Готові списки джерел за темами / Quadrupolar phase

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Опубліковано: 6 вересня 2023

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Статті в журналах з теми "Quadrupolar phase"

Amm, David T., Stanley L. Segel, and Kenneth R. Jeffrey. "Hydroxide-ion dynamics in cesium hydroxide: a deuteron nuclear magnetic resonance study." Canadian Journal of Physics 64, no. 1 (January 1, 1986): 22–26. http://dx.doi.org/10.1139/p86-004.

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CSOD exists in a number of solid phases that are distinguished by the different equilibrium positions and dynamics of the OD− ion. Deuteron nuclear magnetic resonance (NMR) was used as a probe because the observed quadrupolar split spectra provide a sensitive means of detecting changes in the symmetry properties of the unit cell and the motion of the O—D bond. Measurements are reported for the nuclear quadrupole coupling constant and the effective asymmetry parameter over the range from 100 to 500 K. The NMR data as well as differential thermal analysis confirm phase transitions from the cubic (Pm3m) to the high-temperature orthorhombic phase (Cmcm) at 497 K and a transition to a lower temperature phase at 247 K. The quadrupolar split spectra in the region from 497 to 247 K are consistent with a twofold reorientation of the O—D bond throughout this phase. The effective asymmetry parameter of the quadrupolar interaction increases rapidly with decreasing temperature, indicating a substantial change in the angle of reorientation. Below 247 K the spectra suggest that the motion of the OD− ion slows down on the time scale of the NMR line width (10−5 s).

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O’Shea, Seamus F., Girija S. Dubey, and Jayendran C. Rasaiah. "Phase transitions of quadrupolar fluids." Journal of Chemical Physics 107, no. 1 (July 1997): 237–42. http://dx.doi.org/10.1063/1.474370.

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Makrinich, Maria, and Amir Goldbourt. "1H-Detected quadrupolar spin–lattice relaxation measurements under magic-angle spinning solid-state NMR." Chemical Communications 55, no. 39 (2019): 5643–46. http://dx.doi.org/10.1039/c9cc01176e.

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Kadowaki, H., H. Takatsu, T. Taniguchi, B. Fåk, and J. Ollivier. "Composite Spin and Quadrupole Wave in the Ordered Phase of Tb2+xTi2-xO7+y." SPIN 05, no. 02 (June 2015): 1540003. http://dx.doi.org/10.1142/s2010324715400032.

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The hidden ordered state of the frustrated pyrochlore oxide Tb 2+x Ti 2-x O 7+y is possibly one of the two electric multipolar, or quadrupolar, states of the effective pseudospin-1/2 Hamiltonian derived from crystal-field ground state doublets of non-Kramers Tb 3+ ions. These long-range orders are antiparallel or parallel alignments of transverse pseudospin components representing electric quadrupole moments, which cannot be observed as magnetic Bragg reflections by neutron scattering. However, pseudospin waves of these states are composite waves of the magnetic-dipole and electric-quadrupole moments, and can be partly observed by inelastic magnetic neutron scattering. We calculate these spin-quadrupole waves using linear spin-wave theory and discuss previously observed low-energy magnetic excitation spectra of a polycrystalline sample with x = 0.005(T c = 0.5 K).

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Lim, C. C. "Phase Transition to Quadrupolar Vortices in a Spherical Model of the Energy-Enstrophy Theory — Exact Solution." Nelineinaya Dinamika 16, no. 4 (2020): 543–55. http://dx.doi.org/10.20537/nd200402.

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A new energy-enstrophy model for the equilibrium statistical mechanics of barotropic flow on a sphere is introduced and solved exactly for phase transitions to quadrupolar vortices when the kinetic energy level is high. Unlike the Kraichnan theory, which is a Gaussian model, we substitute a microcanonical enstrophy constraint for the usual canonical one, a step which is based on sound physical principles. This yields a spherical model with zero total circulation, a microcanonical enstrophy constraint and a canonical constraint on energy, with angular momentum fixed to zero. A closed-form solution of this spherical model, obtained by the Kac – Berlin method of steepest descent, provides critical temperatures and amplitudes of the symmetry-breaking quadrupolar vortices. This model and its results differ from previous solvable models for related phenomena in the sense that they are not based on a mean-field assumption.

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Zhang, Weilu, Shangfei Wu, Shigeru Kasahara, Takasada Shibauchi, Yuji Matsuda, and Girsh Blumberg. "Quadrupolar charge dynamics in the nonmagnetic FeSe1−xSx superconductors." Proceedings of the National Academy of Sciences 118, no. 20 (May 12, 2021): e2020585118. http://dx.doi.org/10.1073/pnas.2020585118.

