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Sample records for low-lying quadrupole vibrations

  1. Robust correlations between quadrupole moments of low-lying 2+ states within random-interaction ensembles

    NASA Astrophysics Data System (ADS)

    Lei, Y.

    2016-02-01

    In random-interaction ensembles, three proportional correlations between quadrupole moments of the first two Iπ=2+ states robustly emerge, including Q (21+) =±Q (22+) correlations previously remarked by a realistic nuclear survey, and the Q (22+) =-3/7 Q (21+) correlation, which is only observed in the s d -boson space. These correlations can be microscopically characterized by the rotational SU(3) symmetry and quadrupole vibrational U(5) limit, respectively, according to the Elliott model and the s d -boson mean-field theory. The anharmonic vibration may be another phenomenological interpretation for the Q (21+) =-Q (22+) correlation, whose spectral evidence, however, is insufficient.

  2. Low-lying bands with different quadrupole deformation in 155Dy

    NASA Astrophysics Data System (ADS)

    Petkov, P.; Yavahchova, M. S.; Möller, O.; Dewald, A.; Saha, B.; Fitzler, A.; Jessen, K.; Tonev, D.; Klug, T.; Heinze, S.; Jolie, J.; von Brentano, P.; Goutev, N.; Bazzacco, D.; Ur, C. A.; Farnea, C. A.; Axiotis, M.; Lunardi, S.; de Angelis, G.; Napoli, D. R.; Marginean, N.; Martinez, T.; Caprio, M. A.

    2014-03-01

    To investigate the interplay between collective and single particle degrees of freedom in odd nuclei, Recoil distance Doppler-shift and Doppler-shift attenuation lifetime measurements were carried out for levels in 155Dy in coincidence detection of gamma-rays. 26 lifetimes were determined using the Differential decay curve method. Particle plus triaxial rotor model (PTRM) calculations were performed to compare the experimental level scheme and transition strengths with theoretical ones in order to get information on the quadrupole deformation (є,γ) of the bands. As a result, different quadrupole deformations for the one-quasineutron bands at low and medium spins are deduced.

  3. Transition from vibrational to rotational character in low-lying states of hypernuclei

    NASA Astrophysics Data System (ADS)

    Mei, H.; Hagino, K.; Yao, J. M.; Motoba, T.

    2017-07-01

    In order to clarify the nature of hypernuclear low-lying states, we carry out a comprehensive study of the structure of Λ 145-155Sm hypernuclei, which exhibit a transition from vibrational to rotational character as the neutron number increases. To this end, we employ a microscopic particle-core coupling scheme based on a covariant density functional theory. We find that the positive-parity ground-state band in the hypernuclei shares a similar structure to that of the corresponding core nucleus. That is, regardless of whether the core nucleus is spherical or deformed, each hypernuclear state is dominated by the single configuration of the Λ particle in the s1 /2 state (Λ s1 /2 ) coupled to one core state of the ground band. In contrast, the low-lying negative-parity states mainly consist of Λ p1 /2 and Λ p3 /2 configurations coupled to plural nuclear core states. We show that, while the mixing amplitude between these configurations is negligibly small in spherical and weakly deformed nuclei, it strongly increases as the core nucleus undergoes a transition to a well deformed shape, which is consistent with the Nilsson wave functions. We demonstrate that the structure of these negative-parity states with spin I can be well understood based on a naive L S coupling scheme, with total orbital angular momentum L =[I ⊗1 ] and spin angular momentum S =1 /2 .

  4. Origin of low-energy quadrupole collectivity in vibrational nuclei.

    PubMed

    Walz, C; Fujita, H; Krugmann, A; von Neumann-Cosel, P; Pietralla, N; Ponomarev, V Yu; Scheikh-Obeid, A; Wambach, J

    2011-02-11

    The coupling of the giant quadrupole resonance to valence-space configurations is shown to be the origin of the formation of low-lying quadrupole-collective structures in vibrational nuclei with symmetric and mixed-symmetric character with respect to the proton-neutron degree of freedom. For the first time experimental evidence for this picture is obtained from electron- and proton scattering experiments on the nucleus ^{92}Zr that are sensitive to the relative phase of valence-space amplitudes by quantum interference.

  5. gamma-ray spectroscopic study of calcium-48,49 and scandium-50 focusing on low lying octupole vibration excitations

    NASA Astrophysics Data System (ADS)

    McPherson, David M.

    An inverse kinematic proton scattering experiment was performed at the National Superconducting Cyclotron Laboratory (NSCL) using the GRETINA-S800 detector system in conjunction with the Ursinus College liquid hydrogen target. gamma-ray yields from the experiment were determined using geant4 simulations, generating state population cross sections. These cross sections were used to extract the delta_3 deformation length for the low-lying octupole vibration excitations in Ca-48,49 using the coupled channels analysis code fresco. Particle-core coupling in Ca-49 was studied in comparison to Ca-48 through determination of the neutron and proton deformation lengths. The total inverse kinematic proton scattering deformation lengths were evaluated for the low-lying octupole vibration excitations in Ca-48,49 to be delta_3(Ca-48, 3. -_1) = 1.0(2)fm,delta_3(Ca-49, 9/2. +_1) = 1.2(1)fm, delta_3 (Ca-49, 9/2. +_1) = 1.5(2)fm, delta_3(Ca-49,5/2. +_1) = 1.1(1)fm. Proton and neutron deformation lengths for two of theseoctupole states were also determined to be delta_p(Ca-48, 3. -_1) = 0.9(1)fm,delta_p (Ca-49, 9/2. +_1) = 1.0(1)fm, delta_n(Ca-48, 3. -_1) = 1.1(3)fm, anddelta_n(Ca-49, 9/2. +_1) = 1.3(3)fm. Additionally, the ratios of the neutronto proton transition matrix elements were also determined for these two states to be M_n/M_p(Ca-48, 3. -_1) = 1.7(6) and M_n/M_p(Ca-49, 9/2. +_1) = 2.0(5).Statistically, the derived values for these two nuclei are nearly identical.

  6. A Vibrating Wire System For Quadrupole Fiducialization

    SciTech Connect

    Wolf, Zachary

    2010-12-13

    A vibrating wire system is being developed to fiducialize the quadrupoles between undulator segments in the LCLS. This note provides a detailed analysis of the system. The LCLS will have quadrupoles between the undulator segments to keep the electron beam focused. If the quadrupoles are not centered on the beam axis, the beam will receive transverse kicks, causing it to deviate from the undulator axis. Beam based alignment will be used to move the quadrupoles onto a straight line, but an initial, conventional alignment must place the quadrupole centers on a straight line to 100 {micro}m. In the fiducialization step of the initial alignment, the position of the center of the quadrupole is measured relative to tooling balls on the outside of the quadrupole. The alignment crews then use the tooling balls to place the magnet in the tunnel. The required error on the location of the quadrupole center relative to the tooling balls must be less than 25 {micro}m. In this note, we analyze a system under construction for the quadrupole fiducialization. The system uses the vibrating wire technique to position a wire onto the quadrupole magnetic axis. The wire position is then related to tooling balls using wire position detectors. The tooling balls on the wire position detectors are finally related to tooling balls on the quadrupole to perform the fiducialization. The total 25 {micro}m fiducialization error must be divided between these three steps. The wire must be positioned onto the quadrupole magnetic axis to within 10 {micro}m, the wire position must be measured relative to tooling balls on the wire position detectors to within 15 {micro}m, and tooling balls on the wire position detectors must be related to tooling balls on the quadrupole to within 10 {micro}m. The techniques used in these three steps will be discussed. The note begins by discussing various quadrupole fiducialization techniques used in the past and discusses why the vibrating wire technique is our method

  7. Excitation of the low lying vibrational levels of H2O by O(3P) as measured on Spacelab 2

    NASA Technical Reports Server (NTRS)

    Meyerott, R. E.; Swenson, G. R.; Schweitzer, E. L.; Koch, D. G.

    1994-01-01

    The data from the infrared telescope (IRT), which was flown on space shuttle Challenger Spacelab 2 mission (July 1985), were originally reported by Koch et al. (1987) as originating from near orbital emissions, primarily H2O. In this study, analysis of this data was extended to determine the collisional cross sections for the excitation of the low lying vibrational levels of H2O, present in the orbiter cloud, by atmospheric O(3P). The evaluation of the contribution to the measured signal from solar excitation and ram O excitation of outgassing H2O permits the determination of the H2O column density and the excitation cross section of the (101) level at an O(3P) velocity of approximately 7.75 km/s. Contributions to the radiation in the 1.7-3.0 micron band by transitions from the (100), (001), and multiquantum excited levels are discussed. The findings of the study are (1) the IRT data for the 4.5-9.5 micron and the nighttime data for the 1.7-3.0 micron sensors are consistent with being explained by collision excitation of H2O by O(3P), (2) diurnal variations of 4.5-9.5 micron intensities follow the model predicted O density for a full orbit, (3) daytime increases in the H2O cloud density were not evident, (4) the cross sections for the collisional excitation process are derived and compared to values computated by Johnson (1986) and Redmon et al. (1986), (5) theoretical investigation suggests greater than 60% of the radiation from H2O is a result of multiphoton emission resulting from collisional multiquanta excitation, and (6) the large daytime increase in the 1.7-3.0 micron intensity data suggests that O(+) may likely be instrumental in producing excited H2O(+) through charge exchange.

  8. Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: Low-lying states v(8) <= 2 of methyl cyanide, CH3CN

    SciTech Connect

    Muller, H. S.; Brown, Linda R.; Drouin, B. J.; Pearson, J. C.; Kleiner, Isabelle; Sams, Robert L.; Sung, Keeyoon; Ordu, Matthias H.; Lewen, Frank

    2015-06-01

    Rotational and rovibrational spectra of methyl cyanide were recorded to analyze interactions in low-lying vibrational states and to construct line lists for radio astronomical observations as well as for infrared spectroscopic investigations of planetary atmospheres. The rotational spectra cover large portions of the 36-1627 GHz region. In the infrared (IR), a spectrum was recorded for this study in the region of 2v(8) around 717 cm(-1) with assignments covering 684-765 cm-1. Additional spectra in the vs region were used to validate the analysis.

  9. Progress in the Rotational Analysis of the Ground and Low-Lying Vibrationally Excited States of Malonaldehyde

    NASA Astrophysics Data System (ADS)

    Goudreau, E. S.; Tokaryk, Dennis W.; Ross, Stephen Cary; Billinghurst, Brant E.

    2016-06-01

    Despite being an important prototype molecule for intramolecular proton tunnelling, the far-IR spectrum of the internally hydrogen-bonded species malonaldehyde (C_3O_2H_4) is not yet well understood. In the talk I gave at the ISMS meeting in 2015 I discussed the high-resolution spectra we obtained at the Canadian Light Source synchrotron in Saskatoon, Saskatchewan. These spectra include a number of fundamental vibrational bands in the 100-2000 cm-1 region. In our efforts to analyze these bands we have noticed that our ground state combination differences show a large drift (up to an order of magnitude larger than our experimental error) away from those calculated using constants established by Baba et al., particularly in regions of high J (above 30) and low Ka (below 5). An examination of the previous microwave and far-IR studies reveals that this region of J-Ka space was not represented in the lines that Baba et al. used to generate the values for their fitting parameters. By including our own measurements in the fitting, we were able to improve the characterization of the ground state so that it is now consistent with all of the existing data. This characterization now covers a much larger range of J-Ka space and has enabled us to make significant progress in analyzing our far-IR synchrotron spectra. These include an excited vibrational state at 241 cm-1 as well as several states split by the tunnelling effect at higher wavenumber. T. Baba, T. Tanaka, I. Morino, K. M. T. Yamada, K. Tanaka. Detection of the tunneling-rotation transitions of malonaldehyde in the submillimeter-wave region. J. Chem. Phys., 110. 4131-4133 (1999) P. Turner, S. L. Baughcum, S. L. Coy, Z. Smith. Microwave Spectroscopic Study of Malonaldehyde. 4. Vibration-Rotation Interaction in Parent Species. J. Am. Chem. Soc., 106. 2265-2267 (1984) D. W. Firth, K. Beyer, M. A. Dvorak, S. W. Reeve, A. Grushow, K. R. Leopold. Tunable far-infrared spectroscopy of malonaldehyde. J. Chem. Phys., 94. 1812

  10. Magnetic-dipole-to-electric-quadrupole cross-susceptibilities for relativistic hydrogenlike atoms in some low-lying discrete energy eigenstates

    NASA Astrophysics Data System (ADS)

    Stefańska, Patrycja

    2017-01-01

    In this paper we present tabulated data for magnetic-dipole-to-electric-quadrupole cross-susceptibilities (χ M 1 →E 2) for Dirac one-electron atoms with a pointlike, spinless and motionless nucleus of charge Ze. Numerical values of this susceptibility for the hydrogen atom (Z = 1) and for hydrogenic ions with 2 ⩽ Z ⩽ 137 are computed from the general analytical formula, recently derived by us (Stefanska, 2016), valid for an arbitrary discrete energy eigenstate. In this work we provide 30 tables with the values of χ M 1 →E 2 for the ground state, and also for the first, the second and the third set of excited states (i.e.: 2s1/2, 2p1/2, 2p3/2, 3s1/2, 3p1/2, 3p3/2, 3d3/2, 3d5/2, 4s1/2, 4p1/2, 4p3/2, 4d3/2, 4d5/2, 4f5/2 and 4f7/2) of the relativistic hydrogenlike atoms. The value of the inverse of the fine-structure constant used in the calculations is α-1 = 137.035999139, and was taken from CODATA 2014.

  11. Commissioning a Vibrating Wire System for Quadrupole Fiducialization

    SciTech Connect

    Levashov, Michael Y

    2010-12-03

    Quadrupoles will be placed between the undulator segments in LCLS to keep the electron beam focused as it passes through. The quadrupoles will be assembled with their respective undulator segments prior to being placed into the tunnel. Beam alignment will be used to center the quadrupoles, along with the corresponding undulators, on the beam. If there is any displacement between the undulator and the quadrupole axes in the assemblies, the beam will deviate from the undulator axis. If it deviates by more than 80{micro}m in vertical or 140{micro}m in horizontal directions, the undulator will not perform as required by LCLS. This error is divided between three sources: undulator axis fiducialization, quadrupole magnetic axis fiducialization, and assembly of the two parts. In particular, it was calculated that the quadrupole needs to be fiducialized to within 25{micro}m in both vertical and horizontal directions. A previous study suggested using a vibrating wire system for finding the magnetic axis of the quadrupoles. The study showed that the method has high sensitivity (up to 1{micro}m) and laid out guidelines for constructing such a system. There are 3 steps in fiducializing the quadrupole with the vibrating wire system. They are positioning the wire at the magnet center (step 1), finding the wire with position detectors (step 2), and finding the quadrupole tooling ball positions relative to the position detector tooling balls (step 3). A previous study investigated the error associated with each step by using a permanent quadrupole magnet on an optical mover system. The study reported an error of 11{micro}m for step 1 and a repeatability of 4{micro}m for step 2. However, the set up used a FARO arm to measure tooling balls and didn't allow to accurately check step 2 for errors; an uncertainty of 100{micro}m was reported. Therefore, even though the repeatability was good, there was no way to check that the error in step 2 was small. Following the recommendations of

  12. Doppler-shift attenuation method lifetime measurements of low-lying states in 111In

    NASA Astrophysics Data System (ADS)

    Bucurescu, D.; Căta-Danil, I.; Ilaş, G.; Ivaşcu, M.; Mărginean, N.; Stroe, L.; Ur, C. A.

    1996-11-01

    The lifetimes of nine low-lying excited states in 111In have been measured with the Doppler-shift attenuation method in the 111Cd(p,nγ) reaction. A comparison of experimental quantities with predictions based on the interacting boson-fermion model unravels the states due to the coupling of a g9/2 proton hole to the quadrupole vibrations of the core.

  13. Rotational Spectroscopy as a Tool to Investigate Interactions Between Vibrational Polyads in Symmetric Top Molecules: Low-Lying States v_8 ≤ 2 OF Methyl Cyanide

    NASA Astrophysics Data System (ADS)

    Müller, Holger S. P.; Ordu, Matthias H.; Lewen, Frank; Brown, Linda; Drouin, Brian; Pearson, John; Sung, Keeyoon; Kleiner, Isabelle; Sams, Robert

    2015-06-01

    Rotational and rovibrational spectra of methyl cyanide were recorded to analyze interactions in low-lying vibrational states and to construct line lists for radio astronomical observations as well as for infrared spectroscopic investigations of planetary atmospheres. The rotational spectra cover large portions of the 36-1627~GHz region. In the infrared (IR), a spectrum was recorded for this study in the region of 2ν_8 around 717~cm-1 with assignments covering 684-765~cm-1. Additional spectra in the ν _8 region were used to validate the analysis. Using ν _8 data as well as spectroscopic parameters for v_4 = 1, v_7 = 1, and v_8 = 3 from previous studies, we analyzed rotational data involving v = 0, v_8 = 1, and v_8 = 2 up to high J and K quantum numbers. We analyzed a strong Δ v_8 = ± 1, Δ K = 0, Δ l = ±3 Fermi resonance between v_8 = 1-1 and v_8 = 2+2 at K = 14 and obtained preliminary results for two further Fermi resonances between v_8 = 2 and 3. We also found resonant Δ v_8 = ± 1, Δ K = ∓ 2, Δ l = ± 1 interactions between v_8 = 1 and 2 and present the first detailed analysis of such a resonance between v_8 = 0 and 1. We discuss the impact of this analysis on the v_8 = 1 and 2 as well as on the axial v = 0 parameters and compare selected CH_3CN parameters with those of CH_3CCH and CH_3NC. We evaluated transition dipole moments of ν _8, 2ν _8 - ν _8, and 2ν _8 for remote sensing in the IR. Part of this work was carried out at the Jet Propulsion Laboratory under contract with the National Aeronautics and Space Administration. M. Koivusaari et al., J. Mol. Spectrosc. 152 (1992) 377-388. A.-M. Tolonen et al., J. Mol. Spectrosc. 160 (1993) 554-565.

  14. Vibrational Fingerprints of Low-Lying Pt(n)P(2n) (n = 1-5) Cluster Structures from Global Optimization Based on Density Functional Theory Potential Energy Surfaces.

    PubMed

    Jedidi, Abdesslem; Li, Rui; Fornasiero, Paolo; Cavallo, Luigi; Carbonniere, Philippe

    2015-12-03

    Vibrational fingerprints of small Pt(n)P(2n) (n = 1-5) clusters were computed from their low-lying structures located from a global exploration of their DFT potential energy surfaces with the GSAM code. Five DFT methods were assessed from the CCSD(T) wavenumbers of PtP2 species and CCSD relative energies of Pt2P4 structures. The eight first Pt(n)P(2n) isomers found are reported. The vibrational computations reveal (i) the absence of clear signatures made by overtone or combination bands due to very weak mechanical and electrical anharmonicities and (ii) some significant and recurrent vibrational fingerprints in correlation with the different PP bonding situations in the Pt(n)P(2n) structures.

  15. VIBRATION MEASUREMENTS IN A RHIC QUADRUPOLE AT CRYOGENIC TEMPERATURES.

    SciTech Connect

    JAIN, A.; AYDIN, S.; HE, P.; ANERELLA, M.; GANETIS, G.; HARRISON, M.; PARKER, B.; PLATE, S.

    2005-10-17

    One of the concerns in using compact superconducting magnets in the final focus region of the ILC is the influence of the cryogen flow on the vibration characteristics. As a first step towards characterizing such motion at nanometer levels, a project was undertaken at BNL to measure the vibrations in a spare RHIC quadrupole under cryogenic conditions. Given the constraints of cryogenic operation, and limited space available, it was decided to use a dual head laser Doppler vibrometer for this work. The performance of the laser vibrometer was tested in a series of room temperature tests and compared with results from Mark L4 geophones. The laser system was then used to measure the vibration of the cold mass of the quadrupole with respect to the outside warm enclosure. These measurements were carried out both with and without the flow of cold helium through the magnet. The results indicate only a minor increase in motion in the horizontal direction (where the cold mass is relatively free to move).

  16. Experimental determination of rotational constants of low-lying vibrational levels in the 0g- pure long-range state of ultracold Cs2 molecule

    NASA Astrophysics Data System (ADS)

    Wu, Jizhou; Liu, Wenliang; Li, Yuqing; Ma, Jie; Xiao, Liantuan; Jia, Suotang

    2017-04-01

    We report an accurate experimental determination of rotational constants of the lowest vibrational levels in the purely long-range state of ultracold cesium molecules (Cs2). We engineer a precise reference of the frequency difference through double photoassociation spectroscopy (PAS). The PAS for the lowest vibrational levels, v=0-3, has been obtained with an enhanced sensitivity and accuracy, according to which the binding energies have been corrected. As deduced from the reference, the frequency intervals between neighboring rotational levels are fitted to a non-rigid rotor model, thus the rotational constants are precisely obtained. The experimental results show good agreement with theoretical expectations.

  17. The origin of unequal bond lengths in the C1B2 state of SO2: Signatures of high-lying potential energy surface crossings in the low-lying vibrational structure

    DOE PAGES

    Park, G. Barratt; Jiang, Jun; Field, Robert W.

    2016-04-14

    Here the C1B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. The asymmetry in the potential energy surface is expressed as a staggering in the energy levels of the v'3 progression. We have recently made the first observation of low-lying levels with odd quanta of v'3, which allows us--in the current work--to characterize the origins of the level staggering. Our work demonstrates the usefulness of low-lying vibrational level structure, where the character of the wavefunctions can be relatively easily understood, to extract information about dynamicallymore » important potential energy surface crossings that occur at much higher energy. The measured staggering pattern is consistent with a vibronic coupling model for the double-minimum, which involves direct coupling to the bound 2 1A1 state and indirect coupling with the repulsive 3 1A1 state. The degree of staggering in the v'3 levels increases with quanta of bending excitation, which is consistent with the approach along the C state potential energy surface to a conical intersection with the 2 1A1 surface at a bond angle of ~145°.« less

  18. The origin of unequal bond lengths in the C ˜ 1B2 state of SO2: Signatures of high-lying potential energy surface crossings in the low-lying vibrational structure

    NASA Astrophysics Data System (ADS)

    Park, G. Barratt; Jiang, Jun; Field, Robert W.

    2016-04-01

    The C ˜ 1B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. The asymmetry in the potential energy surface is expressed as a staggering in the energy levels of the ν3' progression. We have recently made the first observation of low-lying levels with odd quanta of v3', which allows us—in the current work—to characterize the origins of the level staggering. Our work demonstrates the usefulness of low-lying vibrational level structure, where the character of the wavefunctions can be relatively easily understood, to extract information about dynamically important potential energy surface crossings that occur at much higher energy. The measured staggering pattern is consistent with a vibronic coupling model for the double-minimum, which involves direct coupling to the bound 2 1A1 state and indirect coupling with the repulsive 3 1A1 state. The degree of staggering in the ν3' levels increases with quanta of bending excitation, which is consistent with the approach along the C ˜ state potential energy surface to a conical intersection with the 2 1A1 surface at a bond angle of ˜145°.

  19. The origin of unequal bond lengths in the C̃ (1)B2 state of SO2: Signatures of high-lying potential energy surface crossings in the low-lying vibrational structure.

    PubMed

    Park, G Barratt; Jiang, Jun; Field, Robert W

    2016-04-14

    The C̃ (1)B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. The asymmetry in the potential energy surface is expressed as a staggering in the energy levels of the ν3(') progression. We have recently made the first observation of low-lying levels with odd quanta of v3('), which allows us-in the current work-to characterize the origins of the level staggering. Our work demonstrates the usefulness of low-lying vibrational level structure, where the character of the wavefunctions can be relatively easily understood, to extract information about dynamically important potential energy surface crossings that occur at much higher energy. The measured staggering pattern is consistent with a vibronic coupling model for the double-minimum, which involves direct coupling to the bound 2 (1)A1 state and indirect coupling with the repulsive 3 (1)A1 state. The degree of staggering in the ν3(') levels increases with quanta of bending excitation, which is consistent with the approach along the C̃ state potential energy surface to a conical intersection with the 2 (1)A1 surface at a bond angle of ∼145°.

  20. Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: Low-lying states v8 ⩽ 2 of methyl cyanide, CH3CN

    NASA Astrophysics Data System (ADS)

    Müller, Holger S. P.; Brown, Linda R.; Drouin, Brian J.; Pearson, John C.; Kleiner, Isabelle; Sams, Robert L.; Sung, Keeyoon; Ordu, Matthias H.; Lewen, Frank

    2015-06-01

    Rotational and rovibrational spectra of methyl cyanide were recorded to analyze interactions in low-lying vibrational states and to construct line lists for radio astronomical observations as well as for infrared spectroscopic investigations of planetary atmospheres. The rotational spectra cover large portions of the 36-1627 GHz region. In the infrared (IR), a spectrum was recorded for this study in the region of 2ν8 around 717 cm-1 with assignments covering 684-765 cm-1. Additional spectra in the ν8 region were used to validate the analysis. Information on the K level structure of CH3CN is almost exclusively obtained from IR spectra, as are basics of the J level structure. The large amount and the high accuracy of the rotational data improves knowledge of the J level structure considerably. Moreover, since these data extend to much higher J and K quantum numbers, they allowed us to investigate for the first time in depth local interactions between these states which occur at high K values. In particular, we have detected several interactions between v8 = 1 and 2. Notably, there is a strong Δv8 = ± 1 , ΔK = 0 , Δl = ± 3 Fermi resonance between v8 =1-1 and v8 =2+2 at K = 14 . Pronounced effects in the spectrum are also caused by resonant Δv8 = ± 1 , ΔK = ∓ 2 , Δl = ± 1 interactions between v8 = 1 and 2 at K = 13 , l = - 1 / K = 11 , l = 0 and at K = 15 , l = + 1 / K = 13 , l = + 2 . An equivalent resonant interaction occurs between K = 14 of the ground vibrational state and K = 12 , l = + 1 of v8 = 1 for which we present the first detailed account. A preliminary account was given in an earlier study on the ground vibrational state. Similar resonances were found for CH3CCH and, more recently, for CH3NC, warranting comparison of the results. From data pertaining to v8 = 2 , we also investigated rotational interactions with v4 = 1 as well as Δv8 = ± 1 , ΔK = 0 , Δl = ± 3 Fermi interactions between v8 = 2 and 3. We have derived N2- and self

  1. Shell model description of low-lying states in Po and Rn isotopes

    NASA Astrophysics Data System (ADS)

    Higashiyama, Koji; Yoshinaga, Naotaka

    2014-03-01

    Nuclear structure of the Po and Rn isotopes is theoretically studied in terms of the spherical shell model with the monopole- and quadrupole-pairing plus quadrupole-quadrupole effective interaction. The experimental energy levels of low-lying states are well reproduced. The shell model results are examined in detail in a pair-truncated shell model. The analysis reveals the alignment of two protons in the 0h9/2 orbital at spin 8.

  2. Set Up and Test Results for a Vibrating Wire System for Quadrupole Fiducialization

    SciTech Connect

    Levashov, Michael Y.

    2010-12-01

    Quadrupoles will be placed between the undulator segments in LCLS to keep the electron beam focused as it passes through. The quadrupoles will be assembled with their respective undulator segments prior to being placed into the tunnel. Beam alignment will be used to center the quadrupoles, along with the corresponding undulators, on the beam. If there is any displacement between the undulator and the quadrupole axes in the assemblies, the beam will deviate from the undulator axis. If it deviates by more than 80{micro}m in vertical or 140{micro}m in horizontal directions, the undulator will not perform as required by LCLS. This error is divided between three sources: undulator axis fiducialization, quadrupole magnetic axis fiducialization, and assembly of the two parts. In particular, it was calculated that the quadrupole needs to be fiducialized to within 25{micro}m in both vertical and horizontal directions. A previous study suggested using a vibrating wire system for finding the magnetic axis of a quadrupole. The study showed that the method has high sensitivity (up to 1{micro}m) and laid out guidelines for constructing it. There are 3 steps in fiducializing the quadrupole with the vibrating wire system. They are positioning the wire at the magnet center (step 1), finding the wire with position detectors (step 2), and finding the quadrupole tooling ball positions relative to the position detector tooling balls (step 3). The following break up of error was suggested for the fiducialization steps: 10{micro}m for step 1 (finding the center), 20{micro}m for step 2 (finding the wire), and 10{micro}m for step 3 (tooling ball measurements). The purpose of this study is to investigate whether the vibrating wire system meets the requirements for LCLS. In particular, if it can reliably fiducialize a quadrupole magnetic center to within 25{micro}m in both vertical and horizontal directions. The behavior of individual system components is compared to the expected performance

  3. Set Up and Test Results for a Vibrating Wire System for Quadrupole Fiducialization

    SciTech Connect

    Not Available

    2010-11-29

    Quadrupoles will be placed between the undulator segments in LCLS to keep the electron beam focused as it passes through. The quadrupoles will be assembled with their respective undulator segments prior to being placed into the tunnel. Beam alignment will be used to center the quadrupoles, along with the corresponding undulators, on the beam. If there is any displacement between the undulator and the quadrupole axes in the assemblies, the beam will deviate from the undulator axis. If it deviates by more than 80{micro}m in vertical or 140{micro}m in horizontal directions, the undulator will not perform as required by LCLS. This error is divided between three sources: undulator axis fiducialization, quadrupole magnetic axis fiducialization, and assembly of the two parts. In particular, it was calculated that the quadrupole needs to be fiducialized to within 25{micro}m in both vertical and horizontal directions. A previous study suggested using a vibrating wire system for finding the magnetic axis of a quadrupole. The study showed that the method has high sensitivity (up to 1{micro}m) and laid out guidelines for constructing it. There are 3 steps in fiducializing the quadrupole with the vibrating wire system. They are positioning the wire at the magnet center (step 1), finding the wire with position detectors (step 2), and finding the quadrupole tooling ball positions relative to the position detector tooling balls (step 3). The following break up of error was suggested for the fiducialization steps: 10{micro}m for step 1 (finding the center), 20{micro}m for step 2 (finding the wire), and 10{micro}m for step 3 (tooling ball measurements). The purpose of this study is to investigate whether the vibrating wire system meets the requirements for LCLS. In particular, if it can reliably fiducialize a quadrupole magnetic center to within 25{micro}m in both vertical and horizontal directions. The behavior of individual system components is compared to the expected performance

  4. Vibration Measurements to Study the Effect of Cryogen Flow in Superconducting Quadrupole.

    SciTech Connect

    He,P.; Anerella, M.; aydin, S.; Ganetis, G. Harrison, M.; Jain, A.; Parker, B.

    2007-06-25

    The conceptual design of compact superconducting magnets for the International Linear Collider final focus is presently under development. A primary concern in using superconducting quadrupoles is the potential for inducing additional vibrations from cryogenic operation. We have employed a Laser Doppler Vibrometer system to measure the vibrations in a spare RHIC quadrupole magnet under cryogenic conditions. Some preliminary results of these studies were limited in resolution due to a rather large motion of the laser head as well as the magnet. As a first step towards improving the measurement quality, a new set up was used that reduces the motion of the laser holder. The improved setup is described, and vibration spectra measured at cryogenic temperatures, both with and without helium flow, are presented.

  5. Fiducialization of the small-aperture quadrupoles based on the vibrating wire method

    NASA Astrophysics Data System (ADS)

    Wang, Baichuan; Zheng, Shuxin; Wu, Lin; Du, Changtong; Xing, Qingzi; Wang, Zhongming; Qiu, Mengtong; Wang, Xuewu

    2016-03-01

    A fiducialization method based on vibrating wire is described dedicated to the problem of locating the magnetic center relative to external fiducials for the small-aperture quadrupoles. The advantage of this method is that the measurement of the wire position, which may be the main error source, is no longer needed. The position of the magnetic center can be directly obtained by measuring the position shift of the magnet fiducials. This method has been validated on small Permanent Magnet Quadrupoles (PMQs). Experiments have confirmed its feasibility of measuring PMQs with good repeatability of about 10 μm, and shown its high sensitivity as well as convenience.

  6. High resolution photoelectron imaging of UO{sup −} and UO{sub 2}{sup −} and the low-lying electronic states and vibrational frequencies of UO and UO{sub 2}

    SciTech Connect

    Czekner, Joseph; Lopez, Gary V.; Wang, Lai-Sheng

    2014-12-28

    We report a study of the electronic and vibrational structures of the gaseous uranium monoxide and dioxide molecules using high-resolution photoelectron imaging. Vibrationally resolved photoelectron spectra are obtained for both UO{sup −} and UO{sub 2}{sup −}. The spectra for UO{sub 2}{sup −} are consistent with, but much better resolved than a recent study using a magnetic-bottle photoelectron analyzer [W. L. Li et al., J. Chem. Phys. 140, 094306 (2014)]. The electron affinity (EA) of UO is reported for the first time as 1.1407(7) eV, whereas a much more accurate EA is obtained for UO{sub 2} as 1.1688(6) eV. The symmetric stretching modes for the neutral and anionic ground states, and two neutral excited states for UO{sub 2} are observed, as well as the bending mode for the neutral ground state. These vibrational frequencies are consistent with previous experimental and theoretical results. The stretching vibrational modes for the ground state and one excited state are observed for UO. The current results for UO and UO{sub 2} are compared with previous theoretical calculations including relativistic effects and spin-orbit coupling. The accurate experimental data reported here provide more stringent tests for future theoretical methods for actinide-containing species.

  7. The origin of unequal bond lengths in the C1B2 state of SO2: Signatures of high-lying potential energy surface crossings in the low-lying vibrational structure

    SciTech Connect

    Park, G. Barratt; Jiang, Jun; Field, Robert W.

    2016-04-14

    Here the C1B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. The asymmetry in the potential energy surface is expressed as a staggering in the energy levels of the v'3 progression. We have recently made the first observation of low-lying levels with odd quanta of v'3, which allows us--in the current work--to characterize the origins of the level staggering. Our work demonstrates the usefulness of low-lying vibrational level structure, where the character of the wavefunctions can be relatively easily understood, to extract information about dynamically important potential energy surface crossings that occur at much higher energy. The measured staggering pattern is consistent with a vibronic coupling model for the double-minimum, which involves direct coupling to the bound 2 1A1 state and indirect coupling with the repulsive 3 1A1 state. The degree of staggering in the v'3 levels increases with quanta of bending excitation, which is consistent with the approach along the C state potential energy surface to a conical intersection with the 2 1A1 surface at a bond angle of ~145°.

  8. Low-lying excitations in 72Ni

    NASA Astrophysics Data System (ADS)

    Morales, A. I.; Benzoni, G.; Watanabe, H.; Nishimura, S.; Browne, F.; Daido, R.; Doornenbal, P.; Fang, Y.; Lorusso, G.; Patel, Z.; Rice, S.; Sinclair, L.; Söderström, P.-A.; Sumikama, T.; Wu, J.; Xu, Z. Y.; Yagi, A.; Yokoyama, R.; Baba, H.; Avigo, R.; Bello Garrote, F. L.; Blasi, N.; Bracco, A.; Camera, F.; Ceruti, S.; Crespi, F. C. L.; de Angelis, G.; Delattre, M.-C.; Dombradi, Zs.; Gottardo, A.; Isobe, T.; Kojouharov, I.; Kurz, N.; Kuti, I.; Matsui, K.; Melon, B.; Mengoni, D.; Miyazaki, T.; Modamio-Hoyborg, V.; Momiyama, S.; Napoli, D. R.; Niikura, M.; Orlandi, R.; Sakurai, H.; Sahin, E.; Sohler, D.; Shaffner, H.; Taniuchi, R.; Taprogge, J.; Vajta, Zs.; Valiente-Dobón, J. J.; Wieland, O.; Yalcinkaya, M.

    2016-03-01

    Low-lying excited states in 72Ni have been investigated in an in-flight fission experiment at the RIBF facility of the RIKEN Nishina Center. The combination of the state-of-the-art BigRIPS and EURICA setups has allowed for a very accurate study of the β decay from 72Co to 72Ni, and has provided first experimental information on the decay sequence 72Fe→72Co→72Ni and on the delayed neutron-emission branch 73Co→72Ni . Accordingly, we report nearly 60 previously unobserved γ transitions which deexcite 21 new levels in 72Ni. Evidence for the location of the so-sought-after (42+) ,(62+) , and (81+) seniority states is provided. As well, the existence of a low-spin β -decaying isomer in odd-odd neutron-rich Co isotopes is confirmed for mass A =72 . The new experimental information is compared to simple shell-model calculations including only neutron excitations across the f p g shells. It is shown that, in general, the calculations reproduce well the observed states.

  9. Global Correlations for Low-Lying Collective 2+ States

    NASA Astrophysics Data System (ADS)

    Qin, Z. Z.; Lei, Y.; Pittel, S.; Bijker, R.

    2017-07-01

    By using the triaxial rotor model and the anharmonic vibrator model with phonon mixing, we derive a global correlation between the quadrupole moments of the two lowest 2+ states in collective nuclei that had previously been observed in experimental data across the periodic table. We then derive other electromagnetic properties for these two models of nuclear structure and compare them globally with experimental data. We find that both models are able to robustly describe the experimental data across the region of nuclei for which the models are applicable, including a large number that they have in common. We then show that there seems to exists a robust orthogonal transformation between these two models for realistic nuclear systems, suggesting that these two seemingly diverse descriptions of quadrupole collective phenomena seem to act in a similar model space and may therefore have a common origin.

  10. Toward a Global Model of Low-Lying Vibrational States of CH_3CN: the v_4 = 1 State at 920 cm-1 and its Interactions with Nearby States

    NASA Astrophysics Data System (ADS)

    Müller, Holger S. P.; Drouin, B. J.; Pearson, J. C.; Brown, L. R.; Kleiner, I.; Sams, R. L.

    2010-06-01

    Methyl cyanide, CH_3CN, is an important interstellar molecule, in particular in hot and dense molecular cores, and it may play a role in the atmospheres of planets or of Titan. Therefore, we have recorded extensive rotational and rovibrational spectra up to ˜ 1.6 THz and ˜ 1500 cm-1, respectively. The present investigation extends our analysis of states with v_8 ≤ 2 at vibrational energies below 740 cm-1 and takes into consideration findings from an analysis of the ν _4 band and the higher-lying ν _7 (at ˜1042 cm-1) and 3ν _8 ^1 (at ˜1078 cm-1) bands. The rotational data extend to J = 87 and K = 15, infrared assignments currently extend to 55 and 12, respectively. Parameters affecting only v_7 = 1 or v_8 = 3 as well as some additional interaction parameters were kept fixed to values from (b). The largest perturbations of v_4 = 1 are caused by a Δ k = 0, Δ l = 3 interaction with v_8 = 3 at K = 8. Despite the inclusion of the interaction parameter and a centrifugal distortion correction, residuals amount to more than 200 MHz very close to the resonance. Removal of these residuals probably requires explicit inclusion of v_8 = 3 data. Several additional perturbations exist at lower as well as higher K with v_8 = 2, v_7 = 1 and v_8 = 3. Higher values of K are difficult to reproduce in spite of an extensive set of distortion parameters which, at highest orders, have rather large magnitudes, possibly indicating unaccounted interactions which would probably occur with states even higher than v_8 = 3. H. S. P. Müller et al., contribution WG03, presented at the 62nd International Symposium on Molecular Spectroscopy, June 18-22, 2007, Columbus, Ohio, USA. A.-M. Tolonen et al., J. Mol. Spectrosc. 160 (1993) 554-565.

  11. Ground-state and pairing-vibrational bands with equal quadrupole collectivity in 124Xe

    DOE PAGES

    Radich, A. J.; Garrett, P. E.; Allmond, J. M.; ...

    2015-04-01

    The nuclear structure of 124Xe has been investigated via measurements of the β+/EC decay of 124Cs with the 8π γ-ray spectrometer at the TRIUMF-ISAC facility. The data collected have enabled branching ratio measurements of weak, low-energy transitions from highly excited states, and the 2+ → 0+ in-band transitions have been observed. Combining these results with those from a previous Coulomb excitation study,more » $$B(E2; 2^+_3 → 0^+_2)$$ = 78(13) W.u. and $$B(E2; 2^+_4 → 0^+_3)$$ = 53(12) W.u. were determined. The $$0^+_3$$ state, in particular, is interpreted as the main fragment of the proton-pairing vibrational band identified in a previous 122Te(3He,n)124Xe measurement, and has quadrupole collectivity equal to, within uncertainty, that of the ground-state band.« less

  12. Spectroscopy of low-lying levels in 81Br and its nuclear-structure interpretation

    NASA Astrophysics Data System (ADS)

    Jakob, G.; Speidel, K.-H.; Kremeyer, S.; Busch, H.; Grabowy, U.; Gohla, A.; Cub, J.; Gerber, J.; Oros, A.-M.; Heyde, K.; Rikovska, J.

    1996-02-01

    Magnetic moments of low-lying levels in 81Br have been measured using Coulomb excitation of 81Br beams and the technique of transient magnetic fields with Gd as ferromagnet. In addition, lifetimes have been redetermined for several states employing the Doppler-shift attenuation method and mixing ratios of γ-transitions were deduced from angular correlations. The data are discussed in the framework of the particle-vibrator and the particle-rotor coupling models.

  13. On the low-lying states of TiC

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.; Siegbahn, P. E. M.

    1984-01-01

    The ground and low-lying excited states of TiC are investigated using a CASSCF-externally contracted CI approach. The calculations yield a 3Sigma(+) ground state, but the 1Sigma(+) state is only 780/cm higher and cannot be ruled out. The low-lying states have some triple bond character. The nature of the bonding and origin of the states are discussed.

  14. On the low-lying states of TiC

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.; Siegbahn, P. E. M.

    1984-01-01

    The ground and low-lying excited states of TiC are investigated using a CASSCF-externally contracted CI approach. The calculations yield a 3Sigma(+) ground state, but the 1Sigma(+) state is only 780/cm higher and cannot be ruled out. The low-lying states have some triple bond character. The nature of the bonding and origin of the states are discussed.

  15. Low-lying Gamow-Teller transitions in spherical nuclei

    SciTech Connect

    Cakmak, N.; Uenlue, S.; Selam, C.

    2012-01-15

    The Pyatov Method has been used to study the low-lying Gamow-Teller transitions in the mass region of 98 Less-Than-Or-Slanted-Equal-To A Less-Than-Or-Slanted-Equal-To 130. The eigenvalues and eigenfunctions of the total Hamiltonian have been solved within the framework of proton-neutron quasiparticle random-phase approximation. The low-lying {beta} decay log(ft) values have been calculated for the nuclei under consideration.

  16. γ -ray spectroscopy of low-lying excited states and shape competition in 194Os

    NASA Astrophysics Data System (ADS)

    Daniel, T.; Kisyov, S.; Regan, P. H.; Marginean, N.; Podolyák, Zs.; Marginean, R.; Nomura, K.; Rudigier, M.; Mihai, R.; Werner, V.; Carroll, R. J.; Gurgi, L. A.; Oprea, A.; Berry, T.; Serban, A.; Nita, C. R.; Sotty, C.; Suvaila, R.; Turturica, A.; Costache, C.; Stan, L.; Olacel, A.; Boromiza, M.; Toma, S.

    2017-02-01

    The properties of excited states in the neutron-rich nucleus 194Os have been investigated using the 192Os(18O,16O )194Os reaction with an 80 MeV beam provided by the IFIN-HH Laboratory, Bucharest. Discrete γ -ray decays from excited states have been measured using the hybrid HPGe-LaBr3(Ce ) array RoSPHERE. The current work identifies a number of previously unreported low-lying nonyrast states in 194Os as well as the first measurement of the half-life of the yrast 2+ state of 302(50) ps. This is equivalent to a B (E 2 :2+→0+) =45 (16 ) W.u. and intrinsic quadrupole deformation of βeff=0.14 (1 ) . The experimental results are compared with Hartree-Fock-Bogoliubov-interacting-boson-model calculations and are consistent with a reduction in a quadrupole collectivity in Os isotopes with increasing neutron number.

  17. RDDS lifetime measurements of low-lying superdeformed states in {sup 194}Hg

    SciTech Connect

    Kuehn, R.; Dewald, A.; Kruecken, R.

    1996-12-31

    The lifetimes of three low-lying states in the superdeformed (SD) yrast band of {sup 194}Hg were measured by the recoil-distance Doppler-shift method. The deduced transition quadrupole moments, Q{sub t}, equal those extracted from a DSAM measurement for the high-lying states of the band corroborate the assumption that the decay out of SD bands does not strongly affect the structure of the corresponding states. By a simple mixing-model the decay can be described assuming a very small admixture of normal-deformed (ND) states to the decaying SD states. The deduced ND mixing amplitudes for the yrast SD bands in {sup 192,194}Hg and {sup 194}Pb are presented along with average transition quadrupole moments for the lower parts of the excited SD bands.

  18. Low-lying dipole modes in 26,28Ne in the quasiparticle relativistic random phase approximation

    NASA Astrophysics Data System (ADS)

    Cao, Li-Gang; Ma, Zhong-Yu

    2005-03-01

    The low-lying isovector dipole strengths in the neutron-rich nuclei 26Ne and 28Ne are investigated in the quasiparticle relativistic random phase approximation. Nuclear ground-state properties are calculated in an extended relativistic mean field theory plus Bardeen-Cooper-Schrieffer (BCS) method where the contribution of the resonant continuum to pairing correlations is properly treated. Numerical calculations are tested in the case of isovector dipole and isoscalar quadrupole modes in the neutron-rich nucleus 22O. It is found that in the present calculation, low-lying isovector dipole strengths at Ex<10MeV in nuclei 26Ne and 26Ne exhaust about 4.9% and 5.8% of the Thomas-Reiche-Kuhn dipole sum rule, respectively. The centroid energy of the low-lying dipole excitation is located at 8.3 MeV in 26Ne and 7.9 MeV in 28Ne.

  19. Accurate ab initio calculations of the quadrupole moment of acetylene. A combined study of basis set, correlation, and vibrational effects

    NASA Astrophysics Data System (ADS)

    Lindh, R.; Liu, B.

    1991-03-01

    The quadrupole moment of acetylene has been studied at the multiconfiguration self-consistent field (MCSCF) and multireference single and double configuration interaction (MRSDCI) level of theory. At the MCSCF level the π-CI complete active space SCF (CASSCF) and the valence-CI CASSCF were employed. The subsequent MRSDCI calculations were continued until the reference space included all configuration state functions (CSFs) of the MCSCF wave function with a coefficient larger than 0.01 [MRSDCI(0.01)]. The higher level basis sets in this study were all based on van Duijneveldt's C(13s 8p) and H(6s) and extensions of that basis set. The study shows in a consistent way that both the one- and n-particle spaces are saturated at the highest level of theory. The study has revealed that in addition to the well known increase of the quadrupole moment due to the inclusion of polarizing functions in the basis (typically 0.20 a.u.), the inclusion of electronic correlation in the model wave function as well as vibrational corrections will decrease the quadrupole moment significantly more, -0.66, -0.49, and -0.36 a.u., for the correlation correction and zero-point correction for HCCH and DCCD, respectively. The most accurate computations predict the quadrupole moment of HCCH, including zero-point correction, to be 4.29±0.12 a.u., which discriminates the experimental estimates of 4.03±0.30, 4.28±0.30, and 4.57±0.30 a.u. (the first being the favored value). The quadrupole moment of DCCD is computed to 4.42±0.10 a.u. In the study it was observed that in contradiction to previous experiences the use of the model equilibrium geometries rather than the experimental geometry gives a smoother convergence as the level of theory is increased. The effects of basis set quality and electron correlation on the quadrupole moment are studied in detail. These effects are analyzed with reference to the redistribution of the electronic charge.

  20. The Low-Lying Electronic States of Mg2(+)

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Bauschlicher, Charles W., Jr.

    1994-01-01

    The low-lying doublet and quartet states of Mg+ have been studied using a multireference configuration interaction approach. The effect of inner-shell correlation has been included using the core-polarization potential method. The computed spectroscopic constants, lifetimes, and oscillator strengths should help resolve the difference between the recent experiments and previous theoretical calculations.

  1. Low-lying or malpositioned intrauterine devices and systems.

    PubMed

    Golightly, Ellen; Gebbie, Ailsa E

    2014-04-01

    The intrauterine device (IUD) and intrauterine system (IUS) are widely used forms of long-acting reversible contraception. Occasionally, IUD/IUS users have an ultrasound scan that shows a low-lying IUD/IUS or an IUD/IUS is found incidentally on scan to be low-lying within the uterus. No formal guidelines exist on the clinical implications of this scenario or the most appropriate management. We report here on a systematic review of the literature. A search of the online database PubMed was performed to identify articles relating to low-lying or malpositioned IUD/IUS. A total of 1101 articles was identified, and 15 were determined to be relevant to the research question. There is little published evidence to determine the nature and extent of the clinical relevance of a low-lying IUD. We recommend individualised management of these women, with particular caution in younger women and those with a history of previous IUD/IUS expulsion. Consideration may be given to attempting to readjust the IUD/IUS position, but if removal is performed, immediate replacement is essential if provision of alternative effective contraception has not been established.

  2. Clinicians' views on low-lying intrauterine devices or systems.

    PubMed

    Golightly, Ellen; Gebbie, Ailsa E

    2014-04-01

    There is a lack of consensus and very little published guidance on the management of a low-lying or malpositioned intrauterine contraceptive device (IUD) or system (IUS). A short e-mail questionnaire sent to senior medical staff working in contraceptive services confirmed the variation in views and management of this clinical area. Almost all respondents would replace an IUD/IUS lying either totally or partially in the cervical canal. The nearer the device was to the fundus the more likely respondents were to leave it in situ and there was less concern if the device was an IUS, presumably in view of the hormonal action. In the presence of abnormal bleeding or pain, most respondents would look for other causes rather than assume that the low-lying device was to blame. Respondents expressed uncertainty as to whether low-lying devices were more likely to fail or not and around half the respondents felt that low-lying devices could migrate upwards within the cavity. This survey highlighted the need for accurate evidence-based guidance to assist in this area of clinical contraceptive practice.

  3. Metastability of the low-lying electronic states of CBr2+: A CASSCF/MRCI study

    NASA Astrophysics Data System (ADS)

    Lins, Igor Araujo; Belinassi, Antonio Ricardo; Ornellas, Fernando Rei; Alves, Tiago Vinicius

    2017-08-01

    The metastability of the low-lying electronic states of CBr2+ correlating with the two lowest dissociation channels was investigated for the first time at a high level theoretical approach, SA-CASSCF/MRCI. Spin-orbit interaction changes substantially the profile of the potential energy curves, specially for the ground (X 2Σ+) and first excited (1 2 Π) states. The second adiabatic ionization energies are also determined and show an excelent agreement with the experimental derived values. Tunneling widths computed for the Ω bound states show that the lowest vibrational levels of components 1/2 are stable against tunneling.

  4. Theoretical Study of the Low-Lying States of MgN+2

    NASA Technical Reports Server (NTRS)

    Maitre, Philippe; Bauschlicher, Charles W., Jr.; Gross, Anthony R. (Technical Monitor)

    1994-01-01

    The structure and binding energies of the low-lying states of MgN2+ have been computed at the multireference configuration interaction level of theory. The effect of Mg inner-shell correlation have been included using the core-polarization potential method. The charge-quadrupole interaction results in a linear 2Sigma+ ground state as expected. The excited states can arise from either the interaction of the 2-P state of Mg+ with N2 or from charge transfer states with Mg(sup 2+)N2- bonding character. The lowest lying excited state, 2-B2, is mixture of these two mechanisms, which results in a C2v, geometry with Mg atoms sitting at the N2 bond midpoint. The small barrier in the bending potential exists between this state and the 2-II State which is the lowest lying linear excited state.

  5. Reduced transition strengths of low-lying yrast states in chromium isotopes in the vicinity of N =40

    NASA Astrophysics Data System (ADS)

    Braunroth, Thomas; Dewald, A.; Iwasaki, H.; Lenzi, S. M.; Albers, M.; Bader, V. M.; Baugher, T.; Baumann, T.; Bazin, D.; Berryman, J. S.; Fransen, C.; Gade, A.; Ginter, T.; Gottardo, A.; Hackstein, M.; Jolie, J.; Lemasson, A.; Litzinger, J.; Lunardi, S.; Marchi, T.; Modamio, V.; Morse, C.; Napoli, D. R.; Nichols, A.; Recchia, F.; Stroberg, S. R.; Wadsworth, R.; Weisshaar, D.; Whitmore, K.; Wimmer, K.

    2015-09-01

    Background: In neutron-rich nuclei around N =40 rapid changes in nuclear structure can be observed. While 68Ni exhibits signatures of a doubly magic nucleus, experimental data along the isotopic chains in even more exotic Fe and Cr isotopes—such as excitation energies and transition strengths—suggest a sudden rise in collectivity toward N =40 . Purpose: Reduced quadrupole transition strengths for low-lying transitions in neutron-rich 58,60,62Cr are investigated. This gives quantitative new insights into the evolution of quadrupole collectivity in the neutron-rich region close to N =40 . Method: The recoil distance Doppler-shift (RDDS) technique was applied to measure lifetimes of low-lying states in 58,60,62>Cr. The experiment was carried out at the National Superconducting Cyclotron Laboratory (NSCL) with the SeGA array in a plunger configuration coupled to the S800 magnetic spectrograph. The states of interest were populated by means of one-proton knockout reactions. Results: Data reveal a rapid increase in quadrupole collectivity for 58,60,62>Cr toward N =40 and point to stronger quadrupole deformations compared to neighboring Fe isotopes. The experimental B (E 2 ) values are reproduced well with state-of-the-art shell-model calculations using the LNPS effective interaction. A consideration of intrinsic quadrupole moments and B42 ratios suggest an evolution toward a rotational nature of the collective structures in Cr,6260. Compared to 58Cr, experimental B42 and B62 values for 60Cr are in better agreement with the E (5 ) limit. Conclusion: Our results indicate that collective excitations in neutron-rich Cr isotopes saturate at N =38 , which is in agreement with theoretical predictions. More detailed experimental data of excited structures and interband transitions are needed for a comprehensive understanding of quadrupole collectivity close to N =40 . This calls for additional measurements in neutron-rich Cr and neighboring Ti and Fe nuclei.

  6. Noncollisional excitation of low-lying states in gaseous nebulae

    NASA Technical Reports Server (NTRS)

    Rubin, Robert H.

    1986-01-01

    Consideration is given to the effects of processes other than electron collisional excitation on the energy level populations of species of C, N, and O. It is found that dielectronic as well as direct-radiative recombination may contribute significantly and in some cases be the major input to populating the low-lying metastable levels. It is concluded that the most pronounced changes occur when there is a large effective recombination coefficient to a level and when T(e) is low. The most dramatic change among the forbidden lines occurs for the O II forbidden lines.

  7. On properties of low-lying spin-1 hadron resonances

    NASA Astrophysics Data System (ADS)

    Chizhov, M. V.

    2017-03-01

    Properties of low-lying spin-1 hadron resonances are described in the review. It is shown how the Nambu-Jona-Lasinio model can be extended in the chiral invariant way by new tensor interactions. New mass formulas are obtained, which are not based on unitary symmetry groups but involve particles from different multiplets even with opposite parity. They all are in good agreement with experimental data. Dynamic properties of spin-1 mesons confirmed by the calculations performed using the QCD sum rule technique and the lattice calculations are understood and explained.

  8. The low-lying electronic states of MgO

    NASA Astrophysics Data System (ADS)

    Bauschlicher, Charles W.; Schwenke, David W.

    2017-09-01

    The low-lying singlet and triplet states of MgO have been studied using a SA-CASCF/IC-MRCI approach using the aug-cc-pV5Z basis set. The spectroscopic constants (re,ωe , and Te) are in good agreement with the available experimental data. The computed lifetime for the B state is in excellent agreement with two of the three experimental results. The d state lifetime is in good agreement with experiment, while the computed D state lifetime is about twice as long as experiment.

  9. The low-lying electronic states of ReB.

    PubMed

    Borin, Antonio Carlos; Gobbo, João Paulo; Castro, César Augusto Milani

    2014-07-01

    The ground and low-lying electronic states of ReB were studied at the CASPT2//CASSCF level (multiconfigurational second-order perturbation theory) and quadruple-ζ ANO-RCC basis sets. Spectroscopic constants, potential energy curves, wavefunctions, and Mulliken population analysis are given. The ground state of ReB is of X(5)Σ(+) symmetry (R e  = 1.817 Å, ω e  = .909 cm(-1), and μ = 2.87 D), giving rise to a Ω = 0(+) ground state after including spin-orbit coupling.

  10. Low-lying Collective States in {sup 136}Ba

    SciTech Connect

    Scheck, M.; Mukhopadhyay, S.; Crider, B.; Choudry, S. N.; Elhami, E.; Peters, E. E.; McEllistrem, M. T.; Orce, J. N.; Yates, S. W.

    2009-01-28

    Low-lying collective states in {sup 136}Ba were investigated with (n,n'{gamma}) techniques, including Doppler-shift attenuation lifetime measurements. The level spins, lifetimes, branching ratios, multipole-mixing ratios and transition strengths reveal candidates for symmetric-phonon states up to third order. The 2{sub ms}{sup +} mixed-symmetry state was confirmed as unfragmented and a candidate for a [2{sub 1}{sup +} x 2{sub ms}{sup +}]{sub 3}{sup +} two-phonon mixed-symmetry state is proposed.

  11. Fine and hyperfine structure in three low-lying 3S+ states of molecular hydrogen

    NASA Astrophysics Data System (ADS)

    Minaev, Boris; Loboda, Oleksandr; Rinkevicius, Zilvinas; Vahtras, Olav; Ågren, Hans

    The fine structure constant (electron spin-spin coupling) and the hyperfine structure parameters (electron-nuclear spin coupling, including spin-rotation and electron-nuclear quadrupole coupling) in the low-lying triplet states and of molecular hydrogen and deuterium are calculated using a recently developed technique with full configu-ration interaction and multiconfiguration self-consistent field wave functions. The second-order spin-orbit coupling contribution to the 3Σ+ states splitting is negligible, and the calculations therefore provide a good estimate of the zero-field splitting based only on the electron spin-spin coupling values. For the bound state a negligible zero-field splitting is found, in qualitative agreement with the e-a spectrum. The zero-field splitting parameter is considerable for the repulsive state (≃1 cm-1) and of intermediate size for the bound state. The isotropic hyperfine coupling constant is very large not only for the valence state (1580 MHz) but also for the Rydberg a and e triplet states (≃1400 MHz). The quadrupole coupling constants for the deuterium isotopes are negligible (0.04-0.07 MHz) for all studied triplet states. The electric dipole activity of the spin sublevels in the triplet-singlet transitions to the ground state is estimated by means of the quadratic response technique.

  12. Full configuration interaction calculation of the low lying valence and Rydberg states of BeH.

    PubMed

    Pitarch-Ruiz, J; Sánchez-Marín, J; Velasco, A M

    2008-03-01

    The all-electron full configuration interaction (FCI) vertical excitation energies for some low lying valence and Rydberg excited states of BeH are presented in this article. A basis set of valence atomic natural orbitals has been augmented with a series of Rydberg orbitals that have been generated as centered onto the Be atom. The resulting basis set can be described as 4s2p1d/2s1p (Be/H) + 4s4p3d. It allows to calculate Rydberg states up to n= {3,4,5} of the s, p, and d series of Rydberg states. The FCI vertical ionization potential for the same basis set and geometry amounts to 8.298 eV. Other properties such as FCI electric dipole and quadrupole moments and FCI transition dipole and quadrupole moments have also been calculated. The results provide a set of benchmark values for energies, wave functions, properties, and transition properties for the five electron BeH molecule. Most of the states have large multiconfigurational character in spite of their essentially single excited nature and a number of them present an important Rydberg-valence mixing that is achieved through the mixed nature of the particle MO of the single excitations.

  13. Vibration study of the APS storage ring 0. 8 meter quadrupole magnet/magnet support assembly

    SciTech Connect

    Jendrzejczyk, J.A.; Wambsganss, M.W.; Smith, R.K.

    1991-06-01

    The objectives of this study are as follows: Determine the vibration characteristics (frequency, damping, and mode shapes) of the magnet on prototypic supports (the actual mounting system used to mount the magnet on the girder). Measure system response to ambient floor motion. Measure the effect of various modifications to determine if the magnet response can be modified to minimize unwanted response characteristics. Modifications investigated include support schemes, increasing system damping, and increasing mechanical rigidity. Measure system response to coolant flow. Determine vibrational characteristics of a large concrete block placed on a concrete floor, including response to ambient floor motions.

  14. Novel triaxial structure in low-lying states of neutron-rich nuclei around A ≈100

    NASA Astrophysics Data System (ADS)

    Xiang, J.; Yao, J. M.; Fu, Y.; Wang, Z. H.; Li, Z. P.; Long, W. H.

    2016-05-01

    Background: In recent years, the study of triaxiality in the low-lying states of atomic nuclei with transition character or shape coexistence has been of great interest. Previous studies indicate that the neutron-rich nuclei in the A ˜100 mass region with Z ˜40 ,N ˜60 serve as good grounds for examining the role of triaxiality in nuclear low-lying states. Purpose: The aim of this work is to provide a microscopic study of low-lying states for nuclei in the A ˜100 mass regions and to examine in detail the role of triaxiality in the shape-coexistence phenomena and the variation of shape with the isospin and spin values at the beyond mean-field level. Method: The starting point of our method is a set of relativistic mean-field plus BCS wave functions generated with a constraint on triaxial deformations (β ,γ ) . The excitation energies and electric multipole transition strengths of low-lying states are calculated by solving a five-dimensional collective Hamiltonian (5DCH) with parameters determined by the mean-field wave functions. Results: The low-lying states of Mo isotopes and of N =60 isotones in the A ˜100 mass region are calculated. The results indicate that triaxiality is essential to reproduce the data of excitation energies and electric quadrupole transition strengths in low-lying states and plays an important role in the shape evolution as a function of nucleon number. However, the decrease of nuclear collectivity with the increase of angular momentum in neutron-rich Mo isotopes has not been reproduced. Conclusions: The evolution of nuclear collectivity in the low-lying states of neutron-rich nuclei in the A ˜100 mass region as a function of nucleon number is governed by the novel triaxial structure. However, the mechanism that governs the variation of nuclear shape with spin in Mo isotopes remains unclear and deserves further investigation by taking into account the effects other than the collective motions.

  15. Mapping quadrupole collectivity in the Cd isotopes: The breakdown of harmonic vibrational motion

    SciTech Connect

    Garrett, P. E.; Green, K. L.; Bangay, J.; Varela, A. Diaz; Sumithrarachchi, C. S.; Bandyopadhyay, D. S.; Bianco, L.; Demand, G. A.; Finlay, P.; Grinyer, G. F.; Leach, K. G.; Phillips, A. A.; Schumaker, M. A.; Svensson, C. E.; Wong, J.; Austin, R. A. E.; Colosimo, S.; Ball, G. C.; Garnsworthy, A. B.; Hackman, G.

    2011-10-28

    The stable Cd isotopes have long been used as paradigms for spherical vibrational motion. Extensive investigations with in-beam {gamma} spectroscopy have resulted in very-well-established level schemes, including many lifetimes or lifetime limits. A programme has been initiated to complement these studies with very-high-statistics {beta} decay using the 8{pi} spectrometer at the TRIUMF radioactive beam facility. The decays of {sup 112}In and {sup 112}Ag have been studied with an emphasis on the observation of, or the placement of stringent limits on, low-energy branches between potential multi-phonon levels. A lack of suitable 0{sup +} or 2{sup +} three-phonon candidates has been revealed. Further, the sum of the B(E2) strength from spin 0{sup +} and 2{sup +} states up to 3 MeV in excitation energy to the assigned two-phonon levels falls far short of the harmonic-vibrational expectations. This lack of strength points to the failing of collective models based on vibrational phonon structures.

  16. Ozone absorption spectroscopy in search of low-lying electronic states

    NASA Technical Reports Server (NTRS)

    Anderson, S. M.; Mauersberger, K.

    1995-01-01

    A spectrometer capable of detecting ozone absorption features 9 orders of magnitude weaker than the Hartley band has been employed to investigate the molecule's near-infrared absorption spectrum. At this sensitivity a wealth of information on the low-lying electronically excited states often believed to play a role in atmospheric chemistry is available in the form of vibrational and rotational structure. We have analyzed these spectra using a combination of digital filtering and isotope substitution and find evidence for three electronically excited states below 1.5 eV. The lowest of these states is metastable, bound by approximately 0.1 eV and probably the (3)A2 rather than the (3)B2 state. Its adiabatic electronic energy is 1.24 +/- 0.01 eV, slightly above the dissociation energy of the ground state. Two higher states, at 1.29 +/- 0.03 and 1.48 +/- 0.03 eV are identified as the (3)B2 and the (3)B1, respectively. Combined with other recent theoretical and experimental data on the low-lying electronic states of ozone, these results imply that these are, in fact, the lowest three excited states; that is, there are no electronically excited states of ozone lying below the energy of O(3P) + O2((3)Sigma(-), v = 0). Some of the implications for atmospheric chemistry are considered.

  17. On the low lying singlet states of BeO

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.; Lengsfield, B. H.; Yarkony, D. R.

    1980-01-01

    Calculations of the ground and low-lying singlet states of BeO are performed in order to gain an understanding of the techniques needed to treat the excited states of other, more complex, ionic molecules. The MCSCF and CI calculations are based on a Gaussian basis set of slightly better than double zeta plus polarization quality for single configuration descriptions of the states. The calculated X-A and X-B state separations are found to be in agreement with experimental measurements. The 1 Sigma - and 1 Delta states are predicted to lie approximately 40,000 kaysers above the ground state and are identified as the C and D states.The 2 1 Pi state is found to be approximately 15,000 kaysers and the 3 1 Sigma + state is found to be approximately 65,000 kaysers above the ground state.

  18. Instanton contributions to the low-lying hadron mass spectrum

    NASA Astrophysics Data System (ADS)

    Thomas, Samuel D.; Kamleh, Waseem; Leinweber, Derek B.

    2015-11-01

    The role of instanton-like objects in the QCD vacuum on the mass spectrum of low-lying light hadrons is explored in lattice QCD. Using overimproved stout-link smearing, tuned to preserve instanton-like objects in the QCD vacuum, the evolution of the mass spectrum under smearing is examined. The calculation is performed using a 203×40 dynamical fat-link-irrelevant-clover (FLIC) fermion action ensemble with lattice spacing 0.126 fm. Through the consideration of a range of pion masses, the effect of the vacuum instanton content is compared at a common pion mass. While the qualitative features of ground-state hadrons are preserved on instanton-dominated configurations, the excitation spectrum experiences significant changes. The underlying physics revealed shows little similarity to the direct-instanton-interaction predictions of the instanton liquid model.

  19. Ground-state and pairing-vibrational bands with equal quadrupole collectivity in 124Xe

    SciTech Connect

    Radich, A. J.; Garrett, P. E.; Allmond, J. M.; Andreoiu, C.; Ball, G. C.; Bianco, L.; Bildstein, V.; Chagnon-Lessard, S.; Cross, D. S.; Demand, G. A.; Diaz Varela, A.; Dunlop, R.; Finlay, P.; Garnsworthy, A. B.; Hackman, G.; Hadinia, B.; Jigmeddorj, B.; Laffoley, A. T.; Leach, K. G.; Michetti-Wilson, J.; Orce, J. N.; Rajabali, M. M.; Rand, E. T.; Starosta, K.; Sumithrarachchi, C. S.; Svensson, C. E.; Triambak, S.; Wang, Z. M.; Wood, J. L.; Wong, J.; Williams, S. J.; Yates, S. W.

    2015-04-01

    The nuclear structure of 124Xe has been investigated via measurements of the β+/EC decay of 124Cs with the 8π γ-ray spectrometer at the TRIUMF-ISAC facility. The data collected have enabled branching ratio measurements of weak, low-energy transitions from highly excited states, and the 2+ → 0+ in-band transitions have been observed. Combining these results with those from a previous Coulomb excitation study, $B(E2; 2^+_3 → 0^+_2)$ = 78(13) W.u. and $B(E2; 2^+_4 → 0^+_3)$ = 53(12) W.u. were determined. The $0^+_3$ state, in particular, is interpreted as the main fragment of the proton-pairing vibrational band identified in a previous 122Te(3He,n)124Xe measurement, and has quadrupole collectivity equal to, within uncertainty, that of the ground-state band.

  20. Signature to detect the isovector giant quadrupole resonance

    NASA Astrophysics Data System (ADS)

    Speth, J.; Cha, D.; Klemt, V.; Wambach, J.

    1985-06-01

    We calculate the γ decay from the isoscalar and isovector giant quadrupole resonances in 208Pb into the low-lying spectrum. Whereas the γ decay from the isoscalar giant quadrupole resonance into the first excited 3- state is very small, the corresponding transition from the isovector giant quadrupole resonance is strongly enhanced. According to preliminary calculations, these results hold rather generally for other heavy mass nuclei. We suggest using this property in experimental investigation of the isovector giant quadrupole resonance.

  1. Theoretical characterization of low-lying electronic states of FCO

    NASA Astrophysics Data System (ADS)

    Francisco, Joseph S.; Goldstein, Avery N.; Robb, Michael A.; Williams, Ian H.

    1992-03-01

    The electronic and vibrational spectra of the fluoroformyl radical FCO are discussed in the light of ab initio (CASSCF(5 in 4)/6-31+G* and UMP2/6-311G*) calculated adiabatic and vertical transition energies, and vibrational frequencies, for the X 2A', A 2A″, B 2A', and C 2A″ states. Results for the formyl radical HCO are also presented for comparison.

  2. On the low-lying states of CuO

    NASA Technical Reports Server (NTRS)

    Bagus, P. S.; Nelin, C. J.; Bauschlicher, C. W., Jr.

