Showing papers on "Quadrupole published in 1978"
TL;DR: In this article, the deuteron quadrupole coupling constants (e 2 qQ/h ) were compared to O-H and O-D stretching frequencies ( v OH and v OD ) for isotopically-dilute HDO molecules.
137 citations
25 Jul 1978
TL;DR: In this article, the results of digital simulation of ion trajectories in an RF-only quadrupole are presented, and the correspondence between simulated and experimental results aids in the understanding of the quadrupelle collision-induced dissociation process.
Abstract: Collision-induced dissociation (CID), when performed in an RF-only quadrupole is a highly efficient method of fragmenting ions. The low-energy (5-10 eV) CID process, may involve direct vibrational excitation by momentum transfer but in any case, is a very different process from the high energy (3-10 keV) electronic excitation CID process observed in MIKES and CAMS. Experimental results are presented which demonstrate the efficiency of CID fragmentation (up to 65%), the elimination of scattering losses, and the effects of varying such experimental parameters as choice and pressure of collision gas, ion velocity in the quadrupole, and quadrupole RF voltage and frequency. The appearance of the CID fragmentation spectra is roughly similar to 14 eV EI spectra. The results of digital simulation of ion trajectories in an RF-only quadrupole are presented. The correspondence between simulated and experimental results aids in the understanding of the quadrupole CID process. The high efficiency of the CID process in an RF-only quadrupole is significant in the development of a tandem quadrupole mass spectrometer for selected ion fragmentation studies.
134 citations
TL;DR: In this paper, an improved adiabatic calculation of the quadrupole moment of the H2 molecule and of its matrix elements between various vibrational rotational states is presented, with a reasonable estimate of the accuracy of transition elements between widely different vibrational states.
Abstract: We present an improved adiabatic calculation of the quadrupole moment of the H2 molecule and of its matrix elements between various vibrational rotational states. Particular attention is paid to making a reasonable estimate of the accuracy of transition elements between widely different vibrational states. An order of magnitude estimate of the nonadiabatic contribution to the quadrupole moment is also given and we show that it is typically of the order of a tenth of a percent of the adiabatic value.
130 citations
TL;DR: In this paper, a general simplification of the complex Mossbauer spectra often obtained in ferromagnets is presented, and the evaluation of the hyperfine field distribution and the effects of isomer and quadrupole shift distributions are discussed.
89 citations
TL;DR: In this paper, the low temperature specific heat of the hexagonal intermetallic compound UPd3 reveals a contribution from low lying crystal field levels, and sharp phase transitions are observed at temperatures of 6 and 7 K respectively.
80 citations
01 Jun 1978
TL;DR: In this article, the components of the electric quadrupole coupling tensor (eQq zz ), the electric dipole moment along the molecular axis (μ el ), the spin-rotation constant (c ⊥ ) and the molecular g -factor perpendicular to the molecularaxis ( g ⊩ ), and the anisotropy in the magnetic susceptibility ( x | − x ⊵ ) for the ground vibrational state of nitrous oxide (14 N 14 N 16 N 16 O) have been determined.
Abstract: The molecular beam electric resonance method has been used to obtain the components of the electric quadrupole coupling tensor ( eQq zz ), of the electric dipole moment along the molecular axis (μ el ), the spin—rotation constant ( c ⊥ ) and the molecular g -factor perpendicular to the molecular axis ( g ⊥ ), and the anisotropy in the magnetic susceptibility ( x | − x ⊥ ) for the ground vibrational state of nitrous oxide ( 14 N 14 N 16 O). The same quantities, except x | − x ⊥ , have also been determined for the (01 1 0) excited vibrational state. For this state the l -doubling constants q ν 2 and μ ν 2 , perpendicular anisotropy ( eQq xx − eQq yy ) in nuclear quadrupole tensor, the anisotropy ( c | — c ⊥ ) in the spin-rotation constant, and the molecular g -factor ( g | ) parallel to the molecular axis have been obtained.
75 citations
01 Sep 1978
TL;DR: In this article, the S 2p, S 2s and F 1s inner shell excitation spectra of SF 6 have been examined by small angle, inelastic scattering of 2.5 keV electrons.
