WorldWideScience

Sample records for spin resonance frequency

  1. Spin evolution in a radio frequency field studied through muon spin resonance.

    Science.gov (United States)

    Clayden, Nigel J; Cottrell, Stephen P; McKenzie, Iain

    2012-01-01

    The application of composite inversion pulses to a novel area of magnetic resonance, namely muon spin resonance, is demonstrated. Results confirm that efficient spin inversion can readily be achieved using this technique, despite the challenging experimental setup required for beamline measurements and the short lifetime (≈2.2μs) associated with the positive muon probe. Intriguingly, because the muon spin polarisation is detected by positron emission, the muon magnetisation can be monitored during the radio-frequency (RF) pulse to provide a unique insight into the effect of the RF field on the spin polarisation. This technique is used to explore the application of RF inversion sequences under the non-ideal conditions typically encountered when setting up pulsed muon resonance experiments. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. Radio frequency scanning tunneling spectroscopy for single-molecule spin resonance.

    Science.gov (United States)

    Müllegger, Stefan; Tebi, Stefano; Das, Amal K; Schöfberger, Wolfgang; Faschinger, Felix; Koch, Reinhold

    2014-09-26

    We probe nuclear and electron spins in a single molecule even beyond the electromagnetic dipole selection rules, at readily accessible magnetic fields (few mT) and temperatures (5 K) by resonant radio-frequency current from a scanning tunneling microscope. We achieve subnanometer spatial resolution combined with single-spin sensitivity, representing a 10 orders of magnitude improvement compared to existing magnetic resonance techniques. We demonstrate the successful resonant spectroscopy of the complete manifold of nuclear and electronic magnetic transitions of up to ΔI(z)=±3 and ΔJ(z)=±12 of single quantum spins in a single molecule. Our method of resonant radio-frequency scanning tunneling spectroscopy offers, atom-by-atom, unprecedented analytical power and spin control with an impact on diverse fields of nanoscience and nanotechnology.

  3. Field and frequency modulated sub-THz electron spin resonance spectrometer

    Directory of Open Access Journals (Sweden)

    Christian Caspers

    2016-05-01

    Full Text Available 260-GHz radiation is used for a quasi-optical electron spin resonance (ESR spectrometer which features both field and frequency modulation. Free space propagation is used to implement Martin-Puplett interferometry with quasi-optical isolation, mirror beam focusing, and electronic polarization control. Computer-aided design and polarization pathway simulation lead to the design of a compact interferometer, featuring lateral dimensions less than a foot and high mechanical stability, with all components rated for power levels of several Watts suitable for gyrotron radiation. Benchmark results were obtained with ESR standards (BDPA, DPPH using field modulation. Original high-field ESR of 4f electrons in Sm3+-doped Ceria was detected using frequency modulation. Distinct combinations of field and modulation frequency reach a signal-to-noise ratio of 35 dB in spectra of BDPA, corresponding to a detection limit of about 1014 spins.

  4. Spin-torque diode radio-frequency detector with voltage tuned resonance

    Energy Technology Data Exchange (ETDEWEB)

    Skowroński, Witold, E-mail: skowron@agh.edu.pl; Frankowski, Marek; Stobiecki, Tomasz [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland); Wrona, Jerzy [AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland); Singulus Technologies, Kahl am Main 63796 (Germany); Ogrodnik, Piotr [Faculty of Physics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw (Poland); AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Kraków (Poland); Barnaś, Józef [Faculty of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland); Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań (Poland)

    2014-08-18

    We report on a voltage-tunable radio-frequency (RF) detector based on a magnetic tunnel junction (MTJ). The spin-torque diode effect is used to excite and/or detect RF oscillations in the magnetic free layer of the MTJ. In order to reduce the overall in-plane magnetic anisotropy of the free layer, we take advantage of the perpendicular magnetic anisotropy at the interface between ferromagnetic and insulating layers. The applied bias voltage is shown to have a significant influence on the magnetic anisotropy, and thus on the resonance frequency of the device. This influence also depends on the voltage polarity. The obtained results are accounted for in terms of the interplay of spin-transfer-torque and voltage-controlled magnetic anisotropy effects.

  5. Spin-wave resonance frequency in ferromagnetic thin film with interlayer exchange coupling and surface anisotropy

    Science.gov (United States)

    Zhang, Shuhui; Rong, Jianhong; Wang, Huan; Wang, Dong; Zhang, Lei

    2018-01-01

    We have investigated the dependence of spin-wave resonance(SWR) frequency on the surface anisotropy, the interlayer exchange coupling, the ferromagnetic layer thickness, the mode number and the external magnetic field in a ferromagnetic superlattice film by means of the linear spin-wave approximation and Green's function technique. The SWR frequency of the ferromagnetic thin film is shifted to higher values corresponding to those of above factors, respectively. It is found that the linear behavior of SWR frequency curves of all modes in the system is observed as the external magnetic field is increasing, however, SWR frequency curves are nonlinear with the lower and the higher modes for different surface anisotropy and interlayer exchange coupling in the system. In addition, the SWR frequency of the lowest (highest) mode is shifted to higher (lower) values when the film thickness is thinner. The interlayer exchange coupling is more important for the energetically higher modes than for the energetically lower modes. The surface anisotropy has a little effect on the SWR frequency of the highest mode, when the surface anisotropy field is further increased.

  6. Effect of antiferromagnetic interfacial coupling on spin-wave resonance frequency of multi-layer film

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Rong-ke, E-mail: rkqiu@163.com; Cai, Wei

    2017-08-15

    Highlights: • A quantum approach is developed to study the SWR of a bicomponent multi-layer films. • The comparison of the SWR in films with FM and AFM interfacial coupling has been made. • The present results show the method to enhance and adjust the SWR frequency of films. - Abstract: We investigate the spin-wave resonance (SWR) frequency in a bicomponent bilayer and triple-layer films with antiferromagnetic or ferromagnetic interfacial couplings, as function of interfacial coupling, surface anisotropy, interface anisotropy, thickness and external magnetic field, using the linear spin-wave approximation and Green’s function technique. The microwave properties for multi-layer magnetic film with antiferromagnetic interfacial coupling is different from those for multi-layer magnetic film with ferromagnetic interfacial coupling. For the bilayer film with antiferromagnetic interfacial couplings, as the lower (upper) surface anisotropy increases, only the SWR frequencies of the odd (even) number modes increase. The lower (upper) surface anisotropy does not affect the SWR frequencies of the even (odd) number modes{sub .} For the multi-layer film with antiferromagnetic interfacial coupling, the SWR frequency of modes m = 1, 3 and 4 decreases while that of mode m = 2 increases with increasing thickness of the film within a proper parameter region. The present results could be useful in enhancing our fundamental understanding and show the method to enhance and adjust the SWR frequency of bicomponent multi-layer magnetic films with antiferromagnetic or ferromagnetic interfacial coupling.

  7. Generation of constant-amplitude radio-frequency sweeps at a tunnel junction for spin resonance STM

    International Nuclear Information System (INIS)

    Paul, William; Lutz, Christopher P.; Heinrich, Andreas J.; Baumann, Susanne

    2016-01-01

    We describe the measurement and successful compensation of the radio-frequency transfer function of a scanning tunneling microscope over a wide frequency range (15.5–35.5 GHz) and with high dynamic range (>50 dB). The precise compensation of cabling resonances and attenuations is critical for the production of constant-voltage frequency sweeps for electric-field driven electron spin resonance (ESR) experiments. We also demonstrate that a well-calibrated tunnel junction voltage is necessary to avoid spurious ESR peaks that can arise due to a non-flat transfer function.

  8. Multi-frequency force-detected electron spin resonance in the millimeter-wave region up to 150 GHz

    Energy Technology Data Exchange (ETDEWEB)

    Ohmichi, E., E-mail: ohmichi@harbor.kobe-u.ac.jp; Tokuda, Y.; Tabuse, R.; Tsubokura, D.; Okamoto, T. [Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan); Ohta, H. [Molecular Photoscience Research Center, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501 (Japan)

    2016-07-15

    In this article, a novel technique is developed for multi-frequency force-detected electron spin resonance (ESR) in the millimeter-wave region. We constructed a compact ESR probehead, in which the cantilever bending is sensitively detected by a fiber-optic Fabry-Perot interferometer. With this setup, ESR absorption of diphenyl-picrylhydrazyl radical (<1 μg) was clearly observed at multiple frequencies of up to 150 GHz. We also observed the hyperfine splitting of low-concentration Mn{sup 2+} impurities(∼0.2%) in MgO.

  9. Multi-resonance frequency spin dependent charge pumping and spin dependent recombination - applied to the 4H-SiC/SiO2 interface

    Science.gov (United States)

    Anders, M. A.; Lenahan, P. M.; Lelis, A. J.

    2017-12-01

    We report on a new electrically detected magnetic resonance (EDMR) approach involving spin dependent charge pumping (SDCP) and spin dependent recombination (SDR) at high (K band, about 16 GHz) and ultra-low (360 and 85 MHz) magnetic resonance frequencies to investigate the dielectric/semiconductor interface in 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs). A comparison of SDCP and SDR allows for a comparison of deep level defects and defects with energy levels throughout most of the bandgap. Additionally, a comparison of high frequency and ultra-low frequency measurements allows for (1) the partial separation of spin-orbit coupling and hyperfine effects on magnetic resonance spectra, (2) the observation of otherwise forbidden half-field effects, which make EDMR, at least, in principle, quantitative, and (3) the observation of Breit-Rabi shifts in superhyperfine measurements. (Observation of the Breit-Rabi shift helps in both the assignment and the measurement of superhyperfine parameters.) We find that, as earlier work also indicates, the SiC silicon vacancy is the dominating defect in n-MOSFETs with as-grown oxides and that post-oxidation NO anneals significantly reduce their population. In addition, we provide strong evidence that NO anneals result in the presence of nitrogen very close to a large fraction of the silicon vacancies. The results indicate that the presence of nearby nitrogen significantly shifts the silicon vacancy energy levels. Our results also show that the introduction of nitrogen introduces a disorder at the interface. This nitrogen induced disorder may provide at least a partial explanation for the relatively modest improvement in mobility after the NO anneals. Finally, we compare the charge pumping and SDCP response as a function of gate amplitude and charge pumping frequency.

  10. Resonant Tunneling Spin Pump

    Science.gov (United States)

    Ting, David Z.

    2007-01-01

    The resonant tunneling spin pump is a proposed semiconductor device that would generate spin-polarized electron currents. The resonant tunneling spin pump would be a purely electrical device in the sense that it would not contain any magnetic material and would not rely on an applied magnetic field. Also, unlike prior sources of spin-polarized electron currents, the proposed device would not depend on a source of circularly polarized light. The proposed semiconductor electron-spin filters would exploit the Rashba effect, which can induce energy splitting in what would otherwise be degenerate quantum states, caused by a spin-orbit interaction in conjunction with a structural-inversion asymmetry in the presence of interfacial electric fields in a semiconductor heterostructure. The magnitude of the energy split is proportional to the electron wave number. Theoretical studies have suggested the possibility of devices in which electron energy states would be split by the Rashba effect and spin-polarized currents would be extracted by resonant quantum-mechanical tunneling.

  11. Electron spin resonance

    International Nuclear Information System (INIS)

    Wasson, J.R.; Salinas, J.E.

    1980-01-01

    Published literature concerning electron spin resonance (ESR) from July 1977 to July 1979 is reviewed. The 108 literature sources cited were chosen from literally thousands and are intended to serve as a guide to the current literature and to provide an eclectic selection of publications cited for their contributions to the advance and/or applications of ESR spectroscopy. 40 of the sources are reviews, and a table is included to indicate the topic(s) mainly covered in each review. Other divisions of the material reviewed are apparatus and spectral analysis, analytical applications, and selected paramagnetic materials

  12. Large Mn25 single-molecule magnet with spin S = 51/2: magnetic and high-frequency electron paramagnetic resonance spectroscopic characterization of a giant spin state.

    Science.gov (United States)

    Murugesu, Muralee; Takahashi, Susumu; Wilson, Anthony; Abboud, Khalil A; Wernsdorfer, Wolfgang; Hill, Stephen; Christou, George

    2008-10-20

    The synthesis and structural, spectroscopic, and magnetic characterization of a Mn25 coordination cluster with a large ground-state spin of S = 51/2 are reported. Reaction of MnCl2 with pyridine-2,6-dimethanol (pdmH2) and NaN3 in MeCN/MeOH gives the mixed valence cluster [Mn25O18(OH)2(N3)12(pdm)6(pdmH)6]Cl2 (1; 6Mn(II), 18Mn(III), Mn(IV)), which has a barrel-like cage structure. Variable temperature direct current (dc) magnetic susceptibility data were collected in the 1.8-300 K temperature range in a 0.1 T field. Variable-temperature and -field magnetization (M) data were collected in the 1.8-4.0 K and 0.1-7 T ranges and fit by matrix diagonalization assuming only the ground state is occupied at these temperatures. The fit parameters were S = 51/2, D = -0.020(2) cm(-1), and g = 1.87(3), where D is the axial zero-field splitting parameter. Alternating current (ac) susceptibility measurements in the 1.8-8.0 K range and a 3.5 G ac field oscillating at frequencies in the 50-1500 Hz range revealed a frequency-dependent out-of-phase (chi(M)'') signal below 3 K, suggesting 1 to be a single-molecule magnet (SMM). This was confirmed by magnetization vs dc field sweeps, which exhibited hysteresis loops but with no clear steps characteristic of resonant quantum tunneling of magnetization (QTM). However, magnetization decay data below 1 K were collected and used to construct an Arrhenius plot, and the fit of the thermally activated region above approximately 0.5 K gave U(eff)/k = 12 K, where U(eff) is the effective relaxation barrier. The g value and the magnitude and sign of the D value were independently confirmed by detailed high-frequency electron paramagnetic resonance (HFEPR) spectroscopy on polycrystalline samples. The combined studies confirm both the high ground-state spin S = 51/2 of complex 1 and that it is a SMM that, in addition, exhibits QTM.

  13. High-Frequency and -Field Electron Paramagnetic Resonance of High-Spin Manganese(III) in Porphyrinic Complexes.

    Science.gov (United States)

    Krzystek, J.; Telser, Joshua; Pardi, Luca A.; Goldberg, David P.; Hoffman, Brian M.; Brunel, Louis-Claude

    1999-12-27

    High-field and -frequency electron paramagnetic resonance (HFEPR) spectroscopy has been used to study two complexes of high-spin manganese(III), d(4), S = 2. The complexes studied were (tetraphenylporphyrinato)manganese(III) chloride and (phthalocyanato)manganese(III) chloride. Our previous HFEPR study (Goldberg, D. P.; Telser, J.; Krzystek, J.; Montalban, A. G.; Brunel, L.-C.; Barrett, A. G. M.; Hoffman, B. M. J. Am. Chem. Soc. 1997, 119, 8722-8723) included results on the porphyrin complex; however, we were unable to obtain true powder pattern HFEPR spectra, as the crystallites oriented in the intense external magnetic field. In this work we are now able to immobilize the powder, either in an n-eicosane mull or KBr pellet and obtain true powder pattern spectra. These spectra have been fully analyzed using spectral simulation software, and a complete set of spin Hamiltonian parameters has been determined for each complex. Both complexes are rigorously axial systems, with relatively low magnitude zero-field splitting: D approximately -2.3 cm(-)(1) and g values quite close to 2.00. Prior to this work, no experimental nor theoretical data exist for the metal-based electronic energy levels in Mn(III) complexes of porphyrinic ligands. This lack of information is in contrast to other transition metal complexes and is likely due to the dominance of ligand-based transitions in the absorption spectra of Mn(III) complexes of this type. We have therefore made use of theoretical values for the electronic energy levels of (phthalocyanato)copper(II), which electronically resembles these Mn(III) complexes. This analogy works surprisingly well in terms of the agreement between the calculated and experimentally determined EPR parameters. These results show a significant mixing of the triplet (S = 1) excited state with the quintet (S = 2) ground state in Mn(III) complexes with porphyrinic ligands. This is in agreement with the experimental observation of lower spin ground states in

  14. Measuring the spin polarization of alkali-metal atoms using nuclear magnetic resonance frequency shifts of noble gases

    Directory of Open Access Journals (Sweden)

    X. H. Liu

    2015-10-01

    Full Text Available We report a novel method of measuring the spin polarization of alkali-metal atoms by detecting the NMR frequency shifts of noble gases. We calculated the profile of 87Rb D1 line absorption cross sections. We then measured the absorption profile of the sample cell, from which we calculated the 87Rb number densities at different temperatures. Then we measured the frequency shifts resulted from the spin polarization of the 87Rb atoms and calculated its polarization degrees at different temperatures. The behavior of frequency shifts versus temperature in experiment was consistent with theoretical calculation, which may be used as compensative signal for the NMRG closed-loop control system.

  15. Spin determination of fission resonances

    International Nuclear Information System (INIS)

    Keyworth, G.A.

    1976-01-01

    The present status of available information on the channel quantum numbers for resonance fission and the most urgently needed additional experiments are examined. The role of spin in the 235 U + n system is emphasized. The discussion relies heavily on recent alignment measurements and polarization results

  16. Simple classical approach to spin resonance phenomena

    DEFF Research Database (Denmark)

    Gordon, R A

    1977-01-01

    A simple classical method of describing spin resonance in terms of the average power absorbed by a spin system is discussed. The method has several advantages over more conventional treatments, and a number of important spin resonance phenomena, not normally considered at the introductory level...

  17. Unexpected enhancements and reductions of rf spin resonance strengths

    Directory of Open Access Journals (Sweden)

    M. A. Leonova

    2006-05-01

    Full Text Available We recently analyzed all available data on spin-flipping stored beams of polarized protons, electrons, and deuterons. Fitting the modified Froissart-Stora equation to the measured polarization data after crossing an rf-induced spin resonance, we found 10–20-fold deviations from the depolarizing resonance strength equations used for many years. The polarization was typically manipulated by linearly sweeping the frequency of an rf dipole or rf solenoid through an rf-induced spin resonance; spin-flip efficiencies of up to 99.9% were obtained. The Lorentz invariance of an rf dipole’s transverse ∫Bdl and the weak energy dependence of its spin resonance strength E together imply that even a small rf dipole should allow efficient spin flipping in 100 GeV or even TeV storage rings; thus, it is important to understand these large deviations. Therefore, we recently studied the resonance strength deviations experimentally by varying the size and vertical betatron tune of a 2.1  GeV/c polarized proton beam stored in COSY. We found no dependence of E on beam size, but we did find almost 100-fold enhancements when the rf spin resonance was near an intrinsic spin resonance.

  18. Effect of high-frequency excitation on natural frequencies of spinning discs

    DEFF Research Database (Denmark)

    Hansen, Morten Hartvig

    2000-01-01

    The effect of high-frequency, non-resonant parametric excitation on the low-frequency response of spinning discs is considered. The parametric excitation is obtained through a non-constant rotation speed, where the frequency of the pulsating overlay is much higher than the lowest natural frequenc......The effect of high-frequency, non-resonant parametric excitation on the low-frequency response of spinning discs is considered. The parametric excitation is obtained through a non-constant rotation speed, where the frequency of the pulsating overlay is much higher than the lowest natural...

  19. Double-spin-flip resonance of rhodium nuclei at positive and negative spin temperatures

    DEFF Research Database (Denmark)

    Tuoriniemi, J.T.; Knuuttila, T.A.; Lefmann, K.

    2000-01-01

    Sensitive SQUID-NMR measurements were used to study the mutual interactions in the highly polarized nuclear-spin system of rhodium metal. The dipolar coupling gives rise to a weak double-spin-flip resonance. The observed frequency shifts allow deducing separately the dipolarlike contribution...

  20. Resonance frequency analysis

    Directory of Open Access Journals (Sweden)

    Rajiv K Gupta

    2011-01-01

    Full Text Available Initial stability at the placement and development of osseointegration are two major issues for implant survival. Implant stability is a mechanical phenomenon which is related to the local bone quality and quantity, type of implant, and placement technique used. The application of a simple, clinically applicable, non-invasive test to assess implant stability and osseointegration is considered highly desirable. Resonance frequency analysis (RFA is one of such techniques which is most frequently used now days. The aim of this paper was to review and analyze critically the current available literature in the field of RFA, and to also discuss based on scientific evidence, the prognostic value of RFA to detect implants at risk of failure. A search was made using the PubMed database to find all the literature published on "Resonance frequency analysis for implant stability" till date. Articles discussed in vivo or in vitro studies comparing RFA with other methods of implant stability measurement and articles discussing its reliability were thoroughly reviewed and discussed. A limited number of clinical reports were found. Various studies have demonstrated the feasibility and predictability of the technique. However, most of these articles are based on retrospective data or uncontrolled cases. Randomized, prospective, parallel-armed longitudinal human trials are based on short-term results and long-term follow up are still scarce in this field. Nonetheless, from available literature, it may be concluded that RFA technique evaluates implant stability as a function of stiffness of the implant bone interface and is influenced by factors such as bone type, exposed implant height above the alveolar crest. Resonance frequency analysis could serve as a non-invasive diagnostic tool for detecting the implant stability of dental implants during the healing stages and in subsequent routine follow up care after treatment. Future studies, preferably randomized

  1. Coherent electron-spin-resonance manipulation of three individual spins in a triple quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Noiri, A. [Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Yoneda, J.; Nakajima, T.; Otsuka, T.; Delbecq, M. R.; Takeda, K.; Tarucha, S. [Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); RIKEN, Center for Emergent Matter Science (CEMS), Wako-shi, Saitama 351-0198 (Japan); Amaha, S.; Allison, G. [RIKEN, Center for Emergent Matter Science (CEMS), Wako-shi, Saitama 351-0198 (Japan); Ludwig, A.; Wieck, A. D. [Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany)

    2016-04-11

    Quantum dot arrays provide a promising platform for quantum information processing. For universal quantum simulation and computation, one central issue is to demonstrate the exhaustive controllability of quantum states. Here, we report the addressable manipulation of three single electron spins in a triple quantum dot using a technique combining electron-spin-resonance and a micro-magnet. The micro-magnet makes the local Zeeman field difference between neighboring spins much larger than the nuclear field fluctuation, which ensures the addressable driving of electron-spin-resonance by shifting the resonance condition for each spin. We observe distinct coherent Rabi oscillations for three spins in a semiconductor triple quantum dot with up to 25 MHz spin rotation frequencies. This individual manipulation over three spins enables us to arbitrarily change the magnetic spin quantum number of the three spin system, and thus to operate a triple-dot device as a three-qubit system in combination with the existing technique of exchange operations among three spins.

  2. Spin with two snakes and overlapping resonances

    International Nuclear Information System (INIS)

    Lee, S.Y.; Zhao, X.F.

    1987-01-01

    We study the effect of multiple spin depolarization resonances on the spin of the particles with two snakes. When two resonances are well separated, the polarization can be restored in passing through these resonances provided that the snake resonances are avoided. When two resonances are overlapping, the beam particles may be depolarized depending on the spacing between these two resonances. If the spacing between these two resonances is an odd number for two snakes, the beam particles may be depolarized depending on the strength of the resonance. When the spacing becomes an even number, the spin can tolerate a much larger resonance strength without depolarization. Numerical simulations can be shown to agree well with the analytic formula. However, the spin is susceptible to the combination of an intrinsic and an imperfection resonances even in the presence of the snakes. Numerical simulation indicates that the spin can be restored after the resonances provided that imperfection strength is less than 0.1 if intrinsic strength is fixed at 0.745

  3. Spin with two snakes and overlapping resonances

    International Nuclear Information System (INIS)

    Lee, S.Y.; Zhao, X.F.

    1987-01-01

    The authors study the effect of multiple spin depolarization resonances on the spin of the particles with two snakes. They found that (1) When two resonances are well separated, the polarization can be restored in passing through these resonances provided that the snake resonances are avoided. (2) When two resonances are overlapping, the beam particles may be depolarized depending on the spacing between these two resonances. If the spacing between these two resonances is an odd number for two snakes, the beam particles may be depolarized depending on the strength of the resonance. When the spacing becomes an even number, the spin can tolerate a much larger resonance strength without depolarization. Numerical simulations can be shown to agree with the analytic formula. (3) However the spin is susceptible to the combination of an intrinsic and an imperfection resonances even in the present of the snakes. Numerical solutions indicates that the spin can be restored after the resonances provided that imperfection strength is less than 0.1 if intrinsic strength is fixed at 0.745

  4. Rabi resonance in spin systems: theory and experiment.

    Science.gov (United States)

    Layton, Kelvin J; Tahayori, Bahman; Mareels, Iven M Y; Farrell, Peter M; Johnston, Leigh A

    2014-05-01

    The response of a magnetic resonance spin system is predicted and experimentally verified for the particular case of a continuous wave amplitude modulated radiofrequency excitation. The experimental results demonstrate phenomena not previously observed in magnetic resonance systems, including a secondary resonance condition when the amplitude of the excitation equals the modulation frequency. This secondary resonance produces a relatively large steady state magnetisation with Fourier components at harmonics of the modulation frequency. Experiments are in excellent agreement with the theoretical prediction derived from the Bloch equations, which provides a sound theoretical framework for future developments in NMR spectroscopy and imaging. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    Directory of Open Access Journals (Sweden)

    N. I. Polzikova

    2016-05-01

    Full Text Available We present the generation and detection of spin currents by using magnetoelastic resonance excitation in a magnetoelectric composite high overtone bulk acoustic wave (BAW resonator (HBAR formed by a Al-ZnO-Al-GGG-YIG-Pt structure. Transversal BAW drives magnetization oscillations in YIG film at a given resonant magnetic field, and the resonant magneto-elastic coupling establishes the spin-current generation at the Pt/YIG interface. Due to the inverse spin Hall effect (ISHE this BAW-driven spin current is converted to a dc voltage in the Pt layer. The dependence of the measured voltage both on magnetic field and frequency has a resonant character. The voltage is determined by the acoustic power in HBAR and changes its sign upon magnetic field reversal. We compare the experimentally observed amplitudes of the ISHE electrical field achieved by our method and other approaches to spin current generation that use surface acoustic waves and microwave resonators for ferromagnetic resonance excitation, with the theoretically expected values.

  6. Acoustic spin pumping in magnetoelectric bulk acoustic wave resonator

    Energy Technology Data Exchange (ETDEWEB)

    Polzikova, N. I., E-mail: polz@cplire.ru; Alekseev, S. G.; Pyataikin, I. I.; Kotelyanskii, I. M.; Luzanov, V. A.; Orlov, A. P. [Kotel’nikov Institute of Radio Engineering and Electronics of Russian Academy of Sciences, Mokhovaya 11, building 7, Moscow, 125009 (Russian Federation)

    2016-05-15

    We present the generation and detection of spin currents by using magnetoelastic resonance excitation in a magnetoelectric composite high overtone bulk acoustic wave (BAW) resonator (HBAR) formed by a Al-ZnO-Al-GGG-YIG-Pt structure. Transversal BAW drives magnetization oscillations in YIG film at a given resonant magnetic field, and the resonant magneto-elastic coupling establishes the spin-current generation at the Pt/YIG interface. Due to the inverse spin Hall effect (ISHE) this BAW-driven spin current is converted to a dc voltage in the Pt layer. The dependence of the measured voltage both on magnetic field and frequency has a resonant character. The voltage is determined by the acoustic power in HBAR and changes its sign upon magnetic field reversal. We compare the experimentally observed amplitudes of the ISHE electrical field achieved by our method and other approaches to spin current generation that use surface acoustic waves and microwave resonators for ferromagnetic resonance excitation, with the theoretically expected values.

  7. Theoretical foundations of electron spin resonance

    CERN Document Server

    Harriman, John E

    2013-01-01

    Theoretical Foundations of Electron Spin Resonance deals with the theoretical approach to electron paramagnetic resonance. The book discusses electron spin resonance in applications related to polyatomic, probably organic, free radicals in condensed phases. The book also focuses on essentially static phenomena, that is, the description and determination of stationary-state energy levels. The author reviews the Dirac theory of the electron in which a four-component wave function is responsible for the behavior of the electron. The author then connects this theory with the nonrelativistic wave f

  8. Model for electron spin resonance in STM noise

    Science.gov (United States)

    Caso, Alvaro; Horovitz, Baruch; Arrachea, Liliana

    2014-02-01

    We propose a model to account for the observed ESR-like signal at the Larmor frequency in the current noise scanning tunnel microscope (STM) experiments identifying spin centers on various substrates. The theoretical understanding of this phenomenon, which allows for single spin detection on surfaces at room temperature, is not settled for the experimentally relevant case that the tip and substrate are not spin polarized. Our model is based on a direct tip-substrate tunneling in parallel with a current flowing via the spin states. We find a sharp signal at the Larmor frequency even at high temperatures, in good agreement with experimental data. We also evaluate the noise in presence of an ac field near resonance and predict splitting of the signal into a Mollow triplet.

  9. Parameter dependence of resonant spin torque magnetization reversal

    International Nuclear Information System (INIS)

    Fricke, L.; Serrano-Guisan, S.; Schumacher, H.W.

    2012-01-01

    We numerically study ultra fast resonant spin torque (ST) magnetization reversal in magnetic tunneling junctions (MTJ) driven by current pulses having a direct current (DC) and a resonant alternating current (AC) component. The precessional ST dynamics of the single domain MTJ free layer cell are modeled in the macro spin approximation. The energy efficiency, reversal time, and reversal reliability are investigated under variation of pulse parameters like direct and AC current amplitude, AC frequency and AC phase. We find a range of AC and direct current amplitudes where robust resonant ST reversal is obtained with faster switching time and reduced energy consumption per pulse compared to purely direct current ST reversal. However, for a certain range of AC and direct current amplitudes a strong dependence of the reversal properties on AC frequency and phase is found. Such regions of unreliable reversal must be avoided for ST memory applications.

  10. Parameter dependence of resonant spin torque magnetization reversal

    Science.gov (United States)

    Fricke, L.; Serrano-Guisan, S.; Schumacher, H. W.

    2012-04-01

    We numerically study ultra fast resonant spin torque (ST) magnetization reversal in magnetic tunneling junctions (MTJ) driven by current pulses having a direct current (DC) and a resonant alternating current (AC) component. The precessional ST dynamics of the single domain MTJ free layer cell are modeled in the macro spin approximation. The energy efficiency, reversal time, and reversal reliability are investigated under variation of pulse parameters like direct and AC current amplitude, AC frequency and AC phase. We find a range of AC and direct current amplitudes where robust resonant ST reversal is obtained with faster switching time and reduced energy consumption per pulse compared to purely direct current ST reversal. However, for a certain range of AC and direct current amplitudes a strong dependence of the reversal properties on AC frequency and phase is found. Such regions of unreliable reversal must be avoided for ST memory applications.

  11. Frequency Modulation of Spin-Transfer Oscillators

    OpenAIRE

    Pufall, M. R.; Rippard, W. H.; Kaka, S.; Silva, T. J.; Russek, S. E.

    2004-01-01

    Spin-polarized dc electric current flowing into a magnetic layer can induce precession of the magnetization at a frequency that depends on current. We show that addition of an ac current to this dc bias current results in a frequency modulated (FM) spectral output, generating sidebands spaced at the modulation frequency. The sideband amplitudes and shift of the center frequency with drive amplitude are in good agreement with a nonlinear FM model that takes into account the nonlinear frequency...

  12. Neutron resonance spin echo with longitudinal DC fields

    Science.gov (United States)

    Krautloher, Maximilian; Kindervater, Jonas; Keller, Thomas; Häußler, Wolfgang

    2016-12-01

    We report on the design, construction, and performance of a neutron resonance spin echo (NRSE) instrument employing radio frequency (RF) spin flippers combining RF fields with DC fields, the latter oriented parallel (longitudinal) to the neutron propagation direction (longitudinal NRSE (LNRSE)). The advantage of the longitudinal configuration is the inherent homogeneity of the effective magnetic path integrals. In the center of the RF coils, the sign of the spin precession phase is inverted by a π flip of the neutron spins, such that non-uniform spin precession at the boundaries of the RF flippers is canceled. The residual inhomogeneity can be reduced by Fresnel- or Pythagoras-coils as in the case of conventional spin echo instruments (neutron spin echo (NSE)). Due to the good intrinsic homogeneity of the B0 coils, the current densities required for the correction coils are at least a factor of three less than in conventional NSE. As the precision and the current density of the correction coils are the limiting factors for the resolution of both NSE and LNRSE, the latter has the intrinsic potential to surpass the energy resolution of present NSE instruments. Our prototype LNRSE spectrometer described here was implemented at the resonance spin echo for diverse applications (RESEDA) beamline at the MLZ in Garching, Germany. The DC fields are generated by B0 coils, based on resistive split-pair solenoids with an active shielding for low stray fields along the beam path. One pair of RF flippers at a distance of 2 m generates a field integral of ˜0.5 Tm. The LNRSE technique is a future alternative for high-resolution spectroscopy of quasi-elastic excitations. In addition, it also incorporates the MIEZE technique, which allows to achieve spin echo resolution for spin depolarizing samples and sample environments. Here we present the results of numerical optimization of the coil geometry and first data from the prototype instrument.

  13. Theory of electrically controlled resonant tunneling spin devices

    Science.gov (United States)

    Ting, David Z. -Y.; Cartoixa, Xavier

    2004-01-01

    We report device concepts that exploit spin-orbit coupling for creating spin polarized current sources using nonmagnetic semiconductor resonant tunneling heterostructures, without external magnetic fields. The resonant interband tunneling psin filter exploits large valence band spin-orbit interaction to provide strong spin selectivity.

  14. Effects of the electron-electron interaction in the spin resonance in 2D systems with Dresselhaus spin-orbit coupling

    International Nuclear Information System (INIS)

    Krishtopenko, S. S.

    2015-01-01

    The effect of the electron-electron interaction on the spin-resonance frequency in two-dimensional electron systems with Dresselhaus spin-orbit coupling is investigated. The oscillatory dependence of many-body corrections on the magnetic field is demonstrated. It is shown that the consideration of many-body interaction leads to a decrease or an increase in the spin-resonance frequency, depending on the sign of the g factor. It is found that the term cubic in quasimomentum in Dresselhaus spin-orbit coupling partially decreases exchange corrections to the spin resonance energy in a two-dimensional system

  15. Effects of the electron-electron interaction in the spin resonance in 2D systems with Dresselhaus spin-orbit coupling

    Energy Technology Data Exchange (ETDEWEB)

    Krishtopenko, S. S., E-mail: sergey.krishtopenko@mail.ru [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

    2015-02-15

    The effect of the electron-electron interaction on the spin-resonance frequency in two-dimensional electron systems with Dresselhaus spin-orbit coupling is investigated. The oscillatory dependence of many-body corrections on the magnetic field is demonstrated. It is shown that the consideration of many-body interaction leads to a decrease or an increase in the spin-resonance frequency, depending on the sign of the g factor. It is found that the term cubic in quasimomentum in Dresselhaus spin-orbit coupling partially decreases exchange corrections to the spin resonance energy in a two-dimensional system.

  16. Electron spin resonance in some Turkish coals

    Energy Technology Data Exchange (ETDEWEB)

    Korkmaz, M.; Ozbey, T. (Hacettepe University, Ankara (Turkey). Dept. of Physics)

    1991-06-01

    An electron spin resonance study of 12 Turkish coals in their raw state is presented. In almost all samples three main paramagnetic centres in the g{approximately} 4.3 and g{approximately}2.0 regions were observed. The g-values, linewidths, lineshapes and spin concentrations of the carbon free radicals were measured. While g-values fell, linewidths increased with increasing carbon content of the coals. Oxygen and sulphur contents played an important role in the determination of g-values. Linewidths and radical concentrations were found to increase with increasing hydrogen and carbon contents, respectively. 18 refs., 7 figs., 2 tabs.

  17. Single-pulse terahertz coherent control of spin resonance in the canted antiferromagnet YFeO3, mediated by dielectric anisotropy

    DEFF Research Database (Denmark)

    Jin, Zuanming; Mics, Zoltán; Ma, Guohong

    2013-01-01

    We report on the coherent control of terahertz (THz) spin waves in a canted antiferromagnet yttrium orthoferrite, YFeO3, associated with a quasiferromagnetic (quasi-FM) spin resonance at a frequency of 0.3 THz, using a single-incident THz pulse. The spin resonance is excited impulsively by the ma...... polarization of the THz oscillation at the spin resonance frequency, suggests a key role of magnon–phonon coupling in spin-wave energy dissipation....

  18. Electron-Spin Resonance in Boron Carbide

    Science.gov (United States)

    Wood, Charles; Venturini, Eugene L.; Azevedo, Larry J.; Emin, David

    1987-01-01

    Samples exhibit Curie-law behavior in temperature range of 2 to 100 K. Technical paper presents studies of electron-spin resonance of samples of hot pressed B9 C, B15 C2, B13 C2, and B4 C. Boron carbide ceramics are refractory solids with high melting temperatures, low thermal conductives, and extreme hardnesses. They show promise as semiconductors at high temperatures and have unusually large figures of merit for use in thermoelectric generators.

  19. Electron spin resonance identification of irradiated fruits

    International Nuclear Information System (INIS)

    Raffi, J.J.; Agnel, J.-P.L.

    1989-01-01

    The electron spin resonance spectrum of achenes, pips, stalks and stones from irradiated fruits (stawberry, raspberry, red currant, bilberry, apple, pear, fig, french prune, kiwi, water-melon and cherry) always displays, just after γ-treatment, a weak triplet (a H ∼30 G) due to a cellulose radical; its left line (lower field) can be used as an identification test of irradiation, at least for strawberries, raspberries, red currants or bilberries irradiated in order to improve their storage time. (author)

  20. Physics of Resonating Valence Bond Spin Liquids

    Science.gov (United States)

    Wildeboer, Julia Saskia

    This thesis will investigate various aspects of the physics of resonating valence bond spin liquids. After giving an introduction to the world that lies beyond Landau's priciple of symmetry breaking, e.g. giving an overview of exotic magnetic phases and how they can be described and (possibly) found, we will study a spin-rotationally invariant model system with a known parent Hamiltonian, and argue its ground state to lie within a highly sought after exotic phase, namely the Z2 quantum spin liquid phase. A newly developed numerical procedure --Pfaffian Monte Carlo-- will be introduced to amass evidence that our model Hamiltonian indeed exhibits a Z2 quantum spin liquid phase. Subsequently, we will prove a useful mathematical property of the resonating valence bond states: these states are shown to be linearly independent. Various lattices are investigated concerning this property, and its applications and usefullness are discussed. Eventually, we present a simplified model system describing the interplay of the well known Heisenberg interaction and the Dzyaloshinskii-Moriya (DM) interaction term acting on a sawtooth chain. The effect of the interplay between the two interaction couplings on the phase diagram is investigated. To do so, we employ modern techniques such as the density matrix renormalization group (DMRG) scheme. We find that for weak DM interaction the system exhibits valence bond order. However, a strong enough DM coupling destroys this order.

  1. Rf Depolarizing Resonances In The Presence Of A Full Siberian Snake And Full Snake Spin-flipping

    CERN Document Server

    Blinov, B B

    2000-01-01

    Frequent polarization reversals, or spin-flips, of a stored polarized beam in high energy scattering asymmetry experiments may greatly reduce systematic errors of spin asymmetry measurements. A spin-flipping technique is being developed by using rf magnets running at a frequency close to the spin precession frequency, thereby creating spin-depolarizing resonances; the spin can then be flipped by ramping the rf magnet's frequency through the resonance. We studied, at the Indiana University Cyclotron Facility Cooler Ring, properties of such rf depolarizing resonances in the presence of a nearly-full Siberian snake and their possible application for spin- flipping. By using an rf-solenoid magnet, we reached a 98.7 ± 1% efficiency of spin-flipping. However, an rf-dipole magnet is more practical at high energies; hence, studies of spin-flipping by an rf-dipole are underway at IUCF.

  2. 14N Nuclear Quadrupole Resonance Signals in Paranitrotoluene and Trinitrotoluene. Spin-Lock Spin-Echo Off-Resonance Effects

    Science.gov (United States)

    Gregorovič, Alan; Apih, Tomaž; Lužnik, Janko; Pirnat, Janez; Trontelj, Zvone

    A simple, yet effective technique to enhance the 14N NQR trinitrotoluene notoriously low sensitivity is the use of multipulse sequences. Here we investigate the off-resonance effects of the Spin-Lock Spin-Echo multipulse sequence, a predecessor of many advanced pulse sequences used for the same enhancement. Two samples have been used: paranitrotoluene, with a single 14N site as a model compound for trinitrotoluene, and trinitrotoluene itself, with six 14N sites. Our main focus has been the irradiation frequency dependence of the NQR signal, which is important when 14N NQR is used for remote detection of explosives. The two related principal issues are: the target temperature uncertainty and the existence of multiplets with several closely spaced resonance frequencies. The first applies to any explosive, since in remote detection the temperature is only approximately known, whereas the second applies mainly to trinitrotoluene, with 12 resonance frequencies between 837 and 871 kHz. Our frequency dependent investigation shows that the signal intensity as well as the effective spinspin relaxation time varies substantially with irradiation frequency in both samples. We provide a theoretical explanation of this variation which describes very well the observations and can be useful for increasing the reliability of remote detection signal processing.

  3. Resonant pinning spectroscopy with spin-vortex pairs

    Science.gov (United States)

    Holmgren, E.; Bondarenko, A.; Ivanov, B. A.; Korenivski, V.

    2018-03-01

    Vortex pairs in magnetic nanopillars with strongly coupled cores and pinning of one of the cores by a morphological defect, are used to perform resonant pinning spectroscopy, in which a microwave excitation applied to the nanopillar produces pinning or depinning of the cores only when the excitation is in resonance with the rotational or gyrational eigenmodes of the specific initial state of the core-core pair. The shift in the eigenmode frequencies between the pinned and depinned states is determined experimentally and explained theoretically, and illustrates the potential for multicore spin-vortex memory with resonant writing of information onto various stable vortex pair states. Further, it is shown how the same resonant spectroscopy techniques applied to a vortex pair can be used as a sensitive nanoscale probe for characterizing morphological defects in magnetic films.

  4. Resonant spin wave excitations in a magnonic crystal cavity

    Science.gov (United States)

    Kumar, N.; Prabhakar, A.

    2018-03-01

    Spin polarized electric current, injected into permalloy (Py) through a nano contact, exerts a torque on the magnetization. The spin waves (SWs) thus excited propagate radially outward. We propose an antidot magnonic crystal (MC) with a three-hole defect (L3) around the nano contact, designed so that the frequency of the excited SWs, lies in the band gap of the MC. L3 thus acts as a resonant SW cavity. The energy in this magnonic crystal cavity can be tapped by an adjacent MC waveguide (MCW). An analysis of the simulated micromagnetic power spectrum, at the output port of the MCW reveals stable SW oscillations. The quality factor of the device, calculated using the decay method, was estimated as Q > 105 for an injected spin current density of 7 ×1012 A/m2.

  5. Electron Spin Resonance Measurement with Microinductor on Chip

    Directory of Open Access Journals (Sweden)

    Akio Kitagawa

    2011-01-01

    Full Text Available The detection of radicals on a chip is demonstrated. The proposed method is based on electron spin resonance (ESR spectroscopy and the measurement of high-frequency impedance of the microinductor fabricated on the chip. The measurement was by using a frequency sweep of approximately 100 MHz. The ESR spectra of di(phenyl-(2,4,6-trinitrophenyliminoazanium (DPPH dropped on the microinductor which is fabricated with CMOS 350-nm technology were observed at room temperature. The volume of the DPPH ethanol solution was 2 μL, and the number of spins on the micro-inductor was estimated at about 1014. The sensitivity is not higher than that of the standard ESR spectrometers. However, the result indicates the feasibility of a near field radical sensor in which the microinductor as a probe head and ESR signal processing circuit are integrated.

  6. Simulations of Resonant Intraband and Interband Tunneling Spin Filters

    Science.gov (United States)

    Ting, David; Cartoixa-Soler, Xavier; McGill, T. C.; Smith, Darryl L.; Schulman, Joel N.

    2001-01-01

    This viewgraph presentation reviews resonant intraband and interband tunneling spin filters It explores the possibility of building a zero-magnetic-field spin polarizer using nonmagnetic III-V semiconductor heterostructures. It reviews the extensive simulations of quantum transport in asymmetric InAs/GaSb/AlSb resonant tunneling structures with Rashba spin splitting and proposes a. new device concept: side-gated asymmetric Resonant Interband Tunneling Diode (a-RITD).

  7. Spin resonance strength calculation through single particle tracking for RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States); Dutheil, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States); Huang, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ranjbar, V. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    The strengths of spin resonances for the polarized-proton operation in the Relativistic Heavy Ion Collider are currently calculated with the code DEPOL, which numerically integrates through the ring based on an analytical approximate formula. In this article, we test a new way to calculate the spin resonance strengths by performing Fourier transformation to the actual transverse magnetic fields seen by a single particle traveling through the ring. Comparison of calculated spin resonance strengths is made between this method and DEPOL.

  8. Resonant tunneling of spin-wave packets via quantized states in potential wells.

    Science.gov (United States)

    Hansen, Ulf-Hendrik; Gatzen, Marius; Demidov, Vladislav E; Demokritov, Sergej O

    2007-09-21

    We have studied the tunneling of spin-wave pulses through a system of two closely situated potential barriers. The barriers represent two areas of inhomogeneity of the static magnetic field, where the existence of spin waves is forbidden. We show that for certain values of the spin-wave frequency corresponding to the quantized spin-wave states existing in the well formed between the barriers, the tunneling has a resonant character. As a result, transmission of spin-wave packets through the double-barrier structure is much more efficient than the sequent tunneling through two single barriers.

  9. Resonance fluorescence and electron spin in semiconductor quantum dots

    International Nuclear Information System (INIS)

    Zhao, Yong

    2009-01-01

    The work presented in this dissertation contains the first observation of spin-resolved resonance fluorescence from a single quantum dot and its application of direct measurement of electron spin dynamics. The Mollow triplet and the Mollow quintuplet, which are the hallmarks of resonance fluorescence, are presented as the non-spin-resolved and spin-resolved resonance fluorescence spectrum, respectively. The negligible laser background contribution, the near pure radiative broadened spectrum and the anti-bunching photon statistics imply the sideband photons are background-free and near transform-limited single photons. This demonstration is a promising step towards the heralded single photon generation and electron spin readout. Instead of resolving spectrum, an alternative spin-readout scheme by counting resonance fluorescence photons under moderate laser power is demonstrated. The measurements of n-shot time-resolved resonance fluorescence readout are carried out to reveal electron spin dynamics of the measurement induced back action and the spin relaxation. Hyperfine interaction and heavy-light hole mixing are identified as the relevant mechanisms for the back action and phonon-assistant spin-orbit interaction dominates the spin relaxation. After a detailed discussion on charge-spin configurations in coupled quantum dots system, the single-shot readout on electron spin are proposed. (orig.)

  10. Resonance fluorescence and electron spin in semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yong

    2009-11-18

    The work presented in this dissertation contains the first observation of spin-resolved resonance fluorescence from a single quantum dot and its application of direct measurement of electron spin dynamics. The Mollow triplet and the Mollow quintuplet, which are the hallmarks of resonance fluorescence, are presented as the non-spin-resolved and spin-resolved resonance fluorescence spectrum, respectively. The negligible laser background contribution, the near pure radiative broadened spectrum and the anti-bunching photon statistics imply the sideband photons are background-free and near transform-limited single photons. This demonstration is a promising step towards the heralded single photon generation and electron spin readout. Instead of resolving spectrum, an alternative spin-readout scheme by counting resonance fluorescence photons under moderate laser power is demonstrated. The measurements of n-shot time-resolved resonance fluorescence readout are carried out to reveal electron spin dynamics of the measurement induced back action and the spin relaxation. Hyperfine interaction and heavy-light hole mixing are identified as the relevant mechanisms for the back action and phonon-assistant spin-orbit interaction dominates the spin relaxation. After a detailed discussion on charge-spin configurations in coupled quantum dots system, the single-shot readout on electron spin are proposed. (orig.)

  11. High-frequency EPR on high-spin transition-metal sites

    NARCIS (Netherlands)

    Mathies, Guinevere

    2012-01-01

    The electronic structure of transition-metal sites can be probed by electron-paramagnetic-resonance (EPR) spectroscopy. The study of high-spin transition-metal sites benefits from EPR spectroscopy at frequencies higher than the standard 9.5 GHz. However, high-frequency EPR is a developing field. In

  12. PREFACE: Muon spin rotation, relaxation or resonance

    Science.gov (United States)

    Heffner, Robert H.; Nagamine, Kanetada

    2004-10-01

    To a particle physicist a muon is a member of the lepton family, a heavy electron possessing a mass of about 1/9 that of a proton and a spin of 1/2, which interacts with surrounding atoms and molecules electromagnetically. Since its discovery in 1937, the muon has been put to many uses, from tests of special relativity to deep inelastic scattering, from studies of nuclei to tests of weak interactions and quantum electrodynamics, and most recently, as a radiographic tool to see inside heavy objects and volcanoes. In 1957 Richard Garwin and collaborators, while conducting experiments at the Columbia University cyclotron to search for parity violation, discovered that spin-polarized muons injected into materials might be useful to probe internal magnetic fields. This eventually gave birth to the modern field of muSR, which stands for muon spin rotation, relaxation or resonance, and is the subject of this special issue of Journal of Physics: Condensed Matter. Muons are produced in accelerators when high energy protons (generally >500 MeV) strike a target like graphite, producing pions which subsequently decay into muons. Most experiments carried out today use relatively low-energy (~4 MeV), positively-charged muons coming from pions decaying at rest in the skin of the production target. These muons have 100% spin polarization, a range in typical materials of about 180 mg cm-2, and are ideal for experiments in condensed matter physics and chemistry. Negatively-charged muons are also occasionally used to study such things as muonic atoms and muon-catalysed fusion. The muSR technique provides a local probe of internal magnetic fields and is highly complementary to inelastic neutron scattering and nuclear magnetic resonance, for example. There are four primary muSR facilities in the world today: ISIS (Didcot, UK), KEK (Tsukuba, Japan), PSI (Villigen, Switzerland) and TRIUMF (Vancouver, Canada), serving about 500 researchers world-wide. A new facility, JPARC (Tokai, Japan

  13. Pressure dependent resonant frequency of micromechanical drumhead resonators

    International Nuclear Information System (INIS)

    Southworth, D. R.; Craighead, H. G.; Parpia, J. M.

    2009-01-01

    We examine the relationship between squeeze film effects and resonance frequency in drum-type resonators. We find that the resonance frequency increases linearly with pressure as a result of the additional restoring force contribution from compression of gas within the drum cavity. We demonstrate trapping of the gas by squeeze film effects and geometry. The pressure sensitivity is shown to scale inversely with cavity height and sound radiation is found to be the predominant loss mechanism near and above atmospheric pressure. Drum resonators exhibit linearity and sensitivity suitable to barometry from below 10 Torr up to several atmospheres.

  14. Dynamic resonant frequency control of ultrasonic transducer for stabilizing resonant state in wide frequency band

    Science.gov (United States)

    Yokozawa, Hiroki; Twiefel, Jens; Weinstein, Michael; Morita, Takeshi

    2017-07-01

    Controlling the resonant frequency of ultrasonic transducers is important to achieve the excellent performance of ultrasonic devices. The resonant frequency can be shifted by a nonlinear effect or by increasing the temperature under high-power operation. We propose a resonant frequency control method during the transducer’s operation that enables the dynamic compensation of resonant frequency shifts. To realize this, a transducer with passive piezoelectric parts was fabricated. By controlling the electric boundary condition of the passive piezoelectric parts between short and open by utilizing a metal-oxide-semiconductor field-effect transistor (MOSFET), the stiffness was changed, thus modifying the resonant frequency. In both simulation and experiment, the resonant frequency was modified successfully by controlling the switching duty ratio of the MOSFET. Additionally, a system for exciting a transducer at a resonant state with a wide frequency band was demonstrated.

  15. Resolving spin-orbit- and hyperfine-mediated electric dipole spin resonance in a quantum dot.

    Science.gov (United States)

    Shafiei, M; Nowack, K C; Reichl, C; Wegscheider, W; Vandersypen, L M K

    2013-03-08

    We investigate the electric manipulation of a single-electron spin in a single gate-defined quantum dot. We observe that so-far neglected differences between the hyperfine- and spin-orbit-mediated electric dipole spin resonance conditions have important consequences at high magnetic fields. In experiments using adiabatic rapid passage to invert the electron spin, we observe an unusually wide and asymmetric response as a function of the magnetic field. Simulations support the interpretation of the line shape in terms of four different resonance conditions. These findings may lead to isotope-selective control of dynamic nuclear polarization in quantum dots.

  16. Optimal control of the inversion of two spins in Nuclear Magnetic Resonance

    International Nuclear Information System (INIS)

    Assémat, E.; Attar, L.; Penouilh, M.-J.; Picquet, M.; Tabard, A.; Zhang, Y.; Glaser, S.J.; Sugny, D.

    2012-01-01

    Highlights: ► We investigate the simultaneous optimal control of the inversion of two spins. ► We examine the energy minimum solution. ► We compare this solution with the time-minimum one. ► Experimental implementation using techniques of Nuclear Magnetic Resonance. -- Abstract: We investigate the optimal control of the inversion of two spin 1/2 particles in Nuclear Magnetic Resonance. The two spins, which differ by their resonance offset, are controlled by the same radio frequency magnetic field. Using the Pontryagin Maximum Principle, we compute the optimal control sequence which allows to reach the target state in a given time, while minimizing the energy of the magnetic field. A comparison with the time-optimal solution for bounded control amplitude realizing the same control in the same time is made. An experimental illustration is done using techniques of Nuclear Magnetic Resonance.

  17. Spin microscope based on optically detected magnetic resonance

    Science.gov (United States)

    Berman, Gennady P.; Chernobrod, Boris M.

    2007-12-11

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  18. Continuous wave protocol for simultaneous polarization and optical detection of P1-center electron spin resonance

    Science.gov (United States)

    Kamp, E. J.; Carvajal, B.; Samarth, N.

    2018-01-01

    The ready optical detection and manipulation of bright nitrogen vacancy center spins in diamond plays a key role in contemporary quantum information science and quantum metrology. Other optically dark defects such as substitutional nitrogen atoms (`P1 centers') could also become potentially useful in this context if they could be as easily optically detected and manipulated. We develop a relatively straightforward continuous wave protocol that takes advantage of the dipolar coupling between nitrogen vacancy and P1 centers in type 1b diamond to detect and polarize the dark P1 spins. By combining mutual spin flip transitions with radio frequency driving, we demonstrate the simultaneous optical polarization and detection of the electron spin resonance of the P1 center. This technique should be applicable to detecting and manipulating a broad range of dark spin populations that couple to the nitrogen vacancy center via dipolar fields, allowing for quantum metrology using these spin populations.

  19. Spin relaxation mechanism in graphene: resonant scattering by magnetic impurities.

    Science.gov (United States)

    Kochan, Denis; Gmitra, Martin; Fabian, Jaroslav

    2014-03-21

    We propose that the observed small (100 ps) spin relaxation time in graphene is due to resonant scattering by local magnetic moments. At resonances, magnetic moments behave as spin hot spots: the spin-flip scattering rates are as large as the spin-conserving ones, as long as the exchange interaction is greater than the resonance width. Smearing of the resonance peaks by the presence of electron-hole puddles gives quantitative agreement with experiment, for about 1 ppm of local moments. Although magnetic moments can come from a variety of sources, we specifically consider hydrogen adatoms, which are also resonant scatterers. The same mechanism would also work in the presence of a strong local spin-orbit interaction, but this would require heavy adatoms on graphene or a much greater coverage density of light adatoms. To make our mechanism more transparent, we also introduce toy atomic chain models for resonant scattering of electrons in the presence of a local magnetic moment and Rashba spin-orbit interaction.

  20. Phonon-magnon resonant processes with relevance to acoustic spin pumping

    KAUST Repository

    Deymier, P. A.

    2014-12-23

    The recently described phenomenon of resonant acoustic spin pumping is due to resonant coupling between an incident elastic wave and spin waves in a ferromagnetic medium. A classical one-dimensional discrete model of a ferromagnet with two forms of magnetoelastic coupling is treated to shed light on the conditions for resonance between phonons and magnons. Nonlinear phonon-magnon interactions in the case of a coupling restricted to diagonal terms in the components of the spin degrees of freedom are analyzed within the framework of the multiple timescale perturbation theory. In that case, one-phonon-two-magnon resonances are the dominant mechanism for pumping. The effect of coupling on the dispersion relations depends on the square of the amplitude of the phonon and magnon excitations. A straightforward analysis of a linear phonon-magnon interaction in the case of a magnetoelastic coupling restricted to off-diagonal terms in the components of the spins shows a one-phonon to one-magnon resonance as the pumping mechanism. The resonant dispersion relations are independent of the amplitude of the waves. In both cases, when an elastic wave with a fixed frequency is used to stimulate magnons, application of an external magnetic field can be used to approach resonant conditions. Both resonance conditions exhibit the same type of dependency on the strength of an applied magnetic field.

  1. Effects of off-resonance spins on the performance of the modulated gradient spin echo sequence

    Science.gov (United States)

    Serša, Igor; Bajd, Franci; Mohorič, Aleš

    2016-09-01

    Translational molecular dynamics in various materials can also be studied by diffusion spectra. These can be measured by a constant gradient variant of the modulated gradient spin echo (MGSE) sequence which is composed of a CPMG RF pulse train superimposed to a constant magnetic field gradient. The application of the RF train makes the effective gradient oscillating thus enabling measurements of diffusion spectra in a wide range of frequencies. However, seemingly straightforward implementation of the MGSE sequence proved to be complicated and can give overestimated results for diffusion if not interpreted correctly. In this study, unrestricted diffusion in water and other characteristic materials was analyzed by the MGSE sequence in the frequency range 50-3000 Hz using a 6 T/m diffusion probe. First, it was shown that the MGSE echo train acquired from the entire sample decays faster than the train acquired only from a narrow band at zero frequency of the sample. Then, it was shown that the decay rate is dependent on the band's off-resonance characterized by the ratio Δω0 /ω1 and that with higher off-resonances the decay is faster. The faster decay therefore corresponds to a higher diffusion coefficient if the diffusion is calculated using standard Stejskal-Tanner formula. The result can be explained by complex coherence pathways contributing to the MGSE echo signals when | Δω0 | /ω1 > 0 . In a magnetic field gradient, all the pathways are more diffusion attenuated than the direct coherence pathway and therefore decay faster, which leads to an overestimation of the diffusion coefficient. A solution to this problem was found in an efficient off-resonance signal reduction by using only zero frequency filtered MGSE echo train signals.

  2. Probing quantum coherence in single-atom electron spin resonance

    Science.gov (United States)

    Willke, Philip; Paul, William; Natterer, Fabian D.; Yang, Kai; Bae, Yujeong; Choi, Taeyoung; Fernández-Rossier, Joaquin; Heinrich, Andreas J.; Lutz, Christoper P.

    2018-01-01

    Spin resonance of individual spin centers allows applications ranging from quantum information technology to atomic-scale magnetometry. To protect the quantum properties of a spin, control over its local environment, including energy relaxation and decoherence processes, is crucial. However, in most existing architectures, the environment remains fixed by the crystal structure and electrical contacts. Recently, spin-polarized scanning tunneling microscopy (STM), in combination with electron spin resonance (ESR), allowed the study of single adatoms and inter-atomic coupling with an unprecedented combination of spatial and energy resolution. We elucidate and control the interplay of an Fe single spin with its atomic-scale environment by precisely tuning the phase coherence time T2 using the STM tip as a variable electrode. We find that the decoherence rate is the sum of two main contributions. The first scales linearly with tunnel current and shows that, on average, every tunneling electron causes one dephasing event. The second, effective even without current, arises from thermally activated spin-flip processes of tip spins. Understanding these interactions allows us to maximize T2 and improve the energy resolution. It also allows us to maximize the amplitude of the ESR signal, which supports measurements even at elevated temperatures as high as 4 K. Thus, ESR-STM allows control of quantum coherence in individual, electrically accessible spins. PMID:29464211

  3. Probing quantum coherence in single-atom electron spin resonance.

    Science.gov (United States)

    Willke, Philip; Paul, William; Natterer, Fabian D; Yang, Kai; Bae, Yujeong; Choi, Taeyoung; Fernández-Rossier, Joaquin; Heinrich, Andreas J; Lutz, Christoper P

    2018-02-01

    Spin resonance of individual spin centers allows applications ranging from quantum information technology to atomic-scale magnetometry. To protect the quantum properties of a spin, control over its local environment, including energy relaxation and decoherence processes, is crucial. However, in most existing architectures, the environment remains fixed by the crystal structure and electrical contacts. Recently, spin-polarized scanning tunneling microscopy (STM), in combination with electron spin resonance (ESR), allowed the study of single adatoms and inter-atomic coupling with an unprecedented combination of spatial and energy resolution. We elucidate and control the interplay of an Fe single spin with its atomic-scale environment by precisely tuning the phase coherence time T 2 using the STM tip as a variable electrode. We find that the decoherence rate is the sum of two main contributions. The first scales linearly with tunnel current and shows that, on average, every tunneling electron causes one dephasing event. The second, effective even without current, arises from thermally activated spin-flip processes of tip spins. Understanding these interactions allows us to maximize T 2 and improve the energy resolution. It also allows us to maximize the amplitude of the ESR signal, which supports measurements even at elevated temperatures as high as 4 K. Thus, ESR-STM allows control of quantum coherence in individual, electrically accessible spins.

  4. Low-frequency nuclear quadrupole resonance with a dc SQUID

    Energy Technology Data Exchange (ETDEWEB)

    Chang, J.W.

    1991-07-01

    Conventional pure nuclear quadrupole resonance (NQR) is a technique well suited for the study of very large quadrupolar interactions. Numerous nuclear magnetic resonance (NMR) techniques have been developed for the study of smaller quadrupolar interactions. However, there are many nuclei which have quadrupolar interactions of intermediate strength. Quadrupolar interactions in this region have traditionally been difficult or unfeasible to detect. This work describes the development and application of a SQUID NQR technique which is capable of measuring intermediate strength quadrupolar interactions, in the range of a few hundred kilohertz to several megahertz. In this technique, a dc SQUID (Superconducting QUantum Interference Device) is used to monitor the longitudinal sample magnetization, as opposed to the transverse magnetization, as a rf field is swept in frequency. This allows the detection of low-frequency nuclear quadrupole resonances over a very wide frequency range with high sensitivity. The theory of this NQR technique is discussed and a description of the dc SQUID system is given. In the following chapters, the spectrometer is discussed along with its application to the study of samples containing half-odd-integer spin quadrupolar nuclei, in particular boron-11 and aluminum-27. The feasibility of applying this NQR technique in the study of samples containing integer spin nuclei is discussed in the last chapter. 140 refs., 46 figs., 6 tabs.

  5. Electron spin resonance and spin-valley physics in a silicon double quantum dot.

    Science.gov (United States)

    Hao, Xiaojie; Ruskov, Rusko; Xiao, Ming; Tahan, Charles; Jiang, HongWen

    2014-05-14

    Silicon quantum dots are a leading approach for solid-state quantum bits. However, developing this technology is complicated by the multi-valley nature of silicon. Here we observe transport of individual electrons in a silicon CMOS-based double quantum dot under electron spin resonance. An anticrossing of the driven dot energy levels is observed when the Zeeman and valley splittings coincide. A detected anticrossing splitting of 60 MHz is interpreted as a direct measure of spin and valley mixing, facilitated by spin-orbit interaction in the presence of non-ideal interfaces. A lower bound of spin dephasing time of 63 ns is extracted. We also describe a possible experimental evidence of an unconventional spin-valley blockade, despite the assumption of non-ideal interfaces. This understanding of silicon spin-valley physics should enable better control and read-out techniques for the spin qubits in an all CMOS silicon approach.

  6. High frequency spin torque oscillators with composite free layer spin valve

    International Nuclear Information System (INIS)

    Natarajan, Kanimozhi; Arumugam, Brinda; Rajamani, Amuda

    2016-01-01

    We report the oscillations of magnetic spin components in a composite free layer spin valve. The associated Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation is studied by stereographically projecting the spin on to a complex plane and the spin components were found. A fourth order Runge–Kutta numerical integration on LLGS equation also confirms the similar trajectories of the spin components. This study establishes the possibility of a Spin Torque Oscillator in a composite free layer spin valve, where the exchange coupling is ferromagnetic in nature. In-plane and out-of-plane precessional modes of magnetization oscillations were found in zero applied magnetic field and the frequencies of the oscillations were calculated from Fast Fourier Transform of the components of magnetization. Behavior of Power Spectral Density for a range of current density is studied. Finally our analysis shows the occurrence of highest frequency 150 GHz, which is in the second harmonics for the specific choice of system parameters.

  7. Study of spin resonances in the accelerators with snakes

    International Nuclear Information System (INIS)

    Lee, S.Y.

    1989-01-01

    Spin resonances in the circular accelerators with snakes are studied to understand the nature of snake resonances. We analyze the effect of snake configuration, and the snake superperiod on the resonance. Defining the critical resonance strength ε c as the maximum tolerable resonance strength without losing the beam polarization after passing through the resonance, we found that ε c is a sensitive function of the snake configuration, the snake superperiod at the first order snake resonance, the higher order snake resonance conditions and the spin matching condition. Under properly designed snake configuration, the critical resonance strength ε c is found to vary linearly with N S as left-angle ε c right-angle=(1/π)sin -1 (cos πν z | 1/2 )N S , where ν| z and N S are the betatron tune and the number of snakes respectively. We also study the effect of overlapping intrinsic and imperfection resonances. The imperfection resonance should be corrected to a magnitude of insignificance (e.g., ε≤0.1 for two snakes case) to maintain proper polarization

  8. Study of spin resonances in the accelerators with snakes

    International Nuclear Information System (INIS)

    Lee, S.Y.

    1988-01-01

    Spin resonances in the circular accelerators with snakes are studied to understand the nature of snake resonances. We analyze the effect of snake configuration, and the snake superperiod on the resonance. Defining the critical resonance strength ε/sub c/ as the maximum tolerable resonance strength without losing the beam polarization after passing through the resonance, we found that ε/sub c/ is a sensitive function of the snake configuration, the snake superperiod at the first order snake resonance, the higher order snake resonance conditions and the spin matching condition. Under properly designed snake configuration, the critical resonance strength ε/sub c/ is found to vary linearly with N/sub S/ as = (1/π)sin/sup /minus/1/(cos πν/sub z//sup /1/2//)N/sub S/, where ν/sub z/ and N/sub S/ are the betatron tune and the number of snakes respectively. We also study the effect of overlapping intrinsic and imperfection resonances. The imperfection resonance should be corrected to a magnitude of insignificance (e.g., ε≤0.1 for two snakes case) to maintain proper polarization. 23 refs., 25 figs

  9. On Frequency Combs in Monolithic Resonators

    Directory of Open Access Journals (Sweden)

    Savchenkov A. A.

    2016-06-01

    Full Text Available Optical frequency combs have become indispensable in astronomical measurements, biological fingerprinting, optical metrology, and radio frequency photonic signal generation. Recently demonstrated microring resonator-based Kerr frequency combs point the way towards chip scale optical frequency comb generator retaining major properties of the lab scale devices. This technique is promising for integrated miniature radiofrequency and microwave sources, atomic clocks, optical references and femtosecond pulse generators. Here we present Kerr frequency comb development in a historical perspective emphasizing its similarities and differences with other physical phenomena. We elucidate fundamental principles and describe practical implementations of Kerr comb oscillators, highlighting associated solved and unsolved problems.

