WorldWideScience

Sample records for gas phase excitation

  1. Ultrafast electronic relaxation of excited state vitamin B12 in the gas phase

    International Nuclear Information System (INIS)

    Shafizadeh, Niloufar; Poisson, Lionel; Soep, Benoit

    2008-01-01

    The time evolution of electronically excited vitamin B 12 (cyanocobalamin) has been observed for the first time in the gas phase. It reveals an ultrafast decay to a state corresponding to metal excitation. This decay is interpreted as resulting from a ring to metal electron transfer. This opens the observation of the excited state of other complex biomimetic systems in the gas phase, the key to the characterisation of their complex evolution through excited electronic states

  2. Modeling pulsed excitation for gas-phase laser diagnostics

    International Nuclear Information System (INIS)

    Settersten, Thomas B.; Linne, Mark A.

    2002-01-01

    Excitation dynamics for pulsed optical excitation are described with the density-matrix equations and the rate equations for a two-level system. A critical comparison of the two descriptions is made with complete and consistent formalisms that are amenable to the modeling of applied laser-diagnostic techniques. General solutions, resulting from numerical integration of the differential equations describing the excitation process, are compared for collisional conditions that range from the completely coherent limit to the steady-state limit, for which the two formalisms are identical. This analysis demonstrates the failure of the rate equations to correctly describe the transient details of the excitation process outside the steady-state limit. However, reasonable estimates of the resultant population are obtained for nonsaturating (linear) excitation. This comparison provides the laser diagnostician with the means to evaluate the appropriate model for excitation through a simple picture of the breakdown of the rate-equation validity

  3. Ultrafast excited-state relaxation of a binuclear Ag(i) phosphine complex in gas phase and solution.

    Science.gov (United States)

    Kruppa, S V; Bäppler, F; Klopper, W; Walg, S P; Thiel, W R; Diller, R; Riehn, C

    2017-08-30

    The binuclear complex [Ag 2 (dcpm) 2 ](PF 6 ) 2 (dcpm = bis(dicyclohexylphosphino)methane) exhibits a structure with a close silver-silver contact mediated by the bridging ligand and thus a weak argentophilic interaction. Upon electronic excitation this cooperative effect is strongly increased and determines the optical and luminescence properties of the compound. We have studied here the ultrafast electronic dynamics in parallel in gas phase by transient photodissociation and in solution by transient absorption. In particular, we report the diverse photofragmentation pathways of isolated [Ag 2 (dcpm) 2 ] 2+ in an ion trap and its gas phase UV photodissociation spectrum. By pump-probe fragmentation action spectroscopy (λ ex = 260 nm) in the gas phase, we have obtained fragment-specific transients which exhibit a common ultrafast multiexponential decay. This is fitted to four time constants (0.6/5.8/100/>1000 ps), highlighting complex intrinsic photophysical processes. Remarkably, multiexponential dynamics (0.9/8.5/73/604 ps) are as well found for the relaxation dynamics in acetonitrile solution. Ab initio calculations at the level of approximate coupled-cluster singles-doubles (CC2) theory of ground and electronically excited states of the reduced model system [Ag 2 (dmpm) 2 ] 2+ (dmpm = bis(dimethylphosphino)methane) indicate a shortening of the Ag-Ag distance upon excitation by 0.3-0.4 Å. In C 2 geometry two close-lying singlet states S 1 ( 1 MC(dσ*-pπ), 1 B, 4.13 eV) and S 2 ( 1 MC(dσ*-pσ), 1 A, 4.45 eV) are found. The nearly dark S 1 state has not been reported so far. The excitation of the S 2 state carries a large oscillator strength for the calculated vertical transition (266 nm). Two related triplets are calculated at T 1 (3.87 eV) and T 2 (3.90 eV). From these findings we suggest possible relaxation pathways with the two short time constants ascribed to ISC/IVR and propose from the obtained similar values in gas phase that the fast solution dynamics

  4. An opsin shift in rhodopsin: retinal S0-S1 excitation in protein, in solution, and in the gas phase.

    Science.gov (United States)

    Bravaya, Ksenia; Bochenkova, Anastasia; Granovsky, Alexander; Nemukhin, Alexander

    2007-10-31

    We considered a series of model systems for treating the photoabsorption of the 11-cis retinal chromophore in the protonated Schiff-base form in vacuum, solutions, and the protein environment. A high computational level, including the quantum mechanical-molecular mechanical (QM/MM) approach for solution and protein was utilized in simulations. The S0-S1 excitation energies in quantum subsystems were evaluated by means of an augmented version of the multiconfigurational quasidegenerate perturbation theory (aug-MCQDPT2) with the ground-state geometry parameters optimized in the density functional theory PBE0/cc-pVDZ approximation. The computed positions of absorption bands lambdamax, 599(g), 448(s), and 515(p) nm for the gas phase, solution, and protein, respectively, are in excellent agreement with the corresponding experimental data, 610(g), 445(s), and 500(p) nm. Such consistency provides a support for the formulated qualitative conclusions on the role of the chromophore geometry, environmental electrostatic field, and the counterion in different media. An essentially nonplanar geometry conformation of the chromophore group in the region of the C14-C15 bond was obtained for the protein, in particular, owing to the presence of the neighboring charged amino acid residue Glu181. Nonplanarity of the C14-C15 bond region along with the influence of the negatively charged counterions Glu181 and Glu113 are found to be important to reproduce the spectroscopic features of retinal chromophore inside the Rh cavity. Furthermore, the protein field is responsible for the largest bond-order decrease at the C11-C12 double bond upon excitation, which may be the reason for the 11-cis photoisomerization specificity.

  5. High excitation ISM and gas

    NARCIS (Netherlands)

    Peeters, E; Martinez-Hernandez, NL; Rodriguez-Fernandez, NJ; Tielens, [No Value

    An overview is given of ISO results on regions of high excitation ISM and gas, i.e. H II regions, the Galactic Centre and Supernova Remnants. IR emission due to fine-structure lines, molecular hydrogen, silicates, polycyclic aromatic hydrocarbons and dust are summarised, their diagnostic

  6. High Excitation Gas and ISM

    Science.gov (United States)

    Peeters, E.; Martin-Hernandez, N. L.; Rodriguez-Fernandez, N. J.; Tielens, A. G. G. M.

    2004-01-01

    An overview is given of ISO results on regions of high excitation ISM and gas, i.e. HII regions, the Galactic Centre and Supernovae Remnants. IR emission due to fine-structure lines, molecular hydrogen, silicates, polycyclic aromatic hydrocarbons and dust are summarized, their diagnostic capabilities illustrated and their implications highlighted.

  7. Excited-state dynamics of a ruthenium(II) catalyst studied by transient photofragmentation in gas phase and transient absorption in solution

    Energy Technology Data Exchange (ETDEWEB)

    Imanbaew, D.; Nosenko, Y. [Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 52–54, 67663 Kaiserslautern (Germany); Forschungszentrum OPTIMAS, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern (Germany); Kerner, C. [Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 52–54, 67663 Kaiserslautern (Germany); Chevalier, K.; Rupp, F. [Fachbereich Physik, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern (Germany); Riehn, C., E-mail: riehn@chemie.uni-kl.de [Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 52–54, 67663 Kaiserslautern (Germany); Forschungszentrum OPTIMAS, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern (Germany); Thiel, W.R. [Fachbereich Chemie, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 52–54, 67663 Kaiserslautern (Germany); Diller, R. [Fachbereich Physik, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern (Germany)

    2014-10-17

    Graphical abstract: - Highlights: • Ultrafast dynamics of new Ru(II) catalysts investigated in gas phase and solution. • Catalyst activation (HCl loss) achieved in ion trap by UV photoexcitation. • Electronic relaxation proceeds by IVR and IC followed by ground state dissociation. • No triplet formation in contrast to other Ru-polypyridine complexes. • Solvent prohibits catalyst activation in solution by fast vibrational cooling. - Abstract: We report studies on the excited state dynamics of new ruthenium(II) complexes [(η{sup 6}-cymene)RuCl(apypm)]PF{sub 6} (apypm=2-NR{sub 2}-4-(pyridine-2-yl)-pyrimidine, R=CH{sub 3} (1)/H (2)) which, in their active form [1{sup +}-HCl] and [2{sup +}-HCl], catalyze the transfer hydrogenation of arylalkyl ketones in the absence of a base. The investigations encompass femtosecond pump–probe transient mass spectrometry under isolated conditions and transient absorption spectroscopy in acetonitrile solution, both on the cations [(η{sup 6}-cymene)RuCl(apypm)]{sup +} (1{sup +}, 2{sup +}). Gas phase studies on mass selected ions were performed in an ESI ion trap mass spectrometer by transient photofragmentation, unambiguously proving the formation of the activated catalyst species [1{sup +}-HCl] or [2{sup +}-HCl] after photoexcitation being the only fragmentation channel. The primary excited state dynamics in the gas phase could be fitted to a biexponential decay, yielding time constants of <100 fs and 1–3 ps. Transient absorption spectroscopy performed in acetonitrile solution using femtosecond UV/Vis and IR probe laser pulses revealed additional deactivation processes on longer time scales (∼7–12 ps). However, the formation of the active catalyst species after photoexcitation could not be observed in solution. The results from both studies are compared to former CID investigations and DFT calculations concerning the activation mechanism.

  8. Gas phase ion chemistry

    CERN Document Server

    Bowers, Michael T

    1979-01-01

    Gas Phase Ion Chemistry, Volume 2 covers the advances in gas phase ion chemistry. The book discusses the stabilities of positive ions from equilibrium gas-phase basicity measurements; the experimental methods used to determine molecular electron affinities, specifically photoelectron spectroscopy, photodetachment spectroscopy, charge transfer, and collisional ionization; and the gas-phase acidity scale. The text also describes the basis of the technique of chemical ionization mass spectrometry; the energetics and mechanisms of unimolecular reactions of positive ions; and the photodissociation

  9. Electron-beam-excited gas laser research

    International Nuclear Information System (INIS)

    Johnson, A.W.; Gerardo, J.B.; Patterson, E.L.; Gerber, R.A.; Rice, J.K.; Bingham, F.W.

    1975-01-01

    Net energy gain in laser fusion places requirements on the laser that are not realized by any existing laser. Utilization of relativistic electron beams (REB's), a relatively new source for the excitation of gas laser media, may lead to new lasers that could satisfy these requirements. Already REB's have been utilized to excite gas laser media and produce gas lasers that have not been produced as successfully any other way. Electron-beam-excitation has produced electronic-transition dimer lasers that have not yet been produced by any other excitation scheme (for example, Xe 2 / sup *(1)/, Kr:O(2 1 S)/sup 2/, KrF/sup *(3)/). In addition, REB's have initiated chemical reactions to produce HF laser radiation with unique and promising results. Relativistic-electron-beam gas-laser research is continuing to lead to new lasers with unique properties. Results of work carried out at Sandia Laboratories in this pioneering effort of electron-beam-excited-gas lasers are reviewed. (U.S.)

  10. Gas Phase Nanoparticle Synthesis

    Science.gov (United States)

    Granqvist, Claes; Kish, Laszlo; Marlow, William

    This book deals with gas-phase nanoparticle synthesis and is intended for researchers and research students in nanomaterials science and engineering, condensed matter physics and chemistry, and aerosol science. Gas-phase nanoparticle synthesis is instrumental to nanotechnology - a field in current focus that raises hopes for environmentally benign, resource-lean manufacturing. Nanoparticles can be produced by many physical, chemical, and even biological routes. Gas-phase synthesis is particularly interesting since one can achieve accurate manufacturing control and hence industrial viability.

  11. Multipurpose exciter with low phase noise

    Science.gov (United States)

    Conroy, B.; Le, D.

    1989-01-01

    Results of an effort to develop a lower-cost exciter with high stability, low phase noise, and controllable phase and frequency for use in Deep Space Network and Goldstone Solar System Radar applications are discussed. Included is a discussion of the basic concept, test results, plans, and concerns.

  12. Elementary excitations and phase transformations in solids

    International Nuclear Information System (INIS)

    Cowley, R.A.

    1985-01-01

    Neutron scattering is and will continue to be a uniquely powerful tool for the study of elementary excitations and phase transformations in solids. The paper examines a few recent experiments on molecular crystals, superionic materials, paramagnetic scattering and phase transitions to see what experimental features made these experiments possible, and hence to make suggestions about future needs. It is concluded that new instruments will extend the scope of neutron scattering studies to new excitations, that there is a need for higher resolution, particularly for phase transition studies, and that it will be important to use intensity information, discrimination against unwanted inelastic processes and polarization analysis to reliably measure the excitations in new materials. (author)

  13. Gas phase ion chemistry

    CERN Document Server

    Bowers, Michael T

    1979-01-01

    Gas Phase Ion Chemistry, Volume 1 covers papers on the advances of gas phase ion chemistry. The book discusses the advances in flow tubes and the measurement of ion-molecule rate coefficients and product distributions; the ion chemistry of the earth's atmosphere; and the classical ion-molecule collision theory. The text also describes statistical methods in reaction dynamics; the state selection by photoion-photoelectron coincidence; and the effects of temperature and pressure in the kinetics of ion-molecule reactions. The energy distribution in the unimolecular decomposition of ions, as well

  14. Gas phase pulse radiolysis

    International Nuclear Information System (INIS)

    Jonah, C.D.; Andong Liu; Mulac, W.A.

    1987-01-01

    Gas phase pulse radiolysis, a technique which can be used to study many different phenomena in chemistry and physics, is discussed. As a source of small radicals, pulse radiolysis is important to the field of chemistry, particularly to combustion and atmospheric kinetics. The reactions of 1,3-butadiene, allene, ethylene and acetylene with OH are presented. 52 refs., 1 fig., 1 tab

  15. Gas-Phase Thermolyses

    DEFF Research Database (Denmark)

    Carlsen, Lars; Egsgaard, Helge

    1982-01-01

    The unimolecular gas-phase thermolyses of 1,2,3-oxadithiolan 2-oxide and thiiran 1-oxide have been studied by the flash vacuum thermolysis–field ionization mass spectrometry (f.v.t.–f.i.m.s.) technique in the temperature range from 1 043 to 1 404 K. The reactions are rationalized in terms of sulp...

  16. Gas-Phase Thermolyses

    DEFF Research Database (Denmark)

    Carlsen, Lars; Egsgaard, Helge

    1982-01-01

    The unimolecular gas-phase thermolyses of the four methyl and ethyl monothioacetates (5)–(8) have been studied by the flash vacuum thermolysis–field ionization mass spectrometry technique in the temperature range 883–1 404 K. The types of reactions verified were keten formation, thiono–thiolo rea...

  17. Gas-Phase Thermolysis

    DEFF Research Database (Denmark)

    Carlsen, Lars; Egsgaard, Helge; Schaumann, Ernst

    1980-01-01

    The unimolecular gas-phase thermolytic decomposition of three silylated thionocarboxylic acid derivatives (2b), (3), and (8) have been studied by the flash vacuum thermolysis–field ionization mass spectrometry technique in the temperature range from 783 to 1 404 K in order to elucidate its possible...... applicability as a route to thioketens. Only very minor amounts of the expected thioketens were found, whereas the corresponding ketens were obtained as the major products. A possible mechanism for keten formation is discussed....

  18. HBr Formation from the Reaction between Gas-phase Bromine Atom and Vibrationally Excited Chemisorbed Hydrogen Atoms on a Si(001)-(2 x 1) Surface

    International Nuclear Information System (INIS)

    Ree, J.; Yoon, S. H.; Park, K. G.; Kim, Y. H.

    2004-01-01

    We have calculated the probability of HBr formation and energy disposal of the reaction exothermicity in HBr produced from the reaction of gas-phase bromine with highly covered chemisorbed hydrogen atoms on a Si (001)-(2 x 1) surface. The reaction probability is about 0.20 at gas temperature 1500 K and surface temperature 300 K. Raising the initial vibrational state of the adsorbate(H)-surface(Si) bond from the ground to v = 1, 2 and 3 states causes the vibrational, translational and rotational energies of the product HBr to increase equally. However, the vibrational and translational motions of product HBr share most of the reaction energy. Vibrational population of the HBr molecules produced from the ground state adsorbate-surface bond (vHSi = 0) follows the Boltzmann distribution, but it deviates seriously from the Boltzmann distribution when the initial vibrational energy of the adsorbate-surface bond increases. When the vibration of the adsorbate-surface bond is in the ground state, the amount of energy dissipated into the surface is negative, while it becomes positive as vHSi increases. The energy distributions among the various modes weakly depends on surface temperature in the range of 0-600 K, regardless of the initial vibrational state of H(ad)-Si(s) bond

  19. Excitation power quantities in phase resonance testing of nonlinear systems with phase-locked-loop excitation

    Science.gov (United States)

    Peter, Simon; Leine, Remco I.

    2017-11-01

    Phase resonance testing is one method for the experimental extraction of nonlinear normal modes. This paper proposes a novel method for nonlinear phase resonance testing. Firstly, the issue of appropriate excitation is approached on the basis of excitation power considerations. Therefore, power quantities known from nonlinear systems theory in electrical engineering are transferred to nonlinear structural dynamics applications. A new power-based nonlinear mode indicator function is derived, which is generally applicable, reliable and easy to implement in experiments. Secondly, the tuning of the excitation phase is automated by the use of a Phase-Locked-Loop controller. This method provides a very user-friendly and fast way for obtaining the backbone curve. Furthermore, the method allows to exploit specific advantages of phase control such as the robustness for lightly damped systems and the stabilization of unstable branches of the frequency response. The reduced tuning time for the excitation makes the commonly used free-decay measurements for the extraction of backbone curves unnecessary. Instead, steady-state measurements for every point of the curve are obtained. In conjunction with the new mode indicator function, the correlation of every measured point with the associated nonlinear normal mode of the underlying conservative system can be evaluated. Moreover, it is shown that the analysis of the excitation power helps to locate sources of inaccuracies in the force appropriation process. The method is illustrated by a numerical example and its functionality in experiments is demonstrated on a benchmark beam structure.

  20. Introduction to gas lasers with emphasis on selective excitation processes

    CERN Document Server

    Willett, Colin S

    1974-01-01

    Introduction to Gas Lasers: Population Inversion Mechanisms focuses on important processes in gas discharge lasers and basic atomic collision processes that operate in a gas laser. Organized into six chapters, this book first discusses the historical development and basic principles of gas lasers. Subsequent chapters describe the selective excitation processes in gas discharges and the specific neutral, ionized and molecular laser systems. This book will be a valuable reference on the behavior of gas-discharge lasers to anyone already in the field.

  1. The Ultrafast Wolff Rearrangement in the Gas Phase

    Science.gov (United States)

    Steinbacher, Andreas; Roeding, Sebastian; Brixner, Tobias; Nuernberger, Patrick

    The Wolff rearrangement of gas-phase 5-diazo Meldrum's acid is disclosed with femtosecond ion spectroscopy. Distinct differences are found for 267 nm and 200 nm excitation, the latter leading to even two ultrafast rearrangement reactions.

  2. Physical Improvements in Exciter/Igniter Units, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed Phase 2 project consists of the physical integration of our Phase 1 small, compact exciter with a "flight like" igniter or spark plug capable of...

  3. EPR investigation of electronic excitations in rare gas solids (Review Article)

    Science.gov (United States)

    Zhitnikov, R. A.; Dmitriev, Yu. A.

    1998-10-01

    The methods are described for producing unstable paramagnetic excited states in rare gas cryocrystals Ne, Ar, Kr, and Xe through the trapping, in the cryocrystals growing from the gas phase, the products of the gas discharge taking place in the same or other rare gas. The paper presents a technique and results of an observation and investigation of excited states in rare gas cryocrystals with electron paramagnetic resonance (EPR). The discovered unstable paramagnetic centers are interpreted as being local metastable excited np5(n+1)s atomic-type states in rare gas cryocrystals which are subject to the action of the anisotropic electric field resulted from the crystal surroundings distorted by the center. An account is given of the mechanisms for formation of observed paramagnetic excited states in cryocrystals which arise owing to the excitation energy of the metastable 3P2 atoms of Ne, Ar, Kr, Xe and He 23S1 and 21S0 atoms that form in the discharge in an appropriate gas and trap in the growing cryocrystal.

  4. Comparison of electrical and optical characteristics in gas-phase and gas-liquid phase discharges

    Energy Technology Data Exchange (ETDEWEB)

    Qazi, H. I. A.; Li, He-Ping, E-mail: liheping@tsinghua.edu.cn; Zhang, Xiao-Fei; Bao, Cheng-Yu [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Nie, Qiu-Yue [School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin, Heilongjiang Province 150001 (China)

    2015-12-15

    This paper presents an AC-excited argon discharge generated using a gas-liquid (two-phase) hybrid plasma reactor, which mainly consists of a powered needle electrode enclosed in a conical quartz tube and grounded deionized water electrode. The discharges in the gas-phase, as well as in the two-phase, exhibit two discharge modes, i.e., the low current glow-like diffuse mode and the high current streamer-like constrict mode, with a mode transition, which exhibits a negative resistance of the discharges. The optical emission spectral analysis shows that the stronger diffusion of the water vapor into the discharge region in the two-phase discharges boosts up the generation of OH (A–X) radicals, and consequently, leads to a higher rotational temperature in the water-phase plasma plume than that of the gas-phase discharges. Both the increase of the power input and the decrease of the argon flow rate result in the increase of the rotational temperature in the plasma plume of the water-phase discharge. The stable two-phase discharges with a long plasma plume in the water-phase under a low power input and gas flow rate may show a promising prospect for the degradation of organic pollutants, e.g., printing and dyeing wastewater, in the field of environmental protection.

  5. Reactive intermediates in the gas phase generation and monitoring

    CERN Document Server

    Setser, D W

    2013-01-01

    Reactive Intermediates in the Gas Phase: Generation and Monitoring covers methods for reactive intermediates in the gas phase. The book discusses the generation and measurement of atom and radical concentrations in flow systems; the high temperature flow tubes, generation and measurement of refractory species; and the electronically excited long-lived states of atoms and diatomic molecules in flow systems. The text also describes the production and detection of reactive species with lasers in static systems; the production of small positive ions in a mass spectrometer; and the discharge-excite

  6. Casimir interaction between gas media of excited atoms

    International Nuclear Information System (INIS)

    Sherkunov, Yury

    2007-01-01

    The retarded dispersion interaction (Casimir interaction) between two dilute dielectric media at high temperatures is considered. The excited atoms are taken into account. It is shown that the perturbation technique cannot be applied to this problem due to divergence of integrals. A non-perturbative approach based on kinetic Green functions is implemented. We consider the interaction between two atoms (one of them is excited) embedded in an absorbing dielectric medium. We take into account the possible absorption of photons in the medium, which solves the problem of divergence. The force between two plane dilute dielectric media is calculated at pair interaction approximation. We show that the result of quantum electrodynamics differs from the Lifshitz formula for dilute gas media at high temperatures (if the number of excited atoms is significant). According to quantum electrodynamics, the interaction may be either attractive or repulsive depending on the temperature and the density numbers of the media

  7. Fermionic Collective Excitations in a Lattice Gas of Rydberg Atoms

    International Nuclear Information System (INIS)

    Olmos, B.; Gonzalez-Ferez, R.; Lesanovsky, I.

    2009-01-01

    We investigate the many-body quantum states of a laser-driven gas of Rydberg atoms confined to a large spacing ring lattice. If the laser driving is much stronger than the van der Waals interaction among the Rydberg atoms, these many-body states are collective fermionic excitations. The first excited state is a spin wave that extends over the entire lattice. We demonstrate that our system permits us to study fermions in the presence of disorder although no external atomic motion takes place. We analyze how this disorder influences the excitation properties of the fermionic states. Our work shows a route towards the creation of complex many-particle states with atoms in lattices.

  8. Study on the excited diatomic molecules of rare gas

    International Nuclear Information System (INIS)

    Kasama, Kunihiko; Arai, Shigeyoshi

    1981-01-01

    The study on the excited diatomic molecules of rare gas is presented. The absorption spectra, the mechanism of formation and attenuation and the reactions with other molecules are described. The excitation of rare gas was made by using a pulsed electron beam generator. The absorption of excited diatomic molecules was measured as the functions of time. Two absorption peaks were observed. The electron states of rare gases were estimated. The observed and calculated transition values were given for each peak. The absorption spectra of Ne change with time. The spectra of Ar do not change with time. Four and eleven absorption maxima were seen in the spectra of Kr and Xe, respectively. In the case of Ar, the thermal equilibrium existed. The constants of the production and attenuation rates were obtained as the functions of Ar gas pressure. In the case of Ne, there wad definitely the time dependence of absorption spectra. The attenuation constant was obtained for each transition between various vibration levels. It is necessary to consider the relaxation from high vibrational levels. The energy transfer between vibrational levels hardly occurred in Ne because the intervals are large. When there are other molecules, the attnuation was accelerated. (Kato, T.)

  9. Phased Array Excitations For Efficient Near Field Wireless Power Transmission

    Science.gov (United States)

    2016-09-01

    channeled to the battery or power plant. Figure 2. WPT System Block Diagram for Battery Charging. Source : [2]. Wireless power transfer has gained...EXCITATIONS FOR EFFICIENT NEAR-FIELD WIRELESS POWER TRANSMISSION by Sean X. Hong September 2016 Thesis Advisor: David Jenn Second Reader...TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE PHASED ARRAY EXCITATIONS FOR EFFICIENT NEAR-FIELD WIRELESS POWER TRANSMISSION 5

  10. Pure-Phase Selective Excitation in Fast-Relaxing Systems

    Science.gov (United States)

    Zangger, Klaus; Oberer, Monika; Sterk, Heinz

    2001-09-01

    Selective pulses have been used frequently for small molecules. However, their application to proteins and other macromolecules has been limited. The long duration of shaped-selective pulses and the short T2 relaxation times in proteins often prohibited the use of highly selective pulses especially on larger biomolecules. A very selective excitation can be obtained within a short time by using the selective excitation sequence presented in this paper. Instead of using a shaped low-intensity radiofrequency pulse, a cluster of hard 90° pulses, delays of free precession, and pulsed field gradients can be used to selectively excite a narrow chemical shift range within a relatively short time. Thereby, off-resonance magnetization, which is allowed to evolve freely during the free precession intervals, is destroyed by the gradient pulses. Off-resonance excitation artifacts can be removed by random variation of the interpulse delays. This leads to an excitation profile with selectivity as well as phase and relaxation behavior superior to that of commonly used shaped-selective pulses. Since the evolution of scalar coupling is inherently suppressed during the double-selective excitation of two different scalar-coupled nuclei, the presented pulse cluster is especially suited for simultaneous highly selective excitation of N-H and C-H fragments. Experimental examples are demonstrated on hen egg white lysozyme (14 kD) and the bacterial antidote ParD (19 kD).

  11. Phasing of independent laser channels under impact SBS excitation

    Energy Technology Data Exchange (ETDEWEB)

    Gordeev, A A; Efimkov, V F; Zubarev, I G; Mikhailov, S I [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-10-31

    It is shown experimentally that phasing of independent laser channels under impact SBS excitation calls for a stable difference in arm lengths, as in a classical Michelson interferometer. A scheme with automatic compensation for fluctuations of interferometer arm lengths has been proposed and experimentally implemented. This scheme makes it possible to perform stable phasing of two laser channels under standard laboratory conditions. (control of radiation parameters)

  12. Solid gas reaction phase diagram under high gas pressure

    International Nuclear Information System (INIS)

    Ishizaki, K.

    1992-01-01

    This paper reports that to evaluate which are the stable phases under high gas pressure conditions, a solid-gas reaction phase diagram under high gas pressure (HIP phase diagram) has been proposed by the author. The variables of the diagram are temperature, reactant gas partial pressure and total gas pressure. Up to the present time the diagrams have been constructed using isobaric conditions. In this work, the stable phases for a real HIP process were evaluated assuming an isochoric condition. To understand the effect of the total gas pressure on stability is of primary importance. Two possibilities were considered and evaluated, those are: the total gas pressure acts as an independent variable, or it only affects the fugacity values. The results of this work indicate that the total gas pressure acts as an independent variable, and in turn also affects the fugacity values

  13. Modified random phase approximation for multipole excitations at finite temperature

    International Nuclear Information System (INIS)

    Nguyen Dinh Dang

    1991-01-01

    The modified finite temperature random phase approximation (modified FT-RPA) has been constructed with taking the influence of thermostat on the structure of quansiparticles into account. The modified FT-RPA linear response for electric quadrupole (λ π = 2 + ) and octupole (λ π = 3 - ) excitations in 5 8Ni has been calculated as a function of the nuclear temperature. As compared to the conventional FT-RPA the modified FT-RPA has given a stronger spreading for the strength distribution of quandrupole excitations at finite temperature T ≤ 3MeV. (author). 22 refs; 4 figs; 2 tabs

  14. Excitations and phase transitions in random anti-ferromagnets

    International Nuclear Information System (INIS)

    Cowley, R.A.; Birgeneau, R.J.; Shirane, G.

    1979-01-01

    Neutron scattering techniques can be used to study the magnetic excitations and phase transitions in the randomly mixed transition metal fluorides. The results for the excitations of samples with two different types of magnetic ions show two bands of excitations; each associated with excitations propagating largely on one type of ion. In the diluted salts the spectra show a complex line shape and greater widths. These results are in good accord with computer simulations showing that linear spin wave theory can be used, but have not been described satisfactorily using the coherent potential approximation. The phase transitions in these materials are always smeared, but it is difficult to ascertain if this smearing is due to macroscopic fluctuations in the concentration or of an intrinsic origin. Studies of these systems close to the percolation point have shown that the thermal disorder is associated with the one-dimensional weak links of the large clusters. Currently theory and experiment are in accord for the two-dimensional Ising system but features are still not understood in Heisenberg systems in both two and three dimensions

  15. Superfluid 3He at very low temperatures: a very unusual excitation gas

    International Nuclear Information System (INIS)

    Pickett, G.R.; Enrico, M.P.; Fisher, S.N.; Guenault, A.M.; Torizuka, K.

    1994-01-01

    The excitation gas in superfluid 3 He at low temperatures shows a number of remarkable dynamical properties arising from the unusual dispersion curve. The existence of an energy gap leads to many of the observed properties varying rapidly with temperature, since the excitation density is dominated by the gap Boltzmann factor exp(-Δ/kT). But also, the fact that the minimum energy lies at finite momentum gives rise to Andreev scattering processes, in which the velocity of the excitation is reversed but the momentum left virtually unchanged. Since the dispersion curve looks different to a moving observer, there is the possibility of the free production of quasiparticle-quasihole pairs at a Landau critical velocity. At low temperatures the mean free path becomes much larger than any experimental size. Using vibrating wire resonators as universal probes, we can monitor the temperature, measure the Kapitz resistance, examine the nonlinear regime beyond the two-fluid model, observe the Landau velocity, create and detect thermal beams of excitation with black-body radiators, observe Andreev reflection directly and probe A-phase textures (in which the gas is one-dimensional). Future possibilities are discussed. (orig.)

  16. Iodine removal from a gas phase

    International Nuclear Information System (INIS)

    Vikis, A. Ch.

    1982-01-01

    Iodine, e.g. radioactive iodine, present as one or more organic iodides, optionally with elemental iodine, in a gas phase (e.g. air) are removed by photochemically decomposing the organic iodides to elemental iodine, reacting the iodine produced, and any initially present with excess ozone, preferably photochemically produced in situ in the gas phase to produce solid iodine oxides, and removing the solid oxides from the gas phase. (author)

  17. Iodine removal from a gas phase

    International Nuclear Information System (INIS)

    Vikis, A.C.

    1984-01-01

    Iodine, e.g. radioactive iodine, present as one or more organic iodides, optionally with elemental iodine, in a gas phase (e.g. air) are removed by photochemically decomposing the organic iodides to elemental iodine, reacting the iodine produced, and any initially present with excess ozone, preferably photochemically produced in situ in the gas phase to produce solid iodine oxides, and removing the solid oxides from the gas phase

  18. The liquid to vapor phase transition in excited nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, J.B.; Moretto, L.G.; Phair, L.; Wozniak, G.J.; Beaulieu, L.; Breuer, H.; Korteling, R.G.; Kwiatkowski, K.; Lefort, T.; Pienkowski, L.; Ruangma, A.; Viola, V.E.; Yennello, S.J.

    2001-05-08

    For many years it has been speculated that excited nuclei would undergo a liquid to vapor phase transition. For even longer, it has been known that clusterization in a vapor carries direct information on the liquid-vapor equilibrium according to Fisher's droplet model. Now the thermal component of the 8 GeV/c pion + 197 Au multifragmentation data of the ISiS Collaboration is shown to follow the scaling predicted by Fisher's model, thus providing the strongest evidence yet of the liquid to vapor phase transition.

  19. Excited Atoms and Molecules in High Pressure Gas Discharges

    International Nuclear Information System (INIS)

    Vuskovic, L.; Popovic, S.

    2003-01-01

    Various types of high-pressure non-thermal discharges are increasingly drawing attention in view of many interesting applications. These, partially ionized media in non-equilibrium state, tend to generate complex effects that are difficult to interpret without a detailed knowledge of elementary processes involved. Electronically excited molecules and atoms may play an important role as intermediate states in a wide range of atomic and molecular processes, many of which are important in high-pressure discharges. They can serve also as reservoirs of energy or as sources of high energy electrons either through the energy pooling or through superelastic collisions. By presenting the analysis of current situation on the processes involving excited atoms and molecules of interest for high-pressure gas discharges, we will attempt to draw attention on the insufficiency of available data. In the same time we will show how to circumvent this situation and still be able to develop accurate models and interpretations of the observed phenomena

  20. Penning ionization cross sections of excited rare gas atoms

    International Nuclear Information System (INIS)

    Ukai, Masatoshi; Hatano, Yoshihiko.

    1988-01-01

    Electronic energy transfer processes involving excited rare gas atoms play one of the most important roles in ionized gas phenomena. Penning ionization is one of the well known electronic energy transfer processes and has been studied extensively both experimentally and theoretically. The present paper reports the deexcitation (Penning ionization) cross sections of metastable state helium He(2 3 S) and radiative He(2 1 P) atoms in collision with atoms and molecules, which have recently been obtained by the authors' group by using a pulse radiolysis method. Investigation is made of the selected deexcitation cross sections of He(2 3 S) by atoms and molecules in the thermal collisional energy region. Results indicate that the cross sections are strongly dependent on the target molecule. The deexcitation probability of He(2 3 S) per collision increases with the excess electronic energy of He(2 3 S) above the ionization potential of the target atom or molecule. Another investigation, made on the deexcitation of He(2 1 P), suggests that the deexcitation cross section for He(2 1 P) by Ar is determined mainly by the Penning ionization cross section due to a dipole-dipole interaction. Penning ionization due to the dipole-dipole interaction is also important for deexcitation of He(2 1 P) by the target molecules examined. (N.K.)

  1. Unstable dynamics, nonequilibrium phases, and criticality in networked excitable media

    International Nuclear Information System (INIS)

    Franciscis, S. de; Torres, J. J.; Marro, J.

    2010-01-01

    Excitable systems are of great theoretical and practical interest in mathematics, physics, chemistry, and biology. Here, we numerically study models of excitable media, namely, networks whose nodes may occasionally be dormant and the connection weights are allowed to vary with the system activity on a short-time scale, which is a convenient and realistic representation. The resulting global activity is quite sensitive to stimuli and eventually becomes unstable also in the absence of any stimuli. Outstanding consequences of such unstable dynamics are the spontaneous occurrence of various nonequilibrium phases--including associative-memory phases and one in which the global activity wanders irregularly, e.g., chaotically among all or part of the dynamic attractors--and 1/f noise as the system is driven into the phase region corresponding to the most irregular behavior. A net result is resilience which results in an efficient search in the model attractor space that can explain the origin of some observed behavior in neural, genetic, and ill-condensed matter systems. By extensive computer simulation we also address a previously conjectured relation between observed power-law distributions and the possible occurrence of a ''critical state'' during functionality of, e.g., cortical networks, and describe the precise nature of such criticality in the model which may serve to guide future experiments.

  2. An Introduction to the Gas Phase

    Science.gov (United States)

    Vallance, Claire

    2017-11-01

    'An Introduction to the Gas Phase' is adapted from a set of lecture notes for a core first year lecture course in physical chemistry taught at the University of Oxford. The book is intended to give a relatively concise introduction to the gas phase at a level suitable for any undergraduate scientist. After defining the gas phase, properties of gases such as temperature, pressure, and volume are discussed. The relationships between these properties are explained at a molecular level, and simple models are introduced that allow the various gas laws to be derived from first principles. Finally, the collisional behaviour of gases is used to explain a number of gas-phase phenomena, such as effusion, diffusion, and thermal conductivity.

  3. Forced and self-excited oscillations in a natural gas fired lean premixed combustor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Daesik; Park, Sung Wook

    2010-11-15

    An experimental study of the flame response in a premixed gas turbine combustor has been conducted at room temperature and under atmospheric pressure inlet conditions using natural gas. The fuel is premixed with the air upstream of a choked inlet to avoid equivalence ratio fluctuations. Therefore the observed flame response is only the result of the imposed velocity fluctuations, which are produced using a variable-speed siren. Also, a variable length combustor is designed for investigating characteristics of self-excited instabilities. Measurements are made of the velocity fluctuation in the mixing section using hot wire anemometry and of the heat release fluctuation in the combustor using chemiluminescence emission. The results are analyzed to determine the phase and gain of the flame transfer function. The results show that the gain of flame transfer function is closely associated both with inlet flow forcing conditions such as frequency and amplitude of modulation as well as the operating conditions such as equivalence ratio. In order to predict the operating conditions where the combustor goes stable or unstable at given combustor and nozzle designs, time-lag analysis was tried using convection time delay measured from the phase information of the transfer function. The model prediction was in very good agreement with the self-excited instability measurement. However, spatial heat release distribution became more significant in long flames than in short flames and also had an important influence on the system damping procedure. (author)

  4. Phase transition in the hadron gas model

    International Nuclear Information System (INIS)

    Gorenstein, M.I.; Petrov, V.K.; Zinov'ev, G.M.

    1981-01-01

    A class of statistical models of hadron gas allowing an analytical solution is considered. A mechanism of a possible phase transition in such a system is found and conditions for its occurence are determined [ru

  5. Investigation of Sterilization Mechanism for Geobacillus stearothermophilus Spores with Plasma-Excited Neutral Gas

    Science.gov (United States)

    Matsui, Kei; Ikenaga, Noriaki; Sakudo, Noriyuki

    2015-09-01

    We investigate the mechanism of the sterilization with plasma-excited neutral gas that uniformly sterilizes both the space and inner wall of the reactor chamber at atmospheric pressure. Only reactive neutral species such as plasma-excited gas molecules and radicals are separated from the plasma and sent to the reactor chamber for chemical sterilization. The plasma source gas uses humidified mixture of nitrogen and oxygen. Geobacillus stearothermophilus spores and tyrosine which is amino acid are treated by the plasma-excited neutral gas. Shape change of the treated spore is observed by SEM, and chemical modification of the treated tyrosine is analyzed by HPLC. As a result, the surface of the treated spore shows depression. Hydroxylation and nitration of tyrosine are shown after the treatment. For these reasons, we believe that the sterilization with plasma-excited neutral gas results from the deformation of spore structure due to the chemical modification of amino acid.

  6. Studies of matrix diffusion in gas phase

    International Nuclear Information System (INIS)

    Hartikainen, K.; Timonen, J.; Vaeaetaeinen, K.; Pietarila, H.

    1994-03-01

    The diffusion of solutes from fractures into rock matrix is an important factor in the safety analysis of disposal of radioactive waste. Laboratory measurements are needed to complement field investigations for a reliable determination of the necessary transport parameters. Measurements of diffusion coefficients in tight rock samples are usually time consuming because the diffusion processes are slow. On the other hand it is well known that diffusion coefficients in the gas phase are roughly four orders of magnitude larger than those in the liquid phase. Therefore, for samples whose structures do not change much upon drying, it is possible to estimate the diffusion properties of the liquid phase when the properties of the gas phase are known. Advantages of the gas method are quick and easy measurements. In the measurements nitrogen was used as the carrier gas and helium as the tracer gas, and standard techniques have been used for helium detection. Techniques have been developed for both channel flow and through-diffusion measurements. The breakthrough curves have been measured in every experiment and all measurements have been modelled by using appropriate analytical models. As a result matrix porosities and effective diffusion coefficients in the gas phase have been determined. (12 refs., 21 figs., 6 tabs.)

  7. The electron spectrum of UF6 recorded in the gas phase

    Science.gov (United States)

    Mârtensson, N.; Malmquist, P.-Å.; Svensson, S.; Johansson, B.

    1984-06-01

    Gas phase core and valence electron spectra from UF6, excited by AlKα monochromatized x rays, in the binding energy range 0-1000 eV are presented. It is shown that the AlKα excited valence electron spectrum can be used to reassign the highest occupied molecular orbital (HOMO) in UF6. Many-body effects on the core levels are discussed and core level lifetimes are determined. The shift between solid phase and gas phase electron binding energies for core lines is used to discuss the U5 f population in UF6.

  8. Linking photochemistry in the gas and solution phase: S-H bond fission in p-methylthiophenol following UV photoexcitation.

    Science.gov (United States)

    Oliver, Thomas A A; Zhang, Yuyuan; Ashfold, Michael N R; Bradforth, Stephen E

    2011-01-01

    Gas-phase H (Rydberg) atom photofragment translational spectroscopy and solution-phase femtosecond-pump dispersed-probe transient absorption techniques are applied to explore the excited state dynamics of p-methylthiophenol connecting the short time reactive dynamics in the two phases. The molecule is excited at a range of UV wavelengths from 286 to 193 nm. The experiments clearly demonstrate that photoexcitation results in S-H bond fission--both in the gas phase and in ethanol solution-and that the resulting p-methythiophenoxyl radical fragments are formed with significant vibrational excitation. In the gas phase, the recoil anisotropy of the H atom and the vibrational energy disposal in the p-MePhS radical products formed at the longer excitation wavelengths reveal the operation of two excited state dissociation mechanisms. The prompt excited state dissociation motif appears to map into the condensed phase also. In both phases, radicals are produced in both their ground and first excited electronic states; characteristic signatures for both sets of radical products are already apparent in the condensed phase studies after 50 fs. No evidence is seen for either solute ionisation or proton coupled electron transfer--two alternate mechanisms that have been proposed for similar heteroaromatics in solution. Therefore, at least for prompt S-H bond fissions, the direct observation of the dissociation process in solution confirms that the gas phase photofragmentation studies indeed provide important insights into the early time dynamics that transfer to the condensed phase.

  9. The nuclear liquid gas phase transition and phase coexistence

    International Nuclear Information System (INIS)

    Chomaz, Ph.

    2001-01-01

    In this talk we will review the different signals of liquid gas phase transition in nuclei. From the theoretical side we will first discuss the foundations of the concept of equilibrium, phase transition and critical behaviors in infinite and finite systems. From the experimental point of view we will first recall the evidences for some strong modification of the behavior of hot nuclei. Then we will review quantitative detailed analysis aiming to evidence phase transition, to define its order and phase diagram. Finally, we will present a critical discussion of the present status of phase transitions in nuclei and we will draw some lines for future development of this field. (author)

  10. The nuclear liquid gas phase transition and phase coexistence

    Energy Technology Data Exchange (ETDEWEB)

    Chomaz, Ph

    2001-07-01

    In this talk we will review the different signals of liquid gas phase transition in nuclei. From the theoretical side we will first discuss the foundations of the concept of equilibrium, phase transition and critical behaviors in infinite and finite systems. From the experimental point of view we will first recall the evidences for some strong modification of the behavior of hot nuclei. Then we will review quantitative detailed analysis aiming to evidence phase transition, to define its order and phase diagram. Finally, we will present a critical discussion of the present status of phase transitions in nuclei and we will draw some lines for future development of this field. (author)

  11. Magnetic excitations in ferromagnetic phase of MnP

    International Nuclear Information System (INIS)

    Yano, Shin-ichiro; Itoh, Shinichi; Yokoo, Tetsuya; Satoh, Setsuo; Kawana, Daichi; Kousaka, Yusuke; Akimitsu, Jun; Endoh, Yasuo

    2013-01-01

    Inelastic neutron scattering experiments were performed on an intermetallic compound, MnP. We used a newly developed High Resolution Chopper Spectrometer, HRC, for energy transfers E≤75meV, besides various triple axis spectrometers; LTAS for energy transfers E≤2meV, TOPAN for E≤7.5meV and TAS-1 for E≤35meV. Spin wave excitations were observed in the ferromagnetic phase of MnP in the entire Brillouin zone along the a ⁎ - and b ⁎ -axes. The zone boundary energies of spin waves were determined to be around 60 meV along the a ⁎ -axis and around 75 meV along the b ⁎ -axis, and the dispersion relations showed two branches for both axes. The observed dispersion relations of spin waves were well described by an isotropic Heisenberg interaction adding a single ion anisotropy with two sub-lattices. - Highlights: • Inelastic neutron scattering experiments were performed mainly using pulsed neutrons. • Spin waves were observed in the ferromagnetic phase of an intermetallic compound MnP. • The dispersion relations were determined entirely along the a ⁎ - and b ⁎ -axes. • We could describe the observed dispersion relations by a two sub-lattice model

  12. Experimental station for gas phase fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Stankiewicz, M.; Garcia, E. Melero; Ruiz, J. Alvarez; Erman, P.; Hatherly, P.A.; Kivimaeki, A.; Rachlew, E.; Rius i Riu, J.

    2004-01-01

    The details of an experimental setup for gas phase atomic and molecular fluorescence measurements using synchrotron radiation are described in this article. The most significant part of the apparatus is an optical arrangement, which allows for simultaneous measurements of dispersed as well as total fluorescence intensity using an effusive gas jet and an inbuilt gas cell assembled in a convenient plug and measure configuration. The first measurements concerning fluorescence of the N 2 molecule around the N 1s edge obtained with this setup are presented

  13. Gas flow headspace liquid phase microextraction.

    Science.gov (United States)

    Yang, Cui; Qiu, Jinxue; Ren, Chunyan; Piao, Xiangfan; Li, Xifeng; Wu, Xue; Li, Donghao

    2009-11-06

    There is a trend towards the use of enrichment techniques such as microextraction in the analysis of trace chemicals. Based on the theory of ideal gases, theory of gas chromatography and the original headspace liquid phase microextraction (HS-LPME) technique, a simple gas flow headspace liquid phase microextraction (GF-HS-LPME) technique has been developed, where the extracting gas phase volume is increased using a gas flow. The system is an open system, where an inert gas containing the target compounds flows continuously through a special gas outlet channel (D=1.8mm), and the target compounds are trapped on a solvent microdrop (2.4 microL) hanging on the microsyringe tip, as a result, a high enrichment factor is obtained. The parameters affecting the enrichment factor, such as the gas flow rate, the position of the microdrop, the diameter of the gas outlet channel, the temperatures of the extracting solvent and of the sample, and the extraction time, were systematically optimized for four types of polycyclic aromatic hydrocarbons. The results were compared with results obtained from HS-LPME. Under the optimized conditions (where the extraction time and the volume of the extracting sample vial were fixed at 20min and 10mL, respectively), detection limits (S/N=3) were approximately a factor of 4 lower than those for the original HS-LPME technique. The method was validated by comparison of the GF-HS-LPME and HS-LPME techniques using data for PAHs from environmental sediment samples.

  14. High power electron beam accelerators for gas laser excitation

    International Nuclear Information System (INIS)

    Kelly, J.G.; Martin, T.H.; Halbleib, J.A.

    1976-06-01

    A preliminary parameter investigation has been used to determine a possible design of a high-power, relativistic electron beam, transversely excited laser. Based on considerations of present and developing pulsed power technology, broad area diode physics and projected laser requirements, an exciter is proposed consisting of a Marx generator, pulse shaping transmission lines, radially converging ring diodes and a laser chamber. The accelerator should be able to deliver approximately 20 kJ of electron energy at 1 MeV to the 10 4 cm 2 cylindrical surface of a laser chamber 1 m long and 0.3 m in diameter in 24 ns with very small azimuthal asymmetry and uniform radial deposition

  15. Coherent captivity of population in gas of excited atoms

    International Nuclear Information System (INIS)

    Anisimov, P.M.; Akhmedzhanov, R.A.; Zelenskij, I.V.; Kolesov, R.L.; Kuznetsova, E.A.

    2003-01-01

    The coherent captivity of the population in the gaseous discharge on the transitions between the neon atoms excited levels is studied. The resonances, corresponding to the origination of the population coherent captivity in the Λ- and V-schemes on the Zeeman sublevels of the low and upper working states, were observed in the presence of the longitudinal magnetic field. The effect of the nonlinear rotation of the polarization plane under the conditions of the population coherent captivity was studied. The possibility of applying the results of the work for the diagnostics of the local magnetic fields and other plasma parameters in the gaseous discharges is considered [ru

  16. Optical processes in the performance and recovery of gas-phase switches

    International Nuclear Information System (INIS)

    Gundersen, M.

    1982-01-01

    In this paper several optical processes that may be used to affect gas-phase switch performance and operation are discussed, and approaches using a laser to increase recovery rates of switches are presented. In the latter the laser is used during the recovery phase rather than the conductive or closure phase. This papper suggests that it should be possible to use a low-power laser (e.g., one that is technologically feasible to use as part of a switch) to assist in opening the switch by quenching excited atomic and/or molecular species. The application of laser-induced energy extraction to gas-phase switches is also discussed

  17. Absolute carrier phase effects in the two-color excitation of dipolar molecules

    International Nuclear Information System (INIS)

    Brown, Alex; Meath, W.J.; Kondo, A.E.

    2002-01-01

    The pump-probe excitation of a two-level dipolar (d≠0) molecule, where the pump frequency is tuned to the energy level separation while the probe frequency is extremely small, is examined theoretically as an example of absolute phase control of excitation processes. The state populations depend on the probe field's absolute carrier phase but are independent of the pump field's absolute carrier phase. Interestingly, the absolute phase effects occur for pulse durations much longer and field intensities much weaker than those required to see such effects in single pulse excitation

  18. Thermosonic Testing with Phased Matched Guided Wave Excitation

    OpenAIRE

    Markus RAHAMMER, Igor SOLODOV, Wolfgang BISLE, Dieter SCHERLING , Marc KREUTZBRUCK

    2016-01-01

    Abstract. Vibrothermography, is an established NDT method praised for its full-field and defect-selective imaging. Especially for cracks and similar damage, defect signals are produced within seconds for a wide variety of materials. Usually high power sonotrodes that are applied with kN pressure are employed in order to maximize ultrasonic excitation of the specimens. An increase in excitation power is used for boosting the defect signal strength, i.e. the rise in temperature. Improvements...

  19. Nucleation and dissociation of nano-particles in gas phase

    International Nuclear Information System (INIS)

    Feiden, P.

    2007-09-01

    This work deals with the study of nano-particles formation in gas phase and their dissociation pathways after an optical excitation. The clusters formation decomposes in two steps: a seed is formed (nucleation phase) and sticks atoms during its propagation in a sodium atomic vapor (growth phase). Those two steps have been observed separately for homogeneous Na n and heterogeneous Na n X particles (X = (NaOH) 2 or (Na 2 O) 2 ). The growth mechanism is well interpreted by a Monte Carlo simulation taking into account an accretion mechanism with hard-sphere cross section. The homogeneous nucleation mechanism has been highlighted by a direct comparison with the Classical Nucleation Theory predictions. The clusters fragmentation of ionic Na + (NaOH) p et Na + (NaF) p particles is studied in the second part. The way clusters fragment with size when they are excited optically is compared with theoretical previsions: this highlights the existence of an energetic barrier for special size of clusters. Finally, the fragmentation of doubly charged Na + Na + (NaOH) p clusters shows a competition between the fission into two single charged fragments and the unimolecular evaporation of a neutral fragment. (author)

  20. Gas-Phase Reactivity of Microsolvated Anions

    DEFF Research Database (Denmark)

    Thomsen, Ditte Linde

    the gas-phase α-effect. The experimental studies are performed by means of the flowing after glow selected ion flow tube technique, and these are supplemented by electronic structure calculations. The α-nucleophile employed is the microsolvated hydrogen peroxide anion whose reactivity is compared......Gas-phase studies of ion-molecule reactions shed light on the intrinsic factors that govern reactivity; and even solvent effects can be examined in the gasphase environment by employing microsolvated ions. An area that has received considerable attention with regard to the interplay between...... to that of a series of microsolvated oxygen centered anions. The association of the nucleophiles with a single water or methanol molecule allows the α-effect to be observed in the SN2 reaction with methyl chloride; this effect was not apparent in the reactions of the unsolvated anions. The results suggest...

  1. Deviations from the Boltzmann distribution in vibrationally excited gas flows

    International Nuclear Information System (INIS)

    Offenhaeuser, F.; Frohn, A.

    1986-01-01

    A new model for the exchange of vibrational energy in one-dimensional flows of CO 2 -H 2 O-N 2 -O 2 -He gas mixtures is presented. In contrast to previous models, the assumption of local Boltzmann distributions for the vibrational degrees of freedom is not required. This generalization was achieved by the assumption that the molecules are harmonic oscillators with one or more degrees of freedom represented by finite numbers of energy levels. The population densities of these energy levels are coupled by a set of rate equations. It is shown that in some cases of molecular gas flow the Boltzmann distribution for the vibrational degrees of freedom may be disturbed. 12 references

  2. Ionic liquid stationary phases for gas chromatography.

    Science.gov (United States)

    Poole, Colin F; Poole, Salwa K

    2011-04-01

    This article provides a summary of the development of ionic liquids as stationary phases for gas chromatography beginning with early work on packed columns that established details of the retention mechanism and established working methods to characterize selectivity differences compared with molecular stationary phases through the modern development of multi-centered cation and cross-linked ionic liquids for high-temperature applications in capillary gas chromatography. Since there are many reviews on ionic liquids dealing with all aspects of their chemical and physical properties, the emphasis in this article is placed on the role of gas chromatography played in the design of ionic liquids of low melting point, high thermal stability, high viscosity, and variable selectivity for separations. Ionic liquids provide unprecedented opportunities for extending the selectivity range and temperature-operating range of columns for gas chromatography, an area of separation science that has otherwise been almost stagnant for over a decade. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Influence of excited molecules on electron swarm transport coefficients and gas discharge kinetics

    International Nuclear Information System (INIS)

    Petrovic, Z.L.; Jovanovic, J.V.; Raspopovic, Z.M.; Bzenic, S.A.; Vrhovac, S.B.

    1997-01-01

    In this paper we study different effects of excited molecules on swarm parameters, electron energy distribution functions and gas discharge modeling. First we discuss a possible experiment in parahydrogen to resolve the discrepancy in hydrogen vibrational excitation cross section data. Negative differential conductivity (NDC) is a kinetic phenomenon which manifests itself in a particular dependence of the drift velocity on E=N and it is affected by superelastic collisions with excited states. A complete kinetic scheme for argon required to model excited state densities in gas discharges is also described. These results are used to explain experiments in capacitively and inductively coupled RF plasmas used for processing. The paper illustrates the application of atomic and molecular collision data, swarm data and the theoretical techniques in modeling of gas discharges with large abundances of excited molecules. It is pointed out that swarm experiments with excited molecules are lacking and that there is a shortage of reliable data, while the numerical procedures are sufficiently developed to include all the important effects. (authors). 59 refs., 12 figs

  4. Multi-quantum excitation in optically pumped alkali atom: rare gas mixtures

    Science.gov (United States)

    Galbally-Kinney, K. L.; Rawlins, W. T.; Davis, S. J.

    2014-03-01

    Diode-pumped alkali laser (DPAL) technology offers a means of achieving high-energy gas laser output through optical pumping of the D-lines of Cs, Rb, and K. The exciplex effect, based on weak attractive forces between alkali atoms and polarizable rare gas atoms (Ar, Kr, Xe), provides an alternative approach via broadband excitation of exciplex precursors (XPAL). In XPAL configurations, we have observed multi-quantum excitation within the alkali manifolds which result in infrared emission lines between 1 and 4 μm. The observed excited states include the 42FJ states of both Cs and Rb, which are well above the two-photon energy of the excitation laser in each case. We have observed fluorescence from multi-quantum states for excitation wavelengths throughout the exciplex absorption bands of Cs-Ar, Cs-Kr, and Cs-Xe. The intensity scaling is roughly first-order or less in both pump power and alkali concentration, suggesting a collisional energy pooling excitation mechanism. Collisional up-pumping appears to present a parasitic loss term for optically pumped atomic systems at high intensities, however there may also be excitation of other lasing transitions at infrared wavelengths.

  5. Photoresponse of the protonated Schiff-base retinal chromophore in the gas phase

    DEFF Research Database (Denmark)

    Toker, Jonathan; Rahbek, Dennis Bo; Kiefer, H V

    2013-01-01

    The fragmentation, initiated by photoexcitation as well as collisionally-induced excitation, of several retinal chromophores was studied in the gas phase. The chromophore in the protonated Schiff-base form (RPSB), essential for mammalian vision, shows a remarkably selective photoresponse. The sel......The fragmentation, initiated by photoexcitation as well as collisionally-induced excitation, of several retinal chromophores was studied in the gas phase. The chromophore in the protonated Schiff-base form (RPSB), essential for mammalian vision, shows a remarkably selective photoresponse...... modifications of the chromophore. We propose that isomerizations play an important role in the photoresponse of gas-phase retinal chromophores and guide internal conversion through conical intersections. The role of protein interactions is then to control the specificity of the photoisomerization in the primary...

  6. Phase compensated gas turbine governor for damping oscillatory modes

    Energy Technology Data Exchange (ETDEWEB)

    Yee, S.K. [Siemens Transmission and Distribution Limited, Manchester (United Kingdom); Milanovic, J.V. [School of Electrical and Electronic Engineering, University of Manchester, PO Box 88, Manchester M60 1 QD (United Kingdom); Hughes, F.M. [Manchester (United Kingdom)

    2009-08-15

    With market deregulation, there is constant pressure to utilise existing assets in more effective ways in order to achieve high levels of performance and as governor technologies mature the ability of governors to achieve much more than the standard power-frequency regulation function increases. Thus, this paper has focused on a more active use of governor control for a gas turbine to provide improved system stabilisation and performance via the inclusion of phase compensation in the governor control loop. Due to the decoupled nature of the mechanical power and excitation control loops, performance improvement via governor control does not interfere with generator voltage regulation, which is a drawback of conventional generator damping provision via a power system stabiliser (PSS). In addition, the mechanical power control loop is also less affected by the operating condition of the power system and is hence more robust. It is shown that inclusion of appropriate phase compensation in the governor control loop can improve dynamic and transient stability, either alone or in conjunction with a PSS in the exciter control loop, without adversely interfering with voltage control or changing steady state power-frequency regulation. (author)

  7. Three phase carbon EOS model with electronic excitation

    International Nuclear Information System (INIS)

    van Thiel, M.; Ree, F.H.; Grover, R.

    1987-07-01

    A simple and rapid way for computing EOS data of multiphase solids with a liquid phase is described with emphasis on carbon. The method uses a scaling model for the liquid phase and includes a provision for electronic effects. The free energy minimum determines the stable phase

  8. Excited-state lifetime measurements: Linearization of the Foerster equation by the phase-plane method

    International Nuclear Information System (INIS)

    Love, J.C.; Demas, J.N.

    1983-01-01

    The Foerster equation describes excited-state decay curves involving resonance intermolecular energy transfer. A linearized solution based on the phase-plane method has been developed. The new method is quick, insensitive to the fitting region, accurate, and precise

  9. Infrared spectroscopy of gas-phase clusters using a free-electron laser

    International Nuclear Information System (INIS)

    Heijnsbergen, D. van; Helden, G. von; Meijer, G.

    2002-01-01

    Most clusters produced in the gas phase, especially those containing metals, remain largely uncharaterized, among these are transition metal - carbide, -oxide and -nitride clusters. A method for recording IR spectra of strongly bound gas-phase clusters is presented. It is based on a free-electron laser called Felix, characterized by wide wavelength tuning range, covering almost the full 'molecular finger print' region, high power and fluence which make it suited to excite gas-phase species i.e. gas -phase clusters. Neutral clusters were generated by laser vaporization technique, ions that were created after the interaction with the free-electron laser were analyzed in a flight mass spectrometer. Experiments were run with titanium carbide clusters and their IR spectra given. It was shown that this method is suited to strongly bound clusters with low ionization energies, a condition met for many pure metal clusters and metal compound clusters. (nevyjel)

  10. Gas phase reactive collisions, experimental approach

    Directory of Open Access Journals (Sweden)

    Canosa A.

    2012-01-01

    Full Text Available Since 1937 when the first molecule in space has been identified, more than 150 molecules have been detected. Understanding the fate of these molecules requires having a perfect view of their photochemistry and reactivity with other partners. It is then crucial to identify the main processes that will produce and destroy them. In this chapter, a general view of experimental techniques able to deliver gas phase chemical kinetics data at low and very low temperatures will be presented. These techniques apply to the study of reactions between neutral reactants on the one hand and reactions involving charge species on the other hand.

  11. Gas-Phase Excited State Dynamics of Bithiophenes

    DEFF Research Database (Denmark)

    Skov, Anders Bo; Baldtzer Liisberg, Mikkel; Bjørnholst, Martin Alex

    Ved hjælp af pump-probe spektroskopi undersøges de exciterede tilstandes dynamik af forskellige modelsystemer af polythiophen-polymerer til brug i solceller. Resultaterne viser at langt-levede, nyttige tilstande opstår allerede ved bithiophen-niveau, mens at thiophen og dimethylthiophen er dårlige...

