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The beam optics in a nuclear microprobe is considered on the basis of quality criteria for focusing systems. In this consideration, empirical criteria with dominant chromatic or intrinsic spherical aberrations are used. In a more general criterion, where all aberrations can be taken into account, the maximum acceptance for a fixed beam spot size on the target is used. Another criterion, that is closest to an experiment, is based on the condition of the minimum spot size at a fixed beam current and takes into account the nonuniform distribution of ions in the phase volume. This review summarizes the studies of various types of quadrupole focusing systems and implies the need for further development of the nuclear microprobe by using aberration correctors and a compact system. The analysis of the influence of various aberrations on the resolution of a nuclear microprobe is conducted with special attention paid to the positioning aberrations in separated quadrupole probe-forming systems. It is demonstrated why integrated multiplets of quadrupole lenses are preferred in such systems. Methods to process experimental results for an adequate determination of the spot size on the target are considered.

In this study, we investigated the formation of acoustic fields and their influence on the particle distribution in complex-shaped acoustofluidic devices by considering the quadrupole hyperbolic resonator as a representative benchmark problem using an approach that can be applied to other resonator geometries. The Navier–Stokes equations for gases were solved twice, with different boundary conditions each time. An approach based on the limiting velocity method was used to simulate the formation of acoustic streaming and particle focusing. The effects of phase shifts in the boundary oscillations on the acoustic streaming and particle focusing patterns in the quadrupole hyperbolic resonator were investigated. The transient formation processes of Rayleigh vortices and the particle distributions were simulated at the resonant mode. Zones with drastically increased particle concentrations (acoustic traps) were identified. The results showed that the resonant frequency, locations of acoustic traps, and their form were highly dependent on the phase shifts of the boundary oscillations.

Pair approximation technique has been used to study the quadrupolar ordering properties for the 2D magnetic spin-1 Ising nanoparticles, consisting of core and surface parts with an interface coupling. Similar to the magnetic hysteresis, it has been shown that the quadrupole order parameter (Q) as a function of single-ion anisotropy (D) has a ‘hysteresis’ character which is generally called quadrupole (or QD) hysteresis. The observed QD loops strongly depend on temperature (T), external magnetic field (H) and biquadratic exchange interaction (K). Shifted QD loops with an asymmetry are found when H and K values are increased. These behaviors are also discussed in relation to other theoretical findings. © 2020 Akdeniz Üniversitesi One of the authors (RE) acknowledges the support from the Scientific Research Projects Coordination Unit of Akdeniz University. 2-s2.0-85103227901

The anisotropic infinitesimal coefficients of thermal expansion (CTE) and the peritectic transformation of orthorhombic-HfTiO4 (space group: pbcn, #60) to tetragonal-HfO2 (space group: P42/nmc, #137) plus liquid at 1980 °C (O-HfTiO4 ⇄ T -HfO2+L(Hf,Ti,O)) have been studied by in-situ X-ray powder diffraction from room temperature to complete melting (~2300 °C) in air, using a Quadrupole Lamp Furnace (QLF) and a Conical Nozzle Levitator (CNL) equipped with a 400 W CO2laser. Directions of zero thermal expansion were identified in the temperature range ~25 – 580 ˚C and visualized in 3D using distorted cones and 2D stereographic projections. The directions of zero thermal expansion change as a function of temperature. The (021) pole of orthorhombic HfTiO4 was identified as having the lowest root mean squared (rms) thermal expansion, ~12 times lower than the highest rms thermal expansion direction [100] over the temperature range: 25 – 580 ˚C. The topotactic, peritectic transformation has been fully described by extracting the lattice correspondence, lattice variant deformation and a structural motif (grouping of cations) that relates the two structures at the transformation temperature. Symmetry decomposition was performed to show that the orthorhombic-HfTiO4 and tetragonal-HfO2 structures are simply related by polyhedral rotations and cation oxygen coordination changes, in addition to a slight adjustment in cation positions.

In present work, the SST k-ω turbulence model and broadband noise source models are adopted to analyze the effect of the C groove on the energy performance and sources generated by dipoles and quadrupoles around a NACA0009 hydrofoil. Then the correlation mechanism between tip leakage flow (TLF) characteristics and its induced noise is investigated. Results show that the C groove significantly reduces both the area of the primary tip leakage vortex (PTLV) and the turbulent kinetic energy. It can be deduced that the closer the C groove is to the leading edge, the smaller the area of high decibel value of the dipole noise on the surface near the leading edge, but the area of the high decibel value of the dipole noise emitted from the blade tip becomes larger. Furthermore, compared with the original hydrofoil, the C groove reduces the area of quadrupole noise with maximum decrease of 29% for 50 dB. The turbulent kinetic energy in the flow region has a great influence on the quadrupole noise.

Quadrupole based mass spectrometry based detection has experienced enormous improvements in terms of sensitivity over the last centuries. This development has not been equally matched with improvements in selectivity. Hence, the use of unit mass based MS/MS transitions or high resolution (HRMS) based extracted ion chromatograms is gradually becoming insufficient in the field of high sensitivity multi-residue analysis (e.g. pesticides in food). As a consequence, commercial instruments hyphenating ion mobility (IMS) with low or high resolution mass spectrometry based detection have appeared. The use of such an additional (frequently claimed to be orthogonal) dimension is intended to increase selectivity. In addition, IMS derived collision cross section (CCS) has been proposed to be used as an additional identification point for the unambiguous identification of trace compounds in complex matrices. It is the topic of this paper to investigate the benefit of using such a hyphenated technique for trace analysis of small molecules in complex matrices. The potential of CCS to serve as additional identification point has been critically evaluated. Discussed are the effect of CCS data on false detects and missing detects of analytes present at trace levels. This involves the investigation of the physical resolving power provided by HRMS, IMS and chromatography as well as the correlation among these parameters (orthogonality). It is the conclusion that currently commercially available travelling wave and linear drift tube based IMS devices with a resolving power of up to 50 permit a reduction of false detects, yet this comes at the price of a higher likelihood of missing detects. The reduction of missing detects and the use of CCS as potential confirmatory information would require IMS resolving powers above 100.

