Showing papers on "Quadrupole published in 2000"
TL;DR: This work describes a new type of mass analyzer which employs trapping in an electrostatic field and demonstrates high-mass resolution up to 150,000 for ions produced by laser ablation, along with high-energy acceptance and wide mass range.
Abstract: This work describes a new type of mass analyzer which employs trapping in an electrostatic field. The potential distribution of the field can be represented as a combination of quadrupole and logarithmic potentials. In the absence of any magnetic or rf fields, ion stability is achieved only due to ions orbiting around an axial electrode. Orbiting ions also perform harmonic oscillations along the electrode with frequency proportional to (m/z)-1/2. These oscillations are detected using image current detection and are transformed into mass spectra using fast FT, similarly to FT ICR. Practical aspects of the trap design are presented. High-mass resolution up to 150 000 for ions produced by laser ablation has been demonstrated, along with high-energy acceptance and wide mass range.
954 citations
TL;DR: Frequency shifts of the 199Hg+ 5d106s 2S1/2 to 5d96s2 2D5/2 electric-quadrupole transition at 282 nm due to external fields are calculated, based on a combination of measured atomic parameters and ab initio calculations.
Abstract: Frequency shifts of the (199)Hg(+) 5d (10)6s (2)S1/2 (F = 0, MF = 0) to 5d (9)6s (2 2)D5/2 (F = 2, MF = 0) electric-quadrupole transition at 282 nm due to external fields are calculated, based on a combination of measured atomic parameters and ab initio calculations. This transition is under investigation as an optical frequency standard. The perturbations calculated are the quadratic Zeeman shift, the scalar and tensor quadratic Stark shifts, and the interaction between an external electric field gradient and the atomic quadrupole moment. The quadrupole shift is likely to be the most difficult to evaluate in a frequency standard and may have a magnitude of about 1 Hz for a single ion in a Paul trap.
185 citations
TL;DR: In this paper, the rotational spectra of the complexes Ar-CuF, Ar-cuCl, and Ar -CuBr have been observed in the frequency range 5-22 GHz using a pulsed-jet cavity Fourier transform microwave spectrometer.
Abstract: The rotational spectra of the complexes Ar–CuF, Ar–CuCl, and Ar–CuBr have been observed in the frequency range 5–22 GHz using a pulsed-jet cavity Fourier transform microwave spectrometer. All the complexes are linear and rather rigid in the ground vibrational state, with the Ar–Cu stretching frequency estimated as ∼200 cm−1. Isotopic data have been used to calculate an r0 structure for Ar–CuF, while for Ar–CuCl and Ar–CuBr partial substitution structures have also been obtained. To reduce zero-point vibrational effects a double substitution method (rd) has also been employed to calculate the structures of Ar–CuCl and Ar–CuBr. The Ar–Cu distance has been found to be rather short and to range from 2.22 A in Ar–CuF to 2.30 A in Ar–CuBr. Ab initio calculations at the MP2 level of theory model the geometries and stretching frequencies well and predict an Ar–Cu bond energy in Ar–CuF of ∼47.3 kJ mol−1. Large changes in the Cu nuclear quadrupole coupling constant on complex formation show that extensive charge re...
167 citations
TL;DR: In this paper, the pure rotational spectra of Ar−AuCl and KCl have been measured using a pulsed-jet cavity Fourier transform microwave spectrometer.
Abstract: The pure rotational spectra of Ar−AuCl and Kr−AuCl have been measured using a pulsed-jet cavity Fourier transform microwave spectrometer. Both complexes have been found to be linear and are relatively rigid in their ground vibrational states. The noble gas−gold stretching frequencies have been estimated to be 198 and 161 cm-1 for Ar−AuCl and Kr−AuCl, respectively. From the isotopic data obtained, r0 structures have been calculated for both Ar−AuCl and Kr−AuCl, while a partial substitution (rs) structure has been obtained for Kr−AuCl. The Ar−Au distance has been found to be 2.47 A, while the Kr−Au distance is 2.52 A. Ab initio calculations have been performed at the MP2 level of theory on both complexes to obtain geometries, vibrational frequencies, and dissociation energies. The dissociation energies for Ar−AuCl and Kr−AuCl have been estimated to be 47 and 71 kJ mol-1, respectively. The nuclear quadrupole coupling constant of Au has been found to change significantly on complex formation (to −259.8 MHz in...