  10. Storage ring lattice calibration using resonant spin depolarization

    Directory of Open Access Journals (Sweden)

    K. P. Wootton

    2013-07-01

    Full Text Available This paper presents measurements of the GeV-scale electron beam energy for the storage rings at the synchrotron light source facilities Australian Synchrotron (AS and SPEAR3 at SLAC. Resonant spin depolarization was employed in the beam energy measurement, since it is presently the highest precision technique and an uncertainty of order 10^{-6} was achieved at SPEAR3 and AS. Using the resonant depolarization technique, the beam energy was measured at various rf frequencies to measure the linear momentum compaction factor. This measured linear momentum compaction factor was used to evaluate models of the beam trajectory through combined-function bending magnets. The main bending magnets of both lattices are rectangular, horizontally defocusing gradient bending magnets. Four modeling approaches are compared for the beam trajectory through the bending magnet: a circular trajectory, linear and nonlinear hyperbolic cosine trajectories, and numerical evaluation of the trajectory through the measured magnetic field map. Within the uncertainty of the measurement the momentum compaction factor is shown to agree with the numerical model of the trajectory within the bending magnet, and disagree with the hyperbolic cosine approximation.

  11. The influence of interlayer exchange coupling in giant-magnetoresistive devices on spin diode effect in wide frequency range

    Energy Technology Data Exchange (ETDEWEB)

    Ziętek, Sławomir, E-mail: zietek@agh.edu.pl; Skowroński, Witold; Wiśniowski, Piotr; Czapkiewicz, Maciej; Stobiecki, Tomasz [Department of Electronics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków (Poland); Ogrodnik, Piotr [Department of Electronics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków (Poland); Faculty of Physics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warszawa (Poland); Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań (Poland); Barnaś, Józef [Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań (Poland); Faculty of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland)

    2015-09-21

    Spin diode effect in a giant magnetoresistive strip is measured in a broad frequency range, including resonance and off-resonance frequencies. The off-resonance dc signal is relatively strong and also significantly dependent on the exchange coupling between magnetic films through the spacer layer. The measured dc signal is described theoretically by taking into account magnetic dynamics induced by Oersted field created by an ac current flowing through the system.

  12. Rod Driven Frequency Entrainment and Resonance Phenomena

    Directory of Open Access Journals (Sweden)

    Christina Salchow

    2016-08-01

    Full Text Available A controversy exists on photic driving in the human visual cortex evoked by intermittent photic stimulation. Frequency entrainment and resonance phenomena are reported for frequencies higher than 12 Hz in some studies while missing in others. We hypothesized that this might be due to different experimental conditions, since both high and low intensity light stimulation were used. However, most studies do not report radiometric measurements, which makes it impossible to categorize the stimulation according to photopic, mesopic, and scotopic vision. Low intensity light stimulation might lead to scotopic vision, where rod perception dominates. In this study, we investigated photic driving for rod-dominated visual input under scotopic conditions. Twelve healthy volunteers were stimulated with low intensity light flashes at 20 stimulation frequencies, leading to rod activation only. The frequencies were multiples of the individual alpha frequency (α of each volunteer in the range from 0.40–2.30*α. 306-channel whole head magnetoencephalography recordings were analyzed in time, frequency, and spatiotemporal domains with the Topographic Matching Pursuit algorithm. We found resonance phenomena and frequency entrainment for stimulations at or close to the individual alpha frequency (0.90–1.10*α and half of the alpha frequency (0.40–0.55*α. No signs of resonance and frequency entrainment phenomena were revealed around 2.00*α. Instead, on-responses at the beginning and off-responses at the end of each stimulation train were observed for the first time in a photic driving experiment at frequencies of 1.30–2.30*α, indicating that the flicker fusion threshold was reached. All results, the resonance and entrainment as well as the fusion effects, provide evidence for rod-dominated photic driving in the visual cortex.

  13. Gravitational Waves and the Maximum Spin Frequency of Neutron Stars

    NARCIS (Netherlands)

    Patruno, A.; Haskell, B.; D'Angelo, C.

    2012-01-01

    In this paper, we re-examine the idea that gravitational waves are required as a braking mechanism to explain the observed maximum spin frequency of neutron stars. We show that for millisecond X-ray pulsars, the existence of spin equilibrium as set by the disk/magnetosphere interaction is sufficient

  14. Spin coupling resonance and suppression in the AGS

    Directory of Open Access Journals (Sweden)

    V. H. Ranjbar

    2004-05-01

    Full Text Available A spin matching method to cure intrinsic coupled spin resonances in the AGS is proposed and explored using an extension of the existing DEPOL program algorithm. The extension of DEPOL to handle linear coupling in the polarized beam acceleration is documented. Data collected from recent polarized proton experiments in the AGS are compared with the predictions derived from the extended DEPOL program.

  15. Characterization of perpendicular STT-MRAM by spin torque ferromagnetic resonance

    Science.gov (United States)

    Sha, Chengcen; Yang, Liu; Lee, Han Kyu; Barsukov, Igor; Zhang, Jieyi; Krivorotov, Ilya

    We describe a method for simple quantitative measurement of magnetic anisotropy and Gilbert damping of the MTJ free layer in individual perpendicular STT-MRAM devices by spin torque ferromagnetic resonance (ST-FMR) with magnetic field modulation. We first show the dependence of ST-FMR spectra of an STT-MRAM element on out-of-plane magnetic field. In these spectra, resonances arising from excitation of the quasi-uniform and higher order spin wave eigenmodes of the free layer as well as acoustic mode of the synthetic antiferromagnet (SAF) are clearly seen. The quasi-uniform mode frequency at zero field gives magnetic anisotropy field of the free layer. Then we show dependence of the quasi-uniform mode linewidth on frequency is linear over a range of frequencies but deviatesfrom linearity in the low and high frequency regimes. Comparison to ST-FMR spectrareveals that the high frequency line broadening is linked to the SAF mode softening near the SAF spin flop transition at 5 kG. In the low field regime, the SAF mode frequency approaches that of the quasi-uniform mode, and resonant coupling of the modes leads to the line broadening. A linear fit to the linewidth data outside of the high and low field regimes gives the Gilbert damping parameter of the free layer. This work was supported by the Samsung Global MRAM Innovation Program.

  16. Development of Millimeter Wave Fabry-Pérot Resonator for Simultaneous Electron-Spin and Nuclear Magnetic Resonance Measurement

    Science.gov (United States)

    Ishikawa, Yuya; Ohya, Kenta; Fujii, Yutaka; Fukuda, Akira; Miura, Shunsuke; Mitsudo, Seitaro; Yamamori, Hidetomo; Kikuchi, Hikomitsu

    2018-04-01

    We report a Fabry-Pérot resonator with spherical and flat mirrors to allow simultaneous electron-spin resonance (ESR) and nuclear magnetic resonance (NMR) measurements that could be used for double magnetic resonance (DoMR). In order to perform simultaneous ESR and NMR measurements, the flat mirror must reflect millimeter wavelength electromagnetic waves and the resonator must have a high Q value ( Q > 3000) for ESR frequencies, while the mirror must simultaneously let NMR frequencies pass through. This requirement can be achieved by exploiting the difference of skin depth for the two frequencies, since skin depth is inversely proportional to the square root of the frequency. In consideration of the skin depth, the optimum conditions for conducting ESR and NMR using a gold thin film are explored by examining the relation between the Q value and the film thickness. A flat mirror with a gold thin film was fabricated by sputtering gold on an epoxy plate. We also installed a Helmholtz radio frequency coil for NMR and tested the system both at room and low temperatures with an optimally thick gold film. As a result, signals were obtained at 0.18 K for ESR and at 1.3 K for NMR. A flat-mirrored resonator with a thin gold film surface is an effective way to locate NMR coils closer to the sample being examined with DoMR.

  17. Coherent Control of a Nitrogen-Vacancy Center Spin Ensemble with a Diamond Mechanical Resonator

    Science.gov (United States)

    Guo, F.; Macquarrie, E. R.; Gosavi, T. A.; Moehle, A. M.; Jungwirth, N. R.; Bhave, S. A.; Fuchs, G. D.

    2015-03-01

    In contrast to the traditional coherent control of the nitrogen vacancy (NV) center in diamond's triplet spin state with ac magnetic fields, we recently demonstrated that gigahertz-frequency lattice strain resonant with the ms= +1 to -1 spin state splitting can also be used to drive spin transitions. We present coherent spin control over NV center ensembles with a bulk-mode mechanical microresonator that generates large amplitude ac stress within the diamond substrate. Using these structures, we mechanically drive coherent Rabi oscillations between the -1 and +1 states. We also accurately model the Rabi dephasing with a combination of a spatially inhomogeneous mechanical driving field and magnetic noise from a fluctuating spin bath. Understanding mechanically driven dynamics in spin ensembles could have applications in sensing and quantum optomechanics where interactions can be enhanced by the number of spins. Moreover, these results demonstrate coherent mechanical control of the magnetically forbidden -1 to +1 spin transition, thus closing the loop on NV center ground state spin control and enabling the creation of a coherent Δ-system within the NV center ground state. We gratefully acknowledge support from the ONR.

  18. Beam divergence correction method for neutron resonance spin echo spectroscope

    International Nuclear Information System (INIS)

    Maruyama, Ryuji; Tasaki, Seiji; Hino, Masahiro; Kitaguchi, Masaaki; Kawabata, Yuji; Ebisawa, Toru

    2005-01-01

    A beam divergence correction method for Neutron resonance spin echo (NRSE) spectroscope was proposed and the effectiveness is evaluated by simulation. When a beam divergence correction coil was introduced into NRSE spectroscope and the optimum magnetic field was given, the visibility of spin echo signal was recovered by controlling scattering of phase difference generated by beam divergence. The effectiveness of the correction method was proved by the above result. Principle of NRSE spectroscopy, decrease of spin polarization rate by beam divergence and its correction method, structure of divergence angle correction coil and the magnetic field calculation and result of simulation are described. (S.Y.)

  19. Searching for new spin-0 resonances at LHCb

    CERN Document Server

    Haisch, Ulrich

    2016-01-01

    We study the phenomenology of light spin-0 particles and stress that they can be efficiently searched for at the LHCb experiment in the form of dimuon resonances. Given the large production cross sections in the forward rapidity region together with the efficient triggering and excellent mass resolution, it is argued that LHCb can provide unique sensitivity to such states. We illustrate our proposal using the recent measurement of Upsilon production by LHCb, emphasising the importance of mixing effects in the bottomonium resonance region. The implications for dimuon decays of spin-0 bottomonium states are also briefly discussed.

  20. Magnetic Resonance Imaging: From Spin Physics to Medical Diagnosis

    Science.gov (United States)

    Nacher, Pierre-Jean

    Two rather similar historical evolutions are evoked, each one originating in fundamental spin studies by physicists, and ending as magnetic resonance imaging (MRI), a set of invaluable tools for clinical diagnosis in the hands of medical doctors. The first one starts with the early work on nuclear magnetic resonance, the founding stone of the usual proton-based MRI, of which the basic principles are described. The second one starts with the optical pumping developments made to study the effects of spin polarization in various fundamental problems. Its unexpected outcome is a unique imaging modality, also based on MRI, for the study of lung physiology and pathologies.

  1. Antiferromagnetic ordering in spin-chain multiferroic Gd{sub 2}BaNiO{sub 5} studied by electronic spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y. M.; Ruan, M. Y.; Cheng, J. J.; Sun, Y. C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Ouyang, Z. W., E-mail: zwouyang@mail.hust.edu.cn; Xia, Z. C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Rao, G. H. [School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China)

    2015-06-14

    High-field electron spin resonance (ESR) has been employed to study the antiferromagnetic (AFM) ordering state (T < T{sub N} = 55 K) of spin-chain multiferroic Gd{sub 2}BaNiO{sub 5}. The spin reorientation at T{sub SR} = 24 K is well characterized by the temperature-dependent ESR spectra. The magnetization data evidence a field-induced spin-flop transition at 2 K. The frequency-field relationship of the ESR data can be explained by conventional AFM resonance theory with uniaxial anisotropy, in good agreement with magnetization data. Related discussion on zero-field spin gap is presented.

  2. Fluid dynamics of giant resonances on high spin states

    International Nuclear Information System (INIS)

    Di Nardo, M.; Di Toro, M.; Giansiracusa, G.; Lombardo, U.; Russo, G.

    1983-01-01

    We describe giant resonances built on high spin states along the yrast line as scaling solutions of a linearized Vlasov equation in a rotating frame obtained from a TDHF theory in phase space. For oblate cranked solutions we get a shift and a splitting of the isoscalar giant resonances in terms of the angular velocity. Results are shown for 40 Ca and 168 Er. The relative CM strengths are also calculated. (orig.)

  3. Electron spin resonance studies on reduction process of nitroxyl spin radicals used in molecular imaging

    Energy Technology Data Exchange (ETDEWEB)

    Dhas, M. Kumara; Benial, A. Milton Franklin, E-mail: miltonfranklin@yahoo.com [Department of Physics, NMSSVN College, Nagamalai, Madurai-625019, Tamilnadu (India); Jawahar, A. [Department of Chemistry, NMSSVN College, Nagamalai, Madurai-625019, Tamilnadu (India)

    2014-04-24

    The Electron spin resonance studies on the reduction process of nitroxyl spin probes were carried out for 1mM {sup 14}N labeled nitroxyl radicals in pure water and 1 mM concentration of ascorbic acid as a function of time. The electron spin resonance parameters such as signal intensity ratio, line width, g-value, hyperfine coupling constant and rotational correlation time were determined. The half life time was estimated for 1mM {sup 14}N labeled nitroxyl radicals in 1 mM concentration of ascorbic acid. The ESR study reveals that the TEMPONE has narrowest line width and fast tumbling motion compared with TEMPO and TEMPOL. From the results, TEMPONE has long half life time and high stability compared with TEMPO and TEMPOL radical. Therefore, this study reveals that the TEMPONE radical can act as a good redox sensitive spin probe for molecular imaging.

  4. Electron spin resonance studies on reduction process of nitroxyl spin radicals used in molecular imaging

    Science.gov (United States)

    Dhas, M. Kumara; Jawahar, A.; Benial, A. Milton Franklin

    2014-04-01

    The Electron spin resonance studies on the reduction process of nitroxyl spin probes were carried out for 1mM 14N labeled nitroxyl radicals in pure water and 1 mM concentration of ascorbic acid as a function of time. The electron spin resonance parameters such as signal intensity ratio, line width, g-value, hyperfine coupling constant and rotational correlation time were determined. The half life time was estimated for 1mM 14N labeled nitroxyl radicals in 1 mM concentration of ascorbic acid. The ESR study reveals that the TEMPONE has narrowest line width and fast tumbling motion compared with TEMPO and TEMPOL. From the results, TEMPONE has long half life time and high stability compared with TEMPO and TEMPOL radical. Therefore, this study reveals that the TEMPONE radical can act as a good redox sensitive spin probe for molecular imaging.

  5. Coherent Two-Dimensional Terahertz Magnetic Resonance Spectroscopy of Collective Spin Waves.

    Science.gov (United States)

    Lu, Jian; Li, Xian; Hwang, Harold Y; Ofori-Okai, Benjamin K; Kurihara, Takayuki; Suemoto, Tohru; Nelson, Keith A

    2017-05-19

    We report a demonstration of two-dimensional (2D) terahertz (THz) magnetic resonance spectroscopy using the magnetic fields of two time-delayed THz pulses. We apply the methodology to directly reveal the nonlinear responses of collective spin waves (magnons) in a canted antiferromagnetic crystal. The 2D THz spectra show all of the third-order nonlinear magnon signals including magnon spin echoes, and 2-quantum signals that reveal pairwise correlations between magnons at the Brillouin zone center. We also observe second-order nonlinear magnon signals showing resonance-enhanced second-harmonic and difference-frequency generation. Numerical simulations of the spin dynamics reproduce all of the spectral features in excellent agreement with the experimental 2D THz spectra.

  6. Accurate 3He polarimetry using the Rb Zeeman frequency shift due to the Rb-3He spin-exchange collisions

    International Nuclear Information System (INIS)

    Romalis, M.V.; Cates, G.D.

    1998-01-01

    We describe a method of 3 He polarimetry relying on the polarization-dependent frequency shift of the Rb Zeeman resonance. Our method is ideally suited for on-line measurements of the 3 He polarization produced by spin-exchange optical pumping. To calibrate the frequency shift we performed an accurate measurement of the imaginary part of the Rb- 3 He spin-exchange cross section in the temperature range typical for spin-exchange optical pumping of 3 He. We also present a detailed study of possible systematic errors in the frequency shift polarimetry. copyright 1998 The American Physical Society

  7. Selectivity of alkyl radical formation from branched alkanes studied by electron spin resonance and electron spin echo spectroscopy

    International Nuclear Information System (INIS)

    Tsuneki, Ichikawa; Hiroshi, Yoshida

    1992-01-01

    Alkyl radicals generated from branched alkanes by γ radiation are being measuring by electron spin resonance and electron spin echo spectroscopy. This research is being conducted to determine the mechanism of selective alkyl radical formation in low-temperature solids

  8. Electron spin resonance dating of fault gouge from Desamangalam

    Indian Academy of Sciences (India)

    The preliminary results from the electron spin resonance (ESR) dating on the quartz grains from the fault gouge indicate that the last major faulting in this site occurred 430 ± 43 ka ago. The experiments on different grain sizes of quartz from the gouge showed consistent decrease in age to a plateau of low values, indicating ...

  9. Magnetic defects in chemically converted graphene nanoribbons: electron spin resonance investigation

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao Singamaneni

    2014-04-01

    Full Text Available Electronic spin transport properties of graphene nanoribbons (GNRs are influenced by the presence of adatoms, adsorbates and edge functionalization. To improve the understanding of the factors that influence the spin properties of GNRs, local (element spin-sensitive techniques such as electron spin resonance (ESR spectroscopy are important for spintronics applications. Here, we present results of multi-frequency continuous wave (CW, pulse and hyperfine sublevel correlation (HYSCORE ESR spectroscopy measurements performed on oxidatively unzipped graphene nanoribbons (GNRs, which were subsequently chemically converted (CCGNRs with hydrazine. ESR spectra at 336 GHz reveal an isotropic ESR signal from the CCGNRs, of which the temperature dependence of its line width indicates the presence of localized unpaired electronic states. Upon functionalization of CCGNRs with 4-nitrobenzene diazonium tetrafluoroborate, the ESR signal is found to be 2 times narrower than that of pristine ribbons. NH3 adsorption/desorption on CCGNRs is shown to narrow the signal, while retaining the signal intensity and g value. The electron spin-spin relaxation process at 10 K is found to be characterized by slow (163 ns and fast (39 ns components. HYSCORE ESR data demonstrate the explicit presence of protons and 13C atoms. With the provided identification of intrinsic point magnetic defects such as proton and 13C has been reported, which are roadblocks to spin travel in graphene-based materials, this work could help in advancing the present fundamental understanding on the edge-spin (or magnetic-based transport properties of CCGNRs.

  10. Spin isovector giant resonances in (n,p) reactions

    Energy Technology Data Exchange (ETDEWEB)

    Spicer, B.M.

    1997-12-31

    The present status of the study of spin-flip isovector giant resonances, using the (n,p) charge exchange reaction, is reviewed. After a brief history of the discovery of these giant resonances, a critical appraisal of the interpretation of the data in terms of giant resonances is given, along with some of the theoretical advances that impact on the interpretation of these data. A sampling of the results obtained for typical targets is given, followed by the interpretation of these results. A brief statement is made concerning the way forward in experimental technique for nuclear structure research using charge exchange reactions. 54 refs., 18 figs.

  11. Spin isovector giant resonances in (n,p) reactions

    International Nuclear Information System (INIS)

    Spicer, B.M.

    1997-01-01

    The present status of the study of spin-flip isovector giant resonances, using the (n,p) charge exchange reaction, is reviewed. After a brief history of the discovery of these giant resonances, a critical appraisal of the interpretation of the data in terms of giant resonances is given, along with some of the theoretical advances that impact on the interpretation of these data. A sampling of the results obtained for typical targets is given, followed by the interpretation of these results. A brief statement is made concerning the way forward in experimental technique for nuclear structure research using charge exchange reactions

  12. Resonantly driven CNOT gate for electron spins

    Science.gov (United States)

    Zajac, D. M.; Sigillito, A. J.; Russ, M.; Borjans, F.; Taylor, J. M.; Burkard, G.; Petta, J. R.

    2018-01-01

    To build a universal quantum computer—the kind that can handle any computational task you throw at it—an essential early step is to demonstrate the so-called CNOT gate, which acts on two qubits. Zajac et al. built an efficient CNOT gate by using electron spin qubits in silicon quantum dots, an implementation that is especially appealing because of its compatibility with existing semiconductor-based electronics (see the Perspective by Schreiber and Bluhm). To showcase the potential, the authors used the gate to create an entangled quantum state called the Bell state.

  13. Spin noise spectroscopy from acoustic to GHz frequencies

    Science.gov (United States)

    Hübner, Jens

    2010-03-01

    Performing perturbation free measurements on semiconductor quantum systems has long been banished to textbooks on quantum mechanics. The emergent technique of spin noise spectroscopy is challenging this restriction. Empowered only by the ever present intrinsic spin fluctuation dynamics in thermal equilibrium, spin noise spectroscopy is capable to directly deduce several physical properties of carriers spins in semiconductors from these fluctuations. Originating from spin noise measurements on alkali metal vapors in quantum optics [1] the method has become a powerful technique to unravel the intrinsic spin dynamics in semiconductors [2]. In this talk I will present the recent progress of spin noise spectroscopy and how it is used to monitor the spin dynamic in semiconductor quantum wells at thermal equilibrium and as a consequence thereof directly detect the spatial dynamics of the carriers being marked with their own spin on a microscopic scale [3]. Further I will present measurements of how the non-perturbative nature of spin noise spectroscopy gives valuable insight into the delicate dependence of the spin relaxation time of electrons on doping density and temperature in semiconductors n-doped in the vicinity of the metal-insulator transition where hyperfine and intra-band depolarization compete [4]. Also the measurement bandwidth can be extended to GHz frequencies by ultrafast optical probing [5] yielding in conjunction with depth resolved spin noise measurements insights into the origin of inhomogeneous spin dephasing effects at high magnetic fields [5]. Additionally I will present how spin noise spectroscopy can be employed to spatially depth resolve doping profiles with optical resolution [6] and give a summary on easy to implement techniques of spin noise spectroscopy at acoustic frequencies in alkali metal vapors. [4pt] [1] E. Aleksandrov and V. Zapassky, Zh. Eksp. Teor. Fiz. 81, 132 (1981); S. A. Crooker, D. G. Rickel, A. V. Balatsky, and D. L. Smith

  14. Spin dipole and quadrupole resonances in 40Ca

    International Nuclear Information System (INIS)

    Baker, F.T.; Love, W.G.; Bimbot, L.; Fergerson, R.W.; Glashausser, C.; Green, A.; Jones, K.; Nanda, S.

    1989-01-01

    Angular distributions of the double differential cross section d 2 σ/dΩ dE(σ) and the spin-flip probability S nn have been measured for inclusive proton inelastic scattering from 40 Ca at 319 MeV. Excitation energies (ω) up to about 40 MeV have been investigated over the angular range from 3.5 degree to 12 degree in the laboratory (0.3 to 0.9 fm -1 ). Here, multipole decompositions of angular distributions of σS nn for the 40 Ca(rvec p,rvec p ') reaction at 319 MeV have been performed in order to compare ΔS=1 strength observed with sum rules. In contrast to the well-known quenching of Gamow-Teller and M1 resonances, the spin-dipole resonance has a total measured strength which is larger than that predicted by the energy-weighted sum rule. The spin-dipole strength distribution supports asymmetric widths predicted by calculations including 2p-2h mixing. The spin-quadrupole resonance is observed near ω=35 MeV and its total strength for ω<40 MeV estimated

  15. Correlation distance dependence of the resonance frequency of intermolecular zero quantum coherences and its implication for MR thermometry.

    Science.gov (United States)

    Zhang, Le; McCallister, Andrew; Koshlap, Karl M; Branca, Rosa Tamara

    2018-03-01

    Because the resonance frequency of water-fat intermolecular zero-quantum coherences (iZQCs) reflects the water-fat frequency separation at the microscopic scale, these frequencies have been proposed and used as a mean to obtain more accurate temperature information. The purpose of this work was to investigate the dependence of the water-fat iZQC resonance frequency on sample microstructure and on the specific choice of the correlation distance. The effect of water-fat susceptibility gradients on the water-methylene iZQC resonance frequency was first computed and then measured for different water-fat emulsions and for a mixture of porcine muscle and fat. Similar measurements were also performed for mixed heteronuclear spin systems. A strong dependence of the iZQC resonance frequency on the sample microstructure and on the specific choice of the correlation distance was found for spin systems like water and fat that do not mix, but not for spin systems that mix at the molecular level. Because water and fat spins do not mix at the molecular level, the water-fat iZQC resonance frequency and its temperature coefficient are not only affected by sample microstructure but also by the specific choice of the correlation distance. Magn Reson Med 79:1429-1438, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  16. Bodily Tides Near Spin-Orbit Resonances

    Science.gov (United States)

    2012-01-01

    the situation resembles a circuit with a capacitor , where the current leads the voltage.) For a steady deformation, the lag should vanish, and so should...the directional difference between the planetocentric positions of the tide-raising body and the resulting bulge . For example, the principal tide...frequencies χlmpq = |ωlmpq |, the sign of ωlmpq points whether the lagging of the lmpq component of the bulge is positive or negative (falling behind or

  17. Analysis and approximations for crossing two nearby spin resonances

    Energy Technology Data Exchange (ETDEWEB)

    Ranjbar, V. H. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-01-07

    Solutions to the T-BMT spin equation have to date been confined to the single resonance crossing. However, in reality most cases of interest concern the overlapping of several resonances. To date there has been several serious studies of this problem; however, a good analytical solution or even approximation has eluded the community. We show that the T-BMT equation can be transformed into a Hill’s like equation. In this representation it can be shown that, while the single resonance crossing represents the solution to the Parabolic Cylinder equation, the overlapping case becomes a parametric type of resonance. We present possible approximations for both the non-accelerating case and accelerating case.

  18. Spin injection in n-type resonant tunneling diodes.

    Science.gov (United States)

    Orsi Gordo, Vanessa; Herval, Leonilson Ks; Galeti, Helder Va; Gobato, Yara Galvão; Brasil, Maria Jsp; Marques, Gilmar E; Henini, Mohamed; Airey, Robert J

    2012-10-25

    We have studied the polarized resolved photoluminescence of n-type GaAs/AlAs/GaAlAs resonant tunneling diodes under magnetic field parallel to the tunnel current. Under resonant tunneling conditions, we have observed two emission lines attributed to neutral (X) and negatively charged excitons (X-). We have observed a voltage-controlled circular polarization degree from the quantum well emission for both lines, with values up to -88% at 15 T at low voltages which are ascribed to an efficient spin injection from the 2D gases formed at the accumulation layers.

  19. Silicon meets cyclotron: muon spin resonance of organosilicon radicals.

    Science.gov (United States)

    West, Robert; Samedov, Kerim; Percival, Paul W

    2014-07-21

    Muons, generated at a high-powered cyclotron, can capture electrons to form muonium atoms. Muon spin resonance spectra can be recorded for organosilyl radicals obtained by addition of muonium atoms to silylenes and silenes. We present a brief summary of progress in this new area since the first such experiments were reported in 2008. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Optical pump - nuclear resonance probe experiments on spin crossover complexes

    Science.gov (United States)

    Sakshath, S.; Jenni, K.; Scherthan, L.; Würtz, P.; Herlitschke, M.; Sergeev, I.; Strohm, C.; Wille, H.-C.; Röhlsberger, R.; Wolny, J. A.; Schünemann, V.

    2017-11-01

    A novel sample environment enabling optical pump - nuclear resonance probe experiments has been installed at the beamline P01, Petra III, DESY Hamburg. This set-up has been used to investigate optically induced spin state changes of spin crossover (SCO) complexes by nuclear resonant scattering immediately after excitation by an optical laser pulse. Here, we report the technical details as well as first results of the experiments performed at 290 K and 80 K on the SCO complexes [Fe (NH2trz)3]Cl2 and [Fe(PM-BiA)2(NCS)2], respectively. The 57Fe-enriched SCO complexes were excited by a 531 nm laser with a pulse length indicate the presence of high spin (HS) states when the complexes are excited by laser pulses and a pure low spin (LS) state in the absence of any laser pulse. Furthermore, the dependence of the optically excited HS-fraction has been determined as a function of the average optical power.

  1. Electrothermal Frequency Modulated Resonator for Mechanical Memory

    KAUST Repository

    Hafiz, Md Abdullah Al

    2016-08-18

    In this paper, we experimentally demonstrate a mechanical memory device based on the nonlinear dynamics of an electrostatically actuated microelectromechanical resonator utilizing an electrothermal frequency modulation scheme. The microstructure is deliberately fabricated as an in-plane shallow arch to achieve geometric quadratic nonlinearity. We exploit this inherent nonlinearity of the arch and drive it at resonance with minimal actuation voltage into the nonlinear regime, thereby creating softening behavior, hysteresis, and coexistence of states. The hysteretic frequency band is controlled by the electrothermal actuation voltage. Binary values are assigned to the two allowed dynamical states on the hysteretic response curve of the arch resonator with respect to the electrothermal actuation voltage. Set-and-reset operations of the memory states are performed by applying controlled dc pulses provided through the electrothermal actuation scheme, while the read-out operation is performed simultaneously by measuring the motional current through a capacitive detection technique. This novel memory device has the advantages of operating at low voltages and under room temperature. [2016-0043

  2. Spin transfer matrix formulation and snake resonances for polarized proton beams

    International Nuclear Information System (INIS)

    Tepikian, S.

    1986-01-01

    The polarization of a spin polarized proton beam in a circular accelerator is described by a spin transfer matrix. Using this method, they investigate three problems: (1) the crossing of multiple spin resonances, (2) resonance jumping and (3) an accelerator with Siberian snakes. When crossing two (or more) spin resonances, there are no analytic solutions available. However, they can obtain analytic expressions if the two spin resonances are well separated (nonoverlapping) or very close together (overlapping). Between these two extremes they resort to numerical solution of the spin equations. Resonance jumping can be studied using the tools developed for analyzing the cross of multiple spin resonances. These theoretical results compare favorably with experimental results obtained from the AGS at Brookhaven. For large accelerators, resonance jumping becomes impractical and other methods such as Siberian snakes must be used to keep the beam spin polarized. An accelerator with Siberian snakes and isolated spin resonances can be described with a spin transfer matrix. From this, they find a new type of spin depolarizing resonance, called snake resonances

  3. High-frequency dynamics of spin-polarized carriers and photons in a laser

    Science.gov (United States)

    Saha, D.; Basu, D.; Bhattacharya, P.

    2010-11-01

    The high-frequency dynamics of spin-polarized carriers and photons in a spin laser have been studied. The transient response of the device obtained from the rate equations is characterized by two sets of relaxation oscillations in the carrier and photon distributions corresponding to the two polarization modes. Consequently two distinct resonant peaks are observed in the small-signal modulation response. The calculated transient characteristics indicate that the best results are obtained from a spin laser when only the favored polarization mode, with lower threshold, is operational. Under this condition the small-signal modulation bandwidth is higher than that in a conventional laser, the threshold current is lower and the output polarization can be 100% with appropriate bias conditions, independent of the spin polarization of carriers in the active region. Measurements were made at 230 K on a InAs/GaAs quantum dot spin vertical cavity surface emitting laser. A time-averaged output polarization of 55% is measured with an active region spin polarization of 5-6% . The experimental results are in good agreement with calculated data.

  4. 'Al' concentration on spin-dependent resonant tunnelling in InAs/Ga

    Indian Academy of Sciences (India)

    The separation between spin-up and spin-down components, barrier transparency, polarization efficiency and tunnelling lifetime were calculated using the transfer matrix approach. The separation between spin-up and spin-down resonances and tunnelling lifetime were reportedfor the first time in the case of InAs/Ga 1 − y ...

  5. RESPECT: Neutron resonance spin-echo spectrometer for extreme studies

    Energy Technology Data Exchange (ETDEWEB)

    Georgii, R., E-mail: Robert.Georgii@frm2.tum.de [Physik-Department, Technische Universität München, James-Franck-Str. 1, D-85748 Garching (Germany); Heinz Maier-Leibnitz Zentrum, Technische Universität München, Lichtenbergstr. 1, D-85748 Garching (Germany); Kindervater, J. [Physik-Department, Technische Universität München, James-Franck-Str. 1, D-85748 Garching (Germany); Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street Baltimore, MD 21218 (United States); Pfleiderer, C.; Böni, P. [Physik-Department, Technische Universität München, James-Franck-Str. 1, D-85748 Garching (Germany)

    2016-11-21

    We propose the design of a REsonance SPin-echo spECtrometer for exTreme studies, RESPECT, that is ideally suited for the exploration of non-dispersive processes such as diffusion, crystallization, slow dynamics, tunneling processes, crystal electric field excitations, and spin fluctuations. It is a variant of the conventional neutron spin-echo technique (NSE) by (i) replacing the long precession coils by pairs of longitudinal neutron spin-echo coils combined with RF-spin flippers and (ii) by stabilizing the neutron polarization with small longitudinal guide fields that can in addition be used as field subtraction coils thus allowing to adjust the field integrals over a range of 8 orders of magnitude. Therefore, the dynamic range of RESPECT can in principle be varied over 8 orders of magnitude in time, if neutrons with the required energy are made available. Similarly as for existing NSE-spectrometers, spin echo times of up to approximately 1 μs can be reached if the divergence and the correction elements are properly adjusted. Thanks to the optional use of neutron guides and the fact that the currents for the correction coils are much smaller than in standard NSE, intensity gains of at least one order of magnitude are expected, making the concept of RESPECT also competitive for operation at medium flux neutron sources. RESPECT can also be operated in a MIEZE configuration allowing the investigation of relaxation processes in depolarizing environments as they occur when magnetic fields are applied at the sample position, i.e. for the investigation of the dynamics of flux lines in superconductors, magnetic fluctuations in ferromagnetic materials, and samples containing hydrogen.

  6. Terahertz-Frequency Spin Hall Auto-oscillator Based on a Canted Antiferromagnet

    Science.gov (United States)

    Sulymenko, O. R.; Prokopenko, O. V.; Tiberkevich, V. S.; Slavin, A. N.; Ivanov, B. A.; Khymyn, R. S.

    2017-12-01

    We propose a design of a terahertz-frequency signal generator based on a layered structure consisting of a current-driven platinum (Pt) layer and a layer of an antiferromagnet (AFM) with easy-plane anisotropy, where the magnetization vectors of the AFM sublattices are canted inside the easy plane by the Dzyaloshinskii-Moriya interaction (DMI). The dc electric current flowing in the Pt layer creates due to the spin Hall effect, a perpendicular spin current that, being injected in the AFM layer, tilts the DMI-canted AFM sublattices out of the easy plane, thus exposing them to the action of a strong internal exchange magnetic field of the AFM. The sublattice magnetizations, along with the small net magnetization vector mDMI of the canted AFM, start to rotate about the hard anisotropy axis of the AFM with the terahertz frequency proportional to the injected spin current and the AFM exchange field. The rotation of the small net magnetization mDMI results in the terahertz-frequency dipolar radiation that can be directly received by an adjacent (e.g., dielectric) resonator. We demonstrate theoretically that the radiation frequencies in the range f =0.05 - 2 THz are possible at the experimentally reachable magnitudes of the driving current density, and we evaluate the power of the signal radiated into different types of resonators. This power increases with the increase of frequency f , and it can exceed 1 μ W at f ˜0.5 THz for a typical dielectric resonator of the electric permittivity ɛ ˜10 and a quality factor Q ˜750 .

  7. Resonant Frequency Characteristics of a SAW Device Attached to Resonating Micropillars

    Directory of Open Access Journals (Sweden)

    Roy Paily Palathinkal

    2012-03-01

    Full Text Available Recently we reported experimental and simulation results on an increase in resonance frequency of a SAW resonator caused by mass loading of micropillars made of SU-8, attached normal to the surface of the resonator. We concluded that SAW resonator and the SU-8 micropillars in unison form a system of coupled resonators. We have now extended this work and performed a finite element method simulation to study the resonance frequency characteristics of the SAW-based coupled resonator. In this paper we report the effect of the resonance frequency of the micropillars on the resonance frequency of the system of coupled resonators, and observe the coupling of micropillar resonance and the propagating SAW as described in the well known Dybwad system of coupled resonators.

  8. Nuclear spin relaxation/resonance of 8Li in Al

    Science.gov (United States)

    Wang, D.; Salman, Z.; Chow, K. H.; Fan, I.; Hossain, M. D.; Keeler, T. A.; Kiefl, R. F.; Levy, C. D. P.; Mansour, A. I.; Morris, G. D.; Pearson, M. R.; Parolin, T. J.; Saadaoui, H.; Smadella, M.; Song, Q.; MacFarlane, W. A.

    2009-04-01

    A low energy beam of spin polarized 8Li has been used to study the behaviour of isolated 8Li implanted into a 150 nm thick film of Al on an MgO substrate. The spin relaxation rate 1/T1 and β-NMR lineshape were measured as a function of temperature in a large magnetic field of 4.1 T. The resonances from different sites are unresolved due to the large nuclear dipolar interaction with the host 27Al magnetic dipole moments. Nevertheless the temperature variation of the site averaged 1/T1 and Knight shift show evidence for a transition between the octahedral O and substitutional S sites at about 150 K, as observed in other fcc metals.

  9. Characterization of functional LB films using electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Kuroda, Shin-ichi

    1995-01-01

    The role of ESR spectroscopy in the characterization of functional LB films is discussed. Unpaired electrons in LB films are associated with isolated radical molecules produced by charge transfer, paramagnetic metallic ions such as Cu 2+ , strongly interacting spins in the mixed valence states in charge-transfer salts, and so on. These spins often manifest the functions of materials. They can also act as microscopic probes in the ESR analysis devoted for the elucidation of characteristic properties of LB films. In structural studies, ESR is of particular importance in the analysis of molecular orientation of LB films. ESR can unambiguously determine the orientation of molecules through g-value anisotropy: different g value, different resonance field. Two types of new control methods of molecular orientation in LB films originated from the ESR analysis: study of in-plane orientation in dye LB films which led to the discovery of flow-orientation effect, and observation of drastic change of orientation of Cu-porphyrin in LB films using the trigger molecule, n-hexatriacontane. In the studies of electronic properties, hyperfine interactions between electron and nuclear spins provide information about molecular orbitals and local structures. Stable isotopes have been successfully applied to the stable radicals in merocyanine LB films to identify hyperfine couplings. In conducting LB films composed of charge-transfer salts, quasi-one-dimensional antiferromagnetism in semiconducting films and spin resonance of conduction electrons in metallic films are observed. Results provide microscopic evidence for the development of columnar structures of constituent molecules. Development of new functional LB films may provide more cases where ESR spectroscopy will clarify the nature of such films. (author)

  10. Strong excitation of surface and bulk spin waves in yttrium iron garnet placed in a split ring resonator

    Science.gov (United States)

    Tay, Z. J.; Soh, W. T.; Ong, C. K.

    2018-02-01

    This paper presents an experimental study of the inverse spin Hall effect (ISHE) in a bilayer consisting of a yttrium iron garnet (YIG) and platinum (Pt) loaded on a metamaterial split ring resonator (SRR). The system is excited by a microstrip feed line which generates both surface and bulk spin waves in the YIG. The spin waves subsequently undergo spin pumping from the YIG film to an adjacent Pt layer, and is converted into a charge current via the ISHE. It is found that the presence of the SRR causes a significant enhancement of the mangetic field near the resonance frequency of the SRR, resulting in a significant increase in the ISHE signal. Furthermore, the type of spin wave generated in the system can be controlled by changing the external applied magnetic field angle (θH ). When the external applied magnetic field is near parallel to the microstrip line (θH = 0 ), magnetostatic surface spin waves are predominantly excited. On the other hand, when the external applied magnetic field is perpendicular to the microstrip line (θH = π/2 ), backward volume magnetostatic spin waves are predominantly excited. Hence, it can be seen that the SRR structure is a promising method of achieving spin-charge conversion, which has many advantages over a coaxial probe.

  11. Constraining new resonant physics with top spin polarisation information

    Energy Technology Data Exchange (ETDEWEB)

    Englert, Christoph; Nordstroem, Karl [University of Glasgow, SUPA, School of Physics and Astronomy, Glasgow (United Kingdom); Ferrando, James [DESY Hamburg, Hamburg (Germany)

    2017-06-15

    We provide a comprehensive analysis of the power of including top quark-polarisation information to kinematically challenging top pair resonance searches, for which ATLAS and CMS start losing sensitivity. Following the general modelling and analysis strategies pursued by the experiments, we analyse the semi-leptonic and the di-lepton channels and show that including polarisation information can lead to large improvements in the limit setting procedures with large data sets. This will allow us to set stronger limits for parameter choices where sensitivity from the invariant mass of the top pair is not sufficient. This highlights the importance of spin observables as part of a more comprehensive set of observables to gain sensitivity to BSM resonance searches. (orig.)

  12. Measurement of the 14N nuclear quadrupole resonance frequencies by the solid effect

    Science.gov (United States)

    Seliger, J.; Žagar, V.

    2008-07-01

    1H- 14N nuclear quadrupole double resonance using magnetic field cycling between high and low magnetic field and solid effect in the low magnetic field is analyzed in details. The transition probabilities per unit time for the solid-effect transitions are calculated. The double resonance spectra are calculated in the limiting cases of fast and slow nitrogen spin-lattice relaxation. The double resonance spectra are measured in histamine and quinolinic acid. The experimental spectra are analyzed and the 14N NQR frequencies are determined.

  13. Observation of resistively detected hole spin resonance and zero-field pseudo-spin splitting in epitaxial graphene

    Science.gov (United States)

    Mani, Ramesh G.; Hankinson, John; Berger, Claire; de Heer, Walter A.

    2012-01-01

    Electronic carriers in graphene show a high carrier mobility at room temperature. Thus, this system is widely viewed as a potential future charge-based high-speed electronic material to complement–or replace–silicon. At the same time, the spin properties of graphene have suggested improved capability for spin-based electronics or spintronics and spin-based quantum computing. As a result, the detection, characterization and transport of spin have become topics of interest in graphene. Here we report a microwave photo-excited transport study of monolayer and trilayer graphene that reveals an unexpectedly strong microwave-induced electrical response and dual microwave-induced resonances in the dc resistance. The results suggest the resistive detection of spin resonance, and provide a measurement of the g-factor, the spin relaxation time and the sub-lattice degeneracy splitting at zero magnetic field. PMID:22871815

  14. Tilting Styx and Nix but not Uranus with a Spin-Precession-Mean-motion resonance

    Science.gov (United States)

    Quillen, Alice C.; Chen, Yuan-Yuan; Noyelles, Benoît; Loane, Santiago

    2018-02-01

    A Hamiltonian model is constructed for the spin axis of a planet perturbed by a nearby planet with both planets in orbit about a star. We expand the planet-planet gravitational potential perturbation to first order in orbital inclinations and eccentricities, finding terms describing spin resonances involving the spin precession rate and the two planetary mean motions. Convergent planetary migration allows the spinning planet to be captured into spin resonance. With initial obliquity near zero, the spin resonance can lift the planet's obliquity to near 90° or 180° depending upon whether the spin resonance is first or zeroth order in inclination. Past capture of Uranus into such a spin resonance could give an alternative non-collisional scenario accounting for Uranus's high obliquity. However, we find that the time spent in spin resonance must be so long that this scenario cannot be responsible for Uranus's high obliquity. Our model can be used to study spin resonance in satellite systems. Our Hamiltonian model explains how Styx and Nix can be tilted to high obliquity via outward migration of Charon, a phenomenon previously seen in numerical simulations.

  15. High Frequency QPOs due to Black Hole Spin

    Science.gov (United States)

    Kazanas, Demos; Fukumura, K.

    2009-01-01

    We present detailed computations of photon orbits emitted by flares at the innermost stable circular orbit (ISCO) of accretion disks around rotating black holes. We show that for sufficiently large spin parameter, i.e. a > 0.94 M, flare a sufficient number of photons arrive at an observer after multiple orbits around the black hole, to produce an "photon echo" of constant lag, i.e. independent of the relative phase between the black hole and the observer, of T approximates 14 M. This constant time delay, then, leads to a power spectrum with a QPO at a frequency nu approximates 1/14M, even for a totally random ensemble of such flares. Observation of such a QPO will provide incontrovertible evidence for the high spin of the black hole and a very accurate, independent, measurement of its mass.

  16. Collective strong coupling with homogeneous Rabi frequencies using a 3D lumped element microwave resonator

    Energy Technology Data Exchange (ETDEWEB)

    Angerer, Andreas, E-mail: andreas.angerer@tuwien.ac.at; Astner, Thomas; Wirtitsch, Daniel; Majer, Johannes, E-mail: johannes.majer@tuwien.ac.at [Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, 1020 Vienna (Austria); Sumiya, Hitoshi [Sumitomo Electric Industries Ltd., Itami 664-001 (Japan); Onoda, Shinobu [Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Isoya, Junichi [Research Centre for Knowledge Communities, University of Tsukuba, 1-2 Kasuga, Tsukuba, Ibaraki 305-8550 (Japan); Putz, Stefan [Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, 1020 Vienna (Austria); Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States)

    2016-07-18

    We design and implement 3D-lumped element microwave cavities that spatially focus magnetic fields to a small mode volume. They allow coherent and uniform coupling to electron spins hosted by nitrogen vacancy centers in diamond. We achieve large homogeneous single spin coupling rates, with an enhancement of more than one order of magnitude compared to standard 3D cavities with a fundamental resonance at 3 GHz. Finite element simulations confirm that the magnetic field distribution is homogeneous throughout the entire sample volume, with a root mean square deviation of 1.54%. With a sample containing 10{sup 17} nitrogen vacancy electron spins, we achieve a collective coupling strength of Ω = 12 MHz, a cooperativity factor C = 27, and clearly enter the strong coupling regime. This allows to interface a macroscopic spin ensemble with microwave circuits, and the homogeneous Rabi frequency paves the way to manipulate the full ensemble population in a coherent way.

  17. The cosmic axion spin precession experiment (CASPEr): a dark-matter search with nuclear magnetic resonance

    Science.gov (United States)

    Garcon, Antoine; Aybas, Deniz; Blanchard, John W.; Centers, Gary; Figueroa, Nataniel L.; Graham, Peter W.; Kimball, Derek F. Jackson; Rajendran, Surjeet; Gil Sendra, Marina; Sushkov, Alexander O.; Trahms, Lutz; Wang, Tao; Wickenbrock, Arne; Wu, Teng; Budker, Dmitry

    2018-01-01

    The cosmic axion spin precession experiment (CASPEr) is a nuclear magnetic resonance experiment (NMR) seeking to detect axion and axion-like particles which could make up the dark matter present in the Universe. We review the predicted couplings of axions and axion-like particles with baryonic matter that enable their detection via NMR. We then describe two measurement schemes being implemented in CASPEr. The first method, presented in the original CASPEr proposal, consists of a resonant search via continuous-wave NMR spectroscopy. This method offers the highest sensitivity for frequencies ranging from a few Hz to hundreds of MHz, corresponding to masses {m}{{a}}∼ {10}-14–{10}-6 eV. Sub-Hz frequencies are typically difficult to probe with NMR due to the diminishing sensitivity of magnetometers in this region. To circumvent this limitation, we suggest new detection and data processing modalities. We describe a non-resonant frequency-modulation detection scheme, enabling searches from mHz to Hz frequencies ({m}{{a}}∼ {10}-17–{10}-14 eV), extending the detection bandwidth by three decades.

  18. Resonant tunneling via spin-polarized barrier states in a magnetic tunnel junction

    NARCIS (Netherlands)

    Jansen, R.; Lodder, J.C.

    2000-01-01

    Resonant tunneling through states in the barrier of a magnetic tunnel junction has been analyzed theoretically for the case of a spin-polarized density of barrier states. It is shown that for highly spin-polarized barrier states, the magnetoresistance due to resonant tunneling is enhanced compared

  19. Measuring exchange interactions between atomic spins using electron spin resonance STM

    Science.gov (United States)

    Yang, Kai; Paul, William; Natterer, Fabian; Choi, Taeyoung; Heinrich, Andreas; Lutz, Christopher

    Exchange interactions between neighboring atoms give rise to magnetic order in magnetic materials. As the size of the electronic device is miniaturized toward the limit of single atoms, magnetic nanostructures such as coupled atomic dimers and clusters are explored more as prototypes for possible data storage, spintronics as well as quantum computing applications. Characterizing inter-atom exchange interactions calls for increasing spatial resolution and higher energy sensitivity to better understand this fundamental interaction. Here, using spin-polarized scanning tunneling microscopy (STM), we studied a magnetically coupled atomic dimer consisting of two 3d transition metal atoms, with one adsorbed on an insulating layer (MgO) and the other attached to the STM tip. We demonstrate the ability to measure the short-range exchange interaction between the two atomic spins with orders-of-magnitude variation ranging from milli-eV all the way to micro-eV. This is realized by the successful combination of inelastic electron tunneling spectroscopy (IETS) and electron spin resonance (ESR) techniques in STM implemented at different energy scales. We unambiguously confirm the exponential decay behavior of the direct exchange interaction.

  20. Mixed frequency excitation of an electrostatically actuated resonator

    KAUST Repository

    Ramini, Abdallah

    2015-04-24

    We investigate experimentally and theoretically the dynamics of a capacitive resonator under mixed frequency excitation of two AC harmonic signals. The resonator is composed of a proof mass suspended by two cantilever beams. Experimental measurements are conducted using a laser Doppler vibrometer to reveal the interesting dynamics of the system when subjected to two-source excitation. A nonlinear single-degree-of-freedom model is used for the theoretical investigation. The results reveal combination resonances of additive and subtractive type, which are shown to be promising to increase the bandwidth of the resonator near primary resonance frequency. Our results also demonstrate the ability to shift the combination resonances to much lower or much higher frequency ranges. We also demonstrate the dynamic pull-in instability under mixed frequency excitation. © 2015 Springer-Verlag Berlin Heidelberg

  1. Electron spin resonance intercomparison studies on irradiated foodstuffs

    International Nuclear Information System (INIS)

    Raffi, J.

    1992-01-01

    The results of intercomparison studies organized by the Community Bureau of Reference on the use of electron spin resonance spectroscopy for the identification of irradiated food are presented. A qualitative intercomparison was carried out using beef and trout bones, sardine scales, pistachio nut shells, dried grapes and papaya. A quantitative intercomparison involving the use of poultry bones was also organized. There was no difficulty in identifying meat bones, dried grapes and papaya. In the case of fish bones there is a need for further kinetic studies using different fish species. The identification of pistachio nut shells is more complicated and further research is needed prior to the organization of a further intercomparison. Laboratories were able to distinguish between chicken bones irradiated in the range 1 to 3 KGy or 7 to 10 KGy although there was a partial overlap between the results from different laboratories

  2. High-dose dosimetry using electron spin resonance (ESR) spectroscopy

    International Nuclear Information System (INIS)

    Kojima, Takuji; Tanaka, Ryuichi

    1992-01-01

    An electron spin resonance (ESR) dosimeter capable of measuring large doses of radiation in radiotherapy and radiation processing is outlined. In particular, an alanine/ESR dosimeter is discussed, focusing on the development of elements, the development of the ESR dosimetric system, the application of alanine/ESR dosimeter, and basic researches. Rod elements for gamma radiation and x radiation and film elements for electron beams are described in detail. The following recent applications of the alanine/ESR dosimeter are introduced: using as a transfer dosimeter, applying to various types of radiation, diagnosing the deterioration of radiological materials and equipments, and applying to ESR imaging. The future subjects to be solved in the alanine/ESR dosimetric system are referred to as follows: (1) improvement of highly accurate elements suitable for the measurement of various types of radiation, (2) establishment of sensitive calibration method of the ESR equipment itself, and (3) calibration and standardization of radiation doses. (K.N.) 65 refs

  3. AGS Fast spin resonance jump, magnets and power supplies

    International Nuclear Information System (INIS)

    Glenn, J.W.; Huang, H.; Liaw, C. J.; Marneris, I.; Meng, W.; Mi, J. L.; Rosas, P.; Sandberg, J.; Tuozzolo, J.; Zhang, A.

    2009-01-01

    In order to cross more rapidly the 82 weak spin resonances caused by the horizontal tune and the partial snakes, we plan to jump the horizontal tune 82 times during the acceleration of polarized protons. The current in the magnets creating this tune jump will rise in 100 (micro)s, hold flat for about 4 ms and fan to zero in 100 (micro)s. Laminated beam transport quadrupole magnets have been recycled by installing new two turn coils and longitudinal laminated pole tip shims that reduce inductance and power supply current. The power supply uses a high voltage capacitor discharge to raise the magnet current, which is then switched to a low voltage supply, and then the current is switched back to the high voltage capacitor to zero the current. The current in each of the magnet pulses must match the order of magnitude change in proton momentum during the acceleration cycle. The magnet, power supply and operational experience are described

  4. On the Resonant Frequencies of the Oja | Nwachukwu | Nigerian ...

    African Journals Online (AJOL)

    A method for calculating the unblown resonant frequencies of an 'Oja' (a traditional Nigerian musical instrument) is developed. Support for the theory is provided by data derived from experimentally measured spectra of typical oja tones. It is also shown that for resonant frequencies below about 2000Hz, the differences ...

  5. Performance evaluation of beam emanation correction coil for neutron resonance spin echo spectrometer by simulation

    International Nuclear Information System (INIS)

    Maruyama, R.; Tasaki, S.; Hino, M.; Kawabata, Y.

    2004-01-01

    Neutron resonance spin echo (NRSE) method is a spectrometer which uses two RSF (resonance spin flipper) instead of the quietness magnetic field of Mezei type NSE spectrometer, and to measure the change in the speed of the neutron by using the phase difference accumulated in the section between a coupled of RSF in proportion to the resonance frequency of RSF. Having the feature that the magnetic field integration does not depend on the energy resolution by this substitution, and limiting the energy resolution of the NRSE spectrometer become only the beam emanations. The difference of the phase difference by the beam emanation can be corrected by introducing the magnetic field guide with the best magnetic field distribution for the emanation beam. In this research, the beam emanation correction coil for the high-resolution NRSE spectrometer is proposed, and the performance is evaluated by the simulation. As a result, the effectiveness of the correction method proposed by this research was shown. (T.Tanaka)

  6. Light-free magnetic resonance force microscopy for studies of electron spin polarized systems

    International Nuclear Information System (INIS)

    Pelekhov, Denis V.; Selcu, Camelia; Banerjee, Palash; Chung Fong, Kin; Chris Hammel, P.; Bhaskaran, Harish; Schwab, Keith

    2005-01-01

    Magnetic resonance force microscopy is a scanned probe technique capable of three-dimensional magnetic resonance imaging. Its excellent sensitivity opens the possibility for magnetic resonance studies of spin accumulation resulting from the injection of spin polarized currents into a para-magnetic collector. The method is based on mechanical detection of magnetic resonance which requires low noise detection of cantilever displacement; so far, this has been accomplished using optical interferometry. This is undesirable for experiments on doped silicon, where the presence of light is known to enhance spin relaxation rates. We report a non-optical displacement detection scheme based on sensitive microwave capacitive readout

  7. Exploration of horizontal intrinsic spin resonances with two partial Siberian snakes

    Directory of Open Access Journals (Sweden)

    F. Lin

    2007-04-01

    Full Text Available Two partial Siberian snakes were used to avoid all the spin imperfection and vertical intrinsic resonances in the alternating gradient synchrotron (AGS at Brookhaven National Laboratory. However, the horizontal betatron motion can cause polarization loss resulting from the nonvertical stable spin direction in the presence of two partial snakes. This type of resonance, called a horizontal intrinsic spin resonance, was observed and systematically studied in the AGS. A simplified analytic model and numerical simulation have been developed to compare with experimental data. Properties of the horizontal intrinsic resonance are discussed.

  8. Role of spin-transfer torques on synchronization and resonance phenomena in stochastic magnetic oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Accioly, Artur [Instituto de Física, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre (Brazil); Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay (France); Locatelli, Nicolas; Querlioz, Damien; Kim, Joo-Von [Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay (France); Mizrahi, Alice [Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay (France); Unité Mixte de Physique CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, F91767 Palaiseau (France); Pereira, Luis G. [Instituto de Física, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre (Brazil); Grollier, Julie [Unité Mixte de Physique CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, F91767 Palaiseau (France)

    2016-09-07

    A theoretical study on how synchronization and resonance-like phenomena in superparamagnetic tunnel junctions can be driven by spin-transfer torques is presented. We examine the magnetization of a superparamagnetic free layer that reverses randomly between two well-defined orientations due to thermal fluctuations, acting as a stochastic oscillator. When subject to an external ac forcing, this system can present stochastic resonance and noise-enhanced synchronization. We focus on the roles of the mutually perpendicular damping-like and field-like torques, showing that the response of the system is very different at low and high frequencies. We also demonstrate that the field-like torque can increase the efficiency of the current-driven forcing, especially at sub-threshold electric currents. These results can be useful for possible low-power, more energy efficient applications.

  9. Design of a triple resonance magic angle sample spinning probe for high field solid state nuclear magnetic resonance

    Science.gov (United States)

    Martin, Rachel W.; Paulson, Eric K.; Zilm, Kurt W.

    2003-06-01

    Standard design and construction practices used in building nuclear magnetic resonance (NMR) probes for the study of solid state samples become difficult if not entirely impractical to implement as the 1H resonance frequency approaches the self resonance frequency of commercial capacitors. We describe an approach that utilizes short variable transmission line segments as tunable reactances. Such an approach effectively controls stray reactances and provides a higher Q alternative to ceramic chip capacitors. The particular probe described is built to accommodate a 2.5 mm magic angle spinning rotor system, and is triply tuned to 13C, 15N, and 1H frequencies for use at 18.8 T (200, 80, and 800 MHz, respectively). Isolation of the three radio frequency (rf) channels is achieved using both a rejection trap and a transmission line notch filter. The compact geometry of this design allows three channels with high power handling capability to fit in a medium bore (63 mm) magnet. Extended time variable temperature operation is integral to the mechanical design, enabling the temperature control necessary for investigation of biological macromolecules. Accurate measurement of the air temperature near the sample rotor is achieved using a fiber optic thermometer, which does not interfere with the rf electronics. We also demonstrate that acceptable line shapes are only readily achieved using zero magnetic susceptibility wire in construction of the sample coil. Computer simulation of the circuit aided in the physical design of the probe. Representative data illustrating the efficiency, rf homogeneity, and signal to noise factor of the probe are presented.

  10. Spin-torque ferromagnetic resonance in arbitrarily magnetized thin films

    Science.gov (United States)

    Sklenar, Joseph

    The spin Hall effect (SHE) in non-magnetic metals can be used to generate spin-transfer-torque (STT), subsequently inducing ferromagnetic resonance (FMR) in magnetic thin films; this experimental method is termed spin-torque ferromagnetic resonance (ST-FMR). Most ST-FMR experiments that are reported have an applied magnetic field in the plane of the sample and the research focuses on material combinations that have large and efficient STT. The most common way ST-FMR signals are detected is through an anisotropic magnetoresistance (AMR) rectification process. In this work we will present ST-FMR results in thin films where the magnetization has both an in-plane and out-of-plane component. The arbitrary magnetization direction is achieved by tipping the applied magnetic field out of the sample plane. We find that when the material system is a permalloy/Pt bilayer, ST-FMR signals are not mirror-symmetric upon magnetic field reversal . This is because the combination of both a STT from the bulk SHE and the Oersted field-like torque from the device do not drive the dynamics in the same manner when the field is reversed. We interpret our results in the Py/Pt experiment by extending an already established ST-FMR lineshape model to describe the general case of arbitrarily magnetized films. We compare and contrast our Py/Pt experiment with another system we measured, a Py/MoS2 bilayer. For the Py/MoS2 system, in-plane experiments suggest that a large STT is present and are comparable to what is observed for the more traditional Py/Pt system . On the other hand, the out-of-plane experiment for the Py/MoS2 system is qualitatively very different from Py/Pt. Our results suggest that ST-FMR experiments for arbitrarily magnetized magnetic films are useful in characterizing STT generated from interface rather than bulk effects. Work at Northwestern was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Science and Engineering Division under grant

  11. Resonant difference-frequency atomic force ultrasonic microscope

    Science.gov (United States)

    Cantrell, John H. (Inventor); Cantrell, Sean A. (Inventor)

    2010-01-01

    A scanning probe microscope and methodology called resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM), employs an ultrasonic wave launched from the bottom of a sample while the cantilever of an atomic force microscope, driven at a frequency differing from the ultrasonic frequency by one of the contact resonance frequencies of the cantilever, engages the sample top surface. The nonlinear mixing of the oscillating cantilever and the ultrasonic wave in the region defined by the cantilever tip-sample surface interaction force generates difference-frequency oscillations at the cantilever contact resonance. The resonance-enhanced difference-frequency signals are used to create images of nanoscale near-surface and subsurface features.

  12. Variable frequency iteration MPPT for resonant power converters

    Science.gov (United States)

    Zhang, Qian; Bataresh, Issa; Chen, Lin

    2015-06-30

    A method of maximum power point tracking (MPPT) uses an MPPT algorithm to determine a switching frequency for a resonant power converter, including initializing by setting an initial boundary frequency range that is divided into initial frequency sub-ranges bounded by initial frequencies including an initial center frequency and first and second initial bounding frequencies. A first iteration includes measuring initial powers at the initial frequencies to determine a maximum power initial frequency that is used to set a first reduced frequency search range centered or bounded by the maximum power initial frequency including at least a first additional bounding frequency. A second iteration includes calculating first and second center frequencies by averaging adjacent frequent values in the first reduced frequency search range and measuring second power values at the first and second center frequencies. The switching frequency is determined from measured power values including the second power values.

  13. Spin motion at and near orbital resonance in storage rings with Siberian snakes I. At orbital resonance

    International Nuclear Information System (INIS)

    Barber, D.P.; Vogt, M.

    2006-12-01

    Here, and in a sequel, we invoke the invariant spin field to provide an in-depth study of spin motion at and near low order orbital resonances in a simple model for the effects of vertical betatron motion in a storage ring with Siberian Snakes. This leads to a clear understanding, within the model, of the behaviour of the beam polarization at and near so-called snake resonances in proton storage rings. (orig.)

  14. Spin motion at and near orbital resonance in storage rings with Siberian snakes I. At orbital resonance

    Energy Technology Data Exchange (ETDEWEB)

    Barber, D.P.; Vogt, M.

    2006-12-15

    Here, and in a sequel, we invoke the invariant spin field to provide an in-depth study of spin motion at and near low order orbital resonances in a simple model for the effects of vertical betatron motion in a storage ring with Siberian Snakes. This leads to a clear understanding, within the model, of the behaviour of the beam polarization at and near so-called snake resonances in proton storage rings. (orig.)

  15. Low-frequency spin dynamics and NMR spin-lattice relaxation in antiferromagnetic rings

    Science.gov (United States)

    Itou, T.; Sagane, T.; Oyamada, A.; Maegawa, S.; Igarashi, S.; Yukawa, Y.

    2011-01-01

    We develop a general theory of the spin dynamics of Heisenberg antiferromagnetic rings (HAFRs) that explains the mechanism of NMR spin-lattice relaxation at low temperatures. In HAFRs, the imaginary parts of the q-summed dynamic spin susceptibilities parallel and perpendicular to an applied static field, χsum∥″(ω) and χsum⊥″(ω), are composed of the sum of many slightly broadened δ-functional modes at many frequencies. The NMR relaxation is caused by the quasielastic mode in χsum∥″(ω) at around zero frequency. This quasielastic mode is characterized by two physical quantities, intensity P0∥ and frequency width Γ0∥. Although P0∥ has to date been assumed to be identical to the uniform static susceptibility, we point out that the two quantities are not identical. Without making this unreliable assumption for P0∥, we demonstrate experimentally how P0∥ and Γ0∥ behave, by analyzing the NMR relaxation rates of two different nuclei, H1 and C13, in a real HAFR. This analysis is more rigorous and thus can be used to estimate Γ0∥ and P0∥ more precisely than previously possible. We find that the temperature dependence of P0∥ exhibits activation-type behavior reflecting the first excitation gap. We also find that Γ0∥ decreases monotonically on cooling but saturates to a nonzero value at zero temperature. This strongly suggests that Γ0∥ is dominated not only by the electron-phonon interactions but also by internanomagnet dipole interactions, which have been neglected to date.

  16. Effects of Be acceptors on the spin polarization of carriers in p-i-n resonant tunneling diodes

    Energy Technology Data Exchange (ETDEWEB)

    Awan, I. T.; Galvão Gobato, Y. [Departamento de Física, Universidade Federal de São Carlos (UFSCAR) 13560-905, São Carlos, SP (Brazil); Galeti, H. V. A. [Departamento de Engenharia Elétrica, Universidade Federal de São Carlos 13560-905, São Carlos, SP (Brazil); Brasil, M. J. S. P. [Institute of Physics Gleb Wataghin, UNICAMP, Campinas (Brazil); Taylor, D.; Henini, M. [School of Physics and Astronomy, Nottingham Nanotechnology and Nanoscience Centre, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2014-08-07

    In this paper, we have investigated the effect of Be acceptors on the electroluminescence and the spin polarization in GaAs/AlAs p-i-n resonant tunneling diodes. The quantum well emission comprise two main lines separated by ∼20 meV attributed to excitonic and Be-related transitions, which intensities show remarkably abrupt variations at critical voltages, particularly at the electron resonant peak where it shows a high-frequency bistability. The circular-polarization degree of the quantum-well electroluminescence also shows strong and abrupt variations at the critical bias voltages and it attains relatively large values (of ∼−75% at 15 T). These effects may be explored to design novel devices for spintronic applications such as a high-frequency spin-oscillators.

  17. A Quarter Ellipse Microstrip Resonator for Filters in Microwave Frequencies

    Directory of Open Access Journals (Sweden)

    Samuel Á. Jaramillo-Flórez

    2013-11-01

    Full Text Available This work describes the results of computational simulations and construction of quadrant elliptical resonators excited by coplanar slot line waveguide for designing microwave filters in RF communications systems. By means of the equation of optics, are explained the fundamentals of these geometry of resonators proposed. Are described the construction of quadrant elliptical resonators, one of microstrip and other two of cavity, of size different, and an array of four quadrant elliptical resonators in cascade. The results of the measures and the computational calculus of scattering S11 and S21 of elliptical resonators is made for to identify the resonant frequencies of the resonators studied, proving that these have performance in frequency as complete ellipses by the image effect due to their two mirror in both semiaxis, occupying less area, and the possible applications are discussed.

  18. Spin dynamics of the positive muon radicals in the presence of rapid electron spin exchange: frequency shift and relaxation

    International Nuclear Information System (INIS)

    Senba, Masayoshi; British Columbia Univ., Vancouver, BC

    1991-01-01

    The spin dynamics of the positive muon in a muonium-like radical has been investigated in the case where the unpaired electron of the radical undergoes rapid spin flip collisions. If the spin flip rate λ SF is much faster than the hyperfine frequency of the radical, the behaviour of the muon spin is very similar to that of a positive muon in diamagnetic environments. It has been shown that in a transverse field, the relaxation rate and precession frequency of the apparent diamagnetic muon are related to the time evolution function of the muon spin in muonium. The relaxation rate of such an apparent diamagnetic signal has a characteristic field dependence which is very sensitive to the hyperfine frequency of the radical. The fractional frequency shift with respect to the positive muon precession frequency (ω D -ω μ )/ω μ is shown to be field-dependent, in contrast to the case of Knight shifts in metals. The field dependence of the relaxation and frequency shift will provide a tool to distinguish experimentally the muon in a radical which behaves like a free positive muon from a genuine diamagnetic muon. This work can be applied to a variety of fields involving muonium and hydrogen, such as spin dynamic in the gas phase and the muonium-like (hydrogen-like) states in semiconductors. The case where the muon undergoes both spin flip and charge transfer collisions is also discussed. (author)

  19. Equivalence of two formalisms for calculating higher order synchrotron sideband spin resonances

    International Nuclear Information System (INIS)

    Mane, S.R.