The Optimized Energy Degrading Optics (OEDO) beamline was constructed at RIBF to produce slowed-down, well-focused radioactive-isotope beams at 10–50 MeV/u, and began operation in June 2017. We examined the performance of the OEDO system by decelerating high-energy medium-mass radioactive ions. The main components of the OEDO beamline are two superconducting quadrupole triplet magnets and one radio-frequency deflector. This paper introduces the unique design of the ion optics of the beamline and describes the achieved performance of the beamline in the commissioning and following physics experiments. We will discuss the properties of energy-degraded beams produced by the OEDO beamline by comparison of simulations and the achieved performance.

© 2019 Elsevier B.V. Radio-frequency (RF) ion guides, also known as Linear Paul Traps, are powerful devices to efficiently transport ion beams from high to low pressure regions while keeping good ion optical properties. A set of ion guides comprising three different RF quadrupole (RFQ) structures has been designed using ion-trajectory simulations to improve the performance of the In-Gas Laser Ionizations and Spectroscopy (IGLIS) technique currently under development at KU Leuven. Results of the commissioning tests for the total transport efficiency and transient time through the ion guides as well as the longitudinal energy spread and transverse emittance are found to be in agreement with ion trajectory simulations considering a realistic ion-atom interaction potential. ispartof: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms vol:463 pages:148-153 ispartof: location:SWITZERLAND, CERN, Geneva status: published

Astigmatism is a type of aberration in beam optics which causes asymmetry in transverse coordinates. This asymmetric beam often shows an elliptical profile instead of circular, which may cause differences between the major and minor ellipse axes diameters and ellipse azimuth angle. In this research work, a novel astigmatism correction system is proposed for electron accelerators with a minimum number of electromagnetic lenses. An adaptive quadrupole lens is designed by coaxially locating two quadrupoles 45 degrees apart from each other. The focusing and defocusing axes and the azimuth angle of the resultant adaptive quadrupole are determined adaptively by the vector sum of created magnetic fields of two coaxially located quadrupoles. The adaptive quadrupole lens is placed on the common focal point of two solenoids as part of an expander lens. In this way, the focal points of the major and minor axes of an elliptical beam are slightly changed from the common focal point of the expander. This act helps to increase the minor axis diameter of the electron beam while decreasing the major one, resulting in a circular profile. Both a 2D beam trajectory model in MATLAB and a 3D Particle Accelerator simulation with Computer Simulation Technology (CST) tool show that the proposed method successfully corrects the astigmatism having any elliptical parameters for a sample electron beam.

The anisotropic electrostatic parameters of truncated multipole expansion (atomic dipole and quadrupole) obtained for a series of nitrogen and phosphorus containing compounds allow for a reasonable physical interpretation and appear to be predictable in response to chemical substituent variation. These findings will be useful for prediction of anisotropic parameters in next generation force fields without the need to resort to quantum chemical calculations.

A multi-reflection time-of-flight mass spectrometer (MR-TOF) will be a critical component for quickly removing radioactive contaminants produced at the future “N = 126 factory” addition to ATLAS at Argonne National Laboratory (ANL). This unique thermalized ion beam facility will employ multi-nucleon transfer reactions to produce very neutron-rich isotopes relevant to the astrophysical r-process. Ion beams produced at this facility will include isobaric contaminants, while precision measurements of such rare isotopes typically require highly purified samples. Hence, to tackle this issue an MR-TOF has been built and commissioned at the University of Notre Dame in an off-line test setup comprising a thermionic source and a Bradbury-Nielsen gate (BNG) to create the ions bunches to be purified. Resolving power above 30,000, with a corresponding efficiency of 35%, has been achieved. Most of the ion beam losses could be the result of the large radial divergence of ion bunches produced by the BNG, hence greater efficiency and resolving power are expected once the MR-TOF is connected to an radiofrequency quadrupole (RFQ) cooler and buncher at ANL.

A radio-frequency quadrupole linear accelerator (RFQ) was developed and tuned for the heavy ion accelerator facility at Rare Isotope Science Project (RISP). The RISP RFQ has an 81.25 MHz operational frequency and a four-vane structure for a continuous-wave mode operation despite the fabrication difficulties of the huge cavity generated due to the brazing technology. The cavity is inherently insensitive to perturbations due to low frequency and a short cavity length. The linearly increasing profile of inter-vane voltage was tuned for all quadrants through not only movable slug tuners but also modification of the end-plate. In this study, a low-frequency RFQ with a novel, ramped field profile was tuned and the commissioning tests were conducted with a new tuning method compatible with the modification of the end-region geometry.

Molecular beams injected into the ISOLDE Radio-Frequency Quadrupole cooler and buncher (RFQcb), ISCOOL, have been studied under varying conditions using a new Time-of-Flight (ToF) detector. When a beam of molecules is injected into the RFQcb and interacts with the buffer gas, collisional dissociation processes may occur. In this study, two different beams of molecules, CO+ and N 2 + , were separately injected into ISCOOL, and two different buffer gases (pure helium or a 90:10 mixture of helium and neon) were used. The radio-frequency of the RFQcb was varied as the molecules, along with the fragments from the dissociation processes, were extracted from ISCOOL and studied using the new Time-of-Flight detector. The main finding of this work is that the rates for molecular dissociation within ISCOOL were very small for both CO+ and N 2 + , with the largest rates found for CO+.

A radioactive isotope (RI) separator named ERIS (electron-beam-driven RI separator for SCRIT) was constructed at the SCRIT (Self-Confining Radioactive isotope Ion Target) electron scattering facility at RIKEN RI Beam Factory and has been in operation since 2013. Recently, ion stacking and pulse extraction were developed at ERIS to improve the dc-to-pulse conversion efficiency of a radio-frequency quadrupole cooler buncher. Using a surface-ionization ion source, long-time stacking inside ERIS was realized and a dc-to-pulse conversion efficiency of more than 50% was achieved with a relatively small amount of buffer gas.