  12. Excitable dynamics in high-Lewis number premixed gas combustion at normal and microgravity

    Science.gov (United States)

    Pearlman, Howard

    1995-01-01

    g and 1g, buoyant flicker is not the mechanism which drives the pulsations. Moreover, all of the instabilities at 1g and mu g have characteristic frequencies on the O(100Hz). This value is lower than the fundamental, longitudinal acoustic frequencies of the tubes which suggests that the instabilities are not acoustically driven. The patterns formed by this reaction bear remarkable similarities with the patterns formed in most excitable media when the behavior of the system is driven by couplings between chemical reaction and diffusion (e.g., Belousov-Zhabotinsky reaction, Patterns in slime molds, spiral waves in the retina of a bird's eye). While it is recognized that the chemical mechanism associated with this premixed gas reaction is exponentially sensitive to temperature and undoubtedly different from those which govern previously observed excitable media (most are isothermal, or weakly exothermic, liquid phase reactions), similar spatial and temporal patterns should not come as a complete surprise considering heat and mass diffusion are self similar. It is concluded that this premixed gas system is a definitive example of a diffusive-thermal, gas-phase oscillator based on these experimental results and their favorable comparison with theory.

  13. Gas phase absorption studies of photoactive yellow protein chromophore derivatives.

    Science.gov (United States)

    Rocha-Rinza, Toms; Christiansen, Ove; Rajput, Jyoti; Gopalan, Aravind; Rahbek, Dennis B; Andersen, Lars H; Bochenkova, Anastasia V; Granovsky, Alexander A; Bravaya, Ksenia B; Nemukhin, Alexander V; Christiansen, Kasper Lincke; Nielsen, Mogens Brøndsted

    2009-08-27

    Photoabsorption spectra of deprotonated trans p-coumaric acid and two of its methyl substituted derivatives have been studied in gas phase both experimentally and theoretically. We have focused on the spectroscopic effect of the location of the two possible deprotonation sites on the trans p-coumaric acid which originate to either a phenoxide or a carboxylate. Surprisingly, the three chromophores were found to have the same absorption maximum at 430 nm, in spite of having different deprotonation positions. However, the absorption of the chromophore in polar solution is substantially different for the distinct deprotonation locations. We also report on the time scales and pathways of relaxation after photoexcitation for the three photoactive yellow protein chromophore derivatives. As a result of these experiments, we could detect the phenoxide isomer within the deprotonated trans p-coumaric acid in gas phase; however, the occurrence of the carboxylate is uncertain. Several computational methods were used simultaneously to provide insights and assistance in the interpretation of our experimental results. The calculated excitation energies S(0)-S(1) are in good agreement with experiment for those systems having a negative charge on a phenoxide moiety. Although our augmented multiconfigurational quasidegenerate perturbation theory calculations agree with experiment in the description of the absorption spectrum of anions with a carboxylate functional group, there are some puzzling disagreements between experiment and some calculational methods in the description of these systems.

  14. Phase transitions and topological excitations in hypergauge theories

    International Nuclear Information System (INIS)

    Nencka-Ficek, H.

    1985-01-01

    The problems connected with the phase structure of antisymmetric tensor gauge fields are investigated. (s+1)-dimensional hyperloops cannot be constructed in (s+1)-dimensional lattices. This is the cause of a lack of phase transitions in the U(1) theories with fields being sth-kind gauge invariant in the (s+1)-dimensional lattice

  15. Phase transitions in a vortex gas

    International Nuclear Information System (INIS)

    Shah, P.A.

    1995-01-01

    It has been shown recently that the motion of solitons at couplings around a critical coupling can be reduced to the dynamics of particles (the zeros of the Higgs field) on a curved manifold with potential. The curvature gives a velocity-dependent force, and the magnitude of the potential is proportional to the distance from a critical coupling. In this paper we apply this approximation to determining the equation of state of a gas of vortices in the abelian Higgs model. We derive a virial expansion using certain known integrals of the metric, and the second virial coefficient is calculated, determining the behaviour of the gas at low densities. A formula for determining higher-order coefficients is given. At low densities and temperatures T >>λ the equation of state is of the Van der Waals form (P+b N 2 /A 2 )(A-aN) = NT with a=4π and b=-4.89πλ where λ is a measure of the distance from critical coupling. It is found that there is no phase transition in a low-density type-II gas, but there is a transition in the type-I case between a condensed and gaseous state. We conclude with a discussion of the relation of our results to vortex behaviour in superconductors. ((orig.))

  16. Influence of gas discharge parameters on emissions from a dielectric barrier discharge excited argon excimer lamp

    Directory of Open Access Journals (Sweden)

    Mike Collier

    2011-11-01

    Full Text Available A dielectric barrier discharge excited neutral argon (Ar I excimer lamp has been developed and characterised. The aim of this study was to develop an excimer lamp operating at atmospheric pressure that can replace mercury lamps and vacuum equipment used in the sterilisation of medical equipment and in the food industry. The effects of discharge gas pressure, flow rate, excitation frequency and pulse width on the intensity of the Ar I vacuum ultraviolet (VUV emission at 126 nm and near infrared (NIR lines at 750.4 nm and 811.5 nm have been investigated. These three lines were chosen as they represent emissions resulting from de-excitation of excimer states that emit energetic photons with an energy of 9.8 eV. We observed that the intensity of the VUV Ar2* excimer emission at 126 nm increased with increasing gas pressure, but decreased with increasing excitation pulse frequency and pulse width. In contrast, the intensities of the NIR lines decreased with increasing gas pressure and increased with increasing pulse frequency and pulse width. We have demonstrated that energetic VUV photons of 9.8 eV can be efficiently generated in a dielectric barrier discharge in Ar.

  17. A study on rare gas - oxygen reactions excited by low temperature plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Hiroaki; Kiuchi, Kiyoshi; Saburi, Tei; Fukaya, Kiyoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    The concentration of radioactive rare gases like Xe and Kr in nuclear fuels on PWRs and BWRs increases promptly with dependent on the burn-up ratio. These gases are affect to the long performance of nuclear fuel elements due to accumulate in gap between cladding and fuel, because it has the low thermal conductivity. It is also required to develop the practical means to correct these gases including in the off-gas in nuclear plants for inhibiting the environmental pollution. On the present study, we carried out the fundamental research to evaluate the chemical reactivity of these gases under heavy irradiation. We proposed the new excitation mechanism of these gases by expecting the formation of low energy plasma under irradiation. The chemical reactivity on rare gas-oxygen system was examined by using the low energy plasma driven reaction apparatus installed the RF excitation source. The density of electrons and lower pressure limit for the RF excitation was depended on the ionization energy of each gas. It is clarified that Xe is easy to form gaseous oxide due to the high excitation efficiency in low energy plasma. (author)

  18. Photoemission from excited states in rare gas solids by combining synchrotronradiation with a laser

    International Nuclear Information System (INIS)

    Bernstorff, S.

    1984-09-01

    A new spectroscopic method has been developed to study excited states in rare gas solids: Excitons and conductionband-states are populated by synchrotron radiation (photon energy hw SR =5 - 30 eV). Subsequently electrons from these bound or conduction band-states are excited above the vacuum level of the solid by a pulsed dye laser (hw L =1.9 - 3.7 eV). This experimental technique was applied to solid Xe, Kr, Ar and Ne. (orig./GSCH)

  19. Phase transitions in solid Kr-CH4 solutions and rotational excitations in phase II

    International Nuclear Information System (INIS)

    Bagatskii, M.I.; Mashchenko, D.A.; Dudkin, V.V.

    2007-01-01

    The heat capacity C p of solid Kr-n CH 4 solutions with the CH 4 concentrations n=0.82, 0.86, 0.90 as well as solutions with n=0.90, 0.95 doped with 0.002 O 2 impurity has been investigated under equilibrium vapor pressure over the internal 1-24 K. The (T,n)-phase diagram was refined and the region of two-phase states was determined for Kr-n CH 4 solid solutions. The contribution of the rotational subsystem, C r ot, to the heat capacity of the solutions has been separated. Analysis of C r ot(T) at T 1 and E 2 between the tunnel levels of the A-, T- and A-, E--nuclear-spin species of CH 4 molecules in the orientationally ordered subsystem, and to determine the effective energy gaps E 1 between lowest levels of the A- and T- species. The relations τ(n) and E 1 (n) stem from changes of the effective potential field caused as the replacement of CH 4 molecules by Kr atoms at sites of the ordered sublattices. The effective gaps E L between a group of tunnel levels of the ground-state liberation state and the nearest group of excited levels of the liberation state of the ordered CH 4 molecules in the solutions with n=0.90 (E L =52 K) and 0.95 (E L =55 K) has been estimated

  20. Femtosecond time-resolved studies of coherent vibrational Raman scattering in large gas-phase molecules

    International Nuclear Information System (INIS)

    Hayden, C.C.; Chandler, D.W.

    1995-01-01

    Results are presented from femtosecond time-resolved coherent Raman experiments in which we excite and monitor vibrational coherence in gas-phase samples of benzene and 1,3,5-hexatriene. Different physical mechanisms for coherence decay are seen in these two molecules. In benzene, where the Raman polarizability is largely isotropic, the Q branch of the vibrational Raman spectrum is the primary feature excited. Molecules in different rotational states have different Q-branch transition frequencies due to vibration--rotation interaction. Thus, the macroscopic polarization that is observed in these experiments decays because it has many frequency components from molecules in different rotational states, and these frequency components go out of phase with each other. In 1,3,5-hexatriene, the Raman excitation produces molecules in a coherent superposition of rotational states, through (O, P, R, and S branch) transitions that are strong due to the large anisotropy of the Raman polarizability. The coherent superposition of rotational states corresponds to initially spatially oriented, vibrationally excited, molecules that are freely rotating. The rotation of molecules away from the initial orientation is primarily responsible for the coherence decay in this case. These experiments produce large (∼10% efficiency) Raman shifted signals with modest excitation pulse energies (10 μJ) demonstrating the feasibility of this approach for a variety of gas phase studies. copyright 1995 American Institute of Physics

  1. Plasma excitation processes in flue gas simulated with Monte Carlo electron dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Tas, M.A.; Veldhuizen, E.M. van; Rutgers, W.R. [Eindhoven University of Technology (Netherlands). Div. of Electrical Energy Systems

    1997-06-07

    The excitation of gas molecules in flue gas by electron impact is calculated with a Monte Carlo (MC) algorithm for electron dynamics in partially ionized gases. The MC algorithm is straightforward for any mixture of molecules for which cross sections are available. Electron drift is simulated in the first case for homogeneous electric fields and in the second case for secondary electrons which are produced by electron-beam irradiation. The electron energy distribution function {epsilon}-bar{sub {theta}}, V-bar{sub d}, {lambda}-bar, the energy branching and the rate of excitation are calculated for standard gas mixtures of Ar-N{sub 2}, O{sub 2} and H{sub 2}O. These fundamental process parameters are needed for the study of reactions to remove NO{sub x} from flue gas. The calculated results indicate that the production of highly excited molecules in the high electric field of a streamer corona discharge has an efficiency similar to that of electron-beam irradiation. (author)

  2. Microfluidic and nanofluidic phase behaviour characterization for industrial CO2, oil and gas.

    Science.gov (United States)

    Bao, Bo; Riordon, Jason; Mostowfi, Farshid; Sinton, David

    2017-08-08

    Microfluidic systems that leverage unique micro-scale phenomena have been developed to provide rapid, accurate and robust analysis, predominantly for biomedical applications. These attributes, in addition to the ability to access high temperatures and pressures, have motivated recent expanded applications in phase measurements relevant to industrial CO 2 , oil and gas applications. We here present a comprehensive review of this exciting new field, separating microfluidic and nanofluidic approaches. Microfluidics is practical, and provides similar phase properties analysis to established bulk methods with advantages in speed, control and sample size. Nanofluidic phase behaviour can deviate from bulk measurements, which is of particular relevance to emerging unconventional oil and gas production from nanoporous shale. In short, microfluidics offers a practical, compelling replacement of current bulk phase measurement systems, whereas nanofluidics is not practical, but uniquely provides insight into phase change phenomena at nanoscales. Challenges, trends and opportunities for phase measurements at both scales are highlighted.

  3. Resonance Polarization and Phase-Mismatched CARS of Pheophytin b Excited in the Qy Band

    NARCIS (Netherlands)

    de Boeij, W.P.; Lucassen, G.W.; Lucassen, Gerald; Otto, Cornelis; Greve, Jan

    1993-01-01

    Resonance polarization and phase-mismatched coherent anti-Stokes Raman scattering (CARS) measurements were performed on pheophytin b dissolved in acetone excited in the Qy absorption band, where strong broad fluorescence makes spontaneous Raman spectroscopy impossible. The phase-mismatching

  4. Modeling and Performance of a Self-Excited Two-Phase Reluctance ...

    African Journals Online (AJOL)

    A self-excited two-phase reluctance generator (SETPRG) with balanced stator winding is presented. A unique balanced two-phase stator winding was designed with emphasis on obtaining a stator MMF waveform with minimum space harmonics. Then a mathematical model by which the dynamic behavior of the generator ...

  5. Laser spectroscopy of a halocarbocation in the gas phase: CH2I+.

    Science.gov (United States)

    Tao, Chong; Mukarakate, Calvin; Reid, Scott A

    2006-07-26

    We report the first gas-phase observation of the electronic spectrum of a simple halocarbocation, CH2I+. The ion was generated rotationally cold (Trot approximately 20 K) using pulsed discharge methods and was detected via laser spectroscopy. The identity of the spectral carrier was confirmed by modeling the rotational contour observed in the excitation spectra and by comparison of ground state vibrational frequencies determined by single vibronic level emission spectroscopy with Density Functional Theory (DFT) predictions. The transition was assigned as 3A1 gas phase should open new avenues for study of the structure and reactivity of these important ions.

  6. Phase transitions in a gas of anyons

    International Nuclear Information System (INIS)

    MacKenzie, R.; Nebia-Rahal, F.; Paranjape, M. B.; Richer, J.

    2010-01-01

    We continue our numerical Monte Carlo simulation of a gas of closed loops on a 3 dimensional lattice, however, now in the presence of a topological term added to the action which corresponds to the total linking number between the loops. We compute the linking number using a novel approach employing certain notions from knot theory. Adding the topological term converts the particles into anyons. Interpreting the model as an effective theory that describes the 2+1-dimensional Abelian Higgs model in the asymptotic strong-coupling regime, the topological linking number simply corresponds to the addition to the action of the Chern-Simons term. The system continues to exhibit a phase transition as a function of the vortex mass as it becomes small. We find the following new results. The Chern-Simons term has no effect on the Wilson loop. On the other hand, it does effect the 't Hooft loop of a given configuration, adding the linking number of the 't Hooft loop with all of the dynamical vortex loops. We find the unexpected result that both the Wilson loop and the 't Hooft loop exhibit a perimeter law even though there are no massless particles in the theory, in both phases of the theory. It should be noted that our method suffers from numerical instabilities if the coefficient of the Chern-Simons term is too large; thus, we have restricted our results to small values of this parameter. Furthermore, interpreting the lattice loop gas as an effective theory describing the Abelian Higgs model is only known to be true in the infinite coupling limit; for strong but finite coupling this correspondence is only a conjecture, the validity of which is beyond the scope of this article.

  7. Transferring pharmaceuticals into the gas phase

    Science.gov (United States)

    Christen, Wolfgang; Krause, Tim; Rademann, Klaus

    2008-11-01

    The dissolution of molecules of biological interest in supercritical carbon dioxide is investigated using pulsed molecular beam mass spectrometry. Due to the mild processing temperatures of most supercritical fluids, their adiabatic expansion into vacuum permits to transfer even thermally very sensitive substances into the gas phase, which is particularly attractive for pharmaceutical and biomedical applications. In addition, supercritical CO2constitutes a chemically inert solvent that is compatible with hydrocarbon-free ultrahigh vacuum conditions. Here, we report on the dissolution and pulsed supersonic jet expansion of caffeine (C8H10N4O2), the provitamin menadione (C11H8O2), and the amino acid derivative l-phenylalanine tert-butyl ester hydrochloride (C6H5CH2CH(NH2)COOC(CH3)3[dot operator]HCl), into vacuum. An on-axis residual gas analyzer is used to monitor the relative amounts of solute and solvent in the molecular beam as a function of solvent densityE The excellent selectivity and sensitivity provided by mass spectrometry permits to probe even trace amounts of solutes. The strong density variation of CO2 close to the critical point results in a pronounced pressure dependence of the relative ion currents of solute and solvent molecules, reflecting a substantial change in solubility.

  8. Fully phase-encoded MRI near metallic implants using ultrashort echo times and broadband excitation.

    Science.gov (United States)

    Wiens, Curtis N; Artz, Nathan S; Jang, Hyungseok; McMillan, Alan B; Koch, Kevin M; Reeder, Scott B

    2018-04-01

    To develop a fully phase-encoded MRI method for distortion-free imaging near metallic implants, in clinically feasible acquisition times. An accelerated 3D fully phase-encoded acquisition with broadband excitation and ultrashort echo times is presented, which uses a broadband radiofrequency pulse to excite the entire off-resonance induced by the metallic implant. Furthermore, fully phase-encoded imaging is used to prevent distortions caused by frequency encoding, and to obtain ultrashort echo times for rapidly decaying signal. Phantom and in vivo acquisitions were used to describe the relationship among excitation bandwidth, signal loss near metallic implants, and T 1 weighting. Shorter radiofrequency pulses captured signal closer to the implant by improving spectral coverage and allowing shorter echo times, whereas longer pulses improved T 1 weighting through larger maximum attainable flip angles. Comparisons of fully phase-encoded acquisition with broadband excitation and ultrashort echo times to T 1 -weighted multi-acquisition with variable resonance image combination selective were performed in phantoms and subjects with metallic knee and hip prostheses. These acquisitions had similar contrast and acquisition efficiency. Accelerated fully phase-encoded acquisitions with ultrashort echo times and broadband excitation can generate distortion free images near metallic implants in clinically feasible acquisition times. Magn Reson Med 79:2156-2163, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  9. Gas phase collision dynamics by means of pulse-radiolysis methods

    International Nuclear Information System (INIS)

    Hatano, Yoshihiko

    1989-01-01

    After a brief survey of recent advances in gas-phase collision dynamics studies using pulse radiolysis methods, the following two topics in our research programs are presented with emphasis on the superior advantages of the pulse radiolysis methods over the various methods of gas-phase collision dynamics, such as beam methods, swarm methods and flow methods. One of the topics is electron attachment to van der Waals molecules. The attachment rates of thermal electrons to O 2 and other molecules in dense gases have been measured in wide ranges of both gas temperatures and pressures, from which experimental evidence has been obtained for electron attachment to van der Waals molecules. The results have been compared with theories and discussed in terms of the effect of van der Waals interaction on the electron attachment resonance. The obtained conclusions have been related with investigations of electron attachment, solvation and localization in the condensed phase. The other is Penning ionization and its related processes. The rate constants for the de-excitation of He(2 1 P), He(2 3 S), Ne( 3 P 0 ), Ne( 3 P 1 ), Ne( 3 P 2 ), Ar( 1 P 1 ), Ar( 3 P 1 ), by atoms and molecules have been measured in the temperature range from 100 to 300 K, thus obtaining the collisional energy dependence of the de-excitation cross sections. The results are compared in detail with theories classified according to the excited rare gas atoms in the metastable and resonance states. (author)

  10. Rotational temperature measurement of NO gas using two-photon excitation spectrum

    Science.gov (United States)

    Ozaki, Tadao; Matsui, Yoshihiko; Ohsawa, Toshihiko

    1981-04-01

    The rotational temperature of nitric oxide gas has been measured by means of a single-beam two-photon excitation spectrum method using a pulsed continuously tunable dye laser. The nitric oxide gas was enclosed at about 40 Torr in a quartz cell which was put in an electric oven. The NO γ (0-0) band and R11+Q21 branches were used to obtain the two-photon excitation spectrum. The rotational temperatures were determined using the fact that molecules are distributed in the rotational levels according to the Boltzmann law. The temperature range was from room temperature to about 470 K. Observed temperatures were in good agreement with cell temperatures which were obtained by using a thermocouple.

  11. Resolving Gas-Phase Metallicity In Galaxies

    Science.gov (United States)

    Carton, David

    2017-06-01

    Chapter 2: As part of the Bluedisk survey we analyse the radial gas-phase metallicity profiles of 50 late-type galaxies. We compare the metallicity profiles of a sample of HI-rich galaxies against a control sample of HI-'normal' galaxies. We find the metallicity gradient of a galaxy to be strongly correlated with its HI mass fraction {M}{HI}) / {M}_{\\ast}). We note that some galaxies exhibit a steeper metallicity profile in the outer disc than in the inner disc. These galaxies are found in both the HI-rich and control samples. This contradicts a previous indication that these outer drops are exclusive to HI-rich galaxies. These effects are not driven by bars, although we do find some indication that barred galaxies have flatter metallicity profiles. By applying a simple analytical model we are able to account for the variety of metallicity profiles that the two samples present. The success of this model implies that the metallicity in these isolated galaxies may be in a local equilibrium, regulated by star formation. This insight could provide an explanation of the observed local mass-metallicity relation. Chapter 3 We present a method to recover the gas-phase metallicity gradients from integral field spectroscopic (IFS) observations of barely resolved galaxies. We take a forward modelling approach and compare our models to the observed spatial distribution of emission line fluxes, accounting for the degrading effects of seeing and spatial binning. The method is flexible and is not limited to particular emission lines or instruments. We test the model through comparison to synthetic observations and use downgraded observations of nearby galaxies to validate this work. As a proof of concept we also apply the model to real IFS observations of high-redshift galaxies. From our testing we show that the inferred metallicity gradients and central metallicities are fairly insensitive to the assumptions made in the model and that they are reliably recovered for galaxies

  12. Vibrational-rotational excitation: chemical reactions of vibrationally excited molecules

    International Nuclear Information System (INIS)

    Moore, C.B.; Smith, I.W.M.

    1979-03-01

    This review considers a limited number of systems, particularly gas-phase processes. Excited states and their preparation, direct bimolecular reactions, reactions of highly excited molecules, and reactions in condensed phases are discussed. Laser-induced isotope separation applications are mentioned briefly. 109 references

  13. Tuning excitation laser wavelength for secondary resonance in low-intensity phase-selective laser-induced breakdown spectroscopy for in-situ analytical measurement of nanoaerosols

    Science.gov (United States)

    Xiong, Gang; Li, Shuiqing; Tse, Stephen D.

    2018-02-01

    In recent years, a novel low-intensity phase-selective laser-induced breakdown spectroscopy (PS-LIBS) technique has been developed for unique elemental-composition identification of aerosolized nanoparticles, where only the solid-phase nanoparticles break down, forming nanoplasmas, without any surrounding gas-phase breakdown. Additional work has demonstrated that PS-LIBS emissions can be greatly enhanced with secondary resonant excitation by matching the excitation laser wavelength with an atomic transition line in the formed nanoplasma, thereby achieving low limits of detection. In this work, a tunable dye laser is employed to investigate the effects of excitation wavelength and irradiance on in-situ PS-LIBS measurements of TiO2 nanoaerosols. The enhancement factor by resonant excitation can be 220 times greater than that for non-resonant cases under similar conditions. Moreover, the emitted spectra are unique for the selected resonant transition lines for a given element, suggesting the potential to make precise phase-selective and analyte-selective measurements of nanoparticles in a multicomponent multiphase system. The enhancement factor by resonant excitation is highly sensitive to excitation laser wavelength, with narrow excitation spectral windows, i.e., 0.012 to 0.023 nm (FWHM, full width at half maximum) for Ti (I) neutral atomic lines, and 0.051 to 0.139 nm (FWHM) for Ti (II) single-ionized atomic lines. Boltzmann analysis of the emission intensities, temporal response of emissions, and emission dependence on excitation irradiance are investigated to understand aspects of the generated nanoplasmas such as temperature, local thermodynamic equilibrium (LTE), and excitation mechanism.

  14. The excitation of an independent-particle gas by a time dependent potential well

    Directory of Open Access Journals (Sweden)

    J. P. Błocki

    2010-09-01

    Full Text Available The order-to-chaos transition in the dynamics of independent classical particles gas was studied by means of the numerical simulations. The excitation of the gas for containers whose surfaces are rippled according to Legendre polynomials P2 , P3, P4 , P5 , P6 was followed for ten periods of oscillations. Spheroidal deformations were also considered. Poincare sections and Lyapunov exponents have been calculated showing different degrees of chaoticity depending on the shape and amplitude of oscillations. For 2 P polynomial the reaction of a gas to the periodic container deformation is mostly elastic as 2 P deformation especially for not very big deformations is almost like an integrable spheroid. For other polynomials the situation is more or less chaotic with a chaoticity increasing with the increasing order of the polynomial.

  15. Comparison of catalytic ethylene polymerization in slurry and gas phase

    NARCIS (Netherlands)

    Daftaribesheli, Majid

    2009-01-01

    Polyethylene (PE) with the annual consumption of 70 million tones in 2007 is mostly produced in slurry, gas-phase or combination of both processes. This work focuses on a comparison between the slurry and gas phase processes. Why does PE produced in theses two processes can show extremely different

  16. The study of excited oxygen molecule gas species production and quenching on thermal protection system materials

    Science.gov (United States)

    Nordine, Paul C.; Fujimoto, Gordon T.; Greene, Frank T.

    1987-01-01

    The detection of excited oxygen and ozone molecules formed by surface catalyzed oxygen atom recombination and reaction was investigated by laser induced fluorescence (LIF), molecular beam mass spectrometric (MBMS), and field ionization (FI) techniques. The experiment used partially dissociated oxygen flows from a microwave discharge at pressures in the range from 60 to 400 Pa or from an inductively coupled RF discharge at atmospheric pressure. The catalyst materials investigated were nickel and the reaction cured glass coating used for Space Shuttle reusable surface insulation tiles. Nonradiative loss processes for the laser excited states makes LIF detection of O2 difficult such that formation of excited oxygen molecules could not be detected in the flow from the microwave discharge or in the gaseous products of atom loss on nickel. MBMS experiments showed that ozone was a product of heterogeneous O atom loss on nickel and tile surfaces at low temperatures and that ozone is lost on these materials at elevated temperatures. FI was separately investigated as a method by which excited oxygen molecules may be conveniently detected. Partial O2 dissociation decreases the current produced by FI of the gas.

  17. Modeling the Phase Composition of Gas Condensate in Pipelines

    Science.gov (United States)

    Dudin, S. M.; Zemenkov, Yu D.; Shabarov, A. B.

    2016-10-01

    Gas condensate fields demonstrate a number of thermodynamic characteristics to be considered when they are developed, as well as when gas condensate is transported and processed. A complicated phase behavior of the gas condensate system, as well as the dependence of the extracted raw materials on the phase state of the deposit other conditions being equal, is a key aspect. Therefore, when designing gas condensate lines the crucial task is to select the most appropriate methods of calculating thermophysical properties and phase equilibrium of the transported gas condensate. The paper describes a physical-mathematical model of a gas-liquid flow in the gas condensate line. It was developed based on balance equations of conservation of mass, impulse and energy of the transported medium within the framework of a quasi-1D approach. Constitutive relationships are given separately, and practical recommendations on how to apply the research results are provided as well.

  18. Accounting for the contributions of topological excitations in phase transitions through dual actions

    International Nuclear Information System (INIS)

    Ramos, Rudnei O.

    2006-01-01

    Topological excitations are believed to play an important role in different areas of physics. For example, cases of topical interest are the study of contributions of nonhomogeneous field configurations, in particular those of topological nature (like kinks, vortices and monopoles) in phase transitions associated to spontaneous symmetry breaking, the use of topological excitations in dual models of QCD to understand properties of its vacuum and confinement through the condensation of magnetic monopoles and vortices and also the relevance of these nonhomogeneous type of configurations in cosmology, again associated to possible phase transitions that are expected to have happened in the early universe. Here we show a derivation of a model dual to the scalar Abelian Higgs model where its topological excitations, namely vortex-strings, become manifest and can be treated in a quantum field theory way. The contribution of these nontrivial vacuum excitations in the phase transition for the scalar Abelian Higgs model in a thermal background is then studied and the results interpreted from the computation of the partition function taking into account the vortice-strings in the functional integration. This is made possible from the derived dual action. The relevance of the obtained results in cosmology, the analogy with phase transitions in superconductors, the relevance also for the study of confinement and other extensions of our calculations are briefly discussed here. (author)

  19. Electron-Impact Excitation Cross Sections for Modeling Non-Equilibrium Gas

    Science.gov (United States)

    Huo, Winifred M.; Liu, Yen; Panesi, Marco; Munafo, Alessandro; Wray, Alan; Carbon, Duane F.

    2015-01-01

    In order to provide a database for modeling hypersonic entry in a partially ionized gas under non-equilibrium, the electron-impact excitation cross sections of atoms have been calculated using perturbation theory. The energy levels covered in the calculation are retrieved from the level list in the HyperRad code. The downstream flow-field is determined by solving a set of continuity equations for each component. The individual structure of each energy level is included. These equations are then complemented by the Euler system of equations. Finally, the radiation field is modeled by solving the radiative transfer equation.

  20. Phase space interrogation of the empirical response modes for seismically excited structures

    Science.gov (United States)

    Paul, Bibhas; George, Riya C.; Mishra, Sudib K.

    2017-07-01

    Conventional Phase Space Interrogation (PSI) for structural damage assessment relies on exciting the structure with low dimensional chaotic waveform, thereby, significantly limiting their applicability to large structures. The PSI technique is presently extended for structure subjected to seismic excitations. The high dimensionality of the phase space for seismic response(s) are overcome by the Empirical Mode Decomposition (EMD), decomposing the responses to a number of intrinsic low dimensional oscillatory modes, referred as Intrinsic Mode Functions (IMFs). Along with their low dimensionality, a few IMFs, retain sufficient information of the system dynamics to reflect the damage induced changes. The mutually conflicting nature of low-dimensionality and the sufficiency of dynamic information are taken care by the optimal choice of the IMF(s), which is shown to be the third/fourth IMFs. The optimal IMF(s) are employed for the reconstruction of the Phase space attractor following Taken's embedding theorem. The widely referred Changes in Phase Space Topology (CPST) feature is then employed on these Phase portrait(s) to derive the damage sensitive feature, referred as the CPST of the IMFs (CPST-IMF). The legitimacy of the CPST-IMF is established as a damage sensitive feature by assessing its variation with a number of damage scenarios benchmarked in the IASC-ASCE building. The damage localization capability, remarkable tolerance to noise contamination and the robustness under different seismic excitations of the feature are demonstrated.

  1. Regular and irregular patterns of self-localized excitation in arrays of coupled phase oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Wolfrum, Matthias; Omel' chenko, Oleh E. [Weierstrass Institute, Mohrenstrasse 39, Berlin 10117 (Germany); Sieber, Jan [College of Engineering, Mathematics and Physical Sciences, University of Exeter, North Park Road, Exeter EX4 4QF (United Kingdom)

    2015-05-15

    We study a system of phase oscillators with nonlocal coupling in a ring that supports self-organized patterns of coherence and incoherence, called chimera states. Introducing a global feedback loop, connecting the phase lag to the order parameter, we can observe chimera states also for systems with a small number of oscillators. Numerical simulations show a huge variety of regular and irregular patterns composed of localized phase slipping events of single oscillators. Using methods of classical finite dimensional chaos and bifurcation theory, we can identify the emergence of chaotic chimera states as a result of transitions to chaos via period doubling cascades, torus breakup, and intermittency. We can explain the observed phenomena by a mechanism of self-modulated excitability in a discrete excitable medium.

  2. Asymptotic theory of neutral stability of the Couette flow of a vibrationally excited gas

    Science.gov (United States)

    Grigor'ev, Yu. N.; Ershov, I. V.

    2017-01-01

    An asymptotic theory of the neutral stability curve for a supersonic plane Couette flow of a vibrationally excited gas is developed. The initial mathematical model consists of equations of two-temperature viscous gas dynamics, which are used to derive a spectral problem for a linear system of eighth-order ordinary differential equations within the framework of the classical linear stability theory. Unified transformations of the system for all shear flows are performed in accordance with the classical Lin scheme. The problem is reduced to an algebraic secular equation with separation into the "inviscid" and "viscous" parts, which is solved numerically. It is shown that the thus-calculated neutral stability curves agree well with the previously obtained results of the direct numerical solution of the original spectral problem. In particular, the critical Reynolds number increases with excitation enhancement, and the neutral stability curve is shifted toward the domain of higher wave numbers. This is also confirmed by means of solving an asymptotic equation for the critical Reynolds number at the Mach number M ≤ 4.

  3. Atomic and molecular gas phase spectrometry

    Science.gov (United States)

    Winefordner, J. D.

    1985-10-01

    The major goals of this research have been to develop diagnostical spectroscopic methods for measuring spatial/temporal temperatures and species of combustion flames and plasmas and to develop sensitive, selective, precise, reliable, rapid spectrometric methods of trace analysis of elements present in jet engine lubricating oils, metallurgical samples, and engine exhausts. The diagnostical approaches have been based upon the measurement of metal probes introduced into the flame or plasmas and the measurement of OH in flames. The measurement approaches have involved the use of laser-excited fluorescence, saturated absorption, polarization, and linear absorption. The spatial resolution in most studies is less than 1 cu mm and the temporal resolution is less than 10 ns with the use of pulsed lasers. Single pulse temperature and species measurements have also been carried out. Other diagnostical studies have involved the measurement of collisional redistribution of radiatively excited levels of Na and Tl in acetylene/02/Ar flames and the measurement of lifetimes and quantum efficiencies of atoms and ions in the inductively coupled plasmas, ICP. The latter studies indicate that the high electron number densities in ICPs are not efficient quenchers of excited atoms/ions. Temperatures of microwave atmospheric plasmas produced capacitatively and cool metastable N2 discharge produced by a dielectric discharge have also been measured.

  4. Restricted second random phase approximations and Tamm-Dancoff approximations for electronic excitation energy calculations

    International Nuclear Information System (INIS)

    Peng, Degao; Yang, Yang; Zhang, Peng; Yang, Weitao

    2014-01-01

    In this article, we develop systematically second random phase approximations (RPA) and Tamm-Dancoff approximations (TDA) of particle-hole and particle-particle channels for calculating molecular excitation energies. The second particle-hole RPA/TDA can capture double excitations missed by the particle-hole RPA/TDA and time-dependent density-functional theory (TDDFT), while the second particle-particle RPA/TDA recovers non-highest-occupied-molecular-orbital excitations missed by the particle-particle RPA/TDA. With proper orbital restrictions, these restricted second RPAs and TDAs have a formal scaling of only O(N 4 ). The restricted versions of second RPAs and TDAs are tested with various small molecules to show some positive results. Data suggest that the restricted second particle-hole TDA (r2ph-TDA) has the best overall performance with a correlation coefficient similar to TDDFT, but with a larger negative bias. The negative bias of the r2ph-TDA may be induced by the unaccounted ground state correlation energy to be investigated further. Overall, the r2ph-TDA is recommended to study systems with both single and some low-lying double excitations with a moderate accuracy. Some expressions on excited state property evaluations, such as 〈S ^2 〉 are also developed and tested

  5. Restricted second random phase approximations and Tamm-Dancoff approximations for electronic excitation energy calculations

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Degao; Yang, Yang; Zhang, Peng [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Yang, Weitao, E-mail: weitao.yang@duke.edu [Department of Chemistry and Department of Physics, Duke University, Durham, North Carolina 27708 (United States)

    2014-12-07

    In this article, we develop systematically second random phase approximations (RPA) and Tamm-Dancoff approximations (TDA) of particle-hole and particle-particle channels for calculating molecular excitation energies. The second particle-hole RPA/TDA can capture double excitations missed by the particle-hole RPA/TDA and time-dependent density-functional theory (TDDFT), while the second particle-particle RPA/TDA recovers non-highest-occupied-molecular-orbital excitations missed by the particle-particle RPA/TDA. With proper orbital restrictions, these restricted second RPAs and TDAs have a formal scaling of only O(N{sup 4}). The restricted versions of second RPAs and TDAs are tested with various small molecules to show some positive results. Data suggest that the restricted second particle-hole TDA (r2ph-TDA) has the best overall performance with a correlation coefficient similar to TDDFT, but with a larger negative bias. The negative bias of the r2ph-TDA may be induced by the unaccounted ground state correlation energy to be investigated further. Overall, the r2ph-TDA is recommended to study systems with both single and some low-lying double excitations with a moderate accuracy. Some expressions on excited state property evaluations, such as 〈S{sup ^2}〉 are also developed and tested.

  6. Random excitation forces in tube bundles subjected to two-phase cross-flow

    International Nuclear Information System (INIS)

    Taylor, C.E.; Pettigrew, M.J.; Currie, I.G.

    1996-01-01

    Data from two experimental programs have been analyzed to determine the characteristics of the random excitation forces associated with two-phase cross-flow in tube bundles. Large-scale air-water flow loops in France and Canada were used to generate the data. Tests were carried out on cantilevered, clamped-pinned, and clamped-clamped tubes in normal-square, parallel-triangular, and normal-triangular configurations. Either strain gages or force transducers were used to measure the vibration response of a centrally located tube as the tue array was subjected to a wide range of void fractions and flow rates. Power spectra were analyzed to determine the effect of parameters such as tube diameter, frequency, flow rate, void fraction, and flow regime on the random excitation forces. Normalized expressions for the excitation force power spectra were found to be flow-regime dependent. In the churn flow regime, flow rate and void fraction had very little effect on the magnitude of the excitation forces. In the bubble-plug flow regime, the excitation forces increased rapidly with flow rate and void fraction

  7. Wigner Distribution Functions as a Tool for Studying Gas Phase Alkali Metal Plus Noble Gas Collisions

    Science.gov (United States)

    2014-03-27

    WIGNER DISTRIBUTION FUNCTIONS AS A TOOL FOR STUDYING GAS PHASE ALKALI METAL PLUS NOBLE GAS COLLISIONS THESIS Keith A. Wyman, Second Lieutenant, USAF...the U.S. Government and is not subject to copyright protection in the United States. AFIT-ENP-14-M-39 WIGNER DISTRIBUTION FUNCTIONS AS A TOOL FOR...APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT-ENP-14-M-39 WIGNER DISTRIBUTION FUNCTIONS AS A TOOL FOR STUDYING GAS PHASE ALKALI METAL PLUS

  8. Heat capacity for systems with excited-state quantum phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Cejnar, Pavel; Stránský, Pavel, E-mail: stransky@ipnp.troja.mff.cuni.cz

    2017-03-18

    Heat capacities of model systems with finite numbers of effective degrees of freedom are evaluated using canonical and microcanonical thermodynamics. Discrepancies between both approaches, which are observed even in the infinite-size limit, are particularly large in systems that exhibit an excited-state quantum phase transition. The corresponding irregularity of the spectrum generates a singularity in the microcanonical heat capacity and affects smoothly the canonical heat capacity. - Highlights: • Thermodynamics of systems with excited-state quantum phase transitions • ESQPT-generated singularities of the microcanonical heat capacity • Non-monotonous dependences of the canonical heat capacity • Discord between canonical and microcanonical pictures in the infinite-size limit.

  9. Reticulated Vitreous Carbon Electrodes for Gas Phase Pulsed Corona Reactors

    National Research Council Canada - National Science Library

    Locke, B

    1998-01-01

    A new design for gas phase pulsed corona reactors incorporating reticulated vitreous carbon electrodes is demonstrated to be effective for the removal of nitrogen oxides from synthetic air mixtures...

  10. GAS PHASE ION CHEMISTRY OF COUMARINS: AB INITIO ...

    African Journals Online (AJOL)

    B. S. Chandravanshi

    The gas phase ion chemistry of coumarins using electron ionization (EI), positive chemical ionization (PCI) and ... Figure 1. Generic chemical structures of the coumarins in this study. ..... Part of this work was conducted using the resources of ...

  11. Reticulated Vitreous Carbon Electrodes for Gas Phase Pulsed Corona Reactors

    National Research Council Canada - National Science Library

    LOCKE, B

    1999-01-01

    A new design for gas phase pulsed corona reactors incorporating reticulated vitreous carbon electrodes is demonstrated to be effective for the removal of nitrogen oxides from synthetic air mixtures...

  12. Diode Laser Raman Scattering Prototype Gas-Phase Environmental Monitoring

    National Research Council Canada - National Science Library

    Benner, Robert

    1999-01-01

    We proposed developing a diode-laser-based, full spectrum Raman scattering instrument incorporating a multipass, external cavity enhancement cell for full spectrum, gas phase analysis of environmental pollutants...

  13. Laser spectroscopy and gas-phase chemistry in CVD

    International Nuclear Information System (INIS)

    Ho, P.; Breiland, W.G.; Coltrin, M.E.

    1986-01-01

    The experimental work involves the use of laser spectroscopic techniques for in situ measurements on the gas phase in a chemical vapor deposition reactor. The theoretical part of the program consists of a computer model of the coupled fluid mechanics and gas-phase chemical kinetics of silane decomposition and subsequent reactions of intermediate species. The laser measurements provide extensive data for thoroughly testing the predictive capabilities of the model

  14. Comparison of catalytic ethylene polymerization in slurry and gas phase

    OpenAIRE

    Daftaribesheli, Majid

    2009-01-01

    Polyethylene (PE) with the annual consumption of 70 million tones in 2007 is mostly produced in slurry, gas-phase or combination of both processes. This work focuses on a comparison between the slurry and gas phase processes. Why does PE produced in theses two processes can show extremely different properties and extremely different reaction behaviour even if the same Ziegler-Natta (ZN) catalyst is used? Generally, it is known that the reason can be found in the differences of local condition...

  15. Absence of phase-dependent noise in time-domain reflectivity studies of impulsively excited phonons

    KAUST Repository

    Hussain, A.

    2010-06-17

    There have been several reports of phase-dependent noise in time-domain reflectivity studies of optical phonons excited by femtosecond laser pulses in semiconductors, semimetals, and superconductors. It was suggested that such behavior is associated with the creation of squeezed phonon states although there is no theoretical model that directly supports such a proposal. We have experimentally re-examined the studies of phonons in bismuth and gallium arsenide, and find no evidence of any phase-dependent noise signature associated with the phonons. We place an upper limit on any such noise at least 40–50 dB lower than previously reported.

  16. Absence of phase-dependent noise in time-domain reflectivity studies of impulsively excited phonons

    KAUST Repository

    Hussain, A.; Andrews, S. R.

    2010-01-01

    There have been several reports of phase-dependent noise in time-domain reflectivity studies of optical phonons excited by femtosecond laser pulses in semiconductors, semimetals, and superconductors. It was suggested that such behavior is associated with the creation of squeezed phonon states although there is no theoretical model that directly supports such a proposal. We have experimentally re-examined the studies of phonons in bismuth and gallium arsenide, and find no evidence of any phase-dependent noise signature associated with the phonons. We place an upper limit on any such noise at least 40–50 dB lower than previously reported.

  17. Electron spectrometer for gas-phase spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bozek, J.D.; Schlachter, A.S. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    An electron spectrometer for high-resolution spectroscopy of gaseous samples using synchrotron radiation has been designed and constructed. The spectrometer consists of a gas cell, cylindrical electrostatic lens, spherical-sector electron energy analyzer, position-sensitive detector and associated power supplies, electronics and vacuum pumps. Details of the spectrometer design are presented together with some representative spectra.

  18. Phase transitions and spin excitations of spin-1 bosons in optical lattice

    Science.gov (United States)

    Zhu, Min-Jie; Zhao, Bo

    2018-03-01

    For spin-1 bosonic system trapped in optical lattice, we investigate two main problems, including MI-SF phase transition and magnetic phase separations in MI phase, with extended standard basis operator (SBO) method. For both ferromagnetic (U2 0) systems, we analytically figure out the symmetry properties in Mott-insulator and superfluid phases, which would provide a deeper insight into the MI-SF phase transition process. Then by applying self-consistent approach to the method, we include the effect of quantum and thermal fluctuations and derive the MI-SF transition phase diagram, which is in quantitative agreement with recent Monte-Carlo simulation at zero temperature, and at finite temperature, we find the underestimation of finite-temperature-effect in the mean-field approximation method. If we further consider the spin excitations in the insulating states of spin-1 system in external field, distinct spin phases are expected. Therefore, in the Mott lobes with n = 1 and n = 2 atoms per site, we give analytical and numerical boundaries of the singlet, nematic, partially magnetic and ferromagnetic phases in the magnetic phase diagrams.

  19. Gas hydrate phase equilibria measurement techniques and phase rule considerations

    International Nuclear Information System (INIS)

    Beltran, Juan G.; Bruusgaard, Hallvard; Servio, Phillip

    2012-01-01

    Highlights: → Inconsistencies found in hydrate literature. → Clarification to the number of variables needed to satisfy and justify equilibrium data. → Application of phase rule to mixed hydrate systems. → Thermodynamically consistent format to present data. - Abstract: A brief review of the Gibbs phase rule for non-reacting systems and its correct application to clathrate hydrates is presented. Clarification is provided for a common mistake found in hydrate phase-equilibria literature, whereby initial compositions are used as intensive variables to satisfy the Gibbs phase rule instead of the equilibrium values. The system of (methane + carbon dioxide + water) under (hydrate + liquid + vapor) equilibrium is used as a case study to illustrate key points and suggestions to improve experimental techniques are proposed.

  20. Device to remove hydrogen isotopes from a gas phase

    International Nuclear Information System (INIS)

    Morlock, G.; Wiesemes, J.; Bachner, D.

    1977-01-01

    The device described here guarantees the selective removal of hydrogen isotopes from gas phases in order to prevent the occurence of explosive H 2 gas mixtures, or to separate off radioactive tritium in nuclear plants from the gas phase. It consists of a closed container whose walls are selectively penetrable by hydrogen isotopes. It is simultaneously filled compactly and presssure-resistant with a metal bulk (e.g. powder, sponges or the like of titanium or other hydrogen isotope binding metal). Walling and bulk are maintained at suitable working temperatures by means of a system according to the Peltier effect. The whole thing is safeguarded by protective walling. (RB) [de

  1. FORTRAN program for calculating liquid-phase and gas-phase thermal diffusion column coefficients

    International Nuclear Information System (INIS)

    Rutherford, W.M.

    1980-01-01

    A computer program (COLCO) was developed for calculating thermal diffusion column coefficients from theory. The program, which is written in FORTRAN IV, can be used for both liquid-phase and gas-phase thermal diffusion columns. Column coefficients for the gas phase can be based on gas properties calculated from kinetic theory using tables of omega integrals or on tables of compiled physical properties as functions of temperature. Column coefficients for the liquid phase can be based on compiled physical property tables. Program listings, test data, sample output, and users manual are supplied for appendices

  2. CHAOS. III. GAS-PHASE ABUNDANCES IN NGC 5457

    Energy Technology Data Exchange (ETDEWEB)

    Croxall, Kevin V.; Pogge, Richard W. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Berg, Danielle A. [Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin Milwaukee, 1900 East Kenwood Boulevard, Milwaukee, WI 53211 (United States); Skillman, Evan D. [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Moustakas, John [Department of Physics and Astronomy, Siena College, 515 Loudon Road, Loudonville, NY 12211 (United States)

    2016-10-10

    We present Large Binocular Telescope observations of 109 H ii regions in NGC 5457 (M101) obtained with the Multi-Object Double Spectrograph. We have robust measurements of one or more temperature-sensitive auroral emission lines for 74 H ii regions, permitting the measurement of “direct” gas-phase abundances. Comparing the temperatures derived from the different ionic species, we find: (1) strong correlations of T [N ii] with T [S iii] and T [O iii], consistent with little or no intrinsic scatter; (2) a correlation of T [S iii] with T [O iii], but with significant intrinsic dispersion; (3) overall agreement between T [N ii], T [S ii], and T [O ii], as expected, but with significant outliers; (4) the correlations of T [N ii] with T [S iii] and T [O iii] match the predictions of photoionization modeling while the correlation of T [S iii] with T [O iii] is offset from the prediction of photoionization modeling. Based on these observations, which include significantly more observations of lower excitation H ii regions, missing in many analyses, we inspect the commonly used ionization correction factors (ICFs) for unobserved ionic species and propose new empirical ICFs for S and Ar. We have discovered an unexpected population of H ii regions with a significant offset to low values in Ne/O, which defies explanation. We derive radial gradients in O/H and N/O which agree with previous studies. Our large observational database allows us to examine the dispersion in abundances, and we find intrinsic dispersions of 0.074 ± 0.009 in O/H and 0.095 ± 0.009 in N/O (at a given radius). We stress that this measurement of the intrinsic dispersion comes exclusively from direct abundance measurements of H ii regions in NGC 5457.

  3. Kinetics of the gas-phase tritium oxidation reaction

    International Nuclear Information System (INIS)

    Failor, R.A.

    1989-01-01

    Homogeneous gas-phase kinetics of tritium oxidation (2T 2 + O 2 →2T 2 O) have been studied with a model that accounts explicitly for radiolysis of the major species and the kinetics of the subsequent reactions of ionic, excited-state, and neutral species. Results from model calculations are given for 10 -4 -1.0 mol% T 2 in O 2 (298 K, 1 atm). As the reaction evolves three different mechanisms control T 2 O production, each with a different overall rate expression and a different order with respect to the T 2 concentration. The effects of self-radiolysis of pure T 2 on the tritium oxidation reaction were calculated. Tritium atoms, the primary product of T 2 self-radiolysis, altered the oxidation mechanism only during the first few seconds following the initiation of the T 2 -O 2 reaction. Ozone, an important intermediate in T 2 oxidation, was monitored in-situ by U.V. absorption spectroscopy for 0.01-1.0 mol% T 2 an 1 atm O 2 . The shape of the experimental ozone time profile agreed with the model predictions. As predicted, the measured initial rate of ozone production varied linearly with initial T 2 concentration ([T 2 ] 0.6 o ), but at an initial rate one-third the predicted value. The steady-state ozone concentration ([O 3 ]ss) was predicted to be dependent on [T 2 ] 0.3 o , but the measured value was [T 2 ] 0.6 o , resulting in four times higher [O 3 ]ss than predicted for a 1.0% T 2 -O 2 mixture. Adding H 2 to the T 2 -O 2 mixture, to provide insight into the differences between the radiolytic and chemical behavior of the tritium, produced a greater decrease in [O 3 ]ss than predicted. Adjusting the reaction cell surface-to-volume ratio showed implications of minor surface removal of ozone

  4. Dissociative attachment reactions of electrons with gas phase superacids

    International Nuclear Information System (INIS)

    Liu, X.

    1992-01-01

    Using the flowing afterglow Langmuir probe (FALP) technique, dissociative attachment coefficients β for reactions of electrons with gas phase superacids HCo(PF 3 ) 4 , HRh(PF 3 ) 4 and carbonyl hydride complexes HMn(CO) 5 , HRe(CO) 5 have been determined under thermal conditions over the approximate temperature range 300∼550 K. The superacids react relatively slowly ( max ) with free electrons in a thermal plasma, and the values of β obtained this far do not show a correlation between acidity and β. The pioneer researchers in this field had speculated that any superacid would be a rapid attacher of electrons; it was found that this speculation is not true in general. The product distribution of electron attachment reaction to HCo(PF 3 ) 4 was found to be independent of temperature even though the β[HCo(PF 3 ) 4 ] increases with temperature. This proposes that the electron attachment process occurs well before the excited complex dissociates. In addition, the activation energy of HCo(PF 3 ) 4 for electron attachment has been derived from the Arrhenius plots. The carbonyl hydride complexes, HMn(CO) 5 and HRe(CO) 5 , react relatively rapidly (>1/4 of β max ) with free electrons in thermal plasma. This indicates that these reactions cannot be significantly endothermic. Observation of rapid attachment for these non-superacids shows that the Mn-CO and Re-CO bonds are weaker than the Mn-H and Re-H bonds, respectively. Comparisons between the carbonyl and trifluorophosphine cases implies that fast electron capture is related more to the CO ligand than to the transition-metal species

  5. Catalytic combustion in gas stoves - Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Hjelm, Anna-Karin [CATATOR AB, Lund (Sweden)

    2003-06-01

    Several independent studies show that gas stoves to some degree contribute to the indoor emissions of NO{sub x} especially in situations were the ventilation flow is poor. The peak-NO{sub x} concentrations can reach several hundred ppb but the integral concentration seldom exceeds about 20 - 50 ppb, which corresponds to an indoor-outdoor ratio of about 1 - 2.5. Epidemiological studies indicate increasing problems with respiratory symptoms in sensitive people at concentrations as low as 15 ppb of NO{sub 2}. Consequently, the NO{sub x}-concentration in homes where gas stoves are used is high enough to cause health effects. However, in situations where the ventilation flow is high (utilisation of ventilation hoods) the NO{sub x}-emissions are not likely to cause any health problems. This study has been aimed at investigating the possibilities to reduce the NO{sub x} emissions from gas stoves by replacing the conventional flame combustion with catalytic combustion. The investigation is requested by Swedish Gas Center, and is a following-up work of an earlier conducted feasibility study presented in April-2002. The present investigation reports on the possibility to use cheap and simple retro-fit catalytic design suggestions for traditional gas stoves. Experiments have been conducted with both natural and town gas, and parameters such as emissions of NO{sub x}, CO and unburned fuel gas and thermal efficiency, etc, have been examined and are discussed. The results show that it is possible to reduce the NO{sub x} emissions up to 80% by a simple retro-fit installation, without decreasing the thermal efficiency of the cooking plate. The measured source strengths correspond to indoor NO{sub x} concentrations that are below or equal to the average outdoor concentration, implying that no additional detrimental health effects are probable. The drawback of the suggested installations is that the concentration of CO and in some cases also CH{sub 4} are increased in the flue gases

  6. Vibration mode and vibration shape under excitation of a three phase model transformer core

    Science.gov (United States)

    Okabe, Seiji; Ishigaki, Yusuke; Omura, Takeshi

    2018-04-01

    Structural vibration characteristics and vibration shapes under three-phase excitation of a archetype transformer core were investigated to consider their influences on transformer noise. Acoustic noise and vibration behavior were measured in a three-limb model transformer core. Experimental modal analysis by impact test was performed. The vibration shapes were measured by a laser scanning vibrometer at different exciting frequencies. Vibration amplitude of the core in out-of-plane direction were relatively larger than those in other two in-plane directions. It was consistent with the result that the frequency response function of the core in out-of-plane direction was larger by about 20 dB or more than those in in-plane directions. There were many vibration modes having bending deformation of limbs in out-of-plane direction. The vibration shapes of the core when excited at 50 Hz and 60 Hz were almost the same because the fundamental frequencies of the vibration were not close to the resonance frequencies. When excitation frequency was 69 Hz which was half of one of the resonance frequencies, the vibration shape changed to the one similar to the resonance vibration mode. Existence of many vibration modes in out-of-plane direction of the core was presumed to be a reason why frequency characteristics of magnetostriction and transformer noise do not coincide.

  7. HIGHLY EXCITED H2 IN HERBIG–HARO 7: FORMATION PUMPING IN SHOCKED MOLECULAR GAS?

    International Nuclear Information System (INIS)

    Pike, R. E.; Geballe, T. R.; Burton, M. G.; Chrysostomou, A.

    2016-01-01

    We have obtained K -band spectra at R ∼ 5000 and an angular resolution of 0.″3 of a section of the Herbig–Haro 7 (HH7) bow shock, using the Near-Infrared Integral Field Spectrograph at Gemini North. Present in the portion of the data cube corresponding to the brightest part of the bow shock are emission lines of H 2 with upper state energies ranging from ∼6000 K to the dissociation energy of H 2 , ∼50,000 K. Because of low signal-to-noise ratios, the highest excitation lines cannot be easily seen elsewhere in the observed region. However, excitation temperatures, measured throughout much of the observed region using lines from levels as high as 25,000 K, are a strong function of upper level energy, indicating that the very highest levels are populated throughout. The level populations in the brightest region are well fit by a two-temperature model, with 98.5% of the emitting gas at T = 1800 K and 1.5% at T = 5200 K. The bulk of the H 2 line emission in HH7, from the 1800 K gas, has previously been well-modeled by a continuous shock, but the 5200 K cozmponent is inconsistent with standalone standard continuous shock models. We discuss various possible origins for the hot component and suggest that this component is H 2 newly reformed on dust grains and then ejected from them, presumably following dissociation of some of the H 2 by the shock.

  8. Elementary excitations and the phase transition in the bimodal Ising spin glass model

    International Nuclear Information System (INIS)

    Jinuntuya, N; Poulter, J

    2012-01-01

    We show how the nature of the phase transition in the two-dimensional bimodal Ising spin glass model can be understood in terms of elementary excitations. Although the energy gap with the ground state is expected to be 4J in the ferromagnetic phase, a gap 2J is in fact found if the finite lattice is wound around a cylinder of odd circumference L. This 2J gap is really a finite size effect that should not occur in the thermodynamic limit of the ferromagnet. The spatial influence of the frustration must be limited and not wrap around the system if L is large enough. In essence, the absence of 2J excitations defines the ferromagnetic phase without recourse to calculating the magnetization or investigating the system response to domain wall defects. This study directly investigates the response to temperature. We also estimate the defect concentration where the phase transition to the spin glass state occurs. The value p c = 0.1045(11) is in reasonable agreement with the literature

  9. Probing the nuclear liquid-gas phase transition

    International Nuclear Information System (INIS)

    Pochodzalla, J.; Moehlenkamp, T.; Rubehn, T.; Schuettauf, A.; Zude, E.; Begemann-Blaich, M.; Blaich, T.; Emling, H.; Ferrero, A.; Kunze, W.D.; Lindenstruth, V.; Lynen, U.; Moroni, W.; Ocker, B.; Schwarz, C.; Seidel, W.; Serfling, V.; Trzcinski, A.; Tucholski, A.; Verde, G.

    1995-02-01

    Fragment distributions resulting from Au+Au collisions at an incident energy of E/A=600 MeV are studied. From the measured fragment and neutron distributions the mass and the excitation energy of the decaying pre-fragments were determined. A temperature scale was derived from observed yield ratios of He and Li isotopes. The relation between this isotope temperature and the excitation energy of the system exhibits a behavior which is expected for a phase transition. The nuclear vapor regime takes over at an excitation energy of 10 MeV per nucleon, a temperature of 5 MeV and may be characterized by a density of 0.15-0.3 normal nuclear density. (orig.)

  10. ICR studies of some anionic gas phase reactions and FTICR software design

    International Nuclear Information System (INIS)

    Noest, A.J.

    1983-01-01

    This thesis consists of two parts. Part one (Chs. 1-5) reports experimental results from mostly drift-cell ICR studies of negative ion-molecule reactions; part two (Chs. 6-11) concerns the design of software for an FTICR instrument. The author discusses successively: 1. ion cyclotron resonance spectrometry; 2. the gas phase allyl anion; 3. the (M-H) and (M-H2) anions from acetone; 4. negative ion-molecule reactions of aliphatic nitrites studied by cyclotron resonance; 5. homoconjugation versus charge-dipole interaction effects in the stabilization of carbanions in the gas phase; 6. the Fourier Transform ICR method; 7. the FTICR-software; 8. an efficient adaptive matcher filter for fast transient signals; 9. reduction of spectral peak height errors by time-domain weighing; 10. Chirp excitation; 11. Compact data storage. The book concludes with a Dutch and English summary (G.J.P.)

  11. Exploring the Photoreduction of Au(III) Complexes in the Gas-Phase

    Science.gov (United States)

    Marcum, Jesse C.; Kaufman, Sydney H.; Weber, J. Mathias

    2010-06-01

    We have used photodissociation spectroscopy to probe the electronic structure and photoreduction of Au(III) in gas-phase complexes containing Cl- and OH-. The gas-phase electronic spectrum of [AuCl_4]- closely resembles the aqueous solution spectrum, showing a lack of strong solvatochromic shifts. Substitution of Cl- ligands with OH- results in a strong blue shift, in agreement with ligand-field theory. Upon excitation, [AuCl_4]- can dissociate by loss of either one or two neutral Cl atoms, resulting in the reduction of gold from Au(III) to Au(II) and Au(I) respectively. The hydroxide substituted complex, [AuCl_2(OH)_2]-, demonstrates similar behavior but the only observable fragment channel is the loss of two neutral OH ligands, leading only to Au(I).

  12. Ab initio treatment of gas phase GeO{sup 2+} doubly charged ion

    Energy Technology Data Exchange (ETDEWEB)

    Mogren Al Mogren, M. [Chemistry Department, Faculty of Science, King Saud University, PO Box 2455, Riyadh 11451 (Saudi Arabia); Ben Abdallah, D. [Laboratoire de Spectroscopie Atomique, Moléculaire et Applications – LSAMA, Université de Tunis, Tunis (Tunisia); Department of General Studies, Riyadh Corporation of Technology, Technical and Vocational Training Corporation, PO Box 42826, Riyadh 11551 (Saudi Arabia); Hochlaf, M., E-mail: hochlaf@univ-mlv.fr [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France)

    2015-01-13

    Highlights: • Theoretical investigation of the novel gas-phase molecular species GeO{sup 2+}. • Spectroscopic parameters of this dication in its electronic ground and exited states. • Theoretical double ionization spectrum of GeO. - Abstract: Using multi reference configuration interaction methodology in connection with a large basis set, we show that GeO{sup 2+} is a metastable species either in the ground or in the electronically excited states. This confirms the observation of this dication in gas phase by mass spectrometry. In addition, we derived a set of accurate spectroscopic terms for GeO{sup 2+} bound states. At the MRCI/aug-cc-pV5Z level of theory, the adiabatic double ionization energy of GeO is computed to be ∼28.93 eV.

  13. Microfabricated Gas Phase Chemical Analysis Systems

    International Nuclear Information System (INIS)

    FRYE-MASON, GREGORY CHARLES; HELLER, EDWIN J.; HIETALA, VINCENT M.; KOTTENSTETTE, RICHARD; LEWIS, PATRICK R.; MANGINELL, RONALD P.; MATZKE, CAROLYN M.; WONG, CHUNGNIN C.

