WorldWideScience

Sample records for atomic gas lines

  1. Detection of water molecules in inert gas based plasma by the ratios of atomic spectral lines

    Science.gov (United States)

    Bernatskiy, A. V.; Ochkin, V. N.

    2017-01-01

    A new approach is considered to detect the water leaks in inert plasma-forming gas present in the reactor chamber. It is made up of the intensity ratio of D α and H α spectral lines in combination with O, Ar and Xe lines intensity. The concentrations of H2O, O, H and D particles have been measured with high sensitivity. At the D2 admixture pressure {{p}{{\\text{D}\\text{2}}}}   =  0.025 mbar, we used the acquisition time of 10 s to measure the rate of water molecules injected from the outside, Γ0  =  1.4 · 10-9 mbar · m3 · s-1, and the incoming water molecules to plasma, Γ  =  5 ·10-11 mbar · m3 · s-1. The scaling proves that at small D2 admixtures (10-4 mbar), the leaks with the rates Γ0  ≈  6 · 10-12 mbar · m3 · s-1 and Γ  ≈  2 · 10-13 mbar · m3 · s-1 can be detected and measured. The difference between Γ0 and Γ values is due to the high degree of H2O dissociation, which can be up to 97-98%.

  2. Gas temperature determination in an argon non-thermal plasma at atmospheric pressure from broadenings of atomic emission lines

    Science.gov (United States)

    Yubero, C.; Rodero, A.; Dimitrijevic, M. S.; Gamero, A.; García, M. C.

    2017-03-01

    In this work a new spectroscopic method, allowing gas temperature determination in argon non-thermal plasmas sustained at atmospheric pressure, is presented. The method is based on the measurements of selected pairs of argon atomic lines (Ar I 603.2 nm/Ar I 549.6 nm, Ar I 603.2 nm/Ar I 522.1 nm, Ar I 549.6 nm/Ar I 522.1 nm). For gas temperature determination using the proposed method, there is no need of knowing the electron density, neither making assumptions on the degree of thermodynamic equilibrium existing in the plasma. The values of the temperatures obtained using this method, have been compared with the rotational temperatures derived from the OH ro-vibrational bands, using both, the well-known Boltzmann-plot technique and the best fitting to simulated ro-vibrational bands. A very good agreement has been found.

  3. Data correlation in on-line solid-phase extraction-gas chromatography-atomic emission/mass spectrometric detection of unknown microcontaminants

    NARCIS (Netherlands)

    Hankemeier, Th.; Rozenbrand, J.; Abhadur, M.; Vreuls, J.J.; Brinkman, U.A.Th.

    1998-01-01

    A procedure is described for the (non-target) screening of hetero-atom-containing compounds in tap and waste water by correlating data obtained by gas chromatography (GC) using atomic emission (AED) and mass selective (MS) detection. Solid-phase extraction (SPE) was coupled on-line to both GC system

  4. The outflow of gas from the Centaurus A circumnuclear disk: atomic spectral line maps from Herschel-PACS and APEX

    CERN Document Server

    Israel, F P; Meijerink, R; Requena-Torres, M A; Stutzki, J

    2016-01-01

    The physical state of the gas in the central 500 pc of NGC~5128 (the radio galaxy Centaurus A - Cen A), was investigated using the far-infrared fine-structure lines of carbon, oxygen, and nitrogen, as well as the CO(4-3) molecular line. The circumnuclear disk (CND) is traced by emission from dust and the neutral gas ([CI] and CO). A gas outflow with a line-of-sight velocity of 60 km/s is evident in both species. The center of the CND is bright in [OI], [OIII], and [CII]; [OI]63mu emission dominates that of [CII] even though it is absorbed with optical depths of 1.0-1.5. The outflow is well-traced by the [NII] and [NIII] lines and also seen in the [CII] and [OIII] lines that peak in the center. Ionized gas densities are moderate in the CND and low everywhere else. Neutral gas densities range from 4000 per cm3 (outflow, extended thin disk ETD) to 20 000 per cm3 (CND). The CND radiation field is weak compared to the ETD starburst field. The outflow has a much stronger radiation field. The total mass of all the C...

  5. The outflow of gas from the Centaurus A circumnuclear disk. Atomic spectral line maps from Herschel/PACS and APEX

    Science.gov (United States)

    Israel, F. P.; Güsten, R.; Meijerink, R.; Requena-Torres, M. A.; Stutzki, J.

    2017-02-01

    The physical state of the gas in the central 500 pc of NGC 5128 (the radio galaxy Centaurus A), was investigated using the fine-structure lines of carbon [CI], [CII]; oxygen [OI], [OIII], and nitrogen [NII], [NIII] as well as the 12CO(4-3) molecular line. The circumnuclear disk (CND) is traced by emission from dust and the neutral gas ([CI] and 12CO). A gas outflow with a line-of-sight velocity of 60 km s-1 is evident in both lines. The [CI] emission from the CND is unusually strong with respect to that from CO. The center of the CND (R mass of all the CND gas is 9.1 ± 0.9×107M⊙ but the mass of the outflowing gas is only 15-30% of that. The outflow most likely originates from the shock-dominated CND cavity surrounding the central black hole. With a factor of three uncertainty, the mass outflow rate is ≈ 2 M⊙ yr-1, a thousand times higher than the accretion rate of the black hole. Without replenishment, the CND will be depleted in 15-120 million years. However, the outflow velocity is well below the escape velocity.

  6. GRB 980425 host: [CII], [OI] and CO lines reveal recent enhancement of star formation due to atomic gas inflow

    CERN Document Server

    Michałowski, Michał J; Wardlow, J L; Karska, A; Messias, H; van der Werf, P; Hunt, L K; Baes, M; Castro-Tirado, A J; Gentile, G; Hjorth, J; Floc'h, E Le; Martinez, R Perez; Guelbenzu, A Nicuesa; Rasmussen, J; Rizzo, J R; Rossi, A; Sanchez-Portal, M; Schady, P; Sollerman, J; Xu, D

    2016-01-01

    We have recently suggested that gas accretion can be studied using host galaxies of gamma-ray bursts (GRBs). We obtained the first ever far-infrared (FIR) line observations of a GRB host, namely Herschel/PACS resolved [CII] 158 um and [OI] 63 um spectroscopy, as well as APEX CO(2-1) and ALMA CO(1-0) observations of the GRB 980425 host. It has elevated [CII]/FIR and [OI]/FIR ratios and higher values of star formation rate (SFR) derived from line ([CII], [OI], Ha) than from continuum (UV, IR, radio) indicators. [CII] emission exhibits a normal morphology, peaking at the galaxy center, whereas [OI] is concentrated close to the GRB position and the nearby Wolf-Rayet region. The high [OI] flux indicates high radiation field and gas density. The [CII]/CO luminosity ratio of the GRB 980425 host is close to the highest values found for local star-forming galaxies. Its CO-derived molecular gas mass is low given its SFR and metallicity, but the [CII]-derived molecular gas mass is close to the expected value. The [OI] a...

  7. Effect of atomization gas pressure variation on gas flow field in supersonic gas atomization

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper, a computational fluid flow model was adopted to investigate the effect of varying atomization gas pressure (P0) on the gas flow field in supersonic gas atomization. The influence of P0 on static pressure and velocity magnitude of the central axis of the flow field was also examined. The numerical results indicate that the maximum gas velocity within the gas field increases with increasing P0. The aspiration pressure (ΔP) is found to decrease as P0 increases at a lower atomization gas pressure. However, at a higher atomization gas pressure increasing P0 causes the opposite: the higher atomization gas pressure, the higher aspiration pressure. The alternation of ΔP is caused by the variations of stagnation point pressure and location of Mach disk, while hardly by the location of stagnation point. A radical pressure gradient is formed along the tip of the delivery tube and increases as P0 increases.

  8. Atomic gas in debris discs

    Science.gov (United States)

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

    2017-04-01

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

  9. Vortex line in spin-orbit coupled atomic Fermi gases

    OpenAIRE

    2012-01-01

    PHYSICAL REVIEW A 85, 013622 (2012) Vortex line in spin-orbit coupled atomic Fermi gases M. Iskin Department of Physics, Koc¸ University, Rumelifeneri Yolu, TR-34450 Sariyer, Istanbul, Turkey (Received 1 December 2011; published 17 January 2012) It has recently been shown that the spin-orbit coupling gives rise to topologically nontrivial and thermodynamically stable gapless superfluid phases when the pseudospin populations of an atomic Fermi gas are imbalanced, with the ...

  10. Inflow of atomic gas fuelling star formation

    DEFF Research Database (Denmark)

    Michałowski, M. J.; Gentile, G.; Hjorth, Jeppe;

    2016-01-01

    Gamma-ray burst host galaxies are deficient in molecular gas, and show anomalous metal-poor regions close to GRB positions. Using recent Australia Telescope Compact Array (ATCA) Hi observations we show that they have substantial atomic gas reservoirs. This suggests that star formation in these ga......Gamma-ray burst host galaxies are deficient in molecular gas, and show anomalous metal-poor regions close to GRB positions. Using recent Australia Telescope Compact Array (ATCA) Hi observations we show that they have substantial atomic gas reservoirs. This suggests that star formation...... in these galaxies may be fuelled by recent inflow of metal-poor atomic gas. While this process is debated, it can happen in low-metallicity gas near the onset of star formation because gas cooling (necessary for star formation) is faster than the Hi-to-H2 conversion....

  11. Rubidium atomic line filtered (RALF) Doppler velocimetry

    Science.gov (United States)

    Fajardo, Mario E.; Molek, Christopher D.; Vesely, Annamaria L.

    2017-01-01

    We report recent improvements to our Rubidium Atomic Line Filtered (RALF) Doppler velocimetry apparatus [M.E. Fajardo, C.D. Molek, and A.L. Vesely, J. Appl. Phys. 118, 144901 (2015)]. RALF is a high-velocity and high-acceleration adaptation of the Doppler Global Velocimetry method for measuring multi-dimensional velocity vector flow fields, which was developed in the 1990s by aerodynamics researchers [H. Komine, U.S. Patent #4,919,536]. Laser velocimetry techniques in common use within the shock physics community (e.g. VISAR, Fabry-Pérot, PDV) decode the Doppler shift of light reflected from a moving surface via interference phenomena. In contrast, RALF employs a completely different physical principle: the frequency-dependent near-resonant optical transmission of a Rb/N2 gas cell, to encode the Doppler shift of reflected λ0 ≈ 780.24 nm light directly onto the transmitted light intensity. Thus, RALF is insensitive to minor changes to the optical pathlengths and transit times of the Doppler shifted light, which promises a number of practical advantages in imaging velocimetry applications. The single-point RALF proof-of-concept apparatus described here is fiber optic based, and our most recent modifications include the incorporation of a larger bandwidth detection system, and a second 780 nm laser for simultaneous upshifted-PDV (UPDV) measurements. We report results for the laser driven launch of a 10-μm-thick aluminum flyer which show good agreement between the RALF and UPDV velocity profiles, within the limitations of the admittedly poor signal:noise ratio (SNR) RALF data.

  12. Spectral line intensity and polarization in gas-dusty medium

    CERN Document Server

    Silant'ev, N A; Novikov, V V

    2016-01-01

    It is assumed that in Seyfert galaxies the gas-dusty medium exits near the centre in the form of a molecular and dusty torus and equatorial flow. These objects have spectral lines emission of hydrogen, helium and other atoms. We derived the spectral line radiative transfer equation for such media. This equation has dimensionless extinction factor of the form: $\\alpha(\

  13. Inert gas atomization of chemical grade silicon

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, D.; Ferreira Neto, J.B.; Salgado, L.; Nogueira, P.F.; Poco, J.G.R. [Metallurgy Div. Cidade Univ., Inst. for Technological Research, Sao Paulo, SP (Brazil)

    2001-07-01

    The use of inert gas atomization to obtain chemical grade silicon particles was investigated. Both cooling rate and chemical composition are very important regarding a tailored microstructure, related with silicon performance during the synthesis of the silanos, an intermediary raw material in the silicone production. Previously refined silicon was used as raw material. Silicon with different aluminum contents were atomized and analyzed. The atomization temperature was set around 1520 C, and it was used a confined atomization nozzle. It was necessary to use a long atomization chamber to allow the cooling of the coarse silicon particles. After atomization, the powder was characterized and classified. The coarse fraction was milled. Two different particle size groups (different cooling rates) and the as atomized particles were investigated. The chemical behavior during the synthesis of the silanos was analyzed in a laboratory reactor. The relationship between cooling rate, aluminum content and silicon performance during the silanos synthesis is discussed. (orig.)

  14. Infrared [Fe II] Emission Lines from Radiative Atomic Shocks

    CERN Document Server

    Koo, Bon-Chul; Kim, Hyun-Jeong

    2016-01-01

    [Fe II] emission lines are prominent in the infrared (IR), and they are important diagnostic tools for radiative atomic shocks. We investigate the emission characteristics of [Fe II] lines using a shock code developed by Raymond (1979) with updated atomic parameters. We first review general characteristics of IR [Fe II] emission lines from shocked gas, and derive [Fe II] line fluxes as a function of shock speed and ambient density. We have compiled the available IR [Fe II] line observations of interstellar shocks and compare them to the ratios predicted from our model. The sample includes both young and old supernova remnants in the Galaxy and the Large Magellanic Cloud and several Herbig-Haro objects. We find that the observed ratios of IR [Fe II] lines generally fall on our grid of shock models, but the ratios of some mid-infrared lines, e.g., [Fe II] 35.35 um/[Fe II] 25.99 um, [Fe II] 5.340 um/[Fe II] 25.99 um, and [Fe II] 5.340 um/[Fe II] 17.94 um, are significantly offset from our model grid. We discuss ...

  15. The absorptive line shape of hadronic atoms

    CERN Document Server

    Ericson, Torleif Eric Oskar

    1977-01-01

    The exact line shape for all energies is derived analytically in the limit of negligible nuclear dimensions. The shape deviates from the Breit-Wigner form. The high-energy tail of the line has a universal shape, independent of the absorptive strength. The tails are different for different initial states, however. The integrated line strength diverges logarithmically. Renormalization of the hadron wavefunction by strong interactions leads to the usual shape near resonance and restores convergence for very large energies. The results resolve a logical inconsistency in the normal analysis of hadronic atoms and are of practical importance. It is shown that bound hadronic states (e.g. Y/sub 0/*) give natural contributions in the high energy region. Numerical illustrations are given. (6 refs).

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

    Science.gov (United States)

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

    1986-01-01

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

  17. GRB 980425 host: [C II], [O I], and CO lines reveal recent enhancement of star formation due to atomic gas inflow

    DEFF Research Database (Denmark)

    Michałowski, M. J.; Castro Cerón, J. M.; Wardlow, J. L.;

    2016-01-01

    in the closest galaxy hosting a GRB (980425). Methods. We obtained the first ever far-infrared (FIR) line observations of a GRB host, namely Herschel/PACS resolved [C ii] 158 μm and [O i] 63 μm spectroscopy, and an APEX/SHeFI CO(2-1) line detection and ALMA CO(1-0) observations of the GRB 980425 host. Results...

  18. Quantum Gas Microscope for Fermionic Atoms

    Science.gov (United States)

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

    2016-05-01

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

  19. The Physical Conditions of Atomic Gas at High Redshift

    Science.gov (United States)

    Neeleman, Marcel

    In this thesis we provide insight into the chemical composition, physical conditions and cosmic distribution of atomic gas at high redshift. We study this gas in absorption against bright background quasars in absorption systems known as Damped Ly-alpha Systems (DLAs). These systems contain the bulk of the atomic gas at high redshift and are the likely progenitors of modern-day galaxies. In Chapter 2, we find that the atomic gas in DLAs obeys a mass-metallicity relationship that is similar to the mass-metallicity relationship seen in star-forming galaxies. The evolution of this relationship is linear with redshift, allowing for a planar equation to accurately describe this evolution, which provides a more stringent constraint on simulations modeling DLAs. Furthermore, the concomitant evolution of the mass-metallicity relationship of atomic gas and star-forming galaxies suggests an intimate link between the two. We next use a novel way to measure the physical conditions of the gas by using fine-structure line ratios of singly ionized carbon and silicon. By measuring the density of the upper and lower level states, we are able to determine the temperature, hydrogen density and electron density of the gas. We find that the conditions present in this high redshift gas are consistent with the conditions we see in the local interstellar medium (ISM). A few absorbers have higher than expected pressure, which suggests that they probe the ISM of star-forming galaxies. Finally in Chapter 4, we measure the cosmic neutral hydrogen density at redshifts below 1.6. Below this redshift, the Ly-alpha line of hydrogen is absorbed by the atmosphere, making detection difficult. Using the archive of the Hubble Space Telescope, we compile a comprehensive list of quasars for a search of DLAs at redshift below 1.6. We find that the incidence rate of DLAs and the cosmic neutral hydrogen density is smaller than previously measured, but consistent with the values both locally and at

  20. Positronium collisions with rare-gas atoms

    CERN Document Server

    Gribakin, G F; Wilde, R S; Fabrikant, I I

    2015-01-01

    We calculate elastic scattering of positronium (Ps) by the Xe atom using the recently developed pseudopotential method [Fabrikant I I and Gribakin G F 2014 Phys. Rev. A 90 052717] and review general features of Ps scattering from heavier rare-gas atoms: Ar, Kr and Xe. The total scattering cross section is dominated by two contributions: elastic scattering and Ps ionization (break-up). To calculate the Ps ionization cross sections we use the binary-encounter method for Ps collisions with an atomic target. Our results for the ionization cross section agree well with previous calculations carried out in the impulse approximation. Our total Ps-Xe cross section, when plotted as a function of the projectile velocity, exhibits similarity with the electron-Xe cross section for the collision velocities higher than 0.8 a.u., and agrees very well with the measurements at Ps velocities above 0.5 a.u.

  1. Observations of Absorption Lines from Highly Ionized Atoms

    Science.gov (United States)

    Jenkins, E. B.

    1984-01-01

    In the ultraviolet spectra of hot stars, absorption lines can be seen from highly ionized species in the interstellar medium. Observations of these features which have been very influential in revising the perception of the medium's various physical states, are discussed. The pervasiveness of O 6 absorption lines, coupled with complementary observations of a diffuse background in soft X-rays and EUV radiation, shows that there is an extensive network of low density gas (n approx. fewX 0.001/cucm) existing at coronal temperatures, 5.3 or = log T or = 6.3. Shocks created by supernova explosions or mass loss from early-type stars can propagate freely through space and eventually transfer a large amount of energy to the medium. To create the coronal temperatures, the shocks must have velocities in excess of 150 km/sec; shocks at somewhat lower velocity 9v or = 100 km/sec) can be directly observed in the lines of Si3. Observations of other lines in the ultraviolet, such as Si 4V and C 5, may highlight the widespread presence of energetic uv radiation from very hot, dward stars. More advanced techniques in visible and X-ray astronomical spectroscopy may open up for inspection selected lines from atoms in much higher stages of ionization.

  2. Evidence for the Heating of Atomic Interstellar Gas by PAHs

    CERN Document Server

    Helou, G; Hollenbach, D J; Dale, D A; Contursi, A; Helou, George; Malhotra, Sangeeta; Hollenbach, David J.; Dale, Daniel A.; Contursi, Alessandra

    2001-01-01

    We report a strong correlation between the [CII] 158 micron cooling line and the mid-infrared flux in the 5-10 micron range in a wide variety of star-forming galaxies. The mid-infrared flux is dominated by Aromatic Feature Emission (AFE), which is thought to arise from large polycyclic aromatic hydrocarbon molecules or `PAHs' and generally associated with the smallest interstellar grains. The [CII] line is the dominant gas coolant in most regions of atomic interstellar gas, and therefore reflects the heating input to the gas. The ratio of these two quantities, [CII]/AFE, remains nearly constant with the ratio of the IRAS 60 micron band flux to the 100 micron band flux, R(60/100). This is in contrast to the drop in the [CII]/FIR ratio with increasing R(60/100), which signal higher dust temperatures and more intense radiation fields. We interpret the stable [CII]/AFE ratio as evidence that gas heating is dominated by the PAHs or small grains which are also AFE carriers over a wide range of conditions. The trend...

  3. Creation of ultracold molecules from a Fermi gas of atoms

    OpenAIRE

    2003-01-01

    Since the realization of Bose-Einstein condensates (BEC) in atomic gases an experimental challenge has been the production of molecular gases in the quantum regime. A promising approach is to create the molecular gas directly from an ultracold atomic gas; for example, atoms in a BEC have been coupled to electronic ground-state molecules through photoassociation as well as through a magnetic-field Feshbach resonance. The availability of atomic Fermi gases provides the exciting prospect of coup...

  4. Powder Size and Distribution in Ultrasonic Gas Atomization

    Science.gov (United States)

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

    1985-08-01

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

  5. A sapphire tube atomizer for on-line atomization and in situ collection of bismuthine for atomic absorption spectrometry

    OpenAIRE

    Musil, S. (Stanislav); Dědina, J. (Jiří)

    2013-01-01

    Sapphire was tested as a new material for volatile species atomizers and bismuthine was chosen as a convenient model for volatile species. Its performance was compared with a quartz atomizer in both modes of operation - on-line atomization versus in situ collection.

  6. Atomic Spectral Line Broadening Bibliographic Database Physical Reference Data

    CERN Document Server

    Fuhr, J; National Institute of Standards and Technology. Gaithersburg

    This database contains approximately 800 recent references. These papers contain numerical data, general information, comments, and review articles and are part of the collection of the Data Center on Atomic Line Shapes and Shifts at NIST.

  7. Evolution of the atomic and molecular gas content of galaxies

    NARCIS (Netherlands)

    Popping, Gergö; Somerville, Rachel S.; Trager, Scott C.

    2014-01-01

    We study the evolution of atomic and molecular gas in galaxies in semi-analytic models of galaxy formation that include new modelling of the partitioning of cold gas in galactic discs into atomic, molecular, and ionized phases. We adopt two scenarios for the formation of molecules: one pressure base

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

    Science.gov (United States)

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

    1988-01-01

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

  9. Gas lasers applied atomic collision physics, v.3

    CERN Document Server

    McDaniel, E W

    1982-01-01

    Applied Atomic Collision Physics, Volume 3: Gas Lasers describes the applications of atomic collision physics in the development of many types of gas lasers. Topics covered range from negative ion formation in gas lasers to high-pressure ion kinetics and relaxation of molecules exchanging vibrational energy. Ion-ion recombination in high-pressure plasmas is also discussed, along with electron-ion recombination in gas lasers and collision processes in chemical lasers.Comprised of 14 chapters, this volume begins with a historical summary of gas laser developments and an overview of the basic ope

  10. Radio recombination lines from the largest bound atoms in space

    CERN Document Server

    Stepkin, S V; Kantharia, N G; Shankar, N U

    2006-01-01

    In this paper, we report the detection of a series of radio recombination lines (RRLs) in absorption near 26 MHz arising from the largest bound carbon atoms detected in space. These atoms, which are more than a million times larger than the ground state atoms are undergoing delta transitions (n~1009, Delta n=4) in the cool tenuous medium located in the Perseus arm in front of the supernova remnant, Cassiopeia A. Theoretical estimates had shown that atoms which recombined in tenuous media are stable up to quantum levels n~1500. Our data indicates that we have detected radiation from atoms in states very close to this theoretical limit. We also report high signal-to-noise detections of alpha, beta and gamma transitions in carbon atoms arising in the same clouds. In these data, we find that the increase in line widths with quantum number (proportional to n^5) due to pressure and radiation broadening of lines is much gentler than expected from existing models which assume a power law background radiation field. T...

  11. Transmission-line decelerators for atoms in high Rydberg states

    CERN Document Server

    Lancuba, P

    2014-01-01

    Beams of helium atoms in Rydberg states with principal quantum number $n=52$, and traveling with an initial speed of 1950 m/s, have been accelerated, decelerated and guided while confined in moving electric traps generated above a curved, surface-based electrical transmission line with a segmented center conductor. Experiments have been performed with atoms guided at constant speed, and with accelerations exceeding $10^7$ m/s$^2$. In each case the manipulated atoms were detected by spatially resolved, pulsed electric field ionization. The effects of tangential and centripetal accelerations on the effective trapping potentials experienced by the atoms in the decelerator have been studied, with the resulting observations highlighting contributions from the density of excited Rydberg atoms to the acceleration, deceleration and guiding efficiencies in the experiments.

  12. Transmission-line decelerators for atoms in high Rydberg states

    Science.gov (United States)

    Lancuba, P.; Hogan, S. D.

    2014-11-01

    Beams of helium atoms in Rydberg states with principal quantum number n =52 , and traveling with an initial speed of 1950 m/s, have been accelerated, decelerated, and guided while confined in moving electric traps generated above a curved, surface-based electrical transmission line with a segmented center conductor. Experiments have been performed with atoms guided at constant speed, and with accelerations exceeding 107 m /s 2. In each case, the manipulated atoms were detected by spatially resolved, pulsed electric field ionization. The effects of tangential and centripetal accelerations on the effective trapping potentials experienced by the atoms in the decelerator have been studied, with the resulting observations highlighting contributions from the density of excited Rydberg atoms to the acceleration, deceleration, and guiding efficiencies in the experiments.

  13. Molecular and atomic gas along and across the main sequence of star-forming galaxies

    Science.gov (United States)

    Saintonge, Amelie; Catinella, Barbara; Cortese, Luca; Genzel, Reinhard; Giovanelli, Riccardo; Haynes, Martha P.; Janowiecki, Steven; Kramer, Carsten; Lutz, Katharina A.; Schiminovich, David; Tacconi, Linda J.; Wuyts, Stijn; Accurso, Gioacchino

    2016-10-01

    We use spectra from the ALFALFA, GASS and COLD GASS surveys to quantify variations in the mean atomic and molecular gas mass fractions throughout the SFR-M* plane and along the main sequence (MS) of star-forming galaxies. Although galaxies well below the MS tend to be undetected in the Arecibo and IRAM observations, reliable mean atomic and molecular gas fractions can be obtained through a spectral stacking technique. We find that the position of galaxies in the SFR-M* plane can be explained mostly by their global cold gas reservoirs as observed in the H I line, with in addition systematic variations in the molecular-to-atomic ratio and star formation efficiency. When looking at galaxies within ±0.4 dex of the MS, we find that as stellar mass increases, both atomic and molecular gas mass fractions decrease, stellar bulges become more prominent, and the mean stellar ages increase. Both star formation efficiency and molecular-to-atomic ratios vary little for massive MS galaxies, indicating that the flattening of the MS is due to the global decrease of the cold gas reservoirs of galaxies rather than to bottlenecks in the process of converting cold atomic gas to stars.

  14. Molecular and atomic gas in the Local Group galaxy M 33

    NARCIS (Netherlands)

    Gratier, P.; Braine, J.; Rodriguez-Fernandez, N. J.; Schuster, K. F.; Kramer, C.; Xilouris, E. M.; Tabatabaei, F. S.; Henkel, C.; Corbelli, E.; Israel, F.; van der Werf, P. P.; Calzetti, D.; Garcia-Burillo, S.; Sievers, A.; Combes, F.; Wiklind, T.; Brouillet, N.; Herpin, F.; Bontemps, S.; Aalto, S.; Koribalski, B.; van der Tak, F.; Wiedner, M. C.; Röllig, M.; Mookerjea, B.

    2010-01-01

    We present high-resolution large-scale observations of the molecular and atomic gas in the Local Group galaxy M 33. The observations were carried out using the HEterodyne Receiver Array (HERA) at the 30 m IRAM telescope in the CO(2-1) line, achieving a resolution of 12” × 2.6 km s-1, enabling indivi

  15. Molecular and atomic gas in the Local Group galaxy M 33

    NARCIS (Netherlands)

    Gratier, P.; Braine, J.; Rodriguez-Fernandez, N. J.; Schuster, K. F.; Kramer, C.; Xilouris, E. M.; Tabatabaei, F. S.; Henkel, C.; Corbelli, E.; Israel, F.; Calzetti, D.; Garcia-Burillo, S.; Sievers, A.; Combes, F.; Wiklind, T.; Brouillet, N.; Herpin, F.; Bontemps, S.; Aalto, S.; Koribalski, B.; van der Tak, F.; Wiedner, M. C.; Roellig, M.; Mookerjea, B.; van der Werf, Paul P.

    2010-01-01

    We present high-resolution large-scale observations of the molecular and atomic gas in the Local Group galaxy M 33. The observations were carried out using the HEterodyne Receiver Array (HERA) at the 30 m IRAM telescope in the CO(2-1) line, achieving a resolution of 12 '' x 2.6 km s(-1), enabling in

  16. Flash Atomization: A New Concept to Control Combustion Instability in Water-Injected Gas Turbines

    Directory of Open Access Journals (Sweden)

    Vishwas Iyengar

    2012-01-01

    Full Text Available The objective of this work is to explore methods to reduce combustor rumble in a water-injected gas turbine. Attempts to use water injection as a means to reduce NOX emissions in gas turbines have been largely unsuccessful because of increased combustion instability levels. This pulsation causes chronic fretting, wear, and fatigue that damages combustor components. Of greater concern is that liberated fragments could cause extensive damage to the turbine section. Combustion instability can be tied to the insufficient atomization of injected water; large water droplets evaporate non-uniformly that lead to energy absorption in chaotic pulses. Added pulsation is amplified by the combustion process and acoustic resonance. Effervescent atomization, where gas bubbles are injected, is beneficial by producing finely atomized droplets; the gas bubbles burst as they exit the nozzles creating additional energy to disperse the liquid. A new concept for effervescent atomization dubbed “flash atomization” is presented where water is heated to just below its boiling point in the supply line so that some of it will flash to steam as it leaves the nozzle. An advantage of flash atomization is that available heat energy can be used rather than mechanical energy to compress injection gas for conventional effervescent atomization.

  17. HOT GAS LINES IN T TAURI STARS

    Energy Technology Data Exchange (ETDEWEB)

    Ardila, David R. [NASA Herschel Science Center, California Institute of Technology, MC 100-22, Pasadena, CA 91125 (United States); Herczeg, Gregory J. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Gregory, Scott G.; Hillenbrand, Lynne A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Ingleby, Laura; Bergin, Edwin; Bethell, Thomas; Calvet, Nuria [Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States); France, Kevin; Brown, Alexander [Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309-0389 (United States); Edwards, Suzan [Department of Astronomy, Smith College, Northampton, MA 01063 (United States); Johns-Krull, Christopher [Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States); Linsky, Jeffrey L. [JILA, University of Colorado and NIST, 440 UCB Boulder, CO 80309-0440 (United States); Yang, Hao [Institute for Astrophysics, Central China Normal University, Wuhan 430079 (China); Valenti, Jeff A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Abgrall, Herve [LUTH and UMR 8102 du CNRS, Observatoire de Paris, Section de Meudon, Place J. Janssen, F-92195 Meudon (France); Alexander, Richard D. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Brown, Joanna M.; Espaillat, Catherine [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78, Cambridge, MA 02138 (United States); Hussain, Gaitee, E-mail: ardila@ipac.caltech.edu [ESO, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Muenchen (Germany); and others

    2013-07-01

    For Classical T Tauri Stars (CTTSs), the resonance doublets of N V, Si IV, and C IV, as well as the He II 1640 A line, trace hot gas flows and act as diagnostics of the accretion process. In this paper we assemble a large high-resolution, high-sensitivity data set of these lines in CTTSs and Weak T Tauri Stars (WTTSs). The sample comprises 35 stars: 1 Herbig Ae star, 28 CTTSs, and 6 WTTSs. We find that the C IV, Si IV, and N V lines in CTTSs all have similar shapes. We decompose the C IV and He II lines into broad and narrow Gaussian components (BC and NC). The most common (50%) C IV line morphology in CTTSs is that of a low-velocity NC together with a redshifted BC. For CTTSs, a strong BC is the result of the accretion process. The contribution fraction of the NC to the C IV line flux in CTTSs increases with accretion rate, from {approx}20% to up to {approx}80%. The velocity centroids of the BCs and NCs are such that V{sub BC} {approx}> 4 V{sub NC}, consistent with the predictions of the accretion shock model, in at most 12 out of 22 CTTSs. We do not find evidence of the post-shock becoming buried in the stellar photosphere due to the pressure of the accretion flow. The He II CTTSs lines are generally symmetric and narrow, with FWHM and redshifts comparable to those of WTTSs. They are less redshifted than the CTTSs C IV lines, by {approx}10 km s{sup -1}. The amount of flux in the BC of the He II line is small compared to that of the C IV line, and we show that this is consistent with models of the pre-shock column emission. Overall, the observations are consistent with the presence of multiple accretion columns with different densities or with accretion models that predict a slow-moving, low-density region in the periphery of the accretion column. For HN Tau A and RW Aur A, most of the C IV line is blueshifted suggesting that the C IV emission is produced by shocks within outflow jets. In our sample, the Herbig Ae star DX Cha is the only object for which we find a

  18. Refined potentials for rare gas atom adsorption on rare gas and alkali-halide surfaces

    Science.gov (United States)

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

    1985-01-01

    The utilization of models of interatomic potential for physical interaction to estimate the long range attractive potential for rare gases and ions is discussed. The long range attractive force is calculated in terms of the atomic dispersion properties. A data base of atomic dispersion parameters for rare gas atoms, alkali ion, and halogen ions is applied to the study of the repulsive core; the procedure for evaluating the repulsive core of ion interactions is described. The interaction of rare gas atoms on ideal rare gas solid and alkali-halide surfaces is analyzed; zero coverage absorption potentials are derived.

  19. Gas Atomization of Aluminium Melts: Comparison of Analytical Models

    Directory of Open Access Journals (Sweden)

    Georgios Antipas

    2012-06-01

    Full Text Available A number of analytical models predicting the size distribution of particles during atomization of Al-based alloys by N2, He and Ar gases were compared. Simulations of liquid break up in a close coupled atomizer revealed that the finer particles are located near the center of the spray cone. Increasing gas injection pressures led to an overall reduction of particle diameters and caused a migration of the larger powder particles towards the outer boundary of the flow. At sufficiently high gas pressures the spray became monodisperse. The models also indicated that there is a minimum achievable mean diameter for any melt/gas system.

  20. High-speed cinematography of gas-metal atomization

    Energy Technology Data Exchange (ETDEWEB)

    Ting, Jason [ALCOA Specialty Metals Division, 100 Technical Drive, Alcoa Center, PA 15069 (United States)]. E-mail: jason.ting@alcoa.com; Connor, Jeffery [Material Science Engineering Department, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Ridder, Stephen [Metallurgical Processing Group, NIST, 100 Bureau Dr. Stop 8556, Gaithersburg, MD 20899 (United States)

    2005-01-15

    A high-speed cinematographic footage of a 304L stainless steel gas atomization, recorded at the National Institute of Standard and Technology (NIST), was analyzed using a discrete Fourier transform (DFT) algorithm. The analysis showed the gas atomization process possesses two prominent frequency ranges of melt oscillation (pulsation). A low-frequency oscillation in the melt flow occurring between 5.41 and 123 Hz, with a dominant frequency at 9.93 Hz, was seen in the recirculation zone adjacent to the melt orifice. A high-frequency melt oscillation range was observed above 123 Hz, and was more prominent one melt-tip-diameter downstream in the melt atomization image than upstream near the melt tip. This high-frequency range may reflect the melt atomization frequency used to produce finely atomized powder. This range also included a prominent high frequency at 1273 Hz, which dominated in the image further away downstream from the melt tip. This discrete high-frequency oscillation is most probably caused by the aeroacoustic ''screech'' phenomenon, intrasound (<20 kHz), a result of the atomizing gas jets undergoing flow resonance. It is hypothesized that this discrete intrinsic aeroacoustic tone may enhance melt breakup in the atomization process with evidence of this fact in the melt images.

  1. The Vienna atomic line data base - a status report

    Energy Technology Data Exchange (ETDEWEB)

    Ryabchikova, T.A. [Rossijskaya Akademiya Nauk, Moscow (Russian Federation). Inst. Astronomii; Piskunov, N.E.; Stempels, H.C. [Uppsala Astronomiska Observatoriet (Sweden); Kupka, F.; Weiss, W.W. [Vienna Univ. (Austria). Inst. fuer Astronomie

    1999-07-01

    Atomic transition parameters are of fundamental importance for many aspects of astrophysical research. But this information is spread over an enormous variety of publications in the fields of, e.g., applied and atomic physics, chemistry, and astronomy. Moreover, they differ in parameters listed and physical units used, as well as in their relative and absolute accuracy. This unfortunate situation led us to create a set of both critically evaluated and more homogeneous lists of astrophysically important atomic transition parameters and of supporting extraction software. This new data base is called the ''Vienna atomic line data base'' (VALD) and contains about 600000 entries for spectral lines with measured energy levels. VALD includes tools for extracting data and references which are particularly suitable for astrophysical applications such as spectrum synthesis and model atmosphere calculations. They are described in papers by Piskunov et al. (1995) and Kupka et al. (1999). We describe in this paper the structure of VALD, present a summary of all available data sets, explain our ranking procedure, in particular for the case of recent data on Fe I and Fe II, and comment briefly on the specific retrieval tools. The electronic-mail interface VALD-EMS allows remote access to VALD and is now extended by the WWW interfaces: http://www.astro.univie.ac.at/{proportional_to}vald http://www.astro.uu.se/{proportional_to}vald (orig.)

  2. The Vienna Atomic Line Data Base - a Status Report

    Science.gov (United States)

    Ryabchikova, T. A.; Piskunov, N. E.; Stempels, H. C.; Kupka, F.; Weiss, W. W.

    Atomic transition parameters are of fundamental importance for many aspects of astrophysical research. But this information is spread over an enormous variety of publications in the fields of, e.g., applied and atomic physics, chemistry, and astronomy. Moreover, they differ in parameters listed and physical units used, as well as in their relative and absolute accuracy. This unfortunate situation led us to create a set of both critically evaluated and more homogeneous lists of astrophysically important atomic transition parameters and of supporting extraction software. This new data base is called the “Vienna Atomic Line Data Base” (VALD) and contains about 600000 entries for spectral lines with measured energy levels. VALD includes tools for extracting data and references which are particularly suitable for astrophysical applications such as spectrum synthesis and model atmosphere calculations. They are described in papers by Piskunov et al. (1995) and Kupka et al. (1999). We describe in this paper the structure of VALD, present a summary of all available data sets, explain our ranking procedure, in particular for the case of recent data on Fe I and Fe II, and comment briefly on the specific retrieval tools. The electronic-mail interface VALD-EMS allows remote access to VALD and is now extended by the WWW interfaces: http://www.astro.univie.ac.at/˜vald http://www.astro.uu.se/˜vald

  3. Intense Atomic and Molecular Beams via Neon Buffer Gas Cooling

    CERN Document Server

    Patterson, David; Doyle, John M

    2008-01-01

    We realize a continuous guided beam of cold deuterated ammonia with a flux of 3e11 ND3 molecules/s and a continuous free-space beam of cold potassium with a flux of 1e16 K atoms/s. A novel feature of the buffer gas source used to produce these beams is cold neon, which, due to intermediate Knudsen number beam dynamics, produces a forward velocity and low-energy tail that is comparable to much colder helium-based sources. We expect this source to be trivially generalizable to a very wide range of atomic and molecular species with significant vapor pressure below 1000 K. This source has properties that make it a good starting point for laser cooling of molecules or atoms, cold collision studies, trapping, or nonlinear optics in buffer-gas-cooled atomic or molecular gases.

  4. Determining protoplanetary disk gas masses from CO isotopologues line observations

    Science.gov (United States)

    Miotello, A.; van Dishoeck, E. F.; Kama, M.; Bruderer, S.

    2016-10-01

    Context. Despite intensive studies of protoplanetary disks, there is still no reliable way to determine their total (gast+dust) mass and their surface density distribution, quantities that are crucial for describing both the structure and the evolution of disks up to the formation of planets. Aims: The goal of this work is to use less-abundant CO isotopologues, such as 13CO, C18O and C17O, detection of which is routine for ALMA, to infer the gas mass of disks. Isotope-selective effects need to be taken into account in the analysis, because they can significantly modify CO isotopologues' line intensities. Methods: CO isotope-selective photodissociation has been implemented in the physical-chemical code DALI (Dust And LInes) and more than 800 disk models have been run for a range of disk and stellar parameters. Dust and gas temperature structures have been computed self-consistently, together with a chemical calculation of the main atomic and molecular species. Both disk structure and stellar parameters have been investigated by varying the parameters in the grid of models. Total fluxes have been ray-traced for different CO isotopologues and for various low J-transitions for different inclinations. Results: A combination of 13CO and C18O total intensities allows inference of the total disk mass, although with non-negligible uncertainties. These can be overcome by employing spatially resolved observations, that is the disk's radial extent and inclination. Comparison with parametric models shows differences at the level of a factor of a few, especially for extremely low and high disk masses. Finally, total line intensities for different CO isotopologue and for various low-J transitions are provided and are fitted to simple formulae. The effects of a lower gas-phase carbon abundance and different gas-to-dust ratios are investigated as well, and comparison with other tracers is made. Conclusions: Disk masses can be determined within a factor of a few by comparing CO

  5. Observation of individual tracer atoms in an ultracold dilute gas

    CERN Document Server

    Hohmann, Michael; Lausch, Tobias; Mayer, Daniel; Schmidt, Felix; Lutz, Eric; Widera, Artur

    2016-01-01

    Understanding the motion of a tracer particle in a rarefied gas is of fundamental and practical importance. We report the experimental investigation of individual Cs atoms impinging on a dilute cloud of ultracold Rb atoms with variable density. We study the nonequilibrium relaxation of the initial nonthermal state and detect the effect of single collisions which has eluded observation so far. We show that after few collisions, the measured spatial distribution of the light tracer atoms is correctly described by a generalized Langevin equation with a velocity-dependent friction coefficient, over a large range of Knudsen numbers.

  6. A Novel Method of Atomization with Potential Gas Turbine Applications

    Directory of Open Access Journals (Sweden)

    Arthur H. Lefebvre

    1988-10-01

    Full Text Available In conventional airblast or air-assist nozzles the bulk liquid to be atomized is first transformed into a jet or sheet before being exposed to the atomizing air. In the method of atomization dcscribed in this paper, the air is introduced into the bulk liquid at somc point upstream of the nozzle discharge orifice. This injectcd air forms bubbles which'explode' downstream of the injection orifice thereby shattering the liquid into small drops.Experiments carrried out on this atomizer, using water as the working fluid and nitrogen as the driving gas, show that good atomization can be achieved using only small amounts of atomizing gas at injection pressures as low as 173 kPa (25psi. It is found that atomization quality is largely independent of the size of the nozzle discharge orifice. Thus the system appears to have good potential for applications where small holes and passages cannot be employed due to the risk of blockage by contaminants in the fuel.

  7. On-line laser spectroscopy with thermal atomic beams

    CERN Document Server

    Thibault, C; De Saint-Simon, M; Duong, H T; Guimbal, P; Huber, G; Jacquinot, P; Juncar, P; Klapisch, Robert; Liberman, S; Pesnelle, A; Pillet, P; Pinard, J; Serre, J M; Touchard, F; Vialle, J L

    1981-01-01

    On-line high resolution laser spectroscopy experiments have been performed in which the light from a CW tunable dye laser interacts at right angles with a thermal atomic beam. /sup 76-98/Rb, /sup 118-145 /Cs and /sup 208-213/Fr have been studied using the ionic beam delivered by the ISOLDE on-line mass separator at CERN while /sup 30-31/Na and /sup 38-47/K have been studied by setting the apparatus directly on-line with the PS 20 GeV proton beam. The principle of the method is briefly explained and some results concerning nuclear structure are given. The hyperfine structure, spins and isotope shifts of the alkali isotopes and isomers are measured. (8 refs).

  8. Boltzmann statistical consideration on the excitation mechanism of iron atomic lines emitted from glow discharge plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Lei; Kashiwakura, Shunsuke; Wagatsuma, Kazuaki, E-mail: wagatuma@imr.tohoku.ac.jp

    2011-11-15

    A Boltzmann plot for many iron atomic lines having excitation energies of 3.3-6.9 eV was investigated in glow discharge plasmas when argon or neon was employed as the plasma gas. The plot did not show a linear relationship over a wide range of the excitation energy, but showed that the emission lines having higher excitation energies largely deviated from a normal Boltzmann distribution whereas those having low excitation energies (3.3-4.3 eV) well followed it. This result would be derived from an overpopulation among the corresponding energy levels. A probable reason for this is that excitations for the high-lying excited levels would be caused predominantly through a Penning-type collision with the metastable atom of argon or neon, followed by recombination with an electron and then stepwise de-excitations which can populate the excited energy levels just below the ionization limit of iron atom. The non-thermal excitation occurred more actively in the argon plasma rather than the neon plasma, because of a difference in the number density between the argon and the neon metastables. The Boltzmann plots yields important information on the reason why lots of Fe I lines assigned to high-lying excited levels can be emitted from glow discharge plasmas. - Highlights: Black-Right-Pointing-Pointer This paper shows the excitation mechanism of Fe I lines from a glow discharge plasma. Black-Right-Pointing-Pointer A Boltzmann distribution is studied among iron lines of various excitation levels. Black-Right-Pointing-Pointer We find an overpopulation of the high-lying energy levels from the normal distribution. Black-Right-Pointing-Pointer It is caused through Penning-type collision of iron atom with argon metastable atom.

  9. Molecular and atomic gas along and across the main sequence of star-forming galaxies

    CERN Document Server

    Saintonge, A; Cortese, L; Genzel, R; Giovanelli, R; Haynes, M P; Janowiecki, S; Kramer, C; Lutz, K A; Schiminovich, D; Tacconi, L J; Wuyts, S; Accurso, G

    2016-01-01

    We use spectra from the ALFALFA, GASS and COLD GASS surveys to quantify variations in the mean atomic and molecular gas mass fractions throughout the SFR-M* plane and along the main sequence (MS) of star-forming galaxies. Although galaxies well below the MS tend to be undetected in the Arecibo and IRAM observations, reliable mean atomic and molecular gas fractions can be obtained through a spectral stacking technique. We find that the position of galaxies in the SFR-M* plane can be explained mostly by their global cold gas reservoirs as observed in the HI line, with in addition systematic variations in the molecular-to-atomic ratio and star formation efficiency. When looking at galaxies within +/-0.4 dex of the MS, we find that as stellar mass increases, both atomic and molecular gas mass fractions decrease, stellar bulges become more prominent, and the mean stellar ages increase. Both star formation efficiency and molecular-to-atomic ratios vary little for massive main sequence galaxies, indicating that the ...

  10. The news about Vienna Atomic Line Data Base

    Science.gov (United States)

    Piskunov, N.; Ryabchikova, T. A.; Weiss, W. W.

    We describe the main changes in the ``Vienna Atomic Line Data Base'' (VALD, Piskunov et al., 1995 and Piskunov, 1996) that have been made since the first release in 1994. The original VALD lists have been complemented with critically evaluated data obtained from experimental measurements and theoretical calculations which are necessary for computing state-of-the-art line opacities in stellar atmospheres, as well as for spectral synthesis for high precision studies (e.g. abundances, radial velocities etc.). In this paper we present new and improved data sets for chemical elements that have already been included in VALD, for new elements and for additional higher ionized species. Software modifications allow remote users of VALD to specify individual extraction parameters as an alternative to the default settings of the VALD team and to have direct control over the quality ranking of line data. The new World--Wide--Web interface provides easy access to all new features. The support for the mirror site permitted opening of two additional VALD servers at Hoddard Space Flight Center (USA) and at Uppsala Astronomical Observatory (Sweden). For proper crediting of all authors of atomic data, VALD now includes a compilation of all publications used to any replies.

  11. Asymmetry of the natural line profile for the hydrogen atom.

    Science.gov (United States)

    Labzowsky, L N; Solovyev, D A; Plunien, G; Soff, G

    2001-10-01

    The asymmetry of the natural line profile for transitions in hydrogenlike atoms is evaluated within a QED framework. For the Lyman- alpha 1s-2p absorption transition in neutral hydrogen this asymmetry results in an additional energy shift of 2.929 856 Hz. For the 2s(1/2)-2p(3/2) transition it amounts to -1.512 674 Hz. As a new feature this correction turns out to be process dependent. The quoted numbers refer to the Compton-scattering process.

  12. Flame-in-gas-shield and miniature diffusion flame hydride atomizers for atomic fluorescence spectrometry: optimization and comparison

    OpenAIRE

    Marschner, K; Musil, S. (Stanislav); Dědina, J. (Jiří)

    2015-01-01

    A detailed optimization of relevant experimental parameters of two hydride atomizers for atomic fluorescence spectrometry: flame-in-gas-shield atomizer with a two-channel shielding unit and a standard atomizer for atomic fluorescence spectrometry, miniature diffusion flame, was performed. Arsine, generated by the reaction with NaBH4 in a flow injection arrangement, was chosen as the model hydride. Analytical characteristics of both the atomizers (sensitivity, noise, limits of detection) were ...

  13. Angular Momentum Regulates Atomic Gas Fractions of Galactic Disks

    CERN Document Server

    Obreschkow, Danail; Kilborn, Virginia; Lutz, Katharina

    2016-01-01

    We show that the mass fraction f_atm = 1.35*MHI/M of neutral atomic gas (HI and He) in isolated local disk galaxies of baryonic mass M is well described by a straightforward stability model for flat exponential disks. In the outer disk parts, where gas at the characteristic dispersion of the Warm Neutral Medium is stable in the sense of Toomre (1964), the disk consists of neutral atomic gas; conversely the inner part where this medium would be Toomre-unstable, is dominated by stars and molecules. Within this model, f_atm only depends on a global stability parameter q=j*sigma/(GM), where j is the baryonic specific angular momentum of the disk and sigma the velocity dispersion of the atomic gas. The analytically derived first-order solution f_atm = min{1,2.5q^1.12} provides a good fit to all plausible rotation curves. This model, with no free parameters, agrees remarkably well (+-0.2 dex) with measurements of f_atm in isolated local disk galaxies, even with galaxies that are extremely HI-rich or HI-poor for the...

  14. Rapid formation of molecular clouds from turbulent atomic gas

    Science.gov (United States)

    Glover, S. C. O.; Mac Low, M.-M.

    The characteristic lifetimes of molecular clouds remain uncertain and a topic of frequent debate, with arguments having recently been advanced both in support of short-lived clouds, with lifetimes of a few Myr or less (see e.g. Elmegreen 2000; Hartmann et al. 2001) and in support of much longer-lived clouds, with lifetimes of the order of 10 Myr or more (see e.g. Tassis & Mouschovias, 2004; Goldsmith & Li, 2005). An argument that has previously been advanced in favour of longer lived clouds is the apparent difficulty involved in converting sufficient atomic hydrogen to molecular hydrogen within the short timescale required by the rapid cloud formation scenario. However, previous estimates of the time required for this conversion to occur have not taken into account the effects of the supersonic turbulence which is inferred to be present in the atomic gas. In this contribution, we present results from a set of high resolution three-dimensional simulations of turbulence in gravitationally unstable atomic gas. These simulations were performed using a modified version of the ZEUS-MP hydrodynamical code (Norman 2000), and include a detailed treatment of the thermal balance of the gas and of the formation of molecular hydrogen. The effects of photodissociation of H2 by the Galactic UV field are also included, with a simple local approximation used to compute the effects of H2 self-shielding. The results of our simulations demonstrate that H2 formation occurs rapidly in turbulent atomic gas. Starting from purely atomic gas, large quantities of molecular gas can be produced on timescales of less than a Myr, given turbulent velocity dispersions and magnetic field strengths consistent with observations. Moreover, as our simulations underestimate the effectiveness of H2 self-shielding and dust absorption, we can be confident that the molecular fractions which we compute are strong lower limits on the true values. The formation of large quantities of molecular gas on the

  15. Ultrasonic gas alloy atomization under near-zero aspiration pressure

    Science.gov (United States)

    Yan, Pengfei; Wang, Deping; Yan, Biao

    2015-04-01

    In this paper, ultrasonic gas atomization (USGA) of Zn-Al under near-zero aspiration pressure was discussed. The protrusion length of delivery tube was modified to adjust the aspiration pressure. Under near-zero aspiration pressure, melt filming was observed by camera and more fine powders were produced. While under larger subambient aspiration pressure, melt filming was unavailable, corresponding to less fine powders. The results suggest that the position of the wake near the delivery tube can be optimized under near-zero aspiration. Less protrusion of delivery tube reduces the energy loss in gas flow deflection. Both facilitate to produce finer powders.

  16. Hot Gas Lines in T Tauri Stars

    CERN Document Server

    Ardila, David R; Gregory, Scott G; Ingleby, Laura; France, Kevin; Brown, Alexander; Edwards, Suzan; Johns-Krull, Christopher; Linsky, Jeffrey L; Yang, Hao; Valenti, Jeff A; Abgrall, Hervé; Alexander, Richard D; Bergin, Edwin; Bethell, Thomas; Brown, Joanna M; Calvet, Nuria; Espaillat, Catherine; Hillenbrand, Lynne A; Hussain, Gaitee; Roueff, Evelyne; Schindhelm, Eric R; Walter, Frederick M

    2013-01-01

    For Classical T Tauri Stars (CTTSs), the resonance lines of N V, Si IV, and C IV, as well as the He II 1640 A line, act as diagnostics of the accretion process. Here we assemble a large high-resolution dataset of these lines in CTTSs and Weak T Tauri Stars (WTTSs). We present data for 35 stars: one Herbig Ae star, 28 CTTSs, and 6 WTTSs. We decompose the C IV and He II lines into broad and narrow Gaussian components (BC & NC). The most common (50 %) C IV line morphology in CTTSs is that of a low-velocity NC together with a redshifted BC. The velocity centroids of the BCs and NCs are such that V_BC > 4 * V_NC, consistent with the predictions of the accretion shock model, in at most 12 out of 22 CTTSs. We do not find evidence of the post-shock becoming buried in the stellar photosphere due to the pressure of the accretion flow. The He II CTTSs lines are generally symmetric and narrow, less redshifted than the CTTSs C IV lines, by ~10 km/sec. The flux in the BC of the He II line is small compared to that of t...

  17. Flame-in-gas-shield and miniature diffusion flame hydride atomizers for atomic fluorescence spectrometry: optimization and comparison

    Energy Technology Data Exchange (ETDEWEB)

    Marschner, Karel, E-mail: karel.marschner@biomed.cas.cz [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Charles University in Prague, Faculty of Science, Department of Analytical Chemistry, Albertov 8, 128 43 Prague (Czech Republic); Musil, Stanislav; Dědina, Jiří [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic)

    2015-07-01

    A detailed optimization of relevant experimental parameters of two hydride atomizers for atomic fluorescence spectrometry: flame-in-gas-shield atomizer with a two-channel shielding unit and a standard atomizer for atomic fluorescence spectrometry, miniature diffusion flame, was performed. Arsine, generated by the reaction with NaBH{sub 4} in a flow injection arrangement, was chosen as the model hydride. Analytical characteristics of both the atomizers (sensitivity, noise, limits of detection) were compared. Under optimum conditions sensitivity obtained with flame-in-gas-shield atomizer was approximately twice higher than with miniature diffusion flame. The additional advantage of flame-in-gas-shield atomizer is significantly lower flame emission resulting in a better signal to noise ratio. The resulting arsenic limits of detection for miniature diffusion flame and flame-in-gas-shield atomizer were 3.8 ng l{sup −1} and 1.0 ng l{sup −1}, respectively. - Highlights: • We optimized and compared two hydride atomizers for atomic fluorescence spectrometry. • Miniature diffusion flame and flame-in-gas-shield atomizer were optimized. • The limit of detection for arsenic was 1.0 ng l{sup −1}.

  18. Atomization mechanisms and gas phase reactions in graphite furnace atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Frech, W.; Lindberg, A.O.; Lundberg, E.; Cedergren, A.

    1986-04-01

    The amounts of carbon monoxide as well as the total amounts of hydrocarbons generated in different types of graphite tubes were investigated under various experimental conditions. Depending on whether or not a matrix like 50 ..mu..g of sodium nitrate was added the amount of carbon monoxide formed during atomization at 1,700 K in a pyrocoated tube was in the range 60 to 600 nmoles when using a thermal pretreatment temperature of 1,200 K. The corresponding values for an uncoated tube were 250 to 1,300 nmoles. The effect of carbon monoxide on the atomization behaviour of silver, bismuth, chromium, copper and lead was investigated experimentally and the results were evaluated by means of thermodynamically based models. In accordance with theoretical predications, only lead, bismuth and chromium, which are assumed to be atomized by oxide decomposition, showed substantial shifts in their appearance temperatures in different gas mixtures, and changes in activation energies.

  19. Atomic Data and Spectral Line Intensities for fe XI

    Science.gov (United States)

    Bhatia, A. K.; Doschek, G. A.; Eissner, W.

    2002-11-01

    Electron impact collision strengths and spontaneous radiative decay rates are calculated for Fe XI. The data pertain to the 96 levels of the configurations 3s23p4, 3s3p5, 3s23p33d, 3p6, 3s23p34s, and 3s23p34d. Collision strengths are calculated at 10 incident electron energies: 1.0, 3.4, 6.0, 12.0, 15.0, 30.0, 45.0, 60.0, 75.0, and 90.0 Ry. These atomic data are generated to support the interpretation of spectra of astrophysical objects, which frequently contain emission lines from Fe XI and similar ions. This work supplements previous work published on Fe XI by extending the calculation of collision strengths and radiative decay rates to levels within n=4 configurations. Relative spectral line intensities are calculated for all astrophysically important transitions. These are obtained by computing the excitation rate coefficients (cm3 s-1), i.e., the collision strengths integrated over a Maxwellian electron distribution, and then solving the equations of detailed balance for the populations of the 96 energy levels, assuming a collisional excitation model and an electron temperature of 1.3×106 K. This temperature is typical for Fe XI when formed at equilibrium by collisional ionization and recombination. Using the excitation rate coefficients and the radiative decay rates, level populations are computed for several electron densities. The calculation of line intensities and level populations includes proton excitation because hydrogen is the most abundant element in astrophysical plasmas relevant to Fe XI emission.

  20. The Gas Flow from the Gas Attenuator to the Beam Line

    Energy Technology Data Exchange (ETDEWEB)

    Ryutov, D.D.

    2010-12-03

    The gas leak from the gas attenuator to the main beam line of the Linac Coherent Light Source has been evaluated, with the effect of the Knudsen molecular beam included. It has been found that the gas leak from the gas attenuator of the present design, with nitrogen as a working gas, does not exceed 10{sup -5} torr x l/s even at the highest pressure in the main attenuation cell (20 torr).

  1. Bolivia-Brazil gas line route detailed

    Energy Technology Data Exchange (ETDEWEB)

    1992-05-11

    This paper reports that state oil companies of Brazil and Bolivia have signed an agreement outlining the route for a 2,270 km pipeline system to deliver natural gas from Bolivian fields to Southeast Brazil. The two sides currently are negotiating details about construction costs as well as contract volumes and prices. Capacity is projected at 283-565 MMcfd. No official details are available, but Roberto Y. Hukai, a director of the Sao Paulo engineering company Jaako Poyry/Technoplan, estimates transportation cost of the Bolivian gas at 90 cents/MMBTU. That would be competitive with the price of gas delivered to the Sao Paulo gas utility Comgas, he the. Brazil's Petroleos Brasileiro SA estimates construction of the pipeline on the Brazilian side alone with cost $1.2-1.4 billion. Bolivia's Yacimientos Petroliferos Fiscales Bolivianos (YPFB) is negotiating with private domestic and foreign investors for construction of the Bolivian portion of the project.

  2. Computer monitors natural-gas-liquids line

    Energy Technology Data Exchange (ETDEWEB)

    Muldoon, J.F.; Wilson, W.O.

    1974-12-09

    A new computer-based system continuously monitors composition, flow, and specific gravity of natural-gas liquids flowing in a pipeline. Compositional analysis is performed automatically, under computer control, by a process gas chromatograph. The chromatograph is tailored for hydrocarbon analysis and will separate these compounds into individual components: nitrogen, carbon dioxide, methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, 1-hexane, 2-hexane, 3-hexane, 4-hexane, and heptanes-and-heavier. At the completion of the analysis, the compositional totals, barrels, and pounds, are updated based on flow and average specific gravity. Reports generated include a compositional report, a subtotal ticket report, and a ticket report. The new system, designated Pro-PACE-100, has been successfully installed in several pipeline applications, including one for Mid-America Pipeline Co. in New Mexico.

  3. Observations of absorption lines from highly ionized atoms. [of interstellar medium

    Science.gov (United States)

    Jenkins, Edward B.

    1987-01-01

    In the ultraviolet spectra of hot stars, absorption lines can be seen from highly ionized species in the interstellar medium. Observations of these features which have been very influential in revising the perception of the medium's various physical states, are discussed. The pervasiveness of O 6 absorption lines, coupled with complementary observations of a diffuse background in soft X-rays and EUV radiation, shows that there is an extensive network of low density gas (n approx. few x 0.001/cu cm) existing at coronal temperatures log T = 5.3 or 6.3. Shocks created by supernova explosions or mass loss from early-type stars can propagate freely through space and eventually transfer a large amount of energy to the medium. To create the coronal temperatures, the shocks must have velocities in excess of 150 km/sec; shocks at somewhat lower velocity (v = 100 km/sec) can be directly observed in the lines of Si3. Observations of other lines in the ultraviolet, such as Si 4V and C 5, may highlight the widespread presence of energetic UV radiation from very hot, dwarf stars. More advanced techniques in visible and X-ray astronomical spectroscopy may open up for inspection selected lines from atoms in much higher stages of ionization.

  4. Gas atomization of cobalt ferrite-phosphate melts

    Science.gov (United States)

    De Guire, Mark R.; O'Handley, R. C.; Kalonji, G.

    1989-01-01

    XRD, Moessbauer spectroscopy, and EDXS have been used to characterize a rapidly-solidified (Co,Fe)3O4 spinel generated in a cobalt-iron-phosphate glass matrix by gas atomization of melts. Of the two compositions tested, that containing 20 mol pct P2O5 exhibited randomly-oriented ferrite crystallization whose growth appears to have been diffusion-controlled. Unlike the ferrite, in which the iron has both tetrahedral and octahedral coordination, the iron in the glassy matrix was primarily of distorted-octahedral coordination. Calculations indicate that the cooling rates obtained with oxide melts vary strongly with droplet size, but less strongly with melt temperature.

  5. Atomic Data and Spectral Line Intensities for Ni XV

    Science.gov (United States)

    Landi, E.; Bhatia, A. K.

    2011-01-01

    Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for Ni XV.Weinclude in the calculations the 9 lowest configurations, corresponding to 126 fine structure levels: 3s23p2, 3s3p3, 3s23p3d, 3p4, 3s3p23d, and 3s2 3p4l with l =, s, p, d, f. Collision strengths are calculated at five incident energies for all transitions: 7.8, 18.5, 33.5, 53.5, and 80.2 Ry above the threshold of each transition. An additional energy, very close to the transition threshold, has been added, whose value is between 0.004 and 0.28 Ry depending on the levels involved. Calculations have been carried out using the Flexible Atomic Code and the distorted-wave approximation. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates calculated in the present work, statistical equilibrium equations for level populations are solved at electron densities covering the 10(exp 8)-10(exp 14)/cu cm range and at an electron temperature of log T(sub e)(K) = 6.4, corresponding to the maximum abundance of Ni XV. Spectral line intensities are calculated, and their diagnostic relevance is discussed. This dataset will be made available in the next version of the CHIANTI database.

  6. Atomic Data and Spectral Line Intensities for Ca IX

    Science.gov (United States)

    Landi, E.; Bhatia, A. K.

    2012-01-01

    Electron impact collision strengths, energy levels, oscillator strengths and spontaneous radiative decay rates are calculated for Ca IX. We include in the calculations the 33 lowest configurations in the n = 3, 4, 5 complexes, corresponding to 283 fine structure levels in the 3l3l ', 3l4l'' and 3l4l''' configurations, where l,l' = s, p, d, l '' = s, p, d, f and l''' = s, p, d, f, g. Collision strengths are calculated at five incident energies for all transitions: 5.8, 13.6, 24.2, 38.6 and 57.9 Ry above the threshold of each transition. An additional energy, very close to the transition threshold, has been added, whose value is between 0.0055 Ry and 0.23 Ry depending on the levels involved. Calculations have been carried out using the Flexible Atomic Code and the distorted wave approximation. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates calculated in the present work, statistical equilibrium equations for level populations are solved at electron densities covering the 10(exp 8)-10(exp 14)/cubic cm range and at an electron temperature of log T(sub e)(K)=5.8, corresponding to the maximum abundance of Ca IX. Spectral line intensities are calculated, and their diagnostic relevance is discussed.

  7. The RESOLVE Survey Atomic Gas Census and Environmental Influences on Galaxy Gas Content

    Science.gov (United States)

    Stark, David; Kannappan, Sheila; Eckert, Kathleen D.; Jonathan, Florez; Hall, Kirsten; Watson, Linda C.; Hoversten, Erik A.; Burchett, Joseph; Guynn, David; Baker, Ashley; Moffett, Amanda J.; Berlind, Andreas A.; Norris, Mark A.; Haynes, Martha P.; Giovanelli, Riccardo; Leroy, Adam K.; Pisano, Daniel J.; Wei, Lisa H.; Gonzalez, Roberto; RESOLVE Team

    2016-01-01

    We present the >93% complete 21cm inventory for the RESOLVE survey, a volume-limited census of ~1500 galaxies spanning diverse environments and probing baryonic masses down to ~109 M⊙. A key strength of the 21cm observational program is its fractional mass limited design, which yields an unbiased inventory of atomic gas mass, with either clean detections or strong upper limits group processes that deplete gas content are active well below the large group/cluster scale. In addition, at fixed halo mass both centrals and satellites in large-scale walls have systematically lower gas fractions than galaxies in filaments or voids, and this trend cannot be fully explained by differing stellar mass distributions within these large-scale environments. Lastly, we show that the abundance of gas-poor (gas-to-stellar mass ratio 1012 M⊙ groups than do more gas-rich but otherwise analogous low halo-mass centrals, suggesting that the gas-poor centrals have lost their gas in flyby interactions with the nearby groups. We discuss how the observed trends may be shaped by a number of physical processes such as gas stripping, starvation, and halo assembly bias. This project has been supported by NSF funding for the RESOLVE survey (AST-0955368), the GBT Student Observing Support program, and a UNC Royster Society of Fellows Dissertation Completion Fellowship.

  8. Gas chromatography coupled with atomic absorption spectrometry — a sensitive instrumentation for mercury speciation

    Science.gov (United States)

    Emteborg, Håkan; Sinemus, Hans-Werner; Radziuk, Bernard; Baxter, Douglas C.; Frech, Wolfgang

    1996-07-01

    New instrumentation for the speciation of mercury is described, and is applied to the analysis of natural water samples. The separation of mercury species is effected using gas chromatography of derivatized mercury species on a widebore capillary column. The solvent is vented using a bypass valve and the separated mercury species are pyrolysed on-line at 800°C for production of mercury atoms. These are then detected by atomic absorption spectrometry (AAS) at the 253.7 and 184.9 nm lines simultaneously in a quartz cuvette. The use of the 184.9 nm line provides a more than five-fold increase in sensitivity compared with the conventional 253.7 nm line and an absolute detection limit of 0.5 pg of mercury. The dynamic range of the combined analytical lines provides a linear response over more than three orders of magnitude. A number of organic compounds not containing mercury are also detected following pyrolysis, especially at the 184.9 nm line. These background species must not co-elute at the retention times for methyl- and inorganic mercury, as otherwise a positive interference would result. By maximizing the chromatographic resolution and minimizing the band broadening in the cuvette by use of a make-up gas, the retention times of interest are freed from co-eluting background peaks. The instrumentation has been applied to the determination of ng l -1 concentrations of methyl- and inorganic mercury in Lake Constance, Germany and within the Lake Constance drinking water supply organization, Bodenseewasserversorgung (BWV). The accuracy for the sum of methyl- and inorganic mercury has been assessed by comparison with an independent method for total mercury based on AAS detection implemented at BWV. Relative detection limits using 1 litre water samples and 15 ml injections of the final hexane extract were 0.03 ng l -1 for methylmercury and 0.4 ng l -1 for inorganic mercury based on the 3j criterion.

  9. Atomic and molecular physics in the gas phase

    Energy Technology Data Exchange (ETDEWEB)

    Toburen, L.H.

    1990-09-01

    The spatial and temporal distributions of energy deposition by high-linear-energy-transfer radiation play an important role in the subsequent chemical and biological processes leading to radiation damage. Because the spatial structures of energy deposition events are of the same dimensions as molecular structures in the mammalian cell, direct measurements of energy deposition distributions appropriate to radiation biology are infeasible. This has led to the development of models of energy transport based on a knowledge of atomic and molecular interactions process that enable one to simulate energy transfer on an atomic scale. Such models require a detailed understanding of the interactions of ions and electrons with biologically relevant material. During the past 20 years there has been a great deal of progress in our understanding of these interactions; much of it coming from studies in the gas phase. These studies provide information on the systematics of interaction cross sections leading to a knowledge of the regions of energy deposition where molecular and phase effects are important and that guide developments in appropriate theory. In this report studies of the doubly differential cross sections, crucial to the development of stochastic energy deposition calculations and track structure simulation, will be reviewed. Areas of understanding are discussed and directions for future work addressed. Particular attention is given to experimental and theoretical findings that have changed the traditional view of secondary electron production for charged particle interactions with atomic and molecular targets.