    1988-01-01

    Synchrotron sideband resonances of a first order spin resonance are generally regarded as the most important higher order spin resonances in a high-energy storage ring. Yokoya's formula for these resonances is rederived, including some extra terms, which he neglected, but which turn out to be of comparable magnitude to the terms retained. Including these terms, Yokoya's formalism and the SMILE algorithm are shown to be equivalent to leading order in the resonance strengths. The theoretical calculations are shown to agree with certain measurements from SPEAR

  20. Phononic frequency comb via three-mode parametric resonance

    Science.gov (United States)

    Ganesan, Adarsh; Do, Cuong; Seshia, Ashwin

    2018-01-01

    This paper is motivated by the recent demonstration of a phononic frequency comb. While previous experiments have shown the existence of a three-wave mixing pathway in a system of two-coupled phonon modes, this work demonstrates a similar pathway in a system of three-coupled phonon modes. This paper also presents a number of interesting experimental facts concomitant to the three-mode parametric resonance based frequency comb observed in a specific micromechanical device. The experimental validation of frequency combs via three-mode parametric resonance along with the previous demonstration of two-mode frequency combs points to the ultimate possibility of multimode frequency combs.

  1. Detection and characterisation of radicals using electron paramagnetic resonance (EPR) spin trapping and related methods

    DEFF Research Database (Denmark)

    Davies, Michael Jonathan

    2016-01-01

    Electron paramagnetic resonance (EPR) spectroscopy (also known as electron spin resonance, ESR, or electron magnetic resonance, EMR, spectroscopy) is often described as the “gold standard” for the detection and characterisation of radicals in chemical, biological and medical systems. The article...

  2. Measuring absolute spin polarization in dissolution-DNP by Spin PolarimetrY Magnetic Resonance (SPY-MR).

    Science.gov (United States)

    Vuichoud, Basile; Milani, Jonas; Chappuis, Quentin; Bornet, Aurélien; Bodenhausen, Geoffrey; Jannin, Sami

    2015-11-01

    Dynamic nuclear polarization at 1.2 K and 6.7 T allows one to achieve spin temperatures on the order of a few millikelvin, so that the high-temperature approximation (ΔEPolarimetrY Magnetic Resonance (SPY-MR), is illustrated for various pairs of (13)C spins (I, S) in acetate and pyruvate. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  3. Electron Tunneling in Lithium Ammonia Solutions Probed by Frequency-Dependent Electron-Spin Relaxation Studies

    Science.gov (United States)

    Maeda, Kiminori; Lodge, Matthew T.J.; Harmer, Jeffrey; Freed, Jack H.; Edwards, Peter P.

    2012-01-01

    Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T1) and spin-spin (T2) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multi-exponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1–10)×10−12 s over a temperature range 230–290K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a timescale of ca. 10−13 s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great potential

  4. Dresselhaus spin-orbit coupling induced spin-polarization and resonance-split in n-well semiconductor superlattices

    International Nuclear Information System (INIS)

    Ye Chengzhi; Xue Rui; Nie, Y.-H.; Liang, J.-Q.

    2009-01-01

    Using the transfer matrix method, we investigate the electron transmission over multiple-well semiconductor superlattices with Dresselhaus spin-orbit coupling in the potential-well regions. The superlattice structure enhances the effect of spin polarization in the transmission spectrum. The minibands of multiple-well superlattices for electrons with different spin can be completely separated at the low incident energy, leading to the 100% spin polarization in a broad energy windows, which may be an effective scheme for realizing spin filtering. Moreover, for the transmission over n-quantum-well, it is observed that the resonance peaks in the minibands split into n-folds or (n-1)-folds depending on the well-width and barrier-thickness, which is different from the case of tunneling through n-barrier structure

  5. SETI at the spin-flip line frequency of positronium.

    Science.gov (United States)

    Mauersberger, R.; Wilson, T. L.; Rood, R. T.; Bania, T. M.; Hein, H.; Linhart, A.

    1996-02-01

    A directed search for extraterrestrial intelligence (SETI) has been carried out using the IRAM 30m telescope. Following a suggestion by Kardashev (1979), the search was conducted at the spin-flip line of the lightest atom, namely positronium, at 203GHz. Most of the 17 targets are mature stars with excess infrared radiation, which might be the waste heat of a power-rich technological civilisation. The rest frame of the cosmic background radiation was chosen as the velocity frame. The spectral resolution used was 9.7kHz. From the noise level, which was determined by the limited telescope time and weather conditions, the upper limit for the power of artificial omnidirectional transmitters at the positronium line frequency is of order 10^15^W. The relevance of this non-detection is discussed.

  6. High Energy Single Frequency Resonant Amplifier, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR phase I project proposes a single frequency high energy resonant amplifier for remote sensing. Current state-of-art technologies can not provide all...

  7. Low frequency wave resonance in fringing reef environments

    NARCIS (Netherlands)

    Pomeroy, A.W.M.; van Dongeren, A.; Lowe, R.J.; Van Thiel de Vries, J.S.M.; Roelvink, J.A.

    2012-01-01

    Low frequency wave resonance has been postulated to enhance damage to coral reef protected coastlines during storm events. This paper uses the numerical model XBeach to examine the dynamics that contribute to resonance that have been previously observed on a fringing reef on Guam during tropical

  8. Method and apparatus for resonant frequency waveform modulation

    Science.gov (United States)

    Taubman, Matthew S [Richland, WA

    2011-06-07

    A resonant modulator device and process are described that provide enhanced resonant frequency waveforms to electrical devices including, e.g., laser devices. Faster, larger, and more complex modulation waveforms are obtained than can be obtained by use of conventional current controllers alone.

  9. Electron spin resonance study of radicals in irradiated polyethylene

    International Nuclear Information System (INIS)

    Fujimura, Takashi

    1979-02-01

    In order to elucidate radiation effect in polyethylene, the nature and behavior of radicals produced in polyethylene and the model compound of polyethylene irradiated at 77 0 K were studied by using electron spin resonance. The structure of radical pairs, which are composed of two radicals produced very closely each other, was investigated in drawn polyethylene and the single crystal of n-eicosane. The radical pairs of intrachain type and interchain type were found in polyethylene and n-eicosane respectively. It was suggested that these two types of radical pairs are the precursors of double bonds and crosslinks respectively. The thermal decay reactions of radicals themselves produced in irradiated polyethylene were investigated. It was made clear that the short range distances between two radicals play an important role in the decay reaction of alkyl radicals at low temperatures. The trapping regions of radicals were studied and it was clarified that allyl radicals, which are produced by the reaction of alkyl radicals with double bonds, are trapped both in the crystalline and non-crystalline regions. (author)

  10. Electron spin resonance studies of carbonates and phosphates

    International Nuclear Information System (INIS)

    Seletchi, Emilia Dana

    2005-01-01

    Electron Spin Resonance (ESR) is an absolute dating technique suitable for the Quaternary, which can be applied to a wide range of archaeological and geological materials. This method is mostly used to date such things as calcium carbonate in limestone, stalactites, stalagmites, mollusk shells, and corals. The results show that and are the most commonly present radiation-induced defects in bicarbonates. A new methodology for the provenance of ancient monuments and artifacts was developed by using a large number of marble spectrum parameters. The sextet, dominant in the spectra, other peaks due to lattice defects, and organic radicals have been used in the persistent effort to characterize marble quarries. In ESR dating and dosimetry we can measure the intensity of an ESR signal and its enhancement by artificial irradiation with the absorbed dose. ESR retrospective dosimetry has proven to be a very useful technique for dose assessment in past radiation accidents. Human exposure can be determined directly from the ESR signal of tooth enamel. The majority of radiation-induced radicals in tooth enamel are carbonate derived: CO 2 - ; CO 3 - ; CO - ; CO 3 3- , but radicals derived from phosphate and oxygen were also identified. (author)

  11. Theoretical evaluation of the electron paramagnetic resonance spin ...

    Indian Academy of Sciences (India)

    The impurity displacements for Fe3+ and Ru3+ in corundum (Al2O3) are theoretically studied using the perturbation formulas of the spin Hamiltonian parameters (zero-field splitting and anisotropic factors) for a 3d5 (with high spin = 5/2) and a 4d5 (with low spin = 1/2) ion in trigonal symmetry, respectively. According ...

  12. 3C-SiC microdisk mechanical resonators with multimode resonances at radio frequencies

    Science.gov (United States)

    Lee, Jaesung; Zamani, Hamidrera; Rajgopal, Srihari; Zorman, Christian A.; X-L Feng, Philip

    2017-07-01

    We report on the design, modeling, fabrication and measurement of single-crystal 3C-silicon carbide (SiC) microdisk mechanical resonators with multimode resonances operating at radio frequencies (RF). These microdisk resonators (center-clamped on a vertical stem pedestal) offer multiple flexural-mode resonances with frequencies dependent on both disk and anchor dimensions. The resonators are made using a novel fabrication method comprised of focused ion beam nanomachining and hydroflouic : nitric : acetic (HNA) acid etching. Resonance peaks (in the frequency spectrum) are detected through laser-interferometry measurements. Resonators with different dimensions are tested, and multimode resonances, mode splitting, energy dissipation (in the form of quality factor measurement) are investigated. Further, we demonstrate a feedback oscillator based on a passive 3C-SiC resonator. This investigation provides important guidelines for microdisk resonator development, ranging from an analytical prediction of frequency scaling law to fabrication, suggesting RF microdisk resonators can be good candidates for future sensing applications in harsh environments.

  13. Electron tunneling in lithium-ammonia solutions probed by frequency-dependent electron spin relaxation studies.

    Science.gov (United States)

    Maeda, Kiminori; Lodge, Matthew T J; Harmer, Jeffrey; Freed, Jack H; Edwards, Peter P

    2012-06-06

    Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T(1)) and spin-spin (T(2)) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multiexponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1-10) × 10(-12) s over a temperature range 230-290 K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a time scale of ∼10(-13) s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great

  14. Quantum Entanglement of a Tunneling Spin with Mechanical Modes of a Torsional Resonator

    Directory of Open Access Journals (Sweden)

    D. A. Garanin

    2011-08-01

    Full Text Available We solve the Schrödinger equation for various quantum regimes describing a tunneling macrospin coupled to a torsional oscillator. The energy spectrum and freezing of spin tunneling are studied. Magnetic susceptibility, noise spectrum, and decoherence due to entanglement of spin and mechanical modes are computed. We show that the presence of a tunneling spin can be detected via splitting of the mechanical mode at the resonance. Our results apply to experiments with magnetic molecules coupled to nanoresonators.

  15. ON THE RESONANT FREQUENCIES OF THE OJA

    African Journals Online (AJOL)

    Dr Obe

    1997-09-01

    Sep 1, 1997 ... the lower tone hole. A note is sounded by the flautist blowing a stream of air across the embouchure and fingering the tone holes as desired. The lips, the ... noise. (4). Frequency, FX,. (HZ) (5). Ration to dominant frequency. (6). All tone holes closed. 687 a. 9. 748. 0.64. E5 (660 HZ). -8.2. 1274 b. 30. 1175.

  16. Neutron Resonance Spin Flippers: Static Coils Manufactured by Electrical Discharge Machining

    OpenAIRE

    Martin, N.; Wagner, J. N.; Dogú, M.; Fuchs, C.; Kredler, L.; Böni, P.; Häussler, W.

    2014-01-01

    Radiofrequency spin flippers (RFSF) are key elements of Neutron Resonance Spin Echo (NRSE) spectrometers, which allow performing controlled manipulations of the beam polarization. We report on the design and test of a new type of RFSF which originality lies in the new manufacturing technique for the static coil. The largely automated procedure ensures reproducible construction as well as an excellent homogeneity of the neutron magnetic resonance condition over the coil volume. Two salient fea...

  17. Sealed magic angle spinning nuclear magnetic resonance probe and process for spectroscopy of hazardous samples

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Herman M.; Washton, Nancy M.; Mueller, Karl T.; Sears, Jr., Jesse A.; Townsend, Mark R.; Ewing, James R.

    2016-06-14

    A magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) probe is described that includes double containment enclosures configured to seal and contain hazardous samples for analysis. The probe is of a modular design that ensures containment of hazardous samples during sample analysis while preserving spin speeds for superior NMR performance and convenience of operation.

  18. Magnetic Resonance Imaging of Biological Specimens by Electron Paramagnetic Resonance of Nitroxide Spin Labels

    Science.gov (United States)

    Berliner, Lawrence J.; Fujii, Hirotada

    1985-02-01

    Electron paramagnetic resonance imaging was demonstrated on two plant species, Apium graveolens and Coleus blumei. This was accomplished by soaking stems of these plants in the paramagnetic nitroxide imaging agent 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl. The experiments were accomplished at L-band frequency (1.4 to 1.9 gigahertz) with single-turn, flat-loop surface coils. One-dimensional imaging spectra were diagnostic of capillary structure and long-term stability.

  19. Spin-Mechatronics

    Science.gov (United States)

    Matsuo, Mamoru; Saitoh, Eiji; Maekawa, Sadamichi

    2017-01-01

    We investigate the interconversion phenomena between spin and mechanical angular momentum in moving objects. In particular, the recent results on spin manipulation and spin-current generation by mechanical motion are examined. In accelerating systems, spin-dependent gauge fields emerge, which enable the conversion from mechanical angular momentum into spins. Such a spin-mechanical effect is predicted by quantum theory in a non-inertial frame. Experiments which confirm the effect, i.e., the resonance frequency shift in nuclear magnetic resonance, the stray field measurement of rotating metals, and electric voltage generation in liquid metals, are discussed.

  20. Spin pumping through a topological insulator probed by x-ray detected ferromagnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa, A.I., E-mail: aifigueg@gmail.com [Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom); Baker, A.A. [Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom); Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Collins-McIntyre, L.J.; Hesjedal, T. [Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Laan, G. van der [Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom)

    2016-02-15

    In the field of spintronics, the generation of a pure spin current (without macroscopic charge flow) through spin pumping of a ferromagnetic (FM) layer opens up the perspective of a new generation of dissipation-less devices. Microwave driven ferromagnetic resonance (FMR) can generate a pure spin current that enters adjacent layers, allowing for both magnetization reversal (through spin-transfer torque) and to probe spin coherence in non-magnetic materials. However, standard FMR is unable to probe multilayer dynamics directly, since the measurement averages over the contributions from the whole system. The synchrotron radiation-based technique of x-ray detected FMR (XFMR) offers an elegant solution to this drawback, giving access to element-, site-, and layer-specific dynamical measurements in heterostructures. In this work, we show how XFMR has provided unique information to understand spin pumping and spin transfer torque effects through a topological insulator (TI) layer in a pseudo-spin valve heterostructure. We demonstrate that TIs function as efficient spin sinks, while also allowing a limited dynamic coupling between ferromagnetic layers. These results shed new light on the spin dynamics of this novel class of materials, and suggest future directions for the development of room temperature TI-based spintronics. - Highlights: • X-ray detected ferromagnetic resonance is used to study the spin pumping phenomenon. • We show a powerful way to get information of spin transfer between magnetic layers. • We observe spin pumping through a topological insulators at room temperature. • Topological insulators function as efficient spin sinks.

  1. Spin pumping through a topological insulator probed by x-ray detected ferromagnetic resonance

    International Nuclear Information System (INIS)

    Figueroa, A.I.; Baker, A.A.; Collins-McIntyre, L.J.; Hesjedal, T.; Laan, G. van der

    2016-01-01

    In the field of spintronics, the generation of a pure spin current (without macroscopic charge flow) through spin pumping of a ferromagnetic (FM) layer opens up the perspective of a new generation of dissipation-less devices. Microwave driven ferromagnetic resonance (FMR) can generate a pure spin current that enters adjacent layers, allowing for both magnetization reversal (through spin-transfer torque) and to probe spin coherence in non-magnetic materials. However, standard FMR is unable to probe multilayer dynamics directly, since the measurement averages over the contributions from the whole system. The synchrotron radiation-based technique of x-ray detected FMR (XFMR) offers an elegant solution to this drawback, giving access to element-, site-, and layer-specific dynamical measurements in heterostructures. In this work, we show how XFMR has provided unique information to understand spin pumping and spin transfer torque effects through a topological insulator (TI) layer in a pseudo-spin valve heterostructure. We demonstrate that TIs function as efficient spin sinks, while also allowing a limited dynamic coupling between ferromagnetic layers. These results shed new light on the spin dynamics of this novel class of materials, and suggest future directions for the development of room temperature TI-based spintronics. - Highlights: • X-ray detected ferromagnetic resonance is used to study the spin pumping phenomenon. • We show a powerful way to get information of spin transfer between magnetic layers. • We observe spin pumping through a topological insulators at room temperature. • Topological insulators function as efficient spin sinks.

  2. Spin-orbit-induced strong coupling of a single spin to a nanomechanical resonator

    DEFF Research Database (Denmark)

    Pályi, András; Struck, P R; Rudner, Mark

    2012-01-01

    We theoretically investigate the deflection-induced coupling of an electron spin to vibrational motion due to spin-orbit coupling in suspended carbon nanotube quantum dots. Our estimates indicate that, with current capabilities, a quantum dot with an odd number of electrons can serve....... The strong intrinsic spin-mechanical coupling allows for detection, as well as manipulation of the spin qubit, and may yield enhanced performance of nanotubes in sensing applications....

  3. Voltage-controlled spin selection in a magnetic resonant tunneling diode.

    Science.gov (United States)

    Slobodskyy, A; Gould, C; Slobodskyy, T; Becker, C R; Schmidt, G; Molenkamp, L W

    2003-06-20

    We have fabricated all II-VI semiconductor resonant tunneling diodes based on the (Zn,Mn,Be)Se material system, containing dilute magnetic material in the quantum well, and studied their current-voltage characteristics. When subjected to an external magnetic field the resulting spin splitting of the levels in the quantum well leads to a splitting of the transmission resonance into two separate peaks. This is interpreted as evidence of tunneling transport through spin polarized levels, and could be the first step towards a voltage controlled spin filter.

  4. Effect of electron-beam momentum spread on cyclotron resonance maser operation at two resonant frequencies

    Science.gov (United States)

    Hunter, G. J.; McNeil, B. W. J.; Robb, G. R. M.

    2001-09-01

    We present a theoretical analysis of cyclotron resonance maser (CRM) operation at two resonant frequencies including the effects of momentum spread in the electron beam. A linear analysis of the system equations is presented in the limit of small momentum spreads. Numerical solutions to the system equations are also given and are in agreement with the linear theory. The results predict that for realistic momentum spreads, operation of the CRM at the higher of the two resonant frequencies should be possible, extending its operating frequency range. An experiment currently under development at Strathclyde University is described and modeled numerically.

  5. Geometry dependence of temperature coefficient of resonant frequency in highly sensitive resonant thermal sensors

    Science.gov (United States)

    Inomata, Naoki; Ono, Takahito

    2017-08-01

    In this paper, the geometry dependence of the temperature coefficient of resonant frequency (TCRF) is investigated and compared with a theoretical thermal stress change using Si mechanical microresonators. The used resonators have Y, T, I (conventional double-supported type) and arrow shapes, and in each shape the resonant frequency change of the resonator is measured in relation to changes in the amount of heat input to the resonator. The change trend in the experimental resonant frequency and the theoretical thermal stress in changing the temperature are consist. The TCRF in each resonator is Y: -653, T: -162, I: -417, and the arrow is 174 ppm/K. These absolute values are much higher than those of conventional cantilevered Si resonators (-34.9 ppm/K). In addition, the frequency fluctuations based on Allan deviation are experimentally evaluated considering the theoretical thermal fluctuation noise. It is considered that use of this technique to improve the TCRF of resonators by changing the geometry has the possibility of creating a sensor with highly sensitive thermal detection.

  6. Quantum size effects on spin-tunneling time in a magnetic resonant tunneling diode

    OpenAIRE

    Saffarzadeh, Alireza; Daqiq, Reza

    2009-01-01

    We study theoretically the quantum size effects of a magnetic resonant tunneling diode (RTD) with a (Zn,Mn)Se dilute magnetic semiconductor layer on the spin-tunneling time and the spin polarization of the electrons. The results show that the spin-tunneling times may oscillate and a great difference between the tunneling time of the electrons with opposite spin directions can be obtained depending on the system parameters. We also study the effect of structural asymmetry which is related to t...

  7. Electron spin resonance characterization of a multi-nitrogen complex in diamond

    CERN Document Server

    Iakoubovskii, K

    2002-01-01

    The W27 centre has been characterized by means of electron spin resonance in natural diamond. The centre exhibits spin S=1, a large spin-spin coupling constant D=99 mT, and a complex hyperfine interaction structure interpreted as originating from interaction of an S=1 electronic system with five nitrogen atoms: two of these sites are equivalent and are located near the S = 1 electrons; three others are nearly equivalent and more remote. The centre is suggested to include a divacancy, where one vacancy, bound to two nitrogen atoms and one carbon atom, has trapped an extra electron, while the second vacancy is bound to three substitutional nitrogen atoms.

  8. Mitigating Thermoelastic Dissipation of Flexural Micromechanical Resonators by Decoupling Resonant Frequency from Thermal Relaxation Rate

    Science.gov (United States)

    Zhou, Xin; Xiao, Dingbang; Wu, Xuezhong; Li, Qingsong; Hou, Zhanqiang; He, Kaixuan; Wu, Yulie

    2017-12-01

    This paper reports an alternative design strategy to reduce thermoelastic dissipation (TED) for isothermal-mode micromechanical resonators. This involves hanging lumped masses on a frame structure to decouple the resonant frequency and the effective beamwidth of the resonators, which enables the separation of the thermal relaxation rate and frequency of vibration. This approach is validated using silicon-based micromechanical disklike resonators engineered to isolate TED. A threefold improvement in the quality factor and a tenfold improvement in the decay-time constant is demonstrated. This work proposes a solution for isothermal-mode (flexural) micromechanical resonators to effectively mitigate TED. Specifically, this approach is ideal for designing high-performance gyroscope resonators based on microelectromechanical systems (MEMS) technology. It may pave the way for the next generation inertial-grade MEMS gyroscope, which remains a great challenge and is very appealing.

  9. High-Frequency Dynamics Modulated by Collective Magnetization Reversal in Artificial Spin Ice

    Energy Technology Data Exchange (ETDEWEB)

    Jungfleisch, Matthias B.; Sklenar, Joseph; Ding, Junjia; Park, Jungsik; Pearson, John E.; Novosad, Valentine; Schiffer, Peter; Hoffmann, Axel

    2017-12-01

    Spin-torque ferromagnetic resonance arises in heavy metal-ferromagnet heterostructures when an alternating charge current is passed through the bilayer stack. The methodology to detect the resonance is based on the anisotropic magnetoresistance, which is the change in the electrical resistance due to different orientations of the magnetization. In connected networks of ferromagnetic nanowires, known as artificial spin ice, the magnetoresistance is rather complex owing to the underlying collective behavior of the geometrically frustrated magnetic domain structure. Here, we demonstrate spin-torque ferromagnetic resonance investigations in a square artificial spin-ice system and correlate our observations to magneto-transport measurements. The experimental findings are described using a simulation approach that highlights the importance of the correlated dynamics response of the magnetic system. Our results open the possibility of designing reconfigurable microwave oscillators and magnetoresistive devices based on connected networks of nanomagnets.

  10. Ion–Cyclotron Resonance Frequency Interval Dependence on the O ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... The frequency intervals in which O VI ions get in resonance with ion–cyclotron waves are calculated using the kinetic model, for the latest six values found in literature on O VI ion number densities in the 1.5–3 region of the NPCH. It is found that the common resonance interval is 1.5 kHz to 3 kHz.

  11. Ion–Cyclotron Resonance Frequency Interval Dependence on the O ...

    Indian Academy of Sciences (India)

    The frequency intervals in which O VI ions get in resonance with ion–cyclotron waves are calculated using the kinetic model, for the latest six values found in literature on O VI ion number densities in the 1.5–3 region of the NPCH. It is found that the common resonance interval is 1.5 kHz to 3 kHz. The -variations of wave ...

  12. Resonant Scattering by Magnetic Impurities as a Model for Spin Relaxation in Bilayer Graphene.

    Science.gov (United States)

    Kochan, Denis; Irmer, Susanne; Gmitra, Martin; Fabian, Jaroslav

    2015-11-06

    We propose that the observed spin relaxation in bilayer graphene is due to resonant scattering by magnetic impurities. We analyze a resonant scattering model due to adatoms on both dimer and nondimer sites, finding that only the former give narrow resonances at the charge neutrality point. Opposite to single-layer graphene, the measured spin-relaxation rate in the graphene bilayer increases with carrier density. Although it has been commonly argued that a different mechanism must be at play for the two structures, our model explains this behavior rather naturally in terms of different broadening scales for the same underlying resonant processes. Not only do our results-using robust and first-principles inspired parameters-agree with experiment, they also predict an experimentally testable sharp decrease of the spin-relaxation rate at high carrier densities.

  13. Application of magnetic resonance force microscopy cyclic adiabatic inversion for a single-spin measurement

    CERN Document Server

    Berman, G P; Chapline, G; Gurvitz, S A; Hammel, P C; Pelekhov, D V; Suter, A; Tsifrinovich, V I

    2003-01-01

    We consider the process of a single-spin measurement using magnetic resonance force microscopy (MRFM) with a cyclic adiabatic inversion (CAI). This technique is also important for different applications, including a measurement of a qubit state in quantum computation. The measurement takes place through the interaction of a single spin with a cantilever modelled by a quantum oscillator in a coherent state in a quasi-classical range of parameters. The entire system is treated rigorously within the framework of the Schroedinger equation. For a many-spin system our equations accurately describe conventional MRFM experiments involving CAI of the spin system. Our computer simulations of the quantum spin-cantilever dynamics show that the probability distribution for the cantilever position develops two asymmetric peaks with the total relative probabilities mainly dependent on the initial angle between the directions of the average spin and the effective magnetic field, in the rotating frame. We show that each of th...

  14. Methodological considerations of electron spin resonance spin trapping techniques for measuring reactive oxygen species generated from metal oxide nanomaterials.

    Science.gov (United States)

    Jeong, Min Sook; Yu, Kyeong-Nam; Chung, Hyun Hoon; Park, Soo Jin; Lee, Ah Young; Song, Mi Ryoung; Cho, Myung-Haing; Kim, Jun Sung

    2016-05-19

    Qualitative and quantitative analyses of reactive oxygen species (ROS) generated on the surfaces of nanomaterials are important for understanding their toxicity and toxic mechanisms, which are in turn beneficial for manufacturing more biocompatible nanomaterials in many industrial fields. Electron spin resonance (ESR) is a useful tool for detecting ROS formation. However, using this technique without first considering the physicochemical properties of nanomaterials and proper conditions of the spin trapping agent (such as incubation time) may lead to misinterpretation of the resulting data. In this report, we suggest methodological considerations for ESR as pertains to magnetism, sample preparation and proper incubation time with spin trapping agents. Based on our results, each spin trapping agent should be given the proper incubation time. For nanomaterials having magnetic properties, it is useful to remove these nanomaterials via centrifugation after reacting with spin trapping agents. Sonication for the purpose of sample dispersion and sample light exposure should be controlled during ESR in order to enhance the obtained ROS signal. This report will allow researchers to better design ESR spin trapping applications involving nanomaterials.

  15. Spin and charge thermopower of resonant tunneling diodes

    Energy Technology Data Exchange (ETDEWEB)

    Nicolau, Javier H.; Sánchez, David [Institute for Cross-Disciplinary Physics and Complex Systems IFISC (UIB-CSIC), E-07122 Palma de Mallorca (Spain)

    2014-03-17

    We investigate thermoelectric effects in quantum well systems. Using the scattering approach for coherent conductors, we calculate the thermocurrent and thermopower both in the spin-degenerate case and in the presence of giant Zeeman splitting due to magnetic interactions in the quantum well. We find that the thermoelectric current at linear response is maximal when the well level is aligned with the Fermi energy and is robust against thermal variations. Furthermore, our results show a spin voltage generation in response to the applied thermal bias, giving rise to large spin Seebeck effects tunable with external magnetic fields, quantum well tailoring, and background temperature.

  16. Frequency-difference-dependent stochastic resonance in neural systems

    Science.gov (United States)

    Guo, Daqing; Perc, Matjaž; Zhang, Yangsong; Xu, Peng; Yao, Dezhong

    2017-08-01

    Biological neurons receive multiple noisy oscillatory signals, and their dynamical response to the superposition of these signals is of fundamental importance for information processing in the brain. Here we study the response of neural systems to the weak envelope modulation signal, which is superimposed by two periodic signals with different frequencies. We show that stochastic resonance occurs at the beat frequency in neural systems at the single-neuron as well as the population level. The performance of this frequency-difference-dependent stochastic resonance is influenced by both the beat frequency and the two forcing frequencies. Compared to a single neuron, a population of neurons is more efficient in detecting the information carried by the weak envelope modulation signal at the beat frequency. Furthermore, an appropriate fine-tuning of the excitation-inhibition balance can further optimize the response of a neural ensemble to the superimposed signal. Our results thus introduce and provide insights into the generation and modulation mechanism of the frequency-difference-dependent stochastic resonance in neural systems.

  17. High-resolution magnetic resonance spectroscopy using a solid-state spin sensor

    Science.gov (United States)

    Glenn, David R.; Bucher, Dominik B.; Lee, Junghyun; Lukin, Mikhail D.; Park, Hongkun; Walsworth, Ronald L.

    2018-03-01

    Quantum systems that consist of solid-state electronic spins can be sensitive detectors of nuclear magnetic resonance (NMR) signals, particularly from very small samples. For example, nitrogen–vacancy centres in diamond have been used to record NMR signals from nanometre-scale samples, with sensitivity sufficient to detect the magnetic field produced by a single protein. However, the best reported spectral resolution for NMR of molecules using nitrogen–vacancy centres is about 100 hertz. This is insufficient to resolve the key spectral identifiers of molecular structure that are critical to NMR applications in chemistry, structural biology and materials research, such as scalar couplings (which require a resolution of less than ten hertz) and small chemical shifts (which require a resolution of around one part per million of the nuclear Larmor frequency). Conventional, inductively detected NMR can provide the necessary high spectral resolution, but its limited sensitivity typically requires millimetre-scale samples, precluding applications that involve smaller samples, such as picolitre-volume chemical analysis or correlated optical and NMR microscopy. Here we demonstrate a measurement technique that uses a solid-state spin sensor (a magnetometer) consisting of an ensemble of nitrogen–vacancy centres in combination with a narrowband synchronized readout protocol to obtain NMR spectral resolution of about one hertz. We use this technique to observe NMR scalar couplings in a micrometre-scale sample volume of approximately ten picolitres. We also use the ensemble of nitrogen–vacancy centres to apply NMR to thermally polarized nuclear spins and resolve chemical-shift spectra from small molecules. Our technique enables analytical NMR spectroscopy at the scale of single cells.

  18. Spins of adsorbed molecules investigated by the detection of Kondo resonance

    Science.gov (United States)

    Komeda, Tadahiro

    2014-12-01

    Surface magnetism has been one of the platforms to explore the magnetism in low dimensions. It is also a key component for the development of quantum information processes, which utilizes the spin degree of freedom. The Kondo resonance is a phenomenon that is caused by an interaction between an isolated spin and conduction electrons. First observed in the 1930s as an anomalous increase in the low-temperature resistance of metals embedded with magnetic atoms, the Kondo physics mainly studied the effects of bulk magnetic impurities in the resistivity. In the last 15 years it has undergone a revival by a scanning tunneling microscope (STM) which enables the measurement of the Kondo resonance at surfaces using an atomic scale point contact. The detection of the Kondo resonance can be a powerful tool to explore surface magnetism. In this article, I review recent studies of the surface spin of adsorbed molecules by the detection of the Kondo resonance. Researches on metal phthalocyanine (MPc) and porphyrin molecules will be examined. In addition, the Kondo resonance for double-decker lanthanoide Pc molecules will be discussed. Some of the double-decker Pc molecules show single-molecule magnet (SMM) behavior, which attracts attention as a material for electronic devices. For both classes, the ligand plays a crucial role in determining the parameters of the Kondo resonance, such as the Kondo temperature and the change of the shape from peak to Fano-dip. In addition, the spin in delocalized molecular orbital forms the Kondo resonance, which shows significant differences from the Kondo resonance formed by the metal spins. Since molecular orbital can be tuned in a flexible manner by the design of the molecule, the Kondo resonance formed by delocalized molecular orbital might expand the knowledge of this field.

  19. Spin pumping through a topological insulator probed by x-ray detected ferromagnetic resonance

    Science.gov (United States)

    Figueroa, A. I.; Baker, A. A.; Collins-McIntyre, L. J.; Hesjedal, T.; van der Laan, G.

    2016-02-01

    In the field of spintronics, the generation of a pure spin current (without macroscopic charge flow) through spin pumping of a ferromagnetic (FM) layer opens up the perspective of a new generation of dissipation-less devices. Microwave driven ferromagnetic resonance (FMR) can generate a pure spin current that enters adjacent layers, allowing for both magnetization reversal (through spin-transfer torque) and to probe spin coherence in non-magnetic materials. However, standard FMR is unable to probe multilayer dynamics directly, since the measurement averages over the contributions from the whole system. The synchrotron radiation-based technique of x-ray detected FMR (XFMR) offers an elegant solution to this drawback, giving access to element-, site-, and layer-specific dynamical measurements in heterostructures. In this work, we show how XFMR has provided unique information to understand spin pumping and spin transfer torque effects through a topological insulator (TI) layer in a pseudo-spin valve heterostructure. We demonstrate that TIs function as efficient spin sinks, while also allowing a limited dynamic coupling between ferromagnetic layers. These results shed new light on the spin dynamics of this novel class of materials, and suggest future directions for the development of room temperature TI-based spintronics.

  20. Spin effects on the cyclotron frequency for a Dirac electron

    OpenAIRE

    Salesi, Giovanni; Recami, Erasmo

    1998-01-01

    The Barut--Zanghi (BZ) theory can be regarded as the most satisfactory picture of a classical spinning electron and constitutes a natural "classical limit" of the Dirac equation. The BZ model has been analytically studied in some previous papers of ours in the case of free particles. By contrast, in this letter we consider the case of external fields, and a previously found equation of the motion is generalized for a non-free spin-1/2 particle. In the important case of a spinning charge in a ...

  1. 2-mm Band and X-band electron spin resonance and electron spin-echo investigations of some carbonaceous materials

    Energy Technology Data Exchange (ETDEWEB)

    Tsvetkov, Y.D.; Dzuba, S.A.; Gulin, V.I. [Institute of Chemical Kinetics and Combustion, Novosibirsk (Russian Federation)

    1993-12-31

    Argonne Premium coal samples were studied by using 2-mm band and X-band continuous-wave electron spin resonance (CW ESR) and X-band electron spin-echo (ESE) spectroscopy. The line widths and g factors (Lande g factor, spectroscopic splitting factor) were determined. The correlation between {Delta}g = g{sub {parallel}} - g{sub {perpendicular}} and the carbon content in coal samples was established. Paramagnetic centers in coals could be attributed to radicals with partial redistribution of spin density from polycyclic {pi}-system to peroxide-type structures. The degree of this redistribution depends on the degree of carbonization. Phase relaxation times, T{sub 2}, for these coals were determined by using ESE spectroscopy. 5 refs., 2 figs., 3 tabs.

  2. Hysteresis loops of spin-dependent electronic current in a paramagnetic resonant tunnelling diode

    International Nuclear Information System (INIS)

    Wójcik, P; Spisak, B J; Wołoszyn, M; Adamowski, J

    2012-01-01

    Nonlinear properties of the spin-dependent electronic transport through a semiconductor resonant tunnelling diode with a paramagnetic quantum well are considered. The spin-dependent Wigner–Poisson model of the electronic transport and the two-current Mott’s formula for the independent spin channels are applied to determine the current–voltage curves of the nanodevice. Two types of the electronic current hysteresis loops are found in the current–voltage characteristics for both the spin components of the electronic current. The physical interpretation of these two types of the electronic current hysteresis loops is given based on the analysis of the spin-dependent electron densities and the potential energy profiles. The differences between the current–voltage characteristics for both the spin components of the electronic current allow us to explore the changes of the spin polarization of the current for different electric fields and determine the influence of the electronic current hysteresis on the spin polarization of the current flowing through the paramagnetic resonant tunnelling diode. (paper)

  3. Switching effects and spin-valley Andreev resonant peak shifting in silicene superconductor

    Science.gov (United States)

    Soodchomshom, Bumned; Niyomsoot, Kittipong; Pattrawutthiwong, Eakkarat

    2018-03-01

    The magnetoresistance and spin-valley transport properties in a silicene-based NM/FB/SC junction are investigated, where NM, FB and SC are normal, ferromagnetic and s-wave superconducting silicene, respectively. In the FB region, perpendicular electric and staggered exchange fields are applied. The quasiparticles may be described by Dirac Bogoliubov-de Gennes equation due to Cooper pairs formed by spin-valley massive fermions. The spin-valley conductances are calculated based on the modified Blonder-Tinkham-Klapwijk formalism. We find the spin-valley dependent Andreev resonant peaks in the junction shifted by applying exchange field. Perfect conductance switch generated by interplay of intrinsic spin orbit interaction and superconducting gap has been predicted. Spin and valley polarizations are almost linearly dependent on biased voltage near zero bias and then turn into perfect switch at biased voltage approaching the superconducting gap. The perfect switching of large magnetoresistance has been also predicted at biased energy near the superconducting gap. These switching effects may be due to the presence of spin-valley Andreev resonant peak near the superconducting gap. Our work reveals potential of silicene as applications of electronic switching devices and linear control of spin and valley polarizations.

  4. Interpretation of resonance frequencies recorded during hydraulic fracturing treatments

    Science.gov (United States)

    Tary, J. B.; van der Baan, M.; Eaton, D. W.

    2014-02-01

    Hydraulic fracturing treatments are often monitored by strings of geophones deployed in boreholes. Instead of picking discrete events only, we here use time-frequency representations of continuous recordings to identify resonances in two case studies. This paper outlines an interpretational procedure to identify their cause using a subdivision into source, path, and receiver-side effects. For the first case study, two main resonances are observed both at depth by the downhole geophones and on the surface by two broadband arrays. The two acquisition networks have different receiver and path effects, yet recorded the same resonances; these resonances are therefore likely generated by source effects. The amplitude pattern at the surface arrays indicates that these resonances are probably due to pumping operations. In the second case study, selective resonances are detected by the downhole geophones. Resonances coming from receiver effects are either lower or higher frequency, and wave propagation modeling shows that path effects are not significant. We identify two possible causes within the source area, namely, eigenvibrations of fractures or non-Darcian flow within the hydraulic fractures. In the first situation, 15-30 m long fluid-filled cracks could generate the observed resonances. An interconnected fracture network would then be required, corresponding to mesoscale deformation of the reservoir. Alternatively, systematic patterns in non-Darcian fluid flow within the hydraulic fracture could also be their leading cause. Resonances can be used to gain a better understanding of reservoir deformations or dynamic fluid flow perturbations during fluid injection into hydrocarbon and geothermal reservoirs, CO2 sequestration, or volcanic eruptions.

  5. Magnetic phase transitions in ferrite nanoparticles characterized by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Arias, Yesica, E-mail: yeika01@hotmail.com; Vázquez-Victorio, Gabriela; Ortega-Zempoalteca, Raul; Acevedo-Salas, Ulises; Valenzuela, Raul [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México D.F. 04510 (Mexico); Ammar, Souad [Laboratoires ITODYS, Université de Paris-Diderot, PRES Sorbonne Paris Cité, CNRS-UMR 7086, 75205 Paris Cedex (France)

    2015-05-07

    Ferrite magnetic nanoparticles in the composition Zn{sub 0.7}Ni{sub 0.3}Fe{sub 2}O{sub 4} were synthesized by the polyol method, with an average size of 8 nm. Electron spin resonance (ESR) measurements were carried out at a frequency of 9.45 GHz in the 100–500 K temperature range. Obtained results exhibited a characteristic ESR signal in terms of resonance field, H{sub res}, linewidth, ΔH, and peak ratio, R, for each magnetic phase. At low temperatures, the ferrimagnetic phase showed low H{sub res}, broad ΔH, and asymmetric R. At high temperatures, these parameters exhibited opposite values: high H{sub res}, small ΔH, and R ∼ 1. For intermediate temperatures, a different phase was observed, which was identified as a superparamagnetic phase by means of zero-field cooling-field cooling and hysteresis loops measurements. The observed differences were explained in terms of the internal fields and especially due to the cubic anisotropy in the ordered phase.

  6. Electron spin resonance spectroscopy of high purity crystals at millikelvin temperatures

    Science.gov (United States)

    Farr, Warrick G.; Creedon, Daniel L.; Goryachev, Maxim; Benmessai, Karim; Tobar, Michael E.

    2013-12-01

    Progress in the emerging field of engineered quantum systems requires the development of devices that can act as quantum memories. The realisation of such devices by doping solid state cavities with paramagnetic ions imposes a trade-off between ion concentration and cavity coherence time. Here, we investigate an alternative approach involving interactions between photons and naturally occurring impurity ions in ultra-pure crystalline microwave cavities exhibiting exceptionally high quality factors. We implement a hybrid Whispering Gallery/Electron Spin Resonance method to perform rigorous spectroscopy of an undoped single-crystal sapphire resonator over the frequency range 8{19 GHz, and at external applied DC magnetic fields up to 0.9 T. Measurements of a high purity sapphire cooled close to 100 mK reveal the presence of Fe3+, Cr3+, and V2+ impurities. A host of electron transitions are measured and identified, including the two-photon classically forbidden quadrupole transition (Δms = 2) for Fe3+, as well as hyperfine transitions of V2+.

  7. Experimental characterization of graphene by electrostatic resonance frequency tuning

    NARCIS (Netherlands)

    Sajadi, B.; Alijani, F.; Davidovikj, D.; Goosen, J.F.L.; Steeneken, P.G.; van Keulen, A.

    2017-01-01

    In the last decade, graphene membranes have drawn tremendous attention due to their potential application in Nano-Electro-Mechanical Systems. In this paper, we show that the frequency response curves of graphene resonators are powerful tools for their dynamic characterization and for extracting

  8. Wide Frequency Band Active Damping Strategy for DFIG System High Frequency Resonance

    DEFF Research Database (Denmark)

    Song, Yipeng; Blaabjerg, Frede

    2016-01-01

    As a popular renewable power generation solution, the Doubly Fed Induction Generator (DFIG) based wind power system may suffer from High Frequency Resonance (HFR) caused by the impedance interaction between the DFIG system and the parallel compensated weak network. A wide frequency band active...... damping strategy for DFIG system HFR, including a high-pass filter and a virtual resistance, is proposed in this paper. The advantages of this active damping strategy are, 1) no resonance frequency detection unit is required, thus the control complexity can be decreased; 2) no active damping parameters...

  9. Solid-state nuclear-spin quantum computer based on magnetic resonance force microscopy

    International Nuclear Information System (INIS)

    Berman, G. P.; Doolen, G. D.; Hammel, P. C.; Tsifrinovich, V. I.

    2000-01-01

    We propose a nuclear-spin quantum computer based on magnetic resonance force microscopy (MRFM). It is shown that an MRFM single-electron spin measurement provides three essential requirements for quantum computation in solids: (a) preparation of the ground state, (b) one- and two-qubit quantum logic gates, and (c) a measurement of the final state. The proposed quantum computer can operate at temperatures up to 1 K. (c) 2000 The American Physical Society

  10. The Spin Structure of the Proton in the Resonance Region

    Energy Technology Data Exchange (ETDEWEB)

    Fatemi, Renee H. [Univ. of Virginia, Charlottesville, VA (United States)

    2002-01-01

    Inclusive double spin asymmetries have been measured for $\\vec{p}$($\\vec{e}$,e') using the CLAS detector and a polarized 15NH3 target at Jefferson Lab in 1998. The virtual photon asymmetry A1, the longitudinal spin structure function, g1 (x, Q2), and the first moment Γ$1\\atop{p}$, have been extracted for a Q2 range of 0.15-2.0 GeV2. These results provide insight into the low Q2 evolution of spin dependent asymmetries and structure functions as well as the transition of Γ$1\\atop{p}$ from the photon point, where the Gerasimov, Drell and Hearn Sum Rule is expected to be satisfied, to the deep inelastic region.

  11. Outer hair cell piezoelectricity: frequency response enhancement and resonance behavior.

    Science.gov (United States)

    Weitzel, Erik K; Tasker, Ron; Brownell, William E

    2003-09-01

    Stretching or compressing an outer hair cell alters its membrane potential and, conversely, changing the electrical potential alters its length. This bi-directional energy conversion takes place in the cell's lateral wall and resembles the direct and converse piezoelectric effects both qualitatively and quantitatively. A piezoelectric model of the lateral wall has been developed that is based on the electrical and material parameters of the lateral wall. An equivalent circuit for the outer hair cell that includes piezoelectricity shows a greater admittance at high frequencies than one containing only membrane resistance and capacitance. The model also predicts resonance at ultrasonic frequencies that is inversely proportional to cell length. These features suggest all mammals use outer hair cell piezoelectricity to support the high-frequency receptor potentials that drive electromotility. It is also possible that members of some mammalian orders use outer hair cell piezoelectric resonance in detecting species-specific vocalizations.

  12. Radio-frequency association of molecules: an assisted Feshbach resonance

    Science.gov (United States)

    Beaufils, Q.; Crubellier, A.; Zanon, T.; Laburthe-Tolra, B.; Maréchal, É.; Vernac, L.; Gorceix, O.

    2010-01-01

    We develop a theoretical model to describe the radio-frequency (rf) induced coupling of a pair of colliding atoms to a Feshbach molecule when a magnetic field arbitrarily far from the Feshbach resonance is modulated in time. We use the dressed atom picture, and show that the coupling strength in presence of rf is equal to the Feshbach coupling strength multiplied by the square of a Bessel function. The argument of this function is equal to the ratio of the atomic rf Rabi frequency to the rf frequency. We experimentally demonstrate this law by measuring the rate of rf-association of molecules using a Feshbach resonance in d wave collisions between ultra-cold chromium atoms.

  13. Electron spin resonance of Gd in the nuclear cooling agent: PrNi5 single crystals

    International Nuclear Information System (INIS)

    Levin, R.; Davidov, D.; Grayevsky, A.; Shaltiel, D.; Zevin, V.

    1980-01-01

    The ESR of Gd in single crystals of PrNi 5 is observed to exhibit significant angular dependence of the resonance position and linewidth at low temperatures. This is interpreted in terms of the axial spin Hamiltonian which takes the anisotropic susceptibility and the Gd-Pr exchange into consideration. From lineshape analysis the axial crystal field parameter and isotropic Gd-Pr exchange are derived. The Gd ESR linewidth increases with temperature; the thermal broadening is angularly dependent. This is similar to that observed for the Pr NMR in PrNi 5 single crystals. Both the NMR and ESR thermal broadenings are attributed to low-frequency fluctuations of the Pr ions induced by the Pr-Pr exchange coupling. A model for hexagonal Van-Vleck compounds is given and with the linewidth enables the Pr-Pr exchange coupling, under the assumption of a Gaussian or a Lorenzian distribution of the low-frequency fluctuation spectra, to be extracted. It is suggested that the angular dependence of the ESR thermal broadening is due to the Gd-Pr exchange coupling. (UK)

  14. Spin measurements for 147Sm+n resonances: Further evidence for nonstatistical effects

    International Nuclear Information System (INIS)

    Koehler, P. E.; Ullmann, J. L.; Bredeweg, T. A.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R. S.; Vieira, D. J.; Wouters, J. M.

    2007-01-01

    We have determined the spins J of resonances in the 147 Sm(n,γ) reaction by measuring multiplicities of γ-ray cascades following neutron capture. Using this technique, we were able to determine J values for all but 14 of the 141 known resonances below E n =1 keV, including 41 firm J assignments for resonances whose spins previously were either unknown or tentative. These new spin assignments, together with previously determined resonance parameters, allowed us to extract level spacings (D 0,3 =11.76±0.93 and D 0,4 =11.21±0.85 eV) and neutron strength functions (10 4 S 0,3 =4.70±0.91 and 10 4 S 0,4 =4.93±0.92) for J=3 and 4 resonances, respectively. Furthermore, cumulative numbers of resonances and cumulative reduced neutron widths as functions of resonance energy indicate that very few resonances of either spin have been missed below E n =700 eV. This conclusion is strengthened by the facts that, over this energy range, Wigner distributions calculated using these D 0 values agree with the measured nearest-neighbor level spacings to within the experimental uncertainties, and that the Δ 3 values calculated from the data also agree with the expected values. Because a nonstatistical effect recently was reported near E n =350 eV from an analysis of 147 Sm(n,α) data, we divided the data into two regions; 0 n n n 0 distribution for resonances below 350 eV is consistent with the expected Porter-Thomas distribution. However, we found that Γ n 0 data in the 350 n 2 distribution having ν≥2 We discuss possible explanations for these observed nonstatistical effects and their possible relation to similar effects previously observed in other nuclides

  15. An efficient digital phase sensitive detector for use in electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Vistnes, A.I; Wormald, D.I.; Isachsen, S.

    1983-10-01

    A digital sensitive detector for a modified Bruker electron spin resonance spectrometer, equipped with an Aspect 2000 minicomputer, is described. Magnetic field modulation is derived from a clock in the computer, which makes it possible to perform the data acquisition fully synchronously with the modulation. The resulting high phase accuracy makes it possible to compress the data to a single modulation period before the Fourier transformation. Both the in-phase and the phase-quadrature signals (of the first or second harmonic) are recorded simultaneously. The system makes the data processing, including the Fourier transformation, approximately 1000 times faster than previously reported digital phase sensitive detector systems for electron spin resonance spectrometers

  16. Comprehensive high frequency electron paramagnetic resonance studies of single molecule magnets

    Science.gov (United States)

    Lawrence, Jonathan D.

    This dissertation presents research on a number of single molecule magnet (SMM) compounds conducted using high frequency, low temperature magnetic resonance spectroscopy of single crystals. By developing a new technique that incorporated other devices such as a piezoelectric transducer or Hall magnetometer with our high frequency microwaves, we were able to collect unique measurements on SMMs. This class of materials, which possess a negative, axial anisotropy barrier, exhibit unique magnetic properties such as quantum tunneling of a large magnetic moment vector. There are a number of spin Hamiltonians used to model these systems, the most common one being the giant spin approximation. Work done on two nickel systems with identical symmetry and microenvironments indicates that this model can contain terms that lack any physical significance. In this case, one must turn to a coupled single ion approach to model the system. This provides information on the nature of the exchange interactions between the constituent ions of the molecule. Additional studies on two similar cobalt systems show that, for these compounds, one must use a coupled single ion approach since the assumptions of the giant spin model are no longer valid. Finally, we conducted a collection of studies on the most famous SMM, Mn12Ac. Three different techniques were used to study magnetization dynamics in this system: stand-alone HFEPR in two different magnetization relaxation regimes, HFEPR combined with magnetometry, and HFEPR combined with surface acoustic waves. All of this research gives insight into the relaxation mechanisms in Mn12Ac.

  17. Dynamic detection of spin accumulation in ferromagnet-semiconductor devices by ferromagnetic resonance (Conference Presentation)

    Science.gov (United States)

    Crowell, Paul A.; Liu, Changjiang; Patel, Sahil; Peterson, Tim; Geppert, Chad C.; Christie, Kevin; Stecklein, Gordon; Palmstrøm, Chris J.

    2016-10-01

    A distinguishing feature of spin accumulation in ferromagnet-semiconductor devices is its precession in a magnetic field. This is the basis for detection techniques such as the Hanle effect, but these approaches become ineffective as the spin lifetime in the semiconductor decreases. For this reason, no electrical Hanle measurement has been demonstrated in GaAs at room temperature. We show here that by forcing the magnetization in the ferromagnet to precess at resonance instead of relying only on the Larmor precession of the spin accumulation in the semiconductor, an electrically generated spin accumulation can be detected up to 300 K. The injection bias and temperature dependence of the measured spin signal agree with those obtained using traditional methods. We further show that this new approach enables a measurement of short spin lifetimes (C. Liu, S. J. Patel, T. A. Peterson, C. C. Geppert, K. D. Christie, C. J. Palmstrøm, and P. A. Crowell, "Dynamic detection of electron spin accumulation in ferromagnet-semiconductor devices by ferromagnetic resonance," Nature Communications 7, 10296 (2016). http://dx.doi.org/10.1038/ncomms10296

  18. Influence of simulated bone-implant contact and implant diameter on secondary stability: a resonance frequency in vitro study.

    Science.gov (United States)

    Veltri, Mario; González-Martín, Oscar; Belser, Urs C

    2014-08-01

    This study tested the hypothesis of no differences in resonance frequency for standardized amounts of simulated bone-implant contact around implants with different diameters. In addition, it was evaluated if resonance frequency is able to detect a difference between stable and rotation mobile ("spinning") implants. Implants with diameters of 3.3, 4.1 and 4.8 mm were placed in a purposely designed metal mould where liquid polyurethane resin was then poured to obtain a simulated bone-implant specimen. By regulating the mould, it was possible to create the following simulated bone-implant contact groups: 3.3 mm (198.6 mm(2)); 4.1 mm (198.8 mm(2)); 4.8 mm (200.2 mm(2)); 4.8 mm (231.7 mm(2)); 4.8 mm (294.7 mm(2)). Each group included 10 specimens. After resin setting, resonance frequency was measured. On the last group, measurements were repeated after establishing implant rotational mobility. One-way ANOVA tests with post hoc comparisons, a Pearson's correlation coefficient and a t-test for repeated measurements were used to evaluate statistically significant differences. Implants with different diameters but with the same amount of simulated osseointegration revealed no differences in resonance frequency. On the contrary, an increase of simulated bone-implant contact resulted in significantly higher resonance frequency. A clear direct linear correlation resulted between resonance frequency and simulated bone-implant contact. Furthermore, a significant difference resulted between resonance frequency measured before and after creation of rotational mobility. Within the conditions of this study, the secondary stability was correlated with the simulated bone-implant contact. In addition, resonance frequency was able to discern between stable and rotation mobile implants. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Optimised frequency modulation for continuous-wave optical magnetic resonance sensing using nitrogen-vacancy ensembles.

    Science.gov (United States)

    El-Ella, Haitham A R; Ahmadi, Sepehr; Wojciechowski, Adam M; Huck, Alexander; Andersen, Ulrik L

    2017-06-26

    Magnetometers based on ensembles of nitrogen-vacancy centres are a promising platform for continuously sensing static and low-frequency magnetic fields. Their combination with phase-sensitive (lock-in) detection creates a highly versatile sensor with a sensitivity that is proportional to the derivative of the optical magnetic resonance lock-in spectrum, which is in turn dependant on the lock-in modulation parameters. Here we study the dependence of the lock-in spectral slope on the modulation of the spin-driving microwave field. Given the presence of the intrinsic nitrogen hyperfine spin transitions, we experimentally show that when the ratio between the hyperfine linewidth and their separation is ≳ 1/4, square-wave based frequency modulation generates the steepest slope at modulation depths exceeding the separation of the hyperfine lines, compared to sine-wave based modulation. We formulate a model for calculating lock-in spectra which shows excellent agreement with our experiments, and which shows that an optimum slope is achieved when the linewidth/separation ratio is ≲ 1/4 and the modulation depth is less then the resonance linewidth, irrespective of the modulation function used.

  20. Electron spin resonance of Fe4+ in amethyst quartz

    International Nuclear Information System (INIS)

    Cox, R.T.

    1975-01-01

    The ESR spectrum of Fe 4+ was looked for in amethyst quartz. Besides saturated Fe 3+ lines, ESR lines of a new paramagnetic center whose spin-lattice relaxation time is relatively short were observed. They could be attributed to Fe 4+ [fr

  1. PT -symmetric spectral singularity and negative-frequency resonance

    Science.gov (United States)

    Pendharker, Sarang; Guo, Yu; Khosravi, Farhad; Jacob, Zubin

    2017-03-01

    Vacuum consists of a bath of balanced and symmetric positive- and negative-frequency fluctuations. Media in relative motion or accelerated observers can break this symmetry and preferentially amplify negative-frequency modes as in quantum Cherenkov radiation and Unruh radiation. Here, we show the existence of a universal negative-frequency-momentum mirror symmetry in the relativistic Lorentzian transformation for electromagnetic waves. We show the connection of our discovered symmetry to parity-time (PT ) symmetry in moving media and the resulting spectral singularity in vacuum fluctuation-related effects. We prove that this spectral singularity can occur in the case of two metallic plates in relative motion interacting through positive- and negative-frequency plasmonic fluctuations (negative-frequency resonance). Our work paves the way for understanding the role of PT -symmetric spectral singularities in amplifying fluctuations and motivates the search for PT symmetry in novel photonic systems.

  2. Fully Automated Quantum-Chemistry-Based Computation of Spin-Spin-Coupled Nuclear Magnetic Resonance Spectra.

    Science.gov (United States)

    Grimme, Stefan; Bannwarth, Christoph; Dohm, Sebastian; Hansen, Andreas; Pisarek, Jana; Pracht, Philipp; Seibert, Jakob; Neese, Frank

    2017-11-13

    We present a composite procedure for the quantum-chemical computation of spin-spin-coupled 1 H NMR spectra for general, flexible molecules in solution that is based on four main steps, namely conformer/rotamer ensemble (CRE) generation by the fast tight-binding method GFN-xTB and a newly developed search algorithm, computation of the relative free energies and NMR parameters, and solving the spin Hamiltonian. In this way the NMR-specific nuclear permutation problem is solved, and the correct spin symmetries are obtained. Energies, shielding constants, and spin-spin couplings are computed at state-of-the-art DFT levels with continuum solvation. A few (in)organic and transition-metal complexes are presented, and very good, unprecedented agreement between the theoretical and experimental spectra was achieved. The approach is routinely applicable to systems with up to 100-150 atoms and may open new avenues for the detailed (conformational) structure elucidation of, for example, natural products or drug molecules. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  3. Electron spin resonance studies of gamma irradiated saccharides. Etudes par resonance paramagnetique electronique de saccharides soumis a un rayonnement gamma

    Energy Technology Data Exchange (ETDEWEB)

    Raffi, J.; Thiery, C.; Battesti, C.; Agnel, J.P.; Triolet, J.; Vincent, P. (CEA Centre d' Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Physiologie Vegetale et Ecosystemes)

    1993-04-01

    The radiolysis mechanism of several saccharides was studied in order to understand the radiolysis mechanism of starches. Electron Spin Resonance first performed in powder state did not allow determination of the chemical structure of the induced radicals. The spin-trapping method combined with HPLC however, followed by ESR spectra analysis with the 'Voyons' simulation program was applied to the study of glucose, glucose oligomers and disaccharides. We were thus able to further our understanding of the radiolysis mechanism of starches. 2 tabs., 4 figs.

  4. Superthin resonator dye laser with THz intermode frequency separation

    International Nuclear Information System (INIS)

    Rudych, P D; Surovtsev, N V

    2014-01-01

    Two-color laser irradiation is considered an effective way to pump THz excitations for numerous scientific and applied goals. We present a design for convenient laser source with THz intermode frequency separation. The setup is based on dye laser with superthin resonator pumped by a subnanosecond pulse laser. It was proven that the superthin resonator dye laser is useful, possesses high stability and high energy conversion, and generates narrow laser modes. The ability of this laser to pump CARS processes for THz vibrations is demonstrated. (letter)

  5. A new Skyrme energy density functional for a better description of spin-isospin resonances

    Energy Technology Data Exchange (ETDEWEB)

    Roca-Maza, X., E-mail: xavier.roca.maza@mi.infn.it [Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sez. di Milano, via Celoria 16, 20133 Milano (Italy); Colò, G. [Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sez. di Milano, via Celoria 16, 20133 Milano (Italy); Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China); Cao, Li-Gang [Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China); School of Mathematics and Physics, North China Electric Power University, Beijing 102206 (China); State Key Laboratory of Theoretical Physics, ITP, Chinese Academy of Sciences, Beijing 100190 (China); National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou 730000 (China); Sagawa, H. [Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China); Center for Mathematics and Physics, University of Aizu, Aizu-Wakamatsu, Fukushima 965-8580 (Japan); RIKEN, Nishina Center, Wako, 351-0198 (Japan)

    2015-10-15

    A correct determination of the isospin and spin-isospin properties of the nuclear effective interaction should lead to an accurate description of the Gamow-Teller resonance (GT), the Spin Dipole Resonance (SDR), the Giant Dipole Resonance (GDR) or the Antianalog Giant Dipole Resonance (AGDR), among others. A new Skyrme energy density functional named SAMi is introduced with the aim of going a step forward in setting the bases for a more precise description of spin-isospin resonances [1, 2]. In addition, we will discuss some new features of our analysis on the AGDR in {sup 208}Pb [3] as compared with available experimental data on this resonance [4, 5, 6], and on the GDR [7]. Such study, guided by a simple yet physical pocket formula, has been developed by employing the so called SAMi-J family of systematically varied interactions. This set of interactions is compatible with experimental data for values of the symmetry energy at saturation J and slope parameter L falling in the ranges 31−33 MeV and 75−95 MeV, respectively.

  6. A MEMS coupled resonator for frequency filtering in air

    KAUST Repository

    Ilyas, Saad

    2018-02-03

    We present design, fabrication, and characterization of a mechanically coupled MEMS H resonator capable of performing simultaneous mechanical amplification and filtering in air. The device comprises of two doubly clamped polyimide microbeams joined through the middle by a coupling beam of the same size. The resonator is fabricated via a multi-layer surface micromachining process. A special fabrication process and device design is employed to enable operation in air and to achieve mechanical amplification of the output response. Moreover, mixed-frequency excitation is used to demonstrate a tunable wide band filter for low frequency applications. It is demonstrated that through the multi-source harmonic excitation and the operation in air, an improved band-pass filter with flat response and minimal ripples can be achieved.

  7. Optimizing pTILT perfusion imaging in the presence of off-resonance frequency.

    Science.gov (United States)

    Ouyang, Cheng; Sutton, Bradley P

    2013-07-01

    To optimize the perfusion measurements and to recover loss of tagging efficiency from the blood flow measurements in the presence of static field inhomogeneity with the pseudo-continuous arterial spin labeling technique of pTILT, which is sensitive to off-resonance effects due to the employment of concatenated radiofrequency (RF) pulses for labeling. Numerical Bloch simulations were performed to explore the labeling responses of concatenated RF pulses (45°, ±45°) in pTILT as a function of off-resonance frequency. A correction method was proposed by curve-fitting the measured blood flow signal to the signal model obtained from the simulations. The performance of the proposed correction method was examined for three healthy subjects on a 3 Tesla magnet after good shimming as well as under a "worst-case" scenario with deliberate mis-shimming. In cases after good shimming, in which the off-resonance frequency was less than 50 Hz, the perfusion measurements by the optimized pTILT sequence were improved by 12.7% compared with the original pTILT. With a "worst-case" mis-shimming and frequency offset by 80 Hz, the blood flow signal was increased by 68.9% and 64.8% for optimized global and localized pTILT, respectively. Addressing the impact of off-resonance frequency on concatenated RF pulses, tagging efficiency can be effectively recovered in pTILT perfusion measurements. This strategy may be extended to other applications of concatenated RF pulses where sensitivity to magnetic field inhomogeneity prevents accurate quantification. Copyright © 2013 Wiley Periodicals, Inc.

  8. High-frequency microstrip cross resonators for circular polarization electron paramagnetic resonance spectroscopy.

    Science.gov (United States)

    Henderson, J J; Ramsey, C M; Quddusi, H M; del Barco, E

    2008-07-01

    In this article we discuss the design and implementation of a novel microstrip resonator which allows absolute control of the microwaves polarization degree for frequencies up to 30 GHz. The sensor is composed of two half-wavelength microstrip line resonators, designed to match the 50 Omega impedance of the lines on a high dielectric constant GaAs substrate. The line resonators cross each other perpendicularly through their centers, forming a cross. Microstrip feed lines are coupled through small gaps to three arms of the cross to connect the resonator to the excitation ports. The control of the relative magnitude and phase between the two microwave stimuli at the input ports of each line allows for tuning the degree and type of polarization of the microwave excitation at the center of the cross resonator. The third (output) port is used to measure the transmitted signal, which is crucial to work at low temperatures, where reflections along lengthy coaxial lines mask the signal reflected by the resonator. Electron paramagnetic resonance spectra recorded at low temperature in an S=5/2 molecular magnet system show that 82% fidelity circular polarization of the microwaves is achieved over the central area of the resonator.

  9. Optical frequency comb generation from aluminum nitride microring resonator.

    Science.gov (United States)

    Jung, Hojoong; Xiong, Chi; Fong, King Y; Zhang, Xufeng; Tang, Hong X

    2013-08-01

    Aluminum nitride (AlN) is an appealing nonlinear optical material for on-chip wavelength conversion. Here we report optical frequency comb generation from high-quality-factor AlN microring resonators integrated on silicon substrates. By engineering the waveguide structure to achieve near-zero dispersion at telecommunication wavelengths and optimizing the phase matching for four-wave mixing, frequency combs are generated with a single-wavelength continuous-wave pump laser. Further, the Kerr coefficient (n₂) of AlN is extracted from our experimental results.

  10. Optimizations of ozone generator at low resonance frequency

    Science.gov (United States)

    Garamoon, A. A.; Elakshar, F. F.; Elsawah, M.

    2009-11-01

    The effect of the frequency on the different parameters of ozone generation in the dielectric barrier discharge (DBD) has been investigated. It is found that at low frequency, (f0 = 325 Hz), an electric resonance can be obtained in the electric circuit. The onset voltage, at which the ozone starts to build up, was reduced from 3.25 kV at 50 Hz to 1.57 kV at 325 Hz. The efficiency has been increased from nearly zero at 50 Hz to 232.94 g/kW h at 200 Hz under applied voltage of 2.025 kV. in here

  11. Exchange interaction and rashba spin splitting effects in electron spin resonance in narrow-gap quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Krishtopenko, S. S. [Institute for Physics of Microstructures RAS, GSP-105, 603950, Nizhny Novgorod, Russia and Laboratoire National des Champs Magnétiques Intenses (LNCMI-T), CNRS UPR 3228 Université de Toulouse, 143 Avenue de Rangueil, F-31400 Toulouse (France); Malyzhenkov, A. V.; Kalinin, K. P.; Ikonnikov, A. V.; Maremyanin, K. V.; Gavrilenko, V. I. [Institute for Physics of Microstructures RAS, GSP-105, 603950, Nizhny Novgorod (Russian Federation); Goiran, M. [Laboratoire National des Champs Magnétiques Intenses (LNCMI-T), CNRS UPR 3228 Université de Toulouse, 143 Avenue de Rangueil, F-31400 Toulouse (France)

    2013-12-04

    We report a study of electron spin resonance (ESR) in a perpendicular magnetic field in n-type narrow-gap quantum well (QW) heterostructures. Using the Hartree-Fock approximation, based on the 8×8 k⋅p Hamiltonian, the many-body corrections to the ESR energy are found to be nonzero in symmetric and asymmetric narrow-gap QWs. We demonstrate a significant enhancement of the ESR energy in asymmetric QWs, induced by the Rashba spin splitting and exchange interaction, as well as the exchange-induced enhancement of the ESR energy in symmetric QWs. The ESR energies estimated for 2DEG in InAs/AlSb QWs are compared with experimental results in weak magnetic fields.