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We use polarization-resolved electronic Raman spectroscopy to study quadrupolar charge dynamics in a nonmagnetic FeSe1−xSx superconductor. We observe two types of long-wavelength XY symmetry excitations: 1) a low-energy quasi-elastic scattering peak (QEP) and 2) a broad electronic continuum with a maximum at 55 meV. Below the tetragonal-to-orthorhombic structural transition at TS(x), a pseudogap suppression with temperature dependence reminiscent of the nematic order parameter develops in the XY symmetry spectra of the electronic excitation continuum. The QEP exhibits critical enhancement upon cooling toward TS(x). The intensity of the QEP grows with increasing sulfur concentration x and maximizes near critical concentration xcr≈0.16, while the pseudogap size decreases with the suppression of TS(x). We interpret the development of the pseudogap in the quadrupole scattering channel as a manifestation of transition from the non-Fermi liquid regime, dominated by strong Pomeranchuk-like fluctuations giving rise to intense electronic continuum of excitations in the fourfold symmetric high-temperature phase, to the Fermi liquid regime in the broken-symmetry nematic phase where the quadrupole fluctuations are suppressed.

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Harris, A. Brooks, and Horst Meyer. "Orientational ordering in solid ortho–para H2 mixtures and analogy with a spin glass." Canadian Journal of Physics 63, no. 1 (January 1, 1985): 3–23. http://dx.doi.org/10.1139/p85-002.

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A review is presented of our understanding of the orientational ordering in solid hydrogen, where ortho-H2 molecules are subject to anisotropic electric quadrupole–quadrupole interactions. This review pertains to solid H2 at low pressures and is concerned mostly with NMR experiments. After a discussion of the phase transition from the disordered hexagonal close-packed (hep) to the long-range ordered cubic phase, a description is given of experimental investigations of the ordering in the hep phase for ortho concentrations X < 0.53. This ordering appears to take place continuously as the temperature decreases. The question as to whether or not this phase is to be called a quadrupolar glass phase is addressed, and comparison is made with the orientational freezing in other compounds. A theoretical analysis is given to show that the ortho–para mixture is the analog of a spin glass in a random field for which no phase transition is expected.

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Akazawa, Teruhiko, Takashi Suzuki, Hiroshi Goshima, Tomohiro Tahara, Toshizo Fujita, Toshiro Takabatake, and Hironobu Fujii. "Quadrupolar and Magnetic Phase Diagram of UNiSn." Journal of the Physical Society of Japan 67, no. 9 (September 15, 1998): 3256–60. http://dx.doi.org/10.1143/jpsj.67.3256.

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Scalise, O. H., R. D. Gianotti, G. J. Zarragoicoechea, and A. E. Rodríguez. "Phase equilibria in quadrupolar fluid binary mixtures." Journal of Chemical Physics 89, no. 2 (July 15, 1988): 1078–82. http://dx.doi.org/10.1063/1.455261.

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Vega, C., B. Garzón, S. Lago, and P. A. Monson. "Understanding the phase diagrams of quadrupolar molecules." Journal of Molecular Liquids 76, no. 3 (May 1998): 157–69. http://dx.doi.org/10.1016/s0167-7322(98)00060-9.

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Дисертації з теми "Quadrupolar phase"

Sales, Nilva Lúcia Lombardi. "Interação quadrupolar em compostos cúbicos à base de praseodímeo." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-24062008-085924/.

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Este trabalho segue os passos históricos, descritos na literatura, das interações normalmente consideradas nos sistemas intermetálicos de terras raras. O capítulo 2 considera o efeito do campo elétrico gerado pela distribuição de cargas no cristal, por isso denominado de campo elétrico cristalino. Já o capítulo 3 descreve o passo seguinte que é considerar uma interação entre dois íons vizinhos do cristal. Essa interação ocorre por mediação de elétrons itinerantes e é conhecida como interação de Ruderman-Kittel- Kasuya-Yosida, ou interação RKKY. Considerando-se apenas estas duas interações já é possível explicar boa parte do comportamento magnético dos compostos intermetálicos de terras raras. O PrMg2 é uma exceção para o qual a interação quadrupolar tem sido sugerida na literatura. A adição desta interação é o principal objetivo deste trabalho e tema do capítulo 4. A dependência dos parâmetros de ordem magnético e quadrupolar com a temperatura são estudados com a aproximação de campo médio. A estabilidade destes parâmetros é analisada através da energia livre na aproximação de campo médio (ao contrário da expansão de Landau, uma aproximação comum na literatura). Um diagrama de fases é obtido mostrando natureza do estado fundamental do Hamiltoniano de campo médio e o tipo de transição de fase (primeira ou segunda ordem) em função dos acoplamentos magnéticos e quadrupolares. É mostrado que o PrMg2 tem uma transição de fase de segunda ordem, como observado experimentalmente, após a inclusão de um acoplamento antiferroquadrupolar do tipo Heisenberg. Os cálculos numéricos foram feitos usando o programa Maple 5, e os códigos usados são mostrados nos apêndices A e C.
This work considers the presence of interactions in rare earth intermetallic compounds with cubic symmetry. In chapter 2 the crystalline electric field is taken into account and in chapter 3 an RKKY interaction between nearest neighbours is introduced in order to obtain magnetic order in the crystal. These interactions alone are sufficient to explain magnetic behavior of several based Pr compounds, with PrMg2 an exception for what a quadrupolar interaction has been proposed in the literature; the addition of this interaction constitutes the principal goal of this work and is developed in chapter 4. The temperature dependence of the magnetic- and quadrupolar-order parameters is studied under the mean-field approximation. The stability of those parameters are analyzed by means of an exact mean-field free energy (as opposed of a Landau expansion, an approximation common in the literature). A phase diagram is obtained relating the magnetic and quadrupolar couplings with the nature of the ground state mean-field Hamiltonian and the kind of the phase transitions (first or second). It is showed that the PrMg2 undergoes a second order phase transition, as observed experimentally, after an inclusion of a Heisenberg like antiferroquadrupolar coupling. The numerical calculations were performed using the Maple software and the codes are listed in the appendix.

