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Sample records for electric resonance

  1. Designing dielectric resonators on substrates: combining magnetic and electric resonances.

    PubMed

    van de Groep, J; Polman, A

    2013-11-01

    High-performance integrated optics, solar cells, and sensors require nanoscale optical components at the surface of the device, in order to manipulate, redirect and concentrate light. High-index dielectric resonators provide the possibility to do this efficiently with low absorption losses. The resonances supported by dielectric resonators are both magnetic and electric in nature. Combined scattering from these two can be used for directional scattering. Most applications require strong coupling between the particles and the substrate in order to enhance the absorption in the substrate. However, the coupling with the substrate strongly influences the resonant behavior of the particles. Here, we systematically study the influence of particle geometry and dielectric environment on the resonant behavior of dielectric resonators in the visible to near-IR spectral range. We show the key role of retardation in the excitation of the magnetic dipole (MD) mode, as well as the limit where no MD mode is supported. Furthermore, we study the influence of particle diameter, shape and substrate index on the spectral position, width and overlap of the electric dipole (ED) and MD modes. Also, we show that the ED and MD mode can selectively be enhanced or suppressed using multi-layer substrates. And, by comparing dipole excitation and plane wave excitation, we study the influence of driving field on the scattering properties. Finally, we show that the directional radiation profiles of the ED and MD modes in resonators on a substrate are similar to those of point-dipoles close to a substrate. Altogether, this work is a guideline how to tune magnetic and electric resonances for specific applications. PMID:24216852

  2. Frequency splitting of a multi-layered electric ring resonator

    NASA Astrophysics Data System (ADS)

    Kim, S. G.; Kim, K. H.; Jung, H. S.; Cho, H.; Choi, E. M.

    2011-07-01

    We present experimental results on the multilayering effects of an electric ring resonator. The electromagnetic response of the electric ring resonator is measured via a scattering matrix using a vector network analyzer at the X-band frequency. Structures of the electric ring resonator with up to four layers were tested and analyzed using commercial software. We demonstrate that, in an electric ring resonator, the electric and magnetic dipole polarization effect gives rise to resonance frequency splitting when the cell is multilayered.

  3. Electrical characteristics of a short RFQ resonator

    SciTech Connect

    Ben-Zvi, I.; Jain, A.; Wang, H. . Dept. of Physics); Lombardi, A. . Lab. Nazionale di Legnaro)

    1990-01-01

    Electrical characteristics of a short RFQ resonator of the four rod'' type have been studied by carrying out measurements on models and numerical simulations using the MAFIA codes. An empirical formula is obtained for the capacitance of vane-like electrodes in a four-rod RFQ resonator. It is shown that the electrode supports could account for a significant part of the total capacitance. This additional capacitance may change the circuit symmetry and give rise to a dipole component. This effect can be compensated by appropriate modifications of the support structure. The beam offset due to a dipole component is estimated. 6 refs., 4 figs., 1 tab.

  4. Compact electrically detected magnetic resonance setup

    SciTech Connect

    Eckardt, Michael Harneit, Wolfgang; Behrends, Jan; Münter, Detlef

    2015-04-15

    Electrically detected magnetic resonance (EDMR) is a commonly used technique for the study of spin-dependent transport processes in semiconductor materials and electro-optical devices. Here, we present the design and implementation of a compact setup to measure EDMR, which is based on a commercially available benchtop electron paramagnetic resonance (EPR) spectrometer. The electrical detection part uses mostly off-the-shelf electrical components and is thus highly customizable. We present a characterization and calibration procedure for the instrument that allowed us to quantitatively reproduce results obtained on a silicon-based reference sample with a “large-scale” state-of-the-art instrument. This shows that EDMR can be used in novel contexts relevant for semiconductor device fabrication like clean room environments and even glove boxes. As an application example, we present data on a class of environment-sensitive objects new to EDMR, semiconducting organic microcrystals, and discuss similarities and differences to data obtained for thin-film devices of the same molecule.

  5. Compact electrically detected magnetic resonance setup

    NASA Astrophysics Data System (ADS)

    Eckardt, Michael; Behrends, Jan; Münter, Detlef; Harneit, Wolfgang

    2015-04-01

    Electrically detected magnetic resonance (EDMR) is a commonly used technique for the study of spin-dependent transport processes in semiconductor materials and electro-optical devices. Here, we present the design and implementation of a compact setup to measure EDMR, which is based on a commercially available benchtop electron paramagnetic resonance (EPR) spectrometer. The electrical detection part uses mostly off-the-shelf electrical components and is thus highly customizable. We present a characterization and calibration procedure for the instrument that allowed us to quantitatively reproduce results obtained on a silicon-based reference sample with a "large-scale" state-of-the-art instrument. This shows that EDMR can be used in novel contexts relevant for semiconductor device fabrication like clean room environments and even glove boxes. As an application example, we present data on a class of environment-sensitive objects new to EDMR, semiconducting organic microcrystals, and discuss similarities and differences to data obtained for thin-film devices of the same molecule.

  6. Ultrafast electrical control of a resonantly driven single photon source

    SciTech Connect

    Cao, Y.; Bennett, A. J. Ellis, D. J. P.; Shields, A. J.; Farrer, I.; Ritchie, D. A.

    2014-08-04

    We demonstrate generation of a pulsed stream of electrically triggered single photons in resonance fluorescence, by applying high frequency electrical pulses to a single quantum dot in a p-i-n diode under resonant laser excitation. Single photon emission was verified, with the probability of multiple photon emission reduced to 2.8%. We show that despite the presence of charge noise in the emission spectrum of the dot, resonant excitation acts as a “filter” to generate narrow bandwidth photons.

  7. Comparison of nuclear electric resonance and nuclear magnetic resonance in integer and fractional quantum Hall states

    SciTech Connect

    Tomimatsu, Toru Shirai, Shota; Hashimoto, Katsushi Sato, Ken; Hirayama, Yoshiro

    2015-08-15

    Electric-field-induced nuclear resonance (NER: nuclear electric resonance) involving quantum Hall states (QHSs) was studied at various filling factors by exploiting changes in nuclear spins polarized at quantum Hall breakdown. Distinct from the magnetic dipole interaction in nuclear magnetic resonance, the interaction of the electric-field gradient with the electric quadrupole moment plays the dominant role in the NER mechanism. The magnitude of the NER signal strongly depends on whether electronic states are localized or extended. This indicates that NER is sensitive to the screening capability of the electric field associated with QHSs.

  8. Array of piezoelectric lateral electric field excited resonators.

    PubMed

    Borodina, I A; Zaitsev, B D; Teplykh, A A; Shikhabudinov, A M; Kuznetsova, I E

    2015-09-01

    An array containing two resonators placed on X-cut lithium niobate plate has been experimentally investigated. The resonator's lateral electric field was directed along the Y-crystallographic axis. It has been shown that stable resonance exists for a longitudinal acoustic wave propagating along the X-axis in the area between the electrodes. A layer of special damping coating was deposited around the resonators and on the part of electrodes to suppress parasitic oscillations induced mainly by Lamb waves. Frequency dependences of the real and imaginary parts of electric impedance/admittance were measured for every resonator to find resonant frequency and Q-factor with series and parallel resonances. The optimal values of width of electrode coating for every resonator were revealed which provide good resonance quality. The measurements of parameter S12, which characterizes a degree of acoustical coupling between the resonators, have shown its value to be higher than 50dB in the absolute value in all the cases considered. This means that the resonators under study are entirely acoustically decoupled. Thus it has been demonstrated that the damping layer not only provides a sufficiently good quality of every resonator's resonance, but it also assures their entire acoustical decoupling. PMID:26060097

  9. Eddy-current crack detection at frequencies approaching electrical resonance

    NASA Astrophysics Data System (ADS)

    Hughes, Robert R.; Dixon, Steve

    2014-02-01

    The effect of operating an absolute eddy-current (EC) probe at frequencies around its electrical resonance was investigated. A defect signal enhancement phenomenon was observed and characterised. Experimental tests were performed on notch defects in typical aerospace superalloys. An absolute mode EC probe was operated by sweeping through a range of frequencies, in the MHz range, encompassing the electrical resonance of the system. Resonance decoupling above defects results in a signal-to-noise ratio (SNR) peak, within a band of frequencies approaching resonance, of up to 3.7 times that measured at 1MHz. This near electrical resonance signal enhancement (NERSE) phenomenon poses the possibility for a simple operational approach method for improving the sensitivity of conventional eddy-current testing.

  10. The study of piezoelectric lateral-electric-field-excited resonator.

    PubMed

    Zaitsev, Boris; Kuznetsova, Iren; Shikhabudinov, Alexander; Teplykh, Andrey; Borodina, Irina

    2014-01-01

    The piezoelectric lateral-electric-field-excited resonator based on an X-cut lithium niobate plate has been investigated. Two rectangular electrodes were applied on one side of the plate so that the lateral electric field components were parallel to the crystallographic Y-axis and excited the longitudinal wave in the gap between the electrodes. The region around the electrodes was covered with a special absorbing varnish to suppress the spurious oscillations. The effect of the absorbing coating width on the resonant frequency and Q-factor of the lateral field-excited resonator was studied in detail with the series and parallel resonances for different width of the gap between the electrodes. As a result, we found experimentally the parameter regions of pure resonances and the boundaries of value variation for resonance frequency, Q-factor, and effective electromechanical coupling coefficient. PMID:24402903

  11. Electric-optic resonant phase modulator

    NASA Technical Reports Server (NTRS)

    Chen, Chien-Chung (Inventor); Robinson, Deborah L. (Inventor); Hemmati, Hamid (Inventor)

    1994-01-01

    An electro-optic resonant cavity is used to achieve phase modulation with lower driving voltages. Laser damage thresholds are inherently higher than with previously used integrated optics due to the utilization of bulk optics. Phase modulation is achieved at higher speeds with lower driving voltages than previously obtained with non-resonant electro-optic phase modulators. The instant scheme uses a data locking dither approach as opposed to the conventional sinusoidal locking schemes. In accordance with a disclosed embodiment, a resonant cavity modulator has been designed to operate at a data rate in excess of 100 Mbps. By carefully choosing the cavity finesse and its dimension, it is possible to control the pulse switching time to within 4 ns and to limit the required switching voltage to within 10 V. Experimentally, the resonant cavity can be maintained on resonance with respect to the input laser signal by monitoring the fluctuation of output intensity as the cavity is switched. This cavity locking scheme can be applied by using only the random data sequence, and without the need of additional dithering of the cavity. Compared to waveguide modulators, the resonant cavity has a comparable modulating voltage requirement. Because of its bulk geometry, resonant cavity modulator has the potential of accommodating higher throughput power. Furthermore, mode matching into a bulk device is easier and typically can be achieved with higher efficiency. On the other hand, unlike waveguide modulators which are essentially traveling wave devices, the resonant cavity modulator requires that the cavity be maintained in resonance with respect to the incoming laser signal. An additional control loop is incorporated into the modulator to maintain the cavity on resonance.

  12. Electrical Characterization of Microelectromechanical Silicon Carbide Resonators

    PubMed Central

    Chang, Wen-Teng; Zorman, Christian

    2008-01-01

    This manuscript describes the findings of a study to investigate the performance of SiC MEMS resonators with respect to resonant frequency and quality factor under a variety of testing conditions, including various ambient pressures, AC drive voltages, bias potentials and temperatures. The sample set included both single-crystal and polycrystalline 3C-SiC lateral resonators. The experimental results show that operation at reduced pressures increases the resonant frequency as damping due to the gas-rarefaction effect becomes significant. Both DC bias and AC drive voltages result in nonlinearities, but the AC drive voltage is more sensitive to noise. The AC voltage has a voltage coefficient of 1∼4ppm/V at a DC bias of 40V. The coefficient of DC bias is about -11ppm/V to - 21ppm/V for poly-SiC, which is more than a factor of two better than a similarly designed polysilicon resonator (-54 ppm/V). The effective stiffness of the resonator decreases (softens) as the bias potential is increased, but increases (hardens) as drive voltage increase when scan is from low to high frequency. The resonant frequency decreases slightly with increasing temperature, exhibiting a temperature coefficient of -22 ppm/°C, between 22°C and 60°C. The thermal expansion mismatch between the SiC device and the Si substrate could be a reason that thermal coefficient for these SiC resonators is about twofold higher than similar polysilicon resonators. However, the Qs appear to exhibit no temperature dependence in this range.

  13. Investigating electrical resonance in eddy-current array probes

    NASA Astrophysics Data System (ADS)

    Hughes, R.; Fan, Y.; Dixon, S.

    2016-02-01

    The sensitivity enhancing effects of eddy-current testing at frequencies close to electrical resonance are explored. Var-ied techniques exploiting the phenomenon, dubbed near electrical resonance signal enhancement (NERSE), were experimentally investigated to evaluate its potential exploitation for other interesting applications in aerospace materials, in particular its potential for boosting the sensitivity of standard ECT measurements. Methods for setting and controlling the typically unstable resonant frequencies of such systems are discussed. This research is funded by the EPSRC, via the Research Centre for Non-Destructive Evaluation RCNDE, and Rolls-Royce plc.

  14. A composite piezoelectric resonator with a lateral electric field

    NASA Astrophysics Data System (ADS)

    Zaitsev, B. D.; Shikhabudinov, A. M.; Borodina, I. A.; Teplykh, A. A.; Kuznetsova, I. E.

    2015-11-01

    A new method of suppressing parasitic oscillations in a piezoelectric resonator with excitation of the transverse electric field is proposed. The method is based on spatial separation of the high-frequency electric field of a source and the resonating piezoelectric plate by means of an air gap. In this case, the tangential components of field in the piezoelectric plate are practically not attenuated, while the normal components are significantly reduced. The method is implemented by means of a composite resonator consisting of a glass plate with rectangular electrodes, an air gap, and a plate of lithium niobate 1of 128 Y- X cut. It is shown that there is an optimal width of the air gap that provides a good quality of series and parallel resonance in a frequency range of 3-4 MHz with a maximum quality factor of ˜15000 in both cases.

  15. Extreme harmonic generation in electrically driven spin resonance.

    PubMed

    Stehlik, J; Schroer, M D; Maialle, M Z; Degani, M H; Petta, J R

    2014-06-01

    We report the observation of multiple harmonic generation in electric dipole spin resonance in an InAs nanowire double quantum dot. The harmonics display a remarkable detuning dependence: near the interdot charge transition as many as eight harmonics are observed, while at large detunings we only observe the fundamental spin resonance condition. The detuning dependence indicates that the observed harmonics may be due to Landau-Zener transition dynamics at anticrossings in the energy level spectrum. PMID:24949787

  16. Broadband electrically detected magnetic resonance using adiabatic pulses.

    PubMed

    Hrubesch, F M; Braunbeck, G; Voss, A; Stutzmann, M; Brandt, M S

    2015-05-01

    We present a broadband microwave setup for electrically detected magnetic resonance (EDMR) based on microwave antennae with the ability to apply arbitrarily shaped pulses for the excitation of electron spin resonance (ESR) and nuclear magnetic resonance (NMR) of spin ensembles. This setup uses non-resonant stripline structures for on-chip microwave delivery and is demonstrated to work in the frequency range from 4 MHz to 18 GHz. π pulse times of 50 ns and 70 μs for ESR and NMR transitions, respectively, are achieved with as little as 100 mW of microwave or radiofrequency power. The use of adiabatic pulses fully compensates for the microwave magnetic field inhomogeneity of the stripline antennae, as demonstrated with the help of BIR4 unitary rotation pulses driving the ESR transition of neutral phosphorus donors in silicon and the NMR transitions of ionized phosphorus donors as detected by electron nuclear double resonance (ENDOR). PMID:25828243

  17. Electrically Protected Resonant Exchange Qubits in Triple Quantum Dots

    NASA Astrophysics Data System (ADS)

    Taylor, J. M.; Srinivasa, V.; Medford, J.

    2013-08-01

    We present a modulated microwave approach for quantum computing with qubits comprising three spins in a triple quantum dot. This approach includes single- and two-qubit gates that are protected against low-frequency electrical noise, due to an operating point with a narrowband response to high frequency electric fields. Furthermore, existing double quantum dot advances, including robust preparation and measurement via spin-to-charge conversion, are immediately applicable to the new qubit. Finally, the electric dipole terms implicit in the high frequency coupling enable strong coupling with superconducting microwave resonators, leading to more robust two-qubit gates.

  18. Electrically protected resonant exchange qubits in triple quantum dots.

    PubMed

    Taylor, J M; Srinivasa, V; Medford, J

    2013-08-01

    We present a modulated microwave approach for quantum computing with qubits comprising three spins in a triple quantum dot. This approach includes single- and two-qubit gates that are protected against low-frequency electrical noise, due to an operating point with a narrowband response to high frequency electric fields. Furthermore, existing double quantum dot advances, including robust preparation and measurement via spin-to-charge conversion, are immediately applicable to the new qubit. Finally, the electric dipole terms implicit in the high frequency coupling enable strong coupling with superconducting microwave resonators, leading to more robust two-qubit gates. PMID:23952376

  19. 750 GeV diphoton resonance and electric dipole moments

    NASA Astrophysics Data System (ADS)

    Choi, Kiwoon; Im, Sang Hui; Kim, Hyungjin; Mo, Doh Young

    2016-09-01

    We examine the implication of the recently observed 750 GeV diphoton excess for the electric dipole moments of the neutron and electron. If the excess is due to a spin zero resonance which couples to photons and gluons through the loops of massive vector-like fermions, the resulting neutron electric dipole moment can be comparable to the present experimental bound if the CP-violating angle α in the underlying new physics is of O (10-1). An electron EDM comparable to the present bound can be achieved through a mixing between the 750 GeV resonance and the Standard Model Higgs boson, if the mixing angle itself for an approximately pseudoscalar resonance, or the mixing angle times the CP-violating angle α for an approximately scalar resonance, is of O (10-3). For the case that the 750 GeV resonance corresponds to a composite pseudo-Nambu-Goldstone boson formed by a QCD-like hypercolor dynamics confining at ΛHC, the resulting neutron EDM can be estimated with α ∼(750 GeV /ΛHC) 2θHC, where θHC is the hypercolor vacuum angle.

  20. Testing resonating vector strength: Auditory system, electric fish, and noise

    NASA Astrophysics Data System (ADS)

    Leo van Hemmen, J.; Longtin, André; Vollmayr, Andreas N.

    2011-12-01

    Quite often a response to some input with a specific frequency ν○ can be described through a sequence of discrete events. Here, we study the synchrony vector, whose length stands for the vector strength, and in doing so focus on neuronal response in terms of spike times. The latter are supposed to be given by experiment. Instead of singling out the stimulus frequency ν○ we study the synchrony vector as a function of the real frequency variable ν. Its length turns out to be a resonating vector strength in that it shows clear maxima in the neighborhood of ν○ and multiples thereof, hence, allowing an easy way of determining response frequencies. We study this "resonating" vector strength for two concrete but rather different cases, viz., a specific midbrain neuron in the auditory system of cat and a primary detector neuron belonging to the electric sense of the wave-type electric fish Apteronotus leptorhynchus. We show that the resonating vector strength always performs a clear resonance correlated with the phase locking that it quantifies. We analyze the influence of noise and demonstrate how well the resonance associated with maximal vector strength indicates the dominant stimulus frequency. Furthermore, we exhibit how one can obtain a specific phase associated with, for instance, a delay in auditory analysis.

  1. Electrical resonance and membrane currents in turtle cochlear hair cells.

    PubMed

    Art, J J; Crawford, A C; Fettiplace, R

    1986-01-01

    The electrical and mechanical properties of single hair cells from the turtle's cochlea were examined to investigate the basis of their electrical resonance. Receptor potentials were measured with intracellular micropipettes in the isolated basilar papilla. At the onset and termination of a step displacement of the ciliary bundle the receptor potential showed a damped oscillation reflecting the frequency selectivity of the cell. Resonance frequencies increased systematically from apex to base of the cochlea. Similar oscillations could be elicited by a current step injected through the recording electrode. Solitary hair cells enzymatically isolated from the papilla were investigated with the tight-seal whole-cell recording method. Cells retained their properties in response to current steps and had resonance frequencies between 10 and 350 Hz. In voltage clamp such cells displayed a large outward K+ current and an inward Ca2+ current both activated by depolarization from the resting potential. The relaxation time constant of the K+ current was inversely correlated with the resonance frequency of the cell, varying from 150 ms in the lowest frequency cells to less than 1 ms in the highest ones. It is argued that variation in the kinetics of this current is the major factor responsible for the range of resonance frequencies. In preparations of the isolated papilla a flexible glass fibre, attached to the tip of a ciliary bundle, was used to deliver constant force steps to the bundle and to monitor its displacement. Receptor potentials were simultaneously recorded. At the beginning and end of a force step towards the kinocilium, the bundle vibrated at a frequency which coincided with the electrical resonance frequency of the cell.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2426237

  2. Probing electric field control of magnetism using ferromagnetic resonance.

    PubMed

    Zhou, Ziyao; Trassin, Morgan; Gao, Ya; Gao, Yuan; Qiu, Diana; Ashraf, Khalid; Nan, Tianxiang; Yang, Xi; Bowden, S R; Pierce, D T; Stiles, M D; Unguris, J; Liu, Ming; Howe, Brandon M; Brown, Gail J; Salahuddin, S; Ramesh, R; Sun, Nian X

    2015-01-01

    Exchange coupled CoFe/BiFeO3 thin-film heterostructures show great promise for power-efficient electric field-induced 180° magnetization switching. However, the coupling mechanism and precise qualification of the exchange coupling in CoFe/BiFeO3 heterostructures have been elusive. Here we show direct evidence for electric field control of the magnetic state in exchange coupled CoFe/BiFeO3 through electric field-dependent ferromagnetic resonance spectroscopy and nanoscale spatially resolved magnetic imaging. Scanning electron microscopy with polarization analysis images reveal the coupling of the magnetization in the CoFe layer to the canted moment in the BiFeO3 layer. Electric field-dependent ferromagnetic resonance measurements quantify the exchange coupling strength and reveal that the CoFe magnetization is directly and reversibly modulated by the applied electric field through a ~180° switching of the canted moment in BiFeO3. This constitutes an important step towards robust repeatable and non-volatile voltage-induced 180° magnetization switching in thin-film multiferroic heterostructures and tunable RF/microwave devices. PMID:25631924

  3. Analysis of the line shape of electrically detected ferromagnetic resonance

    NASA Astrophysics Data System (ADS)

    Harder, M.; Cao, Z. X.; Gui, Y. S.; Fan, X. L.; Hu, C.-M.

    2011-08-01

    This work reviews and examines two particular issues related with the new technique of electrical detection of ferromagnetic resonance (FMR). This powerful technique has been broadly applied for studying magnetization and spin dynamics over the past ten years. The first issue is the relation and distinction between different mechanisms that give rise to a photovoltage via FMR in spintronic devices, and the second is the proper analysis of the FMR line shape, which has become the “Achilles heel” in interpreting experimental results, especially for either studying the spin pumping effect or quantifying spin Hall angles via the electrically detected FMR.

  4. Fano Resonance in an Electrically Driven Plasmonic Device.

    PubMed

    Vardi, Yuval; Cohen-Hoshen, Eyal; Shalem, Guy; Bar-Joseph, Israel

    2016-01-13

    We present an electrically driven plasmonic device consisting of a gold nanoparticle trapped in a gap between two electrodes. The tunneling current in the device generates plasmons, which decay radiatively. The emitted spectrum extends up to an energy that depends on the applied voltage. Characterization of the electrical conductance at low temperatures allows us to extract the voltage drop on each tunnel barrier and the corresponding emitted spectrum. In several devices we find a pronounced sharp asymmetrical dip in the spectrum, which we identify as a Fano resonance. Finite-difference time-domain calculations reveal that this resonance is due to interference between the nanoparticle and electrodes dipolar fields and can be conveniently controlled by the structural parameters. PMID:26717292

  5. Three-phase resonance bearing with an electric circuit

    NASA Astrophysics Data System (ADS)

    Viushkov, Iu. A.

    1980-02-01

    The paper deals with a magnetically suspended bearing employing a resonance electric circuit, intended for float-type navigation instruments. The bearing provides both suspension and rotation (required in some navigation devices) of the sensitive element. The rotational moment is produced by a rotating magnetic field generated by three electromagnets (arranged at angles of 120 degrees) connected in series to a three-phase electromotive source.

  6. Fano Resonance in an Electrically Driven Plasmonic Device

    NASA Astrophysics Data System (ADS)

    Vardi, Yuval; Cohen-Hoshen, Eyal; Shalem, Guy; Bar-Joseph, Israel

    Electrically driven plasmonic devices offer unique opportunities as a research tool and for practical applications. In such devices, current that flows across a metallic tunnel junction excites a plasmon, which gives rise to light emission. This local nature of the excitation allows access into ''dark'' modes, which are not easily excited by far field illumination. We present an electrically driven plasmonic device, based on a gold nanoparticle single-electron-transistor, and investigate the light emission due to the tunneling current. The applied voltage determines the emitted spectral lineshape, enables an excellent control of the plasmonic spectrum. We show that the use of this structure allows us to characterize the electrical properties of the two tunnel barriers, and determine their role in the light emission process. Furthermore, we find a Fano resonance, resulting from interference between the nanoparticle and electrodes dipoles. This resonance is seen due to the local nature of the excitation, and is manifested as a sharp asymmetrical spectral dip. We show that the spectral position of this resonance can be conveniently controlled by the design of the structural parameters. Such devices may be a step toward the realization of an on-chip nano-optical emitters and sensors.

  7. Extreme Harmonic Generation in Electrically Driven Spin Resonance

    NASA Astrophysics Data System (ADS)

    Stehlik, Jiri

    2015-03-01

    InAs nanowire double quantum dots offer a rich platform for studying single spin physics in a material with large spin-orbit (SO) coupling. The large SO coupling allows all electrical control of the electron spin through electric dipole spin resonance (EDSR). Here an oscillating electric field of frequency f displaces the electron wave function, while a magnetic field with strength B is applied. Spin rotations occur when the resonance condition hf = gμB B is met. Here g is the electron g-factor, h is Planck's constant, and μB is the Bohr magneton. We find that near zero interdot detuning efficient spin rotations also occur when hf = ngμB B , with n being an integer as large as 8 in our system. The harmonics feature a striking odd/even dependence. While the odd harmonics show an enhancement of the leakage current, the even harmonics show a reduction. In contrast, we do not observe any measurable harmonics at large detuning. We link the presence of harmonics with additional anti-crossings present in the level diagram. This implies that harmonics are the result of Landau-Zener transitions occurring at multiple anti-crossings. Recent theoretical work supports this conclusion. Research performed in collaboration with M. D. Schroer, M. Z. Maialle, M. H. Degani, and J. R. Petta. Research was supported by the Sloan and Packard Foundations, Army Research Office, DARPA QuEST and the NSF.

  8. Electrical switching of DNA monolayers investigated by surface plasmon resonance.

    PubMed

    Yang, Xiaohai; Wang, Qing; Wang, Kemin; Tan, Weihong; Yao, Jing; Li, Huimin

    2006-06-20

    The switching of DNA monolayers between a "lying" and a "standing" state initiated by applying electric field, and the subsequent DNA hybridization at different states were investigated in a contactless, label-free mode by surface plasmon resonance (SPR) technique. The results showed that the strength of the electric field and surface coverage could influence the switching of DNA monolayers. In addition, it was found that DNA hybridization efficiency could be enhanced or decreased when DNA probes stood straight up or lay flat on the gold surface, depending on the potential of the gold substrate. The enhancement of DNA hybridization efficiency reached the maximum when surface coverage reached 5.87 x 10(12) molecules/cm(2) and the potential of gold substrate was more negative than -0.7 V (versus ITO-coated glass). The research may be helpful for the construction of sensitive biosensors, biochips, and nanoscale electronic devices. PMID:16768490

  9. Tuning a resonant energy harvester using a generalized electrical load

    NASA Astrophysics Data System (ADS)

    Cammarano, A.; Burrow, S. G.; Barton, D. A. W.; Carrella, A.; Clare, L. R.

    2010-05-01

    A fundamental drawback of vibration-based energy harvesters is that they typically feature a resonant mass/spring mechanical system to amplify the small source vibrations; the limited bandwidth of the mechanical amplifier restricts the effectiveness of the energy harvester considerably. By extending the range of input frequencies over which a vibration energy harvester can generate useful power, e.g. through adaptive tuning, it is not only possible to open up a wider range of applications, such as those where the source frequency changes over time, but also possible to relax the requirements for precision manufacture or the need for mechanical adjustment in situ. In this paper, a vibration-based energy harvester connected to a generalized electrical load (containing both real and reactive impedance) is presented. It is demonstrated that the reactive component of the electrical load can be used to tune the harvester system to significantly increase the output power away from the resonant peak of the device. An analytical model of the system is developed, which includes non-ideal components arising from the physical implementation, and the results are confirmed by experiment. The - 3 dB (half-power) bandwidth of the prototype energy harvester is shown to be over three times greater when presented with an optimized load impedance compared to that for the same harvester presented with an optimized resistive only load.

  10. Magnetic Resonance Based Electrical Properties Tomography: A Review

    PubMed Central

    Zhang, Xiaotong; Liu, Jiaen

    2014-01-01

    Frequency-dependent electrical properties (EPs; conductivity and permittivity) of biological tissues provide important diagnostic information (e.g. tumor characterization), and also play an important role in quantifying radiofrequency (RF) coil induced Specific Absorption Rate (SAR) which is a major safety concern in high- and ultrahigh-field Magnetic Resonance Imaging (MRI) applications. Cross-sectional imaging of EPs has been pursued for decades. Recently introduced Electrical Properties Tomography (EPT) approaches utilize the measurable RF magnetic field induced by the RF coil in an MRI system to quantitatively reconstruct the EP distribution in vivo and non-invasively with a spatial resolution of a few millimeters or less. This paper reviews the Electrical Properties Tomography approach from its basic theory in electromagnetism to the state of the art research outcomes. Emphasizing on the imaging reconstruction methods rather than experimentation techniques, we review the developed imaging algorithms, validation results in physical phantoms and biological tissues, as well as their applications in in vivo tumor detection and subject-specific SAR prediction. Challenges for future research are also discussed. PMID:24803104

  11. Direct electrical-to-optical conversion and light modulation in micro whispering-gallery-mode resonators

    NASA Technical Reports Server (NTRS)

    Maleki, Lute (Inventor); Levi, Anthony F. J. (Inventor)

    2005-01-01

    Techniques for directly converting an electrical signal into an optical signal by using a whispering gallery mode optical resonator formed of a dielectric material that allows for direct modulation of optical absorption by the electrical signal.

  12. Ion Behavior in an Electrically Compensated Ion Cyclotron Resonance Trap

    PubMed Central

    Brustkern, Adam M.; Rempel, Don L.; Gross, Michael L.

    2010-01-01

    We recently described a new electrically compensated trap in FT ion cyclotron resonance mass spectrometry and developed a means of tuning traps of this general design. Here, we describe a continuation of that research by comparing the ion transient lifetimes and the resulting mass resolving powers and signal-to-noise (S/N) ratios that are achievable in the compensated vs. uncompensated modes of this trap. Transient lifetimes are ten times longer under the same conditions of pressure, providing improved mass resolving power and S/N ratios. The mass resolving power as a function of m/z is linear (log-log plot) and nearly equal to the theoretical maximum. Importantly, the ion cyclotron frequency as a function of ion number decreases linearly in accord with theory, unlike its behavior in the uncompensated mode. This linearity should lead to better control in mass calibration and increased mass accuracy than achievable in the uncompensated mode. PMID:21499521

  13. Asymmetric resonant exchange qubit under the influence of electrical noise

    NASA Astrophysics Data System (ADS)

    Russ, Maximilian; Burkard, Guido

    2015-06-01

    We investigate the influence of electrical charge noise on a resonant exchange (RX) qubit in a triple quantum dot. This RX qubit is a variation of the exchange-only spin qubit which responds to a narrow-band resonant frequency. Our noise model includes uncorrelated charge noise in each quantum dot giving rise to two independent (noisy) bias parameters ɛ and Δ . We calculate the energy splitting of the two qubit states as a function of these two bias detuning parameters to find "sweet spots," where the qubit is least susceptible to noise. Our investigation shows that such sweet spots exist within the low-bias regime, in which the bias detuning parameters have the same magnitude as the hopping parameters. The location of the sweet spots in the (ɛ ,Δ ) plane depends on the hopping strength and asymmetry between the quantum dots. In the regime of weak charge noise, we identify a new favorable operating regime for the RX qubit based on these sweet spots.

  14. Electrical resonance with voltage-gated ion channels: perspectives from biophysical mechanisms and neural electrophysiology

    PubMed Central

    Ge, Lin; Liu, Xiao-dong

    2016-01-01

    Electrical resonance, providing selective signal amplification at preferred frequencies, is a unique phenomenon of excitable membranes, which has been observed in the nervous system at the cellular, circuit and system levels. The mechanisms underlying electrical resonance have not been fully elucidated. Prevailing hypotheses attribute the resonance to voltage-gated ion channels on the membrane of single neurons. In this review, we follow this line of thinking to summarize and analyze the biophysical/molecular mechanisms, and also the physiological relevance of channel-mediated electrical resonance. PMID:26725736

  15. Electromagnetically induced transparency with large delay-bandwidth product induced by magnetic resonance near field coupling to electric resonance

    SciTech Connect

    Li, Hai-ming; Liu, Shao-bin Liu, Si-yuan; Zhang, Hai-feng; Bian, Bo-rui; Kong, Xiang-kun; Wang, Shen-yun

    2015-03-16

    In this paper, we numerically and experimentally demonstrate electromagnetically induced transparency (EIT)-like spectral response with magnetic resonance near field coupling to electric resonance. Six split-ring resonators and a cut wire are chosen as the bright and dark resonator, respectively. An EIT-like transmission peak located between two dips can be observed with incident magnetic field excitation. A large delay bandwidth product (0.39) is obtained, which has potential application in quantum optics and communications. The experimental results are in good agreement with simulated results.

  16. Scattering of core-shell nanowires with the interference of electric and magnetic resonances.

    PubMed

    Liu, Wei; Miroshnichenko, Andrey E; Oulton, Rupert F; Neshev, Dragomir N; Hess, Ortwin; Kivshar, Yuri S

    2013-07-15

    We study the scattering of normally incident waves by core-shell nanowires, which support both electric and magnetic resonances. Within such nanowires, for p-polarized incident waves, each electric resonance corresponds to two degenerate scattering channels while the magnetic resonance corresponds to only one channel. Consequently, when the electric dipole (ED) and magnetic dipole (MD) are tuned to overlap spectrally, the magnitude of the ED is twice that of the magnetic one, leading to a pair of angles of vanishing scattering. We further demonstrate that the scattering features of nanowires are polarization dependent, and vanishing scattering angles also can be induced by Fano resonances due to the interference of higher-order electric modes with the broad MD mode. PMID:23939129

  17. Graphene metallization of high-stress silicon nitride resonators for electrical integration.

    PubMed

    Lee, Sunwoo; Adiga, Vivekananda P; Barton, Robert A; van der Zande, Arend M; Lee, Gwan-Hyoung; Ilic, B Rob; Gondarenko, Alexander; Parpia, Jeevak M; Craighead, Harold G; Hone, James

    2013-09-11

    High stress stoichiometric silicon nitride resonators, whose quality factors exceed one million, have shown promise for applications in sensing, signal processing, and optomechanics. Yet, electrical integration of the insulating silicon nitride resonators has been challenging, as depositing even a thin layer of metal degrades the quality factor significantly. In this work, we show that graphene used as a conductive coating for Si3N4 membranes reduces the quality factor by less than 30% on average, which is minimal when compared to the effect of conventional metallization layers such as chromium or aluminum. The electrical integration of Si3N4-Graphene (SiNG) heterostructure resonators is demonstrated with electrical readout and electrostatic tuning of the frequency by up to 0.3% per volt. These studies demonstrate the feasibility of hybrid graphene/nitride mechanical resonators in which the electrical properties of graphene are combined with the superior mechanical performance of silicon nitride. PMID:23905749

  18. Theory of electrically controlled resonant tunneling spin devices

    NASA Technical Reports Server (NTRS)

    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.

  19. Fabry-Perot resonance enhanced electrically pumped random lasing from ZnO films

    NASA Astrophysics Data System (ADS)

    Ni, P. N.; Shan, C. X.; Wang, S. P.; Lu, Y. J.; Li, B. H.; Shen, D. Z.

    2015-12-01

    Fabry-Perot (F-P) resonance has been introduced into Au/MgO/ZnO structure in order to improve the performance of electrically pumped random lasing in this structure. It is found that the lasing threshold of this structure is significantly reduced by introducing the F-P resonance due to the better optical confinement. Meanwhile, this structure shows improved random lasing output characteristics with less random lasing modes and strong dominant output mode due to the gain competition process. The results demonstrate that introducing F-P resonance into the random media provides an effective strategy towards controllable, high performance electrically pumped random lasers.

  20. Electrically tunable Fano-type resonance of an asymmetric metal wire pair.

    PubMed

    Fu, Quanhong; Zhang, Fuli; Fan, Yuancheng; He, Xuan; Qiao, Tong; Kong, Botao

    2016-05-30

    We theoretically and experimentally investigate the electrically tunable Fano-type resonance of asymmetric metal wire pair loaded with varactor diodes. It is illustrated that Fano-type transmission spectrum with high quality factor Q appears as a result of interference between the dipole and quadrupole modes. The ohmic loss of series resistance in varactor diode makes major contribution to absorption. At the Fano-type resonance frequency, both the two metal wires exhibit the strongest electric resonance simultaneously, and the Fano-type resonance manifests a large group delay. As the bias voltage ranges from 0 V to 8 V, the Fano-type resonance frequency exhibits a prominent blueshift of 0.16 GHz and the transmission experiences a modulation with a modulation depth of 97%. PMID:27410096

  1. Composite modulation of Fano resonance in plasmonic microstructures by electric-field and microcavity

    SciTech Connect

    Zhang, Fan; Wu, Chenyun; Yang, Hong; Hu, Xiaoyong Gong, Qihuang

    2014-11-03

    Composite modulation of Fano resonance by using electric-field and microcavity simultaneously is realized in a plasmonic microstructure, which consists of a gold nanowire grating inserted into a Fabry-Perot microcavity composited of a liquid crystal layer sandwiched between two indium tin oxide layers. The Fano resonance wavelength varies with the applied voltage and the microcavity resonance. A large shift of 48 nm in the Fano resonance wavelength is achieved when the applied voltage is 20 V. This may provide a new way for the study of multi-functional integrated photonic circuits and chips based on plasmonic microstructures.

  2. Effects of combined apertures on the magnitudes of electric coupling coefficients of combline resonators

    NASA Astrophysics Data System (ADS)

    Pholele, T. M.; Chuma, J. M.

    2014-10-01

    The effects of differently positioned and combined apertures on the magnitudes of electric coupling coefficients of two identical combline resonators are analysed. Coupling coefficient, k-vertical symmetry provides greater negative coupling for apertures less than 50 % opening on the common wall. Combined apertures do not enhance electric coupling. The Γ aperture annihilates electric coupling, whereas T shaped aperture provides reduced negative coupling coefficients compared to single apertures that make up the combination.

  3. Electrical noise modulates perception of electrical pulses in humans: sensation enhancement via stochastic resonance.

    PubMed

    Iliopoulos, Fivos; Nierhaus, Till; Villringer, Arno

    2014-03-01

    Although noise is usually considered to be harmful for signal detection and information transmission, stochastic resonance (SR) describes the counterintuitive phenomenon of noise enhancing the detection and transmission of weak input signals. In mammalian sensory systems, SR-related phenomena may arise both in the peripheral and the central nervous system. Here, we investigate behavioral SR effects of subliminal electrical noise stimulation on the perception of somatosensory stimuli in humans. We compare the likelihood to detect near-threshold pulses of different intensities applied on the left index finger during presence vs. absence of subliminal noise on the same or an adjacent finger. We show that (low-pass) noise can enhance signal detection when applied on the same finger. This enhancement is strong for near-threshold pulses below the 50% detection threshold and becomes stronger when near-threshold pulses are applied as brief trains. The effect reverses at pulse intensities above threshold, especially when noise is replaced by subliminal sinusoidal stimulation, arguing for a peripheral direct current addition. Unfiltered noise applied on longer pulses enhances detection of all pulse intensities. Noise applied to an adjacent finger has two opposing effects: an inhibiting effect (presumably due to lateral inhibition) and an enhancing effect (most likely due to SR in the central nervous system). In summary, we demonstrate that subliminal noise can significantly modulate detection performance of near-threshold stimuli. Our results indicate SR effects in the peripheral and central nervous system. PMID:24353303

  4. Emulation of quantum mechanical billiards by electrical resonance circuits.

    PubMed

    Bengtsson, Olof; Larsson, Johan; Berggren, Karl-Fredrik

    2005-05-01

    We propose that a two-dimensional electric network may be used for fundamental studies of wave function properties, transport, and related statistics. Using Kirchhoff's current law and the j omega method we find that the network is analogous to a discretized Schrödinger equation for quantum billiards and dots. Thus complex electric potentials play the role of quantum mechanical wave functions. Ways of realizing the electric network are discussed briefly. The role of symmetries is outlined, and a direct way of selecting states with a given symmetry is presented. PMID:16089633

  5. Thermo-optically tuned photonic resonators with concurrent electrical connection and thermal isolation

    DOEpatents

    Lentine, Anthony L.; Kekatpure, Rohan Deodatta; Zortman, William A.; Savignon, Daniel J.

    2016-06-14

    A photonic resonator system is designed to use thermal tuning to adjust the resonant wavelength of each resonator in the system, with a separate tuning circuit associated with each resonator so that individual adjustments may be made. The common electrical ground connection between the tuning circuits is particularly formed to provide thermal isolation between adjacent resonators by including a capacitor along each return path to ground, where the presence of the capacitor's dielectric material provides the thermal isolation. The use of capacitively coupling necessarily requires the use of an AC current as an input to the heater element (conductor/resistor) of each resonator, where the RMS value of the AC signal is indicative of the amount of heat that is generated along the element and the degree of wavelength tuning that is obtained.

  6. Electrically tunable Dicke effect in a double-ring resonator

    SciTech Connect

    Cetin, A. E.; Muestecaplioglu, Oe. E.

    2010-04-15

    We study the finite-element method analysis of the Dicke effect using numerical simulations in an all-optical system of an optical waveguide side-coupled to two interacting ring resonators in a liquid crystal environment. The system is shown to exhibit all the signatures of the Dicke effect under active and reversible control by an applied voltage.