  12. Resonance induced spin-selective transport behavior in carbon nanoribbon/nanotube/nanoribbon heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiang-Hua [School of Physics and Microelectronics Science, Hunan University, Changsha 410082 (China); Department of Electrical and Information Engineering, Hunan Institute of Engineering, Xiangtan 411101 (China); Wang, Ling-Ling, E-mail: llwang@hnu.edu.cn [School of Physics and Microelectronics Science, Hunan University, Changsha 410082 (China); Li, Xiao-Fei, E-mail: xf.li@uestc.edu.cn [School of Physics and Microelectronics Science, Hunan University, Changsha 410082 (China); School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Chen, Tong; Li, Quan [School of Physics and Microelectronics Science, Hunan University, Changsha 410082 (China)

    2015-09-04

    Carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) are attractive in spintronics. Here, we propose GNR/CNT/GNR heterojunctions constructed by attaching zigzag-GNRs at the side-wall of CNT for spintronic devices. The thermal stability and electronic transport properties were explored using ab initio molecular dynamics simulations and nonequilibrium Green's function methods, respectively. Results demonstrate that the sp{sup 3}-hybridized contacts formed at the interface assure a good thermal stability of the system and make the CNT to be regarded as resonator. Only the electron of one spin-orientation and resonant energy is allowed to transport, resulting in the remarkable spin-selective transport behavior at the ferromagnetic state. - Highlights: • The new mechanism for spin-selective transport in molecular junction is proposed. • The two sp{sup 3} contacts formed between CNT and GNR can be regarded as electronic isolators. • The two isolators make the CNT act as a resonator. • Only the electron of one spin-orientation and resonant energy can form standing wave and transport through the whole junction.

  13. Phosphorus-doped thin silica films characterized by magic-angle spinning nuclear magnetic resonance spectroscopy

    DEFF Research Database (Denmark)

    Jacobsen, H.J.; Skibsted, J.; Kristensen, Martin

    2001-01-01

    Magic-angle spinning nuclear magnetic resonance spectra of 31P and 29Si have been achieved for a thin silica film doped with only 1.8% 31P and deposited by plasma enhanced chemical vapor deposition on a pure silicon wafer. The observation of a symmetric 31P chemical shift tensor is consistent...

  14. Can we learn about the spin-flip giant dipole resonances with pions

    International Nuclear Information System (INIS)

    Baer, H.W.

    1982-01-01

    Data and calculations for the 40 Ca(π+-,π 0 ) reactions at 164 MeV are shown which indicate that pion scattering possesses a unique signature for separately identifying the 1 - and 2 - spin-isospin components of the giant dipole resonance

  15. Resonance induced spin-selective transport behavior in carbon nanoribbon/nanotube/nanoribbon heterojunctions

    International Nuclear Information System (INIS)

    Zhang, Xiang-Hua; Wang, Ling-Ling; Li, Xiao-Fei; Chen, Tong; Li, Quan

    2015-01-01

    Carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) are attractive in spintronics. Here, we propose GNR/CNT/GNR heterojunctions constructed by attaching zigzag-GNRs at the side-wall of CNT for spintronic devices. The thermal stability and electronic transport properties were explored using ab initio molecular dynamics simulations and nonequilibrium Green's function methods, respectively. Results demonstrate that the sp 3 -hybridized contacts formed at the interface assure a good thermal stability of the system and make the CNT to be regarded as resonator. Only the electron of one spin-orientation and resonant energy is allowed to transport, resulting in the remarkable spin-selective transport behavior at the ferromagnetic state. - Highlights: • The new mechanism for spin-selective transport in molecular junction is proposed. • The two sp 3 contacts formed between CNT and GNR can be regarded as electronic isolators. • The two isolators make the CNT act as a resonator. • Only the electron of one spin-orientation and resonant energy can form standing wave and transport through the whole junction

  16. On the spin and parity of a single-produced resonance at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Bolognesi, Sara; Gao, Yanyan; Gritsan, Andrei V.; Melnikov, Kirill; Schulze, Markus; Tran, Nhan V.; Whitbeck, Andrew

    2012-11-01

    The experimental determination of the properties of the newly discovered boson at the Large Hadron Collider is currently the most crucial task in high energy physics. We show how information about the spin, parity, and, more generally, the tensor structure of the boson couplings can be obtained by studying angular and mass distributions of events in which the resonance decays to pairs of gauge bosons, $ZZ, WW$, and $\\gamma \\gamma$. A complete Monte Carlo simulation of the process $pp \\to X \\to VV \\to 4f$ is performed and verified by comparing it to an analytic calculation of the decay amplitudes $X \\to VV \\to 4f$. Our studies account for all spin correlations and include general couplings of a spin $J=0,1,2$ resonance to Standard Model particles. We also discuss how to use angular and mass distributions of the resonance decay products for optimal background rejection. It is shown that by the end of the 8 TeV run of the LHC, it might be possible to separate extreme hypotheses of the spin and parity of the new boson with a confidence level of 99% or better for a wide range of models. We briefly discuss the feasibility of testing scenarios where the resonances is not a parity eigenstate.

  17. A point of view about identification of irradiated foods by electron spin resonance

    International Nuclear Information System (INIS)

    Saint-Lebe, L.; Raffi, J.

    1986-11-01

    Principles and conditions required for using electron spin resonance (ESR) in identifying irradiated foods are first put forth. After a literature review, examples of irradiated cereals and French prunes are described in order to derive general conclusions concerning the future of ESR in this field

  18. Temperature Regulating System for Use with an Electron Spin Resonance Spectrometer

    DEFF Research Database (Denmark)

    Fenger, J.

    1965-01-01

    A servosystem that controls the sample temperature in an electron spin resonance spectrometer is described. It is based upon the regulation of the combination of two nitrogen gas flows of different temperatures. The temperature can be preset with an accuracy to about 1 degC between -140 and 100°C...

  19. Resonant coherent quantum tunneling of the magnetization of spin-½ systems : Spin-parity effects

    NARCIS (Netherlands)

    García-Pablos, D.; García, N.; Raedt, H. De

    1997-01-01

    We perform quantum dynamical calculations to study the reversal of the magnetization for systems of a few spin-½ particles with a general biaxial anisotropy in the presence of an external magnetic field at T=0 and with no dissipation. Collective quantum tunneling of the magnetization is demonstrated

  20. An electron spin resonance (ESR) investigation of the dosimetric potential of potassium tartrate

    International Nuclear Information System (INIS)

    Korkmaz, G.; Oezsayin, F.; Polat, M.

    2012-01-01

    While unirradiated potassium tartrate (PT) samples do not exhibit any electron spin resonance signal, irradiated ones contain many resonance signals. A power function of the radiation dose was found to describe well the dose-response curve of the central resonance signal, and adjusting the microwave power and modulation amplitude to be 2 mW and 1 mT, respectively, was found to increase the sensitivity of PT. The radiation sensitivity of PT and the accuracy of the measured radiation dose were found to be G = 0.42 and 6%, respectively. (authors)

  1. Thermal mixing in multiple-pulse nuclear quadrupole resonance spin-locking

    International Nuclear Information System (INIS)

    Beltjukov, P A; Kibrik, G E; Furman, G B; Goren, S D

    2007-01-01

    We report on an experimental and theoretical nuclear quadrupole resonance (NQR) multiple-pulse spin-locking study of the thermal mixing process in solids containing nuclei of two different sorts, I>1/2 and S = 1/2, coupled by dipole-dipole interactions and influenced by an external magnetic field. Two coupled equations for the inverse spin temperatures of both the spin systems describing the mutual spin-lattice relaxation and the thermal mixing were obtained using the method of the nonequilibrium state operator. It is shown that the relaxation process is realized with non-exponential time dependence described by a sum of two exponents. The calculated relaxation time versus the multiple-pulse field parameters agrees well with the obtained experimental data in 1,4-dichloro-2-nitrobenzene. The calculated magnetization relaxation time versus the strength of the applied magnetic field agrees well with the obtained experimental data

  2. Radiation damping in ferromagnetic resonance induced by a conducting spin sink

    Science.gov (United States)

    Qaid, Mohammad M.; Richter, Tim; Müller, Alexander; Hauser, Christoph; Ballani, Camillo; Schmidt, Georg

    2017-11-01

    We have investigated the damping in the ferromagnetic resonance (FMR) of yttrium iron garnet (YIG) caused by spin pumping into adjacent conducting materials, namely, Pt and the conducting polymer poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS). By a systematic study which also includes multilayers in which the conducting layer is separated from YIG by an insulator, we can show that a considerable part of the damping can be attributed to the so-called radiation damping which originates from the interaction of the magnetic fields caused by the precessing magnetization with the conducting layer. Especially, when PEDOT:PSS is used as a spin sink, the observed damping must be attributed completely to radiation damping, and no contribution from spin pumping can be identified. These results demonstrate that the Gilbert damping as a measure of spin pumping can only be used when careful control experiments accompany the investigation.

  3. Introduction to Spin Label Electron Paramagnetic Resonance Spectroscopy of Proteins

    Science.gov (United States)

    Melanson, Michelle; Sood, Abha; Torok, Fanni; Torok, Marianna

    2013-01-01

    An undergraduate laboratory exercise is described to demonstrate the biochemical applications of electron paramagnetic resonance (EPR) spectroscopy. The beta93 cysteine residue of hemoglobin is labeled by the covalent binding of 3-maleimido-proxyl (5-MSL) and 2,2,5,5-tetramethyl-1-oxyl-3-methyl methanethiosulfonate (MTSL), respectively. The excess…

  4. Application of magnetic resonance force microscopy cyclic adiabatic inversion for a single-spin measurement

    International Nuclear Information System (INIS)

    Berman, G P; Borgonovi, F; Chapline, G; Gurvitz, S A; Hammel, P C; Pelekhov, D V; Suter, A; Tsifrinovich, V I

    2003-01-01

    We consider the process of a single-spin measurement using magnetic resonance force microscopy (MRFM) with a cyclic adiabatic inversion (CAI). This technique is also important for different applications, including a measurement of a qubit state in quantum computation. The measurement takes place through the interaction of a single spin with a cantilever modelled by a quantum oscillator in a coherent state in a quasi-classical range of parameters. The entire system is treated rigorously within the framework of the Schroedinger equation. For a many-spin system our equations accurately describe conventional MRFM experiments involving CAI of the spin system. Our computer simulations of the quantum spin-cantilever dynamics show that the probability distribution for the cantilever position develops two asymmetric peaks with the total relative probabilities mainly dependent on the initial angle between the directions of the average spin and the effective magnetic field, in the rotating frame. We show that each of the peaks is correlated with the direction of the average spin (being along or opposite to the direction of the effective magnetic field). This generates two possible outcomes of a single-spin measurement, similar to the Stern-Gerlach effect. We demonstrate that the generation of the second peak can be significantly suppressed by turning on adiabatically the amplitude of the rf magnetic field. We also show that MRFM CAI can be used both for detecting a signal from a single spin, and for measuring the single-spin state by measuring the phase of the cantilever driving oscillations

  5. Operation States Analysis of the Series-Parallel resonant Converter Working Above Resonance Frequency

    Directory of Open Access Journals (Sweden)

    Peter Dzurko

    2007-01-01

    Full Text Available Operation states analysis of a series-parallel converter working above resonance frequency is described in the paper. Principal equations are derived for individual operation states. On the basis of them the diagrams are made out. The diagrams give the complex image of the converter behaviour for individual circuit parameters. The waveforms may be utilised at designing the inverter individual parts.

  6. Full investigation of the resonant frequency servo loop for resonator fiber-optic gyro.

    Science.gov (United States)

    Ma, Huilian; Lu, Xiao; Yao, Linzhi; Yu, Xuhui; Jin, Zhonghe

    2012-07-20

    Resonator fiber-optic gyro (RFOG) is a high-accuracy inertial rotation sensor based on the Sagnac effect. A high-accuracy resonant frequency servo loop is indispensable for a high-performance RFOG. It is composed of a frequency discriminator, a loop filter, and a laser actuator. Influences of the loop parameters are fully developed. Optimized loop parameters are obtained by considering the noise reduction and wide dynamic performance of the RFOG. As a result, with the integration time of 10 s, the accuracy of the resonant frequency loop is increased to 0.02 Hz (1σ). It is equivalent to a rotation rate of 0.067°/h, which is close to the shot noise limit for the RFOG, while a minimum rotation of ±0.05°/s has been carried out simultaneously. These are the best results reported to date, to the best of our knowledge, for an RFOG using the miniature semiconductor laser that benefits from the optimization of the resonant frequency servo-loop parameters.

  7. Simulation of stress-modulated magnetization precession frequency in Heusler-based spin torque oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Houbing, E-mail: hbhuang@ustb.edu.cn; Zhao, Congpeng; Ma, Xingqiao, E-mail: xqma@sas.ustb.edu.cn

    2017-03-15

    We investigated stress-modulated magnetization precession frequency in Heusler-based spin transfer torque oscillator by combining micromagnetic simulations with phase field microelasticity theory, by encapsulating the magnetic tunnel junction into multilayers structures. We proposed a novel method of using an external stress to control the magnetization precession in spin torque oscillator instead of an external magnetic field. The stress-modulated magnetization precession frequency can be linearly modulated by externally applied uniaxial in-plane stress, with a tunable range 4.4–7.0 GHz under the stress of 10 MPa. By comparison, the out-of-plane stress imposes negligible influence on the precession frequency due to the large out-of-plane demagnetization field. The results offer new inspiration to the design of spin torque oscillator devices that simultaneously process high frequency, narrow output band, and tunable over a wide range of frequencies via external stress. - Highlights: • We proposed stress-modulated magnetization precession in spin torque oscillator. • The magnetization precession frequency can be linearly modulated by in-plane stress. • The stress also can widen the magnetization frequency range 4.4–7.0 GHz. • The stress-modulated oscillation frequency can simplify STO devices.

  8. Basic mode of nonlinear spin-wave resonance in normally magnetized ferrite films

    International Nuclear Information System (INIS)

    Gulyaev, Yu.V.; Zil'berman, P.E.; Timiryazev, A.G.; Tikhomirova, M.P.

    2000-01-01

    Modes of nonlinear and spin-wave resonance (SWR) in the normally magnetized ferrite films were studied both theoretically and experimentally. The particular emphasis was placed on the basic mode of SWR. One showed theoretically that with the growth of the precession amplitude the profile of the basic mode changed. The nonlinear shift of the resonance field depends on the parameters of fixing of the surface spins. Films of ferroyttrium garnet (FYG) with strong gradient of the single-axis anisotropy field along the film thickness, as well as, FYG films of the submicron thickness where investigated experimentally. With the intensification of Uhf-power one observed the sublinear shift of the basic mode resonance field following by the superlinear growth of the absorbed power. That kind of behaviour is explained by variation of the profile of the varying magnetization space distribution [ru

  9. Single-spin asymmetries of d({gamma},{pi})NN in the first resonance region

    Energy Technology Data Exchange (ETDEWEB)

    Darwish, Eed M. E-mail: eeddarwish@yahoo.com

    2004-04-19

    Incoherent photoproduction of pions on the deuteron in the first resonance region is investigated with special emphasis on single-spin asymmetries. For the elementary pion production operator an effective Lagrangian model which includes the standard pseudovector Born terms and a resonance contribution from the {delta}(1232)-excitation is used. Single-spin asymmetries, both for charged and neutral pion photoproduction on the deuteron, are analyzed and calculated in the first resonance region. The linear photon asymmetry {sigma}, vector target asymmetry T{sub 11} and tensor target asymmetries T{sub 20}, T{sub 21}, and T{sub 22} for the reaction d({gamma},{pi})NN with polarized photon beam and/or oriented deuteron target are predicted for forthcoming experiments.

  10. One-loop effects from spin-1 resonances in Composite Higgs models

    CERN Document Server

    Contino, Roberto

    2015-01-01

    We compute the 1-loop correction to the electroweak observables from spin-1 resonances in SO(5)/SO(4) composite Higgs models. The strong dynamics is modeled with an effective description comprising the Nambu-Goldstone bosons and the lowest-lying spin-1 resonances. A classification is performed of the relevant operators including custodially-breaking effects from the gauging of hypercharge. The 1-loop contribution of the resonances is extracted in a diagrammatic approach by matching to the low-energy theory of Nambu-Goldstone bosons. We find that the correction is numerically important in a significant fraction of the parameter space and tends to weaken the bounds providing a negative shift to the S parameter.

  11. Spin Resonance in Three-Dimensional Superconductors: The Case of CeCoIn5

    Science.gov (United States)

    Chubukov, A. V.; Gor'Kov, L. P.

    2008-10-01

    The recent observation of resonance spin excitation at (1/2, 1/2, 1/2) in the superconducting state of CeCoIn5 [C. Stock , Phys. Rev. Lett. 100, 087001 (2008)PRLTAO0031-900710.1103/PhysRevLett.100.087001] was interpreted as evidence for dx2-y2 gap symmetry, by analogy with cuprates. This is true if the resonance is a spin exciton. We argue that such a description is undermined by the three dimensionality of CeCoIn5. We show that in 3D systems the excitonic resonance only emerges at strong coupling, and is weak. We argue in favor of the alternative, magnon scenario, which does not require a dx2-y2 gap.

  12. Modal frequency degeneracy in thermally loaded optical resonators.

    Science.gov (United States)

    Bullington, Amber L; Lantz, Brian T; Fejer, Martin M; Byer, Robert L

    2008-05-20

    We observe power coupling from the fundamental mode to frequency-degenerate higher-order spatial modes in optical resonators illuminated with a 30 W laser. Thermally-induced modal frequency degeneracy facilitates power transfer from the fundamental mode to higher-order modes, reduces power coupling into the cavity, and triggers power fluctuations. Modeling thermoelastic deformation of a mirror's surface shows predicted modal frequency degeneracy to be in reasonable agreement with experimental observations. Predictions for the Laser Interferometer Gravitational-wave Observatory (LIGO) show that the circulating fundamental-mode power necessary for gravitational-wave detection is compromised at coating absorptions of 3.8 and 0.44 ppm for Enhanced and Advanced LIGO Fabry-Pérot cavities, respectively.

  13. Radio Frequency Interference Suppression for Landmine Detection by Quadrupole Resonance

    Science.gov (United States)

    Liu, Guoqing; Jiang, Yi; Xiong, Hong; Li, Jian; Barrall, Geoffrey A.

    2006-12-01

    The quadrupole resonance (QR) technology can be used as a confirming sensor for buried plastic landmine detection by detecting the explosives within the mine. We focus herein on the detection of TNT mines via the QR sensor. Since the frequency of the QR signal is located within the AM radio frequency band, the QR signal can be corrupted by strong radio frequency interferences (RFIs). Hence to detect the very weak QR signal, RFI mitigation is essential. Reference antennas, which receive RFIs only, can be used together with the main antenna, which receives both the QR signal and the RFIs, for RFI mitigation. The RFIs are usually colored both spatially and temporally, and hence exploiting only the spatial diversity of the antenna array may not give the best performance. We exploit herein both the spatial and temporal correlations of the RFIs to improve the TNT detection performance.

  14. Electron spin resonance of radicals and metal complexes

    International Nuclear Information System (INIS)

    1993-01-01

    The materials are a collection of extended synopsis of papers presented at the conference sessions. The broad area of magnetic techniques applications has been described as well as their spectra interpretation methods. The ESR, NMR, ENDOR and spin echo were applied for studying the radiation and UV induced radicals in chemical and biological systems. Also in the study of complexes of metallic ions (having the paramagnetic properties) and their interaction with the matrix, the magnetic techniques has been commonly used. They are also very convenient tool for the study of reaction kinetics and mechanism as well as interaction of paramagnetic species with themselves and crystal lattice or with the surface as for thee catalytic processes

  15. Resonant Frequency Monitoring at Mesa Arch, Canyonlands National Park

    Science.gov (United States)

    Dorsey, A.; Moore, J. R.; Thorne, M. S.; Culp, J.

    2014-12-01

    The national parks of southern Utah are home to a number of spectacular landmarks that draw visitors from across the world. However, there is currently no methodology in place to evaluate the structural health of these structures as they change through time or in the wake of a damaging event. Our study combines in-situ ambient vibration measurements with 3D numerical modeling to monitor the resonance characteristics of Mesa Arch, a prominent arch in Canyonlands National Park. We measure spectral and polarization attributes of ambient vibrations using two broadband seismometers: one placed on the arch and the other located at a distance of ~100 m for reference. Repeat measurements, ranging in duration from 1 hour to 3 days, are aimed at assessing short- and long-term changes in resonance characteristics, which in turn provide evidence of internal mechanical change. Numerical modal analysis, executed by inputting geometric and representative material properties of the arch into 3D modeling software, allows us to match the measured fundamental frequency as well as higher-order modes. Preliminary results suggest minor variations in resonant frequencies are predominantly controlled by thermal effects, i.e. changes in bulk material stiffness as the rock expands and contracts.

  16. Scattering resonances in a low-dimensional Rashba-Dresselhaus spin-orbit coupled quantum gas

    Science.gov (United States)

    Wang, Su-Ju; Blume, D.

    2017-04-01

    Confinement-induced resonances allow for the tuning of the effective one-dimensional coupling constant. When the scattering state associated with the ground transverse mode is brought into resonance with the bound state attached to the energetically excited transverse modes, the atoms interact through an infinitely strong repulsion. This provides a route to realize the Tonks-Girardeau gas. On the other hand, the realization of synthetic gauge fields in cold atomic systems has attracted a lot of attention. For instance, bound-state formation is found to be significantly modified in the presence of spin-orbit coupling in three dimensions. This motivates us to study ultracold collisions between two Rashba-Dresselhaus spin-orbit coupled atoms in a quasi-one-dimensional geometry. We develop a multi-channel scattering formalism that accounts for the external transverse confinement and the spin-orbit coupling terms. The interplay between these two single-particle terms is shown to give rise to new scattering resonances. In particular, it is analyzed what happens when the scattering energy crosses the various scattering thresholds that arise from the single-particle confinement and the spin-orbit coupling. Support by the NSF is gratefully acknowledged.

  17. Resonator Sensitivity Optimization in Magnetic Resonance and the Development of a Magic Angle Spinning Probe for the NMR Study of Rare Spin Nuclei on Catalytic Surfaces.

    Science.gov (United States)

    Doty, Francis David

    The sensitivity of an arbitrary resonator for the detection of a magnetic resonance signal is derived from basic energy considerations, and is shown to be dependent on V(,s)/t(,90)P(' 1/2). The radiation damping time constant is shown to be inversely dependent on the rf filling factor. Several resonators are analyzed in detail. The optimum solenoid is shown to have a length of about 1.5 times the diameter. The multilayer solenoid and the capacitively shortened slotted line resonator are shown to have advantages for samples with high dielectric losses. The capacitively shortened slotted line resonator is shown to substantially reduce acoustic ringing problems. Efficient methods are discussed for double and triple tuning these resonators. A slotted cylindrical resonator is described which gives higher sensitivity and faster response time than conventional cavities for very small samples at X-band ESR frequencies. Double tuned circuits using lumped elements are shown to be generally more efficient than those using transmission lines in generating rf fields. The optimum inductance ratio of the two coils in a ('13)C, ('1)H CP experiment is about 3. The high speed cylindrical sample spinner is analyzed in terms of compressible fluid dynamics, resonant modes, and structural analysis to arrive at optimum air bearing and spinner design recommendations. The optimum radial clearance is shown to depend on the 1/3 power of the rotor diameter. The required air bearing hole diameter has a square root dependence on the rotor diameter. Air pockets are shown to increase the resonant frequencies. Relevant data for a number of high strength insulators including hard ceramics are tabulated, and limiting speeds are calculated. CP MAS experiments on a 5% monolayer of n-butylamine absorbed on (gamma)-alumina reveal six lines. By comparison with the liquid phase spectrum it was determined that at least two types of chemically different surface species were present and that surface

  18. Resonance Frequency of Optical Microbubble Resonators: Direct Measurements and Mitigation of Fluctuations

    Directory of Open Access Journals (Sweden)

    Alessandro Cosci

    2016-08-01

    Full Text Available This work shows the improvements in the sensing capabilities and precision of an Optical Microbubble Resonator due to the introduction of an encaging poly(methyl methacrylate (PMMA box. A frequency fluctuation parameter σ was defined as a score of resonance stability and was evaluated in the presence and absence of the encaging system and in the case of air- or water-filling of the cavity. Furthermore, the noise interference introduced by the peristaltic and the syringe pumping system was studied. The measurements showed a reduction of σ in the presence of the encaging PMMA box and when the syringe pump was used as flowing system.

  19. Proximal Bright Vessel Sign on Arterial Spin Labeling Magnetic Resonance Imaging in Acute Cardioembolic Cerebral Infarction.

    Science.gov (United States)

    Kato, Ayumi; Shinohara, Yuki; Kuya, Keita; Sakamoto, Makoto; Kowa, Hisanori; Ogawa, Toshihide

    2017-07-01

    The congestion of spin-labeled blood at large-vessel occlusion can present as hyperintense signals on perfusion magnetic resonance imaging with 3-dimensional pseudo-continuous arterial spin labeling (proximal bright vessel sign). The purpose of this study was to clarify the difference between proximal bright vessel sign and susceptibility vessel sign in acute cardioembolic cerebral infarction. Forty-two patients with cardioembolic cerebral infarction in the anterior circulation territory underwent magnetic resonance imaging including diffusion-weighted imaging, 3-dimensional pseudo-continuous arterial spin labeling perfusion magnetic resonance imaging, T2*-weighted imaging, and 3-dimensional time-of-flight magnetic resonance angiography using a 3-T magnetic resonance scanner. Visual assessments of proximal bright vessel sign and the susceptibility vessel sign were performed by consensus of 2 experienced neuroradiologists. The relationship between these signs and the occlusion site of magnetic resonance angiography was also investigated. Among 42 patients with cardioembolic cerebral infarction, 24 patients showed proximal bright vessel sign (57.1%) and 25 showed susceptibility vessel sign (59.5%). There were 19 cases of proximal bright vessel sign and susceptibility vessel sign-clear, 12 cases of proximal bright vessel sign and susceptibility vessel sign-unclear, and 11 mismatched cases. Four out of 6 patients with proximal bright vessel sign-unclear and susceptibility vessel sign-clear showed distal middle cerebral artery occlusion, and 2 out of 5 patients with proximal bright vessel sign-clear and susceptibility vessel sign-unclear showed no occlusion on magnetic resonance angiography. Proximal bright vessel sign is almost compatible with susceptibility vessel sign in patients with cardioembolic cerebral infarction. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  20. Nuclear magnetic resonance studies of half-integer quadrupolar nuclei : sensitivity enhancements using double frequency sweeps

    NARCIS (Netherlands)

    Iuga, Dinu

    2003-01-01

    Exploiting adiabatic passages of the spin transitions, this thesis reports sensitivity enhancements of the MAS and MQMAS experiments on half-integer quadrupolar nuclei. The processes governing frequency sweeping are described. During such experiments the irradiation frequency sweeps through the

  1. Resonant coherent quantum tunneling of the magnetization of spin-systems: Spin-parity effects

    NARCIS (Netherlands)

    Garcia-Pablos, D; Garcia, N; de Raedt, H.A.

    1997-01-01

    We perform quantum dynamical calculations to study the reversal of the magnetization for systems of a few the presence of an external magnetic field at T=0 and with no dissipation. Collective quantum tunneling of the magnetization is demonstrated to occur only for some specific resonant values of

  2. RF MEMS Fractal Capacitors With High Self-Resonant Frequencies

    KAUST Repository

    Elshurafa, Amro M.

    2012-07-23

    This letter demonstrates RF microelectromechanical systems (MEMS) fractal capacitors possessing the highest reported self-resonant frequencies (SRFs) in PolyMUMPS to date. Explicitly, measurement results show SRFs beyond 20 GHz. Furthermore, quality factors higher than 4 throughout a band of 1-15 GHz and reaching as high as 28 were achieved. Additional benefits that are readily attainable from implementing fractal capacitors in MEMS are discussed, including suppressing residual stress warping, eliminating the need for etching holes, and reducing parasitics. The latter benefits were acquired without any fabrication intervention. © 2011 IEEE.

  3. Low frequency noise in resonant Josephson soliton oscillators

    DEFF Research Database (Denmark)

    Hansen, Jørn Bindslev; Holst, T.; Wellstood, Frederick C.

    1991-01-01

    The noise in the resonant soliton mode of long and narrow Josephson tunnel junctions (Josephson transmission lines or JTLs) have been measured in the frequency range from 0.1 Hz to 25 kHz by means of a DC SQUID. The measured white noise was found, to within a factor of two, to be equal...... to the Nyquist voltage noise in a resistance equal to the dynamic resistance RD of the current-voltage characteristic of the bias point. In contrast, measurements of the linewidth of the microwave radiation from the same JTL showed that the spectral density of the underlying noise voltage scaled as R D2/RS where...

  4. High frequency generation in the corona: Resonant cavities

    Science.gov (United States)

    Santamaria, I. C.; Van Doorsselaere, T.

    2018-03-01

    Aims: Null points are prominent magnetic field singularities in which the magnetic field strength strongly decreases in very small spatial scales. Around null points, predicted to be ubiquitous in the solar chromosphere and corona, the wave behavior changes considerably. Null points are also responsible for driving very energetic phenomena, and for contributing to chromospheric and coronal heating. In previous works we demonstrated that slow magneto-acoustic shock waves were generated in the chromosphere propagate through the null point, thereby producing a train of secondary shocks escaping along the field lines. A particular combination of the shock wave speeds generates waves at a frequency of 80 MHz. The present work aims to investigate this high frequency region around a coronal null point to give a plausible explanation to its generation at that particular frequency. Methods: We carried out a set of two-dimensional numerical simulations of wave propagation in the neighborhood of a null point located in the corona. We varied both the amplitude of the driver and the atmospheric properties to investigate the sensitivity of the high frequency waves to these parameters. Results: We demonstrate that the wave frequency is sensitive to the atmospheric parameters in the corona, but it is independent of the strength of the driver. Thus, the null point behaves as a resonant cavity generating waves at specific frequencies that depend on the background equilibrium model. Moreover, we conclude that the high frequency wave train generated at the null point is not necessarily a result of the interaction between the null point and a shock wave. This wave train can be also developed by the interaction between the null point and fast acoustic-like magneto-acoustic waves, that is, this interaction within the linear regime.

  5. Resonant behavior of a fractional oscillator with fluctuating frequency

    Science.gov (United States)

    Soika, Erkki; Mankin, Romi; Ainsaar, Ain

    2010-01-01

    The long-time behavior of the first moment for the output signal of a fractional oscillator with fluctuating frequency subjected to an external periodic force is considered. Colored fluctuations of the oscillator eigenfrequency are modeled as a dichotomous noise. The viscoelastic type friction kernel with memory is assumed as a power-law function of time. Using the Shapiro-Loginov formula, exact expressions for the response to an external periodic field and for the complex susceptibility are presented. On the basis of the exact formulas it is demonstrated that interplay of colored noise and memory can generate a variety of cooperation effects, such as multiresonances versus the driving frequency and the friction coefficient as well as stochastic resonance versus noise parameters. The necessary and sufficient conditions for the cooperation effects are also discussed. Particularly, two different critical memory exponents have been found, which mark dynamical transitions in the behavior of the system.

  6. Resonant behavior of a fractional oscillator with fluctuating frequency.

    Science.gov (United States)

    Soika, Erkki; Mankin, Romi; Ainsaar, Ain

    2010-01-01

    The long-time behavior of the first moment for the output signal of a fractional oscillator with fluctuating frequency subjected to an external periodic force is considered. Colored fluctuations of the oscillator eigenfrequency are modeled as a dichotomous noise. The viscoelastic type friction kernel with memory is assumed as a power-law function of time. Using the Shapiro-Loginov formula, exact expressions for the response to an external periodic field and for the complex susceptibility are presented. On the basis of the exact formulas it is demonstrated that interplay of colored noise and memory can generate a variety of cooperation effects, such as multiresonances versus the driving frequency and the friction coefficient as well as stochastic resonance versus noise parameters. The necessary and sufficient conditions for the cooperation effects are also discussed. Particularly, two different critical memory exponents have been found, which mark dynamical transitions in the behavior of the system.

  7. High-Frequency Electron Paramagnetic Resonance Spectroscopy of Nitroxide-Functionalized Nanodiamonds in Aqueous Solution.

    Science.gov (United States)

    Akiel, R D; Stepanov, V; Takahashi, S

    2017-06-01

    Nanodiamond (ND) is an attractive class of nanomaterial for fluorescent labeling, magnetic sensing of biological molecules, and targeted drug delivery. Many of those applications require tethering of target biological molecules on the ND surface. Even though many approaches have been developed to attach macromolecules to the ND surface, it remains challenging to characterize dynamics of tethered molecule. Here, we show high-frequency electron paramagnetic resonance (HF EPR) spectroscopy of nitroxide-functionalized NDs. Nitroxide radical is a commonly used spin label to investigate dynamics of biological molecules. In the investigation, we developed a sample holder to overcome water absorption of HF microwave. Then, we demonstrated HF EPR spectroscopy of nitroxide-functionalized NDs in aqueous solution and showed clear spectral distinction of ND and nitroxide EPR signals. Moreover, through EPR spectral analysis, we investigate dynamics of nitroxide radicals on the ND surface. The demonstration sheds light on the use of HF EPR spectroscopy to investigate biological molecule-functionalized nanoparticles.

  8. Spin-flip measurements in the proton inelastic scattering on 12C and giant resonance effects

    International Nuclear Information System (INIS)

    De Leo, R.; D'Erasmo, G.; Ferrero, F.; Pantaleo, A.; Pignanelli, M.

    1975-01-01

    Differential cross sections and spin-flip probabilities (SFP) for the inelastic scattering of protons, exciting the 2 + state at 4.43 MeV in 12 C, have been measured at several incident energies between 15.9 and 37.6 MeV. The changes in the shape of the SFP angular distributions are rather limited, while the absolute values show a pronounced increase, resonant like, in two energy regions centered at about 20 and 29 MeV. The second resonance reproduces very closely the energy dependence of the E2 giant quadrupole strength found in a previous experiment. The resonance at 20 MeV should correspond to a substructure of the E1 giant dipole resonance. (Auth.)

  9. An automated framework for NMR resonance assignment through simultaneous slice picking and spin system forming

    KAUST Repository

    Abbas, Ahmed

    2014-04-19

    Despite significant advances in automated nuclear magnetic resonance-based protein structure determination, the high numbers of false positives and false negatives among the peaks selected by fully automated methods remain a problem. These false positives and negatives impair the performance of resonance assignment methods. One of the main reasons for this problem is that the computational research community often considers peak picking and resonance assignment to be two separate problems, whereas spectroscopists use expert knowledge to pick peaks and assign their resonances at the same time. We propose a novel framework that simultaneously conducts slice picking and spin system forming, an essential step in resonance assignment. Our framework then employs a genetic algorithm, directed by both connectivity information and amino acid typing information from the spin systems, to assign the spin systems to residues. The inputs to our framework can be as few as two commonly used spectra, i.e., CBCA(CO)NH and HNCACB. Different from the existing peak picking and resonance assignment methods that treat peaks as the units, our method is based on \\'slices\\', which are one-dimensional vectors in three-dimensional spectra that correspond to certain (N, H) values. Experimental results on both benchmark simulated data sets and four real protein data sets demonstrate that our method significantly outperforms the state-of-the-art methods while using a less number of spectra than those methods. Our method is freely available at http://sfb.kaust.edu.sa/Pages/Software.aspx. © 2014 Springer Science+Business Media.

  10. Dissimilar trend of nonlinearity in ultrasound transducers and systems at resonance and non-resonance frequencies

    DEFF Research Database (Denmark)

    Ghasemi, Negareh; Zare, Firuz; Davari, Pooya

    2017-01-01

    Several factors can affect performance of an ultrasound system such as quality of excitation signal and ultrasound transducer behaviour. Nonlinearity of piezoelectric ultrasound transducers is a key determinant in designing a proper driving power supply. Although, the nonlinearity of piezoelectri...... receiver is a function of a voltage across the resistor in the RLC branches and is related to the resonance frequencies of the ultrasound transducer....

  11. Neutron resonance spin flippers: Static coils manufactured by electrical discharge machining

    Science.gov (United States)

    Martin, N.; Wagner, J. N.; Dogu, M.; Fuchs, C.; Kredler, L.; Böni, P.; Häußler, W.

    2014-07-01

    Radiofrequency spin flippers (RFSF) are key elements of Neutron Resonance Spin Echo (NRSE) spectrometers, which allow performing controlled manipulations of the beam polarization. We report on the design and test of a new type of RFSF which originality lies in the new manufacturing technique for the static coil. The largely automated procedure ensures reproducible construction as well as an excellent homogeneity of the neutron magnetic resonance condition over the coil volume. Two salient features of this concept are the large neutron window and the closure of the coil by a μ-metal yoke which prevents field leakage outside of the coil volume. These properties are essential for working with large beams and enable new applications with coils tilted with respect to the beam axis such as neutron Larmor diffraction or the study of dispersive excitations by inelastic NRSE.

  12. Neutron resonance spin flippers: Static coils manufactured by electrical discharge machining

    International Nuclear Information System (INIS)

    Martin, N.; Kredler, L.; Häußler, W.; Wagner, J. N.; Dogu, M.; Fuchs, C.; Böni, P.

    2014-01-01

    Radiofrequency spin flippers (RFSF) are key elements of Neutron Resonance Spin Echo (NRSE) spectrometers, which allow performing controlled manipulations of the beam polarization. We report on the design and test of a new type of RFSF which originality lies in the new manufacturing technique for the static coil. The largely automated procedure ensures reproducible construction as well as an excellent homogeneity of the neutron magnetic resonance condition over the coil volume. Two salient features of this concept are the large neutron window and the closure of the coil by a μ-metal yoke which prevents field leakage outside of the coil volume. These properties are essential for working with large beams and enable new applications with coils tilted with respect to the beam axis such as neutron Larmor diffraction or the study of dispersive excitations by inelastic NRSE

  13. Prospects for a Muon Spin Resonance Facility in the MuCool Test Area

    Energy Technology Data Exchange (ETDEWEB)

    Johnstone, John A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2017-04-12

    This paper investigates the feasibility of re-purposing the MuCool Test Area beamline and experimental hall to support a Muon Spin Resonance facility, which would make it the only such facility in the US. This report reviews the basic muon production concepts studied and operationally implemented at TRIUMF, PSI, and RAL and their application to the MTA facility. Two scenarios were determined feasible. One represents an initial minimal-shielding and capital-cost investment stage with a single secondary muon beamline that transports the primary beam to an existing high-intensity beam absorber located outside of the hall. Another, upgraded stage, involves an optimized production target pile and high-intensity absorber installed inside the experimental hall and potentially multiple secondary muon lines. In either scenario, with attention to target design, the MTA can host enabling and competitive Muon Spin Resonance experiments

  14. Resonant spin-wave modes in trilayered magnetic nanowires studied in the parallel and antiparallel ground state

    International Nuclear Information System (INIS)

    Gubbiotti, G.; Nguyen, H.T.; Hiramatsu, R.; Tacchi, S.; Cottam, M.G.; Ono, T.

    2015-01-01

    Brillouin light scattering has been utilized to study the field dependence of resonant spin-wave modes in layered NiFe(30 nm)/Cu(10 nm)/NiFe(15 nm)/Cu(10 nm)/NiFe(30 nm) nanowires of rectangular cross section, 150 nm wide and formed in arrays that are spaced laterally by 400 nm. The major and minor longitudinal hysteresis curves have been measured by the magneto-optical Kerr effect technique, with applied field parallel to the length of the nanowires. The light-scattering spectra were recorded as a function of the magnetic field strength, encompassing both the parallel and antiparallel alignments of the middle stripe with respect to the magnetization direction of the outermost ones. The field ranges for the antiparallel state are different from those for the parallel case, while the mode frequencies change abruptly at the parallel-to-antiparallel transition field (and vice versa). The modes detected in the antiparallel state are found to have only a weak dependence on the applied magnetic field, whether along the major or minor hysteresis curves, while in the parallel state the mode frequencies monotonically increase with the applied magnetic field. The experimental results have been successfully interpreted, across the whole range of the magnetic fields investigated, in terms of the mode localizations across the width and in the layered structure. This was accomplished by means of a microscopic (Hamiltonian-based) theory, which has been extended here to the case of non-parallel magnetic ground states. - Highlights: • We study the resonant spin waves in layered nanowires of rectangular cross section. • Both the parallel and antiparallel magnetization alignments have been explored. • Frequency of modes in the antiparallel state are independent on the magnetic field. • Experimental results we interpreted by means of an Hamiltonian-based theory

  15. Electron spin resonance of paramagnetic defects and related charge carrier traps in complex oxide scintillators

    Czech Academy of Sciences Publication Activity Database

    Laguta, Valentyn; Nikl, Martin

    2013-01-01

    Roč. 250, č. 2 (2013), s. 254-260 ISSN 0370-1972 R&D Projects: GA MŠk(CZ) LM2011029; GA ČR GAP204/12/0805; GA AV ČR IAA100100810 Grant - others:SAFMAT(XE) CZ.2.16/3.1.00/22132 Institutional support: RVO:68378271 Keywords : scintillators * point defects * electron spin resonance * polarons Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.605, year: 2013

  16. Magnetic resonance findings in amyotrophic lateral sclerosis using a spin echo magnetization transfer sequence: preliminary report

    Directory of Open Access Journals (Sweden)

    ROCHA ANTÔNIO JOSÉ DA

    1999-01-01

    Full Text Available We present the magnetic resonance (MR findings of five patients with amyotrophic lateral sclerosis (ALS using a spin-echo sequence with an additional magnetization transfer (MT pulse on T1-weighted images (T1 SE/MT. These findings were absent in the control group and consisted of hyperintensity of the corticospinal tract. Moreover we discuss the principles and the use of this fast but simple MR technique in the diagnosis of ALS

  17. The electron spin resonance study of heavily nitrogen doped 6H SiC crystals

    Czech Academy of Sciences Publication Activity Database

    Savchenko, Dariia

    2015-01-01

    Roč. 117, č. 4 (2015), "045708-1"-"045708-6" ISSN 0021-8979 R&D Projects: GA ČR GP13-06697P; GA MŠk(CZ) LM2011029 Grant - others:SAFMAT(XE) CZ.2.16/3.1.00/22132 Institutional support: RVO:68378271 Keywords : electron spin resonance * conduction electrons * 6H SiC * insulator-metal transition Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.101, year: 2015

  18. Electron spin resonance study of the demagnetization fields of the ferromagnetic and paramagnetic films

    Directory of Open Access Journals (Sweden)

    I.I. Gimazov, Yu.I. Talanov

    2015-12-01

    Full Text Available The results of the electron spin resonance study of the La1-xCaxMnO3 manganite and the diphenyl-picrylhydrazyl thin films for the magnetic field parallel and perpendicular to plane of the films are presented. The temperature dependence of the demagnetizing field is obtained. The parameters of the Curie-Weiss law are estimated for the paramagnetic thin film.

  19. Insights on the Structural Details of Endonuclease EcoRI-DNA Complexes by Electron Spin Resonance

    Science.gov (United States)

    Sarver, Jessica

    2009-03-01

    Pulsed electron spin resonance (ESR) was used to probe the binding specificity of EcoRI, a restriction endonuclease. Using site-directed spin labeling, a nitroxide side chain was incorporated into the protein, enabling the use of ESR to study structural details of EcoRI. Distance measurements were performed on EcoRI mutants when bound to varying sequences of DNA using the Double Electron-Electron Resonance experiment. These distances demonstrated that the average structure in the arm regions of EcoRI, thought to play a major role in binding specificity, is the same when the protein binds to different sequences of DNA. Also, it was determined that the arms exhibit higher flexibility when bound to sequences other than the specific sequence due to the larger distance distributions acquired from these spin labeled complexes. Molecular dynamics (MD) simulations were performed on the spin-label-modified specific EcoRI-DNA crystal structure to model the average nitroxide orientation. The distance distributions from MD were found to be narrower than experiment, indicating the need for a more rigorous sampling of the nitroxide conformers in silico.

  20. ν =2 /3 fractional quantum Hall state in an AlAs quantum well probed by electron spin resonance

    Science.gov (United States)

    Shchepetilnikov, A. V.; Frolov, D. D.; Nefyodov, Yu. A.; Kukushkin, I. V.; Tiemann, L.; Reichl, C.; Dietsche, W.; Wegscheider, W.

    2017-10-01

    The electron spin resonance (ESR) of two-dimensional electrons confined in a high-quality, 16-nm AlAs quantum well was investigated near the filling factor ν =2 /3 of the fractional quantum Hall effect (FQHE). The spin resonance was robust in the vicinity of the fractional filling ν =2 /3 , indicating that the ν =2 /3 state is at least partially spin polarized. The formation of the 2 /3 FQHE state did not result in any modifications of the ESR linewidth and, hence, of the electron spin relaxation rate. Yet the nuclear spin-lattice relaxation rate extracted from the time decay of the ESR Overhauser shift demonstrated a strong nonmonotonic dependence on the electron filling factor with a minimum near ν =2 /3 . This observation suggests the enhancement of the energy gap in the spin excitation spectrum of two-dimensional electrons at the ν =2 /3 state.

  1. YBa{sub 2}Cu{sub 3}O{sub 7} microwave resonators for strong collective coupling with spin ensembles

    Energy Technology Data Exchange (ETDEWEB)

    Ghirri, A., E-mail: alberto.ghirri@nano.cnr.it [Istituto Nanoscienze - CNR, Centro S3, via Campi 213/a, 41125 Modena (Italy); Bonizzoni, C.; Affronte, M. [Dipartimento Fisica, Informatica e Matematica, Università di Modena e Reggio Emilia and Istituto Nanoscienze - CNR, Centro S3, via Campi 213/a, 41125 Modena (Italy); Gerace, D.; Sanna, S. [Dipartimento di Fisica, Università di Pavia, via Bassi 6, 27100 Pavia (Italy); Cassinese, A. [CNR-SPIN and Dipartimento di Fisica, Università di Napoli Federico II, 80138 Napoli (Italy)

    2015-05-04

    Coplanar microwave resonators made of 330 nm-thick superconducting YBa{sub 2}Cu{sub 3}O{sub 7} have been realized and characterized in a wide temperature (T, 2–100 K) and magnetic field (B, 0–7 T) range. The quality factor (Q{sub L}) exceeds 10{sup 4} below 55 K and it slightly decreases for increasing fields, remaining 90% of Q{sub L}(B=0) for B = 7 T and T = 2 K. These features allow the coherent coupling of resonant photons with a spin ensemble at finite temperature and magnetic field. To demonstrate this, collective strong coupling was achieved by using di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium organic radical placed at the magnetic antinode of the fundamental mode: the in-plane magnetic field is used to tune the spin frequency gap splitting across the single-mode cavity resonance at 7.75 GHz, where clear anticrossings are observed with a splitting as large as ∼82 MHz at T = 2 K. The spin-cavity collective coupling rate is shown to scale as the square root of the number of active spins in the ensemble.

  2. Phase-resolved detection of the spin Hall angle by optical ferromagnetic resonance in perpendicularly magnetized thin films

    Science.gov (United States)

    Capua, Amir; Wang, Tianyu; Yang, See-Hun; Rettner, Charles; Phung, Timothy; Parkin, Stuart S. P.

    2017-02-01

    The conversion of charge current to spin current by the spin Hall effect is of considerable current interest from both fundamental and technological perspectives. Measurement of the spin Hall angle, especially for atomically thin systems with large magnetic anisotropies, is not straightforward. Here we demonstrate a hybrid phase-resolved optical-electrical ferromagnetic resonance method that we show can robustly determine the spin Hall angle in heavy-metal/ferromagnet bilayer systems with large perpendicular magnetic anisotropy. We present an analytical model of the ferromagnetic resonance spectrum in the presence of the spin Hall effect, in which the spin Hall angle can be directly determined from the changes in the amplitude response as a function of the spin current that is generated from a dc charge current passing through the heavy-metal layer. Increased sensitivity to the spin current is achieved by operation under conditions for which the magnetic potential is shallowest at the "Smit point." Study of the phase response reveals that the spin Hall angle can be reliably extracted from a simplified measurement that does not require scanning over time or magnetic field but rather only on the dc current. The method is applied to the Pt-Co/Ni/Co system whose spin Hall angle was to date characterized only indirectly and that is especially relevant for spin-orbit torque devices.

  3. Coherent Zeeman resonance from electron spin coherence in a mixed-type GaAs/AlAs quantum well.

    Science.gov (United States)

    O'Leary, Shannon; Wang, Hailin; Prineas, John P

    2007-03-01

    Coherent Zeeman resonance from electron spin coherence is demonstrated in a Lambda-type three-level system, coupling electron spin states via trions. The optical control of electron density that is characteristic of a mixed-type quantum-well facilitates the study of trion formation as well as the effects of many-body interactions on the manifestation of electron spin coherence in the nonlinear optical response.

  4. Electron spin resonance identification di-carbon-related centers in irradiated silicon

    Science.gov (United States)

    Hayashi, S.; Saito, H.; Itoh, K. M.; Vlasenko, M. P.; Vlasenko, L. S.

    2018-04-01

    A previously unreported electron spin resonance (ESR) spectrum was found in γ-ray irradiated silicon by the detection of the change in microwave photoconductivity arising from spin-dependent recombination (SDR). In the specially prepared silicon crystals doped by 13C isotope, a well resolved hyperfine structure of SDR-ESR lines due to the interaction between electrons and two equivalent carbon atoms having nuclear spin I = 1/2 was observed. The Si-KU4 spectrum is described by spin Hamiltonian for spin S = 1 and of g and D tensors of orthorhombic symmetry with principal values g1 = 2.008, g2 = 2.002, and g3 =2.007; and D1 = ± 103 MHz, D2 = ∓170 MHz, and D3 = ± 67 MHz where axes 1, 2, and 3 are parallel to the [1 1 ¯ 0 ], [110], and [001] crystal axes, respectively. The hyperfine splitting arising from 13C nuclei is about 0.35 mT. A possible microstructure of the detect leading to the Si-KU4 spectrum is discussed.

  5. Advances and applications of dynamic-angle spinning nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Baltisberger, Jay Harvey [Univ. of California, Berkeley, CA (United States)

    1993-06-01

    This dissertation describes nuclear magnetic resonance experiments and theory which have been developed to study quadrupolar nuclei (those nuclei with spin greater than one-half) in the solid state. Primarily, the technique of dynamic-angle spinning (DAS) is extensively reviewed and expanded upon in this thesis. Specifically, the improvement in both the resolution (two-dimensional pure-absorptive phase methods and DAS angle choice) and sensitivity (pulse-sequence development), along with effective spinning speed enhancement (again through choice of DAS conditions or alternative multiple pulse schemes) of dynamic-angle spinning experiment was realized with both theory and experimental examples. The application of DAS to new types of nuclei (specifically the {sup 87}Rb and {sup 85}Rb nuclear spins) and materials (specifically amorphous solids) has also greatly expanded the possibilities of the use of DAS to study a larger range of materials. This dissertation is meant to demonstrate both recent advances and applications of the DAS technique, and by no means represents a comprehensive study of any particular chemical problem.

  6. Advances and applications of dynamic-angle spinning nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Baltisberger, J.H.

    1993-06-01

    This dissertation describes nuclear magnetic resonance experiments and theory which have been developed to study quadrupolar nuclei (those nuclei with spin greater than one-half) in the solid state. Primarily, the technique of dynamic-angle spinning (DAS) is extensively reviewed and expanded upon in this thesis. Specifically, the improvement in both the resolution (two-dimensional pure-absorptive phase methods and DAS angle choice) and sensitivity (pulse-sequence development), along with effective spinning speed enhancement (again through choice of DAS conditions or alternative multiple pulse schemes) of dynamic-angle spinning experiment was realized with both theory and experimental examples. The application of DAS to new types of nuclei (specifically the 87 Rb and 85 Rb nuclear spins) and materials (specifically amorphous solids) has also greatly expanded the possibilities of the use of DAS to study a larger range of materials. This dissertation is meant to demonstrate both recent advances and applications of the DAS technique, and by no means represents a comprehensive study of any particular chemical problem

  7. Hyperfine contributions to spin-exchange frequency shifts in the hydrogen maser

    NARCIS (Netherlands)

    Verhaar, B.J.; Koelman, J.M.V.A.; Stoof, H.T.C.; Luiten, O.J.; Crampton, S.B.

    1987-01-01

    We have rigorously included hyperfine interactions during electron-spin-exchange collisions between ground state hydrogen atoms. We predict additional frequency shifts which are not compensated for by the usual methods of tuning maser cavities. These shifts are large compared to the potential

  8. Characteristics of spondylotic myelopathy on 3D driven-equilibrium fast spin echo and 2D fast spin echo magnetic resonance imaging: a retrospective cross-sectional study.

    Science.gov (United States)

    Abdulhadi, Mike A; Perno, Joseph R; Melhem, Elias R; Nucifora, Paolo G P

    2014-01-01

    In patients with spinal stenosis, magnetic resonance imaging of the cervical spine can be improved by using 3D driven-equilibrium fast spin echo sequences to provide a high-resolution assessment of osseous and ligamentous structures. However, it is not yet clear whether 3D driven-equilibrium fast spin echo sequences adequately evaluate the spinal cord itself. As a result, they are generally supplemented by additional 2D fast spin echo sequences, adding time to the examination and potential discomfort to the patient. Here we investigate the hypothesis that in patients with spinal stenosis and spondylotic myelopathy, 3D driven-equilibrium fast spin echo sequences can characterize cord lesions equally well as 2D fast spin echo sequences. We performed a retrospective analysis of 30 adult patients with spondylotic myelopathy who had been examined with both 3D driven-equilibrium fast spin echo sequences and 2D fast spin echo sequences at the same scanning session. The two sequences were inspected separately for each patient, and visible cord lesions were manually traced. We found no significant differences between 3D driven-equilibrium fast spin echo and 2D fast spin echo sequences in the mean number, mean area, or mean transverse dimensions of spondylotic cord lesions. Nevertheless, the mean contrast-to-noise ratio of cord lesions was decreased on 3D driven-equilibrium fast spin echo sequences compared to 2D fast spin echo sequences. These findings suggest that 3D driven-equilibrium fast spin echo sequences do not need supplemental 2D fast spin echo sequences for the diagnosis of spondylotic myelopathy, but they may be less well suited for quantitative signal measurements in the spinal cord.

  9. Electron spin resonance and nuclear magnetic resonance of sodium macrostructures in strongly irradiated NaCl-K crystals: Manifestation of quasi-one-dimensional behavior of electrons

    NARCIS (Netherlands)

    Cherkasov, FG; Mustafin, RG; L'vov, SG; Denisenko, GA; den Hartog, HW; Vainshtein, D. I.

    1998-01-01

    Data from an investigation of electron spin resonance and nuclear magnetic resonance of NaCl-K (similar to 1 mole%) crystals strongly irradiated with electrons imply the observation of a metal-insulator transition with decreasing temperature and the manifestation of quasi-one-dimensional electron

  10. Diffusion studies on permeable nitroxyl spin probes through bilayer lipid membranes: A low frequency ESR study

    Energy Technology Data Exchange (ETDEWEB)

    Meenakumari, V.; Benial, A. Milton Franklin, E-mail: miltonfranklin@yahoo.com [Department of Physics, NMSSVN College, Nagamalai, Madurai-625019, Tamilnadu (India); Utsumi, Hideo; Ichikawa, Kazuhiro; Yamada, Ken-ichi [Department of Bio-functional Science, Kyushu University, Fukuoka (Japan); Hyodo, Fuminori [Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka (Japan); Jawahar, A. [Department of Chemistry, NMSSVN College, Nagamalai, Madurai-625019, Tamilnadu (India)

    2015-06-24

    Electron spin resonance (ESR) studies were carried out for permeable 2mM {sup 14}N-labeled deutrated 3 Methoxy carbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl (MC-PROXYL) in pure water and 1mM, 2mM, 3mM, 4mM concentration of 14N-labeled deutrated MC-PROXYL in 400mM concentration of liposomal solution by using a 300 MHz ESR spectrometer. The ESR parameters such as linewidth, hyperfine coupling constant, g-factor, partition parameter and permeability were reported for these samples. The line broadening was observed for the nitroxyl spin probe in the liposomal solution. The line broadening indicates that the high viscous nature of the liposomal solution. The partition parameter and permeability values indicate the maximum diffusion of nitroxyl spin probes in the bilayer lipid membranes at 2 mM concentration of nitroxyl radical. This study illustrates that ESR can be used to differentiate between the intra and extra- membrane water by loading the liposome vesicles with a lipid-permeable nitroxyl spin probe. From the ESR results, the spin probe concentration was optimized as 2mM in liposomal solution for ESR phantom studies/imaging, invivo and invitro experiments.

  11. A High-Spin Rate Measurement Method for Projectiles Using a Magnetoresistive Sensor Based on Time-Frequency Domain Analysis.

    Science.gov (United States)

    Shang, Jianyu; Deng, Zhihong; Fu, Mengyin; Wang, Shunting

    2016-06-16

    Traditional artillery guidance can significantly improve the attack accuracy and overall combat efficiency of projectiles, which makes it more adaptable to the information warfare of the future. Obviously, the accurate measurement of artillery spin rate, which has long been regarded as a daunting task, is the basis of precise guidance and control. Magnetoresistive (MR) sensors can be applied to spin rate measurement, especially in the high-spin and high-g projectile launch environment. In this paper, based on the theory of a MR sensor measuring spin rate, the mathematical relationship model between the frequency of MR sensor output and projectile spin rate was established through a fundamental derivation. By analyzing the characteristics of MR sensor output whose frequency varies with time, this paper proposed the Chirp z-Transform (CZT) time-frequency (TF) domain analysis method based on the rolling window of a Blackman window function (BCZT) which can accurately extract the projectile spin rate. To put it into practice, BCZT was applied to measure the spin rate of 155 mm artillery projectile. After extracting the spin rate, the impact that launch rotational angular velocity and aspect angle have on the extraction accuracy of the spin rate was analyzed. Simulation results show that the BCZT TF domain analysis method can effectively and accurately measure the projectile spin rate, especially in a high-spin and high-g projectile launch environment.

  12. Topology and criticality in the resonating Affleck-Kennedy-Lieb-Tasaki loop spin liquid states

    Science.gov (United States)

    Li, Wei; Yang, Shuo; Cheng, Meng; Liu, Zheng-Xin; Tu, Hong-Hao

    2014-05-01

    We exploit a natural projected entangled-pair state (PEPS) representation for the resonating Affleck-Kennedy-Lieb-Tasaki loop (RAL) state. By taking advantage of PEPS-based analytical and numerical methods, we characterize the RAL states on various two-dimensional lattices. On square and honeycomb lattices, these states are critical since the dimer-dimer correlations decay as a power law. On the kagome lattice, the RAL state has exponentially decaying correlation functions, supporting the scenario of a gapped spin liquid. We provide further evidence that the RAL state on the kagome lattice is a Z2 spin liquid, by identifying the four topological sectors and computing the topological entropy. Furthermore, we construct a one-parameter family of PEPS states interpolating between the RAL state and a short-range resonating valence bond state and find a critical point, consistent with the fact that the two states belong to two different phases. We also perform a variational study of the spin-1 kagome Heisenberg model using this one-parameter PEPS.

  13. Frequency-dependent dynamic magnetic properties of the Ising bilayer system consisting of spin-3/2 and spin-5/2 spins

    Science.gov (United States)

    Keskin, Mustafa; Ertaş, Mehmet

    2018-04-01

    Dynamic magnetic properties of the Ising bilayer system consisting of the mixed (3/2, 5/2) Ising spins with a crystal-field interaction in an oscillating field on a two-layer square lattice is studied by the use of dynamic mean-field theory based on the Glauber-type stochastic. Dynamic phase transition temperatures are obtained and dynamic phase diagrams are presented in three different planes. The frequency dependence of dynamic hysteresis loops is also investigated in detail. We compare the results with some available theoretical and experimental works and observe a quantitatively good agreement with some theoretical and experimental results.

  14. Spin Resonance in the New-Structure-Type Iron-Based Superconductor CaKFe4As4

    Science.gov (United States)

    Iida, Kazuki; Ishikado, Motoyuki; Nagai, Yuki; Yoshida, Hiroyuki; Christianson, Andrew D.; Murai, Naoki; Kawashima, Kenji; Yoshida, Yoshiyuki; Eisaki, Hiroshi; Iyo, Akira

    2017-09-01

    The dynamical spin susceptibility in the new-structure-type iron-based superconductor CaKFe4As4 was investigated by using a combination of inelastic neutron scattering (INS) measurements and random phase approximation (RPA) calculations. Powder INS measurements show that the spin resonance at Qres = 1.17(1) Å-1, corresponding to the (π ,π ) nesting wave vector in tetragonal notation, evolves below Tc. The characteristic energy of the spin resonance Eres = 12.5 meV is smaller than twice the size of the superconducting gap (2Δ). The broad energy feature of the dynamical susceptibility of the spin resonance can be explained by the RPA calculations, in which the different superconducting gaps on different Fermi surfaces are taken into account. Our INS and PRA studies demonstrate that the superconducting pairing nature in CaKFe4As4 is the s± symmetry.

  15. Electron Spin Resonance Spectroscopy for Studying the Generation and Scavenging of Reactive Oxygen Species by Nanomaterials

    Science.gov (United States)

    Yin, Jun-Jie; Zhao, Baozhong; Xia, Qingsu; Fu, Peter P.

    2013-09-01

    One fundamental mechanism widely described for nanotoxicity involves oxidative damage due to generation of free radicals and other reactive oxygen species. Indeed, the ability of nanoscale materials to facilitate the transfer of electrons, and thereby promote oxidative damage or in some instances provide antioxidant protection, may be a fundamental property of these materials. Any assessment of a nanoscale material's safety must therefore consider the potential for toxicity arising from oxidative damage. Therefore, rapid and predictive methods are needed to assess oxidative damage elicited by nanoscale materials. The use of electron spin resonance (ESR) to study free radical related bioactivity of nanomaterials has several advantages for free radical determination and identification. Specifically it can directly assess antioxidant quenching or prooxidant generation of relevant free radicals and reactive oxygen species. In this chapter, we have reported some nonclassical behaviors of the electron spin relaxation properties of unpaired electrons in different fullerenes and the investigation of anti/prooxidant activity by various types of nanomaterials using ESR. In addition, we have reviewed the mechanisms of free radical formation photosensitized by different nanomaterials. This chapter also included the use of spin labels, spin traps and ESR oximetry to systematically examine the enzymatic mimetic activities of nanomaterials.

  16. Demonstration of Atomic Frequency Comb Memory for Light with Spin-Wave Storage

    Science.gov (United States)

    Afzelius, Mikael; Usmani, Imam; Amari, Atia; Lauritzen, Björn; Walther, Andreas; Simon, Christoph; Sangouard, Nicolas; Minář, Jiří; de Riedmatten, Hugues; Gisin, Nicolas; Kröll, Stefan

    2010-01-01

    We present a light-storage experiment in a praseodymium-doped crystal where the light is mapped onto an inhomogeneously broadened optical transition shaped into an atomic frequency comb. After absorption of the light, the optical excitation is converted into a spin-wave excitation by a control pulse. A second control pulse reads the memory (on-demand) by reconverting the spin-wave excitation to an optical one, where the comb structure causes a photon-echo-type rephasing of the dipole moments and directional retrieval of the light. This combination of photon-echo and spin-wave storage allows us to store submicrosecond (450 ns) pulses for up to 20μs. The scheme has a high potential for storing multiple temporal modes in the single-photon regime, which is an important resource for future long-distance quantum communication based on quantum repeaters.

  17. Spin-orbit driven ferromagnetic resonance: a nanoscale magnetic characterisation technique

    Czech Academy of Sciences Publication Activity Database

    Fang, D.; Kurebayashi, H.; Wunderlich, Joerg; Výborný, Karel; Zarbo, Liviu; Campion, R. P.; Casiraghi, A.; Gallagher, B. L.; Jungwirth, Tomáš; Ferguson, A.J.

    2011-01-01

    Roč. 6, č. 7 (2011), s. 413-417 ISSN 1748-3387 R&D Projects: GA AV ČR KAN400100652; GA MŠk LC510; GA AV ČR KJB100100802; GA MŠk(CZ) 7E08087 EU Projects: European Commission(XE) 214499 - NAMASTE; European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : ferromagnetic resonance * spin-orbit coupling * nanomagnets Subject RIV: BM - Solid Matter Physics ; Magnet ism Impact factor: 27.270, year: 2011

  18. Correlated spin currents generated by resonant-crossed Andreev reflections in topological superconductors

    Science.gov (United States)

    He, James J.; Wu, Jiansheng; Choy, Ting-Pong; Liu, Xiong-Jun; Tanaka, Y.; Law, K. T.

    2014-01-01

    Topological superconductors, which support Majorana fermion excitations, have been the subject of intense studies due to their novel transport properties and their potential applications in fault-tolerant quantum computations. Here we propose a new type of topological superconductors that can be used as a novel source of correlated spin currents. We show that inducing superconductivity on a AIII class topological insulator wire, which respects a chiral symmetry and supports protected fermionic end states, will result in a topological superconductor. This topological superconductor supports two topological phases with one or two Majorana fermion end states, respectively. In the phase with two Majorana fermions, the superconductor can split Cooper pairs efficiently into electrons in two spatially separated leads due to Majorana-induced resonant-crossed Andreev reflections. The resulting currents in the leads are correlated and spin-polarized. Importantly, the proposed topological superconductors can be realized using quantum anomalous Hall insulators in proximity to superconductors. PMID:24492649

  19. Use of resonance ionization spectroscopy to detect DNA bands on ultrathin spin-coated gels.

    Science.gov (United States)

    Doktycz, M J; Gibson, W A; Arlinghaus, H F; Allen, R C; Jacobson, K B

    1993-01-01

    Development of alternative electrophoresis procedures are necessary for large volume sequencing and mapping studies. The use of stable isotopes as DNA labels and ultrathin gels promises to greatly increase the rate of sequencing. Spin coating is presented as an alternative method for producing ultrathin polyacrylamide gels. The technique has the potential of producing gels of micron to submicron thicknesses by varying the viscosity of the acrylamide solution and the spinning speed. Thirty micron thick 6% (weight %) gels were produced in this manner. Tin-labeled DNA oligomers were electrophoresed and detected using sputter-initiated resonance ionization spectroscopy (SIRIS). The usefulness of SIRIS and laser atomization RIS (LARIS) to sample the surface and deeper layers of 240 microns thick gels was investigated. With LARIS, whole cross-sections of the gel can be atomized, possibly allowing complete sampling of labels.

  20. Nuclear spin relaxation/resonance of {sup 8}Li in Al

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Salman, Z. [Clarendon Laboratory, Department of Physics, Oxford University, Parks Road, Oxford OX1 3PU (United Kingdom); ISIS Facility, Rutherford-Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Chow, K.H.; Fan, I. [Department of Physics, University of Alberta, Edmonton, AB, T6G 2G7 (Canada); Hossain, M.D.; Keeler, T.A. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Kiefl, R.F., E-mail: kiefl@triumf.c [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Canadian Institute for Advanced Research (Canada); Levy, C.D.P. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Mansour, A.I. [Department of Physics, University of Alberta, Edmonton, AB, T6G 2G7 (Canada); Morris, G.D.; Pearson, M.R. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Parolin, T.J. [Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z3 (Canada); Saadaoui, H.; Smadella, M.; Song, Q. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); MacFarlane, W.A. [Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z3 (Canada)

    2009-04-15

    A low energy beam of spin polarized {sup 8}Li has been used to study the behaviour of isolated {sup 8}Li implanted into a 150 nm thick film of Al on an MgO substrate. The spin relaxation rate 1/T{sub 1} and beta-NMR lineshape were measured as a function of temperature in a large magnetic field of 4.1 T. The resonances from different sites are unresolved due to the large nuclear dipolar interaction with the host {sup 27}Al magnetic dipole moments. Nevertheless the temperature variation of the site averaged 1/T{sub 1} and Knight shift show evidence for a transition between the octahedral O and substitutional S sites at about 150 K, as observed in other fcc metals.

  1. Electron spin resonance of nitrogen-vacancy centers in optically trapped nanodiamonds

    Science.gov (United States)

    Horowitz, Viva R.; Alemán, Benjamín J.; Christle, David J.; Cleland, Andrew N.; Awschalom, David D.