The microwave rotational spectrum of the aromatic 2,3-difluorophenol (2,3-DFP) has been recorded and analyzed in the frequency range of 5–25 GHz using a pulsed-jet Fourier transform microwave spectrometer. Rotational transitions were measured for the parent, the 18O, and all six 13C singly substituted isotopologues in natural abundance as well as the deuterium enriched 2HO-species. In addition to the rotational and quartic centrifugal distortion parameters, the quadrupole coupling constants of the deuterium species were determined. The rotational constants for the parent species are obtained as A = 2313.37516(14) MHz, B = 1797.935693(62) MHz, C = 1011.695171(36) MHz. For the deuterated species, the 2H quadrupole coupling constants are χaa = −0.11693(80) MHz and (χbb−χcc) = 0.4112(14) MHz. The partial rs substitution structure as well as a semi-experimental r0 structure was determined from the rotational constants of the observed isotopologues. Both rs and r0 structures agree well with each other and with MP2/6-311++g(2d, 2p) and B3LYP/6-311++g(2d, 2p) predicted equilibrium structures with the biggest deviation in heavy atom bond lengths being 0.008 A.

In this work, we report numerical research concerning a planar electromagnetically induced transparency (EIT) terahertz metamaterial capable of exhibiting refractive index sensing with high sensitivity. The unit cell of the proposed EIT metamaterial is consisted by metal cut wires with staggered H-shaped arrangement, and can display a sharply narrow transmission transparency peak at 2.653 THz with high quality-factor (Q-factor) valued 48.3. Through analysis of the extracted surface current distributions on metallic structures, it is confirmed that the EIT-like resonance results from the destructive interference of the electric quadrupole excited by the strong radiation of electric dipole. Furthermore, the EIT-like effect shows highly sensitive response to the refractive index of the covered layer. When it covered by 3 μ m -thickness analyte layer, the EIT metamaterial can yield a sensitivity of 0.2695 THz/refractive index unit (RIU) and a figure of merit (FOM) of 5.39. Meanwhile, it is also found that the sensitivity S is inversely proportional to the dielectric constant of the substrate material, and effective sensing capability maintains when the coverage thickness within 15 μ m . The proposed EIT metamaterial design provides great potential application for refractive index sensing performance.

The electric quadrupole response in 112,114Sn isotopes is investigated by energy-density functional (EDF) and three-phonon quasiparticle-phonon model (QPM) theory with special emphasis on electric quadrupole excitations located above the first collective 2 + state and below 5 MeV. Additional quadrupole strength clustering as a sequence of states similar to the recently observed pygmy quadrupole resonance in 124Sn is found. The spectral distributions and transition densities of these 2 + states show special features being compatible with oscillations of a neutron skin against the isospin-symmetric nuclear core. Furthermore, two (p, p ′ γ ) Doppler-shift attenuation (DSA) coincidence experiments were performed at the SONIC@HORUS setup. 2 + states with excitation energies up to 4.2 MeV were populated in 112,114Sn. Lifetimes and branching ratios were measured allowing for the determination of E2 transition strengths to the ground state. A stringent comparison of the new data to EDF+QPM theory in 112Sn and 114Sn isotopes hints at the occurrence of a low-energy quadrupole mode of unique character which could be interpreted as pygmy quadrupole resonance.

The fission mass distribution of Z=104-120 superheavy nuclei formed in 238U-induced reactions is investigated using the dynamical cluster decay approach. The cross-section for the formation of symmetric fragments with masses A 2 ± 20 of 274Hs⁎, 286Cn⁎, 286Fl⁎, and 302120⁎ nuclei are calculated over a wide energy spectrum by rationalizing the neck-length parameter (ΔR). The calculations are carried out by including the quadrupole ( β 2 i )-deformation of the fragments using hot and cold optimum orientation approaches. Within hot orientation criteria, symmetric fission distribution is observed for 274Hs⁎ nucleus which becomes highly asymmetric in nature for 302120⁎ compound system. The lead (Pb)-peaks originating due to quasi-fission process start competing while going from 274Hs⁎ to 302120⁎ nucleus. Additionally, the role of cold orientation approach is also explored for these nuclei which show the opposite trend in the mass distribution while going from Z=108 to Z=120 superheavy system. Further, the fission and asymmetric quasi-fission cross-sections are predicted for various entrance channels i.e. 58Fe+244Pu, 54Cr+248Cm, and 50Ti+249Cf and compared with experimentally available data of 64Ni+238U reaction to identify the favorable projectile-target combination for the synthesis of Z=120 nucleus. The results show that because of larger fusion probability, 50Ti+249Cf reaction seems to provide a favorable option for the synthesis of Z=120 superheavy nucleus.

The new Sumy nuclear microprobe for high resolution applications has the same beam line with the present microprobe and uses the same object and aperture collimators. The new probe-forming system is based on five magnetic quadrupole lenses of integrated design with four independent power supplies. It consists of quadrupole doublet of the present microprobe and quadrupole triplet which is allocated after the target chamber of the present microprobe. The electrostatic scanning system of a dog-leg type is located before the triplet. The new target chamber of rectangular design has an optical microscope, secondary electron detector, charged particle detector, target stage and possibility to equip additional devices. Such configuration allows one to install two microprobes for different applications at one beam line, that significantly reduces the cost of the new facility. The present paper describes the status of the new Sumy microprobe, its beam optics and design.