  7. Physics of a novel magnetic resonance and electrical impedance combination for breast cancer diagnosis

    NASA Astrophysics Data System (ADS)

    Kallergi, Maria; Heine, John J.; Wollin, Ernest

    2015-03-01

    A new technique is proposed and experimentally validated for breast cancer detection and diagnosis. The technique combines magnetic resonance with electrical impedance measurements and has the potential to increase the specificity of magnetic resonance mammography (MRM) thereby reducing false positive biopsy rates. The new magnetic resonance electrical impedance mammography (MREIM) adds a time varying electric field during a supplementary sequence to a standard MRM examination with an apparatus that is "invisible" to the patient. The applied electric field produces a current that creates an additional magnetic field with a component aligned with the bore magnetic field that can alter the native signal in areas of higher electrical conductivity. The justification for adding the electric field is that the electrical conductivity of cancerous breast tissue is approximately 3-40 times higher than normal breast tissue and, hence, conductivity of malignant tissue represents a known clinical disease biomarker. In a pilot study with custom-made phantoms and experimental protocols, it was demonstrated that MREIM can produce, as theoretically predicted, a detectable differential signal in areas of higher electrical conductivity (tumor surrogate regions); the evidence indicates that the differential signal is produced by the confluence of two different effects at full image resolution without gadolinium chelate contrast agent injection, without extraneous reconstruction techniques, and without cumbersome multi-positioned patient electrode configurations. This paper describes the theoretical model that predicts and explains the observed experimental results that were also confirmed by simulation studies.

  8. Auxiliary quasi-resonant dc tank electrical power converter

    DOEpatents

    Peng, Fang Z.

    2006-10-24

    An auxiliary quasi-resonant dc tank (AQRDCT) power converter with fast current charging, voltage balancing (or charging), and voltage clamping circuits is provided for achieving soft-switched power conversion. The present invention is an improvement of the invention taught in U.S. Pat. No. 6,111,770, herein incorporated by reference. The present invention provides faster current charging to the resonant inductor, thus minimizing delay time of the pulse width modulation (PWM) due to the soft-switching process. The new AQRDCT converter includes three tank capacitors or power supplies to achieve the faster current charging and minimize the soft-switching time delay. The new AQRDCT converter further includes a voltage balancing circuit to charge and discharge the three tank capacitors so that additional isolated power supplies from the utility line are not needed. A voltage clamping circuit is also included for clamping voltage surge due to the reverse recovery of diodes.

  9. Electrically detected magnetic resonance in a W-band microwave cavity

    SciTech Connect

    Lang, V.; Lo, C. C.; George, R. E.; Lyon, S. A.; Bokor, J.; Schenkel, T.; Ardavan, A.; Morton, J. J. L.

    2011-01-14

    We describe a low-temperature sample probe for the electrical detection of magnetic resonance in a resonant W-band (94 GHz) microwave cavity. The advantages of this approach are demonstrated by experiments on silicon field-effect transistors. A comparison with conventional low-frequency measurements at X-band (9.7 GHz) on the same devices reveals an up to 100-fold enhancement of the signal intensity. In addition, resonance lines that are unresolved at X-band are clearly separated in the W-band measurements. Electrically detected magnetic resonance at high magnetic fields and high microwave frequencies is therefore a very sensitive technique for studying electron spins with an enhanced spectral resolution and sensitivity.

  10. Measurement of a high electrical quality factor in a niobium resonator for a gravitational radiation detector

    NASA Technical Reports Server (NTRS)

    Folkner, W. M.; Moody, M. V.; Richard, J.-P.

    1989-01-01

    The mechanical and electrical quality factors of a 10-g niobium resonator were measured at 4.4 K and were found to be 8.1 x 10 to the 6th, and 3.8 x 10 to the 6th, respectively. The value for the electrical quality factor is high enough for a system operating at 50 mK at a sensitivity level of one phonon. The resonator's low damping properties make it suitable for use as a transducer for a cryogenic three-mode gravitational radiation detector. A practical design is given for the mounting of the resonator on a 2400-kg aluminum-bar detector. Projections are made for the sensitivity of a 2400-kg bar instrumented as a three-mode system with this resonator inductively coupled to a SQUID.

  11. Resonance Method of Electric-Dipole-Moment Measurements in Storage Rings

    SciTech Connect

    Orlov, Yuri F.; Morse, William M.; Semertzidis, Yannis K.

    2006-06-02

    A 'resonance method' of measuring the electric dipole moment (EDM) of nuclei in storage rings is described, based on two new ideas: (1) Oscillating particles' velocities in resonance with spin precession, and (2) alternately producing two sub-beams with different betatron tunes--one sub-beam to amplify and thus make it easier to correct ring imperfections that produce false signals imitating EDM signals, and the other to make the EDM measurement.

  12. RESONANCE METHOD OF ELECTRIC-DIPOLE-MOMENT MEASUREMENTS IN STORAGE RINGS.

    SciTech Connect

    ORLOV, Y.F.; MORSE, W.M.; SEMERTZIDIS, Y.K.

    2006-05-10

    A ''resonance method'' of measuring the electric dipole moment (EDM) of nuclei in storage rings is described, based on two new ideas: (1) Oscillating particles velocities in resonance with spin precession, and (2) alternately producing two sub-beams with different betatron tunes--one sub-beam to amplify and thus make it easier to correct ring imperfections that produce false signals imitating EDM signals, and the other to make the EDM measurement.

  13. Liquid sensor based on a piezoelectric lateral electric field-excited resonator.

    PubMed

    Zaitsev, Boris D; Shikhabudinov, Alexander M; Teplykh, Andrey A; Kuznetsova, Iren E

    2015-12-01

    The influence of viscous and conducting liquid on the characteristics of a piezoelectric lateral electric field-excited resonator based on the X-cut lithium niobate plate has been investigated. It has been found that the contact of a free surface of such resonator with conducting or viscous liquid leads to the substantial variation of its electrical impedance/admittance. The analysis has shown the modulus of electrical impedance or admittance at any frequency near the parallel or series resonance to be a parameter unambiguously associated with the conductivity or the viscosity. This parameter is more sensitive to the variation of the liquid conductivity or viscosity as compared to the widely used for this purpose resonant frequency whose variation area is essentially smaller. By this means the liquid conductivity and viscosity affects unambiguously on the change of electrical impedance and admittance modulus whose measurement at a fixed frequency should present no problem in practice. Consequently, the lateral field excited resonator we have described may be employed as a liquid conductivity and viscosity meter with an appropriate graduation. PMID:26216121

  14. Rashba coupling in three-dimensional wurtzite structure electron gas at electric-dipole spin resonance

    NASA Astrophysics Data System (ADS)

    Ungier, W.

    2014-05-01

    Theoretical description of Rashba effects in three-dimensional electron gas at electric-dipole spin resonance conditions is presented in the frame of conductivity tensor formalism. The details due to anisotropy of the effective mass tensor, as well as the Lande factor, are considered. The absorbed power is calculated for arbitrary orientation of the sample with respect to external fields: constant magnetic field and rf electric field. The differences between resonance signals in two- and three-dimensional electron gas are pointed out.

  15. Heat dissipation due to ferromagnetic resonance in a ferromagnetic metal monitored by electrical resistance measurement

    SciTech Connect

    Yamanoi, Kazuto; Yokotani, Yuki; Kimura, Takashi

    2015-11-02

    The heat dissipation due to the resonant precessional motion of the magnetization in a ferromagnetic metal has been investigated. We demonstrated that the temperature during the ferromagnetic resonance can be simply detected by the electrical resistance measurement of the Cu strip line in contact with the ferromagnetic metal. The temperature change of the Cu strip due to the ferromagnetic resonance was found to exceed 10 K, which significantly affects the spin-current transport. The influence of the thermal conductivity of the substrate on the heating was also investigated.

  16. Resonant tunneling of interacting electrons in an AC electric field

    SciTech Connect

    Elesin, V. F.

    2013-11-15

    The problem of the effect of electron-electron interaction on the static and dynamic properties of a double-barrier nanostructure (resonant tunneling diode (RTD)) is studied in terms of a coherent tunneling model, which includes a set of Schrödinger and Poisson equations with open boundary conditions. Explicit analytical expressions are derived for dc and ac potentials and reduced (active and reactive) currents in the quasi-classical approximation over a wide frequency range. These expressions are used to analyze the frequency characteristics of RTD. It is shown that the interaction can radically change the form of these expressions, especially in the case of a hysteretic I-V characteristic. In this case, the active current and the ac potentials can increase sharply at both low and high frequencies. For this increase to occur, it is necessary to meet quantum regime conditions and to choose a proper working point in the I-V characteristic of RTD. The possibility of appearance of specific plasma oscillations, which can improve the high-frequency characteristics of RTD, is predicted. It is found that the active current can be comparable with the resonant dc current of RTD.

  17. Giant electric field enhancement in split ring resonators featuring nanometer-sized gaps.

    PubMed

    Bagiante, S; Enderli, F; Fabiańska, J; Sigg, H; Feurer, T

    2015-01-01

    Today's pulsed THz sources enable us to excite, probe, and coherently control the vibrational or rotational dynamics of organic and inorganic materials on ultrafast time scales. Driven by standard laser sources THz electric field strengths of up to several MVm(-1) have been reported and in order to reach even higher electric field strengths the use of dedicated electric field enhancement structures has been proposed. Here, we demonstrate resonant electric field enhancement structures, which concentrate the incident electric field in sub-diffraction size volumes and show an electric field enhancement as high as ~14,000 at 50 GHz. These values have been confirmed through a combination of near-field imaging experiments and electromagnetic simulations. PMID:25623373

  18. Real-time analysis of mechanical and electrical resonances with open-source sound card software

    NASA Astrophysics Data System (ADS)

    Makan, G.; Kopasz, K.; Gingl, Z.

    2014-01-01

    We present an easily reproducible, open-source, sound card based experimental set-up to support transfer function measurement. Our system is able to visualize the signals of mechanical and electrical resonances and their spectra in real time. We give a brief description of the system, and show some examples of electrical and mechanical resonance experiments that are supported by the system. The theoretical background, experimental set-up, component selection and digital signal processing are all discussed, and more detailed information (building instructions, software download) is provided on a dedicated web page (www.noise.inf.u-szeged.hu/edudev/RealTimeAnalysisOfResonances/). The experimental set-up can support the undergraduate and graduate education of students of physics, physics education and engineering by means of experimental demonstrations and laboratory exercises. The very low cost, high efficiency and transparent system provides a scalable experimental environment that can be easily built in several instances.

  19. Oscillations emerging from noise-driven steady state in networks with electrical synapses and subthreshold resonance

    PubMed Central

    Tchumatchenko, Tatjana; Clopath, Claudia

    2014-01-01

    Oscillations play a critical role in cognitive phenomena and have been observed in many brain regions. Experimental evidence indicates that classes of neurons exhibit properties that could promote oscillations, such as subthreshold resonance and electrical gap junctions. Typically, these two properties are studied separately but it is not clear which is the dominant determinant of global network rhythms. Our aim is to provide an analytical understanding of how these two effects destabilize the fluctuation-driven state, in which neurons fire irregularly, and lead to an emergence of global synchronous oscillations. Here we show how the oscillation frequency is shaped by single neuron resonance, electrical and chemical synapses.The presence of both gap junctions and subthreshold resonance are necessary for the emergence of oscillations. Our results are in agreement with several experimental observations such as network responses to oscillatory inputs and offer a much-needed conceptual link connecting a collection of disparate effects observed in networks. PMID:25405458

  20. Gradient-based Magnetic Resonance Electrical Properties Imaging of Brain Tissues

    PubMed Central

    Liu, Jiaen; Zhang, Xiaotong; Schmitter, Sebastian; Van de Moortele, Pierre-Francois; He, Bin

    2015-01-01

    Electrical properties tomography (EPT) holds promise for noninvasively mapping at high spatial resolution the electrical conductivity and permittivity of biological tissues in vivo using a magnetic resonance imaging (MRI) scanner. In the present study, we developed a novel gradient-based EPT approach with greatly improved tissue boundary reconstruction and largely elevated robustness against measurement noise compared to existing techniques. Using a 7 Tesla MRI system, we report high-quality in vivo human brain electrical property images with refined structural details, which can potentially merit clinical diagnosis (such as cancer detection) and high-field MRI applications (local SAR quantification) in the future. PMID:25571378

  1. Resonant transport and electrostatic effects in single-molecule electrical junctions

    NASA Astrophysics Data System (ADS)

    Brooke, Carly; Vezzoli, Andrea; Higgins, Simon J.; Zotti, Linda A.; Palacios, J. J.; Nichols, Richard J.

    2015-05-01

    In this contribution we demonstrate structural control over a transport resonance in HS (CH2)n[1 ,4 -C6H4] (CH2)nSH (n =1 , 3, 4, 6) metal-molecule-metal junctions, fabricated and tested using the scanning tunneling microscopy-based I (z ) method. The Breit-Wigner resonance originates from one of the arene π -bonding orbitals, which sharpens and moves closer to the contact Fermi energy as n increases. Varying the number of methylene groups thus leads to a very shallow decay of the conductance with the length of the molecule. We demonstrate that the electrical behavior observed here can be straightforwardly rationalized by analyzing the effects caused by the electrostatic balance created at the metal-molecule interface. Such resonances offer future prospects in molecular electronics in terms of controlling charge transport over longer distances, and also in single-molecule conductance switching if the resonances can be externally gated.

  2. Biological sensor based on a lateral electric field-excited resonator.

    PubMed

    Zaitsev, Boris D; Kuznetsova, Iren E; Shikhabudinov, Alexander M; Ignatov, Oleg V; Guliy, Olga I

    2012-05-01

    This paper describes a biological sensor based on a lateral electric field-excited resonator using an X-cut lithium niobate plate. Its potential was shown through the example of biological interaction between bacterial cells and specific bacteriophages. The detection was based on the analysis of the measured real and imaginary parts of electrical impedance for a resonator loaded by the biological suspension under study. It has been shown that the sensor is sensitive to specific interactions between bacterial cells and specific bacteriophages in a pure state as well as in the presence of extraneous microflora. The degree of electrical impedance variation resulting from the biological interaction depends on the numbers of phage particles and bacteria cells. The sensor may be used not only for the qualitative analysis of bacteria but also for their quantitative detection. PMID:22622981

  3. Noninvasive Imaging of Head-Brain Conductivity Profiles Using Magnetic Resonance Electrical Impedance Imaging

    PubMed Central

    Zhang, Xiaotong; Yan, Dandan; Zhu, Shanan; He, Bin

    2008-01-01

    Magnetic resonance electrical impedance tomography (MREIT) is a recently introduced non-invasive conductivity imaging modality, which combines the magnetic resonance current density imaging (CDI) and the traditional electrical impedance tomography (EIT) techniques. MREIT is aimed at providing high spatial resolution images of electrical conductivity, by avoiding solving the well-known ill-posed problem in the traditional EIT. In this paper, we review our research activities in MREIT imaging of head-brain tissue conductivity profiles. We have developed several imaging algorithms and conducted a series of computer simulations for MREIT imaging of the head and brain tissues. Our work suggests MREIT brain imaging may become a useful tool in imaging conductivity distributions of the brain and head. PMID:18799394

  4. High resolution in-operando microimaging of solar cells with pulsed electrically-detected magnetic resonance.

    PubMed

    Katz, Itai; Fehr, Matthias; Schnegg, Alexander; Lips, Klaus; Blank, Aharon

    2015-02-01

    The in-operando detection and high resolution spatial imaging of paramagnetic defects, impurities, and states becomes increasingly important for understanding loss mechanisms in solid-state electronic devices. Electron spin resonance (ESR), commonly employed for observing these species, cannot meet this challenge since it suffers from limited sensitivity and spatial resolution. An alternative and much more sensitive method, called electrically-detected magnetic resonance (EDMR), detects the species through their magnetic fingerprint, which can be traced in the device's electrical current. However, until now it could not obtain high resolution images in operating electronic devices. In this work, the first spatially-resolved electrically-detected magnetic resonance images (EDMRI) of paramagnetic states in an operating real-world electronic device are provided. The presented method is based on a novel microwave pulse sequence allowing for the coherent electrical detection of spin echoes in combination with powerful pulsed magnetic-field gradients. The applicability of the method is demonstrated on a device-grade 1-μm-thick amorphous silicon (a-Si:H) solar cell and an identical device that was degraded locally by an electron beam. The degraded areas with increased concentrations of paramagnetic defects lead to a local increase in recombination that is mapped by EDMRI with ∼20-μm-scale pixel resolution. The novel approach presented here can be widely used in the nondestructive in-operando three-dimensional characterization of solid-state electronic devices with a resolution potential of less than 100 nm. PMID:25557860

  5. High resolution in-operando microimaging of solar cells with pulsed electrically-detected magnetic resonance

    NASA Astrophysics Data System (ADS)

    Katz, Itai; Fehr, Matthias; Schnegg, Alexander; Lips, Klaus; Blank, Aharon

    2015-02-01

    The in-operando detection and high resolution spatial imaging of paramagnetic defects, impurities, and states becomes increasingly important for understanding loss mechanisms in solid-state electronic devices. Electron spin resonance (ESR), commonly employed for observing these species, cannot meet this challenge since it suffers from limited sensitivity and spatial resolution. An alternative and much more sensitive method, called electrically-detected magnetic resonance (EDMR), detects the species through their magnetic fingerprint, which can be traced in the device's electrical current. However, until now it could not obtain high resolution images in operating electronic devices. In this work, the first spatially-resolved electrically-detected magnetic resonance images (EDMRI) of paramagnetic states in an operating real-world electronic device are provided. The presented method is based on a novel microwave pulse sequence allowing for the coherent electrical detection of spin echoes in combination with powerful pulsed magnetic-field gradients. The applicability of the method is demonstrated on a device-grade 1-μm-thick amorphous silicon (a-Si:H) solar cell and an identical device that was degraded locally by an electron beam. The degraded areas with increased concentrations of paramagnetic defects lead to a local increase in recombination that is mapped by EDMRI with ∼20-μm-scale pixel resolution. The novel approach presented here can be widely used in the nondestructive in-operando three-dimensional characterization of solid-state electronic devices with a resolution potential of less than 100 nm.

  6. Bipolaron formation in organic solar cells observed by pulsed electrically detected magnetic resonance.

    PubMed

    Behrends, J; Schnegg, A; Lips, K; Thomsen, E A; Pandey, A K; Samuel, I D W; Keeble, D J

    2010-10-22

    We report the observation of a spin-dependent dark transport current, exhibiting spin coherence at room temperature, in a π-conjugated polymer-fullerene blend using pulsed electrically detected magnetic resonance. The resonance at g = 2.0028(3) is due to polarons in the polymer, and exhibits spin locking at high microwave fields. The presence of an excess of fullerene, and the operating voltage (1 V) used, suppresses negative polaron formation in the polymer. It is concluded that spin-dependent transport is due to the formation of positive bipolarons. PMID:21231063

  7. A study of the optimum draft of multiple resonance power buoys for maximizing electric power production

    NASA Astrophysics Data System (ADS)

    Kweon, Hyuck-Min; Cho, Hong-Yeon; Cho-Hyoung, ii

    2014-12-01

    To maximize electric power production using wave energy extractions from resonance power buoys, the maximum motion displacement spectra of the buoys can primarily be obtained under a given wave condition. In this study, wave spectra observed in shoaling water were formulated. Target resonance frequencies were established from the arithmetic means of modal frequency bands and the peak frequencies. The motion characteristics of the circular cylindrical power buoys with corresponding drafts were then calculated using numerical models without considering PTO damping force. Results showed that the heave motions of the power buoys in shoaling waters with insufficient drafts produced greater amplification effects than those in deep seas with sufficient drafts.

  8. Optimization of a Tunable Piezoelectric Resonator Using Phononic Crystals with Periodic Electrical Boundary Conditions

    NASA Astrophysics Data System (ADS)

    Ponge, Marie-Fraise; Dubus, Bertrand; Granger, Christian; Vasseur, Jérôme; Thi, Mai Pham; Hladky-Hennion, Anne-Christine

    Piezoelectric phononic crystals with periodic short-circuit conditions exhibit Bragg band gaps. They are used to design a Fabry-Perot cavity. The design of the device enables a modification of cavity length by a spatial shift of electrical boundary conditions. The resonator is thus tunable and a frequency shift is obtained. An analytical model based on a transfer matrix formalism is used to model longitudinal wave propagation inside the structure. Cavity length, phononic crystal and transducer position are optimized to increase resonance and antiresonance frequency shifts as well as coupling coefficient. Numerical and experimental results are presented and discussed.

  9. Electrically detected magnetic resonance signal from iron contaminated Czochralski silicon crystal

    NASA Astrophysics Data System (ADS)

    Mchedlidze, T.; Matsumoto, K.

    1998-04-01

    The electrical detection of magnetic resonance (EDMR) measurement, a detection method for the spin-dependent recombination, was applied to characterize iron contaminated silicon samples grown by the Czochralski method. The observed signal was different than previously reported electron paramagnetic resonance signals from defects in silicon. In addition, as the signal was not detected from similarly contaminated samples prepared from floating zone grown silicon crystal, we propose that the signal originates from defects containing iron and oxygen, namely, from iron decorated oxide precipitates. The dependency of EDMR signal on different experimental conditions (microwave power, illumination intensity, and temperature) were studied.

  10. Hyperfine interaction mediated electric-dipole spin resonance: the role of frequency modulation

    NASA Astrophysics Data System (ADS)

    Li, Rui

    2016-05-01

    The electron spin in a semiconductor quantum dot can be coherently controlled by an external electric field, an effect called electric-dipole spin resonance (EDSR). Several mechanisms can give rise to the EDSR effect, among which there is a hyperfine mechanism, where the spin-electric coupling is mediated by the electron–nucleus hyperfine interaction. Here, we investigate the influence of frequency modulation (FM) on the spin-flip efficiency. Our results reveal that FM plays an important role in the hyperfine mechanism. Without FM, the electric field almost cannot flip the electron spin the spin-flip probability is only about 20%. While under FM, the spin-flip probability can be improved to approximately 70%. In particular, we find that the modulation amplitude has a lower bound, which is related to the width of the fluctuated hyperfine field.

  11. Spin transport, magnetoresistance, and electrically detected magnetic resonance in amorphous hydrogenated silicon nitride

    NASA Astrophysics Data System (ADS)

    Mutch, Michael J.; Lenahan, Patrick M.; King, Sean W.

    2016-08-01

    We report on a study of spin transport via electrically detected magnetic resonance (EDMR) and near-zero field magnetoresistance (MR) in silicon nitride films. Silicon nitrides have long been important materials in solid state electronics. Although electronic transport in these materials is not well understood, electron paramagnetic resonance studies have identified a single dominating paramagnetic defect and have also provided physical and chemical descriptions of the defects, called K centers. Our EDMR and MR measurements clearly link the near-zero field MR response to the K centers and also indicate that K center energy levels are approximately 3.1 eV above the a-SiN:H valence band edge. In addition, our results suggest an approach for the study of defect mediated spin-transport in inorganic amorphous insulators via variable electric field and variable frequency EDMR and MR which may be widely applicable.

  12. Spectroscopic Observation of Resonant Electric Dipole-Dipole Interactions between Cold Rydberg Atoms

    NASA Astrophysics Data System (ADS)

    Afrousheh, K.; Bohlouli-Zanjani, P.; Vagale, D.; Mugford, A.; Fedorov, M.; Martin, J. D.

    2004-11-01

    Resonant electric dipole-dipole interactions between cold Rydberg atoms were observed using microwave spectroscopy. Laser-cooled 85Rb atoms in a magneto-optical trap were optically excited to 45d5/2 Rydberg states using a pulsed laser. A microwave pulse transferred a fraction of these Rydberg atoms to the 46p3/2 state. A second microwave pulse then drove atoms in the 45d5/2 state to the 46d5/2 state, and was used as a probe of interatomic interactions. The spectral width of this two-photon probe transition was found to depend on the presence of the 46p3/2 atoms, and is due to the resonant electric dipole-dipole interaction between 45d5/2 and 46p3/2 Rydberg atoms.

  13. Dephasing due to Nuclear Spins in Large-Amplitude Electric Dipole Spin Resonance

    NASA Astrophysics Data System (ADS)

    Chesi, Stefano; Yang, Li-Ping; Loss, Daniel

    2016-02-01

    We analyze effects of the hyperfine interaction on electric dipole spin resonance when the amplitude of the quantum-dot motion becomes comparable or larger than the quantum dot's size. Away from the well-known small-drive regime, the important role played by transverse nuclear fluctuations leads to a Gaussian decay with characteristic dependence on drive strength and detuning. A characterization of spin-flip gate fidelity, in the presence of such additional drive-dependent dephasing, shows that vanishingly small errors can still be achieved at sufficiently large amplitudes. Based on our theory, we analyze recent electric dipole spin resonance experiments relying on spin-orbit interactions or the slanting field of a micromagnet. We find that such experiments are already in a regime with significant effects of transverse nuclear fluctuations and the form of decay of the Rabi oscillations can be reproduced well by our theory.

  14. Electrically driven flexural resonant modes in symmetrically electroded X-cut and Z-cut quartz discs.

    PubMed

    Chen, P J

    1988-01-01

    While it is well known that flexural mechanical resonant modes can be electrically driven in specimens of quartz and other piezoelectric materials by the judicious choice of electrode patterns, specific experimental data, based on simultaneous interferometric observations of opposite surface points, are presented to show that symmetrically electroded X-cut and Z-cut quartz discs exhibit flexural resonant modes of quite large amplitudes. These resonances are not accompanied by detectable electrical disturbances in the AC-drive circuits. The existence of these modes is demonstrated for an X-cut quartz disc, and specific resonant modes of a Z-cut quartz disc are characterized in detail. PMID:18290131

  15. Dark and bright mode hybridization: From electric to magnetic Fano resonances

    NASA Astrophysics Data System (ADS)

    Panaro, S.; De Angelis, F.; Toma, A.

    2016-01-01

    The excitation of plasmonic Fano resonances leads to a dual advantage in nano-photonics, in terms of local field enhancement and far-field spectral selectivity. Nevertheless, a remarkable challenge related to the hybridization between bright and dark plasmonic modes, i.e. between the two elements cooperating to the Fano resonance generation, consists in the sub-wavelength activation of dark modes via near-field channel. In this regard, strongly coupled plasmonic nano-assemblies are ideal systems providing a highly efficient way towards their excitation. Here, we analyze two trimer nano-architectures supporting respectively electric and magnetic Fano resonances. The different approaches employed for describing the two systems highlighted the role that the near-field coupling and the LSPs de-phasing separately play in the Fano hybridization phenomena.

  16. Electrically tunable Dirac-point resonance induced by a nanomagnet absorbed on the topological insulator surface

    NASA Astrophysics Data System (ADS)

    Wang, Rui-Qiang; Sheng, L.; Yang, M.; Wang, Baigeng; Xing, D. Y.

    2015-06-01

    We investigate the effect of spin-inelastic scattering of Dirac electrons off a high-spin nanomagnet adsorbed on a topological insulator (TI) surface, in which transitions of the nanomagnet between its internal magnetic levels are taken into account, beyond the classic spin theory. It is found that the presence of magnetic anisotropy of nanomagnets can result in a Dirac-point resonance peak in local density of states. It can significantly modify the topologically protected Dirac surface-state spectrum at the Dirac point, quite different from previously reported low-energy resonances. Furthermore, we propose to tune electrically the appearance of the Dirac-point resonance peak and its height by use of the spin-flip torque effect. This provides an approach to engineer the Dirac cone and tune the Dirac electron properties on the TI surface in the absence of an external magnetic field.

  17. On the electrically detected cyclotron resonance of holes in silicon nanostructures

    SciTech Connect

    Bagraev, N. T. Gets, D. S.; Danilovsky, E. Yu.; Klyachkin, L. E.; Malyarenko, A. M.

    2013-04-15

    The cyclotron resonance in semiconductor nanostructures is electrically detected for the first time without an external cavity, a source, and a detector of microwave radiation. An ultranarrow p-Si quantum well on an n-Si (100) surface confined by superconducting heavily boron-doped {delta}-shaped barriers is used as the object of investigation and provides microwave generation within the framework of the nonstationary Josephson effect. The cyclotron resonance is detected upon the presence of a microcavity, which is incorporated into the quantum-well plane, by measuring the longitudinal magnetoresistance under conditions of stabilization of the source-drain current. The cyclotron-resonance spectra and their angular dependences measured in a low magnetic field identify small values of the effective mass of light and heavy holes in various 2D subbands due to the presence of edge channels with a high mobility of carriers.

  18. General model with experimental validation of electrical resonant frequency tuning of electromagnetic vibration energy harvesters

    NASA Astrophysics Data System (ADS)

    Zhu, Dibin; Roberts, Stephen; Mouille, Thomas; Tudor, Michael J.; Beeby, Stephen P.

    2012-10-01

    This paper presents a general model and its experimental validation for electrically tunable electromagnetic energy harvesters. Electrical tuning relies on the adjustment of the electrical load so that the maximum output power of the energy harvester occurs at a frequency which is different from the mechanical resonant frequency of the energy harvester. Theoretical analysis shows that for this approach to be feasible the electromagnetic vibration energy harvester’s coupling factor must be maximized so that its resonant frequency can be tuned with the minimum decrease of output power. Two different-sized electromagnetic energy harvesters were built and tested to validate the model. Experimentally, the micro-scale energy harvester has a coupling factor of 0.0035 and an untuned resonant frequency of 70.05 Hz. When excited at 30 mg, it was tuned by 0.23 Hz by changing its capacitive load from 0 to 4000 nF its effective tuning range is 0.15 Hz for a capacitive load variation from 0 to 1500 nF. The macro-scale energy harvester has a coupling factor of 552.25 and an untuned resonant frequency of 95.1 Hz and 95.5 Hz when excited at 10 mg and 25 mg, respectively. When excited at 10 mg, it was tuned by 3.8 Hz by changing its capacitive load from 0 to 1400 nF it has an effective tuning range of 3.5 Hz for a capacitive load variation from 0 to 1200 nF. When excited at 25 mg, its resonant frequency was tuned by 4.2 Hz by changing its capacitive load from 0 to 1400 nF it has an effective tuning range of about 5 Hz. Experimental results were found to agree with the theoretical analysis to within 10%.

  19. Optical resonances in electrically charged particles and their relation to the Drude model

    NASA Astrophysics Data System (ADS)

    Kocifaj, Miroslav; Kundracik, František; Videen, Gorden; Yuffa, Alex J.; Klačka, Jozef

    2016-07-01

    The Drude model is conventionally used to explain the average motion of electrons in typical material. In this paper, we analyze the individual terms of the Drude model in order to uncover their influence on the scattering properties of small particles. Namely, a query on whether resonance enhancement is due to optical effects or the conductivity model. This query arose from our earlier theoretical and numerical experiments and still remains unresolved today. We show that certain resonance features are caused primarily by the interaction of the electromagnetic wave with the excess electric charge on the particles. Furthermore, we show that the role of a conductivity model is limited to only establishing the relative importance of the inertial moment of the carriers and the viscous drag forces. For frequencies ω ≤kB T / ℏ , the viscous forces only cause minor damping effects and the change in the peak resonance (along with its amplitude) are caused by the electric and inertial forces. These forces dominate because the viscous forces quickly decay with decreasing temperature. In order to demonstrate the optical behavior of charged water droplets, we construct a Mie-series solution with modified boundary conditions that properly account for the excess electric charge on the droplets. Our solution explains the weak scattering enhancement for frequencies far beyond the resonance, and it also predicts an absorption resonance edge in the long-wavelength limit. Our findings are not only useful to theoreticians who focus on the individual parameters such as the viscous term in the Drude model and/or search for better surface conductivity models, but also to experimentalists who gather as much data as possible in order to ascertain how the numerically determined optical properties compare with the experimental measurements.

  20. Development of Short Electrical Pulses in a Schottky Line Periodically Loaded with Resonant Tunneling Diodes

    NASA Astrophysics Data System (ADS)

    Essimbi, B. Z.; Jäger, D.

    2012-06-01

    The characteristics of a Schottky line periodically loaded with resonant tunneling diodes (RTDs) are discussed for the development of short electrical pulses. RTDs act as electronic switches and exhibit a pronounced N-shaped I-V characteristic even at millimetre wave frequencies. The dynamics of the line is reduced to an extended KdV equation. These dynamics are considered both within the method of perturbation and the numerical integration of the transmission equation of the line.

  1. Electrical short pulses generation using a resonant tunneling diode nonlinear transmission line

    NASA Astrophysics Data System (ADS)

    Essimbi, B. Z.; Jäger, D.

    2012-03-01

    In this paper, the generation of short electrical pulses based on nonlinear active wave propagation effects along the resonant tunneling diode transmission line is studied. The principle of operation is discussed and it is shown by computer experiments that an input rectangular pulse as well as a sinusoidal input signal can be converted into a set of output spikes, suitable for A/D conversion at millimeter wave frequencies.

  2. Electrically-detected magnetic resonance in semiconductor nanostructures inserted in microcavities

    NASA Astrophysics Data System (ADS)

    Bagraev, Nikolay; Danilovskii, Eduard; Gehlhoff, Wolfgang; Gets, Dmitrii; Klyachkin, Leonid; Kudryavtsev, Andrey; Kuzmin, Roman; Malyarenko, Anna; Mashkov, Vladimir; Romanov, Vladimir

    2013-12-01

    We present the first findings of the new electrically-detected electron spin resonance technique (EDESR), which reveal the point defects in the ultra-narrow silicon quantum wells (Si-QW) confined by the superconductor δ-barriers. This technique allows the ESR identification without application of an external cavity, as well as a high frequency source and recorder, and with measuring the only response of the magnetoresistance caused by the microcavities embedded in the Si-QW plane.

  3. Numerical Model of Lateral Electric Field Excited Resonator on Piezoelectric Plate Bordered with Viscous and Conductive Liquid

    NASA Astrophysics Data System (ADS)

    Teplykh, Andrey; Zaitsev, Boris; Kuznetsova, Iren

    The numerical method of calculation of characteristics of lateral electric field excited resonator contacting with viscous and conducting liquid and results of these calculations are described. The method based on finite element analysis allows to find the distribution of mechanical and electrical fields in piezoelectric plate and liquid and to calculate the frequency dependencies of electrical impedance and admittance of resonator. It has been shown that values of real parts of impedance and admittance on resonant frequencies unambiguously correspond to viscosity and conductivity of liquid.

  4. Electrical actuation and readout in a nanoelectromechanical resonator based on a laterally suspended zinc oxide nanowire

    NASA Astrophysics Data System (ADS)

    Khaderbad, Mrunal A.; Choi, Youngjin; Hiralal, Pritesh; Aziz, Atif; Wang, Nan; Durkan, Colm; Thiruvenkatanathan, Pradyumna; Amaratunga, Gehan A. J.; Ramgopal Rao, V.; Seshia, Ashwin A.

    2012-01-01

    In this paper, we present experimental results describing enhanced readout of the vibratory response of a doubly clamped zinc oxide (ZnO) nanowire employing a purely electrical actuation and detection scheme. The measured response suggests that the piezoelectric and semiconducting properties of ZnO effectively enhance the motional current for electromechanical transduction. For a doubly clamped ZnO nanowire resonator with radius ˜10 nm and length ˜1.91 µm, a resonant frequency around 21.4 MHz is observed with a quality factor (Q) of ˜358 in vacuum. A comparison with the Q obtained in air (˜242) shows that these nano-scale devices may be operated in fluid as viscous damping is less significant at these length scales. Additionally, the suspended nanowire bridges show field effect transistor (FET) characteristics when the underlying silicon substrate is used as a gate electrode or using a lithographically patterned in-plane gate electrode. Moreover, the Young’s modulus of ZnO nanowires is extracted from a static bending test performed on a nanowire cantilever using an AFM and the value is compared to that obtained from resonant frequency measurements of electrically addressed clamped-clamped beam nanowire resonators.

  5. The importance of multi-level Rydberg interaction in electric field tuned Förster resonances

    NASA Astrophysics Data System (ADS)

    Kondo, Jorge; Booth, Donald; Gonçalves, Luis; Shaffer, James; Marcassa, Luis

    2016-05-01

    Many-body physics has been investigated in ultracold Rydberg atom systems, mainly because important parameters, such as density and interaction strength, can be controlled. Several puzzling experimental observations on Förster resonances have been associated to many-body effects, usually by comparison to complex theoretical models. In this work, we investigate the dc electric field dependence of 2 Förster resonant processes in ultracold 85 Rb, 37D5 / 2 + 37D5 / 2 --> 35 L(L = O , Q) + 39P3 / 2 , as a function of the atomic density in an optical dipole trap. At low densities, the 39 P yield as a function of electric field exhibits resonances. With increasing density, the linewidths increase until the peaks merge. Even under these extreme conditions, where many-body effects were expected to play a role, the 39 P population depends quadratically on the total Rydberg atom population. In order to explain our results, we implement a theoretical model which takes into account the multi-level character of the interactions and Rydberg atom blockade process using only atom pair interactions. The comparison between the experimental data and the model is very good, suggesting that the Förster resonant processes are dominated by 2-body interactions. This work is supported by FAPESP, AFOSR, NSF, INCT-IQ and CNPq.

  6. Electro-optic ring resonators in integrated optics for miniature electric field sensors

    NASA Astrophysics Data System (ADS)

    Ruege, Alexander Charles

    This dissertation addresses two important aspects regarding the sensing of radio-frequency electromagnetic fields using integrated optical ring resonator devices. The first topic involves the theoretical design, fabrication and demonstration of a new field sensor based on electro-optically (EO) active integrated optical ring resonators. The second topic addresses the problem of enhancing the response from a single-mode ring resonator of a given ring waveguide loss through modifications in the device geometry. The miniature integrated optical EO ring resonator sensor consists of low-dielectric constant polymers, is metal-free and is supported by a thin, flexible substrate. The low-invasive platform is achieved through the development of a new fabrication process. The waveguide cores of the devices are constructed of polycarbonate doped with the EO chromophore Disperse Red 1 and are poled using the contact poling method. The measured loaded quality factors of the poled EO rings are between 15,600 and 18,900. The fields emanating from a microstrip resonator circuit at 3.9 GHz are measured. It is determined that the measured modulation from the four-ring linear array is largest when the optical wavelength is biased on the steep slopes of the resonance lineshapes as theoretically predicted. Using electric field values obtained from electromagnetic simulations of the microstrip circuit, the EO coefficient is 0.72 pm/V. The sensitivity for electric fields in free-space field is 142.2 V / (m Hz0.5). The sensitivity is obtained for an off-resonance optical power of -9 dBm at an optical wavelength near 1550 nm, a photoreceiver conversion gain of 900 V/W, and a system impedance of 50 ohm. Also, sensing from asymmetric lineshapes due to the bistable effect in the ring resonators is also demonstrated. This EO field sensing demonstration is the first reported using EO ring resonator sensors built on a metal-free flexible integrated optics platform. The second part of this

  7. A Tuning Method for Electrically Compensated Ion Cyclotron Resonance Mass Spectrometer Traps

    PubMed Central

    Brustkern, Adam M.; Rempel, Don L.; Gross, Michael L.

    2010-01-01

    We describe a method for tuning electrically compensated ion cyclotron resonance (ICR) traps by tracking the observed cyclotron frequency of an ion cloud at different oscillation mode amplitudes. Although we have used this method to tune the compensation voltages of a custom-built electrically compensated trap, the approach is applicable to other designs that incorporate electrical compensation. To evaluate the effectiveness of tuning, we examined the frequency shift as a function of cyclotron orbit size at different z-mode oscillation amplitudes. The cyclotron frequencies varied by ~ 12 ppm for ions with low z-mode oscillation amplitudes compared to those with high z-mode amplitudes. This frequency difference decreased to ~1 ppm by one iteration of trap tuning. PMID:20060743

  8. Electric field effect on optical harmonic generation at the exciton resonances in GaAs

    NASA Astrophysics Data System (ADS)

    Brunne, D.; Lafrentz, M.; Pavlov, V. V.; Pisarev, R. V.; Rodina, A. V.; Yakovlev, D. R.; Bayer, M.

    2015-08-01

    An electric field applied to a semiconductor reduces its crystal symmetry and modifies its electronic structure which is expected to result in changes of the linear and nonlinear response to optical excitation. In GaAs, we observe experimentally strong electric field effects on the optical second (SHG) and third (THG) harmonic generation. The SHG signal for the laser-light k vector parallel to the [001] crystal axis is symmetry forbidden in the electric-dipole approximation, but can be induced by an applied electric field in the vicinity of the 1 s exciton energy. Surprisingly, the THG signal, which is allowed in this geometry, is considerably reduced by the electric field. We develop a theory which provides good agreement with the experimental data. In particular, it shows that the optical nonlinearities for the 1 s exciton resonance are modified in an electric field by the Stark effect, which mixes the 1 s and 2 p exciton states of opposite parity. This mixing acts in opposite way on the SHG and THG processes, as it leads to the appearance of forbidden SHG in (001)-oriented GaAs and decreases the crystallographic THG.

  9. Electrostatic Generation of Bulk Acoustic Waves and Electrical Parameters of Si-MEMS Resonators.

    PubMed

    Dulmet, Bernard; Ivan, Mihaela Eugenia; Ballandras, Sylvain

    2016-02-01

    This paper proposes an analytical approach to model the generation of bulk acoustic waves in an electrostatically excited silicon MEMS structure, as well as its electromechanical response in terms of static and dynamic displacements, electromechanical coupling, and motional current. The analysis pertains to the single-port electrostatic drive of trapped-energy thickness-extensional (TE) modes in thin plates. Both asymmetric single-side and symmetric double-side electrostatic gap configurations are modeled. Green's function is used to describe the characteristic of the static displacement of the driven surface of the structure versus the dc bias voltage, which allows us to determine the electrical response of the resonator. Optical and electrical characterizations have been performed on resonator samples operating at 10.3 MHz on the fundamental of TE mode under single-side electrostatic excitation. The various figures of merit depend on the dc bias voltage. Typical values of 9000 for the Q-factor, and of 10(-5) for the electromechanical coupling factor k(2) have been obtained with [Formula: see text] for [Formula: see text]-thick gaps. Here-considered modes have a typical temperature coefficients of frequency (TCF) close to -30 ppm/(°)C. We conclude that the practical usability of such electrostatically excited bulk acoustic waves (BAW) resonators essentially depends on the efficiency of the compensation of feed-through capacitance. PMID:26642450

  10. Electrically detected magnetic resonance modeling and fitting: An equivalent circuit approach

    SciTech Connect

    Leite, D. M. G.; Batagin-Neto, A.; Nunes-Neto, O.; Gómez, J. A.; Graeff, C. F. O.