    2012-01-01

    Using an optical tweezers apparatus, we demonstrate three-dimensional control of nanodiamonds in solution with simultaneous readout of ground-state electron-spin resonance (ESR) transitions in an ensemble of diamond nitrogen-vacancy color centers. Despite the motion and random orientation of nitrogen-vacancy centers suspended in the optical trap, we observe distinct peaks in the measured ESR spectra qualitatively similar to the same measurement in bulk. Accounting for the random dynamics, we model the ESR spectra observed in an externally applied magnetic field to enable dc magnetometry in solution. We estimate the dc magnetic field sensitivity based on variations in ESR line shapes to be approximately . This technique may provide a pathway for spin-based magnetic, electric, and thermal sensing in fluidic environments and biophysical systems inaccessible to existing scanning probe techniques. PMID:22869706

  2. Observation of the Distribution of Molecular Spin States by Resonant Quantum Tunneling of the Magnetization

    Science.gov (United States)

    Wernsdorfer, W.; Ohm, T.; Sangregorio, C.; Sessoli, R.; Mailly, D.; Paulsen, C.

    1999-05-01

    Below 360 mK, Fe8 magnetic molecular clusters are in the pure quantum relaxation regime and we show that the predicted ``square-root time'' relaxation is obeyed, allowing us to develop a new method for watching the evolution of the distribution of molecular spin states in the sample. We measure as a function of applied field H the statistical distribution P\\(ξH\\) of magnetic energy bias ξH acting on the molecules. Tunneling initially causes rapid transitions of molecules, thereby ``digging a hole'' in P\\(ξH\\) (around the resonant condition ξH = 0). For small initial magnetization values, the hole width shows an intrinsic broadening which may be due to nuclear spins.

  3. Effect of ionising radiation on potassium pentacyanonitrosyl ruthenate(II): an electron spin resonance study

    Energy Technology Data Exchange (ETDEWEB)

    Vugman, Ney V.; Pinhal, Nelson M.; Amorim, Helio S. de [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Fisica. Dept. de Fisica dos Solidos. E-mail: ney@if.ufrj.br; Santos, Cristina M.P. dos; Faria, Roberto B. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Quimica. Dept. de Quimica Inorganica

    2000-06-01

    Amorphous potassium pentacyanonitrosyl ruthenate (II) was synthesized and characterized by UV, IR, X-ray diffraction and thermogravimetric analysis. Electron Spin Resonance spectroscopy reveals the presence of paramagnetic ruthenate (i) complexes and NO{sub 2} radicals in the X-irradiated diamagnetic salt. Spin-Hamiltonian parameters of the [Ru (CN){sub 5} N O]{sup 3-} complex (g=2.0064, A ({sup 14} N) = 60.7 MHz, g = 1.999, A ({sup 14} N) = 77.3 MHz) support an electron capture in a {pi}{sup *} molecular orbital of the nitrosyl group mixed with d{sub xz} and d{sub yz} ruthenium orbitals as recently predicted by theoretical calculations. Silver ions, present as impurities, are reduced to Ag(o) by X-irradiation and coordinate to four magnetically equivalent nitrogens in a distorted site, giving to a well resolved anisotropic ESR powder spectrum. (author)

  4. Steady state obliquity of a rigid body in the spin-orbit resonant problem: application to Mercury

    Science.gov (United States)

    Lhotka, Christoph

    2017-12-01

    We investigate the stable Cassini state 1 in the p : q spin-orbit resonant problem. Our study includes the effect of the gravitational potential up to degree and order 4 and p : q spin-orbit resonances with p,q≤ 8 and p≥ q. We derive new formulae that link the gravitational field coefficients with its secular orbital elements and its rotational parameters. The formulae can be used to predict the orientation of the spin axis and necessary angular momentum at exact resonance. We also develop a simple pendulum model to approximate the dynamics close to resonance and make use of it to predict the libration periods and widths of the oscillatory regime of motions in phase space. Our analytical results are based on averaging theory that we also confirm by means of numerical simulations of the exact dynamical equations. Our results are applied to a possible rotational history of Mercury.

  5. Spin Resonance Clock Transition of the Endohedral Fullerene ^{15}N@C_{60}.

    Science.gov (United States)

    Harding, R T; Zhou, S; Zhou, J; Lindvall, T; Myers, W K; Ardavan, A; Briggs, G A D; Porfyrakis, K; Laird, E A

    2017-10-06

    The endohedral fullerene ^{15}N@C_{60} has narrow electron paramagnetic resonance lines which have been proposed as the basis for a condensed-matter portable atomic clock. We measure the low-frequency spectrum of this molecule, identifying and characterizing a clock transition at which the frequency becomes insensitive to magnetic field. We infer a linewidth at the clock field of 100 kHz. Using experimental data, we are able to place a bound on the clock's projected frequency stability. We discuss ways to improve the frequency stability to be competitive with existing miniature clocks.

  6. (1) Majorana fermions in pinned vortices; (2) Manipulating and probing Majorana fermions using superconducting circuits; and (3) Controlling a nanowire spin-orbit qubit via electric-dipole spin resonance

    Science.gov (United States)

    Nori, Franco

    2014-03-01

    We study a heterostructure which consists of a topological insulator and a superconductor with a hole. This system supports a robust Majorana fermion state bound to the vortex core. We study the possibility of using scanning tunneling spectroscopy (i) to detect the Majorana fermion in this setup and (ii) to study excited states bound to the vortex core. The Majorana fermion manifests itself as an H-dependent zero-bias anomaly of the tunneling conductance. The excited states spectrum differs from the spectrum of a typical Abrikosov vortex, providing additional indirect confirmation of the Majorana state observation. We also study how to manipulate and probe Majorana fermions using super-conducting circuits. In we consider a semiconductor nanowire quantum dot with strong spin-orbit coupling (SOC), which can be used to achieve a spin-orbit qubit. In contrast to a spin qubit, the spin-orbit qubit can respond to an external ac electric field, i.e., electric-dipole spin resonance. We develop a theory that can apply in the strong SOC regime. We find that there is an optimal SOC strength ηopt = √ 2/2, where the Rabi frequency induced by the ac electric field becomes maximal. Also, we show that both the level spacing and the Rabi frequency of the spin-orbit qubit have periodic responses to the direction of the external static magnetic field. These responses can be used to determine the SOC in the nanowire. FN is partly supported by the RIKEN CEMS, iTHES Project, MURI Center for Dynamic Magneto-Optics, JSPS-RFBR Contract No. 12-02-92100, Grant-in-Aid for Scientific Research (S), MEXT Kakenhi on Quantum Cybernetics, and the JSPS via its FIRST program.

  7. Spin 3/2 and 5/2 nucleon resonances in kaon electroproduction

    Energy Technology Data Exchange (ETDEWEB)

    Mart, T. [Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia)

    2016-04-19

    We have analyzed the available kaon electroproduction data by using the field theoretical approach involving spin 3/2 and 5/2 nucleon resonances. To this end we extend our previous isobar model for photoproduction to the finite Q{sup 2} region by making use of different electromagnetic form factors. The result indicates that kaon electroproduction data can be nicely described by the photoproduction isobar model, provided that the inserted electromagnetic form factors in all electromagnetic vertices are constructed from a combination of dipole and exponential form factors is included in all electromagnetic vertices.

  8. Electron spin resonance (ESR) studies on irradiated cocoa beans and niger seeds

    International Nuclear Information System (INIS)

    Mangaonkar, S.R.; Natarajan, V.; Sastry, M.D.; Desai, S.R.P.; Kulkarni, P.R.

    1997-01-01

    Electron spin resonance (ESR) spectra of irradiated (10kGy) and unirradiated cocoa beans and niger seeds have been compared. Unirradiated cocoa beans failed to give any ESR signal, whereas after irradiation (10kGy) an ESR signal at g = 2.0042 was observed. However, ESR signals are given by both irradiated and unirradiated niger seeds. The intensity of signal was found to be dose-dependent up to 10kGy for both seeds. The signals were stable up to 180 days in both cases. The results indicate the possibility of using ESR for distinguishing between irradiated and unirradiated cocoa beans but not for niger seeds

  9. Theory of Electric-Field Effects on Electron-Spin-Resonance Hyperfine Couplings

    International Nuclear Information System (INIS)

    Karna, S.P.

    1997-01-01

    A quantum mechanical theory of the effects of a uniform electric field on electron-spin-resonance hyperfine couplings is presented. The electric-field effects are described in terms of perturbation coefficients which can be used to probe the local symmetry as well as the strength of the electric field at paramagnetic sites in a solid. Results are presented for the first-order perturbation coefficients describing the Bloembergen effect (linear electric-field effect on hyperfine coupling tensor) for the O atom and the OH radical. copyright 1997 The American Physical Society

  10. Laser-excited Fluorescence And Electron-spin Resonance Of Er3+ In Polycrystalline Alcl3

    OpenAIRE

    Ceotto G.; Pires M.A.; Sanjurjo J.A.; Rettori C.; Barberis G.E.

    1990-01-01

    The green fluorescence transitions among the levels corresponding to the 4S3/2 and 4I15/2 configurations of Er3+ diluted in AlCl3 have been measured using laser excitation. The data allow us to determine the crystalline-field splittings of these levels and, in turn, the spin-Hamiltonian parameters. The electron-paramagnetic-resonance spectrum observed at low temperatures is in good agreement with that expected from these parameters. © 1990 The American Physical Society.

  11. Electron spin resonance signal from a tetra-interstitial defect in silicon

    CERN Document Server

    Mchedlidze, T

    2003-01-01

    The Si-B3 electron spin resonance (ESR) signal from agglomerates of self-interstitials was detected for the first time in hydrogen-doped float-zone-grown silicon samples subjected to annealing after electron irradiation. Previously this signal had been detected only in neutron- or proton-irradiated silicon samples. The absence of obscuring ESR peaks for the investigated samples at applied measurement conditions allowed an investigation of the hyperfine structure of the Si-B3 spectra. The analysis supports assignment of a tetra-interstitial defect as the origin of the signal.

  12. Retrospective Dosimetry: Dose Analysis From Tooth Enamel Using Electron Spin Resonance (ESR)

    International Nuclear Information System (INIS)

    Mohd Rodzi Ali; Rahimah Abdul Rahim; Noraisyah Yusof; Syed Asraf Fahlawi Wafa Syed Mohd Ghazi; Juliana Mahamad Napiah; Yahaya Talib; Rehir Dahalan

    2014-01-01

    The radiation dose should be accurately measured in order to relate its effect to the cells. The assessment of dose usually performed using biological dosimetry techniques. However, the reduction of lymphocytes (white blood cells) after the time period results in inaccuracy of dose measurement. An alternative method used is the application of Electron Spin Resonance (ESR) using tooth enamel. In this study, tooth enamels were evaluated and used to measure the individual absorbed dose from the background. The basic tooth features that would affect dose measurement were discussed. The results show this technique is capable and effective for retrospective dose measurement and useful for the study of radiation effect to human. (author)

  13. Detection of irradiated food: Electron spin resonance measurement of irradiated meat, fish and nuts

    International Nuclear Information System (INIS)

    Linke, B.; Helle, N.; Mager, M.; Schreiber, G.A.; Boegl, K.W.

    1993-01-01

    In an intercomparison study organized by the German Federal Health Office (BGA) the use of electron spin resonance (ESR) spectroscopy as a routine method according to paragraph 35 of the German Food Legislation (LMBG) was tested for bone containing meat, fish and nuts (shells). Each participating laboratory examined six chicken, six rainbow trout and four pistachio samples. The examinations were successful, only three samples were not identified correctly and moreover these mistakes were caused by misinterpretation of the ESR spectra. 13 out of 18 participating laboratories used a new routine ESR spectrometer and all samples were identified correctly with this instrument. (orig.) [de

  14. Solid state nuclear magnetic resonance: investigating the spins of nuclear related materials

    International Nuclear Information System (INIS)

    Charpentier, Th.

    2007-10-01

    The author reviews his successive research works: his research thesis work on the Multiple Quantum Magic Angle Spinning (MQMAS) which is a quadric-polar nucleus multi-quanta correlation spectroscopy method, the modelling of NMR spectra of disordered materials, the application to materials of interest for the nuclear industry (notably the glasses used for nuclear waste containment). He presents the various research projects in which he is involved: storing glasses, nuclear magnetic resonance in paramagnetism, solid hydrogen storing matrices, methodological and instrument developments in high magnetic field and high resolution solid NMR, long range distance measurement by solid state Tritium NMR (observing the structure and dynamics of biological complex systems at work)

  15. Electric-field assisted spin torque nano-oscillator and binary frequency shift keying modulation

    Science.gov (United States)

    Zhang, Xiangli; Chen, Hao-Hsuan; Zhang, Zongzhi; Liu, Yaowen

    2018-04-01

    Electric-controlled magnetization precession introduces technologically relevant possibility for developing spin torque nano-oscillators (STNO) with potential applications in microwave emission. Using the perpendicularly magnetized magnetic tunnel junction (MTJ), we show that the magnetization oscillation frequency can be tuned by the co-action of electric field and spin polarized current. The dynamical phase diagram of MTJ-based STNO is analytically predicted through coordinate transformation from the laboratory frame to the rotation frame, by which the nonstationary out-of-plane magnetization precession process is therefore transformed into the stationary process in the rotation frame. Furthermore, using this STNO as a microwave source, we numerically demonstrate that the bit signal can be transmitted by a binary frequency shift keying (BFSK) modulation technique. The BFSK scheme shows good modulation features with no transient state.

  16. Surface plasmon resonance image sensor module of spin-coated silver film with polymer layer.

    Science.gov (United States)

    Son, Jung-Han; Lee, Dong Hun; Cho, Yong-Jin; Lee, Myung-Hyun

    2013-11-01

    Prism modules of 20 nm-, 40 nm-, and 60 nm-thick spin-coated silver films both without and with an upper 100 nm-thick spin-coated polymer layer were fabricated for surface plasmon resonance (SPR) image sensor applications. The prism modules were applied to an SPR image sensor system. The coefficients of determination (R2s) for the 20 nm-, 40 nm- and 60 nm-thick silver films without the polymer layer were 0.9231, 0.9901, and 0.9889, respectively, and with the polymer layer 0.9228, 0.9951, and 0.9880, respectively when standard ethanol solutions with 0.1% intervals in the range of 20.0% to 20.5% were applied. The upper polymer layer has no effect on the R2. The prism modules of the 40-nm-thick spin-coated silver films had the highest R2 value of approximately 0.99. The durability of the 40 nm-thick spin-coated silver film with the 100 nm-thick polymer layer is much better than that without the upper low-loss polymer layer. The developed SPR image sensor module of the 40 nm-thick spin-coated silver film with the upper 100 nm-thick low-loss polymer film is expected to be a very cost-effective and robust solution because the films are formed at low temperatures in a short period of time without requiring a vacuum system and are very durable.

  17. Electron Paramagnetic Resonance Measurements of Reactive Oxygen Species by Cyclic Hydroxylamine Spin Probes.

    Science.gov (United States)

    Dikalov, Sergey I; Polienko, Yuliya F; Kirilyuk, Igor

    2017-11-17

    Oxidative stress contributes to numerous pathophysiological conditions such as development of cancer, neurodegenerative, and cardiovascular diseases. A variety of measurements of oxidative stress markers in biological systems have been developed; however, many of these methods are not specific, can produce artifacts, and do not directly detect the free radicals and reactive oxygen species (ROS) that cause oxidative stress. Electron paramagnetic resonance (EPR) is a unique tool that allows direct measurements of free radical species. Cyclic hydroxylamines are useful and convenient molecular probes that readily react with ROS to produce stable nitroxide radicals, which can be quantitatively measured by EPR. In this work, we critically review recent applications of various cyclic hydroxylamine spin probes in biology to study oxidative stress, their advantages, and the shortcomings. Recent Advances: In the past decade, a number of new cyclic hydroxylamine spin probes have been developed and their successful application for ROS measurement using EPR has been published. These new state-of-the-art methods provide improved selectivity and sensitivity for in vitro and in vivo studies. Although cyclic hydroxylamine spin probes EPR application has been previously described, there has been lack of translation of these new methods into biomedical research, limiting their widespread use. This work summarizes "best practice" in applications of cyclic hydroxylamine spin probes to assist with EPR studies of oxidative stress. Additional studies to advance hydroxylamine spin probes from the "basic science" to biomedical applications are needed and could lead to better understanding of pathological conditions associated with oxidative stress. Antioxid. Redox Signal. 00, 000-000.

  18. Theoretical consideration of spin-polarized resonant tunneling in magnetic tunnel junctions

    International Nuclear Information System (INIS)

    Mu Haifeng; Zhu Zhengang; Zheng Qingrong; Jin Biao; Wang Zhengchuan; Su Gang

    2004-01-01

    A recent elegant experimental realization [S. Yuasa et al., Science 297 (2002) 234] of the spin-polarized resonant tunneling in magnetic tunnel junctions is interpreted in terms of a two-band model. It is shown that the tunnel magnetoresistance (TMR) decays oscillatorily with the thickness of the normal metal (NM) layer, being fairly in agreement with the experimental observation. The tunnel conductance is found to decay with slight oscillations with the increase of the NM layer thickness, which is also well consistent with the experiment. In addition, when the magnetizations of both ferromagnet electrodes are not collinearly aligned, TMR is found to exhibit sharp resonant peaks at some particular thickness of the NM layer. The peaked TMR obeys nicely a Gaussian distribution against the relative orientation of the magnetizations

  19. Measurement of the Proton and Deuteron Spin Structure Function g1 in the Resonance Region

    International Nuclear Information System (INIS)

    Abe, K.; Akagi, T.; Perry Anthony; Antonov, R.; Arnold, R.G.; Todd Averett; Band, H.R.; Bauer, J.M.; Borel, H.; Peter Bosted; Vincent Breton; Button-Shafer, J.; Jian-Ping Chen; T.E. Chupp; J. Clendenin; C. Comptour; K.P. Coulter; G. Court; Donald Crabb; M. Daoudi; Donal Day; F.S. Dietrich; James Dunne; H. Dutz; R. Erbacher; J. Fellbaum; Andrew Feltham; Helene Fonvieille; Emil Frlez; D. Garvey; R. Gearhart; Javier Gomez; P. Grenier; Keith Griffioen; S. Hoeibraten; Emlyn Hughes; Charles Hyde-Wright; J.R. Johnson; D. Kawall; Andreas Klein; Sebastian Kuhn; M. Kuriki; Richard Lindgren; T.J. Liu; R.M. Lombard-Nelsen; Jacques Marroncle; Tomoyuki Maruyama; X.K. Maruyama; James Mccarthy; Werner Meyer; Zein-Eddine Meziani; Ralph Minehart; Joseph Mitchell; J. Morgenstern; Gerassimos Petratos; R. Pitthan; Dinko Pocanic; C. Prescott; R. Prepost; P. Raines; Brian Raue; D. Reyna; A. Rijllart; Yves Roblin; L. Rochester; Stephen Rock; Oscar Rondon-Aramayo; Ingo Sick; Lee Smith; Tim Smith; M. Spengos; F. Staley; P. Steiner; S. St. Lorant; L.M. Stuart; F. Suekane; Z.M. Szalata; Huabin Tang; Y. Terrien; Tracy Usher; Dieter Walz; Frank Wesselmann; J.L. White; K. Witte; C. Young; Brad Youngman; Haruo Yuta; G. Zapalac; Benedikt Zihlmann; Zimmermann, D.

    1997-01-01

    We have measured the proton and deuteron spin structure functions g 1 p and g 1 d in the region of the nucleon resonances for W 2 2 and Q 2 ≅ 0.5 and Q 2 ≅ 1.2 GeV 2 by inelastically scattering 9.7 GeV polarized electrons off polarized 15 NH 3 and 15 ND 3 targets. We observe significant structure in g 1 p in the resonance region. We have used the present results, together with the deep-inelastic data at higher W 2 , to extract Γ(Q 2 ) (triple b ond) ∫ 0 1 g 1 (x,Q 2 ) dx. This is the first information on the low-Q 2 evolution of Gamma toward the Gerasimov-Drell-Hearn limit at Q 2 = 0

  20. Generation of THz frequency using PANDA ring resonator for THz imaging

    Science.gov (United States)

    Jalil, MA; Abdolkarim, Afroozeh; Saktioto, T; Ong, CT; Yupapin, Preecha P

    2012-01-01

    In this study, we have generated terahertz (THz) frequency by a novel design of microring resonators for medical applications. The dense wavelength-division multiplexing can be generated and obtained by using a Gaussian pulse propagating within a modified PANDA ring resonator and an add/drop filter system. Our results show that the THz frequency region can be obtained between 40–50 THz. This area of frequency provides a reliable frequency band for THz pulsed imaging. PMID:22359455

  1. Effects of air susceptibility on proton resonance frequency MR thermometry.

    Science.gov (United States)

    Streicher, Markus N; Schäfer, Andreas; Reimer, Enrico; Dhital, Bibek; Trampel, Robert; Ivanov, Dimo; Turner, Robert

    2012-02-01

    The temperature dependence of the proton resonance frequency (PRF) is often used in MR thermometry. However, this method is prone to even very small changes in local magnetic field strength. Here, we report on the effects of susceptibility changes of surrounding air on the magnetic field inside an object and their inferred effect on the measured MR temperature. MR phase thermometry was performed on spherical agar phantoms enclosed in cylindrical containers at 7 T. The air susceptibility inside the cylindrical container was changed by both heating the air and changing the gas composition. Changing the temperature of surrounding air from 23 to 69°C caused an apparent MR temperature error of 2 K. When ambient air was displaced by 100% oxygen, the MR temperature error increased to 40 K. The magnetic field shift and therefore error in inferred MR temperature scales linearly with volume susceptibility change and has a strong and nontrivial dependence on the experimental configuration. Air susceptibility changes associated with oxygen concentration changes greatly affect PRF MR thermometry measurements. Air temperature changes can also affect these measurements, but to a smaller degree. For uncalibrated MR thermometry, air susceptibility changes may be a significant source of error.

  2. Electron spin resonance insight into broadband absorption of the Cu3Bi(SeO32O2Br metamagnet

    Directory of Open Access Journals (Sweden)

    A. Zorko

    2016-05-01

    Full Text Available Metamagnets, which exhibit a transition from a low-magnetization to a high-magnetization state induced by the applied magnetic field, have recently been highlighted as promising materials for controllable broadband absorption. Here we show results of a multifrequency electron spin resonance (ESR investigation of the Cu3Bi(SeO32O2Br planar metamagnet on the kagome lattice. Its mixed antiferromagnetic/ferromagnetic phase is stabilized in a finite range of applied fields around 0.8 T at low temperatures and is characterized by enhanced microwave absorption. The absorption signal is non-resonant and its boundaries correspond to two critical fields that determine the mixed phase. With decreasing temperature these increase like the sublattice magnetization of the antiferromagnetic phase and show no frequency dependence between 100 and 480 GHz. On the contrary, we find that the critical fields depend on the magnetic-field sweeping direction. In particular, the higher critical field, which corresponds to the transition from the mixed to the ferromagnetic phase, shows a pronounced hysteresis effect, while such a hysteresis is absent for the lower critical field. The observed hysteresis is enhanced at lower temperatures, which suggests that thermal fluctuations play an important role in destabilizing the highly absorbing mixed phase.

  3. Viscoelastic effects on frequency tuning of a dielectric elastomer membrane resonator

    International Nuclear Information System (INIS)

    Zhou, Jianyou; Jiang, Liying; Khayat, Roger E.

    2014-01-01

    As a recent application of dielectric elastomers (DEs), DE resonators have become an alternative to conventional silicon-based resonators used in MEMS and have attracted much interest from the research community. However, most existing modeling works for the DE resonators ignore the intrinsic viscoelastic effect of the material that may strongly influence their dynamic performance. Based on the finite-deformation viscoelasticity theory for dielectrics, this paper theoretically examines the in-plane oscillation of a DE membrane resonator to demonstrate how the material viscoelasticity affects the actuation and frequency tuning processes of the resonator. From the simulation results, it is concluded that not only the applied voltage can change the natural frequency of the resonator, but also the inelastic deformation contributes to frequency tuning. Due to the viscoelasticity of the material, the electrical loading rate influences the actuation process of the DE resonator, while it has little effect on the final steady frequency tuned by the prescribed voltage within the safety range. With the consideration of the typical failure modes of the resonator and the evolution process of the material, the tunable frequency range and the safe range of the applied voltage of the DE membrane resonator with different dimension parameters are determined in this work, which are found to be dependent on the electrical loading rate. This work is expected to provide a better understanding on the frequency tuning of viscoelastic DE membrane resonators and a guideline for the design of DE devices

  4. Noise Depression of Parasitic Capacitance for Frequency Detection of Micromechanical Bulk Disk Resonator

    DEFF Research Database (Denmark)

    Tang, Meng; Cagliani, Alberto; Escouflaire, Marie

    2010-01-01

    A bulk disk resonator working in dynamic mode is used for mass detection. In the capacitive transduction scheme, the parasitic capacitance between the electrodes produces an anti resonance in the transmission curve, which distorts the phase shift at the resonant frequency and increases the freque...

  5. Electron Spin Resonance and optical absorption spectroscopic studies of manganese centers in aluminium lead borate glasses.

    Science.gov (United States)

    SivaRamaiah, G; LakshmanaRao, J

    2012-12-01

    Electron Spin Resonance (ESR) and optical absorption studies of 5Al(2)O(3)+75H(3)BO(3)+(20-x)PbO+xMnSO(4) (where x=0.5, 1,1.5 and 2 mol% of MnSO(4)) glasses at room temperature have been studied. The ESR spectrum of all the glasses exhibits resonance signals with effective isotropic g values at ≈2.0, 3.3 and 4.3. The ESR resonance signal at isotropic g≈2.0 has been attributed to Mn(2+) centers in an octahedral symmetry. The ESR resonance signals at isotropic g≈3.3 and 4.3 have been attributed to the rhombic symmetry of the Mn(2+) ions. The zero-field splitting parameter (zfs) has been calculated from the intensities of the allowed hyperfine lines. The optical absorption spectrum exhibits an intense band in the visible region and it has been attributed to (5)E(g)→(5)T(2g) transition of Mn(3+)centers in an octahedral environment. The optical band gap and the Urbach energies have been calculated from the ultraviolet absorption edges. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Signal interferences from turbulent spin dynamics in solution nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    Huang, Susie Y.; Lin, Yung-Ya; Lisitza, Natalia; Warren, Warren S.

    2002-06-01

    Artifacts arising from aperiodic turbulent spin dynamics in gradient-based nuclear magnetic resonance (NMR) applications are comprehensively surveyed and numerically simulated by a nonlinear Bloch equation. The unexpected dynamics, triggered by the joint action of radiation damping and the distant dipolar field, markedly deteriorate the performance of certain pulse sequences incorporating weak pulsed-field gradients and long evolution times. The effects are demonstrated in three general classes of gradient NMR applications: solvent signal suppression, diffusion measurements, and coherence pathway selection. Gradient-modulated solvent transverse magnetization can be partially rephased in a series of self-refocusing gradient echoes that blank out solute resonances in the CHESS (chemical-shift-selective spectroscopy) and WATERGATE (gradient-tailored water suppression) solvent suppression schemes. In addition, the discovered dynamics contribute to erratic echo attenuation in pulsed gradient spin echo (PGSE) and PGSE stimulated echo diffusion measurements and produce coherence leakage in gradient-selected DQFCOSY and HMQC experiments. Specific remedies for minimizing unwanted effects are presented.

  7. Air oxidation of the kerogen/asphaltene vanadyl porphyrins: an electron spin resonance study

    Directory of Open Access Journals (Sweden)

    MIRJANA S. PAVLOVIC

    2000-02-01

    Full Text Available The thermal behavior of vanadyl porphyrins was studied by electron spin resonance during heating of kerogens, isolated from the La Luna (Venezuela and Serpiano (Switzerland bituminous rocks, at 25°C for 1 to 20 days in the presence of air. During the thermal treatment of the kerogens, the vanadyl porphyrins resonance signals decrease monotonically and become quite small after 6 days of heating. Concomitantly, new vanadyl signals appear and, at longer heating times, dominate the spectrum. It is suggested that the secondary vanadyl species must have been formed from vanadyl porphyrins. Similar conversions of vanadyl porphyrins are observed under the same experimental conditions for asphaltenes extracted from the La Luna and Serpiano rocks, and floating asphalt from the Dead Sea (Israel. A comparison of the spin-Hamiltonian parameters for vanadyl porphyrins and the vanadyl compounds obtained during pyrolysis of the kerogens/asphaltenes suggests that the latter are of a non-porphyrin type. For comparison a study was conducted on Western Kentucky No. 9 coal enriched with vanadium (>>400 ppm from six mines. All the coal samples show only the presence of predominant by non-porphyrin vanadyl compounds, similar to those generated through laboratory heating of the kerogens/asphaltenes in air. In addition, some samples also contain a minor amount of vanadyl porphyrins.

  8. Resonant Spin Excitations in Unconventional Heavy Fermion Superconductors and Kondo Lattice Compounds

    Science.gov (United States)

    Thalmeier, Peter; Akbari, Alireza

    2015-07-01

    The heavy quasiparticle bands in Kondo materials which originate in the hybridization of f- and conduction electrons exhibit numerous, sometimes coexisting, broken symmetry phases. Most notable are unconventional superconductivity, itinerant small moment antiferromagnetism and hidden order of higher order multipoles of f-electrons which all lead to a gapping of the heavy bands. In rare cases the chemical potential lies within the hybridization gap and the ground state is a Kondo semiconductor without ordering. The dynamical magnetic response of such gapped f-electron systems has been investigated with inelastic neutron scattering. It was found that collective spin exciton modes which are due to residual quasiparticle interactions appear below the threshold of superconducting or hidden order gap or directly the hybridzation gap . The spin exciton resonance is commonly located around a zone boundary vector Q with nesting properties in the normal state. In the superconducting case its appearance gives a strong criterion for the gap symmetry requesting a sign change Δk+Q = -Δk due to the coherence factors. Therefore this many body effect with fundamental importance may also be used as a tool to discriminate between proposed gap models. While the spin resonance has been observed for many compounds we restrict our discussion here exclusively to the small group of f-electron superconductors CeCoIn5, CeCu2Si2 and UPd2Al3, hidden order Kondo compounds CeB6 and URu2Si2 as well as the Kondo semiconductor YbB12.

  9. Observation of overlapping spin-1 and spin-3 $\\overline{D}^0 K^-$ resonances at mass $2.86 {\\rm GeV}/c^2$

    CERN Document Server

    Aaij, Roel; Adinolfi, Marco; Affolder, Anthony; Ajaltouni, Ziad; Akar, Simon; Albrecht, Johannes; Alessio, Federico; Alexander, Michael; Ali, Suvayu; Alkhazov, Georgy; Alvarez Cartelle, Paula; Alves Jr, Antonio Augusto; Amato, Sandra; Amerio, Silvia; Amhis, Yasmine; An, Liupan; Anderlini, Lucio; Anderson, Jonathan; Andreassen, Rolf; Andreotti, Mirco; Andrews, Jason; Appleby, Robert; Aquines Gutierrez, Osvaldo; Archilli, Flavio; Artamonov, Alexander; Artuso, Marina; Aslanides, Elie; Auriemma, Giulio; Baalouch, Marouen; Bachmann, Sebastian; Back, John; Badalov, Alexey; Baesso, Clarissa; Baldini, Wander; Barlow, Roger; Barschel, Colin; Barsuk, Sergey; Barter, William; Batozskaya, Varvara; Battista, Vincenzo; Bay, Aurelio; Beaucourt, Leo; Beddow, John; Bedeschi, Franco; Bediaga, Ignacio; Belogurov, Sergey; Belous, Konstantin; Belyaev, Ivan; Ben-Haim, Eli; Bencivenni, Giovanni; Benson, Sean; Benton, Jack; Berezhnoy, Alexander; Bernet, Roland; Bettler, Marc-Olivier; van Beuzekom, Martinus; Bien, Alexander; Bifani, Simone; Bird, Thomas; Bizzeti, Andrea; Bjørnstad, Pål Marius; Blake, Thomas; Blanc, Frédéric; Blouw, Johan; Blusk, Steven; Bocci, Valerio; Bondar, Alexander; Bondar, Nikolay; Bonivento, Walter; Borghi, Silvia; Borgia, Alessandra; Borsato, Martino; Bowcock, Themistocles; Bowen, Espen Eie; Bozzi, Concezio; Brambach, Tobias; van den Brand, Johannes; Bressieux, Joël; Brett, David; Britsch, Markward; Britton, Thomas; Brodzicka, Jolanta; Brook, Nicholas; Brown, Henry; Bursche, Albert; Busetto, Giovanni; Buytaert, Jan; Cadeddu, Sandro; Calabrese, Roberto; Calvi, Marta; Calvo Gomez, Miriam; Campana, Pierluigi; Campora Perez, Daniel; Carbone, Angelo; Carboni, Giovanni; Cardinale, Roberta; Cardini, Alessandro; Carson, Laurence; Carvalho Akiba, Kazuyoshi; Casse, Gianluigi; Cassina, Lorenzo; Castillo Garcia, Lucia; Cattaneo, Marco; Cauet, Christophe; Cenci, Riccardo; Charles, Matthew; Charpentier, Philippe; Chefdeville, Maximilien; Chen, Shanzhen; Cheung, Shu-Faye; Chiapolini, Nicola; Chrzaszcz, Marcin; Ciba, Krzystof; Cid Vidal, Xabier; Ciezarek, Gregory; Clarke, Peter; Clemencic, Marco; Cliff, Harry; Closier, Joel; Coco, Victor; Cogan, Julien; Cogneras, Eric; Collins, Paula; Comerma-Montells, Albert; Contu, Andrea; Cook, Andrew; Coombes, Matthew; Coquereau, Samuel; Corti, Gloria; Corvo, Marco; Counts, Ian; Couturier, Benjamin; Cowan, Greig; Craik, Daniel Charles; Cruz Torres, Melissa Maria; Cunliffe, Samuel; Currie, Robert; D'Ambrosio, Carmelo; Dalseno, Jeremy; David, Pascal; David, Pieter; Davis, Adam; De Bruyn, Kristof; De Capua, Stefano; De Cian, Michel; De Miranda, Jussara; De Paula, Leandro; De Silva, Weeraddana; De Simone, Patrizia; Decamp, Daniel; Deckenhoff, Mirko; Del Buono, Luigi; Déléage, Nicolas; Derkach, Denis; Deschamps, Olivier; Dettori, Francesco; Di Canto, Angelo; Dijkstra, Hans; Donleavy, Stephanie; Dordei, Francesca; Dorigo, Mirco; Dosil Suárez, Alvaro; Dossett, David; Dovbnya, Anatoliy; Dreimanis, Karlis; Dujany, Giulio; Dupertuis, Frederic; Durante, Paolo; Dzhelyadin, Rustem; Dziurda, Agnieszka; Dzyuba, Alexey; Easo, Sajan; Egede, Ulrik; Egorychev, Victor; Eidelman, Semen; Eisenhardt, Stephan; Eitschberger, Ulrich; Ekelhof, Robert; Eklund, Lars; El Rifai, Ibrahim; Elsasser, Christian; Ely, Scott; Esen, Sevda; Evans, Hannah Mary; Evans, Timothy; Falabella, Antonio; Färber, Christian; Farinelli, Chiara; Farley, Nathanael; Farry, Stephen; Fay, Robert; Ferguson, Dianne; Fernandez Albor, Victor; Ferreira Rodrigues, Fernando; Ferro-Luzzi, Massimiliano; Filippov, Sergey; Fiore, Marco; Fiorini, Massimiliano; Firlej, Miroslaw; Fitzpatrick, Conor; Fiutowski, Tomasz; Fontana, Marianna; Fontanelli, Flavio; Forty, Roger; Francisco, Oscar; Frank, Markus; Frei, Christoph; Frosini, Maddalena; Fu, Jinlin; Furfaro, Emiliano; Gallas Torreira, Abraham; Galli, Domenico; Gallorini, Stefano; Gambetta, Silvia; Gandelman, Miriam; Gandini, Paolo; Gao, Yuanning; García Pardiñas, Julián; Garofoli, Justin; Garra Tico, Jordi; Garrido, Lluis; Gaspar, Clara; Gauld, Rhorry; Gavardi, Laura; Gavrilov, Gennadii; Geraci, Angelo; Gersabeck, Evelina; Gersabeck, Marco; Gershon, Timothy; Ghez, Philippe; Gianelle, Alessio; Gianì, Sebastiana; Gibson, Valerie; Giubega, Lavinia-Helena; Gligorov, Vladimir; Göbel, Carla; Golubkov, Dmitry; Golutvin, Andrey; Gomes, Alvaro; Gotti, Claudio; Grabalosa Gándara, Marc; Graciani Diaz, Ricardo; Granado Cardoso, Luis Alberto; Graugés, Eugeni; Graziani, Giacomo; Grecu, Alexandru; Greening, Edward; Gregson, Sam; Griffith, Peter; Grillo, Lucia; Grünberg, Oliver; Gui, Bin; Gushchin, Evgeny; Guz, Yury; Gys, Thierry; Hadjivasiliou, Christos; Haefeli, Guido; Haen, Christophe; Haines, Susan; Hall, Samuel; Hamilton, Brian; Hampson, Thomas; Han, Xiaoxue; Hansmann-Menzemer, Stephanie; Harnew, Neville; Harnew, Samuel; Harrison, Jonathan; He, Jibo; Head, Timothy; Heijne, Veerle; Hennessy, Karol; Henrard, Pierre; Henry, Louis; Hernando Morata, Jose Angel; van Herwijnen, Eric; Heß, Miriam; Hicheur, Adlène; Hill, Donal; Hoballah, Mostafa; Hombach, Christoph; Hulsbergen, Wouter; Hunt, Philip; Hussain, Nazim; Hutchcroft, David; Hynds, Daniel; Idzik, Marek; Ilten, Philip; Jacobsson, Richard; Jaeger, Andreas; Jalocha, Pawel; Jans, Eddy; Jaton, Pierre; Jawahery, Abolhassan; Jing, Fanfan; John, Malcolm; Johnson, Daniel; Jones, Christopher; Joram, Christian; Jost, Beat; Jurik, Nathan; Kaballo, Michael; Kandybei, Sergii; Kanso, Walaa; Karacson, Matthias; Karbach, Moritz; Karodia, Sarah; Kelsey, Matthew; Kenyon, Ian; Ketel, Tjeerd; Khanji, Basem; Khurewathanakul, Chitsanu; Klaver, Suzanne; Klimaszewski, Konrad; Kochebina, Olga; Kolpin, Michael; Komarov, Ilya; Koopman, Rose; Koppenburg, Patrick; Korolev, Mikhail; Kozlinskiy, Alexandr; Kravchuk, Leonid; Kreplin, Katharina; Kreps, Michal; Krocker, Georg; Krokovny, Pavel; Kruse, Florian; Kucewicz, Wojciech; Kucharczyk, Marcin; Kudryavtsev, Vasily; Kurek, Krzysztof; Kvaratskheliya, Tengiz; La Thi, Viet Nga; Lacarrere, Daniel; Lafferty, George; Lai, Adriano; Lambert, Dean; Lambert, Robert W; Lanfranchi, Gaia; Langenbruch, Christoph; Langhans, Benedikt; Latham, Thomas; Lazzeroni, Cristina; Le Gac, Renaud; van Leerdam, Jeroen; Lees, Jean-Pierre; Lefèvre, Regis; Leflat, Alexander; Lefrançois, Jacques; Leo, Sabato; Leroy, Olivier; Lesiak, Tadeusz; Leverington, Blake; Li, Yiming; Likhomanenko, Tatiana; Liles, Myfanwy; Lindner, Rolf; Linn, Christian; Lionetto, Federica; Liu, Bo; Lohn, Stefan; Longstaff, Iain; Lopes, Jose; Lopez-March, Neus; Lowdon, Peter; Lu, Haiting; Lucchesi, Donatella; Luo, Haofei; Lupato, Anna; Luppi, Eleonora; Lupton, Oliver; Machefert, Frederic; Machikhiliyan, Irina V; Maciuc, Florin; Maev, Oleg; Malde, Sneha; Malinin, Alexander; Manca, Giulia; Mancinelli, Giampiero; Mapelli, Alessandro; Maratas, Jan; Marchand, Jean François; Marconi, Umberto; Marin Benito, Carla; Marino, Pietro; Märki, Raphael; Marks, Jörg; Martellotti, Giuseppe; Martens, Aurelien; Martín Sánchez, Alexandra; Martinelli, Maurizio; Martinez Santos, Diego; Martinez Vidal, Fernando; Martins Tostes, Danielle; Massafferri, André; Matev, Rosen; Mathe, Zoltan; Matteuzzi, Clara; Mazurov, Alexander; McCann, Michael; McCarthy, James; McNab, Andrew; McNulty, Ronan; McSkelly, Ben; Meadows, Brian; Meier, Frank; Meissner, Marco; Merk, Marcel; Milanes, Diego Alejandro; Minard, Marie-Noelle; Moggi, Niccolò; Molina Rodriguez, Josue; Monteil, Stephane; Morandin, Mauro; Morawski, Piotr; Mordà, Alessandro; Morello, Michael Joseph; Moron, Jakub; Morris, Adam Benjamin; Mountain, Raymond; Muheim, Franz; Müller, Katharina; Mussini, Manuel; Muster, Bastien; Naik, Paras; Nakada, Tatsuya; Nandakumar, Raja; Nasteva, Irina; Needham, Matthew; Neri, Nicola; Neubert, Sebastian; Neufeld, Niko; Neuner, Max; Nguyen, Anh Duc; Nguyen, Thi-Dung; Nguyen-Mau, Chung; Nicol, Michelle; Niess, Valentin; Niet, Ramon; Nikitin, Nikolay; Nikodem, Thomas; Novoselov, Alexey; O'Hanlon, Daniel Patrick; Oblakowska-Mucha, Agnieszka; Obraztsov, Vladimir; Oggero, Serena; Ogilvy, Stephen; Okhrimenko, Oleksandr; Oldeman, Rudolf; Onderwater, Gerco; Orlandea, Marius; Otalora Goicochea, Juan Martin; Owen, Patrick; Oyanguren, Maria Arantza; Pal, Bilas Kanti; Palano, Antimo; Palombo, Fernando; Palutan, Matteo; Panman, Jacob; Papanestis, Antonios; Pappagallo, Marco; Pappalardo, Luciano; Parkes, Christopher; Parkinson, Christopher John; Passaleva, Giovanni; Patel, Girish; Patel, Mitesh; Patrignani, Claudia; Pazos Alvarez, Antonio; Pearce, Alex; Pellegrino, Antonio; Pepe Altarelli, Monica; Perazzini, Stefano; Perez Trigo, Eliseo; Perret, Pascal; Perrin-Terrin, Mathieu; Pescatore, Luca; Pesen, Erhan; Petridis, Konstantin; Petrolini, Alessandro; Picatoste Olloqui, Eduardo; Pietrzyk, Boleslaw; Pilař, Tomas; Pinci, Davide; Pistone, Alessandro; Playfer, Stephen; Plo Casasus, Maximo; Polci, Francesco; Poluektov, Anton; Polycarpo, Erica; Popov, Alexander; Popov, Dmitry; Popovici, Bogdan; Potterat, Cédric; Price, Eugenia; Prisciandaro, Jessica; Pritchard, Adrian; Prouve, Claire; Pugatch, Valery; Puig Navarro, Albert; Punzi, Giovanni; Qian, Wenbin; Rachwal, Bartolomiej; Rademacker, Jonas; Rakotomiaramanana, Barinjaka; Rama, Matteo; Rangel, Murilo; Raniuk, Iurii; Rauschmayr, Nathalie; Raven, Gerhard; Reichert, Stefanie; Reid, Matthew; dos Reis, Alberto; Ricciardi, Stefania; Richards, Sophie; Rihl, Mariana; Rinnert, Kurt; Rives Molina, Vincente; Roa Romero, Diego; Robbe, Patrick; Rodrigues, Ana Barbara; Rodrigues, Eduardo; Rodriguez Perez, Pablo; Roiser, Stefan; Romanovsky, Vladimir; Romero Vidal, Antonio; Rotondo, Marcello; Rouvinet, Julien; Ruf, Thomas; Ruffini, Fabrizio; Ruiz, Hugo; Ruiz Valls, Pablo; Saborido Silva, Juan Jose; Sagidova, Naylya; Sail, Paul; Saitta, Biagio; Salustino Guimaraes, Valdir; Sanchez Mayordomo, Carlos; Sanmartin Sedes, Brais; Santacesaria, Roberta; Santamarina Rios, Cibran; Santovetti, Emanuele; Sarti, Alessio; Satriano, Celestina; Satta, Alessia; Saunders, Daniel Martin; Savrie, Mauro; Savrina, Darya; Schiller, Manuel; Schindler, Heinrich; Schlupp, Maximilian; Schmelling, Michael; Schmidt, Burkhard; Schneider, Olivier; Schopper, Andreas; Schune, Marie Helene; Schwemmer, Rainer; Sciascia, Barbara; Sciubba, Adalberto; Seco, Marcos; Semennikov, Alexander; Sepp, Indrek; Serra, Nicola; Serrano, Justine; Sestini, Lorenzo; Seyfert, Paul; Shapkin, Mikhail; Shapoval, Illya; Shcheglov, Yury; Shears, Tara; Shekhtman, Lev; Shevchenko, Vladimir; Shires, Alexander; Silva Coutinho, Rafael; Simi, Gabriele; Sirendi, Marek; Skidmore, Nicola; Skwarnicki, Tomasz; Smith, Anthony; Smith, Edmund; Smith, Eluned; Smith, Jackson; Smith, Mark; Snoek, Hella; Sokoloff, Michael; Soler, Paul; Soomro, Fatima; Souza, Daniel; Souza De Paula, Bruno; Spaan, Bernhard; Sparkes, Ailsa; Spradlin, Patrick; Sridharan, Srikanth; Stagni, Federico; Stahl, Marian; Stahl, Sascha; Steinkamp, Olaf; Stenyakin, Oleg; Stevenson, Scott; Stoica, Sabin; Stone, Sheldon; Storaci, Barbara; Stracka, Simone; Straticiuc, Mihai; Straumann, Ulrich; Stroili, Roberto; Subbiah, Vijay Kartik; Sun, Liang; Sutcliffe, William; Swientek, Krzysztof; Swientek, Stefan; Syropoulos, Vasileios; Szczekowski, Marek; Szczypka, Paul; Szilard, Daniela; Szumlak, Tomasz; T'Jampens, Stephane; Teklishyn, Maksym; Tellarini, Giulia; Teubert, Frederic; Thomas, Christopher; Thomas, Eric; van Tilburg, Jeroen; Tisserand, Vincent; Tobin, Mark; Tolk, Siim; Tomassetti, Luca; Tonelli, Diego; Topp-Joergensen, Stig; Torr, Nicholas; Tournefier, Edwige; Tourneur, Stephane; Tran, Minh Tâm; Tresch, Marco; Tsaregorodtsev, Andrei; Tsopelas, Panagiotis; Tuning, Niels; Ubeda Garcia, Mario; Ukleja, Artur; Ustyuzhanin, Andrey; Uwer, Ulrich; Vagnoni, Vincenzo; Valenti, Giovanni; Vallier, Alexis; Vazquez Gomez, Ricardo; Vazquez Regueiro, Pablo; Vázquez Sierra, Carlos; Vecchi, Stefania; Velthuis, Jaap; Veltri, Michele; Veneziano, Giovanni; Vesterinen, Mika; Viaud, Benoit; Vieira, Daniel; Vieites Diaz, Maria; Vilasis-Cardona, Xavier; Vollhardt, Achim; Volyanskyy, Dmytro; Voong, David; Vorobyev, Alexey; Vorobyev, Vitaly; Voß, Christian; Voss, Helge; de Vries, Jacco; Waldi, Roland; Wallace, Charlotte; Wallace, Ronan; Walsh, John; Wandernoth, Sebastian; Wang, Jianchun; Ward, David; Watson, Nigel; Websdale, David; Whitehead, Mark; Wicht, Jean; Wiedner, Dirk; Wilkinson, Guy; Williams, Matthew; Williams, Mike; Wilson, Fergus; Wimberley, Jack; Wishahi, Julian; Wislicki, Wojciech; Witek, Mariusz; Wormser, Guy; Wotton, Stephen; Wright, Simon; Wu, Suzhi; Wyllie, Kenneth; Xie, Yuehong; Xing, Zhou; Xu, Zhirui; Yang, Zhenwei; Yuan, Xuhao; Yushchenko, Oleg; Zangoli, Maria; Zavertyaev, Mikhail; Zhang, Liming; Zhang, Wen Chao; Zhang, Yanxi; Zhelezov, Alexey; Zhokhov, Anatoly; Zhong, Liang; Zvyagin, Alexander

    2014-01-01

    The resonant substructure of $B_s^0 \\rightarrow \\overline{D}^0 K^- \\pi^+$ decays is studied using a data sample corresponding to an integrated luminosity of $3.0\\,{\\rm fb}^{-1}$ of $pp$ collision data recorded by the LHCb detector. An excess at $m(\\overline{D}^0 K^-) \\approx 2.86 {\\rm GeV}/c^2$ is found to be an admixture of spin-1 and spin-3 resonances. Therefore the $D^*_{sJ}(2860)^-$ state previously observed in inclusive $e^+e^- \\rightarrow \\overline{D}^0 K^- X$ and $pp \\rightarrow \\overline{D}^0 K^- X$ processes consists of at least two particles. This is the first observation of a heavy flavoured spin-3 resonance, and the first time that any spin-3 particle has been seen to be produced in $B$ decays. The masses and widths of the new states and of the $D^*_{s2}(2573)^-$ meson are measured, giving the most precise determinations to date.

  10. Observation of overlapping spin-1 and spin-3 D0K- resonances at mass 2.86 GeV/c2.

    Science.gov (United States)

    Aaij, R; Adeva, B; Adinolfi, M; Affolder, A; Ajaltouni, Z; Akar, S; Albrecht, J; Alessio, F; Alexander, M; Ali, S; Alkhazov, G; Alvarez Cartelle, P; Alves, A A; Amato, S; Amerio, S; Amhis, Y; An, L; Anderlini, L; Anderson, J; Andreassen, R; Andreotti, M; Andrews, J E; Appleby, R B; Aquines Gutierrez, O; Archilli, F; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Baalouch, M; Bachmann, S; Back, J J; Badalov, A; Baesso, C; Baldini, W; Barlow, R J; Barschel, C; Barsuk, S; Barter, W; Batozskaya, V; Battista, V; Bay, A; Beaucourt, L; Beddow, J; Bedeschi, F; Bediaga, I; Belogurov, S; Belous, K; Belyaev, I; Ben-Haim, E; Bencivenni, G; Benson, S; Benton, J; Berezhnoy, A; Bernet, R; Bettler, M-O; van Beuzekom, M; Bien, A; Bifani, S; Bird, T; Bizzeti, A; Bjørnstad, P M; Blake, T; Blanc, F; Blouw, J; Blusk, S; Bocci, V; Bondar, A; Bondar, N; Bonivento, W; Borghi, S; Borgia, A; Borsato, M; Bowcock, T J V; Bowen, E; Bozzi, C; Brambach, T; van den Brand, J; Bressieux, J; Brett, D; Britsch, M; Britton, T; Brodzicka, J; Brook, N H; Brown, H; Bursche, A; Busetto, G; Buytaert, J; Cadeddu, S; Calabrese, R; Calvi, M; Calvo Gomez, M; Campana, P; Campora Perez, D; Carbone, A; Carboni, G; Cardinale, R; Cardini, A; Carson, L; Carvalho Akiba, K; Casse, G; Cassina, L; Castillo Garcia, L; Cattaneo, M; Cauet, Ch; Cenci, R; Charles, M; Charpentier, Ph; Chefdeville, M; Chen, S; Cheung, S-F; Chiapolini, N; Chrzaszcz, M; Ciba, K; Cid Vidal, X; Ciezarek, G; Clarke, P E L; Clemencic, M; Cliff, H V; Closier, J; Coco, V; Cogan, J; Cogneras, E; Collins, P; Comerma-Montells, A; Contu, A; Cook, A; Coombes, M; Coquereau, S; Corti, G; Corvo, M; Counts, I; Couturier, B; Cowan, G A; Craik, D C; Cruz Torres, M; Cunliffe, S; Currie, R; D'Ambrosio, C; Dalseno, J; David, P; David, P N Y; Davis, A; De Bruyn, K; De Capua, S; De Cian, M; De Miranda, J M; De Paula, L; De Silva, W; De Simone, P; Decamp, D; Deckenhoff, M; Del Buono, L; Déléage, N; Derkach, D; Deschamps, O; Dettori, F; Di Canto, A; Dijkstra, H; Donleavy, S; Dordei, F; Dorigo, M; Dosil Suárez, A; Dossett, D; Dovbnya, A; Dreimanis, K; Dujany, G; Dupertuis, F; Durante, P; Dzhelyadin, R; Dziurda, A; Dzyuba, A; Easo, S; Egede, U; Egorychev, V; Eidelman, S; Eisenhardt, S; Eitschberger, U; Ekelhof, R; Eklund, L; El Rifai, I; Elsasser, Ch; Ely, S; Esen, S; Evans, H-M; Evans, T; Falabella, A; Färber, C; Farinelli, C; Farley, N; Farry, S; Fay, Rf; Ferguson, D; Fernandez Albor, V; Ferreira Rodrigues, F; Ferro-Luzzi, M; Filippov, S; Fiore, M; Fiorini, M; Firlej, M; Fitzpatrick, C; Fiutowski, T; Fontana, M; Fontanelli, F; Forty, R; Francisco, O; Frank, M; Frei, C; Frosini, M; Fu, J; Furfaro, E; Gallas Torreira, A; Galli, D; Gallorini, S; Gambetta, S; Gandelman, M; Gandini, P; Gao, Y; García Pardiñas, J; Garofoli, J; Garra Tico, J; Garrido, L; Gaspar, C; Gauld, R; Gavardi, L; Gavrilov, G; Geraci, A; Gersabeck, E; Gersabeck, M; Gershon, T; Ghez, Ph; Gianelle, A; Gianì, S; Gibson, V; Giubega, L; Gligorov, V V; Göbel, C; Golubkov, D; Golutvin, A; Gomes, A; Gotti, C; Grabalosa Gándara, M; Graciani Diaz, R; Granado Cardoso, L A; Graugés, E; Graziani, G; Grecu, A; Greening, E; Gregson, S; Griffith, P; Grillo, L; Grünberg, O; Gui, B; Gushchin, E; Guz, Yu; Gys, T; Hadjivasiliou, C; Haefeli, G; Haen, C; Haines, S C; Hall, S; Hamilton, B; Hampson, T; Han, X; Hansmann-Menzemer, S; Harnew, N; Harnew, S T; Harrison, J; He, J; Head, T; Heijne, V; Hennessy, K; Henrard, P; Henry, L; Hernando Morata, J A; van Herwijnen, E; Heß, M; Hicheur, A; Hill, D; Hoballah, M; Hombach, C; Hulsbergen, W; Hunt, P; Hussain, N; Hutchcroft, D; Hynds, D; Idzik, M; Ilten, P; Jacobsson, R; Jaeger, A; Jalocha, J; Jans, E; Jaton, P; Jawahery, A; Jing, F; John, M; Johnson, D; Jones, C R; Joram, C; Jost, B; Jurik, N; Kaballo, M; Kandybei, S; Kanso, W; Karacson, M; Karbach, T M; Karodia, S; Kelsey, M; Kenyon, I R; Ketel, T; Khanji, B; Khurewathanakul, C; Klaver, S; Klimaszewski, K; Kochebina, O; Kolpin, M; Komarov, I; Koopman, R F; Koppenburg, P; Korolev, M; Kozlinskiy, A; Kravchuk, L; Kreplin, K; Kreps, M; Krocker, G; Krokovny, P; Kruse, F; Kucewicz, W; Kucharczyk, M; Kudryavtsev, V; Kurek, K; Kvaratskheliya, T; La Thi, V N; Lacarrere, D; Lafferty, G; Lai, A; Lambert, D; Lambert, R W; Lanfranchi, G; Langenbruch, C; Langhans, B; Latham, T; Lazzeroni, C; Le Gac, R; van Leerdam, J; Lees, J-P; Lefèvre, R; Leflat, A; Lefrançois, J; Leo, S; Leroy, O; Lesiak, T; Leverington, B; Li, Y; Likhomanenko, T; Liles, M; Lindner, R; Linn, C; Lionetto, F; Liu, B; Lohn, S; Longstaff, I; Lopes, J H; Lopez-March, N; Lowdon, P; Lu, H; Lucchesi, D; Luo, H; Lupato, A; Luppi, E; Lupton, O; Machefert, F; Machikhiliyan, I V; Maciuc, F; Maev, O; Malde, S; Malinin, A; Manca, G; Mancinelli, G; Mapelli, A; Maratas, J; Marchand, J F; Marconi, U; Marin Benito, C; Marino, P; Märki, R; Marks, J; Martellotti, G; Martens, A; Martín Sánchez, A; Martinelli, M; Martinez Santos, D; Martinez Vidal, F; Martins Tostes, D; Massafferri, A; Matev, R; Mathe, Z; Matteuzzi, C; Mazurov, A; McCann, M; McCarthy, J; McNab, A; McNulty, R; McSkelly, B; Meadows, B; Meier, F; Meissner, M; Merk, M; Milanes, D A; Minard, M-N; Moggi, N; Molina Rodriguez, J; Monteil, S; Morandin, M; Morawski, P; Mordà, A; Morello, M J; Moron, J; Morris, A-B; Mountain, R; Muheim, F; Müller, K; Mussini, M; Muster, B; Naik, P; Nakada, T; Nandakumar, R; Nasteva, I; Needham, M; Neri, N; Neubert, S; Neufeld, N; Neuner, M; Nguyen, A D; Nguyen, T D; Nguyen-Mau, C; Nicol, M; Niess, V; Niet, R; Nikitin, N; Nikodem, T; Novoselov, A; O'Hanlon, D P; Oblakowska-Mucha, A; Obraztsov, V; Oggero, S; Ogilvy, S; Okhrimenko, O; Oldeman, R; Onderwater, G; Orlandea, M; Otalora Goicochea, J M; Owen, P; Oyanguren, A; Pal, B K; Palano, A; Palombo, F; Palutan, M; Panman, J; Papanestis, A; Pappagallo, M; Pappalardo, L L; Parkes, C; Parkinson, C J; Passaleva, G; Patel, G D; Patel, M; Patrignani, C; Pazos Alvarez, A; Pearce, A; Pellegrino, A; Pepe Altarelli, M; Perazzini, S; Perez Trigo, E; Perret, P; Perrin-Terrin, M; Pescatore, L; Pesen, E; Petridis, K; Petrolini, A; Picatoste Olloqui, E; Pietrzyk, B; Pilař, T; Pinci, D; Pistone, A; Playfer, S; Plo Casasus, M; Polci, F; Poluektov, A; Polycarpo, E; Popov, A; Popov, D; Popovici, B; Potterat, C; Price, E; Prisciandaro, J; Pritchard, A; Prouve, C; Pugatch, V; Puig Navarro, A; Punzi, G; Qian, W; Rachwal, B; Rademacker, J H; Rakotomiaramanana, B; Rama, M; Rangel, M S; Raniuk, I; Rauschmayr, N; Raven, G; Reichert, S; Reid, M M; Dos Reis, A C; Ricciardi, S; Richards, S; Rihl, M; Rinnert, K; Rives Molina, V; Roa Romero, D A; Robbe, P; Rodrigues, A B; Rodrigues, E; Rodriguez Perez, P; Roiser, S; Romanovsky, V; Romero Vidal, A; Rotondo, M; Rouvinet, J; Ruf, T; Ruffini, F; Ruiz, H; Ruiz Valls, P; Saborido Silva, J J; Sagidova, N; Sail, P; Saitta, B; Salustino Guimaraes, V; Sanchez Mayordomo, C; Sanmartin Sedes, B; Santacesaria, R; Santamarina Rios, C; Santovetti, E; Sarti, A; Satriano, C; Satta, A; Saunders, D M; Savrie, M; Savrina, D; Schiller, M; Schindler, H; Schlupp, M; Schmelling, M; Schmidt, B; Schneider, O; Schopper, A; Schune, M-H; Schwemmer, R; Sciascia, B; Sciubba, A; Seco, M; Semennikov, A; Sepp, I; Serra, N; Serrano, J; Sestini, L; Seyfert, P; Shapkin, M; Shapoval, I; Shcheglov, Y; Shears, T; Shekhtman, L; Shevchenko, V; Shires, A; Silva Coutinho, R; Simi, G; Sirendi, M; Skidmore, N; Skwarnicki, T; Smith, N A; Smith, E; Smith, E; Smith, J; Smith, M; Snoek, H; Sokoloff, M D; Soler, F J P; Soomro, F; Souza, D; Souza De Paula, B; Spaan, B; Sparkes, A; Spradlin, P; Sridharan, S; Stagni, F; Stahl, M; Stahl, S; Steinkamp, O; Stenyakin, O; Stevenson, S; Stoica, S; Stone, S; Storaci, B; Stracka, S; Straticiuc, M; Straumann, U; Stroili, R; Subbiah, V K; Sun, L; Sutcliffe, W; Swientek, K; Swientek, S; Syropoulos, V; Szczekowski, M; Szczypka, P; Szilard, D; Szumlak, T; T'Jampens, S; Teklishyn, M; Tellarini, G; Teubert, F; Thomas, C; Thomas, E; van Tilburg, J; Tisserand, V; Tobin, M; Tolk, S; Tomassetti, L; Tonelli, D; Topp-Joergensen, S; Torr, N; Tournefier, E; Tourneur, S; Tran, M T; Tresch, M; Tsaregorodtsev, A; Tsopelas, P; Tuning, N; Ubeda Garcia, M; Ukleja, A; Ustyuzhanin, A; Uwer, U; Vagnoni, V; Valenti, G; Vallier, A; Vazquez Gomez, R; Vazquez Regueiro, P; Vázquez Sierra, C; Vecchi, S; Velthuis, J J; Veltri, M; Veneziano, G; Vesterinen, M; Viaud, B; Vieira, D; Vieites Diaz, M; Vilasis-Cardona, X; Vollhardt, A; Volyanskyy, D; Voong, D; Vorobyev, A; Vorobyev, V; Voß, C; Voss, H; de Vries, J A; Waldi, R; Wallace, C; Wallace, R; Walsh, J; Wandernoth, S; Wang, J; Ward, D R; Watson, N K; Websdale, D; Whitehead, M; Wicht, J; Wiedner, D; Wilkinson, G; Williams, M P; Williams, M; Wilson, F F; Wimberley, J; Wishahi, J; Wislicki, W; Witek, M; Wormser, G; Wotton, S A; Wright, S; Wu, S; Wyllie, K; Xie, Y; Xing, Z; Xu, Z; Yang, Z; Yuan, X; Yushchenko, O; Zangoli, M; Zavertyaev, M; Zhang, L; Zhang, W C; Zhang, Y; Zhelezov, A; Zhokhov, A; Zhong, L; Zvyagin, A

    2014-10-17

    The resonant substructure of B(s)(0) → D(0)K(-)π(+) decays is studied using a data sample corresponding to an integrated luminosity of 3.0 fb(-1) of pp collision data recorded by the LHCb detector. An excess at m(D(0)K(-))≈ 2.86 GeV/c(2) is found to be an admixture of spin-1 and spin-3 resonances. Therefore, the D(sJ)*(2860)(-) state previously observed in inclusive e(+)e(-) → D(0)K(-)X and pp → D(0)K(-)X processes consists of at least two particles. This is the first observation of a heavy flavored spin-3 resonance, and the first time that any spin-3 particle has been seen to be produced in B decays. The masses and widths of the new states and of the D(s2)*(2573)(-) meson are measured, giving the most precise determinations to date.

  11. Transient magnetization dynamics of spin-torque oscillator and magnetic dot coupled by magnetic dipolar interaction: Reading of magnetization direction using magnetic resonance

    Science.gov (United States)

    Kanao, Taro; Suto, Hirofumi; Kudo, Kiwamu; Nagasawa, Tazumi; Mizushima, Koichi; Sato, Rie

    2018-01-01

    We study the magnetization dynamics of a spin-torque oscillator (STO) and a magnetic dot coupled by a magnetic dipolar field using micromagnetic simulation with the aim of developing a read method in magnetic recording that uses magnetic resonance. We propose an STO with a perpendicularly magnetized free layer and an in-plane-magnetized fixed layer as a suitable STO for this resonance read method. When the oscillation frequency of the STO is near the ferromagnetic resonance (FMR) frequency of the magnetic dot, the oscillation amplitude of the STO decreases because FMR excited in the magnetic dot causes additional dissipation. To estimate the read rate of the resonance read method, we study the transient magnetization dynamics to the coupled oscillation state from an initial state where the STO is in a free-running state and the magnetic dot is in a stationary stable state. The STO shows transient dynamics within a time scale of 1 ns, which means that the STO can perform resonance reading with a response time within this time scale. This response time is shorter when the separation length between the STO and the magnetic dot is shorter, which indicates that the response speed can become faster by increasing the strength of the interaction between the STO and the magnetic dot. Successive reads are demonstrated by moving the STO over an array of magnetic dots.

  12. Electron Spin Resonance Shift and Linewidth Broadening of Nitrogen-Vacancy Centers in Diamond as a Function of Electron Irradiation Dose

    OpenAIRE

    Kim, Edwin; Acosta, Victor M.; Bauch, Erik; Budker, Dmitry; Hemmer, Philip R.

    2009-01-01

    A high-nitrogen-concentration diamond sample was subject to 200-keV electron irradiation using a transmission electron microscope. The optical and spin-resonance properties of the nitrogen-vacancy (NV) color centers were investigated as a function of the irradiation dose up to 6.4\\times1021 e-/cm2. The microwave transition frequency of the NV- center was found to shift by up to 0.6% (17.1 MHz) and the linewidth broadened with increasing electron-irradiation dose. Unexpectedly, the measured ma...

  13. Radio-frequency quadrupole resonator for linear accelerator

    Science.gov (United States)

    Moretti, A.

    1982-10-19

    An RFQ resonator for a linear accelerator having a reduced level of interfering modes and producing a quadrupole mode for focusing, bunching and accelerating beams of heavy charged particles, with the construction being characterized by four elongated resonating rods within a cylinder with the rods being alternately shorted and open electrically to the shell at common ends of the rods to provide an LC parallel resonant circuit when activated by a magnetic field transverse to the longitudinal axis.

