WorldWideScience

Sample records for atomic hydrogen gas

  1. 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.

  2. Observation of nuclear spin waves in spin-polarized atomic hydrogen gas

    Energy Technology Data Exchange (ETDEWEB)

    Johson, B.R.; Denker, J.S.; Bigelow, N.; Levy, L.P.; Freed, J.H.; Lee, D.M.

    1984-04-23

    We have observed narrow, distinct resonances in the NMR spectrum of dilute spin-polarized atomic hydrogen gas (nroughly-equal10/sup 16/ atoms/cm/sup 3/). The dependence of the observed spectra on temperature, density, polarization, and magnetic field gradient is consistent with theoretical predictions for spin-wave excitations damped by diffusion. We have measured the parameter ..mu.., which is a measure of the importance of exchange effects in spin transport processes, and the diffusion coefficient D/sub 0/, both of which are in reasonable agreement with theory.

  3. Hyperfine frequency shift of atomic hydrogen in the presence of helium buffer gas

    Energy Technology Data Exchange (ETDEWEB)

    Jochemsen, R.; Berlinsky, A.J. (British Columbia Univ., Vancouver (Canada). Dept. of Physics)

    1982-02-01

    A quantum mechanical thermal average is performed to obtain the temperature dependence of the hyperfine frequency shift (HFS) of hydrogen atoms in the presence of He buffer gas. The calculations are based on existing ab initio calculations of the hyperfine frequency shift as a function of internuclear separation and of the interatomic potential. We find that the HFS changes sign at fairly low temperature and has a small negative value at T = 1 K in agreement with recent measurements. The overall temperature dependence is shown to be quite sensitive to the interatomic potential.

  4. Measuring deuterium enrichment of glucose hydrogen atoms by gas chromatography/mass spectrometry.

    Science.gov (United States)

    Antoniewicz, Maciek R; Kelleher, Joanne K; Stephanopoulos, Gregory

    2011-04-15

    We developed a simple and accurate method for determining deuterium enrichment of glucose hydrogen atoms by electron impact gas chromatography mass spectrometry (GC/MS). First, we prepared 18 derivatives of glucose and screened over 200 glucose fragments to evaluate the accuracy and precision of mass isotopomer data for each fragment. We identified three glucose derivatives that gave six analytically useful ions: (1) glucose aldonitrile pentapropionate (m/z 173 derived from C4-C5 bond cleavage; m/z 259 from C3-C4 cleavage; m/z 284 from C4-C5 cleavage; and m/z 370 from C5-C6 cleavage); (2) glucose 1,2,5,6-di-isopropylidene propionate (m/z 301, no cleavage of glucose carbon atoms); and (3) glucose methyloxime pentapropionate (m/z 145 from C2-C3 cleavage). Deuterium enrichment at each carbon position of glucose was determined by least-squares regression of mass isotopomer distributions. The validity of the approach was tested using labeled glucose standards and carefully prepared mixtures of standards. Our method determines deuterium enrichment of glucose hydrogen atoms with an accuracy of 0.3 mol %, or better, without the use of any calibration curves or correction factors. The analysis requires only 20 μL of plasma, which makes the method applicable for studying gluconeogenesis using deuterated water in cell culture and animal experiments. © 2011 American Chemical Society

  5. Diffusion cross section for atomic hydrogen in helium gas at low temperature and the H-He potential

    Energy Technology Data Exchange (ETDEWEB)

    Jochemsen, R.; Berlinsky, A.J.; Hardy, W.N. (British Columbia Univ., Vancouver (Canada). Dept. of Physics)

    1984-08-01

    A calculation of the diffusion cross section Q sub(D) of hydrogen atoms in helium gas at low temperature is performed and compared with recent experimental results. The comparison allows an improved determination of the H-He potential. Calculations were done for three different potentials: our own empirical potential based on experimental high-energy scattering results and calculated long-range dispersion terms, which gives good results for Q sub(D) and total collision cross sections; a recently determined semi-empirical potential, and an ab initio calculated potential. All three potentials imply a strong temperature dependence of Q sub(D) for T < 1.5 K.

  6. Sampling the Hydrogen Atom

    Directory of Open Access Journals (Sweden)

    Graves N.

    2013-01-01

    Full Text Available A model is proposed for the hydrogen atom in which the electron is an objectively real particle orbiting at very near to light speed. The model is based on the postulate that certain velocity terms associated with orbiting bodies can be considered as being af- fected by relativity. This leads to a model for the atom in which the stable electron orbits are associated with orbital velocities where Gamma is n /α , leading to the idea that it is Gamma that is quantized and not angular momentum as in the Bohr and other models. The model provides a mechanism which leads to quantization of energy levels within the atom and also provides a simple mechanical explanation for the Fine Struc- ture Constant. The mechanism is closely associated with the Sampling theorem and the related phenomenon of aliasing developed in the mid-20th century by engineers at Bell labs.

  7. Hydrogen rich gas generator

    Science.gov (United States)

    Houseman, J. (Inventor)

    1976-01-01

    A process and apparatus is described for producing a hydrogen rich gas by introducing a liquid hydrocarbon fuel in the form of a spray into a partial oxidation region and mixing with a mixture of steam and air that is preheated by indirect heat exchange with the formed hydrogen rich gas, igniting the hydrocarbon fuel spray mixed with the preheated mixture of steam and air within the partial oxidation region to form a hydrogen rich gas.

  8. 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...

  9. Kinetic theory of weakly ionized dilute gas of hydrogen-like atoms of the first principles of quantum statistics and dispersion laws of eigenwaves

    Science.gov (United States)

    Slyusarenko, Yurii V.; Sliusarenko, Oleksii Yu.

    2017-11-01

    We develop a microscopic approach to the construction of the kinetic theory of dilute weakly ionized gas of hydrogen-like atoms. The approach is based on the statements of the second quantization method in the presence of bound states of particles. The basis of the derivation of kinetic equations is the method of reduced description of relaxation processes. Within the framework of the proposed approach, a system of common kinetic equations for the Wigner distribution functions of free oppositely charged fermions of two kinds (electrons and cores) and their bound states—hydrogen-like atoms— is obtained. Kinetic equations are used to study the spectra of elementary excitations in the system when all its components are non-degenerate. It is shown that in such a system, in addition to the typical plasma waves, there are longitudinal waves of matter polarization and the transverse ones with a behavior characteristic of plasmon polaritons. The expressions for the dependence of the frequencies and Landau damping coefficients on the wave vector for all branches of the oscillations discovered are obtained. Numerical evaluation of the elementary perturbation parameters in the system on an example of a weakly ionized dilute gas of the 23Na atoms using the D2-line characteristics of the natrium atom is given. We note the possibility of using the results of the developed theory to describe the properties of a Bose condensate of photons in the diluted weakly ionized gas of hydrogen-like atoms.

  10. The Star Formation Rate Efficiency of Neutral Atomic-Dominated Hydrogen Gas in the Ooutskirts of Star-Forming Galaxies From z approx. 1 to z approx. 3

    Science.gov (United States)

    Rafelski, Marc; Gardner, Jonathan P.; 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 approx. 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 approx. 1, z approx. 2, and z approx. 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 H I gas at z > 1 is approx. 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. Our analysis instead suggests that the reduced SFR efficiency is driven by the low molecular content of this atomic-dominated phase, with metallicity playing a secondary effect in regulating the conversion between atomic and molecular gas. This interpretation is supported by the similarity between the observed SFR efficiency and that observed in local atomic-dominated gas, such as in the outskirts of local spiral galaxies and local dwarf galaxies.

  11. Hydrogen gas detector card

    Directory of Open Access Journals (Sweden)

    Francisco Sánchez Niño

    2016-04-01

    Full Text Available A small card used for detecting hydrogen gas in a crystal growth system by the liquid phase epitaxy technique was designed and built. The small size of the card enables its portability to other laboratories where leakage detection of hydrogen or other flammable gas is required. Card dimensions are approximately 10 cm long and 5 cm wide enabling easy transportation. The design is based on a microcontroller which reads the signal from the hydrogen sensor and internally compares the read value with preset values. Depending on the signal voltage a red, yellow or green LED will light to indicate the levels of concentration of the flammable gas. The card is powered by a 9 V battery.

  12. Theory of low temperature spin exchange scattering for a physiosorbed two-dimensional gas of hydrogen atoms

    Energy Technology Data Exchange (ETDEWEB)

    Morrow, M.; Berlinsky, A.J.

    1983-07-01

    Calculations are presented of the two-dimensional scattering cross sections which are required to evaluate the longitudinal and transverse relaxation times T/sub 1/ and T/sub 2/ and the frequency shift ..delta..v due to spin exchange collision between H atoms physisorbed on a surface. The results are used to interpret the recent measurements by Crampton and co-workers of the relaxation time T/sub 1/ for H atoms in the presence of solid H/sub 2/ walls. New results are also presented for T/sub 1/, due to three-dimensional scattering in the gas, using a more recent triplet H-H potential than the one previously employed by Berlinsky and Shizgal.

  13. Hydrogen analysis in solid samples by utilizing He metastable atoms induced by TEA CO{sub 2} laser plasma in He gas at 1 atm

    Energy Technology Data Exchange (ETDEWEB)

    Ramli, Muliadi [Program of Nuclear Power and Energy Safety Engineering, Graduate School of Engineering, University of Fukui, Fukui 910-8507 (Japan); Idris, Nasrullah [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh, Aceh 23111 (Indonesia); Fukumoto, Kenichi; Niki, Hideaki [Program of Nuclear Power and Energy Safety Engineering, Graduate School of Engineering, University of Fukui, Fukui 910-8507 (Japan); Sakan, Fujio [Department of Material Science, Faculty of Engineering, University of Fukui, Fukui 910-8507 (Japan); Maruyama, Tadashi [Integrated Research Institute, Tokyo Institute of Technology, 4259 Nagatsuda-cho, Midori-ku Yokohama 226-8503 (Japan); Kurniawan, Koo Hendrik; Lie, Tjung Jie [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Kagawa, Kiichiro [Department of Physics, Faculty of Education and Regional Studies, University of Fukui (Japan)], E-mail: kagawa@edu00.f-edu.fukui-u.ac.jp

    2007-12-15

    A TEA CO{sub 2} laser (350 mJ-1.5 J, 10.6 {mu}m, 200 ns, 10 Hz) was focused onto a metal sub-target under He as host gas at 1 atmospheric pressure with a small amount of impurity gas, such as water and ethanol vapors. It was found that the TEA CO{sub 2} laser with the help of the metal sub-target is favorable for generating a strong, large volume helium gas breakdown plasma at 1 atmospheric pressure, in which the helium metastable-excited state was then produced overwhelmingly. While the metal sub-target itself was never ablated. The helium metastable-excited state produced after the strong helium gas breakdown plasma was considered to play an important role in exciting the atoms. This was confirmed by the specific characteristics of the detected H{alpha} emission, namely the strong intensity with low background, narrow spectral width, and the long lifetime. This technique can be used for gas and solid samples analysis. For nonmetal solid analysis, a metal mesh was introduced in front of the nonmetal sample surface to help initiation of the helium gas breakdown plasma. For metal sample, analysis can be carried out by combining the TEA CO{sub 2} laser and an Nd-YAG laser where the Nd-YAG laser is used to ablate the metal sample. The ablated atoms from the metal sample are then sent into the region of helium gas breakdown plasma induced by the TEA CO{sub 2} laser to be excited through the helium metastable-excited state. This technique can be extended to the analysis of other elements, not limited only to hydrogen, such as halogens.

  14. Scattering of muonic hydrogen atoms

    Energy Technology Data Exchange (ETDEWEB)

    Mulhauser, F. [Universite de Fribourg (Switzerland); Adamczak, A. [Institute of Nuclear Physics (Poland); Beer, G.A. [University of Victoria (Canada); Bystritsky, V.M. [Joint Institute for Nuclear Research (Russian Federation); Filipowicz, M. [Institute of Physics and Nuclear Techniques (Poland); Fujiwara, M.C. [University of British Columbia (Canada); Huber, T.M. [Gustavus Adolphus College (United States); Jacot-Guillarmod, R. [Universite de Fribourg (Switzerland); Kammel, P. [University of California (United States); Kim, S.K. [Jeonbuk National University (Korea, Republic of); Knowles, P. [Universite de Fribourg (Switzerland); Kunselman, A.R. [University of Wyoming (United States); Maier, M. [University of Victoria (Canada); Markushin, V.E. [Paul Scherrer Institute (Switzerland); Marshall, G.M. [TRIUMF (Canada); Olin, A. [University of Victoria (Canada); Petitjean, C. [Paul Scherrer Institute (Switzerland); Porcelli, T.A. [University of Victoria (Canada); Stolupin, V.A. [Joint Institute for Nuclear Research (Russian Federation); Wozniak, J. [Institute of Physics and Nuclear Techniques (Poland)] (and others)

    1999-06-15

    Our measurement compares the energy dependence of the scattering cross-sections of muonic deuterium and tritium on hydrogen molecules for collisions in the energy range 0.1-45 eV. A time-of-flight method was used to measure the scattering cross-section as a function of the muonic atom beam energy and shows clearly the Ramsauer-Townsend effect. The results are compared with theoretical calculations by using Monte Carlo simulations. The molecular pd{mu} and pt{mu} formation creates background processes. We measure the formation rates in solid hydrogen by detecting the 5.5 MeV (pd{mu}) and 19.8 MeV (pt{mu}) {gamma}-rays emitted during the subsequent nuclear fusion processes.

  15. Precision spectroscopy on atomic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Parthey, Christian Godehard

    2011-12-15

    This Thesis reports on three measurements involving the 1S-2S transition in atomic hydrogen and deuterium conducted on a 5.8 K atomic beam. The transition is excited Doppler-free via two counter-propagating photons near 243 nm. The H/D isotope shift has been determined as {delta}{integral}{sub exp}=670 994 334 606(15) Hz. Comparing with the theoretical value for the isotope shift, excluding the leading nuclear size effect, {delta}{integral}{sub th}=670 999 566.90(66)(60) kHz we confirm, twice more accurate, the rms charge radius difference of the deuteron and the proton as left angle r{sup 2} right angle {sub d}- left angle r{sup 2} right angle {sub p}=3.82007(65) fm{sup 2} and the deuteron structure radius r{sub str}=1.97507(78) fm. The frequency ratio of the 1S-2S transition in atomic hydrogen to the cesium ground state hyperfine transition provided by the mobile cesium fountain clock FOM is measured to be {integral}{sub 1S-2S}=2 466 061 413 187 035 (10) Hz which presents a fractional frequency uncertainty of 4.2 x 10{sup -15}. The second absolute frequency measurement of the 1S-2S transition in atomic hydrogen presents the first application of a 900 km fiber link between MPQ and Physikalisch- Technische Bundesanstalt (PTB) in Braunschweig which we have used to calibrate the MPQ hydrogen maser with the stationary cesium fountain clock CSF1 at PTB. With the result of {integral}{sub 1S-2S}=2 466 061 413 187 017 (11) Hz we can put a constraint on the electron Lorentz boost violating coefficients 0.95c{sub (TX)}-0.29c{sub (TY)}-0.08 c{sub (TZ)}=(2.2{+-}1.8) x 10{sup -11} within the framework of minimal standard model extensions. We limit a possible drift of the strong coupling constant through the ratio of magnetic moments at a competitive level ({partial_derivative})/({partial_derivative}t)ln ({mu}{sub Cs})/({mu}{sub B})=-(3.0{+-}1.2) x 10{sup -15} yr{sup -1}.

  16. Atomic hydrogen storage method and apparatus

    Science.gov (United States)

    Woollam, J. A. (Inventor)

    1980-01-01

    Atomic hydrogen, for use as a fuel or as an explosive, is stored in the presence of a strong magnetic field in exfoliated layered compounds such as molybdenum disulfide or an elemental layer material such as graphite. The compounds maintained at liquid helium temperatures and the atomic hydrogen is collected on the surfaces of the layered compound which are exposed during delamination (exfoliation). The strong magnetic field and the low temperature combine to prevent the atoms of hydrogen from recombining to form molecules.

  17. Use of atomic hydrogen source in collision: technological challenges

    Science.gov (United States)

    Hovey, R. T.; Vargas, E. L.; Panchenko, D. I.; Rivas, D. A.; Andrianarijaona, V. M.

    2015-03-01

    Atomic hydrogen was extensively studied in the past due to its obvious fundamental aspect. Also, quite few investigations were dedicated to atomic hydrogen sources because the results of experimental investigations on systems involving H would provide very rigorous tests for theoretical models. But even if atomic hydrogen sources are currently widespread in experimental physics, their uses in experiments on collisions are still very challenging mainly due to threefold problem. First, there is the difficulty to create H in the laboratory in sufficiently large number densities. Second, there is the strain to adjust the velocities of the produced atomic hydrogens. And third, there is the toil to control the internal energies of these atomic hydrogens. We will present an outline of different techniques using atomic hydrogen sources in collisions, which could be found in the literatures, such as merged-beam technique, gas cell technique, and trap, and propose an experiment scheme using a turn-key atomic hydrogen source that experiments such as charge transfer could benefit from. This work is supported by the National Science Foundation under Grant No. PHY-1068877.

  18. Muonium/muonic hydrogen formation in atomic hydrogen

    Indian Academy of Sciences (India)

    Abstract. The muonium/muonic hydrogen atom formation in µ±–H collisions is in- vestigated, using a two-state approximation in a time dependent formalism. It is found that muonium cross-section results are similar to the cross-section results obtained for positronium formation in e+–H collision. Muonic hydrogen atom ...

  19. Ionisation of atomic hydrogen by positron impact

    Science.gov (United States)

    Spicher, Gottfried; Olsson, Bjorn; Raith, Wilhelm; Sinapius, Guenther; Sperber, Wolfgang

    1990-01-01

    With the crossed beam apparatus the relative impact-ionization cross section of atomic hydrogen by positron impact was measured. A layout of the scattering region is given. The first measurements on the ionization of atomic hydrogen by positron impact are also given.

  20. Studies in Composing Hydrogen Atom Wavefunctions

    DEFF Research Database (Denmark)

    Putnam, Lance Jonathan; Kuchera-Morin, JoAnn; Peliti, Luca

    2015-01-01

    We present our studies in composing elementary wavefunctions of a hydrogen-like atom and identify several relationships between physical phenomena and musical composition that helped guide the process. The hydrogen-like atom accurately describes some of the fundamental quantum mechanical phenomen...

  1. Solid Hydrogen Particles and Flow Rates Analyzed for Atomic Fuels

    Science.gov (United States)

    Palaszewski, Bryan A.

    2003-01-01

    The experiments were conducted at Glenn's Small Multipurpose Research Facility (SMIRF, ref. 5). The experimental setup was placed in the facility's vacuum tank to prevent heat leaks and subsequent boiloff of the liquid helium. Supporting systems maintained the temperature and pressure of the liquid helium bath where the solid particles were created. Solid hydrogen particle formation was tested from February 23 to April 2, 2001. Millimeter-sized solid-hydrogen particles were formed in a Dewar of liquid helium as a prelude to creating atomic fuels and propellants for aerospace vehicles. Atomic fuels or propellants are created when atomic boron, carbon, or hydrogen is stored in solid hydrogen particles. The current testing characterized the solid hydrogen particles without the atomic species, as a first step to creating a feed system for the atomic fuels and propellants. This testing did not create atomic species, but only sought to understand the solid hydrogen particle formation and behavior in the liquid helium. In these tests, video images of the solid particle formation were recorded, and the total mass flow rate of the hydrogen was measured. The mass of hydrogen that went into the gaseous phase was also recorded using a commercially available residual gas analyzer. The temperatures, pressures, and flow rates of the liquids and gases in the test apparatus were recorded as well. Testing conducted in 1999 recorded particles as small as 2 to 5 mm in diameter. The current testing extended the testing conditions to a very cold Dewar ullage gas of about 20 to 90 K above the 4 K liquid helium. With the very cold Dewar gas, the hydrogen freezing process took on new dimensions, in some cases creating particles so small that they seemed to be microscopic, appearing as infinitesimally small scintillations on the videotaped images.

  2. Atomic hydrogen as a launch vehicle propellant

    Science.gov (United States)

    Palaszewski, Bryan A.

    1990-01-01

    An analysis of several atomic hydrogen launch vehicles was conducted. A discussion of the facilities and the technologies that would be needed for these vehicles is also presented. The Gross Liftoff Weights (GLOW) for two systems were estimated; their specific impulses (I sub sp) were 750 and 1500 lb(sub f)/s/lb(sub m). The atomic hydrogen launch vehicles were also compared to the currently planned Advanced Launch System design concepts. Very significant GLOW reductions of 52 to 58 percent are possible over the Advanced Launch System designs. Applying atomic hydrogen propellants to upper stages was also considered. Very high I(sub sp) (greater than 750 lb(sub f)/s/lb(sub m)) is needed to enable a mass savings over advanced oxygen/hydrogen propulsion. Associated with the potential benefits of high I(sub sp) atomic hydrogen are several challenging problems. Very high magnetic fields are required to maintain the atomic hydrogen in a solid hydrogen matrix. The magnetic field strength was estimated to be 30 kilogauss (3 Tesla). Also the storage temperature of the propellant is 4 K. This very low temperature will require a large refrigeration facility for the launch vehicle. The design considerations for a very high recombination rate for the propellant are also discussed. A recombination rate of 210 cm/s is predicted for atomic hydrogen. This high recombination rate can produce very high acceleration for the launch vehicle. Unique insulation or segmentation to inhibit the propellant may be needed to reduce its recombination rate.

  3. On the energy of electric field in hydrogen atom

    OpenAIRE

    Kornyushin, Yuri

    2009-01-01

    It is shown that hydrogen atom is a unique object in physics having negative energy of electric field, which is present in the atom. This refers also to some hydrogen-type atoms: hydrogen anti-atom, atom composed of proton and antiproton, and positronium.

  4. 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.

  5. Benchmarking Attosecond Physics with Atomic Hydrogen

    Science.gov (United States)

    2015-05-25

    Final 3. DATES COVERED (From - To) 12 Mar 12 – 11 Mar 15 4. TITLE AND SUBTITLE Benchmarking attosecond physics with atomic hydrogen 5a...AND SUBTITLE Benchmarking attosecond physics with atomic hydrogen 5a. CONTRACT NUMBER FA2386-12-1-4025 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Final Report for AOARD Grant FA2386-12-1-4025 “ Benchmarking

  6. From lattice gauge theories to hydrogen atoms

    Directory of Open Access Journals (Sweden)

    Manu Mathur

    2015-10-01

    Full Text Available We construct canonical transformations to obtain a complete and most economical realization of the physical Hilbert space Hp of pure SU(22+1 lattice gauge theory in terms of Wigner coupled Hilbert spaces of hydrogen atoms. One hydrogen atom is assigned to every plaquette of the lattice. A complete orthonormal description of the Wilson loop basis in Hp is obtained by all possible angular momentum Wigner couplings of hydrogen atom energy eigenstates |n l m〉 describing electric fluxes on the loops. The SU(2 gauge invariance implies that the total angular momenta of all hydrogen atoms vanish. The canonical transformations also enable us to rewrite the Kogut–Susskind Hamiltonian in terms of fundamental Wilson loop operators and their conjugate electric fields. The resulting loop Hamiltonian has a global SU(2 invariance and a simple weak coupling (g2→0 continuum limit. The canonical transformations leading to the loop Hamiltonian are valid for any SU(N. The ideas and techniques can also be extended to higher dimension.

  7. The role of final-state correlations in recombination of atomic hydrogen

    NARCIS (Netherlands)

    Stoof, H.T.C.; Goey, L.P.H. de; Verhaar, B.J.; Glöckle, W.

    1987-01-01

    We calculate the rate-constant for recombination in the bulk of a spin-polarized atomic hydrogen gas. We use an exact initial state and include the most essential collision aspects of the final state, except for rearrangement.

  8. Wave mechanics of the hydrogen atom

    OpenAIRE

    Ogilvie, J. F.

    2016-01-01

    The hydrogen atom is a system amenable to an exact treatment within Schroedinger's formulation of quantum mechanics according to coordinates in four systems -- spherical polar, paraboloidal, ellipsoidal and spheroconical coordinates; the latter solution is reported for the first time. Applications of these solutions include angular momenta, a quantitative calculation of the absorption spectrum and accurate plots of surfaces of amplitude functions. The shape of an amplitude function, and even ...

  9. Semiclassical treatment of laser excitation of the hydrogen atom

    DEFF Research Database (Denmark)

    Billing, Gert D.; Henriksen, Niels Engholm; Leforestier, C.

    1992-01-01

    We present an alternative method for studying excitation of atoms in intense laser fields. In the present paper we focus upon the optical harmonic generation by hydrogen atoms.......We present an alternative method for studying excitation of atoms in intense laser fields. In the present paper we focus upon the optical harmonic generation by hydrogen atoms....

  10. Solid Hydrogen Particles Analyzed for Atomic Fuels

    Science.gov (United States)

    Palaszewski, Bryan A.

    2001-01-01

    Solid hydrogen particles have been selected as a means of storing atomic propellants in future launch vehicles (refs. 1 to 2). In preparation for this, hydrogen particle formation in liquid helium was tested experimentally. These experiments were conducted to visually characterize the particles and to observe their formation and molecular transformations (aging) while in liquid helium. The particle sizes, molecular transformations, and agglomeration times were estimated from video image analyses. The experiments were conducted at the NASA Glenn Research Center in the Supplemental Multilayer Insulation Research Facility (SMIRF, ref. 3). The facility has a vacuum tank, into which the experimental setup was placed. The vacuum tank prevented heat leaks and subsequent boiloff of the liquid helium, and the supporting systems maintained the temperature and pressure of the liquid helium bath where the solid particles were created. As the operation of the apparatus was developed, the hydrogen particles were easily visualized. The figures (ref. 1) show images from the experimental runs. The first image shows the initial particle freezing, and the second image shows the particles after the small particles have agglomerated. The particles finally all clump, but stick together loosely. The solid particles tended to agglomerate within a maximum of 11 min, and the agglomerate was very weak. Because the hydrogen particles are buoyant in the helium, the agglomerate tends to compact itself into a flat pancake on the surface of the helium. This pancake agglomerate is easily broken apart by reducing the pressure above the liquid. The weak agglomerate implies that the particles can be used as a gelling agent for the liquid helium, as well as a storage medium for atomic boron, carbon, or hydrogen. The smallest particle sizes that resulted from the initial freezing experiments were about 1.8 mm. About 50 percent of the particles formed were between 1.8 to 4.6 mm in diameter. These very

  11. Removing hydrogen sulphide from a gas mixture

    Energy Technology Data Exchange (ETDEWEB)

    Christy, J.G.

    1990-07-31

    This invention relates, in particular, to removing hydrogen sulfide from a gas mixture in which the molar ratio of carbon dioxide to hydrogen sulfide is very large, for example between 20 and 45. Examples of such mixtures include natural gas or gas produced by coal gasification. According to the invention, the gas mixture is contacted in a main absorber at an elevated temperature with lean and regenerable aqueous absorbent to obtain a purified gas mixture and a loaded absorbent. The loaded absorbent is introduced into a separation vessel at a reduced pressure, and flash-off gas and partially regenerated absorbent are removed from the vessel. Hydrogen sulfide is removed from the flash-off gas to obtain a lean gas, and the removed hydrogen sulfide is converted into elemental sulfur. The partially regenerated absorbent is introduced into a regenerator to obtain lean absorbent for use in the first step, and a regenerator off-gas including hydrogen sulfide. The regenerator off-gas is supplied to a sulfur recovery plant to obtain elemental sulfur and a SO{sub 2}-containing off-gas. This off-gas is treated in a converter to obtain a reduced off-gas. At least part of the lean gas obtained in a previous step is mixed with the reduced plant off-gas, and the remainder is mixed with the plant off-gas. Hydrogen sulfide is removed from the mixture of reduced off-gas and lean gas to obtain substantially hydrogen sulfide-free off-gas; the removed hydrogen sulfide is converted into elemental sulfur. The absorbent used in this process includes a chemical absorbent, such as an amine, and a physical absorbent, such as sulfolane. 1 fig.

  12. Non-thermal hydrogen atoms in the terrestrial upper thermosphere.

    Science.gov (United States)

    Qin, Jianqi; Waldrop, Lara

    2016-12-06

    Model predictions of the distribution and dynamical transport of hydrogen atoms in the terrestrial atmosphere have long-standing discrepancies with ultraviolet remote sensing measurements, indicating likely deficiencies in conventional theories regarding this crucial atmospheric constituent. Here we report the existence of non-thermal hydrogen atoms that are much hotter than the ambient oxygen atoms in the upper thermosphere. Analysis of satellite measurements indicates that the upper thermospheric hydrogen temperature, more precisely the mean kinetic energy of the atomic hydrogen population, increases significantly with declining solar activity, contrary to contemporary understanding of thermospheric behaviour. The existence of hot hydrogen atoms in the upper thermosphere, which is the key to reconciling model predictions and observations, is likely a consequence of low atomic oxygen density leading to incomplete collisional thermalization of the hydrogen population following its kinetic energization through interactions with hot atomic or ionized constituents in the ionosphere, plasmasphere or magnetosphere.

  13. Magnetic resonance of atomic hydrogen at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, W.N.; Morrow, M.; Jochemsen, R.; Berlinsky, A.J. (British Columbia Univ., Vancouver (Canada). Dept. of Physics)

    1982-07-01

    This article reviews the present state of magnetic resonance studies of atomic hydrogen gas at low temperatures. The various types of resonances that can be exploited are discussed and the paper ends with a review of the existing experimental data. It will be seen that up to the present, essentially all of the results have been derived from pulsed magnetic resonance of the 1420 MHz zero field hyperfine transition, and the many interesting results expected of the high field experiments are yet to appear.

  14. Time-of-flight spectroscopy of muonic hydrogen atoms and molecules

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, M.C. [Dept. of Physics and Astronomy, Univ. of British Columbia, Vancouver, BC (Canada)]|[Dept. of Physics, Faculty of Science, Univ. of Tokyo (Japan); Adamczak, A. [Inst. of Nuclear Physics, Krakow (Poland); Bailey, J.M. [Chester Technology, Chester (United Kingdom); Beer, G.A.; Mason, G.R. [Dept. of Physics and Astronomy, Univ. of Victoria, BC (Canada); Beveridge, J.L.; Marshall, G.M.; Olin, A. [TRIUMF, Vancouver, BC (Canada); Faifman, M.P. [Russian Research Center, Kurchatov Inst., Moscow (Russian Federation); Huber, T.M. [Dept. of Physics, Gustavus Adolphus Coll., St. Peter, MN (United States); Kammel, P. [Dept. of Physics and Lawrence Berkeley National Lab., Univ. of California, Berkeley, CA (United States); Kim, S.K. [Dept. of Physics, Jeonbuk National Univ., Jeonju City (Korea); Knowles, P.E.; Mulhauser, F. [Inst. of Physics, Univ. of Fribourg (Switzerland); Kunselman, A.R. [Dept. of Physics and Astronomy, Univ. of Wyoming, Laramie, WY (United States); Markushin, V.E.; Petitjean, C. [Paul Scherrer Inst., Villigen (Switzerland); Porcelli, T.A. [Dept. of Physics, Univ. of Northern British Columbia, Prince George, BC (Canada); Zmeskal, J. [Inst. for Medium Energy Physics, Austrian Academy of Sciences, Vienna (Austria)

    2001-07-01

    Studies of muonic hydrogen atoms and molecules have been performed traditionally in bulk targets of gas, liquid or solid. At TRIUMF, Canada's meson facility, we have developed a new type of target system using multilayer thin films of solid hydrogen, which provides a beam of muonic hydrogen atoms in vacuum. Using the time-of-flight of the muonic atoms, the energy-dependent information of muonic reactions are obtained in direct manner.We discuss some unique measurements enabled by the new technique, with emphasis on processes relevant to muon catalyzed fusion.

  15. Atomic hydrogen storage. [cryotrapping and magnetic field strength

    Science.gov (United States)

    Woollam, J. A. (Inventor)

    1980-01-01

    Atomic hydrogen, for use as a fuel or as an explosive, is stored in the presence of a strong magnetic field in exfoliated layered compounds such as molybdenum disulfide or an elemental layer material such as graphite. The compound is maintained at liquid temperatures and the atomic hydrogen is collected on the surfaces of the layered compound which are exposed during delamination (exfoliation). The strong magnetic field and the low temperature combine to prevent the atoms of hydrogen from recombining to form molecules.

  16. Radiolytic and thermolytic bubble gas hydrogen composition

    Energy Technology Data Exchange (ETDEWEB)

    Woodham, W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-12-11

    This report describes the development of a mathematical model for the estimation of the hydrogen composition of gas bubbles trapped in radioactive waste. The model described herein uses a material balance approach to accurately incorporate the rates of hydrogen generation by a number of physical phenomena and scale the aforementioned rates in a manner that allows calculation of the final hydrogen composition.

  17. Characterization of polycyclic aromatic hydrocarbon emissions in the particulate and gas phase from smoldering mosquito coils containing various atomic hydrogen/carbon ratios

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Tzu-Ting, E-mail: d89844001@ntu.edu.tw [Department of Environmental Engineering and Health, Yuanpei University, No. 306, Yuanpei St., Hsin Chu 30015, Taiwan (China); Lin, Shaw-Tao [Department of Applied Chemistry, Providence University, No. 200 Chung-Chi Rd., Salu Dist., Taichung City 43301, Taiwan (China); Lin, Tser-Sheng [Department of Safety, Health, and Environmental Engineering, National United University, 2 Lien Da, Maioli 360, Taiwan (China); Chung, Hua-Yi [Department of Environmental Engineering and Health, Yuanpei University, No. 306, Yuanpei St., Hsin Chu 30015, Taiwan (China)

    2015-02-15

    The polycyclic aromatic hydrocarbon emissions in particulate and gas phases generated from smoldering mosquito coils containing various atomic H/C ratios were examined. Five types of mosquito coils were burned in a test chamber with a total airflow rate of 8.0 L/min at a constant relative humidity and temperature. The concentrations of individual PAHs were determined using the GC/MS technique. Among the used mosquito coils, the atomic H/C ratio ranged from 1.23 to 1.57, yielding total mass, gaseous, and particulate PAH emission factors of 28.17–78.72 mg/g, 26,139.80–35,932.98 and 5735.22–13,431.51 ng/g, respectively. The various partitions of PAHs in the gaseous and particulate phases were in the ranges, 70.26–83.70% and 16.30–29.74% for the utilized mosquito coils. The carcinogenic potency of PAH emissions in the particulate phase (203.82–797.76 ng/g) was approximately 6.92–25.08 times higher than that of the gaseous phase (26.27–36.07 ng/g). Based on the analyses of PAH emissions, mosquito coils containing the lowest H/C ratio, a low oxygen level, and additional additives (i.e., CaCO{sub 3}) are recommended for minimizing the production of total PAH emission factors and carcinogenic potency. - Highlights: • PAHs emissions are influenced by mosquito coils containing various atomic H/C ratios. • The PAHs generated by burning mosquito coils mainly occur in the gaseous phase. • Total TEQ emission factors of PAHs mainly consisted of the particulate phase (> 87%). • The BaP and BaA accounted for 71.13–77.28% of the total TEQ emission factors. • Special PAH ratios were regarded as characteristic ratios for burning mosquito coil.

  18. 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....

  19. Unparticle physics constraints from the hydrogen atom

    Energy Technology Data Exchange (ETDEWEB)

    Wondrak, Michael Florian; Nicolini, Piero; Bleicher, Marcus [Frankfurt Institute for Advanced Studies (FIAS), Frankfurt am Main (Germany); Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet Frankfurt am Main, Frankfurt am Main (Germany)

    2016-07-01

    Unparticle stuff has been proposed as an extension of the Standard Model of particle physics by including scale invariant fields. In the framework of effective field theory, it describes the low-energy limit of a so-called Banks-Zaks sector which exhibits scale invariance below an energy scale Λ{sub U}. Unparticle fields are characterized by a non-integer canonical scaling dimension d{sub U}, which leads to unusual properties like resembling a fractional number of (un)particles. The existence of unparticle stuff may be detected experimentally through the interaction with conventional matter. After a review on the unparticle theory and the static potential due to virtual unparticle exchange, we focus on its impact on hydrogen atom energy levels. We obtain the energy shift of the ground state by using Rayleigh-Schroedinger perturbation theory and compare it with experimental data. In this way, bounds on the energy scale Λ{sub U} as a function of d{sub U} are derived. Finally, we offer a comparison with existing constraints in literature like the lepton magnetic anomaly. For some parameter regimes, the hydrogen bound provides competitive results.

  20. Emission of fast non-Maxwellian hydrogen atoms in low-density laboratory plasma

    Science.gov (United States)

    Brandt, Christian; Marchuk, Oleksandr; Pospieszczyk, Albrecht; Dickheuer, Sven

    2017-03-01

    The source of strong and broad emission of the Balmer-α line in mixed plasmas of hydrogen (or deuterium) and noble gases in front of metallic surfaces is a subject of controversial discussion of many plasma types. In this work the excitation source of the Balmer lines is investigated by means of optical emission spectroscopy in the plasma device PSI-2. Neutral fast non-Maxwellian hydrogen atoms are produced by acceleration of hydrogen ions towards an electrode immersed into the plasma. By variation of the electrode potential the energy of ions and in turn of reflected fast atoms can be varied in the range of 40-300 eV. The fast atoms in front of the electrode are observed simultaneously by an Echelle spectrometer (0.001 nm/channel) and by an imaging spectrometer (0.01 nm/channel) up to few cm in the plasma. Intense excitation channels of the Balmer lines are observed when hydrogen is mixed with argon or with krypton. Especially in Ar-H and Ar-D mixed plasmas the emission of fast hydrogen atoms is very strong. Intermixing hydrogen with other noble gases (He, Ne or Xe) one observes the same effect however the emission is one order of magnitude less compared to Kr-H or Kr-D plasmas. It is shown, that the key process, impacting this emission, is the binary collision between the fast neutral hydrogen atom and the noble gas atom. Two possible sources of excitation are discussed in details: one is the excitation of hydrogen atoms by argon atoms in the ground state and the second one is the process of the so-called excitation transfer between the metastable states of noble gases and hydrogen. In the latter case the atomic data for excitation of Balmer lines are still not available in literature. Further experimental investigations are required to conclude on the source process of fast atom emission.

  1. Removing hydrogen sulphide from a gas mixture

    Energy Technology Data Exchange (ETDEWEB)

    Baar, J.F. Van; Lith, W.J. Van.

    1990-05-08

    A process is provided for selectively removing hydrogen sulfide from a gas mixture containing hydrogen sulfide and carbon dioxide, such as natural gas or a reduced off-gas from the Claus process. The process comprises contacting the gas mixture with a liquid absorbent composition including an aminopyridine, such as 4-dimethylaminopyridine. The absorbent composition suitably contains between 1 and 2 moles of aminopyridine per liter of physical solvent (such as sulfolane). Contacting is carried out at 20-80{degree}C and at approximately atmospheric pressure, usually in countercurrent fashion in a gas/liquid contacting column. The rich absorbent composition laden with hydrogen sulfide is regenerated by heating the solution and/or stripping the composition with an inert gas such as steam. Experiments are described to illustrate the process of the invention. 2 tabs.

  2. Gas-driven hydrogen permeation through tungsten-coated graphite

    Energy Technology Data Exchange (ETDEWEB)

    Golubeva, A.V., E-mail: anna-golubeva@yandex.ru [RRC ' Kurchatov Institute' , Ac. Kurchatov sq., 1/1, Moscow RU-123182 (Russian Federation); Spitsyn, A.V., E-mail: spitsyn@nfi.kiae.ru [RRC ' Kurchatov Institute' , Ac. Kurchatov sq., 1/1, Moscow RU-123182 (Russian Federation); Mayer, M. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstrasse 2, D-85748 Garching (Germany); Cherkez, D.I. [RRC ' Kurchatov Institute' , Ac. Kurchatov sq., 1/1, Moscow RU-123182 (Russian Federation); Schwarz-Selinger, T.; Koch, F.; Lindig, S. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmannstrasse 2, D-85748 Garching (Germany); Skovoroda, A.A. [RRC ' Kurchatov Institute' , Ac. Kurchatov sq., 1/1, Moscow RU-123182 (Russian Federation)

    2011-08-01

    Hydrogen gas-driven permeation through graphite coated with different types of tungsten coatings with thicknesses up to 200 {mu}m has been investigated. The substrate material was fine-grain graphite R5710 and R6710, which properties with respect to hydrogen transport are well known . Magnetron-sputtered W coatings of thicknesses 1 and 3 {mu}m and two coatings of ASDEX Upgrade were investigated: A 3 {mu}m thick layer of tungsten deposited by physical vapor deposition (PVD-W) and 200 {mu}m thick layers of tungsten deposited by plasma-spaying in vacuum (VPS-W). The gas-driven permeation was investigated at a pressure gradient of 10{sup -2}-150 Pa. The gas-driven permeation occurs through the carbon base-materials by hydrogen molecular gas flow through the internal porosity network rather than hydrogen atom diffusion through the graphite lattice. It was found that W coatings with thicknesses up to 3 {mu}m are transparent for hydrogen gas penetration and do not influence the permeability of coated fine-grain graphite, because the open porosity system of graphite remains open. Even a 200 {mu}m thick layer of VPS-W has an open system of connected pores, which connects the front and rear surfaces of the deposited layer.

  3. Hirshfeld atom refinement for modelling strong hydrogen bonds.

    Science.gov (United States)

    Woińska, Magdalena; Jayatilaka, Dylan; Spackman, Mark A; Edwards, Alison J; Dominiak, Paulina M; Woźniak, Krzysztof; Nishibori, Eiji; Sugimoto, Kunihisa; Grabowsky, Simon

    2014-09-01

    High-resolution low-temperature synchrotron X-ray diffraction data of the salt L-phenylalaninium hydrogen maleate are used to test the new automated iterative Hirshfeld atom refinement (HAR) procedure for the modelling of strong hydrogen bonds. The HAR models used present the first examples of Z' > 1 treatments in the framework of wavefunction-based refinement methods. L-Phenylalaninium hydrogen maleate exhibits several hydrogen bonds in its crystal structure, of which the shortest and the most challenging to model is the O-H...O intramolecular hydrogen bond present in the hydrogen maleate anion (O...O distance is about 2.41 Å). In particular, the reconstruction of the electron density in the hydrogen maleate moiety and the determination of hydrogen-atom properties [positions, bond distances and anisotropic displacement parameters (ADPs)] are the focus of the study. For comparison to the HAR results, different spherical (independent atom model, IAM) and aspherical (free multipole model, MM; transferable aspherical atom model, TAAM) X-ray refinement techniques as well as results from a low-temperature neutron-diffraction experiment are employed. Hydrogen-atom ADPs are furthermore compared to those derived from a TLS/rigid-body (SHADE) treatment of the X-ray structures. The reference neutron-diffraction experiment reveals a truly symmetric hydrogen bond in the hydrogen maleate anion. Only with HAR is it possible to freely refine hydrogen-atom positions and ADPs from the X-ray data, which leads to the best electron-density model and the closest agreement with the structural parameters derived from the neutron-diffraction experiment, e.g. the symmetric hydrogen position can be reproduced. The multipole-based refinement techniques (MM and TAAM) yield slightly asymmetric positions, whereas the IAM yields a significantly asymmetric position.

  4. Integrated Mirco-Machined Hydrogen Gas Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Frank DiMeoJr. Ing--shin Chen

    2005-12-15

    The widespread use of hydrogen as both an industrial process gas and an energy storage medium requires fast, selective detection of hydrogen gas. This report discusses the development of a new type of solid-state hydrogen gas sensor that couples novel metal hydride thin films with a MEMS (Micro-Electro-Mechanical System) structure known as a micro-hotplate. In this project, Micro-hotplate structures were overcoated with engineered multilayers that serve as the active hydrogen-sensing layer. The change in electrical resistance of these layers when exposed to hydrogen gas was the measured sensor output. This project focused on achieving the following objectives: (1) Demonstrating the capabilities of micro-machined H2 sensors; (2) Developing an understanding of their performance; (3) Critically evaluating the utility and viability of this technology for life safety and process monitoring applications. In order to efficiently achieve these objectives, the following four tasks were identified: (1) Sensor Design and Fabrication; (2) Short Term Response Testing; (3) Long Term Behavior Investigation; (4) Systems Development. Key findings in the project include: The demonstration of sub-second response times to hydrogen; measured sensitivity to hydrogen concentrations below 200 ppm; a dramatic improvement in the sensor fabrication process and increased understanding of the processing properties and performance relationships of the devices; the development of improved sensing multilayers; and the discovery of a novel strain based hydrogen detection mechanism. The results of this program suggest that this hydrogen sensor technology has exceptional potential to meet the stringent demands of life safety applications as hydrogen utilization and infrastructure becomes more prevalent.

  5. Hydrogen-rich gas generator

    Science.gov (United States)

    Houseman, J.; Cerini, D. J. (Inventor)

    1976-01-01

    A process and apparatus are described for producing hydrogen-rich product gases. A spray of liquid hydrocarbon is mixed with a stream of air in a startup procedure and the mixture is ignited for partial oxidation. The stream of air is then heated by the resulting combustion to reach a temperature such that a signal is produced. The signal triggers a two way valve which directs liquid hydrocarbon from a spraying mechanism to a vaporizing mechanism with which a vaporized hydrocarbon is formed. The vaporized hydrocarbon is subsequently mixed with the heated air in the combustion chamber where partial oxidation takes place and hydrogen-rich product gases are produced.

  6. Pregalactic black hole formation with an atomic hydrogen equation of state

    NARCIS (Netherlands)

    Spaans, Marco; Silk, Joseph

    2006-01-01

    The polytropic equation of state of an atomic hydrogen gas is examined for primordial halos with baryonic masses of M-h similar to 10(7)-10(9) M-circle dot. For roughly isothermal collapse around 10(4) K, we find that line trapping of Ly alpha (H I and He II) photons causes the polytropic exponent

  7. Determination of the Relative Atomic Masses of Metals by Liberation of Molecular Hydrogen

    Science.gov (United States)

    Waghorne, W. Earle; Rous, Andrew J.

    2009-01-01

    Students determine the relative atomic masses of calcium, magnesium, and aluminum by reaction with hydrochloric acid and measurement of the volume of hydrogen gas liberated. The experiment demonstrates stoichiometry and illustrates clearly that mass of the reagent is not the determinant of the amounts in chemical reactions. The experiment is…

  8. Embedded-atom method potential for modeling hydrogen and hydrogen-defect interaction in tungsten

    Science.gov (United States)

    Wang, Li-Fang; Shu, Xiaolin; Lu, Guang-Hong; Gao, Fei

    2017-11-01

    An embedded-atom method potential has been developed for modeling hydrogen in body-centered-cubic (bcc) tungsten by fitting to an extensive database of density functional theory (DFT) calculations. Comprehensive evaluations of the new potential are conducted by comparing various hydrogen properties with DFT calculations and available experimental data, as well as all the other tungsten–hydrogen potentials. The new potential accurately reproduces the point defect properties of hydrogen, the interaction among hydrogen atoms, the interplay between hydrogen and a monovacancy, and the thermal diffusion of hydrogen in tungsten. The successful validation of the new potential confirms its good reliability and transferability, which enables large-scale atomistic simulations of tungsten–hydrogen system. The new potential is afterward employed to investigate the interplay between hydrogen and other defects, including [1 1 1] self-interstitial atoms (SIAs) and vacancy clusters in tungsten. It is found that both the [1 1 1] SIAs and the vacancy clusters exhibit considerable attraction for hydrogen. Hydrogen solution and diffusion in strained tungsten are also studied using the present potential, which demonstrates that tensile (compressive) stress facilitates (impedes) hydrogen solution, and isotropic tensile (compressive) stress impedes (facilitates) hydrogen diffusion while anisotropic tensile (compressive) stress facilitates (impedes) hydrogen diffusion.

  9. The EAGLE simulations: atomic hydrogen associated with galaxies

    Science.gov (United States)

    Crain, Robert A.; Bahé, Yannick M.; Lagos, Claudia del P.; Rahmati, Alireza; Schaye, Joop; McCarthy, Ian G.; Marasco, Antonino; Bower, Richard G.; Schaller, Matthieu; Theuns, Tom; van der Hulst, Thijs

    2017-02-01

    We examine the properties of atomic hydrogen (H I) associated with galaxies in the Evolution and Assembly of GaLaxies and their Environments (EAGLE) simulations of galaxy formation. EAGLE's feedback parameters were calibrated to reproduce the stellar mass function and galaxy sizes at z = 0.1, and we assess whether this calibration also yields realistic H I properties. We estimate the self-shielding density with a fitting function calibrated using radiation transport simulations, and correct for molecular hydrogen with empirical or theoretical relations. The `standard-resolution' simulations systematically underestimate H I column densities, leading to an H I deficiency in low-mass (M⋆ EAGLE simulations featuring a factor of 8 (2) better mass (spatial) resolution, within which the H I mass of galaxies evolves more mildly from z = 1 to 0 than in the standard-resolution simulations. The largest volume simulation reproduces the observed clustering of H I systems, and its dependence on H I richness. At fixed M⋆, galaxies acquire more H I in simulations with stronger feedback, as they become associated with more massive haloes and higher infall rates. They acquire less H I in simulations with a greater star formation efficiency, since the star formation and feedback necessary to balance the infall rate is produced by smaller gas reservoirs. The simulations indicate that the H I of present-day galaxies was acquired primarily by the smooth accretion of ionized, intergalactic gas at z ≃ 1, which later self-shields, and that only a small fraction is contributed by the reincorporation of gas previously heated strongly by feedback. H I reservoirs are highly dynamic: over 40 per cent of H I associated with z = 0.1 galaxies is converted to stars or ejected by z = 0.

  10. Topics in atomic hydrogen standard research and applications

    Science.gov (United States)

    Peters, H. E.

    1971-01-01

    Hydrogen maser based frequency and time standards have been in continuous use at NASA tracking stations since February 1970, while laboratory work at Goddard has continued in the further development and improvement of hydrogen masers. Concurrently, experimental work has been in progress with a new frequency standard based upon the hydrogen atom using the molecular beam magnetic resonance method. Much of the hydrogen maser technology is directly applicable to the new hydrogen beam standard, and calculations based upon realistic data indicate that the accuracy potential of the hydrogen atomic beam exceeds that of either the cesium beam tube or the hydrogen maser, possibly by several orders of magnitude. In addition, with successful development, the hydrogen beam standard will have several other performance advantages over other devices, particularly exceptional stability and long continuous operating life. Experimental work with a new laboratory hydrogen beam device has recently resulted in the first resonance transition curves, measurements of relative state populations, beam intensities, etc. The most important aspects of both the hydrogen maser and the hydrogen beam work are covered.

  11. Excited states of muonium in atomic hydrogen

    Indian Academy of Sciences (India)

    Muonium formation in excited states in muon-hydrogen charge-exchange collision is investigated using a method developed in a previous paper. Differential cross-section results are found to resemble positronium formation cross-section results of positron-hydrogen charge-exchange problem. Forward differential and ...

  12. Atomic displacements due to interstitial hydrogen in Cu and Pd

    Indian Academy of Sciences (India)

    The density functional theory (DFT) is used to study the atomic interactions in transition metal-based interstitial alloys. The strain field is calculated in the discrete lattice model using Kanzaki method. The total energy and hence atomic forces between interstitial hydrogen and transition metal hosts are calculated using DFT.

  13. Atomic displacements due to interstitial hydrogen in Cu and Pd

    Indian Academy of Sciences (India)

    Abstract. The density functional theory (DFT) is used to study the atomic interac- tions in transition metal-based interstitial alloys. The strain field is calculated in the discrete lattice model using Kanzaki method. The total energy and hence atomic forces between interstitial hydrogen and transition metal hosts are calculated ...

  14. Dynamic nuclear polarization of high-density atomic hydrogen in solid mixtures of molecular hydrogen isotopes.

    Science.gov (United States)

    Sheludiakov, S; Ahokas, J; Järvinen, J; Zvezdov, D; Vainio, O; Lehtonen, L; Vasiliev, S; Mao, S; Khmelenko, V V; Lee, D M

    2014-12-31

    We report on magnetic resonance studies of high-density atomic hydrogen and deuterium in solid hydrogen matrices at temperatures below 1 K. Average concentrations of H atoms ≈3×10(19)  cm(-3) are obtained in chemical tunneling reactions of isotope exchange with D atoms. The products of these reactions are closely located pairs of H atoms near D2 molecules with strong exchange interactions. We discovered a dynamic nuclear polarization effect on H atoms created by pumping the center of the H electron spin resonance spectrum, similar to the Overhauser effect in metals. Our results indicate that H atoms may be arranged inside molecular matrices at separations equivalent to local concentrations of 2.6×10(21)  cm(-3). This opens up a way to build a metallic state of atomic hydrogen at zero pressure.

  15. Detection of gas atoms with carbon nanotubes

    Science.gov (United States)

    Arash, B.; Wang, Q.

    2013-01-01

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

  16. Characterization of an atomic hydrogen source for charge exchange experiments

    Energy Technology Data Exchange (ETDEWEB)

    Leutenegger, M. A. [NASA Goddard Space Flight Center, Code 662, Greenbelt, Maryland 20771 (United States); CRESST/University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250 (United States); Beiersdorfer, P.; Brown, G. V.; Magee, E. W. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Betancourt-Martinez, G. L. [NASA Goddard Space Flight Center, Code 662, Greenbelt, Maryland 20771 (United States); University of Maryland College Park, College Park, Maryland 20742 (United States); Hell, N. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Dr. Karl-Remeis-Sternwarte and ECAP, FAU Erlangen-Nürnberg, Sternwartstr. 7, 96049 Bamberg (Germany); Kelley, R. L.; Kilbourne, C. A.; Porter, F. S. [NASA Goddard Space Flight Center, Code 662, Greenbelt, Maryland 20771 (United States)

    2016-11-15

    We characterized the dissociation fraction of a thermal dissociation atomic hydrogen source by injecting the mixed atomic and molecular output of the source into an electron beam ion trap containing highly charged ions and recording the x-ray spectrum generated by charge exchange using a high-resolution x-ray calorimeter spectrometer. We exploit the fact that the charge exchange state-selective capture cross sections are very different for atomic and molecular hydrogen incident on the same ions, enabling a clear spectroscopic diagnostic of the neutral species.

  17. Interactions of atomic hydrogen with amorphous SiO2

    Science.gov (United States)

    Yue, Yunliang; Wang, Jianwei; Zhang, Yuqi; Song, Yu; Zuo, Xu

    2018-03-01

    Dozens of models are investigated by the first-principles calculations to simulate the interactions of an atomic hydrogen with a defect-free random network of amorphous SiO2 (a-SiO2) and oxygen vacancies. A wide variety of stable configurations are discovered due to the disorder of a-SiO2, and their structures, charges, magnetic moments, spin densities, and density of states are calculated. The atomic hydrogen interacts with the defect-free a-SiO2 in positively or negatively charged state, and produces the structures absent in crystalline SiO2. It passivates the neutral oxygen vacancies and generates two neutral hydrogenated E‧ centers with different Si dangling bond projections. Electron spin resonance parameters, including Fermi contacts, and g-tensors, are calculated for these centers. The atomic hydrogen interacts with the positive oxygen vacancies in dimer configuration, and generate four different positive hydrogenated defects, two of which are puckered like the Eγ‧ centers. This research helps to understand the interactions between an atomic hydrogen, and defect-free a-SiO2 and oxygen vacancies, which may generate the hydrogen-complexed defects that play a key role in the degeneration of silicon/silica-based microelectronic devices.

  18. Performance of a hydrogen/deuterium polarized gas target in a storage ring

    NARCIS (Netherlands)

    van Buuren, L.D.; Szczerba, D.; van den Brand, J.F.J.; Bulten, H.J.; Klous, S.; Mul, F.A.; Poolman, H.R.; Simani, M.C.

    2001-01-01

    The performance of a hydrogen/deuterium polarized gas target in a storage ring is presented. The target setup consisted of an atomic beam source, a cryogenic storage cell and a Breit-Rabi polarimeter. High frequency transition units were constructed to produce vector polarized hydrogen and

  19. A momentum filter for atomic gas

    Science.gov (United States)

    Xiong, Wei; Zhou, Xiaoji; Yue, Xuguang; Zhai, Yueyang; Chen, Xuzong

    2013-06-01

    We propose and demonstrate a momentum filter for atomic gas-based on a designed Talbot-Lau interferometer. It consists of two identical optical standing-wave pulses separated by a delay equal to odd multiples of the half Talbot time. The one-dimensional momentum width along the long direction of a cigar-shaped condensate is rapidly and greatly purified to a minimum, which corresponds to the ground state energy of the confining trap in our experiment. We find good agreement between theoretical analysis and experimental results. The filter is also effective for non-condensed cold atoms and could be applied widely.

  20. Diffusion mobility of the hydrogen atom with allowance for the anharmonic attenuation of migrating atom state

    Energy Technology Data Exchange (ETDEWEB)

    Kashlev, Y.A., E-mail: yakashlev@yandex.ru

    2017-04-15

    Evolution of vibration relaxation of hydrogen atoms in metals with the close-packed lattice at high and medium temperatures is investigated based on non-equilibrium statistical thermodynamics, in that number on using the retarded two-time Green function method. In accordance with main kinetic equation – the generalized Fokker- Plank- Kolmogorov equation, anharmonism of hydrogen atoms vibration in potential wells does not make any contribution to collision effects. It influences the relaxation processes at the expense of interference of fourth order anharmonism with single-phonon scattering on impurity hydrogen atoms. Therefore, the total relaxation time of vibration energy of system metal-hydrogen is written as a product of two factors: relaxation time of system in harmonic approximation and dimensionless anharmonic attenuation of quantum hydrogen state.

  1. Atomic White-Out: Enabling Atomic Circuitry through Mechanically Induced Bonding of Single Hydrogen Atoms to a Silicon Surface.

    Science.gov (United States)

    Huff, Taleana R; Labidi, Hatem; Rashidi, Mohammad; Koleini, Mohammad; Achal, Roshan; Salomons, Mark H; Wolkow, Robert A

    2017-09-26

    We report the mechanically induced formation of a silicon-hydrogen covalent bond and its application in engineering nanoelectronic devices. We show that using the tip of a noncontact atomic force microscope (NC-AFM), a single hydrogen atom could be vertically manipulated. When applying a localized electronic excitation, a single hydrogen atom is desorbed from the hydrogen-passivated surface and can be transferred to the tip apex, as evidenced from a unique signature in frequency shift curves. In the absence of tunnel electrons and electric field in the scanning probe microscope junction at 0 V, the hydrogen atom at the tip apex is brought very close to a silicon dangling bond, inducing the mechanical formation of a silicon-hydrogen covalent bond and the passivation of the dangling bond. The functionalized tip was used to characterize silicon dangling bonds on the hydrogen-silicon surface, which was shown to enhance the scanning tunneling microscope contrast, and allowed NC-AFM imaging with atomic and chemical bond contrasts. Through examples, we show the importance of this atomic-scale mechanical manipulation technique in the engineering of the emerging technology of on-surface dangling bond based nanoelectronic devices.

  2. The HERMES polarized hydrogen and deuterium gas target in the HERA electron storage ring

    NARCIS (Netherlands)

    Airapetian, A.; Blok, H.P.; Chen, T.; Hesselink, W.H.A.; Laziev, A.; Volmer, J.; Wang, S.; Smit, G.P.

    2005-01-01

    The HERMES hydrogen and deuterium nuclear-polarized gas targets have been in use since 1996 with the polarized electron beam of HERA at DESY to study the spin structure of the nucleon. Polarized atoms from a Stern-Gerlach Atomic Beam Source are injected into a storage cell internal to the HERA

  3. The Atomic Bose Gas in Flatland

    Science.gov (United States)

    Hadzibabic, Z.; Krüger, P.; Cheneau, M.; Battelier, B.; Dalibard, J.

    2006-11-01

    We describe a recent experiment performed with rubidium atoms (87Rb), aiming at studying the coherence properties of a two-dimensional gas of bosonic particles at low temperature. We have observed in particular a Berezinskii-Kosterlitz-Thouless (BKT) type crossover in the system, using a matter wave heterodyning technique. At low temperatures, the gas is quasi-coherent on the length scale set by the system size. As the temperature is increased, the loss of long-range coherence coincides with the onset of the proliferation of free vortices, in agreement with the microscopic BKT theory.

  4. 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.

  5. A momentum filter for atomic gas

    OpenAIRE

    Xiong, Wei; Zhou, Xiaoji; Yue, Xuguang; Zhai, Yueyang; Chen, Xuzong

    2013-01-01

    We propose and demonstrate a momentum filter for atomic gas based on a designed Talbot-Lau interferometer. It consists in two identical optical standing wave pulses separated by a delay equal to odd multiples of the half Talbot time. The one dimensional momentum width along the long direction of a cigar shape condensate is rapidly and greatly purified to a minimum, which corresponds to the ground state energy of the confining trap in our experiment. We find good agreement between theoretical ...

  6. Excited states of muonium in atomic hydrogen

    Indian Academy of Sciences (India)

    Differential cross-section results are found to resemble positronium formation cross-section results of positron–hydrogen charge-exchange problem. Forward ... using velocity scaling are compared with the results of the present calculation. .... to carry out calculations for e− capture by muon into n = 2 and n = 3 states.

  7. Compressorless Gas Storage and Regenerative Hydrogen Purification Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Microwave regenerative sorption media gas storage/delivery techniques are proposed to address both compressed gas management and hydrogen purification requirements...