    2014-01-21

    The physics of electrically detected magnetic resonance (EDMR) quadrature spectra is investigated. An equivalent circuit model is proposed in order to retrieve crucial information in a variety of different situations. This model allows the discrimination and determination of spectroscopic parameters associated to distinct resonant spin lines responsible for the total signal. The model considers not just the electrical response of the sample but also features of the measuring circuit and their influence on the resulting spectral lines. As a consequence, from our model, it is possible to separate different regimes, which depend basically on the modulation frequency and the RC constant of the circuit. In what is called the high frequency regime, it is shown that the sign of the signal can be determined. Recent EDMR spectra from Alq{sub 3} based organic light emitting diodes, as well as from a-Si:H reported in the literature, were successfully fitted by the model. Accurate values of g-factor and linewidth of the resonant lines were obtained.

  11. Guided resonances on lithium niobate for extremely small electric field detection investigated by accurate sensitivity analysis.

    PubMed

    Qiu, Wentao; Ndao, Abdoulaye; Lu, Huihui; Bernal, Maria-Pilar; Baida, Fadi Issam

    2016-09-01

    We present a theoretical study of guided resonances (GR) on a thin film lithium niobate rectangular lattice photonic crystal by band diagram calculations and 3D Finite Difference Time Domain (FDTD) transmission investigations which cover a broad range of parameters. A photonic crystal with an active zone as small as 13μm×13μm×0.7μm can be easily designed to obtain a resonance Q value in the order of 1000. These resonances are then employed in electric field (E-field) sensing applications exploiting the electro optic (EO) effect of lithium niobate. A local field factor that is calculated locally for each FDTD cell is proposed to accurately estimate the sensitivity of GR based E-field sensor. The local field factor allows well agreement between simulations and reported experimental data therefore providing a valuable method in optimizing the GR structure to obtain high sensitivities. When these resonances are associated with sub-picometer optical spectrum analyzer and high field enhancement antenna design, an E-field probe with a sensitivity of 50 μV/m could be achieved. The results of our simulations could be also exploited in other EO based applications such as EEG (Electroencephalography) or ECG (Electrocardiography) probe and E-field frequency detector with an 'invisible' probe to the field being detected etc. PMID:27607627

  12. Dynamics of firing patterns, synchronization and resonances in neuronal electrical activities: experiments and analysis

    NASA Astrophysics Data System (ADS)

    Lu, Qishao; Gu, Huaguang; Yang, Zhuoqin; Shi, Xia; Duan, Lixia; Zheng, Yanhong

    2008-12-01

    Recent advances in the experimental and theoretical study of dynamics of neuronal electrical firing activities are reviewed. Firstly, some experimental phenomena of neuronal irregular firing patterns, especially chaotic and stochastic firing patterns, are presented, and practical nonlinear time analysis methods are introduced to distinguish deterministic and stochastic mechanism in time series. Secondly, the dynamics of electrical firing activities in a single neuron is concerned, namely, fast-slow dynamics analysis for classification and mechanism of various bursting patterns, one- or two-parameter bifurcation analysis for transitions of firing patterns, and stochastic dynamics of firing activities (stochastic and coherence resonances, integer multiple and other firing patterns induced by noise, etc.). Thirdly, different types of synchronization of coupled neurons with electrical and chemical synapses are discussed. As noise and time delay are inevitable in nervous systems, it is found that noise and time delay may induce or enhance synchronization and change firing patterns of coupled neurons. Noise-induced resonance and spatiotemporal patterns in coupled neuronal networks are also demonstrated. Finally, some prospects are presented for future research. In consequence, the idea and methods of nonlinear dynamics are of great significance in exploration of dynamic processes and physiological functions of nervous systems.

  13. Reconstruction of apparent orthotropic conductivity tensor image using magnetic resonance electrical impedance tomography

    NASA Astrophysics Data System (ADS)

    Sajib, Saurav Z. K.; Kim, Ji Eun; Jeong, Woo Chul; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

    2015-03-01

    Magnetic resonance electrical impedance tomography visualizes current density and/or conductivity distributions inside an electrically conductive object. Injecting currents into the imaging object along at least two different directions, induced magnetic flux density data can be measured using a magnetic resonance imaging scanner. Without rotating the object inside the scanner, we can measure only one component of the magnetic flux density denoted as Bz. Since the biological tissues such as skeletal muscle and brain white matter show strong anisotropic properties, the reconstruction of anisotropic conductivity tensor is indispensable for the accurate observations in the biological systems. In this paper, we propose a direct method to reconstruct an axial apparent orthotropic conductivity tensor by using multiple Bz data subject to multiple injection currents. To investigate the anisotropic conductivity properties, we first recover the internal current density from the measured Bz data. From the recovered internal current density and the curl-free condition of the electric field, we derive an over-determined matrix system for determining the internal absolute orthotropic conductivity tensor. The over-determined matrix system is designed to use a combination of two loops around each pixel. Numerical simulations and phantom experimental results demonstrate that the proposed algorithm stably determines the orthotropic conductivity tensor.

  14. Reconstruction of apparent orthotropic conductivity tensor image using magnetic resonance electrical impedance tomography

    SciTech Connect

    Sajib, Saurav Z. K.; Kim, Ji Eun; Jeong, Woo Chul; Kim, Hyung Joong; Woo, Eung Je; Kwon, Oh In

    2015-03-14

    Magnetic resonance electrical impedance tomography visualizes current density and/or conductivity distributions inside an electrically conductive object. Injecting currents into the imaging object along at least two different directions, induced magnetic flux density data can be measured using a magnetic resonance imaging scanner. Without rotating the object inside the scanner, we can measure only one component of the magnetic flux density denoted as B{sub z}. Since the biological tissues such as skeletal muscle and brain white matter show strong anisotropic properties, the reconstruction of anisotropic conductivity tensor is indispensable for the accurate observations in the biological systems. In this paper, we propose a direct method to reconstruct an axial apparent orthotropic conductivity tensor by using multiple B{sub z} data subject to multiple injection currents. To investigate the anisotropic conductivity properties, we first recover the internal current density from the measured B{sub z} data. From the recovered internal current density and the curl-free condition of the electric field, we derive an over-determined matrix system for determining the internal absolute orthotropic conductivity tensor. The over-determined matrix system is designed to use a combination of two loops around each pixel. Numerical simulations and phantom experimental results demonstrate that the proposed algorithm stably determines the orthotropic conductivity tensor.

  15. Hyperfine interaction mediated electric-dipole spin resonance: The role of the frequency modulation

    NASA Astrophysics Data System (ADS)

    Li, Rui

    The electron spin in semiconductor quantum dot can be coherently controlled by an external electric field, an effect called electric-dipole spin resonance (EDSR). There are several mechanisms underlie the EDSR, among which there is a hyperfine mechanism, where the spin-electric coupling is mediated by the electron-nucleus hyperfine interaction. Here, we investigate the influence of the frequency modulation (FM) to the driving electric field on the spin-flip efficiency. Our results reveal that FM plays an important role in the hyperfine mechanism. Without FM, the electric field almost cannot flip the electron spin, the spin-flip probability is only about 20%. While under the FM, the spin-flip probability can be improved approximately to 70%. Especially, we find there is a lower bound on the modulation amplitude, which is related to the width of the hyperfine field fluctuation of the nuclear spins. This work is supported by National Natural Science Foundation of China Grant No. 11404020 and Postdoctoral Science Foundation of China Grant No. 2014M560039.

  16. Resonant electric dipole-dipole interactions between cold Rydberg atoms in a magnetic field

    NASA Astrophysics Data System (ADS)

    Afrousheh, Kourosh; Bohlouli-Zanjani, Parisa; Carter, Jeffery; Mugford, Ashton; Martin, James D. D.

    2006-05-01

    Laser cooled Rb atoms were optically excited to 46d5/2 Rydberg states. A microwave pulse transferred a fraction of the atoms to the 47p3/2 Rydberg state. The resonant electric dipole-dipole interactions between atoms in these two states were probed using the linewidth of the two-photon microwave transitions 46d5/2 -- 47d5/2. The presence of a weak magnetic field (roughly 1 G) reduced the observed line broadening, indicating that the interaction is suppressed by the field. The field removes some of the energy degeneracies responsible foe the resonant interaction, and this is the basis for a quantitative model of the resulting suppression. A technique for the calibration of magnetic field strengths using the 34s1/2 -- 34p1/2 one-photon transition is also presented.

  17. Resonant electric dipole-dipole interactions between cold Rydberg atoms in a magnetic field

    NASA Astrophysics Data System (ADS)

    Afrousheh, K.; Bohlouli-Zanjani, P.; Carter, J. D.; Mugford, A.; Martin, J. D. D.

    2006-06-01

    Laser-cooled Rb85 atoms were optically excited to 46d5/2 Rydberg states. A microwave pulse transferred a fraction of the atoms to the 47p3/2 Rydberg state. The resonant electric dipole-dipole interactions between atoms in these two states were probed using the linewidth of the two-photon microwave transition 46d5/2-47d5/2 . The presence of a weak magnetic field ≈0.5G reduced the observed line broadening, indicating that the interaction is suppressed by the field. The field removes some of the energy degeneracies responsible for the resonant interaction, and this is the basis for a quantitative model of the resulting suppression. A technique for the calibration of magnetic field strengths using the 34s1/2-34p1/2 one-photon transition is also presented.

  18. Mode jumping of split-ring resonator metamaterials controlled by high-permittivity BST and incident electric fields

    PubMed Central

    Fu, Xiaojian; Zeng, Xinxi; Cui, Tie Jun; Lan, Chuwen; Guo, Yunsheng; Zhang, Hao Chi; Zhang, Qian

    2016-01-01

    We investigate the resonant modes of split-ring resonator (SRR) metamaterials that contain high-permittivity BST block numerically and experimentally. We observe interesting mode-jumping phenomena from the BST-included SRR absorber structure as the excitation wave is incident perpendicularly to the SRR plane. Specifically, when the electric field is parallel to the SRR gap, the BST block in the gap will induce a mode jumping from the LC resonance to plasmonic resonance (horizontal electric-dipole mode), because the displacement current excited by the Mie resonance in the dielectric block acts as a current channel in the gap. When the electric field is perpendicular to the gap side, the plasmonic resonance mode (vertical electric-dipole mode) in SRR changes to two joint modes contributed simultaneously by the back layer, SRR and BST block, as a result of connected back layer and SRR layer by the displacement current in the BST dielectric block. Based on the mode jumping effect as well as temperature and electric-field dependent dielectric constant, the BST-included SRR metamaterials may have great potentials for the applications in electromagnetic switches and widely tunable metamaterial devices. PMID:27502844

  19. Mode jumping of split-ring resonator metamaterials controlled by high-permittivity BST and incident electric fields.

    PubMed

    Fu, Xiaojian; Zeng, Xinxi; Cui, Tie Jun; Lan, Chuwen; Guo, Yunsheng; Zhang, Hao Chi; Zhang, Qian

    2016-01-01

    We investigate the resonant modes of split-ring resonator (SRR) metamaterials that contain high-permittivity BST block numerically and experimentally. We observe interesting mode-jumping phenomena from the BST-included SRR absorber structure as the excitation wave is incident perpendicularly to the SRR plane. Specifically, when the electric field is parallel to the SRR gap, the BST block in the gap will induce a mode jumping from the LC resonance to plasmonic resonance (horizontal electric-dipole mode), because the displacement current excited by the Mie resonance in the dielectric block acts as a current channel in the gap. When the electric field is perpendicular to the gap side, the plasmonic resonance mode (vertical electric-dipole mode) in SRR changes to two joint modes contributed simultaneously by the back layer, SRR and BST block, as a result of connected back layer and SRR layer by the displacement current in the BST dielectric block. Based on the mode jumping effect as well as temperature and electric-field dependent dielectric constant, the BST-included SRR metamaterials may have great potentials for the applications in electromagnetic switches and widely tunable metamaterial devices. PMID:27502844

  20. Mode jumping of split-ring resonator metamaterials controlled by high-permittivity BST and incident electric fields

    NASA Astrophysics Data System (ADS)

    Fu, Xiaojian; Zeng, Xinxi; Cui, Tie Jun; Lan, Chuwen; Guo, Yunsheng; Zhang, Hao Chi; Zhang, Qian

    2016-08-01

    We investigate the resonant modes of split-ring resonator (SRR) metamaterials that contain high-permittivity BST block numerically and experimentally. We observe interesting mode-jumping phenomena from the BST-included SRR absorber structure as the excitation wave is incident perpendicularly to the SRR plane. Specifically, when the electric field is parallel to the SRR gap, the BST block in the gap will induce a mode jumping from the LC resonance to plasmonic resonance (horizontal electric-dipole mode), because the displacement current excited by the Mie resonance in the dielectric block acts as a current channel in the gap. When the electric field is perpendicular to the gap side, the plasmonic resonance mode (vertical electric-dipole mode) in SRR changes to two joint modes contributed simultaneously by the back layer, SRR and BST block, as a result of connected back layer and SRR layer by the displacement current in the BST dielectric block. Based on the mode jumping effect as well as temperature and electric-field dependent dielectric constant, the BST-included SRR metamaterials may have great potentials for the applications in electromagnetic switches and widely tunable metamaterial devices.

  1. Advances in series resonant inverter technology and its effect on spacecraft employing electric propulsion

    NASA Technical Reports Server (NTRS)

    Robson, R. R.

    1982-01-01

    The efficiency of transistorized Series Resonant Inverters (SRIs), which is higher than that of silicon-controlled rectifier alternatives, reduces spacecraft radiator requirements by 40% and may eliminate the need for heat pipes on 30-cm ion thruster systems. Recently developed 10- and 25-kW inverters have potential applications in gas thrusters, and represent the first spaceborne SRI designs for such power levels. Attention is given to the design and control system approaches employed in these inverter designs to improve efficiency and reduce weight, along with the impact of such improved parameters on electric propulsion systems.

  2. Sub-millimeter resolution electrical conductivity images of brain tissues using magnetic resonance-based electrical impedance tomography

    NASA Astrophysics Data System (ADS)

    Oh, Tong In; Kim, Hyun Bum; Jeong, Woo Chul; Sajib, Saurav Z. K.; Kyung, Eun Jung; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

    2015-07-01

    Recent magnetic resonance (MR)-based electrical impedance tomography (MREIT) of in vivo animal and human subjects enabled the imaging of electromagnetic properties, such as conductivity and permittivity, on tissue structure and function with a few millimeter pixel size. At those resolutions, the conductivity contrast might be sufficient to distinguish different tissue type for certain applications. Since the precise measurement of electrical conductivity under the tissue levels can provide alternative information in a wide range of biomedical applications, it is necessary to develop high-resolution MREIT technique to enhance its availability. In this study, we provide the experimental evaluation of sub-millimeter resolution conductivity imaging method using a 3T MR scanner combined with a multi-echo MR pulse sequence, multi-channel RF coil, and phase optimization method. From the phantom and animal imaging results, sub-millimeter resolution exhibited similar signal-to-noise ratio of MR magnitude and noise levels in magnetic flux density comparing to the existing millimeter resolution. The reconstructed conductivity images at sub-millimeter resolution can distinguish different brain tissues with a pixel size as small as 350 μm.

  3. Sub-millimeter resolution electrical conductivity images of brain tissues using magnetic resonance-based electrical impedance tomography

    SciTech Connect

    Oh, Tong In; Jeong, Woo Chul; Sajib, Saurav Z. K.; Kim, Hyung Joong Woo, Eung Je; Kim, Hyun Bum; Kyung, Eun Jung; Kwon, Oh In

    2015-07-13

    Recent magnetic resonance (MR)-based electrical impedance tomography (MREIT) of in vivo animal and human subjects enabled the imaging of electromagnetic properties, such as conductivity and permittivity, on tissue structure and function with a few millimeter pixel size. At those resolutions, the conductivity contrast might be sufficient to distinguish different tissue type for certain applications. Since the precise measurement of electrical conductivity under the tissue levels can provide alternative information in a wide range of biomedical applications, it is necessary to develop high-resolution MREIT technique to enhance its availability. In this study, we provide the experimental evaluation of sub-millimeter resolution conductivity imaging method using a 3T MR scanner combined with a multi-echo MR pulse sequence, multi-channel RF coil, and phase optimization method. From the phantom and animal imaging results, sub-millimeter resolution exhibited similar signal-to-noise ratio of MR magnitude and noise levels in magnetic flux density comparing to the existing millimeter resolution. The reconstructed conductivity images at sub-millimeter resolution can distinguish different brain tissues with a pixel size as small as 350 μm.

  4. Magnetic resonance electrical impedance tomography (MREIT): conductivity and current density imaging

    NASA Astrophysics Data System (ADS)

    Seo, Jin Keun; Kwon, Ohin; Woo, Eung Je

    2005-01-01

    This paper reviews the latest impedance imaging technique called Magnetic Resonance Electrical Impedance Tomography (MREIT) providing information on electrical conductivity and current density distributions inside an electrically conducting domain such as the human body. The motivation for this research is explained by discussing conductivity changes related with physiological and pathological events, electromagnetic source imaging and electromagnetic stimulations. We briefly summarize the related technique of Electrical Impedance Tomography (EIT) that deals with cross-sectional image reconstructions of conductivity distributions from boundary measurements of current-voltage data. Noting that EIT suffers from the ill-posed nature of the corresponding inverse problem, we introduce MREIT as a new conductivity imaging modality providing images with better spatial resolution and accuracy. MREIT utilizes internal information on the induced magnetic field in addition to the boundary current-voltage measurements to produce three-dimensional images of conductivity and current density distributions. Mathematical theory, algorithms, and experimental methods of current MREIT research are described. With numerous potential applications in mind, future research directions in MREIT are proposed.

  5. Jumping Mechanism for Asteroid Rover with the Use of Resonance and Electrical Stiffness Switching

    NASA Astrophysics Data System (ADS)

    Sugawara, Yoshiki; Mizuguchi, Kou; Kobayashi, Nobuyuki

    It is not easy for asteroid rover with wheels to move on the surface of asteroids because such an astral body has two special features. One feature is that there is no air and it induces vacuum metalizing of metal slide components. The other feature is that their quite small gravity induces bad controllability of rover with wheels which requires enough frictional force between ground and wheels. Therefore, it is preferable for rover to use jumping mechanism without metal slide component and with low energy consumption. In this paper, a jumping mechanism is proposed and the mechanism uses a energy which is stored by resonance of flexible part. However, simply giving resonance results in low height of jumping. Therefore, electrical stiffness switching system is implemented to realize a effective jumping. Electrical stiffness switching is realized by piezoelectric element and external capacitor which is connected to them. Two method of stiffness switching are introduced. One is stiffness hardening and the other is stiffness softening which solve the problem of stiffness hardening. To validate the proposed mechanisms, numerical analyses are carried out and feasibilities of application for asteroid rover are studied.

  6. Transient electrically detected magnetic resonance spectroscopy applied to organic solar cells

    SciTech Connect

    Kraffert, Felix; Steyrleuthner, Robert; Meier, Christoph; Bittl, Robert; Behrends, Jan

    2015-07-27

    The influence of light-induced paramagnetic states on the photocurrent generated by polymer:fullerene solar cells is studied using spin-sensitive techniques in combination with laser-flash excitation. For this purpose, we developed a setup that allows for simultaneous detection of transient electron paramagnetic resonance as well as transient electrically detected magnetic resonance (trEDMR) signals from fully processed and encapsulated solar cells. Combining both techniques provides a direct link between photoinduced triplet excitons, charge transfer states, and free charge carriers as well as their influence on the photocurrent generated by organic photovoltaic devices. Our results obtained from solar cells based on poly(3-hexylthiophene) as electron donor and a fullerene-based electron acceptor show that the resonant signals observed in low-temperature (T = 80 K) trEDMR spectra can be attributed to positive polarons in the polymer as well as negative polarons in the fullerene phase, indicating that both centers are involved in spin-dependent processes that directly influence the photocurrent.

  7. Defect chemistry and electronic transport in low-κ dielectrics studied with electrically detected magnetic resonance

    NASA Astrophysics Data System (ADS)

    Mutch, Michael J.; Lenahan, Patrick M.; King, Sean W.

    2016-03-01

    Defect mediated electronic transport phenomena in low-κ dielectric films are of great technological interest for state-of-the-art and next generation microprocessors. At the present time, the leading low-κ interlayer dielectrics and etch-stop layers are based upon a-SiOC:H and a-SiCN:H, respectively. In this study, we utilize electrically detected magnetic resonance (EDMR), a derivative of electron paramagnetic resonance, to provide physical insight into electronic transport, as well as the nature and origin of defects in dense and porous a-SiOC:H and dense a-SiCN:H films. Resonance measurements are performed before and after the removal of sacrificial porogens via UV treatments to understand the role of specific defect centers in electronic transport in a-SiOC:H systems, and the nature of defects created by UV treatments. Unfortunately, a-SiOC:H and a-SiCN:H EDMR spectra are relatively broad and featureless. These featureless spectra are consistent with fairly complex a-SiOC:H and a-SiCN:H systems. We argue that physical insight may be gleaned from featureless spectra via multiple frequency EDMR. Baseline multiple frequency EDMR measurements are performed in a-Si:H and a-C:H to illustrate the nature of line broadening mechanisms of silicon and carbon related defects.

  8. All-electrical nonlinear fano resonance in coupled quantum point contacts

    NASA Astrophysics Data System (ADS)

    Xiao, Shiran

    This thesis is motivated by recent interest in the Fano resonance (FR). As a wave-interference phenomenon, this resonance is of increasing importance in optics, plasmon-ics, and metamaterials, where its ability to cause rapid signal modulations under variation of some suitable parameter makes it desirable for a variety of applications. In this thesis, I focus on a novel manifestation of this resonance in systems of coupled quantum point contacts (QPCs). The major finding of this work is that the FR in this system may be ma-nipulated by applying a nonlinear DC bias to the system. Under such conditions, we are able to induce significant distortions of resonance lineshape, providing a pathway to all-electrical manipulation of the FR. To interpret this behavior we apply a recently-developed model for a three-path FR, involving an additional "intruder" continuum. We have previously used this model to account for the magnetic-field induced distortions of the FR observed in coupled QPCs, and show here that this model also provides a frame-work for understanding the observed nonlinear behavior. Our work therefore reveals a new manifestation of the FR that can be sensitively tailored by external control, a finding that may eventually allow the application of this feature to nanoelectronics. Since the in-terference scheme involves in this thesis is a completely general one, it should be broadly applicable across a variety of different wave-based systems, including those in both pho-tonics and electronics and opening up the possibility of new applications in areas such as chemical and biological sensing and secure communications.

  9. Optically resonant magneto-electric cubic nanoantennas for ultra-directional light scattering

    SciTech Connect

    Sikdar, Debabrata Premaratne, Malin; Cheng, Wenlong

    2015-02-28

    Cubic dielectric nanoparticles are promising candidates for futuristic low-loss, ultra-compact, nanophotonic applications owing to their larger optical coefficients, greater packing density, and relative ease of fabrication as compared to spherical nanoparticles; besides possessing negligible heating at nanoscale in contrast to their metallic counterparts. Here, we present the first theoretical demonstration of azimuthally symmetric, ultra-directional Kerker's-type scattering of simple dielectric nanocubes in visible and near-infrared regions via simultaneous excitation and interference of optically induced electric- and magnetic-resonances up to quadrupolar modes. Unidirectional forward-scattering by individual nanocubes is observed at the first generalized-Kerker's condition for backward-scattering suppression, having equal electric- and magnetic-dipolar responses. Both directionality and magnitude of these unidirectional-scattering patterns get enhanced where matching electric- and magnetic-quadrupolar responses spectrally overlap. While preserving azimuthal-symmetry and backscattering suppression, a nanocube homodimer provides further directionality improvement for increasing interparticle gap, but with reduced main-lobe magnitude due to emergence of side-scattering lobes from diffraction-grating effect. We thoroughly investigate the influence of interparticle gap on scattering patterns and propose optimal range of gap for minimizing side-scattering lobes. Besides suppressing undesired side-lobes, significant enhancement in scattering magnitude and directionality is attained with increasing number of nanocubes forming a linear chain. Optimal directionality, i.e., the narrowest main-scattering lobe, is found at the wavelength of interfering quadrupolar resonances; whereas the largest main-lobe magnitude is observed at the wavelength satisfying the first Kerker's condition. These unique optical properties of dielectric nanocubes thus can revolutionize their

  10. Optically resonant magneto-electric cubic nanoantennas for ultra-directional light scattering

    NASA Astrophysics Data System (ADS)

    Sikdar, Debabrata; Cheng, Wenlong; Premaratne, Malin

    2015-02-01

    Cubic dielectric nanoparticles are promising candidates for futuristic low-loss, ultra-compact, nanophotonic applications owing to their larger optical coefficients, greater packing density, and relative ease of fabrication as compared to spherical nanoparticles; besides possessing negligible heating at nanoscale in contrast to their metallic counterparts. Here, we present the first theoretical demonstration of azimuthally symmetric, ultra-directional Kerker's-type scattering of simple dielectric nanocubes in visible and near-infrared regions via simultaneous excitation and interference of optically induced electric- and magnetic-resonances up to quadrupolar modes. Unidirectional forward-scattering by individual nanocubes is observed at the first generalized-Kerker's condition for backward-scattering suppression, having equal electric- and magnetic-dipolar responses. Both directionality and magnitude of these unidirectional-scattering patterns get enhanced where matching electric- and magnetic-quadrupolar responses spectrally overlap. While preserving azimuthal-symmetry and backscattering suppression, a nanocube homodimer provides further directionality improvement for increasing interparticle gap, but with reduced main-lobe magnitude due to emergence of side-scattering lobes from diffraction-grating effect. We thoroughly investigate the influence of interparticle gap on scattering patterns and propose optimal range of gap for minimizing side-scattering lobes. Besides suppressing undesired side-lobes, significant enhancement in scattering magnitude and directionality is attained with increasing number of nanocubes forming a linear chain. Optimal directionality, i.e., the narrowest main-scattering lobe, is found at the wavelength of interfering quadrupolar resonances; whereas the largest main-lobe magnitude is observed at the wavelength satisfying the first Kerker's condition. These unique optical properties of dielectric nanocubes thus can revolutionize their

  11. Electrical details of the ICRH resonant double loop matching sections of ITER

    NASA Astrophysics Data System (ADS)

    Durodié, F.; Bosia, G.; Lamalle, Ph.

    1997-04-01

    The use of short sections with very low characteristic impedance between the radiating part and the (matching) end-sections with sliding shorts of the International Thermonuclear Experimental Reactor (ITER) Resonant Double Loop (RDL) allows a design for this RDL which appears to be compatible with the expected mechanical loads during disruptions. In order to minimize the electric fields in these low impedance sections (which are at the high voltage parts of the RDL) a rounded rectangular cross-section can be used. It can further be dimensioned such as to modulate the parallel and perpendicular electric field components to common experience operating values: i.e. E⊥˜2×E∥ and E∥ less than 20 kV/cm. The paper reports expected electric fields and voltages in these low impedance sections. Corrections due to 3D-effects on the dimensions of all the sections as well as their influence on the current distribution in the sliding shorts in operating conditions when the shorts are nearest to such low impedance sections are shown to be negligible.

  12. The calculation of electrical parameters of AT-cut quartz crystal resonators with the consideration of material viscosity.

    PubMed

    Wang, Ji; Zhao, Wenhua; Du, Jianke; Hu, Yuantai

    2011-01-01

    Electrical parameters like resistance and quality factor of a quartz crystal resonator cannot be determined through vibration analysis without considering the presence of material dissipation. In this study, we use the first-order Mindlin plate equations of piezoelectric plates for thickness-shear vibrations of a simple resonator model with partial electrodes. We derive the expressions of electrical parameters with emphasis on the resistance that is related to the imaginary part of complex elastic constants, or the viscosity, of quartz crystal. Since all electrical parameters are frequency dependent, this procedure provides the chance to study the frequency behavior of crystal resonators with a direct formulation. We understand that the electrical parameters are strongly affected by the manufacturing process, with the plating techniques in particular, but the theoretical approach we presented here will be the first step for the precise estimation of such parameters and their further applications in the analysis of nonlinear behavior of resonators. We calculated the parameters from our simple resonator model of AT-cut quartz crystal with the first-order Mindlin plate theory to demonstrate the procedure and show that the numerical results are consistent with earlier measurements. PMID:20594568

  13. High-frequency performance of electric field sensors aboard the RESONANCE satellite

    NASA Astrophysics Data System (ADS)

    Sampl, M.; Macher, W.; Gruber, C.; Oswald, T.; Kapper, M.; Rucker, H. O.; Mogilevsky, M.

    2015-05-01

    We present the high-frequency properties of the eight electric field sensors as proposed to be launched on the spacecraft "RESONANCE" in the near future. Due to the close proximity of the conducting spacecraft body, the sensors (antennas) have complex receiving features and need to be well understood for an optimal mission and spacecraft design. An optimal configuration and precise understanding of the sensor and antenna characteristics is also vital for the proper performance of spaceborne scientific instrumentation and the corresponding data analysis. The provided results are particularly interesting with regard to the planned mutual impedance experiment for measuring plasma parameters. Our computational results describe the extreme dependency of the sensor system with regard to wave incident direction and frequency, and provides the full description of the sensor system as a multi-port scatterer. In particular, goniopolarimetry techniques like polarization analysis and direction finding depend crucially on the presented antenna characteristics.

  14. Measurement of electrical current density distribution in a simple head phantom with magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Gamba, Humberto R.; Bayford, Richard; Holder, David

    1999-01-01

    Knowledge of the influence of the human skull on the electrical current (d.c.) distribution within the brain tissue could prove useful in measuring impedance changes inside the human head. These changes can be related to physiological functions. The studies presented in this paper examine the current density distribution in a simple phantom consisting of a saline filled tank (to simulate scalp and brain) and a ring made of dental grade plaster of Paris (to simulate the human skull). Images of the distribution of the d.c. density of the phantom with and without the plaster of Paris ring were produced using a magnetic resonance imaging technique. These images indicate that the skull is likely to produce a more uniform d.c. density within the brain.

  15. Change of electrical conductivity of Ar welding arc under resonant absorption of laser radiation

    NASA Astrophysics Data System (ADS)

    Kozakov, R.; Emde, B.; Pipa, A. V.; Huse, M.; Uhrlandt, D.; Hermsdorf, J.; Wesling, V.

    2015-03-01

    Experimental investigations of the impact of resonant laser absorption by a tungsten inert gas welding arc in argon are presented. The intensity increase of the arc’s radiation between the laser entrance height and the anode are observed, as well as the variation of arc voltage due to the presence of the laser beam. High-speed camera recordings from different directions combined with absolutely calibrated spectroscopic measurements allow the reconstruction of the three-dimensional emission coefficient profiles without the assumption of axial symmetry. The obtained data are evaluated within the framework of local thermodynamic equilibrium. The local increase in the temperature and conductivity due to the influence of the laser is determined. Changes in the electrical conductivity obtained from the optical measurements coincide well with the measured voltage drop, and show significant redistribution of the current density profile near the anode in particular.

  16. Electrical activation and electron spin resonance measurements of arsenic implanted in silicon

    SciTech Connect

    Hori, Masahiro; Ono, Yukinori; Uematsu, Masashi; Fujiwara, Akira

    2015-04-06

    The electrical activation of arsenic (As) implanted in Si is investigated with electron spin resonance (ESR), spreading resistance (SR), and secondary ion mass spectroscopy (SIMS). The As ions were implanted with a dose of 1 × 10{sup 12 }cm{sup −2} and subsequently annealed at various temperatures in the range of 500–1100 °C. The ESR measurements at 10 K show that the density of the As donor electrons for all the annealing temperatures is less than 10% of the As atom concentration measured by SIMS. The SR data indicate that the density of conduction band electrons is several times larger than that of the As donor electrons. These results strongly suggest that most of the As donor electrons are ESR inactive at low temperatures.

  17. Coherent control of magnetization precession in electrically detected time domain ferromagnetic resonance

    SciTech Connect

    Wid, O.; Wahler, M.; Homonnay, N.; Richter, T.; Schmidt, G.

    2015-11-15

    We demonstrate coherent control of time domain ferromagnetic resonance by all electrical excitation and detection. Using two ultrashort magnetic field steps with variable time delay we control the induction decay in yttrium iron garnet (YIG). By setting suitable delay times between the two steps the precession of the magnetization can either be enhanced or completely stopped. The method allows for a determination of the precession frequency within a few precession periods and with an accuracy much higher than can be achieved using fast fourier transformation. Moreover it holds the promise to massively increase precession amplitudes in pulsed inductive microwave magnetometry (PIMM) using low amplitude finite pulse trains. Our experiments are supported by micromagnetic simulations which nicely confirm the experimental results.

  18. Resonant snubber based soft-switching inverters for electric propulsion drives

    SciTech Connect

    Lai, J.S.

    1996-05-01

    This paper summarizes recently developed soft-switching inverters and proposes two alternative options for electric propulsion drives. The newly developed soft-switching inverter employs an auxiliary switch and a resonant inductor per phase to produce a zero voltage across the main switch so that the main switch can turn on at the zero-voltage condition. Both the auxiliary switch and the resonant inductor are operating at a fractional duty, and thus are small in size as compared to the main inverter circuit components. Operation modes in a complete zero-voltage switching cycle for the single-phase soft-switching inverter are described in detail with graphical explanations. The circuit operation was first verified by a computer simulation and then tested with an 1-kW single-phase and an 100-kW three-phase inverters. Experimental results are presented to show the superior performance in efficiency improvement, EMI reduction, and dv/dt reduction of the proposed soft-switching inverters.

  19. Miniaturized sharp band-pass filter based on complementary electric-LC resonator

    NASA Astrophysics Data System (ADS)

    Torabi, Yalda; Dadashzadeh, Golamreza; Oraizi, Homayoon

    2016-04-01

    In this paper, a novel application of complementary electric-LC (CELC) resonator as a basic element to synthesize miniaturized sharp band-pass filters is introduced. The proposed metamaterial band-pass filter is a three-stage CELC-based device, where two shunt short-circuited stubs are employed in the input and output stages and a series gap is etched in the middle stage. By these means, a high-selectivity prototype band-pass filter with 2 % fractional bandwidth in S band is designed and fabricated. The out-of-band attenuation is better than 40 dB, and the upper and lower transition bands are also quite sharp due to the presence of two transmission zeros (nearly 60 and 30 dB fall in 0.2 GHz at lower and upper edges, respectively). Moreover, the filter is substantially miniaturized with a size of effective region of 1.3 cm × 1 cm at 2.9 GHz, which is quite smaller relative to conventional designs with the same performance. The fabrication and measurement of the proposed filter configuration attest to its expected desirable features. Therefore, the application of CELC resonator is proposed for super-compact sharp band-pass filters.

  20. A new resonance-frequency based electrical impedance spectroscopy and its application in biomedical engineering

    NASA Astrophysics Data System (ADS)

    Dhurjaty, Sreeram; Qiu, Yuchen; Tan, Maxine; Zheng, Bin

    2014-03-01

    Electrical Impedance Spectroscopy (EIS) has shown promising results for differentiating between malignant and benign tumors, which exhibit different dielectric properties. However, the performance of current EIS systems has been inadequate and unacceptable in clinical practice. In the last several years, we have been developing and testing a new EIS approach using resonance frequencies for detection and classification of suspicious tumors. From this experience, we identified several limitations of current technologies and designed a new EIS system with a number of new characteristics that include (1) an increased A/D (analog-to-digital) sampling frequency, 24 bits, and a frequency resolution of 100 Hz, to increase detection sensitivity (2) automated calibration to monitor and correct variations in electronic components within the system, (3) temperature sensing and compensation algorithms to minimize impact of environmental change during testing, and (4) multiple inductor-switching to select optimum resonance frequencies. We performed a theoretical simulation to analyze the impact of adding these new functions for improving performance of the system. This system was also tested using phantoms filled with variety of liquids. The theoretical and experimental test results are consistent with each other. The experimental results demonstrated that this new EIS device possesses the improved sensitivity and/or signal detection resolution for detecting small impedance or capacitance variations. This provides the potential of applying this new EIS technology to different cancer detection and diagnosis tasks in the future.

  1. Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

    NASA Astrophysics Data System (ADS)

    Cho, Herman

    2016-09-01

    Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3 / 2 , 5 / 2 , 7 / 2, and 9 / 2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Applications of NQR methods to studies of electronic structure in heavy element systems are proposed.

  2. Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

    DOE PAGESBeta

    Cho, Herman

    2016-02-28

    Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3/2,5/2,7/2, and 9/2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Furthermore, applications of NQR methods to studies of electronic structure in heavy element systems are proposed.

  3. DNA-Assembled Nanoparticle Rings Exhibit Electric and Magnetic Resonances at Visible Frequencies

    PubMed Central

    2015-01-01

    Metallic nanostructures can be used to manipulate light on the subwavelength scale to create tailored optical material properties. Next to electric responses, artificial optical magnetism is of particular interest but difficult to achieve at visible wavelengths. DNA-self-assembly has proved to serve as a viable method to template plasmonic materials with nanometer precision and to produce large quantities of metallic objects with high yields. We present here the fabrication of self-assembled ring-shaped plasmonic metamolecules that are composed of four to eight single metal nanoparticles with full stoichiometric and geometric control. Scattering spectra of single rings as well as absorption spectra of solutions containing the metamolecules are used to examine the unique plasmonic features, which are compared to computational simulations. We demonstrate that the electric and magnetic plasmon resonance modes strongly correlate with the exact shape of the structures. In particular, our computations reveal the magnetic plasmons only for particle rings of broken symmetries, which is consistent with our experimental data. We stress the feasibility of DNA self-assembly as a method to create bulk plasmonic materials and metamolecules that may be applied as building blocks in plasmonic devices. PMID:25611357

  4. DNA-assembled nanoparticle rings exhibit electric and magnetic resonances at visible frequencies.

    PubMed

    Roller, Eva-Maria; Khorashad, Larousse Khosravi; Fedoruk, Michael; Schreiber, Robert; Govorov, Alexander O; Liedl, Tim

    2015-02-11

    Metallic nanostructures can be used to manipulate light on the subwavelength scale to create tailored optical material properties. Next to electric responses, artificial optical magnetism is of particular interest but difficult to achieve at visible wavelengths. DNA-self-assembly has proved to serve as a viable method to template plasmonic materials with nanometer precision and to produce large quantities of metallic objects with high yields. We present here the fabrication of self-assembled ring-shaped plasmonic metamolecules that are composed of four to eight single metal nanoparticles with full stoichiometric and geometric control. Scattering spectra of single rings as well as absorption spectra of solutions containing the metamolecules are used to examine the unique plasmonic features, which are compared to computational simulations. We demonstrate that the electric and magnetic plasmon resonance modes strongly correlate with the exact shape of the structures. In particular, our computations reveal the magnetic plasmons only for particle rings of broken symmetries, which is consistent with our experimental data. We stress the feasibility of DNA self-assembly as a method to create bulk plasmonic materials and metamolecules that may be applied as building blocks in plasmonic devices. PMID:25611357

  5. Tissue electrical property mapping from zero echo-time magnetic resonance imaging.

    PubMed

    Lee, Seung-Kyun; Bulumulla, Selaka; Wiesinger, Florian; Sacolick, Laura; Sun, Wei; Hancu, Ileana

    2015-02-01

    The capability of magnetic resonance imaging (MRI) to produce spatially resolved estimation of tissue electrical properties (EPs) in vivo has been a subject of much recent interest. In this work we introduce a method to map tissue EPs from low-flip-angle, zero-echo-time (ZTE) imaging. It is based on a new theoretical formalism that allows calculation of EPs from the product of transmit and receive radio-frequency (RF) field maps. Compared to conventional methods requiring separation of the transmit RF field (B(1)(+)) from acquired MR images, the proposed method has such advantages as: 1) reduced theoretical error, 2) higher acquisition speed, and 3) flexibility in choice of different transmit and receive RF coils. The method is demonstrated in electrical conductivity and relative permittivity mapping in a salt water phantom, as well as in vivo measurement of brain conductivity in healthy volunteers. The phantom results show the validity and scan-time efficiency of the proposed method applied to a piece-wise homogeneous object. Quality of in vivo EP results was limited by reconstruction errors near tissue boundaries, which highlights need for image segmentation in EP mapping in a heterogeneous medium. Our results show the feasibility of rapid EP mapping from MRI without B(1)(+) mapping. PMID:25312919

  6. Tailoring the multiple electrically resonant transparency through bi-layered metamaterial-induced coupling oscillators

    NASA Astrophysics Data System (ADS)

    Zhao, Jiaxin; Han, Song; Lin, Hai; Yang, Helin

    2015-11-01

    Metamaterials (MMs) can be tailored to support electromagnetic interference, which is the kernel for the material-based electromagnetically induced transparency (EIT) phenomena, alternatively transparency based on electric interference can be deemed as electrically resonant transparency (ERT). Here, we experimentally and theoretically demonstrate two kinds of bi-layered MMs. The C3-C6 hybrid MM exhibits triple-mode ERT with transmission peaks of 0.84 at 9.6 GHz, 0.92 at 10.4 GHz, and 0.93 at 11.5 GHz for the horizontally polarized wave, and dual-mode ERT with transmission peaks of 0.84 at 8.8 GHz and 0.91 at 10.2 GHz for the vertically polarized wave. However, the C4-C8 hybrid MM, with two stable transparent peaks of 0.92 and 0.88 at 10.46 GHz and 11.61 GHz, is proven to be polarization independent. The measured results show excellent agreement with numerical simulations. A coupled oscillator model is employed to theoretically study the near field interference between the induced dipoles on the transmission properties. The results presented here will find their application value for multi-mode slow light devices, filters and attenuators, and so on.

  7. Electric dipole spin resonance in systems with a valley-dependent g factor

    NASA Astrophysics Data System (ADS)

    Rančić, Marko J.; Burkard, Guido

    2016-05-01

    In this theoretical study we qualitatively and quantitatively investigate the electric dipole spin resonance (EDSR) in a single Si/SiGe quantum dot in the presence of a magnetic field gradient, e.g., produced by a ferromagnet. We model a situation in which the control of electron spin states is achieved by applying an oscillatory electric field, inducing real-space oscillations of the electron inside the quantum dot. One of the goals of our study is to present a microscopic theory of valley-dependent g factors in Si/SiGe quantum dots and investigate how valley relaxation combined with a valley-dependent g factor leads to a novel electron spin dephasing mechanism. Furthermore, we discuss the interplay of spin and valley relaxations in Si/SiGe quantum dots. Our findings suggest that the electron spin dephases due to valley relaxation, and are in agreement with recent experimental studies [Nat. Nanotechnol. 9, 666 (2014), 10.1038/nnano.2014.153].