  14. Dependence of the colored frequency noise in spin torque oscillators on current and magnetic field

    International Nuclear Information System (INIS)

    Eklund, Anders; Sani, Sohrab R.; Chung, Sunjae; Amir Hossein Banuazizi, S.; Östling, Mikael; Gunnar Malm, B.; Bonetti, Stefano; Majid Mohseni, S.; Persson, Johan; Iacocca, Ezio; Åkerman, Johan

    2014-01-01

    The nano-scale spin torque oscillator (STO) is a compelling device for on-chip, highly tunable microwave frequency signal generation. Currently, one of the most important challenges for the STO is to increase its longer-time frequency stability by decreasing the 1/f frequency noise, but its high level makes even its measurement impossible using the phase noise mode of spectrum analyzers. Here, we present a custom made time-domain measurement system with 150 MHz measurement bandwidth making possible the investigation of the variation of the 1/f as well as the white frequency noise in a STO over a large set of operating points covering 18–25 GHz. The 1/f level is found to be highly dependent on the oscillation amplitude-frequency non-linearity and the vicinity of unexcited oscillation modes. These findings elucidate the need for a quantitative theoretical treatment of the low-frequency, colored frequency noise in STOs. Based on the results, we suggest that the 1/f frequency noise possibly can be decreased by improving the microstructural quality of the metallic thin films

  15. Collective spin excitations in the singlet-correlated band model: a comparison with resonant inelastic x-ray scattering

    International Nuclear Information System (INIS)

    Eremin, M V; Shigapov, I M; Thuy, Ho Thi Duyen

    2013-01-01

    We analyse the spin excitations near the optimal doping of superconducting layered cuprates taking into account both the local and the itinerant spin components self-consistently. The obtained expression allows us to reproduce well the basic features of the resonant inelastic x-ray scattering and neutron scattering data experiments using a reasonable set of tight-binding parameters corresponding to the angle-resolved photoemission spectroscopy data. We also find that the spin excitation branch along the (0,0) − (0,π) symmetry direction in the first Brillouin zone shows a splitting at T c . Possible experiments for verification of that prediction are briefly discussed. (paper)

  16. Formulation of spin 7/2 and 9/2 nucleon resonance amplitudes for kaon photoproduction off a proton

    Energy Technology Data Exchange (ETDEWEB)

    Clymton, S., E-mail: samsonclymton@gmail.com; Mart, T. [Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia)

    2016-04-19

    We have constructed the formulation of scattering amplitude for kaon photoproduction off a proton that includes nucleon resonances with spins 7/2 and 9/2. To this end we start with the formalism of projection operator for higher spins and derive the spins 7/2 and 9/2 projection operators. The corresponding Feynman propagators are obtained from these projection operators. To calculate the scattering amplitude we use the vertex factor proposed by Pascalutsa. The scattering amplitudes are then decomposed into six Lorentz- and gauge-invariant amplitudes, from which the cross section and polarization observables can be calculated.

  17. Noninvasive measurements of regional cerebral perfusion in preterm and term neonates by magnetic resonance arterial spin labeling

    DEFF Research Database (Denmark)

    Miranda Gimenez-Ricco, Maria Jo; Olofsson, K; Sidaros, Karam

    2006-01-01

    Magnetic resonance arterial spin labeling (ASL) at 3 Tesla has been investigated as a quantitative technique for measuring regional cerebral perfusion (RCP) in newborn infants. RCP values were measured in 49 healthy neonates: 32 preterm infants born before 34 wk of gestation and 17 term-born neon......Magnetic resonance arterial spin labeling (ASL) at 3 Tesla has been investigated as a quantitative technique for measuring regional cerebral perfusion (RCP) in newborn infants. RCP values were measured in 49 healthy neonates: 32 preterm infants born before 34 wk of gestation and 17 term...

  18. Double-finger-gate controlled spin-resolved resonant quantum transport in the presence of a Rashba-Zeeman gap.

    Science.gov (United States)

    Tang, Chi-Shung; Tseng, Shu-Ting; Gudmundsson, Vidar; Cheng, Shun-Jen

    2015-03-04

    We investigate double finger gate (DFG) controlled spin-resolved resonant transport properties in an n-type quantum channel with a Rashba-Zeeman (RZ) subband energy gap. By appropriately tuning the DFG in the strong Rashba coupling regime, resonant state structures in conductance can be found that are sensitive to the length of the DFG system. Furthermore, a hole-like bound state feature below the RZ gap and an electron-like quasi-bound state feature at the threshold of the upper spin branch can be found that is insensitive to the length of the DFG system.

  19. Electron spin resonance studies of Bi1-xScxFeO3 nanoparticulates: Observation of an enhanced spin canting over a large temperature range

    Science.gov (United States)

    Titus, S.; Balakumar, S.; Sakar, M.; Das, J.; Srinivasu, V. V.

    2017-12-01

    Bi1-xScxFeO3 (x = 0.0, 0.1, 0.15, 0.25) nano particles were synthesized by sol gel method. We then probed the spin system in these nano particles using electron spin resonance technique. Our ESR results strongly suggest the scenario of modified spin canted structures. Spin canting parameter Δg/g as a function of temperature for Scandium doped BFO is qualitatively different from undoped BFO. A broad peak is observed for all the Scandium doped BFO samples and an enhanced spin canting over a large temperature range (75-210 K) in the case of x = 0.15 doping. We also showed that the asymmetry parameter and thereby the magneto-crystalline anisotropy in these BSFO nanoparticles show peaks around 230 K for (x = 0.10 and 0.15) and beyond 300 K for x = 0.25 system. Thus, we established that the Sc doping significantly modifies the spin canting and magneto crystalline anisotropy in the BFO system.

  20. New Method for Determining the Quality Factor and Resonance Frequency of Superconducting Micro-Resonators from Sonnet Simulations

    Science.gov (United States)

    Wisbey, D. S.; Martin, A.; Reinisch, A.; Gao, J.

    2014-08-01

    Lithographed superconducting microwave resonators (micro-resonators) are useful in a number of important applications, including microwave kinetic inductance detectors (Day et al., Nature 425:817, 2003), as memory elements in quantum information circuits, and as readouts of qubits and nanomechanical resonators. One of the major tasks in designing these devices is to find the resonance frequency (f) and quality factor (Q) for these microwave circuits using EM simulation software such as Sonnet. The traditional method iteratively runs simulations over successively smaller frequency ranges. In this way the simulated transmission S data is zoomed in on to yield a well-sampled resonance curve of a circuit. Designing microwave resonators in this manner is often time consuming since it requires many simulation runs. In this work, we show a new—and much faster—method for determining f and Q by adding an internal (virtual) port in the Sonnet model and examining the input impedance through the added port. Accurate f and Q values can be retrieved from a single simulation with a wide frequency sweep. This method works on many types of resonance circuits and dramatically reduces the simulation time.

  1. Identification and dosimetric features of γ-irradiated cefadroxil by electron spin resonance

    International Nuclear Information System (INIS)

    Aydas, Canan; Polat, Mustafa; Korkmaz, Mustafa

    2008-01-01

    In the present work, electron spin resonance (ESR) identification of γ-irradiated cefadroxil monohydrate (CM), duricef capsule (DC) and duricef suspension (DS) and their potential use as normal and/or accidental dosimetric materials were investigated in the dose range of 1-25 kGy. Although unirradiated samples did not exhibit any ESR signals, irradiated samples were observed to present ESR spectra with many resonance lines originating from radiation induced radical or radicals. Dose-response curves associated with the resonance peak heights of CM (I 1 , I 2 ) and DS (I 3 , I 4 , I 5 , I 6 ) were found to follow linear and power functions of applied radiation dose, respectively. Simulation calculations were performed to determine the structure and spectral parameters of the radiation-induced radicalic species involved in the formation of experimental ESR spectrum of CM using, as input, the room temperature signal intensity data obtained for a sample irradiated at dose of 10 kGy. Kinetic behaviors and activation energies of the radicalic species were also calculated using the data obtained from annealing studies performed at five different temperatures. The presence of detectable signal intensities even after a storage period of 100 days was considered as providing an opportunity in the discrimination of irradiated CM and DS from unirradiated ones. Basing on room temperature signal intensity decay and dose-response data, it was concluded that CM and DS present the features of a good dosimetric material

  2. Current-driven resonant excitation of magnetic vortex

    OpenAIRE

    Kasai, Shinya; Nakatani, Yoshinobu; Kobayashi, Kensuke; Kohno, Hiroshi; Ono, Teruo

    2006-01-01

    A magnetic vortex core in a ferromagnetic circular nanodot has a resonance frequency originating from the confinement of the vortex core. By the micromagnetic simulation including the spin-transfer torque, we show that the vortex core can be resonantly excited by an AC (spin-polarized) current through the dot and that the resonance frequency can be tuned by the dot shape. The resistance measurement under the AC current successfully detects the resonance at the frequency consistent with the si...

  3. Fast Electrical Control of Single Electron Spins in Quantum Dots with Vanishing Influence from Nuclear Spins

    Science.gov (United States)

    Yoneda, J.; Otsuka, T.; Nakajima, T.; Takakura, T.; Obata, T.; Pioro-Ladrière, M.; Lu, H.; Palmstrøm, C. J.; Gossard, A. C.; Tarucha, S.

    2014-12-01

    We demonstrate fast universal electrical spin manipulation with inhomogeneous magnetic fields. With fast Rabi frequency up to 127 MHz, we leave the conventional regime of strong nuclear-spin influence and observe a spin-flip fidelity >96 % , a distinct chevron Rabi pattern in the spectral-time domain, and a spin resonance linewidth limited by the Rabi frequency, not by the dephasing rate. In addition, we establish fast z rotations up to 54 MHz by directly controlling the spin phase. Our findings will significantly facilitate tomography and error correction with electron spins in quantum dots.

  4. Valley and spin resonant tunneling current in ferromagnetic/nonmagnetic/ferromagnetic silicene junction

    Directory of Open Access Journals (Sweden)

    Yaser Hajati

    2016-02-01

    Full Text Available We study the transport properties in a ferromagnetic/nonmagnetic/ferromagnetic (FNF silicene junction in which an electrostatic gate potential, U, is attached to the nonmagnetic region. We show that the electrostatic gate potential U is a useful probe to control the band structure, quasi-bound states in the nonmagnetic barrier as well as the transport properties of the FNF silicene junction. In particular, by introducing the electrostatic gate potential, both the spin and valley conductances of the junction show an oscillatory behavior. The amplitude and frequency of such oscillations can be controlled by U. As an important result, we found that by increasing U, the second characteristic of the Klein tunneling is satisfied as a result of the quasiparticles chirality which can penetrate through a potential barrier. Moreover, it is found that for special values of U, the junction shows a gap in the spin and valley-resolve conductance and the amplitude of this gap is only controlled by the on-site potential difference, Δz. Our findings of high controllability of the spin and valley transport in such a FNF silicene junction may improve the performance of nano-electronics and spintronics devices.

  5. Frequency Characteristics of Double-Walled Carbon Nanotube Resonator with Different Length

    Directory of Open Access Journals (Sweden)

    Jun-Ha LEE

    2016-05-01

    Full Text Available In this paper, we have conducted classical molecular dynamics simulations for DWCNTs of various wall lengths to investigate their use as ultrahigh frequency nano-mechanical resonators. We sought to determine the variations in the frequency of these resonators according to changes in the DWCNT wall lengths. For a double-walled carbon nanotube resonator with a shorter inner nanotube, the shorter inner nanotube can be considered to be a flexible core, and thus, the length influences the fundamental frequency. In this paper, we analyze the variation in frequency of ultra-high frequency nano-mechnical resonators constructed from DWCNTs with different wall lengths.DOI: http://dx.doi.org/10.5755/j01.ms.22.2.12951

  6. Resonant TMR inversion in LiF/EuS based spin-filter tunnel junctions

    Directory of Open Access Journals (Sweden)

    Fen Liu

    2016-08-01

    Full Text Available Resonant tunneling can lead to inverse tunnel magnetoresistance when impurity levels rather than direct tunneling dominate the transport process. We fabricated hybrid magnetic tunnel junctions of CoFe/LiF/EuS/Ti, with an epitaxial LiF energy barrier joined with a polycrystalline EuS spin-filter barrier. Due to the water solubility of LiF, the devices were fully packaged in situ. The devices showed sizeable positive TMR up to 16% at low bias voltages but clearly inverted TMR at higher bias voltages. The TMR inversion depends sensitively on the thickness of LiF, and the tendency of inversion disappears when LiF gets thick enough and recovers its intrinsic properties.

  7. ESR (electron spin resonance)-determined osmotic behavior of bull spermatozoa

    Energy Technology Data Exchange (ETDEWEB)

    Du, J.; Kleinhans, F.W.; Spitzer, V.J.; Critser, J.K. (Methodist Hospital, Indianapolis, IN (USA). Dept. of Medical Research); Horstman, L. (Purdue Univ., Lafayette, IN (USA). School of Veterinary Medicine); Mazur, P. (Oak Ridge National Lab., TN (USA))

    1990-01-01

    Our laboratories are pursuing a fundamental approach to the problems of semen cryopreservation. For many cell types (human red cells, yeast, HeLa) it has been demonstrated that there is an optimum cooling rate for cryopreservation. Faster rates allow insufficient time for cell dehydration and result in intracellular ice formation and cell death. It is possible to predict this optimal rate provided that the cell acts as an ideal osmometer and several other cell parameters are known such as the membrane hydraulic conductivity. It is the purpose of this work to examine the osmotic response of bull sperm to sucrose and NaCl utilizing electron spin resonance (ESR) to measure cell volume. For calibration purposes we also measured the ESR response of human red cells (RBC), the osmotic response of which is well documented with other methods. 15 refs., 1 fig.

  8. Spin Ensembles Coupled to Superconducting Resonators: A Scalable Architecture for Solid-State Quantum Computing

    International Nuclear Information System (INIS)

    Chen Chang-Yong; Li Shao-Hua; Hou Qi-Zhe

    2014-01-01

    A design is proposed for scalable solid-state quantum computing, which is based on collectively enhanced magnetic coupling between nitrogen-vacancy center ensembles and superconducting transmission line resonators interconnected by current-biased Josephson junction superconducting phase qubit. In this hybrid system, we realize distant multi-qubit controlled phase gate operations and generate distant multi-qubit entangled W-like states, being indispensable resource to quantum computation. Our proposed architecture consists of solid-state spin ensembles and circuit QED, and could achieve quantum computing in a solid-state environment with high-fidelity and scalable way. The experimental feasibility is discussed, and the implementation efficiency is demonstrated numerically. (general)

  9. Detection of irradiated deboned turkey meat using electron spin resonance spectroscopy

    Science.gov (United States)

    Gray, Richard; Stevenson, M. Hilary

    Bone fragments were extracted from two blocks of frozen deboned turkey meat (irradiated and non-irradiated) using alcoholic KOH digestion. Electron spin resonance (ESR) spectroscopy was used to differentiate between the samples. Comparison of an alcoholic KOH digestion procedure with a freeze drying and grinding method showed that the former method gave a signal which was 78% of that obtained using the freeze drying procedure. Regression analysis of the results obtained after subjection of the original non-irradiated sample to irradiation doses of 3.0, 5.0 and 7.0 kGy gave a linear relationship between irradiation dose and ESR signal strength over this range. Using this relationship the estimated mean dose received by the irradiated block was 4.72 kGy.

  10. Electron spin resonance dating of teeth from Western Brazilian megafauna - preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, Angela, E-mail: angela.kinoshita@usc.br [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto-SP (Brazil); Universidade Sagrado Coracao, Rua Irma Arminda 10-50, 17011-160 Bauru - Sao Paulo (Brazil); Jose, Flavio A. [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto-SP (Brazil); Sundaram, Dharani; Paixao, Jesus da S.; Soares, Isabella R.M. [Universidade Federal de Mato Grosso, Departamento de Geologia Geral, 78090-000 Cuiaba-MT (Brazil); Figueiredo, Ana Maria [Instituto de Pesquisas Energeticas e Nucleares (IPEN), 05422-970 Sao Paulo-SP (Brazil); Baffa, Oswaldo [Departamento de Fisica, FFCLRP, Universidade de Sao Paulo, 14040-901 Ribeirao Preto-SP (Brazil)

    2011-09-15

    Electron Spin Resonance (ESR) was applied to determine ages of Haplomastodon teeth from Western Brazilian Megafauna. The Equivalent Doses (D{sub e}) of (1.3 {+-} 0.2)kGy, (800 {+-} 100)Gy and (140 {+-} 20)Gy were found and the software ROSY ESR dating was employed to convert D{sub e} in age, using isotope concentrations determined by neutron activation analysis (NAA) and other information, resulting in (500 {+-} 100)ka, (320 {+-} 50) and (90 {+-} 10)ka considering the Combination Uptake (CU) model for Uranium uptake, set as an Early Uptake (EU) for dentine and Linear Uptake (LU) for enamel. There are scarce reports about Pleistocene Megafauna in this area. This paper presents the first dating of megafauna tooth and this study could contribute to improve the knowledge about the paleoclimate and paleoenvironment of this region and prompt more investigations in this area.

  11. Electron Spin Resonance and Atomic Force Microscopy Study on Gadolinium Doped Ceria

    Directory of Open Access Journals (Sweden)

    Cesare Oliva

    2015-01-01

    Full Text Available A combined electron spin resonance (ESR and atomic force microscopy (AFM study on Ce1−xGdxO2−x/2 samples is here presented, aimed at investigating the evolution of the ESR spectral shape as a function of x in a wide composition range. At low x=0.02, the spectrum is composed of features at geff≈2; 2.8; 6. With increasing x, this pattern merges into a single geff≈2 broad ESR curve, which assumes a Dysonian-shaped profile at x≥0.5, whereas, at these x values, AFM measurements show an increasing surface roughness. It is suggested that the last could cause the formation of surface polaritons at the origin of the particular ESR spectral profile observed at these high Gd doping levels.

  12. Detection of irradiated deboned turkey meat using electron spin resonance spectroscopy

    International Nuclear Information System (INIS)

    Gray, Richard; Stevenson, M.H.

    1989-01-01

    Bone fragments were extracted from two blocks of frozen deboned turkey meat (irradiated and non-irradiated) using alcoholic KOH digestion. Electron spin resonance (ESR) spectroscopy was used to differentiate between the samples. Comparison of an alcoholic KOH digestion procedure with a freeze drying and grinding method showed that the former method gave a signal which was 78% of that obtained using the freeze drying procedure. Regression analysis of the results obtained after subjection of the original non-irradiated sample to irradiation doses of 3.0, 5.0 and 7.0 kGy gave a linear relationship between irradiation dose and ESR signal strength over this range. Using this relationship the estimated mean dose received by the irradiated block was 4.72 kGy. (author)

  13. Electron Spin Resonance Dating of Some Animal Teeth Enamel and Shell Fossils

    International Nuclear Information System (INIS)

    Athabutra, Supakij; Siri-Upathum, Chyagrit

    2007-08-01

    Full text: Electron spin resonance (ESR) dating was conducted for some ungulate tooth enamel samples and shell fossils of the the Tham Lod rock shelter Area I (S23W10) located in Highland Archaeology Project in Pang Mapha District, Mae Hong Son Province, Thailand. Age estimation for wave-induced breaching of the cavity and initial sand deposition (Level 19-29) was 33,200 - 18,700 years and 32,300 years for teeth enamel and the shell fossils of Nodularia scobinata sp. (Carditidae) respectively. ESR spectra showed g-factor g1 (gll, gcenter) = 2.0030 - 2.0036, g2 = 2.0040 - 2.0041 and g3 (g?) = 1.997 - 1.9988 formed by CO2- orthorhombic free radical for teeth enamel and g-factor (gcenter) = 2.0042 + 0.0003 formed by SO3- free radical for fresh shell fossils

  14. Resonance frequency of microbubbles in small blood vessels: a numerical study

    International Nuclear Information System (INIS)

    Sassaroli, E; Hynynen, K

    2005-01-01

    Microbubbles are currently used as ultrasound contrast agents. Their potential therapeutic applications are also under investigation. This work is designed to provide some insight into the mechanisms of energy absorption and deposition by a preformed gas bubble in the microvasculature to optimize its efficacy. In the linear regime, the most favourable condition for the transfer of energy from an ultrasonic field to a gas bubble occurs when the centre frequency of the ultrasonic field equals the resonance frequency of the bubble. The resonance frequency of gas microbubbles has been investigated up to now mainly in unbounded liquids; however when bubbles are confined in small regions, their resonance frequency is strongly affected by the surrounding boundaries. A parametric study on how the resonance frequency of microbubbles in blood vessels is affected by the bubble radius, vessel radius and the bubble position in the vessel is presented. The resonance frequency decreases below its free value with decreasing vessel radius for vessels smaller than 200-300 μm depending on the bubble size. This model suggests the possibility of using ultrasound in a range of frequencies that are, in general, lower than the ones used now for therapeutic and diagnostic applications of ultrasound (a few MHz). When microbubbles oscillate at their resonance frequency they absorb and therefore emit more energy. This energy may allow specific blood vessels to be targeted for both diagnostic and therapeutic applications of ultrasound

  15. Frequency of common bile duct motion artifacts caused by inferior vena cava pulsation on magnetic resonance cholangiopancreatography

    International Nuclear Information System (INIS)

    Morita, Satoru; Ueno, Eiko; Saito, Naoko

    2008-01-01

    We assessed the frequency of common bile duct (CBD) motion artifacts caused by inferior vena cava (IVC) pulsation on magnetic resonance cholangiopancreatography (MRCP). We retrospectively evaluated CBD motion artifacts in 4 MRCP sequences from each of 115 consecutive patients. We observed 37 (32.2%) ghost artifacts at the ventral and dorsal aspects of the CBD on transaxial, half-Fourier acquisition single-shot turbo spin-echo (HASTE-ax) images; no such artifacts were observed on transaxial T 2 -weighted turbo spin-echo images. In 10 patients, we observed 9 (7.8%) pseudo-defects of the CBD on 3-dimensional T 2 -weighted turbo spin-echo with navigator-triggered prospective acquisition correction technique MRCP and 6 (5.2%) pseudo-defects on single-shot rapid acquisition with relaxation enhancement MRCP. Pseudo-defects were significantly more frequent in patients with ghost artifacts than without (9 of 37 [24.3%] versus one of 78 [1.3%]; P<0.01, McNemar test). Although uncommon, pseudo-defects of the CBD caused by IVC pulsation are observed on MRCP. MRCP interpretation that includes comparison with HASTE-ax images can diminish the potential misinterpretation of such CBD motion artifact as bile duct tumor or biliary stone. (author)

  16. Electron Spin Resonance Experiments on a Single Electron in Silicon Implanted with Phosphorous

    Science.gov (United States)

    Luhman, Dwight R.; Nguyen, K.; Tracy, L. A.; Carr, S.; Borchardt, J.; Bishop, N.; Ten Eyck, G.; Pluym, T.; Wendt, J.; Lilly, M. P.; Carroll, M. S.

    2015-03-01

    In this talk we will discuss the results of our ongoing experiments involving electron spin resonance (ESR) on a single electron in a natural silicon sample. The sample consists of an SET, defined by lithographic polysilicon gates, coupled to nearby phosphorous donors. The SET is used to detect charge transitions and readout the spin of the electron being investigated with ESR. The measurements were done with the sample at dilution refrigerator temperatures in the presence of a 1.3 T magnetic field. We will present data demonstrating Rabi oscillations of a single electron in this system as well as measurements of the coherence time, T2. We will also discuss our results using these and various other pulsing schemes in the context of a donor-SET system. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE Office of Basic Energy Sciences user facility. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

  17. Resonant optical tunneling-induced enhancement of the photonic spin Hall effect

    Science.gov (United States)

    Jiang, Xing; Wang, Qingkai; Guo, Jun; Zhang, Jin; Chen, Shuqing; Dai, Xiaoyu; Xiang, Yuanjiang

    2018-04-01

    Due to the quantum analogy with optics, the resonant optical tunneling effect (ROTE) has been proposed to investigate both the fundamental physics and the practical applications of optical switches and liquid refractive index sensors. In this paper, the ROTE is used to enhance the spin Hall effect (SHE) of transmitted light. It is demonstrated that sandwiching a layer of a high-refractive-index medium (boron nitride crystal) between two low-refractive-index layers (silica) can effectively enhance the photonic SHE due to the increased refractive index gradient and an enhanced evanescent field near the interface between silica and boron nitride. A maximum transverse shift of the horizontal polarization state in the ROTE structure of about 22.25 µm has been obtained, which is at least three orders of magnitude greater than the transverse shift in the frustrated total internal reflection structure. Moreover, the SHE can be manipulated by controlling the component materials and the thickness of the ROTE structure. These findings open the possibility for future applications of photonic SHE in precision metrology and spin-based photonics.

  18. Mechanical design of RFQ resonator cavities in the 400-MHz frequency range

    International Nuclear Information System (INIS)

    Hansborough, L.D.; Potter, J.M.; Wilson, N.G.

    1981-01-01

    Many RFQ resonator-cavity design concepts have been proposed in the 400-MHz frequency range. Los Alamos has been evaluating RFQ resonator-cavity designs that provide acceptable combinations of necessary mechanical features, easy tunability and long-term stability. Four RFQ resonator test cavities have been fabricated to test rf joints between the RFQ vanes and the resonator cavity. Two of these joints (the C-seal and the rf clamp-joint) allow vane movement for tuning. These test data, and the design of the present generation of RFQ resonator cavities, are presented

  19. On the frequency and field linewidth conversion of ferromagnetic resonance spectra

    International Nuclear Information System (INIS)

    Wei, Yajun; Svedlindh, Peter; Liang Chin, Shin

    2015-01-01

    Both frequency swept and field swept ferromagnetic resonance measurements have been carried out for a number of different samples with negligible, moderate and significant extrinsic frequency independent linewidth contribution to analyze the correlation between the experimentally measured frequency and field linewidths. Contrary to the belief commonly held by many researchers, it is found that the frequency and field linewidth conversion relation does not hold for all cases. Instead it holds only for samples with negligible frequency independent linewidth contributions. For samples with non-negligible frequency independent linewidth contribution, the field linewidth values converted from the measured frequency linewidth are larger than the experimentally measured field linewidth. A close examination of the literature reveals that previously reported results support our findings, with successful conversions related to samples with negligible frequency independent linewidth contributions and unsuccessful conversions related to samples with significant frequency independent linewidth. The findings are important in providing guidance in ferromagnetic resonance linewidth conversions. (paper)

  20. Spatial profiling of degradation processes in hindered-amine-stabilized polymers by electron spin resonance imaging of nitroxides

    Czech Academy of Sciences Publication Activity Database

    Marek, Antonín; Kaprálková, Ludmila; Pfleger, Jiří; Pospíšil, Jan; Pilař, Jan

    2005-01-01

    Roč. 99, S (2005), s. 195-198 ISSN 0009-2770. [Meeting on Chemistry and Life /3./. Brno, 20.9.2005-22.9.2005] Institutional research plan: CEZ:AV0Z40500505 Keywords : polymer degradation * nitroxides * electron spin resonance imaging Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.445, year: 2005

  1. Identification of Copper(II) Complexes in Aqueous Solution by Electron Spin Resonance: An Undergraduate Coordination Chemistry Experiment.

    Science.gov (United States)

    Micera, G.; And Others

    1984-01-01

    Background, procedures, and results are provided for an experiment which examines, through electron spin resonance spectroscopy, complex species formed by cupric and 2,6-dihydroxybenzoate ions in aqueous solutions. The experiment is illustrative of several aspects of inorganic and coordination chemistry, including the identification of species…

  2. Ferromagnetic resonance study of the half-Heusler alloy NiMnSb. The benefit of using NiMnSb as a ferromagnetic layer in pseudo-spin-valve based spin-torque oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Riegler, Andreas

    2011-11-25

    Since the discovery of spin torque in 1996, independently by Berger and Slonczewski, and given its potential impact on information storage and communication technologies, (e.g. through the possibility of switching the magnetic configuration of a bit by current instead of a magnetic field, or the realization of high frequency spin torque oscillators (STO)), this effect has been an important field of spintronics research. One aspect of this research focuses on ferromagnets with low damping. The lower the damping in a ferromagnet, the lower the critical current that is needed to induce switching of a spin valve or induce precession of its magnetization. In this thesis ferromagnetic resonance (FMR) studies of NiMnSb layers are presented along with experimental studies on various spin-torque (ST) devices using NiMnSb. NiMnSb, when crystallized in the half-Heusler structure, is a half-metal which is predicted to have 100% spin polarization, a consideration which further increases its potential as a candidate for memory devices based on the giant magnetoresistance (GMR) effect. The FMR measurements show an outstandingly low damping factor for NiMnSb, in low 10{sup -3} range. This is about a factor of two lower than permalloy and well comparable to lowest damping for iron grown by molecular beam epitaxy (MBE). According to theory the 100% spin polarization properties of the bulk disappear at interfaces where the break in translational symmetry causes the gap in the minority spin band to collapse but can remain in other crystal symmetries such as (111). Consequently NiMnSb layers on (111)(In,Ga)As buffer are characterized in respect of anisotropies and damping. The FMR measurements on these samples indicates a higher damping that for the 001 samples, and a thickness dependent uniaxial in-plane anisotropy. Investigations of the material for device use is pursued by considering sub-micrometer sized elements of NiMnSb on 001 substrates, which were fabricated by electron

  3. New Method for Determining the Quality Factor and Resonance Frequency of Superconducting Micro-resonators from Sonnet Simulation

    Science.gov (United States)

    Wisbey, David; Reinisch, Alexander; Gardner, Wesley; Brewster, Jacob; Gao, Jiansong

    2013-03-01

    Lithographed superconducting microwave resonators (micro-resonators) are useful in a number of important applications including microwave kinetic inductance detectors (MKIDs), as a memory element in quantum information, and readout of qubits and nanomechanical resonators. One of the major tasks in designing these devices is to find the resonance frequency (fr) and quality factor (Q) for these microwave circuits using EM simulation software such as Sonnet. The traditional method iteratively sweeps and zooms in frequency to fit simulated S21 data, which is often time consuming. In this work, we show a new-and much faster-method for determining fr\\ and Q by adding an internal (virtual) port in the Sonnet model and examining the input impedance through the added port. Accurate fr and Q values can be retrieved from a single simulation with a wide frequency sweep. This is a robust method that works on many types of resonance circuits and eclipses the speed with which Q is traditionally extracted by eliminating the need for multiple frequency sweeps using Sonnet.

  4. External Ear Resonant Amplitude and Frequency of 3-7 Year Old Children

    Directory of Open Access Journals (Sweden)

    Amir Hossein Zare

    2004-06-01

    Full Text Available Objective: To measure external ear resonant amplitude and frequency in children (3-7 years old and to compare with adult measures. Method and materials: The external ear resonance peak amplitude and frequency of 63 children 3-7 years old were recorded. All of the children had normal tympanogram and there was no cerumen in external auditory canal. 20 adult of 21-24 years old (10 male , 10 female were selected in order to compare with children that had normal tympanogram. The tests included : 1-otoscopy 2- tympanometry 3-microphone probe tube test. Results: The average of resonance peak frequency for children and adult is 4200 Hz and 3200 Hz , respectively. The resonance frequency of children had significantly diffrence with average of resonance frequency in adults. The average of resonance peak amplitude for children and adult is 17.70 dB and 17.17 dB , respectively. Conclusion: Resonant frequency and amplitude affect the hearing aid prescription and fitting process and calculating insertion gain; so, this measures seem should be considered in children hearing aid fitting.

  5. Higher-order Zeeman and spin terms in the electron paramagnetic resonance spin Hamiltonian; their description in irreducible form using Cartesian, tesseral spherical tensor and Stevens' operator expressions

    International Nuclear Information System (INIS)

    McGavin, Dennis G; Tennant, W Craighead

    2009-01-01

    In setting up a spin Hamiltonian (SH) to study high-spin Zeeman and high-spin nuclear and/or electronic interactions in electron paramagnetic resonance (EPR) experiments, it is argued that a maximally reduced SH (MRSH) framed in tesseral combinations of spherical tensor operators is necessary. Then, the SH contains only those terms that are necessary and sufficient to describe the particular spin system. The paper proceeds then to obtain interrelationships between the parameters of the MRSH and those of alternative SHs expressed in Cartesian tensor and Stevens operator-equivalent forms. The examples taken, initially, are those of Cartesian and Stevens' expressions for high-spin Zeeman terms of dimension BS 3 and BS 5 . Starting from the well-known decomposition of the general Cartesian tensor of second rank to three irreducible tensors of ranks 0, 1 and 2, the decomposition of Cartesian tensors of ranks 4 and 6 are treated similarly. Next, following a generalization of the tesseral spherical tensor equations, the interrelationships amongst the parameters of the three kinds of expressions, as derived from equivalent SHs, are determined and detailed tables, including all redundancy equations, set out. In each of these cases the lowest symmetry, 1-bar Laue class, is assumed and then examples of relationships for specific higher symmetries derived therefrom. The validity of a spin Hamiltonian containing mixtures of terms from the three expressions is considered in some detail for several specific symmetries, including again the lowest symmetry. Finally, we address the application of some of the relationships derived here to seldom-observed low-symmetry effects in EPR spectra, when high-spin electronic and nuclear interactions are present.

  6. Multi-frequency and high-field EPR study of manganese(III) protoporphyrin IX reconstituted myoglobin with an S=2 integer electron spin.

    Science.gov (United States)

    Horitani, Masaki; Yashiro, Haruhiko; Hagiwara, Masayuki; Hori, Hiroshi

    2008-04-01

    We investigate the electronic state of Mn(III) center with an integer electron spin S=2 in the manganese(III) protoporphyrin IX reconstituted myoglobin, Mn(III)Mb, by means of multi-frequency electron paramagnetic resonance (MFEPR) spectroscopy. Using a bimodal cavity resonator, X-band EPR signal from Mn(III) center in the Mn(III)Mb was observed near zero-field region. The temperature dependence of this signal indicates a negative axial zero-field splitting value, DEPR analysis shows that this signal is attributed to the transition between the closely spaced M(s)=+/-2 energy levels for the z-axis, corresponding to the heme normal. To determine the zero-field splitting (ZFS) parameters, EPR experiments on the Mn(III)Mb were performed at various temperatures for some frequencies between 30GHz and 130GHz and magnetic fields up to 14T. We observed several EPR spectra which are analyzed with a spin Hamiltonian for S=2, yielding highly accurate ZFS parameters; D=-3.79cm(-1) and |E|=0.08cm(-1) for an isotropic g=2.0. These ZFS parameters are compared with those in some Mn(III) complexes and Mn(III) superoxide dismutase (SOD), and effects on these parameters by the coordination and the symmetry of the ligands are discussed. To the best of our knowledge, these EPR spectra in the Mn(III)Mb are the very first MFEPR spectra at frequencies higher than Q-band in a metalloprotein with an integer spin.

  7. [Frequency-domain quantification based on the singular value decomposition and frequency-selection for magnetic resonance spectra].

    Science.gov (United States)

    Men, Kuo; Quan, Hong; Yang, Peipei; Cao, Ting; Li, Weihao

    2010-04-01

    The frequency-domain magnetic resonance spectroscopy (MRS) is achieved by the Fast Fourier Transform (FFT) of the time-domain signals. Usually we are only interested in the portion lying in a frequency band of the whole spectrum. A method based on the singular value decomposition (SVD) and frequency-selection is presented in this article. The method quantifies the spectrum lying in the interested frequency band and reduces the interference of the parts lying out of the band in a computationally efficient way. Comparative experiments with the standard time-domain SVD method indicate that the method introduced in this article is accurate and timesaving in practical situations.

  8. Spectroscopy study of electron spin resonance of coal oxidation of different rank

    International Nuclear Information System (INIS)

    Enciso Prieto, Hector Manuel

    1992-01-01

    The present work constitutes an initial step for the knowledge of the coal oxidation, with the purpose of preventing the adverse influences caused by this phenomenon in the physical-chemical characteristics and in the tendency to the spontaneous combustion. Since the knowledge the influence of the free radicals in this process, their relative concentration was measured by means of the use of the technique of resonance spin electron. This technique measures the absorption of electromagnetic radiation, generally in the microwaves region, for the materials that not have electrons matched up in a strong magnetic field. In the essays of oxidation three coal of different range and different characteristics of mass were used and it was studied the influence of the temperature, particle size and the range. The results showed that the coal of Guacheta (bituminous low in volatile) it presents bigger concentration of free radicals, after the reaction with the atmospheric oxygen, with regard to the coal of the Cerrejon (bituminous high in volatile B) and Amaga (bituminous high in volatile C). Although this doesn't indicate that the coal of Guacheta is that more easily is oxidized, but rather it possibly presents stabilization of radicals for resonance. It concluded that there are differences in the oxidation mechanism between coal of different rank and different agglomeration properties

  9. Quaternary dating by electron spin resonance (ESR applied to human tooth enamel

    Directory of Open Access Journals (Sweden)

    Carvajal Eduar

    2011-12-01

    Full Text Available This paper presents the results obtained from using electron paramagnetic resonance (EPR to analyse tooth enamel found at the Aguazuque archaeological site (Cundinamarca, Colombia, located on the savannah near Bogota at 4° 37' North and 74°17' West. It was presumed that the tooth enamel came from a collective burial consisting of 23 people, involving men, women and children. The tooth enamel was irradiated with gamma rays and the resulting free radicals were measured using an electron spin resonance (ESR X-band spectrometer to obtain a signal intensity compared to absorbed doses curve. Fitting this curve allowed the mean archaeological dose accumulated in the enamel during the period that it was buried to be estimated, giving a 2.10 ± 0.14 Gyvalue. ROSY software was used for estimating age, giving a mean 3,256 ± 190y before present (BP age. These results highlight EPR's potential when using the quaternary ancient ruins dating technique in Colombia and its use with other kinds of samples like stalagmites, calcite, mollusc shells and reefs.

  10. High-Frequency Microstrip Cross Resonators for Circular Polarization EPR Spectroscopy

    OpenAIRE

    Henderson, J. J.; Ramsey, C. M.; Quddusi, H. M.; del Barco, E.

    2008-01-01

    In this article we discuss the design and implementation of a novel microstrip resonator which allows for the absolute control of the microwaves polarization degree for frequencies up to 30 GHz. The sensor is composed of two half-wavelength microstrip line resonators, designed to match the 50 Ohms impedance of the lines on a high dielectric constant GaAs substrate. The line resonators cross each other perpendicularly through their centers, forming a cross. Microstrip feed lines are coupled th...

  11. Time-frequency analysis of the restricted three-body problem: transport and resonance transitions

    International Nuclear Information System (INIS)

    Vela-Arevalo, Luz V; Marsden, Jerrold E

    2004-01-01

    A method of time-frequency analysis based on wavelets is applied to the problem of transport between different regions of the solar system, using the model of the circular restricted three-body problem in both the planar and the spatial versions of the problem. The method is based on the extraction of instantaneous frequencies from the wavelet transform of numerical solutions. Time-varying frequencies provide a good diagnostic tool to discern chaotic trajectories from regular ones, and we can identify resonance islands that greatly affect the dynamics. Good accuracy in the calculation of time-varying frequencies allows us to determine resonance trappings of chaotic trajectories and resonance transitions. We show the relation between resonance transitions and transport in different regions of the phase space

  12. GaN-based High Power High Frequency Wide Range LLC Resonant Converter, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — SET Group will design, build and demonstrate a Gallium Nitride (GaN) based High Power High Frequency Wide Range LLC Resonant Converter capable of handling high power...

  13. Single-Chip Multiple-Frequency RF MEMS Resonant Platform for Wireless Communications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A novel, single-chip, multiple-frequency platform for RF/IF filtering and clock reference based on contour-mode aluminum nitride (AlN) MEMS piezoelectric resonators...

  14. Single-Chip Multiple-Frequency RF MEMS Resonant Platform for Wireless Communications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A novel, single-chip, multiple-frequency platform for RF/IF filtering and clock reference based on contour-mode aluminum nitride (AlN) MEMS piezoelectric resonators...

  15. Very High Frequency Resonant DC/DC Converters for LED Lighting

    DEFF Research Database (Denmark)

    Madsen, Mickey Pierre; Knott, Arnold; Andersen, Michael A. E.

    2013-01-01

    This paper presents a very high frequency DC/DC converter for LED lighting. Several resonant topologies are compared and their usability discussed. At the end the resonant SEPIC converter is chosen based on the achievable power density and total bill of material. Simulations of a 51 MHz converter...

  16. Effect of metal coating and residual stress on the resonant frequency ...

    Indian Academy of Sciences (India)

    Effect of metal coating and residual stress on the resonant frequency of MEMS resonators. ASHOK KUMAR PANDEY, K P VENKATESH and RUDRA. PRATAP. ∗. CranesSci MEMS Laboratory, Department of Mechanical Engineering, Indian. Institute of Science, Bangalore 560 012 e-mail: pratap@mecheng.iisc.ernet.in.

  17. Use of a radio-frequency resonance circuit in studies of alkali ionization in flames

    International Nuclear Information System (INIS)

    Borgers, A.J.

    1978-01-01

    The construction of a radio-frequency resonance system and its use in the study of alkali metal ionization in flames is described. The author re-determines the values of the alkali ionization rate constants for a CO flame with N 2 as diluent gas of known temperature using the RF resonance method. (Auth.)

  18. Ion–Cyclotron Resonance Frequency Interval Dependence on the O ...

    Indian Academy of Sciences (India)

    observational data obtained from SOHO which suggests the ion–cyclotron resonance. (Marsch & Tu 1997; Doyle et al. 1999; Cranmer et al. 1999). In the kinetic model, Vlasov equation governs the time evolution of the distri- bution function of the plasma as a result of the energy transfer from ion–cyclotron waves to particles.

  19. Low frequency torsional vibration gaps in the shaft with locally resonant structures

    International Nuclear Information System (INIS)

    Yu Dianlong; Liu Yaozong; Wang Gang; Cai Li; Qiu Jing

    2006-01-01

    The propagation of torsional wave in the shaft with periodically attached local resonators is studied with the transfer matrix theory and the finite element method. The analytical dispersion relation and the complex band structure of such a structure is presented for the first time, which indicates the existence of low frequency gaps. The effect of shaft material on the vibration attenuation in band gap is investigated. The frequency response function of the shaft with finite periodic locally resonant oscillators is simulated with finite element method, which shows large vibration attenuation in the frequency range of the gap as expected. The low frequency torsional gap in shafts provides a new idea for vibration control

  20. Implementation of wireless battery-free microgyrosensor by utilizing one-port SAW delay line and an antenna with double resonant frequencies

    Science.gov (United States)

    Fu, C.; Elmarzia, O.; Lee, K.

    2014-03-01

    A wireless, battery-free gyroscope was developed by employing a one-port surface acoustic wave (SAW) reflective delay line, a SAW resonator, and an antenna. Two SAW devices with different center frequencies were simultaneously activated by one antenna with double resonant frequencies. During wireless testing, the developed gyroscope showed clear reflection peaks with high S/N ratios in both the time and frequency domains. Upon rotation of the device, large shifts of the reflection peaks were observed owing to a secondary wave interference effect caused by the Coriolis force that depends on the spinning rate. The measured sensitivity and linearity of the developed gyroscope were, respectively, 1.35 deg/(deg/s) and 0.91, which are promising values for our targeted applications. The temperature and vibration/shock effects were also characterized

  1. Resonances in BSO with frequency shifted input beams

    DEFF Research Database (Denmark)

    Buchhave, Preben; Vasnetsov, M.; Lyuksyutov, S.

    1996-01-01

    In this publication we report experiments with a frequency modulated offset frequency, which illustrate in which situations the problem may be considered linear, and in which it may not. Surprisingly we find, that even in the region of subharmonic generation, the space-charge field of the primary...

  2. Identification and dosimetric features of {gamma}-irradiated cefadroxil by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Aydas, Canan [Turkish Atomic Energy Authority, Saraykoey Nuclear Research and Training Centre, Ankara (Turkey); Polat, Mustafa [Physics Engineering Department, Hacettepe University, Beytepe, 06800 Ankara (Turkey)], E-mail: polat@hacettepe.edu.tr; Korkmaz, Mustafa [Physics Engineering Department, Hacettepe University, Beytepe, 06800 Ankara (Turkey)

    2008-01-15

    In the present work, electron spin resonance (ESR) identification of {gamma}-irradiated cefadroxil monohydrate (CM), duricef capsule (DC) and duricef suspension (DS) and their potential use as normal and/or accidental dosimetric materials were investigated in the dose range of 1-25 kGy. Although unirradiated samples did not exhibit any ESR signals, irradiated samples were observed to present ESR spectra with many resonance lines originating from radiation induced radical or radicals. Dose-response curves associated with the resonance peak heights of CM (I{sub 1}, I{sub 2}) and DS (I{sub 3}, I{sub 4}, I{sub 5}, I{sub 6}) were found to follow linear and power functions of applied radiation dose, respectively. Simulation calculations were performed to determine the structure and spectral parameters of the radiation-induced radicalic species involved in the formation of experimental ESR spectrum of CM using, as input, the room temperature signal intensity data obtained for a sample irradiated at dose of 10 kGy. Kinetic behaviors and activation energies of the radicalic species were also calculated using the data obtained from annealing studies performed at five different temperatures. The presence of detectable signal intensities even after a storage period of 100 days was considered as providing an opportunity in the discrimination of irradiated CM and DS from unirradiated ones. Basing on room temperature signal intensity decay and dose-response data, it was concluded that CM and DS present the features of a good dosimetric material.

  3. Modulation bandwidth of a spin laser

    Science.gov (United States)

    Banerjee, D.; Adari, R.; Murthy, M.; Suggisetti, P.; Ganguly, S.; Saha, D.

    2011-04-01

    We have studied small signal frequency response of a spin laser. We have shown that the response is characterized by two distinct resonant peaks corresponding to the two polarization modes of the spin laser. It is observed that the modulation bandwidth of a spin laser can be smaller or larger than that of a conventional laser depending upon the current bias and spin relaxation time constant. A small value for spin relaxation constant may not be detrimental for modulation bandwidth. This anomalous observation is explained by considering both the amplitude and phase response of the two polarization modes. A spin laser can act as a combination of low-pass and bandpass filters. The passband frequency range is tunable by external bias. We have also studied the evolution of resonant peaks and modulation bandwidth as a function of spin relaxation time constant.

  4. High Speed Laser with 100 Ghz Resonance Frequency

    Science.gov (United States)

    2014-02-28

    34Frequency Response Enhancement of Optical Injection-Locked Lasers," Quantum Electron. IEEE ]. Of, vol. 44, no. 1, pp. 90-99, 2008. [6] E. K. Lau, L . J...N l +-_^-sin(-9?0) where a is the linewidth enhancement parameter, Qat is the total cavity-Q [from mirror and internal loss], g is the...I! ■£ Q 20 40 60 80 100110 Modulation Frequency [GHz] (a) 1545 1546 1547 Wavelength [nm] (b) 20 40 60 80 100110 Modulation Frequency [GHz

  5. Study on frequency characteristics of wireless power transmission system based on magnetic coupling resonance

    Science.gov (United States)

    Liang, L. H.; Liu, Z. Z.; Hou, Y. J.; Zeng, H.; Yue, Z. K.; Cui, S.

    2017-11-01

    In order to study the frequency characteristics of the wireless energy transmission system based on the magnetic coupling resonance, a circuit model based on the magnetic coupling resonant wireless energy transmission system is established. The influence of the load on the frequency characteristics of the wireless power transmission system is analysed. The circuit coupling theory is used to derive the minimum load required to suppress frequency splitting. Simulation and experimental results verify that when the load size is lower than a certain value, the system will appear frequency splitting, increasing the load size can effectively suppress the frequency splitting phenomenon. The power regulation scheme of the wireless charging system based on magnetic coupling resonance is given. This study provides a theoretical basis for load selection and power regulation of wireless power transmission systems.

  6. Reduction process of nitroxyl spin probes used in Overhauser-enhanced magnetic resonance imaging: An ESR study

    Energy Technology Data Exchange (ETDEWEB)

    Meenakumari, V.; Premkumar, S.; Benial, A. Milton Franklin, E-mail: miltonfranklin@yahoo.com [Department of Physics, NMSSVN College, Nagamalai, Madurai-625 019, Tamilnadu (India); Jawahar, A. [Department of Chemistry, NMSSVN College, Nagamalai, Madurai-625 019, Tamilnadu (India)

    2016-05-23

    The Electron spin resonance studies on the reduction process of nitroxyl spin probes were carried out for 1mM {sup 14}N- labeled nitroxyl radicals in pure water and 1 mM concentration of ascorbic acid as a function of time. The electron spin resonance parameters, such as line width, hyperfine coupling constant, g-factor, signal intensity ratio and rotational correlation time were estimated. The 3-carbamoyl-PROXYL radical has narrowest line width and fast tumbling motion compared with 3-carboxy-PROXYL, 4-methoxy-TEMPO, and 4-acetamido-TEMPO radicals. The half life time and decay rate were estimated for 1mM concentration of {sup 14}N- labeled nitroxyl radicals in 1 mM concentration of ascorbic acid. From the results, the 3-carbamoyl-PROXYL has long half life time and high stability compared with 3-carboxy-PROXYL, 4-methoxy-TEMPO and 4-acetamido-TEMPO radicals. Therefore, this study reveals that the 3-carbamoyl-PROXYL radical can act as a good redox sensitive spin probe for Overhauser-enhanced Magnetic Resonance Imaging.

  7. Investigation of natural frequencies of laser inertial confinement fusion capsules using resonant ultrasound spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xiaojun [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Tang, Xing; Wang, Zongwei [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Chen, Qian; Qian, Menglu [Institute of Acoustic, Tongji University, Shanghai 200433 (China); Meng, Jie [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Tang, Yongjian [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Zou, Yaming; Shen, Hao [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Gao, Dangzhong, E-mail: dgaocn@163.com [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China)

    2017-01-15

    Highlights: • The frequency equation of isotropic multi-layer hollow spheres was derived using three-dimension (3D) elasticity theory and transfer matrix method. • The natural frequencies of the capsules with a millimeter-sized diameter are determined experimentally using resonant ultrasound spectrum (RUS) system. • The predicted natural frequencies of the frequency equation accord well with the observed results. • The theoretical and experimental investigation has proved the potential applicability of RUS to both metallic and non-metallic capsules. - Abstract: The natural frequency problem of laser inertial confinement fusion (ICF) capsules is one of the basic problems for determining non-destructively the elasticity modulus of each layer material using resonant ultrasound spectroscopy (RUS). In this paper, the frequency equation of isotropic one-layer hollow spheres was derived using three dimension (3D) elasticity theory and some simplified frequency equations were discussed under axisymmetric and spherical symmetry conditions. The corresponding equation of isotropic multi-layer hollow spheres was given employing transfer matrix method. To confirm the validity of the frequency equation and explore the feasibility of RUS for characterizing the ICF capsules, three representative capsules with a millimeter-sized diameter were determined by piezoelectric-based resonant ultrasound spectroscopy (PZT-RUS) and laser-based resonant ultrasound spectroscopy (LRUS) techniques. On the basis of both theoretical and experimental results, it is proved that the calculated and measured natural frequencies are accurate enough for determining the ICF capsules.

  8. In Vivo and In Situ Detection of Macromolecular Free Radicals Using Immuno-Spin Trapping and Molecular Magnetic Resonance Imaging.

    Science.gov (United States)

    Towner, Rheal A; Smith, Nataliya

    2017-12-11

    In vivo free radical imaging in preclinical models of disease has become a reality. Free radicals have traditionally been characterized by electron spin resonance (ESR) or electron paramagnetic resonance (EPR) spectroscopy coupled with spin trapping. The disadvantage of the ESR/EPR approach is that spin adducts are short-lived due to biological reductive and/or oxidative processes. Immuno-spin trapping (IST) involves the use of an antibody that recognizes macromolecular 5,5-dimethyl-pyrroline-N-oxide (DMPO) spin adducts (anti-DMPO antibody), regardless of the oxidative/reductive state of trapped radical adducts. Recent Advances: The IST approach has been extended to an in vivo application that combines IST with molecular magnetic resonance imaging (mMRI). This combined IST-mMRI approach involves the use of a spin-trapping agent, DMPO, to trap free radicals in disease models, and administration of an mMRI probe, an anti-DMPO probe, which combines an antibody against DMPO-radical adducts and an MRI contrast agent, resulting in targeted free radical adduct detection. The combined IST-mMRI approach has been used in several rodent disease models, including diabetes, amyotrophic lateral sclerosis (ALS), gliomas, and septic encephalopathy. The advantage of this approach is that heterogeneous levels of trapped free radicals can be detected directly in vivo and in situ to pin point where free radicals are formed in different tissues. The approach can also be used to assess therapeutic agents that are either free radical scavengers or generate free radicals. Smaller probe constructs and radical identification approaches are being considered. The focus of this review is on the different applications that have been studied, advantages and limitations, and future directions. Antioxid. Redox Signal. 00, 000-000.

  9. Fourier Transform Ion Cyclotron Resonance Mass Spectrometry at the Cyclotron Frequency.

    Science.gov (United States)

    Nagornov, Konstantin O; Kozhinov, Anton N; Tsybin, Yury O

    2017-04-01

    The phenomenon of ion cyclotron resonance allows for determining mass-to-charge ratio, m/z, of an ensemble of ions by means of measurements of their cyclotron frequency, ω c . In Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), the ω c quantity is usually unavailable for direct measurements: the resonant state is located close to the reduced cyclotron frequency (ω + ), whereas the ω c and the corresponding m/z values may be calculated via theoretical derivation from an experimental estimate of the ω + quantity. Here, we describe an experimental observation of a new resonant state, which is located close to the ω c frequency and is established because of azimuthally-dependent trapping electric fields of the recently developed ICR cells with narrow aperture detection electrodes. We show that in mass spectra, peaks close to ω + frequencies can be reduced to negligible levels relative to peaks close to ω c frequencies. Due to reduced errors with which the ω c quantity is obtained, the new resonance provides a means of cyclotron frequency measurements with precision greater than that achieved when ω + frequency peaks are employed. The described phenomenon may be considered for a development into an FT-ICR MS technology with increased mass accuracy for applications in basic research, life, and environmental sciences. Graphical Abstract ᅟ.

  10. Experimental results of high power dual frequency resonant magnet excitation at TRIUMF

    International Nuclear Information System (INIS)

    Reiniger, K.W.; Heritier, G.

    1988-06-01

    We present some results of duel frequency resonant magnet excitation at full power using the old NINA synchrotron dipoles. These tests will simulate a typical resonant cell as proposed for the accelerating rings of the TRIUMF KAON Factory. These test have two main purposes: to verify circuit parameters and component ratings for the dual frequency resonant power supply system; and to measure directly electrical losses in a transverse magnet field, such as eddy current losses in magnet conductors, vacuum tubes and core losses in laminations. These data will be required for the detailed design of the accelerator system components. (Author) (Ref., 9 figs., tab.)

  11. Dual resonant structure for energy harvesting from random vibration sources at low frequency

    Directory of Open Access Journals (Sweden)

    Shanshan Li

    2016-01-01

    Full Text Available We introduce a design with dual resonant structure which can harvest energy from random vibration sources at low frequency range. The dual resonant structure consists of two spring-mass subsystems with different frequency responses, which exhibit strong coupling and broad bandwidth when the two masses collide with each other. Experiments with piezoelectric elements show that the energy harvesting device with dual resonant structure can generate higher power output than the sum of the two separate devices from random vibration sources.

  12. Mechanism of initiation of oxidation in mayonnaise enriched with fish oil as studied by electron spin resonance spectroscopy

    DEFF Research Database (Denmark)

    Thomsen, M.K.; Jacobsen, Charlotte; Skibsted, L.H.

    2000-01-01

    Electron spin resonance spectroscopy (spin trapping technique) has been used to identify the most important single factor for initiation of lipid oxidation in mayonnaise enriched with fish oil. Low pH increases the formation of radicals during incubation under mildly accelerated conditions at 37...... degreesC as quantified using 12-doxylstearic acid. Sugar, NaCl and potassium sorbate have no effect on radical formation while EDTA (down to 50 mug/g) has an antioxidative effect. Iron bound to phosvitin in egg yolk, inactive at pH similar to6, is considered to be exposed to the solvent (the aqueous phase...

  13. Electron paramagnetic resonance (EPR spectral components of spin-labeled lipids in saturated phospholipid bilayers: effect of cholesterol

    Directory of Open Access Journals (Sweden)

    Heverton Silva Camargos

    2013-01-01

    Full Text Available Electron paramagnetic resonance (EPR spectroscopy was used to study the main structural accommodations of spin labels in bilayers of saturated phosphatidylcholines with acyl chain lengths ranging from 16 to 22 carbon atoms. EPR spectra allowed the identification of two distinct spectral components in thermodynamic equilibrium at temperatures below and above the main phase transition. An accurate analysis of EPR spectra, using two fitting programs, enabled determination of the thermodynamic profile for these major probe accommodations. Focusing the analysis on two-component EPR spectra of a spin-labeled lipid, the influence of 40 mol % cholesterol in DPPC was studied.

  14. Unraveling skyrmion spin texture using resonant soft x-ray scattering

    Science.gov (United States)

    Roy, Sujoy

    2015-03-01

    The recent discovery of skyrmions, that were originally predicted in context of high energy physics, in magnetic materials has sparked tremendous interest in the research community due to its rich physics and potential in spintronics applications. Skyrmions have an unusual spin texture that manifests as magnetic knot and can be easily moved around. Understanding the fundamental physics and mechanisms for controlling their dynamical properties presents important scientific challenges. So far experimental verifications of the skyrmions in magnetic systems have come from neutron scattering and Lorentz transmission electron microscopy (TEM) measurements. In this talk we report the first observation of the skyrmions using resonant soft x-ray scattering. We have used soft x-rays tuned to the Cu L3 edge to diffract off the skyrmion lattice in a multiferroic Cu2OSeO3 compound. We show that in Cu2OSeO3 there exist two skyrmion lattices arising due to the two inequivalent Cu-O sublattices that have two different magnetically active d-orbitals. The two skyrmion sublattices are mutually rotated with respect to each other. The angle of rotation could be changed by an external magnetic field, thereby indicating possible existence of a new phase. We have also studied skyrmion spin texture in an ultra-thin Fe/Gd multilayer that shows perpendicular anisotropy. The Fe/Gd sample exhibits a near perfect aligned stripe phase. Within a small range of temperature and magnetic field we observe a hexagonal scattering pattern due to skyrmion bubbles. Analysis of the scattering pattern suggests that the skyrmion lattice unit cell contains two skyrmions. The biskyrmion state is also revealed by Lorentz TEM images. The near room temperature discovery of skyrmion in a technology relevant material is a significant step towards using skyrmions in magnetic devices. Work at LBNL was supported by the Office of Basic Energy Sciences of the U.S. Department of Energy (Contract No. DE-AC02-05CH11231).

  15. Shedding light on axial stress effect on resonance frequencies of nanocantilevers.

    Science.gov (United States)

    Pini, Valerio; Tamayo, Javier; Gil-Santos, Eduardo; Ramos, Daniel; Kosaka, Priscila; Tong, Hien-Duy; van Rijn, Cees; Calleja, Montserrat

    2011-06-28

    The detection back-action phenomenon has received little attention in physical, chemical, and biological sensors based on nanomechanical systems. We show that this effect is very significant in ultrathin bimetallic cantilevers, in which the laser beam that probes the picometer scale vibration largely modifies the resonant frequencies of the system. The light back-action effect is nonlinear, and some resonant frequencies can even be reduced to a half with laser power intensities of 2 mW. We demonstrate that this effect arises from the stress and strain generated by the laser heating. The experiments are explained by two-dimensional nonlinear elasticity theory and supported by finite element simulations. The found phenomenology is intimately connected to the old unsolved problem about the effect of surface stress on the resonance frequency of singly clamped beams. The results indicate that to achieve the ultimate detection limits with nanomechanical resonators one must consider the uncertainty due to the detection back-action.

  16. Resonant frequency analysis on an electrostatically actuated microplate under uniform hydrostatic pressure

    International Nuclear Information System (INIS)

    Li Zhikang; Zhao Libo; Ye Zhiying; Zhao Yulong; Jiang Zhuangde; Wang Hongyan

    2013-01-01

    The resonant frequency of a microplate is influenced by various physical parameters such as mass, surface stress, hydrostatic pressure and electrostatic force. In this paper, the effects of both electrostatic force and uniform hydrostatic pressure on the resonant frequency of a clamped circular microplate are investigated. An approximate solution is derived for the fundamental resonance frequency of the mciroplate under both types of loads using an energy equivalent method. It is found that both electrostatic force and uniform hydrostatic pressure decrease the resonant frequency of the microplate under small deflections. Additionally, the linearized expression of this solution shows that the resonant frequency varies linearly with pressure in the low and ultra-low range, and the corresponding pressure sensitivity depends on the voltage applied to the microplate. The analytical results are well validated by the finite element method. This study may be helpful for the design and optimization of electrostatically actuated resonance devices based on microplates, especially electrostatically actuated low- or ultra-low-pressure sensors. (paper)

  17. Detection of reactive oxygen species in isolated, perfused lungs by electron spin resonance spectroscopy

    Directory of Open Access Journals (Sweden)

    Schudt Christian

    2005-07-01

    Full Text Available Abstract Background The sources and measurement of reactive oxygen species (ROS in intact organs are largely unresolved. This may be related to methodological problems associated with the techniques currently employed for ROS detection. Electron spin resonance (ESR with spin trapping is a specific method for ROS detection, and may address some these technical problems. Methods We have established a protocol for the measurement of intravascular ROS release from isolated buffer-perfused and ventilated rabbit and mouse lungs, combining lung perfusion with the spin probe l-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine (CPH and ESR spectroscopy. We then employed this technique to characterize hypoxia-dependent ROS release, with specific attention paid to NADPH oxidase-dependent superoxide formation as a possible vasoconstrictor pathway. Results While perfusing lungs with CPH over a range of inspired oxygen concentrations (1–21 %, the rate of CP• formation exhibited an oxygen-dependence, with a minimum at 2.5 % O2. Addition of superoxide dismutase (SOD to the buffer fluid illustrated that a minor proportion of this intravascular ROS leak was attributable to superoxide. Stimulation of the lungs by injection of phorbol-12-myristate-13-acetate (PMA into the pulmonary artery caused a rapid increase in CP• formation, concomitant with pulmonary vasoconstriction. Both the PMA-induced CPH oxidation and the vasoconstrictor response were largely suppressed by SOD. When the PMA challenge was performed at different oxygen concentrations, maximum superoxide liberation and pulmonary vasoconstriction occurred at 5 % O2. Using a NADPH oxidase inhibitor and NADPH-oxidase deficient mice, we illustrated that the PMA-induced superoxide release was attributable to the stimulation of NADPH oxidases. Conclusion The perfusion of isolated lungs with CPH is suitable for detection of intravascular ROS release by ESR spectroscopy. We employed this technique to

  18. Electron spin resonance microscopic imaging of oxygen concentration in cancer spheroids

    Science.gov (United States)

    Hashem, Mada; Weiler-Sagie, Michal; Kuppusamy, Periannan; Neufeld, Gera; Neeman, Michal; Blank, Aharon

    2015-07-01

    Oxygen (O2) plays a central role in most living organisms. The concentration of O2 is important in physiology and pathology. Despite the importance of accurate knowledge of the O2 levels, there is very limited capability to measure with high spatial resolution its distribution in millimeter-scale live biological samples. Many of the current oximetric methods, such as oxygen microelectrodes and fluorescence lifetime imaging, are compromised by O2 consumption, sample destruction, invasiveness, and difficulty to calibrate. Here, we present a new method, based on the use of the pulsed electron spin resonance (ESR) microimaging technique to obtain a 3D mapping of oxygen concentration in millimeter-scale biological samples. ESR imaging requires the incorporation of a suitable stable and inert paramagnetic spin probe into the desirable object. In this work, we use microcrystals of a paramagnetic spin probe in a new crystallographic packing form (denoted tg-LiNc-BuO). These paramagnetic species interact with paramagnetic oxygen molecules, causing a spectral line broadening that is linearly proportional to the oxygen concentration. Typical ESR results include 4D spatial-spectral images that give an indication about the oxygen concentration in different regions of the sample. This new oximetry microimaging method addresses all the problems mentioned above. It is noninvasive, sensitive to physiological oxygen levels, and easy to calibrate. Furthermore, in principle, it can be used for repetitive measurements without causing cell damage. The tissue model used in this research is spheroids of Human Colorectal carcinoma cell line (HCT-116) with a typical diameter of ∼600 μm. Most studies of the microenvironmental O2 conditions inside such viable spheroids carried out in the past used microelectrodes, which require an invasive puncturing of the spheroid and are also not applicable to 3D O2 imaging. High resolution 3D oxygen maps could make it possible to evaluate the

  19. Simulation of electron spin resonance spectroscopy in diverse environments: An integrated approach

    Science.gov (United States)

    Zerbetto, Mirco; Polimeno, Antonino; Barone, Vincenzo

    2009-12-01

    We discuss in this work a new software tool, named E-SpiReS (Electron Spin Resonance Simulations), aimed at the interpretation of dynamical properties of molecules in fluids from electron spin resonance (ESR) measurements. The code implements an integrated computational approach (ICA) for the calculation of relevant molecular properties that are needed in order to obtain spectral lines. The protocol encompasses information from atomistic level (quantum mechanical) to coarse grained level (hydrodynamical), and evaluates ESR spectra for rigid or flexible single or multi-labeled paramagnetic molecules in isotropic and ordered phases, based on a numerical solution of a stochastic Liouville equation. E-SpiReS automatically interfaces all the computational methodologies scheduled in the ICA in a way completely transparent for the user, who controls the whole calculation flow via a graphical interface. Parallelized algorithms are employed in order to allow running on calculation clusters, and a web applet Java has been developed with which it is possible to work from any operating system, avoiding the problems of recompilation. E-SpiReS has been used in the study of a number of different systems and two relevant cases are reported to underline the promising applicability of the ICA to complex systems and the importance of similar software tools in handling a laborious protocol. Program summaryProgram title: E-SpiReS Catalogue identifier: AEEM_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEM_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GPL v2.0 No. of lines in distributed program, including test data, etc.: 311 761 No. of bytes in distributed program, including test data, etc.: 10 039 531 Distribution format: tar.gz Programming language: C (core programs) and Java (graphical interface) Computer: PC and Macintosh Operating system: Unix and Windows Has the code been vectorized or

  20. Design of LCL Filters With LCL Resonance Frequencies Beyond the Nyquist Frequency for Grid-Connected Converters

    DEFF Research Database (Denmark)

    Tang, Yi; Yao, Wenli; Loh, Poh Chiang

    2016-01-01

    -switch-based three-phase pulsewidth-modulated converters. Moreover, a single-loop current control strategy is proposed for the designed LCL filter, and the control system is inherently stable without introducing any passive or active damping. Based on the new stability region, two LCL filter design...... examples are given, with one of them optimizing the utilization of passive filter inductors, and another one being robust against grid impedance variation. Comprehensive experimental results, showing the high-quality output current and excellent resonance attenuation, are presented in this paper, which......This paper proposes a novel LCL filter design method and its current control for grid-connected converters. With the proposed design method, it is possible to set the resonance frequency of the LCL filter to be higher than the Nyquist frequency, i.e., half of the system sampling frequency...

  1. The resonance frequency of SonoVue (tm) as observed by high-speed optical imaging

    NARCIS (Netherlands)

    van der Meer, S.M.; Versluis, Michel; Lohse, Detlef; Chin, C.T.; Bouakaz, A.; de Jong, N.

    2004-01-01

    The resonance frequencies of individual SonoVue/spl trade/ contrast agent bubbles were measured optically by recording the radius-time curves of a single microbubble at 24 different frequencies. For these experiments, the Brandaris 128 fast framing camera was operated in a special segmented mode.

  2. Theoretical analysis of the multiple resonances for many-level spin systems. The four-level spin system of s electron ions subjected to strong microwave fields

    International Nuclear Information System (INIS)

    Popescu, F.F.; Marica, F.

    1994-01-01

    The analytic steady state solutions of master equation for the density matrix of a multilevel spin system in dilute paramagnetic crystals at high temperature, subjected to strong microwave fields, are discussed. These solutions enable to obtain the populations of the levels, and the microwave powers absorbed or emitted by the crystal, in the presence of one, two or more microwave fields. A detailed theoretical study of the maser effects for s electron ions with nuclear spin one-half is carried out. In the case of three frequency correlated strong fields, when 'the spectroscopic' bridge conditions are fulfilled, sensitive detections, or high efficient generations of microwaves of frequency higher than those of the pumping fields are predicted. (author) 16 figs., 16 refs

  3. Measurement of a hyperfine-induced spin-exchange frequency shift in atomic hydrogen

    International Nuclear Information System (INIS)

    Walsworth, R.L.; Silvera, I.F.; Mattison, E.M.; Vessot, R.F.C.