    1984-01-01

    Self consistent field and correlated wave functions have been computed for the ground and for several low-lying states of CuO. The ground state is X(2)PI and the lowest excited state, at approximately 8,000/cm above X(2)PI, is a previously unidentified 2-sigma(+) state. The separation of these states is compared to that for the similar states of KO and is analysed in terms of integrals between orbitals of the separated free ions. A classification of the states of the molecule based on states of Cu(+) and O(-) which leads to a division into manifolds of states arising from Cu(+) 3d(10) and Cu(+) 3d(9) 4s(1) is considered. It is predicted that the state of the 3d(9) 4s(1) manifold are 10,000 to 30,000/cm above the ground state and assign the observed A2-sigma(+) state at 16,500/cm to this manifold.

  3. Low-lying excitations in a strongly interacting Fermi gas

    NASA Astrophysics Data System (ADS)

    Vale, Christopher; Hoinka, Sascha; Dyke, Paul; Lingham, Marcus

    2016-05-01

    We present measurements of the low-lying excitation spectrum of a strongly interacting Fermi gas across the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensate (BEC) crossover using Bragg spectroscopy. By focussing the Bragg lasers onto the central volume of the cloud we can probe atoms at near-uniform density allowing measurement of the homogeneous density-density response function. The Bragg wavevector is set to be approximately half of the Fermi wavevector to probe the collective response. Below the superfluid transition temperature the Bragg spectra dominated by the Bogoliubov-Anderson phonon mode. Single particle excitations become visible at energies greater than twice the pairing gap. As interactions are tuned from the BCS to BEC regime the phonon and single particle modes separate apart and both the pairing gap and speed of sound can be directly read off in certain regions of the crossover. Single particle pair-breaking excitations become heavily suppressed as interactions are tuned from the BCS to BEC regimes.

  4. Configuration mixing in low-lying spectra of carbon hypernuclei

    NASA Astrophysics Data System (ADS)

    Xia, HaoJie; Mei, Hua; Yao, JiangMing

    2017-10-01

    We perform a coupled-channels study of the low-lying states in $^{13,15,17,19}_{~~~~~~~~~~~~~~~~~~~~~\\Lambda}$C with a covariant energy density functional based microscopic particle-core coupling model. The energy differences of $1/2^-$ and $3/2^-$ states in $^{13}_\\Lambda$C and $^{15}_\\Lambda$C are predicted to be 0.25 MeV and 0.34 MeV, respectively. We find that configuration mixings in the $1/2^-$ and $3/2^-$ states of $^{15}_\\Lambda$C are the weakest among those of $^{13,15,17,19}_{~~~~~~~~~~~~~~~~~~~~~\\Lambda}$C. It indicates that $^{15}_\\Lambda$C provides the best candidate among the carbon hypernuclei to study the spin-orbit splitting of $p_\\Lambda$ hyperon state.

  5. Spectroscopic strengths of low-lying levels in 18Ne

    NASA Astrophysics Data System (ADS)

    Omalley, Patrick; Allen, J. M.; Bardayan, D. W.; Becchetti, F. D.; Cizewski, J. A.; Febbraro, M.; Gryzwacz, R.; Hall, M.; Jones, K. L.; Kolata, J. J.; Paulauskas, S. V.; Smith, K.; Thornsberry, C.

    2016-09-01

    Much effort has been made to understand the origins of 18F in novae. Due to its relatively long half-life ( 2 hours), 18F can survive until the nova envelope is transparent, and therefore it can provide a sensitive diagnostic of nova nucleosynthesis. It is likely produced through the beta decay of 18Ne, which is itself produced (primarily) through the 17F(p, γ) reaction. Understanding the direct capture contribution to the 17F(p, γ) reaction is important to accurately model it. As such, the spectroscopic strengths of low-lying states in 18Ne are needed. At the University of Notre Dame a measurement of the 17F(d,n) reaction has been performed using a beam produced with TwinSol Low energy radioactive beam facility. The neutrons were detected using a combination of VANDLE and UoM deuterated scintillator arrays. Data will be shown and preliminary results discussed. Research sponsored by the National Science Foundation, the US DOE Office of Nuclear Physics, and the National Nuclear Security Administration.

  6. Low-lying isomeric levels in 75Cu

    SciTech Connect

    Daugas, J. M.; Faul, T.; Grawe, H.; Pfutzner, M.; Grzywacz, R.; Lewitowicz, M.; Achouri, N. L.; Bentida, R.; Beraud, R.; Borcea, C.; Bingham, C. R.; Catford, W.; Emsallem, A.; De France, G.; Grzywacz, K. L.; Lemmon, R.; Lopez Jimenez, M. J.; de Oliveira Santos, F.; Regan, P. H.; Rykaczewski, Krzysztof Piotr; Sauvestre, J. E.; Sawicka, M.; Stanoiu, M.; Sieja, K.; Nowacki, F.

    2010-01-01

    Isomeric low-lying states were identified and investigated in the 75Cu nucleus. Two states at 61.8(5)- and 128.3(7)-keV excitation energies with half-lives of 370(40)- and 170(15)-ns were assigned as 75m1Cu and 75m2Cu, respectively. The measured half-lives combined with the recent spin assignment of the ground state allow one to deduce tentatively spin and parity of the two isomers and the dominant multipolarities of the isomeric transitions with respect to the systematics of the Cu isotopes. Shell-model calculations using an up-to-date effective interaction reproduce the evolution of the 1/2 , 3/2 , and 5/2 states for the neutron-rich odd-mass Cu isotopes when filling the g9/2. The results indicate a significant change in the nuclear structure in this region, where a single-particle 5/2 state coexists with more and more collective 3/2 and 1/2 levels at low excitation energies.

  7. Low-lying isomeric levels in {sup 75}Cu

    SciTech Connect

    Daugas, J. M.; Faul, T.; Sauvestre, J. E.; Grawe, H.; Pfuetzner, M.; Sawicka, M.; Grzywacz, R.; Lewitowicz, M.; France, G. de; Lopez Jimenez, M. J.; Oliveira Santos, F. de; Baiborodin, D.; Bentida, R.; Beraud, R.; Emsallem, A.; Bingham, C. R.; Grzywacz, K. L.

    2010-03-15

    Isomeric low-lying states were identified and investigated in the {sup 75}Cu nucleus. Two states at 61.8(5)- and 128.3(7)-keV excitation energies with half-lives of 370(40)- and 170(15)-ns were assigned as {sup 75m1}Cu and {sup 75m2}Cu, respectively. The measured half-lives combined with the recent spin assignment of the ground state allow one to deduce tentatively spin and parity of the two isomers and the dominant multipolarities of the isomeric transitions with respect to the systematics of the Cu isotopes. Shell-model calculations using an up-to-date effective interaction reproduce the evolution of the 1/2{sup -}, 3/2{sup -}, and 5/2{sup -} states for the neutron-rich odd-mass Cu isotopes when filling the nug{sub 9/2}. The results indicate a significant change in the nuclear structure in this region, where a single-particle 5/2{sup -} state coexists with more and more collective 3/2{sup -} and 1/2{sup -} levels at low excitation energies.

  8. Modified particle-rotor model and low-lying rotational bands in odd-A triaxial nuclei

    NASA Astrophysics Data System (ADS)

    Modi, Swati; Patial, M.; Arumugam, P.; Maglione, E.; Ferreira, L. S.

    2017-09-01

    The low-lying rotational bands of triaxially deformed nuclei 137Pr, 137Pm and 139Eu are studied with a modified particle-rotor model following the nonadiabatic quasiparticle approach. The matrix elements of the odd-A nucleus are obtained in terms of a coupling matrix and the rotational energies of the even-even core. The spectra of the cores 136Ce, 136Nd and 138Sm indicate a strong influence of triaxial deformation and vibrational degrees of freedom. These properties are appropriately carried forward to the calculations for the odd-A nucleus. We demonstrate that the ground and side bands of the odd-A nucleus and its core can be explained with the same set of deformation parameters ({β }2, γ). We argue that this method could be useful in studying the low-lying states in exotic nuclei also.

  9. Microscopic analysis of quadrupole-octupole shape evolution

    NASA Astrophysics Data System (ADS)

    Nomura, Kosuke

    2015-05-01

    We analyze the quadrupole-octupole collective states based on the microscopic energy density functional framework. By mapping the deformation constrained self-consistent axially symmetric mean-field energy surfaces onto the equivalent Hamiltonian of the sdf interacting boson model (IBM), that is, onto the energy expectation value in the boson coherent state, the Hamiltonian parameters are determined. The resulting IBM Hamiltonian is used to calculate excitation spectra and transition rates for the positive- and negative-parity collective states in large sets of nuclei characteristic for octupole deformation and collectivity. Consistently with the empirical trend, the microscopic calculation based on the systematics of β2 - β3 energy maps, the resulting low-lying negative-parity bands and transition rates show evidence of a shape transition between stable octupole deformation and octupole vibrations characteristic for β3-soft potentials.

  10. On the ground and some low-lying excited states of ScB: A multiconfigurational study

    NASA Astrophysics Data System (ADS)

    Černušák, Ivan; Dallos, Michal; Lischka, Hans; Müller, Thomas; Uhlár, Milan

    2007-06-01

    The electronic structure of a series of low-lying excited triplet and quintet states of scandium boride (ScB) was examined using multireference configuration interaction (including Davidson's correction for quadruple excitations) and single-reference coupled cluster (CC) methods with averaged natural orbital (ANO) basis sets. The CC approach was used only for the lowest quintet state. The authors have analyzed eight low-lying triplets Σ-3(2), Σ+3, Π3(3), and Δ3(2) dissociating to Sc(D2)/B(P2) atoms and eight low-lying quintet states Σ-5, Σ+5, Π5(2), Φ5, and Δ5(3) dissociating to Sc(F4)/B(P2) atoms. They report the potential energy curves and spectroscopic parameters of ScB obtained with the multireference configuration interaction (MRCI) technique including all singly and doubly excited configurations obtained with the ANO-S basis set. For the two lowest states they obtained also improved ANO-L spectroscopic constants, dipole and quadrupole moments as well as scalar relativistic effects based on the Douglas-Kroll-Hess Hamiltonian. They provide the analysis of the bonding based on Mulliken populations and occupation numbers. Since the two lowest states, Σ-3 and Σ-5, lie energetically very close, their principal goal was to resolve the nature of the ground state of ScB. Their nonrelativistic MRCI(Q) (including Davidson correction) results indicate that the quintet is more stable than the triplet by about 800cm-1. Inclusion of scalar relativistic effects reduces this difference to about 240cm-1. The dissociation energies for Σ-5 ScB range from 3.20to3.30eV while those for the Σ-3 range from 1.70to1.80eV.

  11. Nuclear structure of low-lying states in 60,62,64,66Zn — A shell model description

    NASA Astrophysics Data System (ADS)

    Rai, S.; Biswas, A.; Mukherjee, B.

    2016-11-01

    Shell model calculation has been performed for even-even 60,62,64,66Zn using NuShellX code in f5/2pg9/2 model space with two different effective Hamiltonians, viz. JUN45 and jj44b. The low-lying structure is studied up to angular momentum, I = 10ℏ by calculating level energies, reduced transition probabilities, occupation numbers, lifetimes, and quadrupole moments. The results of the calculations are compared with the available experimental data. It is observed that the inclusion of 1g9/2 orbital in the model space is essential to understand nuclear structure in these isotopes. Shell model calculation with an improved set of effective Hamiltonian parameters and inclusion of 1f7/2 orbital in the model space are necessary in order to produce finer agreement with the experimental observations.

  12. Description of nuclear octupole and quadrupole deformation close to axial symmetry: Octupole vibrations in the X(5) nuclei Nd150 and Sm152

    NASA Astrophysics Data System (ADS)

    Bizzeti, P. G.; Bizzeti-Sona, A. M.

    2010-03-01

    The model, introduced in a previous paper, for the description of the octupole and quadrupole degrees of freedom in conditions close to the axial symmetry is used to describe the negative-parity band based on the first octupole vibrational state in nuclei close to the critical point of the U(5)-to-SU(3) phase transition. The situation of Nd150 and Sm152 is discussed in detail. The positive-parity levels of these nuclei, and also the in-band E2 transitions, are reasonably accounted for by the X(5) model. With simple assumptions on the nature of the octupole vibrations, it is also possible to describe the negative-parity sector with comparable accuracy without changing the description of the positive-parity part.

  13. The Low-Lying Electronic States of LiB

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    The spectroscopic constants for the triplet and singlet states of LiB below about 30 000/ cm are determined using an internally contracted multireference configuration interaction approach in conjunction with [6s 5p 3d 2f] atomic natural orbital basis sets. The ground state is (sup 3)Pi as found in previous work. No excited triplet states are found to be ideal for characterizing the ground state; the (1)(sup 3)Sigma(sup -) state has a transition energy that is too small for many experimental approaches and the (2)(sup 3)Pi and (3)(sup 3)Pi states have bond lengths that are significantly longer than the ground state, resulting in transition intensities that are spread out over many vibrational levels of the ground state.

  14. Low-lying electronic states of CuN calculated by MRCI method

    NASA Astrophysics Data System (ADS)

    Zhang, Shu-Dong; Liu, Chao

    2016-10-01

    The high accuracy ab initio calculation method of multi-reference configuration interaction (MRCI) is used to compute the low-lying eight electronic states of CuN. The potential energy curves (PECs) of the X3Σ-, 13Π, 23Σ-, 13Δ, 11Δ, 11Σ-, 11Π, and 5Σ- in a range of R = 0.1 nm-0.5 nm are obtained and they are goodly asymptotes to the Cu(2Sg) + N(4Su) and Cu(2Sg) + N(2Du) dissociation limits. All the possible vibrational levels, rotational constants, and spectral constants for the six bound states of X3Σ-, 13Π, 23Σ-, 11Δ, 11Σ-, and 11Π are obtained by solving the radial Schrödinger equation of nuclear motion with the Le Roy provided Level8.0 program. Also the transition dipole moments from the ground state X3Σ- to the excited states 13Π and 23Σ- are calculated and the result indicates that the 23Σ--X3Σ- transition has a much higher transition dipole moment than the 13Π-X3Σ- transition even though the 13Π state is much lower in energy than the 23Σ- state.

  15. An investigation into low-lying electronic states of HCS{sub 2} via threshold photoelectron imaging

    SciTech Connect

    Qin, Zhengbo; Cong, Ran; Liu, Zhiling; Xie, Hua; Tang, Zichao E-mail: fanhj@dicp.ac.cn; Fan, Hongjun E-mail: fanhj@dicp.ac.cn

    2014-06-07

    Low-energy photoelectron imaging spectra of HCS{sub 2}{sup −} are reported for the first time. Vibrationally resolved photodetachment transitions from the ground state of HCS{sub 2}{sup −} to the ground state and low-lying excited states of HCS{sub 2} are observed. Combined with the ab intio calculations and Franck-Condon simulations, well-resolved vibrational spectra demonstrate definitive evidence for the resolution of the ground-state and excited states of HCS{sub 2} radical in the gaseous phase. The ground state and two low-lying excited states of HCS{sub 2} radical are assigned as {sup 2}B{sub 2}, {sup 2}A{sub 2}, and {sup 2}A{sub 1} states, respectively. The adiabatic electron affinity is determined to be 2.910 ± 0.007 eV. And the term energies of the excited states, T{sub 0} = 0.451 ± 0.009 eV and 0.553 ± 0.009 eV, are directly measured from the experimental data, respectively. Angular filtering photoelectron spectra are carried out to assist in the spectral band assignment.

  16. Spectroscopy of the Low Lying States of CaO^{+}

    NASA Astrophysics Data System (ADS)

    VanGundy, Robert A.; Heaven, Michael

    2017-06-01

    Diatomic molecular ions that contain alkaline earth atoms are of interest for experiments involving ultra-cold molecular ions. The alkaline earth atomic cations are well suited for laser cooling as they have transitions that are analogous to those of the alkali metals. Hence, Coulomb crystals are readily formed in rf traps. Reactions of these atomic ions yield diatomic products that are sympathetically cooled to low translational temperatures by the surrounding atomic ions. In principle, spectroscopic measurements may be used to probe the internal energies of the molecular ions. However, gas phase spectroscopic data for the ions of interest are lacking. In the present study we have investigated CaO^{+} using pulsed field ionization-zero kinetic energy photoelectron spectroscopy (PFI-ZEKE). Molecular constants for low energy vibrational levels for the ground state (^{2}Π_{3/2}) and two electronic states (^{2}Π_{1/2} and ^{2}Σ^{+}) have been determined. These measurements also provide the first accurate value for the ionization energy of CaO. Comparisons with high-level theoretical calculations will be discussed.

  17. A theoretical study of low-lying electronic states of aminonitrene, phosphinonitrene, and phosphinocarbene

    NASA Astrophysics Data System (ADS)

    Hoffmann, Mark R.; Kuhler, Kathleen

    1991-06-01

    The recently formulated multiconfiguration-based unitary coupled electron pair approximation (UCEPA) is compared with multireference configuration interaction (MR-CISD) calculations, including all single and double excitations, for the molecules in this study. The electronic states of the molecules in this study are not only of experimental interest, but represent a challenge to any formalism to accurately predict the energy separations of the low-lying electronic states. The equilibrium geometries and fundamental vibrational frequencies of the three lowest electronic states (i.e., 1A1, 3A`, and 1A`) of aminonitrene H2N2, and phosphinonitrene, H2PN, have been determined using a split-valence basis with polarization functions on the heavy atoms and a small complete active space self-consistent-field (CASSCF) description of the active space. Both MR-CISD and UCEPA calculations have been performed at the equilibrium structures using larger basis sets to accurately determine the relative energetics of the electronic states. The equilibrium geometries and vibrational frequencies of the two lowest electronic states (i.e., 1A' and 3A`) of phosphinocarbene, H2PCH, have been determined using a larger than double zeta basis set, augmented with polarization and diffuse functions, and a CASSCF description of the active space. Both MR-CISD and UCEPA calculations were performed on the equilibrium structures and predict that the singlet lies between 10.4 and 11.8 kcal/mol lower in energy than the triplet. The use of a generalized valence bond (GVB) reference function within UCEPA is introduced and is shown to be a useful approximation.

  18. Low lying electric dipole excitations in nuclei of the rare earth region

    SciTech Connect

    von Brentano, P.; Zilges, A.; Herzberg, R.D.; Zamfir, N.V.; Kneissl, U.; Heil, R.D.; Pitz, H.H.; Wesselborg, C.

    1992-10-01

    From many experiments with low energy photon scattering on deformed rare earth nuclei we have obtained detailed information about the distribution of electric dipole strength below 4 MeV. Apart from some weaker transitions between 2 and 4 MeV we observed one, and sometimes two, very strong El-groundstate transitions around 1.5 MeV in all examined nuclei. They arise from the de-excitation of the bandheads of the (J{sup {pi}},K)=(l{sup {minus}},0) and (J{sup {pi}},K)=(l{sup {minus}},1) octupole vibrational bands. It is shown that the decay branching ratios and the absolute transition strengths of these states can be reproduced rather well with an improved T(El)-operator in the sdf-Interacting Boson Model. Another class of octupole states has been investigated in the region of the semimagic nucleus {sup 142}Nd. Here a quintuplet of collective excitations around 3.5 MeV is expected due to the coupling of the 3{minus}-octupole vibration with the 2+-quadrupole vibration. We performed photon scattering experiments on the odd A neighboring nucleus {sup 141}Pr and found first evidence for the existence of 3{sup {minus}}{circle_times}2+{circle_times}particle-states.

  19. The Low-Lying Electronic States of Scandium Monocarbide, ScC

    NASA Astrophysics Data System (ADS)

    Chen, Chiao-Wei; Merer, Anthony; Hsu, Yen-Chu

    2017-06-01

    Extensive wavelength-resolved fluorescence studies have been carried out for the electronic bands of ScC and Sc{}^{13}C lying in the range 14000 - 16000 cm^{-1}. Taken together with detailed rotational analyses of these bands, these studies have clarified the natures of the low-lying electronic states. The ground state is an Ω = 3/2 state, with a vibrational frequency of 648 cm^{-1}, and the first excited electronic state is an Ω = 5/2 state, with a frequency of 712 cm^{-1}, lying 155.54 cm^{-1} higher. These states are assigned as the lowest spin-orbit components of X^2Π_i and a^4Π_i, respectively. The quartet nature of the a state is confirmed by the observation of the ^4Π_{3/2} component, 18.71 cm^{-1} above the ^4Π_{5/2} component. The strongest bands in the region studied are two ^4Δ_{7/2} - ^4Π_{5/2} transitions, where the upper states lie 14355 and 15445 cm^{-1} above X^2Π_{3/2}. Extensive doublet-quartet mixing occurs, which results in some complicated emission patterns. The energy order, a^4Π above X^2Π, is consistent with the ab initio calculations of Kalemos et al., but differs from that found by Simard et al in the isoelectronic YC molecule. A. Kalemos, A. Mavridis and J.F. Harrison, J. Phys. Chem. A155, 755 (2001). B. Simard, P.A. Hackett and W.J. Balfour, Chem. Phys. Lett., 230, 103 (1994).

  20. Vibration study of the APS storage ring 0.8 meter quadrupole magnet/magnet support assembly

    SciTech Connect

    Jendrzejczyk, J.A.; Wambsganss, M.W.; Smith, R.K.

    1991-06-01

    The objectives of this study are as follows: Determine the vibration characteristics (frequency, damping, and mode shapes) of the magnet on prototypic supports (the actual mounting system used to mount the magnet on the girder). Measure system response to ambient floor motion. Measure the effect of various modifications to determine if the magnet response can be modified to minimize unwanted response characteristics. Modifications investigated include support schemes, increasing system damping, and increasing mechanical rigidity. Measure system response to coolant flow. Determine vibrational characteristics of a large concrete block placed on a concrete floor, including response to ambient floor motions.

  1. Energies and Electric Dipole Transitions for Low-Lying Levels of Protactinium IV and Uranium V

    NASA Astrophysics Data System (ADS)

    Ürer, Güldem; Özdemir, Leyla

    2012-02-01

    We have reported a relativistic multiconfiguration Dirac-Fock (MCDF) study on low-lying level structures of protactinium IV (Z =91) and uranium V (Z =92) ions. Excitation energies and electric dipole (E1) transition parameters (wavelengths, oscillator strengths, and transition rates) for these low-lying levels have been given. We have also investigated the influence of the transverse Breit and quantum electrodynamic (QED) contributions besides correlation effects on the level structure. A comparison has been made with a few available data for these ions in the literature.

  2. Ab initio MRCI+Q study on low-lying states of CS including spin-orbit coupling.

    PubMed

    Li, Rui; Wei, Changli; Sun, Qixiang; Sun, Erping; Xu, Haifeng; Yan, Bing

    2013-03-21

    Carbon monosulfide (CS), which plays an important role in a variety of research fields, has long received considerable interest. Due to its transient nature and large state density, the electronic states of CS have not been well understood, especially the interactions between different states. In this paper, we performed a detail ab initio study on the low-lying electronic states of CS by means of the internally contracted multireference configuration interaction method (including Davidson correction) with scalar relativistic correction using the Douglas-Kroll-Hess Hamiltonian. We focused on the spin-orbit coupling of the states via the state interaction method with the full Breit-Pauli Hamiltonian. The potential energy curves (PECs) of 18 Λ-S states correlated with the lowest dissociation limit of the CS molecule were calculated, as well as those of 50 Ω states generated from the Λ-S states. The spectroscopic constants of the bound states were obtained, which are in good agreement with previous available experimental and theoretical results. The state perturbations of the a(3)Π and A(1)Π states with other low-lying electronic states are discussed in detail, based on the calculated spin-orbit matrix as well as the PECs of the Ω states. Avoided crossing in the states of CS was indicated when spin-orbit coupling was taken into account. Finally, the allowed transition dipole moments as well as the lifetimes of the five lowest vibrational states of the A(1)Π1, A'(1)Σ(+)0(+) and a(3)Πi states were obtained.

  3. Ab initio study on the ground and low-lying excited states of cesium iodide (CsI).

    PubMed

    Kurosaki, Yuzuru; Matsuoka, Leo; Yokoyama, Keiichi; Yokoyama, Atsushi

    2008-01-14

    Potential energy curves (PECs) for the ground and low-lying excited states of the cesium iodide (CsI) molecule have been calculated using the internally contracted multireference configuration interaction calculation with single and double excitation method with the relativistic pseudopotentials. PECs for seven Lambda-S states, X 1Sigma+, 2 1Sigma+, 3Sigma+, 1Pi, and 3Pi are first calculated and then those for 13 Omega states are obtained by diagonalizing the matrix of the electronic Hamiltonian H(el) plus the effective one-electron spin-orbit (SO) Hamiltonian H(SO). Spectroscopic constants for the calculated ground X 0+-state PEC with the Davidson correction are found to agree well with the experiment. Transition dipole moments (TDMs) between X 0 and the other Omega states are also obtained and the TDM between X 0+ and A 0+ is predicted to be the largest and that between X 0+ and B 0+ is the second largest around the equilibrium internuclear distance. The TDMs between X 0+ and the Omega=1 states are estimated to be nonzero, but they are notably small as compared with those between the 0+ states. Finally, vibrational levels of the X 0+ PEC for the two isotopic analogs, (133)CsI and (135)CsI, are numerically obtained to investigate the isotope effect on the vibrational-level shift. It has been found that the maximized available isotope shift is approximately 30 cm(-1) around nu=136.

  4. Jet-cooled laser-induced dispersed fluorescence spectroscopy of NiC: Observation of low-lying Ω = 0+ state

    NASA Astrophysics Data System (ADS)

    Mukund, Sheo; Yarlagadda, Suresh; Bhattacharyya, Soumen; Nakhate, S. G.

    2014-01-01

    Laser-induced dispersed fluorescence spectra of 58Ni12C molecules, produced in a free-jet apparatus, have been studied. A new low-lying Ω = 0+ state has been observed at Te = 5178 (6) cm-1. Based on previous ab initio calculations this state is plausibly assigned as 0+ spin-orbit component of the first excited 3 Π state. The term energies of vibrational levels up to v = 10 for X1Σ+ ground and v = 3 for Ω = 0+ states have been determined. The harmonic and anharmonic wavenumbers respectively equal to 833 (4) and 6.7 (13) cm-1 for Ω = 0+ state have been measured.

  5. New extrapolation method for low-lying states of nuclei in the sd and the pf shells

    SciTech Connect

    Shen, J. J.; Zhao, Y. M.; Arima, A.; Yoshinaga, N.

    2011-04-15

    We study extrapolation approaches to evaluate energies of low-lying states for nuclei in the sd and pf shells, by sorting the diagonal matrix elements of the nuclear shell-model Hamiltonian. We introduce an extrapolation method with perturbation and apply our new method to predict both low-lying state energies and E2 transition rates between low-lying states. Our predicted results arrive at an accuracy of the root-mean-squared deviations {approx}40-60 keV for low-lying states of these nuclei.

  6. Radiative proton capture to low-lying T =0 and T =1 states in 10B

    NASA Astrophysics Data System (ADS)

    Chakrabarty, D. R.; Datar, V. M.; Kumar, Suresh; Mirgule, E. T.; Mishra, G.; Rout, P. C.; Ghosh, C.; Nanal, V.; Joshi, S.; Kujur, R.

    2017-01-01

    Cross sections of the radiative proton capture reaction 9Be(p ,γ ) , leading to the low-lying excited states in 10B with isospin T =0 and 1, have been measured over the proton energy range of 7 to 20 MeV. For this, the method of coincidence between the primary and the secondary γ rays has been used. These γ rays are emitted following, respectively, the proton capture to an excited state and the subsequent decay of that state. A direct-semidirect capture model calculation has been performed and compared with the experimental data. The experimental results do not show a strong isospin dependence of the GDR strength function built on the low-lying states. The derived photoproton cross sections on these states and the earlier-measured photoneutron cross sections on the ground state of 10B show a large difference.

  7. Low-lying structure and shape evolution in neutron-rich Se isotopes

    NASA Astrophysics Data System (ADS)

    Chen, S.; Doornenbal, P.; Obertelli, A.; Rodríguez, T. R.; Authelet, G.; Baba, H.; Calvet, D.; Château, F.; Corsi, A.; Delbart, A.; Gheller, J.-M.; Giganon, A.; Gillibert, A.; Lapoux, V.; Motobayashi, T.; Niikura, M.; Paul, N.; Roussé, J.-Y.; Sakurai, H.; Santamaria, C.; Steppenbeck, D.; Taniuchi, R.; Uesaka, T.; Ando, T.; Arici, T.; Blazhev, A.; Browne, F.; Bruce, A. M.; Caroll, R.; Chung, L. X.; Cortés, M. L.; Dewald, M.; Ding, B.; Flavigny, F.; Franchoo, S.; Górska, M.; Gottardo, A.; Jungclaus, A.; Lee, J.; Lettmann, M.; Linh, B. D.; Liu, J.; Liu, Z.; Lizarazo, C.; Momiyama, S.; Moschner, K.; Nagamine, S.; Nakatsuka, N.; Nita, C. R.; Nobs, C.; Olivier, L.; Orlandi, R.; Patel, Z.; Podolyak, Zs.; Rudigier, M.; Saito, T.; Shand, C.; Söderström, P.-A.; Stefan, I.; Vaquero, V.; Werner, V.; Wimmer, K.; Xu, Z.

    2017-04-01

    Neutron-rich 88,90,92,94Se isotopes were studied via in-beam γ -ray spectroscopy after nucleon removal reactions at intermediate energies at the Radioactive Isotope Beam Factory. Based on γ -γ coincidence analysis, low-lying excitation level schemes are proposed for these nuclei, including the 21+, 41+ states and 22+ states at remarkably low energies. The low-lying 22+ states, along with other features, indicate triaxiality in these nuclei. The experimental results are in good overall agreement with self-consistent beyond-mean-field calculations based on the Gogny D1S interaction, which suggests both triaxial degree of freedom and shape coexistence playing important roles in the description of intrinsic deformations in neutron-rich Se isotopes.

  8. Involvement of a low-lying Rydberg state in the ultrafast relaxation dynamics of ethylene

    SciTech Connect

    Champenois, Elio G.; Shivaram, Niranjan H.; Belkacem, Ali; Wright, Travis W.; Yang, Chan-Shan; Cryan, James P.

    2016-01-07

    We present a measurement of the time-resolved photoelectron kinetic energy spectrum of ethylene using 156 nm and 260 nm laser pulses. The 156 nm pulse first excites ethylene to the {sup 1}B{sub 1u} (ππ{sup ∗}) electronic state where 260 nm light photoionizes the system to probe the relaxation dynamics with sub-30 fs resolution. Recent ab initio calculations by Mori et al. [J. Phys. Chem. A 116, 2808-2818 (2012)] have predicted an ultrafast population transfer from the initially excited state to a low-lying Rydberg state during the relaxation of photoexcited ethylene. The measured photoelectron kinetic energy spectrum reveals wave packet motion on the valence state and shows indications that the low-lying π3s Rydberg state is indeed transiently populated via internal conversion following excitation to the ππ{sup ∗} state, supporting the theoretical predictions.

  9. Calculations of energy levels and lifetimes of low-lying states of barium and radium

    SciTech Connect

    Dzuba, V. A.; Ginges, J. S. M.

    2006-03-15

    We use the configuration-interaction method and many-body perturbation theory to perform accurate calculations of energy levels, transition amplitudes, and lifetimes of low-lying states of barium and radium. Calculations for radium are needed for the planning of measurements of parity- and time-invariance-violating effects which are strongly enhanced in this atom. Calculations for barium are used to control the accuracy of the calculations.

  10. A theoretical study of the low-lying states of Ti2 and Zr2

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.; Rosi, Marzio

    1991-01-01

    The low-lying states of Ti2 and the valence isoelectronic Zr2 are examined theoretically by means of a multireference configuration-interaction (MRCI) method. MRCI calculations demonstrate that two of the Zr2 states are very low-lying and that the resulting vertical excitation is consistent with the optical spectrum of Zr2. The ground state is predicted for Ti2 on the basis of valence correlation with the MRCI method and the average coupled-pair functional technique. Calculations of the inner-shell correlation effects are estimated and found to lower the 3Delta g state to a ground state, and another to a very low-lying state. The ground state of Ti2 is assigned to 3Delta g since it is lower than the other state at all levels of correlation and is derived from the same atomic asymptote. This conclusion is supported by the lack of an electron-spin resonance signal but contradicts the absence of subcomponents on the Raman spectral lines.

  11. Spectroscopic properties and potential energy curves of low-lying electronic states of RuC.

    PubMed

    Guo, Rui; Balasubramanian, K

    2004-04-22

    The RuC molecule has been a challenging species due to the open-shell nature of Ru resulting in a large number of low-lying electronic states. We have carried out state-of-the-art calculations using the complete active space multiconfiguration self-consistent field followed by multireference configuration interaction methods that included up to 18 million configurations, in conjunction with relativistic effects. We have computed 29 low-lying electronic states of RuC with different spin multiplicities and spatial symmetries with energy separations less than 38,000 cm(-1). We find two very closely low-lying electronic states for RuC, viz., 1Sigma+ and 3Delta with the 1Sigma+ being stabilized at higher levels of theory. Our computed spectroscopic constants and dipole moments are in good agreement with experiment although we have reported more electronic states than those that have been observed experimentally. Our computations reveal a strongly bound 1Sigma+ state with a large dipole moment which is most likely the experimentally observed ground state and an energetically close 3Delta state with a smaller dipole moment. Overall our computed spectroscopic constants of the excited states with energy separations less than 18,000 cm(-1) agree quite well with those of the corresponding observed states.

  12. Spectroscopic Properties and Potential Energy Curves of Low-lying electronic States of RuC

    SciTech Connect

    Balasubramanian, K; Guo, R

    2003-12-22

    The RuC molecule has been a challenging species due to the open-shell nature of Ru resulting in a large number of low-lying electronic states. We have carried out state-of-the-art calculations using the complete active space multi-configuration self-consistent field (CASSCF) followed by multireference configuration interaction (MRCI) methods that included up 18 million configurations, in conjunction with relativistic effects. We have computed 29 low-lying electronic states of RuC with different spin multiplicities and spatial symmetries with energy separations less than 38 000 cm{sup -1}. We find two very closely low-lying electronic states for RuC, viz., {sup 1}{Sigma}{sup +} and {sup 3}{Delta} with the {sup 1}{Sigma}{sup +} being stabilized at higher levels of theory. Our computed spectroscopic constants and dipole moments are in good agreement with experiment although we have reported more electronic states than those that have been observed experimentally. Our computations reveal a strongly bound X{sup 1}{Sigma}{sup +} state with a large dipole moment and an energetically close {sup 3}{Delta} state with a smaller dipole moment. Overall our computed spectroscopic constants of the excited states with energy separations less than 18000 cm{sup -1} agree quite well with those of the corresponding observed states.

  13. Symptomatic lumbar disc protrusion causing progressive myelopathy in a low-lying cord.

    PubMed

    Srinivas, Shreya; Shetty, Rohit; Collins, Iona

    2012-06-01

    Low-lying cord is an uncommon entity, and cord compression due lumbar disc disease is rarely encountered. We discuss our experience with a case of lumbar cord compression secondary to a large disc protrusion, which caused myelopathy in a low-lying/tethered cord. A 77-year-old woman with known spina bifida occulta presented with 6-week history of severe low back pain and progressive paraparesis. Magnetic resonance imaging showed a low-lying tethered cord and a large disc prolapse at L2/3 causing cord compression with associated syringomyelia. Medical comorbidities precluded her from anterior decompression, and therefore a posterior decompression was performed. She recovered full motor power in her lower limbs and could eventually walk unaided. She had a deep wound infection, which was successfully treated with debridement, negative pressure therapy (vacuum-assisted closure pump), and antibiotics. Six months after surgery, her Oswestry Disability Index improved from 55% preoperatively to 20%. Posterior spinal cord decompression for this condition has been successful in our case, and we believe that the lumbar lordosis may have helped indirectly decompress the spinal cord by posterior decompression alone.

  14. Low-lying Photoexcited States of a One-Dimensional Ionic Extended Hubbard Model

    NASA Astrophysics Data System (ADS)

    Yokoi, Kota; Maeshima, Nobuya; Hino, Ken-ichi

    2017-10-01

    We investigate the properties of low-lying photoexcited states of a one-dimensional (1D) ionic extended Hubbard model at half-filling. Numerical analysis by using the full and Lanczos diagonalization methods shows that, in the ionic phase, there exist low-lying photoexcited states below the charge transfer gap. As a result of comparison with numerical data for the 1D antiferromagnetic (AF) Heisenberg model, it was found that, for a small alternating potential Δ, these low-lying photoexcited states are spin excitations, which is consistent with a previous analytical study [Katsura et al., Phys. Rev. Lett. 103, 177402 (2009)]. As Δ increases, the spectral intensity of the 1D ionic extended Hubbard model rapidly deviates from that of the 1D AF Heisenberg model and it is clarified that this deviation is due to the neutral-ionic domain wall, an elementary excitation near the neutral-ionic transition point.

  15. Low-lying dipole resonance in neutron-rich Ne isotopes

    NASA Astrophysics Data System (ADS)

    Yoshida, Kenichi; van Giai, Nguyen

    2008-07-01

    Microscopic structure of the low-lying isovector dipole excitation mode in neutron-rich Ne26,28,30 is investigated by performing deformed quasiparticle-random-phase-approximation (QRPA) calculations. The particle-hole residual interaction is derived from a Skyrme force through a Landau-Migdal approximation. We obtain the low-lying resonance in Ne26 at around 8.6 MeV. It is found that the isovector dipole strength at Ex<10 MeV exhausts about 6.0% of the classical Thomas-Reiche-Kuhn dipole sum rule. This excitation mode is composed of several QRPA eigenmodes, one is generated by a ν(2s1/2-12p3/2) transition dominantly and the other mostly by a ν(2s1/2-12p1/2) transition. The neutron excitations take place outside of the nuclear surface reflecting the spatially extended structure of the 2s1/2 wave function. In Ne30, the deformation splitting of the giant resonance is large, and the low-lying resonance overlaps with the giant resonance.

  16. STS-31 Discovery, OV-103, rockets through low-lying clouds after KSC liftoff

    NASA Technical Reports Server (NTRS)

    1990-01-01

    STS-31 Discovery, Orbiter Vehicle (OV) 103, rides above the firey glow of the solid rocket boosters (SRBs) and space shuttle main engines (SSMEs) and a long trail of exhaust as it heads toward Earth orbit. Kennedy Space Center (KSC) Launch Complex (LC) Pad 39B is covered in an exhaust cloud moments after the liftoff of OV-103 at 8:33:51.0492 am (Eastern Daylight Time (EDT)). The exhaust plume pierces the low-lying clouds as OV-103 soars into the clear skies above. A nearby waterway appears in the foreground.

  17. STS-31 Discovery, OV-103, is hidden in low-lying clouds after KSC liftoff

    NASA Technical Reports Server (NTRS)

    1990-01-01

    STS-31 Discovery, Orbiter Vehicle (OV) 103, is hidden in low-lying cloud cover as it rises above Kennedy Space Center (KSC) Launch Complex (LC) Pad 39B just after its liftoff at 8:33:51.0492 am (Eastern Daylight Time (EDT)). The glow of the solid rocket booster (SRB) and the space shuttle main engine (SSME) firings appears just below the cloud cover and is reflected in the nearby waterway (foreground). An exhaust plume trails from OV-103 and its SRBs and covers the launch pad area.

  18. A numerical study of the thermal stability of low-lying coronal loops

    NASA Technical Reports Server (NTRS)

    Klimchuk, J. A.; Antiochos, S. K.; Mariska, J. T.

    1986-01-01

    The nonlinear evolution of loops that are subjected to a variety of small but finite perturbations was studied. Only the low-lying loops are considered. The analysis was performed numerically using a one-dimensional hydrodynamical model developed at the Naval Research Laboratory. The computer codes solve the time-dependent equations for mass, momentum, and energy transport. The primary interest is the active region filaments, hence a geometry appropriate to those structures was considered. The static solutions were subjected to a moderate sized perturbation and allowed to evolve. The results suggest that both hot and cool loops of the geometry considered are thermally stable against amplitude perturbations of all kinds.

  19. Computed potential surfaces for six low-lying states of Ni3

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.

    1987-01-01

    Selected portions of the potential surfaces for six low lying states of Ni3 are the subject of the present SCF/CCI calculations using the effective core potentials developed by Hay and Wadt (1985); the four states are studied for near-equilateral triangle geometries are within 0.04 eV of each other. Two states are studied for linear geometries, of which the first is 0.16 eV higher than the corresponding near-equilateral triangle state and the second is estimated to be nearly degenerate with the near-equilateral triangle structures.

  20. A New Approach to Solve the Low-lying States of the Schroedinger Equation

    NASA Astrophysics Data System (ADS)

    Lee, T. D.

    2005-12-01

    We review a new iterative procedure to solve the low-lying states of the Schroedinger equation, done in collaboration with Richard Friedberg. For the groundstate energy, the nth order iterative energy is bounded by a finite limit, independent of n; thereby it avoids some of the inherent difficulties faced by the usual perturbative series expansions. For a fairly large class of problems, this new procedure can be proved to give convergent iterative solutions. These convergent solutions include the long standing difficult problem of a quartic potential with either symmetric or asymmetric minima

  1. New blue emissive conjugated small molecules with low lying HOMO energy levels for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Trupthi Devaiah, C.; Hemavathi, B.; Ahipa, T. N.

    2017-03-01

    Versatile conjugated small molecules bearing cyanopyridone core (CP1-5), composed of various donor/acceptor moieties at position - 4 and - 6 have been designed, developed and characterized. Their solvatochromic studies were conducted and analyzed using Lippert-Mataga, Kamlet-Taft and Catalan solvent scales and interesting results were obtained. The polarizability/dipolarity of the solvent greatly influenced the spectra. The electrochemical studies were carried out using cyclic voltammetry to calculate the HOMO-LUMO energy levels. The study revealed that the synthesized conjugated small molecules possess low lying HOMO energy levels which can be exploited for application in various fields of optoelectronics.

  2. {sup 10}Li low-lying resonances populated by one-neutron transfer

    SciTech Connect

    Cavallaro, M. Agodi, C.; Carbone, D.; Cunsolo, A.; De Napoli, M.; Cappuzzello, F.; Bondì, M.; Davids, B.; Galinski, N.; Ruiz, C.; Davinson, T.; Sanetullaev, A.; Foti, A.; Kanungo, R.; Lenske, H.; Orrigo, S. E. A.

    2015-10-15

    The {sup 9}Li + {sup 2}H → {sup 10}Li + {sup 1}H one-neutron transfer reaction has been performed at 100 MeV incident energy at TRIUMF using a {sup 9}Li beam delivered by the ISAC-II facility. A setup based on double-sided silicon strip detectors has been used in order to detect and identify the outgoing {sup 9}Li produced by the {sup 10}Li breakup at forward angles and the recoil protons emitted at backward angles. The {sup 10}Li low-lying resonances, whose energies, widths and configurations are still unclear, have been populated with significant statistics.

  3. Microscopic study of low-lying collective bands in 77 Kr

    NASA Astrophysics Data System (ADS)

    Tripathy, K. C.; Sahu, R.; Mishra, S.

    2006-02-01

    The structure of the collective bands in ^{77}Kr is investigated within our deformed shell model (DSM) based on Hartree-Fock states. The different levels are classified into collective bands on the basis of their B(E2) values. The calculated K= 5/2^+ ground band agrees reasonably well with the experiment. An attempt has been made to study the structure of the 3-quasiparticle band based on large J state in this nucleus. The calculated collective bands, the B(E2), and B(M1) values are compared with available experimental data. The nature of alignments in the low-lying bands is also analyzed.

  4. Low-Lying Structure of 50Ar and the N =32 Subshell Closure

    NASA Astrophysics Data System (ADS)

    Steppenbeck, D.; Takeuchi, S.; Aoi, N.; Doornenbal, P.; Matsushita, M.; Wang, H.; Utsuno, Y.; Baba, H.; Go, S.; Lee, J.; Matsui, K.; Michimasa, S.; Motobayashi, T.; Nishimura, D.; Otsuka, T.; Sakurai, H.; Shiga, Y.; Shimizu, N.; Söderström, P.-A.; Sumikama, T.; Taniuchi, R.; Valiente-Dobón, J. J.; Yoneda, K.

    2015-06-01

    The low-lying structure of the neutron-rich nucleus 50Ar has been investigated at the Radioactive Isotope Beam Factory using in-beam γ -ray spectroscopy with 9Be (54Ca, 50Ar +γ )X , 9Be (55Sc, 50Ar +γ )X , and 9Be (56Ti, 50Ar +γ )X multinucleon removal reactions at ˜220 MeV /u . A γ -ray peak at 1178(18) keV is reported and assigned as the transition from the first 2+ state to the 0+ ground state. A weaker, tentative line at 1582(38) keV is suggested as the 41+→21+ transition. The experimental results are compared to large-scale shell-model calculations performed in the s d p f model space using the SDPF-MU effective interaction with modifications based on recent experimental data for exotic calcium and potassium isotopes. The modified Hamiltonian provides a satisfactory description of the new experimental results for 50Ar and, more generally, reproduces the energy systematics of low-lying states in neutron-rich Ar isotopes rather well. The shell-model calculations indicate that the N =32 subshell gap in 50Ar is similar in magnitude to those in 52Ca and 54Ti and, notably, predict an N =34 subshell closure in 52Ar that is larger than the one recently reported in 54Ca.

  5. Low-lying {Lambda} baryons with spin 1/2 in two-flavor lattice QCD

    SciTech Connect

    Takahashi, Toru T.; Oka, Makoto

    2010-02-01

    Low-lying {Lambda} baryons with spin 1/2 are analyzed in full (unquenched) lattice QCD. We construct 2x2 cross correlators from flavor SU(3) octet and singlet baryon operators, and diagonalize them so as to extract information of two low-lying states for each parity. The two-flavor CP-PACS gauge configurations are used, which are generated in the renormalization-group improved gauge action and the O(a)-improved quark action. Three different {beta}'s, {beta}=1.80, 1.95, and 2.10, are employed, whose corresponding lattice spacings are a=0.2150, 0.1555, and 0.1076 fm. For each cutoff, we use four hopping parameters, ({kappa}{sub val},{kappa}{sub sea}), which correspond to the pion masses ranging about from 500 MeV to 1.1 GeV. Results indicate that there are two negative-parity {Lambda} states nearly degenerate at around 1.6 GeV, while no state as low as {Lambda}(1405) is observed. By decomposing the flavor components of each state, we find that the lowest (1st-excited) negative-parity state is dominated by flavor-singlet (flavor-octet) component. We also discuss meson-baryon components of each state, which has drawn considerable attention in the context of multiquark pictures of {Lambda}(1405).

  6. Theoretical study of the electrostatic and steric effects on the spectroscopic characteristics of the metal-ligand unit of heme proteins. 2. C-O vibrational frequencies, 17O isotropic chemical shifts, and nuclear quadrupole coupling constants.

    PubMed

    Kushkuley, B; Stavrov, S S

    1997-02-01

    The quantum chemical calculations, vibronic theory of activation, and London-Pople approach are used to study the dependence of the C-O vibrational frequency, 17O isotropic chemical shift, and nuclear quadrupole coupling constant on the distortion of the porphyrin ring and geometry of the CO coordination, changes in the iron-carbon and iron-imidazole distances, magnitude of the iron displacement out of the porphyrin plane, and presence of the charged groups in the heme environment. It is shown that only the electrostatic interactions can cause the variation of all these parameters experimentally observed in different heme proteins, and the heme distortions could modulate this variation. The correlations between the theoretically calculated parameters are shown to be close to the experimentally observed ones. The study of the effect of the electric field of the distal histidine shows that the presence of the four C-O vibrational bands in the infrared absorption spectra of the carbon monoxide complexes of different myoglobins and hemoglobins can be caused by the different orientations of the different tautomeric forms of the distal histidine. The dependence of the 17O isotropic chemical shift and nuclear quadrupole coupling constant on pH and the distal histidine substitution can be also explained from the same point of view.

  7. Theoretical Study of the Electrostatic and Steric Effects on the Spectroscopic Characteristics of the Metal-Ligand Unit of Heme Proteins. 2. C-O Vibrational Frequencies, 17O Isotropic Chemical Shifts, and Nuclear Quadrupole Coupling Constants

    PubMed Central

    Kushkuley, Boris; Stavrov, Solomon S.

    1997-01-01

    The quantum chemical calculations, vibronic theory of activation, and London-Pople approach are used to study the dependence of the C-O vibrational frequency, 17O isotropic chemical shift, and nuclear quadrupole coupling constant on the distortion of the porphyrin ring and geometry of the CO coordination, changes in the iron-carbon and iron-imidazole distances, magnitude of the iron displacement out of the porphyrin plane, and presence of the charged groups in the heme environment. It is shown that only the electrostatic interactions can cause the variation of all these parameters experimentally observed in different heme proteins, and the heme distortions could modulate this variation. The correlations between the theoretically calculated parameters are shown to be close to the experimentally observed ones. The study of the effect of the electric field of the distal histidine shows that the presence of the four C-O vibrational bands in the infrared absorption spectra of the carbon monoxide complexes of different myoglobins and hemoglobins can be caused by the different orientations of the different tautomeric forms of the distal histidine. The dependence of the 17O isotropic chemical shift and nuclear quadrupole coupling constant on pH and the distal histidine substitution can be also explained from the same point of view. PMID:9017215

  8. Is Preoperative Chemoradiotherapy Beneficial for Sphincter Preservation in Low-Lying Rectal Cancer Patients?

    PubMed Central

    Park, In Ja; Yu, Chang Sik; Lim, Seok-Byung; Lee, Jong Lyul; Kim, Chan Wook; Yoon, Yong Sik; Park, Seong Ho; Kim, Jin Cheon

    2016-01-01

    Abstract The present study explored the benefit of preoperative chemoradiotherapy (PCRT) for sphincter preservation in locally advanced low-lying rectal cancer patients who underwent stapled anastomosis, especially in those with deep and narrow pelvises determined by magnetic resonance imaging. Patients with locally advanced low-lying rectal cancer (≤5 cm from the anal verge) who underwent stapled anastomosis were included. Patients were categorized into two groups (PCRT+ vs. PCRT–) according to PCRT application. Patients in the PCRT+ group were matched to those in the PCRT– group according to potential confounding factors (age, gender, clinical stage, and body mass index) for sphincter preservation. Sphincter preservation, permanent stoma, and anastomosis-related complications were compared between the groups. Pelvic magnetic resonance imaging was used to measure 12 dimensions representing pelvic cavity depth and width with which deep and narrow pelvis was defined. The impact of PCRT on sphincter preservation and permanent stoma in pelvic dimensions defined as deep and narrow pelvis was evaluated, and factors associated with sphincter preservation and permanent stoma were analyzed. One hundred sixty-six patients were one-to-one matched between the PCRT+ and PCRT− groups. Overall, sphincter-saving surgery was performed in 66.3% and the rates were not different between the 2 groups. Anastomotic complications and permanent stoma occurred nonsignificantly more frequently in the PCRT+ group. PCRT was not associated with higher rate of sphincter preservation in all pelvic dimensions defined as deep and narrow pelvis, while PCRT was related to higher rate of permanent stoma in shorter transverse diameter and interspinous distance. On logistic regression analysis, PCRT was not shown to influence both sphincter preservation and permanent stoma, while longer transverse diameter and interspinous distance were associated with lower rate of permanent stoma. PCRT had

  9. Is Preoperative Chemoradiotherapy Beneficial for Sphincter Preservation in Low-Lying Rectal Cancer Patients?

    PubMed

    Park, In Ja; Yu, Chang Sik; Lim, Seok-Byung; Lee, Jong Lyul; Kim, Chan Wook; Yoon, Yong Sik; Park, Seong Ho; Kim, Jin Cheon

    2016-05-01

    The present study explored the benefit of preoperative chemoradiotherapy (PCRT) for sphincter preservation in locally advanced low-lying rectal cancer patients who underwent stapled anastomosis, especially in those with deep and narrow pelvises determined by magnetic resonance imaging.Patients with locally advanced low-lying rectal cancer (≤5 cm from the anal verge) who underwent stapled anastomosis were included. Patients were categorized into two groups (PCRT+ vs. PCRT-) according to PCRT application. Patients in the PCRT+ group were matched to those in the PCRT- group according to potential confounding factors (age, gender, clinical stage, and body mass index) for sphincter preservation. Sphincter preservation, permanent stoma, and anastomosis-related complications were compared between the groups. Pelvic magnetic resonance imaging was used to measure 12 dimensions representing pelvic cavity depth and width with which deep and narrow pelvis was defined. The impact of PCRT on sphincter preservation and permanent stoma in pelvic dimensions defined as deep and narrow pelvis was evaluated, and factors associated with sphincter preservation and permanent stoma were analyzed.One hundred sixty-six patients were one-to-one matched between the PCRT+ and PCRT- groups. Overall, sphincter-saving surgery was performed in 66.3% and the rates were not different between the 2 groups. Anastomotic complications and permanent stoma occurred nonsignificantly more frequently in the PCRT+ group. PCRT was not associated with higher rate of sphincter preservation in all pelvic dimensions defined as deep and narrow pelvis, while PCRT was related to higher rate of permanent stoma in shorter transverse diameter and interspinous distance. On logistic regression analysis, PCRT was not shown to influence both sphincter preservation and permanent stoma, while longer transverse diameter and interspinous distance were associated with lower rate of permanent stoma.PCRT had no beneficial

  10. Ab initio MRSDCI study on the low-lying electronic states of the lithium chloride molecule (LiCl)

    NASA Astrophysics Data System (ADS)

    Kurosaki, Yuzuru; Yokoyama, Keiichi

    2012-08-01

    Potential energy curves (PECs) for the low-lying states of the lithium chloride molecule (LiCl) have been calculated using the internally contracted multireference single- and double-excitation configuration interaction (MRSDCI) method with the aug-cc-PVnZ (AVnZ) and aug-cc-PCVnZ (ACVnZ) basis sets, where n = T, Q, and 5. First, we calculate PECs for 7 spin-orbit (SO)-free Λ-S states, X1Σ+, A1Σ+, 3Σ+, 1Π, and 3Π, and then obtain PECs for 13 SO Ω states, X0+, A0+, B0+, 0-(I), 0-(II), 1(I), 1(II), 1(III), and 2, by diagonalizing the matrix of the electronic Hamiltonian plus the Breit-Pauli SO Hamiltonian. The MRSDCI calculations not including core orbital correlation through the single and double excitations are also performed with the AV5Z and ACV5Z basis sets. The Davidson corrections (Q0) are added to both the Λ-S and Ω state energies. Vibrational eigenstates for the obtained X1Σ+ and X0+ PECs are calculated by solving the time-independent Schrödinger equation with the grid method. Thus, the effects of basis set, core orbital correlation, and the Davidson correction on the X1Σ+ and X0+ PECs of LiCl are investigated by comparing the spectroscopic constants calculated from the PECs with one another and with experiment. It is confirmed that to accurately predict the spectroscopic constants we need to include core-electron correlation in the CI expansion and use the basis sets designed to describe core-valence correlation, i.e., ACVnZ. The SO PECs presented in this paper will be of help in the future study of diatomic alkali halide dynamics.

  11. Electron-impact excitation of the low-lying electronic states of HCN

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Tanaka, H.; Srivastava, S. K.; Wicke, B. G.

    1977-01-01

    The first study of the low-energy electron-impact excitation of low-lying electronic transitions in the HCN molecule is reported. Measurements were made at incident electron energies of 11.6 and 21.6 eV in the energy-loss range of 3-10 eV, and at scattering angles of 20-130 deg. Inelastic scattering spectra were placed on the absolute cross-section scale by determining first the ratio of inelastic-to-elastic scattering cross sections, and then separately measuring the absolute elastic scattering cross section. Several new electronic transitions are observed which are intrinsically overlapped in the molecule itself. Assignments of these electronic transitions are suggested. These assignments are based on present spectroscopic and cross-sections measurements, high-energy electron scattering spectra, optical absorption spectra, and ab initio molecular orbital calculations.

  12. The fate of water deposited in the low-lying northern plains

    NASA Technical Reports Server (NTRS)

    Carr, M. H.

    1993-01-01

    Many large outflow channels terminate in the low-lying northern plains. If the outflow channels formed by running water, as appears likely, then standing bodies of water must have accumulated at the ends of the channels. Most of the observed channels, and hence the bodies of water, are post-Noachian. They formed after the period for which we have the most abundant evidence of climate change. While it has been speculated that the post-Noachian period has experienced large, episodic, climatic excursions, this paper takes the more conservative view that the climatic conditions on Mars, at least from mid-Hesperian onward, were mostly similar to the climatic conditions that prevail in the present epoch. Thus obliquity variations are taken into account, but massive climate changes induced by the floods are considered so improbable that they are ignored.

  13. On the low-lying states of MgO. II

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.; Lengsfield, B. H., III; Silver, D. M.; Yarkony, D. R.

    1981-01-01

    Using a double zeta plus polarization basis set of Slater orbitals, full valence MCSCF (FVMCSCF) calculations were performed for the low-lying states of MgO. For each state the FVMCSCF calculations were used to identify the important configurations which are then used in the MCSCF calculation and subsequently as references in a single and double excitation CI calculation. This approach is found to treat all states equivalently, with the maximum error in the computed transition energies and equilibrium bond lengths of 800/cm and approximately 0.03 A, respectively. The b 3 Sigma + state which has yet to be characterized experimentally is predicted to have a transition energy of approximately 8300/cm and a bond length of 1.79 A. A spectroscopic analysis of the potential curves indicates that their shapes are in quite reasonable agreement with the range of experimental results.

  14. Low Lying Spin Excitation in the Spin Ice Ho2Ti2O7

    SciTech Connect

    Ehlers, Georg; Mamontov, Eugene; Zamponi, Michaela M; Gardner, Jason S

    2010-01-01

    The high flux and low background of the new backscattering spectrometer at the SNS combine to produce an excellent signal to noise ratio, allowing us to investigate a low lying weak excitation never seen before in the spin ice, Ho{sub 2}Ti{sub 2}O{sub 7}. This non-dispersive excitation has been observed at E = 26.3 {mu}eV below 100 K but is resolution limited only below {approx}65 K. It is indifferent to magnetic fields below {mu}{sub 0}H = 4.5 T, at 1.6 K. These characteristics help us to identify the excitation as due to the nuclear spin system.

  15. Spectroscopy of low-lying states in neutron-deficient astatine and francium nuclei

    NASA Astrophysics Data System (ADS)

    Jakobsson, U.; Uusitalo, J.; Auranen, K.; Badran, H.; Cederwall, B.; Cox, D. M.; Grahn, T.; Greenlees, P. T.; Julin, R.; Juutinen, S.; HerzáÅ, A.; Konki, J.; Leino, M.; Mallaburn, M.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Rahkila, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Sorri, J.; Stolze, S.

    2015-10-01

    Low-lying states in neutron-deficient astatine and francium nuclei have been studied by means of in-beam and delayed spectroscopy. The 13/2+ state has been observed in francium nuclei with a similar down-sloping trend as in neighbouring astatine and bismuth isotopes, as a function of decreasing neutron number. A systematic trend can also now be seen for the 1/2+ state both in astatine and francium nuclei, where the level energy decreases steeply as a function of neutron number when moving further away from the neutron shell closure. This trend is very similar between astatine nuclei and their francium isotones. Moreover, shape coexistence has been observed between the 13/2+ state and the spherical 9/2- ground state in 203Fr and 205Fr.

  16. Spectroscopy of low-lying states in neutron-deficient astatine and francium nuclei

    SciTech Connect

    Jakobsson, U. Cederwall, B.; Uusitalo, J.; Auranen, K.; Badran, H.; Cox, D. M.; Grahn, T.; Greenlees, P. T.; Julin, R.; Juutinen, S.; Herzáň, A.; Konki, J.; Leino, M.; Mallaburn, M.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Rahkila, P.; Sandzelius, M.; Sarén, J.; and others

    2015-10-15

    Low-lying states in neutron-deficient astatine and francium nuclei have been studied by means of in-beam and delayed spectroscopy. The 13/2{sup +} state has been observed in francium nuclei with a similar down-sloping trend as in neighbouring astatine and bismuth isotopes, as a function of decreasing neutron number. A systematic trend can also now be seen for the 1/2{sup +} state both in astatine and francium nuclei, where the level energy decreases steeply as a function of neutron number when moving further away from the neutron shell closure. This trend is very similar between astatine nuclei and their francium isotones. Moreover, shape coexistence has been observed between the 13/2{sup +} state and the spherical 9/2{sup −} ground state in {sup 203}Fr and {sup 205}Fr.

  17. On the low-lying states of MgO. II

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.; Lengsfield, B. H., III; Silver, D. M.; Yarkony, D. R.

    1981-01-01

    Using a double zeta plus polarization basis set of Slater orbitals, full valence MCSCF (FVMCSCF) calculations were performed for the low-lying states of MgO. For each state the FVMCSCF calculations were used to identify the important configurations which are then used in the MCSCF calculation and subsequently as references in a single and double excitation CI calculation. This approach is found to treat all states equivalently, with the maximum error in the computed transition energies and equilibrium bond lengths of 800/cm and approximately 0.03 A, respectively. The b 3 Sigma + state which has yet to be characterized experimentally is predicted to have a transition energy of approximately 8300/cm and a bond length of 1.79 A. A spectroscopic analysis of the potential curves indicates that their shapes are in quite reasonable agreement with the range of experimental results.

  18. Low-Lying ππ* States of Heteroaromatic Molecules: A Challenge for Excited State Methods.

    PubMed

    Prlj, Antonio; Sandoval-Salinas, María Eugenia; Casanova, David; Jacquemin, Denis; Corminboeuf, Clémence

    2016-06-14

    The description of low-lying ππ* states of linear acenes by standard electronic structure methods is known to be challenging. Here, we broaden the framework of this problem by considering a set of fused heteroaromatic rings and demonstrate that standard electronic structure methods do not provide a balanced description of the two (typically) lowest singlet state (La and Lb) excitations. While the Lb state is highly sensitive to correlation effects, La suffers from the same drawbacks as charge transfer excitations. We show that the comparison between CIS/CIS(D) can serve as a diagnostic for detecting the two problematic excited states. Standard TD-DFT and even its spin-flip variant lead to inaccurate excitation energies and interstate gaps, with only a double hybrid functional performing somewhat better. The complication inherent to a balanced description of these states is so important that even CC2 and ADC(2) do not necessarily match the ADC(3) reference.

  19. Electron delocalization and aromaticity in low-lying excited states of archetypal organic compounds.

    PubMed

    Feixas, Ferran; Vandenbussche, Jelle; Bultinck, Patrick; Matito, Eduard; Solà, Miquel

    2011-12-14

    Aromaticity is a property usually linked to the ground state of stable molecules. Although it is well-known that certain excited states are unquestionably aromatic, the aromaticity of excited states remains rather unexplored. To move one step forward in the comprehension of aromaticity in excited states, in this work we analyze the electron delocalization and aromaticity of a series of low-lying excited states of cyclobutadiene, benzene, and cyclooctatetraene with different multiplicities at the CASSCF level by means of electron delocalization measures. While our results are in agreement with Baird's rule for the aromaticity of the lowest-lying triplet excited state in annulenes having 4nπ-electrons, they do not support Soncini and Fowler's generalization of Baird's rule pointing out that the lowest-lying quintet state of benzene and septet state of cyclooctatetraene are not aromatic.

  20. α-d resonances and the low-lying states of 6Li

    NASA Astrophysics Data System (ADS)

    Eskandarian, A.; Afnan, I. R.

    1992-12-01

    The low-lying states (below the 3-3H threshold) of the 6Li nucleus are generated using three-body models with two-body nonlocal separable interactions between the constituent particles. The positions and widths of the states are determined by searching for the eigenvalues of the kernel of the Faddeev equations in the complex energy plane. When appropriate (for T=0 states only), the results are compared with a separate determination of these quantities from the α-d scattering process. All experimentally observed levels are found. Given that the Coulomb interaction is not included in our calculations, agreement with experiment is favorable for both the positions and the widths of the resonances.

  1. Accurate MRCI calculations of the low-lying electronic states of the NCl molecule

    NASA Astrophysics Data System (ADS)

    Song, Ziyue; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue

    2017-03-01

    Characterization of 22 electronic states of NCl correlating to the two lowest dissociation channels are carried out using high level CASSCF/MRCI calculations with a sextuple-ζ basis set including Davidson modification, core-valence correlation correction and scalar relativistic effects. As far as we know, this radical has never been the preference of theoretical researchers and experimental investigations only concern the ground state and the two low-lying metastable states. Accurate potential energy curves, dissociation energies as well as the equilibrium constants are determined and avoided crossings between the Π symmetry are studied. Moreover, spin-orbit splitting of several states and transition probabilities and radiative lifetimes for some allowed or forbidden transitions are presented.

  2. Low-lying singlet and triplet electronic states of RhB.

    PubMed

    Borin, Antonio Carlos; Gobbo, João Paulo

    2008-05-08

    The low-lying XSigma+, a3Delta, A1Delta, b3Sigma+, B1Pi, c3Pi, C1Phi, D1Sigma+, E1Pi, d3Phi, and e3Pi electronic states of RhB have been investigated at the ab initio level, using the multistate multiconfigurational second-order perturbation (MS-CASPT2) theory, with extended atomic basis sets and inclusion of scalar relativistic effects. Among the eleven electronic states included in this work, only three (the X1Sigma+, D1Sigma+, and E1Pi states) have been investigated experimentally. Potential energy curves, spectroscopic constants, dipole moments, binding energies, and chemical bonding aspects are presented for all electronic states.

  3. Geometries and energy separations of low-lying states of YNH and NYH

    NASA Astrophysics Data System (ADS)

    Das, Kalyan K.; Balasubramanian, K.

    1990-11-01

    Complete active-space multiconfiguration self-consistent field followed by multireference configuration-interaction calculations are carried out on low-lying electronic states of YNH and NYH. We find the X 2Σ+ linear state of Y-N-H to be 55 kcal/mol more stable than the bent NYH and 59 kcal/mol more stable than the linear N-Y-H. Our calculations confirm the recent assignment of the first observed spectra generated by laser vaporization of Y metal + He/NH3. The theoretical dipole moment of the Y-N-H molecule (3.06 D) is in excellent agreement with an experimental value of 3.06 D obtained by Simard et al. The theoretical Y-N and N-H bond lengths are also in good agreement with the experimental results.

  4. Geometries and energy separations of low-lying states of YNH and NYH

    SciTech Connect

    Das, K.K.; Balasubramanian, K. )

    1990-11-01

    Complete active-space multiconfiguration self--consistent field followed by multireference configuration-interaction calculations are carried out on low-lying electronic states of YNH and NYH. We find the {ital X} {sup 2}{Sigma}{sup +} linear state of Y--N--H to be 55 kcal/mol more stable than the bent NYH and 59 kcal/mol more stable than the linear N--Y--H. Our calculations confirm the recent assignment of the first observed spectra generated by laser vaporization of Y metal + He/NH{sub 3}. The theoretical dipole moment of the Y--N--H molecule (3.06 D) is in excellent agreement with an experimental value of 3.06 D obtained by Simard {ital et} {ital al}. The theoretical Y--N and N--H bond lengths are also in good agreement with the experimental results.

  5. Microscopic structure of low-lying states in {sup 188,190,192}Os

    SciTech Connect

    Lo Iudice, N.; Sushkov, A. V.

    2008-11-15

    The phonon and quasiparticle structure of the low-lying states in {sup 188,190,192}Os is investigated within the microscopic quasiparticle-phonon model. An overall agreement with the data is obtained for energies and transitions. The properties of the 0{sup +} states are found to be correlated with the evolution of the nuclear shape toward the {gamma}-soft region. Special attention is devoted at the 4{sub 3}{sup +} state. This state is found to be composed of a large double-{gamma} phonon component coexisting with an even larger one-phonon hexadecapole piece. Such a mixed phonon structure explains the observed, apparently contradictory, properties of the 4{sub 3}{sup +} states in Os isotopes.

  6. "No-spin" states and low-lying structures in 130Xe and 136Xe

    NASA Astrophysics Data System (ADS)

    Ross, T. J.; Peters, E. E.; Chakraborty, A.; Crider, B. P.; Kumar, A.; Liu, S. H.; McEllistrem, M. T.; Prados-Estévez, F. M.; Vanhoy, J. R.; Yates, S. W.

    2015-05-01

    Inelastic neutron scattering on solid 130XeF2 and 136XeF2 targets was utilized to populate excited levels in 130Xe and 136Xe. When calculating nuclear matrix elements vital to the understanding of double-beta decay, it is important to have a clear understanding of the low-lying level structure of both the parent and daughter nucleus. Of particular relevance to double-beta decay searches are the assignments of 0+ states. We show here that in the case of 130Xe there are several discrepancies in the adopted level structure. We found that one previous 0+ candidate level (1590 keV) can be ruled out and assigned two additional candidates (2223 and 2242 keV). In 136Xe we question the previous assignment of a 0+ level at 2582 keV. Excitation function and angular distribution measurements were utilized to make spin and parity assignments of levels and place new transitions.

  7. Comprehensive theoretical studies on the low-lying electronic states of NiF, NiCl, NiBr, and NiI.

    PubMed

    Zou, Wenli; Liu, Wenjian

    2006-04-21

    The low-lying electronic states of the nickel monohalides, i.e., NiF, NiCl, NiBr, and NiI, are investigated by using multireference second-order perturbation theory with relativistic effects taken into account. For the energetically lowest 11 lambda-S states and 26 omega states there into, the potential energy curves and corresponding spectroscopic constants (vertical and adiabatic excitation energies, equilibrium bond lengths, vibrational frequencies, and rotational constants) are reported. The calculated results are grossly in very good agreement with those solid experimental data. In particular, the ground state of NiI is shown to be different from those of NiF, NiCl, and NiBr, being in line with the recent experimental observation. Detailed analyses are provided on those states that either have not been assigned or have been incorrectly assigned by previous experiments.

  8. Spectroscopic and theoretical studies of the low-lying states of BaO{sup +}

    SciTech Connect

    Bartlett, Joshua H.; VanGundy, Robert A.; Heaven, Michael C.