  10. Coherent optical transients observed in rubidium atomic line filtered Doppler velocimetry experiments

    Energy Technology Data Exchange (ETDEWEB)

    Fajardo, Mario E., E-mail: mario.fajardo@eglin.af.mil; Molek, Christopher D.; Vesely, Annamaria L. [Air Force Research Laboratory, Munitions Directorate, Ordnance Division, Energetic Materials Branch, AFRL/RWME, 2306 Perimeter Road, Eglin AFB, Florida 32542-5910 (United States)

    2015-10-14

    We report the first successful results from our novel Rubidium Atomic Line Filtered (RALF) Doppler velocimetry apparatus, along with unanticipated oscillatory signals due to coherent optical transients generated within pure Rb vapor cells. RALF is a high-velocity and high-acceleration extension of the well-known Doppler Global Velocimetry (DGV) technique for constructing multi-dimensional flow velocity vector maps in aerodynamics experiments [H. Komine, U.S. Patent No. 4,919,536 (24 April 1990)]. RALF exploits the frequency dependence of pressure-broadened Rb atom optical absorptions in a heated Rb/N{sub 2} gas cell to encode the Doppler shift of reflected near-resonant (λ{sub 0} ≈ 780.24 nm) laser light onto the intensity transmitted by the cell. The present RALF apparatus combines fiber optic and free-space components and was built to determine suitable operating conditions and performance parameters for the Rb/N{sub 2} gas cells. It yields single-spot velocities of thin laser-driven-flyer test surfaces and incorporates a simultaneous Photonic Doppler Velocimetry (PDV) channel [Strand et al., Rev. Sci. Instrum. 77, 083108 (2006)] for validation of the RALF results, which we demonstrate here over the v = 0 to 1 km/s range. Both RALF and DGV presume the vapor cells to be simple Beer's Law optical absorbers, so we were quite surprised to observe oscillatory signals in experiments employing low pressure pure Rb vapor cells. We interpret these oscillations as interference between the Doppler shifted reflected light and the Free Induction Decay (FID) coherent optical transient produced within the pure Rb cells at the original laser frequency; this is confirmed by direct comparison of the PDV and FID signals. We attribute the different behaviors of the Rb/N{sub 2} vs. Rb gas cells to efficient dephasing of the atomic/optical coherences by Rb-N{sub 2} collisions. The minimum necessary N{sub 2} buffer gas density ≈0.3 amagat translates into a

  11. Atomic Data and Spectral Line Intensities for Ni XI

    Science.gov (United States)

    Bhatia, A. K.; Landi, E.

    2010-01-01

    Electron impact collision strengths, energy levels, oscillator strengths and spontaneous radiative decay rates are calculated for Ni XI. We include in the calculations the 10 lowest configurations, corresponding to 164 fine structure levels: 3s(sup 2)3p(sup 6), 3s(sup 2)3p(sup 5)3d, 3s(sup 2)3p(sup 4)3d(sup 2), 3s3p(sup 6)3d, 3s(sup 2)3p(sup 5)4l and 3s3p6 4l with l =.s, p, d. Collision strengths are calculated at five incident energies for all transitions: 7.1, 16.8, 30.2, 48.7 and 74.1 Ry above the threshold of each transition. An additional energy, very close to the transition threshold, has been added, whose value is between 0.06 Ry and 0.25 Ry depending on the lower level. Calculations have been carried out using the Flexible Atomic Code and the distorted wave approximation. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates of the present work, combined with Close Coupling collision excitation rate coefficient available in the literature for the lowest 17 levels, statistical equilibrium equations for level populations are solved at electron densities covering the 10(exp 8)-10(exp 14) cu cm range and at an electron temperature of logT(sub c)(K)=6.1, corresponding to the maximum abundance of Ni XI. Spectral line intensities are calculated, and their diagnostic relevance is discussed. This dataset will be made available in the next version of the CHIANTI database.

  12. Off-line test of the KISS gas cell

    Energy Technology Data Exchange (ETDEWEB)

    Hirayama, Yoshikazu, E-mail: yoshikazu.hirayama@kek.jp [Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Ibaraki 305-0801 (Japan); Watanabe, Yutaka; Imai, Nobuaki; Ishiyama, Hironobu; Jeong, Sun-Chan; Miyatake, Hiroari; Oyaizu, Michihiro [Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Ibaraki 305-0801 (Japan); Kim, Yung Hee [Seoul National University, Seoul 151 742 (Korea, Republic of); Mukai, Momo [Tsukuba University, Ibaraki 305 0006 (Japan); Matsuo, Yukari; Sonoda, Tetsu; Wada, Michiharu [Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351 0198 (Japan); Huyse, Mark; Kudryavtsev, Yuri; Van Duppen, Piet [Instituut voor Kern-en Stralingsfysica, KU Leuven, B-3001 Leuven (Belgium)

    2013-12-15

    Highlights: • Construction of the KEK Isotope Separation System (KISS) at RIKEN. • Ionization scheme of an iron. • Measurement of transport time profile in a gas cell. -- Abstract: The KEK Isotope Separation System (KISS) has been constructed at RIKEN to study the β-decay properties of neutron-rich isotopes with neutron numbers around N = 126 for application to astrophysics. A key component of KISS is a gas cell filled with argon gas at a pressure of 50 kPa to stop and collect the unstable nuclei, where the isotopes of interest will be selectively ionized using laser resonance ionization. We have performed off-line tests to study the basic properties of the gas cell and of KISS using nickel and iron filaments placed in the gas cell.

  13. Effect of gas atoms on X-ray optical properties of multilayers

    Institute of Scientific and Technical Information of China (English)

    冯仕猛; 赵海鹰; 范正修; 邵建达; 窦晓鸣

    2003-01-01

    Multilayers always dissolve some gas atoms during sputtering. In this paper, we develop a new method to study the effect of gas atoms on X-ray reflectance of the multilayer. Our theoretical analysis shows that this effect depends not only on the content of gas atom but also on the wavelength and the grazing angle. The shorter the wavelength and the bigger the grazing angle, the stronger this effect of gas atoms. We fabricated Mo/Si multilayers under various sputtering pressures and measured their small angle X-ray diffraction spectra. The measured results coincide with those calculated by our method.

  14. c2d Spitzer IRS spectra of embedded low-mass young stars : gas-phase emission lines

    NARCIS (Netherlands)

    Lahuis, F.; van Dishoeck, E. F.; Jorgensen, J. K.; Blake, G. A.; Evans, N. J.

    2010-01-01

    Context. A survey of mid-infrared gas-phase emission lines of H(2), H(2)O and various atoms toward a sample of 43 embedded low-mass young stars in nearby star-forming regions is presented. The sources are selected from the Spitzer "Cores to Disks" (c2d) legacy program. Aims. The environment of embed

  15. Estimated Buried Power and Gas Lines at Little Bighorn Battlefield National Monument, Montana

    Data.gov (United States)

    National Park Service, Department of the Interior — The gas and power lines were compiled from utility lines collected with GPS equipment in the summer of 2003 and then merged with older gas and power line data...

  16. Production of Hyperpolarized 129Xe Gas Without Nitrogen by Optical Pumping at 133Cs D2 line in Flow System

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xin; SUN Xian-Ping; LUO Jun; ZENG Xi-Zhi; LIU Mai-Li; ZHAN Ming-Sheng

    2004-01-01

    @@ We report production of hyperpolarized 129Xe gas via spin-exchange with optically pumped Cs atoms at the D2 line, achieved at low magnetic field in a flow system and in the absence of nitrogen gas. The nuclear spin polarization of hyperpolarized 129Xe gas is enhanced by a factor of 10000 compared to that without optical pumping under the same condition, which corresponds to polarization of about 2.66%. Due to the high spin polarization, the radiation damping of hyperpolarized 129Xe gas has also been observed in the flow system.

  17. Visualization of Atomization Gas Flow and Melt Break-up Effects in Response to Nozzle Design

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver; Rieken, Joel; Meyer, John; Byrd, David; Heidloff, Andy

    2011-04-01

    Both powder particle size control and efficient use of gas flow energy are highly prized goals for gas atomization of metal and alloy powder to minimize off-size powder inventory (or 'reverb') and excessive gas consumption. Recent progress in the design of close-coupled gas atomization nozzles and the water model simulation of melt feed tubes were coupled with previous results from several types of gas flow characterization methods, e.g., aspiration measurements and gas flow visualization, to make progress toward these goals. Size distribution analysis and high speed video recordings of gas atomization reaction synthesis (GARS) experiments on special ferritic stainless steel alloy powders with an Ar+O{sub 2} gas mixture were performed to investigate the operating mechanisms and possible advantages of several melt flow tube modifications with one specific gas atomization nozzle. In this study, close-coupled gas atomization under closed wake gas flow conditions was demonstrated to produce large yields of ultrafine (dia.<20 {mu}m) powders (up to 32%) with moderate standard deviations (1.62 to 1.99). The increased yield of fine powders is consistent with the dual atomization mechanisms of closed wake gas flow patterns in the near-field of the melt orifice. Enhanced size control by stabilized pre-filming of the melt with a slotted trumpet bell pour tube was not clearly demonstrated in the current experiments, perhaps confounded by the influence of the melt oxidation reaction that occurred simultaneously with the atomization process. For this GARS variation of close-coupled gas atomization, it may be best to utilize the straight cylindrical pour tube and closed wake operation of an atomization nozzle with higher gas mass flow to promote the maximum yields of ultrafine powders that are preferred for the oxide dispersion strengthened alloys made from these powders.

  18. Application of gas-fluid atomization technology in ultrosonic vibration cutting titanium alloy workpiece

    Science.gov (United States)

    Zhou, Zhimin; Zhang, Yuangliang; Li, Xiaoyan; Sun, Baoyuan

    2009-11-01

    To further improve machined surface quality of diamond cutting titanium workpiece and reduce diamond tool wear, it puts forward a kind of machining technology with mixture of carbon dioxide gas, water and vegetable oil atomized mist as cooling media in the paper. The cooling media is sprayed to cutting area through gas-liquid atomizer device to achieve purpose of cooling, lubricating, and protecting diamond tool. Experiments indicate that carbon dioxide gas can touch cutting surface more adequately through using gas-liquid atomization technology, which makes iron atoms of cutting surface cause a chemical reaction directly with carbon in carbon dioxide gas and reduce graphitizing degree of diamond tool. Thus, this technology of using gas-liquid atomization and ultrasonic vibration together for cutting Titanium Alloy is able to improve machined surface quality of workpiece and slow of diamond tool wear.

  19. An ytterbium quantum gas microscope with narrow-line laser cooling

    Science.gov (United States)

    Yamamoto, Ryuta; Kobayashi, Jun; Kato, Kohei; Kuno, Takuma; Sakura, Yuto; Takahashi, Yoshiro

    2016-05-01

    Single-site resolved imaging of alkali metal in a two-dimensional optical lattice (Quantum Gas Microscope, QGM) is realized and enables us to directly observe the in-trap atom distribution and study quantum dynamics with single-site resolution. It is important to extend the applicability of a QGM technique to two-electron atoms such as alkaline-earth metal and ytterbium (Yb) atoms because it opens up many unique possibilities for the quantum simulation and quantum information research. Differently from the first report on single-site resolved imaging of Yb atoms with a long lattice constant 544 nm and a short lifetime of 62 μs without cooling, we successfully realize the QGM of Yb atoms with a short lattice constant 266 nm, in which we achieve a high-resolution imaging with a low temperature of 7.4 μK and a long lifetime of 7 s by narrow-line laser cooling. The high detection fidelity of 87(2) % is achieved in our method. In addition, we are developing a different mode of QGM for Yb atoms.

  20. Long-range interactions of excited He atoms with ground-state noble-gas atoms

    KAUST Repository

    Zhang, J.-Y.

    2013-10-09

    The dispersion coefficients C6, C8, and C10 for long-range interactions of He(n1,3S) and He(n1,3P), 2≤n≤10, with the ground-state noble-gas atoms Ne, Ar, Kr, and Xe are calculated by summing over the reduced matrix elements of multipole transition operators. The large-n expansions for the sums over the He oscillator strength divided by the corresponding transition energy are presented for these series. Using the expansions, the C6 coefficients for the systems involving He(131,3S) and He(131,3P) are calculated and found to be in good agreement with directly calculated values.

  1. The intensity calculation of the gas absorption line by multi-line Voigt fitting

    Institute of Scientific and Technical Information of China (English)

    ZHOU Meng-ran; LI Zhen-bi; ZHONG Ming-yu; HE Gang

    2008-01-01

    Adopted the distribution feedback type (DFB) laser to measure the coal mine gas methane, according to the methane located 1.6 lain nearby 2v3 with a R9 direct ab-sorption spectrum, attraction wire intensity of each line was calculated through the multi-line Voigt fitting. The experimental result indicates that in the obtained four attraction recover of wire, the maximum deviation is 2.7%, and the minimum deviation is 0.02%, other results are all in experimental error scope. This research method may apply in the spectrum survey methane gas density, it has characteristics including high precision, strong selectivity, fast response and so on.

  2. Cosmology with intensity mapping techniques using atomic and molecular lines

    Science.gov (United States)

    Fonseca, José; Silva, Marta B.; Santos, Mário G.; Cooray, Asantha

    2017-01-01

    We present a systematic study of the intensity mapping (IM) technique using updated models for the different emission lines from galaxies. We identify which ones are more promising for cosmological studies of the post-reionization epoch. We consider the emission of Lyα, Hα, Hβ, optical and infrared oxygen lines, nitrogen lines, C II and the CO rotational lines. We show that Lyα, Hα, O II, C II and the lowest rotational CO lines are the best candidates to be used as IM probes. These lines form a complementary set of probes of the galaxies' emission spectra. We then use reasonable experimental setups from current, planned or proposed experiments to assess the detectability of the power spectrum of each emission line. IM of Lyα emission from z = 2 to 3 will be possible in the near future with Hobby-Eberly Telescope Dark Energy Experiment, while far-infrared lines require new dedicated experiments. We also show that the proposed SPHEREx satellite can use O II and Hα IM to study the large-scale distribution of matter in intermediate redshifts of 1-4. We find that submillimetre experiments with bolometers can have similar performances at intermediate redshifts using C II and CO(3-2).

  3. Cosmology with intensity mapping techniques using atomic and molecular lines

    CERN Document Server

    Fonseca, José; Santos, Mário G; Cooray, Asantha

    2016-01-01

    We present a systematic study of the intensity mapping technique using updated models for the different emission lines from galaxies and identify which ones are more promising for cosmological studies of the post reionization epoch. We consider the emission of ${\\rm Ly\\alpha}$, ${\\rm H\\alpha}$, H$\\beta$, optical and infrared oxygen lines, nitrogen lines, CII and the CO rotational lines. We then identify that ${\\rm Ly\\alpha}$, ${\\rm H\\alpha}$, OII, CII and the lowest rotational CO lines are the best candidates to be used as IM probes. These lines form a complementary set of probes of the galaxies emission spectra. We then use reasonable experimental setups from current, planned or proposed experiments to access the detectability of the power spectrum of each emission line. Intensity mapping of ${\\rm Ly\\alpha}$ emission from $z=2$ to 3 will be possible in the near future with HETDEX, while far-infrared lines require new dedicated experiments. We also show that the proposed SPHEREx satellite can use OII and ${\\r...

  4. Absorption Line Signatures of Gas in Mini Dark Matter Halos

    CERN Document Server

    Kepner, J V; Abel, T; Spergel, D N; Kepner, Jeremy; Tripp, Todd; Abel, Tom; Spergel, David

    1999-01-01

    Recent observations and theoretical calculations suggest that some QSO absorption line systems may be due to gas in small dark matter halos with circular velocities on the order of 30 km/s. Additional observational evidence suggests that, in general, many absorption line systems may also be multi-phase in nature. Thus, computing the absorption lines of mini-halos, in addition to providing signatures of small halos, is a natural way to explore multi-phase behavior. The state of gas in mini-halos is strongly affected by the background UV radiation field. To address this issue a code was developed that includes many of the chemical and radiative processes found in CLOUDY and also incorporates spherically symmetric multi-wavelength radiative transfer of an isotropic field, non-equilibrium chemistry, heating, cooling and self-consistent quasi hydro-static equilibrium gas dynamics. With this code detailed simulations were conducted of gas in mini-halos using different types of background spectra. From these simulat...

  5. ACOUSTIC DETECTING AND LOCATING GAS PIPE LINE INFRINGEMENT

    Energy Technology Data Exchange (ETDEWEB)

    John L. Loth; Gary J. Morris; George M. Palmer; Richard Guiler; Patrick Browning

    2004-12-01

    The extensive network of high-pressure natural gas transmission pipelines covering the United States provides an important infrastructure for our energy independence. Early detection of pipeline leaks and infringements by construction equipment, resulting in corrosion fractures, presents an important aspect of our national security policy. The National Energy Technology Laboratory Strategic Center for Natural Gas (SCVG) is and has been funding research on various applicable techniques. The WVU research team has focused on monitoring pipeline background acoustic signals generated and transmitted by gas flowing through the gas inside the pipeline. In case of a pipeline infringement, any mechanical impact on the pipe wall, or escape of high-pressure gas, generates acoustic signals traveling both up and down stream through the gas. Sudden changes in flow noise are detectable with a Portable Acoustic Monitoring Package (PAMP), developed under this contract. It incorporates a pressure compensating microphone and a signal- recording device. Direct access to the gas inside the line is obtained by mounting such a PAMP, with a 1/2 inch NPT connection, to a pipeline pressure port found near most shut-off valves. An FFT of the recorded signal subtracted by that of the background noise recorded one-second earlier appears to sufficiently isolate the infringement signal to allow source interpretation. Using cell phones for data downloading might allow a network of such 1000-psi rated PAMP's to acoustically monitor a pipeline system and be trained by neural network software to positively identify and locate any pipeline infringement.

  6. ACOUSTIC DETECTING AND LOCATING GAS PIPE LINE INFRINGEMENT

    Energy Technology Data Exchange (ETDEWEB)

    John L. Loth; Gary J. Morris; George M. Palmer; Richard Guiler; Patrick Browning

    2004-10-31

    The extensive network of high-pressure natural gas transmission pipelines covering the United States provides an important infrastructure for our energy independence. Early detection of pipeline leaks and infringements by construction equipment, resulting in corrosion fractures, presents an important aspect of our national security policy. The National Energy Technology Laboratory Strategic Center for Natural Gas (SCVG) is and has been funding research on various applicable techniques. The WVU research team has focused on monitoring pipeline background acoustic signals generated and transmitted by gas flowing through the gas inside the pipeline. In case of a pipeline infringement, any mechanical impact on the pipe wall, or escape of high-pressure gas, generates acoustic signals traveling both up and down stream through the gas. Sudden changes in flow noise are detectable with a Portable Acoustic Monitoring Package (PAMP), developed under this contract. It incorporates a pressure compensating microphone and a signal- recording device. Direct access to the gas inside the line is obtained by mounting such a PAMP, with a 1/2 inch NPT connection, to a pipeline pressure port found near most shut-off valves. An FFT of the recorded signal subtracted by that of the background noise recorded one-second earlier appears to sufficiently isolate the infringement signal to allow source interpretation. Using cell phones for data downloading might allow a network of such 1000-psi rated PAMP's to acoustically monitor a pipeline system and be trained by neural network software to positively identify and locate any pipeline infringement.

  7. Cascade Annealing of Tungsten Implanted with 5 keV Noble Gas Atoms : A Computer Simulation

    NARCIS (Netherlands)

    Kolk, G.J. van der; Veen, A. van; Caspers, L.M.; Hosson, J.Th.M. De

    1984-01-01

    The trapping of vacancies by implanted atoms is calculated. After low energy implantation (5 keV) of tungsten with heavy noble gas atoms most of the implanted atoms are in substitutional position with one or two vacancies closer than two lattice units. Under the influence of the lattice distortion a

  8. Experimental and Theoretical Studies of Pressure Broadened Alkali-Metal Atom Resonance Lines

    Science.gov (United States)

    Shindo, F.; Zhu, C.; Kirby, K.; Babb, J. F.

    2006-01-01

    We are carrying out a joint theoretical and experimental research program to study the broadening of alkali atom resonance lines due to collisions with helium and molecular hydrogen for applications to spectroscopic studies of brown dwarfs and extrasolar giant planets.

  9. Measurement of Velocity Distribution in Atomic Beam by Diode Laser with Narrow Line width

    Institute of Scientific and Technical Information of China (English)

    CHEN Jingbiao; WANG Fengzhi; YANG Donghai; WANG YiQiu

    2001-01-01

    In this paper, by using the detecting laser beam interacts with the atomic beam at a sharp angle and the Doppler frequency shift effect, the velocity distribution in cesium atomic beam is measured with a diode laser of narrow linewidth of 1 MHz. The effects of the atomic natural line width and cycling transition detecting factor on the measured results have been analyzed. Finally, the measured results have been compared with the theoretical calculation.

  10. The Impact of Diffuse Ionized Gas on Emission-line Ratios and Gas Metallicity Measurements

    Science.gov (United States)

    Zhang, Kai; Yan, Renbin; MaNGA Team

    2016-01-01

    Diffuse Ionized Gas (DIG) is prevalent in star-forming galaxies. Using a sample of galaxies observed by MaNGA, we demonstrate how DIG in star-forming galaxies impact the measurements of emission line ratios, hence the gas-phase metallicity measurements and the interpretation of diagnostic diagrams. We demonstrate that emission line surface brightness (SB) is a reasonably good proxy to separate HII regions from regions dominated by diffuse ionized gas. For spatially-adjacent regions or regions at the same radius, many line ratios change systematically with emission line surface brightness, reflecting a gradual increase of dominance by DIG towards low SB. DIG could significantly bias the measurement of gas metallicity and metallicity gradient. Because DIG tend to have a higher temperature than HII regions, at fixed metallicity DIG displays lower [NII]/[OII] ratios. DIG also show lower [OIII]/[OII] ratios than HII regions, due to extended partially-ionized regions that enhance all low-ionization lines ([NII], [SII], [OII], [OI]). The contamination by DIG is responsible for a substantial portion of the scatter in metallicity measurements. At different surface brightness, line ratios and line ratio gradients can differ systematically. As DIG fraction could change with radius, it can affect the metallicity gradient measurements in systematic ways. The three commonly used strong-line metallicity indicators, R23, [NII]/[OII], O3N2, are all affected in different ways. To make robust metallicity gradient measurements, one has to properly isolate HII regions and correct for DIG contamination. In line ratio diagnostic diagrams, contamination by DIG moves HII regions towards composite or LINER-like regions.

  11. Panola NGL (natural gas liquid) line laid in east Texas

    Energy Technology Data Exchange (ETDEWEB)

    1982-11-01

    Construction is complete on the Panola Products Pipeline Co. 8-in. NGL line in E. Texas. The 60-mile pipeline, which traverses rolling timber country, lightly developed commercial areas, and low-lying wetlands, will ultimately gather liquids from gas plants in E. Texas. Initially, this system is designed to transport natural gas liquids mix from the Carthage Plant, operated by Champlin Petroleum Co., to Gulf Pipeline Co.'s injection station at Lufkin, Texas. Final delivery will be made to various petrochemical facilities in the Mont Belvieu, Texas area. To minimize right-of-way problems, the line was routed parallel to an existing United Gas 22-in. pipeline for a distance of 36 miles from Carthage to near Nacogdoches. The pipeline has a design pressure of 1,480 psi. A back pressure of approx. 450 psi will be maintained on the line at all times to keep the mix in a liquid state. The predominant pipe used along the route is API 5LX-52 with a wall thickness of 0.219-in. Heavier wall thickness pipe, up to 0.375-in., is used for road, railroad, and major water crossings.

  12. Molecular and atomic line surveys of galaxies I: the dense, star-forming phase as a beacon

    CERN Document Server

    Geach, James E

    2012-01-01

    We predict the space density of molecular gas reservoirs in the Universe, and place a lower limit on the number counts of carbon monoxide (CO), hydrogen cyanide (HCN) molecular and [CII] atomic emission lines in blind redshift surveys in the submillimeter-centimeter spectral regime. Our model uses: (a) recently available HCN Spectral Line Energy Distributions (SLEDs) of local Luminous Infrared Galaxies (LIRGs, L_IR>10^11 L_sun), (b) a value for epsilon=SFR/M_dense(H_2) provided by new developments in the study of star formation feedback on the interstellar medium and (c) a model for the evolution of the infrared luminosity density. Minimal 'emergent' CO SLEDs from the dense gas reservoirs expected in all star-forming systems in the Universe are then computed from the HCN SLEDs since warm, HCN-bright gas will necessarily be CO-bright, with the dense star-forming gas phase setting an obvious minimum to the total molecular gas mass of any star-forming galaxy. We include [CII] as the most important of the far-inf...

  13. All-optical production and trapping of metastable noble gas atoms down to the single atom regime

    CERN Document Server

    Kohler, M; Sahling, P; Sieveke, C; Jerschabek, N; Kalinowski, M B; Becker, C; Sengstock, K

    2014-01-01

    The determination of isotope ratios of noble gas atoms has many applications e.g. in physics, nuclear arms control, and earth sciences. For several applications, the concentration of specific noble gas isotopes (e.g. Kr and Ar) is so low that single atom detection is highly desirable for a precise determination of the concentration. As an important step in this direction, we demonstrate operation of a krypton Atom Trap Trace Analysis (ATTA) setup based on a magneto-optical trap (MOT) for metastable Kr atoms excited by all-optical means. Compared to other state-of-the-art techniques for preparing metastable noble gas atoms, all-optical production is capable of overcoming limitations regarding minimal probe volume and avoiding cross-contamination of the samples. In addition, it allows for a compact and reliable setup. We identify optimal parameters of our experimental setup by employing the most abundant isotope Kr-84, and demonstrate single atom detection within a 3D MOT.

  14. A dense gas of laser-cooled atoms for hybrid atom-ion trapping

    Science.gov (United States)

    Höltkemeier, Bastian; Glässel, Julian; López-Carrera, Henry; Weidemüller, Matthias

    2017-01-01

    We describe the realization of a dark spontaneous-force trap of rubidium atoms. The atoms are loaded from a beam provided by a two-dimensional magneto-optical trap yielding a capture efficiency of 75%. The dense and cold atomic sample is characterized by saturated absorption imaging. Up to 10^9 atoms are captured with a loading rate of 3× 10^9 atoms/s into a cloud at a temperature of 250 μK with the density exceeding 10^{11} atoms/cm^3. Under steady-state conditions, more than 90% of the atoms can be prepared into the absolute atomic ground state, which provides favorable conditions for the investigation of sympathetic cooling of ions in a hybrid atom-ion trap.

  15. Investigation of accelerated neutral atom beams created from gas cluster ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Kirkpatrick, A., E-mail: akirkpatrick@exogenesis.us [Exogenesis Corporation, 20 Fortune Drive, Billerica, MA 01821 (United States); Kirkpatrick, S.; Walsh, M.; Chau, S.; Mack, M.; Harrison, S.; Svrluga, R.; Khoury, J. [Exogenesis Corporation, 20 Fortune Drive, Billerica, MA 01821 (United States)

    2013-07-15

    A new concept for ultra-shallow processing of surfaces known as accelerated neutral atom beam (ANAB) technique employs conversion of energetic gas cluster ions produced by the gas cluster ion beam (GCIB) method into intense collimated beams of coincident neutral gas atoms having controllable average energies from less than 10 eV per atom to beyond 100 eV per atom. A beam of accelerated gas cluster ions is first produced as is usual in GCIB, but conditions within the source ionizer and extraction regions are adjusted such that immediately after ionization and acceleration the clusters undergo collisions with non-ionized gas atoms. Energy transfer during these collisions causes the energetic cluster ions to release many of their constituent atoms. An electrostatic deflector is then used to eliminate charged species, leaving the released neutral atoms to still travel collectively at the same velocities they had as bonded components of their parent clusters. Upon target impact, the accelerated neutral atom beams produce effects similar to those normally associated with GCIB, but to shallower depths, with less surface damage and with superior subsurface interfaces. The paper discusses generation and characterization of the accelerated neutral atom beams, describes interactions of the beams with target surfaces, and presents examples of ongoing work on applications for biomedical devices.

  16. Tracing Inflows and Outflows with Absorption Lines in Circumgalactic Gas

    CERN Document Server

    Ford, Amanda Brady; Oppenheimer, Benjamin D; Katz, Neal; Kollmeier, Juna A; Thompson, Robert; Weinberg, David H

    2013-01-01

    We examine how HI and metal absorption lines within low-redshift galaxy halos trace the dynamical state of circumgalactic gas, using cosmological hydrodynamic simulations that include a well-vetted heuristic model for galactic outflows. We categorize inflowing, outflowing, and ambient gas based on its history and fate as tracked in our simulation. Following our earlier work showing that the ionisation level of absorbers was a primary factor in determining the physical conditions of absorbing gas, we show here that it is also a governing factor for its dynamical state. Low-ionisation metal absorbers (e.g. MgII) tend to arise in gas that will fall onto galaxies within several Gyr, while high-ionisation metal absorbers (e.g. OVI) generally trace material that was deposited by outflows many Gyr ago. Inflowing gas is dominated by enriched material that was previously ejected in an outflow, hence accretion at low redshifts is typically substantially enriched. Recycling wind material is preferentially found closer t...

  17. On-line experimental results of an argon gas cell-based laser ion source (KEK Isotope Separation System)

    Science.gov (United States)

    Hirayama, Y.; Watanabe, Y. X.; Imai, N.; Ishiyama, H.; Jeong, S. C.; Jung, H. S.; Miyatake, H.; Oyaizu, M.; Kimura, S.; Mukai, M.; Kim, Y. H.; Sonoda, T.; Wada, M.; Huyse, M.; Kudryavtsev, Yu.; Van Duppen, P.

    2016-06-01

    KEK Isotope Separation System (KISS) has been developed at RIKEN to produce neutron rich isotopes with N = 126 to study the β -decay properties for application to astrophysics. The KISS is an element-selective mass-separation system which consists of an argon gas cell-based on laser ion source for atomic number selection and an ISOL mass-separation system. The argon gas cell of KISS is a key component to stop and collect the unstable nuclei produced in a multi-nucleon transfer reaction, where the isotopes of interest will be selectively ionized using laser resonance ionization. We have performed off- and on-line experiments to study the basic properties of the gas cell as well as of the KISS. We successfully extracted the laser-ionized stable 56Fe (direct implantation of a 56Fe beam into the gas cell) atoms and 198Pt (emitted from the 198Pt target by elastic scattering with a 136Xe beam) atoms from the KISS during the commissioning on-line experiments. We furthermore extracted laser-ionized unstable 199Pt atoms and confirmed that the measured half-life was in good agreement with the reported value.

  18. Iridium single atom tips fabricated by field assisted reactive gas etching

    Science.gov (United States)

    Wood, John A.; Urban, Radovan; Salomons, Mark; Cloutier, Martin; Wolkow, Robert A.; Pitters, Jason L.

    2016-03-01

    We present a simple, reliable method to fabricate Ir single atom tips (SATs) from polycrystalline wire. An electrochemical etch in CaCl2 solution is followed by a field assisted reactive gas etch in vacuum at room temperature using oxygen as an etching gas and neon as an imaging gas. Once formed, SATs are cooled to liquid nitrogen temperatures and their underlying structure is examined through evaporation of the apex atoms. Furthermore, a method is developed to repair Ir SATs at liquid nitrogen temperatures when apex atoms evaporate. This method may be used to fabricate Ir SAT ion sources.

  19. A quantum transport model for atomic line radiation in plasmas*

    Science.gov (United States)

    Rosato, Joël

    2017-02-01

    Emission and absorption lines in plasmas are investigated theoretically using a phase space formulation of quantum electrodynamics. A transport equation for the one-photon Wigner function is derived and formulated in terms of the noncommutative Moyal product. This equation reduces to the standard radiative transfer equation at the large spectral band limit, when the characteristic spectral band of the emission and absorption coefficients is larger than the inverse photon absorption length and time. We examine deviations to this limit. An ideal slab geometry is considered. The Wigner function relative to hydrogen Lyman α in stellar atmospheric conditions is calculated.

  20. 21 CFR 870.4410 - Cardiopulmonary bypass in-line blood gas sensor.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass in-line blood gas sensor... Cardiopulmonary bypass in-line blood gas sensor. (a) Identification. A cardiopulmonary bypass in-line blood gas sensor is a transducer that measures the level of gases in the blood. (b) Classification. Class...

  1. Gas insulated transmission line having low inductance intercalated sheath

    Science.gov (United States)

    Cookson, Alan H.

    1978-01-01

    A gas insulated transmission line including an outer sheath, an inner conductor disposed within the outer sheath, and an insulating gas between the inner conductor and the outer sheath. The outer sheath comprises an insulating tube having first and second ends, and having interior and exterior surfaces. A first electrically conducting foil is secured to the interior surface of the insulating tube, is spirally wound from one tube end to the second tube end, and has a plurality of overlapping turns. A second electrically conducting foil is secured to the exterior surface of the insulating tube, and is spirally wound in the opposite direction from the first electrically conducting foil. By winding the foils in opposite directions, the inductances within the intercalated sheath will cancel each other out.

  2. Luther-Emery Phase and Atomic-Density Waves in a Trapped Fermion Gas

    Science.gov (United States)

    Xianlong, Gao; Rizzi, M.; Polini, Marco; Fazio, Rosario; Tosi, M. P.; Campo, V. L., Jr.; Capelle, K.

    2007-01-01

    The Luther-Emery liquid is a state of matter that is predicted to occur in one-dimensional systems of interacting fermions and is characterized by a gapless charge spectrum and a gapped spin spectrum. In this Letter we discuss a realization of the Luther-Emery phase in a trapped cold-atom gas. We study by means of the density-matrix renormalization-group technique a two-component atomic Fermi gas with attractive interactions subject to parabolic trapping inside an optical lattice. We demonstrate how this system exhibits compound phases characterized by the coexistence of spin pairing and atomic-density waves. A smooth crossover occurs with increasing magnitude of the atom-atom attraction to a state in which tightly bound spin-singlet dimers occupy the center of the trap. The existence of atomic-density waves could be detected in the elastic contribution to the light-scattering diffraction pattern.

  3. Observing random walks of atoms in buffer gas through resonant light absorption

    CERN Document Server

    Aoki, Kenichiro

    2016-01-01

    Using resonant light absorption, random walk motions of rubidium atoms in nitrogen buffer gas are observed directly. The transmitted light intensity through atomic vapor is measured and its spectrum is obtained, down to orders of magnitude below the shot noise level to detect fluctuations caused by atomic motions. To understand the measured spectra, the spectrum for atoms performing random walks in a gaussian light beam is computed and its analytical form is obtained. The spectrum has $1/f^2$ ($f$: frequency) behavior at higher frequencies, crossing over to a different, but well defined behavior at lower frequencies. The properties of this theoretical spectrum agree excellently with the measured spectrum. This understanding also enables us to obtain the diffusion constant, the photon cross section of atoms in buffer gas and the atomic number density, from a single spectral measurement. We further discuss other possible applications of our experimental method and analysis.

  4. Atom-molecule equilibration in a degenerate Fermi gas with resonant interactions

    DEFF Research Database (Denmark)

    Williams, J. E.; Nikuni, T.; Nygaard, Nicolai;

    2004-01-01

    We present a nonequilibrium kinetic theory describing atom-molecule population dynamics in a two-component Fermi gas with a Feshbach resonance. Key collision integrals emerge that govern the relaxation of the atom-molecule mixture to chemical and thermal equilibrium. Our focus is on the pseudogap...

  5. Novel Applications of Buffer-Gas Cooling to Cold Atoms, Diatomic Molecules, and Large Molecules

    OpenAIRE

    Drayna, Garrett Korda

    2016-01-01

    Cold gases of atoms and molecules provide a system for the exploration of a diverse set of physical phenomena. For example, cold gasses of magnetically and electrically polar atoms and molecules are ideal systems for quantum simulation and quantum computation experiments, and cold gasses of large polar molecules allow for novel spectroscopic techniques. Buffer-gas cooling is a robust and widely applicable method for cooling atoms and molecules to temperatures of approximately 1 Kelvin. In thi...

  6. Atomic Interaction Effects on Electromagnetically Induced Transparency and Slow Light in Ultracold Bose Gas

    Institute of Scientific and Technical Information of China (English)

    胡正峰; 杜春光; 李代军; 李师群

    2002-01-01

    We investigate electromagnetically induced transparency and slow group velocity of light in ultracold Bose gas with a two-photon Raman process. The properties of electromagnetically induced transparency and light speed can be changed by controlling the atomic interaction. Atomic interaction can be used as a knob to control the optical properties of atomic media. This can be realized in experiment by using the Feshbach resonance technique.

  7. Atomic far-IR fine-structure line mapping of L1630, M17, and W3: Comparison of (O I) and (C II) distributions

    Science.gov (United States)

    Howe, J. E.; Jaffe, Dan T.; Zhou, Shudong

    1995-01-01

    We mapped the distribution of atomic far-IR line emission from (O I) and (C II) over parsec scales in the Galactic star-forming regions L1630, M17, and W3 using the MPE Far-Infrared Fabry-Perot Imaging spectrometer (FIFI) on board the NASA Kuiper Airborne Observatory. The lines mapped include (O I) 63 microns, (O I) 146 microns, and (C II) 158 microns. Comparison of the intensities and ratios of these lines with models of photodissociation regions (e.g., Tielens & Hollenbach 1985, ApJ, 344, 770) allows us to derive temperatures and densities of the primarily neutral atomic gas layers lying on the surfaces of UV-illuminated molecular gas. In general, the (C II) line arises ubiquitously throughout the molecular clouds while the (O I) lines are mainly confined to warm, dense gas (T is greater than 100 K, n is greater than 10(exp 4)/cu cm) near the sites of O and B stars. The distribution of (C II) in the star-forming clouds implies that the (C II) emission arises on the surfaces of molecular clumps throughout the clouds, rather than only at the boundary layer between molecular gas and H II regions.

  8. Atom Resonance Lines for Modeling Atmosphere: Studies of Pressure-Broadening of Alkali Atom Resonance Lines for Modeling Atmospheres of Extrasolar Giant Planets and Brown Dwarfs

    Science.gov (United States)

    Hasan, Hashima (Technical Monitor); Kirby, K.; Babb, J.; Yoshino, K.

    2005-01-01

    We report on progress made in a joint program of theoretical and experimental research to study the line-broadening of alkali atom resonance lines due to collisions with species such as helium and molecular hydrogen. Accurate knowledge of the line profiles of Na and K as a function of temperature and pressure will allow such lines to serve as valuable diagnostics of the atmospheres of brown dwarfs and extra-solar giant planets. A new experimental apparatus has been designed, built and tested over the past year, and we are poised to begin collecting data on the first system of interest, the potassium resonance lines perturbed by collisions with helium. On the theoretical front, calculations of line-broadening due to sodium collisions with helium are nearly complete, using accurate molecular potential energy curves and transition moments just recently computed for this system. In addition we have completed calculations of the three relevant potential energy curves and associated transition moments for K - He, using the MOLPRO quantum chemistry codes. Currently, calculations of the potential surfaces describing K-H2 are in progress.

  9. Outflowing atomic and molecular gas at z ~ 0.67 towards 1504 + 377

    Science.gov (United States)

    Kanekar, Nissim; Chengalur, Jayaram N.

    2008-02-01

    We report the detection of OH 1667-MHz and wide HI 21-cm absorption at z ~ 0.67 towards the red quasar 1504 + 377, with the Green Bank Telescope and the Giant Metrewave Radio Telescope. The HI 21-cm absorption extends over a velocity range of ~600kms-1 blueward of the quasar redshift (z = 0.674), with the new OH 1667-MHz absorption component at ~-430kms-1, nearly coincident with earlier detections of millimetre-wave absorption at z ~ 0.6715. The atomic and molecular absorption appear to arise from a fast gas outflow from the quasar, with a mass outflow rate and a molecular hydrogen fraction . The radio structure of 1504 + 377 is consistent with the outflow arising as a result of a jet-cloud interaction, followed by rapid cooling of the cloud material. The observed ratio of HCO+ and OH column densities is ~20 times higher than typical values in Galactic and high-z absorbers. This could arise because of small-scale structure in the outflowing gas on sub-parsec scales, which would also explain the observed variability in the HI 21-cm line.

  10. Diffuse Atomic and Molecular Gas near IC443

    CERN Document Server

    Hirschauer, A; Wallerstein, George; Means, T

    2009-01-01

    We present an analysis of results on absorption from Ca II, Ca I, K I, and the molecules CH+, CH, C2, and CN that probes gas interacting with the supernova remnant IC443. The eleven directions sample material across the visible nebula and beyond its eastern edge. Most of the neutral material, including the diatomic molecules, is associated with the ambient cloud detected via H I and CO emission. Analysis of excitation and chemistry yields gas densities that are typical of diffuse molecular gas. The low density gas probed by Ca II extends over a large range in velocities, from -120 to +80 km/s in the most extreme cases. This gas is distributed among several velocity components, unlike the situation for the shocked molecular clumps, whose emission occurs over much the same range but as very broad features. The extent of the high-velocity absorption suggests a shock velocity of 100 km/s for the expanding nebula.

  11. Diffuse Atomic and Molecular Gas in the Interstellar Medium of M82 toward SN 2014J

    CERN Document Server

    Ritchey, Adam M; Dahlstrom, Julie A; York, Donald G

    2014-01-01

    We present a comprehensive analysis of interstellar absorption lines seen in moderately-high resolution, high S/N ratio optical spectra of SN 2014J in M82. Our observations were acquired over the course of six nights, covering the period from ~7 days before to ~29 days after the supernova reached its maximum V-band brightness. Complex interstellar absorption is observed from Na I, Ca II, K I, Ca I, CH+, CH, and CN, much of which arises from gas in the interstellar medium of M82, although absorption features associated with the Galactic disk and halo are also observed. We detect Li I absorption over a range in velocity consistent with that exhibited by the strongest Na I and K I components associated with M82; this is the first detection of interstellar Li in a galaxy outside of the Local Group. There are no significant temporal variations in the absorption-line profiles over the 37 days sampled by our observations. The relative abundances of the observed atomic and molecular species reveal that the ISM of M82...

  12. Broadening of the Spectral Atomic Lines Analysis in High Density Argon Corona Plasma by Using Voigt Profile

    Science.gov (United States)

    Nur, M.; Bonifaci, N.; Denat, A.; Atrazhev, V. M.

    2015-06-01

    Studies of spectrum emission from high density argon plasma corona has been done. The analysis of the boardening of spectral atomic lines of Ar-I profile has been curried out by using an empirical approximation based on a Voigt profile. Full-width at half-maximum (FWHM) of the spectral-lines of 763.5 nm has been determined from atmospheric pressure until liquid state. The study liquid argon was curried out in a variation of temperature from K to 151.2 K and hydrostatics pressure from 2.1 MPa to 6.4 MPa. These pressure gives the densities N∞ (i.e. density very far from ionization zone) a variation from 1.08 1022 to 2.11 1022 cm-3. FWHM of Voigt approximation (Wv) of the line 763,5 nm of 'Ar I for: the emission lamp very low pressure (Wv = 0,160 nm) and our corona discharge at a pressure of MPa (Wv = 0,67 nm) and at a pressure of 9,5 MPa (Wv = 1,16 nm). In gas, corona plasma has been generated from 0.1 MPa to 9.5 MPa. We found that the broadening spectral line increase by increasing densities both for. the spectral-lines of 763.5 nm and 696.5 nm. We concluded that broadening of spectrum cause of Van der Waals force.

  13. Measurements of transition probabilities for spin-changing lines of atomic ions used in diagnostics of astrophysical plasmas

    Science.gov (United States)

    Smith, P. L.; Johnson, B. C.; Kwong, H. S.; Parkinson, W. H.; Knight, R. D.

    1984-01-01

    The intensities of ultraviolet, spin-changing, 'intersystem' lines of low-Z atomic ions are frequently used in determinations of electron densities and temperatures in astrophysical plasmas as well as in measurements of element abundances in the interstellar gas. The transition probabilities (A-values) of these lines, which are about five orders of magnitude weaker than allowed lines, have not been measured heretofore and various calculations produce A-values for these lines that differ by as much as 50 percent A radio-frequency ion trap has been used for the first measurements of transition probabilities for intersystem lines seen in astronomical spectra. The measurement procedure is discussed and results for Si III, O III, N II, and C III are reviewed and compared to calculated values. Discrepancies exist; these indicate that some of the calculated A-values may be less reliable than has been beleived and that revisions to the electron densities determined for some astrophysical plasmas may be required.

  14. Influence of the atomic mass of the background gas on laser ablation plume propagation

    DEFF Research Database (Denmark)

    Amoruso, Salvatore; Schou, Jørgen; Lunney, James G.

    2008-01-01

    A combination of time-of-flight ion probe measurements and gas dynamical modeling has been used to investigate the propagation of a laser ablation plume in gases of different atomic/molecular weight. The pressure variation of the ion time-of-flight was found to be well described by the gas...... dynamical model of Predtechensky and Mayorov (Appl. Supercond. 1:2011, 1993). In particular, the model describes how the pressure required to stop the plume in a given distance depends on the atomic/molecular weight of the gas, which is a feature that cannot be explained by standard point...

  15. Effects of Carrier Gas Conditions on Concentration of Alcohol Aqueous Solution by Ultrasonic Atomization

    Science.gov (United States)

    Yasuda, Keiji; Tanaka, Naofumi; Rong, Lei; Nakamura, Masaaki; Li, Li; Oda, Akiyoshi; Kawase, Yasuhito

    2003-05-01

    The effects of carrier gas conditions on the concentration of ethanol by ultrasonic atomization are examined. With increasing height from vessel bottom to gas inlet and outlet, the ethanol content in the accompanied liquid increases and the flow rate of alcohol decreases. The ethanol content in the accompanied liquid becomes lower as the gas velocity becomes higher. The attachment of a demister is effective for the increase of the content in the accompanied liquid.

  16. Magnetic-field-driven localization of light in a cold-atom gas

    CERN Document Server

    Skipetrov, S E

    2014-01-01

    We discover a transition from extended to localized quasi-modes for light in a gas of immobile two-level atoms in a magnetic field. The transition takes place either upon increasing the number density of atoms in a strong field or upon increasing the field at a high enough density. It has many characteristic features of a disorder-driven (Anderson) transition but is strongly influenced by near-field interactions between atoms and the anisotropy of the atomic medium induced by the magnetic field.

  17. Spectral line shifts of alkali atoms in liquid helium: a relativistic density functional approach

    Energy Technology Data Exchange (ETDEWEB)

    Anton, J [Universitaet Kassel, Institut fuer Physik, 34109 Kassel (Germany); Mukherjee, P K [Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700 032 (India); Fricke, B [Universitaet Kassel, Institut fuer Physik, 34109 Kassel (Germany); Fritzsche, S [Universitaet Kassel, Institut fuer Physik, 34109 Kassel (Germany)

    2007-06-28

    Excitation line shifts of the principal resonance transitions in alkali atoms sodium and cesium embedded inside the liquid helium environment have been calculated using four-component relativistic density functional theory. The effect of the liquid helium environment is assumed to be represented by a cluster of 14 atoms surrounding the central alkali atom. The estimated blue shift of the principal resonance line {sup 2}S {yields}{sup 2}P is 22.8 nm for Na and 16.7 nm for Cs. The result for Cs is in good agreement with the experimental shift of 18.2 nm. In the absence of the experimental data for Na, our result is compared with those of other theoretical estimates.

  18. The intensity calculation of the gas absorption line by multi-line Voigt fitting

    Institute of Scientific and Technical Information of China (English)

    ZHOU Meng-ran; LI Zhen-bi; ZHONG Ming-yu; HE Gang

    2008-01-01

    Adopted the distribution feedback type (DFB) laser to measure the coal minegas methane,according to the methane located 1.6 pm nearby 2 v3 with a R9 direct ab-sorption spectrum,attraction wire intensity of each line was calculated through the multi-line Voigt fitting.The experimental result indicates that in the obtained four attraction recover of wire,the maximum deviation is 2.7%,and the minimum deviation is 0.02%,other results are all in experimental error scope.This research method may apply in the spectrum survey methane gas density,it has characteristics including high precision,strong selectivity,fast response and so on.

  19. Determining protoplanetary disk gas masses from CO isotopologues line observations

    CERN Document Server

    Miotello, Anna; Kama, Mihkel; Bruderer, Simon

    2016-01-01

    Despite intensive studies of protoplanetary disks, there is still no reliable way to determine their total mass and their surface density distribution, quantities that are crucial for describing both the structure and the evolution of disks up to the formation of planets. The goal of this work is to use less abundant CO isotopologues, whose detection is routine for ALMA, to infer the gas mass of disks. Isotope-selective effects need to be taken into account in the analysis, because they can significantly modify CO isotopologues line intensities. CO isotope-selective photodissociation has been implemented in the physical-chemical code DALI and 800 disk models have been run for a range of disk and stellar parameters. Dust and gas temperature structures have been computed self-consistently, together with a chemical calculation of the main species. Both disk structure and stellar parameters have been investigated. Total fluxes have been ray-traced for different CO isotopologues and for various transitions for dif...

  20. Narrow-line diode laser system for laser cooling of strontium atoms on the intercombination transition

    Science.gov (United States)

    Li, Y.; Ido, T.; Eichler, T.; Katori, H.

    We report a diode laser system developed for narrow-line cooling and trapping on the 1S0-3P1 intercombination transition of neutral strontium atoms. Doppler cooling on this spin-forbidden transition with a line width of Γ/2π=7.1 kHz enables us to achieve sub-μK temperatures in a two-step cooling process. The required reduction of the laser line width to the kHz level was achieved by locking the laser to a tunable Fabry-Pérot cavity. The long-term drift (>0.1 s) of the reference cavity was compensated by employing the saturated absorption signal obtained from Sr vapor in a heat pipe of novel design. We demonstrate the potential of the system by performing spectroscopy of Sr atoms confined to the Lamb-Dicke regime in a one-dimensional optical lattice.

  1. Novel Applications of Buffer-gas Cooling to Cold Atoms, Diatomic Molecules, and Large Molecules

    Science.gov (United States)

    Drayna, Garrett Korda

    Cold gases of atoms and molecules provide a system for the exploration of a diverse set of physical phenomena. For example, cold gasses of magnetically and electrically polar atoms and molecules are ideal systems for quantum simulation and quantum computation experiments, and cold gasses of large polar molecules allow for novel spectroscopic techniques. Buffer-gas cooling is a robust and widely applicable method for cooling atoms and molecules to temperatures of approximately 1 Kelvin. In this thesis, I present novel applications of buffer-gas cooling to obtaining gases of trapped, ultracold atoms and diatomic molecules, as well as the study of the cooling of large organic molecules. In the first experiment of this thesis, a buffer-gas beam source of atoms is used to directly load a magneto-optical trap. Due to the versatility of the buffer-gas beam source, we obtain trapped, sub-milliKelvin gases of four different lanthanide species using the same experimental apparatus. In the second experiment of this thesis, a buffer-gas beam is used as the initial stage of an experiment to directly laser cool and magneto-optically trap the diatomic molecule CaF. In the third experiment of this thesis, buffer-gas cooling is used to study the cooling of the conformational state of large organic molecules. We directly observe conformational relaxation of gas-phase 1,2-propanediol due to cold collisions with helium gas. Lastly, I present preliminary results on a variety of novel applications of buffer-gas cooling, such as mixture analysis, separation of chiral mixtures, the measurement of parity-violation in chiral molecules, and the cooling and spectroscopy of highly unstable reaction intermediates.

  2. Low-excitation atomic gas around evolved stars I. ISO observations of C-rich nebulae

    NARCIS (Netherlands)

    Fong, D; Meixner, M; Castro-Carrizo, A; Bujarrabal, [No Value; Latter, WB; Tielens, AGGM; Kelly, DM; Sutton, EC

    2001-01-01

    We present ISO LWS and SWS spectra of far-infrared (FIR) atomic fine structure lines in 12 carbon-rich evolved stars including asymptotic giant branch (AGB) stars, proto-planetary nebulae (PPNe) and planetary nebulae (PNe). The spectra include grating and Fabry-Perot measurements of the line emissio

  3. Galaxy Zoo and ALFALFA: Atomic Gas and the Regulation of Star Formation in Barred Disc Galaxies

    CERN Document Server

    Masters, Karen L; Haynes, Martha P; Keel, William C; Lintott, Chris; Simmons, Brooke; Skibba, Ramin; Bamford, Steven; Giovanelli, Riccardo; Schawinski, Kevin

    2012-01-01

    We study the observed correlation between atomic gas content and the likelihood of hosting a large scale bar in a sample of 2090 disc galaxies. Such a test has never been done before on this scale. We use data on morphologies from the Galaxy Zoo project and information on the galaxies' HI content from the ALFALFA blind HI survey. Our main result is that the bar fraction is significantly lower among gas rich disc galaxies than gas poor ones. This is not explained by known trends for more massive (stellar) and redder disc galaxies to host more bars and have lower gas fractions: we still see at fixed stellar mass a residual correlation between gas content and bar fraction. We discuss three possible causal explanations: (1) bars in disc galaxies cause atomic gas to be used up more quickly, (2) increasing the atomic gas content in a disc galaxy inhibits bar formation, and (3) bar fraction and gas content are both driven by correlation with environmental effects (e.g. tidal triggering of bars, combined with strangu...

  4. Molecular and atomic gas in the Local Group galaxy M 33

    Science.gov (United States)

    Gratier, P.; Braine, J.; Rodriguez-Fernandez, N. J.; Schuster, K. F.; Kramer, C.; Xilouris, E. M.; Tabatabaei, F. S.; Henkel, C.; Corbelli, E.; Israel, F.; van der Werf, P. P.; Calzetti, D.; Garcia-Burillo, S.; Sievers, A.; Combes, F.; Wiklind, T.; Brouillet, N.; Herpin, F.; Bontemps, S.; Aalto, S.; Koribalski, B.; van der Tak, F.; Wiedner, M. C.; Röllig, M.; Mookerjea, B.

    2010-11-01

    We present high-resolution large-scale observations of the molecular and atomic gas in the Local Group galaxy M 33. The observations were carried out using the HEterodyne Receiver Array (HERA) at the 30 m IRAM telescope in the CO(2-1) line, achieving a resolution of 12” × 2.6 km s-1, enabling individual giant molecular clouds (GMCs) to be resolved. The observed region is 650 square arcminutes mainly along the major axis and out to a radius of 8.5 kpc, and covers entirely the 2' × 40' radial strip observed with the HIFI and PACS Spectrometers as part of the HERM33ES Herschel key program. The achieved sensitivity in main-beam temperature is 20-50 mK at 2.6 km s-1 velocity resolution. The CO(2-1) luminosity of the observed region is 1.7±0.1 × 107 K km s-1 pc2 and is estimated to be 2.8±0.3 × 107 K km s-1 pc2 for the entire galaxy, corresponding to H2 masses of 1.9 × 108 Msun and 3.3 × 108 Msun respectively (including He), calculated with N(H2)/ICO(1-0) twice the Galactic value due to the half-solar metallicity of M 33. The H i 21 cm VLA archive observations were reduced, and the mosaic was imaged and cleaned using the multi-scale task in the CASA software package, yielding a series of datacubes with resolutions ranging from 5” to 25”. The H i mass within a radius of 8.5 kpc is estimated to be 1.4 × 109 Msun. The azimuthally averaged CO surface brightness decreases exponentially with a scale length of 1.9±0.1 kpc whereas the atomic gas surface density is constant at ΣH I = 6±2 Msun pc-2 deprojected to face-on. For an N(H2)/ICO(1-0) conversion factor twice that of the Milky Way, the central kiloparsec H2 surface density is ΣH2 = 8.5±0.2 Msun pc-2. The star formation rate per unit molecular gas (SF efficiency, the rate of transformation of molecular gas into stars), as traced by the ratio of CO to Hα and FIR brightness, is constant with radius. The SFE, with a N(H2)/ICO(1-0) factor twice galactic, appears 2-4 times greater than for large spiral

  5. Probing the Physical Conditions of Atomic Gas at High Redshift

    CERN Document Server

    Neeleman, Marcel; Wolfe, Arthur M

    2014-01-01

    A new method is used to measure the physical conditions of the gas in damped Lyman-alpha systems (DLAs). Using high resolution absorption spectra of a sample of 80 DLAs, we are able to measure the ratio of the upper to lower fine-structure levels of the ground state of C II and Si II. These ratios are determined solely by the physical conditions of the gas. We explore the allowed physical parameter space using a Monte Carlo Markov Chain method to constrain simultaneously the temperature, neutral hydrogen density, and electron density of each DLA. The results indicate that at least 5 % of all DLAs have the bulk of their gas in a dense, cold phase with typical densities of ~100 cm-3 and temperatures below 500 K. We further find that the typical pressure of DLAs in our sample is log(P/k) = 3.4 [K cm-3], which is comparable to the pressure of the local interstellar medium (ISM), and that the components containing the bulk of the neutral gas can be quite small with absorption sizes as small as a few parsec. We sho...

  6. LOW ENERGY BEAM-GAS SPECTROSCOPY OF HIGHLY IONISED ATOMS

    OpenAIRE

    Desesquelles, J.; DENIS A.; Druetta, M.; Martin, S.

    1989-01-01

    Features of low energy beam-gas spectroscopic source are reviewed and compared to those of other light sources. Measurement techniques are surveyed. They include the study of wavelength of heavy multiply charged ions in visible and u.v. ranges from normal excited states, doubly excited states, high n levels and doubly excited Rydberg levels.

  7. PROBING THE PHYSICAL CONDITIONS OF ATOMIC GAS AT HIGH REDSHIFT

    Energy Technology Data Exchange (ETDEWEB)

    Neeleman, Marcel; Wolfe, Arthur M. [Department of Physics and Center for Astrophysics and Space Sciences, UCSD, La Jolla, CA 92093 (United States); Prochaska, J. Xavier, E-mail: mneeleman@physics.ucsd.edu [Department of Astronomy and Astrophysics, UCO/Lick Observatory, 1156 High Street, University of California, Santa Cruz, CA 95064 (United States)

    2015-02-10

    A new method is used to measure the physical conditions of the gas in damped Lyα systems (DLAs). Using high-resolution absorption spectra of a sample of 80 DLAs, we are able to measure the ratio of the upper and lower fine-structure levels of the ground state of C{sup +} and Si{sup +}. These ratios are determined solely by the physical conditions of the gas. We explore the allowed physical parameter space using a Monte Carlo Markov chain method to constrain simultaneously the temperature, neutral hydrogen density, and electron density of each DLA. The results indicate that at least 5% of all DLAs have the bulk of their gas in a dense, cold phase with typical densities of ∼100 cm{sup –3} and temperatures below 500 K. We further find that the typical pressure of DLAs in our sample is log (P/k{sub B} ) = 3.4 (K cm{sup –3}), which is comparable to the pressure of the local interstellar medium (ISM), and that the components containing the bulk of the neutral gas can be quite small with absorption sizes as small as a few parsecs. We show that the majority of the systems are consistent with having densities significantly higher than expected for a purely canonical warm neutral medium, indicating that significant quantities of dense gas (i.e., n {sub H} > 0.1 cm{sup –3}) are required to match observations. Finally, we identify eight systems with positive detections of Si II*. These systems have pressures (P/k{sub B} ) in excess of 20,000 K cm{sup –3}, which suggest that these systems tag a highly turbulent ISM in young, star-forming galaxies.

  8. Flow lines and export lines of Sabalo Gas Field - the engineering of a complex job; Flow lines e export lines de Sabalo - a engenharia da complexidade

    Energy Technology Data Exchange (ETDEWEB)

    Serodio, Conrado Jose Morbach [GDK Engenharia, Salvador, BA (Brazil)

    2003-07-01

    The construction of the natural gas flow lines and export lines system of the Sabalo field, in the far South of Bolivia is an unique job in the pipeline construction area. Its execution is a turning point in terms of engineering and construction technology in this industry. Among the Aguarague Cordillera (mountains), it runs across rocky canyons for more than 5 km, a 2.100 mt long narrow tunnel to overcome the mountains and steep hills along all the ROW length, with a total extension of 70 km, in line pipes ranging from 10'' and 12'' for the flow lines, 28'' for the gas export line and 8' for the condensate line. An integrated construction work plan was settled in order to face and overcome the complex construction situations found in every feet of the pipeline. Four simultaneous work sites were mobilized, 8 independent work fronts, 700 professionals and more than 150 pieces of heavy construction equipment, brought from 3 different countries. Special techniques were adopted also to handle the challenging detail engineering . All in all, the correct conjunction of a sound engineering work, planning, human resources and equipment and the managing flexibility to create alternatives and solutions at the fast pace required by a dynamic work schedule were essential to succeed, in a job with no room for mistakes. The successfully job completion open new possibilities to other challenging projects alike.(author)

  9. Catalysis by Single Atoms: Water Gas Shift and Ethylene Hydrogenation

    Science.gov (United States)

    2009-04-20

    This adsorbed oxygen reacts with methane leading to combustion or partial oxidation to syngas at lower temperatures than in the existing commercial...600 Energy (eV) 28 To test the accuracy of reported ZrB2 atomic composition, we analyzed a hot-pressed ZrB2 sample supplied by Ceradyne. Fig. 26(a...specimens. 50um Electron Imaae 1 (a) (b) Figure 26. Analysis of boron-enriched ZrB2 sample supplied by Ceradyne: (a) SEM image (b) EDS counts (c

  10. Ionization cross sections for electron scattering from metastable rare-gas atoms (Ne* and Ar*)

    Institute of Scientific and Technical Information of China (English)

    Zhang Yong-Zhi; Zhou Ya-Jun

    2013-01-01

    The optical-model approach has been used to investigate the electron-impact ionization of metastable rare-gas atoms.A complex equivalent-local polarization potential is obtained to describe the ionization continuum channels.We have calculated the cross sections for collisional ionization of the metastable atoms Ne* and Ar* by electrons in the energy range from threshold to 200 eV.The present results are in agreement with the available experimental measurements and other theoretical calculations.

  11. Production and measurement of Bose-Einstein condensate of 87Rb atomic gas

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The research platform for Bose-Einstein condensate in 87Rb atomic gas, which is composed of a double MOT configuration and a QUIC trap, was reported. The properties of the condensate were measured both in time-of-flight and in tight confinement by the absorption imaging method. The measurements agreed with the criterions of Bose-Einstein condensation phase transition. About 2×105 atoms were pure condensed.

  12. Production and measurement of Bose-Einstein condensate of 87Rb atomic gas

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The research platform for Bose-Einstein condensate in 87 Rb atomic gas,which is composed of a double MOT configuration and a QUIC trap,was reported.The properties of the condensate were measured both in time-of-flight and in tight confinement by the absorption imaging method.The measurements agreed with the criterions of Bose-Einstein condensation phase transition.About 2×10 5 atoms were pure condensed.

  13. Development of Low Cost Gas Atomization of Precursor Powders for Simplified ODS Alloy Production

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver [Ames Lab., Ames, IA (United States)

    2014-08-05

    A novel gas atomization reaction synthesis (GARS) method was developed in this project to enable production (at our partner’s facility) a precursor Ni-Cr-Y-Ti powder with a surface oxide and an internal rare earth (RE) containing intermetallic compound (IMC) phase. Consolidation and heat-treatment experiments were performed at Ames Lab to promote the exchange of oxygen from the surface oxide to the RE intermetallic to form nano-metric oxide dispersoids. Alloy selection was aided by an internal oxidation and serial grinding experiments at Ames Lab and found that Hf-containing alloys may form more stable dispersoids than Ti-containing alloy, i.e., the Hf-containing system exhibited five different oxide phases and two different intermetallics compared to the two oxide phases and one intermetallic in the Ti-containing alloys. Since the simpler Ti-containing system was less complex to characterize, and make observations on the effects of processing parameters, the Ti-containing system was selected by Ames Lab for experimental atomization trials at our partner. An internal oxidation model was developed at Ames Lab and used to predict the heat treatment times necessary for dispersoid formation as a function of powder size and temperature. A new high-pressure gas atomization (HPGA) nozzle was developed at Ames Lab with the aim of promoting fine powder production at scales similar to that of the high gas-flow and melt-flow of industrial atomizers. The atomization nozzle was characterized using schlieren imaging and aspiration pressure testing at Ames Lab to determine the optimum melt delivery tip geometry and atomization pressure to promote enhanced secondary atomization mechanisms. Six atomization trials were performed at our partner to investigate the effects of: gas atomization pressure and reactive gas concentration on the particle size distribution (PSD) and the oxygen content of the resulting powder. Also, the effect on the rapidly solidified microstructure (as a

  14. Potential of two-line atomic fluorescence for temperature imaging in turbulent indium-oxide-producing flames

    Energy Technology Data Exchange (ETDEWEB)

    Münsterjohann, Bettina; Huber, Franz J. T.; Klima, Tobias C.; Holfelder, Sandra; Engel, Sascha R. [Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Lehrstuhl für Technische Thermodynamik (LTT) (Germany); Miller, Joseph D. [Aerospace Systems Directorate, Air Force Research Laboratory (United States); Meyer, Terrence R. [Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen Graduate School in Advanced Optical Technologies (SAOT) (Germany); Will, Stefan, E-mail: stefan.will@fau.de [Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Lehrstuhl für Technische Thermodynamik (LTT) (Germany)

    2015-11-15

    The applicability of two-line atomic fluorescence (TLAF) for temperature imaging in an indium-based flame spray pyrolysis (FSP) process is demonstrated using a single tunable optical parametric oscillator (OPO) to generate the required excitation wavelengths consecutively. Single-shot images of the detected fluorescence signals demonstrate that the signal levels in the flame are suitable for evaluation of temperature and verify the capability and potential of the measurement technique directly during particle formation without additional indium seeding. Qualitative averaged two-dimensional temperature distributions in the FSP flame are presented, showing the influence of varying sheath gas flow rates on the resulting temperature distribution. With the addition of a second OPO and detection system, the two fluorescence signals acquired consecutively in this work could be obtained simultaneously and enable spatio-temporally resolved single-shot temperature measurements in flame synthesis processes of indium-containing nanoparticles.

  15. Molecular and Atomic Gas in the Local Group Galaxy M33

    CERN Document Server

    Gratier, P; Rodriguez-Fernandez, N J; Schuster, K F; Kramer, C; Xilouris, E M; Tabatabaei, F S; Henkel, C; Corbelli, E; Israel, F; van der Werf, P P; Calzetti, D; Garcia-Burillo, S; Sievers, A; Combes, F; Wiklind, T; Brouillet, N; Herpin, F; Bontemps, S; Aalto, S; Koribalski, B; van der Tak, F; Wiedner, M C; Roellig, M; Mookerjea, B

    2010-01-01

    We present high resolution large scale observations of the molecular and atomic gas in the Local Group Galaxy M33. The observations were carried out using the HERA multibeam receiver at the 30m IRAM telescope in the CO(2-1) line achieving a resolution of 12" x 2.6km/s, enabling individual Giant Molecular Clouds (GMCs) to be resolved. The observed region is 650 square arcminutes mainly along the major axis and out to a radius of 8.5 kpc, and covers entirely the 2' x40' radial strip observed with the HIFI and PACS Spectrometers as part of the HERM33ES Herschel key program. The achieved sensitivity in main beam temperature is 20-50mK at 2.6km/s velocity resolution. The CO(2-1) luminosity of the observed region is 1.7+/-0.1x10^7 Kkm/s pc^2 and is estimated to be 2.8+/-0.3x10^7 Kkm/s pc^2 for the entire galaxy, corresponding to H_2 masses of 1.9x10^8 M_sun and 3.3x10^8 M_sun respectively (including He), calculated with a NH2/ICO twice the Galactic value due to the half-solar metallicity of M33. HI 21 cm VLA archiv...

  16. Molecular and Atomic Gas in the Large Magellanic Cloud - I. Conditions for CO Detection

    CERN Document Server

    Wong, T; Fukui, Y; Kawamura, A; Mizuno, N; Ott, J; Müller, E; Pineda, J L; Welty, D E; Kim, S; Mizuno, Y; Murai, M; Onishi, T

    2009-01-01

    We analyze the conditions for detection of CO(1-0) emission in the Large Magellanic Cloud (LMC), using the recently completed second NANTEN CO survey. In particular, we investigate correlations between CO integrated intensity and HI integrated intensity, peak brightness temperature, and line width at a resolution of 2.6' (~40 pc). We find that significant HI column density and peak brightness temperature are necessary but not sufficient conditions for CO detection, with many regions of strong HI emission not associated with molecular clouds. The large scatter in CO intensities for a given HI intensity persists even when averaging on scales of >200 pc, indicating that the scatter is not solely due to local conversion of HI into H_2 near GMCs. We focus on two possibilities to account for this scatter: either there exist spatial variations in the I(CO) to N(H_2) conversion factor, or a significant fraction of the atomic gas is not involved in molecular cloud formation. A weak tendency for CO emission to be suppr...

  17. Electrostatic trapping and in situ detection of Rydberg atoms above chip-based transmission lines

    CERN Document Server

    Lancuba, P

    2016-01-01

    Beams of helium atoms in Rydberg-Stark states with principal quantum number $n=48$ and electric dipole moments of 4600~D have been decelerated from a mean initial longitudinal speed of 2000~m/s to zero velocity in the laboratory-fixed frame-of-reference in the continuously moving electric traps of a transmission-line decelerator. In this process accelerations up to $-1.3\\times10^{7}$~m/s$^2$ were applied, and changes in kinetic energy of $\\Delta E_{\\mathrm{kin}}=1.3\\times10^{-20}$~J ($\\Delta E_{\\mathrm{kin}}/e = 83$~meV) per atom were achieved. Guided and decelerated atoms, and those confined in stationary electrostatic traps, were detected in situ by pulsed electric field ionisation. The results of numerical calculations of particle trajectories within the decelerator have been used to characterise the observed deceleration efficiencies, and aid in the interpretation of the experimental data.

  18. Electrostatic trapping and in situ detection of Rydberg atoms above chip-based transmission lines

    Science.gov (United States)

    Lancuba, P.; Hogan, S. D.

    2016-04-01

    Beams of helium atoms in Rydberg-Stark states with principal quantum number n = 48 and electric dipole moments of 4600 D have been decelerated from a mean initial longitudinal speed of 2000 m s-1 to zero velocity in the laboratory-fixed frame-of-reference in the continuously moving electric traps of a transmission-line decelerator. In this process accelerations up to -1.3× {10}7 m s-2 were applied, and changes in kinetic energy of {{Δ }}{E}{kin}=1.3× {10}-20 J ({{Δ }}{E}{kin}/e=83 meV) per atom were achieved. Guided and decelerated atoms, and those confined in stationary electrostatic traps, were detected in situ by pulsed electric field ionisation. The results of numerical calculations of particle trajectories within the decelerator have been used to characterise the observed deceleration efficiencies, and aid in the interpretation of the experimental data.

  19. Atomic and ionic spectrum lines below 2000A: hydrogen through argon

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, R.L.

