even with a spectrograph of average performance, and that the rotational temperature, Trot

Aziz Berchtikou; Joel Lavoie; Viorel Poenariu; Bachir Saoudi; Raman Kashyap; Michael R. Wertheimer

2011-01-01

182

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

NASA Astrophysics Data System (ADS)

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 reliable palaeotemperature information on the time range from present back to hundred thousand years. [1] Kluge T., Marx T., Scholz D., Niggermann S., Mangini A., Aeschbach-Hertig W., 2008. A new tool for palaeoclimate reconstruction: Noble gas temperatures from fluid inclusions in speleothems. Earth and Planetary Science Letters 269, 408-415. [2] Brennwald M.S., Scheidegger Y., Tomonaga Y., Holzner C.P., Wieler R., Kipfer R., 2006. New applications of noble gases as environmental proxies in unusual aquatic environments. Geochimica et Csomochimica Acta 70, Supplement, A66.

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

2010-05-01

183

NOBLE GAS PRODUCTION FROM MERCURY SPALLATION AT SNS  

SciTech Connect

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.

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

2013-01-01

184

Noble gases and radiocarbon in natural gas hydrates Gisela Winckler  

E-print Network

]). The analysis of stable carbon and hydrogen isotopes of the dominant guest molecule methane allows to establish Kipfer Institute of Isotope Geology and Mineral Resources, ETH, Zurich, Switzerland Department of Water are not incorporated into the structure of natural methane hydrates. In contrast, the hydrates contain significant

Aeschbach-Hertig, Werner

185

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

NASA Technical Reports Server (NTRS)

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

Cess, R.; Owen, T.

1973-01-01

186

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

ERIC Educational Resources Information Center

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

Chernick, Cedric L.

187

Noble Gas Partitioning Between Olivine and Melt to 2 GPa  

NASA Astrophysics Data System (ADS)

We have extended our experimental measurements of noble gas partition coefficients to 2 GPa in the piston-cylinder device. The experimental set-up involves surrounding wafers of gem quality San Carlos olivine (250-1000 microns thick, 3-4 mm diameter) with diamond powder or vitreous carbon spheres. A layer of melt is placed at the bottom of the capsule which infiltrates the porous media and touches the olivine. This allows the original surface of the crystal to be identified and large coherent pieces of olivine to be recovered intact. The inner capsule is graphite and the outer capsule is Pt. Up to 60 bars of HeNeAr were preloaded into the Pt capsule before it was welded shut. This method combines a number of desireable qualities: 1) it avoids producing melt inclusions in the olivine, 2) it yields large areas of olivine to analyze by laser-ablation and 3) it has both melt and crystals present and in contact. The experimental glasses and olivine wafers were analyzed by laser-ablation noble gas mass spectrometry at the Open University, UK. Both depth profiles and cross-sections were analyzed on the olivine wafers. Equilibrium (flat) concentration profiles were only obtained for He in our experiments (up to 20 hr run durations). These yield olivine-melt partition coefficients (D) between 0.0007 and 0.002 at 1-2 GPa and at 1450. These values are within the range of measurements at low pressures (100 MPa or less), suggesting a minimal pressure effect on noble gas partitioning in the upper mantle. Henry’s Law behavior is maintained over 4 orders of magnitude variation in He concentration in the olivine (0.0001 to 1 ppm He). High near-surface concentrations of He (21ppm), Ne (36ppm) and Ar (4,360ppm) were observed in the olivine. The thickness of the enriched layer (5 microns) was the same for all three noble gases. We do not know the origin of the high near-surface concentrations, but if they were due to lattice diffusion of the noble gases, the thickness of the high concentration layer should decrease with the diffusivity of the noble gas from He to Ne to Ar. Thus we speculate that the high near-surface concentrations are due to a change in the material properties of the olivine.

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

2009-12-01

188

Greenhouse Gases  

MedlinePLUS

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

189

Deep plume origin of the Louisville hotspot: Noble gas evidence  

NASA Astrophysics Data System (ADS)

gas compositions have been reported for basaltic core samples from Louisville seamounts recovered during IODP Expedition 330. The in-vacuum crushing techniques were employed to extract noble gases from fresh olivine phenocrysts and submarine glasses with ages between 50 and 74 Ma. Stepwise crushing tests confirmed the extraction of magmatic noble gases from the olivine samples with minimal release of posteruption radiogenic nuclides; however, this was not always the case for the glass samples. The 3He/4He ratios of the studied samples range from a value similar to those of mid-ocean ridge basalts (MORB) to slightly elevated ratios up to 10.6 Ra. These ratios are not as high as those observed in other ocean island basalts, suggesting that the Louisville mantle plume was weak or the samples represent late-stage magmatic activity of the seamounts. However, two Louisville seamount basalts exhibit a primordial Ne isotopic signature that can be clearly discriminated from MORB Ne ratios. The He and Ne isotopic compositions of the Louisville seamount basalts can be explained by the mixing of less degassed mantle and depleted upper mantle with different He/Ne ratios. The presence of the less degassed mantle component in the source of the Louisville seamounts documents a deep origin of their mantle plume.

Hanyu, Takeshi

2014-03-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

191

Atmospheric gases  

NSDL National Science Digital Library

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

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

2003-01-01

192

MR-compatible ventilator for small animals: computer-controlled ventilation for proton and noble gas imaging  

E-print Network

MR-compatible ventilator for small animals: computer-controlled ventilation for proton and noble; accepted 28 April 2000 Abstract We describe an MR-compatible ventilator that is computer controlled, and to support delivery of gas anesthesia and experimental inhalational gases. A key feature of this ventilator

193

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

SciTech Connect

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.

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

2008-10-01

194

Cryogenic method for measuring nuclides and fission gases  

DOEpatents

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

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

1980-05-02

195

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

196

Greenhouse Gases  

NSDL National Science Digital Library

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

2012-08-03

197

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

E-print Network

We present a model explaining 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 ($\\sim$3 times solar, relative to H). Being volatile, Ar is difficult to fractionate from ${\\rm H}_{2}$. We argue that external photoevaporation by far ultraviolet (FUV) radiation from nearby massive stars removed ${\\rm H}_{2}$, 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 ($\\lt 30$ K) to trap them in amorphous water ice. As the solar nebula lost H it became relatively and uniformly enriched in other species. Our model improves on the similar model of Guillot \\& Hueso (2006). We recognize that cold temperatures alone do not trap volatiles; continuous water vapor production also is necessary. We demonstrate that FUV fluxes that photoevaporated the disk generated sufficient water va...

Monga, Nikhil

2014-01-01

198

Recovery and use of fission product noble metals  

SciTech Connect

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

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

1980-06-01

199

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

SciTech Connect

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.

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

2011-10-01

200

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

NASA Technical Reports Server (NTRS)

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.

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

201

Noble Foundation Plant Image Gallery  

NSDL National Science Digital Library

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

202

Incorporation of noble metals into aerogels  

DOEpatents

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

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

1998-12-22

203

Incorporation of noble metals into aerogels  

DOEpatents

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

Hair, Lucy M. (Livermore, CA); Sanner, Robert D. (Livermore, CA); Coronado, Paul R. (Livermore, CA)

1998-01-01

204

Separation of polar gases from nonpolar gases  

Microsoft Academic Search

Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol

S. Kulprathipanja; S. S. Kulkarni

1986-01-01

205

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

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

206

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

NASA Astrophysics Data System (ADS)

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

Papp, Laszlo; Palcsu, Laszlo; Major, Zoltan

2010-05-01

207

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

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

208

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

SciTech Connect

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.

Carrigan, C R; Sun, Y

2011-01-21

209

Effects of atmospheric entry heating on the noble gas and nitrogen content of micrometeorites  

NASA Astrophysics Data System (ADS)

Fragments of the carbonaceous chondrite Orgueil were subjected to pulse-heating sequences in order to simulate the heating conditions experienced by micrometeorites (MMs) upon entry into Earth's atmosphere. By increasing the experimental run times from 2 to 120 s at a fixed temperature of 1350?°C, the different textures of natural MMs (from non-vesicular fine-grained particles to melted cosmic spherules) were reproduced, and the noble gas (He, Ne, Ar) and nitrogen abundances and isotope ratios of the MM analogues were subsequently determined by CO2 laser extraction-static mass spectrometry analysis. The starting material shows a heterogeneous He-Ne-Ar-N signature, consistent with the mineralogical heterogeneity of CI chondrites and the inhomogeneous distribution of various noble gas and nitrogen components among meteoritic minerals. Nonetheless, our experiments demonstrate that moderately to strongly heated Orgueil fragments retain only a few percent of their initial noble gas and nitrogen inventories, indicating that atmospheric entry heating results in extensive degassing of meteoritic dust particles. The evolution of the noble gas and nitrogen isotope ratios may, in part, be explained by equilibration with the atmosphere; however, the decreasing ?15N values may also indicate preferential degradation of a 15N-rich component by thermal processing of chondritic matter. Furthermore, the efficient loss of helium and cosmogenic neon during heating will lead to an underestimate of the 3He and 21Ne exposure ages of MMs, as well as to large uncertainties for cosmic dust accretion rates derived from extraterrestrial 3He abundances in deep-sea sediments or polar ice cores. While the relative proportions of infalling cometary and asteroidal dust on Earth are unknown, the contribution of noble gases, nitrogen, and water from cosmic dust to the terrestrial volatile inventory appears negligible.

Füri, Evelyn; Aléon-Toppani, Alice; Marty, Bernard; Libourel, Guy; Zimmermann, Laurent

2013-09-01

210

Noble Metal Nanoparticles for Biosensing Applications  

PubMed Central

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

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

2012-01-01

211

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

SciTech Connect

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

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

2007-06-13

212

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

DOEpatents

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.

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

2008-06-10

213

Rare gases systematics and mantle structure  

NASA Technical Reports Server (NTRS)

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

Allegre, C. J.; Staudacher, T.

1994-01-01

214

Barnes and Noble @ e University of Houston  

E-print Network

Games Room Starbucks B30 Creation Station B17 B12 Barnes and Noble @ e University of Houston Coog Radio Daily Cougar Student Video Network N221 Student Government Association N220 N212 Synergy Women's Resource Center LGBT Resource Center N201 Veterans' Services O ce N202 Elevator Elevator UC

Azevedo, Ricardo

215

Noble liquid detectors for dark matter.  

NASA Astrophysics Data System (ADS)

Experiments based on noble liquid targets are now providing competitive sensitivities in the race for the direct detection of particle dark matter. Theoretical estimates, based on supersymmetric models predict dark matter interaction rates from the best sensitivity of existing direct detection experiments of ˜1 evts/kg/month, down to rates of ˜1 evts/100 kg/yr, and below this. Current noble liquid experiments for dark matter searches, range in scale from 10 to 1000 kg, and are designed to rise to this challenge. Ar, Ne and Xe targets permit the discrimination of electron recoils, coming from gamma ray and beta backgrounds, versus nuclear recoils, characteristic of WIMP events. This is done using scintillation light pulse shapes, and/or the ratio of ionization to scintillation generated in the target by the interaction. The detectors are also able to significantly reduce backgrounds through the use of position resolution in large volumes, combined with active self-shielding, to reach very low levels in inner fiducial volumes. A growing understanding of how to exploit these characteristics, and construct larger detectors, will allow further significant improvements in the sensitivity of noble liquid experiments. Current and future noble liquid detector experiments include: ArDM, LUX, (mini)CLEAN/DEAP, WARP, XENON, XMASS, XMASS-DM, ZEPLIN

Gaitskell, Richard

2007-04-01

216

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

NASA Astrophysics Data System (ADS)

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 and St. John's Dome fields. Stage 2: The noble gases re-dissolve into any available gas stripped groundwater. This is modeled as a Rayleigh distillation process and enables us to quantify for each sample: (1) the volume of groundwater originally 'stripped' on reservoir filling; and (2) the volume of groundwater involved in subsequent interaction. The original water volume that is gas stripped varies from as low as 0.0005 cm 3 groundwater/cm 3 gas (STP) in one Bravo Dome sample, to 2.56 cm 3 groundwater/cm 3 gas (STP) in a St. John's Dome sample. Subsequent gas/groundwater equilibration varies within all fields, each showing a similar range, from zero to ˜100 cm 3 water/cm 3 gas (at reservoir pressure and temperature).

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

2008-02-01

217

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

E-print Network

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

Capolupo, Antonio; Illuminati, Fabrizio

2013-01-01

218

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

PubMed

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

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

2013-10-01

219

Catalytic combustion of actual low and medium heating value gases  

NASA Technical Reports Server (NTRS)

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

Bulzan, D. L.

1982-01-01

220

Dipolar Gases -- Theory  

NASA Astrophysics Data System (ADS)

In this chapter, we briefly review some important aspects of the theory of dipolar gases, focusing on those aspects in which the physics of dipolar gases differs qualitatively from that of non-dipolar ones.

Santos, Luis

2015-09-01

221

Electrical breakdown of gases  

Microsoft Academic Search

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

J. M. Meek; J. D. Craggs

1978-01-01

222

Applications of Noble Gas Radiation Detectors to Counter-terrorism  

NASA Astrophysics Data System (ADS)

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).

Vanier, Peter E.; Forman, Leon

2002-10-01

223

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

NASA Astrophysics Data System (ADS)

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

Monga, Nikhil; Desch, Steven

2015-01-01

224

Separation of polar gases from nonpolar gases  

DOEpatents

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

Kulprathipanja, Santi (Hoffman Estates, IL)

1986-01-01

225

Separation of polar gases from nonpolar gases  

DOEpatents

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

Kulprathipanja, S.

1986-08-19

226

Separation of polar gases from nonpolar gases  

DOEpatents

Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

Kulprathipanja, S.; Kulkarni, S.S.

1986-08-26

227

Separation of polar gases from nonpolar gases  

DOEpatents

Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

Kulprathipanja, Santi (Hoffman Estates, IL); Kulkarni, Sudhir S. (Hoffman Estates, IL)

1986-01-01

228

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

NASA Technical Reports Server (NTRS)

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.

Burgess, Raymond; Turner, Grenville

1994-01-01

229

Highly Fluorescent Noble Metal Quantum Dots  

PubMed Central

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

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

2009-01-01

230

Alloys cathodically modified with noble metals  

Microsoft Academic Search

The truly remarkable corrosion resistance of alloys containing small amounts of noble metals relies on the principle that the high exchange-current density for the reduction of hydrogen can shift the corrosion potential of the alloy to a value in the passive region, causing it to passivate spontaneously. Research indicates that additions of 0.1 to 0.4% PGMs to chromium in sulphuric

J. H. Potgieter

1991-01-01

231

Statistical properties of groundwater noble gas paleoclimate models: Are they robust and unbiased estimators?  

Microsoft Academic Search

Noble gas paleoclimate reconstructions from noble gas concentrations in groundwater have the promise of providing absolute paleotemperature information, but difficulties in modeling measured noble gas concentrations with simple models have led to a number of competing noble gas temperature (NGT) schemes being developed. These different models make different assumptions about the size and nature of the noble gas air-saturated water

Tie Sun; Chris M. Hall; Maria Clara Castro

2010-01-01

232

Noble metallic nanostructures: preparation, properties, applications  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

233

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

SciTech Connect

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

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

2014-02-28

234

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)

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.

Farley, Kenneth; Mcinnes, Brent; Patterson, Desmond

1994-01-01

235

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

NASA Astrophysics Data System (ADS)

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

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

1994-07-01

236

Spectral reshaping and pulse compression via sequential filamentation in gases.  

PubMed

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

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

2008-01-01

237

Noble gas constraints on air-sea gas exchange and bubble fluxes  

NASA Astrophysics Data System (ADS)

Air-sea gas exchange is an important part of the biogeochemical cycles of many climatically and biologically relevant gases including CO2, O2, dimethyl sulfide and CH4. Here we use a three year observational time series of five noble gases (He, Ne, Ar, Kr, and Xe) at the Bermuda Atlantic Time series Study (BATS) site in tandem with a one-dimensional upper ocean model to develop an improved parameterization for air-sea gas exchange that explicitly includes separate components for diffusive gas exchange and bubble processes. Based on seasonal timescale noble gas data, this parameterization, which has a 1? uncertainty of ±14% for diffusive gas exchange and ±29% for bubble fluxes, is more tightly constrained than previous parameterizations. Although the magnitude of diffusive gas exchange is within errors of that of Wanninkhof (1992), a commonly used parameterization, we find that bubble-mediated exchange, which is not explicitly included by Wanninkhof (1992) or many other formulations, is significant even for soluble gases. If one uses observed saturation anomalies of Ar (a gas with similar characteristics to O2) and a parameterization of gas exchange to calculate gas exchange fluxes, then the calculated fluxes differ by ˜240% if the parameterization presented here is used compared to using the Wanninkhof (1992) parameterization. If instead one includes the gas exchange parameterization in a model, then the calculated fluxes differ by ˜35% between using this parameterization and that of Wanninkhof (1992). These differences suggest that the bubble component should be explicitly included in a range of marine biogeochemical calculations that incorporate air-sea gas fluxes.

Stanley, Rachel H. R.; Jenkins, William J.; Lott, Dempsey E.; Doney, Scott C.

2009-11-01

238

Trends in source gases  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

239

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

USGS Publications Warehouse

Here we report anhydrous chemical (CO2, H2S, N2, H2, CH4, O2, Ar, He, Ne) and isotopic (3He/4He, 40Ar/36Ar, ?13C of CO2, ?13C of CH4, ?15N) compositions of virtually airfree gas samples collected between 1994 and 1998 from 12 quiescent but potentially restless volcanoes in the Cascade Range and Aleutian Arc (CRAA). Sample sites include ?173°C fumaroles and springs at Mount Shasta, Mount Hood, Mount St. Helens, Mount Rainier, Mount Baker, Augustine Volcano, Mount Griggs, Trident, Mount Mageik, Aniakchak Crater, Akutan, and Makushin. The chemical and isotopic data generally point to magmatic (CO2, Ar, He), shallow crustal sedimentary (hereafter, SCS) (CO2, N2, CH4), crustal (He), and meteoric (N2, Ar) sources of volatiles. CH4 clearly comes from SCS rocks in the subvolcanic systems because CH4 cannot survive the higher temperatures of deeper potential sources. Further evidence for a SCS source for CH4 as well as for non-mantle CO2 and non-meteoric N2 comes from isotopic data that show wide variations between volcanoes that are spatially very close and similar isotopic signatures from volcanoes from very disparate areas. Our results are in direct opposition to many recent studies on other volcanic arcs (Kita and others, 1993; Sano and Marty, 1995; Fischer and others, 1998), in that they point to a dearth of subducted components of CO2 and N2 in the CRAA discharges. Either the CRAA volcanoes are fundamentally different from volcanoes in other arcs or we need to reevaluate the significance of subducted C and N recycling in convergent-plate volcanoes.

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

2003-01-01

240

Transport of Trace Gases  

NASA Technical Reports Server (NTRS)

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

Schoeberl, Mark R.