The cross over of β-, and γ-band at N = 94 in 158Gd signifies a major change in the nuclear structure of Gd isotopes. Using the microscopic dynamic pairing plus quadrupole (DPPQ) model, we reproduce this transition. The spectral features of the K π = 0 3 + , 2 1 + and 4 1 + bands besides the lower three: ground, β- and γ-bands have been analyzed. The B(E2) values from the K π = 0 2 + and K π = 0 3 + bands are analyzed to interpret the nature of these two bands. The K π = 0 2 + band is confirmed as the axially symmetric β-vibration. The K π = 0 3 + band is shown to be collective vibration, but instead of 2β vibration, it indicates very special features with large anharmonicity. The five excited 0 + states below 2.0 MeV identified in 158Gd from ( p , t ) reaction work are also predicted from the DPPQ model. The relative variation of β- and γ-band head energies and of K π = 0 3 + bands, and of K π = 4 + band with neutron number N in 152 - 160 Gd isotopes is reproduced. But the vibrational energy scale of the excited bands remains expanded. The algebraic interacting sd-boson model is also applied for evaluating the energy spectrum and the B(E2) ratios in these K-bands and for prediction of the multi-phonon 0 + states.

In this work, the effects of using collision/reaction cell (CRC) technology in quadrupole-based ICP-MS (ICP-QMS) instrumentation operated in single-particle (SP) mode have been assessed. The influence of (i) various CRC gases, (ii) gas flow rates, (iii) nanoparticle (NP) sizes and (iv) NP types was evaluated using Ag, Au and Pt NPs with both a traditional ICP-QMS instrument and a tandem ICP-mass spectrometer. It has been shown that using CRC technology brings about a significant increase in the NP signal peak width (from 0.5 up to 6 ms). This effect is more prominent for a heavier gas (e.g., NH3) than for a lighter one (e.g., H2 or He). At a higher gas flow rate and/or for larger particle sizes >100 nm), the NP signal duration was prolonged to a larger extent. This effect of using CRC technology has been further demonstrated by characterizing custom-made 50 and 200 nm Fe3O4 NPs (originally strongly affected by the occurrence of spectral overlap) using different CRC approaches (H2 on-mass and NH3 mass-shift). The use of NH3 (monitoring of Fe as the Fe(NH3)2+ reaction product ion at m/z = 90 amu) induces a significant peak broadening compared to that observed when using H2 (6.10 ± 1.60 vs. 0.94 ± 0.49 ms). This extension of transit time can most likely be attributed to the collisions/interactions of the ion cloud generated by a single NP event with the CRC gas and it even precludes 50 nm Fe3O4 NPs to be detected when using the NH3 mass-shift approach. Based on these results, the influence of a longer peak width on the accuracy of SP-ICP-MS measurement data (NP size, particle number density and mass concentration) must be taken into account when using CRC technology as a means to overcome spectral overlap. To mitigate the potential detrimental effect of using CRC technology in the characterization of NPs via SP-ICP-MS(/MS), the use of light gases and low gas flow rates is recommended.

Electron Cyclotron Resonance (ECR) ion sources and the production of multiple-charge positive ions with high efficiency in combination with a heavy-ion accelerator have opened the way to an alternative and complementary version of accelerator mass spectrometry (AMS). A notable strength of positive-ion over traditional AMS is the capability of ultra-high sensitivity detection of radioactive isotopes of noble gases, in particular 37Ar (t1/2 = 35 d) and 39Ar (269 y). The complete dissociation of molecular ions in the ECR and in particular of hydride ions of neighboring stable isotopes results in superior isotopic separation. However, the use of high charge states, necessary for acceleration to high energy, entails the existence of severe transmission degeneracies with stable ions having nearly equal mass-to-charge ratios, in addition to that of stable isobaric ions. Separation or discrimination of these parasitic ions require powerful and sophisticated dispersive systems at detection stage. We review here work performed and in progress at the ATLAS facility of Argonne National Laboratory (ANL) where an ECR ion source, a Radio-Frequency Quadrupole (RFQ), a superconducting linear accelerator and a Gas-Filled Magnet (GFM) are used as an AMS setup.

Collisional damping quadrupole ion guides have become popular tools in mass spectrometry. In such devices, ions are cooled by collisions with a buffer gas and focused to trajectories near the axis of the ion guide under the influence of a radio frequency (RF) field. This produces a narrow beam of low-energy ions which can be transported with high efficiency. Typically, quadrupole ion guides are constructed of four parallel rods to which RF voltages are applied. To overcome the dampening of the axial velocity component resulting from collisions with neutral gas particles, an additional static axial field is provided by dividing the rods in several segments and applying an electric potential to each segment. However, this method is mechanically complex, requiring a precise alignment of all segments, and several separate connections for the DC und RF voltages to all segments. In this work, we present a simple and low-cost segmented quadrupole ion guide design that is based on standard printed circuit boards (PCB) including both the segmented electrodes as well as the signal distribution network. Furthermore, we present simulations of the ion movement inside this PCB quadrupole and experimentally evaluate the ion transfer. Our measurements show that the segmented PCB quadrupole with planar electrodes reaches similar ion transmissions in comparison with conventional quadrupole ion guides built from segmented circular rods.

Experimental measurements of high resolution emission spectra of neutral atomic iodine (I I) have been extended to cover the mid-infrared spectral regions (1800–6000 cm−1) using Fourier transform spectroscopy. A total of 354 spectral lines are reported here in the above spectral range. While the region between 3000 and 6000 cm−1 were recorded using a conventional quartz Electrodeless Discharge lamps (EDL), spectra in the region 1800–3000 cm−1 were detected using specially prepared EDLs with a CaF2 window. Hyperfine structure analysis has been carried out on 224 spectral lines, of which 176 are reported for the first time. The magnetic dipole constant (A) and electric quadrupole constant (B) have been derived for 97 energy levels.

To demonstrate the selectivity of 14N nuclear quadrupole resonance (14N NQR) spectroscopy in chemistry and pharmacy, a study of sulfanilamide polymorphism was undertaken. We studied 3 known polymorphs of sulfanilamide by 14N NQR. We found at room temperature 2 sets of 3 14N NQR transition frequencies, corresponding to 2 different nitrogen sites in the crystal structure for each of 3 polymorphs. We measured the temperature dependence of all quadrupole frequencies ν+, ν-. In each set, only 1 of the 3 14N NQR frequencies is enough to characterize the polymorph. Spin-lattice relaxation time (T1) measurement is supplemental information. We also measured the transition temperature between polymorphs and estimated the ratio of polymorphs after thermal treatment of sample.