    2015-07-28

    The BaO{sup +} cation is of interest from the perspectives of electronic structure and the potential for cooling to ultra-cold temperatures. Spectroscopic data for the ion have been obtained using a two-color photoionization technique. The ionization energy for BaO was found to be 6.8123(3) eV. The ground state of BaO{sup +} was identified as X{sup 2}Σ{sup +}, and both vibrational and rotational constants were determined. Vibrationally resolved spectra were recorded for A{sup 2}Π, the first electronically excited state. These data yielded the term energy, vibrational frequency, and the spin-orbit interaction constant. Relativistic electronic structure calculations were carried out using multi-reference configuration interaction (MRCI), coupled cluster and density functional theory methods. Transition moments for the pure vibrational and A{sup 2}Π-X{sup 2}Σ{sup +} transitions were predicted using the MRCI method.

  9. Theoretical calculation of low-lying states of NaAr and NaXe

    NASA Technical Reports Server (NTRS)

    Laskowski, B. C.; Langhoff, S. R.; Stallcop, J. R.

    1981-01-01

    Potential curves as well as dipole moments and linking transition moments are calculated for the ground X 2 Sigma + and low lying excited A 2 Pi, B 2 Sigma +, C 2 Sigma +, (4) 2 Sigma +, (2) 2 Pi and (1) 2 Delta states of NaAr and NaXe. Calculations are performed using a self-consistent field plus configuration-interaction procedure with the core electrons replaced by an ab initio effective core potential. The potential curves obtained are found to be considerably less repulsive than the semiempirical curves of Pascale and Vandeplanque (1974) and to agree well with existing experimental data, although the binding energies of those states having potential minima due to van der Waals interactions are underestimated. Emission bands are also calculated for the X 2 Sigma + - C 2 Sigma + excimer transitions of NaAr and NaXe using the calculated transition moments and potential curves, and shown to agree well with experiment on the short-wavelength side of the maximum.

  10. Low-lying even parity meson resonances and spin-flavor symmetry revisited

    NASA Astrophysics Data System (ADS)

    García-Recio, C.; Geng, L. S.; Nieves, J.; Salcedo, L. L.; Wang, En; Xie, Ju-Jun

    2013-05-01

    We review and extend the model derived in Garcia-Recio et al. [Phys. Rev. D 83, 016007 (2011)] to address the dynamics of the low-lying even-parity meson resonances. This model is based on a coupled-channels spin-flavor extension of the chiral Weinberg-Tomozawa Lagrangian. This interaction is then used to study the S-wave meson-meson scattering involving members not only of the π octet, but also of the ρ nonet. In this work, we study in detail the structure of the SU(6)-symmetry-breaking contact terms that respect (or softly break) chiral symmetry. We derive the most general local (without involving derivatives) terms consistent with the chiral-symmetry-breaking pattern of QCD. After introducing sensible simplifications to reduce the large number of possible operators, we carry out a phenomenological discussion of the effects of these terms. We show how the inclusion of these pieces leads to an improvement of the description of the JP=2+ sector, without spoiling the main features of the predictions obtained in the original model in the JP=0+ and JP=1+ sectors. In particular, we find a significantly better description of the IG(JPC)=0+(2++), 1-(2++) and the I(JP)=(1)/(2)(2+) sectors, which correspond to the f2(1270), a2(1320), and K2*(1430) quantum numbers, respectively.

  11. Properties of the low-lying electronic states of phenanthrene: Exact PPP results

    SciTech Connect

    Chakrabarti, A.; Ramasesha, S.

    1996-10-05

    The authors report properties of the exact low-lying states of phenanthrene, its anion and dianion within the Pariser-Parr-Pople (PPP) model. The experimentally known singlet states of the neutral molecule are well reproduced by the model. The intensities for one and two photon absorption to various single states are also in good agreement with experiment. From the bond orders of these states, the authors predict the equilibrium geometries. The relaxation energies of these states, computed from charge-charge correlations and bond orders, are presented. The authors also present results of ring current calculations in the singlet ground state of phenanthrene. The authors have also reported energies, spin densities, bond orders, and relaxation energies of several triplet states and compared then with experiments as well as with other calculations, where available. The fine structure constants D and E, computed in the lowest triplet state, compare well with those obtained from experiments. These properties are also presented for the anions and the dianions. The PPP model in these cases predicts a low-energy (< 1 eV) dipole excitation. 31 refs., 4 figs., 9 tabs.

  12. Numerical simulation of a low-lying barrier island's morphological response to Hurricane Katrina

    USGS Publications Warehouse

    Lindemer, C.A.; Plant, N.G.; Puleo, J.A.; Thompson, D.M.; Wamsley, T.V.

    2010-01-01

    Tropical cyclones that enter or form in the Gulf of Mexico generate storm surge and large waves that impact low-lying coastlines along the Gulf Coast. The Chandeleur Islands, located 161. km east of New Orleans, Louisiana, have endured numerous hurricanes that have passed nearby. Hurricane Katrina (landfall near Waveland MS, 29 Aug 2005) caused dramatic changes to the island elevation and shape. In this paper the predictability of hurricane-induced barrier island erosion and accretion is evaluated using a coupled hydrodynamic and morphodynamic model known as XBeach. Pre- and post-storm island topography was surveyed with an airborne lidar system. Numerical simulations utilized realistic surge and wave conditions determined from larger-scale hydrodynamic models. Simulations included model sensitivity tests with varying grid size and temporal resolutions. Model-predicted bathymetry/topography and post-storm survey data both showed similar patterns of island erosion, such as increased dissection by channels. However, the model under predicted the magnitude of erosion. Potential causes for under prediction include (1) errors in the initial conditions (the initial bathymetry/topography was measured three years prior to Katrina), (2) errors in the forcing conditions (a result of our omission of storms prior to Katrina and/or errors in Katrina storm conditions), and/or (3) physical processes that were omitted from the model (e.g., inclusion of sediment variations and bio-physical processes). ?? 2010.

  13. Low-lying electronic states of LiF molecule with inner electrons correlation

    NASA Astrophysics Data System (ADS)

    Wan, Ming-jie; Huang, Duo-hui; Yang, Jun-sheng; Cao, Qi-long; Jin, Cheng-guo; Wang, Fan-hou

    2015-06-01

    The potential energy curves and dipole moments of the low-lying electronic states of LiF molecule are performed by using highly accurate multi-reference configuration interaction with Awcv5z basis sets. 1s, the inner shell of Li is considered as the closed orbit, which is used to characterise the spectroscopic properties of a manifold of singlet and triplet states. 16 electronic states correlate with two lowest dissociation channels Li(2S)+F(2P) and Li(2P)+F(2P) are investigated. Spectroscopic parameters of the ground state X1Σ+ have been evaluated and critically compared with the available experimental values and the other theoretical data. However, spectroscopic parameters of 13Π, 11Δ, 11Σ-, 11Π, 13Σ+, 23Σ+, 13Δ, 13Σ-, 23Π, 21Π, 33Π, 31Π and 33Σ+ states are studied for the first time. These 13 excited states have shallow potential wells, and the dispersion coefficients of these excited states are predicted. In additional, oscillator strengths of excited states at equilibrium distances are also predicted.

  14. Impulsive thermal x-ray emission from a low-lying coronal loop

    SciTech Connect

    Liu, Siming; Li, Youping; Fletcher, Lyndsay

    2013-06-01

    Understanding the relationship among different emission components plays an essential role in the study of particle acceleration and energy conversion in solar flares. In flares where gradual and impulsive emission components can be readily identified, the impulsive emission has been attributed to non-thermal particles. We carry out detailed analysis of Hα and X-ray observations of a GOES class B microflare loop on the solar disk. The impulsive hard X-ray emission, however, is found to be consistent with a hot, quasi-thermal origin, and there is little evidence of emission from chromospheric footpoints, which challenges conventional models of flares and reveals a class of microflares associated with dense loops. Hα observations indicate that the loop lies very low in the solar corona or even in the chromosphere and both emission and absorption materials evolve during the flare. The enhanced Hα emission may very well originate from the photosphere when the low-lying flare loop heats up the underlying chromosphere and reduces the corresponding Hα opacity. These observations may be compared with detailed modeling of flare loops with the internal kink instability, where the mode remains confined in space without apparent change in the global field shape, to uncover the underlying physical processes and to probe the structure of solar atmosphere.

  15. Pauli blocking in the low-lying, low-spin states of {sup 141}Pr

    SciTech Connect

    Scheck, M.; Choudry, S. N.; Elhami, E.; McEllistrem, M. T.; Mukhopadhyay, S.; Orce, J. N.; Yates, S. W.

    2008-09-15

    The low-lying, low-spin levels of {sup 141}Pr were investigated using (n,n{sup '}{gamma}) techniques. Level energies, branching ratios, and tentative spin assignments for more than 100 states, linked by nearly 300 transitions, were obtained from two angular distributions (E{sub n}=2.0 and 3.0 MeV) and an excitation function measurement (E{sub n}=1.5-3.2 MeV). The application of the Doppler-shift attenuation method led to the determination of lifetimes. The obtained spectroscopic data provide insight into the wave functions of the states observed. A detailed analysis of the [2{sub 1}{sup +} x d{sub 5/2}] and [2{sub 1}{sup +} x g{sub 7/2}] multiplets provides the first quantitative evidence for Pauli blocking in a spherical odd-mass nucleus. The unpaired particle is used to probe the microscopic structure of the first 2{sup +} state of the adjacent core nuclei {sup 140}Ce and {sup 142}Nd.

  16. A theoretical study on low-lying electronic states and spectroscopic properties of PH

    NASA Astrophysics Data System (ADS)

    Gao, Yufeng; Gao, Tao

    2014-01-01

    The low-lying electronic states (X3∑-, a1Δ, b1Σ+, A3Π, c1Π and 5∑-) of the PH species correlating with the first three dissociation channels have been investigated at the MRCI + Q/aug-cc-PV5Z level of theory. Accurate adiabatic potential energy curves and spectroscopic constants (Te, Re, ωeχe, ωe, Be, De) of these electronic states have been reported. Effect of the spin-orbit coupling on the A3Π and 5∑- states of the PH has been calculated, which lead to the spin-orbit-induced predissociation of the A3Π state. Electronic transition moment, Einstein coefficients and Franck-Condon factors for the A3Π - X3∑- system have been calculated. Dipole moment functions (μe) and radiative lifetime (τv‧) for the A3Π state has also been determined. The radiative lifetime for A3Π - X3∑- transition is computed and compared with the available data.

  17. Low-Lying S-States of Two-Electron Systems

    NASA Astrophysics Data System (ADS)

    Khan, Md. Abdul

    2014-04-01

    The energies of the low-lying bound S-states of some two-electron systems (treating them as three-body systems) like negatively charged hydrogen, neutral helium, positively charged-lithium, beryllium, carbon, oxygen, neon, argon and negatively charged muonium and exotic positronium ions have been calculated employing hyperspherical harmonics expansion method. The matrix elements of two-body interactions involve Raynal-Revai coefficients which are particularly essential for the numerical solution of three-body Schrődinger equation when the two-body potentials are other from Coulomb or harmonic. The technique has been applied for to two-electron ions 1H- (Z = 1) to 40Ar16+ (Z = 18), negatively charged-muonium Mu- and exotic positronium ion Ps-(e + e - e -) considering purely Coulomb interaction. The available computer facility restricted reliable calculations up to 28 partial waves (i.e. K m = 28) and energies for higher K m have been obtained by applying an extrapolation scheme suggested by Schneider.

  18. Potential energy curves for the ground and low-lying excited states of CuAg

    SciTech Connect

    Alizadeh, Davood; Shayesteh, Alireza E-mail: ashayesteh@ut.ac.ir; Jamshidi, Zahra E-mail: ashayesteh@ut.ac.ir

    2014-10-21

    The ground and low-lying excited states of heteronuclear diatomic CuAg are examined by multi-reference configuration interaction (MRCI) method. Relativistic effects were treated and probed in two steps. Scalar terms were considered using the spin-free DKH Hamiltonian as a priori and spin-orbit coupling was calculated perturbatively via the spin-orbit terms of the Breit-Pauli Hamiltonian based on MRCI wavefunctions. Potential energy curves of the spin-free states and their corresponding Ω components correlating with the separated atom limits {sup 2}S(Cu) + {sup 2}S(Ag) and {sup 2}D(Cu) + {sup 2}S(Ag) are obtained. The results are in fine agreement with the experimental measurements and tentative conclusions for the ion-pair B0{sup +} state are confirmed by our theoretical calculations. Illustrative results are presented to reveal the relative importance and magnitude of the scalar and spin-orbit effects on the spectroscopic properties of this molecule. Time dependent density functional theory calculations, using the LDA, BLYP, B3LYP, and SAOP functionals have been carried out for CuAg and the accuracy of TD-DFT has been compared with ab initio results.

  19. Process-based model predictions of hurricane induced morphodynamic change on low-lying barrier islands

    USGS Publications Warehouse

    Plant, Nathaniel G.; Thompson, David M.; Elias, Edwin; Wang, Ping; Rosati, Julie D.; Roberts, Tiffany M.

    2011-01-01

    Using Delft3D, a Chandeleur Island model was constructed to examine the sediment-transport patterns and morphodynamic change caused by Hurricane Katrina and similar storm events. The model setup included a coarse Gulf of Mexico domain and a nested finer-resolution Chandeleur Island domain. The finer-resolution domain resolved morphodynamic processes driven by storms and tides. A sensitivity analysis of the simulated morphodynamic response was performed to investigate the effects of variations in surge levels. The Chandeleur morphodynamic model reproduced several important features that matched observed morphodynamic changes. A simulation of bathymetric change driven by storm surge alone (no waves) along the central portion of the Chandeleur Islands showed (1) a general landward retreat and lowering of the island chain and (2) multiple breaches that increased the degree of island dissection. The locations of many of the breaches correspond with the low-lying or narrow sections of the initial bathymetry. The major part of the morphological change occurred prior to the peak of the surge when overtopping of the islands produced a strong water-level gradient and induced significant flow velocities.

  20. Many low-lying isomers of the cationic and neutral niobium trimer and tetramer

    NASA Astrophysics Data System (ADS)

    Fowler, Joseph E.; García, América; Ugalde, Jesus M.

    1999-10-01

    The experimentally interesting Nb3 and Nb4 clusters and their cations have been studied in great detail using density-functional methodology in conjunction with relativistic effective core potentials. Close attention has been paid to full optimization along the flat potential energy surfaces and numerous minima and several transition states have been characterized. The Nb3 cation is predicted to have a 3A'1 ground state with an equilibrium geometry of D3h symmetry. The ground state of the neutral is predicted to be a 2B1 state of C2v symmetry with two shorter bonds and one longer. The transition state for pseudorotation or ``peak'' atom interchange, however, lies only 0.01 kcal/mol higher in energy, implying a fluxional structure for the neutral species. The global minimum of the Nb4 cationic cluster is a C2v structure, Jahn-Teller distorted from the Td global minimum of the singlet neutral. Numerous other energetically low-lying stationary points are characterized for each species. We discuss the bonding features of these minima and relate our predictions to the existing experimental data.

  1. Microscopic description of low-lying M1 excitations in odd-mass actinide nuclei

    NASA Astrophysics Data System (ADS)

    Tabar, Emre; Yakut, Hakan; Kuliev, Ali Akbar

    2017-01-01

    A restoration method of a broken symmetry which allows self-consistent determination of the separable effective restoration forces is now adapted to odd-mass nuclei in order to restore violated rotational invariance (RI-) of the Quasiparticle Phonon Nuclear Model (QPNM) Hamiltonian. Because of the self-consistency of the method, these effective forces contain no arbitrary parameters. Within RI-QPNM, the properties of the low-lying magnetic dipole excitations in odd-mass deformed 229-233Th and 233-239U nuclei have been investigated for the first time. It has been shown that computed fragmentation of the M1 strengths below 4 MeV in these nuclei is much stronger than that in neighboring doubly even 228-232Th and 232-238U nuclei. For 235U the summed M1 strength in the energy range 1.5-2.8 MeV is in agreement with the relevant experimental data where the missing strength was extracted by means of a fluctuation analysis.

  2. Low-lying level structure of 56Cu and its implications for the rp process

    NASA Astrophysics Data System (ADS)

    Ong, W.-J.; Langer, C.; Montes, F.; Aprahamian, A.; Bardayan, D. W.; Bazin, D.; Brown, B. A.; Browne, J.; Crawford, H.; Cyburt, R.; Deleeuw, E. B.; Domingo-Pardo, C.; Gade, A.; George, S.; Hosmer, P.; Keek, L.; Kontos, A.; Lee, I.-Y.; Lemasson, A.; Lunderberg, E.; Maeda, Y.; Matos, M.; Meisel, Z.; Noji, S.; Nunes, F. M.; Nystrom, A.; Perdikakis, G.; Pereira, J.; Quinn, S. J.; Recchia, F.; Schatz, H.; Scott, M.; Siegl, K.; Simon, A.; Smith, M.; Spyrou, A.; Stevens, J.; Stroberg, S. R.; Weisshaar, D.; Wheeler, J.; Wimmer, K.; Zegers, R. G. T.

    2017-05-01

    The low-lying energy levels of proton-rich 56Cu have been extracted using in-beam γ -ray spectroscopy with the state-of-the-art γ -ray tracking array GRETINA in conjunction with the S800 spectrograph at the National Superconducting Cyclotron Laboratory at Michigan State University. Excited states in 56Cu serve as resonances in the 55Ni(p ,γ )56Cu reaction, which is a part of the rp process in type-I x-ray bursts. To resolve existing ambiguities in the reaction Q value, a more localized isobaric multiplet mass equation (IMME) fit is used, resulting in Q =639 ±82 keV. We derive the first experimentally constrained thermonuclear reaction rate for 55Ni(p ,γ )56Cu . We find that, with this new rate, the rp process may bypass the 56Ni waiting point via the 55Ni(p ,γ ) reaction for typical x-ray burst conditions with a branching of up to ˜40 % . We also identify additional nuclear physics uncertainties that need to be addressed before drawing final conclusions about the rp -process reaction flow in the 56Ni region.

  3. Structural Optimization by Quantum Monte Carlo: Investigating the Low-Lying Excited States of Ethylene.

    PubMed

    Barborini, Matteo; Sorella, Sandro; Guidoni, Leonardo

    2012-04-10

    We present full structural optimizations of the ground state and of the low lying triplet state of the ethylene molecule by means of Quantum Monte Carlo methods. Using the efficient structural optimization method based on renormalization techniques and on adjoint differentiation algorithms recently proposed [Sorella, S.; Capriotti, L. J. Chem. Phys.2010, 133, 234111], we present the variational convergence of both wave function parameters and atomic positions. All of the calculations were done using an accurate and compact wave function based on Pauling's resonating valence bond representation: the Jastrow Antisymmetrized Geminal Power (JAGP). All structural and wave function parameters are optimized, including coefficients and exponents of the Gaussian primitives of the AGP and the Jastrow atomic orbitals. Bond lengths and bond angles are calculated with a statistical error of about 0.1% and are in good agreement with the available experimental data. The Variational and Diffusion Monte Carlo calculations estimate vertical and adiabatic excitation energies in the ranges 4.623(10)-4.688(5) eV and 3.001(5)-3.091(5) eV, respectively. The adiabatic gap, which is in line with other correlated quantum chemistry methods, is slightly higher than the value estimated by recent photodissociation experiments. Our results demonstrate how Quantum Monte Carlo calculations have become a promising and computationally affordable tool for the structural optimization of correlated molecular systems.

  4. CASSCF/CI calculations of low-lying states and potential energy surfaces of Au3

    NASA Astrophysics Data System (ADS)

    Balasubramanian, K.; Liao, M. Z.

    1987-05-01

    Complete active space MCSCF (CASSCF) and second-order configuration interaction (SOCI) calculations of low-lying electronic states [2B2,2A1] of Au3 as well as the 1Σ+g state of Au2 are carried out. The bending potential energy surfaces of 2A1 and 2B2 states are also presented. A barrier is found in the potential energy surface of the 2A1 state in moving from the linear to bent structure. Two nearly-degenerate structures are found for the ground state. The 2Σ+u state arising from the linear structure with an Au-Au bond length of 2.66 Å is only 3.2 kcal/mol below the 2A1 bent state. The equilibrium geometry of the 2A1 state is an isosceles triangle with an apex angle of 54°. The Au3 cluster is found to be more stable than the gold dimer. The effect of d correlation is studied on Au2 by carrying out MRSDCI (multireference singles and doubles CI) calculations on the 1Σ+g state of Au2 which include excitations from the d orbitals.

  5. Theoretical studies of the low-lying states of ScO, ScS, VO, and VS

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

    1986-01-01

    Bonding in the low-lying states of ScO, ScS, VO, and VS is theoretically studied. Excellent agreement is obtained with experimental spectroscopic constants for the low-lying states of ScO and VO. The results for VS and ScS show that the bonding in the oxides and sulfides is similar, but that the smaller electronegativity in S leads to a smaller ionic component in the bonding. The computed D0 of the sulfides are about 86 percent of the corresponding oxides, and the low-lying excited states are lower in the sulfides than in the corresponding oxides. The CPF method is shown to be an accurate and cost-effective method for obtaining reliable spectroscopic constants for these systems.

  6. β decay of Si38,40 ( Tz=+5,+6 ) to low-lying core excited states in odd-odd P38,40 isotopes

    DOE PAGES

    Tripathi, Vandana; Lubna, R. S.; Abromeit, B.; ...

    2017-02-08

    Low-lying excited states in P38,40 have been identified in the β decay of Tz=+5,+6, Si38,40. Based on the allowed nature of the Gamow-Teller (GT) decay observed, these states are assigned spin and parity of 1+ and are core-excited 1p1h intruder states with a parity opposite to the ground state. The occurrence of intruder states at low energies highlights the importance of pairing and quadrupole correlation energies in lowering the intruder states despite the N=20 shell gap. Configuration interaction shell model calculations with the state-of-art SDPF-MU effective interaction were performed to understand the structure of these 1p1h states in the even-Amore » phosphorus isotopes. States in P40 with N=25 were found to have very complex configurations involving all the fp orbitals leading to deformed states as seen in neutron-rich nuclei with N≈28. The calculated GT matrix elements for the β decay highlight the dominance of the decay of the core neutrons rather than the valence neutrons.« less

  7. β decay of Si,4038 (Tz=+5 ,+6 ) to low-lying core excited states in odd-odd P,4038 isotopes

    NASA Astrophysics Data System (ADS)

    Tripathi, Vandana; Lubna, R. S.; Abromeit, B.; Crawford, H. L.; Liddick, S. N.; Utsuno, Y.; Bender, P. C.; Crider, B. P.; Dungan, R.; Fallon, P.; Kravvaris, K.; Larson, N.; Macchiavelli, A. O.; Otsuka, T.; Prokop, C. J.; Richard, A. L.; Shimizu, N.; Tabor, S. L.; Volya, A.; Yoshida, S.

    2017-02-01

    Low-lying excited states in P,4038 have been identified in the β decay of Tz=+5 ,+6 , Si,4038. Based on the allowed nature of the Gamow-Teller (GT) decay observed, these states are assigned spin and parity of 1+ and are core-excited 1p1h intruder states with a parity opposite to the ground state. The occurrence of intruder states at low energies highlights the importance of pairing and quadrupole correlation energies in lowering the intruder states despite the N =20 shell gap. Configuration interaction shell model calculations with the state-of-art SDPF-MU effective interaction were performed to understand the structure of these 1p1h states in the even-A phosphorus isotopes. States in 40P with N =25 were found to have very complex configurations involving all the f p orbitals leading to deformed states as seen in neutron-rich nuclei with N ≈28 . The calculated GT matrix elements for the β decay highlight the dominance of the decay of the core neutrons rather than the valence neutrons.

  8. Theoretical spectroscopic constants for the low-lying states of the oxides and sulfides of Mo and Tc

    NASA Technical Reports Server (NTRS)

    Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Pettersson, Lars G. M.; Siegbahn, Per E. M.

    1989-01-01

    Spectroscopic results were determined for the ground and low-lying states of the oxides and sulfides of Mo and Tc, using the single-reference-based modified coupled pair functional method of Ahlrichs et al. (1985) and Chong et al. (1986) and the multireference-based state-averaged CASSCF/MRCI method. Spectroscopic constants, dipole moments, Mulliken populations, and radiative lifetimes were calculated for selected low-lying states of these molecular systems. The spectroscopy of the MoS and TcS molecules was found to be quite analogous to the corresponding oxides.

  9. Theoretical spectroscopic constants for the low-lying states of the oxides and sulfides of Mo and Tc

    NASA Technical Reports Server (NTRS)

    Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Pettersson, Lars G. M.; Siegbahn, Per E. M.

    1989-01-01

    Spectroscopic results were determined for the ground and low-lying states of the oxides and sulfides of Mo and Tc, using the single-reference-based modified coupled pair functional method of Ahlrichs et al. (1985) and Chong et al. (1986) and the multireference-based state-averaged CASSCF/MRCI method. Spectroscopic constants, dipole moments, Mulliken populations, and radiative lifetimes were calculated for selected low-lying states of these molecular systems. The spectroscopy of the MoS and TcS molecules was found to be quite analogous to the corresponding oxides.

  10. Observations of Low-Lying Electronic States of NiD, and Multi-Isotope Analysis

    NASA Astrophysics Data System (ADS)

    Abbasi, Mahdi; Shayesteh, Alireza; Crozet, Patrick; Ross, Amanda J.

    2017-06-01

    Resolved laser induced fluorescence spectra of NiD, recorded at Doppler resolution between 11500 and 18000 {cm^{-1}}, have defined some 200 term energies in two of the three strongly-interacting, low-lying ({X ^2Δ}, {W ^2Π} and {V ^2Σ^+}) states of NiD associated with an Ni{^+(3d^9})-D^- configuration. Our observations span v = 0 - 5 in the lowest spin-orbit component of the ground state, {X_1 ^2Δ_{5/2} }, v = 0 - 3 in {X_2 ^2Δ_{3/2} } and v = 0 - 1 in {W_1 ^2Π_{3/2} }, the lower component of the {W ^2Π } state. Spin-orbit and rotation-electronic interactions are strong in NiD. Large parity splittings are seen, due to interactions with the unobserved ^2Σ^+ state. We have attempted a global, multi-isotope fit to reproduce observed term energies up to 6000 {cm^{-1}} in NiD and ^{58,60,62}NiH, in an extension of the `Supermultiplet' model proposed by Gray and co-workers, because fits with NiD term energies alone failed to converge to sensible solutions. Dunham-type parameters have been used to represent the unperturbed X ^2Δ, W ^2Π and V ^2Σ^+ states, with off-diagonal matrix elements (treating spin-orbit, L- and S-uncoupling effects) based on Ni^+ atomic properties. Some electronic Born-Oppenheimer breakdown terms were included in the model. The spectra show emission from several excited states close to the unique level populated by the single-mode laser. Bands of collisionally-induced fluorescence identify three levels (A (Ω = 5/2) v = 1, E (Ω = 3/2) v = 1 and I (Ω = 3/2) v = 0) that have not been reported before. Gray, Li, Nelis, and Field, {J. Chem. Phys. 95, 7164 (1991)

  11. Electronic and structural properties of low-lying excited states of vitamin B12.

    PubMed

    Lodowski, Piotr; Jaworska, Maria; Kornobis, Karina; Andruniów, Tadeusz; Kozlowski, Pawel M

    2011-11-17

    Time-dependent density functional theory (TD-DFT) has been applied to explore electronically excited states of vitamin B(12) (cyanocobalamin or CNCbl). To explain why the Co-C bond in CNCbl does not undergo photodissociation under conditions of simple photon excitation, electronically excited states have been computed along the Co-C(CN) stretched coordinate. It was found that the repulsive (3)(σ(Co-C) → σ*(Co-C)) triplet state drops in energy as the Co-C(CN) bond lengthens, but it does not become dissociative. Low-lying excited states were also computed as function of two axial bond lengths. Two energy minima have been located on the S(1)/CNCbl, as well as T(1)/CNCbl, surfaces. The full geometry optimization was carried out for each minimum and electronic properties associated with each optimized structure were analyzed in details. One minimum was described as excitation having mixed ππ*/MLCT (metal-to-ligand charge transfer) character, while the second as ligand-to-metal charge transfer (LMCT) transition. Neither of them, however, can be viewed as pure MLCT or LMCT transitions since additional excitation to or from σ-bonds (SB) of N-Co-C unit have also noticeable contributions. Inclusion of solvent altered the character of one of the excitations from ππ*/MLCT/SBLCT to ππ*/LMCT/LSBCT-type, and therefore, both of them gained significant contribution from LMCT/LSBCT transition. Finally, the nature of S(1) electronic state has been comparatively analyzed in CNCbl and MeCbl cobalamins.

  12. Searching for low-lying multi-particle thresholds in lattice spectroscopy

    SciTech Connect

    Mahbub, M. Selim; Kamleh, Waseem; Leinweber, Derek B.; Williams, Anthony G.

    2014-03-15

    We explore the Euclidean-time tails of odd-parity nucleon correlation functions in a search for the S-wave pion–nucleon scattering-state threshold contribution. The analysis is performed using 2+1 flavor 32{sup 3}×64 PACS-CS gauge configurations available via the ILDG. Correlation matrices composed with various levels of fermion source/sink smearing are used to project low-lying states. The consideration of 25,600 fermion propagators reveals the presence of more than one state in what would normally be regarded as an eigenstate-projected correlation function. This observation is in accord with the scenario where the eigenstates contain a strong mixing of single and multi-particle states but only the single particle component has a strong coupling to the interpolating field. Employing a two-exponential fit to the eigenvector-projected correlation function, we are able to confirm the presence of two eigenstates. The lower-lying eigenstate is consistent with a Nπ scattering threshold and has a relatively small coupling to the three-quark interpolating field. We discuss the impact of this small scattering-state contamination in the eigenvector projected correlation function on previous results presented in the literature. -- Highlights: • Correlation-matrix projected correlators reveal more than one state contributing. • Results are associated with strong mixing of single and multi-particle states in QCD. • A two-exponential fit confirms the presence of two QCD eigenstates. •The lower-lying eigenstate is consistent with a nucleon–pion scattering threshold. •The impact of this small contamination on the higher-lying state is examined.

  13. Anharmonic Franck-Condon simulation of the absorption and fluorescence spectra for the low-lying S1 and S2 excited states of pyridine.

    PubMed

    Wang, Huan; Zhu, Chaoyuan; Yu, Jian-Guo; Lin, Sheng Hsien

    2009-12-31

    Anharmonic effects of the absorption and fluorescence spectra of pyridine molecule are studied and analyzed for the two-low lying singlet excited states S(1)((1)B(1)) and S(2)((1)B(2)). The complete active space self-consistent field (CASSCF) method is utilized to compute equilibrium geometries and all 27 vibrational normal-mode frequencies for the ground state and the two excited states. The present calculations show that the frequency differences between the ground and two excited states are small for the ten totally symmetric vibrational modes so that the displaced oscillator approximation can be used for spectrum simulations. The Franck-Condon factors within harmonic approximation basically grasp the main features of molecular spectra, but simulated 0-0 transition energy position and spectrum band shapes are not satisfactorily good for S(1)((1)B(1)) absorption and fluorescence spectra in comparison with experiment observation. As the first-order anharmonic correction added to Franck-Condon factors, both spectrum positions and band shapes can be simultaneously improved for both absorption and fluorescence spectra. It is concluded that the present anharmonic correction produces a significant dynamic shifts for spectrum positions and improves spectrum band shapes as well. The detailed structures of absorption spectrum of S(2)((1)B(2)) state observed from experiment can be also reproduced with anharmonic Franck-Condon simulation, and these were not shown in the harmonic Franck-Condon simulation with either distorted or Duschinsky effects in the literature.

  14. Laser induced fluorescence and radiative lifetimes of the low-lying electronic states of gaseous AgF

    NASA Astrophysics Data System (ADS)

    Wang, He; Gole, James L.

    1993-06-01

    At the fringes of the visible region, two low-lying 1 (Ω=1) electronic states A'Ω1 and aΩ1 of gaseous AgF located ˜4300 cm-1 below the previously known lowest excited A0+ state have been excited for the first time in a silver vapor-fluorine reaction system. The A'Ω1-X 1Σ+ and a Ω1-X 1Σ+ band systems (also observed in chemiluminescence) have been excited and studied using pulsed laser induced fluorescence spectroscopy. The band system associated with the A'Ω1-X 1Σ+ transition has been rotationally analyzed. The UV fluorescence of the A0+ and B0+-X 1Σ+ transitions has also been excited. The radiative lifetimes of these four low-lying electronic states have been measured as 7.1 μs (A'Ω1), 9.1 μs (aΩ1), 240 ns (A0+), and 21 ns (B0+), respectively, revealing that the two Ω=1 states are of triplet character, while the two 0+ states are of singlet character. The observed low-lying states of AgF appear to dissociate adiabatically to neutral atoms in contrast to the apparent dissociation of the low-lying electronic states in CuF to ion pairs. The observation of the low-lying 1 states of AgF also indicates the existence of similar stable 1 states for the remaining silver halides, all of which should absorb visible photons. Major molecular constants of the newly observed A'Ω1 state of 107AgF are Te=24 950.71(10) cm-1, ΔG1/2=506.74(8) cm-1, Be=0.281 32(15) cm-1, De=0.116(60)×10-6 cm-1, and re=1.927 Å.

  15. Sea Level Rise Enhanced Halocarbon Production in Low-lying Coastal Ecosystem in the Southeastern US

    NASA Astrophysics Data System (ADS)

    Chow, A. T.; Conner, W.; Williams, T.; Song, B.

    2010-12-01

    Saltwater tides bring high concentrations of chloride and bromide inland where it mixes with terrestrial humic substances from surrounding forested watersheds and ferric/ferrous ions from shallow groundwater. With all the essential precursors (i.e., chloride, bromide, and humic substances) and catalysts (ferric/ferrous ions with sunlight), low-lying coastal ecosystems could be a hotspot for halocarbon formation. Fluctuating water levels and salinity due to the tidal cycle alter both redox reactions and water chemistry, influencing the formation and fate of halocarbons. A controlled study was conducted to confirm the abiotic formation of trihalomethanes (THMs) by the photo-Fenton reaction and the effects of the precursors on their formation. Four THM species, including chloroform (CHCl3), bromodichloromethane (CHBrCl2), dibromochloromethane (CHBr2Cl), and bromoform (CHBr3), were examined. Sets of aqueous solutions were prepared using filtered Waccamaw River samples and synthesized NaCl / NaBr, and Fe2(SO4)3 and H2O2 solutions. Solutions were enclosed in quartz tubes and exposed for 7 days to natural sunlight. Although total THM formation increased with DOC concentration, the reactivity of C in forming THM was relatively consistent across DOC concentrations, with an average of 2.6 nmol-THM mmol-C-1. The reactivity in forming THMs through the photo-Fenton reaction was significantly lower than that in chlorinated water. Reactivity generally ranged from 3-20 mmol-THM mol-C-1. The differences in reactivity suggested that greater yield of THMs could be produced under the right reaction condition. In particular, the study showed that bromide increases the reactivity of DOC in forming THMs and enhances the formation of brominated THMs. The bromine substitution factor in the NaCl treatment ranged from 19 to 24% but increased to 43 and 46% when NaBr was added. Results suggest that increased salinity and bromide concentration in saltwater-impacted coastal ecosystems could

  16. The water budget of a coastal low-lying wetland area at the German Baltic Coast

    NASA Astrophysics Data System (ADS)

    Bronstert, Axel; Graeff, Thomas; Selle, Benny; Salzmann, Thomas; Franck, Christian; Miegel, Konrad

    2016-04-01

    that despite low slope, sandy soils and forest vegetation, the catchment's hydrology is dominated by quick discharge components, for which the near-surface groundwater and the reaction for open water surfaces are the main cause. The seasonality of the area's discharge is characterized by the formation of quick discharge components mainly during the winter half-year, and by the retention effect of the lowland/fen. This retention is especially high in summer, when the surface and ground water levels have decreased due to high evaporation rates and the discharge out of the area may cease. The magnitude of the area's outflow thus generally depends on the catchment's water level. Due to the possible backlog of surface water caused by high water levels of the Baltic Sea, the direction of flow may reverse episodically. In the subareas between the trenches of the lowland, vertical exchange processes from precipitation and evaporation dominate. The lateral sub-surface interaction from/to the Baltic Sea is rather small due to the particular low local subsurface hydraulic conductivity and the very small hydraulic gradient. In summary, it can be said that this coastal low-lying wetland in the restoration phase shows rather heterogeneous hydrological processes and water balance. Characteristic are the high relevance of the subsurface processes and a strong seasonal variation, i.e. very low discharge rates in summer (except for summer convective rain storms) and considerable discharge rates in winter. The anthropogenic interventions in those coastal areas during the last two centuries have changed their water balance exceedingly. The interaction with the Baltic Sea via groundwater exchange under the dunes is very small.

  17. Multireference configuration interaction study of the 27 low-lying states of the PF+ cation

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue

    2017-06-01

    This paper studied the spectroscopic parameters and vibrational properties of 27 Λ-S and 60 Ω states of PF+ cation. The 27 Λ-S states were the X2Π, A2Σ+, B2Π, C2Σ-, D2Δ, a4Σ-, b4Π, c4Σ+, d4Δ, 22Σ+, 32Σ+, 42Σ+, 22Σ-, 32Σ-, 32Π, 42Π, 52Π, 62Π, 22Δ, 32Δ, 12Φ, 24Σ-, 34Σ-, 24Π, 34Π, 16Σ-, and 16Π, which were generated from the first four dissociation limits. The 60 Ω states were produced from the 27 Λ-S states. All the potential energy curves were calculated with the CASSCF method, which was followed by the icMRCI + Q approach. The a4Σ-, b4Π, and D2Δ states were inverted with the spin-orbit coupling effect accounted for. The 24Π, 24Σ-, 22Δ, 32Δ, 32Σ+, 42Σ+, 12Φ, and 22Σ- states were repulsive whether the spin-orbit coupling effect was included or not, but the 52Π and D2Δ states became repulsive only with the spin-orbit coupling effect included. The C2Σ- state was very weakly bound. The a4Σ- state had one barrier. The avoided crossings existed between the a4Σ- and 24Σ- states, the 22Σ+ and 32Σ+ states as well as the D2Δ and 22Δ states. Core-valence correlation and scalar relativistic corrections were taken into account. The extrapolation to the complete basis set limit was done. The spectroscopic parameters and vibrational properties were determined. The transition dipole moments were calculated and the Franck-Condon factors of some electric dipole transitions were evaluated. The spin-orbit coupling effect on the spectroscopic and vibrational properties was discussed.

  18. On the nature of the low lying singlet states of anthracene

    NASA Astrophysics Data System (ADS)

    Bree, A.; Leyderman, A.; Taliani, C.

    1986-03-01

    An analysis of the two-photon fluorescence excitation spectrum (TPES) of anthracene-h 10 and anthracene-d 10 in mixed crystal in the spectral range of 26000-31000 cm -1 at 4.2 K is presented. The two photon forbidden pure electronic origin of anthracene is particularly intense in fluorene mixed crystals because of the perturbation of the host matrix. In addition, a number of b lu vibrations give rise to a vibronic coupling with a second excited electronic state of total symmetry A g at about 29400 cm -1. The nature of this second excited state is discussed.

  19. Fermilab Tevatron quadrupoles

    SciTech Connect

    Cooper, W.E.; Fisk, H.E.; Gross, D.A.; Lundy, R.A.; Schmidt, E.E.; Turkot, F.

    1983-03-01

    Details on the design, construction, and performance tests of Energy Saver/Doubler quadrupoles are presented along with recent data from the test of a special high gradient low beta prototype quadrupole.

  20. Theoretical spectroscopic parameters for the low-lying states of the second-row transition metal hydrides

    NASA Technical Reports Server (NTRS)

    Langhoff, Stephen R.; Pettersson, Lars G. M.; Bauschlicher, Charles W., Jr.; Partridge, Harry

    1987-01-01

    A systematic analysis of the low-lying states of all of the second-row transition metal (TM) hydrides except CdH is reported. The calculations included the dominant relativistic contributions through the use of the relativistic effective core potentials of Hay and Wadt (1985). Electron correlation was incorporated, using single-plus-double configuration interaction, the coupled pair functional (CPF) formalism of Ahlrichs et al. (1985), and the Chong and Langhoff (1986) modified version of the CPF method. The spectroscopic parameters D(e), r(e), and mu(e) determined for the low-lying states are compared with the available experimental data and previous theoretical results. In contrast to the first-row TM hydrides studied earlier (Chong et al., 1986), the spectroscopic constants for the second-row TM hydrides were found to be much less sensitive to the level of correlation treatment.

  1. Theoretical spectroscopic parameters for the low-lying states of the second-row transition metal hydrides

    NASA Technical Reports Server (NTRS)

    Langhoff, Stephen R.; Pettersson, Lars G. M.; Bauschlicher, Charles W., Jr.; Partridge, Harry

    1987-01-01

    A systematic analysis of the low-lying states of all of the second-row transition metal (TM) hydrides except CdH is reported. The calculations included the dominant relativistic contributions through the use of the relativistic effective core potentials of Hay and Wadt (1985). Electron correlation was incorporated, using single-plus-double configuration interaction, the coupled pair functional (CPF) formalism of Ahlrichs et al. (1985), and the Chong and Langhoff (1986) modified version of the CPF method. The spectroscopic parameters D(e), r(e), and mu(e) determined for the low-lying states are compared with the available experimental data and previous theoretical results. In contrast to the first-row TM hydrides studied earlier (Chong et al., 1986), the spectroscopic constants for the second-row TM hydrides were found to be much less sensitive to the level of correlation treatment.

  2. Effects of pairing correlation on the low-lying quasiparticle resonance in neutron drip-line nuclei

    NASA Astrophysics Data System (ADS)

    Kobayashi, Yoshihiko; Matsuo, Masayuki

    2016-01-01

    We discuss the effects of pairing correlation on quasiparticle resonance. We analyze in detail how the width of the low-lying (Ex≲ 1 MeV) quasiparticle resonance is governed by the pairing correlation in the neutron drip-line nuclei. We consider the {}^{46}Si + n system to discuss the low-lying p-wave quasiparticle resonance. Solving the Hartree-Fock-Bogoliubov equation in coordinate space with the scattering boundary condition, we calculate the phase shift, the elastic cross section, the resonance width, and the resonance energy. We find that the pairing correlation has the effect of reducing the width of the quasiparticle resonance that originates from a particle-like orbit in weakly bound nuclei.

  3. Microscopic investigation of the low-lying magnetic dipole transitions in the odd-mass 155-169Ho isotopes

    NASA Astrophysics Data System (ADS)

    Tabar, E.; Kuliev, A.

    2017-08-01

    The low-lying magnetic dipole (M1) strength in deformed odd-mass 155-169Ho nuclei is investigated using rotational invariant (RI-) Quasiparticle Phonon Nuclear Model (QPNM). The gross features and fragmentation of the scissors mode in 165Ho is well reproduced by RI-QPNM calculations. The systematics of the low-energy M1 excitation in Ho isotopic chain is discussed with respect to summed strength. Besides, the results for M1 excitations in odd-mass Ho isotopes are compared with the systematics of the scissors mode in the neighbouring even-even nuclei. The obtained results generally match the systematic and trends typical for the scissors motion. In addition to the low-lying M1 excitations, a M1 giant resonance in the 7-15 MeV energy region is predicted for 155-169Ho nuclei in the present study.

  4. Low-lying excited states in armchair polyacene within Pariser-Parr-Pople model: A density matrix renormalization group study

    SciTech Connect

    Das, Mousumi

    2014-03-28

    We studied the nature of the ground state and low-lying excited states of armchair polyacene oligomers (Polyphenanthrene) within long-range Pariser-Parr-Pople model Hamiltonian with up to 14 monomers using symmetrized density matrix renormalization group technique. The ground state of all armchair polyacenes studied is found to be singlet. The results show that lowest singlet dipole allowed excited state has higher energy for armchair polyacenes as compared to linear fused polyacenes. Moreover, unlike linear fused polyacenes, the lowest singlet excited state of these oligomers is always found to lie below the lowest dipole forbidden two-photon state indicating that these armchair polyacene oligomers strongly fluoresce. The calculations of low-lying excitations on singly and triply electron doped armchair polyacene oligomers show a low energy band with strong transition dipole moment that coupled to charge conductivity. This implies armchair polyacene posses novel field-effect transistor properties.

  5. Identification of the one-quadrupole phonon 21,ms+ state of 204Hg

    NASA Astrophysics Data System (ADS)

    Stegmann, R.; Stahl, C.; Rainovski, G.; Pietralla, N.; Stoyanov, C.; Carpenter, M. P.; Janssens, R. V. F.; Lettmann, M.; Möller, T.; Möller, O.; Werner, V.; Zhu, S.

    2017-07-01

    One-phonon states of vibrational nuclei with mixed proton-neutron symmetry have been observed throughout the nuclear chart besides the mass A ≈ 200 region. Very recently, it has been proposed that the 22+ state of 212Po is of isovector nature. This nucleus has two valence protons and two valence neutrons outside the doubly-magic 208Pb nucleus. The stable isotope 204Hg, featuring two valence-proton and valence-neutron holes, with respect to 208Pb, is the particle-hole mirror of 212Po. In order to compare the properties of low-lying isovector excitations in these particle-hole mirror nuclei, we have studied 204Hg by using the projectile Coulomb-excitation technique. The measured absolute B (M 1 ;22+ → 21+) strength of 0.20 (2) μN2 indicates that the 22+ level of 204Hg is at least the main fragment of the 21,ms+ state. For the first time in this mass region, both lowest-lying, one-quadrupole phonon excitations are established together with the complete set of their decay strengths. This allows for a microscopic description of their structures, achieved in the framework of the Quasi-particle Phonon Model.

  6. Ab initio calculations of low-lying electronic states of vinyl chloride

    NASA Astrophysics Data System (ADS)

    Chang, Jia-Lin; Chen, Yit-Tsong

    2002-05-01

    The equilibrium geometries, vibrational frequencies, excitation energies, and oscillator strengths of vinyl chloride in the ground and five lowest-lying excited singlet states have been calculated using MP2, CIS, CASSCF, and MRCI methods with the 6-311++G** basis set. The geometries and vibrational frequencies of the ground and excited states are utilized to compute Franck-Condon factors. Calculated vibronic spectra for the transitions from the ground state to these five excited states are in agreement with experiment at 52 500-60 000 cm-1, with major contributions from the Ã(1 1A″)←X˜(1A') and C˜(2 1A')←X˜(11A') transitions. In this study, two spin-forbidden transitions of b˜(1 3A″)←X˜(11A') and c˜(2 3A&')←X˜(11A') are calculated to locate in 45 000-54 000 cm-1, and could be responsible for the observed one-photon absorption spectrum due to an intensity borrowing caused by the spin-orbit coupling of the Cl atom. Based on calculation, we speculate that upon the excitation of vinyl chloride at 193 nm the b˜(1 3A″) or c˜(2 3A″) excited state, instead of the (π,π*), is initially prepared prior to the subsequent photodissociation processes.

  7. Impact of the electron environment on the lifetime of the {sup 229}Th{sup m} low-lying isomer

    SciTech Connect

    Karpeshin, F. F.; Trzhaskovskaya, M. B.

    2007-11-15

    The question of the lifetime of the {sup 229}Th{sup m} low-lying isomer is considered in light of current experimental research. A strong effect of the electron shell on lifetime is demonstrated, depending on the energy of the isomer. Calculations are performed within the framework of the multiconfiguration Dirac-Fock method. The calculated lifetime ranges from around 1 min down to 10{sup -5} s. Prospects for further experimental research of the isomer are discussed.

  8. Simultaneous description of low-lying positive and negative parity states in spd, sdf and spdf interacting boson model

    NASA Astrophysics Data System (ADS)

    Jafarizadeh, M. A.; Majarshin, A. Jalili; Fouladi, N.

    2016-11-01

    In order to investigate negative parity states, it is necessary to consider negative parity-bosons additionally to the usual s- and d-bosons. The dipole and octupole degrees of freedom are essential to describe the observed low-lying collective states with negative parity. An extended interacting boson model (IBM) that describes pairing interactions among s, p, d and f-boson based on affine SU(1, 1) Lie algebra in the quantum phase transition (QPT) field, such as spd-IBM, sdf-IBM and spdf-IBM, is composed based on algebraic structure. In this paper, a solvable extended transitional Hamiltonian based on affine SU(1, 1) Lie algebra is proposed to describe low-lying positive and negative parity states between the spherical and deformed gamma-unstable shape. Three model of new algebraic solution for even-even nuclei are introduced. Numerical extraction to low-lying energy levels and transition rates within the control parameters of this evaluated Hamiltonian are presented for various N values. We reproduced the positive and negative parity states and our calculations suggest that the results of spdf-IBM are better than spd-IBM and sdf-IBM in this literature. By reproducing the experimental results, the method based on signature of the phase transition such as level crossing in the lowest excited states is used to provide a better description of Ru isotopes in this transitional region.

  9. Low-Lying Isomers of the B9- Boron Cluster: The Planar Molecular Wheel Versus Three-Dimensional Structures

    SciTech Connect

    Pan, Li-Li; Li, Jun; Wang, Lai S.

    2008-07-14

    The B9- cluster was found previously to be an unprecedented molecular wheel containing an octacoordinate planar boron with D8h symmetry in a combined photoelectron spectroscopy (PES) and theoretical study [H. J. Zhai et al., Angew. Chem. Int. Ed. 42, 6004 (2003)]. However, the PES spectra of B9- exhibit minor features that cannot be explained by the global minimum D8h structure, suggesting possible contributions from low-lying isomers at finite temperatures. Here we present Car-Parrinello molecular dynamics with simulated annealing simulations to fully explore the potential energy surface of B9- and search for low-lying isomers that may account for the minor PES features. We performed density functional theory (DFT) calculations with different exchange-correlation functionals and ab initio calculations at various levels of theory with different basis sets. Two three-dimensional low-lying isomers were found, both of Cs symmetry, 6.29 (Cs-2) and 10.23 (Cs-1) kcal/mol higher in energy than the D8h structure at the highest CCSD(T) level of theory. Calculated detachment transitions from the Cs-2 isomer are in excellent agreement with the minor features observed in the PES spectra of B9-. The B9- cluster proves to be a challenge for most DFT methods and the calculated relative energies strongly depend on the exchange-correlation functionals, providing an excellent example for evaluating the accuracies of various DFT methods.

  10. Smart Salinity Management in Low-lying Deltaic Areas: A Model Predictive Control Scheme Applied to a Test Canal

    NASA Astrophysics Data System (ADS)

    Ekin Aydin, Boran; Rutten, Martine; Oude Essink, Gualbert H. P.; Delsman, Joost; Abraham, Edo

    2017-04-01

    Saline groundwater exfiltration to surface water increases surface water salinization and degrades the water quality in low-lying deltaic areas. As the use of surface water is less appropriate for agricultural, industrial and drinking water production due to salinization, freshwater diverted from a river is often utilised for flushing canals and ditches in these areas. Current water management strategies for flushing control in low-lying deltaic areas have to be revised to mitigate expected negative effects of climate change, sea level increase and decreasing fresh water availability. Model predictive control (MPC) is a powerful control method that is increasingly used for managing water systems. The explicit consideration of constraints and multi-objective management are important features of MPC. In this study, an MPC scheme is developed and tested for combined salinity and water level control of a ditch/water course. Saline groundwater exfiltration fluxes and salinities are modelled by applying the Rapid Saline Groundwater Exfiltration Model (RSGEM) and used as known disturbances for the MPC scheme. The developed control scheme is applied to a test canal using real data from a Dutch polder (Polders are low lying and artificially drained areas surrounded by dikes, with a controlled surface water level below M.S.L) which is affected by high saline groundwater exfiltration. This test demonstrates the performance of the controller for a real scenario. Simulation results show that MPC can increase the operational efficiency of flushing operations.

  11. Low-lying electric-dipole strengths of Ca, Ni, and Sn isotopes imprinted on total reaction cross sections

    NASA Astrophysics Data System (ADS)

    Horiuchi, W.; Hatakeyama, S.; Ebata, S.; Suzuki, Y.

    2017-08-01

    Low-lying electric-dipole (E 1 ) strength of a neutron-rich nucleus contains information on neutron-skin thickness, deformation, and shell evolution. We discuss the possibility of making use of total reaction cross sections on 40Ca, 120Sn, and 208Pb targets to probe the E 1 strength of neutron-rich Ca, Ni, and Sn isotopes. They exhibit large enhancement of the E 1 strength at neutron number N >28 , 50, and 82, respectively, due to a change of the single-particle orbits near the Fermi surface participating in the transitions. The density distributions and the electric-multipole strength functions of those isotopes are calculated by the Hartree-Fock+BCS and the canonical-basis-time-dependent-Hartree-Fock-Bogoliubov methods, respectively, using three kinds of Skyrme-type effective interaction. The nuclear and Coulomb breakup processes are respectively described with the Glauber model and the equivalent photon method in which the effect of finite-charge distribution is taken into account. The three Skyrme interactions give different results for the total reaction cross sections because of different Coulomb breakup contributions. The contribution of the low-lying E 1 strength is amplified when the low-incident energy is chosen. With an appropriate choice of the incident energy and target nucleus, the total reaction cross section can be complementary to the Coulomb excitation for analyzing the low-lying E 1 strength of unstable nuclei.

  12. Multireference configuration interaction study of the 21 low-lying states of the OF radical

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue

    2017-09-01

    This paper calculated the potential energy curves of 21 Λ-S and 42 Ω states of the OF radical. The 21 Λ-S states were the X2Π, A2Σ-, B2Σ-, C2Δ, D2Σ+, E2Σ+, 22Π, a4Σ-, b4Δ, 24Σ-, 14Σ+, 14Π, 24Π, 32Σ+, 32Σ-, 32Π, 42Π, 52Π, 22Δ, 32Δ, and 12Φ, which arose from the first two dissociation limits. The 42 Ω states were generated from these Λ-S states. All the potential energy curves were calculated with the CASSCF method, which was followed by the icMRCI + Q approach. The 14Π, 24Π, 22Π, 42Π, 52Π, 32Σ+, and 32Δ states were repulsive whether the spin-orbit coupling effect included or not, but the A2Σ-, D2Σ+, 32Σ-, 22Δ, and 12Φ states became repulsive with the spin-orbit coupling effect included. Only the 16 Ω states were bound. With the spin-orbit coupling effect accounted for, the X2Π state was inverted among the bound states; the X2Π, a4Σ-, and E2Σ+ states were strongly bound; and the 32Π, b4Δ, B2Σ-, C2Δ, 24Σ-, and 14Σ+ states were very weakly bound. The spectroscopic and vibrational properties were determined. Franck-Condon factors of some transitions were evaluated. The spin-orbit coupling effect on the spectroscopic parameters and vibrational properties was discussed. It is very difficult to explore the X2Π, a4Σ-, and E2Σ+ states by observing the electronic transitions between them because all these strong transitions originating only from the highly-vibrational states of the X2Π or a4Σ- state. It is also very hard to detect the 32Π, b4Δ, B2Σ-, C2Δ, 24Σ-, and 14Σ+ states by observing the transitions originating from these states, because these states are very weakly bound and unstable, though some transitions originating from them are very strong. These results can well explain why the OF radical is very difficult to detect in a spectroscopic experiment by observing the electronic transitions between different states.

  13. Probing ground and low-lying excited states for HIO{sub 2} isomers

    SciTech Connect

    Souza, Gabriel L. C. de; Brown, Alex

    2014-12-21

    We present a computational study on HIO{sub 2} molecules. Ground state properties such as equilibrium structures, relative energetics, vibrational frequencies, and infrared intensities were obtained for all the isomers at the coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)) level of theory with the aug-cc-pVTZ-PP basis set and ECP-28-PP effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. The HOIO structure is confirmed as the lowest energy isomer. The relative energies are shown to be HOIO < HOOI < HI(O)O. The HO(O)I isomer is only stable at the density functional theory (DFT) level of theory. The transition states determined show interconversion of the isomers is possible. In order to facilitate future experimental identification, vibrational frequencies are also determined for all corresponding deuterated species. Vertical excitation energies for the three lowest-lying singlet and triplet excited states were determined using the configuration interaction singles, time-dependent density functional theory (TD-DFT)/B3LYP, TD-DFT/G96PW91, and equation of motion-CCSD approaches with the LANL2DZ basis set plus effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. It is shown that HOIO and HOOI isomers have excited states accessible at solar wavelengths (<4.0 eV) but these states have very small oscillator strengths (<2 × 10{sup −3})

  14. Probing ground and low-lying excited states for HIO2 isomers.

    PubMed

    de Souza, Gabriel L C; Brown, Alex

    2014-12-21

    We present a computational study on HIO2 molecules. Ground state properties such as equilibrium structures, relative energetics, vibrational frequencies, and infrared intensities were obtained for all the isomers at the coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)) level of theory with the aug-cc-pVTZ-PP basis set and ECP-28-PP effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. The HOIO structure is confirmed as the lowest energy isomer. The relative energies are shown to be HOIO < HOOI < HI(O)O. The HO(O)I isomer is only stable at the density functional theory (DFT) level of theory. The transition states determined show interconversion of the isomers is possible. In order to facilitate future experimental identification, vibrational frequencies are also determined for all corresponding deuterated species. Vertical excitation energies for the three lowest-lying singlet and triplet excited states were determined using the configuration interaction singles, time-dependent density functional theory (TD-DFT)/B3LYP, TD-DFT/G96PW91, and equation of motion-CCSD approaches with the LANL2DZ basis set plus effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. It is shown that HOIO and HOOI isomers have excited states accessible at solar wavelengths (<4.0 eV) but these states have very small oscillator strengths (<2 × 10(-3)).

  15. Probing ground and low-lying excited states for HIO2 isomers

    NASA Astrophysics Data System (ADS)

    de Souza, Gabriel L. C.; Brown, Alex

    2014-12-01

    We present a computational study on HIO2 molecules. Ground state properties such as equilibrium structures, relative energetics, vibrational frequencies, and infrared intensities were obtained for all the isomers at the coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)) level of theory with the aug-cc-pVTZ-PP basis set and ECP-28-PP effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. The HOIO structure is confirmed as the lowest energy isomer. The relative energies are shown to be HOIO < HOOI < HI(O)O. The HO(O)I isomer is only stable at the density functional theory (DFT) level of theory. The transition states determined show interconversion of the isomers is possible. In order to facilitate future experimental identification, vibrational frequencies are also determined for all corresponding deuterated species. Vertical excitation energies for the three lowest-lying singlet and triplet excited states were determined using the configuration interaction singles, time-dependent density functional theory (TD-DFT)/B3LYP, TD-DFT/G96PW91, and equation of motion-CCSD approaches with the LANL2DZ basis set plus effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. It is shown that HOIO and HOOI isomers have excited states accessible at solar wavelengths (<4.0 eV) but these states have very small oscillator strengths (<2 × 10-3).

  16. The role of the low-lying dark nπ* states in the photophysics of pyrazine: a quantum dynamics study.

    PubMed

    Sala, Matthieu; Lasorne, Benjamin; Gatti, Fabien; Guérin, Stéphane

    2014-08-14

    The excited state dynamics of pyrazine has attracted considerable attention in the last three decades. It has long been recognized that after UV excitation, the dynamics of the molecule is impacted by strong non-adiabatic effects due to the existence of a conical intersection between the B2u(ππ*) and B3u(nπ*) electronic states. However, a recent study based on trajectory surface hopping dynamics simulations suggested the participation of the Au(nπ*) and B2g(nπ*) low-lying dark electronic states in the ultrafast radiationless decay of the molecule after excitation to the B2u(ππ*) state. The purpose of this work was to pursue the investigation of the role of the Au(nπ*) and B2g(nπ*) states in the photophysics of pyrazine. A linear vibronic coupling model hamiltonian including the four lowest excited electronic states and the sixteen most relevant vibrational degrees of freedom was constructed using high level XMCQDPT2 electronic structure calculations. Wavepacket propagations using the MCTDH method were then performed and used to simulate the absorption spectrum and the electronic state population dynamics of the system. Our results show that the Au(nπ*) state plays an important role in the photophysics of pyrazine.

  17. Low-lying excited states and nonradiative processes of 9-methyl-2-aminopurine.

    PubMed

    Trachsel, Maria A; Lobsiger, Simon; Schär, Tobias; Leutwyler, Samuel

    2014-01-28

    The UV spectrum of the adenine analogue 9-methyl-2-aminopurine (9M-2AP) is investigated with one- and two-color resonant two-photon ionization spectroscopy at 0.3 and 0.05 cm(-1) resolution in a supersonic jet. The electronic origin at 32,252 cm(-1) exhibits methyl torsional subbands that originate from the 0A1'' (l = 0) and 1E(″) (l = ±1) torsional levels. These and further torsional bands that appear up to 00 (0)+230 cm(-1) allow to fit the threefold (V3) barriers of the torsional potentials as |V3''|=50 cm(-1) in the S0 and |V3'|=126 cm(-1) in the S1 state. Using the B3LYP density functional and correlated approximate second-order coupled cluster CC2 methods, the methyl orientation is calculated to be symmetric relative to the 2AP plane in both states, with barriers of V3''=20 cm(-1) and V3'=115 cm(-1). The 00 (0) rotational band contour is 75% in-plane (a/b) polarized, characteristic for a dominantly long-axis (1)ππ(*) excitation. The residual 25% c-axis polarization may indicate coupling of the (1)ππ(*) to the close-lying (1)nπ(*) state, calculated at 4.00 and 4.01 eV with the CC2 method. However, the CC2 calculated (1)nπ oscillator strength is only 6% of that of the (1)ππ(*) transition. The (1)ππ(*) vibronic spectrum is very complex, showing about 40 bands within the lowest 500 cm(-1). The methyl torsion and the low-frequency out-of-plane ν1' and ν2' vibrations are strongly coupled in the (1)ππ(*) state. This gives rise to many torsion-vibration combination bands built on out-of-plane fundamentals, which are without precedence in the (1)ππ(*) spectrum of 9H-2-aminopurine [S. Lobsiger, R. K. Sinha, M. Trachsel, and S. Leutwyler, J. Chem. Phys. 134, 114307 (2011)]. From the Lorentzian broadening needed to fit the 00 (0) contour of 9M-2AP, the (1)ππ(*) lifetime is τ ⩾ 120 ps, reflecting a rapid nonradiative transition.

  18. MRCI calculations of the low-lying electronic states of CuC

    NASA Astrophysics Data System (ADS)

    Liu, C.; Zhang, S. D.

    2015-06-01

    The four electronic states (2Σ-, 2Π, 4Σ-, and 4Π) of CuC corresponding to the lowest dissociation limits Cu(2 S g ) + C(3 P g ) are calculated by using multi-reference configuration interaction method with Davidson correction (MRCI + Q) approach in combination with the effective core potentials (ECPs) basis sets LANLTZ for the Cu atom and 6-311+g( d) basis sets for the C atom. The calculation covers the internuclear distance ranging from 0.04 to 0.54 nm, and the equilibrium bond length R e and the vertical excited energy T e are determined directly. The potential energy curves (PECs) show that the lowest two states are the 4Σ- and 2Π, and 4Σ- is the ground state where the 2Π state is higher than 4Σ- about 0.28 eV. With the potentials, all of the vibrational levels and rotational constants are predicted by numerically solving the radial Schröbinger equation of nuclear motion. Then the spectroscopic data of ωe, ωe x e, B e, and αe are obtained after data fitting which are compared with theoretical results currently available.

  19. Ab initio study on the low-lying excited states of gas-phase PH+ cation including spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Li, Xia; Zhang, Xiaomei; Yan, Bing

    2015-05-01

    Ab initio calculations have been performed on the low-lying excited and ground states of PH+. The potential energy curves (PECs) of the Λ-S states were calculated with multi-reference configuration interaction (MRCI) method along with the basis sets at 5-ξ level. In order to improve the PECs, the Davidson(+Q) correction and the Scalar relativistic effect are included. The corresponding spectroscopic constants were determined and good agreements with the available measurement were found. The interactions of the A2Δ-4Π and 12Σ+-4Π by the spin-orbit coupling (SOC) effect were well described by the spin-orbit matrix elements. The SOC effect makes the original 8 Λ-S states split into 15 Ω states. The Ω = 1/2 state generated from the X2Π state is confirmed to the ground Ω state. And the SOC splitting for the X2Π is calculated to be 294 cm-1. The SOC effect has large effect on the PECs of the A2Δ and 12Σ+ states, leading to much more shallow potential wells as well as potential barriers. The analysis of the wavefunction for the Ω states shows that the strong spin-orbit interaction exists near the crossing points of the PECs for the Λ-S states. The transition dipole moments (TDMs) of transitions A2Δ-X2Π and 12Σ--X2Π are evaluated with the MRCI wavefunction. Based on the TDMs along with the calculated Franck-Condon factors, the radiative lifetimes for the selected vibrational levels of A2Δ and 12Σ- states are predicted at the microseconds (μs). Good agreement with the measurement shows that the lowest vibrational level for A2Δ state is almost uninfluenced by the perturbation via the SOC effect.

  20. A Chemiluminescent and Laser-Induced Fluorescent Probe of a New Low-Lying A‧Ω = 1 State of Gaseous AgF

    NASA Astrophysics Data System (ADS)

    Wang, H.; Gole, J. L.

    1993-09-01

    A new A‧ 1 (Ω = 1) state of AgF at the fringes of the visible region has been excited and analyzed. The chemiluminescence from this state, which is located ∼4300 cm-1 below the previously known lowest excited A 0+ state, is observed for the first time in a beam-gas reaction where silver molecules, Agx, are reacted with either atomic or molecular fluorine. Using pulsed laser-induced fluorescence, two vibrational bands (v‧, v″) = (0, 0) and (1, 0) have been rotationally resolved and electronic and rotational assignments have been obtained. Molecular constants which can reproduce the observed data with a standard deviation of 0.1 cm-1, the RKR potential energy curve, and the Franck-Condon factors for the A‧ 1-X1Σ+ transition have been determined. The internal energy distributions of the reaction product AgF molecules are studied by vibrational intensity analysis and rotational simulation calculations. The possible reaction paths to produce the excited A‧, state from either the four-center Ag2‧ + F2 or Agx (x ≥ 3) + F reactions and the formation of ground state AgF molecules are discussed through consideration of reactant-product correlations and energetics. The dissociation energy of the newly observed A‧ 1 state is 4649 ± 1400 cm-1. The observation of this low-lying Ω = 1 state indicates the existence of similar stable Ω = 1 states for the remaining silver halides, all of which should readily absorb visible photons. Their existence, which may have implications for the detailed understanding of the photographic process, provides intermediate states for multiple-resonance laser excitation and multiphoton laser ionization.

  1. Low-lying excited states and nonradiative processes of 9-methyl-2-aminopurine

    SciTech Connect

    Trachsel, Maria A.; Lobsiger, Simon; Schär, Tobias; Leutwyler, Samuel

    2014-01-28

    The UV spectrum of the adenine analogue 9-methyl-2-aminopurine (9M-2AP) is investigated with one- and two-color resonant two-photon ionization spectroscopy at 0.3 and 0.05 cm{sup −1} resolution in a supersonic jet. The electronic origin at 32 252 cm{sup −1} exhibits methyl torsional subbands that originate from the 0A{sub 1}{sup ′′} (l = 0) and 1E{sup ″} (l = ±1) torsional levels. These and further torsional bands that appear up to 0{sub 0}{sup 0}+230 cm{sup −1} allow to fit the threefold (V{sub 3}) barriers of the torsional potentials as |V{sub 3}{sup ′′}|=50 cm{sup −1} in the S{sub 0} and |V{sub 3}{sup ′}|=126 cm{sup −1} in the S{sub 1} state. Using the B3LYP density functional and correlated approximate second-order coupled cluster CC2 methods, the methyl orientation is calculated to be symmetric relative to the 2AP plane in both states, with barriers of V{sub 3}{sup ′′}=20 cm{sup −1} and V{sub 3}{sup ′}=115 cm{sup −1}. The 0{sub 0}{sup 0} rotational band contour is 75% in-plane (a/b) polarized, characteristic for a dominantly long-axis {sup 1}ππ{sup *} excitation. The residual 25% c-axis polarization may indicate coupling of the {sup 1}ππ{sup *} to the close-lying {sup 1}nπ{sup *} state, calculated at 4.00 and 4.01 eV with the CC2 method. However, the CC2 calculated {sup 1}nπ oscillator strength is only 6% of that of the {sup 1}ππ{sup *} transition. The {sup 1}ππ{sup *} vibronic spectrum is very complex, showing about 40 bands within the lowest 500 cm{sup −1}. The methyl torsion and the low-frequency out-of-plane ν{sub 1}{sup ′} and ν{sub 2}{sup ′} vibrations are strongly coupled in the {sup 1}ππ{sup *} state. This gives rise to many torsion-vibration combination bands built on out-of-plane fundamentals, which are without precedence in the {sup 1}ππ{sup *} spectrum of 9H-2-aminopurine [S. Lobsiger, R. K. Sinha, M. Trachsel, and S. Leutwyler, J. Chem. Phys. 134, 114307 (2011)]. From the Lorentzian

  2. Low-lying quasibound rovibrational states of H2 16O**

    NASA Astrophysics Data System (ADS)

    Szidarovszky, Tamás; Császár, Attila G.

    2013-08-01

    A complex coordinate scaling (CCS) method is described allowing the quantum chemical computation of quasibound (also called resonance or metastable) rovibrational states of strongly bound triatomic molecules. The molecule chosen to test the method is H2 16O, for which an accurate global potential energy surface, a previous computation of a few resonance states via the complex absorbing potential (CAP) method, and some Feshbach (J = 0, where J is the quantum number characterising overall rotations of the molecule) and shape (J ≠ 0) resonances measured via a state-selective, triple-resonance technique are all available. Characterisation of the computed resonance states is performed via probability density plots based on CCS rovibrational wavefunctions. Such plots provide useful details about the physical nature of the resonance states. Based on the computations and the resonance plots, the following useful facts about the resonance states investigated are obtained: (a) Feshbach resonances are formed by accumulation of a large amount of energy in either the non-dissociative bending or symmetric streching modes, excitations by more than five quanta are not uncommon; (b) there are several resonance states with low and medium bending excitation, the latter are different from the states observed somewhat below dissociation by the same triple-resonance technique; (c) several types of dissociation bahavior can be identified, varying greatly among the states; (d) several pairs of J = 0 and J = 1 Feshbach resonance states can be identified which differ by rigid-rotor type energies; and (e) the lifetimes of the assigned J = 1 rovibrational Feshbach resonances are considerably longer than the lifetimes of their J = 0 vibrational counterparts.