2005-01-01

241

ANALYSIS OF PROTOCOL GASES  

EPA Science Inventory

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

242

USE OF SIX SIGMA TOOLS TO REDUCE NOBLE METAL LOSSES  

Microsoft Academic Search

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

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

243

the sam noble oklahoma museum of natural history  

E-print Network

the sam noble oklahoma museum of natural history annual report july 2006­june 2007 #12;board and steve Wright mission statement, adopted december 2003 the sam noble oklahoma museum of natural history at the university of oklahoma inspires minds to understand the natural and cultural world through collection

Oklahoma, University of

244

Noble gas storage and delivery system for ion propulsion  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

245

Noble-metal-free plasmonic photocatalyst: hydrogen doped semiconductors  

PubMed Central

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

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

2014-01-01

246

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

PubMed

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

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

2013-02-28

247

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

248

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

NASA Technical Reports Server (NTRS)

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.

Walsworth, Ronald L.

2004-01-01

249

Polyacrylonitrile/noble metal/SiO2 nanofibers as substrates for the amplified detection of picomolar amounts of metal ions through plasmon-enhanced fluorescence.  

PubMed

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

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

2014-12-10

250

Regulating Greenhouse Gases  

NSDL National Science Digital Library

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

KQED

251

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

USGS Publications Warehouse

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.

Böhlke, J.K.; Irwin, J.J.

1992-01-01

252

Optical response of noble metal alloy nanostructures  

NASA Astrophysics Data System (ADS)

The optical response, stability, and cost-effectiveness of individual noble metals can be improved by combining them to form alloy nanostructures. The present work reveals the influence of shape, size, and metal type on the optical response of alloy nanoparticles using discrete dipole approximation (DDA) simulations. It is found that sharp corner nanostructures show enhanced plasmonic properties in comparison to rounded counterpart. For all the three shapes, viz., nanocubes, rectangular, and nanobar particles, the increase in length resulted in redshifts of the longitudinal plasmon resonance alongwith enhancement in the scattering yield as well as relative efficiency parameters except for nanocubes of edge length 120 nm. The effect of size on full width at half maxima (FWHM) has also been studied and found to be maximal for nanocubes in comparison to other nanostructures.

Bansal, Amit; Verma, S. S.

2015-01-01

253

Total scattering cross sections and interatomic potentials for neutral hydrogen and helium on some noble gases  

SciTech Connect

Measurements of energy-dependent scattering cross sections for 30 to 1800 eV D incident on He, Ne, Ar, and Kr, and for 40 to 850 eV He incident on He, Ar, and Kr are presented. They are determined by using the charge-exchange efflux from the Princeton Large Torus tokamak as a source of D or He. These neutrals are passed through a gas-filled scattering cell and detected by a time-of-flight spectrometer. The cross section for scattering greater than the effective angle of the apparatus (approx. =20 mrad) is found by measuring the energy-dependent attenuation of D or He as a function of pressure in the scattering cell. The interatomic potential is extracted from the data.

Ruzic, D.N.; Cohen, S.A.

1985-04-01

254

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

NASA Astrophysics Data System (ADS)

We demonstrate that the nanoparticle formation during laser ablation of metals by short (of a few tens of ps) laser pulses strongly depends on the concentration of surrounding gas. While, at vacuum conditions, nanoparticle formation shows very “sharp” atomic force microscope images of aggregated clusters, following with clear appearance of plasmon resonance on the absorption spectra of deposited films, an addition of gas particles starts to decrease the probability of cluster formation. This process shows a threshold for both helium (33 torr) and xenon (12 torr) above which no surface plasmon resonance and correspondingly no observable nanoparticles on the deposited surfaces were detected. The destruction of nanoparticle formation was attributed to the negative influence of surrounding gas particles on ablated particles aggregation.

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

2010-07-01

255

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

Microsoft Academic Search

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

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

2001-01-01

256

Noble Gases in the Murchison Meteorite: Possible Relics of s-Process Nucleosynthesis  

Microsoft Academic Search

The Murchison carbonaceous chondrite contains a new type of xenon component, enriched by up to 50 percent in five of the nine stable xenon isotopes, mass numbers 128 to 132. This component is released at 1200 to 1600 C from a severely etched mineral fraction. Krypton shows a similar but smaller enrichment in the isotopes 80 and 82. Neon and

B. Srinivasan; Edward Anders

1978-01-01

257

Mantle, crustal and atmospheric noble gases in ailaoshan gold deposits, Yunnan Province, China  

Microsoft Academic Search

Helium and argon isotopic and elemental compositions of fluids released by crushing pyrite grains are reported from the Ailaoshan Gold Province, China. The province is a series of gold deposits hosted on a 200-km segment of a major normal fault formed during Eocene extension. The deposits have been well characterised using conventional geochemical and microthermometric techniques, the results of which

P. G. Burnard; R. Hu; G. Turner; X. W. Bi

1999-01-01

258

First investigation of noble gases in the Dengli H3,8 chondrite  

NASA Technical Reports Server (NTRS)

The Dengli (H3,8) meteorite, which weighs 243.5 g, is a find from the Karakum desert. It is a complex microbreccia containing unusual clasts which are more typical for regolithic breccias than for H-chondrites. Based on comparisons of Xe and Kr content and isotopic composition, the Dengli does not differ significantly from other H-chondrites. Its exposure age is 7.6 Ma. That is in agreement with common data for the exposure age (6.2 + 0.2 Ma) of 350 H-chondrites. Dengli's K/Ar age (4.01 Ga) coincides with the same ages of many other H-chondrites. Thus the Dengli is not regolithic breccia, and it probably formed during accretion of its parent body.

Ivanova, M. A.; Assonov, S. S.; Shukolyukov, Yu. A.

1993-01-01

259

A generic biokinetic model for noble gases with application to radon  

SciTech Connect

The International Commission for Radiological Protection (ICRP) currently uses a dose conversion coefficient to calculate effective dose per unit exposure to radon and its progeny. The coefficient is derived by dividing the detriment associated with unit exposure to radon, as estimated from epidemiological studies, by the detriment per unit effective dose, as estimated mainly from atomic bomb survivor data and animal studies. In a recent statement the ICRP indicated that future guidance on exposure to radon and its progeny will be developed in the same way as guidance for any other radionuclide. That is, intake of radon and progeny will be limited on the basis of effective dose coefficients derived from biokinetic and dosimetric models. This paper proposes a biokinetic model for systemic (absorbed) radon for use in the calculation of dose coefficients for inhaled or ingested radon. The model is based largely on physical laws governing transfer of a non-reactive and soluble gas between materials. Model predictions are shown to be consistent with results of controlled studies of the fate of internally deposited radon in human subjects.

Leggett, Richard Wayne [ORNL; Marsh, James [Health Protection Agency of Great Britain; Gregoratto, Demetrio [Health Protection Agency of Great Britain; Blanchardon, Eric [IRSN

2013-01-01

260

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

E-print Network

The energy associated with giant impacts is large enough to generate global magma oceans during Earth's accretion. However, geochemical evidence requiring a terrestrial magma ocean is scarce. Here we present evidence for at least two separate magma ocean outgassing episodes on Earth based on the ratio of primordial 3He to 22Ne in the present-day mantle. We demonstrate that the depleted mantle 3He/22Ne ratio is at least 10 while a more primitive mantle reservoir has a 3He/22Ne ratio of 2.3 to 3. The 3He/22Ne ratios of the mantle reservoirs are higher than possible sources of terrestrial volatiles, including the solar nebula ratio of 1.5. Therefore, a planetary process must have raised the mantle's 3He/22Ne ratio. We show that long-term plate tectonic cycling is incapable of raising the mantle 3He/22Ne ratio and may even lower it. However, ingassing of a gravitationally accreted nebular atmosphere into a magma ocean on the proto-Earth explains the 3He/22Ne and 20Ne/22Ne ratios of the primitive mantle reservoir....

Tucker, Jonathan M

2014-01-01

261

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

E-print Network

in patients with emphysema and in patients undergoing lung transplantation [2­6]. In HP gas MRI, spin and brain [1,8­12]. A special feature of HP gas MRI is that the signal-to-noise ratio (SNR) does not de

262

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

Microsoft Academic Search

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

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

2005-01-01

263

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

NASA Astrophysics Data System (ADS)

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

Gierszal, S.; Galica, J.; Mi?-Ku?mi?ska, E.

264

Groundwater dynamics and arsenic mobilization in Bangladesh assessed using noble gases and tritium.  

PubMed

The contamination of groundwater by geogenic arsenic is the cause of major health problems in south and southeast Asia. Various hypotheses proposing that As is mobilized by the reduction of iron (oxy)hydroxides are now under discussion. One important and controversial question concerns the possibility that As contamination might be related to the extraction of groundwater for irrigation purposes. If As were mobilized by the inflow of re-infiltrating irrigation water rich in labile organic carbon, As-contaminated groundwater would have been recharged after the introduction of groundwater irrigation 20-40 years ago. We used environmental tracer data and conceptual groundwater flow and transport modeling to study the effects of groundwater pumping and to assess the role of reinfiltrated irrigation water in the mobilization of As. Both the tracer data and the model results suggest that pumping induces convergent groundwater flow to the depth of extraction and causes shallow, young groundwater to mix with deep, old groundwater. The As concentrations are greatest at a depth of 30 m where these two groundwater bodies come into contact and mix. There, within the mixing zone, groundwater age significantly exceeds 30 years, indicating that recharge of most of the contaminated water occurred before groundwater irrigation became established in Bangladesh. Hence, at least at our study site, the results call into question the validity of the hypothesis that re-infiltrated irrigation water is the direct cause of As mobilization; however, the tracer data suggest that, at our site, hydraulic changes due to groundwater extraction for irrigation might be related to the mobilization of As. PMID:16433358

Klump, Stephan; Kipfer, Rolf; Cirpka, Olaf A; Harvey, Charles F; Brennwald, Matthias S; Ashfaque, Khandaker N; Badruzzaman, Abu Borhan M; Hug, Stephan J; Imboden, Dieter M

2006-01-01

265

Non-atmospheric noble gases from CO(sub 2) well ga  

NASA Technical Reports Server (NTRS)

In recent years a number of studies of both terrestrial and extraterrestrial material has allowed the piecing together of a picture of events occurring in the early solar system (4.5 Gyr ago), including the formation of the earth. However, before this picture can be completed with an appropriate amount of detail it will be necessary to make further advances. One of the areas where knowledge is lacking is the chemical and isotopic composition of the earth as a whole. The lack of knowledge has less to do with the capabilities of modern techniques than with the availability of samples to study. About 99.6 percent of the earth's mass is contained in the mantle and core, leaving less that 1 percent in the crust and atmosphere. Although the crust is derived from the mantle it has undergone extensive changes and it is therefore difficult (although not impossible) to use crustal material to study events occurring 4.5 Gyr ago. More information about the early earth could be obtained from studies of the mantle but it is difficult to obtain mantle material, because the mean thickness of the crust is 17 km, much greater than even the deepest mines or drill shafts. The two types of available mantle samples are discussed.

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

1988-01-01

266

Release of Implanted Noble Gases from Metallic Glass Vitreloy During Pyrolysis  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

267

NG09 And CTBT On-Site Inspection Noble Gas Sampling and Analysis Requirements  

NASA Astrophysics Data System (ADS)

A provision of the Comprehensive Test Ban Treaty (CTBT) allows on-site inspections (OSIs) of suspect nuclear sites to determine if the occurrence of a detected event is nuclear in origin. For an underground nuclear explosion (UNE), the potential success of an OSI depends significantly on the containment scenario of the alleged event as well as the application of air and soil-gas radionuclide sampling techniques in a manner that takes into account both the suspect site geology and the gas transport physics. UNE scenarios may be broadly divided into categories involving the level of containment. The simplest to detect is a UNE that vents a significant portion of its radionuclide inventory and is readily detectable at distance by the International Monitoring System (IMS). The most well contained subsurface events will only be detectable during an OSI. In such cases, 37 Ar and radioactive xenon cavity gases may reach the surface through either "micro-seepage" or the barometric pumping process and only the careful siting of sampling locations, timing of sampling and application of the most site-appropriate atmospheric and soil-gas capturing methods will result in a confirmatory signal. The OSI noble gas field tests NG09 was recently held in Stupava, Slovakia to consider, in addition to other field sampling and analysis techniques, drilling and subsurface noble gas extraction methods that might be applied during an OSI. One of the experiments focused on challenges to soil-gas sampling near the soil-atmosphere interface. During withdrawal of soil gas from shallow, subsurface sample points, atmospheric dilution of the sample and the potential for introduction of unwanted atmospheric gases were considered. Tests were designed to evaluate surface infiltration and the ability of inflatable well-packers to seal out atmospheric gases during sample acquisition. We discuss these tests along with some model-based predictions regarding infiltration under different near-surface hydrologic conditions. We also consider how naturally occurring as well as introduced (e.g., SF6) soil-gas tracers might be used to guard against the possibility of atmospheric contamination of soil gases while sampling during an actual OSI. The views expressed here do not necessarily reflect the opinion of the United States Government, the United States Department of Energy, or Lawrence Livermore National Laboratory. This work has been performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-418791

Carrigan, Charles R.; Tanaka, Junichi

2010-05-01

268

INCREASING THE HEAVY HYDROGEN CONTENT OF HYDROGEN  

Microsoft Academic Search

A process for increasing the heavy hydrogen content in hydrogen is ; described. A mixture of hydrogen and nitrogen is passed over a catalyst for ; ammonia synthesis. The ammonia formed is separated from the gases and replaced ; by an equivalent amount of hydrogen and nitrogen gases. This process is ; separated at least nine times. (C.E.S.)

G. Schaurer; A. Heinzel

1963-01-01

269

Noble gas storage and transport in the terrestrial mantle: the importance of grain boundaries  

NASA Astrophysics Data System (ADS)

Incompatible elements preferentially segregate to grain boundaries (GB) of mantle minerals, as opposed being dissolved in the crystal matrix, providing significant reservoirs of certain elements. Lattice strain models suggest that noble gases (NG) should be enriched in GBs [1,2]. In order to test NG partitioning between crystal and GB and to investigate diffusion of NG in grain boundaries, 4He and 40Ar were incorporated into single crystal olivine (SCO) and polycrystalline olivine with a c. 10 ?m grainsize (PCO, with grain boundaries) via annealing experiments at 300 MPa and 1150 C in a Paterson-type press. SCO and PCO were then analyzed by traditional noble gas mass spectrometry. Incremental heating of PCO identifies NG sites with different activation energies (Ea). A very low Ea Ar site (c. 0 kJ mol-1) is most probably simply adsorbed Ar. However, two higher energy sites with Ea = 50+-12 and 260+-75 kJ mol-1 are interpreted to represent grain boundary and matrix hosted Ar, respectively. Similarly, He release curves can be interpreted in terms of low energy (=GB, Ea =8+-1 kJ mol-1) and matrix (c. 175 kJ mol-1) hosted sites. The high Ea values are broadly consistent with previous measurements of matrix-hosted NG diffusivities measured by stepped heating [3, 4]. Our experiments also allow the partition coefficient between GB and matrix olivine to be measured. For He, GB/matrix is > 10^3 compared to c. 5 x10^2 for Ar. These experiments have implications for NG storage and transport in the mantle. 1) Mantle grainsize will strongly influence NG partitioning, with NG becoming less incompatible in fine grained lithologies. 2) Effective diffusion properties for fine grained aggregates will be governed by GB diffusion; diffusivities depend on poorly constrained diffusion domain sizes, but it seems likely that effective He diffusion through bulk mantle will be of the order 10^8 cm2 s-1. As a result, mantle heterogeneities less than 0.5 km will not preserve He isotopic or concentration contrasts. 3) Substantial elemental fractionation of NG could result from GB - matrix partitioning, with GB preferentially enriched in light noble gases (He, Ne).Figure. He and Ar stepped heating of polycrystalline olivine (PCO). Top = Ar, bottom = He. Solid symbols used for calculating diffusivities of grain boundaries and matrix sited He and Ar.

Burnard, P.; Demouchy, S.; Arnaud, N. O.

2012-12-01

270

Thermal expansion of noble metals using improved lattice dynamical model  

NASA Astrophysics Data System (ADS)

Isothermal bulk modulus and volume thermal expansion for noble metals have been studied on the basis of improved lattice dynamical model proposed by Pandya et al [Physica B 307, 138-149 (2001)]. The present study shows that for all three noble metals the approach gives satisfactory results, when they are compared with experimental findings. The present study thus confirms the use of improved model to study anharmonic property, and can be extended to study temperature dependent properties in high temperature range.

Kumar, Priyank; Bhatt, N. K.; Vyas, P. R.; Gohel, V. B.

2013-06-01

271

Thermal conductivity of graphene nanoribbons in noble gaseous environments  

SciTech Connect

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.

Zhong, Wei-Rong, E-mail: wrzhong@hotmail.com; Xu, Zhi-Cheng; Zheng, Dong-Qin [Department of Physics and Siyuan Laboratory, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Ai, Bao-Quan, E-mail: aibq@scnu.edu.cn [Laboratory of Quantum Information Technology, ICMP and SPTE, South China Normal University, Guangzhou 510006 (China)

2014-02-24

272

Gases: Characteristics and Properties  

NSDL National Science Digital Library

The first site related to ideal gas, called Ideal and Real Gas Laws, is maintained by Liina Ladon of Townsen University (1). Visitors can read about the properties of ideal gases, what the ideal gas law is, how to use it, and much more. The next site, titled Gas Laws, (2) is offered by the Ohio State University Department of Chemistry. This interactive site contains Shockwave movies of animations and audio files that describe what a gas is, the Ideal Gas Law equation, mixtures of gases, and problems using the ideal gas law. The University of Oregon site, Virtual Laboratory, teaches about the ideal gas law on the Welcome to the Pressure Chamber page (3). Those who enjoy online interaction will enjoy being able to control the action of a piston in a pressure chamber to see how the gases inside react. The fourth site includes another fun multimedia activity related to ideal gases provided by the Department of Physics and Astronomy at Western Washington University. The Air Filled Balloon in Liquid Nitrogen (4) movie shows an actual experiment of the effects on a balloon that's covered with liquid nitrogen. The page contains some additional information on the science behind the observations. The next site, called Ideal Gas Equations (5) is an online calculator that's part of Kean University's Department of Geology and Meteorology Web site. Users can calculate the pressure, volume, or temperature of a gas by inputting known variables into the various forms. Several methods and variations of calculating the values are provided as well as brief instructions. The next page from North Carolina State University's Basic Concepts in Environmental Science Web site is called Characteristics of Gases (6). Part of a larger learning module, the lesson plans objective is to use the ideal gas law to determine gas volumes at different absolute temperatures and absolute pressures. Everything needed to conduct the activity is provided including links to a volume calculator and practice problems. The seventh site is another animation that illustrates how gases react, called Molecular Model for an Ideal Gas (7). By changing the number of molecules in the chamber, their velocity, and the pressure and width of the container, users get to see how the molecules react to the conditions. The last site, Gases and Their Properties, is maintained by the Electronic Teaching Assistance Program(8). Students learn about the history of gas science, how gas laws describe ideal gases, what Dalton's Law and Graham's Law are, and much more.

Brieske, Joel A.