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Bristow, Anthony Walter Thomas. "Laser desorption and high resolution studies in quadrupole ion trap mass spectrometry." Thesis, Nottingham Trent University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336973.

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Malik, A. Q. "Kinetic studies of gas phase cations by charge-exchange techniques in a two-quadrupole tandem mass spectrometer." Thesis, University of Essex, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372588.

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Powoski, Robert A. "Molecular Structure Analyses of Asymmetric Hydrocarbon Liquid Compounds in the Gas Phase Using Chirped-pulse Fourier Transform Microwave Spectroscopy: Acyl Chlorides and Perfluorinated Acyl Chlorides." Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc103374/.

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Examinations of the effects of (a.) alkyl carbon chain length and (b.) perfluorination of acyl chlorides; propionyl chloride, butyryl chloride, valeroyl chloride, and perfluorinated acyl chlorides; perfluoropropionyl chloride and perfluorobutyryl chloride, are reported and compared using CP-FTMW spectroscopy. All of these molecules are already published in various journals except for valeroyl chloride. The chapters are organized by molecule alkyl chain length and include some background theory. Conformational stability, internal rotation, helicity, and ionic character of the C-Cl bond via the nuclear electric quadrupole coupling constant (χzz) are analyzed. Results show syn, syn-anti/syn-gauche, and syn-anti-anti/syn-gauche-anti stable conformations. Internal rotation was only seen in propionyl chloride. Helicity was not observed. (χzz) was observed to be inert to alkyl chain length, ~ 60 MHz and ~ 65 MHz for the nonfluorinated and fluorinated acyl chlorides. Partial fluorination and varying functional groups are recommended.

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Hall, Robin Gibson. "The development of a quinquaquadrupole mass spectrometer : the study of ion-molecule reactions in the gas phase using multiple quadrupole instruments." Thesis, University of St Andrews, 1991. http://hdl.handle.net/10023/15506.

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The field of quadrupole mass spectrometry has grown enormously since the early 1980's. The invention of the triple quadrupole mass spectrometer led to the development of tandem quadrupole mass spectrometers of many different configurations. A large number of tandem quadrupole mass spectrometers have also been developed by linking one or more quadrupole mass filters to a traditional magnetic or electric filter. The versatility of multiple quadrupole mass spectrometers along with their potential to rapidly produce a huge amount of data on a particular ion makes them ideal instruments for routine analytical analysis as well as for fundamental research The quinquaquadrupole mass spectrometer has been developed as an extension to the available multiple quadrupole systems. It offers the possibility to obtain even more data on the fragmentation of ions as well as enabling the study of novel ions to be carried out. The development of the quinquaquadrupole mass spectrometer forms the main part of this thesis. Also discussed are the reactions studied to evaluate the instrumental performance. The the ion molecule reactions of some halogen containing cations with saturated and unsaturated hydrocarbons performed on the triple quadrupole mass spectrometer are also discussed.

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Hall, Bradley John. "Development of solid phase microextraction (SPME) and matrix assisted laser desorption ionization (MALDI) with quadrupole ion trap mass spectrometry for analytical applications /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

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Perumal, Karthick. "Epitaxial growth of Ge-Sb-Te based phase change materials." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16815.