    1999-01-01

    A portable, autonomous, hand-held chemical laboratory ((micro)ChemLab(trademark)) is being developed for trace detection (ppb) of chemical warfare (CW) agents and explosives in real-world environments containing high concentrations of interfering compounds. Microfabrication is utilized to provide miniature, low-power components that are characterized by rapid, sensitive and selective response. Sensitivity and selectivity are enhanced using two parallel analysis channels, each containing the sequential connection of a front-end sample collector/concentrator, a gas chromatographic (GC) separator, and a surface acoustic wave (SAW) detector. Component design and fabrication and system performance are described

  14. SVOC partitioning between the gas phase and settled dust indoors

    Science.gov (United States)

    Weschler, Charles J.; Nazaroff, William W.

    2010-09-01

    Semivolatile organic compounds (SVOCs) are a major class of indoor pollutants. Understanding SVOC partitioning between the gas phase and settled dust is important for characterizing the fate of these species indoors and the pathways by which humans are exposed to them. Such knowledge also helps in crafting measurement programs for epidemiological studies designed to probe potential associations between exposure to these compounds and adverse health effects. In this paper, we analyze published data from nineteen studies that cumulatively report measurements of dustborne and airborne SVOCs in more than a thousand buildings, mostly residences, in seven countries. In aggregate, measured median data are reported in these studies for 66 different SVOCs whose octanol-air partition coefficients ( Koa) span more than five orders of magnitude. We use these data to test a simple equilibrium model for estimating the partitioning of an SVOC between the gas phase and settled dust indoors. The results demonstrate, in central tendency, that a compound's octanol-air partition coefficient is a strong predictor of its abundance in settled dust relative to its gas phase concentration. Using median measured results for each SVOC in each study, dustborne mass fractions predicted using Koa and gas-phase concentrations correlate reasonably well with measured dustborne mass fractions ( R2 = 0.76). Combined with theoretical understanding of SVOC partitioning kinetics, the empirical evidence also suggests that for SVOCs with high Koa values, the mass fraction in settled dust may not have sufficient time to equilibrate with the gas phase concentration.

  15. Calculation of Ground State Rotational Populations for Kinetic Gas Homonuclear Diatomic Molecules including Electron-Impact Excitation and Wall Collisions

    International Nuclear Information System (INIS)

    Farley, David R.

    2010-01-01

    A model has been developed to calculate the ground-state rotational populations of homonuclear diatomic molecules in kinetic gases, including the effects of electron-impact excitation, wall collisions, and gas feed rate. The equations are exact within the accuracy of the cross sections used and of the assumed equilibrating effect of wall collisions. It is found that the inflow of feed gas and equilibrating wall collisions can significantly affect the rotational distribution in competition with non-equilibrating electron-impact effects. The resulting steady-state rotational distributions are generally Boltzmann for N (ge) 3, with a rotational temperature between the wall and feed gas temperatures. The N = 0,1,2 rotational level populations depend sensitively on the relative rates of electron-impact excitation versus wall collision and gas feed rates.

  16. Coupled spin and charge collective excitations in a spin polarized electron gas

    International Nuclear Information System (INIS)

    Marinescu, D.C.; Quinn, J.J.; Yi, K.S.

    1997-01-01

    The charge and longitudinal spin responses induced in a spin polarized quantum well by a weak electromagnetic field are investigated within the framework of the linear response theory. The authors evaluate the excitation frequencies for the intra- and inter-subband transitions of the collective charge and longitudinal spin density oscillations including many-body corrections beyond the random phase approximation through the spin dependent local field factors, G σ ± (q,ω). An equation-of-motion method was used to obtain these corrections in the limit of long wavelengths, and the results are given in terms of the equilibrium pair correlation function. The finite degree of spin polarization is shown to introduce coupling between the charge and spin density modes, in contrast with the result for an unpolarized system

  17. Nucleation and dissociation of nano-particles in gas phase; Nucleation et evaporation de nanoparticules en phase gazeuse

    Energy Technology Data Exchange (ETDEWEB)

    Feiden, P

    2007-09-15

    This work deals with the study of nano-particles formation in gas phase and their dissociation pathways after an optical excitation. The clusters formation decomposes in two steps: a seed is formed (nucleation phase) and sticks atoms during its propagation in a sodium atomic vapor (growth phase). Those two steps have been observed separately for homogeneous Na{sub n} and heterogeneous Na{sub n}X particles (X = (NaOH){sub 2} or (Na{sub 2}O){sub 2}). The growth mechanism is well interpreted by a Monte Carlo simulation taking into account an accretion mechanism with hard-sphere cross section. The homogeneous nucleation mechanism has been highlighted by a direct comparison with the Classical Nucleation Theory predictions. The clusters fragmentation of ionic Na{sup +}(NaOH){sub p} et Na{sup +}(NaF){sub p} particles is studied in the second part. The way clusters fragment with size when they are excited optically is compared with theoretical previsions: this highlights the existence of an energetic barrier for special size of clusters. Finally, the fragmentation of doubly charged Na{sup +} Na{sup +} (NaOH){sub p} clusters shows a competition between the fission into two single charged fragments and the unimolecular evaporation of a neutral fragment. (author)

  18. Gas Phase Sulfur, Chlorine and Potassium Chemistry in Biomass Combustion

    DEFF Research Database (Denmark)

    Løj, Lusi Hindiyarti

    2007-01-01

    Gas Phase Sulfur, Chlorine and Alkali Metal Chemistry in Biomass Combustion Concern about aerosols formation, deposits, corrosion, and gaseous emissions during biomass combustion, especially straw, continues to be a driving force for investigation on S, Cl, K-containing species under combustions...... conditions. These trace species contained in the biomass structure will be released to the gas phase during combustion and contribute to the problems generated during the process. The investigation during this PhD project is done to stepwise improve the understanding in the chemistry and reduce...... the uncertainties. In the present work, the detailed kinetic model for gas phase sulfur, chlorine, alkali metal, and their interaction has been updated. The K/O/H/Cl chemistry, S chemistry, and their interaction can reasonably predict a range of experimental data. In general, understanding of the interaction...

  19. Phase space analysis of some interacting Chaplygin gas models

    Energy Technology Data Exchange (ETDEWEB)

    Khurshudyan, M. [Academy of Sciences of Armenia, Institute for Physical Research, Ashtarak (Armenia); Tomsk State University of Control Systems and Radioelectronics, Laboratory for Theoretical Cosmology, Tomsk (Russian Federation); Tomsk State Pedagogical University, Department of Theoretical Physics, Tomsk (Russian Federation); Myrzakulov, R. [Eurasian National University, Eurasian International Center for Theoretical Physics, Astana (Kazakhstan)

    2017-02-15

    In this paper we discuss a phase space analysis of various interacting Chaplygin gas models in general relativity. Linear and nonlinear sign changeable interactions are considered. For each case appropriate late time attractors of field equations are found. The Chaplygin gas is one of the dark fluids actively considered in modern cosmology due to the fact that it is a joint model of dark energy and dark matter. (orig.)

  20. Condensation in gas transmission pipelines. Phase behavior of mixtures of hydrogen with natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Schouten, J.A.; Michels, J.P.J. [Amsterdam Univ. (Netherlands). Van der Waals-Zeeman Inst.; Rosmalen, R.J. van [Energy, Roden (Netherlands)

    2005-05-01

    Several pressure and temperature reductions occur along gas transmission lines. Since the pressure and temperature conditions of the natural gas in the pipeline are often close to the dew point curve, liquid dropout can occur. Injection of hydrogen into the natural gas will change the phase envelope and thus the liquid dropout. This condensation of the heavy hydrocarbons requires continuous operational attention and a positive effect of hydrogen may affect the decision to introduce hydrogen. In this paper we report on calculations of the amount of condensate in a natural gas and in this natural gas mixed with 16.7% hydrogen. These calculations have been performed at conditions prevailing in gas transport lines. The results will be used to discuss the difference in liquid dropout in a natural gas and in a mixture with hydrogen at pressure reduction stations, at crossings under waterways, at side-branching, and at separators in the pipelines. (author)

  1. Gas-phase transport of fission products

    International Nuclear Information System (INIS)

    Tang, I.N.; Munkelwitz, H.R.

    1982-01-01

    The paper presents the results of an experimental investigation to show the importance of nuclear aerosol formation as a mechanism for semi-volatile fission product transport under certain postulated HTGR accident conditions. Simulated fission product Sr and Ba as oxides are impregnated in H451 graphite and released at elevated temperatures into a dry helium flow. In the presence of graphite, the oxides are quantitatively reduced to metals, which subsequently vaporize at temperatures much lower than required for the oxides alone to vaporize in the absence of graphite. A substantial fraction of the released material is associated with particulate matter, which is collected on filters located downstream at ambient temperatures. Increasing carrier-gas flow rate greatly enhances the extent of particulate transport. The release and transport of simulated fission product Ag as metal are also investigated. Electron microscopic examinations of the collected Sr and Ag aerosols show large agglomerates composed of primary particles roughly 0.06 to 0.08 μm in diameter

  2. Understanding Gas-Phase Ammonia Chemistry in Protoplanetary Disks

    Science.gov (United States)

    Chambers, Lauren; Oberg, Karin I.; Cleeves, Lauren Ilsedore

    2017-01-01

    Protoplanetary disks are dynamic regions of gas and dust around young stars, the remnants of star formation, that evolve and coagulate over millions of years in order to ultimately form planets. The chemical composition of protoplanetary disks is affected by both the chemical and physical conditions in which they develop, including the initial molecular abundances in the birth cloud, the spectrum and intensity of radiation from the host star and nearby systems, and mixing and turbulence within the disk. A more complete understanding of the chemical evolution of disks enables a more complete understanding of the chemical composition of planets that may form within them, and of their capability to support life. One element known to be essential for life on Earth is nitrogen, which often is present in the form of ammonia (NH3). Recent observations by Salinas et al. (2016) reveal a theoretical discrepancy in the gas-phase and ice-phase ammonia abundances in protoplanetary disks; while observations of comets and protostars estimate the ice-phase NH3/H2O ratio in disks to be 5%, Salinas reports a gas-phase NH3/H2O ratio of ~7-84% in the disk surrounding TW Hydra, a young nearby star. Through computational chemical modeling of the TW Hydra disk using a reaction network of over 5000 chemical reactions, I am investigating the possible sources of excess gas-phase NH3 by determining the primary reaction pathways of NH3 production; the downstream chemical effects of ionization by ultraviolet photons, X-rays, and cosmic rays; and the effects of altering the initial abundances of key molecules such as N and N2. Beyond providing a theoretical explanation for the NH3 ice/gas discrepancy, this new model may lead to fuller understanding of the gas-phase formation processes of all nitrogen hydrides (NHx), and thus fuller understanding of the nitrogen-bearing molecules that are fundamental for life as we know it.

  3. 2νββ decay of 76Ge into excited states with GERDA phase I

    Science.gov (United States)

    GERDA Collaboration; Agostini, M.; Allardt, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Barros, N.; Baudis, L.; Bauer, C.; Becerici-Schmidt, N.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Budjáš, D.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; di Vacri, A.; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Fedorova, O.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Gooch, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hegai, A.; Heisel, M.; Hemmer, S.; Heusser, G.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Janicskó Csáthy, J.; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Klimenko, A.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Medinaceli, E.; Mi, Y.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Palioselitis, D.; Panas, K.; Pandola, L.; Pelczar, K.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salathe, M.; Schmitt, C.; Schneider, B.; Schreiner, J.; Schulz, O.; Schwingenheuer, B.; Schönert, S.; Schütz, A.-K.; Selivanenko, O.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Stepaniuk, M.; Ur, C. A.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wilsenach, H.; Wojcik, M.; Yanovich, E.; Zavarise, P.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

    2015-11-01

    Two neutrino double beta decay of {}76{Ge} to excited states of {}76{Se} has been studied using data from Phase I of the GERDA experiment. An array composed of up to 14 germanium detectors including detectors that have been isotopically enriched in {}76{Ge} was deployed in liquid argon. The analysis of various possible transitions to excited final states is based on coincidence events between pairs of detectors where a de-excitation γ ray is detected in one detector and the two electrons in the other. No signal has been observed and an event counting profile likelihood analysis has been used to determine Frequentist 90% C.L. bounds for three transitions: {0}{{g}.{{s}}.}+-{2}1+: {T}1/22ν \\gt 1.6× {10}23 yr, {0}{{g}.{{s}}.}+-{0}1+: {T}1/22ν \\gt 3.7× {10}23 yr and {0}{{g}.{{s}}.}+-{2}2+: {T}1/22ν \\gt 2.3× {10}23 yr. These bounds are more than two orders of magnitude larger than those reported previously. Bayesian 90% credibility bounds were extracted and used to exclude several models for the {0}{{g}.{{s}}.}+-{0}1+ transition.

  4. Gas-phase photocatalysis in μ-reactors

    DEFF Research Database (Denmark)

    Vesborg, Peter Christian Kjærgaard; Olsen, Jakob Lind; Henriksen, Toke Riishøj

    2010-01-01

    Gas-phase photocatalysis experiments may benefit from the high sensitivity and good time response in product detection offered by μ-reactors. We demonstrate this by carrying out CO oxidation and methanol oxidation over commercial TiO2 photocatalysts in our recently developed high-sensitivity reac......Gas-phase photocatalysis experiments may benefit from the high sensitivity and good time response in product detection offered by μ-reactors. We demonstrate this by carrying out CO oxidation and methanol oxidation over commercial TiO2 photocatalysts in our recently developed high...

  5. Post-flame gas-phase sulfation of potassium chloride

    DEFF Research Database (Denmark)

    Li, Bo; Sun, Zhiwei; Li, Zhongshan

    2013-01-01

    The sulfation of KCl during biomass combustion has implications for operation and emissions: it reduces the rates of deposition and corrosion, it increases the formation of aerosols, and it leads to higher concentrations of HCl and lower concentrations of SO2 in the gas phase. Rigorously homogene......The sulfation of KCl during biomass combustion has implications for operation and emissions: it reduces the rates of deposition and corrosion, it increases the formation of aerosols, and it leads to higher concentrations of HCl and lower concentrations of SO2 in the gas phase. Rigorously...

  6. Fischer Indole Synthesis in the Gas Phase, the Solution Phase, and at the Electrospray Droplet Interface.

    Science.gov (United States)

    Bain, Ryan M; Ayrton, Stephen T; Cooks, R Graham

    2017-07-01

    Previous reports have shown that reactions occurring in the microdroplets formed during electrospray ionization can, under the right conditions, exhibit significantly greater rates than the corresponding bulk solution-phase reactions. The observed acceleration under electrospray ionization could result from a solution-phase, a gas-phase, or an interfacial reaction. This study shows that a gas-phase ion/molecule (or ion/ion) reaction is not responsible for the observed rate enhancement in the particular case of the Fischer indole synthesis. The results show that the accelerated reaction proceeds in the microdroplets, and evidence is provided that an interfacial process is involved. Graphical Abstract GRAPHICAL ABSTRACT TEXT HERE] -->.

  7. Analytical study of solids-gas two phase flow

    International Nuclear Information System (INIS)

    Hosaka, Minoru

    1977-01-01

    Fundamental studies were made on the hydrodynamics of solids-gas two-phase suspension flow, in which very small solid particles are mixed in a gas flow to enhance the heat transfer characteristics of gas cooled high temperature reactors. Especially, the pressure drop due to friction and the density distribution of solid particles are theoretically analyzed. The friction pressure drop of two-phase flow was analyzed based on the analytical result of the single-phase friction pressure drop. The calculated values of solid/gas friction factor as a function of solid/gas mass loading are compared with experimental results. Comparisons are made for Various combinations of Reynolds number and particle size. As for the particle density distribution, some factors affecting the non-uniformity of distribution were considered. The minimum of energy dispersion was obtained with the variational principle. The suspension density of particles was obtained as a function of relative distance from wall and was compared with experimental results. It is concluded that the distribution is much affected by the particle size and that the smaller particles are apt to gather near the wall. (Aoki, K.)

  8. Gas-phase mechanisms in the growth of ZrCyN1-y thin films by pulsed reactive crossed-beam laser ablation

    International Nuclear Information System (INIS)

    Spillmann, H.; Clerc, C.; Doebeli, M.; Willmott, P.R.

    2002-01-01

    Superhard zirconium carbonitride films have been grown via pulsed reactive crossed-beam laser ablation (PRCLA) using zirconium metal and a nitrogen- and carbon-containing gas pulse mixture. The control of stoichiometry was much simplified by using the thermally stable gas-phase species N 2 and CH 4 . The gas-phase processes are investigated using quadrupole mass spectroscopy and optical emission spectroscopy. The excitation of the ablation plume depends intimately on the collision partner of the gas pulse, in particular on its density of states and the probability of energy transfer to internal degrees of freedom

  9. Electronically excited and ionized states in condensed phase: Theory and applications

    Science.gov (United States)

    Sadybekov, Arman

    Predictive modeling of chemical processes in silico is a goal of XXI century. While robust and accurate methods exist for ground-state properties, reliable methods for excited states are still lacking and require further development. Electronically exited states are formed by interactions of matter with light and are responsible for key processes in solar energy harvesting, vision, artificial sensors, and photovoltaic applications. The greatest challenge to overcome on our way to a quantitative description of light-induced processes is accurate inclusion of the effect of the environment on excited states. All above mentioned processes occur in solution or solid state. Yet, there are few methodologies to study excited states in condensed phase. Application of highly accurate and robust methods, such as equation-of-motion coupled-cluster theory EOM-CC, is limited by a high computational cost and scaling precluding full quantum mechanical treatment of the entire system. In this thesis we present successful application of the EOM-CC family of methods to studies of excited states in liquid phase and build hierarchy of models for inclusion of the solvent effects. In the first part of the thesis we show that a simple gasphase model is sufficient to quantitatively analyze excited states in liquid benzene, while the latter part emphasizes the importance of explicit treatment of the solvent molecules in the case of glycine in water solution. In chapter 2, we use a simple dimer model to describe exciton formation in liquid and solid benzene. We show that sampling of dimer structures extracted from the liquid benzene is sufficient to correctly predict exited-state properties of the liquid. Our calculations explain experimentally observed features, which helped to understand the mechanism of the excimer formation in liquid benzene. Furthermore, we shed light on the difference between dimer configurations in the first solvation shell of liquid benzene and in unit cell of solid

  10. SVOC partitioning between the gas phase and settled dust indoors

    DEFF Research Database (Denmark)

    Weschler, Charles J.; Nazaroff, W. W.

    2010-01-01

    Semivolatile organic compounds (SVOCs) are a major class of indoor pollutants. Understanding SVOC partitioning between the gas phase and settled dust is important for characterizing the fate of these species indoors and the pathways by which humans are exposed to them. Such knowledge also helps...

  11. Gas-Phase IR Spectroscopy of Deprotonated Amino Acids

    NARCIS (Netherlands)

    Oomens, J.; Steill, J. D.; Redlich, B.

    2009-01-01

    Gas-phase infrared multiple photon dissociation (IRMPD) spectra have been recorded for the conjugate bases of a series of amino acids (Asp, Cys, Glu, Phe, Set, Trp, Tyr). The spectra are dominated by strong symmetric and antisymmetric carboxylate stretching modes around 1300 and 1600 cm(-1),

  12. Gas phase toluene isopropylation over high silica mordenite

    Indian Academy of Sciences (India)

    Mordenite (HM) catalysts with three different Si/Al ratios were compared for their activity and selectivities in gas phase toluene isopropylation with isopropanol. Catalyst with Si/Al ratio 44.9 offered better cumene selectivity, hence, it was chosen for detailed kinetic investigations. The influence of various process parameters ...

  13. Diamond-like-carbon nanoparticle production and agglomeration following UV multi-photon excitation of static naphthalene/helium gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, A. J.; Ruth, A. A., E-mail: a.ruth@ucc.ie [Physics Department and Environmental Research Institute, University College Cork, Cork (Ireland); Tielens, A. G. G. M. [Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333-CA Leiden (Netherlands)

    2016-07-14

    We report the formation of nanoparticles with significant diamond character after UV multi-photon laser excitation of gaseous naphthalene, buffered in static helium gas, at room temperature. The nanoparticles are identified in situ by their absorption and scattering spectra between 400 and 850 nm, which are modeled using Mie theory. Comparisons of the particles’ spectroscopic and optical properties with those of carbonaceous materials indicate a sp{sup 3}/sp{sup 2} hybridization ratio of 8:1 of the particles formed. The particle extinction in the closed static (unstirred) gas-phase system exhibits a complex and quasi-oscillatory time dependence for the duration of up to several hours with periods ranging from seconds to many minutes. The extinction dynamics of the system is based on a combination of transport features and particle interaction, predominantly agglomeration. The relatively long period of agglomeration allows for a unique analysis of the agglomeration process of diamond-like carbon nanoparticles in situ.

  14. Reactions of newly formed fission products in the gas phase

    International Nuclear Information System (INIS)

    Strickert, R.G.

    1976-01-01

    A dynamic gas-flow system was constructed which stopped fission products in the gas phase and rapidly separated (in less than 2 sec) volatile compounds from non-volatile ones. The filter assembly designed and used was shown to stop essentially all non-volatile fission products. Between 5 percent and 20 percent of tellurium fission-product isotopes reacted with several hydrocarbon gases to form volatile compounds, which passed through the filter. With carbon monoxide gas, volatile tellurium compound(s) (probably TeCO) were also formed with similar efficiencies. The upper limits for the yields of volatile compounds formed between CO and tin and antimony fission products were shown to be less than 0.3 percent, so tellurium nuclides, not their precursors, reacted with CO. It was found that CO reacted preferentially with independently produced tellurium atoms; the reaction efficiency of beta-produced atoms was only 27 +- 3 percent of that of the independently formed atoms. The selectivity, which was independent of the over-all reaction efficiency, was shown to be due to reaction of independently formed atoms in the gas phase. The gas phase reactions are believed to occur mainly at thermal energies because of the independence of the yield upon argon moderator mole-fraction (up to 80 percent). It was shown in some experiments that about one-half of the TeCO decomposed in passing through a filter and that an appreciable fraction (approximately 20 percent) of the tellurium atoms deposited on the filter reacted agin with CO. Other tellurium atoms on the filter surface (those formed by beta decay and those formed independently but not reacting in the gas phase) also reacted with CO, but probably somewhat less efficiently than atoms formed by TeCO decomposition. No evidence was found for formation of TeCO as a direct result of beta-decay

  15. Highly Selective Continuous Gas-Phase Methoxycarbonylation of Ethylene with Supported Ionic Liquid Phase (SILP) Catalysts

    DEFF Research Database (Denmark)

    Khokarale, Santosh Govind; Garcia Suárez, Eduardo José; Fehrmann, Rasmus

    2017-01-01

    Supported ionic liquid phase (SILP) technology was applied for the first time to the Pd-catalyzed continuous, gas-phase methoxycarbonylation of ethylene to selectively produce methyl propanoate (MP) in high yields. The influence of catalyst and reaction parameters such as, for example, ionic liquid...

  16. Continuous gas-phase hydroformylation of 1-butene using supported ionic liquid phase (SILP) catalysts

    DEFF Research Database (Denmark)

    Haumann, Marco; Dentler, Katharina; Joni, Joni

    2007-01-01

    The concept of supported ionic liquid phase (SILP) catalysis has been extended to 1-butene hydroformylation. A rhodium-sulfoxantphos complex was dissolved in [BMIM][n-C8H17OSO3] and this solution was highly dispersed on silica. Continuous gas-phase experiments in a fixed-bed reactor revealed...

  17. Direct method gas-phase oxygen abundances of four Lyman break analogs

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Jonathan S.; Croxall, Kevin V.; Pogge, Richard W. [Department of Astronomy, The Ohio State University, Columbus, OH 43201 (United States)

    2014-09-10

    We measure the gas-phase oxygen abundances in four Lyman break analogs using auroral emission lines to derive direct abundances. The direct method oxygen abundances of these objects are generally consistent with the empirically derived strong-line method values, confirming that these objects are low oxygen abundance outliers from the mass-metallicity (MZ) relation defined by star forming Sloan Digital Sky Survey galaxies. We find slightly anomalous excitation conditions (Wolf-Rayet features) that could potentially bias the empirical estimates toward high values if caution is not exercised in the selection of the strong-line calibration. The high rate of star formation and low oxygen abundance of these objects is consistent with the predictions of the fundamental metallicity relation, in which the infall of relatively unenriched gas simultaneously triggers an episode of star formation and dilutes the interstellar medium of the host galaxy.

  18. Systematic Search for Chemical Reactions in Gas Phase Contributing to Methanol Formation in Interstellar Space.

    Science.gov (United States)

    Gamez-Garcia, Victoria G; Galano, Annia

    2017-10-05

    A massive search for chemical routes leading to methanol formation in gas phase has been conducted using computational chemistry, at the CBS-QB3 level of theory. The calculations were performed at five different temperatures (100, 80, 50, 20, and 10 K) and at three pressures (0.1, 0.01, and 0.001 atm) for each temperature. The search was focused on identifying reactions with the necessary features to be viable in the interstellar medium (ISM). A searching strategy was applied to that purpose, which allowed to reduce an initial set of 678 possible reactions to a subset of 11 chemical routes that are recommended, for the first time, as potential candidates for contributing to methanol formation in the gas phase of the ISM. They are all barrier-less, and thus they are expected to take place at collision rates. Hopefully, including these reactions in the currently available models, for the gas-phase methanol formation in the ISM, would help improving the predicted fractional abundance of this molecule in dark clouds. Further investigations, especially those dealing with grain chemistry and electronic excited states, would be crucial to get a complete picture of the methanol formation in the ISM.

  19. SILP catalysis in gas-phase hydroformylation and carbonylation

    Energy Technology Data Exchange (ETDEWEB)

    Riisager, A.; Fehrmann, R. [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Chemistry; Haumann, M.; Wasserscheid, P. [Univ. Erlangen-Nuernberg (Germany). Lehrstuhl fuer Chemische Reaktionstechnik

    2006-07-01

    Supported ionic liquid phase (SILP) catalysts are new materials consisting of an ionic liquid-metal catalyst solution highly dispersed on a porous support. The use of a non-volatile, ionic liquid catalyst phase in SILP catalysts results in a stable heterogeneous-type material with selectivity and efficiency like homogeneous catalysts. The silica-supported SILP Rh-bisphosphine hydroformylation catalyst exhibited good activities and excellent selectivities in gas phase hydroformylation with stability exceeding 700 hours time-on-stream. Spectroscopic and kinetic data confirmed the homogeneous nature of the catalyst. In the Rh- SILP catalysed carbonylation of methanol the formation of undesired by-products could be suppressed by variation of residence time and gas pressure. (orig.)

  20. Zpif's law in the liquid gas phase transition of nuclei

    International Nuclear Information System (INIS)

    Ma, Y.G.

    1999-01-01

    Zpif's law in the field of linguistics is tested in the nuclear disassembly within the framework of isospin dependent lattice gas model. It is found that the average cluster charge (or mass) of rank n in the charge (or mass) list shows exactly inversely to its rank, i.e., there exists Zpif's law, at the phase transition temperature. This novel criterion shall be helpful to search the nuclear liquid gas phase transition experimentally and theoretically. In addition, the finite size scaling of the effective phase transition temperature at which the Zpif's law appears is studied for several systems with different mass and the critical exponents of ν and β are tentatively extracted. (orig.)

  1. Surface chemical reactions induced by molecules electronically-excited in the gas

    DEFF Research Database (Denmark)

    Petrunin, Victor V.

    2011-01-01

    and alignment are taking place, guiding all the molecules towards the intersections with the ground state PES, where transitions to the ground state PES will occur with minimum energy dissipation. The accumulated kinetic energy may be used to overcome the chemical reaction barrier. While recombination chemical...... be readily produced. Products of chemical adsorption and/or chemical reactions induced within adsorbates are aggregated on the surface and observed by light scattering. We will demonstrate how pressure and spectral dependencies of the chemical outcomes, polarization of the light and interference of two laser...... beams inducing the reaction can be used to distinguish the new process we try to investigate from chemical reactions induced by photoexcitation within adsorbed molecules and/or gas phase photolysis....

  2. Gas phase decontamination of gaseous diffusion process equipment

    International Nuclear Information System (INIS)

    Bundy, R.D.; Munday, E.B.; Simmons, D.W.; Neiswander, D.W.

    1994-01-01

    D ampersand D of the process facilities at the gaseous diffusion plants (GDPs) will be an enormous task. The EBASCO estimate places the cost of D ampersand D of the GDP at the K-25 Site at approximately $7.5 billion. Of this sum, nearly $4 billion is associated with the construction and operation of decontamination facilities and the dismantlement and transport of contaminated process equipment to these facilities. In situ long-term low-temperature (LTLT) gas phase decontamination is being developed and demonstrated at the K-25 site as a technology that has the potential to substantially lower these costs while reducing criticality and safeguards concerns and worker exposure to hazardous and radioactive materials. The objective of gas phase decontamination is to employ a gaseous reagent to fluorinate nonvolatile uranium deposits to form volatile LJF6, which can be recovered by chemical trapping or freezing. The LTLT process permits the decontamination of the inside of gas-tight GDP process equipment at room temperature by substituting a long exposure to subatmospheric C1F for higher reaction rates at higher temperatures. This paper outlines the concept for applying LTLT gas phase decontamination, reports encouraging laboratory experiments, and presents the status of the design of a prototype mobile system. Plans for demonstrating the LTLT process on full-size gaseous diffusion equipment are also outlined briefly

  3. Dynamic modulation of corticospinal excitability and short-latency afferent inhibition during onset and maintenance phase of selective finger movement.

    Science.gov (United States)

    Cho, Hyun Joo; Panyakaew, Pattamon; Thirugnanasambandam, Nivethida; Wu, Tianxia; Hallett, Mark

    2016-06-01

    During highly selective finger movement, corticospinal excitability is reduced in surrounding muscles at the onset of movement but this phenomenon has not been demonstrated during maintenance of movement. Sensorimotor integration may play an important role in selective movement. We sought to investigate how corticospinal excitability and short-latency afferent inhibition changes in active and surrounding muscles during onset and maintenance of selective finger movement. Using transcranial magnetic stimulation (TMS) and paired peripheral stimulation, input-output recruitment curve and short-latency afferent inhibition (SAI) were measured in the first dorsal interosseus and abductor digiti minimi muscles during selective index finger flexion. Motor surround inhibition was present only at the onset phase, but not at the maintenance phase of movement. SAI was reduced at onset but not at the maintenance phase of movement in both active and surrounding muscles. Our study showed dynamic changes in corticospinal excitability and sensorimotor modulation for active and surrounding muscles in different movement states. SAI does not appear to contribute to motor surround inhibition at the movement onset phase. Also, there seems to be different inhibitory circuit(s) other than SAI for the movement maintenance phase in order to delineate the motor output selectively when corticospinal excitability is increased in both active and surrounding muscles. This study enhances our knowledge of dynamic changes in corticospinal excitability and sensorimotor interaction in different movement states to understand normal and disordered movements. Published by Elsevier Ireland Ltd.

  4. Collective nuclear excitations with Skyrme-second random-phase approximation

    International Nuclear Information System (INIS)

    Gambacurta, D.; Catara, F.; Grasso, M.

    2010-01-01

    Second random-phase approximation (RPA) calculations with a Skyrme force are performed to describe both high- and low-lying excited states in 16 O. The coupling between one particle-one hole and two particle-two hole as well as that between two particle-two hole configurations among themselves are fully taken into account, and the residual interaction is never neglected; we do not resort therefore to a generally used approximate scheme where only the first kind of coupling is considered. The issue of the rearrangement terms in the matrix elements beyond the standard RPA will be considered in detail in a forthcoming paper. Two approximations are employed here for these rearrangement terms: they are either neglected or evaluated with the RPA procedure. As a general feature of second RPA results, a several-MeV shift of the strength distribution to lower energies is systematically found with respect to RPA distributions. A much more important fragmentation of the strength is also naturally provided by the second RPA owing to the huge number of two particle-two hole configurations. A better description of the excitation energies of the low-lying 0 + and 2 + states is obtained with the second RPA than with the RPA.

  5. Preconceptual design of the gas-phase decontamination demonstration cart

    International Nuclear Information System (INIS)

    Munday, E.B.

    1993-12-01

    Removal of uranium deposits from the interior surfaces of gaseous diffusion equipment will be a major portion of the overall multibillion dollar effort to decontaminate and decommission the gaseous diffusion plants. Long-term low-temperature (LTLT) gas-phase decontamination is being developed at the K-25 Site as an in situ decontamination process that is expected to significantly lower the decontamination costs, reduce worker exposure to radioactive materials, and reduce safeguard concerns. This report documents the preconceptual design of the process equipment that is necessary to conduct a full-scale demonstration of the LTLT method in accordance with the process steps listed above. The process equipment and method proposed in this report are not intended to represent a full-scale production campaign design and operation, since the gas evacuation, gas charging, and off-gas handling systems that would be cost effective in a production campaign are not cost effective for a first-time demonstration. However, the design presented here is expected to be applicable to special decontamination projects beyond the demonstration, which could include the Deposit Recovery Program. The equipment will therefore be sized to a 200 ft size 1 converter (plus a substantial conservative design margin), which is the largest item of interest for gas phase decontamination in the Deposit Recovery Program. The decontamination equipment will allow recovery of the UF 6 , which is generated from the reaction of ClF 3 with the uranium deposits, by use of NaF traps

  6. Gas-liquid two-phase flows in double inlet cyclones for natural gas separation

    DEFF Research Database (Denmark)

    Yang, Yan; Wang, Shuli; Wen, Chuang

    2017-01-01

    The gas-liquid two-phase flow within a double inlet cyclone for natural gasseparation was numerically simulated using the discrete phase model. The numericalapproach was validated with the experimental data, and the comparison resultsagreed well with each other. The simulation results showed...... that the strong swirlingflow produced a high centrifugal force to remove the particles from the gas mixture.The larger particles moved downward on the internal surface and were removeddue to the outer vortex near the wall. Most of the tiny particles went into the innervortex zones and escaped from the up...

  7. Sub-nanometre resolution of atomic motion during electronic excitation in phase-change materials.

    Science.gov (United States)

    Mitrofanov, Kirill V; Fons, Paul; Makino, Kotaro; Terashima, Ryo; Shimada, Toru; Kolobov, Alexander V; Tominaga, Junji; Bragaglia, Valeria; Giussani, Alessandro; Calarco, Raffaella; Riechert, Henning; Sato, Takahiro; Katayama, Tetsuo; Ogawa, Kanade; Togashi, Tadashi; Yabashi, Makina; Wall, Simon; Brewe, Dale; Hase, Muneaki

    2016-02-12

    Phase-change materials based on Ge-Sb-Te alloys are widely used in industrial applications such as nonvolatile memories, but reaction pathways for crystalline-to-amorphous phase-change on picosecond timescales remain unknown. Femtosecond laser excitation and an ultrashort x-ray probe is used to show the temporal separation of electronic and thermal effects in a long-lived (>100 ps) transient metastable state of Ge2Sb2Te5 with muted interatomic interaction induced by a weakening of resonant bonding. Due to a specific electronic state, the lattice undergoes a reversible nondestructive modification over a nanoscale region, remaining cold for 4 ps. An independent time-resolved x-ray absorption fine structure experiment confirms the existence of an intermediate state with disordered bonds. This newly unveiled effect allows the utilization of non-thermal ultra-fast pathways enabling artificial manipulation of the switching process, ultimately leading to a redefined speed limit, and improved energy efficiency and reliability of phase-change memory technologies.

  8. Collective excitations in the Penson-Kolb model: A generalized random-phase-approximation study

    International Nuclear Information System (INIS)

    Roy, G.K.; Bhattacharyya, B.

    1997-01-01

    The evolution of the superconducting ground state of the half-filled Penson-Kolb model is examined as a function of the coupling constant using a mean-field approach and the generalized random phase approximation (RPA) in two and three dimensions. On-site singlet pairs hop to compete against single-particle motion in this model, giving the coupling constant a strong momentum dependence. There is a pronounced bandwidth enhancement effect that converges smoothly to a finite value in the strong-coupling (Bose) regime. The low-lying collective excitations evaluated in generalized RPA show a linear dispersion and a gradual crossover from the weak-coupling (BCS) limit to the Bose regime; the mode velocity increases monotonically in sharp contrast to the attractive Hubbard model. Analytical results are derived in the asymptotic limits. copyright 1997 The American Physical Society

  9. Characterization of Isomeric Glycans by Reversed Phase Liquid Chromatography-Electronic Excitation Dissociation Tandem Mass Spectrometry

    Science.gov (United States)

    Tang, Yang; Wei, Juan; Costello, Catherine E.; Lin, Cheng

    2018-04-01

    The occurrence of numerous structural isomers in glycans from biological sources presents a severe challenge for structural glycomics. The subtle differences among isomeric structures demand analytical methods that can provide structural details while working efficiently with on-line glycan separation methods. Although liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful tool for mixture analysis, the commonly utilized collision-induced dissociation (CID) method often does not generate a sufficient number of fragments at the MS2 level for comprehensive structural characterization. Here, we studied the electronic excitation dissociation (EED) behaviors of metal-adducted, permethylated glycans, and identified key spectral features that could facilitate both topology and linkage determinations. We developed an EED-based, nanoscale, reversed phase (RP)LC-MS/MS platform, and demonstrated its ability to achieve complete structural elucidation of up to five structural isomers in a single LC-MS/MS analysis. [Figure not available: see fulltext.

  10. Beyond the random-phase approximation for the electron correlation energy: the importance of single excitations.

    Science.gov (United States)

    Ren, Xinguo; Tkatchenko, Alexandre; Rinke, Patrick; Scheffler, Matthias

    2011-04-15

    The random-phase approximation (RPA) for the electron correlation energy, combined with the exact-exchange (EX) energy, represents the state-of-the-art exchange-correlation functional within density-functional theory. However, the standard RPA practice--evaluating both the EX and the RPA correlation energies using Kohn-Sham (KS) orbitals from local or semilocal exchange-correlation functionals--leads to a systematic underbinding of molecules and solids. Here we demonstrate that this behavior can be corrected by adding a "single excitation" contribution, so far not included in the standard RPA scheme. A similar improvement can also be achieved by replacing the non-self-consistent EX total energy by the corresponding self-consistent Hartree-Fock total energy, while retaining the RPA correlation energy evaluated using KS orbitals. Both schemes achieve chemical accuracy for a standard benchmark set of noncovalent intermolecular interactions.

  11. Angular intensity of a gas-phase field ionization source

    International Nuclear Information System (INIS)

    Orloff, J.; Swanson, L.W.

    1979-01-01

    Angular intensities of 1 μA sr -1 have been measured for a gas-phase field ionization source in an optical column under practical operating conditions. The source, which was differentially pumped and cooled to 77 K, utilized a -oriented iridium emitter and precooled hydrogen gas at 10 -2 Torr. The ion beam was collimated with an electrostatic lens and detected below an aperture subtending 0.164 msr. A transmitted current of approx.10 -10 A was measured at voltages corresponding to a field of approx. =2.2 V/A at the emitter

  12. Photoisomerization action spectroscopy of the carbocyanine dye DTC+ in the gas phase.

    Science.gov (United States)

    Adamson, Brian D; Coughlan, Neville J A; da Silva, Gabriel; Bieske, Evan J

    2013-12-19

    Molecular photoisomerization plays a crucial role in diverse biological and technological contexts. Here, we combine ion mobility spectrometry and laser spectroscopy to characterize the photoisomerization of molecular cations in the gas phase. The target molecular ions, polymethine dye cations 3,3'-diethylthiacarbocyanine (DTC(+)), are propelled through helium buffer gas by an electric field and are photoisomerized by light from a tunable laser. Photoexcitation over the 450-570 nm range converts trans-DTC(+) to cis-DTC(+), noticeably modifying the ions' arrival time distribution. The photoisomerization action spectrum, which has a maximum at 535 nm, resembles the absorption spectrum of DTC(+) in solution but is shifted 25 nm to shorter wavelength. Comparisons between measured and calculated mobilities suggest that the photoisomer involves a twist about the second C-C bond in the methine chain (8,9-cis isomer) rather than a twist about the first methine C-C bond (2,8-cis isomer). It is postulated that the excited gas-phase ions internally convert from the S1 Franck-Condon region to the S0 manifold and explore the conformational landscape as they cool through He buffer gas collisions. Master equation simulations of the relaxation process in the S0 manifold suggest that the 8,9-cis isomer is preferred over the 2,8-cis isomer because it lies lower in energy and because it is separated from the trans isomer by a substantially higher barrier. The study demonstrates that the photoisomerization of molecular ions can be probed selectively in the gas phase, providing insights into photoisomerization mechanisms and information on the solvent-free absorption spectrum.

  13. Noncovalent Halogen Bonding as a Mechanism for Gas-Phase Clustering

    DEFF Research Database (Denmark)

    Wegeberg, Christina; Donald, William A.; McKenzie, Christine

    2017-01-01

    in the crystalline phases of PhIO2 and its derivatives serve as models for the structures of larger gas-phase clusters, and calculations on simple model gas-phase dimer and trimer clusters result in similar motifs. This is the first account of halogen bonding playing an extensive role in gas-phase associations....

  14. Collective excitations in semiconductor superlattices and plasma modes of a two-dimensional electron gas with spatially modulated charge density

    International Nuclear Information System (INIS)

    Eliasson, G.L.

    1987-01-01

    The theory of collective excitations in semiconductor superlattices is formulated by using linear response theory. Different kinds of collective excitations in type I (GaAs-GaAlAs) and type II (GaSb-InAs) superlattices are surveyed. Special attention is paid to the presence of surface and finite-size effects. In calculating the dielectric matrix, the effect of different approximations of the system is discussed. The theory for inelastic length scattering (Raman scattering), and for Electron Energy Loss (EEL) due to collective excitations, is formulated. Calculations for several model systems are presented and the main features of the spectra are discussed. In part II the theory of collective excitations of a two-dimensional electron gas with a spatially periodic equilibrium density is formulated. As a first example a periodic array of two-dimensional electron gas strips with constant equilibrium density is studied. The integral equation that describes the charge fluctuations on the strips is derived and solved numerically. The spatial dependence of the density fluctuation across a single strip can be in the form of either propagating or evanescent waves

  15. Industrial aspects of gas-liquid two-phase flow

    International Nuclear Information System (INIS)

    Hewitt, G.F.

    1977-01-01

    The lecture begins by reviewing the various types of plant in which two phase flow occurs. Specifically, boiling plant, condensing plant and pipelines are reviewed, and the various two phase flow problems occurring in them are described. Of course, many other kinds of chemical engineering plant involve two phase flow, but are somewhat outside the scope of this lecture. This would include distillation columns, vapor-liquid separators, absorption towers etc. Other areas of industrial two phase flow which have been omitted for space reasons from this lecture are those concerned with gas/solids, liquid/solid and liquid/liquid flows. There then follows a description of some of the two phase flow processes which are relevant in industrial equipment and where special problems occur. The topics chosen are as follows: (1) pressure drop; (2) horizontal tubes - separation effects non-uniformites in heat transfer coefficient, effect of bends on dryout; (3) multicomponent mixtures - effects in pool boiling, mass transfer effects in condensation and Marangoni effects; (4) flow distribution - manifold problems in single phase flow, separation effects at a single T-junction in two phase flow and distribution in manifolds in two phase flow; (5) instability - oscillatory instability, special forms of instability in cryogenic systems; (6) nucleate boiling - effect of variability of surface, unresolved problems in forced convective nucleate boiling; and (7) shell side flows - flow patterns, cross flow boiling, condensation in cross flow

  16. Preconcentration in gas or liquid phases using adsorbent thin films

    Directory of Open Access Journals (Sweden)

    Antonio Pereira Nascimento Filho

    2006-03-01

    Full Text Available The possibility of preconcentration on microchannels for organic compounds in gas or liquid phases was evaluated. Microstructures with different geometries were mechanically machined using poly(methyl methacrylate - PMMA as substrates and some cavities were covered with cellulose. The surfaces of the microchannels were modified by plasma deposition of hydrophilic or hydrophobic films using 2-propanol and hexamethyldisilazane (HMDS, respectively. Double layers of HMDS + 2-propanol were also used. Adsorption characterization was made by Quartz Crystal Measurements (QCM technique using reactants in a large polarity range that showed the adsorption ability of the structures depends more on the films used than on the capillary phenomena. Cellulose modified by double layer film showed a high retention capacity for all gaseous compounds tested. However, structures without plasma deposition showed low retention capacity. Microchannels modified with double layers or 2-propanol plasma films showed higher retention than non-modified ones on gas or liquid phase.

  17. Long-lived gas-phase radicals from combustion

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, Takashi; Furusawa, Koji; Amano, Toshiji; Okubo, Yoichi; Tsuchiya, Jun' ichi; Yoshizawa, Fujiroku; Akutsu, Yoshiaki; Tamura, Masamitsu; Yoshida, Tadao (Univ. of Tokyo (Japan))

    1989-04-20

    On indoor air pollution or fire, it is feared that the gas-phase radicals from the combustion of inflammables or fuel seriously exert an influence on the organisms as harmful matter. The gas-phase radicals were studied using the electron spin resonance (ESR) spin-trapping technique. For the spin trap solution, 0.1 mol solution of {alpha}-phenyl-N-t-butylnitron in benzene was used. As a result, apparently long-lived and highly reactive oxygen-centered radicals were detected in the smoke from polyethylene, polypropylene, polystyrene, polymethylmethacrylate, cellulose, kerosene, benzene, acetone, methanol and butylalcohol. It is suggested that the production mechanism for the radicals should be different from olefin-NOx-air system reaction, which is considered for the radicals from cigarette smoke. 11 refs., 6 figs., 2 tabs.

  18. Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy

    Science.gov (United States)

    Zhu, Yi; Cai, Zhonghou; Chen, Pice; Zhang, Qingteng; Highland, Matthew J.; Jung, Il Woong; Walko, Donald A.; Dufresne, Eric M.; Jeong, Jaewoo; Samant, Mahesh G.; Parkin, Stuart S. P.; Freeland, John W.; Evans, Paul G.; Wen, Haidan

    2016-02-01

    Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase separated regions. The ability to simultaneously track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of-the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation is initiated at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, and is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO2. The direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems.

  19. Gas phase fractionation method using porous ceramic membrane

    Science.gov (United States)

    Peterson, Reid A.; Hill, Jr., Charles G.; Anderson, Marc A.

    1996-01-01

    Flaw-free porous ceramic membranes fabricated from metal sols and coated onto a porous support are advantageously used in gas phase fractionation methods. Mean pore diameters of less than 40 .ANG., preferably 5-20 .ANG. and most preferably about 15 .ANG., are permeable at lower pressures than existing membranes. Condensation of gases in small pores and non-Knudsen membrane transport mechanisms are employed to facilitate and increase membrane permeability and permselectivity.

  20. 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

  1. The gas chimney formation during the steam explosion premixing phase

    International Nuclear Information System (INIS)

    Leskovar, M.

    2001-01-01

    The crucial part in isothermal premixing experiment simulation is the correct prediction of the gas chimney, which forms when the spheres penetrate into water. The first simulation results with the developed original combined multiphase model showed that the gas chimney starts to close at the wrong place at the top of the chimney and not in the middle, like it was observed in the experiments. To find the physical explanation for this identified weakness of our numerical model a comprehensive parametric analysis (mesh size, initial water-air surface thickness, water density, momentum coupling starting position) has been performed. It was established that the reason for the unphysical gas chimney closing at the top could be the gradual air-water density transition in the experiment model, since there is due to the finite differences description always a transition layer with intermediate phases density over the pure water phase. It was shown that this difference between our numerical model and the experiment can be somewhat compensated if the spheres interfacial drag coefficient at the upmost mesh plane of the unphysical air-water transition layer is artificially risen. On this way a more correct gas chimney formation can be obtained.(author)

  2. The Influence of Mixing in High Temperature Gas Phase Reactions

    DEFF Research Database (Denmark)

    Østberg, Martin

    1996-01-01

    by injection of NH3 with carrier gas into the flue gas. NH3 can react with NO and form N2, but a competing reaction path is the oxidation of NH3 to NO.The SNR process is briefly described and it is shown by chemical kinetic modelling that OH radicals under the present conditions will initiate the reaction......The objective of this thesis is to describe the mixing in high temperature gas phase reactions.The Selective Non-Catalytic Reduction of NOx (referred as the SNR process) using NH3 as reductant was chosen as reaction system. This in-furnace denitrification process is made at around 1200 - 1300 K...... diffusion. The SNR process is simulated using the mixing model and an empirical kinetic model based on laboratory experiments.A bench scale reactor set-up has been built using a natural gas burner to provide the main reaction gas. The set-up has been used to perform an experimental investigation...

  3. Application of radionuclide ventriculography phase analysis in patients with atrial or ventricular pacing for detecting ventricular abnormal excitation

    International Nuclear Information System (INIS)

    Shi Rongfang; Wang Zhonggan; Li Shengting

    1996-01-01

    The aim of the study was to increase the accuracy of detecting ventricular abnormal excitation. During atrial or ventricular pacing, radionuclide ventriculography phase analysis (RNV-PA) was performed in 17 patients with Wolff-Parkinson-White (W-P-W) syndrome and paroxysmal supra ventricular tachycardia (PSVT) and ventricular tachycardia (PVT). During pacing, detection rate of abnormal excitation by RNV-PA was 95.5%, compared with 68.2% during basic conduction. Atrial or ventricular pacing can significantly increase the detection rate of abnormal excitation by RNV-PA in patients with W-P-W syndrome. It may be a valuable method for identifying the abnormal excitation and estimating the therapeutic effect of ablation

  4. GAS PHASE SELECTIVE PHOTOXIDATION OF ALCOHOLS USING LIGHT-ACTIVATED TITANIUM DIOXIDE AND MOLECULAR OXYGEN

    Science.gov (United States)

    Gas Phase Selective Oxidation of Alcohols Using Light-Activated Titanium Dioxide and Molecular Oxygen Gas phase selective oxidations of various primary and secondary alcohols are studied in an indigenously built stainless steel up-flow photochemical reactor using ultravi...

  5. Two-Phase Phenomena In Wet Flue Gas Desulfurization Process

    International Nuclear Information System (INIS)

    Minzer, U.; Moses, E.J.; Toren, M.; Blumenfeld, Y.

    1998-01-01

    In order to reduce sulfur oxides discharge, Israel Electric Corporation (IEC) is building a wet Flue Gas Desulfurization (FGD) facility at Rutenberg B power station. The primary objective of IEC is to minimize the occurrence of stack liquid discharge and avoid the discharge of large droplets, in order to prevent acid rain around the stack. Liquid discharge from the stack is the integrated outcome of two-phase processes, which are discussed in this work. In order to estimate droplets discharge the present investigation employs analytical models, empirical tests, and numerical calculations of two-phase phenomena. The two-phase phenomena are coupled and therefore cannot be investigated separately. The present work concerns the application of Computational Fluid Dynamic (CFD) as an engineering complementary tool in the IEC investigation

  6. FLUIDDYNAMIC ASPECTS OF GAS-PHASE ETHYLENE POLYMERIZATION REACTOR DESIGN

    Directory of Open Access Journals (Sweden)

    Guardani R.

    1998-01-01

    Full Text Available The relative importance of design variables affecting the fluiddynamic behavior of a fluidized bed reactor for the gas-phase ethylene polymerization is discussed, based on mathematical modeling. The three-phase bubbling fluidized bed model is based on axially distributed properties for the bubble, cloud and emulsion phases, combined with correlations for population balance and entrainment. Under the operating conditions adopted in most industrial processes, the reactor performance is affected mainly by the reaction rate and solids entrainment. Simulation results indicate that an adequate design of the freeboard and particle collecting equipment is of primary importance in order to produce polymeric particles with the desired size distribution, as well as to keep entrainment and catalyst feed rates at adequate levels.

  7. Fundamental thermochemical properties of amino acids: gas-phase and aqueous acidities and gas-phase heats of formation.

    Science.gov (United States)

    Stover, Michele L; Jackson, Virgil E; Matus, Myrna H; Adams, Margaret A; Cassady, Carolyn J; Dixon, David A

    2012-03-08

    The gas-phase acidities of the 20 L-amino acids have been predicted at the composite G3(MP2) level. A broad range of structures of the neutral and anion were studied to determine the lowest energy conformer. Excellent agreement is found with the available experimental gas-phase deprotonation enthalpies, and the calculated values are within experimental error. We predict that tyrosine is deprotonated at the CO(2)H site. Cysteine is predicted to be deprotonated at the SH but the proton on the CO(2)H is shared with the S(-) site. Self-consistent reaction field (SCRF) calculations with the COSMO parametrization were used to predict the pK(a)'s of the non-zwitterion form in aqueous solution. The differences in the non-zwitterion pK(a) values were used to estimate the free energy difference between the zwitterion and nonzwitterion forms in solution. The heats of formation of the neutral compounds were calculated from atomization energies and isodesmic reactions to provide the first reliable set of these values in the gas phase. Further calculations were performed on five rare amino acids to predict their heats of formation, acidities, and pK(a) values.

  8. Statistical parameter characteristics of gas-phase fluctuations for gas-liquid intermittent flow

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, G.; Monji, H.; Takaguchi, M. [Univ. of Tsukuba (Japan)

    1995-09-01

    This study deals with theoretical analysis on the general behaviour of statistical parameters of gas-phase fluctuations and comparison of statistical parameter characteristics for the real void fraction fluctuations measured with those for the wave form modified the real fluctuations. In order to investigate the details of the relation between the behavior of the statistical parameters in real intermittent flow and analytical results obtained from information on the real flow, the distributions of statistical parameters for general fundamental wave form of gas-phase fluctuations are discussed in detail. By modifying the real gas-phase fluctuations to a trapezoidaly wave, the experimental results can be directly compared with the analytical results. The analytical results for intermittent flow show that the wave form parameter, and the total amplitude of void fraction fluctuations, affects strongly on the statistical parameter characteristics. The comparison with experiment using nitrogen gas-water intermittent flow suggests that the parameters of skewness and excess may be better as indicators of flow pattern. That is, the macroscopic nature of intermittent flow can be grasped by the skewness and the excess, and the detailed flow structure may be described by the mean and the standard deviation.

  9. Statistical parameter characteristics of gas-phase fluctuations for gas-liquid intermittent flow

    International Nuclear Information System (INIS)

    Matsui, G.; Monji, H.; Takaguchi, M.

    1995-01-01

    This study deals with theoretical analysis on the general behaviour of statistical parameters of gas-phase fluctuations and comparison of statistical parameter characteristics for the real void fraction fluctuations measured with those for the wave form modified the real fluctuations. In order to investigate the details of the relation between the behavior of the statistical parameters in real intermittent flow and analytical results obtained from information on the real flow, the distributions of statistical parameters for general fundamental wave form of gas-phase fluctuations are discussed in detail. By modifying the real gas-phase fluctuations to a trapezoidaly wave, the experimental results can be directly compared with the analytical results. The analytical results for intermittent flow show that the wave form parameter, and the total amplitude of void fraction fluctuations, affects strongly on the statistical parameter characteristics. The comparison with experiment using nitrogen gas-water intermittent flow suggests that the parameters of skewness and excess may be better as indicators of flow pattern. That is, the macroscopic nature of intermittent flow can be grasped by the skewness and the excess, and the detailed flow structure may be described by the mean and the standard deviation

  10. Energy Demodulation Algorithm for Flow Velocity Measurement of Oil-Gas-Water Three-Phase Flow

    Directory of Open Access Journals (Sweden)

    Yingwei Li

    2014-01-01

    Full Text Available Flow velocity measurement was an important research of oil-gas-water three-phase flow parameter measurements. In order to satisfy the increasing demands for flow detection technology, the paper presented a gas-liquid phase flow velocity measurement method which was based on energy demodulation algorithm combing with time delay estimation technology. First, a gas-liquid phase separation method of oil-gas-water three-phase flow based on energy demodulation algorithm and blind signal separation technology was proposed. The separation of oil-gas-water three-phase signals which were sampled by conductance sensor performed well, so the gas-phase signal and the liquid-phase signal were obtained. Second, we used the time delay estimation technology to get the delay time of gas-phase signals and liquid-phase signals, respectively, and the gas-phase velocity and the liquid-phase velocity were derived. At last, the experiment was performed at oil-gas-water three-phase flow loop, and the results indicated that the measurement errors met the need of velocity measurement. So it provided a feasible method for gas-liquid phase velocity measurement of the oil-gas-water three-phase flow.

  11. Monopole excitations of a harmonically trapped one-dimensional Bose gas from the ideal gas to the Tonks-Girardeau regime.

    Science.gov (United States)

    Choi, S; Dunjko, V; Zhang, Z D; Olshanii, M

    2015-09-11

    Using a time-dependent modified nonlinear Schrödinger equation (MNLSE)-where the conventional chemical potential proportional to the density is replaced by the one inferred from Lieb-Liniger's exact solution-we study frequencies of the collective monopole excitations of a one-dimensional Bose gas. We find that our method accurately reproduces the results of a recent experimental study [E. Haller et al., Science 325, 1224 (2009)] in the full spectrum of interaction regimes from the ideal gas, through the mean-field regime, through the mean-field Thomas-Fermi regime, all the way to the Tonks-Giradeau gas. While the former two are accessible by the standard time-dependent NLSE and inaccessible by the time-dependent local density approximation, the situation reverses in the latter case. However, the MNLSE is shown to treat all these regimes within a single numerical method.

  12. Computational phase diagrams of noble gas hydrates under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Teeratchanan, Pattanasak, E-mail: s1270872@sms.ed.ac.uk; Hermann, Andreas, E-mail: a.hermann@ed.ac.uk [Centre for Science at Extreme Conditions and SUPA, School of Physics and Astronomy, The University of Edinburgh, Edinburgh EH9 3FD (United Kingdom)

    2015-10-21

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

  13. Gas phase chromatography of halides of elements 104 and 105

    International Nuclear Information System (INIS)

    Tuerler, A.; Gregorich, K.E.; Czerwinski, K.R.; Hannink, N.J.; Henderson, R.A.; Hoffman, D.C.; Kacher, C.D.; Kadkhodayan, B.; Kreek, S.A.; Lee, D.M.; Leyba, J.D.; Nurmia, M.J.; Gaeggeler, H.W.; Jost, D.T.; Kovacs, J.; Scherer, U.W.; Vermeulen, D.; Weber, A.; Barth, H.; Gober, M.K.; Kratz, J.V.; Bruechle, W.; Schaedel, M.; Schimpf, E.; Gober, M.K.; Kratz, J.V.; Zimmermann, H.P.

    1991-04-01

    On-line isothermal gas phase chromatography was used to study halides of 261 104 (T 1/2 = 65 s) and 262,263 105 (T 1/2 = 34 s and 27 s) produced an atom-at-a time via the reactions 248 Cm( 18 O, 5n) and 249 Bk( 18 O, 5n, 4n), respectively. Using HBr and HCl gas as halogenating agents, we were able to produce volatile bromides and chlorides of the above mentioned elements and study their behavior compared to their lighter homologs in Groups 4 or 5 of the periodic table. Element 104 formed more volatile bromides than its homolog Hf. In contrast, element 105 bromides were found to be less volatile than the bromides of the group 5 elements Nb and Ta. Both 104 and Hf chlorides were observed to be more volatile than their respective bromides. 31 refs., 8 figs

  14. The excitation of an independent-particle gas - classical or quantal - by a time-dependent potential well

    International Nuclear Information System (INIS)

    Blocki, J.; Skalski, J.; Swiatecki, W.J.

    1995-01-01

    A systematic numerical investigation of the excitation of a classical or quantal gas of non-interacting particles in a time-dependent potential well is described. The excitation energy was followed in time for one oscillation around the sphere for six types of deformation: spheroidal shapes and Legendre polynomial ripples P 2 , P 3 , P 4 , P 5 , P 6 , with relative rms amplitudes of 0.2. Ten different speeds of deformation and eleven different values of the diffuseness of the potential well were studied, making altogether 660 quantal and 660 classical time-dependent calculations. In the upper range of deformation speeds the quantal results for the non-integrable shapes P 3 -P 6 agree approximately with the wall formula for dissipation, the deviations being largely accounted for by the wave-mechanical suppression factor of Koonin et al. For low deformation speeds the dissipation becomes dominated by one or two avoided level crossings. (orig.)

  15. Measurement of phase interaction in dispersed gas-particle two-phase flow by phase-doppler anemometry

    Directory of Open Access Journals (Sweden)

    Mergheni Ali Mohamed

    2008-01-01

    Full Text Available For simultaneous measurement of size and velocity distributions of continuous and dispersed phases in a two-phase flow a technique phase-Doppler anemometry was used. Spherical glass particles with a particle diameter range from 102 up to 212 µm were used. In this two-phase flow an experimental results are presented which indicate a significant influence of the solid particles on the flow characteristics. The height of influence of these effects depends on the local position in the jet. Near the nozzle exit high gas velocity gradients exist and therefore high turbulence production in the shear layer of the jet is observed. Here the turbulence intensity in the two-phase jet is decreased compared to the single-phase jet. In the developed zone the velocity gradient in the shear layer is lower and the turbulence intensity reduction is higher. .

  16. Cooperative Excitation and Many-Body Interactions in a Cold Rydberg Gas

    DEFF Research Database (Denmark)

    Viteau, Matthieu; Huillery, Paul; Bason, Mark George

    2012-01-01

    of the dipole blockade is the suppression of fluctuations in the counting statistics of Rydberg excitations, of which some evidence has been found in previous experiments. Here we present experimental results on the dynamics and the counting statistics of Rydberg excitations of ultracold rubidium atoms both...... on and off resonance, which exhibit sub- and super-Poissonian counting statistics, respectively. We compare our results with numerical simulations using a novel theoretical model based on Dicke states of Rydberg atoms including dipole-dipole interactions, finding good agreement between experiment and theory.......The dipole blockade of Rydberg excitations is a hallmark of the strong interactions between atoms in these high-lying quantum states [ M. Saffman, T. G. Walker and K. Mølmer Rev. Mod. Phys. 82 2313 (2010); D. Comparat and P. Pillet J. Opt. Soc. Am. B 27 A208 (2010)]. One of the consequences...