273

40 CFR 86.114-94 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

...Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles...and CO2 respectively using nitrogen as the diluent. (2) Gases...of the nominal value, using nitrogen as the diluent. (5...allowable zero gas (air or nitrogen) impurity...

2010-07-01

274

40 CFR 86.1314-94 - Analytical gases.  

Code of Federal Regulations, 2012 CFR

...Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines...CO2 . respectively, using nitrogen as the diluent. (b) Gases...of the nominal value using nitrogen as the diluent. (e...allowable zero gas (air or nitrogen) impurity...

2012-07-01

275

40 CFR 86.114-94 - Analytical gases.  

...Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles...and CO2 respectively using nitrogen as the diluent. (2) Gases...of the nominal value, using nitrogen as the diluent. (5...allowable zero gas (air or nitrogen) impurity...

2014-07-01

276

40 CFR 86.1314-94 - Analytical gases.  

Code of Federal Regulations, 2011 CFR

...Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines...CO2 . respectively, using nitrogen as the diluent. (b) Gases...of the nominal value using nitrogen as the diluent. (e...allowable zero gas (air or nitrogen) impurity...

2011-07-01

277

40 CFR 86.114-94 - Analytical gases.  

Code of Federal Regulations, 2012 CFR

...Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles...and CO2 respectively using nitrogen as the diluent. (2) Gases...of the nominal value, using nitrogen as the diluent. (5...allowable zero gas (air or nitrogen) impurity...

2012-07-01

278

40 CFR 86.1314-94 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

...Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines...CO2 . respectively, using nitrogen as the diluent. (b) Gases...of the nominal value using nitrogen as the diluent. (e...allowable zero gas (air or nitrogen) impurity...

2010-07-01

279

40 CFR 86.1314-94 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

...Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines...CO2 . respectively, using nitrogen as the diluent. (b) Gases...of the nominal value using nitrogen as the diluent. (e...allowable zero gas (air or nitrogen) impurity...

2013-07-01

280

40 CFR 86.114-94 - Analytical gases.  

Code of Federal Regulations, 2013 CFR

...Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles...and CO2 respectively using nitrogen as the diluent. (2) Gases...of the nominal value, using nitrogen as the diluent. (5...allowable zero gas (air or nitrogen) impurity...

2013-07-01

281

40 CFR 86.114-94 - Analytical gases.  

Code of Federal Regulations, 2011 CFR

...Light-Duty Trucks and New Otto-Cycle Complete Heavy-Duty Vehicles...and CO2 respectively using nitrogen as the diluent. (2) Gases...of the nominal value, using nitrogen as the diluent. (5...allowable zero gas (air or nitrogen) impurity...

2011-07-01

282

Underground Sources of Radioactive Noble Gas  

SciTech Connect

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.

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

283

Modeling Noble Gas Transport and Detection for The Comprehensive Nuclear-Test-Ban Treaty  

NASA Astrophysics Data System (ADS)

Detonation gases released by an underground nuclear test include trace amounts of 133Xe and 37Ar. In the context of the Comprehensive Nuclear Test Ban Treaty, On Site Inspection Protocol, such gases released from or sampled at the soil surface could be used to indicate the occurrence of an explosion in violation of the treaty. To better estimate the levels of detectability from an underground nuclear test (UNE), we developed mathematical models to evaluate the processes of 133Xe and 37Ar transport in fractured rock. Two models are developed respectively for representing thermal and isothermal transport. When the thermal process becomes minor under the condition of low temperature and low liquid saturation, the subsurface system is described using an isothermal and single-gas-phase transport model and barometric pumping becomes the major driving force to deliver 133Xe and 37Ar to the ground surface. A thermal test is simulated using a nonisothermal and two-phase transport model. In the model, steam production and bubble expansion are the major processes driving noble gas components to ground surface. After the temperature in the chimney drops below boiling, barometric pumping takes over the role as the major transport process.

Sun, Yunwei; Carrigan, Charles R.

2014-03-01

284

Gases in Tektite Bubbles.  

PubMed

Spectroscopic analysis of light produced by electrodeless discharge in a tektite bubble showed the main gases in the bubble to be neon, helium, and oxygen. The neon and helium have probably diffused in from the atmosphere, while the oxygen may be atmospheric gas incorporated in the tektite during its formation. PMID:17801113

O'keefe, J A; Lowman, P D; Dunning, K L

1962-07-20

285

Properties of Copper Cavities Coated with Niobium Using Different Discharge Gases  

E-print Network

Experimental evidence is presented showing that in conformity with theoretical expectations, discharge gas atoms are trapped in sputtered films whenever a gas of atomic mass smaller than that of the c athode is used. In such a case, discharge gas atoms may be reflected by the cathode as high energy neutrals and get incorporated in the growing film. Niobium films have been produced using Ne, Ar, Kr, Xe and then analysed for rare gas content by thermal extraction. The gas concentrations are found to vary from the several percent range for Ne down to the ppm level for Kr and Xe. The noble gas conce ntration in the film influences the RRR and, in the case of high concentration, also the critical temperature. To study the effect of the implanted noble gas on the superconducting RF parameters, seve ral 1.5 GHz copper cavities have been niobium-coated using the different discharge gases. The noble gases trapped in the film affect the penetration depth, the temperature dependent losses (RBCS), the losses induced by t...

Benvenuti, Cristoforo; Campisi, I E; Darriulat, Pierre; Marino, M; Peck, M A; Russo, R; Valente, A M

1997-01-01

286

Catalytic Generation of Lift Gases for Balloons  

NASA Technical Reports Server (NTRS)

A lift-gas cracker (LGC) is an apparatus that generates a low-molecular-weight gas (mostly hydrogen with smaller amounts of carbon monoxide and/or carbon dioxide) at low gauge pressure by methanol reforming. LGCs are undergoing development for use as sources of buoyant gases for filling zero-gauge-pressure meteorological and scientific balloons in remote locations where heavy, high-pressure helium cylinders are not readily available. LGCs could also be used aboard large, zero-gauge-pressure, stratospheric research balloons to extend the duration of flight.

Zubrin, Robert; Berggren, Mark

2011-01-01

287

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

288

Dual mechanism of ion beam mixing of noble metals with oxide matrices  

NASA Astrophysics Data System (ADS)

Layers of noble metals M embedded in various oxide matrices (SiO2, Al2O3, TiO2, ZrO2, and also Si for a purpose of comparison) were irradiated with incremented fluences of MeV heavy ions. A major contribution of recoil implantation to displacements accounts for the linear rates of atoms relocation as a function of the ion fluence, measured by means of RBS. According to the temperature and to the initial thickness of the M layer, the in depth-straggling of M atoms varies in proportion to the ion fluence or to its square. This change of straggling rate is explained by its control either by the radiation-enhanced diffusion or by the recoil implantation process, when the solution of diffusion equations relative to an infinitely thin source cannot be applied. The mobility of M atoms in the oxide depends on the latter ionicity and on the M mass.

Pivin, J. C.; Rizza, G.

2000-05-01

289

Developments in Noble Gas mass spectrometry  

NASA Astrophysics Data System (ADS)

D. HAMILTON*, J.B. SCHWIETERS, D. TUTTAS, M. KRUMMEN, M. DEERBERG, N.S. LLOYD1 1Thermo Fisher Scientific, Hanna-Kunath-Str. 11, 28199 Bremen, Germany (*correspondence: Doug.Hamilton@ThermoFisher.com) Recent advances in ion optics and electronic design have added features to the new range of Noble Gas mass spectrometers from Thermo Fisher Scientific that will enable the scientific community to resolve a number of existing analytical limitations. The first development relates to detector technology. Because instrument transmission and ion source efficiency can be very high, detector noise can be the limiting factor for ultra-small sample analysis. Faraday cup detectors are the detectors of choice for high accuracy and high precision isotope ratio measurements because of their unmatched stability and linearity and because of the electronic cross calibration network available to precisely and accurately cross calibrate the multiple Faraday detector channels against each other. Today, most IOMS systems are equipped with current amplifiers using a 1011 Ohm resistor coupled to the feedback loop of a high stability and temperature-stabilized operational amplifier. In this paper we will describe our latest investigations in Faraday cup measurements utilising 1012 & 1013 resistors for signal intensities in the range of 1 pA to 1 fA. The second development relates to a new beam deflection technology added to the ARGUS VI mass spectrometer that enables a fixed collector array to be given some of the properties of a mechanically adjustable array. This enables multidynamic multicollector measurements to be taken utilising a fixed array thus enabling the end user to perform vital detector crosscalibrations “in run”. Lastly we will describe early results on a new high resolution platform and the capabilities of this platform to finally deal with certain isotopic interferences in both the Argon and Neon spectra.

Hamilton, D.; Schwieters, J. B.; Lloyd, N. S.

2010-12-01

290

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

SciTech Connect

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

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

2010-08-15

291

Aptamer functionalized noble metal particles for bioanalytical and biomedical applications  

NASA Astrophysics Data System (ADS)

Noble metal particles, especially gold (Au) and silver (Ag) have been exploited in a broad range of biological applications due to their unique intrinsic features that depend on their physical appearance or optoelectronic properties, which can be tuned with the change in the size or shape of those particles. Thus, this tunability enables gold nanoparticles (AuNPs) to be used in biomedical diagnostic and therapeutical applications. In photothermal therapy applications, nanomaterials, which can absorb efficiently in NIR region, are utilized since the healthy tissue or cells can't absorb at this spectral region. Among AuNPs, gold nanorods (AuNRs) are one of the best candidates for hyperthermia therapy of cancer cells with their high absorption cross-sections and tunable absorption maxima in NIR region. When this unique optical property is combined with the specificity against cancer cells utilized by aptamer conjugations, AuNRs become to be one of the most important nanoparticles employed in both cancer cell sensing and therapy. However, one drawback of AuNRs is having the surfactant CTAB on their surface, which can cause nonspecificity and cytotoxicity. In this research, the side effects of CTAB are passivated by BSA modification, where the nonspecificity and cytotoxicity are dramatically decreased prior to the NIR treatment. Recognition of changes in the rare cancer protein abundances can lead the early diagnosis of cancer, so capturing these low abundance proteins has a great significance. In this research, firstly, aptamer conjugated AuNRs were used to capture 1ng of a-thrombin effectively from plasma samples as model system. Then both aptamer conjugated AuNRs and silver microspheres (SMSs) are used to capture the biomarker proteins of a colon cancer cell line, DLD-1. Gold and silver surfaces can easily be modified through thiolate chemistry, compared to the tedious modification steps for the magnetic particles, so more aptamer immobilization can be achieved for AuNRs and SMSs, which can increase the possibility of binding to the target protein. Furthermore, SMSs offer a novel separation method, gravitational separation owing to their heavy nature. In this way, there is no need for an external stimuli to separate the captured proteins and protein isolation can take only seconds.

Yasun, Emir

292

Greenhouse Gases Exposed  

NSDL National Science Digital Library

In this activity, students learn about the relationship between greenhouse gases and global warming through a simple teacher demo or hands-on lab activity. Everyday materials are used: beakers, baking soda, vinegar, candle, thermometers, heat source such as a goose-necked lamp, etc. Students shine a light onto three thermometers: a control, an upside down beaker w/ a thermometer and air, and a beaker in which CO2 had been poured.

Victoria Babcock

293

Supercontinuum generation in gases  

Microsoft Academic Search

Supercontinua extending from the ultraviolet to the infrared are observed from high-pressure (1-40 atm) Ar, Kr, Xe, H2, or CO2 illuminated with 2-psec or 70-fsec, 0.6-micron pulses with an energy of less than about 500 micro J. The blue spectral component is shown to display a nearly universal behavior for all gases and pulse durations. Although the maximum intensity of

P. B. Corkum; Claude Rolland; T. Srinivasan-Rao

1986-01-01

294

A search for noble-gas evidence for presolar oxide grains  

NASA Technical Reports Server (NTRS)

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.

Lewis, Roy S.; Srinivasan, B.

1993-01-01

295

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

NASA Astrophysics Data System (ADS)

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 precursors for major seismic events in the region of Lake Van, as shown for the case of the recent magnitude 7.2 earthquake, with a potential forecast time of one year.

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

2013-12-01

296

Molecular dynamics prediction of density for metastable liquid noble metals  

NASA Astrophysics Data System (ADS)

The thermophysical properties of metastable liquid noble metals are not readily available due to the great experimental difficulties. Here the densities of liquid Pd, Pt, Ag, and Au are predicted by molecular dynamics method. The pair distribution functions are computed to monitor the atomic structure of these noble metals, which indicate that the systems remain in liquid state in the process of simulation. The calculated densities exhibit nonlinear temperature dependences and prove to have a high accuracy. The density data are obtained in a much broader temperature range, especially in the undercooled regime. Moreover, the molar volumes and the thermal expansion coefficients are also derived from the density predictions.

Wang, H. P.; Yang, S. J.; Wei, B.

2012-06-01

297

Isotopic mass-dependence of noble gas diffusion coefficients inwater  

SciTech Connect

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.

Bourg, I.C.; Sposito, G.

2007-06-25

298

Polyacrylonitrile/noble metal/SiO2 nanofibers as substrates for the amplified detection of picomolar amounts of metal ions through plasmon-enhanced fluorescence  

NASA Astrophysics Data System (ADS)

Electrospun polymer/noble metal hybrid nanofibers have developed rapidly as surface-enhanced Raman scattering (SERS)-active substrates over the last few years. However, polymer/noble metal nanofibers with plasmon-enhanced fluorescence (PEF) activity have received no attention to date. Herein, we show a general and facile approach for the preparation of polyacrylonitrile (PAN)/noble metal/SiO2 nanofibrous mats with PEF activity for the first time by combining electrospinning and controlled silica coatings. These PEF-active nanofibrous mats can selectively improve the fluorescence intensity of conjugated polyelectrolytes (CPEs). Importantly, the CPE solution in the presence of a PAN/noble metal/SiO2 nanofibrous mat showed dramatic fluorescence quenching towards picomolar (pM) amounts of heavy metal ions, while the fluorescence of the CPE solution without the nanofibrous mat had no apparent quenching towards micromolar (?M) amounts of metal ions. The combination of the distance-dependent fluorescence enhancement performance of metal NPs and the ionic characteristics of the CPE solution makes the polymer/noble metal nanofibers promising substrates for greatly improving the detection sensitivity towards metal ions. We believe that this work provides a general strategy for preparing plasmon band-tuned PEF-active substrates with advantages including good selectivity, remarkable sensitivity and recyclability, which make them a preferable choice for practical sensing applications.Electrospun polymer/noble metal hybrid nanofibers have developed rapidly as surface-enhanced Raman scattering (SERS)-active substrates over the last few years. However, polymer/noble metal nanofibers with plasmon-enhanced fluorescence (PEF) activity have received no attention to date. Herein, we show a general and facile approach for the preparation of polyacrylonitrile (PAN)/noble metal/SiO2 nanofibrous mats with PEF activity for the first time by combining electrospinning and controlled silica coatings. These PEF-active nanofibrous mats can selectively improve the fluorescence intensity of conjugated polyelectrolytes (CPEs). Importantly, the CPE solution in the presence of a PAN/noble metal/SiO2 nanofibrous mat showed dramatic fluorescence quenching towards picomolar (pM) amounts of heavy metal ions, while the fluorescence of the CPE solution without the nanofibrous mat had no apparent quenching towards micromolar (?M) amounts of metal ions. The combination of the distance-dependent fluorescence enhancement performance of metal NPs and the ionic characteristics of the CPE solution makes the polymer/noble metal nanofibers promising substrates for greatly improving the detection sensitivity towards metal ions. We believe that this work provides a general strategy for preparing plasmon band-tuned PEF-active substrates with advantages including good selectivity, remarkable sensitivity and recyclability, which make them a preferable choice for practical sensing applications. Electronic supplementary information (ESI) available: TEM and SEM images of PAN/Ag/SiO2 nanofibers with different thicknesses; molecular structures and fluorescence spectra of five dyes; normalized extinction spectra of PAN/Ag0.8Au0.2/SiO2 nanofibrous mats; photos of the PAN/Ag/SiO2 nanofibrous mat. See DOI: 10.1039/c4nr05349d

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

2015-01-01

299

Size-dependent melting point of noble metals  

Microsoft Academic Search

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

Q. Jiang; S. Zhang; M. Zhao

2003-01-01

300

NUCLEAR GENERATED PLASMAS IN NOBLE GAS THERMIONIC CONVERTERS  

Microsoft Academic Search

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

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

1963-01-01

301

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

302

Nuclear Magnetic Resonance Experiments using Laser-Polarized Noble Gas  

E-print Network

Patrick Teen Chung Wong to The Department of Physics in partial fulfillment of the requirements 2001 #12;c 2001 by Glenn Patrick Teen Chung Wong All rights reserved #12;Advisor: Dr. Ronald Walsworth Author: Glenn Patrick Teen Chung Wong Nuclear Magnetic Resonance Experiments using Laser-Polarized Noble

Walsworth, Ronald L.

303

The Origin of Noble Gas Isotopic Heterogeneity in Icelandic Basalts  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

304

Synthesis and characterization of fluorescence-labelled silica core-shell and noble metal-decorated ceria nanoparticles  

PubMed Central

Summary The present review article covers work done in the cluster NPBIOMEM in the DFG priority programme SPP 1313 and focuses on synthesis and characterization of fluorescent silica and ceria nanoparticles. Synthetic methods for labelling of silica and polyorganosiloxane/silica core–shell nanoparticles with perylenediimide derivatives are described, as well as the modification of the shell with thiol groups. Photometric methods for the determination of the number of thiol groups and an estimate for the number of fluorescent molecules per nanoparticles, including a scattering correction, have been developed. Ceria nanoparticles decorated with noble metals (Pt, Pd, Rh) are models for the decomposition products of automobile catalytic converters which appear in the exhaust gases and finally interact with biological systems including humans. The control of the degree of agglomeration of small ceria nanoparticles is the basis for their synthesis. Almost monodisperse agglomerates (40 ± 4–260 ± 40 nm diameter) can be prepared and decorated with noble metal nanoparticles (2–5 nm diameter). Fluorescence labelling with ATTO 647N gave the model particles which are now under biophysical investigation. PMID:25671137

Rennhak, Markus; Reller, Armin

2014-01-01

305

The effect of the negative pressure of capillary water on atmospheric noble gas solubility in ground water and palaeotemperature reconstruction  

NASA Astrophysics Data System (ADS)

Atmospheric-derived noble gases He, Ne, Ar, Kr and Xe dissolved in ground waters record the temperature at the moment of their recharge. Palaeotemperature reconstructions should include all the parameters affecting the soil air-ground water thermodynamic equilibrium. Particularly, the occurrence of excess air, that is ANG in excess compared to the equilibrium concentrations and often mass-fractionated compared to the atmospheric pattern, is likely produced by air entrapment during water infiltration in the nonsaturated zone (NSZ). Here, we show that water persisting in the NSZ has peculiar capillary properties controlled by the internal water pressure, which decreases (even down to negative pressures) with decreasing soil-air humidity. Decreasing water pressure induces mass-dependent increasing solubility of ANG from He to Xe. In addition, in nonsaturated soils where water and air coexist, air entrapment is favored allowing nonfractionated excess air. This capillary approach has been coded in an inverse-method program called Thermo_Inver, and tested on two well-characterized noble gas datasets used to constrain palaeotemperatures in Midwestern United States and Brazil during the last glacial maximum [Quat. Res. 43 (1995) 209; Science 269 (1995) 379]. Results of these simulations highlight that under suitable climatic conditions and in fine-porous media, the capillary pressure of water may be a prominent parameter controlling the addition of ANG to ground waters. Under these conditions, the recharge zone for ANG is the NZS and this water-air coexistence zone easily produces excess air.