  3. Evaluating the 100 year floodplain as an indicator of flood risk in low-lying coastal watersheds

    NASA Astrophysics Data System (ADS)

    Sebastian, A.; Brody, S.; Bedient, P. B.

    2013-12-01

    The Gulf of Mexico is the fastest growing region in the United States. Since 1960, the number of housing units built in the low-lying coastal counties has increased by 246%. The region experiences some of the most intense rainfall events in the country and coastal watersheds are prone to severe flooding characterized by wide floodplains and ponding. This flooding is further exacerbated as urban development encroaches on existing streams and waterways. While the 100 year floodplain should play an important role in our ability to develop disaster resilient communities, recent research has indicated that existing floodplain delineations are a poor indicator of actual flood losses in low-lying coastal regions. Between 2001 and 2005, more than 30% of insurance claims made to FEMA in the Gulf Coast region were outside of the 100 year floodplain and residential losses amounted to more than $19.3 billion. As population density and investments in this region continue to increase, addressing flood risk in coastal communities should become a priority for engineers, urban planners, and decision makers. This study compares the effectiveness of 1-D and a 2-D modeling approaches to spatially capture flood claims from historical events. Initial results indicate that 2-D models perform much better in coastal environments and may serve better for floodplain modeling helping to prevent unintended losses. The results of this study encourage a shift towards better engineering practices using existing 2-D models in order to protect resources and provide guidance for urban development in low-lying coastal regions.

  4. On the low-lying states of WO - A comparison with CrO and MoO

    NASA Technical Reports Server (NTRS)

    Nelin, C. J.; Bauschlicher, C. W., Jr.

    1985-01-01

    The four low-lying states of WO were investigated and compared with similar states of CrO and MoO. For all these systems the ground state is 5 Pi, but the ordering of the upper states is different between WO and either CrO or MoO. The difference in the state ordering arises in part from the fact that in WO all of the states are formed from W(+) in a d4S1 configuration, whereas in both CrO and MoO some states are formed from the d5 configuration and others from the d4S1 configuration.

  5. Primary transitions between the yrast superdeformed band and low-lying normal deformed states in {sup 194}Pb

    SciTech Connect

    Hauschild, K.; Bernstein, L.A.; Becker, J.A.

    1996-12-31

    The observation of one-step `primary` gamma-ray transitions directly linking the superdeformed (SD) states to the normal deformed (ND) low-lying states of known excitation energies (E{sub x}), spins and parities (J{sup {pi}}) is crucial to determining the E{sub x} and J{sup {pi}} of the SD states. With this knowledge one can begin to address some of the outstanding problems associated with SD nuclei, such as the identical band issue, and one can also place more stringent restrictions on theoretical calculations which predict SD states and their properties. Brinkman, et al., used the early implementation of the GAMMASPHERE spectrometer array (32 detectors) and proposed a single, candidate {gamma} ray linking the {sup 194}Pb yrast SD band to the low-lying ND states in {sup 194}Pb. Using 55 detectors in the GAMMASPHERE array Khoo, et al., observed multiple links between the yrast SD band in {sup 194}Hg and the low-lying level scheme and conclusively determined E{sub x} and J of the yrast SD states. Here the authors report on an experiment in which Gammasphere with 88 detectors was used and the E{sub x} and J{sup {pi}} values of the yrast SD states in {sup 194}Pb were uniquely determined. Twelve one-step linking transitions between the yrast SD band and low-lying states in {sup 194}Pb have been identified, including the transition proposed by Brinkman. These transitions have been placed in the level scheme of {sup 194}Pb using coincidence relationships and agreements between the energies of the primary transitions and the energy differences in level spacings. Furthermore, measurements of angular asymmetries have yielded the multipolarities of the primaries which have allowed J{sup {pi}} assignments of the {sup 194}Pb SD states to be unambiguously determined for the first time without a priori assumptions about the character of SD bands. A study performed in parallel to this work using the EUROGAM-II array reports similar, but somewhat less extensive, results.

  6. Low-lying isomeric state in {sup 80}Ga from the {beta}{sup -} decay of {sup 80}Zn

    SciTech Connect

    LicA, R.; Marginean, N.; Ghita, D.G.; and others

    2012-10-20

    A new level scheme was constructed for {sup 80}Ga which is significantly different from the one previously reported. The excitation energy of a new low-lying state recently reported in [2] was identified at 22.4 keV. Properties of the level scheme suggest that the ground state has spin J = 6 and the first excited state has spin J = 3. The spin assignments are in agreement with laser spectroscopy values previously measured. Our work provides the first evidence for the J = 6 being the ground state.

  7. Spin (1/2){sup +}, spin (3/2){sup +}, and transition magnetic moments of low lying and charmed baryons

    SciTech Connect

    Sharma, Neetika; Dahiya, Harleen; Chatley, P. K.; Gupta, Manmohan

    2010-04-01

    Magnetic moments of the low lying and charmed spin (1/2){sup +} and spin (3/2){sup +} baryons have been calculated in the SU(4) chiral constituent quark model ({chi}CQM) by including the contribution from cc fluctuations. Explicit calculations have been carried out for the contribution coming from the valence quarks, ''quark sea'' polarizations and their orbital angular momentum. The implications of such a model have also been studied for magnetic moments of the low lying spin (3/2){sup +{yields}}(1/2){sup +} and (1/2){sup +{yields}}(1/2){sup +} transitions as well as the transitions involving charmed baryons. The predictions of {chi}CQM not only give a satisfactory fit for the baryons where experimental data is available but also show improvement over the other models. In particular, for the case of {mu}(p), {mu}({Sigma}{sup +}), {mu}({Xi}{sup 0}), {mu}({Lambda}), Coleman-Glashow sum rule for the low lying spin (1/2){sup +} baryons and {mu}({Delta}{sup +}), {mu}({Omega}{sup -}) for the low lying spin (3/2){sup +} baryons, we are able to achieve an excellent agreement with data. For the spin (1/2){sup +} and spin (3/2){sup +} charmed baryon magnetic moments, our results are consistent with the predictions of the QCD sum rules, light cone sum rules and spectral sum rules. For the cases where light quarks dominate in the valence structure, the sea and orbital contributions are found to be fairly significant however, they cancel in the right direction to give the correct magnitude of the total magnetic moment. On the other hand, when there is an excess of heavy quarks, the contribution of the quark sea is almost negligible, for example, {mu}({Omega}{sub c}{sup 0}), {mu}({Lambda}{sub c}{sup +}), {mu}({Xi}{sub c}{sup +}), {mu}({Xi}{sub c}{sup 0}), {mu}({Omega}{sub cc}{sup +}), {mu}({Omega}{sup -}), {mu}({Omega}{sub c}*{sup 0}), {mu}({Omega}{sub cc}*{sup +}), and {mu}({Omega}{sub ccc}*{sup ++}). The effects of configuration mixing and quark masses have also been

  8. On the low-lying states of WO - A comparison with CrO and MoO

    NASA Technical Reports Server (NTRS)

    Nelin, C. J.; Bauschlicher, C. W., Jr.

    1985-01-01

    The four low-lying states of WO were investigated and compared with similar states of CrO and MoO. For all these systems the ground state is 5 Pi, but the ordering of the upper states is different between WO and either CrO or MoO. The difference in the state ordering arises in part from the fact that in WO all of the states are formed from W(+) in a d4S1 configuration, whereas in both CrO and MoO some states are formed from the d5 configuration and others from the d4S1 configuration.

  9. Hierarchy of the low-lying excitations for the (2 + 1)-dimensional q = 3 Potts model in the ordered phase

    NASA Astrophysics Data System (ADS)

    Nishiyama, Yoshihiro

    2017-03-01

    The (2 + 1)-dimensional q = 3 Potts model was simulated with the exact diagonalization method. In the ordered phase, the elementary excitations (magnons) are attractive, forming a series of bound states in the low-energy spectrum. We investigate the low-lying spectrum through a dynamical susceptibility, which is readily tractable with the exact diagonalization method via the continued-fraction expansion. As a result, we estimate the series of (scaled) mass gaps, m 2 , 3 , 4 /m1 (m1: single-magnon mass), in proximity to the transition point.

  10. Simultaneous description of low-lying positive and negative parity bands in heavy even-even nuclei

    NASA Astrophysics Data System (ADS)

    Ganev, H. G.

    2014-05-01

    The low-lying spectra including the first few excited positive and negative parity bands of some heavy even-even nuclei from the rare earth and actinide mass regions are investigated within the framework of the symplectic interacting vector boson model with the Sp(12,R) dynamical symmetry group. Symplectic dynamical symmetries allow the change of the number of excitation quanta or phonons building the collective states, providing for larger representation spaces and richer subalgebraic structures to incorporate more complex nuclear spectra. The theoretical predictions for the energy levels and the electromagnetic transitions between the collective states of the ground-state band and Kπ=0- band are compared with experiment and some other collective models incorporating octupole and/or dipole degrees of freedom. The energy staggering, which is a sensitive indicator of the octupole correlations in even-even nuclei, is also calculated and compared with experiment. The results obtained for the energy levels, energy staggering, and transition strengths reveal the relevance of the dynamical symmetry used in the model to simultaneously describe both positive and negative parity low-lying collective bands.

  11. Low-lying π∗ resonances associated with cyano groups: A CAP/SAC-CI study

    NASA Astrophysics Data System (ADS)

    Ehara, Masahiro; Kanazawa, Yuki; Sommerfeld, Thomas

    2017-01-01

    The complex absorbing potential (CAP)/symmetry-adapted cluster-configuration interaction (SAC-CI) method is applied to low-lying π∗ resonance states of molecules containing one or two cyano (CN) groups. Benchmark calculations are carried out comparing the non-variational and approximate variational approach of SAC-CI and studying the selection threshold of operators. Experimental resonance positions from electron transmission spectroscopy (ETS) are reproduced provided the anticipated deviations due to vibronic effects are taken into account. Moreover, the calculated positions and widths agree well with those obtained in previous electron scattering calculations for HCN, CH3CN and their isonitriles. Based on our results, we suggest a reassignment of the experimental ETS of fumaronitrile and malononitrile. Our present results demonstrate again that the CAP/SAC-CI method reliably predicts low-lying π∗ resonances, and regarding the total numbers of molecules and resonances investigated, it is fair to say that it is presently the most extensively used high-level method in the temporary anion field.

  12. Strong Electron-Phonon Coupling Superconductivity Induced by a Low-Lying Phonon in IrGe

    SciTech Connect

    Hirai, Daigorou; Ali, Mazhar N.; Cava, Robert J.

    2014-02-26

    The physical properties of the previously reported superconductor IrGe and the Rh1-xIrxGe solid solution are investigated. IrGe has an exceptionally high superconducting transition temperature (Tc=4.7 K) among the isostructural 1:1 late-metal germanides MGe (M=Rh, Pd, Ir, and Pt). Specific-heat measurements reveal that IrGe has an anomalously low Debye temperature, originating from a low-lying phonon, compared to the other MGe phases. A large jump at Tc in the specific-heat data clearly indicates that IrGe is a strong coupling superconductor. In the Rh1-xIrxGe solid solution, a relationship between an anomalous change in lattice constants and the Debye temperature is observed. We conclude that the unusually high Tc for IrGe is likely due to strong electron–phonon coupling derived from the presence of a low-lying phonon.

  13. Potential energy curves and lifetimes of low-lying excited electronic states of CSe studied by configuration interaction method.

    PubMed

    Li, Rui; Sun, Erping; Jin, Mingxing; Xu, Haifeng; Yan, Bing

    2014-04-10

    In this work, we performed a high level ab initio study on the low-lying electronic states of CSe, utilizing MRCI+Q (the internally contracted multireference configuration interaction, and Davidson's correction) method with scalar relativistic and spin-orbit coupling effects taken into account. The potential energy curves of 18 Λ-S states associated with the lowest dissociation limit of CSe molecule, as well as those of 50 Ω states generated from the Λ-S states were computed. The spectroscopic parameters of bound states were evaluated, which agree well with existing theoretical and experimental results. With the aid of calculated spin-orbit matrix elements and the Λ-S compositional variation of the Ω states, the spin-orbit perturbations of low-lying states to the A(1)Π and a(3)Π states are analyzed. Finally, the transition dipole moments of A(1)Π, A'(1)Σ(+), a(3)Π0+, and a(3)Π1 to the ground X(1)Σ(+) state as well as the lifetimes of the four excited states were evaluated.

  14. Elastic response of the atomic nucleus in gauge space: Giant Pairing Vibrations

    NASA Astrophysics Data System (ADS)

    Bortignon, P. F.; Broglia, R. A.

    2016-09-01

    Due to quantal fluctuations, the ground state of a closed shell system A0 can become virtually excited in a state made out of the ground state of the neighbour nucleus \\vert gs(A_0+2) rangle ( \\vert gs(A_0-2) rangle ) and of two uncorrelated holes (particles) below (above) the Fermi surface. These J^{π} = 0+ pairing vibrational states have been extensively studied with two-nucleon transfer reactions. Away from closed shells, these modes eventually condense, leading to nuclear superfluidity and thus to pairing rotational bands with excitation energies much smaller than hbarω0, the energy separation between major shells. Pairing vibrations are the plastic response of the nucleus in gauge space, in a similar way in which low-lying quadrupole vibrations, i.e. surface vibrations with energies much smaller than hbarω0 whose eventual condensation leads to quadrupole deformed nuclei, provide an example of the plastic nuclear response in 3D space. While much is known, in particular concerning its damping, regarding the counterpart of quadrupole plastic modes, i.e. regarding the giant quadrupole resonances (GQR), J^{π} = 2+ elastic response of the nucleus with energies of the order of hbarω0, little is known regarding this subject concerning pairing modes (giant pairing vibrations, GPV). Consequently, the recently reported observation of L = 0 resonances, populated in the reactions 12C(18O,16O)14C and 13C(18O,16O)15C and lying at an excitation energy of the order of hbarω0, likely constitutes the starting point of a new field of research, that of the study of the elastic response of nuclei in gauge space. Not only that, but also the fact that the GPV have likely been serendipitously observed in these light nuclei when it has failed to show up in more propitious nuclei like Pb, provides unexpected and fundamental insight into the relation existing between basic mechanisms -Landau, doorway, compound damping- through which giant resonances acquire a finite lifetime, let

  15. Quadrupole ion traps.

    PubMed

    March, Raymond E

    2009-01-01

    The extraordinary story of the three-dimensional radiofrequency quadrupole ion trap, accompanied by a seemingly unintelligible theoretical treatment, is told in some detail because of the quite considerable degree of commercial success that quadrupole technology has achieved. The quadrupole ion trap, often used in conjunction with a quadrupole mass filter, remained a laboratory curiosity until 1979 when, at the American Society for Mass Spectrometry Conference in Seattle, George Stafford, Jr., of Finnigan Corp., learned of the Masters' study of Allison Armitage of a combined quadrupole ion trap/quadrupole mass filter instrument for the observation of electron impact and chemical ionization mass spectra of simple compounds eluting from a gas chromatograph. Stafford developed subsequently the mass-selective axial instability method for obtaining mass spectra from the quadrupole ion trap alone and, in 1983, Finnigan Corp. announced the first commercial quadrupole ion trap instrument as a detector for a gas chromatograph. In 1987, confinement of ions generated externally to the ion trap was demonstrated and, soon after, the new technique of electrospray ionization was shown to be compatible with the ion trap. Copyright 2009 Wiley Periodicals, Inc.

  16. Theoretical spectroscopy study of the low-lying electronic states of UX and UX+, X = F and Cl

    NASA Astrophysics Data System (ADS)

    Bross, David H.; Peterson, Kirk A.

    2015-11-01

    Spectroscopic constants (Te, re, B0, ωe, and ωexe) have been calculated for the low-lying electronic states of UF, UF+, UCl, and UCl+ using complete active space 2nd-order perturbation theory (CASPT2), with a series of correlation consistent basis sets. The latter included those based on both pseudopotential (PP) and all-electron Douglas-Kroll-Hess Hamiltonians for the U atom. Spin orbit (SO) effects were included a posteriori using the state interacting method using both PP and Breit Pauli (BP) operators, as well as from exact two-component methods for U+ and UF+. Complete basis set (CBS) limits were obtained by extrapolation where possible and the PP and BP calculations were compared at their respective CBS limits. The PP-based method was shown to be reliable in calculating spectroscopic constants, in particular when using the state interacting method with CASPT2 energies (SO-CASPT2). The two component calculations were limited by computational resources and could not include electron correlation from the nominally closed shell 6s and 6p orbitals of U. UF and UCl were both calculated to have Ω = 9/2 ground states. The first excited state of UCl was calculated to be an Ω = 7/2 state at 78 cm-1 as opposed to the same state at 435 cm-1 in UF, and the other low-lying states of UCl showed a similar compression relative to UF. Likewise, UF+ and UCl+ both have Ω = 4 ground states and the manifold of low-lying excited Ω = 3, 2, 1, 0 states was energetically closer together in UCl+ than in UF+, ranging up to 776 cm-1 in UF+ and only 438 cm-1 in UCl+. As in previous studies, the final PP-based SO-CASPT2 results for UF+ and UF agree well with experiment and are expected to be predictive for UCl and UCl+, which are reported here for the first time.

  17. Theoretical spectroscopy study of the low-lying electronic states of UX and UX{sup +}, X = F and Cl

    SciTech Connect

    Bross, David H.; Peterson, Kirk A.

    2015-11-14

    Spectroscopic constants (T{sub e}, r{sub e}, B{sub 0}, ω{sub e}, and ω{sub e}x{sub e}) have been calculated for the low-lying electronic states of UF, UF{sup +}, UCl, and UCl{sup +} using complete active space 2nd-order perturbation theory (CASPT2), with a series of correlation consistent basis sets. The latter included those based on both pseudopotential (PP) and all-electron Douglas-Kroll-Hess Hamiltonians for the U atom. Spin orbit (SO) effects were included a posteriori using the state interacting method using both PP and Breit Pauli (BP) operators, as well as from exact two-component methods for U{sup +} and UF{sup +}. Complete basis set (CBS) limits were obtained by extrapolation where possible and the PP and BP calculations were compared at their respective CBS limits. The PP-based method was shown to be reliable in calculating spectroscopic constants, in particular when using the state interacting method with CASPT2 energies (SO-CASPT2). The two component calculations were limited by computational resources and could not include electron correlation from the nominally closed shell 6s and 6p orbitals of U. UF and UCl were both calculated to have Ω = 9/2 ground states. The first excited state of UCl was calculated to be an Ω = 7/2 state at 78 cm{sup −1} as opposed to the same state at 435 cm{sup −1} in UF, and the other low-lying states of UCl showed a similar compression relative to UF. Likewise, UF{sup +} and UCl{sup +} both have Ω = 4 ground states and the manifold of low-lying excited Ω = 3, 2, 1, 0 states was energetically closer together in UCl{sup +} than in UF{sup +}, ranging up to 776 cm{sup −1} in UF{sup +} and only 438 cm{sup −1} in UCl{sup +}. As in previous studies, the final PP-based SO-CASPT2 results for UF{sup +} and UF agree well with experiment and are expected to be predictive for UCl and UCl{sup +}, which are reported here for the first time.

  18. Theoretical spectroscopy study of the low-lying electronic states of UX and UX(+), X = F and Cl.

    PubMed

    Bross, David H; Peterson, Kirk A

    2015-11-14

    Spectroscopic constants (Te, re, B0, ωe, and ωexe) have been calculated for the low-lying electronic states of UF, UF(+), UCl, and UCl(+) using complete active space 2nd-order perturbation theory (CASPT2), with a series of correlation consistent basis sets. The latter included those based on both pseudopotential (PP) and all-electron Douglas-Kroll-Hess Hamiltonians for the U atom. Spin orbit (SO) effects were included a posteriori using the state interacting method using both PP and Breit Pauli (BP) operators, as well as from exact two-component methods for U(+) and UF(+). Complete basis set (CBS) limits were obtained by extrapolation where possible and the PP and BP calculations were compared at their respective CBS limits. The PP-based method was shown to be reliable in calculating spectroscopic constants, in particular when using the state interacting method with CASPT2 energies (SO-CASPT2). The two component calculations were limited by computational resources and could not include electron correlation from the nominally closed shell 6s and 6p orbitals of U. UF and UCl were both calculated to have Ω = 9/2 ground states. The first excited state of UCl was calculated to be an Ω = 7/2 state at 78 cm(-1) as opposed to the same state at 435 cm(-1) in UF, and the other low-lying states of UCl showed a similar compression relative to UF. Likewise, UF(+) and UCl(+) both have Ω = 4 ground states and the manifold of low-lying excited Ω = 3, 2, 1, 0 states was energetically closer together in UCl(+) than in UF(+), ranging up to 776 cm(-1) in UF(+) and only 438 cm(-1) in UCl(+). As in previous studies, the final PP-based SO-CASPT2 results for UF(+) and UF agree well with experiment and are expected to be predictive for UCl and UCl(+), which are reported here for the first time.

  19. Theoretical spectroscopy study of the low-lying electronic states of UX and UX+, X = F and Cl

    DOE PAGES

    Bross, David H.; Peterson, Kirk A.

    2015-11-13

    Spectroscopic constants (Te, re, B0, ωe, ωexe) have been calculated for the low-lying electronic states of UF, UF+, UCl, and UCl+ using complete active space 2nd-order perturbation theory (CASPT2), with a series of correlation consistent basis sets. The latter included those based on both pseudopotential (PP) and all-electron Douglas-Kroll-Hess (DK) Hamiltonians for the U atom. Spin orbit effects were included a posteri using the state interacting method using both PP and Breit Pauli (BP) operators, as well as from exact two-component (X2C) methods for U+ and UF+. Complete basis set (CBS) limits were obtained by extrapolation where possible and themore » PP and BP calculations were compared at their respective CBS limits. The PP-based method was shown to be reliable in calculating spectroscopic constants, in particular when using the state interacting method with CASPT2 energies (SO-CASPT2). The two component calculations were limited by computational resources and could not include electron correlation from the nominally closed shell 6s and 6p orbitals of U. UF and UCl were both calculated to have Ω=9/2 ground states. The first excited state of UCl was calculated to be an Ω=7/2 state at 78 cm-1 as opposed to the same state at 435 cm-1 in UF, and the other low-lying states of UCl showed a similar compression relative to UF. Likewise UF+ and UCl+ both have Ω=4 ground states and the manifold of low-lying excited Ω = 3, 2, 1, 0 states were energetically closer together in UCl+ than in UF+, ranging up to 776 cm-1 in UF+ and only 438 cm-1 in UCl+. As in previous research, the final PP-based SO-CASPT2 results for UF+ and UF agree well with experiment, and are expected to be predictive for UCl and UCl+, which are reported here for the first time.« less

  20. Comparative study of the low-lying valence electronic states of carbon dioxide by high-resolution inelastic x-ray and electron scattering

    NASA Astrophysics Data System (ADS)

    Ni, Dong-Dong; Xu, Long-Quan; Liu, Ya-Wei; Yang, Ke; Hiraoka, Nozomu; Tsuei, Ku-Ding; Zhu, Lin-Fan

    2017-07-01

    We report a comparative study of low-lying valence electronic states of carbon dioxide by high-resolution inelastic x-ray and electron scattering. Momentum-transfer-dependent inelastic squared form factors for the two states 1Σu+ and 1Πu and generalized oscillator strength for the 9 eV feature from the ground state X1Σg+ have been derived from the inelastic x-ray scattering method at an impact photon energy around 10 keV, and the electron energy-loss spectra measured at an incident electron energy of 1500 eV. It is found from the comparison between the present results and the previous outcomes that the recent calculations taking the vibronic effects into consideration satisfactorily reproduce the inelastic squared form-factor profile for the 1Σu+ transition and the generalized oscillator strength profile for the 9 eV feature. However, the vibronic effects seem to play no role in the 1Πu transition. The difference existing between the inelastic x-ray scattering and electron energy-loss spectroscopy results in the larger momentum-transfer squared region may be attributed to the increasing role of the higher-order Born terms. Furthermore, the controversy concerning the designations of electronic states around 11 eV is solved by assigning the two peaks centered at 10.98 and 11.05 eV to the vibrational progression 1Σu+' and 1Σu+ , and the peak centered at 11.16 eV to the forbidden transition 21Δu based on the present results.

  1. Spin Tests of a Low-lying Monoplane in Flight and in the Free-spinning Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Seidman, Oscar; Mcavoy, William H

    1940-01-01

    Comparative full-scale and model spin tests were made with a low-lying monoplane in order to extend the available information as to the utility of the free-spinning wind tunnel as an aid in predicting full-scale spin characteristics. For a given control disposition the model indicated steeper spins than were actually obtained with the airplane, the difference being most pronounced for spins with elevators up. Recovery characteristics for the model, on the whole, agreed with those for the airplane, but a disagreement was noted for the case of recovery with elevators held full up. Free-spinning wind-tunnel tests are a useful aid in estimating spin characteristics of airplanes, but it must be appreciated that model results can give only general indications of full-scale behavior.

  2. Low-lying baryon masses using Nf=2 twisted mass clover-improved fermions directly at the physical pion mass

    NASA Astrophysics Data System (ADS)

    Alexandrou, C.; Kallidonis, C.

    2017-08-01

    The masses of the low-lying baryons are evaluated using an ensemble with two degenerate light twisted mass clover-improved quarks with mass tuned to reproduce the physical pion mass. The Iwasaki improved gluonic action is employed. The coupling constant value corresponds to a lattice spacing of a =0.0938 (3 )(2 ) fm , determined from the nucleon mass. We find that the clover term supresses isospin symmetry breaking as compared to our previous results using Nf=2 +1 +1 twisted mass fermions. The masses of the hyperons and charmed baryons evaluated using this ensemble are in agreement with the experimental values. We provide predictions for the mass of the doubly charmed Ξcc * , as well as of the doubly and triply charmed Ω s that have not yet been determined experimentally.

  3. The GSAM software: A global search algorithm of minima exploration for the investigation of low lying isomers of clusters

    NASA Astrophysics Data System (ADS)

    Marchal, Rémi; Carbonnière, Philippe; Pouchan, Claude

    2015-01-01

    The study of atomic clusters has become an increasingly active area of research in the recent years because of the fundamental interest in studying a completely new area that can bridge the gap between atomic and solid state physics. Due to their specific properties, such compounds are of great interest in the field of nanotechnology [1,2]. Here, we would present our GSAM algorithm based on a DFT exploration of the PES to find the low lying isomers of such compounds. This algorithm includes the generation of an intial set of structure from which the most relevant are selected. Moreover, an optimization process, called raking optimization, able to discard step by step all the non physically reasonnable configurations have been implemented to reduce the computational cost of this algorithm. Structural properties of GanAs m clusters will be presented as an illustration of the method.

  4. The GSAM software: A global search algorithm of minima exploration for the investigation of low lying isomers of clusters

    SciTech Connect

    Marchal, Rémi; Carbonnière, Philippe; Pouchan, Claude

    2015-01-22

    The study of atomic clusters has become an increasingly active area of research in the recent years because of the fundamental interest in studying a completely new area that can bridge the gap between atomic and solid state physics. Due to their specific properties, such compounds are of great interest in the field of nanotechnology [1,2]. Here, we would present our GSAM algorithm based on a DFT exploration of the PES to find the low lying isomers of such compounds. This algorithm includes the generation of an intial set of structure from which the most relevant are selected. Moreover, an optimization process, called raking optimization, able to discard step by step all the non physically reasonnable configurations have been implemented to reduce the computational cost of this algorithm. Structural properties of Ga{sub n}Asm clusters will be presented as an illustration of the method.

  5. Three-Dimensional Angular Momentum Projected Relativistic Point-Coupling Approach for Low-Lying Excited States in 24Mg

    NASA Astrophysics Data System (ADS)

    Yao, Jiang-Ming; Meng, Jie; D. Pena, Arteaga; Ring, P.

    2008-10-01

    A full three-dimensional angular momentum projection on top of a triaxial relativistic mean-Geld calculation is implemented for the first time. The underlying Lagrangian is a point coupling model and pairing correlations are taken into account by a monopole force. This method is applied for the low-lying excited states in 24Mg. Good agreement with the experimental data is found for the ground state properties. A minimum in the potential energy surface for the 2+1 state, with β ≃ 0.55,γ ≃ 10°, is used as the basis to investigate the rotational energy spectrum as well as the corresponding B(E2) transition probabilities as compared to the available data.

  6. Axial-vector form factors for the low lying octet baryons in the chiral quark constituent model

    NASA Astrophysics Data System (ADS)

    Dahiya, Harleen; Randhawa, Monika

    2014-10-01

    We have calculated the axial-vector form factors of the low-lying octet baryons (N, Σ, Ξ, and Λ) in the chiral constituent quark model. In particular, we have studied the implications of chiral symmetry breaking and SU(3) symmetry breaking for the singlet (gA0) and nonsinglet (gA3 and gA8) axial-vector coupling constants expressed as combinations of the spin polarizations at zero momentum transfer. The conventional dipole form of parametrization has been used to analyze the Q2 dependence of the axial-vector form factors [GA0(Q2), GA3(Q2), and GA8(Q2)]. The total strange singlet and nonsinglet contents [Gs0(Q2), Gs3(Q2), and Gs8(Q2)] of the nucleon determining the strange quark contribution to the nucleon spin (Δs) have also been discussed.

  7. Dissociation potential curves of low-lying states in transition metal hydrides. 3. Hydrides of groups 6 and 7.

    PubMed

    Koseki, Shiro; Matsushita, Takeshi; Gordon, Mark S

    2006-02-23

    The dissociation curves of low-lying spin-mixed states in monohydrides of groups 6 and 7 were calculated by using an effective core potential (ECP) approach. This approach is based on the multiconfiguration self-consistent field (MCSCF) method, followed by first-order configuration interaction (FOCI) calculations, in which the method employs an ECP basis set proposed by Stevens and co-workers (SBKJC) augmented by a set of polarization functions. Spin-orbit coupling (SOC) effects are estimated within the one-electron approximation by using effective nuclear charges, since SOC splittings obtained with the full Breit-Pauli Hamitonian are underestimated when ECP basis sets are used. The ground states of group 6 hydrides have Omega = (1)/(2)(X(6)Sigma(+)(1/2)), where Omega is the z component of the total angular momentum quantum number. Although the ground states of group 7 hydrides have Omega = 0(+), their main adiabatic components are different; the ground state in MnH originates from the lowest (7)Sigma(+), while in TcH and ReH the main component of the ground state is the lowest (5)Sigma(+). The present paper reports a comprehensive set of theoretical results including the dissociation energies, equilibrium distances, electronic transition energies, harmonic frequencies, anharmonicities, and rotational constants for several low-lying spin-mixed states in these hydrides. Transition dipole moments were also computed among the spin-mixed states and large peak positions of electronic transitions are suggested theoretically for these hydrides. The periodic trends of physical properties of metal hydrides are discussed, based on the results reported in this and other recent studies.

  8. Low-lying electronic states of M(3)O(9)(-) and M(3)O(9)(2-) (M = Mo, W).

    PubMed

    Li, Shenggang; Dixon, David A

    2007-11-01

    Multiple low-lying electronic states of M(3)O(9)(-) and M(3)O(9)(2-) (M = Mo, W) arise from the occupation of the near-degenerate low-lying virtual orbitals in the neutral clusters. We used density functional theory (DFT) and coupled cluster theory (CCSD(T)) with correlation consistent basis sets to study the structures and energetics of the electronic states of these anions. The adiabatic and vertical electron detachment energies (ADEs and VDEs) of the anionic clusters were calculated with 27 exchange-correlation functionals including one local spin density approximation functional, 13 generalized gradient approximation (GGA) functionals, and 13 hybrid GGA functionals, as well as the CCSD(T) method. For M(3)O(9)(-), CCSD(T) and nearly all of the DFT exchange-correlation functionals studied predict the (2)A(1) state arising from the Jahn-Teller distortion due to singly occupying the degenerate e' orbital to be lower in energy than the (2)A(1)' state arising from singly occupying the nondegenerate a(1)' orbital. For W(3)O(9)(-), the (2)A(1) state was predicted to have essentially the same energy as the (2)A(1)' state at the CCSD(T) level with core-valence correlation corrections included and to be higher in energy or essentially isoenergetic with most DFT methods. The calculated VDEs from the CCSD(T) method are in reasonable agreement with the experimental values for both electronic states if estimates for the corrections due to basis set incompleteness are included. For M(3)O(9)(2-), the singlet state arising from doubly occupying the nondegenerate a(1)' orbital was predicted to be the most stable state for both M = Mo and W. However, whereas M(3)O(9)(2-) was predicted to be less stable than M(3)O(9)(-), W(3)O(9)(2-) was predicted to be more stable than W(3)O(9)(-).

  9. From days to decades: numerical modelling of freshwater lens response to climate change stressors on small low-lying islands

    NASA Astrophysics Data System (ADS)

    Holding, S.; Allen, D. M.

    2015-02-01

    Freshwater lenses on small islands are vulnerable to many climate change-related stressors, which can act over relatively long time periods, on the order of decades (e.g., sea level rise, changes in recharge), or short time periods, such as days (storm surge overwash). This study evaluates the response of the freshwater lens on a small low-lying island to various stressors. To account for the varying temporal and spatial scales of the stressors, two different density-dependent flow and solute transport codes are used: SEAWAT (saturated) and HydroGeoSphere (unsaturated/saturated). The study site is Andros Island in the Bahamas, which is characteristic of other low-lying carbonate islands in the Caribbean and Pacific regions. In addition to projected sea level rise and reduced recharge under future climate change, Andros Island experienced a storm surge overwash event during Hurricane Francis in 2004, which contaminated the main wellfield. Simulations of reduced recharge result in a greater loss of freshwater lens volume (up to 19%), while sea level rise contributes a lower volume loss (up to 5%) due to the flux-controlled conceptualization of Andros Island, which limits the impact of sea level rise. Reduced recharge and sea level rise were simulated as incremental instantaneous shifts. The lens responds relatively quickly to these stressors, within 0.5 to 3 years, with response time increasing as the magnitude of the stressor increases. Simulations of the storm surge overwash indicate that the freshwater lens recovers over time; however, prompt remedial action can restore the lens to potable concentrations up to 1 month sooner.

  10. Accessing a low-lying bound electronic state of the alkali oxides, LiO and NaO, using laser induced fluorescence

    NASA Astrophysics Data System (ADS)

    Pugh, J. V.; Shen, K. K.; Winstead, C. B.; Gole, J. L.

    1996-01-01

    The first laser based probe for the sodium and lithium monoxides is established. The Li(Na)+N 2O reactions studied in a multiple collision entrainment mode produce the LiO and NaO ground X 2Π and low-lying monoxide excited states. In contrast to the alkali halides, laser induced excitation spectroscopy confirms that the LiO and NaO B 2Π states, counter to recent predictions, are located at energies well below the ground state dissociation asymptote and, as predicted, possess significant binding energies. An assignment of the laser induced excitation spectra (LIF) for the B 2Π-X 2Π transitions of LiO in the region 3940-4300 Å is based on a direct correlation with the observed chemiluminescence (CL) from the lowest level of the LiO B 2Π state ( ˜4000-7000 Å) and high quality ab initio calculations for the ground state. The self-consistent assignment of the observed LIF and CL spectra makes use of the complimentary extended progressions in the X 2Π (CL) and B 2Π (LIF) vibrational level structure which results from the significant shift of the B 2Π excited state potential relative to that of the ground state. The experimental data are consistent with an excited state vibrational frequency separation of order 130 cm -1, and T e( B2Π) ≈ 26078 ± 800 cm-1. The latter value, in correlation with the ground state dissociation energy of LiO, suggests a B 2Π excited state dissociation energy well in excess of 2000 cm -1. The radiative lifetimes of the lowest levels of the LiO B 2Π state, isoergic with the highest levels of the LiO ground state, are determined to be in excess of 600 ns. The corresponding NaO excitation spectra in the range 6680-7250 Å also correlate well with ab initio calculations for the ground electronic state of NaO. Within this study, we provide optical signatures which one might consider to monitor LiO or NaO in process streams. In correlation with the observed chemiluminescence from B 2Π states of the higher alkali oxides KO, RbO, and

  11. Superconducting magnetic quadrupole

    SciTech Connect

    Kim, J.W.; Shepard, K.W.; Nolen, J.A.

    1995-08-01

    A design was developed for a 350 T/m, 2.6-cm clear aperture superconducting quadrupole focussing element for use in a very low q/m superconducting linac as discussed below. The quadrupole incorporates holmium pole tips, and a rectangular-section winding using standard commercially-available Nb-Ti wire. The magnet was modeled numerically using both 2D and 3D codes, as a basis for numerical ray tracing using the quadrupole as a linac element. Components for a prototype singlet are being procured during FY 1995.

  12. Systematics of low-lying electric dipole excitations in the A{approx_equal}130{endash}200 mass region

    SciTech Connect

    Fransen, C.; von Brentano, P.; Herzberg, R.; Pietralla, N.; Zilges, A.; Beck, O.; Eckert, T.; Kneissl, U.; Maser, H.; Nord, A.; Pitz, H.H.; Zilges, A.

    1998-01-01

    The data from numerous high resolution photon scattering experiments allow an extensive survey of the lowest electric dipole excitations in the A{approx_equal}130{endash}200 mass region. In this mass region one can find spherical as well as transitional and strongly quadrupole deformed nuclei. The measured absolute E1 strengths are typically of the order of several milli Weisskopf units and exhibit in general a smooth variation with mass number. {copyright} {ital 1998} {ital The American Physical Society}

  13. Vibrational stability of NLC linac and final focus components

    SciTech Connect

    F. Le Pimpec et al.

    2003-02-06

    Vertical vibration of linac components (accelerating structures, girders and quadrupoles) in the NLC has been studied experimentally and analytically. Effects such as structural resonances and vibration caused by cooling water both in accelerating structures and quadrupoles have been considered. Experimental data has been compared with analytical predictions and simulations using ANSYS. A design, incorporating the proper decoupling of structure vibrations from the linac quadrupoles, is being pursued.

  14. Vibrational Stability of NLC Linac and Final Focus Components

    SciTech Connect

    Le Pimpec, Frederic

    2002-09-25

    Vertical vibration of linac components (accelerating structures, girders and quadrupoles) in the NLC has been studied experimentally and analytically. Effects such as structural resonances and vibration caused by cooling water both in accelerating structure and quadrupoles have been considered. Experimental data has been compared with analytical predictions and simulations using ANSYS. Design to properly decouple the structure vibrations from the linac quadrupoles is being pursued.

  15. A quantitative evaluation method of flood risks in low-lying areas associated with increase of heavy rainfall in Japan

    NASA Astrophysics Data System (ADS)

    Minakawa, H.; Masumoto, T.

    2012-12-01

    An increase in flood risk, especially in low-lying areas, is predicted as a consequence of global climate change or other causes. Immediate measures such as strengthening of drainage capacity are needed to minimize the damage caused by more-frequent flooding. Typically, drainage pump capacities of in paddy areas are planned by using a result of drainage analysis with design rainfall (e.g. 3-day rainfall amount with a 10-year return period). However, the result depends on a hyetograph of input rainfall even if a total amount of rainfall is equal, and the flood risk may be different with rainfall patterns. Therefore, it is important to assume various patterns of heavy rainfall for flood risk assessment. On the other hand, a rainfall synthesis simulation is useful to generate many patterns of rainfall data for flood studies. We previously proposed a rainfall simulation method called diurnal rainfall pattern generator which can generate short-time step rainfall and internal pattern of them. This study discusses a quantitative evaluation method for detecting a relationship between flood damage risk and heavy rainfall scale by using the diurnal rainfall pattern generator. In addition, we also approached an estimation of flood damage which focused on rice yield. Our study area was in the Kaga three-lagoon basin in Ishikawa Prefecture, Japan. There are two lagoons in the study area, and the low-lying paddy areas extend over about 4,000 ha in the lower reaches of the basin. First, we developed a drainage analysis model that incorporates kinematic and diffusive runoff models for calculating water level on channels and paddies. Next, the heavy rainfall data for drainage analysis were generated. Here, the 3-day rainfalls amounts with 9 kinds of different return periods (2-, 3-, 5-, 8-, 10-, 15-, 50-, 100-, and 200-year) were derived, and three hundred hyetograph patterns were generated for each rainfall amount by using the diurnal rainfall pattern generator. Finally, all data

  16. Low-Lying Electronic States of M₃O₉- and M₃O₉²- (M = Mo, W).

    SciTech Connect

    Li, Shenggang; Dixon, David A.

    2007-11-01

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. Multiple low-lying electronic states of M₃O₉- and M₃O₉²- (M = Mo, W) arise from the occupation of the near-degenerate low-lying virtual orbitals in the neutral clusters. We used density functional theory (DFT) and coupled cluster theory (CCSD(T)) with correlation consistent basis sets to study the structures and energetics of the electronic states of these anions. The adiabatic and vertical electron detachment energies (ADEs and VDEs) of the anionic clusters were calculated with 27 exchange-correlation functionals including one local spin density approximation functional, 13 generalized gradient approximation (GGA) functionals, and 13 hybrid GGA functionals, as well as the CCSD(T) method. For Mo₃O₉-, CCSD(T) and nearly all of the DFT exchange-correlation functionals studied predict the 2A1 state arising from the Jahn-Teller distortion due to singly occupying the degenerate e' orbital to be lower in energy than the ²A₁' state arising from singly occupying the nondegenerate a₁' orbital. For W₃O₉-, the ²A₁' state was predicted to have essentially the same energy as the ²A₁' state at the CCSD(T) level with core-valence correlation corrections included and to be higher in energy or essentially isoenergetic with most DFT methods. The calculated VDEs from the CCSD(T) method are in reasonable agreement with the experimental values for both electronic states if estimates for the corrections due to basis set incompleteness are included. For M₃O₉²-, the singlet state arising from doubly occupying the nondegenerate a₁' orbital was predicted to be the most stable state for both M ) Mo and W. However, whereas Mo₃O₉²- was predicted to be less stable than

  17. Increasing Risks to China's Coastal Cities with Its Expansion to Low-lying Seaward under Rising Sea level

    NASA Astrophysics Data System (ADS)

    Kang, Jing; Cheng, Xiao

    2014-05-01

    Global sea level rise has certainly accelerated through the 21st and far beyond the previous projections and will continue to rise, while the frequencies and strength of extreme events such like flood and storm will increase due to global warming. Coastal cities where always be with densely population and accumulated social wealth will be under enormous affects. Using Landsat TM/ETM+ satellite images (1990, 2010) to extract urban built-up area, 17 China's developed coastal cities, which account for only 1.2% of total land area but boast 18.3% of urban population and nearly 19.6% of GDP in 2010, are spotted a 550% increase of urban land from 1990 to 2010. Shuttle Radar Topography Mission (SRTM) with 90m resolution data were used to calculate average elevation of extracted urban area. Then we found that these cities are all expanding seaward, occupying the most vulnerable neighborhoods, often in low-lying areas, alongside waterways prone to flooding. 11 cities show a reducing trend of mean elevations with the total average of more than 3 meters. Particularly, Shanghai, Tianjin and Ningbo in Delta area are most serious with the mean urban elevation less than 5 meters in 2010. The rapid expansion to seawards and accumulation of population and social wealth processed in coastal cities will increase the vulnerability and exposure, which will exacerbated the existing risks of rising sea level or extreme events. Referring to Defense Meteorological Satellite Program (DMSP/OLS) city-lights data and SRTM data, we built the Urban Vulnerability Index (UVI) to do semi-quantitative assessment on vulnerabilities of coastal cities. The UVI case study in GuangZhou showed the most vulnerability region concentrated at the low-lying south area where is with the much higher relative South Sea level than other sea area of China. With relative sea level rise of 1-1.5 m by 2100 and increased frequency of extreme sea level due to cyclone propagation, and weak urban drain-off system, Chinese

  18. Nucleosynthesis of 92Nb and the relevance of the low-lying isomer at 135.5 keV

    NASA Astrophysics Data System (ADS)

    Mohr, Peter

    2016-06-01

    Background: Because of its half-life of about 35 million years, 92Nb is considered as a chronometer for nucleosynthesis events prior to the birth of our sun. The abundance of 92Nb in the early solar system can be derived from meteoritic data. It has to be compared to theoretical estimates for the production of 92Nb to determine the time between the last nucleosynthesis event before the formation of the early solar system. Purpose: The influence of a low-lying short-lived isomer on the nucleosynthesis of 92Nb is analyzed. The thermal coupling between the ground state and the isomer via so-called intermediate states affects the production and survival of 92Nb. Method: The properties of the lowest intermediate state in 92Nb are known from experiment. From the lifetime of the intermediate state and from its decay branchings, the transition rate from the ground state to the isomer and the effective half-life of 92Nb are calculated as functions of the temperature. Results: The coupling between the ground state and the isomer is strong. This leads to thermalization of ground state and isomer in the nucleosynthesis of 92Nb in any explosive production scenario and almost 100% survival of 92Nb in its ground state. However, the strong coupling leads to a temperature-dependent effective half-life of 92Nb which makes the 92Nb survival very sensitive to temperatures as low as about 8 keV, thus turning 92Nb at least partly into a thermometer. Conclusions: The low-lying isomer in 92Nb does not affect the production of 92Nb in explosive scenarios. In retrospect this validates all previous studies where the isomer was not taken into account. However, the dramatic reduction of the effective half-life at temperatures below 10 keV may affect the survival of 92Nb after its synthesis in supernovae, which are the most likely astrophysical sites for the nucleosynthesis of 92Nb.

  19. Ultrafast electron dynamics following outer-valence ionization: The impact of low-lying relaxation satellite states

    NASA Astrophysics Data System (ADS)

    Lünnemann, Siegfried; Kuleff, Alexander I.; Cederbaum, Lorenz S.

    2009-04-01

    Low-lying relaxation satellites give rise to ultrafast electron dynamics following outer-valence ionization of a molecular system. To demonstrate the impact of such satellites, the evolution of the electronic cloud after sudden removal of an electron from the highest occupied molecular orbital (HOMO) of the organic unsaturated nitroso compound 2-nitroso[1,3]oxazolo[5,4-d][1,3]oxazole is traced in real time and space using ab initio methods only. Our results show that the initially created hole charge remains stationary but on top of it the system reacts by an ultrafast π-π ∗ excitation followed by a cyclic excitation-de-excitation process which leads to a redistribution of the charge. The π-π ∗ excitation following the removal of the HOMO electron takes place on a subfemtosecond time scale and the period of the excitation-de-excitation alternations is about 1.4 fs. In real space the processes of excitation and de-excitation represent ultrafast delocalization and localization of the charge. The results are analyzed by simple two- and three-state models.

  20. Operational flood control of a low-lying delta system using large time step Model Predictive Control

    NASA Astrophysics Data System (ADS)

    Tian, Xin; van Overloop, Peter-Jules; Negenborn, Rudy R.; van de Giesen, Nick

    2015-01-01

    The safety of low-lying deltas is threatened not only by riverine flooding but by storm-induced coastal flooding as well. For the purpose of flood control, these deltas are mostly protected in a man-made environment, where dikes, dams and other adjustable infrastructures, such as gates, barriers and pumps are widely constructed. Instead of always reinforcing and heightening these structures, it is worth considering making the most of the existing infrastructure to reduce the damage and manage the delta in an operational and overall way. In this study, an advanced real-time control approach, Model Predictive Control, is proposed to operate these structures in the Dutch delta system (the Rhine-Meuse delta). The application covers non-linearity in the dynamic behavior of the water system and the structures. To deal with the non-linearity, a linearization scheme is applied which directly uses the gate height instead of the structure flow as the control variable. Given the fact that MPC needs to compute control actions in real-time, we address issues regarding computational time. A new large time step scheme is proposed in order to save computation time, in which different control variables can have different control time steps. Simulation experiments demonstrate that Model Predictive Control with the large time step setting is able to control a delta system better and much more efficiently than the conventional operational schemes.

  1. Ab initio calculations of the electronic structure of the low-lying states for the ultracold LiYb molecule

    SciTech Connect

    Tohme, Samir N.; Korek, Mahmoud E-mail: fkorek@yahoo.com; Awad, Ramadan

    2015-03-21

    Ab initio techniques have been applied to investigate the electronic structure of the LiYb molecule. The potential energy curves have been computed in the Born–Oppenheimer approximation for the ground and 29 low-lying doublet and quartet excited electronic states. Complete active space self-consistent field, multi-reference configuration interaction, and Rayleigh Schrödinger perturbation theory to second order calculations have been utilized to investigate these states. The spectroscopic constants, ω{sub e}, R{sub e}, B{sub e}, …, and the static dipole moment, μ, have been investigated by using the two different techniques of calculation with five different types of basis. The eigenvalues, E{sub v}, the rotational constant, B{sub v}, the centrifugal distortion constant, D{sub v}, and the abscissas of the turning points, R{sub min} and R{sub max}, have been calculated by using the canonical functions approach. The comparison between the values of the present work, calculated by different techniques, and those available in the literature for several electronic states shows a very good agreement. Twenty-one new electronic states have been studied here for the first time.

  2. Saltwater contamination in the managed low-lying farmland of the Venice coast, Italy: An assessment of vulnerability.

    PubMed

    Da Lio, Cristina; Carol, Eleonora; Kruse, Eduardo; Teatini, Pietro; Tosi, Luigi

    2015-11-15

    The original morphology and hydrogeology of many low-lying coastlands worldwide have been significantly modified over the last century through river diversion, embankment built-up, and large-scale land reclamation projects. This led to a progressive shifting of the groundwater-surficial water exchanges from naturally to anthropogenically driven. In this human-influenced hydrologic landscape, the saltwater contamination usually jeopardizes the soil productivity. In the coastland south of Venice (Italy), several well log measurements, chemical and isotope analyses have been performed over the last decade to characterize the occurrence of the salt contamination. The processing of this huge dataset highlights a permanent variously-shaped saline contamination up to 20km inland, with different conditions in relation with the various geomorphological features of the area. The results point out the important role of the land reclamation in shaping the present-day salt contamination and reveal the contribution of precipitation, river discharge, lagoon and sea water to the shallow groundwater in the various coastal sectors. Moreover, an original vulnerability map to salt contamination in relation to the farmland productivity has been developed taking into account the electrical conductivity of the upper aquifer in the worst condition, the ground elevation, and the distance from salt and fresh surface water sources. Finally, the study allows highlighting the limit of traditional investigations in monitoring saltwater contamination at the regional scale in managed Holocene coastal environments. Possible improvements are outlined.

  3. Correcting Quadrupole Roll in Magnetic Lenses with Skew Quadrupoles

    SciTech Connect

    Walstrom, Peter Lowell

    2014-11-10

    Quadrupole rolls (i.e. rotation around the magnet axis) are known to be a significant source of image blurring in magnetic quadrupole lenses. These rolls may be caused by errors in mechanical mounting of quadrupoles, by uneven radiation-induced demagnetization of permanent-magnet quadrupoles, etc. Here a four-quadrupole ×10 lens with so-called ”Russian” or A -B B-A symmetry is used as a model problem. Existing SLAC 1/2 in. bore high-gradient quadrupoles are used in the design. The dominant quadrupole roll effect is changes in the first-order part of the transfer map (the R matrix) from the object to the image plane (Note effects on the R matrix can be of first order in rotation angle for some R-matrix elements and second order in rotation angle for other elements, as shown below). It is possible to correct roll-induced image blur by mechanically adjusting the roll angle of one or more of the quadrupoles. Usually, rotation of one quadrupole is sufficient to correct most of the combined effect of rolls in all four quadrupoles. There are drawbacks to this approach, however, since mechanical roll correction requires multiple entries into experimental area to make the adjustments, which are made according to their effect on images. An alternative is to use a single electromagnetic skew quadrupole corrector placed either between two of the quadrupoles or after the fourth quadrupole (so-called “non-local” correction). The basic feasibility of skew quadrupole correction of quadrupole roll effects is demonstrated here. Rolls of the third lens quadrupole of up to about 1 milliradian can be corrected with a 15 cm long skew quadrupole with a gradient of up to 1 T/m. Since the effect of rolls of the remaining three lens quadrupoles are lower, a weaker skew quadrupole can be used to correct them. Non-local correction of quadrupole roll effects by skew quadrupoles is shown to be about one-half as effective as local correction (i.e. rotating individual quadrupoles to zero

  4. MRCI study of the spectroscopic parameters and transition properties of the 36 low-lying electronic states of the B2 molecule

    NASA Astrophysics Data System (ADS)

    Xing, Wei; Shi, Deheng; Sun, Jinfeng; Zhu, Zunlue

    2017-10-01

    This paper studied the spectroscopic and transition properties of 36 low-lying states, which came from the first two dissociation limits of B2 molecule. The potential energy curves were calculated with the complete active space self-consistent field (CASSCF) method, which was followed by the internally contracted multireference configuration interaction (icMRCI) plus Davidson modification (icMRCI + Q) approach. Of these 36 states, the 25Σu-, 15Σu+, 25Πu, and 15Δu states were repulsive; the B3Δu, E3Σu+, f1Σu-, g1Πg, 23Πu, 33Σg-, 33Πu, 15Πg, and 33Σu+ states had double wells; the B3Δu, E3Σu+, G3Σu+, f1Σu-, g1Πg, 33Σg-, 23Πu, 33Πu, 15Πg, 25Πg, 25Σg-, and 33Σu+ states had one barrier; the 25Σg- state and the second wells of B3Δu, E3Σu+, 15Πg, f1Σu-, g1Πg, and 23Πu states were weakly bound; and the 25Σg- state had no vibrational levels. The avoided crossings existed between the B3Δu and 23Δu states, the E3Σu+ and G3Σu+ states, the G3Σu+ and 33Σu+ states, the 33Σu+ and 43Σu+ states, the 23Πu and 33Πu states, the g1Πg and 21Πg states, the 23Σg- and 33Σg- states, the 15Πg and 25Πg states, the 25Πg and 35Πg states, the 25Σg- and 35Σg- states, as well as the F3Πg and 33Πg states. Core-valence correlation and scalar relativistic corrections were taken into account. The extrapolation to the complete basis set limit was done. The spectroscopic parameters and vibrational properties were obtained. The transition dipole moments were calculated. Franck-Condon factors of some transitions were evaluated. The spin-orbit coupling (SOC) effect on the spectroscopic parameters and vibrational properties is tiny and sometimes even can be negligible. The results determined in this paper can provide some powerful guidelines to observe these states, in particular the states which have not been studied in the experiment.

  5. Electronic spectra and excited state dynamics of pentafluorophenol: Effects of low-lying πσ∗ states

    NASA Astrophysics Data System (ADS)

    Karmakar, Shreetama; Mukhopadhyay, Deb Pratim; Chakraborty, Tapas

    2015-05-01

    Multiple fluorine atom substitution effect on photophysics of an aromatic chromophore has been investigated using phenol as the reference system. It has been noticed that the discrete vibronic structure of the S1←S0 absorption system of phenol vapor is completely washed out for pentafluorophenol (PFP), and the latter also shows very large Stokes shift in the fluorescence spectrum. For excitations beyond S1 origin, the emission yield of PFP is reduced sharply with increase in excess vibronic energy. However, in a collisional environment like liquid hydrocarbon, the underlying dynamical process that drives the non-radiative decay is hindered drastically. Electronic structure theory predicts a number of low-lying dark electronic states of πσ∗ character in the vicinity of the lowest valence ππ∗ state of this molecule. Tentatively, we have attributed the excitation energy dependent non-radiative decay of the molecule observed only in the gas phase to an interplay between the lowest ππ∗ and a nearby dissociative πσ∗ state. Measurements in different liquids reveal that some of the dark excited states light up with appreciable intensity only in protic liquids like methanol and water due to hydrogen bonding between solute and solvents. Electronic structure theory methods indeed predict that for PFP-(H2O)n clusters (n = 1-11), intensities of a number of πσ∗ states are enhanced with increase in cluster size. In contrast with emitting behavior of the molecule in the gas phase and solutions of nonpolar and polar aprotic liquids, the fluorescence is completely switched off in polar protic liquids. This behavior is a chemically significant manifestation of perfluoro effect, because a very opposite effect occurs in the case of unsubstituted phenol for which fluorescence yield undergoes a very large enhancement in protic liquids. Several dynamical mechanisms have been suggested to interpret the observed photophysical behavior.

  6. Seawater-flooding events and impact on freshwater lenses of low-lying islands: Controlling factors, basic management and mitigation

    NASA Astrophysics Data System (ADS)

    Gingerich, Stephen B.; Voss, Clifford I.; Johnson, Adam G.

    2017-08-01

    An unprecedented set of hydrologic observations was collected after the Dec 2008 seawater-flooding event on Roi-Namur, Kwajalein Atoll, Republic of the Marshall Islands. By two days after the seawater flooding that occurred at the beginning of dry season, the observed salinity of water withdrawn by the island's main skimming well increased to 100% seawater concentration, but by ten days later already decreased to only 10-20% of seawater fraction. However, the damaging impact on the potability of the groundwater supply (when pumped water had concentrations above 1% seawater fraction) lasted 22 months longer. The data collected make possible analyses of the hydrologic factors that control recovery and management of the groundwater-supply quality on Roi-Namur and on similar low-lying islands. With the observed data as a guide, three-dimensional numerical-model simulation analyses reveal how recovery is controlled by the island's hydrology. These also allow evaluation of the efficacy of basic water-quality management/mitigation alternatives and elucidate how groundwater withdrawal and timing of the seawater-flooding event affect the length of recovery. Simulations show that, as might be expected, by adding surplus captured rainwater as artificial recharge, the freshwater-lens recovery period (after which potable groundwater may again be produced) can be shortened, with groundwater salinity remaining lower even during the dry season, a period during which no artificial recharge is applied. Simulations also show that the recovery period is not lengthened appreciably by groundwater withdrawals during recovery. Simulations further show that had the flooding event occurred at the start of the wet season, the recovery period would have been about 25% (5.5 months) shorter than actually occurred during the monitored flood that occurred at the dry-season start. Finally, analyses show that artificial recharge improves freshwater-lens water quality, making possible longer use of

  7. Search for global-minimum geometries of medium-sized germanium clusters. II. Motif-based low-lying clusters Ge21-Ge29

    NASA Astrophysics Data System (ADS)

    Yoo, S.; Zeng, X. C.

    2006-05-01

    We performed a constrained search for the geometries of low-lying neutral germanium clusters GeN in the size range of 21⩽N⩽29. The basin-hopping global optimization method is employed for the search. The potential-energy surface is computed based on the plane-wave pseudopotential density functional theory. A new series of low-lying clusters is found on the basis of several generic structural motifs identified previously for silicon clusters [S. Yoo and X. C. Zeng, J. Chem. Phys. 124, 054304 (2006)] as well as for smaller-sized germanium clusters [S. Bulusu et al., J. Chem. Phys. 122, 164305 (2005)]. Among the generic motifs examined, we found that two motifs stand out in producing most low-lying clusters, namely, the six/nine motif, a puckered-hexagonal-ring Ge6 unit attached to a tricapped trigonal prism Ge9, and the six/ten motif, a puckered-hexagonal-ring Ge6 unit attached to a bicapped antiprism Ge10. The low-lying clusters obtained are all prolate in shape and their energies are appreciably lower than the near-spherical low-energy clusters. This result is consistent with the ion-mobility measurement in that medium-sized germanium clusters detected are all prolate in shape until the size N ˜65.

  8. Magnetic Resonance Imaging Analysis of Peroneal Tendon Pathology Associated With Low-Lying Peroneus Brevis Muscle Belly: A Case-Control Study.

    PubMed

    Highlander, Peter; Pearson, Kyle T; Burns, Patrick

    2015-10-01

    Low-lying peroneus brevis tendon muscle belly has been speculated to be an associated factor with symptomatic peroneal tendon pathology. Multiple studies have analyzed normal and anomalous anatomy associated with peroneal tendon pathology; however, no study has confirmed the clinical association between peroneal tendon pathology and low-lying peroneus brevis muscle belly. To identify the correlation of low-lying peroneus brevis muscle belly with peroneal tendon pathology. Case-control study; Level of evidence 3. The level of peroneus brevis muscle belly was compared between patients with symptomatic peroneal tendon pathology (experimental group) and asymptomatic individuals with otherwise normal lateral ankle using magnetic resonance images. Of the 32 consecutive patients with symptomatic peroneal tendon pathology, 28 (87.5%) demonstrated peroneus brevis muscle distal to the fibular groove while 53.8% of control patients demonstrated such findings (P = .022). The most common diagnosis associated with peroneal tendon pathology was ankle instability and osteochondral defect of the talus or tibial plafond. Peroneal tendon pathology in isolation was less common. Peroneal tendon pathology is often associated with lateral ankle instability and osteochondral defects of the ankle joint. Low-lying peroneus brevis muscle belly may be a common anatomic variant, but in the setting of instability it can become a source of pain and pathology secondary to overcrowding. Diagnostic, level III: Case-control study. © 2015 The Author(s).

  9. Low-Lying Energy Isomers and Global Minima of Aqueous Nanoclusters: Structures and Spectroscopic Features of the Pentagonal Dodecahedron (H2O)20 and (H3O)+(H2O)20

    SciTech Connect

    Xantheas, Sotiris S.

    2012-08-01

    We rely on a hierarchy of methods to identify the low-lying isomers for the pentagonal dodecahedron (H2O)20 and the H3O+(H2O)20 clusters. Initial screening of isomers was performed with classical potentials [TIP4P, TTM2-F, TTM2.1-F for (H2O)20 and ASP for H3O+(H2O)20] and the networks obtained with those potentials were subsequently reoptimized at the DFT (B3LYP) and MP2 levels of theory. For the pentagonal dodecahedron (H2O)20 it was found that DFT (B3LYP) and MP2 produced the same global minimum. However, this was not the case for the H3O+(H2O)20 cluster, for which MP2 produced a different network for the global minimum when compared to DFT (B3LYP). All low-lying minima of H3O+(H2O)20 correspond to hydrogen bonding networks having 9 ''free'' OH bonds and the hydronium ion on the surface of the cluster. The fact that DFT (B3LYP) and MP2 produce different results and issues related to the use of a smaller basis set, explains the discrepancy between the current results and the structure previously suggested [Science 304, 1137 (2004)] for the global minimum of the H3O+(H2O)20 cluster. Additionally, the IR spectra of the MP2 global minimum are closer to the experimentally measured ones than the spectra of the previously suggested DFT global minimum. The latter exhibit additional bands in the most red-shifted region of the OH stretching vibrations (corresponding to the ''fingerprint'' of the underlying hydrogen bonding network), which are absent from both the experimental as well as the spectra of the new structure suggested for the global minimum of this cluster.

  10. Consistent quadrupole-octupole collective model

    NASA Astrophysics Data System (ADS)

    Dobrowolski, A.; Mazurek, K.; Góźdź, A.

    2016-11-01

    Within this work we present a consistent approach to quadrupole-octupole collective vibrations coupled with the rotational motion. A realistic collective Hamiltonian with variable mass-parameter tensor and potential obtained through the macroscopic-microscopic Strutinsky-like method with particle-number-projected BCS (Bardeen-Cooper-Schrieffer) approach in full vibrational and rotational, nine-dimensional collective space is diagonalized in the basis of projected harmonic oscillator eigensolutions. This orthogonal basis of zero-, one-, two-, and three-phonon oscillator-like functions in vibrational part, coupled with the corresponding Wigner function is, in addition, symmetrized with respect to the so-called symmetrization group, appropriate to the collective space of the model. In the present model it is D4 group acting in the body-fixed frame. This symmetrization procedure is applied in order to provide the uniqueness of the Hamiltonian eigensolutions with respect to the laboratory coordinate system. The symmetrization is obtained using the projection onto the irreducible representation technique. The model generates the quadrupole ground-state spectrum as well as the lowest negative-parity spectrum in 156Gd nucleus. The interband and intraband B (E 1 ) and B (E 2 ) reduced transition probabilities are also calculated within those bands and compared with the recent experimental results for this nucleus. Such a collective approach is helpful in searching for the fingerprints of the possible high-rank symmetries (e.g., octahedral and tetrahedral) in nuclear collective bands.

  11. Seawater-flooding events and impact on freshwater lenses of low-lying islands: Controlling factors, basic management and mitigation

    USGS Publications Warehouse

    Gingerich, Stephen B.; Voss, Clifford I.; Johnson, Adam G.

    2017-01-01

    An unprecedented set of hydrologic observations was collected after the Dec 2008 seawater-flooding event on Roi-Namur, Kwajalein Atoll, Republic of the Marshall Islands. By two days after the seawater flooding that occurred at the beginning of dry season, the observed salinity of water withdrawn by the island’s main skimming well increased to 100% seawater concentration, but by ten days later already decreased to only 10–20% of seawater fraction. However, the damaging impact on the potability of the groundwater supply (when pumped water had concentrations above 1% seawater fraction) lasted 22 months longer. The data collected make possible analyses of the hydrologic factors that control recovery and management of the groundwater-supply quality on Roi-Namur and on similar low-lying islands.With the observed data as a guide, three-dimensional numerical-model simulation analyses reveal how recovery is controlled by the island’s hydrology. These also allow evaluation of the efficacy of basic water-quality management/mitigation alternatives and elucidate how groundwater withdrawal and timing of the seawater-flooding event affect the length of recovery. Simulations show that, as might be expected, by adding surplus captured rainwater as artificial recharge, the freshwater-lens recovery period (after which potable groundwater may again be produced) can be shortened, with groundwater salinity remaining lower even during the dry season, a period during which no artificial recharge is applied. Simulations also show that the recovery period is not lengthened appreciably by groundwater withdrawals during recovery. Simulations further show that had the flooding event occurred at the start of the wet season, the recovery period would have been about 25% (5.5 months) shorter than actually occurred during the monitored flood that occurred at the dry-season start. Finally, analyses show that artificial recharge improves freshwater-lens water quality, making possible longer

  12. Coastline evolution of Portuguese low-lying sandy coast in the last 50 years: an integrated approach

    NASA Astrophysics Data System (ADS)

    Ponte Lira, Cristina; Nobre Silva, Ana; Taborda, Rui; Freire de Andrade, Cesar

    2016-06-01

    Regional/national-scale information on coastline rates of change and trends is extremely valuable, but these studies are scarce. A widely accepted standardized methodology for analysing long-term coastline change has been difficult to achieve, but it is essential to conduct an integrated and holistic approach to coastline evolution and hence support coastal management actions. Additionally, databases providing knowledge on coastline evolution are of key importance to support both coastal management experts and users.The main objective of this work is to present the first systematic, national-scale and consistent long-term coastline evolution data of Portuguese mainland low-lying sandy coasts.The methodology used quantifies coastline evolution using a unique and robust coastline indicator (the foredune toe), which is independent of short-term changes.The dataset presented comprises (1) two polyline sets, mapping the 1958 and 2010 sandy beach-dune system coastline, both optimized for working at 1 : 50 000 scale or smaller; (2) one polyline set representing long-term change rates between 1958 and 2010, each estimated at 250 m; and (3) a table with minimum, maximum and mean of evolution rates for sandy beach-dune system coastline. All science data produced here are openly accessible at https://doi.pangaea.de/10.1594/PANGAEA.859136 and can be used in other studies.Results show beach erosion as the dominant trend, with a mean change rate of -0.24 ± 0.01 m year-1 for all mainland Portuguese beach-dune systems. Although erosion is dominant, this evolution is variable in signal and magnitude in different coastal sediment cells and also within each cell. The most relevant beach erosion issues were found in the coastal stretches of Espinho-Torreira and Costa Nova-Praia de Mira, Cova da Gala-Leirosa, and Cova do Vapor-Costa da Caparica. The coastal segments Minho River-Nazaré and Costa da Caparica

  13. Electronic spectra and excited state dynamics of pentafluorophenol: Effects of low-lying πσ{sup ∗} states

    SciTech Connect

    Karmakar, Shreetama; Mukhopadhyay, Deb Pratim; Chakraborty, Tapas

    2015-05-14

    Multiple fluorine atom substitution effect on photophysics of an aromatic chromophore has been investigated using phenol as the reference system. It has been noticed that the discrete vibronic structure of the S{sub 1}←S{sub 0} absorption system of phenol vapor is completely washed out for pentafluorophenol (PFP), and the latter also shows very large Stokes shift in the fluorescence spectrum. For excitations beyond S{sub 1} origin, the emission yield of PFP is reduced sharply with increase in excess vibronic energy. However, in a collisional environment like liquid hydrocarbon, the underlying dynamical process that drives the non-radiative decay is hindered drastically. Electronic structure theory predicts a number of low-lying dark electronic states of πσ{sup ∗} character in the vicinity of the lowest valence ππ{sup ∗} state of this molecule. Tentatively, we have attributed the excitation energy dependent non-radiative decay of the molecule observed only in the gas phase to an interplay between the lowest ππ{sup ∗} and a nearby dissociative πσ{sup ∗} state. Measurements in different liquids reveal that some of the dark excited states light up with appreciable intensity only in protic liquids like methanol and water due to hydrogen bonding between solute and solvents. Electronic structure theory methods indeed predict that for PFP-(H{sub 2}O){sub n} clusters (n = 1-11), intensities of a number of πσ{sup ∗} states are enhanced with increase in cluster size. In contrast with emitting behavior of the molecule in the gas phase and solutions of nonpolar and polar aprotic liquids, the fluorescence is completely switched off in polar protic liquids. This behavior is a chemically significant manifestation of perfluoro effect, because a very opposite effect occurs in the case of unsubstituted phenol for which fluorescence yield undergoes a very large enhancement in protic liquids. Several dynamical mechanisms have been suggested to interpret the

  14. Quadrupole contribution to the third-order optical activity spectroscopy

    NASA Astrophysics Data System (ADS)

    Choi, Jun-Ho; Cho, Minhaeng

    2007-07-01

    Time-resolved nonlinear optical activity measurement spectroscopy can be a useful tool for studying biomolecular and chemical reaction dynamics of chiral molecules. Only recently, the two-dimensional (2D) circularly polarized photon echo (CP-PE) spectroscopy of polypeptides and a photosynthetic light-harvesting complex were discussed, where the beam configuration was specifically controlled in such a way to eliminate the quadrupole contribution to the CP-PE signal. In this paper, we generalize the CP-PE spectroscopy by including the transition quadrupole contributions from peptide amide I vibrational transition and chlorophyll electronic transition. By using a density functional theory calculation method, the corresponding amide I vibrational and chlorophyll Qy electronic transition quadrupole tensor elements are determined. Amplitude of nonlinear optical transition pathway involving a quadrupole transition is found to be comparable to those of magnetic dipole terms for two different cases considered, i.e., dipeptides and photosynthetic antenna complex. However, due to the rotational averaging factors, the overall quadrupole contribution is an order of magnitude smaller than the magnetic dipole contribution. This suggests that the conventional 2D photon echo method and experimental scheme can be directly used to measure the 2D CP-PE signal from proteins and molecular complexes and that the 2D CP-PE signal is mainly dictated by the magnetic dipole contribution.