  8. Refuelling stations for hydrogen or reformate gas

    Energy Technology Data Exchange (ETDEWEB)

    Silversand, Fredrik [CATATOR AB, Lund (Sweden)

    2006-02-15

    A prestudy concerning refuelling stations for reformate gas/hydrogen has been performed on the request of Swedish Gas Centre. The plan is to build a small-scale fuel processor for said application during 2006 as a continuation of the RandD programme in the fuel processing area. Catator has designed and evaluated small-scale fuel processors in a series of SGC-projects. The fuel processor system was abbreviated 'Stur-unit' and contained reactors for steam reforming, water-gas shift and preferential oxidation, tied together in a single train unit. The STUR-unit is operated at atmospheric conditions and will produce reformate gas of fuel cell quality (normally less than 20 ppm of CO). Catator has designed and delivered a number of Stur-units ranging from 1 nm{sup 3} to 50 nm{sup 3}/hr of hydrogen. Different fuels have been evaluated, both gases and liquids. Catator has also designed a pressurised system together with Intelligent Energy (abbreviated 'Hestia-unit'). This unit operates at 5-10 bar(a) and utilizes physical purification by means of fast-cycle PSA to provide essential pure hydrogen. Both units have been subjected to successful long-term testing. The hydrogen demand in Malmoe (the proposed location for the refuelling station) is presently low and irregular since only two buses utilize Hythane (a mixture between natural gas and hydrogen) at the moment. The interest for hydrogen and hydrogen containing fuels is, however, expected to increase in a near future. E.ON Gas (the owner of the existing refuelling station) has forwarded a number of specifications for the fuel processor system. The unit shall operate on natural gas and biogas. Bio-derived liquid fuels (bio ethanol and E85 - a mixture between ethanol and gasoline) could also be interesting alternatives. Depending on the low demand for hydrogen (average of about 1 nm{sup 3}/hr), the production capacity can be rather low - 5-10 nm{sup 3}/hr is probably more than enough for the time being

  9. Gas diffusion electrodes improve hydrogen gas mass transfer for a hydrogen oxidizing bioanode.

    Science.gov (United States)

    Rodenas, Pau; Zhu, Fangqi; Ter Heijne, Annemiek; Sleutels, Tom; Saakes, Michel; Buisman, Cees

    2017-12-01

    Bioelectrochemical systems (BESs) are capable of recovery of metals at a cathode through oxidation of organic substrate at an anode. Recently, also hydrogen gas was used as an electron donor for recovery of copper in BESs. Oxidation of hydrogen gas produced a current density of 0.8 A m-2 and combined with Cu2+ reduction at the cathode, produced 0.25 W m-2. The main factor limiting current production was the mass transfer of hydrogen to the biofilm due to the low solubility of hydrogen in the anolyte. Here, the mass transfer of hydrogen gas to the bioanode was improved by use of a gas diffusion electrode (GDE). With the GDE, hydrogen was oxidized to produce a current density of 2.9 A m-2 at an anode potential of -0.2 V. Addition of bicarbonate to the influent led to production of acetate, in addition to current. At a bicarbonate concentration of 50 mmol L-1, current density increased to 10.7 A m-2 at an anode potential of -0.2 V. This increase in current density could be due to oxidation of formed acetate in addition to oxidation of hydrogen, or enhanced growth of hydrogen oxidizing bacteria due to the availability of acetate as carbon source. The effect of mass transfer was further assessed through enhanced mixing and in combination with the addition of bicarbonate (50 mmol L-1) current density increased further to 17.1 A m-2. Hydrogen gas may offer opportunities as electron donor for bioanodes, with acetate as potential intermediate, at locations where excess hydrogen and no organics are available. © 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

  10. Atomic hydrogen distribution. [in Titan atmospheric model

    Science.gov (United States)

    Tabarie, N.

    1974-01-01

    Several possible H2 vertical distributions in Titan's atmosphere are considered with the constraint of 5 km-A a total quantity. Approximative calculations show that hydrogen distribution is quite sensitive to two other parameters of Titan's atmosphere: the temperature and the presence of other constituents. The escape fluxes of H and H2 are also estimated as well as the consequent distributions trapped in the Saturnian system.

  11. Relativistic Hydrogen-Like Atom on a Noncommutative Phase Space

    Science.gov (United States)

    Masum, Huseyin; Dulat, Sayipjamal; Tohti, Mutallip

    2017-09-01

    The energy levels of hydrogen-like atom on a noncommutative phase space were studied in the framework of relativistic quantum mechanics. The leading order corrections to energy levels 2 S 1/2, 2 P 1/2 and 2 P 3/2 were obtained by using the 𝜃 and the \\bar θ modified Dirac Hamiltonian of hydrogen-like atom on a noncommutative phase space. The degeneracy of the energy levels 2 P 1/2 and 2 P 3/2 were removed completely by 𝜃-correction. And the \\bar θ -correction shifts these energy levels.

  12. Fast metastable hydrogen atoms from H2 molecules: twin atoms

    Directory of Open Access Journals (Sweden)

    Trimèche A.

    2015-01-01

    Full Text Available It is a difficult task to obtain “twin atoms”, i.e. pairs of massive particles such that one can perform experiments in the same fashion that is routinely done with “twin photons”. One possible route to obtain such pairs is by dissociating homonuclear diatomic molecules. We address this possibility by investigating the production of metastable H(2s atoms coming from the dissociation of cold H2 molecules produced in a Campargue nozzle beam crossing an electron beam from a high intensity pulsed electron gun. Dissociation by electron impact was chosen to avoid limitations of target molecular excited states due to selection rules. Detectors placed several centimeters away from the collision center, and aligned with respect to possible common molecular dissociation channel, analyze the neutral fragments as a function of their time-of-flight (TOF through Lyman-α detection. Evidence for the first time observed coincidence of pairs of H(2s atoms obtained this way is presented.

  13. Variational perturbation treatment of the confined hydrogen atom

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, H E Jr, E-mail: ed.montgomery@centre.edu [Chemistry Program, Centre College, 600 West Walnut Street, Danville, KY 40422-1394 (United States)

    2011-09-15

    The Schroedinger equation for the ground state of a hydrogen atom confined at the centre of an impenetrable cavity is treated using variational perturbation theory. Energies calculated from variational perturbation theory are comparable in accuracy to the results from a direct numerical solution. The goal of this exercise is to introduce the student to the effects of confinement on atomic systems using a tractable problem from which insight into variational perturbation theory may be gained.

  14. Study on Hydrogen Gas concentration to Voltage and Resistance using Semiconductor Hydrogen Gas Sensor

    Directory of Open Access Journals (Sweden)

    Ahmad Arif Hasibuan

    2016-10-01

    Full Text Available Study on hydrogen gas concentration to changes in voltage and resistance using semiconductor hydrogen gas sensor has been done. The system which has been designed will measure any changes in the voltage and resistance of the sensor automatically when the sensor is given a variation of concentration on hydrogen gas. On the condition of gas with low concentration, the sensor output voltage obtained worth 0:08 Volt and the sensor resistance value of 180 KΩ. On the increase in gas concentration causes an increase in sensor output voltage and a decrease in the value of resistance Studi tentang pengaruh konsentrasi kadar gas hidrogen terhadap perubahan tegangan dan resistansi menggunakan sensor gas hidrogen berbasis semikonduktor telah berhasil dilakukan. Sistem yang telah dirancang akan mengukur setiap perubahan tegangan dan resistansi secara digital pada sensor saat diberikan variasi terhadap konsentrasi kadar gas hidrogen. Pada kondisi gas dengan konsentrasi rendah diperoleh tegangan output sensor senilai 0.08 Volt dan nilai resistansi sensor sebesar 180 KΩ. Pada peningkatan konsentrasi gas menyebabkan peningkatan tegangan output sensor dan sebaliknya terjadi penurunan pada nilai resistansi

  15. Extensive Atrophic Gastritis Increases Intraduodenal Hydrogen Gas

    Directory of Open Access Journals (Sweden)

    Yoshihisa Urita

    2008-01-01

    Full Text Available Objective. Gastric acid plays an important part in the prevention of bacterial colonization of the gastrointestinal tract. If these bacteria have an ability of hydrogen (H2 fermentation, intraluminal H2 gas might be detected. We attempted to measure the intraluminal H2 concentrations to determine the bacterial overgrowth in the gastrointestinal tract. Patients and methods. Studies were performed in 647 consecutive patients undergoing upper endoscopy. At the time of endoscopic examination, we intubated the stomach and the descending part of the duodenum without inflation by air, and 20 mL of intraluminal gas samples of both sites was collected through the biopsy channel. Intraluminal H2 concentrations were measured by gas chromatography. Results. Intragastric and intraduodenal H2 gas was detected in 566 (87.5% and 524 (81.0% patients, respectively. The mean values of intragastric and intraduodenal H2 gas were 8.5±15.9 and 13.2±58.0 ppm, respectively. The intraduodenal H2 level was increased with the progression of atrophic gastritis, whereas the intragastric H2 level was the highest in patients without atrophic gastritis. Conclusions. The intraduodenal hydrogen levels were increased with the progression of atrophic gastritis. It is likely that the influence of hypochlorhydria on bacterial overgrowth in the proximal small intestine is more pronounced, compared to that in the stomach.

  16. Quantum-Classical Connection for Hydrogen Atom-Like Systems

    Science.gov (United States)

    Syam, Debapriyo; Roy, Arup

    2011-01-01

    The Bohr-Sommerfeld quantum theory specifies the rules of quantization for circular and elliptical orbits for a one-electron hydrogen atom-like system. This article illustrates how a formula connecting the principal quantum number "n" and the length of the major axis of an elliptical orbit may be arrived at starting from the quantum…

  17. Radial Matrix Elements of Hydrogen Atom and the Correspondence ...

    Indian Academy of Sciences (India)

    Radial dipole matrix elements having astrophysical importance have been computed for highly excited states of hydrogen atom. Computation is based on Heisenberg's form of correspondence principle for Coulomb potential. Particular attention has been paid to the choice of classical analogue (c) of principal quantum ...

  18. Variational Perturbation Treatment of the Confined Hydrogen Atom

    Science.gov (United States)

    Montgomery, H. E., Jr.

    2011-01-01

    The Schrodinger equation for the ground state of a hydrogen atom confined at the centre of an impenetrable cavity is treated using variational perturbation theory. Energies calculated from variational perturbation theory are comparable in accuracy to the results from a direct numerical solution. The goal of this exercise is to introduce the…

  19. Radial Matrix Elements of Hydrogen Atom and the Correspondence ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. Radial dipole matrix elements having astrophysical impor- tance have been computed for highly excited states of hydrogen atom. Computation is based on Heisenberg's form of correspondence principle for Coulomb potential. Particular attention has been paid to the choice of classical analogue (nc) of principal ...

  20. The Confined Hydrogen Atom with a Moving Nucleus

    Science.gov (United States)

    Fernandez, Francisco M.

    2010-01-01

    We study the hydrogen atom confined to a spherical box with impenetrable walls but, unlike earlier pedagogical articles on the subject, we assume that the nucleus also moves. We obtain the ground-state energy approximately by means of first-order perturbation theory and show that it is greater than that for the case in which the nucleus is clamped…

  1. Formation of ground and excited hydrogen atoms in proton ...

    Indian Academy of Sciences (India)

    2016-10-17

    Oct 17, 2016 ... Abstract. The inelastic scattering of proton with a potassium atom is treated for the first time as a three- channel problem within the framework of the improved coupled static approximation by assuming that the ground. (1s state) and the excited (2s state) hydrogen formation channels are open for seven ...

  2. Dirac equation, hydrogen atom spectrum and the Lamb shift in ...

    Indian Academy of Sciences (India)

    2017-04-12

    Apr 12, 2017 ... Abstract. We derive the relativistic Hamiltonian of hydrogen atom in dynamical non-commutative spaces. (DNCS or τ-space). Using this Hamiltonian we calculate the energy shift of the ground state as well the 2P1/2, 2S1/2 levels. In all the cases, the energy shift depends on the dynamical non-commutative ...

  3. Positron impact ionization of atomic hydrogen at low energies

    Indian Academy of Sciences (India)

    energies. K CHAKRABARTI. Department of Mathematics, Scottish Church College, 1 & 3 Urquhart Square, Calcutta 700 006,. India. MS received 26 June 2000. Abstract. Low energy positron impact ionization of atomic hydrogen is studies theoretically using the hyperspherical partial wave method of Das [1] in constant ΘЅѕ, ...

  4. Positron impact ionization of atomic hydrogen at low energies

    Indian Academy of Sciences (India)

    Low energy positron impact ionization of atomic hydrogen is studies theoretically using the hyperspherical partial wave method of Das [1] in constant 12, equal energy sharing geometry. The TDCS reveal considerable differences in physics compared to electron impact ionization under the same geometry.

  5. Schwinger variational calculation of ionization of hydrogen atoms for ...

    Indian Academy of Sciences (India)

    Schwinger variational calculation of ionization of hydrogen atoms for large momentum transfers. K CHAKRABARTI. Department of Mathematics, Scottish Church College, 1 & 3 Urquhart Square,. Kolkata 700 006, India. MS received 7 July 2001; revised 10 October 2001. Abstract. Schwinger variational principle is used here ...

  6. Suprathermal oxygen atoms in the Martian upper atmosphere: Contribution of the proton and hydrogen atom precipitation

    Science.gov (United States)

    Shematovich, V. I.

    2017-07-01

    This is a study of the kinetics and transport of hot oxygen atoms in the transition region (from the thermosphere to the exosphere) of the Martian upper atmosphere. It is assumed that the source of the hot oxygen atoms is the transfer of momentum and energy in elastic collisions between thermal atmospheric oxygen atoms and the high-energy protons and hydrogen atoms precipitating onto the Martian upper atmosphere from the solar-wind plasma. The distribution functions of suprathermal oxygen atoms by the kinetic energy are calculated. It is shown that the exosphere is populated by a large number of suprathermal oxygen atoms with kinetic energies up to the escape energy 2 eV; i.e., a hot oxygen corona is formed around Mars. The transfer of energy from the precipitating solar-wind plasma protons and hydrogen atoms to the thermal oxygen atoms leads to the formation of an additional nonthermal escape flux of atomic oxygen from the Martian atmosphere. The precipitation-induced escape flux of hot oxygen atoms may become dominant under the conditions of extreme solar events, such as solar flares and coronal mass ejections, as shown by recent observations onboard NASA's MAVEN spacecraft (Jakosky et al., 2015).

  7. Concerted hydrogen-atom abstraction in photosynthetic water oxidation.

    Science.gov (United States)

    Westphal, K L; Tommos, C; Cukier, R I; Babcock, G T

    2000-06-01

    Photosystem II evolves oxygen by using water in the unlikely role of a reductant. The absorption of sunlight by chlorophyll produces highly oxidizing equivalents that are filled with electrons stripped from water. This proton-coupled redox chemistry occurs at the oxygen-evolving complex, which contains a tetramanganese cluster, a redox-active tyrosine amino acid hydrogen-bonded to a histidine amino acid, a calcium ion and chloride. Hydrogen-atom abstraction by the tyrosyl radical from water bound to the manganese cluster is now widely held to occur in this process, at least for some of the steps in the catalytic cycle. We discuss kinetic and energetic constraints on the hydrogen-atom abstraction process.

  8. The Rydberg constant and proton size from atomic hydrogen

    Science.gov (United States)

    Beyer, Axel; Maisenbacher, Lothar; Matveev, Arthur; Pohl, Randolf; Khabarova, Ksenia; Grinin, Alexey; Lamour, Tobias; Yost, Dylan C.; Hänsch, Theodor W.; Kolachevsky, Nikolai; Udem, Thomas

    2017-10-01

    At the core of the “proton radius puzzle” is a four–standard deviation discrepancy between the proton root-mean-square charge radii (rp) determined from the regular hydrogen (H) and the muonic hydrogen (µp) atoms. Using a cryogenic beam of H atoms, we measured the 2S-4P transition frequency in H, yielding the values of the Rydberg constant R∞ = 10973731.568076(96) per meterand rp = 0.8335(95) femtometer. Our rp value is 3.3 combined standard deviations smaller than the previous H world data, but in good agreement with the µp value. We motivate an asymmetric fit function, which eliminates line shifts from quantum interference of neighboring atomic resonances.

  9. Reactivity and Catalytic Activity of Hydrogen Atom Chemisorbed Silver Clusters.

    Science.gov (United States)

    Manzoor, Dar; Pal, Sourav

    2015-06-18

    Metal clusters of silver have attracted recent interest of researchers as a result of their potential in different catalytic applications and low cost. However, due to the completely filled d orbital and very high first ionization potential of the silver atom, the silver-based catalysts interact very weakly with the reacting molecules. In the current work, density functional theory calculations were carried out to investigate the effect of hydrogen atom chemisorption on the reactivity and catalytic properties of inert silver clusters. Our results affirm that the hydrogen atom chemisorption leads to enhancement in the binding energy of the adsorbed O2 molecule on the inert silver clusters. The increase in the binding energy is also characterized by the decrease in the Ag-O and increase in the O-O bond lengths in the case of the AgnH silver clusters. Pertinent to the increase in the O-O bond length, a significant red shift in the O-O stretching frequency is also noted in the case of the AgnH silver clusters. Moreover, the hydrogen atom chemisorbed silver clusters show low reaction barriers and high heat of formation of the final products for the environmentally important CO oxidation reaction as compared to the parent catalytically inactive clusters. The obtained results were compared with those of the corresponding gold and hydrogen atom chemisorbed gold clusters obtained at the same level of theory. It is expected the current computational study will provide key insights for future advances in the design of efficient nanosilver-based catalysts through the adsorption of a small atom or a ligand.

  10. Classical-field model of the hydrogen atom

    Science.gov (United States)

    Rashkovskiy, Sergey A.

    2017-06-01

    It is shown that all of the basic properties of the hydrogen atom can be consistently described in terms of classical electrodynamics if instead of considering the electron to be a particle, we consider an electrically charged classical wave field—an "electron wave"—which is held by the electrostatic field of the proton. It is shown that quantum mechanics must be considered not as a theory of particles but as a classical field theory in the spirit of classical electrodynamics. In this case, we are not faced with difficulties in interpreting the results of the theory. In the framework of classical electrodynamics, all of the well-known regularities of the spontaneous emission of the hydrogen atom are obtained, which is usually derived in the framework of quantum electrodynamics. It is shown that there are no discrete states and discrete energy levels of the atom: the energy of the atom and its states change continuously. An explanation of the conventional corpuscular-statistical interpretation of atomic phenomena is given. It is shown that this explanation is only a misinterpretation of continuous deterministic processes. In the framework of classical electrodynamics, the nonlinear Schrödinger equation is obtained, which accounts for the inverse action of self-electromagnetic radiation of the electron wave and completely describes the spontaneous emissions of an atom.

  11. Electron-impact ionization of atomic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Baertschy, Mark D. [Univ. of California, Davis, CA (United States)

    2000-02-01

    Since the invention of quantum mechanics, even the simplest example of collisional breakup in a system of charged particles, e- + H → H+ + e- + e+, has stood as one of the last unsolved fundamental problems in atomic physics. A complete solution requires calculating the energies and directions for a final state in which three charged particles are moving apart. Advances in the formal description of three-body breakup have yet to lead to a viable computational method. Traditional approaches, based on two-body formalisms, have been unable to produce differential cross sections for the three-body final state. Now, by using a mathematical transformation of the Schrodinger equation that makes the final state tractable, a complete solution has finally been achieved, Under this transformation, the scattering wave function can be calculated without imposing explicit scattering boundary conditions. This approach has produced the first triple differential cross sections that agree on an absolute scale with experiment as well as the first ab initio calculations of the single differential cross section.

  12. Hydrogen gas storage in fluorinated ultramicroporous tunnel crystal.

    Science.gov (United States)

    Kataoka, Keisuke; Katagiri, Toshimasa

    2012-08-21

    We report hydrogen storage at an ordinary pressure due to a bottle-neck effect of an ultramicroporous crystal. Stored hydrogen was kept at an ordinary pressure below -110 °C. The amounts of stored hydrogen gas linearly correlated with the initial pressures. These phenomena suggested the ultramicroporous tunnels worked as a molecular gas cylinder.

  13. Advanced IGCC/Hydrogen Gas Turbine Development

    Energy Technology Data Exchange (ETDEWEB)

    York, William [General Electric Company, Schenectady, NY (United States); Hughes, Michael [General Electric Company, Schenectady, NY (United States); Berry, Jonathan [General Electric Company, Schenectady, NY (United States); Russell, Tamara [General Electric Company, Schenectady, NY (United States); Lau, Y. C. [General Electric Company, Schenectady, NY (United States); Liu, Shan [General Electric Company, Schenectady, NY (United States); Arnett, Michael [General Electric Company, Schenectady, NY (United States); Peck, Arthur [General Electric Company, Schenectady, NY (United States); Tralshawala, Nilesh [General Electric Company, Schenectady, NY (United States); Weber, Joseph [General Electric Company, Schenectady, NY (United States); Benjamin, Marc [General Electric Company, Schenectady, NY (United States); Iduate, Michelle [General Electric Company, Schenectady, NY (United States); Kittleson, Jacob [General Electric Company, Schenectady, NY (United States); Garcia-Crespo, Andres [General Electric Company, Schenectady, NY (United States); Delvaux, John [General Electric Company, Schenectady, NY (United States); Casanova, Fernando [General Electric Company, Schenectady, NY (United States); Lacy, Ben [General Electric Company, Schenectady, NY (United States); Brzek, Brian [General Electric Company, Schenectady, NY (United States); Wolfe, Chris [General Electric Company, Schenectady, NY (United States); Palafox, Pepe [General Electric Company, Schenectady, NY (United States); Ding, Ben [General Electric Company, Schenectady, NY (United States); Badding, Bruce [General Electric Company, Schenectady, NY (United States); McDuffie, Dwayne [General Electric Company, Schenectady, NY (United States); Zemsky, Christine [General Electric Company, Schenectady, NY (United States)

    2015-07-30

    The objective of this program was to develop the technologies required for a fuel flexible (coal derived hydrogen or syngas) gas turbine for IGCC that met DOE turbine performance goals. The overall DOE Advanced Power System goal was to conduct the research and development (R&D) necessary to produce coal-based IGCC power systems with high efficiency, near-zero emissions, and competitive capital cost. To meet this goal, the DOE Fossil Energy Turbine Program had as an interim objective of 2 to 3 percentage points improvement in combined cycle (CC) efficiency. The final goal is 3 to 5 percentage points improvement in CC efficiency above the state of the art for CC turbines in IGCC applications at the time the program started. The efficiency goals were for NOx emissions of less than 2 ppm NOx (@15 % O2). As a result of the technologies developed under this program, the DOE goals were exceeded with a projected 8 point efficiency improvement. In addition, a new combustion technology was conceived of and developed to overcome the challenges of burning hydrogen and achieving the DOE’s NOx goal. This report also covers the developments under the ARRA-funded portion of the program that include gas turbine technology advancements for improvement in the efficiency, emissions, and cost performance of gas turbines for industrial applications with carbon capture and sequestration. Example applications could be cement plants, chemical plants, refineries, steel and aluminum plants, manufacturing facilities, etc. The DOE’s goal for more than 5 percentage point improvement in efficiency was met with cycle analyses performed for representative IGCC Steel Mill and IGCC Refinery applications. Technologies were developed in this program under the following areas: combustion, larger latter stage buckets, CMC and EBC, advanced materials and coatings, advanced configurations to reduce cooling, sealing and rotor purge flows, turbine aerodynamics, advanced sensors, advancements in first

  14. Enhancing the hydrogen bond between the bridged hydrogen atom of diborane and ammonia.

    Science.gov (United States)

    Gao, Lei; Zhang, Xueying; Meng, Lingpeng; Zeng, Yanli

    2015-09-01

    The character of the bridged hydrogen atom (Hb) of B2H6 has become a hot issue in recent years. In this work, the complexes B2H6 · · · NH3, B2H2X4 · · · nNH3 (n = 1, 2) and 2HF · · · B2H2X4 · · · 2NH3 (X = Cl, Br, I) were constructed and studied based on the M06-2X calculations to investigate how to enhance the Hb · · · N hydrogen-bonded interaction. When the terminal hydrogen atoms (Ht) of B2H6 were replaced by X (X = Cl, Br, I) atoms, the Hb · · · N hydrogen bond were strengthened. According to the electrostatic potentials in B2H2X4, two HF molecules were added to the interspace of the B-H-B-H four-membered ring of the B2H2X4 · · · 2NH3 complexes, and H · · · X hydrogen bond formed, resulting in further enhancing effect of Hb · · · N hydrogen bond. As a result, the positive cooperative effect of Hb · · · N hydrogen bond and H · · · X hydrogen bond do enhance the interactions of each other. The two measures not only enhance the strength of Hb · · · N hydrogen bond, but also achieve the goal to make the Hb · · · N hydrogen bond perpendicular to B · · · B direction.

  15. Compact solid source of hydrogen gas

    Science.gov (United States)

    Kravitz, Stanley H.; Hecht, Andrew M.; Sylwester, Alan P.; Bell, Nelson S.

    2004-06-08

    A compact solid source of hydrogen gas, where the gas is generated by contacting water with micro-disperse particles of sodium borohydride in the presence of a catalyst, such as cobalt or ruthenium. The micro-disperse particles can have a substantially uniform diameter of 1-10 microns, and preferably about 3-5 microns. Ruthenium or cobalt catalytic nanoparticles can be incorporated in the micro-disperse particles of sodium borohydride, which allows a rapid and complete reaction to occur without the problems associated with caking and scaling of the surface by the reactant product sodium metaborate. A closed loop water management system can be used to recycle wastewater from a PEM fuel cell to supply water for reacting with the micro-disperse particles of sodium borohydride in a compact hydrogen gas generator. Capillary forces can wick water from a water reservoir into a packed bed of micro-disperse fuel particles, eliminating the need for using an active pump.

  16. Interaction between an icosahedron Li(13) cluster and a graphene layer doped with a hydrogen atom.

    Science.gov (United States)

    Rangel, Eduardo; Vázquez, Gerardo; Magaña, Fernando; Sansores, Enrique

    2012-12-01

    It is known that graphene reacts with atomic hydrogen to form a hydrogenated sheet of graphene. In order to understand the nature of the interaction between hydrogen and lithium in hydrogenated samples, we have carried out first principle calculations. Density functional theory and molecular dynamics were used to study the interaction between an icosahedron Li(13) cluster, and a graphene layer doped with a hydrogen atom. It was found that a hydrogen atom is levitated from the graphene layer and absorbed into the cluster of Li at 300 K and atmospheric pressure, with a binding energy far exceeding that of the adsorption energy of a hydrogen atom on the graphene layer.

  17. Graphene oxide/metal nanocrystal multilaminates as the atomic limit for safe and selective hydrogen storage.

    Science.gov (United States)

    Cho, Eun Seon; Ruminski, Anne M; Aloni, Shaul; Liu, Yi-Sheng; Guo, Jinghua; Urban, Jeffrey J

    2016-02-23

    Interest in hydrogen fuel is growing for automotive applications; however, safe, dense, solid-state hydrogen storage remains a formidable scientific challenge. Metal hydrides offer ample storage capacity and do not require cryogens or exceedingly high pressures for operation. However, hydrides have largely been abandoned because of oxidative instability and sluggish kinetics. We report a new, environmentally stable hydrogen storage material constructed of Mg nanocrystals encapsulated by atomically thin and gas-selective reduced graphene oxide (rGO) sheets. This material, protected from oxygen and moisture by the rGO layers, exhibits exceptionally dense hydrogen storage (6.5 wt% and 0.105 kg H2 per litre in the total composite). As rGO is atomically thin, this approach minimizes inactive mass in the composite, while also providing a kinetic enhancement to hydrogen sorption performance. These multilaminates of rGO-Mg are able to deliver exceptionally dense hydrogen storage and provide a material platform for harnessing the attributes of sensitive nanomaterials in demanding environments.

  18. ESR studies of spin-polarized atomic hydrogen using a 114-GHz heterodyne spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Statt, B.W.; Hardy, W.N.; Berlinsky, A.J.; Klein, E.

    1985-12-01

    Spin-polarized atomic hydrogen (Harrow-down) gas has been studied using electron spin resonance (ESR) techniques at low temperatures. The ESR apparatus and consequent data analysis required for accurate quantitative results are described in detail. Crucial to the data analysis is the ability to confine the sample of Harrow-down gas inside a liquid helium-coated microwave cavity where the magnetic field and temperature are constant. Results obtained so far are reported, which include the first detailed study of the one-body surface relaxation rate due to microscopic magnetic impurities in the cell walls.

  19. Nanosecond pulsed humid Ar plasma jet in air: shielding, discharge characteristics and atomic hydrogen production

    Science.gov (United States)

    Yatom, Shurik; Luo, Yuchen; Xiong, Qing; Bruggeman, Peter J.

    2017-10-01

    Gas phase non-equilibrium plasmas jets containing water vapor are of growing interest for many applications. In this manuscript, we report a detailed study of an atmospheric pressure nanosecond pulsed Ar  +  0.26% H2O plasma jet. The plasma jet operates in an atmospheric pressure air surrounding but is shielded with a coaxial argon flow to limit the air diffusion into the jet effluent core. The jet impinges on a metal plate electrode and produces a stable plasma filament (transient spark) between the needle electrode in the jet and the metal plate. The stable plasma filament is characterized by spatially and time resolved electrical and optical diagnostics. This includes Rayleigh scattering, Stark broadening of the hydrogen Balmer lines and two-photon absorption laser induced fluorescence (TaLIF) to obtain the gas temperature, the electron density and the atomic hydrogen density respectively. Electron densities and atomic hydrogen densities up to 5 × 1022 m-3 and 2 × 1022 m-3 have been measured. This shows that atomic hydrogen is one of the main species in high density Ar-H2O plasmas. The gas temperature does not exceed 550 K in the core of the plasma. To enable in situ calibration of the H TaLIF at atmospheric pressure a previously published O density calibration scheme is extended to include a correction for the line profiles by including overlap integrals as required by H TaLIF. The line width of H TaLIF, due to collision broadening has the same trend as the neutral density obtained by Rayleigh scattering. This suggests the possibility to use this technique to in situ probe neutral gas densities.

  20. An su(1, 1) algebraic method for the hydrogen atom

    Energy Technology Data Exchange (ETDEWEB)

    MartInez-y-Romero, R P [Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, Apartado Postal 50-542, Mexico City 04510 DF (Mexico); Nunez-Yepez, H N [Departamento de FIsica, Universidad Autonoma Metropolitana Unidad Iztapalapa, Apartado Postal 55-534, CP 09340, Iztapalapa DF (Germany); Salas-Brito, A L [Laboratorio de Sistemas Dinamicos, Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana Unidad Azcapotzalco, Apartado Postal 21-267, CP 04000, Coyoacan DF (Mexico)

    2005-10-07

    An algebraic solution for the hydrogen atom analogous to the one recently proposed to solve the relativistic version of the system is presented. We add to the usual radial description of the problem an additional angular variable and an associated operator which can be considered as part of an su(1, 1) Lie algebra. The operators of the algebra define radial ladder operator relating the eigenfunctions of the system in unit steps of the principal quantum number. We conclude that the radial bound states of the hydrogen atom in our extended configuration space can be regarded as spanning the minimal M representation of the su(1, 1) Lie algebra. The method can also be extended to solve the s-wave Morse problem and the three-dimensional harmonic oscillator.

  1. Hydrogen-Enhanced Natural Gas Vehicle Program

    Energy Technology Data Exchange (ETDEWEB)

    Hyde, Dan; Collier, Kirk

    2009-01-22

    The project objective is to demonstrate the viability of HCNG fuel (30 to 50% hydrogen by volume and the remainder natural gas) to reduce emissions from light-duty on-road vehicles with no loss in performance or efficiency. The City of Las Vegas has an interest in alternative fuels and already has an existing hydrogen refueling station. Collier Technologies Inc (CT) supplied the latest design retrofit kits capable of converting nine compressed natural gas (CNG) fueled, light-duty vehicles powered by the Ford 5.4L Triton engine. CT installed the kits on the first two vehicles in Las Vegas, trained personnel at the City of Las Vegas (the City) to perform the additional seven retrofits, and developed materials for allowing other entities to perform these retrofits as well. These vehicles were used in normal service by the City while driver impressions, reliability, fuel efficiency and emissions were documented for a minimum of one year after conversion. This project has shown the efficacy of operating vehicles originally designed to operate on compressed natural gas with HCNG fuel incorporating large quantities of exhaust gas recirculation (EGR). There were no safety issues experienced with these vehicles. The only maintenance issue in the project was some rough idling due to problems with the EGR valve and piping parts. Once the rough idling was corrected no further maintenance issues with these vehicles were experienced. Fuel economy data showed no significant changes after conversion even with the added power provided by the superchargers that were part of the conversions. Driver feedback for the conversions was very favorable. The additional power provided by the HCNG vehicles was greatly appreciated, especially in traffic. The drivability of the HCNG vehicles was considered to be superior by the drivers. Most of the converted vehicles showed zero oxides of nitrogen throughout the life of the project using the State of Nevada emissions station.

  2. Off-diagonal geometric phase of atom-electron coupling in hydrogen atom

    OpenAIRE

    Zhu, Guo-Qiang

    2009-01-01

    In this paper, the off-diagonal geometric phase of thermal state in hydrogen atom under the effects of external magnetic field is considered. Increasing temperature tends to suppress the off-diagonal geometric phase, including 1-order and 2-order cases. On the other hand, the relationship between the geometric phase and external magnetic field is discussed.

  3. Non-Hydrogenic Rydberg Atoms in Magnetic Fields

    OpenAIRE

    P. A., DANDO; T. S., MONTEIRO; W., JANS; W., SCHWEIZER; Department of Mathematics, Royal Holloway, University of London; Lehrstuhl fur Theoretische Astrophysik, University Tubingen

    1994-01-01

    The classical and quantal dynamics of non-hydrogenic Rydberg atoms in magnetic fields are investigated. Previous attempts to infer classical behaviour from quantum properties produced conflicting results: at low scaled energies (ε=-0.5) the nearest-neighbour statistics (NNS) were found to be at the chaotic (Wigner) limit while quantum phase-space distributions suggested a high degree of regularity. Here the classical limit is investigated directly by solving the equations of motion of the Dia...

  4. Dirac equation in noncommutative space for hydrogen atom

    Energy Technology Data Exchange (ETDEWEB)

    Adorno, T.C., E-mail: tadorno@nonada.if.usp.b [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, CEP 05508-090 Sao Paulo, SP (Brazil); Baldiotti, M.C., E-mail: baldiott@fma.if.usp.b [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, CEP 05508-090 Sao Paulo, SP (Brazil); Chaichian, M., E-mail: Masud.Chaichian@helsinki.f [Department of Physics, University of Helsinki and Helsinki Institute of Physics, PO Box 64, FIN-00014 Helsinki (Finland); Gitman, D.M., E-mail: gitman@dfn.if.usp.b [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, CEP 05508-090 Sao Paulo, SP (Brazil); Tureanu, A., E-mail: Anca.Tureanu@helsinki.f [Department of Physics, University of Helsinki and Helsinki Institute of Physics, PO Box 64, FIN-00014 Helsinki (Finland)

    2009-11-30

    We consider the energy levels of a hydrogen-like atom in the framework of theta-modified, due to space noncommutativity, Dirac equation with Coulomb field. It is shown that on the noncommutative (NC) space the degeneracy of the levels 2S{sub 1/2}, 2P{sub 1/2} and 2P{sub 3/2} is lifted completely, such that new transition channels are allowed.

  5. Relative Fisher information of hydrogen-like atoms

    Science.gov (United States)

    Yamano, Takuya

    2018-01-01

    The relative Fisher information is a measure of distance between two probability densities. We calculate it for the electron orbitals of hydrogen-like atoms by taking 1s state as the reference orbital. We find that the measure decreases as the principal quantum number increases, indicating that the electron cloud of excited states in radial direction becomes close to the one of 1s orbital.

  6. Ground-state structures of atomic metallic hydrogen.

    Science.gov (United States)

    McMahon, Jeffrey M; Ceperley, David M

    2011-04-22

    Ab initio random structure searching using density functional theory is used to determine the ground-state structures of atomic metallic hydrogen from 500 GPa to 5 TPa. Including proton zero-point motion within the harmonic approximation, we estimate that molecular hydrogen dissociates into a monatomic body-centered tetragonal structure near 500 GPa (r(s)=1.23) that remains stable to 1 TPa (r(s)=1.11). At higher pressures, hydrogen stabilizes in an …ABCABC… planar structure that is similar to the ground state of lithium, but with a different stacking sequence. With increasing pressure, this structure compresses to the face-centered cubic lattice near 3.5 TPa (r(s)=0.92).

  7. The atomic hydrogen cloud in the saturnian system

    Science.gov (United States)

    Tseng, W.-L.; Johnson, R. E.; Ip, W.-H.

    2013-09-01

    The importance of Titan's H torus shaped by solar radiation pressure and of hydrogen atoms flowing out of Saturn's atmosphere in forming the broad hydrogen cloud in Saturn's magnetosphere is still debated. Since the Saturnian system also contains a water product torus which originates from the Enceladus plumes, the icy ring particles, and the inner icy satellites, as well as Titan's H2 torus, we have carried out a global investigation of the atomic hydrogen cloud taking into account all sources. We show that the velocity and angle distributions of the hot H ejected from Saturn's atmosphere following electron-impact dissociation of H2 are modified by collisions with the ambient atmospheric H2 and H. This in turn affects the morphology of the escaping hydrogen from Saturn, as does the morphology of the ionospheric electron distribution. Although an exact agreement with the Cassini observations is not obtained, our simulations show that H directly escaping from Titan is the dominant contributor in the outer magnetosphere. Of the total number of H observed by Cassini from 1 to 5RS, ∼5.7×1034, our simulations suggest ∼20% is from dissociation in the Enceladus torus, ∼5-10% is from dissociation of H2 in the atmosphere of the main rings, and ∼50% is from Titan's H torus, implying that ∼20% comes from Saturn atmosphere.

  8. Pressure of a partially ionized hydrogen gas : numerical results from exact low temperature expansions

    OpenAIRE

    Alastuey, Angel; Ballenegger, Vincent

    2010-01-01

    8 pages; International audience; We consider a partially ionized hydrogen gas at low densities, where it reduces almost to an ideal mixture made with hydrogen atoms in their ground-state, ionized protons and ionized electrons. By performing systematic low-temperature expansions within the physical picture, in which the system is described as a quantum electron-proton plasma interacting via the Coulomb potential, exact formulae for the first five leading corrections to the ideal Saha equation ...

  9. Transport Properties of Spin-Polarized Atomic Hydrogen Using Generalized Scattering Theory

    Science.gov (United States)

    Joudeh, B. R.; Sandouqa, A. S.

    2018-02-01

    Our results for the scattering and thermophysical properties of spin-polarized atomic hydrogen (H{\\downarrow }) have been presented in the temperature range 0.01-10 K using the Galitskii-Migdal-Feynman formalism. These results include the quantum second virial coefficient, the average total and viscosity cross sections, the viscosity, the diffusion coefficient, and the thermal conductivity. The calculations have been undertaken using three triplet-state potentials: Morse-type, Silvera and Born-Oppenheimer potentials. The Morse potential is less attractive and very simple, but less accurate to describe spin-polarized atomic hydrogen. That explains the differences between it and the other two potentials, which are clearly better. From the results of the average total cross sections, it is concluded the H{\\downarrow } remains a gas even at low temperature. The viscosity, the thermal conductivity, and the diffusion coefficients of H{\\downarrow } increase in all cases with increasing temperature.

  10. THE DYNAMICS OF HYDROGEN ATOM ABSTRACTION FROM POLYATOMIC MOLECULES.

    Energy Technology Data Exchange (ETDEWEB)

    LIU,X.; SUITS,A.G.

    2002-11-21

    The hydrogen atom abstraction reaction is an important fundamental process that is extensively involved in atmospheric and combustion chemistry. The practical significance of this type of reaction with polyatomic hydrocarbons is manifest, which has led to many kinetics studies. The detailed understanding of these reactions requires corresponding dynamics studies. However, in comparison to the A + HX {radical} AH + X reactions, the study of the dynamics of A + HR {yields} AH + R reactions is much more difficult, both experimentally and theoretically (here and in the following, A stands for an atom, X stands for a halogen atom, and R stands for a polyatomic hydrocarbon radical). The complication stems from the structured R, in contrast to the structureless X. First of all, there are many internal degrees of freedom in R that can participate in the reaction. In addition, there are different carbon sites from which an H atom can be abstracted, and the dynamics are correspondingly different; there are also multiple identical carbon sites in HR and in the picture of a local reaction, there exist competitions between neighboring H atoms, and so on. Despite this complexity, there have been continuing efforts to obtain insight into the dynamics of these reactions. In this chapter, some examples are presented, including the reactions of ground state H, Cl, and O atoms, with particular focus on our recent work using imaging to obtain the differential cross sections for these reactions.

  11. Reactions of butadiyne. 1: The reaction with hydrogen atoms

    Science.gov (United States)

    Schwanebeck, W.; Warnatz, J.

    1984-01-01

    The reaction of hydrogen (H) atoms with butadiene (C4H2) was studied at room temperature in a pressure range between w mbar and 10 mbar. The primary step was an addition of H to C4H2 which is in its high pressure range at p 1 mbar. Under these conditions the following addition of a second H atom lies in the transition region between low and high pressure range. Vibrationally excited C4H4 can be deactivated to form buten-(1)-yne-(3)(C4H4) or decomposes into two C2H2 molecules. The rate constant at room temperature for primary step is given. The second order rate constant for the consumption of buten-(1)-yne-(3) is an H atom excess at room temperature is given.

  12. Coherent Atom Optics with fast metastable rare gas atoms

    Science.gov (United States)

    Grucker, J.; Baudon, J.; Karam, J.-C.; Perales, F.; Bocvarski, V.; Vassilev, G.; Ducloy, M.

    2006-12-01

    Coherent atom optics experiments making use of an ultra-narrow beam of fast metastable atoms generated by metastability exchange are reported. The transverse coherence of the beam (coherence radius of 1.7 μm for He*, 1.2 μm for Ne*, 0.87 μm for Ar*) is demonstrated via the atomic diffraction by a non-magnetic 2μm-period reflection grating. The combination of the non-scalar van der Waals (vdW) interaction with the Zeeman interaction generated by a static magnetic field gives rise to "vdW-Zeeman" transitions among Zeeman sub-levels. Exo-energetic transitions of this type are observed with Ne*(3P2) atoms traversing a copper micro-slit grating. They can be used as a tunable beam splitter in an inelastic Fresnel bi-prism atom interferometer.

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

    NARCIS (Netherlands)

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

    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

  14. Impact of hydrogen insertion on vehicular natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Strangueto, Karina Maretti; Silva, Ennio Peres da [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. of Mechanical Engineering. Energy Dept.], Email: karinakms@fem.unicamp.br

    2010-07-01

    This article aims to analyze the possibility of insertion of hydrogen in the vehicular natural gas or even the insertion of the hydrogen in the compressed natural gas used in Brazil. For the production of this hydrogen, the spilled turbinable energy from Itaipu would be harnessed. The calculation of production can be extended to other power plants which are close to the natural gas pipelines, where the hydrogen would be introduced. Then, it was analyzed the consumption of natural gas in vehicles in Brazil, the regulation of transportation, the sales of compressed natural gas to fuelling station, the specifications that the piped gas should follow to be sold, and how much hydrogen could be accepted in the mix. (author)

  15. Signatures of a quantum diffusion limited hydrogen atom tunneling reaction.

    Science.gov (United States)

    Balabanoff, Morgan E; Ruzi, Mahmut; Anderson, David T

    2017-12-20

    We are studying the details of hydrogen atom (H atom) quantum diffusion in highly enriched parahydrogen (pH 2 ) quantum solids doped with chemical species in an effort to better understand H atom transport and reactivity under these conditions. In this work we present kinetic studies of the 193 nm photo-induced chemistry of methanol (CH 3 OH) isolated in solid pH 2 . Short-term irradiation of CH 3 OH at 1.8 K readily produces CH 2 O and CO which we detect using FTIR spectroscopy. The in situ photochemistry also produces CH 3 O and H atoms which we can infer from the post-photolysis reaction kinetics that display significant CH 2 OH growth. The CH 2 OH growth kinetics indicate at least three separate tunneling reactions contribute; (i) reactions of photoproduced CH 3 O with the pH 2 host, (ii) H atom reactions with the CH 2 O photofragment, and (iii) long-range migration of H atoms and reaction with CH 3 OH. We assign the rapid CH 2 OH growth to the following CH 3 O + H 2 → CH 3 OH + H → CH 2 OH + H 2 two-step sequential tunneling mechanism by conducting analogous kinetic measurements using deuterated methanol (CD 3 OD). By performing photolysis experiments at 1.8 and 4.3 K, we show the post-photolysis reaction kinetics change qualitatively over this small temperature range. We use this qualitative change in the reaction kinetics with temperature to identify reactions that are quantum diffusion limited. While these results are specific to the conditions that exist in pH 2 quantum solids, they have direct implications on the analogous low temperature H atom tunneling reactions that occur on metal surfaces and on interstellar grains.

  16. Identification of new, well-populated amino-acid sidechain rotamers involving hydroxyl-hydrogen atoms and sulfhydryl-hydrogen atoms

    Directory of Open Access Journals (Sweden)

    Agard David A

    2008-10-01

    Full Text Available Abstract Background An important element in homology modeling is the use of rotamers to parameterize the sidechain conformation. Despite the many libraries of sidechain rotamers that have been developed, a number of rotamers have been overlooked, due to the fact that they involve hydrogen atoms. Results We identify new, well-populated rotamers that involve the hydroxyl-hydrogen atoms of Ser, Thr and Tyr, and the sulfhydryl-hydrogen atom of Cys, using high-resolution crystal structures ( Conclusion Knowledge of these new rotamers will improve the evaluation of hydrogen-bonding networks in protein structures.

  17. Quantitative analysis of hydrogen in SiO2/SiN/SiO2 stacks using atom probe tomography

    Directory of Open Access Journals (Sweden)

    Yorinobu Kunimune

    2016-04-01

    Full Text Available We have demonstrated that it is possible to reproducibly quantify hydrogen concentration in the SiN layer of a SiO2/SiN/SiO2 (ONO stack structure using ultraviolet laser-assisted atom probe tomography (APT. The concentration of hydrogen atoms detected using APT increased gradually during the analysis, which could be explained by the effect of hydrogen adsorption from residual gas in the vacuum chamber onto the specimen surface. The amount of adsorbed hydrogen in the SiN layer was estimated by analyzing another SiN layer with an extremely low hydrogen concentration (<0.2 at. %. Thus, by subtracting the concentration of adsorbed hydrogen, the actual hydrogen concentration in the SiN layer was quantified as approximately 1.0 at. %. This result was consistent with that obtained by elastic recoil detection analysis (ERDA, which confirmed the accuracy of the APT quantification. The present results indicate that APT enables the imaging of the three-dimensional distribution of hydrogen atoms in actual devices at a sub-nanometer scale.

  18. Asymptotics of Rydberg states for the hydrogen atom

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, L.E. [Virginia Univ., Charlottesville, VA (United States). Dept. of Mathematics; Villegas-Blas, C. [Universidad Nacional Autonoma de Mexico, Instituto de Matematicas, Unidad Cuernavaca, A. P. 273-3 Admon. 3, Cuernavaca Morelos 62251 (Mexico)

    1997-08-01

    The asymptotics of Rydberg states, i.e., highly excited bound states of the hydrogen atom Hamiltonian, and various expectations involving these states are investigated. We show that suitable linear combinations of these states, appropriately rescaled and regarded as functions either in momentum space or configuration space, are highly concentrated on classical momentum space or configuration space Kepler orbits respectively, for large quantum numbers. Expectations of momentum space or configuration space functions with respect to these states are related to time-averages of these functions over Kepler orbits. (orig.)

  19. 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

  20. Gas phase detection of the NH-P hydrogen bond and importance of secondary interactions

    DEFF Research Database (Denmark)

    Møller, Kristian Holten; Hansen, Anne Schou; Kjærgaard, Henrik Grum

    2015-01-01

    We have observed the NH···P hydrogen bond in a gas phase complex. The bond is identified in the dimethylamine-trimethylphosphine complex by a red shift of the fundamental NH-stretching frequency observed using Fourier transform infrared spectroscopy (FT-IR). On the basis of the measured NH......-stretching frequency red shifts, we find that P is a hydrogen bond acceptor atom similar in strength to S. Both are stronger acceptors than O and significantly weaker acceptors than N. The hydrogen bond angle, ∠NHP, is found to be very sensitive to the functional employed in density functional theory (DFT......) optimizations of the complex and is a possible parameter to assess the quality of DFT functionals. Natural bonding orbital (NBO) energies and results from the topological methods atoms in molecules (AIM) and noncovalent interactions (NCI) indicate that the sensitivity is caused by the weakness of the hydrogen...

  1. Massive stars formed in atomic hydrogen reservoirs: H i observations of gamma-ray burst host galaxies

    DEFF Research Database (Denmark)

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

    2015-01-01

    Long gamma-ray bursts (GRBs), among the most energetic events in the Universe, are explosions of massive and short-lived stars, so they pinpoint locations of recent star formation. However, several GRB host galaxies have recently been found to be deficient in molecular gas (H2), believed to be th......Long gamma-ray bursts (GRBs), among the most energetic events in the Universe, are explosions of massive and short-lived stars, so they pinpoint locations of recent star formation. However, several GRB host galaxies have recently been found to be deficient in molecular gas (H2), believed......, implying high levels of atomic hydrogen (HI), which suggests that the connection between atomic gas and star formation is stronger than previously thought. In this case, it is possible that star formation is directly fuelled by atomic gas (or that the H1-to-H2 conversion is very efficient, which rapidly...

  2. Hot hydrogen atom reactions moderated by H2 and He

    Science.gov (United States)

    Aronowitz, S.; Scattergood, T.; Flores, J.; Chang, S.

    1986-01-01

    Photolysis experiments were performed on the H2-CD4-NH3 and He-CD4-NH3 systems. The photolysis (1849 A) involved only NH3. Mixtures of H2:CD4:NH3 included all combinations of the ratios (200,400,800):(10,20,40):4. Two He:CD4:NH3 mixtures were examined where the ratios equalled the combinations 100:(10,20):4. Abstraction of a D from CD4 by the photolytically produced hot hydrogen from ammonia was monitored by mass spectrometric determination of HD. Both experiment and semiempirical hot-atom theory show that H2 is a very poor thermalizer of hot hydrogens with excess kinetic energy of about 2 eV. Applications of the hard-sphere collision model to the H2-CD4-NH3 system resulted in predicted ratios of net HD production to NH3 decomposition that were two orders of magnitude smaller than the experimental ratios. On the other hand, helium is found to be a very efficient thermalizer; here, the classical model yields reasonable agreement with experiments. Application of a semiempirical hot-atom program gave quantitative agreement with experiment for either system.

  3. Development Of A Centrifugal Hydrogen Pipeline Gas Compressor

    Energy Technology Data Exchange (ETDEWEB)

    Di Bella, Francis A. [Concepts NREC, White River Junction, VY (United States)

    2015-04-16

    Concepts NREC (CN) has completed a Department of Energy (DOE) sponsored project to analyze, design, and fabricate a pipeline capacity hydrogen compressor. The pipeline compressor is a critical component in the DOE strategy to provide sufficient quantities of hydrogen to support the expected shift in transportation fuels from liquid and natural gas to hydrogen. The hydrogen would be generated by renewable energy (solar, wind, and perhaps even tidal or ocean), and would be electrolyzed from water. The hydrogen would then be transported to the population centers in the U.S., where fuel-cell vehicles are expected to become popular and necessary to relieve dependency on fossil fuels. The specifications for the required pipeline hydrogen compressor indicates a need for a small package that is efficient, less costly, and more reliable than what is available in the form of a multi-cylinder, reciprocating (positive displacement) compressor for compressing hydrogen in the gas industry.

  4. Emission of fast hydrogen atoms at a plasma–solid interface in a low density plasma containing noble gases

    Science.gov (United States)

    Marchuk, O.; Brandt, C.; Pospieszczyk, A.; Reinhart, M.; Brezinsek, S.; Unterberg, B.; Dickheuer, S.

    2018-01-01

    The source of the broad radiation of fast hydrogen atoms in plasmas containing noble gases remains one of the most discussed problems relating to plasma–solid interface. In this paper, we present a detailed study of Balmer lines emission generated by fast hydrogen and deuterium atoms in an energy range between 40 and 300 eV in a linear magnetised plasma. The experiments were performed in gas mixtures containing hydrogen or deuterium and one of the noble gases (He, Ne, Ar, Kr or Xe). In the low-pressure regime (0.01–0.1 Pa) of plasma operation emission is detected by using high spectral and spatial resolution spectrometers at different lines-of-sight for different target materials (C, Fe, Rh, Pd, Ag and W). We observed the spatial evolution for H α , H β and H γ lines with a resolution of 50 μm in front of the targets, proving that emission is induced by reflected atoms only. The strongest radiation of fast atoms was observed in the case of Ar–D or Ar–H discharges. It is a factor of five less in Kr–D plasma and an order of magnitude less in other rare gas mixture plasmas. First, the present work shows that the maximum of emission is achieved for the kinetic energy of 70–120 eV/amu of fast atoms. Second, the emission profile depends on the target material as well as surface characteristics such as the particle reflection, e.g. angular and energy distribution, and the photon reflectivity. Finally, the source of emission of fast atoms is narrowed down to two processes: excitation caused by collisions with noble gas atoms in the ground state, and excitation transfer between the metastable levels of argon and the excited levels of hydrogen or deuterium.

  5. Modeling hydrogen storage in boron-substituted graphene decorated with potassium metal atoms

    CSIR Research Space (South Africa)

    Tokarev, A

    2015-03-01

    Full Text Available Boron-substituted graphene decorated with potassium metal atoms was considered as a novel material for hydrogen storage. Density functional theory calculations were used to model key properties of the material, such as geometry, hydrogen packing...

  6. The ground state properties of spin-aligned atomic hydrogen, deuterium, and tritium

    Science.gov (United States)

    Etters, R. D.; Dugan, J. V., Jr.; Palmer, R. W.

    1975-01-01

    The internal energy, pressure, and compressibility of ground-state, spin-aligned atomic hydrogen, deuterium, and tritium are calculated assuming that all pair interactions occur via the atomic triplet (spin-aligned) potential. The conditions required to obtain atomic hydrogen and its isotopes in bulk are discussed; such a development would be of value in propulsion systems because of the light mass and energetic recombination of atomic hydrogen. Results show that atomic triplet hydrogen and deuterium remain gaseous at 0 K, and that tritium forms a liquid with a binding energy of approximately -0.75 K per atom at a molar volume of 130 cu cm per mole. The pair distribution function for these systems is calculated, and the predicted superfluid behavior of atomic triplet hydrogen and tritium is briefly discussed.

  7. Estimation of hepatic blood flow by hydrogen gas clearance

    NARCIS (Netherlands)

    Gouma, D. J.; Coelho, J. C.; Schlegel, J.; Fisher, J. D.; Li, Y. F.; Moody, F. G.

    1986-01-01

    The hydrogen gas clearance technique was evaluated to estimate regional hepatic blood flow. Initially, the H2 gas method was compared to the indocyanine green clearance in mini pigs. The blood flow measured by the H2 gas method (0.49 +/- 0.03 ml/min/gm) was only 39% of the calculated blood flow by

  8. Adsorption process to recover hydrogen from feed gas mixtures having low hydrogen concentration

    Science.gov (United States)

    Golden, Timothy Christopher; Weist, Jr., Edward Landis; Hufton, Jeffrey Raymond; Novosat, Paul Anthony

    2010-04-13

    A process for selectively separating hydrogen from at least one more strongly adsorbable component in a plurality of adsorption beds to produce a hydrogen-rich product gas from a low hydrogen concentration feed with a high recovery rate. Each of the plurality of adsorption beds subjected to a repetitive cycle. The process comprises an adsorption step for producing the hydrogen-rich product from a feed gas mixture comprising 5% to 50% hydrogen, at least two pressure equalization by void space gas withdrawal steps, a provide purge step resulting in a first pressure decrease, a blowdown step resulting in a second pressure decrease, a purge step, at least two pressure equalization by void space gas introduction steps, and a repressurization step. The second pressure decrease is at least 2 times greater than the first pressure decrease.

  9. Dirac equation in very special relativity for hydrogen atom

    Directory of Open Access Journals (Sweden)

    R.V. Maluf

    2014-11-01

    Full Text Available In this work, we study the modified Dirac equation in the framework of very special relativity (VSR. The low-energy regime is accessed and the nonrelativistic Hamiltonian is obtained. It turns out that this Hamiltonian is similar to that achieved from the Standard Model Extension (SME via coupling of the spinor field to a Lorentz-violating term, but new features arise inherited from the non-local character of the VSR. In addition, the implications of the VSR-modified Lorentz symmetry on the spectrum of a hydrogen atom are determined by calculating the first-order energy corrections in the context of standard quantum mechanics. Among the results, we highlight that the modified Hamiltonian provides non-vanishing corrections which lift the degeneracy of the energy levels and allow us to find an upper bound upon the VSR-parameter.

  10. Entropy and complexity analysis of hydrogenic Rydberg atoms

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Rosa, S. [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain); Departamento de Fisica Aplicada II, Universidad de Sevilla, 41012-Sevilla (Spain); Toranzo, I. V.; Dehesa, J. S. [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain); Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, 18071-Granada (Spain); Sanchez-Moreno, P. [Instituto Carlos I de Fisica Teorica y Computacional, Universidad de Granada, 18071-Granada (Spain); Departamento de Matematica Aplicada, Universidad de Granada, 18071-Granada (Spain)

    2013-05-15

    The internal disorder of hydrogenic Rydberg atoms as contained in their position and momentum probability densities is examined by means of the following information-theoretic spreading quantities: the radial and logarithmic expectation values, the Shannon entropy, and the Fisher information. As well, the complexity measures of Cramer-Rao, Fisher-Shannon, and Lopez Ruiz-Mancini-Calvet types are investigated in both reciprocal spaces. The leading term of these quantities is rigorously calculated by use of the asymptotic properties of the concomitant entropic functionals of the Laguerre and Gegenbauer orthogonal polynomials which control the wavefunctions of the Rydberg states in both position and momentum spaces. The associated generalized Heisenberg-like, logarithmic and entropic uncertainty relations are also given. Finally, application to linear (l= 0), circular (l=n- 1), and quasicircular (l=n- 2) states is explicitly done.

  11. Low cost hydrogen/novel membrane technology for hydrogen separation from synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Baker, R.W.; Bell, C.M.; Chow, P.; Louie, J.; Mohr, J.M.; Peinemann, K.V.; Pinnau, I.; Wijmans, J.G.; Gottschlich, D.E.; Roberts, D.L.

    1990-10-01

    The production of hydrogen from synthesis gas made by gasification of coal is expensive. The separation of hydrogen from synthesis gas is a major cost element in the total process. In this report we describe the results of a program aimed at the development of membranes and membrane modules for the separation and purification of hydrogen from synthesis gas. The performance properties of the developed membranes were used in an economic evaluation of membrane gas separation systems in the coal gasification process. Membranes tested were polyetherimide and a polyamide copolymer. The work began with an examination of the chemical separations required to produce hydrogen from synthesis gas, identification of three specific separations where membranes might be applicable. A range of membrane fabrication techniques and module configurations were investigated to optimize the separation properties of the membrane materials. Parametric data obtained were used to develop the economic comparison of processes incorporating membranes with a base-case system without membranes. The computer calculations for the economic analysis were designed and executed. Finally, we briefly investigated alternative methods of performing the three separations in the production of hydrogen from synthesis gas. The three potential opportunities for membranes in the production of hydrogen from synthesis gas are: (1) separation of hydrogen from nitrogen as the final separation in a air-blown or oxygen-enriched air-blown gasification process, (2) separation of hydrogen from carbon dioxide and hydrogen sulfide to reduce or eliminate the conventional ethanolamine acid gas removal unit, and (3) separation of hydrogen and/or carbon dioxide form carbon monoxide prior to the shift reactor to influence the shift reaction. 28 refs., 54 figs., 40 tabs.

  12. Gas-phase hydrogenation influence on defect behavior in titanium-based hydrogen-storage material

    Directory of Open Access Journals (Sweden)

    Roman S. Laptev

    2017-02-01

    Full Text Available Titanium and its alloys are promising materials for hydrogen storage. However, hydrogen penetration accompanies the exploitation of hydrogen storage alloys. In particular, hydrogen penetration and accumulation in titanium alloys changes their mechanical properties. Therefore, the research works of such materials are mainly focused on improving the reversibility of hydrogen absorption-liberation processes, increasing the thermodynamic characteristics of the alloys, and augmenting their hydrogen storage capacity. In the process of hydrogenation-dehydrogenation, the formed defects both significantly reduce hydrogen storage capacity and can also be used to create effective traps for hydrogen. Therefore, the investigation of hydrogen interaction with structural defects in titanium and its alloys is very important. The present work, the hydrogen-induced formation of defects in the alloys of commercially pure titanium under temperature gas-phase hydrogenation (873 K has studied by positron lifetime spectroscopy and Doppler broadening spectroscopy. Based on the evolution of positron annihilation parameters τf, τd, their corresponding intensities If, Id and relative changes of parameters S/S0 and W/W0, the peculiarities of hydrogen interaction with titanium lattice defects were investigated in a wide range of hydrogen concentrations from 0.8at% to 32.0at%.

  13. Passivation and alloying element retention in gas atomized powders

    Energy Technology Data Exchange (ETDEWEB)

    Heidloff, Andrew J.; Rieken, Joel R.; Anderson, Iver E.

    2017-12-05

    A method for gas atomization of a titanium alloy, nickel alloy, or other alumina (Al.sub.2O.sub.3)-forming alloy wherein the atomized particles are exposed as they solidify and cool in a very short time to multiple gaseous reactive agents for the in-situ formation of a passivation reaction film on the atomized particles wherein the reaction film retains a precursor halogen alloying element that is subsequently introduced into a microstructure formed by subsequent thermally processing of the atomized particles to improve oxidation resistance.

  14. Quantum dynamics of hydrogen atoms on graphene. II. Sticking

    Energy Technology Data Exchange (ETDEWEB)

    Bonfanti, Matteo, E-mail: matteo.bonfanti@unimi.it [Dipartimento di Chimica, Università degli Studi di Milano, v. Golgi 19, 20133 Milano (Italy); Jackson, Bret [Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003 (United States); Hughes, Keith H. [School of Chemistry, Bangor University, Bangor, Gwynedd LL57 2UW (United Kingdom); Burghardt, Irene [Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt/Main (Germany); Martinazzo, Rocco, E-mail: rocco.martinazzo@unimi.it [Dipartimento di Chimica, Università degli Studi di Milano, v. Golgi 19, 20133 Milano (Italy); Istituto di Scienze e Tecnologie Molecolari, Consiglio Nazionale delle Richerche, v. Golgi 19, 20133 Milano (Italy)

    2015-09-28

    Following our recent system-bath modeling of the interaction between a hydrogen atom and a graphene surface [Bonfanti et al., J. Chem. Phys. 143, 124703 (2015)], we present the results of converged quantum scattering calculations on the activated sticking dynamics. The focus of this study is the collinear scattering on a surface at zero temperature, which is treated with high-dimensional wavepacket propagations with the multi-configuration time-dependent Hartree method. At low collision energies, barrier-crossing dominates the sticking and any projectile that overcomes the barrier gets trapped in the chemisorption well. However, at high collision energies, energy transfer to the surface is a limiting factor, and fast H atoms hardly dissipate their excess energy and stick on the surface. As a consequence, the sticking coefficient is maximum (∼0.65) at an energy which is about one and half larger than the barrier height. Comparison of the results with classical and quasi-classical calculations shows that quantum fluctuations of the lattice play a primary role in the dynamics. A simple impulsive model describing the collision of a classical projectile with a quantum surface is developed which reproduces the quantum results remarkably well for all but the lowest energies, thereby capturing the essential physics of the activated sticking dynamics investigated.