  8. Tuning Localized Transverse Surface Plasmon Resonance in Electricity-Selected Single-Wall Carbon Nanotubes by Electrochemical Doping

    NASA Astrophysics Data System (ADS)

    Igarashi, Toru; Kawai, Hideki; Yanagi, Kazuhiro; Cuong, Nguyen Thanh; Okada, Susumu; Pichler, Thomas

    2015-05-01

    Localized surface-plasmon resonance affects the optical absorption and scattering of nanosized materials. The intensities and peak energies of the surface plasmons strongly depend on the carrier density; thus, the optical absorption peaks originating from the surface-plasmon resonance can be manipulated by the density of injected carriers. In single-wall carbon nanotubes (SWCNTs), the correct identification of surface-plasmon resonance modes is of great interest due to their emerging plasmonic and optoelectronic applications. Here, we demonstrate that high-carrier injection by electric double layers can induce a transverse surface-plasmon peak in aggregated, electricity-selected SWCNTs. In contrast to the well-discussed surface-plasmon resonance mode, whose polarization is parallel to the axis and whose resonance frequency is located in the THz region, our identified mode, which was normal to the axis, was located in the near-infrared range. In addition, our mode's peak position and intensities were tunable by carrier injections, indicating a route to control plasmonic optical processes by electric double-layer carrier injections using ionic liquid.

  9. Conductance and resonant tunneling in multi-channel double barrier structures under transverse and longitudinal electric fields

    SciTech Connect

    Pereyra, Pedro Mendoza-Figueroa, M. G.

    2015-03-21

    Transport properties of electrons through biased double barrier semiconductor structures with finite transverse width w{sub y}, in the presence of a channel-mixing transverse electric field E{sub T} (along the y-axis), were studied. We solve the multichannel Schrödinger equation using the transfer matrix method and transport properties, like the conductance G and the transmission coefficients T{sub ij} have been evaluated as functions of the electrons' energy E and the transverse and longitudinal (bias) electric forces, f{sub T} and f{sub b}. We show that peak-suppression effects appear, due to the applied bias. Similarly, coherent interference of wave-guide states induced by the transverse field is obtained. We show also that the coherent interference of resonant wave-guide states gives rise to resonant conductance, which can be tuned to produce broad resonant peaks, implying operation frequencies of the order of 10 THz or larger.

  10. Theory and experimental verifications of the resonator Q and equivalent electrical parameters due to viscoelastic and mounting supports losses.

    PubMed

    Yong, Yook-Kong; Patel, Mihir S; Tanaka, Masako

    2010-08-01

    A novel analytical/numerical method for calculating the resonator Q and its equivalent electrical parameters due to viscoelastic, conductivity, and mounting supports losses is presented. The method presented will be quite useful for designing new resonators and reducing the time and costs of prototyping. There was also a necessity for better and more realistic modeling of the resonators because of miniaturization and the rapid advances in the frequency ranges of telecommunication. We present new 3-D finite elements models of quartz resonators with viscoelasticity, conductivity, and mounting support losses. The losses at the mounting supports were modeled by perfectly matched layers (PMLs). A previously published theory for dissipative anisotropic piezoelectric solids was formulated in a weak form for finite element (FE) applications. PMLs were placed at the base of the mounting supports to simulate the energy losses to a semi-infinite base substrate. FE simulations were carried out for free vibrations and forced vibrations of quartz tuning fork and AT-cut resonators. Results for quartz tuning fork and thickness shear AT-cut resonators were presented and compared with experimental data. Results for the resonator Q and the equivalent electrical parameters were compared with their measured values. Good equivalences were found. Results for both low- and high-Q AT-cut quartz resonators compared well with their experimental values. A method for estimating the Q directly from the frequency spectrum obtained for free vibrations was also presented. An important determinant of the quality factor Q of a quartz resonator is the loss of energy from the electrode area to the base via the mountings. The acoustical characteristics of the plate resonator are changed when the plate is mounted onto a base substrate. The base affects the frequency spectra of the plate resonator. A resonator with a high Q may not have a similarly high Q when mounted on a base. Hence, the base is an

  11. Generation of terahertz radiation in the interaction of coherent electromagnetic wave with a resonant medium in a constant external electric field

    NASA Astrophysics Data System (ADS)

    Basharov, A. M.

    2016-05-01

    The paper shows that it is sufficient to place a resonance medium in an external dc electric field for the generation of low-frequency radiation at the resonant interaction of the medium and a coherent wave with carrier frequency of the optical range. Under certain conditions the carrier frequency of the generated radiation equals the Rabi frequency of the resonant interaction.

  12. Electric-field-induced spin resonance in antiferromagnetic insulators: Inverse process of the dynamical chiral magnetic effect

    NASA Astrophysics Data System (ADS)

    Sekine, Akihiko; Chiba, Takahiro

    2016-06-01

    We propose a realization of the electric-field-induced antiferromagnetic resonance. We consider three-dimensional antiferromagnetic insulators with spin-orbit coupling characterized by the existence of a topological term called the θ term. By solving the Landau-Lifshitz-Gilbert equation in the presence of the θ term, we show that, in contrast to conventional methods using ac magnetic fields, the antiferromagnetic resonance state is realized by ac electric fields along with static magnetic fields. This mechanism can be understood as the inverse process of the dynamical chiral magnetic effect, an alternating current generation by magnetic fields. In other words, we propose a way to electrically induce the dynamical axion field in condensed matter. We discuss a possible experiment to observe our proposal, which utilizes the spin pumping from the antiferromagnetic insulator into a heavy metal contact.

  13. Classification of thyroid nodules using a resonance-frequency-based electrical impedance spectroscopy: progress assessment

    NASA Astrophysics Data System (ADS)

    Zheng, Bin; Tublin, Mitchell E.; Lederman, Dror; Klym, Amy H.; Brown, Erica D.; Gur, David

    2012-02-01

    The incidence of thyroid cancer is rising faster than other malignancies and has nearly doubled in the United States (U.S.) in the last 30 years. However, classifying between malignant and benign thyroid nodules is often difficult. Although ultrasound guided Fine Needle Aspiration Biopsy (FNAB) is considered an excellent tool for triaging patients, up to 25% of FNABs are inconclusive. As a result, definitive diagnosis requires an exploratory surgery and a large number of these are performed in the U.S. annually. It would be extremely beneficial to develop a non-invasive tool or procedure that could assist in assessing the likelihood of malignancy of otherwise indeterminate thyroid nodules, thereby reducing the number of exploratory thyroidectomies that are performed under general anesthesia. In this preliminary study we demonstrate a unique hand-held Resonance-frequency based Electrical Impedance Spectroscopy (REIS) device with six pairs of detection probes to detect and classify thyroid nodules using multi-channel EIS output signal sweeps. Under an Institutional Review Board (IRB)-approved case collection protocol, this REIS device is being tested in our clinical facility and we have been collecting an initial patient data set since March of this year. Between March and August of 2011, 65 EIS tests were conducted on 65 patients. Among these cases, six depicted pathology-verified malignant cells. Our initial assessment indicates the feasibility of easily applying this REIS device and measurement approach in a very busy clinical setting. The measured resonance frequency differences between malignant and benign nodules could potentially make it possible to accurately classify indeterminate thyroid nodules.

  14. Resonance

    NASA Astrophysics Data System (ADS)

    Perozzi, E.; Murdin, P.

    2000-11-01

    A resonance in CELESTIAL MECHANICS occurs when some of the quantities characterizing the motion of two or more celestial bodies can be considered as commensurable, i.e. their ratio is close to an integer fraction. In a simplified form, this can be expressed as ...

  15. Assessing risk of thyroid cancer using resonance-frequency based electrical impedance measurements

    NASA Astrophysics Data System (ADS)

    Zheng, Bin; Tublin, Mitchell E.; Lederman, Dror; Klym, Amy H.; Brown, Erica D.; Gur, David

    2011-03-01

    The incidence of thyroid cancer has risen faster than many malignancies and has nearly doubled in the USA over the past 30 years. Palpable nodules and subclinical nodules detected by imaging are found in a large percentage of the USA population. Most of these (.>95%) are fortunately benign. This vast reservoir of nodules makes the detection and diagnosis of thyroid cancer a diagnostic dilemma. Ultrasound guided Fine Needle Aspiration Biopsy (FNAB) is excellent for triaging patients but up to 25% of FNABs are inconclusive. As a result, definitive diagnosis is often only possible with a diagnostic lobectomy; many thousands of these are performed in the USA annually for ultimately benign disease. It would be extremely beneficial if we could develop a non-invasive procedure that could assist the diagnostician in reliably predicting the likelihood of malignancy of otherwise indeterminate thyroid nodules, thereby reducing the number of these "exploratory/diagnostic" lobectomies performed under general anesthesia. Electrical Impedance Spectroscopy (EIS) was considered as a possible approach to address this problem. However, the diagnostic accuracy of EIS is too low for routine clinical use to date. In our group, we developed a substantially modified technology termed Resonance-frequency Electrical Impedance Spectroscopy (REIS), which yields usable information for classifying risk of having breast abnormalities. We preliminarily applied REIS to measure signals on participants having thyroid nodules aiming to assess whether we can assist in improving diagnosis of indeterminate thyroid nodules. In this study we present a new multi-probe based REIS device specifically designed for the assessment of indeterminate thyroid nodules. Our preliminary assessment presented here demonstrates the feasibility of using this proposed REIS device in a busy tertiary care center.

  16. Design of electric-field assisted surface plasmon resonance system for the detection of heavy metal ions in water

    SciTech Connect

    Kyaw, Htet Htet; Boonruang, Sakoolkan E-mail: waleed.m@bu.ac.th; Mohammed, Waleed S. E-mail: waleed.m@bu.ac.th; Dutta, Joydeep

    2015-10-15

    Surface Plasmon Resonance (SPR) sensors are widely used in diverse applications. For detecting heavy metal ions in water, surface functionalization of the metal surface is typically used to adsorb target molecules, where the ionic concentration is detected via a resonance shift (resonance angle, resonance wavelength or intensity). This paper studies the potential of a possible alternative approach that could eliminate the need of using surface functionalization by the application of an external electric field in the flow channel. The exerted electrical force on the ions pushes them against the surface for enhanced adsorption; hence it is referred to as “Electric-Field assisted SPR system”. High system sensitivity is achieved by monitoring the time dynamics of the signal shift. The ion deposition dynamics are discussed using a derived theoretical model based on ion mobility in water. On the application of an appropriate force, the target ions stack onto the sensor surface depending on the ionic concentration of target solution, ion mass, and flow rate. In the experimental part, a broad detection range of target cadmium ions (Cd{sup 2+}) in water from several parts per million (ppm) down to a few parts per billion (ppb) can be detected.

  17. Design of electric-field assisted surface plasmon resonance system for the detection of heavy metal ions in water

    NASA Astrophysics Data System (ADS)

    Kyaw, Htet Htet; Boonruang, Sakoolkan; Mohammed, Waleed S.; Dutta, Joydeep

    2015-10-01

    Surface Plasmon Resonance (SPR) sensors are widely used in diverse applications. For detecting heavy metal ions in water, surface functionalization of the metal surface is typically used to adsorb target molecules, where the ionic concentration is detected via a resonance shift (resonance angle, resonance wavelength or intensity). This paper studies the potential of a possible alternative approach that could eliminate the need of using surface functionalization by the application of an external electric field in the flow channel. The exerted electrical force on the ions pushes them against the surface for enhanced adsorption; hence it is referred to as "Electric-Field assisted SPR system". High system sensitivity is achieved by monitoring the time dynamics of the signal shift. The ion deposition dynamics are discussed using a derived theoretical model based on ion mobility in water. On the application of an appropriate force, the target ions stack onto the sensor surface depending on the ionic concentration of target solution, ion mass, and flow rate. In the experimental part, a broad detection range of target cadmium ions (Cd2+) in water from several parts per million (ppm) down to a few parts per billion (ppb) can be detected.

  18. Fano-like resonance emerging from magnetic and electric plasmon mode coupling in small arrays of gold particles.

    PubMed

    Bakhti, Saïd; Tishchenko, Alexandre V; Zambrana-Puyalto, Xavier; Bonod, Nicolas; Dhuey, Scott D; Schuck, P James; Cabrini, Stefano; Alayoglu, Selim; Destouches, Nathalie

    2016-01-01

    In this work we theoretically and experimentally analyze the resonant behavior of individual 3 × 3 gold particle oligomers illuminated under normal and oblique incidence. While this structure hosts both dipolar and quadrupolar electric and magnetic delocalized modes, only dipolar electric and quadrupolar magnetic modes remain at normal incidence. These modes couple into a strongly asymmetric spectral response typical of a Fano-like resonance. In the basis of the coupled mode theory, an analytical representation of the optical extinction in terms of singular functions is used to identify the hybrid modes emerging from the electric and magnetic mode coupling and to interpret the asymmetric line profiles. Especially, we demonstrate that the characteristic Fano line shape results from the spectral interference of a broad hybrid mode with a sharp one. This structure presents a special feature in which the electric field intensity is confined on different lines of the oligomer depending on the illumination wavelength relative to the Fano dip. This Fano-type resonance is experimentally observed performing extinction cross section measurements on arrays of gold nano-disks. The vanishing of the Fano dip when increasing the incidence angle is also experimentally observed in accordance with numerical simulations. PMID:27580515

  19. Fano-like resonance emerging from magnetic and electric plasmon mode coupling in small arrays of gold particles

    PubMed Central

    Bakhti, Saïd; Tishchenko, Alexandre V.; Zambrana-Puyalto, Xavier; Bonod, Nicolas; Dhuey, Scott D.; Schuck, P. James; Cabrini, Stefano; Alayoglu, Selim; Destouches, Nathalie

    2016-01-01

    In this work we theoretically and experimentally analyze the resonant behavior of individual 3 × 3 gold particle oligomers illuminated under normal and oblique incidence. While this structure hosts both dipolar and quadrupolar electric and magnetic delocalized modes, only dipolar electric and quadrupolar magnetic modes remain at normal incidence. These modes couple into a strongly asymmetric spectral response typical of a Fano-like resonance. In the basis of the coupled mode theory, an analytical representation of the optical extinction in terms of singular functions is used to identify the hybrid modes emerging from the electric and magnetic mode coupling and to interpret the asymmetric line profiles. Especially, we demonstrate that the characteristic Fano line shape results from the spectral interference of a broad hybrid mode with a sharp one. This structure presents a special feature in which the electric field intensity is confined on different lines of the oligomer depending on the illumination wavelength relative to the Fano dip. This Fano-type resonance is experimentally observed performing extinction cross section measurements on arrays of gold nano-disks. The vanishing of the Fano dip when increasing the incidence angle is also experimentally observed in accordance with numerical simulations. PMID:27580515

  20. Design of Hybrid Electrochromic Materials with Large Electrical Modulation of Plasmonic Resonances.

    PubMed

    Ledin, Petr A; Jeon, Ju-Won; Geldmeier, Jeffrey A; Ponder, James F; Mahmoud, Mahmoud A; El-Sayed, Mostafa; Reynolds, John R; Tsukruk, Vladimir V

    2016-05-25

    We present a rational approach to fabricating plasmonically active hybrid polymer-metal nanomaterials with electrochemical tunability of the localized surface plasmon resonances (LSPRs) of noble metal nanostructures embedded in an electroactive polymer matrix. The key requirement for being able to significantly modulate the LSPR band position is a close overlap between the refractive index change [Δn(λ)] of a stimuli-responsive polymeric matrix and the intrinsic LSPR bands. For this purpose, gold nanorods with a controlled aspect ratio, synthesized to provide high refractive index sensitivity while maintaining good oxidative stability, were combined with a solution-processable electroactive and electrochromic polymer (ECP): alkoxy-substituted poly(3,4-propylenedioxythiophene) [PProDOT(CH2OEtHx)2]. Spectral characteristics of the ECP, in particular the Δn(λ) variation, were evaluated as the material was switched between oxidized and reduced states. We fabricated ultrathin plasmonic electrochromic hybrid films consisting of gold nanorods and ECP that exhibited a large, stable, and reversible LSPR modulation of up to 25-30 nm with an applied electrical potential. Finite-difference time-domain (FDTD) simulations confirm a good match between the experimentally measured refractive index change in the ECP and the plasmonic response during electrochemical modulations. PMID:27145297

  1. Magnetic resonance and electrical properties of p-toluene sulphonic acid doped polyaniline

    NASA Astrophysics Data System (ADS)

    Arora, Manju; Arya, S. K.; Barala, Sunil Kumar; Saini, Parveen

    2013-06-01

    p-Toluene Sulphonic Acid (PTSA) doped polyaniline (PANI) analogues were synthesized by oxidative chemical polymerization method and characterized by TGA FTIR and EPR spectroscopic techniques. FTIR spectra indicates the formation of PTSA doped PANI and also revealed the dopant ions mediated interactions between polymeric chain through weak hydrogen bonding. TGA plots revealed that there is systematic variation in the weight loss at ˜300 °C from ˜4% to ˜38% with increase in dopant concentration from 0.01 N to 1.0 N. Magnetic resonance spectra of polaron charge carriers exhibit the single Lorentzian line signal with the Dysonian contribution indicating formation of metal-like domains. The polarons are localized in these domains by strong interaction between the neighboring conducting chains, in which the charge is transferred by quasi-three-dimensional (Q3D) delocalized electron. In higher concentration analogue some of polarons merge into diamagnetic bipolarons and this reduces intensity of EPR signal. The electrical conductivity of the 1.0 N PTSA doped sample was ˜4.5 S/cm which satisfies the EMI shielding criteri.

  2. Investigation of the Influence of the Clearance of Linear Alternator on Thermo-acoustic Electricity Generator without Resonator

    NASA Astrophysics Data System (ADS)

    Wang, Yufang; Li, Zhengyu; Li, Qing

    This paper proposes a thermo-acoustic electricity generator without resonator, which is realized by a looped-tube traveling-wave thermo-acoustic engine coupled with two linear alternators. A linear alternator is the resonating element of the thermo-acoustic engine, so its impedance determines the operating status and the clearance exerts a direct influence on it. A test bed is set to measure the clearance. An exact formula is determined after the analysis of data processing. This conclusion is used in the simulation of the influence of clearance and damping based on DeltaEC. At last, a series of experiments have been done to compare with the simulation.

  3. Electric field signatures of the IAR and Schumann resonance in the upper ionosphere detected by Chibis-M microsatellite

    NASA Astrophysics Data System (ADS)

    Dudkin, D.; Pilipenko, V.; Korepanov, V.; Klimov, S.; Holzworth, R.

    2014-09-01

    We tried to find with the ULF/ELF electric field sensor onboard Chibis-M microsatellite signatures of the IAR (Ionospheric Alfvén Resonator) and Schumann resonance (SR) in the upper ionosphere. Whereas observations of the IAR and SR multi-band emissions with ground magnetometers are ubiquitous, in-situ satellite observations of their signatures are very rare. ULF events detected by the Chibis-M show a possibility of triggered excitation of IAR. In contrast to dominating view, IAR has been found to be effectively excited on the dayside, too. Chibis-M observations also supported the possibility of the SR leakage into the upper ionosphere.

  4. Assembling a prototype resonance electrical impedance spectroscopy system for breast tissue signal detection: preliminary assessment

    NASA Astrophysics Data System (ADS)

    Sumkin, Jules; Zheng, Bin; Gruss, Michelle; Drescher, John; Leader, Joseph; Good, Walter; Lu, Amy; Cohen, Cathy; Shah, Ratan; Zuley, Margarita; Gur, David

    2008-03-01

    Using electrical impedance spectroscopy (EIS) technology to detect breast abnormalities in general and cancer in particular has been attracting research interests for decades. Large clinical tests suggest that current EIS systems can achieve high specificity (>= 90%) at a relatively low sensitivity ranging from 15% to 35%. In this study, we explore a new resonance frequency based electrical impedance spectroscopy (REIS) technology to measure breast tissue EIS signals in vivo, which aims to be more sensitive to small tissue changes. Through collaboration between our imaging research group and a commercial company, a unique prototype REIS system has been assembled and preliminary signal acquisition has commenced. This REIS system has two detection probes mounted in the two ends of a Y-shape support device with probe separation of 60 mm. During REIS measurement, one probe touches the nipple and the other touches to an outer point of the breast. The electronic system continuously generates sweeps of multi-frequency electrical pulses ranging from 100 to 4100 kHz. The maximum electric voltage and the current applied to the probes are 1.5V and 30mA, respectively. Once a "record" command is entered, multi-frequency sweeps are recorded every 12 seconds until the program receives a "stop recording" command. In our imaging center, we have collected REIS measurements from 150 women under an IRB approved protocol. The database includes 58 biopsy cases, 78 screening negative cases, and other "recalled" cases (for additional imaging procedures). We measured eight signal features from the effective REIS sweep of each breast. We applied a multi-feature based artificial neural network (ANN) to classify between "biopsy" and normal "non-biopsy" breasts. The ANN performance is evaluated using a leave-one-out validation method and ROC analysis. We conducted two experiments. The first experiment attempted to classify 58 "biopsy" breasts and 58 "non-biopsy" breasts acquired on 58 women

  5. Schumann Resonance on Mars: A Tool for the Investigation of the Electrical Properties of the Martian Environment

    NASA Astrophysics Data System (ADS)

    Kozakiewicz, Joanna; Kulak, Andrzej; Mlynarczyk, Janusz

    2013-04-01

    Schumann resonances (SR) are global resonances of electromagnetic waves in the range of extremely low frequencies (ELF) propagating in a planetary cavity. This spherical waveguide is formed by the ground and the lower ionosphere. SR are supposed to occur on Mars, although many electrical properties of the Martian environment are still not well-determined. One of the most important problems in the SR modeling on Mars is to estimate electrical properties of the Martian ground and their influence on ELF waves propagation. In our previous study we have developed an analytical model of the ground-ionosphere waveguide based on the characteristic electric and magnetic complex altitudes' formalism, which has allowed us to take into consideration the Martian two-layered ground. In this work we have carried out simulations in order to determine the influence of the electrical properties of the Martian cavity on ELF waves propagation. We obtained results for several cases in which different electrical properties associated with the Martian atmosphere and ground were considered. Particularly we discussed the SR spectra obtained for the cases of low-conductive surface layers, and high-conductive subsurface layers of various depth. In addition we estimated the threshold value for the volumetric size of hypothetic groundwater reservoirs above which they could be detected using the SR phenomenon. The results point out the importance of studying SR on Mars and the need for the in situ research on propagation of ELF waves in the Martian environment. The measurement of the resonance field on Mars is associated with a necessity to locate an ELF receiving system at the planetary surface. The heaviest part of such equipment are two orthogonal magnetic antennas of an adequately high sensitivity. We have discussed the issue of sending such instruments to Mars. We also proposed an uncomplicated way to measure the electrical properties of the Martian cavity.

  6. Considerations on the Design of a Molecular Frequency Standard Based on the Molecular Beam Electric Resonance Method

    NASA Technical Reports Server (NTRS)

    Hughes, Vernon W.

    1959-01-01

    The use of a rotational state transition as observed by the molecular beam electric resonance method is discussed as a possible frequency standard particularly in the millimeter wavelength range. As a promising example the 100 kMc transition between the J = 0 and J = 1 rotational states of Li 6F19 is considered. The relative insensitivity of the transition frequency to external electric and magnetic fields and the low microwave power requirements appear favorable; the small fraction of the molecular beam that is in a single rotational state is a limiting factor.

  7. Experimental verification of isotropic radiation from a coherent dipole source via electric-field-driven LC resonator metamaterials.

    PubMed

    Tichit, Paul-Henri; Burokur, Shah Nawaz; Qiu, Cheng-Wei; de Lustrac, André

    2013-09-27

    It has long been conjectured that isotropic radiation by a simple coherent source is impossible due to changes in polarization. Though hypothetical, the isotropic source is usually taken as the reference for determining a radiator's gain and directivity. Here, we demonstrate both theoretically and experimentally that an isotropic radiator can be made of a simple and finite source surrounded by electric-field-driven LC resonator metamaterials designed by space manipulation. As a proof-of-concept demonstration, we show the first isotropic source with omnidirectional radiation from a dipole source (applicable to all distributed sources), which can open up several possibilities in axion electrodynamics, optical illusion, novel transformation-optic devices, wireless communication, and antenna engineering. Owing to the electric- field-driven LC resonator realization scheme, this principle can be readily applied to higher frequency regimes where magnetism is usually not present. PMID:24116780

  8. Selective Tuning of a Particular Chemical Reaction on Surfaces through Electrical Resonance: An ab Initio Molecular Dynamics Study.

    PubMed

    Yousaf, Masood; Shin, Dongbin; Ruoff, Rodney; Park, Noejung

    2015-12-17

    We used ab initio molecular dynamics (AIMD) to investigate the effect of a monochromatic oscillating electric field in resonance with a particular molecular vibration on surfaces. As a case study, AIMD simulations were carried out for hydroxyl functional groups on graphene. When the frequency of the applied field matches with the C-OH vibration frequency, the amplitude is monotonically amplified, leading to a complete desorption from the surface, overcoming the substantial barrier. This suggests the possibility of activating a particular bond without damaging the remaining surface. We extended this work to the case of the amination of sp(2)-bonded carbon surfaces and discussed the general perspective that, in general, an unfavorable chemical process can be activated by applying an external electric field with an appropriate resonance frequency. PMID:26634785

  9. A dynamically tunable terahertz metamaterial absorber based on an electrostatic MEMS actuator and electrical dipole resonator array

    NASA Astrophysics Data System (ADS)

    Hu, Fangrong; Xu, Ningning; Wang, Weiming; Wang, Yue'e.; Zhang, Wentao; Han, Jiaguang; Zhang, Weili

    2016-02-01

    We experimentally demonstrate a dynamically tunable terahertz (THz) metamaterial absorber based on an electrostatic microelectromechanical systems (MEMS) actuator and electrical dipole resonator array. The absorption of the THz wave is mainly a result of the electrical dipole resonance, which shows a tunable performance on demand. By preforming the finite integral technique, we discovered that the central absorption frequency and the amplitude can be simultaneously tuned by the applied voltage U. Characterized by a white light interferometer and a THz time domain spectroscopy system, our THz absorber is measured to show a modulation of the central frequency and the amplitude to about 10% and 20%, respectively. The experimental results show good agreement with the simulation. This dynamically tunable absorber has potential applications on THz filters, modulators and controllers.

  10. Conductor disc used to suppress spurious mode and enhance electric coupling in a dielectric loaded combline resonator

    NASA Astrophysics Data System (ADS)

    Pholele, T. M.; Chuma, J. M.

    2016-03-01

    The effects of conductor disc in a dielectric loaded combline resonator on its spurious performance, unloaded quality factor (Qu), and coupling coefficients are analysed using a commercial electromagnetic software package CST Microwave Studio (CST MWS). The disc improves the spurious free band but simultaneously deteriorates the Qu. The presence of the disc substantially improves the electric coupling by a factor of 1.891 for an aperture opening of 12 mm, while it has insignificant effect on the magnetic coupling.

  11. Radial electric field generated by resonant trapped electron pinch with radio frequency injection in a tokamak plasma

    SciTech Connect

    Gao Zhe; Fisch, N. J.; Qin Hong

    2011-08-15

    Radial electric fields in tokamaks can be generated by charge accumulation due to a resonant trapped electron pinch effect. The radial field can then drive a toroidal flow. This resonant pinch effect was evaluated for the current-drive scheme that diffused electrons in the direction parallel to the toroidal field. It was found that, for typical tokamak parameters, to generate a radial electric field on the order of 100 kV/m, an rf power density on the order of kW/m{sup 3} is required. This power, absorbed by trapped electrons, is a small fraction of rf power density for current drive which is absorbed by passing electrons. However, according to the Landau resonant mechanism, the fraction of the momentum to trapped electrons decays exponentially with the square of the parallel phase velocity of the wave; therefore, the power absorbed at lower resonant velocities is the key. On the other hand, the redistribution of the current profile, due to rf current, decreases the local poloidal field and may reduce the particle transport significantly. It can relax the requirement of momentum deposited to trapped electrons, and, at the same time, contribute to explain the strongly correlation between the rotation and the driven current observed in experiments.

  12. Electrically compensated Fourier transform ion cyclotron resonance cell for complex mixture mass analysis.

    PubMed

    Kaiser, Nathan K; Savory, Joshua J; McKenna, Amy M; Quinn, John P; Hendrickson, Christopher L; Marshall, Alan G

    2011-09-01

    Complex natural organic mixtures such as petroleum require ultrahigh mass spectral resolution to separate and identify thousands of elemental compositions. Here, we incorporate a custom-built, voltage-compensated ICR cell for Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS), based on a prior design by Tolmachev to produce optimal mass resolution. The compensated ICR cell installed in a custom-built 9.4 T FTICR mass spectrometer consists of seven cylindrical segments with axial proportions designed to generate a dc trapping potential that approaches an ideal three-dimensional axial quadrupolar potential. However, the empirically optimized compensation voltages do not correspond to the most quadrupolar trapping field. The compensation electrodes minimize variation in the reduced cyclotron frequency by balancing imperfections in the magnetic and electric field. The optimized voltages applied to compensation electrodes preserve ion cloud coherence for longer transient duration by approximately a factor of 2, enabling separation and identification of isobaric species (compounds with the same nominal mass but different exact mass) common in petroleum, such as C(3) vs SH(4) (separated by 3.4 mDa) and SH(3)(13)C vs (12)C(4) (separated by 1.1 mDa). The improved performance of the ICR cell provides more symmetric peak shape and better mass measurement accuracy. A positive ion atmospheric pressure photoionization (APPI) petroleum spectrum yields more than 26,000 assigned peaks, Fourier-limited resolving power of 800,000 at m/z 500 (6.6 s transient duration), and 124 part per billion root mean square (rms) error. The tunability of the compensation electrodes is critical for optimal performance. PMID:21838231

  13. Multitarget, quantitative nanoplasmonic electrical field-enhanced resonating device (NE2RD) for diagnostics.

    PubMed

    Inci, Fatih; Filippini, Chiara; Baday, Murat; Ozen, Mehmet Ozgun; Calamak, Semih; Durmus, Naside Gozde; Wang, ShuQi; Hanhauser, Emily; Hobbs, Kristen S; Juillard, Franceline; Kuang, Ping Ping; Vetter, Michael L; Carocci, Margot; Yamamoto, Hidemi S; Takagi, Yuko; Yildiz, Umit Hakan; Akin, Demir; Wesemann, Duane R; Singhal, Amit; Yang, Priscilla L; Nibert, Max L; Fichorova, Raina N; Lau, Daryl T-Y; Henrich, Timothy J; Kaye, Kenneth M; Schachter, Steven C; Kuritzkes, Daniel R; Steinmetz, Lars M; Gambhir, Sanjiv S; Davis, Ronald W; Demirci, Utkan

    2015-08-11

    Recent advances in biosensing technologies present great potential for medical diagnostics, thus improving clinical decisions. However, creating a label-free general sensing platform capable of detecting multiple biotargets in various clinical specimens over a wide dynamic range, without lengthy sample-processing steps, remains a considerable challenge. In practice, these barriers prevent broad applications in clinics and at patients' homes. Here, we demonstrate the nanoplasmonic electrical field-enhanced resonating device (NE(2)RD), which addresses all these impediments on a single platform. The NE(2)RD employs an immunodetection assay to capture biotargets, and precisely measures spectral color changes by their wavelength and extinction intensity shifts in nanoparticles without prior sample labeling or preprocessing. We present through multiple examples, a label-free, quantitative, portable, multitarget platform by rapidly detecting various protein biomarkers, drugs, protein allergens, bacteria, eukaryotic cells, and distinct viruses. The linear dynamic range of NE(2)RD is five orders of magnitude broader than ELISA, with a sensitivity down to 400 fg/mL This range and sensitivity are achieved by self-assembling gold nanoparticles to generate hot spots on a 3D-oriented substrate for ultrasensitive measurements. We demonstrate that this precise platform handles multiple clinical samples such as whole blood, serum, and saliva without sample preprocessing under diverse conditions of temperature, pH, and ionic strength. The NE(2)RD's broad dynamic range, detection limit, and portability integrated with a disposable fluidic chip have broad applications, potentially enabling the transition toward precision medicine at the point-of-care or primary care settings and at patients' homes. PMID:26195743

  14. Multitarget, quantitative nanoplasmonic electrical field-enhanced resonating device (NE2RD) for diagnostics

    PubMed Central

    Inci, Fatih; Filippini, Chiara; Ozen, Mehmet Ozgun; Calamak, Semih; Durmus, Naside Gozde; Wang, ShuQi; Hanhauser, Emily; Hobbs, Kristen S.; Juillard, Franceline; Kuang, Ping Ping; Vetter, Michael L.; Carocci, Margot; Yamamoto, Hidemi S.; Takagi, Yuko; Yildiz, Umit Hakan; Akin, Demir; Wesemann, Duane R.; Singhal, Amit; Yang, Priscilla L.; Nibert, Max L.; Fichorova, Raina N.; Lau, Daryl T.-Y.; Henrich, Timothy J.; Kaye, Kenneth M.; Schachter, Steven C.; Kuritzkes, Daniel R.; Steinmetz, Lars M.; Gambhir, Sanjiv S.; Davis, Ronald W.; Demirci, Utkan

    2015-01-01

    Recent advances in biosensing technologies present great potential for medical diagnostics, thus improving clinical decisions. However, creating a label-free general sensing platform capable of detecting multiple biotargets in various clinical specimens over a wide dynamic range, without lengthy sample-processing steps, remains a considerable challenge. In practice, these barriers prevent broad applications in clinics and at patients’ homes. Here, we demonstrate the nanoplasmonic electrical field-enhanced resonating device (NE2RD), which addresses all these impediments on a single platform. The NE2RD employs an immunodetection assay to capture biotargets, and precisely measures spectral color changes by their wavelength and extinction intensity shifts in nanoparticles without prior sample labeling or preprocessing. We present through multiple examples, a label-free, quantitative, portable, multitarget platform by rapidly detecting various protein biomarkers, drugs, protein allergens, bacteria, eukaryotic cells, and distinct viruses. The linear dynamic range of NE2RD is five orders of magnitude broader than ELISA, with a sensitivity down to 400 fg/mL This range and sensitivity are achieved by self-assembling gold nanoparticles to generate hot spots on a 3D-oriented substrate for ultrasensitive measurements. We demonstrate that this precise platform handles multiple clinical samples such as whole blood, serum, and saliva without sample preprocessing under diverse conditions of temperature, pH, and ionic strength. The NE2RD’s broad dynamic range, detection limit, and portability integrated with a disposable fluidic chip have broad applications, potentially enabling the transition toward precision medicine at the point-of-care or primary care settings and at patients’ homes. PMID:26195743

  15. Coherent dipole-dipole coupling between two single Rydberg atoms at an electrically-tuned Förster resonance

    NASA Astrophysics Data System (ADS)

    Ravets, Sylvain; Labuhn, Henning; Barredo, Daniel; Béguin, Lucas; Lahaye, Thierry; Browaeys, Antoine

    2014-12-01

    Resonant energy transfers, the non-radiative redistribution of an electronic excitation between two particles coupled by the dipole-dipole interaction, lie at the heart of a variety of phenomena, notably photosynthesis. In 1948, Förster established the theory of fluorescence resonant energy transfer (FRET) between broadband, nearly-resonant donors and acceptors. The 1/R6 scaling of the energy transfer rate, where R is the distance between particles, enabled widespread use of FRET as a `spectroscopic ruler’ for determining nanometric distances in biomolecules. The underlying mechanism is a coherent dipolar coupling between particles, as recognized in the early days of quantum mechanics, but this coherence has not been directly observed so far. Here we study, spectroscopically and in the time domain, the coherent, dipolar-induced exchange of excitations between two Rydberg atoms separated by up to 15 μm, and brought into resonance by applying an electric field. Coherent oscillation of the system between two degenerate pair states then occurs at a frequency scaling as 1/R3, the hallmark of resonant dipole-dipole interactions. Our results not only demonstrate, at the fundamental level of two atoms, the basic mechanism underlying FRET, but also open exciting prospects for active tuning of strong, coherent interactions in quantum many-body systems.

  16. Toward single atom qubits on a surface: Pump-probe spectroscopy and electrically-driven spin resonance

    NASA Astrophysics Data System (ADS)

    Paul, William

    We will discuss the characterization of spin dynamics by pump-probe spectroscopy and the use of gigahertz-frequency electric fields to drive spin resonance of a Fe atom on a MgO/Ag(001) surface. In the spirit of this session, the technical challenges in applying a precise voltage to the tip sample junction across a wide radio-frequency bandwidth will be described. The energy relaxation time, T1, of single spins on surfaces can be measured by spin-polarized pump-probe STM (scanning tunneling microscopy). To date, the relaxation times reported for Fe-Cu dimers on Cu2N insulating films have been of the order ~100 ns. A three-order-of-magnitude enhancement of lifetime, to ~200 μs, was recently demonstrated for Co on a single-monolayer of MgO. Here, we report on the tailoring of the T1 lifetime of single Fe atoms on single- and multi- layer MgO films grown on Ag(001). Next, we demonstrate electron spin resonance of an individual single Fe atom, driven by a gigahertz-frequency electric field applied across the tip-sample junction, and detected by a spin-polarized tunneling current. The principle parameters of the spin resonance experiment, namely the phase coherence time T2 and the Rabi rate, are characterized for Fe atoms adsorbed to the monolayer MgO film.

  17. Quantum well micro-resonator optical modulator based on electrically controlled coupling

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Taylor, Geoff W.

    2013-09-01

    Micro-resonator optical modulators fabricated with Si/SiO2 planar waveguides have been reported for the optical interconnect application and the modulation is achieved by control of the resonant frequency through resonator index change. In these devices, thermal control is used to adjust/stabilize the resonant frequency and the input coupling constant. In this paper, an III-V based micro-resonator is described in which the modulation is achieved through voltage control of the input coupling parameter and the resonator frequency is adjusted/stabilized through control of the resonator index. This approach offers significant advantages for integrated circuit based optical connectivity. The modulator performance is analyzed via FDTD simulation with refractive index profiles based on measured absorption parameters. The performance is confirmed via MATLAB and a circuit based model for HSPICE is developed and run in a transient simulator to confirm the modulator speed and eye diagram characteristics yielding an extinction ratio of 10.7 dB, a bandwidth of 31 GHz and a energy consumption <2.5 fJ/bit for device dimensions of 28×4 µm2.

  18. A model for electrical resonance and frequency tuning in saccular hair cells of the bull-frog, Rana catesbeiana.

    PubMed

    Hudspeth, A J; Lewis, R S

    1988-06-01

    1. Electrical resonance in solitary hair cells was examined under several experimental conditions using the tight-seal recording technique in the whole-cell current-clamp mode. 2. Resonance was characterized by the frequency and quality factor of oscillations in membrane potential evoked by depolarizing current pulses. Oscillation frequency increased with depolarization, from about 90 Hz at the resting potential to a limiting value of about 250 Hz. The quality factor of the oscillations was a bell-shaped function of membrane potential that reached a maximum of up to 12.6 at a potential slightly positive to the resting potential. 3. Pharmacological experiments were performed to assess which of three ionic currents participate in electrical resonance. Reduction of the voltage-gated Ca2+ current (ICa) and the Ca2+-activated K+ current (IK(Ca)) by lowering the extracellular Ca2+ concentration, or reduction of IK(Ca) with tetraethylammonium ion (TEA) degraded the resonance. In contrast, blockade of the transient K+ current (IA) with 4-aminopyridine (4-AP) had no significant effect. 4. To test the sufficiency of the Ca2+ and the Ca2+-activated K+ currents to account for resonance, we developed a model using mathematical descriptions of the two currents derived in the preceding paper (Hudspeth & Lewis, 1988), with additional terms for leakage conductance and membrane capacitance. The model correctly predicts the oscillatory responses to applied current pulses, including the non-linear dependences of oscillation frequency and quality factor on membrane potential. 5. Simulations of current-clamp experiments in the presence of a reduced extracellular Ca2+ concentration or of TEA were generated respectively by decreasing the model's values for the maximal Ca2+ or Ca2+-activated K+ conductances. The model's predictions of membrane-potential oscillations under these conditions agree qualitatively with experimental results, providing further support for the model as a

  19. Electric field variations due to resonance between ground velocity and ions motion in the Earth's magnetic field

    NASA Astrophysics Data System (ADS)

    Matsushima, M.; Honkura, Y.; Kuriki, M.; Ogawa, Y.

    2011-12-01

    We have so far observed clear electric field variations coincident with the passage of seismic waves. Circular polarization of electric field is the distinguishing feature in this phenomenon which can be interpreted in terms of the so-called seismic dynamo effect proposed by Honkura et al. (2009). That is, circularly polarized electric field is caused by resonance-like motion of ion in groundwater under the Earth's magnetic field. Therefore, left-handed and right-handed circular polarizations, if seen towards the direction of the magnetic field, are associated with anions with negative charge and cations with positive charge, respectively. Such polarization may be inconsistent with seismoelectric signals due to the electrokinetic mechanism, because they are mainly found in the direction of transmission of seismic compressional waves, as pointed out by Strahser et al. (2007) who examined polarization of seismoelectric signals by recording the three components of electric field. However, even such circular polarization of electric field is somehow interpreted in terms of the electrokinetic mechanism. Therefore, further convincing evidence is required to support the seismic dynamo effect. On 25-26 July 2011, an experiment for studies of crustal seismic structure was made in central Japan. We carried out simultaneous observations of ground velocity and electric field on this occasion at three sites near a blasting point using 50 kg of dynamite; about 280 m east-southeast, about 190 m east, and about 360 m northwest from the blasting point. Taking into account typical frequencies of ground velocity for artificial earthquakes by blasting higher than those for natural earthquakes, we used data loggers with sampling rate of 1 kHz and could obtain the waveforms of ground velocity and electric field very clearly. We show characteristics of electric field variations, their dependence of azimuth angle with respect to the blasting point, and frequency response functions.

  20. Interface defects in SiC power MOSFETs - An electrically detected magnetic resonance study based on spin dependent recombination

    SciTech Connect

    Gruber, Gernot; Hadley, Peter; Koch, Markus; Peters, Dethard; Aichinger, Thomas

    2014-02-21

    This study presents electrically detected magnetic resonance (EDMR) measurements on a silicon carbide (SiC) MOSFET having the structure of a double-diffused silicon MOSFET (DMOS). The resonance pattern of a SiC DMOS was measured by monitoring the change of the recombination current between the source/body and the drain. The amplitude of the response has a maximum when the device is biased in depletion due to the equal concentrations of electrons and holes at the interface resulting in the most efficient recombination. The measured anisotropic g-tensor has axial symmetry with g{sub ∥} = 2.0051(4) (B ‖ c-axis), and g{sub ⊥} = 2.0029(4) (B⊥ c-axis) and the pattern shows several hyperfine (HF) peaks. We tentatively identify the observed defect as a silicon vacancy located directly at the interface.