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Ge-Sb-Te basierte Phasenwechselmaterialen sind vielersprechende Kandidaten für die Anwendung in optischen und elektrischen nicht-flüchtigen Speicheranwendungen. Diese Materialien können mit Hilfe von elektrischen oder optischen Pulsen reversibel zwischen der kristallinen und amorphen Struktur geschaltet werden. Diese stukturellen Phasen zeigen einen großen Unterschied in ihren elektronischen Eigenschaften, der sich in einer starken Änderung der optischen Reflektivität und des elektrischen Widerstands zeigt.Diese Studie befasst sich mit epitaktischem Wachstum und Analyse der epitaktischen Schichten. Der erste Teil der Arbiet befasst sich mir dem epitaktischen Wachstum von GeTe. Dünne GeTe Schichten wurden auf Si(111) und Si(001) Substraten mit einer Gitterfehlanpassung von 10.8% präpariert. Auf beiden Substraten bildet sich in der GeTe Schicht die [111] Oberflächenfacette parallel zur Si(001) und Si(111) Oberfläche aus. Während des inertialen Wachstums findet eine Phasentransformation von amorph zu kristallin statt. Diese Phasentransformation wurde mittels azimuthaler in-situ Beugung hochenergetischer Elektronen sowie in-situ Röntgenbeugung unter streifendem Einfall untersucht. Der zweite Teil der Arbeit wird die Epitaxie sowie die strukturelle Charakterisierung dünner Sb2Te3 Schichten dargestellt. Der dritte Teil umfasst die Epitaxie terniärer Ge-Sb-Te Schichten . Zum Wachstum wurden sowohl die Substrattemperatur als auch die Ge, Sb und Te Flüsse variiert. Es wird gezeigt, dass die Komposition der Schicht stark von der Wachtumstemperatur abhängt und nur entlang der pseudibinären Verbindungslinie von GeTe-Sb2Te3 variiert. Zur Kontrolle des Wachstums wurde dabei die in-situ Quadrupol Massenspektroskopie verwendet. Es zeigen sich diverse inkommensurate Beugungsmaxima entlang der [111] Oberflächennormalen der Schichten, anhand derer die Ausbildung einer Lehrstellen Ordnung in Form einer Überstruktur diskutiert wird.
Ge-Sb-Te based phase change materials are considered as a prime candidate for optical and electrical data storage applications. With the application of an optical or electrical pulse, they can be reversibly switched between amorphous and crystalline state, thereby exhibiting large optical and electrical contrast between the two phases, which are then stored as information in the form of binary digits. Single crystalline growth is interesting from both the academic and industrial perspective, as ordered Ge-Sb-Te based metamaterials are known to exhibit switching at reduced energies. The present study deals with the epitaxial growth and analysis of Ge-Sb-Te based thin films. The first part of the thesis deals with the epitaxial growth of GeTe. Thin films of GeTe were grown on highly mismatched Si(111) and (001) substrates. On both the substrate orientations the film grows along [111] direction with an amorphous-to-crystalline transition observed during the initial stages of growth. The amorphous-to-crystalline transition was studied in-vivo using azimuthal reflection high-energy electron diffraction scans and grazing incidence x-ray diffraction. In the second part of the thesis epitaxy and characterization of Sb2Te3 thin films are presented. The third part of the thesis deals with the epitaxy of ternary Ge-Sb-Te alloys. The composition of the films are shown to be highly dependent on growth temperatures and vary along the pseudobinary line from Sb2Te3 to GeTe with increase in growth temperatures. A line-of-sight quadrupole mass spectrometer was used to reliably control the GeSbTe growth temperature. Growth was performed at different Ge, Sb, Te fluxes to study the compositional variation of the films. Incommensurate peaks are observed along the [111] direction by x-ray diffraction. The possibility of superstructural vacancy ordering along the [111] direction is discussed.

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Robb, Damon Bradley. "Studies of the effects of the amplitude and phase of the RF potential on the trapping process in laser desorption quadrupole ion trap mass spectrometry." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ34617.pdf.

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Christides, Achille. "Spectrométrie pulsée de R. Q. N. Et contribution à l'étude de la phase incommensurable de β-ThBr ₄". Paris 11, 1987. http://www.theses.fr/1987PA112068.

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On décrit la réalisation d'un spectromètre pulsé informatisé effectuée à partir d'un montage antérieur dont les performances ont été améliorées. Cette réalisation se situe dans la perspective de l'extension des possibilités de recherche du service de R. Q. N. Et s'intègre dans un ensemble informatisé assurant le traitement des données expérimentales et une automatisation des mesures. Le spectromètre réalisé est entièrement transistorisé et couvre une gamme de fréquences s'étendant de quelques centaines de kilohertz à 60 MHz. Les circuits sont à large bande à l'exception d'un circuit accordable réducteur de bande passante destiné à éviter la saturation du récepteur par le bruit aux gains élevés et du Circuit Oscillant principal. Il en résulte à ce niveau une réduction du nombre des réglages nécessaires et une simplification dans l'utilisation de l'ensemble. Les progrès réalisés concernent le taux de réjection de la porte analogique (> 60 db jusqu'à 80 MHz)- l'augmentation de la fréquence maximale de fonctionnement (80 MHz pour la porte et le récepteur, 60 MHz pour l'émetteur)- la puissance d'émission (100 W) et le temps de récupération du récepteur (15 µs en l'absence du Circuit Oscillant contenant l'échantillon. Ce spectromètre a été utilisé pour l'étude de la phase incommensurable de ThB4. Les études antérieures sur ce produit avaient été effectuées avec un spectromètre à superréaction dont les limitations pour l'étude de la forme des raies sont connues. Avec le spectromètre pulsé la nature de la raie de résonance large fournie par l'échantillon dans la phase incommensurable a été confirmée; dans la gamme de température étudiée dans ce travail (77-95K), la raie reste sensiblement symétrique (indiquant une modulation sinusoïdale simple de la structure cristalline). L'étude de T1 montre la forte relaxation nucléaire au voisinage de la transition de phase en relation avec les fluctuations associées à la condensation du "mode mou" responsable de la transition
We describe the realization of the radio-frequency sections of a pulsed and computerized N. Q. R. Spectrometer, the design of which is derived from a system existing at the Laboratory. The performances were improved and the design made with a view to increase the versatility of the N. Q. R. Research Group facilities. The all solid-state spectrometer can be operated from a few hundred hertz up to 60 MHz. Circuits are wide-band except for the tank circuit and a tunable pass-band circuit provided to reduce the amplified noise level; as a result adjustments when operating the system are minimized and phase shift problems are eliminated. The rejection ratio of the analogic gate is increased and still 60 db at 80 MHz. The transmitting power stage, also transistorized, can deliver one hundred watts up to 60 MHz time 15 µs. The receiver pass-band is 80 MHz and its recovery when the high-Q tank circuit is not connected. The spectrometer has been used for investigating the incommensurate phase of ß-ThBr4 below 96 K. As compared with previous measurements made with a SRO spectrometer of poor re solution as line shape studies are considered, this series of investigations brings new pieces of information about the actual shape of the broad bromine N. Q. R. Line observed in the incommensurate phase below 96 K. In the range of temperature investigated so far (77-96 K), the line remains quite symmetrical with respect to its center frequency suggesting that the modulation is of the sine plane wave type. Investigation of the relaxation time, T1, shows a strong relaxation near the phase transition temperature quite probably related to the soft mode condensation at the transition temperature