  17. A Compact Fluorescence Lifetime Excitation-Emission Spectrometer (FLEXEMS) for Detecting Trace Organics, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Small Business Innovative Research (SBIR) effort, Leiden Measurement Technology (LMT) proposes to design and build the Fluorescence Lifetime Excitation...

  18. A Compact Fluorescence Lifetime Excitation-Emission Spectrometer (FLEXEMS) for Detecting Trace Organics, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Small Business Innovative Research (SBIR) effort, Leiden Measurement Technology (LMT) proposes to design and build the Fluorescence Lifetime Excitation...

  19. Gas phase spectroscopic study of unstable molecules using FTIR technique

    International Nuclear Information System (INIS)

    Allaf, A.W.; Alibrahim, M.; Kassem, M.

    1998-01-01

    A new route has been developed, leading to the production of phosphorus (III) oxycyanide, OPCN and phosphorus (III) oxycyanate, OPOCN by an on-line process using phosphoryl chloride, POCL 3 as a starting material passed over heated silver at 870 Centigrade and then reacted with AgCN and KOCN heated at 270 Centigrade and 590 Centigrade to produce OPCN and OPOCN respectively. The gas phase fourier transform infrared spectra reported for the first time show the two characterized bonds of OPCN and OPOCN at 2165 cm -1 and 2130 cm -1 , assigned to the C≡N stretching fundamentals of OPCN and OPOCN respectively. (Author)

  20. Gas-phase spectroscopy of ferric heme-NO complexes

    DEFF Research Database (Denmark)

    Wyer, J.A.; Jørgensen, Anders; Pedersen, Bjarke

    2013-01-01

    and significantly blue-shifted compared to ferric heme nitrosyl proteins (maxima between 408 and 422 nm). This is in stark contrast to the Q-band absorption where the protein microenvironment is nearly innocent in perturbing the electronic structure of the porphyrin macrocycle. Photodissociation is primarily...... maxima of heme and its complexes with amino acids and NO. Not so innocent: Weakly bound complexes between ferric heme and NO were synthesised in the gas phase, and their absorption measured from photodissociation yields. Opposite absorption trends in the Soret-band are seen upon NO addition to heme ions...

  1. Broad-line high-excitation gas in the elliptical galaxy NGC5128

    International Nuclear Information System (INIS)

    Phillips, M.M.; Taylor, K.; Axon, D.J.; Atherton, P.D.; Hook, R.N.

    1984-01-01

    A faint, but extensive component of broad-line ionized gas has been discovered in the peculiar giant elliptical galaxy NGC5128. This component has a radically different spatial distribution from the well-studied rotating photoionized gas associated with the dust lane although the velocity fields of the two components are similar. The origin of the broad-line gas is considered as its possible relation to the active nucleus and the X-ray jet discussed. (author)

  2. Raman study of vibrational dynamics of aminopropylsilanetriol in gas phase

    Science.gov (United States)

    Volovšek, V.; Dananić, V.; Bistričić, L.; Movre Šapić, I.; Furić, K.

    2014-01-01

    Raman spectrum of aminopropylsilanetriol (APST) in gas phase has been recorded at room temperature in macro chamber utilizing two-mirror technique over the sample tube. Unlike predominantly trans molecular conformation in condensed phase, the spectra of vapor show that the molecules are solely in gauche conformation with intramolecular hydrogen bond N⋯Hsbnd O which reduces the molecular energy in respect to trans conformation by 0.152 eV. The assignment of the molecular spectra based on the DFT calculation is presented. The strong vibrational bands at 354 cm-1, 588 cm-1 and 3022 cm-1 are proposed for verifying the existence of the ring like, hydrogen bonded structure. Special attention was devoted to the high frequency region, where hydrogen bond vibrations are coupled to stretchings of amino and silanol groups.

  3. Study of two-phase underexpanded jets by gas jet

    International Nuclear Information System (INIS)

    Uchida, Mitsunori; Someya, Satoshi; Okamoto, Koji

    2008-01-01

    When a heat exchange in a Fast Breeder Reactor cracks, a sodium-water reaction occurs. When a tube cracks, highly pressurized water or steam escapes into the surrounding liquid sodium and a sodium-water reaction occurs forming the disodium oxide. The disodium oxide caught in the steam jet strikes other tubes in the reactor. The struck disodium oxide can then cause these tubes to crack. The release of steam into the liquid sodium media is a two-phase flow involving underexpansion. In this paper qualitative measurement of the underexpanded gas jet which injected into water was carried our for the purpose of analyzing the behavior of the two-phase flow. (author)

  4. Molecular hydrogen line ratios in four regions of shock-excited gas

    International Nuclear Information System (INIS)

    Burton, M.G.

    1989-01-01

    Five emission lines of molecular hydrogen, with wavelengths in the ranges of 2.10-2.25 and 3.80-3.85 μm, have been observed in four objects of different type in which the line emission is believed to be excited by shocks. (author)

  5. Closed-cage tungsten oxide clusters in the gas phase.

    Science.gov (United States)

    Singh, D M David Jeba; Pradeep, T; Thirumoorthy, Krishnan; Balasubramanian, Krishnan

    2010-05-06

    During the course of a study on the clustering of W-Se and W-S mixtures in the gas phase using laser desorption ionization (LDI) mass spectrometry, we observed several anionic W-O clusters. Three distinct species, W(6)O(19)(-), W(13)O(29)(-), and W(14)O(32)(-), stand out as intense peaks in the regular mass spectral pattern of tungsten oxide clusters suggesting unusual stabilities for them. Moreover, these clusters do not fragment in the postsource decay analysis. While trying to understand the precursor material, which produced these clusters, we found the presence of nanoscale forms of tungsten oxide. The structure and thermodynamic parameters of tungsten clusters have been explored using relativistic quantum chemical methods. Our computed results of atomization energy are consistent with the observed LDI mass spectra. The computational results suggest that the clusters observed have closed-cage structure. These distinct W(13) and W(14) clusters were observed for the first time in the gas phase.

  6. Surfactants from the gas phase may promote cloud droplet formation.

    Science.gov (United States)

    Sareen, Neha; Schwier, Allison N; Lathem, Terry L; Nenes, Athanasios; McNeill, V Faye

    2013-02-19

    Clouds, a key component of the climate system, form when water vapor condenses upon atmospheric particulates termed cloud condensation nuclei (CCN). Variations in CCN concentrations can profoundly impact cloud properties, with important effects on local and global climate. Organic matter constitutes a significant fraction of tropospheric aerosol mass, and can influence CCN activity by depressing surface tension, contributing solute, and influencing droplet activation kinetics by forming a barrier to water uptake. We present direct evidence that two ubiquitous atmospheric trace gases, methylglyoxal (MG) and acetaldehyde, known to be surface-active, can enhance aerosol CCN activity upon uptake. This effect is demonstrated by exposing acidified ammonium sulfate particles to 250 parts per billion (ppb) or 8 ppb gas-phase MG and/or acetaldehyde in an aerosol reaction chamber for up to 5 h. For the more atmospherically relevant experiments, i.e., the 8-ppb organic precursor concentrations, significant enhancements in CCN activity, up to 7.5% reduction in critical dry diameter for activation, are observed over a timescale of hours, without any detectable limitation in activation kinetics. This reduction in critical diameter enhances the apparent particle hygroscopicity up to 26%, which for ambient aerosol would lead to cloud droplet number concentration increases of 8-10% on average. The observed enhancements exceed what would be expected based on Köhler theory and bulk properties. Therefore, the effect may be attributed to the adsorption of MG and acetaldehyde to the gas-aerosol interface, leading to surface tension depression of the aerosol. We conclude that gas-phase surfactants may enhance CCN activity in the atmosphere.

  7. Coherent Control of Multiphoton Transitions in the Gas and Condensed Phases with Shaped Ultrashort Pulses

    International Nuclear Information System (INIS)

    Dantus, Marcos

    2008-01-01

    Controlling laser-molecule interactions has become an integral part of developing devices and applications in spectroscopy, microscopy, optical switching, micromachining and photochemistry. Coherent control of multiphoton transitions could bring a significant improvement of these methods. In microscopy, multi-photon transitions are used to activate different contrast agents and suppress background fluorescence; coherent control could generate selective probe excitation. In photochemistry, different dissociative states are accessed through two, three, or more photon transitions; coherent control could be used to select the reaction pathway and therefore the yield-specific products. For micromachining and processing a wide variety of materials, femtosecond lasers are now used routinely. Understanding the interactions between the intense femtosecond pulse and the material could lead to technologically important advances. Pulse shaping could then be used to optimize the desired outcome. The scope of our research program is to develop robust and efficient strategies to control nonlinear laser-matter interactions using ultrashort shaped pulses in gas and condensed phases. Our systematic research has led to significant developments in a number of areas relevant to the AMO Physics group at DOE, among them: generation of ultrashort phase shaped pulses, coherent control and manipulation of quantum mechanical states in gas and condensed phases, behavior of isolated molecules under intense laser fields, behavior of condensed phase matter under intense laser field and implications on micromachining with ultrashort pulses, coherent control of nanoparticles their surface plasmon waves and their nonlinear optical behavior, and observation of coherent Coulomb explosion processes at 10 16 W/cm 2 . In all, the research has resulted in 36 publications (five journal covers) and nine invention disclosures, five of which have continued on to patenting

  8. Comparisons between a gas-phase model of silane chemical vapor deposition and laser-diagnostic measurements

    International Nuclear Information System (INIS)

    Breiland, W.G.; Coltrin, M.E.; Ho, P.

    1986-01-01

    Theoretical modeling and experimental measurements have been used to study gas-phase chemistry in the chemical vapor deposition (CVD) of silicon from silane. Pulsed laser Raman spectroscopy was used to obtain temperature profiles and to obtain absolute density profiles of silane during deposition at atmospheric and 6-Torr total pressures for temperatures ranging from 500 to 800 0 C. Laser-excited fluorescence was used to obtain relative density profiles of Si 2 during deposition at 740 0 C in helium with 0-12 Torr added hydrogen. These measurements are compared to predictions from the theoretical model of Coltrin, Kee, and Miller. The predictions agree qualitatively with experiment. These studies indicate that fluid mechanics and gas-phase chemical kinetics are important considerations in understanding the chemical vapor deposition process

  9. Two dimensional laser induced fluorescence in the gas phase: a spectroscopic tool for studying molecular spectroscopy and dynamics

    Science.gov (United States)

    Gascooke, Jason R.; Lawrance, Warren D.

    2017-11-01

    Two dimensional laser induced fluorescence (2D-LIF) extends the usual laser induced fluorescence technique by adding a second dimension, the wavelength at which excited states emit, thereby significantly enhancing the information that can be extracted. It allows overlapping absorption features, whether they arise from within the same molecule or from different molecules in a mixture, to be associated with their appropriate "parent" state and/or molecule. While the first gas phase version of the technique was published a decade ago, the technique is in its infancy, having been exploited by only a few groups to date. However, its potential in gas phase spectroscopy and dynamics is significant. In this article we provide an overview of the technique and illustrate its potential with examples, with a focus on those utilising high resolution in the dispersed fluorescence dimension.

  10. Resonant x-ray emission from gas-phase TiCl{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Hague, C.F.; Tronc, M. [Universite Pierre et Marie Curie, Paris (France); De Groot, F. [Univ. of Groningen (Netherlands)] [and others

    1997-04-01

    Resonant x-ray emission spectroscopy (RXES) has proved to be a powerful tool for studying the electronic structure of condensed matter. Over the past few years it has been used mainly for studying the valence bands of solids and condensed molecules. Very recently the advent of high brightness photon beams provided by third generation synchrotron radiation source undulators, associated with efficient x-ray emission spectrometers has made it possible to perform experiments on free diatomic molecular systems. RXE spectra of free molecules are of prime importance to gain insight into their electronic structure and bonding as they reflect the symmetry of orbitals engaged in the two-electron, two-step process with the l = 0, {+-}2 parity-conserving selection rule, and are free from solid state effects which can introduce difficulties in the interpretation. They provide information (more so than XAS) on the core excited states, and, when performed at fixed incident photon energy as a function of the emitted photon energy, on the electronic excitation (charge transfer, multiplet states). Moreover the anisotropy of the angular distribution of resonant x-ray emission affects the relative intensity of the emission peaks and provides information concerning the symmetries of final states. This is a preliminary report on what are the first RXE spectra of a 3d transition metal complex in the gas phase. The experiment concerns the Ti 3d {yields}2p emission spectrum of TiCl{sub 4} over the 450 to 470 eV region.

  11. Resonant x-ray emission from gas-phase TiCl4

    International Nuclear Information System (INIS)

    Hague, C.F.; Tronc, M.; De Groot, F.

    1997-01-01

    Resonant x-ray emission spectroscopy (RXES) has proved to be a powerful tool for studying the electronic structure of condensed matter. Over the past few years it has been used mainly for studying the valence bands of solids and condensed molecules. Very recently the advent of high brightness photon beams provided by third generation synchrotron radiation source undulators, associated with efficient x-ray emission spectrometers has made it possible to perform experiments on free diatomic molecular systems. RXE spectra of free molecules are of prime importance to gain insight into their electronic structure and bonding as they reflect the symmetry of orbitals engaged in the two-electron, two-step process with the l = 0, ±2 parity-conserving selection rule, and are free from solid state effects which can introduce difficulties in the interpretation. They provide information (more so than XAS) on the core excited states, and, when performed at fixed incident photon energy as a function of the emitted photon energy, on the electronic excitation (charge transfer, multiplet states). Moreover the anisotropy of the angular distribution of resonant x-ray emission affects the relative intensity of the emission peaks and provides information concerning the symmetries of final states. This is a preliminary report on what are the first RXE spectra of a 3d transition metal complex in the gas phase. The experiment concerns the Ti 3d →2p emission spectrum of TiCl 4 over the 450 to 470 eV region

  12. Gas-phase hydrolysis of triplet SO2: A possible direct route to atmospheric acid formation

    Science.gov (United States)

    Donaldson, D. James; Kroll, Jay A.; Vaida, Veronica

    2016-07-01

    Sulfur chemistry is of great interest to the atmospheric chemistry of several planets. In the presence of water, oxidized sulfur can lead to new particle formation, influencing climate in significant ways. Observations of sulfur compounds in planetary atmospheres when compared with model results suggest that there are missing chemical mechanisms. Here we propose a novel mechanism for the formation of sulfurous acid, which may act as a seed for new particle formation. In this proposed mechanism, the lowest triplet state of SO2 (3B1), which may be accessed by near-UV solar excitation of SO2 to its excited 1B1 state followed by rapid intersystem crossing, reacts directly with water to form H2SO3 in the gas phase. For ground state SO2, this reaction is endothermic and has a very high activation barrier; our quantum chemical calculations point to a facile reaction being possible in the triplet state of SO2. This hygroscopic H2SO3 molecule may act as a condensation nucleus for water, giving rise to facile new particle formation (NPF).

  13. Molecular Excitation Energies from Time-Dependent Density Functional Theory Employing Random-Phase Approximation Hessians with Exact Exchange.

    Science.gov (United States)

    Heßelmann, Andreas

    2015-04-14

    Molecular excitation energies have been calculated with time-dependent density-functional theory (TDDFT) using random-phase approximation Hessians augmented with exact exchange contributions in various orders. It has been observed that this approach yields fairly accurate local valence excitations if combined with accurate asymptotically corrected exchange-correlation potentials used in the ground-state Kohn-Sham calculations. The inclusion of long-range particle-particle with hole-hole interactions in the kernel leads to errors of 0.14 eV only for the lowest excitations of a selection of three alkene, three carbonyl, and five azabenzene molecules, thus surpassing the accuracy of a number of common TDDFT and even some wave function correlation methods. In the case of long-range charge-transfer excitations, the method typically underestimates accurate reference excitation energies by 8% on average, which is better than with standard hybrid-GGA functionals but worse compared to range-separated functional approximations.

  14. Effects of phase and coupling between the vibrational modes on selective excitation in coherent anti-Stokes Raman scattering microscopy

    International Nuclear Information System (INIS)

    Patel, Vishesha; Malinovsky, Vladimir S.; Malinovskaya, Svetlana

    2010-01-01

    Coherent anti-Stokes Raman scattering (CARS) microscopy has been a major tool of investigation of biological structures as it contains the vibrational signature of molecules. A quantum control method based on chirped pulse adiabatic passage was recently proposed for selective excitation of a predetermined vibrational mode in CARS microscopy [Malinovskaya and Malinovsky, Opt. Lett. 32, 707 (2007)]. The method utilizes the chirp sign variation at the peak pulse amplitude and gives a robust adiabatic excitation of the desired vibrational mode. Using this method, we investigate the impact of coupling between vibrational modes in molecules on controllability of excitation of the CARS signal. We analyze two models of two coupled two-level systems (TLSs) having slightly different transitional frequencies. The first model, featuring degenerate ground states of the TLSs, gives robust adiabatic excitation and maximum coherence in the resonant TLS for positive value of the chirp. In the second model, implying nondegenerate ground states in the TLSs, a population distribution is observed in both TLSs, resulting in a lack of selectivity of excitation and low coherence. It is shown that the relative phase and coupling between the TLSs play an important role in optimizing coherence in the desired vibrational mode and suppressing unwanted transitions in CARS microscopy.

  15. Frequency metrology of a photomixing source for gas phase spectroscopy

    Science.gov (United States)

    Hindle, Francis; Mouret, Gael; Yang, Chun; Cuisset, Arnaud; Bocquet, Robin; Lours, Michel; Rovera, Daniele

    2010-08-01

    The availability of frequency combs has opened new possibilities for the measurement of optical frequencies. Photomixing is an attractive solution for high resolution THz spectroscopy of gases due to the narrow spectral resolution and ability to access the 100 GHz to 3.5 THz range. One limitation of present photomixing spectrometers is the accuracy with which the THz frequency is established. Measurement of the centre frequency gas phase molecular transitions requires an accuracy better than 100 kHz in order to allow spectroscopic constants to be determined. Standard optical techniques like those employed in wavelength meters can only provide accuracies in the order of 50 MHz. We have used a turnkey fibre based frequency comb and a standard photomixing configuration to realize a THz synthesizer with an accuracy of around 50kHz. Two ECDLs used to pump the photomixer are phase locked onto the frequency comb and provide a tuning range of 10 MHz. In order to extend the tuning range an additional phase locked ECLD has been added to obtain a range in excess of 100 MHz. The absorption profiles of many Doppler limited transitions of carbonyl sulphide and formaldehyde have been measured to validate this instrument.

  16. Use of CFD to predict trapped gas excitation as source of vibration and noise in screw compressors

    Science.gov (United States)

    Willie, James

    2017-08-01

    This paper investigates the source of noise in oil free screw compressors mounted on highway trucks and driven by a power take-off (PTO) transmission system. Trapped gas at the discharge side is suggested as possible source of the excitation of low frequency torsional resonance in these compressors that can lead to noise and vibration. Measurements and lumped mass torsional models have shown low frequency torsional resonance in the drive train of these compressors when they are mounted on trucks. This results in high torque peak at the compressor input shaft and in part to pulsating noise inside the machine. The severity of the torque peak depends on the amplitude of the input torque fluctuation from the drive (electric motor or truck engine). This in turn depends on the prop-shaft angle. However, the source of the excitation of this low torsional resonance inside the machine is unknown. Using CFD with mesh motion at every 1° rotation of the rotors, it is shown that the absence of a pressure equalizing chamber at the discharge can lead to trapped gas creation, which can lead to over-compression, over-heating of the rotors, and to high pressure pulsations at the discharge. Over-compression can lead to shock wave generation at the discharge plenum and the pulsation in pressure can lead to noise generation. In addition, if the frequency of the pressure pulsation in the low frequency range coincides with the first torsional frequency of the drive train the first torsional resonance mode can be excited.

  17. Ionization steps and phase-space metamorphoses in the pulsed microwave ionization of highly excited hydrogen atoms

    International Nuclear Information System (INIS)

    Bayfield, J.E.; Luie, S.Y.; Perotti, L.C.; Skrzypkowski, M.P.

    1996-01-01

    As the peak electric field of the microwave pulse is increased, steps in the classical microwave ionization probability of the highly excited hydrogen atom are produced by phase-space metamorphosis. They arise from new layers of Kolmogorov-Arnold-Moser (KAM) islands being exposed as KAM surfaces are destroyed. Both quantum numerical calculations and laboratory experiments exhibit the ionization steps, showing that such metamorphoses influence pulsed semiclassical systems. copyright 1996 The American Physical Society

  18. Regenerable Air Purification System for Gas-Phase Contaminant Control

    Science.gov (United States)

    Constantinescu, Ileana C.; Finn, John E.; LeVan, M. Douglas; Lung, Bernadette (Technical Monitor)

    2000-01-01

    Tests of a pre-prototype regenerable air purification system (RAPS) that uses water vapor to displace adsorbed contaminants from an adsorbent column have been performed at NASA Ames Research Center. A unit based on this design can be used for removing trace gas-phase contaminants from spacecraft cabin air or from polluted process streams including incinerator exhaust. During the normal operation mode, contaminants are removed from the air on the column. Regeneration of the column is performed on-line. During regeneration, contaminants are displaced and destroyed inside the closed oxidation loop. In this presentation we discuss initial experimental results for the performance of RAPS in the removal and treatment of several important spacecraft contaminant species from air.

  19. Synthesis and Gas Phase Thermochemistry of Germanium-Containing Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Classen, Nathan Robert [Iowa State Univ., Ames, IA (United States)

    2002-01-01

    The driving force behind much of the work in this dissertation was to gain further understanding of the unique olefin to carbene isomerization observed in the thermolysis of 1,1-dimethyl-2-methylenesilacyclobutane by finding new examples of it in other silicon and germanium compounds. This lead to the examination of a novel phenylmethylenesilacyclobut-2-ene, which did not undergo olefin to carbene rearrangement. A synthetic route to methylenegermacyclobutanes was developed, but the methylenegermacyclobutane system exhibited kinetic instability, making the study of the system difficult. In any case the germanium system decomposed through a complex mechanism which may not include olefin to carbene isomerization. However, this work lead to the study of the gas phase thermochemistry of a series of dialkylgermylene precursors in order to better understand the mechanism of the thermal decomposition of dialkylgermylenes. The resulting dialkylgermylenes were found to undergo a reversible intramolecular β C-H insertion mechanism.

  20. Conformational Study of Taurine in the Gas Phase

    Science.gov (United States)

    Cortijo, Vanessa; Sanz, M. Eugenia; López, Juan C.; Alonso, José L.

    2009-08-01

    The conformational preferences of the amino sulfonic acid taurine (NH2-CH2-CH2-SO3H) have been investigated in the gas phase by laser ablation molecular beam Fourier transform microwave spectroscopy (LA-MB-FTMW) in the 6-14 GHz frequency range. One conformer has been observed, and its rotational, centrifugal distortion, and hyperfine quadrupole coupling constants have been determined from the analysis of its rotational spectrum. Comparison of the experimental constants with those calculated theoretically identifies the detected conformer unambiguously. The observed conformer of taurine is stabilized by an intramolecular hydrogen bond O-H···N between the hydrogen of the sulfonic acid group and the nitrogen atom of the amino group.

  1. Technical Procedures Management in Gas-Phase Detoxification Laboratory

    International Nuclear Information System (INIS)

    Cardona Garcia, A. I.; Sanchez Cabrero, B.

    2000-01-01

    The natural cycle of Volatile Organic Compounds (VOCs) has been disturbed by the industrial and socioeconomic activities of human beings. This imbalance in the environment has affected the ecosystems and the human health. Initiatives have been planned to mitigate these adverse effects. In order to minimize the hazardous effects, initiatives have been proposed for the treatment of gaseous emissions. The solar photo catalysis appears as a clear and renewable technology in front of the conventional ones.In CIEMAT this line is being investigated as the base of a future implementation at a pre industrial scale.Technical procedures are written in this document for testing Gas-Phase detoxification at lab scale in the Renewable Energy Department (DER) CIEMAT- Madrid to eliminate the VOCs by using the solar photo catalysis technology. (Author) 34 refs

  2. Gas-phase synthesis of magnetic metal/polymer nanocomposites

    Science.gov (United States)

    Starsich, Fabian H. L.; Hirt, Ann M.; Stark, Wendelin J.; Grass, Robert N.

    2014-12-01

    Highly magnetic metal Co nanoparticles were produced via reducing flame spray pyrolysis, and directly coated with an epoxy polymer in flight. The polymer content in the samples varied between 14 and 56 wt% of nominal content. A homogenous dispersion of Co nanoparticles in the resulting nanocomposites was visualized by electron microscopy. The size and crystallinity of the metallic fillers was not affected by the polymer, as shown by XRD and magnetic hysteresis measurements. The good control of the polymer content in the product nanocomposite was shown by elemental analysis. Further, the successful polymerization in the gas phase was demonstrated by electron microscopy and size measurements. The presented effective, dry and scalable one-step synthesis method for highly magnetic metal nanoparticle/polymer composites presented here may drastically decrease production costs and increase industrial yields.

  3. Gas-Phase Thermolysis of a Thioketen-S-Oxide

    DEFF Research Database (Denmark)

    Carlsen, Lars; Egsgaard, Helge; Schaumann, Ernst

    1980-01-01

    The unimolecular gas-phase thermolytic decomposition of 1,1,3,3-tetramethyl-2-thiocarbonylcyclohexane S-oxide (3) has been studied as a function of temperature by a flash vacuum thermolysis (f.v.t.) technique. The products detected are the carbenes (4) and (5), the ketone (6), the keten (7......), the thioketone (8), and the thioketen (9). The product ratio is highly dependent on the thermolysis temperature. The thermolysis of (3) is mechanistically rationalized by assuming the existence of only two concurrent primary processes, which are (a) extrusion of atomic oxygen, leading to the thioketen (9...... and CSO leading to the carbenes (5) and (4), respectively, are observed. Owing to an apparently very short half-life of the oxathiiran (10), only the decomposition products of the three-membered ring compound have been detected. These are the thioketone (8), formed by rearrangement of (10) into the α...

  4. Statistical Physics of Nanoparticles in the Gas Phase

    CERN Document Server

    Hansen, Klavs

    2013-01-01

    Thermal processes are ubiquitous and an understanding of thermal phenomena is essential for a complete description of the physics of nanoparticles, both for the purpose of modeling the dynamics of the particles and for the correct interpretation of experimental data. This book has the twofold aim to present coherently the relevant results coming from the recent scientific literature and to guide the readers through the process of deriving results, enabling them to explore the limits of the mathematical approximations and test the power of the method. The book is focused on the fundamental properties of nanosystems in the gas phase. For this reason there is a strong emphasis on microcanonical physics. Each chapter is enriched with exercises and 3 Appendices provide additional useful materials.

  5. Multiphase flow and transport caused by spontaneous gas phase growth in the presence of dense non-aqueous phase liquid.

    Science.gov (United States)

    Roy, James W; Smith, James E

    2007-01-30

    Disconnected bubbles or ganglia of trapped gas may occur below the top of the capillary fringe through a number of mechanisms. In the presence of dense non-aqueous phase liquid (DNAPL), the disconnected gas phase experiences mass transfer of dissolved gases, including volatile components from the DNAPL. The properties of the gas phase interface can also change. This work shows for the first time that when seed gas bubbles exist spontaneous gas phase growth can be expected to occur and can significantly affect water-gas-DNAPL distributions, fluid flow, and mass transfer. Source zone behaviour was observed in three different experiments performed in a 2-dimensional flow cell. In each case, a DNAPL pool was created in a zone of larger glass beads over smaller glass beads, which served as a capillary barrier. In one experiment effluent water samples were analyzed to determine the vertical concentration profile of the plume above the pool. The experiments effectively demonstrated a) a cycle of spontaneous gas phase expansion and vertical advective mobilization of gas bubbles and ganglia above the DNAPL source zone, b) DNAPL redistribution caused by gas phase growth and mobilization, and c) that these processes can significantly affect mass transport from a NAPL source zone.

  6. Gapless Spin Excitations in the Field-Induced Quantum Spin Liquid Phase of alpha-RuCl3

    OpenAIRE

    Zheng, Jiacheng; Ran, Kejing; Li, Tianrun; Wang, Jinghui; Wang, Pengshuai; Liu, Bin; Liu, Zhengxin; Normand, B.; Wen, Jinsheng; Yu, Weiqiang

    2017-01-01

    $\\alpha$-RuCl$_3$ is a leading candidate material for theobservation of physics related to the Kitaev quantum spin liquid (QSL). By combined susceptibility, specific-heat, and nuclear-magnetic-resonance measurements, we demonstrate that $\\alpha$-RuCl$_3$ undergoes a quantum phase transition to a QSL in a magnetic field of 7.5 T applied in the $ab$ plane. We show further that this high-field QSL phase has gapless spin excitations over a field range up to 16 T. This highly unconventional result...

  7. Gapless Spin Excitations in the Field-Induced Quantum Spin Liquid Phase of α -RuCl3

    Science.gov (United States)

    Zheng, Jiacheng; Ran, Kejing; Li, Tianrun; Wang, Jinghui; Wang, Pengshuai; Liu, Bin; Liu, Zheng-Xin; Normand, B.; Wen, Jinsheng; Yu, Weiqiang

    2017-12-01

    α -RuCl3 is a leading candidate material for the observation of physics related to the Kitaev quantum spin liquid (QSL). By combined susceptibility, specific-heat, and nuclear-magnetic-resonance measurements, we demonstrate that α -RuCl3 undergoes a quantum phase transition to a QSL in a magnetic field of 7.5 T applied in the a b plane. We show further that this high-field QSL phase has gapless spin excitations over a field range up to 16 T. This highly unconventional result, unknown in either Heisenberg or Kitaev magnets, offers insight essential to establishing the physics of α -RuCl3 .

  8. Precursor-Less Coating of Nanoparticles in the Gas Phase

    Directory of Open Access Journals (Sweden)

    Tobias V. Pfeiffer

    2015-03-01

    Full Text Available This article introduces a continuous, gas-phase method for depositing thin metallic coatings onto (nanoparticles using a type of physical vapor deposition (PVD at ambient pressure and temperature. An aerosol of core particles is mixed with a metal vapor cloud formed by spark ablation by passing the aerosol through the spark zone using a hollow electrode configuration. The mixing process rapidly quenches the vapor, which condenses onto the core particles at a timescale of several tens of milliseconds in a manner that can be modeled as bimodal coagulation. Gold was deposited onto core nanoparticles consisting of silver or polystyrene latex, and silver was deposited onto gold nanoparticles. The coating morphology depends on the relative surface energies of the core and coating materials, similar to the growth mechanisms known for thin films: a coating made of a substance having a high surface energy typically results in a patchy coverage, while a coating material with a low surface energy will normally “wet” the surface of a core particle. The coated particles remain gas-borne, allowing further processing.

  9. Response of a thermal barrier system to acoustic excitation in a gas turbine nuclear reactor

    International Nuclear Information System (INIS)

    Betts, W.S. Jr.; Blevins, R.D.

    1980-11-01

    A gas turbine located within a High-Temperature Gas-Cooled Reactor (HTGR) induces high acoustic sound pressure levels into the primary coolant (helium). This acoustic loading induces high cycle fatigue stresses which may control the design of the thermal barrier system. This study examines the dynamic response of a thermal barrier configuration consisting of a fibrous insulation compressed against the reactor vessel by a coverplate which is held in position by a central attachment fixture. The results of dynamic vibration analyses indicate the effect of the plate size and curvature and the attachment size on the response of the thermal barrier

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

    KAUST Repository

    Zhang, J.-Y.; Qian, Ying; Schwingenschlö gl, Udo; Yan, Z.-C.

    2013-01-01

    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

  11. Atomic and molecular physics in the gas phase

    International Nuclear Information System (INIS)

    Toburen, L.H.

    1990-09-01

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

  12. Electron-beam synthesis of fuel in the gas phase

    International Nuclear Information System (INIS)

    Ponomarev, A.V.; Holodkova, E.M.; Ershov, B.G.

    2011-01-01

    Complete text of publication follows. Tendencies of world development focus attention on a vegetative biomass as on the major raw resource for future chemistry and a fuel industry. The significant potential for perfection of biomass conversion processes is concentrated in the field of radiation-chemical methods. Both the mode of post-radiation distillation and mode of electron-beam distillation of biomass have been investigated as well as the mode of gas-phase synthesis of liquid engine fuel from of biomass distillation products. Synergistic action of radiation and temperature has been analyzed at use of the accelerated electron beams allowing to combine radiolysis with effective radiation heating of a material without use of additional heaters. At dose rate above 1 kGy/s the electron-beam irradiation results in intensive decomposition of a biomass and evaporation of formed fragments with obtaining of a liquid condensate (∼ 60 wt%), CO 2 and Co gases (13-18 wt%) and charcoal in the residue. Biomass distillation at radiation heating allows to increase almost three times an organic liquid yield in comparison with pyrolysis. The majority of liquid products from cellulose is represented by the furan derivatives considered among the very perspective components for alternative engine fuels. Distilled-off gases and vapors are diluted with gaseous C 1 -C 5 alkanes and again are exposed to an irradiation to produce liquid fuel from a biomass. This transformation is based on a method of electron-beam circulation conversion of gaseous C 1 -C 5 alkanes (Ponomarev, A.V., Radiat. Phys. Chem., 78, 48, 2009) which consists in formation and removal of liquid products with high degree of carbon skeleton branching. The isomers ratio in a liquid may be controlled by means of change of an irradiation condition and initial gas composition. The irradiation of gaseous alkanes together with vaporous products of biomass destruction allows to synthesize the fuel enriched by conventional

  13. Possibilities of gas-phase radio-chromatography application to permanent-gas analysis

    International Nuclear Information System (INIS)

    Dupuis, M.C.; Charrier, G.; Alba, C.; Massimino, D.

    1970-01-01

    The gas-phase radio-chromatography technique has been applied to the rapid analysis of permanent gases (H 2 , O 2 , N 2 , A, Kr, Xe, CO, CH 4 ) labelled with radioactive indicators ( 3 H, 37 A, 85 Kr, 133 Xe). After calibration, the components of such a mixture can be identified and their concentrations measured in less than two hours, using a sample volume of from 0.1 to 10 cm 3 . The minimum detectable activity is of the order of 10 -4 μC for each radioactive isotope. The measurements are reproducible to about 2 to 3 per cent. This work has been mainly concerned with the influence of parameters affecting the response of the radioactivity detector (ionization chamber or gas flow proportional counter). The method has very numerous applications both theoretically, for the study of chromatographic phenomena under ideal conditions (infinitesimal concentrations made possible by the use of radioactive tracers), and practically, for rapid and accurate radiochemical analysis of radioactive gas mixtures. (authors) [fr

  14. Strongly gapped spin-wave excitation in the insulating phase of NaOsO3

    International Nuclear Information System (INIS)

    Calder, S.; Vale, J. G.; Bogdanov, N.; Donnerer, C.

    2017-01-01

    NaOsO_3 hosts a rare manifestation of a metal-insulator transition driven by magnetic correlations, placing the magnetic exchange interactions in a central role. We use resonant inelastic x-ray scattering to directly probe these magnetic exchange interactions. A dispersive and strongly gapped (58 meV) excitation is observed indicating appreciable spin-orbit coupling in this 5d"3 system. The excitation is well described within a minimal model Hamiltonian with strong anisotropy and Heisenberg exchange (J_1 = J_2 = 13.9 meV). As a result, the observed behavior places NaOsO_3 on the boundary between localized and itinerant magnetism.

  15. Design comparison of single phase outer and inner-rotor hybrid excitation flux switching motor for hybrid electric vehicles

    Science.gov (United States)

    Mazlan, Mohamed Mubin Aizat; Sulaiman, Erwan; Husin, Zhafir Aizat; Othman, Syed Muhammad Naufal Syed; Khan, Faisal

    2015-05-01

    In hybrid excitation machines (HEMs), there are two main flux sources which are permanent magnet (PM) and field excitation coil (FEC). These HEMs have better features when compared with the interior permanent magnet synchronous machines (IPMSM) used in conventional hybrid electric vehicles (HEVs). Since all flux sources including PM, FEC and armature coils are located on the stator core, the rotor becomes a single piece structure similar with switch reluctance machine (SRM). The combined flux generated by PM and FEC established more excitation fluxes that are required to produce much higher torque of the motor. In addition, variable DC FEC can control the flux capabilities of the motor, thus the machine can be applied for high-speed motor drive system. In this paper, the comparisons of single-phase 8S-4P outer and inner rotor hybrid excitation flux switching machine (HEFSM) are presented. Initially, design procedures of the HEFSM including parts drawing, materials and conditions setting, and properties setting are explained. Flux comparisons analysis is performed to investigate the flux capabilities at various current densities. Then the flux linkages of PM with DC FEC of various DC FEC current densities are examined. Finally torque performances are analyzed at various armature and FEC current densities for both designs. As a result, the outer-rotor HEFSM has higher flux linkage of PM with DC FEC and higher average torque of approximately 10% when compared with inner-rotor HEFSM.

  16. Spatial profiling of ion and neutral excitation in noble gas electron cyclotron resonance plasmas

    International Nuclear Information System (INIS)

    Rhoades, R.L.; Gorbatkin, S.M.

    1994-01-01

    Optical emission from neutrals and ions of several noble gases has been profiled in an electron cyclotron resonance plasma system. In argon plasmas with a net microwave power of 750 W, the neutral (696.5-nm) and ion (488-nm) emission profiles are slightly center peaked at 0.32 mTorr and gradually shift to a hollow appearance at 2.5 mTorr. Neon profiles show a similar trend from 2.5 to 10.0 mTorr. For the noble gases, transition pressure scales with the ionization potential of the gas, which is consistent with neutral depletion. Studies of noble gas mixtures, however, indicate that neutral depletion is not always dominant in the formation of hollow profiles. For Kr/Ar, Ar/Ne, and Ne/He plasmas, the majority gas tends to set the overall shape of the profile at any given pressure. For the conditions of the current system, plasma density appears to be more dominant than electron temperature in the formation of hollow profiles. The general method described is also a straightforward, inexpensive technique for measuring the spatial distribution of power deposited in plasmas, particularly where absolute scale can be calibrated by some other means

  17. Efficient excitation of nonlinear phonons via chirped pulses: Induced structural phase transitions

    Science.gov (United States)

    Itin, A. P.; Katsnelson, M. I.

    2018-05-01

    Nonlinear phononics play important role in strong laser-solid interactions. We discuss a dynamical protocol for efficient phonon excitation, considering recent inspiring proposals: inducing ferroelectricity in paraelectric perovskites, and inducing structural deformations in cuprates [Subedi et al., Phys. Rev. B 89, 220301(R) (2014), 10.1103/PhysRevB.89.220301; Phys. Rev. B 95, 134113 (2017), 10.1103/PhysRevB.95.134113]. High-frequency phonon modes are driven by midinfrared pulses, and coupled to lower-frequency modes those indirect excitations cause structural deformations. We study in more detail the case of KTaO3 without strain, where it was not possible to excite the needed low-frequency phonon mode by resonant driving of the higher frequency one. Behavior of the system is explained using a reduced model of coupled driven nonlinear oscillators. We find a dynamical mechanism which prevents effective excitation at resonance driving. To induce ferroelectricity, we employ driving with sweeping frequency, realizing so-called capture into resonance. The method can be applied to many other related systems.

  18. Amplitude and phase of surface plasmon polaritons excited at a step edge

    DEFF Research Database (Denmark)

    Klick, Alwin; de la Cruz, Sergio; Lemke, Christoph

    2016-01-01

    A combined experimental and theoretical study on the laser-induced excitation of surface plasmon polaritons (SPP) at well-defined step edges of a gold–vacuum interface is presented. As a relevant parameter determining the coupling efficiency between laser field and SPP, we identify the ratio betw...

  19. Theory of propagation of spectrum and correlations of radiation in optically dense gas in the case of the closed excitation contour

    International Nuclear Information System (INIS)

    Barantsev, K.A.; Litvinov, A.N.; Popov, E.N.

    2017-01-01

    This work is devoted to generalization of the semi-classical theory of interaction of broadband laser radiation with the atomic gas at the room temperature in the cell in the case of the closed excitation contour. The atomic density matrix equations and spectrum and correlations transport equations have been derived for excitation by fluctuating field with Gaussian statistics. It is shown that the spatial oscillations of radiation intensity and atomic density matrix can be excited. It was found that such medium can serve as a filter of incoherent part of the radiation.

  20. Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces.

    Science.gov (United States)

    Spezia, Riccardo; Martínez-Nuñez, Emilio; Vazquez, Saulo; Hase, William L

    2017-04-28

    In this Introduction, we show the basic problems of non-statistical and non-equilibrium phenomena related to the papers collected in this themed issue. Over the past few years, significant advances in both computing power and development of theories have allowed the study of larger systems, increasing the time length of simulations and improving the quality of potential energy surfaces. In particular, the possibility of using quantum chemistry to calculate energies and forces 'on the fly' has paved the way to directly study chemical reactions. This has provided a valuable tool to explore molecular mechanisms at given temperatures and energies and to see whether these reactive trajectories follow statistical laws and/or minimum energy pathways. This themed issue collects different aspects of the problem and gives an overview of recent works and developments in different contexts, from the gas phase to the condensed phase to excited states.This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'. © 2017 The Author(s).

  1. HIGHLY EXCITED H{sub 2} IN HERBIG–HARO 7: FORMATION PUMPING IN SHOCKED MOLECULAR GAS?

    Energy Technology Data Exchange (ETDEWEB)

    Pike, R. E. [Department of Physics and Astronomy, University of Victoria, Victoria, BC (Canada); Geballe, T. R. [Gemini Observatory, Hilo, HI (United States); Burton, M. G. [School of Physics, University of New South Wales, Sydney (Australia); Chrysostomou, A. [Centre for Astrophysics Research, University of Hertfordshire (United Kingdom)

    2016-05-10

    We have obtained K -band spectra at R ∼ 5000 and an angular resolution of 0.″3 of a section of the Herbig–Haro 7 (HH7) bow shock, using the Near-Infrared Integral Field Spectrograph at Gemini North. Present in the portion of the data cube corresponding to the brightest part of the bow shock are emission lines of H{sub 2} with upper state energies ranging from ∼6000 K to the dissociation energy of H{sub 2}, ∼50,000 K. Because of low signal-to-noise ratios, the highest excitation lines cannot be easily seen elsewhere in the observed region. However, excitation temperatures, measured throughout much of the observed region using lines from levels as high as 25,000 K, are a strong function of upper level energy, indicating that the very highest levels are populated throughout. The level populations in the brightest region are well fit by a two-temperature model, with 98.5% of the emitting gas at T = 1800 K and 1.5% at T = 5200 K. The bulk of the H{sub 2} line emission in HH7, from the 1800 K gas, has previously been well-modeled by a continuous shock, but the 5200 K cozmponent is inconsistent with standalone standard continuous shock models. We discuss various possible origins for the hot component and suggest that this component is H{sub 2} newly reformed on dust grains and then ejected from them, presumably following dissociation of some of the H{sub 2} by the shock.

  2. Gas-phase synthesis of semiconductor nanocrystals and its applications

    Science.gov (United States)

    Mandal, Rajib

    Luminescent nanomaterials is a newly emerging field that provides challenges not only to fundamental research but also to innovative technology in several areas such as electronics, photonics, nanotechnology, display, lighting, biomedical engineering and environmental control. These nanomaterials come in various forms, shapes and comprises of semiconductors, metals, oxides, and inorganic and organic polymers. Most importantly, these luminescent nanomaterials can have different properties owing to their size as compared to their bulk counterparts. Here we describe the use of plasmas in synthesis, modification, and deposition of semiconductor nanomaterials for luminescence applications. Nanocrystalline silicon is widely known as an efficient and tunable optical emitter and is attracting great interest for applications in several areas. To date, however, luminescent silicon nanocrystals (NCs) have been used exclusively in traditional rigid devices. For the field to advance towards new and versatile applications for nanocrystal-based devices, there is a need to investigate whether these NCs can be used in flexible and stretchable devices. We show how the optical and structural/morphological properties of plasma-synthesized silicon nanocrystals (Si NCs) change when they are deposited on stretchable substrates made of polydimethylsiloxane (PDMS). Synthesis of these NCs was performed in a nonthermal, low-pressure gas phase plasma reactor. To our knowledge, this is the first demonstration of direct deposition of NCs onto stretchable substrates. Additionally, in order to prevent oxidation and enhance the luminescence properties, a silicon nitride shell was grown around Si NCs. We have demonstrated surface nitridation of Si NCs in a single step process using non?thermal plasma in several schemes including a novel dual-plasma synthesis/shell growth process. These coated NCs exhibit SiNx shells with composition depending on process parameters. While measurements including

  3. Using a heterodyne vibrometer in combination with pulse excitation for primary calibration of ultrasonic hydrophones in amplitude and phase

    Science.gov (United States)

    Weber, Martin; Wilkens, Volker

    2017-08-01

    A high-frequency vibrometer was used with ultrasonic pulse excitation in order to perform a primary hydrophone calibration. This approach enables the simultaneous characterization of the amplitude and phase transfer characteristic of ultrasonic hydrophones. The method allows a high frequency resolution in a considerably short time for the measurement. Furthermore, the uncertainty contributions of this approach were investigated and quantified. A membrane hydrophone was calibrated and the uncertainty budget for this measurement was determined. The calibration results are presented up to 70~\\text{MHz} . The measurement results show good agreement with the results obtained by sinusoidal burst excitation through the use of the vibrometer and by a homodyne laser interferometer, with RMS deviation of approximately 3% -4% in the frequency range from 1 to 60~\\text{MHz} . Further hydrophones were characterized up to 100~\\text{MHz} with this procedure to demonstrate the suitability for very high frequency calibration.

  4. Excited State Dynamics and Semiconductor-to-Metallic Phase Transition of VO2 Thin Film

    National Research Council Canada - National Science Library

    Liu, Huimin

    2004-01-01

    .... Vanadium dioxide shows an ultrafast, passive phase transition (PT) from a monoclinic semiconductor phase to a metallic tetragonal rutile structure when the sample temperature is above 68 degrees C...

  5. Characterization of condensed phase nitric acid particles formed in the gas phase

    Institute of Scientific and Technical Information of China (English)

    Long Jia; Yongfu Xu

    2011-01-01

    The formation of nitric acid hydrates has been observed in a chamber during the dark reaction of NO2 with O3 in the presence of air.The size of condensed phase nitric acid was measured to be 40-100 nm and 20-65 nm at relative humidity (RH) ≤ 5% and RH = 67% under our experimental conditions, respectively.The nitric acid particles were collected on the glass fiber membrane and their chemical compositions were analyzed by infrared spectrum.The main components of nitric acid hydrates in particles are HNO3·3H2O and NO3-·xH2O (x≥ 4) at low RH, whereas at high RH HNO3·H2O, HNO3·2H2O, HNO3·3H2O and NO3-·xH2O (x≥ 4) all exist in the condensed phase.At high RH HNO3·xH2O (x ≤ 3) collected on the glass fiber membrane is greatly increased, while NO3-·xH2O (x ≥4) decreased, compared with low RH.To the best of our knowledge, this is the first time to report that condensed phase nitric acid can be generated in the gas phase at room temperature.

  6. Gas Detectors Performance in CMS and Excited Muon Search Feasibility Study at 14 teV

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00572294; Mahrous, Ayman; Yasein, Mohamed Nabil

    Within the Standard Model(SM) of particle physics, quarks and leptons are understood to be the fundamental particles and Their existence have been verified experimentally. A search for substructure of quarks or study of quark compositeness is carried out with the CMS detector at LHC, using $ 300 fb^{-1} $ of integrated luminosity at a center-of-mass energy$ \\sqrt{s} =14 TeV $. The discovery of excited muons ($ \\mu^{*} $) would be a first indication of lepton compositeness. In the current study, $ \\mu^{*} $ is assumed to be produced via four-fermions contact interactions in association with a muon ($ \\mu $) and to decay via the gauge mediated process $ \\mu^{*} \\to \\mu\\gamma$, yielding a final state with two muons and a photon. Monte Carlo (MC) samples are produced via MadGraph5 and PYTHIA 8 event generators. To simulate the detector response, GEANT4 which interfaced to CMS software was used for full simulation and Delphes was used for fast simulation, assuming the CMS detector configuration. Objects and ev...

  7. Uptake of Organic Gas Phase Species by 1-Methylnaphthalene

    Science.gov (United States)

    Zhang, H.; Xia, J.; Davidovits, P.; Jayne, J. T.; Kolb, C. E.; Worsnop, D. R.

    2002-12-01

    Using a droplet train apparatus, the mass accommodation coefficients (α) on 1-methylnapthalene of gas phase m-xylene, ethylbenzene, butylbenzene, α-pinene, γ-terpinene, and 2-methyl-2-hexanol were measured as a function of temperature (265 K to 296 K). 1-methylnapthalene was selected as a surrogate for hydrophobic and aromatic hydrocarbons found in tropospheric aerosols. The mass accommodation coefficients (α) of all the molecules obtained from these measurements exhibit negative temperature dependence. The upper and lower values of α at 265 K and 296 K respectively are: for m-xylene 0.44 and 0.26; for ethylbenzene 0.37 and 0.22; for butylbenzene 0.47 and 0.31; for α-pinene 0.47 and 0.096; for γ-terpinene 0.39 and 0.12; for 2-methyl-2-hexanol 0.44 and 0.26. The uptake measurements also yielded values for the product HDl1/2 for most of the molecules studied (H = Henry's law constant, Dl = liquid phase diffusion coefficient). Using calculated values of Dl the Henry's law constant is obtained, and expressed in the form ln H (M/atm) = -A + B/T. The A and B values for the molecules studied are listed in Table 1. Table 1: A and B values for the Henry's law constant H expressed as ln H (M/atm) = -A + B/T \\ m-xylene: A=7.20, B=4060\\ethylbenzene: A=5.81, B=3660\\butylbenzene: A=16.95, B=7330α-pinene: A=15.69, B=6360\\2-methyl-2-hexanol: A=9.95, B=4760

  8. Cavity-enhanced Raman spectroscopy with optical feedback cw diode lasers for gas phase analysis and spectroscopy.

    Science.gov (United States)

    Salter, Robert; Chu, Johnny; Hippler, Michael

    2012-10-21

    A variant of cavity-enhanced Raman spectroscopy (CERS) is introduced, in which diode laser radiation at 635 nm is coupled into an external linear optical cavity composed of two highly reflective mirrors. Using optical feedback stabilisation, build-up of circulating laser power by 3 orders of magnitude occurs. Strong Raman signals are collected in forward scattering geometry. Gas phase CERS spectra of H(2), air, CH(4) and benzene are recorded to demonstrate the potential for analytical applications and fundamental molecular studies. Noise equivalent limits of detection in the ppm by volume range (1 bar sample) can be achieved with excellent linearity with a 10 mW excitation laser, with sensitivity increasing with laser power and integration time. The apparatus can be operated with battery powered components and can thus be very compact and portable. Possible applications include safety monitoring of hydrogen gas levels, isotope tracer studies (e.g., (14)N/(15)N ratios), observing isotopomers of hydrogen (e.g., radioactive tritium), and simultaneous multi-component gas analysis. CERS has the potential to become a standard method for sensitive gas phase Raman spectroscopy.

  9. Method and apparatus for transport, introduction, atomization and excitation of emission spectrum for quantitative analysis of high temperature gas sample streams containing vapor and particulates without degradation of sample stream temperature

    Science.gov (United States)

    Eckels, David E.; Hass, William J.

    1989-05-30

    A sample transport, sample introduction, and flame excitation system for spectrometric analysis of high temperature gas streams which eliminates degradation of the sample stream by condensation losses.

  10. AN ANALYSIS OF CO PRODUCTION IN COMETARY COMAE: CONTRIBUTIONS FROM GAS-PHASE PHENOMENA

    International Nuclear Information System (INIS)

    Pierce, Donna M.; A'Hearn, Michael F.

    2010-01-01

    Understanding the sources of CO in cometary comae is important for understanding comet chemistry and the roles comets have played in the development of the solar system. Among comets sampled to date, the CO abundances vary widely and no direct correlation of CO abundance with other known comet properties has been identified. The picture is complicated further by the discovery of CO production in the comae of some comets, most notably comets Halley and Hale-Bopp. In this study, we investigate the conditions under which CO can be produced in the coma via gas-phase phenomena. We include photochemistry of several parent molecules, as well as two-body chemical reactions that involve the parents and their photodissociative daughter and granddaughter products. We also consider the level of excitation of 'hot' hydrogen (H*) and O( 1 D) in the network, because the level of excitation of these reactants strongly influences reaction rates. Our results suggest that the dominant gas-phase contributor to CO formation is the photodissociation of H 2 CO. Even though typical abundances of H 2 CO are at ∼1% relative to water in the coma, it produces more CO than other processes due to its relatively short photodissociation lifetime. Because other studies have shown H 2 CO to have a distributed source as well, it suggests that at least some CO formation in the coma is connected to the H 2 CO distributed source. We take the time to examine the CO 2 /CO ratio and note that while the CO 2 /CO ratio in comets Halley, Hale-Bopp, and Hyakutake are noticeably different when only native CO is considered, the CO 2 /CO ratios show greater similarity when total CO is considered. Although this sample is relatively small, should the relatively similar CO 2 /CO Total ratio of ∼0.25 indeed be constant for comets with distributed CO sources, it suggests that the extended CO source of these comets is tied directly to the overall C, H, O chemistry of comets, as is likely to happen if hydrogenation

  11. Numerical simulation for gas-liquid two-phase flow in pipe networks

    International Nuclear Information System (INIS)

    Li Xiaoyan; Kuang Bo; Zhou Guoliang; Xu Jijun

    1998-01-01

    The complex pipe network characters can not directly presented in single phase flow, gas-liquid two phase flow pressure drop and void rate change model. Apply fluid network theory and computer numerical simulation technology to phase flow pipe networks carried out simulate and compute. Simulate result shows that flow resistance distribution is non-linear in two phase pipe network

  12. Portable vibration exciter

    Science.gov (United States)

    Beecher, L. C.; Williams, F. T.

    1970-01-01

    Gas-driven vibration exciter produces a sinusoidal excitation function controllable in frequency and in amplitude. It allows direct vibration testing of components under normal loads, removing the possibility of component damage due to high static pressure.

  13. Multi-Phase Combustion and Transport Processes Under the Influence of Acoustic Excitation

    Science.gov (United States)

    2014-01-01

    waveguide. Alcohol fuels (ethanol and methonal) as well as aviation fuel replacements ( Fischer -Tropsch (FT) synfuel and an FT blend with JP-8) were studied...replacements ( Fischer -Tropsch (FT) synfuel and an FT blend with JP-8) were studied here. During acoustic excitation, the flame surrounding the droplet was...Wegener is approved. Chris R. Anderson Jeff D. Eldredge Ivett A. Leyva Owen I. Smith Ann R. Karagozian, Committee Chair University of California, Los

  14. GAS-PHASE CHEMISTRY OF THE CYANATE ION, OCN−

    International Nuclear Information System (INIS)

    Cole, Callie A.; Wang, Zhe-Chen; Bierbaum, Veronica M.; Snow, Theodore P.

    2015-01-01

    Cyanate (OCN − ) is the only ion to date whose presence has been confirmed in the icy mantles that coat interstellar dust grains. Understanding the chemical behavior of cyanate at a fundamental level is therefore integral to the advancement of astrochemistry. We seek to unravel the chemistry of this intriguing anion through a combination of gas-phase experiments and theoretical explorations. Our approach is twofold: first, employing a flowing afterglow-selected ion flow tube apparatus, the reactions between OCN − and three of the most abundant atomic species in the interstellar medium, hydrogen, nitrogen, and oxygen, are examined. Hydrogen atoms readily react by associative detachment, but the remarkable stability of OCN − does not give rise to an observable reaction with either nitrogen or oxygen atoms. To explain these results, the potential energy surfaces of several reactions are investigated at the B3LYP/6-311++G(d,p) level of theory. Second, collision induced dissociation experiments involving deprotonated uracil, thymine, and cytosine in an ion trap mass spectrometer reveal an interesting connection between these pyrimidine nucleobase anions and OCN − . Theoretical calculations at the B3LYP/6-311++G(d,p) level of theory are performed to delineate the mechanisms of dissociation and explore the possible role of OCN − as a biomolecule precursor

  15. Gas phase reactions of nitrogen oxides with olefins

    Energy Technology Data Exchange (ETDEWEB)

    Altshuller, A P; Cohen, I

    1961-01-01

    The nature of the condensation products formed in the gas phase reactions of nitrogen dioxide and nitric oxide with pentene-1, 2-methylbutene-2, and 2-methylbutadiene-1,3 was investigated. The reactants were combined at partial pressures in the range of 0.1 to 2.5 mm with the total pressure at one atmosphere. The products were determined by infrared and ultraviolet spectroscopy and colorimetry. The condensates included primary and secondary nitro compounds and alkyl nitrates. Strong hydroxyl and single bond carbon to oxygen stretching vibrations indicate the presence of either nitroalcohols or simple aliphatic alcohols formed through oxidation reactions. Carbonyl stretching frequencies observable in some of the reactions support the conclusion that a portion of the reactants disappear by oxidation rather than by nitration processes. The available results do not indicate the presence of appreciable amounts of tert.-nitro compounds, conjugated nitro-olefins, or gem-dinitro-alkanes. The reactivities of the olefins with the nitrogen oxides are in the decreasing order: 2-methyl-butadiene-1,3, 2-methylbutene-2, pentene-1. 20 references.

  16. 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.

  17. High excitation of the species in nitrogen–aluminum plasma generated by electron cyclotron resonance microwave discharge of N2 gas and pulsed laser ablation of Al target

    International Nuclear Information System (INIS)

    Liang, Peipei; Li, Yanli; Cai, Hua; You, Qinghu; Yang, Xu; Huang, Feiling; Sun, Jian; Xu, Ning; Wu, Jiada

    2014-01-01

    A reactive nitrogen–aluminum plasma generated by electron cyclotron resonance (ECR) microwave discharge of N 2 gas and pulsed laser ablation of an Al target is characterized spectroscopically by time-integrated and time-resolved optical emission spectroscopy (OES). The vibrational and rotational temperatures of N 2 species are determined by spectral simulation. The generated plasma strongly emits radiation from a variety of excited species including ambient nitrogen and ablated aluminum and exhibits unique features in optical emission and temperature evolution compared with the plasmas generated by a pure ECR discharge or by the expansion of the ablation plume. The working N 2 gas is first excited by ECR discharge and the excitation of nitrogen is further enhanced due to the fast expansion of the aluminum plume induced by target ablation, while the excitation of the ablated aluminum is prolonged during the plume expansion in the ECR nitrogen plasma, resulting in the formation of strongly reactive nitrogen–aluminum plasma which contains highly excited species with high vibrational and rotational temperatures. The enhanced intensities and the prolonged duration of the optical emissions of the combined plasma would provide an improved analytical capability for spectrochemical analysis. - Highlights: • ECR discharge and pulsed laser ablation generate highly excited ECR–PLA plasma. • The expansion of PLA plasma results in excitation enhancement of ECR plasma species. • The ECR plasma leads to excitation prolongation of PLA plasma species. • The ECR–PLA plasma emits strong emissions from a variety of excited species. • The ECR–PLA plasma maintains high vibrational–rotational temperatures for a long time

  18. Polarized-neutron-scattering study of the spin-wave excitations in the 3-k ordered phase of uranium antimonide.

    Science.gov (United States)

    Magnani, N; Caciuffo, R; Lander, G H; Hiess, A; Regnault, L-P

    2010-03-24

    The anisotropy of magnetic fluctuations propagating along the [1 1 0] direction in the ordered phase of uranium antimonide has been studied using polarized inelastic neutron scattering. The observed polarization behavior of the spin waves is a natural consequence of the longitudinal 3-k magnetic structure; together with recent results on the 3-k-transverse uranium dioxide, these findings establish this technique as an important tool to study complex magnetic arrangements. Selected details of the magnon excitation spectra of USb have also been reinvestigated, indicating the need to revise the currently accepted theoretical picture for this material.

  19. Homolytic iodination and nitration of some benzene derivatives in the gas phase

    International Nuclear Information System (INIS)

    Vonk, W.F.M.

    1980-01-01

    Two gas phase reactions, involving the iodination and nitration of benzene derivatives, are described. The experimental techniques of the apparatus and the methods used are outlined. The kinetic H/D isotope effect in the gas phase nitration of benzene with NO 2 is determined. (C.F.)

  20. A direct comparison of protein structure in the gas and solution phase: the Trp-cage

    DEFF Research Database (Denmark)

    Patriksson, Alexandra; Adams, Christopher M; Kjeldsen, Frank

    2007-01-01

    Molecular dynamics simulations of zwitterions of the Trp-cage protein in the gas phase show that the most stable ion in vacuo has preserved the charge locations acquired in solution. A direct comparison of the gas and solution-phase structures reveals that, despite the similarity in charge location...

  1. Importance of the gas phase role to the prediction of energetic material behavior: An experimental study

    International Nuclear Information System (INIS)

    Ali, A.N.; Son, S.F.; Asay, B.W.; Sander, R.K.