Mercury, Lionel; Pinti, Daniele L.; Zeyen, Hermann

2004-06-01

306

Synthesis and characterization of fluorescence-labelled silica core-shell and noble metal-decorated ceria nanoparticles.  

PubMed

The present review article covers work done in the cluster NPBIOMEM in the DFG priority programme SPP 1313 and focuses on synthesis and characterization of fluorescent silica and ceria nanoparticles. Synthetic methods for labelling of silica and polyorganosiloxane/silica core-shell nanoparticles with perylenediimide derivatives are described, as well as the modification of the shell with thiol groups. Photometric methods for the determination of the number of thiol groups and an estimate for the number of fluorescent molecules per nanoparticles, including a scattering correction, have been developed. Ceria nanoparticles decorated with noble metals (Pt, Pd, Rh) are models for the decomposition products of automobile catalytic converters which appear in the exhaust gases and finally interact with biological systems including humans. The control of the degree of agglomeration of small ceria nanoparticles is the basis for their synthesis. Almost monodisperse agglomerates (40 ± 4-260 ± 40 nm diameter) can be prepared and decorated with noble metal nanoparticles (2-5 nm diameter). Fluorescence labelling with ATTO 647N gave the model particles which are now under biophysical investigation. PMID:25671137

Herrmann, Rudolf; Rennhak, Markus; Reller, Armin

2014-01-01

307

(Desulfurization of fuel gases)  

SciTech Connect

The objective of this work was to demonstrate that solid solutions of cerium oxide (CeO{sub 2}) and other altervalent oxides (doped CeO{sub 2}) were capable of removing more H{sub 2}S from fuel gases than Ceo{sub 2} without any dopant. The ability of undoped CeO{sub 2} to remove H{sub 2}S from fuel gases had been determined with a previous DOE/SBIR grant. To make the results obtained under the two grants comparable, the procedures for all phases of this work duplicated that used previously as closely as possible. The sorbents GDC proposed to investigate were: (1) undoped CeO{sub 2}, (2) CeO{sub 2} doped with 5 mole % (5 m/o) magnesium oxide (MgO), and (3) CeO{sub 2} doped with 5 m/o lanthanum oxide (La{sub 2}O{sub 3}). Three additional sorbents: (1) CeO{sub 2} doped with 5 m/o strontium oxide (SrO), (2) CeO{sub 2} doped with 10 m/o SrO, and (2) CeO{sub 2} doped with 10 m/o La{sub 2}O{sub 3} were also investigated. All of these sorbents were prepared using the Marcilly technique.

Not Available

1991-12-15

308

Noble gas component organization in Apollo 14 breccia 14318: /sup 129/I and /sup 244/Pu regolith chronology  

SciTech Connect

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.

Swindle, T.D.; Caffee, M.W.; Hohenberg, C.M.; Hudson, G.B.; Laul, J.C.; Simon, S.B.; Papike, J.J.

1985-02-15

309

Control of pollutants in flue gases and fuel gases  

E-print Network

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.2 Flue gases and fuel gases: combustion, gasification, pyrolysis, incineration and other and gasification technologies for heat and power . . . . . . . . 2-3 2.4 Waste incineration and waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3.3 Formation of sulphur compounds during combustion and gasification . . 3-5 3.4 Emission

Zevenhoven, Ron

310

Control of pollutants in flue gases and fuel gases  

E-print Network

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.2 Flue gases and fuel gases: combustion, gasification, pyrolysis, incineration and other and gasification technologies for heat and power . . . . . . . . 2-3 2.4 Waste incineration and waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3.3 Formation of sulphur compounds during combustion and gasification . 3-5 3.4 Emission

Laughlin, Robert B.

311

Method for removing acid gases from a gaseous stream  

DOEpatents

In a process for hydrocracking a heavy aromatic polynuclear carbonaceous feedstock containing reactive alkaline constituents to produce liquid hydrocarbon fuels boiling below about 475.degree. C. at atmospheric pressure by contacting the feedstock with hydrogen in the presence of a molten metal halide catalyst, thereafter separating a gaseous stream containing hydrogen, at least a portion of the hydrocarbon fuels and acid gases from the molten metal halide and regenerating the molten metal halide, thereby producing a purified molten metal halide stream for recycle to the hydrocracking zone, an improvement comprising; contacting the gaseous acid gas, hydrogen and hydrocarbon fuels-containing stream with the feedstock containing reactive alkaline constituents to remove acid gases from the acid gas containing stream. Optionally at least a portion of the hydrocarbon fuels are separated from gaseous stream containing hydrogen, hydrocarbon fuels and acid gases prior to contacting the gaseous stream with the feedstock.

Gorin, Everett (San Rafael, CA); Zielke, Clyde W. (McMurray, PA)

1981-01-01

312

Ground-Water Temperature, Noble Gas, and Carbon Isotope Data from the Espanola Basin, New Mexico  

USGS Publications Warehouse

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.

Manning, Andrew H.

2009-01-01

313

The Role of Boron-Chloride and Noble Gas Isotope Ratios in TVZ Geothermal Systems  

SciTech Connect

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.

Hulston, J.R.

1995-01-01

314

Kinetic Molecular Theory of Gases  

NSDL National Science Digital Library

Applets dealing with the meaning of the Maxwell distribution of gases and pressure of gases are discussed. The Maxwell distribution experiment allow the user to explore the most probable speed of gas molecules. The pressure experiment allows the user to explore the effects of size and mass on collision rate, direction, and relative speed of gas molecules within a fixed volume.

David N. Blauch

315

Greenhouse Gases: A Closer Look  

NSDL National Science Digital Library

This lesson covers different aspects of the major greenhouse gases - water vapor, carbon dioxide, methane, nitrous oxides and CFCs - including some of the ways in which human activities are affecting the atmospheric concentrations of these key greenhouse gases. This is lesson six in a nine-lesson module about climate change.

King's Centre for Visualization in Science

316

Voluntary Reporting of Greenhouse Gases  

EIA Publications

The Voluntary Reporting of Greenhouse Gases Program was suspended May 2011. It was a mechanism by which corporations, government agencies, individuals, voluntary organizations, etc., could report to the Energy Information Administration, any actions taken that have or are expected to reduce/avoid emissions of greenhouse gases or sequester carbon.

2011-01-01

317

New evidence for chondritic lunar water from combined D/H and noble gas analyses of single Apollo 17 volcanic glasses  

NASA Astrophysics Data System (ADS)

In order to assess the proportion of solar, cosmogenic, and indigenous water (hydrogen) trapped in individual Ti-rich lunar volcanic glasses (LVGs) from the 74002 core obtained during the Apollo 17 mission, we coupled ion microprobe measurements of water abundances and D/H ratios with CO2 laser extraction-static mass spectrometry analyses of noble gases (He, Ne, Ar). The large (?300-400 ?m in diameter) LVGs studied here contain a small amount of solar wind (SW) volatiles implanted at the grain surfaces, as indicated by the small concentrations of solar helium and neon that represent ?5% of the respective total noble gas abundances. The large proportion of volume-correlated cosmogenic gases reflects an exposure duration of ?28 Ma, on average, of the glasses at the lunar surface. Hydrogen abundances determined in the grain interiors of glassy and partially-crystalline LVGs are equivalent to between 6.5 and 54.3 ppm H2O. Based on the noble gas exposure ages, the correction of the measured hydrogen isotope composition for in situ production of cosmogenic deuterium by spallation reactions varies between -5‰ to -254‰ for the different grains. Corrected ?D values range from +38‰ to +809‰ in the LVGs and are anti-correlated with the water content, consistent with extensive hydrogen isotope fractionation during kinetic H2 loss from a lunar melt with an inferred initial isotope signature of the order of -100‰ and a water content of 100-300 ppm. The detection of water in these primitive lunar melts confirms the presence of a non-anhydrous mantle reservoir within the Moon. Furthermore, our results reveal that the hydrogen isotope composition of water in the melt source of the 74002 LVGs is similar to that of carbonaceous chondrites. These observations indicate that the contribution of deuterium-enriched cometary water to the Earth-Moon system is negligible.

Füri, Evelyn; Deloule, Etienne; Gurenko, Andrey; Marty, Bernard

2014-02-01

318

Control of acid gases using a fluidized bed adsorber.  

PubMed

During incineration, secondary pollutants such as acid gases, organic compounds, heavy metals and particulates are generated. Among these pollutants, the acid gases, including sulfur oxides (SO(x)) and hydrogen chloride (HCl), can cause corrosion of the incinerator piping and can generate acid rain after being emitted to the atmosphere. To address this problem, the present study used a novel combination of air pollution control devices (APCDs), composed of a fluidized bed adsorber integrated with a fabric filter. The major objective of the work is to demonstrate the performance of a fluidized bed adsorber for removal of acid gases from flue gas of an incinerator. The adsorbents added in the fluidized bed adsorber were mainly granular activated carbon (AC; with or without chemical treatment) and with calcium oxide used as an additive. The advantages of a fluidized bed reactor for high mass transfer and high gas-solid contact can enhance the removal of acid gases when using a dry method. On the other hand, because the fluidized bed can filter particles, fine particles prior to and after passing through the fluidized bed adsorber were investigated. The competing adsorption on activated carbon between different characteristics of pollutants was also given preliminary discussion. The results indicate that the removal efficiencies of the investigated acid gases, SO(2) and HCl, are higher than 94 and 87%, respectively. Thus, a fluidized bed adsorber integrated with a fabric filter has the potential to replace conventional APCDs, even when there are other pollutants at the same time. PMID:12935758

Chiang, Bo-Chin; Wey, Ming-Yen; Yeh, Chia-Lin

2003-08-01

319

Low-field MRI of laser polarized noble gas  

NASA Technical Reports Server (NTRS)

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.

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

320

Noble gas radionuclides in RBMK-1500-type reactor  

Microsoft Academic Search

The presence of noble gas and other short-lived radionuclides in air borne effluents from RBMK-1500-type reactor has been investigated using experimental and theoretical instrumentation for detection purposes. Activity concentrations of 85mKr, 87Kr, 88Kr, 135mXe, 135Xe, 133Xe and 41Ar were measured in air emissions from Ignalina NPP using a special method and special equipment. Theoretical detection of reactor-borne radionuclides and investigation

Rimvydas Jasiulionis; Gediminas Adlys; Diana Adliene; Linas Vy?inas

2007-01-01

321

Resonance ionization spectroscopy: counting noble-gas atoms  

SciTech Connect

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.

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

1981-06-01

322

Possible solar noble-gas component in Hawaiian basalts  

USGS Publications Warehouse

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.

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

1991-01-01

323

Noble gas radionuclides in RBMK-1500-type reactor.  

PubMed

The presence of noble gas and other short-lived radionuclides in air borne effluents from RBMK-1500-type reactor has been investigated using experimental and theoretical instrumentation for detection purposes. Activity concentrations of (85m)Kr, (87)Kr, (88)Kr, (135m)Xe, (135)Xe, (133)Xe and (41)Ar were measured in air emissions from Ignalina NPP using a special method and special equipment. Theoretical detection of reactor-borne radionuclides and investigation of their behaviour in a nuclear fuel during operation of nuclear reactor was performed using an analytical model based on reactor physics. An innovative method for the estimation of noble gas flow time from the defective nuclear fuel element through the ventilation stack of NPP to the atmosphere based on comparison of the experimentally and theoretically evaluated activity ratios of (88)Kr/(85m)Kr; (135)Xe/(133)Xe has been proposed. The estimated flow time of noble gas provides an excellent possibility to obtain modelling-based information about the qualitative and quantitative content of atmospheric releases from NPP. PMID:17383886

Jasiulionis, Rimvydas; Adlys, Gediminas; Adliene, Diana; Vycinas, Linas

2007-07-01

324

Feshbach resonances in ultracold gases  

SciTech Connect

Feshbach resonances are the essential tool to control the interaction between atoms in ultracold quantum gases. They have found numerous experimental applications, opening up the way to important breakthroughs. This review broadly covers the phenomenon of Feshbach resonances in ultracold gases and their main applications. This includes the theoretical background and models for the description of Feshbach resonances, the experimental methods to find and characterize the resonances, a discussion of the main properties of resonances in various atomic species and mixed atomic species systems, and an overview of key experiments with atomic Bose-Einstein condensates, degenerate Fermi gases, and ultracold molecules.

Chin Cheng; Grimm, Rudolf; Julienne, Paul; Tiesinga, Eite [Department of Physics and James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States); Center for Quantum Physics and Institute of Experimental Physics, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck (Austria) and Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Otto-Hittmair-Platz 1, 6020 Innsbruck (Austria); Joint Quantum Institute, National Institute of Standards and Technology and University of Maryland, 100 Bureau Drive, Gaithersburg, Maryland 20899-8423 (United States)

2010-04-15

325

Environmental implications of anesthetic gases.  

PubMed

For several decades, anesthetic gases have greatly enhanced the comfort and outcome for patients during surgery. The benefits of these agents have heavily outweighed the risks. In recent years, the attention towards their overall contribution to global climate change and the environment has increased. Anesthesia providers have a responsibility to minimize unnecessary atmospheric pollution by utilizing techniques that can lessen any adverse effects of these gases on the environment. Moreover, health care facilities that use anesthetic gases are accountable for ensuring that all anesthesia equipment, including the scavenging system, is effective and routinely maintained. Implementing preventive practices and simple strategies can promote the safest and most healthy environment. PMID:23241038

Yasny, Jeffrey S; White, Jennifer

2012-01-01

326

Investigating and Using Biomass Gases  

NSDL National Science Digital Library

In this activity, learners will be introduced to biomass gasification and will generate their own biomass gases. Learners generate these gases everyday on their own and find it quite amusing, but this time theyâll do it by heating wood pellets or wood splints in a test tube. They will collect the resulting gases and use the gas to roast a marshmallow. Learners will also evaluate which biomass fuel is the best either according to their own criteria or by examining the volume of gas produced by each type of fuel.

Benson, Eric; Highfill, Melissa

2012-07-03

327

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

NASA Astrophysics Data System (ADS)

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.

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

2012-05-01

328

Degenerate quantum gases of strontium  

E-print Network

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

Stellmer, Simon; Killian, Thomas C

2013-01-01

329

Noble Metals and Spinel Settling in High Level Waste Glass Melters  

SciTech Connect

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

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

2000-09-30

330

Direct synthesis of noble metal/graphene nanocomposites from graphite in water: photo-synthesis.  

PubMed

We report on the direct and facile method for noble metal/graphene nano-composites from graphite without reducing agents. In this system, the irradiant white-light instead of the chemical reducing agent exerts the influence on the synthesis of noble metal nanoparticles on graphene. Noble metal salts adsorbed on graphene flakes which were functionalized with ionic surfactants were reduced by irradiation with white light. In particular, noble metal nanoparticles were more evenly distributed on the surface of graphene which was functionalized with SDS than with CTAB. PMID:22002017

Jeong, Gyoung Hwa; Kim, Seung Hyun; Kim, Minjeong; Choi, Donghyeuk; Lee, Jae Hyeok; Kim, Jae-Ho; Kim, Sang-Wook

2011-11-28

331

Inert anode containing base metal and noble metal useful for the electrolytic production of aluminum  

DOEpatents

An inert anode for production of metals such as aluminum is disclosed. The inert anode comprises a base metal selected from Cu and Ag, and at least one noble metal selected from Ag, Pd, Pt, Au, Rh, Ru, Ir and Os. The inert anode may optionally be formed of sintered particles having interior portions containing more base metal than noble metal and exterior portions containing more noble metal than base metal. In a preferred embodiment, the base metal comprises Cu, and the noble metal comprises Ag, Pd or a combination thereof.

Ray, Siba P. (Murrysville, PA); Liu, Xinghua (Monroeville, PA)

2000-01-01

332

REMOVAL OF SLIGHTLY HEAVY GASES FROM A VALLEY BY CROSSWINDS  

EPA Science Inventory

Wind-tunnel experiments made to determine how rapidly dense gas is removed from a topographical depression by a crosswind are reported. he density and flow rate of the gas (input at the bottom of a V-shaped valley in otherwise homogeneous, flat terrain)were together sufficiently ...

333

Measurements of relative photoemission time delays in noble gas atoms  

NASA Astrophysics Data System (ADS)

We determine relative photoemission time delays between valence electrons in different noble gas atoms (Ar, Ne and He) in an energy range between 31 and 37 eV. The atoms are ionized by an attosecond pulse train synchronized with an infrared laser field and the delays are measured using an interferometric technique. We compare our results with calculations using the random phase approximation with exchange and multi-configurational Hartree–Fock. We also investigate the influence of the different ionization angular channels. .

Guénot, D.; Kroon, D.; Balogh, E.; Larsen, E. W.; Kotur, M.; Miranda, M.; Fordell, T.; Johnsson, P.; Mauritsson, J.; Gisselbrecht, M.; Varjù, K.; Arnold, C. L.; Carette, T.; Kheifets, A. S.; Lindroth, E.; L?Huillier, A.; Dahlström, J. M.

2014-12-01

334

Surface reconstruction of noble metals; Models and consequences  

SciTech Connect

This paper reviews work on the theory of noble metal surface reconstructions. We put strong emphasis on gold, chosen as a representative prototype system, and discuss in detail its three main faces, Au(100), (110) and (111), a class of (100) vicinals and small clusters. In particular, we discuss the microscopic modeling of these surfaces via a particular many-particle classical Hamiltonian, the so-called glue model, which we have developed in Trieste. Optimal surface structures, obtained by molecular dynamics annealing, are amusingly rich, and can explain several facts known from experiment.