  15. Quadrupole contribution to the third-order optical activity spectroscopy.

    PubMed

    Choi, Jun-Ho; Cho, Minhaeng

    2007-07-14

    Time-resolved nonlinear optical activity measurement spectroscopy can be a useful tool for studying biomolecular and chemical reaction dynamics of chiral molecules. Only recently, the two-dimensional (2D) circularly polarized photon echo (CP-PE) spectroscopy of polypeptides and a photosynthetic light-harvesting complex were discussed, where the beam configuration was specifically controlled in such a way to eliminate the quadrupole contribution to the CP-PE signal. In this paper, we generalize the CP-PE spectroscopy by including the transition quadrupole contributions from peptide amide I vibrational transition and chlorophyll electronic transition. By using a density functional theory calculation method, the corresponding amide I vibrational and chlorophyll Q(y) electronic transition quadrupole tensor elements are determined. Amplitude of nonlinear optical transition pathway involving a quadrupole transition is found to be comparable to those of magnetic dipole terms for two different cases considered, i.e., dipeptides and photosynthetic antenna complex. However, due to the rotational averaging factors, the overall quadrupole contribution is an order of magnitude smaller than the magnetic dipole contribution. This suggests that the conventional 2D photon echo method and experimental scheme can be directly used to measure the 2D CP-PE signal from proteins and molecular complexes and that the 2D CP-PE signal is mainly dictated by the magnetic dipole contribution.

  16. An Approach to Assessing Flood Risk in Low-lying Paddy Areas of Japan considering Economic Damage on Rice

    NASA Astrophysics Data System (ADS)

    Minakawa, H.; Masumoto, T.

    2013-12-01

    constructed in a rice paddy plot, which consisted of two zones, one in which the rice was cultivated as usual with normal water levels, and a flood zone, which was used for submerging rice plants. The flood zone, which was designed to reproduce actual flood disaster conditions in paddy fields, can be filled with water to a depth of 0.3, 0.6 or 0.9 m above ground level, and is divided into two plots, a clean water part and a turbid water part. Thus, the experimental conditions can vary according to 1) the development stage of rice, 2) complete or incomplete submersion, 3) clean or turbid water, and 4) duration of submergence. Finally, the reduction scales were formulated by using the resultant data and it was found that rice is most sensitive to damage during the development stage. Flood risk was evaluated by using calculated water level on each paddy. Here, the averaged duration of inundation to a depth of more than 0.3 m was used as the criteria for flood occurrence. The results indicated that the duration increased with larger heavy rainfall amounts. Furthermore, the damage to rice was predicted to increase especially in low-lying paddy fields. Mitigation measures, such as revising drainage planning and/or changing design standards for the capacity of drainage pumps may be necessary in the future.

  17. The Blackwater NWR inundation model. Rising sea level on a low-lying coast: land use planning for wetlands

    USGS Publications Warehouse

    Larsen, Curt; Clark, Inga; Guntenspergen, Glenn; Cahoon, Don; Caruso, Vincent; Hupp, Cliff; Yanosky, Tom

    2004-01-01

    shallow water surfaces has solved this problem. Our team has developed a detailed LIDAR map of the BNWR area at a 30 centimeter (ca. 1 ft) contour interval (figure 2). The new map allows us to identify the present marsh vegetation zones and to predict the location and area of future zones on a decade-by- decade basis over the next century at increments of sea level rise on the order of 3 cm/decade (ca. 1 inch). We have developed two scenarios for the model. The first is a steady-state model that uses the historic rate of sea level rise of 3.1 mm/yr to predict marsh areas. The second is a 'global warming' scenario utilizing a conservative IPCC model with an exponentially-increasing rate of sea level rise. Under either scenario, the BNWR is progressively inundated with an expanding core of open water. Although their positions change in the future, the areas of intertidal marsh as well as those of the critical high marsh remain fairly constant until the year 2050. Beyond that time, the low-lying land surface is overtopped by rising sea level and the area is dominated by open water. Our model suggests that wetland habitat in the Blackwater area might be maintained and sustained through a combination of public and private preservation efforts through easements in combination with judicious Federal land acquisition into the predicted areas of suitable marsh formation - but for only the next 50 years. Beyond that time much of this area will become open water.

  18. Electromagnetic mass splittings of the low lying hadrons and quark masses from 2+1 flavor lattice QCD+QED

    SciTech Connect

    Blum, Tom; Zhou Ran; Doi, Takumi; Hayakawa, Masashi; Izubuchi, Taku; Uno, Shunpei; Yamada, Norikazu

    2010-11-01

    Results computed in lattice QCD+QED are presented for the electromagnetic mass splittings of the low-lying hadrons. These are used to determine the renormalized, nondegenerate, light quark masses. It is found that m{sub u}{sup MS}=2.24(10)(34), m{sub d}{sup MS}=4.65(15)(32), and m{sub s}{sup MS}=97.6(2.9)(5.5) MeV at the renormalization scale 2 GeV, where the first error is statistical and the second systematic. We find the lowest-order electromagnetic splitting (m{sub {pi}{sup +}}-m{sub {pi}{sup 0}}){sub QED}=3.38(23) MeV, the splittings including next-to-leading order, (m{sub {pi}{sup +}}-m{sub {pi}{sup 0}}){sub QED}=4.50(23) MeV, (m{sub K{sup +}}-m{sub K{sup 0}}){sub QED}=1.87(10) MeV, and the m{sub u}{ne}m{sub d} contribution to the kaon mass difference, (m{sub K{sup +}}-m{sub K{sup 0}}){sub (m{sub u}-m{sub d})}=-5.840(96) MeV. All errors are statistical only, and the next-to-leading-order pion splitting is only approximate in that it does not contain all next-to-leading-order contributions. We also computed the proton-neutron mass difference, including for the first time, QED interactions in a realistic 2+1 flavor calculation. We find (m{sub p}-m{sub n}){sub QED}=0.383(68) MeV, (m{sub p}-m{sub n}){sub (m{sub u}-m{sub d})}=-2.51(14) MeV (statistical errors only), and the total m{sub p}-m{sub n}=-2.13(16)(70) MeV, where the first error is statistical, and the second, part of the systematic error. The calculations are carried out on QCD ensembles generated by the RBC and UKQCD collaborations, using domain wall fermions and the Iwasaki gauge action (gauge coupling {beta}=2.13 and lattice cutoff a{sup -1}{approx_equal}1.78 GeV). We use two lattice sizes, 16{sup 3} and 24{sup 3} ((1.8 fm){sup 3} and (2.7 fm){sup 3}), to address finite-volume effects. Noncompact QED is treated in the quenched approximation. The valence pseudoscalar meson masses in our study cover a range of about 250 to 700 MeV, though we use only those up to about 400 MeV to quote final results. We

  19. Variable Permanent Magnet Quadrupole

    SciTech Connect

    Mihara, T.; Iwashita, Y.; Kumada, M.; Spencer, C.M.; /SLAC

    2007-05-23

    A permanent magnet quadrupole (PMQ) is one of the candidates for the final focus lens in a linear collider. An over 120 T/m strong variable permanent magnet quadrupole is achieved by the introduction of saturated iron and a 'double ring structure'. A fabricated PMQ achieved 24 T integrated gradient with 20 mm bore diameter, 100 mm magnet diameter and 20 cm pole length. The strength of the PMQ is adjustable in 1.4 T steps, due to its 'double ring structure': the PMQ is split into two nested rings; the outer ring is sliced along the beam line into four parts and is rotated to change the strength. This paper describes the variable PMQ from fabrication to recent adjustments.

  20. New development of the projected shell model and description of low-lying collective states in transitional nuclei

    NASA Astrophysics Data System (ADS)

    Chen, Fang-Qi; Sun, Yang

    2013-12-01

    Description of the interplay between different nuclear shapes is an interesting but challenging problem. The original projected shell model (PSM) is applicable to nuclei with fixed shapes. We extend the PSM by superimposing (angular-momentum- and particle-number-) projected product wave functions in the spirit of the generate coordinate method. With this development, the Gd isotopes across the N = 90 region are studied, and the results indicate spectroscopic features of shape phase transition with varying neutron number. In order to illustrate the shape distribution in microscopic wave functions, we introduce a deformation representation and show that the collectively excited Kπ = 0+ states in the Gd isotopes have characters of shape vibration.

  1. Exploring the nature of low-lying excited-states in molecular crystals from many-body perturbation theory beyond the Tamm-Dancoff Approximation

    NASA Astrophysics Data System (ADS)

    Rangel, Tonatiuh; Sharifzadeh, Sahar; Rinn, Andre; da Jornada, Felipe H.; Shao, Meiyue; Witte, Gregor; Yang, Chao; Louie, Steven G.; Chatterjee, Sangaam; Kronik, Leeor; Neaton, Jeffrey B.

    Organic semiconductors have attracted attention due to their potential for optoelectronics and novel phenomena, such as singlet fission. Here, we use many-body perturbation theory to simulate neutral excitations in acene and perylene crystals. By diagonalizing the full Bethe-Salpether (BSE) Hamiltonian beyond the Tamm Dancoff approximation (TDA), we find that both low-lying excitation energies and oscillator strengths are in improved agreement with experiments relative to the TDA. We characterize the low-lying excitons, focusing in the degree of charge-transfer and spatial delocalization, connecting their relevance to singlet fission. For perylene, we find overall good agreement with absorption measurements, and we see evidence for the formation of an ``exciton-polariton'' band in β-perylene. This work is supported by the DOE.

  2. Theoretical explanation of the low-lying ν(6) vibrational fundamental of the FSO3 radical by the linear vibronic coupling approach.

    PubMed

    Uhlíková, Tereza; Urban, Štěpán

    2013-06-21

    The first attempt for a theoretical explanation of the ν6 fundamental energy levels of the fluorosulfate radical (FSO3) electronic ground state has been made. The vibronic interaction of the two lowest electronic states of the radical (X̃ (2)A2 and à (2)E) has been taken into consideration in the basis of the linear vibronic coupling (LVC) approximation. The strengths of the intrastate and interstate vibronic couplings have been calculated within the framework of the Köppel, Domcke, and Cederbaum (KDC) model Hamiltonian. Already this simple KDC-LVC model provides the ν6 fundamental energy, which is in very good agreement with the experimental results. From the inclusion of vibronic interactions such as the pseudo-Jahn-Teller and Jahn-Teller effects into the calculation of the fundamental energy of the ν6 mode, it can be said that mainly the interstate coupling with the electronic excited state E causes the unexpectedly low fundamental energy ν6 of the FSO3 radical.

  3. Threshold ionization spectroscopy of H2O, HDO and D2O and low-lying vibrational levels of HDO+ and D2O+

    NASA Astrophysics Data System (ADS)

    Lauzin, Clément; Jacovella, Ugo; Merkt, Frédéric

    2015-12-01

    Rotationally resolved photoelectron spectra of jet-cooled H2O, HDO and D2O have been recorded near the origin of the ? photoionising transition following single-photon ionization using the complementary techniques of mass-analysed threshold-ionization (MATI) and pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE) photoelectron spectroscopy. A gas mixture of H2O, HDO and D2O with Ar was obtained by mixing H2O (ℓ) and D2O (ℓ) in a reservoir and bubbling Ar gas through the mixture. To unambiguously assign the photoelectron bands to H2O, HDO or D2O, the PFI-ZEKE photoelectron spectra of the mixture were compared to MATI spectra and to spectra of H2O. Analysis of the rotational structure of the origin bands (v+1 = 0, v2+ = 0, v+3 = 0) ← (v1 = 0, v2 = 0, v3 = 0) of H2O, HDO and D2O and of the transitions to the (010), (020) and (100) levels of D2O+ and the first excited level of the O-D stretching mode of HDO+ provided new information on the photoionization dynamics of water and the energy level structure of HDO+ and D2O+.

  4. A potential-energy surface study of the 2A1 and low-lying dissociative states of the methoxy radical

    NASA Technical Reports Server (NTRS)

    Jackels, C. F.

    1985-01-01

    Accurate, ab initio quantum chemical techniques are applied in the present study of low lying bound and dissociative states of the methoxy radical at C3nu conformations, using a double zeta quality basis set that is augmented with polarization and diffuse functions. Excitation energy estimates are obtained for vertical excitation, vertical deexcitation, and system origin. The rate of methoxy photolysis is estimated to be too small to warrant its inclusion in atmospheric models.

  5. A potential-energy surface study of the 2A1 and low-lying dissociative states of the methoxy radical

    NASA Technical Reports Server (NTRS)

    Jackels, C. F.

    1985-01-01

    Accurate, ab initio quantum chemical techniques are applied in the present study of low lying bound and dissociative states of the methoxy radical at C3nu conformations, using a double zeta quality basis set that is augmented with polarization and diffuse functions. Excitation energy estimates are obtained for vertical excitation, vertical deexcitation, and system origin. The rate of methoxy photolysis is estimated to be too small to warrant its inclusion in atmospheric models.

  6. Observation of Excited Quadrupole-Bound States in Cold Anions

    NASA Astrophysics Data System (ADS)

    Zhu, Guo-Zhu; Liu, Yuan; Wang, Lai-Sheng

    2017-07-01

    We report the first observation of an excited quadrupole-bound state (QBS) in an anion. High-resolution photoelectron imaging of cryogenically cooled 4-cyanophenoxide (4 CP- ) anions yields an electron detachment threshold of 24 927 cm-1 . The photodetachment spectrum reveals a resonant transition 20 cm-1 below the detachment threshold, which is attributed to an excited QBS of 4 CP- because neutral 4CP has a large quadrupole moment with a negligible dipole moment. The QBS is confirmed by observation of seventeen above-threshold resonances due to autodetachment from vibrational levels of the QBS.

  7. Direct observation of the solvent effects on the low-lying nπ* and ππ* excited triplet states of acetophenone derivatives in thermal equilibrium.

    PubMed

    Narra, Sudhakar; Shigeto, Shinsuke

    2015-03-05

    Low-lying excited triplet states of aromatic carbonyl compounds exhibit diverse photophysical and photochemical properties of fundamental importance. Despite tremendous effort in studying those triplet states, the effects of substituents and solvents on the energetics of the triplet manifold and on photoreactivity remain to be fully understood. We have recently studied the ordering of the low-lying nπ* and ππ* excited triplet states and its substituent dependence in acetophenone derivatives using nanosecond time-resolved near-IR (NIR) spectroscopy. Here we address the other important issue, the solvent effects, by directly observing the electronic bands in the NIR that originate from the lowest nπ* and ππ* states of acetophenone derivatives in four solvents of different polarity (n-heptane, benzene, acetonitrile, and methanol). The two transient NIR bands decay synchronously in all the solvents, indicating that the lowest nπ* and ππ* states are in thermal equilibrium irrespective of the solvent polarity studied here. We found that the ππ* band increases in intensity relative to the nπ* band as solvent polarity increases. These results are compared with the photoreduction rate constant for the acetophenone derivatives in the solvents to which 2-propanol was added as a hydrogen-atom donor. Based on the present findings, we present a comprehensive, solvent- and substituent-dependent energy level diagram of the low-lying nπ* and ππ* excited triplet states.

  8. Low-lying excitations of poly-fused thiophene within Pariser-Parr-Pople model: A density matrix renormalization group study.

    PubMed

    Das, Mousumi

    2010-05-21

    We studied the nature of the ground and low-lying excited states of poly-fused thiophene oligomers within long-range Pariser-Parr-Pople (PPP) model Hamiltonian with up to 14 monomers using symmetrized density matrix renormalization group technique. Our results show that the lowest dipole-allowed state lies below the lowest dipole forbidden two-photon state, indicating that poly-fused thiophenes are strongly fluorescent. The lowest triplet state lies below the two-photon state, which is in agreement with the general trend in conjugated polymers. The charge density and bond order calculations of three low-lying excited states, along with the ground state of fused thiophene oligomers, show a significant transfer of charge from sulfur to adjacent carbon atom in the middle of the largest system size and these excitations are localized. The charge density and bond order calculations on singly and doubly doped states show that bipolarons are not stable entity in these systems. The calculations of low-lying excitations on radical cation and anion of fused thiophene oligomers show a new energy band in the low energy region, which is strongly coupled to its hole and electron conductivity. This implies that poly-fused thiophenes posses novel field-effect transistor properties.

  9. Two-term formula for ground band energy symmetry in low-lying levels of light Mg-Zr nuclei

    NASA Astrophysics Data System (ADS)

    Devi, Vidya

    2015-12-01

    In this paper, two parameter single-term energy formula EJ = aJb is used to study the energy spin relationship within the ground bands of even-even Mg-Zr nuclei. The formula works better for the γ-soft nuclei as well as vibrational nuclei. We also compared it with other two-parameter formulas: Ejiri, ab, pq and soft rotor formula (SRF). We also study the symmetry of the nuclei in the framework of interacting boson model (IBM-1). The IBM-1 was employed to determine the most appropriate Hamiltonian, the Hamiltonian of the IBM-1 and O(6) symmetry calculation, for the study of these isotopes. We have also calculated energy levels and B(E2) values for number of transitions in these 76-78Se and 76-78Kr isotopes and there is a good agreement between the presented results and the previous experimental data.

  10. Theoretical study on the low-lying excited states of the phosphorus monoiodide (PI) including the spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaomei; Liu, Xiaoting; Liang, Guiying; Li, Rui; Xu, Haifeng; Yan, Bing

    2016-01-01

    The potential energy curves (PECs) of the 22 Λ-S states of the phosphorus monoiodide (PI) molecule have been calculated at the level of MRCI+Q method with correlation-consistent quadruple-ζ quality basis set. The spectroscopic constants of the bound states are determined, which well reproduce the available measurements. The metastable a1Δ state has been reported for the first time, which lies between the X3Σ- and b1Σ+ states and have much deeper well than the ground state. The R-dependent spin-orbit (SO) matrix elements are calculated with the full-electron Breit-Pauli operator. Based on the SO matrix elements, the perturbations that the 23Π state may suffer from are analyzed in detail. The SOC effect makes the original Λ-S states split into 51 Ω states. In the zero-field splitting of the ground state X3Σ-, the spin-spin coupling contribution (2.23 cm-1) is found to be much smaller compared to the spin-orbit coupling contribution (50 cm-1). The avoided crossings between the Ω states lead to much shallower potential wells and the change of dissociation relationships of the states. The Ω-state wavefunctions are analyzed depending on their Λ-S compositions, showing the strong interactions among several quasidegenerate Λ-S states of the same total SO symmetry. The transition properties including electric dipole (E1), magnetic dipole (M1), and electric quadrupole (E2) transition moments (TMs), the Franck-Condon factors, the transition probabilities and the radiative lifetimes are computed for the transitions between Ω components of a1Δ and b1Σ+ states and ground state. The transition probabilities induced by the E1, E2, and M1 transitions are evaluated. The E2 makes little effect on transition probabilities. In contrast, the E1 transition makes the main contribution to the transition probability and the M1 transition also brings the influence that cannot be neglected. Finally, the radiative lifetimes are determined with the transition moments including E

  11. MQXFS1 Quadrupole Design Report

    SciTech Connect

    Ambrosio, Giorgio

    2016-04-14

    This report presents the reference design of MQXFS1, the first 1.5 m prototype of the low-beta quadrupoles (MQXF) for the LHC High Luminosity Upgrade. The MQXF quadrupoles have 150 mm aperture, coil peak field of about 12 T, and use $Nb_{3}Sn$ conductor. The design is based on the LARP HQ quadrupoles, which had 120 mm aperture. MQXFS1 has 1st generation cable cross-section and magnetic design.

  12. The low-lying electronic states and optical schemes for the laser cooling of the BH+ and BH- ions

    NASA Astrophysics Data System (ADS)

    Zhang, Qing-Qing; Yang, Chuan-Lu; Wang, Mei-Shan; Ma, Xiao-Guang; Liu, Wen-Wang

    2017-07-01

    The potential energy curves and transition dipole moments for the 12Σ+, 22Σ+, 12Π and 22Π electronic states of the two molecules are calculated using multi-reference configuration interaction and the large basis sets aug-cc-pwCV5Z. Based on the obtained potential energy curves, the rotational and vibrational energy levels of the states are obtained by solving the Schrödinger equation of nuclear motion, and the spectroscopic parameters are then obtained by fitting the energy levels to Dunham series expansions. The spin-orbit coupling effect of the 2Π states for both the BH+ cation and BH- anion are calculated. Highly diagonally distributed Franck-Condon factors are determined for the 12Σ+ (v″ = 0) ↔ 12Π (v‧ = 0) transition, ƒ00 (BH+) = 0.943, while the Franck-Condon factors for the 12Π (v″ = 0) ↔ 12Σ+ (v‧ = 0) transition is ƒ00 (BH-) = 0.942. Moreover, the radiative lifetime of 38.2 ns for the excited 12Π state of the BH+ and 91.8 ns for the 12Σ+ state of the BH- are obtained, which are short enough for rapid laser cooling. A three-step optical scheme of the laser cooling is constructed for either the BH+ cation or the BH- anion.

  13. The low-lying electronic states and optical schemes for the laser cooling of the BH(+) and BH(-) ions.

    PubMed

    Zhang, Qing-Qing; Yang, Chuan-Lu; Wang, Mei-Shan; Ma, Xiao-Guang; Liu, Wen-Wang

    2017-07-05

    The potential energy curves and transition dipole moments for the 1(2)Σ(+), 2(2)Σ(+), 1(2)Π and 2(2)Π electronic states of the two molecules are calculated using multi-reference configuration interaction and the large basis sets aug-cc-pwCV5Z. Based on the obtained potential energy curves, the rotational and vibrational energy levels of the states are obtained by solving the Schrödinger equation of nuclear motion, and the spectroscopic parameters are then obtained by fitting the energy levels to Dunham series expansions. The spin-orbit coupling effect of the (2)Π states for both the BH(+) cation and BH(-) anion are calculated. Highly diagonally distributed Franck-Condon factors are determined for the 1(2)Σ(+) (v″=0)↔1(2)Π (v'=0) transition, ƒ00 (BH(+))=0.943, while the Franck-Condon factors for the 1(2)Π (v″=0)↔1(2)Σ(+) (v'=0) transition is ƒ00 (BH(-))=0.942. Moreover, the radiative lifetime of 38.2ns for the excited 1(2)Π state of the BH(+) and 91.8ns for the 1(2)Σ(+) state of the BH(-) are obtained, which are short enough for rapid laser cooling. A three-step optical scheme of the laser cooling is constructed for either the BH(+) cation or the BH(-) anion. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Low-lying vibronic level structure of the ground state of the methoxy radical: Slow electron velocity-map imaging (SEVI) spectra and Köppel-Domcke-Cederbaum (KDC) vibronic Hamiltonian calculations

    DOE PAGES

    Weichman, Marissa L.; Cheng, Lan; Kim, Jongjin B.; ...

    2017-06-12

    A joint experimental and theoretical study is reported on the low-lying vibronic level structure of the ground state of the methoxy radical using slow photoelectron velocity-map imaging spectroscopy of cryogenically cooled, mass-selected anions (cryo-SEVI) and Köppel-Domcke-Cederbaum (KDC) vibronic Hamiltonian calculations. The KDC vibronic model Hamiltonian in the present study was parametrized using high-level quantum chemistry, allowing the assignment of the cryo-SEVI spectra for vibronic levels of CH3O up to 2000 cm–1 and of CD3O up to 1500 cm–1 above the vibrational origin, using calculated vibronic wave functions. The adiabatic electron affinities of CH3O and CD3O are determined from the cryo-SEVImore » spectra to be 1.5689 ± 0.0007 eV and 1.5548 ± 0.0007 eV, respectively, demonstrating improved precision compared to previous work. Experimental peak splittings of <10 cm–1 are resolved between the e1/2 and e3/2 components of the 61 and 51 vibronic levels. A pair of spin-vibronic levels at 1638 and 1677 cm–1 were predicted in the calculation as the e1/2 and e3/2 components of 62 levels and experimentally resolved for the first time. The strong variation of the spin-orbit splittings with a vibrational quantum number is in excellent agreement between theory and experiment. In conclusion, the observation of signals from nominally forbidden a1 vibronic levels in the cryo-SEVI spectra also provides direct evidence of vibronic coupling between ground and electronically excited states of methoxy.« less

  15. Low-lying vibronic level structure of the ground state of the methoxy radical: Slow electron velocity-map imaging (SEVI) spectra and Köppel-Domcke-Cederbaum (KDC) vibronic Hamiltonian calculations

    NASA Astrophysics Data System (ADS)

    Weichman, Marissa L.; Cheng, Lan; Kim, Jongjin B.; Stanton, John F.; Neumark, Daniel M.

    2017-06-01

    A joint experimental and theoretical study is reported on the low-lying vibronic level structure of the ground state of the methoxy radical using slow photoelectron velocity-map imaging spectroscopy of cryogenically cooled, mass-selected anions (cryo-SEVI) and Köppel-Domcke-Cederbaum (KDC) vibronic Hamiltonian calculations. The KDC vibronic model Hamiltonian in the present study was parametrized using high-level quantum chemistry, allowing the assignment of the cryo-SEVI spectra for vibronic levels of CH3O up to 2000 cm-1 and of CD3O up to 1500 cm-1 above the vibrational origin, using calculated vibronic wave functions. The adiabatic electron affinities of CH3O and CD3O are determined from the cryo-SEVI spectra to be 1.5689 ± 0.0007 eV and 1.5548 ± 0.0007 eV, respectively, demonstrating improved precision compared to previous work. Experimental peak splittings of <10 cm-1 are resolved between the e1/2 and e3/2 components of the 61 and 51 vibronic levels. A pair of spin-vibronic levels at 1638 and 1677 cm-1 were predicted in the calculation as the e1/2 and e3/2 components of 62 levels and experimentally resolved for the first time. The strong variation of the spin-orbit splittings with a vibrational quantum number is in excellent agreement between theory and experiment. The observation of signals from nominally forbidden a1 vibronic levels in the cryo-SEVI spectra also provides direct evidence of vibronic coupling between ground and electronically excited states of methoxy.

  16. Spectroscopic parameters of the low-lying electronic states and laser cooling feasibility of NH+ cation and NH- anion

    NASA Astrophysics Data System (ADS)

    Zhang, Qing-Qing; Yang, Chuan-Lu; Wang, Mei-Shan; Ma, Xiao-Guang; Liu, Wen-Wang

    2017-10-01

    The potential energy curves and transition dipole moments of 12Σ+, 22Σ+, 12Π and 22Π states of NH+ cation and NH- anion are calculated by using multi-reference configuration interaction method and large all-electron basis sets. Based on the obtained potential energy curves, the rotational and vibrational energy levels of the states are obtained by solving the Schrödinger equation of nuclear movement. The calculated spectroscopic parameters for NH+ cation and NH- anion are in good agreement with available theoretical and experimental results. The spin orbit coupling effect of the 2Π states for both NH+ cation and NH- anion are calculated. The feasibility of laser cooling of the two molecules is examined by using the results of the molecular structure and spectroscopy. The highly diagonal Franck-Condon factors for the 12Π (v″ = 0) ↔ 12Σ+ (v‧ = 0) transition of NH+ and NH- are 0.821 and 0.999, while the radiative lifetimes of the 12Σ+ (v‧ = 0) state for the two molecules are 384 ns and 52.4 ns, respectively. The results indicate that NH+ cation and NH- anion are good candidate molecules for laser cooling. The cooling scheme via Sisyphus process for the NH+ cation and NH- anion are proposed in the paper. The laser wavelengths for the close cycles of the absorption and radiation are also determined. Unfortunately, the potential energy curve of the ground state of the neutral NH molecule shows that the auto-detachment of NH- anion is possible, implying the optical scheme of laser cooling for NH- anion is not easy to achieve in the experiment although it has larger Franck-Condon factor.

  17. Spectroscopic parameters of the low-lying electronic states and laser cooling feasibility of NH(+) cation and NH(-) anion.

    PubMed

    Zhang, Qing-Qing; Yang, Chuan-Lu; Wang, Mei-Shan; Ma, Xiao-Guang; Liu, Wen-Wang

    2017-10-05

    The potential energy curves and transition dipole moments of 1(2)Σ(+), 2(2)Σ(+), 1(2)Π and 2(2)Π states of NH(+) cation and NH(-) anion are calculated by using multi-reference configuration interaction method and large all-electron basis sets. Based on the obtained potential energy curves, the rotational and vibrational energy levels of the states are obtained by solving the Schrödinger equation of nuclear movement. The calculated spectroscopic parameters for NH(+) cation and NH(-) anion are in good agreement with available theoretical and experimental results. The spin orbit coupling effect of the (2)Π states for both NH(+) cation and NH(-) anion are calculated. The feasibility of laser cooling of the two molecules is examined by using the results of the molecular structure and spectroscopy. The highly diagonal Franck-Condon factors for the 1(2)Π (v″=0)↔1(2)Σ(+) (v'=0) transition of NH(+) and NH(-) are 0.821 and 0.999, while the radiative lifetimes of the 1(2)Σ(+) (v'=0) state for the two molecules are 384ns and 52.4ns, respectively. The results indicate that NH(+) cation and NH(-) anion are good candidate molecules for laser cooling. The cooling scheme via Sisyphus process for the NH(+) cation and NH(-) anion are proposed in the paper. The laser wavelengths for the close cycles of the absorption and radiation are also determined. Unfortunately, the potential energy curve of the ground state of the neutral NH molecule shows that the auto-detachment of NH(-) anion is possible, implying the optical scheme of laser cooling for NH(-) anion is not easy to achieve in the experiment although it has larger Franck-Condon factor. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Californium-252 neutron intracavity brachytherapy alone for T1N0 low-lying rectal adenocarcinoma: A definitive anal sphincter-preserving radiotherapy.

    PubMed

    Xiong, Yanli; Shan, Jinlu; Liu, Jia; Zhao, Kewei; Chen, Shu; Xu, Wenjing; Zhou, Qian; Yang, Mei; Lei, Xin

    2017-01-17

    This study evaluated the 4-year results of 32 patients with T1N0 low-lying rectal adenocarcinoma treated solely with californium-252 (Cf-252) neutron intracavity brachytherapy (ICBT). Patients were solicited into the study from January 2008 to June 2011. All the patients had refused surgery or surgery was contraindicated. The patients were treated with Cf-252 neutron ICBT using a novel 3.5-cm diameter off-axis 4-channel intrarectal applicator designed by the authors. The dose reference point was defined on the mucosa surface, with a total dose of 55-62 Gy-eq/4 f (13-16 Gy-eq/f/wk). All the patients completed the radiotherapy in accordance with our protocol. The rectal lesions regressed completely, and the acute rectal toxicity was mild (≤G2). The 4-year local control, overall survival, disease-free survival, and late complication (≥G2) rates were 96.9%, 90.6%, 87.5% and 15.6%, respectively. No severe late complication (≥G3) occurred. The mean follow-up was 56.1 ± 16.0 months. At the end of last follow-up, 29 patients remained alive. The mean survival time was 82.1 ± 2.7 months. Cf-252 neutron ICBT administered as the sole treatment (without surgery) for patients with T1N0 low-lying rectal adenocarcinoma is effective with acceptable late complications. Our study and method offers a definitive anal sphincter-preserving radiotherapy for T1N0 low-lying rectal adenocarcinoma patients.

  19. Californium-252 neutron intracavity brachytherapy alone for T1N0 low-lying rectal adenocarcinoma: A definitive anal sphincter-preserving radiotherapy

    PubMed Central

    Xiong, Yanli; Shan, Jinlu; Liu, Jia; Zhao, Kewei; Chen, Shu; Xu, Wenjing; Zhou, Qian; Yang, Mei; Lei, Xin

    2017-01-01

    This study evaluated the 4-year results of 32 patients with T1N0 low-lying rectal adenocarcinoma treated solely with californium-252 (Cf-252) neutron intracavity brachytherapy (ICBT). Patients were solicited into the study from January 2008 to June 2011. All the patients had refused surgery or surgery was contraindicated. The patients were treated with Cf-252 neutron ICBT using a novel 3.5-cm diameter off-axis 4-channel intrarectal applicator designed by the authors. The dose reference point was defined on the mucosa surface, with a total dose of 55–62 Gy-eq/4 f (13–16 Gy-eq/f/wk). All the patients completed the radiotherapy in accordance with our protocol. The rectal lesions regressed completely, and the acute rectal toxicity was mild (≤G2). The 4-year local control, overall survival, disease-free survival, and late complication (≥G2) rates were 96.9%, 90.6%, 87.5% and 15.6%, respectively. No severe late complication (≥G3) occurred. The mean follow-up was 56.1 ± 16.0 months. At the end of last follow-up, 29 patients remained alive. The mean survival time was 82.1 ± 2.7 months. Cf-252 neutron ICBT administered as the sole treatment (without surgery) for patients with T1N0 low-lying rectal adenocarcinoma is effective with acceptable late complications. Our study and method offers a definitive anal sphincter-preserving radiotherapy for T1N0 low-lying rectal adenocarcinoma patients. PMID:28094790

  20. Probing the Low-lying Electronic States of Cyclobutanetetraone (C4O4) and its Radical Anion: A Low-Temperature Anion Photoelectron Spectroscopic Approach

    SciTech Connect

    Guo, Jin-Chang; Hou, Gaolei; Li, Si-Dian; Wang, Xue B.

    2012-02-02

    Despite a seemingly simple appearance, cyclobutanetetraone (C{sub 4}O{sub 4}) has four low-lying electronic states. Determining the energetic ordering of these states and the ground state of C{sub 4}O{sub 4}{sup -} theoretically has been proven to be considerably challenging and remains largely unresolved to date. Here we report a low-temperature negative ion photoelectron spectroscopic approach. A well structured spectrum with evenly spaced features was obtained at 193 nm due to excitation of the ring breathing mode of the C{sub 4}O{sub 4} neutral, whereas each 193-nm feature was observed to further split into a three-peak manifold at 266 nm assigned due to three electronic transitions from the ground state of the anion to the ground and two low-lying excited states of the neutral. Combined with recent theoretical studies and our own Franck-Condon factors simulations, the ground state of C{sub 4}O{sub 4}{sup -}, as well as the ground and two low-lying excited states of C{sub 4}O{sub 4} are determined to be {sup 2}A{sub 2u}, and {sup 3}B{sub 2u}, {sup 1}A{sub 1g} (8{pi}), {sup 1}B{sub 2u}, respectively. The frequency of the ring breathing mode (1810 {+-} 20 cm{sup -1}), the electron affinity (3.475 {+-} 0.005 eV), and the term values of {sup 1}A{sub 1g} (8{pi}) (6.27 {+-} 0.5 kJ/mol) and {sup 1}B{sub 2u} (13.50 {+-} 0.5 kJ/mol) are also directly obtained from the experiments.

  1. An SCF and MCSCF description of the low-lying states of MgO. [Configuration State Functions Multiconfiguration Self Consistent Field

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.; Silver, D. M.; Yarkony, D. R.

    1980-01-01

    The paper presents the multiconfiguration-self-consistent (MCSCF) and configuration state functions (CSF) for the low-lying electronic states of MgO. It was shown that simple description of these states was possible provided the 1 Sigma(+) states are individually optimized at the MCSCF level, noting that the 1(3 Sigma)(+) and 2(1 Sigma)(+) states which nominally result from the same electron occupation are separated energetically. The molecular orbitals obtained at this level of approximation should provide a useful starting point for extended configuration interaction calculations since they have been optimized for the particular states of interest.

  2. High level ab initio studies of the low-lying excited states in the H2OṡO2 complex

    NASA Astrophysics Data System (ADS)

    Robinson, Timothy W.; Kjaergaard, Henrik G.

    2003-08-01

    The lowest energy electronic transitions in the weakly bound van der Waals complex of water and oxygen (H2OṡO2) are studied using ab initio methods. The vertical excitation energies for the two low-lying singlet states are calculated with the complete active space self-consistent field and multireference configuration interaction (MRCI) methods, and are compared to those calculated in the oxygen molecule. The MRCI calculations predict blueshifts of about 150 and 250 cm-1 for the transition frequencies on formation of the complex. These calculated shifts can provide assistance towards the spectroscopic identification of H2OṡO2.

  3. Microscopic description of ground state magnetic moment and low-lying magnetic dipole excitations in heavy odd-mass 181Ta nucleus

    NASA Astrophysics Data System (ADS)

    Tabar, Emre; Yakut, Hakan; Kuliev, Ali Akbar

    2016-07-01

    The ground state magnetic moments and the low-lying magnetic dipole (Ml) transitions from the ground to excited states in heavy deformed odd-mass 181Ta have been microscopically investigated on the basis of the quasiparticle-phonon nuclear model (QPNM). The problem of the spurious state mixing in M1 excitations is overcome by a restoration method allowing a self-consistent determination of the separable effective restoration forces. Due to the self-consistency of the method, these effective forces contain no arbitrary parameters. The results of calculations are compared with the available experimental data, the agreement being reasonably satisfactory.

  4. An SCF and MCSCF description of the low-lying states of MgO. [Configuration State Functions Multiconfiguration Self Consistent Field

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.; Silver, D. M.; Yarkony, D. R.

    1980-01-01

    The paper presents the multiconfiguration-self-consistent (MCSCF) and configuration state functions (CSF) for the low-lying electronic states of MgO. It was shown that simple description of these states was possible provided the 1 Sigma(+) states are individually optimized at the MCSCF level, noting that the 1(3 Sigma)(+) and 2(1 Sigma)(+) states which nominally result from the same electron occupation are separated energetically. The molecular orbitals obtained at this level of approximation should provide a useful starting point for extended configuration interaction calculations since they have been optimized for the particular states of interest.

  5. Structure of Low-Lying Excited States of Guanine in DNA and Solution: Combined Molecular Mechanics and High-Level Coupled Cluster Studies

    DOE PAGES

    Kowalski, Karol; Valiev, Marat

    2007-01-01

    High-level ab-initio equation-of-motion coupled-cluster methods with singles, doubles, and noniterative triples are used, in conjunction with the combined quantum mechanical molecular mechanics approach, to investigate the structure of low-lying excited states of the guanine base in DNA and solvated environments. Our results indicate that while the excitation energy of the first excited state is barely changed compared to its gas-phase counterpart, the excitation energy of the second excited state is blue-shifted by 0.24 eV.

  6. One- and two-body densities of carbon isoelectronic series in their low-lying multiplet states from explicitly correlated wave functions.

    PubMed

    Gálvez, F J; Buendía, E; Sarsa, A

    2006-01-28

    The (3)P ground state and both the (1)D and (1)S excited states arising from the low-lying 1s(2)2s(2)2p(2) configuration of the carbon isoelectronic series are studied starting from explicitly correlated multiconfigurational wave functions. One- and two-body densities in position space have been calculated and different one- and two-body expectation values have been obtained. The effects of electronic correlations have been systematically studied. All the calculations have been done by means of variational Monte Carlo.

  7. A Star-Shaped Molecule with Low-Lying Lowest Unoccupied Molecular Orbital Level, n-Type Panchromatic Electrochromism, and Long-Term Stability.

    PubMed

    Yao, Bin; Zhou, Yue; Ye, Xichong; Wang, Rong; Zhang, Jie; Wan, Xinhua

    2017-04-03

    An electron-deficient star-shaped molecule based on anthraquinone imide was synthesized and characterized. It showed high electron accommodating capacity and strong electron-withdrawing ability with a low-lying lowest unoccupied molecular orbital (LUMO) of -4.10 eV. In addition, it exhibited panchromatic electrochromism attributed to the simultaneous presence of π*-π* transitions and intervalence charge transfer (IV-CT) upon one-electron reduction, and revealed long-term stability in electron gain and loss due to the proper LUMO energy level and ordered intermolecular assembly.

  8. Elastic and inelastic scattering to low-lying states of {sup 58}Ni and {sup 90}Zr using 240-MeV {sup 6}Li

    SciTech Connect

    Krishichayan; Chen, X.; Lui, Y.-W.; Tokimoto, Y.; Button, J.; Youngblood, D. H.

    2010-01-15

    Elastic and inelastic scattering of 240-MeV {sup 6}Li particles from {sup 58}Ni and {sup 90}Zr were measured with the multipole-dipole-multipole spectrometer from 4 deg. <={theta}{sub c.m.}<=43 deg. The elastic scattering data were fitted with the double-folding model using the density-dependent M3Y NN effective interaction and with a phenomenological Woods-Saxon potential. B(E2) and B(E3) values obtained for low-lying 2{sup +} and 3{sup -} states with the double-folding calculations agreed with the adopted values.

  9. Low-lying excited states and nonradiative processes of the adenine analogues 7H- and 9H-2-aminopurine.

    PubMed

    Lobsiger, Simon; Sinha, Rajeev K; Trachsel, Maria; Leutwyler, Samuel

    2011-03-21

    We have investigated the UV vibronic spectra and excited-state nonradiative processes of the 7H- and 9H-tautomers of jet-cooled 2-aminopurine (2AP) and of the 9H-2AP-d(4) and -d(5) isotopomers, using two-color resonant two-photon ionization spectroscopy at 0.3 and 0.045  cm(-1) resolution. The S(1) ← S(0) transition of 7H-2AP was observed for the first time. It lies ∼1600  cm(-1) below that of 9H-2AP, is ∼1000 times weaker and exhibits only in-plane vibronic excitations. In contrast, the S(1) ← S(0) spectra of 9H-2AP, 9H-2AP-d(4), and 9H-2AP-d(5) show numerous low-frequency bands that can be systematically assigned to overtone and combinations of the out-of-plane vibrations ν(1)', ν(2)', and ν(3)'. The intensity of these out-of-plane bands reflects an out-of-plane deformation in the (1)ππ∗(L(a)) state. Approximate second-order coupled-cluster theory also predicts that 2-aminopurine undergoes a "butterfly" deformation in its lowest (1)ππ∗ state. The rotational contours of the 9H-2AP, 9H-2AP-d(4), and 9H-2AP-d(5) 0(0)(0) bands and of eight vibronic bands of 9H-2AP up to 0(0)(0) + 600 cm(-1) exhibit 75%-80% in-plane (a∕b) polarization, which is characteristic for a (1)ππ∗ excitation. A 20%-25% c-axis (perpendicular) transition dipole moment component may indicate coupling of the (1)ππ∗ bright state to the close-lying (1)nπ∗ dark state. However, no (1)nπ∗ vibronic bands were detected below or up to 500  cm(-1) above the (1)ππ∗ 0(0)(0) band. Following (1)ππ∗ excitation, 9H-2AP undergoes a rapid nonradiative transition to a lower-lying long-lived state with a lifetime ≥5 μs. The ionization potential of 9H-2AP was measured via the (1)ππ∗ state (IP = 8.020 eV) and the long-lived state (IP > 9.10 eV). The difference shows that the long-lived state lies ≥1.08 eV below the (1)ππ∗ state. Time-dependent B3LYP calculations predict the (3)ππ∗ (T(1)) state 1.12 eV below the (1)ππ∗ state, but place the (1)n

  10. Bioacoustic and multi-locus DNA data of Ninox owls support high incidence of extinction and recolonisation on small, low-lying islands across Wallacea.

    PubMed

    Gwee, Chyi Yin; Christidis, Les; Eaton, James A; Norman, Janette A; Trainor, Colin R; Verbelen, Philippe; Rheindt, Frank E

    2017-04-01

    Known for their rich biodiversity and high level of endemism, the islands of Wallacea serve as natural laboratories for the study of spatio-temporal evolution and patterns of species diversification. Our study focuses on the owl genus Ninox, particularly the Southern Boobook (N. novaeseelandiae) and Moluccan Boobook (N. squamipila) complexes, which are widely distributed across Australasia. We conducted bioacoustic and multi-locus DNA analyses of 24 Ninox owl taxa to evaluate relationships and levels of divergence within the two complexes and ultimately assess the relationship between patterns of taxonomic differentiation and bioclimatic factors. We found that taxa that are vocally and/or genetically distinct from populations on the Australian mainland are found on islands that are significantly larger and higher in altitude than taxa that are vocally and/or genetically indistinct from populations on the Australian mainland. This pattern suggests that taxa occurring on small, low-lying Wallacean islands are likely to be recent colonisers that have dispersed from Australia. Overall, our observations demonstrate that the genus Ninox is likely to have colonised the Wallacean region multiple times as small, low-lying islands undergo frequent extinction, whereas populations on large and high-altitude islands are more resilient. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Feasibility of Rainwater Harvesting to fulfill potable water demand using quantitative water management in low-lying delta regions of Asia

    NASA Astrophysics Data System (ADS)

    Mahmood, A.; Hossain, F.

    2016-12-01

    Low-lying deltas of Asian region are usually densely populated and located in developing countries situated at the downstream end of major rivers. Extensive dam construction by the upstream countries has now caused water scarcity in large portions of low-lying deltas. Most inhabitants depend on shallow tube well for safe drinking water that tend to suffer from water quality issues (e.g. Arsenic contamination). In addition, people also get infected from water borne diseases like Cholera and Typhoid due to lack of safe drinking water. Developing a centralized piped network based water supply system is often not a feasible option in rural regions. Due to social acceptability, environment friendliness, lower capital and maintenance cost, rainwater harvesting can be the most sustainable option to supply safe drinking water in rural areas. In this study, first we estimate the monthly rainfall variability using long precipitation climatology from satellite precipitation data. The upper and lower bounds of monthly harvestable rainwater were estimated for each satellite precipitation grid. Taking this lower bound of monthly harvestable rainwater as input, we use quantitative water management concept to determine the percent of the time of the year potable water demand can be fulfilled. Analysis indicates that a 6 m³ reservoir tank can fulfill the potable water demand of a 6 person family throughout a year in almost all parts of this region.

  12. Recent Triplet Vibration Studies in RHIC

    SciTech Connect

    Thieberger, P.; Bonati, R.; Corbin, G.; Jain, A.; Minty, M.; McIntyre, G.; Montag, C.; Muratore, J.; Schultheiss, C.; Seberg, S.; Tuozzolo, J.

    2010-05-23

    We report on recent developments for mitigating vibrations of the quadrupole magnets near the interaction regions of the Relativistic Heavy Ion Collider (RHIC). High precision accelerometers, geophones, and a laser vibrometer were installed around one of the two interaction points to characterize the frequencies of the mechanical motion. In addition actuators were mounted directly on the quadrupole cryostats. Using as input the locally measured motion, dynamic damping of the mechanical vibrations has been demonstrated. In this report we present these measurements and measurements of the beam response. Future options for compensating the vibrations are discussed.

  13. Quadrupole-enhanced Raman scattering.

    PubMed

    Hastings, Simon P; Swanglap, Pattanawit; Qian, Zhaoxia; Fang, Ying; Park, So-Jung; Link, Stephan; Engheta, Nader; Fakhraai, Zahra

    2014-09-23

    Dark, nonradiating plasmonic modes are important in the Raman enhancement efficiency of nanostructures. However, it is challenging to engineer such hotspots with predictable enhancement efficiency through synthesis routes. Here, we demonstrate that spiky nanoshells have designable quadrupole resonances that efficiently enhance Raman scattering with unprecedented reproducibility on the single particle level. The efficiency and reproducibility of Quadrupole Enhanced Raman Scattering (QERS) is due to their heterogeneous structure, which broadens the quadrupole resonance both spatially and spectrally. This spectral breadth allows for simultaneous enhancement of both the excitation and Stokes frequencies. The quadrupole resonance can be tuned by simple modifications of the nanoshell geometry. The combination of tunability, high efficiency, and reproducibility makes these nanoshells an excellent candidate for applications such as biosensing, nanoantennaes, and photovoltaics.

  14. Low-lying electronic states and their nonradiative deactivation of thieno[3,4-b]pyrazine: An ab initio study

    NASA Astrophysics Data System (ADS)

    Guo, Xugeng; Cao, Zexing

    2012-12-01

    State-averaged complete active space self-consistent field (SA-CASSCF) calculations have been used to locate the four low-lying electronic states of thieno[3,4-b]pyrazine (TP), and their vertical excitation energies and emission energies have been determined by means of the multistate complete active space with second-order perturbation theory (MS-CASPT2) calculations. The present results indicate that the first weak 1nπ* excited state has a Cs-symmetry structure, unlike two bright 1ππ* excited states in C2v symmetry. The predicted vertical excitation energies of the three low-lying excited states in the gas phase are 3.41, 3.92, and 4.13 eV at the restricted-spin coupled-cluster single-double plus perturbative triple excitation [RCCSD(T)] optimized geometry, respectively. On the basis of calculations, a new assignment to the observed spectra of TP was proposed, in which the 1nπ* state should be responsible for the weak absorption centred at 3.54 eV and the two closely spaced 1ππ* states account for the two adjacent absorption bands observed at 3.99 and 4.15 eV. The predicted vertical emission energies lend further support to our assignments. Surface hopping dynamics simulations performed at the SA-CASSCF level suggest that the plausible deactivation mechanism comprises an ultrafast relaxation of the 1ππ* excited states to 1nπ* excited state, followed by a slow conversion to the S0 ground state via a conical intersection. This internal conversion is accessible, since the MS-CASPT2 predicted energy barrier is ˜0.55 eV, much lower than the Franck-Condon point populated initially under excitation. The dynamical simulations on the low-lying states for 500 fs reveal that the relatively high 1ππ* excited states can be easily trapped in the 1nπ* excited state, which will increase the lifetime of the excited thieno[3,4-b]pyrazine.

  15. Theoretical spectroscopy study of the low-lying electronic states of UX and UX+, X = F and Cl

    SciTech Connect

    Bross, David H.; Peterson, Kirk A.

    2015-11-13

    Spectroscopic constants (Te, re, B0, ωe, ωexe) have been calculated for the low-lying electronic states of UF, UF+, UCl, and UCl+ using complete active space 2nd-order perturbation theory (CASPT2), with a series of correlation consistent basis sets. The latter included those based on both pseudopotential (PP) and all-electron Douglas-Kroll-Hess (DK) Hamiltonians for the U atom. Spin orbit effects were included a posteri using the state interacting method using both PP and Breit Pauli (BP) operators, as well as from exact two-component (X2C) methods for U+ and UF+. Complete basis set (CBS) limits were obtained by extrapolation where possible and the PP and BP calculations were compared at their respective CBS limits. The PP-based method was shown to be reliable in calculating spectroscopic constants, in particular when using the state interacting method with CASPT2 energies (SO-CASPT2). The two component calculations were limited by computational resources and could not include electron correlation from the nominally closed shell 6s and 6p orbitals of U. UF and UCl were both calculated to have Ω=9/2 ground states. The first excited state of UCl was calculated to be an Ω=7/2 state at 78 cm-1 as opposed to the same state at 435 cm-1 in UF, and the other low-lying states of UCl showed a similar compression relative to UF. Likewise UF+ and UCl+ both have Ω=4 ground states and the manifold of low-lying excited Ω = 3, 2, 1, 0 states were energetically closer together in UCl+ than in UF+, ranging up to 776 cm-1 in UF+ and only 438 cm-1 in UCl+. As in previous research, the final PP-based SO-CASPT2 results for UF+ and UF agree well with experiment, and are expected to be predictive for UCl and UCl+, which are reported here for the first time.

  16. Observation of low-lying resonance states of He{sup {minus}} at the 2 {sup 1}S and 2 {sup 3}S He thresholds

    SciTech Connect

    Bader, A.; Sarkadi, L.; Vikor, L.; Kuzel, M.; Zavodszky, P.A.; Jalowy, T.; Groeneveld, K.O.; Macri, P.A.; Barrachina, R.O. ||||

    1997-01-01

    We measured the cusp electron production associated with target ionization at the impact of a 400-keV pure2{sup 3}S He beam and a mixed beam containing all three long-lived He states, i.e., 1{sup 1}S, 2{sup 1}S, and 2{sup 3}S. Using the results of an earlier experiment [Kuzel {ital et al.}, Phys. Rev. A {bold 48}, R1745 (1993)], we estimated the cross section for both metastable states of He. We found that the cusp for the 2{sup 1}S state is much larger and sharper than for the 2{sup 3}S state. The peaks are manifestations of excitation of low-lying virtual or weakly bound states of the He{sup {minus}} ion at the 2{sup 1}S and 2{sup 3}S thresholds. {copyright} {ital 1997} {ital The American Physical Society}

  17. Distal and proximal ligand interactions in heme proteins: Correlations between C-O and Fe-C vibrational frequencies, oxygen-17 and carbon-13 nuclear magnetic resonance chemical shifts, and oxygen-17 nuclear quadrupole coupling constants in C sup 17 O- and sup 13 CO-labeled species

    SciTech Connect

    Ki Deok Park; Guo, K.; Adebodun, F.; Chiu, M.L.; Sligar, S.G.; Oldfield, E. )

    1991-03-05

    The authors have obtained the oxygen-17 nuclear magnetic resonance (NMR) spectra of a variety of C{sup 17}O-labeled heme proteins, including sperm whale (Physeter catodon) myoglobin, two synthetic sperm whale myoglobin mutants (His E7 {yields} Val E7; His E7 {yields} Phe E7), adult human hemoglobin, rabbit (Oryctolagus cuniculus) hemoglobin, horseradish (Cochlearia armoracia) peroxidase isoenzymes A and C, and Caldariomyces fumago chloroperoxidase, in some cases as a function of pH, and have determined their isotropic {sup 17}O NMR chemical shifts, {delta}{sub i}, and spin-lattice relaxation times, T{sub 1}. They have also obtained similar results on a picket fence prophyrin. The results show an excellent correlation between the infrared C-O vibrational frequencies, {nu}(C-O), and {delta}{sub i}, between {nu}(C-O) and the {sup 17}O nuclear quadrupole coupling constant, and as expected between e{sup 2}qQ/h and {delta}{sub i}. The results suggest the IR and NMR measurements reflect the same interaction, which is thought to be primarily the degree of {pi}-back-bonding from Fe d to CO {pi}* orbitals, as outlined previously.

  18. Comparison of the AVI, modified SINTACS and GALDIT vulnerability methods under future climate-change scenarios for a shallow low-lying coastal aquifer in southern Finland

    NASA Astrophysics Data System (ADS)

    Luoma, Samrit; Okkonen, Jarkko; Korkka-Niemi, Kirsti

    2016-09-01

    A shallow unconfined low-lying coastal aquifer in southern Finland surrounded by the Baltic Sea is vulnerable to changes in groundwater recharge, sea-level rise and human activities. Assessment of the intrinsic vulnerability of groundwater under climate scenarios was performed for the aquifer area by utilising the results of a published study on the impacts of climate change on groundwater recharge and sea-level rise on groundwater-seawater interaction. Three intrinsic vulnerability mapping methods, the aquifer vulnerability index (AVI), a modified SINTACS and GALDIT, were applied and compared. According to the results, the degree of groundwater vulnerability is greatly impacted by seasonal variations in groundwater recharge during the year, and also varies depending on the climate-change variability in the long term. The groundwater is potentially highly vulnerable to contamination from sources on the ground surface during high groundwater recharge rates after snowmelt, while a high vulnerability to seawater intrusion could exist when there is a low groundwater recharge rate in dry season. The AVI results suggest that a change in the sea level will have an insignificant impact on groundwater vulnerability compared with the results from the modified SINTACS and GALDIT. The modified SINTACS method could be used as a guideline for the groundwater vulnerability assessment of glacial and deglacial deposits in inland aquifers, and in combination with GALDIT, it could provide a useful tool for assessing groundwater vulnerability to both contamination from sources on the ground surface and to seawater intrusion for shallow unconfined low-lying coastal aquifers under future climate-change conditions.

  19. Low-lying intruder and tensor-driven structures in 82As revealed by β decay at a new movable-tape-based experimental setup

    NASA Astrophysics Data System (ADS)

    Etilé, A.; Verney, D.; Arsenyev, N. N.; Bettane, J.; Borzov, I. N.; Cheikh Mhamed, M.; Cuong, P. V.; Delafosse, C.; Didierjean, F.; Gaulard, C.; Van Giai, Nguyen; Goasduff, A.; Ibrahim, F.; Kolos, K.; Lau, C.; Niikura, M.; Roccia, S.; Severyukhin, A. P.; Testov, D.; Tusseau-Nenez, S.; Voronov, V. V.

    2015-06-01

    The β decay of 82Ge Ge was re-investigated using the newly commissioned tape station BEDO at the electron-driven ISOL (isotope separation on line) facility ALTO operated by the Institut de Physique Nucléaire, Orsay. The original motivation of this work was focused on the sudden occurrence in the light N =49 odd-odd isotonic chain of a large number of J ≤1 states (positive or negative parity) in 80Ga by providing a reliable intermediate example, viz., 82As. The extension of the 82As level scheme towards higher energies from the present work has revealed three potential 1+ states above the already known one at 1092 keV. In addition our data allow ruling out the hypothesis that the 843 keV level could be a 1+ state. A detailed analysis of the level scheme using both an empirical core-particle coupling model and a fully microscopic treatment within a Skyrme-QRPA (quasiparticle random-phase approximation) approach using the finite-rank separable approximation was performed. From this analysis two conclusions can be drawn: (i) the presence of a large number of low-lying low-spin negative parity states is due to intruder states stemming from above the N =50 shell closure, and (ii) the sudden increase, from 82As to 80Ga, of the number of low-lying 1+ states and the corresponding Gamow-Teller fragmentation are naturally reproduced by the inclusion of tensor correlations and couplings to 2p-2h excitations.

  20. Vibration study of the APS magnet support assemblies

    SciTech Connect

    Wambsganss, M.W.; Jendrzejczyk, J.A.; Chen, S.S.

    1990-11-01

    Stability of the positron closed orbit is a requirement for successful operation of the Advanced Photon Source. The fact that vibration of the storage ring quadrupole magnets can lead to distortion of the positron closed orbit and to potentially unacceptable beam emittance growth provides the motivation for the subject studies. Low frequency vibrations can be controlled with steering magnets using feedback systems, provided the vibration amplitudes are within the dynamic range of the controllers. High frequency vibration amplitudes, on the other hand, are out of the range of the controller and, therefore must be limited to ensure the emittance growth will not exceed a prescribed value. Vibration criteria were developed based on the requirement that emittance growth be limited to 10 percent. Recognizing that the quadrupole magnets have the most significant effect, three different scenarios were considered: vibration of a single quadrupole within the storage ring, random vibration of all the quadrupoles in the ring, and the hypothetical case of a plane wave sweeping across the site and the quadrupoles following the motion of the plane wave. The maximum allowable peak vibration amplitudes corresponding to these three vibration scenarios are given. The criteria associated with the passage of a plane wave is dependent on wavelength, or, alternatively, on frequency given the wave speed. The wave speed used is that measured as a part of the geotechnical investigation at the APS site.

  1. Quadrupole Induced Resonant Particle Transport

    NASA Astrophysics Data System (ADS)

    Gilson, Erik; Fajans, Joel

    1999-11-01

    We have performed experiments that explore the effects of a magnetic quadrupole field on a pure electron plasma confined in a Malmberg-Penning trap. A model that we have developed describes the shape of the plasma and shows that a certain class of resonant particles follows trajectories that take them out of the plasma. Even though the quadrupole field destroys the cylindrical symmetry of the system, our theory predicts that if the electrons are off resonance, then the lifetime of the plasma will not be greatly affected by the quadrupole field. Our preliminary experimental results show that the shape of the plasma and the plasma lifetime agree with our model. We are investigating the scaling of this behavior with various experimental parameters such as the plasma length, density, and strength of the quadrupole field. In addition to being an example of resonant particle transport, this effect may find practical applications in experiments that plan to use magnetic quadrupole neutral atom traps to confine anti-hydrogen created in double-well positron/anti-proton Malmberg-Penning traps. (ATHENA Collaboration.)

  2. Quadrupole Induced Resonant Particle Transport

    NASA Astrophysics Data System (ADS)

    Gilson, Erik; Fajans, Joel

    1998-11-01

    We have performed experiments that explore the effects of a magnetic quadrupole field on a pure electron plasma confined in a Penning-Malmberg trap. A model that we have developed describes the shape of the plasma and shows that a certain class of resonant particles follows trajectories that take them out of the plasma. Even though the quadrupole field destroys the cylindrical symmetry of the system, our theory predicts that if the electrons are off resonance, then the lifetime of the plasma will not be greatly affected by the quadrupole field. Our preliminary experimental results show that the shape of the plasma and the plasma lifetime agree with our model. We are investigating the scaling of this behavior with various experimental parameters such as the plasma length, density, and strength of the quadrupole field. In addition to being an example of resonant particle transport, this effect may find practical applications in experiments that plan to use magnetic quadrupole neutral atom traps to confine anti-hydrogen created in double-well positron/anti-proton Penning-Malmberg traps. (ATHENA Collaboration.)

  3. Quadrupole moment of 203Fr

    NASA Astrophysics Data System (ADS)

    Wilkins, S. G.; Lynch, K. M.; Billowes, J.; Binnersley, C. L.; Bissell, M. L.; Cocolios, T. E.; Goodacre, T. Day; de Groote, R. P.; Farooq-Smith, G. J.; Flanagan, K. T.; Franchoo, S.; Ruiz, R. F. Garcia; Gins, W.; Heylen, H.; Koszorús, Á.; Neyens, G.; Stroke, H. H.; Vernon, A. R.; Wendt, K. D. A.; Yang, X. F.

    2017-09-01

    The spectroscopic electric quadrupole moment of the neutron-deficient francium isotope 203Fr was measured by using high-resolution collinear resonance ionization spectroscopy (CRIS) at the CERN Isotope Separation On-Line Device (ISOLDE) facility. A remeasurement of the 207Fr quadrupole moment was also performed, resulting in a departure from the established literature value. A sudden increase in magnitude of the 203Fr quadrupole moment, with respect to the general trend in the region, points to an onset of static deformation at N =116 in the 87Fr isotopic chain. Calculation of the static and total deformation parameters show that the increase in static deformation only cannot account for the observed departure of its relative charge radius from the 82Pb chain.

  4. Toward establishing low-lying Λ and Σ hyperon resonances with the K ¯+d →π +Y +N reaction

    NASA Astrophysics Data System (ADS)

    Kamano, H.; Lee, T.-S. H.

    2016-12-01

    A model for the K ¯d →π Y N reactions with Y =Λ ,Σ is developed, aiming at establishing the low-lying Λ and Σ hyperon resonances through analyzing the forthcoming data from the J-PARC E31 experiment. The off-shell amplitudes generated from the dynamical coupled-channels (DCC) model, which was developed in Kamano et al. [Phys. Rev. C 90, 065204 (2014), 10.1103/PhysRevC.90.065204], are used as input to the calculations of the elementary K ¯N →K ¯N and K ¯N →π Y subprocesses in the K ¯d →π Y N reactions. It is shown that the cross sections for the J-PARC E31 experiment with a rather high incoming-K ¯ momentum, | p⃗K ¯|=1 GeV, can be predicted reliably only when the input K ¯N →K ¯N amplitudes are generated from a K ¯N model, such as the DCC model used in this investigation, which describes the data of the K ¯N reactions at energies far beyond the K ¯N threshold. We find that the data of the threefold differential cross section d σ /(d Mπ Σd Ωp n) for the K-d →π Σ n reaction below the K ¯N threshold can be used to test the predictions of the resonance poles associated with Λ (1405 ) . We also find that the momentum dependence of the threefold differential cross sections for the K-d →π-Λ p reaction can be used to examine the existence of a low-lying JP=1 /2+ Σ resonance with a pole mass MR=1457 -i 39 MeV, which was found from analyzing the K-p reaction data within the employed DCC model.

  5. Morphological changes, beach inundation and overwash caused by an extreme storm on a low-lying embayed beach bounded by a dune system (NW Mediterranean)

    NASA Astrophysics Data System (ADS)

    Durán, Ruth; Guillén, Jorge; Ruiz, Antonio; Jiménez, José A.; Sagristà, Enric

    2016-12-01

    The geomorphological evolution of a low-lying, micro-tidal sandy beach in the western Mediterranean, Pals beach, was characterized using airborne Light Detection and Ranging (LiDAR) data. Data were collected in prior to and six months after the impact of an extreme storm with a return period of approx. 50 years, with the aim of characterizing the beach's response to the storm. The use of repeated high-resolution topographic data to quantify beach geomorphic changes has allowed assessment of the accuracy of different proxies for estimating beach volume changes. Results revealed that changes in the shoreline position cannot accurately reproduce beach volume changes on low-lying beaches where overwash processes are significant. Observations also suggested that volume estimations from beach profiles do not accurately represent subaerial volume changes at large profile distances on beaches with significant alongshore geomorphological variability. Accordingly, the segmentation of the beach into regularly spaced bins is proposed to assess alongshore variations in the beach volume with the accuracy of the topographic data. The morphological evolution of Pals beach during the study period showed a net shoreline retreat (- 4 m) and a significant sediment gain on the subaerial beach (+ 7.5 m3/m). The net gain of sediment is mostly due to the impact of the extreme storm, driving significant overwash processes that transport sediment landwards, increasing volume on the backshore and dunes. The increase of volume on the foreshore and the presence of cuspate morphologies along the shoreline also evidence post-storm beach recovery. Observed morphological changes exhibit a high variability along the beach related to variations in beach morphology. Changes in the morphology and migration of megacusps result in a high variability in the shoreline position and foreshore volume changes. On the other hand, larger morphological changes on the backshore and larger inundation distances

  6. Nuclear quadrupole resonance spectra database

    NASA Astrophysics Data System (ADS)

    Chihara, H.

    A computer-readable file of numerical data of nuclear quadrupole resonance frequency is being built which also serves as a bibliographic file. The data are compiled by reviewing original papers, reprints, and published data books and retrieving such data elements as substance names, nuclear mass number, temperature of measurements, resonance frequencies, nuclear quadrupole coupling constants, asymmetry parameters, and keywords. The database contains, if available, CAS registry number, molecular formulas and systematic names, and other synonyms of chemical substances. About 800 records have been loaded for online, TSS search through the Computer Center of Osaka University.

  7. Nuclear Quadrupole Moments and Nuclear Shell Structure

    DOE R&D Accomplishments Database

    Townes, C. H.; Foley, H. M.; Low, W.

    1950-06-23

    Describes a simple model, based on nuclear shell considerations, which leads to the proper behavior of known nuclear quadrupole moments, although predictions of the magnitudes of some quadrupole moments are seriously in error.

  8. Accretion disks around a mass with quadrupole

    NASA Astrophysics Data System (ADS)

    Abishev, M.; Boshkayev, K.; Quevedo, H.; Toktarbay, S.

    We consider the stability properties of circular orbits of test particles moving around a mass with quadrupole. We show that the quadrupole modifies drastically the properties of an accretion disk made of such test particles.

  9. Study of the β- decay of 116m1In: A new interpretation of low-lying 0+ states in 116Sn

    NASA Astrophysics Data System (ADS)

    Pore, J. L.; Cross, D. S.; Andreoiu, C.; Ashley, R.; Ball, G. C.; Bender, P. C.; Chester, A. S.; Diaz Varela, A.; Demand, G. A.; Dunlop, R.; Garnsworthy, A. B.; Garrett, P. E.; Hackman, G.; Hadinia, B.; Jigmeddorj, B.; Laffoley, A. T.; Liblong, A.; Kanungo, R.; Noakes, B.; Petrache, C. M.; Rajabali, M. M.; Starosta, K.; Svensson, C. E.; Voss, P. J.; Wang, Z. M.; Wood, J. L.; Yates, S. W.

    2017-02-01

    The 116Sn nucleus contains a collective rotational band originating from proton π 2 p-2 h excitations across the proton Z=50 shell gap. Even though this nucleus has been extensively investigated in the past, there was still missing information on the low-energy interband transitions connecting the intruder and normal structures. The low-lying structure of 116Sn was investigated through a high-statistics study of the β- decay of 116m1In with the 8π spectrometer and its ancillary detectors at TRIUMF. These measurements are critical in order to properly characterize the π 2 p-2 h rotational band. Weak γ-decay branches are observed utilizing γ-γ coincidence spectroscopy methods, leading to the first direct observation of the 85 keV 22+→ 03+ γ ray with a transition strength of B(E2) = 99.7(84) W.u. The analysis of these results strongly suggests that the 2027 keV 03+ state should replace the previously assigned 1757 keV 02+ state as the band-head of the π 2 p-2 h rotational band.