    2005-01-01

    Various thermal (radiative, conductive, and convective) initiation experiments are performed to demonstrate the importance of the gas phase role in combustion modeling of energetic materials (EM). A previously published condensed phase model that includes a predicted critical irradiance above which ignition is not possible is compared to experimental laser ignition results for octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and 2,4,6-trinitrotoluene (TNT). Experimental results conflict with the predicted critical irradiance concept. The failure of the model is believed to result from a misconception about the role of the gas phase in the ignition process of energetic materials. The model assumes that ignition occurs at the surface and that evolution of gases inhibits ignition. High speed video of laser ignition, oven cook-off and hot wire ignition experiments captures the ignition of HMX and TNT in the gas phase. A laser ignition gap test is performed to further evaluate the effect of gas phase laser absorption and gas phase disruption on the ignition process. Results indicate that gas phase absorption of the laser energy is probably not the primary factor governing the gas phase ignition observations. It is discovered that a critical gap between an HMX pellet and a salt window of 6 mm±0.4 mm exists below which ignition by CO 2 laser is not possible at the tested irradiances of 29 W/cm 2 and 38 W/cm 2 for HMX ignition. These observations demonstrate that a significant disruption of the gas phase, in certain scenarios, will inhibit ignition, independent of any condensed phase processes. These results underscore the importance of gas phase processes and illustrate that conditions can exist where simple condensed phase models are inadequate to accurately predict the behavior of energetic materials

  2. Importance of the gas phase role to the prediction of energetic material behavior: An experimental study

    Science.gov (United States)

    Ali, A. N.; Son, S. F.; Asay, B. W.; Sander, R. K.

    2005-03-01

    Various thermal (radiative, conductive, and convective) initiation experiments are performed to demonstrate the importance of the gas phase role in combustion modeling of energetic materials (EM). A previously published condensed phase model that includes a predicted critical irradiance above which ignition is not possible is compared to experimental laser ignition results for octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and 2,4,6-trinitrotoluene (TNT). Experimental results conflict with the predicted critical irradiance concept. The failure of the model is believed to result from a misconception about the role of the gas phase in the ignition process of energetic materials. The model assumes that ignition occurs at the surface and that evolution of gases inhibits ignition. High speed video of laser ignition, oven cook-off and hot wire ignition experiments captures the ignition of HMX and TNT in the gas phase. A laser ignition gap test is performed to further evaluate the effect of gas phase laser absorption and gas phase disruption on the ignition process. Results indicate that gas phase absorption of the laser energy is probably not the primary factor governing the gas phase ignition observations. It is discovered that a critical gap between an HMX pellet and a salt window of 6mm±0.4mm exists below which ignition by CO2 laser is not possible at the tested irradiances of 29W /cm2 and 38W/cm2 for HMX ignition. These observations demonstrate that a significant disruption of the gas phase, in certain scenarios, will inhibit ignition, independent of any condensed phase processes. These results underscore the importance of gas phase processes and illustrate that conditions can exist where simple condensed phase models are inadequate to accurately predict the behavior of energetic materials.

  3. Gas holdup in a reciprocating plate bioreactor: Non-Newtonian - liquid phase

    Directory of Open Access Journals (Sweden)

    Naseva Olivera S.

    2002-01-01

    Full Text Available The gas holdup was studied in non-newtonian liquids in a gas-liquid and gas-liquid-solid reciprocating plate bioreactor. Aqueous solutions of carboxy methyl cellulose (CMC; Lucel, Lučane, Yugoslavia of different degrees of polymerization (PP 200 and PP 1000 and concentration (0,5 and 1%, polypropylene spheres (diameter 8.3 mm; fraction of spheres: 3.8 and 6.6% by volume and air were used as the liquid, solid and gas phase. The gas holdup was found to be dependent on the vibration rate, the superficial gas velocity, volume fraction of solid particles and Theological properties of the liquid ohase. Both in the gas-liquid and gas-liquid-solid systems studied, the gas holdup increased with increasing vibration rate and gas flow rate. The gas holdup was higher in three-phase systems than in two-phase ones under otter operating conditions being the same. Generally the gas holdup increased with increasing the volume fraction of solid particles, due to the dispersion action of the solid particles, and decreased with increasing non-Newtonian behaviour (decreasing flow index i.e. with increasing degree of polymerization and solution concentration of CMC applied, as a result of gas bubble coalescence.

  4. Gas concentration and temperature in acoustically excited Delft turbulent jet flames

    Energy Technology Data Exchange (ETDEWEB)

    Ana Maura A. Rocha; Joao A. Carvalho Jr.; Pedro T. Lacava [Sao Paulo State University, Guaratingueta (Brazil)

    2008-11-15

    This paper shows the experimental results for changes in the flame structure when acoustic fields are applied in natural gas Delft turbulent diffusion flames. The acoustic field (pulsating combustion) generates zones of intense mixture of reactants in the flame region, promoting a more complete combustion and, consequently, lower pollutant emissions, increase in convective heat transfer rates, and lower fuel consumption. The results show that the presence of the acoustic field changes drastically the flame structure, mainly in the burner natural frequencies. However, for higher acoustic amplitudes, or acoustic pressures, a hydrogen pilot flame is necessary in order to keep the main flame anchored. In the flame regions where the acoustic field is more intense, premixed flame characteristics were observed. Besides, the pulsating regime modifies the axial and radial combustion structure, which could be verified by the radial distribution of concentrations of O{sub 2}, CO, CO{sub 2}, and NOx, and by the temperature profile. The experiments also presented the reduction of flame length with the increase of acoustic amplitude. 30 refs., 15 figs., 3 tabs.

  5. Spin-orbit excitation energies, anisotropic exchange, and magnetic phases of honeycomb RuCl3

    OpenAIRE

    Yadav, Ravi; Bogdanov, Nikolay A.; Katukuri, Vamshi M.; Nishimoto, Satoshi; Brink, Jeroen van den; Hozoi, Liviu

    2016-01-01

    Large anisotropic exchange in 5d and 4d oxides and halides open the door to new types of magnetic ground states and excitations, inconceivable a decade ago. A prominent case is the Kitaev spin liquid, host of remarkable properties such as protection of quantum information and the emergence of Majorana fermions. Here we discuss the promise for spin-liquid behavior in the 4d 5 honeycomb halide ?-RuCl3. From advanced electronic-structure calculations, we find that the Kitaev interaction is ferro...

  6. Gapless Spin Excitations in the Field-Induced Quantum Spin Liquid Phase of α-RuCl_{3}.

    Science.gov (United States)

    Zheng, Jiacheng; Ran, Kejing; Li, Tianrun; Wang, Jinghui; Wang, Pengshuai; Liu, Bin; Liu, Zheng-Xin; Normand, B; Wen, Jinsheng; Yu, Weiqiang

    2017-12-01

    α-RuCl_{3} is a leading candidate material for the observation of physics related to the Kitaev quantum spin liquid (QSL). By combined susceptibility, specific-heat, and nuclear-magnetic-resonance measurements, we demonstrate that α-RuCl_{3} undergoes a quantum phase transition to a QSL in a magnetic field of 7.5 T applied in the ab plane. We show further that this high-field QSL phase has gapless spin excitations over a field range up to 16 T. This highly unconventional result, unknown in either Heisenberg or Kitaev magnets, offers insight essential to establishing the physics of α-RuCl_{3}.

  7. The properties of gas-phase multiply charged ions

    International Nuclear Information System (INIS)

    Newson, K.A.

    1999-01-01

    This thesis presents the results of a series of experiments investigating the reactivity of gas-phase molecular dications with various neutral collision partners, at collision energies between 3 and 13 eV in the laboratory frame, using a crossed-beam apparatus. The experiment involves the measurement of product ion intensities, which are determined by means of time-of-flight mass spectrometry. The experimental apparatus and methodology, together with the areas of theory important to ion chemistry, are described in the thesis. The product ions of greatest interest are those ions formed by bond-forming (chemical) reactivity. The relative intensities of such product ions, and those ions formed as a result of electron-transfer reactions, are, when recorded as a function of the collision energy, a powerful probe of the reaction mechanism. Additionally, where appropriate, the reactions are examined for isotope effects by using the isotopic analogue of the neutral collision partner. The results of the experiments indicate that no intermolecular isotope effects are present in the reactions of CF 2 2+ and CF 3 2+ with H 2 and D 2 neutral targets. In addition, the observed collision energy dependence is symptomatic of the absence of a barrier to reaction. These observations suggest that the reactions proceed via an impulsive direct reaction mechanism. Such a conclusion casts doubt on the applicability of the Landau-Zener model of H - /D - transfer reactivity. Other results presented in this thesis include the first reported observation of a bond-forming reaction between a molecular dication (CF2 2+ ) and a polyatomic neutral species (NH 3 ). Finally, the branching ratio of the products of bond-forming reactions between CF 2 2+ with HD indicates the operation of a strong intramolecular isotope effect, favouring the formation of the deuterated product. This observation points to a reaction mechanism in which the bond-formation is preceded by electron-transfer. (author)

  8. Dissociative electron attachment to the gas-phase nucleobase hypoxanthine

    Energy Technology Data Exchange (ETDEWEB)

    Dawley, M. Michele [Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Tanzer, Katrin; Denifl, Stephan, E-mail: Stephan.Denifl@uibk.ac.at, E-mail: Sylwia.Ptasinska.1@nd.edu [Institut für Ionenphysik und Angewandte Physik, and Center for Molecular Biosciences Innsbruck (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck (Austria); Carmichael, Ian [Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Ptasińska, Sylwia, E-mail: Stephan.Denifl@uibk.ac.at, E-mail: Sylwia.Ptasinska.1@nd.edu [Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2015-06-07

    We present high-resolution measurements of the dissociative electron attachment (DEA) to isolated gas-phase hypoxanthine (C{sub 5}H{sub 4}N{sub 4}O, Hyp), a tRNA purine base. The anion mass spectra and individual ion efficiency curves from Hyp were measured as a function of electron energy below 9 eV. The mass spectra at 1 and 6 eV exhibit the highest anion yields, indicating possible common precursor ions that decay into the detectable anionic fragments. The (Hyp − H) anion (C{sub 5}H{sub 3}N{sub 4}O{sup −}) exhibits a sharp resonant peak at 1 eV, which we tentatively assign to a dipole-bound state of the keto-N1H,N9H tautomer in which dehydrogenation occurs at either the N1 or N9 position based upon our quantum chemical computations (B3LYP/6-311+G(d,p) and U(MP2-aug-cc-pVDZ+)) and prior studies with adenine. This closed-shell dehydrogenated anion is the dominant fragment formed upon electron attachment, as with other nucleobases. Seven other anions were also observed including (Hyp − NH){sup −}, C{sub 4}H{sub 3}N{sub 4}{sup −}/C{sub 4}HN{sub 3}O{sup −}, C{sub 4}H{sub 2}N{sub 3}{sup −}, C{sub 3}NO{sup −}/HC(HCN)CN{sup −}, OCN{sup −}, CN{sup −}, and O{sup −}. Most of these anions exhibit broad but weak resonances between 4 and 8 eV similar to many analogous anions from adenine. The DEA to Hyp involves significant fragmentation, which is relevant to understanding radiation damage of biomolecules.

  9. Gas-Phase Combustion Synthesis of Aluminum Nitride Powder

    Science.gov (United States)

    Axelbaum, R. L.; Lottes, C. R.; Huertas, J. I.; Rosen, L. J.

    1996-01-01

    Due to its combined properties of high electrical resistivity and high thermal conductivity aluminum nitride (AlN) is a highly desirable material for electronics applications. Methods are being sought for synthesis of unagglomerated, nanometer-sized powders of this material, prepared in such a way that they can be consolidated into solid compacts having minimal oxygen content. A procedure for synthesizing these powders through gas-phase combustion is described. This novel approach involves reacting AlCl3, NH3, and Na vapors. Equilibrium thermodynamic calculations show that 100% yields can be obtained for these reactants with the products being AlN, NaCl, and H2. The NaCl by-product is used to coat the AlN particles in situ. The coating allows for control of AlN agglomeration and protects the powders from hydrolysis during post-flame handling. On the basis of thermodynamic and kinetic considerations, two different approaches were employed to produce the powder, in co-flow diffusion flame configurations. In the first approach, the three reactants were supplied in separate streams. In the second, the AlCl3 and NH3 were premixed with HCl and then reacted with Na vapor. X-ray diffraction (XRD) spectra of as-produced powders show only NaCl for the first case and NaCl and AlN for the second. After annealing at 775 C tinder dynamic vacuum, the salt was removed and XRD spectra of powders from both approaches show only AlN. Aluminum metal was also produced in the co-flow flame by reacting AlCl3 with Na. XRD spectra of as-produced powders show the products to be only NaCl and elemental aluminum.

  10. Continuous fixed-bed gas-phase hydroformylation using supported ionic liquid-phase (SILP) Rh catalysts

    DEFF Research Database (Denmark)

    Riisager, Anders; Wasserscheid, Peter; Van Hal, R.

    2003-01-01

    Continuous flow gas-phase hydroformylation of propene was performed using novel supported ionic liquid-phase (SILP) catalysts containing immobilized Rh complexes of the biphosphine ligand sulfoxantphos in the ionic liquids 1-n-butyl-3-methylimidazolium hexafluorophosphate and halogen-free 1-n-butyl...

  11. Gas Phase Rovibrational Spectroscopy of Dmso, Part II: Towards the Terahertz Observation of 4-FOLD Clusters

    Science.gov (United States)

    Cuisset, Arnaud; Martin-Drumel, Marie-Aline; Hindle, Francis; Mouret, Gael; Sadovskii, Dmitrii A.

    2013-06-01

    Benefiting of the exceptional properties of the AILES synchrotron beamline, the gas phase Far-IR spectrum of DMSO has been recorded and resolved. The rovibrational analysis allowed to discover a new rotational behaviour for a polyatomic molecule: the gyroscopic destabilization. In order to explain this phenomenon, we looked for four-fold energy clusters in the high resolution ground state THz spectrum of DMSO recorded with a sub-THz spectrometer based on a frequency multiplication chain. Pure rotational lines in the 5 lowest vibrationnally excited levels have been recorded below 700 GHz. With near 1000 rotational transitions assigned, high quantum numbers have been reached allowing to discover sequence of four-fold clusters in the out of plane bending mode of DMSO and to study the vibrational dependence of an unusual rotational dynamics. J. B. Brubach et al., AIP Conf. Proc., 1214, (81), 2010. A. Cuisset, L. Nanobashvili, I. Smirnova, R. Bocquet, F. Hindle, G. Mouret, O. Pirali, P. Roy, D. Sadovskii,Chem. Phys. Lett., 492,(30),2010 A. Cuisset, O. Pirali, D. Sadovskii,Phys. Rev. Lett., 109,(094101), 2012. G. Mouret, M. Guinet, A. Cuisset, L. Croizet, S. Eliet, R. Bocquet, F. Hindle, IEEE Sensors Journal, 13, 1, 2013.

  12. Engineered Materials for Advanced Gas Turbine Engine, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will develop innovative composite powders and composites that will surpass the properties of currently identified materials for advanced gas turbine...

  13. Phase Fluctuations and the Absence of Topological Defects in Photo-excited Charge Ordered Nickelate

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W.S.; Chuang, Y.D.; Moore, R.G.; Zhu, Y.; Patthey, L.; Trigo, M.; Lu, D.H.; Kirchmann, P.S.; Krupin, O.; Yi, M.; Langner, M.; Huse, N.; Robinson, J.S.; Chen, Y.; Zhou, S.Y.; Coslovich, G.; Huber, B.; Reis, D.A.; Kaindl, R.A.; Schoenlein, R.W.; Doering, D.

    2012-05-15

    The dynamics of an order parameter's amplitude and phase determines the collective behaviour of novel states emerging in complex materials. Time- and momentum-resolved pump-probe spectroscopy, by virtue of measuring material properties at atomic and electronic time scales out of equilibrium, can decouple entangled degrees of freedom by visualizing their corresponding dynamics in the time domain. Here we combine time-resolved femotosecond optical and resonant X-ray diffraction measurements on charge ordered La{sub 1.75}Sr{sub 0.25}NiO{sub 4} to reveal unforeseen photoinduced phase fluctuations of the charge order parameter. Such fluctuations preserve long-range order without creating topological defects, distinct from thermal phase fluctuations near the critical temperature in equilibrium. Importantly, relaxation of the phase fluctuations is found to be an order of magnitude slower than that of the order parameter's amplitude fluctuations, and thus limits charge order recovery. This new aspect of phase fluctuations provides a more holistic view of the phase's importance in ordering phenomena of quantum matter.

  14. Gas phase adsorption technology for nitrogen isotope separation and its feasibility for highly enriched nitrogen gas production

    International Nuclear Information System (INIS)

    Inoue, Masaki; Asaga, Takeo

    2000-04-01

    Highly enriched nitrogen-15 gas is favorable to reduce radioactive carbon-14 production in reactor. The cost of highly enriched nitrogen-15 gas in mass production is one of the most important subject in nitride fuel option in 'Feasibility Study for FBR and Related Fuel Cycle'. In this work gas phase adsorption technology was verified to be applicable for nitrogen isotope separation and feasible to produce highly enriched nitrogen-15 gas in commercial. Nitrogen isotopes were separated while ammonia gas flows through sodium-A type zeolite column using pressure swing adsorption process. The isotopic ratio of eight samples were measured by high resolution mass spectrometry and Fourier transform microwave spectroscopy. Gas phase adsorption technology was verified to be applicable for nitrogen isotope separation, since the isotopic ratio of nitrogen-15 and nitrogen-14 in samples were more than six times as high as in natural. The cost of highly enriched nitrogen-15 gas in mass production were estimated by the factor method. It revealed that highly enriched nitrogen-15 gas could be supplied in a few hundred yen per gram in mass production. (author)

  15. Laser-induced gratings in the gas phase excited via Raman-active transitions

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, D N [General Physics Inst., Russian Academy of Sciences, Moscow (Russian Federation); Bombach, R; Hemmerling, B; Hubschmid, W [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    We report on a new time resolved coherent Raman technique that is based on the generation of thermal gratings following a population change among molecular levels induced by stimulated Raman pumping. This is achieved by spatially and temporally overlapping intensity interference patterns generated independently by two lasers. When this technique is used in carbon dioxide, employing transitions which belong to the Q-branches of the {nu}{sub 1}/2{nu}{sub 2} Fermi dyad, it is possible to investigate molecular energy transfer processes. (author) 2 figs., 10 refs.

  16. Real time observation of the excimer formation dynamics of a gas phase benzene dimer by picosecond pump-probe spectroscopy.

    Science.gov (United States)

    Miyazaki, Mitsuhiko; Fujii, Masaaki

    2015-10-21

    We observed the real-time excimer (EXC) formation dynamics of a gas phase benzene dimer (Bz2) cluster after photo-excitation to the S1 state by applying an ionization detected picosecond transient absorption method for probing the visible EXC absorption for the first time. The time evolution of the EXC absorption from the S1 0(0) level shows a rise that is well fitted by a single exponential function with a time constant of 18 ± 2 ps. The structure of the Bz dimer has a T-shaped structure in the ground electronic state, and that in the EXC state is a parallel sandwich (SW) structure. Thus, the observed rise time corresponds to the structural change from the T to the SW structures, which directly shows the EXC formation. On the other hand, the EXC formation after excitation of the S1 6(1) vibrational level of the stem site showed a faster rise of the time constant of 10 ± 2 ps. Supposing equilibrium between the EXC and the local excited states, it followed that the intramolecular vibrational energy redistribution rate of the 6(1) level is largely enhanced and becomes faster than the EXC formation reaction.

  17. Novel spin excitation in the high field phase of an S=1 antiferromagnetic chain

    International Nuclear Information System (INIS)

    Hagiwara, M.; Kashiwagi, T.; Kimura, S.; Honda, Z.; Kindo, K.

    2007-01-01

    We report the results of high-field multi-frequency ESR experiment on the S=1 Heisenberg antiferromagnetic chain Ni(C 5 H 14 N 2 ) 2 N 3 (PF 6 ) for the fields up to about 55T and the frequencies up to about 2THz. We have found that excitation branches above the critical field (H c ) where the energy gap closes change into one branch around 15T which becomes close to the paramagnetic line at high fields. The branch above 15T fits well the conventional antiferromagnetic resonance mode with easy planar anisotropy. We compare the results with those in a weakly coupled antiferromagnetic dimer compound KCuCl 3 and discuss the origin of the branches observed above H c

  18. Possibility of determining the concentration of the gas phase in a two-phase stream by an acoustical method

    Energy Technology Data Exchange (ETDEWEB)

    Butenko, A N; Potapenko, A E; Chistyakov, E S

    1976-01-01

    The method is based on the recording of the amplitude-frequency characteristics of a circular piezoelectric resonator (sensor) during movement of a stream of a two-phase medium. It is shown that the electrical voltage drop across the transducer and the natural oscillating frequency of the transducer depend on the concentration of the gas phase in the two-phase mixture, allowing an instrument to be developed for measurement of this concentration.

  19. Two-phase gas bubble-liquid boundary layer flow along vertical and inclined surfaces

    International Nuclear Information System (INIS)

    Cheung, F.B.; Epstein, M.

    1985-01-01

    The behavior of a two-phase gas bubble-liquid boundary layer along vertical and inclined porous surfaces with uniform gas injection is investigated experimentally and analytically. Using argon gas and water as the working fluids, a photographical study of the two-phase boundary layer flow has been performed for various angles of inclination ranging from 45 0 to 135 0 and gas injection rates ranging from 0.01 to 0.1 m/s. An integral method has been employed to solve the system of equations governing the two-phase motion. The effects of the gas injection rate and the angle of inclination on the growth of the boundary layer have been determined. The predicted boundary layer thickness is found to be in good agreement with the experimental results. The calculated axial liquid velocity and the void fraction in the two-phase region are also presented along with the observed flow behavior

  20. Evolution of the Normal State of a Strongly Interacting Fermi Gas from a Pseudogap Phase to a Molecular Bose Gas

    International Nuclear Information System (INIS)

    Perali, A.; Palestini, F.; Pieri, P.; Strinati, G. C.; Stewart, J. T.; Gaebler, J. P.; Drake, T. E.; Jin, D. S.

    2011-01-01

    Wave-vector resolved radio frequency spectroscopy data for an ultracold trapped Fermi gas are reported for several couplings at T c , and extensively analyzed in terms of a pairing-fluctuation theory. We map the evolution of a strongly interacting Fermi gas from the pseudogap phase into a fully gapped molecular Bose gas as a function of the interaction strength, which is marked by a rapid disappearance of a remnant Fermi surface in the single-particle dispersion. We also show that our theory of a pseudogap phase is consistent with a recent experimental observation as well as with quantum Monte Carlo data of thermodynamic quantities of a unitary Fermi gas above T c .

  1. An improved excitation control technique of three-phase induction machine operating as dual winding generator for micro-wind domestic application

    International Nuclear Information System (INIS)

    Chatterjee, Arunava; Chatterjee, Debashis

    2015-01-01

    Highlights: • A three-phase induction machine working as single phase generator is studied. • The generator is assisted by an inverter and photovoltaic panel for excitation. • Proposed control involves operating the machine as balanced two-phase generator. • Torque pulsations associated with unbalanced phase currents are minimized. • The generator can be used for grid-isolated micro-wind power generation. - Abstract: Single-phase generation schemes are widely utilized for harnessing wind power in remote and grid secluded applications. This paper presents a novel control methodology for a three-phase induction machine working as a single-phase dual winding induction generator. Three-phase induction machines providing single-phase output with proper control strategy can be beneficial in grid secluded micro-wind energy conversion systems compared to single-phase induction generators. Three-phase induction machines operating in single-phase mode are mostly excited asymmetrically to provide single-phase power leading to unbalanced current flow in the stator windings causing heating and insulation breakdown. The asymmetrical excitation also initiates torque pulsations which results in additional stress and vibration at the machine shaft and bearings degrading the machine performance. The proposed control is chiefly aimed to minimize this unbalance. The variable excitation required for the proposed generator is provided through a single-phase inverter with photovoltaic panels. The suitability for such a generator along with its control is tested with appropriate simulations and experimental results. The induction generator with the proposed control strategy is expected to be useful in remote and grid isolated households as a standalone source of single-phase electrical power

  2. Excited-state quantum phase transitions studied from a non-Hermitian perspective

    Czech Academy of Sciences Publication Activity Database

    Šindelka, Milan; Santos, L.F.; Moiseyev, N.

    2017-01-01

    Roč. 95, č. 1 (2017), s. 1-5, č. článku 010103. ISSN 2469-9926 R&D Projects: GA MŠk LG15013 Institutional support: RVO:68378271 Keywords : exceptional points * systems * model * signatures * dynamics * freedom * spectra Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.925, year: 2016

  3. Generation, Detection and characterization of Gas-Phase Transition Metal containing Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Steimle, Timothy [Arizona State Univ., Tempe, AZ (United States)

    2015-12-15

    The objective of this project was to generate, detect, and characterize small, gas-phase, metal containing molecules. In addition to being relevant to high temperature chemical environments (e.g. plasmas and combustion), gas-phase experiments on metal containing molecules serve as the most direct link to a molecular-level theoretical model for catalysis. Catalysis (i.e. the addition of a small about of recoverable material to control the rate and direction of a chemical reaction) is critical to the petroleum and pharmaceutical industries as well as environmental remediation. Currently, the majority of catalytic materials are based on very expensive metals such as platinum (Pt), palladium (Pd), iridium (Ir,) rhenium (Re), and rhodium (Rh). For example, the catalyst used for converting linear hydrocarbon molecules (e.g. hexane) to cyclic molecules (e.g. cyclohexane) is a mixture of Pt and Re suspended on alumina. It enables straight chain alkanes to be converted into branched-chain alkanes, cyclohexanes and aromatic hydrocarbons which are used, amongst other things, to enhance the octane number of petrol. A second example is the heterogeneous catalysis used in automobile exhaust systems to: a) decrease nitrogen oxide; b) reduce carbon monoxide; and c) oxidize unburned hydrocarbons. The exhaust is vented through a high-surface area chamber lined with Pt, Pd, and Rh. For example, the carbon monoxide is catalytically converted to carbon dioxide by reaction with oxygen. The research results from this work have been published in readily accessible journals1-28. The ground and excited electronic state properties of small metal containing molecules that we determine were: a) electronic state distributions and lifetimes, b) vibrational frequencies, c) bond lengths and angles, d) hyperfine interactions, e) permanent electric dipole moments, mel, and f) magnetic dipoles, μm. In general terms, μel, gives insight into the charge distribution and mm into

  4. Single phase and two phase erosion corrosion in broilers of gas-cooled reactors

    International Nuclear Information System (INIS)

    Harrison, G.S.; Fountain, M.J.

    1988-01-01

    Erosion-corrosion is a phenomenon causing metal wastage in a variety of locations in water and water-steam circuits throughout the power generation industry. Erosion-corrosion can occur in a number of regions of the once-through boiler designs used in the later Magnox and AGR type of gas cooled nuclear reactor. This paper will consider two cases of erosion-corrosion damage (single and two phase) in once through boilers of gas cooled reactors and will describe the solutions that have been developed. The single phase problem is associated with erosion-corrosion damage of mild steel downstream of a boiler inlet flow control orifice. With metal loss rates of up to 1 mm/year at 150 deg. C and pH in the range 9.0-9.4 it was found that 5 μg/kg oxygen was sufficient to reduce erosion-corrosion rates to less than 0.02 mm/year. A combined oxygen-ammonia-hydrazine feedwater regime was developed and validated to eliminate oxygen carryover and hence give protection from stress corrosion in the austenitic section of the AGR once through boiler whilst still providing erosion-corrosion control. Two phase erosion-corrosion tube failures have occurred in the evaporator of the mild steel once through boilers of the later Magnox reactors operating at pressures in the range 35-40 bar. Rig studies have shown that amines dosed in the feedwater can provide a significant reduction in metal loss rates and a tube lifetime assessment technique has been developed to predict potential tube failure profiles in a fully operational boiler. The solutions identified for both problems have been successfully implemented and the experience obtained following implementation including any problems or other benefits arising from the introduction of the new regimes will be presented. Methods for monitoring and evaluating the efficiency of the solutions have been developed and the results from these exercises will also be discussed. Consideration will also be given to the similarities in the metal loss

  5. Single phase and two phase erosion corrosion in broilers of gas-cooled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, G S; Fountain, M J [Operational Engineering Division (Northern Area), Central Electricity Generating Board, Manchester (United Kingdom)

    1988-07-01

    Erosion-corrosion is a phenomenon causing metal wastage in a variety of locations in water and water-steam circuits throughout the power generation industry. Erosion-corrosion can occur in a number of regions of the once-through boiler designs used in the later Magnox and AGR type of gas cooled nuclear reactor. This paper will consider two cases of erosion-corrosion damage (single and two phase) in once through boilers of gas cooled reactors and will describe the solutions that have been developed. The single phase problem is associated with erosion-corrosion damage of mild steel downstream of a boiler inlet flow control orifice. With metal loss rates of up to 1 mm/year at 150 deg. C and pH in the range 9.0-9.4 it was found that 5 {mu}g/kg oxygen was sufficient to reduce erosion-corrosion rates to less than 0.02 mm/year. A combined oxygen-ammonia-hydrazine feedwater regime was developed and validated to eliminate oxygen carryover and hence give protection from stress corrosion in the austenitic section of the AGR once through boiler whilst still providing erosion-corrosion control. Two phase erosion-corrosion tube failures have occurred in the evaporator of the mild steel once through boilers of the later Magnox reactors operating at pressures in the range 35-40 bar. Rig studies have shown that amines dosed in the feedwater can provide a significant reduction in metal loss rates and a tube lifetime assessment technique has been developed to predict potential tube failure profiles in a fully operational boiler. The solutions identified for both problems have been successfully implemented and the experience obtained following implementation including any problems or other benefits arising from the introduction of the new regimes will be presented. Methods for monitoring and evaluating the efficiency of the solutions have been developed and the results from these exercises will also be discussed. Consideration will also be given to the similarities in the metal loss

  6. Initial Atomic Motion Immediately Following Femtosecond-Laser Excitation in Phase-Change Materials.

    Science.gov (United States)

    Matsubara, E; Okada, S; Ichitsubo, T; Kawaguchi, T; Hirata, A; Guan, P F; Tokuda, K; Tanimura, K; Matsunaga, T; Chen, M W; Yamada, N

    2016-09-23

    Despite the fact that phase-change materials are widely used for data storage, no consensus exists on the unique mechanism of their ultrafast phase change and its accompanied large and rapid optical change. By using the pump-probe observation method combining a femtosecond optical laser and an x-ray free-electron laser, we substantiate experimentally that, in both GeTe and Ge_{2}Sb_{2}Te_{5} crystals, rattling motion of mainly Ge atoms takes place with keeping the off-center position just after femtosecond-optical-laser irradiation, which eventually leads to a higher symmetry or disordered state. This very initial rattling motion in the undistorted lattice can be related to instantaneous optical change due to the loss of resonant bonding that characterizes GeTe-based phase change materials. Based on the amorphous structure derived by first-principles molecular dynamics simulation, we infer a plausible ultrafast amorphization mechanism via nonmelting.

  7. The central object R 136 in the gas nebula 30 Doradus - Structure, color, mass and excitation parameter

    Science.gov (United States)

    Feitzinger, J. V.; Schlosser, W.; Schmidt-Kaler, T.; Winkler, C.

    1980-04-01

    Photographic observations with the 3,6 m ESO and 0,61 m Bochum telescopes in different colours of the central part of the 30 Doradus Nebula are presented. The structure of the central object R 136 is studied by image analysis methods, i.e. digitalisation and contrast enhancement. The central object R 136 of the supergiant gas nebula 30 Doradus consists of three components; the main component covers an area of (0.7 pc)2. The components show a colour gradient, R 136a being much bluer than R 136c. This composite structure is seen in photographic IR, U and V likewise. A plot of the spectral intensity distribution from λ = 73 cm to 1550 Å of the central 2'.5 × 2'.5 region of 30 Doradus is given. The main contribution in the UV can be attributed to R 136. This object dominates the of the central part of 30 Doradus. It determines together with 16 other bright stars in the center the excitation parameter of the nebula. Its effective temperature lies between 50000 and 55000K and the tipper and lower mass values are 250 and 103 solar masses. The bolometric magnitude is brighter than -l4m. The inner structure of 30 Doradus can be explained as the result of the stellar-wind of R 136.

  8. Effects of aggregation on the excitation dynamics of LH2 from Thermochromatium tepidum in aqueous phase and in chromatophores.

    Science.gov (United States)

    Yang, Fan; Yu, Long-Jiang; Wang, Peng; Ai, Xi-Cheng; Wang, Zheng-Yu; Zhang, Jian-Ping

    2011-06-23

    We carried out femtosecond magic-angle and polarized pump-probe spectroscopies for the light-harvesting complex 2 (LH2) from Thermochromatium (Tch.) tepidum in aqueous phase and in chromatophores. To examine the effects of LH2 aggregation on the dynamics of excitation energy transfer, dominant monodispersed and aggregated LH2s were prepared by controlling the surfactant concentrations. The aqueous preparations solubilized with different concentrations of n-dodecyl-β-D-maltoside (DDM) show similar visible-to-near-infrared absorption spectra, but distinctively different aggregation states, as revealed by using dynamic light scattering. The B800 → B850 intra-LH2 energy transfer time was determined to be 1.3 ps for isolated LH2, which, upon aggregation in aqueous phase or clustering in chromatophores, shortened to 1.1 or 0.9 ps, respectively. The light-harvesting complex 1 (LH1) of this thermophilic purple sulfur bacterium contains bacteriochlorophyll a absorbing at 915 nm (B915), and the LH2(B850) → LH1(B915) intercomplex transfer time in chromatophores was found to be 6.6 ps. For chromatophores, a depolarization time of 21 ps was derived from the anisotropy kinetics of B850*, which is attributed to the migration of B850* excitation before being trapped by LH1. In addition, the B850* annihilation is accelerated upon LH2 aggregation in aqueous phase, but it is much less severe upon LH2 clustering in the intracytoplasmic membrane. These results are helpful in understanding the light-harvesting function of a bacterial photosynthetic membrane incorporating different types of antenna complexes.

  9. Detection methods for atoms and radicals in the gas phase

    Science.gov (United States)

    Hack, W.

    This report lists atoms and free radicals in the gas phase which are of interest for environmental and flame chemistry and have been detected directly. The detection methods which have been used are discussed with respect to their range of application, specificity and sensitivity. In table 1, detection methods for the five atoms of group IV (C, Si, Ge, Sn, Pb) and about 60 radicals containing at least one atom of group IV are summarized (CH, Cd, Cf, CC1, CBr, Cn, Cs, CSe, CH2, CD2, Chf, Cdf, CHC1, CHBr, CF2, CC12, CBr2, CFC1, CFBr, CH3, CD3, CF3, CH2F, CH2C1, CH2Br, CHF2, CHC12, CHBr2, Hco, Fco, CH30, CD30, CH2OH, CH3S, Nco, CH4N, CH302, CF302; C2, C2N, C2H, C20, C2HO, C2H3, C2F3, C2H5, C2HsO, C2H4OH, CH3CO, CD3CO, C2H3O, C2H502, CH3COO2, C2H4N, C2H6N, C3; Si, SiF, SiF2, SiO, SiC, Si2; Ge, GeC, GeO, GeF, GeF2, GeCl2, Sn, SnF, SnO, SnF2, Pb, PbF, PbF2, PbO, PbS). In table 2 detection methods for about 25 other atoms and 60 radicals are listed: (H, D, O, O2, Oh, Od, HO2, DO2, F, Ci, Br, I, Fo, Cio, BrO, Io, FO2, C1O2, Li, Na, K, Rb, Cs, N, N3, Nh, Nd, Nf, Nci, NBr, NH2, ND2, Nhd, Nhf, NF2, NC12, N2H3, No, NO2, NO3, Hno, Dno, P, Ph, Pd, Pf, Pci, PH2, PD2, PF2, Po, As, AsO, AsS, Sb, Bi, S, S2, Sh, Sd, Sf, SF2, So, Hso, Dso, Sn, Se, Te, Se2, SeH, SeD, SeF, SeO, SeS, SeN, TeH, TeO, Bh, BH2, Bo, Bn, B02, Cd, Hg, UF5). The tables also cite some recent kinetic applications of the various methods.

  10. Phase-locking phenomena and excitation of damped and driven nonlinear oscillators

    DEFF Research Database (Denmark)

    Shagalov, A.G.; Juul Rasmussen, Jens; Naulin, Volker

    2009-01-01

    Resonant phase-locking phenomena ('autoresonance') in the van der Pol Duffing oscillator forced by a small amplitude periodic driving with slowly varying frequency have been studied. We show that autoresonance occurs for oscillators with sufficiently small damping, when the system may have bi-stable...

  11. Investigation of the resistive phase in high power gas switching. Research and development report

    International Nuclear Information System (INIS)

    O'Rourke, R.C.

    1977-01-01

    A theoretical study was made of the resistive phase in high pressure gas switching with the regime of interest being (10 to 50) kV from (1J, 10ns, 100KHz) to (100J, 10μs, 1KHz). The resistive phase was examined as a function of applied field, gap spacing, inductance, gas type and pressure, and electrode material. The initiating and quenching phases as regards system performance (e.g., the jitter problem) were examined. The cooling and electrode debris removal effects of the vortex gas flow on the operating characteristics of the system were considered

  12. Optically-Based Diagnostics for Gas-Phase Laser Development

    Science.gov (United States)

    2010-08-01

    Laser (COIL), Electric Oxygen Iodine Laser (EOIL), Diode-Pumped Alkali Laser (DPAL), and Exciplex Alkali Laser (XPAL). The papers at this Symposium... exciplex -assisted absorption and laser-induced fluorescence, and multi-photon excitation of infrared atomic alkali transitions.11,12 In this paper... EXCIPLEX LASER SYSTEMS Proper review and discussion of the DPAL and XPAL laser systems can be found elsewhere,11,12 and in the paper by Carroll and

  13. Hot Gas TVC For Planetary Ascent Vehicle, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A Mars ascent vehicle (MAV) uses solid rocket motors to propel soil samples into orbit, but the motors cannot provide steering. Cold gas thrusters are used for...

  14. Advanced On Board Inert Gas Generation System (OBBIGS), Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Valcor Engineering Corporation proposes to develop an advanced On Board Inert Gas Generation System, OBIGGS, for aircraft fuel tank inerting to prevent hazardous...

  15. Rate for energy transfer from excited cyclohexane to nitrous oxide in the liquid phase

    International Nuclear Information System (INIS)

    Wada, T.; Hatano, Y.

    1975-01-01

    Pure liquid cyclohexane and cyclohexane solutions of nitrous oxide have been photolyzed at 163 nm. The quantum yield of the product hydrogen in the photolysis of pure cyclohexane is found to be 1.0. The addition of nitrous oxide results in the reduction in the yield of hydrogen and in the formation of nitrogen. The decrement of the hydrogen yield is approximately equal to the increment of the nitrogen yield. About 40 percent of the hydrogen yield in pure cyclohexane is found to be produced through a path which is not affected by the addition of nitrous oxide. The effect of the addition of nitrous oxide is attributed to energy transfer from excited cyclohexane to nitrous oxide with the rate constant of k = 1.0 x 10 11 M -1 sec -1 (at 15 0 C). This value is about a factor of 10 larger than that expected as for diffusion-controlled rate. A contribution of the energy transfer process to the formation of nitrogen in the radiolysis of cyclohexane solutions of nitrous oxide has also been discussed. (auth)

  16. Two-stage coal liquefaction without gas-phase hydrogen

    Science.gov (United States)

    Stephens, H.P.

    1986-06-05

    A process is provided for the production of a hydrogen-donor solvent useful in the liquefaction of coal, wherein the water-gas shift reaction is used to produce hydrogen while simultaneously hydrogenating a donor solvent. A process for the liquefaction of coal using said solvent is also provided. The process enables avoiding the use of a separate water-gas shift reactor as well as high pressure equipment for liquefaction. 3 tabs.

  17. Local gas- and liquid-phase measurements for air-water two-phase flows in a rectangular channel

    International Nuclear Information System (INIS)

    Zhou, X.; Sun, X.; Williams, M.; Fu, Y.; Liu, Y.

    2014-01-01

    Local gas- and liquid-phase measurements of various gas-liquid two-phase flows, including bubbly, cap-bubbly, slug, and churn-turbulent flows, were performed in an acrylic vertical channel with a rectangular cross section of 30 mm x 10 mm and height of 3.0 m. All the measurements were carried out at three measurement elevations along the flow channel, with z/D h = 9, 72, and 136, respectively, to study the flow development. The gas-phase velocity, void fraction, and bubble number frequency were measured using a double-sensor conductivity probe. A high-speed imaging system was utilized to perform the flow regime visualization and to provide additional quantitative information of the two-phase flow structure. An image processing scheme was developed to obtain the gas-phase velocity, void fraction, Sauter mean diameter, bubble number density, and interfacial area concentration. The liquid-phase velocity and turbulence measurements were conducted using a particle image velocimetry-planar laser-induced fluorescence (PIV-PLIF) system, which enables whole-field and high-resolution data acquisition. An optical phase separation method, which uses fluorescent particles and optical filtration technique, is adopted to extract the velocity information of the liquid phase. An image pre-processing scheme is imposed on the raw PIV images acquired to remove noises due to the presence of bubble residuals and optically distorted particles in the images captured by the PIV-PLIF system. Due to the better light access and less bubble distortion in the narrow rectangular channel, the PIV-PLIF system were able to perform reasonably well in flows of even higher void fractions as compared to the situations with circular pipe test sections. The flow conditions being studied covered various flow regime transitions, void fractions, and liquid-phase flow Reynolds numbers. The obtained experimental data can also be used to validate two-phase CFD results. (author)

  18. Beyond the Random Phase Approximation for the Electron Correlation Energy: The Importance of Single Excitations

    OpenAIRE

    Ren, Xinguo; Rinke, Patrick; Tkatchenko, Alexandre; Scheffler, Matthias

    2010-01-01

    The random-phase approximation (RPA) for the electron correlation energy, combined with the exact-exchange (EX) energy, represents the state-of-the-art exchange-correlation functional within density-functional theory. However, the standard RPA practice-evaluating both the EX and the RPA correlation energies using Kohn-Sham (KS) orbitals from local or semilocal exchange-correlation functionals-leads to a systematic underbinding of molecules and solids. Here we demonstrate that this behavior ca...

  19. Excited-state quantum phase transitions in systems with two degrees of freedom: Level density, level dynamics, thermal properties

    International Nuclear Information System (INIS)

    Stránský, Pavel; Macek, Michal; Cejnar, Pavel

    2014-01-01

    Quantum systems with a finite number of freedom degrees f develop robust singularities in the energy spectrum of excited states as the system’s size increases to infinity. We analyze the general form of these singularities for low f, particularly f=2, clarifying the relation to classical stationary points of the corresponding potential. Signatures in the smoothed energy dependence of the quantum state density and in the flow of energy levels with an arbitrary control parameter are described along with the relevant thermodynamical consequences. The general analysis is illustrated with specific examples of excited-state singularities accompanying the first-order quantum phase transition. -- Highlights: •ESQPTs found in infinite-size limit of systems with low numbers of freedom degrees f. •ESQPTs related to non-analytical evolutions of classical phase–space properties. •ESQPT signatures analyzed for general f, particularly f=2, extending known case f=1. •ESQPT signatures identified in smoothened density and flow of energy spectrum. •ESQPTs shown to induce a new type of thermodynamic anomalies

  20. Excited-state quantum phase transitions in systems with two degrees of freedom: II. Finite-size effects

    Energy Technology Data Exchange (ETDEWEB)

    Stránský, Pavel [Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague (Czech Republic); Macek, Michal [Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague (Czech Republic); Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, CT 06520-8120 (United States); Leviatan, Amiram [Racah Institute of Physics, The Hebrew University, 91904 Jerusalem (Israel); Cejnar, Pavel, E-mail: pavel.cejnar@mff.cuni.cz [Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague (Czech Republic)

    2015-05-15

    This article extends our previous analysis Stránský et al. (2014) of Excited-State Quantum Phase Transitions (ESQPTs) in systems of dimension two. We focus on the oscillatory component of the quantum state density in connection with ESQPT structures accompanying a first-order ground-state transition. It is shown that a separable (integrable) system can develop rather strong finite-size precursors of ESQPT expressed as singularities in the oscillatory component of the state density. The singularities originate in effectively 1-dimensional dynamics and in some cases appear in multiple replicas with increasing excitation energy. Using a specific model example, we demonstrate that these precursors are rather resistant to proliferation of chaotic dynamics. - Highlights: • Oscillatory components of state density and spectral flow studied near ESQPTs. • Enhanced finite-size precursors of ESQPT caused by fully/partly separable dynamics. • These precursors appear due to criticality of a subsystem with lower dimension. • Separability-induced finite-size effects disappear in case of fully chaotic dynamics.

  1. High-field magnetic phase transitions and spin excitations in magnetoelectric LiNiPO4

    DEFF Research Database (Denmark)

    Toft-Petersen, Rasmus; Jensen, Jens; Jensen, Thomas Bagger Stibius

    2011-01-01

    The magnetically ordered phases and spin dynamics of magnetoelectric LiNiPO4 have been studied in fields up to 17.3 T along the c axis. Using neutron diffraction, we show that a previously proposed linearly polarized incommensurate (IC) structure exists only for temperatures just below the Neel...... temperature T-N. The ordered IC structure at the lowest temperatures is shown instead to be an elliptically polarized canted spiral for fields larger than 12 T. The transition between the two IC phases is of second order and takes place about 2 K below T-N. For mu H-0 > 16 T and temperatures below 10 K......, the spiral structure is found to lock in to a period of five crystallographic unit cells along the b axis. Based on the neutron-diffraction data, combined with detailed magnetization measurements along all three crystallographic axes, we establish the magnetic phase diagrams for fields up to 17.3 T along c...

  2. Crystal-liquid-gas phase transitions and thermodynamic similarity

    CERN Document Server

    Skripov, Vladimir P; Schmelzer, Jurn W P

    2006-01-01

    Professor Skripov obtained worldwide recognition with his monograph ""Metastable liquids"", published in English by Wiley & Sons. Based upon this work and another monograph published only in Russia, this book investigates the behavior of melting line and the properties of the coexisting crystal and liquid phase of simple substances across a wide range of pressures, including metastable states of the coexisting phases. The authors derive new relations for the thermodynamic similarity for liquid-vapour phase transition, as well as describing solid-liquid, liquid-vapor and liquid-liquid phase tra

  3. Void fraction fluctuations in two-phase gas-liquid flow

    International Nuclear Information System (INIS)

    Ulbrich, R.

    1987-01-01

    Designs of the apparatus in which two-phase gas-liquid flow occurs are usually based on the mean value of parameters such as pressure drop and void fraction. The flow of two-phase mixtures generally presents a very complicated flow structure, both in terms of the unsteady formation on the interfacial area and in terms of the fluctuations of the velocity, pressure and other variables within the flow. When the gas void fraction is near 0 or 1 / bubble or dispersed flow regimes / then oscillations of void fraction are very small. The intermittent flow such as plug and slug/ froth is characterized by alternately flow portions of liquid and gas. It influences the change of void fractions in time. The results of experimental research of gas void fraction fluctuations in two-phase adiabatic gas-liquid flow in a vertical pipe are presented

  4. Two-phase gas bubble-liquid boundary layer flow along vertical and inclined surfaces

    International Nuclear Information System (INIS)

    Cheung, F.B.; Epstein, M.

    1985-01-01

    The behavior of a two-phase gas bubble liquid boundary layer along vertical and inclined porous surfaces with uniform gas injection is investigated experimentally and analytically. Using argon gas and water as the working fluids, a photographical study of the two-phase boundary layer flow has been performed for various angles of inclination ranging from 45 0 to 135 0 and gas injection rates ranging from 0.01 to 0.1 m/s. An integral method has been employed to solve the system of equations governing the two-phase motion. The effects of the gas injection rate and the angle of inclination on the growth of the boundary layer have been determined

  5. Random-phase-approximation approach to optical and magnetic excitations in the two-dimensional multiband Hubbard model

    International Nuclear Information System (INIS)

    Yonemitsu, K.; Bishop, A.R.

    1992-01-01

    As a convenient qualitative approach to strongly correlated electronic systems, an inhomogeneous Hartree-Fock plus random-phase approximation is applied to response functions for the two-dimensional multiband Hubbard model for cuprate superconductors. A comparison of the results with those obtained by exact diagonalization by Wagner, Hanke, and Scalapino [Phys. Rev. B 43, 10 517 (1991)] shows that overall structures in optical and magnetic particle-hole excitation spectra are well reproduced by this method. This approach is computationally simple, retains conceptual clarity, and can be calibrated by comparison with exact results on small systems. Most importantly, it is easily extended to larger systems and straightforward to incorporate additional terms in the Hamiltonian, such as electron-phonon interactions, which may play a crucial role in high-temperature superconductivity

  6. Enhanced Membrane System for Recovery of Water from Gas-Liquid Mixtures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Gas-Liquid separation is an acute microgravity problem. Existing devices use centrifugal motion on microporous membranes to separate the two phases. Centrifugal...

  7. Gas-phase water-mediated equilibrium between methylglyoxal and its geminal diol

    Science.gov (United States)

    Axson, Jessica L.; Takahashi, Kaito; De Haan, David O.; Vaida, Veronica

    2010-01-01

    In aqueous solution, aldehydes, and to a lesser extent ketones, hydrate to form geminal diols. We investigate the hydration of methylglyoxal (MG) in the gas phase, a process not previously considered to occur in water-restricted environments. In this study, we spectroscopically identified methylglyoxal diol (MGD) and obtained the gas-phase partial pressures of MG and MGD. These results, in conjunction with the relative humidity, were used to obtain the equilibrium constant, KP, for the water-mediated hydration of MG in the gas phase. The Gibbs free energy for this process, ΔG°, obtained as a result, suggests a larger than expected gas-phase diol concentration. This may have significant implications for understanding the role of organics in atmospheric chemistry. PMID:20142510

  8. Controlling the near-field excitation of nano-antennas with phase-change materials.

    Science.gov (United States)

    Kao, Tsung Sheng; Chen, Yi Guo; Hong, Ming Hui

    2013-01-01

    By utilizing the strongly induced plasmon coupling between discrete nano-antennas and quantitatively controlling the crystalline proportions of an underlying Ge2Sb2Te5 (GST) phase-change thin layer, we show that nanoscale light localizations in the immediate proximity of plasmonic nano-antennas can be spatially positioned. Isolated energy hot-spots at a subwavelength scale can be created and adjusted across the landscape of the plasmonic system at a step resolution of λ/20. These findings introduce a new approach for nano-circuitry, bio-assay addressing and imaging applications.

  9. Experimental and CFD investigation of gas phase freeboard combustion

    DEFF Research Database (Denmark)

    Andersen, Jimmy

    Reliable and accurate modeling capabilities for combustion systems are valuable tools for optimization of the combustion process. This work concerns primary precautions for reducing NO emissions, thereby abating the detrimental effects known as “acid rain”, and minimizing cost for flue gas...... treatment. The aim of this project is to provide validation data for Computational Fluid Dynamic (CFD) models relevant for grate firing combustion conditions. CFD modeling is a mathematical tool capable of predicting fluid flow, mixing and chemical reaction with thermal conversion and transport. Prediction......, but under well-defined conditions. Comprehensive experimental data for velocity field, temperatures, and gas composition are obtained from a 50 kW axisymmetric non-swirling natural gas fired combustion setup under two different settings. Ammonia is added to the combustion setup in order to simulate fuel...

  10. Gas phase ion/molecule reactions as studied by Fourier Transform Ion Cyclotron Resonance mass spectrometry

    International Nuclear Information System (INIS)

    Joergensen, S.I.

    1985-01-01

    The subject of this thesis is gas phase ion/molecule reactions as studied by Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometry (chapter 2 contains a short description of this method). Three chapters are mainly concerned with mechanistic aspects of gas phase ion/molecule reactions. An equally important aspect of the thesis is the stability and reactivity of α-thio carbanions, dipole stabilized carbanions and homoenolate anions, dealt with in the other four chapters. (Auth.)

  11. An atmospheric pressure flow reactor: Gas phase kinetics and mechanism in tropospheric conditions without wall effects

    Science.gov (United States)

    Koontz, Steven L.; Davis, Dennis D.; Hansen, Merrill

    1988-01-01

    A new type of gas phase flow reactor, designed to permit the study of gas phase reactions near 1 atm of pressure, is described. A general solution to the flow/diffusion/reaction equations describing reactor performance under pseudo-first-order kinetic conditions is presented along with a discussion of critical reactor parameters and reactor limitations. The results of numerical simulations of the reactions of ozone with monomethylhydrazine and hydrazine are discussed, and performance data from a prototype flow reactor are presented.

  12. Defect formation in fluoropolymer films at their condensation from a gas phase

    Science.gov (United States)

    Luchnikov, P. A.

    2018-01-01

    The questions of radiation defects, factors of influence of electronic high-frequency discharge plasma components on the molecular structure and properties of the fluoropolymer vacuum films synthesized on a substrate from a gas phase are considered. It is established that at sedimentation of fluoropolymer coverings from a gas phase in high-frequency discharge plasma in films there are radiation defects in molecular and supramolecular structure because of the influence of active plasma components which significantly influence their main properties.

  13. Two-phase xenon detector with gas amplification and electroluminescent signal detection

    International Nuclear Information System (INIS)

    Akimov, D.Yu.; Burenkov, A.A.; Grishkin, Yu.L.; Kovalenko, A.G.; Lebedenko, V.N.; Stekhanov, V.N.

    2008-01-01

    An optical technique for detecting ionization electrons produced during ionization of the liquid phase has been experimentally tested in two-phase (liquid-gas) xenon. The effects of gas and electroluminescent amplifications at the wire anode are simultaneously used for detection. This method allows construction of a supersensitive detector of small ionization signals-down to those corresponding to the detection of single electrons [ru

  14. A new method for determining gas phase heat of formation of aromatic energetic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Keshavarz, Mohammad H. [Department of Chemistry, Malek-ashtar University of Technology, Shahin-shahr P. O. Box 83145/115 (Iran); Tehrani, Masoud K. [Department of Physics, Malek-ashtar University of Technology, Shahin-shahr P. O. Box 83145/115 (Iran)

    2007-04-15

    A new correlation is introduced for desk calculation of gas phase heat of formation of aromatic energetic compounds that contain the elements of carbon, hydrogen, nitrogen and oxygen. Predicted gas phase heats of formation for 26 energetic compounds have a root mean square of deviation from experiment of 20.67 kJ/mol, which is in good agreement with respect to measured values of oxygen-lean and oxygen-rich aromatic energetic compounds. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  15. Molecular structure determination of cyclootane by ab initio and electron diffraction methods in the gas phase

    OpenAIRE

    De Almeida, Wagner B.

    2000-01-01

    The determination of the molecular structure of molecules is of fundamental importance in chemistry. X-rays and electron diffraction methods constitute in important tools for the elucidation of the molecular structure of systems in the solid state and gas phase, respectively. The use of quantum mechanical molecular orbital ab initio methods offer an alternative for conformational analysis studies. Comparison between theoretical results and those obtained experimentally in the gas phase can ma...

  16. Dynamic simulation of dispersed gas-liquid two-phase flow using a discrete bubble model.

    NARCIS (Netherlands)

    Delnoij, E.; Lammers, F.A.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    1997-01-01

    In this paper a detailed hydrodynamic model for gas-liquid two-phase flow will be presented. The model is based on a mixed Eulerian-Lagrangian approach and describes the time-dependent two-dimensional motion of small, spherical gas bubbles in a bubble column operating in the homogeneous regime. The

  17. DEMONSTRATION BULLETIN: GAS-PHASE CHEMICAL REDUCTION - ECO LOGIC INTERNATIONAL, INC.

    Science.gov (United States)

    The patented Eco Logic Process employs a gas-phase reduction reaction of hydrogen with organic and chlorinated organic compounds at elevated temperatures to convert aqueous and oily hazardous contaminants into a hydrocarbon-rich gas product. After passing through a scrubber, the ...

  18. Gas phase hydrogen peroxide production in atmospheric pressure glow discharges operating in He - H2O

    NARCIS (Netherlands)

    Vasko, C.A.; Veldhuizen, van E.M.; Bruggeman, P.J.

    2013-01-01

    The gas phase production of hydrogen peroxide (H2O2) in a RF atmospheric pressure glow discharge with helium and water vapour has been investigated as a function of the gas flow. It is shown that the production of H2O2 is through the recombination of two OH radicals in a three body collision and the

  19. Severe slugging in gas-liquid two-phase pipe flow

    NARCIS (Netherlands)

    Malekzadeh, R.

    2012-01-01

    transportation facilities. In an offshore oil and gas production facility, pipeline-riser systems are required to transport two-phase hydrocarbons from subsurface oil and gas wells to a central production platform. Severe slugs reaching several thousands pipe diameters may occur when transporting

  20. Formation mechanism of gas bubble superlattice in UMo metal fuels: Phase-field modeling investigation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Shenyang, E-mail: shenyang.hu@pnnl.gov; Burkes, Douglas E.; Lavender, Curt A.; Senor, David J.; Setyawan, Wahyu; Xu, Zhijie

    2016-10-15

    Nano-gas bubble superlattices are often observed in irradiated UMo nuclear fuels. However, the formation mechanism of gas bubble superlattices is not well understood. A number of physical processes may affect the gas bubble nucleation and growth; hence, the morphology of gas bubble microstructures including size and spatial distributions. In this work, a phase-field model integrating a first-passage Monte Carlo method to investigate the formation mechanism of gas bubble superlattices was developed. Six physical processes are taken into account in the model: 1) heterogeneous generation of gas atoms, vacancies, and interstitials informed from atomistic simulations; 2) one-dimensional (1-D) migration of interstitials; 3) irradiation-induced dissolution of gas atoms; 4) recombination between vacancies and interstitials; 5) elastic interaction; and 6) heterogeneous nucleation of gas bubbles. We found that the elastic interaction doesn’t cause the gas bubble alignment, and fast 1-D migration of interstitials along 〈110〉 directions in the body-centered cubic U matrix causes the gas bubble alignment along 〈110〉 directions. It implies that 1-D interstitial migration along [110] direction should be the primary mechanism of a fcc gas bubble superlattice which is observed in bcc UMo alloys. Simulations also show that fission rates, saturated gas concentration, and elastic interaction all affect the morphology of gas bubble microstructures.

  1. KINEMATICS AND EXCITATION OF THE RAM PRESSURE STRIPPED IONIZED GAS FILAMENTS IN THE COMA CLUSTER OF GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Michitoshi [Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Yagi, Masafumi; Komiyama, Yutaka; Kashikawa, Nobunari [Optical and Infrared Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Furusawa, Hisanori [Astronomical Data Center, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Hattori, Takashi [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' Ohoku Place, Hilo, HI 96720 (United States); Okamura, Sadanori, E-mail: yoshidam@hiroshima-u.ac.jp [Department of Astronomy, University of Tokyo, Tokyo 113-0033 (Japan)

    2012-04-10

    We present the results of deep imaging and spectroscopic observations of very extended ionized gas (EIG) around four member galaxies of the Coma Cluster of galaxies: RB 199, IC 4040, GMP 2923, and GMP 3071. The EIGs were serendipitously found in an H{alpha} narrowband imaging survey of the central region of the Coma Cluster. The relative radial velocities of the EIGs with respect to the systemic velocities of the parent galaxies from which they emanate increase almost monotonically with the distance from the nucleus of the respective galaxies, reaching {approx} - 400 to - 800 km s{sup -1} at around 40-80 kpc from the galaxies. The one-sided morphologies and the velocity fields of the EIGs are consistent with the predictions of numerical simulations of ram pressure stripping. We found a very low velocity filament (v{sub rel} {approx} -1300 km s{sup -1}) at the southeastern edge of the disk of IC 4040. Some bright compact knots in the EIGs of RB 199 and IC 4040 exhibit blue continuum and strong H{alpha} emission. The equivalent widths of the H{alpha} emission exceed 200 A and are greater than 1000 Angstrom-Sign for some knots. The emission-line intensity ratios of the knots are basically consistent with those of sub-solar abundance H II regions. These facts indicate that intensive star formation occurs in the knots. Some filaments, including the low-velocity filament of the IC 4040 EIG, exhibit shock-like emission-line spectra, suggesting that shock heating plays an important role in ionization and excitation of the EIGs.

  2. Biofilm structure and mass transfer in a gas phase trickle-bed biofilter.

    Science.gov (United States)

    Zhu, X; Suidan, M T; Alonso, C; Yu, T; Kim, B J; Kim, B R

    2001-01-01

    Mass transport phenomena occurring in the biofilms of gas phase trickle-bed biofilters are investigated in this study. The effect of biofilm structure on mass transfer mechanisms is examined using experimental observation from the operating of biofilters, microelectrode techniques and microscopic examination. Since the biofilms of biofilters used for waste gas treatment are not completely saturated with water, there is not a distinguishable liquid layer outside the biofilm. Results suggest that due to this characteristic, gas phase substrates (such as oxygen or volatile organic compounds) may not be limited by the aqueous phase because transport of the compound into the biofilm can occur directly through non-wetted areas. On the other hand, for substrates that are present only in the liquid phase, such as nitrate, the mass transfer limitation is more serious because of the limited liquid supply. Microscopic observations show that a layered structure with void spaces exists within the biofilm. Oxygen concentration distributions along the depth of the biofilms are examined using an oxygen microelectrode. Results indicate that there are some high dissolved oxygen zones inside the biofilm, which suggests the existence of passages for oxygen transfer into the deeper sections of the biofilm in a gas phase trickle-bed biofilter. Both the low gas-liquid mass transfer resistance and the resulting internal structure contribute to the high oxygen penetration within the biofilms in gas phase trickle-bed biofilters.