Tosatti, E.; Ercolessi, F. (International School for Advanced Studies, Via Beirut 4, I-34014 Trieste (IT))

1992-01-01

335

Mechanical response of noble gas films to an oscillating substrate  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

336

Nanoparticles of noble metals in the supergene zone  

NASA Astrophysics Data System (ADS)

Formation of noble metal nanoparticles is related to various geological processes in the supergene zone. Dispersed mineral phases appear during weathering of rocks with active participation of microorganisms, formation of soil, in aqueous medium and atmosphere. Invisible gold and other noble metals are incorporated into oxides, hydroxides, and sulfides, as well as in dispersed organic and inorganic carbonic matter. Sulfide minerals that occur in bedrocks and ores unaltered by exogenic processes and in cementation zone are among the main concentrators of noble metal nanoparticles. The ability of gold particles to disaggregate is well-known and creates problems in technological and analytical practice. When Au and PGE nanoparticles and clusters occur, these problems are augmented because of their unusual reactions and physicochemical properties. The studied gold, magnetite, titanomagnetite and pyrite microspherules from cementation zone and clay minerals of laterites in Republic of Guinea widen the knowledge of their abundance and inferred formation conditions, in particular, in the contemporary supergene zone. Morphology and composition of micrometer-sized Au mineral spherules were studied with SEM and laser microprobe. The newly formed segregations of secondary gold on the surface of its residual grains were also an object of investigation. The character of such overgrowths is the most indicative for nanoparticles. The newly formed Au particles provide evidence for redistribution of ultradispersed gold during weathering. There are serious prerequisites to state that microorganisms substantially control unusual nano-sized microspherical morphology of gold particles in the supergene zone. This is supported by experiments indicating active absorption of gold by microorganisms and direct evidence for participation of Ralstonia metallidurans bacteria in the formation of peculiar corroded bacteriomorphic surface of gold grains. In addition, the areas enriched in carbon and nitrogen have been detected with SEM on the surface of gold spherules from Guinea. Such organic compounds as serine, alanine, and glycine are identified on their surface with Raman spectroscopy. The experiments have been carried out and new data have been obtained indicating the role of micromycetes in concentration and distribution of noble metals in ferromanganese nodules of the World Ocean. Au and Pt were detected in the system with radioisotopes. It has been established that two forms of gold distribution develop within pseudomorphs of fungi colonies: (1) as pseudomorphic concentrates and (2) dispersed form unrelated to the colony structure. Inhomogeneities in distribution of dispersed platinum are manifested in the form of linear anomalies with elevated concentrations at the margins of the colonies.

Zhmodik, S. M.; Kalinin, Yu. A.; Roslyakov, N. A.; Mironov, A. G.; Mikhlin, Yu. L.; Belyanin, D. K.; Nemirovskaya, N. A.; Spiridonov, A. M.; Nesterenko, G. V.; Airiyants, E. V.; Moroz, T. N.; Bul'bak, T. A.

2012-04-01

337

Reduction of chloroacetone over silica-supported noble metal catalysts  

Microsoft Academic Search

The reduction of chloroacetone over silica-supported noble metal catalysts yielded the hydrodechlorinated (acetone), the hydrogenated (1-chloro-2-propanol), and the hydrodechlorinated–hydrogenated (2-propanol) products at different selectivities depending on the catalyst used. Pd\\/SiO2 catalyzed the single-step hydrodechlorination preferentially to give acetone selectively. Pt\\/SiO2 promoted the hydrogenation into 1-chloro-2-propanol concurrently and the consecutive hydrogenation of acetone into 2-propanol as well. Over Rh\\/SiO2, acetone was

Tohru Mori; Daisuke Tomikawa; Yuji Katano; Jun Kubo; Yutaka Morikawa

2004-01-01

338

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

NASA Astrophysics Data System (ADS)

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.

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

339

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

Microsoft Academic Search

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

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

1984-01-01

340

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

Microsoft Academic Search

High-level radioactive sludge at the Savannah River Site (SRS) will be processed at the Defense Waste Processing Facility (DWPF) into durable borosilicate glass wasteforms. The sludges are analyzed for elemental content before processing to ensure compatibility with the glass-making processes. Noble metal fission products in sludge, can under certain conditions, cause problems in the glass melter. Therefore, reliable noble metal

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

1990-01-01

341

Hot Topics in Cold Gases  

E-print Network

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

Robert Seiringer

2009-08-25

342

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

DOEpatents

A heavy metal poisoned, spent FCC catalyst is treated by chemically impregnating the poisoned catalyst with a new catalytic metal or metal salt to provide an attrition resistant catalyst or sorbent for a different catalytic or absorption process, such as catalysts for Fischer-Tropsh Synthesis, and sorbents for removal of sulfur gases from fuel gases and flue-gases. The heavy metal contaminated FCC catalyst is directly used as a support for preparing catalysts having new catalytic properties and sorbents having new sorbent properties, without removing or passivating the heavy metals on the spent FCC catalyst as an intermediate step.

Gangwal, S.; Jothimurugesan, K.

1999-07-27

343

Isotopic and elemental fractionation of solar wind implanted in the Genesis concentrator target characterized and quantified by noble gases  

NASA Astrophysics Data System (ADS)

We report concentrations and isotopic compositions of He, Ne, and Ar measured with high spatial resolution along a radial traverse of a silicon carbide (SiC) quadrant of the Genesis mission concentrator target. The Ne isotopic composition maps instrumental fractionation as a function of radial position in the target: the maximum observed isotopic fractionation is approximately 33‰ per mass unit between the center and periphery. The Ne fluence is enhanced by a factor of 43 at the target center and decreases to 5.5 times at the periphery relative to the bulk solar wind fluence. Neon isotopic profiles measured along all four arms of the "gold cross" mount which held the quadrants in the concentrator target demonstrate that the concentrator target was symmetrically irradiated during operation as designed. We used implantation experiments of Ne into SiC and gold to quantify backscatter loss and isotopic fractionation and compared measurements with numerical simulations from the code "stopping and range of ions in matter." The 20Ne fluence curve as a function of radial distance on the target may be used to construct concentration factors relative to bulk solar wind for accurate corrections for solar wind fluences of other light elements to be measured in the concentrator target. The Ne isotopic composition as a function of the radial distance in the SiC quadrant provides a correction for the instrumental mass-dependent isotopic fractionation by the concentrator and can be used to correct measured solar wind oxygen and nitrogen isotopic compositions to obtain bulk solar wind isotopic compositions.

Heber, Veronika S.; Wiens, Roger C.; Jurewicz, Amy J. G.; Vogel, Nadia; Reisenfeld, Daniel B.; Baur, Heinrich; McKeegan, Kevin D.; Wieler, Rainer; Burnett, Donald S.

2011-04-01

344

Recombination-amplitude calculations of noble gases, in both length and acceleration forms, beyond the strong-field approximation  

E-print Network

Transition of an electron from a free to a bound state is critical in determining the qualitative shape of the spectrum in high-order-harmonic generation (HHG), and in tomographic imaging of orbitals. We calculate and ...

Bhardwaj, Siddharth

345

Adsorption and desorption of noble gases on activated charcoal: II. sup 222 Rn studies in a monolayer and packed bed  

SciTech Connect

The adsorptive and desorptive characteristics of canisters containing a petroleum-based charcoal were investigated under controlled conditions of temperature, relative humidity, and Rn concentration. Charcoals exposed in a monolayer and packed bed during exposure intervals of 1-7 d demonstrate that Rn adsorption and desorption are dependent on bed depth and the amount of water adsorbed. Changes in the adsorptive and desorptive properties of the charcoal occurred near the break-point where the pores became occluded by water vapor that condenses in the entrance capillaries. Radon-222 adsorption is decreased by an order of magnitude as the amount of adsorbed water exceeds the break-point of the charcoal. The reduction in pore surface due to adsorbed water results in a marked increase in the rate of Rn loss from exposed canisters, accounting for reduced adsorption. The apparent desorption time-constant for a 2-cm bed of loose Witco 6 x 10 mesh charcoal containing 0.220-0.365 kg H{sub 2}O kg-1 is typically between 2-8 h. The apparent desorption time-constant for an equivalent packed bed containing a water vapor content of 0.026-0.060 kg H{sub 2}O kg-1, which is below the break-point of the charcoal, is about 15-30 h. Conventional charcoal canisters, if exposed in the fully-opened configuration, can achieve the break-point in less than 4 d at 70% humidity. The use of a diffusion barrier would allow for longer exposure times until the break-point of the charcoal is achieved.

Scarpitta, S.C.; Harley, N.H. (Department of Energy, New York, NY (USA))

1990-10-01

346

Ignition dynamics of dry-etched vertical cavity single-hole microdischarge reactors in ac regime operating in noble gases  

NASA Astrophysics Data System (ADS)

Silicon-based multi-cavity microdischarge reactors allow the generation of large-area uniform glow discharges over a wide pressure range up to atmospheric pressure. These devices, fabricated using micro electro-mechanical system technology, have shown complex interactions between the individual cavities. To discriminate these interactions, devices with only one shallow vertical cavity are studied here. Operation characteristics are investigated using electrical and optical analysing techniques. The spatial and temporal dynamics of the discharge are investigated for positive and negative voltage polarity of the applied ac voltage ramp by phase-resolved imaging. Within each voltage half-period, emission from the single cavity shows repetitive pulsing features and distinct spatial distributions. In the positive half-period, ring-shaped structures develop, while the negative half-period is distinguished by a bell-shaped intensity distribution. Effects of pressure and operation frequency on the spatial and temporal intensity profiles are discussed.

Kulsreshath, M. K.; Golda, J.; Felix, V.; Schulz-von der Gathen, V.; Dussart, R.

2014-08-01

347

Plasmon resonances in linear noble-metal chains  

NASA Astrophysics Data System (ADS)

The electronic excitations of three noble-metall chains—copper, silver, and gold—have been investigated at the time-dependent density functional theory level. The reduced single-electron density matrix is propagated according to the Liouville-von Neumann equation in the real-time domain after an impulse excitation. The propagation in the real-time domain enables us to investigate the formation and size evolution of electronic excitations in these metallic chains with different number of atoms, up to a total of 26 atoms. The longitudinal oscillations at lower excitation energies are dominated by s ? p transitions in these chains and have collective or central resonances, while the first peak involving d ? p transitions in the longitudinal mode appears at a higher excitation energy and shows collective resonances. In the transverse oscillations, there are in most cases d ? p transitions in each resonance, which can be attributed to either central or end resonances. Convergence of the oscillations, in particular those involving the collective and central resonances in the three noble-metal chains can only be observed for chains with 18 atoms or more. Different spectroscopic characteristics among these three metallic chains can be attributed to their different electronic structures, in particular the relativistic effects in the gold chains have a dramatic effect on their electronic structures and excitations.

Gao, Bin; Ruud, Kenneth; Luo, Yi

2012-11-01

348

Quantum Gases in Optical Lattices  

NASA Astrophysics Data System (ADS)

The experimental realization of correlated quantum phases with ultracold gases in optical lattices and their theoretical understanding has witnessed remarkable progress during the last decade. In this review we introduce basic concepts and tools to describe the many-body physics of quantum gases in optical lattices. This includes the derivation of effective lattice Hamiltonians from first principles and an overview of the emerging quantum phases. Additionally, state-of-the-art numerical tools to quantitatively treat bosons or fermions on different lattices are introduced.

Barmettler, Peter; Kollath, Corinna

2015-09-01

349

Method for detecting toxic gases  

DOEpatents

A method is disclosed which is capable of detecting low concentrations of a pollutant or other component in air or other gas. This method utilizes a combination of a heating filament having a catalytic surface of a noble metal for exposure to the gas and producing a derivative chemical product from the component. An electrochemical sensor responds to the derivative chemical product for providing a signal indicative of the product. At concentrations in the order of about 1-100 ppm of tetrachloroethylene, neither the heating filament nor the electrochemical sensor is individually capable of sensing the pollutant. In the combination, the heating filament converts the benzyl chloride to one or more derivative chemical products which may be detected by the electrochemical sensor. 6 figures.

Stetter, J.R.; Zaromb, S.; Findlay, M.W. Jr.

1991-10-08

350

Using noble gas tracers to estimate residual CO2 saturation in the field: results from the CO2CRC Otway residual saturation and dissolution test  

NASA Astrophysics Data System (ADS)

Residual CO2 saturation is a critically important parameter in CO2 storage as it can have a large impact on the available secure storage volume and post-injection CO2 migration. A suite of single-well tests to measure residual trapping was conducted at the Otway test site in Victoria, Australia during 2011. One or more of these tests could be conducted at a prospective CO2 storage site before large-scale injection. The test involved injection of 150 tonnes of pure carbon dioxide followed by 454 tonnes of CO2-saturated formation water to drive the carbon dioxide to residual saturation. This work presents a brief overview of the full test sequence, followed by the analysis and interpretation of the tests using noble gas tracers. Prior to CO2 injection krypton (Kr) and xenon (Xe) tracers were injected and back-produced to characterise the aquifer under single-phase conditions. After CO2 had been driven to residual the two tracers were injected and produced again. The noble gases act as non-partitioning aqueous-phase tracers in the undisturbed aquifer and as partitioning tracers in the presence of residual CO2. To estimate residual saturation from the tracer test data a one-dimensional radial model of the near-well region is used. In the model there are only two independent parameters: the apparent dispersivity of each tracer and the residual CO2 saturation. Independent analysis of the Kr and Xe tracer production curves gives the same estimate of residual saturation to within the accuracy of the method. Furthermore the residual from the noble gas tracer tests is consistent with other measurements in the sequence of tests.

LaForce, T.; Ennis-King, J.; Paterson, L.

2013-12-01

351

Feshbach Resonances in Ultracold Gases  

NASA Astrophysics Data System (ADS)

In this chapter, we describe scattering resonance phenomena in general, and focus on the mechanism of Feshbach resonances, for which a multi-channel treatment is required. We derive the dependence of the scattering phase shift on magnetic field and collision energy. From this, the scattering length and effective range coefficient can be extracted -- expressions which are particularly useful for ultracold gases.

Kokkelmans, Servaas

2015-09-01

352

Interaction quenches of Fermi gases  

SciTech Connect

It is shown that the jump in the momentum distribution of Fermi gases evolves smoothly for small and intermediate times once an interaction between the fermions is suddenly switched on. The jump does not vanish abruptly. The loci in momentum space where the jumps occur are those of the noninteracting Fermi sea. No relaxation of the Fermi surface geometry takes place.

Uhrig, Goetz S. [Lehrstuhl fuer Theoretische Physik I, Technische Universitaet Dortmund, Otto-Hahn Strasse 4, D-44221 Dortmund (Germany)

2009-12-15

353

Greenhouse gases thinning the thermosphere  

NSDL National Science Digital Library

Orbital decay rates of satellites and other objects that have flown continually for more than 30 years were analyzed to determine the concentrations of greenhouse gases in the thermosphere. A decrease of 25 percent per decade was found in the thermosphere's density since 1966. Implications are discussed.

Emmert et al.

354

GREENHOUSE GASES AND GLOBAL WARMING  

Microsoft Academic Search

Summary Global warming is an important environmental issue which is rapidly becoming a part of popular culture. This paper provides an account of the science associated with this important issue. Historical evidence for past climate change is discussed. The difference between weather and climate is highlighted. The physics of the greenhouse effect and the concept of greenhouse gases are presented.

Timothy J. Wallington; Jayaraman Srinivasan; Ole John Nielsen; Ellie J. Highwood

355

40 CFR 86.1514 - Analytical gases.  

Code of Federal Regulations, 2010 CFR

... false Analytical gases. 86.1514 Section...CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL...Methanol-Fueled Natural Gas-Fueled, and Liquefied Petroleum Gas-Fueled Diesel-Cycle...1514 Analytical gases. (a) The...

2010-07-01

356

DEVELOPMENT OF A NON-NOBLE METAL HYDROGEN PURIFICATION SYSTEM  

SciTech Connect

Development of advanced hydrogen separation membranes in support of hydrogen production processes such as coal gasification and as front end gas purifiers for fuel cell based system is paramount to the successful implementation of a national hydrogen economy. Current generation metallic hydrogen separation membranes are based on Pd-alloys. Although the technology has proven successful, at issue is the high cost of palladium. Evaluation of non-noble metal based dense metallic separation membranes is currently receiving national and international attention. The focus of the reported work was to develop a scaled reactor with a VNi-Ti alloy membrane to replace a production Pd-alloy tube-type purification/diffuser system.

Korinko, P; Kyle Brinkman, K; Thad Adams, T; George Rawls, G

2008-11-25

357

Optical spectra of noble metal nanoparticles supported on zeolites  

NASA Astrophysics Data System (ADS)

Optical spectra of noble metal nano-particles supported on different types of zeolites are studied and compared. The absorbance spectra of Cu, Ag and Au nanoparticles supported on mordenite, ?-zeolite, Na/Y and H/Y zeolites respectively are reported. Spectra for pre-exchanged Au-Cu/Na/Y, Au-Ni/Na/Y and Au-Fe/Na/Y are also studied. A simple effective medium approach (Maxwell-Garnett) is used to obtain a theoretical complex effective dielectric function of the composite and to asses the sensibility of the plasmon resonance to the sample characteristics. The knowledge of these properties can hopefully be applied to the development of optical tools to monitor the synthetic path.

López Bastidas, Catalina; Smolentseva, Elena; Machorro, Roberto; Petranovskii, Vitalii

2014-09-01

358

Predicted Organic Noble-Gas Hydrides Derived from Acrylic Acid.  

PubMed

The Ar-, Kr-, and Xe-insertion compounds into acrylic acid, i.e., C2H3COONgH (Ng = Ar, Kr, and Xe), have been studied by ab initio calculations. The geometry optimization, frequency calculation, and stability were investigated at the MP2/aug-cc-pVTZ (aug-cc-pVTZ-PP) level of theory. Two configuration isomers, i.e., s-cis syn (isomer A) and s-cis anti (isomer B), were optimized for each molecule. Using the s-cis syn structure (isomer A) as an example, we performed natural bond orbital (NBO) analysis, natural energy decomposition analysis (NEDA), and atom-in-molecules (AIM) analysis to investigate the bonding nature of these noble-gas compounds. Our study predicts the existence of Kr- and Xe-derivatives of acrylic acid and the instability of Ar-related compounds. PMID:25340827

Zhang, Min; Gao, Kunqi; Sheng, Li

2014-11-01

359

DARWIN: dark matter WIMP search with noble liquids  

E-print Network

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

Laura Baudis; for the DARWIN Consortium

2012-01-11

360

DARWIN: dark matter WIMP search with noble liquids  

E-print Network

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

Laura Baudis

2010-12-21

361

DARWIN: dark matter WIMP search with noble liquids  

E-print Network

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

Baudis, Laura

2012-01-01

362

C5Li7(+) and O2Li5(+) as noble-gas-trapping agents.  

PubMed

The noble-gas-trapping ability of the star-shaped C(5)Li(7)(+) cluster and O(2)Li(5)(+) super-alkali cluster is studied by using ab initio and density functional theory (DFT) at the MP2 and M05-2X levels with 6-311+G(d,p) and 6-311+G(d) basis sets. These clusters are shown to be effective noble-gas-trapping agents. The stability of noble-gas-loaded clusters is analyzed in terms of dissociation energies, reaction enthalpies, and conceptual DFT-based reactivity descriptors. The presence of an external electric field improves the dissociation energy. PMID:23296901

Pan, Sudip; Contreras, Maryel; Romero, Jonathan; Reyes, Andres; Chattaraj, Pratim K; Merino, Gabriel

2013-02-11

363

Energy gases - the methane age and beyond  

Microsoft Academic Search

The combustion of fossil fuels results in the emissions of gases and pollutants that produce adverse ecological effects. Evidence is also accumulating that suggests they may also cause global climate change. The combustion gases that are connected with global climate change are primarily carbon dioxide (CO[sub 2]) and to a lesser degree methane (CH[sub 4]). All of these gases already

Nakicenovic

1993-01-01

364

Heavy periodane.  