  15. Hydrogen storage materials discovery via high throughput ball milling and gas sorption.

    Science.gov (United States)

    Li, Bin; Kaye, Steven S; Riley, Conor; Greenberg, Doron; Galang, Daniel; Bailey, Mark S

    2012-06-11

    The lack of a high capacity hydrogen storage material is a major barrier to the implementation of the hydrogen economy. To accelerate discovery of such materials, we have developed a high-throughput workflow for screening of hydrogen storage materials in which candidate materials are synthesized and characterized via highly parallel ball mills and volumetric gas sorption instruments, respectively. The workflow was used to identify mixed imides with significantly enhanced absorption rates relative to Li2Mg(NH)2. The most promising material, 2LiNH2:MgH2 + 5 atom % LiBH4 + 0.5 atom % La, exhibits the best balance of absorption rate, capacity, and cycle-life, absorbing >4 wt % H2 in 1 h at 120 °C after 11 absorption-desorption cycles.

  16. In situ ellipsometry study of atomic hydrogen etching of extreme ultraviolet induced carbon layers

    NARCIS (Netherlands)

    Chen, J. Q.; E. Louis,; Harmsen, R.; T. Tsarfati,; Wormeester, H.; van Kampen, M.; van Schaik, W.; van de Kruijs, R.; F. Bijkerk,

    2011-01-01

    Atomic hydrogen based etching is generally considered an efficient method for the removal of carbon films resulting from photo-induced hydrocarbon dissociation, as occurs in extreme ultraviolet (EUV) photolithography environments. The etch rate of atomic hydrogen for three different kinds of carbon

  17. Perturbation calculations of the interaction energies between non-bonded hydrogen atoms - Part 2

    NARCIS (Netherlands)

    Laidlaw, W.G.; Lekkerkerker, H.N.W.; Wieser, H.

    1971-01-01

    Calculations of the interaction energy between non-bonded hydrogen atoms in the fragments A—H---H'—A' for selected displacements of the hydrogen atoms enable one to evaluate corrections to the force field due to the non-bonded interactions and to discuss the changes in the stretching vibration

  18. Schrodinger Equation Solutions that Lead to the Solution for the Hydrogen Atom

    Science.gov (United States)

    Newhouse, Paul F.; McGill, K.C.

    2004-01-01

    Two exercises that would provide beginning quantum theory students with an introduction to more advanced quantum mechanical treatments, especially the hydrogen atom are given. The exercises are stepwise in difficulty, leading naturally to the full hydrogen atom development and greatly extend the pedagogy of most multidimensional Cartesian systems…

  19. Thermo-Gas Dynamics of Hydrogen Combustion and Explosion

    CERN Document Server

    Gelfand, Boris E; Medvedev, Sergey P; Khomik, Sergey V

    2012-01-01

    The potential of hydrogen as an important future energy source has generated fresh interest in the study of hydrogenous gas mixtures. Indeed, both its high caloricity and reactivity are unique properties, the latter underscoring safety considerations when handling such mixtures.   The present monograph is devoted to the various aspects of hydrogen combustion and explosion processes. In addition to theoretical and phenomenological considerations, this work also collates the results of many experiments from less well known sources. The text reviews the literature in this respect, thereby providing valuable information about the thermo-gas-dynamical parameters of combustion processes for selected experimental settings in a range of scientific and industrial applications.

  20. Convergent close-coupling approach to light and heavy projectile scattering on atomic and molecular hydrogen

    Science.gov (United States)

    Bray, I.; Abdurakhmanov, I. B.; Bailey, J. J.; Bray, A. W.; Fursa, D. V.; Kadyrov, A. S.; Rawlins, C. M.; Savage, J. S.; Stelbovics, A. T.; Zammit, M. C.

    2017-10-01

    The atomic hydrogen target has played a pivotal role in the development of quantum collision theory. The key complexities of computationally managing the countably infinite discrete states and the uncountably infinite continuum were solved by using atomic hydrogen as the prototype atomic target. In the case of positron or proton scattering the extra complexity of charge exchange was also solved using the atomic hydrogen target. Most recently, molecular hydrogen has been used successfully as a prototype molecule for developing the corresponding scattering theory. We concentrate on the convergent close-coupling computational approach to light projectiles, such as electrons and positrons, and heavy projectiles, such as protons and antiprotons, scattering on atomic and molecular hydrogen.

  1. Hydrogenation of acetylene on Si(100)-(2×1) with atomic hydrogen: evidence for quasi Eley Rideal chemistry

    Science.gov (United States)

    Yi, S. I.; Weinberg, W. H.

    1998-10-01

    The adsorption of atomic hydrogen on the Si(100)-(2×1) surface with pre-adsorbed acetylene has been studied. For exposures of atomic hydrogen less than 2 L, the clean Si dimers without coadsorbed acetylene react to form Si monohydride. With an exposure of 5 to 10 L of atomic hydrogen, acetylene-occupied Si dimers as well as the acetylene itself also react to form Si monohydride and ethylene, respectively. At much higher exposures the formation of ethyl and Si dihydride is observed. This sequence of reaction events is discussed within the context of a quasi Eley-Rideal reaction of atomic hydrogen with the surface species, i.e. the radical atomic hydrogen has a finite diffusion length on the surface prior to reaction or desorption. A modified Kisliuk adsorption model has been employed successfully to describe the rates of Si monohydride and ethylene formation at a surface temperature of 150 K as a function of both the initial acetylene coverage and the post-exposure of atomic hydrogen.

  2. 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.

  3. Hydrogen Gas Sensors Based on Semiconductor Oxide Nanostructures

    Science.gov (United States)

    Gu, Haoshuang; Wang, Zhao; Hu, Yongming

    2012-01-01

    Recently, the hydrogen gas sensing properties of semiconductor oxide (SMO) nanostructures have been widely investigated. In this article, we provide a comprehensive review of the research progress in the last five years concerning hydrogen gas sensors based on SMO thin film and one-dimensional (1D) nanostructures. The hydrogen sensing mechanism of SMO nanostructures and some critical issues are discussed. Doping, noble metal-decoration, heterojunctions and size reduction have been investigated and proved to be effective methods for improving the sensing performance of SMO thin films and 1D nanostructures. The effect on the hydrogen response of SMO thin films and 1D nanostructures of grain boundary and crystal orientation, as well as the sensor architecture, including electrode size and nanojunctions have also been studied. Finally, we also discuss some challenges for the future applications of SMO nanostructured hydrogen sensors. PMID:22778599

  4. Hydrogen Gas Sensors Based on Semiconductor Oxide Nanostructures

    Directory of Open Access Journals (Sweden)

    Yongming Hu

    2012-04-01

    Full Text Available Recently, the hydrogen gas sensing properties of semiconductor oxide (SMO nanostructures have been widely investigated. In this article, we provide a comprehensive review of the research progress in the last five years concerning hydrogen gas sensors based on SMO thin film and one-dimensional (1D nanostructures. The hydrogen sensing mechanism of SMO nanostructures and some critical issues are discussed. Doping, noble metal-decoration, heterojunctions and size reduction have been investigated and proved to be effective methods for improving the sensing performance of SMO thin films and 1D nanostructures. The effect on the hydrogen response of SMO thin films and 1D nanostructures of grain boundary and crystal orientation, as well as the sensor architecture, including electrode size and nanojunctions have also been studied. Finally, we also discuss some challenges for the future applications of SMO nanostructured hydrogen sensors.

  5. Symmetry-resolved spectroscopy by detection of a metastable hydrogen atom for investigating the doubly excited states of molecular hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Odagiri, Takeshi; Kumagai, Yoshiaki; Tanabe, Takehiko; Nakano, Motoyoshi; Kouchi, Noriyuki [Department of Chemistry, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551 (Japan); Suzuki, Isao H, E-mail: joe@chem.titech.ac.j [Photon Factory, IMSS, KEK, Tsukuba, Ibaraki 305-0801 (Japan)

    2009-11-01

    Symmetry-resolved spectroscopy for investigating the doubly excited states of molecular hydrogen has been newly developed, where a metastable hydrogen atom dissociating in a direction parallel and perpendicular to the electric vector of the linearly polarized incident light is detected.

  6. Fabrication of mechano-optical sensors for hydrogen gas

    NARCIS (Netherlands)

    Pham Van So, P.V.S.; Kauppinen, L.J.; Dijkstra, Mindert; van Wolferen, Hendricus A.G.M.; de Ridder, R.M.; Hoekstra, Hugo

    2009-01-01

    We present results related to the fabrication of a novel and highly sensitive mechano-optical sensor for hydrogen gas, based on microcantilevers, supplied with a selective gas absorbing layer (Pd), suspended above a Si3N4 grated waveguide (GWG). Integrated microcantilever-GWG devices have been

  7. The role of atomic hydrogen in regulating the scatter of the mass-metallicity relation

    Science.gov (United States)

    Brown, Toby; Cortese, Luca; Catinella, Barbara; Kilborn, Virginia

    2018-01-01

    In this paper, we stack neutral atomic hydrogen (H I) spectra for 9720 star-forming galaxies along the mass-metallicity relation. The sample is selected according to stellar mass (109 ≤ M⋆/M⊙ ≤ 1011) and redshift (0.02 ≤ z ≤ 0.05) from the overlap of the Sloan Digital Sky Survey and Arecibo Legacy Fast ALFA survey. We confirm and quantify the strong anticorrelation between H I mass and gas-phase metallicity at fixed stellar mass. Furthermore, we show for the first time that the relationship between gas content and metallicity is consistent between different metallicity estimators, contrary to the weaker trends found with star formation which are known to depend on the observational techniques used to derive oxygen abundances and star formation rates. When interpreted in the context of theoretical work, this result supports a scenario where galaxies exist in an evolving equilibrium between gas, metallicity and star formation. The fact that deviations from this equilibrium are most strongly correlated with gas mass suggests that the scatter in the mass-metallicity relation is primarily driven by fluctuations in gas accretion.

  8. Quantum Diffusion-Controlled Chemistry: Reactions of Atomic Hydrogen with Nitric Oxide in Solid Parahydrogen.

    Science.gov (United States)

    Ruzi, Mahmut; Anderson, David T

    2015-12-17

    Our group has been working to develop parahydrogen (pH2) matrix isolation spectroscopy as a method to study low-temperature condensed-phase reactions of atomic hydrogen with various reaction partners. Guided by the well-defined studies of cold atom chemistry in rare-gas solids, the special properties of quantum hosts such as solid pH2 afford new opportunities to study the analogous chemical reactions under quantum diffusion conditions in hopes of discovering new types of chemical reaction mechanisms. In this study, we present Fourier transform infrared spectroscopic studies of the 193 nm photoinduced chemistry of nitric oxide (NO) isolated in solid pH2 over the 1.8 to 4.3 K temperature range. Upon short-term in situ irradiation the NO readily undergoes photolysis to yield HNO, NOH, NH, NH3, H2O, and H atoms. We map the postphotolysis reactions of mobile H atoms with NO and document first-order growth in HNO and NOH reaction products for up to 5 h after photolysis. We perform three experiments at 4.3 K and one at 1.8 K to permit the temperature dependence of the reaction kinetics to be quantified. We observe Arrhenius-type behavior with a pre-exponential factor of A = 0.036(2) min(-1) and Ea = 2.39(1) cm(-1). This is in sharp contrast to previous H atom reactions we have studied in solid pH2 that display definitively non-Arrhenius behavior. The contrasting temperature dependence measured for the H + NO reaction is likely related to the details of H atom quantum diffusion in solid pH2 and deserves further study.

  9. Molecular dynamics simulation of effect of hydrogen atoms on crack propagation behavior of α-Fe

    Energy Technology Data Exchange (ETDEWEB)

    Song, H.Y., E-mail: gsfshy@sohu.com; Zhang, L.; Xiao, M.X.

    2016-12-16

    The effect of the hydrogen concentration and hydrogen distribution on the mechanical properties of α-Fe with a pre-existing unilateral crack under tensile loading is investigated by molecular dynamics simulation. The results reveal that the models present good ductility when the front region of crack tip has high local hydrogen concentration. The peak stress of α-Fe decreases with increasing hydrogen concentration. The studies also indicate that for the samples with hydrogen atoms, the crack propagation behavior is independent of the model size and boundaries. In addition, the crack propagation behavior is significantly influenced by the distribution of hydrogen atoms. - Highlights: • The distribution of hydrogen plays a critical role in the crack propagation. • The peak stress decrease with the hydrogen concentration increasing. • The crack deformation behavior is disclosed and analyzed.

  10. Collisions at thermal energy between metastable hydrogen atoms and hydrogen molecules: Total and differential cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Vassilev, G.; Perales, F.; Miniatura, C.; Robert, J.; Reinhardt, J.; Vecchiocattivi, F.; Baudon, J. (Paris-13 Univ., 93 - Villetaneuse (France). Lab. de Physique des Lasers)

    1990-10-01

    A metastable hydrogen (deuterium) atom source in which groundstate atoms produced by a RF discharge dissociator are bombarded by electrons, provides a relatively large amount of slow metastable atoms (velocity 3-5 km/s). Total integral cross sections for H{sup *}(D{sup *})(2s)+H{sub 2}(X{sup 1}{Sigma}{sub g}{sup +}, {nu}=0) collisions have been measured in a wide range of relative velocity (2,5-30 km/s), by using the attenuation method. A significant improvement of accuracy is obtained, with respect to previous measurements, at low relative velocities. Total cross sections for H{sup *} and D{sup *}, as functions of the relative velocity, are different, especially in the low velocity range. H{sup *}+H{sub 2} total differential cross sections have also been measured, with an angular spread of 3.6deg, for two different collision energy distributions, centered respectively at 100 meV and 390 meV. A first attempt of theoretical analysis of the cross sections, by means of an optical potential, is presented. (orig.).

  11. Adsorption of hydrogen gas and redox processes in clays.

    Science.gov (United States)

    Didier, Mathilde; Leone, Laura; Greneche, Jean-Marc; Giffaut, Eric; Charlet, Laurent

    2012-03-20

    In order to assess the adsorption properties of hydrogen gas and reactivity of adsorbed hydrogen, we measured H(2)(g) adsorption on Na synthetic montmorillonite-type clays and Callovo-Oxfordian (COx) clayrock using gas chromatography. Synthetic montmorillonites with increasing structural Fe(III) substitution (0 wt %, 3.2 wt %, and 6.4 wt % Fe) were used. Fe in the synthetic montmorillonites is principally present as structural Fe(III) ions. We studied the concomitant reduction of structural Fe(III) in the clays using (57)Fe Mössbauer spectrometry. The COx, which mainly contains smectite/illite and calcite minerals, is also studied together with the pure clay fraction of this clayrock. Experiments were performed with dry clay samples which were reacted with hydrogen gas at 90 and 120 °C for 30 to 45 days at a hydrogen partial pressure close to 0.45 bar. Results indicate that up to 0.11 wt % of hydrogen is adsorbed on the clays at 90 °C under 0.45 bar of relative pressure. (57)Fe Mössbauer spectrometry shows that up to 6% of the total structural Fe(III) initially present in these synthetic clays is reduced upon adsorption of hydrogen gas. No reduction is observed with the COx sample in the present experimental conditions.

  12. Production of hydrogen by thermocatalytic cracking of natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Muradov, N.Z. [Univ. of Central Florida, Cape Canaveral, FL (United States)

    1995-09-01

    It is universally accepted that in the next few decades hydrogen production will continue to rely on fossil fuels (primarily, natural gas). On the other hand, the conventional methods of hydrogen production from natural gas (for example, steam reforming) are complex multi-step processes. These processes also result in the emission of large quantities of CO{sub 2} into the atmosphere that produce adverse ecological effects. One alternative is the one-step thermocatalytic cracking (TCC) (or decomposition) of natural gas into hydrogen and carbon. Preliminary analysis indicates that the cost of hydrogen produced by thermal decomposition of natural gas is somewhat lower than the conventional processes after by-product carbon credit is taken. In the short term, this process can be used for on-site production of hydrogen-methane mixtures in gas-filling stations and for CO{sub x}-free production of hydrogen for fuel cell driven prime movers. The experimental data on the thermocatalytic cracking of methane over various catalysts and supports in a wide range of temperatures (500-900{degrees}C) are presented in this paper. Two types of reactors were designed and built at FSEC: continuous flow and pulse fix bed catalytic reactors. The temperature dependence of the hydrogen production yield using oxide type catalysts was studied. Alumina-supported Ni- and Fe-catalysts demonstrated relatively high efficiency in the methane cracking reaction at moderate temperatures (600-800{degrees}C). Kinetic curves of hydrogen production over metal and metal oxide catalysts at different temperatures are presented in the paper. Fe-catalyst demonstrated good stability (for several hours), whereas alumina-supported Pt-catalyst rapidly lost its catalytic activity.

  13. Relation between the parameters of dust and of molecular and atomic gas in extragalactic star-forming regions

    Science.gov (United States)

    Smirnova, K. I.; Murga, M. S.; Wiebe, D. S.; Sobolev, A. M.

    2017-08-01

    The relationships between atomic and molecular hydrogen and dust of various sizes in extragalactic star-forming regions are considered, based on observational data from the Spitzer and Herschel infrared space telescopes, the Very Large Array (atomic hydrogen emission) and IRAM (CO emission). The source sample consists of approximately 300 star-forming regions in 11 nearby galaxies. Aperture photometry has been applied to measure the fluxes in eight infrared bands (3.6, 4.5, 5.8, 8, 24, 70, 100, and 160 μm), the atomic hydrogen 21 cm line, and CO (2-1) line. The parameters of the dust in the starforming regions were determined via synthetic-spectra fitting, such as the total dust mass, the fraction of polycyclic aromatic hydrocarbons (PAHs), etc. Comparison of the observed fluxes with the measured parameters shows that the relationships between atomic hydrogen, molecular hydrogen, and dust are different in low- and high-metallicity regions. Low-metallicity regions contain more atomic gas, but less molecular gas and dust, including PAHs. The mass of dust constitutes about 1% of the mass of molecular gas in all regions considered. Fluxes produced by atomic and molecular gas do not correlate with the parameters of the stellar radiation, whereas the dust fluxes grow with increasing mean intensity of stellar radiation and the fraction of enhanced stellar radiation. The ratio of the fluxes at 8 and 24 μm, which characterizes the PAH content, decreases with increasing intensity of the stellar radiation, possibly indicating evolutionary variations of the PAH content. The results confirm that the contribution of the 24 μm emission to the total IR luminosity of extragalactic star-forming regions does not depend on the metallicity.

  14. Improved Hydrogen Gas Getters for TRU Waste -- Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Mark Stone; Michael Benson; Christopher Orme; Thomas Luther; Eric Peterson

    2005-09-01

    Alpha radiolysis of hydrogenous waste and packaging materials generates hydrogen gas in radioactive storage containers. For that reason, the Nuclear Regulatory Commission limits the flammable gas (hydrogen) concentration in the Transuranic Package Transporter-II (TRUPACT-II) containers to 5 vol% of hydrogen in air, which is the lower explosion limit. Consequently, a method is needed to prevent the build up of hydrogen to 5 vol% during the storage and transport of the TRUPACT-II containers (up to 60 days). One promising option is the use of hydrogen getters. These materials scavenge hydrogen from the gas phase and irreversibly bind it in the solid phase. One proven getter is a material called 1,4-bis (phenylethynyl) benzene, or DEB, characterized by the presence of carbon-carbon triple bonds. Carbon may, in the presence of suitable precious metal catalysts such as palladium, irreversibly react with and bind hydrogen. In the presence of oxygen, the precious metal may also eliminate hydrogen by catalyzing the formation of water. This reaction is called catalytic recombination. DEB has the needed binding rate and capacity for hydrogen that potentially could be generated in the TRUPACT II. Phases 1 and 2 of this project showed that uncoated DEB performed satisfactorily in lab scale tests. Based upon these results, Phase 3, the final project phase, included larger scale testing. Test vessels were scaled to replicate the ratio between void space in the inner containment vessel of a TRUPACT-II container and a payload of seven 55-gallon drums. The tests were run with an atmosphere of air for 63.9 days at ambient temperature (15-27°C) and a scaled hydrogen generation rate of 2.60E-07 moles per second (0.35 cc/min). A second type of getter known as VEI, a proprietary polymer hydrogen getter characterized by carbon-carbon double bonds, was also tested in Phase 3. Hydrogen was successfully “gettered” by both getter systems. Hydrogen concentrations remained below 5 vol% (in

  15. NO2 gas sensor based on hydrogenated graphene

    Science.gov (United States)

    Park, Sungjin; Park, Minji; Kim, Sunghyun; Yi, Sum-Gyun; Kim, Myeongjin; Son, Jangyup; Cha, Jongin; Hong, Jongill; Yoo, Kyung-Hwa

    2017-11-01

    We investigated the relationship between defects in graphene and NO2 gas sensitivity of graphene-based gas sensors. Defects were introduced by hydrogen plasma or ultraviolet (UV)/ozone treatment. As the defect concentration increased, the sensitivity was enhanced, and sub-ppb level detection limit was achieved. UV irradiation was used for recovery at room temperature. However, defects generated by ozone treatment, like graphene oxide, were reduced back to graphene by UV irradiation, so the ozone-treated graphene sensor was not stable over time. In contrast, the response of the hydrogenated graphene sensor was very repeatable because defects generated by hydrogenation was stable enough not to be dehydrogenated by UV irradiation. These results demonstrate that the hydrogenated graphene sensor is a highly sensitive and stable NO2 sensor at room temperature.

  16. Combustion gas properties. Part 3: Hydrogen gas fuel and dry air

    Science.gov (United States)

    Wear, J. D.; Jones, R. E.; Mcbride, B. J.; Beyerle, R. A.

    1985-01-01

    A series of computations has been made to produce the equilibrium temperature and gas composition for hydrogen gas fuel and dry air. The computed tables and figures provide combustion gas property data for pressures from 0.5 to 50 atmospheres and equivalence ratios from 0 to 2.0. Only sample tables and figures are provided in this report.

  17. A shear reversal nozzle for efficient gas atomization

    Energy Technology Data Exchange (ETDEWEB)

    Brown, S.W.

    1992-12-01

    The primary purpose of this report is to establish definitive rationale and technical drivers for atomizing nozzles that employ the shear reversal principle. In a shear reversing nozzle, the liquid to be atomized is introduced into a supersonic gas flow and is allowed to accelerate to a velocity near that of the gas before it exits the nozzle. The pressure conditions at the exit of the nozzle are managed in such a manner to produce a strong normal shock wave in the gas flow field. The shock wave causes a large reduction in the gas velocity at the exit of the nozzle. Because the liquid is traveling near the initial gas velocity as it exits the nozzle, it now encounters a relatively slow moving gas flow field, which causes further reductions in the particle size. An elementary atomizing model is presented comprising two distinct processes: (1) particle divisions and (2) particle shearing. From the model, the primary process variables were identified and strategies were presented to maximize the production of fine diameter particles. In addition, an elementary finite difference model was presented to aid in the determination of the overall length of the shear reversing nozzle. Finally, a procedure was given to establish proper sizing of the components involved.

  18. Hydrogen atom addition to the surface of graphene nanoflakes: A density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Tachikawa, Hiroto, E-mail: hiroto@eng.hokudai.ac.jp

    2017-02-28

    Highlights: • The reaction pathway of the hydrogen addition to graphene surface was determined by the DFT method. • Binding energies of atomic hydrogen to graphene surface were determined. • Absorption spectrum of hydrogenated graphene was theoretically predicted. • Hyperfine coupling constant of hydrogenated graphene was theoretically predicted. - Abstract: Polycyclic aromatic hydrocarbons (PAHs) provide a 2-dimensional (2D) reaction surface in 3-dimensional (3D) interstellar space and have been utilized as a model of graphene surfaces. In the present study, the reaction of PAHs with atomic hydrogen was investigated by means of density functional theory (DFT) to systematically elucidate the binding nature of atomic hydrogen to graphene nanoflakes. PAHs with n = 4–37 were chosen, where n indicates the number of benzene rings. Activation energies of hydrogen addition to the graphene surface were calculated to be 5.2–7.0 kcal/mol at the CAM-B3LYP/6-311G(d,p) level, which is almost constant for all PAHs. The binding energies of hydrogen atom were slightly dependent on the size (n): 14.8–28.5 kcal/mol. The absorption spectra showed that a long tail is generated at the low-energy region after hydrogen addition to the graphene surface. The electronic states of hydrogenated graphenes were discussed on the basis of theoretical results.

  19. Hydrogen Gas Production in a Stand-Alone Wind Farm

    Directory of Open Access Journals (Sweden)

    M. Naziry Kordkandy

    2017-04-01

    Full Text Available This paper is analyzing the operation of a stand-alone wind farm with variable speed turbines, permanent magnet synchronous generators (PMSG and a system for converting wind energy during wind speed variations. On this paper, the design and modeling of a wind system which uses PMSG’s to provide the required power of a hydrogen gas electrolyzer system, is discussed. This wind farm consists of three wind turbines, boost DC-DC converters, diode full bridge rectifiers, permanent magnet synchronous generators, MPPT control and a hydrogen gas electrolyzer system. The MPPT controller based on fuzzy logic is designed to adjust the duty ratio of the boost DC-DC converters to absorb maximum power. The proposed fuzzy logic controller assimilates, with (PSF MPPT algorithm which generally used to absorb maximum power from paralleled wind turbines and stores it in form of hydrogen gas. The system is modeled and its behavior is studied using the MATLAB software.

  20. An atomic hydrogen beam to test ASACUSA's apparatus for antihydrogen spectroscopy

    CERN Document Server

    Diermaier, Martin; Kolbinger, Bernadette; Malbrunot, Chloé; Massiczek, Oswald; Sauerzopf, Clemens; Simon, Martin C.; Wolf, Michael; Zmeskal, Johann; Widmann, Eberhard

    2015-01-01

    The ASACUSA collaboration aims to measure the ground state hyperfine splitting (GS-HFS) of antihydrogen, the antimatter pendant to atomic hydrogen. Comparisons of the corresponding transitions in those two systems will provide sensitive tests of the CPT symmetry, the combination of the three discrete symmetries charge conjugation, parity, and time reversal. For offline tests of the GS-HFS spectroscopy apparatus we constructed a source of cold polarised atomic hydrogen. In these proceedings we report the successful observation of the hyperfine structure transitions of atomic hydrogen with our apparatus in the earth's magnetic field.

  1. Blending Hydrogen into Natural Gas Pipeline Networks. A Review of Key Issues

    Energy Technology Data Exchange (ETDEWEB)

    Melaina, M. W. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Antonia, O. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Penev, M. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2013-03-01

    This study assesses the potential to deliver hydrogen through the existing natural gas pipeline network as a hydrogen and natural gas mixture to defray the cost of building dedicated hydrogen pipelines. Blending hydrogen into the existing natural gas pipeline network has also been proposed as a means of increasing the output of renewable energy systems such as large wind farms.

  2. Gas chromatography flow rates for determining deuterium/hydrogen ratios of natural gas by gas chromatography/high-temperature conversion/isotope ratio mass spectrometry.

    Science.gov (United States)

    Jia, Wanglu; Peng, Ping'an; Liu, Jinzhong

    2008-08-01

    The effects of the gas chromatography flow rate on the determination of the deuterium/hydrogen (D/H) ratios of natural gas utilising gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/TC/IRMS) have been evaluated. In general, the measured deltaD values of methane, ethane and propane decrease with increase in column flow rate. When the column flow rate is 1 mL/min or higher, which is commonly used for the determination of D/H ratios of natural gas, the organic H in gas compounds may not be completely converted into hydrogen gas. Based on the results of experiments conducted on a GC column with an i.d. of 0.32 mm, a GC flow rate of 0.6 mL/min is proposed for determining the D/H ratios of natural gas by GC/TC/IRMS. Although this value may be dependent on the instrument conditions used in this work, we believe that correct deltaD values of organic compounds with a few carbon atoms are obtained only when relatively low GC flow rates are used for D/H analysis by GC/TC/IRMS. Moreover, as the presence of trace water could significantly affect the determination of D/H ratios, a newly designed inlet liner was used to remove trace water contained in some gas samples. Copyright (c) 2008 John Wiley & Sons, Ltd.

  3. Tunable Electrical Properties of Vanadium Oxide by Hydrogen-Plasma-Treated Atomic Layer Deposition

    Directory of Open Access Journals (Sweden)

    Helen Hejin Park

    2017-04-01

    Full Text Available In this study, a plasma-modified process was developed to control the electrical properties of atomic layer deposition (ALD-grown vanadium dioxide (VO2, which is potentially useful for applications such as resistive switching devices, bolometers, and plasmonic metamaterials. By inserting a plasma pulse with varying H2 gas flow into each ALD cycle, the insulator-to-metal transition (IMT temperature of postdeposition-annealed crystalline VO2 films was adjusted from 63 to 78 °C. Film analyses indicate that the tunability may arise from changes in grain boundaries, morphology, and compositional variation despite hydrogen not remaining in the annealed VO2 films. This growth method, which enables a systematic variation of the electronic behavior of VO2, provides capabilities beyond those of the conventional thermal ALD and plasma-enhanced ALD.

  4. Chemical reactivity of the compressed noble gas atoms and their ...

    Indian Academy of Sciences (India)

    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 ...

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

    Science.gov (United States)

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

    2015-08-27

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

  6. Determination of the Kinematics of the Qweak Experiment and Investigation of an Atomic Hydrogen Moller Polarimeter

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Valerie M. [College of William and Mary, Williamsburg, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2018-01-01

    The Qweak experiment has tested the Standard Model through making a precise measurement of the weak charge of the proton (QpW). This was done through measuring the parity-violating asymmetry for polarized electrons scattering off of unpolarized protons. The parity-violating asymmetry measured is directly proportional to the four-momentum transfer (Q^2) from the electron to the proton. The extraction of QpW from the measured asymmetry requires a precise Q^2 determination. The Qweak experiment had a Q^2 = 24.8 ± 0.1 m(GeV^2) which achieved the goal of an uncertainty of <= 0.5%. From the measured asymmetry and Q^2, QpW was determined to be 0.0719 ± 0.0045, which is in good agreement with the Standard Model prediction. This puts a 7.5 TeV lower limit on possible "new physics". This dissertation describes the analysis of Q^2 for the Qweak experiment. Future parity-violating electron scattering experiments similar to the Qweak experiment will measure asymmetries to high precision in order to test the Standard Model. These measurements will require the beam polarization to be measured to sub-0.5% precision. Presently the electron beam polarization is measured through Moller scattering off of a ferromagnetic foil or through using Compton scattering, both of which can have issues reaching this precision. A novel Atomic Hydrogen Moller Polarimeter has been proposed as a non-invasive way to measure the polarization of an electron beam via Moller scattering off of polarized monatomic hydrogen gas. This dissertation describes the development and initial analysis of a Monte Carlo simulation of an Atomic Hydrogen Moller Polarimeter.

  7. Production of bioplastics and hydrogen gas by photosynthetic microorganisms

    Science.gov (United States)

    Yasuo, Asada; Masato, Miyake; Jun, Miyake

    1998-03-01

    Our efforts have been aimed at the technological basis of photosynthetic-microbial production of materials and an energy carrier. We report here accumulation of poly-(3-hydroxybutyrate) (PHB), a raw material of biodegradable plastics and for production of hydrogen gas, and a renewable energy carrier by photosynthetic microorganisms (tentatively defined as cyanobacteria plus photosynthetic bateria, in this report). A thermophilic cyanobacterium, Synechococcus sp. MA19 that accumulates PHB at more than 20% of cell dry wt under nitrogen-starved conditions was isolated and microbiologically identified. The mechanism of PHB accumulation was studied. A mesophilic Synechococcus PCC7942 was transformed with the genes encoding PHB-synthesizing enzymes from Alcaligenes eutrophus. The transformant accumulated PHB under nitrogen-starved conditions. The optimal conditions for PHB accumulation by a photosynthetic bacterium grown on acetate were studied. Hydrogen production by photosynthetic microorganisms was studied. Cyanobacteria can produce hydrogen gas by nitrogenase or hydrogenase. Hydrogen production mediated by native hydrogenase in cyanobacteria was revealed to be in the dark anaerobic degradation of intracellular glycogen. A new system for light-dependent hydrogen production was targeted. In vitro and in vivo coupling of cyanobacterial ferredoxin with a heterologous hydrogenase was shown to produce hydrogen under light conditions. A trial for genetic trasformation of Synechococcus PCC7942 with the hydrogenase gene from Clostridium pasteurianum is going on. The strong hydrogen producers among photosynthetic bacteria were isolated and characterized. Co-culture of Rhodobacter and Clostriumdium was applied to produce hydrogen from glucose. Conversely in the case of cyanobacteria, genetic regulation of photosynthetic proteins was intended to improve conversion efficiency in hydrogen production by the photosynthetic bacterium, Rhodobacter sphaeroides RV. A mutant acquired by

  8. Hydrogen Peroxide Gas Generator Cycle with a Reciprocating Pump

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J C

    2002-06-11

    A four-chamber piston pump is powered by decomposed 85% hydrogen peroxide. The performance envelope of the evolving 400 gram pump has been expanded to 172 cc/s water flow at discharge pressures near 5 MPa. A gas generator cycle system using the pump has been tested under similar conditions of pressure and flow. The powerhead gas is derived from a small fraction of the pumped hydrogen peroxide, and the system starts from tank pressures as low as 0.2 MPa. The effects of steam condensation on performance have been evaluated.

  9. Low cost hydrogen/novel membrane technology for hydrogen separation from synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    1986-02-01

    To make the coal-to-hydrogen route economically attractive, improvements are being sought in each step of the process: coal gasification, water-carbon monoxide shift reaction, and hydrogen separation. This report addresses the use of membranes in the hydrogen separation step. The separation of hydrogen from synthesis gas is a major cost element in the manufacture of hydrogen from coal. Separation by membranes is an attractive, new, and still largely unexplored approach to the problem. Membrane processes are inherently simple and efficient and often have lower capital and operating costs than conventional processes. In this report current ad future trends in hydrogen production and use are first summarized. Methods of producing hydrogen from coal are then discussed, with particular emphasis on the Texaco entrained flow gasifier and on current methods of separating hydrogen from this gas stream. The potential for membrane separations in the process is then examined. In particular, the use of membranes for H{sub 2}/CO{sub 2}, H{sub 2}/CO, and H{sub 2}/N{sub 2} separations is discussed. 43 refs., 14 figs., 6 tabs.

  10. Blending Hydrogen into Natural Gas Pipeline Networks: A Review of Key Issues

    Energy Technology Data Exchange (ETDEWEB)

    Melaina, M. W.; Antonia, O.; Penev, M.

    2013-03-01

    The United States has 11 distinct natural gas pipeline corridors: five originate in the Southwest, four deliver natural gas from Canada, and two extend from the Rocky Mountain region. This study assesses the potential to deliver hydrogen through the existing natural gas pipeline network as a hydrogen and natural gas mixture to defray the cost of building dedicated hydrogen pipelines.

  11. Hydrogen-air energy storage gas-turbine system

    Science.gov (United States)

    Schastlivtsev, A. I.; Nazarova, O. V.

    2016-02-01

    A hydrogen-air energy storage gas-turbine unit is considered that can be used in both nuclear and centralized power industries. However, it is the most promising when used for power-generating plants based on renewable energy sources (RES). The basic feature of the energy storage system in question is combination of storing the energy in compressed air and hydrogen and oxygen produced by the water electrolysis. Such a process makes the energy storage more flexible, in particular, when applied to RES-based power-generating plants whose generation of power may considerably vary during the course of a day, and also reduces the specific cost of the system by decreasing the required volume of the reservoir. This will allow construction of such systems in any areas independent of the local topography in contrast to the compressed-air energy storage gas-turbine plants, which require large-sized underground reservoirs. It should be noted that, during the energy recovery, the air that arrives from the reservoir is heated by combustion of hydrogen in oxygen, which results in the gas-turbine exhaust gases practically free of substances hazardous to the health and the environment. The results of analysis of a hydrogen-air energy storage gas-turbine system are presented. Its layout and the principle of its operation are described and the basic parameters are computed. The units of the system are analyzed and their costs are assessed; the recovery factor is estimated at more than 60%. According to the obtained results, almost all main components of the hydrogen-air energy storage gas-turbine system are well known at present; therefore, no considerable R&D costs are required. A new component of the system is the H2-O2 combustion chamber; a difficulty in manufacturing it is the necessity of ensuring the combustion of hydrogen in oxygen as complete as possible and preventing formation of nitric oxides.

  12. Field test of hydrogen in the natural gas grid

    Energy Technology Data Exchange (ETDEWEB)

    Iskov, H.

    2010-08-15

    In order to prepare for a future use of hydrogen as a fuel gas it became evident that very little information existed regarding the compatibility between long-term exposure and transportation of hydrogen in natural gas pipelines. A program was therefore set to study the transportation in a small-scale pilot grid at the research centre in Hoersholm, Denmark. The test program included steel pipes from the Danish gas transmission grid and polymer pipes from the Danish and Swedish gas distribution grid. The test of polymer pipes was devised so that samples of all test pipes were cut out of the grid each year and analysis performed on these pipe samples; in this way any form of influence on the integrity of the polyethylene pipe would be detected. The analytical program for polymer was devised in order to detect any influence on the additivation of the polyethylene as this has an influence on oxidative resistance, as well as checking already encountered possible degradation caused by extrusion of the material. Further tools as rheology and melt flow rate were used for detecting any structural changes on the material. On the mechanical property side the tensile strength and modulus were followed as well as the most important property for the pipe line, namely slow crack growth. The results of the polymer pipe tests show no degradations of any kind related to the continuous hydrogen exposure for more than 4 years. This is a strong indication of the compatibility to hydrogen of the tested polymer materials PE 80 and PE 100. The object of the steel pipe test was to see the effect on fatigue life of existing natural gas transmission lines with hydrogen replacing the natural gas. Full-scale dynamic tests were performed using randomly selected cut-out API 5L X70 pipe sections with a diameter of 20 inches and a wall thickness of 7 millimetres from the Danish natural gas transmission system. The pipe sections contained field girth weld made during the installation of the pipe

  13. Influences of atomic hydrogen on porous low-k dielectric for 45-nm node

    Energy Technology Data Exchange (ETDEWEB)

    Tomioka, K. [Semiconductor Leading Edge Technologies, Inc., 16-1 Onogawa, Tsukuba, Ibaraki, 305-8569 (Japan)]. E-mail: tomioka.kazuhiro@selete.co.jp; Soda, E. [Semiconductor Leading Edge Technologies, Inc., 16-1 Onogawa, Tsukuba, Ibaraki, 305-8569 (Japan); Kobayashi, N. [Semiconductor Leading Edge Technologies, Inc., 16-1 Onogawa, Tsukuba, Ibaraki, 305-8569 (Japan); Takata, M. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531 (Japan); Uda, S. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531 (Japan); Ogushi, K. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531 (Japan); Yuba, Y. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531 (Japan); Akasaka, Y. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531 (Japan)

    2007-04-23

    Atomic hydrogen generated by a heated tungsten catalyzer has been investigated in terms of the damage-less ash and restoration of damaged low-k dielectric. No difference of damaged thickness of low-k dielectric between before and after the ash by HF dip using patterned porous methyl silsesquioxane (MSQ) film was found. Moreover atomic hydrogen exposure slightly reduced capacitance of the micro-structured capacitor with the Cu wire and the CVD porous low-k dielectric.

  14. First detection of hydrogen in the β Pictoris gas disk

    Science.gov (United States)

    Wilson, P. A.; Lecavelier des Etangs, A.; Vidal-Madjar, A.; Bourrier, V.; Hébrard, G.; Kiefer, F.; Beust, H.; Ferlet, R.; Lagrange, A.-M.

    2017-03-01

    The young and nearby star β Pictoris (β Pic) is surrounded by a debris disk composed of dust and gas known to host a myriad evaporating exocomets, planetesimals and at least one planet. At an edge-on inclination, as seen from Earth, this system is ideal for debris disk studies providing an excellent opportunity to use absorption spectroscopy to study the planet forming environment. Using the Cosmic Origins Spectrograph (COS) instrument on the Hubble Space Telescope (HST) we observe the most abundant element in the disk, hydrogen, through the H I Lyman α (Ly-α) line. We present a new technique to decrease the contamination of the Ly-α line by geocoronal airglow in COS spectra. This Airglow Virtual Motion (AVM) technique allows us to shift the Ly-α line of the astrophysical target away from the contaminating airglow emission revealing more of the astrophysical line profile. This new AVM technique, together with subtraction of an airglow emission map, allows us to analyse the shape of the β Pic Ly-α emission line profile and from it, calculate the column density of neutral hydrogen surrounding β Pic. The column density of hydrogen in the β Pic stable gas disk at the stellar radial velocity is measured to be log (NH/ 1 cm2) ≪ 18.5. The Ly-α emission line profile is found to be asymmetric and we propose that this is caused by H I falling in towards the star with a bulk radial velocity of 41 ± 6 km s-1 relative to β Pic and a column density of log (NH/ 1 cm2) = 18.6 ± 0.1. The high column density of hydrogen relative to the hydrogen content of CI chondrite meteorites indicates that the bulk of the hydrogen gas does not come from the dust in the disk. This column density reveals a hydrogen abundance much lower than solar, which excludes the possibility that the detected hydrogen could be a remnant of the protoplanetary disk or gas expelled by the star. We hypothesise that the hydrogen gas observed falling towards the star arises from the dissociation of

  15. Dynamic gas bearing turbine technology in hydrogen plants

    Science.gov (United States)

    Ohlig, Klaus; Bischoff, Stefan

    2012-06-01

    Dynamic Gas Bearing Turbines - although applied for helium refrigerators and liquefiers for decades - experienced limitations for hydrogen applications due to restrictions in axial bearing capacity. With a new design concept for gas bearing turbines developed in 2004, axial bearing capacity was significantly improved enabling the transfer of this technology to hydrogen liquefiers. Prior to roll-out of the technology to industrial plants, the turbine bearing technology passed numerous tests in R&D test benches and subsequently proved industrial scale demonstration at Linde Gas' hydrogen liquefier in Leuna, Germany. Since its installation, this turbine has gathered more than 16,000 successful operating hours and has outperformed its oil bearing brother in terms of performance, maintainability as well as reliability. The present paper is based on Linde Kryotechnik AG's paper published in the proceedings of the CEC 2009 concerning the application of Dynamic Gas Bearing Turbines in hydrogen applications. In contrast to the former paper, this publication focuses on the steps towards final market launch and more specifically on the financial benefits of this turbine technology, both in terms of capital investment as well as operating expenses.

  16. Utilization of hydrogen gas production for electricity generation in ...

    African Journals Online (AJOL)

    Enterobacter aerogenes ADH-43 is a hydrogen gas (H2) producing mutant bacterium and a facultative anaerobic microbe. This double mutant was obtained by classical mutagenetically treated in order to enhance H2 production. In addition, this mutant has ability to degrade molasses from sugar factory as well as other ...

  17. Utilization of hydrogen gas production for electricity generation in ...

    African Journals Online (AJOL)

    Lecturer

    2012-05-03

    May 3, 2012 ... Enterobacter aerogenes ADH-43 is a hydrogen gas (H2) producing mutant bacterium and a facultative anaerobic microbe. This double mutant was obtained by classical mutagenetically treated in order to enhance H2 production. In addition, this mutant has ability to degrade molasses from sugar factory as.

  18. Transcendental-function representation of Stark-modified hydrogenic states and atomic dipole polarizability

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, A.; Talukdar, B. [Department of Physics, Visva-Bharati University, Santiniketan (India); Banerji, G. [Mathematics Department, BU, Burdwan (India); Roy, U. [Theoretical Physics Department, IACS, Calcutta (India)

    1998-01-30

    A differential equation approach to the perturbation theoretic correction for excited hydrogenic states is introduced. The radial equations for the problem are solved in terms of known transcendental functions and the method to determine the complete primitive is discussed. The constructed perturbative correction to the wavefunction is adapted to evaluate the dipole polarizability of hydrogenic atoms. (author)

  19. Understanding Hydrogen Atom Transfer: from Bond Strengths to Marcus Theory

    Science.gov (United States)

    MAYER, JAMES M.

    2010-01-01

    CONSPECTUS Hydrogen atom transfer (HAT) is one of the most fundamental chemical reactions: A–H + B → A + H–B. It is a key step in a wide range of chemical, environmental, and biological processes. Traditional HAT involves p-block radicals such as tBuO• abstracting H• from organic molecules. More recently, it has been recognized that many transition metal species undergo HAT. This has led to a broader perspective, with HAT viewed as one type of proton-coupled electron transfer (PCET). When transition metal complexes oxidize substrates by removing H• (≡ e– and H+), typically the electron transfers to the metal and the proton transfers to a ligand. Two examples are shown in the Figure: iron-imidazolinate and vanadium-oxo complexes. Although such reagents do not “look like” main group radicals, they have the same pattern of reactivity. For instance, their HAT rate constants parallel the A–H bond strengths within a series of similar reactions. Just like main group radicals, they abstract H• much faster from O–H bonds than from C–H bonds of the same strength. This shows that driving force is not the only determinant of reactivity. We have found that HAT reactivity is well described using a Marcus-theory approach. In the simplest model, the cross relation, kAH/B = (kAH/AkBH/BKeqf)½, predicts the rate constant for AH + B in terms of the self-exchange rate constants (kAH/A for AH + A) and the equilibrium constant. For a variety of transition metal oxidants, kAH/B is predicted within one or two orders of magnitude with only a few exceptions. For 36 organic reactions of oxyl radicals, kAH/B is predicted with an average deviation of a factor of 3.8, and within a factor of 5 for all but six of the reactions. These reactions involve both O–H or C–H bonds, occur either in water or organic solvents, and over a range of 1028 in Keq and 1013 in kAH/B. The treatment of organic reactions of O–H bonds includes the well-established kinetic solvent

  20. Thermodynamic behavior of hydrogen/natural gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Agahi, R.R.; Ershaghi, B.; Lin, M.C. [Atlas Copco Rotoflow, Gardena, CA (United States); Mansoori, A. [Univ. of Illinois, Chicago, IL (United States)

    1995-11-01

    The process gas of ethylene plants and methyl tertiary butyl ether plants is normally a hydrogen/methane mixture. The molecular weight of the gas in such processes ranges from 3.5 to 14. Thermodynamic behavior of hydrogen/methane mixture has been and is being researched extensively. The gas dynamic design of turboexpanders which are extensively utilized in such plants depends on the equations of state of the process gas. Optimum performance of the turboexpanders and associated equipment demands accurate thermodynamic properties for a wide range of process gas conditions. The existing equations of state, i.e. Benedict-Webb-Rubin (BWR), Soave-Redlich, Kwange and Peng-Robinson have some practical limitations. The equations of state developed by the University of Illinois also have only a limited range of applications. By using the various equations of state, especially in the vapor-liquid equilibrium region, this paper shows that predictions by the various models are not the same and that they also differ from actual field results. The field data collected for hydrogen/methane mixtures are in the range of 100 F to {minus}200 F containing some polar components i.e. H{sub 2}S and CO{sub 2}. In this paper, the authors compare performance of several equations of state with the field performance of many expander units.

  1. Magnetic resonance studies of atomic hydrogen at zero field and low temperature. Recombination and binding on liquid helium

    Energy Technology Data Exchange (ETDEWEB)

    Jochemsen, R.; Morrow, M.; Berlinsky, A.J.; Hardy, W.N. (British Columbia Univ., Vancouver (Canada). Dept. of Physics)

    1982-07-01

    Magnetic resonance studies at zero field are reported for atomic hydrogen gas confined in a closed glass bulb with helium-coated walls for T<1 K in a dilution refrigerator. Low-energy r.f. discharge pulses have been used to produce H atoms at temperatures as low as T=0.06 K. The atom density nsub(H) (10/sup 9/..H/sub 2/+wall. From the temperature dependence of the rate constant K we have determined the binding energy of H on liquid /sup 4/He and /sup 3/He, and also the cross section for recombination on the surface.

  2. Hydrogen gas sensor based on metal oxide nanoparticles decorated graphene transistor.

    Science.gov (United States)

    Zhang, Zhangyuan; Zou, Xuming; Xu, Lei; Liao, Lei; Liu, Wei; Ho, Johnny; Xiao, Xiangheng; Jiang, Changzhong; Li, Jinchai

    2015-06-14

    In this work, in order to enhance the performance of graphene gas sensors, graphene and metal oxide nanoparticles (NPs) are combined to be utilized for high selectivity and fast response gas detection. Whether at the relatively optimal temperature or even room temperature, our gas sensors based on graphene transistors, decorated with SnO2 NPs, exhibit fast response and short recovery times (∼1 seconds) at 50 °C when the hydrogen concentration is 100 ppm. Specifically, X-ray photoelectron spectroscopy and conductive atomic force microscopy are employed to explore the interface properties between graphene and SnO2 NPs. Through the complimentary characterization, a mechanism based on charge transfer and band alignment is elucidated to explain the physical originality of these graphene gas sensors: high carrier mobility of graphene and small energy barrier between graphene and SnO2 NPs have ensured a fast response and a high sensitivity and selectivity of the devices. Generally, these gas sensors will facilitate the rapid development of next-generation hydrogen gas detection.

  3. Production of hydrogen by thermocatalytic cracking of natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Muradov, N. [Florida Solar Energy Center, Cocoa, FL (United States)

    1996-10-01

    The conventional methods of hydrogen production from natural gas (for example, steam reforming and partial oxidation) are complex, multi-step processes that produce large quantities of CO{sub 2}. The main goal of this project is to develop a technologically simple process for hydrogen production from natural gas (NG) and other hydrocarbon fuels via single-step decomposition of hydrocarbons. This approach eliminates or significantly reduces CO{sub 2} emission. Carbon is a valuable by-product of this process, whereas conventional methods of hydrogen production from NG produce no useful by-products. This approach is based on the use of special catalysts that reduce the maximum temperature of the process from 1400-1500{degrees}C (thermal non-catalytic decomposition of methane) to 500-900{degrees}C. Transition metal based catalysts and various forms of carbon are among the candidate catalysts for the process. This approach can advantageously be used for the development of compact NG reformers for on-site production of hydrogen-methane blends at refueling stations and, also, for the production of hydrogen-rich gas for fuel cell applications. The author extended the search for active methane decomposition catalysts to various modifications of Ni-, Fe-, Mo- and Co-based catalysts. Variation in the operational parameters makes it possible to produce H{sub 2}-CH{sub 4} blends with a wide range of hydrogen concentrations that vary from 15 to 98% by volume. The author found that Ni-based catalysts are more effective at temperatures below 750{degrees}C, whereas Fe-based catalysts are effective at temperatures above 800{degrees}C for the production of hydrogen with purity of 95% v. or higher. The catalytic pyrolysis of liquid hydrocarbons (pentane, gasoline) over Fe-based catalyst was conducted. The author observed the production of a hydrogen-rich gas (hydrogen concentration up to 97% by volume) at a rate of approximately 1L/min.mL of hydrocarbon fuel.

  4. A spectroscopic study of hydrogen atom and molecule collision. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kielkopf, John F.

    2002-07-01

    The fundamental processes which occur in low-energy collisions of excited states of the hydrogen atom with other neutral atoms, protons, and electrons in dense plasmas were investigated in this project. Theoretical and experimental results for the Lyman and Balmer series are described here, including references to recent publications resulting from this project.

  5. Resonant Scattering of Muonic Hydrogen Atoms and Dynamics of the Muonic Molecular Complex

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, M. C., E-mail: Makoto.Fujiwara@cern.ch [University of British Columbia (Canada); Adamczak, A. [Institute Nuclear Physics (Poland); Bailey, J. M. [Chester Technology (United Kingdom); Beer, G. A. [University of Victoria (Canada); Beveridge, J. L. [TRIUMF (Canada); Faifman, M. P. [Kurchatov Institute (Russian Federation); Huber, T. M. [Gustavus Adolphus College (United States); Kammel, P. [University of Illinois at Urbana-Champaign (United States); Kim, S. K. [Jeonbuk National University (Korea, Republic of); Knowles, P. E. [Universite de Fribourg (Switzerland); Kunselman, A. R. [University of Wyoming (United States); Markushin, V. E. [Paul Scherrer Institute (Switzerland); Marshal, G. M. [TRIUMF (Canada); Mason, G. R. [University of Victoria (Canada); Mulhauser, F. [Universite de Fribourg (Switzerland); Olin, A. [TRIUMF (Canada); Petitjean, C. [Paul Scherrer Institute (Switzerland); Porcelli, T. A. [University of Northern British Columbia (Canada); Wozniak, J. [Institute Physics and Nuclear Techniques (Poland); Zmeskal, J. [Austrian Academy of Sciences (Austria)

    2001-12-15

    Resonant scattering of muonic hydrogen atoms via back decay of the molecular complex, a key process in the understanding of epithermal muonic molecular formation, is analyzed. The limitations of the effective rate approximation are discussed and the importance of the explicit treatment of the back decay is stressed. An expression of the energy distribution for the back-decayed atoms is given.

  6. Hydrogen atoms can be located accurately and precisely by x-ray crystallography.

    Science.gov (United States)

    Woińska, Magdalena; Grabowsky, Simon; Dominiak, Paulina M; Woźniak, Krzysztof; Jayatilaka, Dylan

    2016-05-01

    Precise and accurate structural information on hydrogen atoms is crucial to the study of energies of interactions important for crystal engineering, materials science, medicine, and pharmacy, and to the estimation of physical and chemical properties in solids. However, hydrogen atoms only scatter x-radiation weakly, so x-rays have not been used routinely to locate them accurately. Textbooks and teaching classes still emphasize that hydrogen atoms cannot be located with x-rays close to heavy elements; instead, neutron diffraction is needed. We show that, contrary to widespread expectation, hydrogen atoms can be located very accurately using x-ray diffraction, yielding bond lengths involving hydrogen atoms (A-H) that are in agreement with results from neutron diffraction mostly within a single standard deviation. The precision of the determination is also comparable between x-ray and neutron diffraction results. This has been achieved at resolutions as low as 0.8 Å using Hirshfeld atom refinement (HAR). We have applied HAR to 81 crystal structures of organic molecules and compared the A-H bond lengths with those from neutron measurements for A-H bonds sorted into bonds of the same class. We further show in a selection of inorganic compounds that hydrogen atoms can be located in bridging positions and close to heavy transition metals accurately and precisely. We anticipate that, in the future, conventional x-radiation sources at in-house diffractometers can be used routinely for locating hydrogen atoms in small molecules accurately instead of large-scale facilities such as spallation sources or nuclear reactors.

  7. Biomass & Natural Gas Based Hydrogen Fuel For Gas Turbine (Power Generation)

    Science.gov (United States)

    Significant progress has been made by major power generation equipment manufacturers in the development of market applications for hydrogen fuel use in gas turbines in recent years. Development of a new application using gas turbines for significant reduction of power plant CO2 e...

  8. Gas Phase Detection of the NH-P Hydrogen Bond and Importance of Secondary Interactions.

    Science.gov (United States)

    Møller, Kristian H; Hansen, Anne S; Kjaergaard, Henrik G

    2015-11-05

    We have observed the NH···P hydrogen bond in a gas phase complex. The bond is identified in the dimethylamine-trimethylphosphine complex by a red shift of the fundamental NH-stretching frequency observed using Fourier transform infrared spectroscopy (FT-IR). On the basis of the measured NH-stretching frequency red shifts, we find that P is a hydrogen bond acceptor atom similar in strength to S. Both are stronger acceptors than O and significantly weaker acceptors than N. The hydrogen bond angle, ∠NHP, is found to be very sensitive to the functional employed in density functional theory (DFT) optimizations of the complex and is a possible parameter to assess the quality of DFT functionals. Natural bonding orbital (NBO) energies and results from the topological methods atoms in molecules (AIM) and noncovalent interactions (NCI) indicate that the sensitivity is caused by the weakness of the hydrogen bond compared to secondary interactions. We find that B3LYP favors the hydrogen bond and M06-2X favors the secondary interactions leading to under- and overestimation, respectively, of the hydrogen bond angle relative to a DF-LCCSD(T)-F12a calculated angle. The remaining functionals tested, B3LYP-D3, B3LYP-D3BJ, CAM-B3LYP, and ωB97X-D, as well as MP2, show comparable contributions from the hydrogen bond and the secondary interactions and are close to DF-LCCSD(T)-F12a results.

  9. Degradation of fast electrons energy and atomic hydrogen generation in an emission plume from atomic power stations

    Science.gov (United States)

    Kolotkov, G. A.; Penin, S. T.; Chistyakova, L. K.

    2006-02-01

    The problem of remote detecting of a radioactivity in emissions from atomic power stations (APS) is devoted. The basic radionuclides contained in emissions of nuclear energy stations with various types of reactors have been analyzed. The total power spectrum of electrons is determined taking into account their multiplication. Physical and chemical reactions reducing to generation of atomic hydrogen are considered. For definition of the radiating volume in the emission from APS, the spatial distribution of atomic hydrogen concentration has been calculated with the use Pasquill- Gifford model. Power radiating by the emission plume from the APS with the BWR (Boiling Water Reactor) is estimated. It has been shown, that for estimation of radiation effect on the atmosphere, it is necessary to take into account many generations of electrons, because they have average energies exceeding considerably the ionization potentials for atoms and molecules of the atmospheric components. The area of the maximum concentration of atomic hydrogen in an emission plume can be determined by modelling the transport processes of admixture. The power radiated at frequency 1420 MHz by the volume 1 km from the APS emissions can amount to ~10 -13 W that allows one to detect the total level of activity confidently. The possible configuration of an emission plume has been calculated for various atmospheric stratification and underlying surfaces.

  10. Superfluidity in an Atomic Gas of Strongly Interacting Fermions

    Science.gov (United States)

    Ketterle, Wolfgang

    2011-03-01

    What is the benefit of realizing superfluidity in a gas a million times more dilute than air? Such systems consist of well-separated atoms which can be observed and manipulated with the control and precision of atomic physics, and which can be treated with first-principles calculations. By implementing scattering resonances, we have realized the strong-coupling limit of the Bardeen Schrieffer-Cooper (BCS) mechanism and observed a normalized transition temperature of 15% of the Fermi temperature, higher than in any superconductor. By tuning the strength of the interactions, the BEC-BCS crossover is realized. When the population of the two spin states is imbalanced, pairing is frustrated; and superfluidity is quenched at the Chandrasekhar-Clogston limit. These studies illustrate a new approach to condensed-matter physics where many-body Hamiltonians are realized in dilute atomic gases.

  11. Trapping of hydrogen atoms inside small beryllium clusters and their ions

    Science.gov (United States)

    Naumkin, F. Y.; Wales, D. J.

    2016-08-01

    Structure, stability and electronic properties are evaluated computationally for small Ben (n = 5-9) cluster cages accommodating atomic H inside and forming core-shell species. These parameters are predicted to vary significantly upon insertion of H, for ionic derivatives, and with the system size. In particular, the energy barrier for H-atom exit from the cage changes significantly for ions compared to the neutral counterparts. The corresponding effects predicted for cage assemblies suggest the possibility of efficient charge-control of hydrogen release. This, together with a high capacity for storing hydrogen in extended such assemblies might indicate a possible way towards feasible hydrogen-storage solutions.

  12. Adsorption Sites of Hydrogen Atom on Pure and Mg-Doped Multi-Walled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    A. A. Al-Ghamdi

    2012-01-01

    Full Text Available Hydrogen adsorption sites on pure multiwalled carbon nanotube (MWCNT and Mg-doped MWCNTs material system have been investigated using molecular dynamics (MD simulations as well as quantum chemical calculations. Through combining MWCNTs with Mg, the hydrogen adsorption sites energy on this Mg-MWCNTs system is found to be larger than that of the pure MWCNTs. Additionally, it was found that, through Mg-doping, new adsorption sites for hydrogen molecules are created in comparison with undoped nanotubes. It is also found that H atom is preferably adsorbed at every place near magnesium atom.

  13. Solid-phase microextraction may catalize hydrogenation when using hydrogen as carrier in gas chromatography.

    Science.gov (United States)

    Fiorini, D; Boarelli, M C

    2016-07-01

    When hydrogen is used as carrier gas, carbon-carbon double bonds may be hydrogenated in the hot gas chromatograph (GC) injector if introduced by solid-phase microextraction (SPME). SPME fibers coated with polydimethylsiloxane (PDMS)/carboxen/divinylbenzene (DVB), PDMS/carboxen, polyacrylate, PDMS/DVB and PDMS on fused silica, stableflex or metal alloy core have been tested with fatty acid methyl esters (FAMEs) from olive oil. Using coatings containing DVB, hydrogenation took place with high conversion rates (82.0-92.9%) independently of the core material. With all fibers having a metal core, hydrogenation was observed to a certain extent (27.4-85.3%). PDMS, PDMS/carboxen and polyacrylate coated fibers with a fused silica or stableflex core resulted in negligible hydrogenation (0.2-2.5%). The occurrence of hydrogenation was confirmed also with other substances containing carbon-carbon double bonds (n-alkenes, alkenoic acids, mono- and polyunsaturated fatty acid methyl and ethyl esters). Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Quantum yield and translational energy of hydrogen atoms

    Indian Academy of Sciences (India)

    TECS

    09) was determined by calibration method in which CH4 photolysis at 121⋅6 nm was used as a reference source of well-defined H atom concentrations. The line shapes of the measured H atom Doppler profiles indicate a Gaussian velocity ...

  15. Hydrogen storage and stability properties of Pd-Pt solid-solution nanoparticles revealed via atomic and electronic structure.