  10. The out-of-the-delta hypothesis: dense human populations in low-lying river deltas served as agents for the evolution of a deadly pathogen

    PubMed Central

    Boucher, Yan; Orata, Fabini D.; Alam, Munirul

    2015-01-01

    Cholera is a diarrheal disease that has changed the history of mankind, devastating the world with seven pandemics from 1817 to the present day. Although there is little doubt in the causative agent of these pandemics being Vibrio cholerae of the O1 serogroup, where, when, and how this pathogen emerged is not well understood. V. cholerae is a ubiquitous coastal species that likely existed for tens of thousands of years. However, the evolution of a strain capable of causing a large-scale epidemic is likely more recent historically. Here, we propose that the unique human and physical geography of low-lying river deltas made it possible for an environmental bacterium to evolve into a deadly human pathogen. Such areas are often densely populated and salt intrusion in drinking water frequent. As V. cholerae is most abundant in brackish water, its favored environment, it is likely that coastal inhabitants would regularly ingest the bacterium and release it back in the environment. This creates a continuous selection pressure for V. cholerae to adapt to life in the human gut. PMID:26539168

  11. Ab initio investigation of the ground and low-lying states of the diatomic fluorides TiF, VF, CrF, and MnF.

    PubMed

    Koukounas, Constantine; Kardahakis, Stavros; Mavridis, Aristides

    2004-06-22

    The electronic structure of the ground and low-lying states of the diatomic fluorides TiF, VF, CrF, and MnF was examined by multireference and coupled cluster methods in conjunction with extended basis sets. For a total of 34 states we report binding energies, spectroscopic constants, dipole moments, separation energies, and charge distributions. In addition, for all states we have constructed full potential curves. The suggested ground state binding energies of TiF(X (4)Phi), VF(X (5)Pi), CrF(X (6)Sigma(+)), and MnF(X (7)Sigma(+)) are 135, 130, 110, and 108 kcal/mol, respectively, with first excited states A (4)Sigma(-), A (5)Delta, A (6)Pi, and a (5)Sigma(+) about 2, 3, 23, and 19 kcal/mol higher. In essence all our numerical findings are in harmony with experimental results. For all molecules and states studied it is clear that the in situ metal atom (M) shows highly ionic character, therefore the binding is described realistically by M(+)F(-).

  12. Theoretical and jet spectroscopic investigations of energetics and structures for the low-lying singlet states of fluorene and 9,9'-spirobifluorene

    NASA Astrophysics Data System (ADS)

    Boo, Bong Hyun; Choi, Young Sik; Kim, Taek-Soo; Kang, Sung Kwon; Kang, Yong Hee; Lee, Sang Yeon

    1996-03-01

    Ab initio, semiempirical and spectroscopic studies of fluorene (FR) and 9,9'-spirobifluorene (SBF) were performed to elucidate π-orbital interaction between two fluorenyl rings of SBF and to predict the energies of the low-lying singlet electronic states of the molecules. Energies and symmetries of π-orbitals of FR and SBF molecules were determined by 3-21G and 6-31G∗ calculations on the optimized structures. The INDO/S-CIS semiempirical method was applied to predict the excited state energies, the transition dipole moments and the oscillator strengths for the optical transitions. Laser-induced fluorescence (LIF) excitation spectra were measured for FR and SBF cooled in pulsed supersonic expansions of He in the ranges 283.7-296.7 nm and 289.1-305.6 nm, respectively. In the LIF excitation spectra of FR and SBF, highly resolved vibronic bands were observed having the band origins of 33791 and 33047 cm -1, respectively. The spectral shift of the 0-0 band of SBF to red by 744 cm -1 may be attributed to the spiroconjugation arising from the interaction of four p π orbitals in the different planes.

  13. Effects of low-lying excitations on ground-state energy and energy gap of the Sherrington-Kirkpatrick model in a transverse field

    NASA Astrophysics Data System (ADS)

    Koh, Yang Wei

    2016-04-01

    We present an extensive numerical study of the Sherrington-Kirkpatrick model in a transverse field. Recent numerical studies of quantum spin glasses have focused on exact diagonalization of the full Hamiltonian for small systems (≈20 spins). However, such exact numerical treatments are difficult to apply on larger systems. We propose making an approximation by using only a subspace of the full Hilbert space spanned by low-lying excitations consisting of one-spin-flipped and two-spin-flipped states. The approximation procedure is carried out within the theoretical framework of the Hartree-Fock approximation and configuration interaction. Although not exact, our approach allows us to study larger system sizes comparable to that achievable by state-of-the-art quantum Monte Carlo simulations. We calculate two quantities of interest due to recent advances in quantum annealing, the ground-state energy and the energy gap between the ground and first excited states. For the energy gap, we derive a formula that enables it to be calculated using just the ground-state wave function, thereby circumventing the need to diagonalize the Hamiltonian. We calculate the scalings of the energy gap and the leading correction to the extensive part of the ground-state energy with system size, which are difficult to obtain with current methods.

  14. Excited state calculations using phaseless auxiliary-field quantum Monte Carlo: Potential energy curves of low-lying C(2) singlet states.

    PubMed

    Purwanto, Wirawan; Zhang, Shiwei; Krakauer, Henry

    2009-03-07

    We show that the recently developed phaseless auxiliary-field quantum Monte Carlo (AFQMC) method can be used to study excited states, providing an alternative to standard quantum chemistry methods. The phaseless AFQMC approach, whose computational cost scales as M(3)-M(4) with system size M, has been shown to be among the most accurate many-body methods in ground state calculations. For excited states, prevention of collapse into the ground state and control of the Fermion sign/phase problem are accomplished by the approximate phaseless constraint with a trial wave function. Using the challenging C(2) molecule as a test case, we calculate the potential energy curves of the ground and two low-lying singlet excited states. The trial wave function is obtained by truncating complete active space wave functions, with no further optimization. The phaseless AFQMC results using a small basis set are in good agreement with exact full configuration-interaction calculations, while those using large basis sets are in good agreement with experimental spectroscopic constants.

  15. Investigating nuclear shell structure in the vicinity of 78Ni: Low-lying excited states in the neutron-rich isotopes Zn,8280

    NASA Astrophysics Data System (ADS)

    Shiga, Y.; Yoneda, K.; Steppenbeck, D.; Aoi, N.; Doornenbal, P.; Lee, J.; Liu, H.; Matsushita, M.; Takeuchi, S.; Wang, H.; Baba, H.; Bednarczyk, P.; Dombradi, Zs.; Fulop, Zs.; Go, S.; Hashimoto, T.; Honma, M.; Ideguchi, E.; Ieki, K.; Kobayashi, K.; Kondo, Y.; Minakata, R.; Motobayashi, T.; Nishimura, D.; Otsuka, T.; Otsu, H.; Sakurai, H.; Shimizu, N.; Sohler, D.; Sun, Y.; Tamii, A.; Tanaka, R.; Tian, Z.; Tsunoda, Y.; Vajta, Zs.; Yamamoto, T.; Yang, X.; Yang, Z.; Ye, Y.; Yokoyama, R.; Zenihiro, J.

    2016-02-01

    The low-lying level structures of nuclei in the vicinity of 78Ni were investigated using in-beam γ -ray spectroscopy to clarify the nature of the nuclear magic numbers Z =28 and N =50 in systems close to the neutron drip line. Nucleon knockout reactions were employed to populate excited states in 80Zn and 82Zn. A candidate for the 41+ level in 80Zn was identified at 1979(30) keV, and the lifetime of this state was estimated to be 136-67+92 ps from a line-shape analysis. Moreover, the energy of the 21+ state in 82Zn is reported to lie at 621(11) keV. The large drop in the 21+ energy at 82Zn indicates the presence of a significant peak in the E (21+) systematics at N =50 . Furthermore, the E (41+) /E (21+) and B (E 2 ;41+→21+) /B (E 2 ;21+→0g.s . +) ratios in 80Zn were deduced to be 1.32 (3 ) and 1 .12-60+80 , respectively. These results imply that 80Zn can be described in terms of two-proton configurations with a 78Ni core and are consistent with a robust N =50 magic number along the Zn isotopic chain. These observations, therefore, indicate a persistent N =50 shell closure in nuclei far from the line of β stability, which in turn suggests a doubly magic structure for 78Ni.

  16. Cranking study of low lying yrast spectra and deformation systematics in some even-even neutron-deficient 130-136Nd

    NASA Astrophysics Data System (ADS)

    Sharma, Arun; Bharti, Arun; Khosa, S. K.

    2013-04-01

    In the present work, the results of calculations on various nuclear structure quantities in even-even neutron-deficient 130-136Nd using Cranked Hartree-Fock Bogoliubov (CHFB) technique have been presented. The various nuclear structure quantities that have been calculated in 130-136Nd isotopes are the yrast spectra, subshell occupation probabilities of various valence orbits and intrinsic quadrupole moments. Besides this, a comparative study of the calculated yrast spectra with the available experimental data as well as with the results of calculations obtained by using Variation-After-Projection (VAP) technique on these neutron - deficient 130-136Nd isotopes has also been presented.

  17. Quadrupole magnets for the SSC

    SciTech Connect

    Lietzke, A.; Barale, P.; Benjegerdes, R.; Caspi, S.; Cortella, J.; Dell`Orco, D.; Gilbert, W.; Green, M.I.; Mirk, K.; Peters, C.; Scanlan, R.; Taylor, C.E.; Wandesforde, A.

    1992-08-01

    At LBL, we have designed, constructed, and tested ten models (4-1meter, 6-5meter) of the Superconducting Super Collider (SSC) main-ring 5 meter focusing quadrupole magnet (211Tesla/meter). The results of this program are herein summarized.

  18. LCLS Undulator Quadrupole Fiducialization Plan

    SciTech Connect

    Wolf, Zachary; Levashov, Michael; Lundahl, Eric; Reese, Ed; LeCocq, Catherine; Ruland, Robert; /SLAC

    2010-11-24

    This note presents the fiducialization plan for the LCLS undulator quadrupoles. The note begins by summarizing the requirements for the fiducialization. A discussion of the measurement equipment is presented, followed by the methods used to perform the fiducialization and check the results. This is followed by the detailed fiducialization plan in which each step is enumerated. Finally, the measurement results and data storage formats are presented. The LCLS is made up of 33 assemblies consisting of an undulator, quadrupole, beam finder wire, and other components mounted on a girder. The components must be mounted in such a way that the beam passes down the axis of each component. In this note, we describe how the ideal beam axis is related to tooling balls on the quadrupole. This step, called fiducialization, is necessary because the ideal beam axis is determined magnetically, whereas tangible objects must be used to locate the quadrupole. The note begins with the list of fiducialization requirements. The laboratory in which the work will be performed and the relevant equipment is then briefly described. This is followed by a discussion of the methods used to perform the fiducialization and the methods used to check the results. A detailed fiducialization plan is presented in which all the steps of fiducialization are enumerated. A discussion of the resulting data files and directory structure concludes the note.

  19. Observation of b2 symmetry vibrational levels of the SO2C 1B2 state: Vibrational level staggering, Coriolis interactions, and rotation-vibration constants

    DOE PAGES

    Park, G. Barratt; Jiang, Jun; Saladrigas, Catherine A.; ...

    2016-04-14

    Here, the C 1B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. However, low-lying levels with odd quanta of antisymmetric stretch (b2 vibrational symmetry) have not previously been observed because transitions into these levels from the zero-point level of the X~ state are vibronically forbidden. We use IR-UV double resonance to observe the b2 vibrational levels of the C state below 1600 cm–1 of vibrational excitation. This enables a direct characterization of the vibrational level staggering that results from the double-minimum potential. In addition, itmore » allows us to deperturb the strong c-axis Coriolis interactions between levels of a1 and b2 vibrational symmetry, and to determine accurately the vibrational dependence of the rotational constants in the distorted C electronic state.« less

  20. Observation of b2 symmetry vibrational levels of the SO2 C̃ (1)B2 state: Vibrational level staggering, Coriolis interactions, and rotation-vibration constants.

    PubMed

    Park, G Barratt; Jiang, Jun; Saladrigas, Catherine A; Field, Robert W

    2016-04-14

    The C̃ (1)B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. However, low-lying levels with odd quanta of antisymmetric stretch (b2 vibrational symmetry) have not previously been observed because transitions into these levels from the zero-point level of the X̃ state are vibronically forbidden. We use IR-UV double resonance to observe the b2 vibrational levels of the C̃ state below 1600 cm(-1) of vibrational excitation. This enables a direct characterization of the vibrational level staggering that results from the double-minimum potential. In addition, it allows us to deperturb the strong c-axis Coriolis interactions between levels of a1 and b2 vibrational symmetry and to determine accurately the vibrational dependence of the rotational constants in the distorted C̃ electronic state.

  1. Nonequilibrium product distributions observed in the multiple collision chemiluminescent reaction of Sc with NO2. Perturbations, rapid energy transfer routes and evidence for a low-lying reservoir state

    NASA Astrophysics Data System (ADS)

    Gole, J. L.; Pace, S. A.

    1980-07-01

    Nitrogen dioxide reacts with scandium to yield the B 2Σ+-X 2Σ+ spectrum of ScO. This reaction has been characterized from 10-5 to 1 Torr in order to study relaxation and rapid intramolecular E-E transfer among ScO excited states. At the lowest pressures, a ground state metal atom interacts with a tenuous atmosphere of oxidant gas (beam-gas configuration). These ''single collision'' studies are extended in a controlled manner to higher pressure by entraining the metal atoms in argon and subsequently carrying out the oxidation of this mixture. At all pressures, the measured B 2Σ+ vibrational populations follow a markedly non-Boltzmann distribution. At the lowest pressures, the formation of ScO B 2Σ+ results directly from the reaction Sc+NO2→ScO*+NO. At higher pressures, the B 2Σ+ state is also populated via rapid intramolecular energy transfer from long-lived, weakly emitting ''reservoir'' states via the sequence Sc+NO2+Ar→ScO(res)+NO+Ar and ScO(res)+Ar→ScO(B 2Σ+)+Ar. Spin orbit and Coriolis interactions in ScO connect rovibronic levels of B 2Σ+ and low-lying 4Πr or 2Πi reservoir states resulting in the observation of substantial perturbations in B 2Σ+. Collisional energy transfer is particularly efficient for the most strongly perturbed levels of the B2Σ+ state. This energy transfer is manifest by the appearance of ''extra'' band heads representing normally forbidden (small electronic transition moment or Franck-Condon factor) ''reservoir state''- ground state transitions which become allowed because of a small admixture of B 2Σ+ character. The relative intensities of the extra and ''main'' B 2Σ+-X 2Σ+ transitions are strongly dependent on argon buffer gas pressure. A quantitative description of this dependence gives an estimate for the amount of mixing between the reservoir state and B 2Σ+ and for the rate of energy transfer between these two states. Collisional transfer to ScO B 2Σ+ v'=3-9 s found to proceed at rates which for certain levels

  2. Electron-impact excitation of Ni II. Collision strengths and effective collision strengths for low-lying fine-structure forbidden transitions

    NASA Astrophysics Data System (ADS)

    Cassidy, C. M.; Ramsbottom, C. A.; Scott, M. P.; Burke, P. G.

    2010-04-01

    Context. Considerable demand exists for electron excitation data for ion{Ni}{ii}, since lines from this abundant ion are observed in a wide variety of laboratory and astrophysical spectra. The accurate theoretical determination of these data can present a significant challenge however, due to complications arising from the presence of an open 3d-shell in the description of the target ion. Aims: In this work we present collision strengths and Maxwellian averaged effective collision strengths for the electron-impact excitation of ion{Ni}{ii}. Attention is concentrated on the 153 forbidden fine-structure transitions between the energetically lowest 18 levels of ion{Ni}{ii}. Effective collision strengths have been evaluated at 27 individual electron temperatures ranging from 30-100 000 K. To our knowledge this is the most extensive theoretical collisional study carried out on this ion to date. Methods: The parallel R-matrix package RMATRX II has recently been extended to allow for the inclusion of relativistic effects. This suite of codes has been utilised in the present work in conjunction with PSTGF to evaluate collision strengths and effective collision strengths for all of the low-lying forbidden fine-structure transitions. The following basis configurations were included in the target model - 3d9, 3d84s, 3d84p, 3d74s2 and 3d74s4p - giving rise to a sophisticated 295 jj-level, 1930 coupled channel scattering problem. Results: Comprehensive comparisons are made between the present collisional data and those obtained from earlier theoretical evaluations. While the effective collision strengths agree well for some transitions, significant discrepancies exist for others. Table 2 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/513/A55

  3. An ab initio study of the low-lying electronic states of YO2 and Franck-Condon simulation of the first photodetachment band of YO2(-).

    PubMed

    Lee, Edmond P F; Dyke, John M; Mok, Daniel K W; Chau, Foo-tim

    2008-05-15

    A variety of density functional theory and ab initio methods, including B3LYP, B98, BP86, CASSCF, CASSCF/RS2, CASSCF/MRCI, BD, BD(T), and CCSD(T), with ECP basis sets of up to the quintuple-zeta quality for Y, have been employed to study the X(2)B2 state of YO2 and the X(1)A1 state of YO2(-). Providing that the Y 4s(2)4p(6) outer-core electrons are included in the correlation treatment, the RCCSD(T) method gives the most consistent results and is concluded to be the most reliable and practical computational method for YO2 and YO2(-). In addition, RCCSD(T) potential energy functions (PEFs) of the X(2)B2 state of YO2 and the X(1)A1 state of YO2(-) were computed, employing the ECP28MDF_aug-cc-pwCVTZ and aug-cc-pVTZ basis sets for Y and O, respectively. Franck-Condon factors, which include allowance for Duschinsky rotation and anharmonicity, were calculated using the computed RCCSD(T) PEFs and were used to simulate the first photodetachment band of YO2(-). The simulated spectrum matches very well with the corresponding experimental 355 nm photodetachment spectrum of Wu, H.; Wang, L.-S. J. Phys. Chem. A 1998, 102, 9129, confirming the reliability of the RCCSD(T) PEFs used. Further calculations on low-lying electronic states of YO2 gave T(e)'s and T(vert)'s of the A(2)A1, B(2)B1, and C(2)A2 states of YO2, as well as EAs and VDEs to these states from the X(1)A1 state of YO2(-). On the basis of the ab initio VDEs obtained in the present study, previous assignments of the second and third photodetachment bands of YO2(-) have been revised.

  4. An ab initio investigation of the ground and low-lying singlet and triplet electronic states of XNO{sub 2} and XONO (X = Cl, Br, and I)

    SciTech Connect

    Peterson, Kirk A.; Francisco, Joseph S.

    2014-01-28

    A systematic ab initio treatment of the nitryl halides (XNO{sub 2}) and the cis- and trans- conformers of the halide nitrites (XONO), where X = Cl, Br, and I, have been carried out using highly correlated methods with sequences of correlation consistent basis sets. Equilibrium geometries and harmonic frequencies have been accurately calculated in all cases at the explicitly correlated CCSD(T)-F12b level of theory, including the effects of core-valence correlation for the former. Where experimental values are available for the equilibrium structures (ClNO{sub 2} and BrNO{sub 2}), the present calculations are in excellent agreement; however, the X-O distances are slightly too long by about 0.01 Å due to missing multireference effects. Accurate predictions for the iodine species are made for the first time. The vertical electronic excitation spectra have been calculated using equation-of-motion coupled cluster methods for the low-lying singlet states and multireference configuration interaction for both singlet and triplet states. The latter also included the effects of spin-orbit coupling to provide oscillator strengths for the ground state singlet to excited triplet transitions. While for ClNO{sub 2} the transitions to excited singlet states all occur at wavelengths shorter than 310 nm, there is one longer wavelength singlet transition in BrNO{sub 2} and two in the case of INO{sub 2}. The long wavelength tail in the XNO{sub 2} species is predicted to be dominated by transitions to triplet states. In addition to red-shifting from X = Cl to I, the triplet transitions also increase in oscillator strength, becoming comparable to many of the singlet transitions in the case of INO{sub 2}. Hence in particular, the latter species should be very photolabile. Similar trends are observed and reported for the halogen nitrites, many of which for the first time.

  5. Geo-statistical modeling to evaluate the socio-economic impacts of households in the context of low-lying areas conversion in Colombo metropolitan region-Sri Lanka

    NASA Astrophysics Data System (ADS)

    Hemakumara, GPTS; Rainis, Ruslan

    2015-02-01

    Living in Low-lying areas is a challenging task, but due to the lack of suitable land at affordable prices, thousands of householders have been establishing their own houses on Low-lying areas. Manipulation and conversion of low lying areas have led to an increase in the frequency and severity of micro disasters because the cumulative effect of these settlements is very high. Therefore, it is needed to examine how individual households have been emerging in Low-lying areas. This process is primarily influenced and controlled by Socio-economic factors. In the field survey conducted for this study, 388 householders were interviewed face to face to obtain the primary data. Collected data were applied to the Multivariate binary logistic Model. The Dependent variable of the model was set as Stable Houses and Non-Stable Houses based on the weighted values that were obtained from the field observations. Independent variables of this study are nine key aspects of the socio-economic conditions in these areas. Units of analysis of the study were taken as individual housing plots in the study area. The particular combination of Socio-Economic factors that exerted influence on each housing plot was measured using predicted probability value of logistic model and linked it with GIS land plot's map. Accuracy of Final Model is 86.9 % and probability level of influencing factors given a clear idea about household distribution and status while providing guidance about how the planning authorities should monitor and manage low lying areas, taking into consideration the present housing condition of these areas.

  6. Collective states of odd nuclei in a model with quadrupole-octupole degrees of freedom

    SciTech Connect

    Minkov, N. Drenska, S. B.; Yotov, P.; Bonatsos, D. Scheid, W.

    2007-08-15

    We apply the collective axial quadrupole-octupole Hamiltonian to describe the rotation-vibration motion of odd nuclei with Coriolis coupling between the even-even core and the unpaired nucleon.We consider that the core oscillates coherently with respect to the quadrupole and octupole axialdeformation variables. The coupling between the core and the unpaired nucleon provides a split paritydoublet structure of the spectrum. The formalism successfully reproduces the parity-doublet splitting in a wide range of odd-A nuclei. It provides model estimations for the third angular-momentum projection K on the intrinsic symmetry axis and the related intrinsic nuclear structure.

  7. Ab initio MRCI + Q calculations on the low-lying excited states of the MgBr radical including spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Wu, Dong-lan; Tan, Bin; Wen, Yu-feng; Zeng, Xue-feng; Xie, An-dong; Yan, Bing

    2016-05-01

    Accurate theoretical calculations on the MgBr radical have been carried out by using the high-level relativistic multireference configuration interaction method with Davidson correction (MRCI + Q) using correlation-consistent Quintuple-ζ quality basis set. The potential energy curves (PECs) of the 14 Λ-S states of MgBr have been computed. In order to improve the PECs, the core-valence correlation, scalar relativistic effect, and spin-orbit coupling effect are taken into account in the computations. The spectroscopic constants of the bound states have been determined from the computed PECs. The results of the ground state X2Σ+ and the first excited state A2Π are in good agreement with those from the available experiments, while spectroscopic constants of the other electronic states are firstly reported. The low-lying ion-pair state B2Σ+ correlated to ion-pair dissociation limit Mg+ (2Sg) + Br- (1Sg) is characterized. The permanent dipole moments (PDMs) of Λ-S states and the R-dependent spin-orbit (SO) matrix elements are computed. The results indicate that the abrupt changes of PDMs and the SO matrix elements are attributed to the changes of the electronic configurations near the avoided crossing point. After taking the SOC effect into account, the 14 Λ-S states split into 30 Ω states, and the SOC splitting for the A2Π is calculated to be 102.58 cm- 1. The SOC effect, leading to the double-well potential of the Ω = (3)1/2 state, is found to be substantial for MgBr. In order to further illustrate the SOC effect and the avoided crossing phenomenon of the PECs, the Λ-S compositions in the Ω state wavefunctions are analyzed in detail. Finally, the transition dipole moments (TDMs) of several transitions from upper Ω states to the ground X2Σ+1/2 state and the corresponding radiative lifetimes have been studied. It is shown that the (1)3/2-X2Σ+1/2 and (2)3/2-X2Σ+1/2 are particularly important to the observed transitions A2Π-X2Σ+ and C2Π-X2Σ+. The

  8. Water dynamics and nitrogen balance under different agricultural management practices in the low-lying plain of north-east Italy

    NASA Astrophysics Data System (ADS)

    Camarotto, Carlo; Dal Ferro, Nicola; Piccoli, Ilaria; Polese, Riccardo; Furlan, Lorenzo; Chiarini, Francesca; Berti, Antonio; Morari, Francesco

    2017-04-01

    In the last decades the adoption of sustainable land management practices (e.g. conservation agriculture, use of cover crops) has been largely subsidized by the EU policy in an attempt to combine competitive agricultural production with environmental protection, e.g. reduce nitrogen losses and optimize water management. However, the real environmental benefits of these practices is still questioned since strongly dependent on local pedo-climatic variability. This study aimed to evaluate water and nitrogen balances in sustainable land management systems including conservation agriculture (CA) practices or use of cover crops (CC). The experimental fields, established in 2010, are localized in the low-lying plain of the Veneto Region (NE Italy), characterized by a shallow water table and identified as Nitrate Vulnerable Zone. In March 2016, a total of nine soil-water monitoring stations have been installed in CA, CC and conventional fields. The stations (three per each field) were set up with multi-sensors probes (10 cm, 30 cm and 60 cm depth) for the continuous monitoring of soil electrical conductivity (EC, dS m-1), soil temperature (T, °C) and volumetric water content (WC, m3 m-3). A wireless system in ISM band has been designed to connect the soil-water monitoring stations to a unique access point, where the data were sent to a cloud platform via GSM. Water samples at each station were collected every two weeks using a suction cups (installed at 60 cm depth) and a phreatic wells, which were also used to record the water table level. Climatic data, collected from a weather station located in the experimental field, were combined with soil-water data to estimate water and nitrogen fluxes in the root zone. During the first year, relevant differences in water and nitrogen dynamics were observed between the treatments. It can be hypothesized that the combined effect of undisturbed soil conditions and continuous soil cover were major factors to affect water

  9. Assessment of the accuracy of density functionals for prediction of relative energies and geometries of low-lying isomers of water hexamers.

    PubMed

    Dahlke, Erin E; Olson, Ryan M; Leverentz, Hannah R; Truhlar, Donald G

    2008-05-01

    Water hexamers provide a critical testing ground for validating potential energy surface predictions because they contain structural motifs not present in smaller clusters. We tested the ability of 11 density functionals (four of which are local and seven of which are nonlocal) to accurately predict the relative energies of a series of low-lying water hexamers, relative to the CCSD(T)/aug'-cc-pVTZ level of theory, where CCSD(T) denotes coupled cluster theory with an interative treatment of single and double excitations and a quasi-perturbative treatment of connected triple excitations. Five of the density functionals were tested with two different basis sets, making a total of 16 levels of density functional theory (DFT) tested. When single-point energy calculations are carried out on geometries obtained with second-order Møller-Plesset perturbation theory (MP2), only three density functionals, M06-L, M05-2X, and M06-2X, are able to correctly predict the relative energy ordering of the hexamers. These three functionals predict that the range of energies spanned by the six isomers is 3.2-5.6 kcal/mol, whereas the other eight functionals predict ranges of 1.0-2.4 kcal/mol; the benchmark value for this range is 3.1 kcal/mol. When the hexamers are optimized at each level of theory, all methods are able to reproduce the MP2 geometries well for all isomers except the boat and bag isomers, and DFT optimization changes the energy ordering for seven of the 16 methods tested. The addition of zero-point energy changes the energy ordering for all of the density functionals studied except for M05-2X and M06-2X. The variation in relative energies predicted by the different methods highlights the necessity for exercising caution in the choice of density functionals used in future studies. Of the 11 density functionals tested, the most accurate results for energies were obtained with the PWB6K, MPWB1K, and M05-2X functionals.

  10. Distal and proximal ligand interactions in heme proteins: correlations between C-O and Fe-C vibrational frequencies, oxygen-17 and carbon-13 nuclear magnetic resonance chemical shifts, and oxygen-17 nuclear quadrupole coupling constants in C17O- and 13CO-labeled species.

    PubMed

    Park, K D; Guo, K M; Adebodun, F; Chiu, M L; Sligar, S G; Oldfield, E

    1991-03-05

    We have obtained the oxygen-17 nuclear magnetic resonance (NMR) spectra of a variety of C17O-labeled heme proteins, including sperm whale (Physeter catodon) myoglobin, two synthetic sperm whale myoglobin mutants (His E7----Val E7; His E7----Phe E7), adult human hemoglobin, rabbit (Oryctolagus cuniculus) hemoglobin, horseradish (Cochlearia armoracia) peroxidase (E.C. 1.11.1.7) isoenzymes A and C, and Caldariomyces fumago chloroperoxidase (E.C. 1.11.1.10), in some cases as a function of pH, and have determined their isotropic 17O NMR chemical shifts, delta i, and spin-lattice relaxation times, T1. We have also obtained similar results on a picket fence prophyrin, [5,10,15,20-tetrakis(alpha, alpha, alpha, alpha, alpha-pivalamidophenyl)porphyrinato]iron(II) (1-MeIm)CO, both in solution and in the solid state. Our results show an excellent correlation between the infrared C-O vibrational frequencies, v(C-O), and delta i, between v(C-O) and the 17O nuclear quadrupole coupling constant (e2qQ/h, derived from T1), and as expected between e2qQ/h and delta i. Taken together with the work of others on the 13C NMR of 13CO-labeled proteins, where we find an excellent correlation between delta i(13C) and v(Fe-C), our results suggest that IR and NMR measurements reflect the same interaction, which is thought to be primarily the degree of pi-back-bonding from Fe d to CO pi* orbitals, as outlined previously [Li, X.-Y., & Spiro, T.G. (1988) J. Am. Chem. Soc. 110, 6024]. The modulation of this interaction by the local charge field of the distal heme residue (histidine, glutamine, arginine, and possibly lysine) in a variety of species and mutants, as reflected in the NMR and IR measurements, is discussed, as is the effect of cysteine as the proximal heme ligand.

  11. Low-lying levels of 77Se studied by thermal neutron capture and evidence for a new term in the E2 operator of RQM (IBM)

    NASA Astrophysics Data System (ADS)

    Tokunaga, Y.; Seyfarth, H.; Meyer, R. A.; Schult, O. W. B.; Börner, H. G.; Barreau, G.; Faust, H. R.; Schreckenbach, K.; Brant, S.; Paar, V.; Vouk, M.; Vretenar, D.

    1985-06-01

    A high-resolution study of the 76Se(n, γ) reaction was carried out with curved-crystal and pair spectrometers and conversion electrons were measured following slow-neutron capture. The resulting data yield very precise level energies and spin and parity assignments for most of the levels. The neutron separation energy of 77Se was measured as 7418.85 ± 0.07 keV. The experimental data were compared with theoretical results for the level energies in 77Se and the E2, M1 and E1 branching ratios obtained from the SU(6) particle-vibration model (PTQM). We used 76Se as a slightly perturbed SU(5) vibrational core and the particle-vibration interaction strengths from the PTQM calculation for 75Se. In this frame there is evidence for a Δn = 2 term in the E2 operator. This term has not been included so far in TQM and IBM calculations.

  12. Low-lying electronic states of FeNC and FeCN: A theoretical journey into isomerization and quartet/sextet competition

    NASA Astrophysics Data System (ADS)

    DeYonker, Nathan J.; Yamaguchi, Yukio; Allen, Wesley D.; Pak, Chaeho; Schaefer, Henry F.; Peterson, Kirk A.

    2004-03-01

    With several levels of multireference and restricted open-shell single-reference electronic structure theory, optimum structures, relative energetics, and spectroscopic properties of the low-lying 6Δ, 6Π, 4Δ, 4Π, and 4Σ- states of linear FeNC and FeCN have been investigated using five contracted Gaussian basis sets ranging from Fe[10s8p3d], C/N[4s2p1d] to Fe[6s8p6d3f2g1h], C/N[6s5p4d3f2g]. Based on multireference configuration interaction (MRCISD+Q) results with a correlation-consistent polarized valence quadruple-zeta (cc-pVQZ) basis set, appended with core correlation and relativistic corrections, we propose the relative energies: Te(FeNC), 6Δ(0)<6Π (2300 cm-1)<4Δ (2700 cm-1)<4Π (4200 cm-1)<4Σ-; and Te(FeCN), 6Δ(0)<6Π (1800 cm-1)<4Δ (2500 cm-1)<4Π (2900 cm-1)<4Σ-. The 4Δ and 4Π states have massive multireference character, arising mostly from 11σ→12σ promotions, whereas the sextet states are dominated by single electronic configurations. The single-reference CCSDT-3 (coupled cluster singles and doubles with iterative partial triples) method appears to significantly overshoot the stabilization of the quartet states provided by both static and dynamical correlation. The 4,6Δ and 4,6Π states of both isomers are rather ionic, and all have dipole moments near 5 D. On the ground 6Δ surface, FeNC is predicted to lie 0.6 kcal mol-1 below FeCN, and the classical barrier for isocyanide/cyanide isomerization is about 6.5 kcal mol-1. Our data support the recent spectroscopic characterization by Lei and Dagdigian [J. Chem. Phys. 114, 2137 (2000)] of linear 6Δ FeNC as the first experimentally observed transition-metal monoisocyanide. Their assignments for the ground term symbol, isotopomeric rotational constants, and the Fe-N ω3 stretching frequency are confirmed; however, we find rather different structural parameters for 6Δ FeNC:re(Fe-N)=1.940 Å and r(N-C)=1.182 Å at the cc-pVQZ MRCISD+Q level. Our results also reveal that the observed band of Fe

  13. Nuclear collective motion with a coherent coupling interaction between quadrupole and octupole modes

    NASA Astrophysics Data System (ADS)

    Minkov, N.; Yotov, P.; Drenska, S.; Scheid, W.; Bonatsos, D.; Lenis, D.; Petrellis, D.

    2006-04-01

    A collective Hamiltonian for the rotation-vibration motion of nuclei is considered in which the axial quadrupole and octupole degrees of freedom are coupled through the centrifugal interaction. The potential of the system depends on the two deformation variables β2 and β3. The system is considered to oscillate between positive and negative β3 values by rounding an infinite potential core in the (β2,β3) plane with β2>0. By assuming a coherent contribution of the quadrupole and octupole oscillation modes in the collective motion, the energy spectrum is derived in an explicit analytic form, providing specific parity shift effects. On this basis several possible ways in the evolution of quadrupole-octupole collectivity are outlined. A particular application of the model to the energy levels and electric transition probabilities in alternating parity spectra of the nuclei Nd150, Sm152, Gd154, and Dy156 is presented.

  14. Potential energy curves of diatomic molecular ions from high-resolution photoelectron spectroscopy. III. The low-lying ungerade states of Kr2+

    NASA Astrophysics Data System (ADS)

    Wüest, A.; Merkt, F.

    2005-05-01

    Spectra of the v+ = 55 - 74 vibrational levels of the I(1/2u) ground electronic state and the v+ = 0 - 9 levels of the II(1/2u) excited electronic state of and 84Kr-86Kr+ have been measured by pulsed-field-ionization zero-kinetic-energy photoelectron spectroscopy. The spectra were recorded following (2+1' ) resonance-enhanced multiphoton excitation via several vibrational levels of the TMPH1285math002 Rydberg state of Kr2 located below the Kr(1S0) + Kr*(4p55p[1/2](J = 0)) dissociation limit. A combination of these results with earlier measurements of the vibrational level structure of the I(1/2u), I(3/2u) and II(1/2u) states of TMPH1285math003 was used to determine two sets of analytical potential energy curves for the first three electronic states of ungerade (u) symmetry of TMPH1285math004. The first set of curves was obtained without explicit consideration of the spin-orbit interaction by adjusting the potential parameters of three independent curves to fit the experimental data. The second set of curves was determined using a global potential model with explicit treatment of the spin-orbit interaction by adjusting the potential parameters of the TMPH1285math005 electronic states and assuming an R-independent spin-orbit coupling constant. Both sets of curves reproduce the experimental observations to within 8 cm-1. Although better agreement between calculated and observed vibronic energy levels was obtained with the former set of curves, this set requires a larger number of adjustable potential parameters (up to 12) and only accounts implicitly for the spin-orbit coupling. The latter set of curves offers the advantages of a global treatment of the u states, a much reduced number of adjustable parameters (only six), an explicit treatment of the spin-orbit interaction, and is in better agreement with ab initio quantum chemical predictions in the repulsive part of the potentials.

  15. Analysis of manifestation of strong quadrupole light-molecule interaction in the SEHR spectra

    SciTech Connect

    Polubotko, A. M.

    2011-11-15

    It is demonstrated that appearance of strong lines in surface-enhanced hyper-Raman (SEHR) spectra of phenazine and pyrazine, which are associated with totally symmetric vibrations, as well as other details of these spectra, can be explained using the dipole-quadrupole theory. The main point of this theory is the concept of strong quadrupole interaction of light with molecules, which arises in surface fields strongly varying in space near a rough metal surface. The theoretical results make it possible to correctly interpret the SEHR spectra of phenazine and pyrazine (namely, the emergence of the strong lines due to totally symmetric vibrations that are forbidden in usual hyper-Raman scattering), as well as other lines in the spectrum.

  16. Vibration manual

    NASA Technical Reports Server (NTRS)

    Green, C.

    1971-01-01

    Guidelines of the methods and applications used in vibration technology at the MSFC are presented. The purpose of the guidelines is to provide a practical tool for coordination and understanding between industry and government groups concerned with vibration of systems and equipments. Topics covered include measuring, reducing, analyzing, and methods for obtaining simulated environments and formulating vibration specifications. Methods for vibration and shock testing, theoretical aspects of data processing, vibration response analysis, and techniques of designing for vibration are also presented.

  17. A Merged Quadrupole-Calorimeter for CEPC

    NASA Astrophysics Data System (ADS)

    Talman, Richard; Hauptman, John

    The luminosity 𝓛 of colliding beams in a storage ring such as CEPC depends strongly on l*, the half-length of the free space centered on the intersection point (IP). l* is also the length from the IP to the front edges of the two near-in quadrupoles that are focusing the counter-circulating beams to the IP spot. The detector length cannot, therefore, exceed 2l*. Since 𝓛 increases strongly with decreasing l*, there is incentive for reducing l*; but this requires the detector to be shorter than desirable. This paper proposes a method for integrating these adjacent quadrupoles into the particle detector to retain (admittedly degraded) active particle detection of those forward going particles that would otherwise be obscured by the quadrupole. A gently conical quadrupole shape is more natural for merging the quadrupole into the particle detector than is the analytically exact cylindrical shape. This is true whether or not the calorimeter is integrated. It will be the task of accelerator physicists to determine the extent to which deviation from the pure quadrupole field compromises (or improves) accelerator performance. Superficially, both the presence of strongest gradient close to the IP and largest aperture farther from the IP seem to be advantageous. A tentative design for this merged, quadrupole-calorimeter is given.

  18. A merged quadrupole-calorimeter for CEPC

    NASA Astrophysics Data System (ADS)

    Talman, Richard; Hauptman, John

    2016-11-01

    The luminosity ℒ of colliding beams in a storage ring such as CEPC depends strongly on l∗, the half-length of the free space centered on the intersection point (IP). l∗ is also the length from the IP to the front edges of the two near-in quadrupoles that are focusing the counter-circulating beams to the IP spot. The detector length cannot, therefore, exceed 2l∗. Since ℒ increases strongly with decreasing l∗, there is incentive for reducing l∗; but this requires the detector to be shorter than desirable. This paper proposes a method for integrating these adjacent quadrupoles into the particle detector to retain (admittedly degraded) active particle detection of those forward going particles that would otherwise be obscured by the quadrupole. A gently conical quadrupole shape is more natural for merging the quadrupole into the particle detector than is the analytically exact cylindrical shape. This is true whether or not the calorimeter is integrated. It will be the task of accelerator physicists to determine the extent to which deviation from the pure quadrupole field compromises (or improves) accelerator performance. Superficially, both the presence of strongest gradient close to the IP and largest aperture farther from the IP seem to be advantageous. A tentative design for this merged, quadrupole-calorimeter is given.

  19. QUADRUPOLE BEAM-BASED ALIGNMENT AT RHIC.

    SciTech Connect

    NIEDZIELA, J.; MONTAG, C.; SATOGATA, T.

    2005-05-16

    Successful implementation of a beam-based alignment algorithm, tailored to different types of quadrupoles at RHIC, provides significant benefits to machine operations for heavy ions and polarized protons. This algorithm was used to calibrate beam position monitor centers relative to interaction region quadrupoles to maximize aperture. This approach was also used to determine the optimal orbit through transition jump quadrupoles to minimize orbit changes during the transition jump for heavy ion acceleration. This paper provides background discussion and results from first measurements during the RHIC 2005 run.

  20. Pressure-induced low-lying phonon modes softening and enhanced thermal resistance in β -M g2A l4S i5O18

    NASA Astrophysics Data System (ADS)

    Li, Yiran; Tian, Zhilin; Luo, Yixiu; Wang, Jiemin; Sun, Luchao; Zheng, Liya; Wang, Jingyang

    2017-02-01

    Lattice thermal conductivities of β -M g2A l4S i5O18 were predicted at various hydrostatic pressures based on some theoretical models. An abnormal decrement on lattice thermal conductivity is observed for compressed crystal structure. A rigorous analysis of structural stability, bonding characteristics, vibration modes, group velocities, and mode Grüneisen parameters helps us to recognize the origin of this anomalous behavior. We attribute the negative dependent trend to the softening of low frequency phonons and strengthening of anharmonicity at elevated pressure, both of which arise from the specific corner-linked tetrahedral framework in the crystal structure. To validate theoretical calculations, we synthesized pure and dense β -M g2A l4S i5O18 ceramic by using a two-step processing method and determined its intrinsic lattice thermal conductivity by successfully eliminating the phonon scattering from defects and high-temperature thermal radiation. The experimental intrinsic values agreed quite well with the theoretical predictions. This paper reports an anomalous pressure-induced reduction of lattice thermal conductivity and also provides a key insight into the interesting phonon modification mechanism through tailoring the crystal structure of complex compounds.

  1. Time-dependent Hartree-Fock Study of Octupole Vibrations in doubly magic nuclei

    NASA Astrophysics Data System (ADS)

    Simenel, C.; Buete, J.; Vo-Phuoc, K.

    2016-09-01

    Octupole vibrations are studied in some doubly magic nuclei using the time-dependent Hartree-Fock (TDHF) theory with a Skyrme energy density functional. Through the use of the linear response theory, the energies and transition amplitudes of the low-lying vibrational modes for each of the nuclei were determined. Energies were found to be close to experimental results. However, transition amplitudes, quantified by the deformation parameter β3, are underestimated by TDHF. A comparison with single-particle excitations on the Hartree-Fock ground-state shows that the collective octupole vibrations have their energy lowered due to attractive RPA residual interaction.

  2. Unusual chemical bonding in the beryllium dimer and its twelve vibrational levels

    NASA Astrophysics Data System (ADS)

    Mitin, A. V.

    2017-08-01

    The ab initio calculations have shown that the atoms in the beryllium dimer are covalently bound at the low-lying vibrational energy levels with ν = 0-4, while at the higher levels with ν = 5-11 the atoms are bonded by the van der Waals forces near the right turning points. The developed ab initio modified EMO potential function, in distinction with the original EMO function, which was used for a description of the experimental vibrational levels, not only has the correct dissociation energy, but also describes all twelve vibrational energy levels with a smaller RMS error of less than 0.4 cm-1.

  3. Clusterization and quadrupole deformation in nuclei

    SciTech Connect

    Cseh, J.; Algora, A.; Antonenko, N. V.; Jolos, R. V.; Scheid, W.; Darai, J.; Hess, P. O.

    2006-04-26

    We study the interrelation of the clusterization and quadrupole deformation of atomic nuclei, by applying cluster models. Both the energetic stability and the exclusion principle is investigated. Special attention is paid to the relative orientations of deformed clusters.

  4. Nonuniform radiation damage in permanent magnet quadrupoles.

    PubMed

    Danly, C R; Merrill, F E; Barlow, D; Mariam, F G

    2014-08-01

    We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL's pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

  5. Nonuniform radiation damage in permanent magnet quadrupoles

    SciTech Connect

    Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G.

    2014-08-15

    We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

  6. Permanent magnet edge-field quadrupole

    DOEpatents

    Tatchyn, Roman O.

    1997-01-01

    Planar permanent magnet edge-field quadrupoles for use in particle accelerating machines and in insertion devices designed to generate spontaneous or coherent radiation from moving charged particles are disclosed. The invention comprises four magnetized rectangular pieces of permanent magnet material with substantially similar dimensions arranged into two planar arrays situated to generate a field with a substantially dominant quadrupole component in regions close to the device axis.

  7. Permanent magnet edge-field quadrupole

    DOEpatents

    Tatchyn, R.O.

    1997-01-21

    Planar permanent magnet edge-field quadrupoles for use in particle accelerating machines and in insertion devices designed to generate spontaneous or coherent radiation from moving charged particles are disclosed. The invention comprises four magnetized rectangular pieces of permanent magnet material with substantially similar dimensions arranged into two planar arrays situated to generate a field with a substantially dominant quadrupole component in regions close to the device axis. 10 figs.

  8. Integrally formed radio frequency quadrupole

    DOEpatents

    Abbott, Steven R.

    1989-01-01

    An improved radio frequency quadrupole (10) is provided having an elongate housing (11) with an elongate central axis (12) and top, bottom and two side walls (13a-d) symmetrically disposed about the axis, and vanes (14a-d) formed integrally with the walls (13a-d), the vanes (14a-d) each having a cross-section at right angles to the central axis (12) which tapers inwardly toward the axis to form electrode tips (15a-d) spaced from each other by predetermined distances. Each of the four walls (13a-d), and the vanes (14a-d) integral therewith, is a separate structural element having a central lengthwise plane (16) passing through the tip of the vane, the walls (13a-d) having flat mounting surfaces (17, 18) at right angles to and parallel to the control plane (16), respectively, which are butted together to position the walls and vane tips relative to each other.

  9. Miniature quadrupole mass spectrometer array

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor); Hecht, Michael H. (Inventor); Orient, Otto J. (Inventor)

    1997-01-01

    The present invention provides a minature quadrupole mass spectrometer array for the separation of ions, comprising a first pair of parallel, planar, nonmagnetic conducting rods each having an axis of symmetry, a second pair of planar, nonmagnetic conducting rods each having an axis of symmetry parallel to said first pair of rods and disposed such that a line perpendicular to each of said first axes of symmetry and a line perpendicular to each of said second axes of symmetry bisect each other and form a generally 90 degree angle. A nonconductive top positioning plate is positioned generally perpendicular to the first and second pairs of rods and has an aperture for ion entrance along an axis equidistant from each axis of symmetry of each of the parallel rods, a nonconductive bottom positioning plate is generally parallel to the top positioning plate and has an aperture for ion exit centered on an axis equidistant from each axis of symmetry of each of the parallel rods, means for maintaining a direct current voltage between the first and second pairs of rods, and means for applying a radio frequency voltage to the first and second pairs of rods.

  10. Miniature quadrupole mass spectrometer array

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor); Hecht, Michael H. (Inventor); Orient, Otto J. (Inventor)

    1998-01-01

    The present invention provides a minature quadrupole mass spectrometer array for the separation of ions, comprising a first pair of parallel, planar, nonmagnetic conducting rods each having an axis of symmetry, a second pair of planar, nonmagnetic conducting rods each having an axis of symmetry parallel to said first pair of rods and disposed such that a line perpendicular to each of said first axes of symmetry and a line perpendicular to each of said second axes of symmetry bisect each other and form a generally 90 degree angle. A nonconductive top positioning plate is positioned generally perpendicular to the first and second pairs of rods and has an aperture for ion entrance along an axis equidistant from each axis of symmetry of each of the parallel rods, a nonconductive bottom positioning plate is generally parallel to the top positioning plate and has an aperture for ion exit centered on an axis equidistant from each axis of symmetry of each of the parallel rods, means for maintaining a direct current voltage between the first and second pairs of rods, and means for applying a radio frequency voltage to the first and second pairs of rods.

  11. Folding model analysis of 240 MeV {sup 6}Li elastic scattering on {sup 116}Sn and inelastic scattering to low-lying states of {sup 116}Sn

    SciTech Connect

    Chen, X.; Lui, Y.-W.; Clark, H. L.; Tokimoto, Y.; Youngblood, D. H.

    2007-11-15

    Elastic scattering of 240 MeV {sup 6}Li ions from {sup 116}Sn was measured from 4 deg.{<=}{theta}{sub c.m.}{<=}32 deg. The data were fitted with a Woods-Saxon phenomenological potential and with double folding models using the M3Y NN effective interaction with and without density dependence. DWBA calculations with the fitted parameters were used to calculate cross sections for inelastic scattering to low-lying 2{sup +}and 3{sup -} states. B(E2) and B(E3) values were extracted and compared with electromagnetic values and those obtained from {alpha} inelastic scattering.

  12. Density Functional Theory in Transition-Metal Chemistry: Relative Energies of Low-Lying States of Iron Compounds and the Effect of Spatial Symmetry Breaking

    SciTech Connect

    Sorkin, Anastassia; Iron, Mark A.; Truhlar, Donald G.

    2008-02-01

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The ground and lower excited states of Fe2, Fe2 -, and FeO+ were studied using a number of density functional theory (DFT) methods. Specific attention was paid to the relative state energies, the internuclear distances (re), and the harmonic vibrational frequencies (öe). A number of factors influencing the calculated values of these properties were examined. These include basis sets, the nature of the density functional chosen, the percentage of Hartree- Fock exchange in the density functional, and constraints on orbital symmetry. A number of different types of generalized gradient approximation (GGA) density functionals (straight GGA, hybrid GGA, meta-GGA, and hybrid meta-GGA) were examined, and it was found that the best results were obtained with hybrid GGA or hybrid meta-GGA functionals that contain nonzero fractions of HF exchange; specifically, the best overall results were obtained with B3LYP, M05, and M06, closely followed by B1LYP. One significant observation was the effect of enforcing symmetry on the orbitals. When a degenerate orbital (ð or ä) is partially occupied in the 4¼ excited state of FeO+, reducing the enforced symmetry (from C6v to C4v to C2v) results in a lower energy since these degenerate orbitals are split in the lower symmetries. The results obtained were compared to higher level ab initio results from the literature and to recent PBE+U plane wave results by Kulik et al. (Phys. Rev. Lett. 2006, 97, 103001). It was found that some of the improvements that were afforded by the semiempirical +U correction can also be accomplished by improving the form of the DFT functional and, in one case, by not enforcing high symmetry on the orbitals.

  13. Quadrupole-bound anions: efficacy of positive versus negative quadrupole moments.

    PubMed

    Garrett, W R

    2012-02-07

    A pseudopotential method is utilized to study the critical stability of model anions formed by long-range quadrupolar molecular potentials. Results indicate that critical quadrupole moments of simple point-charge triads do not serve well as predictors of real quadrupole-bound anions of systems with negative moments.

  14. SUPERCONDUCTING QUADRUPOLE ARRAYS FOR MULTIPLE BEAM TRANSPORT

    SciTech Connect

    Rainer Meinke Carl Goodzeit Penny Ball Roger Bangerter

    2003-10-01

    The goal of this research was to develop concepts for affordable, fully functional arrays of superconducting quadrupoles for multi-beam transport and focusing in heavy ion fusion (HIF)accelerators. Previous studies by the Virtual National Laboratory (VNL) collaboration have shown that the multi-beam transport system (consisting of alternating gradient quadrupole magnets, a beam vacuum system, and the beam monitor and control system) will likely be one of the most expensive and critical parts of such an accelerator. This statement is true for near-term fusion research accelerators as well as accelerators for the ultimate goal of power production via inertial fusion. For this reason, research on superconducting quadrupole arrays is both timely and important for the inertial fusion energy (IFE) research program. This research will also benefit near-term heavy ion fusion facilities such as the Integrated Research Experiment (IRE)and/or the Integrated Beam Experiment (IBX). We considered a 2-prong approach that addresses the needs of both the nearer and longer term requirements of the inertial fusion program. First, we studied the flat coil quadrupole design that was developed by LLNL; this magnet is 150 mm long with a 50 mm aperture and thus is suitable for near term experiments that require magnets of a small length to aperture ratio. Secondly, we studied the novel double-helix quadrupole (DHQ) design in a small (3 x 3) array configuration; this design can provide an important step to the longer term solution of low-cost, easy to manufacture array constructions. Our Phase I studies were performed using the AMPERES magnetostatic analysis software. Consideration of these results led to plans for future magnet R&D construction projects. The first objective of Phase I was to develop the concept of a superconducting focusing array that meets the specific requirements of a heavy ion fusion accelerator. Detailed parameter studies for such quadrupole arrays were performed

  15. Focusing properties of discrete RF quadrupoles

    NASA Astrophysics Data System (ADS)

    Li, Zhi-Hui; Wang, Zhi-Jun

    2017-08-01

    The particle motion equation for a Radio Frequency (RF) quadrupole is derived. The motion equation shows that the general transform matrix of a RF quadrupole with length less than or equal to 0.5βλ (β is the relativistic velocity of particles and λ is wavelength of radio frequency electromagnetic field) can describe the particle motion in an arbitrarily long RF quadrupole. By iterative integration, the general transform matrix of a discrete RF quadrupole is derived from the motion equation. The transform matrix is in form of a power series of focusing parameter B. It shows that for length less than βλ, the series up to the 2nd order of B agrees well with the direct integration results for B up to 30, while for length less than 0.5βλ, the series up to 1st order is already a good approximation of the real solution for B less than 30. The formula of the transform matrix can be integrated into linac or beam line design code to deal with the focusing of discrete RF quadrupoles. Supported by National Natural Science Foundation of China (11375122, 11511140277) and Strategic Priority Research Program of the Chinese Academy of Sciences (XDA03020705)

  16. Induced CMB quadrupole from pointing offsets

    SciTech Connect

    Moss, Adam; Scott, Douglas; Sigurdson, Kris E-mail: dscott@phas.ubc.ca

    2011-01-01

    Recent claims in the literature have suggested that the WMAP quadrupole is not primordial in origin, and arises from an aliasing of the much larger dipole field because of incorrect satellite pointing. We attempt to reproduce this result and delineate the key physics leading to the effect. We find that, even if real, the induced quadrupole would be smaller than the WMAP value. We discuss reasons why the WMAP data are unlikely to suffer from this particular systematic effect, including the implications for observations of point sources. Given this evidence against the reality of the effect, the similarity between the pointing-offset-induced signal and the actual quadrupole then appears to be quite puzzling. However, we find that the effect arises from a convolution between the gradient of the dipole field and anisotropic coverage of the scan direction at each pixel. There is something of a directional conspiracy here — the dipole signal lies close to the Ecliptic Plane, and its direction, together with the WMAP scan strategy, results in a strong coupling to the Y{sub 2,−1} component in Ecliptic co-ordinates. The dominant strength of this component in the measured quadrupole suggests that one should exercise increased caution in interpreting its estimated amplitude. The Planck satellite has a different scan strategy which does not so directly couple the dipole and quadrupole in this way and will soon provide an independent measurement.

  17. Quadrupole splitting and Eu partial lattice dynamics in europium orthophosphate EuPO 4

    NASA Astrophysics Data System (ADS)

    Klobes, B.; Arinicheva, Y.; Neumeier, S.; Simon, R. E.; Jafari, A.; Bosbach, D.; Hermann, R. P.

    2016-12-01

    Hyperfine interactions in europium orthophosphate EuPO4 were investigated using 151Eu Mössbauer spectroscopy from 6 to 300 K. The value of the quadrupole splitting and the asymmetry parameter were refined and further substantiated by nuclear forward scattering data obtained at room temperature. The temperature dependence of the relative absorption was modeled with an Eu specific Debye temperature of 221(1) K. Eu partial lattice dynamics were probed by means of nuclear inelastic scattering and the mean force constant, the Lamb-Mössbauer factor, the internal energy, the vibrational entropy, the average phonon group velocity were calculated using the extracted density of phonon states. In general, Eu specific vibrations are characterized by rather small phonon energies and contribute strongly to the total entropy of the system. Although there is no classical Debye like behavior at low vibrational energies, the average phonon group velocity can be reasonably approximated using a linear fit.

  18. How do nuclei really vibrate or rotate

    SciTech Connect

    Andresen, H.G.; Kunz, J.; Mosel, U.; Mueller, M.; Schuh, A.; Wust, U.

    1983-01-01

    By means of the adiabatic cranking model the properties of the current and velocity fields of nuclear quadrupole vibrations for even-even nuclei in the rare-earth region are investigated. BCS correlated wave functions based on the Nilsson single particle Hamiltonian have been used. The current fields are analyzed in terms of vector spherical harmonics. The realistic microscopic currents show a vortex structure not present in the classical irrotational flow. The microscopic origin of the vortex structure is investigated.

  19. Resonance methods in quadrupole ion traps

    NASA Astrophysics Data System (ADS)

    Snyder, Dalton T.; Peng, Wen-Ping; Cooks, R. Graham

    2017-01-01

    The quadrupole ion trap is widely used in the chemical physics community for making measurements on dynamical systems, both intramolecular (e.g. ion fragmentation reactions) and intermolecular (e.g. ion/molecule reactions). In this review, we discuss linear and nonlinear resonances in quadrupole ion traps, an understanding of which is critical for operation of these devices and interpretation of the data which they provide. The effect of quadrupole field nonlinearity is addressed, with important implications for promoting fragmentation and achieving unique methods of mass scanning. Methods that depend on ion resonances (i.e. matching an external perturbation with an ion's induced frequency of motion) are discussed, including ion isolation, ion activation, and ion ejection.

  20. The Large Quadrupole of Water Molecules

    SciTech Connect

    Niu, Shuqiang; Tan, Ming-Liang; Ichiye, Toshhiko

    2011-04-07

    Many quantum mechanical calculations indicate water molecules in the gas and liquid phase have much larger quadrupole moments than any of the common site models of water for computer simulations. Here, comparisons of multipoles from quantum mechanical/molecular mechanical (QM/MM) calculations at the MP2/aug-cc-pVQZ level on a B3LYP/aug-cc-pVQZ level geometry of a waterlike cluster and from various site models show that the increased square planar quadrupole can be attributed to the p-orbital character perpendicular to the molecular plane of the highest occupied molecular orbital as well as a slight shift of negative charge toward the hydrogens. The common site models do not account for the p-orbital type electron density and fitting partial charges of TIP4P- or TIP5P-type models to the QM/MM dipole and quadrupole give unreasonable higher moments. Furthermore, six partial charge sites are necessary to account reasonably for the large quadrupole, and polarizable site models will not remedy the problem unless they account for the p-orbital in the gas phase since the QM calculations show it is present there too. On the other hand, multipole models by definition can use the correct multipoles and the electrostatic potential from the QM/MM multipoles is much closer than that from the site models to the potential from the QM/MM electron density. Finally, Monte Carlo simulations show that increasing the quadrupole in the soft-sticky dipole-quadrupole-octupole multipole model gives radial distribution functions that are in good agreement with experiment

  1. Magnetic Measurement Results of the LCLS Undulator Quadrupoles

    SciTech Connect

    Anderson, Scott; Caban, Keith; Nuhn, Heinz-Dieter; Reese, Ed; Wolf, Zachary; /SLAC

    2011-08-18

    This note details the magnetic measurements and the magnetic center fiducializations that were performed on all of the thirty-six LCLS undulator quadrupoles. Temperature rise, standardization reproducibility, vacuum chamber effects and magnetic center reproducibility measurements are also presented. The Linac Coherent Light Source (LCLS) undulator beam line has 33 girders, each with a LCLS undulator quadrupole which focuses and steers the beam through the beam line. Each quadrupole has main quadrupole coils, as well as separate horizontal and vertical trim coils. Thirty-six quadrupoles, thirty-three installed and three spares were, manufactured for the LCLS undulator system and all were measured to confirm that they met requirement specifications for integrated gradient, harmonics and for magnetic center shifts after current changes. The horizontal and vertical dipole trims of each quadrupole were similarly characterized. Each quadrupole was also fiducialized to its magnetic center. All characterizing measurements on the undulator quads were performed with their mirror plates on and after a standardization of three cycles from -6 to +6 to -6 amps. Since the undulator quadrupoles could be used as a focusing or defocusing magnet depending on their location, all quadrupoles were characterized as focusing and as defocusing quadrupoles. A subset of the undulator quadrupoles were used to verify that the undulator quadrupole design met specifications for temperature rise, standardization reproducibility and magnetic center reproducibility after splitting. The effects of the mirror plates on the undulator quadrupoles were also measured.

  2. The nuclear electric quadrupole moment of copper.

    PubMed

    Santiago, Régis Tadeu; Teodoro, Tiago Quevedo; Haiduke, Roberto Luiz Andrade

    2014-06-21

    The nuclear electric quadrupole moment (NQM) of the (63)Cu nucleus was determined from an indirect approach by combining accurate experimental nuclear quadrupole coupling constants (NQCCs) with relativistic Dirac-Coulomb coupled cluster calculations of the electric field gradient (EFG). The data obtained at the highest level of calculation, DC-CCSD-T, from 14 linear molecules containing the copper atom give rise to an indicated NQM of -198(10) mbarn. Such result slightly deviates from the previously accepted standard value given by the muonic method, -220(15) mbarn, although the error bars are superimposed.

  3. An improved model electronic Hamiltonian for potential energy surfaces and spin−orbit couplings of low-lying d−d states of [Fe(bpy){sub 3}]{sup 2+}

    SciTech Connect

    Iuchi, Satoru Koga, Nobuaki

    2014-01-14

    With the aim of exploring excited state dynamics, a model electronic Hamiltonian for several low-lying d−d states of [Fe(bpy){sub 3}]{sup 2+} complex [S. Iuchi, J. Chem. Phys. 136, 064519 (2012)] is refined using density-functional theory calculations of singlet, triplet, and quintet states as benchmarks. Spin−orbit coupling elements are also evaluated within the framework of the model Hamiltonian. The accuracy of the developed model Hamiltonian is determined by examining potential energies and spin−orbit couplings at surface crossing regions between different spin states. Insights into the potential energy surfaces around surface crossing regions are also provided through molecular dynamics simulations. The results demonstrate that the constructed model Hamiltonian can be used for studies on the d−d excited state dynamics of [Fe(bpy){sub 3}]{sup 2+}.

  4. Nuclear quadrupole resonance studies in semi-metallic structures

    NASA Technical Reports Server (NTRS)

    Murty, A. N.

    1974-01-01

    Both experimental and theoretical studies are presented on spectrum analysis of nuclear quadrupole resonance of antimony and arsenic tellurides. Numerical solutions for secular equations of the quadrupole interaction energy are also discussed.

  5. Trade-offs in miniature quadrupole designs.

    PubMed

    Boumsellek, S; Ferran, R J

    2001-06-01

    Pressing needs for miniature mass spectrometers became apparent during the last decade in process monitoring and control, space exploration, and environmental screening. Besides the small footprint, common requirements include low cost, low power consumption, field portability, reliability, autonomy, and ease-of-use. Design concepts and construction technologies of miniaturized quadrupole sensors were guided by cost reduction requirements without sacrifice of performance. The first miniature and complete quadrupole mass spectrometer system was introduced as the Micropole sensor. The concept featured a novel technique to assemble and operate multiple miniature quadrupoles in parallel. The short analyzer length offers a significant advantage by enabling direct mass filtering at pressures up in the 10(-2) torr range. High voltages at higher frequencies (10-20 MHz) are required for acceptable mass resolving powers. Additional trade-offs were uncovered in miniature sensors leading to designs optimized for each class of applications. Real time ray tracing of ions injected and filtered in the quadrupole field is used early in the design stage to predict the performance and reliability of the device.

  6. Closed orbit response to quadrupole strength variation

    SciTech Connect

    Wolski, Andrzej; Zimmermann, Frank

    2004-01-20

    We derive two formulae relating the variation in closed orbit in a storage ring to variations in quadrupole strength, neglecting nonlinear and dispersive effects. These formulae correct results previously reported [1,2,3]. We compare the results of the formulae applied to the ATF with simulations using MAD, and consider their application to beam-based alignment.

  7. Thermal analysis of SC quadrupoles in accelerator interaction regions

    SciTech Connect

    Novitski, Igor; Zlobin, Alexander V.; /Fermilab

    2006-09-01

    This paper presents results of a thermal analysis and operation margin calculation performed for NbTi and Nb{sub 3}Sn low-beta quadrupoles in collider interaction regions. Results of the thermal analysis for NbTi quadrupoles are compared with the relevant experimental data. An approach to quench limit measurements for Nb{sub 3}Sn quadrupoles is discussed.

  8. Electrodynamical forbiddance of strong quadrupole light-molecule interaction and peculiarities of the SEHR spectra in the methane molecule

    NASA Astrophysics Data System (ADS)

    Chelibanov, V. P.; Polubotko, A. M.

    2014-07-01

    It is demonstrated that the strong quadrupole light-molecule interaction, which is responsible for the most enhancement of Surface Enhanced Hyper Raman Scattering (SEHRS), experiences so-called electrodynamical forbiddance in the methane molecule and molecules with cubic symmetry groups and does not influence on formation of the SEHRS spectra. This forbiddance results in the fact that the lines, caused by the totally symmetric vibrations, which are observed in pyrazine and phenazine, must be slight, or absent at all. In this case, in methane, the most enhanced lines are those, caused by vibrations, transforming after the irreducible representations T1 , or T2 .

  9. Femtosecond time-resolved spectroscopy of coherent vibrational and electronic excitations in solids

    NASA Astrophysics Data System (ADS)

    Williams*, Leah Ruby; Nelson, Keith A.

    1986-08-01

    ``Impulsive'' stimulated scattering (ISS) of femtosecond laser pulses was used to coherently excite and probe a low-lying (61-cm-1) electronic excitation in the cooperative Jahn-Teller crystal, terbium vanadate. Coherent terahertz oscillations and their dephasing were observed in the time domain. ISS is a general aspect of ultrashort-pulse interactions with matter, through which coherent excitations are produced whenever a sufficiently short laser pulse enters a Raman-active medium. Its use for measurement of vibrational and electronic dephasing and lifetimes, and for time-resolved spectroscopy of vibrationally distorted crystals and molecules, is discussed.

  10. Quadrupole deformation of electron shells in the lattice dynamics of compressed rare-gas crystals

    NASA Astrophysics Data System (ADS)

    Troitskaya, E. P.; Chabanenko, Val. V.; Zhikharev, I. V.; Gorbenko, Ie. Ie.; Pilipenko, E. A.

    2012-06-01

    The lattice dynamics of rare-gas crystals has been constructed taking into account the deformation of electron shells of the atoms of the dipole and quadrupole types, depending on the displacement of the nuclei. The obtained equations of lattice vibrations have been investigated in the long-wavelength approximation. The role played by the three-body interaction and the deformation of the electron shells in the violation of the Cauchy relation has been discussed. The calculated Birch elastic moduli for Xe and deviations from the Cauchy relation are in good agreement with the available experimental data over a wide range of pressures.

  11. Vibrational energy levels of CH5+

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Gang; Carrington, Tucker

    2008-12-01

    We present a parallelized contracted basis-iterative method for calculating numerically exact vibrational energy levels of CH5+ (a 12-dimensional calculation). We use Radau polyspherical coordinates and basis functions that are products of eigenfunctions of bend and stretch Hamiltonians. The bend eigenfunctions are computed in a nondirect product basis with more than 200×106 functions and the stretch functions are computed in a product potential optimized discrete variable basis. The basis functions have amplitude in all of the 120 equivalent minima. Many low-lying levels are well converged. We find that the energy level pattern is determined in part by the curvature and width of the valley connecting the minima and in part by the slope of the walls of this valley but does not depend on the height or shape of the barriers separating the minima.

  12. VIBRATION COMPACTION

    DOEpatents

    Hauth, J.J.

    1962-07-01

    A method of compacting a powder in a metal container is described including the steps of vibrating the container at above and below the resonant frequency and also sweeping the frequency of vibration across the resonant frequency several times thereby following the change in resonant frequency caused by compaction of the powder. (AEC)

  13. Vibration isolation

    NASA Technical Reports Server (NTRS)

    Bastin, Paul

    1990-01-01

    Viewgraphs on vibration isolation are presented. Techniques to control and isolate centrifuge disturbances were identified. Topics covered include: disturbance sources in the microgravity environment; microgravity assessment criteria; life sciences centrifuge; flight support equipment for launch; active vibration isolation system; active balancing system; and fuzzy logic control.

  14. Anharmonicities of nuclear vibrations from periodic mean-field orbits

    SciTech Connect

    Abada, A.; Vautherin, D. )

    1992-05-01

    A new method for constructing periodic orbits of the time-dependent Hartree-Fock equations is proposed. It is based on a perturbative expansion in the amplitude of the collective vibration. We present applications to the case of octupole vibrations in {sup 16}O and {sup 40}Ca. From calculations performed up to second order we determine the splitting of the two-phonon states. We discuss the problems which, for the quadrupole mode, arise from a resonant coupling of the vibration with states of the continuum.

  15. Quantum Monte Carlo for vibrating molecules

    SciTech Connect

    Brown, W.R. |

    1996-08-01

    Quantum Monte Carlo (QMC) has successfully computed the total electronic energies of atoms and molecules. The main goal of this work is to use correlation function quantum Monte Carlo (CFQMC) to compute the vibrational state energies of molecules given a potential energy surface (PES). In CFQMC, an ensemble of random walkers simulate the diffusion and branching processes of the imaginary-time time dependent Schroedinger equation in order to evaluate the matrix elements. The program QMCVIB was written to perform multi-state VMC and CFQMC calculations and employed for several calculations of the H{sub 2}O and C{sub 3} vibrational states, using 7 PES`s, 3 trial wavefunction forms, two methods of non-linear basis function parameter optimization, and on both serial and parallel computers. In order to construct accurate trial wavefunctions different wavefunctions forms were required for H{sub 2}O and C{sub 3}. In order to construct accurate trial wavefunctions for C{sub 3}, the non-linear parameters were optimized with respect to the sum of the energies of several low-lying vibrational states. In order to stabilize the statistical error estimates for C{sub 3} the Monte Carlo data was collected into blocks. Accurate vibrational state energies were computed using both serial and parallel QMCVIB programs. Comparison of vibrational state energies computed from the three C{sub 3} PES`s suggested that a non-linear equilibrium geometry PES is the most accurate and that discrete potential representations may be used to conveniently determine vibrational state energies.

  16. Seawater-overwash impacts on freshwater-lens water supplies of low-lying oceanic islands: example from Roi-Namur Island, Kwajalein Atoll, Republic of the Marshall Islands

    NASA Astrophysics Data System (ADS)

    Voss, C. I.; Gingerich, S. B.