  3. Propagation characteristics of pulverized coal and gas two-phase flow during an outburst.

    Science.gov (United States)

    Zhou, Aitao; Wang, Kai; Fan, Lingpeng; Tao, Bo

    2017-01-01

    Coal and gas outbursts are dynamic failures that can involve the ejection of thousands tons of pulverized coal, as well as considerable volumes of gas, into a limited working space within a short period. The two-phase flow of gas and pulverized coal that occurs during an outburst can lead to fatalities and destroy underground equipment. This article examines the interaction mechanism between pulverized coal and gas flow. Based on the role of gas expansion energy in the development stage of outbursts, a numerical simulation method is proposed for investigating the propagation characteristics of the two-phase flow. This simulation method was verified by a shock tube experiment involving pulverized coal and gas flow. The experimental and simulated results both demonstrate that the instantaneous ejection of pulverized coal and gas flow can form outburst shock waves. These are attenuated along the propagation direction, and the volume fraction of pulverized coal in the two-phase flow has significant influence on attenuation of the outburst shock wave. As a whole, pulverized coal flow has a negative impact on gas flow, which makes a great loss of large amounts of initial energy, blocking the propagation of gas flow. According to comparison of numerical results for different roadway types, the attenuation effect of T-type roadways is best. In the propagation of shock wave, reflection and diffraction of shock wave interact through the complex roadway types.

  4. Phase transitions in vector quantization and neural gas

    NARCIS (Netherlands)

    Witoelar, Aree; Biehl, Michael

    The statistical physics of off-learning is applied to winner-takes-all (WTA) and rank-based vector quantization (VQ), including the neural gas (NG). The analysis is based on the limit of high training temperatures and the annealed approximation. The typical learning behavior is evaluated for systems

  5. Gas phase dispersion in a small rotary kiln

    International Nuclear Information System (INIS)

    Spencer, B.B.

    1981-07-01

    A study was made of nonideal flow of gas in a rotary kiln reactor. A rotating tube 0.165 m in diameter by 2.17 m long, with internal lifting flights, was operated at room temperature. Rotational speeds from 2.0 to 7.0 rpm, air flow rates from 0.351 to 4.178 m 3 /h, and solid contents of 0.0, 5.1, and 15.3% of tube volume were studied. Residence time distribution of the gas was measured by means of the pulse injection technique using a helium tracer. A model was developed based on dispersive flow that exchanges with a deadwater region. Two parameters, a dispersion number describing bulk gas flow and an interchange factor describing exchange between the flow region and the gas trapped in the solids bed, were sufficient to correlate the data, but these parameters are sensitive to experimental error. The model is applicable to analysis of other flow systems, such as packed beds

  6. Oriented xenon hydride molecules in the gas phase

    Czech Academy of Sciences Publication Activity Database

    Buck, U.; Fárník, Michal

    2006-01-01

    Roč. 25, č. 4 (2006), s. 583-612 ISSN 0144-235X Grant - others:Deutsche Forschungsgemeinschaft(DE) SFB 357 Institutional research plan: CEZ:AV0Z40400503 Keywords : photofragment translational spectroscopy * charge transfer molecules * low temperature matrices * neutral rare-gas Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.036, year: 2006

  7. Ceramic stationary gas turbine development. Final report, Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-09-01

    This report summarizes work performed by Solar Turbines Inc. and its subcontractors during the period September 25, 1992 through April 30, 1993. The objective of the work is to improve the performance of stationary gas turbines in cogeneration through implementation of selected ceramic components.

  8. Theoretical investigation of the long-lived metastable AlO{sup 2+} dication in gas phase

    Energy Technology Data Exchange (ETDEWEB)

    Sghaier, Onsi [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France); Abdallah, Hassan H. [Computational Nanotechnology Research Lab. CNRL, Salahaddin University, 44001 Erbil (Iraq); Department of Chemistry, College of Education, Salahaddin University, 44001 Erbil (Iraq); Abdullah, Hewa Y. [Computational Nanotechnology Research Lab. CNRL, Salahaddin University, 44001 Erbil (Iraq); Department of Physics, College of Education, Salahaddin University, 44001 Erbil (Iraq); Jaidane, Nejm Eddine [Laboratoire de Spectroscopie Atomique, Moléculaire et Applications – LSAMA, Université de Tunis, Tunis (Tunisia); Al Mogren, Muneerah Mogren [Chemistry Department, Faculty of Science, King Saud University, PO Box 2455, Riyadh 11451 (Saudi Arabia); Hochlaf, Majdi, E-mail: hochlaf@univ-mlv.fr [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France)

    2016-09-30

    Highlights: • Theoretical investigation of gas-phase molecular species AlO{sup 2+}. • Spectroscopic parameters of this dication in its electronic ground and exited states. • Theoretical double ionization spectrum of AlO. - Abstract: We report the results of a detailed theoretical study of the electronic ground and excited states of the gas-phase doubly charged ion AlO{sup 2+} using high-level ab initio computer calculations. Both standard and explicitly correlated methods were used to calculate their potential energy curves and spectroscopic parameters. These computations show that the ground state of AlO{sup 2+} is X{sup 2}Π. The internuclear equilibrium distance of AlO{sup 2+}(X{sup 2}Π) is computed 1.725 Å. We also deduced the adiabatic double ionization and charge stripping energies of AlO to be about 27.45 eV and 17.80 eV, respectively.

  9. Visualization of velocity field and phase distribution in gas-liquid two-phase flow by NMR imaging

    International Nuclear Information System (INIS)

    Matsui, G.; Monji, H.; Obata, J.

    2004-01-01

    NMR imaging has been applied in the field of fluid mechanics, mainly single phase flow, to visualize the instantaneous flow velocity field. In the present study, NMR imaging was used to visualize simultaneously both the instantaneous phase structure and velocity field of gas-liquid two-phase flow. Two methods of NMR imaging were applied. One is useful to visualize both the one component of liquid velocity and the phase distribution. This method was applied to horizontal two-phase flow and a bubble rising in stagnant oil. It was successful in obtaining some pictures of velocity field and phase distribution on the cross section of the pipe. The other is used to visualize a two-dimensional velocity field. This method was applied to a bubble rising in a stagnant water. The velocity field was visualized after and before the passage of a bubble at the measuring cross section. Furthermore, the distribution of liquid velocity was obtained. (author)

  10. Measurement of cross-sections for step-bystep excitation of inert gas atoms from metastable states by electron collisions

    International Nuclear Information System (INIS)

    Mityureva, A.A.; Penkin, N.P.; Smirnov, V.V.

    1989-01-01

    Excitation of argon atoms by electron collisions from metastable (MS) to high-lying states of inert gases (the so-called step-by-step excitation) is investigated. Formation of MS atoms m and their further step-by-step excitation up to k level is carried out by an electron beam with energy from 1 up to 40 eV. Time distribution of forming metastable and step-by-step electron collisions is used. The method used permits to measure the functions of step-by-step excitation and the absolute values of cross sections. Absolute values of cross-sections and functions of step-by-step excitation of some lines and argon levels are obtained

  11. CI, CII, and CO as tracers of gas phase carbon

    International Nuclear Information System (INIS)

    Keene, J.

    1990-01-01

    In the dense interstellar medium, we find that about 20 percent of the total carbon abundance is in the form of CO, about 3 percent in C I , and 100 percent in C II with uncertainties of factors of order 2. The abundance of other forms of gaseous carbon is negligible. CO is widespread throughout molecular clouds as is C I . C II has only been observed near bright star-formation regions so far because of its high excitation energy. Further from ultraviolet sources it may be less abundant. Altogether we have accounted for about 1/3 of the total carbon abundance associated with dense molecular clouds. Since the other gaseous forms are thought to have negligible abundances, the rest of the carbon is probably in solid form

  12. Liquid-gas phase transition and isospin fractionation in intermediate energy heavy ion collisions

    International Nuclear Information System (INIS)

    Xing Yongzhong; Liu Jianye; Guo Wenjun

    2004-01-01

    The liquid-gas phase transition in the heavy ion collisions and nuclear matter has been an important topic and got achievements, such as, based on the studies by H.Q. Song et al the critical temperature of liquid-gas phase transition enhances with increasing the mass of system and reduces as the increase of the neutron proton ratio of system. As authors know that both the liquid-gas phase transition and the isospin fractionation occur in the spinodal instability region at the nuclear density below the normal nuclear density. In particular, these two dynamical processes lead to the separation of nuclear matter into the liquid phase and gas phase. In this case to compare their dynamical behaviors is interested. The authors investigate the dependence of isospin fractionation degree on the mass and neutron proton ratio of system by using the isospin dependent quantum molecular dynamics model. The authors found that the degree of isospin fractionation (N/Z) n /(N/Z) imf decreases with increasing the mass of the system. This is just similar to the enhance of the critical temperature of liquid-gas phase transition T c as the increase of system mass. Because the enhance of T c is not favorable for the liquid-gas transition taking place, which reduces the isospin fractionation process and leads to decrease of (N/Z) n /(N/Z) imf . However the degree of isospin fractionation enhances with increasing the neutron proton ratio of the system. It is just corresponding to the reduce of T c of the liquid-gas phase transition as the increase of the isospin fractionation of the system. Because the reduce of T c enhances the liquid-gas phase transition process and also prompts the isospin fractionation process leading the increase of the isospin fractionation degree. To sum up, there are very similar dynamical behaviors for the degree of isospin fractionation and the critical temperature of the liquid-gas phase transition. So dynamical properties of the liquid-gas phase transition can

  13. Experimental and numerical investigation of gas phase freeboard combustion

    DEFF Research Database (Denmark)

    Andersen, J.; Jensen, Peter Arendt; Meyer, K.E.

    2009-01-01

    Experimental data for velocity field, temperatures, and gas composition have been obtained from a 50 kW axisymmetric non-swirling natural gas fired combustion setup under two different settings. The reactor was constructed to simulate the conditions in the freeboard of a grate-fired boiler...... but under well-defined conditions. The experimental results are compared to computational fluid dynamics (CFD) modeling predictions, using the eddy dissipation model (EDM) its well as the eddy dissipation concept (EDC). The use of EDC allows for implementation of more advanced combustion schemes; we have...... tested the four-step global mechanism by Jones and Lindstedt (Combust. Flame 1988, 73, 233-249), and the 16 species and 41 reaction skeletal mechanism by Yang and Pope (Combust. Flame 1998, 112 16-32). The CFD model captured the main features of the combustion process and flow patterns. The application...

  14. Experimental and numerical investigation of gas phase freeboard combustion

    DEFF Research Database (Denmark)

    Andersen, Jimmy; Jensen, Peter Arendt; Hvid, S.L.

    2009-01-01

    In part 1 of the present work (10.1021/ef900752a), experimental data and computational fluid dynamics (CFD) modeling predictions for velocity field, temperatures, and major species were compared fora 50 kW axisymmetric, non-swirling natural gas Fired combustion setup, constructed to simulate...... the conditions in the freeboard of it grate-fired boiler. Here, in part 2, the ability of CFD to predict volatile N oxidation to NO and N(2) is evaluated. Trace amounts of ammonia were added to the natural gas, and local measurements of NH(3) and NO in the reactor were compared to modeling predictions. Different...... modeling approaches, including global schemes and analytically reduced mechanisms, were tested in the CFD calculations. In addition, the simplified schemes were compared to reference calculations with a detailed mechanism under isothermal plug flow reactor conditions. While none of the global ammonia...

  15. Phases of a polar spin-1 Bose gas in a magnetic field

    International Nuclear Information System (INIS)

    Kis-Szabo, Krisztian; Szepfalusy, Peter; Szirmai, Gergely

    2007-01-01

    The two Bose-Einstein condensed phases of a polar spin-1 gas at nonzero magnetizations and temperatures are investigated. The Hugenholtz-Pines theorem is generalized to this system. Crossover to a quantum phase transition is also studied. Results are discussed in a mean field approximation

  16. Gas-phase polynuclear aromatic hydrocarbons (PAH) in vehicle exhaust: A method for collection and analysis

    International Nuclear Information System (INIS)

    Seigl, W.O.; Chladek, E.

    1990-01-01

    Gas-phase polynuclear aromatic hydrocarbons (PAH) are emitted at low levels in vehicle exhaust compared to other hydrocarbon emissions. A method has been developed involving the trapping of gas phase emissions on Tenax, a macrorecticular porous polymer, followed by thermal desorption onto a capillary gas chromatography column. Gas chromatography/mass spectrometry (GC/MS) was used for the chemical analysis. A detection limit of 0.05 ng was achieved for several gas-phase PAH. This high sensitivity enables the speciation and quantitation of gas-phase PAH collected from a dilution tube during standard driving (test) cycles. The method was demonstrated for the analysis of 9 PAH in the exhaust from a 1987 vehicle (with and without catalyst) during the hot start transient phase of the EPA urban dynamometer driving schedule. The PAH measured include naphthalene, 2-methyl- and 1-methylnaphthalene, biphenyl, fluorene, phenanthrene, anthracene, fluoranthene and pyrene. The four most abundant PAH observed are naphthalene, 2-methyl and 1-methylnaphthalene, and biphenyl, in that order

  17. Maxwell's Law Based Models for Liquid and Gas Phase Diffusivities in Variably-Saturated Soil

    DEFF Research Database (Denmark)

    Mamamoto, Shoichiro; Møldrup, Per; Kawamoto, Ken

    2012-01-01

    -s,D-l). Different percolation threshold terms adopted from recent studies for gas (D-s,D-g) and solute (D-s,D-l) diffusion were applied. For gas diffusion, epsilon(th) was a function of bulk density (total porosity), while for solute diffusion theta(th) was best described by volumetric content of finer soil...... particles (clay and organic matter), FINESvol. The resulting LIquid and GAs diffusivity and tortuosity (LIGA) models were tested against D-s,D-g and D-s,D-l data for differently-textured soils and performed well against the measured data across soil types. A sensitivity analysis using the new Maxwell's Law...... based LIGA models implied that the liquid phase but not the gaseous-phase tortuosity was controlled by soil type. The analyses also suggested very different pathways and fluid-phase connectivity for gas and solute diffusion in unsaturated soil...

  18. Analysis of volatile phase transport in soils using natural radon gas as a tracer

    International Nuclear Information System (INIS)

    Chen, C.; Thomas, D.M.

    1992-01-01

    We have conducted a field study of soil gas transport processes using radon gas as a naturally occurring tracer. The experiment monitored soil gas radon activity, soil moisture, and soil temperature at three depths in the shallow soil column; barometric pressure, rainfall and wind speed were monitored at the soil surface. Linear and multiple regression analysis of the data sets has shown that the gas phase radon activities under natural environmental conditions are influenced by soil moisture content, barometric pressure variations, soil temperature and soil structure. The effect of wind speed on subsurface radon activities under our field conditions has not been demonstrated

  19. Technology assessment of long distance liquid natural gas pipelines. Phase 8. Cold utilization and rural service

    Energy Technology Data Exchange (ETDEWEB)

    1977-02-01

    This phase of the investigation presents a summary of material relating to: (1) actual or potential applications for the very large refrigeration effects inherent in the vaporization of liquid natural gas; and (2) rural service gas supplies adjacent to the route of a trunk liquid natural gas line. A variety of concepts for cold utilization are discussed. The Canadian prospects for cold utilization include: electric power generation; oxygen production for integration with a coal gasification project; and the use of refrigeration stages in the petrochemical processing of natural gas, for example, ethane separation and processing to produce ethylene and ammonia.

  20. Performance analysis of a simple shunt and series compensated six-phase self-excited induction generator for stand-alone renewable energy generation

    International Nuclear Information System (INIS)

    Singh, G.K.; Kumar, A. Senthil; Saini, R.P.

    2011-01-01

    This paper describes a new generalized and efficient model for performance analysis of a six-phase self-excited induction generator (SPSEIG) with three capacitor excitation topologies; simple shunt, short shunt and long shunt. Mathematical model of SPSEIG is formulated using nodal admittance method based on graph theory. Attention is focused on the influence of the different capacitor connections on the generator overload and output power capabilities. The generator voltage with simple shunt excitation connection collapses when it is overloaded while with either the short shunt or long shunt excitation connection; generator is able to sustain the load at a lower operating voltage and larger load current. The matrix equation developed by nodal admittance method is solved by Genetic Algorithm (GA) technique to predetermine the steady-state performance of SPSEIG. The experimental and theoretical results are found to be in good agreement.

  1. CASCADER: An m-chain gas-phase radionuclide transport and fate model

    International Nuclear Information System (INIS)

    Cawlfield, D.E.; Been, K.B.; Emer, D.F.; Lindstrom, F.T.; Shott, G.J.

    1993-06-01

    Chemicals and radionuclides move either in the gas-phase, liquid-phase, or both phases in soils. They may be acted upon by either biological or abiotic processes through advection and/or diffusion. Furthermore, parent and daughter radionuclides may decay as they are transported in the soil. This is volume two to the CASCADER series, titled CASCADR8. It embodies the concepts presented in volume one of this series. To properly understand how the CASCADR8 model works, the reader should read volume one first. This volume presents the input and output file structure for CASCADR8, and a set of realistic scenarios for buried sources of radon gas

  2. CASCADER: An M-chain gas-phase radionuclide transport and fate model

    International Nuclear Information System (INIS)

    Cawlfield, D.E.; Emer, D.F.; Lindstrom, F.T.; Shott, G.J.

    1993-09-01

    Chemicals and radionuclides move either in the gas-phase, liquid-phase, or both phases in soils. They may be acted upon by either biological or abiotic processes through advection and/or dispersion. Additionally during the transport of parent and daughter radionuclides in soil, radionuclide decay may occur. This version of CASCADER called CASCADR9 starts with the concepts presented in volumes one and three of this series. For a proper understanding of how the model works, the reader should read volume one first. Also presented in this volume is a set of realistic scenarios for buried sources of radon gas, and the input and output file structure for CASCADER9

  3. The gas phase structure of α -pinene, a main biogenic volatile organic compound

    Science.gov (United States)

    Neeman, Elias M.; Avilés Moreno, Juan Ramón; Huet, Thérèse R.

    2017-12-01

    The gas phase structure of the bicyclic atmospheric aerosol precursor α-pinene was investigated employing a combination of quantum chemical calculation and Fourier transform microwave spectroscopy coupled to a supersonic jet expansion. The very weak rotational spectra of the parent species and all singly substituted 13C in natural abundance have been identified, from 2 to 20 GHz, and fitted to Watson's Hamiltonian model. The rotational constants were used together with geometrical parameters from density functional theory and ab initio calculations to determine the rs, r0, and rm(1 ) structures of the skeleton, without any structural assumption in the fit concerning the heavy atoms. The double C=C bond was found to belong to a quasiplanar skeleton structure containing 6 carbon atoms. Comparison with solid phase structure is reported. The significant differences of α-pinene in gas phase and other gas phase bicyclic monoterpene structures (β-pinene, nopinone, myrtenal, and bicyclo[3.1.1]heptane) are discussed.

  4. Characterizing the correlations between local phase fractions of gas-liquid two-phase flow with wire-mesh sensor.

    Science.gov (United States)

    Tan, C; Liu, W L; Dong, F

    2016-06-28

    Understanding of flow patterns and their transitions is significant to uncover the flow mechanics of two-phase flow. The local phase distribution and its fluctuations contain rich information regarding the flow structures. A wire-mesh sensor (WMS) was used to study the local phase fluctuations of horizontal gas-liquid two-phase flow, which was verified through comparing the reconstructed three-dimensional flow structure with photographs taken during the experiments. Each crossing point of the WMS is treated as a node, so the measurement on each node is the phase fraction in this local area. An undirected and unweighted flow pattern network was established based on connections that are formed by cross-correlating the time series of each node under different flow patterns. The structure of the flow pattern network reveals the relationship of the phase fluctuations at each node during flow pattern transition, which is then quantified by introducing the topological index of the complex network. The proposed analysis method using the WMS not only provides three-dimensional visualizations of the gas-liquid two-phase flow, but is also a thorough analysis for the structure of flow patterns and the characteristics of flow pattern transition. This article is part of the themed issue 'Supersensing through industrial process tomography'. © 2016 The Author(s).

  5. Topological phase transition in the quench dynamics of a one-dimensional Fermi gas

    OpenAIRE

    Wang, Pei; Yi, Wei; Xianlong, Gao

    2014-01-01

    We study the quench dynamics of a one-dimensional ultracold Fermi gas in an optical lattice potential with synthetic spin-orbit coupling. At equilibrium, the ground state of the system can undergo a topological phase transition and become a topological superfluid with Majorana edge states. As the interaction is quenched near the topological phase boundary, we identify an interesting dynamical phase transition of the quenched state in the long-time limit, characterized by an abrupt change of t...

  6. Phase diagram of a polarized Fermi gas across a Feshbach resonance in a potential trap

    International Nuclear Information System (INIS)

    Yi, W.; Duan, L.-M.

    2006-01-01

    We map out the detailed phase diagram of a trapped ultracold Fermi gas with population imbalance across a wide Feshbach resonance. We show that under the local density approximation, the properties of the atoms in any (anisotropic) harmonic traps are universally characterized by three dimensionless parameters: the normalized temperature, the dimensionless interaction strength, and the population imbalance. We then discuss the possible quantum phases in the trap, and quantitatively characterize their phase boundaries in various typical parameter regions

  7. Gas-phase Crystallization of Titanium Dioxide Nanoparticles

    International Nuclear Information System (INIS)

    Ahonen, P.P.; Moisala, A.; Tapper, U.; Brown, D.P.; Jokiniemi, J.K.; Kauppinen, E.I.

    2002-01-01

    We have investigated the development of crystal morphology and phase in ultrafine titanium dioxide particles. The particles were produced by a droplet-to-particle method starting from propanolic titanium tetraisopropoxide solution, and calcined in a vertical aerosol reactor in air. Mobility size classified 40-nm diameter particles were conveyed to the aerosol reactor to investigate particle size changes at 20-1200 deg. C with 5-1-s residence time. In addition, polydisperse particles were used to study morphology and phase formation by electron microscopy. According to differential mobility analysis, the particle diameter was reduced to 21-23-nm at 600 deg. C and above. Precursor decomposition occurred between 20 deg. C and 500 deg. C. The increased mobility particle size at 700 deg. C and above was observed to coincide with irregular particles at 700 deg. C and 800 deg. C and faceted particles between 900 deg. C and 1200 deg. C, according to transmission electron microscopy. The faceted anatase particles were observed to approach a minimized surface energy by forming {101} and {001} crystallographic surfaces. Anatase phase was observed at 500-1200 deg. C and above 600 deg. C the particles were single crystals. Indications of minor rutile formation were observed at 1200 deg. C. The relatively stable anatase phase vs. temperature is attributed to the defect free structure of the observed particles and a lack of crystal-crystal attachment points

  8. Flow measurement in two-phase (gas-liquid) systems

    International Nuclear Information System (INIS)

    Hewitt, G.F.; Whalley, P.B.

    1980-01-01

    The main methods of measuring mass flow and quality in gas-liquid flows in industrial situations are reviewed. These include gamma densitometry coupled with differential pressure devices such as crifice plates, turbine flow meters and drag screens. For each method the principle of operation, and the advantages and disadvantages, are given. Some further techniques which are currently being investigated and developed for routine use are also described briefly. Finally the detailed flow measurements possible on a particular flow pattern - annular flow - is examined. (author)

  9. Probing the Binding Interfaces of Protein Complexes Using Gas-Phase H/D Exchange Mass Spectrometry

    DEFF Research Database (Denmark)

    Mistarz, Ulrik H; Brown, Jeffery M; Haselmann, Kim F

    2016-01-01

    Fast gas-phase hydrogen/deuterium exchange mediated by ND3 gas and measured by mass spectrometry (gas-phase HDX-MS) is a largely unharnessed, fast, and sensitive method for probing primary- and higher-order polypeptide structure. Labeling of heteroatom-bound non-amide hydrogens in a sub-milliseco......Fast gas-phase hydrogen/deuterium exchange mediated by ND3 gas and measured by mass spectrometry (gas-phase HDX-MS) is a largely unharnessed, fast, and sensitive method for probing primary- and higher-order polypeptide structure. Labeling of heteroatom-bound non-amide hydrogens in a sub......-millisecond time span after electrospray ionization by ND3 gas can provide structural insights into protein conformers present in solution. Here, we have explored the use of gas-phase HDX-MS for probing the higher-order structure and binding interfaces of protein complexes originating from native solution...

  10. HERSCHEL FAR-INFRARED SPECTRAL-MAPPING OF ORION BN/KL OUTFLOWS: SPATIAL DISTRIBUTION OF EXCITED CO, H{sub 2}O, OH, O, AND C{sup +} IN SHOCKED GAS

    Energy Technology Data Exchange (ETDEWEB)

    Goicoechea, Javier R.; Cernicharo, José; Cuadrado, Sara; Etxaluze, Mireya [Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC). Sor Juana Ines de la Cruz 3, E-28049 Cantoblanco, Madrid (Spain); Chavarría, Luis [Centro de Astrobiología, CSIC-INTA, Ctra. de Torrejón a Ajalvir km 4, E-28850 Madrid (Spain); Neufeld, David A. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Vavrek, Roland [Herschel Science Center, ESA/ESAC, P.O. Box 78, Villanueva de la Cañada, E-28691 Madrid (Spain); Bergin, Edwin A. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Encrenaz, Pierre [LERMA, UMR 8112 du CNRS, Observatoire de Paris, École Normale Supérieure, F-75014 Paris (France); Melnick, Gary J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 66, Cambridge, MA 02138 (United States); Polehampton, Edward, E-mail: jr.goicoechea@icmm.csic.es [RAL Space, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom)

    2015-01-20

    We present ∼2' × 2' spectral-maps of Orion Becklin-Neugebauer/Kleinmann-Low (BN/KL) outflows taken with Herschel at ∼12'' resolution. For the first time in the far-IR domain, we spatially resolve the emission associated with the bright H{sub 2} shocked regions ''Peak 1'' and ''Peak 2'' from that of the hot core and ambient cloud. We analyze the ∼54-310 μm spectra taken with the PACS and SPIRE spectrometers. More than 100 lines are detected, most of them rotationally excited lines of {sup 12}CO (up to J = 48-47), H{sub 2}O, OH, {sup 13}CO, and HCN. Peaks 1/2 are characterized by a very high L(CO)/L {sub FIR} ≈ 5 × 10{sup –3} ratio and a plethora of far-IR H{sub 2}O emission lines. The high-J CO and OH lines are a factor of ≈2 brighter toward Peak 1 whereas several excited H{sub 2}O lines are ≲50% brighter toward Peak 2. Most of the CO column density arises from T {sub k} ∼ 200-500 K gas that we associate with low-velocity shocks that fail to sputter grain ice mantles and show a maximum gas-phase H{sub 2}O/CO ≲ 10{sup –2} abundance ratio. In addition, the very excited CO (J > 35) and H{sub 2}O lines reveal a hotter gas component (T {sub k} ∼ 2500 K) from faster (v {sub S} > 25 km s{sup –1}) shocks that are able to sputter the frozen-out H{sub 2}O and lead to high H{sub 2}O/CO ≳ 1 abundance ratios. The H{sub 2}O and OH luminosities cannot be reproduced by shock models that assume high (undepleted) abundances of atomic oxygen in the preshock gas and/or neglect the presence of UV radiation in the postshock gas. Although massive outflows are a common feature in other massive star-forming cores, Orion BN/KL seems more peculiar because of its higher molecular luminosities and strong outflows caused by a recent explosive event.

  11. Cold flame on Biofilm - Transport of Plasma Chemistry from Gas to Liquid Phase

    Science.gov (United States)

    Kong, Michael

    2014-10-01

    One of the most active and fastest growing fields in low-temperature plasma science today is biological effects of gas plasmas and their translation in many challenges of societal importance such as healthcare, environment, agriculture, and nanoscale fabrication and synthesis. Using medicine as an example, there are already three FDA-approved plasma-based surgical procedures for tissue ablation and blood coagulation and at least five phase-II clinical trials on plasma-assisted wound healing therapies. A key driver for realizing the immense application potential of near room-temperature ambient pressure gas plasmas, commonly known as cold atmospheric plasmas or CAP, is to build a sizeable interdisciplinary knowledge base with which to unravel, optimize, and indeed design how reactive plasma species interact with cells and their key components such as protein and DNA. Whilst a logical objective, it is a formidable challenge not least since existing knowledge of gas discharges is largely in the gas-phase and therefore not directly applicable to cell-containing matters that are covered by or embedded in liquid (e.g. biofluid). Here, we study plasma inactivation of biofilms, a jelly-like structure that bacteria use to protect themselves and a major source of antimicrobial resistance. As 60--90% of biofilm is made of water, we develop a holistic model incorporating physics and chemistry in the upstream CAP-generating region, a plasma-exit region as a buffer for as-phase transport, and a downstream liquid region bordering the gas buffer region. A special model is developed to account for rapid chemical reactions accompanied the transport of gas-phase plasma species through the gas-liquid interface and for liquid-phase chemical reactions. Numerical simulation is used to illustrate how key reactive oxygen species (ROS) are transported into the liquid, and this is supported with experimental data of both biofilm inactivation using plasmas and electron spin spectroscopy (ESR

  12. In Situ Environmental TEM in Imaging Gas and Liquid Phase Chemical Reactions for Materials Research.

    Science.gov (United States)

    Wu, Jianbo; Shan, Hao; Chen, Wenlong; Gu, Xin; Tao, Peng; Song, Chengyi; Shang, Wen; Deng, Tao

    2016-11-01

    Gas and liquid phase chemical reactions cover a broad range of research areas in materials science and engineering, including the synthesis of nanomaterials and application of nanomaterials, for example, in the areas of sensing, energy storage and conversion, catalysis, and bio-related applications. Environmental transmission electron microscopy (ETEM) provides a unique opportunity for monitoring gas and liquid phase reactions because it enables the observation of those reactions at the ultra-high spatial resolution, which is not achievable through other techniques. Here, the fundamental science and technology developments of gas and liquid phase TEM that facilitate the mechanistic study of the gas and liquid phase chemical reactions are discussed. Combined with other characterization tools integrated in TEM, unprecedented material behaviors and reaction mechanisms are observed through the use of the in situ gas and liquid phase TEM. These observations and also the recent applications in this emerging area are described. The current challenges in the imaging process are also discussed, including the imaging speed, imaging resolution, and data management. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Gas-phase chemistry of element 114, flerovium

    Directory of Open Access Journals (Sweden)

    Yakushev Alexander

    2016-01-01

    Full Text Available Element 114 was discovered in 2000 by the Dubna-Livermore collaboration, and in 2012 it was named flerovium. It belongs to the group 14 of the periodic table of elements. A strong relativistic stabilisation of the valence shell 7s27p21/2 is expected due to the orbital splitting and the contraction not only of the 7s2 but also of the spherical 7p21/2 closed subshell, resulting in the enhanced volatility and inertness. Flerovium was studied chemically by gas-solid chromatography upon its adsorption on a gold surface. Two experimental results on Fl chemistry have been published so far. Based on observation of three atoms, a weak interaction of flerovium with gold was suggested in the first study. Authors of the second study concluded on the metallic character after the observation of two Fl atoms deposited on gold at room temperature.

  14. Fixing arsenic contained in a gas phase using solid hematite

    International Nuclear Information System (INIS)

    Balladares, E.; Gonzalez, A.; Rarra, R.; Sanchez, M.

    2004-01-01

    Feasibility to obtain ferric arsenate starting from arsenic containing gas in contact with Fe 3 O 3 has been studied. Thermodynamic stability of the system Fe-As-O was analysed in order to verify conditions to form Fe x As y O z type compounds. Experiments were made using a hematite sample suspended in a thermogravimetric device. As 4 O 6 was generated starting from solid As 2 O 3 which was circulating through the iron oxide. Final samples were analysed chemically and by means of DRX, verifying the formation of FeAsO 4 , FeAsO 4 .2h 2 O and FeAsO 4 .(H 2 O) 2 in small quantities. Tests in porous bed and pellets were carried out, studying the effect of: porosity, temperature and oxygen potential. The largest conversion obtained was 10% at 800 degree centigrade, pO 2 =50% and porosity=0.883. (Author) 9 refs

  15. Modelling gas migration in compacted bentonite: GAMBIT Club Phase 2. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Swift, B.T.; Hoch, A.R.; Rodwell, W.R. [AEA Technology (United Kingdom)

    2001-01-01

    This report describes the second phase of a programme of work to develop a computational model of gas migration through highly compacted bentonite. Experimental data that have appeared since the earlier report are reviewed for the additional information they might provide on the mechanism of gas migration in bentonite. Experiments carried out by Horseman and Harrigton (British Geological Survey) continued to provide the main data sets used in model evaluation. The earlier work (POSIVA Report 98-08) had resulted in a preliminary model of gas migration whose main features are gas invasion by microcrack propagation, and dilation of the pathways formed with increasing gas pressure. New work was carried out to further explore the capabilities of this model. In addition, a feature was added to the model to simulate gas pathway creation by water displacement rather than crack propagation. The development of a new alternative gas migration model is described. This is based on a volume-averaged representation of gas migration rather than on a description of flow in discrete pathways. Evaluation of this alternative model showed that it can produce similar agreement with experimental results to the other models examined. The implications of flow geometry, confining conditions and flow boundary conditions on gas migration behaviour in bentonite are reviewed. Proposals are made for the development of the new model into a tool for simulating gas migration through a bentonite buffer around a waste canister, and for possible enhancements to the model that might remove some of its currently perceived deficiencies. (orig.)

  16. Modelling gas migration in compacted bentonite: gambit club phase 3. Final report

    International Nuclear Information System (INIS)

    Hoch, A.R.; Cliffe, K.A.; Swift, B.T.; Rodwell, W.R.

    2004-04-01

    This report describes the third phase of a programme of work to develop a computational model of gas migration through highly compacted water-saturated bentonite. One difficulty with this endeavour is the definitive determination of the mechanism of the gas migration from the available experimental data. The report contains a brief review of the experimental data and their interpretation. The model development work reported involves the investigation of two ways of enhancing a model proposed in the previous phase of the programme. This model was based on the concept that gas migration pathways were created by consolidating the clay fabric by application of gas pressure to create porosity through which the gas could flow. The two developments of this model that are separately explored in this work are: (a) The incorporation of a proper treatment of the stress-strain behaviour of the clay in (b) response to gas migration. The previous model had only considered stress effects through simple volume changes to the clay fabric. The inclusion of a dual-porosity feature into the model in an attempt to address the role that the clay fabric might play in gas migration through the clay, in particular the role that pre-existing interstack voids might have in gas migration. The consideration of hysteresis effects was also included in this study. As in previous GAMBIT Club work, the models are tested against the results of laboratory experiments. (orig.)

  17. The α-particle excited scintillation response of YAG:Ce thin films grown by liquid phase epitaxy

    International Nuclear Information System (INIS)

    Prusa, Petr; Nikl, Martin; Mares, Jiri A.; Nitsch, Karel; Beitlerova, Alena; Kucera, Miroslav

    2009-01-01

    Y 3 Al 5 O 12 :Ce (YAG:Ce) thin films were grown from PbO-,BaO-, and MoO 3 -based fluxes using the liquid phase epitaxy (LPE) method. Photoelectron yield, its time dependence within 0.5-10 μs shaping time, and energy resolution of these samples were measured under α-particle excitation. For comparison a sample of the Czochralski grown bulk YAG:Ce single crystal was measured as well. Photoelectron yield values of samples grown from the BaO-based flux were found superior to other LPE films and comparable with that of the bulk single crystal. The same is valid also for the time dependence of photoelectron yield. Obtained results are discussed taking into account the influence of the flux and technology used. Additionally, α particle energy deposition in very thin films is modelled and discussed. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Search for 2νββ excited state transitions and HPGe characterization for surface events in GERDA phase II

    Energy Technology Data Exchange (ETDEWEB)

    Lehnert, Bjoern

    2016-03-01

    The search for the neutrinoless double beta (0νββ) decay is one of the most active fields in modern particle physics. This process is not allowed within the Standard Model and its observation would imply lepton number violation and would lead to the Majorana nature of neutrinos. The experimentally observed quantity is the half-life of the decay, which can be connected to the effective Majorana neutrino mass via nuclear matrix elements. The latter can only be determined theoretically and are currently affected by large uncertainties. To reduce these uncertainties one can investigate the well established two-neutrino double beta (2νββ) decay into the ground and excited states of the daughter isotope. These similar processes are allowed within the Standard Model. In this dissertation, the search for 2νββ decays into excited states is performed in {sup 110}Pd, {sup 102}Pd and {sup 76}Ge. Three gamma spectroscopy setups at the Felsenkeller (Germany), HADES (Belgium) and LNGS (Italy) underground laboratories are used to search for the transitions in {sup 110}Pd and {sup 102}Pd. No signal is observed leading to lower half-live bounds (90% C.I.) of 2.9 . 10{sup 20} yr, 3.9 . 10{sup 20} yr and 2.9 . 10{sup 20} yr for the 0/2νββ 2{sup +}{sub 1}, 0{sup +}{sub 1} and 2{sup +}{sub 2} transitions in {sup 110}Pd and 7.9 . 10{sup 18} yr, 9.2 . 10{sup 18} yr and 1.5 . 10{sup 19} yr for the 0/2νββ 2{sup +}{sub 1}, 0{sup +}{sub 1} and 2{sup +}{sub 2} transitions in {sup 102}Pd, respectively. This is a factor of 1.3 to 3 improvement compared to previous limits. The data of Phase I (Nov 2011 - May 2013) of the 0νββ decay experiment GERDA at LNGS is used to search for excited state transitions in {sup 76}Ge. The analysis is based on coincidences between two detectors and finds no signal. Lower half-life limits (90 % C.L.) of 1.6.10{sup 23} yr, 3.7.10{sup 23} yr and 2.3.10{sup 23} yr are obtained for the 2νββ 2{sup +}{sub 1}, 0{sup +}{sub 1} and 2{sup +}{sub 2

  19. Droplet model of pyrocarbon deposition from the gas phase. [HTGR

    Energy Technology Data Exchange (ETDEWEB)

    Linke, J; Koizlik, K; Luhleich, H; Nickel, H

    1975-01-15

    Based on extensive earlier work a model has been developed to describe the formation of carbon by pyrolysis of gaseous hydrocarbons. One of the central statements of this model is the assumption of the existence of a quasi liquid carbon phase during deposition process.This model is described and is discussed as are the consequences for the material properties and structural parameters which arise from it. To review the droplet model, statically deposited pyrocarbon is examined by characterization methods suitable to analyze just these structural parameters.The results prove the model conceptions to be realistic.

  20. Market chances for innovative natural gas applications. The determination of market potential by means of a phase model

    International Nuclear Information System (INIS)

    Hoelen, Q.E.J.J.M.; Klootwijk, M.

    2000-01-01

    Innovative applications of natural gas can increase the sale of natural gas, support energy companies in the development of commercial activities, and contribute to energy efficiency measures. The Dutch natural gas trading company Gasunie supports those developments by investigating the market potential of innovative gas appliances. Use is made of the so-called Phase Model for Market Introduction, developed by Kea Consult

  1. Vibrational energy transfer in gas phase water and ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Hovis, F.E. Jr.

    1979-09-01

    The V ..-->.. T, R relaxation rate for NH/sub 3/ (..nu../sub 2/) was studied from 198/sup 0/K to 398/sup 0/K by the method of laser-excited vibrational fluorescence. The self-deactivation rate constant decreases from 2.4 ..mu..sec torr/sup -1/ at 198/sup 0/K to 0.65 ..mu..sec/sup -1/ torr/sup -1/ at 398/sup 0/K. The rate constants for deactivation by He, Ar, N/sub 2/, and O/sub 2/ are much smaller and show a weak temperature dependence in the opposite direction. The vibrational relaxation rates of the coupled ..nu../sub 1/, ..nu../sub 3/ stretching level manifold and of the 2..nu../sub 2/ bending level in H/sub 2//sup 18/O was studied from 250/sup 0/K to 400/sup 0/K using th same method as for NH/sub 3/. The ..nu../sub 1/, ..nu../sub 3/ self-deactivation rate goes from 1.4 ..mu..sec/sup -1/ torr/sup -1/ at 250/sup 0/K to 0.48 ..mu..sec-/sup 1/ torr-/sup 1/ at 400/sup 0/K. For 2..nu../sub 2/ it goes from 4.5 ..mu..sec-/sup 1/ torr to 1.9 ..mu..sec/sup -1/ torr/sup -1/. The temperature dependence of the deactivation of both levels by He and Ar is much weaker and the rates are several hundred times slower. Deactivation of ..nu../sub 1/, ..nu../sub 3/ by N/sub 2/, O/sub 2/, and CO/sub 2/ is measured only at 293/sup 0/K. N/sub 2/ and O/sub 2/ deactivate ..nu../sub 1/, ..nu../sub 3/ about 5 and CO/sub 2/ about 50 times faster than He or Ar.

  2. Radical Reactions in the Gas Phase: Recent Development and Application in Biomolecules

    Directory of Open Access Journals (Sweden)

    Yang Gao

    2014-01-01

    Full Text Available This review summarizes recent literature describing the use of gas phase radical reactions for structural characterization of complex biomolecules other than peptides. Specifically, chemical derivatization, in-source chemical reaction, and gas phase ion/ion reactions have been demonstrated as effective ways to generate radical precursor ions that yield structural informative fragments complementary to those from conventional collision-induced dissociation (CID. Radical driven dissociation has been applied to a variety of biomolecules including peptides, nucleic acids, carbohydrates, and phospholipids. The majority of the molecules discussed in this review see limited fragmentation from conventional CID, and the gas phase radical reactions open up completely new dissociation channels for these molecules and therefore yield high fidelity confirmation of the structures of the target molecules. Due to the extensively studied peptide fragmentation, this review focuses only on nonpeptide biomolecules such as nucleic acids, carbohydrates, and phospholipids.

  3. Measurement of pressure fluctuation in gas-liquid two-phase vortex street

    International Nuclear Information System (INIS)

    Sun Zhiqiang; Sang Wenhui; Zhang Hongjian

    2009-01-01

    The pressure fluctuation in the wake is an important parameter to characterize the shedding process of gas-liquid two-phase Karman vortex street. This paper investigated such pressure fluctuations in a horizontal pipe using air and water as the tested fluid media. The dynamic signal representing the pressure fluctuation was acquired by the duct-wall differential pressure method. Results show that in the wake of the gas-liquid two-phase Karman vortex street, the frequency of the pressure fluctuation is linear with the Reynolds number when the volume void fraction is within the range of 18%. Moreover, the mean amplitude of the pressure fluctuation decreases with the volume void fraction, and the mean amplitude is larger at higher water flowrates under the same volume void fraction. These findings contribute to an in-depth understanding of the gas-liquid two-phase Karman vortex street.

  4. Molecular structure determination of cyclooctane by Ab Initio and electron diffraction methods in the gas phase

    International Nuclear Information System (INIS)

    Almeida, Wagner B. de

    2000-01-01

    The determination of the molecular structure of molecules is of fundamental importance in chemistry. X-rays and electron diffraction methods constitute in important tools for the elucidation of the molecular structure of systems in the solid state and gas phase, respectively. The use of quantum mechanical molecular orbital ab initio methods offer an alternative for conformational analysis studies. Comparison between theoretical results and those obtained experimentally in the gas phase can make a significant contribution for an unambiguous determination of the geometrical parameters. In this article the determination for an unambiguous determination of the geometrical parameters. In this article the determination of the molecular structure of the cyclooctane molecule by electron diffraction in the gas phase an initio calculations will be addressed, providing an example of a comparative analysis of theoretical and experimental predictions. (author)

  5. Metal-Organic Framework Thin Films as Stationary Phases in Microfabricated Gas-Chromatography Columns.

    Energy Technology Data Exchange (ETDEWEB)

    Read, Douglas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sillerud, Colin Halliday [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    The overarching goal of this project is to integrate Sandia's microfabricated gas-chromatography ( GC) columns with a stationary phase material that is capable of retaining high-volatility chemicals and permanent gases. The successful integration of such a material with GCs would dramatically expand the repertoire of detectable compounds for Sandia's various microanalysis systems. One such promising class of candidate materials is metal-organic frameworks (MOFs). In this report we detail our methods for controlled deposition of HKUST-1 MOF stationary phases within GC columns. We demonstrate: the chromatographic separation of natural gas; a method for determining MOF film thickness from chromatography alone; and the first-reported GC x GC separation of natural gas -- in general -- let alone for two disparate MOF stationary phases. In addition we determine the fundamental thermodynamic constant for mass sorption, the partition coefficient, for HKUST-1 and several light hydrocarbons and select toxic industrial chemicals.

  6. The Stability of CI02 as a Product of Gas Phase Decontamination Treatments

    International Nuclear Information System (INIS)

    Simmons, D. W.

    1994-01-01

    The gas phase decontamination project is investigating the use of chlorine trifluoride (ClF 3 ) to fluorinate nonvolatile uranium deposits to produce uranium hexafluoride (UF 6 ) gas. The potential existence of chlorine dioxide (ClO 2 ) during gas phase decontamination with ClF 3 has been the subject of recent safety discussions. Some of the laboratory data collected during feasibility studies of the gas phase process has been evaluated for the presence of ClO 2 in the product gas stream. The preliminary evidence to date can be summarized as follows: (1) ClO 2 was not detected in the flow loop in the absence of ClF 3 ; (2) ClO 2 was not detected in the static reactors in the absence of both ClF 3 and ClF; and (3) ClO 2 was detected in a static reactor in the absence of all fluorinating gases. The experimental evidence suggests that ClO 2 will not exist in the presence of ClF 3 , ClF, or UF 6 . The data analyzed to date is insufficient to determine the stability of ClO 2 in the presence of ClO 2 F. Thermodynamic calculations of the ClF 3 + H 2 O system support the experimental evidence, and suggest that ClO 2 will not exist in the presence of ClO 2 F. Additional experimental efforts are needed to provide a better understanding of the gas phase ClF 3 treatments and the product gases. However, preliminary evidence to date suggests that ClO 2 should not be present as a product during the normal operations of the gas phase decontamination project

  7. The Stability of CI02 as a Product of Gas Phase Decontamination Treatments

    Energy Technology Data Exchange (ETDEWEB)

    D. W. Simmons

    1994-09-01

    The gas phase decontamination project is investigating the use of chlorine trifluoride (ClF{sub 3}) to fluorinate nonvolatile uranium deposits to produce uranium hexafluoride (UF{sub 6}) gas. The potential existence of chlorine dioxide (ClO{sub 2}) during gas phase decontamination with ClF{sub 3} has been the subject of recent safety discussions. Some of the laboratory data collected during feasibility studies of the gas phase process has been evaluated for the presence of ClO{sub 2} in the product gas stream. The preliminary evidence to date can be summarized as follows: (1) ClO{sub 2} was not detected in the flow loop in the absence of ClF{sub 3}; (2) ClO{sub 2} was not detected in the static reactors in the absence of both ClF{sub 3} and ClF; and (3) ClO{sub 2} was detected in a static reactor in the absence of all fluorinating gases. The experimental evidence suggests that ClO{sub 2} will not exist in the presence of ClF{sub 3}, ClF, or UF{sub 6}. The data analyzed to date is insufficient to determine the stability of ClO{sub 2} in the presence of ClO{sub 2}F. Thermodynamic calculations of the ClF{sub 3} + H{sub 2}O system support the experimental evidence, and suggest that ClO{sub 2} will not exist in the presence of ClO{sub 2}F. Additional experimental efforts are needed to provide a better understanding of the gas phase ClF{sub 3} treatments and the product gases. However, preliminary evidence to date suggests that ClO{sub 2} should not be present as a product during the normal operations of the gas phase decontamination project.

  8. Liquid-gas phase transition in asymmetric nuclear matter at finite temperature

    International Nuclear Information System (INIS)

    Maruyama, Toshiki; Tatsumi, Toshitaka; Chiba, Satoshi

    2010-01-01

    Liquid-gas phase transition is discussed in warm asymmetric nuclear matter. Some peculiar features are figured out from the viewpoint of the basic thermodynamics about the phase equilibrium. We treat the mixed phase of the binary system based on the Gibbs conditions. When the Coulomb interaction is included, the mixed phase is no more uniform and the sequence of the pasta structures appears. Comparing the results with those given by the simple bulk calculation without the Coulomb interaction, we extract specific features of the pasta structures at finite temperature.

  9. Liquid-gas phase transition in asymmetric nuclear matter at finite temperature

    Science.gov (United States)

    Maruyama, Toshiki; Tatsumi, Toshitaka; Chiba, Satoshi

    2010-03-01

    Liquid-gas phase transition is discussed in warm asymmetric nuclear matter. Some peculiar features are figured out from the viewpoint of the basic thermodynamics about the phase equilibrium. We treat the mixed phase of the binary system based on the Gibbs conditions. When the Coulomb interaction is included, the mixed phase is no more uniform and the sequence of the pasta structures appears. Comparing the results with those given by the simple bulk calculation without the Coulomb interaction, we extract specific features of the pasta structures at finite temperature.

  10. Single-phase and two-phase gas-liquid turbulent mixing between subchannels in a simulated rod bundle

    International Nuclear Information System (INIS)

    Sadatomi, Michio; Kawahara, Akimaro; Sato, Yoshifusa; Tomino, Takayoshi.

    1996-01-01

    This study is concerned with turbulent mixing which is one of the three mechanisms of cross flows between subchannels in a nuclear fuel rod bundle. The channel used in this experiments was a vertical simulated rod bundle having two subchannels connected through 1 to 3 gaps between two rods and/or rod and channel wall. The number of the gaps was changed to investigate the effect of the number on the turbulent mixing. Turbulent mixing rates of air and water and fluctuations of pressure difference between the subchannels were measured for single-phase and two-phase gas-liquid flows under hydrodynamic equilibrium flow conditions. It has been confirmed that the turbulent mixing rate is affected strongly by the fluctuations especially for liquid phase in two-phase slug or churn flow. (author)

  11. Gas adsorption/absorption heat switch, phase 1

    Science.gov (United States)

    Chan, C. K.

    1987-01-01

    The service life and/or reliability of far-infrared sensors on surveillance satellites is presently limited by the cryocooler. The life and/or reliability, however, can be extended by using redundant cryocoolers. To reduce parasitic heat leak, each stage of the inactive redundant cryocooler must be thermally isolated from the optical system, while each stage of the active cryocooler must be thermally connected to the system. The thermal break or the thermal contact can be controlled by heat switches. Among different physical mechanisms for heat switching, mechanically activated heat switches tend to have low reliability and, furthermore, require a large contact force. Magnetoresistive heat switches are, except at very low temperatures, of very low efficiency. Heat switches operated by the heat pipe principle usually require a long response time. A sealed gas gap heat switch operated by an adsorption pump has no mechanical motion and should provide the reliability and long lifetime required in long-term space missions. Another potential application of a heat switch is the thermal isolation of the optical plane during decontamination.

  12. Synthesis gas demonstration plant program, Phase I. Site confirmation report

    Energy Technology Data Exchange (ETDEWEB)

    1978-12-01

    With few reservations, the Baskett, Kentucky site exhibits the necessary characteristics to suggest compatibility with the proposed Synthesis Gas Demonstration Plant Project. An evaluation of a broad range of technical disciplinary criteria in consideration of presently available information indicated generally favorable conditions or, at least, conditions which could be feasibly accommodated in project design. The proximity of the Baskett site to market areas and sources of raw materials as well as a variety of transportation facilities suggests an overall favorable impact on Project economic feasibility. Two aspects of environmental engineering, however, have been identified as areas where the completion or continuation of current studies are required before removing all conditions on site suitability. The first aspect involves the current contradictory status of existing land use and planning ordinances in the site area. Additional investigation of the legality of, and local attitudes toward, these present plans is warranted. Secondly, terrestrial and aquatic surveys of plant and animal life species in the site area must be completed on a seasonal basis to confirm the preliminary conclusion that no exclusionary conditions exist.

  13. Influence analysis of electronically and vibrationally excited particles on the ignition of methane and hydrogen under the conditions of a gas turbine engine

    Science.gov (United States)

    Deminskii, M. A.; Konina, K. M.; Potapkin, B. V.

    2018-03-01

    The vibronic and electronic energy relaxation phenomena in the specific conditions of a gas turbine engine were investigated in this paper. The plasma-chemical mechanism has been augmented with the results of recent investigations of the processes that involve electronically and vibrationally excited species. The updated mechanism was employed for the computer simulation of plasma-assisted combustion of hydrogen-air and methane-air mixtures under high pressure and in the range of initial temperatures T  =  500-900 K. The updated mechanism was verified using the experimental data. The influence of electronically excited nitrogen on the ignition delay time was analyzed. The rate coefficient of the vibration-vibration exchange between N2 and HO2 was calculated as well as the rate coefficient of HO2 decomposition.

  14. A gas-phase reactor powered by solar energy and ethanol for H2 production

    International Nuclear Information System (INIS)

    Ampelli, Claudio; Genovese, Chiara; Passalacqua, Rosalba; Perathoner, Siglinda; Centi, Gabriele

    2014-01-01

    In the view of H 2 as the future energy vector, we presented here the development of a homemade photo-reactor working in gas phase and easily interfacing with fuel cell devices, for H 2 production by ethanol dehydrogenation. The process generates acetaldehyde as the main co-product, which is more economically advantageous with respect to the low valuable CO 2 produced in the alternative pathway of ethanol photoreforming. The materials adopted as photocatalysts are based on TiO 2 substrates but properly modified with noble (Au) and not-noble (Cu) metals to enhance light harvesting in the visible region. The samples were characterized by BET surface area analysis, Transmission Electron Microscopy (TEM) and UV–visible Diffusive Reflectance Spectroscopy, and finally tested in our homemade photo-reactor by simulated solar irradiation. We discussed about the benefits of operating in gas phase with respect to a conventional slurry photo-reactor (minimization of scattering phenomena, no metal leaching, easy product recovery, etc.). Results showed that high H 2 productivity can be obtained in gas phase conditions, also irradiating titania photocatalysts doped with not-noble metals. - Highlights: • A gas-phase photoreactor for H 2 production by ethanol dehydrogenation was developed. • The photocatalytic behaviours of Au and Cu metal-doped TiO 2 thin layers are compared. • Benefits of operating in gas phase with respect to a slurry reactor are presented. • Gas phase conditions and use of not-noble metals are the best economic solution

  15. Studies of cluster-assembled materials: From gas phase to condensed phase

    Science.gov (United States)

    Gao, Lin

    . After being mass gated in a reflectron equipped time-of-flight mass spectrometer (TOF-MS) and deposited onto TEM grids, the resultant specimens can be loaded onto high-resolution TEM investigation via electron diffraction. In conclusion, soft-landing of mass selected clusters has been shown to be a successful approach to obtain structural information on Zr-Met-Car cluster-assembled materials collected from the gas phase. TEM images indicate the richness of the morphologies associated with these cluster crystals. However, passivation methods are expected to be examined further to overcome the limited stabilities of these novel clusters. From this initial study, it's shown the promising opportunity to study other Met-Cars species and more cluster-based materials. Experimental results of reactions run with a solvothermal synthesis method obtained while searching for new Zr-C cluster assembled materials, are reported. One unexpected product in single crystal form was isolated and tentatively identified by X-ray diffraction to be [Zr6i O(OH)O12·2(Bu)4], with space group P2 1/n and lattice parameters of a = 12.44 A, b = 22.06 A, c = 18.40 A, alpha = 90°, beta = 105°, gamma = 90°, V = 4875 A3 and R 1 = 3.15% for the total observed data (I ≥ 2 sigma I) and oR2 = 2.82%. This novel hexanuclear Zr(IV)-oxo-hydroxide cluster anion may be the first member in polyoxometalates class with metal atoms from the IVB group and having Oh symmetry. Alternatively, it may be the first member in {[(Zr6Z)X 12]X6}m- class with halides replaced by oxo- and hydroxyl groups and with an increased oxidation state of Zr. It is predicted to bear application potentials directed by both families. This work could suggest a direction in which the preparation of Zr-C cluster-assembled materials in a liquid environment may be eventually fulfilled. 1,3-Bis(diethylphosphino)propane (depp) protected small gold clusters are studied via multiple techniques, including Electrospray Ionization Mass Spectrometry

  16. Application of Electromagnetic Induction Technique to Measure the Void Fraction in Oil/Gas Two Phase Flow

    Science.gov (United States)

    Wahhab, H. A. Abdul; Aziz, A. R. A.; Al-Kayiem, H. H.; Nasif, M. S.; Reda, M. N.

    2018-03-01

    In this work, electromagnetic induction technique of measuring void fraction in liquid/gas fuel flow was utilized. In order to improve the electric properties of liquid fuel, an iron oxide Fe3O4 nanoparticles at 3% was blended to enhance the liquid fuel magnetization. Experiments have been conducted for a wide range of liquid and gas superficial velocities. From the experimental results, it was realized that there is an existing linear relationship between the void fraction and the measured electromotive force, when induction coils were connected in series for excitation coils, regardless of increase or decrease CNG bubbles distribution in liquid fuel flow. Therefore, it was revealed that the utilized method yielded quite reasonable account for measuring the void fraction, showing good agreement with the other available measurement techniques in the two-phase flow, and also with the published literature of the bubbly flow pattern. From the results of the present investigation, it has been proven that the electromagnetic induction is a feasible technique for the actual measurement of void fraction in a Diesel/CNG fuel flow.

  17. Axial- and radial-resolved electron density and excitation temperature of aluminum plasma induced by nanosecond laser: Effect of the ambient gas composition and pressure

    Directory of Open Access Journals (Sweden)

    Mahmoud S. Dawood

    2015-11-01

    Full Text Available The spatial variation of the characteristics of an aluminum plasma induced by a pulsed nanosecond XeCl laser is studied in this paper. The electron density and the excitation temperature are deduced from time- and space- resolved Stark broadening of an ion line and from a Boltzmann diagram, respectively. The influence of the gas pressure (from vacuum up to atmospheric pressure and compositions (argon, nitrogen and helium on these characteristics is investigated. It is observed that the highest electron density occurs near the laser spot and decreases by moving away both from the target surface and from the plume center to its edge. The electron density increases with the gas pressure, the highest values being occurred at atmospheric pressure when the ambient gas has the highest mass, i.e. in argon. The excitation temperature is determined from the Boltzmann plot of line intensities of iron impurities present in the aluminum target. The highest temperature is observed close to the laser spot location for argon at atmospheric pressure. It decreases by moving away from the target surface in the axial direction. However, no significant variation of temperature occurs along the radial direction. The differences observed between the axial and radial direction are mainly due to the different plasma kinetics in both directions.

  18. New technique for the direct analysis of food powders confined in a small hole using transversely excited atmospheric CO(2) laser-induced gas plasma.

    Science.gov (United States)

    Khumaeni, Ali; Ramli, Muliadi; Deguchi, Yoji; Lee, Yong Inn; Idris, Nasrullah; Kurniawan, Koo Hendrik; Lie, Tjung Jie; Kagawa, Kiichiro

    2008-12-01

    Taking advantage of the differences between the interactions of transversely excited atmospheric (TEA) CO(2) lasers with metal and with organic powder, a new technique for the direct analysis of food powder samples has been developed. In this technique, the powder samples were placed into a small hole with a diameter of 2 mm and a depth of 3 mm and covered by a metal mesh. The TEA CO(2) laser (1500 mJ, 200 ns) was focused on the powder sample surfaces, passing through the metal mesh, at atmospheric pressure in nitrogen gas. It is hypothesized that the small hole functions to confine the powder particles and suppresses the blowing-off of sample, while the metal mesh works as the source of electrons to initiate the strong gas breakdown plasma. The confined powder particles are then ablated by laser irradiation and the ablated particles move into the strong gas breakdown plasma region to be atomized and excited; this method cannot be applied for the case of Nd:YAG lasers because in such case the metal mesh itself was ablated by the laser irradiation. A quantitative analysis of a milk powder sample containing different concentrations of Ca was successfully demonstrated, resulting in a good linear calibration curve with high precision.

  19. Research in Korea on Gas Phase Synthesis and Control of Nanoparticles

    International Nuclear Information System (INIS)

    Choi, Mansoo

    2001-01-01

    Research activity into the gas phase synthesis of nanoparticles has witnessed rapid growth on a worldwide basis, which is also reflected by Korean research efforts. Nanoparticle research is inherently a multi-disciplinary activity involving both science and engineering. In this paper, the recent studies undertaken in Korea on the gas phase synthesis and control of nanoparticles are reviewed. Studies on the synthesis of various kinds of nanoparticles are first discussed with a focus on the different types of reactors used. Recent experimental and theoretical studies and newly developed methods of measuring and modeling nanoparticle growth are also reviewed

  20. Direct gas-phase epoxidation of propylene to propylene oxide through radical reactions: A theoretical study

    Science.gov (United States)

    Kizilkaya, Ali Can; Fellah, Mehmet Ferdi; Onal, Isik

    2010-03-01

    The gas-phase radical chain reactions which utilize O 2 as the oxidant to produce propylene oxide (PO) are investigated through theoretical calculations. The transition states and energy profiles were obtained for each path. The rate constants were also calculated. The energetics for the competing pathways indicate that PO can be formed selectively due to its relatively low activation barrier (9.3 kcal/mol) which is in a good agreement with the experimental value (11 kcal/mol) of gas-phase propylene epoxidation. The formation of the acrolein and combustion products have relatively high activation barriers and are not favored. These results also support the recent experimental findings.

  1. Acrolein Production by Gas-Phase Glycerol Dehydration Using PO₄/Nb₂O5 Catalysts.

    Science.gov (United States)

    Lee, Kyu Am; Ryoo, HeeKyoung; Ma, Byung Chol; Kim, Youngchul

    2018-02-01

    In this study, modified niobium oxide were prepared to study the addictive effects on the catalytic performance for gas-phase glycerol dehydration. The catalysts were characterized by N2 adsorption/desorption, XRD, NH3-TPD, FT-IR. The amount of phosphoric acid was up to 50 wt% in niobium. As a result, the highest glycerol conversion was achieved over 20 wt% PO4/Nb2O5. It indicates that the optimal amount of phosphoric acid leads the catalyst to have appropriate acidity which is an important factor for gas-phase glycerol dehydration.