    Science.gov (United States)

    Kumara, Loku Singgappulige Rosantha; Sakata, Osami; Kobayashi, Hirokazu; Song, Chulho; Kohara, Shinji; Ina, Toshiaki; Yoshimoto, Toshiki; Yoshioka, Satoru; Matsumura, Syo; Kitagawa, Hiroshi

    2017-11-06

    Bimetallic Pd1-x Pt x solid-solution nanoparticles (NPs) display charging/discharging of hydrogen gas, which has relevance for fuel cell technologies; however, the constituent elements are immiscible in the bulk phase. We examined these material systems using high-energy synchrotron X-ray diffraction, X-ray absorption fine structure and hard X-ray photoelectron spectroscopy techniques. Recent studies have demonstrated the hydrogen storage properties and catalytic activities of Pd-Pt alloys; however, comprehensive details of their structural and electronic functionality at the atomic scale have yet to be reported. Three-dimensional atomic-scale structure results obtained from the pair distribution function (PDF) and reverse Monte Carlo (RMC) methods suggest the formation of a highly disordered structure with a high cavity-volume-fraction for low-Pt content NPs. The NP conduction band features, as extracted from X-ray absorption near-edge spectra at the Pd and Pt L III -edge, suggest that the Pd conduction band is filled by Pt valence electrons. This behaviour is consistent with observations of the hydrogen storage capacity of these NPs. The broadening of the valence band width and the down-shift of the d-band centre away from the Fermi level upon Pt substitution also provided evidence for enhanced stability of the hydride (ΔH) features of the Pd1-x Pt x solid-solution NPs with a Pt content of 8-21 atomic percent.

  16. Insights into the Hydrogen-Atom Transfer of the Blue Aroxyl.

    Science.gov (United States)

    Bächle, Josua; Marković, Marijana; Kelterer, Anne-Marie; Grampp, Günter

    2017-10-19

    An experimental and theoretical study on hydrogen-atom transfer dynamics in the hydrogen-bonded substituted phenol/phenoxyl complex of the blue aroxyl (2,4,6-tri-tert-butylphenoxyl) is presented. The experimental exchange dynamics is determined in different organic solvents from the temperature-dependent alternating line-width effect in the continuous-wave ESR spectrum. From bent Arrhenius plots, effective tunnelling contributions with parallel heavy-atom motion are concluded. To clarify the transfer mechanism, reaction paths for different conformers of the substituted phenol/phenoxyl complex are modelled theoretically. Various DFT and post-Hartree-Fock methods including multireference methods are applied. From the comparison of experimental and theoretical data it is concluded that the system favours concerted hydrogen-atom transfer along a parabolic reaction path caused by heavy-atom motion. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Hydrogen and Hydrogen/Natural Gas Station and Vehicle Operations - 2006 Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Francfort; Donald Karner; Roberta Brayer

    2006-09-01

    This report is a summary of the operations and testing of internal combustion engine vehicles that were fueled with 100% hydrogen and various blends of hydrogen and compressed natural gas (HCNG). It summarizes the operations of the Arizona Public Service Alternative Fuel Pilot Plant, which produces, compresses, and dispenses hydrogen fuel. Other testing activities, such as the destructive testing of a CNG storage cylinder that was used for HCNG storage, are also discussed. This report highlights some of the latest technology developments in the use of 100% hydrogen fuels in internal combustion engine vehicles. Reports are referenced and WWW locations noted as a guide for the reader that desires more detailed information. These activities are conducted by Arizona Public Service, Electric Transportation Applications, the Idaho National Laboratory, and the U.S. Department of Energy’s Advanced Vehicle Testing Activity.

  18. Hydrogen storage on high-surface-area carbon monoliths for Adsorb hydrogen Gas Vehicle

    Science.gov (United States)

    Soo, Yuchoong; Pfeifer, Peter

    2014-03-01

    Carbon briquetting can increase hydrogen volumetric storage capacity by reducing the useless void volume resulting in a better packing density. It is a robust and efficient space-filling form for an adsorbed hydrogen gas vehicle storage tank. To optimize hydrogen storage capacity, we studied three fabrication process parameters: carbon-to-binder ratio, compaction temperature, and pyrolysis atmosphere. We found that carbon-to-binder ratio and pyrolysis atmosphere have influences on gravimetric excess adsorption. Compaction temperature has large influences on gravimetric and volumetric storage capacity. We have been able to optimize these parameters for high hydrogen storage. All monolith uptakes (up to 260 bar) were measured by a custom-built, volumetric, reservoir-type instrument.

  19. Origin of the smaller conductances of Rh, Pb, and Co atomic junctions in hydrogen environment

    Science.gov (United States)

    Li, Xue; Chen, Mingyan; Ye, Xiang; Xie, Yi-qun; Ke, San-huang

    2015-02-01

    We study theoretically the structural and electronic origins of the smaller conductances (one conductance quantum, G0, and smaller) of Rh, Pb, and Co metal atomic junctions (MAJs) in a hydrogen environment, as were measured in recent experiments. For the Rh MAJs, the 1G0 conductance is attributed to a stable contact bridged by a single hydrogen molecule whose antibonding state provides a single transport channel. For the Pb and Co MAJs the 1G0 conductance is, however, ascribed to a linear atomic chain adsorbing two dissociated H atoms, which largely reduces the density of states at the Fermi energy with respect to the pure ones. On the other hand, the small conductances of 0.3G0 (Rh) and 0.2G0 (Co) are due to H-decorated atomic chains connected to electrodes by a H atom.

  20. Origin of the smaller conductances of Rh, Pb, and Co atomic junctions in hydrogen environment

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xue; Chen, Mingyan; Ye, Xiang; Xie, Yi-qun, E-mail: yqxie@shnu.edu.cn [Department of Physics, Shanghai Normal University, 100 Guilin Road, Shanghai 200232 (China); Ke, San-huang, E-mail: shke@tongji.edu.cn [MOE Key Laboratory of Advanced Microstructured Materials, School of Physics Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China)

    2015-02-14

    We study theoretically the structural and electronic origins of the smaller conductances (one conductance quantum, G{sub 0}, and smaller) of Rh, Pb, and Co metal atomic junctions (MAJs) in a hydrogen environment, as were measured in recent experiments. For the Rh MAJs, the 1G{sub 0} conductance is attributed to a stable contact bridged by a single hydrogen molecule whose antibonding state provides a single transport channel. For the Pb and Co MAJs the 1G{sub 0} conductance is, however, ascribed to a linear atomic chain adsorbing two dissociated H atoms, which largely reduces the density of states at the Fermi energy with respect to the pure ones. On the other hand, the small conductances of 0.3G{sub 0} (Rh) and 0.2G{sub 0} (Co) are due to H-decorated atomic chains connected to electrodes by a H atom.

  1. Improvement of saturation magnetization of Fe nanoparticles by post-annealing in a hydrogen gas atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Kin, Masane, E-mail: masane-kin@denso.co.jp; Tanaka, Masaaki; Hayashi, Yasushi; Hasaegawa, Jun [Research Laboratories, DENSO CORPORATION, 500-1, Minamiyama, Komenoki-cho, Nisshin, Aichi 470-0111 (Japan); Kura, Hiroaki; Ogawa, Tomoyuki [Department of Electronic Engineering, Graduate School of Engineering, Tohoku University, 6-6-05 Aza-Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

    2015-05-07

    Fe nanoparticles (NPs) were synthesized by the thermal decomposition of Fe(CO){sub 5} and then post-annealing in a hydrogen gas atmosphere to produce highly monodisperse Fe NPs with high saturation magnetization (M{sub s}). The as-synthesized pre-anneal Fe NPs had an expanded α-Fe structure and M{sub s} was only 39% of that for bulk Fe because of the low crystallinity and the inclusion of a surfactant. Post-annealing of the Fe NPs in a hydrogen gas atmosphere at 200 °C improved the crystallinity of the Fe NPs from an amorphous-like structure to a body centered cubic (bcc) structure without any lattice expansion. This result indicates that hydrogen gas plays a significant role in improvement of the crystallinity of Fe NPs. Accompanying the improvement in crystallinity, M{sub s} for the Fe NPs increased from 86 to 190 emu/g{sub net} at 300 K, the values of which include the weight of surfactant. This enhanced M{sub s} is almost the same as that of bulk Fe (218 emu/{sub Fe}). It was concluded that the crystallinity has a significant influence on the M{sub s} of the Fe NPs because long-range ordering of the lattice can maintain strong direct exchange interactions between Fe atoms.

  2. LOX vaporization in high-pressure, hydrogen-rich gas

    Science.gov (United States)

    Litchford, Ron J.; Jeng, San-Mou

    1990-01-01

    LOX droplet vaporization in high-pressure hydrogen-rich gas is analyzed, with special attention to thermodynamic effects which compel the surface to heat to the critical state and to supercritical vaporization processes on heating to criticality. Subcritical vaporization is modeled using a quasi-steady diffusion-controlled gas-phase transport formulation coupled to an effective-conductivity internal-energy-transport model accounting for circulation effects. It is demonstrated how the droplet surface might heat to the critical state, for ambient pressures slightly greater than the critical pressure of oxygen, such that the bulk of propellant within the droplet remains substantially below the critical mixing temperature.

  3. xGASS: Total cold gas scaling relations and molecular-to- atomic gas ratios of galaxies in the local Universe

    Science.gov (United States)

    Catinella, Barbara; Saintonge, Amélie; Janowiecki, Steven; Cortese, Luca; Davé, Romeel; Lemonias, Jenna J.; Cooper, Andrew P.; Schiminovich, David; Hummels, Cameron B.; Fabello, Silvia; Geréb, Katinka; Kilborn, Virginia; Wang, Jing

    2018-01-01

    We present the extended GALEX Arecibo SDSS Survey (xGASS), a gas fraction-limited census of the atomic hydrogen (HI) gas content of 1179 galaxies selected only by stellar mass (M⋆=109 - 1011.5 M⊙) and redshift (0.01 < z < 0.05). This includes new Arecibo observations of 208 galaxies, for which we release catalogs and HI spectra. In addition to extending the GASS HI scaling relations by one decade in stellar mass, we quantify total (atomic+molecular) cold gas fractions and molecular-to-atomic gas mass ratios, Rmol, for the subset of 477 galaxies observed with the IRAM 30 m telescope. We find that atomic gas fractions keep increasing with decreasing stellar mass, with no sign of a plateau down to log M⋆/M⊙ = 9. Total gas reservoirs remain HI-dominated across our full stellar mass range, hence total gas fraction scaling relations closely resemble atomic ones, but with a scatter that strongly correlates with Rmol, especially at fixed specific star formation rate. On average, Rmol weakly increases with stellar mass and stellar surface density μ⋆, but individual values vary by almost two orders of magnitude at fixed M⋆ or μ⋆. We show that, for galaxies on the star-forming sequence, variations of Rmol are mostly driven by changes of the HI reservoirs, with a clear dependence on μ⋆. Establishing if galaxy mass or structure plays the most important role in regulating the cold gas content of galaxies requires an accurate separation of bulge and disk components for the study of gas scaling relations.

  4. Derived properties from the dipole and generalized oscillator strength distributions of an endohedral confined hydrogen atom

    Science.gov (United States)

    Martínez-Flores, C.; Cabrera-Trujillo, R.

    2018-03-01

    We report the electronic properties of a hydrogen atom confined by a fullerene molecule by obtaining the eigenvalues and eigenfunctions of the time-independent Schrödinger equation by means of a finite-differences approach. The hydrogen atom confinement by a C60 fullerene cavity is accounted for by two model potentials: a square-well and a Woods–Saxon. The Woods–Saxon potential is implemented to study the role of a smooth cavity on the hydrogen atom generalized oscillator strength distribution. Both models characterize the cavity by an inner radius R 0, thickness Δ, and well depth V 0. We use two different values for R 0 and Δ, found in the literature, that characterize H@C60 to analyze the role of the fullerene cage size and width. The electronic properties of the confined hydrogen atom are reported as a function of the well depth V 0, emulating different electronic configurations of the endohedral cavity. We report results for the hyper-fine splitting, nuclear magnetic screening, dipole oscillator strength, the static and dynamic polarizability, mean excitation energy, photo-ionization, and stopping cross section for the confined hydrogen atom. We find that there is a critical potential well depth value around V 0 = 0.7 a.u. for the first set of parameters and around V 0 = 0.9 a.u. for the second set of parameters, which produce a drastic change in the electronic properties of the endohedral hydrogen system. These values correspond to the first avoided crossing on the energy levels. Furthermore, a clear discrepancy is found between the square-well and Woods–Saxon model potential results on the hydrogen atom generalized oscillator strength due to the square-well discontinuity. These differences are reflected in the stopping cross section for protons colliding with H@C60.

  5. The opening of the nationwide movement against atomic and hydrogen bombs in Japan : On the signature campaign against atomic and hydrogen bombs in 1954

    OpenAIRE

    宇吹, 暁

    1982-01-01

    The Signature Campaign against Atomic and Hydrogen bombs in 1954 caused the nationwide movement against A- and H-bombs in Japan. The purpose of this paper is to explicate characteristics of the Japanese movement against A- and H-bombs through the examination of the Signature Campaign. Especially, this paper tries to show the following four points. 1. When the crew of the Daigo-Fukuryumaru received heavy doses of radiation in the hydrogen bomb test conducted by the United states on Bikini Atol...

  6. Gas Phase Hydrogenation of Levulinic Acid to gamma-Valerolactone

    NARCIS (Netherlands)

    Bonrath, Werner; Castelijns, Anna Maria Cornelia Francisca; de Vries, Johannes Gerardus; Guit, Rudolf Philippus Maria; Schuetz, Jan; Sereinig, Natascha; Vaessen, Henricus Wilhelmus Leonardus Marie

    The gas phase hydrogenation of levulinic acid to gamma-valerolactone over copper and ruthenium based catalysts in a continuous fixed-bed reactor system was investigated. Among the catalysts a copper oxide based one [50-75 % CuO, 20-25 % SiO2, 1-5 % graphite, 0.1-1 % CuCO3/Cu(OH)(2)] gave

  7. Warm Pressurant Gas Effects on the Liquid Hydrogen Bubble Point

    Science.gov (United States)

    Hartwig, Jason W.; McQuillen, John B.; Chato, David J.

    2013-01-01

    This paper presents experimental results for the liquid hydrogen bubble point tests using warm pressurant gases conducted at the Cryogenic Components Cell 7 facility at the NASA Glenn Research Center in Cleveland, Ohio. The purpose of the test series was to determine the effect of elevating the temperature of the pressurant gas on the performance of a liquid acquisition device. Three fine mesh screen samples (325 x 2300, 450 x 2750, 510 x 3600) were tested in liquid hydrogen using cold and warm noncondensible (gaseous helium) and condensable (gaseous hydrogen) pressurization schemes. Gases were conditioned from 0 to 90 K above the liquid temperature. Results clearly indicate a degradation in bubble point pressure using warm gas, with a greater reduction in performance using condensable over noncondensible pressurization. Degradation in the bubble point pressure is inversely proportional to screen porosity, as the coarsest mesh demonstrated the highest degradation. Results here have implication on both pressurization and LAD system design for all future cryogenic propulsion systems. A detailed review of historical heated gas tests is also presented for comparison to current results.

  8. Experimental Study of Gas Explosions in Hydrogen Sulfide-Natural Gas-Air Mixtures

    Directory of Open Access Journals (Sweden)

    André Vagner Gaathaug

    2014-01-01

    Full Text Available An experimental study of turbulent combustion of hydrogen sulfide (H2S and natural gas was performed to provide reference data for verification of CFD codes and direct comparison. Hydrogen sulfide is present in most crude oil sources, and the explosion behaviour of pure H2S and mixtures with natural gas is important to address. The explosion behaviour was studied in a four-meter-long square pipe. The first two meters of the pipe had obstacles while the rest was smooth. Pressure transducers were used to measure the combustion in the pipe. The pure H2S gave slightly lower explosion pressure than pure natural gas for lean-to-stoichiometric mixtures. The rich H2S gave higher pressure than natural gas. Mixtures of H2S and natural gas were also studied and pressure spikes were observed when 5% and 10% H2S were added to natural gas and also when 5% and 10% natural gas were added to H2S. The addition of 5% H2S to natural gas resulted in higher pressure than pure H2S and pure natural gas. The 5% mixture gave much faster combustion than pure natural gas under fuel rich conditions.

  9. Elastic scattering of positrons off rare-gas atoms

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, S.; Talukdar, B. (Department of Physics, Visva-Bharati University, Santiniketan-731 235 (India)); Mandal, P. (Department of Mathematics, Visva-Bharati University, Santiniketan-731 235 (India))

    1995-01-01

    A simple potential model proposed for the elastic scattering of positrons off rare-gas atoms is used to compute low-energy phase shifts and differential scattering cross sections [sigma]([theta]) for positrons incident on [sub 10]Ne, [sub 18]Ar, and [sub 36]Kr at energies 20, 3.4, and 6.67 eV, respectively. The calculated results for [sigma]([theta]) are in good agreement with currently available experimental values and are as reliable as the numbers obtained from much more elaborate calculations. It is pointed out that an important virtue of the present model is its simplicity.

  10. 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.

  11. Integrated Micro-Machined Hydrogen Gas Sensor. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Frank DiMeo, Jr.

    2000-10-02

    This report details our recent progress in developing novel MEMS (Micro-Electro-Mechanical Systems) based hydrogen gas sensors. These sensors couple novel thin films as the active layer on a device structure known as a Micro-HotPlate. This coupling has resulted in a gas sensor that has several unique advantages in terms of speed, sensitivity, stability and amenability to large scale manufacture. This Phase-I research effort was focused on achieving the following three objectives: (1) Investigation of sensor fabrication parameters and their effects on sensor performance. (2) Hydrogen response testing of these sensors in wet/dry and oxygen-containing/oxygen-deficient atmospheres. (3) Investigation of the long-term stability of these thin film materials and identification of limiting factors. We have made substantial progress toward achieving each of these objectives, and highlights of our phase I results include the demonstration of signal responses with and without oxygen present, as well as in air with a high level of humidity. We have measured response times of <0.5 s to 1% H{sub 2} in air, and shown the ability to detect concentrations of <200 ppm. These results are extremely encouraging and suggest that this technology has substantial potential for meeting the needs of a hydrogen based economy. These achievements demonstrate the feasibility of using micro-hotplates structures in conjunction with palladium+coated metal-hydride films for sensing hydrogen in many of the environments required by a hydrogen based energy economy. Based on these findings, they propose to continue and expand the development of this technology in Phase II.

  12. Hydrogen sulphide in cardiovascular system: A cascade from interaction between sulphur atoms and signalling molecules.

    Science.gov (United States)

    Wang, Ming-Jie; Cai, Wen-Jie; Zhu, Yi-Chun

    2016-05-15

    As a gasotransmitter, hydrogen sulphide exerts its extensive physiological and pathophysiological effects in mammals. The interaction between sulphur atoms and signalling molecules forms a cascade that modulates cellular functions and homeostasis. In this review, we focus on the signalling mechanism underlying the effect of hydrogen sulphide in the cardiovascular system and metabolism as well as the biological relevance to human diseases. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Nucleon polarizabilities: From Compton scattering to hydrogen atom

    OpenAIRE

    Hagelstein, Franziska; Miskimen, Rory; Pascalutsa, Vladimir

    2016-01-01

    We review the current state of knowledge of the nucleon polarizabilities and of their role in nucleon Compton scattering and in hydrogen spectrum. We discuss the basic concepts, the recent lattice QCD calculations and advances in chiral effective-field theory. On the experimental side, we review the ongoing programs aimed to measure the nucleon (scalar and spin) polarizabilities via the Compton scattering processes, with real and virtual photons. A great part of the review is devoted to the g...

  14. Exciting Nucleons in Compton Scattering and Hydrogen-Like Atoms

    OpenAIRE

    Hagelstein, Franziska

    2017-01-01

    This PhD thesis is devoted to the low-energy structure of the nucleon (proton and neutron) as seen through electromagnetic probes, e.g., electron and Compton scattering. The research presented here is based primarily on dispersion theory and chiral effective-field theory. The main motivation is the recent proton radius puzzle, which is the discrepancy between the classic proton charge radius determinations (based on electron-proton scattering and normal hydrogen spectroscopy) and the highly p...

  15. Surface Magnetism of Cobalt Nanoislands Controlled by Atomic Hydrogen.

    Science.gov (United States)

    Park, Jewook; Park, Changwon; Yoon, Mina; Li, An-Ping

    2017-01-11

    Controlling the spin states of the surface and interface is key to spintronic applications of magnetic materials. Here, we report the evolution of surface magnetism of Co nanoislands on Cu(111) upon hydrogen adsorption and desorption with the hope of realizing reversible control of spin-dependent tunneling. Spin-polarized scanning tunneling microscopy reveals three types of hydrogen-induced surface superstructures, 1H-(2 × 2), 2H-(2 × 2), and 6H-(3 × 3), with increasing H coverage. The prominent magnetic surface states of Co, while being preserved at low H coverage, become suppressed as the H coverage level increases, which can then be recovered by H desorption. First-principles calculations reveal the origin of the observed magnetic surface states by capturing the asymmetry between the spin-polarized surface states and identify the role of hydrogen in controlling the magnetic states. Our study offers new insights into the chemical control of magnetism in low-dimensional systems.

  16. An algebraic SU(1,1) solution for the relativistic hydrogen atom

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-y-Romero, R.P. [Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, Apartado Postal 21-267, CP 04000, Coyoacan DF (Mexico)]. E-mail: rmr@hp.fciencias.unam.mx; Nunez-Yepez, H.N. [Departamento de Fisica, Universidad Autonoma Metropolitana, Unidad Iztapalapa, Apartado Postal 55-534, CP 09340, Iztapalapa DF (Mexico)]. E-mail: nyhn@xanum.uam.mx; Salas-Brito, A.L. [Laboratorio de Sistemas Dinamicos, Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana, Unidad Azcapotzalco, Apartado Postal 21-267, CP 04000, Coyoacan DF (Mexico)]. E-mail: asb@correo.azc.uam.mx

    2005-05-23

    The bound eigenfunctions and spectrum of a Dirac hydrogen atom are found taking advantage of the SU(1,1) Lie algebra in which the radial part of the problem can be expressed. For defining the algebra we need to add to the description an additional angular variable playing essentially the role of a phase. The operators spanning the algebra are used for defining ladder operators for the radial eigenfunctions of the relativistic hydrogen atom and for evaluating its energy spectrum. The status of the Johnson-Lippman operator in this algebra is also investigated.

  17. Ground state of the hydrogen atom via Dirac equation in a minimal-length scenario

    Energy Technology Data Exchange (ETDEWEB)

    Antonacci Oakes, T.L.; Francisco, R.O.; Fabris, J.C.; Nogueira, J.A. [Universidade Federal do Espirito Santo, Departamento de Fisica, Vitoria (Brazil)

    2013-07-15

    In this work we calculate the correction to the ground state energy of the hydrogen atom due to contributions arising from the presence of a minimal length. The minimal-length scenario is introduced by means of modifying the Dirac equation through a deformed Heisenberg algebra (Kempf algebra). With the introduction of the Coulomb potential in the new Dirac energy operator, we calculate the energy shift of the ground state of the hydrogen atom in first order of the parameter related to the minimal length via perturbation theory. (orig.)

  18. Hydrogen trapping by solute atoms in Nb-Mo alloys as observed by the channelling method

    Energy Technology Data Exchange (ETDEWEB)

    Yagi, Eiichi; Nakamura, Shiho; Kano, Fumihisa; Kobayashi, Takane (Institute of Physical and Chemical Research, Wako, Saitama (Japan)); Watanabe, Kenyi; Fukai, Yuh (Chuo Univ., Tokyo (Japan). Dept. of Physics); Matsumoto, Takehiko (National Research Inst. for Metals, Tokyo (Japan))

    1989-01-01

    The enhancement of the terminal solubility for hydrogen (TSH) in group Va metals (V, Nb and Ta) on alloying with metal solute atoms has been reported for various alloying elements. To elucidate the mechanism of this enhancement, in the present study the lattice location of hydrogen was investigated by the channeling method using a nuclear reaction {sup 1}H({sup 11}B,{alpha}){alpha}{alpha} on the Nb alloys containing undersized Mo atoms (Nb-3at%Mo alloys). (orig./MM).

  19. The long-range interaction in the scattering of positronium by hydrogen atoms

    Science.gov (United States)

    Meredith, D. G.; Fraser, P. A.

    2018-03-01

    Elastic scattering of positronium by hydrogen atoms is investigated. A method is devised wherein the effects of the long-range van der Waals attraction between the two atoms are accurately incorporated into a trial wave function in the form of a pseudo-state. The properly adjusted trial function yields a van der Waals coefficient that is within 0.03% of the known value. Improved phase shifts in the absence of exchange are reported.

  20. Shared symmetries of the hydrogen atom and the two-bit system

    Science.gov (United States)

    Rau, A. R. P.; Alber, G.

    2017-12-01

    The hydrogen atom is the simplest system of atomic and molecular physics, while a two-qubit system is the simplest of quantum information. Remarkably, they share common symmetry aspects which are described in this paper, based on a correspondence between the four-dimensional unitary group and the six-dimensional rotational group with its non-compact extensions. Both systems involve 15 basic operators. Reductions to Lorentz and Poincare space–time group symmetries of a free particle are also discussed.

  1. Behavior of hydrogen atoms in boron films during H{sub 2} and He glow discharge and thermal desorption

    Energy Technology Data Exchange (ETDEWEB)

    Tsuzuki, K.; Natsir, M.; Inoue, N. [and others

    1995-09-01

    Hydrogen absorption and desorption characteristics in boron films deposited on a graphite liner have been studied. Number of hydrogen atoms absorbed in the films is estimated from a decrease in hydrogen pressure during a hydrogen glow discharge. It was 1.9 x 10{sup 17} atoms/cm{sup 2} in the 1 hour discharge after an evacuation of H atoms contained in the original boron films by thermal desorption. Hydrogen atoms were absorbed continuously without saturation for 3 hours during the discharge. Number of H atoms absorbed reached to 2.6 x 10{sup 17} atoms/cm{sup 2} at 3 hour. A discharge in helium was carried out to investigate H desorption characteristics from hydrogen implanted boron films. It was verified that reactivity for hydrogen absorption was recovered after the He discharge. Hydrogen atoms were accumulated in the films by repetition of alternate He and H{sub 2} discharge. Thermal desorption experiments have been carried out by raising the liner temperature up to 500degC for films after 1 hour, 3 hours hydrogen discharge and 6 times repetition of H{sub 2}/He discharges. Most of H atoms in the films were desorbed for all these cases. The slow absorption process was confirmed through the thermal desorption experiments. (author).

  2. Atomic hydrogen induced defect kinetics in amorphous silicon

    NARCIS (Netherlands)

    Peeters, F. J. J.; Zheng, J.; Aarts, I. M. P.; Pipino, A. C. R.; Kessels, W. M. M.; van de Sanden, M. C. M.

    2017-01-01

    Near-infrared evanescent-wave cavity ring-down spectroscopy (CRDS) has been applied to study the defect evolution in an amorphous silicon (a-Si:H) thin film subjected to a directed beam of atomic H with a flux of (0.4–2) × 1014 cm−2 s−1. To this end, a 42 ± 2 nm a-Si:H film was grown on the total

  3. Methane Formation by Flame-Generated Hydrogen Atoms in the Flame Ionization Detector

    DEFF Research Database (Denmark)

    Holm, Torkil; Madsen, Jørgen Øgaard

    1996-01-01

    The precombustion degradation of organic compounds in the flame ionization detector has been studied (1) by heating the additives in hydrogen in a quartz capillary and analyzing the reaction products by GC and (2) by following the degradation of the additives in a hydrogen flame, by means of a thin......, and conceivably all hydrocarbons are quantitatively converted into methane at temperatures below 600 C, that is, before the proper combustion has started. The splitting of the C-C bonds is preceded by hydrogenation of double and triple bonds and aromatic rings. The reactions, no doubt, are caused by hydrogen...... atoms, which are formed in the burning hydrogen and which diffuse into the inner core of the flame. The quantitative formation of methane appears to explain the "equal per carbon" rule for the detector response of hydrocarbons, since all carbons are "exchanged" for methane molecules....

  4. Stability of gas atomized reactive powders through multiple step in-situ passivation

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver E.; Steinmetz, Andrew D.; Byrd, David J.

    2017-05-16

    A method for gas atomization of oxygen-reactive reactive metals and alloys wherein the atomized particles are exposed as they solidify and cool in a very short time to multiple gaseous reactive agents for the in-situ formation of a protective reaction film on the atomized particles. The present invention is especially useful for making highly pyrophoric reactive metal or alloy atomized powders, such as atomized magnesium and magnesium alloy powders. The gaseous reactive species (agents) are introduced into the atomization spray chamber at locations downstream of a gas atomizing nozzle as determined by the desired powder or particle temperature for the reactions and the desired thickness of the reaction film.

  5. Method of generating hydrogen gas from sodium borohydride

    Science.gov (United States)

    Kravitz, Stanley H.; Hecht, Andrew M.; Sylwester, Alan P.; Bell, Nelson S.

    2007-12-11

    A compact solid source of hydrogen gas, where the gas is generated by contacting water with micro-disperse particles of sodium borohydride in the presence of a catalyst, such as cobalt or ruthenium. The micro-disperse particles can have a substantially uniform diameter of 1-10 microns, and preferably about 3-5 microns. Ruthenium or cobalt catalytic nanoparticles can be incorporated in the micro-disperse particles of sodium borohydride, which allows a rapid and complete reaction to occur without the problems associated with caking and scaling of the surface by the reactant product sodium metaborate. A closed loop water management system can be used to recycle wastewater from a PEM fuel cell to supply water for reacting with the micro-disperse particles of sodium borohydride in a compact hydrogen gas generator. Capillary forces can wick water from a water reservoir into a packed bed of micro-disperse fuel particles, eliminating the need for using an active pump.

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

    Science.gov (United States)

    2009-04-20

    2007). DOI: 10.1021/jp0744811 16 Oxidative dehydrogenation of methanol to formaldehyde by isolated vanadium, molybdenum , and chromium oxide clusters...composite Some ZrB2-metal composites can form new boride phases during laser processing, especially when binder materials possess similar chemical...properties to Zr. We have observed the formation of new boride phases when Ti and Ta binder materials are used. Figure 8 shows TiB fibers spread

  7. Sticking probability for hydrogen atoms on the surface of liquid /sup 4/He

    Energy Technology Data Exchange (ETDEWEB)

    Zimmerman, D.S.; Berlinsky, A.J.

    1983-03-01

    A calculation is presented of the sticking probability for hydrogen atoms colliding with a liquid /sup 4/He surface. The calculation is based on a model potential for the H-liquid /sup 4/He interaction which is used to derive both bound and free atom wave function and the linear H atom-ripplon coupling. Results are presented in terms of the energy and angle dependent sticking probability s(E,THETA) and the thermally averaged probability s(T), and comparison is made to the experimental results s(T)=0.035 +-0.00 for 0.18 < T < 0.27 K.

  8. Low-energy measurements of electron capture by multicharged ions from excited hydrogen atoms

    Energy Technology Data Exchange (ETDEWEB)

    Havener, C.C. (Oak Ridge National Laboratory, Oak Ridge, Tennesse 37831-6372 (United States)); Haque, M.A. (Alcorn State University, Lorman, Mississippi 39096 (United States)); Smith, A.C.H. (University College London, WC1E 6BT (United Kingdom)); Urbain, X. (Universite Catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve (Belgium)); Zeijlmans van Emmichoven, P.A. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6372 (United States) Joint Institute for Heavy Ion Research, Holifield Heavy Ion Research Facility, Oak Ridge, Tennessee 37831-6374 (United States))

    1993-06-05

    For very low collision energies electron capture from excited hydrogen by multicharged ions is characterized by enormous cross sections, the predicted maximum being comparable to the geometric size of the Rydberg atom. The ion-atom merged-beams technique is being used to study these collisions for the variety of charge states and the wide range of energies (0.1 to 1000 eV/amu) accessible to the apparatus. A neutral D beam containing a Rydberg atom population proportional to 1/n[sup 3] is produced by collisional electron detachment of 8 keV D[sup [minus

  9. Selective permeation of hydrogen gas using cellulose nanofibril film.

    Science.gov (United States)

    Fukuzumi, Hayaka; Fujisawa, Shuji; Saito, Tsuguyuki; Isogai, Akira

    2013-05-13

    Biobased membranes that can selectively permeate hydrogen gas have been developed from aqueous dispersions of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCN) prepared from wood cellulose: TOCN-coated plastic films and self-standing TOCN films. Compared with TOCNs with sodium, lithium, potassium, and cesium carboxylate groups, TOCN with free carboxyl groups (TOCN-COOH) had much high and selective H2 gas permeation performance. Because permeabilities of H2, N2, O2, and CO2 gases through the membranes primarily depended on their kinetic diameters, the gas permeation behavior of the various TOCNs can be explained in terms of a diffusion mechanism. Thus, the selective H2 gas permeability for TOCN-COOH was probably due to a larger average size in free volume holes present between nanofibrils in the layer and film than those of other TOCNs with metal carboxylate groups. The obtained results indicate that TOCN-COOH membranes are applicable as biobased H2 gas separation membranes in fuel cell electric power generation systems.

  10. Synergistic Formation of Radicals by Irradiation with Both Vacuum Ultraviolet and Atomic Hydrogen: A Real-Time In Situ Electron Spin Resonance Study

    CERN Document Server

    Ishikawa, Kenji; Kono, Akihiko; Horibe, Hideo; Takeda, Keigo; Kondo, Hiroki; Sekine, Makoto; Hori, Masaru; 10.1021/jz2002937

    2012-01-01

    We report on the surface modification of polytetrafluoroethylene (PTFE) as an example of soft- and bio-materials that occur under plasma discharge by kinetics analysis of radical formation using in situ real-time electron spin resonance (ESR) measurements. During irradiation with hydrogen plasma, simultaneous measurements of the gas-phase ESR signals of atomic hydrogen and the carbon dangling bond (C-DB) on PTFE were performed. Dynamic changes of the C-DB density were observed in real time, where the rate of density change was accelerated during initial irradiation and then became constant over time. It is noteworthy that C-DBs were formed synergistically by irradiation with both vacuum ultraviolet (VUV) and atomic hydrogen. The in situ real-time ESR technique is useful to elucidate synergistic roles during plasma surface modification.

  11. Learning about Regiochemistry from a Hydrogen-Atom Abstraction Reaction in Water

    Science.gov (United States)

    Sears-Dundes, Christopher; Huon, Yoeup; Hotz, Richard P.; Pinhas, Allan R.

    2011-01-01

    An experiment has been developed in which the hydrogen-atom abstraction and the coupling of propionitrile, using Fenton's reagent, are investigated. Students learn about the regiochemistry of radical formation, the stereochemistry of product formation, and the interpretation of GC-MS data, in a safe reaction that can be easily completed in one…

  12. Quantum dynamics of hydrogen atoms on graphene. I. System-bath modeling

    Energy Technology Data Exchange (ETDEWEB)

    Bonfanti, Matteo, E-mail: matteo.bonfanti@unimi.it [Dipartimento di Chimica, Università degli Studi di Milano, v. Golgi 19, 20133 Milano (Italy); Jackson, Bret [Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003 (United States); Hughes, Keith H. [School of Chemistry, Bangor University, Bangor, Gwynedd LL57 2UW (United Kingdom); Burghardt, Irene [Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt/Main (Germany); Martinazzo, Rocco, E-mail: rocco.martinazzo@unimi.it [Dipartimento di Chimica, Università degli Studi di Milano, v. Golgi 19, 20133 Milano (Italy); Istituto di Scienze e Tecnologie Molecolari, Consiglio Nazionale delle Richerche, v. Golgi 19, 20133 Milano (Italy)

    2015-09-28

    An accurate system-bath model to investigate the quantum dynamics of hydrogen atoms chemisorbed on graphene is presented. The system comprises a hydrogen atom and the carbon atom from graphene that forms the covalent bond, and it is described by a previously developed 4D potential energy surface based on density functional theory ab initio data. The bath describes the rest of the carbon lattice and is obtained from an empirical force field through inversion of a classical equilibrium correlation function describing the hydrogen motion. By construction, model building easily accommodates improvements coming from the use of higher level electronic structure theory for the system. Further, it is well suited to a determination of the system-environment coupling by means of ab initio molecular dynamics. This paper details the system-bath modeling and shows its application to the quantum dynamics of vibrational relaxation of a chemisorbed hydrogen atom, which is here investigated at T = 0 K with the help of the multi-configuration time-dependent Hartree method. Paper II deals with the sticking dynamics.

  13. A theoretical perspective of the nature of hydrogen-bond types - the atoms in molecules approach

    Czech Academy of Sciences Publication Activity Database

    Pandiyan, B. V.; Kolandaivel, P.; Deepa, Palanisamy

    2014-01-01

    Roč. 112, č. 12 (2014), s. 1609-1623 ISSN 0026-8976 Institutional support: RVO:61388963 Keywords : hydrogen bond * proton affinity * deprotanation enthalpy * atoms in molecules * chemical shift Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.720, year: 2014

  14. Relativistic Approach to the Hydrogen Atom in a Minimal Length Scenario

    Energy Technology Data Exchange (ETDEWEB)

    Francisco, Ronald Oliveira; Oakes, Thiago Luiz Antonacci; Fabris, Julio Cesar; Nogueira, Jose Alexandre, E-mail: jose.nogueira@ufes.br [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Departamento de Fisica

    2014-07-01

    We show that relativistic contributions to the ground-state energy of the hydrogen atom from a minimal length introduced by a Lorentz-covariant algebra are more important than non-relativistic contributions; the nonrelativistic approach is therefore unsuitable. We compare our result with experimental data to estimate an upper bound of the order 10{sup -20}m for the minimal length. (author)

  15. High-magnetic-field-assisted scattering of electrons with atomic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Ajoy [Laban Hrad Vidyapith, AD-369, Salt Lake City, Kolkata 700064 (India)

    2007-04-28

    We have investigated quantum mechanically the scattering of electrons off atomic hydrogen in a strong magnetic field. Elastic, inelastic, backward and total scattering cross sections are reported. Near-resonance behaviour of the system is analysed. Results are presented after evaluating and summing all-order Born series under suitable physical conditions.

  16. Laboratory Measurements of Charge Transfer on Atomic Hydrogen at Thermal Energies

    Science.gov (United States)

    Havener, C. C.; Vane, C. R.; Krause, H. F.; Stancil, P. C.; Mroczkowski, T.; Savin, D. W.

    2002-01-01

    We describe our ongoing program to measure velocity dependent charge transfer (CT) cross sections for selected ions on atomic hydrogen using the ion-aloin merged-beams apparatus at Oak Ridge Natioiial Laboralory. Our focus is on those ions for which CT plays an important role in determining the ionization structure, line emis sion, and thermal structure of observed cosmic photoionized plasmas.

  17. Most Typical 12 Resonant Perturbation of the Hydrogen Atom by Weak Electric and Magnetic Fields

    NARCIS (Netherlands)

    Efstathiou, K.; Lukina, O. V.; Sadovskii, D. A.

    2008-01-01

    We study a perturbation of the hydrogen atom by small homogeneous static electric and magnetic fields in a specific mutual alignment with angle approximately pi/3 which results in the 12 resonance of the linearized Keplerian n-shell approximation. The bifurcation diagram of the classical integrable

  18. Effect of vacuum polarization on the excitation of hydrogen atom by electron impact

    Directory of Open Access Journals (Sweden)

    Sujata Bhattacharyya

    1981-01-01

    for 1S−2S excitation of the hydrogen atom by electron impact. The excitation amplitude calculated field theoretically is found to be lowered by 0.47t2/(t2+93 where t2=4|P−Q|2, P and Q being the momenta of the incident and scattered electrons respectively.

  19. Insights into the Electronic Structure of Ozone and Sulfur Dioxide from Generalized Valence Bond Theory: Addition of Hydrogen Atoms.

    Science.gov (United States)

    Lindquist, Beth A; Takeshita, Tyler Y; Dunning, Thom H

    2016-05-05

    Ozone (O3) and sulfur dioxide (SO2) are valence isoelectronic species, yet their properties and reactivities differ dramatically. In particular, O3 is highly reactive, whereas SO2 is chemically relatively stable. In this paper, we investigate serial addition of hydrogen atoms to both the terminal atoms of O3 and SO2 and to the central atom of these species. It is well-known that the terminal atoms of O3 are much more amenable to bond formation than those of SO2. We show that the differences in the electronic structure of the π systems in the parent triatomic species account for the differences in the addition of hydrogen atoms to the terminal atoms of O3 and SO2. Further, we find that the π system in SO2, which is a recoupled pair bond dyad, facilitates the addition of hydrogen atoms to the sulfur atom, resulting in stable HSO2 and H2SO2 species.

  20. Catalysts for selective oxidation of ammonia in a gas containing hydrogen

    DEFF Research Database (Denmark)

    2015-01-01

    The invention contributes to a cost effective way to solve the problem of trace ammonia removal from a hydrogen and nitrogen containing gas. The set of catalysts of the invention selectively oxidised ammonia in ppm concentration even in gas mixtures containing hydrogen gas in concentrations...

  1. Catalysts for selective oxidation of ammonia in a gas containing hydrogen

    DEFF Research Database (Denmark)

    2014-01-01

    The invention contributes to a cost effective way to solve the problem of trace ammonia removal from hydrogen containing gas. The set of catalysts of the invention selectively oxidised ammonia in ppm concentration even in gas mixture containing hydrogen gas in concentration of three orders...

  2. Gas atomization processing of tin and silicon modified lanthum-nickel for nickel-metal hydride battery applications

    Science.gov (United States)

    Ting, Jason

    Numerous researchers have studied the relevant material properties of so-called AB5 alloys for battery applications using conventional cast and crush alloy techniques. The previous works nearly ignored the potential for alternative direct powder production methods, like high pressure gas atomization (HPGA) that could reduce manufacturing cost of nickel-metal hydride powder. This work examined the relationship between gas atomization processes, powder particle solidification phases, and hydrogen absorption properties of ultra fine (316L stainless steel. This nozzle was demonstrated to produce a high yield of ultrafine powders that are essential for development of a direct production process for AB5 alloys for powders for battery applications. Rapid solidification by gas atomization of LaNi4.6Si 0.4 and LaNi4.85Sn0.15, LaNi4.75Sn 0.25 and LaNi5.5Sn0.3 alloys was studied. Small atomized particles (phase hydrogen cycling. Rapid annealing of the gasatomized AB 5 alloys at 900°C for 5 minutes was sufficient to fully remove quenched-in nonequilibrium substitution-rich phases La-Ni-Si and La-Ni-Sn alloys. During annealing, preferential diffusion paths for Sn were observed on {002} and {202} planes using XRD. The activation enthalpy and interdiffusion coefficient for tin diffusing in La(Ni,Sn)5 intermetallic were determined to be 152.24 KJ.mole-1 and 1.975 (10-6) cm 2. sec-1, respectively, using a simple isotropic diffusion model. 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.

  3. Mutual Neutralization of Atomic Rare-Gas Cations (Ne+, Ar+, Kr+, Xe+) with Atomic Halide Anions (Cl-, Br-, I-)

    Science.gov (United States)

    2015-01-07

    gas cations (Ne+, Ar+, Kr+, Xe+) with halide anions (Cl−, Br−, I−), comprising both mutual neutralization (MN) and transfer ionization. No rate...OF CHEMICAL PHYSICS 140, 044304 (2014) Mutual neutralization of atomic rare-gas cations (Ne+, Ar+, Kr+, Xe+) with atomic halide anions (Cl−, Br−, I... cations (Ne+, Ar+, Kr+, Xe+) with halide anions (Cl−, Br−, I−), comprising both mutual neutralization (MN) and transfer ionization. No rate coefficients

  4. 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 cosmic web and classification into filaments, walls, and voids) to investigate the influence of small and large-scale environment on galaxy gas content. We show that satellites in groups down to 1012 M⊙ have lower gas fractions compared to centrals at similar stellar mass, suggesting that 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.

  5. Electrical and Surface Properties of InAs/InSb Nanowires Cleaned by Atomic Hydrogen.

    Science.gov (United States)

    Webb, James L; Knutsson, Johan; Hjort, Martin; Gorji Ghalamestani, Sepideh; Dick, Kimberly A; Timm, Rainer; Mikkelsen, Anders

    2015-08-12

    We present a study of InAs/InSb heterostructured nanowires by X-ray photoemission spectroscopy (XPS), scanning tunneling microscopy (STM), and in-vacuum electrical measurements. Starting with pristine nanowires covered only by the native oxide formed through exposure to ambient air, we investigate the effect of atomic hydrogen cleaning on the surface chemistry and electrical performance. We find that clean and unreconstructed nanowire surfaces can be obtained simultaneously for both InSb and InAs by heating to 380 ± 20 °C under an H2 pressure 2 × 10(-6) mbar. Through electrical measurement of individual nanowires, we observe an increase in conductivity of 2 orders of magnitude by atomic hydrogen cleaning, which we relate through theoretical simulation to the contact-nanowire junction and nanowire surface Fermi level pinning. Our study demonstrates the significant potential of atomic hydrogen cleaning regarding device fabrication when high quality contacts or complete control of the surface structure is required. As hydrogen cleaning has recently been shown to work for many different types of III-V nanowires, our findings should be applicable far beyond the present materials system.

  6. Rotating disk atomization of Gd and Gd-Y for hydrogen liquefaction via magnetocaloric cooling

    Energy Technology Data Exchange (ETDEWEB)

    Slinger, Tyler [Iowa State Univ., Ames, IA (United States)

    2016-12-17

    In order to enable liquid hydrogen fuel cell technologies for vehicles the cost of hydrogen liquefaction should be lowered. The current method of hydrogen liquefaction is the Claude cycle that has a figure of merit (FOM) of 0.3-0.35. New magnetocaloric hydrogen liquefaction devices have been proposed with a FOM>0.5, which is a significant improvement. A significant hurdle to realizing these devices is the synthesis of spherical rare earth based alloy powders of 200μm in diameter. In this study a centrifugal atomization method that used a rotating disk with a rotating oil quench bath was developed to make gadolinium and gadolinium-yttrium spheres. The composition of the spherical powders included pure Gd and Gd0.91Y0.09. The effect of atomization parameters, such as superheat, melt properties, disk shape, disk speed, and melt system materials and design, were investigated on the size distribution and morphology of the resulting spheres. The carbon, nitrogen, and oxygen impurity levels also were analyzed and compared with the magnetic performance of the alloys. The magnetic properties of the charge material as well as the resulting powders were measured using a vibrating sample magnetometer. The saturation magnetization and Curie temperature were the target properties for the resulting spheres. These values were compared with measurements taken on the charge material in order to investigate the effect of atomization processing on the alloys.

  7. Overview of Two Hydrogen Energy Storage Studies: Wind Hydrogen in California and Blending in Natural Gas Pipelines (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Melaina, M. W.

    2013-05-01

    This presentation provides an overview of two NREL energy storage studies: Wind Hydrogen in California: Case Study and Blending Hydrogen Into Natural Gas Pipeline Networks: A Review of Key Issues. The presentation summarizes key issues, major model input assumptions, and results.

  8. Competition between Al2O3 atomic layer etching and AlF3 atomic layer deposition using sequential exposures of trimethylaluminum and hydrogen fluoride

    Science.gov (United States)

    DuMont, Jaime W.; George, Steven M.

    2017-02-01

    The thermal atomic layer etching (ALE) of Al2O3 can be performed using sequential and self-limiting reactions with trimethylaluminum (TMA) and hydrogen fluoride (HF) as the reactants. The atomic layer deposition (ALD) of AlF3 can also be accomplished using the same reactants. This paper examined the competition between Al2O3 ALE and AlF3 ALD using in situ Fourier transform infrared (FTIR) vibrational spectroscopy measurements on Al2O3 ALD-coated SiO2 nanoparticles. The FTIR spectra could observe an absorbance loss of the Al-O stretching vibrations during Al2O3 ALE or an absorbance gain of the Al-F stretching vibrations during AlF3 ALD. The transition from AlF3 ALD to Al2O3 ALE occurred versus reaction temperature and was also influenced by the N2 or He background gas pressure. Higher temperatures and lower background gas pressures led to Al2O3 ALE. Lower temperatures and higher background gas pressures led to AlF3 ALD. The FTIR measurements also monitored AlCH3* and HF* species on the surface after the TMA and HF reactant exposures. The loss of AlCH3* and HF* species at higher temperatures is believed to play a vital role in the transition between AlF3 ALD at lower temperatures and Al2O3 ALE at higher temperatures. The change between AlF3 ALD and Al2O3 ALE was defined by the transition temperature. Higher transition temperatures were observed using larger N2 or He background gas pressures. This correlation was associated with variations in the N2 or He gas thermal conductivity versus pressure. The fluorination reaction during Al2O3 ALE is very exothermic and leads to temperature rises in the SiO2 nanoparticles. These temperature transients influence the Al2O3 etching. The higher N2 and He gas thermal conductivities are able to cool the SiO2 nanoparticles more efficiently and minimize the size of the temperature rises. The competition between Al2O3 ALE and AlF3 ALD using TMA and HF illustrates the interplay between etching and growth and the importance of substrate

  9. 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.

  10. 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.

  11. Theoretical realization of cluster-assembled hydrogen storage materials based on terminated carbon atomic chains.

    Science.gov (United States)

    Liu, Chun-Sheng; An, Hui; Guo, Ling-Ju; Zeng, Zhi; Ju, Xin

    2011-01-14

    The capacity of carbon atomic chains with different terminations for hydrogen storage is studied using first-principles density functional theory calculations. Unlike the physisorption of H(2) on the H-terminated chain, we show that two Li (Na) atoms each capping one end of the odd- or even-numbered carbon chain can hold ten H(2) molecules with optimal binding energies for room temperature storage. The hybridization of the Li 2p states with the H(2)σ orbitals contributes to the H(2) adsorption. However, the binding mechanism of the H(2) molecules on Na arises only from the polarization interaction between the charged Na atom and the H(2). Interestingly, additional H(2) molecules can be bound to the carbon atoms at the chain ends due to the charge transfer between Li 2s2p (Na 3s) and C 2p states. More importantly, dimerization of these isolated metal-capped chains does not affect the hydrogen binding energy significantly. In addition, a single chain can be stabilized effectively by the C(60) fullerenes termination. With a hydrogen uptake of ∼10 wt.% on Li-coated C(60)-C(n)-C(60) (n = 5, 8), the Li(12)C(60)-C(n)-Li(12)C(60) complex, keeping the number of adsorbed H(2) molecules per Li and stabilizing the dispersion of individual Li atoms, can serve as better building blocks of polymers than the (Li(12)C(60))(2) dimer. These findings suggest a new route to design cluster-assembled hydrogen storage materials based on terminated sp carbon chains.

  12. [Measurement of atomic number of alkali vapor and pressure of buffer gas based on atomic absorption].

    Science.gov (United States)

    Zheng, Hui-jie; Quan, Wei; Liu, Xiang; Chen, Yao; Lu, Ji-xi

    2015-02-01

    High sensitivitymagnetic measurementscanbe achieved by utilizing atomic spinmanipulation in the spin-exchange-relaxation-free (SERF) regime, which uses an alkali cell as a sensing element. The atomic number density of the alkali vapor and the pressure of the buffer gasare among the most important parameters of the cell andrequire accurate measurement. A method has been proposed and developedto measure the atomic number density and the pressure based on absorption spectroscopy, by sweeping the absorption line and fittingthe experiment data with a Lorentzian profile to obtainboth parameters. Due to Doppler broadening and pressure broadening, which is mainly dominated by the temperature of the cell and the pressure of buffer gas respectively, this work demonstrates a simulation of the errorbetween the peaks of the Lorentzian profile and the Voigt profile caused by bothfactors. The results indicates that the Doppler broadening contribution is insignificant with an error less than 0.015% at 313-513 K for a 4He density of 2 amg, and an error of 0.1% in the presence of 0.6-5 amg at 393 K. We conclude that the Doppler broadening could be ignored under above conditions, and that the Lorentzianprofile is suitably applied to fit the absorption spectrumobtainingboth parameters simultaneously. In addition we discuss the resolution and the instability due to thelight source, wavelength and the temperature of the cell. We find that the cell temperature, whose uncertainty is two orders of magnitude larger than the instability of the light source and the wavelength, is one of the main factors which contributes to the error.

  13. Spark Plasma Sintering and Upsetting of a Gas-Atomized/Air-Atomized Al Alloy Powder Mixture

    Science.gov (United States)

    Tünçay, Mehmet Masum; Muñiz-Lerma, José Alberto; Bishop, Donald Paul; Brochu, Mathieu

    2017-10-01

    Al-Zn-Mg-Cu alloy powder, Alumix 431D, was modified by replacing the native air-atomized pure Al particles with gas-atomized pure Al. Samples were sintered using spark plasma sintering (SPS), and upset forging was applied to the sintered samples by SPS. Densities over 98 and 99% of theoretical were obtained for the sintered and forged samples, respectively. Microstructural analysis and characterization of all samples were done using energy-dispersive spectroscopy and x-ray diffraction. Mechanical properties were evaluated using microhardness and flexural strength and strain measurements. The microhardness value of the T6 tempered sample was comparable to that of its wrought counterpart AA7075. Particle bonding after sintering was incomplete and reveals that composite oxide layer of Al-Zn-Mg-Cu alloy powder is difficult to disrupt, and it is necessary to apply a secondary process like forging to improve particle bonding. The loss in ductility following T6 tempering is ascribed to void formation due to the dissolution of the secondary phases, remaining undissolved precipitates, and a localized lack of cohesion between particles.

  14. Relationship between hydrogen gas and butanol production by Clostridium saccharoperbutylacetonicum

    Energy Technology Data Exchange (ETDEWEB)

    Brosseau, J.D.; Yan, J.Y.; Lo, K.V.

    1986-03-01

    Two simultaneous fermentations were performed at 26 degrees C with simultaneous inocula using Clostridium saccharoperbutylacetonicum. Fermentation 1 prevented the gas formed by the biomass from escaping the fermentor while 2 allowed the gas formed to escape. Fermentor 1 provided for the production of butanol, acetone, and ethanol, while when the H/sub 2/ formed was allowed to escape with fermentor 2, neither butanol nor acetone were produced. Ethanol was also formed in both fermentors and began along with the initial growth of biomass and continued until the fermentations were complete. Butanol and acetone production began after biomass growth had reached a maximum and began to subside. The butanol-acetone-ethanol millimolar yields and ratios were 38:1:14 respectively. The fermentor 2 results show that a yield of 2.1 l H/sub 2/, 93 or 370 mmol H/sub 2//mol glucose, was formed only during the growing stage of growth; neither butanol nor acetone were produced; ethanol was formed throughout the fermentation, reaching a yield of 15.2 mmolar. It appears that hydrogen gas is required for butanol production during the resting stage of growth. 16 references.

  15. Relativistic spectrum of hydrogen atom in the space-time non-commutativity

    Energy Technology Data Exchange (ETDEWEB)

    Moumni, Mustafa; BenSlama, Achour; Zaim, Slimane [Matter Sciences Department, Faculty of SE and SNV, University of Biskra (Algeria); Laboratoire de Physique Mathematique et Subatomique, Mentouri University, Constantine (Algeria); Matter Sciences Department, Faculty of Sciences, University of Batna (Algeria)

    2012-06-27

    We study space-time non-commutativity applied to the hydrogen atom and its phenomenological effects. We find that it modifies the Coulomb potential in the Hamiltonian and add an r{sup -3} part. By calculating the energies from Dirac equation using perturbation theory, we study the modifications to the hydrogen spectrum. We find that it removes the degeneracy with respect to the total angular momentum quantum number and acts like a Lamb shift. Comparing the results with experimental values from spectroscopy, we get a new bound for the space-time non-commutative parameter.

  16. Hyperbaric oxygen therapy for systemic gas embolism after hydrogen peroxide ingestion.

    Science.gov (United States)

    Byrne, Brendan; Sherwin, Robert; Courage, Cheryl; Baylor, Alfred; Dolcourt, Bram; Brudzewski, Jacek R; Mosteller, Jeffrey; Wilson, Robert F

    2014-02-01

    Hydrogen peroxide is a commonly available product and its ingestion has been demonstrated to produce in vivo gas bubbles, which can embolize to devastating effect. We report two cases of hydrogen peroxide ingestion with resultant gas embolization, one to the portal system and one cerebral embolus, which were successfully treated with hyperbaric oxygen therapy (HBO), and review the literature. Two individuals presented to our center after unintentional ingestion of concentrated hydrogen peroxide solutions. Symptoms were consistent with portal gas emboli (Patient A) and cerebral gas emboli (Patient B), which were demonstrated on imaging. They were successfully treated with HBO and recovered without event. As demonstrated by both our experience as well as the current literature, HBO has been used to successfully treat gas emboli associated with hydrogen peroxide ingestion. We recommend consideration of HBO in any cases of significant hydrogen peroxide ingestion with a clinical picture compatible with gas emboli. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Dynamics of a Rydberg hydrogen atom near a metal surface in the electron-extraction scheme

    Energy Technology Data Exchange (ETDEWEB)

    Iñarrea, Manuel [Área de Física Aplicada, Universidad de La Rioja, Logroño (Spain); Lanchares, Víctor [Departamento de Matemáticas y Computación, Universidad de La Rioja, Logroño, La Rioja (Spain); Palacián, Jesús [Departamento de Ingeniería Matemática e Informática, Universidad Pública de Navarra, Pamplona (Spain); Pascual, Ana I. [Departamento de Matemáticas y Computación, Universidad de La Rioja, Logroño, La Rioja (Spain); Salas, J. Pablo, E-mail: josepablo.salas@unirioja.es [Área de Física Aplicada, Universidad de La Rioja, Logroño (Spain); Yanguas, Patricia [Departamento de Ingeniería Matemática e Informática, Universidad Pública de Navarra, Pamplona (Spain)

    2015-01-23

    We study the classical dynamics of a Rydberg hydrogen atom near a metal surface in the presence of a constant electric field in the electron-extraction situation [1], e.g., when the field attracts the electron to the vacuum. From a dynamical point of view, this field configuration provides a dynamics richer than in the usual ion-extraction scheme, because, depending on the values of field and the atom–surface distance, the atom can be ionized only towards the metal surface, only to the vacuum or to the both sides. The evolution of the phase space structure as a function of the atom–surface distance is explored in the bound regime of the atom. In the high energy regime, the ionization mechanism is also investigated. We find that the classical results of this work are in good agreement with the results obtained in the wave-packet propagation study carried out by So et al. [1]. - Highlights: • We study a classical hydrogen atom near a metal surface plus a electric field. • We explore the phase space structure as a function of the field strength. • We find most of the electronic orbits are oriented along the field direction. • We study the ionization of the atom for several atom–surface distances. • This classical study is in good agreement with the quantum results.

  18. An Atomistic Tomographic Study of Oxygen and Hydrogen Atoms and their Molecules in CVD Grown Graphene.

    Science.gov (United States)

    Baik, Sung-Il; Ma, Lulu; Kim, Yoon-Jun; Li, Bo; Liu, Mingjie; Isheim, Dieter; Yakobson, Boris I; Ajayan, Pulickel M; Seidman, David N

    2015-11-25

    The properties and growth processes of graphene are greatly influenced by the elemental distributions of impurity atoms and their functional groups within or on the hexagonal carbon lattice. Oxygen and hydrogen atoms and their functional molecules (OH, CO, and CO2 ) positions' and chemical identities are tomographically mapped in three dimensions in a graphene monolayer film grown on a copper substrate, at the atomic part-per-million (atomic ppm) detection level, employing laser assisted atom-probe tomography. The atomistic plan and cross-sectional views of graphene indicate that oxygen, hydrogen, and their co-functionalities, OH, CO, and CO2 , which are locally clustered under or within the graphene lattice. The experimental 3D atomistic portrait of the chemistry is combined with computational density-functional theory (DFT) calculations to enhance the understanding of the surface state of graphene, the positions of the chemical functional groups, their interactions with the underlying Cu substrate, and their influences on the growth of graphene. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. A first-principle study on adsorption of atomic hydrogen on the two-dimensional hexagonal boron nitride monolayer

    Science.gov (United States)

    Hao, Ruirui; Shi, Jianzhang; Zhu, Lin; Ji, Linan; Sun, Tianye; Feng, Shujian

    2017-11-01

    The hydrogenation of the two-dimensional hexagonal boron nitride (H: h-BN) monolayer and electronic properties of hydride are studied in details based on dispersion-corrected density function theory (DFT-D). Particular attention has been fixed on the most favorable site, and on aggregation states, as well as the migration barrier for a hydrogen atom hopping on the 2D h-BN surface. In general, chemisorbed hydrogen atoms on the top of boron will stretch the Bsbnd N bonds nearby, but never break them. The migration of a hydrogen atom on the h-BN surface is prefer to be over the honeycomb sites, but it becomes difficult with the increase of adsorbed hydrogen atoms. Furthermore, adsorbed multiple hydrogen atoms are likely to move close to each other, and to form a hydrogen domain. Hence the 2D h-BN monolayers possesses stable and high-density hydrogen storage properties with single side. In additions, a process of hydrogenation is presented.

  20. On the treatment of ℓ-changing proton-hydrogen Rydberg atom collisions

    Science.gov (United States)

    Vrinceanu, D.; Onofrio, R.; Sadeghpour, H. R.

    2017-11-01

    Energy-conserving, angular momentum changing collisions between protons and highly excited Rydberg hydrogen atoms are important for precise understanding of atomic recombination at the photon decoupling era and the elemental abundance after primordial nucleosynthesis. Early approaches to ℓ-changing collisions used perturbation theory only for dipole-allowed (Δℓ = ±1) transitions. An exact non-perturbative quantum mechanical treatment is possible, but it comes at a computational cost for highly excited Rydberg states. In this paper, we show how to obtain a semiclassical limit that is accurate and simple, and develop further physical insights afforded by the non-perturbative quantum mechanical treatment.

  1. Survival of metastable hydrogen atoms passing through crossed electric and magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Robert, J.; Miniatura, C.; Perales, F.; Vassilev, G.; Reinhardt, J.; Baudon, J. (Paris-13 Univ., 93 - Villetaneuse (FR)); Bocvarski, V. (Belgrade Univ. (YU) Inst. Za Fiziku); Lorent, V. (Louvain Univ., Louvain-La-Neuve (BE). Inst. de Physique)

    1989-08-01

    In the present experiment, the motional electric field responsible for the quenching (and polarization) of metastable hydrogen atoms passing through a magnetic field, is compensated, for a prescribed atomic velocity, by a static electric field. The resulting continuous velocity selection has been tested over a wide range of velocities ((5/40) km/s). The relative velocity dispersion ranges from 5% at 40 km/s, to 22% at 5 km/s. As is confirmed by a calculation, the resolution is mainly determined by the quality of the matching of the two field profiles.