    1982-10-01

    A critical tabulation of observed spectral lines below 2000 angstroms has been prepared from the published literature up to July 1978. It is intended principally as an aid to those physicists and astronomers who deal with the spectra of highly stripped atoms. This report includes the first 18 elements, from hydrogen (including deuterium) through argon. The tabulation is divided into two main sections: the spectrum lines by spectrum, and a finding list. The entries for each element give the ionization species, ground state term, and ionization potential, as well as the best values of vacuum wavelength, intensity, and classification. A list of the pertinent references is appended at the end.

  20. Neutral atomic absorption lines and far-UV extinction: Possible implications for depletions and grain parameters

    Science.gov (United States)

    Welty, Daniel E.

    1990-01-01

    Researchers examine nine lines of sight within the Galaxy and one in the Large Magellanic Cloud (LMC) for which data on both neutral atomic absorption lines (Snow 1984; White 1986; Welty, Hobbs, and York 1989) and far UV extinction (Bless and Savage 1972; Jenkins, Savage, and Spitzer 1986) are available, in order to test the assumption that variations in gamma/alpha will cancel in taking ratios of the ionization balance equation, and to try to determine to what extent that assumption has affected the aforementioned studies of depletions and grain properties.

  1. Detection of the 610 micron /492 GHz/ line of interstellar atomic carbon

    Science.gov (United States)

    Phillips, T. G.; Huggins, P. J.; Kuiper, T. B. H.; Miller, R. E.

    1980-01-01

    The ground-state transition of neutral atomic carbon, 3P1-3P0, has been detected in the interstellar medium at the frequency of 492.162 GHz determined in the laboratory by Saykally and Evenson (1980). The observations were made from the NASA Kuiper Airborne Observatory using an InSb heterodyne bolometer receiver. The line was detected as strong emission from eight molecular clouds and apparently provides a widely useful probe of the interstellar medium.

  2. Dispersion coefficients for the interaction of inert gas atoms with alkali and alkaline earth ions and alkali atoms with their singly ionized ions

    CERN Document Server

    Singh, Sukhjit; Sahoo, B K; Arora, Bindiya

    2016-01-01

    We report the dispersion coefficients for the interacting inert gas atoms with the alkali ions, alkaline earth ions and alkali atoms with their singly charged ions. We use our relativistic coupled-cluster method to determine dynamic dipole and quadrupole polarizabilities of the alkali atoms and singly ionized alkaline earth atoms, whereas a relativistic random phase approximation approach has been adopted to evaluate these quantities for the closed-shell configured inert gas atoms and the singly and doubly ionized alkali and alkaline earth atoms, respectively. Accuracies of these results are adjudged from the comparison of their static polarizability values with their respective experimental results. These polarizabilities are further compared with the other theoretical results. Reason for the improvement in the accuracies of our estimated dispersion coefficients than the data listed in [At. Data and Nucl. Data Tables 101, 58 (2015)] are discussed. Results for some of the atom-ion interacting systems were not...

  3. Distribution of Faint Atomic Gas in Hickson Compact Groups

    CERN Document Server

    Borthakur, Sanchayeeta; Verdes-Montenegro, Lourdes; Heckman, Timothy M; Zhu, Guangtun; Braatz, James A

    2015-01-01

    We present 21cm HI observations of four Hickson Compact Groups with evidence for a substantial intragroup medium using the Robert C. Byrd Green Bank Telescope (GBT). By mapping H I emission in a region of 25$^{\\prime}\\times$25$^{\\prime}$ (140-650 kpc) surrounding each HCG, these observations provide better estimates of HI masses. In particular, we detected 65% more \\HI than that detected in the Karl G. Jansky Very Large Array (VLA) imaging of HCG92. We also identify if the diffuse gas has the same spatial distribution as the high-surface brightness (HSB) HI features detected in the VLA maps of these groups by comparing the HI strengths between the observed and modeled masses based on VLA maps. We found that the HI observed with the GBT to have a similar spatial distribution as the HSB structures in HCGs 31 and 68. Conversely, the observed HI distributions in HCGs44 and 92 were extended and showed significant offsets from the modeled masses. Most of the faint gas in HCG44 lies to the Northeast-Southwest region...

  4. Structure of various K L1 x-ray satellite lines of heavy atoms

    Science.gov (United States)

    Polasik, Marek; Lewandowska-Robak, Maja

    2004-11-01

    Multiconfiguration Dirac-Fock calculations with the inclusion of the transverse (Breit) interaction and QED corrections have been carried out for Pd, Sn, Tb, Ta, Pb, and Th in order to obtain positions and intensities of various electric dipole, electric quadrupole, and magnetic dipole K x-ray diagram lines and of their KL1 satellites. Theoretically constructed stick spectra have been presented together with synthesized spectra (the sum of the Lorentzian natural line shapes) for each studied element. Taking into account the existence of an L -shell hole in the 2s or 2p subshell, the effect of additional L -shell ionization on the shapes and structure of the K x-ray spectra has been examined. It has been observed that generally with increasing atomic number Z the shapes of particular satellite line groups tend to become smoother and to differ less from the shapes of appropriate diagram lines. Relations between the values of energy shifts of various satellite lines for each element and the changes of these relations with Z have also been studied. Additionally, the relations between the intensities of different diagram lines for each element have been systematically analyzed, likewise the changes with Z of the role of particular diagram lines. This study can be helpful in reliable and quantitative interpretation of many experimental K x-ray spectra of Pd, Sn, Tb, Ta, Pb, and Th induced in collisions with various projectiles.

  5. Radiative Properties of Zeeman Components of Atomic Multiplets: Dependence of Line Intensities on the Magnetic Field

    Science.gov (United States)

    Ovsyannikov, V. D.; Chaplygin, E. V.

    2000-12-01

    Analytical expressions for the dependence of the intensity of Zeeman components of doublet lines on the magnetic field are obtained. Sharp changes of these function on passing from the anomalous Zeeman effect to the Paschen-Back effect lead to the disappearance of marginal lines and the equalization of intensities of remaining lines. In the region of the complete Paschen-Back effect, a strong influence on these dependences is produced by the dynamic atom-field interaction, which weakens the paramagnetic effect in the states with a positive magnetic quantum number m and enhances the effect in the states with a negative m. Simple analytical expressions are obtained that take into account the effect of the diamagnetic interaction on line intensities. The role of the diamagnetic interaction increases in Rydberg atomic states with a large spin-orbit splitting. For the states with m > 0, it can lead to the “diamagnetic reversal” of the Paschen-Back effect, i.e., the recovery of the anomalous Zeeman effect.

  6. Mg line formation in late-type stellar atmospheres: I. The model atom

    CERN Document Server

    Osorio, Y; Lind, K; Belyaev, A K; Spielfiedel, A; Guitou, M; Feautrier, N

    2015-01-01

    Mg is often traced in late-type stars using lines of neutral magnesium, which is expected to be subject to departures from LTE. The astrophysical importance of Mg as well as its relative simplicity from an atomic physics point of view, makes it a prime target and test bed for detailed ab initio non-LTE modelling in stellar atmospheres. For the low-lying states of Mg i, electron collision data were calculated using the R-matrix method. Calculations for collisional broadening by neutral hydrogen were also performed where data were missing. These calculations, together with data from the literature, were used to build a model atom. First, the modelling was tested by comparisons with observed spectra of benchmark stars with well-known parameters. Second, the spectral line behaviour and uncertainties were explored by extensive experiments in which sets of collisional data were changed or removed. The modelled spectra agree well with observed spectra. The line-to-line scatter in the derived abundances shows improve...

  7. Characteristics and Microstructure of a Hypereutectic Al-Si Alloy Powder by Ultrasonic Gas Atomization Process

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A hypereutectic Al-Si alloy powder was prepared by ultrasonic gas atomization process. The morphologies, microstructure and phase constituent of the alloy powder were studied. The results showed that powder of the alloy was very fine and its rnicrostructure was mainly consisted of Si crystals plus intermetallic compound Al9FeSi3, which were. very fine and uniformly distributed.

  8. The Use of an Air-Natural Gas Flame in Atomic Absorption.

    Science.gov (United States)

    Melucci, Robert C.

    1983-01-01

    Points out that excellent results are obtained using an air-natural gas flame in atomic absorption experiments rather than using an air-acetylene flame. Good results are obtained for alkali metals, copper, cadmium, and zinc but not for the alkaline earths since they form refractory oxides. (Author/JN)

  9. DIFFUSE ATOMIC AND MOLECULAR GAS IN THE INTERSTELLAR MEDIUM OF M82 TOWARD SN 2014J

    Energy Technology Data Exchange (ETDEWEB)

    Ritchey, Adam M. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Welty, Daniel E.; York, Donald G. [Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Ave., Chicago, IL 60637 (United States); Dahlstrom, Julie A., E-mail: aritchey@astro.washington.edu [Department of Physics and Astronomy, Carthage College, 2001 Alford Park Dr., Kenosha, WI 53140 (United States)

    2015-02-01

    We present a comprehensive analysis of interstellar absorption lines seen in moderately high resolution, high signal-to-noise ratio optical spectra of SN 2014J in M82. Our observations were acquired over the course of six nights, covering the period from ∼6 days before to ∼30 days after the supernova reached its maximum B-band brightness. We examine complex absorption from Na I, Ca II, K I, Ca I, CH{sup +}, CH, and CN, arising primarily from diffuse gas in the interstellar medium (ISM) of M82. We detect Li I absorption over a range in velocity consistent with that exhibited by the strongest Na I and K I components associated with M82; this is the first detection of interstellar Li in a galaxy outside of the Local Group. There are no significant temporal variations in the absorption-line profiles over the 37 days sampled by our observations. The relative abundances of the various interstellar species detected reveal that the ISM of M82 probed by SN 2014J consists of a mixture of diffuse atomic and molecular clouds characterized by a wide range of physical/environmental conditions. Decreasing N(Na I)/N(Ca II) ratios and increasing N(Ca I)/N(K I) ratios with increasing velocity are indicative of reduced depletion in the higher-velocity material. Significant component-to-component scatter in the N(Na I)/N(Ca II) and N(Ca I)/N(Ca II) ratios may be due to variations in the local ionization conditions. An apparent anti-correlation between the N(CH{sup +})/N(CH) and N(Ca I)/N(Ca II) ratios can be understood in terms of an opposite dependence on gas density and radiation field strength, while the overall high CH{sup +} abundance may be indicative of enhanced turbulence in the ISM of M82. The Li abundance also seems to be enhanced in M82, which supports the conclusions of recent gamma-ray emission studies that the cosmic-ray acceleration processes are greatly enhanced in this starburst galaxy.

  10. Diffuse Atomic and Molecular Gas in the Interstellar Medium of M82 toward SN 2014J

    Science.gov (United States)

    Ritchey, Adam M.; Welty, Daniel E.; Dahlstrom, Julie A.; York, Donald G.

    2015-02-01

    We present a comprehensive analysis of interstellar absorption lines seen in moderately high resolution, high signal-to-noise ratio optical spectra of SN 2014J in M82. Our observations were acquired over the course of six nights, covering the period from ~6 days before to ~30 days after the supernova reached its maximum B-band brightness. We examine complex absorption from Na I, Ca II, K I, Ca I, CH+, CH, and CN, arising primarily from diffuse gas in the interstellar medium (ISM) of M82. We detect Li I absorption over a range in velocity consistent with that exhibited by the strongest Na I and K I components associated with M82; this is the first detection of interstellar Li in a galaxy outside of the Local Group. There are no significant temporal variations in the absorption-line profiles over the 37 days sampled by our observations. The relative abundances of the various interstellar species detected reveal that the ISM of M82 probed by SN 2014J consists of a mixture of diffuse atomic and molecular clouds characterized by a wide range of physical/environmental conditions. Decreasing N(Na I)/N(Ca II) ratios and increasing N(Ca I)/N(K I) ratios with increasing velocity are indicative of reduced depletion in the higher-velocity material. Significant component-to-component scatter in the N(Na I)/N(Ca II) and N(Ca I)/N(Ca II) ratios may be due to variations in the local ionization conditions. An apparent anti-correlation between the N(CH+)/N(CH) and N(Ca I)/N(Ca II) ratios can be understood in terms of an opposite dependence on gas density and radiation field strength, while the overall high CH+ abundance may be indicative of enhanced turbulence in the ISM of M82. The Li abundance also seems to be enhanced in M82, which supports the conclusions of recent gamma-ray emission studies that the cosmic-ray acceleration processes are greatly enhanced in this starburst galaxy.

  11. Dipolar Rydberg-atom gas prepared by adiabatic passage through an avoided crossing

    CERN Document Server

    Wang, Limei; Zhang, Linjie; Li, Changyong; Yang, Yonggang; Zhao, Jianming; Raithel, Georg; Jia, Suotang

    2015-01-01

    The passage of cold cesium 49S$_{1/2}$ Rydberg atoms through an electric-field-induced multi-level avoided crossing with nearby hydrogen-like Rydberg levels is employed to prepare a cold, dipolar Rydberg atom gas. When the electric field is ramped through the avoided crossing on time scales on the order of 100~ns or slower, the 49S$_{1/2}$ population adiabatically transitions into high-\\emph{l} Rydberg Stark states. The adiabatic state transformation results in a cold gas of Rydberg atoms with large electric dipole moments. After a waiting time of about $1~\\mu$s and at sufficient atom density, the adiabatically transformed highly dipolar atoms become undetectable, enabling us to discern adiabatic from diabatic passage behavior through the avoided crossing. We attribute the state-selectivity to $m$-mixing collisions between the dipolar atoms. The data interpretation is supported by numerical simulations of the passage dynamics and of binary $m$-mixing collisions.

  12. Multi objective optimization of line pack management of gas pipeline system

    Science.gov (United States)

    Chebouba, A.

    2015-01-01

    This paper addresses the Line Pack Management of the "GZ1 Hassi R'mell-Arzew" gas pipeline. For a gas pipeline system, the decision-making on the gas line pack management scenarios usually involves a delicate balance between minimization of the fuel consumption in the compression stations and maximizing gas line pack. In order to select an acceptable Line Pack Management of Gas Pipeline scenario from these two angles for "GZ1 Hassi R'mell- Arzew" gas pipeline, the idea of multi-objective decision-making has been introduced. The first step in developing this approach is the derivation of a numerical method to analyze the flow through the pipeline under transient isothermal conditions. In this paper, the solver NSGA-II of the modeFRONTIER, coupled with a matlab program was used for solving the multi-objective problem.

  13. The relation between atomic gas and star formation rate densities in faint irregular galaxies

    CERN Document Server

    Roychowdhury, Sambit; Kaisin, Serafim S; Karachentsev, Igor D

    2014-01-01

    We use data for faint (M_B > -14.5) dwarf irregular galaxies drawn from the FIGGS survey to study the correlation between the atomic gas density (Sigma_gas,atomic) and star formation rate (Sigma_SFR) in the galaxies. The estimated gas phase metallicity of our sample galaxies is Z ~ 0.1 Z_sun. Understanding star formation in such molecule poor gas is of particular importance since it is likely to be of direct relevance to simulations of early galaxy formation. For about 20% (9/43) of our sample galaxies, we find that the HI distribution is significantly disturbed, with little correspondence between the optical and HI distributions. We exclude these galaxies from the comparison. We also exclude galaxies with very low star formation rates, for which stochastic effects make it difficult to estimate the true star formation rates. For the remaining galaxies we compute the Sigma_gas,atomic and Sigma_SFR averaged over the entire star forming disk of the galaxy. For these galaxies we find a nearly linear relation betw...

  14. Flow injection on-line solid phase extraction for ultra-trace lead screening with hydride generation atomic fluorescence spectrometry.

    Science.gov (United States)

    Wan, Zhuo; Xu, Zhangrun; Wang, Jianhua

    2006-01-01

    A flow injection (FI) on-line solid phase extraction (SPE) procedure for ultra-trace lead separation and preconcentration was developed, followed by hydride generation and atomic fluorescence spectrometric (AFS) detection. Lead is retained on an iminodiacetate chelating resin packed microcolumn, and is afterward eluted with 2.5% (v/v) hydrochloric acid to facilitate the hydride generation by reaction with alkaline tetrahydroborate solution with 1% (m/v) potassium ferricyanide as an oxidizing (or sensitizing) reagent. The hydride was separated from the reaction medium in the gas-liquid separator and swept into the atomizer for quantification. The chemical variables and the FI flow parameters were carefully optimized. With a sample loading volume of 4.8 ml, quantitative retention of lead was obtained, along with an enrichment factor of 11.3 and a sampling frequency of 50 h(-1). A detection limit of 4 ng l(-1), defined as 3 times the blank standard deviation (3 sigma), was achieved along with a RSD value of 1.6% at the 0.4 microg l(-1) level. The procedure was validated by determining lead contents in two certified reference materials, and its practical applicability was further demonstrated by analysing a variety of biological and environmental samples.

  15. Atoms

    Institute of Scientific and Technical Information of China (English)

    刘洪毓

    2007-01-01

    Atoms(原子)are all around us.They are something like the bricks (砖块)of which everything is made. The size of an atom is very,very small.In just one grain of salt are held millions of atoms. Atoms are very important.The way one object acts depends on what

  16. Low-excitation atomic gas around evolved stars II. ISO observations of O-rich nebulae

    NARCIS (Netherlands)

    Castro-Carrizo, A; Bujarrabal, [No Value; Fong, D; Meixner, M; Tielens, AGGM; Latter, WB; Barlow, MJ

    2001-01-01

    We have observed atomic fine-structure lines in the far-infrared (FIR) from 12 oxygen-rich evolved stars. The sample is composed of mostly proto-planetary nebulae (PPNe) and some planetary nebulae (PNe) and asymptotic giant branch (AGB) stars. ISO LWS and SWS observations of [O I]. [C II], [N II], [

  17. Extended Carbon Line Emission in the Galaxy: Searching for Dark Molecular Gas along the G328 Sightline

    CERN Document Server

    Burton, Michael G; Braiding, Catherine; Freeman, Matthew; Kulesa, Craig; Wolfire, Mark G; Hollenbach, David J; Rowell, Gavin; Lau, James

    2015-01-01

    We present spectral data cubes of the [CI] 809GHz, 12CO 115GHz, 13CO 110GHz and HI 1.4GHz line emission from an 1 square degree region along the l = 328{\\deg} (G328) sightline in the Galactic Plane. Emission arises principally from gas in three spiral arm crossings along the sight line. The distribution of the emission in the CO and [CI] lines is found to be similar, with the [CI] slightly more extended, and both are enveloped in extensive HI. Spectral line ratios per voxel in the data cubes are found to be similar across the entire extent of the Galaxy. However, towards the edges of the molecular clouds the [CI]/13CO and 12CO/13CO line ratios rise by ~50%, and the [CI]/HI ratio falls by ~10$%. We attribute this to these sightlines passing predominantly through the surfaces of photodissociation regions (PDRs), where the carbon is found mainly as C or C+, while the H2 is mostly molecular, and the proportion of atomic gas also increases. We undertake modelling of the PDR emission from low density molecular clou...

  18. Resolved atomic lines reveal outflows in two ultraluminous X-ray sources

    CERN Document Server

    Pinto, Ciro; Fabian, Andrew C

    2016-01-01

    Ultraluminous X-ray sources are extragalactic, off-nucleus, point sources in galaxies with an X-ray luminosity above 3x10^39 erg/s, thought to be powered by accretion onto a compact object. Possible explanations include accretion onto neutron stars with strong magnetic fields, stellar-mass black holes ( 5 sigma, and blueshifted (~0.2c) absorption lines (5 sigma) in the high-resolution X-ray spectrum of the ultraluminous X-ray source NGC 1313 X-1. In a similar source, NGC 5408 X-1, we also detect emission lines at rest and blueshifted absorption. The blueshifted absorption lines must occur in a fast outflowing gas, whereas the emission lines originate in slow-moving gas around the source. We conclude that the compact object is surrounded by powerful winds with an outflow velocity of about 0.2c as predicted by models of accreting supermassive black holes and hyper-accreting stellar mass black holes.

  19. proEQUIB: IDL/GDL library for atomic level populations and line emissivities in statistical equilibrium

    Science.gov (United States)

    Danehkar, Ashkbiz

    2016-11-01

    The proEQUIB library calculates atomic level populations and line emissivities in statistical equilibrium in multi-level atoms for different physical conditions of stratified layers in a nebula where chemical elements are ionized. It includes an Interactive Data Language (IDL)/GNU Data Language (GDL) implementation of the Fortran code EQUIB (ascl:1603.005).

  20. Evanescent-wave trapping and evaporative cooling of an atomic gas near two-dimensionality

    CERN Document Server

    Hammes, M; Engeser, B; Nägerl, H C; Grimm, R

    2003-01-01

    A dense gas of cesium atoms at the crossover to two-dimensionality is prepared in a highly anisotropic surface trap that is realized with two evanescent light waves. Temperatures as low as 100nK are reached with 20.000 atoms at a phase-space density close to 0.1. The lowest quantum state in the tightly confined direction is populated by more than 60%. The system offers intriguing prospects for future experiments on degenerate quantum gases in two dimensions.

  1. Mapping the Two-Component Atomic Fermi Gas to the Nuclear Shell-Model

    DEFF Research Database (Denmark)

    Özen, C.; Zinner, Nikolaj Thomas

    2014-01-01

    of the external potential becomes important. A system of two-species fermionic cold atoms with an attractive zero-range interaction is analogous to a simple model of nucleus in which neutrons and protons interact only through a residual pairing interaction. In this article, we discuss how the problem of a two......-component atomic fermi gas in a tight external trap can be mapped to the nuclear shell model so that readily available many-body techniques in nuclear physics, such as the Shell Model Monte Carlo (SMMC) method, can be directly applied to the study of these systems. We demonstrate an application of the SMMC method...

  2. Effect of Brownian Coagulation on the Liquid-liquid Decomposition in Gas-atomized Alloy Drops

    Institute of Scientific and Technical Information of China (English)

    Jiuzhou ZHAO; Lingling GAO; Jie HE; L.Ratke

    2006-01-01

    Modeling and simulation have been carried out for Al-Pb alloys to investigate the Brownian coagulation effect on the microstructure development in a gas-atomized drop during the liquid-liquid decomposition.The results indicate that Brownian coagulation has a weak effect on the nucleation and a relatively strong effect on coarsening the minority phase droplets. The influence of Brownian coagulation on the liquid-liquid decomposition decreases with the increase in the diameter (or the decrease in the cooling rate) of the atomized drop.

  3. Chemical reactivity of the compressed noble gas atoms and their reactivity dynamics during collisions with protons

    Indian Academy of Sciences (India)

    P K Chattaraj; B Maiti; U Sarkar

    2003-06-01

    Attempts are made to gain insights into the effect of confinement of noble gas atoms on their various reactivity indices. Systems become harder, less polarizable and difficult to excite as the compression increases. Ionization also causes similar effects. A quantum fluid density functional technique is adopted in order to study the dynamics of reactivity parameters during a collision between protons and He atoms in different electronic states for various projectile velocities and impact parameters. Dynamical variants of the principles of maximum hardness, minimum polarizability and maximum entropy are found to be operative.

  4. The complexity of the coronal line region in AGNs: Gas-jet interactions and outflows revealed by NIR spectroscopy

    Science.gov (United States)

    Rodríguez-Ardila, Alberto; Prieto, Almudena; Mazzalay, Ximena

    2016-08-01

    Apart from the classical broad line region (BLR) at small core distances, and the extended classical narrow-line region (NLR), a subset of active galactic nuclei (AGN) show, in their spectra, lines from very highly ionised atoms, known as Coronal lines (CLs). The precise nature and origin of these CLs remain uncertain. Advances on this matter include the determination of the size and morphology of the CLR by means of optical HST and ground-based AO imaging/spectroscopy in a few AGNs. The results indicate CLRs with sizes varying from compact (~30 pc) to extended (~200 pc) emission and aligned preferentially with the direction of the lower ionisation cones seen in these sources. In this talk, we present results of a pioneering work aimed at studying the CLR in the near-infrared region on a selected sample of nearby AGNs. The excellent angular resolution of the data allowed us to resolve and map the extension of the coronal line gas and compare it to that emitting low- and mid-ionization lines. In most cases, the very good match between the radio emission and the CLR suggest that at least part of the high-ionization gas is jet-driven. Results from photoionization models where the central engine is the only source of energy input strongly fail at reproducing the observed line ratios, mainly at distances larger than 60 pc from the centre. We discuss here other processes that should be at work to enhance this energetic emission and suggest that the presence of coronal lines in AGNs is an unambiguous signature of feedback processes in these sources.

  5. Early Science with the Large Millimeter Telescope: COOL BUDHIES I - a pilot study of molecular and atomic gas at z ≃ 0.2

    Science.gov (United States)

    Cybulski, Ryan; Yun, Min S.; Erickson, Neal; De la Luz, Victor; Narayanan, Gopal; Montaña, Alfredo; Sánchez, David; Zavala, Jorge A.; Zeballos, Milagros; Chung, Aeree; Fernández, Ximena; van Gorkom, Jacqueline; Haines, Chris P.; Jaffé, Yara L.; Montero-Castaño, María; Poggianti, Bianca M.; Verheijen, Marc A. W.; Yoon, Hyein; Deshev, Boris Z.; Harrington, Kevin; Hughes, David H.; Morrison, Glenn E.; Schloerb, F. Peter; Velazquez, Miguel

    2016-07-01

    An understanding of the mass build-up in galaxies over time necessitates tracing the evolution of cold gas (molecular and atomic) in galaxies. To that end, we have conducted a pilot study called CO Observations with the LMT of the Blind Ultra-Deep H I Environment Survey (COOL BUDHIES). We have observed 23 galaxies in and around the two clusters Abell 2192 (z = 0.188) and Abell 963 (z = 0.206), where 12 are cluster members and 11 are slightly in the foreground or background, using about 28 total hours on the Redshift Search Receiver on the Large Millimeter Telescope (LMT) to measure the 12CO J = 1 → 0 emission line and obtain molecular gas masses. These new observations provide a unique opportunity to probe both the molecular and atomic components of galaxies as a function of environment beyond the local Universe. For our sample of 23 galaxies, nine have reliable detections (S/N ≥ 3.6) of the 12CO line, and another six have marginal detections (2.0 < S/N < 3.6). For the remaining eight targets we can place upper limits on molecular gas masses roughly between 109 and 1010 M⊙. Comparing our results to other studies of molecular gas, we find that our sample is significantly more abundant in molecular gas overall, when compared to the stellar and the atomic gas component, and our median molecular gas fraction lies about 1σ above the upper limits of proposed redshift evolution in earlier studies. We discuss possible reasons for this discrepancy, with the most likely conclusion being target selection and Eddington bias.

  6. Understanding Atomic Structure: Is There a More Direct and Compelling Connection between Atomic Line Spectra and the Quantization of an Atom's Energy?

    Science.gov (United States)

    Rittenhouse, Robert C.

    2015-01-01

    The "atoms first" philosophy, adopted by a growing number of General Chemistry textbook authors, places greater emphasis on atomic structure as a key to a deeper understanding of the field of chemistry. A pivotal concept needed to understand the behavior of atoms is the restriction of an atom's energy to specific allowed values. However,…

  7. Surveys of the Milky Way and Magellanic System in the λ21-cm line of atomic hydrogen

    Directory of Open Access Journals (Sweden)

    Dickey J.M.

    2012-02-01

    Full Text Available In the next three years, surveys of the Northern and Southern skies using focal plane arrays on aperture synthesis radio telescopes will lead to a breakthrough in our knowledge of the warm and cool atomic phases of the interstellar medium and their relationship with the diffuse molecular gas. The sensitivity and resolution of these surveys will give an order of magnitude or more improvement over existing interstellar medium data. The GASKAP (South and GAMES (North projects together constitute a complete survey of the Milky Way plane and the Magellanic Clouds and Stream in both emission and absorption in the H I 21-cm line and the OH 18-cm lines. The overall goal of this project is to understand the mechanism of galaxy evolution, through a detailed tracing of the astrophysical processes that drive the cycle of star formation in very different environments. Comparison of 21-cm emission and absorption highlights the transition from the warm, diffuse medium to cool clouds. Tracing turbulence in the Magellanic Stream shows how extra-galactic gas makes the difficult passage through the halo to replenish the disk. Finally, high resolution images of OH masers trace outflows from evolved stars that enrich the medium with heavy elements. To understand how the Milky Way was assembled and how it has evolved since, the speed and efficiency of these processes must be measured, as functions of Galactic radius and height above the plane. Observations of similar processes in the Magellanic Clouds show how differently they might have worked in conditions typical of the early universe.

  8. On-line non-contact gas analysis

    DEFF Research Database (Denmark)

    Fateev, Alexander; Clausen, Sønnik

    Non-intrusive and fast measurements of the gas temperature, NO and other gas concentrations at elevated temperatures in boilers, engines and flames are of the great interest. The optical properties of the gases must be known in a spectral range and temperature level of interest. High-resolution I...... composition in the near-burner field with co-firing of biomass and coal, and NO measurements in a large diesel engine....

  9. A far-infrared molecular and atomic line survey of the Orion KL region

    CERN Document Server

    Lerate, M R; Swinyard, B M; Goicoechea, J R; Cernicharo, J; Grundy, T W; Lim, T L; Polehampton, E T; Baluteau, J P; Viti, S; Yates, J

    2006-01-01

    We have carried out a high spectral resolution line survey towards the Orion Kleinmann-Low (KL) cluster from 44-188 um. The observations were taken with the Long Wavelength Spectrometer (LWS) in Fabry-Perot mode, on board the Infrared Space Observatory (ISO). A total of 152 lines are clearly detected and a further 34 features are present as possible detections. The spectrum is dominated by the molecular species H2O, OH and CO, along with [OI] and [CII] lines from PDR or shocked gas and [OIII], [NIII] lines from the foreground M42 HII region. Several isotopic species, as well as NH3, are also detected. HDO and H3O+ are tentatively detected for the first time in the far-infrared range towards Orion-KL. A basic analysis of the line observations is carried out, by comparing with previous measurements and published models and deriving rotational temperatures and column densities in the case of the molecular species. The complexity of the region requires more sophisticated models for the interpretation of all the l...

  10. Model for Atomic Oxygen Visible Line Emissions in Comet C/1995 O1 Hale-Bopp

    CERN Document Server

    Raghuram, Susarla

    2012-01-01

    We have recently developed a coupled chemistry-emission model for the green and red-doublet emissions of atomic oxygen on comet Hyakutake. In the present work we applied our model to comet Hale-Bopp, which had an order of magnitude higher H2O production rate than comet Hyakutake, to evaluate the photochemistry associated with the production and loss of O(1S) and O(1D) atoms and emission processes of green and red-doublet lines. We present the wavelength-dependent photo-attenuation rates for different photodissociation processes forming O(1S) and O(1D). The calculated radiative efficiency profiles of O(1S) and O(1D) atoms show that in comet Hale-Bopp the green and red-doublet emissions are emitted mostly above radial distances of 10^3 and 10^4 km, respectively. The model calculated [OI] 6300 A emission surface brightness and average intensity over the Fabry-P{\\'e}rot spectrometer field of view are consistent with the observation of Morgenthaler et al. (2001), while the intensity ratio of green to red-doublet e...

  11. Coherent population trapping resonances at lower atomic levels of Doppler broadened optical lines

    Energy Technology Data Exchange (ETDEWEB)

    Şahin, E; Hamid, R; Çelik, M [National Metrology Institute of Turkey, Gebze, Kocaeli (Turkey); Özen, G [Istanbul Technical University, Faculty of Science and Letters, Engineering Physics Department Maslak, Istanbul (Turkey); Izmailov, A Ch [Institute of Physics, Azerbaijan National Academy of Sciences, H. Javid av. 33, Baku, Az-1143 (Azerbaijan)

    2014-11-30

    We have detected and analysed narrow high-contrast coherent population trapping (CPT) resonances, which are induced in absorption of a weak monochromatic probe light beam by counterpropagating two-frequency pump radiation in a cell with rarefied caesium vapour. The experimental investigations have been performed by the example of nonclosed three level Λ-systems formed by spectral components of the D{sub 2} line of caesium atoms. The applied method allows one to analyse features of the CPT phenomenon directly at a given low long-lived level of the selected Λ-system even in sufficiently complicated spectra of atomic gases with large Doppler broadening. We have established that CPT resonances in transmission of the probe beam exhibit not only a higher contrast but also a much lesser width in comparison with well- known CPT resonances in transmission of the corresponding two-frequency pump radiation. The results obtained can be used in selective photophysics, photochemistry and ultra-high resolution atomic (molecular) spectroscopy. (laser applications and other topics in quantum electronics)

  12. Phase diagrams for an ideal gas mixture of fermionic atoms and bosonic molecules

    DEFF Research Database (Denmark)

    Williams, J. E.; Nygaard, Nicolai; Clark, C. W.

    2004-01-01

    We calculate the phase diagrams for a harmonically trapped ideal gas mixture of fermionic atoms and bosonic molecules in chemical and thermal equilibrium, where the internal energy of the molecules can be adjusted relative to that of the atoms by use of a tunable Feshbach resonance. We plot...... the molecule fraction and the fraction of Bose-condensed molecules as functions of the temperature and internal molecular energy. We show the paths traversed in the phase diagrams when the molecular energy is varied either suddenly or adiabatically. Our model calculation helps to interpret the adiabatic phase...... diagrams obtained in recent experiments on the Bose-Einstein condensation to Bardeen-Cooper-Schrieffer crossover, in which the condensate fraction is plotted as a function of the initial temperature of the Fermi gas measured before a sweep of the magnetic field through the resonance region....

  13. Dimensionality and Finite Number Effect on BCS Transition of Atomic Fermi Gas

    Institute of Scientific and Technical Information of China (English)

    CUI Hai-Tao; WANG Lin-Cheng; YI Xue-Xi

    2005-01-01

    The effect of finite number and dimensionality has been discussed in this paper. The finite number effect has a negative correction to final temperature for 2D or 3D atomic Fermi gases. The changing of final temperature obtained by scanning from BEC region to BCS region are 10% or so with N ≤ 103 and can be negligible when N > 103.However, in 1D atomic Fermi gas, the effect gives a positive correction which greatly changes the final temperature in Fermi gas. This behavior is completely opposed to the 2D and 3D cases and a proper explanation is still to be found.Dimensionality also has a positive correction, in which the more tightly trapping, the higher final temperature one gets with the same particle number. A discussion is also presented.

  14. Far-field resonance fluorescence from a dipole-interacting laser-driven cold atomic gas

    Science.gov (United States)

    Jones, Ryan; Saint, Reece; Olmos, Beatriz

    2017-01-01

    We analyze the temporal response of the fluorescence light that is emitted from a dense gas of cold atoms driven by a laser. When the average interatomic distance is comparable to the wavelength of the photons scattered by the atoms, the system exhibits strong dipolar interactions and collective dissipation. We solve the exact dynamics of small systems with different geometries and show how these collective features are manifest in the scattered light properties such as the photon emission rate, the power spectrum and the second-order correlation function. By calculating these quantities beyond the weak (linear) driving limit, we make progress in understanding the signatures of collective behavior in these many-body systems. Furthermore, we shed light on the role of disorder and averaging on the resonance fluorescence, of direct relevance for recent experimental efforts that aim at the exploration of many-body effects in dipole-dipole interacting gases of atoms.

  15. Gas lines from the 5-Myr old optically thin disk around HD141569A. Herschel observations and modeling

    CERN Document Server

    Thi, Wing-Fai; Pantin, Eric; Augereau, Jean-Charles; Meeus, Gwendolyn; Menard, Francois; Martin-Zaïdi, Claire; Woitke, Peter; Riviere-Marichalar, Pablo; Kamp, Inga; Carmona, Andres; Sandell, Goran; Eiroa, Carlos; Dent, Williams; Montesinos, Benjamin; Aresu, Giambattista; Meijerink, Rowin; Spaans, Marco; White, Glenn; Ardila, David; Lebreton, Jeremy; Mendigutia, Ignacio; Brittain, Sean

    2013-01-01

    At the distance of 99-116 pc, HD141569A is one of the nearest HerbigAe stars that is surrounded by a tenuous disk, probably in transition between a massive primordial disk and a debris disk. We observed the fine-structure lines of OI at 63 and 145 micron and the CII line at 157 micron with the PACS instrument onboard the Herschel Space Telescope as part of the open-time large programme GASPS. We complemented the atomic line observations with archival Spitzer spectroscopic and photometric continuum data, a ground-based VLT-VISIR image at 8.6 micron, and 12CO fundamental ro-vibrational and pure rotational J=3-2 observations. We simultaneously modeled the continuum emission and the line fluxes with the Monte Carlo radiative transfer code MCFOST and the thermo-chemical code ProDiMo to derive the disk gas- and dust properties assuming no dust settling. The models suggest that the oxygen lines are emitted from the inner disk around HD141569A, whereas the [CII] line emission is more extended. The CO submillimeter fl...

  16. Moment of inertia of a trapped superfluid gas of atomic fermions

    OpenAIRE

    Farine, M.; Schuck, Peter; Viñas Gausí, Xavier

    2000-01-01

    The moment of inertia of a trapped superfluid gas of atomic Fermions (6Li) is calculated as a function of two system parameters: temperature and deformation of the trap. For moderate deformations at zero temperature the moment of inertia takes on the irrotational flow value. Only for T very close to the critical temperature rigid rotation is attained. For very strong trap deformations the moment of inertia approaches its rigid body value even in the superfluid state. It is proposed that futur...

  17. Evolution of the atomic and molecular gas content of galaxies in dark matter haloes

    CERN Document Server

    Popping, G; Peeples, M S

    2014-01-01

    We present a semi-empirical model to infer the atomic and molecular hydrogen content of galaxies as a function of halo mass and time. Our model combines the SFR-halo mass-redshift relation (constrained by galaxy abundances) with inverted SFR-surface density relations to infer galaxy H I and H2 masses. We present gas scaling relations, gas fractions, and mass functions from z = 0 to z = 3 and the gas properties of galaxies as a function of their host halo masses. Predictions of our work include: 1) there is a ~ 0.2 dex decrease in the H I mass of galaxies as a function of their stellar mass since z = 1.5, whereas the H2 mass of galaxies decreases by > 1 dex over the same period. 2) galaxy cold gas fractions and H2 fractions decrease with increasing stellar mass and time. Galaxies with M* > 10^10 Msun are dominated by their stellar content at z < 1, whereas less-massive galaxies only reach these gas fractions at z = 0. We find the strongest evolution in relative gas content at z < 1.5. 3) the SFR to gas m...

  18. Plasma Sprayed Pour Tubes and Other Melt Handling Components for Use in Gas Atomization

    Energy Technology Data Exchange (ETDEWEB)

    Byrd, David; Rieken, Joel; Heidloff, Andy; Besser, Matthew; Anderson, Iver

    2011-04-01

    Ames Laboratory has successfully used plasma sprayed ceramic components made from yttria stabilized zirconia as melt pouring tubes for gas atomization for many years. These tubes have proven to be strong, thermal shock resistant and versatile. Various configurations are possible both internally and externally. Accurate dimensions are achieved internally with a machined fugitive graphite mandrel and externally by diamond grinding. The previous study of the effect of spray parameters on density was extended to determine the effect of the resulting density on the thermal shock characteristics on down-quenching and up-quenching. Encouraging results also prompted investigation of the use of plasma spraying as a method to construct a melt pour exit stopper that is mechanically robust, thermal shock resistant, and not susceptible to attack by reactive melt additions. The Ames Laboratory operates two close-coupled high pressure gas atomizers. These two atomizers are designed to produce fine and coarse spherical metal powders (5{mu} to 500{mu} diameter) of many different metals and alloys. The systems vary in size, but generally the smaller atomizer can produce up to 5 kg of powder whereas the larger can produce up to 25 kg depending on the charge form and density. In order to make powders of such varying compositions, it is necessary to have melt systems capable of heating and containing the liquid charge to the desired superheat temperature prior to pouring through the atomization nozzle. For some metals and alloys this is not a problem; however for some more reactive and/or high melting materials this can pose unique challenges. Figure 1 is a schematic that illustrates the atomization system and its components.

  19. Controlling residual hydrogen gas in mass spectra during pulsed laser atom probe tomography.

    Science.gov (United States)

    Kolli, R Prakash

    2017-01-01

    Residual hydrogen (H2) gas in the analysis chamber of an atom probe instrument limits the ability to measure H concentration in metals and alloys. Measuring H concentration would permit quantification of important physical phenomena, such as hydrogen embrittlement, corrosion, hydrogen trapping, and grain boundary segregation. Increased insight into the behavior of residual H2 gas on the specimen tip surface in atom probe instruments could help reduce these limitations. The influence of user-selected experimental parameters on the field adsorption and desorption of residual H2 gas on nominally pure copper (Cu) was studied during ultraviolet pulsed laser atom probe tomography. The results indicate that the total residual hydrogen concentration, HTOT, in the mass spectra exhibits a generally decreasing trend with increasing laser pulse energy and increasing laser pulse frequency. Second-order interaction effects are also important. The pulse energy has the greatest influence on the quantity HTOT, which is consistently less than 0.1 at.% at a value of 80 pJ.

  20. Measurement of atomic Stark parameters of many Mn I and Fe I spectral lines using GMAW process

    Energy Technology Data Exchange (ETDEWEB)

    Zielinska, S; Pellerin, S; Valensi, F [GREMI, Universite d' Orleans (Site de Bourges)/CNRS, BP 4043, 18028 Bourges cedex (France); Dzierzega, K; Musiol, K [Marian Smoluchowski Institute of Physics, Jagellonian University, Krakow (Poland); Briand, F, E-mail: sylwia.zielinska@airliquide.co, E-mail: stephane.pellerin@univ-orleans.f, E-mail: krzycho@netmail.if.uj.edu.p, E-mail: flavien.valensi@laplace.univ-tsle.f, E-mail: ufmusiol@cyf-kr.edu.p, E-mail: francis.briand@airliquide.co [CTAS-Air Liquide Welding, Saint Ouen l' Aunone, 95315 Cergy-Pontoise cedex (France)

    2010-11-03

    The particular character of the welding arc working in pure argon, whose emission spectrum consists of many spectral lines strongly broadened by the Stark effect, has allowed measurement, sometimes for the first time, of the Stark parameters of 15 Mn I and 10 Fe I atomic spectral lines, and determination of the dependence on temperature of normalized Stark broadening in N{sub e} = 10{sup 23} m{sup -3} of the 542.4 nm atomic iron line. These results show that special properties of the MIG plasma may be useful in this domain because composition of the wire-electrode may be easily adapted to the needs of an experiment.

  1. The RESOLVE Survey Atomic Gas Census and Environmental Influences on Galaxy Gas Reservoirs

    Science.gov (United States)

    Stark, David V.; Kannappan, Sheila J.; Eckert, Kathleen D.; Florez, Jonathan; Hall, Kirsten R.; Watson, Linda C.; Hoversten, Erik A.; Burchett, Joseph N.; Guynn, David T.; Baker, Ashley D.; Moffett, Amanda J.; Berlind, Andreas A.; Norris, Mark A.; Haynes, Martha P.; Giovanelli, Riccardo; Leroy, Adam K.; Pisano, D. J.; Wei, Lisa H.; Gonzalez, Roberto E.; Calderon, Victor F.

    2016-12-01

    We present the H i mass inventory for the REsolved Spectroscopy Of a Local VolumE (RESOLVE) survey, a volume-limited, multi-wavelength census of >1500 z = 0 galaxies spanning diverse environments and complete in baryonic mass down to dwarfs of ˜109 {M}⊙ . This first 21 cm data release provides robust detections or strong upper limits (1.4M H i dark matter halo mass M h, central/satellite designation, relative mass density of the cosmic web, and distance to the nearest massive group. We find that at fixed M *, satellites have decreasing G/S with increasing M h starting clearly at M h ˜ 1012 {M}⊙ , suggesting the presence of starvation and/or stripping mechanisms associated with halo gas heating in intermediate-mass groups. The analogous relationship for centrals is uncertain because halo abundance matching builds in relationships between central G/S, stellar mass, and halo mass, which depend on the integrated group property used as a proxy for halo mass (stellar or baryonic mass). On larger scales G/S trends are less sensitive to the abundance matching method. At fixed M h ≤ 1012 {M}⊙ , the fraction of gas-poor centrals increases with large-scale structure density. In overdense regions, we identify a rare population of gas-poor centrals in low-mass (M h 1012 {M}⊙ ) halos, suggesting that gas stripping and/or starvation may be induced by interactions with larger halos or the surrounding cosmic web. We find that the detailed relationship between G/S and environment varies when we examine different subvolumes of RESOLVE independently, which we suggest may be a signature of assembly bias.

  2. The Buffer Gas Beam: An Intense, Cold, and Slow Source for Atoms and Molecules

    CERN Document Server

    Hutzler, Nicholas R; Doyle, John M

    2011-01-01

    Beams of atoms and molecules are stalwart tools for spectroscopy and studies of collisional processes. The supersonic expansion technique can create cold beams of many species of atoms and molecules. However, the resulting beam is typically moving at a speed of 300-600 m/s in the lab frame, and for a large class of species has insufficient flux (i.e. brightness) for important applications. In contrast, buffer gas beams can be a superior method in many cases, producing cold and relatively slow molecules in the lab frame with high brightness and great versatility. There are basic differences between supersonic and buffer gas cooled beams regarding particular technological advantages and constraints. At present, it is clear that not all of the possible variations on the buffer gas method have been studied. In this review, we will present a survey of the current state of the art in buffer gas beams, and explore some of the possible future directions that these new methods might take.

  3. Numerical simulation of flow in Hartmann resonance tube and flow in ultrasonic gas atomizer

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The gas flow in the Hartmann resonance tube is numerically investigated by the finite volume method based on the Roe solver. The oscillation of the flow is studied with the presence of a needle actuator set along the nozzle axis. Numerical results agree well with the theoretical and experimental results available. Numerical results indicate that the resonance mode of the resonance tube will switch by means of removing or adding the actuator. The gas flow in the ultrasonic gas atomization (USGA) nozzle is also studied by the same numerical methods. Oscillation caused by the Hartmann resonance tube structure, coupled with a secondary resonator, in the USGA nozzle isinvestigated. Effects of the variation of parameters on the iscillation are studied. The mechanism of the transition of subsonic flow to supersonic flow in the USGA nozzle is also discussed based on numerical results.

  4. On-line sample treatment - Capillary gas chromatography

    NARCIS (Netherlands)

    Goosens, EC; de Jong, D; de Jong, GJ; Brinkman, UAT

    1998-01-01

    Sample pretreatment is often the bottleneck of a trace level analytical procedure. In order to increase performance, increasing attention is therefore being devoted to combining sample pretreatment on-line with the separation technique that has to be used. In the present review, a variety of procedu

  5. Widom line for the liquid-gas transition in Lennard-Jones system.

    Science.gov (United States)

    Brazhkin, V V; Fomin, Yu D; Lyapin, A G; Ryzhov, V N; Tsiok, E N

    2011-12-08

    The locus of extrema (ridges) for heat capacity, thermal expansion coefficient, compressibility, and density fluctuations for model particle systems with Lennard-Jones (LJ) potential in the supercritical region have been obtained. It was found that the ridges for different thermodynamic values virtually merge into a single Widom line at T Widom line for a liquid-gas transition.

  6. Review Applications to Prevent Corrosion Reducing Gas Pipe Line

    Directory of Open Access Journals (Sweden)

    Mehrdad Setoudeh

    2012-10-01

    Full Text Available Corrosion is one of the major problems in the oil and gas industry is one that automatically allocates huge sums annually. Including ways to reduce corrosion of corrosion inhibitors is. Inhibiting substance that low amount is added to the system to slow or stop the chemical reaction does. When inhibitors of corrosion medium are added, the speed of corrosion decreases to zero takes. For the first time a deterrent mineral called arsenate sodium for inhibition steels carbon in oil wells was used to corrosion of CO2 prevented, but due to low yield was not satisfactory and therefore the other inhibitors were used. In the years 1945 to 1950 properties, excellent composition polar chain long was discovered. The discovery process of experiments related to organic inhibitors used in wells and pipes and oil Garza changed. This article examines the use of inhibitors to reduce corrosion in gas wells deals.

  7. Nonlinear longitudinal oscillations of fuel in rockets feed lines with gas-liquid damper

    Science.gov (United States)

    Avramov, K. V.; Filipkovsky, S.; Tonkonogenko, A. M.; Klimenko, D. V.

    2016-03-01

    The mathematical model of the fuel oscillations in the rockets feed lines with gas-liquid dampers is derived. The nonlinear model of the gas-liquid damper is suggested. The vibrations of fuel in the feed lines with the gas-liquid dampers are considered nonlinear. The weighted residual method is applied to obtain the finite degrees of freedom nonlinear model of the fuel oscillations. Shaw-Pierre nonlinear normal modes are applied to analyze free vibrations. The forced oscillations of the fuel at the principle resonances are analyzed. The stability of the forced oscillations is investigated. The results of the forced vibrations analysis are shown on the frequency responses.

  8. Detection of copper in water using on-line plasma-excited atomic absorption spectroscopy (AAS).

    Science.gov (United States)

    Porento, Mika; Sutinen, Veijo; Julku, Timo; Oikari, Risto

    2011-06-01

    A measurement method and apparatus was developed to measure continuously toxic metal compounds in industrial water samples. The method was demonstrated by using copper as a sample metal. Water was injected into the sample line and subsequently into a nitrogen plasma jet, in which the samples comprising the metal compound dissolved in water were decomposed. The transmitted monochromatic light was detected and the absorbance caused by copper atoms was measured. The absorbance and metal concentration were used to calculate sensitivity and detection limits for the studied metal. The sensitivity, limit of detection, and quantification for copper were 0.45 ± 0.02, 0.25 ± 0.01, and 0.85 ± 0.04 ppm, respectively.

  9. Metallicity measurements using atomic lines in M and K dwarf stars

    CERN Document Server

    Woolf, V M; Woolf, Vincent M.; Wallerstein, George

    2004-01-01

    We report the first survey of chemical abundances in M and K dwarf stars using atomic absorption lines in high resolution spectra. We have measured Fe and Ti abundances in 35 M and K dwarf stars using equivalent widths measured from (lambda / Delta lambda) = 33,000 spectra. Our analysis takes advantage of recent improvements in model atmospheres of low-temperature dwarf stars. The stars have temperatures between 3300 and 4700 K, with most cooler than 4100 K. They cover an iron abundance range of -2.44 < [Fe/H] < +0.16. Our measurements show [Ti/Fe] decreasing with increasing [Fe/H], a trend similar to that measured for warmer stars where abundance analysis techniques have been tested more thoroughly. This study is a step toward the observational calibration of procedures to estimate the metallicity of low-mass dwarf stars using photometric and low-resolution spectral indices.

  10. Exploring the optical contrast effect in strong atomic lines for exoplanets transiting active stars

    Science.gov (United States)

    Cauley, Paul W.; Redfield, Seth

    2017-01-01

    Transmission spectroscopy is a powerful tool for detecting and characterizing planetary atmospheres. Non-photospheric features on the stellar disk, however, can contaminate the planetary signal: during transit the observed spectrum is weighted towards the features not currently being occulted by the planet. This contrast effect can mimic absorption in the planetary atmosphere for strong atomic lines such as Na I, Ca II, and the hydrogen Balmer lines. While the contrast effect is negligible for quiet stars, contributions to the transmission signal from active stellar surfaces can produce ~1% changes in the line core. It is therefore critical that these contrast signals be differentiated from true absorption features in the planetary atmosphere. Here we present our work on simulating the contrast effect for an active stellar surface. We discuss the particular case of HD 189733 b, a well-studied hot Jupiter orbiting an active K-dwarf, due to the plethora of atomic absorption signals reported in its atmosphere.Specifically, we focus on Hα to address recent suggestions that the measured in-transit signals are a result of stellar activity. In the contrast model we include center-to-limb variations and calculate limb darkening parameters as a function of wavelength across the line of interest. The model includes contributions to the spectrum from spots, faculae and plages, filaments, and the bare stellar photosphere. Stellar rotation is also included. We find that it is very difficult to reproduce the measured in-transit Hα signals for reasonable active region parameters. In addition, it is difficult to create an in-transit contrast signature that lasts for the duration of the transit unless the planet is crossing an active latitudinal belt and is always obscuring active regions. This suggests that the Hα measurements arise predominantly in the planetary atmosphere. However, the contrast effect likely contributes to these signals. Furthermore, our results could be

  11. Gas chromatography of organic microcontaminants using atomic emission and mass spectrometric detection combined in one instrument (GC-AED/MS)

    NARCIS (Netherlands)

    Mol, H.G.J.; Hankemeier, T.; Brinkman, U.A.T.

    1999-01-01

    This study describes the coupling of an atomic-emission detector and mass-spectrometric detector to a single gas chromatograph. Splitting of the column effluent enables simultaneous detection by atomic-emission detection (AED) and mass spectrometry (MS) and yields a powerful system for the target an

  12. Reactions of atomic cations with methane: gas phase room-temperature kinetics and periodicities in reactivity.

    Science.gov (United States)

    Shayesteh, Alireza; Lavrov, Vitali V; Koyanagi, Gregory K; Bohme, Diethard K

    2009-05-14

    Reactions of methane have been measured with 59 atomic metal cations at room temperature in helium bath gas at 0.35 Torr using an inductively-coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer. The atomic cations were produced at approximately 5500 K in an ICP source and allowed to decay radiatively and to thermalize by collisions with argon and helium atoms prior to reaction. Rate coefficients and product distributions are reported for the reactions of fourth-row atomic cations from K(+) to Se(+), of fifth-row atomic cations from Rb(+) to Te(+) (excluding Tc(+)), of sixth-row atomic cations from Cs(+) to Bi(+), and of the lanthanide cations from La(+) to Lu(+) (excluding Pm(+)). Two primary reaction channels were observed: C-H bond insertion with elimination of H(2), and CH(4) addition. The bimolecular H(2) elimination was observed in the reactions of CH(4) with As(+), Nb(+), and some sixth-row metal cations, i.e., Ta(+), W(+), Os(+), Ir(+), Pt(+); secondary and higher-order H(2) elimination was observed exclusively for Ta(+), W(+), and Ir(+) ions. All other transition-metal cations except Mn(+) and Re(+) were observed to react with CH(4) exclusively by addition, and up to two methane molecules were observed to add sequentially to most transition-metal ions. CH(4) addition was also observed for Ge(+), Se(+), La(+), Ce(+), and Gd(+) ions, while the other main-group and lanthanide cations did not react measurably with methane.

  13. The RESOLVE Survey Atomic Gas Census and Environmental Influences on Galaxy Gas Reservoirs

    CERN Document Server

    Stark, David V; Eckert, Kathleen D; Florez, Jonathan; Hall, Kirsten R; Watson, Linda C; Hoversten, Erik A; Burchett, Joseph N; Guynn, David T; Baker, Ashley D; Moffett, Amanda J; Berlind, Andreas A; Norris, Mark A; Haynes, Martha P; Giovanelli, Riccardo; Leroy, Adam K; Pisano, D J; Wei, Lisa H; Gonzalez, Roberto E; Calderon, Victor F

    2016-01-01

    We present the HI mass inventory for the RESOLVE survey, a volume-limited, multi-wavelength census of >1500 z=0 galaxies spanning diverse environments and complete in baryonic mass down to dwarfs of 10^9 Msun. This first 21cm data release provides robust detections or strong upper limits (1.4M_HI 10^12 Msun) halos, suggesting that gas stripping and/or starvation may be induced by interactions with larger halos or the surrounding cosmic web. We find that the detailed relationship between G/S and environment varies when we examine different subvolumes of RESOLVE independently, which we suggest may be a signature of assembly bias.

  14. Exploring star formation in high-z galaxies using atomic and molecular emission lines

    Science.gov (United States)

    Gullberg, Bitten

    2016-03-01

    The conditions under which stars are formed and the reasons for triggering and quenching of starburst events in high-z galaxies, are still not well understood. Studying the interstellar medium (ISM) and the morphology of high-z galaxies are therefore key points in order to understand galaxy evolution. The cosmic star formation rate density peaks between 1thesis presents three studies of the ISM in high-z galaxies and their morphologies by: Exploring the physical conditions of the ISM in a sample of dusty star-forming galaxies (DSFGs) using the relative observed line strength of ionised carbon ([CII]) and carbon monoxide (CO). We find that the line ratios can best be described by a medium of [CII] and CO emitting gas with a higher [CII] than CO excitation temperature, high CO optical depth tau(CO)>>1, and low to moderate [CII] optical depth tau(CII)2, pave the road for future investigations of the star-forming ISM in high-z galaxies, by illustrating the importance of multi-wavelength, fine structure- and molecular line studies.

  15. Atomic-to-molecular gas phase transition triggered by the radio jet in Centaurus A

    CERN Document Server

    Salomé, Quentin; Combes, Françoise; Hamer, Stephen

    2016-01-01

    NGC 5128 (Centaurus A) is one of the best example to study AGN-feedback in the local Universe. At 13.5 kpc from the galaxy, optical filaments with recent star formation are lying along the radio-jet direction. We used the Atacama Pathfinder EXperiment (APEX) to map the CO(2-1) emission all along the filament structure. Molecular gas mass of 8.2x10^7 Msun was found over the 4.2 kpc-structure which represents about 3% of the total gas mass of the NGC 5128 cold gas content. Two dusty mostly molecular structure are identified, following the optical filaments. The region corresponds to the crossing of the radio jet with the Northern HI shell, coming from a past galaxy merger. One filament is located at the border of the HI shell, while the other is entirely molecular, and devoid of HI gas. The molecular mass is comparable to the HI mass in the shell, suggesting a scenario where the atomic gas was shocked and transformed in molecular clouds by the radio jet. Comparison with combined FIR Herschel and UV GALEX estima...

  16. Assessment of corrosion in the flue gas cleaning system using on-line monitoring

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Vendelbo Nielsen, Lars; Berggreen Petersen, Michael

    2015-01-01

    Amager unit 1 is a 350 MW multifuel suspension-fired plant commissioned in 2009 to fire biomass (straw and wood pellets). Increasing corrosion problems in the flue gas cleaning system were observed in the gas-gas preheater (GAFO), the booster fan and flue gas ducts. Chlorine containing corrosion...... products/deposits were detected. An on-line corrosion measurement system was established to determine corrosion mechanisms. It was revealed that many shutdowns/start-ups of the plant influence corrosion and result in decreased lifetime of components and increased maintenance. The change of fuel from...

  17. Development of a 2D temperature measurement technique for combustion diagnostics using 2-line atomic fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Engstroem, Johan

    2001-01-01

    The present thesis is concerned with the development and application of a novel planar laser-induced fluorescence (PLIF) technique for temperature measurements in a variety of combusting flows. Accurate measurement of temperature is an essential task in combustion diagnostics, since temperature is one of the most fundamental quantities for the characterization of combustion processes. The technique is based on two-line atomic fluorescence (TLAF) from small quantities of atomic indium (In) seeded into the fuel. It has been developed from small-scale experiments in laboratory flames to the point where practical combustion systems can be studied. The technique is conceptually simple and reveals temperature information in the post-flame regions. The viability of the technique has been tested in three extreme measurement situations: in spark ignition engine combustion, in ultra-lean combustion situations such as lean burning aero-engine concepts and, finally, in fuel-rich combustion. TLAF was successfully applied in an optical Sl engine using isooctane as fuel. The wide temperature sensitivity, 700 - 3000 K, of the technique using indium atoms allowed measurements over the entire combustion cycle in the engine to be performed. In applications in lean combustion a potential problem caused by the strong oxidation processes of indium atoms was encountered. This limits measurement times due to deposits of absorbing indium oxide on measurement windows. The seeding requirement is a disadvantage of the technique and can be a limitation in some applications. The results from experiments performed in sooting flames are very promising for thermometry measurements in such environments. Absorption by hydrocarbons and other native species was found to be negligible. Since low laser energies and low seeding concentrations could be used, the technique did not, unlike most other incoherent optical thermometry techniques, suffer interferences from LII of soot particles or LIF from PAH

  18. A vortex line for K-shell ionization of a carbon atom by electron impact

    Science.gov (United States)

    Ward, S. J.; Macek, J. H.

    2014-10-01

    We obtained using the Coulomb-Born approximation a deep minimum in the TDCS for K-shell ionization of a carbon atom by electron impact for the electron ejected in the scattering plane. The minimum is obtained for the kinematics of the energy of incident electron Ei = 1801.2 eV, the scattering angle θf = 4°, the energy of the ejected electron Ek = 5 . 5 eV, and the angle for the ejected electron θk = 239°. This minimum is due to a vortex in the velocity field. At the position of the vortex, the nodal lines of Re [ T ] and Im [ T ] intersect. We decomposed the CB1 T-matrix into its multipole components for the kinematics of a vortex, taking the z'-axis parallel to the direction of the momentum transfer vector. The m = +/- 1 dipole components are necessary to obtain a vortex. We also considered the electron to be ejected out of the scattering plane and obtained the positions of the vortex for different values of the y-component of momentum of the ejected electron, ky. We constructed the vortex line for the kinematics of Ei = 1801.2 eV and θf = 4°. S.J.W. and J.H.M. acknowledge support from NSF under Grant No. PHYS- 0968638 and from D.O.E. under Grant Number DE-FG02-02ER15283, respectively.

  19. A "Missing" Supernova Remnant revealed by the 21-cm Line of Atomic Hydrogen

    CERN Document Server

    Koo, B C; Salter, C J

    2006-01-01

    Although some 20--30,000 supernova remnants (SNRs) are expected to exist in the Milky Way, only about 230 are presently known. This implies that most SNRs are ``missing''. Recently, we proposed that small ($\\simlt 1^\\circ$), faint, high-velocity features seen in large-scale 21-cm line surveys of atomic hydrogen ({\\sc Hi}) in the Galactic plane could be examples of such {\\it missing} old SNRs. Here we report on high-resolution \\schi observations of one such candidate, FVW 190.2+1.1, which is revealed to be a rapidly expanding ($\\sim 80$ \\kms) shell. The parameters of this shell seem only consistent with FVW 190.2+1.1 being the remnant of a SN explosion that occurred in the outermost fringes of the Galaxy some $\\sim 3\\times 10^5$ yr ago. This shell is not seen in any other wave band suggesting that it represents the oldest type of SNR, that which is essentially invisible except via its \\schi line emission. FVW 190.2+1.1 is one of a hundred "forbidden-velocity wings" (FVWs) recently identified in the Galactic pl...

  20. Train of high-power femtosecond pulses: Probe wave in a gas of prepared atoms

    Science.gov (United States)

    Muradyan, Gevorg; Muradyan, Atom Zh.

    2009-09-01

    We present a method for generating a regular train of ultrashort optical pulses in a prepared two-level medium. The train develops from incident monochromatic probe radiation traveling in a medium of atoms, which are in a quantum mechanical superposition of dressed internal states. In the frame of linear theory for the probe radiation, the energy of individual pulses is an exponentially growing function of atom density and of interaction cross section. Pulse repetition rate is determined by the pump field’s generalized Rabi frequency and can be around 1 THz and greater. We also show that the terms, extra to the dipole approximation, endow the gas by a new property: nonsaturating dependence of refractive index on dressing monochromatic field intensity. Contribution of these nonsaturating terms can be compatible with the main dipole approximation term contribution in the wavelength region of about ten micrometers (the range of CO2 laser) or larger.

  1. Elemental speciation analysis by multicapillary gas chromatography with microwave-induced plasma atomic spectrometric detection.

    Science.gov (United States)

    Rodriguez Pereiro, I; Schmitt, V O; Lobiński, R

    1997-12-01

    Multicapillary column gas chromatography (MC-GC)/microwave-induced plasma atomic emission spectrometry (MIP AES) was developed for fast speciation analysis of organotin compounds in the environment. Ethylated butyltin compounds could be separated isothermally within less than 30 s (instead of ∼5-10 min) without sacrificing either the resolution or the sample capacity of conventional capillary GC with oven temperature gradient programming. Careful optimization of the pressure and temperature GC program allowed a comprehensive organotin speciation analysis including phenyltin compounds within less than 2.5 min, increasing the sample throughput 6-fold. Compatibility of MC-GC with an MIP atomic emission detector (MIP-AED) was discussed. MC-GC/MIP-AES was validated for the analysis of sediment (PACS-1 and BCR 462) and biological (NIES11) certified reference materials.

  2. Transverse azimuthal dephasing of vortex spin wave in a hot atomic gas

    CERN Document Server

    Shi, Shuai; Zhang, Wei; Zhou, Zhi-Yuan; Dong, Ming-Xin; Liu, Shi-Long; Shi, Bao-Sen; Guo, Guang-Can

    2016-01-01

    Optical fields with orbital angular momentum (OAM) interact with medium have many remarkable properties with its unique azimuthal phase, showing many potential applications in high capacity information processing, high precision measurement etc. The dephasing mechanics of optical fields with OAM in an interface between light and matter plays a vital role in many areas of physics. In this work, we study the transverse azimuthal dephasing of OAM spin wave in a hot atomic gas via OAM storage. The transverse azimuthal phase difference between the control and probe beams is mapped onto the spin wave, which essentially results in dephasing of atomic spin wave. The dephasing of OAM spin wave can be controlled by the parameters of OAM topological charge and beam waist. Our results are helpful for studying OAM light interaction with matter, maybe hold a promise in OAM-based quantum information processing.

  3. Site-resolved imaging of single atoms with a Faraday quantum gas microscope

    CERN Document Server

    Yamamoto, Ryuta; Kato, Kohei; Kuno, Takuma; Sakura, Yuto; Takahashi, Yoshiro

    2016-01-01

    We successfully demonstrate a quantum gas microscopy using the Faraday effect which has an inherently non-destructive nature. The observed Faraday rotation angle reaches 3.0(2) degrees for a single atom. We reveal the non-destructive feature of this Faraday imaging method by comparing the detuning dependence of the Faraday signal strength with that of the photon scattering rate. We determine the atom distribution with deconvolution analysis. We also demonstrate the absorption and the dark field Faraday imaging, and reveal the different shapes of the point spread functions for these methods, which are fully explained by theoretical analysis. Our result is an important first step towards an ultimate quantum non-demolition site-resolved imaging and furthermore opens up the possibilities for quantum feedback control of a quantum many-body system with a single-site resolution.

  4. Evidence for ferromagnetic instability in a repulsive Fermi gas of ultracold atoms

    CERN Document Server

    Valtolina, G; Amico, A; Burchianti, A; Recati, A; Enss, T; Inguscio, M; Zaccanti, M; Roati, G

    2016-01-01

    Ferromagnetism is among the most spectacular manifestations of interactions within many-body fermion systems. In contrast to weak-coupling phenomena, it requires strong repulsion to develop, making a quantitative description of ferromagnetic materials notoriously difficult. This is especially true for itinerant ferromagnets, where magnetic moments are not localized into a crystal lattice. In particular, it is still debated whether the simplest case envisioned by Stoner of a homogeneous Fermi gas with short-range repulsive interactions can exhibit ferromagnetism at all. In this work, we positively answer this question by studying a clean model system consisting of a binary spin-mixture of ultracold 6Li atoms, whose repulsive interaction is tuned via a Feshbach resonance. We drastically limit detrimental pairing effects that affected previous studies by preparing the gas in a magnetic domain-wall configuration. We reveal the ferromagnetic instability by observing the softening of the spin-dipole collective mode...

  5. Natural gas large volumes measurement: going for on-line custody transfer; Medicao de grandes volumes de gas natural: rumo a transferencia de custodia on-line

    Energy Technology Data Exchange (ETDEWEB)

    Mercon, Eduardo G.; Frisoli, Caetano [PETROBRAS Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil)

    2005-07-01

    This paper describes the structure of the natural gas flow measurement process in TRANSPETRO, and comments features and performance of existing or under-implantation equipment and systems, reviewing best practices and technology in use. This process runs through three interrelated segments: data flow measurement, strictly speaking; data transfer and acquisition; and data flow measurement certification (data consolidation to invoice). Initially, the work makes an approach to the data flow measurement segment, evaluating technical features of flow meters, and describing configurations and functions of the operating gas flow computers in TRANSPETRO's custody transfer stations. In this part it will also be presented the implantation of TRANSPETRO's system for gas chromatography data input on-line to flow computers. Further, in data transfer and acquisition, SCADA system technical aspects will be evaluated, considering communications protocols and programmable logic controllers functions in remote terminal units, and discussing their places in the measurement process. Additionally, TRANSPETRO's experience in data measurement certification tools is in discussion, as well as new upcoming tools and their potential features, from what new practices will be suggested. Finally, all the work has been conceived and carried out always aiming to the state-of-the-art technology in gas flow measurement: on-line custody transfer. (author)

  6. Gas Line Pressure Fluctuation Analysis of a Gas-Liquid Reactor

    Institute of Scientific and Technical Information of China (English)

    J.J.J. CHEN; J.C. ZHAO

    2005-01-01

    To ensure efficient operation of metallurgical gas-liquid reactors, the gas bubbles must be uniformly distributed.For high temperature metallurgical reactors, it is impractical and unsafe to carry out visual observations.An air-water model was used to study the relationship between the bubble flow patterns and the pressure fluctuation signals.The fluctuation signals captured in the time domain were transformed into the frequency domain. Various parameters obtained from the transformed data were analysed for their suitability for delineating the bubble flow pqtterns observed.These parameters and the flow patterns were found to be well-correlated using the gas flow number.

  7. Imaging spectrophotometry of ionized gas in NGC 1068. I - Kinematics of the narrow-line region

    Science.gov (United States)

    Cecil, Gerald; Bland, Jonathan; Tully, R. Brent

    1990-01-01

    The kinematics of collisionally excited forbidden N II 6548, 6583 across the inner 1 arcmin diameter of the nearby Seyfert galaxy NGC 1068 is mapped using an imaging Fabry-Perot interferometer and low-noise CCD. The stack of monochromatic images, which spatially resolved the high-velocity gas, was analyzed for kinematic and photometric content. Profiles agree well with previous long-slit work, and their complete spatial coverage makes it possible to constrain the gas volume distribution. It is found that the narrow-line region is distributed in a thick center-darkened, line-emitting cylinder that envelopes the collimated radio jet. Three distinct kinematic subsystems, of which the cylinder is composed, are discussed in detail. Detailed behavior of the emission-line profiles, at the few points in the NE quadrant with simple kinematics, argues that the ionized gas develops a significant component of motion perpendicular to the jet axis.