  2. Gas phase THz spectroscopy of toxic agent simulant compounds using the AILES synchrotron beamline

    Science.gov (United States)

    Cuisset, A.; Smirnova, I.; Bocquet, R.; Hindle, F.; Mouret, G.; Yang, C.; Pirali, O.; Roy, P.

    2010-02-01

    A new study is currently underway aiming at recording and assigning the gas phase rovibrational spectra of several organophosphorus and organosulphur compounds in the THz frequency domain. Thanks to the exceptional properties of flux, brilliance and spectral range of the AILES beamline coupled to the FTIR spectrometer, the gas phase vibrational spectra of low volatility organophosphorous compounds have been recorded across the entire THz frequency range. High resolution FTIR spectroscopy was used to record the pure rotational and the low-frequency rovibrational spectrum of DMSO. A comparison between the spectra measured with the AILES beamline and the spectra obtained with optoelectronic THz sources is possible.

  3. Studies of gas phase ion/molecule reactions by Fourier transform ion cyclotron resonance mass spectrometry

    International Nuclear Information System (INIS)

    Kleingeld, J.C.

    1984-01-01

    An important field in which Fourier-transform ion cyclotron resonance has useful applications is that of gas phase ion chemistry, the subject of this thesis. First, the general picture of ion-molecule reactions in the gas phase is discussed. Next, some positive ion-molecule reactions are described, whereas the remaining chapters deal with negative ion-molecule reactions. Most of these studies have been performed using the FT-ICR method. Reactions involving H 3 O - and NH 4 - ions are described whereas the other chapters deal with larger organic complexes. (Auth.)

  4. Parents of two-phase flow and theory of “gas-lift”

    Directory of Open Access Journals (Sweden)

    Zitek Pavel

    2014-03-01

    Full Text Available This paper gives a brief overview of types of two-phase flow. Subsequently, it deals with their mutual division and problems with accuracy boundaries among particular types. It also shows the case of water flow through a pipe with external heating and the gradual origination of all kinds of flow. We have met it in solution of safety condition of various stages in pressurized and boiling water reactors. In the MSR there is a problem in the solution of gas-lift using helium as a gas and its secondary usage for clearing of the fuel mixture from gaseous fission products. Theory of gas-lift is described.

  5. Parents of two-phase flow and theory of "gas-lift"

    Science.gov (United States)

    Zitek, Pavel; Valenta, Vaclav

    2014-03-01

    This paper gives a brief overview of types of two-phase flow. Subsequently, it deals with their mutual division and problems with accuracy boundaries among particular types. It also shows the case of water flow through a pipe with external heating and the gradual origination of all kinds of flow. We have met it in solution of safety condition of various stages in pressurized and boiling water reactors. In the MSR there is a problem in the solution of gas-lift using helium as a gas and its secondary usage for clearing of the fuel mixture from gaseous fission products. Theory of gas-lift is described.

  6. Molecular simulation of excess isotherm and excess enthalpy change in gas-phase adsorption.

    Science.gov (United States)

    Do, D D; Do, H D; Nicholson, D

    2009-01-29

    We present a new approach to calculating excess isotherm and differential enthalpy of adsorption on surfaces or in confined spaces by the Monte Carlo molecular simulation method. The approach is very general and, most importantly, is unambiguous in its application to any configuration of solid structure (crystalline, graphite layer or disordered porous glass), to any type of fluid (simple or complex molecule), and to any operating conditions (subcritical or supercritical). The behavior of the adsorbed phase is studied using the partial molar energy of the simulation box. However, to characterize adsorption for comparison with experimental data, the isotherm is best described by the excess amount, and the enthalpy of adsorption is defined as the change in the total enthalpy of the simulation box with the change in the excess amount, keeping the total number (gas + adsorbed phases) constant. The excess quantities (capacity and energy) require a choice of a reference gaseous phase, which is defined as the adsorptive gas phase occupying the accessible volume and having a density equal to the bulk gas density. The accessible volume is defined as the mean volume space accessible to the center of mass of the adsorbate under consideration. With this choice, the excess isotherm passes through a maximum but always remains positive. This is in stark contrast to the literature where helium void volume is used (which is always greater than the accessible volume) and the resulting excess can be negative. Our definition of enthalpy change is equivalent to the difference between the partial molar enthalpy of the gas phase and the partial molar enthalpy of the adsorbed phase. There is no need to assume ideal gas or negligible molar volume of the adsorbed phase as is traditionally done in the literature. We illustrate this new approach with adsorption of argon, nitrogen, and carbon dioxide under subcritical and supercritical conditions.

  7. Two phases of the anyon gas and broken T symmetry

    International Nuclear Information System (INIS)

    Canright, G.S.; Rojo, A.G.

    1991-01-01

    This paper reports the first exact finite-temperature study of anyons. The authors' method is an extension to finite T of earlier numerical work with small numbers of anyons on a lattice. We study the spontaneous magnetization M 0 (T), since the signature has been identified as a key signature of broken T symmetry for anyon models. Our results confirm the two-phase picture suggested by earlier work: The authors find a low-temperature regime where M 0 is very small or zero, and a high-temperature regime where M 0 is of O(0.1 μ B ) per particle. In the high-temperature regime the authors can obtain an excellent estimate of M 0 (T) in the thermodynamic limit (which we call M 0 ∞ ). since our finite-size results extrapolate smoothly with little scatter. The authors' values for M 0 ∞ can then be compared with the results of μSR experiments on high-temperature superconductors, which set an upper experimental bound on the internal fields from such moments. The authors find that M 0 ∞ in a bulk material of many planes will almost certainly give a signal well above this threshold if (and only if) the planes are ordered ferromagnetically. In the antiferromagnetic case (which is strongly favored energetically) the signal from M 0 ∞ is probably undetectable. Finally, we estimate the transition temperature T c from our finite-size studies, obtaining a value on the order of a few hundred Kelvins

  8. Experimental on two sensors combination used in horizontal pipe gas-water two-phase flow

    International Nuclear Information System (INIS)

    Wu, Hao; Dong, Feng

    2014-01-01

    Gas-water two phase flow phenomenon widely exists in production and living and the measurement of it is meaningful. A new type of long-waist cone flow sensor has been designed to measure two-phase mass flow rate. Six rings structure of conductance probe is used to measure volume fraction and axial velocity. The calibration of them have been made. Two sensors have been combined in horizontal pipeline experiment to measure two-phase flow mass flow rate. Several model of gas-water two-phase flow has been discussed. The calculation errors of total mass flow rate measurement is less than 5% based on the revised homogeneous flow model

  9. The nuclear liquid-gas phase transition: Present status and future perspectives

    International Nuclear Information System (INIS)

    Pochodzalla, J.; Imme, G.; Maddalena, V.

    1996-07-01

    More than two decades ago, the van der Waals behavior of the nucleon -nucleon force inspired the idea of a liquid-gas phase transition in nuclear matter. Heavy-ion reactions at relativistic energies offer the unique possibility for studying this phase transition in a finite, hadronic system. A general overview of this subject is given emphasizing the most recent results on nuclear calorimetry. (orig.)

  10. Isospin and momentum dependence of liquid-gas phase transition in hot asymmetric nuclear matter

    International Nuclear Information System (INIS)

    Xu, Jun; Ma, Hongru; Chen, Liewen; Li, Baoan

    2008-01-01

    The liquid-gas phase transition in hot neutron-rich nuclear matter is investigated within a self-consistent thermal model using different interactions with or without isospin and/or momentum dependence. The boundary of the phase-coexistence region is shown to be sensitive to the density dependence of the nuclear symmetry energy as well as the isospin and momentum dependence of the nuclear interaction. (author)

  11. Quantitation of anticonvulsant drugs in serum by gas-chromatography on the stationary phase SP-2510.

    Science.gov (United States)

    Godolphin, W; Thoma, J

    1978-03-01

    A new column packing, SP-2510 DA (Supelco, Inc., Bellefonte, Pa. 16823), is an excellent stationary phase for the determination of a wide variety of anticonvulsant drugs by gas--liquid chromatography without derivatization. However, when uncomplicated extraction procedures are used, serum cholesterol interferes with the determination of primidone. By the simple expedient of adding a short "pre-column" containing another phase (SP-2250 DA) the problem is overcome.

  12. Isothermal phase equilibria for the (HFC-32 + HFC-134a) mixed-gas hydrate system

    International Nuclear Information System (INIS)

    Miyauchi, Hiroshi; Yasuda, Kenjiro; Matsumoto, Yuuki; Hashimoto, Shunsuke; Sugahara, Takeshi; Ohgaki, Kazunari

    2012-01-01

    Highlights: ► Structural phase transition results in the heterogeneous azeotropic-like behaviour. ► HFC-134a molecules, in spite of an s-II former, occupy the large cages of s-I. ► Negative azeotropic-like behaviour becomes more remarkable at higher temperatures. - Abstract: Isothermal phase equilibria (pressure-composition relations in hydrate, gas, and aqueous phases) in the {difluoromethane (HFC-32) + 1,1,1,2-tetrafluoroethane (HFC-134a)} mixed-gas hydrate system were measured at the temperatures 274.15 K, 279.15 K, and 283.15 K. The heterogeneous azeotropic-like behaviour derived from the structural phase transition of (HFC-32 + HFC-134a) mixed-gas hydrates appears over the whole temperature range of the present study. In addition to the heterogeneous azeotropic-like behaviour, the isothermal phase equilibrium curves of the (HFC-32 + HFC-134a) mixed-gas hydrate system exhibit the negative homogeneous azeotropic-like behaviour at temperatures 279.15 K and 283.15 K. The negative azeotropic-like behaviour, which becomes more remarkable at higher temperatures, results in the lower equilibrium pressure of (HFC-32 + HFC-134a) mixed-gas hydrates than those of both simple HFC-32 and HFC-134a hydrates. Although the HFC-134a molecule forms the simple structure-II hydrate at the temperatures, the present findings reveal that HFC-134a molecules occupy a part of the large cages of the structure-I mixed-gas hydrate.

  13. Gas-phase spectra of MgO molecules: a possible connection from gas-phase molecules to planet formation

    Science.gov (United States)

    Kloska, Katherine A.; Fortenberry, Ryan C.

    2018-02-01

    A more fine-tuned method for probing planet-forming regions, such as protoplanetary discs, could be rovibrational molecular spectroscopy observation of particular premineral molecules instead of more common but ultimately less related volatile organic compounds. Planets are created when grains aggregate, but how molecules form grains is an ongoing topic of discussion in astrophysics and planetary science. Using the spectroscopic data of molecules specifically involved in mineral formation could help to map regions where planet formation is believed to be occurring in order to examine the interplay between gas and dust. Four atoms are frequently associated with planetary formation: Fe, Si, Mg and O. Magnesium, in particular, has been shown to be in higher relative abundance in planet-hosting stars. Magnesium oxide crystals comprise the mineral periclase making it the chemically simplest magnesium-bearing mineral and a natural choice for analysis. The monomer, dimer and trimer forms of (MgO)n with n = 1-3 are analysed in this work using high-level quantum chemical computations known to produce accurate results. Strong vibrational transitions at 12.5, 15.0 and 16.5 μm are indicative of magnesium oxide monomer, dimer and trimer making these wavelengths of particular interest for the observation of protoplanetary discs and even potentially planet-forming regions around stars. If such transitions are observed in emission from the accretion discs or absorptions from stellar spectra, the beginning stages of mineral and, subsequently, rocky body formation could be indicated.

  14. Determination of electron impact ionization and excitation coefficients in He-Xe gas mixtures. He-Xe kongo gas ni okeru denshi shototsu denri keisu oyobi reiki keisu no sokutei to kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, K.; Tachibana, K. (Kyoto Inst. of Technology, Kyoto (Japan))

    1991-03-20

    The rare gas discharge gives a stable discharge and light emission characteristics at low temperature in comparison with the discharge of the vapor of such a metal as Hg. The present barrier for the commercialization of the color PDP lies in the lower level of its emission intensity and efficiency in comparison with that of CRT. In this report, an electron impact ionization coefficient in a gas mixture and an electron impact excitation coefficient for a XeIs {sub 4} level were analyzed using a Boltzmann equation by means of a steady state Townsend method using a drift tube. By comparing both, the elementary process in the gas mixture is investiagted to discuss the respective contributions for the effective ionization coefficient and the excitation coefficient. As a result, it was found that the ionization process in the He-Xe gas mixture could be described by the processes of direct ionization of Xe and He, and an indirect ionization (Penning effect) by an active helium. 37 refs., 12 figs.

  15. Ground-State Gas-Phase Structures of Inorganic Molecules Predicted by Density Functional Theory Methods

    KAUST Repository

    Minenkov, Yury

    2017-11-29

    We tested a battery of density functional theory (DFT) methods ranging from generalized gradient approximation (GGA) via meta-GGA to hybrid meta-GGA schemes as well as Møller–Plesset perturbation theory of the second order and a single and double excitation coupled-cluster (CCSD) theory for their ability to reproduce accurate gas-phase structures of di- and triatomic molecules derived from microwave spectroscopy. We obtained the most accurate molecular structures using the hybrid and hybrid meta-GGA approximations with B3PW91, APF, TPSSh, mPW1PW91, PBE0, mPW1PBE, B972, and B98 functionals, resulting in lowest errors. We recommend using these methods to predict accurate three-dimensional structures of inorganic molecules when intramolecular dispersion interactions play an insignificant role. The structures that the CCSD method predicts are of similar quality although at considerably larger computational cost. The structures that GGA and meta-GGA schemes predict are less accurate with the largest absolute errors detected with BLYP and M11-L, suggesting that these methods should not be used if accurate three-dimensional molecular structures are required. Because of numerical problems related to the integration of the exchange–correlation part of the functional and large scattering of errors, most of the Minnesota models tested, particularly MN12-L, M11, M06-L, SOGGA11, and VSXC, are also not recommended for geometry optimization. When maintaining a low computational budget is essential, the nonseparable gradient functional N12 might work within an acceptable range of error. As expected, the DFT-D3 dispersion correction had a negligible effect on the internuclear distances when combined with the functionals tested on nonweakly bonded di- and triatomic inorganic molecules. By contrast, the dispersion correction for the APF-D functional has been found to shorten the bonds significantly, up to 0.064 Å (AgI), in Ag halides, BaO, BaS, BaF, BaCl, Cu halides, and Li and

  16. Oxidative potential of gas phase combustion emissions - An underestimated and potentially harmful component of air pollution from combustion processes

    Science.gov (United States)

    Stevanovic, S.; Vaughan, A.; Hedayat, F.; Salimi, F.; Rahman, M. M.; Zare, A.; Brown, R. A.; Brown, R. J.; Wang, H.; Zhang, Z.; Wang, X.; Bottle, S. E.; Yang, I. A.; Ristovski, Z. D.

    2017-06-01

    The oxidative potential (OP) of the gas phase is an important and neglected aspect of environmental toxicity. Whilst prolonged exposure to particulate matter (PM) associated reactive oxygen species (ROS) have been shown to lead to negative health effects, the potential for compounds in gas phase to cause similar effects is yet to be understood. In this study we describe: the significance of the gas phase OP generated through vehicle emissions; discuss the origin and evolution of species contributing to measured OP; and report on the impact of gas phase OP on human lung cells. The model aerosol for this study was exhaust emitted from a Euro III Common-rail diesel engine fuelled with different blends of diesel and biodiesel. The gas phase of these emissions was found to be potentially as hazardous as the particle phase. Fuel oxygen content was found to negatively correlate with the gas phase OP, and positively correlate with particle phase OP. This signifies a complex interaction between reactive species present in gas and particle phase. Furthermore, this interaction has an overarching effect on the OP of both particle and gas phase, and therefore the toxicity of combustion emissions.

  17. Magnetic resonance velocity imaging of liquid and gas two-phase flow in packed beds.

    Science.gov (United States)

    Sankey, M H; Holland, D J; Sederman, A J; Gladden, L F

    2009-02-01

    Single-phase liquid flow in porous media such as bead packs and model fixed bed reactors has been well studied by MRI. To some extent this early work represents the necessary preliminary research to address the more challenging problem of two-phase flow of gas and liquid within these systems. In this paper, we present images of both the gas and liquid velocities during stable liquid-gas flow of water and SF(6) within a packing of 5mm spheres contained within columns of diameter 40 and 27 mm; images being acquired using (1)H and (19)F observation for the water and SF(6), respectively. Liquid and gas flow rates calculated from the velocity images are in agreement with macroscopic flow rate measurements to within 7% and 5%, respectively. In addition to the information obtained directly from these images, the ability to measure liquid and gas flow fields within the same sample environment will enable us to explore the validity of assumptions used in numerical modelling of two-phase flows.

  18. A modeling and experimental study of flue gas desulfurization in a dense phase tower

    International Nuclear Information System (INIS)

    Chang, Guanqin; Song, Cunyi; Wang, Li

    2011-01-01

    We used a dense phase tower as the reactor in a novel semi-dry flue gas desulfurization process to achieve a high desulfurization efficiency of over 95% when the Ca/S molar ratio reaches 1.3. Pilot-scale experiments were conducted for choosing the parameters of the full-scale reactor. Results show that with an increase in the flue gas flow rate the rate of the pressure drop in the dense phase tower also increases, however, the rate of the temperature drop decreases in the non-load hot gas. We chose a water flow rate of 0.6 kg/min to minimize the approach to adiabatic saturation temperature difference and maximize the desulfurization efficiency. To study the flue gas characteristics under different processing parameters, we simulated the desulfurization process in the reactor. The simulated data matched very well with the experimental data. We also found that with an increase in the Ca/S molar ratio, the differences between the simulation and experimental data tend to decrease; conversely, an increase in the flue gas flow rate increases the difference; this may be associated with the surface reactions caused by collision, coalescence and fragmentation between the dispersed phases.

  19. Ethanol- and trifluoroethanol-induced changes in phase states of DPPC membranes. Prodan emission-excitation fluorescence spectroscopy supported by PARAFAC analysis

    Science.gov (United States)

    Horochowska, Martyna; Cieślik-Boczula, Katarzyna; Rospenk, Maria

    2018-03-01

    It has been shown that Prodan emission-excitation fluorescence spectroscopy supported by Parallel Factor (PARAFAC) analysis is a fast, simple and sensitive method used in the study of the phase transition from the noninterdigitated gel (Lβ‧) state to the interdigitated gel (LβI) phase, triggered by ethanol and 2,2,2-trifluoroethanol (TFE) molecules in dipalmitoylphosphatidylcholines (DPPC) membranes. The relative contribution of lipid phases with spectral characteristics of each pure phase component has been presented as a function of an increase in alcohol concentration. It has been stated that both alcohol molecules can induce a formation of the LβI phase, but TFE is over six times stronger inducer of the interdigitated phase in DPPC membranes than ethanol molecules. Moreover, in the TFE-mixed DPPC membranes, the transition from the Lβ‧ to LβI phase is accompanied by a formation of the fluid phase, which most probably serves as a boundary phase between the Lβ‧ and LβI regions. Contrary to the three phase-state model of TFE-mixed DPPC membranes, in ethanol-mixed DPPC membranes only the two phase-state model has been detected.

  20. Measurement of phase interaction in dispersed gas-particle two-phase flow by phase-doppler anemometry

    OpenAIRE

    Mergheni Ali Mohamed; Ben Ticha Hmaied; Sautet Jen-Charles; Godard Gille; Ben Nasrallah Sassi

    2008-01-01

    For simultaneous measurement of size and velocity distributions of continuous and dispersed phases in a two-phase flow a technique phase-Doppler anemometry was used. Spherical glass particles with a particle diameter range from 102 up to 212 µm were used. In this two-phase flow an experimental results are presented which indicate a significant influence of the solid particles on the flow characteristics. The height of influence of these effects depends on the local position in the jet. Near t...

  1. Do medium heavy fragments give evidence for a liquid-gas phase transition

    International Nuclear Information System (INIS)

    Trockel, R.; Hildenbrand, K.D.; Lynen, U.; Mueller, W.F.J.; Rabe, H.J.; Sann, H.; Stelzer, H.; Wada, R.; Brummund, N.; Glasow, R.; Kampert, K.H.; Santo, R.; Pelte, D.; Pochodzalla, J.; Eckert, E.

    1985-09-01

    Light and medium heavy fragments have been measured in light ion induced reactions at intermediate energies. The energy spectra have been parametrized with moving source fits. The resulting temperatures and yields do not confirm the expectations of a liquid-gas phase transition. (orig.)

  2. Electron Attachment to the Gas Phase DNA Bases Cytosine and Thymine

    Czech Academy of Sciences Publication Activity Database

    Denifl, S.; Ptasiňska, S.; Probst, M.; Hrušák, Jan; Scheier, P.; Märk, T. D.

    2004-01-01

    Roč. 108, č. 31 (2004), s. 6562-6569 ISSN 1089-5639 R&D Projects: GA ČR GA203/02/0737 Institutional research plan: CEZ:AV0Z4040901 Keywords : gas-phase * cytosine * thymine Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.639, year: 2004

  3. How Pt nanoparticles affect TiO2-induced gas-phase photocatalytic oxidation reactions

    NARCIS (Netherlands)

    Fraters, B.D.; Amrollahi Buky, Rezvaneh; Mul, Guido

    2015-01-01

    The effect of Pt nanoparticles on the gas-phase photocatalytic oxidation activity of TiO2 is shown to be largely dependent on the molecular functionality of the substrate. We demonstrate that Pt nanoparticles decrease rates in photocatalytic oxidation of propane, whereas a strong beneficial effect

  4. A gas phase work station for the Brazilian National Synchrotron Laboratory

    International Nuclear Information System (INIS)

    Souza, G.G.B. de

    1988-01-01

    A gas phase work station which has been proposed to the Brazilian National Synchrotron Laboratory is described with emphasis on the broad spectrum of physical and chemical processes which can be studied with the incorporated instrumentation. (A.C.A.S.) [pt

  5. The constitutive distributed parameter model of multicomponent chemical processes in gas, fluid and solid phase

    International Nuclear Information System (INIS)

    Niemiec, W.

    1985-01-01

    In the literature of distributed parameter modelling of real processes is not considered the class of multicomponent chemical processes in gas, fluid and solid phase. The aim of paper is constitutive distributed parameter physicochemical model, constructed on kinetics and phenomenal analysis of multicomponent chemical processes in gas, fluid and solid phase. The mass, energy and momentum aspects of these multicomponent chemical reactions and adequate phenomena are utilized in balance operations, by conditions of: constitutive invariance for continuous media with space and time memories, reciprocity principle for isotropic and anisotropic nonhomogeneous media with space and time memories, application of definitions of following derivative and equation of continuity, to the construction of systems of partial differential constitutive state equations, in the following derivative forms for gas, fluid and solid phase. Couched in this way all physicochemical conditions of multicomponent chemical processes in gas, fluid and solid phase are new form of constitutive distributed parameter model for automatics and its systems of equations are new form of systems of partial differential constitutive state equations in sense of phenomenal distributed parameter control

  6. Role of isospin in nuclear-matter liquid-gas phase transition

    International Nuclear Information System (INIS)

    Ducoin, C.

    2006-10-01

    Nuclear matter presents a phase transition of the liquid-gas type. This well-known feature is due to the nuclear interaction profile (mean-range attractive, short-range repulsive). Symmetric-nuclear-matter thermodynamics is thus analogous to that of a Van der Waals fluid. The study shows up to be more complex in the case of asymmetric matter, composed of neutrons and protons in an arbitrary proportion. Isospin, which distinguishes both constituents, gives a measure of this proportion. Studying asymmetric matter, isospin is an additional degree of freedom, which means one more dimension to consider in the space of observables. The nuclear liquid-gas transition is associated with the multi-fragmentation phenomenon observed in heavy-ion collisions, and to compact-star physics: the involved systems are neutron rich, so they are affected by the isospin degree of freedom. The present work is a theoretical study of isospin effects which appear in the asymmetric nuclear matter liquid-gas phase transition. A mean-field approach is used, with a Skyrme nuclear effective interaction. We demonstrate the presence of a first-order phase transition for asymmetric matter, and study the isospin distillation phenomenon associated with this transition. The case of phase separation at thermodynamic equilibrium is compared to spinodal decomposition. Finite size effects are addressed, as well as the influence of the electron gas which is present in the astrophysical context. (author)

  7. C-terminal peptide extension via gas-phase ion/ion reactions

    Science.gov (United States)

    Peng, Zhou; McLuckey, Scott A.

    2015-01-01

    The formation of peptide bonds is of great importance from both a biological standpoint and in routine organic synthesis. Recent work from our group demonstrated the synthesis of peptides in the gas-phase via ion/ion reactions with sulfo-NHS reagents, which resulted in conjugation of individual amino acids or small peptides to the N-terminus of an existing ‘anchor’ peptide. Here, we demonstrate a complementary approach resulting in the C-terminal extension of peptides. Individual amino acids or short peptides can be prepared as reagents by incorporating gas phase-labile protecting groups to the reactive C-terminus and then converting the N-terminal amino groups to the active ketenimine reagent. Gas-phase ion/ion reactions between the anionic reagents and doubly protonated “anchor” peptide cations results in extension of the “anchor” peptide with new amide bond formation at the C-terminus. We have demonstrated that ion/ion reactions can be used as a fast, controlled, and efficient means for C-terminal peptide extension in the gas phase. PMID:26640400

  8. ECO LOGIC INTERNATIONAL GAS-PHASE CHEMICAL REDUCTION PROCESS - THE THERMAL DESORPTION UNIT - APPLICATIONS ANALYSIS REPORT

    Science.gov (United States)

    ELI ECO Logic International, Inc.'s Thermal Desorption Unit (TDU) is specifically designed for use with Eco Logic's Gas Phase Chemical Reduction Process. The technology uses an externally heated bath of molten tin in a hydrogen atmosphere to desorb hazardous organic compounds fro...

  9. Structure Elucidation of Dimethylformamide-Solvated Alkylzinc Cations in the Gas Phase

    NARCIS (Netherlands)

    Dreiocker, F.; Oomens, J.; Meijer, Ajhm; Pickup, B. T.; Jackson, R. F. W.; Schafer, M.

    2010-01-01

    Organozinc iodides, useful for the synthesis of nonproteinogenic amino acids, are investigated in the gas phase by a combination of electrospray (ESI)-MS/MS, accurate ion mass measurements, and infrared multiphoton dissociation (IRMPD) spectroscopy employing a free electron laser. ESI allowed the

  10. Gas-phase infrared spectrum of the anionic GFP-chromophore

    NARCIS (Netherlands)

    Almasian, M.; Grzetic, J.; G. Berden,; Bakker, B.; Buma, W. J.; Oomens, J.

    2012-01-01

    The gas-phase IR spectrum of the anionic chromophore of the green fluorescent protein (p-hydroxy-benzylidene-2,3-dimethylimidazolidinone, HBDI) is recorded in the 800–1800 cm−1 frequency range using the free electron laser FELIX in combination with an electrospray ionization (ESI) Fourier

  11. Structure elucidation of dimethylformamide-solvated alkylzinc cations in the gas phase

    NARCIS (Netherlands)

    Dreiocker, F.; Oomens, J.; Meijer, A.J.H.M.; Pickup, B.T.; Jackson, R.F.W.; Schäfer, M.

    2010-01-01

    Organozinc iodides, useful for the synthesis of nonproteinogenic amino acids, are investigated in the gas phase by a combination of electrospray (ESI)-MS/MS, accurate ion mass measurements, and infrared multiphoton dissociation (IRMPD) spectroscopy employing a free electron laser. ESI allowed the

  12. Gas-phase salt bridge interactions between glutamic acid and arginine

    NARCIS (Netherlands)

    Jaeqx, S.; Oomens, J.; Rijs, A.M.

    2013-01-01

    The gas-phase side chain-side chain (SC-SC) interaction and possible proton transfer between glutamic acid (Glu) and arginine (Arg) residues are studied under low-temperature conditions in an overall neutral peptide. Conformation-specific IR spectra, obtained with the free electron laser FELIX, in

  13. Humidity independent mass spectrometry for gas phase chemical analysis via ambient proton transfer reaction.

    Science.gov (United States)

    Zhu, Hongying; Huang, Guangming

    2015-03-31

    In this work, a humidity independent mass spectrometric method was developed for rapid analysis of gas phase chemicals. This method is based upon ambient proton transfer reaction between gas phase chemicals and charged water droplets, in a reaction chamber with nearly saturate humidity under atmospheric pressure. The humidity independent nature enables direct and rapid analysis of raw gas phase samples, avoiding time- and sample-consuming sample pretreatments in conventional mass spectrometry methods to control sample humidity. Acetone, benzene, toluene, ethylbenzene and meta-xylene were used to evaluate the analytical performance of present method. The limits of detection for benzene, toluene, ethylbenzene and meta-xylene are in the range of ∼0.1 to ∼0.3 ppbV; that of benzene is well below the present European Union permissible exposure limit for benzene vapor (5 μg m(-3), ∼1.44 ppbV), with linear ranges of approximately two orders of magnitude. The majority of the homemade device contains a stainless steel tube as reaction chamber and an ultrasonic humidifier as the source of charged water droplets, which makes this cheap device easy to assemble and facile to operate. In addition, potential application of this method was illustrated by the real time identification of raw gas phase chemicals released from plants at different physiological stages. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Ab initio study of gas phase and water-assisted tautomerization of ...

    Indian Academy of Sciences (India)

    WINTEC

    Water-assisted tautomerization in maleimide and formamide showed that difference in energy barrier reduces to 2⋅83 kcal/mol from 10⋅41 kcal/mol (in gas phase) at B3LYP level, which resulted that maleimide readily undergoes tautomerization in water molecule. Keywords. Ab Initio calculations; maleimide; formamide; ...

  15. Gas-phase UF6 enrichment monitor for enrichment plant safeguards

    International Nuclear Information System (INIS)

    Strittmatter, R.B.; Tape, J.W.

    1980-03-01

    An in-line enrichment monitor is being developed to provide real-time enrichment data for the gas-phase UF 6 feed stream of an enrichment plant. The nondestructive gamma-ray assay method can be used to determine the enrichment of natural UF 6 with a relative precision of better than 1% for a wide range of pressures

  16. Mid-IR spectra of different conformers of phenylalanine in the gas phase

    NARCIS (Netherlands)

    von Helden, G.; Compagnon, I.; Blom, M. N.; Frankowski, M.; Erlekam, U.; Oomens, J.; Brauer, B.; Gerber, R. B.; Meijer, G.

    2008-01-01

    The experimental mid- and far-IR spectra of six conformers of phenylalanine in the gas phase are presented. The experimental spectra are compared to spectra calculated at the B3LYP and at the MP2 level. The differences between B3LYP and MP2 IR spectra are found to be small. The agreement between

  17. Constructing a unique two-phase compressibility factor model for lean gas condensates

    Energy Technology Data Exchange (ETDEWEB)

    Moayyedi, Mahmood; Gharesheikhlou, Aliashghar [Research Institute of Petroleum Industry (RIPI), Tehran (Iran, Islamic Republic of); Azamifard, Arash; Mosaferi, Emadoddin [Amirkabir University of Technology (AUT), Tehran (Iran, Islamic Republic of)

    2015-02-15

    Generating a reliable experimental model for two-phase compressibility factor in lean gas condensate reservoirs has always been demanding, but it was neglected due to lack of required experimental data. This study presents the main results of constructing the first two-phase compressibility factor model that is completely valid for Iranian lean gas condensate reservoirs. Based on a wide range of experimental data bank for Iranian lean gas condensate reservoirs, a unique two-phase compressibility factor model was generated using design of experiments (DOE) method and neural network technique (ANN). Using DOE, a swift cubic response surface model was generated for two-phase compressibility factor as a function of some selected fluid parameters for lean gas condensate fluids. The proposed DOE and ANN models were finally validated using four new independent data series. The results showed that there is a good agreement between experimental data and the proposed models. In the end, a detailed comparison was made between the results of proposed models.

  18. Operando Spectroscopy of the Gas-Phase Aldol Condensation of Propanal over Solid Base Catalysts

    NARCIS (Netherlands)

    Hernández-giménez, Ana M.; Ruiz-martínez, Javier; Puértolas, Begoña; Pérez-ramírez, Javier; Bruijnincx, Pieter C. A.; Weckhuysen, Bert M.

    2017-01-01

    The gas-phase aldol condensation of propanal, taken as model for the aldehyde components in bio-oils, has been studied with a combined operando set-up allowing to perform FT-IR & UV–Vis diffuse reflectance spectroscopy (DRS) with on-line mass spectrometry (MS). The selected solid base catalysts, a

  19. Gas-Phase Oxidation of Aqueous Ethanol by Nanoparticle Vanadia/Anatase Catalysts

    DEFF Research Database (Denmark)

    Jørgensen, Betina; Kristensen, Steffen Buus; Kunov-Kruse, Andreas Jonas

    2009-01-01

    The gas-phase oxidation of aqueous ethanol with dioxygen has been examined with a new nanoparticle V2O5/TiO2 catalyst. Product selectivity could to a large extent be controlled by small alterations of reaction parameters, allowing production of acetaldehyde at a selectivity higher than 90%, near...

  20. Study of Iodine Behavior in the Gas Phase during a Severe Accident

    International Nuclear Information System (INIS)

    Kim, Hanchul; Cho, Yeonghun; Ryu, Myunghyun

    2014-01-01

    Among the iodine species, the organic iodides produced from the reaction between iodine and organics such as paint, are not easily trapped by the filters during the containment venting following a severe accident. Korea Institute of Nuclear Safety (KINS) has been studying this issue, joining international research programs such as ISTP-EPICUR, OECDBIP and OECD-STEM. In the course of this study, a simple iodine model, RAIM (Radio-Active Iodine chemistry Model) has been developed (Oh et al., 2011), based on the IMOD methodology, and other previous studies. This paper deals with our recent activities on this study, including the development of the model for the iodine reactions in gas phase. Iodine reactions in gas phase were modeled and added to the RAIM code, taking into account several relevant reactions such as formation of ARP, iodine oxide, and organic iodides in gas phase. RAIM was then applied to analyze the S2-6-5-2 test for which iodine-loaded coupons were tested in gas phase. The analysis results show a reasonable estimation of volatile iodine concentration with the desorption rate constant of about 10 -6 s -1 , while those of the other iodine species overestimated for the whole period of the test. It reveals the need to determine appropriate values for the rate constants for formation of iodine oxides and organic iodides

  1. 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

    to the phase change material, mainly occurs after the fueling is completed, resulting in a hydrogen peak temperature higher than 85 C and a lower fueled mass than a gas-cooled system. Such a mass reduction accounts for 12% with respect to the case of a standard tank system fueled at 40 C. A parametric analysis...

  2. Multiple Multidentate Halogen Bonding in Solution, in the Solid State, and in the (Calculated) Gas Phase.

    Science.gov (United States)

    Jungbauer, Stefan H; Schindler, Severin; Herdtweck, Eberhardt; Keller, Sandro; Huber, Stefan M

    2015-09-21

    The binding properties of neutral halogen-bond donors (XB donors) bearing two multidentate Lewis acidic motifs toward halides were investigated. Employing polyfluorinated and polyiodinated terphenyl and quaterphenyl derivatives as anion receptors, we obtained X-ray crystallographic data of the adducts of three structurally related XB donors with tetraalkylammonium chloride, bromide, and iodide. The stability of these XB complexes in solution was determined by isothermal titration calorimetry (ITC), and the results were compared to X-ray analyses as well as to calculated binding patterns in the gas phase. Density functional theory (DFT) calculations on the gas-phase complexes indicated that the experimentally observed distortion of the XB donors during multiple multidentate binding can be reproduced in 1:1 complexes with halides, whereas adducts with two halides show a symmetric binding pattern in the gas phase that is markedly different from the solid state structures. Overall, this study demonstrates the limitations in the transferability of binding data between solid state, solution, and gas phase in the study of complex multidentate XB donors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Gas-phase synthesis of magnesium nanoparticles : A high-resolution transmission electron microscopy study

    NARCIS (Netherlands)

    Kooi, B.J.; Palasantzas, G.; de Hosson, J.T.M.

    2006-01-01

    Magnesium nanoparticles with size above 10 nm, prepared by gas-phase syntheses, were investigated by high-resolution transmission electron microscopy. The dominant particle shape is a hexagonal prism terminated by Mg(0002) and Mg{1010} facets. Oxidation of Mg yields a MgO shell (similar to 3 nm

  4. Supported Rh-phosphine complex catalysts for continuous gas-phase decarbonylation of aldehydes

    DEFF Research Database (Denmark)

    Malcho, Phillip; Garcia-Suarez, Eduardo J.; Mentzel, Uffe Vie

    2014-01-01

    Heterogeneous silica supported rhodium-phosphine complex catalysts are employed for the first time in the catalytic decarbonylation of aldehydes in continuous gas-phase. The reaction protocol is exemplified for the decarbonylation of p-tolualdehyde to toluene and further extended to other aromatic...

  5. Hydrocarbon fuels from gas phase decarboxylation of hydrolyzed free fatty acid

    KAUST Repository

    Wang, Weicheng; Roberts, William L.; Stikeleather, Larry F.

    2012-01-01

    Gas phase decarboxylation of hydrolyzed free fatty acid (FFA) from canola oil has beeninvestigated in two fix-bed reactors by changing reaction parameters such as temperatures,FFA feed rates, and H 2-to-FFA molar ratios. FFA, which contains mostly C

  6. Gas phase polymerization of propylene. Reaction kinetics and molecular weight distribution

    NARCIS (Netherlands)

    Meier, G.B.; Weickert, G.; van Swaaij, Willibrordus Petrus Maria

    2001-01-01

    Gas-phase polymerizations have been executed at different temperatures, pressures, and hydrogen concentrations using Me2Si[Ind]2ZrCl2 / methylaluminoxane / SiO2(Pennsylvania Quarts) as a catalyst. The reaction rate curves have been described by a kinetic model, which takes into account the initially

  7. Why do disk galaxies present a common gas-phase metallicity gradient?

    Science.gov (United States)

    Chang, R.; Zhang, Shuhui; Shen, Shiyin; Yin, Jun; Hou, Jinliang

    2017-03-01

    CALIFA data show that isolated disk galaxies present a common gas-phase metallicity gradient, with a characteristic slope of -0.1dex/re between 0.3 and 2 disk effective radius re (Sanchez et al. 2014). Here we construct a simple model to investigate which processes regulate the formation and evolution.

  8. Gas-phase photoemission with soft x-rays: cross sections and angular distributions

    International Nuclear Information System (INIS)

    Shirley, D.A.; Kobrin, P.H.; Truesdale, C.M.; Lindle, D.W.; Ferrett, T.A.; Heimann, P.A.; Becker, U.; Kerkhoff, H.G.; Southworth, S.H.

    1983-09-01

    A summary is presented of typical gas-phase photoemission studies based on synchrotron radiation in the 50-5000 eV range, using beam lines at the Stanford Synchrotron Radiation Laboratory. Three topics are addressed: atomic inner-shell photoelectron cross sections and asymmetries, correlation peaks in rare gases, and core-level shape resonances in molecules

  9. Constructing a unique two-phase compressibility factor model for lean gas condensates

    International Nuclear Information System (INIS)

    Moayyedi, Mahmood; Gharesheikhlou, Aliashghar; Azamifard, Arash; Mosaferi, Emadoddin

    2015-01-01

    Generating a reliable experimental model for two-phase compressibility factor in lean gas condensate reservoirs has always been demanding, but it was neglected due to lack of required experimental data. This study presents the main results of constructing the first two-phase compressibility factor model that is completely valid for Iranian lean gas condensate reservoirs. Based on a wide range of experimental data bank for Iranian lean gas condensate reservoirs, a unique two-phase compressibility factor model was generated using design of experiments (DOE) method and neural network technique (ANN). Using DOE, a swift cubic response surface model was generated for two-phase compressibility factor as a function of some selected fluid parameters for lean gas condensate fluids. The proposed DOE and ANN models were finally validated using four new independent data series. The results showed that there is a good agreement between experimental data and the proposed models. In the end, a detailed comparison was made between the results of proposed models

  10. Imaging Molecular Structure through Femtosecond Photoelectron Diffraction on Aligned and Oriented Gas-Phase Molecules

    DEFF Research Database (Denmark)

    Boll, Rebecca; Rouzee, Arnaud; Adolph, Marcus

    2014-01-01

    This paper gives an account of our progress towards performing femtosecond time-resolved photoelectron diffraction on gas-phase molecules in a pump-probe setup combining optical lasers and an X-ray Free-Electron Laser. We present results of two experiments aimed at measuring photoelectron angular...

  11. Structure of the gas-liquid annular two-phase flow in a nozzle section

    International Nuclear Information System (INIS)

    Yoshida, Kenji; Kataoka, Isao; Ohmori, Syuichi; Mori, Michitsugu

    2006-01-01

    Experimental studies on the flow behavior of gas-liquid annular two-phase flow passing through a nozzle section were carried out. This study is concerned with the central steam jet injector for a next generation nuclear reactor. In the central steam jet injector, steam/water annular two-phase flow is formed at the mixing nozzle. To make an appropriate design and to establish the high-performance steam injector system, it is very important to accumulate the fundamental data of the thermo-hydro dynamic characteristics of annular flow passing through a nozzle section. On the other hand, the transient behavior of multiphase flow, in which the interactions between two-phases occur, is one of the most interesting scientific issues and has attracted research attention. In this study, the transient gas-phase turbulence modification in annular flow due to the gas-liquid phase interaction is experimentally investigated. The annular flow passing through a throat section is under the transient state due to the changing cross sectional area of the channel and resultantly the superficial velocities of both phases are changed compared with a fully developed flow in a straight pipe. The measurements for the gas-phase turbulence were precisely performed by using a constant temperature hot-wire anemometer, and made clear the turbulence structure such as velocity profiles, fluctuation velocity profiles. The behavior of the interfacial waves in the liquid film flow such as the ripple or disturbance waves was also observed. The measurements for the liquid film thickness by the electrode needle method were also performed to measure the base film thickness, mean film thickness, maximum film thickness and wave height of the ripple or the disturbance waves. (author)

  12. A cylindrical quadrupole ion trap in combination with an electrospray ion source for gas-phase luminescence and absorption spectroscopy

    International Nuclear Information System (INIS)

    Stockett, Mark H.; Houmøller, Jørgen; Støchkel, Kristian; Svendsen, Annette; Brøndsted Nielsen, Steen

    2016-01-01

    A relatively simple setup for collection and detection of light emitted from isolated photo-excited molecular ions has been constructed. It benefits from a high collection efficiency of photons, which is accomplished by using a cylindrical ion trap where one end-cap electrode is a mesh grid combined with an aspheric condenser lens. The geometry permits nearly 10% of the emitted light to be collected and, after transmission losses, approximately 5% to be delivered to the entrance of a grating spectrometer equipped with a detector array. The high collection efficiency enables the use of pulsed tunable lasers with low repetition rates (e.g., 20 Hz) instead of continuous wave (cw) lasers or very high repetition rate (e.g., MHz) lasers that are typically used as light sources for gas-phase fluorescence experiments on molecular ions. A hole has been drilled in the cylinder electrode so that a light pulse can interact with the ion cloud in the center of the trap. Simulations indicate that these modifications to the trap do not significantly affect the storage capability and the overall shape of the ion cloud. The overlap between the ion cloud and the laser light is basically 100%, and experimentally >50% of negatively charged chromophore ions are routinely photodepleted. The performance of the setup is illustrated based on fluorescence spectra of several laser dyes, and the quality of these spectra is comparable to those reported by other groups. Finally, by replacing the optical system with a channeltron detector, we demonstrate that the setup can also be used for gas-phase action spectroscopy where either depletion or fragmentation is monitored to provide an indirect measurement on the absorption spectrum of the ion.

  13. A cylindrical quadrupole ion trap in combination with an electrospray ion source for gas-phase luminescence and absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stockett, Mark H., E-mail: stockett@phys.au.dk; Houmøller, Jørgen; Støchkel, Kristian; Svendsen, Annette; Brøndsted Nielsen, Steen [Department of Physics and Astronomy, Aarhus University, Aarhus (Denmark)

    2016-05-15

    A relatively simple setup for collection and detection of light emitted from isolated photo-excited molecular ions has been constructed. It benefits from a high collection efficiency of photons, which is accomplished by using a cylindrical ion trap where one end-cap electrode is a mesh grid combined with an aspheric condenser lens. The geometry permits nearly 10% of the emitted light to be collected and, after transmission losses, approximately 5% to be delivered to the entrance of a grating spectrometer equipped with a detector array. The high collection efficiency enables the use of pulsed tunable lasers with low repetition rates (e.g., 20 Hz) instead of continuous wave (cw) lasers or very high repetition rate (e.g., MHz) lasers that are typically used as light sources for gas-phase fluorescence experiments on molecular ions. A hole has been drilled in the cylinder electrode so that a light pulse can interact with the ion cloud in the center of the trap. Simulations indicate that these modifications to the trap do not significantly affect the storage capability and the overall shape of the ion cloud. The overlap between the ion cloud and the laser light is basically 100%, and experimentally >50% of negatively charged chromophore ions are routinely photodepleted. The performance of the setup is illustrated based on fluorescence spectra of several laser dyes, and the quality of these spectra is comparable to those reported by other groups. Finally, by replacing the optical system with a channeltron detector, we demonstrate that the setup can also be used for gas-phase action spectroscopy where either depletion or fragmentation is monitored to provide an indirect measurement on the absorption spectrum of the ion.

  14. Application of structured illumination to gas phase thermometry using thermographic phosphor particles: a study for averaged imaging

    Science.gov (United States)

    Zentgraf, Florian; Stephan, Michael; Berrocal, Edouard; Albert, Barbara; Böhm, Benjamin; Dreizler, Andreas

    2017-07-01

    Structured laser illumination planar imaging (SLIPI) is combined with gas phase thermometry measurements using thermographic phosphor (TGP) particles. The technique is applied to a heated jet surrounded by a coflow which is operated at ambient temperature. The respective air flows are seeded with a powder of BaMgAl10O17:Eu2+ (BAM) which is used as temperature-sensitive gas phase tracer. Upon pulsed excitation in the ultraviolet spectral range, the temperature is extracted based on the two-color ratio method combined with SLIPI. The main advantage of applying the SLIPI approach to phosphor thermometry is the reduction of particle-to-particle multiple light scattering and diffuse wall reflections, yielding a more robust calibration procedure as well as improving the measurement accuracy, precision, and sensitivity. For demonstration, this paper focuses on sample-averaged measurements of temperature fields in a jet-in-coflow configuration. Using the conventional approach, which in contrast to SLIPI is based on imaging with an unmodulated laser light sheet, we show that for the present setup typically 40% of the recorded signal is affected by the contribution of multiply scattered photons. At locations close to walls even up to 75% of the apparent signal is due to diffuse reflection and wall luminescence of BAM sticking at the surface. Those contributions lead to erroneous temperature fields. Using SLIPI, an unbiased two-color ratio field is recovered allowing for two-dimensional mean temperature reconstructions which exhibit a more realistic physical behavior. This is in contrast to results deduced by the conventional approach. Furthermore, using the SLIPI approach it is shown that the temperature sensitivity is enhanced by a factor of up to 2 at 270 °C. Finally, an outlook towards instantaneous SLIPI phosphorescence thermometry is provided.

  15. Summary on experimental methods for statistical transient analysis of two-phase gas-liquid flow

    International Nuclear Information System (INIS)

    Delhaye, J.M.; Jones, O.C. Jr.

    1976-06-01

    Much work has been done in the study of two-phase gas-liquid flows. Although it has been recognized superficially that such flows are not homogeneous in general, little attention has been paid to the inherent discreteness of the two-phase systems. Only relatively recently have fluctuating characteristics of two-phase flows been studied in detail. As a result, new experimental devices and techniques have been developed for use in measuring quantities previously ignored. This report reviews and summarizes most of these methods in an effort to emphasize the importance of the fluctuating nature of these flows and as a guide to further research in this field

  16. Quantum phase space for an ideal relativistic gas in d spatial dimensions

    International Nuclear Information System (INIS)

    Hayashi, M.; Vera Mendoza, H.

    1992-01-01

    We present the closed formula for the d-dimensional invariant phase-space integral for an ideal relativistic gas in an exact integral form. In the particular cases of the nonrelativistic and the extreme relativistic limits the phase-space integrals are calculated analytically. Then we consider the d-dimensional invariant phase space with quantum statistic and derive the cluster decomposition for the grand canonical and canonical partition functions as well as for the microcanonical and grand microcanonical densities of states. As a showcase, we consider the black-body radiation in d dimensions (Author)

  17. Growth of thin SiC films on Si single crystal wafers with a microwave excited plasma of methane gas

    DEFF Research Database (Denmark)

    Dhiman, Rajnish; Morgen, Per

    2013-01-01

    Wehave studied the growth and properties of SiC films on Siwafers, under ultrahigh vacuumbackground con- ditions, using a remote-, microwave excited,methane plasma as a source of active carbon and hydrogen,while the Si substrates were held at a temperature of near 700 °C. The reaction is diffusio......Wehave studied the growth and properties of SiC films on Siwafers, under ultrahigh vacuumbackground con- ditions, using a remote-, microwave excited,methane plasma as a source of active carbon and hydrogen,while the Si substrates were held at a temperature of near 700 °C. The reaction...... lowdensity of these, and are otherwise very uniform and poly- crystalline. They are characterized with scanning electron microscopy, atomic force microscopy, X-ray photo- electron spectroscopy, X-ray diffraction, and hardnessmeasurements....

  18. Comprehensive Analysis of the Gas- and Particle-Phase Products of VOC Oxidation

    Science.gov (United States)

    Bakker-Arkema, J.; Ziemann, P. J.

    2017-12-01

    Controlled environmental chamber studies are important for determining atmospheric reaction mechanisms and gas and aerosol products formed in the oxidation of volatile organic compounds (VOCs). Such information is necessary for developing detailed chemical models for use in predicting the atmospheric fate of VOCs and also secondary organic aerosol (SOA) formation. However, complete characterization of atmospheric oxidation reactions, including gas- and particle-phase product yields, and reaction branching ratios, are difficult to achieve. In this work, we investigated the reactions of terminal and internal alkenes with OH radicals in the presence of NOx in an attempt to fully characterize the chemistry of these systems while minimizing and accounting for the inherent uncertainties associated with environmental chamber experiments. Gas-phase products (aldehydes formed by alkoxy radical decomposition) and particle-phase products (alkyl nitrates, β-hydroxynitrates, dihydroxynitrates, 1,4-hydroxynitrates, 1,4-hydroxycarbonyls, and dihydroxycarbonyls) formed through pathways involving addition of OH to the C=C double bond as well as H-atom abstraction were identified and quantified using a suite of analytical techniques. Particle-phase products were analyzed in real time with a thermal desorption particle beam mass spectrometer; and off-line by collection onto filters, extraction, and subsequent analysis of functional groups by derivatization-spectrophotometric methods developed in our lab. Derivatized products were also separated by liquid chromatography for molecular quantitation by UV absorbance and identification using chemical ionization-ion trap mass spectrometry. Gas phase aldehydes were analyzed off-line by collection onto Tenax and a 5-channel denuder with subsequent analysis by gas chromatography, or by collection onto DNPH-coated cartridges and subsequent analysis by liquid chromatography. The full product identification and quantitation, with careful

  19. Diffusion Monte Carlo simulations of gas phase and adsorbed D2-(H2)n clusters

    Science.gov (United States)

    Curotto, E.; Mella, M.

    2018-03-01

    We have computed ground state energies and analyzed radial distributions for several gas phase and adsorbed D2(H2)n and HD(H2)n clusters. An external model potential designed to mimic ionic adsorption sites inside porous materials is used [M. Mella and E. Curotto, J. Phys. Chem. A 121, 5005 (2017)]. The isotopic substitution lowers the ground state energies by the expected amount based on the mass differences when these are compared with the energies of the pure clusters in the gas phase. A similar impact is found for adsorbed aggregates. The dissociation energy of D2 from the adsorbed clusters is always much higher than that of H2 from both pure and doped aggregates. Radial distributions of D2 and H2 are compared for both the gas phase and adsorbed species. For the gas phase clusters, two types of hydrogen-hydrogen interactions are considered: one based on the assumption that rotations and translations are adiabatically decoupled and the other based on nonisotropic four-dimensional potential. In the gas phase clusters of sufficiently large size, we find the heavier isotopomer more likely to be near the center of mass. However, there is a considerable overlap among the radial distributions of the two species. For the adsorbed clusters, we invariably find the heavy isotope located closer to the attractive interaction source than H2, and at the periphery of the aggregate, H2 molecules being substantially excluded from the interaction with the source. This finding rationalizes the dissociation energy results. For D2-(H2)n clusters with n ≥12 , such preference leads to the desorption of D2 from the aggregate, a phenomenon driven by the minimization of the total energy that can be obtained by reducing the confinement of (H2)12. The same happens for (H2)13, indicating that such an effect may be quite general and impact on the absorption of quantum species inside porous materials.

  20. The Genealogical Tree of Ethanol: Gas-phase Formation of Glycolaldehyde, Acetic Acid, and Formic Acid

    Science.gov (United States)

    Skouteris, Dimitrios; Balucani, Nadia; Ceccarelli, Cecilia; Vazart, Fanny; Puzzarini, Cristina; Barone, Vincenzo; Codella, Claudio; Lefloch, Bertrand

    2018-02-01

    Despite the harsh conditions of the interstellar medium, chemistry thrives in it, especially in star-forming regions where several interstellar complex organic molecules (iCOMs) have been detected. Yet, how these species are synthesized is a mystery. The majority of current models claim that this happens on interstellar grain surfaces. Nevertheless, evidence is mounting that neutral gas-phase chemistry plays an important role. In this paper, we propose a new scheme for the gas-phase synthesis of glycolaldehyde, a species with a prebiotic potential and for which no gas-phase formation route was previously known. In the proposed scheme, the ancestor is ethanol and the glycolaldehyde sister species are acetic acid (another iCOM with unknown gas-phase formation routes) and formic acid. For the reactions of the new scheme with no available data, we have performed electronic structure and kinetics calculations deriving rate coefficients and branching ratios. Furthermore, after a careful review of the chemistry literature, we revised the available chemical networks, adding and correcting several reactions related to glycolaldehyde, acetic acid, and formic acid. The new chemical network has been used in an astrochemical model to predict the abundance of glycolaldehyde, acetic acid, and formic acid. The predicted abundance of glycolaldehyde depends on the ethanol abundance in the gas phase and is in excellent agreement with the measured one in hot corinos and shock sites. Our new model overpredicts the abundance of acetic acid and formic acid by about a factor of 10, which might imply a yet incomplete reaction network.

  1. Atmospheric-pressure dielectric barrier discharge with capillary injection for gas-phase nanoparticle synthesis

    International Nuclear Information System (INIS)

    Ghosh, Souvik; Liu, Tianqi; Bilici, Mihai; Cole, Jonathan; Huang, I-Min; Sankaran, R Mohan; Staack, David; Mariotti, Davide

    2015-01-01

    We present an atmospheric-pressure dielectric barrier discharge (DBD) reactor for gas-phase nanoparticle synthesis. Nickel nanoparticles are synthesized by homogenous nucleation from nickelocene vapor and characterized online by aerosol mobility measurements. The effects of residence time and precursor concentration on particle growth are studied. We find that narrower distributions of smaller particles are produced by decreasing the precursor concentration, in agreement with vapor nucleation theory, but larger particles and aggregates form at higher gas flow rates where the mean residence time should be reduced, suggesting a cooling effect that leads to enhanced particle nucleation. In comparison, incorporating a capillary gas injector to alter the velocity profile is found to significantly reduce particle size and agglomeration. These results suggest that capillary gas injection is a better approach to decreasing the mean residence time and narrowing the residence time distribution for nanoparticle growth by producing a sharp and narrow velocity profile. (paper)

  2. Visualization for gas-liquid two-phase flow using wire mesh tomography

    International Nuclear Information System (INIS)

    Motegi, Yuichi; Wanjiraniran, Weerin; Kikura, Hiroshige; Aritomi, Masanori; Yamauchi, Toyoaki

    2003-01-01

    Wire Mesh Tomography (WMT), which is system to measure two-phase flow, has been developed in our laboratory. Measurement principle of WMT is detecting conductivity difference between gas and liquid. WMT measures void fraction as raw date, and calculates gas velocity and bubble volume etc. In this paper, this measurement technique was applied to vertical circular pipe of 50 mm diameter and about 7 m heights. New Wire Mesh Sensor (WMS), which is measurement part of WMT, for circular pipe, have been made. When experiment was performed, superficial gas and water velocity. The effect of each flow parameter was found for void fraction, true gas velocity and bubble volume and the results was in good agreement with the past research, qualitatively. (author)

  3. Zpif's law in the liquid gas phase transition of nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Y.G. [China Center of Advanced Science and Technology (CCAST), Beijing, BJ (China). World Lab.; Shanghai Institute of Nuclear Research, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China)

    1999-12-01

    Zpif's law in the field of linguistics is tested in the nuclear disassembly within the framework of isospin dependent lattice gas model. It is found that the average cluster charge (or mass) of rank n in the charge (or mass) list shows exactly inversely to its rank, i.e., there exists Zpif's law, at the phase transition temperature. This novel criterion shall be helpful to search the nuclear liquid gas phase transition experimentally and theoretically. In addition, the finite size scaling of the effective phase transition temperature at which the Zpif's law appears is studied for several systems with different mass and the critical exponents of {nu} and {beta} are tentatively extracted. (orig.)

  4. Recent progress of chiral stationary phases for separation of enantiomers in gas chromatography.

    Science.gov (United States)

    Xie, Sheng-Ming; Yuan, Li-Ming

    2017-01-01

    Chromatography techniques based on chiral stationary phases are widely used for the separation of enantiomers. In particular, gas chromatography has developed rapidly in recent years due to its merits such as fast analysis speed, lower consumption of stationary phases and analytes, higher column efficiency, making it a better choice for chiral separation in diverse industries. This article summarizes recent progress of novel chiral stationary phases based on cyclofructan derivatives and chiral porous materials including chiral metal-organic frameworks, chiral porous organic frameworks, chiral inorganic mesoporous materials, and chiral porous organic cages in gas chromatography, covering original research papers published since 2010. The chiral recognition properties and mechanisms of separation toward enantiomers are also introduced. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Experimental redetermination of the gas-phase enthalpy of formation of ethyl 2-thiophenecarboxylate

    International Nuclear Information System (INIS)

    Santos, Ana Filipa L.O.M.; Ribeiro da Silva, Manuel A.V.

    2013-01-01

    The condensed phase standard (p° = 0.1 MPa) molar enthalpy of formation of ethyl-2-thiophenecarboxylate was derived from the remeasured standard molar energy of combustion, in oxygen, at T = 298.15 K, by rotating bomb combustion calorimetry and the standard molar enthalpy of vaporization, at T = 298.15 K, remeasured by Calvet microcalorimetry. Combining these two values, the following enthalpy of formation in the gas phase, at T = 298.15 K, was then derived for ethyl-2-thiophenecarboxylate: −(277.7 ± 2.9) kJ · mol −1 . The calculated gas-phase enthalpy of formation of the title compound, through the G3(MP2)//B3LYP approach was found to be 278.9 kJ · mol −1 , in excellent agreement with the experimental measured value

  6. Effect of duty-cycles on the air plasma gas-phase of dielectric barrier discharges

    Science.gov (United States)

    Barni, R.; Biganzoli, I.; Dell'Orto, E. C.; Riccardi, C.

    2015-10-01

    An experimental investigation concerning the effects of a duty-cycle in the supply of a dielectric barrier discharge in atmospheric pressure air has been performed. Electrical characteristics of the discharge have been measured, focusing mainly on the statistical properties of the current filaments and on dielectric surface charging, both affected by the frequent repetition of breakdown imposed by the duty-cycle. Information on the gas-phase composition was gathered too. In particular, a strong enhancement in the ozone formation rate is observed when suitable long pauses separate the active discharge phases. A simulation of the chemical kinetics in the gas-phase, based on a simplified discharge modeling, is briefly described in order to shed light on the observed increase in ozone production. The effect of a duty-cycle on surface modification of polymeric films in order to increase their wettability has been investigated too.

  7. Fluid Phase Separation (FPS) experiment for flight on a space shuttle Get Away Special (GAS) canister

    Science.gov (United States)

    Peters, Bruce; Wingo, Dennis; Bower, Mark; Amborski, Robert; Blount, Laura; Daniel, Alan; Hagood, Bob; Handley, James; Hediger, Donald; Jimmerson, Lisa

    1990-01-01

    The separation of fluid phases in microgravity environments is of importance to environmental control and life support systems (ECLSS) and materials processing in space. A successful fluid phase separation experiment will demonstrate a proof of concept for the separation technique and add to the knowledge base of material behavior. The phase separation experiment will contain a premixed fluid which will be exposed to a microgravity environment. After the phase separation of the compound has occurred, small samples of each of the species will be taken for analysis on the Earth. By correlating the time of separation and the temperature history of the fluid, it will be possible to characterize the process. The experiment has been integrated into space available on a manifested Get Away Special (GAS) experiment, CONCAP 2, part of the Consortium for Materials Complex Autonomous Payload (CAP) Program, scheduled for STS-42. The design and the production of a fluid phase separation experiment for rapid implementation at low cost is presented.