  2. Palladium-Catalyzed Atom-Transfer Radical Cyclization at Remote Unactivated C(sp3)-H Sites: Hydrogen-Atom Transfer of Hybrid Vinyl Palladium Radical Intermediates.

    Science.gov (United States)

    Ratushnyy, Maxim; Parasram, Marvin; Wang, Yang; Gevorgyan, Vladimir

    2018-03-01

    A novel mild, visible-light-induced palladium-catalyzed hydrogen atom translocation/atom-transfer radical cyclization (HAT/ATRC) cascade has been developed. This protocol involves a 1,5-HAT process of previously unknown hybrid vinyl palladium radical intermediates, thus leading to iodomethyl carbo- and heterocyclic structures. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Cerebral arterial gas embolism, ingestion of hydrogen peroxide and flight.

    Science.gov (United States)

    Joob, Beuy; Wiwanitkit, Viroj

    2017-03-01

    We read with interest the recent report by Smedley et al. on an interesting case of cerebral arterial gas embolism (CAGE) after pre-flight ingestion of hydrogen peroxide (H₂O₂). The authors discuss the safety of aero-medical transfer following H₂O₂ ingestion. We agree with the possible problems but the concern on the other side of the coin needs to be mentioned; can transfer be delayed is the big question? Indeed, as reported by others, ingestion of even a small amount of concentrated H₂O₂ can result in CAGE. Hence, whether aero-medical transfer proceeds or not, severe, life-threatening embolism can occur. Since it was reported that "complete neurologic recovery occurred quickly with hyperbaric therapy", this supports the contention that the fastest transfer of the patient for hyperbaric treatment should be the primary focus.

  4. A mathematical framework for modelling and evaluating natural gas pipeline networks under hydrogen injection

    Energy Technology Data Exchange (ETDEWEB)

    Tabkhi, F.; Azzaro-Pantel, C.; Pibouleau, L.; Domenech, S. [Laboratoire de Genie Chimique, UMR5503 CNRS/INP/UPS, 5 rue Paulin Talabot F-BP1301, 31106 Toulouse Cedex 1 (France)

    2008-11-15

    This article presents the framework of a mathematical formulation for modelling and evaluating natural gas pipeline networks under hydrogen injection. The model development is based on gas transport through pipelines and compressors which compensate for the pressure drops by implying mainly the mass and energy balances on the basic elements of the network. The model was initially implemented for natural gas transport and the principle of extension for hydrogen-natural gas mixtures is presented. The objective is the treatment of the classical fuel minimizing problem in compressor stations. The optimization procedure has been formulated by means of a nonlinear technique within the General Algebraic Modelling System (GAMS) environment. This work deals with the adaptation of the current transmission networks of natural gas to the transport of hydrogen-natural gas mixtures. More precisely, the quantitative amount of hydrogen that can be added to natural gas can be determined. The studied pipeline network, initially proposed in [1] is revisited here for the case of hydrogen-natural gas mixtures. Typical quantitative results are presented, showing that the addition of hydrogen to natural gas decreases significantly the transmitted power: the maximum fraction of hydrogen that can be added to natural gas is around 6 mass% for this example. (author)

  5. Entropy of Relativistic Mono-Atomic Gas and Temperature Relativistic Transformation in Thermodynamics

    Directory of Open Access Journals (Sweden)

    Edward Bormashenko

    2007-09-01

    Full Text Available It is demonstrated that the entropy of the ideal mono-atomic gas comprisingidentical spherical atoms is not conserved under the Planck-Einstein like relativistictemperature transformation, as a result of the change in the number of atomic degrees offreedom. This fact supports the idea that there is no universal relativistic temperaturetransformation.

  6. Microsensor measurements of hydrogen gas dynamics in cyanobacterial microbial mats.

    Science.gov (United States)

    Nielsen, Michael; Revsbech, Niels P; Kühl, Michael

    2015-01-01

    We used a novel amperometric microsensor for measuring hydrogen gas production and consumption at high spatio-temporal resolution in cyanobacterial biofilms and mats dominated by non-heterocystous filamentous cyanobacteria (Microcoleus chtonoplastes and Oscillatoria sp.). The new microsensor is based on the use of an organic electrolyte and a stable internal reference system and can be equipped with a chemical sulfide trap in the measuring tip; it exhibits very stable and sulfide-insensitive measuring signals and a high sensitivity (1.5-5 pA per μmol L(-1) H2). Hydrogen gas measurements were done in combination with microsensor measurements of scalar irradiance, O2, pH, and H2S and showed a pronounced H2 accumulation (of up to 8-10% H2 saturation) within the upper mm of cyanobacterial mats after onset of darkness and O2 depletion. The peak concentration of H2 increased with the irradiance level prior to darkening. After an initial build-up over the first 1-2 h in darkness, H2 was depleted over several hours due to efflux to the overlaying water, and due to biogeochemical processes in the uppermost oxic layers and the anoxic layers of the mats. Depletion could be prevented by addition of molybdate pointing to sulfate reduction as a major sink for H2. Immediately after onset of illumination, a short burst of presumably photo-produced H2 due to direct biophotolysis was observed in the illuminated but anoxic mat layers. As soon as O2 from photosynthesis started to accumulate, the H2 was consumed rapidly and production ceased. Our data give detailed insights into the microscale distribution and dynamics of H2 in cyanobacterial biofilms and mats, and further support that cyanobacterial H2 production can play a significant role in fueling anaerobic processes like e.g., sulfate reduction or anoxygenic photosynthesis in microbial mats.

  7. Microsensor Measurements of Hydrogen Gas Dynamics in Cyanobacterial Microbial Mats

    Directory of Open Access Journals (Sweden)

    Michael eNielsen

    2015-07-01

    Full Text Available We used a novel amperometric microsensor for measuring hydrogen gas production and consumption at high spatio-temporal resolution in cyanobacterial biofilms and mats dominated by non-heterocystous filamentous cyanobacteria (Microcoleus chtonoplastes and Oscillatoria spp.. The new microsensor is based on the use of an organic electrolyte and a stable internal reference system and can be equipped with a chemical sulfide trap in the measuring tip; it exhibits very stable and sulfide-insensitive measuring signals and a high sensitivity (1.5-5 pA per µmol L-1 H2. Hydrogen gas measurements were done in combination with microsensor measurements of scalar irradiance, O2, pH, and H2S and showed a pronounced H2 accumulation (of up to 8-10% H2 saturation within the upper mm of cyanobacterial mats after onset of darkness and O2 depletion. The peak concentration of H2 increased with the irradiance level prior to darkening. After an initial build-up over the first 1-2 hours in darkness, H2 was depleted over several hours due to efflux to the overlaying water, and due to biogeochemical processes in the uppermost oxic layers and the anoxic layers of the mats. Depletion could be prevented by addition of molybdate pointing to sulfate reduction as a major sink for H2. Immediately after onset of illumination, a short burst of presumably photo-produced H2 due to direct photobiolysis was observed in the illuminated but anoxic mat layers. As soon as O2 from photosynthesis started to accumulate, the H2 was consumed rapidly and production ceased. Our data give detailed insights into the microscale distribution and dynamics of H2 in cyanobacterial biofilms and mats, and further support that cyanobacterial H2 production can play a significant role in fueling anaerobic processes like e.g. sulfate reduction or anoxygenic photosynthesis in microbial mats.

  8. Interstitial modification of palladium nanoparticles with boron atoms as a green catalyst for selective hydrogenation

    Science.gov (United States)

    Chan, Chun Wong Aaron; Mahadi, Abdul Hanif; Li, Molly Meng-Jung; Corbos, Elena Cristina; Tang, Chiu; Jones, Glenn; Kuo, Winson Chun Hsin; Cookson, James; Brown, Christopher Michael; Bishop, Peter Trenton; Tsang, Shik Chi Edman

    2014-12-01

    Lindlar catalysts comprising of palladium/calcium carbonate modified with lead acetate and quinoline are widely employed industrially for the partial hydrogenation of alkynes. However, their use is restricted, particularly for food, cosmetic and drug manufacture, due to the extremely toxic nature of lead, and the risk of its leaching from catalyst surface. In addition, the catalysts also exhibit poor selectivities in a number of cases. Here we report that a non-surface modification of palladium gives rise to the formation of an ultra-selective nanocatalyst. Boron atoms are found to take residence in palladium interstitial lattice sites with good chemical and thermal stability. This is favoured due to a strong host-guest electronic interaction when supported palladium nanoparticles are treated with a borane tetrahydrofuran solution. The adsorptive properties of palladium are modified by the subsurface boron atoms and display ultra-selectivity in a number of challenging alkyne hydrogenation reactions, which outclass the performance of Lindlar catalysts.

  9. Optical potential studies on positron scattering by hydrogenic-type atoms

    Energy Technology Data Exchange (ETDEWEB)

    Ratnavelu, Kuru E-mail: kuru@mail.nhu.ou.edu; Kamali, M.Z.M.; Ng, S.Y

    2002-05-01

    In this report, we will present the work that has been done using the coupled-channels-optical method for positron scattering by atomic hydrogen and atomic lithium at low intermediate energies. The method allows the simultaneous treatment of the target channels and the Positronium (Ps) channels in the close-coupling method and the incorporation of the continuum effects via an optical potential method. Our latest calculations using the CCO(6,3) for positron-hydrogen system for energies ranging from 13.8 to 40 eV will be presented. For the positron-lithium system, we will report our initial findings for energies ranging from 6 to 20 eV using the CCO(2,3) model. Ionization, Ps formation, total cross-sections and differential cross-sections are presented.

  10. A tabulation of the bound-state energies of atomic hydrogen

    CERN Document Server

    Horbatsch, M

    2016-01-01

    We present tables for the bound-state energies for atomic hydrogen. The tabulated energies include the hyperfine structure, and thus this work extends the work of Rev. Mod. Phys. {\\bf 84}, 1527 (2012), which excludes hyperfine structure. The tabulation includes corrections of the hyperfine structure due to the anomalous moment of the electron, due to the finite mass of the proton, and due to off-diagonal matrix elements of the hyperfine Hamiltonian. These corrections are treated incorrectly in most other works. Simple formulas valid for all quantum numbers are presented for the hyperfine corrections. The tabulated energies have uncertainties of less than 1 kHz for all states. This accuracy is possible because of the recent precision measurement [Nature, {\\bf 466}, 213 (2010); Science, {\\bf 339}, 417] of the proton radius. The effect of this new radius on the energy levels is also tabulated, and the energies are compared to precision measurements of atomic hydrogen energy intervals.

  11. The reaction of hydrogen atoms with hydrogen peroxide as a function of temperature

    DEFF Research Database (Denmark)

    Lundström, T.; Christensen, H.; Sehested, K.

    2001-01-01

    The temperature dependence for the reaction of H atoms with H2O2 at pH 1 has been determined using pulse radiolysis technique. The reaction was studied in the temperature range 10-120 degreesC. The rate constant at 25 degreesC was found to be 5.1 +/- 0.5 x 10(7) dm(3) mol(-1) s(-1) and the activa...

  12. a Study of Using Hydrogen Gas for Steam Boiler in CHOLOR- Alkali Manufacturing

    Science.gov (United States)

    Peantong, Sasitorn; Tangjitsitcharoen, Somkiat

    2017-06-01

    Main products of manufacturing of Cholor - Alkali, which commonly known as industrial chemical, are chlorine gas (Cl2), Sodium Hydroxide (NaOH) and hydrogen gas (H2). Chorine gas and sodium hydroxide are two main products for commercial profit; where hydrogen gas is by product. Most industries release hydrogen gas to atmosphere as it is non-profitable and less commercial scale. This study aims to make the most use of hydrogen as a substitute energy of natural gas for steam boiler to save energy cost. The second target of this study is to reduce level of CO2 release to air as a consequence of boiler combustion. This study suggests to install boiler that bases on hydrogen as main power with a high turndown ratio of at least 1:6. However, this case study uses boiler with two mode such as natural gas (NG) mode and mixed mode as they need to be flexible for production. Never the less, the best boiler selection is to use single mode energy of hydrogen. The most concerned issue about hydrogen gas is explosion during combustion stage. Stabilization measures at emergency stop is introduced to control H2 pressure to protect the explosion. This study varies ratio of natural gas to hydrogen gas to find the optimal level of two energy sources for boiler and measure total consumption through costing model; where CO2 level is measured at the boiler stack. The result of this study shows that hydrogen gas can be a substitute energy with natural gas and can reduce cost. Natural gas cost saving is 248,846 baht per month and reduce level of NOx is 80 ppm 7% O2 and 2 % of CO2 release to air as a consequence of boiler combustion.

  13. Direct time-resolved spectroscopic investigation of intramolecular hydrogen atom transfer of deoxyblebbistatin

    Science.gov (United States)

    Li, Ming-De; Zhu, Ruixue; Lee Phillips, David

    2017-09-01

    The photophysics and photochemistry of deoxyblebbistatin was investigated using femtosecond time-resolved transient absorption spectroscopy. An ultrafast intramolecular hydrogen atom transfer (IHAT) appears to take place via the first singlet excited state of deoxyblebbistatin within 8 ps. Absorption and fluorescence photochemical results indicate the IHAT process leads to mainly conversion of deoxyblebbistatin into an enol form final product which was observed and characterized by resonance Raman spectroscopy.

  14. Precision measurement of the 1S-2S transition in atomic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Parthey, Christian G.; Matveev, Arthur; Alnis, Janis; Beyer, Axel; Kolachevsky, Nikolai; Pohl, Randolf; Udem, Thomas [Max-Planck-Institut fuer Quantenoptik, 85748 Garching (Germany); Haensch, Theodor W. [Max-Planck-Institut fuer Quantenoptik, 85748 Garching (Germany); Ludwig-Maximilians-Universitaet, 80799 Muenchen (Germany)

    2011-07-01

    Precision spectroscopy of the 1S-2S transition in atomic hydrogen has been used to test quantum electrodynamics (QED), determine the Rydberg constant and the proton charge radius. It can also be used to set limits on possible Lorentz-boost invariance violations. Here we report on a new measurement of the 1S-2S transition pushing the uncertainty to the 10{sup -15} level.

  15. Atomic Hydrogen Properties of AGN Host Galaxies: HI in 16 NUclei of GAlaxies (NUGA) Sources

    OpenAIRE

    S. de Haan; Schinnerer, E.; Mundell, C. G.; Garcia-Burillo, S.; Combes, F.

    2007-01-01

    We present a comprehensive spectroscopic imaging survey of the distribution and kinematics of atomic hydrogen (HI) in 16 nearby spiral galaxies hosting low luminosity AGN, observed with high spectral and spatial resolution (resolution: ~20 arcsec, 5 km/s) using the NRAO Very Large Array (VLA). The sample contains a range of nuclear types, ranging from Seyfert to star-forming nuclei and was originally selected for the NUclei of GAlaxies project (NUGA) - a spectrally and spatially resolved inte...

  16. Chemical structure of descriptors with an active hydrogen atom in certain bioregulators.

    Science.gov (United States)

    Kurchii, B A

    1996-01-01

    The chemical structure of descriptors (D) for some plant growth regulators (PGR), herbicides, pesticides and drugs is described. The presence of an active hydrogen atom in molecules is an essential factor determining biological activity of chemicals. The results obtained from the study of dependence existing between the structure of a certain substance and its biological activity may be used in designing of novel compounds which possess in biological activity.

  17. Regularity and Chaos in the Hydrogen Atom Highly Excited with a Strong Magnetic Field

    Directory of Open Access Journals (Sweden)

    M. Amdouni

    2014-01-01

    Full Text Available The effects of the relativistic corrections on the energy spectra are analyzed. Effective simulations based on manipulations of operators in the Sturmian basis are developed. Discrete and continuous energy spectra of a hydrogen atom with realistic nucleus mass in a strong magnetic field are computed. The transition from regularity to chaos in diamagnetic problem with the effect of the nucleus recoil energy is explored. Anticrossing of energy levels is observed for strong magnetic field.

  18. Proton and hydrogen atom detection efficiency of resistance strip magnetic electron multiplier particle-counting system

    Energy Technology Data Exchange (ETDEWEB)

    Wehrenberg, P.J.; Clark, K.C.

    1976-10-01

    The absolute detection efficiency for protons and for hydrogen atoms in the energy range 5--60 keV is determined for a resistance strip magnetic electron multiplier particle-counting system. Significant history-dependent gain variations are discussed. The detector system is suitable for use in coincidence experiments requiring particle-counting rates to 1.0 MHz and timing accuracies of 3.0 nsec. (AIP)

  19. Thresholds to Chaos and Ionization for the Hydrogen Atom in Rotating Fields

    OpenAIRE

    Chandre, C.; Farrelly, David; Uzer, T.

    2002-01-01

    We analyze the classical phase space of the hydrogen atom in crossed magnetic and circularly polarized microwave fields in the high frequency regime, using the Chirikov resonance overlap criterion and the renormalization map. These methods are used to compute thresholds to large scale chaos and to ionization. The effect of the magnetic field is a strong stabilization of a set of invariant tori which bound the trajectories and prevent stochastic ionization. In order to ionize, larger amplitude...

  20. Reactions of atomic hydrogen with formic acid and carbon monoxide in solid parahydrogen I: Anomalous effect of temperature.

    Science.gov (United States)

    Paulson, Leif O; Mutunga, Fredrick M; Follett, Shelby E; Anderson, David T

    2014-09-11

    Low-temperature condensed phase reactions of atomic hydrogen with closed-shell molecules have been studied in rare gas matrices as a way to generate unstable chemical intermediates and to study tunneling-driven chemistry. Although parahydrogen (pH2) matrix isolation spectroscopy allows these reactions to be studied equally well, little is known about the analogous reactions conducted in a pH2 matrix host. In this study, we present Fourier transform infrared (FTIR) spectroscopic studies of the 193 nm photoinduced chemistry of formic acid (HCOOH) isolated in a pH2 matrix over the 1.7 to 4.3 K temperature range. Upon short-term irradiation the HCOOH readily undergoes photolysis to yield CO, CO2, HOCO, HCO and H atoms. Furthermore, after photolysis at 1.9 K tunneling reactions between migrating H atoms and trapped HCOOH and CO continue to produce HOCO and HCO, respectively. A series of postphotolysis kinetic experiments at 1.9 K with varying photolysis conditions and initial HCOOH concentrations show the growth of HOCO consistently follows single exponential (k = 4.9(7)x10(-3) min(-1)) growth kinetics. The HCO growth kinetics is more complex displaying single exponential growth under certain conditions, but also biexponential growth at elevated CO concentrations and longer photolysis exposures. By varying the temperature after photolysis, we show the H atom reaction kinetics qualitatively change at ∼2.7 K; the reaction that produces HOCO stops at higher temperatures and is only observed at low temperature. We rationalize these results using a kinetic mechanism that involves formation of an H···HCOOH prereactive complex. This study clearly identifies anomalous temperature effects in the reaction kinetics of H atoms with HCOOH and CO in solid pH2 that deserve further study and await full quantitative theoretical modeling.

  1. Hydrodesulphurization of Light Gas Oil using hydrogen from the Water Gas Shift Reaction

    Science.gov (United States)

    Alghamdi, Abdulaziz

    2009-12-01

    The production of clean fuel faces the challenges of high production cost and complying with stricter environmental regulations. In this research, the ability of using a novel technology of upgrading heavy oil to treat Light Gas Oil (LGO) will be investigated. The target of this project is to produce cleaner transportation fuel with much lower cost of production. Recently, a novel process for upgrading of heavy oil has been developed at University of Waterloo. It is combining the two essential processes in bitumen upgrading; emulsion breaking and hydroprocessing into one process. The water in the emulsion is used to generate in situ hydrogen from the Water Gas Shift Reaction (WGSR). This hydrogen can be used for the hydrogenation and hydrotreating reaction which includes sulfur removal instead of the expensive molecular hydrogen. This process can be carried out for the upgrading of the bitumen emulsion which would improve its quality. In this study, the hydrodesulphurization (HDS) of LGO was conducted using in situ hydrogen produced via the Water Gas Shift Reaction (WGSR). The main objective of this experimental study is to evaluate the possibility of producing clean LGO over dispersed molybdenum sulphide catalyst and to evaluate the effect of different promoters and syn-gas on the activity of the dispersed Mo catalyst. Experiments were carried out in a 300 ml Autoclave batch reactor under 600 psi (initially) at 391°C for 1 to 3 hours and different amounts of water. After the hydrotreating reaction, the gas samples were collected and the conversion of carbon monoxide to hydrogen via WGSR was determined using a refinery gas analyzer. The sulphur content in liquid sample was analyzed via X-Ray Fluorescence. Experimental results showed that using more water will enhance WGSR but at the same time inhibits the HDS reaction. It was also shown that the amount of sulfur removed depends on the reaction time. The plan is to investigate the effect of synthesis gas (syngas

  2. Chemisorption of hydrogen atoms and hydroxyl groups on stretched graphene: A coupled QM/QM study

    Science.gov (United States)

    Katin, Konstantin P.; Prudkovskiy, Vladimir S.; Maslov, Mikhail M.

    2017-09-01

    Using the density functional theory coupled with the nonorthogonal tight-binding model, we analyze the chemisorption of hydrogen atoms and hydroxyl groups on the unstrained and stretched graphene sheets. Drawback of finite cluster model of graphene for the chemisorption energy calculation in comparison with the QM/QM approach applied is discussed. It is shown that the chemisorption energy for the hydroxyl group is sufficiently lower than for hydrogen at stretching up to 7.5%. The simultaneous paired chemisorption of hydrogen and hydroxyl groups on the same hexagon has also been examined. Adsorption of two radicals in ortho and para positions is found to be more energetically favorable than those in meta position at any stretching considered. In addition the energy difference between adsorbent pairs in ortho and para positions decreases as the stretching rises. It could be concluded that the graphene stretching leads to the loss of preferred mutual arrangement of two radicals on its surface.

  3. THE INFRARED SPECTRA OF POLYCYCLIC AROMATIC HYDROCARBONS WITH SOME OR ALL HYDROGEN ATOMS REMOVED

    Energy Technology Data Exchange (ETDEWEB)

    Bauschlicher, Charles W. Jr. [Entry Systems and Technology Division, Mail Stop 230-3, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Ricca, Alessandra, E-mail: Charles.W.Bauschlicher@nasa.gov, E-mail: Alessandra.Ricca-1@nasa.gov [Carl Sagan Center, SETI Institute, 189 Bernardo Avenue, Mountain View, CA 94043 (United States)

    2013-10-20

    The loss of one hydrogen from C{sub 96}H{sub 24} does not significantly affect the infrared spectra of the neutral, cation, or anion. Excluding a very weak C-C stretching band at 5.1 μm, the loss of two adjacent duo hydrogens does not significantly affect the spectra compared with the parent. Removing all of the hydrogen atoms significantly increases the intensity of the new C-C stretching band, and, for the cation, shifts it to a longer (5.2 μm) wavelength. Observations show a feature near 5.25 μm, which has been attributed to overtone and combination bands from polycyclic aromatic hydrocarbons (PAHs). This current work suggests that dehydrogenated PAHs might also contribute to this band, but its weakness implies that fully dehydrogenated cationic or dicationic species are very rare.

  4. On the combination of a low energy hydrogen atom beam with a cold multipole ion trap

    Energy Technology Data Exchange (ETDEWEB)

    Borodi, Gheorghe

    2008-12-09

    The first part of the activities of this thesis was to develop a sophisticated ion storage apparatus dedicated to study chemical processes with atomic hydrogen. The integration of a differentially pumped radical beam source into an existing temperature variable 22- pole trapping machine has required major modifications. Since astrophysical questions have been in the center of our interest, the introduction first gives a short overview of astrophysics and -chemistry. The basics of ion trapping in temperature variable rf traps is well-documented in the literature; therefore, the description of the basic instrument (Chapter 2) is kept rather short. Much effort has been put into the development of an intense and stable source for hydrogen atoms the kinetic energy of which can be changed. Chapter 3 describes this module in detail with emphasis on the integration of magnetic hexapoles for guiding the atoms and special treatments of the surfaces for reducing H-H recombination. Due to the unique sensitivity of the rf ion trapping technique, this instrument allows one to study a variety of reactions of astrochemical and fundamental interest. The results of this work are summarized in Chapter 4. Reactions of CO{sub 2}{sup +} with hydrogen atoms and molecules have been established as calibration standard for in situ determination of H and H{sub 2} densities over the full temperature range of the apparatus (10 K-300 K). For the first time, reactions of H- and D-atoms with the ionic hydrocarbons CH{sup +}, CH{sub 2}{sup +}, and CH{sub 4}{sup +} have been studied at temperatures of interstellar space. A very interesting, not yet fully understood collision system is the interaction of protonated methane with H. The outlook presents some ideas, how to improve the new instrument and a few reaction systems are mentioned which may be studied next. (orig.)

  5. Muon transfer from muonic hydrogen to heavier atoms; Transfert de charge muonique

    Energy Technology Data Exchange (ETDEWEB)

    Dupays, A

    2004-06-01

    This work concerns muon transfer from muonic hydrogen to heavier atoms. Recently, a method of measurement of the hyperfine structure of ground-state muonic hydrogen based on the collision energy dependence of the muon transfer rate to oxygen has been proposed. This proposal is based on measurements which where performed at the Paul Scherrer Institute in the early nineties which indicate that the muon transfer from muonic hydrogen to oxygen increases by a factor of 4 going from thermal to 0.12 eV energies. The motivation of our calculations was to confirm this behaviour. To study the collision energy dependence of the muon transfer rate, we have used a time-independent close-coupling method. We have set up an hyperspherical elliptic formalism valid for nonzero total angular momentum which allows accurate computations of state-to-state reactive and charge exchange processes. We have applied this formalism to muon-transfer process to oxygen and neon. The comparison with experimental results is in both cases excellent. Finally, the neon transfer rate dependence with energy suggests to use neon instead of oxygen to perform a measurement of the hyperfine structure of muonic hydrogen. The results of accurate calculations of the muon transfer rates from muonic protium and deuterium atoms to nitrogen, oxygen and neon are also reported. Very good agreement with measured rates is obtained and for the three systems, the isotopic effect is perfectly reproduced. (author)

  6. Atomic configuration of hydrogenated and clean tantalum(111) surfaces: Bond relaxation, energy entrapment and electron polarization

    Science.gov (United States)

    Bo, Maolin; Li, Lei; Guo, Yongling; Yao, Chuang; Peng, Cheng; Sun, Chang Q.

    2018-01-01

    By studying the tantalum (Ta)(111) surface with X-ray photoemission spectroscopy and density functional theory, we determined binding energy values for the clean Ta(111) (+3.068 eV) and hydrogenated Ta(111) (+3.421 eV) surfaces with an isolated atom level of 18.977 eV. Using the bond-band barrier and zone-selective electron spectroscopy correlation, we investigated the mechanism of hydrogenation adsorption on the Ta(111) surface. We found the local densities of states of the first layer of Ta atoms in the reconstructed structure, which formed on the adsorbent hydrogen of the surface chemical bond contracts and dipole polarization. Moreover, we showed that on the Ta(111) surface, the hydrogen-induced surface core level shifts are dominated by quantum entrapment and are proportional to the calculated hybridized orbitals of the valence band. The latter is therefore correlated to the local surface chemical reactivity and is useful for other adsorbate systems on transition metals.

  7. Laboratory Studies of Hydrogen Gas Generation Using the Cobalt Chloride Catalyzed Sodium Borohydride-Water Reaction

    Science.gov (United States)

    2015-07-01

    reaction to generate hydrogen gas to inflate lighter-than-air vehicles . RESULTS When using CoCl2 as a catalyst, we discovered that distilled or...driving prices up. Consequently, the use of hydrogen gas to inflate LTA vehicles is gaining greater acceptance; many countries (military and commercial...due to leakage, safety, and size concerns. Hydrogen is less flammable than gasoline. In summary, the demand to use LTA vehicles for military and

  8. Analytical model of neutral gas shielding for hydrogen pellet ablation

    Energy Technology Data Exchange (ETDEWEB)

    Kuteev, Boris V.; Tsendin, Lev D. [State Technical Univ., St. Petersburg (Russian Federation)

    2001-11-01

    A kinetic gasdynamic scaling for hydrogen pellet ablation is obtained in terms of a neural gas shielding model using both numerical and analytical approaches. The scaling on plasma and pellet parameters proposed in the monoenergy approximation by Milora and Foster dR{sub pe}/dt{approx}S{sub n}{sup 2/3}R{sub p}{sup -2/3}q{sub eo}{sup 1/3}m{sub i}{sup -1/3} is confirmed. Here R{sub p} is the pellet radius, S{sub n} is the optical thickness of a cloud, q{sub eo} is the electron energy flux density and m{sub i} is the molecular mass. Only the numeral factor is approximately two times less than that for the monoenergy approach. Due to this effect, the pellet ablation rates, which were obtained by Kuteev on the basis of the Milora scaling, should be reduced by a factor of 1.7. Such a modification provides a reasonable agreement (even at high plasma parameters) between the two-dimensional kinetic model and the one-dimensional monoenergy approximation validated in contemporary tokamak experiments. As the could (in the kinetic approximation) is significantly thicker than that for the monoenergy case as well as the velocities of the gas flow are much slower, the relative effect of plasma and magnetic shielding on the ablation rate is strongly reduced. (author)

  9. Shock-wave proton acceleration from a hydrogen gas jet

    Science.gov (United States)

    Cook, Nathan; Pogorelsky, Igor; Polyanskiy, Mikhail; Babzien, Marcus; Tresca, Olivier; Maharjan, Chakra; Shkolnikov, Peter; Yakimenko, Vitaly

    2013-04-01

    Typical laser acceleration experiments probe the interaction of intense linearly-polarized solid state laser pulses with dense metal targets. This interaction generates strong electric fields via Transverse Normal Sheath Acceleration and can accelerate protons to high peak energies but with a large thermal spectrum. Recently, the advancement of high pressure amplified CO2 laser technology has allowed for the creation of intense (10^16 Wcm^2) pulses at λ˜10 μm. These pulses may interact with reproducible, high rep. rate gas jet targets and still produce plasmas of critical density (nc˜10^19 cm-3), leading to the transference of laser energy via radiation pressure. This acceleration mode has the advantage of producing narrow energy spectra while scaling well with pulse intensity. We observe the interaction of an intense CO2 laser pulse with an overdense hydrogen gas jet. Using two pulse optical probing in conjunction with interferometry, we are able to obtain density profiles of the plasma. Proton energy spectra are obtained using a magnetic spectrometer and scintillating screen.

  10. Gas-phase hydrogenation influence on defect behavior in titanium-based hydrogen-storage material

    OpenAIRE

    Laptev, Roman S.; Viktor N. Kudiiarov; Bordulev, Yuri S.; Mikhaylov, Andrey A.; Andrey M. Lider

    2017-01-01

    Titanium and its alloys are promising materials for hydrogen storage. However, hydrogen penetration accompanies the exploitation of hydrogen storage alloys. In particular, hydrogen penetration and accumulation in titanium alloys changes their mechanical properties. Therefore, the research works of such materials are mainly focused on improving the reversibility of hydrogen absorption-liberation processes, increasing the thermodynamic characteristics of the alloys, and augmenting their hydroge...

  11. Atom Probe Analysis of Ex Situ Gas-Charged Stable Hydrides.

    Science.gov (United States)

    Haley, Daniel; Bagot, Paul A J; Moody, Michael P

    2017-04-01

    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.

  12. High-multipole excitations of hydrogen-like atoms by twisted photons near a phase singularity

    Science.gov (United States)

    Afanasev, Andrei; Carlson, Carl E.; Mukherjee, Asmita

    2016-07-01

    We calculate transition amplitudes and cross sections for excitation of hydrogen-like atoms by the twisted photon states, or photon states with angular momentum projection on the direction of propagation exceeding ℏ. If the target atom is located at distances of the order of atomic size near the phase singularity in the vortex center, the transition rates into the states with orbital angular momentum {l}f\\gt 1 become comparable with the rates for electric dipole transitions. It is shown that when the transition rates are normalized to the local photon flux, the resulting cross sections for {l}f\\gt 1 are singular near the optical vortex center. The relation to the ‘quantum core’ concept introduced by Berry and Dennis is discussed.

  13. Atomic Layer Deposition of Ultrathin Nickel Sulfide Films and Preliminary Assessment of Their Performance as Hydrogen Evolution Catalysts.

    Science.gov (United States)

    Çimen, Yasemin; Peters, Aaron W; Avila, Jason R; Hoffeditz, William L; Goswami, Subhadip; Farha, Omar K; Hupp, Joseph T

    2016-11-22

    Transition metal sulfides show great promise for applications ranging from catalysis to electrocatalysis to photovoltaics due to their high stability and conductivity. Nickel sulfide, particularly known for its ability to electrochemically reduce protons to hydrogen gas nearly as efficiently as expensive noble metals, can be challenging to produce with certain surface site compositions or morphologies, e.g., conformal thin films. To this end, we employed atomic layer deposition (ALD), a preeminent method to fabricate uniform and conformal films, to construct thin films of nickel sulfide (NiSx) using bis(N,N'-di-tert-butylacetamidinato)nickel(II) (Ni(amd)2) vapor and hydrogen sulfide gas. Effects of experimental conditions such as pulse and purge times and temperature on the growth of NiSx were investigated. These revealed a wide temperature range, 125-225 °C, over which self-limiting NiSx growth can be observed. In situ quartz crystal microbalance (QCM) studies revealed conventional linear growth behavior for NiSx films, with a growth rate of 9.3 ng/cm2 per cycle being obtained. The ALD-synthesized films were characterized using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) methods. To assess the electrocatalyitic activity of NiSx for evolution of molecular hydrogen, films were grown on conductive-glass supports. Overpotentials at a current density of 10 mA/cm2 were recorded in both acidic and pH 7 phosphate buffer aqueous reaction media and found to be 440 and 576 mV, respectively, with very low NiSx loading. These results hint at the promise of ALD-grown NiSx materials as water-compatible electrocatalysts.

  14. Blending of hydrogen in natural gas distribution systems. Volume I. Gas blends flow in distribution system, mixing points, and regulatory standards. Final report, June 1, 1976--August 30, 1977. [10 and 20% hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    None

    1977-09-01

    This volume of the subject study ''Blending of Hydrogen in Natural Gas Distribution Systems'' describes studies on the determination of gas distribution system flows with hydrogen - natural gas blends, potential hydrogen admission points to gas distribution systems, and the impact of hydrogen - natural gas blends on regulatory standards for gas distribution systems. The studies resulted in the following principal findings: (1) Most existing natural gas distribution systems could adequately transport 20% blends of hydrogen by volume with little or no modification. (2) The best point of admission of the hydrogen into a natural gas distribution system would be at the meter and regulating stations supplying a particular distribution system. (3) The impact of hydrogen - natural gas blends on state regulatory standards appears to be minimal for PSE and G, but requires further study for various National Codes and for other states.

  15. Low cost hydrogen/novel membrane technology for hydrogen separation from synthesis gas. Task 1, Literature survey

    Energy Technology Data Exchange (ETDEWEB)

    1986-02-01

    To make the coal-to-hydrogen route economically attractive, improvements are being sought in each step of the process: coal gasification, water-carbon monoxide shift reaction, and hydrogen separation. This report addresses the use of membranes in the hydrogen separation step. The separation of hydrogen from synthesis gas is a major cost element in the manufacture of hydrogen from coal. Separation by membranes is an attractive, new, and still largely unexplored approach to the problem. Membrane processes are inherently simple and efficient and often have lower capital and operating costs than conventional processes. In this report current ad future trends in hydrogen production and use are first summarized. Methods of producing hydrogen from coal are then discussed, with particular emphasis on the Texaco entrained flow gasifier and on current methods of separating hydrogen from this gas stream. The potential for membrane separations in the process is then examined. In particular, the use of membranes for H{sub 2}/CO{sub 2}, H{sub 2}/CO, and H{sub 2}/N{sub 2} separations is discussed. 43 refs., 14 figs., 6 tabs.

  16. Surface atomic relaxation and magnetism on hydrogen-adsorbed Fe(110) surfaces from first principles

    Science.gov (United States)

    Chohan, Urslaan K.; Jimenez-Melero, Enrique; Koehler, Sven P. K.

    2016-11-01

    We have computed adsorption energies, vibrational frequencies, surface relaxation and buckling for hydrogen adsorbed on a body-centred-cubic Fe(110) surface as a function of the degree of H coverage. This adsorption system is important in a variety of technological processes such as the hydrogen embrittlement in ferritic steels, which motivated this work, and the Haber-Bosch process. We employed spin-polarised density functional theory to optimise geometries of a six-layer Fe slab, followed by frozen mode finite displacement phonon calculations to compute Fe-H vibrational frequencies. We have found that the quasi-threefold (3f) site is the most stable adsorption site, with adsorption energies of ∼3.0 eV/H for all coverages studied. The long-bridge (lb) site, which is close in energy to the 3f site, is actually a transition state leading to the stable 3f site. The calculated harmonic vibrational frequencies collectively span from 730 to 1220 cm-1, for a range of coverages. The increased first-to-second layer spacing in the presence of adsorbed hydrogen, and the pronounced buckling observed in the Fe surface layer, may facilitate the diffusion of hydrogen atoms into the bulk, and therefore impact the early stages of hydrogen embrittlement in steels.

  17. Precise calibration of few-cycle laser pulses with atomic hydrogen

    Science.gov (United States)

    Wallace, W. C.; Kielpinski, D.; Litvinyuk, I. V.; Sang, R. T.

    2017-12-01

    Interaction of atoms and molecules with strong electric fields is a fundamental process in many fields of research, particularly in the emerging field of attosecond science. Therefore, understanding the physics underpinning those interactions is of significant interest to the scientific community. One crucial step in this understanding is accurate knowledge of the few-cycle laser field driving the process. Atomic hydrogen (H), the simplest of all atomic species, plays a key role in benchmarking strong-field processes. Its wide-spread use as a testbed for theoretical calculations allows the comparison of approximate theoretical models against nearly-perfect numerical solutions of the three-dimensional time-dependent Schrödinger equation. Until recently, relatively little experimental data in atomic H was available for comparison to these models, and was due mostly due to the difficulty in the construction and use of atomic H sources. Here, we review our most recent experimental results from atomic H interaction with few-cycle laser pulses and how they have been used to calibrate important laser pulse parameters such as peak intensity and the carrier-envelope phase (CEP). Quantitative agreement between experimental data and theoretical predictions for atomic H has been obtained at the 10% uncertainty level, allowing for accurate laser calibration intensity at the 1% level. Using this calibration in atomic H, both accurate CEP data and an intensity calibration standard have been obtained Ar, Kr, and Xe; such gases are in common use for strong-field experiments. This calibration standard can be used by any laboratory using few-cycle pulses in the 1014 W cm‑2 intensity regime centered at 800 nm wavelength to accurately calibrate their peak laser intensity to within few-percent precision.

  18. Investigation of the Mechanism of Electron Capture and Electron Transfer Dissociation of Peptides with a Covalently Attached Free Radical Hydrogen Atom Scavenger.

    Science.gov (United States)

    Sohn, Chang Ho; Yin, Sheng; Peng, Ivory; Loo, Joseph A; Beauchamp, J L

    2015-11-15

    The mechanisms of electron capture and electron transfer dissociation (ECD and ETD) are investigated by covalently attaching a free-radical hydrogen atom scavenger to a peptide. The 2,2,6,6-tetramethylpiperidin-l-oxyl (TEMPO) radical was chosen as the scavenger due to its high hydrogen atom affinity (ca. 280 kJ/mol) and low electron affinity (ca. 0.45 ev), and was derivatized to the model peptide, FQX TEMPO EEQQQTEDELQDK. The X TEMPO residue represents a cysteinyl residue derivatized with an acetamido-TEMPO group. The acetamide group without TEMPO was also examined as a control. The gas phase proton affinity (882 kJ/mol) of TEMPO is similar to backbone amide carbonyls (889 kJ/mol), minimizing perturbation to internal solvation and sites of protonation of the derivatized peptides. Collision induced dissociation (CID) of the TEMPO tagged peptide dication generated stable odd-electron b and y type ions without indication of any TEMPO radical induced fragmentation initiated by hydrogen abstraction. The type and abundance of fragment ions observed in the CID spectra of the TEMPO and acetamide tagged peptides are very similar. However, ECD of the TEMPO labeled peptide dication yielded no backbone cleavage. We propose that a labile hydrogen atom in the charge reduced radical ions is scavenged by the TEMPO radical moiety, resulting in inhibition of N-C α backbone cleavage processes. Supplemental activation after electron attachment (ETcaD) and CID of the charge-reduced precursor ion generated by electron transfer of the TEMPO tagged peptide dication produced a series of b + H (b H ) and y + H (y H ) ions along with some c ions having suppressed intensities, consistent with stable O-H bond formation at the TEMPO group. In summary, the results indicate that ECD and ETD backbone cleavage processes are inhibited by scavenging of a labile hydrogen atom by the localized TEMPO radical moiety. This observation supports the conjecture that ECD and ETD processes involve long

  19. Hydrogen Embrittlement

    Science.gov (United States)

    Woods, Stephen; Lee, Jonathan A.

    2016-01-01

    Hydrogen embrittlement (HE) is a process resulting in a decrease in the fracture toughness or ductility of a metal due to the presence of atomic hydrogen. In addition to pure hydrogen gas as a direct source for the absorption of atomic hydrogen, the damaging effect can manifest itself from other hydrogen-containing gas species such as hydrogen sulfide (H2S), hydrogen chloride (HCl), and hydrogen bromide (HBr) environments. It has been known that H2S environment may result in a much more severe condition of embrittlement than pure hydrogen gas (H2) for certain types of alloys at similar conditions of stress and gas pressure. The reduction of fracture loads can occur at levels well below the yield strength of the material. Hydrogen embrittlement is usually manifest in terms of singular sharp cracks, in contrast to the extensive branching observed for stress corrosion cracking. The initial crack openings and the local deformation associated with crack propagation may be so small that they are difficult to detect except in special nondestructive examinations. Cracks due to HE can grow rapidly with little macroscopic evidence of mechanical deformation in materials that are normally quite ductile. This Technical Memorandum presents a comprehensive review of experimental data for the effects of gaseous Hydrogen Environment Embrittlement (HEE) for several types of metallic materials. Common material screening methods are used to rate the hydrogen degradation of mechanical properties that occur while the material is under an applied stress and exposed to gaseous hydrogen as compared to air or helium, under slow strain rates (SSR) testing. Due to the simplicity and accelerated nature of these tests, the results expressed in terms of HEE index are not intended to necessarily represent true hydrogen service environment for long-term exposure, but rather to provide a practical approach for material screening, which is a useful concept to qualitatively evaluate the severity of

  20. Apparatus and method for treating pollutants in a gas using hydrogen peroxide and UV light

    Science.gov (United States)

    Cooper, Charles David (Inventor); Clausen, Christian Anthony (Inventor)

    2005-01-01

    An apparatus for treating pollutants in a gas may include a source of hydrogen peroxide, and a treatment injector for creating and injecting dissociated hydrogen peroxide into the flow of gas. The treatment injector may further include an injector housing having an inlet, an outlet, and a hollow interior extending therebetween. The inlet may be connected in fluid communication with the source of hydrogen peroxide so that hydrogen peroxide flows through the hollow interior and toward the outlet. At least one ultraviolet (UV) lamp may be positioned within the hollow interior of the injector housing. The at least one UV lamp may dissociate the hydrogen peroxide flowing through the tube. The dissociated hydrogen peroxide may be injected into the flow of gas from the outlet for treating pollutants, such as nitrogen oxides.

  1. Silicon Carbide-Based Hydrogen Gas Sensors for High-Temperature Applications

    Directory of Open Access Journals (Sweden)

    Sangchoel Kim

    2013-10-01

    Full Text Available We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5 layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures.

  2. Silicon carbide-based hydrogen gas sensors for high-temperature applications.

    Science.gov (United States)

    Kim, Seongjeen; Choi, Jehoon; Jung, Minsoo; Joo, Sungjae; Kim, Sangchoel

    2013-10-09

    We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC) was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures.

  3. The reactions of ground and excited state sodium atoms with hydrogen halide molecules

    Science.gov (United States)

    Weiss, P. S.; Mestdagh, J. M.; Covinsky, M. H.; Balko, B. A.; Lee, Y. T.

    1988-10-01

    The reactions of ground and excited state Na atoms with hydrogen halide (HX) molecules have been studied using the crossed molecular beams method. With both increasing translational and increasing electronic energy, the reactive cross sections increase in the reactions of HCl and HBr. From product angular and velocity distributions detailed center-of-mass information is derived. For the reactions of Na (3 2S 1/2, 3 2P 1/2, 4 2D 5/2, 5 2S 1/2) with HCl, the product NaCl is back-scattered with respect to the incoming Na atom in the center-of-mass frame of reference. The reaction of each Na state studied with HCl is direct and proceeds via collinear and near-collinear Na-Cl-H approach geometries. For the Na (3 2P 3/2) and Na (4 2D 5/2) reactions with HCl the predominant transition state symmetry is 2Σ in a collinear (C ∞ν) Na-Cl-H geometry. This is consistent with the reaction proceeding via electron transfer from the Na atom to the halide atom. Absolute reactive cross sections for each state of Na studied with HCl were determined by comparison with both small and large angle elastic scattering. We were unable to observe Na atoms with over 4 eV of electronic energy react with HF up to collision energies of 13 kcal/mole.

  4. A theoretical study of hydrogen atoms adsorption and diffusion on PuO{sub 2} (110) surface

    Energy Technology Data Exchange (ETDEWEB)

    Yu, H.L., E-mail: yuhuilong2002@126.com; Tang, T.; Zheng, S.T.; Shi, Y.; Qiu, R.Z.; Luo, W.H.; Meng, D.Q.

    2016-05-05

    The mechanisms of adsorption and diffusion of hydrogen atoms on the PuO{sub 2} (110) surface are investigated by density functional theory corrected for onsite Coulombic interactions (GGA + U). In order to find out the energetically more favorable adsorption site and optimum diffusion path, adsorption energy of atomic H on various sites and the diffusion energy barrier are derived and compared. Our results show that both chemisorption and physisorption exist for H atoms adsorption configurations on PuO{sub 2} (110) surface. Two processes for H diffusion are investigated using the climbing nudged-elastic-band (cNEB) approach. We have identified two diffusion mechanisms, leading to migration of atomic H on the surface and diffusion from surface to subsurface. The energy barriers indicate that it is energetically more favorable for H atom to be on the surface. Hydrogen permeation through purity PuO{sub 2} surface is mainly inhibited from hydrogen atom diffusion from surface to subsurface. - Highlights: • H atoms adsorption on PuO{sub 2} (110) surface are investigated by GGA + U. • Both chemisorption and physisorption exist for H atoms adsorption configurations. • H atoms migration into PuO{sub 2} (100) surface are inhibited with the barrier of 2.15 eV. • H atoms diffusion on PuO{sub 2} (110) surface are difficult at room temperature.

  5. Atomic ionization of hydrogen-like ions by twisted photons: angular distribution of emitted electrons

    Science.gov (United States)

    Matula, O.; Hayrapetyan, A. G.; Serbo, V. G.; Surzhykov, A.; Fritzsche, S.

    2013-10-01

    We investigate the angular distribution of electrons that are emitted in the ionization of hydrogen-like ions by twisted photons. Analysis is performed based on the first-order perturbation theory and the non-relativistic Schrödinger equation. Special attention is paid to the dependence of the electron emission pattern on the impact parameter b of the ion with respect to the centre of the twisted wave front. In order to explore such a dependence, detailed calculations were carried out for the photoionization of the 1s ground and 2 py excited states of neutral hydrogen atoms. Based on these calculations, we argue that for relatively small impact parameters, the electron angular distributions may be strongly affected by altering the position of the atom within the wave front. In contrast, if the atom is placed far from the front centre, the emission pattern of the electrons is independent of the impact parameter b and resembles that observed in the photoionization by plane wave photons.

  6. Investigating the role of atomic hydrogen on chloroethene reactions with iron using tafel analysis and electrochemical impedance spectroscopy.

    Science.gov (United States)

    Wang, Jiankang; Farrell, James

    2003-09-01

    Metallic iron filings are commonly employed as reducing agents in permeable barriers used for remediating groundwater contaminated by chlorinated solvents. Reactions of trichloroethylene (TCE) and tetrachloroethylene (PCE) with zerovalent iron were investigated to determine the role of atomic hydrogen in their reductive dechlorination. Experiments simultaneously measuring dechlorination and iron corrosion rates were performed to determine the fractions of the total current going toward dechlorination and hydrogen evolution. Corrosion rates were determined using Tafel analysis, and dechlorination rates were determined from rates of byproduct generation. Electrochemical impedance spectroscopy (EIS) was used to determine the number of reactions that controlled the observed rates of chlorocarbon disappearance, as well as the role of atomic hydrogen in TCE and PCE reduction. Comparison of iron corrosion rates with those for TCE reaction showed that TCE reduction occurred almost exclusively via atomic hydrogen at low pH values and via atomic hydrogen and direct electron transfer at neutral pH values. In contrast, reduction of PCE occurred primarily via direct electron transfer at both low and neutral pH values. At low pH values and micromolar concentrations, TCE reaction rates were faster than those for PCE due to more rapid reduction of TCE by atomic hydrogen. At neutral pH values and millimolar concentrations, PCE reaction rates were faster than those for TCE. This shift in relative reaction rates was attributed to a decreasing contribution of the atomic hydrogen reaction mechanism with increasing halocarbon concentrations and pH values. The EIS data showed that all the rate limitations for TCE and PCE dechlorination occurred during the transfer of the first two electrons. Results from this study show that differences in relative reaction rates of TCE and PCE with iron are dependent on the significance of the reduction pathway involving atomic hydrogen.

  7. Hydrogen atom transfer reactions in thiophenol: photogeneration of two new thione isomers.

    Science.gov (United States)

    Reva, Igor; Nowak, Maciej J; Lapinski, Leszek; Fausto, Rui

    2015-02-21

    Photoisomerization reactions of monomeric thiophenol have been investigated for the compound isolated in low-temperature argon matrices. The initial thiophenol population consists exclusively of the thermodynamically most stable thiol form. Phototransformations were induced by irradiation of the matrices with narrowband tunable UV light. Irradiation at λ > 290 nm did not induce any changes in isolated thiophenol molecules. Upon irradiation at 290-285 nm, the initial thiol form of thiophenol converted into its thione isomer, cyclohexa-2,4-diene-1-thione. This conversion occurs by transfer of an H atom from the SH group to a carbon atom at the ortho position of the ring. Subsequent irradiation at longer wavelengths (300-427 nm) demonstrated that this UV-induced hydrogen-atom transfer is photoreversible. Moreover, upon irradiation at 400-425 nm, the cyclohexa-2,4-diene-1-thione product converts, by transfer of a hydrogen atom from the ortho to para position, into another thione isomer, cyclohexa-2,5-diene-1-thione. The latter thione isomer is also photoreactive and is consumed if irradiated at λ atom-transfer isomerization reactions dominate the unimolecular photochemistry of thiophenol confined in a solid argon matrix. A set of low-intensity infrared bands, observed in the spectra of UV irradiated thiophenol, indicates the presence of a phenylthiyl radical with an H- atom detached from the SH group. Alongside the H-atom-transfer and H-atom-detachment processes, the ring-opening photoreaction occurred in cyclohexa-2,4-diene-1-thione by the cleavage of the C-C bond at the alpha position with respect to the thiocarbonyl C[double bond, length as m-dash]S group. The resulting open-ring conjugated thioketene adopts several isomeric forms, differing by orientations around single and double bonds. The species photogenerated upon UV irradiation of thiophenol were identified by comparison of their experimental infrared spectra with the spectra theoretically calculated for

  8. Space hardware compatibility tests with hydrogen peroxide gas plasma sterilization

    Science.gov (United States)

    Faye, Delphine; Aguila, Alexandre; Debus, Andre; Remaury, Stephanie; Nabarra, Pascale; Darbord, Jacques C.; Soufflet, Caroline; Destrez, Philippe; Coll, Patrice; Coscia, David

    The exploration of the Solar System shall comply with planetary protection requirements handled presently by the Committee of Space Research (COSPAR). The goal of planetary protection is to protect celestial bodies from terrestrial contamination and also to protect the Earth environment from an eventual contamination carried by return samples or by space systems. For project teams, avoiding the biological contamination of other Solar System bodies such as Mars imposes to perform unusual tasks at technical and operational constraints point of view. The main are the reduction of bioburden on space hardware, the sterile integration of landers, the control of the biological cleanliness and the limitation of crash probability. In order to reduce the bioburden on spacecraft, the use of qualified sterilization processes may be envisaged. Since 1992 now, with the Mars96 mission, one of the most often used is the Sterrad(R) process working with hydrogen peroxide gas plasma. In the view of future Mars exploration programs, after tests performed in the frame of previous missions, a new test campaign has been performed on thermal coatings and miscellaneous materials coming from an experiment in order to assess the compatibility of space hardware and material with this sterilization process.

  9. Manganese-Oxygen Intermediates in O-O Bond Activation and Hydrogen-Atom Transfer Reactions.

    Science.gov (United States)

    Rice, Derek B; Massie, Allyssa A; Jackson, Timothy A

    2017-11-21

    Biological systems capitalize on the redox versatility of manganese to perform reactions involving dioxygen and its derivatives superoxide, hydrogen peroxide, and water. The reactions of manganese enzymes influence both human health and the global energy cycle. Important examples include the detoxification of reactive oxygen species by manganese superoxide dismutase, biosynthesis by manganese ribonucleotide reductase and manganese lipoxygenase, and water splitting by the oxygen-evolving complex of photosystem II. Although these enzymes perform very different reactions and employ structurally distinct active sites, manganese intermediates with peroxo, hydroxo, and oxo ligation are commonly proposed in catalytic mechanisms. These intermediates are also postulated in mechanisms of synthetic manganese oxidation catalysts, which are of interest due to the earth abundance of manganese. In this Account, we describe our recent efforts toward understanding O-O bond activation pathways of Mn III -peroxo adducts and hydrogen-atom transfer reactivity of Mn IV -oxo and Mn III -hydroxo complexes. In biological and synthetic catalysts, peroxomanganese intermediates are commonly proposed to decay by either Mn-O or O-O cleavage pathways, although it is often unclear how the local coordination environment influences the decay mechanism. To address this matter, we generated a variety of Mn III -peroxo adducts with varied ligand environments. Using parallel-mode EPR and Mn K-edge X-ray absorption techniques, the decay pathway of one Mn III -peroxo complex bearing a bulky macrocylic ligand was investigated. Unlike many Mn III -peroxo model complexes that decay to oxo-bridged-Mn III Mn IV dimers, decay of this Mn III -peroxo adduct yielded mononuclear Mn III -hydroxo and Mn IV -oxo products, potentially resulting from O-O bond activation of the Mn III -peroxo unit. These results highlight the role of ligand sterics in promoting the formation of mononuclear products and mark an important

  10. Analysis of atomic force microscopy phase data to dynamically detect adsorbed hydrogen under ambient conditions.

    Science.gov (United States)

    Young, Matthew J; Pfromm, Peter H; Rezac, Mary E; Law, Bruce M

    2014-10-14

    Characterization of the interactions of hydrogen with catalytic metal surfaces and the mass transfer processes involved in heterogeneous catalysis are important for catalyst development. Although a range of technologies for studying catalytic surfaces exist, much of it relies on high-vacuum conditions that preclude in situ research. In contrast, atomic force microscopy (AFM) provides an opportunity for direct observation of surfaces under or near actual reaction conditions. Tapping-mode AFM was explored here because it expands AFM beyond the usual topographic information toward speciation and other more subtle surface information. This work describes using phase-angle information from tapping-mode AFM to follow the interactions of hydrogen with palladium, polycarbonate, and iron. Real-time AFM phase-angle information allowed for the observation of multiphase mass transfer to and from the surface of palladium at atmospheric pressure and room temperature without the need for complex sample preparation. The AFM observations are quantitatively benchmarked against and confirm mass transfer predictions based on bulk hydrogen diffusion data. Additionally, they support recent studies that demonstrate the existence of multiple hydrogen states during interactions with palladium surfaces.

  11. Atomic-Scale Mechanism of Efficient Hydrogen Evolution at SiC Nanocrystal Electrodes.

    Science.gov (United States)

    Shen, Xiao; Pantelides, Sokrates T

    2013-01-03

    Efficient electrochemical hydrogen evolution at ultrathin 3C-SiC nanocrystal electrodes in acid solutions was recently reported, but the atomic-scale mechanism of the reaction was not identified. Here we report quantum mechanical calculations of pertinent reactions and show that the reaction happens at pre-existing hydrogenated surface Si-H sites through a mechanism that is related to the Volmer-Heyrovsky mechanism that occurs in metals. Here the Heyrovsky reaction occurs as the first step, where an electron from the substrate reacts with a hydronium adsorbed at a Si-H site, creating an H2 molecule and a Si dangling bond. The Volmer reaction follows and regenerates the Si-H. This ordering of reactions is supported by the fact that the hydrogen coverage on SiC electrodes does not depend on the applied voltage, in contrast to the cases of metal electrodes. Moreover, the Volmer reaction, which is a one-step process on metal surface, is a two-step process here. We then show that the rise of the conduction band due to quantum confinement accounts for the fact that only ultrasmall SiC nanocrystals are electrochemically active. We also show that the ability of a Si-H bond to bind a hydronium is essential for the hydrogen evolution to occur at high rate.

  12. Experimental limits on the velocities of sodium atoms sputtered from solid surfaces by hydrogen ions. [Na cloud production around Io

    Science.gov (United States)

    Stoner, J. O., Jr.

    1976-01-01

    Optical emission at 589.0 nm by sodium atoms sputtered from solid targets by hydrogen molecular ions was observed, and no accompanying broadening or shifts of this line could be detected relative to that from a laboratory lamp. This allowed an upper limit of about 500,000 cm/sec on the mean speed of ejected sodium atoms to be calculated. The results are consistent with the hypothesis that the atomic sodium cloud surrounding Io is produced by this mechanism.

  13. Comment on "Entropy and complexity analysis of hydrogenic Rydberg atoms" [J. Math. Phys. 54, 052109 (2013)

    Science.gov (United States)

    Jiao, Li Guang; Zan, Li Rong

    2017-10-01

    In a recent paper [S. López-Rosa et al., J. Math. Phys. 54, 052109 (2013)], the authors made detailed investigations on the information-theoretic quantities for hydrogenic atoms in Rydberg states. Asymptotic forms of different types of complexity measures (Crámer-Rao, Fisher-Shannon, and LMC types) in both position and momentum spaces were obtained for hydrogenic states (n,l,m) with fixed l and increasingly large n. However, the expressions for the Crámer-Rao complexity are incorrect due to the wrong definition of variance. The correct form of this complexity in position space is presented exactly in this work. In momentum space, two different definitions of variance are provided and corresponding Crámer-Rao complexities are discussed separately. In either case, the momentum complexity increases much faster than that in position space when increasing principal quantum number n.

  14. Atomic configuration and charge state of hydrogen at dislocations in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Vysotskii, N. V., E-mail: mrdestroyed@yandex.ru; Loshachenko, A. S., E-mail: a.loshachenko@spbu.ru; Vyvenko, O. F., E-mail: vyvenko@gmail.com [St. Petersburg State University (Russian Federation)

    2017-03-15

    The effect of the introduction of hydrogen upon the vibration spectra and electrical characteristics of samples with dislocation networks at the interface of bonded silicon wafers was studied. In order to improve the sensitivity of measurements and to distinguish the signal from dislocation networks in Raman spectra, thin foils conventionally prepared for transmission electron microscopy were used as the sample under investigation. In the samples with dislocation networks, a Raman peak at 2000 cm{sup –1} was observed. This peak survived after annealing at a temperature of T = 500°C and was not observed in reference samples. Comparison of the experimental data with currently available theoretical calculations allowed one to attribute the observed peak to neutral hydrogen atoms H{sup 0} at the center of Si–Si bonds. The peak is metastable in the ideal lattice, but becomes stable in the vicinity of dislocations.

  15. Spin–spin correlations and entanglement in elastic electron scattering from hydrogen atoms

    Science.gov (United States)

    Bartschat, Klaus

    2017-11-01

    In two recent papers, Blum and Lohmann (2016 Phys. Rev. Lett. 116 033201) and Lohmann et al (2016 Phys. Rev. A 94 032331), the possibility of continuously varying the degree of entanglement between an elastically scattered electron and the valence electron of quasi-one electron targets was discussed. Here we present results for elastic electron scattering from atomic hydrogen in the energy regime of 1‑10 eV and the full range of scattering angles 0^\\circ -180^\\circ . We confirm previous calculations at very low energies, which predicted that the hydrogen target is not a promising candidate for Bell correlations through electron collisions. This finding remains unchanged in the near-resonance regime of incident electron energies just below 10 eV. In addition to the spin-correlation parameter P, we present the angle-integrated total cross section, as well as the angle-differential cross section at a few representative collision energies.

  16. Time-resolved X-ray scattering by electronic wave packets: analytic solutions to the hydrogen atom

    DEFF Research Database (Denmark)

    Simmermacher, Mats; Henriksen, Niels Engholm; Møller, Klaus Braagaard

    2017-01-01

    description of time-resolved X-ray scattering by non-stationary electronic wave packets in atomic systems. A consistent application of the Waller-Hartree approximation is discussed and different contributions to the total differential scattering signal are identified and interpreted. Moreover......, it is demonstrated how the scattering signal of wave packets in the hydrogen atom can be expressed analytically. This permits simulations without numerical integration and establishes a benchmark for both efficiency and accuracy. Based on that, scattering patterns of an exemplary wave packet in the hydrogen atom...

  17. Spatial distribution of atomic and ion hydrogen flux and its effect on hydrogen recycling in long duration confined and non-confined plasmas

    Directory of Open Access Journals (Sweden)

    A. Kuzmin

    2017-08-01

    Full Text Available In order to understand the atomic hydrogen distribution in different kinds of plasma and its influence on the recycling, two kinds of plasmas were used: non-confined annular electron cyclotron resonance (ECR and confined long duration plasmas. The permeation probes are used to measure directly the atomic hydrogen flux at several poloidal positions. The permeation through metals due to the ion and atom component of the hydrogen flux to the wall is indistinguishable. To estimate the contribution of the ions directly, Langmuir probes were used. The Гinc profile behind the plasma facing components (PFCs is almost constant, ∼2 ×1018 H/s/m2.