  8. Unexpected temporal evolution of atomic spectral lines of aluminum in a laser induced breakdown spectroscopy experiment

    Energy Technology Data Exchange (ETDEWEB)

    Saad, Rawad, E-mail: rawad.saad@cea.fr [CEA, DEN, DPC, SEARS, LANIE, 91191 Gif-sur-Yvette (France); L' Hermite, Daniel, E-mail: daniel.lhermite@cea.fr [CEA, DEN, DPC, SEARS, LANIE, 91191 Gif-sur-Yvette (France); Bousquet, Bruno, E-mail: bruno.bousquet@u-bordeaux1.fr [LOMA, Université de Bordeaux, CNRS, 351 Cours de la Libération, 33405 Talence Cedex (France)

    2014-11-01

    The temporal evolution of the laser induced breakdown (LIBS) signal of a pure aluminum sample was studied under nitrogen and air atmospheres. In addition to the usual decrease of signal due to plasma cooling, unexpected temporal evolutions were observed for a spectral lines of aluminum, which revealed the existence of collisional energy transfer effects. Furthermore, molecular bands of AlN and AlO were observed in the LIBS spectra, indicating recombination of aluminum with the ambient gas. Within the experimental conditions reported in this study, both collisional energy transfer and recombination processes occurred around 1.5 μs after the laser shot. This highlights the possible influence of collisional and chemical effects inside the plasma that can play a role on LIBS signals. - Highlights: • Persistence of two Al I lines related to the 61,844 cm{sup −1} energy level only under nitrogen atmosphere. • Collisional energy transfer effect exists between aluminum and nitrogen. • Observation of molecular band of AlN (under nitrogen) and AlO (under air) after a delay time of 1.5 µs. • 20% of oxygen in air is sufficient to annihilate both the collisional energy transfer effect and the AlN molecular formation.

  9. Friction Consolidation of Gas-Atomized Fe-Si Powders for Soft Magnetic Applications

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xiujuan; Whalen, Scott A.; Darsell, Jens T.; Mathaudhu, Suveen; Overman, Nicole R.

    2017-01-01

    Soft magnetic materials are often limited in scalability due to conventional processes that do not retain beneficial microstructures, and their associated physical properties, during densification. In this work, friction consolidation (FC) has been studied to fabricate Fe-Si soft magnetic materials from gas-atomized powder precursors. Fe-Si powder is consolidated using variable pressure and tool rotation speed in an effort to evaluate this unique densification approach for potential improvements in magnetic properties. FC, due to the high shear deformation involved, is shown to result in uniform gradual grain structure refinement across the consolidated workpiece from the center nearest the tool to the edge. Magnetic properties along different orientations indicate little, if any, textural orientation in the refined grain structure. The effect of annealing on the magnetic properties is evaluated and shown to decrease coercivity. FC processing was able to retain the magnetization of the original gas-atomized powders but further process optimization is needed to reach the optimal coercivity for the soft magnetic materials applications.

  10. Evolution of Molecular and Atomic Gas Phases in the Milky Way

    CERN Document Server

    Koda, Jin; Heyer, Mark

    2016-01-01

    We analyze radial and azimuthal variations of the phase balance between the molecular and atomic ISM in the Milky Way. In particular, the azimuthal variations -- between spiral arm and interarm regions -- are analyzed without any explicit definition of spiral arm locations. We show that the molecular gas mass fraction, i.e., fmol=H2/ (HI+H2) in mass, varies predominantly in the radial direction: starting from ~100% at the center, remaining ~>50% (~>60%) to R~6kpc, and decreasing to ~10-20% (~50%) at R=8.5 kpc when averaged over the whole disk thickness (in the mid plane). Azimuthal, arm-interarm variations are secondary: only ~20%, in the globally molecule-dominated inner MW, but becoming larger, ~40-50%, in the atom-dominated outskirts. This suggests that in the inner MW, the gas stays highly molecular (fmol>50%) as it goes from an interarm region, into a spiral arm, and back into the next interarm region. Stellar feedback does not dissociate molecules much, and the coagulation and fragmentation of molecular...

  11. Dispersed-phase structure of pressure-atomized sprays at various gas densities

    Science.gov (United States)

    Tseng, L.-K.; Wu, P.-K.; Faeth, G. M.

    1992-01-01

    The dispersed-phase structure of the dense-spray region of pressure-atomized sprays was studied for atomization breakup conditions, considering large-scale (9.5 mm initial diameter) water jets in still air at ambient pressures of 1, 2, and 4 atm., with both fully-developed turbulent pipe flow and nonturbulent slug flow at the jet exit. Drop sizes and velocities, and liquid volume fractions and fluxes, were measured using holography. Measurements were compared with predictions based on the locally-homogeneous flow approximation as well as recent correlations of drop sizes after primary breakup of turbulent and nonturbulent liquids. The dispersed-flow region beyond the liquid surface was relatively dilute (liquid volume fractions less than 0.1 percent), with significant separated-flow effects throughout, and evidence of near-limit secondary breakup and drop deformation near the liquid surface. Turbulent primary breakup predictions were satisfactory at atmospheric pressure, where the correlation was developed, but failed to predict observed trends of decreasing drop sizes with increasing gas density due to aerodynamic effects; in contrast, the laminar primary breakup predictions successfully treated the relatively small effects of gas density for this breakup mechanism. Effects of liquid turbulence at the jet exit were qualitatively similar to single-phase flows, yielding faster mixing rates with increased turbulence levels even though drop sizes tended to increase as well.

  12. Dynamics of gas-surface interactions atomic-level understanding of scattering processes at surfaces

    CERN Document Server

    Díez Muniño, Ricardo

    2013-01-01

    This book gives a representative survey of the state of the art of research on gas-surface interactions. It provides an overview of the current understanding of gas surface dynamics and, in particular, of the reactive and non-reactive processes of atoms and small molecules at surfaces. Leading scientists in the field, both from the theoretical and the experimental sides, write in this book about their most recent advances. Surface science grew as an interdisciplinary research area over the last decades, mostly because of new experimental technologies (ultra-high vacuum, for instance), as well as because of a novel paradigm, the ‘surface science’ approach. The book describes the second transformation which is now taking place pushed by the availability of powerful quantum-mechanical theoretical methods implemented numerically. In the book, experiment and theory progress hand in hand with an unprecedented degree of accuracy and control. The book presents how modern surface science targets the atomic-level u...

  13. Microstructure simulation of rapidly solidified ASP30 high-speed steel particles by gas atomization

    Science.gov (United States)

    Ma, Jie; Wang, Bo; Yang, Zhi-liang; Wu, Guang-xin; Zhang, Jie-yu; Zhao, Shun-li

    2016-03-01

    In this study, the microstructure evolution of rapidly solidified ASP30 high-speed steel particles was predicted using a simulation method based on the cellular automaton-finite element (CAFE) model. The dendritic growth kinetics, in view of the characteristics of ASP30 steel, were calculated and combined with macro heat transfer calculations by user-defined functions (UDFs) to simulate the microstructure of gas-atomized particles. The relationship among particle diameter, undercooling, and the convection heat transfer coefficient was also investigated to provide cooling conditions for simulations. The simulated results indicated that a columnar grain microstructure was observed in small particles, whereas an equiaxed microstructure was observed in large particles. In addition, the morphologies and microstructures of gas-atomized ASP30 steel particles were also investigated experimentally using scanning electron microscopy (SEM). The experimental results showed that four major types of microstructures were formed: dendritic, equiaxed, mixed, and multi-droplet microstructures. The simulated results and the available experimental data are in good agreement.

  14. Photon stimulated desorption of and nuclear resonant scattering by noble gas atoms at solid surfaces

    CERN Document Server

    Ikeda, Akihiko

    2015-01-01

    When a noble gas atom approaches a solid surface, it is adsorbed via the Van der Waals force, which is called physisorption. In this thesis, several experimental results concerning physisorbed atoms at surfaces are presented. First, photon stimulated desorption of Xe atoms from a Au substrate using nano-second laser is presented. With the time-of-flight measurements, the translational temperature and the desorption yield of desorbing Xe as a function of laser fluence are obtained. It is discovered that there are non-thermal and thermal desorption pathways. It is discussed that the former path involves a transient formation of the negative ion of Xe. The desorption flux dependence of the thermal pathway is also investigated. We found that at a large desorption fluxes the desorption flow is thermalized due to the post-desorption collisions. The resultant velocity and the temperature of the flow is found to be in good agreement with the theoretical predictions based on the Knudsen layer formation. Lastly, nuclea...

  15. Coqblin-Schrieffer model for an ultracold gas of ytterbium atoms with metastable state

    Science.gov (United States)

    Kuzmenko, Igor; Kuzmenko, Tetyana; Avishai, Yshai; Jo, Gyu-Boong

    2016-03-01

    Motivated by the impressive recent advance in manipulating cold ytterbium atoms, we explore and substantiate the feasibility of realizing the Coqblin-Schrieffer model in a gas of cold fermionic 173Yb atoms. Making use of different AC polarizabillity of the electronic ground state (electronic configuration S10) and the long lived metastable state (electronic configuration P30), it is substantiated that the latter can be localized and serve as a magnetic impurity while the former remains itinerant. The exchange mechanism between the itinerant S10 and the localized P30 atoms is analyzed and shown to be antiferromagnetic. The ensuing SU(6) symmetric Coqblin-Schrieffer Hamiltonian is constructed, and, using the calculated exchange constant J , perturbative renormalization group (RG) analysis yields the Kondo temperature TK that is experimentally accessible. A number of thermodynamic measurable observables are calculated in the weak-coupling regime T >TK (using perturbative RG analysis) and in the strong-coupling regime T

  16. Absorption line profile recovery based on TDLS and MEMS micro-mirror for photoacoustic gas sensing.

    Science.gov (United States)

    Li, Li; Arsad, Norhana; Stewart, George; Thursby, Graham; Uttamchandani, Deepak; Culshaw, Brian; Yi-ding, Wang

    2011-07-01

    A novel and efficient absorption line recovery technique is presented. A micro-electromechanical systems (MEMS) mirror driven by an electrothermal actuator is used to generate laser intensity modulation through the mirror reflection. Tunable diode laser spectroscopy (TDLS) and photoacoustic spectroscopy (PAS) are used to recover the target absorption line profile which is compared with the theoretical Voigt profile. The target gas is 0.01% acetylene (C2H2) in a nitrogen host gas. The laser diode wavelength is swept across the P17 absorption line of acetylene at 1535.4 nm by a current ramp, and an erbium-doped fibre amplifier (EDFA) is used to enhance the optical intensity and increase the signal-to-noise ratio (SNR). A SNR of about 35 is obtained with 100 mW laser power from the EDFA. Good agreement is achieved between the experimental results and the theoretical simulation for the P17 absorption line profile.

  17. Absorption Line Profile Recovery Based on TDLS and MEMS Micro-Mirror for Photoacoustic Gas Sensing

    Institute of Scientific and Technical Information of China (English)

    LI Li; Norhana Arsad; George Stewart; Graham Thursby; Deepak Uttamchandani; Brian Culshaw; WANG Yi-ding

    2011-01-01

    A novel and efficient absorption line recovery technique is presented. A micro-electromechanical systems (MEMS) mirror driven by an electrothermal actuator is used to generate laser intensity modulation through the mirror reflection. Tunable diode laser spectroscopy (TDLS) and photoacoustic spectroscopy (PAS) are used to recover the target absorption line profile which is compared with the theoretical Voigt profile. The target gas is 0.01% acetylene (C2 H2 ) in a nitrogen host gas. The laser diode wavelength is swept across the P17 absorption line of acetylene at 1 535.4 nm by a current ramp, and an erbium-doped fibre amplifier (EDFA) is used to enhance the optical intensity and increase the signal-to-noise ratio (SNR). A SNR of about 35 is obtained with 100 mW laser power from the EDFA Good agreement is achieved between the experimental results and the theoretical simulation for the P17 absorption line profile.

  18. ATOMIC DATA FOR ABSORPTION-LINES FROM THE GROUND-LEVEL AT WAVELENGTHS GREATER-THAN-228-ANGSTROM

    NARCIS (Netherlands)

    VERNER, DA; BARTHEL, PD; TYTLER, D

    1994-01-01

    We list wavelengths, statistical weigths and oscillator strengths for 2249 spectral lines arising from the ground states of atoms and ions. The compilation covers all wavelengths longward of the HeII Lyman limit at 227.838 Angstrom and all the ion states of all elements from hydrogen to bismuth (Z =

  19. The solar photospheric abundance of carbon. Analysis of atomic carbon lines with the CO5BOLD solar model

    NARCIS (Netherlands)

    Caffau, E.; Ludwig, H.-G.; Bonifacio, P.; Faraggiana, R.; Steffen, M.; Freytag, B.; Kamp, I.; Ayres, T. R.

    2010-01-01

    Context. The analysis of the solar spectra using hydrodynamical simulations, with a specific selection of lines, atomic data, and method for computing deviations from local thermodynamical equilibrium, has led to a downward revision of the solar metallicity, Z. We are using the latest simulations co

  20. Molecular Gas Kinematics and Line Diagnostics in Early-type Galaxies: NGC4710 and NGC5866

    CERN Document Server

    Topal, Selcuk; Davis, Timothy A; Krips, Melanie; Young, Lisa M; Crocker, Alison F

    2016-01-01

    We present interferometric observations of CO lines (12CO(1-0, 2-1) and 13CO(1-0, 2-1)) and dense gas tracers (HCN(1-0), HCO+(1-0), HNC(1-0) and HNCO(4-3)) in two nearby edge-on barred lenticular galaxies, NGC 4710 and NGC 5866, with most of the gas concentrated in a nuclear disc and an inner ring in each galaxy. We probe the physical conditions of a two-component molecular interstellar medium in each galaxy and each kinematic component by using molecular line ratio diagnostics in three complementary ways. First, we measure the ratios of the position-velocity diagrams of different lines, second we measure the ratios of each kinematic component's integrated line intensities as a function of projected position, and third we model these line ratios using a non-local thermodynamic equilibrium radiative transfer code. Overall, the nuclear discs appear to have a tenuous molecular gas component that is hotter, optically thinner and with a larger dense gas fraction than that in the inner rings, suggesting more dense ...

  1. Neutral atomic-carbon QSO absorption-line systems at z>1.5: Sample selection, HI content, reddening, and 2175 A extinction feature

    CERN Document Server

    Ledoux, C; Petitjean, P; Srianand, R

    2015-01-01

    We present the results of a search for cold gas at high redshift along QSO lines-of-sight carried out without any a priori assumption on the neutral atomic-hydrogen (HI) content of the absorbers. To do this, we systematically looked for neutral-carbon (CI) 1560,1656 transition lines in low-resolution QSO spectra from the SDSS database. We built up a sample of 66 CI absorbers with redshifts 1.521 compared to systematic DLA surveys. We study empirical relations between W_r(CI), N(HI), E(B-V) and the strength of the 2175 A extinction feature, the latter being detected in about 30% of the CI absorbers. We show that the 2175 A feature is weak compared to Galactic lines-of-sight exhibiting the same amount of reddening. This is probably the consequence of current or past star formation in the vicinity of the CI systems. We also find that the strongest CI systems tend to have the largest amounts of dust and that the metallicity of the gas and its molecular fraction is likely to be high in a large number of cases.

  2. Lateral line pore diameters correlate with the development of gas bubble trauma signs in several Columbia River fishes

    Science.gov (United States)

    Morris, R.G.; Beeman, J.W.; VanderKooi, S.P.; Maule, A.G.

    2003-01-01

    Gas bubble trauma (GBT) caused by gas supersaturation of river water continues to be a problem in the Columbia River Basin. A common indicator of GBT is the percent of the lateral line occluded with gas bubbles; however, this effect has never been examined in relation to lateral line morphology. The effects of 115, 125 and 130% total dissolved gas levels were evaluated on five fish species common to the upper Columbia River. Trunk lateral line pore diameters differed significantly (Psucker>largescale sucker>northern pikeminnow???chinook salmon???redside shiner). At all supersaturation levels evaluated, percent of lateral line occlusion exhibited an inverse correlation to pore size but was not generally related to total dissolved gas level or time of exposure. This study suggests that the differences in lateral line pore diameters between species should be considered when using lateral line occlusion as an indicator of gas bubble trauma. ?? 2003 Elsevier Science Inc. All rights reserved.

  3. Greenhouse Gas Impact of Ridership on Sheppard Subway Line, Toronto, Canada

    OpenAIRE

    Saxe, Shoshanna; Cruickshank, Heather; Miller, Eric

    2015-01-01

    This is a metadata record relating to an article that cannot be shared due to publisher copyright. Changes in travel behavior near the Sheppard Subway Line in Toronto, Ontario, Canada, and the associated greenhouse gas impacts were examined. A study looked at initial changes in mode share after the line opened in 2002 and examined ongoing mode share trends through 2012. The initial mode shift was assessed through an analysis of bus boardings, subway platform counts, and traffic counts made...

  4. The photospheric solar oxygen project: I. Abundance analysis of atomic lines and influence of atmospheric models

    CERN Document Server

    Caffau, Elisabetta; Steffen, Matthias; Ayres, Thomas R; Bonifacio, Piercarlo; Cayrel, Roger; Freytag, Bernd; Plez, Bertrand

    2008-01-01

    The solar oxygen abundance has undergone a major downward revision in the last decade, the most noticeable one being the update including 3D hydrodynamical simulations to model the solar photosphere. Up to now, such an analysis has been carried out only by one group using one radiation-hydrodynamics code. We investigate the photospheric oxygen abundance considering lines from atomic transitions. We also consider the relationship between the solar model used and the resulting solar oxygen abundance, to understand whether the downward abundance revision is specifically related to 3D hydrodynamical effects. We perform a new determination of the solar photospheric oxygen abundance by analysing different high-resolution high signal-to-noise ratio atlases of the solar flux and disc-centre intensity making use of the latest generation of CO5BOLD 3D solar model atmospheres. We find 8.73 < logNoxygen/Nhydrogen +12 < 8.79. The lower and upper value represent extreme assumptions on the role of collisional excitati...

  5. Dark Atoms and the Positron-Annihilation-Line Excess in the Galactic Bulge

    Directory of Open Access Journals (Sweden)

    J.-R. Cudell

    2014-01-01

    Full Text Available It was recently proposed that stable particles of charge −2, O--, can exist and constitute dark matter after they bind with primordial helium in O-helium (OHe atoms. We study here in detail the possibility that this model provides an explanation for the excess of gamma radiation in the positron-annihilation line from the galactic bulge observed by INTEGRAL. This explanation assumes that OHe, excited to a 2s state through collisions in the central part of the Galaxy, deexcites to its ground state via an E0 transition, emitting an electron-positron pair. The cross-section for OHe collisions with excitation to 2s level is calculated and it is shown that the rate of such excitations in the galactic bulge strongly depends not only on the mass of O-helium, which is determined by the mass of O--, but also on the density and velocity distribution of dark matter. Given the astrophysical uncertainties on these distributions, this mechanism constrains the O-- mass to lie in two possible regions. One of these is reachable in the experimental searches for stable multicharged particles at the LHC.

  6. Utilization of on-line corrosion monitoring in the flue gas cleaning system

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Nielsen, Lars V.; Petersen, Michael B.

    2015-01-01

    The power plant unit 1 at Amager, Denmark is a 350 MWth multifuel suspension-fired plant commissioned in 2009 which uses biomass. Increasing corrosion problems in the flue gas cleaning system have been observed since 2011 in both the gas-gas preheater and the booster fan and booster fan duct...... such as HCl, KCl or chlorine containing corrosion products. Without knowing when corrosion occurs, it is difficult to take reasonable measures to reduce corrosion. In order to gain an improved understanding of the corrosion problem, an on-line corrosion measurement system was established before the booster...

  7. Gas entrainment rate coefficient of an ideal momentum atomizing liquid jet

    CERN Document Server

    Medrano, Fermín Franco; Velte, Clara Marika; Hodžić, Azur

    2016-01-01

    We propose a two-phase-fluid model for a turbulent full-cone high speed atomizing liquid jet that describes its dynamics in a simple but comprehensive manner with only the apex angle of the cone being a disposable parameter. The basic assumptions are that (i) the jet is statistically stationary and that (ii) it can be approximated by a mixture of a liquid and a gas with its phases in dynamic equilibrium. To derive the model, we impose conservation of the liquid volume and total momentum fluxes. Our model equation admits analytical solutions for the composite density and velocity of the two-phase fluid, both as functions of the distance from the nozzle, from which the dynamic pressure and gas the entrainment rate coefficient are calculated. Assuming a far-field approximation, we theoretically derive a constant gas entrainment rate coefficient solely in terms of the cone angle. Moreover, we carry out experiments for a single-phase turbulent air jet and show that the predictions of our model compare well with th...

  8. Determination of selenium and tellurium in the gas phase using specific columns and atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Muangnoicharoen, S.; Chiou, K.Y.; Manuel, O.K.

    1986-11-01

    Total selenium and tellurium in the gas phase were analyzed after adsorption on gold-coated beads and charcoal. The thermally eluting gas was trapped on columns filled with quartz beads that were cooled in an ice bath. The beads were boiled in dilute HCl, and the resulting solution was analyzed for Se and Te by graphite furnace atomic absorption spectrometry. Their results demonstrate that gold-coated beads efficiently trap gaseous Se and Te at a low gas flow rate, but at higher flow rates charcoal traps are more expedient. With charcoal traps, it was found that local air samples contain Se in the range of 0.92-3.05 ng m/sup -3/ and Te in the range of 0.10-0.34 ng m/sup -3/. Detection limits down to about 0.1 ng m/sup -3/ allow the ready detection of Se and Te in rural air with a precision of about +/- 6% at the nanogram level of Te and about +/- 4% at the nanogram level of Se.

  9. Dynamics of the gas-liquid interfacial reaction of O(3P) atoms with hydrocarbons

    Science.gov (United States)

    Kelso, Hailey; Köhler, Sven P. K.; Henderson, David A.; McKendrick, Kenneth G.

    2003-11-01

    We describe an experimental approach to the determination of the nascent internal state distribution of gas-phase products of a gas-liquid interfacial reaction. The system chosen for study is O(3P) atoms with the surface of liquid deuterated squalane, a partially branched long-chain saturated hydrocarbon, C30D62. The nascent OD products are detected by laser-induced fluorescence. Both OD (v'=0) and (v'=1) were observed in significant yield. The rotational distributions in both vibrational levels are essentially the same, and are characteristic of a Boltzmann distribution at a temperature close to that of the liquid surface. This contrasts with the distributions in the corresponding homogeneous gas-phase reactions. We propose a preliminary interpretation in terms of a dominant trapping-desorption mechanism, in which the OD molecules are retained at the surface sufficiently long to cause rotational equilibration but not complete vibrational relaxation. The significant yield of vibrationally excited OD also suggests that the surface is not composed entirely of -CD3 endgroups, but that secondary and/or tertiary units along the backbone are exposed.

  10. All-gas-phase synthesis of UiO-66 through modulated atomic layer deposition

    Science.gov (United States)

    Lausund, Kristian Blindheim; Nilsen, Ola

    2016-01-01

    Thin films of stable metal-organic frameworks (MOFs) such as UiO-66 have enormous application potential, for instance in microelectronics. However, all-gas-phase deposition techniques are currently not available for such MOFs. We here report on thin-film deposition of the thermally and chemically stable UiO-66 in an all-gas-phase process by the aid of atomic layer deposition (ALD). Sequential reactions of ZrCl4 and 1,4-benzenedicarboxylic acid produce amorphous organic–inorganic hybrid films that are subsequently crystallized to the UiO-66 structure by treatment in acetic acid vapour. We also introduce a new approach to control the stoichiometry between metal clusters and organic linkers by modulation of the ALD growth with additional acetic acid pulses. An all-gas-phase synthesis technique for UiO-66 could enable implementations in microelectronics that are not compatible with solvothermal synthesis. Since this technique is ALD-based, it could also give enhanced thickness control and the possibility to coat irregular substrates with high aspect ratios. PMID:27876797

  11. The Fueling Diagram: Linking Galaxy Molecular-to-Atomic Gas Ratios to Interactions and Accretion

    CERN Document Server

    Stark, David V; Wei, Lisa H; Baker, Andrew J; Leroy, Adam K; Eckert, Kathleen D; Vogel, Stuart N

    2013-01-01

    To assess how external factors such as local interactions and fresh gas accretion influence the global ISM of galaxies, we analyze the relationship between recent enhancements of central star formation and total molecular-to-atomic (H2/HI) gas ratios, using a broad sample of field galaxies spanning early-to-late type morphologies, stellar masses of 10^(7.2-11.2) Msun, and diverse stages of evolution. We find that galaxies occupy several loci in a "fueling diagram" that plots H2/HI vs. mass-corrected blue-centeredness, a metric tracing the degree to which galaxies have bluer centers than the average galaxy at their stellar mass. Spiral galaxies show a positive correlation between H2/HI and mass-corrected blue-centeredness. When combined with previous results linking mass-corrected blue-centeredness to external perturbations, this correlation suggests a link between local galaxy interactions and molecular gas inflow/replenishment. Intriguingly, E/S0 galaxies show a more complex picture: some follow the same cor...

  12. All-gas-phase synthesis of UiO-66 through modulated atomic layer deposition

    Science.gov (United States)

    Lausund, Kristian Blindheim; Nilsen, Ola

    2016-11-01

    Thin films of stable metal-organic frameworks (MOFs) such as UiO-66 have enormous application potential, for instance in microelectronics. However, all-gas-phase deposition techniques are currently not available for such MOFs. We here report on thin-film deposition of the thermally and chemically stable UiO-66 in an all-gas-phase process by the aid of atomic layer deposition (ALD). Sequential reactions of ZrCl4 and 1,4-benzenedicarboxylic acid produce amorphous organic-inorganic hybrid films that are subsequently crystallized to the UiO-66 structure by treatment in acetic acid vapour. We also introduce a new approach to control the stoichiometry between metal clusters and organic linkers by modulation of the ALD growth with additional acetic acid pulses. An all-gas-phase synthesis technique for UiO-66 could enable implementations in microelectronics that are not compatible with solvothermal synthesis. Since this technique is ALD-based, it could also give enhanced thickness control and the possibility to coat irregular substrates with high aspect ratios.

  13. The Properties of Lyα Nebulae: Gas Kinematics from Nonresonant Lines

    Science.gov (United States)

    Yang, Yujin; Zabludoff, Ann; Jahnke, Knud; Davé, Romeel

    2014-10-01

    With the Very Large Telescope/X-shooter, we obtain optical and near-infrared spectra of six Lyα blobs at z ~ 2.3. For a total sample of eight Lyα blobs (including two that we have previously studied), the majority (6/8) have broadened Lyα profiles with shapes ranging from a single peak to symmetric or asymmetric double-peaked. The remaining two systems, in which the Lyα profile is not significantly broader than the [O III] or Hα emission lines, have the most spatially compact Lyα emission, the smallest offset between the Lyα and the [O III] or Hα line velocities, and the only detected C IV and He II lines in the sample, implying that a hard ionizing source, possibly an active galactic nucleus (AGN), is responsible for their lower optical depth. Using three measures—the velocity offset between the Lyα line and the nonresonant [O III] or Hα line (Δv Lyα), the offset of stacked interstellar metal absorption lines, and a new indicator, the spectrally resolved [O III] line profile—we study the kinematics of gas along the line of sight to galaxies within each blob center. These three indicators generally agree in velocity and direction and are consistent with a simple picture in which the gas is stationary or slowly outflowing at a few hundred km s-1 from the embedded galaxies. The absence of stronger outflows is not a projection effect: the covering fraction for our sample is limited to metal absorption line offsets suggest no significant bulk motion, we use a simple radiative transfer model to make the first column density measurement of gas in an embedded galaxy, finding it consistent with a damped Lyα absorption system. Overall, the absence of clear inflow signatures suggests that the channeling of gravitational cooling radiation into Lyα is not significant over the radii probed here. However, one peculiar system (CDFS-LAB10) has a blueshifted Lyα component that is not obviously associated with any galaxy, suggesting either displaced gas arising

  14. Studies of Pressure-Broadening of Alkali Atom Resonance Lines for Modeling Atmospheres of Extrasolar Giant Planets and Brown Dwarfs

    Science.gov (United States)

    Kirby, Kate; Babb, J.; Yoshino, K.

    2004-01-01

    In L-dwarfs and T-dwarfs the resonance lines of sodium and potassium are so profoundly pressure-broadened that their wings extend several hundred nanometers from line center. With accurate knowledge of the line profiles as a function of temperature and pressure: such lines can prove to be valuable diagnostics of the atmospheres of such objects. We have initiated a joint program of theoretical and experimental research to study the line-broadening of alkali atom resonance lines due to collisions with species such as helium and molecular hydrogen. Although potassium and sodium are the alkali species of most interest in the atmospheres of cool brown dwarfs and extrasolar giant planets, some of our theoretical focus this year has involved the calculation of pressure-broadening of lithium resonance lines by He, as a test of a newly developed suite of computer codes. In addition, theoretical calculations have been carried out to determine the leading long range van der Waals coefficients for the interactions of ground and excited alkali metal atoms with helium atoms, to within a probable error of 2%. Such data is important in determining the behavior of the resonance line profiles in the far wings. Important progress has been made on the experimental aspects of the program since the arrival of a postdoctoral fellow in September. A new absorption cell has been designed, which incorporates a number of technical improvements over the previous cell, including a larger cell diameter to enhance the signal, and fittings which allow for easier cleaning, thereby significantly reducing the instrument down-time.

  15. Gas Temperature Measurements of Fluctuating Coal - MHD Plasmas Using Modified Line Reversal.

    Science.gov (United States)

    Winkleman, Bradley Carl

    The technique of modified line reversal is investigated and developed to allow accurate measurements on fluctuating coal fired magnetohydrodynamic plasmas and flows. Generalized modified line reversal equations applicable to any geometry and optical system are developed and presented. The generalized equations are specialized to the two most common optical systems, focussed and collimated, employed for modified line reversal measurements. Approximations introduced by specializing to the specific optical systems are investigated. Vignetting of the optical system images is shown to introduce large biases in the temperature measurement for certain optical configurations commonly applied. It is shown that symmetric optical systems are unacceptable for line reversal measurements. The errors introduced by non-simultaneous measurement of the required line reversal parameters due to rapidly fluctuating plasma characteristics are characterized. Line reversal signal and temperature measurements made on a coal fired MHD plasma are used to quantify the error in the temperature measurement due to non-simultaneous sampling of the measured line reversal parameters. A simple modified line reversal system based on interference filters and photodiodes that employs spatial separation to obtain the required line reversal parameters is described. Gas temperatures measured with devices using both the spatial and temporal separation techniques are compared. Modified line reversal temperature measurements are compared to theoretically predicted temperatures as well as CARS and high velocity thermocouple temperature measurements.

  16. Zeeman shift--a tool for assignment of 14N NQR lines of nonequivalent 14N atoms in powder samples.

    Science.gov (United States)

    Luznik, J; Jazbinsek, V; Pirnat, J; Seliger, J; Trontelj, Z

    2011-09-01

    The use of Zeeman perturbed 14N nuclear quadrupole resonance (NQR) to determine the ν+ and ν-14N lines in polycrystalline samples with several nonequivalent nitrogen atoms was investigated. The 14N NQR line shift due to a weak external Zeeman magnetic field was calculated, assuming isotropic distribution of EFG tensor directions. We calculated the broad line distribution of the ν+ and ν- line shifts and experimentally confirmed the calculated Zeeman field dependence of singularities (NQR peaks) in cyclotrimethylenetrinitramine (RDX) and aminotetrazole monohydrate (ATMH). The calculated and measured frequency shifts agreed well. The proposed measurement method enabled determination of which 14N NQR lines in ATMH belong to ν+ and which to ν- transitions.

  17. Gaia-ESO Survey: Gas dynamics in the Carina Nebula through optical emission lines

    CERN Document Server

    Damiani, F; Magrini, L; Prisinzano, L; Mapelli, M; Micela, G; Kalari, V; Apellaniz, J Maiz; Gilmore, G; Randich, S; Alfaro, E; Flaccomio, E; Koposov, S; Klutsch, A; Lanzafame, A C; Pancino, E; Sacco, G G; Bayo, A; Carraro, G; Casey, A R; Costado, M T; Franciosini, E; Hourihane, A; Lardo, C; Lewis, J; Monaco, L; Morbidelli, L; Worley, C; Zaggia, S; Zwitter, T; Dorda, R

    2016-01-01

    We present observations from the Gaia-ESO Survey in the lines of H$\\alpha$, [N II], [S II] and He I of nebular emission in the central part of the Carina Nebula. We investigate the properties of the two already known kinematic components (approaching and receding, respectively), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV $>$50 km/s) gas emission. We show that gas giving rise to H$\\alpha$ and He I emission is dynamically well correlated, but not identical, to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arises from several distinct shell-like expanding regions, the most evident found around $\\eta$ Car, the Trumpler 14...

  18. Spectral narrowing of coherent population trapping resonance in laser-cooled and room-temperature atomic gas

    Indian Academy of Sciences (India)

    S Pradhan; S Mishra; R Behera; N Kawade; A K Das

    2014-02-01

    We have investigated coherent population trapping (CPT) in laser-cooled as well as room-temperature (with and without buffer gas) rubidium atoms. The characteristic broad signal profile emerging from the two-photon Raman resonance for room-temperature atomic vapour is consistent with the theoretical calculation incorporating associated thermal averaging. The spectral width of the dark resonance obtained with cold atoms is found to be broadened, compared to roomtemperature vapour cell, due to the feeble role played by thermal averaging, although the cold atomic sample significantly overcomes the limitation of the transit time broadening. An alternative way to improve transit time is to use a buffer gas, with which we demonstrate that the coherent population trapping signal width is reduced to < 540 Hz.

  19. Recovering Interstellar Gas Properties with Hi Spectral Lines: A Comparison between Synthetic Spectra and 21-SPONGE

    Science.gov (United States)

    Murray, Claire E.; Stanimirović, Snežana; Kim, Chang-Goo; Ostriker, Eve C.; Lindner, Robert R.; Heiles, Carl; Dickey, John M.; Babler, Brian

    2017-03-01

    We analyze synthetic neutral hydrogen (H i) absorption and emission spectral lines from a high-resolution, three-dimensional hydrodynamical simulation to quantify how well observational methods recover the physical properties of interstellar gas. We present a new method for uniformly decomposing H i spectral lines and estimating the properties of associated gas using the Autonomous Gaussian Decomposition (AGD) algorithm. We find that H i spectral lines recover physical structures in the simulation with excellent completeness at high Galactic latitude, and this completeness declines with decreasing latitude due to strong velocity-blending of spectral lines. The temperature and column density inferred from our decomposition and radiative transfer method agree with the simulated values within a factor of Large Array using AGD. We find more components per line of sight in 21-SPONGE than in synthetic spectra, which reflects insufficient simulated gas scale heights and the limitations of local box simulations. In addition, we find a significant population of low-optical depth, broad absorption components in the synthetic data which are not seen in 21-SPONGE. This population is not obvious in integrated or per-channel diagnostics, and reflects the benefit of studying velocity-resolved components. The discrepant components correspond to the highest spin temperatures (1000< {T}s< 4000 {{K}}), which are not seen in 21-SPONGE despite sufficient observational sensitivity. We demonstrate that our analysis method is a powerful tool for diagnosing neutral interstellar medium conditions, and future work is needed to improve observational statistics and implementation of simulated physics.

  20. First detection of the 63 μm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA

    Science.gov (United States)

    Rezac, L.; Hartogh, P.; Güsten, R.; Wiesemeyer, H.; Hübers, H.-W.; Jarchow, C.; Richter, H.; Klein, B.; Honingh, N.

    2015-08-01

    Context. The Stratospheric Observatory for Infrared Astronomy (SOFIA) with its 2.5 m telescope provides new science opportunities for spectroscopic observations of planetary atmospheres in the far-infrared wavelength range. Aims: This paper presents first results from the 14 May, 2014 observing campaign of the Martian atmosphere at 4.7 THz using the German REceiver for Astronomy at Terahertz frequencies (GREAT) instrument. Methods: The atomic oxygen 63 μm transition, OI, was detected in absorption against the Mars continuum, with a high signal-to-noise ratio (~35). A beam-averaged atomic oxygen from a global circulation model was used as input to the radiative transfer simulations of the observed line area and to obtain a new estimate on the column density using a grid-search method. Results: Minimizing differences between the calculated and observed line intensities in the least-square sense yields an atomic oxygen column density of (1.1 ± 0.2) × 1017 cm-2. This value is about twice as low as predicted by a modern photochemical model of Mars. The radiative transfer simulations indicate that the line forms in the upper atmospheric region over a rather extended altitude region of 70-120 km. Conclusions: For the first time, a far-infrared transition of the atomic oxygen line was detected in the atmosphere of Mars. The absorption depth provides an estimate on the column density, and this measurement provides additional means to constrain the photochemical models in global circulation models and airglow studies. The lack of other means for monitoring the atomic oxygen in the Martian upper atmosphere makes future observations with the SOFIA observatory highly desirable. Appendix A is available in electronic form at http://www.aanda.org

  1. In situ gas phase measurements during metal alkylamide atomic layer deposition.

    Science.gov (United States)

    Maslar, J E; Kimes, W A; Sperling, B A

    2011-09-01

    Metal alkylamide compounds, such as tetrakis(ethylmethylamido) hafnium (TEMAH), represent a technologically important class of metalorganic precursors for the deposition of metal oxides and metal nitrides via atomic layer deposition (ALD) or chemical vapor deposition. The development of in situ diagnostics for processes involving these compounds could be beneficial in, e.g., developing deposition recipes and validating equipment-scale simulations. This report describes the performance of the combination of two techniques for the simultaneous, rapid measurement of the three major gas phase species during hafnium oxide thermal ALD using TEMAH and water: TEMAH, water, and methylethyl amine (MEA), the only major reaction by-product. For measurement of TEMAH and MEA, direct absorption methods based on a broadband infrared source with different mid-IR bandpass filters and utilizing amplitude modulation and synchronous detection were developed. For the measurement of water, wavelength modulation spectroscopy utilizing a near-IR distributed feedback diode laser was used. Despite the relatively simple reactor geometry employed here (a flow tube), differences were easily observed in the time-dependent species distributions in 300 mL/min of a helium carrier gas and in 1000 mL/min of a nitrogen carrier gas. The degree of TEMAH entrainment was lower in 300 mL/min of helium compared to that in 1000 mL/min of nitrogen. The capability to obtain detailed time-dependent species concentrations during ALD could potentially allow for the selection of carrier gas composition and flow rates that would minimize parasitic wall reactions. However, when nitrogen was employed at the higher flow rates, various flow effects were observed that, if detrimental to a deposition process, would effectively limit the upper range of useful flow rates.

  2. Cold and warm atomic gas around the Perseus molecular cloud I: Basic Properties

    CERN Document Server

    Stanimirovic, Snezana; Lee, Min-Young; Heiles, Carl; Miller, Jesse

    2014-01-01

    (Abridged) Using the Arecibo Observatory we have obtained neutral hydrogen (HI) absorption and emission spectral pairs in the direction of 26 background radio continuum sources in the vicinity of the Perseus molecular cloud. Strong absorption lines were detected in all cases allowing us to estimate spin temperature (T_s) and optical depth for 107 individual Gaussian components along these lines of sight. Basic properties of individual HI clouds (spin temperature, optical depth, and the column density of the cold and warm neutral medium, CNM and WNM) in and around Perseus are very similar to those found for random interstellar lines of sight sampled by the Millennium HI survey. This suggests that the neutral gas found in and around molecular clouds is not atypical. However, lines of sight in the vicinity of Perseus have on average a higher total HI column density and the CNM fraction, suggesting an enhanced amount of cold HI relative to an average interstellar field. Our estimated optical depth and spin temper...

  3. The Technical Specification and Physical Performance Level of Line Pipes for West-East Gas Pipeline

    Institute of Scientific and Technical Information of China (English)

    FengBin; WangMaotang; LiuFangming; XiaoLiming

    2004-01-01

    The west-east gas transmission engineering is an important project attracting domestic and foreign attention. The gas pipeline used in this project is a gas pipeline with the longest distance, largest pipe diameter and highest transmission pressure in the history of petroleum pipeline construction of China. For the construction of top-rank gas pipeline in the world with high standard, high speed and high benefit, the key of specifying production of metallurgical and pipe-making enterprises and ensuring quality performance of the steel and steel pipe is to research and formulate a feasible and satisfactory technical Specification for engineering steel and steel pipe with international level. In this paper the author introduces the establishment of the technical specification for West-East gas pipeline project, and lays emphasis on the analysis and discussion of principle and method determining major technical indexes related to line pipes for West-East gas pipeline. The author also introduces actual material selection of gas pipeline home and abroad, and presents examination and application of the technical specification for West-East gas pipeline.

  4. On-line least squares support vector machine algorithm in gas prediction

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiao-hu; WANG Gang; ZHAO Ke-ke; TAN De-jian

    2009-01-01

    Traditional coal mine safety prediction methods are off-line and do not have dynamic prediction functions. The Support Vector Machine (SVM) is a new machine learning algorithm that has excellent properties. The least squares support vector machine (LS-SVM) algorithm is an improved algorithm of SVM. But the common LS-SVM algorithm, used directly in safety predictions, has some problems. We have first studied gas prediction problems and the basic theory of LS-SVM. Given these problems, we have investigated the affect of the time factor about safety prediction and present an on-line prediction algorithm, based on LS-SVM. Finally, given our observed data, we used the on-line algorithm to predict gas emissions and used other related algorithm to com- pare its performance. The simulation results have verified the validity of the new algorithm.

  5. The Bose Gas and Asymmetric Simple Exclusion Process on the Half-Line

    CERN Document Server

    Tracy, Craig A

    2012-01-01

    In this paper we find explicit formulas for: (1) Green's function for a system of one-dimensional bosons interacting via a delta-function potential with particles confined to the positive half-line; and (2) the transition probability for the one-dimensional asymmetric simple exclusion process (ASEP) with particles confined to the nonnegative integers. These are both for systems with a finite number of particles. The formulas are analogous to ones obtained earlier for the Bose gas and ASEP on the line and integers, respectively. We use coordinate Bethe Ansatz appropriately modified to account for confinement of the particles to the half-line. As in the earlier work, the proof for the ASEP is less straightforward than for the Bose gas.

  6. Hyperfine frequencies of 87Rb and 133Cs atoms in Xe gas

    CERN Document Server

    McGuyer, B H; Happer, W; 10.1103/PhysRevA.84.030501

    2013-01-01

    The microwave resonant frequencies of ground-state 87Rb and 133Cs atoms in Xe buffer gas are shown to have a relatively large nonlinear dependence on the Xe pressure, presumably because of RbXe or CsXe van der Waals molecules. The nonlinear shifts for Xe are opposite in sign to the previously measured shifts for Ar and Kr, even though all three gases have negative linear shifts. The Xe data show striking discrepancies with the previous theory for nonlinear shifts. Most of this discrepancy is eliminated by accounting for the spin-rotation interaction in addition to the hyperfine-shift interaction in the molecules. To the limit of our experimental accuracy, the shifts of 87Rb and 133Cs in He, Ne, and N2 were linear with pressure.

  7. Study on Fine Structure of Gas Atomized LaNi5-based Alloys

    Institute of Scientific and Technical Information of China (English)

    Hai JING; Hong GUO; Shuguang ZHANG; Zili MA; Shaoming ZHANG

    2003-01-01

    The fine structure of hydrogen storage alloy powders MINi4.3-xCoxMn0.4Al0.3(x=0.75, 0.45, 0.10; MI: La-rich mischmetal) prepared by rapidly solidifying gas atomization was investigated using a Rietveld analysis method. Two setsof CaCu5-type crystal constants were observed in the studied alloys and one set was larger than the other. Withdecreasing powder radius the solidification rate of powder increased, and so did the percentage of a particle partwith larger crystal constants. The reason why there were two sets of crystal constants might be the difference ofsolidification rate between the outside and inside of a particle.

  8. Trapping of Weak Signal Pulses by Soliton and Trajectory Control in a Coherent Atomic Gas

    CERN Document Server

    Chen, Zhiming

    2016-01-01

    We propose a method for trapping weak signal pulses by soliton and realizing its trajectory control via electromagnetically induced transparency (EIT). The system we consider is a cold, coherent atomic gas with a tripod or multipod level configuration. We show that, due to the giant enhancement of Kerr nonlinearity contributed by EIT, several weak signal pulses can be effectively trapped by a soliton and cotravel stably with ultraslow propagating velocity. Furthermore, we demonstrate that the trajectories of the soliton and the trapped signal pulses can be manipulated by using a Stern-Gerlach gradient magnetic field. As a result, the soliton and the trapped signal pulses display a Stern-Gerlach deflection and both of them can bypass an obstacle together. The results predicted here may be used to design all-optical switching at very low light level.

  9. Gas permeation barriers deposited by atmospheric pressure plasma enhanced atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, Lukas, E-mail: lhoffmann@uni-wuppertal.de; Theirich, Detlef; Hasselmann, Tim; Räupke, André; Schlamm, Daniel; Riedl, Thomas, E-mail: t.riedl@uni-wuppertal.de [Institute of Electronic Devices, University of Wuppertal, Rainer-Gruenter-Str. 21, 42119 Wuppertal (Germany)

    2016-01-15

    This paper reports on aluminum oxide (Al{sub 2}O{sub 3}) thin film gas permeation barriers fabricated by atmospheric pressure atomic layer deposition (APPALD) using trimethylaluminum and an Ar/O{sub 2} plasma at moderate temperatures of 80 °C in a flow reactor. The authors demonstrate the ALD growth characteristics of Al{sub 2}O{sub 3} films on silicon and indium tin oxide coated polyethylene terephthalate. The properties of the APPALD-grown layers (refractive index, density, etc.) are compared to that deposited by conventional thermal ALD at low pressures. The films films deposited at atmospheric pressure show water vapor transmission rates as low as 5 × 10{sup −5} gm{sup −2}d{sup −1}.

  10. Increasing of MERARG experimental performances: on-line fission gas release measurement by mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Pontillon, Y.; Capdevila, H.; Clement, S. [CEA, DEN, DEC, SA3C, LAMIR, F-13108 Saint Paul lez Durance, (France); Guigues, E.; Janulyte, A.; Zerega, Y.; Andre, J. [Aix-Marseille Universite, LISA EA 4672, 13397 MARSEILLE cedex 20, (France)

    2015-07-01

    The MERARG device - implemented at the LECASTAR Hot Laboratory, at the CEA Cadarache - allows characterizing nuclear fuels with respect to the behaviour of fission gases during thermal transients representative of normal or off normal operating nuclear power plant conditions. The fuel is heated in order to extract a part or the total gas inventory it contains. Fission Gas Release (FGR) is actually recorded by mean of both on-line gamma spectrometry station and micro gas chromatography. These two devices monitor the quantity and kinetics of fission gas release rate. They only address {sup 85}Kr radioactive isotope and the elemental quantification of Kr, Xe and He (with a relatively low detection limit in the latter case, typically 5-10 ppm). In order to better estimate the basic mechanisms that promote fission gas release from irradiated nuclear fuels, the CEA fuel study department decided to improve its experimental facility by modifying MERARG to extend the studies of gamma emitter fission gases to all gases (including Helium) with a complete isotopic distribution capability. To match these specifications, a Residual Gas Analyser (RGA) has been chosen as mass spectrometer. This paper presents a review of the main aspects of the qualification/calibration phase of the RGA type analyser. In particular, results recorded over three mass ranges 1-10 u, 80-90 u and 120-140 u in the two classical modes of MERARG, i.e. on-line and off-line measurements are discussed. Results obtained from a standard gas bottle show that the quantitative analysis at a few ppm levels can be achieved for all isotopes of Kr and Xe, as well as masses 2 and 4 u. (authors)

  11. Early Science with the Large Millimeter Telescope: COOL BUDHIES I - a pilot study of molecular and atomic gas at z~0.2

    CERN Document Server

    Cybulski, Ryan; Erickson, Neal; De la Luz, Victor; Narayanan, Gopal; Montaña, Alfredo; Sánchez-Argülles, David; Zavala, Jorge A; Zeballos, Milagros; Chung, Aeree; Fernández, Ximena; van Gorkom, Jacqueline; Haines, Chris P; Jaffé, Yara L; Montero-Castaño, María; Poggianti, Bianca M; Verheijen, Marc A W; Yoon, Hyein; Harrington, Kevin; Hughes, David H; Morrison, Glenn E; Schloerb, F Peter; Velazquez, Miguel

    2015-01-01

    An understanding of the mass build-up in galaxies over time necessitates tracing the evolution of cold gas (molecular and atomic) in galaxies. To that end, we have conducted a pilot study called CO Observations with the LMT of the Blind Ultra-Deep H I Environment Survey (COOL BUDHIES). We have observed 23 galaxies in and around the two clusters Abell 2192 (z = 0.188) and Abell 963 (z = 0.206), where 12 are cluster members and 11 are slightly in the foreground or background, using about 28 total hours on the Redshift Search Receiver (RSR) on the Large Millimeter Telescope (LMT) to measure the $^{12}$CO J = 1 --> 0 emission line and obtain molecular gas masses. These new observations provide a unique opportunity to probe both the molecular and atomic components of galaxies as a function of environment beyond the local Universe. For our sample of 23 galaxies, nine have reliable detections (S/N$\\geq$3.6) of the $^{12}$CO line, and another six have marginal detections (2.0 < S/N < 3.6). For the remaining eig...

  12. Evidence for Efimov quantum states in an ultracold gas of caesium atoms.

    Science.gov (United States)

    Kraemer, T; Mark, M; Waldburger, P; Danzl, J G; Chin, C; Engeser, B; Lange, A D; Pilch, K; Jaakkola, A; Nägerl, H-C; Grimm, R

    2006-03-16

    Systems of three interacting particles are notorious for their complex physical behaviour. A landmark theoretical result in few-body quantum physics is Efimov's prediction of a universal set of bound trimer states appearing for three identical bosons with a resonant two-body interaction. Counterintuitively, these states even exist in the absence of a corresponding two-body bound state. Since the formulation of Efimov's problem in the context of nuclear physics 35 years ago, it has attracted great interest in many areas of physics. However, the observation of Efimov quantum states has remained an elusive goal. Here we report the observation of an Efimov resonance in an ultracold gas of caesium atoms. The resonance occurs in the range of large negative two-body scattering lengths, arising from the coupling of three free atoms to an Efimov trimer. Experimentally, we observe its signature as a giant three-body recombination loss when the strength of the two-body interaction is varied. We also detect a minimum in the recombination loss for positive scattering lengths, indicating destructive interference of decay pathways. Our results confirm central theoretical predictions of Efimov physics and represent a starting point with which to explore the universal properties of resonantly interacting few-body systems. While Feshbach resonances have provided the key to control quantum-mechanical interactions on the two-body level, Efimov resonances connect ultracold matter to the world of few-body quantum phenomena.

  13. Laser spectroscopy with nanometric gas cells distance dependence of atom-surface interaction and collisions under confinement

    CERN Document Server

    Hamdi, I; Yarovitski, A; Dutier, G; Maurin, I; Saltiel, S; Li, Y; Lezama, A; Vartapetyan, T; Sarkisyan, D; Gorza, M P; Fichet, M; Bloch, D; Ducloy, M; Hamdi, Ismah\\`{e}ne; Todorov, Petko; Yarovitski, Alexander; Dutier, Gabriel; Maurin, Isabelle; Saltiel, Solomon; Li, Yuanyuan; Lezama, Arturo; Varzhapetyan, Tigran; Sarkisyan, David; Gorza, Marie-Pascale; Fichet, Mich\\`{e}le; Bloch, Daniel; Ducloy, Martial

    2005-01-01

    The high sensitivity of Laser Spectroscopy has made possible the exploration of atomic resonances in newly designed "nanometric" gas cells, whose local thickness varies from 20nm to more than 1000 nm. Following the initial observation of the optical analogous of the coherent Dicke microwave narrowing, the newest prospects include the exploration of long-range atom surface van der Waals interaction with spatial resolution in an unprecedented range of distances, modification of atom dielectric resonant coupling under the influence of the coupling between the two neighbouring dielectric media, and even the possible modification of interatomic collisions processes under the effect of confinement.

  14. The Radio to Infrared Emission of Very High Redshift Gamma-Ray Bursts: Probing Early Star Formation through Molecular and Atomic Absorption Lines

    CERN Document Server

    Inoue, S; Ciardi, B; Inoue, Susumu; Omukai, Kazuyuki; Ciardi, Benedetta

    2005-01-01

    We evaluate the broadband afterglow emission of very high redshift gamma-ray bursts (GRBs) using standard relativistic blastwave models with both forward and reverse shock components. For a broad range of parameters, a generic property for GRBs at redshifts $z \\sim$ 5--30 is that the emission peaks in the millimeter to far-infrared bands with milli-Jansky flux levels, first at a few hours after the burst due to the reverse shock, and then again for several days afterwards with somewhat lower flux due to the forward shock. The radio, submillimeter and infrared continuum emission should be readily detectable out to $z \\ga 30$ by the Atacama Large Millimeter Array (ALMA), Extended Very Large Array (EVLA), Square Kilometer Array (SKA) and other facilities. For relatively bright bursts, spectroscopic measurements of molecular and atomic absorption lines due to ambient protostellar gas may be possible. Utilizing models of primordial protostellar clouds, we show that under certain conditions, appreciable absorption ...

  15. Atomic Hydrogen Gas in Dark-Matter Minihalos and the Compact High Velocity Clouds

    CERN Document Server

    Sternberg, A; Wolfire, M G

    2002-01-01

    We calculate the coupled hydrostatic and ionization structures of pressure-supported gas clouds that are confined by gravitationally dominant dark-matter (DM) mini-halos and by an external bounding pressure provided by a hot medium. We focus on clouds that are photoionized and heated by the present-day background metagalactic field and determine the conditions for the formation of warm (WNM), and multi-phased (CNM/WNM) neutral atomic hydrogen (HI) cores in the DM-dominated clouds. We consider LCDM dark-matter halos, and we compute models for a wide range of halo masses, total cloud gas masses, and external bounding pressures. We present models for the pressure-supported HI structures observed in the Local Group dwarf galaxies Leo A and Sag DIG. We then construct minihalo models for the multi-phased (and low-metallicity) compact high-velocity HI clouds (CHVCs). If the CHVCs are drawn from the same family of halos that successfully reproduce the dwarf galaxy observations, then the CHVCs must be "circumgalactic ...

  16. Gas atomization processing of tin and silicon modified LaNi{sub 5} for nickel-metal hydride battery applications

    Energy Technology Data Exchange (ETDEWEB)

    Ting, J.

    1999-02-12

    Numerous researchers have studied the relevant material properties of so-called AB{sub 5} alloys for battery applications. These studies involved LaNi{sub 5} substituted alloys which were prepared using conventional cast and crush alloying techniques. While valuable to the understanding of metal hydride effects, the previous work nearly ignored the potential for alternative direct powder production methods, like high pressure gas atomization (HPGA). Thus, there is a need to understand the relationship between gas atomization processes, powder particle solidification phases, and hydrogen absorption properties of ultra fine (< 25 {micro}m) atomized powders with high surface area for enhanced battery performance. Concurrently, development of a gas atomization nozzle that is more efficient than all current designs is needed to increase the yield of ultrafine AB{sub 5} alloy powder for further processing advantage. Gas atomization processing of the AB{sub 5} alloys was demonstrated to be effective in producing ultrafine spherical powders that were resilient to hydrogen cycling for the benefit of improving corrosion resistance in battery application. These ultrafine powders benefited from the rapid solidification process by having refined solute segregation in the microstructure of the gas atomized powders which enabled a rapid anneal treatment of the powders. The author has demonstrated the ability to produce high yields of ultrafine powder efficiently and cost effectively, using the new HPGA-III technology. Thus, the potential benefits of processing AB{sub 5} alloys using the new HPGA technology could reduce manufacturing cost of nickel-metal hydride powder. In the near future, the manufacture of AB{sub 5} alloy powders could become a continuous and rapid production process. The economic benefit of an improved AB{sub 5} production process may thereby encourage the use of nickel-metal hydride rechargeable batteries in electrical vehicle applications in the foreseeable

  17. Creation and recovery of a W(111) single atom gas field ion source.

    Science.gov (United States)

    Pitters, Jason L; Urban, Radovan; Wolkow, Robert A

    2012-04-21

    Tungsten single atom tips have been prepared from a single crystal W(111) oriented wire using the chemical assisted field evaporation and etching method. Etching to a single atom tip occurs through a symmetric structure and leads to a predictable last atom unlike etching with polycrystalline tips. The single atom tip formation procedure is shown in an atom by atom removal process. Rebuilds of single atom tips occur on the same crystalline axis as the original tip such that ion emission emanates along a fixed direction for all tip rebuilds. This preparation method could be utilized and developed to prepare single atom tips for ion source development.

  18. Small-scale properties of atomic gas in extended disks of galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Borthakur, Sanchayeeta; Heckman, Timothy M. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Momjian, Emmanuel [National Radio Astronomy Observatory, Socorro, NM 87801 (United States); York, Donald G. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Bowen, David V. [Princeton University Observatory, Peyton Hall, Ivy Lane, Princeton, NJ 08544 (United States); Yun, Min S.; Tripp, Todd M., E-mail: sanch@pha.jhu.edu [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)

    2014-11-01

    We present high-resolution H I 21 cm observations with the Karl G. Jansky Very Large Array for three H I rich galaxies in absorption against radio quasars. Our sample contains six sightlines with impact parameters from 2.6 to 32.4 kpc. We detected a narrow H I absorber of FWHM 1.1 km s{sup –1} at 444.5 km s{sup –1} toward SDSS J122106.854+454852.16 probing the dwarf galaxy UCG 7408 at an impact parameter of 2.8 kpc. The absorption feature was barely resolved and its width corresponds to a maximum kinetic temperature, T{sub k} ≈ 26 K. We estimate a limiting peak optical depth of 1.37 and a column density of 6 × 10{sup 19} cm{sup –2}. The physical extent of the absorber is 0.04 kpc{sup 2} and covers ∼25%-30% of the background source. A comparison between the emission and absorption strengths suggests the cold-to-total H I column density in the absorber is ∼30%. Folding in the covering fraction, the cold-to-total H I mass is ∼10%. This suggest that condensation of warm H I (T{sub s} ∼ 1000 K) to cold phase (T{sub s} < 100 K) is suppressed in UGC 7408. The unusually low temperature of the H I absorber also indicates inefficiency in condensation of atomic gas into molecular gas. The suppression in condensation is likely to be the result of low metal content in this galaxy. The same process might explain the low efficiency of star formation in dwarf galaxies despite their huge gas reservoirs. We report the non-detection of H I in absorption in five other sightlines. This indicates that either the cold gas distribution is highly patchy or the gas is much warmer (T{sub s} > 1000 K) toward these sightlines.

  19. Herschel observations of extended atomic gas in the core of the Perseus cluster

    CERN Document Server

    Mittal, Rupal; Ferland, Gary J; Edge, Alastair C; O'Dea, Christopher P; Baum, Stefi A; Whelan, John T; Johnstone, Roderick M; Combes, Francoise; Salome, Philippe; Fabian, Andy C; Tremblay, Grant R; Donahue, Megan; Russell, Helen

    2012-01-01

    We present Herschel observations of the core of the Perseus cluster of galaxies. The brightest cluster galaxy, NGC 1275, is surrounded by a network of filaments previously imaged extensively in H{\\alpha} and CO. In this work, we report detections of FIR lines with Herschel. All but one of the lines are spatially extended, with the [CII] line emission extending up to 25 kpc from the core. There is spatial and kinematical correlation among [CII], H{\\alpha} and CO, which gives us confidence to model the different components of the gas with a common heating model. With the help of FIR continuum Herschel measurements, together with a suite of coeval radio, submm and infrared data, we performed a SED fitting of NGC 1275 using a model that contains contributions from dust emission as well as synchrotron AGN emission. The data indicate a low dust emissivity index, beta ~ 1, a total dust mass close to 10^7 solar mass, a cold dust component with temperature 38 \\pm 2 K and a warm dust component with temperature of 116 \\...

  20. Gas Pipelines, LP and LNG, Gas transmission line work provided to AIMS from Kansas Gas Service. Data is limited to CUE (Collaborative Utility Exchange) Participants and subcontractors of them., Published in 2004, Johnson County AIMS.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Gas Pipelines, LP and LNG dataset, was produced all or in part from Other information as of 2004. It is described as 'Gas transmission line work provided to...

  1. The Properties of Lyman Alpha Nebulae: Gas Kinematics from Non-resonant Lines

    CERN Document Server

    Yang, Yujin; Jahnke, Knud; Davé, Romeel

    2014-01-01

    [Abridged] With VLT/X-shooter, we obtain optical and NIR spectra of six Ly-alpha blobs at z~2.3. Using three measures --- the velocity offset between the Lya line and the non-resonant [OIII] or H-alpha line (Dv_Lya), the offset of stacked interstellar metal absorption lines, and the spectrally-resolved [OIII] line profile --- we study the kinematics of gas along the line of sight to galaxies within each blob center. These three indicators generally agree in velocity and direction, and are consistent with a simple picture in which the gas is stationary or slowly outflowing at a few hundred km/s from the embedded galaxies. The absence of stronger outflows is not a projection effect: the covering fraction for our sample is limited to <1/8 (13%). The outflow velocities exclude models in which star formation or AGN produce "super" or "hyper" winds of up to ~1000km/s. The Dv_Lya offsets here are smaller than typical of LBGs, but similar to those of compact LAEs. The latter suggests that outflow speed cannot be a...

  2. The contact line behaviour of solid-liquid-gas diffuse-interface models

    CERN Document Server

    Sibley, David N; Savva, Nikos; Kalliadasis, Serafim

    2013-01-01

    A solid-liquid-gas moving contact line is considered through a diffuse-interface model with the classical boundary condition of no-slip at the solid surface. Examination of the asymptotic behaviour as the contact line is approached shows that the relaxation of the classical model of a sharp liquid-gas interface, whilst retaining the no-slip condition, resolves the stress and pressure singularities associated with the moving contact line problem while the fluid velocity is well defined (not multi-valued). The moving contact line behaviour is analysed for a general problem relevant for any density dependent dynamic viscosity and volume viscosity, and for general microscopic contact angle and double well free-energy forms. Away from the contact line, analysis of the diffuse-interface model shows that the Navier--Stokes equations and classical interfacial boundary conditions are obtained at leading order in the sharp-interface limit, justifying the creeping flow problem imposed in an intermediate region in the se...

  3. Atomic carbon as a tracer of molecular gas in high-redshift galaxies: perspectives for ALMA

    CERN Document Server

    Tomassetti, Matteo; Romano-Diaz, Emilio; Ludlow, Aaron D; Papadopoulos, Padelis P

    2014-01-01

    We use a high-resolution simulation that tracks the non-equilibrium abundance of molecular hydrogen, H2, within a massive high-redshift galaxy to produce mock ALMA maps of the fine-structure lines of atomic carbon CI 1-0 and CI 2-1. Inspired by recent observational and theoretical work, we assume that CI is thoroughly mixed in giant molecular clouds and demonstrate that its emission is an excellent proxy for H2. The entire H2 mass of a galaxy at redshift z<4 can be detected using a compact interferometric configuration with a large synthesized beam (that does not resolve the target galaxy) in less than 1 hour of integration time. Low-resolution imaging of the CI lines (in which the target galaxy is resolved into 3-4 beams) will detect nearly 50-60 per cent of the molecular hydrogen in less than 12 hours. In this case, the data cube also provides valuable information regarding the dynamical state of the galaxy. We conclude that ALMA observations of the CI 1-0 and 2-1 emission will widely extend the interval...

  4. Effect of closed-couple gas atomization pressure on the performances of Al-20Sn-1 Cu powders

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xinming; XU Jun; ZHU Xuexin; ZHANG Shaoming

    2008-01-01

    Al-20Sn-1 Cu powders were prepared by gas atomization in an argon atmosphere with atomizing pressures of 1.1 and 1.6 MPa.The characteristics of the powders are determined by means of dry sieving,scanning electron microscopy (SEM),optical microscopy (OM),and X-ray diffractometry (XRD).The results show that the powders exhibit a bimodal size distribution and a higher gas pressure results in a broad size distribution.All particles in both cases are spherical or nearly spherical and satellites form on the surface of coarse particles.Dendritic and cellular structures coexist in the particle.With decreasing particle diameter,the secondary dendrite arm spacing (SDAS) decreases and the cooling rate increases.The particles processed under high gas atomization pressure (1.6 MPa) exhibit a lower SDAS value and a higher cooling rate than those of the same size under low gas atomization pressure (1.1 MPa).The XRD results show that the Sn content increases with decreasing particle size.

  5. Lateral gas phase diffusion length of boron atoms over Si/B surfaces during CVD of pure boron layers

    NARCIS (Netherlands)

    Mohammadi, V.; Nihtianov, S.

    2016-01-01

    The lateral gas phase diffusion length of boron atoms, LB, along silicon and boron surfaces during chemical vapor deposition(CVD) using diborane (B2H6) is reported. The value of LB is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and co

  6. Atomic layer deposition of Ru from CpRu(CO)(2)Et using O-2 gas and O-2 plasma

    NARCIS (Netherlands)

    Leick, N.; Verkuijlen, R. O. F.; Lamagna, L.; Langereis, E.; Rushworth, S.; Roozeboom, F.; M. C. M. van de Sanden,; Kessels, W. M. M.

    2011-01-01

    The metalorganic precursor cyclopentadienylethyl(dicarbonyl)ruthenium (CpRu(CO)(2)Et) was used to develop an atomic layer deposition (ALD) process for ruthenium. O-2 gas and O-2 plasma were employed as reactants. For both processes, thermal and plasma-assisted ALD, a relatively high growth-per-cycle

  7. The Use of Gas Chromatography and Mass Spectrometry to Introduce General Chemistry Students to Percent Mass and Atomic Mass Calculations

    Science.gov (United States)

    Pfennig, Brian W.; Schaefer, Amy K.

    2011-01-01

    A general chemistry laboratory experiment is described that introduces students to instrumental analysis using gas chromatography-mass spectrometry (GC-MS), while simultaneously reinforcing the concepts of mass percent and the calculation of atomic mass. Working in small groups, students use the GC to separate and quantify the percent composition…

  8. Lining for high temperature gas turbines. Auskleidung fuer Hochtemperatur-Gasturbinen

    Energy Technology Data Exchange (ETDEWEB)

    Bechtel, P.; Heckel, J.

    1986-06-26

    A lining is described for high temperature gas turbines, where a thermally insulating layer of a ceramic material is applied on the side of the turbine casing towards the high temperature. In order to insulate the heat which occurs at the very high process temperatures in this gas turbine plant, it is proposed that a first layer of microporous material containing mainly silica should be applied on the inner wall of the casing, that a second layer of ceramic fibres should be applied on this first layer that a binding layer of a fibre mat consisting of Al/sub 2/O/sub 3/ and SiO/sub 2/ and possibly with the addition of Cr/sub 2/O/sub 3/ should be provided between the turbine casing and the first layer and between the first and second layer, and that a lining layer of heat-resistant high quality steel is applied on this second layer.

  9. On-line monitoring of dissolved gas-in-oil with FTIR spectra

    Institute of Scientific and Technical Information of China (English)

    Xianyong Liu; Yunluo Liu; Li Yue

    2003-01-01

    To overcome the disadvantages of conventional DGA (dissolved gas-in-oil) analysis using gas chromatography and other electrochemical sensors, initial researches were completed to realize on-line monitoring of dissolved gas-in-oil of power transformers using FTIR (Fourier Transform InfraRed) spectroscopy. Gas cell method is used to determine the characteristic absorption peaks of each diagnostic gas; simple and novel devices and procedures were designed in order to get measurable samples and spectra of mixed diagnostic gases with known concentration are taken using long optical path gas cell. The range of wavelength is estimated to be 3.0-13.9 μm from experimental spectra data. Hence the corresponding sampling frequency range should be in 536-4288 Hz and usable optical materials are suggested. It is concluded that a resolution of 10 cm-1 may well satisfy the monitoring of all diagnostic gases and water content except hydrogen, and the lowest detection limit may be as low as 2×l0-8 to acetylene with a 2.4-meter-long optical length.