166 citations
TL;DR: In this paper, the deformation lengths for the 2 + 1 states in 10 Be and 12 Be were determined to be 1.80±0.25 fm and 2.00± 0.23 fm respectively, indicating that a tendency towards strong quadrupole deformation is preserved for these nuclei.
140 citations
TL;DR: In this article, it was shown that for valence orbitals the ZORA-4 electron density, which includes a small component density (picture-change correction) very accurately agrees with the Dirac electron density.
Abstract: The zeroth-order regular approximation (ZORA) is used for the evaluation of the electric field gradient, and hence nuclear quadrupole coupling constants, in some closed shell molecules. It is shown that for valence orbitals the ZORA-4 electron density, which includes a small component density (“picture-change correction”), very accurately agrees with the Dirac electron density. For hydrogen-like atoms exact relations between the ZORA-4 and Dirac formalism are given for the calculation of the electric field gradient. Density functional (DFT) calculations of the electric field gradients for a number of diatomic halides at the halogen nuclei Cl, Br, and I and at the metallic nuclei Al, Ga, In, Th, Cu, and Ag are presented. Scalar relativistic effects, spin–orbit effects, and the effects of picture-change correction, which introduces the small component density, are discussed. The results for the thallium halides show a large effect of spin–orbit coupling. Our ZORA-4 DFT calculations suggest adjustment of som...
112 citations
TL;DR: A generalization of the analytical theory of high harmonic generation in the long wavelength limit and in the single active electron approximation is developed taking into account the magnetic dipole and electric quadrupole interaction, which promises the extension ofHigh harmonic generation well into the sub-nm wavelength regime.
Abstract: A generalization of the analytical theory of high harmonic generation in the long wavelength limit and in the single active electron approximation is developed taking into account the magnetic dipole and electric quadrupole interaction. Quantum mechanical and classical theories are found to be in excellent agreement, which allows one to explain the influence of multipole effects in terms of an intuitive picture. For Ti:S lasers ( 0.8 mm) multipole contributions are found to be small below an intensity of about 10(17) W/cm(2), at which harmonic radiation with photon energies of several keV is generated. This promises the extension of high harmonic generation well into the sub-nm wavelength regime.
106 citations
TL;DR: In this article, a self-consistent approach was introduced to calculate molecular properties in clusters and liquids using the second-order Moller-Plesset perturbation theory (MP2) level.
98 citations
92 citations
TL;DR: In this paper, the multiconfiguration Dirac-Fock model is employed to compute the hyperfine interaction constants of the 5p4 5d 4 D7/2 levels of the xenon ion.
Abstract: The multiconfiguration Dirac-Fock model is employed to compute the hyperfine interaction constants of the 5p4 5d 4 D7/2 , 5p4 6p 4 P5/2 , 5p4 6p 2 D5/2 and 5p4 6p 4 D7/2 levels of the xenon ion The wavefunctions are obtained with the active space expansion method, where configuration state functions of a specific parity and J value are generated by substitutions from the reference configurations to an active set of orbitals The active set is then increased in a systematic way, allowing the convergence of the expectation values to be monitored The calculated electric field gradients are combined with experimentally determined electric quadrupole hyperfine constants in order to extract the nuclear electric quadrupole moment of isotope 131 of Xe, for which the value Q = -0117(6) barn is found
89 citations
TL;DR: In this paper, a novel electrode arrangement was proposed for creating a suitable axial field in a multipole ion guide without significantly reducing the m/z window, which was tested on a modified quadrupole collision cell of a MALDI-QqTOF instrument.