  1. Analysis of symmetry breaking configurations in metal nanocavities: Identification of resonances for generating high-order magnetic modes and multiple tunable magnetic-electric Fano resonances

    NASA Astrophysics Data System (ADS)

    Wang, Liancheng; Liu, Zhiqiang; Yi, Xiaoyan; Zhang, Yiyun; Li, Hongjian; Li, Jinmin; Wang, Guohong

    2016-05-01

    A systematic investigation of the effects of symmetry breaking and the generation of Fano resonances in metal nanocavities is still lacking. In this work, we investigate the plasmonic properties of ring/disk silver nanocavities of various symmetry-breaking configurations. We find that multiple higher-order magnetic modes can be excited and that the quadrupole (Q) mode can even become dominant in a weakly asymmetric split ring. Magnetic-electric Fano resonances in weakly split-ring/disk nanocavities can be adjusted by tuning geometric parameters, such as the angle of the split, the width of the ring, the diameter of the ring, the center offset, and the number of superradiant antenna disks. The potential use of these multiple modes of ring/disk-based nanocavities in biosensing is evaluated by calculating the figure of merit and the contrast ratio. Our results correlate the various symmetry-breaking configurations with their plasmonic properties. The results will aid in the design of metal nanocavities for plasmonic applications.

  2. Electrical detection of surface plasmon resonance phenomena by a photoelectronic device integrated with gold nanoparticle plasmon antenna

    NASA Astrophysics Data System (ADS)

    Hashimoto, Tatsuya; Fukunishi, Yurie; Zheng, Bin; Uraoka, Yukiharu; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

    2013-02-01

    We have proposed a concept of a photoelectronic hybrid device utilizing gold nanoparticles (GNPs), which are supposed to function not only as the plasmon antenna but also as the sensing part. The photocurrent in the fabricated device, consisting of a transparent Nb-doped TiO2 channel and Au electrodes, was enhanced more than eight times at a specific wavelength with GNP arrays located between the electrodes, indicating that surface plasmon resonance was electrically detected with the hybrid device. This result will open new doors for ultra-small biosensor chips integrated with multi-functional solid-state devices.

  3. Electrically tunable liquid crystal laser using a nanoimprinted indium-tin-oxide electrode as a distributed feedback resonator.

    PubMed

    Yoon, Kyung Won; Ha, Na Young

    2016-01-11

    We demonstrated electrical tunability of a liquid crystal (LC) laser using a nanoimprinted indium-tin-oxide (ITO) film as a distributed feedback (DFB) resonator, a transparent electrode, and an alignment layer for LCs. From the field-induced reorientation of LCs and changes in effective refractive indices of guided laser modes, lasing emission is tuned by 6 nm at low applied voltage of 8.0 V. This is because the LC laser with the nanoimprinted ITO electrode has no additional insulating layers for lasing performance. The present system is based on the functional electrode and its active control provides various applications and advances in laser technology. PMID:26832281

  4. Electrical and electron paramagnetic resonance spectroscopy characterization of Mn-doped nanostructured TiO2 for capacitor applications

    NASA Astrophysics Data System (ADS)

    Vazquez-Reina, Rafael; Chao, Sheng; Petrovsky, Vladimir; Dogan, Fatih; Greenbaum, Steven

    2012-07-01

    Nanostructured TiO2 has shown promise as a dielectric material for high energy density ceramic capacitors because of its high dielectric breakdown strength and dielectric constant. Strategies to increase the insulation resistance or to reduce the leakage current of TiO2 include doping with transition metal ions. It is shown that Mn doping followed by an appropriate thermal treatment increases the grain boundary resistivity significantly and lowers the dielectric loss. Electrical measurements along with electron paramagnetic resonance and scanning electron microscopy of Mn-doped nanoscopic TiO2 demonstrate that sintering at 900 °C leads to optimal electrical properties that are correlated with a non-uniform distribution of dopant ions, concentrated at the grain boundaries. Nanostructured TiO2 dielectrics with improved insulation resistance are promising for the development of higher energy density capacitors.

  5. Experimental evaluation of electrical conductivity imaging of anisotropic brain tissues using a combination of diffusion tensor imaging and magnetic resonance electrical impedance tomography

    NASA Astrophysics Data System (ADS)

    Sajib, Saurav Z. K.; Jeong, Woo Chul; Kyung, Eun Jung; Kim, Hyun Bum; Oh, Tong In; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

    2016-06-01

    Anisotropy of biological tissues is a low-frequency phenomenon that is associated with the function and structure of cell membranes. Imaging of anisotropic conductivity has potential for the analysis of interactions between electromagnetic fields and biological systems, such as the prediction of current pathways in electrical stimulation therapy. To improve application to the clinical environment, precise approaches are required to understand the exact responses inside the human body subjected to the stimulated currents. In this study, we experimentally evaluate the anisotropic conductivity tensor distribution of canine brain tissues, using a recently developed diffusion tensor-magnetic resonance electrical impedance tomography method. At low frequency, electrical conductivity of the biological tissues can be expressed as a product of the mobility and concentration of ions in the extracellular space. From diffusion tensor images of the brain, we can obtain directional information on diffusive movements of water molecules, which correspond to the mobility of ions. The position dependent scale factor, which provides information on ion concentration, was successfully calculated from the magnetic flux density, to obtain the equivalent conductivity tensor. By combining the information from both techniques, we can finally reconstruct the anisotropic conductivity tensor images of brain tissues. The reconstructed conductivity images better demonstrate the enhanced signal intensity in strongly anisotropic brain regions, compared with those resulting from previous methods using a global scale factor.

  6. Integrated architecture for the electrical detection of plasmonic resonances based on high electron mobility photo-transistors

    NASA Astrophysics Data System (ADS)

    Sammito, Davide; de Salvador, Davide; Zilio, Pierfrancesco; Biasiol, Giorgio; Ongarello, Tommaso; Massari, Michele; Ruffato, Gianluca; Morpurgo, Margherita; Silvestri, Davide; Maggioni, Gianluigi; Bovo, Gianluca; Gaio, Michele; Romanato, Filippo

    2014-01-01

    We report the design of an integrated platform for on-chip electrical transduction of the surface plasmon resonance supported by a nanostructured metal grating. The latter is fabricated on the active area of a GaAs/AlGaAs photo-HEMT and simultaneously works as the electronic gate of the device. The gold plasmonic crystal has a V-groove profile and has been designed by numerical optical simulations. By showing that the numerical models accurately reproduce the phototransistors experimental response, we demonstrate that the proposed architecture is suitable for the development of a new class of compact and scalable SPR sensors.We report the design of an integrated platform for on-chip electrical transduction of the surface plasmon resonance supported by a nanostructured metal grating. The latter is fabricated on the active area of a GaAs/AlGaAs photo-HEMT and simultaneously works as the electronic gate of the device. The gold plasmonic crystal has a V-groove profile and has been designed by numerical optical simulations. By showing that the numerical models accurately reproduce the phototransistors experimental response, we demonstrate that the proposed architecture is suitable for the development of a new class of compact and scalable SPR sensors. Electronic supplementary information (ESI) available: HEMTs optical response, device fabrication flow chart, estimate of device resolution based on numerical simulations, synthesis of thiolated biotin, biotin functionalization and avidin binding procedure. See DOI: 10.1039/c3nr04666d

  7. Sensor applications of soft magnetic materials based on magneto-impedance, magneto-elastic resonance and magneto-electricity.

    PubMed

    García-Arribas, Alfredo; Gutiérrez, Jon; Kurlyandskaya, Galina V; Barandiarán, José M; Svalov, Andrey; Fernández, Eduardo; Lasheras, Andoni; de Cos, David; Bravo-Imaz, Iñaki

    2014-01-01

    The outstanding properties of selected soft magnetic materials make them successful candidates for building high performance sensors. In this paper we present our recent work regarding different sensing technologies based on the coupling of the magnetic properties of soft magnetic materials with their electric or elastic properties. In first place we report the influence on the magneto-impedance response of the thickness of Permalloy films in multilayer-sandwiched structures. An impedance change of 270% was found in the best conditions upon the application of magnetic field, with a low field sensitivity of 140%/Oe. Second, the magneto-elastic resonance of amorphous ribbons is used to demonstrate the possibility of sensitively measuring the viscosity of fluids, aimed to develop an on-line and real-time sensor capable of assessing the state of degradation of lubricant oils in machinery. A novel analysis method is shown to sensitively reveal the changes of the damping parameter of the magnetoelastic oscillations at the resonance as a function of the oil viscosity. Finally, the properties and performance of magneto-electric laminated composites of amorphous magnetic ribbons and piezoelectric polymer films are investigated, demonstrating magnetic field detection capabilities below 2.7 nT. PMID:24776934

  8. Sensor Applications of Soft Magnetic Materials Based on Magneto-Impedance, Magneto-Elastic Resonance and Magneto-Electricity

    PubMed Central

    García-Arribas, Alfredo; Gutiérrez, Jon; Kurlyandskaya, Galina V.; Barandiarán, José M.; Svalov, Andrey; Fernández, Eduardo; Lasheras, Andoni; de Cos, David; Bravo-Imaz, Iñaki

    2014-01-01

    The outstanding properties of selected soft magnetic materials make them successful candidates for building high performance sensors. In this paper we present our recent work regarding different sensing technologies based on the coupling of the magnetic properties of soft magnetic materials with their electric or elastic properties. In first place we report the influence on the magneto-impedance response of the thickness of Permalloy films in multilayer-sandwiched structures. An impedance change of 270% was found in the best conditions upon the application of magnetic field, with a low field sensitivity of 140%/Oe. Second, the magneto-elastic resonance of amorphous ribbons is used to demonstrate the possibility of sensitively measuring the viscosity of fluids, aimed to develop an on-line and real-time sensor capable of assessing the state of degradation of lubricant oils in machinery. A novel analysis method is shown to sensitively reveal the changes of the damping parameter of the magnetoelastic oscillations at the resonance as a function of the oil viscosity. Finally, the properties and performance of magneto-electric laminated composites of amorphous magnetic ribbons and piezoelectric polymer films are investigated, demonstrating magnetic field detection capabilities below 2.7 nT. PMID:24776934

  9. Spoof surface plasmons resonance effect and tunable electric response of improved metamaterial in the terahertz regime

    NASA Astrophysics Data System (ADS)

    Wang, Yue; Zhang, Li-Ying; Mei, Jin-Shuo; Zhang, Wen-Chao; Tong, Yi-Jing

    2015-12-01

    We propose an improved design and numerical study of an optimized tunable plasmonics artificial material resonator in the terahertz regime. We demonstrate that tunability can be realized with a transmission intensity as much as ˜61% in the lower frequency resonance, which is implemented through the effect of photoconductive switching under photoexcitation. In the higher frequency resonance, we show that spoof surface plasmons along the interface of metal/dielectric provide new types of electromagnetic resonances. Our approach opens up possibilities for the interface of metamaterial and plasmonics to be applied to optically tunable THz switching. Project supported by the National Natural Science Foundation of China (Grant No. 61201075), the Natural Science Foundation of Heilongjiang Province, China (Grant No. F2015039), the Young Scholar Project of Heilongjiang Provincial Education Bureau, China (Grant No. 1254G021), the China Postdoctoral Science Foundation (Grant No. 2012M511507), and the Science Funds for the Young Innovative Talents of Harbin University of Science and Technology, China (Grant No. 201302).

  10. Electrical detection of ferromagnetic resonance in single layers of permalloy: Evidence of magnonic charge pumping

    NASA Astrophysics Data System (ADS)

    Azevedo, A.; Cunha, R. O.; Estrada, F.; Alves Santos, O.; Mendes, J. B. S.; Vilela-Leão, L. H.; Rodríguez-Suárez, R. L.; Rezende, S. M.

    2015-07-01

    The generation of a DC voltage in single layers of permalloy (Ni81Fe19 ) when the magnetization is undergoing ferromagnetic resonance is investigated in a series of samples with thickness varying from 4.0 to 150 nm. By sweeping the external field at a fixed microwave frequency, we measure a DC voltage at the ends of the layer as a function of the in-plane angle for each sample. The asymmetric voltage signal generated at the resonance field is a superposition of symmetric Lorentzian and antisymmetric Lorentzian derivative line shapes. The in-plane dependence of both symmetric and antisymmetric signals cannot be explained as due to spin rectification (SRE) only. The results are well explained by a model that takes into account in addition to the SRE the contribution of the recent discovered effect of magnonic charge pumping that converts magnetization dynamics into charge current by means of the spin orbit coupling.

  11. Ferromagnetic resonance shifts from electric fields: Field-enhanced screening charge in ferromagnet/ferroelectric multilayers

    NASA Astrophysics Data System (ADS)

    Gunawan, V.; Stamps, R. L.

    2012-03-01

    We calculate standing spin wave frequencies in a multilayer which unit cell is a trilayer comprised of a ferromagnet, a ferroelectric, and a normal metal. An applied voltage enhances the polarization of the ferroelectric and increases the magnetic moment at one interface through spin polarization and charge transfer. We show that the induced surface magnetism results in shifts of resonance and standing spin wave mode frequencies. A new resonance peak is predicted, associated with a strongly localized surface moment. Estimates are provided using parameters appropriate to the ferroelectric BaTiO3 and four different ferromagnetic metals, including a Heusler alloy (Fe, CrO2, permalloy, and Co2MnGe). The calculations use an entire-cell effective-medium approximation that takes into account the polarization profile in the ferroelectric. The metallic ferromagnetic electrode is treated as a real metal, and the depolarization field is included in the determination of polarization in the ferroelectric.

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

    SciTech Connect

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

    2014-07-15

    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. Magnetic resonance imaging of morphological and functional changes of the uterus induced by sacral surface electrical stimulation.

    PubMed

    Ogura, Takahide; Murakami, Takashi; Ozawa, Yuka; Seki, Kazunori; Handa, Yasunobu

    2006-01-01

    The purpose of this study is to examine the morphological and kinematical changes of the uterus induced by electrical stimulation applied to the skin just above the second and fourth posterior sacral foramens (sacral surface electrical stimulation [ssES]) in 26 healthy subjects. Out of them, eight subjects who had severe pain subjectively during every menstruation received ssES just in menstruation. Morphological and functional changes of the uterus were examined by using T2-weighted magnetic resonance (MR) imaging and T1-weighted MR cinematography, respectively. Cyclic electrical stimulation for 15 min with 5 sec ON and 5 sec OFF was applied just before MR scanning. A decrease in thickness of the muscular layer of the uterus was observed in every subject after ssES for 15 min and was significant as compared with the thickness before ssES. Periodic uterine movement during menstruation was observed in the subjects with severe menstrual pain in MR cine and the power spectrum analysis of the movement showed a marked decrease in peak power and frequency after ssES treatment. We conclude that ssES causes a reduction of static muscle tension of the uterus in all menstrual cycle periods and suppression of uterine peristalsis during menstruation in the subjects with severe menstrual pain. Possible neural mechanisms for these static and dynamic effects of ssES on the uterus at spinal level are discussed. PMID:16340175

  14. Electron cyclotron resonant multicusp magnetic field microwave plasma source for electric propulsion

    SciTech Connect

    Dahimene, M.; Mahoney, L.; Asmussen, J.

    1987-05-01

    The development of electrodeless microwave ion and plasma sources has been a recent, very active research project at Michigan State University. The results are efficient, compact microwave discharge configurations that operate at low pressures (0.5 mtorr to 100 mtorr) and efficiently produce low energy ions and free radicals and broad ion beams for oxidation, deposition, and etching experiments. The microwave discharge technology developed for these applications may be useful for application in electric propulsion. This paper reviews this microwave applicator technology and indicates how it may be extended to higher power levels and applied to electric propulsion systems. 12 references.

  15. Resonant phase jump with enhanced electric field caused by surface phonon polariton in terahertz region.

    PubMed

    Okada, Takanori; Nagai, Masaya; Tanaka, Koichiro

    2008-04-14

    We investigated surface phonon polariton in cesium iodide with terahertz time-domain attenuated total reflection method in Otto configuration, which gives us both information on amplitude and phase of surface electromagnetic mode directly. Systematic experiments with precise control of the distance between a prism and an active material show that the abrupt change of pi-phase jump appears sensitively under polariton picture satisfied when the local electric field at the interface becomes a maximum. This demonstration will open the novel phase-detection terahertz sensor using the active medium causing the strong enhancement of terahertz electric field. PMID:18542668

  16. Some nuclear magnetic resonance studies of the effect of electric field on lipid dispersions

    NASA Astrophysics Data System (ADS)

    Osman, Peter Damien

    1997-11-01

    A method has been developed for studying, by NMR spectroscopy, the effect of pulsed electric fields on lipid aggregate structures such as bilayers and inverted hexagonal tubules as well as on the lipid conformation. Sample conductivity and ohmic heating caused the lipid to dehydrate under some test conditions and led to the use of glycerol as a substitute for water in membrane dispersions. It was found possible to produce aligned lipid multilayers which appeared very similar in spectral character to those obtained using water and lipid. Such membranes were more stable and possessed low ionic conduction. Additionally, it was possible to use the temperature dependence of chemical shifts in the NMR spectra to measure the ohmic heating effects resulting from the application of electric field to a lipid multilayer stack. The effect of electric fields on several lipids were investigated, including: egg yolk phosphatidylcholine, dioleoylphosphatidylcholine, dioleoylphosphatidylethanolamine and dimyristoylphosphatidylcholine; together with mixtures of these lipids. Additionally lipids in which the voltage dependent ionophore alamethicin was included were tested. It was observed that electric fields below 16 MV/m had little direct effect on the conformation of lipid molecules, although slight changes were observed in the lipid headgroup region of lipid-glycerol multilayers. However, alterations in the long range order were observed including the rotation of lipid tubules in the inverted hexagonal phase; a lowering of the lamellar to inverted hexagonal phase transition temperature, and alteration of the spectra from aligned lipid multilayers of mixed lipids to spectra consistent with a viscous isotropic phase. Analyses were carried out to predict the effect of electric field on lipid dispersions. These included a model for the dielectrophoretic reorientation of elongated structures. This model was tested using dioleoylphosphatidylethanolamine in the inverted hexagonal phase

  17. Comparison of birefringent electric split-ring resonator and meanderline structures as quarter-wave plates at terahertz frequencies.

    PubMed

    Strikwerda, Andrew C; Fan, Kebin; Tao, Hu; Pilon, Daniel V; Zhang, Xin; Averitt, Richard D

    2009-01-01

    We have fabricated a quarter-wave plate from a single layer of birefringent electric split-ring resonators (ELC). For comparison, an appropriately scaled double layer meanderline structure was fabricated. At the design frequency of 639 GHz, the ELC structure achieves 99.9% circular polarization while the meanderline achieves 99.6%. The me-anderline displays a larger bandwidth of operation, attaining over 99% circular polarization from 615 - 743 GHz, while the ELC achieves 99% from 626 - 660 GHz. However, both are broad enough for use with CW sources making ELCs a more attractive choice due to the ease of fabrication. Both samples are free standing with a total thickness of 70 microm for the meanderline structure and a mere 20 microm for the ELC highlighting the large degree of birefringence exhibited with metamaterial structures. PMID:19129881

  18. Physical stress testing of bovine jugular veins using magnetic resonance imaging, echocardiography and electrical velocimetry.

    PubMed

    Boethig, Dietmar; Ernst, Franziska; Sarikouch, Samir; Norozi, Kambiz; Lotz, Joachim; Opherk, Jan Patrick; Meister, Maren; Breymann, Thomas

    2010-06-01

    Bovine jugular veins (BJVs) (Contegra) are valve-bearing pulmonary artery substitutes. Their valves have higher profiles than human pulmonary valves; this might result in less optimal performance. Therefore, we investigated the impact of stress and undersizing on conduit performance with ergometry, echocardiography and magnetic resonance imaging (MRI). Between April 2007 and June 2008, 20 BJV recipients (age 7.9-19.6 years) underwent spiroergometry and subsequent echocardiography; after due rest, ergometry was repeated and followed by MRI during recovery. A year later, exams were repeated. Data was evaluated as follows: comparison of stress related maximal individual valve performance changes (magnetic resonance: exercise induced average stroke volume changes by 61+/-49%; mean insufficiency increased by 2% in patients with <1% rest insufficiency and by 8% after rest insufficiency of >10%; the average rest gradient of 24+/-11 mmHg rose to 40+/-20 mmHg), and stratification of pooled observations by regurgitation fraction, insufficiency grades and z-values (insufficiency rose with increasing heart rate and decreasing stroke volume; undersizing increased gradients during recovery by 7+/-0.7 mmHg/z-value). Contegras high-profile valves tolerate stress without performance drop. Stress induced changes of insufficiency and gradient were clinically not significant, but sufficient to distort examination results; therefore, constant examination conditions are indispensable for a correct follow-up. PMID:20479070

  19. Enhancement of Rydberg-mediated single-photon nonlinearities by electrically tuned Förster resonances

    PubMed Central

    Gorniaczyk, H.; Tresp, C.; Bienias, P.; Paris-Mandoki, A.; Li, W.; Mirgorodskiy, I.; Büchler, H. P.; Lesanovsky, I.; Hofferberth, S.

    2016-01-01

    Mapping the strong interaction between Rydberg atoms onto single photons via electromagnetically induced transparency enables manipulation of light at the single-photon level and few-photon devices such as all-optical switches and transistors operated by individual photons. Here we demonstrate experimentally that Stark-tuned Förster resonances can substantially increase this effective interaction between individual photons. This technique boosts the gain of a single-photon transistor to over 100, enhances the non-destructive detection of single Rydberg atoms to a fidelity beyond 0.8, and enables high-precision spectroscopy on Rydberg pair states. On top, we achieve a gain larger than 2 with gate photon read-out after the transistor operation. Theory models for Rydberg polariton propagation on Förster resonance and for the projection of the stored spin-wave yield excellent agreement to our data and successfully identify the main decoherence mechanism of the Rydberg transistor, paving the way towards photonic quantum gates. PMID:27515278

  20. On the Modeling of Electrical Response of SAW Resonator-based Sensors Versus Temperature

    NASA Astrophysics Data System (ADS)

    Ballandras, S.; Laroche, T.; Courjon, E.; Daniau, W.; Baron, T.; Garcia, J.; Alzuaga, S.

    Surface acoustic wave (SAW) resonators built on Langasite (LGS) are capable to withstand temperature in excess of 900∘ C and demonstration of wireless interrogation of packaged sensors up to 700∘ C has been achieved for several tens of hours. These promising results emphasize the need for an accurate characterization of the raw material in order to design SAW resonators with a high level of confidence in the prediction, particularly concerning the temperature coefficient of frequency (TCF). Several data set have been published for LGS, offering prediction capabilities but also a significant level of data dispersion. Therefore, the evaluation of the effective thermal properties of SAW under periodic gratings turns out less robust than expected. Based also on published data and on measurements achieved within the SAWHOT project, harmonic admittance calculations have been achieved for deriving the evolution of mixed matrix parameters allowing for accurate SAW device simulation at any temperature. Adjusting the temperature coefficients then yield improved sets of material coefficients for design purpose. Using these data, we have demonstrated the possibility to develop a differential temperature sensor operating at temperature up to 600°C.

  1. Enhancement of Rydberg-mediated single-photon nonlinearities by electrically tuned Förster resonances.

    PubMed

    Gorniaczyk, H; Tresp, C; Bienias, P; Paris-Mandoki, A; Li, W; Mirgorodskiy, I; Büchler, H P; Lesanovsky, I; Hofferberth, S

    2016-01-01

    Mapping the strong interaction between Rydberg atoms onto single photons via electromagnetically induced transparency enables manipulation of light at the single-photon level and few-photon devices such as all-optical switches and transistors operated by individual photons. Here we demonstrate experimentally that Stark-tuned Förster resonances can substantially increase this effective interaction between individual photons. This technique boosts the gain of a single-photon transistor to over 100, enhances the non-destructive detection of single Rydberg atoms to a fidelity beyond 0.8, and enables high-precision spectroscopy on Rydberg pair states. On top, we achieve a gain larger than 2 with gate photon read-out after the transistor operation. Theory models for Rydberg polariton propagation on Förster resonance and for the projection of the stored spin-wave yield excellent agreement to our data and successfully identify the main decoherence mechanism of the Rydberg transistor, paving the way towards photonic quantum gates. PMID:27515278

  2. Impact of nanomechanical resonances on lasing from electrically pumped quantum dot micropillars

    NASA Astrophysics Data System (ADS)

    Czerniuk, T.; Tepper, J.; Akimov, A. V.; Unsleber, S.; Schneider, C.; Kamp, M.; Höfling, S.; Yakovlev, D. R.; Bayer, M.

    2015-01-01

    We use a picosecond acoustics technique to modulate the laser output of electrically pumped GaAs/AlAs micropillar lasers with InGaAs quantum dots. The modulation of the emission wavelength takes place on the frequencies of the nanomechanical extensional and breathing (radial) modes of the micropillars. The amplitude of the modulation for various nanomechanical modes is different for every micropillar which is explained by a various elastic contact between the micropillar walls and polymer environment.

  3. CW and pulsed electrically detected magnetic resonance spectroscopy at 263GHz/12T on operating amorphous silicon solar cells.

    PubMed

    Akhtar, W; Schnegg, A; Veber, S; Meier, C; Fehr, M; Lips, K

    2015-08-01

    Here we describe a new high frequency/high field continuous wave and pulsed electrically detected magnetic resonance (CW EDMR and pEDMR) setup, operating at 263GHz and resonance fields between 0 and 12T. Spin dependent transport in illuminated hydrogenated amorphous silicon p-i-n solar cells at 5K and 90K was studied by in operando 263GHz CW and pEDMR alongside complementary X-band CW EDMR. Benefiting from the superior resolution at 263GHz, we were able to better resolve EDMR signals originating from spin dependent hopping and recombination processes. 5K EDMR spectra were found to be dominated by conduction and valence band tail states involved in spin dependent hopping, with additional contributions from triplet exciton states. 90K EDMR spectra could be assigned to spin pair recombination involving conduction band tail states and dangling bonds as the dominating spin dependent transport process, with additional contributions from valence band tail and triplet exciton states. PMID:26112328

  4. Ferromagnetic Resonance Spin Pumping and Electrical Spin Injection in Silicon-Based Metal-Oxide-Semiconductor Heterostructures.

    PubMed

    Pu, Y; Odenthal, P M; Adur, R; Beardsley, J; Swartz, A G; Pelekhov, D V; Flatté, M E; Kawakami, R K; Pelz, J; Hammel, P C; Johnston-Halperin, E

    2015-12-11

    We present the measurement of ferromagnetic resonance (FMR-)driven spin pumping and three-terminal electrical spin injection within the same silicon-based device. Both effects manifest in a dc spin accumulation voltage V_{s} that is suppressed as an applied field is rotated to the out-of-plane direction, i.e., the oblique Hanle geometry. Comparison of V_{s} between these two spin injection mechanisms reveals an anomalously strong suppression of FMR-driven spin pumping with increasing out-of-plane field H_{app}^{z}. We propose that the presence of the large ac component to the spin current generated by the spin pumping approach, expected to exceed the dc value by 2 orders of magnitude, is the origin of this discrepancy through its influence on the spin dynamics at the oxide-silicon interface. This convolution, wherein the dynamics of both the injector and the interface play a significant role in the spin accumulation, represents a new regime for spin injection that is not well described by existing models of either FMR-driven spin pumping or electrical spin injection. PMID:26705647

  5. Noise-induced resonance-like phenomena in InP crystals embedded in fluctuating electric fields

    NASA Astrophysics Data System (ADS)

    Persano Adorno, D.; Pizzolato, N.; Spagnolo, B.

    2016-05-01

    We explore and discuss the complex electron dynamics inside a low-doped n-type InP bulk embedded in a sub-THz electric field, fluctuating for the superimposition of an external source of Gaussian correlated noise. The results presented in this study derive from numerical simulations obtained by means of a multi-valley Monte Carlo approach to simulate the nonlinear transport of electrons inside the semiconductor crystal. The electronic noise characteristics are statistically investigated by calculating the correlation function of the velocity fluctuations, its spectral density and the integrated spectral density, i.e. the total noise power, for different values of both amplitude and frequency of the driving oscillating electric field and for different correlation times of the field fluctuations. Our results show that the nonlinear response of electrons is strongly affected by the field fluctuations. In particular, crucially depending on the relationship between the correlation times of the external Gaussian noise and the timescales of complex phenomena involved in the electron dynamical behavior: (i) electrons self-organize among different valleys, giving rise to intrinsic noise suppression; (ii) this cooperative behavior causes the appearance of a resonance-like phenomenon in the noise spectra.

  6. Ferromagnetic Resonance Spin Pumping and Electrical Spin Injection in Silicon-Based Metal-Oxide-Semiconductor Heterostructures

    NASA Astrophysics Data System (ADS)

    Pu, Y.; Odenthal, P. M.; Adur, R.; Beardsley, J.; Swartz, A. G.; Pelekhov, D. V.; Flatté, M. E.; Kawakami, R. K.; Pelz, J.; Hammel, P. C.; Johnston-Halperin, E.

    2015-12-01

    We present the measurement of ferromagnetic resonance (FMR-)driven spin pumping and three-terminal electrical spin injection within the same silicon-based device. Both effects manifest in a dc spin accumulation voltage Vs that is suppressed as an applied field is rotated to the out-of-plane direction, i.e., the oblique Hanle geometry. Comparison of Vs between these two spin injection mechanisms reveals an anomalously strong suppression of FMR-driven spin pumping with increasing out-of-plane field Happz . We propose that the presence of the large ac component to the spin current generated by the spin pumping approach, expected to exceed the dc value by 2 orders of magnitude, is the origin of this discrepancy through its influence on the spin dynamics at the oxide-silicon interface. This convolution, wherein the dynamics of both the injector and the interface play a significant role in the spin accumulation, represents a new regime for spin injection that is not well described by existing models of either FMR-driven spin pumping or electrical spin injection.

  7. A theoretical resonant-tunnelling approach to electric-field effects in quasiperiodic Fibonacci GaAs-(Ga,Al)As semiconductor superlattices

    NASA Astrophysics Data System (ADS)

    Reyes-Gómez, E.; Perdomo-Leiva, C. A.; Oliveira, L. E.; de Dios-Leyva, M.

    1998-04-01

    A theoretical resonant-tunnelling approach is used in a detailed study of the electronic and transmission properties of quasiperiodic Fibonacci GaAs-(Ga,Al)As semiconductor superlattices, under applied electric fields. The theoretical scheme is based upon an exact solution of the corresponding Schroedinger equations in different wells and barriers, through the use of Airy functions, and a transfer-matrix technique. The calculated quasibound resonant energies agree quite well with previous theoretical parameter-based results within a tight-binding scheme, in the particular case of isolated Fibonacci building blocks. Theoretical resonant-tunnelling results for 0953-8984/10/16/009/img6 and 0953-8984/10/16/009/img7 generations of the quasiperiodic Fibonacci superlattice reveal the occurrence of anticrossings of the resonant levels with applied electric fields, together with the conduction- and valence-level wave function localization properties and electric-field-induced migration to specific regions of the semiconductor quasiperiodic heterostructure. Finally, theoretical resonant-tunnelling calculations for the interband transition energies are shown to be in quite good quantitative agreement with previously reported experimental photocurrent measurements.

  8. Electrical detection of ferromagnetic resonance in ferromagnet/n-GaAs heterostructures by tunneling anisotropic magnetoresistance

    SciTech Connect

    Liu, C.; Boyko, Y.; Geppert, C. C.; Christie, K. D.; Stecklein, G.; Crowell, P. A.; Patel, S. J.; Palmstrøm, C. J.

    2014-11-24

    We observe a dc voltage peak at ferromagnetic resonance (FMR) in samples consisting of a single ferromagnetic (FM) layer grown epitaxially on the n-GaAs (001) surface. The FMR peak is detected as an interfacial voltage with a symmetric line shape and is present in samples based on various FM/n-GaAs heterostructures, including Co{sub 2}MnSi/n-GaAs, Co{sub 2}FeSi/n-GaAs, and Fe/n-GaAs. We show that the interface bias voltage dependence of the FMR signal is identical to that of the tunneling anisotropic magnetoresistance (TAMR) over most of the bias range. Furthermore, we show how the precessing magnetization yields a dc FMR signal through the TAMR effect and how the TAMR phenomenon can be used to predict the angular dependence of the FMR signal. This TAMR-induced FMR peak can be observed under conditions where no spin accumulation is present and no spin-polarized current flows in the semiconductor.

  9. Tunable surface plasmon resonance and enhanced electrical conductivity of In doped ZnO colloidal nanocrystals

    NASA Astrophysics Data System (ADS)

    Ghosh, Sirshendu; Saha, Manas; de, S. K.

    2014-05-01

    We report a new synthesis process of colloidal indium (In) doped zinc oxide (ZIO) nanocrystals by a hot injection technique. By fine tuning the synthesis we reached the same nucleation temperature for indium oxide and zinc oxide which helped us to study a dopant precursor dependent In incorporation into the ZnO matrix by using different In sources. The dopant induced shape evolution changes the hexagonal pyramid structured ZnO to a platelet like structure upon 8% In doping. The introduction of trivalent In3+ into the ZnO lattice and consequent substitution of divalent Zn2+ generates free electrons in the conduction band which produces a plasmonic resonance in the infrared region. The electron concentration controls plasmon frequency as well as the band gap of host ZnO. The variation of the band gap and the modification of the conduction band have been explained by the Burstein-Moss effect and Mie's theory respectively. The In dopant changes the defect chemistry of pure ZnO nanocrystals which has been studied by photoluminescence and other spectroscopic measurements. The nanocrystals are highly stable in the organic medium and can be deposited as a crack free thin film on different substrates. Careful ligand exchange and thermal annealing of the spin cast film lead to a good conductive film (720 Ω per square to 120 Ω per square) with stable inherent plasmonic absorption in the infrared and 90% transmittance in the visible region. A temperature induced metal-semiconductor transition was found for doped ZnO nanocrystals. The transition temperature shifts to a lower temperature with increase of the doping concentration.We report a new synthesis process of colloidal indium (In) doped zinc oxide (ZIO) nanocrystals by a hot injection technique. By fine tuning the synthesis we reached the same nucleation temperature for indium oxide and zinc oxide which helped us to study a dopant precursor dependent In incorporation into the ZnO matrix by using different In sources. The

  10. On Planning and Exploiting Schumann Resonance Measurements for Monitoring the Electrical Productivity of Global Lightning Activity

    NASA Astrophysics Data System (ADS)

    Mushtak, V. C.; Williams, E.

    2010-12-01

    The spatial-temporal behavior of world-wide lightning activity can be effectively used as an indicator of various geophysical processes, the global climate change being of a special interest among them. Since it has been reliably established that the lightning activity presents a major source of natural electromagnetic background in the Schumann resonance (SR) frequency range (5 to 40 Hz), SR measurements provide a continuous flow of information about this globally distributed source, thus forming an informative basis for monitoring its behavior via an inversion of observations into the source’s properties. To have such an inversion procedure effective, there is a series of prerequisites to comply with when planning and realizing it: (a) a proper choice of observable parameters to be used in the inversion; (b) a proper choice of a forward propagation model that would be accurate enough to take into consideration the major propagation effects occurring between a source and observer; (c) a proper choice of a method for inverting the sensitivity matrix. While the prerequisite (a) is quite naturally fulfilled by considering the SR resonance characteristics (modal frequencies, intensities, and quality factors), the compliance with prerequisites (b) and (c) has benefitted greatly from earlier seminal work on geophysical inversion by T.R. Madden. Since it has been found that the electrodynamic non-uniformities of the Earth-ionosphere waveguide, primarily the day/night, play an essential role in low-frequency propagation, use has been made of theory for the two-dimensional telegraph equation (TDTE; Kirillov, 2002) developed on the basis of the innovative suggestion by Madden and Thompson (1965) to consider the waveguide, both physically and mathematically, by analogy with a two-dimensional transmission line. Because of the iterative nature of the inversion procedure and the complicated, non-analytical character of the propagation theory, a special, fast-running TDTE

  11. Tunable surface plasmon resonance and enhanced electrical conductivity of In doped ZnO colloidal nanocrystals.

    PubMed

    Ghosh, Sirshendu; Saha, Manas; De, S K

    2014-06-21

    We report a new synthesis process of colloidal indium (In) doped zinc oxide (ZIO) nanocrystals by a hot injection technique. By fine tuning the synthesis we reached the same nucleation temperature for indium oxide and zinc oxide which helped us to study a dopant precursor dependent In incorporation into the ZnO matrix by using different In sources. The dopant induced shape evolution changes the hexagonal pyramid structured ZnO to a platelet like structure upon 8% In doping. The introduction of trivalent In(3+) into the ZnO lattice and consequent substitution of divalent Zn(2+) generates free electrons in the conduction band which produces a plasmonic resonance in the infrared region. The electron concentration controls plasmon frequency as well as the band gap of host ZnO. The variation of the band gap and the modification of the conduction band have been explained by the Burstein-Moss effect and Mie's theory respectively. The In dopant changes the defect chemistry of pure ZnO nanocrystals which has been studied by photoluminescence and other spectroscopic measurements. The nanocrystals are highly stable in the organic medium and can be deposited as a crack free thin film on different substrates. Careful ligand exchange and thermal annealing of the spin cast film lead to a good conductive film (720 Ω per square to 120 Ω per square) with stable inherent plasmonic absorption in the infrared and 90% transmittance in the visible region. A temperature induced metal-semiconductor transition was found for doped ZnO nanocrystals. The transition temperature shifts to a lower temperature with increase of the doping concentration. PMID:24842309

  12. Noise analysis in fast magnetic resonance electrical impedance tomography (MREIT) based on spoiled multi gradient echo (SPMGE) pulse sequence

    NASA Astrophysics Data System (ADS)

    In Oh, Tong; Jeong, Woo Chul; Kim, Ji Eun; Sajib, Saurav Z. K.; Kim, Hyung Joong; In Kwon, Oh; Woo, Eung Je

    2014-08-01

    Magnetic resonance electrical impedance tomography (MREIT) is a promising non-invasive method to visualize a static cross-sectional conductivity and/or current density image by injecting low frequency currents. MREIT measures one component of the magnetic flux density caused by the injected current using a magnetic resonance (MR) scanner. For practical in vivo implementations of MREIT, especially for soft biological tissues where the MR signal rapidly decays, it is crucial to develop a technique for optimizing the magnetic flux density signal by the injected current while maintaining spatial-resolution and contrast. We design an MREIT pulse sequence by applying a spoiled multi-gradient-echo pulse sequence (SPMGE) to the injected current nonlinear encoding (ICNE), which fully injects the current at the end of the read-out gradient. The applied ICNE-SPMGE pulse sequence maximizes the duration of injected current almost up to a repetition time by measuring multiple magnetic flux density data. We analyze the noise level of measured magnetic flux density with respect to the pulse width of injection current and T_{2}^{*} relaxation time. In due consideration of the ICNE-SPMGE pulse sequence, using a reference information of T_{2}^{*} values in a local region of interest by a short pre-scan data, we predict the noise level of magnetic flux density to be measured for arbitrary repetition time TR. Results from phantom experiment demonstrate that the proposed method can predict the noise level of magnetic flux density for an appropriate TR = 40 ms using a reference scan for TR = 75 ms. The predicted noise level was compared with the noise level of directly measured magnetic flux density data.

  13. Functional Magnetic Resonance Imaging of Electrical and Optogenetic Deep Brain Stimulation at the Rat Nucleus Accumbens.

    PubMed

    Albaugh, Daniel L; Salzwedel, Andrew; Van Den Berge, Nathalie; Gao, Wei; Stuber, Garret D; Shih, Yen-Yu Ian

    2016-01-01

    Deep brain stimulation of the nucleus accumbens (NAc-DBS) is an emerging therapy for diverse, refractory neuropsychiatric diseases. Although DBS therapy is broadly hypothesized to work through large-scale neural modulation, little is known regarding the neural circuits and networks affected by NAc-DBS. Using a healthy, sedated rat model of NAc-DBS, we employed both evoked- and functional connectivity (fc) MRI to examine the functional circuit and network changes achieved by electrical NAc stimulation. Optogenetic-fMRI experiments were also undertaken to evaluate the circuit modulation profile achieved by selective stimulation of NAc neurons. NAc-DBS directly modulated neural activity within prefrontal cortex and a large number of subcortical limbic areas (e.g., amygdala, lateral hypothalamus), and influenced functional connectivity among sensorimotor, executive, and limbic networks. The pattern and extent of circuit modulation measured by evoked-fMRI was relatively insensitive to DBS frequency. Optogenetic stimulation of NAc cell bodies induced a positive fMRI signal in the NAc, but no other detectable downstream responses, indicating that therapeutic NAc-DBS might exert its effect through antidromic stimulation. Our study provides a comprehensive mapping of circuit and network-level neuromodulation by NAc-DBS, which should facilitate our developing understanding of its therapeutic mechanisms of action. PMID:27601003

  14. Simulations and phantom evaluations of magnetic resonance electrical impedance tomography (MREIT) for breast cancer detection

    NASA Astrophysics Data System (ADS)

    Sadleir, Rosalind J.; Sajib, Saurav Z. K.; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

    2013-05-01

    MREIT is a new imaging modality that can be used to reconstruct high-resolution conductivity images of the human body. Since conductivity values of cancerous tissues in the breast are significantly higher than those of surrounding normal tissues, breast imaging using MREIT may provide a new noninvasive way of detecting early stage of cancer. In this paper, we present results of experimental and numerical simulation studies of breast MREIT. We built a realistic three-dimensional model of the human breast connected to a simplified model of the chest including the heart and evaluated the ability of MREIT to detect cancerous anomalies in a background material with similar electrical properties to breast tissue. We performed numerical simulations of various scenarios in breast MREIT including assessment of the effects of fat inclusions and effects related to noise levels, such as changing the amplitude of injected currents, effect of added noise and number of averages. Phantom results showed straightforward detection of cancerous anomalies in a background was possible with low currents and few averages. The simulation results showed it should be possible to detect a cancerous anomaly in the breast, while restricting the maximal current density in the heart below published levels for nerve excitation.

  15. Functional Magnetic Resonance Imaging of Electrical and Optogenetic Deep Brain Stimulation at the Rat Nucleus Accumbens

    PubMed Central

    Albaugh, Daniel L.; Salzwedel, Andrew; Van Den Berge, Nathalie; Gao, Wei; Stuber, Garret D.; Shih, Yen-Yu Ian

    2016-01-01

    Deep brain stimulation of the nucleus accumbens (NAc-DBS) is an emerging therapy for diverse, refractory neuropsychiatric diseases. Although DBS therapy is broadly hypothesized to work through large-scale neural modulation, little is known regarding the neural circuits and networks affected by NAc-DBS. Using a healthy, sedated rat model of NAc-DBS, we employed both evoked- and functional connectivity (fc) MRI to examine the functional circuit and network changes achieved by electrical NAc stimulation. Optogenetic-fMRI experiments were also undertaken to evaluate the circuit modulation profile achieved by selective stimulation of NAc neurons. NAc-DBS directly modulated neural activity within prefrontal cortex and a large number of subcortical limbic areas (e.g., amygdala, lateral hypothalamus), and influenced functional connectivity among sensorimotor, executive, and limbic networks. The pattern and extent of circuit modulation measured by evoked-fMRI was relatively insensitive to DBS frequency. Optogenetic stimulation of NAc cell bodies induced a positive fMRI signal in the NAc, but no other detectable downstream responses, indicating that therapeutic NAc-DBS might exert its effect through antidromic stimulation. Our study provides a comprehensive mapping of circuit and network-level neuromodulation by NAc-DBS, which should facilitate our developing understanding of its therapeutic mechanisms of action. PMID:27601003

  16. Magnetic resonance electrical impedance tomography (MREIT) based on the solution of the convection equation using FEM with stabilization.