In optics, mode conversion is an elegant way to switch between Hermite Gaussian and Laguerre Gaussian beam profiles and thereby impart orbital angular momentum onto the beam and to create vortices. In optics such vortex beams can be produced in a setup consisting of two identical cylinder lenses. In electron optics, quadrupole lenses can be used for the same purpose. Here we investigate generalized asymmetric designs of a quadrupole mode converter that may be realized within the constraints of existing electron microscopes and can steer the development of dedicated vortex generators for high brilliance electron vortex probes of atomic scale.

Based on relativistic wavefunctions from multi-configurational Dirac–Fock method, a comprehensive theoretical study of atomic characteristics of energy levels, wavelengths, lifetimes, electric dipole, electric quadrupole, magnetic dipole, and magnetic quadrupole radiative rates is performed for the lowest 98 levels of the 2s2, 2p2, 2s3s, 2s3d, 2p3p, 2s4s, 2s4d, 2p4p, 2p4f, 2s2p, 2s3p, 2p3s, 2p3d, 2s4p, 2s4f, 2p4s, and 2p4d configurations of Ge XXIX and Kr XXXIII. The correlations within the n=9 complex, n being the principal quantum number of the outermost electron are accounted for in a systematic way and the Breit interactions and quantum electrodynamics effects are estimated. Similar data are also determined using the many-body perturbation theory. The accuracy of our results is determined through extensive comparisons with the available data from the Atomic Spectra Database of the National Institute of Standards and Technology and with published theoretical values. Our computed wavelengths are almost of spectroscopic accuracy, aiding line identification in extreme ultraviolet (EUV) and soft X-ray (SXR) spectra. The present complete set of data are very useful for modeling and diagnosing fusion plasmas.

The 101–000 and 202–101 rotational transitions of a monohalomethylene, HCI, are observed in a discharge plasma of diiodomethane by Fourier-transform microwave (FTMW) and FTMW-microwave double-resonance spectroscopy. The effective rotational constant ( B + C ) / 2 , the centrifugal distortion constant Δ J , and the quadrupole coupling constant of the iodine nucleus are determined from the observed line frequencies. The nuclear spin-rotation coupling constant C bb is required to be included into the set of fitting parameters for a satisfactory analysis of the observed line frequencies.

Bond breaking related with plastic deformation in a deformed metallic glass Zr50Cu50 is investigated by molecular dynamics simulations. The results show that the spatial distributions of broken bonds are closely correlated with local shear strains, and the clustering behaviors of atoms with broken bonds (flow defects) are characterized with different stages of plastic deformation. The average distance among those clusters of flow defects decreases as the strains increase, which follows the curvature quadrupole model for flow defects in ideal amorphous solids. For the first time, the features of bond breaking processes are quantitatively measured with the chemical composition, bond length and orientation, bond pairs, local five-fold symmetry and quasi-nearest atoms, whose threshold values are important factors that could characterize the flow defects in metallic glasses under plastic deformation. The shape, orientation and energetics of flow defects quantitatively characterized by the bond breaking analysis thus facilitate our understanding on the deformation mechanisms in metallic glasses.

We investigate the stability and self-consistency of the SU(3) symmetry and quadrupole deformation in light nuclei in terms of the Nilsson model and quasi-dynamical symmetry. It turns out that SU(3) is a remarkably good symmetry for commensurable major axes, similarly to the finding of the simple harmonic oscillator interaction. The method serves as an alternative to the well-known energy-minimum calculation for the determination of the shape isomers. In case of the 16O, 20Ne, and 24Mg nuclei the results of the two different procedures are in good agreement with each other. Keywords: Quasi-dynamical SU(3) symmetry, Quadrupole deformation, Nilsson-model, Shape isomers

A millimeter-wave intracavity OROTRON spectrometer in combination with a pulsed supersonic pin-hole jet expansion has been used to record a new subband of the CO–N 2 weakly bound van der Waals complex in the 100–150 GHz region. Seven lines were assigned to the K = 0–0, ( j CO , j N2 ) = (2, 0)–(1, 0) “hot band” transitions to a thus far unobserved K = 0 state at 9.336 cm −1 above the ground state. This is the highest in energy van der Waals mode detected so far, and this mode may be interpreted as a doubly excited bending vibration of the CO– ortho N 2 nuclear spin isomer. Hyperfine structure caused by two 14 N nuclei was partly resolved for the measured lines, and the quadrupole coupling constant, associated with the N 2 subunit, together with rotational and centrifugal distortion parameters were precisely determined for the new K = 0, ( j CO , j N2 ) = (2, 0) state. The high lying energy levels of this state provided a sensitive test for the recent ab initio potential energy surfaces.

Some halogen bonded complexes of N-iodosuccinimide (NIS) with the nitrogen atoms at the donor and acceptor positions have been investigated by 14N nuclear quadrupole resonance (NQR) spectroscopy. The data are analyzed in view of the change of the principal values of the quadrupole coupling tensor produced by halogen bonding. The results show that the deformation of the nitrogen electron orbitals is in the presently studied halogen bonded systems comparable to the one observed in strong hydrogen bonded systems. The order in which the strength of the halogen bond acceptor increases is determined. A possible iodine displacement to a position, which is closer to the acceptor nitrogen atom than to the donor nitrogen atom may occur in the complex NIS-(3-picoline). In all studied complexes the deformation of the nitrogen electron orbitals caused by the halogen bond decreases with increasing temperature at both the donor and acceptor nitrogen positions.