Abstract: Tandem instruments, such as triple-quadrupole or quadrupole-time-of-flight mass spectrometers, often use collisional damping ion guides for the purpose of cooling and focusing the primary ion beam, or as a collision cell for tandem mass spectrometry experiments. A small axial field to reduce the ion residence time in such devices can give considerable improvements in performance. Reduction of the residence time reduces adduct formation caused by unwanted gas-phase reactions and allows multiple reaction monitoring (MRM) and some other types of scan to be carried out more rapidly without the risk of reaction cross-talk. Here we propose a novel electrode arrangement for creation of a suitable axial field in a multipole ion guide without significantly reducing the m/z window. As an example, a second set of four electrodes is added to an existing quadrupole collision cell. The same DC potential is applied to all four extra electrodes, which are shaped in the longitudinal direction to create a suitable axial field inside the device. The potential of these electrodes and the DC bias of the main rods determine the axial field strength. The idea was tested on a modified quadrupole collision cell of a MALDI-QqTOF instrument and experimental results are presented here, as well as a simplified theory of operation.
TL;DR: In this article, the authors employ a multipole-Taylor expansion to investigate how tightly the gravitational potential of the quadruple-image lens MG J0414+0534 is constrained by recent VLBI observations.
Abstract: We employ a multipole-Taylor expansion to investigate how tightly the gravitational potential of the quadruple-image lens MG J0414+0534 is constrained by recent VLBI observations. These observations revealed that each of the four images of the background radio source contains four distinct components, thereby providing more numerous and more precise constraints on the lens potential than were previously available. We expand the two-dimensional lens potential using multipoles for the angular coordinate and a modified Taylor series for the radial coordinate. After discussing the physical significance of each term, we compute models of MG J0414+0534 using only VLBI positions as constraints. The best-fit model has both interior and exterior quadrupole moments as well as exterior m=3 and m=4 multipole moments. The deflector centroid in the models matches the optical galaxy position, and the quadrupoles are aligned with the optical isophotes. The radial distribution of mass could not be well constrained. We discuss the implications of these models for the deflector mass distribution and for the predicted time delays between lensed components.
TL;DR: In this paper, an ab initio investigation of the quadrupole moment, the polarizability anisotropy and the temperature-independent term entering the electric-field-gradient-induced birefringence (EFGB) of CO 2 and CS 2 is presented.
TL;DR: In this article, the nuclear electric quadrupole moments of the isotopes 26Na, 27Na, 28Na and 29Na were measured by β-NMR spectroscopy in single crystals of LiNbO3 and NaNO3.
Abstract: The nuclear electric quadrupole moments of the isotopes 26Na, 27Na, 28Na and 29Na were measured by β-NMR spectroscopy in single crystals of LiNbO3 and NaNO3. High degrees of nuclear polarization were produced by optical pumping of the sodium atoms in a fast beam with a collinear laser beam. The polarized nuclei were implanted into the crystals and NMR signals were observed in the β-decay asymmetries. Preparatory measurements also yielded improved values for the magnetic moments of 27–31Na and confirmed the spin I = 3/2 for 31Na. The results are discussed in comparison with large-basis shell model calculations.
TL;DR: In this paper, the authors employ a multipole-Taylor expansion to investigate how tightly the gravitational potential of the quadruple-image lens MG J0414+0534 is constrained by recent VLBI observations.
Abstract: We employ a multipole-Taylor expansion to investigate how tightly the gravitational potential of the quadruple-image lens MG J0414+0534 is constrained by recent VLBI observations. These observations revealed that each of the four images of the background radio source contains four distinct components, thereby providing more numerous and more precise constraints on the lens potential than were previously available. We expand the two-dimensional lens potential using multipoles for the angular coordinate and a modified Taylor series for the radial coordinate. After discussing the physical significance of each term, we compute models of MG J0414+0534 using only VLBI positions as constraints. The best-fit model has both interior and exterior quadrupole moments, as well as exterior m = 3 and m = 4 multipole moments. The deflector centroid in the models matches the optical galaxy position, and the quadrupoles are aligned with the optical isophotes. The radial distribution of mass could not be well constrained. We discuss the implications of these models for the deflector mass distribution and for the predicted time delays between lensed components.