    2015-12-01

    Low-lying oceanic islands host thin freshwater lenses subject to long-term aquifer salinization by seawater overwash. The lens is often the sole-source water supply for inhabitants. As maximum elevation for these islands is only a few meters above sea level, overwash can occur during high tides and storm surges. Sea level rise due to climate change will make overwash events even more common. The thin freshwater lenses, a few meters thick, are underlain by seawater, so pumping must be done carefully, often with horizontal skimming wells. Even a small amount of downward seawater infiltration from an overwash event can render the water supply non-potable. Where permeability is high, seawater infiltrates quickly, but seawater that infiltrates lower-permeability zones may remain for many months causing groundwater to remain non-potable, leaving residents without a reliable freshwater source. Initial post-overwash salinization is driven by the higher density of the invading saltwater, which sinks and mixes into the fresher water in potentially-complex patterns determined by: distribution of flooding and post-flood ponding, locations of permeable paths, and the inherently complex flow fields generated when fluid of higher density overlies lower-density fluid. The flow patterns cannot generally be measured or predicted in detail. This study develops basic understanding of overwash salinization processes impacting water supply on low-level islands, using a rare example of a monitored seawater overwash event that occurred in December 2008 at Roi-Namur Island in Kwajalein Atoll, Republic of the Marshall Islands, in which the salinity evolution of well water was measured. Due to typical lack of field data on such islands, a set of plausible alternative simulation-model descriptions of the hydrogeology and overwash event are created for analysis of the monitored salinization and recovery. Despite inability to know the 'true and complete' description of the event and the

  17. Revelation of non-statistical behavior in HO2 vibration by a new ab initio potential energy surface.

    PubMed

    Lin, Shi Ying; Xie, Daiqian; Guo, Hua

    2006-09-07

    The hydroperoxyl radical (HO2) has long been considered as a prototype for statistical vibrational dynamics. In this work, however, it is shown that the bound state energy levels (up to the dissociation threshold) and low-lying resonances of the HO2 system (J=0) obtained on a new ab initio potential energy surface exhibit surprisingly large regularity. The implications of the non-statistical behavior of the HO2 system in unimolecular and bimolecular reactions are discussed.

  18. LARP Long Nb3Sn Quadrupole Design.

    SciTech Connect

    Ambrosio,G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Caspi, S.; Chlachidize, G.; Dietderich, D.; Feher, S.; Felice, H.; Ferracin, P.; Ghosh, A.; Hafalia, A.R.; Hannaford, C.R.; Kashikhin, V.V.; Kerby, J.; Lamm, M.; Lietzke, A.; McInturff, A.; Muratore, J.; Nobrega, F.; Novitsky, I.; Sabbi, G.L.; Schmalzle, J.; Tartaglia, M.; Turrioni, D.; Wanderer, P.; Whitson, G.; Zlobin, A.V.

    2007-08-27

    A major milestone for the LHC Accelerator Research Program (LARP) is the test, by the end of 2009, of two 4m-long quadrupole magnets (LQ) wound with Nb{sub 3}Sn conductor. The goal of these magnets is to be a proof of principle that Nb{sub 3}Sn is a viable technology for a possible LHC luminosity upgrade. The design of the LQ is based on the design of the LARP Technological Quadrupoles, presently under development at FNAL and LBNL, with 90-mm aperture and gradient higher than 200 T/m. The design of the first LQ model will be completed by the end of 2007 with the selection of a mechanical design. In this paper we present the coil design addressing some fabrication technology issues, the quench protection study, and three designs of the support structure.

  19. LARP Long Nb3Sn Quadrupole Design

    SciTech Connect

    Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Caspi, S.; Chlachidize, G.; Dietderich, D.; Feher, S.; Ferracin, P.; Ghosh, A.; Hafalia, R.; Hannaford, R.; Kashikhin, V.V.; Kerby, J.; Lamm, M.; Lietzke, A.; McInturff, A.; Muratore, J.; Nobrega, F.; Novitsky, I.; Sabbi, G.L.; Schmalzle, J.; Tartaglia, M.; Turrioni, D.; Wanderer, P.; Whitson, G.; Zlobin, A.V.

    2008-06-01

    A major milestone for the LHC Accelerator Research Program (LARP) is the test, by the end of 2009, of two 4m-long quadrupole magnets (LQ) wound with Nb{sub 3}Sn conductor. The goal of these magnets is to be a proof of principle that Nb{sub 3}Sn is a viable technology for a possible LHC luminosity upgrade. The design of the LQ is based on the design of the LARP Technological Quadrupoles, presently under development at FNAL and LBNL, with 90-mm aperture and gradient higher than 200 T/m. The design of the first LQ model will be completed by the end of 2007 with the selection of a mechanical design. In this paper we present the coil design addressing some fabrication technology issues, the quench protection study, and three designs of the support structure.

  20. Permanent-magnet quadrupoles in RFQ Linacs

    SciTech Connect

    Lysenko, W.P.; Wang, T.F.

    1985-10-01

    We investigated the possibility of increasing the current-carrying capability of radio-frequency quadrupole (RFQ) linear accelerators by adding permanentmagnet quadrupole (PMQ) focusing to the existing transverse focusing provided by the rf electric field. Increased transverse focusing would also allow shortening RFQ linacs by permitting a larger accelerating gradient, which is normally accompanied by an undesirable increased transverse rf defocusing effect. We found that PMQs were not helpful in increasing the transverse focusing strength in an RFQ. This conclusion was reached after some particle tracing simulations and some analytical calculations. In our parameter regime, the addition of the magnets increases the betatron frequency but does not result in improved focusing because the increased flutter more than offsets the gain from the increased betatron frequency.

  1. LARP Long Nb3Sn Quadrupole Design

    SciTech Connect

    Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bossert, R.; Caspi, S.; Chlachidze, G.; Dietderich, D.; Feher, S.; Felice, H.; Ferracin, P.; /Fermilab /Brookhaven /LBL, Berkeley /Texas A-M

    2007-08-01

    A major milestone for the LHC Accelerator Research Program (LARP) is the test, by the end of 2009, of two 4m-long quadrupole magnets (LQ) wound with Nb3Sn conductor. The goal of these magnets is to be a proof of principle that Nb3Sn is a viable technology for a possible LHC luminosity upgrade. The design of the LQ is based on the design of the LARP Technological Quadrupoles, presently under development at FNAL and LBNL, with 90-mm aperture and gradient higher than 200 T/m. The design of the first LQ model will be completed by the end of 2007 with the selection of a mechanical design. In this paper we present the coil design addressing some fabrication technology issues, the quench protection study, and three designs of the support structure.

  2. Modal response of 4-rod type radio frequency quadrupole linac

    SciTech Connect

    Chatterjee, Avik; Mahapatra, Abhijit; Mondal, Manas; Chakrabarti, Alok

    2009-10-15

    This paper deals with the analysis and experimental study of natural frequencies of vibration of a 4-rod type radio frequency quadrupole (RFQ) linear accelerator. The eigenvalue analysis of the structure has been done both analytically (multispan beam concept) as well as using blocked Lanczos eigenvalue finite element solver with an ability to extract the rigid body modes. This has been done in the mechanical design phase to find the level of agreement between the output of simplified analytical analysis results and the output of a commercial finite element method (FEM) solver, since a full scale RFQ structure is too complex to handle analytically. Experimental validation of the analysis results has been done on the physical 1.7 m RFQ at the installation site. The experimental data obtained were later analyzed and found to be in close agreement with the predicted frequencies in the lower frequency ranges. It gets more and more deviated in the higher frequency ranges. Also some frequencies were observed during experimentation, which were not found in the finite element analysis results. The source of those frequencies are to be further investigated as it may play a predominant role in the design high quality factor beam line cavities for higher operational efficiency.

  3. Electric Quadrupole Transition Measurements of Hydrogen Molecule with High Precision

    NASA Astrophysics Data System (ADS)

    Cheng, Cun-Feng; Wang, Jin; Tan, Yan; Liu, An-Wen; Hu, Shui-Ming

    2013-06-01

    Molecular hydrogen is the most fundamental, and the only neutral molecule expected to be both calculated and measured with extremely high accuracy. High-precision measurements of its spectroscopy, especially the levels at the electric ground state, play an important role in the examination of precise quantum chemistry calculations and some fundamental physical constants. In the infrared region, H_2, being a homonuclear diatomic molecule, only has very weak electric quadrupole transitions. We established a new spectroscopy approach with ultra-high precision and sensitivity as well, based on a laser-locked cavity ring-down spectrometer. An equivalent absorption path-length of thousands of kilometers and a frequency precision of 10^{-5} cm^{-1} have been achieved. Ro-vibrational spectra of the second overtone of H_2 have been recorded. The obtained results will provide a direct examination of the high-accuracy quantum theory. It also shades light on the determination of fundamental physical constants such as the electron/proton mass ratio in a molecular system.

  4. Modal response of 4-rod type radio frequency quadrupole linac.

    PubMed

    Chatterjee, Avik; Mahapatra, Abhijit; Mondal, Manas; Chakrabarti, Alok

    2009-10-01

    This paper deals with the analysis and experimental study of natural frequencies of vibration of a 4-rod type radio frequency quadrupole (RFQ) linear accelerator. The eigenvalue analysis of the structure has been done both analytically (multispan beam concept) as well as using blocked Lanczos eigenvalue finite element solver with an ability to extract the rigid body modes. This has been done in the mechanical design phase to find the level of agreement between the output of simplified analytical analysis results and the output of a commercial finite element method (FEM) solver, since a full scale RFQ structure is too complex to handle analytically. Experimental validation of the analysis results has been done on the physical 1.7 m RFQ at the installation site. The experimental data obtained were later analyzed and found to be in close agreement with the predicted frequencies in the lower frequency ranges. It gets more and more deviated in the higher frequency ranges. Also some frequencies were observed during experimentation, which were not found in the finite element analysis results. The source of those frequencies are to be further investigated as it may play a predominant role in the design high quality factor beam line cavities for higher operational efficiency.

  5. Quadrupole stellar oscillations: The impact of gravitational waves from the Galactic Center

    NASA Astrophysics Data System (ADS)

    Lopes, Ilídio

    2017-06-01

    Acoustic quadrupole modes of sunlike stars vibrate when perturbed by a passing gravitational wave generated somewhere in the Universe. Here, we compute the imprint of the gravitational waves on the acoustic spectrum of these stars for gravitational events occurring near the supermassive black hole located at the center of the Milky Way. We found that in most cases the impact of gravitational waves in low-order quadrupole modes is not above the current observational threshold of detectability, although this should be in the reach of the next generation of near infrared observatories and asteroseismology satellite missions. Equally, we found that it is possible to follow the end phase of the coalescence of binaries with large chirp masses, as these phenomena have a unique imprint in the spectra of sunlike stars affecting sequentially several low-order quadrupole modes. Moreover, we discuss the different imprints on the acoustic spectra of the different types of binary systems constituted either by two white dwarfs, two neutron stars, two black holes or a compact star and a massive black hole.

  6. Temperature dependence of the quadrupole interaction of69Ge Tl and113Sn Sn

    NASA Astrophysics Data System (ADS)

    Semmler, W.; Raghavan, P.; Senba, M.; Raghavan, R. S.

    1981-03-01

    The quadrupole interaction constants of69Ge T1 and113Sn Sn were measured by means of the perturbed angular distribution technique as a function of temperature in the range of 80K≦T≦508 K and 80K≦T≦480 K, respectively. Isomeric states in69Ge and113Sn were populated by the heavy ion reactions56Fe(16O, 2 p n) and100Mo(16O, 3 n) and recoil implanted into polycrystalline Tl- and single crystalline Sn-backings. In the case of113Sn Sn, where the quadrupole coupling is weak, a special single crystal geometry was employed to enhance the sensitivity of the measurement. Within the limits of the errors the temperature dependence for both systems follows the empirical T1.5-dependence. While a strong temperature dependence comparable to In In is observed for69Ge T1, that for113Sn Sn is weaker than expected. The strength of the temperature dependence for113Sn Sn does not agree with the predictions of a lattice vibration model proposed recently for the temperature dependence of the quadrupole interaction.

  7. Radio frequency quadrupole resonator for linear accelerator

    DOEpatents

    Moretti, Alfred

    1985-01-01

    An RFQ resonator for a linear accelerator having a reduced level of interfering modes and producing a quadrupole mode for focusing, bunching and accelerating beams of heavy charged particles, with the construction being characterized by four elongated resonating rods within a cylinder with the rods being alternately shorted and open electrically to the shell at common ends of the rods to provide an LC parallel resonant circuit when activated by a magnetic field transverse to the longitudinal axis.

  8. Electrostatic quadrupole DC accelerators for BNCT applications

    SciTech Connect

    Kwan, J.W.; Anderson, O.A.; Reginato, L.L.; Vella, M.C.; Yu, S.S.

    1994-04-01

    A dc electrostatic quadrupole (ESQ) accelerator is capable of producing a 2.5 MeV, 100 mA proton beam for the purpose of generating neutrons for Boron Neutron Capture Therapy. The ESQ accelerator is better than the conventional aperture column in high beam current application due to the presence of stronger transverse field for beam focusing and for suppressing secondary electrons. The major challenge in this type of accelerator is in developing the proper power supply system.

  9. Muon cooling in a quadrupole magnet channel

    SciTech Connect

    Neuffer, David; Poklonskiy, A.; /Michigan State U.

    2007-10-01

    As discussed before,[1] a cooling channel using quadrupole magnets in a FODO transport channel can be used for initial cooling of muons. In the present note we discuss this possibility of a FODO focusing channel for cooling, and we present ICOOL simulations of muon cooling within a FODO channel. We explore a 1.5m cell-length cooling channel that could be used for the initial transverse cooling stage of a muon collider or neutrino factory.

  10. Superconducting quadrupoles for the SLC final focus

    SciTech Connect

    Erickson, R.; Fieguth, T.; Murray, J.J.

    1987-01-01

    The final focus system of the SLC will be upgraded by replacing the final quadrupoles with higher gradient superconducting magnets positioned closer to the interaction point. The parameters of the new system have been chosen to be compatible with the experimental detectors with a minimum of changes to other final focus components. These parameter choices are discussed along with the expected improvement in SLC performance.

  11. 15 T And Beyond - Dipoles and Quadrupoles

    SciTech Connect

    Sabbi, GianLuca

    2008-05-19

    Starting with the invention of the cyclotron by Lawrence, accelerator-based experiments have been the primary source of new discoveries in particle physics. In order to progress toward higher energy and luminosity, higher field magnets are required. R&D programs are underway to take advantage of new developments in superconducting materials, achieve better efficiency and simplify magnet fabrication while preserving accelerator-class field quality. A review of recent progress on high field dipole and quadrupole magnets is presented.

  12. Quadrupole transitions revealed by Borrmann spectroscopy.

    PubMed

    Pettifer, Robert F; Collins, Stephen P; Laundy, David

    2008-07-10

    The Borrmann effect-a dramatic increase in transparency to X-ray beams-is observed when X-rays satisfying Bragg's law diffract through a perfect crystal. The minimization of absorption seen in the Borrmann effect has been explained by noting that the electric field of the X-ray beam approaches zero amplitude at the crystal planes, thus avoiding the atoms. Here we show experimentally that under conditions of absorption suppression, the weaker electric quadrupole absorption transitions are effectively enhanced to such a degree that they can dominate the absorption spectrum. This effect can be exploited as an atomic spectroscopy technique; we show that quadrupole transitions give rise to additional structure at the L(1), L(2) and L(3) absorption edges of gadolinium in gadolinium gallium garnet, which mark the onset of excitations from 2s, 2p(1/2) and 2p(3/2) atomic core levels, respectively. Although the Borrmann effect served to underpin the development of the theory of X-ray diffraction, this is potentially the most important experimental application of the phenomenon since its first observation seven decades ago. Identifying quadrupole features in X-ray absorption spectroscopy is central to the interpretation of 'pre-edge' spectra, which are often taken to be indicators of local symmetry, valence and atomic environment. Quadrupolar absorption isolates states of different symmetries to that of the dominant dipole spectrum, and typically reveals orbitals that dominate the electronic ground-state properties of lanthanides and 3d transition metals, including magnetism. Results from our Borrmann spectroscopy technique feed into contemporary discussions regarding resonant X-ray diffraction and the nature of pre-edge lines identified by inelastic X-ray scattering. Furthermore, because the Borrmann effect has been observed in photonic materials, it seems likely that the quadrupole enhancement reported here will play an important role in modern optics.

  13. Table of nuclear electric quadrupole moments

    NASA Astrophysics Data System (ADS)

    Stone, N. J.

    2016-09-01

    This Table is a compilation of experimental measurements of static electric quadrupole moments of ground states and excited states of atomic nuclei throughout the periodic table. To aid identification of the states, their excitation energy, half-life, spin and parity are given, along with a brief indication of the method and any reference standard used in the particular measurement. Experimental data from all quadrupole moment measurements actually provide a value of the product of the moment and the electric field gradient [EFG] acting at the nucleus. Knowledge of the EFG is thus necessary to extract the quadrupole moment. A single recommended moment value is given for each state, based, for each element, wherever possible, upon a standard reference moment for a nuclear state of that element studied in a situation in which the electric field gradient has been well calculated. For several elements one or more subsidiary EFG/moment reference is required and their use is specified. The literature search covers the period to mid-2015.

  14. Structures, energetics and vibrational spectra of (H2O)32 clusters: a journey from model potentials to correlated theory

    NASA Astrophysics Data System (ADS)

    Sahu, Nityananda; Khire, Subodh S.; Gadre, Shridhar R.

    2015-10-01

    Empirical model potentials are found to be very useful for generating most competitive minima of large water clusters, whereas correlated (e.g. second order-Møller-Plesset perturbation (MP2) theory or higher) calculations are necessary for predicting their accurate energetics and vibrational features. The present study reports the structures and energetics of (H2O)32 clusters at MP2 level using aug-cc-pvDZ basis set, starting with low-lying structures generated from model potentials. Such high-end and accurate calculations are made feasible by the cost-effective fragment-based molecular tailoring approach (MTA) in conjunction with the grafting procedure. The latter is found to yield electronic energies with a sub-millihartree accuracy with reference to their full calculation counterparts. The vibrational spectra of nine low-lying (H2O)32 isomers are obtained from the corresponding MTA-based Hessian matrix. All these low-lying isomers show almost similar spectral features, which are in fair agreement with the experiment. The experimental spectrum of (H2O)32 is thus better understood from the vibrational features of this set of very closely spaced isomers. The present case study of (H2O)32 clearly demonstrates the efficacy in obtaining accurate structures, energetics and spectra at correlated level of theory by combining model potential-based structures with fragmentation methods.

  15. Nanosecond lifetime measurements of Iπ=9/2- intrinsic excited states and low-lying B(E1) strengths in 183Re using combined HPGe-LaBr3 coincidence spectroscopy

    NASA Astrophysics Data System (ADS)

    Gurgi, L. A.; Regan, P. H.; Daniel, T.; Podolyák, Zs.; Bruce, A. M.; Mason, P. J. R.; Mǎrginean, N.; Mǎrginean, R.; Werner, V.; Alharbi, T.; Alkhomashi, N.; Bajoga, A. D.; Britton, R.; Cǎta-Danil, I.; Carroll, R. J.; Deleanu, D.; Bucurescu, D.; Florea, N.; Gheorghe, I.; Ghita, D. G.; Glodariu, T.; Lice, R.; Mihai, C.; Mulholland, K. F.; Negret, A.; Olacel, A.; Roberts, O. J.; Sava, T.; Söderström, P.-A.; Stroe, L.; Suvaila, R.; Toma, S.; Wilson, E.; Wood, R. T.

    2017-08-01

    This paper presents precision measurements of electromagnetic decay probabilities associated with electric dipole transitions in the prolate-deformed nucleus 183Re. The nucleus of interest was formed using the fusion evaporation reaction 180Hf(7Li,4n)183Re at a beam energy of 30 MeV at the tandem accelerator at the HH-IFIN Institute, Bucharest Romania. Coincident decay gamma rays from near-yrast cascades were detected using the combined HPGe-LaBr3 detector array ROSPHERE. The time differences between cascade gamma rays were measured using the LaBr3 detectors to determine the half-lives of the two lowest lying spin-parity 9/2- states at excitation energies of 496 and 617 keV to be 5.65(5) and 2.08(3) ns respectively. The deduced E1 transition rates from these two states are discussed in terms of the K-hindrance between the low-lying structures in this prolate-deformed nucleus.

  16. Assessing the impacts of sea-level rise and precipitation change on the surficial aquifer in the low-lying coastal alluvial plains and barrier islands, east-central Florida (USA)

    NASA Astrophysics Data System (ADS)

    Xiao, Han; Wang, Dingbao; Hagen, Scott C.; Medeiros, Stephen C.; Hall, Carlton R.

    2016-11-01

    A three-dimensional variable-density groundwater flow and salinity transport model is implemented using the SEAWAT code to quantify the spatial variation of water-table depth and salinity of the surficial aquifer in Merritt Island and Cape Canaveral Island in east-central Florida (USA) under steady-state 2010 hydrologic and hydrogeologic conditions. The developed model is referred to as the `reference' model and calibrated against field-measured groundwater levels and a map of land use and land cover. Then, five prediction/projection models are developed based on modification of the boundary conditions of the calibrated `reference' model to quantify climate change impacts under various scenarios of sea-level rise and precipitation change projected to 2050. Model results indicate that west Merritt Island will encounter lowland inundation and saltwater intrusion due to its low elevation and flat topography, while climate change impacts on Cape Canaveral Island and east Merritt Island are not significant. The SEAWAT models developed for this study are useful and effective tools for water resources management, land use planning, and climate-change adaptation decision-making in these and other low-lying coastal alluvial plains and barrier island systems.

  17. An assessment of low-lying excitation energies and triplet instabilities of organic molecules with an ab initio Bethe-Salpeter equation approach and the Tamm-Dancoff approximation.

    PubMed

    Rangel, Tonatiuh; Hamed, Samia M; Bruneval, Fabien; Neaton, Jeffrey B

    2017-05-21

    The accurate prediction of singlet and triplet excitation energies is an area of intense research of significant fundamental interest and critical for many applications. Most calculations of singlet and triplet energies use time-dependent density functional theory (TDDFT) in conjunction with an approximate exchange-correlation functional. In this work, we examine and critically assess an alternative method for predicting low-lying neutral excitations with similar computational cost, the ab initio Bethe-Salpeter equation (BSE) approach, and compare results against high-accuracy wavefunction-based methods. We consider singlet and triplet excitations of 27 prototypical organic molecules, including members of Thiel's set, the acene series, and several aromatic hydrocarbons exhibiting charge-transfer-like excitations. Analogous to its impact in TDDFT, we find that the Tamm-Dancoff approximation (TDA) overcomes triplet instabilities in the BSE approach, improving both triplet and singlet energetics relative to higher level theories. Finally, we find that BSE-TDA calculations built on effective DFT starting points, such as those utilizing optimally tuned range-separated hybrid functionals, can yield accurate singlet and triplet excitation energies for gas-phase organic molecules.

  18. An assessment of low-lying excitation energies and triplet instabilities of organic molecules with an ab initio Bethe-Salpeter equation approach and the Tamm-Dancoff approximation

    NASA Astrophysics Data System (ADS)

    Rangel, Tonatiuh; Hamed, Samia M.; Bruneval, Fabien; Neaton, Jeffrey B.

    2017-05-01

    The accurate prediction of singlet and triplet excitation energies is an area of intense research of significant fundamental interest and critical for many applications. Most calculations of singlet and triplet energies use time-dependent density functional theory (TDDFT) in conjunction with an approximate exchange-correlation functional. In this work, we examine and critically assess an alternative method for predicting low-lying neutral excitations with similar computational cost, the ab initio Bethe-Salpeter equation (BSE) approach, and compare results against high-accuracy wavefunction-based methods. We consider singlet and triplet excitations of 27 prototypical organic molecules, including members of Thiel's set, the acene series, and several aromatic hydrocarbons exhibiting charge-transfer-like excitations. Analogous to its impact in TDDFT, we find that the Tamm-Dancoff approximation (TDA) overcomes triplet instabilities in the BSE approach, improving both triplet and singlet energetics relative to higher level theories. Finally, we find that BSE-TDA calculations built on effective DFT starting points, such as those utilizing optimally tuned range-separated hybrid functionals, can yield accurate singlet and triplet excitation energies for gas-phase organic molecules.

  19. Photoassociation of a cold-atom-molecule pair: Long-range quadrupole-quadrupole interactions

    SciTech Connect

    Lepers, M.; Dulieu, O.; Kokoouline, V.

    2010-10-15

    The general formalism of the multipolar expansion of electrostatic interactions is applied to the calculation of the potential energy between an excited atom (without fine structure) and a ground-state diatomic molecule at large mutual separations. Both partners exhibit a permanent quadrupole moment so that their mutual long-range interaction is dominated by a quadrupole-quadrupole term, which is attractive enough to bind trimers. Numerical results are given for an excited Cs(6{sup 2}P) atom and a ground-state Cs{sub 2} molecule. The prospects for achieving photoassociation of a cold-atom-dimer pair are thus discussed and found promising. The formalism can be generalized to the long-range interaction between molecules to investigate the formation of cold tetramers.

  20. Vibrational Diver

    NASA Astrophysics Data System (ADS)

    Kozlov, Victor; Ivanova, Alevtina; Schipitsyn, Vitalii; Stambouli, Moncef

    2014-10-01

    The paper is concerned with dynamics of light solid in cavity with liquid subjected to rotational vibration in the external force field. New vibrational phenomenon - diving of a light cylinder to the cavity bottom is found. The experimental investigation of a horizontal annulus with a partition has shown that under vibration a light body situated in the upper part of the layer is displaced in a threshold manner some distance away from the boundary. In this case the body executes symmetric tangential oscillations. An increase of the vibration intensity leads to a tangential displacement of the body near the external boundary. This displacement is caused by the tangential component of the vibrational lift force, which appears as soon as the oscillations lose symmetry. In this case the trajectory of the body oscillatory motion has the form of a loop. The tangential lift force makes stable the position of the body on the inclined section of the layer and even in its lower part. A theoretical interpretation has been proposed, which explains stabilization of a quasi-equilibrium state of a light body near the cavity bottom in the framework of vibrational hydromechanics.

  1. Full-dimensional quantum calculations of vibrational levels of NH4+ and isotopomers on an accurate ab initio potential energy surface

    DOE PAGES

    Hua -Gen Yu; Han, Huixian; Guo, Hua

    2016-03-29

    Vibrational energy levels of the ammonium cation (NH4+) and its deuterated isotopomers are calculated using a numerically exact kinetic energy operator on a recently developed nine-dimensional permutation invariant semiglobal potential energy surface fitted to a large number of high-level ab initio points. Like CH4, the vibrational levels of NH4+ and ND4+ exhibit a polyad structure, characterized by a collective quantum number P = 2(v1 + v3) + v2 + v4. As a result, the low-lying vibrational levels of all isotopomers are assigned and the agreement with available experimental data is better than 1 cm–1.

  2. Full-Dimensional Quantum Calculations of Vibrational Levels of NH4(+) and Isotopomers on An Accurate Ab Initio Potential Energy Surface.

    PubMed

    Yu, Hua-Gen; Han, Huixian; Guo, Hua

    2016-04-14

    Vibrational energy levels of the ammonium cation (NH4(+)) and its deuterated isotopomers are calculated using a numerically exact kinetic energy operator on a recently developed nine-dimensional permutation invariant semiglobal potential energy surface fitted to a large number of high-level ab initio points. Like CH4, the vibrational levels of NH4(+) and ND4(+) exhibit a polyad structure, characterized by a collective quantum number P = 2(v1 + v3) + v2 + v4. The low-lying vibrational levels of all isotopomers are assigned and the agreement with available experimental data is better than 1 cm(-1).

  3. Nuclear vibrations and rotations of like nucleons in the same shell in even-even nuclei

    SciTech Connect

    Osman, A.; Allam, M.A.

    1987-01-01

    The vibrational and rotational motions in even nuclei are considered. A microscopic study of these motions leads to a relation between the vibrational motion in spherical nuclei and the rotational motion in deformed nuclei. Nuclei with like nucleons in the same shell are considered. The quadrupole two-body interactions are used in the large single j-shell of even nuclei. The energies and transition operators of nuclei in the nuclear rotational region are calculated using this microscopic method. Quadrupole moments are also calculated. These calculations are compared with the rotational model of the aligned coupling scheme. The present calculations are in good agreement with previous calculations.

  4. Ab initio correlated calculations of rare-gas dimer quadrupoles

    NASA Astrophysics Data System (ADS)

    Donchev, Alexander G.

    2007-10-01

    This paper reports ab initio calculations of rare gas ( RG=Kr , Ar, Ne, and He) dimer quadrupoles at the second order of Møller-Plesset perturbation theory (MP2). The study reveals the crucial role of the dispersion contribution to the RG2 quadrupole in the neighborhood of the equilibrium dimer separation. The magnitude of the dispersion quadrupole is found to be much larger than that predicted by the approximate model of Hunt. As a result, the total MP2 quadrupole moment is significantly smaller than was assumed in virtually all previous related studies. An analytical model for the distance dependence of the RG2 quadrupole is proposed. The model is based on the effective-electron approach of Jansen, but replaces the original Gaussian approximation to the electron density in an RG atom by an exponential one. The role of the nonadditive contribution in RG3 quadrupoles is discussed.

  5. Nuclear electric quadrupole interactions in liquids entrapped in cavities

    NASA Astrophysics Data System (ADS)

    Furman, Gregory B.; Meerovich, Victor M.; Sokolovsky, Vladimir L.

    2016-12-01

    Liquids entrapped in cavities and containing quadrupole nuclei are considered. The interaction of the quadrupole moment of a nucleus with the electric field gradient is studied. In such a system, molecules are in both rotational and translational Brownian motions which are described by the diffusion equation. Solving this equation, we show that the intra- and intermolecular nuclear quadrupole interactions are averaged to zero in cavities with the size larger than several angstroms.

  6. Random Vibrations

    NASA Technical Reports Server (NTRS)

    Messaro. Semma; Harrison, Phillip

    2010-01-01

    Ares I Zonal Random vibration environments due to acoustic impingement and combustion processes are develop for liftoff, ascent and reentry. Random Vibration test criteria for Ares I Upper Stage pyrotechnic components are developed by enveloping the applicable zonal environments where each component is located. Random vibration tests will be conducted to assure that these components will survive and function appropriately after exposure to the expected vibration environments. Methodology: Random Vibration test criteria for Ares I Upper Stage pyrotechnic components were desired that would envelope all the applicable environments where each component was located. Applicable Ares I Vehicle drawings and design information needed to be assessed to determine the location(s) for each component on the Ares I Upper Stage. Design and test criteria needed to be developed by plotting and enveloping the applicable environments using Microsoft Excel Spreadsheet Software and documenting them in a report Using Microsoft Word Processing Software. Conclusion: Random vibration liftoff, ascent, and green run design & test criteria for the Upper Stage Pyrotechnic Components were developed by using Microsoft Excel to envelope zonal environments applicable to each component. Results were transferred from Excel into a report using Microsoft Word. After the report is reviewed and edited by my mentor it will be submitted for publication as an attachment to a memorandum. Pyrotechnic component designers will extract criteria from my report for incorporation into the design and test specifications for components. Eventually the hardware will be tested to the environments I developed to assure that the components will survive and function appropriately after exposure to the expected vibration environments.

  7. Noise reduction in negative-ion quadrupole mass spectrometry

    DOEpatents

    Chastagner, Philippe

    1993-01-01

    A quadrupole mass spectrometer (QMS) system having an ion source, quadrupole mass filter, and ion collector/recorder system. A weak, transverse magnetic field and an electron collector are disposed between the quadrupole and ion collector. When operated in negative ion mode, the ion source produces a beam of primarily negatively-charged particles from a sample, including electrons as well as ions. The beam passes through the quadrupole and enters the magnetic field, where the electrons are deflected away from the beam path to the electron collector. The negative ions pass undeflected to the ion collector where they are detected and recorded as a mass spectrum.

  8. Noise reduction in negative-ion quadrupole mass spectrometry

    DOEpatents

    Chastagner, P.

    1993-04-20

    A quadrupole mass spectrometer (QMS) system is described having an ion source, quadrupole mass filter, and ion collector/recorder system. A weak, transverse magnetic field and an electron collector are disposed between the quadrupole and ion collector. When operated in negative ion mode, the ion source produces a beam of primarily negatively-charged particles from a sample, including electrons as well as ions. The beam passes through the quadrupole and enters the magnetic field, where the electrons are deflected away from the beam path to the electron collector. The negative ions pass undeflected to the ion collector where they are detected and recorded as a mass spectrum.

  9. Magnetic mirror structure for testing shell-type quadrupole coils

    SciTech Connect

    Andreev, N.; Barzi, E.; Bossert, R.; Chlachidze, G.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.; Tartaglia, N.; Turrioni, D.; /Fermilab

    2009-10-01

    This paper presents magnetic and mechanical designs and analyses of the quadrupole mirror structure to test single shell-type quadrupole coils. Several quadrupole coils made of different Nb{sub 3}Sn strands, cable insulation and pole materials were tested using this structure at 4.5 and 1.9 K. The coils were instrumented with voltage taps, spot heaters, temperature sensors and strain gauges to study their mechanical and thermal properties and quench performance. The results of the quadrupole mirror model assembly and test are reported and discussed.

  10. The Microwave Spectroscopy of Aminoacetonitrile in the Vibrational Excited States 2

    NASA Astrophysics Data System (ADS)

    Fujita, Chiho; Higurashi, Haruka; Ozeki, Hiroyuki; Kobayashi, Kaori

    2016-06-01

    Aminoacetonitrile (NH_2CH_2CN) is a potential precursor of the simplest amino acid, glycine in the interstellar space and was detected toward SgrB2(N). We have extended measurements up to 1.3 THz so that the strongest transitions that may be found in the terahertz region should be covered. Aminoacetonitrile has a few low-lying vibrational excited states and indeed the pure rotational transitions in these vibrational excited states were found. The pure rotational transitions in six vibrational excited states in the 80-180 GHz range have been assigned and centrifugal distortion constants up to the sextic terms were determined. Based on spectral intensities and the vibrational information from Bak et al., They were assigned to the 3 low-lying fundamentals, 1 overtone and 2 combination bands. In the submillimeter wavelength region, perturbations were recognized and some of the lines were off by more than a few MHz. At this moment, these perturbed transitions are not included in our analysis. A. Belloche, K. M. Menten, C. Comito, H. S. P. Müller, P. Schilke, J. Ott, S. Thorwirth, and C. Hieret, 2008, Astronom. & Astrophys. 482, 179 (2008). Y. Motoki, Y. Tsunoda, H. Ozeki, and K. Kobayashi, Astrophys. J. Suppl. Ser. 209, 23 (2013). B. Bak, E. L. Hansen, F. M. Nicolaisen, and O. F. Nielsen, Can. J. Phys. 53, 2183 (1975) C. Fujita, H. Ozeki, and K. Kobayashi, 70th International Symposium on Molecular Spectroscopy (2015), MH14.

  11. ANALYTICAL SOLUTIONS OF SINGULAR ISOTHERMAL QUADRUPOLE LENS

    SciTech Connect

    Chu Zhe; Lin, W. P.; Yang Xiaofeng E-mail: linwp@shao.ac.cn

    2013-06-20

    Using an analytical method, we study the singular isothermal quadrupole (SIQ) lens system, which is the simplest lens model that can produce four images. In this case, the radial mass distribution is in accord with the profile of the singular isothermal sphere lens, and the tangential distribution is given by adding a quadrupole on the monopole component. The basic properties of the SIQ lens have been studied in this Letter, including the deflection potential, deflection angle, magnification, critical curve, caustic, pseudo-caustic, and transition locus. Analytical solutions of the image positions and magnifications for the source on axes are derived. We find that naked cusps will appear when the relative intensity k of quadrupole to monopole is larger than 0.6. According to the magnification invariant theory of the SIQ lens, the sum of the signed magnifications of the four images should be equal to unity, as found by Dalal. However, if a source lies in the naked cusp, the summed magnification of the left three images is smaller than the invariant 1. With this simple lens system, we study the situations where a point source infinitely approaches a cusp or a fold. The sum of the magnifications of the cusp image triplet is usually not equal to 0, and it is usually positive for major cusps while negative for minor cusps. Similarly, the sum of magnifications of the fold image pair is usually not equal to 0 either. Nevertheless, the cusp and fold relations are still equal to 0 in that the sum values are divided by infinite absolute magnifications by definition.

  12. Multi-Pass Quadrupole Mass Analyzer

    NASA Technical Reports Server (NTRS)

    Prestage, John D.

    2013-01-01

    Analysis of the composition of planetary atmospheres is one of the most important and fundamental measurements in planetary robotic exploration. Quadrupole mass analyzers (QMAs) are the primary tool used to execute these investigations, but reductions in size of these instruments has sacrificed mass resolving power so that the best present-day QMA devices are still large, expensive, and do not deliver performance of laboratory instruments. An ultra-high-resolution QMA was developed to resolve N2 +/CO+ by trapping ions in a linear trap quadrupole filter. Because N2 and CO are resolved, gas chromatography columns used to separate species before analysis are eliminated, greatly simplifying gas analysis instrumentation. For highest performance, the ion trap mode is used. High-resolution (or narrow-band) mass selection is carried out in the central region, but near the DC electrodes at each end, RF/DC field settings are adjusted to allow broadband ion passage. This is to prevent ion loss during ion reflection at each end. Ions are created inside the trap so that low-energy particles are selected by low-voltage settings on the end electrodes. This is beneficial to good mass resolution since low-energy particles traverse many cycles of the RF filtering fields. Through Monte Carlo simulations, it is shown that ions are reflected at each end many tens of times, each time being sent back through the central section of the quadrupole where ultrahigh mass filtering is carried out. An analyzer was produced with electrical length orders of magnitude longer than its physical length. Since the selector fields are sized as in conventional devices, the loss of sensitivity inherent in miniaturizing quadrupole instruments is avoided. The no-loss, multi-pass QMA architecture will improve mass resolution of planetary QMA instruments while reducing demands on the RF electronics for high-voltage/high-frequency production since ion transit time is no longer limited to a single pass. The

  13. Precise calculations of the deuteron quadrupole moment

    SciTech Connect

    Gross, Franz L.

    2016-06-01

    Recently, two calculations of the deuteron quadrupole moment have have given predictions that agree with the measured value to within 1%, resolving a long-standing discrepancy. One of these uses the covariant spectator theory (CST) and the other chiral effective field theory (cEFT). In this talk I will first briefly review the foundations and history of the CST, and then compare these two calculations with emphasis on how the same physical processes are being described using very different language. The comparison of the two methods gives new insights into the dynamics of the low energy NN interaction.

  14. Nuclear quadrupole resonance echoes from hexamethylenetetramine.

    PubMed

    Ota, Go; Itozaki, Hideo

    2006-10-01

    We investigated the echo phenomenon of nuclear quadrupole resonance (NQR) from hexamethylenetetramine (HMT). We detected the pure NQR echo signal of HMT with a short pulse interval. The intensity of the echo signal increased as the pulse interval time was decreased. We observed that a clean echo signal was generated even when the pulse interval was shorter than the decay time constant T(2)(*). Since the short interval time gives a strong echo, our result insists that shorter interval time is preferred for the NQR detection.

  15. The Pipe-Quadrupole, an Alternative for High Gradient Interaction Region Quadrupole Designs

    SciTech Connect

    Oort, J.M. van; Scanlan, R.M.

    1996-12-12

    In the design of interaction region (IR) quadrupoles for high luminosity colliders such as the LHC or a possible upgrade of the Tevatron, the radiation heating of the coil windings is an important issue. Two obvious solutions to this problem can be chosen. The first is to reduce the heat load by added shielding, increased cooling with fins or using Nb{sub 3}Sn to increase the temperature margin. The second solution eliminates the conductor from the areas with the highest radiation intensity, which are located on the symmetry-axes of the midplanes of the coils. A novel quadrupole design is presented, in which the conductor is wound on four half-moon shaped supports, forming elongated toroid sections. The assembly of the four shapes yields a quadrupole field with an active flux return path, and a void in the high radiation area. This void can be occupied by a liquid helium cooling pipe to lower the temperature of the windings from the inside. The coil layout, harmonic optimization and mechanical design are shown, together with the calculated temperature rise for the radiation load of the LHC interaction region quadrupoles.

  16. SSC Quadrupole Magnet Performance at LBL

    SciTech Connect

    Lietzke, A.F.; Barale, P.; Benjegerdes, r.; Caspi, S.; Cortella, J.; Dell'Orco, D.; Gilbert, W.; Green, M.I.; Mirk, K.; Peters, C.; Scalan, R.; Taylor, C.E.; Wandesforde, A.

    1992-10-01

    Lawrence Berkeley Laboratory (LBL) contracted to design, construct, and test four short (1m) models and six full-size (5m) models of the Superconducting Super Collider (SSC) main-ring 5 meter focusing quadrupole magnet (211 Tesla/meter). The training performance of these magnets is summarized. Magnets were tested in a horizontal boiling helium (1 Atm) cryostat. The magnetic, strain-gage and training responses to two thermal cycles were measured. The quadrupole gradient, and relative multipole purity were determined from Fourier analysis of the rotating coil signals. Magnetic and strain-gage measurements were taken on-the-fly. The voltage-tap data was analyzed to determine quench-origin and propagation characteristics. Quench-training proceeded at 4.3K until a plateau was achieved or sub-cooling (2.5K) was used to accelerate the training process. The early short (1m) magnets were also trained at 1.8K (10kA) to help identify potential weak areas. The MIITs were calculated to compare various magnet protection methods. Except for modest training above the anticipated SSC operating point, the magnets performed very well and proved to be self-protecting. Some design flaws were identified and corrected. The last two 1 m models and all the 5m models have been reinstalled in cryostats at the SSC Laboratory, retested and used to achieve various milestones in their program.

  17. Explosives detection with quadrupole resonance analysis

    NASA Astrophysics Data System (ADS)

    Rayner, Timothy J.; Thorson, Benjamin D.; Beevor, Simon; West, Rebecca; Krauss, Ronald A.

    1997-02-01

    The increase in international terrorist activity over the past decade has necessitated the exploration of new technologies for the detection of plastic explosives. Quadrupole resonance analysis (QRA) has proven effective as a technique for detecting the presence of plastic, sheet, and military explosive compounds in small quantities, and can also be used to identify narcotics such as heroin and cocaine base. QRA is similar to the widely used magnetic resonance (MR) and magnetic resonance imaging (MRI) techniques, but has the considerable advantage that the item being inspected does not need to be immersed in a steady, homogeneous magnetic field. The target compounds are conclusively identified by their unique quadrupole resonance frequencies. Quantum magnetics has develop and introduced a product line of explosives and narcotics detection devices based upon QRA technology. The work presented here concerns a multi-compound QRA detection system designed to screen checked baggage, cargo, and sacks of mail at airports and other high-security facilities. The design philosophy and performance are discussed and supported by test results from field trials conducted in the United States and the United Kingdom. This detection system represents the current state of QRA technology for field use in both commercial and government sectors.

  18. Quadrupole Collectivity in Neutron Deficient Sn Isotopes

    NASA Astrophysics Data System (ADS)

    Gade, Alexandra

    2014-03-01

    One of the overarching goals of nuclear physics is the development of a comprehensive model of the atomic nucleus with predictive power across the nuclear chart. Of particular importance for the development of nuclear models is experimental data that consistently track the effect of isospin and changed binding, for example. The chain of Sn isotopes has been a formidable testing ground for nuclear models as some spectroscopic data is available from N = Z = 50 100Sn in the proximity of the proton dripline to 134Sn, beyond the very neutron-rich doubly magic nucleus 132Sn. In even-even nuclei, the electromagnetic quadrupole excitation strength is a measure of quadrupole collectivity, sensitive to the presence of shell gaps, nuclear deformation, and nucleon-nucleon correlations, for example. In the Sn isotopes, this transition strength has been reported from 104Sn to 130Sn, spanning a chain of 14 even-even Sn isotopes. The trend is asymmetric with respect to midshell and not even the largest-scale shell-model calculations have been able to describe the evolution of transition strength across the isotopic chain without varying effective charges. Implications will be discussed. This work was supported by the National Science Foundation under Grant No. PHY-1102511.

  19. Magnetic quench antenna for MQXF quadrupoles

    DOE PAGES

    Marchevsky, Maxim; Sabbi, GianLuca; Prestemon, Soren; ...

    2016-12-21

    High-field MQXF-series quadrupoles are presently under development by LARP and CERN for the upcoming LHC luminosity upgrade. Quench training and protection studies on MQXF prototypes require a capability to accurately localize quenches and measure their propagation velocity in the magnet coils. The voltage tap technique commonly used for such purposes is not a convenient option for the 4.2-m-long MQXF-A prototype, nor can it be implemented in the production model. We have developed and tested a modular inductive magnetic antenna for quench localization. The base element of our quench antenna is a round-shaped printed circuit board containing two orthogonal pairs ofmore » flat coils integrated with low-noise preamplifiers. The elements are aligned axially and spaced equidistantly in 8-element sections using a supporting rod structure. The sections are installed in the warm bore of the magnet, and can be stacked together to adapt for the magnet length. We discuss the design, operational characteristics and preliminary qualification of the antenna. Lastly, axial quench localization capability with an accuracy of better than 2 cm has been validated during training test campaign of the MQXF-S1 quadrupole.« less

  20. Magnetic quench antenna for MQXF quadrupoles

    SciTech Connect

    Marchevsky, Maxim; Sabbi, GianLuca; Prestemon, Soren; Strauss, Thomas; Stoynev, Stoyan; Chlachidze, Guram

    2016-12-21

    High-field MQXF-series quadrupoles are presently under development by LARP and CERN for the upcoming LHC luminosity upgrade. Quench training and protection studies on MQXF prototypes require a capability to accurately localize quenches and measure their propagation velocity in the magnet coils. The voltage tap technique commonly used for such purposes is not a convenient option for the 4.2-m-long MQXF-A prototype, nor can it be implemented in the production model. We have developed and tested a modular inductive magnetic antenna for quench localization. The base element of our quench antenna is a round-shaped printed circuit board containing two orthogonal pairs of flat coils integrated with low-noise preamplifiers. The elements are aligned axially and spaced equidistantly in 8-element sections using a supporting rod structure. The sections are installed in the warm bore of the magnet, and can be stacked together to adapt for the magnet length. We discuss the design, operational characteristics and preliminary qualification of the antenna. Lastly, axial quench localization capability with an accuracy of better than 2 cm has been validated during training test campaign of the MQXF-S1 quadrupole.

  1. Electrostatic quadrupole focused particle accelerating assembly with laminar flow beam

    DOEpatents

    Maschke, A.W.

    1984-04-16

    A charged particle accelerating assembly provided with a predetermined ratio of parametric structural characteristics and with related operating voltages applied to each of its linearly spaced focusing and accelerating quadrupoles, thereby to maintain a particle beam traversing the electrostatic fields of the quadrupoles in the assembly in an essentially laminar flow through the assembly.

  2. Differentially pumped dual linear quadrupole ion trap mass spectrometer

    DOEpatents

    Owen, Benjamin C.; Kenttamaa, Hilkka I.

    2016-11-15

    The present disclosure provides a new tandem mass spectrometer and methods of using the same for analyzing charged particles. The differentially pumped dual linear quadrupole ion trap mass spectrometer of the present disclose includes a combination of two linear quadrupole (LQIT) mass spectrometers with differentially pumped vacuum chambers.

  3. Differentially pumped dual linear quadrupole ion trap mass spectrometer

    DOEpatents

    Owen, Benjamin C.; Kenttamaa, Hilkka I.

    2015-10-20

    The present disclosure provides a new tandem mass spectrometer and methods of using the same for analyzing charged particles. The differentially pumped dual linear quadrupole ion trap mass spectrometer of the present disclose includes a combination of two linear quadrupole (LQIT) mass spectrometers with differentially pumped vacuum chambers.

  4. Monopole, Quadrupole and Pairing: a Shell Model View

    NASA Astrophysics Data System (ADS)

    Zuker, A. P.

    The three main contributions to the nuclear Hamiltonian-monopole, quadrupole and pairing - are analyzed in a shell model context. The first has to be treated phenomenologically, while the other two can be reliably extracted from the realistic interactions. Due to simple scaling properties, the realistic quadrupole and pairing interactions eliminate the tendency to collapse of their conventional counterparts, while retaining their basic simplicity.

  5. Electrostatic quadrupole focused particle accelerating assembly with laminar flow beam

    DOEpatents

    Maschke, Alfred W.

    1985-01-01

    A charged particle accelerating assembly provided with a predetermined ratio of parametric structural characteristics and with related operating voltages applied to each of its linearly spaced focusing and accelerating quadrupoles, thereby to maintain a particle beam traversing the electrostatic fields of the quadrupoles in the assembly in an essentially laminar flow throughout the assembly.

  6. Vibrational spectroscopy

    Treesearch

    Umesh P. Agarwal; Rajai Atalla

    2010-01-01

    Vibrational spectroscopy is an important tool in modern chemistry. In the past two decades, thanks to significant improvements in instrumentation and the development of new interpretive tools, it has become increasingly important for studies of lignin. This chapter presents the three important instrumental methods-Raman spectroscopy, infrared (IR) spectroscopy, and...

  7. Synchrotron Tune Adjustment by Longitudinal Motion of Quadrupoles

    NASA Astrophysics Data System (ADS)

    Bertsche, K. J.

    1996-05-01

    Adjustment of the tune of a synchrotron is generally accomplished by globally varying the strength of quadrupoles, either in the main quadrupole bus or in a set of dedicated trim quadrupoles distributed around the ring. An alternate scheme for tune control involves varying the strengths of quadrupoles only within a local insert, thereby adjusting the phase advance across this insert to create a "phase trombone." In a synchrotron built of permanent magnets, such as the proposed Fermilab Recycler Ring, tune adjustment may also be accomplished by constructing a phase trombone in which the longitudinal position rather than strength of a number of quadrupoles is adjusted. Design philosophies and performance for such phase trombones will be presented. *Operated by Universities Research Association, Inc., under contract with the US. Department of Energy.

  8. Double-photoionization of helium including quadrupole radiation effects

    SciTech Connect

    Colgan, James; Ludlow, J A; Lee, Teck - Ghee; Pindzola, M S; Robicheaux, F

    2009-01-01

    Non-perturbative time-dependent close-coupling calculations are carried out for the double photoionization of helium including both dipole and quadrupole radiation effects. At a photon energy of 800 eV, accessible at CUlTent synchrotron light sources, the quadrupole interaction contributes around 6% to the total integral double photoionization cross section. The pure quadrupole single energy differential cross section shows a local maxima at equal energy sharing, as opposed to the minimum found in the pure dipole single energy differential cross section. The sum of the pure dipole and pure quadrupole single energy differentials is insensitive to non-dipole effects at 800 eV. However, the triple differential cross section at equal energy sharing of the two ejected electrons shows strong non-dipole effects due to the quadrupole interaction that may be experimentally observable.

  9. VIBRATIONALLY EXCITED C{sub 6}H

    SciTech Connect

    Gottlieb, C. A.; McCarthy, M. C.; Thaddeus, P.

    2010-08-15

    Rotational spectra of the linear carbon chain radical C{sub 6}H in two low-lying excited vibrational states were observed both at millimeter wavelengths in a low-pressure glow discharge and at centimeter wavelengths in a supersonic molecular beam. Two series of harmonically related lines with rotational constants within 0.3% of the {sup 2{Pi}} ground state were assigned to the {sup 2{Sigma}} and {sup 2{Delta}} vibronic components of an excited bending vibrational level. Measurements of the intensities of the lines in the glow discharge indicate that the {sup 2{Sigma}} component lies very close to ground, but the {sup 2{Delta}} component is much higher in energy. The standard Hamiltonian for an isolated {sup 2{Delta}} state with five spectroscopic constants reproduces the observed rotational spectrum, but several high-order distortion terms in the spin-rotation interaction are needed to reproduce the spectrum of the {sup 2{Sigma}} component in C{sub 6}H and C{sub 6}D. The derived spectroscopic constants allow astronomers to calculate the rotational spectra of the {sup 2{Sigma}} and {sup 2{Delta}} states up to 260 GHz to within 0.1 km s{sup -1} or better in equivalent radial velocity.

  10. Modeled changes in extreme wave climates in the Pacific Ocean during the 21st century and implications for low-lying U.S. and U.S.-affiliated atoll islands

    NASA Astrophysics Data System (ADS)

    Shope, J. B.; Storlazzi, C. D.; Erikson, L. H.; Hegermiller, C.

    2014-12-01

    . As most atoll islets accrete during large wave events, decreasing wave heights during other seasons may inhibit atoll islet accretion such that the low-lying islets may not be able to keep up with projected sea-level rise.

  11. C1s and O1s photoelectron satellite spectra of CO with symmetry-dependent vibrational excitations

    NASA Astrophysics Data System (ADS)

    Ehara, M.; Kuramoto, K.; Nakatsuji, H.; Hoshino, M.; Tanaka, T.; Kitajima, M.; Tanaka, H.; De Fanis, A.; Tamenori, Y.; Ueda, K.

    2006-09-01

    The photoelectron shake-up satellite spectra that accompany the C1s and O1s main lines of carbon monoxide have been studied by a combination of high-resolution x-ray photoelectron spectroscopy and accurate ab initio calculations. The symmetry-adapted cluster-expansion configuration-interaction general-R method satisfactorily reproduces the satellite spectra over a wide energy region, and the quantitative assignments are proposed for the 16 and 12 satellite bands for C1s and O1s spectra, respectively. Satellite peaks above the π-1π * transitions are mainly assigned to the Rydberg excitations accompanying the inner-shell ionization. Many shake-up states, which interact strongly with three-electron processes such as π-2π*2 and n-2π*2, are calculated in the low-energy region, while the continuous Rydberg excitations are obtained with small intensities in the higher-energy region. The vibrational structures of low-lying shake-up states have been examined for both C1s and O1s ionizations. The vibrational structures appear in the low-lying C1s satellite states, and the symmetry-dependent angular distributions for the satellite emission have enabled the Σ and Π symmetries to be resolved. On the other hand, the potential curves of the low-lying O1s shake-up states are predicted to be weakly bound or repulsive.

  12. Electrodynamical forbiddance of strong quadrupole light-molecule interaction in the methane molecule and its manifestation in surface enhanced hyper Raman scattering spectra

    NASA Astrophysics Data System (ADS)

    Polubotko, A. M.

    2015-01-01

    It is demonstrated in the framework of the dipole-quadrupole theory that strong quadrupole light-molecule interaction, which is responsible for the most enhancement in SEHRS experiences a so- called electrodynamical forbiddance in the methane molecule, which belongs to the T d symmetry group, due to the electrodynamical law div E = 0 and does not infuence on the formation of the SEHRS spectra. This forbiddance results in the fact that the lines caused by totally symmetric vibrations transforming after the unit irreducible representation, which are observed in symmetrical molecules with another groups of sufficiently high symmetry, such as pyrazine and phenazine, must be small or absent at all. In this case, in methane, the most enhanced lines are those caused by the vibrations transforming after the irreducible representation F 2.

  13. Rescuing the nonjet (NJ) azimuth quadrupole from the flow narrative

    NASA Astrophysics Data System (ADS)

    Trainor, Thomas A.

    2017-04-01

    According to the flow narrative commonly applied to high-energy nuclear collisions a cylindrical-quadrupole component of 1D azimuth angular correlations is conventionally denoted by quantity υ2 and interpreted to represent elliptic flow. Jet angular correlations may also contribute to υ2 data "nonflow" depending on the method used to calculate υ2, but 2D graphical methods are available to insure accurate separation. The nonjet (NJ) quadrupole has various properties inconsistent with a flow interpretation, including the observation that NJ quadrupole centrality variation in A-A collisions has no relation to strongly-varying jet modication ("jet quenching") in those collisions commonly attributed to jet interaction with a flowing dense medium. In this presentation I describe isolation of quadrupole spectra from pt-differential υ2(pt) data from the RHIC and LHC. I demonstrate that quadrupole spectra have characteristics very different from the single-particle spectra for most hadrons, that quadrupole spectra indicate a common boosted hadron source for a small minority of hadrons that "carry" the NJ quadrupole structure, that the narrow source-boost distribution is characteristic of an expanding thin cylindrical shell (strongly contradicting hydro descriptions), and that in the boost frame a single universal quadrupole spectrum (Lévy distribution) on transverse mass mt accurately describes data for several hadron species scaled according to their statistical-model abundances. The quadrupole spectrum shape changes very little from RHIC to LHC energies. Taken in combination those characteristics strongly suggest a unique nonflow (and nonjet) QCD mechanism for the NJ quadrupole conventionally represented by υ2.

  14. Supersonic Quadrupole Noise Theory for High-Speed Helicopter Rotors

    NASA Technical Reports Server (NTRS)

    Farassat, F.; Brentner, Kenneth S.

    1997-01-01

    High-speed helicopter rotor impulsive noise prediction is an important problem of aeroacoustics. The deterministic quadrupoles have been shown to contribute significantly to high-speed impulsive (HSI) noise of rotors, particularly when the phenomenon of delocalization occurs. At high rotor-tip speeds, some of the quadrupole sources lie outside the sonic circle and move at supersonic speed. Brentner has given a formulation suitable for efficient prediction of quadrupole noise inside the sonic circle. In this paper, we give a simple formulation based on the acoustic analogy that is valid for both subsonic and supersonic quadrupole noise prediction. Like the formulation of Brentner, the model is exact for an observer in the far field and in the rotor plane and is approximate elsewhere. We give the full analytic derivation of this formulation in the paper. We present the method of implementation on a computer for supersonic quadrupoles using marching cubes for constructing the influence surface (Sigma surface) of an observer space- time variable (x; t). We then present several examples of noise prediction for both subsonic and supersonic quadrupoles. It is shown that in the case of transonic flow over rotor blades, the inclusion of the supersonic quadrupoles improves the prediction of the acoustic pressure signature. We show the equivalence of the new formulation to that of Brentner for subsonic quadrupoles. It is shown that the regions of high quadrupole source strength are primarily produced by the shock surface and the flow over the leading edge of the rotor. The primary role of the supersonic quadrupoles is to increase the width of a strong acoustic signal.

  15. Manifestation of a strong quadrupole interaction and peculiarities in the SERS and SEHRS spectra of 4,4'-bipyridine

    NASA Astrophysics Data System (ADS)

    Golovin, A. V.; Polubotko, A. M.

    2017-07-01

    The paper analyzes Surface Enhanced Raman Scattering (SERS) and Surface Enhanced Hyper Raman Scattering (SEHRS) spectra of 4,4'-bypiridine molecule for two possible geometries, which are described by D 2 and D 2 h symmetry groups. It is pointed out on appearance of sufficiently strong lines, caused by vibrations with the unit irreducible representation for both possible configurations. Appearance of these lines in the SEHRS spectrum points out the existence of a strong quadrupole light-molecule interaction. In addition one observes the lines, caused by vibrations both with the unit irreducible representations A or A g and the irreducible representation B 1 or B 1 u . The last ones describe transformational properties of the d z component of the dipole moment, which is perpendicular to the surface. This property of the spectrum is caused by peculiarity of the geometry of the molecule, which consists of two benzene rings, which are weakly connected with each other. The linear combinations of the vibrations of the rings create two nearly degenerated symmetric and anti symmetrical states, which cannot be identified in the experimental spectra. The result is in a full agreement with the dipole-quadrupole theory of SERS and SEHRS.

  16. Gas phase vibrational spectroscopy of cold (TiO 2 ) n - (n = 3-8) clusters

    NASA Astrophysics Data System (ADS)

    Weichman, Marissa L.; Song, Xiaowei; Fagiani, Matias R.; Debnath, Sreekanta; Gewinner, Sandy; Schöllkopf, Wieland; Neumark, Daniel M.; Asmis, Knut R.

    2016-03-01

    We report infrared photodissociation (IRPD) spectra for the D2-tagged titanium oxide cluster anions (TiO 2 ) n - with n = 3-8 in the spectral region from 450 to 1200 cm-1. The IRPD spectra are interpreted with the aid of harmonic spectra from BP86/6-311+G* density functional theory calculations of energetically low-lying isomers. We conclusively assign the IRPD spectra of the n = 3 and n = 6 clusters to global minimum energy structures with Cs and C2 symmetry, respectively. The vibrational spectra of the n = 4 and n = 7 clusters can be attributed to contributions of at most two low-lying structures. While our calculations indicate that the n = 5 and n = 8 clusters have many more low-lying isomers than the other clusters, the dominant contributions to their spectra can be assigned to the lowest energy structures. Through comparison between the calculated and experimental spectra, we can draw conclusions about the size-dependent evolution of the properties of (TiO 2 ) n - clusters, and on their potential utility as model systems for catalysis on a bulk TiO2 surface.

  17. Gas phase vibrational spectroscopy of cold (TiO2)n(-) (n = 3-8) clusters.

    PubMed

    Weichman, Marissa L; Song, Xiaowei; Fagiani, Matias R; Debnath, Sreekanta; Gewinner, Sandy; Schöllkopf, Wieland; Neumark, Daniel M; Asmis, Knut R

    2016-03-28

    We report infrared photodissociation (IRPD) spectra for the D2-tagged titanium oxide cluster anions (TiO2)n(-) with n = 3-8 in the spectral region from 450 to 1200 cm(-1). The IRPD spectra are interpreted with the aid of harmonic spectra from BP86/6-311+G* density functional theory calculations of energetically low-lying isomers. We conclusively assign the IRPD spectra of the n = 3 and n = 6 clusters to global minimum energy structures with Cs and C2 symmetry, respectively. The vibrational spectra of the n = 4 and n = 7 clusters can be attributed to contributions of at most two low-lying structures. While our calculations indicate that the n = 5 and n = 8 clusters have many more low-lying isomers than the other clusters, the dominant contributions to their spectra can be assigned to the lowest energy structures. Through comparison between the calculated and experimental spectra, we can draw conclusions about the size-dependent evolution of the properties of (TiO2)n(-) clusters, and on their potential utility as model systems for catalysis on a bulk TiO2 surface.

  18. RADIATION RESISTANT HTS QUADRUPOLES FOR RIA.

    SciTech Connect

    GUPTA,R.; ANERELLA,M.; HARRISON,M.; ET AL.

    2004-10-03

    Extremely high radiation, levels with accumulated doses comparable to those in nuclear reactors than in accelerators, and very high heat loads ({approx}15 kw) make the quadrupole magnets in the fragment separator one of the most challenging elements of the proposed Rare Isotope Accelerator (RIA). Removing large heat loads, protecting the superconducting coils against quenching, the long term survivability of magnet components, and in particular, insulation that can retain its functionality in such a harsh environment, are the major challenges associated with such magnets. A magnet design based on commercially available high temperature superconductor (HTS) and stainless steel tape insulation has been developed. HTS will efficiently remove these large heat loads and stainless steel can tolerate these large radiation doses. Construction of a model magnet has been started with several coils already built and tested. This paper presents the basic magnet design, results of the coil tests, the status and the future plans. In addition, preliminary results of radiation calculations are also presented.

  19. Quadrupole magnet for a rapid cycling synchrotron

    SciTech Connect

    Witte, H.; Berg, J. S.

    2015-05-03

    Rapid Cycling Synchrotrons (RCS) feature interleaved warm and cold dipole magnets; the field of the warm magnets is used to modulate the average bending field depending on the particle energy. It has been shown that RCS can be an attractive option for fast acceleration of particles, for example, muons, which decay quickly. In previous studies it was demonstrated that in principle warm dipole magnets can be designed which can provide the required ramp rates, which are equivalent to frequencies of about 1 kHz. To reduce the losses it is beneficial to employ two separate materials for the yoke; it was also shown that by employing an optimized excitation coil geometry the eddy current losses are acceptable. In this paper we show that the same principles can be applied to quadrupole magnets targeting 30 T/m with a repetition rate of 1kHz and good field quality.

  20. Quadrupole resonance scanner for narcotics detection

    NASA Astrophysics Data System (ADS)

    Shaw, Julian D.; Moeller, C. R.; Magnuson, Erik E.; Sheldon, Alan G.

    1994-10-01

    Interest in non-invasive, non-hazardous, bulk detection technologies for narcotics interdiction has risen over the last few years. As part of our continuing research and development programs in detection of narcotics and explosives using sensitive magnetic measuring devices, we present the first commercially available prototype Quadrupole Resonance (QR) scanner for narcotics detection. The portable narcotics detection system was designed in modular form such that a single QR base system could be easily used with a variety of custom detection heads. The QR system presented in this paper is suitable for scanning items up to 61 X 35 X 13 cm in size, and was designed to scan mail packages and briefcase-sized items for the presence of narcotics. System tests have shown that detection sensitivity is comparable that obtained in laboratory systems.

  1. Explosives detection by nuclear quadrupole resonance (NQR)

    NASA Astrophysics Data System (ADS)

    Garroway, Allen N.; Buess, Michael L.; Yesinowski, James P.; Miller, Joel B.; Krauss, Ronald A.

    1994-10-01

    Pure nuclear quadrupole resonance (NQR) of 14N nuclei is quite promising as a method for detecting explosives such as RDX and contraband narcotics such as cocaine and heroin in quantities of interest. Pure NQR is conducted without an external applied magnetic field, so potential concerns about damage to magnetically encoded data or exposure of personnel to large magnetic fields are not relevant. Because NQR frequencies of different compounds are quite distinct, we do not encounter false alarms from the NQR signals of other benign materials. We have constructed a laboratory prototype NQR explosives detector which interrogates a volume of 300 liters (10 ft3). This paper presents abbreviated results from a demonstration of the laboratory prototype NQR explosives detector conducted at the Federal Aviation Administration Technical Center in May 1994 on RDX-based explosives.

  2. An improved integrally formed radio frequency quadrupole

    DOEpatents

    Abbott, S.R.

    1987-10-05

    An improved radio frequency quadrupole is provided having an elongate housing with an elongate central axis and top, bottom and two side walls symmetrically disposed about the axis, and vanes formed integrally with the walls, the vanes each having a cross-section at right angles to the central axis which tapers inwardly toward the axis to form electrode tips spaced from each other by predetermined distances. Each of the four walls, and the vanes integral therewith, is a separate structural element having a central lengthwise plane passing through the tip of the vane, the walls having flat mounting surfaces at right angles to and parallel to the control plane, respectively, which are butted together to position the walls and vane tips relative to each other. 4 figs.

  3. Atomic Quadrupole Moment Measurement Using Dynamic Decoupling.

    PubMed

    Shaniv, R; Akerman, N; Ozeri, R

    2016-04-08

    We present a method that uses dynamic decoupling of a multilevel quantum probe to distinguish small frequency shifts that depend on m_{j}^{2}, where m_{j}^{2} is the angular momentum of level |j⟩ along the quantization axis, from large noisy shifts that are linear in m_{j}, such as those due to magnetic field noise. Using this method we measured the electric-quadrupole moment of the 4D_{5/2} level in ^{88}Sr^{+} to be 2.973_{-0.033}^{+0.026}ea_{0}^{2}. Our measurement improves the uncertainty of this value by an order of magnitude and thus helps mitigate an important systematic uncertainty in ^{88}Sr^{+} based optical atomic clocks and verifies complicated many-body quantum calculations.

  4. Hybrid high gradient permanent magnet quadrupole

    NASA Astrophysics Data System (ADS)

    N'gotta, P.; Le Bec, G.; Chavanne, J.

    2016-12-01

    This paper presents an innovative compact permanent magnet quadrupole with a strong gradient for potential use in future light source lattices. Its magnetic structure includes simple mechanical parts, rectangular permanent magnet blocks and soft iron poles. It has a wide aperture in the horizontal plane to accommodate an x-ray beam port, a common constraint in storage ring-based light sources. This specificity introduces field quality deterioration because of the resulting truncation of the poles; a suitable field quality can be restored with an optimized pole shape. A 82 T /m prototype with a bore radius of 12 mm and a 10 mm vertical gap between poles has been constructed and magnetically characterized. Gradient inhomogeneities better than 10-3 in the good field region were obtained after the installation of special shims.

  5. Intermediate energy electron impact excitation of composite vibrational modes in phenol.

    PubMed

    Neves, R F C; Jones, D B; Lopes, M C A; Nixon, K L; de Oliveira, E M; da Costa, R F; Varella, M T do N; Bettega, M H F; Lima, M A P; da Silva, G B; Brunger, M J

    2015-05-21

    We report differential cross section results from an experimental investigation into the electron impact excitation of a number of the low-lying composite (unresolved) vibrational modes in phenol (C6H5OH). The measurements were carried out at incident electron energies in the range 15-40 eV and for scattered-electron angles in the range 10-90°. The energy resolution of those measurements was typically ∼80 meV. Calculations, using the GAMESS code, were also undertaken with a B3LYP/aug-cc-pVDZ level model chemistry, in order to enable us to assign vibrational modes to the features observed in our energy loss spectra. To the best of our knowledge, the present cross sections are the first to be reported for vibrational excitation of the C6H5OH molecule by electron impact.

  6. Parameterized Bases for Calculating Vibrational Spectra Directly from ab Initio Data Using Rectangular Collocation.

    PubMed

    Chan, Matthew; Manzhos, Sergei; Carrington, Tucker; Yamashita, Koichi

    2012-06-12

    We compared different parametrized bases for computing anharmonic vibrational spectra using a new version of the rectangular collocation-optimization method of Manzhos and Carrington (Can. J. Chem. 2009, 87, 864; Chem. Phys. Lett. 2011, 511, 434). The method enables one to compute a small number of vibrational levels with an ultrasmall basis set without a potential function. To test the ideas, parametrized uncoupled and coupled Gaussian functions as well as direct-product and coupled Hermite basis sets are used to compute four low-lying vibrational energy levels of H2O on model harmonic and anharmonic uncoupled (polynomial) potential energy surfaces. In addition, we compute levels directly from ab initio points and thereby include all coupling and anharmonicity. We conclude that uncoupled parametrized Gaussian and Hermite functions are a good choice for anharmonic and coupled problems.