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Bonnisseau, Dominique. "Etude des structures magnétiques de composés de neptunium (NpAs, NpSb, NpSe et NpRu2Si2)." Grenoble 1, 1987. http://www.theses.fr/1987GRE10144.

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Книги з теми "Quadrupolar phase"

Wells, Nikita. Radio frequency quadrupole and alternating phase focusing methods used in proton linear accelerator technology in the USSR. Santa Monica, CA: Rand, 1985.

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Частини книг з теми "Quadrupolar phase"

Ordonez, Andres F., and Olga Smirnova. "Inducing Enantiosensitive Permanent Multipoles in Isotropic Samples with Two-Color Fields." In Molecular Beams in Physics and Chemistry, 335–52. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63963-1_16.

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AbstractWe find that two-color fields can induce field-free permanent dipoles in initially isotropic samples of chiral molecules via resonant electronic excitation in a one-$$3\omega $$ 3 ω -photon versus three-$$\omega $$ ω -photons scheme. These permanent dipoles are enantiosensitive and can be controlled via the relative phase between the two colors. When the two colors are linearly polarized perpendicular to each other, the interference between the two pathways induces excitation sensitive to the molecular handedness and orientation, leading to uniaxial orientation of the excited molecules and to an enantio-sensitive permanent dipole perpendicular to the polarization plane. We also find that although a corresponding one-$$2\omega $$ 2 ω -photon versus two-$$\omega $$ ω -photons scheme cannot produce enantiosensitive permanent dipoles, it can produce enantiosensitive permanent quadrupoles that are also controllable through the two-color relative phase.

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Chen, Guan-yuan, and Qibin Zhang. "Quantification of Plasma Oxylipins Using Solid-Phase Extraction and Reversed-Phase Liquid Chromatography-Triple Quadrupole Mass Spectrometry." In Methods in Molecular Biology, 171–86. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-1410-5_12.

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Kempen, E. C., A. Colorado, and J. S. Brodbelt. "Gas-Phase Dissociation Energies of Hydrogen-Bonded Complexes in a Quadrupole Ion Trap Mass Spectrometer." In New Methods for the Study of Biomolecular Complexes, 141–47. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-015-9046-4_11.

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Yoshimura, K., T. Uemura, M. Kato, T. Shibata, K. Kosuge, T. Imai, and H. Yasuoka. "Magnetic Phase Differentiation in the La2-xSrxCuOy System — Cu and La Nuclear Quadrupole Resonance and Relaxation." In Springer Proceedings in Physics, 405–7. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-77154-5_80.

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Anderson, Sharon J. "Proton and 19F NMR Spectroscopy of Pesticide Intermolecular Interactions." In Nuclear Magnetic Resonance Spectroscopy in Environment Chemistry. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195097511.003.0008.