TL;DR: In this article, a microscopic angular momentum projection after variation is used to describe quadrupole collectivity in 30,32,34 Mg and 32,34,36,38 Si.
TL;DR: Second-order [ O(k(2), k = omega/c] nondipole effects in soft-x-ray photoemission are demonstrated via an experimental and a theoretical study of angular distributions of neon valence photoelectrons in the 100-1200 eV photon-energy range.
Abstract: Second-order [ O(k(2)), k = omega/c] nondipole effects in soft-x-ray photoemission are demonstrated via an experimental and a theoretical study of angular distributions of neon valence photoelectrons in the 100-1200 eV photon-energy range. A newly derived theoretical expression for nondipolar angular distributions characterizes the second-order effects using four new parameters with primary contributions from pure-quadrupole and octupole-dipole interference terms. Independent-particle calculations of these parameters account for a significant portion of the existing discrepancy between experiment and theory for Ne 2p first-order nondipole parameters.
TL;DR: In this paper, the second-order dipole and quadrupole moments induced by an inhomogeneous monochromatic electric field of frequency 2π ∆ ∆ + ∆ 2π 2π φ φ + 2π � + 1π π 2π − 1/φ for a Si sphere lying at various distances above a dielectric substrate were calculated.
Abstract: We calculate the nonlinear dipole and quadrupole moments induced at the second-harmonic (SH) frequency $2\ensuremath{\omega}$ in a small dielectric sphere by an inhomogeneous monochromatic electric field of frequency $\ensuremath{\omega}.$ We neglect finite-size effects and assume that the selvedge region of the sphere is thin enough so that the surface may be considered locally flat. The second-order dipole displays resonances corresponding to the excitation of dipolar and quadrupolar plasmons at $\ensuremath{\omega}$ and a dipolar plasmon at $2\ensuremath{\omega},$ besides the resonances in the nonlinear surface response parameters a, b, and f. The second-order quadrupole, on the other hand, has resonances corresponding to those of a, b, and f, and to the excitation of dipolar surface plasmons at $\ensuremath{\omega}$ only. Depending on the relation between the size of the sphere and the spatial scale of variation of the field, the SH radiation may be dominated by either dipolar or quadrupolar scattering, with a crossover region. As an application, we calculate the SH scattering of a Si sphere lying at various distances above a dielectric substrate.
TL;DR: In this paper, a combination of these theoretical calculations with experimentally obtained quadrupole splittings can lead to new insight into various interesting problems, such as the determination of nuclear quadrupoles moments, investigations of samples containing impurities or other imperfections and for Na2[Fe(CN)5NO), a promising material for holographic storage applications.
Abstract: Increasing computer power and the development of user-friendly, yet highly sophisticated bandstructure programs have made it possible that theoretical EFG calculations can nowadays be performed for fairly complex materials science problems. We show that a combination of these theoretical calculations with experimentally obtained quadrupole splittings can lead to new insight into various interesting problems. This is illustrated for the determination of nuclear quadrupole moments, investigations of samples containing impurities or other imperfections and for Na2[Fe(CN)5NO], a promising material for holographic storage applications.
TL;DR: In this paper, the coordination state of the mordenite was studied using 27Al 3Q MAS NMR spectroscopy and a quadrupolar coupling constant of 5.8 MHz was estimated for the distorted tetrahedral Al.