    1992-01-01

    We have measured a hyperfine-induced spin-exchange frequency shift in the atomic-hydrogen ground-state hyperfine transition. A recent quantum-mechanical treatment of low-energy hydrogen-hydrogen scattering by Koelman et al. [Phys. Rev. A 38, 3535 (1988)] predicts such frequency shifts to become large at low temperature, and to affect the performance of atomic clocks such as the cryogenic hydrogen maser. The experiment reported here was performed with a hydrogen maser operating near room temperature, where the reported hyperfine effects are predicted to be small, but measurable. Using an adiabatic fast passage (AFP) technique to vary the incoming atomic population in the masing states from approximately 100% (AFP on) to 50% (AFP off), we determined the change in the dimensionless hyperfine-induced frequency-shift parameter Ω to be Ω on -Ω off =5.38 (1.06)x10 -4 . The theoretical prediction at this temperature is Ω on -Ω off =-0.76x10 -4 to -1.12x10 -4 , for the range of masing-state populations used in the present experiment. We review the relevant theory, report our experimental method and results, and discuss possible reasons for the discrepancy between experiment and theory

  4. Resonance frequency control of RF normal conducting cavity using gradient estimator of reflected power

    Science.gov (United States)

    Leewe, R.; Shahriari, Z.; Moallem, M.

    2017-10-01

    Control of the natural resonance frequency of an RF cavity is essential for accelerator structures due to their high cavity sensitivity to internal and external vibrations and the dependency of resonant frequency on temperature changes. Due to the relatively high radio frequencies involved (MHz to GHz), direct measurement of the resonant frequency for real-time control is not possible by using conventional microcontroller hardware. So far, all operational cavities are tuned using phase comparison techniques. The temperature dependent phase measurements render this technique labor and time intensive. To eliminate the phase measurement, reduce man hours and speed up cavity start up time, this paper presents a control theme that relies solely on the reflected power measurement. The control algorithm for the nonlinear system is developed through Lyapunov's method. The controller stabilizes the resonance frequency of the cavity using a nonlinear control algorithm in combination with a gradient estimation method. Experimental results of the proposed system on a test cavity show that the resonance frequency can be tuned to its optimum operating point while the start up time of a single cavity and the accompanied man hours are significantly decreased. A test result of the fully commissioned control system on one of TRIUMF's DTL tanks verifies its performance under real environmental conditions.

  5. Measurements of time average series resonance effect in capacitively coupled radio frequency discharge plasma

    International Nuclear Information System (INIS)

    Bora, B.; Bhuyan, H.; Favre, M.; Wyndham, E.; Chuaqui, H.; Kakati, M.

    2011-01-01

    Self-excited plasma series resonance is observed in low pressure capacitvely coupled radio frequency discharges as high-frequency oscillations superimposed on the normal radio frequency current. This high-frequency contribution to the radio frequency current is generated by a series resonance between the capacitive sheath and the inductive and resistive bulk plasma. In this report, we present an experimental method to measure the plasma series resonance in a capacitively coupled radio frequency argon plasma by modifying the homogeneous discharge model. The homogeneous discharge model is modified by introducing a correction factor to the plasma resistance. Plasma parameters are also calculated by considering the plasma series resonances effect. Experimental measurements show that the self-excitation of the plasma series resonance, which arises in capacitive discharge due to the nonlinear interaction of plasma bulk and sheath, significantly enhances both the Ohmic and stochastic heating. The experimentally measured total dissipation, which is the sum of the Ohmic and stochastic heating, is found to increase significantly with decreasing pressure.

  6. Active cooling of an audio-frequency electrical resonator to microkelvin temperatures

    Science.gov (United States)

    Vinante, A.; Bonaldi, M.; Mezzena, R.; Falferi, P.

    2010-11-01

    We have cooled a macroscopic LC electrical resonator using feedback-cooling combined with an ultrasensitive dc Superconducting Quantum Interference Device (SQUID) current amplifier. The resonator, with resonance frequency of 11.5 kHz and bath temperature of 135 mK, is operated in the high coupling limit so that the SQUID back-action noise overcomes the intrinsic resonator thermal noise. The effect of correlations between the amplifier noise sources clearly show up in the experimental data, as well as the interplay of the amplifier noise with the resonator thermal noise. The lowest temperature achieved by feedback is 14 μK, corresponding to 26 resonator photons, and approaches the limit imposed by the noise energy of the SQUID amplifier.

  7. Off-resonance frequency operation for power transfer in a loosely coupled air core transformer

    Science.gov (United States)

    Scudiere, Matthew B

    2012-11-13

    A power transmission system includes a loosely coupled air core transformer having a resonance frequency determined by a product of inductance and capacitance of a primary circuit including a primary coil. A secondary circuit is configured to have a substantially same product of inductance and capacitance. A back EMF generating device (e.g., a battery), which generates a back EMF with power transfer, is attached to the secondary circuit. Once the load power of the back EMF generating device exceeds a certain threshold level, which depends on the system parameters, the power transfer can be achieved at higher transfer efficiency if performed at an operating frequency less than the resonance frequency, which can be from 50% to 95% of the resonance frequency.

  8. A frequency tuner for resonant inverters suitable for magnetic hyperthermia applications

    Science.gov (United States)

    Mazon, E. E.; Sámano, A. H.; Calleja, H.; Quintero, L. H.; Paz, J. A.; Cano, M. E.

    2017-09-01

    In this study, a frequency tuner system is developed for generating variable frequency magnetic fields for magnetic hyperthermia applications. The tuning device contains three specially designed phase lock loop devices that drive a resonant inverter working in the frequency band of 180-525 kHz. This tuner system can be adapted for other resonant inverters employed in the studies of ferrofluids with superparamagnetic nanoparticles. The performance of the whole system is also examined. Our findings were in agreement with the theoretical expectations of phase locking and frequency tuning. The system is tested for samples of a solid magnetic material of cylindrical shape and ferrofluids with differing concentrations of powdered magnetite. The observations indicate significant frequency changes of the magnetic field due to heating of the samples. These frequency variations can be a source of errors, which should not be neglected in experiments determining the specific absorption rate or power dissipated density.

  9. Identification of irradiated wheat by germination test, DNA comet assay and electron spin resonance

    Science.gov (United States)

    Barros, Adilson C.; Freund, Maria Teresa L.; Villavicencio, Ana Lúcia C. H.; Delincée, Henry; Arthur, Valter

    2002-03-01

    In several countries, there has been an increase in the use of radiation for food processing thus improving the quality and sanitary conditions, inhibiting pathogenic microorganisms, delaying the natural aging process and so extending product lifetime. The need to develop analytical methods to detect these irradiated products is also increasing. The goal of this research was to identify wheat irradiated using different radiation doses. Seeds were irradiated with a gamma 60Co source (Gammacell 220 GC) in the Centro de Energia Nuclear na Agricultura and the Instituto de Pesquisas Energéticas e Nucleares. Dose rate used were 1.6 and 5.8kGy/h. Applied doses were 0.0, 0.10, 0.25, 0.50, 0.75, 1.0, and 2.0kGy. After irradiation, seeds were analysed over a 6 month period. Three different detection methods were employed to determine how irradiation had modified the samples. Screening methods consisted of a germination test measuring the inhibition of shooting and rooting and analysis of DNA fragmentation. The method of electron spin resonance spectroscopy allowed a better dosimetric evaluation. These techniques make the identification of irradiated wheat with different doses possible.

  10. Variability of electron spin resonance (ESR) signal of γ -irradiated starches

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Gilberto D.; Rodrigues Junior, Orlando; Mastro, Nelida L. del, E-mail: nlmastro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2017-11-01

    Food preservation is one of the practical applications of radiation processing of materials. Starch is an abundant and cheap nutritious biopolymer and also is the material for appropriate food systems and for technical industries. Starch granules are partially crystalline structures composed mainly of two types of starch: amylose, an essentially linear polymer, and amylopectin, with 3-44% of branch points. Electron spin resonance (ESR) spectroscopy is a very powerful and sensitive method for the characterization of the electronic structures of materials with unpaired electrons. The aim of the present work was to monitor the disappearance of the short life and long-life free radicals formed during γ-irradiation of 3 different starches. Corn, potato and fermented cassava starches were irradiated in a {sup 60}Co source Gammacell 220 with 20 kGy, dose rate around 1 kGy h{sup -1}. EPR spectra were obtained at room temperature using a Bruker EMX plus model, X band equipment. The main type of ESR signal from irradiated starch is a singlet with a g-value of about 2.0. The fading of ESR signals was followed for 350 hours, and presents differences among the different starch type reflecting differences in molecular arrangements of starch crystalline and amorphous fractions, although ESR spectra seemed to be common for all starches. (author)

  11. Electron spin resonance of X-irradiated single crystal of calcium tartrate tetrahydrate

    International Nuclear Information System (INIS)

    Korkmaz, M.

    1977-01-01

    The electron spin resonance spectra of an irradiated single crystal of calcium tartrate tetrahydrate grown from silica gel have been investigated. Only one species of free radical was observed at room and liquid nitrogen temperatures. The free radical was found to be the result of the splitting of a C-H bond adjacent to both the hydroxyl and carboxyl groups. For some orientations of the crystal in the external magnetic field two unresolved doublets, due to two noequivalent protons, was observed. The g factor was found to be almost isotropic, with a value of 2.0032 +- 0.0005. Couplings with two H nuclei are believed to be the result of the proton of the hydroxyl group attached directly to the unsaturated asymmetric carbon atom and of the proton attached directly to the other asymmetric carbon atom of the molecule. The principal elements of the nuclear coupling of these protons are 5.8, 7.9, 3.7 and 6.8, 7.0, 17.3 G respectively. The radical was found to be very stable, the ESR pattern being undiminished for more than half a year after the irradiation. (author)

  12. Gas chromatographic and electron spin resonance investigations of gamma-irradiated frog legs

    International Nuclear Information System (INIS)

    Morehouse, K.M.; Ku, Yuoh; Albrecht, H.L.; Yang, G.C.

    1991-01-01

    Several very sensitive techniques to measure radiation-induced products in frog legs were investigated. Presented here are results from the use of electron spin resonance (ESR) spectroscopy and capillary gas chromatography (GC) to measure radiolysis products in γ-irradiated frog legs. When bone is irradiated, a characteristic ESR signal develops and is easily measured. The intensity of the ESR signal is dose-dependent and stable for several months at room temperature. When triglycerides or fatty acids are irradiated, some of the major stable products formed are hydrocarbons with one less carbon than the precursor fatty acids. These hydrocarbons are formed as the result of the loss of CO 2 during various free radical reactions. A capillary GC procedure was developed to monitor the formation of these hydrocarbons in γ-irradiated frog legs. Since frog legs contain large amounts of palmitic, stearic, oleic, and linoleic acids, the formation of the hydrocarbons (pentadecane, heptadecane, 8-heptadecene, and 6,9-heptadecadiene, respectively) from the decarboxylation of these fatty acids was monitored. The yields of these hydrocarbons were found to be linear with applied dose. A sample from a lot of imported frog legs that were believed to have been treated with ionizing radiation was also analyzed. The ESR technique, in conjunction with the GC data on the hydrocarbons, appears to be a useful approach for identifying and monitoring frog legs that have been treated with ionizing radiation. (author)

  13. Electron spin resonance characterization of trapping centers in Unibond reg-sign buried oxides

    International Nuclear Information System (INIS)

    Conley, J.F. Jr.; Lenahan, P.M.; Wallace, B.D.

    1996-01-01

    Electron spin resonance and capacitance vs. voltage measurements are used to evaluate the radiation response of Unibond buried oxides. When damaged by hole injection, it is found that Unibond reg-sign buried oxides exhibit a rough correspondence between E' centers and positive charge as well as generation of P b centers at the Unibond buried oxide/Si interface. In these respects, Unibond buried oxides qualitatively resemble thermal SiO 2 . However, a hydrogen complexed E' center known as the 74 G doublet is also detected in the Unibond buried oxides. This defect is not detectable in thermal SiO 2 under similar circumstances. Since the presence of 74 G doublet center is generally indicative of very high hydrogen content and since hydrogen is clearly a significant participant in radiation damage, this result suggests a qualitative difference between the radiation response of Unibond and thermal SiO 2 . Unibond results are also compared and contrasted with similar investigations on separation-by-implanted-oxygen (SIMOX) buried oxides. Although the charge trapping response of Unibond buried oxides may be inferior to that of radiation hardened thermal SiO 2 , it appears to be more simple and superior to that of SIMOX buried oxides

  14. Electron spin resonance characterization of radical components in irradiated black pepper skin and core

    Energy Technology Data Exchange (ETDEWEB)

    Yamaoki, Rumi, E-mail: yamaoki@gly.oups.ac.jp [Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094 (Japan); Kimura, Shojiro [Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094 (Japan); Ohta, Masatoshi [Faculty of Engineering, Niigata University, 8050 Igarashi 2-no-cho, Nishi-ku, Niigata 950-2181 (Japan)

    2011-11-15

    Characteristics of free radical components of irradiated black pepper fruit (skin) and the pepper seed (core) were analyzed using electron spin resonance. A weak signal near g=2.005 was observed in black pepper before irradiation. Complex spectra near g=2.005 with three lines (the skin) or seven lines (the core) were observed in irradiated black pepper (both end line width; ca. 6.8 mT). The spectral intensities decreased considerably at 30 days after irradiation, and continued to decrease steadily thereafter. The spectra simulated on the basis of the content and the stability of radical components derived from plant constituents, including fiber, starch, polyphenol, mono- and disaccharide, were in good agreement with the observed spectra. Analysis showed that the signal intensities derived from fiber in the skin for an absorbed dose were higher, and the rates of decrease were lower, than that in the core. In particular, the cellulose radical component in the skin was highly stable. - Highlights: > We identified the radical components in irradiated black pepper skin and core. > The ESR spectra near g=2.005 with 3-7 lines were emerged after irradiation. > Spectra simulated basing on the content and the stability of radical from the plant constituents. > Cellulose radical component in black pepper skin was highly stable. > Single signal near g=2.005 was the most stable in black pepper core.

  15. Cyclic voltammetry, spectroelectrochemistry and electron spin resonance as combined tools to study thymoquinone in aprotic medium

    International Nuclear Information System (INIS)

    Petrucci, Rita; Marrosu, Giancarlo; Astolfi, Paola; Lupidi, Giulio; Greci, Lucedio

    2012-01-01

    Nigella sativa has been used for centuries as a natural remedy for a number of chronic and age-related diseases. Thymoquinone (TQ), the main constituent of its extracts, has recently received particular attention and has been tested for its antioxidant, anti-inflammatory and anticancer properties. To further investigate the mechanisms involved in the biological activities of this natural quinone and, among these, in its antioxidant properties, the redox-system of TQ and its interaction with superoxide was studied in aprotic medium by cyclic voltammetry, spectroelectrochemistry and Electron Spin Resonance (ESR). The electrochemical behavior of dithymoquinone (DTQ), the photodimer of TQ, was also studied in the same medium. Experimental data evidenced the formation of the radical anion TQ· − by cathodic reduction of TQ at potential values very close to coenzymes Q ones, by electron transfer (ET) between TQ and superoxide, as KO 2 or electrogenerated, by chemical comproportionation between TQ and the dianion TQ −− and by fast cleavage of the electrogenerated radical anion DTQ· − . Spectroelectrochemical data evidenced that TQ· − , in the presence of TQ, evolves to the hydroquinone monoanion TQH − , suggesting that an H-atom transfer (HT) may occur, likely from the isopropylic side-chain of TQ to TQ· − The H-atom donating ability of TQ may be also supported by Bond Dissociation Energy values and ESR data.

  16. Formation of radicals in coal pyrolysis examined by electron spin resonance

    Science.gov (United States)

    Chang, Tong; Guo, Qiang; Hao, Haigang; Wu, Baoshan; Yang, Yong

    2017-09-01

    Electron spin resonance (ESR) spectroscopy is used to study materials with unpaired electrons, such as organic radicals and metal complexes. This method can also be used to follow radical reactions during pyrolysis of carbonaceous materials. However, the temperature dependence of ESR measurement should be considered. To enable reasonable comparisons, results measured at different temperatures must be converted. In this study, we investigated the behavior of free radicals in the process of coal pyrolysis using in situ and ex situ ESR. The ESR data were collected at both pyrolysis and room temperatures, and apparent differences were analyzed. The differences were diminished when our data were converted to the same measurement temperature level based on the Boltzmann distribution law. Furthermore, we investigated the effects of process conditions on the behavior of free radicals in the solid phase of coal. We found that temperature is the most important factor determining the formation and behavior of free radicals in the solid phase, followed by the residence time. Relatively active radicals were quenched by hydrogen-donor solvents to some degree, while stable radicals remained.

  17. Electron spin resonance dating of megafauna from Lagoa dos Porcos, Piauí, Brazil.

    Science.gov (United States)

    Kinoshita, Angela; Mayer, Elver; Ribau Mendes, Vinícius; Figueiredo, Ana Maria G; Baffa, Oswaldo

    2014-06-01

    Excavations performed at Lagoa dos Porcos site revealed a vast amount of extinct mammal fossil remains, becoming one of the richest palaeontological occurrences in the Serra da Capivara National Park region, a UNESCO World Heritage. Although anatomic and taxonomic aspects of extinct Quaternary mammals are relatively well known, chronologic information for deposits is rare. In this context, electron spin resonance (ESR) dating of megafauna samples provides important information for establishing a chronological background. This work presents the ESR dating of two teeth, one of Gomphotheriidae and other of Toxodontinae. Dose-response curves of each sample were constructed using spectra acquired with a JEOL FA-200 X-Band spectrometer resulting in equivalent dose (De) of 220 ± 40 Gy and 39 ± 2 Gy for Toxodontinae and Gomphotheriidae tooth, respectively. The conversion of De in age was made using ROSY ESR dating software resulting in 26 ± 4 and 22 ± 3 ka. These results place Lagoa dos Porcos fossil assemblage within the Late Pleistocene. These dates overlap with a period of abrupt increase in rainfall in northeast Brazil, and it is possible that this environmental change is related to the formation of this deposit. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Electron spin resonance dating of mega-fauna from Lagoa dos Porcos, Piaui (Brazil))

    International Nuclear Information System (INIS)

    Kinoshita, Angela; Mayer, Elver; Ribau Mendes, Vinicius; Figueiredo, Ana Maria G.; Baffa, Oswaldo

    2014-01-01

    Excavations performed at Lagoa dos Porcos site revealed a vast amount of extinct mammal fossil remains, becoming one of the richest palaeontological occurrences in the Serra da Capivara National Park region, a UNESCO World Heritage. Although anatomic and taxonomic aspects of extinct Quaternary mammals are relatively well known, chronologic information for deposits is rare. In this context, electron spin resonance (ESR) dating of mega-fauna samples provides important information for establishing a chronological background. This work presents the ESR dating of two teeth, one of Gomphotheriidae and other of Toxodontinae. Dose-response curves of each sample were constructed using spectra acquired with a JEOL FA-200 X-Band spectrometer resulting in equivalent dose (D e ) of 220±40 Gy and 39±2 Gy for Toxodontinae and Gomphotheriidae tooth, respectively. The conversion of D e in age was made using ROSY ESR dating software resulting in 26±4 and 22±3 ka. These results place Lagoa dos Porcos fossil assemblage within the Late Pleistocene. These dates overlap with a period of abrupt increase in rainfall in northeast Brazil, and it is possible that this environmental change is related to the formation of this deposit. (authors)

  19. Tooth enamel electron spin resonance dosimetry of people living in the area with lime tobacco custom

    International Nuclear Information System (INIS)

    Jiao Ling; Zhang Wenyi; Ding Yanqiu

    2010-01-01

    Objective: To study the effect of the custom of long term chewing lime tobacco on human tooth enamel electron spin resonance (ESR) dosimetry. Methods: A total of 20 enamel samples from lingual parts of adults teeth collected in Bombay, India were obtained by mechanical method. Some enamel samples from Japanese adults were extracted and 10 mixed samples were prepared. Enamel samples were exposed to different doses of 60 Co γ-rays several times, and ESR spectra were measured after exposure. Results: ESR background signals of 9 Bombay samples were found 1.5-3.3 times higher than those of Japanese mixed samples. The γ-ray dose responses of dosimetric signal with higher background level were a little lower, and the average sensitivity was (0.42±0.03) mGy, which was close to that of Japanese mixed samples. Conclusions: The average level of background signals of Bombay samples was much higher than that of other non-chewing tobacco area, which was possibly caused by tobacco area, which was possibly caused by tobacco lime, the main component in chewing tobacco productions, and it would help to explore its special influences on ESR, and improve dose reconstruction in accuracy. (authors)

  20. Ultra high resolution neutron scattering: Neutron Resonance Spin-Echo and Larmor Diffraction

    Science.gov (United States)

    Walters, Andrew; Keller, Thomas; Keimer, Bernhard

    2012-02-01

    The TRISP spectrometer at the FRM II neutron source near Munich, Germany, is a unique world-leading neutron scattering instrument which employs the Neutron Resonance Spin-Echo technique (NRSE). Linewidths of dispersive excitations with energy transfers up to 50 meV can be measured with an energy resolution in the μeV range without the restrictive flux limitations that normally apply to high resolution neutron triple-axis spectrometers. Pioneering studies on the electron-phonon interaction in elemental superconductorsootnotetextP. Aynajian et al., Science 319 1509 (2008) and the lifetimes of magnetic excitations in archetypal magnetic systems will be reviewed.ootnotetextS. Bayrakci et al., Science 312 1928 (2006) The instrument can also be used as a Larmor diffractometer, enabling d-spacings to be measured with a resolution of δdd ˜10-6, i.e. more than one order of magnitude more sensitive than conventional diffraction techniques.ootnotetextC. Pfleiderer et al., Science 316 1871 (2007) Ongoing and future NRSE and Larmor diffraction projects will be outlined, especially in regard to prospective studies which will take full advantage of the new low temperature and high pressure sample environment capabilities now available at TRISP.

  1. Electron spin resonance. Part two: a diagnostic method in the environmental sciences.

    Science.gov (United States)

    Rhodes, Christopher J

    2011-01-01

    A review is presented of some of the ways in which electron spin resonance (ESR) spectroscopy may be useful to investigate systems of relevance to the environmental sciences. Specifically considered are: quantititave ESR, photocatalysis for pollution control; sorption and mobility of molecules in zeolites; free radicals produced by mechanical action and by shock waves from explosives; measurement of peroxyl radicals and nitrate radicals in air; determination of particulate matter polyaromatic hydrocarbons (PAH), soot and black carbon in air; estimation of nitrate and nitrite in vegetables and fruit; lipid-peroxidation by solid particles (silica, asbestos, coal dust); ESR of soils and other biogenic substances: formation of soil organic matter carbon capture and sequestration (CCS) and no-till farming; detection of reactive oxygen species in the photosynthetic apparatus of higher plants under light stress; molecular mobility and intracellular glasses in seeds and pollen; molecular mobility in dry cotton; characterisation of the surface of carbon black used for chromatography; ESR dating for archaeology and determining seawater levels; measurement of the quality of tea-leaves by ESR; green-catalysts and catalytic media; studies of petroleum (crude oil); fuels; methane hydrate; fuel cells; photovoltaics; source rocks; kerogen; carbonaceous chondrites to find an ESR-based marker for extraterrestrial origin; samples from the Moon taken on the Apollo 11 and Apollo 12 missions to understand space-weathering; ESR studies of organic matter in regard to oil and gas formation in the North Sea; solvation by ionic liquids as green solvents, ESR in food and nutraceutical research.

  2. ESR (Electronic Spin Resonance Spectroscopy) study of irradiated paper for biomedical material wrapping

    International Nuclear Information System (INIS)

    Huarte, Monica; Rubin de Celis, Emilio; Kairiyama, Eulogia; Zapata, Miguel; Santoro, Natalia; Magnavacca, Cecilia

    2009-01-01

    Ionising radiation treatments are used for sterilization, microbiological decontamination, disinfection, insect disinfestation and food preservation. This ionising radiation generates free radicals (FR) in matter, which can be detected by Electronic Spin Resonance Spectroscopy (ESR). For this work it had analysed different kind of irradiated package papers of syringes, surgical gloves and dressings by ESR. These were irradiated with doses between 20 and 35 kGy of gamma radiation (Cobalt 60). The processed samples were measured in a Bruker ECS 106 spectrometer. The obtained results were: 1-) The irritated samples showed a central peak and two satellites induced by the applied radiation; 2-) The non-irradiated samples did not show the characteristic satellite peaks of the irritated ones; 3-) A linear relationship between the signal heights per unit mass and the applied doses was found; and 4-) The signals were highly stable, with half-time values between 240 and 370 days for 20 and 30 kGy, permitting more than one year of monitoring proceedings. In conclusion, the ESR allows the detection, quantification and time monitoring processes of this kind of irradiated materials. (author) [es

  3. Electron spin resonance and thermoluminescence in powder form of clear fused quartz: effects of grinding

    CERN Document Server

    Ranjbar, A H; Randle, K

    1999-01-01

    Clear fused quartz (CFQ) tubes were powdered either manually by using a mortar and pestle (for coarse production) or mechanically, using a micronising mill (for fine production). A high and multisignal electron spin resonance (ESR) background was found in the fine powder even after annealing it at 900 deg. C for 20 min. In the case of the coarse powder, the signal (ESR background) varied inversely with particle size and was quite high for particle sizes lower than 38 mu m. In a subsidiary experiment, using fine SiO sub 2 powder (99.8% pure, with the particle size of approx 0.007 mu m), manufactured by using flame hydrolysis, only a weak background signal was found. The sup 6 sup 0 Co gamma-ray irradiated powders (approx 22 Gy) were subjected to ESR analysis or thermoluminescence (TL) readout. The ESR intensity of the coarse powder varied directly with particle size. Thus, the intensity for a particle size of 20-38 mu m was very low and almost the same as the unirradiated intensity. In TL readout the results w...

  4. Formation of radicals in coal pyrolysis examined by electron spin resonance

    Directory of Open Access Journals (Sweden)

    Tong Chang

    2017-09-01

    Full Text Available Electron spin resonance (ESR spectroscopy is used to study materials with unpaired electrons, such as organic radicals and metal complexes. This method can also be used to follow radical reactions during pyrolysis of carbonaceous materials. However, the temperature dependence of ESR measurement should be considered. To enable reasonable comparisons, results measured at different temperatures must be converted. In this study, we investigated the behavior of free radicals in the process of coal pyrolysis using in situ and ex situ ESR. The ESR data were collected at both pyrolysis and room temperatures, and apparent differences were analyzed. The differences were diminished when our data were converted to the same measurement temperature level based on the Boltzmann distribution law. Furthermore, we investigated the effects of process conditions on the behavior of free radicals in the solid phase of coal. We found that temperature is the most important factor determining the formation and behavior of free radicals in the solid phase, followed by the residence time. Relatively active radicals were quenched by hydrogen-donor solvents to some degree, while stable radicals remained.

  5. Electron-spin-resonance study of radiation-induced paramagnetic defects in oxides grown on (100) silicon substrates

    International Nuclear Information System (INIS)

    Kim, Y.Y.; Lenahan, P.M.

    1988-01-01

    We have used electron-spin resonance to investigate radiation-induced point defects in Si/SiO 2 structures with (100) silicon substrates. We find that the radiation-induced point defects are quite similar to defects generated in Si/SiO 2 structures grown on (111) silicon substrates. In both cases, an oxygen-deficient silicon center, the E' defect, appears to be responsible for trapped positive charge. In both cases trivalent silicon (P/sub b/ centers) defects are primarily responsible for radiation-induced interface states. In earlier electron-spin-resonance studies of unirradiated (100) substrate capacitors two types of P/sub b/ centers were observed; in oxides prepared in three different ways only one of these centers, the P/sub b/ 0 defect, is generated in large numbers by ionizing radiation

  6. Open Resonator for Summation of Powers in Sub-Terahertz and Terahertz Frequencies

    Science.gov (United States)

    Kuz'michev, I. K.; Yeryomka, V. D.; May, A. V.; Troshchilo, A. S.

    2017-03-01

    Purpose: Study of excitation features for the first higher axialasymmetric type oscillations in an open resonator connected into the waveguide transmission line. Design/methodology/approach: To determine the efficiency of higher oscillation excitation in the resonator by using the highest wave of a rectangular waveguide, the coefficient of the antenna surface utilization is used. The coefficient of reflection from the open resonator is determined by the known method of summation of the partial coefficients of reflection from the resonant system. Findings: The excitation efficiency of the first higher axial asymmetric type TEM10q oscillations in an open resonator connected into the waveguide transmission line, using the TE20 type wave, is considered. The research efforts were made with accounting for the electromagnetic field vector nature. It is shown that for certain sizes of exciting coupler the excitation efficiency of the working excitation is equal to 0.867. Besides, this resonant system has a single frequency response within a wide band of frequencies. Due to this, it can be applied for summation of powers for individual sources of oscillations. Since this resonant system allows separating the matching functions as to the field and coupling, it is possible to provide any prescribed coupling of sources with a resonant volume. For this purpose, one- dimensional diffraction gratings (E-polarization) are used. Conclusions: With the matched excitation of axially asymmetric modes of oscillations the resonant system has an angular and frequency spectrum selection that is of great practical importance for powers summation. By application of one- dimensional diffraction gratings (E-polarization), located in apertures of coupling elements, the active elements can be matched with the resonant volume.

  7. Polarization study of non-resonant X-ray magnetic scattering from spin-density-wave modulation in chromium

    International Nuclear Information System (INIS)

    Ohsumi, Hiroyuki; Takata, Masaki

    2007-01-01

    We present a polarization study of non-resonant X-ray magnetic scattering in pure chromium. Satellite reflections are observed at +/-Q and +/-2Q, where Q is the modulation wave vector of an itinerant spin-density-wave. The first and second harmonics are confirmed to have magnetic and charge origin, respectively, by means of polarimetry without using an analyzer crystal. This alternative technique eliminates intolerable intensity loss at an analyzer by utilizing the sample crystal also as an analyzer crystal

  8. Electron Spin Resonance study of charge trapping in α-ZnMoO.sub.4./sub. single crystal scintillator

    Czech Academy of Sciences Publication Activity Database

    Buryi, Maksym; Spassky, D.A.; Hybler, Jiří; Laguta, Valentyn; Nikl, Martin

    2015-01-01

    Roč. 47, Sep (2015), 244-250 ISSN 0925- 3467 R&D Projects: GA MŠk LO1409; GA MŠk(CZ) LM2011029; GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : Electron Spin Resonance * scintillator * charge traps * zinc molybdate Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.183, year: 2015

  9. METAL OXIDE DOPED ANTIBACTERIAL POLYMERIC COATED TEXTILE MATERIALS AND ASSESSEMENT OF ANTIBACTERIAL ACTIVITY WITH ELECTRON SPIN RESONANCE

    Directory of Open Access Journals (Sweden)

    GEDIK Gorkem

    2017-05-01

    Full Text Available Antibacterial activity of a food conveyor belt is an essential property in some cases. However, every antibacterial chemical is not suitable to contact with food materials. Many metal oxides are suitable option for this purpose. The aim of this study was to investigate antibacterial properties of zinc oxide doped PVC polymer coated with electron spin resonance technique. Therefore, optimum zinc oxide containing PVC paste was prepared and applied to textile surface. Coating construction was designed as double layered, first layer did not contain antibacterial agent, thin second layer contained zinc oxide at 10-35% concentration. Oxygen radicals released from zinc oxide containing polymeric coated surface were spin trapped with DMPO (dimethylpyrroline-N-oxide spin trap and measured with Electron Spin Resonance (ESR. Besides conveyor belt samples, oxygen radical release from zinc oxide surface was measured with ESR under UV light and dark conditions. Oxygen radical release was determined even at dark conditions. Antibacterial properties were tested with ISO 22196 standard using Listeria innocua species. Measured antibacterial properties were related with ESR results. Higher concentration of zinc oxide resulted in higher antibacterial efficiency. DCFH-DA flourometric assay was carried out to determine oxidative stress insidebacteria. It is tought that, this technique will lead to decrease on the labour and time needed for conventional antibacterial tests.

  10. Magnetic field dependence of the lowest-frequency edge-localized spin wave mode in a magnetic nanotriangle.

    Science.gov (United States)

    Lin, C S; Lim, H S; Wang, Z K; Ng, S C; Kuok, M H; Adeyeye, A O

    2011-03-01

    An understanding of the spin dynamics of nanoscale magnetic elements is important for their applications in magnetic sensing and storage. Inhomogeneity of the demagnetizing field in a non-ellipsoidal magnetic element results in localization of spin waves near the edge of the element. However, relative little work has been carried out to investigate the effect of the applied magnetic fields on the nature of such localized modes. In this study, micromagnetic simulations are performed on an equilateral triangular nanomagnet to investigate the magnetic field dependence of the mode profiles of the lowest-frequency spin wave. Our findings reveal that the lowest-frequency mode is localized at the base edge of the equilateral triangle. The characteristics of its mode profile change with the ground state magnetization configuration of the nanotriangle, which, in turn, depends on the magnitude of the in-plane applied magnetic field.

  11. Floquet-Magnus expansion for general N-coupled spins systems in magic-angle spinning nuclear magnetic resonance spectra

    Science.gov (United States)

    Mananga, Eugene Stephane; Charpentier, Thibault

    2015-04-01

    In this paper we present a theoretical perturbative approach for describing the NMR spectrum of strongly dipolar-coupled spin systems under fast magic-angle spinning. Our treatment is based on two approaches: the Floquet approach and the Floquet-Magnus expansion. The Floquet approach is well known in the NMR community as a perturbative approach to get analytical approximations. Numerical procedures are based on step-by-step numerical integration of the corresponding differential equations. The Floquet-Magnus expansion is a perturbative approach of the Floquet theory. Furthermore, we address the " γ -encoding" effect using the Floquet-Magnus expansion approach. We show that the average over " γ " angle can be performed for any Hamiltonian with γ symmetry.

  12. Neural Network Model Of The PXIE RFQ Cooling System and Resonant Frequency Response

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, Auralee [Fermilab; Biedron, Sandra [Colorado State U., Fort Collins; Bowring, Daniel [Fermilab; Chase, Brian [Fermilab; Edelen, Jonathan [Fermilab; Milton, Stephen [Colorado State U., Fort Collins; Steimel, Jim [Fermilab

    2016-06-01

    As part of the PIP-II Injector Experiment (PXIE) accel-erator, a four-vane radio frequency quadrupole (RFQ) accelerates a 30-keV, 1-mA to 10-mA H' ion beam to 2.1 MeV. It is designed to operate at a frequency of 162.5 MHz with arbitrary duty factor, including continuous wave (CW) mode. The resonant frequency is controlled solely by a water-cooling system. We present an initial neural network model of the RFQ frequency response to changes in the cooling system and RF power conditions during pulsed operation. A neural network model will be used in a model predictive control scheme to regulate the resonant frequency of the RFQ.

  13. A small-form-factor piezoelectric vibration energy harvester using a resonant frequency-down conversion

    Directory of Open Access Journals (Sweden)

    Kyung Ho Sun

    2014-10-01

    Full Text Available While environmental vibrations are usually in the range of a few hundred Hertz, small-form-factor piezoelectric vibration energy harvesters will have higher resonant frequencies due to the structural size effect. To address this issue, we propose a resonant frequency-down conversion based on the theory of dynamic vibration absorber for the design of a small-form-factor piezoelectric vibration energy harvester. The proposed energy harvester consists of two frequency-tuned elastic components for lowering the first resonant frequency of an integrated system but is so configured that an energy harvesting beam component is inverted with respect to the other supporting beam component for a small form factor. Furthermore, in order to change the unwanted modal characteristic of small separation of resonant frequencies, as is the case with an inverted configuration, a proof mass on the supporting beam component is slightly shifted toward a second proof mass on the tip of the energy harvesting beam component. The proposed small-form-factor design capability was experimentally verified using a fabricated prototype with an occupation volume of 20 × 39 × 6.9 mm3, which was designed for a target frequency of as low as 100 Hz.

  14. A small-form-factor piezoelectric vibration energy harvester using a resonant frequency-down conversion

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Kyung Ho; Kim, Young-Cheol [Department of System Dynamics, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 305-343 (Korea, Republic of); Kim, Jae Eun, E-mail: jekim@cu.ac.kr [School of Mechanical and Automotive Engineering, Catholic University of Daegu, 13-13 Hayang-Ro, Hayang-Eup, Gyeongsan-Si, Gyeongsangbuk-Do 712-702 (Korea, Republic of)

    2014-10-15

    While environmental vibrations are usually in the range of a few hundred Hertz, small-form-factor piezoelectric vibration energy harvesters will have higher resonant frequencies due to the structural size effect. To address this issue, we propose a resonant frequency-down conversion based on the theory of dynamic vibration absorber for the design of a small-form-factor piezoelectric vibration energy harvester. The proposed energy harvester consists of two frequency-tuned elastic components for lowering the first resonant frequency of an integrated system but is so configured that an energy harvesting beam component is inverted with respect to the other supporting beam component for a small form factor. Furthermore, in order to change the unwanted modal characteristic of small separation of resonant frequencies, as is the case with an inverted configuration, a proof mass on the supporting beam component is slightly shifted toward a second proof mass on the tip of the energy harvesting beam component. The proposed small-form-factor design capability was experimentally verified using a fabricated prototype with an occupation volume of 20 × 39 × 6.9 mm{sup 3}, which was designed for a target frequency of as low as 100 Hz.

  15. Design of LCL-filters with LCL resonance frequencies beyond the Nyquist frequency for grid-connected inverters

    DEFF Research Database (Denmark)

    Tang, Yi; Yao, Wenli; Loh, Poh Chiang

    2015-01-01

    -switch based three-phase pulse-width modulated (PWM) converters. Moreover, a single-loop current control strategy is proposed for the designed LCL-filter, and the control system is inherently stable without introducing any passive or active damping. Experimental results, showing the high quality output......This paper proposes a novel LCL-filter design method and its current control for grid-connected converters. With the proposed design method, it is possible to set the resonance frequency of the LCL-filter to be higher than the Nyquist frequency, i.e. half of the system sampling frequency......, and this observation is so far not discussed in the literature. In this case, very cost-effective LCL-filter design can be achieved for grid-connected converters whose dominant switching harmonics may appear at double of the switching frequency, e.g. in unipolar modulated three-level full bridge converters and 12...

  16. Investigation of proton spin relaxation in water with dispersed silicon nanoparticles for potential magnetic resonance imaging applications

    Science.gov (United States)

    Kargina, Yu. V.; Gongalsky, M. B.; Perepukhov, A. M.; Gippius, A. A.; Minnekhanov, A. A.; Zvereva, E. A.; Maximychev, A. V.; Timoshenko, V. Yu.

    2018-03-01

    Porous and nonporous silicon (Si) nanoparticles (NPs) prepared by ball-milling of electrochemically etched porous Si layers and crystalline Si wafers were studied as potential agents for enhancement of the proton spin relaxation in aqueous media. While nonporous Si NPs did not significantly influence the spin relaxation, the porous ones resulted in strong shortening of the transverse relaxation times. In order to investigate an effect of the electron spin density in porous Si NPs on the proton spin relaxation, we use thermal annealing of the NPs in vacuum or in air. The transverse relaxation rate of about 0.5 l/(g s) was achieved for microporous Si NPs, which were thermally annealing in vacuum to obtain the electron spin density of the order of 1017 g-1. The transverse relaxation rate was found to be almost proportional to the concentration of porous Si NPs in the range from 0.1 to 20 g/l. The obtained results are discussed in view of possible biomedical applications of Si NPs as contrast agents for magnetic resonance imaging.

  17. Low-frequency permittivity of spin-density wave in (TMTSF)2PF6 at low temperatures

    DEFF Research Database (Denmark)

    Nad, F.; Monceau, P.; Bechgaard, K.

    1995-01-01

    Conductivity and permittivity epsilon of(TMTSF)(2)PF6 have been measured at low frequencies of (10(2)-10(7) Hz) at low temperatures below the spin-density wave (SDW) transition temperature T-p. The temperature dependence of the conductivity shows a deviation from thermally activated behavior at T...

  18. Impedance-Based High Frequency Resonance Analysis of DFIG System in Weak Grids

    OpenAIRE

    Song, Yipeng; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    The impedance-based model of Doubly Fed Induction Generator (DFIG) systems, including the rotor part (Rotor Side Converter (RSC) and induction machine), and the grid part (Grid Side Converter (GSC) and its output filter), has been developed for analysis and mitigation of the Sub- Synchronous Resonance (SSR). However, the High Frequency Resonance (HFR) of DFIG systems due to the impedance interaction between DFIG system and parallel compensated weak network is often overlooked. This paper thus...

  19. High Frequency Resonance Damping of DFIG based Wind Power System under Weak Network

    DEFF Research Database (Denmark)

    Song, Yipeng; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    When operating in a micro or weak grid which has a relatively large network impedance, the Doubly Fed Induction Generator (DFIG) based wind power generation system is prone to suffer high frequency resonance due to the impedance interaction between DFIG system and the parallel compensated network...... (series RL + shunt C). In order to improve the performance of the DFIG system as well as other units and loads connected to the weak grid, the high frequency resonance needs to be effectively damped. In this paper, the proposed active damping control strategy is able to implement effective damping either...... in the Rotor Side Converter (RSC) or in the Grid Side Converter (GSC), through the introduction of virtual positive capacitor or virtual negative inductor to reshape the DFIG system impedance and mitigate the high frequency resonance. A detailed theoretical explanation on the virtual positive capacitor...

  20. Non-contact excitation of fundamental resonance frequencies of an asphalt concrete specimen

    Science.gov (United States)

    Gudmarsson, Anders; Ryden, Nils; Birgisson, Björn

    2015-03-01

    Impact hammer and non-contact speaker excitation were applied to an asphalt concrete, a PVC-U and a concrete specimen to measure the fundamental longitudinal resonance frequency at different strain levels. The impact and the noncontact excitation methods resulted in similar resonance frequencies for the undamaged asphalt concrete and for the PVC-U specimen. However, the two excitation approaches gave different results for the concrete specimen, which was shown to have a nonlinear response to increasing strain levels. A reduction and a following recovery of the resonance frequency of the asphalt concrete were shown after the specimen was exposed to a small amount of damage. However, no fast nonlinear dynamics were observed for the asphalt concrete through the speaker measurements.

  1. Lithographed Superconducting Resonator Development for Next-Generation Frequency Multiplexing Readout of Transition-Edge Sensors

    Science.gov (United States)

    Faramarzi, F.; De Haan, T.; Kusaka, A.; Lee, A.; Neuhauser, B.; Plambeck, R.; Raum, C.; Suzuki, A.; Westbrook, B.

    2018-03-01

    Ground-based cosmic microwave background (CMB) experiments are undergoing a period of exponential growth. Current experiments are observing with 1000-10,000 detectors, and the next-generation experiment (CMB stage 4) is proposing to deploy approximately 500,000 detectors. This order of magnitude increase in detector count will require a new approach for readout electronics. We have developed superconducting resonators for next-generation frequency-domain multiplexing (fMUX) readout architecture. Our goal is to reduce the physical size of resonators, such that resonators and detectors can eventually be integrated on a single wafer. To reduce the size of these resonators, we have designed spiral inductors and interdigitated capacitors that resonate around 10-100 MHz, an order of magnitude higher frequency compared to current fMUX readout systems. The higher frequency leads to a wider bandwidth and would enable higher multiplexing factor than the current ˜ 50 detectors per readout channel. We will report on the simulation, fabrication method, characterization technique, and measurement of quality factor of these resonators.

  2. PREFACE: 13th International Conference on Muon Spin Rotation, Relaxation and Resonance

    Science.gov (United States)

    2014-12-01

    The 13th International Conference on Muon Spin Rotation, Relaxation and Resonance (μSR2014) organized by the Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute in collaboration with the University of Zurich and the University of Fribourg, was held in Grindelwald, Switzerland from 1st to 6th June 2014. The conference provided a forum for researchers from around the world with interests in the applications of μSR to study a wide range of topics including condensed matter physics, materials and molecular sciences, chemistry and biology. Polarized muons provide a unique and versatile probe of matter, enabling studies at the atomic level of electronic structure and dynamics in a wide range of systems. The conference was the thirteenth in a series, which began in Rorschach in 1978 and it took place for the third time in Switzerland. The previous conferences were held in Cancun, Mexico (2011), Tsukuba, Japan (2008), Oxford, UK (2005), Williamsburg, USA (2002), Les Diablerets, Switzerland (1999), Nikko, Japan (1996), Maui, USA (1993), Oxford, UK (1990), Uppsala, Sweden (1986), Shimoda, Japan (1983), Vancouver, Canada (1980), and Rorschach, Switzerland (1978). These conference proceedings contain 67 refereed publications from presentations covering magnetism, superconductivity, chemistry, semiconductors, biophysics and techniques. The conference logo, displayed in the front pages of these proceedings, represents both the location of μSR2014 in the Alps and the muon-spin rotation technique. The silhouette represents the famous local mountains Eiger, Mönch and Jungfrau as drawn by the Swiss painter Ferdinand Hodler and the apple with arrow is at the same time a citation of the Wilhelm Tell legend and a remembrance of the key role played by the muon spin and the asymmetric muon decay (which for the highest positron energy has an apple like shape). More than 160 participants (including 32 registered as students and 13 as accompanying persons) from 19 countries

  3. All-solid-state continuous-wave doubly resonant all-intracavity sum-frequency mixer.

    Science.gov (United States)

    Kretschmann, H M; Heine, F; Huber, G; Halldórsson, T

    1997-10-01

    A new resonator design for doubly resonant continuous-wave intracavity sum-frequency mixing is presented. We generated 212 mW of coherent radiation at 618 nm by mixing the radiation of a 1080-nm Nd(3+):YAlO(3) laser and a 1444-nm Nd(3+):YAG laser. Two different mixing resonator setups and several nonlinear-optical crystals were investigated. So far output is limited by unequal performance of the two fundamental lasers and coating problems of the nonlinear crystals.

  4. Acquisition of 3D temperature distributions in fluid flow using proton resonance frequency thermometry.

    Science.gov (United States)

    Buchenberg, Waltraud B; Wassermann, Florian; Grundmann, Sven; Jung, Bernd; Simpson, Robin

    2016-07-01

    Proton resonance frequency thermometry is well established for monitoring small temperature changes in tissue. Application of the technique to the measurement of complex temperature distributions within fluid flow is of great interest to the engineering community and could also have medical applications. This work presents an experimental approach to reliably measure three-dimensional (3D) temperature fields in fluid flow using proton resonance frequency thermometry. A velocity-compensated three-dimensional gradient echo sequence was used. A flexible pumping system was attached to an MR compatible double pipe heat exchanger. The temperature of two separate flow circuits could be adjusted to produce various three-dimensional spatial temperature distributions within the fluid flow. Validation was performed using MR compatible temperature probes in a uniformly heated flow. A comparative study was conducted with thermocouples in the presence of a spatially varying temperature distribution. In uniformly heated flow, temperature changes were accurately measured to within 0.5 K using proton resonance frequency thermometry, while spatially varying temperature changes measured with MR showed good qualitative agreement with pointwise measurements using thermocouples. Proton resonance frequency thermometry can be used in a variety of complex flow situations to address medical as well as engineering questions. This work makes it possible to gain new insights into fundamental heat transfer phenomena. Magn Reson Med 76:145-155, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  5. Zero-group-velocity acoustic waveguides for high-frequency resonators

    Science.gov (United States)

    Caliendo, C.; Hamidullah, M.

    2017-11-01

    The propagation of the Lamb-like modes along a silicon-on-insulator (SOI)/AlN thin supported structure was simulated in order to exploit the intrinsic zero group velocity (ZGV) features to design electroacoustic resonators that do not require metal strip gratings or suspended edges to confine the acoustic energy. The ZGV resonant conditions in the SOI/AlN composite plate, i.e. the frequencies where the mode group velocity vanishes while the phase velocity remains finite, were investigated in the frequency range from few hundreds of MHz up to 1900 MHz. Some ZGV points were found that show up mostly in low-order modes. The thermal behaviour of these points was studied in the  ‑30 to 220 °C temperature range and the temperature coefficients of the ZGV resonant frequencies (TCF) were estimated. The behaviour of the ZGV resonators operating as gas sensors was studied under the hypothesis that the surface of the device is covered with a thin polyisobutylene (PIB) film able to selectively adsorb dichloromethane (CH2Cl2), trichloromethane (CHCl3), carbontetrachloride (CCl4), tetrachloroethylene (C2Cl4), and trichloroethylene (C2HCl3), at atmospheric pressure and room temperature. The sensor sensitivity to gas concentration in air was simulated for the first four ZGV points of the inhomogeneous plate. The feasibility of high-frequency, low TCF electroacoustic micro-resonator based on SOI and piezoelectric thin film technology was demonstrated by the present simulation study.

  6. Measurements of frequency fluctuations in aluminum nitride contour-mode resonators.

    Science.gov (United States)

    Miller, Nicholas; Piazza, Gianluca

    2014-06-01

    As part of the current drive to engineer miniaturized monolithic high-performance microelectromechanical-enabled oscillators, there is a need for further study of frequency fluctuations in microelectromechanical resonators. To this end, we present the measurement of frequency fluctuations for 128 aluminum nitride contour-mode resonators. The measurements show that fluctuations are sufficiently large to play an important role in oscillator performance. These results were obtained for the first time from vector network analyzer measurements and are accompanied by an analysis of the experimental setup.

  7. Electrical tuning and switching of an optical frequency comb generated in aluminum nitride microring resonators.

    Science.gov (United States)

    Jung, Hojoong; Fong, King Y; Xiong, Chi; Tang, Hong X

    2014-01-01

    Aluminum nitride (AlN) has been shown to possess both strong Kerr nonlinearity and electro-optic Pockels effect. By combining these two effects, here we demonstrate on-chip reversible on/off switching of the optical frequency comb generated by an AlN microring resonator. We optimize the design of gating electrodes and the underneath resonator structure to effectively apply an electric field without increasing the optical loss. The switching of the comb is monitored by measuring one of the frequency comb peaks while varying the electric field. The controlled comb electro-optic response is investigated for direct comparison with the transient thermal effect.

  8. Analysis of the Behavior of Undamped and Unstable High-Frequency Resonance in DFIG System

    DEFF Research Database (Denmark)

    Song, Yipeng; Blaabjerg, Frede

    2017-01-01

    As the wind power generation develops, the Doubly Fed Induction Generator (DFIG) based wind power system may suffer Sub Synchronous Resonance (SSR) and High Frequency Resonance (HFR) in the series and parallel compensated weak network. The principle and frequency of HFR have been discussed using...... the Bode diagram as an analysis tool. However, the HFR can be categorized into two different types: undamped HFR (which exists in steady state) and unstable HFR (which eventually results in complete instability and divergence), both of them are not investigated before. Since both the undamped HFR...

  9. Mercury's capture into the 3/2 spin-orbit resonance as a result of its chaotic dynamics.

    Science.gov (United States)

    Correia, Alexandre C M; Laskar, Jacques

    2004-06-24

    Mercury is locked into a 3/2 spin-orbit resonance where it rotates three times on its axis for every two orbits around the sun. The stability of this equilibrium state is well established, but our understanding of how this state initially arose remains unsatisfactory. Unless one uses an unrealistic tidal model with constant torques (which cannot account for the observed damping of the libration of the planet) the computed probability of capture into 3/2 resonance is very low (about 7 per cent). This led to the proposal that core-mantle friction may have increased the capture probability, but such a process requires very specific values of the core viscosity. Here we show that the chaotic evolution of Mercury's orbit can drive its eccentricity beyond 0.325 during the planet's history, which very efficiently leads to its capture into the 3/2 resonance. In our numerical integrations of 1,000 orbits of Mercury over 4 Gyr, capture into the 3/2 spin-orbit resonant state was the most probable final outcome of the planet's evolution, occurring 55.4 per cent of the time.

  10. Statistical analysis of nature frequencies of hemispherical resonator gyroscope based on probability theory

    Science.gov (United States)

    Yu, Xudong; Long, Xingwu; Wei, Guo; Li, Geng; Qu, Tianliang

    2015-04-01

    A finite element model of the hemispherical resonator gyro (HRG) is established and the natural frequencies and vibration modes are investigated. The matrix perturbation technology in the random finite element method is first introduced to analyze the statistical characteristics of the natural frequencies of HRG. The influences of random material parameters and dimensional parameters on the natural frequencies are quantitatively described based on the probability theory. The statistics expressions of the random parameters are given and the influences of three key parameters on natural frequency are pointed out. These results are important for design and improvement of high accuracy HRG.

  11. Electron spin resonance investigaton of semiconductor materials for application in thin-film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Lihong

    2012-07-01

    In the present work, hydrogenated silicon and its alloys silicon carbide and silicon oxide have been investigated using electron spin resonance (ESR). The microstructure of these materials ranges from highly crystalline to amorphous. The correlation between the paramagnetic defects, microstructure, optical and electrical properties has been discussed. Correspondingly, these properties were characterized by the spin density (N{sub S}), g-value and the lineshape of ESR spectra, Infrared (I{sup IR}{sub C}) and/or Raman crystallinity (I{sup RS}{sub C}) as well as optical absorption and electrical dark conductivity ({sigma}{sub D}). 1. As the light absorber, Si layers essentially should have low defect density and good stability against light exposure. The spin density (N{sub S}) measured by ESR is often used as a measure for the paramagnetic defect density (N{sub D}) in the material. However, ESR sample preparation procedures can potentially cause discrepancy between N{sub S} and N{sub D}. Using Mo-foil, Al-foil and ZnO:Al-covered glass as sacrificial substrates, {mu}c-Si:H and a-Si:H films were deposited by plasma-enhanced chemical vapor deposition (PECVD), and ESR powder samples have been prepared with corresponding procedures. Possible preparation-related metastability and instability effects have been investigated in terms of substrate dependence, HCl-etching and atmosphere exposure. A sequence of 'preparation - annealing - air-exposure - annealing' has been designed to investigate the metastability and instability effects. N{sub S} after post-preparation air exposure is higher than in the annealed states, especially for the highly crystalline {mu}c-Si:H material the discrepancy reached one order of magnitude. Low temperature ESR measurements at 40 K indicated that atmospheric exposure leads to a redistribution of the defect states which in turn influence the evaluated N{sub S}. In annealed conditions the samples tend to have lower N{sub S} presumably due

  12. Schumann resonance frequency variations observed in magnetotelluric data recorded from Garhwal Himalayan region India

    Directory of Open Access Journals (Sweden)

    R. Chand

    2009-09-01

    Full Text Available Schumann resonance (SR frequency variation has been studied using Magnetotelluric (MT data recorded in one of the world's toughest and generally inaccessible Himalayan terrain for the first time in the author's knowledge. The magnetotelluric data, in the form of orthogonal time varying electric and magnetic field components (Ex, Ey, Bx and By, recorded during 10 March–23 May 2006, in the Himalayan region, India, at elevations between 1228–2747 m above mean sea level (amsl, were used to study the SR frequency variation. Electromagnetic field components, in the form of time series, were recorded at 64 Hz sampling frequency at a site located away from the cultural noise. Spectral analysis of time series data, at a frequency resolution of 0.03 Hz, has been performed using Fast Fourier Transform (FFT algorithm. Spectral stabilization in three Schumann resonance modes is achieved by averaging the power spectral magnitude of 32 data segments, each with 2048 sample data. Amplitude variation in the Schumann resonance frequency associated with day-night, sunrise and terminator effect was observed. Average diurnal variation in the first three Schumann resonance frequencies associated with magnetic field components is presented. The maximum frequency variation of about 0.3, 0.4 and 0.7 Hz was observed in the first, second and third mode, respectively. The frequency variations observed in electric and magnetic field components also show phase shift and varying attenuation. The SR frequency variation has been used to define the ionospheric electron density variation in the Himalayan region, India.

  13. Schumann resonance frequency variations observed in magnetotelluric data recorded from Garhwal Himalayan region India

    Directory of Open Access Journals (Sweden)

    R. Chand

    2009-09-01

    Full Text Available Schumann resonance (SR frequency variation has been studied using Magnetotelluric (MT data recorded in one of the world's toughest and generally inaccessible Himalayan terrain for the first time in the author's knowledge. The magnetotelluric data, in the form of orthogonal time varying electric and magnetic field components (Ex, Ey, Bx and By, recorded during 10 March–23 May 2006, in the Himalayan region, India, at elevations between 1228–2747 m above mean sea level (amsl, were used to study the SR frequency variation. Electromagnetic field components, in the form of time series, were recorded at 64 Hz sampling frequency at a site located away from the cultural noise. Spectral analysis of time series data, at a frequency resolution of 0.03 Hz, has been performed using Fast Fourier Transform (FFT algorithm. Spectral stabilization in three Schumann resonance modes is achieved by averaging the power spectral magnitude of 32 data segments, each with 2048 sample data. Amplitude variation in the Schumann resonance frequency associated with day-night, sunrise and terminator effect was observed. Average diurnal variation in the first three Schumann resonance frequencies associated with magnetic field components is presented. The maximum frequency variation of about 0.3, 0.4 and 0.7 Hz was observed in the first, second and third mode, respectively. The frequency variations observed in electric and magnetic field components also show phase shift and varying attenuation. The SR frequency variation has been used to define the ionospheric electron density variation in the Himalayan region, India.

  14. Resolution adapted finite element modeling of radio frequency interactions on conductive resonant structures in MRI.

    Science.gov (United States)

    Ruoff, Jürgen; Würslin, Christian; Graf, Hansjörg; Schick, Fritz

    2012-05-01

    Prediction of interactions between the radiofrequency electromagnetic field in magnetic resonance scanners and electrically conductive material surrounded by tissue plays an increasing role for magnetic resonance safety. Testing of conductive implants or instruments is usually performed by standardized experimental setups and temperature measurements at distinct geometrical points, which cannot always reflect worst-case situations. A finite element method based on Matlab (The Mathworks, Natick, MA) and the finite element method program Comsol Multiphysics (Stockholm, Sweden) with a spatially highly variable mesh size solving Maxwell's full-wave equations was applied for a comprehensive simulation of the complete geometrical arrangement of typical birdcage radiofrequency coils loaded with small conductive structures in a homogenous medium. Conductive implants like rods of variable length and closed and open ring structures, partly exhibiting electromagnetic resonance behavior, were modeled and evaluated regarding the distribution of the B(1)- and E-field, induced currents and specific absorption rates. Numerical simulations corresponded well with experiments using a spin-echo sequence for visualization of marked B(1)-field inhomogeneities. Even resonance effects in conductive rods and open rings with suitable geometry were depicted accurately. The proposed method has high potential for complementation or even replacement of common experimental magnetic resonance compatibility measurements. Copyright © 2011 Wiley Periodicals, Inc.

  15. Changes in mitochondrial functioning with electromagnetic radiation of ultra high frequency as revealed by electron paramagnetic resonance methods.

    Science.gov (United States)

    Burlaka, Anatoly; Selyuk, Marina; Gafurov, Marat; Lukin, Sergei; Potaskalova, Viktoria; Sidorik, Evgeny

    2014-05-01

    To study the effects of electromagnetic radiation (EMR) of ultra high frequency (UHF) in the doses equivalent to the maximal permitted energy load for the staffs of the radar stations on the biochemical processes that occur in the cell organelles. Liver, cardiac and aorta tissues from the male rats exposed to non-thermal UHF EMR in pulsed and continuous modes were studied during 28 days after the irradiation by the electron paramagnetic resonance (EPR) methods including a spin trapping of superoxide radicals. The qualitative and quantitative disturbances in electron transport chain (ETC) of mitochondria are registered. A formation of the iron-nitrosyl complexes of nitric oxide (NO) radicals with the iron-sulphide (FeS) proteins, the decreased activity of FeS-protein N2 of NADH-ubiquinone oxidoreductase complex and flavo-ubisemiquinone growth combined with the increased rates of superoxide production are obtained. (i) Abnormalities in the mitochondrial ETC of liver and aorta cells are more pronounced for animals radiated in a pulsed mode; (ii) the alterations in the functioning of the mitochondrial ETC cause increase of superoxide radicals generation rate in all samples, formation of cellular hypoxia, and intensification of the oxide-initiated metabolic changes; and (iii) electron paramagnetic resonance methods could be used to track the qualitative and quantitative changes in the mitochondrial ETC caused by the UHF EMR.

  16. EPR Studies of Spin Labels Bound to Ceramic Surfaces, and Simulation of Magnetic Resonance Spectra by Molecular Trajectory.

    Science.gov (United States)

    Auteri, Francesco Paul

    Electron paramagnetic resonance (EPR) spectroscopy is sensitive to molecular rotational correlation times in the range of 10^{-6} to 10^{-11} seconds. EPR spin labels are often attached or incorporated into molecular structures as probes of local viscosities and dynamics. In part I of this work, methods of covalently attaching a variety of spin labels to silica and alumina ceramic surfaces are developed in an attempt to study local viscosities at varying distances from about 5 A^circ to 25 A^circ from the ceramic/liquid interface. Three solvents, diethyl ether, benzene, and cyclohexane, are chosen for detailed study in combination with the spin labels, TEMPOL, 5-DOXYL, and 12-DOXYL. EPR spectra of each system are taken over the range of temperatures from -140 ^circC to 50^circ C (or just below the solvent boiling point). Spectra show good sensitivity to solvent, temperature, and probe. The effect of adding 3% (w/o) poly-(octadecyl-methacrylate) (PODM) to benzene and cyclohexane on spin label mobility is also studied in this work. Rotational correlation times from lineshapes are analyzed assuming isotropic rotation using spectral splitting, line width, and simulation methods. These approaches are often inadequate for the more complex spectral line shapes observed for tethered spin labels, especially in the intermediate motional regime where sensitivity to anisotropic dynamics is greatest. In part II of this work, a novel approach to the prediction of spectral line shapes is developed. It is shown that EPR spectra may be computed directly from molecular trajectories using classical approximations to describe the time evolution of the magnetization vector under fluctuating effective interaction tensor values. Line shape simulations using molecular trajectories generated by Brownian dynamics theory are less time intensive than existing methods. Simulation of magnetic resonance line shapes by molecular trajectories as generated by programs such as CHARMM promises to be

  17. Electron Spin Resonance studies of defects formed in SiO2 by high energy ions

    International Nuclear Information System (INIS)

    Dooryhee, Eric

    1987-01-01

    We have studied the defects formed in silica by high energy ions. Defect formation processes are not yet well understood at energies higher than 1 MeV/amu, whereas they can be interpreted in terms of collision cascades at low energies. There are numerous applications in astrophysics (cosmic rays), earth sciences (fission track dating), and for technological problems (storage of radioactive waste material, fusion reactors). We have used Electron Spin Resonance (ESR) together with other techniques (optical spectroscopy, channeling, small angle X-ray scattering) to characterize defects formed by electronic excitations and to study the influence of the energy, the atomic number and the fluence of ions. We have irradiated silica and alumina targets at GANIL and at UNILAC Darmstadt. ESR studies have shown that high energy ions form paramagnetic vacancies (E' centers) and interstitials (peroxy radicals). Their ESR signatures exhibit specific characteristics when compared to those observed after gamma-ray or electron irradiation, which can be related to the very high density of deposited energy, and to the specific environment within clusters of defects. The production rate of defects varies with the atomic number of the incident ion, for a given energy deposit. The proportion of peroxy radicals increases with stopping power. When fluence increases above the overlapping threshold, a transfer from E' centers to peroxy radicals is observed, similar to that observed after thermal annealing. These results demonstrate the nonlinear effects of energy losses and the role of a phase in which primary defects reorganize in the wake of the incident ion ('thermal spike' concept). Optical spectroscopy experiments allowed us to show that high energy ions also form diamagnetic oxygen vacancies. However, the total defect concentration observed is too low to account for the preferential chemical etching of ion tracks. Local bond straining induced by the ion could

  18. Simultaneous electrochemical-electron spin resonance studies of carotenoid cation radicals and dications

    International Nuclear Information System (INIS)

    Khaled, M.; Hadjipetrou, A.; Xinhai Chen; Kispert, L.

    1989-01-01

    Carotenoids are present in the chloroplasts of photosynthetic green plants and serve as photoprotect devices and antenna pigments, and active role in the photosynthetic electron-transport chain with the carotenoid cation radical as an integral part of the electron-transfer process. The research reported herein has confirmed that carotenoid cation radicals have a lifetime that is sensitive to solvent, being longest in CH 2 Cl 2 and are best prepared electrochemically. Semiempirical AM1 and INDO calculations of the trans and cis isomers of β-carotene, canthaxanthin and β-apo-8'-carotenal cation radicals predicted the unresolved EPR line whose linewidth varies to a measurable degree with carotenoid, which subsequent experimental observations affirmed. Simultaneous electrochemical - electron spin resonance studies of carotenoid cation radicals and dications have shown the radicals detected by EPR are formed by the one electron oxidation of the carotenoid, that dimers are not formed upon decay of the radical cations and an estimate of the rate of comproportionation as a function of carotenoid can be given. The formal rate constant K' for heterogenous electron transfer rate at the electrode surface has been deduced from rotating disc experiments. Upon deuteration, and in the presence of excess β-carotene, the half-life for decay of the carotenoid radical cation increased an order of magnitude due to the reaction between diffusion carotenoid dications and carotenoids to form additional radical cations. The carotenoid diffusion coefficients deduced by chronocoulometry substantiates this measurement. The produces formed upon electrochemical studies are being studied by HPLC and the isomers formed thermally are being separated. Additional radical reactions are currently being studied by EPR and electrochemical methods

  19. Applications of electron spin resonance to some problems of radiation chemistry

    International Nuclear Information System (INIS)

    Chachaty, C.

    1969-01-01

    The electron spin resonance (E.S.R.) spectra of gamma irradiated polar organic glasses, at 77 K, shows a single line centered at g ∼ 2, attributed to solvated electrons. The radicals produced on scavenging this species by electron acceptors, such as aromatic hydrocarbons, nitro-compounds and azines have been studied by E.S.R. In most cases, the radicals from these solutes, the spectra of which are observed after elimination by warming of the radicals from the matrices, are produced by protonation of the anions formed by scavenging of electrons at 77 K. Thus, in the case of glassy solutions of nitro-compounds, the radicals R NO 2 H are formed. They are characterized by a N = 15 G (nitrobenzene) or a N = 28 G (nitro-alkane). These radicals are also generated by U.V, photolysis at room temperature of solutions of nitro-compounds in alcohols and are shown to be the precursors of nitroxide radicals R - N - R (with N - O) observed simultaneously. Gamma irradiation of solutions of pyridine and of the three diazines, in alcohol glasses at 77 K, produces the radical formed by hydrogen addition to these compounds. The value of the coupling constant of the additional proton (7-10 G) indicates that it is bound to a nitrogen in the sp 2 hydridation state. One has shown, taking pyridine as an example, that the addition to a carbon gives a much greater value of the coupling constant, of the order of 50-60 G. (author) [fr

  20. Study by electron spin resonance (ESR) of 60 Co irradiated grains and farinaceous derivatives

    International Nuclear Information System (INIS)

    Catanni, Marta Mattos.

    1995-01-01

    The electron spin resonance (ESR) spectroscopy is being pointed out as one of the most promising techniques to determine whether a food has been irradiated. In this work, the ESR spectrum of paramagnetic radicals produced by gamma irradiation of grains and flour derivatives using a 60 Co source was investigated. Samples of grains (wheat and barley), flours (wheat, maniac, rye, soy bean and maize), bran and starch have been irradiated with doses between 0.2 and 70 KGy. It was shown that all varieties of grains and flours presented similar ESR spectra with variation in the free radicals signal intensity. Measurements at 9.5 and 34.5 GHz shown that spectra were composed probably by the superposition of four paramagnetic species with g-factors closed to that of the free electron (2 triplets, 1 doublet and 1 singlet). Hyperfine interactions and the correspondingly line widths were estimated through an spectrum computer simulation. It was established that ESR signal intensities increased with the irradiation dose for all samples. Up to the commercial admissible dose limit (1 kGy), the increase of ESR signal shown a linear behavior with the dose. The signal stability varied significantly with storage conditions and sample humidity. For 1 kGy-irradiated samples stored at room temperature and 14% humidity, the ESR radiation signals were possible to be detected up to 5 days after irradiation. When the same samples were stored at low temperatures (0 0 C) or freeze-dried (almost 0% humidity) the ESR signals were detected until 6 months after irradiation. Similar ESR spectrum found for grains and flours was obtained for diverse starchy food products. It was verified that it is possible to identify for a long time irradiated starchy foods when they are commercialized dehydrated or frozen. (author). 66 refs., 35 figs., 17 tabs

  1. Electron spin resonance and thermoluminescence in powder form of clear fused quartz: effects of grinding

    International Nuclear Information System (INIS)

    Ranjbar, A.H.; Durrani, S.A.; Randle, K.