Abstract: The S 2p, S 2s and F 1s inner shell excitation spectra of SF 6 have been examined by small angle, inelastic scattering of 2.5 keV electrons. While the main features of the spectra are in agreement with previous photoabsorption spectra, a number of new features have been observed. A detailed investigation of the S 2p spectrum below the ionization limit has been performed. The weak Rydberg structure in this region has been interpreted on the basis of a comparison of the present electron energy loss results with previous photoabsorption studies. Part of the Rydberg structure in the electron impact spectrum has been identified as arising from electric quadrupole transitions.
69 citations
TL;DR: In this paper, various properties of hydrogen fluoride are calculated as functions of internuclear separation using an MCSCF wave function, including dipole, quadrupole and octopole moments, diamagnetic contributions to the magnetizability and the nuclear magnetic shielding, the electric field gradients at the nuclei, the polarizability, and the A tensor.
Abstract: Various properties of hydrogen fluoride are calculated as functions of internuclear separation using an MCSCF wavefunction. The properties considered are the dipole, quadrupole and octopole moments, the diamagnetic contributions to the magnetizability and the nuclear magnetic shielding, the electric field gradients at the nuclei, the polarizability and the A tensor. Vibrational corrections to these properties have been included. Good agreement with the experimental results is found for the whole range of properties.
61 citations
TL;DR: In this paper, the ground states of the first-row atoms with estimated uncertainties of less than 3% were calculated from correlated wave functions for the ground-state of the atoms Li through Ne (in atomic units): 1428, 301.8, 145.7, 64.20, 30.72, 21.20 and 12.69.
Abstract: Static quadrupole and mixed dipole-octupole polarizabilities are calculated from correlated wave functions for the ground states of the first-row atoms with estimated uncertainties of less than 3%. The following mean quadrupole polarizabilities are obtained for the atoms Li through Ne (in atomic units): 1428; 301.8; 145.7; 64.20; 30.72; 21.20; 12.69; 7.726. Correlation contributions are found to range from -12% (Be) to +20% (O).
60 citations
TL;DR: In this article, the ground and excited vibrational states were measured using millimeter oscillators which were phase locked to harmonics of a Hewlett-Packard microwave spectrometer's X-band source.
56 citations
TL;DR: In this article, the theoretical values for weighted oscillator strengths for 2s22pn-2s2pn+1 and 2s2PN+1-2pn + 2pn+2 electric dipole transitions and for 2 s22pn magnetic dipole and electric quadrupole transitions are presented.
TL;DR: In this article, the interaction of a gravitational wave with an oscillating EM field inside a detector is analyzed in the frame in which the detector's walls are at rest, and the interaction is described in terms of a time-dependent dielectric tensor.
Abstract: The interaction of a gravitational wave with an oscillating EM field inside a detector is analysed in the frame in which the detector's walls are at rest. The interaction is described in terms of a time-dependent dielectric tensor and the energy transfer is derived from a generalised Poynting theorem. The energy transfer is maximum when the GW frequency matches one of the frequencies of quadrupole moment of the EM field. Provided the Q-value of the detector is sufficiently high this method seems particularly suitable for observing GWs emitted by periodic sources.
Abstract: A general variational method for calculating electronic multipole molecular polarizabilities is developed. Special emphasis is given to the pure dipole α, dipole-quadrupole A and pure quadrupole C terms. Applied to hydrogen fluoride, its results are comparable with those of a finite perturbations calculation but the A values are systematically too low. In the case of methane, one finds
TL;DR: In this paper, the burst of gravitational radiation emitted during the initial collapse and rebound of a homogeneous ellipsoid with internal pressure is analyzed numerically, and the total gravitational (quadrupole) radiation energy loss, the radiation spectra and the wave forms for several collapse sequences, parametrized by their initial deviations from spherical symmetry are calculated.