Abstract: 27Al 3Q MAS NMR spectroscopy has been applied to study the coordination state of the species giving the 30 ppm Al NMR signal in the 27Al MAS NMR spectrum of activated mordenite materials. From the 27Al 3Q MAS NMR measurements it is evident that the broad peak at 30 ppm in the 27Al NMR spectrum of the mordenite calcined at temperatures up to 600 °C comes mainly from the distorted four-coordinated Al. By simulation a quadrupolar coupling constant of 5.8 MHz was estimated for the distorted tetrahedral Al. For samples calcined at 650 and 700 °C, a small amount of pentacoordinated Al emerges. The majority of the signal, however, arises from distorted tetrahedral Al. A two-step calcination results in a significant contribution of the pentacoordinated Al to the signal at 30 ppm. From the simulated line-shape, a quadrupole coupling constant of 6.2 MHz is obtained for the latter signal. These data show that during the calcination of the mordenite, the coordination environment at the Al centre gradually becomes distorted to give rise to the shoulder at 30 ppm. With the increase of the calcination temperature, pentacoordinated Al species form
TL;DR: In this article, a microscopic angular momentum projection after variation is used to describe quadrupole collectivity in (30,32,34,34) and (−1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,33,34), and the Hartree-Fock-Bogoliubov states obtained in the
Abstract: A microscopic angular momentum projection after variation is used to describe quadrupole collectivity in (^{30,32,34}Mg) and (^{32,34,36,38}Si). The Hartree-Fock-Bogoliubov states obtained in the quadrupole constrained mean field approach are taken as intrinsic states for the projection. Excitation energies of the first (2^{+}) states and the (B(E2,0^{+}\to 2^{+})) transition probabilities are given. A reasonable agreement with available experimental data is obtained. It is also shown that the mean field picture of those nuclei is strongly modified by the projection.
TL;DR: In this article, the conditions for the generation of pure, quadrupole modulated multipolar spin orders and for the detection of two-and four-time correlation functions were discussed.
TL;DR: The stability diagram for ion motion in a mass filter in the presence of quadrupole excitation has been constructed and the trajectories of ion motion under resonant excitation of different orders have been investigated.
TL;DR: In this paper, the authors address the question of the intrinsic quadrupole moment of the nucleon in various models and give a positive intrinsic quadrapole moment for the proton, which corresponds to a prolate deformation.
Abstract: We address the question of the intrinsic quadrupole moment ${Q}_{0}$ of the nucleon in various models. All models give a positive intrinsic quadrupole moment for the proton. This corresponds to a prolate deformation. We also calculate the intrinsic quadrupole moment of the $\ensuremath{\Delta}(1232).$ All our models lead to a negative intrinsic quadrupole moment of the ${\ensuremath{\Delta}}^{+}$ corresponding to an oblate deformation.
TL;DR: In this article, the authors derived simple approximation formulas illustrating the dependence of the efficiency of energy release in an extended disk and in a boundary layer near the NS surface on the frequency and sense of rotation for various NS equations of state.
Abstract: The energy release Ls on the surface of a neutron star (NS) with a weak magnetic field and the energy release Ld in the surrounding accretion disk depend on two independent parameters that determine its state (for example, mass M and cyclic rotation frequency f) and is proportional to the accretion rate. We derive simple approximation formulas illustrating the dependence of the efficiency of energy release in an extended disk and in a boundary layer near the NS surface on the frequency and sense of rotation for various NS equations of state. Such formulas are obtained for the quadrupole moment of a NS, for a gap between its surface and a marginally stable orbit, for the rotation frequency in an equatorial Keplerian orbit and in the marginally stable circular orbit, and for the rate of NS spinup via disk accretion. In the case of NS and disk counterrotation, the energy release during accretion can reach \(0.67\dot Mc^2 \). The sense of NS rotation is a factor that strongly affects the observed ratio of nuclear energy release during bursts to gravitational energy release between bursts in X-ray bursters. The possible existence of binary systems with NS and disk counterrotation in the Galaxy is discussed. Based on the static criterion for stability, we present a method of constructing the dependence of gravitational mass M on Kerr rotation parameter j and on total baryon mass (rest mass) m for a rigidly rotating neutron star. We show that all global NS characteristics can be expressed in terms of the function M(j, m) and its derivatives. We determine parameters of the equatorial circular orbit and the marginally stable orbit by using M(j, m) and an exact solution of the Einstein equations in a vacuum, which includes the following three parameters: gravitational mass M, angular momentum J, and quadrupole moment Ф2. Depending on Ф2, this solution can also be interpreted as a solution that describes the field of either two Kerr black holes or two Kerr disks.