    PubMed

    Oran, Omer Faruk; Ider, Yusuf Ziya

    2012-08-21

    Most algorithms for magnetic resonance electrical impedance tomography (MREIT) concentrate on reconstructing the internal conductivity distribution of a conductive object from the Laplacian of only one component of the magnetic flux density (∇²B(z)) generated by the internal current distribution. In this study, a new algorithm is proposed to solve this ∇²B(z)-based MREIT problem which is mathematically formulated as the steady-state scalar pure convection equation. Numerical methods developed for the solution of the more general convection-diffusion equation are utilized. It is known that the solution of the pure convection equation is numerically unstable if sharp variations of the field variable (in this case conductivity) exist or if there are inconsistent boundary conditions. Various stabilization techniques, based on introducing artificial diffusion, are developed to handle such cases and in this study the streamline upwind Petrov-Galerkin (SUPG) stabilization method is incorporated into the Galerkin weighted residual finite element method (FEM) to numerically solve the MREIT problem. The proposed algorithm is tested with simulated and also experimental data from phantoms. Successful conductivity reconstructions are obtained by solving the related convection equation using the Galerkin weighted residual FEM when there are no sharp variations in the actual conductivity distribution. However, when there is noise in the magnetic flux density data or when there are sharp variations in conductivity, it is found that SUPG stabilization is beneficial. PMID:22837046

  17. Electron spin resonance and electrical transport in films of poly (3,4-ethylenedioxythiophene) doped with poly(styrenesulphonate)

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Keun; You, Seunghun; Jeon, Sunam; Ryu, Na-Hyun; Park, Ki Hun; Myung-Hoon, Kim; Kim, Dong Hun; Kim, Sun Hee; Schiff, Eric A.

    2015-07-01

    We report electron spin resonance (ESR) and electrical transport measurements in pristine poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulphonate) (PEDOT:PSS) films and ethylene glycol (EG)-treated PEDOT:PSS films. Based on the assumption that ESR from PEDOT:PSS is mainly due to hole polarons, we estimated the polaron mobility in the PEDOT:PSS films as μ p ≈ 0.1 - 1 cm2 V-1 s-1. We also estimated that bipolaron mobilities are in the range of approximately 10-100 cm2 V-1 s-1, assuming that the initial hole density is unaffected by bipolaron formation. We measured transient currents following application of voltage bias in several films, which had the features of space-charge limited currents despite being measured with coplanar electrodes. The relative nominal mobilities obtained for hole polarons in PEDOT:PSS and for bipolarons in EG-PEDOT:PSS were not inconsistent with the results obtained from the ESR and conductivity measurements. However, although the inferred mobility was voltage-independent for untreated samples with hole polarons, the inferred mobility increased steeply with the applied voltage, consistent with exp ( √{ V } ) behavior, for EG-treated samples.

  18. Recombination centers in 4H-SiC investigated by electrically detected magnetic resonance and ab initio modeling

    NASA Astrophysics Data System (ADS)

    Cottom, J.; Gruber, G.; Hadley, P.; Koch, M.; Pobegen, G.; Aichinger, T.; Shluger, A.

    2016-05-01

    Electrically detected magnetic resonance (EDMR) is a powerful technique for the observation and categorization of paramagnetic defects within semiconductors. The interpretation of the recorded EDMR spectra has long proved to be challenging. Here, defect spectra are identified by comparing EDMR measurements with extensive ab initio calculations. The defect identification is based upon the defect symmetry and the form of the hyperfine (HF) structure. A full description is given of how an accurate spectrum can be generated from the theoretical data by considering some thousand individual HF contributions out of some billion possibilities. This approach is illustrated with a defect observed in nitrogen implanted silicon carbide (SiC). Nitrogen implantation is a high energy process that gives rise to a high defect concentration. The majority of these defects are removed during the dopant activation anneal, shifting the interstitial nitrogen to the desired substitutional lattice sites, where they act as shallow donors. EDMR shows that a deep-level defect persists after the dopant activation anneal. This defect is characterized as having a g c ∥ B = 2.0054 ( 4 ) and g c ⊥ B = 2.0006 ( 4 ) , with pronounced hyperfine shoulder peaks with a 13 G peak to peak separation. The nitrogen at a carbon site next to a silicon vacancy ( N C V Si ) center is identified as the persistent deep-level defect responsible for the observed EDMR signal and the associated dopant deactivation.

  19. Optical switching of nematic liquid crystal film arising from induced electric field of localized surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Quint, Makiko T.; Delgado, Silverio; Paredes, John H.; Hirst, Linda S.; Ghosh, Sayantani

    2015-08-01

    We have developed an all-optical method to control the in- and out-of-plane spatial orientation of nematic liquid crystal (NLC) molecules by leveraging the highly localized electric fields produced in the near-field regime of gold nanoparticle (AuNP) layers. A 1-2 micron thick NLC film is deposited on a close-packed drop-cast AuNP layer, excited with tunable optical sources and the transmission of white light through it analyzed using polarization optics as a function of incident light wavelength, excitation power and sample temperature. Our findings, supported by simulations using discrete-dipole approximations, establish the optical switching effect to be repeatable, reversible, spectrally-selective, operational over a broad temperature range, including room temperature, and requiring very small on-resonance excitation intensity (0.3 W/cm2). For the case of the in-plane switching we have additionally demonstrated that controlling the incident excitation polarization can continuously vary the alignment of the NLC molecules, allowing for grayscale transmission.

  20. Use of 3-D magnetic resonance electrical impedance tomography in detecting human cerebral stroke: a simulation study*

    PubMed Central

    Gao, Nuo; Zhu, Shan-an; He, Bin

    2005-01-01

    We have developed a new three dimensional (3-D) conductivity imaging approach and have used it to detect human brain conductivity changes corresponding to acute cerebral stroke. The proposed Magnetic Resonance Electrical Impedance Tomography (MREIT) approach is based on the J-Substitution algorithm and is expanded to imaging 3-D subject conductivity distribution changes. Computer simulation studies have been conducted to evaluate the present MREIT imaging approach. Simulations of both types of cerebral stroke, hemorrhagic stroke and ischemic stroke, were performed on a four-sphere head model. Simulation results showed that the correlation coefficient (CC) and relative error (RE) between target and estimated conductivity distributions were 0.9245±0.0068 and 8.9997%±0.0084%, for hemorrhagic stroke, and 0.6748±0.0197 and 8.8986%±0.0089%, for ischemic stroke, when the SNR (signal-to-noise radio) of added GWN (Gaussian White Noise) was 40. The convergence characteristic was also evaluated according to the changes of CC and RE with different iteration numbers. The CC increases and RE decreases monotonously with the increasing number of iterations. The present simulation results show the feasibility of the proposed 3-D MREIT approach in hemorrhagic and ischemic stroke detection and suggest that the method may become a useful alternative in clinical diagnosis of acute cerebral stroke in humans. PMID:15822161

  1. Electrically small, near-field resonant parasitic (NFRP) antennas augmented with passive and active circuit elements to enhance their functionality

    NASA Astrophysics Data System (ADS)

    Zhu, Ning

    Metamaterials have drawn considerable attention because they can exhibit epsilon-negative (ENG) and/or mu-negative (MNG) properties, which in turn can lead to exotic physical effects that can enable interesting, practical applications. For instance, ENG and MNG properties can be engineered to yield double negative (DNG) properties, such as a negative index of refraction, which leads to flat lenses. Similarly, their extreme versions enable cloaking effects. Inspired by such metamaterial properties, a promising methodology has been developed to design electrically small antennas (ESAs). These ESAs use unit cells of metamaterials as their near-field resonant parasitic (NFRP) elements. This new metamaterial-inspired antenna miniaturization method is extended in this dissertation by augmenting the antenna designs with circuits. A rectifying circuit augmentation is used to achieve electrically small, high efficiency rectenna systems. Rectennas are the enabling components of power harvesting and wireless power transmission systems. Electrically small, integrated rectennas have become popular and in demand for several wireless applications including sensor networks and bio-implanted devices. Four global positioning system (GPS) L1 frequency (1.5754 GHz) rectenna systems were designed, fabricated and measured: three resistor-loaded and one supercapacitor-loaded. The simulated and measured results will be described; good agreement between them was obtained. The NFRP ESAs are also augmented with active, non-Foster elements in order to overcome the physical limits of the impedance bandwidth of passive ESA systems. Unlike conventional active external matching network approaches, the non-Foster components are incorporated directly into the NFRP element of the ESA. Three 300 MHz non-Foster circuit-augmented broadband, ESA systems were demonstrated: an Egyptian axe monopole (EAM) antenna, an Egyptian axe dipole (EAD) antenna, and a protractor antenna. The simulated and measured

  2. Electrical and ionic conductivity effects on magic-angle spinning nuclear magnetic resonance parameters of CuI

    NASA Astrophysics Data System (ADS)

    Yesinowski, James P.; Ladouceur, Harold D.; Purdy, Andrew P.; Miller, Joel B.

    2010-12-01

    We investigate experimentally and theoretically the effects of two different types of conductivity, electrical and ionic, upon magic-angle spinning NMR spectra. The experimental demonstration of these effects involves 63Cu, 65Cu, and 127I variable temperature MAS-NMR experiments on samples of γ-CuI, a Cu+-ion conductor at elevated temperatures as well as a wide bandgap semiconductor. We extend previous observations that the chemical shifts depend very strongly upon the square of the spinning-speed as well as the particular sample studied and the magnetic field strength. By using the 207Pb resonance of lead nitrate mixed with the γ-CuI as an internal chemical shift thermometer we show that frictional heating effects of the rotor do not account for the observations. Instead, we find that spinning bulk CuI, a p-type semiconductor due to Cu+ vacancies in nonstoichiometric samples, in a magnetic field generates induced AC electric currents from the Lorentz force that can resistively heat the sample by over 200 °C. These induced currents oscillate along the rotor spinning axis at the spinning speed. Their associated heating effects are disrupted in samples containing inert filler material, indicating the existence of macroscopic current pathways between micron-sized crystallites. Accurate measurements of the temperature-dependence of the 63Cu and 127I chemical shifts in such diluted samples reveal that they are of similar magnitude (ca. 0.27 ppm/K) but opposite sign (being negative for 63Cu), and appear to depend slightly upon the particular sample. This relationship is identical to the corresponding slopes of the chemical shifts versus square of the spinning speed, again consistent with sample heating as the source of the observed large shift changes. Higher drive-gas pressures are required to spin samples that have higher effective electrical conductivities, indicating the presence of a braking effect arising from the induced currents produced by rotating a

  3. Electrical and ionic conductivity effects on magic-angle spinning nuclear magnetic resonance parameters of CuI.

    PubMed

    Yesinowski, James P; Ladouceur, Harold D; Purdy, Andrew P; Miller, Joel B

    2010-12-21

    We investigate experimentally and theoretically the effects of two different types of conductivity, electrical and ionic, upon magic-angle spinning NMR spectra. The experimental demonstration of these effects involves (63)Cu, (65)Cu, and (127)I variable temperature MAS-NMR experiments on samples of γ-CuI, a Cu(+)-ion conductor at elevated temperatures as well as a wide bandgap semiconductor. We extend previous observations that the chemical shifts depend very strongly upon the square of the spinning-speed as well as the particular sample studied and the magnetic field strength. By using the (207)Pb resonance of lead nitrate mixed with the γ-CuI as an internal chemical shift thermometer we show that frictional heating effects of the rotor do not account for the observations. Instead, we find that spinning bulk CuI, a p-type semiconductor due to Cu(+) vacancies in nonstoichiometric samples, in a magnetic field generates induced AC electric currents from the Lorentz force that can resistively heat the sample by over 200 °C. These induced currents oscillate along the rotor spinning axis at the spinning speed. Their associated heating effects are disrupted in samples containing inert filler material, indicating the existence of macroscopic current pathways between micron-sized crystallites. Accurate measurements of the temperature-dependence of the (63)Cu and (127)I chemical shifts in such diluted samples reveal that they are of similar magnitude (ca. 0.27 ppm/K) but opposite sign (being negative for (63)Cu), and appear to depend slightly upon the particular sample. This relationship is identical to the corresponding slopes of the chemical shifts versus square of the spinning speed, again consistent with sample heating as the source of the observed large shift changes. Higher drive-gas pressures are required to spin samples that have higher effective electrical conductivities, indicating the presence of a braking effect arising from the induced currents produced by

  4. An electrically detected magnetic resonance study of performance limiting defects in SiC metal oxide semiconductor field effect transistors

    NASA Astrophysics Data System (ADS)

    Cochrane, C. J.; Lenahan, P. M.; Lelis, A. J.

    2011-01-01

    In this study, we utilize electrically detected magnetic resonance (EDMR) techniques and electrical measurements to study defects in SiC based metal oxide semiconductor field effect transistors (MOSFETs). We compare results on a series of SiC MOSFETs prepared with significantly different processing parameters. The EDMR is detected through spin dependent recombination (SDR) in most cases. However, in some devices at a fairly high negative bias, the EDMR likely also involves spin dependent trap-assisted tunneling (SDT) between defects on both sides of the SiC/SiO2 interface. At least three different defects have been detected in the magnetic resonance measurements. The defects observed include two at the SiC/SiO2 interface or on the SiC side of the SiC/SiO2 interface: one is very likely a vacancy center with a distribution which extends into the bulk of the SiC and the other is likely a "dangling bond" defect. A third defect, located on the SiO2 side of the SiC/SiO2 interface, has a spectrum very similar to that previously reported for an oxygen deficient silicon coupled to a hydrogen atom. In nearly all cases, we observe a strong dominating single line EDMR spectrum with an isotropic g≈2.0027. In some samples, this strong central line is accompanied by two pairs of considerably weaker side peaks which we link to hyperfine interactions with nearby Si and C atoms. The pattern is physically reasonable for a silicon vacancy in SiC. We therefore tentatively assign it to a silicon vacancy or silicon vacancy associated defect in the SiC. In one set of devices with very high interface trap density we observe another dominating spectrum with g∥=2.0026 and g⊥=2.0010 with the symmetry axis coincident with the [0001] and nearly the SiC/SiO2 interface normal. We ascribe this EDMR spectrum to a "dangling bond" defect. A third EDMR spectrum shows up in some devices at a fairly large negative gate bias. The phase of this spectrum is quite consistently opposite to that of the

  5. Abnormal T2-STIR Magnetic Resonance in Hypertrophic Cardiomyopathy: A Marker of Advanced Disease and Electrical Myocardial Instability

    PubMed Central

    Pisciella, Lorena; Barison, Andrea; Del Franco, Annamaria; Zachara, Elisabetta; Piaggi, Paolo; Re, Federica; Pingitore, Alessandro; Emdin, Michele; Lombardi, Massimo

    2014-01-01

    Background Myocardial hyperintensity on T2-weighted short-tau inversion recovery (STIR) (HyT2) cardiac magnetic resonance (CMR) images has been demonstrated in patients with hypertrophic cardiomyopathy (HCM) and is considered a sign of acute damage. The aim of the current study was to evaluate the relationship between HyT2 and both a) markers of ventricular electrical instability and b) clinical and CMR parameters. Methods Sixty-five patients underwent a thorough clinical examination, consisting of 24-h ECG recording and CMR examination including functional evaluation, T2-STIR images and late gadolinium enhancement (LGE). Results HyT2 was detected in 27 patients (42%), and subjects with HyT2 showed a greater left ventricle (LV) mass index (p<0.001), lower LV ejection fraction (p = 0.05) and greater extent of LGE (p<0.001) compared to those without HyT2. Twenty-two subjects (34%) presented non-sustained ventricular tachycardia (NSVT) on the 24-h ECG recording, 21 (95%) of whom exhibited HyT2. Based on the logistic regression analysis, HyT2 (odds ratio [OR]: 165, 95% CI 11–2455, p<0.001) and LGE extent (1.1, 1.0–1.3, p<0.001) served as independent predictors of NSVT, while the presence of LGE was not associated with NSVT occurrence (p = 0.49). The presence of HyT2 was associated with lower heart rate variability (p = 0.006) and a higher number of arrhythmic risk factors (p<0.001). Conclusions In HCM patients, HyT2 upon CMR examination is associated with more advanced disease and increased arrhythmic burden. PMID:25356653

  6. Anomalous solute transport in saturated porous media: Relating transport model parameters to electrical and nuclear magnetic resonance properties

    NASA Astrophysics Data System (ADS)

    Swanson, Ryan D.; Binley, Andrew; Keating, Kristina; France, Samantha; Osterman, Gordon; Day-Lewis, Frederick D.; Singha, Kamini

    2015-02-01

    The advection-dispersion equation (ADE) fails to describe commonly observed non-Fickian solute transport in saturated porous media, necessitating the use of other models such as the dual-domain mass-transfer (DDMT) model. DDMT model parameters are commonly calibrated via curve fitting, providing little insight into the relation between effective parameters and physical properties of the medium. There is a clear need for material characterization techniques that can provide insight into the geometry and connectedness of pore spaces related to transport model parameters. Here, we consider proton nuclear magnetic resonance (NMR), direct-current (DC) resistivity, and complex conductivity (CC) measurements for this purpose, and assess these methods using glass beads as a control and two different samples of the zeolite clinoptilolite, a material that demonstrates non-Fickian transport due to intragranular porosity. We estimate DDMT parameters via calibration of a transport model to column-scale solute tracer tests, and compare NMR, DC resistivity, CC results, which reveal that grain size alone does not control transport properties and measured geophysical parameters; rather, volume and arrangement of the pore space play important roles. NMR cannot provide estimates of more-mobile and less-mobile pore volumes in the absence of tracer tests because these estimates depend critically on the selection of a material-dependent and flow-dependent cutoff time. Increased electrical connectedness from DC resistivity measurements are associated with greater mobile pore space determined from transport model calibration. CC was hypothesized to be related to length scales of mass transfer, but the CC response is unrelated to DDMT.

  7. Response of the /sup 1/P/sup 0/ resonance near n = 3 in the H/sup -/ continuum to external electric fields

    SciTech Connect

    Cohen, S.

    1986-05-01

    The response to external electric fields of the /sup 1/P/sup 0/ resonance in the H/sup -/ photodetachment continuum below the n = 3 hydrogenic excitation threshold is investigated. Using the relativistic (..beta.. = 0.806) 650 MeV H/sup -/ beam at the Clinton P. Anderson Meson Physics Facility (LAMPF) in Los Alamos, the fourth harmonic (2.66 nm) of a Nd:YAG laser is Doppler shifted to provide a continuously tunable photon beam in the rest frame of the ions. The magnetic field from pulsed Helmholtz coils, surrounding the photon-H/sup -/ interaction point provides a Lorentz-transformed barycentric electric field. Relative total photodetachment cross sections were measured as a function of photon energy and electric field. The resulting spectra were fit to a Fano line shape. 70 refs., 28 figs., 7 tabs.

  8. A High-Q Resonant Pressure Microsensor with Through-Glass Electrical Interconnections Based on Wafer-Level MEMS Vacuum Packaging

    PubMed Central

    Luo, Zhenyu; Chen, Deyong; Wang, Junbo; Li, Yinan; Chen, Jian

    2014-01-01

    This paper presents a high-Q resonant pressure microsensor with through-glass electrical interconnections based on wafer-level MEMS vacuum packaging. An approach to maintaining high-vacuum conditions by integrating the MEMS fabrication process with getter material preparation is presented in this paper. In this device, the pressure under measurement causes a deflection of a pressure-sensitive silicon square diaphragm, which is further translated to stress build up in “H” type doubly-clamped micro resonant beams, leading to a resonance frequency shift. The device geometries were optimized using FEM simulation and a 4-inch SOI wafer was used for device fabrication, which required only three photolithographic steps. In the device fabrication, a non-evaporable metal thin film as the getter material was sputtered on a Pyrex 7740 glass wafer, which was then anodically bonded to the patterned SOI wafer for vacuum packaging. Through-glass via holes predefined in the glass wafer functioned as the electrical interconnections between the patterned SOI wafer and the surrounding electrical components. Experimental results recorded that the Q-factor of the resonant beam was beyond 22,000, with a differential sensitivity of 89.86 Hz/kPa, a device resolution of 10 Pa and a nonlinearity of 0.02% F.S with the pressure varying from 50 kPa to 100 kPa. In addition, the temperature drift coefficient was less than −0.01% F.S/°C in the range of −40 °C to 70 °C, the long-term stability error was quantified as 0.01% F.S over a 5-month period and the accuracy of the microsensor was better than 0.01% F.S. PMID:25521385

  9. Comparison of electrical velocimetry and cardiac magnetic resonance imaging for the non-invasive determination of cardiac output.

    PubMed

    Trinkmann, Frederik; Berger, Manuel; Doesch, Christina; Papavassiliu, Theano; Schoenberg, Stefan O; Borggrefe, Martin; Kaden, Jens J; Saur, Joachim

    2016-08-01

    A novel algorithm of impedance cardiography referred to as electrical velocimetry (EV) has been introduced for non-invasive determination of cardiac output (CO). Previous validation studies yielded diverging results and no comparison with the non-invasive gold standard cardiac magnetic resonance imaging (CMR) has been performed. We therefore aimed to prospectively assess the accuracy and reproducibility of EV compared to CMR. 152 consecutive stable patients undergoing CMR were enrolled. EV measurements were taken twice before or after CMR in supine position and averaged over 20 s (AESCULON(®), Osypka Medical, Berlin, Germany). Bland-Altman analysis showed insufficient agreement of EV and CMR with a mean bias of 1.2 ± 1.4 l/min (bias 23 ± 26 %, percentage error 51 %). Reproducibility was high with 0.0 ± 0.3 l/min (bias 0 ± 8 %, percentage error 15 %). Outlier analysis revealed gender, height, CO and stroke volume (SV) by CMR as independent predictors for larger variation. Stratification of COCMR in quintiles demonstrated a good agreement for low values (<4.4 l/min) with bias increasing significantly with quintile as high as 3.1 ± 1.1 l/min (p < 0.001). Reproducibility was not affected (p = 0.71). Subgroup analysis in patients with arrhythmias (p = 0.19), changes in thoracic fluid content (p = 0.51) or left heart failure (p = 0.47) could not detect significant differences in accuracy. EV showed insufficient agreement with CMR and good reproducibility. Gender, height and increasing CO and SV were associated with increased bias while not affecting reproducibility. Therefore, absolute values should not be used interchangeably in clinical routine. EV yet may find its place for clinical application with further investigation on its trending ability pending. PMID:26115774

  10. Magneto-electric interactions at bending resonance in an asymmetric multiferroic composite: Theory and experiment on the influence of electrode position

    NASA Astrophysics Data System (ADS)

    Sreenivasulu, G.; Qu, P.; Petrov, V. M.; Qu, Hongwei; Srinivasan, G.

    2015-05-01

    In magnetostrictive-piezoelectric bilayers the strength of mechanical strain mediated magneto-electric (ME) interactions shows a resonance enhancement at bending modes. Such composites when operating under frequency modulation at bending resonance have very high ME sensitivity and are of importance for ultrasensitive magnetometers. This report provides an avenue for further enhancement in the ME sensitivity by strategic positioning of the electrodes in the bilayer. We discuss the theory and measurements on the dependence of ME coupling on the position of electrodes in a lead zirconate titanate-permendur bilayer. Samples of effective length L with full electrodes and partial electrodes of length l = L/3 are studied. A five-fold increase in ME voltage coefficient (MEVC) at bending resonance and a 75% increase in low-frequency MEVC are measured as the partial electrode position is moved from the free-end to clamped-end of the bilayer. When the partial electrode is close to the clamped end, the low-frequency and resonance MEVC are 22% and 45% higher, respectively, than for fully electroded bilayer. According to the model discussed here these observations could be attributed to non-uniform stress along the sample length under flexural deformation. Such deformations are stronger at the free-end than at the clamped-end, thereby reducing the stress produced by applied magnetic fields and a reduction in MEVC. Estimates of MEVC are in good agreement with the data.

  11. Giant electric field control of magnetism and narrow ferromagnetic resonance linewidth in FeCoSiB/Si/SiO2/PMN-PT multiferroic heterostructures

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Wang, X.; Xie, L.; Hu, Z.; Lin, H.; Zhou, Z.; Nan, T.; Yang, X.; Howe, B. M.; Jones, J. G.; Brown, G. J.; Sun, N. X.

    2016-06-01

    It has been challenging to achieve combined strong magnetoelectric coupling and narrow ferromagnetic resonance (FMR) linewidth in multiferroic heterostructures. Electric field induced large effective field of 175 Oe and narrow FMR linewidth of 40 Oe were observed in FeCoSiB/Si/SiO2/PMN-PT heterostructures with substrate clamping effect minimized through removing the Si substrate. As a comparison, FeCoSiB/PMN-PT heterostructures with FeCoSiB film directly deposited on PMN-PT showed a comparable voltage induced effective magnetic field but a significantly larger FMR linewidth of 283 Oe. These multiferroic heterostructures exhibiting combined giant magnetoelectric coupling and narrow ferromagnetic resonance linewidth offer great opportunities for integrated voltage tunable RF magnetic devices.

  12. Electron heating enhancement due to plasma series resonance in a capacitively coupled RF discharge: Electrical modeling and comparison to experimental measurements

    NASA Astrophysics Data System (ADS)

    Cao, Minglu; Lu, Yijia; Cheng, Jia; Ji, Linhong

    2016-09-01

    The electron heating enhancement due to the self-excitation of the plasma series resonance in capacitively coupled plasmas is revisited by a combination of an equivalent circuit model and experiments. To improve the model accuracy, measured voltage waveforms at the powered electrode are used instead of prescribing a sinusoidal voltage supply in series with a bias capacitance. The results calculated from the electrical model are consistent with the experimental measurements performed by a Langmuir probe with verification of a microwave interferometer, at pressures of 0.2 and 0.3 Torr. High harmonics occurring in the discharge currents agree with observations in previous research. The nonlinear plasma series resonance effect is found to have a notable contribution to both ohmic and stochastic heating evaluated by the electron heating efficiencies.

  13. Electrically detected double electron-electron resonance: exchange interaction of ?P donors and P? defects at the Si/SiO? interface

    NASA Astrophysics Data System (ADS)

    Suckert, Max; Hoehne, Felix; Dreher, Lukas; Kuenzl, Markus; Huebl, Hans; Stutzmann, Martin; Brandt, Martin S.

    2013-10-01

    We study the coupling of P? dangling bond defects at the Si/SiO2 interface and 31P donors in an epitaxial layer directly underneath using electrically detected double electron-electron resonance (EDDEER). An exponential decay of the EDDEER signal is observed, which is attributed to a broad distribution of exchange coupling strengths J/2π from 25 kHz to 3 MHz. Comparison of the experimental data with a numerical simulation of the exchange coupling shows that this range of coupling strengths corresponds to 31P-P? distances ranging from 14 nm to 20 nm.

  14. Coupled optical and electrical study of thin-film InGaAs photodetector integrated with surface InP Mie resonators

    NASA Astrophysics Data System (ADS)

    Fu, Dong; Liu, Jietao; Song, Jiakun; Yu, Hailong; Zhang, Zuyin; Wang, Wenbo; Xu, Yun; Song, Guofeng; Wei, Xin

    2016-03-01

    High-index dielectric and semiconductor nanostructures with characteristics of low absorption loss and artificially controlled scattering properties have grasped an increasing attention for improving the performance of thin-film photovoltaic devices. In this work, combined optical and electrical simulations were performed for thin-film InP/In0.53Ga0.47As/InP hetero-junction photodetector with periodically arranged InP nano-cylinders in the in-coupling configuration. It is found that the carefully designed InP nano-cylinders possess strongly substrate-coupled Mie resonances and can effectively couple incident light into the guided mode, both of which significantly increase optical absorption. Further study from the electrical aspects shows that enhancement of external quantum efficiency is as high as 82% and 83% in the configurations with the optimized nano-cylinders and the optimized period, respectively. Moreover, we demonstrate that the integration of InP nano-cylinders does not degrade the electrical performance, since the surface recombination is effectively suppressed by separating the absorber layer where carriers generate and the air/semiconductor interface. The comprehensive modeling including optical and electrical perspectives provides a more practical description for device performance than the optical-only simulation and is expected to advance the design of thin-film absorber layer based optoelectronic devices for fast response and high efficiency.

  15. Combined electrical and resonant optical excitation characterization of multi-quantum well InGaN-based light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Presa, S.; Maaskant, P. P.; Kappers, M. J.; Humphreys, C. J.; Corbett, B.

    2016-07-01

    We present a comprehensive study of the emission spectra and electrical characteristics of InGaN/GaN multi-quantum well light-emitting diode (LED) structures under resonant optical pumping and varying electrical bias. A 5 quantum well LED with a thin well (1.5 nm) and a relatively thick barrier (6.6 nm) shows strong bias-dependent properties in the emission spectra, poor photovoltaic carrier escape under forward bias and an increase in effective resistance when compared with a 10 quantum well LED with a thin (4 nm) barrier. These properties are due to a strong piezoelectric field in the well and associated reduced field in the thicker barrier. We compare the voltage ideality factors for the LEDs under electrical injection, light emission with current, photovoltaic mode (PV) and photoluminescence (PL) emission. The PV and PL methods provide similar values for the ideality which are lower than for the resistance-limited electrical method. Under optical pumping the presence of an n-type InGaN underlayer in a commercial LED sample is shown to act as a second photovoltaic source reducing the photovoltage and the extracted ideality factor to less than 1. The use of photovoltaic measurements together with bias-dependent spectrally resolved luminescence is a powerful method to provide valuable insights into the dynamics of GaN LEDs.

  16. An Overview of Thunderstorm-Related Research on the Atmospheric Electric Field, Schumann Resonances, Sprites, and the Ionosphere at Sopron, Hungary

    NASA Astrophysics Data System (ADS)

    Sátori, Gabriella; Rycroft, Michael; Bencze, Pál; Märcz, Ferenc; Bór, József; Barta, Veronika; Nagy, Tamás; Kovács, Károly

    2013-05-01

    This paper gives a resume of the papers written in English which (a) describe some of the recording instruments in use at the Nagycenk Observatory (NCK) since the International Geophysical Year (IGY 1957-1958) and up to the present time, (b) summarise the most important and different types of observations associated with thunderstorms which have been made there, and (c) discuss their various geophysical interpretations. The paper describes the main results which have been obtained in four areas of thunderstorm associated atmospheric and geospace science within the context of Earth system science. These relate to the following parameters of atmospheric electricity: the vertical electric potential gradient just above the Earth's surface and the air-Earth current as well as the point discharge current, Schumann resonance (SR) signals of the Earth-ionosphere cavity at 8, 14 and 20 Hz, transient luminous events (TLEs), and some aspects of the behaviour of the ionosphere. Deductions from these data sets are concerned with the global lightning activity and the conductivity of the air, with diurnal, seasonal, annual and long-term variations of the SR amplitudes and resonant frequencies in terms of migrating thunderstorm centres, with transient SR excitations and with sprites and other TLEs, and with ionospheric disturbances. The paper closes with some thoughts on future research directions based on the observations at NCK and Sopron and the results achieved since the IGY.

  17. Innovative Free-range Resonant Electrical Energy Delivery system (FREE-D System) for a ventricular assist device using wireless power.

    PubMed

    Waters, Benjamin H; Smith, Joshua R; Bonde, Pramod

    2014-01-01

    Technological innovation of a smaller, single moving part has an advantage over earlier large pulsatile ventricular assist devices (VADs) prone to mechanical failure. Drivelines limit the potential for extended patient survival durations with newer pumps and act as source for infection, increased morbidity, rehospitalizations, and reduced quality of life. The Free-range Resonant Electrical Energy Delivery (FREE-D) wireless power system uses magnetically coupled resonators to efficiently transfer power. We demonstrate the efficiency over distance of this system. The experimental setup consists of an radiofrequency amplifier and control board which drives the transmit resonator coil, and a receiver unit consisting of a resonant coil attached to a radiofrequency rectifier and power management module. The power management module supplies power to the axial pump, which was set at 9,600 rpm. To achieve a seamless wireless delivery in any room size, we introduced a third relay coil. This relay coil can be installed throughout a room, whereas a single relay coil could be built into a jacket worn by the patient, which would always be within range of the receive coil implanted in the patient's body. The power was delivered over a meter distance without interruptions or fluctuations with coil, rectifier, and regulator efficiency more than 80% and overall system efficiency of 61%. The axial pump worked well throughout the 8 hours of continuous operation. Having same setup on the opposite side can double the distance. A tether-free operation of a VAD can be achieved by FREE-D system in room-size distances. It has the potential to make the VAD therapy more acceptable from the patient perspective. PMID:24299972

  18. Influence of surface plasmon resonances of silver nanoparticles on optical and electrical properties of textured silicon solar cell

    SciTech Connect

    Sardana, Sanjay K.; Chava, Venkata S. N.; Thouti, Eshwar; Chander, Nikhil; Komarala, Vamsi K.; Kumar, Sanjai; Reddy, S. R.

    2014-02-17

    Here, we report average reflectance reduction of ∼8% in wavelength range of 300–1100 nm after coupling surface plasmon resonances (SPRs) of silver nanoparticles (NPs) to textured silicon (T-Si) surface. The enhancement of photocurrent from T-Si solar cell in off-resonant SPR region observed due to better radiative efficiency of NPs leading to outflow of scattered far-field into silicon maximized power generating electrons. Improvement in series resistance, fill factor, and open-circuit voltage (insensitive NPs size and morphology) are also observed with NPs along with photocurrent enhancement (sensitive to NPs sizes), which resulted cell efficiency enhancement from 4.49% to 6.42% for large area of 12.24 cm{sup 2}.

  19. Influence of surface plasmon resonances of silver nanoparticles on optical and electrical properties of textured silicon solar cell

    NASA Astrophysics Data System (ADS)

    Sardana, Sanjay K.; Chava, Venkata S. N.; Thouti, Eshwar; Chander, Nikhil; Kumar, Sanjai; Reddy, S. R.; Komarala, Vamsi K.

    2014-02-01

    Here, we report average reflectance reduction of ˜8% in wavelength range of 300-1100 nm after coupling surface plasmon resonances (SPRs) of silver nanoparticles (NPs) to textured silicon (T-Si) surface. The enhancement of photocurrent from T-Si solar cell in off-resonant SPR region observed due to better radiative efficiency of NPs leading to outflow of scattered far-field into silicon maximized power generating electrons. Improvement in series resistance, fill factor, and open-circuit voltage (insensitive NPs size and morphology) are also observed with NPs along with photocurrent enhancement (sensitive to NPs sizes), which resulted cell efficiency enhancement from 4.49% to 6.42% for large area of 12.24 cm2.

  20. Control of Ferromagnetic Resonance Frequency and Frequency Linewidth by Electrical Fields in FeCo/[Pb(Mg1/3Nb2/3)O3]0.68-[PbTiO3]0.32(011) Heterostructures

    NASA Astrophysics Data System (ADS)

    Phuoc, Nguyen N.; Ong, C. K.

    2016-06-01

    We report our detailed investigation of the electrical tuning of the ferromagnetic resonance frequency and frequency linewidth in multiferroic heterostructures consisting of FeCo thin films grown onto [Pb(Mg1/3Nb2/3) O3]0.68-[PbTiO3]0.32 (PMN-PT) substrates with NiFe underlayers. Our study shows that the electrical tuning range of both ferromagnetic resonance frequency and frequency linewidth in this FeCo/PMN-PT heterostructure can be very large. Specifically, the resonance frequency can be tuned from 1.8 GHz to 10.3 GHz, and the frequency linewidth can be changed from 1.6 GHz to 7.3 GHz. The electrical tuning of these microwave properties is discussed in conjunction with the result from the static magnetic characterization and is explained based on the strain-driven magnetoelectric heterostructured effect.

  1. Gradient-based Electrical Properties Tomography (gEPT): a Robust Method for Mapping Electrical Properties of Biological Tissues In Vivo Using Magnetic Resonance Imaging

    PubMed Central

    Liu, Jiaen; Zhang, Xiaotong; Schmitter, Sebastian; Van de Moortele, Pierre-Francois; He, Bin

    2014-01-01

    Purpose To develop high-resolution electrical properties tomography (EPT) methods and investigate a gradient-based EPT (gEPT) approach which aims to reconstruct the electrical properties (EP), including conductivity and permittivity, of an imaged sample from experimentally measured B1 maps with improved boundary reconstruction and robustness against measurement noise. Theory and Methods Using a multi-channel transmit/receive stripline head coil, with acquired B1 maps for each coil element, by assuming negligible Bz component compared to transverse B1 components, a theory describing the relationship between B1 field, EP value and their spatial gradient has been proposed. The final EP images were obtained through spatial integration over the reconstructed EP gradient. Numerical simulation, physical phantom and in vivo human experiments at 7 T have been conducted to evaluate the performance of the proposed methods. Results Reconstruction results were compared with target EP values in both simulations and phantom experiments. Human experimental results were compared with EP values in literature. Satisfactory agreement was observed with improved boundary reconstruction. Importantly, the proposed gEPT method proved to be more robust against noise when compared to previously described non-gradient-based EPT approaches. Conclusion The proposed gEPT approach holds promises to improve EP mapping quality by recovering the boundary information and enhancing robustness against noise. PMID:25213371

  2. Dependence of electrically detected magnetic resonance signal shape from iron-contaminated silicon wafers on the thermal treatment of the samples

    NASA Astrophysics Data System (ADS)

    Mchedlidze, T.; Matsumoto, K.; Lin, T.-C.; Suezawa, M.

    1999-12-01

    The shape of the electrically detected magnetic resonance (EDMR) signal from iron-contaminated Czochralski-grown silicon (CZ-Si) samples strongly depends on the thermal treatments applied to the samples before and after the contamination procedure, although the average g-value of the spectra apparently does not vary. A signal from an iron-contaminated float-zone grown silicon (FZ-Si) sample was detected employing an EDMR signal detection unit with enhanced sensitivity. For similar contamination levels, the signal from the FZ-Si sample has amplitude about {1}/{45} that of the CZ-Si signal and has specific shape. Further study of the EDMR signals from iron-contaminated Si samples will be useful for the investigation of gettering and recombination processes in Si wafers. Besides that, dependence of the EDMR spectrum shape on the thermal processes employed can help to pinpoint the process responsible for wafer contamination during semiconductor device fabrication.

  3. Theory of X-ray absorption and resonant X-ray emission spectra by electric quadrupole excitation in light rare-earth systems

    NASA Astrophysics Data System (ADS)

    Nakazawa, M.; Fukui, K.; Kotani, A.

    2003-02-01

    We have made precise theoretical calculations for both 2 p3/2→4 f X-ray absorption spectroscopy (XAS) and 4 d→2 p3/2 resonant X-ray emission spectroscopy (RXES) by electric quadrupole excitations at the L3 edge of light rare-earth elements, by means of atomic model with full multiplet effects. The calculation is based on the second-order optical formula, and the effect of the incident photon polarization is taken into account. It is shown that the 4 d-4 f interaction plays a more important role in 4 d→2 p3/2 RXES than the 4 f-4 f interaction does. Moreover, the calculated results of 4 d→2 p3/2 RXES show the strong polarization dependence, and it is originated from the spin multiplicity, which is derived from the 4 d-4 f interaction, of the RXES final states.

  4. Nonresonant and resonant cloaking of an electrically large dielectric spherical object by a multilayer isotropic metamaterial cover.

    PubMed

    Abouelsaood, Ahmed; Afifi, Islam; Eshrah, Islam

    2015-07-20

    Mie theory and genetic algorithms are used to determine the parameters and performance of cloaks made of homogeneous isotropic metamaterials that would hide a spherical dielectric object of size comparable to the incident radiation wavelength. A single-layer (SL) cover with negative permittivity and permeability can produce a much greater reduction in the extinction efficiency than one with the permittivity and permeability of positive or opposite signs. Minimization of the extinction efficiency in the former case leads to both nonresonant and resonant solutions. Adding a second layer to the cover can lead to a significant enhancement of the bandwidth, but only to a modest reduction in the extinction efficiency at the design wavelength. In the SL case, Debye's scattering series is used to show that the nonresonant and resonant minima of the extinction efficiency correspond to scattering phase shifts approximately equal to zero and -π, respectively, and to understand the simple approximate expressions for the cloak parameters of the nonresonant solutions. The series also explains the value of the outer radius of a multilayer cloak, provides a link to a previously studied isotropic approximation to a transformation optics cloak, and indicates that a cloak consisting of an odd number of alternate double-negative and double-positive layers will probably give the best possible performance. PMID:26367849

  5. Aqueous flat-cells perpendicular to the electric field for use in electron paramagnetic resonance spectroscopy, II: design.

    PubMed

    Sidabras, Jason W; Mett, Richard R; Hyde, James S

    2005-02-01

    This paper builds on the work of Mett and Hyde [J. Magn. Reson. 165 (2003) 137]. Various aqueous flat-cell geometries in the perpendicular orientation have been studied using Ansoft High Frequency Structure Simulator (version 9.0, Pittsburgh, PA) and Computer Simulation Technology Microwave Studio (version 5.0, Wellesley Hills, MA). The analytic theory of Mett and Hyde has been refined to predict optimum dimensions of multiple sample cell structures including the effect of the sample holder dielectric properties and the interaction of the cells with each other on EPR signal strength. From these calculations and simulations we propose a practical multiple cell sample structure for use in commercial rectangular TE102 cavities that yields 2.0-2.3 times higher sensitivity relative to a single flat-cell in the nodal orientation. We also describe a modified TE102 resonator design with square rather than cylindrical sample-access stacks that is predicted to give a factor of 2.2-2.7 enhancement in EPR signal strength of a single flat-cell in the nodal orientation. These signal enhancements are predicted with sample holders fabricated from polytetrafluoroethylene. Additional improvement in EPR signal of up to 75% can be achieved by using sample holder materials with lower dielectric constants. PMID:15649761

  6. Characterization of PMN-PT piezoelectric single crystal and PMN-PT 1-3 composite at elevated temperatures by electrical impedance resonance analysis.