Abstract: The burst of gravitational radiation emitted during the initial collapse and rebound of a homogeneous ellipsoid with internal pressure is analyzed numerically. a configuration of mass 1.4 M/sub sun/ is assumed to collapse aspherically from rest at an initial density of 10/sup 1/0 g cm/sup -/3. The deviations from spherical symmetry arise from rotation and internal magnetic fields; deviations from axisymmetry are also considered. By following the collapse along two distinct low-entropy adiabats (''hot'' and ''cold'' collapse) on free-fall time scales, we estimate the maximum amount of gravitational radiation liberated during the initial implosion of a compact stellar core. We calculate the total gravitational (quadrupole) radiation energy loss, the radiation spectra, and the wave forms for several collapse sequences, parametrized by their initial deviations from spherical symmetry. A minimum estimate of the total neutrino losses during this initial collapse phase is also provided.
TL;DR: In this paper, a long path cell was used with a difference frequency laser system to study the electric quadrupole vibration-rotation spectrum of the deuterium molecule in the 2.8-3.9μm region.
Abstract: Frequency tunable infrared radiation from a difference frequency laser system has been used with a long path cell to study the electric quadrupole vibration–rotation spectrum of the deuterium molecule in the 2.8–3.9 μm region. A ratio method as well as frequency modulation were used to detect the weak absorption. Sub-Doppler linewidths due to collisional narrowing were observed with a D2 pressure of 1 atm. The wavelengths of 11 transitions were measured relative to infrared reference lines, and improved molecular constants for the ν = 0 and 1 states of D2 were determined.
TL;DR: In this article, the diamagnetic part of the magnetizability and nuclear shielding tensors, and electric field gradients in CO2, OCS and CS2 were analyzed.
Abstract: Ab initio calculations have been made of molecular quadrupole moments, the diamagnetic part of the magnetizability and nuclear shielding tensors, and electric field gradients in CO2, OCS and CS2. B...
TL;DR: In this paper, the cyclotron resonance of protons and electrons in a magnetic field of 5.7 Tesla produced by a superconducting solenoid has been measured.
Abstract: The cyclotron resonance of protons and electrons in a magnetic field of 5.7 Tesla produced by a superconducting solenoid has been measured. Protons and electrons were alternately confined in an electrostatic quadrupole trap. The quotient of the cyclotron frequencies provides a first direct determination of the proton-electron mass ratio. The result ofM p /M e =1836.1502(53) agrees with other more precise but indirect determinations of this quantity.
TL;DR: In this paper, the endor of the self-trapped exciton in KCl is studied using the optical detection technique, and the contact interaction with the neighbouring nuclei is very similar to that of the F centre in its ground state which indicates that the radial extent of electronic wavefunctions are similar in the two cases.
Abstract: ENDOR of the self-trapped exciton in KCl is studied using the optical detection technique. The contact interaction with the neighbouring nuclei is very similar to that of the F centre in its ground state which indicates that the radial extent of electronic wavefunctions are similar in the two cases. The quadrupole resonance of the two central halogen nuclei was also detected, observation of two different quadrupole splittings indicates that the self-trapped exciton is slightly displaced from the centrosymmetrical position between two lattice sites.
TL;DR: The amplitude of the gravitational wave from the Crab pulsar (PSR0531+21) is within 2 orders of magnitude of 10−27, but that the Vela pulsar is likely to produce waves of amplitude a factor 10 to 100 larger.
Abstract: PROGRESS in the development of ultra-high-Q dielectric crystals (Bagdasarov et al. unpublished data) has caused experimenters in the field of general relativity to look for rotation-induced gravitational radiation from pulsars (D. H. Douglass, unpublished data). If one could control the frequency of oscillation of a high-Q crystal, keeping it in phase with the electromagnetic signals observed from a pulsar, one might hope to absorb a measurable amount of (quadrupole) gravitational radiation at twice the pulsar frequency. Press and Thorne1 in 1972 estimated that the gravitational waves from the Crab pulsar would produce a dimensionless strain in a detector on Earth of h∼10−26 to 10−28, and that other pulsars would be several orders of magnitude fainter. Additional observational data, and progress in pulsar models during the past five years, make a new estimate desirable. I report here that the amplitude of the gravitational waves from the Crab pulsar (PSR0531+21) is likely to be within 2 orders of magnitude of 10−27, but that the Vela pulsar (PSR0833−45) is likely to produce waves of amplitude a factor 10 to 100 larger.