    1999-01-01

    Clear fused quartz (CFQ) tubes were powdered either manually by using a mortar and pestle (for coarse production) or mechanically, using a micronising mill (for fine production). A high and multisignal electron spin resonance (ESR) background was found in the fine powder even after annealing it at 900 deg. C for 20 min. In the case of the coarse powder, the signal (ESR background) varied inversely with particle size and was quite high for particle sizes lower than 38 μm. In a subsidiary experiment, using fine SiO 2 powder (99.8% pure, with the particle size of ∼0.007 μm), manufactured by using flame hydrolysis, only a weak background signal was found. The 60 Co gamma-ray irradiated powders (∼22 Gy) were subjected to ESR analysis or thermoluminescence (TL) readout. The ESR intensity of the coarse powder varied directly with particle size. Thus, the intensity for a particle size of 20-38 μm was very low and almost the same as the unirradiated intensity. In TL readout the results were the opposite: the TL intensity of the coarse powder varied inversely with the particle size down to 38 μm, after which it decreased with decreasing particle size of the material. The fine powder, produced by grinding the CFQ tubes, was insensitive to gamma-rays (at least at doses of up to 50 Gy); but for the flame hydrolysis SiO 2 the situation was the opposite. The minimum detectable dose (MDD) for the CFQ in powder form using ESR was ∼2 Gy, which is ∼2 times higher than that for the bulk form, while the MDD for the powder using TL was ∼20 μGy, which is ∼2 times lower than that for the bulk form of the material

  2. Analysis of Glass-Reinforced Epoxy Material for Radio Frequency Resonator

    Directory of Open Access Journals (Sweden)

    M. R. Zaman

    2014-01-01

    Full Text Available A radio frequency (RF resonator using glass-reinforced epoxy material for C and X band is proposed in this paper. Microstrip line technology for RF over glass-reinforced epoxy material is analyzed. Coupling mechanism over RF material and parasitic coupling performance is explained utilizing even and odd mode impedance with relevant equivalent circuit. Babinet’s principle is deployed to explicate the circular slot ground plane of the proposed resonator. The resonator is designed over four materials from different backgrounds which are glass-reinforced epoxy, polyester, gallium arsenide (GaAs, and rogers RO 4350B. Parametric studies and optimization algorithm are applied over the geometry of the microstrip resonator to achieve dual band response for C and X band. Resonator behaviors for different materials are concluded and compared for the same structure. The final design is fabricated over glass-reinforced epoxy material. The fabricated resonator shows a maximum directivity of 5.65 dBi and 6.62 dBi at 5.84 GHz and 8.16 GHz, respectively. The lowest resonance response is less than −20 dB for C band and −34 dB for X band. The resonator is prototyped using LPKF (S63 drilling machine to study the material behavior.

  3. Self-frequency doubling in a laser-active whispering-gallery resonator.

    Science.gov (United States)

    Herr, Simon J; Folwill, Yannick; Buse, Karsten; Breunig, Ingo

    2017-07-01

    Lasing and self-frequency doubling are achieved in a millimeter-sized laser-active whispering-gallery resonator made of neodymium-doped lithium niobate. A low-cost 808-nm laser diode without external frequency stabilization is sufficient to pump the neodymium ions. Laser oscillation around 1.08 μm drives a frequency-doubling process within the same cavity providing green light. The electrical-optical efficiency of the system reaches up to 2×10 -4 . To the best of our knowledge, this is the first demonstration of combining lasing and χ (2) frequency conversion in a single high-Q whispering-gallery resonator. This approach is general and can be applied to other materials and other nonlinear optical processes.

  4. Optical frequency comb generation from aluminum nitride micro-ring resonator

    OpenAIRE

    Jung, Hojoong; Xiong, Chi; Fong, King Y.; Zhang, Xufeng; Tang, Hong X.

    2013-01-01

    Aluminum nitride is an appealing nonlinear optical material for on-chip wavelength conversion. Here we report optical frequency comb generation from high quality factor aluminum nitride micro-ring resonators integrated on silicon substrates. By engineering the waveguide structure to achieve near-zero dispersion at telecommunication wavelengths and optimizing the phase matching for four-wave mixing, frequency combs are generated with a single wavelength continuous-wave pump laser. The Kerr coe...

  5. ISQ calculation evaluation of in vitro laser scanning vibrometry-captured resonance frequency.

    Science.gov (United States)

    Debruyne, Stijn; Grognard, Nicolas; Verleye, Gino; Van Massenhove, Korneel; Mavreas, Dimitrios; Vannet, Bart Vande

    2017-10-12

    Implant stability testing at various stages of implant therapy by means of resonance frequency analysis is extensively used. The overall measurement outcome is a function of the resulting stiffness of three entities: surrounding bone, bone-implant complex, and implant-Smartpeg complex. The influence of the latter on the overall measurement results is presently unknown. It can be investigated in vitro by use of imbedded implants with mounted Smartpegs. This enables to keep the influence of the two other entities constant and controlled. The purpose of this study is to verify if a laboratory laser Doppler vibrometry technology-based procedure results in comparable ISQ results after calculation of captured resonance frequency spectra by aid of the Osstell algorithm with direct Osstell IDX device measurements. A laboratory procedure was engineered to record frequency spectra of resin-imbedded test implants with mounted Smartpegs, after electromagnetic excitation with the Osstell IDX device and laser Doppler vibrometry response detection. Fast Fourier transformation data processing of resonance frequency data resulted in determination of a maximum resonance frequency values allowing calculation of implant stability quotient (ISQ) values using the Osstell algorithm. Laboratory-based ISQ values were compared to Osstell IDx device-generated ISQ values for Straumann tissue level, Ankylos, and 3i Certain implant systems. For both systems, a correlation coefficient r = 0.99 was found. Furthermore, a clinically rejectable mean difference of 0.09 ISQ units was noted between both datasets. The proposed laboratory method with the application of the Osstell algorithm for ISQ calculation is appropriate for future studies to in vitro research aspects of resonance frequency analysis implant stability measurements.

  6. Monolithically integrated tri-axis shock accelerometers with MHz-level high resonant-frequency

    Science.gov (United States)

    Zou, Hongshuo; Wang, Jiachou; Chen, Fang; Bao, Haifei; Jiao, Ding; Zhang, Kun; Song, Zhaohui; Li, Xinxin

    2017-07-01

    This paper reports a novel monolithically integrated tri-axis high-shock accelerometer with high resonant-frequency for the detection of a broad frequency-band shock signal. For the first time, a resonant-frequency as high as about 1.4 MHz is designed for all the x-, y- and z-axis accelerometers of the integrated tri-axis sensor. In order to achieve a wide frequency-band detection performance, all the three sensing structures are designed into an axially compressed/stretched tiny-beam sensing scheme, where the p  +  -doped tiny-beams are connected into a Wheatstone bridge for piezoresistive output. By using ordinary (1 1 1) silicon wafer (i.e. non-SOI wafer), a single-wafer based fabrication technique is developed to monolithically integrate the three sensing structures for the tri-axis sensor. Testing results under high-shock acceleration show that each of the integrated three-axis accelerometers exhibit about 1.4 MHz resonant-frequency and 0.2-0.4 µV/V/g sensitivity. The achieved high frequencies for all the three sensing units make the tri-axis sensor promising in high fidelity 3D high-shock detection applications.

  7. Chasing the thermodynamical noise limit in whispering-gallery-mode resonators for ultrastable laser frequency stabilization.

    Science.gov (United States)

    Lim, Jinkang; Savchenkov, Anatoliy A; Dale, Elijah; Liang, Wei; Eliyahu, Danny; Ilchenko, Vladimir; Matsko, Andrey B; Maleki, Lute; Wong, Chee Wei

    2017-03-31

    Ultrastable high-spectral-purity lasers have served as the cornerstone behind optical atomic clocks, quantum measurements, precision optical microwave generation, high-resolution optical spectroscopy, and sensing. Hertz-level lasers stabilized to high-finesse Fabry-Pérot cavities are typically used for these studies, which are large and fragile and remain laboratory instruments. There is a clear demand for rugged miniaturized lasers with stabilities comparable to those of bulk lasers. Over the past decade, ultrahigh-Q optical whispering-gallery-mode resonators have served as a platform for low-noise microlasers but have not yet reached the stabilities defined by their fundamental noise. Here, we show the noise characteristics of whispering-gallery-mode resonators and demonstrate a resonator-stabilized laser at this limit by compensating the intrinsic thermal expansion, allowing a sub-25 Hz linewidth and a 32 Hz Allan deviation. We also reveal the environmental sensitivities of the resonator at the thermodynamical noise limit and long-term frequency drifts governed by random-walk-noise statistics.High-quality optical resonators have the potential to provide a miniaturized frequency reference for metrology and sensing but they often lack stability. Here, Lim et al. experimentally characterize the stability of whispering-gallery resonators at their fundamental noise limits.

  8. Snake resonances

    International Nuclear Information System (INIS)

    Tepikian, S.

    1989-01-01

    Siberian Snakes provide a practical means of obtaining polarized proton beams in large accelerators. The effect of snakes can be understood by studying the dynamics of spin precession in an accelerator with snakes and a single spin resonance. This leads to a new class of energy independent spin depolarizing resonances, called snake resonances. In designing a large accelerator with snakes to preserve the spin polarization, there is an added constraint on the choice of the vertical betatron tune due to the snake resonances

  9. Multinuclear solid-state high-resolution and C-13 -{Al-27} double-resonance magic-angle spinning NMR studies on aluminum alkoxides

    NARCIS (Netherlands)

    Abraham, A.; Prins, R.; Bokhoven, J.A. van; Eck, E.R.H. van; Kentgens, A.P.M.

    2006-01-01

    A combination of Al-27 magic-angle spinning (MAS)/multiple quantum (MQ)-MAS, C-13-H-1 CPMAS, and C-13-{Al-27} transfer of population in double-resonance (TRAPDOR) nuclear magnetic resonance (NMR) were used for the structural elucidation of the aluminum alkoxides aluminum ethoxide, aluminum

  10. Dynamic pressure probe response tests for robust measurements in periodic flows close to probe resonating frequency

    Science.gov (United States)

    Ceyhun Şahin, Fatma; Schiffmann, Jürg

    2018-02-01

    A single-hole probe was designed to measure steady and periodic flows with high fluctuation amplitudes and with minimal flow intrusion. Because of its high aspect ratio, estimations showed that the probe resonates at a frequency two orders of magnitude lower than the fast response sensor cut-off frequencies. The high fluctuation amplitudes cause a non-linear behavior of the probe and available models are neither adequate for a quantitative estimation of the resonating frequencies nor for predicting the system damping. Instead, a non-linear data correction procedure based on individual transfer functions defined for each harmonic contribution is introduced for pneumatic probes that allows to extend their operating range beyond the resonating frequencies and linear dynamics. This data correction procedure was assessed on a miniature single-hole probe of 0.35 mm inner diameter which was designed to measure flow speed and direction. For the reliable use of such a probe in periodic flows, its frequency response was reproduced with a siren disk, which allows exciting the probe up to 10 kHz with peak-to-peak amplitudes ranging between 20%-170% of the absolute mean pressure. The effect of the probe interior design on the phase lag and amplitude distortion in periodic flow measurements was investigated on probes with similar inner diameters and different lengths or similar aspect ratios (L/D) and different total interior volumes. The results suggest that while the tube length consistently sets the resonance frequency, the internal total volume affects the non-linear dynamic response in terms of varying gain functions. A detailed analysis of the introduced calibration methodology shows that the goodness of the reconstructed data compared to the reference data is above 75% for fundamental frequencies up to twice the probe resonance frequency. The results clearly suggest that the introduced procedure is adequate to capture non-linear pneumatic probe dynamics and to

  11. Optical fiber strain sensor using fiber resonator based on frequency comb Vernier spectroscopy

    DEFF Research Database (Denmark)

    Zhang, Liang; Lu, Ping; Chen, Li

    2012-01-01

    A novel (to our best knowledge) optical fiber strain sensor using a fiber ring resonator based on frequency comb Vernier spectroscopy is proposed and demonstrated. A passively mode-locked optical fiber laser is employed to generate a phased-locked frequency comb. Strain applied to the optical fiber...... be proportionally improved by increasing the length of the optical fiber ring resonator....... of the fiber ring resonator can be measured with the transmission spectrum. A good linearity is obtained between displacement and the inverse of wavelength spacing with an R2 of 0.9989, and high sensitivities better than 40  pm/με within the range of 0 to 10  με are achieved. The sensitivity can...

  12. Asymmetric Andreev resonant state with a magnetic exchange field in spin-triplet superconducting monolayer MoS2

    Science.gov (United States)

    Goudarzi, H.; Khezerlou, M.; Ebadzadeh, S. F.

    2018-03-01

    We study the influence of magnetic exchange field (MEF) on the chirality of Andreev resonant state (ARS) appearing at the relating monolayer MoS2 ferromagnet/superconductor interface, in which the induced pairing order parameter is chiral p-wave symmetry. Transmission of low-energy Dirac-like electron (hole) quasiparticles through a ferromagnet/superconductor (F/S) interface is considered based on Dirac-Bogoliubov-de Gennes Hamiltonian and, of course, Andreev reflection process. The magnetic exchange field of a ferromagnetic section on top of ML-MDS may affect the electron (hole) excitations for spin-up and spin-down electrons, differently. We find the chirality symmetry of ARS to be conserved in the absence of MEF, whereas it is broken in the presence of MEF. Tuning the MEF enables one to control either electrical properties (such as band gap, SOC and etc.) or spin-polarized transport. The resulting normal conductance is found to be more sensitive to the magnitude of MEF and doping regime of F region. Unconventional spin-triplet p-wave symmetry features the zero-bias conductance, which strongly depends on p-doping level of F region in the relating NFS junction. A sharp conductance switching in zero is achieved in the absence of SOC.

  13. Very thin spin-coated silver films via transparent silver ink for surface plasmon resonance sensor applications.

    Science.gov (United States)

    Son, Jung-Han; Lee, Dong Hun; Cho, Yong-Jin; Lee, Myung-Hyun

    2012-07-01

    We fabricated very thin silver films with thicknesses of 20 nm, 40 nm, and 60 nm on a prism using a spin coating method for surface plasmon resonance (SPR) image sensor module applications. An aqueous silver ionic complex solution was spin-coated and then thermally cured for 10 minutes at 150 degrees C in an oven. The spin-coated solid silver films possessed silver crystallinity. The prism modules with the 20-nm-, 40-nm- and 60-nm-thick thin silver films were applied to an SPR image sensor system. The coefficients of determination for the 20-nm-, 40-nm- and 60-nm-thick silver films were 0.923, 0.990 and 0.989, respectively when standard ethanol solutions with 0.1% intervals in the range of 20.0% to 20.5% were applied. The correlation is high-performed and the coefficients of determination are as close as 1. The spin coating method of very thin silver films for SPR image sensor modules is expected to be a very cost-effective solution because the films can be formed at a low temperature in a short period of time without requiring a vacuum system.

  14. Spectral and angular characteristics of dielectric resonator metasurface at optical frequencies

    International Nuclear Information System (INIS)

    Zou, Longfang; López-García, Martin; Oulton, Ruth; Klemm, Maciej; Withayachumnankul, Withawat; Fumeaux, Christophe; Shah, Charan M.; Mitchell, Arnan; Bhaskaran, Madhu; Sriram, Sharath

    2014-01-01

    The capability of manipulating light at subwavelength scale has fostered the applications of flat metasurfaces in various fields. Compared to metallic structure, metasurfaces made of high permittivity low-loss dielectric resonators hold the promise of high efficiency by avoiding high conductive losses of metals at optical frequencies. This letter investigates the spectral and angular characteristics of a dielectric resonator metasurface composed of periodic sub-arrays of resonators with a linearly varying phase response. The far-field response of the metasurface can be decomposed into the response of a single grating element (sub-array) and the grating arrangement response. The analysis also reveals that coupling between resonators has a non-negligible impact on the angular response. Over a wide wavelength range, the simulated and measured angular characteristics of the metasurface provide a definite illustration of how different grating diffraction orders can be selectively suppressed or enhanced through antenna sub-array design

  15. Frequency shifts of resonant modes of the Sun due to near-surface convective scattering

    Science.gov (United States)

    Bhattacharya, J.; Hanasoge, S. M.; Antia, H. M.

    Measurements of oscillation frequencies of the Sun and stars can provide important independent constraints on their internal structure and dynamics. Seismic models of these oscillations are used to connect structure and rotation of the star to its resonant frequencies, which are then compared with observations, the goal being that of minimizing the difference between the two. Even in the case of the Sun, for which structure models are highly tuned, observed frequencies show systematic deviations from modeled frequencies, a phenomenon referred to as the ``surface term.'' The dominant source of this systematic effect is thought to be vigorous near-surface convection, which is not well accounted for in both stellar modeling and mode-oscillation physics. Here we bring to bear the method of homogenization, applicable in the asymptotic limit of large wavelengths (in comparison to the correlation scale of convection), to characterize the effect of small-scale surface convection on resonant-mode frequencies in the Sun. We show that the full oscillation equations, in the presence of temporally stationary 3D flows, can be reduced to an effective ``quiet-Sun'' wave equation with altered sound speed, Brünt-Väisäla frequency, and Lamb frequency. We derive the modified equation and relations for the appropriate averaging of 3D flows and thermal quantities to obtain the properties of this effective medium. Using flows obtained from 3D numerical simulations of near-surface convection, we quantify their effect on solar oscillation frequencies and find that they are shifted systematically and substantially. We argue therefore that consistent interpretations of resonant frequencies must include modifications to the wave equation that effectively capture the impact of vigorous hydrodynamic convection.

  16. FREQUENCY SHIFTS OF RESONANT MODES OF THE SUN DUE TO NEAR-SURFACE CONVECTIVE SCATTERING

    International Nuclear Information System (INIS)

    Bhattacharya, J.; Hanasoge, S.; Antia, H. M.

    2015-01-01

    Measurements of oscillation frequencies of the Sun and stars can provide important independent constraints on their internal structure and dynamics. Seismic models of these oscillations are used to connect structure and rotation of the star to its resonant frequencies, which are then compared with observations, the goal being that of minimizing the difference between the two. Even in the case of the Sun, for which structure models are highly tuned, observed frequencies show systematic deviations from modeled frequencies, a phenomenon referred to as the “surface term.” The dominant source of this systematic effect is thought to be vigorous near-surface convection, which is not well accounted for in both stellar modeling and mode-oscillation physics. Here we bring to bear the method of homogenization, applicable in the asymptotic limit of large wavelengths (in comparison to the correlation scale of convection), to characterize the effect of small-scale surface convection on resonant-mode frequencies in the Sun. We show that the full oscillation equations, in the presence of temporally stationary three-dimensional (3D) flows, can be reduced to an effective “quiet-Sun” wave equation with altered sound speed, Brünt–Väisäla frequency, and Lamb frequency. We derive the modified equation and relations for the appropriate averaging of 3D flows and thermal quantities to obtain the properties of this effective medium. Using flows obtained from 3D numerical simulations of near-surface convection, we quantify their effect on solar oscillation frequencies and find that they are shifted systematically and substantially. We argue therefore that consistent interpretations of resonant frequencies must include modifications to the wave equation that effectively capture the impact of vigorous hydrodynamic convection

  17. Electron spin resonance analysis of magnetic structures in La2/3Ca1/3MnO3

    International Nuclear Information System (INIS)

    Ding Tao; Zheng Weitao; Zang Jianfeng; Tian Hongwei; Zheng Bing; Wang Xin; Yu Shansheng; Wang Yuming

    2005-01-01

    Measurements of electron spin resonance (ESR) of La 2/3 Ca 1/3 MnO 3 (LCMO) in the ferromagnetic and paramagnetic phases were carried out. Phase transition and temperature dependence of the peak-to-peak ESR linewidth were determined. The transition temperature between ferromagnetic and paramagnetic phases was observed at 265 K. A prominent increase of the peak-to-peak linewidth with decreasing temperature below T c was observed. Using the dynamic scale theory and block spin transformation in critical phenomenon, the quantitative calculation of peak-to-peak linewidth at near T c was made, which was in good agreement with the experimental data. It was believed that the long interactions between the ferromagnetic microregions for LCMO played a key role in determining the ESR linewidth

  18. Studi Spektroskopi Electron Spin Resonance (Esr Lapisan Tipis Amorf Silikon Karbon (A-Sic:H Hasil Deposisi Metode Dc Sputtering

    Directory of Open Access Journals (Sweden)

    Rosari Saleh

    2002-04-01

    Full Text Available The dangling bond defect density in sputtered amorphous silicon carbon alloys have been studied by electron spin resonance (ESR. The results show that the spin density decreased slightly with increasing methane fl ow rate (CH4. The infl uence of carbon and hydrogen incorporation on g-value revealed that for CH4 fl ow rate up to 8 sccm, the ESR signal is dominated by defects characteristic of a-Si:H fi lms and for CH4 fl ow rate higher than 8 sccm the g-value decreased towards those usually found in a-C:H fi lms. Infrared (IR results suggest that as CH4 fl ow rate increases more carbon and hydrogen is incorporated into the fi lms to form Si-H, Si-C and C-H bonds. A direct relation between the IR results and the defect density and g-value is observed.

  19. Electronic spin resonance quantitative analysis of Mn(II) complexes anti oxidative activity using phosphate or organic buffer

    Energy Technology Data Exchange (ETDEWEB)

    Souchard, J.P.; Massol, M.; Nepveu, F. [Toulouse-3 Univ., 31 (France)

    1996-01-01

    Superoxide anion is implicated in the pathogenesis of several human diseases including ischaemia, atherosclerosis and inflammation when molecular or enzymatic antioxidant systems cannot regulate its formation. In order to investigate superoxide dismutase (SOD) mimics, a method using Electron Spin Resonance (ESR) has been developed to quantify anti-oxidative activities of Mn(II) compounds. The acetaldehyde / xanthine oxidase system produced superoxide anion and the 5,5-dimethyl-I-pyroline-N-oxide (DMPO) was used as spin trap. The complexing properties of the usual phosphate buffer towards Mn{sup 2+} being not negligible comparatively to those of the studied ligands, activities of free ligands and Mn(II) complexes have been compared according to the buffer, phosphate or organic. (Authors). 7 refs., 1 tab., 2 figs.,.

  20. Role of high-spin hyperon resonances in the reaction of $\\gamma p \\to K^+ K^+ \\Xi^-$

    Energy Technology Data Exchange (ETDEWEB)

    J. Ka Shing Man, Yongseok Oh, K. Nakayama

    2011-05-01

    The recent data taken by the CLAS Collaboration at the Thomas Jefferson National Accelerator Facility for the reaction of $\\gamma p \\to K^+ K^+ \\Xi^-$ are reanalyzed within a relativistic meson-exchange model of hadronic interactions. The present model is an extension of the one developed in an earlier work by Nakayama, Oh, and Haberzettl [Phys. Rev. C 74, 035205 (2006)]. In particular, the role of the spin-5/2 and -7/2 hyperon resonances, which were not included in the previous model, is investigated in the present study. It is shown that the contribution of the $\\Sigma(2030)$ hyperon having spin-7/2 and positive parity has a key role to bring the model predictions into a fair agreement with the measured data for the $K^+\\Xi^-$ invariant mass distribution.

  1. Spin-transfer measurements of the π rvec d→ rvec pp reaction at energies spanning the Δ resonance

    International Nuclear Information System (INIS)

    Feltham, A.; Jones, G.; Olszewski, R.; Pavan, M.; Sevior, M.; Trelle, R.P.; Weber, P.; Lolos, G.J.; Mathie, E.L.; Papandreou, Z.; Rui, R.; Gill, D.; Healey, D.; Ottewell, D.; Sheffer, G.; Smith, G.R.; Sossi, V.; Wait, G.; Walden, P.

    1997-01-01

    The first spin-transfer experiment performed for the π rvec d→ rvec pp reaction is described. Three spin-transfer parameters for this π-absorption process were determined, K LS a , K SS a , and K NN a , which correspond to the π-production parameters, K SL p , K SS p , and K NN p , of the time-reversed rvec pp→ rvec dπ process. Each observable was measured at a single angle for a number of energies spanning the Δ resonance of this system. The results are compared with the predictions of published partial wave amplitude fits which are primarily based on existing data for the time-reversed pp→dπ reaction, and also with the predictions of two current theories. The failure of these theories to describe the fundamental features of the data clearly demonstrates the need for further theoretical work in this area. copyright 1997 The American Physical Society

  2. Micropillar Resonators for Optomechanics in the Extremely High 19-95-GHz Frequency Range

    Science.gov (United States)

    Anguiano, S.; Bruchhausen, A. E.; Jusserand, B.; Favero, I.; Lamberti, F. R.; Lanco, L.; Sagnes, I.; Lemaître, A.; Lanzillotti-Kimura, N. D.; Senellart, P.; Fainstein, A.

    2017-06-01

    Strong confinement, in all dimensions, and high mechanical frequencies are highly desirable for quantum optomechanical applications. We show that GaAs/AlAs micropillar cavities fully confine not only photons but also extremely high frequency (19-95 GHz) acoustic phonons. A strong increase of the optomechanical coupling upon reducing the pillar size is observed, together with record room-temperature Q -frequency products of 1 014. These mechanical resonators can integrate quantum emitters or polariton condensates, opening exciting perspectives at the interface with nonlinear and quantum optics.

  3. Direct Observation of the Quantum Phase Transition of SrCu2(BO3)2 by High-Pressure and Terahertz Electron Spin Resonance

    Science.gov (United States)

    Sakurai, Takahiro; Hirao, Yuki; Hijii, Keigo; Okubo, Susumu; Ohta, Hitoshi; Uwatoko, Yoshiya; Kudo, Kazutaka; Koike, Yoji

    2018-03-01

    High-pressure and high-field electron spin resonance (ESR) measurements have been performed on a single crystal of the orthogonal-dimer spin system SrCu2(BO3)2. With frequencies below 1 THz, ESR signals associated with transitions from the singlet ground state to the one-triplet excited states and the two-triplet bound state were observed at pressures up to 2.1 GPa. We obtained directly the pressure dependence of the gap energies, finding a clear first-order phase transition at Pc = 1.85 ± 0.05 GPa. By comparing this pressure dependence with the calculated excitation energies obtained from an exact diagonalization, we determined the precise pressure dependence for inter- (J') and intra-dimer (J) exchange interactions considering the Dzyaloshinski-Moriya interaction. Thus this system undergoes a first-order quantum phase transition from the dimer singlet phase to a plaquette singlet phase above the ratio (J'/J)c = 0.660 ± 0.003.

  4. Exploiting NiTi shape memory alloy films in design of tunable high frequency microcantilever resonators

    Science.gov (United States)

    Stachiv, I.; Sittner, P.; Olejnicek, J.; Landa, M.; Heller, L.

    2017-11-01

    Shape memory alloy (SMA) films are very attractive materials for microactuators because of their high energy density. However, all currently developed SMA actuators utilize martensitic transformation activated by periodically generated heating and cooling; therefore, they have a slow actuation speed, just a few Hz, which restricts their use in most of the nanotechnology applications such as high frequency microcantilever based physical and chemical sensors, atomic force microscopes, or RF filters. Here, we design tunable high frequency SMA microcantilevers for nanotechnology applications. They consist of a phase transforming NiTi SMA film sputtered on the common elastic substrate material; in our case, it is a single-crystal silicon. The reversible tuning of microcantilever resonant frequencies is then realized by intentionally changing the Young's modulus and the interlayer stress of the NiTi film by temperature, while the elastic substrate guarantees the high frequency actuation (up to hundreds of kHz) of the microcantilever. The experimental results qualitatively agree with predictions obtained from the dedicated model based on the continuum mechanics theory and a phase characteristic of NiTi. The present design of SMA microcantilevers expands the capability of current micro-/nanomechanical resonators by enabling tunability of several consecutive resonant frequencies.

  5. Stark-state resonances induced by low-frequency elliptically polarized fields

    Science.gov (United States)

    Richards, D.

    1997-09-01

    We analyse the effect of a low-frequency elliptically polarized electric field on an excited hydrogen atom using classical dynamics. It is shown that at particular frequencies the ionization probability is a non-monotonic function of the field strength and that at these frequencies the classical ionization probabilities agree well with those of experiment. We show that this unusual behaviour is produced by resonance between Stark states and the driving field near the circularly polarized limit. By averaging over the fast motion, to produce a mean-motion approximation, we show how the resonance affects the motion and that the effect is different according to whether the electron is initially rotating in the same or in the opposite direction to the field.

  6. Estimation of body resonances from a time-frequency analysis of violin vibrato

    Science.gov (United States)

    Mellody, Maureen; Wakefield, Gregory H.

    1999-11-01

    We present a signal-based technique for evaluating a pole-zero representation of the resonant response of a violin instrument. This technique combines time-frequency signal analysis with system identification techniques to determine the pole-zero function that would account for amplitude modulation observed on the partials of violin notes performed with vibrato. Violin vibrato signals are analyzed with the modal distribution to obtain values of instantaneous amplitude and frequency for each partial. From these, input and output functions are synthesized and used to estimate the violin body's impulse response using an infinite impulse response (IIR) system identification procedure. In each case, the input and output functions share the same instantaneous frequency of the measured partial. However, the rapid amplitude variations are present only on the output function. We report on the location and spacing of these estimated resonances and discuss their relationship to those obtained from theoretical predictions and other measurement procedures.

  7. Characterization of the sp sup 2 bonds network in a-C:H layers with nuclear magnetic resonance, electron energy loss spectroscopy and electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Kleber, R.; Jung, K.; Ehrhardt, H. (Fachbereich Physik, Univ. Kaiserslautern (Germany)); Muehling, I.; Breuer, K. (Technische Univ. Chemnitz, Sektion Physik/Elektronische Bauelemente (Germany)); Metz, H.; Engelke, F. (Karl-Marx-Univ., Sektion Physik, Leipzig (Germany))

    1991-12-01

    a-C:H layers prepared at different ion energies have been investigated by several methods including {sup 13}C nuclear magnetic resonance (NMR), electron energy loss spectroscopy (EELS) and electron spin resonance (ESR). The sp{sup 2} fraction of the samples rose from 27% to about 60 at.% with increasing ion energies from 30 eV to 170 eV. In the EELS spectra of these layers the intensity of the {pi}{yields}{pi}{sup *} transition between 4 and 7 eV showed no significant variation. But a shift of the peak is observed from 7 eV to lower energy losses with increasing ion energies indicating an enhanced formation of larger sp{sup 2} cluster sizes. This shift is accompanied by a broadening of the energy loss peak, suggesting a broadening of the cluster size distribution. The ESR spectra showed an increase of the spin density by more than one order of magnitude with increasing ion energies. Simultaneously the linewidth of the ESR signal gets narrower. This can also be interpreted as an increasing cluster size from single benzene rings to three and four fused six-fold rings. Hence, the EELS and ESR spectra lead to the same conclusions with respect to the microstructure of the a-C:H network. (orig.).

  8. The analysis of demodulation characteristic on the resonant optical gyro using frequency modulation technique

    Science.gov (United States)

    Ning, Liang; Guo, Lijun; Fang, Gang; Liu, Cihang

    2015-03-01

    The resonator optic gyro (ROG), which utilizes a resonance frequency change due to the Sagnac effect, is a promising candidate for the next generation inertial rotation sensor. In this paper, we first analyzed the signal detection theory and made the demodulation curve modeling. Second, the ROG demodulation test system is set up using the laser frequency modulation spectroscopy technique. The resonance curve of the resonator is detected by the photodiode (PD) and then demodulated by the LIA. By testing at λ=1550nm, and the free spectral range (FSR), the full width at half maximum (FWHM), the depth and the finesse of resonance are 2191.41MHz, 65.55MHz, 0.9 and 33.43 respectively. Calculated from the demodulation signal, the dynamic range of the gyro is from +2.04×103rad/s to -2.04×103rad/s. The slope K1 of the linear part in the demodulation signal is estimated to be 0.8×10-7V/Hz. A basic agreement between experimental results and theoretical calculated values was achieved.

  9. Cross polarization, magic-angle spinning /sup 13/C nuclear magnetic resonance spectroscopy of soil humic fractions

    Energy Technology Data Exchange (ETDEWEB)

    Saiz-Jimenez, C.; Hawkins, B.L.; Maciel, G.E.

    1986-01-01

    Cross polarization, magic-angle spinning /sup 13/C nuclear magnetic resonance spectroscopy was used to characterize humic fractions isolated from different soils. The humic acid fractions are more aromatic than the humin fractions, probably due to the higher polysaccharide content of humins. However, fulvic acid fractions are more aromatic than the corresponding humic acid and humin fractions. These results can be interpreted in terms of the isolation procedure, because the high affinity of Polyclar AT for phenols results in higher aromaticities as compared with other isolation methods (e.g. charcoal).

  10. Electron spin resonance of thin films of organic light-emitting material tris(8-hydroxyquinoline) aluminum doped by magnesium

    OpenAIRE

    Son, Donghyun; Marumoto, Kazuhiro; Kizuka, Tokushi; Shimoi, Yukihiro

    2012-01-01

    We have successfully observed electron spin resonance (ESR) signals of radical anions in thin films of tris(8-hydroxyquinoline) aluminum (Alq3), a compound widely used as electron transporting and luminescent layers in organic light-emitting diodes. To obtain definitely defined radical-anion states in Alq3, we doped Alq3 with Mg by co-evaporating these materials. The obtained g value and peak-to-peak ESR linewidth ΔHpp of Alq3 radical anions are 2.0030 and 2.19 mT, respectively. Theoretical g...

  11. Repetition rate multiplication of frequency comb using all-pass fiber resonator

    International Nuclear Information System (INIS)

    Yang, Lijun; Yang, Honglei; Zhang, Hongyuan; Wei, Haoyun; Li, Yan

    2016-01-01

    We propose a stable method for repetition rate multiplication of a 250-MHz Er-fiber frequency comb by a phase-locked all-pass fiber ring resonator, whose phase-locking configuration is simple. The optical path length of the fiber ring resonator is automatically controlled to be accurately an odd multiple of half of the original cavity length using an electronical phase-locking unit with an optical delay line. As for shorter cavity length of the comb, high-order odd multiple is preferable. Because the power loss depends only on the net-attenuation of the fiber ring resonator, the energetic efficiency of the proposed method is high. The input and output optical spectrums show that the spectral width of the frequency comb is clearly preserved. Besides, experimental results show less pulse intensity fluctuation and 35 dB suppression ratio of side-modes while providing a good long-term and short-term frequency stability. Higher-order repetition rate multiplication to several GHz can be obtained by using several fiber ring resonators in cascade configuration.

  12. Frequency-comb formation in doubly resonant second-harmonic generation

    Science.gov (United States)

    Leo, F.; Hansson, T.; Ricciardi, I.; De Rosa, M.; Coen, S.; Wabnitz, S.; Erkintalo, M.

    2016-04-01

    We theoretically study the generation of optical frequency combs and corresponding pulse trains in doubly resonant intracavity second-harmonic generation (SHG). We find that, despite the large temporal walk-off characteristic of realistic cavity systems, the nonlinear dynamics can be accurately and efficiently modeled using a pair of coupled mean-field equations. Through rigorous stability analysis of the system's steady-state continuous-wave solutions, we demonstrate that walk-off can give rise to an unexplored regime of temporal modulation instability. Numerical simulations performed in this regime reveal rich dynamical behaviors, including the emergence of temporal patterns that correspond to coherent optical frequency combs. We also demonstrate that the two coupled equations that govern the doubly resonant cavity behavior can, under typical conditions, be reduced to a single mean-field equation akin to that describing the dynamics of singly-resonant-cavity SHG [F. Leo et al., Phys. Rev. Lett. 116, 033901 (2016), 10.1103/PhysRevLett.116.033901]. This reduced approach allows us to derive a simple expression for the modulation instability gain, thus permitting us to acquire significant insight into the underlying physics. We anticipate that our work will have a wide impact on the study of frequency combs in emerging doubly resonant cavity SHG platforms, including quadratically nonlinear microresonators.

  13. Particle acceleration through the resonance of high magnetic field and high frequency electromagnetic wave

    International Nuclear Information System (INIS)

    Hong, Liu; He, X.T.; Chen, S.G.; Zhang, W.Y.; He, X.T.; Hong, Liu

    2004-01-01

    We propose a new particle acceleration mechanism. Electrons can be accelerated to relativistic energy within a few electromagnetic wave cycles through the mechanism which is named electromagnetic and magnetic field resonance acceleration (EMRA). We find that the electron acceleration depends not only on the electromagnetic wave intensity, but also on the ratio between electron Larmor frequency and electromagnetic wave frequency. As the ratio approaches to unity, a clear resonance peak is observed, corresponding to the EMRA. Near the resonance regime, the strong magnetic fields still affect the electron acceleration dramatically. We derive an approximate analytical solution of the relativistic electron energy in adiabatic limit, which provides a full understanding of this phenomenon. In typical parameters of pulsar magnetospheres, the mechanism allows particles to increase their energies through the resonance of high magnetic field and high frequency electromagnetic wave in each electromagnetic wave period. The energy spectra of the accelerated particles exhibit the synchrotron radiation behavior. These can help to understand the remaining emission of high energy electron from radio pulsar within supernova remnant. The other potential application of our theory in fast ignition scheme of inertial confinement fusion is also discussed. (authors)

  14. Repetition rate multiplication of frequency comb using all-pass fiber resonator.

    Science.gov (United States)

    Yang, Lijun; Yang, Honglei; Zhang, Hongyuan; Wei, Haoyun; Li, Yan

    2016-09-01

    We propose a stable method for repetition rate multiplication of a 250-MHz Er-fiber frequency comb by a phase-locked all-pass fiber ring resonator, whose phase-locking configuration is simple. The optical path length of the fiber ring resonator is automatically controlled to be accurately an odd multiple of half of the original cavity length using an electronical phase-locking unit with an optical delay line. As for shorter cavity length of the comb, high-order odd multiple is preferable. Because the power loss depends only on the net-attenuation of the fiber ring resonator, the energetic efficiency of the proposed method is high. The input and output optical spectrums show that the spectral width of the frequency comb is clearly preserved. Besides, experimental results show less pulse intensity fluctuation and 35 dB suppression ratio of side-modes while providing a good long-term and short-term frequency stability. Higher-order repetition rate multiplication to several GHz can be obtained by using several fiber ring resonators in cascade configuration.

  15. Resonance Frequency and Bandwidth of the Negative/Positive n Mode of a Composite Right-/Left-Handed Transmission Line

    Directory of Open Access Journals (Sweden)

    Seong-Jung Kim

    2018-01-01

    Full Text Available In this study, the analytic expression for the positive/negative nth-mode resonance frequency of an N unit cell composite right-/left-handed (CRLH transmission line is derived. To explain the resonance mechanism of the nth mode, especially for the negative mode, the current distribution of the N unit cell CRLH transmission line is investigated with a circuit simulation. Results show that both positive and negative nth resonance modes have n times current variations, but their phase difference is 180° as expected. Moreover, the positive nth resonance occurs at a high frequency, whereas the negative nth resonance transpires at a low frequency, thus indicating that the negative resonance mode can be utilized for a small resonator. The correlation between the slope of the dispersion curve and the bandwidth is also observed. In sum, the balanced condition of the CRLH transmission line provides a broader bandwidth than the unbalanced condition.

  16. Decoherence dynamics of a single spin versus spin ensemble

    NARCIS (Netherlands)

    Dobrovitski, V.V.; Feiguin, A.E.; Awschalom, D.D.; Hanson, R.

    2008-01-01

    We study decoherence of central spins by a spin bath, focusing on the difference between measurement of a single central spin and measurement of a large number of central spins (as found in typical spin-resonance experiments). For a dilute spin bath, the single spin demonstrates Gaussian

  17. The internal dynamics of mini c TAR DNA probed by electron paramagnetic resonance of nitroxide spin-labels at the lower stem, the loop, and the bulge.

    Science.gov (United States)

    Sun, Yan; Zhang, Ziwei; Grigoryants, Vladimir M; Myers, William K; Liu, Fei; Earle, Keith A; Freed, Jack H; Scholes, Charles P

    2012-10-30

    Electron paramagnetic resonance (EPR) at 236.6 and 9.5 GHz probed the tumbling of nitroxide spin probes in the lower stem, in the upper loop, and near the bulge of mini c TAR DNA. High-frequency 236.6 GHz EPR, not previously applied to spin-labeled oligonucleotides, was notably sensitive to fast, anisotropic, hindered local rotational motion of the spin probe, occurring approximately about the NO nitroxide axis. Labels attached to the 2'-aminocytidine sugar in the mini c TAR DNA showed such anisotropic motion, which was faster in the lower stem, a region previously thought to be partially melted. More flexible labels attached to phosphorothioates at the end of the lower stem tumbled isotropically in mini c TAR DNA, mini TAR RNA, and ψ(3) RNA, but at 5 °C, the motion became more anisotropic for the labeled RNAs, implying more order within the RNA lower stems. As observed by 9.5 GHz EPR, the slowing of nanosecond motions of large segments of the oligonucleotide was enhanced by increasing the ratio of the nucleocapsid protein NCp7 to mini c TAR DNA from 0 to 2. The slowing was most significant at labels in the loop and near the bulge. At a 4:1 ratio of NCp7 to mini c TAR DNA, all labels reported tumbling times of >5 ns, indicating a condensation of NCp7 and TAR DNA. At the 4:1 ratio, pulse dipolar EPR spectroscopy of bilabels attached near the 3' and 5' termini showed evidence of an NCp7-induced increase in the 3'-5' end-to-end distance distribution and a partially melted stem.

  18. Quantum measurements between a single spin and a torsional nanomechanical resonator

    Science.gov (United States)

    D'Urso, B.; Gurudev Dutt, M. V.; Dhingra, S.; Nusran, N. M.

    2011-04-01

    While the motions of macroscopic objects must ultimately be governed by quantum mechanics, the distinctive features of quantum mechanics can be hidden or washed out by thermal excitations and coupling to the environment. We propose a system consisting of a graphene nanomechanical oscillator (NMO) coupled with a single spin through a uniform external magnetic field, which could become the building block for a wide range of quantum nanomechanical devices. The choice of graphene as the NMO material is critical for minimizing the moment of inertia of the oscillator. The spin originates from a nitrogen-vacancy (NV) center in a diamond nanocrystal that is positioned on the NMO. This coupling results in quantum non-demolition (QND) measurements of the oscillator and spin states, enabling a bridge between the quantum and classical worlds for a simple readout of the NV center spin and observation of the discrete states of the NMO.

  19. Finite size effect on spread of resonance frequencies in arrays of coupled vortices

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, Andreas; Drews, André; Im, Mi-Young; Fischer, Peter; Meier, Guido

    2011-01-25

    Dynamical properties of magnetic vortices in arrays of magnetostatically coupled ferromagnetic disks are studied by means of a broadband ferromagnetic-resonance (FMR) setup. Magnetic force microscopy and magnetic transmission soft X-ray microscopy are used to image the core polarizations and the chiralities which are both found to be randomly distributed. The resonance frequency of vortex-core motion strongly depends on the magnetostatic coupling between the disks. The parameter describing the relative broadening of the absorption peak observed in the FMR transmission spectra for a given normalized center-to-center distance between the elements is shown to depend on the size of the array.

  20. Topology optimization of multi-track ring resonators and 2D microcavities for nonlinear frequency conversion.

    Science.gov (United States)

    Lin, Zin; Lončar, Marko; Rodriguez, Alejandro W

    2017-07-15

    We exploit recently developed topology-optimization techniques to design complex, wavelength-scale resonators for enhancing various nonlinear χ(2) and χ(3) frequency conversion processes. In particular, we demonstrate aperiodic, multi-track ring resonators and two-dimensional slab microcavities exhibiting long lifetimes Q≳104, small modal volumes V≳(λ/2n)3, and among the largest nonlinear overlaps (a generalization of phase matching in large-etalon waveguides) possible, paving the way for efficient, compact, and wide-bandwdith integrated nonlinear devices.

  1. Frequency, amplitude, and phase measurements in contact resonance atomic force microscopies

    Directory of Open Access Journals (Sweden)

    Gheorghe Stan

    2014-03-01

    Full Text Available The resonance frequency, amplitude, and phase response of the first two eigenmodes of two contact-resonance atomic force microscopy (CR-AFM configurations, which differ in the method used to excite the system (cantilever base vs sample excitation, are analyzed in this work. Similarities and differences in the observables of the cantilever dynamics, as well as the different effect of the tip–sample contact properties on those observables in each configuration are discussed. Finally, the expected accuracy of CR-AFM using phase-locked loop detection is investigated and quantification of the typical errors incurred during measurements is provided.

  2. Applications of pulsed nuclear magnetic resonance to chemistry: multiple-pulse NMR, cross polarization, magic-angle spinning annd instrumental design

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, P.D.

    1979-07-01

    Pulsed Nuclear Magnetic Resonance (NMR) has been applied to: (1) Measurements of the prinicpal components of the proton shielding tensors of the hydrides of zirconium chloride and zirconium bromide. Multiple-Pulse techniques have been used to remove static homonuclear dipolar coupling. The anisotropies and isotropic shifts of these tensors have been used to infer the possible locations of the hydrogen within the sandwich-like layers of these unusual compounds. (2) Studies of the oscillatory transfer of magnetic polarization between /sup 1/H and /sup 29/Si in substituted silanes. The technique of J Cross Polarization has been used to enhance sensitivity. The /sup 29/Si NMR shifts of -Si-O- model compounds have been investigated as a possible probe for future studies of the environment of bound oxygen in coal-derived liquids. (3) Measurements of the aromatic fraction of /sup 13/C in whole coals. The techniques of /sup 1/H-/sup 13/C Cross Polarization and Magic-Angle Spinning have been used to enhance sensitivity and remove shift anisotropy. Additional topics described are: (4) Calculation and properties of the broadened lineshape of the shileding Powder Pattern. (5) Calculation of the oscillatory transfer of magnetic polarization for an I-S system. (6) Numerical convolution and its uses. (7) The technique of digital filtering applied in the frequency domain. (8) The designs and properties of four NMR probe-circuits. (9) The design of a single-coil double-resonance probe for combined Magic-Angle Spinning and Cross Polarization. (10) The designs of low Q and high Q rf power amplifiers with emphasis on the rf matching circuitry.

  3. Partitioning of small amphiphiles at surfactant bilayer/water interfaces: an avoided level crossing muon spin resonance study.

    Science.gov (United States)

    Scheuermann, Robert; Tucker, Ian M; Dilger, Herbert; Staples, Ed J; Ford, Gary; Fraser, Stuart B; Beck, Bettina; Roduner, Emil

    2004-03-30

    The temperature-dependent variation of local environment and reorientation dynamics of the small amphiphile 2-phenylethanol in lamellar phase dispersions of the dichain cationic surfactants, 2,3-diheptadecyl ester ethoxypropyl-1,1,1-trimethylammonium chloride (DHTAC) and dioctadecyldimethylammonium chloride (DODMAC), and the nonionic surfactant, tetra(ethylene glycol) n-dodecyl ether (C12E4), have been determined using avoided level crossing muon spin resonance spectroscopy (ALC-muSR). For cosurfactant radicals the hydrophobic or hydrophilic character of the surrounding media can be determined from their magnetic resonance signatures. Comparison of the three different bilayer-forming surfactant systems shows that the ALC-muSR technique is able to distinguish both major and subtle differences in the partitioning of the cosurfactant radicals between the different systems.

  4. Fabrication and characterization of non-resonant magneto-mechanical low-frequency vibration energy harvester

    Science.gov (United States)

    Nammari, Abdullah; Caskey, Logan; Negrete, Johnny; Bardaweel, Hamzeh

    2018-03-01

    This article presents a non-resonant magneto-mechanical vibration energy harvester. When externally excited, the energy harvester converts vibrations into electric charge using a guided levitated magnet oscillating inside a multi-turn coil that is fixed around the exterior of the energy harvester. The levitated magnet is guided using four oblique mechanical springs. A prototype of the energy harvester is fabricated using additive manufacturing. Both experiment and model are used to characterize the static and dynamic behavior of the energy harvester. Measured restoring forces show that the fabricated energy harvester retains a mono-stable potential energy well with desired stiffness nonlinearities. Results show that magnetic spring results in hardening effect which increases the resonant frequency of the energy harvester. Additionally, oblique mechanical springs introduce geometric, negative, nonlinear stiffness which improves the harvester's response towards lower frequency spectrum. The unique design can produce a tunable energy harvester with multi-well potential energy characteristics. A finite element model is developed to estimate the average radial flux density experienced by the multi-turn coil. Also, a lumped parameter model of the energy harvester is developed and validated against measured data. Both upward and downward frequency sweeps are performed to determine the frequency response of the harvester. Results show that at higher excitation levels hardening effects become more apparent, and the system dynamic response turns into non-resonant. Frequency response curves exhibit frequency jump phenomena as a result of coexistence of multiple energy states at the frequency branch. The fabricated energy harvester is hand-held and measures approximately 100.5 [cm3] total volume. For a base excitation of 1.0 g [m/s2], the prototype generates a peak voltage and normalized power density of approximately 3.5 [V] and 0.133 [mW/cm3 g2], respectively, at 15.5 [Hz].

  5. HIGHER MODE FREQUENCY EFFECTS ON RESONANCE IN MACHINERY, STRUCTURES, AND PIPE SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Leishear, R.

    2010-05-02

    The complexities of resonance in multi-degree of freedom systems (multi-DOF) may be clarified using graphic presentations. Multi-DOF systems represent actual systems, such as beams or springs, where multiple, higher order, natural frequencies occur. Resonance occurs when a cyclic load is applied to a structure, and the frequency of the applied load equals one of the natural frequencies. Both equations and graphic presentations are available in the literature for single degree of freedom (SDOF) systems, which describe the response of spring-mass-damper systems to harmonically applied, or cyclic, loads. Loads may be forces, moments, or forced displacements applied to one end of a structure. Multi-DOF systems are typically described only by equations in the literature, and while equations certainly permit a case by case analysis for specific conditions, graphs provide an overall comprehension not gleaned from single equations. In fact, this collection of graphed equations provides novel results, which describe the interactions between multiple natural frequencies, as well as a comprehensive description of increased vibrations near resonance.

  6. Two Novel Measurements for the Drive-Mode Resonant Frequency of a Micromachined Vibratory Gyroscope

    Directory of Open Access Journals (Sweden)

    Ancheng Wang

    2013-11-01

    Full Text Available To investigate the drive-mode resonance frequency of a micromachined vibratory gyroscope (MVG, one needs to measure it accurately and efficiently. The conventional approach to measure the resonant frequency is by performing a sweep frequency test and spectrum analysis. The method is time-consuming and inconvenient because of the requirements of many test points, a lot of data storage and off-line analyses. In this paper, we propose two novel measurement methods, the search method and track method, respectively. The former is based on the magnitude-frequency characteristics of the drive mode, utilizing a one-dimensional search technique. The latter is based on the phase-frequency characteristics, applying a feedback control loop. Their performances in precision, noise resistivity and efficiency are analyzed through detailed simulations. A test system is implemented based on a field programmable gate array (FPGA and experiments are carried out. By comparing with the common approach, feasibility and superiorities of the proposed methods are validated. In particular, significant efficiency improvements are achieved whereby the conventional frequency method consumes nearly 5,000 s to finish a measurement, while only 5 s is needed for the track method and 1 s for the search method.

  7. Multi frequency excited MEMS cantilever beam resonator for Mixer-Filter applications

    KAUST Repository

    Chandran, Akhil A.

    2016-09-15

    Wireless communication uses Radio Frequency waves to transfer information from one point to another. The modern RF front end devices are implementing MEMS in their designs so as to exploit the inherent properties of MEMS devices, such as its low mass, low power consumption, and small size. Among the components in the RF transceivers, band pass filters and mixers play a vital role in achieving the optimum RF performance. And this paper aims at utilizing an electrostatically actuated micro cantilever beam resonator\\'s nonlinear frequency mixing property to realize a Mixer-Filter configuration through multi-frequency excitation. The paper studies about the statics and dynamics of the device. Simulations are carried out to study the added benefits of multi frequency excitation. The modelling of the cantilever beam has been done using a Reduced Order Model of the Euler-Bernoulli\\'s beam equation by implementing the Galerkin discretization. The device is shown to be able to down-convert signals from 960 MHz of frequency to an intermediate frequency around 50 MHz and 70 MHz in Phase 1 and 2, respectively. The simulation showed promising results to take the project to the next level. © 2016 IEEE.

  8. Optical-optical double resonance, laser induced fluorescence, and revision of the signs of the spin-spin constants of the boron carbide (BC) free radical.

    Science.gov (United States)

    Sunahori, Fumie X; Nagarajan, Ramya; Clouthier, Dennis J

    2015-12-14

    The cold boron carbide free radical (BC X (4)Σ(-)) has been produced in a pulsed discharge free jet expansion using a precursor mixture of trimethylborane in high pressure argon. High resolution laser induced fluorescence spectra have been obtained for the B (4)Σ(-)-X (4)Σ(-) and E (4)Π-X (4)Σ(-) band systems of both (11)BC and (10)BC. An optical-optical double resonance (OODR) scheme was implemented to study the finer details of both band systems. This involved pumping a single rotational level of the B state with one laser and then recording the various allowed transitions from the intermediate B state to the final E state with a second laser by monitoring the subsequent E-X ultraviolet fluorescence. In this fashion, we were able to prove unambiguously that, contrary to previous studies, the spin-spin constant λ is negative in the ground state and positive in the B (4)Σ(-) excited state. It has been shown that λ″ < 0 is in fact expected based on a semiempirical second order perturbation theory calculation of the magnitude of the spin-spin constant. The OODR spectra have also been used to validate our assignments of the complex and badly overlapped E (4)Π-X (4)Σ(-) 0-0 and 1-0 bands of (11)BC. The E-X 0-0 band of (10)BC was found to be severely perturbed. The ground state main electron configuration is …3σ(2)4σ(2)5σ(1)1π(2)2π(0) and the derived bond lengths show that there is a 0.03 Å contraction in the B state, due to the promotion of an electron from the 4σ antibonding orbital to the 5σ bonding orbital. In contrast, the bond length elongates by 0.15 Å in the E state, a result of promoting an electron from the 5σ bonding orbital to the 2π antibonding orbitals.

  9. Electron spin resonance insight into broadband absorption of the Cu{sub 3}Bi(SeO{sub 3}){sub 2}O{sub 2}Br metamagnet

    Energy Technology Data Exchange (ETDEWEB)

    Zorko, A., E-mail: andrej.zorko@ijs.si; Gomilšek, M.; Pregelj, M. [Jožef Stefan Institute, Jamova c. 39, SI-1000 Ljubljana (Slovenia); Ozerov, M.; Zvyagin, S. A. [Dresden High Magnetic Field Laboratory, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden (Germany); Ozarowski, A. [National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310 (United States); Tsurkan, V. [Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg (Germany); Institute of Applied Physics, Academy of Science of Moldova, MD-2028 Chisinau, Republic of Moldova (Moldova, Republic of); Loidl, A. [Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg (Germany); Zaharko, O. [Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)

    2016-05-15

    Metamagnets, which exhibit a transition from a low-magnetization to a high-magnetization state induced by the applied magnetic field, have recently been highlighted as promising materials for controllable broadband absorption. Here we show results of a multifrequency electron spin resonance (ESR) investigation of the Cu{sub 3}Bi(SeO{sub 3}){sub 2}O{sub 2}Br planar metamagnet on the kagome lattice. Its mixed antiferromagnetic/ferromagnetic phase is stabilized in a finite range of applied fields around 0.8 T at low temperatures and is characterized by enhanced microwave absorption. The absorption signal is non-resonant and its boundaries correspond to two critical fields that determine the mixed phase. With decreasing temperature these increase like the sublattice magnetization of the antiferromagnetic phase and show no frequency dependence between 100 and 480 GHz. On the contrary, we find that the critical fields depend on the magnetic-field sweeping direction. In particular, the higher critical field, which corresponds to the transition from the mixed to the ferromagnetic phase, shows a pronounced hysteresis effect, while such a hysteresis is absent for the lower critical field. The observed hysteresis is enhanced at lower temperatures, which suggests that thermal fluctuations play an important role in destabilizing the highly absorbing mixed phase.

  10. Electron spin resonance insight into broadband absorption of the Cu3Bi(SeO3)2O2Br metamagnet

    Science.gov (United States)

    Zorko, A.; Gomilšek, M.; Pregelj, M.; Ozerov, M.; Zvyagin, S. A.; Ozarowski, A.; Tsurkan, V.; Loidl, A.; Zaharko, O.

    2016-05-01

    Metamagnets, which exhibit a transition from a low-magnetization to a high-magnetization state induced by the applied magnetic field, have recently been highlighted as promising materials for controllable broadband absorption. Here we show results of a multifrequency electron spin resonance (ESR) investigation of the Cu3Bi(SeO3)2O2Br planar metamagnet on the kagome lattice. Its mixed antiferromagnetic/ferromagnetic phase is stabilized in a finite range of applied fields around 0.8 T at low temperatures and is characterized by enhanced microwave absorption. The absorption signal is non-resonant and its boundaries correspond to two critical fields that determine the mixed phase. With decreasing temperature these increase like the sublattice magnetization of the antiferromagnetic phase and show no frequency dependence between 100 and 480 GHz. On the contrary, we find that the critical fields depend on the magnetic-field sweeping direction. In particular, the higher critical field, which corresponds to the transition from the mixed to the ferromagnetic phase, shows a pronounced hysteresis effect, while such a hysteresis is absent for the lower critical field. The observed hysteresis is enhanced at lower temperatures, which suggests that thermal fluctuations play an important role in destabilizing the highly absorbing mixed phase.

  11. Impedance-Based High Frequency Resonance Analysis of DFIG System in Weak Grids

    DEFF Research Database (Denmark)

    Song, Yipeng; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    The impedance-based model of Doubly Fed Induction Generator (DFIG) systems, including the rotor part (Rotor Side Converter (RSC) and induction machine), and the grid part (Grid Side Converter (GSC) and its output filter), has been developed for analysis and mitigation of the Sub- Synchronous...... Resonance (SSR). However, the High Frequency Resonance (HFR) of DFIG systems due to the impedance interaction between DFIG system and parallel compensated weak network is often overlooked. This paper thus investigates the impedance characteristics of DFIG systems for the analysis of HFR. The influences...... of the rotor speed variation, the machine mutual inductance and the digital control delay are evaluated. Two resonances phenomena are revealed, i.e., 1) the series HFR between the DFIG system and weak power grid; 2) the parallel HFR between the rotor part and the grid part of DFIG system. The impedance...

  12. Vibration energy harvester with low resonant frequency based on flexible coil and liquid spring

    Science.gov (United States)

    Wang, Y.; Zhang, Q.; Zhao, L.; Tang, Y.; Shkel, A.; Kim, E. S.

    2016-11-01

    This paper reports an electromagnetic vibration-energy harvester with low resonant frequency based on liquid spring composed of ferrofluid. Cylinder magnet array formed by four disc NdFeB magnets is suspended by ferrofluid in a laser-machined acrylic tube which is wrapped by flexible planar coil fabricated with microfabrication process. The magnet array and coil are aligned automatically by the ferrofluid. Restoring force when the magnet array is deviated from the balance position is proportional to the deviated distance, which makes the ferrofluid work as a liquid spring obeying Hook's law. Experimental results show that the electromagnetic energy harvester occupying 1.8 cc and weighing 5 g has a resonant frequency of 16 Hz and generates an induced electromotive force of Vrms = 2.58 mV (delivering 79 nW power into matched load of 21 Ω) from 3 g acceleration at 16 Hz.

  13. Electrical tuning of mechanical characteristics in qPlus sensor: Active Q and resonance frequency control

    International Nuclear Information System (INIS)

    Lee, Manhee; Hwang, Jong Geun; Jahng, Junghoon; Kim, QHwan; Noh, Hanaul; An, Sangmin; Jhe, Wonho

    2016-01-01

    We present an electrical feedback method for independent and simultaneous tuning of both the resonance frequency and the quality factor of a harmonic oscillator, the so called “qPlus” configuration of quartz tuning forks. We incorporate a feedback circuit with two electronic gain parameters into the original actuation-detection system, and systematically demonstrate the control of the original resonance frequency of 32 592 Hz from 32 572 Hz to 32 610 Hz and the original quality factor 952 from 408 up to 20 000. This tunable module can be used for enhancing and optimizing the oscillator performance in compliance with specifics of applications.

  14. A Stepwise Optimal Design of a Dynamic Vibration Absorber with Tunable Resonant Frequency

    Directory of Open Access Journals (Sweden)

    Jiejian DI

    2014-08-01

    Full Text Available A new kind of dynamic vibration absorber (DVA with tunable resonant frequency is presented. The kinematics differential equation about it is built and the stepwise optimization is performed. Firstly, four main system parameters involving the ratios of mass m, natural frequency f, vibration frequency g and damping z are solved by small-step-search method to obtain optimal steady state amplitude. Secondly, the sizing optimization of the dynamic vibration absorber is proceeded to search an optimal damping effect based on the optimal parameters (g, m, z, f. And such the damping effect is simulated in a flat structure, and the results show that the working frequency band and damping effect of the DVA after optimization won 20 % of the effect of ascension compared with that before optimization.

  15. First Mode Schumann Resonance Frequency Variation During a Solar Proton Event

    Directory of Open Access Journals (Sweden)

    Minu Sanfui

    2016-04-01

    Full Text Available A severe X-ray flare occurred on 06 - 07 March 2012 followed by a solar proton event (SPE. During this event we studied the variation in frequency of the first Schumann resonance (SR spectra mode from the recorded data over Kolkata (22.56°N, 88.5°E. The first mode frequency enhanced (~8.14 Hz, 3.85% during the solar X-ray bursts and immediately after its value decreased (~7.44 Hz, 5.13% during the proton event. The influences of SPE and X-ray bursts upon the SR frequency fluctuation are explained in terms of the changes in medium ionization, i.e., the change in dielectric property and two layer reflection height variation in the waveguide. The geomagnetic storm effect on the modification of this frequency variation occurring during that time is also considered.

  16. Spin-wave propagation and spin-polarized electron transport in single-crystal iron films

    Science.gov (United States)

    Gladii, O.; Halley, D.; Henry, Y.; Bailleul, M.

    2017-11-01

    The techniques of propagating spin-wave spectroscopy and current-induced spin-wave Doppler shift are applied to a 20-nm-thick Fe/MgO(001) film. The magnetic parameters extracted from the position of the spin-wave resonance peaks are very close to those tabulated for bulk iron. From the zero-current propagating wave forms, a group velocity of 4 km/s and an attenuation length of about 6 μ m are extracted for 1.6-μ m -wavelength spin wave at 18 GHz. From the measured current-induced spin-wave Doppler shift, we extract a surprisingly high degree of spin polarization of the current of 83 % , which constitutes the main finding of this work. This set of results makes single-crystalline iron a promising candidate for building devices utilizing high-frequency spin waves and spin-polarized currents.

  17. Vibration Mode Observation of Piezoelectric Disk-type Resonator by High Frequency Laser Doppler Vibrometer

    Science.gov (United States)

    Matsumura, Takeshi; Esashi, Masayoshi; Harada, Hiroshi; Tanaka, Shuji

    For future mobile phones based on cognitive radio technology, a compact multi-band RF front-end architecture is strongly required and an integrated multi-band RF filter bank is a key component in it. Contour-mode resonators are receiving increased attention for a multi-band filter solution, because its resonant frequency is mainly determined by its size and shape, which are defined by lithography. However, spurious responses including flexural vibration are also excited due to its thin structure. To improve resonator performance and suppress spurious modes, visual observation with a laser probe system is very effective. In this paper, we have prototyped a mechanically-coupled disk-array filter, which consists of a Si disk and 2 disk-type resonators of higher-order wine-glass mode, and observed its vibration modes using a high-frequency laser-Doppler vibrometer (UHF-120, Polytec, Inc.). As a result, it was confirmed that higher order wine-glass mode vibration included a compound displacement, and that its out-of-plane vibration amplitude was much smaller than other flexural spurious modes. The observed vibration modes were compared with FEM (Finite Element Method) simulation results. In addition, it was also confirmed that the fabrication error, e.g. miss-alignment, induced asymmetric vibration.

  18. Multi-cavity locally resonant structure with the low frequency and broad band-gaps

    Directory of Open Access Journals (Sweden)

    Jiulong Jiang

    2016-11-01

    Full Text Available A multi-cavity periodic structure with the characteristic of local resonance was proposed in the paper. The low frequency band-gap structure was comparatively analyzed by the finite element method (FEM and electric circuit analogy (ECA. Low frequency band-gap can be opened through the dual influence of the coupling’s resonance in the cavity and the interaction among the couplings between structures. Finally, the influence of the structural factors on the band-gap was analyzed. The results show that the structure, which is divided into three parts equally, has a broader effective band-gap below the frequency of 200 Hz. It is also proved that reducing the interval between unit structures can increase the intensity of the couplings among the structures. And in this way, the width of band-gap would be expanded significantly. Through the parameters adjustment, the structure enjoys a satisfied sound insulation effect below the frequency of 500Hz. In the area of low frequency noise reduction, the structure has a lot of potential applications.

  19. Low Noise Frequency Comb Sources Based on Synchronously Pumped Doubly Resonant Optical Parametric Oscillators

    Science.gov (United States)

    Wan, Chenchen

    Optical frequency combs are coherent light sources consist of thousands of equally spaced frequency lines. Frequency combs have achieved success in applications of metrology, spectroscopy and precise pulse manipulation and control. The most common way to generate frequency combs is based on mode-locked lasers which has the output spectrum of comb structures. To generate stable frequency combs, the output from mode-locked lasers need to be phase stabilized. The whole comb lines will be stabilized if the pulse train repetition rate corresponding to comb spacing and the pulse carrier envelope offset (CEO) frequency are both stabilized. The output from a laser always has fluctuations in parameters known as noise. In laser applications, noise is an important factor to limit the performance and often need to be well controlled. For example in precision measurement such as frequency metrology and precise spectroscopy, low laser intensity and phase noise is required. In mode-locked lasers there are different types of noise like intensity noise, pulse temporal position noise also known as timing jitter, optical phase noise. In term for frequency combs, these noise dynamics is more complex and often related. Understanding the noise behavior is not only of great interest in practical applications but also help understand fundamental laser physics. In this dissertation, the noise of frequency combs and mode-locked lasers will be studied in two projects. First, the CEO frequency phase noise of a synchronously pumped doubly resonant optical parametric oscillators (OPO) will be explored. This is very important for applications of the OPO as a coherent frequency comb source. Another project will focus on the intensity noise coupling in a soliton fiber oscillator, the finding of different noise coupling in soliton pulses and the dispersive waves generated from soliton perturbation can provide very practical guidance for low noise soliton laser design. OPOs are used to generate

  20. Process and equipment for automatic measurement of resonant frequencies in seismic detectors

    International Nuclear Information System (INIS)

    Fredriksson, O.A.; Thomas, E.L.

    1977-01-01

    This is a process for the automatic indication of the resonant frequency of one or more detector elements which have operated inside a geophysical data-gathering system. Geophones or hydrophones or groups of both instruments are to be understood as comprising the detector elements. The invention concerns the creation of a process and of equipment working with laboratory precision, although it can be used in the field. (orig./RW) [de