  18. 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.

  19. On the Treatment of l-changing Proton-hydrogen Rydberg Atom Collisions

    Science.gov (United States)

    Vrinceanu, Daniel; Onofrio, Roberto; Sadeghpour, Hossein

    2018-01-01

    Energy-conserving, angular momentum-changing collisions between protons and highly excited Rydberg hydrogen atoms are important for precise understanding of the primordial recombination cascade, and the elemental abundance.Early approaches to l-changing collisions used perturbation theory for only dipole-allowed (Δl = ±1) transitions. An exact non-perturbative quantum mechanical treatment is possible, but it comes at computational cost for highly excited Rydberg states. In this note we show how to obtain a semi-classical limit that is accurate and simple, and develop further physical insights afforded by the non-perturbative quantum mechanical treatment.

  20. Multiphoton resonant ionization of hydrogen atom exposed to two-colour laser pulses

    Institute of Scientific and Technical Information of China (English)

    Wang Pei-Jie; Fang Yan

    2008-01-01

    This paper studies the multiphoton resonant ionization by two-colour laser pulses in the hydrogen atom by solving the time-dependent Schr(o)dinger equation.By fixing the parameters of fundamental laser field and scanning the frequency of second laser field,it finds that the ionization probability shows several resonance peaks and is also much larger than the linear superposition of probabilities by applying two lasers separately.The enhancement of the ionization happens when the system is resonantly pumped to the excited states by absorbing two or more colour photons non-sequentially.

  1. Electron impact ionization of atomic hydrogen from the 1S and 2S states

    Energy Technology Data Exchange (ETDEWEB)

    Bartschat, K.; Bray, I.

    1996-05-01

    We present results from R-Matrix with Pseudo-States (RMPS) and Convergent Close-Coupling (CCC) calculations for electron impact total ionization of the 1S and 2S states of atomic hydrogen in the energy region from threshold to 100 eV. Particular attention is given to the near threshold region. We find the results for energies more than 2 eV above threshold to be in excellent agreement with the available experimental data. (authors). 19 refs., 3 figs.

  2. Interbasis expansion and SO(3) symmetry in the two-dimensional hydrogen atom.

    Energy Technology Data Exchange (ETDEWEB)

    Torres del Castillo, G.F.; Lopez Villanueva, A. [Universidad Autonoma de Puebla, Puebla (Mexico)

    2001-04-01

    Making use of the SO(3) symmetry of the two-dimensional hydrogen atom, each of the bases for the bound states formed by the separable solutions of the Schroedinger equation in polar and parabolic coordinates are expressed in terms of the other. [Spanish] Usando la simetria SO(3) del atomo de hidrogeno en dos dimensiones, cada una de las bases para los estados ligados formadas por las soluciones separables de la ecuacion de Schroedinger en coordenadas polares y parabolicas se expresan en terminos de la otra.

  3. Existence of a ground state for the confined hydrogen atom in non-relativistic QED

    DEFF Research Database (Denmark)

    Amour, Laurent; Faupin, Jeremy

    2008-01-01

    We consider a system of a hydrogen atom interacting with the quantized electromagnetic field. Instead of fixing the nucleus, we assume that the system is confined by its center of mass. This model is used in theoretical physics to explain the Lamb-Dicke effect. After a brief review...... of the literature, we explain how to verify some properly chosen binding conditions which, by [25], lead to the existence of a ground state for our model, and for all values of the fine-structure constant...

  4. The effect of moderators on the reactions of hot hydrogen atoms with methane

    CERN Document Server

    Estrup, Peder J.

    1960-01-01

    The reaction of recoil tritium with methane has been examined in further detail. The previous hypothesis that this system involves a hot displacement reaction of high kinetic energy hydrogen to give CH$_{3}$T, CH$_{2}$T and HT is confirmed. The effect of moderator on this process is studied by the addition of noble gases. As predicted these gases inhibit the hot reaction action, their efficiency in this respect being He > Ne > A > Se. The data are quantitatively in accord with a theory of hot atom kinetics. The mechanism of the hot displacement process is briefly discussed.

  5. Spontaneous light emission by atomic hydrogen: Fermi's golden rule without cheating

    Science.gov (United States)

    Debierre, V.; Durt, T.; Nicolet, A.; Zolla, F.

    2015-10-01

    Focusing on the 2 p- 1 s transition in atomic hydrogen, we investigate through first order perturbation theory the time evolution of the survival probability of an electron initially taken to be in the excited (2 p) state. We examine both the results yielded by the standard dipole approximation for the coupling between the atom and the electromagnetic field - for which we propose a cutoff-independent regularisation - and those yielded by the exact coupling function. In both cases, Fermi's golden rule is shown to be an excellent approximation for the system at hand: we found its maximal deviation from the exact behaviour of the system to be of order 10-8 /10-7. Our treatment also yields a rigorous prescription for the choice of the optimal cutoff frequency in the dipole approximation. With our cutoff, the predictions of the dipole approximation are almost indistinguishable at all times from the exact dynamics of the system.

  6. Hidden momentum in a hydrogen atom and the Lorentz-force law

    Science.gov (United States)

    Filho, J. S. Oliveira; Saldanha, Pablo L.

    2015-11-01

    By using perturbation theory, we show that a hydrogen atom with magnetic moment due to the orbital angular momentum of the electron has so-called hidden momentum in the presence of an external electric field. This means that the atomic electronic cloud has a nonzero linear momentum in its center-of-mass rest frame due to a relativistic effect. This is completely analogous to the hidden momentum that a classical current loop has in the presence of an external electric field. We discuss how this effect is essential for the validity of the Lorentz-force law in quantum systems. We also connect our results to the long-standing Abraham-Minkowski debate about the momentum of light in material media.

  7. Zeolite Membrane Reactor for Water Gas Shift Reaction for Hydrogen Production

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jerry Y.S. [Arizona State Univ., Mesa, AZ (United States)

    2013-01-29

    Gasification of biomass or heavy feedstock to produce hydrogen fuel gas using current technology is costly and energy-intensive. The technology includes water gas shift reaction in two or more reactor stages with inter-cooling to maximize conversion for a given catalyst volume. This project is focused on developing a membrane reactor for efficient conversion of water gas shift reaction to produce a hydrogen stream as a fuel and a carbon dioxide stream suitable for sequestration. The project was focused on synthesizing stable, hydrogen perm-selective MFI zeolite membranes for high temperature hydrogen separation; fabricating tubular MFI zeolite membrane reactor and stable water gas shift catalyst for membrane reactor applications, and identifying experimental conditions for water gas shift reaction in the zeolite membrane reactor that will produce a high purity hydrogen stream. The project has improved understanding of zeolite membrane synthesis, high temperature gas diffusion and separation mechanisms for zeolite membranes, synthesis and properties of sulfur resistant catalysts, fabrication and structure optimization of membrane supports, and fundamentals of coupling reaction with separation in zeolite membrane reactor for water gas shift reaction. Through the fundamental study, the research teams have developed MFI zeolite membranes with good perm-selectivity for hydrogen over carbon dioxide, carbon monoxide and water vapor, and high stability for operation in syngas mixture containing 500 part per million hydrogen sulfide at high temperatures around 500°C. The research teams also developed a sulfur resistant catalyst for water gas shift reaction. Modeling and experimental studies on the zeolite membrane reactor for water gas shift reaction have demonstrated the effective use of the zeolite membrane reactor for production of high purity hydrogen stream.

  8. Significant change of local atomic configurations at surface of reduced activation Eurofer steels induced by hydrogenation treatments

    Energy Technology Data Exchange (ETDEWEB)

    Greculeasa, S.G.; Palade, P.; Schinteie, G. [National Institute for Materials Physics, P.O. Box MG-7, 77125, Bucharest-Magurele (Romania); Kuncser, A.; Stanciu, A. [National Institute for Materials Physics, P.O. Box MG-7, 77125, Bucharest-Magurele (Romania); University of Bucharest, Faculty of Physics, 77125, Bucharest-Magurele (Romania); Lungu, G.A. [National Institute for Materials Physics, P.O. Box MG-7, 77125, Bucharest-Magurele (Romania); Porosnicu, C.; Lungu, C.P. [National Institute for Laser, Plasma and Radiation Physics, 77125, Bucharest-Magurele (Romania); Kuncser, V., E-mail: kuncser@infim.ro [National Institute for Materials Physics, P.O. Box MG-7, 77125, Bucharest-Magurele (Romania)

    2017-04-30

    Highlights: • Engineering of Eurofer slab properties by hydrogenation treatments. • Hydrogenation modifies significantly the local atomic configurations at the surface. • Hydrogenation increases the expulsion of the Cr atoms toward the very surface. • Approaching binomial atomic distribution by hydrogenation in the next surface 100 nm. - Abstract: Reduced-activation steels such as Eurofer alloys are candidates for supporting plasma facing components in tokamak-like nuclear fusion reactors. In order to investigate the impact of hydrogen/deuterium insertion in their crystalline lattice, annealing treatments in hydrogen atmosphere have been applied on Eurofer slabs. The resulting samples have been analyzed with respect to local structure and atomic configuration both before and after successive annealing treatments, by X-ray diffractometry (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and conversion electron Mössbauer spectroscopy (CEMS). The corroborated data point out for a bcc type structure of the non-hydrogenated alloy, with an average alloy composition approaching Fe{sub 0.9}Cr{sub 0.1} along a depth of about 100 nm. EDS elemental maps do not indicate surface inhomogeneities in concentration whereas the Mössbauer spectra prove significant deviations from a homogeneous alloying. The hydrogenation increases the expulsion of the Cr atoms toward the surface layer and decreases their oxidation, with considerable influence on the surface properties of the steel. The hydrogenation treatment is therefore proposed as a potential alternative for a convenient engineering of the surface of different Fe-Cr based alloys.

  9. First Operating Results of a Dynamic Gas Bearing Turbine in AN Industrial Hydrogen Liquefier

    Science.gov (United States)

    Bischoff, S.; Decker, L.

    2010-04-01

    Hydrogen has been brought into focus of industry and public since fossil fuels are depleting and costs are increasing dramatically. Beside these issues new high-tech processes in the industry are in need for hydrogen at ultra pure quality. To achieve these requirements and for efficient transportation, hydrogen is liquefied in industrial plants. Linde Gas has commissioned a new 5.5 TPD Hydrogen liquefier in Leuna, Germany, which has been engineered and supplied by Linde Kryotechnik. One of the four expansion turbines installed in the liquefaction process is equipped with dynamic gas bearings. Several design features and operational characteristics of this application will be discussed. The presentation will include results of efficiency and operational reliability that have been determined from performance tests. The advantages of the Linde dynamic gas bearing turbine for future use in hydrogen liquefaction plants will be shown.

  10. Development of an Inexpensive RGB Color Sensor for the Detection of Hydrogen Cyanide Gas.

    Science.gov (United States)

    Greenawald, Lee A; Boss, Gerry R; Snyder, Jay L; Reeder, Aaron; Bell, Suzanne

    2017-10-27

    An inexpensive red, green, blue (RGB) color sensor was developed for detecting low ppm concentrations of hydrogen cyanide gas. A piece of glass fiber filter paper containing monocyanocobinamide [CN(H2O)Cbi] was placed directly above the RGB color sensor and an on chip LED. Light reflected from the paper was monitored for RGB color change upon exposure to hydrogen cyanide at concentrations of 1.0-10.0 ppm as a function of 25%, 50%, and 85% relative humidity. A rapid color change occurred within 10 s of exposure to 5.0 ppm hydrogen cyanide gas (near the NIOSH recommended exposure limit). A more rapid color change occurred at higher humidity, suggesting a more effective reaction between hydrogen cyanide and CN(H2O)Cbi. The sensor could provide the first real time respirator end-of-service-life alert for hydrogen cyanide gas.

  11. Modification and testing of an engine and fuel control system for a hydrogen fuelled gas turbine

    Science.gov (United States)

    Funke, H. H.-W.; Börner, S.; Hendrick, P.; Recker, E.

    2011-10-01

    The control of pollutant emissions has become more and more important by the development of new gas turbines. The use of hydrogen produced by renewable energy sources could be an alternative. Besides the reduction of NOx emissions emerged during the combustion process, another major question is how a hydrogen fuelled gas turbine including the metering unit can be controlled and operated. This paper presents a first insight in modifications on an Auxiliary Power Unit (APU) GTCP 36300 for using gaseous hydrogen as a gas turbine fuel. For safe operation with hydrogen, the metering of hydrogen has to be fast, precise, and secure. So, the quality of the metering unit's control loop has an important influence on this topic. The paper documents the empiric determination of the proportional integral derivative (PID) control parameters for the metering unit.

  12. 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

  13. Absolute detection of metastable rare gas atoms by a cw laser photoionization method

    NARCIS (Netherlands)

    Schohl, S.; Klar, D.; Kraft, T.; Meijer, H.A.J.; Ruf, M.-W.; Schmitz, U.; Smith, S.J.; Hotop, H.

    1991-01-01

    A novel, accurate method for the absolute detection of metastable rare gas atoms is described and demonstrated. It involves a direct in situ determination of the electron emission coefficient γ for impact of the respective metastable atom on a conducting surface, γ is reliably obtained by a cw

  14. Enzymatic production of hydrogen gas from glucose and cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Mattingly, S.M.; Woodward, J. [Oak Ridge National Lab., TN (United States)

    1996-10-01

    An enzymatic process has been used to convert glucose to molecular hydrogen with the ultimate goal of converting cellulose to hydrogen. Two enzymes from the Archae, Thermoplasma acidophilium glucose dehydrogenase (GDH) and Pyrococcus furiosus hydrogenase, were used to oxidize glucose and NADPH respectively, resulting in the formation of molecular hydrogen. The stoichiometric yield of hydrogen from glucose was close to the theoretical maximum expected. Further, the molar amount of hydrogen produced was greater than the molar equivalent of NADP{sup +} present in the reaction mixture indicating that this GDH cofactor was regenerated throughout the course of the reaction. Hydrogen was also shown to be produced from cellulose if cellulase was included in the reaction mixture.

  15. Inspection of the hydrogen gas pressure with metal shield by cold neutron radiography at CMRR

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hang; Cao, Chao; Huo, Heyong; Wang, Sheng; Wu, Yang; Yin, Wei; Sun, Yong; Liu, Bin; Tang, Bin [Institute of Nuclear Physics and Chemistry, Chinese Academy of Engineering Physics, Mianyang (China); Key Laboratory of Neutron Physics, Chinese Academy of Engineering Physics, Mianyang (China)

    2017-04-11

    The inspection of the process of gas pressure change is important for some applications (e.g. gas tank stockpile or two phase fluid model) which need quantitative and non-touchable measurement. Neutron radiography provides a suitable tool for such investigations with nice resolution. The quantitative cold neutron radiography (CNR) is developed at China Mianyang Research Reactor (CMRR) to measure the hydrogen gas pressure with metal shield. Because of the high sensitivity to hydrogen, even small change of the hydrogen pressure can be inspected by CNR. The dark background and scattering neutron effect are both corrected to promote measurement precision. The results show that CNR can measure the hydrogen gas pressure exactly and the pressure value average relative error between CNR and barometer is almost 1.9%.

  16. Inspection of the hydrogen gas pressure with metal shield by cold neutron radiography at CMRR

    Science.gov (United States)

    Li, Hang; Cao, Chao; Huo, Heyong; Wang, Sheng; Wu, Yang; Yin, Wei; Sun, Yong; Liu, Bin; Tang, Bin

    2017-04-01

    The inspection of the process of gas pressure change is important for some applications (e.g. gas tank stockpile or two phase fluid model) which need quantitative and non-touchable measurement. Neutron radiography provides a suitable tool for such investigations with nice resolution. The quantitative cold neutron radiography (CNR) is developed at China Mianyang Research Reactor (CMRR) to measure the hydrogen gas pressure with metal shield. Because of the high sensitivity to hydrogen, even small change of the hydrogen pressure can be inspected by CNR. The dark background and scattering neutron effect are both corrected to promote measurement precision. The results show that CNR can measure the hydrogen gas pressure exactly and the pressure value average relative error between CNR and barometer is almost 1.9%.

  17. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: BIOQUELL, INC. CLARIS C HYDROGEN PEROXIDE GAS GENERATOR

    Science.gov (United States)

    The Environmental Technology Verification report discusses the technology and performance of the Clarus C Hydrogen Peroxide Gas Generator, a biological decontamination device manufactured by BIOQUELL, Inc. The unit was tested by evaluating its ability to decontaminate seven types...

  18. Silicon carbide-based hydrogen gas sensors for high-temperature applications

    National Research Council Canada - National Science Library

    Kim, Seongjeen; Choi, Jehoon; Jung, Minsoo; Joo, Sungjae; Kim, Sangchoel

    2013-01-01

    .... In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC...

  19. Surface atomic relaxation and magnetism on hydrogen-adsorbed Fe(110) surfaces from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Chohan, Urslaan K.; Jimenez-Melero, Enrique [School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Dalton Cumbrian Facility, The University of Manchester, Moor Row CA24 3HA (United Kingdom); Koehler, Sven P.K., E-mail: sven.koehler@manchester.ac.uk [Dalton Cumbrian Facility, The University of Manchester, Moor Row CA24 3HA (United Kingdom); School of Chemistry, The University of Manchester, Manchester M13 9PL (United Kingdom); Photon Science Institute, The University of Manchester, Manchester M13 9PL (United Kingdom)

    2016-11-30

    Highlights: • Potential energy surfaces for H diffusion on Fe(110) calculated. • Full vibrational analysis of surface modes performed. • Vibrational analysis establishes lb site as a transition state to the 3f site. • Pronounced buckling observed in the Fe surface layer. - Abstract: We have computed adsorption energies, vibrational frequencies, surface relaxation and buckling for hydrogen adsorbed on a body-centred-cubic Fe(110) surface as a function of the degree of H coverage. This adsorption system is important in a variety of technological processes such as the hydrogen embrittlement in ferritic steels, which motivated this work, and the Haber–Bosch process. We employed spin-polarised density functional theory to optimise geometries of a six-layer Fe slab, followed by frozen mode finite displacement phonon calculations to compute Fe–H vibrational frequencies. We have found that the quasi-threefold (3f) site is the most stable adsorption site, with adsorption energies of ∼3.0 eV/H for all coverages studied. The long-bridge (lb) site, which is close in energy to the 3f site, is actually a transition state leading to the stable 3f site. The calculated harmonic vibrational frequencies collectively span from 730 to 1220 cm{sup −1}, for a range of coverages. The increased first-to-second layer spacing in the presence of adsorbed hydrogen, and the pronounced buckling observed in the Fe surface layer, may facilitate the diffusion of hydrogen atoms into the bulk, and therefore impact the early stages of hydrogen embrittlement in steels.

  20. Observation by conductive-probe atomic force microscopy of strongly inverted surface layers at the hydrogenated amorphous silicon/crystalline silicon heterojunctions

    Science.gov (United States)

    Maslova, O. A.; Alvarez, J.; Gushina, E. V.; Favre, W.; Gueunier-Farret, M. E.; Gudovskikh, A. S.; Ankudinov, A. V.; Terukov, E. I.; Kleider, J. P.

    2010-12-01

    Heterojunctions made of hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si) are examined by conducting probe atomic force microscopy. Conductive channels at both (n )a-Si:H/(p)c-Si and (p)a-Si:H/(n)c-Si interfaces are clearly revealed. These are attributed to two-dimension electron and hole gases due to strong inversion layers at the c-Si surface in agreement with previous planar conductance measurements. The presence of a hole gas in (p )a-Si:H/(n)c-Si structures implies a quite large valence band offset (EVc-Si-EVa-Si:H>0.25 eV).

  1. Generation of oxy-hydrogen gas and its effect on performance of spark ignition engine

    Science.gov (United States)

    Patil, N. N.; Chavan, C. B.; More, A. S.; Baskar, P.

    2017-11-01

    Considering the current scenario of petroleum fuels, it has been observed that, they will last for few years from now. On the other hand, the ever increasing cost of a gasoline fuels and their related adverse effects on environment caught the attention of researchers to find a supplementary source. For commercial fuels, supplementary source is not about replacing the entire fuel, instead enhancing efficiency by simply making use of it in lesser amount. From the recent research that has been carried out, focus on the use of Hydrogen rich gas as a supplementary source of fuel has increased. But the problem related to the storage of hydrogen gas confines the application of pure hydrogen in petrol engine. Using oxy-hydrogen gas (HHO) generator the difficulties of storing the hydrogen have overcome up to a certain limit. The present study highlights on performance evaluation of conventional petrol engine by using HHO gas as a supplementary fuel. HHO gas was generated from the electrolysis of water. KOH solution of 3 Molar concentration was used which act as a catalyst and accelerates the rate of generation of HHO gas. Quantity of gas to be supplied to the engine was controlled by varying amount of current. It was observed that, engine performance was improved on the introduction of HHO gas.

  2. Relationship between the variations of hydrogen in HCNG fuel and the oxygen in exhausted gas

    OpenAIRE

    Preecha Yaom; Sarawoot Watechagit

    2015-01-01

    The variation of the mixing ratio between hydrogen and compressed natural gas (CNG) in hydrogen enriched compressed natural gas fuel (HCNG) gives different results in terms of engine performances, fuel consumption, and emission characteristics. Therefore, the engine performance using HCNG as fuel can be optimized if the mixing ratio between the two fuels in HCNG can be adjusted in real time while the engine is being operated. In this research, the relationship between the amount of oxygen in ...

  3. Chemical Kinetics of Hydrogen Atom Abstraction from Allylic Sites by3O2; Implications for Combustion Modeling and Simulation.

    Science.gov (United States)

    Zhou, Chong-Wen; Simmie, John M; Somers, Kieran P; Goldsmith, C Franklin; Curran, Henry J

    2017-03-09

    Hydrogen atom abstraction from allylic C-H bonds by molecular oxygen plays a very important role in determining the reactivity of fuel molecules having allylic hydrogen atoms. Rate constants for hydrogen atom abstraction by molecular oxygen from molecules with allylic sites have been calculated. A series of molecules with primary, secondary, tertiary, and super secondary allylic hydrogen atoms of alkene, furan, and alkylbenzene families are taken into consideration. Those molecules include propene, 2-butene, isobutene, 2-methylfuran, and toluene containing the primary allylic hydrogen atom; 1-butene, 1-pentene, 2-ethylfuran, ethylbenzene, and n-propylbenzene containing the secondary allylic hydrogen atom; 3-methyl-1-butene, 2-isopropylfuran, and isopropylbenzene containing tertiary allylic hydrogen atom; and 1-4-pentadiene containing super allylic secondary hydrogen atoms. The M06-2X/6-311++G(d,p) level of theory was used to optimize the geometries of all of the reactants, transition states, products and also the hinder rotation treatments for lower frequency modes. The G4 level of theory was used to calculate the electronic single point energies for those species to determine the 0 K barriers to reaction. Conventional transition state theory with Eckart tunnelling corrections was used to calculate the rate constants. The comparison between our calculated rate constants with the available experimental results from the literature shows good agreement for the reactions of propene and isobutene with molecular oxygen. The rate constant for toluene with O 2 is about an order magnitude slower than that experimentally derived from a comprehensive model proposed by Oehlschlaeger and coauthors. The results clearly indicate the need for a more detailed investigation of the combustion kinetics of toluene oxidation and its key pyrolysis and oxidation intermediates. Despite this, our computed barriers and rate constants retain an important internal consistency. Rate constants

  4. STEREO Observations of Energetic Neutral Hydrogen Atoms during the 5 December 2006 Solar Flare

    Science.gov (United States)

    Mewaldt, R. A.; Leske, R. A.; Stone, E. C.; Barghouty, A. F.; Labrador, A. W.; Cohen, C. M. S.; Cummings, A. C.; Davis, A. J.; vonRosenvinge, T. T.; Wiedenbeck, M. E.

    2009-01-01

    We report the discovery of energetic neutral hydrogen atoms emitted during the X9 solar event of December 5, 2006. Beginning 1 hour following the onset of this E79 flare, the Low Energy Telescopes (LETs) on both the STEREO A and B spacecraft observed a sudden burst of 1.6 to 15 MeV protons beginning hours before the onset of the main solar energetic particle (SEP) event at Earth. More than 70% of these particles arrived from a longitude within 10 of the Sun, consistent with the measurement resolution. The derived emission profile at the Sun had onset and peak times remarkably similar to the GOES soft X-ray profile and continued for more than an hour. The observed arrival directions and energy spectrum argue strongly that the particle events less than 5 MeV were due to energetic neutral hydrogen atoms (ENAs). To our knowledge, this is the first reported observation of ENA emission from a solar flare/coronal mass ejection. Possible origins for the production of ENAs in a large solar event are considered. We conclude that the observed ENAs were most likely produced in the high corona and that charge-transfer reactions between accelerated protons and partially-stripped coronal ions are an important source of ENAs in solar events.

  5. Observations and Interpretations of Energetic Neutral Hydrogen Atoms from the December 5, 2006 Solar Event

    Science.gov (United States)

    Mewaldt, R. A.; Leske, R. A.; Shih, A. Y.; Stone, E. C.; Barghouty, A. f.; Cohen, C. M. S.; Cummings, A. c.; Labrador, A. W.; vonRosenvinge, T. T.

    2009-01-01

    We discuss recently reported observations of energetic neutral hydrogen atoms (ENAs) from an X9 solar flare/coronal mass ejection event on 5 December 2006, located at E79. The observations were made by the Low Energy Telescopes (LETs) on STEREO A and B. Prior to the arrival of the main solar energetic particle (SEP) event at Earth, both LETs observed a sudden burst of 1.6 to 15 MeV energetic neutral hydrogen atoms produced by either flare or shock-accelerated protons. RHESSI measurements of the 2.2-MeV gamma-ray line provide an estimate of the number of interacting flare-accelerated protons in this event, which leads to an improved estimate of ENA production by flare-accelerated protons. Taking into account ENA losses, we find that the observed ENAs must have been produced in the high corona at heliocentric distances > or equal to 2 solar radii. Although there are no CME images from this event, it is shown that CME-shock-accelerated protons can, in principle, produce a time-history consistent with the observations.

  6. Main reaction process simulation of hydrogen gas discharge in a ...

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... ... reactions of hydrogen discharge in small electric vacuum components at low pressure and weak ionization were confirmed. Among the 21 types of reactions in hydrogen discharge process, 11 of them play importnat roles under low pressure and weak ionization in cold cathode electric vacuum device.

  7. Precision spectroscopy of the 2S-4P{sub 1/2} transition in atomic hydrogen on a cold thermal beam of optically excited 2S atoms

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Axel; Kolachevsky, Nikolai; Alnis, Janis; Yost, Dylan C.; Matveev, Arthur; Parthey, Christian G.; Pohl, Randolf; Udem, Thomas [Max-Planck-Institut fuer Quantenoptik, 85748 Garching (Germany); Khabarova, Ksenia [FSUE ' VNIIFTRI' , 141570 Moscow (Russian Federation); Haensch, Theodor W. [Max-Planck-Institut fuer Quantenoptik, 85748 Garching (Germany); Ludwig-Maximilians-Universitaet, 80799 Muenchen (Germany)

    2013-07-01

    The 'proton size puzzle', i.e. the discrepancy between the values for the proton r.m.s. charge radius deduced from precision spectroscopy of atomic hydrogen and electron-proton-scattering on one side and the value deduced from muonic hydrogen spectroscopy on the other side, has been persisting for more than two years now. Although huge efforts have been put into trying to resolve this discrepancy from experimental and theoretical side, no convincing argument could be found so far. In this talk, we report on a unique precision spectroscopy experiment on atomic hydrogen, which is aiming to bring some light to the hydrogen part of the puzzle: In contrast to any previous high resolution experiment probing a transition frequency between the meta-stable 2S state and a higher lying nL state (n=3,4,6,8,12, L=S,P,D), our measurement of the 2S-4P{sub 1/2} transition frequency is the first experiment being performed on a cold thermal beam of hydrogen atoms optically excited to the 2S state. We will discuss how this helps to efficiently suppresses leading systematic effects of previous measurements and present the preliminary results we obtained so far.

  8. Incorporating nitrogen atoms into cobalt nanosheets as a strategy to boost catalytic activity toward CO2 hydrogenation

    Science.gov (United States)

    Wang, Liangbing; Zhang, Wenbo; Zheng, Xusheng; Chen, Yizhen; Wu, Wenlong; Qiu, Jianxiang; Zhao, Xiangchen; Zhao, Xiao; Dai, Yizhou; Zeng, Jie

    2017-11-01

    Hydrogenation of CO2 into fuels and useful chemicals could help to reduce reliance on fossil fuels. Although great progress has been made over the past decades to improve the activity of catalysts for CO2 hydrogenation, more efficient catalysts, especially those based on non-noble metals, are desired. Here we incorporate N atoms into Co nanosheets to boost the catalytic activity toward CO2 hydrogenation. For the hydrogenation of CO2, Co4N nanosheets exhibited a turnover frequency of 25.6 h-1 in a slurry reactor under 32 bar pressure at 150 °C, which was 64 times that of Co nanosheets. The activation energy for Co4N nanosheets was 43.3 kJ mol-1, less than half of that for Co nanosheets. Mechanistic studies revealed that Co4N nanosheets were reconstructed into Co4NHx, wherein the amido-hydrogen atoms directly interacted with the CO2 to form HCOO* intermediates. In addition, the adsorbed H2O* activated amido-hydrogen atoms via the interaction of hydrogen bonds.

  9. Giant Gas Cloud Made of Atoms Formed in First Stars Revealed in Universe's Most Distant Quasar

    Science.gov (United States)

    2003-07-01

    Astronomers studying the most distant quasar yet found in the Universe have discovered a massive reservoir of gas containing atoms made in the cores of some of the first stars ever formed. The carbon-monoxide gas was revealed by the National Science Foundation's Very Large Array (VLA) and the Plateau de Bure radio interferometer in Europe. The gas, along with the young galaxy containing it, is seen as it was when the Universe was only one-sixteenth its current age, just emerging from the primeval "Dark Ages" before light could travel freely through the cosmos. VLA Image of Quasar VLA Image of J1148+5251 CREDIT: NRAO/AUI/NSF (Click on Image for Larger Version) "Our discovery of this much carbon monoxide gas in such an extremely distant and young galaxy is surprising. It means that, even at a very early time in the history of the Universe, galaxies already had huge amounts of molecular gas that would eventually form new generations of stars," said Chris Carilli, of the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico. The distant galaxy, dubbed J1148+5251, contains a bright quasar powered by a black hole at least a billion times more massive than the Sun. The galaxy is seen as it was only 870 million years after the Big Bang. The Universe now is 13.7 billion years old. J1148+5251 would have been among the first luminous objects in the Universe. The original atoms formed in the Universe within the first three minutes of the Big Bang were only hydrogen and helium. Carbon and oxygen -- the atoms making up carbon monoxide -- had to be made in the thermonuclear furnaces at the cores of the earliest stars. "The carbon and oxygen atoms in the gas we detected were made by some of the first stars ever formed, only about 650 million years after the Big Bang. In the next 200 million years or so, those stars -- probably very different stars from those we see today -- exploded as supernovae, spreading the carbon and oxygen out into space. Those atoms then cooled

  10. A simulation code treating all twelve isotopic species of hydrogen gas and water for multistage chemical exchange column

    Energy Technology Data Exchange (ETDEWEB)

    Yamanishi, Toshihiko; Okuno, Kenji [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    1994-12-01

    A simulation code of the multistage chemical exchange column has been developed. The column has an electrolysis cell, a section for the liquid phase catalytic exchange, and a recombiner. The sieve trays and the catalyst beds are separated in the section for the liquid-vapor scrubbing steps and for the vapor-hydrogen gas exchange steps. This type of column is a promising system for the tritiated water processing. The code can deal with all the twelve molecular species of the hydrogen gas and the water. The equilibrium of atomic elements of H, D and T is also considered in the liquid phase. The Murphree-type factors are introduced in the code to evaluate the efficiencies for the sieve trays and catalyst beds. The solution of basic equations can be found out by the Newton-Raphson method. The atom fractions of D and T on the scrubbing trays are the independent variables of the equations: The order of the Jacobian matrix is only twice the number of sieve trays. The solution of the basic equations could be obtained for several example cases; and no difficulty was observed for the convergence of the calculations. Broyden`s method was quite effective to reduce computation time of the code. (author).

  11. 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.

  12. 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...

  13. Concerted hydrogen atom and electron transfer mechanism for catalysis by lysine-specific demethylase.

    Science.gov (United States)

    Yu, Tao; Higashi, Masahiro; Cembran, Alessandro; Gao, Jiali; Truhlar, Donald G

    2013-07-18

    We calculate the free energy profile for the postulated hydride transfer reaction mechanism for the catalysis of lysine demethylation by lysine-specific demethylase LSD1. The potential energy surface is obtained by using combined electrostatically embedded multiconfiguration molecular mechanics (EE-MCMM) and single-configuration molecular mechanics (MM). We employ a constant valence bond coupling term to obtain analytical energies and gradients of the EE-MCMM subsystem, which contains 45 quantum mechanics (QM) atoms and which is parametrized with density functional calculations employing specific reaction parameters obtained by matching high-level wave function calculations. In the MM region, we employ the Amber ff03 and TIP3P force fields. The free energy of activation at 300 K is calculated by molecular dynamics (MD) umbrella sampling on a system with 102,090 atoms as the maximum of the free energy profile along the reaction coordinate as obtained by the weighted histogram analysis method with 17 umbrella sampling windows. This yields a free energy of activation of only 10 kcal/mol, showing that the previously postulated direct hydride transfer reaction mechanism is plausible, although we find that it is better interpreted as a concerted transfer of a hydrogen atom and an electron.

  14. Research on Sources of Gas Phase Metastable Atoms and Molecules

    Science.gov (United States)

    1982-05-01

    reported in a post-deadline paper at thu Paris ICPEAC Conference (35) which described an experimental measurement of electron impact excitiation cross...are completely removed from the plate resulting in a positive cur- rent monitored by a high sensitivity electrometer. Ihe guard plates insure that...physics of high-power lasers (e.g., the rare gas- halides ). Unfortunately, even the lowest of the metastable rare gas en- ergy levels, the Xe*( 3P0) with

  15. "Additive" cooperativity of hydrogen bonds in complexes of catechol with proton acceptors in the gas phase: FTIR spectroscopy and quantum chemical calculations.

    Science.gov (United States)

    Varfolomeev, Mikhail A; Klimovitskii, Alexander E; Abaidullina, Dilyara I; Madzhidov, Timur I; Solomonov, Boris N

    2012-06-01

    Experimental study of hydrogen bond cooperativity in hetero-complexes in the gas phase was carried out by IR-spectroscopy method. Stretching vibration frequencies of O-H groups in phenol and catechol molecules as well as of their complexes with nitriles and ethers were determined in the gas phase using a specially designed cell. O-H groups experimental frequency shifts in the complexes of catechol induced by the formation of intermolecular hydrogen bonds are significantly higher than in the complexes of phenol due to the hydrogen bond cooperativity. It was shown that the cooperativity factors of hydrogen bonds in the complexes of catechol with nitriles and ethers in the gas phase are approximately the same. Quantum chemical calculations of the studied systems have been performed using density functional theory (DFT) methods. It was shown, that theoretically obtained cooperativity factors of hydrogen bonds in the complexes of catechol with proton acceptors are in good agreement with experimental values. Cooperative effects lead to a strengthening of intermolecular hydrogen bonds in the complexes of catechol on about 30%, despite the significant difference in the proton acceptor ability of the bases. The analysis within quantum theory of atoms in molecules was carried out for the explanation of this fact. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Empirical Method to Estimate Hydrogen Embrittlement of Metals as a Function of Hydrogen Gas Pressure at Constant Temperature

    Science.gov (United States)

    Lee, Jonathan A.

    2010-01-01

    High pressure Hydrogen (H) gas has been known to have a deleterious effect on the mechanical properties of certain metals, particularly, the notched tensile strength, fracture toughness and ductility. The ratio of these properties in Hydrogen as compared to Helium or Air is called the Hydrogen Environment Embrittlement (HEE) Index, which is a useful method to classify the severity of H embrittlement and to aid in the material screening and selection for safety usage H gas environment. A comprehensive world-wide database compilation, in the past 50 years, has shown that the HEE index is mostly collected at two conveniently high H pressure points of 5 ksi and 10 ksi near room temperature. Since H embrittlement is directly related to pressure, the lack of HEE index at other pressure points has posed a technical problem for the designers to select appropriate materials at a specific H pressure for various applications in aerospace, alternate and renewable energy sectors for an emerging hydrogen economy. Based on the Power-Law mathematical relationship, an empirical method to accurately predict the HEE index, as a function of H pressure at constant temperature, is presented with a brief review on Sievert's law for gas-metal absorption.

  17. Measurement of the Rate of Muon Capture in Hydrogen Gas and Determination of the Proton's Pseudoscalar Coupling $g_P$

    CERN Document Server

    Andreev, V A; Case, T A; Chitwood, D B; Clayton, S M; Crowe, K M; Deutsch, J; Egger, J; Freedman, S J; Ganzha, V A; Gorringe, T; Gray, F E; Hertzog, D W; Hildebrandt, M; Kammel, P; Kiburg, B; Knaack, S; Kravtsov, P A; Krivshich, A G; Lauss, B; Lynch, K L; Maev, E M; Maev, O E; Mulhauser, F; Özben, C S; Petitjean, C; Petrov, G E; Prieels, R; Schapkin, G N; Semenchuk, G G; Soroka, M A; Tishchenko, V; Vasilyev, A A; Vorobyov, A A; Vznuzdaev, M E; Winter, P

    2007-01-01

    The rate of nuclear muon capture by the proton has been measured using a new experimental technique based on a time projection chamber operating in ultra-clean, deuterium-depleted hydrogen gas at 1 MPa pressure. The capture rate was obtained from the difference between the measured $\\mu^-$ disappearance rate in hydrogen and the world average for the $\\mu^+$ decay rate. The target's low gas density of 1% compared to liquid hydrogen is key to avoiding uncertainties that arise from the formation of muonic molecules. The capture rate from the hyperfine singlet ground state of the $\\mu p$ atom is measured to be $\\Lambda_S=725.0 \\pm 17.4 s^{-1}$, from which the induced pseudoscalar coupling of the nucleon, $g_P(q^2=-0.88 m_\\mu^2)=7.3 \\pm 1.1$, is extracted. This result is consistent with theoretical predictions for $g_P$ that are based on the approximate chiral symmetry of QCD.

  18. Hydrogen gas filling into an actual tank at high pressure and optimization of its thermal characteristics

    Science.gov (United States)

    Khan, Md. Tawhidul Islam; Monde, Masanori; Setoguchi, Toshiaki

    2009-09-01

    Gas with high pressure is widely used at present as fuel storage mode for different hydrogen vehicles. Different types of materials are used for constructing these hydrogen pressure vessels. An aluminum lined vessel and typically carbon fiber reinforced plastic (CFRP) materials are commercially used in hydrogen vessels. An aluminum lined vessel is easy to construct and posses high thermal conductivity compared to other commercially available vessels. However, compared to CFRP lined vessel, it has low strength capacity and safety factors. Therefore, nowadays, CFRP lined vessels are becoming more popular in hydrogen vehicles. Moreover, CFRP lined vessel has an advantage of light weight. CFRP, although, has many desirable properties in reducing the weight and in increasing the strength, it is also necessary to keep the material temperature below 85 °C for maintaining stringent safety requirements. While filling process occurs, the temperature can be exceeded due to the compression works of the gas flow. Therefore, it is very important to optimize the hydrogen filling system to avoid the crossing of the critical limit of the temperature rise. Computer-aided simulation has been conducted to characterize the hydrogen filling to optimize the technique. Three types of hydrogen vessels with different volumes have been analyzed for optimizing the charging characteristics of hydrogen to test vessels. Gas temperatures are measured inside representative vessels in the supply reservoirs (H2 storages) and at the inlet to the test tank during filling.

  19. The Influence of Hydrogen Gas on the Measures of Efficiency of Diesel Internal Combustion Engine

    Directory of Open Access Journals (Sweden)

    Jurgis Latakas

    2014-12-01

    Full Text Available In this research paper energy and ecological parameters of diesel engine which works under addition of hydrogen (10, 20, 30 l/ min are presented. A survey of research literature has shown that addition of hydrogen gases improve diesel combustion; increase indicated pressure; decrease concentration of carbon dioxide (CO2, hydrocarbons (HC, particles; decrease fuel consumptions. Results of the experiment revealed that hydrogen gas additive decreased pressure in cylinder in kinetic combustion phase. Concentration of CO2 and nitrous oxides (NOx decreased not significantly, HC – increased. Concentration of particles in engine exhaust gases significantly decreased. In case when hydrogen gas as additive was supplied, the fuel consumptions decreased a little. Using AVL BOOST software combustion process analysis was made. It was determined that in order to optimize engine work process under hydrogen additive usage, it is necessary to adjust diesel injection angle.

  20. Influence of Pt Gate Electrode Thickness on the Hydrogen Gas Sensing Characteristics of Pt/In2O3/SiC Hetero-Junction Devices

    Directory of Open Access Journals (Sweden)

    S. Kandasamy

    2007-09-01

    Full Text Available Hetero-junction Pt/In2O3/SiC devices with different Pt thickness (30, 50 and 90nm were fabricated and their hydrogen gas sensing characteristics have been studied. Pt and In2O3 thin films were deposited by laser ablation. The hydrogen sensitivity was found to increase with decreasing Pt electrode thickness. For devices with Pt thickness of 30 nm, the sensitivity gradually increased with increasing temperature and reached a maximum of 390 mV for 1% hydrogen in air at 530°C. Atomic force microscopy (AFM analysis revealed a decrease in Pt grain size and surface roughness for increasing Pt thickness. The relationship between the gas sensing performance and the Pt film thickness and surface morphology is discussed.

  1. Direct chlorination process for geothermal power plant off-gas - hydrogen sulfide abatement

    Energy Technology Data Exchange (ETDEWEB)

    Sims, A.V.

    1983-06-01

    The Direct Chlorination Process removes hydrogen sulfide from geothermal off-gases by reacting hydrogen sulfide with chlorine in the gas phase. Hydrogen chloride and elemental sulfur are formed by this reaction. The Direct Chlorination Process has been successfully demonstrated by an on-site operation of a pilot plant at the 3 M We HPG-A geothermal power plant in the Puna District on the island of Hawaii. Over 99.5 percent hydrogen sulfide removal was achieved in a single reaction stage. Chlorine gas did not escape the pilot plant, even when 90 percent excess chlorine gas was used. Because of the higher cost of chemicals and the restricted markets in Hawaii, the economic viability of this process in Hawaii is questionable.

  2. Direct chlorination process for geothermal power plant off-gas - hydrogen sulfide abatement

    Energy Technology Data Exchange (ETDEWEB)

    Sims, A.V.

    1983-06-01

    The Direct Chlorination Process removes hydrogen sulfide from geothermal off-gases by reacting hydrogen sulfide with chlorine in the gas phase. Hydrogen chloride and elemental sulfur are formed by this reaction. The Direct Chlorination Process has been successfully demonstrated by an on-site operation of a pilot plant at the 3 M We HPG-A geothermal power plant in the Puna District on the island of Hawaii. Over 99.5 percent hydrogen sulfide removal was achieved in a single reaction state. Chlorine gas did not escape the pilot plant, even when 90 percent excess chlorine gas was used. A preliminary economic evaluation of the Direct Chlorination Process indicates that it is very competitive with the Stretford Process. Compared to the Stretford Process, the Direct Chlorination Process requires about one-third the initial capital investment and about one-fourth the net daily expenditure.

  3. Hydrogen transfer on USY zeolites during gas oil cracking: Influence of the adsorption characteristics of the zeolite catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Corma, A.; Faraldos, M.; Martinez, A.; Mifsud, A. (CSIC, Madrid (Spain))

    1990-04-01

    In this work, the hydrogen transfer activity of two series of HY zeolites dealuminated by steam and by SiCl{sub 4} (24.47-24.24 {angstrom} unit cell) has been measured from the butene/butane ratio in the products obtained during the cracking of a vacuum gas oil at 756 K. With the steam-dealuminated zeolites, a sharp decrease in the ratio of hydrogen transfer to cracking is observed when the number of Al atoms per unit cell falls below 10. On the other hand, in samples dealuminated by SiCl{sub 4}, this ratio changes very little with dealumination. These results cannot be explained assuming the need for adjacent acid sites for the hydrogen transfer. The authors have found, by adsorption measurements of n-butane and 1-butene, that the changes in the relative rates of bimolecular (hydrogen transfer) to monomolecular (cracking) reactions, observed with dealuminated HY zeolites, can be explained by the changes in the adsorption capacity and adsorption selectivity which occur on zeolites dealuminated at different levels by different dealumination procedures, and which are due to changes in the electric fields inside the pores.

  4. Performance of a Small Gas Generator Using Liquid Hydrogen and Liquid Oxygen

    Science.gov (United States)

    Acker, Loren W.; Fenn, David B.; Dietrich, Marshall W.

    1961-01-01

    The performance and operating problems of a small hot-gas generator burning liquid hydrogen with liquid oxygen are presented. Two methods of ignition are discussed. Injector and combustion chamber design details based on rocket design criteria are also given. A carefully fabricated showerhead injector of simple design provided a gas generator that yielded combustion efficiencies of 93 and 96 percent.

  5. Geochemical modelling of hydrogen gas migration in an unsaturated bentonite buffer

    NARCIS (Netherlands)

    Sedighi, M.; Thomas, H.R.; Al Masum, S.; Vardon, P.J.; Nicholson, D.; Chen, Q.

    2014-01-01

    This paper presents an investigation of the transport and fate of hydrogen gas through compacted bentonite buffer. Various geochemical reactions that may occur in the multiphase and multicomponent system of the unsaturated bentonite buffer are considered. A reactive gas transport model, developed

  6. CHOOSING OF PERFORMANCE PARAMETERS OF LIGHT-DUTY ENGINE RUNNING ON NATURAL GAS AND HYDROGEN MIXTURE

    Directory of Open Access Journals (Sweden)

    Y. Dube

    2011-01-01

    Full Text Available The results of investigation of light-duty gas engine running on natural gas and hydrogen mixture has been given. The mathematical model of combustion process with variable Vibe combus-tion factor for this engine type has been specified.

  7. Development and industrial application of catalyzer for low-temperature hydrogenation hydrolysis of Claus tail gas

    Directory of Open Access Journals (Sweden)

    Honggang Chang

    2015-10-01

    Full Text Available With the implementation of more strict national environmental protection laws, energy conservation, emission reduction and clean production will present higher requirements for sulfur recovery tail gas processing techniques and catalyzers. As for Claus tail gas, conventional hydrogenation catalyzers are gradually being replaced by low-temperature hydrogenation catalyzers. This paper concentrates on the development of technologies for low-temperature hydrogenation hydrolysis catalyzers, preparation of such catalyzers and their industrial application. In view of the specific features of SO2 hydrogenation and organic sulfur hydrolysis during low-temperature hydrogenation, a new technical process involving joint application of hydrogenation catalyzers and hydrolysis catalyzers was proposed. In addition, low-temperature hydrogenation catalyzers and low-temperature hydrolysis catalyzers suitable for low-temperature conditions were developed. Joint application of these two kinds of catalyzers may reduce the inlet temperatures in the conventional hydrogenation reactors from 280 °C to 220 °C, at the same time, hydrogenation conversion rates of SO2 can be enhanced to over 99%. To further accelerate the hydrolysis rate of organic sulfur, the catalyzers for hydrolysis of low-temperature organic sulfur were developed. In lab tests, the volume ratio of the total sulfur content in tail gas can be as low as 131 × 10−6 when these two kinds of catalyzers were used in a proportion of 5:5 in volumes. Industrial application of these catalyzers was implemented in 17 sulfur recovery tail gas processing facilities of 15 companies. As a result, Sinopec Jinling Petrochemical Company had outstanding application performances with a tail gas discharging rate lower than 77.9 mg/m3 and a total sulfur recovery of 99.97%.

  8. Hydrogen gas reduces hyperoxic lung injury via the Nrf2 pathway in vivo

    Science.gov (United States)

    Kawamura, Tomohiro; Wakabayashi, Nobunao; Shigemura, Norihisa; Huang, Chien-Sheng; Masutani, Kosuke; Tanaka, Yugo; Noda, Kentaro; Peng, Ximei; Takahashi, Toru; Billiar, Timothy R.; Okumura, Meinoshin; Toyoda, Yoshiya; Kensler, Thomas W.

    2013-01-01

    Hyperoxic lung injury is a major concern in critically ill patients who receive high concentrations of oxygen to treat lung diseases. Successful abrogation of hyperoxic lung injury would have a huge impact on respiratory and critical care medicine. Hydrogen can be administered as a therapeutic medical gas. We recently demonstrated that inhaled hydrogen reduced transplant-induced lung injury and induced heme oxygenase (HO)-1. To determine whether hydrogen could reduce hyperoxic lung injury and investigate the underlying mechanisms, we randomly assigned rats to four experimental groups and administered the following gas mixtures for 60 h: 98% oxygen (hyperoxia), 2% nitrogen; 98% oxygen (hyperoxia), 2% hydrogen; 98% balanced air (normoxia), 2% nitrogen; and 98% balanced air (normoxia), 2% hydrogen. We examined lung function by blood gas analysis, extent of lung injury, and expression of HO-1. We also investigated the role of NF-E2-related factor (Nrf) 2, which regulates HO-1 expression, by examining the expression of Nrf2-dependent genes and the ability of hydrogen to reduce hyperoxic lung injury in Nrf2-deficient mice. Hydrogen treatment during exposure to hyperoxia significantly improved blood oxygenation, reduced inflammatory events, and induced HO-1 expression. Hydrogen did not mitigate hyperoxic lung injury or induce HO-1 in Nrf2-deficient mice. These findings indicate that hydrogen gas can ameliorate hyperoxic lung injury through induction of Nrf2-dependent genes, such as HO-1. The findings suggest a potentially novel and applicable solution to hyperoxic lung injury and provide new insight into the molecular mechanisms and actions of hydrogen. PMID:23475767

  9. Probing an atomic gas confined in a nanocell

    Energy Technology Data Exchange (ETDEWEB)

    Maurin, I; Todorov, P; Hamdi, I; Yarovitski, A; Dutier, G; Sarkisyan, D; Saltiel, S; Gorza, M-P; Fichet, M; Bloch, D; Ducloy, M [Laboratoire de Physique des Lasers, UMR 7538 du CNRS et de l' Universite Paris 13, 99 Av JB Clement, F-93430 Villetaneuse (France)

    2005-01-01

    Since the recent realization of extremely thin vapour cells (local thickness: 20-1000 nm), we investigate the optical properties of these 1-D confined vapours. Aside from their interest for Doppler-free spectroscopy, nanocells offer a new tool to evaluate collisional shift and broadening, yielding an access to the open problem of collisions under confinement. It also allows probing of the atom-surface interaction in a range of unusual short distances. The experimental exploration of the distance dependence, normally evolving according to the z{sup -3} van der Waals (vW) dependence (z : the atom-surface distance), is worth doing because it could be affected by imperfections of the real surface, such as roughness, adsorbed impurities or charges. A detailed lineshape analysis is now under progress, with tight constraints imposed to the fitting by the twin information brought by simultaneous reflection and transmission spectra. Another issue is a possible resonant enhancement, susceptible to induce a repulsive vW, due to the coupling between atom excitation and a surface mode.

  10. 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.

  11. Catalytic activity of Pd-doped Cu nanoparticles for hydrogenation as a single-atom-alloy catalyst.

    Science.gov (United States)

    Cao, Xinrui; Fu, Qiang; Luo, Yi

    2014-05-14

    The single atom alloy of extended surfaces is known to provide remarkably enhanced catalytic performance toward heterogeneous hydrogenation. Here we demonstrate from first principles calculations that this approach can be extended to nanostructures, such as bimetallic nanoparticles. The catalytic properties of the single-Pd-doped Cu55 nanoparticles have been systemically examined for H2 dissociation as well as H atom adsorption and diffusion, following the concept of single atom alloy. It is found that doping a single Pd atom at the edge site of the Cu55 shell can considerably reduce the activation energy of H2 dissociation, while the single Pd atom doped at the top site or in the inner layers is much less effective. The H atom adsorption on Cu55 is slightly stronger than that on the Cu(111) surface; however, a larger nanoparticle that contains 147 atoms could effectively recover the weak binding of the H atoms. We have also investigated the H atom diffusion on the 55-atom nanoparticle and found that spillover of the produced H atoms could be a feasible process due to the low diffusion barriers. Our results have demonstrated that facile H2 dissociation and weak H atom adsorption could be combined at the nanoscale. Moreover, the effects of doping one more Pd atom on the H2 dissociation and H atom adsorption have also been investigated. We have found that both the doping Pd atoms in the most stable configuration could independently exhibit their catalytic activity, behaving as two single-atom-alloy catalysts.

  12. Magnetic resonance lineshape of atomic hydrogen on liquid helium surfaces. The sticking probability of H on /sup 4/He and /sup 3/He

    Energy Technology Data Exchange (ETDEWEB)

    Berlinsky, A.J.; Morrow, M.; Jochemsen, R.; Hardy, W.N. (British Columbia Univ., Vancouver (Canada). Dept. of Physics)

    1982-07-01

    High resolution magnetic resonance studies of the 1420 MHz transition in atomic hydrogen confined in a liquid helium coated container have been performed at temperatures 0.06atoms on the liquid helium surface, by the exchange rate between atoms in the gas and atoms on the surface, and by the hyperfine frequency shift of an H atom in the bound surface state. Using a model with a Poisson distribution for the residency times, it is possible to interpret both the hyperfine frequency shift and the width of the resonance line as a function of temperature for H on /sup 4/He. The analysis gives the binding energy, the frequency in the surface state, and the sticking probability ..cap alpha.. for H on /sup 4/He. We obtain ..cap alpha..=0.035+-0.004. The results for H on /sup 3/He are more complicated, and possible explanations are discussed.

  13. Hydrogen.

    Science.gov (United States)

    Bockris, John O'M

    2011-11-30

    The idea of a "Hydrogen Economy" is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO₂ in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H₂ from the electrolyzer. Methanol made with CO₂ from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan). Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs) by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  14. A comprehensive study on atomic layer deposition of molybdenum sulfide for electrochemical hydrogen evolution

    Science.gov (United States)

    Kwon, Do Hyun; Jin, Zhenyu; Shin, Seokhee; Lee, Wook-Seong; Min, Yo-Sep

    2016-03-01

    Atomic layer deposition (ALD) has emerged as an efficient method to design and prepare catalysts with atomic precision. Here, we report a comprehensive study on ALD of molybdenum sulfide (MoSx) for an electrocatalytic hydrogen evolution reaction. By using molybdenum hexacarbonyl and dimethyldisulfide as the precursors of Mo and S, respectively, the MoSx catalysts are grown at 100 °C on porous carbon fiber papers (CFPs). The ALD process results in the growth of particle-like MoSx on the CFP due to the lack of adsorption sites, and its crystallographic structure is a mixture of amorphous and nano-crystalline phases. In order to unveil the intrinsic activity of the ALD-MoSx, the exchange current densities, Tafel slopes, and turnover frequencies of the catalysts grown under various ALD conditions have been investigated by considering the fractional surface coverage of MoSx on the CFP and catalytically-active surface area. In addition, the ALD-MoSx/CFP catalysts exhibit excellent catalytic stability due to the strong adhesion of MoSx on the CFP and the mixed phase.Atomic layer deposition (ALD) has emerged as an efficient method to design and prepare catalysts with atomic precision. Here, we report a comprehensive study on ALD of molybdenum sulfide (MoSx) for an electrocatalytic hydrogen evolution reaction. By using molybdenum hexacarbonyl and dimethyldisulfide as the precursors of Mo and S, respectively, the MoSx catalysts are grown at 100 °C on porous carbon fiber papers (CFPs). The ALD process results in the growth of particle-like MoSx on the CFP due to the lack of adsorption sites, and its crystallographic structure is a mixture of amorphous and nano-crystalline phases. In order to unveil the intrinsic activity of the ALD-MoSx, the exchange current densities, Tafel slopes, and turnover frequencies of the catalysts grown under various ALD conditions have been investigated by considering the fractional surface coverage of MoSx on the CFP and catalytically

  15. Atomic Gas Distribution in HCG31 and HCG92

    Science.gov (United States)

    Borthakur, Sanchayeeta; Yun, M.; Verdes-Montenegro, L.; Heckman, T. M.; Zhu, G.

    2014-01-01

    We present Green Bank Telescope (GBT) 5x5 grid observations surrounding the actively star forming groups Hickson Compact Group, HCG 31 and HCG 92. We find that the total HI content of the groups are 2x10^10 and 2.5x10^10 solar masses respectively. The HI in HCG31 is mostly associated with the central region, however, there is a faint extension of the order of 10^9 solar masses of gas toward the southeast direction detected at the GBT pointing centered at a distance of 185 kpc from the group center. The velocity range of the HI is similar to the HI in the central pixel indicating its kinematic link to the gas in the center of the group. HCG 92 shows strong HI emission at a position of a pointing 4' offset from the center. The ``HI-wing" at velocities 6350-6500 km/s (Borthakur et al. 2010) were found to be confined to a few pointings adjacent to the peak suggesting that the wing as is localized and not extended. However, this must be gas stripped due to interactions and are dynamically connected to the Arc-N (Williams et al. 2002). We comment on the survival of the gas from the ionizing photons of the metagalactic ultraviolet background and those produced by the starburst. The implication of the existence of an HI rich environments surrounding the starbursts support the possibility of continued and future star formation in these groups.

  16. Monolithic Laser Scribed Graphene Scaffold with Atomic Layer Deposited Platinum for Hydrogen Evolution Reaction

    KAUST Repository

    Nayak, Pranati

    2017-09-01

    The use of three-dimensional (3D) electrode architectures as scaffolds for conformal deposition of catalysts is an emerging research area with significant potential for electrocatalytic applications. In this study, we report the fabrication of monolithic, self-standing, 3D graphitic carbon scaffold with conformally deposited Pt by atomic layer deposition (ALD) as a hydrogen evolution reaction catalyst. Laser scribing is employed to transform polyimide into 3D porous graphitic carbon, which possesses good electronic conductivity and numerous edge plane sites. This laser scribed graphene (LSG) architecture makes it possible to fabricate monolithic electrocatalyst support without any binders or conductive additives. The synergistic effect between ALD of Pt on 3D network of LSG provides an avenue for minimal yet effective Pt usage, leading to an enhanced HER activity. This strategy establish a general approach for inexpensive and large scale HER device fabrication with minimum catalyst cost.

  17. Rovibrational excitation of HD in collisions with atomic and molecular hydrogen

    Science.gov (United States)

    Flower, D. R.; Roueff, E.

    1999-11-01

    We have computed cross-sections and rate coefficients for rovibrational transitions in HD, induced by collisions with atomic and molecular hydrogen. We employed fully quantum-mechanical methods and the potential of Boothroyd et al. for H-HD, and that of Schwenke for H2-HD. The rate coefficients for vibrational relaxation v=1->0 of HD are compared with the corresponding values for H2. The influence of vibrationally excited channels on the rate coefficients for rotational transitions within the v=0 vibrational ground state of HD is shown to be small at T=500K, where T is the kinetic temperature. The rate coefficients, for 100http://ccp7.dur.ac.uk/.

  18. The Quantum Black Hole as a Hydrogen Atom: Microstates Without Strings Attached

    CERN Document Server

    Hooft, Gerard t

    2016-01-01

    Applying an expansion in spherical harmonics, turns the black hole with its microstates into something about as transparent as the hydrogen atom was in the early days of quantum mechanics. It enables us to present a concise description of the evolution laws of these microstates, linking them to perturbative quantum field theory, in the background of the Schwarzschild metric. Three pieces of insight are obtained: One, we learn how the gravitational back reaction, whose dominant component can be calculated exactly, turns particles entering the hole, into particles leaving it, by exchanging the momentum- and position operators; two, we find out how this effect removes firewalls, both on the future and the past event horizon, and three, we discover that the presence of region II in the Penrose diagram forces a topological twist in the background metric, culminating in antipodal identification. Although a cut-off is required that effectively replaces the transverse coordinates by a lattice, the effect of such a cu...

  19. High precision X-ray spectroscopy in hydrogen-like fermionic and bosonic atomic systems

    Energy Technology Data Exchange (ETDEWEB)

    Borchert, G.L.; Anagnostopoulos, D.; Augsburger, M.; Belmiloud, D.; Castelli, C.; Chatellard, D.; Daum, M.; Egger, J.P.; El-Khoury, P.; Elble, M.; Frosch, R.; Gorke, H.; Gotta, D.; Hauser, P.; Indelicato, P.; Kirch, K.; Lenz, S.; Nelms, N.; Rashid, K.; Schult, O.W.B. (and others)

    1998-11-15

    Some time after its formation an exotic atom may be considered a hydrogen-like system consisting of a nucleus and an exotic particle in a bound state. In this situation it is an ideal tool to study cascade properties, while for the innermost orbits it can be used to probe the interaction with the nucleus. From an extended series of experiments using high resolution X-ray spectroscopy for both aspects typical examples are reported and preliminary results are given: 1. To determine the complex scattering length in p-barH the 3D{yields}2P hyperfine transitions have been measured. 2. To determine the pion mass the 5 {yields} 4 transitions in {pi}{sup 14}N have been studied. In all cases a major contribution to the uncertainty originates from the calibration. Therefore a new method is proposed that will establish a universal set of high precision calibration lines for pionic, muonic and electronic systems.