  7. High-resolution vibrational and rotational spectroscopy of CD2H+ in a cryogenic ion trap

    NASA Astrophysics Data System (ADS)

    Jusko, Pavol; Stoffels, Alexander; Thorwirth, Sven; Brünken, Sandra; Schlemmer, Stephan; Asvany, Oskar

    2017-02-01

    The low-lying rotational states (J = 0, … , 5) of CD2H+ have been probed by high-resolution ro-vibrational and pure rotational spectroscopy, applying several action spectroscopic methods in a cryogenic 22-pole ion trap. For this, the ν1 ro-vibrational band has been revisited, detecting 108 transitions, among which 36 are new. The use of a frequency comb system allowed us to measure the ro-vibrational transitions with high precision and accuracy, typically better than 1 MHz. The high precision has been confirmed by comparing equal combination differences in the ground and excited state. Moreover, precise predictions of pure rotational transitions were possible for the ground state. Twenty-five rotational transitions have been detected directly by a novel IR-mm-wave double resonance method, giving rise to highly accurate ground state spectroscopic parameters.

  8. Intermediate energy electron impact excitation of composite vibrational modes in phenol

    SciTech Connect

    Neves, R. F. C.; Jones, D. B.; Lopes, M. C. A.; Nixon, K. L.; Oliveira, E. M. de; Lima, M. A. P.; Costa, R. F. da; Varella, M. T. do N.; Bettega, M. H. F.; Silva, G. B. da; Brunger, M. J.

    2015-05-21

    We report differential cross section results from an experimental investigation into the electron impact excitation of a number of the low-lying composite (unresolved) vibrational modes in phenol (C{sub 6}H{sub 5}OH). The measurements were carried out at incident electron energies in the range 15–40 eV and for scattered-electron angles in the range 10–90°. The energy resolution of those measurements was typically ∼80 meV. Calculations, using the GAMESS code, were also undertaken with a B3LYP/aug-cc-pVDZ level model chemistry, in order to enable us to assign vibrational modes to the features observed in our energy loss spectra. To the best of our knowledge, the present cross sections are the first to be reported for vibrational excitation of the C{sub 6}H{sub 5}OH molecule by electron impact.

  9. Good Vibrations

    NASA Technical Reports Server (NTRS)

    2001-01-01

    A Small Business Innovation Research (SBIR) sponsorship from NASA's Dryden Flight Research Center, assisted MetroLaser, of Irvine, California, in the development of a self-aligned laser vibrometer system. VibroMet, capable of measuring surface vibrations in a variety of industries, provides information on the structural integrity and acoustical characteristics of manufactured products. This low-cost, easy-to-use sensor performs vibration measurement from distances of up to three meters without the need for adjustment. The laser beam is simply pointed at the target and the system then uses a compact laser diode to illuminate the surface and to subsequently analyze the reflected light. The motion of the surface results in a Doppler shift that is measured with very high precision. VibroMet is considered one of the many behind-the-scenes tools that can be relied on to assure the quality, reliability and safety of everything from airplane panels to disk brakes

  10. Vibration syndrome

    PubMed Central

    Stewart, Alice M.; Goda, D. F

    1970-01-01

    Stewart, Alice M., and Goda, D. F. (1970).Brit. J. industr. Med.,27, 19-27. Vibration syndrome. Raynaud's phenomenon, or the finger blanching of men who work with vibrating tools, is undoubtedly due to vasospasm. Nevertheless the abnormal element in the situation is not a series of traumatized nerve endings but a deposition of callus under the palmar surfaces of fingers and thumbs. This deposition is a late consequence of the most distinctive, but not necessarily the most painful, of the numerous effects incurred as a result of the tool speed being completely out of the control of the operator and of the tool/component rebound being only partially under his control. The replacement of soft finger pads by rigid callus is also the only consequence of hard manual work to show how necessary it is for a structure like a finger–which is largely composed of bones, joints, tendons, and skin–to have a reservoir, the equivalent of a blood-filled sponge, between every joint to accommodate any sudden reduction in blood volume, or indeed any sudden increase in the volume of blood held in the arteries and veins relative to the amount held in the capillaries. It is still a moot point whether users of vibrating tools have more arm complaints of a serious nature than other manual workers. They do, however, have a multiplicity of aches and pains, ascribable to various causes including tool speed and tool/component rebound, which are in toto very sensitive to such things as blunt impacts, hard components, heavy tools, awkward jobs, and inept handling of tools, whether the ineptness be due to inexperience or to advancing age. Users of vibrating tools have more pain in the hands and wrists than in the elbows and shoulders, but the pain tends to persist longer in the latter sites than in the former sites. PMID:5418915

  11. Vibrational excitation in low-energy electron scattering by H 2 molecules physisorbed on a metal surface

    NASA Astrophysics Data System (ADS)

    Teillet-Billy, D.; Stibbe, D. T.; Tennyson, J.; Gauyacq, J. P.

    1999-12-01

    The electron impact vibrational excitation of H 2 molecules physisorbed on a free-electron metal surface is studied theoretically at collision energies of a few eV. The role of the short-lived low-lying 2Σ u resonance is investigated. The electron scattering by a free H 2 molecule is described by the R-matrix method and the corresponding results are used to model the electron scattering by the physisorbed molecule with the coupled angular mode (CAM) method. The strength of the vibrational excitation and, in particular, the overtone vibrational excitation ratio are found to be smaller for the physisorbed molecule than for the free molecule. However, the energy dependence of the vibrational excitation process is found to be weakly influenced by the physisorption, as observed experimentally by Demuth et al. [Phys. Rev. Lett. 47 (1981) 1166].

  12. Particle-vibration coupling: Recent advances in microscopic calculations with the Skyrme Hamiltonian

    SciTech Connect

    Colò, G.; Baldo, M.; Bortignon, P. F.; Rizzo, D.; Bocchi, G.

    2016-11-15

    In this contribution, we report some recent progress in our understanding of particle-vibration coupling (PVC) in nuclei. In particular, we first review the formal development that has allowed some of us to deduce the PVC equations within the Green’s functionmethod. Applications are then discussed, both in the case of single-particle states and giant resonances in magic nuclei. We also present a new model that extends the PVC ansatz and is meant to account for the complete low-lying spectra of odd nuclei.

  13. Particle-vibration coupling: Recent advances in microscopic calculations with the Skyrme Hamiltonian

    NASA Astrophysics Data System (ADS)

    Colò, G.; Baldo, M.; Bortignon, P. F.; Rizzo, D.; Bocchi, G.

    2016-11-01

    In this contribution, we report some recent progress in our understanding of particle-vibration coupling (PVC) in nuclei. In particular, we first review the formal development that has allowed some of us to deduce the PVC equations within the Green's functionmethod. Applications are then discussed, both in the case of single-particle states and giant resonances in magic nuclei. We also present a new model that extends the PVC ansatz and is meant to account for the complete low-lying spectra of odd nuclei.

  14. Vibrationally resolved cross sections for the photoionization of CS2

    NASA Astrophysics Data System (ADS)

    Stratmann, R. E.; Lucchese, Robert R.

    1994-12-01

    We have performed vibrationally resolved calculations of the excitation of the symmetric stretch in the photoionization of CS2 leading to the X 2Πg, A 2Πu, B 2Σ+u, and C 2Σ+g states of CS+2. Previous theoretical work has determined that the kπg shape resonance in the (5σu)-1 channel consists mainly of a linear combination of low lying virtual d orbitals on sulfur and is thus essentially atomic in nature. This conclusion was primarily based on the shape of the resonant wave function and the insensitivity of the energy of the resonance to bond stretching. Here, we have determined that the energies of the kπ shape resonances located well above threshold and the σ bound states just below threshold are insensitive to bond length. We have also found nearly constant vibrational branching ratios in all channels and polarization components. This is in qualitative agreement with experimental vibrationally resolved cross sections [S. Kakar, H. C. Choi, and E. D. Poliakoff, J. Chem. Phys. 97, 4690 (1992)] which show nearly constant vibrational branching ratios. Our present results indicate that caution must be exercised when using bond length sensitivity as an exclusive means to determine the existence of shape resonances.

  15. Development of Superconducting Focusing Quadrupoles for Heavy Ion Drivers

    SciTech Connect

    Martovetsky, N; Manahan, R; Lietzke, A F

    2001-09-10

    Heavy Ion Fusion (HIF) is exploring a promising path to a practical inertial-confinement fusion reactor. The associated heavy ion driver will require a large number of focusing quadrupole magnets. A concept for a superconducting quadrupole array, using many simple racetrack coils, was developed at LLNL. Two, single-bore quadrupole prototypes of the same design, with distinctly different conductor, were designed, built, and tested. Both prototypes reached their short sample currents with little or no training. Magnet design, and test results, are presented and discussed.

  16. Solid state proton imaging detected by quadrupole resonance.

    PubMed

    Perlo, J; Casanova, F; Robert, H; Pusiol, D J

    2001-06-01

    A double resonance method for imaging of solid materials containing quadrupole nuclei via the coupled protons is reported. The technique uses a static field gradient to encode the position on the protons and the method of double resonance spin-echo to detect the occurrence of proton resonances by affecting the zero-field echo signal from the quadrupole system. The double resonance imaging method offers the advantages of higher spatial resolution and straightforward image reconstruction for powder samples compared with rotating-frame and Zeeman-perturbated nuclear quadrupole resonance encoding techniques. Copyright 2001 Academic Press.

  17. Acoustic monopoles, dipoles, and quadrupoles: An experiment revisited

    NASA Astrophysics Data System (ADS)

    Russell, Daniel A.; Titlow, Joseph P.; Bemmen, Ya-Juan

    1999-08-01

    A simple and inexpensive demonstration of acoustic monopole, dipole, and quadrupole sources utilizes four 4-in. boxed loudspeakers and a homemade switch box. The switch box allows the speakers to be driven in any combination of phase relationships. Placing the speakers on a rotating stool allows students to measure directivity patterns for monopole, dipole, and quadrupole speaker combinations. Stacking the speakers in a square, all facing the same direction, allows students to aurally compare the frequency and amplitude dependence of sound radiation from monopoles, dipoles, and quadrupoles.

  18. Emission of nuclear quadrupole resonance from polycrystalline hexamethylenetetramine.

    PubMed

    Ota, G; Itozaki, H

    2008-03-01

    The angular dependence of the nuclear quadrupole resonance (NQR) signal intensity emitted from polycrystalline hexamethylenetetramine has been analytically investigated for all directions for non-contact detection of chemicals by nuclear quadrupole resonance. The field pattern of the NQR signal from a column sample was measured. The emitted patterns were the same as that from a united single magnetic dipole, which fitted well to the estimation based on quadrupole principle axis system. This result is helpful to design an antenna for NQR remote detection.

  19. The effective temperature of ions stored in a linear quadrupole ion trap mass spectrometer.

    PubMed

    Donald, William A; Khairallah, George N; O'Hair, Richard A J

    2013-06-01

    The extent of internal energy deposition into ions upon storage, radial ejection, and detection using a linear quadrupole ion trap mass spectrometer is investigated as a function of ion size (m/z 59 to 810) using seven ion-molecule thermometer reactions that have well characterized reaction entropies and enthalpies. The average effective temperatures of the reactants and products of the ion-molecule reactions, which were obtained from ion-molecule equilibrium measurements, range from 295 to 350 K and do not depend significantly on the number of trapped ions, m/z value, ion trap q z value, reaction enthalpy/entropy, or the number of vibrational degrees of freedom for the seven reactions investigated. The average of the effective temperature values obtained for all seven thermometer reactions is 318 ± 23 K, which indicates that linear quadrupole ion trap mass spectrometers can be used to study the structure(s) and reactivity of ions at near ambient temperature.

  20. (14) N nuclear quadrupole resonance study of piroxicam: confirmation of new polymorphic form V.

    PubMed

    Lavrič, Zoran; Pirnat, Janez; Lužnik, Janko; Puc, Uroš; Trontelj, Zvonko; Srčič, Stane

    2015-06-01

    A new polymorphic crystal form of piroxicam was discovered while preparing crystalline samples of piroxicam for (14) N nuclear quadrupole resonance (NQR) analysis. The new crystal form, designated as V, was prepared by evaporative recrystallization from dichloromethane. Three known polymorphic forms (I, II, and III) were also prepared. Our aim was to apply (14) N NQR to characterize the new polymorphic form of piroxicam and compare the results with those of the other known polymorphic forms. Additional analytical methods used for characterization were X-ray powder diffraction (XRPD), thermal analysis, and vibrational spectroscopy. For the first time, a complete set of nine characteristic (14) N NQR frequencies was found for each prepared polymorph of piroxicam. The consistent set of measured frequencies and calculated characteristic quadrupole parameters found for the new polymorphic form V is a convincing evidence that we are dealing with a new form. The already known piroxicam polymorphic forms were characterized similarly. The XRPD results were in accordance with the conclusions of (14) N NQR analysis. The performed study clearly demonstrates a strong potential of (14) N NQR method to be applied as a highly discriminative spectroscopic analytical tool to characterize polymorphic forms.

  1. Observation of b2 symmetry vibrational levels of the SO2C 1B2 state: Vibrational level staggering, Coriolis interactions, and rotation-vibration constants

    SciTech Connect

    Park, G. Barratt; Jiang, Jun; Saladrigas, Catherine A.; Field, Robert W.

    2016-04-14

    Here, the C 1B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. However, low-lying levels with odd quanta of antisymmetric stretch (b2 vibrational symmetry) have not previously been observed because transitions into these levels from the zero-point level of the X~ state are vibronically forbidden. We use IR-UV double resonance to observe the b2 vibrational levels of the C state below 1600 cm–1 of vibrational excitation. This enables a direct characterization of the vibrational level staggering that results from the double-minimum potential. In addition, it allows us to deperturb the strong c-axis Coriolis interactions between levels of a1 and b2 vibrational symmetry, and to determine accurately the vibrational dependence of the rotational constants in the distorted C electronic state.

  2. Observation of b2 symmetry vibrational levels of the SO2C 1B2 state: Vibrational level staggering, Coriolis interactions, and rotation-vibration constants

    SciTech Connect

    Park, G. Barratt; Jiang, Jun; Saladrigas, Catherine A.; Field, Robert W.

    2016-04-14

    Here, the C 1B2 state of SO2 has a double-minimum potential in the antisymmetric stretch coordinate, such that the minimum energy geometry has nonequivalent SO bond lengths. However, low-lying levels with odd quanta of antisymmetric stretch (b2 vibrational symmetry) have not previously been observed because transitions into these levels from the zero-point level of the X~ state are vibronically forbidden. We use IR-UV double resonance to observe the b2 vibrational levels of the C state below 1600 cm–1 of vibrational excitation. This enables a direct characterization of the vibrational level staggering that results from the double-minimum potential. In addition, it allows us to deperturb the strong c-axis Coriolis interactions between levels of a1 and b2 vibrational symmetry, and to determine accurately the vibrational dependence of the rotational constants in the distorted C electronic state.

  3. Vibronic Contributions to Ligand-Induced Pseudo-Quadrupole Absorption of Rare-Earth Ions

    NASA Astrophysics Data System (ADS)

    Judd, B. R.

    1980-01-01

    The intensities of certain lines in the absorption spectra of rare-earth or actinide ions are very sensitive to the neighboring ligands. The contributions to these intensities coming from vibronic transitions (combined electronic and vibrational transitions) are calculated by tensorial techniques with particular reference to octahedral complexes. The expansions that are used possess leading terms that indicate that the strongest vibronic lines should be associated with electronic transitions that satisfy the selection rules on J (the total angular momentum) that are identical to those for quadrupole radiation. General agreement is obtained with the recent work of Faulkner and Richardson on the transition 7F0 → 5D2 of Eu3+, though some of the approximations and assumptions, as well as much of the mathematics, are different.

  4. Formation of limit-periodic structures by quadrupole particles confined to a triangular lattice

    NASA Astrophysics Data System (ADS)

    Rutkowski, David M.; Marcoux, Catherine; Socolar, Joshua E. S.; Hall, Carol K.

    2017-01-01

    We have performed Monte Carlo (MC) simulations on two-dimensional systems of quadrupole particles confined to a triangular lattice in order to determine the conditions that permit the formation of a limit-periodic phase. We have found that limit-periodic structures form only when the rotations of the particles are confined to a set of six orientations aligned with the lattice directions. Related structures including striped and unidirectional rattler phases form when π /π 6 rotations or continuous rotations are allowed. Order parameters signaling the formation of the limit-periodic structure and related structures are measured as a function of temperature. Our findings on the formation of the limit-periodic structure elucidate features relevant to the experimental creation of such a structure, which is expected to have interesting vibrational and electromagnetic modes.

  5. The vibrational energy levels of ammonia

    NASA Astrophysics Data System (ADS)

    Handy, Nicholas C.

    1999-02-01

    A variational 6-dimensional method is used to determine the low lying vibrational energy levels of ammonia. The six internal coordinates were chosen to be appropriate for the symmetry and inversion motion of the molecule; they were the three NH bond lengths, r1,r2,r3, the unique angle beta which each bond makes with the trisector of them, and two (of the three) angles, theta2 and theta3, between the bonds when projected on to a plane perpendicular to the trisector. The Wilson G matrix was determined for these internal coordinates both by computer algebra and by hand. An appropriate Jacobian for the motion was determined and the full Hermitian kinetic energy operator was obtained using the Podolsky transformation. Expansion functions were in the usual product form. Special attention was given to the , theta2,theta3 expansion functions so that appropriate A1,A2 and E symmetry vibrational modes were obtained explicitly. Matrix elements of the kinetic energy operator were expressed in terms of one-dimensional integrals. Variational calculations have been performed with two six-dimensional surfaces: (i) that due to Martin, Lee and Taylor; and (ii) that due to Spirko and Kraemer. Although some of the vibrational levels for both surfaces are accurate, both have inadequacies: (a) because it is a Taylor expansion about an equilibrium, based on ab initio calculations, with no attention paid to planarity; and (b) because the non-inversion part of the surface was treated perturbatively in its derivation, and in fact some of the quartic displacement powers have negative coefficients. Therefore, neither surface gave good results overall, and there is a need for a refined 6 dimensional NH surface.

  6. Beam based alignment of C-shaped quadrupole magnets

    SciTech Connect

    Portmann, G.; Robin, D.

    1998-06-01

    Many storage rings have implemented a method of finding the positional offset between the electrical center of the beam position monitors (BPM) and the magnetic center of the adjacent quadrupole magnets. The algorithm for accomplishing this is usually based on modulating the current in the quadrupole magnet and finding the beam position that minimizes the orbit perturbation. When the quadrupole magnet is C-shaped, as it is for many light sources, the modulation method can produce an erroneous measurement of the magnetic center in the horizontal plane. When the current in a C-shaped quadrupole is changed, there is an additional dipole component in the vertical field. Due to nonlinearities in the hysteresis cycle of the C-magnet geometry, the beam-based alignment technique at the Advanced Light Source (ALS) deviated horizontally by .5 mm from the actual magnetic center. By modifying the technique, the offsets were measured to an accuracy of better than 50 {micro}m.

  7. PRINCIPLE OF SKEW QUADRUPOLE MODULATION TO MEASURE BETATRON COUPLING.

    SciTech Connect

    LUO.Y.PILAT,F.ROSER,T.ET AL.

    2004-07-05

    The measurement of the residual betatron coupling via skew quadrupole modulation is a new diagnostics technique that has been developed and tested at the Relativistic Heavy Ion Collider (RHIC) as a very promising method for the linear decoupling on the ramp. By modulating the strengths of different skew quadrupole families the two eigentunes are precisely measured with the phase lock loop system. The projections of the residual coupling coefficient onto the skew quadrupole coupling modulation directions are determined. The residual linear coupling could be corrected according to the measurement. An analytical solution for skew quadrupole modulation based on Hamiltonian perturbation approximation is given, and simulation code using smooth accelerator model is also developed. Some issues concerning the practical applications of this technique are discussed.

  8. Electro-Magnetic Quadrupole Magnets in the LCLS FEL Undulator

    SciTech Connect

    Emma, P.

    2005-01-31

    We discuss various aspects of electro-magnetic quadrupole (EMQ) magnets for the LCLS FEL undulator, including their utility in beam-based alignment (BBA), magnet design issues, and impact on tunnel environment, reliability, and cost.

  9. Quadrupole electromagnetic radiation of an oscillating charged droplet

    NASA Astrophysics Data System (ADS)

    Grigor'ev, A. I.; Kolbneva, N. Yu.; Shiryaeva, S. O.

    2017-06-01

    Analytical calculations using the first order of smallness with respect to dimensionless amplitude of oscillations show that the intensity of electromagnetic radiation of a charged droplet is determined by time-dependent quadrupole moment.

  10. Thermal Analysis of the ILC Superconductin Quadrupole

    SciTech Connect

    Ross, Ian; /Rose-Hulman Inst., Terre Haute /SLAC

    2006-09-13

    Critical to a particle accelerator's functioning, superconducting magnets serve to focus and aim the particle beam. The Stanford Linear Accelerator Center (SLAC) has received a prototype superconducting quadrupole designed and built by the Centro de Investigaciones Energ{acute e}ticas, Medioambientales y Tecnol{acute o}gicas (CIEMAT) to be evaluated for the International Linear Collider (ILC) project. To ensure proper functioning of the magnet, the device must be maintained at cryogenic temperatures by use of a cooling system containing liquid nitrogen and liquid helium. The cool down period of a low temperature cryostat is critical to the success of an experiment, especially a prototype setup such as this one. The magnet and the dewar each contain unique heat leaks and material properties. These differences can lead to tremendous thermal stresses. The system was analyzed mathematically, leading to ideal liquid helium and liquid nitrogen flow rates during the magnet's cool-down to 4.2 K, along with a reasonable estimate of how long this cool-down will take. With a flow rate of ten gaseous liters of liquid nitrogen per minute, the nitrogen shield will take approximately five hours to cool down to 77 K. With a gaseous helium flow rate of sixty liters per minute, the magnet will take at least nineteen hours to cool down to a temperature of 4.2 K.

  11. Adjustable rare earth quadrupole drift tube magnets

    SciTech Connect

    Feinberg, B.; Tanabe, J.; Halbach, K.; Koehler, G.; Green, M.I.

    1987-03-01

    A prototype permanent-magnet drift tube quadrupole with adjustable field strength has been constructed and tested. The magnet uses iron pole pieces to provide the required field shape along with rare earth permanent-magnet material (samarium cobalt) to energize the magnet. A unique feature of the configuration is the adjustability of the field, accomplished by rotating the outer rings consisting of permanent magnets and iron. In contrast with a previous prototype magnet, this new design uses ball bearings in place of slide bearings to eliminate potential failures. The rotation is now achieved with a bevel gear mechanism. The prototype design also incorporates a new drift tube shell vacuum seal to allow easy disassembly. Tests were made of the magnetic properties and the mechanical performance of this magnet. Field errors are extremely small, and the magnet passed an accelerated ten year lifetime test. It is planned to use this type of magnet to replace 24 of the SuperHILAC prestripper drift tubes.

  12. Nuclear spin squeezing via electric quadrupole interaction

    NASA Astrophysics Data System (ADS)

    Aksu Korkmaz, Yaǧmur; Bulutay, Ceyhun

    2016-01-01

    Control over nuclear-spin fluctuations is essential for processes that rely on preserving the quantum state of an embedded system. For this purpose, squeezing is a viable alternative, so far that has not been properly exploited for the nuclear spins. Of particular relevance in solids is the electric quadrupole interaction (QI), which operates on nuclei having spin higher than 1/2. In its general form, QI involves an electric-field gradient (EFG) biaxiality term. Here, we show that as this EFG biaxiality increases, it enables continuous tuning of single-particle squeezing from the one-axis twisting to the two-axis countertwisting limits. A detailed analysis of QI squeezing is provided, exhibiting the intricate consequences of EFG biaxiality. The initial states over the Bloch sphere are mapped out to identify those favorable for fast initial squeezing, or for prolonged squeezings. Furthermore, the evolution of squeezing in the presence of a phase-damping channel and an external magnetic field are investigated. We observe that dephasing drives toward an antisqueezed terminal state, the degree of which increases with the spin angular momentum. Finally, QI squeezing in the limiting case of a two-dimensional EFG with a perpendicular magnetic field is discussed, which is of importance for two-dimensional materials, and the associated beat patterns in squeezing are revealed.

  13. Quadrupole resonance spectroscopic study of narcotic materials

    NASA Astrophysics Data System (ADS)

    Rayner, Timothy J.; West, Rebecca; Garroway, Allen N.; Lyndquist, R.; Yesinowski, James P.

    1997-02-01

    Bulk narcotic detection systems based upon Quadrupole Resonance Analysis (QRA) technology have a major advantage over imaging technologies, in that QRA is chemical-specific and consequently has a lower rate of false alarms. QRA is a magnetic resonance technology which occurs as a result of the inherent molecular properties of the atomic nuclei in crystalline and amorphous solids. The QRA response is characterized by 1) the precessional frequency of the nucleus, and 2) the nature of the electric field gradient experienced by the nucleus,due to its molecular environment. Another important detection parameter is linewidth, resonant quality. All of these parameters depend on sample purity and manufacturing process. Quantum Magnetics recently carried out a study on the QRA signatures of various narcotic materials with the support of the US Army, US Customs, and the Office of National Drug Control Policy. The aim of the study was to fully characterize the variation in QRA spectroscopic parameters of different samples of cocaine base and cocaine hydrochloride. The results from this study ar discussed here.

  14. Optical emission and vibrational modes of uniform pentacene monolayers (*)

    NASA Astrophysics Data System (ADS)

    He, Rui; Tassi, Nancy; Blanchet, Graciela; Pinczuk, Aron

    2006-03-01

    Pentacene monolayers are probed by photoluminescence and resonant Raman spectroscopies below 10K. Monolayers grown on polymeric substrate of poly-alpha-methyl-styrene (PAMS) exhibit high uniformity within micron size clusters. These films show sharp exciton luminescence bands, and the energy of the exciton optical emission displays a red-shift as the average film thickness increases. The large resonance enhancements of Raman scattering intensities enable the measurements of low-lying (40- 200cm-1) optical lattice vibrations from these monolayers. These experiments demonstrate that luminescence and resonant Raman scattering from single pentacene monolayers are venues for probing 2D properties, studies of interface effects, and thin film characterization. (*) Supported primarily by the Nanoscale Science and Engineering Initiative of the National Science Foundation under NSF Award No. CHE-0117752 and by the New York State Office of Science, Technology, and Academic Research (NYSTAR), and by a research grant of the W. M. Keck Foundation.

  15. Development of electrostatic quadrupoles for heavy ion fusion

    SciTech Connect

    Faltens, A.; Seidl, P.

    1996-03-01

    High-voltage electrostatic quadrupoles are used for focusing ion beams at low energies in the induction linac approach to heavy ion driven inertial confinement fusion for the production of electrical power. The transportable beam line charge density depends linearly on the operating voltage of the quadrupoles, so an experimental program was conducted to find the voltage break-down dependence on the overall size of the quadrupoles which would then allow determination of the best geometry and operating voltage. The quadrupole electrodes are usually stainless steel cylinders with hemispherical end caps, mounted on stainless steel end plates. The end plates are precisely positioned with respect to each other and the vacuum chamber with alumina insulators with shielded triple points. It is advantageous for beam transport to employ an array of multiple beams for which a rather large number of interdigitated electrodes forms an array of quadrupoles. The trade-offs between very large numbers of small channels and a smaller number of large channels, and the dependence of the choice on the voltage break-down dependence is discussed. With present understanding, the optimum is about 100 beamlets focused with quadrupoles which have a beam aperture radius of about 2.3 cm and are operated with about 150 kV between electrodes.

  16. Dynamics of a charged drop in a quadrupole electric field

    NASA Astrophysics Data System (ADS)

    Das, Sudip; Mayya, Y. S.; Thaokar, Rochish

    2015-07-01

    Quadrupole electric fields are commonly employed for confining charged conducting drops in Paul traps for studying Rayleigh instability characteristics. We investigate the effect of these fields on the deformation and stability characteristics of a charged liquid drop, using the axisymmetric boundary integral method (BIM). Different combinations of the amount of charge and strength of the electric field give rise to different equilibrium shapes. Interestingly, unlike in the case of uniform fields, stable oblate equilibrium drop shapes are sustained in quadrupole fields. In a positive endcap configuration of the quadrupole setup a drop carrying a small negative charge displays a transition from oblate to prolate as the field strength increases. On the other hand, for the case of a highly charged drop, a shift in the Rayleigh critical charge is observed in the presence of a weak quadrupole field. The Rayleigh instability displays imperfect transcritical bifurcation characteristics with respect to imposed prolate and oblate perturbations. Results are of significance in i) interpreting deformation and the Rayleigh stability effects using Paul traps with quadrupole fields, ii) designing more efficient quadrupole-field-based technologies for emulsification of water in oil.

  17. Free exciton emission and vibrations in pentacene monolayers

    NASA Astrophysics Data System (ADS)

    He, Rui

    2011-03-01

    Pentacene is a benchmark organic semiconductor material because of its potential applications in electronic and optoelectronic devices. Recently we demonstrated that optical and vibrational characterizations of pentacene films can be carried out down to the sub-monolayer limit. These milestones were achieved in highly uniform pentacene films that were grown on a compliant polymeric substrate. Films with thickness ranging from sub- monolayer to tens of monolayers were studied at low temperatures. The intensity of the free exciton (FE) luminescence band increases quadratically with the number of layers N when N is small. This quadratic dependence is explained as arising from the linear dependence of the intensity of absorption and the probability of emission on the number of layers N. Large enhancements of Raman scattering intensities at the FE resonance enable the first observations of low-lying lattice modes in the monolayers. The measured low- lying modes (in the 20 to 100 cm-1 range) display characteristic changes when going from a single monolayer to two layers. The Raman intensities by high frequency intra-molecular vibrations display resonance enhancement double-peaks when incident or scattered photon energies overlap the FE optical emission. The double resonances are about the same strength which suggests that Franck-Condon overlap integrals for the respective vibronic transitions have the same magnitude. The interference between scattering amplitudes in the Raman resonance reveals quantum coherence of the symmetry-split states (Davydov doublet) of the lowest intrinsic singlet exciton. These results demonstrate novel venues for ultra-thin film characterization and studies of fundamental physics in organic semiconductor structures. In collaboration with Nancy G. Tassi (Dupont), Graciela B. Blanchet (Nanoterra, Cambridge, MA), and Aron Pinczuk (Columbia University).

  18. Commissioning of helium injector for coupled radio frequency quadrupole and separated function radio frequency quadrupole accelerator.

    PubMed

    Peng, Shixiang; Chen, Jia; Ren, Haitao; Zhao, Jie; Xu, Yuan; Zhang, Tao; Zhang, Ailing; Xia, Wenlong; Gao, Shuli; Wang, Zhi; Luo, Yuting; Guo, Zhiyu; Chen, Jia'er

    2014-02-01

    A project to study a new type of acceleration structure has been launched at Peking University, in which a traditional radio frequency quadrupole (RFQ) and a separated function radio frequency quadrupole are coupled in one cavity to accelerate the He+ beam. A helium injector for this project is developed. The injector consists of a 2.45 GHz permanent magnet electron cyclotron resonance ion source and a 1.16 m long low energy beam transport (LEBT). The commissioning of this injector was carried out and an onsite test was held in June 2013. A 14 mA He+ beam with the energy of 30 keV has been delivered to the end of the LEBT, where a diaphragm with the diameter of 7 mm is located. The position of the diaphragm corresponds to the entrance of the RFQ electrodes. The beam emittance and fraction were measured after the 7 mm diaphragm. Its rms emittance is about 0.14 π mm mrad and the fraction of He+ is about 99%.

  19. Commissioning of helium injector for coupled radio frequency quadrupole and separated function radio frequency quadrupole accelerator

    SciTech Connect

    Peng, Shixiang Chen, Jia; Ren, Haitao; Zhao, Jie; Xu, Yuan; Zhang, Tao; Xia, Wenlong; Gao, Shuli; Wang, Zhi; Luo, Yuting; Guo, Zhiyu; Zhang, Ailing; Chen, Jia'er

    2014-02-15

    A project to study a new type of acceleration structure has been launched at Peking University, in which a traditional radio frequency quadrupole (RFQ) and a separated function radio frequency quadrupole are coupled in one cavity to accelerate the He+ beam. A helium injector for this project is developed. The injector consists of a 2.45 GHz permanent magnet electron cyclotron resonance ion source and a 1.16 m long low energy beam transport (LEBT). The commissioning of this injector was carried out and an onsite test was held in June 2013. A 14 mA He+ beam with the energy of 30 keV has been delivered to the end of the LEBT, where a diaphragm with the diameter of 7 mm is located. The position of the diaphragm corresponds to the entrance of the RFQ electrodes. The beam emittance and fraction were measured after the 7 mm diaphragm. Its rms emittance is about 0.14 π mm mrad and the fraction of He+ is about 99%.

  20. Surface vibrational modes in disk-shaped resonators.

    PubMed

    Dmitriev, A V; Gritsenko, D S; Mitrofanov, V P

    2014-03-01

    The natural frequencies and distributions of displacement components for the surface vibrational modes in thin isotropic elastic disks are calculated. In particular, the research is focused on even solutions for low-lying resonant vibrations with large angular wave numbers. Several families of modes are found which are interpreted as modified surface modes of an infinitely long cylinder and Lamb modes of a plate. The results of calculation are compared with the results of the experimental measurements of vibrational modes generated by means of resonant excitation in duraluminum disk with radius of ≈90 mm and thickness of 16 mm in the frequency range of 130-200 kHz. An excellent agreement between the calculated and measured frequencies is found. Measurements of the structure of the resonant peaks show splitting of some modes. About a half of the measured modes has splitting Δfsplit/fmode at the level of the order of 10(-5). The Q-factors of all modes measured in vacuum lie in the interval (2…3)×10(5). This value is typical for duraluminum mechanical resonators in the ultrasonic frequency range.

  1. Renner-Teller interactions in the vibrational autoionization of polyatomic molecules.

    PubMed

    Jungen, Ch; Pratt, S T

    2008-10-28

    Vibrational autoionization induced by the Renner-Teller interaction in linear polyatomic molecules is considered in the context of the three-state electrostatic model developed by Gauyacq and Jungen [Mol. Phys. 41, 383 (1980)]. For small interactions, simple formulas are derived for the quantum defect matrix elements and the autoionization rates in terms of the more common Renner-Teller parameters derived from spectroscopic analyses of low-lying Rydberg states. These formulas should provide guidance for empirical fitting of quantum defect parameters to spectra of high Rydberg states. Consideration of typical values of the Renner-Teller parameters also allows the estimation of vibrational autoionization rates induced by these interactions. These estimates support the validity of the Deltav=-1 propensity rule for vibrational autoionization. Constraints on the vibrational autoionization rates for the symmetric stretching vibration are also discussed. In the following paper, electron capture by polyatomic molecular ions into vibrationally autoionizing Rydberg states is considered from the same perspective, and a simple formula is derived to allow the estimation of the effect of this process on dissociative recombination cross sections.

  2. Renner-Teller interactions in the vibrational autoionization of polyatomic molecules.

    SciTech Connect

    Jungen, Ch.; Pratt, S. T.; Chemical Sciences and Engineering Division; Universite de Paris-Sud

    2008-01-01

    Vibrational autoionization induced by the Renner-Teller interaction in linear polyatomic molecules is considered in the context of the three-state electrostatic model developed by Gauyacq and Jungen [Mol. Phys. 41, 383 (1980)]. For small interactions, simple formulas are derived for the quantum defect matrix elements and the autoionization rates in terms of the more common Renner-Teller parameters derived from spectroscopic analyses of low-lying Rydberg states. These formulas should provide guidance for empirical fitting of quantum defect parameters to spectra of high Rydberg states. Consideration of typical values of the Renner-Teller parameters also allows the estimation of vibrational autoionization rates induced by these interactions. These estimates support the validity of the {Delta}v = -1 propensity rule for vibrational autoionization. Constraints on the vibrational autoionization rates for the symmetric stretching vibration are also discussed. In the following paper, electron capture by polyatomic molecular ions into vibrationally autoionizing Rydberg states is considered from the same perspective, and a simple formula is derived to allow the estimation of the effect of this process on dissociative recombination cross sections.

  3. Noncontact Electromagnetic Vibration Source

    NASA Technical Reports Server (NTRS)

    Namkung, Min; Fulton, James P.; Wincheski, Buzz A.

    1994-01-01

    Metal aircraft skins scanned rapidly in vibration tests. Relatively simple combination of permanent magnets and electromagnet serves as noncontact vibration source for nondestructive testing of metal aircraft skins. In test, source excites vibrations, and vibration waveforms measured, then analyzed for changes in resonances signifying cracks and other flaws.

  4. Flow-induced vibration

    SciTech Connect

    Blevins, R.D.

    1990-01-01

    This book reports on dimensional analysis; ideal fluid models; vortex-induced vibration; galloping and flutter; instability of tube and cylinder arrays; vibrations induced by oscillating flow; vibration induced by turbulence and sound; damping of structures; sound induced by vortex shedding; vibrations of a pipe containing a fluid flow; indices. It covers the analysis of the vibrations of structures exposed to fluid flows; explores applications for offshore platforms and piping; wind-induced vibration of buildings, bridges, and towers; and acoustic and mechanical vibration of heat exchangers, power lines, and process ducting.

  5. Millimeter-wave and Submillimeter-wave Spectra of Aminoacetonitrile in the Three Lowest Vibrational Excited States

    NASA Astrophysics Data System (ADS)

    Degli Esposti, Claudio; Dore, Luca; Melosso, Mattia; Kobayashi, Kaori; Fujita, Chiho; Ozeki, Hiroyuki

    2017-06-01

    It is important to study possible precursors of amino acids such as glycine to enable future searches in interstellar space. Aminoacetonitrile (NH2CH2CN) is one of the most feasible molecules for this purpose. This molecule was already detected toward Sgr B2(N). Aminoacetonitrile has a few low-lying vibrational excited states, and transitions within these states may be found in space. In this study, the pure-rotational transitions in the three lowest vibrational states in the 80-450 GHz range have been assigned and analyzed. It was found to be very important to include Coriolis coupling between the two lowest vibrational fundamentals, while the third one was unperturbed. The partition function was evaluated considering these new results.

  6. Vibrational energy levels of the simplest Criegee intermediate (CH2OO) from full-dimensional Lanczos, MCTDH, and MULTIMODE calculations

    NASA Astrophysics Data System (ADS)

    Yu, Hua-Gen; Ndengue, Steve; Li, Jun; Dawes, Richard; Guo, Hua

    2015-08-01

    Accurate vibrational energy levels of the simplest Criegee intermediate (CH2OO) were determined on a recently developed ab initio based nine-dimensional potential energy surface using three quantum mechanical methods. The first is the iterative Lanczos method using a conventional basis expansion with an exact Hamiltonian. The second and more efficient method is the multi-configurational time-dependent Hartree (MCTDH) method in which the potential energy surface is refit to conform to the sums-of-products requirement of MCTDH. Finally, the energy levels were computed with a vibrational self-consistent field/virtual configuration interaction method in MULTIMODE. The low-lying levels obtained from the three methods are found to be within a few wave numbers of each other, although some larger discrepancies exist at higher levels. The calculated vibrational levels are very well represented by an anharmonic effective Hamiltonian.

  7. Vibrational energy levels of the simplest Criegee intermediate (CH2OO) from full-dimensional Lanczos, MCTDH, and MULTIMODE calculations.

    PubMed

    Yu, Hua-Gen; Ndengue, Steve; Li, Jun; Dawes, Richard; Guo, Hua

    2015-08-28

    Accurate vibrational energy levels of the simplest Criegee intermediate (CH2OO) were determined on a recently developed ab initio based nine-dimensional potential energy surface using three quantum mechanical methods. The first is the iterative Lanczos method using a conventional basis expansion with an exact Hamiltonian. The second and more efficient method is the multi-configurational time-dependent Hartree (MCTDH) method in which the potential energy surface is refit to conform to the sums-of-products requirement of MCTDH. Finally, the energy levels were computed with a vibrational self-consistent field/virtual configuration interaction method in MULTIMODE. The low-lying levels obtained from the three methods are found to be within a few wave numbers of each other, although some larger discrepancies exist at higher levels. The calculated vibrational levels are very well represented by an anharmonic effective Hamiltonian.

  8. Higher order parametric excitation modes for spaceborne quadrupole mass spectrometers

    SciTech Connect

    Gershman, D. J.; Block, B. P.; Rubin, M.; Zurbuchen, T. H.; Benna, M.; Mahaffy, P. R.

    2011-12-15

    This paper describes a technique to significantly improve upon the mass peak shape and mass resolution of spaceborne quadrupole mass spectrometers (QMSs) through higher order auxiliary excitation of the quadrupole field. Using a novel multiresonant tank circuit, additional frequency components can be used to drive modulating voltages on the quadrupole rods in a practical manner, suitable for both improved commercial applications and spaceflight instruments. Auxiliary excitation at frequencies near twice that of the fundamental quadrupole RF frequency provides the advantages of previously studied parametric excitation techniques, but with the added benefit of increased sensed excitation amplitude dynamic range and the ability to operate voltage scan lines through the center of upper stability islands. Using a field programmable gate array, the amplitudes and frequencies of all QMS signals are digitally generated and managed, providing a robust and stable voltage control system. These techniques are experimentally verified through an interface with a commercial Pfeiffer QMG422 quadrupole rod system. When operating through the center of a stability island formed from higher order auxiliary excitation, approximately 50% and 400% improvements in 1% mass resolution and peak stability were measured, respectively, when compared with traditional QMS operation. Although tested with a circular rod system, the presented techniques have the potential to improve the performance of both circular and hyperbolic rod geometry QMS sensors.

  9. Higher order parametric excitation modes for spaceborne quadrupole mass spectrometers

    NASA Astrophysics Data System (ADS)

    Gershman, D. J.; Block, B. P.; Rubin, M.; Benna, M.; Mahaffy, P. R.; Zurbuchen, T. H.

    2011-12-01

    This paper describes a technique to significantly improve upon the mass peak shape and mass resolution of spaceborne quadrupole mass spectrometers (QMSs) through higher order auxiliary excitation of the quadrupole field. Using a novel multiresonant tank circuit, additional frequency components can be used to drive modulating voltages on the quadrupole rods in a practical manner, suitable for both improved commercial applications and spaceflight instruments. Auxiliary excitation at frequencies near twice that of the fundamental quadrupole RF frequency provides the advantages of previously studied parametric excitation techniques, but with the added benefit of increased sensed excitation amplitude dynamic range and the ability to operate voltage scan lines through the center of upper stability islands. Using a field programmable gate array, the amplitudes and frequencies of all QMS signals are digitally generated and managed, providing a robust and stable voltage control system. These techniques are experimentally verified through an interface with a commercial Pfeiffer QMG422 quadrupole rod system. When operating through the center of a stability island formed from higher order auxiliary excitation, approximately 50% and 400% improvements in 1% mass resolution and peak stability were measured, respectively, when compared with traditional QMS operation. Although tested with a circular rod system, the presented techniques have the potential to improve the performance of both circular and hyperbolic rod geometry QMS sensors.

  10. Theoretical investigation of flute modes in a magnetic quadrupole

    SciTech Connect

    Wu, H.S.

    1988-01-01

    This research developed theories and conducted numerical investigations of electrostatic flute modes in a plasma confined in a magnetic quadrupole. Chapter I presents the discussion of relevant background. Chapter II contains a brief discussion of the basic flute-mode operator L{sub 0} for intermediate- and low-frequency regimes. Chapter III develops a simple theory for a flute mode with frequency between the electron and ion bounce frequencies in the uniform density and temperature regions of a magnetic quadrupole. The frequency is predicted to be inversely proportional to the wave number. Chapter IV describes the kinetic approach. Chapter V contains the derivation of an eigenvalue equation for electrostatic waves with frequencies below the ion frequency in the private flux region of a magnetic quadrupole. Chapter VI develops a theory for electrostatic waves with frequency below the ion bounce frequency in the shared flux region of a magnetic quadrupole. Chapter VII contains the derivation of a dispersion equation for flute modes with frequencies between the electron and ion bounce frequencies in a plasma confined to a magnetic quadrupole. Chapter VIII presents a summary of the research described.

  11. Theoretical investigation of flute modes in a magnetic quadrupole

    SciTech Connect

    Wu, H.S.

    1988-01-01

    The objective of this research is to develop theories and conduct numerical investigations of electrostatic flute modes in a plasma confined in magnetic quadrupole. Chapter I presents the discussion of relevant background. Chapter II contains a brief discussion of the basic flute-mode operator L{sub 0} for intermediate- and low frequency regimes. Chapter III develops a simple theory for a flute mode with frequency between the electron and ion bounce frequencies in the uniform density and temperature regions of a magnetic quadrupole. Chapter IV describes the kinetic approach. Chapter V contains the derivation of an eigenvalue equation for electrostatic waves with frequencies below the ion frequency in the private flux region of a magnetic quadrupole. Chapter VI develops a theory for electrostatic waves with frequency below the ion bounce frequency in the shared flux region of a magnetic quadrupole. Chapter VII contains the derivation of a dispersion equation for flute modes with frequencies between the electron and ion ounce frequencies in a plasma confined to a magnetic quadrupole. Two intermediate-frequency modes are predicted.

  12. Nuclear Quadrupole Resonance Study of Potassium - - Chloride.

    NASA Astrophysics Data System (ADS)

    Ramia, Maximo Elias

    Fast Fourier transform nuclear quadrupole resonance (NQR) was used to study the cubic antifluorite crystal potassium hexacloro-osmate, K(,2)OsCl(,6). The study of the ('35)Cl and ('37)Cl resonances were performed on three samples of K(,2)OsCl(,6), a powder sample, a powder sample recrystallized from D(,2)O and a single crystal sample. The studies were carried out in the temperature range 300 to 6K. A detailed study of the ('35)Cl and ('37)Cl NQR lineshapes, in the temperature range 70 to 300K, showed that the lineshapes reflect the strain fields produced by lattice dislocations and point defects. The temperature evolution of these strain fields give rise to a satellite line which previously was attributed to H('+) ion impurities present in the samples. A comprehensive study of the temperature evolution of the NQR spectrum in the vicinity of the phase transition revealed a drop of line intensity and the progressive appearance of an extra broad resonance component. Both effects are associated with the existence of precursor dynamic clusters at temperatures higher than T(,C). Qualitatively similar but quantitatively different behaviour was observed in the powder and single crystal samples. Although the precursor clusters are an intrinsic property of the phrase transition, their detailed dynamics is sample independent. A NQR study of the tetragonal phase showed that at the lowest temperature the ratio of line intensities is 2:1. The phase shift effect previously observed in the tetragonal phase of K(,2)ReCl(,6) was also observed in K(,2)OsCl(,6). The effect has been explained as an experimental artifact introduced by the truncation of the FID due to the spectrometer dead time. Spin-lattice relaxation measurements in the cubic phase show two component relaxation in the vicinity of T(,C). The behaviour is quantitatively different in the powder and single crystal samples. The short relaxation time is associated with dynamic clusters. Spin-lattice relaxation time

  13. Anharmonic vibrational studies of L-aspartic acid using HF and DFT calculations

    NASA Astrophysics Data System (ADS)

    Alam, Mohammad Jane; Ahmad, Shabbir

    2012-10-01

    The experimental and theoretical studies on the structure, molecular properties and vibrational spectra of L-aspartic acid are presented. The molecular structure, harmonic and anharmonic vibrational frequencies, molecular properties, MEP mapping, NBO analysis and electronic spectra of L-aspartic acid have been reported. Computed geometrical parameters and anharmonic frequencies of fundamental, combination and overtone transitions were found in satisfactory agreement with the experimental data. The UV-Vis spectrum of present molecule has been recorded and the electronic properties such as HOMO and LUMO energies and few low lying excited states were carried out by using time dependent density functional theory (TD-DFT) approach. Natural Bond Orbital (NBO) analysis has been performed for analyzing charge delocalization throughout the molecule. Molecular electrostatic potential map has also been used for quantitative measure of the chemical activities of various sites of the molecule.

  14. Calculation of Dipole Transition Matrix Elements and Expectation Values by Vibrational Coupled Cluster Method.

    PubMed

    Banik, Subrata; Pal, Sourav; Prasad, M Durga

    2010-10-12

    An effective operator approach based on the coupled cluster method is described and applied to calculate vibrational expectation values and absolute transition matrix elements. Coupled cluster linear response theory (CCLRT) is used to calculate excited states. The convergence pattern of these properties with the rank of the excitation operator is studied. The method is applied to a water molecule. Arponen-type double similarity transformation in extended coupled cluster (ECCM) framework is also used to generate an effective operator, and the convergence pattern of these properties is compared to the normal coupled cluster (NCCM) approach. It is found that the coupled cluster method provides an accurate description of these quantities for low lying vibrational excited states. The ECCM provides a significant improvement for the calculation of the transition matrix elements.

  15. Cryogen free superconducting splittable quadrupole magnet for linear accelerators

    SciTech Connect

    Kashikhin, V.S.; Andreev, N.; Kerby, J.; Orlov, Y.; Solyak, N.; Tartaglia, M.; Velev, G.; /Fermilab

    2011-09-01

    A new superconducting quadrupole magnet for linear accelerators was fabricated at Fermilab. The magnet is designed to work inside a cryomodule in the space between SCRF cavities. SCRF cavities must be installed inside a very clean room adding issues to the magnet design, and fabrication. The designed magnet has a splittable along the vertical plane configuration and could be installed outside of the clean room around the beam pipe previously connected to neighboring cavities. For more convenient assembly and replacement a 'superferric' magnet configuration with four racetrack type coils was chosen. The magnet does not have a helium vessel and is conductively cooled from the cryomodule LHe supply pipe and a helium gas return pipe. The quadrupole generates 36 T integrated magnetic field gradient, has 600 mm effective length, and the peak gradient is 54 T/m. In this paper the quadrupole magnetic, mechanical, and thermal designs are presented, along with the magnet fabrication overview and first test results.

  16. Study the most favorable shapes of electrostatic quadrupole doublet lenses

    NASA Astrophysics Data System (ADS)

    Hussein, O. A.; Sise, O.

    2017-02-01

    The optical properties of an electrostatic quadrupole doublet lens with two different electrode shapes were studied with the aid of computer simulation. The optimal electrode voltages of the electrostatic quadrupole lenses which give the stigmatic image in both planes simultaneously were found for both concave cylindrical electrode shape and plan electrode shape of the operation mode: parallel to point focusing. The effect of electrode shape on the image properties was investigated, and the aberration figures were studied. The results showed that under the same operation condition and the geometrical dimensions, the changing of the electrode shape of the electrostatic quadrupole doublet lenses lead to important differences in the optical properties of the lenses and the characteristics of the systems.

  17. Stability of an aqueous quadrupole micro-trap

    DOE PAGES

    Park, Jae Hyun; Krstić, Predrag S.

    2012-01-01

    Recently demonstrated functionality of an aqueous quadrupole micro- or nano-trap opens a new avenue for applications of the Paul traps, like is confinement of a charged biomolecule which requires water environment for its chemical stability. Besides strong viscosity forces, motion of a charged particle in the aqueous trap is subject to dielectrophoretic and electrophoretic forces. In this study, we describe the general conditions for stability of a charged particle in an aqueous quadrupole trap. We find that for the typical micro-trap parameters, effects of both dielectrophoresis and electrophoresis significantly influence the trap stability. In particular, the aqueous quadrupole trap couldmore » play of a role of a synthetic virtual nanopore for the 3rd generation of DNA sequencing technology.« less

  18. Dark energy reflections in the redshift-space quadrupole.

    PubMed

    Yamamoto, Kazuhiro; Bassett, Bruce A; Nishioka, Hiroaki

    2005-02-11

    We show that the redshift-space quadrupole will be a powerful tool for constraining dark energy even if the baryon oscillations are missing from the monopole power spectrum and bias is scale and time dependent. We calculate the accuracy with which next-generation galaxy surveys such as KAOS will measure the quadrupole power spectrum, which gives the leading anisotropies in the power spectrum in redshift space due to linear velocity, and the so-called "Finger of God" and Alcock-Paczynski effects. Combining the monopole and quadrupole power spectra, in the complete absence of baryon oscillations (Omegab=0), leads to a roughly 500% improvement in constraints on dark energy compared with those from the monopole spectrum alone.

  19. Mechanical Design of a Second Generation LHC IR Quadrupole

    SciTech Connect

    Caspi, S.; Bartlett, S.E.; Dietderich, D.R.; Ferracin, P.; Gourlay, S.A.; Hafalia, R.R.; Hannaford, C.R.; Lietzke, A.F.; McInturff,A.D.; Sabbi, G.; Scanlan, R.M.

    2003-11-10

    One of the proposed options to increase the LHC luminosity is the replacement of the existing inner triplets at the Interaction Regions with new low-beta larger aperture quadrupoles operating at the same gradient. Lawrence Berkeley National Laboratory (LBNL) is carrying out preliminary studies of a large-bore Nb{sub 3}Sn quadrupole. The mechanical design presents a support structure based on the use of keys and bladders without self-supporting collars. This technology has been proven effective in several successful common coil Nb{sub 3}Sn dipoles built at LBNL, and it is for the first time applied to a cos(2{var_theta}) design. In this paper we present a detailed analysis of the quadrupole mechanical behavior, demonstrating the possibility of delivering, through this method, well-controlled coil precompression during assembly, cool-down and excitation. The study has been performed with the finite element program ANSYS.

  20. Stability of an aqueous quadrupole micro-trap

    SciTech Connect

    Park, Jae Hyun; Krstić, Predrag S.

    2012-01-01

    Recently demonstrated functionality of an aqueous quadrupole micro- or nano-trap opens a new avenue for applications of the Paul traps, like is confinement of a charged biomolecule which requires water environment for its chemical stability. Besides strong viscosity forces, motion of a charged particle in the aqueous trap is subject to dielectrophoretic and electrophoretic forces. In this study, we describe the general conditions for stability of a charged particle in an aqueous quadrupole trap. We find that for the typical micro-trap parameters, effects of both dielectrophoresis and electrophoresis significantly influence the trap stability. In particular, the aqueous quadrupole trap could play of a role of a synthetic virtual nanopore for the 3rd generation of DNA sequencing technology.

  1. Enhanced quadrupole effects for atoms in optical vortices.

    PubMed

    Lembessis, V E; Babiker, M

    2013-02-22

    We show that the normally weak optical quadrupole interaction in atoms is enhanced significantly when the atom interacts at near resonance with an optical vortex. In particular, the forces and torque acting on the atom are shown here to scale up with the square of the winding number l of the vortex. Because the integer l can be arranged to be large, this property allows for processes involving dipole-forbidden, but quadrupole-allowed, transitions in atoms, such as cesium and oxygen, to come into play. We show that the mechanical effects of vortex light on atoms involving translational and rotational motion as well as trapping should be significantly enhanced for quadrupole transitions and present novel features with useful implications for the emerging field of atomtronics.

  2. Removal of Axial Twist in RHIC Insertion Quadrupole Magnets

    NASA Astrophysics Data System (ADS)

    Cozzolino, J.; Anerella, M.; Jain, A.; Louie, W.; Muratore, P.

    1997-05-01

    The focusing triplets located on either side of the six interaction points of RHIC each consist of three 13cm aperture quadrupoles with magnetic lengths of 1.44m (Q1), 3.40m (Q2), and 2.10m (Q3). The field quality and alignment of these magnets are most critical to the performance of the accelerator. The maximum allowable axial twist of the cold mass, defined as the standard deviation in the quadrupole roll angle, is 0.5 mrad. This requirement has occasionally exceeded the capabilities of the assembly fixturing and the procedures used to complete the axial welding of the shell halves around the cold mass yoke. A corrective shell welding technique has been successfully employed to remove excessive axial twist of the 13cm quadrupoles. This ``custom straightening" method will be described along with the before and after mechanical inspection data. The magnetic results which confirm the untwisting procedure shall also be discussed.

  3. Effect of nuclear quadrupole moments on parity nonconservation in atoms

    NASA Astrophysics Data System (ADS)

    Flambaum, V. V.; Dzuba, V. A.; Harabati, C.

    2017-07-01

    Nuclei with spin I ≥1 have a weak quadrupole moment which leads to tensor contribution to the parity nonconserving interaction between nuclei and electrons. We calculate this contribution for atoms of current experiment interest Yb+, Fr, and Ra+. We have also performed order of magnitude estimates and found strong enhancement of the weak quadrupole effects due to the close levels of opposite parity in many lanthanoids (e.g., Nd, Gd, Dy, Ho, Er, Pr, Sm) and Ra. Another possibility is to measure the parity-nonconservation (PNC) transitions between the hyperfine components of the ground state of Bi. Since nuclear weak charge is dominated by neutrons this opens a way of measuring quadrupole moments of neutron distribution in nuclei.

  4. Study of a micro chamber quadrupole mass spectrometer

    SciTech Connect

    Wang Jinchan; Zhang Xiaobing; Mao Fuming; Xiao Mei; Cui Yunkang; Engelsen, Daniel den; Lei Wei

    2008-03-15

    The design of a micro chamber quadrupole mass spectrometer (MCQMS) having a small total volume of only 20 cm{sup 3}, including Faraday cup ion detector and ion source, is described. This MCQMS can resist a vacuum baking temperature of 400-500 deg. C. The quadrupole elements with a hyperbolic surface are made of a ceramic material and coated with a thin metal layer. The quadrupole mass filter has a field radius of 3 mm and a length of 100 mm. Prototypes of this new MCQMS can detect a minimum partial pressure of 10{sup -8} Pa, have a peak width of {delta}M=1 at 10% peak height from mass number 1 to 60, and show an excellent long-term stability. The new MCQMS is intended to be used in residual gas analyses of electron devices during a mutual pumping and baking process.

  5. Variable-field permanent magnet quadrupole for the SSC

    SciTech Connect

    Barlow, D.B.; Kraus, R.H. Jr.; Martinez, R.P.; Meyer, R.E.

    1993-10-01

    A set of compact variable-field permanent-magnet quadrupoles have been designed, fabricated, and tested for use In the SSC linac matching section. The quadrupoles have 24 mm-diameter apertures and 40 mm-long poles. The hybrid (permanent-magnet and iron) design, uses a fixed core of magnet material (NdFeB) and iron (C-1006) surrounded by a rotating ring of the same magnet material and iron. The quadrupole gradient-length product can be smoothly varied from a minimum of 0.7 T up to a maximum, of 4.3 T by a 90{degrees} rotation of the outer ring of iron and magnet material.

  6. An introduction to quadrupole-time-of-flight mass spectrometry.

    PubMed

    Chernushevich, I V; Loboda, A V; Thomson, B A

    2001-08-01

    A brief introduction is presented to the basic principles and application of a quadrupole-time-of-flight (TOF) tandem mass spectrometer. The main features of reflecting TOF instruments with orthogonal injection of ions are discussed. Their operation and performance are compared with those of triple quadrupoles with electrospray ionization and matrix-assisted laser desorption/ionization (MALDI) TOF mass spectrometers. Examples and recommendations are provided for all major operational modes: mass spectrometry (MS) and tandem MS (MS/MS), precursor ion scans and studies of non-covalent complexes. Basic algorithms for liquid chromatography/MS/MS automation are discussed and illustrated by two applications.

  7. Conceptual design of a quadrupole magnet for eRHIC

    SciTech Connect

    Witte, H.; Berg, J. S.

    2015-05-03

    eRHIC is a proposed upgrade to the existing Relativistic Heavy Ion Collider (RHIC) hadron facility at Brookhaven National Laboratory, which would allow collisions of up to 21 GeV polarized electrons with a variety of species from the existing RHIC accelerator. eRHIC employs an Energy Recovery Linac (ERL) and an FFAG lattice for the arcs. The arcs require open-midplane quadrupole magnets of up to 30 T/m gradient of good field quality. In this paper we explore initial quadrupole magnet design concepts based on permanent magnetic material which allow to modify the gradient during operation.

  8. Simulation of nuclear quadrupole resonance for sensor probe optimization.

    PubMed

    Shinohara, Junichiro; Sato-Akaba, Hideo; Itozaki, Hideo

    2012-01-01

    A simulation method to estimate the detection efficiency of nuclear quadrupole resonance (NQR) was proposed for optimizing a sensing probe operating at radio frequencies (RFs). It first calculates the transmitted magnetic field from the probe coil to the target sample. The nuclei make quadrupole resonance by it. We considered this nonlinear reaction to estimate NQR emission by the nuclei. Then the received NQR signal intensity from the sample at the probe coil. We calculated the efficiency by testing two different probe types (solenoid and gradiometer) and by changing the relative positions of the probe and sample. The simulation results were in good agreement with the experimental results.

  9. High and ulta-high gradient quadrupole magnets

    SciTech Connect

    Brunk, W.O.; Walz, D.R.

    1985-05-01

    Small bore conventional dc quadrupoles with apertures from 1 to 2.578cm were designed and prototypes built and measured. New fabrication techniques including the use of wire electric discharge milling (EDM) to economically generate the pole tip contours and aperture tolerances are described. Magnetic measurement data from a prototype of a 1cm aperture quadrupole with possible use in future e/sup +//e/sup -/ super colliders are presented. At a current of 400A, the lens achieved a gradient of 2.475 T/cm, and had an efficiency of 76.6%.

  10. Simultaneous quadrupole and octupole shape phase transitions in Thorium

    NASA Astrophysics Data System (ADS)

    Li, Z. P.; Song, B. Y.; Yao, J. M.; Vretenar, D.; Meng, J.

    2013-11-01

    The evolution of quadrupole and octupole shapes in Th isotopes is studied in the framework of nuclear Density Functional Theory. Constrained energy maps and observables calculated with microscopic collective Hamiltonians indicate the occurrence of a simultaneous quantum shape phase transition between spherical and quadrupole-deformed prolate shapes, and between non-octupole and octupole-deformed shapes, as functions of the neutron number. The nucleus 224Th is closest to the critical point of a double phase transition. A microscopic mechanism of this phenomenon is discussed in terms of the evolution of single-nucleon orbitals with deformation.

  11. Phase and Radial Motion in a Transverse Electric Quadrupole - Manufacturing

    SciTech Connect

    Billen, James; Crandall, Ken; Young, Lloyd

    2010-06-25

    ParmteqM comprises a group of codes (PARMTEQ, RFQUICK, CURLI, PARI, PARMTEQM, READVG and VANES) that are used to design high-performance radio-frequency quadrupole (RFQ) linacs. PARMTEQ is an acronym for "Phase and Radial Motion in a Transverse Electric Quadrupole". These codes are necessary to design the RFQ vane profile and analyze the beam performance including the effects of higher order multipole field components and image charges. Multi-particle simulations are supported in Version 3. PARMTEQM, VANES and READVG specifically provide manufacturing support to generate CNC machining instructions for the fabrication of vane profiles.

  12. Low-frequency quadrupole impedance of undulators and wigglers

    NASA Astrophysics Data System (ADS)

    Blednykh, A.; Bassi, G.; Hidaka, Y.; Smaluk, V.; Stupakov, G.

    2016-10-01

    An analytical expression of the low-frequency quadrupole impedance for undulators and wigglers is derived and benchmarked against beam-based impedance measurements done at the 3 GeV NSLS-II storage ring. The adopted theoretical model, valid for an arbitrary number of electromagnetic layers with parallel geometry, allows to calculate the quadrupole impedance for arbitrary values of the magnetic permeability μr . In the comparison of the analytical results with the measurements for variable magnet gaps, two limit cases of the permeability have been studied: the case of perfect magnets (μr→∞ ), and the case in which the magnets are fully saturated (μr=1 ).

  13. Global investigation of the fine structure of the isoscalar giant quadrupole resonance

    SciTech Connect

    Shevchenko, A.; Burda, O.; Kalmykov, Y.; Neumann-Cosel, P. von; Ponomarev, V. Yu.; Richter, A.; Wambach, J.; Carter, J.; Sideras-Haddad, E.; Cooper, G. R. J.; Fearick, R. W.; Foertsch, S. V.; Lawrie, J. J.; Neveling, R.; Smit, F. D.; Fujita, H.; Fujita, Y.; Lacroix, D.

    2009-04-15

    Fine structure in the region of the isoscalar giant quadrupole resonance (ISGQR) in {sup 58}Ni, {sup 89}Y, {sup 90}Zr, {sup 120}Sn, {sup 166}Er, and {sup 208}Pb has been observed in high-energy-resolution ({delta}E{sub 1/2}{approx_equal}35-50 keV) inelastic proton scattering measurements at E{sub 0}=200 MeV at iThemba LABS. Calculations of the corresponding quadrupole excitation strength functions performed within models based on the random-phase approximation (RPA) reveal similar fine structure when the mixing of one-particle one-hole states with two-particle two-hole states is taken into account. A detailed comparison of the experimental data is made with results from the quasiparticle-phonon model (QPM) and the extended time-dependent Hartree-Fock (ETDHF) method. For {sup 208}Pb, additional theoretical results from second RPA and the extended theory of finite Fermi systems (ETFFS) are discussed. A continuous wavelet analysis of the experimental and the calculated spectra is used to extract dominant scales characterizing the fine structure. Although the calculations agree with qualitative features of these scales, considerable differences are found between the model and experimental results and amongst different models. Within the framework of the QPM and ETDHF calculations it is possible to decompose the model spaces into subspaces approximately corresponding to different damping mechanisms. It is demonstrated that characteristic scales mainly arise from the collective coupling of the ISGQR to low-energy surface vibrations.

  14. Large energy-spread beam diagnostics through quadrupole scans

    SciTech Connect

    Frederico, Joel; Adli, Erik; Hogan, Mark; Raubenheimer, Tor

    2012-12-21

    The Facility for Advanced Accelerator and Experimental Tests (FACET) is a new user facility at the SLAC National Accelerator Laboratory, servicing next-generation accelerator experiments. The 1.5% RMS energy spread of the FACET beam causes large chromatic aberrations in optics. These aberrations necessitate updated quadrupole scan fits to remain accurate.

  15. Large energy-spread beam diagnostics through quadrupole scans

    SciTech Connect

    Frederico, Joel; Adli, Erik; Hogan, Mark; Raubenheimer, Tor

    2013-01-01

    The Facility for Advanced Accelerator and Experimental Tests (FACET) is a new user facility at the SLAC National Accelerator Laboratory, servicing next-generation accelerator experiments. The 1.5% RMS energy spread of the FACET beam causes large chromatic aberrations in optics. These aberrations necessitate updated quadrupole scan fits to remain accurate.

  16. LARP Long Quadrupole: A "Long" Step Toward an LHC

    ScienceCinema

    Giorgio Ambrosio

    2016-07-12

    The beginning of the development of Nb3Sn magnets for particle accelerators goes back to the 1960’s. But only very recently has this development begun to face the challenges of fabricating Nb3Sn magnets which can meet the requirements of modern particle accelerators. LARP (the LHC Accelerator Research Program) is leading this effort focusing on long models of the Interaction Region quadrupoles for a possible luminosity upgrade of the Large Hadron Collider. A major milestone in this development is to test, by the end of 2009, 4m-long quadrupole models, which will be the first Nb3Sn accelerator-type magnets approaching the length of real accelerator magnets. The Long Quadrupoles (LQ) are “Proof-of-Principle” magnets which are to demonstrate that Nb3Sn technology is sufficiently mature for use in high energy particle accelerators. Their design is based on the LARP Technological Quadrupole (TQ) models, under development at FNAL and LBNL, which have design gradients higher than 200 T/m and an aperture of 90 mm. Several challenges must be addressed for the successful fabrication of long Nb3Sn coils and magnets. These challenges and the solutions adopted will be presented together with the main features of the LQ magnets. Several R&D lines are participating to this effort and their contributions will be also presented.

  17. A LIGA Fabricated Quadrupole Array for Mass Spectroscopy

    NASA Technical Reports Server (NTRS)

    Jackson, K.; Wiberg, D. V.; Hecht, M. H.; Orient, O. J.; Chutjian, A.; Yee, K.; Fuerstenau, S.; Brennen, R. A.; Hruby, J.; Bonivert, W.

    1997-01-01

    A linear array of nine quadrupoles was fabricated using the LIGA process. Pole heights ranging from 1 to 3 mm were fabricated using synchrotron X-ray exposures to form free standing polymethylmethacrylate (PMMA) molds into which copper, gold or nickel were electroplated.

  18. Driving a quadrupole mass spectrometer via an isolating stage

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor); Aalami, Dean (Inventor); Darrach, Murray (Inventor); Orient, Otto (Inventor)

    2002-01-01

    Driving a quadrupole mass spectrometer includes obtaining an air core transformer with a primary and a secondary, matching the secondary to the mass spectrometer, and driving the primary based on first and second voltage levels. Driving of the primary is via an isolating stage that minimizes low level drive signal coupling.

  19. A LIGA Fabricated Quadrupole Array for Mass Spectroscopy

    NASA Technical Reports Server (NTRS)

    Jackson, K.; Wiberg, D. V.; Hecht, M. H.; Orient, O. J.; Chutjian, A.; Yee, K.; Fuerstenau, S.; Brennen, R. A.; Hruby, J.; Bonivert, W.

    1997-01-01

    A linear array of nine quadrupoles was fabricated using the LIGA process. Pole heights ranging from 1 to 3 mm were fabricated using synchrotron X-ray exposures to form free standing polymethylmethacrylate (PMMA) molds into which copper, gold or nickel were electroplated.

  20. Magnetic field data on Fermilab Energy-Saver quadrupoles

    SciTech Connect

    Schmidt, E.E.; Brown, B.C.; Cooper, W.E.; Fisk, H.E.; Gross, D.A.; Hanft, R.; Ohnuma, S.; Turkot, F.T.

    1983-03-01

    The Fermilab Energy Saver/Doubler (Tevatron) accelerator contains 216 superconducting quadrupole magnets. Before installation in the Tevatron ring, these magnets plus an additional number of spares were extensively tested at the Fermilab Magnet Test Facility (MTF). Details on the results of the tests are presented here.