PubMed

The potential energy surface of the hypothetical NaMgAlSiPSCl system (heavy periodane) is exhaustively analyzed via the gradient embedded genetic algorithm (GEGA) in combination with density functional theory (DFT) computations. The electronegativity differences among the elements in both the second and third rows of the periodic table indicate that low-energy heavy periodane structures are obtained when highly electronegative and electropositive elements are bound together, but the global minimum of the heavy periodane system is completely different to its second-row analog (LiBeBCNOF). PMID:22903586

Azpiroz, Jon M; Moreno, Diego; Ramirez-Manzanares, Alonso; Ugalde, Jesus M; Mendez-Rojas, Miguel Angel; Merino, Gabriel

2013-05-01

365

Hot and Cold Ideal Gases  

NSDL National Science Digital Library

The EJS Hot and Cold Ideal Gases model simulates the mixing of hot and cold two-dimensional ideal gases in a square box. This simulation can be used as part of the activity described in "The Statistical Interpretation of Entropy: An Activity" by Todd Timberlake, to be published in The Physics Teacher. In the model, one gas is initially confined to the left side of the box while the other gas is confined to the right side. An animation window shows the motion of the particles in the box, while an optional graph window plots the temperature of each side of the box, which is determined by measuring the average KE of the particles on each side. The initial number of particles and temperature on each side of the square can be changed and a button allows the user to reverse the particle velocities at any time. The user can modify this simulation if EJS is installed locally by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item. EJS Hot and Cold Ideal Gases model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_entropy_HotAndColdIdealGases.jar file will run the program if Java is installed. EJS is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional EJS models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or EJS.

Timberlake, Todd

2010-07-01

366

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

PubMed

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

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

2002-03-22

367

Immobilizing highly catalytically active noble metal nanoparticles on reduced graphene oxide: a non-noble metal sacrificial approach.  

PubMed

In this work, we have developed a non-noble metal sacrificial approach for the first time to successfully immobilize highly dispersed AgPd nanoparticles on reduced graphene oxide (RGO). The Co3(BO3)2 co-precipitated with AgPd nanoparticles and subsequently sacrificed by acid etching effectively prevents the primary AgPd particles from aggregation. The resulted ultrafine AgPd nanoparticles exhibit the highest activity (turnover frequency, 2739 h(-1) at 323 K) among all the heterogeneous catalysts for the dehydrogenation of formic acid to generate hydrogen without CO impurity. The sacrificial approach opens up a new avenue for the development of high-performance metal nanocatalysts. PMID:25543717

Chen, Yao; Zhu, Qi-Long; Tsumori, Nobuko; Xu, Qiang

2015-01-14

368

Heavy Flavors  

NASA Astrophysics Data System (ADS)

This is a summary report of the working group on Heavy Flavors. Discussions at the workshop were centered on B physics and on the signals for heavy quarks and leptons at the SSC. The Working Group Members were: V. Barger, H.-U. Bengtsson, C. Buchanan, I. Bigi, M. Block, B. Cox, N. Glover, J. Hewett, W.Y. Keung, B. Margolis, T. Rizzo, M. Suzuki, A. Soni, D. Stork, and S. Willenbrock.

Cox, B.; Soni, A.

369

Synergistic effect of Brønsted acid and platinum on purification of automobile exhaust gases  

PubMed Central

The catalytic purification of automobile exhaust gases (CO, NOx and hydrocarbons) is one of the most practiced conversion processes used to lower the emissions and to reduce the air pollution. Nevertheless, the good performance of exhaust gas purification catalysts often requires the high consumption of noble metals such as platinum. Here we report that the Brønsted acid sites on the external surface of a microporous silicoaluminophosphate (SAPO) act as a promoter for exhaust gas purification, effectively cutting the loading amount of platinum in the catalyst without sacrifice of performance. It is revealed that in the Pt-loaded SAPO-CHA catalyst, there exists a remarkable synergistic effect between the Brønsted acid sites and the Pt nanoparticles, the former helping to adsorb and activate the hydrocarbon molecules for NO reduction during the catalytic process. The thermal stability of SAPO-CHA also makes the composite catalyst stable and reusable without activity decay. PMID:23907148

Fu, Wei; Li, Xin-Hao; Bao, Hong-Liang; Wang, Kai-Xue; Wei, Xiao; Cai, Yi-Yu; Chen, Jie-Sheng

2013-01-01

370

Noble gas behavior during deformation and serpentinization of abyssal peridotites: St. Peter-St. Paul massif  

NASA Astrophysics Data System (ADS)

We present new noble gas (He, Ne, Ar), Sr and Pb isotopic analyses of St. Peter-St. Paul (SPSP) abyssal peridotites sampled in 1998-1999 using the Nautile submersible (IFREMER). The goals of the study were to geochemically characterize both granular and mylonitized peridotites, and to evaluate the effects of mylonitization and serpentinization on rare gas concentrations and isotopic compositions. Samples included whole rocks for mylonitic peridotites, and mineral separates (serpentine and olivine+pyroxene) from massive peridotites. The abyssal peridotites exhibit strong enrichment in light rare earths and other incompatible elements, and positive Ce anomalies are found in several non-mylonitic samples. Mylonitic samples are characterized by lower loss on ignition, and higher SiO2 and MgO, and unradiogenic 87Sr/86Sr isotopic composition (~0.7034) and extremely radiogenic 206Pb/204Pb (up to 20), which is more radiogenic than previous measurements from SPSP. Rare gas analyses were made by paired in vacuo crushing and melting of whole rocks and mineral separates. Most SPSP peridotites contain high concentrations of He, Ne, and Ar that are air-like demonstrating atmospheric contamination. The group of samples plots along a He-Ne mixing line between air and typical mantle values, where the mylonitic samples are characterized by higher fractions of mantle Ne (20Ne/22Ne>10) and 3He/4He (R/Ra~7). The binary mixing behavior is also supported by Ar-Ne isotopes. For the mylonites, melting released high concentrations of He (1.4x10-5ccSTP/g) and the most radiogenic argon (40Ar/36Ar = 2810), demonstrating that noble gases are stored in the crystal structure of the minerals. In contrast, the undeformed peridotites had much lower total helium concentrations for both serpentine (2x10-8ccSTP/g) and olivine+pyroxene (6.9x10-8ccSTP/g) separates. The serpentine mineral separate showed low 3He/4He (R/Ra~1) that was similar in both crushed and melting methods and low air-like 40Ar/36Ar (~355), although they released the highest argon concentration (3.2x10-5cc/g). The low He concentrations suggest that serpentine is not a determining mineral phase in He fractionation. The olivine+pyroxene mineral separates yield lower 3He/4He through the melting method and similar to whole rock values and lower 40Ar/36Ar (~383). Because melt inclusions are not found in the mylonites, the large fraction of 4He released during melting suggests that a significant mantle component may be retained in the recrystallized neoblasts during the deformation processes. It is hypothesized that recrystallization and grain growth in the mylonitization process may have favored gas retention (i.e. supporting a relationship between deformation and gas contents), or is related to metasomatism in a gas-rich (CO2 and rare gas) environment.

Angel Amaya, J.; Kurz, M. D.; Sichel, S. E.; Blusztajn, J.

2010-12-01

371

Release of gases from uranium metal at high temperatures  

NASA Astrophysics Data System (ADS)

Depending on the ambient environmental conditions, different gaseous species could get entrapped in uranium metal ingots or pellets. On heating, melting or vapourising uranium metal, these get released and depending on the composition, may cause detrimental effects either within the metal matrix itself or on the surrounding materials/environment. For instance, these gases may affect the performance of the uranium metal, which is used as fuel in the heavy water moderated research reactors, CIRUS and DHRUVA. Hence, detailed investigations have been carried out on the release of gases over a temperature range 875-1500 K employing hot vacuum extraction technique, in specimen uranium pellets made from uranium rods/ingots. Employing an on-line quadrupole mass spectrometer, the analysis of released gases was carried out. The isobaric interference between carbon monoxide and nitrogen at m/ e = 28 in the mass spectrometric analysis has been resolved by considering their fragmentation patterns. Since no standards are available to evaluate the results, only the reproducibility is tested. The precision (relative standard deviation at 3 ? level) of the method is ±5%. The minimum detectable gas content employing the method is 5.00 × 10 -09 m 3. About 4 × 10 -04 m 3/kg of gas is released from uranium pellets, with hydrogen as the main constituent. The gas content increases with storage in air.

Sayi, Y. S.; Ramanjaneyulu, P. S.; Yadav, C. S.; Shankaran, P. S.; Chhapru, G. C.; Ramakumar, K. L.; Venugopal, V.

2008-02-01

372

Molecular and isotopic compositions and origin of natural gases from Cambrian and Carboniferous-Lower Permian reservoirs of the onshore Polish Baltic region  

NASA Astrophysics Data System (ADS)

Natural gases from Middle Cambrian and Carboniferous-Lower Permian reservoirs of the onshore Polish Baltic region were studied for their molecular and stable isotope compositions. The following gas species were analysed: 12,13C in CH4, C2H6, C3H8, n-C4H10, i-C4H10 and CO2, 1,2H in CH4, 14,15N in N2, and stable isotopes of all noble gases. Due to significantly different geological settings and genetic types of source rocks of Eastern and Western Pomerania, the molecular and isotopic compositions of natural gases of these two regions exhibit distinct differences. Hydrocarbon gases associated with oil accumulated in the Middle Cambrian reservoir of Eastern Pomerania were generated during low-temperature thermogenic processes from a single source rock containing Type-II kerogen at one phase of petroleum generation. Non-associated hydrocarbon gases accumulated in the Carboniferous (Mississippian and Pennsylvanian)-Lower Permian (Rotliegend) reservoirs of Western Pomerania originated during at least two phases of gas generation by thermogenic processes from mainly Type-III kerogen and a small component of mixed Type-III/II kerogen. Noble gases are in general heavily enriched in radiogenic and nucleogenic isotopes such as 4He, 40Ar and 21Ne accumulated in the reservoirs. Weak contributions of mantle-derived He and Ne are observed. Radiogenic 4He/40Ar ratios are higher than the average production rate ratio of about 5 for radiogenic 4He/40Ar in crustal materials, which might have been caused by a selective supply of 4He that is lighter than 40Ar from crustal rocks, or (U + Th)/K ratio might be higher than the average in crustal block. Carbon dioxide from gases of both the Western and Eastern Pomerania were mainly generated during thermogenic processes of transformation of organic matter, although gases of Western Pomerania can contain an endogenic component. Molecular nitrogen from the Eastern Pomeranian natural gases was mainly generated during low-temperature thermal transformation of organic matter and derived from NH3 and NH4 of crustal fluid, whereas molecular nitrogen from Western Pomeranian natural gases contains a significant component from the destruction of organic matter at a higher maturity level which may have been caused by a high heat flux from the volcanic activity during late Pennsylvanian-early Rotliegend ages, and has a bigger component release from NH4-rich illites.

Kotarba, Maciej J.; Nagao, Keisuke

2014-08-01

373

Molecular and isotopic compositions and origin of natural gases from Cambrian and Carboniferous-Lower Permian reservoirs of the onshore Polish Baltic region  

NASA Astrophysics Data System (ADS)

Natural gases from Middle Cambrian and Carboniferous-Lower Permian reservoirs of the onshore Polish Baltic region were studied for their molecular and stable isotope compositions. The following gas species were analysed: 12,13C in CH4, C2H6, C3H8, n-C4H10, i-C4H10 and CO2, 1,2H in CH4, 14,15N in N2, and stable isotopes of all noble gases. Due to significantly different geological settings and genetic types of source rocks of Eastern and Western Pomerania, the molecular and isotopic compositions of natural gases of these two regions exhibit distinct differences. Hydrocarbon gases associated with oil accumulated in the Middle Cambrian reservoir of Eastern Pomerania were generated during low-temperature thermogenic processes from a single source rock containing Type-II kerogen at one phase of petroleum generation. Non-associated hydrocarbon gases accumulated in the Carboniferous (Mississippian and Pennsylvanian)-Lower Permian (Rotliegend) reservoirs of Western Pomerania originated during at least two phases of gas generation by thermogenic processes from mainly Type-III kerogen and a small component of mixed Type-III/II kerogen. Noble gases are in general heavily enriched in radiogenic and nucleogenic isotopes such as 4He, 40Ar and 21Ne accumulated in the reservoirs. Weak contributions of mantle-derived He and Ne are observed. Radiogenic 4He/40Ar ratios are higher than the average production rate ratio of about 5 for radiogenic 4He/40Ar in crustal materials, which might have been caused by a selective supply of 4He that is lighter than 40Ar from crustal rocks, or (U + Th)/K ratio might be higher than the average in crustal block. Carbon dioxide from gases of both the Western and Eastern Pomerania were mainly generated during thermogenic processes of transformation of organic matter, although gases of Western Pomerania can contain an endogenic component. Molecular nitrogen from the Eastern Pomeranian natural gases was mainly generated during low-temperature thermal transformation of organic matter and derived from NH3 and NH4 of crustal fluid, whereas molecular nitrogen from Western Pomeranian natural gases contains a significant component from the destruction of organic matter at a higher maturity level which may have been caused by a high heat flux from the volcanic activity during late Pennsylvanian-early Rotliegend ages, and has a bigger component release from NH4-rich illites.

Kotarba, Maciej J.; Nagao, Keisuke

2015-01-01

374

From (b)edouin to (a)borigine: the myth of the desert noble savage.  

PubMed

This article examines the myth of the supposed superiority of the desert noble savage over civilized man. With the Bedouin of Arabia and the Aborigines of Australia as its two prime examples, the article argues that two versions of this myth can be traced: one in which the desert noble savage is valorized due to his valour, physical prowess and martial skill (Bedouin); and another, later version, where the desert noble savage is valorized as a pacifist, an ecologist and a mythmaker/storyteller (Aborigines). The article concludes by examining the way in which this turn from one type of desert noble savage to another reflects the manner in which western modernity has shifted its values from Cartesian dualities and Enlightenment rationalism to that of networks, potentialities, ecology and myth. PMID:19886291

Graulund, Rune

2009-01-01

375

9th Annual Oklahoma Native American Youth Language Fair Sam Noble Oklahoma Museum of Natural History  

E-print Network

9th Annual Oklahoma Native American Youth Language Fair Sam Noble Oklahoma Museum of Natural History University of Oklahoma Elder Voices, Youth Choices from the Oklahoma Native American Youth Language Fair! We are pleased

Oklahoma, University of

376

CO oxidation studies over supported noble metal catalysts and single crystals: A review  

NASA Technical Reports Server (NTRS)

The catalytic oxidation of CO over noble metal catalysts is reviewed. Results obtained on supported noble metal catalysts and single crystals both at high pressures and under UHV conditions are compared. The underlying causes which result in surface instabilities and multiple steady-state oscillations are considered, in particular, the occurrence of hot spots. CO islands of reactivity, surface oxide formation and phase transformations under oscillatory conditions are discussed.

Boecker, Dirk; Gonzalez, Richard D.

1987-01-01

377

Preparation and performance of noble metal phosphides supported on silica as new hydrodesulfurization catalysts  

Microsoft Academic Search

Preparation of noble metal (NM) (Rh, Pd, Ru, Pt) phosphide species and their catalytic activities for hydrodesulfurization (HDS) of thiophene were investigated. Noble metal phosphides (NMXPY) catalysts were prepared by reduction of P-added NM (NM-P) supported on silica (SiO2) with hydrogen. Hydrogen consumption peaks at around 350–700°C, which were attributed to the formation of NMXPY, were observed in temperature-programmed reduction

Yasuharu Kanda; Chisato Temma; Keisuke Nakata; Takao Kobayashi; Masatoshi Sugioka; Yoshio Uemichi

2010-01-01

378

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

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

379

Direct detection of dark matter with noble liquid detectors  

NASA Astrophysics Data System (ADS)

The search for non-baryonic, non-luminous dark matter that comprises approximately 23% of our universe is an exciting endeavor. However, detecting this matter has proved difficult as it does not interact through the electromagnetic force but only by scattering elastically off of target nuclei on the weak scale; therefore evidence of dark matter must be demonstrated through the observation of nuclear recoils induced by dark matter candidates. Because nuclear recoils can be caused by any type of elastic scattering reactions induced by radiogenic and cosmogenic processes, a dark matter detector must have an extremely low background. Moreover, the low energy signal of a dark matter event requires building detectors with large volumes of target material with low background. Noble liquids provide a promising target for the detection of dark matter. Of the noble elements, argon and xenon have been shown to be ideal targets in dark matter searches as they have excellent scintillation yield and are relatively inexpensive and scalable. However, natural argon contains a radioactive isotope, 39Ar, that must be reduced in order to observe a rare dark matter event. Several technologies exist that can be utilized to reduce the concentration of this element including thermal diffusion, underground water sources and laser isotope separation. Thermal diffusion employs a temperature gradient in order to separate gaseous argon isotopes along the length of a cylindrical column. A test bench thermal diffusion column has been constructed which resulted in the significant depletion of 36Ar in a natural argon sample. Underground water sources have also been evaluated in the pursuit of natural argon depleted of the 39Ar isotope. Since the water in these sources has not been in contact with atmospheric air for several thousand years that 39Ar should have decayed away. A water source at Wall, SD has been obtained and evaluated for depleted argon using a water degassing apparatus and a proportional counter. The water sample obtained from this source showed a reduction of 39Ar by a factor of three.

Spaans, Jason

380

Noble metal aerogels-synthesis, characterization, and application as electrocatalysts.  