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Sorption of organic pollutants by soils and sediments is one of the main chemical processes that controls pollutant migration in the environment. Information about the molecular mechanisms by which an organic pollutant interacts with other solution-phase constituents and with solid-phase sorbents would be invaluable for more accurate prediction of pollutant fate and transport and for optimal design and application of remediation procedures. Many current models and remediation strategies are based upon the “partition theory” of organic compound sorption, which predicts sorption coefficients from properties such as water solubility or octanol-water partition coefficients. Partition theory is well suited for nonpolar hydrocarbons but may not be appropriate for pesticides with electrophilic or weakly acidic or basic substituents, which may interact with soils or organic matter through specific interactions such as hydrogen bonding or charge-transfer complexes. If a pesticide can form hydrogen bonds or a charge-transfer complex with a sorbent, sorption may be greater than in the absence of specific interactions. Nuclear magnetic resonance (NMR) spectroscopy is well suited for the study of pesticide-solution or pesticide-sorbent interactions because NMR is an element-specific method that is extremely sensitive to the electron density (shielding) near the nucleus of interest. Consequently, solution-state NMR can distinguish between closely related functional groups and can provide information about intermolecular interactions. All nuclei with nonzero nuclear spin quantum number can be studied by NMR spectroscopy. Of the more than 100 NMR-active nuclei, 1H and 19F are the easiest to study because both have natural abundances near 100% and greater NMR sensitivity than any other nuclei. In addition, both 1H and 19F have zero quadrupolar moments, which means that sharp, well resolved NMR peaks can be obtained, at least in homogeneous solutions. Proton NMR is well suited for elucidating molecular interactions in solution but cannot be used to study interactions between pesticides and heterogeneous sorbents such as soils, humic acid, or even cell extracts, since protons in the sorbent generally produce broad peaks that mask the NMR peaks from the solute or sorbate of interest. In contrast, 19F NMR can be used to study interactions between fluorine-containing molecules and heterogeneous sorbents because the fluorine concentration in most natural sorbents is negligible.

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Chipuk, Joseph, and Jennifer Brodbelt. "Gas-Phase Hydrogen/Deuterium Exchange in Quadrupole-Ion Traps." In Practical Aspects of Trapped Ion Mass Spectrometry, Volume V, 35–57. CRC Press, 2009. http://dx.doi.org/10.1201/9781420083743-c2.

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"Chapter Gas-Phase Hydrogen/Deuterium Exchange in Quadrupole- Ion Traps." In Practical Aspects of Trapped Ion Mass Spectrometry, Volume V, 67–90. CRC Press, 2016. http://dx.doi.org/10.1201/9781420083743-8.

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Lesot, Philippe, and Olivier Lafon. "Combining Fast 2D NMR Methods and Oriented Media." In Fast 2D Solution-state NMR, 441–75. The Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/bk9781839168062-00441.

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NMR in oriented samples (anisotropic solvents) offers access to informative residual order-dependent NMR interactions, including chemical shift anisotropies (RCSAs), dipolar couplings (RDCs), and quadrupolar couplings (RQCs), while preserving high spectral resolution. The analysis of these spectra often requires two-dimensional (2D) NMR experiments due to these additional anisotropic interactions. In addition, accelerated 2D NMR experiments can be essential for particular investigations, including in situ monitoring of chemical reactions or the observation of dilute isotopes, e.g. 2H and 13C, since the stability of oriented phases is limited in time and the magnetic field, B0, can drift in the absence of 2H lock. We provide here an overview of these fast 2D NMR experiments in anisotropic media. These developments have benefited from those for isotropic solutions, such as fast pulsing techniques enhancing the polarization, sparse sampling, Hadamard spectroscopy or spatial encoding. Nevertheless, fast 2D NMR in mesophases and solids present particular challenges, since these 2D spectra usually display lower signal-to-noise ratios, non-Lorentzian lineshapes, lower spectral resolution and wider spectral widths than their counterparts for isotropic solutions. We discuss here the advantages and limitations of various approaches, which have been applied for the fast 2D NMR spectra of mesophases and solids.

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Randall, H. T., P. L. Mills, and J. S. McCracke. "A novel laboratory reactor for gas-phase transient kinetics based on time-of-flight and quadrupole mass spectroscopy." In Studies in Surface Science and Catalysis, 209–18. Elsevier, 1999. http://dx.doi.org/10.1016/s0167-2991(99)80150-5.

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McCullough, Bryan, Peter Faull, and Perdita Barran. "Development of an Ion-Mobility-Capable Quadrupole Time-of-Flight Mass Spectrometer to Examine Protein Conformation in the Gas Phase." In Ion Mobility Spectrometry - Mass Spectrometry, 75–104. CRC Press, 2010. http://dx.doi.org/10.1201/b10460-7.

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Тези доповідей конференцій з теми "Quadrupolar phase"

Singh, R. C., A. H. Siddiqi, M. Brokate, and A. K. Gupta. "AN INTEGRAL EQUATION APPROACH TO ORIENTATIONAL PHASE TRANSITIONS IN QUADRUPOLAR GAY-BERNE FLUID USING DENSITY-FUNCTIONAL THEORY." In MODELLING OF ENGINEERING AND TECHNOLOGICAL PROBLEMS: International Conference on Modelling and Engineering and Technological Problems (ICMETP) and the 9th Biennial National Conference of Indian Society of Industrial and Applied Mathematics (ISIAM). AIP, 2009. http://dx.doi.org/10.1063/1.3183552.