  20. Life cycle greenhouse emissions of compressed natural gas-hydrogen mixtures for transportation in Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, P. [Instituto de Energia y Desarrollo Sustentable, CNEA, CONICET, Av. del Libertador 8250, Ciudad Autonoma de Buenos Aires (Argentina); Dawidowski, L.; Gomez, D. [Gerencia Quimica, CNEA, Av. Gral. Paz 1499, San Martin (Argentina); Pasquevich, D. [Instituto de Energia y Desarrollo Sustentable, CNEA, CONICET, Av. del Libertador 8250, Ciudad Autonoma de Buenos Aires (Argentina); Centro Atomico Bariloche, CNEA, Av. Bustillo 9500, S.C. de Bariloche (Argentina)

    2010-06-15

    We have developed a model to assess the life cycle greenhouse emissions of compressed natural gas-hydrogen (CNG-H{sub 2}) mixtures used for transportation in Argentina. The overall fuel life cycle is assessed through a well-to-wheel (WTW) analysis for different hydrogen generation and distribution options. The combustion stage in road vehicles is modeled using the COPERT IV model. Hydrogen generation options include classical steam methane reforming (SMR) and water electrolysis (WE) in central plants and distributed facilities at the refueling stations. Centralized hydrogen generation by electrolysis in nuclear plants as well as the use of solar photovoltaic and wind electricity is also considered. Hydrogen distribution options include gas pipeline and refrigerated truck transportation for liquefied hydrogen. A total number of fifteen fuel pathways are studied; in all the cases the natural gas-hydrogen mixture is made at the refueling station. The use of WE using nuclear or wind electricity appears to be less contaminant that the use of pure CNG. (author)

  1. Multi-Walled Carbon Nanotube-Doped Tungsten Oxide Thin Films for Hydrogen Gas Sensing

    Directory of Open Access Journals (Sweden)

    Adisorn Tuantranont

    2010-08-01

    Full Text Available In this work we have fabricated hydrogen gas sensors based on undoped and 1 wt% multi-walled carbon nanotube (MWCNT-doped tungsten oxide (WO3 thin films by means of the powder mixing and electron beam (E-beam evaporation technique. Hydrogen sensing properties of the thin films have been investigated at different operating temperatures and gas concentrations ranging from 100 ppm to 50,000 ppm. The results indicate that the MWCNT-doped WO3 thin film exhibits high sensitivity and selectivity to hydrogen. Thus, MWCNT doping based on E-beam co-evaporation was shown to be an effective means of preparing hydrogen gas sensors with enhanced sensing and reduced operating temperatures. Creation of nanochannels and formation of p-n heterojunctions were proposed as the sensing mechanism underlying the enhanced hydrogen sensitivity of this hybridized gas sensor. To our best knowledge, this is the first report on a MWCNT-doped WO3 hydrogen sensor prepared by the E-beam method.

  2. Exploring the thermodynamics of Bose-Einstein condensation in a homogeneous atomic gas

    Science.gov (United States)

    Schmidutz, Tobias; Gotlibovych, Igor; Gaunt, Alexander; Smith, Robert; Hadzibabic, Zoran

    2013-05-01

    Atomic Bose-Einstein condensates have traditionally been produced in harmonic traps and only very recently it became possible to attain condensation in a homogeneous gas [A.L. Gaunt et al., arXiv:1212.4453]. In this talk we will present our new experimental results on the thermodynamics of condensation in a homogeneous weakly interacting Bose gas. We perform a systematic study of the tuning of the critical temperature with system parameters, the saturation of the thermal components in a partially condensed sample, and the total energy of the gas. We also study the dynamics of cooling in a uniform gas.

  3. DISTRIBUTION OF FAINT ATOMIC GAS IN HICKSON COMPACT GROUPS

    Energy Technology Data Exchange (ETDEWEB)

    Borthakur, Sanchayeeta; Heckman, Timothy M.; Zhu, Guangtun [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Yun, Min Su [Astronomy Department, University of Massachusetts, Amherst, MA 01003 (United States); Verdes-Montenegro, Lourdes [Instituto de Astrofísica de Andalucía, CSIC, Apdo. Correos 3004, E-18080 Granada (Spain); Braatz, James A., E-mail: sanch@pha.jhu.edu [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)

    2015-10-10

    We present 21 cm H i observations of four Hickson Compact Groups (HCGs) 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′ × 25′ (140–650 kpc) surrounding each HCG, these observations provide better estimates of H i masses. In particular, we detected 65% more H i than that detected in the Karl G. Jansky Very Large Array (VLA) imaging of HCG 92. We also identify whether the diffuse gas has the same spatial distribution as the high surface brightness (HSB) H i features detected in the VLA maps of these groups by comparing the H i strengths between the observed and modeled masses based on VLA maps. We found that the H i observed with the GBT has a similar spatial distribution to the HSB structures in HCG 31 and HCG 68. Conversely, the observed H i distributions in HCG 44 and HCG 92 were extended and showed significant offsets from the modeled masses. Most of the faint gas in HCG 44 lies to the northeast–southwest region and in HCG 92 lies in the northwest region of their respective groups. The spatial and dynamical similarities between the total (faint+HSB) and the HSB H i indicate that the faint gas is of tidal origin. We found that the gas will survive ionization by the cosmic UV background and the escaping ionizing photons from the star-forming regions and stay primarily neutral for at least 500 Myr.

  4. Propagating of partially coherent laser beam in the near-resonant atomic gas

    Science.gov (United States)

    Kong, Delong; Wang, Zhaoying; Fang, Feiyun; Shi, Congquan; Lin, Qiang

    2017-09-01

    The characteristics of the light with various degrees of spatial coherence traveling in near-resonant atomic gas are investigated both experimentally and theoretically. The experimental results show that the coherence of partially coherent beams can get better after interaction with atoms under some certain conditions compared with that before interaction. The experimental results are explained theoretically by the method of spectroscopy absorption. Furthermore, partially coherent light has a better environmental adaptability than fully coherent light.

  5. The influence hydrogen atom addition has on charge switching during motion of the metal atom in endohedral Ca@C60H4 isomers

    Science.gov (United States)

    Raggi, G.; Besley, E.; Stace, A. J.

    2016-01-01

    Density functional theory has been applied in a study of charge transfer between an endohedral calcium atom and the fullerene cage in Ca@C60H4 and [Ca@C60H4]+ isomers. Previous calculations on Ca@C60 have shown that the motion of calcium within a fullerene is accompanied by large changes in electron density on the carbon cage. Based on this observation, it has been proposed that a tethered endohedral fullerene might form the bases of a nanoswitch. Through the addition of hydrogen atoms to one hemisphere of the cage it is shown that, when compared with Ca@C60, asymmetric and significantly reduced energy barriers can be generated with respect to motion of the calcium atom. It is proposed that hydrogen atom addition to a fullerene might offer a route for creating a bi-stable nanoswitch that can be fine-tuned through the selection of an appropriate isomer and number of atoms attached to the cage of an endohedral fullerene. This article is part of the themed issue ‘Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene’. PMID:27501967

  6. Selection rule engineering of forbidden transitions of a hydrogen atom near a nanogap

    Science.gov (United States)

    Kim, Hyunyoung Y.; Kim, Daisik S.

    2018-01-01

    We perform an analytical study on the allowance of forbidden transitions for a hydrogen atom placed near line dipole sources, mimicking light emanating from a one-dimensional metallic nanogap. It is shown that the rapid variation of the electric field vector, inevitable in the near zone, completely breaks the selection rule of Δl=±1. While the forbidden transitions between spherically symmetric S states, such as 2S to 1S or 3S to 1S (Δl=0), are rather robust against selection rule breakage, Δl=±2 transitions such as between 3D and 1S or 3D and 2S states are very vulnerable to the spatial variation of the perturbing electric field. Transitions between 2S and 3D states are enhanced by many orders of magnitude, aided by the quadratic nature of both the perturbing Hamiltonian and D wavefunctions. The forbidden dipole moment, which approaches one Bohr radius times the electric charge in the vicinity of the gap, can be written in a simple closed form owing to the one-dimensional nature of our gap. With large enough effective volume together with the symmetric nature of the excited state wavefunctions, our work paves way towards atomic physics application of infinitely long nanogaps.

  7. Observation and Interpretation of Energetic Neutral Hydrogen Atoms from the December 5, 2006 Solar Flare

    Science.gov (United States)

    Barghouty, A. F.; Mewaldt, R. A.; Leske, R. A.; Shih, A. Y.; Stone, E. C.; Cohen, C. M. S.; Cummings, A. C.; Labrador, A. W.; vonRosenvinge, T. T.; Wiedenbeck, M. E.

    2009-01-01

    We discuss observations of energetic neutral hydrogen atoms (ENAs) from a solar flare/coronal mass ejection event reported by Mewaldt et al. (2009). The observations were made during the 5 December 2006 X9 solar flare, located at E79, by the Low Energy Telescopes (LETs) on STEREO A and B. Prior to the arrival of the main solar energetic particle (SEP) event at Earth, both LETs observed a sudden burst of 1.6 to 15 MeV particles arriving from the Sun. The derived solar emission profile, arrival directions, and energy spectrum all show that the atoms produced by either flare or shock-accelerated protons. RHESSI measurements of the 2.2-MeV gamma-ray line provide an estimate of the number of interacting flare-accelerated protons in this event, which leads to an improved estimate of ENA production by flare-accelerated protons. CME-driven shock acceleration is also considered. Taking into account ENA losses, we conclude that the observed ENAs must have been produced in the high corona at heliocentric distances .2 solar radii.

  8. Selection rule engineering of forbidden transitions of a hydrogen atom near a nanogap

    Directory of Open Access Journals (Sweden)

    Kim Hyunyoung Y.

    2018-01-01

    Full Text Available We perform an analytical study on the allowance of forbidden transitions for a hydrogen atom placed near line dipole sources, mimicking light emanating from a one-dimensional metallic nanogap. It is shown that the rapid variation of the electric field vector, inevitable in the near zone, completely breaks the selection rule of Δl=±1. While the forbidden transitions between spherically symmetric S states, such as 2S to 1S or 3S to 1S (Δl=0, are rather robust against selection rule breakage, Δl=±2 transitions such as between 3D and 1S or 3D and 2S states are very vulnerable to the spatial variation of the perturbing electric field. Transitions between 2S and 3D states are enhanced by many orders of magnitude, aided by the quadratic nature of both the perturbing Hamiltonian and D wavefunctions. The forbidden dipole moment, which approaches one Bohr radius times the electric charge in the vicinity of the gap, can be written in a simple closed form owing to the one-dimensional nature of our gap. With large enough effective volume together with the symmetric nature of the excited state wavefunctions, our work paves way towards atomic physics application of infinitely long nanogaps.

  9. Experimental and numerical investigations of the dry-low-NOx hydrogen micromix combustion chamber of an industrial gas turbine

    OpenAIRE

    Haj Ayed, A.; Kusterer, K; Funke, H.H.-W.; J. Keinz; Striegan, C.; Bohn, D

    2015-01-01

    Combined with the use of renewable energy sources for its production, hydrogen represents a possible alternative gas turbine fuel within future low emission power generation. Due to the large difference in the physical properties of hydrogen compared to other fuels such as natural gas, well established gas turbine combustion systems cannot be directly applied for dry-low-NOx (DLN) hydrogen combustion. Thus, the development of DLN combustion technologies is an essential and challenging task fo...

  10. Mutual neutralization of atomic rare-gas cations (Ne(+), Ar(+), Kr(+), Xe(+)) with atomic halide anions (Cl(-), Br(-), I(-)).

    Science.gov (United States)

    Shuman, Nicholas S; Miller, Thomas M; Johnsen, Rainer; Viggiano, Albert A

    2014-01-28

    We report thermal rate coefficients for 12 reactions of rare gas cations (Ne(+), Ar(+), Kr(+), Xe(+)) with halide anions (Cl(-), Br(-), I(-)), comprising both mutual neutralization (MN) and transfer ionization. No rate coefficients have been previously reported for these reactions; however, the development of the Variable Electron and Neutral Density Attachment Mass Spectrometry technique makes it possible to measure the difference of the rate coefficients for pairs of parallel reactions in a Flowing Afterglow-Langmuir Probe apparatus. Measurements of 18 such combinations of competing reaction pairs yield an over-determined data set from which a consistent set of rate coefficients of the 12 MN reactions can be deduced. Unlike rate coefficients of MN reactions involving at least one polyatomic ion, which vary by at most a factor of ∼3, those of the atom-atom reactions vary by at least a factor 60 depending on the species. It is found that the rate coefficients involving light rare-gas ions are larger than those for the heavier rare-gas ions, but the opposite trend is observed in the progression from Cl(-) to I(-). The largest rate coefficient is 6.5 × 10(-8) cm(3) s(-1) for Ne(+) with I(-). Rate coefficients for Ar(+), Kr(+), and Xe(+) reacting with Br2 (-) are also reported.

  11. 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...... 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....

  12. Compressed hydrogen-rich fuel gas (CHFG) from wet biomass by reforming in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Penninger, Johannes M.L.; Maass, Georg J.J. [SPARQLE International B.V., Hasebroekstraat 1, 7552 VX Hengelo (Netherlands); Rep, Marco [BTG Biomass Technology Group B.V., Pantheon 12, 7521 PR Enschede (Netherlands)

    2007-07-15

    Aqueous condensate produced from biomass by flash pyrolysis is a clean feedstock for gas production by reforming at supercritical water conditions of 600-650 {sup circle} C and 28-30 MPa. Low concentrations of soda ash in the condensate reduce the CO content of the reformer gas to about 2% and proportionally increase the hydrogen content. This lean-CO gas appears as a primary candidate for upgrading to CHFG quality. Desk studies, reported in this paper, concern the design of a conceptual gas conditioning process and reveal interesting potential for production of CHFG, free of CO and CO{sub 2}, a hydrogen content of 50% with a pressure of 30 MPa, without the need for gas compression. The high processing pressure provides for small equipment size and low energy consumption. (author)

  13. ENGINEERING DEVELOPMENT OF CERAMIC MEMBRANE REACTOR SYSTEM FOR CONVERTING NATURAL GAS TO HYDROGEN AND SYNTHESIS GAS FOR LIQUID TRANSPORTATION FUELS

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-01-01

    The objective of this contract is to research, develop and demonstrate a novel ceramic membrane reactor system for the low-cost conversion of natural gas to synthesis gas and hydrogen for liquid transportation fuels: the ITM Syngas process. Through an eight-year, three-phase program, the technology will be developed and scaled up to obtain the technical, engineering, operating and economic data necessary for the final step to full commercialization of the Gas-to-Liquids (GTL) conversion technology. This report is a summary of activities through December 1999.

  14. Informing hazardous zones for on-board maritime hydrogen liquid and gas systems

    Energy Technology Data Exchange (ETDEWEB)

    Blaylock, Myra L. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Pratt, Joseph William [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Bran Anleu, Gabriela A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Proctor, Camron [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2018-01-01

    The significantly higher buoyancy of hydrogen compared to natural gas means that hazardous zones defined in the IGF code may be inaccurate if applied to hydrogen. This could place undue burden on ship design or could lead to situations that are unknowingly unsafe. We present dispersion analyses to examine three vessel case studies: (1) abnormal external vents of full blowdown of a liquid hydrogen tank due to a failed relief device in still air and with crosswind; (2) vents due to naturally-occurring boil-off of liquid within the tank; and (3) a leak from the pipes leading into the fuel cell room. The size of the hydrogen plumes resulting from a blowdown of the tank depend greatly on the wind conditions. It was also found that for normal operations releasing a small amount of "boil- off" gas to regulate the pressure in the tank does not create flammable concentrations.

  15. Use of a PhET Interactive Simulation in General Chemistry Laboratory: Models of the Hydrogen Atom

    Science.gov (United States)

    Clark, Ted M.; Chamberlain, Julia M.

    2014-01-01

    An activity supporting the PhET interactive simulation, Models of the Hydrogen Atom, has been designed and used in the laboratory portion of a general chemistry course. This article describes the framework used to successfully accomplish implementation on a large scale. The activity guides students through a comparison and analysis of the six…

  16. 20(R- and 20(S-Simarolide Epimers Isolated from Simaba cuneata: Chemical Shifts Assignment of Carbon and Hydrogen Atoms

    Directory of Open Access Journals (Sweden)

    Vieira Ivo José Curcino

    1999-01-01

    Full Text Available The C25-quassinoids 20(R- and 20(S-simarolide were isolated from Simaba cuneata, Simaroubaceae. The structures of these two compounds were characterized by spectral data, including 1D and 2D NMR spectra which were also used for the complete assignment of the carbon and hydrogen atom chemical shifts.

  17. Visualization of a Large Set of Hydrogen Atomic Orbital Contours Using New and Expanded Sets of Parametric Equations

    Science.gov (United States)

    Rhile, Ian J.

    2014-01-01

    Atomic orbitals are a theme throughout the undergraduate chemistry curriculum, and visualizing them has been a theme in this journal. Contour plots as isosurfaces or contour lines in a plane are the most familiar representations of the hydrogen wave functions. In these representations, a surface of a fixed value of the wave function ? is plotted…

  18. Single crystal to single crystal transformation and hydrogen-atom transfer upon oxidation of a cerium coordination compound.

    Science.gov (United States)

    Williams, Ursula J; Mahoney, Brian D; Lewis, Andrew J; DeGregorio, Patrick T; Carroll, Patrick J; Schelter, Eric J

    2013-04-15

    Trivalent and tetravalent cerium compounds of the octamethyltetraazaannulene (H2omtaa) ligand have been synthesized. Electrochemical analysis shows a strong thermodynamic preference for the formal cerium(IV) oxidation state. Oxidation of the cerium(III) congener Ce(Homtaa)(omtaa) occurs by hydrogen-atom transfer that includes a single crystal to single crystal transformation upon exposure to an ambient atmosphere.

  19. Complete classification of qualitatively different perturbations of the hydrogen atom in weak near-orthogonal electric and magnetic fields

    NARCIS (Netherlands)

    Efstathiou, K.; Lukina, O. V.; Sadovskii, D. A.

    2009-01-01

    We consider perturbations of the hydrogen atom by sufficiently small homogeneous static electric and magnetic fields in near-orthogonal configurations. Normalization of the Keplerian symmetry reveals that in the parameter space such systems belong in a 'zone' of systems close to the 1: 1 resonance,

  20. Stationary inverted Lyman population formed from incandescently heated hydrogen gas with certain catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Randell L; Ray, Paresh C; Mayo, Robert M [BlackLight Power, Inc., 493 Old Trenton Road, Cranbury, NJ 08512 (United States)

    2003-07-07

    A new chemically generated plasma source is reported. The presence of gaseous Rb{sup +} or K{sup +} ions with thermally dissociated hydrogen formed a low applied temperature, extremely low voltage plasma called a resonant transfer or rt-plasma having strong vacuum ultraviolet emission. We propose an energetic catalytic reaction involving a resonant energy transfer between hydrogen atoms and Rb{sup +} or 2K{sup +} since Rb{sup +} to Rb{sup 2+}, 2K{sup +} to K + K{sup 2+}, and K to K{sup 3+} each provide a reaction with a net enthalpy equal to the potential energy of atomic hydrogen. Remarkably, a stationary inverted Lyman population was observed; thus, these catalytic reactions may pump a cw HI laser as predicted by a collisional radiative model used to determine that the observed overpopulation was above threshold.

  1. Theoretical investigation of the coupling between hydrogen-atom transfer and stacking interaction in adenine-thymine dimers.

    Science.gov (United States)

    Villani, Giovanni

    2013-04-15

    Three different dimers of the adenine-thymine (A-T) base pair are studied to point out the changes of important properties (structure, atomic charge, energy and so on) induced by coupling between the movement of the atoms in the hydrogen bonds and the stacking interaction. The comparison of these results with those for the A-T monomer system explains the role of the stacking interaction in the hydrogen-atom transfer in this biologically important base pair. The results support the idea that this coupling depends on the exact dimer considered and is different for the N-N and N-O hydrogen bonds. In particular, the correlation between the hydrogen transfer and the stacking interaction is more relevant for the N-N bridge than for the N-O one. Also, the two different mechanisms of two-hydrogen transfer (step by step and concerted) can be modified by the stacking interaction between the base pairs. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Hyperbaric oxygen therapy for the prevention of arterial gas embolism in food grade hydrogen peroxide ingestion.

    Science.gov (United States)

    Hendriksen, Stephen M; Menth, Nicholas L; Westgard, Bjorn C; Cole, Jon B; Walter, Joseph W; Masters, Thomas C; Logue, Christopher J

    2017-05-01

    Food grade hydrogen peroxide ingestion is a relatively rare presentation to the emergency department. There are no defined guidelines at this time regarding the treatment of such exposures, and providers may not be familiar with the potential complications associated with high concentration hydrogen peroxide ingestions. In this case series, we describe four patients who consumed 35% hydrogen peroxide, presented to the emergency department, and were treated with hyperbaric oxygen therapy. Two of the four patients were critically ill requiring intubation. All four patients had evidence on CT or ultrasound of venous gas emboli and intubated patients were treated as if they had an arterial gas embolism since an exam could not be followed. After hyperbaric oxygen therapy each patient was discharged from the hospital neurologically intact with no other associated organ injuries related to vascular gas emboli. Hyperbaric oxygen therapy is an effective treatment for patients with vascular gas emboli after high concentration hydrogen peroxide ingestion. It is the treatment of choice for any impending, suspected, or diagnosed arterial gas embolism. Further research is needed to determine which patients with portal venous gas emboli should be treated with hyperbaric oxygen therapy. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Treating landfill gas hydrogen sulphide with mineral wool waste (MWW) and rod mill waste (RMW).

    Science.gov (United States)

    Bergersen, Ove; Haarstad, Ketil

    2014-01-01

    Hydrogen sulphide (H2S) gas is a major odorant at municipal landfills. The gas can be generated from different waste fractions, for example demolition waste containing gypsum based plaster board. The removal of H2S from landfill gas was investigated by filtering it through mineral wool waste products. The flow of gas varied from 0.3 l/min to 3.0 l/min. The gas was typical for landfill gas with a mean H2S concentration of ca. 4500 ppm. The results show that the sulphide gas can effectively be removed by mineral wool waste products. The ratios of the estimated potential for sulphide precipitation were 19:1 for rod mill waste (RMW) and mineral wool waste (MWW). A filter consisting of a mixture of MWW and RMW, with a vertical perforated gas tube through the center of filter material and with a downward gas flow, removed 98% of the sulfide gas over a period of 80 days. A downward gas flow was more efficient in contacting the filter materials. Mineral wool waste products are effective in removing hydrogen sulphide from landfill gas given an adequate contact time and water content in the filter material. Based on the estimated sulphide removal potential of mineral wool and rod mill waste of 14 g/kg and 261 g/kg, and assuming an average sulphide gas concentration of 4500 ppm, the removal capacity in the filter materials has been estimated to last between 11 and 308 days. At the studied location the experimental gas flow was 100 times less than the actual gas flow. We believe that the system described here can be upscaled in order to treat this gas flow. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2008-09-01

    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-blast-wave descriptions of laser ablation plume expansion in gas.

  5. The evolution of structural and chemical heterogeneity during rapid solidification at gas atomization

    Science.gov (United States)

    Golod, V. M.; Sufiiarov, V. Sh

    2017-04-01

    Gas atomization is a high-performance process for manufacturing superfine metal powders. Formation of the powder particles takes place primarily through the fragmentation of alloy melt flow with high-pressure inert gas, which leads to the formation of non-uniform sized micron-scale particles and subsequent their rapid solidification due to heat exchange with gas environment. The article presents results of computer modeling of crystallization process, simulation and experimental studies of the cellular-dendrite structure formation and microsegregation in different size particles. It presents results of adaptation of the approach for local nonequilibrium solidification to conditions of crystallization at gas atomization, detected border values of the particle size at which it is possible a manifestation of diffusionless crystallization.

  6. Cerebral arterial gas embolism after pre-flight ingestion of hydrogen peroxide.

    Science.gov (United States)

    Smedley, Ben L; Gault, Alan; Gawthrope, Ian C

    2016-06-01

    Cerebral arterial gas embolism (CAGE) is a feared complication of ambient depressurisation and can also be a complication of hydrogen peroxide ingestion. We present an unusual case of CAGE in a 57-year-old woman exposed to both of these risk factors. We describe her subsequent successful treatment with hyperbaric oxygen, despite a 72-hour delay in initial presentation and diagnosis, and discuss the safety of aero-medical transfer following hydrogen peroxide ingestions.

  7. Repulsive tip tilting as the dominant mechanism for hydrogen bond-like features in atomic force microscopy imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Alex J. [Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Sakai, Yuki [Center for Computational Materials, Institution for Computational Engineering and Sciences, The University of Texas at Austin, Austin, Texas, 78712 (United States); Kim, Minjung [Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Chelikowsky, James R. [Center for Computational Materials, Institute for Computational Engineering and Sciences, Departments of Physics and Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States)

    2016-05-09

    Experimental atomic force microscopy (AFM) studies have reported distinct features in regions with little electron density for various organic systems. These unexpected features have been proposed to be a direct visualization of intermolecular hydrogen bonding. Here, we apply a computational method using ab initio real-space pseudopotentials along with a scheme to account for tip tilting to simulate AFM images of the 8-hydroxyquinoline dimer and related systems to develop an understanding of the imaging mechanism for hydrogen bonds. We find that contrast for the observed “hydrogen bond” feature comes not from the electrostatic character of the bonds themselves but rather from repulsive tip tilting induced by neighboring electron-rich atoms.

  8. Detection of hydrogen gas-producing anaerobes in refuse-derived fuel (RDF) pellets.

    Science.gov (United States)

    Sakka, Makiko; Kimura, Tetsuya; Ohmiya, Kunio; Sakka, Kazuo

    2005-11-01

    Recently, we reported that refuse-derived fuel (RDF) pellets contain a relatively high number of viable bacterial cells and that these bacteria generate heat and hydrogen gas during fermentation under wet conditions. In this study we analyzed bacterial cell numbers of RDF samples manufactured with different concentrations of calcium hydroxide, which is usually added to waste materials for the prevention of rotting of food wastes and the acceleration of drying of solid wastes, and determined the amount of hydrogen gas produced by them under wet conditions. Furthermore, we analyzed microflora of the RDF samples before and during fermentation by denaturing gradient gel electrophoresis of 16S rDNA followed by sequencing. We found that the RDF samples contained various kinds of clostridia capable of producing hydrogen gas.

  9. Microbial Electrolysis Cells for High Yield Hydrogen Gas Production from Organic Matter

    KAUST Repository

    Logan, Bruce E.

    2008-12-01

    The use of electrochemically active bacteria to break down organic matter, combined with the addition of a small voltage (>0.2 V in practice) in specially designed microbial electrolysis cells (MECs), can result in a high yield of hydrogen gas. While microbial electrolysis was invented only a few years ago, rapid developments have led to hydrogen yields approaching 100%, energy yields based on electrical energy input many times greater than that possible by water electrolysis, and increased gas production rates. MECs used to make hydrogen gas are similar in design to microbial fuel cells (MFCs) that produce electricity, but there are important differences in architecture and analytical methods used to evaluate performance. We review here the materials, architectures, performance, and energy efficiencies of these MEC systems that show promise as a method for renewable and sustainable energy production, and wastewater treatment. © 2008 American Chemical Society.

  10. Microbial electrolysis cells for high yield hydrogen gas production from organic matter.

    Science.gov (United States)

    Logan, Bruce E; Call, Douglas; Cheng, Shaoan; Hamelers, Hubertus V M; Sleutels, Tom H J A; Jeremiasse, Adriaan W; Rozendal, René A

    2008-12-01

    The use of electrochemically active bacteria to break down organic matter, combined with the addition of a small voltage (> 0.2 V in practice) in specially designed microbial electrolysis cells (MECs), can result in a high yield of hydrogen gas. While microbial electrolysis was invented only a few years ago, rapid developments have led to hydrogen yields approaching 100%, energy yields based on electrical energy input many times greater than that possible by water electrolysis, and increased gas production rates. MECs used to make hydrogen gas are similar in design to microbial fuel cells (MFCs) that produce electricity, but there are important differences in architecture and analytical methods used to evaluate performance. We review here the materials, architectures, performance, and energy efficiencies of these MEC systems that show promise as a method for renewable and sustainable energy production, and wastewater treatment.

  11. MOLECULAR AND ATOMIC LINE SURVEYS OF GALAXIES. I. THE DENSE, STAR-FORMING GAS PHASE AS A BEACON

    Energy Technology Data Exchange (ETDEWEB)

    Geach, James E. [Department of Physics, McGill University, 3600 rue University, Montreal, Quebec H3A 2T8 (Canada); Papadopoulos, Padelis P., E-mail: jimgeach@physics.mcgill.ca, E-mail: padelis@mpifr-bonn.mpg.de [Max Planck Institute for Radioastronomy, Auf dem Huegel 69, D-53121 Bonn (Germany)

    2012-10-01

    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 [C II] atomic emission lines in blind redshift surveys in the submillimeter-centimeter spectral regime. Our model uses (1) recently available HCN spectral line energy distributions (SLEDs) of local luminous infrared galaxies (LIRGs, L{sub IR} > 10{sup 11} L{sub Sun }), (2) a value for {epsilon}{sub *} = SFR/M{sub dense}(H{sub 2}) provided by new developments in the study of star formation feedback on the interstellar medium, and (3) 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 [C II] as the most important of the far-infrared cooling lines. Optimal blind surveys with the Atacama Large Millimeter Array (ALMA) could potentially detect very distant (z {approx} 10-12) [C II] emitters in the {>=}ULIRG galaxy class at a rate of {approx}0.1-1 hr{sup -1} (although this prediction is strongly dependent on the star formation and enrichment history at this early epoch), whereas the (high-frequency) Square Kilometer Array will be capable of blindly detecting z > 3 low-J CO emitters at a rate of {approx}40-70 hr{sup -1}. The [C II] line holds special promise for detecting metal-poor systems with extensive reservoirs of CO-dark molecular gas where detection rates with ALMA can reach up to 2-7 hr{sup -1} in Bands 4-6.

  12. Hydrogen enriched compressed natural gas (HCNG: A futuristic fuel for internal combustion engines

    Directory of Open Access Journals (Sweden)

    Nanthagopal Kasianantham

    2011-01-01

    Full Text Available Air pollution is fast becoming a serious global problem with increasing population and its subsequent demands. This has resulted in increased usage of hydrogen as fuel for internal combustion engines. Hydrogen resources are vast and it is considered as one of the most promising fuel for automotive sector. As the required hydrogen infrastructure and refueling stations are not meeting the demand, widespread introduction of hydrogen vehicles is not possible in the near future. One of the solutions for this hurdle is to blend hydrogen with methane. Such types of blends take benefit of the unique combustion properties of hydrogen and at the same time reduce the demand for pure hydrogen. Enriching natural gas with hydrogen could be a potential alternative to common hydrocarbon fuels for internal combustion engine applications. Many researchers are working on this for the last few years and work is now focused on how to use this kind of fuel to its maximum extent. This technical note is an assessment of HCNG usage in case of internal combustion engines. Several examples and their salient features have been discussed. Finally, overall effects of hydrogen addition on an engine fueled with HCNG under various conditions are illustrated. In addition, the scope and challenges being faced in this area of research are clearly described.

  13. Kinetics, mechanism, and thermochemistry of the gas-phase reaction of atomic chlorine with pyridine.

    Science.gov (United States)

    Zhao, Z; Huskey, D T; Olsen, K J; Nicovich, J M; McKee, M L; Wine, P H

    2007-08-21

    A laser flash photolysis-resonance fluorescence technique has been employed to study the kinetics of the reaction of atomic chlorine with pyridine (C(5)H(5)N) as a function of temperature (215-435 K) and pressure (25-250 Torr) in nitrogen bath gas. At T> or = 299 K, measured rate coefficients are pressure independent and a significant H/D kinetic isotope effect is observed, suggesting that hydrogen abstraction is the dominant reaction pathway. The following Arrhenius expression adequately describes all kinetic data at 299-435 K for C(5)H(5)N: k(1a) = (2.08 +/- 0.47) x 10(-11) exp[-(1410 +/- 80)/T] cm(3) molecule(-1) s(-1) (uncertainties are 2sigma, precision only). At 216 K rate coefficients are pressure dependent and are much faster than computed from the above Arrhenius expression for the H-abstraction pathway, suggesting that the dominant reaction pathway at low temperature is formation of a stable adduct. Over the ranges of temperature, pressure, and pyridine concentration investigated, the adduct undergoes dissociation on the time scale of our experiments (10(-5)-10(-2) s) and establishes an equilibrium with Cl and pyridine. Equilibrium constants for adduct formation and dissociation are determined from the forward and reverse rate coefficients. Second- and third-law analyses of the equilibrium data lead to the following thermochemical parameters for the addition reaction: Delta(r)H = -47.2 +/- 2.8 kJ mol(-1), Delta(r)H = -46.7 +/- 3.2 kJ mol(-1), and Delta(r)S = -98.7 +/- 6.5 J mol(-1) K(-1). The enthalpy changes derived from our data are in good agreement with ab initio calculations reported in the literature (which suggest that the adduct structure is planar and involves formation of an N-Cl sigma-bond). In conjunction with the well-known heats of formation of atomic chlorine and pyridine, the above Delta(r)H values lead to the following heats of formation for C(5)H(5)N-Cl at 298 K and 0 K: Delta(f)H = 216.0 +/- 4.1 kJ mol(-1), Delta(f)H = 233.4 +/- 4.6 k

  14. Measurement and interpretation of threshold stress intensity factors for steels in high-pressure hydrogen gas.

    Energy Technology Data Exchange (ETDEWEB)

    Dadfarnia, Mohsen (University of Illinois at Urbana-Champaign, Urbana, IL); Nibur, Kevin A.; San Marchi, Christopher W.; Sofronis, Petros (University of Illinois at Urbana-Champaign, Urbana, IL); Somerday, Brian P.; Foulk, James W., III; Hayden, Gary A. (CP Industries, McKeesport, PA)

    2010-07-01

    Threshold stress intensity factors were measured in high-pressure hydrogen gas for a variety of low alloy ferritic steels using both constant crack opening displacement and rising crack opening displacement procedures. The sustained load cracking procedures are generally consistent with those in ASME Article KD-10 of Section VIII Division 3 of the Boiler and Pressure Vessel Code, which was recently published to guide design of high-pressure hydrogen vessels. Three definitions of threshold were established for the two test methods: K{sub THi}* is the maximum applied stress intensity factor for which no crack extension was observed under constant displacement; K{sub THa} is the stress intensity factor at the arrest position for a crack that extended under constant displacement; and K{sub JH} is the stress intensity factor at the onset of crack extension under rising displacement. The apparent crack initiation threshold under constant displacement, K{sub THi}*, and the crack arrest threshold, K{sub THa}, were both found to be non-conservative due to the hydrogen exposure and crack-tip deformation histories associated with typical procedures for sustained-load cracking tests under constant displacement. In contrast, K{sub JH}, which is measured under concurrent rising displacement and hydrogen gas exposure, provides a more conservative hydrogen-assisted fracture threshold that is relevant to structural components in which sub-critical crack extension is driven by internal hydrogen gas pressure.

  15. Advances of zeolite based membrane for hydrogen production via water gas shift reaction

    Science.gov (United States)

    Makertihartha, I. G. B. N.; Zunita, M.; Rizki, Z.; Dharmawijaya, P. T.

    2017-07-01

    Hydrogen is considered as a promising energy vector which can be obtained from various renewable sources. However, an efficient hydrogen production technology is still challenging. One technology to produce hydrogen with very high capacity with low cost is through water gas shift (WGS) reaction. Water gas shift reaction is an equilibrium reaction that produces hydrogen from syngas mixture by the introduction of steam. Conventional WGS reaction employs two or more reactors in series with inter-cooling to maximize conversion for a given volume of catalyst. Membrane reactor as new technology can cope several drawbacks of conventional reactor by removing reaction product and the reaction will favour towards product formation. Zeolite has properties namely high temperature, chemical resistant, and low price makes it suitable for membrane reactor applications. Moreover, it has been employed for years as hydrogen selective layer. This review paper is focusing on the development of membrane reactor for efficient water gas shift reaction to produce high purity hydrogen and carbon dioxide. Development of membrane reactor is discussed further related to its modification towards efficient reaction and separation from WGS reaction mixture. Moreover, zeolite framework suitable for WGS membrane reactor will be discussed more deeply.

  16. Commissioning of the cryogenic hydrogen system in J-PARC: Preliminary operation by helium gas

    CERN Document Server

    Aso, T; Hasegawa, S; Ohtsu, K; Uehara, T; Kawakami, Y; Sakurayama, H; Maekawa, F; Futakawa, M; Ushijima, I

    2009-01-01

    A cryogenic hydrogen circulation system to cool the moderators for the spallation neutron source in J-PARC has been constructed. This system provides supercritical hydrogen at the temperature of 20 K and the pressure of 1.5 MPa to three moderators and absorbs nuclear heating produced in the moderators. The cryogenic hydrogen system commissioning was started. In January 2008, for the first time, we carried out a cryogenic test of the whole system, in which helium gas was used in stead of hydrogen. The cryogenic hydrogen system can be cooled down to 18 K within 30 hours, and be kept to be the rated condition for 36 hours without any problems. We confirmed the soundness of each component such as circulation pump and operation control system.

  17. Development of the Raman lidar system for remote hydrogen gas detection

    Energy Technology Data Exchange (ETDEWEB)

    Choi, In Young; Baik, Sung Hoon; Park, Seung Kyu; Park, Nak Gyu; Choi, Young Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Detection of hydrogen (H{sub 2}) gas leakage is very important for safety of the nuclear power plant because H{sub 2} gas is very flammable and explosive. H{sub 2} gas is generated by oxidizing the nuclear fuel cladding during the critical accident and generated H{sub 2} gas leads to serious secondary damages in the containment building of nuclear power plant. Thus, various H{sub 2} gas detection techniques are used in the nuclear power plant such as catalytic combustion sensors, semiconducting oxide sensors, thermal conductivity sensors and electrochemical sensor. A Raman lidar (Light Detection And Ranging) system for remote detection of the H{sub 2} gas can cover the area in the containment building of a nuclear power plant. H{sub 2} gas has a very strong Raman Effect, and H{sub 2} Raman cells have been widely used for laser wavelength conversion. In this study, Raman lidar system was developed for H{sub 2} gas detection used in the containment building of nuclear power plant. In this study, remote hydrogen gas detection devices and measuring algorithm are developed by using the Raman lidar method. Through the experiment, we proved that our developed Raman lidar system was possible to measure the N{sub 2} and H{sub 2} gas scattering signal remotely.

  18. Low-Dimensional Palladium Nanostructures for Fast and Reliable Hydrogen Gas Detection

    Directory of Open Access Journals (Sweden)

    Wooyoung Lee

    2011-01-01

    Full Text Available Palladium (Pd has received attention as an ideal hydrogen sensor material due to its properties such as high sensitivity and selectivity to hydrogen gas, fast response, and operability at room temperature. Interestingly, various Pd nanostructures that have been realized by recent developments in nanotechnologies are known to show better performance than bulk Pd. This review highlights the characteristic properties, issues, and their possible solutions of hydrogen sensors based on the low-dimensional Pd nanostructures with more emphasis on Pd thin films and Pd nanowires. The finite size effects, relative strengths and weaknesses of the respective Pd nanostructures are discussed in terms of performance, manufacturability, and practical applicability.

  19. Development of a new method for hydrogen isotope analysis of trace hydrocarbons in natural gas samples

    Directory of Open Access Journals (Sweden)

    Xibin Wang

    2016-12-01

    Full Text Available A new method had been developed for the analysis of hydrogen isotopic composition of trace hydrocarbons in natural gas samples by using solid phase microextraction (SPME combined with gas chromatography-isotope ratio mass spectrometry (GC/IRMS. In this study, the SPME technique had been initially introduced to achieve the enrichment of trace content of hydrocarbons with low abundance and coupled to GC/IRMS for hydrogen isotopic analysis. The main parameters, including the equilibration time, extraction temperature, and the fiber type, were systematically optimized. The results not only demonstrated that high extraction yield was true but also shows that the hydrogen isotopic fractionation was not observed during the extraction process, when the SPME device fitted with polydimethylsiloxane/divinylbenzene/carbon molecular sieve (PDMS/DVB/CAR fiber. The applications of SPME-GC/IRMS method were evaluated by using natural gas samples collected from different sedimentary basins; the standard deviation (SD was better than 4‰ for reproducible measurements; and also, the hydrogen isotope values from C1 to C9 can be obtained with satisfying repeatability. The SPME-GC/IRMS method fitted with PDMS/DVB/CAR fiber is well suited for the preconcentration of trace hydrocarbons, and provides a reliable hydrogen isotopic analysis for trace hydrocarbons in natural gas samples.

  20. In situ Gas Conditioning in Fuel Reforming for Hydrogen Generation

    Energy Technology Data Exchange (ETDEWEB)

    Bandi, A.; Specht, M.; Sichler, P.; Nicoloso, N.

    2002-09-20

    The production of hydrogen for fuel cell applications requires cost and energy efficient technologies. The Absorption Enhanced Reforming (AER), developed at ZSW with industrial partners, is aimed to simplify the process by using a high temperature in situ CO2 absorption. The in situ CO2 removal results in shifting the steam reforming reaction equilibrium towards increased hydrogen concentration (up to 95 vol%). The key part of the process is the high temperature CO2 absorbent. In this contribution results of Thermal Gravimetric Analysis (TGA) investigations on natural minerals, dolomites, silicates and synthetic absorbent materials in regard of their CO2 absorption capacity and absorption/desorption cyclic stability are presented and discussed. It has been found that the inert parts of the absorbent materials have a structure stabilizing effect, leading to an improved cyclic stability of the materials.

  1. Numerical estimation of ultrasonic production of hydrogen: Effect of ideal and real gas based models.

    Science.gov (United States)

    Kerboua, Kaouther; Hamdaoui, Oualid

    2018-01-01

    Based on two different assumptions regarding the equation describing the state of the gases within an acoustic cavitation bubble, this paper studies the sonochemical production of hydrogen, through two numerical models treating the evolution of a chemical mechanism within a single bubble saturated with oxygen during an oscillation cycle in water. The first approach is built on an ideal gas model, while the second one is founded on Van der Waals equation, and the main objective was to analyze the effect of the considered state equation on the ultrasonic hydrogen production retrieved by simulation under various operating conditions. The obtained results show that even when the second approach gives higher values of temperature, pressure and total free radicals production, yield of hydrogen does not follow the same trend. When comparing the results released by both models regarding hydrogen production, it was noticed that the ratio of the molar amount of hydrogen is frequency and acoustic amplitude dependent. The use of Van der Waals equation leads to higher quantities of hydrogen under low acoustic amplitude and high frequencies, while employing ideal gas law based model gains the upper hand regarding hydrogen production at low frequencies and high acoustic amplitudes. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Experimental and numerical investigations of the dry-low-NOx hydrogen micromix combustion chamber of an industrial gas turbine

    National Research Council Canada - National Science Library

    Haj Ayed, A; Kusterer, K; Funke, H.H.-W; Keinz, J; Striegan, C; Bohn, D

    2015-01-01

    .... Due to the large difference in the physical properties of hydrogen compared to other fuels such as natural gas, well established gas turbine combustion systems cannot be directly applied for dry-low-NOx (DLN...

  3. Electrochemical gas chromatographic detection of hydrogen sulfide at PPM and PPB levels.

    Science.gov (United States)

    Stetter, J R; Sedlak, J M; Blurton, K F

    1977-01-01

    An electrochemical detector for gas chromatographic analysis of hydrogen sulfide is described and its operating characteristics are discussed. The detector operation is based upon the measurement of the current when hydrogen sulfide is electrochemically oxidized at a diffusion electrode. The lower detectable limit was 3 X 10(-12) grams H2S, the precision was 0.5% and analysis was achieved within 2 minutes. Accuracy was limited principally by the preparation of calibration samples and the availability of standard reference gas mixtures.

  4. Gas Atomization Equipment Statement of Work and Specification for Engineering design, Fabrication, Testing, and Installation

    Energy Technology Data Exchange (ETDEWEB)

    Boutaleb, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pluschkell, T. P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-11-30

    The Gas Atomization Equipment will be used to fabricate metallic powder suitable for Powder Bed Fusion additive Manufacturing material to support Lawrence Livermore National Laboratory (LLNL) research and development. The project will modernize our capabilities to develop spherical reactive, refractory, and radioactive powders in the 10-75 μm diameter size range at LLNL.

  5. 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)

  6. Hydrogen

    Directory of Open Access Journals (Sweden)

    John O’M. Bockris

    2011-11-01

    Full Text Available The idea of a “Hydrogen Economy” is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO2 in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H2 from the electrolyzer. Methanol made with CO2 from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan. Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  7. Intermolecular and intramolecular hydrogen bonds involving fluorine atoms: implications for recognition, selectivity, and chemical properties.

    Science.gov (United States)

    Dalvit, Claudio; Vulpetti, Anna

    2012-02-06

    A correlation between 19F NMR isotropic chemical shift and close intermolecular F⋅⋅⋅H-X contacts (with X=N or O) has been identified upon analysis of the X-ray crystal structures of fluorinated molecules listed in the Cambridge Structural Database (CSD). An optimal F⋅⋅⋅X distance involving primary and shielded secondary fluorine atoms in hydrogen-bond formation along with a correlation between F⋅⋅⋅H distance and F⋅⋅⋅H-X angle were also derived from the analysis. The hydrogen bonds involving fluorine are relevant, not only for the recognition mechanism and stabilization of a preferred conformation, but also for improvement in the permeability of the molecules, as shown with examples taken from a proprietary database. Results of an analysis of the small number of fluorine-containing natural products listed in the Protein Data Bank (PDB) appear to strengthen the derived correlation between 19F NMR isotropic chemical shift and interactions involving fluorine (also known as the "rule of shielding") and provides a hypothesis for the recognition mechanism and catalytic activity of specific enzymes. Novel chemical scaffolds, based on the rule of shielding, have been designed for recognizing distinct structural motifs present in proteins. It is envisaged that this approach could find useful applications in drug design for the efficient optimization of chemical fragments or promising compounds by increasing potency and selectivity against the desired biomolecular target. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Fundamental studies on kinetic isotope effect (KIE) of hydrogen isotope fractionation in natural gas systems

    Science.gov (United States)

    Ni, Y.; Ma, Q.; Ellis, G.S.; Dai, J.; Katz, B.; Zhang, S.; Tang, Y.

    2011-01-01

    Based on quantum chemistry calculations for normal octane homolytic cracking, a kinetic hydrogen isotope fractionation model for methane, ethane, and propane formation is proposed. The activation energy differences between D-substitute and non-substituted methane, ethane, and propane are 318.6, 281.7, and 280.2cal/mol, respectively. In order to determine the effect of the entropy contribution for hydrogen isotopic substitution, a transition state for ethane bond rupture was determined based on density function theory (DFT) calculations. The kinetic isotope effect (KIE) associated with bond rupture in D and H substituted ethane results in a frequency factor ratio of 1.07. Based on the proposed mathematical model of hydrogen isotope fractionation, one can potentially quantify natural gas thermal maturity from measured hydrogen isotope values. Calculated gas maturity values determined by the proposed mathematical model using ??D values in ethane from several basins in the world are in close agreement with similar predictions based on the ??13C composition of ethane. However, gas maturity values calculated from field data of methane and propane using both hydrogen and carbon kinetic isotopic models do not agree as closely. It is possible that ??D values in methane may be affected by microbial mixing and that propane values might be more susceptible to hydrogen exchange with water or to analytical errors. Although the model used in this study is quite preliminary, the results demonstrate that kinetic isotope fractionation effects in hydrogen may be useful in quantitative models of natural gas generation, and that ??D values in ethane might be more suitable for modeling than comparable values in methane and propane. ?? 2011 Elsevier Ltd.

  9. Method for converting hydrocarbon fuel into hydrogen gas and carbon dioxide

    Science.gov (United States)

    Clawson, Lawrence G.; Mitchell, William L.; Bentley, Jeffrey M.; Thijssen, Johannes H. J.

    2000-01-01

    A method for converting hydrocarbon fuel into hydrogen gas and carbon dioxide within a reformer 10 is disclosed. According to the method, a stream including an oxygen-containing gas is directed adjacent to a first vessel 18 and the oxygen-containing gas is heated. A stream including unburned fuel is introduced into the oxygen-containing gas stream to form a mixture including oxygen-containing gas and fuel. The mixture of oxygen-containing gas and unburned fuel is directed tangentially into a partial oxidation reaction zone 24 within the first vessel 18. The mixture of oxygen-containing gas and fuel is further directed through the partial oxidation reaction zone 24 to produce a heated reformate stream including hydrogen gas and carbon monoxide. Steam may also be mixed with the oxygen-containing gas and fuel, and the reformate stream from the partial oxidation reaction zone 24 directed into a steam reforming zone 26. High- and low-temperature shift reaction zones 64,76 may be employed for further fuel processing.

  10. Hydrogen atom transfer reactions of imido manganese(V) corrole: one reaction with two mechanistic pathways.

    Science.gov (United States)

    Zdilla, Michael J; Dexheimer, Jennifer L; Abu-Omar, Mahdi M

    2007-09-19

    Hydrogen atom transfer (HAT) reactions of (tpfc)MnNTs have been investigated (tpfc = 5,10,15-tris(pentafluorophenyl)corrole and Ts = p-toluenesulfonate). 9,10-Dihydroanthracene and 1,4-dihydrobenzene reduce (tpfc)MnNTs via HAT with second-order rate constants 0.16 +/- 0.03 and 0.17 +/- 0.01 M(-1) s(-1), respectively, at 22 degrees C. The products are the respective arenes, TsNH(2) and (tpfc)Mn(III). Conversion of (tpfc)MnNTs to (tpfc)Mn by reaction with dihydroanthracene exhibits isosbestic behavior, and formation of 9,9',10,10'-tetrahydrobianthracene is not observed, suggesting that the intermediate anthracene radical rebounds in a second fast step without accumulation of a Mn(IV) intermediate. The imido complex (tpfc)Mn(V)NTs abstracts a hydrogen atom from phenols as well. For example, 2,6-di-tert-butyl phenol is oxidized to the corresponding phenoxyl radical with a second-order rate constant of 0.32 +/- 0.02 M(-1) s(-1) at 22 degrees C. The other products from imido manganese(V) are TsNH(2) and the trivalent manganese corrole. Unlike reaction with dihydroarenes, when phenols are used isosbestic behavior is not observed, and formation of (tpfc)Mn(IV)(NHTs) is confirmed by EPR spectroscopy. A Hammett plot for various p-substituted 2,6-di-tert-butyl phenols yields a V-shaped dependence on sigma, with electron-donating substituents exhibiting the expected negative rho while electron-withdrawing substituents fall above the linear fit (i.e., positive rho). Similarly, a bond dissociation enthalpy (BDE) correlation places electron-withdrawing substituents above the well-defined negative slope found for the electron-donating substituents. Thus two mechanisms are established for HAT reactions in this system, namely, concerted proton-electron transfer and proton-gated electron transfer in which proton transfer is followed by electron transfer.

  11. Analysis of Energy Storage System with Distributed Hydrogen Production and Gas Turbine

    Science.gov (United States)

    Kotowicz, Janusz; Bartela, Łukasz; Dubiel-Jurgaś, Klaudia

    2017-12-01

    Paper presents the concept of energy storage system based on power-to-gas-to-power (P2G2P) technology. The system consists of a gas turbine co-firing hydrogen, which is supplied from a distributed electrolysis installations, powered by the wind farms located a short distance from the potential construction site of the gas turbine. In the paper the location of this type of investment was selected. As part of the analyses, the area of wind farms covered by the storage system and the share of the electricity production which is subjected storage has been changed. The dependence of the changed quantities on the potential of the hydrogen production and the operating time of the gas turbine was analyzed. Additionally, preliminary economic analyses of the proposed energy storage system were carried out.

  12. Analysis of Energy Storage System with Distributed Hydrogen Production and Gas Turbine

    Directory of Open Access Journals (Sweden)

    Kotowicz Janusz

    2017-12-01

    Full Text Available Paper presents the concept of energy storage system based on power-to-gas-to-power (P2G2P technology. The system consists of a gas turbine co-firing hydrogen, which is supplied from a distributed electrolysis installations, powered by the wind farms located a short distance from the potential construction site of the gas turbine. In the paper the location of this type of investment was selected. As part of the analyses, the area of wind farms covered by the storage system and the share of the electricity production which is subjected storage has been changed. The dependence of the changed quantities on the potential of the hydrogen production and the operating time of the gas turbine was analyzed. Additionally, preliminary economic analyses of the proposed energy storage system were carried out.

  13. Chlorine and hydrogen chloride gas emissions cleaning in vinylchloride production

    OpenAIRE

    Гармаш, Роман Вікторович

    2013-01-01

    The paper gives the data on mathematical modeling of simultaneous absorption of chlorine and hydrogen chloride by alkaline solutions. The mathematical model of the process includes the system of differential equations of component-wise material balance and the system of kinetic equations. The system of material balance equations describes the change in concentrations of components along the column height. For its solving it is necessary to know the numerical values of chemisorption accelerati...

  14. Biological Water-Gas Shift Conversion of Carbon Monoxide to Hydrogen: Milestone Completion Report

    Energy Technology Data Exchange (ETDEWEB)

    Amos, W. A.

    2004-01-01

    This report summarizes the results of research and economic analysis on a biological water-gas shift process for the production of hydrogen. The organism Rubrivivax gelatinosus CBS is a photosynthetic bacteria which can perform the water-gas shift reaction under anaerobic conditions. The report describes some of the technical issues regarding the process, addresses some claimed benefits of the process and presents some results from economic studies of different process configurations.

  15. The use of the natural-gas pipeline infrastructure for hydrogen transport in a changing market structure

    Energy Technology Data Exchange (ETDEWEB)

    Haeseldonckx, Dries; D' haeseleer, William [Division of Energy Conversion, University of Leuven (K.U. Leuven), Celestijnenlaan 300A, 3001 Leuven (Belgium)

    2007-07-15

    In this paper, the transport and distribution aspects of hydrogen during the transition period towards a possible full-blown hydrogen economy are carefully looked at. Firstly, the energetic and material aspects of hydrogen transport through the existing natural-gas (NG) pipeline infrastructure is discussed. Hereby, only the use of centrifugal compressors and the short-term security of supply seem to constitute a problem for the NG to hydrogen transition. Subsequently, the possibility of percentwise mixing of hydrogen into the NG bulk is dealt with. Mixtures containing up to 17 vol% of hydrogen should not cause difficulties. As soon as more hydrogen is injected, replacement of end-use applications and some pipelines will be necessary. Finally, the transition towards full-blown hydrogen transport in (previously carrying) NG pipelines is treated. Some policy guidelines are offered, both in a regulated and a liberalised energy (gas) market. As a conclusion, it can be stated that the use of hydrogen-natural gas mixtures seems well suited for the transition from natural gas to hydrogen on a distribution (low pressure) level. However, getting the hydrogen gas to the distribution grid, by means of the transport grid, remains a major issue. In the end, the structure of the market, regulated or liberalised, turns out not to be important. (author)

  16. How reliable is the Lippincott-Schroeder potential for the OH…N hydrogen bonded fragment in the gas phase?

    Science.gov (United States)

    Vener, M. V.

    1995-09-01

    Ab initio calculations at the MP2 level of theory, with a 6-31 G basis set which includes polarization functions on the atoms involved in the H bond, are performed on the hydrogen-bonded phenol-NH 3 complex. The equilibrium O…N distance ( Re) is equal to 2.837 Å. The potential profile along the proton coordinate at a fixed O…N distance V( r, Re) only one minimum. Its shape is verified by calculation of the OH stretch frequency. The Lippincott-Schroeder potential is able to reproduce the shape of the V( r, Re) function for systems with an OH…N fragment in the gas phase only if some its parameters are calibrated to fit high-level ab initio data.

  17. reaction process simulation of hydrogen gas discharge in a cold ...

    Indian Academy of Sciences (India)

    In the cold cathode electric vacuum device, under low pressure and weak ionization, elastic collision reaction is encountered by most electrons, that is, e + H2 → H2 + e and e + H → H + e, but the inelastic collision is the key method for ionizing the working gas and constituting plasma [10]. The inelastic collision has four ...

  18. Long-range dispersion interactions between Li and rare-gas atoms

    Science.gov (United States)

    Zhang, Deng-Hong; Xu, Ya-Bin; Jiang, Jun; Jiang, Li; Xie, Lu-You; Dong, Chen-Zhong

    2017-06-01

    The energy levels, oscillator strength and dipole scalar polarizabilities of Li atoms are calculated by using the relativistic semiempirical-core-potential method (RCICP). The dispersion coefficients C6 between ground 2s1/2 2p1/2,2p3/2 states of Li atom and the ground state of rare gas atoms (Ne, Ar, Kr, Xe) are calculated in JJ coupled states, in which the spin-orbital interactions are included. Present results are in good agreement with other available results. Contribution to the Topical Issue "Atomic and Molecular Data and their Applications", edited by Gordon W.F. Drake, Jung-Sik Yoon, Daiji Kato, Grzegorz Karwasz.

  19. Hydrogen Separation by Natural Zeolite Composite Membranes: Single and Multicomponent Gas Transport.

    Science.gov (United States)

    Farjoo, Afrooz; Kuznicki, Steve M; Sadrzadeh, Mohtada

    2017-10-06

    Single and multicomponent gas permeation tests were used to evaluate the performance of metal-supported clinoptilolite membranes. The efficiency of hydrogen separation from lower hydrocarbons (methane, ethane, and ethylene) was studied within the temperature and pressure ranges of 25-600 °C and 110-160 kPa, respectively. The hydrogen separation factor was found to reduce noticeably in the gas mixture compared with single gas experiments at 25 °C. The difference between the single and multicomponent gas results decreased as the temperature increased to higher than 300 °C, which is when the competitive adsorption-diffusion mechanism was replaced by Knudsen diffusion or activated diffusion mechanisms. To evaluate the effect of gas adsorption, the zeolite surface isotherms of each gas in the mixture were obtained from 25 °C to 600 °C. The results indicated negligible adsorption of individual gases at temperatures higher than 300 °C. Increasing the feed pressure resulted in a higher separation efficiency for the individual gases compared with the multicomponent mixture, due to the governing effect of the adsorptive mechanism. This study provides valuable insight into the application of natural zeolites for the separation of hydrogen from a mixture of hydrocarbons.

  20. Hydrogen Separation by Natural Zeolite Composite Membranes: Single and Multicomponent Gas Transport

    Directory of Open Access Journals (Sweden)

    Afrooz Farjoo

    2017-10-01

    Full Text Available Single and multicomponent gas permeation tests were used to evaluate the performance of metal-supported clinoptilolite membranes. The efficiency of hydrogen separation from lower hydrocarbons (methane, ethane, and ethylene was studied within the temperature and pressure ranges of 25–600 °C and 110–160 kPa, respectively. The hydrogen separation factor was found to reduce noticeably in the gas mixture compared with single gas experiments at 25 °C. The difference between the single and multicomponent gas results decreased as the temperature increased to higher than 300 °C, which is when the competitive adsorption–diffusion mechanism was replaced by Knudsen diffusion or activated diffusion mechanisms. To evaluate the effect of gas adsorption, the zeolite surface isotherms of each gas in the mixture were obtained from 25 °C to 600 °C. The results indicated negligible adsorption of individual gases at temperatures higher than 300 °C. Increasing the feed pressure resulted in a higher separation efficiency for the individual gases compared with the multicomponent mixture, due to the governing effect of the adsorptive mechanism. This study provides valuable insight into the application of natural zeolites for the separation of hydrogen from a mixture of hydrocarbons.

  1. Quantum chaos in ultracold collisions of gas-phase erbium atoms.

    Science.gov (United States)

    Frisch, Albert; Mark, Michael; Aikawa, Kiyotaka; Ferlaino, Francesca; Bohn, John L; Makrides, Constantinos; Petrov, Alexander; Kotochigova, Svetlana

    2014-03-27

    Atomic and molecular samples reduced to temperatures below one microkelvin, yet still in the gas phase, afford unprecedented energy resolution in probing and manipulating the interactions between their constituent particles. As a result of this resolution, atoms can be made to scatter resonantly on demand, through the precise control of a magnetic field. For simple atoms, such as alkalis, scattering resonances are extremely well characterized. However, ultracold physics is now poised to enter a new regime, where much more complex species can be cooled and studied, including magnetic lanthanide atoms and even molecules. For molecules, it has been speculated that a dense set of resonances in ultracold collision cross-sections will probably exhibit essentially random fluctuations, much as the observed energy spectra of nuclear scattering do. According to the Bohigas-Giannoni-Schmit conjecture, such fluctuations would imply chaotic dynamics of the underlying classical motion driving the collision. This would necessitate new ways of looking at the fundamental interactions in ultracold atomic and molecular systems, as well as perhaps new chaos-driven states of ultracold matter. Here we describe the experimental demonstration that random spectra are indeed found at ultralow temperatures. In the experiment, an ultracold gas of erbium atoms is shown to exhibit many Fano-Feshbach resonances, of the order of three per gauss for bosons. Analysis of their statistics verifies that their distribution of nearest-neighbour spacings is what one would expect from random matrix theory. The density and statistics of these resonances are explained by fully quantum mechanical scattering calculations that locate their origin in the anisotropy of the atoms' potential energy surface. Our results therefore reveal chaotic behaviour in the native interaction between ultracold atoms.

  2. 40 CFR 266.107 - Standards to control hydrogen chloride (HCl) and chlorine gas (Cl2) emissions.

    Science.gov (United States)

    2010-07-01

    ... (HCl) and chlorine gas (Cl2) emissions. 266.107 Section 266.107 Protection of Environment ENVIRONMENTAL... Industrial Furnaces § 266.107 Standards to control hydrogen chloride (HCl) and chlorine gas (Cl2) emissions. (a) General. The owner or operator must comply with the hydrogen chloride (HCl) and chlorine (Cl2...

  3. Collisions of electrons with hydrogen atoms I. Package outline and high energy code

    Science.gov (United States)

    Benda, Jakub; Houfek, Karel

    2014-11-01

    Being motivated by the applied researchers' persisting need for accurate scattering data for the collisions of electrons with hydrogen atoms, we developed a computer package-Hex-that is designed to provide trustworthy results for all basic discrete and continuous processes within non-relativistic framework. The package consists of several computational modules that implement different methods, valid for specific energy regimes. Results of the modules are kept in a common database in the unified form of low-level scattering data (partial-wave T-matrices) and accessed by an interface program which is able to produce various derived quantities like e.g. differential and integral cross sections. This article is the first one of a series of articles that are concerned with the implementation and testing of the modules. Here we give an overview of their structure and present (a) the command-line interface program hex-db that can be also easily compiled into a derived code or used as a backend for a web-page form and (b) simple illustrative module specialized for high energies, hex-dwba, that implements distorted and plane wave Born approximation.

  4. Recovery and purification of hydrogen from refinery and petrochemical off-gas streams

    Energy Technology Data Exchange (ETDEWEB)

    Mehra, Y.R.