PubMed

Conspectus Metallic and catalytically active materials with high surface area and large porosity are a long-desired goal in both industry and academia. In this Account, we summarize the strategies for making a variety of self-supported noble metal aerogels consisting of extended metal backbone nanonetworks. We discuss their outstanding physical and chemical properties, including their three-dimensional network structure, the simple control over their composition, their large specific surface area, and their hierarchical porosity. Additionally, we show some initial results on their excellent performance as electrocatalysts combining both high catalytic activity and high durability for fuel cell reactions such as ethanol oxidation and the oxygen reduction reaction (ORR). Finally, we give some hints on the future challenges in the research area of metal aerogels. We believe that metal aerogels are a new, promising class of electrocatalysts for polymer electrolyte fuel cells (PEFCs) and will also open great opportunities for other electrochemical energy systems, catalysis, and sensors. The commercialization of PEFCs encounters three critical obstacles, viz., high cost, insufficient activity, and inadequate long-term durability. Besides others, the sluggish kinetics of the ORR and alcohol oxidation and insufficient catalyst stability are important reasons for these obstacles. Various approaches have been taken to overcome these obstacles, e.g., by controlling the catalyst particle size in an optimized range, forming multimetallic catalysts, controlling the surface compositions, shaping the catalysts into nanocrystals, and designing supportless catalysts with extended surfaces such as nanostructured thin films, nanotubes, and porous nanostructures. These efforts have produced plenty of excellent electrocatalysts, but the development of multisynergetic functional catalysts exhibiting low cost, high activity, and high durability still faces great challenges. In this Account, we demonstrate that the sol-gel process represents a powerful "bottom-up" strategy for creating nanostructured materials that tackles the problems mentioned above. Aerogels are unique solid materials with ultralow densities, large open pores, and ultimately high inner surface areas. They magnify the specific properties of nanomaterials to the macroscale via self-assembly, which endow them with superior properties. Despite numerous investigations of metal oxide aerogels, the investigation of metal aerogels is in the early stage. Recently, aerogels including Fe, Co, Ni, Sn, and Cu have been obtained by nanosmelting of hybrid polymer-metal oxide aerogels. We report here exclusively on mono-, bi- and multimetallic noble metal aerogels consisting of Ag, Au, Pt, and Pd and their application as electrocatalysts. PMID:25611348

Liu, Wei; Herrmann, Anne-Kristin; Bigall, Nadja C; Rodriguez, Paramaconi; Wen, Dan; Oezaslan, Mehtap; Schmidt, Thomas J; Gaponik, Nikolai; Eychmüller, Alexander

2015-02-17

381

The Interaction of Hydrogen with Simple and Noble Metals Surfaces  

NASA Astrophysics Data System (ADS)

The basic concepts of adsorption are illustrated by the investigation of a simple adsorbate (hydrogen) with the "simplest" metals (simple and noble metals). Theoretically tractable, these systems serve as an excellent test of our basic understanding of chemisorption. The interaction of atomic and molecular hydrogen with the surfaces of Mg(0001), Mg(1120), Li(110), K(110), Ag(110), and Ag(111) have been studied with a variety of experimental probes. In all cases, no evidence for H_2 associative or dissociative adsorption is observed at the substrate temperature investigated (>=q90 K). In the case of the simple metals below 150 K, atomic hydrogen is bound to the surfaces in a strongly chemisorbed state (hydride). For Mg and Li, the hydride is localized to the surface wherein the substrate electron density is lower than the bulk. Because of the low electron density, hydrogen is absorbed into the bulk of K at low temperatures and forms a bulk-hydride phase. However, these low-temperature phases are metastable. In the case of Mg, hydrogen moves into lower energy configuration bonding sites which are closer to or below the surface plane. However, the hydride characteristics are absent; the H atom is effectively screened because of the higher jellium density. In contrast, upon annealing, hydrogen is absorbed into the bulk of Li and K and phase separation occurs forming regions of clean metal and bulk hydride areas. The results are compared to theoretical studies; the propensity for absorption over adsorption is understood in terms of jellium-based models. In the case of silver, at 100 K, atomic hydrogen bonds in trigonal sites on both the (110) and (111) surfaces. As a function of H concentration, a sequence of lattice gas superstructures is observed; these phases are accompanied by small H-induced displacements of the substrate surface atoms. In the case of Ag(110), the low-temperature phase is metastable; upon annealing, hydrogen desorption from low energy states is accompanied by a surface reconstruction. Although silver is a noble metal, many of the H-induced properties are characteristic of similar H/transition systems.

Sprunger, Phillip T.

382

The lifecycle of interstellar dust as constrained by noble gas implantation into SiC grains  

NASA Astrophysics Data System (ADS)

Primitive meteorites contain presolar grains that originated in stellar outflows and supernovae ejecta prior to the formation of the solar system. These grains represent a unique means to access interstellar matter within the framework of dust evolution. Laboratory measurements of the noble gas abundances trapped into a large sample of presolar SiC grains recovered from the Murchison meteorite showed a strong enrichment of the heavier gases (Xe, Kr) compared to the lighter ones (He, Ne, Ar) for both solar (so-called N) and Asymptotic Giant Branch (AGB)-star (so-called G) isotopic components isolated from SiC. This cannot possibly be due to nuclear processes, but requires some fractionation process. We have developed a simple atom implantation and grain erosion model which allows us to better understand this mass-fractionation of the elemental abundances and which provides new insights on both the physical conditions of grain formation and implantation around evolved stars and the processing of dust in circumstellar and interstellar environments. We argue in favor of an implantation at constant gas-grain velocity so that heavier elements are implanted more deeply, and thus are more susceptible to be conserved during erosion in the interstellar medium (ISM). We show that the N-component has been implanted in supernova-generated shock waves in the ISM, at a relatively low velocity (120 ± 40 km s-1) and high equivalent hydrogen-fluences (1018 to 1019 cm-2) in a so-called steady-state regime where implantation is accompanied by erosion. On the other hand, the G-component is consistent with implantation in the fast (220 ± 20 km s-1) wind of the planetary nebulae (PN) phase, at low H-fluences (1017 to 1018 cm-2) so that one can ignore erosion at this stage. In both cases, the mass-driven fractionation of the observed elemental abundances is a result of implantation in different astrophysical sites and subsequent erosion mainly in the ISM.

Guillard, P.; Jones, A. P.; Tielens, A. G. G. M.

2007-07-01

383

Climate Change and Greenhouse Gases  

NASA Technical Reports Server (NTRS)

The American Geophysical Union (AGU), as a scientific organization devoted to research on the Earth and space sciences, provides current scientific information to the public on issues pertinent to geophysics. The Council of the AGU approved a position statement on Climate Change and Greenhouse Gases in December 1998. The statement, together with a short summary of the procedures that were followed in its preparation, review, and adoption were published in the February 2, 1999 issue of Eos ([AGU, 1999]. The present article reviews scientific understanding of this issue as presented in peer-reviewed publications that serves as the underlying basis of the position statement.

Ledley, Tamara S.; Sundquist, Eric; Schwartz, Stephen; Hall, Dorothy K.; Fellows, Jack; Killeen, Timothy

1999-01-01

384

The intrusion of new magma triggered the 2011-2012 unrest at Santorini: evidence from noble-gas isotopes  

NASA Astrophysics Data System (ADS)

Santorini is one of the most famous active volcanoes of the world for its catastrophic explosive eruption that occurred during the Minoan civilization. Since then the Kameni eruptive centers that formed within the caldera erupted repeatedly until 1950. In 2011-2012 the volcano has been characterized by a seismic unrest, that was unprecedented at Santorini at least since the 1950 eruption, and that led to fear for an imminent eruption. Because more than 100,000 visitors are present on the island during the tourist season, and considering the eruptive potential of Santorini, it is crucial to evaluate the hazard of this volcano, which depends on the type of magma actually present in the volcanic system. With the aim to address this question, this research shows the first comparison between noble-gas isotope composition of the present fumarolic gases with that of fluid inclusions hosted in enclaves contained in the 1570 and 1925 AD dacitic magmas erupted at Nea Kameni. These enclaves are a portion of mafic magma batches that replenished the shallow chamber of the plumbing system hosting cooler and more silicic melts. Their Sr-Nd isotope ratios are quite similar to those measured in the host dacitic rocks, implying a common parental magma. Therefore, the analyzed enclaves may be considered representative of the historic magma erupted at Nea Kameni which could be still present in the volcano plumbing system feeding the crater fumaroles. The 3He/4He ratios of enclaves, once corrected for air contamination (3.1-3.6 Ra), partially overlap those of the gases (3.5-4.0 Ra) collected from Nea and Palea Kameni. The range of 3He/4He ratios (3.1-4.0 Ra) is appreciably lower than typical arc volcanoes (R/Ra ~7-8), implying that a contamination by 4He-rich fluids occurred either directly in the mantle and/or in the plumbing system. Comparison of 3He/4He and 4He/40Ar* ratios measured in enclaves with those of gases, as well as long-term monitoring of R/Ra in the latters, coherently indicate that the unrest in 2011-2012 was due to the injection into the plumbing system of a new batch of magma that is probably more mafic and less degassed than the basaltic-andesitic to dacitic magmas historically residing therein. All of the anomalies ceased in February 2012, suggesting that a new period of quiescence had been reestablished.

Rizzo, A.; Barberi, F.; Carapezza, M.; Di Piazza, A.; Francalanci, L.; Sortino, F.; D'Alessandro, W.

2013-12-01

385

Rare gases in lavas from the ultraslow spreading Lena Trough, Arctic Ocean  

NASA Astrophysics Data System (ADS)

Mid-ocean ridge basalts (MORB) from the Arctic Ocean have been much less studied than those from the Indian, Atlantic, and Pacific due to the difficulty of access related to ice cover. In 2001 and 2004 the Arctic ridges (Gakkel Ridge and Lena Trough) were intensively sampled. In this study we present the first helium, neon, and argon concentrations and isotopic ratios in a suite of samples from the ultraslow spreading Lena Trough (˜0.75 cm/yr effective full rate). Central Lena Trough (CLT) lavas display 4He/3He between 89,710 and 97,530 (R/Ra between 7.4 and 8.1), similar to the mean MORB ratio of 90,000 ± 10,000 (R/Ra = 8 ± 1). In a three neon isotope diagram, the samples fall on the MORB line, without showing any excess of nucleogenic 21Ne. The 40Ar/36Ar ratios vary from 349 to 6964. CLT samples have a typical MORB He and Ne isotopic composition. Rare gases do not indicate any mantle heterogeneities or contribution of subcontinental lithospheric mantle, although this has been suggested previously on the basis of the Sr-Nd and Pb isotopic systems. Based on noble gas systematics, a DUPAL-like anomaly is not observed in the Arctic Ocean. We propose two possible models which reconcile the rare gases with these previous studies. The first is that the Lena Trough mantle has a marble cake structure with small-scale heterogeneities (<1 km), allowing rapid diffusion and homogenization of rare gases compared to elements such as Sr, Nd, and Pb. The second model proposes that the recycled component identified by other isotopic systems was fully degassed at a recent date. It would therefore have a negligible mass budget of rare gases compared to other isotopic systems. This would suggest that the mantle enrichment beneath Lena Trough was generated by rift-forming processes and not by recycling.

Nauret, F.; Moreira, M.; Snow, J. E.

2010-06-01

386

H2O Nucleation Around Noble Metal Cations  

NASA Astrophysics Data System (ADS)

First principle electronic structure calculations have been carried out to investigate the ground state geometry, electronic structure and binding energy of noble metal cations (H2O)n^+ clusters containing up to 10 H2O molecules. The calculations are performed with the density functional theory code deMon2k [1]. Due to the very flat potential energy surface of these systems special care to the numerical stability of energy and gradient calculation must be taken.Comparison of the results obtained with Cu^+, Ag^+ and Au^+ will be shown. This investigation provides insight into the structural arrangement of the water molecules around these metals and a microscopic understanding of the observed incremental binding energy in the case of the gold cation based on collision induced dissociation experiments. [1] A.M. Köster, P. Calaminici, M.E. Casida, R. Flores-Moreno, G. Geudtner, A. Goursot, T. Heine, A. Ipatov, F. Janetzko, J. Martin del Campo, S. Patchkovski, J.U. Reveles, A. Vela and D.R. Salahub, deMon2k, The deMon Developers, Cinvestav, 2006

Calaminici, Patrizia; Oropeza Alfaro, Pavel; Juarez Flores, Martin; Köster, Andreas; Beltran, Marcela; Ulises Reveles, J.; Khanna, Shiv N.

2008-03-01

387

Noble Gas Measurement and Analysis Technique for Monitoring Reprocessing Facilities  

SciTech Connect

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.

Charlton, William S

1999-09-01

388

DISRUPTION MITIGATION WITH HIGH-PRESSURE NOBLE GAS INJECTION  

SciTech Connect

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.

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

389

Structural and dynamical behavior of noble-gas surfaces  

NASA Astrophysics Data System (ADS)

Molecular-dynamics calculations have been performed for noble-gas (krypton) surfaces. As pair potential between the particles, we used the potential of Barker et al. This potential is consistent with a wide range of experimental data and should be more realistic than the more familiar Lennard-Jones (6-12) potential. The calculations have been performed for temperatures of 7, 70, and 102 K. We used the following model: The krypton atoms are arranged as a slab-shaped fcc crystal, the two free surfaces being (100) planes. The slab consists of 11 layers of 50 atoms, i.e., the total number of particles used in the calculations was 550. The structure of the layers has been studied by means of the single-particle distribution function and the pair correlation function. Whereas the results for the innermost layer of the model agree well with the corresponding data of the bulk, there are relatively large effects for the outermost layer. This is also the case for the mean-square displacements , which is much larger in the outermost layer than in the bulk of the crystal. For T=102 K, we observe the effect of surface premelting: The outermost layer is disordered and the particles perform a diffusive motion parallel to the surface and the diffusion coefficient D is comparable to that in liquids. The effect of premelting in our system is obviously much more pronounced than in the case of Lennard-Jones systems.

Schommers, W.

1985-11-01

390

Laser-assisted biosynthesis for noble nanoparticles production  

NASA Astrophysics Data System (ADS)

Extracellular Biosynthesis technique (EBS) for nanoparticles production has attracted a lot of attention as an environmentally friendly and an inexpensive methodology. Our recent research was focused on the rapid approach of the green synthesis method and the reduction of the homogeneous size distribution of nanoparticles using pulse laser application. Noble nanoparticles (NNPs) were produced using various ethanol and water plant extracts. The plants were chosen based on their biomedical applications. The plants we used were Magnolia grandiflora, Geranium, Aloe `tingtinkie', Aloe barbadensis (Aloe Vera), Eucalyptus angophoroides, Sansevieria trifasciata, Impatiens scapiflora. Water and ethanol extract, were used as reducing agents to produce the nanoparticles. The reaction process was monitored using a UV-Visible spectroscopy. NNPs were characterized by Fourier Transfer Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), and the Dynamic Light Scattering technique (DLS). During the pulse laser Nd-YAG illumination (?=1064nm, 532nm, PE= 450mJ, 200mJ, 10 min) the blue shift of the surface plasmon resonance absorption peak was observed from ~424nm to 403nm for silver NP; and from ~530nm to 520 nm for gold NPs. In addition, NNPs solution after Nd-YAG illumination was characterized by the narrowing of the surface plasmon absorption resonance band, which corresponds to monodispersed NNPS distribution. FTIR, TEM, DLS, Zeta potential results demonstrated that NNPs were surrounded by biological molecules, which naturally stabilized nanosolutions for months. Cytotoxicity investigation of biosynthesized NNPs is in progress.

Kukhtarev, Tatiana; Edwards, Vernessa; Kukhtareva, Nickolai; Moses, Sherita

2014-08-01

391

Noble Metal-Membrane Composites for Electrochemical Applications  

NASA Astrophysics Data System (ADS)

Composite materials are a new class of materials that combine two or more separate components into a form suitable for structural applications. While each component retains its identity, the new composite material displays macroscopic properties superior to its parent constituents, particularly in terms of mechanical properties and economic value. Perhaps best known for their use in aerospace applications, advanced composites are also used by the automotive, biomedical, and sporting goods markets. In addition, these strong, stiff, lightweight materials are seeing increased use in the rehabilitation, repair, and retrofit of civil infrastructure, including, for example, as replacement bridge decks and wrapping for concrete columns. New composite materials presenting some interesting features which are not directly related to their mechanical properties are appearing. This is the case of noble metal-based polymeric composites, the preparation and characterization of which are considered in this article with regard to their electrochemical properties. These composites are of great practical interest because of potential applications in water electrolysis and H2-O2 fuel cells. Electrolyzers and fuel cells can be used for terrestrial transportation, oxygen generation in submarines, and energy conversion in spacecraft.

Millet, Pierre

1999-01-01

392

Thermal efficiency of the principal greenhouse gases  

NASA Astrophysics Data System (ADS)

Atmospheric gases are ranked according to the efficiency with which they absorb and radiate longwave radiation. The open international HITRAN database of gaseous absorption lines of high resolution together with inverse Fourier transform were used. The autocorrelation functions of the total dipole moment of the basic greenhouse gases molecules such as H2O, CO2, O3, N2O, and CH4 were obtained. Absorption coefficient spectra and emission power spectra of infrared radiation of these gases were calculated. Analysis of the emissive ability of all gases under consideration was carried out. Compared to CO2, all the gases under investigation have more effective emission except ozone. An efficiency criterion of IR absorption and emission is defined and is calculated for each studied gas, and the gases are ranked accordingly as follows (from strong to weak): H2O, CH4, CO2, N2O, and O3.

Y. Galashev, A.; R. Rakhmanova, O.

2015-01-01

393

Excitonic luminescence in the drift of excess electrons through liquid and solid rare gases  

NASA Astrophysics Data System (ADS)

It is shown that the excitation of electronic states is the main channel of energy loss of excess electrons drifting in moderate (?103V/cm) electric fields through condensed heavy rare gases (Rg). These losses, together with scattering on resonances of metastable negative ions (Rg*)-, determine the dependence of the average energy of the electrons and their drift velocity vd on the electric field E both in condensed Rg and in dense gases. In particular, explanations are given for the constancy of vd at large E and for the transformation of the electroluminescence spectrum upon changes in the density of heavy particles and their temperature. Thus it is predicted that localized excitons can be efficiently excited in the bulk of crystalline and liquid Xe, Kr, and Ar, with a yield of around 102 excitons (and UV photons) per electron.

Gordon, E. B.; Shestakov, A. F.

2001-09-01

394

Process for treating gases in the ammonia synthesis. [separation and dehydration of gases leaving synthesis reactor  

Microsoft Academic Search

In the synthesis of ammonia, a process is disclosed for treating the gases flowing from the synthesis reactor wherein those gases flow through a film absorber countercurrent to a cooled aqueous film to extract ammonia which is withdrawn as a strong solution from the absorber and scrubbed gases are combined for recycle with a stream of fresh feed which is

Guadalupi

1977-01-01

395

Fluorescence Imaging of Quantum Gases  

NASA Astrophysics Data System (ADS)

Quantum gases in optical lattices have proven a prolific platform to study condensed matter models such as the Bose-Hubbard model. The recently achieved in situ fluorescence imaging of low-dimensional systems has pushed the detection capabilities to a fully microscopic level. The method yields single-site and single-atom resolved images of the lattice gas in a single experimental run, thus giving direct access to fluctuations and correlation functions in the many-body system. These quantum gas microscopes have been used to study the superfluid-Mott insulator quantum phase transition at the single-atom level. Moreover, singlesite resolved addressing allows flipping the spin of individual atoms in a Mott insulator, thus deterministically creating local spin excitations whose dynamics can be observed. In this chapter, we will describe the implementation of the technique and discuss some of the obtained results.

Weitenberg, Christof

2015-09-01

396

Greenhouse Gases: The Overlooked Sources  

NSDL National Science Digital Library

This radio broadcast, which took place during the Kyoto Conference on global warming, discusses well-known and more obscure sources of greenhouse gases. Solutions to reduce carbon emissions are discussed, including creating fuel with less carbon in it (biomass fuels); reducing driving by increasing the cost of fuel; and improving vehicle fuel economy. The broadcast then introduces the topic of methane as a greenhouse gas; although less is emitted, it is about fifty times more effective than carbon dioxide at warming the planet. Cattle are a major source of methane; some ideas are introduced for monitoring and reducing their emissions. There is also discussion of whether global warming could be a result of natural variability as opposed to the result of a human-caused greenhouse effect. The broadcast is 49 minutes and 39 seconds in length.

397

Gases in agricultural slurry stores.  