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Dake, Timothy J., and Joseph Majdalani. "Improving Flow Circulation in Heat Sinks Using Quadrupole Vortices." In ASME 2009 InterPACK Conference collocated with the ASME 2009 Summer Heat Transfer Conference and the ASME 2009 3rd International Conference on Energy Sustainability. ASMEDC, 2009. http://dx.doi.org/10.1115/interpack2009-89211.

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In this paper, we show that improved air circulation above a heat sink is possible using thin winglet-type vortex generators that can be passively retrofitted to an existing unit. By mounting these vortex generators on the leading edge of heat sink fins, pairs of counter-rotating vortices are induced within the interfin spacing. The vortices disturb the boundary layers and serve to mix the air in the interfin channel. The devices we have designed are passive and can be added to existing systems using a simple clip-on mechanism. In this study, several designs are experimentally investigated for the purpose of identifying the optimal configuration that will be most conducive to flow enhancement and, therefore, heat transfer augmentation. Using the typical operational range of air velocities for PCs, routers and servers, an experimental simulation of the interfin channel reveals that certain vortex generators, when placed upstream, can outperform others in their ability to fill the channel with pairs of strong vortices. Multiple pairs can also be generated to further accentuate the heat transfer using dual vortex generators. A description of the specific shapes is furnished here along with particulars of the performance study. By control and manipulation of the vortices, our results suggest the possibility of optimizing the generator design. Experimentation was conducted in two phases. The first phase is a study of the ability to generate and control vortices within the fin channel. This aspect was simulated using a Lexan mock-up of the fin channel that permits introduction of glycerin smoke to visualize the shape, size, strength and structure of the vortices. The clear Lexan permitted viewing of the vortices by passing a red planar laser through the apparatus. The second phase involved using the optimization data gained in the first phase to generate vortices in an actual heat sink fitted with thermocouples to measure the temperatures at various points during heating.

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Chyba, David E., and Peter F. Meier. "Periodic and chaotic solutions in a spin-1 model of the free-running ruby nuclear magnetic resonance laser." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oam.1987.md4.

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Previous studies of the ruby nuclear magnetic resonance laser1 have relied on a model of the system in which the 27AI nucleus is treated as a spin-½ (two-level) system. The semiclassical model which results is reducible to two equations and so requires signal injection or modulation of a parameter to give chaotic behavior. A model involving a higher spin and more lasing levels may require a higher dimensional phase space and may, therefore, give chaotic behavior even in the free-running case. Our model is derived from a Hamiltonian for a spin-1 object in superimposed static and sinusoidally oscillating magnetic fields, incorporating also the simplest possible quadrupole interaction. The quadrupole splitting can be experimentally adjusted and is considered as a control parameter along with the excitation. With additional simplifications, a set of four equations of motion can be obtained. These reduce to the earlier two-equation model in the limit of zero quadrupole splitting. We have found period-doubling bifurcations of certain limit cycles leading to chaotic solutions. Further work is in progress, including removing some of the restrictions involved in the reduction to the four-equation system.

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Yi Yuanrui, Zhao Xia, Wang Cong, Yan Wei, Gao Qiang, and Wang Qianggang. "Dynamic model for quadrupole six-phase electrical excitation synchronous wind power system." In 9th IET International Conference on Advances in Power System Control, Operation and Management (APSCOM 2012). Institution of Engineering and Technology, 2012. http://dx.doi.org/10.1049/cp.2012.2155.

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Jin, Jicheng, Li He, Jian Lu, Eugene J. Mele, and Bo Zhen. "Floquet topological quadrupole in photonic crystals protected by space-time symmetry." In CLEO: QELS_Fundamental Science. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/cleo_qels.2022.ftu5j.3.

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We present that a space-time screw symmetry can be preserved in periodically driven optical nonlinear materials. Such symmetry can protect a high-order topological phase, which is demonstrated with a photonic crystal.

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Sako, Hiroyuki. "Current Status and Performance of the J-PARC Accelerators." In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75557.

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J-PARC (Japan Proton Accelerator Research Complex) is a multi-purpose research facility for materials and life sciences, nuclear and particle physics, and nuclear engineering with extremely high power proton beams of 1 MW. The accelerator complex consists of a 400-MeV linac, a 3-GeV Rapid Cycling Synchrotron (RCS), and a 50-GeV Main Ring synchrotron (MR). Its goals are to provide MW-class beams at 3 GeV and at several 10 GeV, while it is a challenge to localize and suppress beam loss to the level to allow hands-on maintenance of accelerator components. The RCS scheme is adopted to realize them, which is advantageous over conventional Accumulation Ring (AR) regarding less beam loss problems due to lower beam current and easier construction and operation of a linac. RCS, however, required various challenging technologies such as ceramic ducts to reduce eddy current effects, high field Radio Frequency (RF) system, and paint injection technique (an injection scheme to reduce phase space density of the beam) to reduce space charge effects. The linac has also unique technologies to minimize beam loss, such as compact electromagnet Drift Tube Quadrupoles (DTQ’s) to control beam envelopes precisely, and a fast beam suspending system in Machine Protection System (MPS) with Radio Frequency Quadrupole linac (RFQ). The beam commissioning of the linac started in Nov. 2006, and its design energy of 181 MeV in the first construction phase was achieved in Jan. 2007. RCS beam commissioning started in Sep. 2007 and the beam was accelerated to the designed energy of 3 GeV in Oct. 2007. MR beam commissioning started in May 2008, and the beam acceleration to 30 GeV was established in Dec. 2008. The first neutron and muon beams were produced in May and Sep. 2008, respectively, at Materials and Life science experimental Facility (MLF). The linac commissioning has resulted in very stable beam with short down time. RCS commissioning quickly achieved beam acceleration and extraction, and paint injections are being studied intensively. RCS recorded the highest beam power of 0.21 MW in Sep. 2008 with beam loss well localized at the collimators. The linac beam energy will be upgraded to 400 MeV with Annular Coupled Structure linac (ACS) in order to increase the beam power to 1 MW. In the second construction phase, upgrade of the linac with 600-MeV Super-Conducting Linac (SCL) for Accelerator-Driven nuclear waste transmutation System (ADS) and upgrade of MR energy from 30 to 50 GeV are planned.