  10. CHARACTERIZATION OF DWPF MELTER OFF-GAS QUENCHER AND STEAM ATOMIZED SCRUBBER DEPOSIT SAMPLES

    Energy Technology Data Exchange (ETDEWEB)

    Zeigler, K; Ned Bibler, N

    2007-06-06

    This report summarizes the results from the characterization of deposits from the inlets of the primary off-gas Quencher and Steam Atomized Scrubber (SAS) in the Defense Waste Processing Facility (DWPF), as requested by a technical assistance request. DWPF requested elemental analysis and compound identification to help determine the potential causes for the substance formation. This information will be fed into Savannah River National Laboratory modeling programs to determine if there is a way to decrease the formation of the deposits. The general approach to the characterization of these samples included x-ray diffraction (XRD), scanning electron microscopy (SEM), and chemical analysis. The following conclusions are drawn from the analytical results found in this report: (1) The deposits are not high level waste glass from the DWPF melt pool based on comparison of the compositions of deposits to the composition of a sample of glass taken from the pour stream of the melter during processing of Sludge Batch 3. (2) Chemical composition results suggest that the deposits are probably a combination of sludge and frit particles entrained in the off-gas. (3) Gamma emitters, such as Co-60, Cs-137, Eu-154, Am-241, and Am-243 were detected in both the Quencher and SAS samples with Cs-137 having the highest concentration of the gamma emitters. (4) No evidence existed for accumulation of fissile material (U-233, U-235, and Pu-239) relative to Fe in either deposit. (5) XRD results indicated both samples were primarily amorphorous and contained some crystals of the iron oxides, hematite and magnetite (Fe{sub 2}O{sub 3} and Fe(Fe{sub 2}O{sub 4})), along with sodium nitrate (NaNO{sub 3}). The other main crystalline compound in the SAS deposit was mercurous chloride. The main crystalline compound in the Quencher deposit was a uranium oxide compound. These are all sludge components. (6) SEM analysis of the Quencher deposit revealed crystalline uranium compounds within the sample

  11. Gas atomized precursor alloy powder for oxide dispersion strengthened ferritic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Rieken, Joel [Iowa State Univ., Ames, IA (United States)

    2011-12-13

    Gas atomization reaction synthesis (GARS) was employed as a simplified method for producing precursor powders for oxide dispersion strengthened (ODS) ferritic stainless steels (e.g., Fe-Cr-Y-(Ti,Hf)-O), departing from the conventional mechanical alloying (MA) process. During GARS processing a reactive atomization gas (i.e., Ar-O2) was used to oxidize the powder surfaces during primary break-up and rapid solidification of the molten alloy. This resulted in envelopment of the powders by an ultra-thin (t < 150 nm) metastable Cr-enriched oxide layer that was used as a vehicle for solid-state transport of O into the consolidated microstructure. In an attempt to better understand the kinetics of this GARS reaction, theoretical cooling curves for the atomized droplets were calculated and used to establish an oxidation model for this process. Subsequent elevated temperature heat treatments, which were derived from Rhines pack measurements using an internal oxidation model, were used to promote thermodynamically driven O exchange reactions between trapped films of the initial Cr-enriched surface oxide and internal Y-enriched intermetallic precipitates. This novel microstructural evolution process resulted in the successful formation of nano-metric Y-enriched dispersoids, as confirmed using high energy X-ray diffraction and transmission electron microscopy (TEM), equivalent to conventional ODS alloys from MA powders. The thermal stability of these Y-enriched dispersoids was evaluated using high temperature (1200°C) annealing treatments ranging from 2.5 to 1,000 hrs of exposure. In a further departure from current ODS practice, replacing Ti with additions of Hf appeared to improve the Y-enriched dispersoid thermal stability by means of crystal structure modification. Additionally, the spatial distribution of the dispersoids was found to depend strongly on the original rapidly solidified microstructure. To exploit this, ODS microstructures were engineered from

  12. The JCMT Nearby Galaxies Legacy Survey III: Comparisons of cold dust, polycyclic aromatic hydrocarbons, molecular gas, and atomic gas in NGC 2403

    CERN Document Server

    Bendo, G J; Warren, B E; Brinks, E; Butner, H M; Chanial, P; Clements, D L; Courteau, S; Irwin, J; Israel, F P; Knapen, J H; Leech, J; Matthews, H E; Muehle, S; Petitpas, G; Serjeant, S; Tan, B K; Tilanus, R P J; Usero, A; Vaccari, M; van der Werf, P; Vlahakis, C; Wiegert, T; Zhu, M

    2009-01-01

    We used 3.6, 8.0, 70, 160 micron Spitzer Space Telescope data, James Clerk Maxwell Telescope HARP-B CO J=(3-2) data, National Radio Astronomy Observatory 12 meter telescope CO J=(1-0) data, and Very Large Array HI data to investigate the relations among PAHs, cold (~20 K) dust, molecular gas, and atomic gas within NGC 2403, an SABcd galaxy at a distance of 3.13 Mpc. The dust surface density is mainly a function of the total (atomic and molecular) gas surface density and galactocentric radius. The gas-to-dust ratio monotonically increases with radius, varying from ~100 in the nucleus to ~400 at 5.5 kpc. The slope of the gas-to-dust ratio is close to that of the oxygen abundance, suggesting that metallicity strongly affects the gas-to-dust ratio within this galaxy. The exponential scale length of the radial profile for the CO J=(3-2) emission is statistically identical to the scale length for the stellar continuum-subtracted 8 micron (PAH 8 micron) emission. However, CO J=(3-2) and PAH 8 micron surface brightne...

  13. Recent Studies of Proton Drip-Line Nuclei Using the Berkeley Gas-Filled Separator

    Energy Technology Data Exchange (ETDEWEB)

    Rowe, M.W.; Batchelder, J.C.; Ninov, V.; Gregorich, K.E.; Toth, K.S.; Bingham, C.R.; Piechaczek, A.; Xu, X.J.; Powell, J.; Joosten, R.; Cerny, J.

    1999-10-07

    The Berkeley Gas-filled Separator provides new research opportunities at Lawrence Berkeley National Laboratory's X-Inch Cyclotron. The use of this apparatus for the study of proton drip-line nuclides is discussed. Preliminary results of {sup 78}Kr bombardments of {sup 102}Pd targets at mid-target energies of 360, 375 and 385 MeV are presented. Improvements planned partially as a result of this measurement are also discussed.

  14. Parametric Limits of Efficient Use of a Centrifugal Water Atomizer in Contact Waste-Gas Heat-Utilization Units

    Science.gov (United States)

    Bezrodnyi, M. K.; Rachinskii, A. Yu.; Barabash, P. A.; Goliyad, N. N.

    2016-07-01

    The relation for the limiting temperature of water heating in a contact gas-droplet-type apparatus with a centrifugal atomizer has been determined experimentally in relation to the conditions of utilization of heat of power plant waste-gases. Investigations were carried out in the range of excess water pressures in front of the atomizer 0.2-0.6 MPa and of the volume fraction of steam in the vapor-gas mixture at the inlet of the apparatus from 0.02 to 0.45. The possibility of using the obtained dependence for calculating the limiting values of the vapor-gas flow parameters that limit the range of efficient operation of the contact apparatus with steam condensation and in the absence of heated liquid droplet evaporation is shown.

  15. Coherent and non coherent atom optics experiment with an ultra-narrow beam of metastable rare gas atoms; Experiences d'optique atomique coherente ou non avec un jet superfin d'atomes metastables de gaz rares

    Energy Technology Data Exchange (ETDEWEB)

    Grucker, J

    2007-12-15

    In this thesis, we present a new type of atomic source: an ultra-narrow beam of metastable atoms produced by resonant metastability exchange inside a supersonic beam of rare gas atoms. We used the coherence properties of this beam to observe the diffraction of metastable helium, argon and neon atoms by a nano-transmission grating and by micro-reflection-gratings. Then, we evidenced transitions between Zeeman sublevels of neon metastable {sup 3}P{sub 2} state due to the quadrupolar part of Van der Waals potential. After we showed experimental proofs of the observation of this phenomenon, we calculated the transition probabilities in the Landau - Zener model. We discussed the interest of Van der Waals - Zeeman transitions for atom interferometry. Last, we described the Zeeman cooling of the supersonic metastable argon beam ({sup 3}P{sub 2}). We have succeeded in slowing down atoms to speeds below 100 m/s. We gave experimental details and showed the first time-of-flight measurements of slowed atoms.

  16. Contact line motion in confined liquid–gas systems: Slip versus phase transition

    KAUST Repository

    Xu, Xinpeng

    2010-11-30

    In two-phase flows, the interface intervening between the two fluid phases intersects the solid wall at the contact line. A classical problem in continuum fluid mechanics is the incompatibility between the moving contact line and the no-slip boundary condition, as the latter leads to a nonintegrable stress singularity. Recently, various diffuse-interface models have been proposed to explain the contact line motion using mechanisms missing from the sharp-interface treatments in fluid mechanics. In one-component two-phase (liquid–gas) systems, the contact line can move through the mass transport across the interface while in two-component (binary) fluids, the contact line can move through diffusive transport across the interface. While these mechanisms alone suffice to remove the stress singularity, the role of fluid slip at solid surface needs to be taken into account as well. In this paper, we apply the diffuse-interface modeling to the study of contact line motion in one-component liquid–gas systems, with the fluid slip fully taken into account. The dynamic van der Waals theory has been presented for one-component fluids, capable of describing the two-phase hydrodynamics involving the liquid–gas transition [A. Onuki, Phys. Rev. E 75, 036304 (2007)]. This theory assumes the local equilibrium condition at the solid surface for density and also the no-slip boundary condition for velocity. We use its hydrodynamicequations to describe the continuum hydrodynamics in the bulk region and derive the more general boundary conditions by introducing additional dissipative processes at the fluid–solid interface. The positive definiteness of entropy production rate is the guiding principle of our derivation. Numerical simulations based on a finite-difference algorithm have been carried out to investigate the dynamic effects of the newly derived boundary conditions, showing that the contact line can move through both phase transition and slip, with their relative

  17. On the influence of the internal structure of the atom on Bose-Einstein condensation in an ideal gas of hydrogenlike atoms

    Science.gov (United States)

    Slyusarenko, Yu. V.; Sotnikov, A. G.

    2007-01-01

    The features of Bose condensation in an equilibrium ideal gas consisting of two types of charged fermions and their bound states—hydrogenlike atoms—in the presence of equilibrium between the photons and matter are investigated. It is shown that under such conditions the main influence on the Bose-Einstein condensation comes from the existence of levels concerned with the hyperfine splitting of the ground state of the hydrogenlike atom. The critical temperature and condensate density as functions of magnetic field are determined by considering effects due to the additional splitting of the levels of the hyperfine structure of the ground state in an external uniform static magnetic field (the Zeeman and Paschen-Back effects). It is found that under conditions of total statistical equilibrium in the system, a condensate is formed only by atoms found in the lowest energy state. It is shown that in the absence of equilibrium between radiation and matter, in the region of ultralow temperatures and low densities, the system can be treated as a multicomponent ideal gas of hydrogenlike atoms. The existence of a hierarchy of individual transition temperatures of each of the samples to the state with Bose-Einstein condensation is established. Expressions are found for the critical temperatures and number densities of particles in the condensate for each of the system components.

  18. NLTE analysis of Sr lines in spectra of late-type stars with new R-matrix atomic data

    CERN Document Server

    Bergemann, M; Bautista, M; Ruchti, G

    2012-01-01

    We investigate statistical equilibrium of neutral and singly-ionized strontium in late-type stellar atmospheres. Particular attention is given to the completeness of the model atom, which includes new energy levels, transition probabilities, photoionization and electron-impact excitation cross-sections computed with the R-matrix method. The NLTE model is applied to the analysis of Sr I and Sr II lines in the spectra of the Sun, Procyon, Arcturus, and HD 122563, showing a significant improvement in the ionization balance compared to LTE line formation calculations, which predict abundance discrepancies of up to 0.5 dex. The solar Sr abundance is log A = 2.93 \\pm 0.04 dex, in agreement with the meteorites. A grid of NLTE abundance corrections for Sr I and Sr II lines covering a large range of stellar parameters is presented.

  19. Absorption-Line Probes of Gas and Dust in Galactic Superwinds

    CERN Document Server

    Heckman, T M; Strickland, D K; Armus, L; Heckman, Timothy M.; Lehnert, Matthew D.; Strickland, David K.; Armus, Lee

    2000-01-01

    We discuss moderate resolution spectra of the NaD absorption-line in a sampleof 32 far-IR-bright starburst galaxies. In 18 cases, the line is producedprimarily by interstellar gas, and in 12 of these it is blueshifted by over 100km/s relative to the galaxy systemic velocity. The absorption-line profiles inthese outflow sources span the range from near the galaxy systemic velocity toa maximum blueshift of 400 to 600 km/s. The outflows occur in galaxiessystematically viewed more nearly face-on than the others. We therefore arguethat the absorbing material consists of ambient interstellar gas acceleratedalong the minor axis of the galaxy by a hot starburst-driven superwind. The NaDlines are optically-thick, but indirect arguments imply total Hydrogen columndensities of N_H = few X 10^{21} cm^{-2}. This implies that the superwind isexpelling matter at a rate comparable to the star-formation rate. Thisoutflowing material is very dusty: we find a strong correlation between thedepth of the NaD profile and the line-o...

  20. Comments on alternative calculations of the broadening of spectral lines of neutral sodium by H-atom collisions

    CERN Document Server

    Barklem, P S

    2001-01-01

    With the exception of the sodium D-lines recent calculations of line broadening cross-sections for several multiplets of sodium by Leininger et al (2000) are in substantial disagreement with cross-sections interpolated from the tables of Anstee and O'Mara (1995) and Barklem and O'Mara (1997). The discrepancy is as large as a factor of three for the 3p-4d multiplet. The two theories are tested by using the results of each to synthesize lines in the solar spectrum. It is found that generally the data from the theory of Anstee, Barklem and O'Mara produce the best match to the observed solar spectrum. It is found, using a simple model for reflection of the optical electron by the potential barrier between the two atoms, that the reflection coefficient is too large for avoided crossings with the upper states of subordinate lines to contribute to line broadening, supporting the neglect of avoided ionic crossings by Anstee, Barklem and O'Mara for these lines. The large discrepancies between the two sets of calculati...

  1. Hydrogen in diffuse molecular clouds in the Milky Way. Atomic column densities and molecular fraction along prominent lines of sight

    Science.gov (United States)

    Winkel, B.; Wiesemeyer, H.; Menten, K. M.; Sato, M.; Brunthaler, A.; Wyrowski, F.; Neufeld, D.; Gerin, M.; Indriolo, N.

    2017-03-01

    Context. Recent submillimeter and far-infrared wavelength observations of absorption in the rotational ground-state lines of various simple molecules against distant Galactic continuum sources have opened the possibility of studying the chemistry of diffuse molecular clouds throughout the Milky Way. In order to calculate abundances, the column densities of molecular and atomic hydrogen, H i, must be known. Aims: We aim at determining the atomic hydrogen column densities for diffuse clouds located on the sight lines toward a sample of prominent high-mass star-forming regions that were intensely studied with the HIFI instrument onboard Herschel. Methods: Based on Jansky Very Large Array data, we employ the 21 cm H i absorption-line technique to construct profiles of the H i opacity versus radial velocity toward our target sources. These profiles are combined with lower resolution archival data of extended H i emission to calculate the H i column densities of the individual clouds along the sight lines. We employ Bayesian inference to estimate the uncertainties of the derived quantities. Results: Our study delivers reliable estimates of the atomic hydrogen column density for a large number of diffuse molecular clouds at various Galactocentric distances. Together with column densities of molecular hydrogen derived from its surrogates observed with HIFI, the measurements can be used to characterize the clouds and investigate the dependence of their chemistry on the molecular fraction, for example. The data sets are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/600/A2

  2. Investigation of the on-axis atom number density in the supersonic gas jet under high gas backing pressure by simulation

    Directory of Open Access Journals (Sweden)

    Guanglong Chen

    2015-10-01

    Full Text Available The supersonic gas jets from conical nozzles are simulated using 2D model. The on-axis atom number density in gas jet is investigated in detail by comparing the simulated densities with the idealized densities of straight streamline model in scaling laws. It is found that the density is generally lower than the idealized one and the deviation between them is mainly dependent on the opening angle of conical nozzle, the nozzle length and the gas backing pressure. The density deviation is then used to discuss the deviation of the equivalent diameter of a conical nozzle from the idealized deq in scaling laws. The investigation on the lateral expansion of gas jet indicates the lateral expansion could be responsible for the behavior of the density deviation. These results could be useful for the estimation of cluster size and the understanding of experimental results in laser-cluster interaction experiments.

  3. Narrow-line magneto-optical trap for erbium: Simple approach for a complex atom

    CERN Document Server

    Frisch, A; Mark, M; Rietzler, A; Schindler, J; Zupanic, E; Grimm, R; Ferlaino, F

    2012-01-01

    We report on the experimental realization of a robust and efficient magneto-optical trap for erbium atoms, based on a narrow cooling transition at 583nm. We observe up to $N=2 \\times 10^{8}$ atoms at a temperature of about $T=15 \\mu K$. This simple scheme provides better starting conditions for direct loading of dipole traps as compared to approaches based on the strong cooling transition alone, or on a combination of a strong and a narrow kHz transition. Our results on Er point to a general, simple and efficient approach to laser cool samples of other lanthanide atoms (Ho, Dy, and Tm) for the production of quantum-degenerate samples.

  4. Capture dynamics in collisions between fullerene ions and rare gas atoms

    Science.gov (United States)

    Campbell, E. E. B.; Ehlich, R.; Heusler, G.; Knospe, O.; Sprang, H.

    1998-12-01

    The collision energy dependence of capture in collisions between C 60+ ions and small rare gas atoms (He, Ne) is studied in detail and compared with the results of classical molecular dynamics simulations. Additional insight is obtained on the dynamics of the collisions by also studying the kinetic energy loss of the projectile ions. Two capture mechanisms are found for He collisions: penetration of a six-membered ring with no significant cage distortion and scattering from a C 2 unit followed by deflection inside the cage. Good agreement is found with the simulations. Ne capture appears to be mainly the product of collisions with ring-structures on the cage followed by bond-breaking and insertion via a window mechanism. The very low threshold energy for Ne capture by fullerene ions (10 eV), reported previously, is attributed to the presence of highly excited, deformed fullerene ions in the beam. A second, higher threshold is found which is in better agreement with other experiments reported in the literature. The simulations of the Ne collisions do not give such good agreement as the He simulations. We attribute this to a too low value of the screening parameter used in the Ne-C potential.

  5. Spark Plasma Sintering of a Gas Atomized Al7075 Alloy: Microstructure and Properties

    Directory of Open Access Journals (Sweden)

    Orsolya Molnárová

    2016-12-01

    Full Text Available The powder of an Al7075 alloy was prepared by gas atomization. A combination of cellular, columnar, and equiaxed dendritic-like morphology was observed in individual powder particles with continuous layers of intermetallic phases along boundaries. The cells are separated predominantly by high-angle boundaries, the areas with dendritic-like morphology usually have a similar crystallographic orientation. Spark plasma sintering resulted in a fully dense material with a microstructure similar to that of the powder material. The continuous layers of intermetallic phases are replaced by individual particles located along internal boundaries, coarse particles are formed at the surface of original powder particles. Microhardness measurements revealed both artificial and natural ageing behavior similar to that observed in ingot metallurgy material. The minimum microhardness of 81 HV, observed in the sample annealed at 300 °C, reflects the presence of coarse particles. The peak microhardness of 160 HV was observed in the sample annealed at 500 °C and then aged at room temperature. Compression tests confirmed high strength combined with sufficient plasticity. Annealing even at 500 °C does not significantly influence the distribution of grain sizes—about 45% of the area is occupied by grains with the size below 10 µm.

  6. Outflowing atomic and molecular gas at $z \\sim 0.67$ towards 1504+377

    CERN Document Server

    Kanekar, Nissim

    2007-01-01

    We report the detection of OH 1667 MHz and wide HI 21cm absorption at $z \\sim 0.67$ towards the red quasar 1504+377, with the Green Bank Telescope and the Giant Metrewave Radio Telescope. The HI 21cm absorption extends over a velocity range of $\\sim 600$ km/s blueward of the quasar redshift ($z=0.674$), with the new OH 1667 MHz absorption component at $\\sim -430$ \\kms, nearly coincident with earlier detections of mm-wave absorption at $z \\sim 0.6715$. The atomic and molecular absorption appear to arise from a fast gas outflow from the quasar, with a mass outflow rate ${\\dot M} \\sim 12 M_\\odot$ yr$^{-1}$ and a molecular hydrogen fraction $f_{\\rm H_2} \\equiv (N_{\\rm H_2}/N_{\\rm HI}) \\sim 0.2$. The radio structure of 1504+377 is consistent with the outflow arising due to a jet-cloud interaction, followed by rapid cooling of the cloud material. The observed ratio of HCO$^+$ to OH column densities is $\\sim 20$ times higher than typical values in Galactic and high-$z$ absorbers. This could arise due to small-scale ...

  7. An $\\epsilon$-pseudoclassical Model for Quantum Resonances in a Periodically Laser-Driven Dilute Atomic Gas

    CERN Document Server

    Beswick, Benjamin T; Gardiner, Simon A; Hughes, Ifan G; Andersen, Mikkel F; Daszuta, Boris

    2016-01-01

    Atom interferometers are a useful tool for precision measurements of fundamental physical phenomena, ranging from local gravitational field strength to the atomic fine structure constant. In such experiments, it is desirable to implement a high momentum transfer "beam-splitter," which may be achieved by inducing quantum resonance in a finite-temperature laser-driven atomic gas. We use Monte Carlo simulations to investigate these quantum resonances in the regime where the gas receives laser pulses of finite duration, and demonstrate that an $\\epsilon$-classical model for the dynamics of the gas atoms is capable of reproducing quantum resonant behavior for both zero-temperature and finite-temperature non-interacting gases. We show that this model agrees well with the fully quantum treatment of the system over a time-scale set by the choice of experimental parameters. We also show that this model is capable of correctly treating the time-reversal mechanism necessary for implementing an interferometer with this p...

  8. Interaction of gas phase atomic hydrogen with Pt(111): Direct evidence for the formation of bulk hydrogen species

    Institute of Scientific and Technical Information of China (English)

    JIANG ZhiQuan; HUANG WeiXin; BAO XinHe

    2007-01-01

    Employing hot tungsten filament to thermal dissociate molecular hydrogen, we generated gas phase atomic hydrogen under ultra-high vacuum (UHV) conditions and investigated its interaction with Pt(111) surface. Thermal desorption spectroscopy (TDS) results demonstrate that adsorption of molecular hydrogen on Pt(111) forms surface Had species whereas adsorption of atomic hydrogen forms not only surface Had species but also bulk Had species. Bulk Had species is more thermal-unstable than surface Had species on Pt(111), suggesting that bulk Had species is more energetic. This kind of weakly- adsorbed bulk Had species might be the active hydrogen species in the Pt-catalyzed hydrogenation reactions.

  9. Gaia-ESO Survey: Gas dynamics in the Carina nebula through optical emission lines

    Science.gov (United States)

    Damiani, F.; Bonito, R.; Magrini, L.; Prisinzano, L.; Mapelli, M.; Micela, G.; Kalari, V.; Maíz Apellániz, J.; Gilmore, G.; Randich, S.; Alfaro, E.; Flaccomio, E.; Koposov, S.; Klutsch, A.; Lanzafame, A. C.; Pancino, E.; Sacco, G. G.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Franciosini, E.; Hourihane, A.; Lardo, C.; Lewis, J.; Monaco, L.; Morbidelli, L.; Worley, C.; Zaggia, S.; Zwitter, T.; Dorda, R.

    2016-06-01

    Aims: We present observations from the Gaia-ESO Survey in the lines of Hα, [N II], [S II], and He I of nebular emission in the central part of the Carina nebula. Methods: We investigate the properties of the two already known kinematic components (approaching and receding), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV >50 km s-1) gas emission. Results: We show that gas giving rise to Hα and He I emission is dynamically well correlated with but not identical to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arise from several distinct shell-like expanding regions, the most evident found around η Car, the Trumpler 14 core, and the star WR25. These "shells" are non-spherical and show distortions probably caused by collisions with other shells or colder, higher-density gas. Some of them are also partially obscured by foreground dust lanes, while very little dust is found in their interior. Preferential directions, parallel to the dark dust lanes, are found in the shell geometries and physical properties, probably related to strong density gradients in the studied region. We also find evidence that the ionizing flux emerging from η Car and the surrounding Homunculus nebula varies with polar angle. The high-velocity components in the wings of Hα are found to arise from expanding dust reflecting the η Car spectrum. Based on observations collected with the FLAMES spectrograph at VLT/UT2 telescope (Paranal Observatory, ESO, Chile), for the Gaia-ESO Large Public Survey (program 188.B-3002).Full Tables 1-3 are only available at the CDS via anonymous ftp to http

  10. Snow Lines in Gas Rich Protoplanetary Disks and the Delivery of Volatiles to Planetary Surfaces

    Science.gov (United States)

    Blake, Geoffrey A.

    2016-06-01

    Compared to the Sun and to the gas+dust composition of the interstellar medium from which the solar system formed, the Carbon and Nitrogen content of the bulk silicate Earth (mantle+hydrosphere+atmosphere) is reduced by several orders of magnitude, relative to Silicon. Evidence from primitive bodies as a function of distance from the Sun suggests that at least part of this depletion must occur early in the process of planetesimal assembly. With combined infrared and (sub)mm observations such as those enabled by ground-based 8-10m class telescopes (and in future the James Webb Space Telescope) and the Atacama Large Millimeter Array (ALMA), we can now examine the principal volatile reservoirs of gas rich disks as a function position within the disk and evolutionary state. Key to these studies is the concept of condensation fronts, or 'snow lines,' in disks - locations at which key volatiles such as water, carbon monoxide, or nitrogen first condense from the gas. This talk will review the observational characterization of snow lines in protoplanetary disks, especially recent ALMA observations, and highlight the laboratory astrophysics studies and theoretical investigations that are needed to tie the observational results to the delivery of volatiles to planetary surfaces in the habitable zones around Sun-like stars.

  11. Performance of sheath electric field measurement by saturation spectroscopy in Balmer-α line of atomic hydrogen

    Science.gov (United States)

    Nishiyama, Shusuke; Katayama, Kento; Nakano, Haruhisa; Goto, Motoshi; Sasaki, Koichi

    2017-03-01

    We developed a diode laser-based system for measuring the sheath electric fields in low-temperature plasmas. The Stark spectrum of the Balmer-α line of atomic hydrogen was measured by saturation spectroscopy with a fine spectral resolution. The spectrum observed experimentally was consistent with the theoretical Stark spectrum, and we succeeded in evaluating the electric field strength on the basis of the experimental Stark spectrum. A sensitive detection limit of 10 V/cm was achieved by the developed system.

  12. On-line continuous generation of zinc chelates in the vapor phase by reaction with sodium dithiocarbamates and determination by atomic fluorescence spectrometry

    Science.gov (United States)

    Duan, Xuchuan; Sun, Rui; Fang, Jinliang

    2017-02-01

    The present study shows for the first time that a volatile zinc chelate species can be generated by the on-line continuous merging of an acidified sample solution with an aqueous sodium diethyldithiocarbamate solution followed by rapid separation using a frit-based bubble gas-liquid separator at room temperature. The operating conditions for the generation of the vaporous zinc chelate were preliminarily investigated by non-dispersive atomic fluorescence spectrometry. The possible mechanism of zinc vapor generation is discussed. The study shows that the volatile species is an intermediate species with very similar properties to diethyldithiocarbamic acid and a very short half-life in the acidic solution. Moreover, this species can only be generated by on-line mixing and rapid separation. The efficiency of generation was 33-85% depending on acidity. Under optimal conditions, the flow rates of the sample and Na-DDTC solution were 1.3 ml min- 1, the carrier argon flow rate was 225 ml min- 1, the acid concentration of the sample solution and the concentration of Na-DDTC were 0.05 M and 0.4% (m/v), respectively, the detection limit of zinc was 0.33 (3σ) ng ml- 1, and the relative standard deviation (RSD) was 1.3%. The accuracy of the method was verified by the determination of zinc in the plant reference materials GBW10015 (spinach) and GBW10045 (rice). The results were in good agreement with the certified reference values.

  13. c2d Spitzer IRS spectra of embedded low-mass young stars: gas-phase emission lines

    Science.gov (United States)

    Lahuis, F.; van Dishoeck, E. F.; Jørgensen, J. K.; Blake, G. A.; Evans, N. J.

    2010-09-01

    Context. A survey of mid-infrared gas-phase emission lines of H2, H2O and various atoms toward a sample of 43 embedded low-mass young stars in nearby star-forming regions is presented. The sources are selected from the Spitzer “Cores to Disks” (c2d) legacy program. Aims: The environment of embedded protostars is complex both in its physical structure (envelopes, outflows, jets, protostellar disks) and the physical processes (accretion, irradiation by UV and/or X-rays, excitation through slow and fast shocks) which take place. The mid-IR spectral range hosts a suite of diagnostic lines which can distinguish them. A key point is to spatially resolve the emission in the Spitzer-IRS spectra to separate extended PDR and shock emission from compact source emission associated with the circumstellar disk and jets. Methods: An optimal extraction method is used to separate both spatially unresolved (compact, up to a few hundred AU) and spatially resolved (extended, thousand AU or more) emission from the IRS spectra. The results are compared with the c2d disk sample and literature PDR and shock models to address the physical nature of the sources. Results: Both compact and extended emission features are observed. Warm (T_ex few hundred K) H2, observed through the pure rotational H2 S(0), S(1) and S(2) lines, and [S i] 25 μm emission is observed primarily in the extended component. [S i] is observed uniquely toward truly embedded sources and not toward disks. On the other hand hot (T_ex ⪆ 700 K) H2, observed primarily through the S(4) line, and [Ne ii] emission is seen mostly in the spatially unresolved component. [Fe ii] and [Si ii] lines are observed in both spatial components. Hot H2O emission is found in the spatially unresolved component of some sources. Conclusions: The observed emission on ≥1000 AU scales is characteristic of PDR emission and likely originates in the outflow cavities in the remnant envelope created by the stellar wind and jets from the embedded

  14. Commercial potential of natural gas storage in lined rock caverns (LRC)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-11-01

    The geologic conditions in many regions of the United States will not permit the development of economical high-deliverability gas storage in salt caverns. These regions include the entire Eastern Seaboard; several northern states, notably Minnesota and Wisconsin; many of the Rocky Mountain States; and most of the Pacific Northwest. In late 1997, the United States Department of Energy (USDOE) Federal Energy Technology Center engaged Sofregaz US to investigate the commercialization potential of natural gas storage in Lined Rock Caverns (LRC). Sofregaz US teamed with Gaz de France and Sydkraft, who had formed a consortium, called LRC, to perform the study for the USDOE. Underground storage of natural gas is generally achieved in depleted oil and gas fields, aquifers, and solution-mined salt caverns. These storage technologies require specific geologic conditions. Unlined rock caverns have been used for decades to store hydrocarbons - mostly liquids such as crude oil, butane, and propane. The maximum operating pressure in unlined rock caverns is limited, since the host rock is never entirely impervious. The LRC technology allows a significant increase in the maximum operating pressure over the unlined storage cavern concept, since the gas in storage is completely contained with an impervious liner. The LRC technology has been under development in Sweden by Sydkraft since 1987. The development process has included extensive technical studies, laboratory testing, field tests, and most recently includes a storage facility being constructed in southern Sweden (Skallen). The LRC development effort has shown that the concept is technically and economically viable. The Skallen storage facility will have a rock cover of 115 meters (375 feet), a storage volume of 40,000 cubic meters (250,000 petroleum barrels), and a maximum operating pressure of 20 MPa (2,900 psi). There is a potential for commercialization of the LRC technology in the United States. Two regions were studied

  15. The ATLAS 3D project - XVI. Physical parameters and spectral line energy distributions of the molecular gas in gas-rich early-type galaxies

    CERN Document Server

    Bayet, Estelle; Davis, Timothy A; Young, Lisa M; Crocker, Alison F; Alatalo, Katherine; Blitz, Leo; Bois, Maxime; Bournaud, Frédéric; Cappellari, Michele; Davies, Roger L; de Zeeuw, P T; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Krajnović, Davor; Kuntschner, Harald; McDermid, Richard M; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Scott, Nicholas; Serra, Paolo; Weijmans, Anne-Marie

    2012-01-01

    [Abridged] We present a detailed study of the physical properties of the molecular gas in a sample of 18 molecular gas-rich early-type galaxies (ETGs) from the ATLAS$ 3D sample. Our goal is to better understand the star formation processes occurring in those galaxies, starting here with the dense star-forming gas. We use existing integrated $^{12}$CO(1-0, 2-1), $^{13}$CO(1-0, 2-1), HCN(1-0) and HCO$^{+}$(1-0) observations and present new $^{12}$CO(3-2) single-dish data. From these, we derive for the first time the average kinetic temperature, H$_{2}$ volume density and column density of the emitting gas, this using a non-LTE theoretical model. Since the CO lines trace different physical conditions than of those the HCN and HCO$^{+}$ lines, the two sets of lines are treated separately. We also compare for the first time the predicted CO spectral line energy distributions (SLEDs) and gas properties of our molecular gas-rich ETGs with those of a sample of nearby well-studied disc galaxies. The gas excitation con...

  16. On-Line, Real-Time Diagnostics of a Single Fluid Atomization System

    Science.gov (United States)

    DelshadKhatibi, P.; Ilbagi, A.; Henein, H.

    2012-01-01

    A drop tube-Impulse Atomization technique was used to produce copper droplets. In this method, energy is transferred to a liquid by plunger movement resulting in spherical droplets emanating from orifices. A mathematical model of the evolution of droplet velocity and temperature at various heights for different sized droplets was developed. A two-color pyrometer, DPV-2000, and a shadowgraph were used to measure droplets radiant energy, diameter and velocity. The temperature values from the model were used to assess the two color pyrometer assumption over the temperature range of measurement. The DVP 2000 measurements were found to be dependent of droplet size wavelength and position of droplets below the atomizing nozzle. By calibrating the instrument for effective emissivity over the range of measurements, the thermal history of droplets may be recorded using a single color pyrometer approach.

  17. A microstructural investigation of gas atomized Raney type Al-27.5 at.% Ni catalyst precursor alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mullis, A.M., E-mail: a.m.mullis@leeds.ac.uk [Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom); Bigg, T.D., E-mail: t.bigg@leeds.ac.uk [Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom); Adkins, N.J., E-mail: n.j.e.adkins@bham.ac.uk [IRC in Materials Processing, University of Birmingham, Edgbaston, Birmingham B15-2TT (United Kingdom)

    2015-11-05

    Quantitative image analysis has been used to investigate the phase composition of gas atomized powders of a Raney type Ni catalyst precursor alloys of composition Al-27.5 at.% Ni in the powder size range 150–212 μm. We find that there are considerable variations in phase composition both between powders from the same batch and as a function distance from the particle surface within individual particles. Such variations may have significant implications for the future production and uptake of such catalysts, including the necessity for post-production crushing of gas atomized powders. Models are proposed to account for both variations. - Highlights: • The phase composition of powder Raney-Ni catalysts has been investigated. • Image analysis is used to quantify differences between and within particles. • Phase composition can vary by up to 10% between the particle surface and centre. • Differences of up to 10% in the mean composition are also found between particles.

  18. Study of AB{sub 2} alloy electrodes for Ni/MH battery prepared by centrifugal casting and gas atomization

    Energy Technology Data Exchange (ETDEWEB)

    Young, K., E-mail: kwoyoung@yahoo.co [Energy Conversion Devices Inc./Ovonic Battery Company, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Koch, J.; Ouchi, T. [Energy Conversion Devices Inc./Ovonic Battery Company, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Banik, A. [Special Metal Corporation, 100 Industry Lane, Princeton, KY 42445 (United States); Fetcenko, M.A. [Energy Conversion Devices Inc./Ovonic Battery Company, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States)

    2010-04-30

    Centrifugal casting and gas atomization processes were applied on multiple phase AB{sub 2} alloys and compared to the conventional melt-and-cast. Four different compositions were chosen for this study. The roles of Zr, Mn, Cr, and Ni in various battery aspects are identified. Cooling speed was found to be crucial for the C14 and C15 phase abundances. As the cooling speed increased from 10{sup 2} to 10{sup 4} degrees per second, a higher percentage of C15 was found. The centrifugal casting process provided better cycle life and low temperature performance with the only trade-off being slower activation. The gas atomization process can achieve lower production cost due to the elimination of a grinding procedure and extended cycle life, but suffers from higher bulk oxygen content and thicker surface oxide, and thus inferior in all battery performance characteristics other than cycle life and charge retention.

  19. Active narrowband filtering, line narrowing and gain using ladder electromagnetically induced transparency in an optically thick atomic vapour

    CERN Document Server

    Keaveney, James; Sarkisyan, David; Papoyan, Aram; Adams, Charles S

    2013-01-01

    Electromagnetically induced transparency (EIT) resonances using the $5\\rm{S}_{1/2}\\rightarrow5\\rm{P}_{3/2}\\rightarrow5\\rm{D}_{5/2}$ ladder-system in optically thick Rb atomic vapour are studied. We observe a strong line narrowing effect and gain at the $5\\rm{S}_{1/2}\\rightarrow5\\rm{P}_{3/2}$ transition wavelength due to an energy-pooling assisted frequency conversion with characteristics similar to four-wave mixing. As a result it is possible to observe tunable and switchable transparency resonances with amplitude close to $100\\%$ and a linewidth of 15 MHz. In addition, the large line narrowing effect allows resolution of $^{85}$Rb $5\\rm{D}_{5/2}$ hyperfine structure even in the presence of strong power broadening.

  20. A Statistical Study of H I Gas in Nearby Narrow-Line AGN-Hosting Galaxies

    CERN Document Server

    Zhu, Yi-Nan

    2015-01-01

    As a quenching mechanism, AGN feedback could suppress on-going star formation in their host galaxies. On the basis of a sample of galaxies selected from ALFALFA HI survey, the dependence of their HI mass M[HI], stellar mass M[*] & HI-to-stellar mass ratio M[HI]/M[*] on various tracers of AGN activity are presented and analyzed in this paper. Almost all the AGN-hostings in this sample are gas-rich galaxies, and there is no any evidence to be shown to indicate that the AGN activity could increase/decrease either M[HI] or M[HI]/M[*]. The cold neutral gas can not be fixed positions accurately just based on available HI data due to the large beam size of ALFALFA survey. In addition, even though AGN-hostings are more easily detected by HI survey compared with absorption line galaxies, these two types of galaxies show similar star formation history. If an AGN-hosting would ultimately evolve into an old red galaxy with few cold gas, then when and how the gas has been exhausted have to be solved by future hypothes...

  1. A statistical study of H i gas in nearby narrow-line AGN-hosting galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yi-Nan; Wu, Hong, E-mail: zyn@bao.ac.cn, E-mail: hwu@bao.ac.cn [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2015-01-01

    As a quenching mechanism, active galactic nucleus (AGN) feedback could suppress on going star formation in host galaxies. On the basis of a sample of galaxies selected from the Arecibo Legacy Fast ALFA (ALFALFA) H i survey, the dependence of the H i mass (M{sub H} {sub i}), stellar mass (M{sub *}), and H i-to-stellar mass ratio (M{sub H} {sub i}/M{sub *}) on various tracers of AGN activity are presented and analyzed in this paper. Almost all the AGN hostings in this sample are gas-rich galaxies, and there is not any evidence to indicate that the AGN activity could increase or decrease either M{sub H} {sub i} or M{sub H} {sub i}/M{sub *}. The position of the cold neutral gas cannot be fixed accurately based only on available H i data, due to the large beam size of ALFALFA survey. In addition, even though AGN hostings are more easily detected by an H i survey compared with absorption line galaxies, these two types of galaxies show similar star formation history. If an AGN hosting would ultimately evolve into an old red galaxy with low cold gas, then when and how the gas has been exhausted must be solved by future hypotheses and observations.

  2. Foreign gas broadening and shift of the strongly ``forbidden'' lead line at 1278.9nm

    Science.gov (United States)

    Horvatic, Vlasta; Veza, Damir; Movre, Mladen; Niemax, Kay; Vadla, Cedomil

    2008-06-01

    The collisional broadening and shift rate coefficients of the "forbidden" 6p 2 3P 0 → 6p 2 3P 1 transition in lead were determined by diode laser absorption measurements performed simultaneously in two resistively heated hot-pipes. One hot-pipe contained Pb vapor and noble gas (Ar or He) at low pressure, while the other was filled with Pb and noble gas at variable pressure. The measurements were performed at temperatures of 1220 K and 1290 K, i.e., lead number densities of 4.8 × 10 15 cm - 3 and 1.2 × 10 16 cm - 3 . The broadening rates were obtained by fitting the experimental collisionally broadened absorption line shapes to theoretical Voigt profiles. The shift rates were determined by measuring the difference between the peak absorption positions in the spectra measured simultaneously in the heat pipe filled with noble gas at reference pressure and the one with noble gas at variable pressure. The following data for the broadening and shift rate coefficients due to collisions with Ar and He were obtained: γBAr = (3.4 ± 0.1) × 10 - 10 cm 3 s - 1 , γBHe = (3.8 ± 0.1) × 10 - 10 cm 3 s - 1 , γSAr = (- 7.3 ± 0.8) × 10 - 11 cm 3 s - 1 , γSHe = (- 6.5 ± 0.7) × 10 - 11 cm 3 s - 1 .

  3. Atomic structure calculations and identification of EUV and SXR spectral lines in Sr XXX

    Science.gov (United States)

    Goyal, Arun; Khatri, Indu; Aggarwal, Sunny; Singh, A. K.; Mohan, Man

    2015-08-01

    We report an extensive theoretical study of atomic data for Sr XXX in a wide range with L-shell electron excitations to the M-shell. We have calculated energy levels, wave-function compositions and lifetimes for lowest 113 fine structure levels and wavelengths of an extreme Ultraviolet (EUV) and soft X-ray (SXR) transitions. We have employed multi-configuration Dirac Fock method (MCDF) approach within the framework of Dirac-Coulomb Hamiltonian including quantum electrodynamics (QED) and Breit corrections. We have also presented the radiative data for electric and magnetic dipole (E1, M1) and quadrupole (E2, M2) transitions from the ground state. We have made comparisons with available energy levels compiled by NIST and achieve good agreement. But due to inadequate data in the literature, analogous relativistic distorted wave calculations have also been performed using flexible atomic code (FAC) to assess the reliability and accuracy of our results. Additionally, we have provided new atomic data for Sr XXX which is not published elsewhere in the literature and we believe that our results may be beneficial in fusion plasma research and astrophysical investigations and applications.

  4. Semi-flexible gas-insulated transmission line using sandwiched discs for intermittent flexing joints

    Energy Technology Data Exchange (ETDEWEB)

    Kommineni, Prasad R. (Westboro, MA)

    1983-02-15

    A gas-insulated transmission line includes an outer sheath, an inner conductor, an insulating gas electrically insulating the inner conductor from the outer sheath, and insulating supports insulatably supporting the inner conductor within the outer sheath. The inner conductor is provided with flexibility by the use of main conductor sections which are joined together through a conductor hub section and flexible flexing elements. Stress shields are provided to control the electric field at the locations of the conductor hub sections where the insulating supports are contacting the inner conductor. The flexing elements are formed by sandwiching together, by fusing, a pair of thin hollow discs which are fixedly secured to both the main conductor sections and the conductor hub section.

  5. Semi-flexible gas-insulated transmission line using sandwiched discs for intermittent flexing joints

    Energy Technology Data Exchange (ETDEWEB)

    Kommineni, P.R.

    1983-02-15

    A gas-insulated transmission line includes an outer sheath, an inner conductor, an insulating gas electrically insulating the inner conductor from the outer sheath, and insulating supports insulatably supporting the inner conductor within the outer sheath. The inner conductor is provided with flexibility by the use of main conductor sections which are joined together through a conductor hub section and flexible flexing elements. Stress shields are provided to control the electric field at the locations of the conductor hub sections where the insulating supports are contacting the inner conductor. The flexing elements are formed by sandwiching together, by fusing, a pair of thin hollow discs which are fixedly secured to both the main conductor sections and the conductor hub section. 4 figs.

  6. Advancements in Ti Alloy Powder Production by Close-Coupled Gas Atomization

    Energy Technology Data Exchange (ETDEWEB)

    Heidloff, Andy; Rieken, Joel; Anderson, Iver; Byrd, David

    2011-04-01

    As the technology for titanium metal injection molding (Ti-MIM) becomes more readily available, efficient Ti alloy fine powder production methods are required. An update on a novel close-coupled gas atomization system has been given. Unique features of the melting apparatus are shown to have measurable effects on the efficiency and ability to fully melt within the induction skull melting system (ISM). The means to initiate the melt flow were also found to be dependent on melt apparatus. Starting oxygen contents of atomization feedstock are suggested based on oxygen pick up during the atomization and MIM processes and compared to a new ASTM specification. Forming of titanium by metal injection molding (Ti-MIM) has been extensively studied with regards to binders, particle shape, and size distribution and suitable de-binding methods have been discovered. As a result, the visibility of Ti-MIM has steadily increased as reviews of technology, acceptability, and availability have been released. In addition, new ASTM specification ASTM F2885-11 for Ti-MIM for biomedical implants was released in early 2011. As the general acceptance of Ti-MIM as a viable fabrication route increases, demand for economical production of high quality Ti alloy powder for the preparation of Ti-MIM feedstock correspondingly increases. The production of spherical powders from the liquid state has required extensive pre-processing into different shapes thereby increasing costs. This has prompted examination of Ti-MIM with non-spherical particle shape. These particles are produced by the hydride/de-hydride process and are equi-axed but fragmented and angular which is less than ideal. Current prices for MIM quality titanium powder range from $40-$220/kg. While it is ideal for the MIM process to utilize spherical powders within the size range of 0.5-20 {mu}m, titanium's high affinity for oxygen to date has prohibited the use of this powder size range. In order to meet oxygen requirements the top

  7. On the role of atomic metastability in the production of Balmer line radiation from ‘cold’ atomic hydrogen, deuterium and hydrogenic ion impurities in fusion edge plasmas

    Science.gov (United States)

    Hey, J. D.

    2012-03-01

    Published arguments, which assign an important role to atomic metastability in the production of ‘narrow’ Zeeman component radiation from the boundary region of fusion plasmas, are examined critically in relation to l-redistribution by proton and electron collisions, and mixing of unperturbed atomic states by the ion microfield and microfield gradient. It is concluded that these important processes indeed severely constrain the contribution from ‘metastable’ states to the generation of the hydrogen Balmer spectra, for electron concentrations above 1012 cm-3, as pointed out before by the present author (Hey et al 1999 J. Phys. B: At. Mol. Opt. Phys. 32 3555). The analysis of collision-induced l-redistribution represents an extension of that used previously (Hey et al 1996 Contrib. Plasma Phys. 36 583), applicable up to higher electron densities. For comparison purposes, we also consider the question of metastability of ionized helium in a low-temperature plasma, and that of some common hydrogenic impurities (C5+ and Ne9+) in a hydrogen (deuterium) fusion plasma. While for low nuclear charge Z the metastability of 2s1/2 levels is quenched by the plasma environment, it is much reduced in high-Z ions owing to the rapid increase with Z of the two-photon electric dipole (2E1) and magnetic dipole (M1) spontaneous transition rates to the ground state, whereas the role of the plasma in these cases is less important. The main new principle elaborated in this work is the sensitivity of atomic line strengths, and hence collision strengths, to perturbation by the plasma environment for transitions between fine-structure sublevels of the same principal quantum number. As the plasma microfield strength grows, ‘allowed’ transitions diminish in strength, while ‘forbidden’ transitions grow. However, owing to violation of the parity selection rule, there is an overall loss of collision strength available to transitions, resulting from the appearance of significant

  8. Precise atomic-scale investigations of material sputtering process by light gas ions in pre-threshold energy region

    CERN Document Server

    Suvorov, A L

    2002-01-01

    Foundation and prospects of the new original technique of the sputtering yield determination of electro-conducting materials and sub-atomic layers on their surface by light gas ions the pre-threshold energy region (from 10 to 500 eV) are considered. The technique allows to identify individual surface vacancies, i.e., to count individual sputtered atoms directly. A short review of the original results obtained by using the developed techniques is given. Data are presented and analyzed concerning energy thresholds of the sputtering onset and energy dependences of sputtering yield in the threshold energy region for beryllium, tungsten, tungsten oxide, alternating tungsten-carbon layers, three carbon materials as well as for sub-atomic carbon layers on surface of certain metals at their bombardment by hydrogen, deuterium and/or helium ions

  9. Reaction of Np atom with H₂O in the gas phase: reaction mechanisms and ab initio molecular dynamics study.

    Science.gov (United States)

    Li, Peng; Niu, Wenxia; Gao, Tao; Wang, Hongyan

    2014-10-01

    The gas-phase reaction of an Np atom with H2O was investigated using density functional theory and ab initio molecular dynamics. The reaction mechanisms and the corresponding potential energy profiles for different possible spin states were analyzed. Three reaction channels were found in the mechanism study: the isomerization channel, the H2 elimination channel, and the H atom elimination channel. The latter two were observed in the dynamics simulation. It was found that the branching ratio of the title reaction depends on the initial kinetic energy along the transition vector. Product energy distributions for the reaction were evaluated by performing direct classical trajectory calculations on the lowest sextet potential energy surface. The results indicate that most of the available energy appears as the translational energy of the products. The overall results indicate that the H2 elimination channel with low kinetic energy is thermodynamically favored but competes with the H atom elimination channel with higher kinetic energy.

  10. Narrow-line region gas kinematics of 24 264 optically selected AGN: the radio connection

    Science.gov (United States)

    Mullaney, J. R.; Alexander, D. M.; Fine, S.; Goulding, A. D.; Harrison, C. M.; Hickox, R. C.

    2013-07-01

    Using a sample of 24 264 optically selected active galactic nuclei (AGNs) from the SDSS DR7 data base, we characterize how the profile of the [O III] λ5007 emission line relates to bolometric luminosity (LAGN), Eddington ratio, radio loudness, radio luminosity (L1.4 GHz) and optical class (i.e. broad/narrow-line Seyfert 1, type 2) to determine what drives the kinematics of this kpc-scale line emitting gas. First, we use spectral stacking to characterize how the average [O III] λ5007 profile changes as a function of these five variables. After accounting for the known correlation between LAGN and L1.4 GHz, we report that L1.4 GHz has the strongest influence on the [O III] λ5007 profile, with AGNs of moderate radio luminosity (L1.4 GHz = 1023-1025 W Hz-1) having the broadest [O III] λ5007 profiles. Conversely, we find only a modest change in the [O III] λ5007 profile with increasing radio loudness and find no significant difference between the [O III] λ5007 profiles of broad- and narrow-line Seyfert 1s. When binned according to Eddington ratio, only the AGNs in our highest bin (i.e. >0.3) show any signs of having broadened [O III] λ5007 profiles, although the small numbers of such extreme AGNs in our sample mean we cannot rule out that other processes (e.g. radio jets) are responsible for this broadening. The [O III] λ5007 profiles of type 1 and type 2 AGNs show the same trends in terms of line width, but type 1 AGNs display a much stronger `blue wing', which we interpret as evidence of outflowing ionized gas. We perform multicomponent fitting to the Hβ, [O III] λλ4959, 5007, [N II] λλ6548, 6584 and Hα lines for all the AGNs in our sample to calculate the proportions of AGNs with broad [O III] λ5007 profiles. The individual fits confirm the results from our stacked spectra; AGNs with L1.4 GHz > 1023 W Hz-1 are roughly five times more likely to have extremely broad [O III] λ5007 lines (full width at half-maximum, FWHMAvg > 1000 km s-1) compared to

  11. Effects of aluminum additions to gas atomized reaction synthesis produced oxide dispersion strengthened alloys

    Science.gov (United States)

    Spicher, Alexander Lee

    The production of an aluminum containing ferritic oxide dispersion strengthened (ODS) alloy was investigated. The production method used in this study was gas atomization reaction synthesis (GARS). GARS was chosen over the previously commercial method of mechanical alloying (MA) process due to complications from this process. The alloy compositions was determined from three main components; corrosion resistance, dispersoid formation, and additional elements. A combination of Cr and Al were necessary in order to create a protective oxide in the steam atmosphere that the boiler tubing in the next generation of coal-fired power plants would be exposed to. Hf and Y were chosen as dispersoid forming elements due to their increased thermal stability and potential to avoid decreased strength caused by additions of Al to traditional ODS materials. W was used as an additive due to benefits as a strengthener as well as its benefits for creep rupture time. The final composition chosen for the alloy was Fe-16Cr-12Al-0.9W-0.25Hf-0.2Y at%. The aforementioned alloy, GA-1-198, was created through gas atomization with atomization gas of Ar-300ppm O2. The actual composition created was found to be Fe-15Cr-12.3Al-0.9W-0.24Hf-0.19Y at%. An additional alloy that was nominally the same without the inclusion of aluminum was created as a comparison for the effects on mechanical and corrosion properties. The actual composition of the comparison alloy, GA-1-204, was Fe-16Cr-0Al-0.9W-0.25Hf-0.24Y at%. An investigation on the processing parameters for these alloys was conducted on the GA-1-198 alloy. In order to predict the necessary amount of time for heat treatment, a diffusion study was used to find the diffusion rate of oxygen in cast alloys with similar composition. The diffusion rate was found to be similar to that of other GARS compositions that have been created without the inclusion of aluminum. The effect of heat treatment time was investigated with temperatures of 950°C, 1000

  12. c2d Spitzer IRS spectra of embedded low-mass young stars: gas-phase emission lines

    CERN Document Server

    Lahuis, Fred; Jørgensen, Jes K; Blake, Geoffrey A; Evans, Neal J

    2010-01-01

    A survey of mid-IR gas-phase emission lines of H2, H2O and various atoms toward a sample of 43 embedded low-mass young stars in nearby star-forming regions is presented. The sources are selected from the Spitzer "Cores to Disks" (c2d) legacy program. The environment of embedded protostars is complex both in its physical structure (envelopes, outflows, jets, protostellar disks) and the physical processes (accretion, irradiation by UV and/or X-rays, excitation through slow and fast shocks) which take place. A key point is to spatially resolve the emission in the Spitzer-IRS spectra. An optimal extraction method is used to separate both spatially unresolved (compact, up to a few 100 AU) and spatially resolved (extended, 1000 AU or more) emission from the IRS spectra. The results are compared with the c2d disk sample and literature PDR and shock models to address the physical nature of the sources. Both compact and extended emission features are observed. Warm (Tex few 100 K) H2, observed through the pure rotatio...

  13. A system for accurate on-line measurement of total gas consumption or production rates in microbioreactors

    NARCIS (Netherlands)

    Leeuwen, van Michiel; Heijnen, Joseph J.; Gardeniers, Han; Oudshoorn, Arthur; Noorman, Henk; Visser, Jan; Wielen, van der Luuk A.M.; Gulik, van Walter M.

    2009-01-01

    A system has been developed, based on pressure controlled gas pumping, for accurate measurement of total gas consumption or production rates in the nmol/min range, applicable for on-line monitoring of bioconversions in microbioreactors. The system was validated by carrying out a bioconversion with k

  14. A new technique to measure the neutralizer cell gas line density applied to a DIII-D neutral beamline

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, D.N.; Hong, R.M.; Riggs, S.P.

    1995-10-01

    The DIII-D tokamak employs eight ion sources for plasma heating. In order to obtain the maximum neutralization of energetic ions (providing maximum neutral beam power) and reduce the heat load on beamline internal components caused by residual energetic ions, sufficient neutral gas must be injected into the beamline neutralizer cell. The neutral gas flow rate must be optimized, however, since excessive gas will increase power losses due to neutral beam scattering and reionization. It is important, therefore, to be able to determine the neutralizer cell gas line density. A new technique which uses the ion source suppressor grid current to obtain the neutralizer cell gas line density has been developed. The technique uses the fact that slow ions produced by beam-gas interactions in the neutralizer cell during beam extraction are attracted to the negative potential applied to the suppressor grid, inducing current flow in the grid. By removing the dependence on beam energy and beam current a normalized suppressor grid current function can be formed which is dependent only on the gas line density. With this technique it is possible to infer the gas line density on a shot by shot basis.

  15. The solar photospheric abundance of carbon.Analysis of atomic carbon lines with the CO5BOLD solar model

    CERN Document Server

    Caffau, E; Bonifacio, P; Faraggiana, R; Steffen, M; Freytag, B; Kamp, I; Ayres, T R

    2010-01-01

    The use of hydrodynamical simulations, the selection of atomic data, and the computation of deviations from local thermodynamical equilibrium for the analysis of the solar spectra have implied a downward revision of the solar metallicity. We are in the process of using the latest simulations computed with the CO5BOLD code to reassess the solar chemical composition. We determine the solar photospheric carbon abundance by using a radiation-hydrodynamical CO5BOLD model, and compute the departures from local thermodynamical equilibrium by using the Kiel code. We measure equivalent widths of atomic CI lines on high resolution, high signal-to-noise ratio solar atlases. Deviations from local thermodynamic equilibrium are computed in 1D with the Kiel code. Our recommended value for the solar carbon abundance, relies on 98 independent measurements of observed lines and is A(C)=8.50+-0.06, the quoted error is the sum of statistical and systematic error. Combined with our recent results for the solar oxygen and nitrogen...

  16. Imaging galactic diffuse gas: bright, turbulent CO surrounding the line of sight to NRAO150

    Science.gov (United States)

    Pety, J.; Lucas, R.; Liszt, H. S.

    2008-10-01

    Aims: To understand the environment and extended structure of the host galactic gas whose molecular absorption line chemistry, we previously observed along the microscopic line of sight to the blazar/radiocontinuum source NRAO150 (aka B0355+508). Methods: We used the IRAM 30 m Telescope and Plateau de Bure Interferometer to make two series of images of the host gas: i) 22.5'' resolution single-dish maps of 12CO J = 1-0 and 2-1 emission over a 220'' by 220'' field; ii) a hybrid (interferometer+singledish) aperture synthesis mosaic of 12CO J = 1-0 emission at 5.8'' resolution over a 90''-diameter region. Results: At 22.5'' resolution, the CO J = 1-0 emission toward NRAO150 is 30-100% brighter at some velocities than seen previously with 1' resolution, and there are some modest systematic velocity gradients over the 220'' field. Of the five CO components seen in the absorption spectra, the weakest ones are absent in emission toward NRAO150 but appear more strongly at the edges of the region mapped in emission. The overall spatial variations in the strongly emitting gas have Poisson statistics with rms fluctuations about equal to the mean emission level in the line wings and much of the line cores. The J = 2-1/J = 1-0 line ratios calculated pixel-by-pixel cluster around 0.7. At 6'' resolution, disparity between the absorption and emission profiles of the stronger components has been largely ameliorated. The 12CO J = 1-0 emission exhibits i) remarkably bright peaks, {T}_mb = 12-13 K, even as 4'' from NRAO150; ii) smaller relative levels of spatial fluctuation in the line cores, but a very broad range of possible intensities at every velocity; and iii) striking kinematics whereby the monotonic velocity shifts and supersonically broadened lines in 22.5'' spectra are decomposed into much stronger velocity gradients and abrupt velocity reversals of intense but narrow, probably subsonic, line cores. Conclusions: CO components that are observed in absorption at a moderate

  17. Speciation analysis of arsenic by selective hydride generation-cryotrapping-atomic fluorescence spectrometry with flame-in-gas-shield atomizer: achieving extremely low detection limits with inexpensive instrumentation.

    Science.gov (United States)

    Musil, Stanislav; Matoušek, Tomáš; Currier, Jenna M; Stýblo, Miroslav; Dědina, Jiří

    2014-10-21

    This work describes the method of a selective hydride generation-cryotrapping (HG-CT) coupled to an extremely sensitive but simple in-house assembled and designed atomic fluorescence spectrometry (AFS) instrument for determination of toxicologically important As species. Here, an advanced flame-in-gas-shield atomizer (FIGS) was interfaced to HG-CT and its performance was compared to a standard miniature diffusion flame (MDF) atomizer. A significant improvement both in sensitivity and baseline noise was found that was reflected in improved (4 times) limits of detection (LODs). The yielded LODs with the FIGS atomizer were 0.44, 0.74, 0.15, 0.17 and 0.67 ng L(-1) for arsenite, total inorganic, mono-, dimethylated As and trimethylarsine oxide, respectively. Moreover, the sensitivities with FIGS and MDF were equal for all As species, allowing for the possibility of single species standardization with arsenate standard for accurate quantification of all other As species. The accuracy of HG-CT-AFS with FIGS was verified by speciation analysis in two samples of bottled drinking water and certified reference materials, NRC CASS-5 (nearshore seawater) and SLRS-5 (river water) that contain traces of methylated As species. As speciation was in agreement with results previously reported and sums of all quantified species corresponded with the certified total As. The feasibility of HG-CT-AFS with FIGS was also demonstrated by the speciation analysis in microsamples of exfoliated bladder epithelial cells isolated from human urine. The results for the sums of trivalent and pentavalent As species corresponded well with the reference results obtained by HG-CT-ICPMS (inductively coupled plasma mass spectrometry).

  18. HERschel Observations of Edge-on Spirals (HEROES). II: Tilted-ring modelling of the atomic gas disks

    CERN Document Server

    Allaert, F; Baes, M; De Geyter, G; Hughes, T M; Lewis, F; Bianchi, S; De Looze, I; Fritz, J; Holwerda, B W; Verstappen, J; Viaene, S

    2015-01-01

    Context. Edge-on galaxies can offer important insights in galaxy evolution as they are the only systems where the distribution of the different components can be studied both radially and vertically. The HEROES project was designed to investigate the interplay between the gas, dust, stars and dark matter (DM) in a sample of 7 massive edge-on spiral galaxies. Aims. In this second HEROES paper we present an analysis of the atomic gas content of 6 out of 7 galaxies in our sample. The remaining galaxy was recently analysed according to the same strategy. The primary aim of this work is to constrain the surface density distribution, the rotation curve and the geometry of the gas disks in a homogeneous way. In addition we identify peculiar features and signs of recent interactions. Methods. We construct detailed tilted-ring models of the atomic gas disks based on new GMRT 21-cm observations of NGC 973 and UGC 4277 and re-reduced archival HI data of NGC 5907, NGC 5529, IC 2531 and NGC 4217. Potential degeneracies be...

  19. Imaging galactic diffuse gas: Bright, turbulent CO surrounding the line of sight to NRAO150

    CERN Document Server

    Pety, Jérôme; Liszt, Harvey S

    2008-01-01

    To understand the environment and extended structure of the host galactic gas whose molecular absorption line chemistry, we previously observed along the microscopic line of sight to the blazar/radiocontinuum source NRAO150 (aka B0355+508), we used the IRAM 30m Telescope and Plateau de Bure Interferometer to make two series of images of the host gas: i) 22.5 arcsec resolution single-dish maps of 12CO J=1-0 and 2-1 emission over a 220 arcsec by 220 arcsec field; ii) a hybrid (interferometer+singledish) aperture synthesis mosaic of 12CO J=1-0 emission at 5.8 arcsec resolution over a 90 arcsec-diameter region. CO components that are observed in absorption at a moderate optical depth (0.5) and are undetected in emission at 1 arcmin resolution toward NRAO 150 remain undetected at 6 arcsec resolution. This implies that they are not a previously-hidden large-scale molecular component revealed in absorption, but they do highlight the robustness of the chemistry into regions where the density and column density are to...

  20. High star formation rates in turbulent atomic-dominated gas in the interacting galaxies IC 2163 and NGC 2207

    CERN Document Server

    Elmegreen, Bruce G; Bournaud, Frederic; Elmegreen, Debra Meloy; Struck, Curtis; Brinks, Elias; Juneau, Stephanie

    2016-01-01

    CO observations of the interacting galaxies IC 2163 and NGC 2207 are combined with HI, Halpha and 24 microns to study the star formation rate (SFR) surface density as a function of the gas surface density. More than half of the high SFR regions are HI dominated. When compared to other galaxies, these HI-dominated regions have excess SFRs relative to their molecular gas surface densities but normal SFRs relative to their total gas surface densities. The HI-dominated regions are mostly located in the outer part of NGC 2207, where the HI velocity dispersion is high, 40 - 50 km/s. We suggest that the star-forming clouds in these regions have envelopes at lower densities than normal, making them predominantly atomic, and cores at higher densities than normal because of the high turbulent Mach numbers. This is consistent with theoretical predictions of a flattening in the density probability distribution function for compressive, high Mach number turbulence.

  1. Investigation of an alternating current plasma as an element selective atomic emission detector for high-resolution capillary gas chromatography and as a source for atomic absorption and atomic emission spectrometry

    Science.gov (United States)

    Ombaba, Jackson M.

    This thesis deals with the construction and evaluation of an alternating current plasma (ACP) as an element-selective detector for high resolution capillary gas chromatography (GC) and as an excitation source for atomic absorption spectrometry (AAS) and atomic emission spectrometry (AES). The plasma, constrained in a quartz discharge tube at atmospheric pressure, is generated between two copper electrodes and utilizes helium as the plasma supporting gas. The alternating current plasma power source consists of a step-up transformer with a secondary output voltage of 14,000 V at a current of 23 mA. The device exhibits a stable signal because the plasma is self-seeding and reignites itself every half cycle. A tesla coil is not required to commence generation of the plasma if the ac voltage applied is greater than the breakdown voltage of the plasma-supporting gas. The chromatographic applications studied included the following: (1) the separation and selective detection of the organotin species, tributyltin chloride (TBT) and tetrabutyltin (TEBT), in environmental matrices including mussels (Mvutilus edullus) and sediment from Boston Harbor, industrial waste water and industrial sludge, and (2) the detection of methylcyclopentadienyl manganesetricarbonyl (MMT) and similar compounds used as gasoline additives. An ultrasonic nebulizer (common room humidifier) was utilized as a sample introduction device for aqueous solutions when the ACP was employed as an atomization source for atomic absorption spectrometry and as an excitation source for atomic emission spectrometry. Plasma diagnostic parameters studied include spatial electron number density across the discharge tube, electronic, excitation and ionization temperatures. Interference studies both in absorption and emission modes were also considered. Figures of merits of selected elements both in absorption and emission modes are reported. The evaluation of a computer-aided optimization program, Drylab GC, using

  2. Chapter 13 Theoretical and Experimental Studies of the Gas-Phase Cl-Atom Initiated Reactions of Benzene and Toluene

    Science.gov (United States)

    Ryzhkov, A.; Ariya, P. A.; Raofie, F.; Niki, H.; Harris, G. W.

    The reactions of benzene (Bz) and toluene (PhMe) with chlorine atoms in the gas phase have been studied using both theoretical and experimental techniques. Energy and geometry of reaction complexes and transition states were calculated in the Cl-atom initiated reaction of benzene and toluene using modern hybrid functional PBE0 method with the aug-pc1 basis set with an additional CCSD(T)/aug-CC-pVDZ energy single point calculation. Three stationary structures have been found for the Bz...Cl complex: hexahapto-complex, [pi]-complex and [sigma]-complex. The first one is a transition state between two opposite [pi]-complexes. PhMe...Cl has additional structures due to ipso-, ortho-, meta- and para-isomerization. The stability of all calculated complexes was determined and compared. Two reaction pathways for benzene and toluene with a Cl atom were evaluated: (a) the hydrogen abstraction of benzene and toluene by Cl atom, which is seemingly barrierless and endothermic, and (b) the hydrogen substitution reaction that in contrast has a relatively high energy of activation. Rate coefficients for these same reactions were measured using ethane, n-butane, and chloro-, dichloro- and trichloromethane, as reference compounds, with gas chromatography equipped with mass detection spectrometry and flame ionization detection (GC-MSD and GC-FID). The reaction rates were estimated as (5.57±0.15)×10-11 and for benzene and toluene, respectively. Chlorinated products of the reactions were analyzed by GS-MS. Chlorobenzene was the only identified product between a reaction of benzene and the Cl atom. The major products of the PhMe + Cl reaction were chloromethylbenzene with ortho- and para-chlorotoluenes.

  3. Scattering of NH{sub 3} and ND{sub 3} with rare gas atoms at low collision energy

    Energy Technology Data Exchange (ETDEWEB)

    Loreau, J., E-mail: jloreau@ulb.ac.be [Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles (ULB) CP 160/09, 50 av. F.D. Roosevelt, 1050 Brussels (Belgium); Avoird, A. van der, E-mail: A.vanderAvoird@theochem.ru.nl [Theoretical Chemistry, Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands)

    2015-11-14

    We present a theoretical study of elastic and rotationally inelastic collisions of NH{sub 3} and ND{sub 3} with rare gas atoms (He, Ne, Ar, Kr, Xe) at low energy. Quantum close-coupling calculations have been performed for energies between 0.001 and 300 cm{sup −1}. We focus on collisions in which NH{sub 3} is initially in the upper state of the inversion doublet with j = 1, k = 1, which is the most relevant in an experimental context as it can be trapped electrostatically and Stark-decelerated. We discuss the presence of resonances in the elastic and inelastic cross sections, as well as the trends in the inelastic cross sections along the rare gas series and the differences between NH{sub 3} and ND{sub 3} as a colliding partner. We also demonstrate the importance of explicitly taking into account the umbrella (inversion) motion of NH{sub 3} in order to obtain accurate scattering cross sections at low collision energy. Finally, we investigate the possibility of sympathetic cooling of ammonia using cold or ultracold rare gas atoms. We show that some systems exhibit a large ratio of elastic to inelastic cross sections in the cold regime, which is promising for sympathetic cooling experiments. The close-coupling calculations are based on previously reported ab initio potential energy surfaces for NH{sub 3}–He and NH{sub 3}–Ar, as well as on new, four-dimensional, potential energy surfaces for the interaction of ammonia with Ne, Kr, and Xe, which were computed using the coupled-cluster method and large basis sets. We compare the properties of the potential energy surfaces corresponding to the interaction of ammonia with the various rare gas atoms.

  4. Multiple-Line Study of NGC 1068: Hot Molecular Gas Caused by Jet-Gas Interaction in the Central 100pc?

    Science.gov (United States)

    Krips, Melanie

    2012-07-01

    A multiple molecular line and line transition study is presented for the circumnuclear disk (CND) of the proto-typical Seyfert galaxy NGC 1068. A detailed analysis of the kinematics and excitation conditions of the molecular gas, as traced by 12CO, 13CO, HCN and HCO+, suggests that part of the molecular gas in the CND is shocked, expanding and heated to high kinetic temperatures most likely as a consequence of an interaction between the radio jet and the CND. We further find support for an X-ray altered chemistry of the molecular gas in the CND based on the significantly elevated abundance of HCN when compared to star-forming, starbursting or quiescent gas regions.

  5. Atlas of Atomic Spectral Lines of Neptunium Emitted by Inductively Coupled Plasma

    Energy Technology Data Exchange (ETDEWEB)

    DeKalb, E.L. and Edelson, M. C.

    1987-08-01

    Optical emission spectra from high-purity Np-237 were generated with a glovebox-enclosed inductively coupled plasma (ICP) source. Spectra covering the 230-700 nm wavelength range are presented along with general commentary on the methodology used in collecting the data. The Ames Laboratory Nuclear Safeguards and Security Program has been charged with the task of developing optical spectroscopic methods to analyze the composition of spent nuclear fuels. Such materials are highly radioactive even after prolonged 'cooling' and are chemically complex. Neptunium (Np) is a highly toxic by-product of nuclear power generation and is found, in low abundance, in spent nuclear fuels. This atlas of the optical emission spectrum of Np, as produced by an inductively coupled plasma (ICP) spectroscopic source, is part of a general survey of the ICP emission spectra of the actinide elements. The ICP emission spectrum of the actinides originates almost exclusively from the electronic relaxation of excited, singly ionized species. Spectral data on the Np ion emission spectrum (i.e., the Np II spectrum) have been reported by Tomkins and Fred [1] and Haaland [2]. Tomkins and Fred excited the Np II spectrum with a Cu spark discharge and identified 114 Np lines in the 265.5 - 436.3 nm spectral range. Haaland, who corrected some spectral line misidentifications in the work of Tomkins and Fred, utilized an enclosed Au spark discharge to excite the Np II spectrum and reported 203 Np lines within the 265.4 - 461.0 nm wavelength range.