    PubMed

    Wu, Zhengbin; Xi, Kui

    2014-07-01

    In this paper, lead magnesium niobate-lead titanate (PMN-PT) piezoelectric single crystal and its 1-3 composite counterpart were characterized and analyzed under different stable temperatures using both a Simulated Annealing (SA) optimization algorithm and the commercial software PRAP (Piezoelectric Resonance Analysis Program). Electrical impedance resonance characteristics of the two material samples over the range 25-125 °C were measured. The correlation between experimental data and numerical fits derived from both SA and PRAP is considered. Calculation of the determination coefficient (R1(2)) between numerically fitted and measured results is above 95% for both methods. Furthermore, variations in the number of data values used for the fit introduced no more than 3.1% uncertainty on the calculated material parameters. It is found that the complex material parameters of PMN-PT composite are more dependent on temperature than the single crystal. The phase transition of the PMN-PT, which is close to 90 °C, has an effect on the high temperature material characteristics of both piezoelectric materials. These calculated complex material parameters can be used for the design of ultrasonic transducers for elevated temperature applications. PMID:24495996

  7. Using nitrogen-14 nuclear quadrupole resonance and electric field gradient information for the study of radiation effects

    SciTech Connect

    Iselin, L.H.

    1995-12-01

    Nitrogen-14 nuclear quadrupole resonance (NQR) was used in an attempt to detect the effects of ionizing radiation on organic material. Previously reported resonances for urea were detected at 2,913.32 {+-} 0.01 kHz and 2,347.88 {+-} 0.08 kHz with associated T{sub 2}* values 780 {+-} 20 {micro}s and 523 {+-} 24 {micro}s, respectively. The previously unreported {nu}{sub {minus}} line for urea-d{sup 4} was detected at 2,381 {+-} 0.04 Khz and used to determine accurately for the first time the values for the nuclear quadrupole coupling constant {chi} (3,548.74 {+-} 0.03 kHz) and the asymmetry parameter {eta} (0.31571 {+-} 0.00007) for urea-d{sup 4}. The inverse linewidth parameter T{sub 2}* for {nu}{sub +} was measured at 928 {+-} 23 {micro}s and for {nu}{sub {minus}} at 721 {+-} 12 {micro}s. Townes and Dailey analysis was performed and urea-d{sup 4} exhibits a 0.004 increase in lone pair electronic density and a slight decrease in N-H bond electronic density, as compared to urea, probably due to the mass difference. A relationship is proposed, referred to as NQR linewidth analysis, between the dynamic spin relaxation times T{sub 2} and T{sub 2}* and the widths of the distributions of the NQR parameters. Linewidth analysis is presented as a tool for possible use in future NQR work in all area, not just radiation effects. This relationship is tested using sodium nitrite T{sub 2} and T{sub 2}* values for {nu}{sub {minus}} and {nu}{sub {minus}} as a function of temperature.

  8. Observation of the 5 p3 /2→6 p3 /2 electric-dipole-forbidden transition in atomic rubidium using optical-optical double-resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Ponciano-Ojeda, F.; Hernández-Gómez, S.; López-Hernández, O.; Mojica-Casique, C.; Colín-Rodríguez, R.; Ramírez-Martínez, F.; Flores-Mijangos, J.; Sahagún, D.; Jáuregui, R.; Jiménez-Mier, J.

    2015-10-01

    Direct evidence of excitation of the 5 p3 /2→6 p3 /2 electric-dipole-forbidden transition in atomic rubidium is presented. The experiments were performed in a room-temperature rubidium cell with continuous-wave external cavity diode lasers. Optical-optical double-resonance spectroscopy with counterpropagating beams allows the detection of the nondipole transition free of Doppler broadening. The 5 p3 /2 state is prepared by excitation with a laser locked to the maximum F cyclic transition of the D2 line, and the forbidden transition is produced by excitation with a 911 nm laser. Production of the forbidden transition is monitored by detection of the 420 nm fluorescence that results from decay of the 6 p3 /2 state. Spectra with three narrow lines (≈13 MHz FWHM) with the characteristic F -1 , F , and F +1 splitting of the 6 p3 /2 hyperfine structure in both rubidium isotopes were obtained. The results are in very good agreement with a direct calculation that takes into account the 5 s →5 p3 /2 preparation dynamics, the 5 p3 /2→6 p3 /2 nondipole excitation geometry, and the 6 p3 /2→5 s1 /2 decay. The comparison also shows that the electric-dipole-forbidden transition is a very sensitive probe of the preparation dynamics.

  9. Quantitative analysis of the reconstruction errors of the currently popular algorithm of magnetic resonance electrical property tomography at the interfaces of adjacent tissues.

    PubMed

    Duan, Song; Xu, Chao; Deng, Guanhua; Wang, Jiajia; Liu, Feng; Xin, Sherman Xuegang

    2016-06-01

    This work quantitatively analyzed the reconstruction errors (REs) of electrical property (EP) images using a currently popular algorithm of magnetic resonance electrical property tomography (MREPT), which occurred along the tissue interfaces. Transmitted magnetic fields B1+ were acquired at 3 T using a birdcage coil loaded with a phantom consisting of various adjacent tissues. Homogeneous Helmholtz was employed to calculate the EP maps by Laplacian computation of central differences. The maps of absolute REs (aREs) and relative REs (rREs) were calculated. The maximum and mean rREs, in addition to rRE distributions at the interfaces, were presented. Reconstructed EP maps showed various REs along different interface boundaries. Among all the investigated tissue interfaces, the kidney-fat interface presented the maximum mean rREs for both conductivity and relative permittivity. The minimum mean rRE of conductivity was observed at the spleen-muscle interface, and the minimum mean rRE of relative permittivity was detected along the lung-heart interface. The mean rREs ranged from 0.3986 to 36.11 for conductivity and 0.2218 to 11.96 for relative permittivity. Overall, this research indicates that different REs occur at various tissue boundaries, as shown by the currently popular algorithm of MREPT. Thus, REs should be considered when applying MREPT to reconstruct the EP distributions inside the human body. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27037715

  10. Acupuncture-Related Modulation of Pain-Associated Brain Networks During Electrical Pain Stimulation: A Functional Magnetic Resonance Imaging Study

    PubMed Central

    Choi, Kyung-Eun; Gizewski, Elke R.; Wen, Ming; Rampp, Thomas; Gasser, Thomas; Dobos, Gustav J.; Forsting, Michael; Musial, Frauke

    2014-01-01

    Abstract Objective: Findings of existing functional MRI (fMRI) studies on the neural mechanisms that mediate effects of acupuncture analgesia are inconsistent. This study analyzes the effects of manual acupuncture on pain ratings and brain activation in response to experimental, electrical pain stimuli. Design: Fourteen healthy volunteers were examined by using a 1.5-T MRI scanner. The intensity of pain stimuli was adjusted to individual pain ratings on a numeric rating scale. Baseline fMRI was performed during electrical pain stimulation in a blocked design. For the second session, manual acupuncture with repeated stimulation was performed on contralateral acupoints—large intestine 4, liver 3, and stomach 36—before imaging. After imaging, subjective pain ratings and ratings of the de qi sensation were assessed. Results: Compared with baseline, volunteers showed modulated brain activity under pain conditions in the cingulate gyrus, insula, primary somatosensory cortex, and prefrontal areas after the acupuncture session. In accordance with the literature, anterior insular and prefrontal activity seemed to be correlated with acupuncture treatment. Conclusion: This study supports the existence of analgesic acupuncture effects that outlast the needling period. Pain-associated brain areas were modulated in direct response to a preceding acupuncture treatment. PMID:25389905

  11. Anomalous Solute Transport in Saturated Porous Media: Linking Transport Model Parameters to Electrical and Nuclear Magnetic Resonance Properties

    NASA Astrophysics Data System (ADS)

    Swanson, R. D.; Binley, A. M.; Keating, K.; France, S.; Osterman, G. K.; Day-Lewis, F. D.; Singha, K.

    2013-12-01

    The advection-dispersion equation fails to describe non-Fickian solute transport in saturated porous media, necessitating the use of other models. The dual-domain mass transfer (DDMT) model partitions the total porosity into mobile and less-mobile domains with solute exchange between the domains; consequently, the DDMT model can produce a better fit to breakthrough curves (BTCs) in systems defined by more- and less-mobile components. However, direct experimental estimation of DDMT model parameters such as rate of exchange and the mobile and less-mobile porosities remains elusive. Consequently, model parameters are often calculated purely as a model fitting exercise. There is a clear need for material characterization techniques that can offer some insight into the pore space geometrical arrangement, particularly if such techniques can be extended to the field scale. Here, we interpret static direct-current (DC) resistivity, complex resistivity (CR) and nuclear magnetic resonance (NMR) geophysical measurements in the characterization of mass transfer parameters. We use two different samples of the zeolite clinoptilolite, a material shown to demonstrate solute mass transfer due to a significant intragranular porosity, along with glass beads as a control. We explore the relation between geophysical and DDMT parameters in conjunction with supporting material characterization methods. Our results reveal how these geophysical measurements can offer some insight into the pore structures controlling the observed anomalous transport behavior.

  12. Modeling of resonant magneto-electric effect in a magnetostrictive and piezoelectric laminate composite structure coupled by a bonding material

    NASA Astrophysics Data System (ADS)

    Hasanyan, D.; Wang, Y.; Gao, J.; Li, M.; Shen, Y.; Li, J.; Viehland, D.

    2012-09-01

    The harmonic magneto-electro-elastic vibration of a thin laminated composite was considered. A theoretical model, including shear lag and vibration effects was developed for predicting the magneto-electric (ME) effect in a laminate composite consisting of magnetostrictive and piezoelectric layers. To avoid bending, we assumed that the composite was geometrically symmetric. For finite length symmetrically fabricated laminates, we derived the dynamic strain-stress field and ME coefficients, including shear lag and vibration effects for several boundary conditions. Parametric studies are presented to evaluate the influences of material properties and geometries on the strain distribution and the ME coefficient. Analytical expressions indicate that the shear lag and the vibration frequency strongly influence the strain distribution in the laminates and these effects strongly influence the ME coefficients.

  13. Electrical surface-resistivity, dielectric resonance, polarization and magnetic properties of Bi0.5Sr0.5FeO3-δ thin films grown by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Balamurugan, K.; Ramachandran, B.; Krishna Surendra, M.; Kumar, N. Harish; Ramachandra Rao, M. S.; Santhosh, P. N.

    2014-09-01

    Polycrystalline and highly preferred (1\\,0\\,\\bar{{2}}) orientated Bi0.5Sr0.5FeO3-δ thin films were grown by pulsed laser deposition (PLD) on n-Si (2 0 0) and MgO (2 0 0) single crystalline substrates respectively. The thin films were inspected using x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy and atomic force microscopy techniques. The electrical surface-resistivity, dielectric resonance, electric polarization, and magnetic properties of the thin films were studied. At room temperature, depending on deposition conditions, the polycrystalline thin films grown on n-Si substrates were found to exhibit an electrical surface-resistivity of the order of 103-106 Ω, a piezoelectric resonance in the frequency range of about 25-26 MHz, a relaxor-type ferroelectric hysteresis with a maximum polarization of 0.015-0.055 µC cm-2 and magnetic hysteresis. Similarly, the thin films grown on MgO substrates exhibited an electrical surface-resistivity of the order of 109 Ω, multiple piezoelectric resonances in the frequency range of about 8-45 MHz, a linear variation of polarization with applied electric field and either a linearly varying magnetization or magnetic hysteresis which depends on the deposition conditions.

  14. Functional magnetic resonance imaging of the rat cerebellum during electrical stimulation of the fore- and hindpaw at 7 T

    NASA Astrophysics Data System (ADS)

    Peeters, Ronald; Verhoye, Marleen; Vos, Bart; De Schutter, Erik; Van der Linden, Anne-Marie

    1999-05-01

    Blood oxygenation level dependent contrast (BOLD) functional MRI responses at 7T were observed in the cerebellum of alpha- chloralose anesthetized rats in response to innocuous electrical stimulation of a forepaw or hindpaw. The responses were imaged in both coronal and sagittal slices which allowed for a clear delineation and localization of the observed activations. We demonstrate the validity of our fMRI protocol by imaging the responses in somatosensory cortex to the same stimuli and by showing a high level of reproducibility of the cerebellar responses. Widespread bilateral activations were found with mainly a patchy and medio-lateral band organization, more pronounced ipsilaterally. There was no overlap between the cerebellar activations caused by forepaw or hindpaw stimulation. Most remarkable was the overall horizontal organization of these responses: for both stimulation paradigms the patches and bands of activation were roughly positioned in either a cranial or caudal plane running antero-posteriorly through the whole cerebellum. This is the first fMRI study in the cerebellum of the rat. We relate our findings to the known projection patterns found with other techniques and to human fMRI studies. The horizontal organization found wasn't observed before in other studies using other techniques.

  15. Electric-dipole moment of CaF by molecular-beam, laser-rf, double-resonance study of Stark splittings

    SciTech Connect

    Childs, W.J.; Goodman, L.S.; Nielsen, U.; Pfeufer, V.

    1984-01-01

    The electronic structure of diatomic molecules is much more complex for open-shell sytems (radicals) than for the normal closed-shell systems, and the development of an adequate theoretical understanding will require a substantial upgrading of experimental knowledge in both quality and quantity. The alkaline-earth monohalide family of radicals, with only a single electron outside closed-shell cores, would appear to be a logical starting point for such studies, and there has been a great increase in work in this area in the last few years in spite of the special difficulties of working with free radicals. As the work of measuring the vibrational and rotational structure of the electronic states has become more complete, attention has turned to study of the much weaker spin-rotation and hyperfine interactions. Within the last three years, these interactions have been studied systematically at high precision in the calcium monohalide family with the molecular-beam, laser-rf double-resonance technique. The same method has now been modified and extended to make possible measurement of the electric-dipole moments of these molecules through observation of the Stark splittings of radiofrequency transitions. It is hoped that when considered together, the several types of data will make it possible to understand the ground-state electronic wave functions of these molecules at least qualitatively. 2 figures.

  16. Effect of a weak static magnetic field on nitrogen-14 quadrupole resonance in the case of an axially symmetric electric field gradient tensor.

    PubMed

    Guendouz, Laouès; Aissani, Sarra; Marêché, Jean-François; Retournard, Alain; Marande, Pierre-Louis; Canet, Daniel

    2013-01-01

    The application of a weak static B0 magnetic field (less than 1 mT) may produce a well-defined splitting of the (14)N Quadrupole Resonance line when the electric field gradient tensor at the nitrogen nucleus level is of axial symmetry. It is theoretically shown and experimentally confirmed that the actual splitting (when it exists) as well as the line-shape and the signal intensity depends on three factors: (i) the amplitude of B0, (ii) the amplitude and pulse duration of the radio-frequency field, B1, used for detecting the NQR signal, and (iii) the relative orientation of B0 and B1. For instance, when B0 is parallel to B1 and regardless of the B0 value, the signal intensity is three times larger than when B0 is perpendicular to B1. This point is of some importance in practice since NQR measurements are almost always performed in the earth field. Moreover, in the course of this study, it has been recognized that important pieces of information regarding line-shape are contained in data points at the beginning of the free induction decay (fid) which, in practice, are eliminated for avoiding spurious signals due to probe ringing. It has been found that these data points can generally be retrieved by linear prediction (LP) procedures. As a further LP benefit, the signal intensity loss (by about a factor of three) is regained. PMID:24183810

  17. Single-resonator double-negative metamaterial

    DOEpatents

    Warne, Larry K.; Basilio, Lorena I.; Langston, William L.; Johnson, William A.; Ihlefeld, Jon; Ginn, III, James C.; Clem, Paul G.; Sinclair, Michael B.

    2016-06-21

    Resonances can be tuned in dielectric resonators in order to construct single-resonator, negative-index metamaterials. For example, high-contrast inclusions in the form of metallic dipoles can be used to shift the first electric resonance down (in frequency) to the first magnetic resonance, or alternatively, air splits can be used to shift the first magnetic resonance up (in frequency) near the first electric resonance. Degenerate dielectric designs become especially useful in infrared- or visible-frequency applications where the resonator sizes associated with the lack of high-permittivity materials can become of sufficient size to enable propagation of higher-order lattice modes in the resulting medium.

  18. Resonances and resonance widths

    SciTech Connect

    Collins, T.

    1986-05-01

    Two-dimensional betatron resonances are much more important than their simple one-dimensional counterparts and exhibit a strong dependence on the betatron phase advance per cell. A practical definition of ''width'' is expanded upon in order to display these relations in tables. A primarily pedagogical introduction is given to explain the tables, and also to encourage a wider capability for deriving resonance behavior and wider use of ''designer'' resonances.

  19. ¹⁴N Quadrupole Resonance line broadening due to the earth magnetic field, occuring only in the case of an axially symmetric electric field gradient tensor.

    PubMed

    Aissani, Sarra; Guendouz, Laouès; Marande, Pierre-Louis; Canet, Daniel

    2015-01-01

    As demonstrated before, the application of a weak static B0 magnetic field (less than 10 G) may produce definite effects on the ¹⁴N Quadrupole Resonance line when the electric field gradient tensor at the nitrogen nucleus level is of axial symmetry. Here, we address more precisely the problem of the relative orientation of the two magnetic fields (the static field and the radio-frequency field of the pure NQR experiment). For a field of 6G, the evolution of the signal intensity, as a function of this relative orientation, is in very good agreement with the theoretical predictions. There is in particular an intensity loss by a factor of three when going from the parallel configuration to the perpendicular configuration. By contrast, when dealing with a very weak magnetic field (as the earth field, around 0.5 G), this effect drops to ca. 1.5 in the case Hexamethylenetetramine (HMT).This is explained by the fact that the Zeeman shift (due to the very weak magnetic field) becomes comparable to the natural line-width. The latter can therefore be determined by accounting for this competition. Still in the case of HMT, the estimated natural line-width is half the observed line-width. The extra broadening is thus attributed to earth magnetic field. The latter constitutes therefore the main cause of the difference between the natural transverse relaxation time (T₂) and the transverse relaxation time derived from the observed line-width (T₂(⁎)). PMID:25910551

  20. Evaluation and optimization of quartz resonant-frequency retuned fork force sensors with high Q factors, and the associated electric circuits, for non-contact atomic force microscopy.

    PubMed

    Ooe, Hiroaki; Fujii, Mikihiro; Tomitori, Masahiko; Arai, Toyoko

    2016-02-01

    High-Q factor retuned fork (RTF) force sensors made from quartz tuning forks, and the electric circuits for the sensors, were evaluated and optimized to improve the performance of non-contact atomic force microscopy (nc-AFM) performed under ultrahigh vacuum (UHV) conditions. To exploit the high Q factor of the RTF sensor, the oscillation of the RTF sensor was excited at its resonant frequency, using a stray capacitance compensation circuit to cancel the excitation signal leaked through the stray capacitor of the sensor. To improve the signal-to-noise (S/N) ratio in the detected signal, a small capacitor was inserted before the input of an operational (OP) amplifier placed in an UHV chamber, which reduced the output noise from the amplifier. A low-noise, wideband OP amplifier produced a superior S/N ratio, compared with a precision OP amplifier. The thermal vibrational density spectra of the RTF sensors were evaluated using the circuit. The RTF sensor with an effective spring constant value as low as 1000 N/m provided a lower minimum detection limit for force differentiation. A nc-AFM image of a Si(111)-7 × 7 surface was produced with atomic resolution using the RTF sensor in a constant frequency shift mode; tunneling current and energy dissipation images with atomic resolution were also simultaneously produced. The high-Q factor RTF sensor showed potential for the high sensitivity of energy dissipation as small as 1 meV/cycle and the high-resolution analysis of non-conservative force interactions. PMID:26931855

  1. Evaluation and optimization of quartz resonant-frequency retuned fork force sensors with high Q factors, and the associated electric circuits, for non-contact atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Ooe, Hiroaki; Fujii, Mikihiro; Tomitori, Masahiko; Arai, Toyoko

    2016-02-01

    High-Q factor retuned fork (RTF) force sensors made from quartz tuning forks, and the electric circuits for the sensors, were evaluated and optimized to improve the performance of non-contact atomic force microscopy (nc-AFM) performed under ultrahigh vacuum (UHV) conditions. To exploit the high Q factor of the RTF sensor, the oscillation of the RTF sensor was excited at its resonant frequency, using a stray capacitance compensation circuit to cancel the excitation signal leaked through the stray capacitor of the sensor. To improve the signal-to-noise (S/N) ratio in the detected signal, a small capacitor was inserted before the input of an operational (OP) amplifier placed in an UHV chamber, which reduced the output noise from the amplifier. A low-noise, wideband OP amplifier produced a superior S/N ratio, compared with a precision OP amplifier. The thermal vibrational density spectra of the RTF sensors were evaluated using the circuit. The RTF sensor with an effective spring constant value as low as 1000 N/m provided a lower minimum detection limit for force differentiation. A nc-AFM image of a Si(111)-7 × 7 surface was produced with atomic resolution using the RTF sensor in a constant frequency shift mode; tunneling current and energy dissipation images with atomic resolution were also simultaneously produced. The high-Q factor RTF sensor showed potential for the high sensitivity of energy dissipation as small as 1 meV/cycle and the high-resolution analysis of non-conservative force interactions.

  2. Combined electrical resistivity tomography and magnetic resonance sounding investigation of the surface-water/groundwater interaction in the Urema Graben, Mozambique

    NASA Astrophysics Data System (ADS)

    Chirindja, F. J.; Dahlin, T.; Perttu, N.; Steinbruch, F.; Owen, R.

    2016-05-01

    This study focusses on the hydrogeology of Urema Graben, especially possible interactions between surface water and groundwater around Lake Urema, in Gorongosa National Park (GNP). Lake Urema is the only permanent water source for wildlife inside GNP, and there are concerns that it will disappear due to interferences in surface-water/groundwater interactions as a result of changes in the hydraulic environment. As the lake is the only permanent water source, this would be a disaster for the ecosystem of the park. The sub-surface geology in Urema Graben was investigated by 20 km of electrical resistivity tomography (ERT) and three magnetic resonance sounding (MRS) surveys. The average depth penetration was 60 and 100 m, respectively. The location of the ERT lines was decided based on general rift morphology and therefore orientated perpendicular to Urema Graben, from the transitional areas of the margins of the Barue platform in the west to the Cheringoma plateau escarpments in the east. ERT and MRS both indicate a second aquifer, where Urema Lake is a window of the first upper semi-confined aquifer, while the lower aquifer is confined by a clay layer 30-40 m thick. The location and depth of this aquifer suggest that it is probably linked to the Pungwe River which could be a main source of recharge during the dry season. If a dam or any other infra-structure is constructed in Pungwe River upstream of GNP, the groundwater level will decrease which could lead to drying out of Urema Lake.

  3. Measurement on electrical tunability of microstrip line resonators using YBa2Cu3O7-δ/SrTiO3/MgO multilayer thin films

    NASA Astrophysics Data System (ADS)

    Han, Seok K.; Kim, Jeha; Lee, Sang Yeol; Kang, Kwang-Yong

    1995-09-01

    We have fabricated YBa2Cu3O7-(delta ) (YBCO) superconducting line resonator and tunable line resonator on ferroelectric Sr0.5Ba0.5TiO3 (SBTO) buffered MgO(100) substrate and discussed the frequency shift mechanism of superconductor as a function of temperature and bias voltage, respectively. The resonators were designed using superconducting YBCO epitaxial thin films. Optimized resonator shown the resonant frequency of 10 GHz at 77 K. The YBCO films were grown in situ by pulsed laser deposition technique at 750 degree(s)C and oxygen partial pressure of 200 mTorr. The resonators have linear microstrip line separated by a gap of 5 micrometers and 0.5 mm, respectively. A gap is intentionally introduced to generate mainly a capacitive series reactance. The equivalence circuit of line resonator is a II network consisted of three capacitances. As the series capacitance C12 of SBTO ferroelectric thin films was changed by a bias voltage applied on the strip conductors including the gap, resonance frequency was shifted about 20 MHz from the unbiased center frequency of 10 GHz. The variation of resonance peak could be explained by a serial capacitance model. To find a central frequency mechanism depending on temperature, we fit the raw data using f(T)/f(10 K) and simple power law model. The shifting of the resonant frequencies due to temperature was fit to a two-fluid model, BCS theory and empirical formula. Also the surface impedance of superconducting YBCO films as a function of temperature at 10 GHz has been estimated by a transmission line method.

  4. Wavelength-tunable optical ring resonators

    DOEpatents

    Watts, Michael R.; Trotter, Douglas C.; Young, Ralph W.; Nielson, Gregory N.

    2009-11-10

    Optical ring resonator devices are disclosed that can be used for optical filtering, modulation or switching, or for use as photodetectors or sensors. These devices can be formed as microdisk ring resonators, or as open-ring resonators with an optical waveguide having a width that varies adiabatically. Electrical and mechanical connections to the open-ring resonators are made near a maximum width of the optical waveguide to minimize losses and thereby provide a high resonator Q. The ring resonators can be tuned using an integral electrical heater, or an integral semiconductor junction.

  5. Wavelength-tunable optical ring resonators

    DOEpatents

    Watts, Michael R.; Trotter, Douglas C.; Young, Ralph W.; Nielson, Gregory N.

    2011-07-19

    Optical ring resonator devices are disclosed that can be used for optical filtering, modulation or switching, or for use as photodetectors or sensors. These devices can be formed as microdisk ring resonators, or as open-ring resonators with an optical waveguide having a width that varies adiabatically. Electrical and mechanical connections to the open-ring resonators are made near a maximum width of the optical waveguide to minimize losses and thereby provide a high resonator Q. The ring resonators can be tuned using an integral electrical heater, or an integral semiconductor junction.

  6. A study on prevention of an electric discharge at an extraction electrode of an electron cyclotron resonance ion source for cancer therapy

    SciTech Connect

    Kishii, Y. Kawasaki, S.; Kitagawa, A.; Muramatsu, M.; Uchida, T.

    2014-02-15

    A compact ECR ion source has utilized for carbon radiotherapy. In order to increase beam intensity with higher electric field at the extraction electrode and be better ion supply stability for long periods, electric geometry and surface conditions of an extraction electrode have been studied. Focusing attention on black deposited substances on the extraction electrode, which were observed around the extraction electrode after long-term use, the relation between black deposited substances and the electrical insulation property is investigated. The black deposited substances were inspected for the thickness of deposit, surface roughness, structural arrangement examined using Raman spectroscopy, and characteristics of electric discharge in a test bench, which was set up to simulate the ECR ion source.

  7. Measurement of the internal stress and electric field in a resonating piezoelectric transformer for high-voltage applications using the electro-optic and photoelastic effects

    SciTech Connect

    VanGordon, James A.; Kovaleski, Scott D. Norgard, Peter; Gall, Brady B.; Dale, Gregory E.

    2014-02-15

    The high output voltages from piezoelectric transformers are currently being used to accelerate charged particle beams for x-ray and neutron production. Traditional methods of characterizing piezoelectric transformers (PTs) using electrical probes can decrease the voltage transformation ratio of the device due to the introduction of load impedances on the order of hundreds of kiloohms to hundreds of megaohms. Consequently, an optical diagnostic was developed that used the photoelastic and electro-optic effects present in piezoelectric materials that are transparent to a given optical wavelength to determine the internal stress and electric field. The combined effects of the piezoelectric, photoelastic, and electro-optic effects result in a time-dependent change the refractive indices of the material and produce an artificially induced, time-dependent birefringence in the piezoelectric material. This induced time-dependent birefringence results in a change in the relative phase difference between the ordinary and extraordinary wave components of a helium-neon laser beam. The change in phase difference between the wave components was measured using a set of linear polarizers. The measured change in phase difference was used to calculate the stress and electric field based on the nonlinear optical properties, the piezoelectric constitutive equations, and the boundary conditions of the PT. Maximum stresses of approximately 10 MPa and electric fields of as high as 6 kV/cm were measured with the optical diagnostic. Measured results were compared to results from both a simple one-dimensional (1D) model of the piezoelectric transformer and a three-dimensional (3D) finite element model. Measured stresses and electric fields along the length of an operating length-extensional PT for two different electrical loads were within at least 50 % of 3D finite element simulated results. Additionally, the 3D finite element results were more accurate than the results from the 1D model

  8. Measurement of the internal stress and electric field in a resonating piezoelectric transformer for high-voltage applications using the electro-optic and photoelastic effects.

    PubMed

    VanGordon, James A; Kovaleski, Scott D; Norgard, Peter; Gall, Brady B; Dale, Gregory E

    2014-02-01

    The high output voltages from piezoelectric transformers are currently being used to accelerate charged particle beams for x-ray and neutron production. Traditional methods of characterizing piezoelectric transformers (PTs) using electrical probes can decrease the voltage transformation ratio of the device due to the introduction of load impedances on the order of hundreds of kiloohms to hundreds of megaohms. Consequently, an optical diagnostic was developed that used the photoelastic and electro-optic effects present in piezoelectric materials that are transparent to a given optical wavelength to determine the internal stress and electric field. The combined effects of the piezoelectric, photoelastic, and electro-optic effects result in a time-dependent change the refractive indices of the material and produce an artificially induced, time-dependent birefringence in the piezoelectric material. This induced time-dependent birefringence results in a change in the relative phase difference between the ordinary and extraordinary wave components of a helium-neon laser beam. The change in phase difference between the wave components was measured using a set of linear polarizers. The measured change in phase difference was used to calculate the stress and electric field based on the nonlinear optical properties, the piezoelectric constitutive equations, and the boundary conditions of the PT. Maximum stresses of approximately 10 MPa and electric fields of as high as 6 kV/cm were measured with the optical diagnostic. Measured results were compared to results from both a simple one-dimensional (1D) model of the piezoelectric transformer and a three-dimensional (3D) finite element model. Measured stresses and electric fields along the length of an operating length-extensional PT for two different electrical loads were within at least 50 % of 3D finite element simulated results. Additionally, the 3D finite element results were more accurate than the results from the 1D model

  9. On the resonances and polarizabilities of split ring resonators

    NASA Astrophysics Data System (ADS)

    García-García, J.; Martín, F.; Baena, J. D.; Marqués, R.; Jelinek, L.

    2005-08-01

    In this paper, the behavior at resonance of split ring resonators (SRRs) and other related topologies, such as the nonbianisotropic SRR and the broadside-coupled SRR, are studied. It is shown that these structures exhibit a fundamental resonant mode (the quasistatic resonance) and other higher-order modes which are related to dynamic processes. The excitation of these modes by means of a properly polarized time varying magnetic and/or electric fields is discussed on the basis of resonator symmetries. To verify the electromagnetic properties of these resonators, simulations based on resonance excitation by nonuniform and uniform external fields have been performed. Inspection of the currents at resonances, inferred from particle symmetries and full-wave electromagnetic simulations, allows us to predict the first-order dipolar moments induced at the different resonators and to develop a classification of the resonances based on this concept. The experimental data, obtained in SRR-loaded waveguides, are in agreement with the theory and point out the rich phenomenology associated with these planar resonant structures.

  10. Proposal of Novel Method to Measure Young’s Modulus of Materials Using Change in Motional Capacitance of the Electrical Equivalent Circuit of Quartz-Crystal Tuning-Fork Tactile Sensor at Resonance

    NASA Astrophysics Data System (ADS)

    Hideaki Itoh,; Naoki Hatakeyama,

    2010-07-01

    We propose a novel method to measure the Young’s modulus of materials using the change in motional capacitance of the electrical equivalent circuit of a quartz-crystal tuning-fork tactile sensor at resonance before and after the sensor’s base coming into contact with materials with different Young’s moduli, such as silicon rubbers and plastics. How to measure the Young’s modulus of materials using the change in motional capacitance is investigated experimentally and theoretically. By our calculation of motional capacitance and from contact experiments on silicon rubbers and plastics, we found that there was a possibility to measure the Young’s modulus of materials using the relationship between the change in motional capacitance and their Young’s modulus.

  11. Proposal of Novel Method to Measure Young's Modulus of Materials Using Change in Motional Capacitance of the Electrical Equivalent Circuit of Quartz-Crystal Tuning-Fork Tactile Sensor at Resonance

    NASA Astrophysics Data System (ADS)

    Itoh, Hideaki; Hatakeyama, Naoki

    2010-07-01

    We propose a novel method to measure the Young's modulus of materials using the change in motional capacitance of the electrical equivalent circuit of a quartz-crystal tuning-fork tactile sensor at resonance before and after the sensor's base coming into contact with materials with different Young's moduli, such as silicon rubbers and plastics. How to measure the Young's modulus of materials using the change in motional capacitance is investigated experimentally and theoretically. By our calculation of motional capacitance and from contact experiments on silicon rubbers and plastics, we found that there was a possibility to measure the Young's modulus of materials using the relationship between the change in motional capacitance and their Young's modulus.

  12. Structural and electrical transport properties of MOVPE-grown pseudomorphic AlAs/InGaAs/InAs resonant tunneling diodes on InP substrates

    NASA Astrophysics Data System (ADS)

    Sugiyama, Hiroki; Teranishi, Atsushi; Suzuki, Safumi; Asada, Masahiro

    2014-03-01

    We report metal-organic vapor-phase epitaxy (MOVPE) growth of pseudomorphic AlAs/InGaAs/InAs resonant tunneling diodes (RTDs) on InP substrates for the first time. X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) observations reveal that a uniform strained InAs subwell is coherently grown in the double-barrier (DB) structure. The AlAs/InGaAs/InAs RTDs exhibit excellent current-voltage characteristics with a high peak current density (JP) of around 2 × 105 A/cm2 and peak-to-valley ratio (PVR) of around 6. A comparison with control RTDs consisting of AlAs/In0.8Ga0.2As DB confirms the effectiveness of InAs subwell insertion for the improvement of PVR.

  13. Optical resonator

    NASA Technical Reports Server (NTRS)

    Taghavi-Larigani, Shervin (Inventor); Vanzyl, Jakob J. (Inventor); Yariv, Amnon (Inventor)

    2006-01-01

    The invention discloses a semi-ring Fabry-Perot (SRFP) optical resonator structure comprising a medium including an edge forming a reflective facet and a waveguide within the medium, the waveguide having opposing ends formed by the reflective facet. The performance of the SRFP resonator can be further enhanced by including a Mach-Zehnder interferometer in the waveguide on one side of the gain medium. The optical resonator can be employed in a variety of optical devices. Laser structures using at least one SRFP resonator are disclosed where the resonators are disposed on opposite sides of a gain medium. Other laser structures employing one or more resonators on one side of a gain region are also disclosed.

  14. Resonance scraping

    SciTech Connect

    Collins, T.

    1986-06-01

    Protons lost in a ring leave at a few preferred locations, determined by some non-linear property of the dipoles. This paper suggests taking control of lost protons by beating the magnets at their own game - by means of a designed resonance used as a beam scraper. It is a study of suitable resonances, including estimates of the required multipole element strengths. The appropriate resonances are two-dimensional. A large number of figures is included.

  15. (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

    NASA Astrophysics Data System (ADS)

    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.

  16. Tandem resonator reflectance modulator

    DOEpatents

    Fritz, Ian J.; Wendt, Joel R.

    1994-01-01

    A wide band optical modulator is grown on a substrate as tandem Fabry-Perot resonators including three mirrors spaced by two cavities. The absorption of one cavity is changed relative to the absorption of the other cavity by an applied electric field, to cause a change in total reflected light, as light reflecting from the outer mirrors is in phase and light reflecting from the inner mirror is out of phase with light from the outer mirrors.

  17. Tandem resonator reflectance modulator

    DOEpatents

    Fritz, I.J.; Wendt, J.R.

    1994-09-06

    A wide band optical modulator is grown on a substrate as tandem Fabry-Perot resonators including three mirrors spaced by two cavities. The absorption of one cavity is changed relative to the absorption of the other cavity by an applied electric field, to cause a change in total reflected light, as light reflecting from the outer mirrors is in phase and light reflecting from the inner mirror is out of phase with light from the outer mirrors. 8 figs.

  18. RESONATOR PARTICLE SEPARATOR

    DOEpatents

    Blewett, J.P.; Kiesling, J.D.

    1963-06-11

    A wave-guide resonator structure is designed for use in separating particles of equal momentum but differing in mass, having energies exceeding one billion eiectron volts. The particles referred to are those of sub-atomic size and are generally produced as a result of the bombardment of a target by a beam such as protons produced in a high energy accelerator. In the resonator a travelling electric wave is produced which travels at the same rate of speed as the unwanted particle which is thus deflected continuously over the length of the resonator. The wanted particle is slightly out of phase with the travelling wave so that over the whole length of the resonator it has a net deflection of substantially zero. The travelling wave is established in a wave guide of rectangular cross section in which stubs are provided to store magnetic wave energy leaving the electric wave energy in the main structure to obtain the desired travelling wave and deflection. The stubs are of such shape and spacing to establish a critical mathemitical relationship. (AEC)

  19. The use of magnetic resonance spectroscopy as a tool for the measurement of bihemispheric transcranial electric stimulation effects on primary motor cortex metabolism

    PubMed Central

    Tremblay, Sara; Beaulé, Vincent; Proulx, Sébastien; Lafleur, Louis-Philippe; Doyon, Julien; Marjańska, Małgorzata; Théoret, Hugo

    2015-01-01

    Transcranial direct current stimulation (tDCS) is a neuromodulation technique that has been increasingly used over the past decade in the treatment of neurological and psychiatric disorders such as stroke and depression. Yet, the mechanisms underlying its ability to modulate brain excitability to improve clinical symptoms remains poorly understood 33. To help improve this understanding, proton magnetic resonance spectroscopy (1H-MRS) can be used as it allows the in vivo quantification of brain metabolites such as γ-aminobutyric acid (GABA) and glutamate in a region-specific manner 35. In fact, a recent study demonstrated that 1H-MRS is indeed a powerful means to better understand the effects of tDCS on neurotransmitter concentration 34. This article aims to describe the complete protocol for combining tDCS (NeuroConn MR compatible stimulator) with 1H-MRS at 3 T using a MEGA-PRESS sequence. We will describe the impact of a protocol that has shown great promise for the treatment of motor dysfunctions after stroke, which consists of bilateral stimulation of primary motor cortices 27,30,31. Methodological factors to consider and possible modifications to the protocol are also discussed. PMID:25490453

  20. Double Fano resonances in plasmon coupling nanorods

    NASA Astrophysics Data System (ADS)

    Liu, Fei; Jin, Jie

    2015-05-01

    Fano resonances are investigated in nanorods with symmetric lengths and side-by-side assembly. Single Fano resonance can be obtained by a nanorod dimer, and double Fano resonances are shown in nanorod trimers with side-by-side assembly. With transverse plasmon excitation, Fano resonances are caused by the destructive interference between a bright superradiant mode and dark subradiant modes. The bright mode originates from the electric plasmon resonance, and the dark modes originate from the magnetic resonances induced by near-field inter-rod coupling. Double Fano resonances result from double dark modes at different wavelengths, which are induced and tuned by the asymmetric gaps between the adjacent nanorods. Fano resonances show a high figure of merit and large light extinction in the periodic array of assembled nanorods, which can potentially be used in multiwavelength sensing in the visible and near-infrared regions.

  1. Resonant Tunneling Spin Pump

    NASA Technical Reports Server (NTRS)

    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.

  2. RESONATOR PARTICLE SEPARATOR

    DOEpatents

    Blewett, J.P.

    1962-01-01

    A wave guide resonator structure is described for use in separating particles of equal momentum but differing in mass and having energies exceeding one billion electron volts. The particles are those of sub-atomic size and are generally produced as a result of the bombardment of a target by a beam such as protons produced in a high-energy accelerator. In this wave guide construction, the particles undergo preferential deflection as a result of the presence of an electric field. The boundary conditions established in the resonator are such as to eliminate an interfering magnetic component, and to otherwise phase the electric field to obtain a traveling wave such as one which moves at the same speed as the unwanted particle. The latter undergoes continuous deflection over the whole length of the device and is, therefore, eliminated while the wanted particle is deflected in opposite directions over the length of the resonator and is thus able to enter an exit aperture. (AEC)

  3. Ion electric propulsion unit

    DOEpatents

    Light, Max E; Colestock, Patrick L

    2014-01-28

    An electron cyclotron resonance (ECR) thruster is disclosed having a plasma chamber which is electrically biased with a positive voltage. The chamber bias serves to efficiently accelerate and expel the positive ions from the chamber. Electrons follow the exiting ions, serving to provide an electrically neutral exhaust plume. In a further embodiment, a downstream shaping magnetic field serves to further accelerate and/or shape the exhaust plume.

  4. Josephson Junctions Help Measure Resonance And Dispersion

    NASA Technical Reports Server (NTRS)

    Javadi, Hamid H. S.; Mcgrath, William R.; Bumble, Bruce; Leduc, Henry G.

    1994-01-01

    Electrical characteristics of superconducting microstrip transmission lines measured at millimeter and submillimeter wavelengths. Submicron Josephson (super-conductor/insulator/superconductor) junctions used as both voltage-controlled oscillators and detectors to measure frequencies (in range of hundreds of gigahertz) of high-order resonant electromagnetic modes of superconducting microstrip transmission-line resonators. This oscillator/detector approach similar to vacuum-tube grid dip meters and transistor dip meters used to probe resonances at much lower frequencies.

  5. Radio frequency quadrupole resonator for linear accelerator

    DOEpatents

    Moretti, Alfred

    1985-01-01

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

  6. A microwave dielectric resonant oscillatory circuit

    NASA Astrophysics Data System (ADS)

    Sigov, A. S.; Shvartsburg, A. B.

    2016-07-01

    Bias currents in a thin dielectric nonconducting torus are investigated, and the resonant mode of excitation of these currents is established. The similarity of the frequency spectrum of such a dielectric element to the spectra of a classical Thomson oscillatory circuit and a metamaterial with negative permittivity is demonstrated. The resonant frequency of electromagnetic oscillations of the ring dielectric circuit and magnetic and electric fields of such a circuit under resonant excitation are determined.

  7. Thermoacoustic magnetohydrodynamic electrical generator

    DOEpatents

    Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1986-01-01

    A thermoacoustic magnetohydrodynamic electrical generator includes an intrinsically irreversible thermoacoustic heat engine coupled to a magnetohydrodynamic electrical generator. The heat engine includes an electrically conductive liquid metal as the working fluid and includes two heat exchange and thermoacoustic structure assemblies which drive the liquid in a push-pull arrangement to cause the liquid metal to oscillate at a resonant acoustic frequency on the order of 1,000 Hz. The engine is positioned in the field of a magnet and is oriented such that the liquid metal oscillates in a direction orthogonal to the field of the magnet, whereby an alternating electrical potential is generated in the liquid metal. Low-loss, low-inductance electrical conductors electrically connected to opposite sides of the liquid metal conduct an output signal to a transformer adapted to convert the low-voltage, high-current output signal to a more usable higher voltage, lower current signal.