    1988-04-26

    A process of producing a hydrogen-rich gas product stream as an overhead stream and a rich solvent stream as a bottoms stream from an inlet stream of gas is described comprising hydrogen and hydrocarbon by contacting the inlet hydrogen-containing gas stream with a stream of lean preferential physical solvent in which the hydrocarbons are more soluble and less volatile than hydrogen. The solvent is: A. selected from the group consisting of dialkyl ethers of polyalkylene glycol, N-methyl pyrrolidone, dimethylformamide, propylene carbonate, sulfolane, glycol triacetate, and C/sub 8/ to C/sub 10/ aromatic compounds having methyl, ethyl, propyl, or butyl aliphatic groups specifically constituting a sub-group of mesitylene, n-propyl benzene, n-butyl benzene, cumene, o-xylene m-xylene, p-xylene and mixtures thereof and aromatic streams rich in mixed xylenes, and other C/sub 8/-C/sub 10/ aromatics; and B. selective for methane and heavier hydrocarbon components of the inlet gas stream.

  5. Effect of biologically produced sulfur on gas absorption in a biotechnological hydrogen sulfide removal process

    NARCIS (Netherlands)

    Kleinjan, W.E.; Lammers, J.N.J.J.; Keizer, de A.; Janssen, A.J.H.

    2006-01-01

    Absorption of hydrogen sulfide in aqueous suspensions of biologically produced sulfur particles was studied in a batch stirred cell reactor, and in a continuous set-up, consisting of a lab-scale gas absorber column and a bioreactor. Presence of biosulfur particles was found to enhance the absorption

  6. Microbial Electrolysis Cells for High Yield Hydrogen Gas Production from Organic Matter

    NARCIS (Netherlands)

    Logan, B.E.; Call, D.; Cheng, S.; Hamelers, H.V.M.; Sleutels, T.H.J.A.; Jeremiasse, A.W.; Rozendal, R.A.

    2008-01-01

    The use of electrochemically active bacteria to break down organic matter, combined with the addition of a small voltage (>0.2 V in practice) in specially designed microbial electrolysis cells (MECs), can result in a high yield of hydrogen gas. While microbial electrolysis was invented only a few

  7. ASU nitrogen sweep gas in hydrogen separation membrane for production of HRSG duct burner fuel

    Science.gov (United States)

    Panuccio, Gregory J.; Raybold, Troy M.; Jamal, Agil; Drnevich, Raymond Francis

    2013-04-02

    The present invention relates to the use of low pressure N2 from an air separation unit (ASU) for use as a sweep gas in a hydrogen transport membrane (HTM) to increase syngas H2 recovery and make a near-atmospheric pressure (less than or equal to about 25 psia) fuel for supplemental firing in the heat recovery steam generator (HRSG) duct burner.

  8. Testing of a Hydrogen Diffusion Flame Array Injector at Gas Turbine Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Weiland, Nathan T.; Sidwell, Todd G.; Strakey, Peter A.

    2013-07-03

    High-hydrogen gas turbines enable integration of carbon sequestration into coal-gasifying power plants, though NO{sub x} emissions are often high. This work explores nitrogen dilution of hydrogen diffusion flames to reduce thermal NO{sub x} emissions and avoid problems with premixing hydrogen at gas turbine pressures and temperatures. The burner design includes an array of high-velocity coaxial fuel and air injectors, which balances stability and ignition performance, combustor pressure drop, and flame residence time. Testing of this array injector at representative gas turbine conditions (16 atm and 1750 K firing temperature) yields 4.4 ppmv NO{sub x} at 15% O{sub 2} equivalent. NO{sub x} emissions are proportional to flame residence times, though these deviate from expected scaling due to active combustor cooling and merged flame behavior. The results demonstrate that nitrogen dilution in combination with high velocities can provide low NO{sub x} hydrogen combustion at gas turbine conditions, with significant potential for further NO{sub x} reductions via suggested design changes.

  9. Integration of biohydrogen fermentation and gas separation processes to recover and enrich hydrogen

    NARCIS (Netherlands)

    Bélafi-Bakó, K.; Búcsú, D.; Pientka, Z.; Bálint, B.; Herbel, Z.; Kovács, K.I.; Wessling, Matthias

    2006-01-01

    An integrated system for biohydrogen production and separation was designed, constructed and operated where biohydrogen was fermented by Thermococcus litoralis, a heterotrophic archaebacterium, and a two-step gas separation process was coupled to recover and concentrate hydrogen. A special liquid

  10. Development of a fermentation-based process for biomass conversion to hydrogen gas

    NARCIS (Netherlands)

    Claassen, P.A.M.; Vrije, de G.J.; Urbaniec, K.; Grabarczyk, R.

    2010-01-01

    The production of hydrogen gas from biomass to meet the foreseen demand arising from the expected introduction of fuel cells is envisaged. Apart from the well-known gasification method, fermentative conversion can also be applied for this purpose. Two options of the latter method, that is,

  11. Life Cycle Assessment of Hydrogen Production via Natural Gas Steam Reforming

    Energy Technology Data Exchange (ETDEWEB)

    Spath, P. L.; Mann, M. K.

    2000-09-28

    A life cycle assessment of hydrogen production via natural gas steam reforming was performed to examine the net emissions of greenhouse gases as well as other major environmental consequences. LCA is a systematic analytical method that helps identify and evaluate the environmental impacts of a specific process or competing processes.

  12. Rapid hydrogen gas generation using reactive thermal decomposition of uranium hydride.

    Energy Technology Data Exchange (ETDEWEB)

    Kanouff, Michael P.; Van Blarigan, Peter; Robinson, David B.; Shugard, Andrew D.; Gharagozloo, Patricia E.; Buffleben, George M.; James, Scott Carlton; Mills, Bernice E.

    2011-09-01

    Oxygen gas injection has been studied as one method for rapidly generating hydrogen gas from a uranium hydride storage system. Small scale reactors, 2.9 g UH{sub 3}, were used to study the process experimentally. Complimentary numerical simulations were used to better characterize and understand the strongly coupled chemical and thermal transport processes controlling hydrogen gas liberation. The results indicate that UH{sub 3} and O{sub 2} are sufficiently reactive to enable a well designed system to release gram quantities of hydrogen in {approx} 2 seconds over a broad temperature range. The major system-design challenge appears to be heat management. In addition to the oxidation tests, H/D isotope exchange experiments were performed. The rate limiting step in the overall gas-to-particle exchange process was found to be hydrogen diffusion in the {approx}0.5 {mu}m hydride particles. The experiments generated a set of high quality experimental data; from which effective intra-particle diffusion coefficients can be inferred.

  13. Carbon dioxide emission in hydrogen production technology from coke oven gas with life cycle approach

    Directory of Open Access Journals (Sweden)

    Burmistrz Piotr

    2016-01-01

    Full Text Available The analysis of Carbon Footprint (CF for technology of hydrogen production from cleaned coke oven gas was performed. On the basis of real data and simulation calculations of the production process of hydrogen from coke gas, emission indicators of carbon dioxide (CF were calculated. These indicators are associated with net production of electricity and thermal energy and direct emission of carbon dioxide throughout a whole product life cycle. Product life cycle includes: coal extraction and its transportation to a coking plant, the process of coking coal, purification and reforming of coke oven gas, carbon capture and storage. The values were related to 1 Mg of coking blend and to 1 Mg of the hydrogen produced. The calculation is based on the configuration of hydrogen production from coke oven gas for coking technology available on a commercial scale that uses a technology of coke dry quenching (CDQ. The calculations were made using ChemCAD v.6.0.2 simulator for a steady state of technological process. The analysis of carbon footprint was conducted in accordance with the Life Cycle Assessment (LCA.

  14. Transient flow in pipelines of high-pressure hydrogen-natural gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Elaoud, Sami; Hadj-Taieb, Ezzeddine [Unit of Applied Fluid Mechanics and Modeling, ENIS, Sokra Road Km 4, P.O. Box W, Sfax 3038 (Tunisia)

    2008-09-15

    The purpose of this study is the numerical modeling of high-pressure transient flow of hydrogen-natural gas mixtures in rigid pipelines. The governing equations for such flows are two coupled, non-linear, hyperbolic, partial differential equations. The fluid pressure and velocity are considered as two principal dependent variables. The fluid is a homogeneous hydrogen-natural gas mixture for which the density is defined by an expression averaging the two gas densities where a polytropic process is admitted for the two components. The hydrogen-mixture mass ratio (or quality), assumed to be constant, is used in the mathematical formulation, instead of the void fraction which varies with pressure. The problem has been solved by the non-linear method of characteristics and the finite difference conservative method. To verify their validity, the computed results of the two numerical methods are compared for different values of the quality. The occurrence of pressure oscillations in hydrogen-natural gas mixture pipelines was studied as a result of the compression wave created by a rapid closure of downstream shut-off valve. (author)

  15. Photoluminescence and hydrogen gas-sensing properties of titanium dioxide nanostructures synthesized by hydrothermal treatments

    CSIR Research Space (South Africa)

    Sikhwivhilu, LM

    2012-03-01

    Full Text Available -1 ACS Appl. Mater. Interfaces 2012, 4, 1656-1665 dx.doi.org/10.1021/am2018089 Photoluminescence and Hydrogen Gas-Sensing Properties of Titanium Dioxide Nanostructures Synthesized by Hydrothermal Treatments Lucky M. Sikhwivhilu, Siyasanga Mpelane...

  16. Impact of pH on hydrogen oxidizing redox processes in aquifers due to gas intrusions

    Science.gov (United States)

    Metzgen, Adrian; Berta, Marton; Dethlefsen, Frank; Ebert, Markus; Dahmke, Andreas

    2017-04-01

    Hydrogen production from excess energy and its storage can help increasing the efficiency of solar and wind in the energy mix. Therefore, hydrogen needs large-scale intermediate storage independent of the intended later use as hydrogen gas or as reactant to produce methane in the Sabatier process. A possible storage solution is using the geological subsurface such as caverns built in salt deposits or aquifers that are not used for drinking water production. However, underground storage of hydrogen gas potentially leads to accidental gas leakages into near-surface potable aquifers triggering subsequent geochemical processes. These leakages pose potential risks that are currently not sufficiently understood. To close this gap in knowledge, a high-pressure laboratory column system was used to simulate a hydrogen gas intrusion into a shallow aquifer. Water and sediment were gained from a sandy Pleistocene aquifer near Neumünster, Germany. In the first stage of the experiment, 100% hydrogen gas was used to simulate dissolved hydrogen concentrations between 800 and 4000 µM by varying pH2 between 2 and 15 bars. pH values rose to between 7.9 and 10.4, partly due to stripping CO2 from the groundwater used during H2 gas addition. In a second stage, the pH was regulated in a range of 6.7 to 7.9 by using a gas mixture of 99% H2 and 1% CO2 at 5 bars of total gas pressure. Observed processes included hydrogen oxidation, sulfate reduction, acetogenesis, formate production, and methanogenesis, which were independent of the hydrogen concentration. Hydrogen oxidation and sulfate reduction showed zeroth order reaction rates and rate constants (106 to 412 µM/h and 12 to 33 µM/h, respectively) in the pH range between 8 and 10. At pH levels between 7 and 8, both reactions started out faster near the column's inflow but then seemed limited towards the columns outflow, suggesting the dependence of sulfate reduction on the pH-value. Acetogenesis dominated the pH range between 8 and 10

  17. Heat and mass transfer rates during flow of dissociated hydrogen gas over graphite surface

    Science.gov (United States)

    Nema, V. K.; Sharma, O. P.

    1986-01-01

    To improve upon the performance of chemical rockets, the nuclear reactor has been applied to a rocket propulsion system using hydrogen gas as working fluid and a graphite-composite forming a part of the structure. Under the boundary layer approximation, theoretical predictions of skin friction coefficient, surface heat transfer rate and surface regression rate have been made for laminar/turbulent dissociated hydrogen gas flowing over a flat graphite surface. The external stream is assumed to be frozen. The analysis is restricted to Mach numbers low enough to deal with the situation of only surface-reaction between hydrogen and graphite. Empirical correlations of displacement thickness, local skin friction coefficient, local Nusselt number and local non-dimensional heat transfer rate have been obtained. The magnitude of the surface regression rate is found low enough to ensure the use of graphite as a linear or a component of the system over an extended period without loss of performance.

  18. Generation of hydrogen rich gas through fluidized bed gasification of biomass.

    Science.gov (United States)

    Karmakar, M K; Datta, A B

    2011-01-01

    The objective of this study was to investigate the process of generating hydrogen rich syngas through thermo chemical fluidized bed gasification of biomass. The experiments were performed in a laboratory scale externally heated biomass gasifier. Rice husk had been taken as a representative biomass and, steam had been used as the fluidizing and gasifying media. A thermodynamic equilibrium model was used to predict the gasification process. The work included the parametric study of process parameters such as reactor temperature and steam biomass ratio which generally influence the percentage of hydrogen content in the product gas. Steam had been used here to generate nitrogen free product gas and also to increase the hydrogen concentration in syngas with a medium range heating value of around 12 MJ/Nm3. Copyright © 2010 Elsevier Ltd. All rights reserved.

  19. Rapid analysis of urinary opiates using fast gas chromatography–mass spectrometry and hydrogen as a carrier gas

    Directory of Open Access Journals (Sweden)

    Sumandeep Rana

    2014-09-01

    Gas chromatographic–mass spectrometric analysis was performed in electron ionization mode by selective ion monitoring, using hydrogen as a carrier gas, a short narrow bore GC capillary column, and fast temperature program, allowing for a rapid analytical cycle to maximize the instrument time for high throughput laboratories. While maintaining specificity for these drugs, concentrations in human urine ranging from 50 to 5,000 ng/mL can be measured with intraday and interday imprecision, expressed as variation coefficients, of less than 2.3% for all analytes within a run time of less than 3.5 minutes.

  20. Highly Adsorptive, MOF-Functionalized Nonwoven Fiber Mats for Hazardous Gas Capture Enabled by Atomic Layer Deposition

    Science.gov (United States)

    2014-03-20

    areas and high adsorptive capacities. We find that a nanoscale coating of Al2O3 formed by atomic layer deposition (ALD) on the surface of nonwoven ...distribution is unlimited. Highly Adsorptive, MOF-Functionalized Nonwoven Fiber Mats for Hazardous Gas Capture Enabled by Atomic Layer Deposition The... Nonwoven Fiber Mats for Hazardous Gas Capture Enabled by Atomic Layer Deposition Report Title While metal-organic frameworks (MOFs) show great

  1. The hydrogen gas clearance method for liver blood flow examination: inhalation or local application of hydrogen?

    Science.gov (United States)

    Metzger, H P

    1989-01-01

    The combined method of hydrogen inhalation and local hydrogen production enable the determination of hepatic blood flow (HBF) and local hepatic blood flow (LHBF). LHBF was registered within a small superficial tissue volume of 0.5 mm in diameter by means of a multi-wire electrode having 200 microns producing and 100 microns measuring wires arranged within less than 300 microns distance between the measuring wires. The feeding current for hydrogen production was 1 microA, the potential less than 10 V. The clearance in response to inhalation was registered by means of the same measuring electrodes within the same tissue volume. Spontaneously breathing rats (Wistar-Frömter strain, 180-230 g bw, N = 19, ketamin-xylazine anesthesia, artificial respiration) showed the following flow values: HBF +/- SD = 0.50 +/- 0.26 ml/g.min, n = 48 registrations; LHBF +/- SD = 4.66 +/- 2.13 ml/g.min, n = 43. The validity of the combined method is demonstrated in the LHBF/HBF graph which summarizes the data of hemorrhagic and control animals, m = 0.1 and yo = 0.001. The correlation coefficient of r = 0.685 shows a reasonable correlation of the combined data despite the wide scattering of the individual values.

  2. Atomic data on inelastic processes in low-energy manganese-hydrogen collisions

    Science.gov (United States)

    Belyaev, Andrey K.; Voronov, Yaroslav V.

    2017-10-01

    Aims: The aim of this paper is to calculate cross sections and rate coefficients for inelastic processes in low-energy Mn + H and Mn+ + H- collisions, especially, for processes with high and moderate rate coefficients. These processes are required for non-local thermodynamic equilibrium (non-LTE) modeling of manganese spectra in cool stellar atmospheres, and in particular, for metal-poor stars. Methods: The calculations of the cross sections and the rate coefficients were performed by means of the quantum model approach within the framework of the Born-Oppenheimer formalism, that is, the asymptotic semi-empirical method for the electronic MnH molecular structure calculation followed by the nonadiabatic nuclear dynamical calculation by means of the multichannel analytic formulas. Results: The cross sections and the rate coefficients for low-energy inelastic processes in manganese-hydrogen collisions are calculated for all transitions between 21 low-lying covalent states and one ionic state. We show that the highest values of the cross sections and the rate coefficients correspond to the mutual neutralization processes into the final atomic states Mn(3d54s(7S)5s e 6S), Mn(3d54s(7S)5p y 8P°), Mn(3d54s(7S)5s e 8S), Mn(3d54s(7S)4d e 8D) [the first group], the processes with the rate coefficients (at temperature T = 6000 K) of the values 4.38 × 10-8, 2.72 × 10-8, 1.98 × 10-8, and 1.59 × 10-8 cm3/ s, respectively, that is, with the rate coefficients exceeding 10-8 cm3/ s. The processes with moderate rate coefficients, that is, with values between 10-10 and 10-8 cm3/ s include many excitation, de-excitation, mutual neutralization and ion-pair formation processes. In addition to other processes involving the atomic states from the first group, the processes from the second group include those involving the following atomic states: Mn(3d5(6S)4s4p (1P°) y 6P°), Mn(3d54s(7S)4d e 6D), Mn(3d54s(7S)5p w 6P°), Mn(3d5(4P)4s4p (3P°) y 6D°), Mn(3d5(4G)4s4p (3P°) y 6F

  3. Tank designs for combined high pressure gas and solid state hydrogen storage

    DEFF Research Database (Denmark)

    Mazzucco, Andrea

    Many challenges have still to be overcome in order to establish a solid ground for significant market penetration of fuel cell hydrogen vehicles. The development of an effective solution for on-board hydrogen storage is one of the main technical tasks that need to be tackled. The present thesis...... for each storage solution investigated in this work. Attention is given to solutions that involve high-pressure solid-state and gas hydrogen storage with an integrated passive cooling system. A set of libraries is implemented in the modeling platform to select among different material compositions, kinetic...... compressed-hydrogen vessel respectively. For the former, these models are used to quantify the main design parameter, being the critical metal hydride thickness, for the tank/heat-exchanger system. For the metal hydride tank, the tubular layout in a shell and tube configuration with 2 mm inner diameter tubes...

  4. Stability of MOF-5 in a hydrogen gas environment containing fueling station impurities

    DEFF Research Database (Denmark)

    Ming, Yang; Purewal, Justin; Yang, Jun

    2016-01-01

    Metal-organic frameworks (MOFs) are an emerging class of porous, crystalline materials with potential application as hydrogen storage media in fuel cell vehicles. Unlike lower capacity adsorbents such as zeolites and carbons, some MOFs are expected to degrade due to attack by impurities present...... in the hydrogen fuel stream. Hydrogen intended for use in fuel cell vehicles should satisfy purity standards, such as those outlined in SAE J2719. This standard limits the concentration of certain species in the fuel stream based primarily on their deleterious effects on PEM fuel cells. However, the impact...... of these contaminants on MOFs is mostly unknown. In the present study MOF-5 is adopted as a prototypical moisture-sensitive hydrogen storage material. Five “impure” gas mixtures were prepared by introducing low-to-moderate levels (i.e., up to ∼200 times greater than the J2719 limit) of selected contaminants (NH3, H2S...

  5. Electrochemical atomic layer deposition of Pt nanostructures on fuel cell gas diffusion layer

    CSIR Research Space (South Africa)

    Modibedi, M

    2010-12-01

    Full Text Available the electrochemical activity towards hydrogen, methanol and CO adsorption. ? Deposition time will be optimised. ? Carbon paper will be modified with a conductive microporous layer (Carbon black + Nafion ionomer) before the electrodeposition step. ? Fabricate... cell gas diffusion layer Mmalewane Modibedi1, Tumaini Mkwizu1, 2, Nikiwe Kunjuzwa1,3 , Kenneth Ozoemena1 and Mkhulu Mathe1 1. Energy and Processes, Materials Science and Manufacturing, The Council for Scientific and Industrial Research (CSIR...

  6. 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...

  7. Relationship between the variations of hydrogen in HCNG fuel and the oxygen in exhausted gas

    Directory of Open Access Journals (Sweden)

    Preecha Yaom

    2015-09-01

    Full Text Available The variation of the mixing ratio between hydrogen and compressed natural gas (CNG in hydrogen enriched compressed natural gas fuel (HCNG gives different results in terms of engine performances, fuel consumption, and emission characteristics. Therefore, the engine performance using HCNG as fuel can be optimized if the mixing ratio between the two fuels in HCNG can be adjusted in real time while the engine is being operated. In this research, the relationship between the amount of oxygen in the exhausted gas and the mixing composition between the hydrogen and CNG in HCNG is investigated based on the equilibrium equation of combustion. It is found that the main factors affecting the amount of oxygen in exhausted gas when using HCNG as fuel include the error from the air-fuel-ratio (AFR control, the error from the HCNG composition control, and the intended change of the HCNG composition. Theoretically, the amount of the oxygen in the exhaust should increase by 0.78% for every 5% addition of H2 at stoichiometric condition. This value can be higher or lower for lean and rich engine operation, respectively. The experimental results found that at the equivalent ratio around 0.8 the amount of O2 in the exhaust gas increases about 1.23% for every 5% H2 addition, which inclines with the proposed calculations.

  8. Exergy and thermoeconomic evaluation of hydrogen production from natural gas; Avaliacao exergetica e termo-economica da producao de hidrogenio a partir do gas natural

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Flavio Eduardo da [PROMON Engenharia Ltda., Sao Paulo, SP (Brazil); Oliveira Junior, Silvio de [Universidade de Sao Paulo (USP), SP (Brazil). Escola Politecnica

    2008-07-01

    Some specific processes are required to obtain pure hydrogen and the most usual one is the natural gas reforming, where natural gas reacts with superheated steam producing H{sub 2}, CO, CO{sub 2} and H{sub 2}O. This paper presents exergy and thermoeconomic analysis of a complete hydrogen production unit of a petroleum refinery. The hydrogen production unit analysed in this paper has to supply 550,000 Nm{sup 3} of hydrogen per day to purify diesel oil. Based on a synthesis plant of the hydrogen production unit, the exergy efficiency of each component and of the overall plant are calculated. The hydrogen production cost is determined by means of a thermoeconomic analysis in which the equality cost partition method is employed, including capital and operational costs, in order to determine the production cost of hydrogen and other products of the plant.(author)

  9. Temperature-dependent kinetics of charge transfer, hydrogen-atom transfer, and hydrogen-atom expulsion in the reaction of CO+ with CH4 and CD4.

    Science.gov (United States)

    Melko, Joshua J; Ard, Shaun G; Johnson, Ryan S; Shuman, Nicholas S; Guo, Hua; Viggiano, Albert A

    2014-09-18

    We have determined the rate constants and branching ratios for the reactions of CO(+) with CH4 and CD4 in a variable-temperature selected ion flow tube. We find that the rate constants are collisional for all temperatures measured (193-700 K for CH4 and 193-500 K for CD4). For the CH4 reaction, three product channels are identified, which include charge transfer (CH4(+) + CO), H-atom transfer (HCO(+) + CH3), and H-atom expulsion (CH3CO(+) + H). H-atom transfer is slightly preferred to charge transfer at low temperature, with the charge-transfer product increasing in contribution as the temperature is increased (H-atom expulsion is a minor product for all temperatures). Analogous products are identified for the CD4 reaction. Density functional calculations on the CO(+) + CH4 reaction were also conducted, revealing that the relative temperature dependences of the charge-transfer and H-atom transfer pathways are consistent with an initial charge transfer followed by proton transfer.

  10. Low temperature catalytic combustion of natural gas - hydrogen - air mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Newson, E.; Roth, F. von; Hottinger, P.; Truong, T.B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The low temperature catalytic combustion of natural gas - air mixtures would allow the development of no-NO{sub x} burners for heating and power applications. Using commercially available catalysts, the room temperature ignition of methane-propane-air mixtures has been shown in laboratory reactors with combustion efficiencies over 95% and maximum temperatures less than 700{sup o}C. After a 500 hour stability test, severe deactivation of both methane and propane oxidation functions was observed. In cooperation with industrial partners, scaleup to 3 kW is being investigated together with startup dynamics and catalyst stability. (author) 3 figs., 3 refs.

  11. Two-step high-resolution laser spectroscopy of the Stark substates of the n = 33 level in atomic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Delsart, C.; Cabaret, L.; Blondel, C.; Champeau, R.J.

    1987-09-28

    Two synchronised pulsed single-mode tunable laser systems are used to excite atomic hydrogen in an atomic beam. A vacuum ultraviolet laser populates first the 2p /sup 2/Psub(3/2) sublevel from the ground 1s/sup 2/Ssub(1/2) state. A second-step UV laser selects substates of the n = 33 manifold in the presence of a weak electric field. Stark patterns of this manifold are recorded for different polarisation configurations of the exciting light beams. The measured relative intensities of the Stark components agree with the theoretical excitation probabilities in the two-step process, calculated to the first order of perturbation theory. Varying the field value of the ionisation field pulse also makes it possible to plot the ionisation threshold against the parabolic quantum number in the n = 33 manifold. The results agree with an asymptotic formula of ionisation probabilities for hydrogen perturbed by an electric field.

  12. Selective Hydrogen Sulphide Removal from Acid Gas by Alkali Chemisorption in a Jet Reactor

    Directory of Open Access Journals (Sweden)

    Bobek Janka

    2016-10-01

    Full Text Available Natural gas is a primary energy source that contains a number of light paraffins. It also contains several undesirable components, such as water, ammonia, hydrogen sulphide, etc. In our study, a selective hydrogen sulphide removal process was achieved by alkali chemisorption in a custom-designed jet reactor. Several model gas compositions (CO2-H2S-N2 were evaluated to find parameters that enable H2S absorption instead of CO2. The negative effect of the presence of CO2 in the raw gas on the efficiency of H2S removal was observed. The beneficial effect of the low residence time (less than 1 s on the efficiency of H2S removal was recognized. Optimal operational parameters were defined to reach at least a 50% efficiency of H2S removal and minimal alkali consumption.

  13. Integration of phase change materials in compressed hydrogen gas systems: Modelling and parametric analysis

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rothuizen, Erasmus; Jørgensen, Jens-Erik

    2016-01-01

    A dynamic fueling model is built to simulate the fueling process of a hydrogen tank with an integrated passive cooling system. The study investigates the possibility of absorbing a part of the heat of compression in the high latent-heat material during melting, with the aim of saving the monetary...... and energy resources spent at the refueling station to cool the gas prior to tank filling. This is done while respecting the technical constraint of keeping the walls below the critical temperature of 85 C to ensure the mechanical stability of the storage system even when the gas is fueled at ambient...... temperature. Results show that a 10-mm-thick layer of paraffin wax can absorb enough heat to reduce the adiabatic temperature by 20 K when compared to a standard Type IV tank, but its influence on the hydrogen peak temperature that occurs at the end of refueling is modest. The heat transfer from the gas...

  14. Investigation of Atomic Physics and Frequency Stability with a Croygenic Hydrogen Laser

    National Research Council Canada - National Science Library

    Walsworth, Ronald

    1997-01-01

    .... The cryogenic hydrogen maser (CHM) operates at low temperatures, and may provide frequency stability that is one to three orders of magnitude better than a room temperature hydrogen maser because of greatly reduced thermal noise and larger signal power...

  15. Kinetics of reduction of a RuO2(110) film on Ru by atomic hydrogen

    NARCIS (Netherlands)

    Ugur, D.; Storm, A.J.; Verberk, R.; Brouwer, J.C.; Sloof, W.G.

    2013-01-01

    The kinetics and the mechanism of reduction of a RuO2(110) film, grown thermally on a Ru(0001) surface, has been studied in the temperature range of 60-200 °C by using an atomic hydrogen flux of 2 × 1019 at. H m-2 s-1. The reduction kinetics is dominated by the creation of oxygen vacancies at the

  16. Wave-function Visualization of Core-induced Interaction of Non-hydrogenic Rydberg Atom in Electric Field

    CERN Document Server

    Gao, W; Cheng, H; Zhang, S S; Liu, H P

    2015-01-01

    We have investigated the wave-function feature of Rydberg sodium in a uniform electric field and found that the core-induced interaction of non-hydrogenic atom in electric field can be directly visualized in the wave-function. As is well known, the hydrogen atom in electric field can be separated in parabolic coordinates (\\eta, \\xi), whose eigen-function can show a clear pattern towards negative and positive directions corresponding to the so-called red and blue states without ambiguity, respectively. It can be served as a complete orthogonal basis set to study the core-induced interaction of non-hydrogenic atom in electric field. Owing to complete different patterns of the probability distribution for red and blue states, the interaction can be visualized in the wave-function directly via superposition. Moreover, the constructive and destructive interferences between red and blue states are also observed in the wave-function, explicitly explaining the experimental measurement for the spectral oscillator stre...

  17. Chemical Reactivity Dynamics and Quantum Chaos in Highly Excited Hydrogen Atoms in an External Field: A Quantum Potential Approach

    Directory of Open Access Journals (Sweden)

    B. Maiti

    2002-04-01

    Full Text Available Abstract: Dynamical behavior of chemical reactivity indices like electronegativity, hardness, polarizability, electrophilicity and nucleophilicity indices is studied within a quantum fluid density functional framework for the interactions of a hydrogen atom in its ground electronic state (n = 1 and an excited electronic state (n = 20 with monochromatic and bichromatic laser pulses. Time dependent analogues of various electronic structure principles like the principles of electronegativity equalization, maximum hardness, minimum polarizability and maximum entropy have been found to be operative. Insights into the variation of intensities of the generated higher order harmonics on the color of the external laser field are obtained. The quantum signature of chaos in hydrogen atom has been studied using a quantum theory of motion and quantum fluid dynamics. A hydrogen atom in the electronic ground state (n = 1 and in an excited electronic state ( n = 20 behaves differently when placed in external oscillating monochromatic and bichromatic electric fields. Temporal evolutions of Shannon entropy, quantum Lyapunov exponent and Kolmogorov – Sinai entropy defined in terms of the distance between two initially close Bohmian trajectories for these two cases show marked differences. It appears that a larger uncertainty product and a smaller hardness value signal a chaotic behavior.

  18. Gas-phase hydrogenation/hydrogenolysis of phenol over supported nickel catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Shin, E.J.; Keane, M.A.

    2000-04-01

    The gas-phase hydrogenation/hydrogenolysis of alcoholic solutions of phenol between 423 and 573 K has been studied using a Y zeolite-supported nickel catalyst (2.2% w/w Ni) and Ni/SiO{sub 2} catalysts (1.5--20.3% w/w Ni). This is a viable means of treating concentrated phenol streams to generate recyclable raw material. Phenol hydrogenation proceeded in a stepwise fashion with cyclohexanone as a reactive intermediate while a combination of hydrogenolysis and hydrogenation yielded cyclohexane. Hydrogenolysis to benzene is favored by high nickel loadings and elevated temperatures. A catalytic hydrogen treatment of cyclohexanone and cyclohexanol helped to establish the overall reaction network/mechanism. The possible role of thermodynamic limitations is considered and structure sensitivity is addressed; reaction data are subjected to a pseudo-first-order kinetic treatment. Hydrogen temperature-programmed desorption (H{sub 2}-TPD) has revealed the existence of different forms of surface hydrogen. Selectivity is interpreted on the basis of the H{sub 2}-TPD profiles and the possible phenol/catalyst interactions. The zeolite sample only catalyzed (via the surface Bronsted acidity) anisole formation in the presence of methanol, but this was suppressed when hexanol was used; the zeolite then promoted hydrogenolysis. The zeolite, however, deactivated and this was not reversed by heating in hydrogen. The results of the hydrogen treatment of aqueous rather than alcoholic phenol solutions are presented, where a switch from methanol to water was accompanied by a move from highly selective hydrogenolysis to highly selective hydrogenation.

  19. Thermodynamics of various F420 coenzyme models as sources of electrons, hydride ions, hydrogen atoms and protons in acetonitrile.

    Science.gov (United States)

    Xia, Ke; Shen, Guang-Bin; Zhu, Xiao-Qing

    2015-06-14

    32 F420 coenzyme models with alkylation of the three different N atoms (N1, N3 and N10) in the core structure (XFH(-)) were designed and synthesized and the thermodynamic driving forces (defined in terms of the molar enthalpy changes or the standard redox potentials in this work) of the 32 XFH(-) releasing hydride ions, hydrogen atoms and electrons, the thermodynamic driving forces of the 32 XFH˙ releasing protons and hydrogen atoms and the thermodynamic driving forces of XF(-)˙ releasing electrons in acetonitrile were determined using titration calorimetry and electrochemical methods. The effects of the methyl group at N1, N3 and N10 and a negative charge on N1 and N10 atoms on the six thermodynamic driving forces of the F420 coenzyme models and their related reaction intermediates were examined; the results show that seating arrangements of the methyl group and the negative charge have remarkably different effects on the thermodynamic properties of the F420 coenzyme models and their related reaction intermediates. The effects of the substituents at C7 and C8 on the six thermodynamic driving forces of the F420 coenzyme models and their related reaction intermediates were also examined; the results show that the substituents at C7 and C8 have good Hammett linear free energy relationships with the six thermodynamic parameters. Meanwhile, a reasonable determination of possible reactions between members of the F420 family and NADH family in vivo was given according to a thermodynamic analysis platform constructed using the elementary step thermodynamic parameter of F420 coenzyme model 2FH(-) and NADH model MNAH releasing hydride ions in acetonitrile. The information disclosed in this work can not only fill a gap in the chemical thermodynamics of F420 coenzyme models as a class of very important organic sources of electrons, hydride ions, hydrogen atoms and protons, but also strongly promote the fast development of the chemistry and applications of F420 coenzyme.

  20. Hydrogen Gas Ameliorates Hepatic Reperfusion Injury After Prolonged Cold Preservation in Isolated Perfused Rat Liver.

    Science.gov (United States)

    Shimada, Shingo; Wakayama, Kenji; Fukai, Moto; Shimamura, Tsuyoshi; Ishikawa, Takahisa; Fukumori, Daisuke; Shibata, Maki; Yamashita, Kenichiro; Kimura, Taichi; Todo, Satoru; Ohsawa, Ikuroh; Taketomi, Akinobu

    2016-12-01

    Hydrogen gas reduces ischemia and reperfusion injury (IRI) in the liver and other organs. However, the precise mechanism remains elusive. We investigated whether hydrogen gas ameliorated hepatic I/R injury after cold preservation. Rat liver was subjected to 48-h cold storage in University of Wisconsin solution. The graft was reperfused with oxygenated buffer with or without hydrogen at 37° for 90 min on an isolated perfusion apparatus, comprising the H2 (+) and H2 (-) groups, respectively. In the control group (CT), grafts were reperfused immediately without preservation. Graft function, injury, and circulatory status were assessed throughout the perfusion. Tissue samples at the end of perfusion were collected to determine histopathology, oxidative stress, and apoptosis. In the H2 (-) group, IRI was indicated by a higher aspartate aminotransferase (AST), alanine aminotransferase (ALT) leakage, portal resistance, 8-hydroxy-2-deoxyguanosine-positive cell rate, apoptotic index, and endothelial endothelin-1 expression, together with reduced bile production, oxygen consumption, and GSH/GSSG ratio (vs. CT). In the H2 (+) group, these harmful changes were significantly suppressed [vs. H2 (-)]. Hydrogen gas reduced hepatic reperfusion injury after prolonged cold preservation via the maintenance of portal flow, by protecting mitochondrial function during the early phase of reperfusion, and via the suppression of oxidative stress and inflammatory cascades thereafter. Copyright © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  1. Hydrogen gas inhalation inhibits progression to the "irreversible" stage of shock after severe hemorrhage in rats.

    Science.gov (United States)

    Matsuoka, Tadashi; Suzuki, Masaru; Sano, Motoaki; Hayashida, Kei; Tamura, Tomoyoshi; Homma, Koichiro; Fukuda, Keiichi; Sasaki, Junichi

    2017-09-01

    Mortality of hemorrhagic shock primarily depends on whether or not the patients can endure the loss of circulating volume until radical treatment is applied. We investigated whether hydrogen (H2) gas inhalation would influence the tolerance to hemorrhagic shock and improve survival. Hemorrhagic shock was achieved by withdrawing blood until the mean arterial blood pressure reached 30-35 mm Hg. After 60 minutes of shock, the rats were resuscitated with a volume of normal saline equal to four times the volume of shed blood. The rats were assigned to either the H2 gas (1.3% H2, 26% O2, 72.7% N2)-treated group or the control gas (26% O2, 74% N2)-treated group. Inhalation of the specified gas mixture began at the initiation of blood withdrawal and continued for 2 hours after fluid resuscitation. The survival rate at 6 hours after fluid resuscitation was 80% in H2 gas-treated rats and 30% in control gas-treated rats (p gas-treated rats than in the control rats. Despite losing more blood, the increase in serum potassium levels was suppressed in the H2 gas-treated rats after 60 minutes of shock. Fluid resuscitation completely restored blood pressure in the H2 gas-treated rats, whereas it failed to fully restore the blood pressure in the control gas-treated rats. At 2 hours after fluid resuscitation, blood pressure remained in the normal range and metabolic acidosis was well compensated in the H2 gas-treated rats, whereas we observed decreased blood pressure and uncompensated metabolic acidosis and hyperkalemia in the surviving control gas-treated rats. H2 gas inhalation delays the progression to irreversible shock. Clinically, H2 gas inhalation is expected to stabilize the subject until curative treatment can be performed, thereby increasing the probability of survival after hemorrhagic shock.

  2. Integration of phase change materials in compressed hydrogen gas systems: Modelling and parametric analysis

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rothuizen, Erasmus; Jørgensen, Jens-Erik

    2016-01-01

    A dynamic fueling model is built to simulate the fueling process of a hydrogen tank with an integrated passive cooling system. The study investigates the possibility of absorbing a part of the heat of compression in the high latent-heat material during melting, with the aim of saving the monetary...... temperature. Results show that a 10-mm-thick layer of paraffin wax can absorb enough heat to reduce the adiabatic temperature by 20 K when compared to a standard Type IV tank, but its influence on the hydrogen peak temperature that occurs at the end of refueling is modest. The heat transfer from the gas...

  3. A compressed hydrogen gas storage system with an integrated phase change material

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rothuizen, Erasmus Damgaard; Jørgensen, Jens Erik

    2015-01-01

    A dynamic fueling model is built to simulate the fueling process of a hydrogen tank with an integrated passive cooling system. The study investigates the possibility of absorbing a part of the heat of compression in the high latent-heat material during melting, with the aim of keeping the walls...... below the critical temperature of 85 °C, while filling the hydrogen at ambient temperature. Results show that a 10-mm-thick layer of paraffin wax can absorb enough heat to reduce the adiabatic temperature by 20 K when compared to a standard Type IV tank. The heat transfer from the gas to the phase...

  4. Robust, Reliable Low Emission Gas Turbine Combustion of High Hydrogen Content Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Wooldridge, Margaret Stacy [Univ. of Michigan, Ann Arbor, MI (United States); Im, Hong Geum [Univ. of Michigan, Ann Arbor, MI (United States)

    2016-12-16

    The effects of high hydrogen content fuels were studied using experimental, computational and theoretical approaches to understand the effects of mixture and state conditions on the ignition behavior of the fuels. A rapid compression facility (RCF) was used to measure the ignition delay time of hydrogen and carbon monoxide mixtures. The data were combined with results of previous studies to develop ignition regime criteria. Analytical theory and direct numerical simulation were used to validate and interpret the RCF ignition data. Based on the integrated information the ignition regime criteria were extended to non-dimensional metrics which enable application of the results to practical gas turbine combustion systems.

  5. Neutral hydrogen (H I) gas content of galaxies at z ≈ 0.32

    Science.gov (United States)

    Rhee, Jonghwan; Lah, Philip; Briggs, Frank H.; Chengalur, Jayaram N.; Colless, Matthew; Willner, Steven P.; Ashby, Matthew L. N.; Le Fèvre, Olivier

    2018-01-01

    We use observations made with the Giant Metrewave Radio Telescope (GMRT) to probe the neutral hydrogen (H I) gas content of field galaxies in the VIMOS VLT Deep Survey (VVDS) 14h field at z ≈ 0.32. Because the H I emission from individual galaxies is too faint to detect at this redshift, we use an H I spectral stacking technique using the known optical positions and redshifts of the 165 galaxies in our sample to co-add their H I spectra and thus obtain the average H I mass of the galaxies. Stacked H I measurements of 165 galaxies show that ≳ 95 per cent of the neutral gas is found in blue, star-forming galaxies. Among these galaxies, those having lower stellar mass are more gas rich than more massive ones. We apply a volume correction to our H I measurement to evaluate the H I gas density at z ≈ 0.32 as Ω_{H I}=(0.50± 0.18)× 10^{-3} in units of the cosmic critical density. This value is in good agreement with previous results at z < 0.4, suggesting no evolution in the neutral hydrogen gas density over the last ∼4 Gyr. However the z ≈ 0.32 gas density is lower than that at z ∼ 5 by at least a factor of two.

  6. Benchmark Calculation of Radial Expectation Value \\varvec{< r^{-2} \\rangle } for Confined Hydrogen-Like Atoms and Isotropic Harmonic Oscillators

    Science.gov (United States)

    Yu, Rong Mei; Zan, Li Rong; Jiao, Li Guang; Ho, Yew Kam

    2017-09-01

    Spatially confined atoms have been extensively investigated to model atomic systems in extreme pressures. For the simplest hydrogen-like atoms and isotropic harmonic oscillators, numerous physical quantities have been established with very high accuracy. However, the expectation value of which is of practical importance in many applications has significant discrepancies among calculations by different methods. In this work we employed the basis expansion method with cut-off Slater-type orbitals to investigate these two confined systems. Accurate values for several low-lying bound states were obtained by carefully examining the convergence with respect to the size of basis. A scaling law for was derived and it is used to verify the accuracy of numerical results. Comparison with other calculations show that the present results establish benchmark values for this quantity, which may be useful in future studies.

  7. Selection of a Gaussian basis set for calculating the Bethe logarithm for the ground state of the hydrogen atom

    Science.gov (United States)

    Stanke, Monika; Adamowicz, Ludwik; Kedziera, Dariusz

    2013-07-01

    The inclusion of the leading quantum electrodynamic energy correction is unavoidable if one aims for sub 0.01 cm-1 accuracy in the calculations of atomic and molecular spectra. The important part of the calculation of the correction is the determination of the value of the so-called Bethe logarithm (ln k 0). In this work, we examine how to construct Gaussian basis sets for such calculations. While the testing is performed for the ground state of the hydrogen atom, the results allow us to suggest how the construction of appropriate basis sets can be handled in ln k 0 calculations of atoms and molecules with more than one electron performed with explicitly correlated all-electron Gaussian functions.

  8. Inactivation of animal and human prions by hydrogen peroxide gas plasma sterilization.

    Science.gov (United States)

    Rogez-Kreuz, C; Yousfi, R; Soufflet, C; Quadrio, I; Yan, Z-X; Huyot, V; Aubenque, C; Destrez, P; Roth, K; Roberts, C; Favero, M; Clayette, P

    2009-08-01

    Prions cause various transmissible spongiform encephalopathies. They are highly resistant to the chemical and physical decontamination and sterilization procedures routinely used in healthcare facilities. The decontamination procedures recommended for the inactivation of prions are often incompatible with the materials used in medical devices. In this study, we evaluated the use of low-temperature hydrogen peroxide gas plasma sterilization systems and other instrument-processing procedures for inactivating human and animal prions. We provide new data concerning the efficacy of hydrogen peroxide against prions from in vitro or in vivo tests, focusing on the following: the efficiency of hydrogen peroxide sterilization and possible interactions with enzymatic or alkaline detergents, differences in the efficiency of this treatment against different prion strains, and the influence of contaminating lipids. We found that gaseous hydrogen peroxide decreased the infectivity of prions and/or the level of the protease-resistant form of the prion protein on different surface materials. However, the efficiency of this treatment depended strongly on the concentration of hydrogen peroxide and the delivery system used in medical devices, because these effects were more pronounced for the new generation of Sterrad technology. The Sterrad NX sterilizer is 100% efficient (0% transmission and no protease-resistant form of the prion protein signal detected on the surface of the material for the mouse-adapted bovine spongiform encephalopathy 6PB1 strain and a variant Creutzfeldt-Jakob disease strain). Thus, gaseous or vaporized hydrogen peroxide efficiently inactivates prions on the surfaces of medical devices.

  9. Monte Carlo methods: Application to hydrogen gas and hard spheres

    Science.gov (United States)

    Dewing, Mark Douglas

    2001-08-01

    Quantum Monte Carlo (QMC) methods are among the most accurate for computing ground state properties of quantum systems. The two major types of QMC we use are Variational Monte Carlo (VMC), which evaluates integrals arising from the variational principle, and Diffusion Monte Carlo (DMC), which stochastically projects to the ground state from a trial wave function. These methods are applied to a system of boson hard spheres to get exact, infinite system size results for the ground state at several densities. The kinds of problems that can be simulated with Monte Carlo methods are expanded through the development of new algorithms for combining a QMC simulation with a classical Monte Carlo simulation, which we call Coupled Electronic-Ionic Monte Carlo (CEIMC). The new CEIMC method is applied to a system of molecular hydrogen at temperatures ranging from 2800K to 4500K and densities from 0.25 to 0.46 g/cm3. VMC requires optimizing a parameterized wave function to find the minimum energy. We examine several techniques for optimizing VMC wave functions, focusing on the ability to optimize parameters appearing in the Slater determinant. Classical Monte Carlo simulations use an empirical interatomic potential to compute equilibrium properties of various states of matter. The CEIMC method replaces the empirical potential with a QMC calculation of the electronic energy. This is similar in spirit to the Car-Parrinello technique, which uses Density Functional Theory for the electrons and molecular dynamics for the nuclei. The challenges in constructing an efficient CEIMC simulation center mostly around the noisy results generated from the QMC computations of the electronic energy. We introduce two complementary techniques, one for tolerating the noise and the other for reducing it. The penalty method modifies the Metropolis acceptance ratio to tolerate noise without introducing a bias in the simulation of the nuclei. For reducing the noise, we introduce the two-sided energy

  10. Hydrogen Gas Inhalation Attenuates Seawater Instillation-Induced Acute Lung Injury via the Nrf2 Pathway in Rabbits.

    Science.gov (United States)

    Diao, Mengyuan; Zhang, Sheng; Wu, Lifeng; Huan, Le; Huang, Fenglou; Cui, Yunliang; Lin, Zhaofen

    2016-12-01

    Seawater instillation-induced acute lung injury involves oxidative stress and apoptosis. Although hydrogen gas inhalation is reportedly protective in multiple types of lung injury, the effect of hydrogen gas inhalation on seawater instillation-induced acute lung injury remains unknown. This study investigated the effect of hydrogen gas on seawater instillation-induced acute lung injury and explored the mechanisms involved. Rabbits were randomly assigned to control, hydrogen (2 % hydrogen gas inhalation), seawater (3 mL/kg seawater instillation), and seawater + hydrogen (3 mL/kg seawater instillation + 2 % hydrogen gas inhalation) groups. Arterial partial oxygen pressure and lung wet/dry weight ratio were detected. Protein content in bronchoalveolar lavage fluid (BALF) and serum as well as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 levels were determined. Hematoxylin-eosin staining was used to monitor changes in lung specimens, and malondialdehyde (MDA) content and myeloperoxidase (MPO) activity were assayed. In addition, NF-E2-related factor (Nrf) 2 and heme oxygenase (HO)-1 mRNA and protein expression were measured, and apoptosis was assessed by measuring caspase-3 expression and using terminal deoxy-nucleotidyl transferase dUTP nick end-labeling (TUNEL) staining. Hydrogen gas inhalation markedly improved lung endothelial permeability and decreased both MDA content and MPO activity in lung tissue; these changes were associated with decreases in TNF-α, IL-1β, and IL-6 in BALF. Hydrogen gas also alleviated histopathological changes and cell apoptosis. Moreover, Nrf2 and HO-1 expressions were significantly activated and caspase-3 expression was inhibited. These results demonstrate that hydrogen gas inhalation attenuates seawater instillation-induced acute lung injury in rabbits and that the protective effects observed may be related to the activation of the Nrf2 pathway.

  11. Hydrogen production by absorption enhanced water gas shift (AEWGS)

    Energy Technology Data Exchange (ETDEWEB)

    Escobedo Bretado, Miguel A. [Facultad de Ciencias Quimicas, Universidad Juarez del Estado de Durango, Ave. Veterinaria s/n, Circuito Universitario, Durango 34120 (Mexico); Departamento de Quimica de Materiales, Centro de Investigacion en Materiales Avanzados, S.C. Miguel de Cervantes 120, Chihuahua, Chih. 31109 (Mexico); Delgado Vigil, Manuel D.; Gutierrez, Jesus Salinas; Lopez Ortiz, Alejandro; Collins-Martinez, Virginia [Departamento de Quimica de Materiales, Centro de Investigacion en Materiales Avanzados, S.C. Miguel de Cervantes 120, Chihuahua, Chih. 31109 (Mexico)

    2010-11-15

    AEWGS is a reaction that combines the WGS reaction and CO{sub 2} capture by a solid absorbent to produce high purity H{sub 2} from synthesis gas in one single step at 600-800 C. This reactor system, if homogeneous, would not require a catalyst. However, previous research on this concept was not conclusive, since a steel reactor was used and reactor walls were suspected to act as catalyst. Therefore, there is a need to address this issue and to select and evaluate suitable CO{sub 2} absorbents for this concept. AEWGS was studied using a quartz-made fixed-bed reactor at; SV = 3000 h{sup -1}, feed; 5% CO, 15% H{sub 2}O, balance He-N{sub 2} at 600 C, 1 atm. CO{sub 2} absorbents tested were CaO*MgO, and Na{sub 2}ZrO{sub 3}. Empty quartz-reactor tests leaded to conclude that a catalyst is needed for the WGS at temperatures of interest. A 97% H{sub 2} product was obtained with calcined dolomite suggesting this last to act as a WGS catalyst. (author)

  12. Effectiveness of oxygen enriched hydrogen-HHO gas addition on DI diesel engine performance, emission and combustion characteristics

    Directory of Open Access Journals (Sweden)

    Premkartikkumar S.R.

    2014-01-01

    Full Text Available Nowadays, more researches focus on protecting the environment. Present investigation concern with the effectiveness of Oxygen Enriched hydrogen- HHO gas addition on performance, emission and combustion characteristics of a DI diesel engine. Here the Oxygen Enriched hydrogen-HHO gas was produced by the process of water electrolysis. When potential difference is applied across the anode and cathode electrodes of the electrolyzer, water is transmuted into Oxygen Enriched hydrogen-HHO gas. The produced gas was aspirated into the cylinder along with intake air at the flow rates of 1 lpm and 3.3 lpm. The results show that when Oxygen Enriched hydrogen-HHO gas was inducted, the brake thermal efficiency of the engine increased by 11.06%, Carbon monoxide decreased by 15.38%, Unburned hydrocarbon decreased by 18.18%, Carbon dioxide increased by 6.06%, however, the NOX emission increased by 11.19%.

  13. Determining air quality and greenhouse gas impacts of hydrogen infrastructure and fuel cell vehicles.

    Science.gov (United States)

    Stephens-Romero, Shane; Carreras-Sospedra, Marc; Brouwer, Jacob; Dabdub, Donald; Samuelsen, Scott

    2009-12-01

    Adoption of hydrogen infrastructure and hydrogen fuel cell vehicles (HFCVs) to replace gasoline internal combustion engine (ICE) vehicles has been proposed as a strategy to reduce criteria pollutant and greenhouse gas (GHG) emissions from the transportation sector and transition to fuel independence. However, it is uncertain (1) to what degree the reduction in criteria pollutants will impact urban air quality, and (2) how the reductions in pollutant emissions and concomitant urban air quality impacts compare to ultralow emission gasoline-powered vehicles projected for a future year (e.g., 2060). To address these questions, the present study introduces a "spatially and temporally resolved energy and environment tool" (STREET) to characterize the pollutant and GHG emissions associated with a comprehensive hydrogen supply infrastructure and HFCVs at a high level of geographic and temporal resolution. To demonstrate the utility of STREET, two spatially and temporally resolved scenarios for hydrogen infrastructure are evaluated in a prototypical urban airshed (the South Coast Air Basin of California) using geographic information systems (GIS) data. The well-to-wheels (WTW) GHG emissions are quantified and the air quality is established using a detailed atmospheric chemistry and transport model followed by a comparison to a future gasoline scenario comprised of advanced ICE vehicles. One hydrogen scenario includes more renewable primary energy sources for hydrogen generation and the other includes more fossil fuel sources. The two scenarios encompass a variety of hydrogen generation, distribution, and fueling strategies. GHG emissions reductions range from 61 to 68% for both hydrogen scenarios in parallel with substantial improvements in urban air quality (e.g., reductions of 10 ppb in peak 8-h-averaged ozone and 6 mug/m(3) in 24-h-averaged particulate matter concentrations, particularly in regions of the airshed where concentrations are highest for the gasoline scenario).

  14. Adiabatic Variational Theory for Cold Atom-Molecule Collisions: Application to a Metastable Helium Atom Colliding with ortho- and para-Hydrogen Molecules.

    Science.gov (United States)

    Pawlak, Mariusz; Shagam, Yuval; Klein, Ayelet; Narevicius, Edvardas; Moiseyev, Nimrod

    2017-03-16

    We recently developed an adiabatic theory for cold molecular collision experiments. In our previous application of this theory ( Pawlak, M.; et al. J. Chem. Phys. 2015 , 143 , 074114 ), we assumed that during the experiment the collision of an atom with a diatom takes place when the diatom is in the ground rotational state and is located in a plane. In this paper, we present how the variational approach of the adiabatic theory for low-temperature collision experiments can be used for the study a 5D collision between the atom and the diatomic molecule with no limitations on its rotational quantum states and no plane restrictions. Moreover, we show here the dramatic differences in the measured reaction rates of He(23S1) + ortho/para-H2 → He(1s2) + ortho/para-H2+ + e- resulting from the anisotropic long-range interactions in the reaction. In collisions of metastable helium with molecular hydrogen in the ground rotational state, the isotropic potential term dominates the dynamics. When the collision is with molecular hydrogen in the first excited rotational state, the nonisotropic interactions play an important role in the dynamics. The agreement of our results with the latest experimental findings ( Klein , A. ; et al. Nat. Phys. 2017 , 13 , 35 - 38 ) is very good.

  15. A Measurement of the Rate of Muon Capture in Hydrogen Gas andDetermination of the Proton's Induced Pseudoscalar Coupling gP

    Energy Technology Data Exchange (ETDEWEB)

    Banks, Thomas Ira [Univ. of California, Berkeley, CA (United States)

    2007-07-01

    This dissertation describes a measurement of the rate ofnuclear muon capture by the proton, performed by the MuCap Collaborationusing a new technique based on a time projection chamber operating inultraclean, deuterium-depleted hydrogen gas at room temperature and 1 MPapressure. The hydrogen target's low gas density of 1 percent compared toliquid hydrogen is key to avoiding uncertainties that arise from theformation of muonic molecules. The capture rate was obtained from thedifference between the μ- disappearance rate in hydrogen--as determinedfrom data collected in the experiment's first physics run in fall2004--and the world averagefor the μ+ decay rate. After combining theresults of my analysis with the results from another independent analysisof the 2004 data, the muon capture rate from the hyperfine singlet groundstate of the mu-p atom is found to be ΛS = 725.0 ± 17.4 1/s, fromwhich the induced pseudoscalar coupling of the nucleon, gP(q2 = -0.88m$2\\atop{μ}$)= 7.3 ± 1.1, is extracted. This result for gP is consistent withtheoretical predictions that are based on the approximate chiral symmetryof QCD.

  16. Comparative investigation of pure and mixed rare gas atoms on coronene molecules.

    Science.gov (United States)

    Rodríguez-Cantano, Rocío; Bartolomei, Massimiliano; Hernández, Marta I; Campos-Martínez, José; González-Lezana, Tomás; Villarreal, Pablo; Pérez de Tudela, Ricardo; Pirani, Fernando; Hernández-Rojas, Javier; Bretón, José

    2017-01-21

    Clusters formed by the combination of rare gas (RG) atoms of He, Ne, Ar, and Kr on coronene have been investigated by means of a basin-hopping algorithm and path integral Monte Carlo calculations at T = 2 K. Energies and geometries have been obtained and the role played by the specific RG-RG and RG-coronene interactions on the final results is analysed in detail. Signatures of diffuse behavior of the He atoms on the surface of the coronene are in contrast with the localization of the heavier species, Ar and Kr. The observed coexistence of various geometries for Ne suggests the motion of the RG atoms on the multi-well potential energy surface landscape offered by the coronene. Therefore, the investigation of different clusters enables a comparative analysis of localized versus non-localized features. Mixed Ar-He-coronene clusters have also been considered and the competition of the RG atoms to occupy the docking sites on the molecule is discussed. All the obtained information is crucial to assess the behavior of coronene, a prototypical polycyclic aromatic hydrocarbon clustering with RG atoms at a temperature close to that of interstellar medium, which arises from the critical balance of the interactions involved.

  17. Quasi-metallic behavior of ZnO grown by atomic layer deposition: The role of hydrogen

    Science.gov (United States)

    Beh, Holger; Hiller, Daniel; Bruns, Michael; Welle, Alexander; Becker, Hans-Werner; Berghoff, Birger; Sürgers, Christoph; Merz, Rolf; Zacharias, Margit

    2017-07-01

    Zinc oxide (ZnO) fabricated by atomic layer deposition (ALD) is intrinsically well-conductive (˜5 mΩ cm), in contrast to the single-crystalline bulk material or sputtered ZnO thin films. There are generally three groups of candidates for the intrinsic n-type conductivity: intrinsic point defects, elemental impurities other than hydrogen, and incorporated hydrogen itself. In this study, we assess the different candidates concerning their impact on conductivity. In the presence of free electron densities of up to 5 × 1019 cm-3, impurities other than hydrogen are ruled out due to their ultra-low concentrations in the ppm range. Intrinsic point defects are also considered unlikely since the evolution of conductivity with deposition temperature is not reproduced in the Zn/O ratio as measured by Rutherford backscattering spectrometry. Hence, the most promising candidate is hydrogen with a concentration of ˜1 at. %, i.e., more than sufficient to account for the free electron density. In addition, we find a correlation between the deposition-temperature dependence of the carrier concentration and the hydrogen concentration. The formation energy of the conductive, hydrogen-related state is determined to be ˜40 meV. Hall measurements down to liquid helium temperatures revealed that the electron densities are constant over the whole temperature range. This constitutes a quasi-metallic behavior of ALD-ZnO for deposition temperatures of ≥150 °C. We propose that the very high concentration of hydrogen-induced donor states causes a vanishing ionization energy so that the donor band merges energetically with the ZnO conduction band. This model is supported by ultraviolet photoelectron spectroscopy measurements.

  18. On physical nanoscale aspects of compatibility of steels with hydrogen and natural gas.

    Science.gov (United States)

    Nechaev, Yu S; Ochsner, A

    2010-02-01

    The possibilities of effective solutions of relevant technological problems are considered based on the analysis of fundamental physical aspects, elucidation of the nano-structural mechanisms and interrelations of aging and hydrogen embrittlement of materials (steels) in the hydrogen industry and gas-main industries. The adverse effects which these mechanisms and processes have on the service properties and technological lifetime of materials are analyzed. The concomitant fundamental process of formation of carbohydride-like and other segregation nanostructures at dislocations (with the segregation capacity 1 to 1.5 orders of magnitude greater than in the widely used Cottrell 'atmosphere' model) and grain boundaries is discussed in the context of how these nanostructures affect technological processes (aging, hydrogen embrittlement, stress corrosion damage, and failure) and the physicomechanical properties of the metallic materials (including the technological lifetimes of pipeline steels).

  19. The Reaction between Sodium Hydroxide and Atomic Hydrogen in Atmospheric and Flame Chemistry.

    Science.gov (United States)

    Gómez Martín, J C; Seaton, C; de Miranda, M P; Plane, J M C

    2017-10-12

    We report the first direct kinetic study of the gas-phase reaction NaOH + H → Na + H2O, which is central to the chemistry of sodium in the upper atmosphere and in flames. The reaction was studied in a fast flow tube, where NaOH was observed by multiphoton ionization and time-of-flight mass spectrometry, yielding k(NaOH + H, 230-298 K) = (3.8 ± 0.8) × 10(-11) cm(3) molecule (-1) s(-1) (at 2σ confidence level), showing no significant temperature dependence over the indicated temperature range and essentially in agreement with previous estimates of the rate constant in hydrogen-rich flames. We show, using theoretical trajectory calculations, that the unexpectedly slow, yet T-independent, rate coefficient for NaOH + H is explained by severe constraints in the angle of attack that H can make on NaOH to produce H2O. This reaction is also central to explaining Na-catalyzed flame inhibition, which has been proposed to occur via the sequence Na + OH (+ M) → NaOH followed by NaOH + H → Na + H2O, thereby effectively recombinating H and OH to H2O. RRKM calculations for the recombination of Na and OH yield k(Na + OH + N2, 300-2400 K) = 2.7 × 10(-29) (300/T)(1.2) cm(6) molecule(-2) s(-1), in agreement with a previous flash photolysis measurement at 653 K and Na-seeded flame studies in the 1800-2200 K range. These results therefore provide strong evidence to support the mechanism of flame inhibition by Na.

  20. Chromatographic measurement of hydrogen isotopic and permanent gas impurities in tritium

    Energy Technology Data Exchange (ETDEWEB)

    Warner, D.K.; Kinard, C.; Bohl, D.C.

    1976-06-04

    This paper describes a gas chromatograph that was designed for dedicated analysis of hydrogen isotopic and permanent gas impurities in tritium and tritium-deuterium mixtures. The instrument that was developed substantially improved the accuracy and precision of hydrogen isotopic analysis in the 20 ppM to one mole percent range as compared with other analytical methods. Several unique design features of the instrument were required due to the radiation and isotopic exchange properties of the tritium in the samples; descriptions of these features are presented along with details of the complete chromatographic system. The experimental procedures used to calibrate the detector and statistically evaluate its performance are given, and the sources of analytical error are cited. The limitations of the present system are also discussed.