  6. Mapping trapped atomic gas with spin-orbit coupling to quantum Rabi-like model

    OpenAIRE

    Hu, Haiping; Chen, Shu

    2013-01-01

    We construct a connection of the ultracold atomic system in a harmonic trap with Raman-induced spin-orbit coupling to the quantum Rabi-like model. By mapping the trapped atomic system to a Rabi-like model, we can get the exact solution of the Rabi-like model following the methods to solve the quantum Rabi model. The existence of such a mapping implies that we can study the basic model in quantum optics by using trapped atomic gases with spin-orbit coupling.

  7. Toward Comprehensive Physical/Chemical Understanding of the Circumstellar Environments - Simultaneous Probing of Each of the Ionized/Atomic/Molecular Gas and Dust Components

    Science.gov (United States)

    Ueta, Toshiya

    We propose to continue our successful investigations into simultaneous probing of each of the ionized/atomic/molecular gas and dust components in planetary nebulae using primarily far-IR broadband images and spatially-resolved spectroscopic data cubes obtained with the Herschel Space Observatory to enhance our understanding of the circumstellar environments. This research originally started as the Herschel Planetary Nebula Survey (HerPlaNS) - an open time 1 program of the Herschel Space Observatory - in which 11 high-excitation PNs were observed to study the nebular energetics that involves very hot X-ray emitting plasma to very cold dust grains, whose density ranges over 3 to 4 orders of magnitude and temperature ranges over 7 orders of magnitude. The HerPlaNS data include broadband maps, IFU spectral data cubes, and bolometer array spectral data cubes covering 50 to 670 microns. Because of the sheer volume and complexity of the data set, the original funding was exhausted almost exclusively to the initial data reduction and not much to the subsequent science analysis. However, we managed to perform a nearly full science analysis for one target, NGC 6781, for which the broadband maps confirm the nearly pole-on barrel structure of the amorphous carbonrich dust shell and the surrounding halo having temperatures of 26-40 K. We also demonstrated that spatially resolved far-IR line diagnostics would yield the (Te, ne) profiles, from which distributions of ionized, atomic, and molecular gases can be determined. Direct comparison of the dust and gas column mass maps constrained by the HerPlaNS data allowed to construct an empirical gas-to-dust mass ratio map, which shows a range of ratios with the median of 195 with a standard deviation of 110. The analysis also yielded estimates of the total mass of the shell to be 0.86 M_sun, consisting of 0.54 M_sun of ionized gas, 0.12 M_sun of atomic gas, 0.2 M_sun of molecular gas, and 0.004 M_sun of dust grains. These estimates

  8. Optical response of gas-phase atoms at less than $\\lambda/80$ from a dielectric surface

    CERN Document Server

    Whittaker, K A; Hughes, I G; Sargsyan, A; Sarkisyan, D; Adams, C S

    2014-01-01

    We present experimental observations of atom-light interactions within tens of nanometers (down to 11~nm) of a sapphire surface. Using photon counting we detect the fluorescence from of order one thousand Rb or Cs atoms, confined in a vapor with thickness much less than the optical excitation wavelength. The asymmetry in the spectral lineshape provides a direct read-out of the atom-surface potential. A numerical fit indicates a power-law $-C_{\\alpha}/r^{\\alpha}$ with $\\alpha=3.02\\pm0.06$ confirming that the van der Waals interaction dominates over other effects. The extreme sensitivity of our photon-counting technique may allow the search for atom-surface bound states.

  9. Atom Probe Analysis of Ex Situ Gas-Charged Stable Hydrides.

    Science.gov (United States)

    Haley, Daniel; Bagot, Paul A J; Moody, Michael P

    2017-01-30

    In this work, we report on the atom probe tomography analysis of two metallic hydrides formed by pressurized charging using an ex situ hydrogen charging cell, in the pressure range of 200-500 kPa (2-5 bar). Specifically we report on the deuterium charging of Pd/Rh and V systems. Using this ex situ system, we demonstrate the successful loading and subsequent atom probe analysis of deuterium within a Pd/Rh alloy, and demonstrate that deuterium is likely present within the oxide-metal interface of a native oxide formed on vanadium. Through these experiments, we demonstrate the feasibility of ex situ hydrogen analysis for hydrides via atom probe tomography, and thus a practical route to three-dimensional imaging of hydrogen in hydrides at the atomic scale.

  10. Warm ISM in the Sagittarius A Complex. I. Mid-J CO, atomic carbon, ionized atomic carbon, and ionized nitrogen sub-mm/FIR line observations with the Herschel-HIFI and NANTEN2/SMART telescopes

    Science.gov (United States)

    García, P.; Simon, R.; Stutzki, J.; Güsten, R.; Requena-Torres, M. A.; Higgins, R.

    2016-04-01

    Aims: We investigate the spatial and spectral distribution of the local standard of rest (LSR) velocity resolved submillimetre emission from the warm (25-90 K) gas in the Sgr A Complex, located in the Galactic centre. Methods: We present large-scale submillimetre heterodyne observations towards the Sgr A Complex covering ~300 arcmin2. These data were obtained in the frame of the Herschel EXtraGALactic guaranteed time key program (HEXGAL) with the Herschel-HIFI satellite and are complemented with submillimetre observations obtained with the NANTEN2/SMART telescope as part of the NANTEN2/SMART Central Nuclear Zone Survey. The observed species are CO(J = 4-3) at 461.0 GHz observed with the NANTEN2/SMART telescope, and [CI] 3P1-3P0 at 492.2 GHz, [CI] 3P2-3P1 at 809.3 GHz, [NII] 3P1-3P0 at 1461.1 GHz, and [CII] 2P3/2-2P1/2 at 1900.5 GHz observed with the Herschel-HIFI satellite. The observations are presented in a 1 km s-1 spectral resolution and a spatial resolution ranging from 46 arcsec to 28 arcsec. The spectral coverage of the three lower frequency lines is ±200 km s-1, while in the two high frequency lines, the upper LSR velocity limit is +94 km s-1 and +145 km s-1 for the [NII] and [CII] lines, respectively. Results: The spatial distribution of the emission in all lines is very widespread. The bulk of the carbon monoxide emission is found towards Galactic latitudes below the Galactic plane, and all the known molecular clouds are identified. Both neutral atomic carbon lines have their brightest emission associated with the +50 km s-1 cloud. Their spatial distribution at this LSR velocity describes a crescent-shape structure, which is probably the result of interaction with the energetic event (one or several supernovae explosions) that gave origin to the non-thermal Sgr A-East source. The [CII] and [NII] emissions have most of their flux associated with the thermal arched-filaments and the H region and bright spots in [CII] emission towards the central nuclear

  11. Constraining the dynamical importance of hot gas and radiation pressure in quasar outflows using emission line ratios

    CERN Document Server

    Stern, Jonathan; Zakamska, Nadia L; Hennawi, Joseph F

    2015-01-01

    Quasar feedback models often predict an expanding hot gas bubble which drives a galaxy-scale outflow. In many circumstances the hot gas is predicted to radiate inefficiently, making the hot bubble hard to observe directly. We present an indirect method to detect the presence of a hot bubble using hydrostatic photoionization models of the cold (10^4 K) line-emitting gas. These models assume that the cold gas is in pressure equilibrium with either the hot gas pressure or with the radiation pressure, whichever is larger. We compare our models with observations of the broad line region (BLR), the inner face of the dusty torus, the narrow line region (NLR), and the extended NLR, and thus constrain the hot gas pressure over a dynamical range of 10^5 in radius, from 0.1 pc to 10 kpc. We find that the emission line ratios observed in the average quasar spectrum are consistent with radiation-pressure-dominated models on all scales. On scales > L_AGN/c inferred for galaxy-scale outflows in luminous quasars. This appare...

  12. Determination and characterization of phytochelatins by liquid chromatography coupled with on line chemical vapour generation and atomic fluorescence spectrometric detection.

    Science.gov (United States)

    Bramanti, Emilia; Toncelli, Daniel; Morelli, Elisabetta; Lampugnani, Leonardo; Zamboni, Roberto; Miller, Keith E; Zemetra, Joseph; D'Ulivo, Alessandro

    2006-11-10

    Liquid chromatography (LC) coupled on line with UV/visible diode array detector (DAD) and cold vapour generation atomic fluorescence spectrometry (CVGAFS) has been developed for the speciation, determination and characterization of phytochelatins (PCs). The method is based on a bidimensional approach, e.g. on the analysis of synthetic PC solutions (apo-PCs and Cd(2+)-complexed PCs) (i) by size exclusion chromatography coupled to UV diode array detector (SEC-DAD); (ii) by the derivatization of PC -SH groups in SEC fractions by p-hydroxymercurybenzoate (PHMB) and the indirect detection of PC-PHMB complexes by reversed phase liquid chromatography coupled to atomic fluorescence detector (RPLC-CVGAFS). MALDI-TOF/MS (matrix assisted laser desorption ionization time of flight mass spectrometry) analysis of underivatized synthetic PC samples was performed in order have a qualitative information of their composition. Quantitative analysis of synthetic PC solutions has been performed on the basis of peak area of PC-PHMB complexes of the mercury specific chromatogram and calibration curve of standard solution of glutathione (GSH) complexed to PHMB (GS-PHMB). The limit of quantitation (LOQ) in terms of GS-PHMB complex was 90 nM (CV 5%) with an injection volume of 35 microL, corresponding to 3.2 pmol (0.97 ng) of GSH. The method has been applied to analysis of extracts of cell cultures from Phaeodactylum tricornutum grown in Cd-containing nutrient solutions, analysed by SEC-DAD-CVGAFS and RPLC-DAD-CVGAFS.

  13. National Assessment of Oil and Gas Project, Northern Alaska Province (001). Petroleum Systems and Geologic Assessment of Gas Hydrates in Northern Alaska – 2008. Limits of the Gas Hydrate stability zone contour lines

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The limits of Gas Hydrate (GH) stability zone contour lines (GH stability thickness zero) shown here is a geographic boundary defined and mapped on basis of U.S....

  14. Interaction of gas phase atomic hydrogen with Pt(111):Direct evidence for the formation of bulk hydrogen species

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Employing hot tungsten filament to thermal dissociate molecular hydrogen,we generated gas phase atomic hydrogen under ultra-high vacuum(UHV)conditions and investigated its interaction with Pt(111) surface.Thermal desorption spectroscopy(TDS)results demonstrate that adsorption of molecular hy- drogen on Pt(111)forms surface Had species whereas adsorption of atomic hydrogen forms not only surface Had species but also bulk Had species.Bulk Had species is more thermal-unstable than surface Had species on Pt(111),suggesting that bulk Had species is more energetic.This kind of weakly- adsorbed bulk Had species might be the active hydrogen species in the Pt-catalyzed hydrogenation reactions.

  15. Water O-H bond activation by gas-phase plutonium atoms: reaction mechanisms and ab initio molecular dynamics study.

    Science.gov (United States)

    Li, Peng; Niu, Wenxia; Gao, Tao; Wang, Hongyan

    2014-10-06

    A thorough description of the reaction mechanisms, taking into account different possible spin states, offers insights into the gas-phase reaction of plutonium atoms with water. Two possible reactions (isomerization and dehydrogenation) are presented. These reactions are found to be exothermic, with the best thermochemical conditions observed for the dehydrogenation reaction at around 23.5 kcal mol(-1). The nature of the chemical-bonding evolution along the reaction pathways are investigated by employing various methods including electron localization function, atoms in molecules, and Mayer bond order. Total, partial, and overlap population density of state diagrams and analyses are also presented. Reaction rates at elevated temperatures (T=298-2 000 K) are calculated by using variational transition-state theory with one-dimensional tunneling effects. In dynamics simulations, only the dehydrogenation reaction is observed, and found to be in good agreement with experimental values.

  16. Thermal Analysis in Gas Insulated Transmission Lines Using an Improved Finite-Element Model

    Directory of Open Access Journals (Sweden)

    Ling LI

    2013-01-01

    Full Text Available  In this paper, an improved finite element (FE model is proposed to investigate the temperature distribution in gas insulated transmission lines (GILs. The solution of joule losses in eddy current field analysis is indirectly coupled into fluid and thermal fields. As is different from the traditional methods, the surrounding air of the GIL is involved in the model to avoid constant convective heat transfer coefficient, thus multiple species transport technique is employed to deal with the problem of two fluid types in a single model. In addition, the temperature dependent electrical and thermal properties of the materials are considered. The steady-state and transient thermal analysis of the GIL are performed separately with the improved model. The corresponding temperature distributions are compared with experimental results reported in the literature.

  17. The formation of IRIS diagnostics V. A quintessential model atom of C II and general formation properties of the C II lines at 133.5 nm

    CERN Document Server

    Rathore, Bhavna

    2015-01-01

    The 133.5 nm lines are important observables for the NASA/SMEX mission Interface Region Imaging Spectrograph (IRIS). To make 3D non-LTE radiative transfer computationally feasible it is crucial to have a model atom with as few levels as possible while retaining the main physical processes. We here develop such a model atom and we study the general formation properties of the C II lines. We find that a nine-level model atom of C I-C III with the transitions treated assuming complete frequency redistribution (CRD) suffices to describe the 133.5 nm lines. 3D scattering effects are important for the intensity in the core of the line. The lines are formed in the optically thick regime. The core intensity is formed in layers where the temperature is about 10kK at the base of the transition region. The lines are 1.2-4 times wider than the atomic absorption profile due to the formation in the optically thick regime. The smaller opacity broadening happens for single peak intensity profiles where the chromospheric temp...

  18. Development of an automated high temperature valveless injection system for on-line gas chromatography

    Directory of Open Access Journals (Sweden)

    N. M. Kreisberg

    2014-07-01

    Full Text Available A reliable method of sample introduction is presented for on-line gas chromatography with a special application to in-situ field portable atmospheric sampling instruments. A traditional multi-port valve is replaced with a controlled pressure switching device that offers the advantage of long term reliability and stable sample transfer efficiency. An engineering design model is presented and tested that allows customizing the interface for other applications. Flow model accuracy is within measurement accuracy (1% when parameters are tuned for an ambient detector and 15% accurate when applied to a vacuum based detector. Laboratory comparisons made between the two methods of sample introduction using a thermal desorption aerosol gas chromatograph (TAG show approximately three times greater reproducibility maintained over the equivalent of a week of continuous sampling. Field performance results for two versions of the valveless interface used in the in-situ instrument demonstrate minimal trending and a zero failure rate during field deployments ranging up to four weeks of continuous sampling. Extension of the VLI to dual collection cells is presented with less than 3% cell-to-cell carry-over.

  19. Storage and retrieval of (3+1)-dimensional weak-light bullets and vortices in a coherent atomic gas

    CERN Document Server

    Chen, Zhiming; Li, Hui-jun; Hang, Chao; Huang, Guoxiang

    2016-01-01

    A robust light storage and retrieval (LSR) in high dimensions is highly desirable for light and quantum information processing. However, most schemes on LSR realized up to now encounter problems due to not only dissipation, but also dispersion and diffraction, which make LSR with a very low fidelity. Here we propose a scheme to achieve a robust storage and retrieval of weak nonlinear high-dimensional light pulses in a coherent atomic gas via electromagnetically induced transparency. We show that it is available to produce stable (3+1)-dimensional light bullets and vortices, which have very attractive physical property and are suitable to obtain a robust LSR in high dimensions.

  20. Warm gas in the rotating disk of the Red Rectangle: accurate models of molecular line emission

    CERN Document Server

    Bujarrabal, V

    2013-01-01

    We aim to study the excitation conditions of the molecular gas in the rotating disk of the Red Rectangle, the only post-Asymptotic-Giant-Branch object in which the existence of an equatorial rotating disk has been demonstrated. For this purpose, we developed a complex numerical code that accurately treats radiative transfer in 2-D, adapted to the study of molecular lines from rotating disks. We present far-infrared Herschel/HIFI observations of the 12CO and 13CO J=6-5, J=10-9, and J=16-15 transitions in the Red Rectangle. We also present our code in detail and discuss the accuracy of its predictions, from comparison with well-tested codes. Theoretical line profiles are compared with the empirical data to deduce the physical conditions in the disk by means of model fitting. We conclude that our code is very efficient and produces reliable results. The comparison of the theoretical predictions with our observations reveals that the temperature of the Red Rectangle disk is typically ~ 100-150 K, about twice as h...

  1. Investigations of Biofilm-Forming Bacterial Cells by Atomic Force Microscopy Prior to and Following Treatment from Gas Discharge Plasmas

    Science.gov (United States)

    Vandervoort, K. G.; Joaquin, J. C.; Kwan, C.; Bray, J. D.; Torrico, R.; Abramzon, N.; Brelles-Marino, G.

    2007-03-01

    We present investigations of biofilm-forming bacteria before and after treatment from gas discharge plasmas. Gas discharge plasmas represent a way to inactivate bacteria under conditions where conventional disinfection methods are often ineffective. These conditions involve bacteria in biofilm communities, where cooperative interactions between cells make organisms less susceptible to standard killing methods. Rhizobium gallicum and Chromobacterium violaceum were imaged before and after plasma treatment using an atomic force microscope (AFM). In addition, cell wall elasticity was studied by measuring force distance curves as the AFM tip was pressed into the cell surface. Results for cell surface morphology and micromechanical properties for plasma treatments lasting from 5 to 60 minutes were obtained and will be presented.

  2. Parametric performance analysis of steam-injected gas turbine with a thermionic-energy-converter-lined combustor

    Science.gov (United States)

    Choo, Y. K.; Burns, R. K.

    1982-01-01

    The performance of steam-injected gas turbines having combustors lined with thermionic energy converters (STIG/TEC systems) was analyzed and compared with that of two baseline systems; a steam-injected gas turbine (without a TEC-lined combustor) and a conventional combined gas turbine/steam turbine cycle. Common gas turbine parameters were assumed for all of the systems. Two configurations of the STIG/TEC system were investigated. In both cases, steam produced in an exhaust-heat-recovery boiler cools the TEC collectors. It is then injected into the gas combustion stream and expanded through the gas turbine. The STIG/TEC system combines the advantage of gas turbine steam injection with the conversion of high-temperature combustion heat by TEC's. The addition of TEC's to the baseline steam-injected gas turbine improves both its efficiency and specific power. Depending on system configuration and design parameters, the STIG/TEC system can also achieve higher efficiency and specific power than the baseline combined cycle.

  3. Probing 2D Quantum Turbulence in Atomic Superfluid Gas using Bragg Scattering

    CERN Document Server

    Seo, Sang Won; Kim, Joon Hyun; Shin, Yong-il

    2016-01-01

    We demonstrate the use of spatially resolved Bragg spectroscopy for detection of the quantum vortex circulation signs in an atomic Bose-Einstein condensate (BEC). High-velocity atoms near the vortex cores are resonantly scattered from the BEC, and the vortex signs are determined from the scattered atom positions relative to the corresponding vortex cores. Using this method, we investigate decaying 2D quantum turbulence in a highly oblate BEC at temperatures of $\\sim 0.5 T_c$, where $T_c$ is the critical temperature of the trapped sample. Clustering of like-sign vortices is not observed; rather, the measured vortex configurations reveal weak pair correlations between the vortices and antivortices in the turbulent BEC. Our Bragg scattering method enables a direct experimental study of 2D quantum turbulence in BECs.

  4. Investigations on the on-line determination of metals in air flows by capacitively coupled microwave plasma atomic emission spectrometry

    Science.gov (United States)

    Seelig, M.; Broekaert, J. A. C.

    2001-09-01

    Plasma optical emission spectrometry with a capacitively coupled microwave plasma (CMP) operated with air has been investigated with respect to its possibilities for real-time environmental monitoring of combustion processes. The unique feature is the possibility to operate the CMP with air as working gas, as is usually the case in exhaust gases of combustion processes. The CMP also is shown to be stable in the presence of large amounts of water and CO 2, which makes this source ideally suitable for this purpose. The detection limits obtained for the environmentally relevant elements Cd, Co, Cr, Fe, Mg, Ni and Pb show the possibility to monitor directly heavy metals in air in an on-line mode and down to the 2-160-μg m -3 level. These detection limits are generally lower than the threshold limit values of the 'Federal Law for Immission Protection' in Germany in the gaseous effluents of industrial plants. In order to investigate the influence of the water loading (32-222 g m -3) on the detection limits a comparison of results obtained with three different nebulizers (Légère nebulizer, hydraulic high-pressure nebulizer and ultrasonic nebulizer) was made, with which aerosols with different water loading are entered into the plasma. For the hydraulic high-pressure nebulizer and the ultrasonic nebulizer no desolvation unit was found to be necessary. It was shown that especially for elements with lines having high excitation energy (Cd) or for which ion lines are used (Mg II) the increase in water loading deteriorates the detection limits. The rotational temperatures ( Trot) and excitation temperatures ( Texe) in the case of different amounts of water are of the order of 3700-4900 K and 4700-7100 K, respectively. The temperatures show that changes in the geometry and temperature distribution in the case of Trot but also the values of Texe themselves are responsible for this increase in detection limits. Furthermore, different amounts of CO 2 mixed to the working gas (3

  5. Progress on the Study of Atomic and Molecular Gas in Interstellar Medium%星系中分子气体和原子气体的研究进展

    Institute of Scientific and Technical Information of China (English)

    富坚

    2012-01-01

    Molecular gas (mainly H2 molecule) and atomic gas (mainly HI atom) are very important baryonic components in interstellar medium, and they play significant roles in various kinds of physical processes in galaxies, including gas cooling and infall, star formation, metal producing, supernova reheating and feedback. It is generally considered that stars form in giant molecular clouds, and atomic gas is the reservoir of the molecular clouds. In recent years, observations give more and more results on molecular and atomic gas with the development of observational technology. Atomic gas component in nearby galaxies at low redshift is observed through 21 cm radio emission by neutral hydrogen atoms. 21 cm HI surveys provide a lot of information about the neutral gas components in galaxies at low redshift. Some famous HI survey in recent years are HIPASS, HIJASS, WSRT, ALFALFA, THINGS etc. For galaxies at redshift higher than 0.2, people usually use DLA absorbers to observe the HI gas components indirectly. Because of the symmetric structure, molecular hydrogen H2 components cannot be directly observed, and the molecular gas is observed through carbon monoxide or some other molecules as tracers. Some famous CO observations in recent years are FCRAO, COLD GASS, BIMA SONG, HERACLES. Based on these observations, people get the H2 properties for the local galaxies including the H2 mass functions at z = 0, the surface density profiles of molecular gas etc. Combining with the star formation rate observations of these galaxies, some astronomers find that the star formation rate correlates with the molecular components more tightly than total cold gas components. With the advance of observational studies along this line, more and more galaxy formation models have include the molecular and neutral gas components. There are mainly two aspects on the transition of these two components. One is on the transition between atomic and molecular gas in ISM, and the other is the semi

  6. Formation of globular clusters in atomic-cooling halos via rapid gas condensation and fragmentation during the epoch of reionization

    CERN Document Server

    Kimm, Taysun; Rosdahl, Joakim; Yi, Sukyoung

    2015-01-01

    We investigate the formation of metal-poor globular clusters (GCs) at the center of two dark matter halos with $M_{halo}\\sim4\\times10^7\\,M_\\odot$ at $z>10$ using cosmological radiation-hydrodynamics simulations. We find that very compact ($\\lesssim$ 1 pc) and massive ($\\sim6\\times10^5\\,M_\\odot$) clusters form rapidly when pristine gas collapses isothermally with the aid of efficient Ly$\\alpha$ emission during the transition from molecular-cooling halos to atomic-cooling halos. Because the local free-fall time of dense star-forming gas is very short ($\\ll 1\\,{\\rm Myr}$), a large fraction of the collapsed gas is turned into stars before stellar feedback processes blow out the gas and shut down star formation. Although the early stage of star formation is limited to a small region of the central star-forming disk, we find that the disk quickly fragments due to metal enrichment from supernovae. Sub-clusters formed in the fragmented clouds eventually merge with the main cluster at the center. We estimate using a s...

  7. Three—body collisions involving Na(3P),Rb(5S) and buffer gas atoms

    Institute of Scientific and Technical Information of China (English)

    沈异凡; 李万兴; 等

    1996-01-01

    Energy pooling in the Na-Rb vapor mixture has been investigated.While some kind of buffer gas is introduced into the cell the peculiar features appear.The buffer gas enhances the energy transfer betwwen Na(3P) and Rb(5S),which can be detected through the effects induced on the highly excited states populated by the Na(3P)/Rb(5P) and Rb(5P)/Rb(5P) collisions.

  8. Evolution of the atomic and molecular gas content of galaxies in dark matter haloes

    NARCIS (Netherlands)

    Popping, Gergö; Behroozi, Peter S.; Peeples, Molly S.

    2015-01-01

    We present a semi-empirical model to infer the atomic and molecular hydrogen content of galaxies as a function of halo mass and time. Our model combines the star formation rate (SFR)-halo mass-redshift relation (constrained by galaxy abundances) with inverted SFR-surface density relations to infer g

  9. Pulsed excitation of Rydberg-atom-pair states in an ultracold Cs gas

    CERN Document Server

    Saßmannshausen, Heiner; Deiglmayr, Johannes

    2015-01-01

    Pulsed laser excitation of a dense ultracold Cs vapor has been used to study the pairwise interactions between Cs atoms excited to $n$p$_{3/2}$ Rydberg states of principal quantum numbers in the range $n=22-36$. Molecular resonances were observed that correspond to excitation of Rydberg-atom-pair states correlated not only to the $n$p$_{3/2}+n$p$_{3/2}$ dissociation asymptotes, but also to $n$s$_{1/2}+(n+1)$s$_{1/2}$, $n$s$_{1/2}+n'$f$_{j}$, and $(n-4)$f$_{j}+(n-3)$f$_{j}$ $(j=5/2,7/2)$ dissociation asymptotes. These pair resonances are interpreted as arising from dipole-dipole, and higher long-range-interaction terms between the Rydberg atoms on the basis of i) their spectral positions, ii) their response to static and pulsed electric fields, and iii) millimeter-wave spectra between pair states correlated to different pair-dissociation asymptotes. The Rydberg-atom--pair states were found to spontaneously decay by Penning ionization and the dynamics of the ionization process were investigated during the first...

  10. Rate of reaction of dimethylmercury with oxygen atoms in the gas phase

    DEFF Research Database (Denmark)

    Egsgaard, Helge

    1986-01-01

    The rate constant for the reaction of atomic oxygen (O(3P)) with dimethylmercury has been measured at room temperature at a pressure of about 1 Torr using a fast flow system with electron paramagnetic resonance and mass spectrometric detection. Some reaction products were identified. The rate...

  11. Carbon nanotubes randomly decorated with gold clusters: from nano{sup 2}hybrid atomic structures to gas sensing prototypes

    Energy Technology Data Exchange (ETDEWEB)

    Charlier, J-C; Zanolli, Z [Unite de Physico-Chimie et de Physique des Materiaux (PCPM), European Theoretical Spectroscopy Facility (ETSF), Universite Catholique de Louvain, Place Croix du Sud 1, B-1348 Louvain-la-Neuve (Belgium); Arnaud, L; Avilov, I V; Felten, A; Pireaux, J-J [Centre de Recherche en Physique de la Matiere et du Rayonnement (PMR-LISE), Facultes Universitaires Notre-Dame de la Paix, 61 Rue de Bruxelles, B-5000 Namur (Belgium); Delgado, M [Sensotran, s.l., Avenida Remolar 31, E-08820 El Prat de Llobregat, Barcelona (Spain); Demoisson, F; Reniers, F [Service de Chimie Analytique et Chimie des Interfaces (CHANI), Universite Libre de Bruxelles, Faculte des Sciences, CP255, Boulevard du Triomphe 2, B-1050 Bruxelles (Belgium); Espinosa, E H; Ionescu, R; Leghrib, R; Llobet, E [Department of Electronic Engineering, Universitat Rovira i Virgili, Avenida Paisos Catalans 26, E-43007 Tarragona (Spain); Ewels, C P; Suarez-Martinez, I [Institut des Materiaux Jean Rouxel (IMN), Universite de Nantes, 2 rue de la Houssiniere-BP 32229, F-44322 Nantes Cedex 3 (France); Guillot, J; Mansour, A; Migeon, H-N [Departement Science et Analyse des Materiaux, Centre de Recherche Public-Gabriel Lippmann, rue du Brill 41, L-4422 Belvaux (Luxembourg); Watson, G E, E-mail: jean-jacques.pireaux@fundp.ac.b [Vega Science Trust, Unit 118, Science Park SQ, Brighton, BN1 9SB (United Kingdom)

    2009-09-16

    Carbon nanotube surfaces, activated and randomly decorated with metal nanoclusters, have been studied in uniquely combined theoretical and experimental approaches as prototypes for molecular recognition. The key concept is to shape metallic clusters that donate or accept a fractional charge upon adsorption of a target molecule, and modify the electron transport in the nanotube. The present work focuses on a simple system, carbon nanotubes with gold clusters. The nature of the gold-nanotube interaction is studied using first-principles techniques. The numerical simulations predict the binding and diffusion energies of gold atoms at the tube surface, including realistic atomic models for defects potentially present at the nanotube surface. The atomic structure of the gold nanoclusters and their effect on the intrinsic electronic quantum transport properties of the nanotube are also predicted. Experimentally, multi-wall CNTs are decorated with gold clusters using (1) vacuum evaporation, after activation with an RF oxygen plasma and (2) colloid solution injected into an RF atmospheric plasma; the hybrid systems are accurately characterized using XPS and TEM techniques. The response of gas sensors based on these nano{sup 2}hybrids is quantified for the detection of toxic species like NO{sub 2}, CO, C{sub 2}H{sub 5}OH and C{sub 2}H{sub 4}.

  12. Star-forming dwarf galaxies in the Virgo cluster: the link between molecular gas, atomic gas, and dust

    CERN Document Server

    Grossi, M; Bizzocchi, L; Giovanardi, C; Bomans, D; Coelho, B; De Looze, I; Gonçalves, T S; Hunt, L K; Leonardo, E; Madden, S; Menéndez-Delmestre, K; Pappalardo, C; Riguccini, L

    2016-01-01

    We present $^{12}$CO(1-0) and $^{12}$CO(2-1) observations of a sample of 20 star-forming dwarfs selected from the Herschel Virgo Cluster Survey, with oxygen abundances ranging from 12 + log(O/H) ~ 8.1 to 8.8. CO emission is observed in ten galaxies and marginally detected in another one. CO fluxes correlate with the FIR 250 $\\mu$m emission, and the dwarfs follow the same linear relation that holds for more massive spiral galaxies extended to a wider dynamical range. We compare different methods to estimate H2 molecular masses, namely a metallicity-dependent CO-to-H2 conversion factor and one dependent on H-band luminosity. The molecular-to-stellar mass ratio remains nearly constant at stellar masses <~ 10$^9$ M$_{\\odot}$, contrary to the atomic hydrogen fraction, M$_{HI}$/M$_*$, which increases inversely with M$_*$. The flattening of the M$_{H_2}$/M$_*$ ratio at low stellar masses does not seem to be related to the effects of the cluster environment because it occurs for both HI-deficient and HI-normal dwa...

  13. The shocked gas of the BHR71 outflow observed by Herschel: indirect evidence for an atomic jet

    Science.gov (United States)

    Benedettini, M.; Gusdorf, A.; Nisini, B.; Lefloch, B.; Anderl, S.; Busquet, G.; Ceccarelli, C.; Codella, C.; Leurini, S.; Podio, L.

    2017-01-01

    Context. In the BHR71 region, two low-mass protostars IRS1 and IRS2 drive two distinguishable outflows. They constitute an ideal laboratory to investigate both the effects of shock chemistry and the mechanisms that led to their formation. Aims: We aim to define the global morphology of the warm gas component of the BHR71 outflow and at modelling its shocked component. Methods: We present the first far infrared Herschel images of the BHR71 outflows system in the CO (14-13), H2O (221-110), H2O (212-101) and [O i] 145 μm transitions, revealing the presence of several knots of warm, shocked gas associated with the fast outflowing gas. In two of these knots we performed a detailed study of the physical conditions by comparing a large set of transitions from several molecules to a grid of shock models. Results: The Herschel lines ratios in the outflow knots are quite similar, showing that the excitation conditions of the fast moving gas do not change significantly within the first 0.068 pc of the outflow, apart at the extremity of the southern blue-shifted lobe that is expanding outside the parental molecular cloud. Rotational diagram, spectral line profile and LVG analysis of the CO lines in knot A show the presence of two gas components: one extended, cold (T 80 K) and dense (n(H2) = 3 × 105-4 × 106 cm-3) and another compact (18''), warm (T = 1700-2200 K) with slightly lower density (n(H2) = 2 × 104-6 × 104 cm-3). In the two brightest knots (where we performed shock modelling) we found that H2 and CO are well fitted with non-stationary (young) shocks. These models, however, significantly underestimate the observed fluxes of [O i] and OH lines, but are not too far off those of H2O, calling for an additional, possibly dissociative, J-type shock component. Conclusions: Our modelling indirectly suggests that an additional shock component exists, possibly a remnant of the primary jet. Direct, observational evidence for such a jet must be searched for. Herschel is an

  14. The reaction of nitromethane with hydrogen and deuterium atoms in the gas phase. A mechanistic study

    DEFF Research Database (Denmark)

    Lund Thomsen, E.; Nielsen, O.J.; Egsgaard, H.

    1993-01-01

    The mechanism of the reaction between H and CH3NO2, has been studied in a discharge flow system using electron paramagnetic resonance and modulated molecular beam mass spectrometry for the detection of reactants and products. Deuterium atoms have, in addition to CD3NO2, been used to support...... the proposed reaction mechanism. The reaction was studied with the atomic reactant in slight excess at 298 K and a total pressure of 2 Torr. Two concurrent reaction channels: (1a) H+CH3NO2-->HONO+.CH3 and (1b) H+CH3NO2-->CH3NO+.OH were observed. The branching ratio, k1a/(k1a+k1b), is 0.7+/-0.2....

  15. Ultracold chemical reactions of a single Rydberg atom in a dense gas

    CERN Document Server

    Schlagmüller, Michael; Engel, Felix; Kleinbach, Kathrin S; Böttcher, Fabian; Westphal, Karl M; Gaj, Anita; Löw, Robert; Hofferberth, Sebastian; Pfau, Tilman; Pérez-Ríos, Jesús; Greene, Chris H

    2016-01-01

    Within a dense environment ($\\rho \\approx 10^{14}\\,$atoms/cm$^3$) at ultracold temperatures ($T 140$ compared to $1\\,\\mu\\text{s}$ at $n=90$. In addition, a second observed reaction mechanism, namely Rb$_2^+$ molecule formation, was studied. Both reaction products are equally probable for $n=40$ but the fraction of Rb$_2^+$ created drops to below 10$\\,$% for $n\\ge90$.

  16. Ubiquitous argonium (ArH$^+$) in the diffuse interstellar medium -- a molecular tracer of almost purely atomic gas

    CERN Document Server

    Schilke, Peter; Mueller, Holger S P; Comito, Claudia; Bergin, Edwin A; Lis, Dariusz C; Gerin, Maryvonne; Black, John H; Wolfit, Mark; Indriolo, Nick; Pearson, John C; Menten, Karl M; Winkel, Benjamin; Sanchez-Monge, Alvaro; Moeller, Thomas; Godard, Benjamin; Falgarone, Edith

    2014-01-01

    We describe the assignment of a previously unidentified interstellar absorption line to ArH$^+$ and discuss its relevance in the context of hydride absorption in diffuse gas with a low H$_2$ fraction. The column densities along several lines of sight are determined and discussd in the framework of chemical models. The column densities of ArH$^+$ are compared to those of other species, tracing interstellar medium (ISM) components with different H$_2$ abundances. Chemical models are constructed, taking UV radiation and cosmic ray ionization into account. Due to the detection of two isotopologues, $^{36}$ArH$^+$ and $^{38}$ArH$^+$, we are confident about the carrier assignment to ArH$^+$. NeH$^+$ is not detected with a limit of [NeH$^+$]/[ArH$^+$] $\\le$ 0.1. The derived column densities agree well with the predictions of chemical models. ArH$^+$ is a unique tracer of gas with a fractional H$_2$ abundance of $10^{-4}- 10^{-3}$ and shows little correlation with H$_2$O$^+$, which traces gas with a fractional H$_2$ ...

  17. C IV and He II line emission of Lyman α blobs: powered by shock-heated gas

    Science.gov (United States)

    Cabot, Samuel H. C.; Cen, Renyue; Zheng, Zheng

    2016-10-01

    Utilizing ab initio ultrahigh resolution hydrodynamical simulations, we investigate the properties of the interstellar and circumgalactic medium of Lyα blobs (LABs) at z = 3, focusing on three important emission lines: Lyα 1216 Å, He II 1640 Å and C IV 1549 Å. Their relative strengths provide a powerful probe of the thermodynamic properties of the gas when confronted with observations. By adjusting the dust attenuation effect using one parameter and matching the observed size-luminosity relation of LABs using another parameter, we show that our simulations can reproduce the observed C IV/Lyα and He II/Lyα ratios adequately. This analysis provides the first successful physical model to account for simultaneously the LAB luminosity function, luminosity-size relation and the C IV/Lyα and He II/Lyα ratios, with only two parameters. The physical underpinning for this model is that, in addition to the stellar component for the Lyα emission, the Lyα and C IV emission lines due to shock-heated gas are primarily collisional excitation driven and the He II emission line collisional ionization driven. We find that the density, temperature and metallicity of the gas responsible for each emission line is significantly distinct, in a multiphase interstellar and circumgalactic medium that is shock heated primarily by supernovae and secondarily by gravitational accretion of gas.

  18. C IV and He II Line Emission of Lyman Alpha Blobs: Powered by Shock Heated Gas

    CERN Document Server

    Cabot, Samuel H C; Zheng, Zheng

    2016-01-01

    Utilizing {\\it ab initio} ultra-high resolution hydrodynamical simulations, we investigate the properties of the interstellar and circum-galactic medium of Ly$\\alpha$ Blobs (LABs) at $z=3$, focusing on three important emission lines: Ly$\\alpha$ 1216\\AA, \\heii 1640\\AA\\ and \\civ 1449\\AA. Their relative strengths provide a powerful probe of the thermodynamic properties of the gas when confronted with observations. By adjusting the dust attenuation effect using one parameter and matching the observed size-luminosity relation of LABs using another parameter, we show that our simulations can reproduce the observed \\civ/\\lya\\ and \\heii/\\lya\\ ratios adequately. This analysis provides the first successful physical model to account for simultaneously the LAB luminosity function, luminosity-size relation, and the \\civ/Ly$\\alpha$ and \\heii/Ly$\\alpha$ ratios, with only two parameters. The physical underpinning for this model is that, in addition to the stellar component for the \\lya\\ emission, the \\lya\\ and \\civ\\ emission...

  19. Integration of Gas Nitrocarburising and Oxidising in a Mass Production Line for Brake Pistons

    Institute of Scientific and Technical Information of China (English)

    Gero Walkowiak; Dieter M(u)ller; Uwe Zeibig

    2004-01-01

    The combination of wear- and corrosion resistance is a demand to a multitude of automotive parts. Several metallic coatings as hard/soft chromium or electroless nickel have been the conventional surface protection e.g. on parts as brake pistons and shock absorber or gas spring piston rods. The Corr-I-Dur(R) process - a special gasnitrocarburising and oxidising technology - has a huge potential not only in substituting those coatings but also in delivering surfaces with higher quality.The benefits of the replacement of soft chromium with Corr-I-Dur(R) and the implementation of the process in the customers production line with an annual capacity of 17 million brake pistons is described in this presentation. Starting with the demands on wear- and corrosion resistance the way of process development and the design of applicative equipment is shown. The result is a tailor-made surface solution with superior quality for deep drawn brake pistons. Two main disadvantagesoutgassing of the chromium layer and reduced corrosion resistance on the inner diameter - are eliminated by the replacement with Corr-I-Dur(R). The process-sure achievement of enhanced corrosion resistance, uniform layer thickness, negligible distortion as well as environmental and economical advantages make Corr-I-Dur(R) an excellence choice for this application.

  20. Stark spectroscopy of atomic hydrogen balmer-alpha line for electric field measurement in plasmas by saturation spectroscopy

    Science.gov (United States)

    Nishiyama, S.; Katayama, K.; Nakano, H.; Goto, M.; Sasaki, K.

    2016-09-01

    Detailed structures of electric fields in sheath and pre-sheath regions of various plasmas are interested from the viewpoint of basic plasma physics. Several researchers observed Stark spectra of Doppler-broadened Rydberg states to evaluate electric fields in plasmas; however, these measurements needed high-power, expensive tunable lasers. In this study, we carried out another Stark spectroscopy with a low-cost diode laser system. We applied saturation spectroscopy, which achieves a Doppler-free wavelength resolution, to observe the Stark spectrum of the Balmer-alpha line of atomic hydrogen in the sheath region of a low-pressure hydrogen plasma. The hydrogen plasma was generated in an ICP source which was driven by on-off modulated rf power at 20 kHz. A planar electrode was inserted into the plasma. Weak probe and intense pump laser beams were injected into the plasma from the counter directions in parallel to the electrode surface. The laser beams crossed with a small angle above the electrode. The observed fine-structure spectra showed shifts, deformations, and/or splits when varying the distance between the observation position and the electrode surface. The detection limit for the electric field was estimated to be several tens of V/cm.

  1. On-line preconcentration of copper as its pyrocatechol violet complex on Chromosorb 105 for flame atomic absorption spectrometric determinations

    Energy Technology Data Exchange (ETDEWEB)

    Buke, Berrin [Chemistry Department, Science and Arts Faculty, Pamukkale University, 20020 Denizli (Turkey); Divrikli, Umit [Chemistry Department, Science and Arts Faculty, Pamukkale University, 20020 Denizli (Turkey)], E-mail: udivrikli@pamukkale.edu.tr; Soylak, Mustafa [Chemistry Department, Science and Arts Faculty, Erciyes University, 38039 Kayseri (Turkey); Elci, Latif [Chemistry Department, Science and Arts Faculty, Pamukkale University, 20020 Denizli (Turkey)

    2009-04-30

    An on-line solid phase extraction method for the preconcentration and determination of Cu(II) by flame atomic absorption spectrometry (FAAS) has been described. It is based on the adsorption of copper(II) ion onto a home made mini column of Chromosorb 105 resin loaded with pyrocatechol violet at the pH range of 5.0-8.0, then eluted with 1 mol L{sup -1} HNO{sub 3}. Several parameters, such as pH of the sample solution, amount of Chromosorb 105 resin, volume of sample and eluent, type of eluent, flow rates of sample and eluent, governing the efficiency and throughput of the method were evaluated. The concentration of the copper ion detected after preconcentration was in agreement with the added amount. At optimized conditions, for 15 min of preconcentration time (30 mL of sample volume), the system achieved a detection limit of 0.02 {mu}g L{sup -1}, with relative standard deviation 1.1% at 0.03 {mu}g mL{sup -1} copper. The present method was found to be applicable to the preconcentration of Cu(II) in natural water samples.

  2. A Narrow-Linewidth Atomic Line Filter for Free Space Quantum Key Distribution under Daytime Atmospheric Conditions

    Science.gov (United States)

    Brown, Justin; Woolf, David; Hensley, Joel

    2016-05-01

    Quantum key distribution can provide secure optical data links using the established BB84 protocol, though solar backgrounds severely limit the performance through free space. Several approaches to reduce the solar background include time-gating the photon signal, limiting the field of view through geometrical design of the optical system, and spectral rejection using interference filters. Despite optimization of these parameters, the solar background continues to dominate under daytime atmospheric conditions. We demonstrate an improved spectral filter by replacing the interference filter (Δν ~ 50 GHz) with an atomic line filter (Δν ~ 1 GHz) based on optical rotation of linearly polarized light through a warm Rb vapor. By controlling the magnetic field and the optical depth of the vapor, a spectrally narrow region can be transmitted between crossed polarizers. We find that the transmission is more complex than a single peak and evaluate peak transmission as well as a ratio of peak transmission to average transmission of the local spectrum. We compare filters containing a natural abundance of Rb with those containing isotopically pure 87 Rb and 85 Rb. A filter providing > 95 % transmission and Δν ~ 1.1 GHz is achieved.

  3. Gamma rays from atomic and molecular gas in the large complex of clouds in Orion and Monoceros

    Science.gov (United States)

    Bloemen, J. B. G. M.; Caraveo, P. A.; Hermsen, W.; Lebrun, F.; Maddalena, R. J.; Strong, A. W.; Thaddeus, P.

    1984-01-01

    A comparison of COS-B gamma-ray observations of the large complex of interstellar clouds in Orion and Monoceros with the Columbia CO and Berkeley H I surveys of this region reveals a good correlation between gamma-ray emission and total gas distribution. The observed gamma-ray emission is explainable in terms of interactions of cosmic rays that are uniformly distributed in this region with the interstellar gas. The correlation is used as the basis of a calibration of the ratio between H2 column density and the integrated CO line intensity; the value of (2.6 + or - 1.2) X 10 to the 20th mol/sq cm K km s thereby obtained is consistent with the value derived from a similar analysis for the inner galaxy.

  4. On-line sample processing involving microextraction techniques as a front-end to atomic spectrometric detection for trace metal assays: A review

    Energy Technology Data Exchange (ETDEWEB)

    Miró, Manuel, E-mail: manuel.miro@uib.es [FI-TRACE Group, Department of Chemistry, Faculty of Sciences, University of the Balearic Islands, E-07122 Palma de Mallorca, Illes Balears (Spain); Hansen, Elo Harald [Granåsen 93, DK-2800 Kgs. Lyngby (Denmark)

    2013-06-11

    Graphical abstract: -- Highlights: •Role of flow injection in automation of microextraction techniques for metal assays. •On-line coupling of liquid phase microextraction (LPME) to atomic spectrometry. •Critical evaluation of on-line single drop and dispersive LPME. •On-line coupling of micro-solid phase extraction (μSPE) to atomic spectrometry. •Critical appraisal of magnetic/carbon nanoparticles and biomass for on-line μSPE. -- Abstract: Within the last decade, liquid-phase microextraction (LPME) and micro-solid phase extraction (μSPE) approaches have emerged as substitutes for conventional sample processing procedures for trace metal assays within the framework of green chemistry. This review surveys the progress of the state of the art in simplification and automation of microextraction approaches by harnessing to the various generations of flow injection (FI) as a front end to atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS) or inductively coupled plasma atomic emission spectrometry or mass spectrometry (ICP-AES/MS). It highlights the evolution of flow injection analysis and related techniques as vehicles for appropriate sample presentation to the detector and expedient on-line matrix separation and pre-concentration of trace levels of metals in troublesome matrices. Rather than being comprehensive this review is aimed at outlining the pros and cons via representative examples of recent attempts in automating green sample preparation procedures in an FI or sequential injection (SI) mode capitalizing on single-drop microextraction, dispersive liquid-phase microextraction and advanced sorptive materials including carbon and metal oxide nanoparticles, ion imprinted polymers, superparamagnetic nanomaterials and biological/biomass sorbents. Current challenges in the field are identified and the synergetic combination of flow analysis, nanotechnology and metal-tagged biomolecule detection is envisaged.

  5. Discovery of Molecular Gas around HD 131835 in an APEX Molecular Line Survey of Bright Debris Disks

    Science.gov (United States)

    Moór, A.; Henning, Th.; Juhász, A.; Ábrahám, P.; Balog, Z.; Kóspál, Á.; Pascucci, I.; Szabó, Gy. M.; Vavrek, R.; Curé, M.; Csengeri, T.; Grady, C.; Güsten, R.; Kiss, Cs.

    2015-11-01

    Debris disks are considered to be gas-poor, but recent observations revealed molecular or atomic gas in several 10-40 Myr old systems. We used the APEX and IRAM 30 m radio telescopes to search for CO gas in 20 bright debris disks. In one case, around the 16 Myr old A-type star HD 131835, we discovered a new gas-bearing debris disk, where the CO 3-2 transition was successfully detected. No other individual system exhibited a measurable CO signal. Our Herschel Space Observatory far-infrared images of HD 131835 marginally resolved the disk at both 70 and 100 μm, with a characteristic radius of ˜170 AU. While in stellar properties HD 131835 resembles β Pic, its dust disk properties are similar to those of the most massive young debris disks. With the detection of gas in HD 131835 the number of known debris disks with CO content has increased to four, all of them encircling young (≤40 Myr) A-type stars. Based on statistics within 125 pc, we suggest that the presence of a detectable amount of gas in the most massive debris disks around young A-type stars is a common phenomenon. Our current data cannot conclude on the origin of gas in HD 131835. If the gas is secondary, arising from the disruption of planetesimals, then HD 131835 is a comparably young, and in terms of its disk, more massive analog of the β Pic system. However, it is also possible that this system, similar to HD 21997, possesses a hybrid disk, where the gas material is predominantly primordial, while the dust grains are mostly derived from planetesimals.

  6. DISCOVERY OF MOLECULAR GAS AROUND HD 131835 IN AN APEX MOLECULAR LINE SURVEY OF BRIGHT DEBRIS DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Moór, A.; Ábrahám, P.; Kóspál, Á.; Szabó, Gy. M.; Kiss, Cs. [Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, P.O. Box 67, H-1525 Budapest (Hungary); Henning, Th.; Balog, Z. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Juhász, A. [Institute of Astronomy, Madingley Road, Cambridge CB3, OHA (United Kingdom); Pascucci, I. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Vavrek, R. [Herschel Science Centre, ESA/ESAC, P.O. Box 78, Villanueva de la Cañada, E-28691, Madrid (Spain); Curé, M. [Instituto de Física y Astronomía, Universidad de Valparaíso (Chile); Csengeri, T.; Güsten, R. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Grady, C., E-mail: moor@konkoly.hu [NASA Goddard Space Flight Center, Code 667, Greenbelt, MD 20771 (United States)

    2015-11-20

    Debris disks are considered to be gas-poor, but recent observations revealed molecular or atomic gas in several 10–40 Myr old systems. We used the APEX and IRAM 30 m radio telescopes to search for CO gas in 20 bright debris disks. In one case, around the 16 Myr old A-type star HD 131835, we discovered a new gas-bearing debris disk, where the CO 3–2 transition was successfully detected. No other individual system exhibited a measurable CO signal. Our Herschel Space Observatory far-infrared images of HD 131835 marginally resolved the disk at both 70 and 100 μm, with a characteristic radius of ∼170 AU. While in stellar properties HD 131835 resembles β Pic, its dust disk properties are similar to those of the most massive young debris disks. With the detection of gas in HD 131835 the number of known debris disks with CO content has increased to four, all of them encircling young (≤40 Myr) A-type stars. Based on statistics within 125 pc, we suggest that the presence of a detectable amount of gas in the most massive debris disks around young A-type stars is a common phenomenon. Our current data cannot conclude on the origin of gas in HD 131835. If the gas is secondary, arising from the disruption of planetesimals, then HD 131835 is a comparably young, and in terms of its disk, more massive analog of the β Pic system. However, it is also possible that this system, similar to HD 21997, possesses a hybrid disk, where the gas material is predominantly primordial, while the dust grains are mostly derived from planetesimals.

  7. Surface Plasmon-Assisted Excitation of Atomic Visible Light Spectral Lines in the Impact of Highly Charged Ions 126Xeq+ on Solid Surfaces

    Institute of Scientific and Technical Information of China (English)

    张小安; 赵永涛; 李福利; 杨治虎; 肖国青; 詹文龙

    2003-01-01

    We measured the visible light spectral lines of sputtering atoms from solid surfaces of Al, Ti, Ni, Ta and Au which are impacted by 150keV126Xeq+ (6≤q≤30). It is found that intensities of the light spectral lines are greatly and suddenly enhanced when the charge state of the ion is raised up to a critical value. If assuming that potential energy released from the incidention due to capturing one electron is enough to excite a surface plasmon, we can estimate the critical charge states and obtain the results very well consistent with the measurements for the above-mentioned target materials. This means that a surface plasmon induced by one electron capture can enhance the excitation of atomic visible light spectral lines in the impact of a highly charged ion on a solid surface.

  8. Discovery of molecular gas around HD 131835 in an APEX molecular line survey of bright debris disks

    CERN Document Server

    Moór, A; Juhász, A; Ábrahám, P; Balog, Z; Kóspál, Á; Pascucci, I; Szabó, Gy M; Vavrek, R; Curé, M; Csengeri, T; Grady, C; Güsten, R; Kiss, Cs

    2015-01-01

    Debris disks are considered to be gas-poor, but recent observations revealed molecular or atomic gas in several 10-40 Myr old systems. We used the APEX and IRAM 30m radiotelescopes to search for CO gas in 20 bright debris disks. In one case, around the 16 Myr old A-type star HD 131835, we discovered a new gas-bearing debris disk, where the CO 3-2 transition was successfully detected. No other individual system exhibited a measurable CO signal. Our Herschel Space Observatory far-infrared images of HD 131835 marginally resolved the disk both at 70 and 100$\\mu$m, with a characteristic radius of ~170 au. While in stellar properties HD 131835 resembles $\\beta$ Pic, its dust disk properties are similar to those of the most massive young debris disks. With the detection of gas in HD 131835 the number of known debris disks with CO content has increased to four, all of them encircling young ($\\leq$40 Myr) A-type stars. Based on statistics within 125 pc, we suggest that the presence of detectable amount of gas in the m...

  9. Literature Review: Theory and Application of In-Line Inspection Technologies for Oil and Gas Pipeline Girth Weld Defection

    Directory of Open Access Journals (Sweden)

    Qingshan Feng

    2016-12-01

    Full Text Available Girth weld cracking is one of the main failure modes in oil and gas pipelines; girth weld cracking inspection has great economic and social significance for the intrinsic safety of pipelines. This paper introduces the typical girth weld defects of oil and gas pipelines and the common nondestructive testing methods, and systematically generalizes the progress in the studies on technical principles, signal analysis, defect sizing method and inspection reliability, etc., of magnetic flux leakage (MFL inspection, liquid ultrasonic inspection, electromagnetic acoustic transducer (EMAT inspection and remote field eddy current (RFDC inspection for oil and gas pipeline girth weld defects. Additionally, it introduces the new technologies for composite ultrasonic, laser ultrasonic, and magnetostriction inspection, and provides reference for development and application of oil and gas pipeline girth weld defect in-line inspection technology.

  10. Total on-line monitoring system of Tokyo gas transmission pipelines; Systeme global de controle et de surveillance des canalisations de transport du gaz developpe par Tokyo gas

    Energy Technology Data Exchange (ETDEWEB)

    Shibata, M. [Tokyo Gas Co., Ltd (Japan)

    2000-07-01

    As Tokyo Gas transmission pipeline is located in residential areas of Metropolitan Tokyo, more precise and advanced maintenance and inspection methods become necessary. A more efficient maintenance and inspection management system is being sought in line with the extension of gas transmission pipelines. Research and development is underway for various types of maintenance /monitoring systems that predict or detect pipeline damage or failure. Some systems have already been put to practical use. Tokyo Gas has developed a total online monitoring system featuring upgraded performance and centralized data processing. This system carries out 24-hour monitoring for damage and failure, and sends warnings to operators at the Pipeline Regional Network Office. This paper introduces the functions of the system, as well as the functions which are currently in the R and D stage. (author)

  11. Weak-light rogue waves, breathers, and their active control in a cold atomic gas via electromagnetically induced transparency

    Science.gov (United States)

    Liu, Junyang; Hang, Chao; Huang, Guoxiang

    2016-06-01

    We propose a scheme to demonstrate the existence of optical Peregrine rogue waves and Akhmediev and Kuznetsov-Ma breathers and realize their active control via electromagnetically induced transparency (EIT). The system we suggest is a cold, Λ -type three-level atomic gas interacting with a probe and a control laser fields and working under EIT condition. We show that, based on EIT with an incoherent optical pumping, which can be used to cancel optical absorption, (1+1)-dimensional optical Peregrine rogue waves, Akhmediev breathers, and Kuznetsov-Ma breathers can be generated with very low light power. In addition, we demonstrate that the Akhmediev and Kuznetsov-Ma breathers in (2+1)-dimensions obtained can be actively manipulated by using an external magnetic field. As a result, these breathers can display trajectory deflections and bypass obstacles during propagation.

  12. Lateral gas phase diffusion length of boron atoms over Si/B surfaces during CVD of pure boron layers

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, V., E-mail: V.Mohammadi@tudelft.nl; Nihtianov, S. [Department of Microelectronics, Delft University of Technology, Mekelweg 4, 2628 CD, Delft (Netherlands)

    2016-02-15

    The lateral gas phase diffusion length of boron atoms, L{sub B}, along silicon and boron surfaces during chemical vapor deposition (CVD) using diborane (B{sub 2}H{sub 6}) is reported. The value of L{sub B} is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and confirmed analytically in the boron deposition temperature range from 700 °C down to 400 °C. For this temperature range the local loading effect of the boron deposition is investigated on the micro scale. A L{sub B} = 2.2 mm was determined for boron deposition at 700 °C, while a L{sub B} of less than 1 mm was observed at temperatures lower than 500 °C.

  13. Inter-laboratory calibration of natural gas round robins for δ2H and δ13C using off-line and on-line techniques

    Science.gov (United States)

    Dai, Jinxing; Xia, Xinyu; Li, Zhisheng; Coleman, Dennis D.; Dias, Robert F.; Gao, Ling; Li, Jian; Deev, Andrei; Li, Jin; Dessort, Daniel; Duclerc, Dominique; Li, Liwu; Liu, Jinzhong; Schloemer, Stefan; Zhang, Wenlong; Ni, Yunyan; Hu, Guoyi; Wang, Xiaobo; Tang, Yongchun

    2012-01-01

    Compound-specific carbon and hydrogen isotopic compositions of three natural gas round robins were calibrated by ten laboratories carrying out more than 800 measurements including both on-line and off-line methods. Two-point calibrations were performed with international measurement standards for hydrogen isotope ratios (VSMOW and SLAP) and carbon isotope ratios (NBS 19 and L-SVEC CO2). The consensus δ13C values and uncertainties were derived from the Maximum Likelihood Estimation (MLE) based on off-line measurements; the consensus δ2H values and uncertainties were derived from MLE of both off-line and on-line measurements, taking the bias of on-line measurements into account. The calibrated consensus values in ‰ relative to VSMOW and VPDB are: NG1 (coal-related gas): Methane: δ2HVSMOW = − 185.1‰ ± 1.2‰, δ13CVPDB = − 34.18‰ ± 0.10‰ Ethane: δ2HVSMOW = − 156.3‰ ± 1.8‰, δ13CVPDB = − 24.66‰ ± 0.11‰ Propane: δ2HVSMOW = − 143.6‰ ± 3.3‰, δ13CVPDB = − 22.21‰ ± 0.11‰ i-Butane: δ13CVPDB = − 21.62‰ ± 0.12‰ n-Butane: δ13CVPDB = − 21.74‰ ± 0.13‰ CO2: δ13CVPDB = − 5.00‰ ± 0.12‰ NG2 (biogas): Methane: δ2HVSMOW = − 237.0‰ ± 1.2‰, δ13CVPDB = − 68.89‰ ± 0.12‰ NG3 (oil-related gas): Methane: δ2HVSMOW = − 167.6‰ ± 1.0‰, δ13CVPDB = − 43.61‰ ± 0.09‰ Ethane: δ2HVSMOW = − 164.1‰ ± 2.4‰, δ13CVPDB = − 40.24‰ ± 0.10‰ Propane: δ2HVSMOW = − 138.4‰ ± 3.0‰, δ13CVPDB = − 33.79‰ ± 0.09‰ All of the assigned values are traceable to the international carbon isotope standard of VPDB and hydrogen isotope standard of VSMOW.

  14. High sensitive formaldehyde graphene gas sensor modified by atomic layer deposition zinc oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Mu, Haichuan; Zhang, Zhiqiang; Wang, Keke; Xie, Haifen, E-mail: hfxie@ecust.edu.cn [Department of Physics, School of Science, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China); Zhao, Xiaojing; Liu, Feng [Department of Physics, Shanghai Normal University, 100 Guilin Road, Shanghai 200234 (China)

    2014-07-21

    Zinc oxide (ZnO) thin films with various thicknesses were fabricated by Atomic Layer Deposition on Chemical Vapor Deposition grown graphene films and their response to formaldehyde has been investigated. It was found that 0.5 nm ZnO films modified graphene sensors showed high response to formaldehyde with the resistance change up to 52% at the concentration of 9 parts-per-million (ppm) at room temperature. Meanwhile, the detection limit could reach 180 parts-per-billion (ppb) and fast response of 36 s was also obtained. The high sensitivity could be attributed to the combining effect from the highly reactive, top mounted ZnO thin films, and high conductive graphene base network. The dependence of ZnO films surface morphology and its sensitivity on the ZnO films thickness was also investigated.

  15. Line shapes and time dynamics of the Förster resonances between two Rydberg atoms in a time-varying electric field

    KAUST Repository

    Yakshina, E. A.

    2016-10-21

    The observation of the Stark-tuned Förster resonances between Rydberg atoms excited by narrowband cw laser radiation requires usage of a Stark-switching technique in order to excite the atoms first in a fixed electric field and then to induce the interactions in a varied electric field, which is scanned across the Förster resonance. In our experiments with a few cold Rb Rydberg atoms, we have found that the transients at the edges of the electric pulses strongly affect the line shapes of the Förster resonances, since the population transfer at the resonances occurs on a time scale of ∼100 ns, which is comparable with the duration of the transients. For example, a short-term ringing at a certain frequency causes additional radio-frequency-assisted Förster resonances, while nonsharp edges lead to asymmetry. The intentional application of the radio-frequency field induces transitions between collective states, whose line shape depends on the interaction strengths and time. Spatial averaging over the atom positions in a single interaction volume yields a cusped line shape of the Förster resonance. We present a detailed experimental and theoretical analysis of the line shape and time dynamics of the Stark-tuned Förster resonances Rb(nP3/2)+Rb(nP3/2)→Rb(nS1/2)+Rb([n+1]S1/2) for two Rb Rydberg atoms interacting in a time-varying electric field.

  16. Laser cooling of dense atomic gases by collisional redistribution of radiation and spectroscopy of molecular dimers in a dense buffer gas environment

    CERN Document Server

    Saß, Anne; Christopoulos, Stavros; Knicker, Katharina; Moroshkin, Peter; Weitz, Martin

    2014-01-01

    We study laser cooling of atomic gases by collisional redistribution of fluorescence. In a high pressure buffer gas regime, frequent collisions perturb the energy levels of alkali atoms, which allows for the absorption of a far red detuned irradiated laser beam. Subsequent spontaneous decay occurs close to the unperturbed resonance frequency, leading to a cooling of the dense gas mixture by redistribution of fluorescence. Thermal deflection spectroscopy indicates large relative temperature changes down to and even below room temperature starting from an initial cell temperature near 700 K. We are currently performing a detailed analysis of the temperature distribution in the cell. As we expect this cooling technique to work also for molecular-noble gas mixtures, we also present initial spectroscopic experiments on alkali-dimers in a dense buffer gas surrounding.

  17. Atlas cell testing for selection of tank linings in oil and gas production vessels and tanks

    Energy Technology Data Exchange (ETDEWEB)

    Gray, L.G.S.; DeVarennes, N. [KTA-Tator Canada Inc., Edmonton, AB (Canada); Bloor, B. [EnCana Resources, Weyburn, SK (Canada); O' Donoghue, M.; Graham, R.; Garrett, R.; Datta, V. [Devoe Coatings, Edmonton, AB (Canada); Franke, B. [International Polymer Canada Inc., Edmonton, AB (Canada)

    2008-07-01

    Atlas cell and autoclave laboratory tests are used to select internal linings for vessels and tanks used in oil and gas production processes. However, results from the tests often correlate poorly with field performance. This paper investigated operational details of the tests and evaluated their influence on the cold wall effects created in the Atlas cells. The aim of the study was to gain an improved understanding of the Atlas cell test and determine the reasons behind discrepancies in field tests. A modified Atlas cell design was developed to test 8 coated test panels. The Atlas cell consisted of a 25 litre, 8-sided stainless steel tank. Thermocouples were placed near the coated surfaces of each panel. Water from temperature-controlled water baths was circulated independently through cooling jackets. Various polymer-based coatings were used in the tests. The performance of the coatings was evaluated using visual inspection; adhesion; and coating impedance tests. Results were then used to explain the contradictory behaviour of coatings in the Atlas and autoclave tests and field performance. The experiments showed that steel thickness had no significant effects on Atlas cell results. Coatings with high cold-wall resistance had low impedance. The ability of water to move freely within the coating reduced its tendency to become trapped at the coating and steel interface. A good correlation between Atlas cell test results and coating field performance was found when large temperature gradients were produced by steel structural design and where coating performance was related to elevated coating permeability. It was concluded that Atlas tests are only valid when a similar substantial cold wall effect is occurring. 11 refs., 11 tabs., 7 figs.

  18. Gas atomization processing of tin and silicon modified LaNi5 for nickel-metal hydride battery applications

    Energy Technology Data Exchange (ETDEWEB)

    Ting, Jason [Iowa State Univ., Ames, IA (United States)

    1999-02-12

    Numerous researchers have studied the relevant material properties of so-called AB5 alloys for battery applications. These studies involved LaNi5 substituted alloys which were prepared using conventional cast and crush alloying techniques. While valuable to the understanding of metal hydride effects, the previous work nearly ignored the potential for alternative direct powder production methods, like high pressure gas atomization (HPGA). Thus, there is a need to understand the relationship between gas atomization processes, powder particle solidification phases, and hydrogen absorption properties of ultra fine (< 25 μm) atomized powders with high surface area for enhanced battery performance. Concurrently, development of a gas atomization nozzle that is more efficient than all current designs is needed to increase the yield of ultrafine AB5 alloy powder for further processing advantage. Gas atomization processing of the AB5 alloys was demonstrated to be effective in producing ultrafine spherical powders that were resilient to hydrogen cycling for the benefit of improving corrosion resistance in battery application. These ultrafine powders benefited from the rapid solidification process by having refined solute segregation in the microstructure of the gas atomized powders which enabled a rapid anneal treatment of the powders. The author has demonstrated the ability to produce high yields of ultrafine powder efficiently and cost effectively, using the new HPGA-III technology. Thus, the potential benefits of processing AB5 alloys using the new HPGA technology could reduce manufacturing cost of nickel-metal hydride powder. In the near future, the manufacture of AB5 alloy powders could become a continuous and rapid production process. The economic benefit of an improved AB5 production process may thereby encourage the use of nickel-metal hydride rechargeable batteries in electrical vehicle

  19. 18 CFR 12.43 - Power and communication lines and gas pipelines.

    Science.gov (United States)

    2010-04-01

    ... between any power or communication line constructed after March 1, 1981 and any vessels using project... Safety Code in effect at the time the power or communication line is constructed. (c) The Regional Engineer may require a licensee or applicant to provide signs at or near power or communication lines...

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

    Science.gov (United States)

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

    2008-02-07

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

  1. Kinetic study of the reaction of chlorine atoms with hydroxyacetone in gas-phase

    Science.gov (United States)

    Stoeffler, Clara; Joly, Lilian; Durry, Georges; Cousin, Julien; Dumelié, Nicolas; Bruyant, Aurélien; Roth, Estelle; Chakir, Abdelkhaleq

    2013-12-01

    In this letter the kinetics of the reaction of hydroxyacetone CH3C(O)CH2OH with Cl atoms is investigated using the relative rate technique. Experiments are carried out in a 65 L multipass photoreactor in the temperature range of 281-350 K. A mid-infrared spectrometer based on a quantum cascade laser in external cavity emitting at 9.5 μm is used to analyze the reactants. The determined rate coefficient for the investigated reaction is (1.7 ± 0.3) × 10-11exp(381.5 ± 57.3/T). The results are presented and discussed in terms of precision and compared with those obtained previously. The impact of Cl atoms on the atmospheric life time of hydroxyacetone is also discussed. Developing analytical techniques to quantify this compound in the atmosphere. Several methods of measurement have been used including the technique of proton transfer mass spectrometry (PTR-MS) [2] and derivatization with a chemical agent such as dinitrophenylhydrazine (DNPH) [3,4] followed by GC/MS or HPLC analyses. The HA amount in the troposphere was found to be in the order of a few hundred parts per trillion by volume [4], Performing laboratory experiments in order to study the HA reactivity with atmospheric oxidants. The first study on the kinetic of the reaction between OH radicals and HA was made by Dagault et al. [5] whose work was performed at room temperature by flash photolysis-resonance fluorescence. The determined rate constant implies a lifetime of a few days for HA relative to oxidation by OH radicals. Orlando et al. performed mechanistic and kinetics studies of the reaction of HA with OH radicals and Cl atoms at room temperature using a relative method [6]. Products detection was performed using FTIR spectroscopy. Moreover, these authors studied the photolysis of HA to determine its quantum yield and UV absorption spectrum. These studies showed that HA is principally removed from the atmosphere by reaction with OH radicals. Kinetic studies of the reaction of OH radicals with HA as a

  2. Alkali metal and simple gas atom adsorption and coadsorption on transition metal surfaces

    CERN Document Server

    Norris, A G

    2000-01-01

    system is formed by adsorption of potassium or cesium on the Ni(100)c(2x2)-O overlayer. The difficulty of the structural fit is compounded' by the size of the unit cell. In this study, Anomalous Scattering was used to investigate whether there is a contribution from the nickel substrate to the reconstruction. Measurements of the fractional order rods at 10 eV and 200 eV below the nickel K edge (8333 eV) showed no discernible differences and involvement of the nickel substrate in the reconstruction can be eliminated. Alkali metal coadsorption systems represent a step along the pathway from simple model adsorbate overlayers to more technologically relevant real systems. Such is their complexity, however, that very few systems have been solved structurally. Presented here are SXRD and STM investigations of two such systems. The first study involves potassium adsorption on the Ni(100)(2x2)p4g-N surface, where a clock reconstruction is present with the nickel substrate atoms rotated in alternate clockwise and anti...