In this study, a method of simultaneous dual mass detection for single cell analysis by quadrupole-based ICP-MS (ICP-QMS) is proposed. The method shows potential for use in quantitative investigations of nanoparticle association and elemental composition of cells. Dual mass detection had been attempted in the analysis of two-element core-shell nanoparticles and in isotope dilution analysis. In this method the detector switches between two selected masses during the analysis. Dual mass mode eliminates the discrepancies in signal that can occur due to sample instability or fluctuation in sample uptake when two masses are analysed sequentially by conventional single cell analysis (SP mode). Preliminary tests showed that using an Mg spike as marker of cells in dual mass mode was feasible for the quantification of cells. The method showed good linearity and a reproducible detection rate, and the results were comparable to the SP mode. The approach was then employed with algal cells exposed to silver nanoparticles (AgNP), to study on the Ag-associated cells and AgNP by monitoring the Ag and Mg signal in one analytical run. Finally, Mg and Mn were detected, and then quantified using the same approach to evaluate the elemental composition and correlation between different elements of the exposed cells. It is believed that this dual mass approach can extend the capability of ICP-QMS for multi-elemental detection at the single cell level, representing an enormous potential for size characterization, quantification and elemental composition evaluation in single cell (particle) analysis.

In Harbin, the 300 MeV proton microprobe system with long-length quadrupole lenses, as a component of the Space Environment Simulation Research Infrastructure (SESRI), is under development driven by many applications in space science and proton therapy. Significant challenges have previously been addressed including minimization of ion scattering from collimators and the development of promising focusing systems compatible with the large beam magnetic rigidity. Here the intrinsic aberrations contributed by the fringe field regions of quadrupole lenses in the probe forming lens system are investigated with respect to the model used for the fringe field profile. The investigation compares the rectangular model, commonly used with the matrix method, and a more sophisticated model employing a multiphysics code for the full field profile used with a numerical raytracing method. For computational and constructional efficiency the proposed triplet system of long-length quadruple lenses required to achieve strong focusing was split into three pairs of two identical short quadrupole lenses, forming a sextuplet microprobe system. The comparison of the two fringe field models show large variations in the aberration coefficients of this system, however the rectangular model is suitable for a broad survey of possible systems to identify promising configurations for further optimization.

This paper provides the physical design of a low-energy proton irradiation facility for space radiation effect research, based on an existing linear accelerator (linac)-based compact neutron source . The beam requirement of the low-energy proton irradiation consists of a proton flux range of 1 0 8 – 1 0 9 p ∕ cm 2 ∕ s with a nonuniformity of less than 10% in the target diameter area of 2 cm, and optional proton energies of 1 MeV to 13 MeV. Based on the existing high-current proton linac, the flux range and nonuniformity of the proton beam at the target can be achieved by inserting beam apertures, adjusting quadrupole fields to expand the beam size, and decreasing the repetition rate of the beam pulse. To measure the energy distribution of the protons, one CdZnTe detector can be employed. The above approach is performed on the physical design of the low-energy proton facility for the Compact Pulsed Hadron Source at Tsinghua University. The proton flux at the target can be reduced from 6 . 2 × 1 0 14 p ∕ cm 2 ∕ s to 1 . 2 × 1 0 8 − 3 . 0 × 1 0 9 p ∕ cm 2 ∕ s , and proton energies of 0.56, 5.0, 8.2, and 10.5 MeV can be obtained separately with the energy degrader (aluminum) thicknesses of 75, 800, 550, and 300 μ m. Irradiation nonuniformity is less than 10%. Energy spread is less than 10% for the proton energy of 3.0, 5.0, 8.2, and 10.5 MeV, except for the low energy of 0.56 MeV.

Nearly-free internal rotation produces huge (>1 GHz) tunneling splittings in the rotational spectrum of meta-chlorotoluene. Additionally, the simultaneous presence of two chlorine (35Cl and 37Cl) isotopologues results in dense spectra with complicated hyperfine patterns, hampering the spectral analysis by conventional spectroscopic techniques. Sub-Doppler molecular-beam Fourier transform microwave rotational spectroscopy has been used to study the internal rotation and nuclear quadrupole coupling terms in meta-chlorotoluene. Notably, with the halogen substituent in meta position of the methyl internal rotor, the periodic torsional potential contains six-fold V6 terms that are larger than the three-fold V3 terms. Molecular parameters for the two isotopologues of meta-chlorotoluene are reported and compared with DFT (B3LYP) and ab initio (MP2) calculations.

The thermal stability of bimodal Ta-Hf nanometallic multilayers, comprised of columnar and brick-like grains, was explored by characterizing films annealed at 550 °C and 1000 °C. Although the brick-like grains recrystallized, their grain size remained in the nanoscale. Recrystallization of the columnar grains was hindered by semi-coherent sub-grain boundaries and quadrupole points. Growth of the recrystallized brick-like grains was prevented by Hf precipitates, which activated kinetic and thermodynamic stabilization mechanisms. The present results outline a promising route to improve the stability of nanomaterials by using bimodal nanometallic multilayers with engineered interfaces while expanding the available architectures to synthesize nanocrystalline materials.

In this paper we demonstrate that generation of the solitary density wave in the strongly coupled one component Coulomb system of particles confined in a long quadrupole electrodynamic Paul trap is possible, when the energy losses due to air viscosity can be compensated by the energy contribution of the altering electric fields of the trap. Results of this paper allow to identify observed solitary waves as the caustics (according to definition of the book “Catastrophe Theory” by V. I. Arnold) and can be considered as the new experimental support of the general versatility of the caustic theory in describing different physical phenomena not only in collisionless systems of particles but also when interparticle interaction and interaction with external fields in viscous media are strong.

A new method of measuring the integrated gradient of quadrupoles using a Hall probe is described. The proposed method is developed to measure a Halbach-type permanent magnet quadrupole (PMQ), whose roll angle is difficult to determine for alignment in the measurement. In the proposed method, we establish a roll angle alignment for the magnet, Hall probe, and motor stage based on the field distribution. The proposed method is analyzed and experimentally verified, and a setup is built. Measurement results have confirmed its feasibility for measuring the integrated gradient of PMQs with favorable reproducibility. This method is also an optional method for measuring the integrated gradient of electromagnets.