TL;DR: In this article, the deuteron quadrupole coupling frequencies in molecules computed from ab initio wavefunctions in a double-zeta basis were reported, which exceed observed coupling frequencies by 20%.
Abstract: Deuteron quadrupole coupling frequencies in molecules computed from ab initio wavefunctions in a ’’double‐zeta’’ basis are reported. They exceed observed coupling frequencies by 20%. Charge on the deuteron and atom to which it is bonded account for 98% of the electric field gradient.
TL;DR: In this article, the hyperfine structure of the low-lying atomic levels 4d2 5s23F2, 3, 4 and 4d3 5s has been studied using the atomic-beam magnetic-resonance method.
Abstract: The hyperfine structure of the low-lying atomic levels 4d2 5s23F2, 3, 4 and 4d3 5s5F2, 3, 4, 5 of91Zr has been studied using the atomic-beam magnetic-resonance method. Using intermediate coupling wave functions derived for the configurations (4d+5s)4 the experimental data are analysed with respect to the effective operator formalism. The effective radial parameters of the magnetic dipole and electric quadrupole interaction are determined for the two configurations 4d2 5s2 and 4d3 5s and are compared with relativistic calculations. The value obtained for the electric quadrupole moment of the91Zr nuclear ground state isQ=− 0.21(2) barn (uncorrected for core polarization effects).
TL;DR: In this article, a duoplasmatron is injected along the axis of a linear quadrupole and the lifetime is about 100 mu s; losses occur mainly at the ends, transverse losses being negligible.
Abstract: Plasma from a duoplasmatron is injected along the axis of a linear quadrupole. Peak number densities of about 5*109 cm-3 and temperatures of about 10 eV are achieved. The lifetime is about 100 mu s; losses occur mainly at the ends, transverse losses being negligible. This hot plasma is embedded in a cold plasma (0.5-1 eV) part of which drifts upstream towards the source. It is suggested that this arises from the action of a positive sheath at the far end of the device, maintained by an excess electron current from the source. Density and potential fluctuations are observed throughout the plasma but are large only in a zone bounded approximately by the critical surface and the surface of minimum field line length.
TL;DR: In this paper, the decay of the isoscalar giant quadrupole resonance in a 16 O (α,α'c) coincidence experiment at E α =155 MeV was studied.
TL;DR: In this article, the quadrupole coupling tensors were determined from the ground vibrational state of three isotopic species of COCl2 in microwave transitions with J values between 1 and 41.
Abstract: Microwave transitions between 24 and 154 GHz in the ground vibrational state of three isotopic species of COCl2 have been analysed. Rotational constants and quartic and sextic centrifugal distortion constants were obtained for transitions with J values between 1 and 41. From transitions with suitably large quadrupole splittings, the diagonal elements of the quadrupole coupling tensors were determined. The rotational data were analysed to give both r0 and rz structures, the r0-structure [r(C—Cl)= 174.01 (8) pm, r(C—O)= 117.94 (17) pm and ClCCl = 111.93 (8)°] being rather different from an earlier reported microwave structure. The quartic centrifugal distortion constants were shown to be consistent with a recently determined force field. The force fields of carbonyl and thiocarbonyl halides were compared.
TL;DR: Deuterium quadrupole coupling constants have been determined by distant endor spectroscopy for a series of carboxylic acids in which deuterium is substituted at the H-bond position.
Abstract: Deuterium quadrupole coupling constants have been determined by distant ENDOR spectroscopy for a series of carboxylic acids in which deuterium is substituted at the H-bond position. The measured coupling constants cover a range of 40 to 175 kHz corresponding to a variation of the bridge (O-H … O) length of 2·45 to 2·70 A. Features of the electronic and geometrical structure which principally determine e 2 qQ and η of deuterium in these H-bond situations have been assessed. To aid this assessment a simple model is proposed on which theoretical calculations of the INDO MO type are based. Good agreement between experiment and theory is obtained. It is concluded that for calculation of the electric-field gradient tensor two and three-centre integrals in the vicinity of the H-bond cannot be neglected, and further, in the cases of short and symmetrical H-bonds, e 2 qQ can change sign. Our studies also indicate that in non-ionic systems the asymmetry parameter η is primarily determined by the molecule itself, ra...