  3. Cosmological evolution of atomic gas and implications for 21 cm HI absorption

    CERN Document Server

    Braun, Robert

    2012-01-01

    Galaxy disks are shown to contain a significant population of atomic clouds of 100pc linear size which are self-opaque in the 21cm transition. These objects have HI column densities as high as 10^23 and contribute to a global opacity correction factor of 1.34+/-0.05 that applies to the integrated 21cm emission to obtain a total HI mass estimate. Opacity-corrected images of the nearest external galaxies have been used to form a robust z=0 distribution function of HI, f(N_HI,X,z=0), the probability of encountering a specific HI column density per unit comoving distance. This is contrasted with previously published determinations of f(N_HI,X) at z=1 and 3. A systematic decline of moderate column density (1820.3) has also declined systematically over this redshift interval by a similar amount, while the cosmological mass density in such systems has declined by only a factor of two to its current, opacity corrected value of Omega_HI^DLA(z=0) = 5.4 +/- 0.9x10^-4. We utilize the tight, but strongly non-linear depend...

  4. Indirect Estimates of the Total Gas Content of SDSS-IV/MaNGA Galaxies from Optical Emission Lines

    Science.gov (United States)

    Tremonti, Christina A.; Pace, Zachary; Andrews, Brett; Law, David R.; Li, Cheng; Martinsson, Thomas; Masters, Karen; Stark, David; Sanchez, Sebastian; Storchi-Bergmann, Thaisa; MaNGA Team

    2016-01-01

    To understand galaxy evolution it is critical to obtain a census of both the stellar and gaseous contents of galaxies. The SDSS-IV MaNGA survey will deliver exquisite stellar mass maps of ~10,000 nearby galaxies. However, radio surveys capable of providing matched resolution gas data for a large fraction of the MaNGA sample are a decade or more away. We are therefore exploring a new technique for obtaining maps of the total gas content directly from the MaNGA data. Following the method outlined in Brinchmann et al. 2013, we use the dust optical depth and the nebular metallicity measured from optical emission lines to estimate the total gas surface density in individual spaxels. We combine this with estimates of the stellar mass in each spaxel to produce spatially resolved estimates of the gas mass fraction. We compare trends in the global gas mass fraction with stellar mass and NUV-r color to those found in the literature. We explore how the radial gas mass fraction gradients of MaNGA galaxies correlate with other properties such as total stellar mass, specific star formation rate (SFR/M*), concentration, and environment.

  5. Utilization of on-line corrosion monitoring in the flue gas cleaning system

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Nielsen, Lars V.; Petersen, Michael B.

    2015-01-01

    The power plant unit 1 at Amager, Denmark is a 350 MWth multifuel suspension-fired plant commissioned in 2009 which uses biomass. Increasing corrosion problems in the flue gas cleaning system have been observed since 2011 in both the gas-gas preheater and the booster fan and booster fan duct...... fan. The corrosion rates measured with respect to time were correlated to plant data such as load, temperature, gas composition, water content as well as change in the fuel used. From these results it is clear that many shutdowns/start-ups influence corrosion and therefore cause decreased lifetime...

  6. Atomic physics

    CERN Document Server

    Born, Max

    1989-01-01

    The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.

  7. Qualitative tissue differentiation by analysing the intensity ratios of atomic emission lines using laser induced breakdown spectroscopy (LIBS): prospects for a feedback mechanism for surgical laser systems.

    Science.gov (United States)

    Kanawade, Rajesh; Mahari, Fanuel; Klämpfl, Florian; Rohde, Maximilian; Knipfer, Christian; Tangermann-Gerk, Katja; Adler, Werner; Schmidt, Michael; Stelzle, Florian

    2015-01-01

    The research work presented in this paper focuses on qualitative tissue differentiation by monitoring the intensity ratios of atomic emissions using 'Laser Induced Breakdown Spectroscopy' (LIBS) on the plasma plume created during laser tissue ablation. The background of this study is to establish a real time feedback control mechanism for clinical laser surgery systems during the laser ablation process. Ex-vivo domestic pig tissue samples (muscle, fat, nerve and skin) were used in this experiment. Atomic emission intensity ratios were analyzed to find a characteristic spectral line for each tissue. The results showed characteristic elemental emission intensity ratios for the respective tissues. The spectral lines and intensity ratios of these specific elements varied among the different tissue types. The main goal of this study is to qualitatively and precisely identify different tissue types for tissue specific laser surgery.

  8. Gold volatile species atomization and preconcentration in quartz devices for atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Arslan, Yasin [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Mehmet Akif Ersoy University, Faculty of Arts & Sciences, Chemistry Department, 15030 Burdur (Turkey); Musil, Stanislav; Matoušek, Tomáš; Kratzer, Jan [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Dědina, Jiří, E-mail: dedina@biomed.cas.cz [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic)

    2015-01-01

    The on-line atomization of gold volatile species was studied and the results were compared with thermodynamic calculations in several quartz atomizers, namely: diffusion flame, flame-in-gas-shield, flame-in-plain-tube, externally heated T-tube and externally heated flame-in-T-tube. Atomization mechanism in the explored devices is proposed, where volatile species are converted to thermodynamically stable AuH at elevated temperature over 500 °C and then atomized by an interaction with a cloud of hydrogen radicals. Because of its inherent simplicity and robustness, diffusion flame was employed as a reference atomizer. It yielded atomization efficiency of 70 to 100% and a very good long time reproducibility of peak area sensitivity: 1.6 to 1.8 s μg{sup −1}. Six and eleven times higher sensitivity, respectively, was provided by atomizers with longer light paths in the observation volume, i.e. externally heated T-tube and externally heated flame-in-T-tube. The latter one, offering limit of detection below 0.01 μg ml{sup −1}, appeared as the most prospective for on-line atomization. Insight into the mechanism of atomization of gold volatile species, into the fate of free atoms and into subsequent analyte transfer allowed to assess possibilities of in-atomizer preconcentration of gold volatile species: it is unfeasible with quartz atomizers but a sapphire tube atomizer could be useful in this respect. - Highlights: • On-line atomization of gold volatile species for AAS in quartz devices was studied. • Atomization mechanism was proposed and atomization efficiency was estimated. • Possibilities of in-atomizer preconcentration of gold volatile species were assessed.

  9. Comment on "Optical Response of Gas-Phase Atoms at Less than lambda/80 from a Dielectric Surface" published by K. A. Whittaker et al.

    CERN Document Server

    Bloch, Daniel

    2015-01-01

    Comment on "Optical Response of Gas-Phase Atoms at Less than lambda/80 from a Dielectric Surface" published by K. A. Whittaker, J. Keaveney, I. G. Hughes, A. Sargsyan, D. Sarkisyan, C. S. Adams in Phys. Rev. Lett. Lett 112 253201 (2014)

  10. Spectral aspects of the determination of Si in organic and aqueous solutions using high-resolution continuum source or line source flame atomic absorption spectrometry

    Science.gov (United States)

    Kowalewska, Zofia; Pilarczyk, Janusz; Gościniak, Łukasz

    2016-06-01

    High-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) was applied to reveal and investigate spectral interference in the determination of Si. An intensive structured background was observed in the analysis of both aqueous and xylene solutions containing S compounds. This background was attributed to absorption by the CS molecule formed in the N2O-C2H2 flame. The lines of the CS spectrum at least partially overlap all five of the most sensitive Si lines investigated. The 251.611 nm Si line was demonstrated to be the most advantageous. The intensity of the structured background caused by the CS molecule significantly depends on the chemical form of S in the solution and is the highest for the most-volatile CS2. The presence of O atoms in an initial S molecule can diminish the formation of CS. To overcome this S effect, various modes of baseline fitting and background correction were evaluated, including iterative background correction (IBC) and utilization of correction pixels (WRC). These modes were used either independently or in conjunction with least squares background correction (LSBC). The IBC + LSBC mode can correct the extremely strong interference caused by CS2 at an S concentration of 5% w:w in the investigated solution. However, the efficiency of this mode depends on the similarity of the processed spectra and the correction spectra in terms of intensity and in additional effects, such as a sloping baseline. In the vicinity of the Si line, three lines of V were recorded. These lines are well-separated in the HR-CS FAAS spectrum, but they could be a potential source of overcorrection when using line source flame atomic absorption spectrometry (LS FAAS). The expected signal for the 251.625 nm Fe line was not registered at 200 mg L- 1 Fe concentration in the solution, probably due to the diminished population of Fe atoms in the high-temperature flame used. The observations made using HR-CS FAAS helped to establish a "safe" level

  11. Line shapes and time dynamics of the F\\"orster resonances between two Rydberg atoms in a time-varying electric field

    CERN Document Server

    Yakshina, E A; Beterov, I I; Entin, V M; Andreeva, C; Cinins, A; Markovski, A; Iftikhar, Z; Ekers, A; Ryabtsev, I I

    2016-01-01

    The observation of the Stark-tuned F\\"orster resonances between Rydberg atoms excited by narrowband cw laser radiation requires usage of a Stark-switching technique in order to excite the atoms first in a fixed electric field and then to induce the interactions in a varied electric field, which is scanned across the F\\"orster resonance. In our experiments with a few cold Rb Rydberg atoms we have found that the transients at the edges of the electric pulses strongly affect the line shapes of the F\\"orster resonances, since the resonances occur mainly on a time scale of ~100 ns, which is comparable with the duration of the transients. For example, a short-term ringing at a certain frequency causes additional radio-frequency-assisted F\\"orster resonances, while non-sharp edges lead to asymmetry. The intentional application of the radio-frequency field induces transitions between collective states, whose line shape depends on the interaction strengths and time. Spatial averaging over the atom positions in a singl...

  12. On-line measurement of raw gas elemental composition in fluidized bed biomass steam gasification

    Energy Technology Data Exchange (ETDEWEB)

    Neves, D. [Dept. of Environment and Planning, Centre of Environmental and Marine Studies, Univ. of Aveiro, Campus Universitario de Santiago, Aveiro (Portugal); Dept. of Energy and Environment, Chalmers Univ. of Technology, Goeteborg (Sweden); Thunman, H.; Larsson, A.; Seemann, M. [Dept. of Energy and Environment, Chalmers Univ. of Technology, Goeteborg (Sweden); Tarelho, L.; Matos, A. [Dept. of Environment and Planning, Centre of Environmental and Marine Studies, Univ. of Aveiro, Campus Universitario de Santiago, Aveiro (Portugal)

    2012-11-01

    At the present stage of technology development pursuing to achieve unattended gasification processes, the available methods to determine the CHON composition of raw gas involve a great deal of laboratory tasks, making it unpractical, time-consuming and costly. For instance, there are available analyzers to measure the chemical composition of dry raw gas but offline methods are used to determine the liquids (organic compounds + water). An alternative that is investigated in this work is to convert the raw gas first into simple product species that are easily analyzed. The straightforward way to achieve this is to burn the gas with proper amount of oxygen to assure quantitative conversion into CO{sub 2}, H{sub 2}O and N{sub 2}. This method is demonstrated here by monitoring the CHON composition of raw gas with high temporal resolution from Chalmers 2MW{sub th} FB gasifier.

  13. The clustering of galaxies as a function of their photometrically-estimated atomic gas content

    CERN Document Server

    Li, Cheng; Fu, Jian; Wang, Jing; Catinella, Barbara; Fabello, Silvia; Schiminovich, David; Zhang, Wei

    2012-01-01

    We introduce a new photometric estimator of the HI mass fraction (M_HI/M_*) in local galaxies, which is a linear combination of four parameters: stellar mass, stellar surface mass density, NUV-r colour, and g-i colour gradient. It is calibrated using samples of nearby galaxies (0.025line detections from the GASS and ALFALFA surveys, and it is demonstrated to provide unbiased M_HI/M_* estimates even for HI-rich galaxies. We apply this estimator to a sample of ~24,000 galaxies from the SDSS/DR7 in the same redshift range. We then bin these galaxies by stellar mass and HI mass fraction and compute projected two point cross-correlation functions with respect to a reference galaxy sample. Results are compared with predictions from current semi-analytic models of galaxy formation. The agreement is good for galaxies with stellar masses larger than 10^10 M_sun, but not for lower mass systems. We then extend the analysis by studying the bias of HI-poor or HI-rich galaxies with respect to galaxie...

  14. The origin of gas in the Extended Narrow Line Region of nearby Seyfert galaxies.I. NGC 7212

    CERN Document Server

    Cracco, V; Di Mille, F; Vaona, L; Frassati, A; Smirnova, A A; La Mura, G; Moiseev, A V; Rafanelli, P

    2011-01-01

    The Extended Narrow Line Region (ENLR) of Active Galactic Nuclei (AGN) is a region of highly ionized gas with a size of few up to 15-20 kpc. When it shows a conical or bi-conical shape with the apexes pointing towards the active nucleus, this region is also called ionization cones. The ionization cones are an evidence of the Unified Model that predicts an anisotropic escape of ionizing photons from the nucleus confined to a cone by a dusty torus. Many details about the complex structure of the ENLR still remain unveiled, as for example the origin of the ionized gas. Here we present new results of a study of the physical and kinematical properties of the circumnuclear gas in the nearby Seyfert 2 galaxy NGC 7212. Medium and high resolution integral field spectra and broad-band photometric data were collected and analysed in the frame of an observational campaign of nearby Seyfert galaxies, aiming to handle the complicated issue of the origin of the gas in the ENLR. This work is based on: (i) analysis of gas phy...

  15. Redeposition in plasma-assisted atomic layer deposition: Silicon nitride film quality ruled by the gas residence time

    Energy Technology Data Exchange (ETDEWEB)

    Knoops, Harm C. M., E-mail: h.c.m.knoops@tue.nl, E-mail: w.m.m.kessels@tue.nl [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Oxford Instruments Plasma Technology, North End, Bristol BS49 4AP (United Kingdom); Peuter, K. de; Kessels, W. M. M., E-mail: h.c.m.knoops@tue.nl, E-mail: w.m.m.kessels@tue.nl [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2015-07-06

    The requirements on the material properties and growth control of silicon nitride (SiN{sub x}) spacer films in transistors are becoming ever more stringent as scaling of transistor structures continues. One method to deposit high-quality films with excellent control is atomic layer deposition (ALD). However, depositing SiN{sub x} by ALD has turned out to be very challenging. In this work, it is shown that the plasma gas residence time τ is a key parameter for the deposition of SiN{sub x} by plasma-assisted ALD and that this parameter can be linked to a so-called “redeposition effect”. This previously ignored effect, which takes place during the plasma step, is the dissociation of reaction products in the plasma and the subsequent redeposition of reaction-product fragments on the surface. For SiN{sub x} ALD using SiH{sub 2}(NH{sup t}Bu){sub 2} as precursor and N{sub 2} plasma as reactant, the gas residence time τ was found to determine both SiN{sub x} film quality and the resulting growth per cycle. It is shown that redeposition can be minimized by using a short residence time resulting in high-quality films with a high wet-etch resistance (i.e., a wet-etch rate of 0.5 nm/min in buffered HF solution). Due to the fundamental nature of the redeposition effect, it is expected to play a role in many more plasma-assisted ALD processes.

  16. Reactions of hot deuterium atoms with OCS in the gas phase and in OCS--DI complexes

    Energy Technology Data Exchange (ETDEWEB)

    Boehmer, E.; Mikhaylichenko, K.; Wittig, C. (University of Southern California, Department of Chemistry, Los Angeles, California 90089-0482 (United States))

    1993-11-01

    Reactions of photolytically prepared hot deuterium atoms with OCS have been investigated: (i) under gas phase, single collision, arrested relaxation (i.e., bulk) conditions; and (ii) by photoinitiating reactions within weakly bound OCS--DI complexes. Nascent SD([ital X] [sup 2][Pi], [ital v]=0) rotational, spin--orbit, and [Lambda]-doublet populations were obtained for the photolysis wavelengths 250, 225, and 223 nm by using [ital A] [sup 2][Sigma][l arrow][ital X] [sup 2][Pi] laser induced fluorescence (LIF). The reason for using deuterium is strictly experimental: [ital A] [sup 2][Sigma] predissociation rates are considerably smaller for SD than for SH. The SD ([ital v]=0) rotational distribution was found to be very cold and essentially the same for both bulk and complexed conditions; the most probable rotational energy is [similar to]180 cm[sup [minus]1]. No bias in [Lambda]-doublet populations was detected. Spin--orbit excitation for bulk conditions was estimated to be [[sup 2][Pi][sub 1/2

  17. Reactions of hot deuterium atoms with OCS in the gas phase and in OCS-DI complexes

    Science.gov (United States)

    Böhmer, E.; Mikhaylichenko, K.; Wittig, C.

    1993-11-01

    Reactions of photolytically prepared hot deuterium atoms with OCS have been investigated: (i) under gas phase, single collision, arrested relaxation (i.e., bulk) conditions; and (ii) by photoinitiating reactions within weakly bound OCS-DI complexes. Nascent SD(X 2Π, v=0) rotational, spin-orbit, and Λ-doublet populations were obtained for the photolysis wavelengths 250, 225, and 223 nm by using A 2Σ←X 2Π laser induced fluorescence (LIF). The reason for using deuterium is strictly experimental: A 2Σ predissociation rates are considerably smaller for SD than for SH. The SD (v=0) rotational distribution was found to be very cold and essentially the same for both bulk and complexed conditions; the most probable rotational energy is ˜180 cm-1. No bias in Λ-doublet populations was detected. Spin-orbit excitation for bulk conditions was estimated to be [2Π1/2]/[2Π3/2]˜0.25, where 2Π1/2 is the upper spin-orbit component. This ratio could not be obtained with complexes because of limited S/N. The complete set of present and past experimental findings, combined with recent theoretical results of Rice, Cartland, and Chabalowski suggest a mechanism in which SD derives from a very short lived HSCO precursor. This can result from direct hydrogen attack at the sulfur and/or the transfer of hydrogen from carbon to sulfur via the HCOS intermediate.

  18. Fabrication Of Zn4Sb3 Alloys By A Combination Of Gas-Atomization And Spark Plasma Sintering Processes

    Directory of Open Access Journals (Sweden)

    Dharmaiah P.

    2015-06-01

    Full Text Available In this study, single phase polycrystalline Zn4Sb3 as well as 11 at.% Zn-rich Zn4Sb3 alloy having ε-Zn4Sb3 (majority phase and Zn (minority phase phases bulk samples produced by gas-atomization and subsequently consolidated by spark plasma sintering (SPS process. The crystal structures were analyzed by X-ray diffraction (XRD and cross-sectional microstructure were observed by the scanning electron microscopy (SEM. The internal grain microstructure of 11at.% Zn-rich Zn4Sb3 powders shows lamellar structure. Relative density, Vickers hardness and crack lengths were measured to investigate the effect of sintering temperature of Zn4Sb3 samples which are sintered at 653, 673 and 693 K. Relative density of the single phase bulk Zn4Sb3 sample reached to 99.2% of its theoretical density. The micro Vickers hardness of three different sintering temperatures were found around 2.17 – 2.236 GPa.

  19. Two-Dimensional Electron Gas at SrTiO3-Based Oxide Heterostructures via Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Sang Woon Lee

    2016-01-01

    Full Text Available Two-dimensional electron gas (2DEG at an oxide interface has been attracting considerable attention for physics research and nanoelectronic applications. Early studies reported the formation of 2DEG at semiconductor interfaces (e.g., AlGaAs/GaAs heterostructures with interesting electrical properties such as high electron mobility. Besides 2DEG formation at semiconductor junctions, 2DEG was realized at the interface of an oxide heterostructure such as the LaAlO3/SrTiO3 (LAO/STO heterojunction. The origin of 2DEG was attributed to the well-known “polar catastrophe” mechanism in oxide heterostructures, which consist of an epitaxial LAO layer on a single crystalline STO substrate among proposed mechanisms. Recently, it was reported that the creation of 2DEG was achieved using the atomic layer deposition (ALD technique, which opens new functionality of ALD in emerging nanoelectronics. This review is focused on the origin of 2DEG at oxide heterostructures using the ALD process. In particular, it addresses the origin of 2DEG at oxide interfaces based on an alternative mechanism (i.e., oxygen vacancies.

  20. Pressurized liquid extraction followed by gas chromatography with atomic emission detection for the determination of fenbutatin oxide in soil samples.

    Science.gov (United States)

    Canosa, P; Montes, R; Lamas, J P; García-López, M; Orriols, I; Rodríguez, I

    2009-08-15

    A novel method for the determination of the miticide bis[tris(2-methyl-2-phenylpropyl)tin] oxide, also known as fenbutatin oxide (FBTO), in agricultural soils is presented. Pressurized liquid extraction (PLE) followed by analyte derivatization and extraction into isooctane was the used sample preparation approach. Selective determination was achieved by gas chromatography with atomic emission detection (GC-AED). Influence of different parameters on the performance of the extraction process is thoroughly discussed; moreover, some relevant aspects related to derivatization, determination and quantification steps are also presented. As regards PLE, the type of solvent and the temperature were the most relevant variables. Under optimized conditions, acetone, without any acidic modifier, was employed as extractant at 80 degrees C. Cells were pressurized at 1500 psi, and 2 static cycles of 1 min each were applied. Acetone extracts (ca. 25 mL) were concentrated to 1 mL, derivatized with sodium tetraethyl borate (NaBEt(4)) and the FBTO derivative, resulting from cleavage of the Sn-O-Sn bond followed by ethylation of the hydroxyl fragments, extracted into isooctane and determined by GC-AED. Under final working conditions, the proposed method provided recoveries from 76 to 99% for spiked soil samples, a limit of quantification of 2 ng g(-1) and an acceptable precision. Analysis of samples from vineyards sprayed with FBTO, confirmed the persistence of the miticide in soil for more than 1 year after being applied.

  1. ɛ -pseudoclassical model for quantum resonances in a cold dilute atomic gas periodically driven by finite-duration standing-wave laser pulses

    Science.gov (United States)

    Beswick, Benjamin T.; Hughes, Ifan G.; Gardiner, Simon A.; Astier, Hippolyte P. A. G.; Andersen, Mikkel F.; Daszuta, Boris

    2016-12-01

    Atom interferometers are a useful tool for precision measurements of fundamental physical phenomena, ranging from the local gravitational-field strength to the atomic fine-structure constant. In such experiments, it is desirable to implement a high-momentum-transfer "beam splitter," which may be achieved by inducing quantum resonance in a finite-temperature laser-driven atomic gas. We use Monte Carlo simulations to investigate these quantum resonances in the regime where the gas receives laser pulses of finite duration and derive an ɛ -classical model for the dynamics of the gas atoms which is capable of reproducing quantum resonant behavior for both zero-temperature and finite-temperature noninteracting gases. We show that this model agrees well with the fully quantum treatment of the system over a time scale set by the choice of experimental parameters. We also show that this model is capable of correctly treating the time-reversal mechanism necessary for implementing an interferometer with this physical configuration and that it explains an unexpected universality in the dynamics.

  2. Gas exchange, heat production and oxidation of fat in chicken embryos from a fast or slow growing line

    DEFF Research Database (Denmark)

    Chwalibog, André; Tauson, Anne-Helene; Ali, Abdalla;

    2007-01-01

    The experiment comprised 48 chicken (Gallus gallus) embryos from a modern, fast growing line, Ross 308 (RO) and 48 from a slow growing line, Labresse (LA). The O(2) consumption and CO(2) production were measured in an open-air-circuit respiration unit, and heat production (HE) from embryos...... was calculated at an age of 10, 13, 16 and 19 days. Gas exchange was below 10 ml/h for RO and LA by an age of 10-13 days, increasing steeply to a "peak" on day 16 and then slowing down between 16 and 19 days. The pattern of curves for gas exchange was identical for RO and LA, but on a lower level for LA. HE...... followed the pattern of gas exchange, with a mean around 50 J/h on day 10, increasing to 528 (RO) and 402 (LA) J/h on day 19. The main source of HE was oxidized fat. In addition to respiration experiments chemical analyses were carried out on 60 eggs from RO and 60 from LA. Prior to chemical analyses...

  3. Molecular line emission in NGC1068 imaged with ALMA. I An AGN-driven outflow in the dense molecular gas

    CERN Document Server

    Garcia-Burillo, S; Usero, A; Aalto, S; Krips, M; Viti, S; Alonso-Herrero, A; Hunt, L K; Schinnerer, E; Baker, A J; Casasola, F Boone V; Colina, L; Costagliola, F; Eckart, A; Fuente, A; Henkel, C; Labiano, A; Martin, S; Marquez, I; Muller, S; Planesas, P; Almeida, C Ramos; Spaans, M; Tacconi, L J; van der Werf, P P

    2014-01-01

    We investigate the fueling and the feedback of star formation and nuclear activity in NGC1068, a nearby (D=14Mpc) Seyfert 2 barred galaxy, by analyzing the distribution and kinematics of the molecular gas in the disk. We have used ALMA to map the emission of a set of dense molecular gas tracers (CO(3-2), CO(6-5), HCN(4-3), HCO+(4-3) and CS(7-6)) and their underlying continuum emission in the central r ~ 2kpc of NGC1068 with spatial resolutions ~ 0.3"-0.5" (~ 20-35pc). Molecular line and dust continuum emissions are detected from a r ~ 200pc off-centered circumnuclear disk (CND), from the 2.6kpc-diameter bar region, and from the r ~ 1.3kpc starburst (SB) ring. Most of the emission in HCO+, HCN and CS stems from the CND. Molecular line ratios show dramatic order-of-magnitude changes inside the CND that are correlated with the UV/X-ray illumination by the AGN, betraying ongoing feedback. The gas kinematics from r ~ 50pc out to r ~ 400pc reveal a massive (M_mol ~ 2.7 (+0.9, -1.2) x 10^7 Msun) outflow in all molec...

  4. Hubble Space Telescope Faint Object Camera Spectroscopy of the Narrow-Line Region of NGC 4151. I. Gas Kinematics

    CERN Document Server

    Winge, C; Macchetto, F D; Capetti, A; Marconi, A; Winge, Claudia; Axon, David J.

    1999-01-01

    We present the results from a detailed kinematic analysis of both ground-based, and Hubble Space Telescope/Faint Object Camera long-slit spectroscopy at sub-arcsec spatial resolution, of the narrow-line region of NGC 4151. In agreement with previous work, the extended emission gas (R > 4") is found to be in normal rotation in the galactic plane, a behaviour that we were able to trace even across the nuclear region, where the gas is strongly disturbed by the interaction with the radio jet, and connects smoothly with the large scale rotation defined by the neutral gas emission. The HST data, at 0.029" spatial resolution, allow us for the first time to truly isolate the kinematic behaviour of the individual clouds in the inner narrow-line region. We find that, underlying the perturbations introduced by the radio ejecta, the general velocity field can still be well represented by planar rotation down to a radius of ~ 0.5" (30 pc), distance at which the rotation curve has its turnover. The most striking result tha...

  5. Reconstruction of combustion temperature and gas concentration distributions using line-of-sight tunable diode laser absorption spectroscopy

    Science.gov (United States)

    Zhang, Zhirong; Sun, Pengshuai; Pang, Tao; Xia, Hua; Cui, Xiaojuan; Li, Zhe; Han, Luo; Wu, Bian; Wang, Yu; Sigrist, Markus W.; Dong, Fengzhong

    2016-07-01

    Spatial temperature and gas concentration distributions are crucial for combustion studies to characterize the combustion position and to evaluate the combustion regime and the released heat quantity. Optical computer tomography (CT) enables the reconstruction of temperature and gas concentration fields in a flame on the basis of line-of-sight tunable diode laser absorption spectroscopy (LOS-TDLAS). A pair of H2O absorption lines at wavelengths 1395.51 and 1395.69 nm is selected. Temperature and H2O concentration distributions for a flat flame furnace are calculated by superimposing two absorption peaks with a discrete algebraic iterative algorithm and a mathematical fitting algorithm. By comparison, direct absorption spectroscopy measurements agree well with the thermocouple measurements and yield a good correlation. The CT reconstruction data of different air-to-fuel ratio combustion conditions (incomplete combustion and full combustion) and three different types of burners (one, two, and three flat flame furnaces) demonstrate that TDLAS has the potential of short response time and enables real-time temperature and gas concentration distribution measurements for combustion diagnosis.

  6. Influence of inelastic collisions with hydrogen atoms on the formation of AlI and SiI lines in stellar spectra

    Science.gov (United States)

    Mashonkina, L. I.; Belyaev, A. K.; Shi, J.-R.

    2016-06-01

    We have performed calculations by abandoning the assumption of local thermodynamic equilibrium (within the so-called non-LTE approach) for Al I and Si I with model atmospheres corresponding to stars of spectral types F-G-Kwith differentmetal abundances. To take into account inelastic collisions with hydrogen atoms, for the first time we have applied the cross sections calculated by Belyaev et al. using model approaches within the formalism of the Born-Oppenheimer quantum theory. We show that for Al I non-LTE leads to higher ionization (overionization) than in LTE in the spectral line formation region and to a weakening of spectral lines, which is consistent with earlier non-LTE studies. However, our results, especially for the subordinate lines, differ quantitatively from the results of predecessors. Owing to their large cross sections, the ion-pair production and mutual neutralization processes Al I( nl) + HI(1 s) ↔ Al II(3 s 2) + H- provide a close coupling of highly excited Al I levels with the Al II ground state, which causes the deviations from the equilibrium level population to decrease compared to the calculations where the collisions only with electrons are taken into account. For three moderately metal-deficient dwarf stars, the aluminum abundance has been determined from seven Al I lines in different models of their formation. Under the assumption of LTE and in non-LTE calculations including the collisions only with electrons, the Al I 3961 ˚A resonance line gives a systematically lower abundance than the mean abundance from the subordinate lines, by 0.25-0.45 dex. The difference for each star is removed by taking into account the collisions with hydrogen atoms, and the rms error of the abundance derived from all seven Al I lines decreases by a factor of 1.5-3 compared to the LTE analysis. We have calculated the non- LTE corrections to the abundance for six subordinate Al I lines as a function of the effective temperature (4500 K ≤ T eff ≤ 6500 K

  7. The selective effect of environment on the atomic and molecular gas-to-dust ratio of nearby galaxies in the Herschel Reference Survey

    CERN Document Server

    Cortese, L; Boselli, A; Catinella, B; Ciesla, L; Hughes, T M; Baes, M; Bendo, G J; Boquien, M; de Looze, I; Smith, M W L; Spinoglio, L; Viaene, S

    2016-01-01

    We combine dust, atomic (HI) and molecular (H$_{2}$) hydrogen mass measurements for 176 galaxies in the Herschel Reference Survey to investigate the effect of environment on the gas-to-dust mass ($M_{\\rm gas}/M_{\\rm dust}$) ratio of nearby galaxies. We find that, at fixed stellar mass, the average $M_{\\rm gas}/M_{\\rm dust}$ ratio varies by no more than a factor of $\\sim$2 when moving from field to cluster galaxies, with Virgo galaxies being slightly more dust rich (per unit of gas) than isolated systems. Remarkably, once the molecular and atomic hydrogen phases are investigated separately, we find that \\hi-deficient galaxies have at the same time lower $M_{\\rm HI}/M_{\\rm dust}$ ratio but higher $M_{\\rm H_{2}}/M_{\\rm dust}$ ratio than \\hi-normal systems. In other words, they are poorer in atomic but richer in molecular hydrogen if normalized to their dust content. By comparing our findings with the predictions of theoretical models, we show that the opposite behavior observed in the $M_{\\rm HI}/M_{\\rm dust}$ a...

  8. Herschel-PACS observation of gas lines from the disc around HD141569A

    NARCIS (Netherlands)

    Thi, Wing-Fai; Pinte, Christophe; Pantin, Eric; Augereau, Jean-Charles; Meeus, Gwendolyn; Ménard, Francois; Martin-Zaidi, Claire; Woitke, Peter; Riviere-Marichalar, Pablo; Kamp, Inga; Carmona, Andres; Sandell, Goran; Eiroa, Carlos; Dent, William; Montesinos, Benjamin; Aresu, Giambattista; Meijerink, Rowin; Spaans, Marco; White, Glenn; Ardila, David; Lebreton, Jeremy; Mendigutia, Ignacio; Brittain, Sean

    2013-01-01

    At the distance of ˜ 99-116 pc, HD141569A is one of the nearest HerbigAe stars that is surrounded by a tenuous disc, probably in transition between a massive primordial disc and a debris disc. We observed the fine-structure lines of O I at 63 and 145 μm , and the C II line at 157 μm with the PACS in

  9. Harmonic generation by noble-gas atoms in the near-IR regime using ab initio time-dependent R -matrix theory

    Science.gov (United States)

    Hassouneh, O.; Brown, A. C.; van der Hart, H. W.

    2014-10-01

    We demonstrate the capability of ab initio time-dependent R -matrix theory to obtain accurate harmonic generation spectra of noble-gas atoms at near-IR wavelengths between 1200 and 1800 nm and peak intensities up to 1.8 × 10 14 W /cm 2. To accommodate the excursion length of the ejected electron, we use an angular-momentum expansion up to Lmax=279 . The harmonic spectra show evidence of atomic structure through the presence of a Cooper minimum in harmonic generation for Kr, and of multielectron interaction through the giant resonance for Xe. The theoretical spectra agree well with those obtained experimentally.

  10. Harmonic generation of noble-gas atoms in the Near-IR regime using ab-initio time-dependent R-matrix theory

    CERN Document Server

    Hassouneh, O; van der Hart, H W

    2014-01-01

    We demonstrate the capability of ab-initio time-dependent R-matrix theory to obtain accurate harmonic generation spectra of noble-gas atoms at Near-IR wavelengths between 1200 and 1800 nm and peak intensities up to 1.8 X 10(14) W/cm(2) . To accommodate the excursion length of the ejected electron, we use an angular-momentum expansion up to Lmax = 279. The harmonic spectra show evidence of atomic structure through the presence of a Cooper minimum in harmonic generation for Kr, and of multielectron interaction through the giant resonance for Xe. The theoretical spectra agree well with those obtained experimentally.

  11. Warm Gas in and Around Simulated Galaxy Clusters as Probed by Absorption Lines

    CERN Document Server

    Emerick, Andrew; Putman, Mary E

    2015-01-01

    Understanding gas flows into and out of the most massive dark matter structures in our Universe, galaxy clusters, is fundamental to understanding their evolution. Gas in clusters is well studied in the hot ($>$ 10$^{6}$ K) and cold ($<$ 10$^{4}$ K) regimes, but the warm gas component (10$^{4}$ - 10$^{6}$ K) is poorly constrained. It is challenging to observe directly, but can be probed through Ly$\\alpha$ absorption studies. We produce the first systematic study of the warm gas content of galaxy clusters through synthetic Ly$\\alpha$ absorption studies using cosmological simulations of two galaxy clusters produced with Enzo. We explore the spatial and kinematic properties of our cluster absorbers, and show that the majority of the identified absorbers are due to fast moving gas associated with cluster infall from IGM filaments. Towards the center of the clusters, however, the warm IGM filaments are no longer dominant and the absorbers tend to have higher column densities and metallicities, representing strip...

  12. Gas Pipelines, LP and LNG, Major Gas Lines - large lines in County. We are working on a distribution line for 911 purposes, Published in 2010, 1:2400 (1in=200ft) scale, Effingham County Board Of Commissioners.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Gas Pipelines, LP and LNG dataset, published at 1:2400 (1in=200ft) scale, was produced all or in part from Other information as of 2010. It is described as...

  13. On-line Detection of Gas Pipeline Based on the Real-Time Algorithm and Network Technology with Robot

    Institute of Scientific and Technical Information of China (English)

    YAN Bo; YAN Guo-zheng; DING Guo-qing; ZHOU Bing; FU Xi-guang; ZUO Jian-yong

    2004-01-01

    The detection system integrates control technology, network technology, video encoding and decoding, video transmiss-ion, multi-single chip microcomputer communication, dat-abase technology, computer software and robot technology. The robot can adaptively adjust its status according to diameter (from 400 mm to 650 mm) of pipeline. The maximum detection distance is up to 1 000 m. The method of video coding in the system is based on fractal transformation. The experiments show that the coding scheme is fast and good PSNR. The precision of on-line detection is up to 3% thickness of pipeline wall. The robot can also have a high precision of location up to 0.03 m. The control method is based on network and characterized by on-line and real-time. The experiment in real gas pipeline shows that the performance of the detection system is good.

  14. Microscopic Structure of a Vortex Line in a Dilute Superfluid Fermi Gas

    DEFF Research Database (Denmark)

    Nygaard, Nicolai; Bruun, G. M.; Clark, C. W.;

    2003-01-01

    The microscopic properties of a single vortex in a dilute superfluid Fermi gas at zero temperature are examined within the framework of self-consistent Bogoliubov–de Gennes theory. Using only physical parameters as input, we study the pair potential, the density, the energy, and the current...

  15. Vortex line in a neutral finite-temperature superfluid Fermi gas

    DEFF Research Database (Denmark)

    Nygaard, Nicolai; Bruun, G. M.; Schneider, B. I.;

    2004-01-01

    The structure of an isolated vortex in a dilute two-component neutral superfluid Fermi gas is studied within the context of self-consistent Bogoliubov-de Gennes theory. Various thermodynamic properties are calculated, and the shift in the critical temperature due to the presence of the vortex...

  16. Possibilities of mercury removal in the dry flue gas cleaning lines of solid waste incineration units.

    Science.gov (United States)

    Svoboda, Karel; Hartman, Miloslav; Šyc, Michal; Pohořelý, Michael; Kameníková, Petra; Jeremiáš, Michal; Durda, Tomáš

    2016-01-15

    Dry methods of the flue gas cleaning (for HCl and SO2 removal) are useful particularly in smaller solid waste incineration units. The amount and forms of mercury emissions depend on waste (fuel) composition, content of mercury and chlorine and on the entire process of the flue gas cleaning. In the case of high HCl/total Hg molar ratio in the flue gas, the majority (usually 70-90%) of mercury is present in the form of HgCl2 and a smaller amount in the form of mercury vapors at higher temperatures. Removal of both main forms of mercury from the flue gas is dependent on chemical reactions and sorption processes at the temperatures below approx. 340 °C. Significant part of HgCl2 and a small part of elemental Hg vapors can be adsorbed on fly ash and solid particle in the air pollution control (APC) processes, which are removed in dust filters. Injection of non-impregnated active carbon (AC) or activated lignite coke particles is able to remove mainly the oxidized Hg(2+) compounds. Vapors of metallic Hg(o) are adsorbed relatively weakly. Much better chemisorption of Hg(o) together with higher sorbent capacity is achieved by AC-based sorbents impregnated with sulfur, alkali poly-sulfides, ferric chloride, etc. Inorganic sorbents with the same or similar chemical impregnation are also applicable for deeper Hg(o) removal (over 85%). SCR catalysts convert part of Hg(o) into oxidized compounds (HgO, HgCl2, etc.) contributing to more efficient Hg removal, but excess of NH3 has a negative effect. Both forms, elemental Hg(o) and HgCl2, can be converted into HgS particles by reacting with droplets/aerosol of poly-sulfides solutions/solids in flue gas. Mercury captured in the form of water insoluble HgS is more advantageous in the disposal of solid waste from APC processes. Four selected options of the dry flue gas cleaning with mercury removal are analyzed, assessed and compared (in terms of efficiency of Hg-emission reduction and costs) with wet methods and retrofits for more

  17. Highly Adsorptive, MOF-Functionalized Nonwoven Fiber Mats for Hazardous Gas Capture Enabled by Atomic Layer Deposition

    Science.gov (United States)

    2014-03-20

    opportunities. Integration of MOFs on polymeric fibrous scaffolds will enable new applications in gas adsorption, membrane separation, catalysis...potential for gas adsorption and storage, their powder form limits deployment opportunities. Integration of MOFs on polymeric fibrous scaffolds will enable...MOFs on polymeric fi brous scaffolds will enable new applications in gas adsorption, membrane separation, catalysis, and toxic gas sensing. Here

  18. Study of Pair and many-body interactions in rare-gas halide atom clusters using negative ion zero electron kinetic energy (ZEKE) and threshold photodetachment spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yourshaw, Ivan [Univ. of California, Berkeley, CA (United States)

    1998-07-09

    The diatomic halogen atom-rare gas diatomic complexes KrBr-, XeBr-, and KrCl- are studied in this work by zero electron kinetic energy (ZEKE) spectroscopy in order to characterize the weak intermolecular diatomic potentials of these species. Also, the ZEKE and threshold photodetachment spectra of the polyatomic clusters ArnBr- (n = 2-9) and ArnI- (n = 2-19) are studied to obtain information about the non-additive effects on the interactions among the atoms. This work is part of an ongoing effort to characterize the pair and many-body potentials of the complete series of rare gas halide clusters. In these studies we obtain information about both the anionic and neutral clusters.

  19. Kinetics of the reaction of F atoms with Osub>2sub> and UV spectrum of FOsub>2sub> radicals in the gas phase at 295 K

    DEFF Research Database (Denmark)

    Ellermann, T.; Sehested, J.; Nielsen, O.J.

    1994-01-01

    The ultraviolet absorption spectrum of FO2 radicals and the kinetics of the reaction of F atoms with O2 have been studied in the gas phase at 295 K using pulse radiolysis combined with kinetic UV spectroscopy. At 230 nm, sigma(FO2) = (5.08 +/- 0.70) X 10(-18) cm2 molecule-1. The kinetics of the r......The ultraviolet absorption spectrum of FO2 radicals and the kinetics of the reaction of F atoms with O2 have been studied in the gas phase at 295 K using pulse radiolysis combined with kinetic UV spectroscopy. At 230 nm, sigma(FO2) = (5.08 +/- 0.70) X 10(-18) cm2 molecule-1. The kinetics...

  20. Ultrahigh-resolution spectroscopy with atomic or molecular dark resonances: Exact steady-state line shapes and asymptotic profiles in the adiabatic pulsed regime

    Energy Technology Data Exchange (ETDEWEB)

    Zanon-Willette, Thomas; Clercq, Emeric de; Arimondo, Ennio [UPMC Univ. Paris 06, UMR 7092, LPMAA, 4 place Jussieu, case 76, F-75005 Paris, France, and CNRS, UMR 7092, LPMAA, 4 place Jussieu, case 76, F-75005 Paris (France); LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 avenue de l' Observatoire, F-75014 Paris (France); Dipartimento di Fisica ' ' E. Fermi,' ' Universita di Pisa, Lgo. B. Pontecorvo 3, I-56122 Pisa (Italy)

    2011-12-15

    Exact and asymptotic line shape expressions are derived from the semiclassical density matrix representation describing a set of closed three-level {Lambda} atomic or molecular states including decoherences, relaxation rates, and light shifts. An accurate analysis of the exact steady-state dark-resonance profile describing the Autler-Townes doublet, the electromagnetically induced transparency or coherent population trapping resonance, and the Fano-Feshbach line shape leads to the linewidth expression of the two-photon Raman transition and frequency shifts associated to the clock transition. From an adiabatic analysis of the dynamical optical Bloch equations in the weak field limit, a pumping time required to efficiently trap a large number of atoms into a coherent superposition of long-lived states is established. For a highly asymmetrical configuration with different decay channels, a strong two-photon resonance based on a lower states population inversion is established when the driving continuous-wave laser fields are greatly unbalanced. When time separated resonant two-photon pulses are applied in the adiabatic pulsed regime for atomic or molecular clock engineering, where the first pulse is long enough to reach a coherent steady-state preparation and the second pulse is very short to avoid repumping into a new dark state, dark-resonance fringes mixing continuous-wave line shape properties and coherent Ramsey oscillations are created. Those fringes allow interrogation schemes bypassing the power broadening effect. Frequency shifts affecting the central clock fringe computed from asymptotic profiles and related to the Raman decoherence process exhibit nonlinear shapes with the three-level observable used for quantum measurement. We point out that different observables experience different shifts on the lower-state clock transition.

  1. Atomic level study of water-gas shift catalysts via transmission electron microscopy and x-ray spectroscopy

    Science.gov (United States)

    Akatay, Mehmed Cem

    Water-gas shift (WGS), CO + H2O ⇆ CO2 + H2 (DeltaH° = -41 kJ mol -1), is an industrially important reaction for the production of high purity hydrogen. Commercial Cu/ZnO/Al2O3 catalysts are employed to accelerate this reaction, yet these catalysts suffer from certain drawbacks, including costly regeneration processes and sulfur poisoning. Extensive research is focused on developing new catalysts to replace the current technology. Supported noble metals stand out as promising candidates, yet comprise intricate nanostructures complicating the understanding of their working mechanism. In this study, the structure of the supported Pt catalysts is explored by transmission electron microscopy and X-ray spectroscopy. The effect of the supporting phase and the use of secondary metals on the reaction kinetics is investigated. Structural heterogeneities are quantified and correlated with the kinetic descriptors of the catalysts to develop a fundamental understanding of the catalytic mechanism. The effect of the reaction environment on catalyst structure is examined by in-situ techniques. This study benefitted greatly from the use of model catalysts that provide a convenient medium for the atomic level characterization of nanostructures. Based on these studies, Pt supported on iron oxide nano islands deposited on inert spherical alumina exhibited 48 times higher WGS turnover rate (normalized by the total Pt surface area) than Pt supported on bulk iron oxide. The rate of aqueous phase glycerol reforming reaction of Pt supported on multiwall carbon nanotubes (MWCNT) is promoted by co-impregnating with cobalt. The synthesis resulted in a variety of nanostructures among which Pt-Co bimetallic nanoparticles are found to be responsible for the observed promotion. The unprecedented WGS rate of Pt supported on Mo2C is explored by forming Mo 2C patches on top of MWCNTs and the rate promotion is found to be caused by the Pt-Mo bimetallic entities.

  2. Dispersion coefficients for the interactions of the alkali and alkaline-earth ions and inert gas atoms with a graphene layer

    CERN Document Server

    Kaur, Kiranpreet; Sahoo, B K

    2015-01-01

    Largely motivated by a number of applications, the van der Waals dispersion coefficients ($C_3$s) of the alkali ions (Li$^+$, Na$^+$, K$^+$ and Rb$^+$), the alkaline-earth ions (Ca$^+$, Sr$^+$, Ba$^+$ and Ra$^+$) and the inert gas atoms (He, Ne, Ar and Kr) with a graphene layer are determined precisely within the framework of Dirac model. For these calculations, we have evaluated the dynamic polarizabilities of the above atomic systems very accurately by evaluating the transition matrix elements employing relativistic many-body methods and using the experimental values of the excitation energies. The dispersion coefficients are, finally, given as functions of the separation distance of an atomic system from the graphene layer and the ambiance temperature during the interactions. For easy extraction of these coefficients, we give a logistic fit to the functional forms of the dispersion coefficients in terms of the separation distances at the room temperature.

  3. Effect of Mg/Al atom ratio of support on catalytic performance of Co-Mo/MgO-Al2O3 catalyst for water gas shift reaction

    Institute of Scientific and Technical Information of China (English)

    Yixin Lian; Huifang Wang; Quanxing Zheng; Weiping Fang; Yiquan Yang

    2009-01-01

    Co-Mo-based catalysts supported on mixed oxide supports MgO-Al2O3 with different Mg/Al atom ratios for water gas shift reaction were studied by means of TPR, Raman, XPS and ESR. It was found that the octahedral Mo species in oxidized Co-Mo/MgO(x)-Al2O3 catalyst and the contents of Mo5+, Mo4+, S2- and S2-2 species in the functioning catalysts increased with increasing the Mg/Al atom ratio of the support under the studied experimental conditions. This is favorable for the formation of the active Co-Mo-S phase of the catalysts. Catalytic performance testing results showed that the catalysts Co-Mo/MgO-Al2O3 with the Mg/Al atom ratio of the support in the range of 0.475-0.525 exhibited optimal catalytic activity for the reaction.

  4. Volatile organo-selenium speciation in biological matter by solid phase microextraction–moderate temperature multicapillary gas chromatography with microwave induced plasma atomic emission spectrometry detection

    OpenAIRE

    Dietz, Christian; Sanz Landaluze, Jon; Ximenez Embun, Pilar; Madrid Albarrán, Yolanda; Cámara, Carmen

    2004-01-01

    Microwave induced plasma atomic emission spectrometry (MIP-AES) in combination with multicapillary (MC) gas chromatography could be proven to be useful for element specific detection of volatile species. Solid phase microextraction (SPME) was used for preconcentration and sample-matrix separation. The fiber desorption unit as well as the heating control for the MCcolumn were in-house developed and multicapillary column was operated at moderate temperatures (30–100 ◦C). The method was...

  5. Atmospheric chemistry of trans-CF3CH=CHCl: Kinetics of the gas-phase reactions with Cl atoms, OH radicals, and O3

    DEFF Research Database (Denmark)

    Andersen, Mads Peter Sulbaek; Nilsson, Elna Johanna Kristina; Nielsen, Ole John;

    2008-01-01

    Long path length Fourier transform infrared (FTIR)–smog chamber techniques were used to study the kinetics of the gas-phase reactions of Cl atoms, OH radicals and O3 with trans-3,3,3-trifluoro-1-chloropropene, t-CF3CH CHCl, in 700 Torr total pressure at 295±2K. Values of k(Cl + t-CF3CH CHCl) = (5...

  6. Intramolecular bond length dependence of the anisotropic dispersion coefficients for interactions of rare gas atoms with N2, CO, Cl2, HCl and HBr

    Science.gov (United States)

    Hettema, Hinne; Wormer, Paul E. S.; Thakkar, Ajit J.

    Ab initio many body perturbation theory is used to calculate the imaginary frequency multipole polarizabilities of N2, Cl2, CO, HCl and HBr as a function of bond length. These are combined with previously calculated dynamic polarizabilities for rare gas atoms to obtain the intramolecular bond length dependence of the anisotropic dispersion and induction coefficients through R-8 for AB-X (AB = N2, Cl2, CO, HCl, HBr and X = He, Ne, Ar, Kr, Xe) interactions.

  7. Combination of the ionic-to-atomic line intensity ratios from two test elements for the diagnostic of plasma temperature and electron number density in Inductively Coupled Plasma Atomic Emission Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tognoni, E. [Istituto per i Processi Chimico-Fisici, Area della Ricerca del Consiglio Nazionale delle Ricerche Via Moruzzi 1, 56124 Pisa (Italy)], E-mail: tognoni@ipcf.cnr.it; Hidalgo, M.; Canals, A. [Departamento de Quimica Analitica, Nutricion y Bromatologia. Universidad de Alicante. Apdo. 99, 03080, Alicante (Spain); Cristoforetti, G.; Legnaioli, S.; Salvetti, A.; Palleschi, V. [Istituto per i Processi Chimico-Fisici, Area della Ricerca del Consiglio Nazionale delle Ricerche Via Moruzzi 1, 56124 Pisa (Italy)

    2007-05-15

    In Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) spectrochemical analysis, the MgII(280.270 nm)/MgI(285.213 nm) ionic to atomic line intensity ratio is commonly used as a monitor of the robustness of operating conditions. This approach is based on the univocal relationship existing between intensity ratio and plasma temperature, for a pure argon atmospheric ICP in thermodynamic equilibrium. In a multi-elemental plasma in the lower temperature range, the measurement of the intensity ratio may not be sufficient to characterize temperature and electron density. In such a range, the correct relationship between intensity ratio and plasma temperature can be calculated only when the complete plasma composition is known. We propose the combination of the line intensity ratios of two test elements (double ratio) as an effective diagnostic tool for a multi-elemental low temperature LTE plasma of unknown composition. In particular, the variation of the double ratio allows us discriminating changes in the plasma temperature from changes in the electron density. Thus, the effects on plasma excitation and ionization possibly caused by introduction of different samples and matrices in non-robust conditions can be more accurately interpreted. The method is illustrated by the measurement of plasma temperature and electron density in a specific analytic case.

  8. Characterization and analysis of weld lines on micro-injection moulded parts using atomic force microscopy (AFM)

    DEFF Research Database (Denmark)

    Tosello, Guido; Gava, Alberto; Hansen, Hans Nørgaard

    2009-01-01

    In recent years plastic moulding techniques, such as injection moulding, have been developed to fulfil the needs of micro-components fabrication. Micro-injection moulding (SLIM) is the process which enables the mass production of polymer micro-systems such as micro-mechanical parts, micro...... the two original flows will generate and a weld line is formed on the surface of the micro-moulded part. This phenomenon has to be avoided or at least reduced, since in the weld line area the mechanical properties are poorer than in the bulk part, creating strength problems on the final part. Although...... weld lines are unavoidable, the micro-injection moulding process can indeed be optimized in order to on one hand obtain a good filling of the cavity and on the other hand decrease the size of the weld lines. In this paper, an investigation devoted to the determination of the influence of typical...

  9. Measurements of radiation near an atomic spectral line from the interaction of a 30 GeV electron beam and a long plasma

    Energy Technology Data Exchange (ETDEWEB)

    Catravas, P.; Chattopadhyay, S.; Esarey, E.; Leemans, W. P.; Assmann, R.; Decker, F.-J.; Hogan, M. J.; Iverson, R.; Siemann, R. H.; Walz, D. (and others)

    2001-10-01

    Emissions produced or initiated by a 30-GeV electron beam propagating through a {approx}1-m long heat pipe oven containing neutral and partially ionized vapor have been measured near atomic spectral lines in a beam-plasma wakefield experiment. The Cerenkov spatial profile has been studied as a function of oven temperature and pressure, observation wavelength, and ionizing laser intensity and delay. The Cerenkov peak angle is affected by the creation of plasma, and estimates of neutral and plasma density have been extracted. Increases in visible background radiation, consistent with increased plasma recombination emissions due to dissipation of wakefields, were simultaneously measured.

  10. Measurements of Radiation Near An Atomic Spectral Line From the Interaction of a 30-GeV Electron Beam And a Long Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Catravas, P.; Chattopadhyay, S.; Esarey, E.; Leemans, W.P.; /LBL, Berkeley; Assmann, R.; Decker, F.J.; Hogan, M.J.; Iverson, R.; Siemann, R.H.; Walz, D.; Whittum, D.; /SLAC; Blue, B.; Clayton, C.; Joshi, C.; Marsh, K.A.; Mori, W.B.; Wang, S.; /UCLA; Katsouleas, T.; Lee, S.; Muggli, P.; /Southern California U.

    2005-09-12

    Emissions produced or initiated by a 30 GeV electron beam propagating through a {approx}1 m long heat pipe oven containing neutral and partially ionized vapor have been measured near atomic spectral lines in a beam-plasma wakefield experiment. The Cerenkov spatial profile has been studied as a function of oven temperature and pressure, observation wavelength, and ionizing laser intensity and delay. The Cerenkov peak angle is affected by the creation of plasma; estimates of plasma and neutral density have been extracted. Increases in visible background radiation consistent with increased plasma recombination emissions due to dissipation of wakefields were simultaneously measured.

  11. Measurements of radiation near an atomic spectral line from the interaction of a 30 GeV electron beam and a long plasma

    Energy Technology Data Exchange (ETDEWEB)

    Catravas, P.E.; Chattopadhyay, S.; Esarey, E.; Leemans, W.P.; Assmann, R.; Decker, F.-J.; Hogan, M.J.; Iverson, R.; Siemann, R.H.; Walz, D.; Whittum, D.; Blue, B.; Clayton, C; Joshi, C.; Marsh, K.A.; Mori, W.B.; Wang, S.; Katsouleas, T.; Lee, S.; Muggli, P.

    2000-10-31

    Emissions produced or initiated by a 30 GeV electron beam propagating through a {approx} 1 m long heat pipe oven containing neutral and partially ionized vapor have been measured near atomic spectral lines in a beam-plasma wakefield experiment. The Cerenkov spatial profile has been studied as a function of oven temperature and pressure, observation wavelength, and ionizing laser intensity and delay. The Cerenkov peak angle is affected by the creating of plasma, and estimates of neutral and plasma density have been extracted. Increases in visible background radiation, consistent with increased plasma recombination emissions due to dissipation of wakefields, were simultaneously measured.

  12. Measurements of radiation near an atomic spectral line from the interaction of a 30 GeV electron beam and a long plasma

    Science.gov (United States)

    Catravas, P.; Chattopadhyay, S.; Esarey, E.; Leemans, W. P.; Assmann, R.; Decker, F.-J.; Hogan, M. J.; Iverson, R.; Siemann, R. H.; Walz, D.; Whittum, D.; Blue, B.; Clayton, C.; Joshi, C.; Marsh, K. A.; Mori, W. B.; Wang, S.; Katsouleas, T.; Lee, S.; Muggli, P.

    2001-10-01

    Emissions produced or initiated by a 30-GeV electron beam propagating through a ~1-m long heat pipe oven containing neutral and partially ionized vapor have been measured near atomic spectral lines in a beam-plasma wakefield experiment. The Cerenkov spatial profile has been studied as a function of oven temperature and pressure, observation wavelength, and ionizing laser intensity and delay. The Cerenkov peak angle is affected by the creation of plasma, and estimates of neutral and plasma density have been extracted. Increases in visible background radiation, consistent with increased plasma recombination emissions due to dissipation of wakefields, were simultaneously measured.

  13. Carbon isotope ratio analysis of organic moieties from fossil mummified wood: establishing optimum conditions for off-line pyrolysis extraction using gas chromatography/mass spectrometry

    NARCIS (Netherlands)

    Poole, I.J.; Bergen, P.F. van

    2002-01-01

    Mummified fossil wood was studied using off-line pyrolysis-gas chromatography/mass spectrometry to reveal detailed insights into the pyrolysis conditions that are needed to obtain simultaneously sufficient amounts of both cellulose and lignin markers for stable carbon isotope analyses. The off-line

  14. Thermostability analysis of line-tension-associated nucleation at a gas-liquid interface

    Science.gov (United States)

    Singha, Sanat Kumar; Das, Prasanta Kumar; Maiti, Biswajit

    2017-01-01

    The influence of line tension on the thermostability of a droplet nucleated from an oversaturated vapor at the interface of the vapor and another immiscible liquid is investigated. Along with the condition of mechanical equilibrium, the notion of extremization of the reversible work of formation is considered to obtain the critical parameters related to heterogeneous nucleation. From the energetic formulation, the critical reversible work of formation is found to be greater than that of homogeneous nucleation for high value of the positive line tension. On the other hand, for high value of the negative line tension, the critical reversible work of formation becomes negative. Therefore, these thermodynamic instabilities under certain substrate wettability situations necessitate a free-energetics-based stability of the nucleated droplet, because the system energy is not minimized under these conditions. This thermostability is analogous to the transition-based stability proposed by Widom [B. Widom, J. Phys. Chem. 99, 2803 (1995)], 10.1021/j100009a041 in the case of partial wetting phenomena along with the positive line tension. The thermostability analysis limits the domain of the solution space of the present critical-value problem as the thermodynamic transformation in connection with homogeneous and workless nucleation is considered. Within the stability range of the geometry-based wetting parameters, three limiting modes of nucleation, i.e., total-dewetting-related homogeneous nucleation, and total-wetting-associated and total-submergence-associated workless nucleation scenarios, are identified. Either of the two related limiting wetting scenarios of workless nucleation, namely, total wetting and total submergence, is found to be favorable depending on the geometry-based wetting conditions. The line-tension-associated nucleation on a liquid surface can be differentiated from that on a rigid substrate, as in the former, the stability based on mechanical

  15. Low symmetry in molecules with heavy peripheral atoms. The gas-phase structure of perfluoro(methylcyclohexane), C6F11CF3.

    Science.gov (United States)

    Kafka, Graeme R; Masters, Sarah L; Wann, Derek A; Robertson, Heather E; Rankin, David W H

    2010-10-21

    When refining structures using gas electron diffraction (GED) data, assumptions are often made in order to reduce the number of required geometrical parameters. Where these relate to light, peripheral atoms there is little effect on the refined heavy-atom structure, which is well defined by the GED data. However, this is not the case when heavier atoms are involved. We have determined the gas-phase structure of perfluoro(methylcyclohexane), C(6)F(11)CF(3), using three different refinement methods and have shown that our new method, which makes use of both MP2 and molecular mechanics (MM) calculations to restrain the peripheral-atom geometry, gives a realistic structure without the need for damaging constraints. Only the conformer with the CF(3) group in an equatorial position was considered, as ab initio calculations showed this to be 25 kJ mol(-1) lower in energy than the axial conformer. Refinements combining both high-level and low-level calculations to give constraints were superior both to those based only on molecular mechanics and to those in which assumptions about the geometry were imposed.

  16. Spectral line broadening of Sr under the influence of collisions with foreign gas perturbers

    Science.gov (United States)

    Makdisi, Y.

    1997-02-01

    The collision broadening of strontium Rydberg states under the influence of Xe, Ar and He gases has been studied by laser spectroscopy of two-photon excitation of Sr in a heat pipe. Broadening data for the 5s nd 1D 2 series are reported with buffer gas pressure in the range of 10 Torr to 500 Torr. Observed anomalies in broadening parameters due to inter-configuration perturbation are discussed.

  17. Multi Parameter Flow Meter for On-Line Measurement of Gas Mixture Composition

    Directory of Open Access Journals (Sweden)

    Egbert van der Wouden

    2015-04-01

    Full Text Available In this paper we describe the development of a system and model to analyze the composition of gas mixtures up to four components. The system consists of a Coriolis mass flow sensor, density, pressure and thermal flow sensor. With this system it is possible to measure the viscosity, density, heat capacity and flow rate of the medium. In a next step the composition can be analyzed if the constituents of the mixture are known. This makes the approach universally applicable to all gasses as long as the number of components does not exceed the number of measured properties and as long as the properties are measured with a sufficient accuracy. We present measurements with binary and ternary gas mixtures, on compositions that range over an order of magnitude in value for the physical properties. Two platforms for analyses are presented. The first platform consists of sensors realized with MEMS fabrication technology. This approach allows for a system with a high level of integration. With this system we demonstrate a proof of principle for the analyses of binary mixtures with an accuracy of 10%. In the second platform we utilize more mature steel sensor technology to demonstrate the potential of this approach. We show that with this technique, binary mixtures can be measured within 1% and ternary gas mixtures within 3%.

  18. The influence of spill-line geometry on a spray generated by a pressure-swirl atomizer

    Directory of Open Access Journals (Sweden)

    Malý Milan

    2016-01-01

    Full Text Available An experimental investigation of characteristics of spray generated by a pressure-swirl atomizer (spill-return type was performed using shadowgraphy and Phase-Doppler Anemometry (PDA. Several different geometries of the spill-return orifice were tested in terms of a spray stability and quality on a cold test bench. PDA measurement yields a drop-size distribution and velocity data while the shadowgraphy unveils a break-up process in detail. Performed measurements reveal significant differences in spray characteristics as well as differences in spray stability. The results suggest that the air core, formed inside the swirl chamber, passes through the spill orifice, which causes instability of the inner flow. These instabilities lead to a chaotic state of sheet breakup resulting in shortening of breakup distance. Obtained findings are used to propose possible changes in the atomizer design for improvement of its performance.

  19. Molecular line emission in NGC1068 imaged with ALMA: II. The chemistry of the dense molecular gas

    CERN Document Server

    Viti, S; Fuente, A; Hunt, L K; Usero, A; Henkel, C; Eckart, A; Martin, S; Spaans, M; Muller, S; Combes, F; Krips, M; Schinnerer, E; Casasola, V; Costagliola, F; Marquez, I; Planesas, P; van der Werf, P P; Aalto, S; Baker, A J; Boone, F; Tacconi, L J

    2014-01-01

    We present a detailed analysis of ALMA Bands 7 and 9 data of CO, HCO+, HCN and CS, augmented with Plateau de Bure Interferometer (PdBI) data of the ~ 200 pc circumnuclear disk (CND) and the ~ 1.3 kpc starburst ring (SB ring) of NGC~1068, a nearby (D = 14 Mpc) Seyfert 2 barred galaxy. We aim at determining the physical characteristics of the dense gas present in the CND and whether the different line intensity ratios we find within the CND as well as between the CND and the SB ring are due to excitation effects (gas density and temperature differences) or to a different chemistry. We estimate the column densities of each species in Local Thermodynamic Equilibrium (LTE). We then compute large one-dimensional non-LTE radiative transfer grids (using RADEX) by using first only the CO transitions, and then all the available molecules in order to constrain the densities, temperatures and column densities within the CND. We finally present a preliminary set of chemical models to determine the origin of the gas. We fi...

  20. Absorption spectrum of very low pressure atomic hydrogen

    CERN Document Server

    Moret-Bailly, Jacques

    2015-01-01

    Spectra of quasars result primarily from interactions of natural light with atomic hydrogen. A visible absorption of a sharp and saturated spectral line in a gas requires a low pressure, so a long path without blushing as a cosmological redshift. Burbidge and Karlsson observed that redshifts of quasars result from fundamental redshifts, written 3K and 4K, that cause a shift of absorbed beta and gamma lines of H to alpha gas line. Thus absorbed spectrum is shifted until an absorbed line overlaps with Lyman alpha line of gas: redshift only occurs if an alpha absorption pumps atoms to 2P state. Thus, space is divided into spherical shells centered on the quasar, containing or not 2P atoms. Neglecting collisional de-excitations in absorbing shells, more and more atoms are excited until amplification of a beam having a long path in a shell, thus perpendicular to the observed ray, is large enough for a superradiant flash at alpha frequency. Energy is provided by atoms and observed ray, absorbing a line at local Lym...

  1. Influence of Inelastic Collisions with Hydrogen Atoms on the Formation of Al I and Si I Lines in Stellar Spectra

    CERN Document Server

    Mashonkina, Lyudmila; Shi, Jianrong

    2016-01-01

    The non-LTE line formation for Al I and Si I was calculated with model atmospheres corresponding to F-G-K type stars of different metallicity. To account for inelastic collisions with H I, for the first time we applied the cross sections calculated by Belyaev et al. using model approaches within the formalism of the Born-Oppenheimer quantum theory. For Al I non-LTE leads to overionization in the line formation layers and to weakened spectral lines, in line with earlier non-LTE studies. However, in contrast to the previuos studies, our results predict smaller magnitude of the non-LTE effects for the subordinate lines. Owing to large cross sections, the ion-pair production and mutual neutralization processes Al I(nl) + H I(1s) $\\leftrightarrow$ Al~II(3s^2) + H^- provide a close coupling of high-excitation Al I levels to the Al II ground state, which causes smaller deviations from the TE populations compared to the case of pure electron collisions. For three metal-poor stars, the Al abundance was determined from...

  2. A Multi-line Study of Atomic Carbon and Carbon Monoxide in the Galactic Star- forming Region W3

    Science.gov (United States)

    Jakob, H.; Kramer, C.; Mookerjea, B.; Jeyakumar, S.; Stutzki, J.

    We present results from simultaneous observations of the fine structure line emissions of neutral carbon (C I) at 492 and 809 GHz from selected Galactic star forming regions. These observations include the first results using the the newly installed SMART (SubmilliMeter Array Receiver at Two wavelengths) on KOSMA. The regions observed were selected in order to cover a range of strengths of the incident UV radiation from the exciting star/stars and also densities of the interstellar medium. Extended maps of C I emission from massive star forming regions including W3, S106 and Orion BN/KL have been observed. Simultaneous observation of the two C I lines ensures better relative calibration. The results from these observations will be combined with observed intensities of low-J and mid-J CO and C+ lines and analyzed using radiation transfer based models for Photon Dominated Regions (PDRs).

  3. Characterization of the shape and line-edge roughness of polymer gratings with grazing incidence small-angle X-ray scattering and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Hyo Seon; Chen, Xuanxuan; Rincon-Delgadillo, Paulina A.; Jiang, Zhang; Strzalka, Joseph; Wang, Jin; Chen, Wei; Gronheid, Roel; de Pablo, Juan J.; Ferrier, Nicola; Doxastakis, Manolis; Nealey, Paul F.

    2016-04-22

    Grazing-incidence small-angle X-ray scattering (GISAXS) is increasingly used for the metrology of substrate-supported nanoscale features and nanostructured films. In the case of line gratings, where long objects are arranged with a nanoscale periodicity perpendicular to the beam, a series of characteristic spots of high-intensity (grating truncation rods, GTRs) are recorded on a two-dimensional detector. The intensity of the GTRs is modulated by the three-dimensional shape and arrangement of the lines. Previous studies aimed to extract an average cross-sectional profile of the gratings, attributing intensity loss at GTRs to sample imperfections. Such imperfections are just as important as the average shape when employing soft polymer gratings which display significant line-edge roughness. Herein are reported a series of GISAXS measurements of polymer line gratings over a range of incident angles. Both an average shape and fluctuations contributing to the intensity in between the GTRs are extracted. The results are critically compared with atomic force microscopy (AFM) measurements, and it is found that the two methods are in good agreement if appropriate corrections for scattering from the substrate (GISAXS) and contributions from the probe shape (AFM) are accounted for.

  4. Broad Balmer Absorption Line Variability: Evidence of Gas Transverse Motion in the QSO SDSS J125942.80+121312.6

    CERN Document Server

    Shi, Xiheng; Shu, Xinwen; Zhang, Shaohua; Ji, Tuo; Pan, Xiang; Sun, Luming; Zhao, Wen; Hao, Lei

    2016-01-01

    We report on the discovery of broad Balmer absorption lines variability in the QSO SDSS J125942.80+121312.6, based on the optical and near-infrared spectra taken from the SDSS-I, SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), and TripleSpec observations over a timescale of 5.8 years in the QSO's rest-frame. The blueshifted absorption profile of H$\\beta$ shows a variation of more than 5$\\sigma$ at a high velocity portion ($>3000\\ \\mathrm{km\\ s}^{-1}$) of the trough. We perform a detailed analysis for the physical conditions of the absorber using Balmer lines as well as metastable He I and optical Fe II absorptions ($\\lambda 4233$ from b$^4$P$_{5/2}$ level and $\\lambda 5169$ from a$^6$S$_{5/2}$) at the same velocity. These Fe II lines are identified in the QSO spectra for the first time. According to the photoionization simulations, we estimate a gas density of $n(\\mathrm{H})\\approx 10^{9.1}\\ \\mathrm{cm}^{-3}$ and a column density of $N_{\\mathrm{col}}(\\mathrm{H})\\approx 10^{23}\\ \\mathrm{cm}^{-2}$ for ...

  5. Surpassing the mass restriction of buffer gas cooling: Cooling of low mass ions by localized heavier atoms

    Science.gov (United States)

    Dutta, Sourav; Sawant, Rahul; Rangwala, S. A.