The ground-state shape (phase) evolution in Er and Yb isotopes is manifested in the axially deformed Nilsson mean-field plus extended pairing model. The energy ratio R 0 2 + / 2 1 + , the odd-even mass differences, the ground-state occupation probabilities of valence nucleon pairs with different angular momenta and the information entropy are calculated. It is shown from these quantities as functions of the quadrupole deformation parameter and the overall pairing interaction strength that the ground-state shape (phase) evolution is mainly driven by the pairing interaction and less affected by the quadrupole deformation, which thus provides a possible origin of the ground-state shape (phase) evolution of these isotopes.

Cluster ion beam effect on large biomolecules is interesting due to differences in ion beam characters from normal ion beams and applications in analysis of the molecules as the cluster ion beam should be more effective in fragmenting large and complicated biomolecules to make study of the complex molecular structure possible. Argon gas cluster ion beam (Ar-GCIB) at 10 keV bombarded samples of DSPC (1,2-distearoyl-sn-glycero-3-phosphocholine, C44H88NO8P, monoisotopic molecular weight 789.6 Da), angiotensin II (C50H71N13O12, monoisotopic molecular weight 1045.5 Da) and leucine enkephalin (C28H37N5O7, monoisotopic molecular weight 555.6 Da). The bombardment-generated fragments were in-situ analyzed and measured using the tandem quadrupole – time-of-flight secondary ion mass spectrometry (Q-ToF-SIMS) technique. The experiment was operated within an integrated system of Ar-GCIB and Q-ToF-SIMS. Two modes, i.e. MS (quadruple off) and MS/MS (quadrupole on), were applied in the ToF-SIMS measurement. Particularly, the secondary ion fragmentation with the collision energy dependence was focused in the study.

It has previously been shown that ${}^{14}$N NMR spectra can be reliably obtained through indirect detection via HMQC experiments. This method exploits the transfer of coherence between single- (SQ) or double-quantum (DQ) ${}^{14}$N coherences, and SQ coherences of a suitable spin-1/2 'spy' nucleus, e.g., ${}^1$H. It must be noted that SQ-SQ methods require a carefully optimized setup to minimize the broadening related to the first-order quadrupole interaction (i.e., an extremely well-adjusted magic angle and a highly stable spinning speed), whereas DQ-SQ ones do not. In this work, the efficiencies of four ${}^{14}$N excitation schemes (DANTE, XiX, Hard Pulse (HP), and Selective Long Pulse (SLP)) are compared using J-HMQC based numerical simulations and either SQ-SQ or DQ-SQ ${}^1$H-{${}^{14}$N} D-HMQC experiments on L-histidine HCl and N-acetyl-L-valine at 18.8 T and 62.5 kHz MAS. The results demonstrate that both DANTE and SLP provide a more efficient 14N excitation profile than XiX and HP. Furthermore, it is shown that the SLP scheme: (i) is efficient over a large range of quadrupole interaction, (ii) is highly robust to offset and rf-pulse length and amplitude, and (iii) is very simple to set up. These factors make SLP ideally suited to widespread, non-specialist use in solid-state NMR analyses of nitrogen-containing materials.

Synchrotron radiation induced carbon contaminations on optical elements is widely considered to be a major concern for a beamline. The purpose of this paper is to study on glow discharge cleaning (GDC) of the mirror box, striving to prevent carbon contamination formation fundamentally by obtaining a cleaner vacuum chamber. In order to theoretically understand GDC, a 2D fluid model of Ar/O2 discharge was established, and the discharge physical parameters were obtained under different conditions (Ar/O2 mixing ratio, electrode arrangement). GDC system was designed and built on the basis of simulation to verify the GDC results. Moreover, we analyzed the influence of GDC on the surface of the optical components. It is found that the average density of metastable particles increases with the increase of oxygen-to-argon ratio. The arrangement of a single electrode is more reasonable for GDC compared with dual electrodes. From the results of quadrupole mass spectrum analysis, we identify that the amount of oil molecules could be reduced by 84% after being cleaned by glow discharge, indicating that GDC has a remarkable effect on removing oil molecules on the surface of the mirror box. However, we found that GDC has some damage to the optical element surface.

Mossbauer spectra of Ferrifol® measured at 295, 220, 140 and 90 K demonstrated non-Lorentzian two-peak spectra which were better fitted using a superposition of 5 quadrupole doublets with different quadrupole splitting but similar isomer shift and equal line width. Unusual line broadening was observed in the Mossbauer spectra of Ferrifol® measured in this temperature range. This is consistent with the unusual line broadening already observed earlier in the Mossbauer spectra (295–90 K) of ferritin and its pharmaceutical analogues Ferrum Lek and Maltofer® (Oshtrakh M.I. et al., Spectrochim. Acta, Part A: Mol. Biomol. Spectrosc., 2017, 172, 14–24, DOI: 10.1016/j.saa.2016.06.034). The Mossbauer spectrum of Ferrifol® at 60 K demonstrated a slow decrease of magnetic relaxation in the iron core. Magnetization measurements revealed mainly paramagnetic state of the Ferrifol® iron core and apparently blocking temperature around 33 K.

The High-Intensity Heavy Ion Accelerator Facility (HIAF) will provide intermediate charge state ion 238U35+ with intensity up to 2 × 1011 particle per pulse (ppp) to different experiments. However, large dynamic vacuum pressure rises of orders of magnitude, caused by lost heavy ions can seriously limit the maximum ion intensity and beam lifetime. Therefore, in order to predict the dynamic vacuum effects induced by the ionization beam loss for the BRing in the HIAF project, a new simulation program (ColBeam) has been developed together with GSI's simulation code StrahlSim are both conducted. The calculation algorithm for dynamic vacuum effect is introduced in this paper. According to the simulation result, up to 3 × 1011 ppp 238U35+ particles can be extracted for the current designed BRing vacuum and collimation system, which testifies the rationality of the system design and achieves the requirements of the physics experiments. Higher beam intensity can reach to 5 × 1011 ppp if the Non-Evaporable Getter (NEG) coating technology is implemented on the dipole and quadrupole chamber to further suppress the dynamic vacuum effect. The total vacuum pressure evolution with time in the BRing is shown in three-dimensional figure to explain the dynamic vacuum effect induced by the charge exchanged beam loss. The self-developed simulation program was implemented at 320 kV high voltage platform in IMP to simulate the dynamic vacuum evolution and compared with the measured vacuum pressure. Based on the simulation and benchmark results with the experimental data, it is concluded that the software can be used to confirm that dynamic vacuum effect can be suppressed by the collimation system and high speed pump distribution in the BRing.

The Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) accelerates beam from 80 MeV to 1.6 GeV to strike a solid metal target to produce spallation neutrons with a repetition rate of 25 Hz. In this kind of high bunch intensity synchrotrons, to suppress the space-charge effect, the large acceptance is always required. For CSNS, with the design acceptance of 540 π mm ⋅ mrad, the apertures of quadrupoles are quite large, which are comparable to the effective magnet lengths. In this case, the fringe field effect cannot be neglected. For some quadrupoles, the interval between the quadrupole and its neighbor magnet is comparable to the aperture of quadrupole, and the effect of field interference need to be considered. The fringe field and field interference effects have been studied, and by including these effects, the lattice was re-matched based on slicing model of quadrupoles to include these effects. After the re-matched lattice was applied to the beam commissioning of the RCS of CSNS, the measured twiss parameters are very close to the design parameters.

The changes of concentrations of O2 and CO2 in tail gas of fermentation industry reflect some important physiological and metabolic parameters in the fermentation process. Monitoring of the tail gas of fermentation has important significance for guiding the fermentation process. However, traditional monitoring methods are time-consuming with low precision and poor versatility, and are not suitable to monitor fermentation tail gas accurately in real time. In the process mass spectrometry, the traditional 70 eV electron impact ionization source will produce a large number of fragment ions, which may overlap with different substances, thus increasing the difficulty of qualitative analysis and causing inaccurate monitoring results. In order to realize real-time, on-line accurate monitoring of fermentation tail gas, a quadrupole process mass spectrometry based on electron impact ionization was developed for on-line analysis in this study. Through investigation of the relationship between emission current of filament and the electron receiving pole at low ionization energy, the ionization efficiency of the electron impact ionization source under low ionization energy mode was improved, and CO2, O2 and N2 were tested. The results showed that under the conditions of electron energy of 22 eV, electron receiving electrode of −22 V and filament emission current of 20–25 mA, the relative errors of quantitative detection of CO2 with volume fraction of higher than 0.023% and O2 with volume fraction of higher than 0.021% were all less than 1%. The instrument and the developed method had ideal application prospect in the rapid real-time, on-line monitoring of industrial processes.

We study the nuclear magnetic relaxation rate and Knight shift in the presence of the orbital and quadrupole interactions for three-dimensional Dirac electron systems (e.g., bismuth-antimony alloys). By using recent results of the dynamic magnetic susceptibility and permittivity, we obtain rigorous results of the relaxation rates $(1/T_1)_{\rm orb}$ and $(1/T_1)_{\rm Q}$, which are due to the orbital and quadrupole interactions, respectively, and show that $(1/T_1)_{\rm Q}$ gives a negligible contribution compared with $(1/T_1)_{\rm orb}$. It is found that $(1/T_1)_{\rm orb}$ exhibits anomalous dependences on temperature $T$ and chemical potential $\mu$. When $\mu$ is inside the band gap, $(1/T_1)_{\rm orb} \sim T ^3 \log (2 T/\omega_0)$ for temperatures above the band gap, where $\omega_0$ is the nuclear Larmor frequency. When $\mu$ lies in the conduction or valence bands, $(1/T_1)_{\rm orb} \propto T k_{\rm F}^2 \log (2 |v_{\rm F}| k_{\rm F}/\omega_0)$ for low temperatures, where $k_{\rm F}$ and $v_{\rm F}$ are the Fermi momentum and Fermi velocity, respectively. The Knight shift $K_{\rm orb}$ due to the orbital interaction also shows anomalous dependences on $T$ and $\mu$. It is shown that $K_{\rm orb}$ is negative and its magnitude significantly increases with decreasing temperature when $\mu$ is located in the band gap. Because the anomalous dependences in $K_{\rm orb}$ is caused by the interband particle-hole excitations across the small band gap while $\left( 1/T_1 \right)_{\rm orb}$ is governed by the intraband excitations, the Korringa relation does not hold in the Dirac electron systems., Comment: 12 pages, 1 figure

The positron linac of SuperKEKB contains accelerating structures surrounded by quadrupoles without nearby beam-position-monitors (BPMs) or steering magnets. In this situation, standard techniques for beam steering or beam-based-alignment are not efficient. We here present a method to determine the magnetic centers of individual SuperKEKB linac quadrupoles. This method is independent of any BPM offsets. The beam position at the quadrupole under study is scanned, and for each position the quadrupole strength is varied, so as to find the location of zero deflection. Unlike other method used in the past, this technique does not rely on any transfer matrices. Interpolation is possible even to quadrupoles without BPM by assigning ‘virtual BPMs’. We show that the misalignment of the quadrupoles with BPM in the bore can be determined with an rms error of ≤ 37 μ m; for quadrupoles without proper BPMs the error is σ ≤ 112 μ m.

High resolution emission spectra of atomic bismuth (209Bi I) have been observed in the spectral range from 2500 cm−1 to 40,000 cm−1 by means of a Fourier Transform spectrometer. Electrodeless discharge lamps containing BiI3 along with liquid-nitrogen cooled hollow cathode lamps containing Bi2O3 were utilized to generate the bismuth plasma. A total of 107 spectral lines were detected in the entire spectral region. Hyperfine structure (hfs) measurements were carried out on 76 lines, of which 21 were analyzed for the first time. Hfs magnetic dipole constant (A) and electric quadrupole constant (B) were determined for 31 energy levels. Hfs A constants for 6 levels and B constants for 8 levels are reported for the first time.