TL;DR: In this article, the (199Hg)+ ions were stored in an RF quadrupole electric field and their ground state hyperfine populations pumped optically using the ion resonance radiation at 1942 A from a (202Hg) isotope enriched lamp.
Abstract: The (199Hg)+ ions were stored in an RF quadrupole electric field and their ground state hyperfine populations pumped optically using the ion resonance radiation at 1942 A from a (202Hg) isotope enriched lamp. A microwave field at 40.5 GHz was phase-locked to the 1350th harmonic of the output of a frequency synthesizer, referenced to a Cs-beam frequency standard. Using a digital averager, a high background suppression optical system monitored the fluorescence light from the ions. Linewidths on the order of 3 Hz were observed for the “field-independent” 0-0 transition, and a value of 40, 507, 348, 051±50 Hz was deduced for the magnetic hyperfine interval, corrected to zero magnetic field.
TL;DR: In this paper, the parity-forbidden transitions 2P→2D and 2D→4S within the ground configuration (2p)3 of atomic nitrogen have been observed as phonon and vibron-induced emission bands in luminescence spectra of solid nitrogen and have been attributed to dipole radiation induced by dynamic crystal fields of odd parity with respect to the substitutionally trapped atom in the N2 lattice.
Abstract: The parity‐forbidden transitions 2P→2D and 2D→4S within the ground configuration (2p)3 of atomic nitrogen have been observed as phonon‐ and vibron‐induced emission bands in luminescence spectra of solid nitrogen and have been attributed to dipole radiation induced by dynamic crystal fields of odd parity with respect to the substitutionally trapped atom in the N2 lattice. We confirm this interpretation by an a priori calculation of the absolute transition probabilities and band shapes, using known atomic, molecular, and crystal properties of nitrogen and no adjustable parameters. The induced dipole moments are calculated from the vibrationally modulated quadrupole fields of the host molecules at the site of the polarizable guest atom. The dynamics of the doped lattice are treated by a normal‐coordinate analysis of the ’’supermolecule’’ consisting of the atom and its 18 nearest radially relaxed N2 neighbors suspended in the unperturbed surrounding N2 lattice. The calculated dipole‐weighted densities of phon...
TL;DR: In this paper, the double-spin-flip transitions were used to obtain nuclear quadrupole coupling tensors in EPR spectra of frozen solutions of copper/f-ketoenolates.
TL;DR: In this paper, a low-density plasma composed solely of massive atomic ions, namely Tl+ and I−, was produced by photodissociation of molecular TlI at low pressure, using the powerful 206 nm atomic iodine emission line, and confined in a Paul rf quadrupole electric field.
Abstract: A low-density plasma composed solely of massive atomic ions, namely Tl+ and I−, was produced by photodissociation of molecular TlI at low pressure, using the powerful 206 nm atomic iodine emission line, and confined in a Paul rf quadrupole electric field. A simple theoretical model based on an infinite homogeneous plasma of low density is used to estimate the perturbation of the ion oscillation frequencies in the external field due to the electrostatic interaction between the ions. The decay characteristics of the plasma under ionic recombinations were observed over a period of 10s, and the absolute ion density determined to be 1.1×107 cm−3 with a maximum energy on the order of 5 eV.
01 Jan 1978
TL;DR: In this paper, the electric field gradient at the octahedral sites in biotite is calculated by use of the point charge model for the ideal crystal structure, and the contribution from the overlap distortions of cation orbitals by the surrounding ligands is included.
Abstract: The electric field gradient at the octahedral sites in biotite is calculated by use of the point charge model for the ideal crystal structure. The contribution from the overlap distortions of cation orbitals by the surrounding ligands is included. The calculated values of the ferric quadrupole splittings are in good agreement with those obtained from Mossbauer spectra of micas. The effect of the neighbouring point defects and of real structure features of biotite on the electric field gradient are computed. It has been found that various point defects in adjacent sites produce varying values of ferric quadrupole splittings, which exceed the difference between the ideal parameters at the two distinct octahedral sites. A new interpretation of the biotite Mossbauer spectra is suggested.