    2016-05-01

    Cooling of trapped ions has resulted in fascinating science including the realization of some of the most accurate atomic clocks. It has also found widespread application, for example, in mass spectrometry and cold chemistry. Among the different methods for cooling ions, cooling by elastic collisions with ultracold neutral atoms is arguably the most generic. However, in spite of its widespread application, there is confusion with regards the collisional heating/cooling of light ions by heavier neutral atoms. We address the question experimentally and demonstrate, for the first time, cooling of light ions by co-trapped heavy atoms. We show that trapped 39 K+ ions are cooled by localized ultracold neutral 85 Rb atoms. The atom-ion mass ratio (= 2.18) is well beyond any theoretical predictions so far. We further argue that cooling of ions by localized cold atoms is possible for any mass ratio. The result opens up the possibility of reaching the elusive s-wave collision regime in atom-ion collisions. S.D. is supported by DST-INSPIRE Faculty Fellowship, India.

  6. Optimization of Simplex Atomizer Inlet Port Configuration through Computational Fluid Dynamics and Experimental Study for Aero-Gas Turbine Applications

    Science.gov (United States)

    Marudhappan, Raja; Chandrasekhar, Udayagiri; Hemachandra Reddy, Koni

    2016-06-01

    The design of plain orifice simplex atomizer for use in the annular combustion system of 1100 kW turbo shaft engine is optimized. The discrete flow field of jet fuel inside the swirl chamber of the atomizer and up to 1.0 mm downstream of the atomizer exit are simulated using commercial Computational Fluid Dynamics (CFD) software. The Euler-Euler multiphase model is used to solve two sets of momentum equations for liquid and gaseous phases and the volume fraction of each phase is tracked throughout the computational domain. The atomizer design is optimized after performing several 2D axis symmetric analyses with swirl and the optimized inlet port design parameters are used for 3D simulation. The Volume Of Fluid (VOF) multiphase model is used in the simulation. The orifice exit diameter is 0.6 mm. The atomizer is fabricated with the optimized geometric parameters. The performance of the atomizer is tested in the laboratory. The experimental observations are compared with the results obtained from 2D and 3D CFD simulations. The simulated velocity components, pressure field, streamlines and air core dynamics along the atomizer axis are compared to previous research works and found satisfactory. The work has led to a novel approach in the design of pressure swirl atomizer.

  7. Absorption Line Study of Halo Gas in NGC 3067 Toward the Background Quasar 3C 232

    CERN Document Server

    Keeney, B A; Stocke, J T; Carilli, C L; Tumlinson, J; Keeney, Brian A.; Momjian, Emmanuel; Stocke, John T.; Carilli, Chris L.; Tumlinson, Jason

    2004-01-01

    We present new H I 21 cm absorption data and ultraviolet spectroscopy from HST/STIS of the QSO/galaxy pair 3C 232/NGC 3067. The QSO sightline lies near the minor axis and 1.8 arcmin (11 kpc) above the plane of NGC 3067, a nearby luminous (cz = 1465 km/s, L = 0.5L*) starburst galaxy with a moderate star formation rate of 1.4 Solar masses per year. The UV spectra show that the Si IV and C IV doublets have the same three velocity components at cz = 1369, 1417, and 1530 km/s found in Ca II H & K, Na I D, Mg I, Mg II, and Fe II, implying that the low and high ionization gas are both found in three distinct absorbing clouds (only the strongest component at 1420 km/s is detected in H I 21 cm). The new Lyman alpha observation allows the first measurements of the spin and kinetic temperatures of halo gas: T_s = 435 +/- 140 K and T_k/T_s ~ 1. However, while a standard photoionization model can explain the low ions, the C IV and Si IV are explained more easily as collisionally-ionized boundary layers of the photoion...

  8. Dynamic analysis on atomized gas in limited and unlimited structures%限制式与非限制式结构雾化气体动力学分析

    Institute of Scientific and Technical Information of China (English)

    曲迎东; 刘同帮; 孙鑫志; 李荣德; 白彦华

    2012-01-01

    The numerical simulation for the flow field of atomized gas in two typical atomizing structures,namely limited and unlimited structures,was performed.According to the simulation results,the distribution of atomization gas flow field in two structures and the change rule of individual parameter on the axial line were analyzed.In addition,the same and different points of gas behavior in two structures were pointed out through performing the comparison.The results show that the backflow regions can form in two structures,but the morphologies of backflow regions are different.Moreover,the backflow strength in the limited structure is higher,and the decrease in the temperature of backflow region is more obvious.A stagnation point with zero velocity appears below the backflow region,but is not the maximum pressure point in the gas field.The maximum pressure point locates at the region below the stagnation point,and is the convergent point of main flow at the jet-flow center.In the spaying process,the atomized gas flow will move in an oscillation mode,and the oscillation amplitude of the gas flow in the limited structure is bigger.With increasing the spaying distance,the oscillation of the gas flow weakens.%针对两种典型雾化结构:限制式和非限制式结构,对其各自的雾化气体流场进行了数值模拟.根据模拟结果,分析了两种结构雾化器气体流场的分布情况及轴线处各参数变化规律,并通过对比指出了两种结构气体行为的同异之处.结果表明:两种结构均能形成回流区,但回流区形貌不同,且限制式结构回流强度更高,回流区温度降低更明显;回流区的下方存在一个速度为0的滞止点,但滞止点并非气场中压力最大值点,压力最大值点在滞止点的下方区域,是射流中心主流的交汇点.在喷射过程中,雾化气流会以振荡形式运动,限制式结构气流振荡幅度较大,随喷射距离增加,气流的振荡减弱.

  9. Collisional Broadening and Shift of D1 and D2 Spectral Lines in Atomic Alkali Vapor - Noble Gas Systems

    Science.gov (United States)

    2013-03-01

    broadening using a WKB approximation in a semiclassical approach (Weisskopf, 1932a, 1932b), and Jabloński, who also used a WKB approximation but treated...appropriate, compiled and executed on AFIT’s Linux Cluster and on supercomputers run by the DoD High Performance Computing Modernization Program...The result is a cross section that decays with increasing temperature; we expect that a greater kinetic energy results in a lesser fractional change

  10. Propagation of the initial value perturbation in a cylindrical lined duct carrying a gas flow

    Directory of Open Access Journals (Sweden)

    Agneta M. BALINT

    2013-03-01

    Full Text Available For the homogeneous Euler equation linearized around a non-slipping mean flow andboundary conditions corresponding to the mass-spring-damper impedance, smooth initial dataperturbations with compact support are considered. The propagation of this type of initial dataperturbations in a straight cylindrical lined duct is investigated. Such kind of investigations is missingin the existing literature. The mathematical tools are the Fourier transform with respect to the axialspatial variable and the Laplace transform with respect to the time variable. The functionalframework and sufficient conditions are researched that the so problem be well-posed in the sense ofHadamard and the Briggs-Bers stability criteria can be applied.

  11. Molecular line emission in NGC 1068 imaged with ALMA. II. The chemistry of the dense molecular gas

    Science.gov (United States)

    Viti, S.; García-Burillo, S.; Fuente, A.; Hunt, L. K.; Usero, A.; Henkel, C.; Eckart, A.; Martin, S.; Spaans, M.; Muller, S.; Combes, F.; Krips, M.; Schinnerer, E.; Casasola, V.; Costagliola, F.; Marquez, I.; Planesas, P.; van der Werf, P. P.; Aalto, S.; Baker, A. J.; Boone, F.; Tacconi, L. J.

    2014-10-01

    Aims: We present a detailed analysis of Atacama Large Millimeter/submillimeter Array (ALMA) Bands 7 and 9 data of CO, HCO+, HCN, and CS, augmented with Plateau de Bure Interferometer (PdBI) data of the ~200 pc circumnuclear disc (CND) and the ~1.3 kpc starburst ring (SB ring) of NGC 1068, a nearby (D = 14 Mpc) Seyfert 2 barred galaxy. We aim to determine the physical characteristics of the dense gas present in the CND, and to establish whether the different line intensity ratios we find within the CND, as well as between the CND and the SB ring, are due to excitation effects (gas density and temperature differences) or to a different chemistry. Methods: We estimate the column densities of each species in local thermodynamic equilibrium (LTE). We then compute large one-dimensional, non-LTE radiative transfer grids (using RADEX) by using only the CO transitions first, and then all the available molecules to constrain the densities, temperatures, and column densities within the CND. We finally present a preliminary set of chemical models to determine the origin of the gas. Results: We find that, in general, the gas in the CND is very dense (>105 cm-3) and hot (T> 150 K), with differences especially in the temperature across the CND. The AGN position has the lowest CO/HCO+, CO/HCN, and CO/CS column density ratios. The RADEX analyses seem to indicate that there is chemical differentiation across the CND. We also find differences between the chemistry of the SB ring and some regions of the CND; the SB ring is also much colder and less dense than the CND. Chemical modelling does not succeed in reproducing all the molecular ratios with one model per region, suggesting the presence of multi-gas phase components. Conclusions: The LTE, RADEX, and chemical analyses all indicate that more than one gas-phase component is necessary to uniquely fit all the available molecular ratios within the CND. A higher number of molecular transitions at the ALMA resolution is necessary to

  12. The Unique Gas-Phase Chemistry of the [AuO](+) /CH4 Couple: Selective Oxygen-Atom Transfer to, Rather than Hydrogen-Atom Abstraction from, Methane.

    Science.gov (United States)

    Zhou, Shaodong; Li, Jilai; Schlangen, Maria; Schwarz, Helmut

    2016-08-26

    The thermal reaction of [AuO](+) with methane has been explored using FT-ICR mass spectrometry complemented by high-level quantum chemical calculations. In contrast to the previously studied congener [CuO](+) , and to [AgO](+) , [AuO](+) reacts with CH4 exclusively via oxygen-atom transfer to form CH3 OH, and a novel mechanistic scenario for this selective oxidation process has been revealed. Also, the origin of the inertness of the [AgO](+) /CH4 couple has been addressed computationally.

  13. An all-optical locking of a semiconductor laser to the atomic resonance line with 1 MHz accuracy.

    Science.gov (United States)

    Zhang, Xiaogang; Tao, Zhiming; Zhu, Chuanwen; Hong, Yelong; Zhuang, Wei; Chen, Jingbiao

    2013-11-18

    An all-optical locking technique without extra electrical feedback control system for a semiconductor laser has been used in stabilizing the laser frequency to a hyperfine crossover transition of 87Rb 5(2)S(1/2), F = 2 → 5(2)P(3/2), F' = 2, 3 with 1 MHz level accuracy. The optical feedback signal is generated from the narrow-band Faraday anomalous dispersion optical filter (FADOF) with nonlinear saturation effect. The peak transmission of the narrow-band FADOF corresponding to 5(2)S(1/2), F = 2 → 5(2)P(3/2), F' = 2, 3 crossover transition is 18.6 %. The bandwidth is as wide as 38.9 MHz as the laser frequency changes. After locking, the laser frequency fluctuation is reduced to 1.7 MHz. The all-optical laser locking technique can be improved to much higher accuracy with increased external cavity length. The laser we have realized can provide light exactly resonant with atomic transitions used for other atom-light interaction experiments.

  14. Cost Minimization Model of Gas Transmission Line for Indonesian SIJ Pipeline Network

    Directory of Open Access Journals (Sweden)

    Septoratno Siregar

    2003-05-01

    Full Text Available Optimization of Indonesian SIJ gas pipeline network is being discussed here. Optimum pipe diameters together with the corresponding pressure distribution are obtained from minimization of total cost function consisting of investment and operating costs and subjects to some physical (Panhandle A and Panhandle B equations constraints. Iteration technique based on Generalized Steepest-Descent and fourth order Runge-Kutta method are used here. The resulting diameters from this continuous optimization are then rounded to the closest available discrete sizes. We have also calculated toll fee along each segment and safety factor of the network by determining the pipe wall thickness, using ANSI B31.8 standard. Sensitivity analysis of toll fee for variation of flow rates is shown here. The result will gives the diameter and compressor size and compressor location that feasible to use for the SIJ pipeline project. The Result also indicates that the east route cost relatively less expensive than the west cost.

  15. Negative Flash for Calculating the Intersecting Key Tie lines in Multicomponent Gas Injection

    DEFF Research Database (Denmark)

    Yan, Wei; Michelsen, Michael Locht; Stenby, Erling Halfdan

    2014-01-01

    to the initial oil where all the intersecting key tielines must be identified. Calculation of these intersecting tielines requires a series of special negative flashes, which allow not only phase fractions outside the physical interval [0,1] but also negative feed compositions. The phase compositions from one...... negative flash are used to recombine the feed for the next negative flash. Despite the apparent complexity due to multicomponent phase equilibrium and transport, for pure component gas injection, negative flash and elimination of components can be performed in an alternating manner. In particular, if K......-values are constant, there exists a simple feature that the vapor fraction roots (beta-roots) for the RachfordRice equation for the initial oil are the roots to be found in all the negative flashes involved. This leads to a simple and well-structured algorithm for the solution with constant K-values. A special...

  16. Selection of the optimal combination of water vapor absorption lines for detection of temperature in combustion zones of mixing supersonic gas flows by diode laser absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mironenko V.R.

    2017-01-01

    Full Text Available Determination of a gas medium temperature by diode laser absorption spectrometry (DLAS is based on the measurement of integral intensities of the absorption lines of a test molecule (generally water vapor molecule. In case of local thermodynamic equilibrium temperature is inferred from the ratio of the integral intensities of two lines with different low energy levels. For the total gas pressure above 1 atm the absorption lines are broadened and one cannot find isolated well resolved water vapor absorption lines within relatively narrow spectral interval of fast diode laser (DL tuning range (about 3 cm−1. For diagnostics of a gas object in the case of high temperature and pressure DLAS technique can be realized with two diode lasers working in different spectral regions with strong absorption lines. In such situation the criteria of the optimal line selection differs significantly from the case of narrow lines. These criteria are discussed in our work. The software for selection the optimal spectral regions using the HITRAN-2012 and HITEMP data bases is developed. The program selects spectral regions of DL tuning, minimizing the error of temperature determination δТ/T, basing on the attainable experimental error of line intensity measurement δS. Two combinations of optimal spectral regions were selected – (1.392 & 1.343 μm and (1.392 & 1.339 μm. Different algorithms of experimental data processing are discussed.

  17. On-line quality monitoring in short-circuit gas metal arc welding

    Energy Technology Data Exchange (ETDEWEB)

    Adolfsson, S. [Univ. of Karlskrono/Ronneby (Sweden). Dept. of Signal Processing]|[Lund Univ. (Sweden). Dept. of Production and Materials Engineering; Bahrami, A. [Technology Center of Kronoberg, Vaexjoe (Sweden)]|[Lund Univ. (Sweden); Bolmsjoe, G. [Lund Univ. (Sweden); Claesson, I. [Univ. of Karlskrono/Ronneby (Sweden)

    1999-02-01

    This paper addresses the problems involved in the automatic monitoring of the weld quality produced by robotized short-arc welding. A simple statistical change detection algorithm for the weld quality, the repeated Sequential Probability Ratio Test (SPRT), was used. The algorithm may similarly be viewed as a cumulative sum (CUSUM) type test, and is well-suited to detecting sudden minor changes in the monitored test statistic. The test statistic is based on the variance of the weld voltage, wherein it will be shown that the variance decreases when the welding process is not operating under optimal conditions. The performance of the algorithm is assessed through the use of experimental data. The results obtained from the algorithm show that it is possible to detect changes in weld quality automatically and on-line.

  18. Development Of An Acoustice Sensor For On-Line Gas Temperature Measurement In Gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    Peter Ariessohn; Hans Hornung

    2006-10-01

    This project was awarded under U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) Program Solicitation DE-PS26-02NT41422 and specifically addresses Technical Topical Area 2 - Gasification Technologies. The project team includes Enertechnix, Inc. as the main contractor and ConocoPhillips Company as a technical partner, who also provides access to the SG Solutions Gasification Facility (formerly Wabash River Energy Limited), host for the field-testing portion of the research. The objective of this project was to adapt acoustic pyrometer technology to make it suitable for measuring gas temperature inside a coal gasifier, to develop a prototype sensor based on this technology, and to demonstrate its performance through testing on a commercial gasifier. The project was organized in three phases, each of approximately one year duration. The first phase consisted of researching a variety of sound generation and coupling approaches suitable for use with a high pressure process, evaluation of the impact of gas composition variability on the acoustic temperature measurement approach, evaluation of the impact of suspended particles and gas properties on sound attenuation, evaluation of slagging issues and development of concepts to deal with this issue, development and testing of key prototype components to allow selection of the best approaches, and development of a conceptual design for a field prototype sensor that could be tested on an operating gasifier. The second phase consisted of designing and fabricating a series of prototype sensors, testing them in the laboratory, and developing a conceptual design for a field prototype sensor. The third phase consisted of designing and fabricating the field prototype, and testing it in the lab and in a commercial gasifier to demonstrate the ability to obtain accurate measurements of gas temperature in an operating gasifier. This report describes all of the activities conducted during the project and

  19. Development of an Acoustic Sensor On-Line Gas Temperature Measurement in Gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    Peter Ariessohn

    2008-06-30

    This project was awarded under U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) Program Solicitation DE-PS26-02NT41422 and specifically addresses Technical Topical Area 2 - Gasification Technologies. The project team includes Enertechnix, Inc. as the main contractor and ConocoPhillips Company as a technical partner, who also provides access to the SG Solutions Gasification Facility (formerly Wabash River Energy Limited), host for the field-testing portion of the research. The objective of this project was to adapt acoustic pyrometer technology to make it suitable for measuring gas temperature inside a coal gasifier, to develop a prototype sensor based on this technology, and to demonstrate its performance through testing on a commercial gasifier. The project was organized in three phases, each of approximately one year duration. The first phase consisted of researching a variety of sound generation and coupling approaches suitable for use with a high pressure process, evaluation of the impact of gas composition variability on the acoustic temperature measurement approach, evaluation of the impact of suspended particles and gas properties on sound attenuation, evaluation of slagging issues and development of concepts to deal with this issue, development and testing of key prototype components to allow selection of the best approaches, and development of a conceptual design for a field prototype sensor that could be tested on an operating gasifier. The second phase consisted of designing and fabricating a series of prototype sensors, testing them in the laboratory, and developing a conceptual design for a field prototype sensor. The third phase consisted of designing and fabricating the field prototype, and testing it in the lab and in a commercial gasifier to demonstrate the ability to obtain accurate measurements of gas temperature in an operating gasifier. Following the completion of the initial 3 year project, several continuations

  20. VUV emission spectra from binary rare gas mixtures near the resonance lines of Xe I and Kr I

    CERN Document Server

    Morozov, A; Gerasimov, G; Arnesen, A; Hallin, R

    2003-01-01

    Emission spectra of Xe-X (X = He, Ne, Ar and Kr) and of Kr-Y (Y = He, Ne and Ar) mixtures with low concentrations of the heavier gases (0.1-1%) and moderate total pressures (50-200 hPa) have been recorded near each of the two resonance lines of Xe and Kr in DC glow capillary discharges. The recorded intense emissions have narrow spectral profiles with FWHM of about 0.1 nm. The profiles are very similar in shape to profiles of known high resolution absorption spectra recorded at comparable gas pressures. A tentative identification of the emission structures is given, which involves transitions in heteronuclear molecules and quasimolecules between weakly-bound states.

  1. Enhanced sensitivity of Raman spectroscopy for tritium gas analysis using a metal-lined hollow glass fiber

    Energy Technology Data Exchange (ETDEWEB)

    Rupp, S.; Schloesser, M.; Bornschein, B. [Institute of Technical Physics, Tritium Laboratory Karlsruhe, Karlsruhe Institute of Technology - KIT, Karlsruhe (Germany); James, T.M.; Telle, H.H. [Department of Physics, Swansea University, Swansea (United Kingdom)

    2015-03-15

    The precise compositional analysis of tritium-containing gases is of high interest for tritium accountancy in future fusion power plants. Raman spectroscopy provides a fast and contact-free gas analysis procedure with high precision, thus being an advantageous tool for the named purpose. In this paper, it is shown that the sensitivity achieved with conventional Raman systems (in 90 degrees or forward/backward configurations) can be enhanced by at least one order of magnitude by using a metal-lined hollow glass fiber as the Raman cell. This leads to the ability of detecting low partial pressures of tritium within short measurement intervals (< 0.5 mbar in < 0.5 s) opening the way for real-time applications.

  2. Mid-Infrared Atomic Fine-Structure Emission Line Spectra of Luminous Infrared Galaxies: Spitzer/IRS Spectra of the GOALS Sample

    CERN Document Server

    Inami, H; Charmandaris, V; Groves, B; Kewley, L; Petric, A; Stierwalt, S; Díaz-Santos, T; Surace, J; Rich, J; Haan, S; Howell, J; Evans, A; Mazzarella, J; Marshall, J; Appleton, P; Lord, S; Spoon, H; Frayer, D; Matsuhara, H; Veilleux, S

    2013-01-01

    We present the data and our analysis of MIR fine-structure emission lines detected in Spitzer/IRS high-res spectra of 202 local LIRGs observed as part of the GOALS project. We detect emission lines of [SIV], [NeII], [NeV], [NeIII], [SIII]18.7, [OIV], [FeII], [SIII]33.5, and [SiII]. Over 75% of our galaxies are classified as starburst (SB) sources in the MIR. We compare ratios of the emission line fluxes to stellar photo- and shock-ionization models to constrain the gas properties in the SB nuclei. Comparing the [SIV]/[NeII] and [NeIII]/[NeII] ratios to the Starburst99-Mappings III models with an instantaneous burst history, the line ratios suggest that the SB in our LIRGs have ages of 1-4.5Myr, metallicities of 1-2Z_sun, and ionization parameters of 2-8e7cm/s. Based on the [SIII]/[SIII] ratios, the electron density in LIRG nuclei has a median electron density of ~300cm-3 for sources above the low density limit. We also find that strong shocks are likely present in 10 SB sources. A significant fraction of the ...

  3. Kinetics and mechanism of the gas-phase reaction of Cl atoms and OH radicals with fluorobenzene at 296 K

    DEFF Research Database (Denmark)

    Andersen, Mads Peter Sulbæk; Nielsen, Ole John; Hurley, MD;

    2002-01-01

    constant for the reaction of C6H5F with Cl atoms. The equilibrium between Cl atoms, C6H5F, and the C6H5F-Cl adduct is established rapidly and has an equilibrium constant estimated to be K-5b=[C6H5F]/[Cl]/[C6H5F][Cl] = (3.2 +/- 2.4) x 10(-1)8 cm(3) molecule(-1). An upper limit of k(9)

  4. The Far-Infrared Emission Line and Continuum Spectrum of the Seyfert Galaxy NGC 1068

    Science.gov (United States)

    2005-04-10

    THE FAR-INFRARED EMISSION LINE AND CONTINUUM SPECTRUM OF THE SEYFERT GALAXY NGC 10681 Luigi Spinoglio Istituto di Fisica dello Spazio Interplanetario...circumnuclear ring of 1500–1600 in radius within the last 4–40 Myr. CO interferometer observa- tions revealed molecular gas very close to the nucleus...from 43 to 197 m showing both atomic and molecular emission lines (x 2). We model the composite UV to far-IR atomic emission-line and continuum

  5. The Star Formation Rate Efficiency of Neutral Atomic-dominated Hydrogen Gas in the Outskirts of Star Forming Galaxies from z~1 to z~3

    CERN Document Server

    Rafelski, Marc; Fumagalli, Michele; Neeleman, Marcel; Teplitz, Harry I; Grogin, Norman; Koekemoer, Anton M; Scarlata, Claudia

    2016-01-01

    Current observational evidence suggests that the star formation rate (SFR) efficiency of neutral atomic hydrogen gas measured in Damped Ly-alpha Systems (DLAs) at z~3 is more than 10 times lower than predicted by the Kennicutt-Schmidt (KS) relation. To understand the origin of this deficit, and to investigate possible evolution with redshift and galaxy properties, we measure the SFR efficiency of atomic gas at z~1, z~2, and z~3 around star-forming galaxies. We use new robust photometric redshifts in the Hubble Ultra Deep Field to create galaxy stacks in these three redshift bins, and measure the SFR efficiency by combining DLA absorber statistics with the observed rest-frame UV emission in the galaxies' outskirts. We find that the SFR efficiency of HI gas at z>1 is ~1-3% of that predicted by the KS relation. Contrary to simulations and models that predict a reduced SFR efficiency with decreasing metallicity and thus with increasing redshift, we find no significant evolution in the SFR efficiency with redshift...

  6. A high precision gas flow cell for performing in situ neutron studies of local atomic structure in catalytic materials

    Science.gov (United States)

    Olds, Daniel; Page, Katharine; Paecklar, Arnold; Peterson, Peter F.; Liu, Jue; Rucker, Gerald; Ruiz-Rodriguez, Mariano; Olsen, Michael; Pawel, Michelle; Overbury, Steven H.; Neilson, James R.

    2017-03-01

    Gas-solid interfaces enable a multitude of industrial processes, including heterogeneous catalysis; however, there are few methods available for studying the structure of this interface under operating conditions. Here, we present a new sample environment for interrogating materials under gas-flow conditions using time-of-flight neutron scattering under both constant and pulse probe gas flow. Outlined are descriptions of the gas flow cell and a commissioning example using the adsorption of N2 by Ca-exchanged zeolite-X (Na78-2xCaxAl78Si144O384,x ≈ 38). We demonstrate sensitivities to lattice contraction and N2 adsorption sites in the structure, with both static gas loading and gas flow. A steady-state isotope transient kinetic analysis of N2 adsorption measured simultaneously with mass spectrometry is also demonstrated. In the experiment, the gas flow through a plugged-flow gas-solid contactor is switched between 15N2 and 14N2 isotopes at a temperature of 300 K and a constant pressure of 1 atm; the gas flow and mass spectrum are correlated with the structure factor determined from event-based neutron total scattering. Available flow conditions, sample considerations, and future applications are discussed.

  7. First-principles DFT+U investigation of charged states of defects and fission gas atoms in CeO2

    Science.gov (United States)

    Shi, Lei; Vathonne, Emerson; Oison, Vincent; Freyss, Michel; Hayn, Roland

    2016-09-01

    Cerium dioxide (CeO2) is considered as a model material for the experimental study of radiation damage in the standard nuclear fuel uranium dioxide (UO2). In this paper, we present a first-principles study in the framework of the DFT+U approach to investigate the charged point defects and the incorporation of the fission gases Xe and Kr in CeO2 and compare it with published data in UO2. All intrinsic charge states are considered for point defects in contrast to previous published studies. Our calculations prove that CeO2 shows similar behavior to UO2 in the formation of point defects with the same charge states under stoichiometric and nonstoichiometric conditions. The charge states of vacancies have an important effect on the incorporation of fission gas atoms in CeO2. The bound Schottky defect with the two oxygen vacancies along the (100) direction is found to be energetically preferable to trap Xe and Kr atoms both in CeO2 and UO2. Xe and Kr atoms in the cation vacancy sites under nonformal charge states (different from 4 - ) in CeO2, unlike in UO2, lose electrons to their neighboring atoms, which is traced back to the absence of the +5 valence state for Ce in contrast to its existence for U.

  8. P-MaNGA Galaxies: Emission Lines Properties - Gas Ionisation and Chemical Abundances from Prototype Observations

    CERN Document Server

    Belfiore, F; Bundy, K; Thomas, D; Maraston, C; Wilkinson, D; Sánchez, S F; Bershady, M; Blanc, G A; Bothwell, M; Cales, S L; Coccato, L; Drory, N; Emsellem, E; Fu, H; Gelfand, J; Law, D; Masters, K; Parejko, J; Tremonti, C; Wake, D; Weijmans, A; Yan, R; Xiao, T; Zhang, K; Zheng, T; Bizyaev, D; Kinemuchi, K; Oravetz, D; Simmons, A

    2014-01-01

    MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a SDSS-IV survey that will obtain spatially resolved spectroscopy from 3600 \\AA\\ to 10300 \\AA\\ for a representative sample of over 10000 nearby galaxies. In this paper we present the analysis of nebular emission line properties using observations of 14 galaxies obtained with P-MaNGA, a prototype of the MaNGA instrument. By using spatially resolved diagnostic diagrams we find extended star formation in galaxies that are centrally dominated by Seyfert/LINER-like emission, illustrating that galaxy characterisations based on single fibre spectra are necessarily incomplete. We observe extended (up to $\\rm 1 R_{e}$) LINER-like emission in the central regions of three galaxies. We make use of the $\\rm EW(H \\alpha)$ to argue that the observed emission is consistent with ionisation from hot evolved stars. Using stellar population indices we conclude that galactic regions which are ionised by a Seyfert/LINER-like radiation field are also devoid of recent st...

  9. A fence line noble gas monitoring system for nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Grasty, R.L.; Hovgaard, J.; LaMarre, J.R

    2001-07-01

    A noble gas monitoring system has been installed at Ontario Power Generations' Pickering Nuclear Generating Station (PNGS) near Toronto, Canada. This monitoring system allows a direct measure of air kerma from external radiation instead of calculating this based on plant emission data and meteorological models. This has resulted in a reduction in the reported effective dose from external radiation by a factor of at least ten. The system consists of nine self-contained units, each with a 7.6 cm x 7.6 cm (3 inch x 3 inch) NaI(Tl) detector that is calibrated for air kerma. The 512-channel gamma ray spectral information is downloaded daily from each unit to a central computer where the data are stored and processed. A spectral stripping procedure is used to remove natural background variations from the spectral windows used to monitor xenon-133 ({sup 133}Xe), xenon-135 ({sup 135}Xe), argon-41 ({sup 41}Ar), and skyshine radiation from the use of radiography sources. Typical monthly minimum detection limits in air kerma are 0.3 nGy for {sup 133}Xe, 0.7 nGy for {sup 135}Xe, 3 nGy for {sup 41}Ar and 2 nGy for skyshine radiation. Based on 9 months of continuous operation, the annualised air kerma due to {sup 133}Xe, {sup 135}Xe and {sup 41}Ar and skyshine radiation were 7 nGy, 8 nGy, 26 nGy and 107 nGy respectively. (author)

  10. P-MaNGA Galaxies: emission-lines properties - gas ionization and chemical abundances from prototype observations

    Science.gov (United States)

    Belfiore, F.; Maiolino, R.; Bundy, K.; Thomas, D.; Maraston, C.; Wilkinson, D.; Sánchez, S. F.; Bershady, M.; Blanc, G. A.; Bothwell, M.; Cales, S. L.; Coccato, L.; Drory, N.; Emsellem, E.; Fu, H.; Gelfand, J.; Law, D.; Masters, K.; Parejko, J.; Tremonti, C.; Wake, D.; Weijmans, A.; Yan, R.; Xiao, T.; Zhang, K.; Zheng, T.; Bizyaev, D.; Kinemuchi, K.; Oravetz, D.; Simmons, A.

    2015-05-01

    MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a 6-yr Sloan Digital Sky Survey (SDSS-IV) survey that will obtain spatially resolved spectroscopy from 3600 to 10 300 Å for a representative sample of over 10 000 nearby galaxies. In this paper, we present the analysis of nebular emission-line properties using observations of 14 galaxies obtained with P-MaNGA, a prototype of the MaNGA instrument. By using spatially resolved diagnostic diagrams, we find extended star formation in galaxies that are centrally dominated by Seyfert/LINER-like emission, which illustrates that galaxy characterizations based on single fibre spectra are necessarily incomplete. We observe extended low ionization nuclear emission-line regions (LINER)-like emission (up to 1Re) in the central regions of three galaxies. We make use of the Hα equivalent width [EW(Hα)] to argue that the observed emission is consistent with ionization from hot evolved stars. We derive stellar population indices and demonstrate a clear correlation between Dn(4000) and EW(HδA) and the position in the ionization diagnostic diagram: resolved galactic regions which are ionized by a Seyfert/LINER-like radiation field are also devoid of recent star formation and host older and/or more metal-rich stellar populations. We also detect extraplanar LINER-like emission in two highly inclined galaxies, and identify it with diffuse ionized gas. We investigate spatially resolved metallicities and find a positive correlation between metallicity and star formation rate surface density. We further study the relation between N/O versus O/H on resolved scales. We find that, at given N/O, regions within individual galaxies are spread towards lower metallicities, deviating from the sequence defined by galactic central regions as traced by Sloan 3-arcsec fibre spectra. We suggest that the observed dispersion can be a tracer for gas flows in galaxies: infalls of pristine gas and/or the effect of a galactic fountain.

  11. Absorption spectroscopy of heavy alkaline earth metals Ba and Sr in rare gas matrices—CCSD(T) calculations and atomic site occupancies

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Barry M.; McCaffrey, John G., E-mail: john.mccaffrey@nuim.ie [Department of Chemistry, Maynooth University, National University of Ireland—Maynooth, County Kildare (Ireland)

    2016-01-28

    Isolation of the heavier alkaline earth metals Ba and Sr in the solid rare gases (RGs) Ar, Kr, and Xe is analysed with absorption spectroscopy and interpreted partly with the assistance of ab initio calculations of the diatomic M ⋅ RG ground state interaction potentials. The y{sup 1}P←a{sup 1}S resonance transitions in the visible spectral region are used to compare the isolation conditions of these two metal atom systems and calcium. Complex absorption bands were recorded in all three metal atom systems even after extensive sample annealing. Coupled cluster calculations conducted on the ground states of the nine M ⋅ RG diatomics (M = Ca, Sr, and Ba; RG = Ar, Kr, and Xe) at the coupled cluster single, double, and non-iterative triple level of theory revealed long bond lengths (>5 Å) and shallow bound regions (<130 cm{sup −1}). All of the M ⋅ RG diatomics have bond lengths considerably longer than those of the rare gas dimers, with the consequence that isolation of these metal atoms in a single substitutional site of the solid rare gas is unlikely, with the possible exception of Ca/Xe. The luminescence of metal dimer bands has been recorded for Ba and Sr revealing very different behaviours. Resonance fluorescence with a lifetime of 15 ns is observed for the lowest energy transition of Sr{sub 2} while this transition is quenched in Ba{sub 2}. This behaviour is consistent with the absence of vibrational structure on the dimer absorption band in Ba{sub 2} indicating lifetime broadening arising from efficient relaxation to low-lying molecular states. More extensive 2D excitation-emission data recorded for the complex site structures present on the absorption bands of the atomic Ba and Sr systems will be presented in future publications.

  12. Chemical substances injection in wells through the gas-lift line: state of the art; Injecao de produtos quimicos em pocos atraves de linha de gas-lift: estado-da-arte

    Energy Technology Data Exchange (ETDEWEB)

    Ramalho, Joao Batista Vianey da Silva [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas. Setor de Tecnologia de Producao, Processamento e Transporte]. E-mail: jramalho@cenpes.petrobras.com.br

    2000-12-01

    Injecting chemical substances on the subsurface in order to control incrustation, corrosion, emulsion and waxes, among other problems caused by the production at the oil wells, has not been used much because of the way they are usually injected. Recently, these products have been injected in wells through the gas-lift line, thus allowing control over the individual treatment in each well. The main conclusions arrived at with the reports made are the following: it is possible to inject chemical substances through the gas-lift line. The formulations of such products must be specific and they must contain the proper amounts of solvent to prevent the segregation of active matter. These products must be injected individually in the gas-lift line at each well. (author)

  13. On the atomization and combustion of liquid biofuels in gas turbines: towards the application of biomass-derived pyrolysis oil

    NARCIS (Netherlands)

    Sallevelt, Johan Leonard Hendrik Pieter

    2015-01-01

    The combustion of liquid biofuels in gas turbines is an efficient way of generating heat and power from biomass. Gas turbines play a major role in the global energy supply and are suitable for a wide range of applications. However, biofuels generally have different properties compared to conventiona

  14. Simultaneous assessment of cholesterol absorption and synthesis in humans using on-line gas chromatography/ combustion and gas chromatography/pyrolysis/isotope-ratio mass spectrometry.

    Science.gov (United States)

    Gremaud, G; Piguet, C; Baumgartner, M; Pouteau, E; Decarli, B; Berger, A; Fay, L B

    2001-01-01

    A number of dietary components and drugs are known to inhibit the absorption of dietary and biliary cholesterol, but at the same time can compensate by increasing cholesterol synthesis. It is, therefore, necessary to have a convenient and accurate method to assess both parameters simultaneously. Hence, we validated such a method in humans using on-line gas chromatography(GC)/combustion and GC/pyrolysis/isotope-ratio mass spectrometry (IRMS). Cholesterol absorption was measured using the ratio of [(13)C]cholesterol (injected intravenously) to [(18)O]cholesterol (administered orally). Simultaneously, cholesterol synthesis was measured using the deuterium incorporation method. Our methodology was applied to 12 mildly hypercholesterolemic men that were given a diet providing 2685 +/- 178 Kcal/day (mean +/- SD) and 255 +/- 8 mg cholesterol per day. Cholesterol fractional synthesis rates ranged from 5.0 to 10.5% pool/day and averaged 7.36% +/- 1.78% pool/day (668 +/- 133 mg/day). Cholesterol absorption ranged from 36.5-79.9% with an average value of 50.8 +/- 15.4%. These values are in agreement with already known data obtained with mildly hypercholesterolemic Caucasian males placed on a diet similar to the one used for this study. However, our combined IRMS method has the advantage over existing methods that it enables simultaneous measurement of cholesterol absorption and synthesis in humans, and is therefore an important research tool for studying the impact of dietary treatments on cholesterol parameters.

  15. Sapphire: a better material for atomization and in situ collection of silver volatile species for atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Musil, Stanislav, E-mail: stanomusil@biomed.cas.cz; Matoušek, Tomáš; Dědina, Jiří

    2015-06-01

    Sapphire is presented as a high temperature and corrosion resistant material of an optical tube of an atomizer for volatile species of Ag generated by the reaction with NaBH{sub 4}. The modular atomizer design was employed which allowed to carry out the measurements in two modes: (i) on-line atomization and (ii) in situ collection (directly in the optical tube) by means of excess of O{sub 2} over H{sub 2} in the carrier gas during the trapping step and vice versa in the volatilization step. In comparison with quartz atomizers, the sapphire tube atomizer provides a significantly increased atomizer lifetime as well as substantially improved repeatability of the Ag in situ collection signals shapes. In situ collection of Ag in the sapphire tube atomizer was highly efficient (> 90%). Limit of detection in the on-line atomization mode and in situ collection mode, respectively, was 1.2 ng ml{sup −1} and 0.15 ng ml{sup −1}. - Highlights: • Sapphire was tested as a new material of an atomizer tube for Ag volatile species. • Two measurement modes were investigated: on-line atomization and in situ collection. • In situ collection of Ag was highly efficient (> 90%) with LOD of 0.15 ng ml{sup −1}. • No devitrification of the sapphire tube observed in the course of several months.

  16. Rapid determination of butyltin species in water samples by multicapillary gas chromatography with atomic emission detection following headspace solid-phase microextraction.

    Science.gov (United States)

    Botana, J Carpinterio; Pereiro, I Rodríguez; Torrijos, R Cela

    2002-07-19

    A procedure for the rapid determination of mono-, di- and tributyltin in water samples is described. The analytes are simultaneously ethylated and concentrated on a solid-phase microextraction fibre placed in the headspace over the sample for 2 min. The ethylated species are then separated and selectively quantified in only 90 s using a multicapillary gas chromatography column combined with atomic emission detection. The influence of blank signals and sampling conditions on the sensitivity of the method is described. Detection limits of 1-5 ng/l and relative standard deviations of 6-10% at concentrations of 20 ng/l were obtained.

  17. Dithiocarbamate functionalized or surface sorbed Merrifield resin beads as column materials for on line flow injection-flame atomic absorption spectrometry determination of lead.

    Science.gov (United States)

    Praveen, R S; Naidu, G R K; Prasada Rao, T

    2007-09-26

    This article describes the preparation of dithiocarbamate immobilized/functionalized and diethylammonium dithiocarbamate (DDTC) sorbed Merrifield Chloromethylated Resin (MCR) beads and comparison of these materials for on-line flow injection (FI)-flame atomic absorption spectrometry (FAAS) determination of lead. The above two materials enrich lead quantitatively over an identical optimal pH range (8.0-9.0), a preconcentration/loading time (up to 4 min) and elution with acidified methanol (a minimum of 0.01 molL(-1) HNO(3) in methanol). However, the detection limit for lead using dithiocarbamate functionalized MCR beads is 1.3 microgL(-1) compared to 3 microgL(-1) for DDTC sorbed MCR beads. Again, the sensitivity enhancement over direct FAAS signal is 48- and 27-fold, respectively. In addition, dithiocarbamate functionalized MCR beads offers better precision compared to DDTC sorbed MCR beads as the corresponding relative standard deviation (R.S.D.) values for five successive determinations of 0.20 microgmL(-1) are 1.44 and 4.36%, respectively. The accuracy of the developed on-line FI-FAAS procedure employing dithiocarbamate functionalized MCR beads as column material was tested by analyzing Certified Reference Material (CRM) of soil (IAEA soil-7) and marine sediment reference material (MESS-3) supplied by International Atomic Energy Agency (IAEA), Vienna and National Research Council (NRC), Canada, respectively. Furthermore, the developed procedure has been successfully tested for the analysis of surface, pond, ground and effluent water and soil samples collected from the vicinity of lead acid battery industry in India.

  18. Methods of Soft Tissue Emulsification Using a Mechanism of Ultrasonic Atomization Inside Gas or Vapor Cavities and Associated Systems and Devices

    Science.gov (United States)

    Sapozhnikov, Oleg A. (Inventor); Bailey, Michael R. (Inventor); Crum, Lawrence A. (Inventor); Khokhlova, Tatiana D. (Inventor); Khokhlova, Vera A. (Inventor); Simon, Julianna C. (Inventor); Wang, Yak-Nam (Inventor)

    2016-01-01

    The present technology is directed to methods of soft tissue emulsification using a mechanism of ultrasonic atomization inside gas or vapor cavities, and associated systems and devices. In several embodiments, for example, a method of non-invasively treating tissue includes pulsing ultrasound energy from the ultrasound source toward the target site in tissue. The ultrasound source is configured to emit high intensity focused ultrasound (HIFU) waves. The target site comprises a pressure-release interface of a gas or vapor cavity located within the tissue. The method continues by generating shock waves in the tissue to induce a lesion in the tissue at the target site. The method additionally includes characterizing the lesion based on a degree of at least one of a mechanical or thermal ablation of the tissue.

  19. Collisions of halogen (/sup 2/P) and rare gas (/sup 1/S) atoms. [Differential cross sections, elastic model, coupling potential energy, L-S coupling, multiplets

    Energy Technology Data Exchange (ETDEWEB)

    Becker, C.H.

    1978-12-01

    Differential cross sections I (THETA) at several collision energies measured in crossed molecular beam experiments are reported for several combinations of halogen atoms (/sup 2/P) scattered off rare gas-rare gas atoms (/sup 1/S/sub 0/), namely, F + Ne, F + Ar, F + Kr, F + Xe, C1 + Xe. The scattering is described by an elastic model appropriate to Hund's case c coupling. With the use of this model, the X 1/2, I 3/2, and II 1/2 interaction potential energy curves are derived by fitting calculated differential cross sections, based on analytic representations of the potentials, to the data. The F - Xe X 1/2 potential shows a significant bonding qualitatively different than for the other F-rare gases. The I 3/2 and II 1/2 potentials closely resemble the van der Waals interactions of the one electron richer ground state rare gas-rare gas systems. Coupled-channel scattering calculations are carried out for F + Ar, F + Xe, and C1 + Xe using the realistic potential curves derived earlier. The results justify the use of the elastic model, and give additional information on intramultiplet and intermultiplet transitions. The transitions are found to be governed by the crossing of the two ..cap omega.. = 1/2 potentials in the complex plane. The measured I (theta) and I (THETA) derived from the coupled-channel computations show small oscillations or perturbations (Stueckelberg oscillations) though quantitative agreement is not obtained.The nature of the anomalous F - Xe X 1/2 potential is discussed as is the approximation of a constant spin orbit coupling over the experimentally accessible range of internuclear distances for these open shell molecules. 55 references.

  20. Automatic On-line Solid-phase Extraction-Electrothermal Atomic Absorption Spectrometry Exploiting Sequential Injection Analysis for Trace Vanadium, Cadmium and Lead Determination in Human Urine Samples.

    Science.gov (United States)

    Giakisikli, Georgia; Ayala Quezada, Alejandro; Tanaka, Junpei; Anthemidis, Aristidis N; Murakami, Hiroya; Teshima, Norio; Sakai, Tadao

    2015-01-01

    A fully automated sequential injection column preconcentration method for the on-line determination of trace vanadium, cadmium and lead in urine samples was successfully developed, utilizing electrothermal atomic absorption spectrometry (ETAAS). Polyamino-polycarboxylic acid chelating resin (Nobias chelate PA-1) packed into a handmade minicolumn was used as a sorbent material. Effective on-line retention of chelate complexes of analytes was achieved at pH 6.0, while the highest elution effectiveness was observed with 1.0 mol L(-1) HNO3 in the reverse phase. Several analytical parameters, like the sample acidity, concentration and volume of the eluent as well as the loading/elution flow rates, have been studied, regarding the efficiency of the method, providing appropriate conditions for the analysis of real samples. For a 4.5 mL sample volume, the sampling frequency was 27 h(-1). The detection limits were found to be 3.0, 0.06 and 2.0 ng L(-1) for V(V), Cd(II) and Pb(II), respectively, with the relative standard deviations ranging between 1.9 - 3.7%. The accuracy of the proposed method was evaluated by analyzing a certified reference material (Seronorm(TM) trace elements urine) and spiked urine samples.

  1. Application of water drainage and gas recovery by ultrasonic atomization technology in Daniudi gas field%超声雾化排水系统采气工艺在大牛地气田的应用

    Institute of Scientific and Technical Information of China (English)

    姜志超

    2016-01-01

    大牛地气田位于陕蒙交界处,是我国重要的天然气产区。天然气井在产气的同时普遍产水,对天然气的质量和气井的正常生产都产生严重影响。本文主要介绍超声雾化排水采气工艺的原理及在大牛地气田的应用。%This paper mainly discusses the principle of ultrasonic atomization technology and its application in Daniudi gas field.

  2. Interface for time-resolved introduction of gaseous analytes for atomic spectrometry by purge-and-trap multicapillary gas chromatography (PTMGC)

    Science.gov (United States)

    Wasik, Andrzej; Rodriguez Pereiro, Isaac; Łobiński, Ryszard

    1998-08-01

    A semi-automated compact interface that enables time-resolved introduction of gaseous analytes from aqueous solutions into an atomic spectrometer without the need for a full-size GC-oven is described. The interface is based on purging the gaseous analytes with an inert gas, drying the gas stream using a 30-cm tubular Nafion membrane and trapping the compounds in a thick film-coated capillary tube followed by their isothermal separation on a 1-m multicapillary GC column. Developments regarding each of the steps of the analytical procedure and effects of operational variables (sample volume, purge flow, trap temperature, speed of injection, GC separation conditions) are discussed using the speciation analysis of a mixture of tetraalkyllead compounds as an example. Recoveries are quantitative up to a sample volume of 50 ml. Figures of merit for the interface coupled to a microwave-induced plasma atomic emission detector are given. The interface allows the full speciation analysis (including sample preparation) to be carried out within less than 5 min with detection limits down to 5 pg l -1.

  3. Studies on Microstructure and Thermoelectric Properties of p-Type Bi-Sb-Te Based Alloys by Gas Atomization and Hot Extrusion Processes

    Science.gov (United States)

    Park, Ki-Chan; Madavali, Babu; Kim, Eun-Bin; Koo, Kyung-Wan; Hong, Soon-Jik

    2016-10-01

    p-Type Bi2Te3 + 75% Sb2Te3 based thermoelectric materials were fabricated via gas atomization and the hot extrusion process. The gas atomized powder showed a clean surface with a spherical shape, and expanded in a wide particle size distribution (average particle size 50 μm). The phase of the fabricated extruded and R-extruded bars was identified using x-ray diffraction. The relative densities of both the extruded and R-extruded samples were measured by Archimedes principle with ˜98% relative density. The R-extruded bar exhibited finer grain microstructure than that of single extrusion process, which was attributed to a recrystallization mechanism during the fabrication. The R-extruded sample showed improved Vickers hardness compared to the extruded sample due to its fine grain microstructure. The electrical conductivity improved for the extruded sample whereas the Seebeck coefficient decreases due to its high carrier concentration. The peak power factor, ˜4.26 × 10-3 w/mK2 was obtained for the single extrusion sample, which is higher than the R-extrusion sample owing to its high electrical properties.

  4. A data acquisition system for two-dimensional position sensitive micropattern gas detectors with delay-line readout

    Energy Technology Data Exchange (ETDEWEB)

    Hanu, A.R., E-mail: hanua@mcmaster.ca [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, Canada L8S 4K1 (Canada); NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Prestwich, W.V.; Byun, S.H. [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, Canada L8S 4K1 (Canada)

    2015-04-21

    We present a data acquisition (DAQ) system for two-dimensional position sensitive micropattern gas detectors using the delay-line method for readout. The DAQ system consists of a field programmable gate array (FPGA) as the main data processor and our time-to-digital (TDC) mezzanine card for making time measurements. We developed the TDC mezzanine card around the Acam TDC-GPX ASIC and it features four independent stop channels referenced to a common start, a typical timing resolution of ~81 ps, and a 17-bit measurement range, and is compliant with the VITA 57.1 standard. For our DAQ system, we have chosen the Xilinx SP601 development kit which features a single Spartan 6 FPGA, 128 MB of DDR2 memory, and a serial USB interface for communication. Output images consist of 1024×1024 square pixels, where each pixel has a 32-bit depth and corresponds to a time difference of 162 ps relative to its neighbours. When configured for a 250 ns acquisition window, the DAQ can resolve periodic event rates up to 1.8×10{sup 6} Hz without any loses and will report a maximum event rate of 6.11×10{sup 5} Hz for events whose arrival times follow Poisson statistics. The integral and differential non-linearities have also been measured and are better than 0.1% and 1.5%, respectively. Unlike commercial units, our DAQ system implements the delay-line image reconstruction algorithm entirely in hardware and is particularly attractive for its modularity, low cost, ease of integration, excellent linearity, and high throughput rate.

  5. Sequential injection on-line matrix removal and trace metal preconcentration using a PTFE beads packed column as demonstrated for the determination of cadmium by electrothermal atomic absorption spectrometry

    DEFF Research Database (Denmark)

    Wang, Jianhua; Hansen, Elo Harald

    2002-01-01

    A sequential injection (SI) on-line matrix removal and trace metal preconcentration procedure by using a novel microcolumn packed with PTFE beads is described, and demonstrated for trace cadmium analysis with detection by electrothermal atomic absorption spectrometry (ETAAS). The analyte is initi......A sequential injection (SI) on-line matrix removal and trace metal preconcentration procedure by using a novel microcolumn packed with PTFE beads is described, and demonstrated for trace cadmium analysis with detection by electrothermal atomic absorption spectrometry (ETAAS). The analyte...

  6. On-line sequential injection dispersive liquid-liquid microextraction system for flame atomic absorption spectrometric determination of copper and lead in water samples.

    Science.gov (United States)

    Anthemidis, Aristidis N; Ioannou, Kallirroy-Ioanna G

    2009-06-30

    A simple, sensitive and powerful on-line sequential injection (SI) dispersive liquid-liquid microextraction (DLLME) system was developed as an alternative approach for on-line metal preconcentration and separation, using extraction solvent at microlitre volume. The potentials of this novel schema, coupled to flame atomic absorption spectrometry (FAAS), were demonstrated for trace copper and lead determination in water samples. The stream of methanol (disperser solvent) containing 2.0% (v/v) xylene (extraction solvent) and 0.3% (m/v) ammonium diethyldithiophosphate (chelating agent) was merged on-line with the stream of sample (aqueous phase), resulting a cloudy mixture, which was consisted of fine droplets of the extraction solvent dispersed entirely into the aqueous phase. By this continuous process, metal chelating complexes were formed and extracted into the fine droplets of the extraction solvent. The hydrophobic droplets of organic phase were retained into a microcolumn packed with PTFE-turnings. A portion of 300 microL isobutylmethylketone was used for quantitative elution of the analytes, which transported directly to the nebulizer of FAAS. All the critical parameters of the system such as type of extraction solvent, flow-rate of disperser and sample, extraction time as well as the chemical parameters were studied. Under the optimum conditions the enhancement factor for copper and lead was 560 and 265, respectively. For copper, the detection limit and the precision (R.S.D.) were 0.04 microg L(-1) and 2.1% at 2.0 microg L(-1) Cu(II), respectively, while for lead were 0.54 microg L(-1) and 1.9% at 30.0 microg L(-1) Pb(II), respectively. The developed method was evaluated by analyzing certified reference material and applied successfully to the analysis of environmental water samples.

  7. The complex, dusty narrow-line region of NGC 4388: Gas-jet interactions, outflows, and extinction revealed by near-IR spectroscopy

    CERN Document Server

    Rodriguez-Ardila, A; Martins, L; Almeida, C Ramos; Riffel, R A; Riffel, R; Lira, P; Martin, O Gonzalez; Dametto, N Z; Flohic, H; Ho, L C; Ruschel-Dutra, D; Thanjavur, K; Colina, L; McDermid, R M; Perlman, E; Winge, C

    2016-01-01

    We present Gemini/GNIRS spectroscopy of the Seyfert 2 galaxy NGC 4388, with simultaneous coverage from 0.85 - 2.5 $\\mu$m. Several spatially-extended emission lines are detected for the first time, both in the obscured and unobscured portion of the optical narrow line region (NLR), allowing us to assess the combined effects of the central continuum source, outflowing gas and shocks generated by the radio jet on the central 280 pc gas. The HI and [FeII] lines allow us to map the extinction affecting the NLR. We found that the nuclear region is heavily obscured, with E(B-V) ~1.9 mag. To the NE of the nucleus and up to ~150 pc, the extinction remains large, ~1 mag or larger, consistent with the system of dust lanes seen in optical imaging. We derived position-velocity diagrams for the most prominent lines as well as for the stellar component. Only the molecular gas and the stellar component display a well-organized pattern consistent with disk rotation. Other emission lines are kinematically perturbed or show lit...

  8. Cooling of Dense Gas by H2O Line Emission and an Assessment of its Effects in Chondrule-Forming Shocks

    CERN Document Server

    Morris, M A; Ciesla, F J

    2008-01-01

    We consider gas at densities appropriate to protoplanetary disks and calculate its ability to cool due to line radiation emitted by H2O molecules within the gas. Our work follows that of Neufeld & Kaufman (1993; ApJ, 418, 263), expanding on their work in several key aspects, including use of a much expanded line database, an improved escape probability formulism, and the inclusion of dust grains, which can absorb line photons. Although the escape probabilities formally depend on a complicated combination of optical depth in the lines and in the dust grains, we show that the cooling rate including dust is well approximated by the dust-free cooling rate multiplied by a simple function of the dust optical depth. We apply the resultant cooling rate of a dust-gas mixture to the case of a solar nebula shock pertinent to the formation of chondrules, millimeter-sized melt droplets found in meteorites. Our aim is to assess whether line cooling can be neglected in chondrule-forming shocks or if it must be included....

  9. Ejecta Particle-Size Measurements in Vacuum and Helium Gas using Ultraviolet In-Line Fraunhofer Holography

    Energy Technology Data Exchange (ETDEWEB)

    Sorenson, D. S. [LANL; Pazuchanics, P. [LANL; Johnson, R. [LANL; Malone, R. M. [NSTec; Kaufman, M. I. [NSTec; Tibbitts, A. [NSTec; Tunnell, T. [NSTec; Marks, D. [NSTec; Capelle, G. A. [NSTec; Grover, M. [NSTec; Marshall, B. [NSTec; Stevens, G. D. [NSTec; Turley, W. D. [NSTec; LaLone, B. [NSTec

    2014-06-30

    An ultraviolet (UV) in-line Fraunhofer holography diagnostic has been developed for making high-resolution spatial measurements of ejecta particles traveling at many mm/μsec. This report will discuss the development of the diagnostic, including the high-powered laser system and high-resolution optical relay system. In addition, we will also describe the system required to reconstruct the images from the hologram and the corresponding analysis of those images to extract particles. Finally, we will present results from six high-explosive (HE), shock-driven Sn-ejecta experiments. Particle-size distributions will be shown that cover most of the ejecta velocities for experiments conducted in a vacuum, and helium gas environments. In addition, a modification has been made to the laser system that produces two laser pulses separated by 6.8 ns. This double-pulsed capability allows a superposition of two holograms to be acquired at two different times, thus allowing ejecta velocities to be measured directly. Results from this double-pulsed experiment will be described.

  10. Ejecta Particle-Size Measurements in Vacuum and Helium Gas using Ultraviolet In-Line Fraunhofer Holography

    Energy Technology Data Exchange (ETDEWEB)

    Sorenson, Danny S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pazuchanics, Peter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Johnson, Randall P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Malone, R. M. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Kaufman, M. I. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Tibbitts, A. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Tunnell, T. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Marks, D. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Capelle, G. A. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Grover, M. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Marshall, B. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Stevens, G. D. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Turley, W. D. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); LaLone, B. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States)

    2014-06-25

    An Ultraviolet (UV) in-line Fraunhofer holography diagnostic has been developed for making high-resolution spatial measurements of ejecta particles traveling at many mm/μsec. This report will discuss the development of the diagnostic including the high-powered laser system and high-resolution optical relay system. In addition, the system required to reconstruct the images from the hologram and the corresponding analysis of those images to extract particles will also be described. Finally, results from six high-explosive (HE), shock-driven Sn ejecta experiments will be presented. Particle size distributions will be shown that cover most of the ejecta velocities for experiments conducted in a vacuum, and helium gas environments. In addition, a modification has been made to the laser system that produces two laser pulses separated by 6.8 ns. This double-pulsed capability allows a superposition of two holograms to be acquired at two different times, thus allowing ejecta velocities to be measured directly. Results from this double pulsed experiment will be described.

  11. Ejecta Particle-Size Measurements in Vacuum and Helium Gas using Ultraviolet In-Line Fraunhofer Holography

    Energy Technology Data Exchange (ETDEWEB)

    Sorenson, D. S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pazuchanics, P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Johnson, R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Malone, R. M. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Kaufman, M. I. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Tibbitts, A. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Tunnell, T. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Marks, D. [National Security Technologies, LLC. (NSTec), Los Alamos, NM (United States); Capelle, G. A. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Grover, M. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Marshall, B. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Stevens, G. D. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); Turley, W. D. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States); LaLone, B. [National Security Technologies, LLC. (NSTec), Santa Barbara, CA (United States)

    2014-06-01

    An ultraviolet (UV) in-line Fraunhofer holography diagnostic has been developed for making high-resolution spatial measurements of ejecta particles traveling at many mm/μsec. This report will discuss the development of the diagnostic, including the high-powered laser system and high-resolution optical relay system. In addition, we will also describe the system required to reconstruct the images from the hologram and the corresponding analysis of those images to extract particles. Finally, we will present results from six high-explosive (HE), shock-driven Sn-ejecta experiments. Particle-size distributions will be shown that cover most of the ejecta velocities for experiments conducted in a vacuum, and helium gas environments. In addition, a modification has been made to the laser system that produces two laser pulses separated by 6.8 ns. This double-pulsed capability allows a superposition of two holograms to be acquired at two different times, thus allowing ejecta velocities to be measured directly. Results from this double-pulsed experiment will be described.

  12. Modeling and Simulation of the Microstructure Evolution of the Gas-atomized Alloy Droplets during Spray Forming

    Institute of Scientific and Technical Information of China (English)

    Jiuzhou ZHAO; Dongming LIU; Hengqiang YE

    2003-01-01

    In order to understand the solidification process of an atomized droplet and predict the fraction solidification ofdroplets with flight distance during spray forming, a numerical model based on the population dynamics approach isdeveloped to describe the microstructure evolution under the common action of the nucleation and growth of grains.The model is coupled with droplets heat transfer controlling equations and solved for Al-4.5 wt pct Cu alloy. It isdemonstrated that the numerical results describe the solidification process well.

  13. Kinetic of the gas-phase reactions of OH radicals and Cl atoms with Diethyl Ethylphosphonate and Triethyl Phosphate

    KAUST Repository

    Laversin, H.

    2015-11-30

    In this paper, the relative-rate technique has been used to obtain rate coefficients for the reaction of two organophosphorus compounds: Triethyl phosphate (TEP) and Diethyl ethylphosphonate (DEEP) with OH radicals and Cl atoms at atmospheric pressure and at different temperatures. The calculated rate constants were fitted to the Arrhenius expression over the temperature range 298 – 352 K. The following expressions (in cm3molecule-1s-1) were obtained for the reactions of OH and CL with DEEP and TEP: kOH+DEEP= (7.84±0.65)x10-14exp((1866±824)/T), kOH+TEP = (6.54±0.42)x10-14exp((1897±626)/T), kCl+DEEP = (5.27± 0.80)x10−11exp(765±140/T) and kCl+TEP = (5.23± 0.80)x10−11exp(736± 110/T). These results show that the reaction of the studied compounds with Cl atoms proceeds more rapidly than that with OH radicals. The related tropospheric lifetimes suggest that once emitted into the atmosphere, TEP and DEEP can be removed within a few hours in areas close to their emission sources. TEP and DEEP are principally removed by OH radicals. However, in coastal areas where the Cl atoms’ concentration is higher, TEP and DEEP removal by reaction with Cl atoms could be a competitive process.

  14. The complex, dusty narrow-line region of NGC 4388: gas-jet interactions, outflows and extinction revealed by near-IR spectroscopy

    Science.gov (United States)

    Rodríguez-Ardila, A.; Mason, R. E.; Martins, L.; Ramos Almeida, C.; Riffel, R. A.; Riffel, R.; Lira, P.; González Martín, O.; Dametto, N. Z.; Flohic, H.; Ho, L. C.; Ruschel-Dutra, D.; Thanjavur, K.; Colina, L.; McDermid, R. M.; Perlman, E.; Winge, C.

    2017-02-01

    We present Gemini/GNIRS (Gemini Near-Infrared Spectrograph) spectroscopy of the Seyfert 2 galaxy NGC 4388, with simultaneous coverage from 0.85 to 2.5 μm. Several spatially extended emission lines are detected for the first time, both in the obscured and unobscured portion of the optical narrow-line region (NLR), allowing us to assess the combined effects of the central continuum source, outflowing gas and shocks generated by the radio jet on the central 280 pc gas. The H I and [Fe II] lines allow us to map the extinction affecting the NLR. We found that the nuclear region is heavily obscured, with E(B - V) ˜ 1.9 mag. To the NE of the nucleus and up to ˜150 pc, the extinction remains large, ˜1 mag or larger, consistent with the system of dust lanes seen in optical imaging. We derived position-velocity diagrams for the most prominent lines as well as for the stellar component. Only the molecular gas and the stellar component display a well-organized pattern consistent with disc rotation. Other emission lines are kinematically perturbed or show little evidence of rotation. Extended high-ionization emission of sulphur, silicon and calcium is observed to distances of at least 200 pc both NE and SW of the nucleus. We compared flux ratios between these lines with photoionization models and conclude that radiation from the central source alone cannot explain the observed high-ionization spectrum. Shocks between the radio jet and the ambient gas are very likely an additional source of excitation. We conclude that NGC 4388 is a prime laboratory to study the interplay between all these mechanisms.

  15. Quantitation of toxic arsenic species and arsenobetaine in Pacific oysters using an off-line process with hydride generation-atomic absorption spectroscopy.

    Science.gov (United States)

    Hsiung, Tung-Ming; Huang, Chia-Wei

    2006-04-05

    An off-line process-based speciation technique was devised here to quantitatively determine toxic inorganic arsenic (iAs), methylarsonic acid (MA), dimethylarsinic acid (DMA), and the dominant, albeit virtually nontoxic, arsenobetaine (AB) in Pacific oysters (Crassostrea gigas). Oysters were extracted with fresh methanol-water (8+2), and this was replicated three times. They were then evaporated to near dryness and subsequently redissolved in pure water; defatting was then performed with a C18 cartridge. The trace hydride active arsenic species, that is, iAs, MA, and DMA, in the defatted solutions were determined with a sensitive hydride generation-packed coldfinger trap-atomic absorption spectrometric (HG-PCFT-AAS) coupled system. The arsenicals that were desorbed from the cation-exchange resin (Dowex 50W-X8) in the washings of 4 M NH3 were categorized on the basis of AB + DMA. The total quantity of arsenic in the recovered AB + DMA was determined with a commercial hydride generation-atomic absorption spectrometric (HG-AAS) system, and finally, AB was calculated from (AB + DMA) - DMA. The average concentrations of iAs, MA, DMA, AB, and total arsenic (TAs) in the oysters collected from six aquacultural sites along the west coast of Taiwan were, respectively, 0.15, 0.06, 0.64, 6.93, and 13.74 mg kg(-1) of dry weight. AB was the major species, whereas iAs (arsenite + arsenate) were the most toxic species, although the iAs made up only approximately 1% of the TAs in the oysters. The lifetime target cancer risk, as determined by the concentration of iAs on a fresh weight basis in the oysters, was well below the ordinary health protection criteria (10(-6)).

  16. The origin of the near-IR line emission from molecular, low and high ionization gas in the inner kiloparsec of NGC6240

    CERN Document Server

    Ilha, Gabriele S; Riffel, R A

    2016-01-01

    The understating of the origin of the H2 line emission from the central regions of galaxies represent an important key to improve our knowledge about the excitation and ionization conditions of the gas in these locations. Usually these lines can be produced by Starburts, shocks and/or radiation from an active galactic nucleus (AGN). Luminous Infrared Galaxies (LIRG) represent ideal and challenging objects to investigate the origin of the H2 emission, as all processes above can be observed in a single object. In this work, we use K-band integral field spectroscopy to map the emission line flux distributions and kinematics and investigate the origin of the molecular and ionized gas line emission from inner 1.4x2.4 kpc2 of the LIRG NGC6240, known to be the galaxy with strongest H2 line emission. The emission lines show complex profiles at locations between both nuclei and surrounding the northern nucleus, while at locations near the southern nucleus and at 1" west of the northern nucleus, they can be reproduced ...

  17. Determination of Hg{sup 2+} by on-line separation and pre-concentration with atmospheric-pressure solution-cathode glow discharge atomic emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qing [Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 200050 (China); Zhang, Zhen [Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 200050 (China); School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Wang, Zheng, E-mail: wangzheng@mail.sic.ac.cn [Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 200050 (China)

    2014-10-03

    Highlights: • A modified SBA-15 mesoporous silica (SH-SBA-15) was synthesized as a sorbent. • On-line SPE combined with SCGD-AES based on FIA was used to detect Hg{sup 2+} firstly. • A simple, low-cost Hg{sup 2+} analysis in a complex matrix was established. • The sensitive detection of Hg{sup 2+} was achieved with a detection limit of 0.75 μg L{sup −1}. - Abstract: A simple and sensitive method to determine Hg{sup 2+} was developed by combining solution-cathode glow discharge atomic emission spectrometry (SCGD-AES) with flow injection (FI) based on on-line solid-phase extraction (SPE). We synthesized L-cysteine-modified mesoporous silica and packed it in an SPE microcolumn, which was experimentally determined to possess a good mercury adsorption capacity. An enrichment factor of 42 was achieved under optimized Hg{sup 2+} elution conditions, namely, an FI flow rate of 2.0 mL min{sup −1} and an eluent comprised of 10% thiourea in 0.2 mol L{sup −1} HNO{sub 3}. The detection limit of FI–SCGD-AES was determined to be 0.75 μg L{sup −1}, and the precision of the 11 replicate Hg{sup 2+} measurements was 0.86% at a concentration of 100 μg L{sup −1}. The proposed method was validated by determining Hg{sup 2+} in certified reference materials such as human hair (GBW09101b) and stream sediment (GBW07310)

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

    CERN Document Server

    Loreau, J; Dalgarno, A

    2013-01-01

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

  19. Separation of seven arsenic compounds by high-performance liquid chromatography with on-line detection by hydrogen–argon flame atomic absorption spectrometry and inductively coupled plasma mass spectrometry

    DEFF Research Database (Denmark)

    Hansen, S. H.; Larsen, E. H.; Pritzl, G.

    1992-01-01

    Seven molecular forms of arsenic were separated by anion- and cation-exchange high-performance liquid chromatography (HPLC) with on-line detection by flame atomic absorption spectrometry (FAAS). The interfacing was established by a vented poly(tetrafluoroethylene) capillary tubing connecting...... the HPLC column to the nebulizer of the atomic absorption spectrometer. Arsenite, arsenate, monomethylarsonate (MMA) and dimethylarsinate (DMA) were separated from each other and from the co-injected cationic arsenic compounds, arsenobetaine (AsB), arsenocholine (AsC) and the tetramethylarsonium ion (TMAs......-to-noise ratio of the on-line AAS detector was optimized. This involved the use of the hydrogen-argon-entrained air flame, a slotted tube atom trap in the flame for signal enhancement, electronic noise damping and a high-intensity light source. The detection limits in mu-g cm-3, using 100 mm3 injections...

  20. Separation of seven arsenic compounds by high performance liquid chromatography with on-line detection by hydrogen-argon flame atomic absorption spectrometry and inductively coupled plasma mass spectrometry

    DEFF Research Database (Denmark)

    Hansen, S. H.; Larsen, Erik Huusfeldt; Pritzl, G.

    1992-01-01

    Seven molecular forms of arsenic were separated by anion- and cation-exchange high-performance liquid chromatography (HPLC) with on-line detection by flame atomic absorption spectrometry (FAAS). The interfacing was established by a vented poly(tetrafluoroethylene) capillary tubing connecting...... the HPLC column to the nebulizer of the atomic absorption spectrometer. Arsenite, arsenate, monomethylarsonate (MMA) and dimethylarsinate (DMA) were separated from each other and from the co-injected cationic arsenic compounds, arsenobetaine (AsB), arsenocholine (AsC) and the tetramethylarsonium ion (TMAs......-to-noise ratio of the on-line AAS detector was optimized. This involved the use of the hydrogen-argon-entrained air flame, a slotted tube atom trap in the flame for signal enhancement, electronic noise damping and a high-intensity light source. The detection limits in mu-g cm-3, using 100 mm3 injections...