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Hemberger, P. H., N. S. Nogar, and J. Williams. "Laser Photodissociation Probe for Ion Tomography Studies in a Quadrupole Ion Trap Mass Spectrometer." In Laser Applications to Chemical Analysis. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/laca.1992.wb2.

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Operation of a quadrupole ion trap mass spectrometer depends intimately on the details of ion trajectories in the trapping field 1,2. Stable ion trajectories provide storage of ions for reactive3 and spectroscopic studies4-6 while unstable trajectories allow selective ejection of ions for mass analysis7. Clearly, the details of ion trajectories, including spatial and velocity distributions, and the effects of drive frequency, phase and amplitude, and gas pressure, are crucial to the performance of an ion trap mass spectrometer.

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Wang, Xiangdong, Ziteng Wang, Zhichan Hu, Domenico Bongiovanni, Daohong Song, Roberto Morandotti, Hrvoje Buljan, and Zhigang Chen. "Topological corner states mediated by quadrupole polarization and Dirac-like band touching." In CLEO: QELS_Fundamental Science. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/cleo_qels.2022.ftu1b.6.

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We demonstrate corner states in trivial and nontrivial 2D SSH lattices diagonally stretched to exhibit both HOTI and higher-order semimetal-like features and examine the underlying topological mechanisms from the calculated spectral phase density.

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Ihara, Yoshihiko, Hideo Takeya, Kenji Ishida, Chishiro Michioka, Kazuyoshi Yoshimura, Kazunori Takada, Takayoshi Sasaki, Hiroya Sakurai, and Eiji Takayama-Muromachi. "Co Nuclear-Quadrupole-Resonance Measurements on NaxCoO2⋅yH2O — Phase Diagram for Bilayered-Hydrate System." In LOW TEMPERATURE PHYSICS: 24th International Conference on Low Temperature Physics - LT24. AIP, 2006. http://dx.doi.org/10.1063/1.2354884.

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Коненков, Н. В., А. И. Иванов та В. А. Степанов. "ГАУССОВ ПУЧОК КАК МОДЕЛЬ ИСТОЧНИКА ИОНОВ". У Актуальные проблемы физики и технологии в образовании, науке и производстве. Crossref, 2021. http://dx.doi.org/10.37724/z6586-3254-5949-f.

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Для расчета статистического аксептанса КФМ использовался траекторный метод. Функция плотности вероятности захваченных фазовых точек предназначена для определения матриц вторых моментов. Элементы этих матриц описывают эллипсы захвата на X и Y фазовых плоскостях. Мерой согласования Гауссова пучка и аксептанса квадруполя служат площади эллипсов. При постоянных параметрах Гауссова пучка ионов эффективность согласования слабо уменьшается с увеличением разрешающей способности. Полученные данные будут полезны при проектировании современных источников ионов. To calculate the statistical QMF acceptance, an ion trajectory method has been used. The probability density functions of accepted points allow fitting the matrix of the second moments. The elements of these matrices describe the acceptance ellipses on phase X and Y planes. The measure of the coupling Gaussian beam and quadrupole acceptance is ellipse area. Colored distributions of the input and output coordinates and velocities are presented, in which the initial phases are marked with different colors. It was found that with increasing resolution, the statistical acceptance ellipses are nested into each other. At constant parameters of the input Gaussian beam, the matching efficiency weakly decreases with resolution. The obtained data will be useful for creation a new modern ion sources.

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Звіти організацій з теми "Quadrupolar phase"

Mulcahy, H., and C. Koester. Experiments with the LECO Pegasus Gas Chromatograph/ Time-of-Flight Mass Spectrometer Phase 1: Fast GC Separations and Comparison of the GC/TOF-MS with Conventional Quadrupole GC/MS and Fast Quadrupole GC/MS. Office of Scientific and Technical Information (OSTI), August 2012. http://dx.doi.org/10.2172/1056608.

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