  8. Temperature dependence of the particle/gas partition coefficient: An application to predict indoor gas-phase concentrations of semi-volatile organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Wenjuan, E-mail: Wenjuan.Wei@cstb.fr [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); Mandin, Corinne [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); Blanchard, Olivier [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Mercier, Fabien [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Pelletier, Maud [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Le Bot, Barbara [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); and others

    2016-09-01

    The indoor gas-phase concentrations of semi-volatile organic compounds (SVOCs) can be predicted from their respective concentrations in airborne particles by applying the particle/gas partitioning equilibrium. The temperature used for partitioning is often set to 25 °C. However, indoor temperatures frequently differ from this reference value. This assumption may result in errors in the predicted equilibrium gas-phase SVOC concentrations. To improve the prediction model, the temperature dependence of the particle/gas partition coefficient must be addressed. In this paper, a theoretical relationship between the particle/gas partition coefficient and temperature was developed based on the SVOC absorptive mechanism. The SVOC particle/gas partition coefficients predicted by employing the derived theoretical relationship agree well with the experimental data retrieved from the literature (R > 0.93). The influence of temperature on the equilibrium gas-phase SVOC concentration was quantified by a dimensionless analysis of the derived relationship between the SVOC particle/gas partition coefficient and temperature. The predicted equilibrium gas-phase SVOC concentration decreased by between 31% and 53% when the temperature was lowered by 6 °C, while it increased by up to 750% when the indoor temperature increased from 15 °C to 30 °C. - Highlights: • A theoretical relationship between K{sub p} and temperature was developed. • The relationship was based on the SVOC absorptive mechanism. • The temperature impact was quantified by a dimensionless analysis.

  9. Gas phase chemical studies of superheavy elements using the Dubna gas-filled recoil separator - Stopping range determination

    International Nuclear Information System (INIS)

    Wittwer, D.; Abdullin, F.Sh.; Aksenov, N.V.; Albin, Yu.V.; Bozhikov, G.A.; Dmitriev, S.N.; Dressler, R.; Eichler, R.; Gaeggeler, H.W.; Henderson, R.A.; Huebener, S.; Kenneally, J.M.; Lebedev, V.Ya.; Lobanov, Yu.V.; Moody, K.J.; Oganessian, Yu.Ts.; Petrushkin, O.V.; Polyakov, A.N.; Piguet, D.; Rasmussen, P.

    2010-01-01

    Currently, gas phase chemistry experiments with heaviest elements are usually performed with the gas-jet technique with the disadvantage that all reaction products are collected in a gas-filled thermalisation chamber adjacent to the target. The incorporation of a physical preseparation device between target and collection chamber opens up the perspective to perform new chemical studies. But this approach requires detailed knowledge of the stopping force (STF) of the heaviest elements in various materials. Measurements of the energy loss of mercury (Hg), radon (Rn), and nobelium (No) in Mylar and argon (Ar) were performed at low kinetic energies of around (40-270) keV per nucleon. The experimentally obtained values were compared with STF calculations of the commonly used program for calculating stopping and ranges of ions in matter (SRIM). Using the obtained data points an extrapolation of the STF up to element 114, eka-lead, in the same stopping media was carried out. These estimations were applied to design and to perform a first chemical experiment with a superheavy element behind a physical preseparator using the nuclear fusion reaction 244 Pu( 48 Ca; 3n) 289 114. One decay chain assigned to an atom of 285 112, the α-decay product of 289 114, was observed.

  10. Axial dispersion of gas and solid phases in a gas—solid packed column at trickle flow

    NARCIS (Netherlands)

    Roes, A.W.M.; van Swaaij, Willibrordus Petrus Maria

    1979-01-01

    Axial dispersion of gas and solid phases in a gas—solid packed column at trickle flow, a promising new countercurrent operation, was evaluated using residence time distribution (RTD) experiments. The column was packed with dumped Pall rings, the gas phase was air at ambient conditions and the solid

  11. Heavy haze in winter Beijing driven by fast gas phase oxidation

    Science.gov (United States)

    Lu, K.; Tan, Z.; Wang, H.; Li, X.; Wu, Z.; Chen, Q.; Wu, Y.; Ma, X.; Liu, Y.; Chen, X.; Shang, D.; Dong, H.; Zeng, L.; Shao, M.; Hu, M.; Fuchs, H.; Novelli, A.; Broch, S.; Hofzumahaus, A.; Holland, F.; Rohrer, F.; Bohn, B.; Georgios, G.; Schmitt, S. H.; Schlag, P.; Kiendler-Scharr, A.; Wahner, A.; Zhang, Y.

    2017-12-01

    Heavy haze conditions were frequently presented in the airsheds of Beijing and surrounding areas, especially during winter time. To explore the trace gas oxidation and the subsequent formation of aerosols, a comprehensive field campaign was performed at a regional site (in the campus of University of Chinese Academy of Science, UCAS) in Beijing winter 2016. Serious haze pollution processes were often observed with the fast increase of inorganic salt (especially nitrate) and these pollutions were always associated with enhanced humidity and the concentrations of PAN (PeroxyAcyl Nitrates) which is normally a marker of gas phase oxidations from NOx and VOCs. Moreover, based on the measurements of OH, HO2, RO2, total OH reactivity, N2O5, NO, NO2, SO2, particle concentrations/distributions/chemical compositions, and meteorological parameters, the gas phase oxidation rates that leads to the formation of sulfate, nitrate and secondary organic aerosols were estimated. These determined formation rates were clearly enhanced by several folds during pollution episodes compared to that of the clean air masses. Preliminary analysis result showed that the gas phase formation potential of nitrate and secondary organic aerosols were larger than the observed concentrations of nitrate and SOA of which the excess production may be explained by deposition and dilution.

  12. Gas-phase advanced oxidation as an integrated air pollution control technique

    Directory of Open Access Journals (Sweden)

    Getachew A. Adnew

    2016-03-01

    Full Text Available Gas-phase advanced oxidation (GPAO is an emerging air cleaning technology based on the natural self-cleaning processes that occur in the Earth’s atmosphere. The technology uses ozone, UV-C lamps and water vapor to generate gas-phase hydroxyl radicals that initiate oxidation of a wide range of pollutants. In this study four types of GPAO systems are presented: a laboratory scale prototype, a shipping container prototype, a modular prototype, and commercial scale GPAO installations. The GPAO systems treat volatile organic compounds, reduced sulfur compounds, amines, ozone, nitrogen oxides, particles and odor. While the method covers a wide range of pollutants, effective treatment becomes difficult when temperature is outside the range of 0 to 80 °C, for anoxic gas streams and for pollution loads exceeding ca. 1000 ppm. Air residence time in the system and the rate of reaction of a given pollutant with hydroxyl radicals determine the removal efficiency of GPAO. For gas phase compounds and odors including VOCs (e.g. C6H6 and C3H8 and reduced sulfur compounds (e.g. H2S and CH3SH, removal efficiencies exceed 80%. The method is energy efficient relative to many established technologies and is applicable to pollutants emitted from diverse sources including food processing, foundries, water treatment, biofuel generation, and petrochemical industries.

  13. Gas-phase ion-molecular reactions of free ethylsilylic ions with ethylene

    International Nuclear Information System (INIS)

    Shchukin, E.V.; Kochina, T.A.; Sinotova, E.N.; Ignat'ev, I.S.

    2001-01-01

    Interaction of ethylsilylic ions, resulting from β-decay of tritium compounds, with ethylene in gaseous phase was studied by radiochemical method. The interaction occurs via formation of excited adduct C 4 H 11 Si + , its structure presenting a complex of ethylsilylic cation and ethylene. In the course of the complex lifetime isotopic exchange between the cation tritium atoms and proton of ethylene takes place along with isomerization of ethylsilylic cation into dimethylsilylic one. Decomposition of the complex gives rise largely to labeled ethylene formation [ru

  14. Investigation of gas-phase decontamination of internally radioactively contaminated gaseous diffusion process equipment and piping

    International Nuclear Information System (INIS)

    Bundy, R.D.; Munday, E.B.

    1991-01-01

    Construction of the gaseous diffusion plants (GDPs) was begun during World War 2 to produce enriched uranium for defense purposes. These plants, which utilized UF 6 gas, were used primarily for this purpose through 1964. From 1959 through 1968, production shifted primarily to uranium enrichment to supply the nuclear power industry. Additional UF 6 -handling facilities were built in feed and fuel-processing plants associated with the uranium enrichment process. Two of the five process buildings at Oak ridge were shut down in 1964. Uranium enrichment activities at Oak Ridge were discontinued altogether in 1985. In 1987, the Department of Energy (DOE) decided to proceed with a permanent shutdown of the Oak Ridge Gaseous Diffusion Plant (ORGDP). DOE intends to begin decommissioning and decontamination (D ampersand D) of ORGDP early in the next century. The remaining two GDPs are expected to be shut down during the next 10 to 40 years and will also require D ampersand D, as will the other UF 6 -handling facilities. This paper presents an investigation of gas- phase decontamination of internally radioactively contaminated gaseous diffusion process equipment and piping using powerful fluorinating reagents that convert nonvolatile uranium compounds to volatile UF 6 . These reagents include ClF 3 , F 2 , and other compounds. The scope of D ampersand D at the GDPs, previous work of gas-phase decontamination, four concepts for using gas-phase decontamination, plans for further study of gas-phase decontamination, and the current status of this work are discussed. 13 refs., 15 figs

  15. Transport of Gas Phase Radionuclides in a Fractured, Low-Permeability Reservoir

    Science.gov (United States)

    Cooper, C. A.; Chapman, J.

    2001-12-01

    The U.S. Atomic Energy Commission (predecessor to the Department of Energy, DOE) oversaw a joint program between industry and government in the 1960s and 1970s to develop technology to enhance production from low-permeability gas reservoirs using nuclear stimulation rather than conventional means (e.g., hydraulic and/or acid fracturing). Project Rio Blanco, located in the Piceance Basin, Colorado, was the third experiment under the program. Three 30-kiloton nuclear explosives were placed in a 2134 m deep well at 1780, 1899, and 2039 m below the land surface and detonated in May 1973. Although the reservoir was extensively fractured, complications such as radionuclide contamination of the gas prevented production and subsequent development of the technology. Two-dimensional numerical simulations were conducted to identify the main transport processes that have occurred and are currently occurring in relation to the detonations, and to estimate the extent of contamination in the reservoir. Minor modifications were made to TOUGH2, the multiphase, multicomponent reservoir simulator developed at Lawrence Berkeley National Laboratories. The simulator allows the explicit incorporation of fractures, as well as heat transport, phase change, and first order radionuclide decay. For a fractured two-phase (liquid and gas) reservoir, the largest velocities are of gases through the fractures. In the gas phase, tritium and one isotope of krypton are the principle radionuclides of concern. However, in addition to existing as a fast pathway, fractures also permit matrix diffusion as a retardation mechanism. Another retardation mechanism is radionuclide decay. Simulations show that incorporation of fractures can significantly alter transport rates, and that radionuclides in the gas phase can preferentially migrate upward due to the downward gravity drainage of liquid water in the pores. This project was funded by the National Nuclear Security Administration, Nevada Operations Office

  16. Fundamental research of two-phase flows with high liquid/gas density ratios

    International Nuclear Information System (INIS)

    Mishima, Kaichiro; Hibiki, Takashi; Saito, Yasushi; Tobita, Yoshiharu; Konishi, Kensuke; Suzuki, Tohru

    2000-07-01

    In order to analyze the boiling of a fuel-steel mixture pool formed during the core disruptive accident in a fast breeder reactor, it is important to understand the flow characteristics of gas-liquid two-phase pools containing molten reactor materials. Since the liquid/gas density ratio is high, the characteristics of such two-phase flows may differ from those of ordinary flows such as water/air flow. In this study, as a fundamental research of two-phase flows with a high liquid/gas density ratio, the experiments were performed to visualize and measure molten metal (lead-bismuth)/nitrogen gas two-phase flows using a neutron radiography technique. From these experiments, fundamental data such as bubble shapes, void fractions and liquid velocity fields were obtained. In addition, the momentum exchange model of SIMMER-III, which has been developed by JNC, was assessed and improved using the experimental data. In the visualization by neutron radiography, it was found that deformed ellipsoidal bubbles could be seen with smaller gas flux or lower void fractions, and spherical cap bubbles could be seen with larger gas flux or higher void fractions. In addition, a correlation applicable to SIMMER-III was proposed through a comparison between the experimental data and traditional empirical correlations. Furthermore, a visualization experiment using gold-cadmium tracer particles showed that the image processing technique used in the quantification of void fractions is applicable to the measurement of the liquid velocity fields. On the other hand, in the analysis by SIMMER-III, it was confirmed that the original momentum exchange model was appropriate for ellipsoidal bobby flows and that the accuracy of SIMMER-III for cap bubbly flows was much improved with the proposed correlation. Moreover, a new procedure, in which the appropriate drag coefficient could be automatically selected according to bubble shape, was developed. The SIMMER-III code improved through this study can

  17. 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

    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...... change material, mainly occurs after the fueling is completed, resulting in a higher hydrogen peak temperature inside the tank and a lower fuelled mass than a gas-cooled system. Such a mass reduction accounts for 12% with respect to the case of a standard tank system fuelled at -40 °C....

  18. 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....

  19. Shear viscosity of neutron-rich nucleonic matter near its liquid–gas phase transition

    International Nuclear Information System (INIS)

    Xu, Jun; Chen, Lie-Wen; Ko, Che Ming; Li, Bao-An; Ma, Yu Gang

    2013-01-01

    Within a relaxation time approach using free nucleon–nucleon cross sections modified by the in-medium nucleon masses that are determined from an isospin- and momentum-dependent effective nucleon–nucleon interaction, we investigate the specific shear viscosity (η/s) of neutron-rich nucleonic matter near its liquid–gas phase transition. It is found that as the nucleonic matter is heated at fixed pressure or compressed at fixed temperature, its specific shear viscosity shows a valley shape in the temperature or density dependence, with the minimum located at the boundary of the phase transition. Moreover, the value of η/s drops suddenly at the first-order liquid–gas phase transition temperature, reaching as low as 4–5 times the KSS bound of ℏ/4π. However, it varies smoothly for the second-order liquid–gas phase transition. Effects of the isospin degree of freedom and the nuclear symmetry energy on the value of η/s are also discussed

  20. Laboratory investigations of the alpha-pinene/ozone gas-phase reaction

    International Nuclear Information System (INIS)

    Benner, C.L.

    1985-01-01

    In order to provide more insight into terpene photooxidation or ozonolysis reaction mechanisms, a radiotracer technique was developed. This technique was applied to an investigation of the 14 C-alpha-pinene/ozone reaction. In the first phase of the research, the carbon distribution at the conclusion of the ozonolysis reaction was determined by separating carbon-14-labelled gaseous products from labelled aerosols, and counting each phase by liquid scintillation methods. The resulting carbon balance was 38% to 60% filtered aerosols, 6% to 20% gas phase compounds, and 11% to 29% products absorbed on the reaction chamber walls. Recoveries of the alpha-pinene carbon-14 ranging from 79% to 97% were achieved using this method. The alpha-pinene concentrations in these experiments were close to ambient (1 part per billion), yet the carbon balance was similar to that observed at much higher concentrations (>1 part per million). In the second phase of the alpha-pinene study, both gas and aerosol products of the ozonolysis reaction were collected on cartridges impregnated with 2,4-dinitrophenylhydrazine, then analyzed by HPLC. In the final experiments, alpha-pinene aerosol was reacted with a silylating agent to improve the detection of organic acids and alcohols. The gas chromatographic/mass spectrometric analysis of the silylated aerosol products showed evidence of dimer/polymer formation occurring in the ozonolysis reaction

  1. Two-Phase Gas-Liquid Flow Structure Characteristics under Periodic Cross Forces Action

    Directory of Open Access Journals (Sweden)

    V. V. Perevezentsev

    2015-01-01

    Full Text Available The article presents a study of two-phase gas-liquid flow under the action of periodic cross forces. The work objective is to obtain experimental data for further analysis and have structure characteristics of the two-phase flow movement. For research, to obtain data without disturbing effect on the flow were used optic PIV (Particle Image Visualization methods because of their noninvasiveness. The cross forces influence was provided by an experimental stand design to change the angular amplitudes and the periods of channel movement cycle with two-phase flow. In the range of volume gas rates was shown a water flow rate versus the inclination angle of immovable riser section and the characteristic angular amplitudes and periods of riser section inclination cycle under periodic cross forces. Data on distribution of average water velocity in twophase flow in abovementioned cases were also obtained. These data allowed us to draw a conclusion that a velocity distribution depends on the angular amplitude and on the period of the riser section roll cycle. This article belongs to publications, which study two-phase flows with no disturbing effect on them. Obtained data give an insight into understanding a pattern of twophase gas-liquid flow under the action of periodic cross forces and can be used to verify the mathematical models of the CFD thermo-hydraulic codes. In the future, the work development expects taking measurements with more frequent interval in the ranges of angular amplitudes and periods of the channel movement cycle and create a mathematical model to show the action of periodic cross forces on two-phase gas-liquid flow.

  2. Determination of gas phase protein ion densities via ion mobility analysis with charge reduction.

    Science.gov (United States)

    Maisser, Anne; Premnath, Vinay; Ghosh, Abhimanyu; Nguyen, Tuan Anh; Attoui, Michel; Hogan, Christopher J

    2011-12-28

    We use a charge reduction electrospray (ESI) source and subsequent ion mobility analysis with a differential mobility analyzer (DMA, with detection via both a Faraday cage electrometer and a condensation particle counter) to infer the densities of single and multiprotein ions of cytochrome C, lysozyme, myoglobin, ovalbumin, and bovine serum albumin produced from non-denaturing (20 mM aqueous ammonium acetate) and denaturing (1 : 49.5 : 49.5, formic acid : methanol : water) ESI. Charge reduction is achieved through use of a Po-210 radioactive source, which generates roughly equal concentrations of positive and negative ions. Ions produced by the source collide with and reduce the charge on ESI generated drops, preventing Coulombic fissions, and unlike typical protein ESI, leading to gas-phase protein ions with +1 to +3 excess charges. Therefore, charge reduction serves to effectively mitigate any role that Coulombic stretching may play on the structure of the gas phase ions. Density inference is made via determination of the mobility diameter, and correspondingly the spherical equivalent protein volume. Through this approach it is found that for both non-denaturing and denaturing ESI-generated ions, gas-phase protein ions are relatively compact, with average densities of 0.97 g cm(-3) and 0.86 g cm(-3), respectively. Ions from non-denaturing ESI are found to be slightly more compact than predicted from the protein crystal structures, suggesting that low charge state protein ions in the gas phase are slightly denser than their solution conformations. While a slight difference is detected between the ions produced with non-denaturing and denaturing ESI, the denatured ions are found to be much more dense than those examined previously by drift tube mobility analysis, in which charge reduction was not employed. This indicates that Coulombic stretching is typically what leads to non-compact ions in the gas-phase, and suggests that for gas phase

  3. Laser diagnostics of a diamond depositing chemical vapour deposition gas-phase environment

    Energy Technology Data Exchange (ETDEWEB)

    Smith, James Anthony

    2002-07-01

    Studies have been carried out to understand the gas-phase chemistry underpinning diamond deposition in hot filament and DC-arcjet chemical vapour deposition (CVD) systems. Resonance enhanced Multiphoton lonisation (REMPI) techniques were used to measure the relative H atom and CH{sub 3} radical number densities and local gas temperatures prevalent in a hot filament reactor, operating on Ch{sub 4}/H{sub 2} and C{sub 2}H{sub 2}/H{sub 2} gas mixtures. These results were compared to a 3D-computer simulation, and hence provided an insight into the nature of the gas-phase chemistry with particular reference to C{sub 2}{yields}C{sub 1} species conversion. Similar experimental and theoretical studies were also carried out to explain the chemistry involved in NH{sub 3}/CH{sub 4}/H{sub 2} and N{sub 2}/CH{sub 4}/H{sub 2} gas mixtures. It was demonstrated that the reactive nature of the filament surface was dependent on the addition of NH{sub 3}, influencing atomic hydrogen production, and thus the H/C/N gas-phase chemistry. Studies of the DC-arcjet diamond CVD reactor consisted of optical emission spectroscopic studies of the plume during deposition from an Ar/H{sub 2}/CH{sub 4}/N{sub 2} gas mixture. Spatially resolved species emission intensity maps were obtained for C{sub 2}(d{yields}a), CN(B{yields}X) and H{sub {beta}} from Abel-inverted datasets. The C{sub 2}(d{yields}a) and CN(B{yields}X) emission intensity maps both show local maxima near the substrate surface. SEM and Laser Raman analyses indicate that N{sub 2} additions lead to a reduction in film quality and growth rate. Photoluminescence and SIMS analyses of the grown films provide conclusive evidence of nitrogen incorporation (as chemically bonded CN). Absolute column densities of C{sub 2}(a) in a DC-arcjet reactor operating on an Ar/H{sub 2}/CH{sub 4} gas mixture, were measured using Cavity ring down spectroscopy. Simulations of the measured C{sub 2}(v=0) transition revealed a rotational temperature of {approx

  4. Laser diagnostics of a diamond depositing chemical vapour deposition gas-phase environment

    International Nuclear Information System (INIS)

    Smith, James Anthony

    2002-01-01

    Studies have been carried out to understand the gas-phase chemistry underpinning diamond deposition in hot filament and DC-arcjet chemical vapour deposition (CVD) systems. Resonance enhanced Multiphoton lonisation (REMPI) techniques were used to measure the relative H atom and CH 3 radical number densities and local gas temperatures prevalent in a hot filament reactor, operating on Ch 4 /H 2 and C 2 H 2 /H 2 gas mixtures. These results were compared to a 3D-computer simulation, and hence provided an insight into the nature of the gas-phase chemistry with particular reference to C 2 →C 1 species conversion. Similar experimental and theoretical studies were also carried out to explain the chemistry involved in NH 3 /CH 4 /H 2 and N 2 /CH 4 /H 2 gas mixtures. It was demonstrated that the reactive nature of the filament surface was dependent on the addition of NH 3 , influencing atomic hydrogen production, and thus the H/C/N gas-phase chemistry. Studies of the DC-arcjet diamond CVD reactor consisted of optical emission spectroscopic studies of the plume during deposition from an Ar/H 2 /CH 4 /N 2 gas mixture. Spatially resolved species emission intensity maps were obtained for C 2 (d→a), CN(B→X) and H β from Abel-inverted datasets. The C 2 (d→a) and CN(B→X) emission intensity maps both show local maxima near the substrate surface. SEM and Laser Raman analyses indicate that N 2 additions lead to a reduction in film quality and growth rate. Photoluminescence and SIMS analyses of the grown films provide conclusive evidence of nitrogen incorporation (as chemically bonded CN). Absolute column densities of C 2 (a) in a DC-arcjet reactor operating on an Ar/H 2 /CH 4 gas mixture, were measured using Cavity ring down spectroscopy. Simulations of the measured C 2 (v=0) transition revealed a rotational temperature of ∼3300 K. This gas temperature is similar to that deduced from optical emission spectroscopy studies of the C 2 (d→a) transition. (author)

  5. Beyond phthalates: Gas phase concentrations and modeled gas/particle distribution of modern plasticizers

    Energy Technology Data Exchange (ETDEWEB)

    Schossler, Patricia [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54E, D-38108 Braunschweig (Germany); Institute of Environmental and Sustainable Chemistry, Technische Universitaet Braunschweig, Hagenring 30, D-38106 Braunschweig (Germany); Schripp, Tobias, E-mail: tobias.schripp@wki.fraunhofer.de [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54E, D-38108 Braunschweig (Germany); Salthammer, Tunga [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54E, D-38108 Braunschweig (Germany); Bahadir, Muefit [Institute of Environmental and Sustainable Chemistry, Technische Universitaet Braunschweig, Hagenring 30, D-38106 Braunschweig (Germany)

    2011-09-01

    The ongoing health debate about polymer plasticizers based on the esters of phthalic acid, especially di(2-ethylhexyl) phthalate (DEHP), has caused a trend towards using phthalates of lower volatility such as diisononyl phthalate (DINP) and towards other acid esters, such as adipates, terephthalates, citrates, etc. Probably the most important of these so-called 'alternative' plasticizers is diisononyl cyclohexane-1,2-dicarboxylate (DINCH). In the indoor environment, the continuously growing market share of this compound since its launch in 2002 is inter alia apparent from the increasing concentration of DINCH in settled house dust. From the epidemiological point of view there is considerable interest in identifying how semi-volatile organic compounds (SVOCs) distribute in the indoor environment, especially in air, airborne particles and sedimented house dust. This, however, requires reliable experimental concentration data for the different media and good measurements or estimates of their physical and chemical properties. This paper reports on air concentrations for DINP, DINCH, diisobutyl phthalate (DIBP), diisobutyl adipate (DIBA), diisobutyl succinate (DIBS) and diisobutyl glutarate (DIBG) from emission studies in the Field and Laboratory Emission Cell (FLEC). For DINP and DINCH it took about 50 days to reach the steady-state value: for four months no decay in the concentration could be observed. Moreover, vapor pressures p{sub 0} and octanol-air partitioning coefficients K{sub OA} were obtained for 37 phthalate and non-phthalate plasticizers from two different algorithms: EPI Suite and SPARC. It is shown that calculated gas/particle partition coefficients K{sub p} and fractions can widely differ due to the uncertainty in the predicted p{sub 0} and K{sub OA} values. For most of the investigated compounds reliable experimental vapor pressures are not available. Rough estimates can be obtained from the measured emission rate of the pure compound in a

  6. Fractionation of Hydrocarbons Between Oil and Gas Phases Fractionnement des hydrocarbures entre les phases huile et gaz

    Directory of Open Access Journals (Sweden)

    Ruffier-Meray V.

    2006-12-01

    Full Text Available The investigation of hydrocarbon fractionation between oil and gas phases is of interest for several purposes in reservoir exploitation. In reservoir geochemistry, the evolution of light hydrocarbon fractions of oils may explain some migration phenomena. In gas injection projects, the preferred dissolution of some components in gas may alter the composition as well as the properties of the oil. Underground gas storage in depleted oil reservoirs may also be concerned by these problems. Results of several IFP studies are described here to illustrate and to quantify the phenomenon. Two of them, using real reservoir fluids, concern reservoir geochemistry, while the third, which is a swelling test, aimed to study gas injection, investigated a synthetic reservoir fluid with hydrocarbon components up to C30. Two pieces of equipment were used: a sapphire cell with a maximum pressure rating of 400 bar and a high pressure apparatus called Hercule with a maximum pressure of 1500 bar. For each fluid, the saturation pressure was measured. For various pressure levels below saturation, the coexisting liquid and gas phases were sampled at constant pressure, and subsequently analyzed by gas chromatography. In the gas injection study, sampling was repeated with different quantities of injection gas. Compared to a n-paraffin with the same number of carbon atoms, aromatic hydrocarbons appear to stay preferentially in the liquid phase, as do cycloalkanes to a lesser extent. The gaseous phase is slightly enriched in isoalkanes. These fractionation effects are less pronounced near the critical region. These phenomena have been modeled with a cubic equation of state combined with a group contribution mixing rule. L'étude du fractionnement des hydrocarbures légers entre les phases gazeuses et liquides intéresse plusieurs domaines dans le cadre de l'exploitation des gisements. En géochimie de réservoir l'évolution de la composition de la fraction légère peut

  7. CFD simulation of gas and non-Newtonian fluid two-phase flow in anaerobic digesters.

    Science.gov (United States)

    Wu, Binxin

    2010-07-01

    This paper presents an Eulerian multiphase flow model that characterizes gas mixing in anaerobic digesters. In the model development, liquid manure is assumed to be water or a non-Newtonian fluid that is dependent on total solids (TS) concentration. To establish the appropriate models for different TS levels, twelve turbulence models are evaluated by comparing the frictional pressure drops of gas and non-Newtonian fluid two-phase flow in a horizontal pipe obtained from computational fluid dynamics (CFD) with those from a correlation analysis. The commercial CFD software, Fluent12.0, is employed to simulate the multiphase flow in the digesters. The simulation results in a small-sized digester are validated against the experimental data from literature. Comparison of two gas mixing designs in a medium-sized digester demonstrates that mixing intensity is insensitive to the TS in confined gas mixing, whereas there are significant decreases with increases of TS in unconfined gas mixing. Moreover, comparison of three mixing methods indicates that gas mixing is more efficient than mixing by pumped circulation while it is less efficient than mechanical mixing.

  8. Evaluation of gamma radiation effects on stationary phases using gas chromatografy

    International Nuclear Information System (INIS)

    Basso, M.A.; Collins, K.E.; Collins, C.H.

    1988-01-01

    The overall objetive of this project is a thorough study of the effect of gamma radiation on supported stationary phases used in packed-column gas chromatography. The phases studied were SP-2100 on Supelcoport and SE-30 on Chromsorb W. The fases were irradiated with cobalt-60 gamma rays to various doses and subsequently subjected to tests of extractability, termal stability and efficiency as a chromatographic column packing. Extraction tests indicate that low doses of radiation are sufficient to produce significant immobilization of these polymethylsilicones; that is, to produce chemical bonds between different polymer chains or between the stationary phase and the support. Thermal stability is also increased. The values calculated for the number of theoretical plates (n) and resolution (Rsub (s)) after analysis of four synthetic mixtures of organic compounds also increase, in most cases, indicating that the gamma irradiation has positively altered the behavior of these stationary phases. (author) [pt

  9. Measurement of turbulent diffusivity of both gas and liquid phases in quasi-2D two-phase flow

    International Nuclear Information System (INIS)

    Sato, Yoshifusa; Sadatomi, Michio; Kawahara, Akimaro

    1993-01-01

    The turbulent diffusion process has been studied experimentally by observing a tracer plume emitted continuously from a line source in a uniform, quasi-2D two-phase flow. The test section was a vertical, relatively narrow, concentric annular channel consisting of two large pipes. Air and water were used as the working fluids, and methane and acid organge II were used as tracers for the respective phases. Measurements of local, time-averaged tracer concentrations were made by means of a sampling method and image processing for bubbly flows and churn flows, and the turbulent diffusivity, the coefficient of turbulent diffusion, was determined from the concentration distributions measured. The diffusivities for the gas and liquid phases, ε DG and ε DL respectively, are presented and compared with each other in this paper. When a flow is bubbly, ε DG is close to or slightly smaller than ε DL . In a churn flow, on the contrary, ε DG is much greater than ε DL . Regarding bubbly flow, a plausible model on turbulent diffusivity of the liquid phase is presented and examined by the present data. (orig.)

  10. Gas-Phase Reaction Pathways and Rate Coefficients for the Dichlorosilane-Hydrogen and Trichlorosilane-Hydrogen Systems

    Science.gov (United States)

    Dateo, Christopher E.; Walch, Stephen P.

    2002-01-01

    As part of NASA Ames Research Center's Integrated Process Team on Device/Process Modeling and Nanotechnology our goal is to create/contribute to a gas-phase chemical database for use in modeling microelectronics devices. In particular, we use ab initio methods to determine chemical reaction pathways and to evaluate reaction rate coefficients. Our initial studies concern reactions involved in the dichlorosilane-hydrogen (SiCl2H2--H2) and trichlorosilane-hydrogen (SiCl2H-H2) systems. Reactant, saddle point (transition state), and product geometries and their vibrational harmonic frequencies are determined using the complete-active-space self-consistent-field (CASSCF) electronic structure method with the correlation consistent polarized valence double-zeta basis set (cc-pVDZ). Reaction pathways are constructed by following the imaginary frequency mode of the saddle point to both the reactant and product. Accurate energetics are determined using the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations (CCSD(T)) extrapolated to the complete basis set limit. Using the data from the electronic structure calculations, reaction rate coefficients are obtained using conventional and variational transition state and RRKM theories.

  11. Towards the Detection of Explosive Taggants: Microwave and Millimetre-Wave Gas-Phase Spectroscopies of 3-Nitrotoluene.

    Science.gov (United States)

    Roucou, Anthony; Kleiner, Isabelle; Goubet, Manuel; Bteich, Sabath; Mouret, Gael; Bocquet, Robin; Hindle, Francis; Meerts, W Leo; Cuisset, Arnaud

    2018-01-12

    The monitoring of gas-phase mononitrotoluenes is crucial for defence, civil security and environmental interests because they are used as taggant for TNT detection and in the manufacturing of industrial compounds such as dyestuffs. In this study, we have succeeded to measure and analyse at high-resolution a room temperature rotationally resolved millimetre-wave spectrum of meta-nitrotoluene (3-NT). Experimental and theoretical difficulties have been overcome, in particular, those related to the low vapour pressure of 3-NT and to the presence of a CH 3 internal rotation in an almost free rotation regime (V 3 =6.7659(24) cm -1 ). Rotational spectra have been recorded in the microwave and millimetre-wave ranges using a supersonic jet Fourier Transform microwave spectrometer (T rot <10 K) and a millimetre-wave frequency multiplication chain (T=293 K), respectively. Spectral analysis of pure rotation lines in the vibrational ground state and in the first torsional excited state supported by quantum chemistry calculations permits the rotational energy of the molecule, the hyperfine structure due to the 14 N nucleus, and the internal rotation of the methyl group to be characterised. A line list is provided for future in situ detection. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. MOLECULAR SPECTROSCPY AND REACTIONS OF ACTINIDES IN THE GAS PHASE AND CRYOGENIC MATRICES

    Energy Technology Data Exchange (ETDEWEB)

    Heaven, Michael C.; Gibson, John K.; Marcalo, Joaquim

    2009-02-01

    In this chapter we review the spectroscopic data for actinide molecules and the reaction dynamics for atomic and molecular actinides that have been examined in the gas phase or in inert cryogenic matrices. The motivation for this type of investigation is that physical properties and reactions can be studied in the absence of external perturbations (gas phase) or under minimally perturbing conditions (cryogenic matrices). This information can be compared directly with the results from high-level theoretical models. The interplay between experiment and theory is critically important for advancing our understanding of actinide chemistry. For example, elucidation of the role of the 5f electrons in bonding and reactivity can only be achieved through the application of experimentally verified theoretical models. Theoretical calculations for the actinides are challenging due the large numbers of electrons that must be treated explicitly and the presence of strong relativistic effects. This topic has been reviewed in depth in Chapter 17 of this series. One of the goals of the experimental work described in this chapter has been to provide benchmark data that can be used to evaluate both empirical and ab initio theoretical models. While gas-phase data are the most suitable for comparison with theoretical calculations, there are technical difficulties entailed in generating workable densities of gas-phase actinide molecules that have limited the range of species that have been characterized. Many of the compounds of interest are refractory, and problems associated with the use of high temperature vapors have complicated measurements of spectra, ionization energies, and reactions. One approach that has proved to be especially valuable in overcoming this difficulty has been the use of pulsed laser ablation to generate plumes of vapor from refractory actinide-containing materials. The vapor is entrained in an inert gas, which can be used to cool the actinide species to room

  13. Chlorination of some eliphatic organic compounds in liquid and gas phase

    International Nuclear Information System (INIS)

    Hassan, A.A.

    1990-01-01

    The photochlorination of different organic compounds and the relative slectivities of different positions have been investigated in both gaseous and liquid phases at different temperatures. The results have shown that the relative selectivity generally decreased with increasing temperature and in the gas phase has a higher value. Polar solvents increase the selectivity relative to the chlorination of pure liquid phases. The differences in activation energy between two positions were much higher in the gas phases chlorination, relative to that in the liquid phase. It was also found that the functional groups have great influence on the rate of chlorine free radical attack on different positions, for example the electron withdrawing groups decreasing the selectivity on the first position, but the electron donating groups increase the selectivity on the first position, but the electron donating groups increase the selectivity on the first position. Furthermore it was found that the polar solvents, which stabilize the resonance between oxygen and carbon atoms, increases the selectivity on that position. 23 tabs.; 16 figs.; 50 refs

  14. Comprehensive Peptide Ion Structure Studies Using Ion Mobility Techniques: Part 3. Relating Solution-Phase to Gas-Phase Structures.

    Science.gov (United States)

    Kondalaji, Samaneh Ghassabi; Khakinejad, Mahdiar; Valentine, Stephen J

    2018-06-01

    Molecular dynamics (MD) simulations have been utilized to study peptide ion conformer establishment during the electrospray process. An explicit water model is used for nanodroplets containing a model peptide and hydronium ions. Simulations are conducted at 300 K for two different peptide ion charge configurations and for droplets containing varying numbers of hydronium ions. For all conditions, modeling has been performed until production of the gas-phase ions and the resultant conformers have been compared to proposed gas-phase structures. The latter species were obtained from previous studies in which in silico candidate structures were filtered according to ion mobility and hydrogen-deuterium exchange (HDX) reactivity matches. Results from the present study present three key findings namely (1) the evidence from ion production modeling supports previous structure refinement studies based on mobility and HDX reactivity matching, (2) the modeling of the electrospray process is significantly improved by utilizing initial droplets existing below but close to the calculated Rayleigh limit, and (3) peptide ions in the nanodroplets sample significantly different conformers than those in the bulk solution due to altered physicochemical properties of the solvent. Graphical Abstract ᅟ.

  15. Analyses of liquid-gas two-phase flow in fermentation tanks

    International Nuclear Information System (INIS)

    Toi, Takashi; Serizawa, Akimi; Takahashi, Osamu; Kawara, Zensaku; Gofuku, Akio; Kataoka, Isao.

    1993-01-01

    The understanding of two-phase flow is one of the important problems for both design and safety analyses of various engineering systems. For example, the flow conditions in beer fermentation tanks have an influence on the quality of production and productivity of tank. In this study, a two-dimensional numerical calculation code based on the one-pressure two-fluid model is developed to understand the circulation structure of low quality liquid-gas two-phase flows induced by bubble plume in a tank. (author)

  16. Fluorometric method for the determination of gas-phase hydrogen peroxide

    Science.gov (United States)

    Kok, Gregory L.; Lazrus, Allan L.

    1986-01-01

    The fluorometric gas-phase hydrogen peroxide procedure is based on the technique used by Lazrus et. al. for the determination of H2O2 in the liquid phase. The analytical method utilizes the reaction of H2O2 with horseradish peroxidase and p-hydroxphenylacetic acid (POPHA) to form the fluorescent dimer of POPHA. The analytical reaction responds stoichiometrically to both H2O2 and some organic hydroperoxides. To discriminate H2O2 from organic hydroperoxides, catalase is used to preferentially destroy H2O2. Using a dual-channel flow system the H2O2 concentration is determined by difference.

  17. Gas-Phase Molecular Dynamics: Theoretical Studies In Spectroscopy and Chemical Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Yu H. G.; Muckerman, J.T.

    2012-05-29

    The main goal of this program is the development and application of computational methods for studying chemical reaction dynamics and molecular spectroscopy in the gas phase. We are interested in developing rigorous quantum dynamics algorithms for small polyatomic systems and in implementing approximate approaches for complex ones. Particular focus is on the dynamics and kinetics of chemical reactions and on the rovibrational spectra of species involved in combustion processes. This research also explores the potential energy surfaces of these systems of interest using state-of-the-art quantum chemistry methods, and extends them to understand some important properties of materials in condensed phases and interstellar medium as well as in combustion environments.

  18. Optimization of phase analysis of refractory alloys in the gas-ion-reaction chamber

    International Nuclear Information System (INIS)

    Blumenkamp, H.J.; Hoven, H.; Koizlik, K.; Nickel, H.

    1980-04-01

    Reactor components outside the core which are under high thermal and mechanical stresses are made from refractory alloys. For basic research and for quality control, these materials are investigated by metallography, which is an independent group of characterization procedures as well as basis for many other methods. An important way of increasing the information about a material yielded by metallography is the expansions of phase contrast, in particular the phase contrasting in the gas-ion-reaction chamber. In this paper, the experimental procedure is described and the process of optimizing the procedure with respect to the Ni- and Fe-based refractory alloys examined in the IRW is discussed. (orig.) [de

  19. Probing Protein Structure and Folding in the Gas Phase by Electron Capture Dissociation

    Science.gov (United States)

    Schennach, Moritz; Breuker, Kathrin

    2015-07-01

    The established methods for the study of atom-detailed protein structure in the condensed phases, X-ray crystallography and nuclear magnetic resonance spectroscopy, have recently been complemented by new techniques by which nearly or fully desolvated protein structures are probed in gas-phase experiments. Electron capture dissociation (ECD) is unique among these as it provides residue-specific, although indirect, structural information. In this Critical Insight article, we discuss the development of ECD for the structural probing of gaseous protein ions, its potential, and limitations.

  20. Gas-phase infrared spectrum of phosphorus (III) oxycyanide, OPCN: experimental and theoretical investigations

    Science.gov (United States)

    Allaf, Abdul. W.; Kassem, M.; Alibrahim, M.; Boustani, Ihsan

    1999-03-01

    An attempt was made to observe the gas-phase infrared spectrum of Phosphorus (III) oxycyanide, OPCN for the first time. This molecule was produced by an on-line process using phosphorus (III) oxychloride, OPCl as precursor passed over heated AgCN. The products were characterised by the infrared spectra of their vapours. The low resolution gas-phase Fourier transform infrared spectrum shows two bands centered at 2165 and 1385 cm -1. These bands are assigned to, ν1 (CN stretch) and ν2 (OP stretch), respectively. Ab initio self-consistent-field (SCF) molecular orbital (MO) and Møller-Plesset second order perturbation theory (MP2) calculations were performed to determine the geometry, total energy and vibrational frequencies of OPCN.

  1. Gas-phase infrared spectrum of phosphorus (III) oxycyanide, OPCN: Experimental and theoretical and theoretical investigations

    International Nuclear Information System (INIS)

    Allaf, A.W.; Kassem, M.; Alibrahim, M.

    1999-01-01

    An attempt was made to observe the gas-phase infrared spectrum of phosphorus (III) oxycyanide, OPCN for the first time. This molecule was produced by on-line process using phosphorus (III) oxychloride, OPCI as precursor passed over heated Ag CN. The products were characterised by the infrared spectra of their vapours. The low resolution gas-phase Fourier transform infrared spectrum shows two bands at 2165 and 1385 cm -1 . These bands are assigned to ν 1 (C≡N stretch) and ν 2 (O=P stretch), respectively. Ab initio self-consistent-field (SCF) molecular orbital (MO) and Moeller - Plesset second order perturbation theory (MP2) calculations were performed to determine the geometry, total energy and vibrational frequencies of OPCN. (authors)

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  3. Effect of geometric parameters of liquid-gas separator units on phase separation performance

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Songping; Chen, Xueqing; Chen, Ying [Guangdong University of Technology, Seoul (China); Yang, Zhen [Tsinghua University, Beijing (China)

    2015-07-15

    Five liquid-gas separator units were designed and constructed based on a new concept of a validated high-performance condenser. Each separator unit consists of two united T-junctions and an apertured baffle. The separator units have different header diameters or different baffles with different diameters of the liquid-gas separation hole. The phase separation characteristics of the units were investigated at inlet air superficial velocities from 1.0m/s to 33.0m/s and water superficial velocities from 0.0015 m/s to 0..50 m/s. The experimental results showed that the liquid height, liquid flow rate through the separation hole, and liquid separation efficiency increased with increased header diameter and decreased diameter of the separation hole. The geometric structures of the separator units affected the phase separation characteristics by influencing the liquid height in the header and the liquid flow rate through the separation hole.

  4. Measurement of gas phase characteristics using new monofiber optical probes and real time signal processing

    International Nuclear Information System (INIS)

    Cartellier, A.

    1998-01-01

    Single optical or impedance phase detection probes are able to measure gas velocities provided that their sensitive length L is accurately known. In this paper, it is shown that L can be controlled during the manufacture of optical probes. Beside, for a probe geometry in the form of a cone + a cylinder + a cone, the corresponding rise time / velocity correlation becomes weakly sensitive to uncontrollable parameter such as the angle of impact on the interface. A real time signal processing performing phase detection as well as velocity measurements is described. Since its sensitivity to the operator inputs is less than the reproducibility of measurements, it is a fairly objective tool. Qualifications achieved in air/water flows with various optical probes demonstrate that the void fraction is detected with a relative error less than 10 %. For bubbly flows, the gas flux is accurate within ±10%, but this uncertainty increases when large bubbles are present in the flow. (author)

  5. Treatment of reduced sulphur compounds and SO2 by Gas Phase Advanced Oxidation

    DEFF Research Database (Denmark)

    Meusinger, Carl; Bluhme, Anders Brostrøm; Ingemar, Jonas L.

    2017-01-01

    Reduced sulphur compounds (RSCs) emitted from pig farms are a major problem for agriculture, due to their health and environmental impacts and foul odour. This study investigates the removal of RSCs, including H2S, and their oxidation product SO2 using Gas Phase Advanced Oxidation (GPAO). GPAO...... is a novel air cleaning technique which utilises accelerated atmospheric chemistry to oxidise pollutants before removing their oxidation products as particles. Removal efficiencies of 24.5% and 3.9% were found for 461 ppb of H2S and 714 ppb of SO2 in a laboratory system (volumetric flow Q = 75 m3/h......). A numerical model of the reactor system was developed to explore the basic features of the system; its output was in fair agreement with the experiment. The model verified the role of OH radicals in initiating the oxidation chemistry. All sulphur removed from the gas phase was detected as particulate matter...

  6. Photoelectron spectroscopy an introduction to ultraviolet photoelectron spectroscopy in the gas phase

    CERN Document Server

    Eland, J H D

    2013-01-01

    Photoelectron Spectroscopy: An Introduction to Ultraviolet Photoelectronspectroscopy in the Gas Phase, Second Edition Photoelectron Spectroscopy: An Introduction to Ultraviolet PhotoelectronSpectroscopy in the Gas Phase, Second Edition aims to give practical approach on the subject of photoelectron spectroscopy, as well as provide knowledge on the interpretation of the photoelectron spectrum. The book covers topics such as the principles and literature of photoelectron microscopy; the main features and analysis of photoelectron spectra; ionization techniques; and energies from the photoelectron spectra. Also covered in the book are topics suc as photoelectron band structure and the applications of photoelectron spectroscopy in chemistry. The text is recommended for students and practitioners of chemistry who would like to be familiarized with the concepts of photoelectron spectroscopy and its importance in the field.

  7. Online Measurements of Highly Oxidized Organics in the Gas and Particle phase during SOAS and SENEX

    Science.gov (United States)

    Lopez-Hilfiker, F.; Lee, B. H.; Mohr, C.; Ehn, M.; Rubach, F.; Mentel, T. F.; Kleist, E.; Thornton, J. A.

    2014-12-01

    We present measurements of a large suite of gas and particle phase organic compounds made with a Filter Inlet for Gas and AEROsol (FIGAERO) coupled to a high resolution time of flight chemical ionization mass spectrometer (HR-ToF-CIMS) developed at the University of Washington and with airborne HR-ToF-CIMS measurements. The FIGAERO instrument was deployed on the Jülich Plant Atmosphere Chamber to study α-pinene oxidation, and subsequently at the SMEAR II forest station in Hyytiälä, Finland and the SOAS ground site, in Brent Alabama. During the Southern Atmosphere Study, a gas-phase only version of the HR-ToF-CIMS was deployed on the NOAA WP-3 aircraft as part of SENEX. We focus here on highly oxygenated organic compounds derived from monoterpene oxidation detected both aloft during SENEX and at the ground-based site during SOAS. In both chamber and the atmosphere, many highly oxidized, low volatility compounds were observed in the gas and particles and many of the same compositions detected in the gas-phase were detected in the particles upon temperature programmed thermal desorption. The fraction of a given compound measured in the particle phase follows expected trends with elemental composition such as O/C ratios, but many compounds would not be well described by an absorptive partitioning model assuming unity activity coefficients. The detailed structure in the thermograms reveals a significant contribution from large molecular weight organics and/or oligomers in both chamber and ambient aerosol samples. Approximately 50% of the measured organics in the particle phase are associated with compounds having effective vapour pressures 4 or more orders of magnitude lower than commonly measured monoterpene oxidation products. We discuss the implications of these findings for measurements of gas-particle partitioning and for evaluating the contribution of monoterpene oxidation to organic aerosol formation and growth. We also use the aircraft measurements and a

  8. Improved gas installations and services. Phase 1: Analysis project. Part report

    International Nuclear Information System (INIS)

    Nielsen, K.J.

    1996-05-01

    As Danish gas companies receive a large number of complaints related to the installation and operation of gas installations it was suggested that a course for personnel should be established in order to raise the standard of services and installation requirements. The first phase of the described project was to evaluate the quality of the gas installers' services so as to determine which aspects of installation and services should be emphasized during such a course. Interviews were carried out and questionnaires (illustrated within the document) sent out to installaters etc. Recommendations include that the level of information given to customers should be raised, also in relation to maintenance, and that installation should be improved. Analyses of the degree of customers' satisfaction, of the nature of the quality of services etc. expected, subjects for further training in this area and details of the training system are dealt with

  9. Experimental studies on hydrogen isotopic deuterium from gas to liquid phase by catalytic exchange

    International Nuclear Information System (INIS)

    Luo Yangming; Wang Heyi; Liu Jun; Fu Zhonghua; Wang Changbin; Han Jun; Xia Xiulong; Tang Lei

    2005-01-01

    The experimental studies on hydrogen isotopic deuterium from gas to liquid phase were completed by mixed ratio 1:4 of Pt-SDB hydrophobic catalyst and hydrophilic packing. The influencing factors on number of transfer units (NTU) and transformation efficiencies of deuterium were researched. The results show that preferable NTU can be obtained by choosing suitable operational temperature and flux of exchange gas. The transformation rate increases with increasing liquid flux, but it cannot obviously be improved when liquid flux attains some level. The length of catalytic column has an obvious influence on transformation rate and 90% of transformation rate is obtained by 4 m column length at gas flux with 2 m 3 /h, liquid flux with 1-2 kg/h and 45 degree C. (author)

  10. Quantum mechanics of the fractional-statistics gas: Random-phase approximation

    International Nuclear Information System (INIS)

    Dai, Q.; Levy, J.L.; Fetter, A.L.; Hanna, C.B.; Laughlin, R.B.

    1992-01-01

    A description of the fractional-statistics gas based on the complete summation of Hartree, Fock, ladder and bubble diagrams is presented. The superfluid properties identified previously in the random-phase-approximation (RPA) calculation of Fetter, Hanna, and Laughlin [Phys. Rev. B 39, 9679 (1989)] are substantially confirmed. The discrepancy between the RPA sound speed and the Hartree-Fock bulk modulus is found to be eliminated. The unusual Hall-effect behavior is found to vanish for the Bose gas test case but not for the fractional-statistics gas, implying that it is physically correct. Excellent agreement is obtained with the collective-mode dispersion obtained numerically by Xie, He, and Das Sarma [Phys. Rev. Lett. 65, 649 (1990)

  11. Phase diagram and universality of the Lennard-Jones gas-liquid system

    KAUST Repository

    Watanabe, Hiroshi

    2012-01-01

    The gas-liquid phase transition of the three-dimensional Lennard-Jones particles system is studied by molecular dynamics simulations. The gas and liquid densities in the coexisting state are determined with high accuracy. The critical point is determined by the block density analysis of the Binder parameter with the aid of the law of rectilinear diameter. From the critical behavior of the gas-liquid coexisting density, the critical exponent of the order parameter is estimated to be β = 0.3285(7). Surface tension is estimated from interface broadening behavior due to capillary waves. From the critical behavior of the surface tension, the critical exponent of the correlation length is estimated to be ν = 0.63(4). The obtained values of β and ν are consistent with those of the Ising universality class. © 2012 American Institute of Physics.

  12. Excited argon 1s5 production in micro-hollow cathode discharges for use as potential rare gas laser sources

    Science.gov (United States)

    Peterson, Richard D.; Eshel, Ben; Rice, Christopher A.; Perram, Glen P.

    2018-02-01

    The diode-pumped rare gas laser (DPRGL) has been suggested as a potential high-gain, high-energy laser which requires densities on the order of 1013 cm-3 at pressures around 1 atmosphere for efficient operation. Argon 1s5 number densities have been measured in micro-hollow cathode discharges with electrode gaps of 127 and 254 μm and hole diameters from 100-400 μm. The dependency of the metastable argon (1s5) density on total gas pressure, electrode gap distance and hole diameter were explored. The measured densities were all in the range of 0.5 - 2 × 1013 cm-3 with the 400 μm hole diameters being the lowest.

  13. Source reconciliation of atmospheric gas-phase and particle-phase pollutants during a severe photochemical smog episode.

    Science.gov (United States)

    Schauer, James J; Fraser, Matthew P; Cass, Glen R; Simoneit, Bernd R T

    2002-09-01

    A comprehensive organic compound-based receptor model is developed that can simultaneously apportion the source contributions to atmospheric gas-phase organic compounds, semivolatile organic compounds, fine particle organic compounds, and fine particle mass. The model is applied to ambient data collected at four sites in the south coast region of California during a severe summertime photochemical smog episode, where the model determines the direct primary contributions to atmospheric pollutants from 11 distinct air pollution source types. The 11 sources included in the model are gasoline-powered motor vehicle exhaust, diesel engine exhaust, whole gasoline vapors, gasoline headspace vapors, organic solvent vapors, whole diesel fuel, paved road dust, tire wear debris, meat cooking exhaust, natural gas leakage, and vegetative detritus. Gasoline engine exhaust plus whole gasoline vapors are the predominant sources of volatile organic gases, while gasoline and diesel engine exhaust plus diesel fuel vapors dominate the emissions of semivolatile organic compounds from these sources during the episode studied at all four air monitoring sites. The atmospheric fine particle organic compound mass was composed of noticeable contributions from gasoline-powered motor vehicle exhaust, diesel engine exhaust, meat cooking, and paved road dust with smaller but quantifiable contributions from vegetative detritus and tire wear debris. In addition, secondary organic aerosol, which is formed from the low-vapor pressure products of gas-phase chemical reactions, is found to be a major source of fine particle organic compound mass under the severe photochemical smog conditions studied here. The concentrations of secondary organic aerosol calculated in the present study are compared with previous fine particle source apportionment results for less intense photochemical smog conditions. It is shown that estimated secondary organic aerosol concentrations correlate fairly well with the

  14. Conformational Study of DNA Sugars: from the Gas Phase to Solution

    Science.gov (United States)

    Uriarte, Iciar; Vallejo-López, Montserrat; Cocinero, Emilio J.; Corzana, Francisco; Davis, Benjamin G.

    2017-06-01

    Sugars are versatile molecules that play a variety of roles in the organism. For example, they are important in energy storage processes or as structural scaffolds. Here, we focus on the monosaccharide present in DNA by addressing the conformational and puckering properties in the gas phase of α- and β-methyl-2-deoxy-ribofuranoside and α- and β-methyl-2-deoxy-ribopiranoside. Other sugars have been previously studied in the gas phase The work presented here stems from a combination of chemical synthesis, ultrafast vaporization methods, supersonic expansions, microwave spectroscopy (both chirped-pulsed and Balle-Flygare cavity-based spectrometers) and NMR spectroscopy. Previous studies in the gas phase had been performed on 2-deoxyribose, but only piranose forms were detected. However, thanks to the combination of these techniques, we have isolated and characterized for the first time the conformational landscape of the sugar present in DNA in its biologically relevant furanose form. Our gas phase study serves as a probe of the conformational preferences of these biomolecules under isolation conditions. Thanks to the NMR experiments, we can characterize the favored conformations in solution and extract the role of the solvent in the structure and puckering of the monosaccharides. E. J. Cocinero, A. Lesarri, P. Écija, F. J. Basterretxea, J.-U. Grabow, J. A. Fernández, F. Castaño, Angew. Chem. Int. Edit. 2012, 51, 3119. P. Écija, I. Uriarte, L. Spada, B. G. Davis, W. Caminati, F. J. Basterretxea, A. Lesarri, E. J. Cocinero, Chem. Commun. 2016, 52, 6241. I. Peña, E. J. Cocinero, C. Cabezas, A. Lesarri, S. Mata, P. Écija, A. M. Daly, Á. Cimas, C. Bermúdez, F. J. Basterretxea, S. Blanco, J. A. Fernández, J. C. López, F. Castaño, J. L. Alonso, Angew. Chem. Int. Edit. 2013, 52, 11840.

  15. Gas Phase Transport, Adsorption and Surface Diffusion in Porous Glass Membrane

    Czech Academy of Sciences Publication Activity Database

    Yang, J.; Čermáková, Jiřina; Uchytil, Petr; Hamel, Ch.; Seidel-Morgenstern, A.

    2005-01-01

    Roč. 104, 2-4 (2005), s. 344-351 ISSN 0920-5861. [International Conference on Catalysis in Membrane Reactors /6./. Lahnstein, 06.07.2004-09.07.2004] R&D Projects: GA AV ČR(CZ) IAA4072402 Institutional research plan: CEZ:AV0Z40720504 Keywords : gas phase transport * vycor glass * adsorption Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.365, year: 2005

  16. Position for determining gas-phase volatile organic compound concentrations in transuranic waste containers. Revision 2

    Energy Technology Data Exchange (ETDEWEB)

    Connolly, M.J.; Liekhus, K.J. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Djordjevic, S.M.; Loehr, C.A.; Spangler, L.R. [Benchmark Environmental Corp. (United States)

    1998-06-01

    In the conditional no-migration determination (NMD) for the test phase of the Waste Isolation Pilot Plant (WIPP), the US Environmental Protection Agency (EPA) imposed certain conditions on the US Department of Energy (DOE) regarding gas phase volatile organic compound (VOC) concentrations in the void space of transuranic (TRU) waste containers. Specifically, the EPA required the DOE to ensure that each waste container has no layer of confinement that contains flammable mixtures of gases or mixtures of gases that could become flammable when mixed with air. The EPA also required that sampling of the headspace of waste containers outside inner layers of confinement be representative of the entire void space of the container. The EPA stated that all layers of confinement in a container would have to be sampled until DOE can demonstrate to the EPA that sampling of all layers is either unnecessary or can be safely reduced. A test program was conducted at the Idaho National Engineering and Environmental Laboratory (INEEL) to demonstrate that the gas phase VOC concentration in the void space of each layer of confinement in vented drums can be estimated from measured drum headspace using a theoretical transport model and that sampling of each layer of confinement is unnecessary. This report summarizes the studies performed in the INEEL test program and extends them for the purpose of developing a methodology for determining gas phase VOC concentrations in both vented and unvented TRU waste containers. The methodology specifies conditions under which waste drum headspace gases can be said to be representative of drum gases as a whole and describes a method for predicting drum concentrations in situations where the headspace concentration is not representative. The methodology addresses the approach for determining the drum VOC gas content for two purposes: operational period drum handling and operational period no-migration calculations.

  17. Position for determining gas phase volatile organic compound concentrations in transuranic waste containers. Revision 1

    International Nuclear Information System (INIS)

    Connolly, M.J.; Liekhus, K.J.; Djordjevic, S.M.; Loehr, C.A.; Spangler, L.R.

    1995-08-01

    In the conditional no-migration determination (NMD) for the test phase of the Waste Isolation Pilot Plant (WIPP), the US Environmental Protection Agency (EPA) imposed certain conditions on the US Department of Energy (DOE) regarding gas phase volatile organic compound (VOC) concentrations in the void space of transuranic (TRU) waste containers. Specifically, the EPA required the DOE to ensure that each waste container has no layer of confinement that contains flammable mixtures of gases or mixtures of gases that could become flammable when mixed with air. The EPA also required that sampling of the headspace of waste containers outside inner layers of confinement be representative of the entire void space of the container. The EPA stated that all layers of confinement in a container would have to be sampled until DOE can demonstrate to the EPA that sampling of all layers is either unnecessary or can be safely reduced. A test program was conducted at the Idaho National Engineering Laboratory (INEL) to demonstrate that the gas phase VOC concentration in the void space of each layer of confinement in vented drums can be estimated from measured drum headspace using a theoretical transport model and that sampling of each layer of confinement is unnecessary. This report summarizes the studies performed in the INEL test program and extends them for the purpose of developing a methodology for determining gas phase VOC concentrations in both vented and unvented TRU waste containers. The methodology specifies conditions under which waste drum headspace gases can be said to be representative of drum gases as a whole and describes a method for predicting drum concentrations in situations where the headspace concentration is not representative. The methodology addresses the approach for determining the drum VOC gas content for two purposes: operational period drum handling and operational period no-migration calculations

  18. Mechanisms of gas phase decomposition of C-nitro compounds from quantum chemical data

    International Nuclear Information System (INIS)

    Khrapkovskii, Grigorii M; Shamov, Alexander G; Nikolaeva, E V; Chachkov, D V

    2009-01-01

    Data on the mechanisms of gas-phase monomolecular decomposition of nitroalkanes, nitroalkenes and nitroarenes obtained using modern quantum chemical methods are described systematically. The attention is focused on the discussion of multistage decomposition of nitro compounds to elementary experimentally observed products. Characteristic features of competition of different mechanisms and the effect of molecular structure on the change in the Arrhenius parameters of the primary reaction step are considered.

  19. Origin of Asymmetric Charge Partitioning in the Dissociation of Gas-Phase Protein Homodimers

    OpenAIRE

    Jurchen, John C.; Williams, Evan R.

    2003-01-01

    The origin of asymmetric charge and mass partitioning observed for gas-phase dissociation of multiply charged macromolecular complexes has been hotly debated. These experiments hold the potential to provide detailed information about the interactions between the macromolecules within the complex. Here, this unusual phenomenon of asymmetric charge partitioning is investigated for several protein homodimers. Asymmetric charge partitioning in these ions depends on a number of factors, including ...

  20. Dynamics of gas-phase transient species studied by dissociative photodetachment of molecular anions

    OpenAIRE

    Lu, Zhou

    2007-01-01

    Gas-phase transient species, such as the CH₃CO₂ and HOCO free radicals, play important roles in combustion and environment chemistry. In this thesis work, the dynamics of these two radicals were studied by dissociative photodetachment (DPD) of the negative ions, CH₃CO₂-С and HOCO⁻, respectively. The experiments were carried out with a fast-ion-beam photoelectron-photofragment coincidence (PPC) spectrometer. Mass-selected molecular anions in a fast ion beam were intercepted by a linearly polar...