PubMed

The evolution of gases during the handling of animal slurry was investigated at five sites. Particular attention was paid to the mixing and emptying operations since it is when performing these that personnel are most likely to be at risk of exposure. The main hazard was found to be high transient concentrations of hydrogen sulphide presenting in some cases a serious acute toxicity problem. Time-weighted average exposures did not generally indicate any long-term exposure risk. Other features noted were the evolution of ammonia and methane, although not at high levels, and some increase in the carbon dioxide concentration. Some reduction in oxygen concentration was measured, but generally the risk of poisoning by hydrogen sulphide was more serious than the risk of asphyxiation. PMID:2042881

Groves, J A; Ellwood, P A

1991-04-01

398

Energy Cascades in Granular Gases  

NASA Astrophysics Data System (ADS)

A new class of stationary states in granular gases where energy is transfered from large velocity scales to small velocity scales is found. These steady-states exist for arbitrary collision rules and arbitrary dimension. Their signature is a velocity distribution f(v) with an algebraic high-energy tail, f(v)˜v^-?. The exponent ? is obtained analytically and it varies continuously with the spatial dimension, the homogeneity index characterizing the collision rate, and the restitution coefficient. These stationary states are realized in numerical simulations in which energy is injected into the system by infrequently boosting particles to high velocities. It is proposed that these states may be realized experimentally in driven granular systems.

Ben-Naim, Eli

2005-03-01

399

Granular gases under extreme driving  

NASA Astrophysics Data System (ADS)

We study inelastic gases in two dimensions using event-driven molecular-dynamics simulations. Our focus is the nature of the stationary state attained by rare injection of large amounts of energy to balance the dissipation due to collisions. We find that under such extreme driving, with the injection rate much smaller than the collision rate, the velocity distribution has a power-law high-energy tail. The numerically measured exponent characterizing this tail is in excellent agreement with predictions of kinetic theory over a wide range of system parameters. We conclude that driving by rare but powerful energy injection leads to a well-mixed gas and constitutes an alternative mechanism for agitating granular matter. In this distinct nonequilibrium steady state, energy cascades from large to small scales. Our simulations also show that when the injection rate is comparable with the collision rate, the velocity distribution has a stretched exponential tail.

Kang, W.; Machta, J.; Ben-Naim, E.

2010-08-01

400

Continuous Processing with Mars Gases  

NASA Technical Reports Server (NTRS)

Current Martian missions call for the production of oxygen for breathing, and fuel and oxygen for propulsion to be produced from atmospheric carbon dioxide (CO2). Adsorption and freezing are the two methods considered for capturing CO, from the atmosphere. However, the nitrogen (N2) and argon (Ar), which make up less than 5 percent of the atmosphere, cause difficulties with both of these processes by blocking the CO2, This results in the capture process rapidly changing from a pressure driven process to a diffusion controlled process. To increase the CO, capture rates, some type of mechanical pump is usually proposed to remove the N2 and Ar. The N2 and Ar are useful and have been proposed for blanketing and pressurizing fuel tanks and as buffer gas for breathing air for manned missions. Separation of the Martian gases with the required purity can be accomplished with a combination of membranes. These membrane systems do not require a high feed pressure and provide suitable separation. Therefore, by use of the appropriate membrane combination with the Martian atmosphere supplied by a compressor a continuous supply of CO2 for fuel and oxygen production can be supplied. This phase of our program has focused on the selection of the membrane system. Since permeation data for membranes did not exist for Martian atmospheric pressures and temperatures, this information had to be compiled. The general trend as the temperature was lowered was for the membranes to become more selective. In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar. This paper will present the membrane data, provide the design requirements for a compressor, and compare the results with adsorption and freezer methods.

Parrish, Clyde; Jennings, Paul; Delgado, Hugo (Technical Monitor)

2001-01-01

401

Continuous Processing With Mars Gases  

NASA Technical Reports Server (NTRS)

Current Martian missions call for the production of oxygen for breathing, and fuel and oxygen for propulsion to be produced from atmospheric carbon dioxide (CO2). Adsorption and freezing are the two methods considered for capturing CO2 from the atmosphere. However, the nitrogen (N2) and argon (Ar), which make up less than 5 percent of the atmosphere, cause difficulties with both of these processes by blocking the CO2. This results in the capture process rapidly changing from a pressure driven process to a diffusion controlled process. To increase the CO2 capture rates, some type of mechanical pump is usually proposed to remove the N2 and Ar. The N2 and Ar are useful and have been proposed for blanketing and pressurizing fuel tanks and as buffer gas for breathing air for manned missions. Separation of the Martian gases with the required purity can be accomplished with a combination of membranes. These membrane systems do not require a high feed pressure and provide suitable separation. Therefore, by use of the appropriate membrane combination with the Martian atmosphere supplied by a compressor a continuous Supply Of CO2 for fuel and oxygen production can be supplied. This phase of our program has focused on the selection of the membrane system. Since permeation data for membranes did not exist for Martian atmospheric pressures and temperatures, this information had to be compiled. The general trend as the temperature was lowered was for the membranes to become more selective. In addition, the relative permeation rates between the three gases changed with temperature. The end result was to provide design parameters that could be used to separate CO2 from N2 and Ar. This paper will present the membrane data, provide the design requirements for a compressor, and compare the results with adsorption and freezer methods.

Parrish, Clyde; Jennings, Paul

2000-01-01

402

Liquefied Noble Gas (LNG) detectors for detection of nuclear materials  

NASA Astrophysics Data System (ADS)

Liquefied-noble-gas (LNG) detectors offer, in principle, very good energy resolution for both neutrons and gamma rays, fast response time (hence high-count-rate capabilities), excellent discrimination between neutrons and gamma rays, and scalability to large volumes. They do, however, need cryogenics. LNG detectors in sizes of interest for fissionable material detection in cargo are reaching a certain level of maturity because of the ongoing extensive R&}D effort in high-energy physics regarding their use in the search for dark matter and neutrinoless double beta decay. The unique properties of LNG detectors, especially those using Liquid Argon (LAr) and Liquid Xenon (LXe), call for a study to determine their suitability for Non-Intrusive Inspection (NII) for Special Nuclear Materials (SNM) and possibly for other threats in cargo. Rapiscan Systems Laboratory, Yale University Physics Department, and Adelphi Technology are collaborating in the investigation of the suitability of LAr as a scintillation material for large size inspection systems for air and maritime containers and trucks. This program studies their suitability for NII, determines their potential uses, determines what improvements in performance they offer and recommends changes to their design to further enhance their suitability. An existing 3.1 liter LAr detector (microCLEAN) at Yale University, developed for R&}D on the detection of weakly interacting massive particles (WIMPs) was employed for testing. A larger version of this detector (15 liters), more suitable for the detection of higher energy gamma rays and neutrons is being built for experimental evaluation. Results of measurements and simulations of gamma ray and neutron detection in microCLEAN and a larger detector (326 liter CL38) are presented.

Nikkel, J. A.; Gozani, T.; Brown, C.; Kwong, J.; McKinsey, D. N.; Shin, Y.; Kane, S.; Gary, C.; Firestone, M.

2012-03-01

403

Process for Making a Noble Metal on Tin Oxide Catalyst  

NASA Technical Reports Server (NTRS)

To produce a noble metal-on-metal oxide catalyst on an inert, high-surface-area support material (that functions as a catalyst at approximately room temperature using chloride-free reagents), for use in a carbon dioxide laser, requires two steps: First, a commercially available, inert, high-surface-area support material (silica spheres) is coated with a thin layer of metal oxide, a monolayer equivalent. Very beneficial results have been obtained using nitric acid as an oxidizing agent because it leaves no residue. It is also helpful if the spheres are first deaerated by boiling in water to allow the entire surface to be coated. A metal, such as tin, is then dissolved in the oxidizing agent/support material mixture to yield, in the case of tin, metastannic acid. Although tin has proven especially beneficial for use in a closed-cycle CO2 laser, in general any metal with two valence states, such as most transition metals and antimony, may be used. The metastannic acid will be adsorbed onto the high-surface-area spheres, coating them. Any excess oxidizing agent is then evaporated, and the resulting metastannic acid-coated spheres are dried and calcined, whereby the metastannic acid becomes tin(IV) oxide. The second step is accomplished by preparing an aqueous mixture of the tin(IV) oxide-coated spheres, and a soluble, chloride-free salt of at least one catalyst metal. The catalyst metal may be selected from the group consisting of platinum, palladium, ruthenium, gold, and rhodium, or other platinum group metals. Extremely beneficial results have been obtained using chloride-free salts of platinum, palladium, or a combination thereof, such as tetraammineplatinum (II) hydroxide ([Pt(NH3)4] (OH)2), or tetraammine palladium nitrate ([Pd(NH3)4](NO3)2).

Davis, Patricia; Miller, Irvin; Upchurch, Billy

2010-01-01

404

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

405

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

PubMed

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. PMID:25399144

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

2014-11-14

406

Signatures of spin-preserving symmetries in two-dimensional hole gases  

NASA Astrophysics Data System (ADS)

We investigate ramifications of the persistent spin helix symmetry in two-dimensional hole gases in the conductance of disordered mesoscopic systems. To this end we extend previous models by going beyond the axial approximation for III-V semiconductors. For heavy-hole subbands we identify an exact spin-preserving symmetry analogous to the electronic case by analyzing the crossover from weak antilocalization to weak localization and spin transmission as a function of extrinsic spin-orbit interaction strength.

Dollinger, Tobias; Kammermeier, Michael; Scholz, Andreas; Wenk, Paul; Schliemann, John; Richter, Klaus; Winkler, R.

2014-09-01

407

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

DOEpatents

A heavy metal poisoned, spent FCC catalyst is treated by chemically impregnating the poisoned catalyst with a new catalytic metal or metal salt to provide an attrition resistant catalyst or sorbent for a different catalytic or absorption processes, such as catalysts for Fischer-Tropsh Synthesis, and sorbents for removal of sulfur gasses from fuel gases and flue-gases. The heavy metal contaminated FCC catalyst is directly used as a support for preparing catalysts having new catalytic properties and sorbents having new sorbent properties, without removing or "passivating" the heavy metals on the spent FCC catalyst as an intermediate step.

Gangwal, Santosh (Cary, NC); Jothimurugesan, Kandaswamy (Hampton, VA)

1999-01-01

408

Predict thermal conductivities of pure gases  

Microsoft Academic Search

The programs presented for the TI-59 programmable calculator can determine the thermal conductivity of pure gases and gases at low pressures as well as the effect of pressure on conductivity. They are based on correlations by Eucken, Stiel-Thodos, Misic-Thodos, Roy-Thodos, and Redlich-Kwong.

1981-01-01

409

Rare Gases in the Chondrite Renazzo  

Microsoft Academic Search

A detailed analysis of the rare gas content of the chondrite Renazzo is presented. Fractions of different isotopic composition are separated by heating the sample to successively higher temperatures. The abundance and isotopic composition of the gases is similar to that in the carbonaceous chondrite Murray, with a high percentage of so-called primordial gas. For the light rare gases this

J. H. Reynolds; G. Turner

1964-01-01

410

Isotopic composition of gases from mud volcanoes  

SciTech Connect

A study has been made of the isotopic composition of the carbon in methane and carbon dioxide, as well as hydrogen in the methane, in the gases of mud volcanoes, for all main mud volcano areas in the USSR. The isotopic composition of carbon and hydrogen in methane shows that the gases resemble those of oil and gas deposits, while carbon dioxide of these volcanoes has a heavier isotopic composition with a greater presence of ''ultraheavy'' carbon dioxide. By the chemical and isotopic composition of gases, Azerbaidzhan and South Sakhalin types of mud volcano gases have been identified, as well as Bulganak subtypes and Akhtala and Kobystan varieties. Correlations are seen between the isotopic composition of gases and the geological build of mud volcano areas.

Valysaev, B.M.; Erokhin, V.E.; Grinchenko, Y.I.; Prokhorov, V.S.; Titkov, G.A.

1985-09-01

411

Calibration of cosmogenic noble gas production in ordinary chondrites based on 36Cl-36Ar ages. Part 1: Refined produced rates for cosmogenic 21Ne and 38Ar  

NASA Astrophysics Data System (ADS)

We measured the concentrations and isotopic compositions of He, Ne, and Ar in bulk samples and metal separates of 14 ordinary chondrite falls with long exposure ages and high metamorphic grades. In addition, we measured concentrations of the cosmogenic radionuclides 10Be, 26Al, and 36Cl in metal separates and in the nonmagnetic fractions of the selected meteorites. Using cosmogenic 36Cl and 36Ar measured in the metal separates, we determined 36Cl-36Ar cosmic-ray exposure (CRE) ages, which are shielding-independent and therefore particularly reliable. Using the cosmogenic noble gases and radionuclides, we are able to decipher the CRE history for the studied objects. Based on the correlation 3He/21Ne versus 22Ne/21Ne, we demonstrate that, among the meteorites studied, only one suffered significant diffusive losses (about 35%). The data confirm that the linear correlation 3He/21Ne versus 22Ne/21Ne breaks down at high shielding. Using 36Cl-36Ar exposure ages and measured noble gas concentrations, we determine 21Ne and 38Ar production rates as a function of 22Ne/21Ne. The new data agree with recent model calculations for the relationship between 21Ne and 38Ar production rates and the 22Ne/21Ne ratio, which does not always provide unique shielding information. Based on the model calculations, we determine a new correlation line for 21Ne and 38Ar production rates as a function of the shielding indicator 22Ne/21Ne for H, L, and LL chondrites with preatmospheric radii less than about 65 cm. We also calculated the 10Be/21Ne and 26Al/21Ne production rate ratios for the investigated samples, which show good agreement with recent model calculations.

Dalcher, N.; Caffee, M. W.; Nishiizumi, K.; Welten, K. C.; Vogel, N.; Wieler, R.; Leya, I.

2013-10-01

412

Laser Cooling of Dense Rubidium-Noble Gas Mixtures via Collisional Redistribution of Radiation  

E-print Network

We describe experiments on the laser cooling of both helium-rubidium and argon-rubidium gas mixtures by collisional redistribution of radiation. Frequent alkali-noble gas collisions in the ultradense gas, with typically 200\\,bar of noble buffer gas pressure, shift a highly red detuned optical beam into resonance with a rubidium D-line transition, while spontaneous decay occurs close to the unshifted atomic resonance frequency. The technique allows for the laser cooling of macroscopic ensembles of gas atoms. The use of helium as a buffer gas leads to smaller temperature changes within the gas volume due to the high thermal conductivity of this buffer gas, as compared to the heavier argon noble gas, while the heat transfer within the cell is improved.

Vogl, Ulrich; Weitz, Martin; 10.1117/12.905897

2012-01-01

413

Dissociation dynamics of noble-gas dimers in intense two-color IR laser fields  

NASA Astrophysics Data System (ADS)

We numerically model the dissociation dynamics of the noble-gas dimer ions He2+, Ne2+, Ar2+, Kr2+, and Xe2+ in ultrashort pump and probe laser pulses of different wavelengths. Our calculations reveal a distinguished “gap” in the kinetic energy spectra, observed experimentally for the Ar2 dimer [J. Wu , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.110.033005 110, 033005 (2013)], for all noble-gas dimers for appropriate wavelength combinations. This striking phenomenon can be explained by the dissociation of dimer ions on dipole-coupled Born-Oppenheimer adiabatic potential curves. Comparing pump-probe-pulse-delay-dependent kinetic-energy-release spectra for different noble-gas dimer cations of increasing mass, we discuss increasingly prominent (i) fine-structure effects in and (ii) classical aspects of the nuclear vibrational motion.

Magrakvelidze, M.; Thumm, U.

2013-07-01

414

An RF-only ion-funnel for extraction from high-pressure gases  

E-print Network

An RF ion-funnel technique has been developed to extract ions from a high-pressure (10 bar) noble-gas environment into vacuum ($10^{-6}$ mbar). Detailed simulations have been performed and a prototype has been developed for the purpose of extracting $^{136}$Ba ions from Xe gas with high efficiency. With this prototype, ions have been extracted for the first time from high-pressure xenon gas and argon gas. Systematic studies have been carried out and compared to the simulations. This demonstration of extraction of ions with mass comparable to that of the gas generating the high-pressure into vacuum has applications to Ba tagging from a Xe-gas time-projection chamber (TPC) for double beta decay as well as to the general problem of recovering trace amounts of an ionized element in a heavy (m$>40$ u) carrier gas.

Thomas Brunner; Daniel Fudenberg; Victor Varentsov; Amanda Sabourov; Giorgio Gratta; Jens Dilling; Ralph DeVoe; David Sinclair; William Fairbank Jr.; Joshua B Albert; David J Auty; Phil S Barbeau; Douglas Beck; Cesar Benitez-Medina; Martin Breidenbach; Guofu F Cao; Christopher Chambers; Bruce Cleveland; Matthew Coon; Adam Craycraft; Timothy Daniels; Sean J Daugherty; Tamar Didberidze; Michelle J Dolinski; Matthew Dunford; Lorenzo Fabris; Jacques Farine; Wolfhart Feldmeier; Peter Fierlinger; Razvan Gornea; Kevin Graham; Mike Heffner; Mitchell Hughes; Michael Jewell; Xiaoshan S Jiang; Tessa N Johnson; Sereres Johnston; Alexander Karelin; Lisa J Kaufman; Ryan Killick; Thomas Koffas; Scott Kravitz; Reiner Kruecken; Alexey Kuchenkov; Krishna S Kumar; Douglas S Leonard; Francois Leonard; Caio Licciardi; Yi-Hsuan H Lin; Jiajie Ling; Ryan MacLellan; Michael G Marino; Brian Mong; David Moore; Allen Odian; Igor Ostrovskiy; Christian Ouellet; Andreas Piepke; Andrea Pocar; Fabrice Retiere; Peter C Rowson; Maria P Rozo; Alexis Schubert; Erica Smith; Victor Stekhanov; Michal Tarka; Tamer Tolba; Delia Tosi; Karl Twelker; Jean-Luc L Vuilleumier; Josiah Walton; Timothy Walton; Manuel Weber; Liangjian J Wen; Ubi Wichoski; Liang Yang; Yung-Ruey Yen

2014-12-03

415

Noble-metal mineralization in olivine clinopyroxenite within idgimskiy gabbro-peridotite-pyroxenite complex (West Sayan Mountains)  

NASA Astrophysics Data System (ADS)

The study of noble-metal mineralization in olivine clinopyroxenite within idgimsky gabbro- peridotite-pyroxenite complex was carried out. Palladium minerals were identified: palladium telluride and palladium and platinum telluride with mercury impurity. The discovered noble- metal mineralization in olivine clinopyroxenites suggests the presence of perspective low sulfidation platinemetal mineralization in mafic within Verkhne-Amyl ore field.

Cherkasova, T. Y.; Korotchenko, T. V.

2014-08-01

416

A GREEN CHEMISTRY APPROACH TO PREPARATION OF CORE (FE OR CU)-SHELL (NOBLE METALS) NANOCOMPOSITES USING AQUEOUS ASCORBIC ACID  

EPA Science Inventory

A greener method to fabricate novel core (Fe or Cu)-shell (noble metals) nanocomposites of transition metals such as Fe and Cu and noble metals such as Au, Pt, Pd, and Ag using aqueous ascorbic acid is described. Transition metal salts such as Cu and Fe were reduced using ascor...

417

Method and apparatus for noble gas atom detection with isotopic selectivity  

DOEpatents

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