TL;DR: In this paper, the quadrupole moment and dipole polarizability tensor components at the correlated complete-active-space self-consistent field (CASSCF) and completeactive space perturbation-theory(CASPT) levels for 2P states of O−, F, Ne+, Na2+, S−, Cl, Ar+, 98, K2+, Se−, Br, Kr+, Rb2+ and 3P, 1D, 1S states of 1.
Abstract: Quadrupole moment and dipole polarizability tensor components are calculated at the correlated complete-active-space self-consistent-field (CASSCF) and complete-active-space perturbation-theory (CASPT) levels for 2P states of O−, F, Ne+, Na2+, S−, Cl, Ar+, 98, K2+ , Se−, Br, Kr+, Rb2+ and 3P, 1D, 1S states of O−, F+, Ne2+, Na3+, S, Cl+, Ar2+, K3+, Se, Br+, Kr2+, Rb3+. Relativistic corrections are included perturbatively for the 34- and 35-electron systems.
TL;DR: In this paper, an intense non-neutral charged particle beam propagating in the z-direction through a periodic focusing quadrupole magnetic field with transverse focusing force, −κq(s)[xex−yey], on the beam particles was considered.
Abstract: This paper considers an intense non-neutral charged particle beam propagating in the z-direction through a periodic focusing quadrupole magnetic field with transverse focusing force, −κq(s)[xex−yey], on the beam particles. Here, s=βbct is the axial coordinate, (γb−1)mbc2 is the directed axial kinetic energy of the beam particles, qb and mb are the charge and rest mass, respectively, of a beam particle, and the oscillatory lattice coefficient satisfies κq(s+S)=κq(s), where S is the axial periodicity length of the focusing field. The particle motion in the beam frame is assumed to be nonrelativistic, and the Vlasov-Maxwell equations are employed to describe the nonlinear evolution of the distribution function fb(x,y,x′,y′,s) and the (normalized) self-field potential ψ(x,y,s)=qbφ(x,y,s)/γb3mbβb2c2 in the transverse laboratory-frame phase space (x,y,x′,y′), assuming a thin beam with characteristic radius rb≪S. It is shown that collective processes and the nonlinear transverse beam dynamics can be simulated ...
TL;DR: In this article, the ground and several collective excited states of the light nuclei were described in the framework of the angular momentum projected generator coordinate method using the quadrupole moment as collective coordinate and the Gogny force as the effective interaction.
Abstract: Properties of the ground and several collective excited states of the light nuclei ${}^{30,32,34}\mathrm{Mg}$ are described in the framework of the angular momentum projected generator coordinate method using the quadrupole moment as collective coordinate and the Gogny force as the effective interaction. The calculated excitation energies and $B(E2)$ transition probabilities agree reasonably well with experiment. The results clearly indicate that both the restoration of the rotational symmetry and the quadrupole dynamics are key ingredients for the description of the properties of the above-mentioned nuclei.
TL;DR: In this paper, the electric field near water clusters and in ice Ih using first principles calculations was studied and the predictions of an induction model based on single center multipole moments and polarizabilities of an isolated water molecule were tested.
Abstract: We have studied the electric field near water clusters and in ice Ih using first principles calculations. We employed Mo/ller–Plesset perturbation theory (MP2) for the calculations of the clusters up to and including the hexamer, and density functional theory (DFT) with a gradient dependent functional [Perdew–Wang (PW91)] for ice Ih as well as the clusters. The electric field obtained from the first principles calculations was used to test the predictions of an induction model based on single center multipole moments and polarizabilities of an isolated water molecule. We found that the fields obtained from the induction model agree well with the first principles results when the multipole expansion is carried out up to and including the hexadecapole moment, and when polarizable dipole and quadrupole moments are included. This implies that accurate empirical water interaction potential functions transferable to various environments such as water clusters and ice surfaces could be based on a single center m...
TL;DR: In this article, a generalized Landau Fermi liquid model for spherical and deformed nuclei was proposed to unify the description of the E1 photon strength functions for spherical nuclei.