  8. Thermoacoustic magnetohydrodynamic electrical generator

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1984-11-16

    A thermoacoustic magnetohydrodynamic electrical generator includes an intrinsically irreversible thermoacoustic heat engine coupled to a magnetohydrodynamic electrical generator. The heat engine includes an electrically conductive liquid metal as the working fluid and includes two heat exchange and thermoacoustic structure assemblies which drive the liquid in a push-pull arrangement to cause the liquid metal to oscillate at a resonant acoustic frequency on the order of 1000 Hz. The engine is positioned in the field of a magnet and is oriented such that the liquid metal oscillates in a direction orthogonal to the field of the magnet, whereby an alternating electrical potential is generated in the liquid metal. Low-loss, low-inductance electrical conductors electrically connected to opposite sides of the liquid metal conduct an output signal to a transformer adapted to convert the low-voltage, high-current output signal to a more usable higher voltage, lower current signal.

  9. Electrically modulated magnetoelectric sensors

    NASA Astrophysics Data System (ADS)

    Hayes, P.; Salzer, S.; Reermann, J.; Yarar, E.; Röbisch, V.; Piorra, A.; Meyners, D.; Höft, M.; Knöchel, R.; Schmidt, G.; Quandt, E.

    2016-05-01

    Magnetoelectric thin film composites have demonstrated their potential to detect sub-pT magnetic fields if mechanical resonances (typically few hundred Hz to a few kHz) are utilized. At low frequencies (1-100 Hz), magnetic field-induced frequency conversion has enabled wideband measurements with resonance-enhanced sensitivities by using the nonlinear characteristics of the magnetostriction curve. Nevertheless, the modulation with a magnetic field with a frequency close to the mechanical resonance results in a number of drawbacks, which are, e.g., size and energy consumption of the sensor as well as potential crosstalk in sensor arrays. In this work, we demonstrate the feasibility of an electric frequency conversion of a magnetoelectric sensor which would overcome the drawbacks of magnetic frequency conversion. This magnetoelectric sensor consists of three functional layers: an exchange biased magnetostrictive multilayer showing a high piezomagnetic coefficient without applying a magnetic bias field, a non-linear piezoelectric actuation layer and a linear piezoelectric sensing layer. In this approach, the low frequency magnetic signal is shifted into the mechanical resonance of the sensor, while the electric modulation frequency is chosen to be either the difference or the sum of the resonance and the signal frequency. Using this electric frequency conversion, a limit of detection in the low nT/Hz1/2 range was shown for signals of low frequency.

  10. Piezoelectric shear wave resonator and method of making same

    DOEpatents

    Wang, J.S.; Lakin, K.M.; Landin, A.R.

    1985-05-20

    An acoustic shear wave resonator comprising a piezoelectric film having its C-axis substantially inclined from the film normal such that the shear wave coupling coefficient significantly exceeds the longitudinal wave coupling coefficient, whereby the film is capable of shear wave resonance, and means for exciting said film to resonate. The film is prepared by deposition in a dc planar magnetron sputtering system to which a supplemental electric field is applied. The resonator structure may also include a semiconductor material having a positive temperature coefficient of resonance such that the resonator has a temperature coefficient of resonance approaching 0 ppM//sup 0/C.

  11. Piezoelectric shear wave resonator and method of making same

    DOEpatents

    Wang, Jin S.; Lakin, Kenneth M.; Landin, Allen R.

    1988-01-01

    An acoustic shear wave resonator comprising a piezoelectric film having its C-axis substantially inclined from the film normal such that the shear wave coupling coefficient significantly exceeds the longitudinal wave coupling coefficient, whereby the film is capable of shear wave resonance, and means for exciting said film to resonate. The film is prepared by deposition in a dc planar magnetron sputtering system to which a supplemental electric field is applied. The resonator structure may also include a semiconductor material having a positive temperature coefficient of resonance such that the resonator has a temperature coefficient of resonance approaching 0 ppm/.degree.C.

  12. Piezoelectric shear wave resonator and method of making same

    DOEpatents

    Wang, J.S.; Lakin, K.M.; Landin, A.R.

    1983-10-25

    An acoustic shear wave resonator comprising a piezoelectric film having its C-axis substantially inclined from the film normal such that the shear wave coupling coefficient significantly exceeds the longitudinal wave coupling coefficient, whereby the film is capable of shear wave resonance, and means for exciting said film to resonate. The film is prepared by deposition in a dc planar magnetron sputtering system to which a supplemental electric field is applied. The resonator structure may also include a semiconductor material having a positive temperature coefficient of resonance such that the resonator has a temperature coefficient of resonance approaching 0 ppM//sup 0/C.

  13. Method of making a piezoelectric shear wave resonator

    DOEpatents

    Wang, Jin S.; Lakin, Kenneth M.; Landin, Allen R.

    1987-02-03

    An acoustic shear wave resonator comprising a piezoelectric film having its C-axis substantially inclined from the film normal such that the shear wave coupling coefficient significantly exceeds the longitudinal wave coupling coefficient, whereby the film is capable of shear wave resonance, and means for exciting said film to resonate. The film is prepared by deposition in a dc planar magnetron sputtering system to which a supplemental electric field is applied. The resonator structure may also include a semiconductor material having a positive temperature coefficient of resonance such that the resonator has a temperature coefficient of resonance approaching 0 ppm/.degree.C.

  14. Wireless Electrical Device Using Open-Circuit Elements Having No Electrical Connections

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E. (Inventor); Taylor, Bryant Douglas (Inventor)

    2012-01-01

    A wireless electrical device includes an electrically unconnected electrical conductor and at least one electrically unconnected electrode spaced apart from the electrical conductor. The electrical conductor is shaped for storage of an electric field and a magnetic field. In the presence of a time-varying magnetic field, the electrical conductor so-shaped resonates to generate harmonic electric and magnetic field responses. Each electrode is at a location lying within the magnetic field response so-generated and is constructed such that a linear movement of electric charges is generated in each electrode due to the magnetic field response so-generated.

  15. Discrete resonances

    NASA Astrophysics Data System (ADS)

    Vivaldi, Franco

    2015-12-01

    The concept of resonance has been instrumental to the study of Hamiltonian systems with divided phase space. One can also define such systems over discrete spaces, which have a finite or countable number of points, but in this new setting the notion of resonance must be re-considered from scratch. I review some recent developments in the area of arithmetic dynamics which outline some salient features of linear and nonlinear stable (elliptic) orbits over a discrete space, and also underline the difficulties that emerge in their analysis.

  16. Discrete resonances

    NASA Astrophysics Data System (ADS)

    Vivaldi, Franco

    The concept of resonance has been instrumental to the study of Hamiltonian systems with divided phase space. One can also define such systems over discrete spaces, which have a finite or countable number of points, but in this new setting the notion of resonance must be re-considered from scratch. I review some recent developments in the area of arithmetic dynamics which outline some salient features of linear and nonlinear stable (elliptic) orbits over a discrete space, and also underline the difficulties that emerge in their analysis.

  17. Laser Resonator

    NASA Technical Reports Server (NTRS)

    Harper, L. L. (Inventor)

    1983-01-01

    An optical resonator cavity configuration has a unitary mirror with oppositely directed convex and concave reflective surfaces disposed into one fold and concertedly reversing both ends of a beam propagating from a laser rod disposed between two total internal reflection prisms. The optical components are rigidly positioned with perpendicularly crossed virtual rooflines by a compact optical bed. The rooflines of the internal reflection prisms, are arranged perpendicularly to the axis of the laser beam and to the optical axes of the optical resonator components.

  18. Cavities for electron spin resonance: predicting the resonant frequency

    NASA Astrophysics Data System (ADS)

    Colton, John; Miller, Kyle; Meehan, Michael; Spencer, Ross

    Microwave cavities are used in electron spin resonance to enhance magnetic fields. Dielectric resonators (DRs), pieces of high dielectric material, can be used to tailor the resonant frequency of a cavity. However, designing cavities with DRs to obtain desired frequencies is challenging and in general can only be done numerically with expensive software packages. We present a new method for calculating the resonant frequencies and corresponding field modes for cylindrically symmetric cavities and apply it to a cavity with vertically stacked DRs. The modes of an arbitrary cavity are expressed as an expansion of empty cavity modes. The wave equation for D gives rise to an eigenvalue equation whose eigenvalues are the resonant frequencies and whose eigenvectors yield the electric and magnetic fields of the mode. A test against theory for an infinitely long dielectric cylinder inside an infinite cavity yields an accuracy better than 0.4% for nearly all modes. Calculated resonant frequencies are also compared against experiment for quasi-TE011 modes in resonant cavities with ten different configurations of DRs; experimental results agree with predicted values with an accuracy better than 1.0%. MATLAB code is provided at http://www.physics.byu.edu/research/coltonlab/cavityresonance.

  19. Advances in mechanical detection of magnetic resonance

    PubMed Central

    Kuehn, Seppe; Hickman, Steven A.; Marohn, John A.

    2008-01-01

    The invention and initial demonstration of magnetic resonance force microscopy (MRFM) in the early 1990s launched a renaissance of mechanical approaches to detecting magnetic resonance. This article reviews progress made in MRFM in the last decade, including the demonstration of scanned probe detection of magnetic resonance (electron spin resonance, ferromagnetic resonance, and nuclear magnetic resonance) and the mechanical detection of electron spin resonance from a single spin. Force and force-gradient approaches to mechanical detection are reviewed and recent related work using attonewton sensitivity cantilevers to probe minute fluctuating electric fields near surfaces is discussed. Given recent progress, pushing MRFM to single proton sensitivity remains an exciting possibility. We will survey some practical and fundamental issues that must be resolved to meet this challenge. PMID:18266413

  20. Laboratory Manual, Electrical Engineering 25.

    ERIC Educational Resources Information Center

    Syracuse Univ., NY. Dept. of Electrical Engineering.

    Developed as part of a series of materials in the electrical engineering sequence developed under contract with the United States Office of Education, this laboratory manual provides nine laboratory projects suitable for a second course in electrical engineering. Dealing with resonant circuits, electrostatic fields, magnetic devices, and…

  1. Mie resonance in the arrays of dielectric rods in air

    NASA Astrophysics Data System (ADS)

    Dalal, Reena; Kalra, Yogita; Sinha, R. K.

    2015-09-01

    Mie resonance in square arrays of dielectric rods has been reported. Arrays in square lattice of dielectric rods with very high permittivity in air have been considered. Light of transverse electric mode has been launched on the square array of cylindrical dielectric rods. Mie resonance of first two orders has been observed in the dielectric rods, due to which electric and magnetic dipoles are generated in the rods. Thus, electric resonance and magnetic resonance at different frequencies has been observed with material of high value of permittivity.

  2. Resonant behavior of dielectric objects (electrostatic resonances).

    PubMed

    Fredkin, D R; Mayergoyz, I D

    2003-12-19

    Resonant behavior of dielectric objects occurs at certain frequencies for which the object permittivity is negative and the free-space wavelength is large in comparison with the object dimensions. Unique physical features of these resonances are studied and a novel technique for the calculation of resonance values of permittivity, and hence resonance frequencies, is proposed. Scale invariance of resonance frequencies, unusually strong orthogonality properties of resonance modes, and a two-dimensional phenomenon of "twin" spectra are reported. The paper concludes with brief discussions of optical controllability of these resonances in semiconductor nanoparticles and a plausible, electrostatic resonance based, mechanism for nucleation and formation of ball lightning. PMID:14754117

  3. Electric field modulation of ultra-high resonance frequency in obliquely deposited [Pb(Mg1/3Nb2/3)O3]0.68-[PbTiO3]0.32(011)/FeCoZr heterostructure for reconfigurable magnetoelectric microwave devices

    NASA Astrophysics Data System (ADS)

    Phuoc, Nguyen N.; Ong, C. K.

    2014-07-01

    The multiferroic heterostructure of FeCoZr/[Pb(Mg1/3Nb2/3)O3]0.68-[PbTiO3]0.32(011) (PMN-PT) prepared by oblique sputtering deposition technique shows a large electrical tunability of ultra-high ferromagnetic resonance frequency from 7.4 GHz to 12.3 GHz. Moreover, we experimentally demonstrate the possibility of realizing electrically reconfigurable magnetoelectric microwave devices with ultra-low power consumption by employing the heterostructure under different resetting electric fields through a reconfiguration process. In particular, the tunability of the FeCoZr/PMN-PT heterostructure from 8.2 GHz to 11.6 GHz can retain in a remanent state after releasing the resetting electric field. This suggests that the tunable microwave devices based on such heterostructures are permanently reconfigurable by simply using a trigger electric field double-pulse which requires much less energy than that of the conventional ones wherein an electric field needs to be constantly applied during operation.

  4. Fano resonances from gradient-index metamaterials

    NASA Astrophysics Data System (ADS)

    Xu, Yadong; Li, Sucheng; Hou, Bo; Chen, Huanyang

    2016-01-01

    Fano resonances - resonant scattering features with a characteristic asymmetric profile - have generated much interest, due to their extensive and valuable applications in chemical or biological sensors, new types of optical switches, lasers and nonlinear optics. They have been observed in a wide variety of resonant optical systems, including photonic crystals, metamaterials, metallic gratings and nanostructures. In this work, a waveguide structure is designed by employing gradient-index metamaterials, supporting strong Fano resonances with extremely sharp spectra. As the changes in the transmission spectrum originate from the interaction of guided modes from different channels, instead of resonance structures or metamolecules, the Fano resonances can be observed for both transverse electric and transverse magnetic polarizations. These findings are verified by fine agreement with analytical calculations and experimental results at microwave, as well as simulated results at near infrared frequencies.

  5. Fano resonances from gradient-index metamaterials.

    PubMed

    Xu, Yadong; Li, Sucheng; Hou, Bo; Chen, Huanyang

    2016-01-01

    Fano resonances - resonant scattering features with a characteristic asymmetric profile - have generated much interest, due to their extensive and valuable applications in chemical or biological sensors, new types of optical switches, lasers and nonlinear optics. They have been observed in a wide variety of resonant optical systems, including photonic crystals, metamaterials, metallic gratings and nanostructures. In this work, a waveguide structure is designed by employing gradient-index metamaterials, supporting strong Fano resonances with extremely sharp spectra. As the changes in the transmission spectrum originate from the interaction of guided modes from different channels, instead of resonance structures or metamolecules, the Fano resonances can be observed for both transverse electric and transverse magnetic polarizations. These findings are verified by fine agreement with analytical calculations and experimental results at microwave, as well as simulated results at near infrared frequencies. PMID:26813107

  6. Electroelastic effect of thickness mode langasite resonators.

    PubMed

    Zhang, Haifeng; Turner, Joseph A; Yang, Jiashi; Kosinski, John A

    2007-10-01

    Langasite is a very promising material for resonators due to its good temperature behavior and high piezoelectric coupling, low acoustic loss, and high Q factor. The biasing effect for langasite resonators is crucial for resonator design. In this article, the resonant frequency shift of a thickness-mode langasite resonator is analyzed with respect to a direct current (DC) electric field applied in the thickness direction. The vibration modes of a thin langasite plate fully coated with an electrode are analyzed. The analysis is based on the theory for small fields superposed on a bias in electroelastic bodies and the first-order perturbation integral theory. The electroelastic effect of the resonator is analyzed by both analytical and finite-element methods. The complete set of nonlinear elastic, piezoelectric, dielectric permeability, and electrostrictive constants of langasite is used in the theoretical and numerical analysis. The sensitivity of electroelastic effect to nonlinear material constants is analyzed. PMID:18019250

  7. Fano resonances from gradient-index metamaterials

    PubMed Central

    Xu, Yadong; Li, Sucheng; Hou, Bo; Chen, Huanyang

    2016-01-01

    Fano resonancesresonant scattering features with a characteristic asymmetric profile – have generated much interest, due to their extensive and valuable applications in chemical or biological sensors, new types of optical switches, lasers and nonlinear optics. They have been observed in a wide variety of resonant optical systems, including photonic crystals, metamaterials, metallic gratings and nanostructures. In this work, a waveguide structure is designed by employing gradient-index metamaterials, supporting strong Fano resonances with extremely sharp spectra. As the changes in the transmission spectrum originate from the interaction of guided modes from different channels, instead of resonance structures or metamolecules, the Fano resonances can be observed for both transverse electric and transverse magnetic polarizations. These findings are verified by fine agreement with analytical calculations and experimental results at microwave, as well as simulated results at near infrared frequencies. PMID:26813107

  8. Development of new atomic scale defect identification schemes in micro / nanoelectronics incorporating digital signal processing methods for investigating zero/low field spin dependent transport and passage effects in electrically detected magnetic resonance

    NASA Astrophysics Data System (ADS)

    Cochrane, Corey J.

    This work focuses on the development of new techniques for the study of spin dependent transport and trapping centers in fully processed micro and nanoelectronics. The first, and most interesting, technique offers a very low cost means to study spin dependent transport in microelectronics as an alternative to electrically detected magnetic resonance (EDMR). EDMR measurements generally require strong static magnetic fields, typically 3 kG or greater, and high frequency oscillating electromagnetic fields, typically 9 GHz or higher. In this work, it is demonstrated that large spin dependent recombination and tunneling signals can be detected in the absence of the oscillating electromagnetic field at zero magnetic field. The physics behind this technique is based upon the mixing of singlet and triplet energy states of the electron spin pairs involved in the spin dependent processes. In this study, we show that this technique can be applied to Si and SiC based devices. Theoretically, it can be applicable to devices of all material systems in which defects play a role in spin dependent transport, some of which include CdTe and GaN. Although the resolution of the g value is sacrificed in this new measurement, the technique can detect electron-nuclear hyperfine interactions and possibly dipolar and exchange interactions. The technique also has great promise in microelectronic device reliability studies as it is directly applicable to time dependent dielectric breakdown in thin film dielectrics and bias temperature instabilities in transistors. Other applications of this new physics include self-calibrating magnetometers, spin based memories, quantum computation, and miniature EDMR spectrometers for wafer probing stations. The second technique involves the utilization of passage effects that arise when performing magnetic field modulation in EDMR. When certain conditions are met, the higher order harmonics of the spin dependent signal can contain much useful information

  9. Acoustically-Induced Electrical Signals

    NASA Astrophysics Data System (ADS)

    Brown, S. R.

    2014-12-01

    We have observed electrical signals excited by and moving along with an acoustic pulse propagating in a sandstone sample. Using resonance we are now studying the characteristics of this acousto-electric signal and determining its origin and the controlling physical parameters. Four rock samples with a range of porosities, permeabilities, and mineralogies were chosen: Berea, Boise, and Colton sandstones and Austin Chalk. Pore water salinity was varied from deionized water to sea water. Ag-AgCl electrodes were attached to the sample and were interfaced to a 4-wire electrical resistivity system. Under computer control, the acoustic signals were excited and the electrical response was recorded. We see strong acoustically-induced electrical signals in all samples, with the magnitude of the effect for each rock getting stronger as we move from the 1st to the 3rd harmonics in resonance. Given a particular fluid salinity, each rock has its own distinct sensitivity in the induced electrical effect. For example at the 2nd harmonic, Berea Sandstone produces the largest electrical signal per acoustic power input even though Austin Chalk and Boise Sandstone tend to resonate with much larger amplitudes at the same harmonic. Two effects are potentially responsible for this acoustically-induced electrical response: one the co-seismic seismo-electric effect and the other a strain-induced resistivity change known as the acousto-electric effect. We have designed experimental tests to separate these mechanisms. The tests show that the seismo-electric effect is dominant in our studies. We note that these experiments are in a fluid viscosity dominated seismo-electric regime, leading to a simple interpretation of the signals where the electric potential developed is proportional to the local acceleration of the rock. Toward a test of this theory we have measured the local time-varying acoustic strain in our samples using a laser vibrometer.

  10. If It's Resonance, What is Resonating?

    ERIC Educational Resources Information Center

    Kerber, Robert C.

    2006-01-01

    The phenomenon under the name "resonance," which, is based on the mathematical analogy between mechanical resonance and the behavior of wave functions in quantum mechanical exchange phenomena was described. The resonating system does not have a structure intermediate between those involved in the resonance, but instead a structure which is further…

  11. Lateral acoustic wave resonator comprising a suspended membrane of low damping resonator material

    DOEpatents

    Olsson, Roy H.; El-Kady; , Ihab F.; Ziaei-Moayyed, Maryam; Branch; , Darren W.; Su; Mehmet F.,; Reinke; Charles M.,

    2013-09-03

    A very high-Q, low insertion loss resonator can be achieved by storing many overtone cycles of a lateral acoustic wave (i.e., Lamb wave) in a lithographically defined suspended membrane comprising a low damping resonator material, such as silicon carbide. The high-Q resonator can sets up a Fabry-Perot cavity in a low-damping resonator material using high-reflectivity acoustic end mirrors, which can comprise phononic crystals. The lateral overtone acoustic wave resonator can be electrically transduced by piezoelectric couplers. The resonator Q can be increased without increasing the impedance or insertion loss by storing many cycles or wavelengths in the high-Q resonator material, with much lower damping than the piezoelectric transducer material.

  12. Acoustic metasurface with hybrid resonances.

    PubMed

    Ma, Guancong; Yang, Min; Xiao, Songwen; Yang, Zhiyu; Sheng, Ping

    2014-09-01

    An impedance-matched surface has the property that an incident wave generates no reflection. Here we demonstrate that by using a simple construction, an acoustically reflecting surface can acquire hybrid resonances and becomes impedance-matched to airborne sound at tunable frequencies, such that no reflection is generated. Each resonant cell of the metasurface is deep-subwavelength in all its spatial dimensions, with its thickness less than the peak absorption wavelength by two orders of magnitude. As there can be no transmission, the impedance-matched acoustic wave is hence either completely absorbed at one or multiple frequencies, or converted into other form(s) of energy, such as an electrical current. A high acoustic-electrical energy conversion efficiency of 23% is achieved. PMID:24880731

  13. Electrically driven optical antennas

    NASA Astrophysics Data System (ADS)

    Kern, Johannes; Kullock, René; Prangsma, Jord; Emmerling, Monika; Kamp, Martin; Hecht, Bert

    2015-09-01

    Unlike radiowave antennas, so far optical nanoantennas cannot be fed by electrical generators. Instead, they are driven by light or indirectly via excited discrete states in active materials in their vicinity. Here we demonstrate the direct electrical driving of an in-plane optical antenna by the broadband quantum-shot noise of electrons tunnelling across its feed gap. The spectrum of the emitted photons is determined by the antenna geometry and can be tuned via the applied voltage. Moreover, the direction and polarization of the light emission are controlled by the antenna resonance, which also improves the external quantum efficiency by up to two orders of magnitude. The one-material planar design offers facile integration of electrical and optical circuits and thus represents a new paradigm for interfacing electrons and photons at the nanometre scale, for example for on-chip wireless communication and highly configurable electrically driven subwavelength photon sources.

  14. Wave Motion Electric Generator

    SciTech Connect

    Jacobi, E. F.; Winkler, R. J.

    1983-12-27

    Set out herein is an electrical generator conformed for installation in a buoy, the generator comprising an inverted pendulum having two windings formed at the free end thereof and aligned to articulate between two end stops each provided with a magnetic circuit. As the loops thus pass through the magnetic circuit, electrical current is induced which may be rectified through a full way rectifier to charge up a storage battery. The buoy itself may be ballasted to have its fundamental resonance at more than double the wave frequency with the result that during each passing of a wave at least two induction cycles occur.

  15. Antiferromagnetic resonance excitation by terahertz magnetic field resonantly enhanced with split ring resonator

    SciTech Connect

    Mukai, Y.; Hirori, H.; Yamamoto, T.; Kageyama, H.; Tanaka, K.

    2014-07-14

    Excitation of antiferromagnetic resonance (AFMR) in a HoFeO{sub 3} crystal combined with a split ring resonator (SRR) is studied using terahertz (THz) electromagnetic pulses. The magnetic field in the vicinity of the SRR is induced by the incident THz electric field component and excites spin oscillations that correspond to the AFMR, which are directly probed by the Faraday rotation of the polarization of a near-infrared probe pulse. The good agreement of the temperature-dependent magnetization dynamics with the calculation using the two-lattice Landau-Lifshitz-Gilbert equation confirms that the AFMR is excited by the THz magnetic field, which is enhanced at the SRR resonance frequency by a factor of 20 compared to the incident magnetic field.

  16. Topological Insulator Realized with Piezoelectric Resonators

    NASA Astrophysics Data System (ADS)

    McHugh, S.

    2016-07-01

    We propose a realization of a two-dimensional topological insulator using an array of microwave piezoelectric resonators. The resonators are coupled electrically, but acoustically isolated. The inter-resonator electromagnetic coupling required to reproduce an effective mechanical topological insulator is found explicitly. Both the acoustic and electric response show the essential features of topological insulator, e.g., helical edge states. The helical edge states may be useful for engineering nonreciprocal electronic devices like isolators and circulators. These components do not often appear in the radios of modern mobile phones since they traditionally require bulky magnetic material. However, a nonreciprocal device based on piezoelectric resonators may meet the demands of phone manufacturers due to their small size, high-linearity, and ease of fabrication.

  17. Tunable Optical Filters Having Electro-optic Whispering-gallery-mode Resonators

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy (Inventor); Ilchenko, Vladimir (Inventor); Matsko, Andrey B. (Inventor); Maleki, Lutfollah (Inventor)

    2006-01-01

    Tunable optical filters using whispering-gallery-mode (WGM) optical resonators are described. The WGM optical resonator in a filter exhibits an electro-optical effect and hence is tunable by applying a control electrical signal.

  18. Subwavelength resonant antennas enhancing electromagnetic energy harvesting

    NASA Astrophysics Data System (ADS)

    Oumbe Tekam, Gabin; Ginis, Vincent; Seetharamdoo, Divitha; Danckaert, Jan

    2016-04-01

    In this work, an electromagnetic energy harvester operating at microwave frequencies is designed based on a cut- wire metasurface. This metamaterial is known to contain a quasistatic electric dipole resonator leading to a strong resonant electric response when illuminated by electromagnetic fields.1 Starting from an equivalent electrical circuit, we analytically design the parameters of the system to tune the resonance frequency of the harvester at the desired frequency band. Subsequently, we compare these results with numerical simulations, which have been obtained using finite elements numerical simulations. Finally, we optimize the design by investigating the best arrangement for energy harvesting by coupling in parallel and in series many single layers of cut-wire metasurfaces. We also discuss the implementation of different geometries and sizes of the cut-wire metasurface for achieving different center frequencies and bandwidths.

  19. Tailoring dielectric resonator geometries for directional scattering and Huygens' metasurfaces

    NASA Astrophysics Data System (ADS)

    Campione, Salvatore; Basilio, Lorena I.; Warne, Larry K.; Sinclair, Michael B.

    2015-02-01

    In this paper we describe a methodology for tailoring the design of metamaterial dielectric resonators, which represent a promising path toward low-loss metamaterials at optical frequencies. We first describe a procedure to decompose the far field scattered by subwavelength resonators in terms of multipolar field components, providing explicit expressions for the multipolar far fields. We apply this formulation to confirm that an isolated high-permittivity cube resonator possesses frequency separated electric and magnetic dipole resonances, as well as a magnetic quadrupole resonance in close proximity to the electric dipole resonance. We then introduce multiple dielectric gaps to the resonator geometry in a manner suggested by perturbation theory, and demonstrate the ability to overlap the electric and magnetic dipole resonances, thereby enabling directional scattering by satisfying the first Kerker condition. We further demonstrate the ability to push the quadrupole resonance away from the degenerate dipole resonances to achieve local behavior. These properties are confirmed through the multipolar expansion and show that the use of geometries suggested by perturbation theory is a viable route to achieve purely dipole resonances for metamaterial applications such as wave-front manipulation with Huygens' metasurfaces. Our results are fully scalable across any frequency bands where high-permittivity dielectric materials are available, including microwave, THz, and infrared frequencies.

  20. Method of making a quartz resonator

    DOEpatents

    Vig, John R.; Filler, Raymond L.; Peters, R. Donald; Frank, James M.

    1981-01-01

    A quartz resonator is made from a chemically polished quartz plate. The plate is placed in an enclosure fitted with at least three mounting clips to receive the plate. The plate is secured to the clips with an electrically conductive adhesive capable of withstanding operation at 350 degrees C. The assembly is cleaned and a metallic electrode deposited onto the plate until the desired frequency is reached. The enclosure is then hermetically sealed. The resulting resonator can consistently withstand extremely high shocks.

  1. Electrical injury

    MedlinePlus

    ... damage, especially to the heart, muscles, or brain. Electric current can cause injury in three ways: Cardiac arrest ... How long you were in contact with the electricity How the electricity moved through your body Your ...

  2. Opto-electronic oscillators having optical resonators

    NASA Technical Reports Server (NTRS)

    Yao, Xiaotian Steve (Inventor); Maleki, Lutfollah (Inventor); Ilchenko, Vladimir (Inventor)

    2003-01-01

    Systems and techniques of incorporating an optical resonator in an optical part of a feedback loop in opto-electronic oscillators. This optical resonator provides a sufficiently long energy storage time and hence to produce an oscillation of a narrow linewidth and low phase noise. Certain mode matching conditions are required. For example, the mode spacing of the optical resonator is equal to one mode spacing, or a multiplicity of the mode spacing, of an opto-electronic feedback loop that receives a modulated optical signal and to produce an electrical oscillating signal.

  3. Buckled diamond-like carbon nanomechanical resonators.

    PubMed

    Tomi, Matti; Isacsson, Andreas; Oksanen, Mika; Lyashenko, Dmitry; Kaikkonen, Jukka-Pekka; Tervakangas, Sanna; Kolehmainen, Jukka; Hakonen, Pertti J

    2015-09-21

    We have developed capacitively-transduced nanomechanical resonators using sp(2)-rich diamond-like carbon (DLC) thin films as conducting membranes. The electrically conducting DLC films were grown by physical vapor deposition at a temperature of 500 °C. Characterizing the resonant response, we find a larger than expected frequency tuning that we attribute to the membrane being buckled upwards, away from the bottom electrode. The possibility of using buckled resonators to increase frequency tuning can be of advantage in rf applications such as tunable GHz filters and voltage-controlled oscillators. PMID:26284626

  4. Regenerative feedback resonant circuit

    DOEpatents

    Jones, A. Mark; Kelly, James F.; McCloy, John S.; McMakin, Douglas L.

    2014-09-02

    A regenerative feedback resonant circuit for measuring a transient response in a loop is disclosed. The circuit includes an amplifier for generating a signal in the loop. The circuit further includes a resonator having a resonant cavity and a material located within the cavity. The signal sent into the resonator produces a resonant frequency. A variation of the resonant frequency due to perturbations in electromagnetic properties of the material is measured.

  5. Can we trust the relationship between resonance poles and lifetimes?

    NASA Astrophysics Data System (ADS)

    Herbst, Ira; Mavi, Rajinder

    2016-05-01

    We show that the shape resonances induced by a one-dimensional well of delta functions disappear as soon asa small constant electric field is applied. In particular, in any compact subset of \\{z :{Re}z\\gt 0,{Im} {{z}}\\lt 0\\} there are no resonances if the non-zero field is small enough. In contrast to the lack of convergence of the lifetimes computed from the widths of the resonances we show that the ‘experimental lifetimes’ are continuous at zero field. The shape resonances are replaced by an infinite set of other resonances whose location and number we analyze.

  6. Measuring frequency response of surface-micromachined resonators

    NASA Astrophysics Data System (ADS)

    Cowan, William D.; Bright, Victor M.; Dalton, George C.

    1997-09-01

    Resonator structures offer a unique mechanism for characterizing MEMS materials, but measuring the resonant frequency of microstructures is challenging. In this effort a network analyzer system was used to electrically characterize surface-micromachined resonator structures in a carefully controlled pressure and temperature environment.A microscope laser interferometer was used to confirm actual device deflections.Cantilever, comb, and piston resonators fabricated in the DARPA-sponsored MUMPs process were extensively tested. Measured resonator frequency results show reasonable agreement with analytic predictions computed using manufacturer measured film thickness and residual material stress. Alternatively the measured resonant frequency data can be used to extract materials data. Tuning of resonant frequency with DC bias was also investigated. Because the tested devices vary widely in complexity, form a simple cantilever beam to a comb resonator, the data collected is especially well suited for validation testing of MEMS modeling codes.

  7. Quasiforbidden two-body Förster resonances in a cold Cs Rydberg gas

    NASA Astrophysics Data System (ADS)

    Pelle, B.; Faoro, R.; Billy, J.; Arimondo, E.; Pillet, P.; Cheinet, P.

    2016-02-01

    Cold Rydberg atoms are known to display dipole-dipole interaction-allowed resonances, also called Förster resonances, which lead to an efficient energy transfer when the proper electric field is used. This electric field also enables resonances, which do not respect the dipole-dipole selection rules under zero field. A few of these quasiforbidden resonances have been observed but they are often overlooked. Here we show that in cold 133Cs atoms there is a large number of these resonances that display a significant transfer efficiency due to their strong interactions, even at low electric field. We also develop a graphical method enabling us to find all possible resonances simultaneously. The resulting dramatic increase in the total number of addressable resonant energy transfers at different electric fields could have implications in the search for few-body interactions or macromolecules built from Rydberg atoms.

  8. A mechanistic interpretation of the resonant wave-particle interaction

    NASA Astrophysics Data System (ADS)

    Chim, Chi Yung; O'Neil, Thomas M.

    2016-05-01

    This paper provides a simple mechanistic interpretation of the resonant wave-particle interaction of Landau. For the simple case of a Langmuir wave in a Vlasov plasma, the non-resonant electrons satisfy an oscillator equation that is driven resonantly by the bare electric field from the resonant electrons, and in the case of wave damping, this complex driver field is of a phase to reduce the oscillation amplitude. The wave-particle resonant interaction also occurs in waves governed by 2D E × B drift dynamics, such as a diocotron wave. In this case, the bare electric field from the resonant electrons causes E × B drift motion back in the core plasma, reducing the amplitude of the wave.

  9. Excitation of plasmonic nanoantennas by nonresonant and resonant electron tunnelling.

    PubMed

    Uskov, Alexander V; Khurgin, Jacob B; Protsenko, Igor E; Smetanin, Igor V; Bouhelier, Alexandre

    2016-08-14

    A rigorous theory of photon emission generated by inelastic electron tunnelling inside the gap of plasmonic nanoantennas is developed. The disappointingly low efficiency of the electrical excitation of surface plasmon polaritons in these structures can be increased by orders of magnitude when a resonant tunnelling structure is incorporated inside the gap. A resonant tunnelling assisted surface plasmon emitter may become a key element in future electrically-driven plasmonic nanocircuits. PMID:27427159

  10. Biosensing by WGM Microspherical Resonators.

    PubMed

    Righini, Giancarlo C; Soria, Silvia

    2016-01-01

    Whispering gallery mode (WGM) microresonators, thanks to their unique properties, have allowed researchers to achieve important results in both fundamental research and engineering applications. Among the various geometries, microspheres are the simplest 3D WGM resonators; the total optical loss in such resonators can be extremely low, and the resulting extraordinarily high Q values of 10⁸-10⁸ lead to high energy density, narrow resonant-wavelength lines and a lengthy cavity ringdown. They can also be coated in order to better control their properties or to increase their functionality. Their very high sensitivity to changes in the surrounding medium has been exploited for several sensing applications: protein adsorption, trace gas detection, impurity detection in liquids, structural health monitoring of composite materials, detection of electric fields, pressure sensing, and so on. In the present paper, after a general introduction to WGM resonators, attention is focused on spherical microresonators, either in bulk or in bubble format, to their fabrication, characterization and functionalization. The state of the art in the area of biosensing is presented, and the perspectives of further developments are discussed. PMID:27322282

  11. Biosensing by WGM Microspherical Resonators

    PubMed Central

    Righini, Giancarlo C.; Soria, Silvia

    2016-01-01

    Whispering gallery mode (WGM) microresonators, thanks to their unique properties, have allowed researchers to achieve important results in both fundamental research and engineering applications. Among the various geometries, microspheres are the simplest 3D WGM resonators; the total optical loss in such resonators can be extremely low, and the resulting extraordinarily high Q values of 108–109 lead to high energy density, narrow resonant-wavelength lines and a lengthy cavity ringdown. They can also be coated in order to better control their properties or to increase their functionality. Their very high sensitivity to changes in the surrounding medium has been exploited for several sensing applications: protein adsorption, trace gas detection, impurity detection in liquids, structural health monitoring of composite materials, detection of electric fields, pressure sensing, and so on. In the present paper, after a general introduction to WGM resonators, attention is focused on spherical microresonators, either in bulk or in bubble format, to their fabrication, characterization and functionalization. The state of the art in the area of biosensing is presented, and the perspectives of further developments are discussed. PMID:27322282

  12. Composite Resonator Surface Emitting Lasers

    SciTech Connect

    FISCHER,ARTHUR J.; CHOQUETTE,KENT D.; CHOW,WENG W.; ALLERMAN,ANDREW A.; GEIB,KENT M.

    2000-05-01

    The authors have developed electrically-injected coupled-resonator vertical-cavity lasers and have studied their novel properties. These monolithically grown coupled-cavity structures have been fabricated with either one active and one passive cavity or with two active cavities. All devices use a selectively oxidized current aperture in the lower cavity, while a proton implant was used in the active-active structures to confine current in the top active cavity. They have demonstrated optical modulation from active-passive devices where the modulation arises from dynamic changes in the coupling between the active and passive cavities. The laser intensity can be modulated by either forward or reverse biasing the passive cavity. They have also observed Q-switched pulses from active-passive devices with pulses as short as 150 ps. A rate equation approach is used to model the Q-switched operation yielding good agreement between the experimental and theoretical pulseshape. They have designed and demonstrated the operation of active-active devices which la.se simultaneously at both longitudinal cavity resonances. Extremely large bistable regions have also been observed in the light-current curves for active-active coupled resonator devices. This bistability can be used for high contrast switching with contrast ratios as high as 100:1. Coupled-resonator vertical-cavity lasers have shown enhanced mode selectivity which has allowed devices to lase with fundamental-mode output powers as high as 5.2 mW.

  13. Radio-frequency quadrupole resonator for linear accelerator

    DOEpatents

    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. The Frahm Resonance Apparatus: Variations on a Theme

    ERIC Educational Resources Information Center

    Daffron, John A.; Greenslade, Thomas B., Jr.

    2013-01-01

    The Frahm resonance principle, in which resonating reeds indicate the frequency of mechanical or electrical oscillations, is a hardy perennial. In this note we will give some history, show some original apparatus, and show how it may be reproduced with relatively little effort.

  15. Method and apparatus for resonant frequency waveform modulation

    DOEpatents

    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.

  16. Split-resonator integrated-post MEMS gyroscope

    NASA Technical Reports Server (NTRS)

    Bae, Youngsam (Inventor); Hayworth, Ken J. (Inventor); Shcheglov, Kirill V. (Inventor)

    2004-01-01

    A split-resonator integrated-post vibratory microgyroscope may be fabricated using micro electrical mechanical systems (MEMS) fabrication techniques. The microgyroscope may include two gyroscope sections bonded together, each gyroscope section including resonator petals, electrodes, and an integrated half post. The half posts are aligned and bonded to act as a single post.

  17. Cavity- and waveguide-resonators in electron paramagnetic resonance, nuclear magnetic resonance, and magnetic resonance imaging.

    PubMed

    Webb, Andrew

    2014-11-01

    Cavity resonators are widely used in electron paramagnetic resonance, very high field magnetic resonance microimaging and also in high field human imaging. The basic principles and designs of different forms of cavity resonators including rectangular, cylindrical, re-entrant, cavity magnetrons, toroidal cavities and dielectric resonators are reviewed. Applications in EPR and MRI are summarized, and finally the topic of traveling wave MRI using the magnet bore as a waveguide is discussed. PMID:25456314

  18. Nonlinear response of magnetoplasmon resonance

    NASA Astrophysics Data System (ADS)

    Hatke, Anthony; Zudov, Michael; Manfra, Michael

    2012-02-01

    Magnetoplasmon resonances have been observed in microwave photoresistance of Hall bar-shaped two-dimensional electron systems more than two decateds ago. This talk will report on such a resonance in a very high mobility two-dimensional electron gas where it appears as a distinct photoresistivity peak superimposed on a microwave-induced zero-resistance state. In particular, we will discuss the response of this peak to dc electric field. A portion of this work was performed at the National High Magnetic Field Laboratory which is supported by NSF Cooperative Agreement No. DMR-0654118, by the State of Florida, and the DOE. The work at Minnesota was supported by DOE Grant No. DE-SC002567 and NSF Grant No. DMR-0548014. The work at Purdue was supported by DOE grant de-sc0006671.

  19. Magnetic resonance of slotted circular cylinder resonators

    NASA Astrophysics Data System (ADS)

    Du, Junjie; Liu, Shiyang; Lin, Zhifang; Chui, S. T.

    2008-07-01

    By a rigorous full-wave approach, a systemic study is made on the magnetic resonance of slotted circular cylinder resonators (SCCRs) made of a perfect conductor for the lossless case. This is a two-dimensional analog of the split-ring resonator and may serve as an alternative type of essential constituent of electromagnetic metamaterials. It is found that the resonance frequency can be modulated by changing the geometrical parameters and the dielectrics filling in the cavity and the slot. An approximate empirical expression is presented for magnetic resonance frequency of SCCRs from the viewpoint of an L-C circuit system. Finally, it is demonstrated that the SCCR structure can be miniaturized to less than 1/150 resonant wavelength in size with the dielectrics available currently.

  20. Magnetic plasmonic Fano resonance at optical frequency.

    PubMed

    Bao, Yanjun; Hu, Zhijian; Li, Ziwei; Zhu, Xing; Fang, Zheyu

    2015-05-13

    Plasmonic Fano resonances are typically understood and investigated assuming electrical mode hybridization. Here we demonstrate that a purely magnetic plasmon Fano resonance can be realized at optical frequency with Au split ring hexamer nanostructure excited by an azimuthally polarized incident light. Collective magnetic plasmon modes induced by the circular electric field within the hexamer and each of the split ring can be controlled and effectively hybridized by designing the size and orientation of each ring unit. With simulated results reproducing the experiment, our suggested configuration with narrow line-shape magnetic Fano resonance has significant potential applications in low-loss sensing and may serves as suitable elementary building blocks for optical metamaterials. PMID:25594885

  1. Cascaded resonant bridge converters

    NASA Technical Reports Server (NTRS)

    Stuart, Thomas A. (Inventor)

    1989-01-01

    A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

  2. Electric emissions from electrical appliances.

    PubMed

    Leitgeb, N; Cech, R; Schröttner, J

    2008-01-01

    Electric emissions from electric appliances are frequently considered negligible, and standards consider electric appliances to comply without testing. By investigating 122 household devices of 63 different categories, it could be shown that emitted electric field levels do not justify general disregard. Electric reference values can be exceeded up to 11-fold. By numerical dosimetry with homogeneous human models, induced intracorporal electric current densities were determined and factors calculated to elevate reference levels to accounting for reduced induction efficiency of inhomogeneous fields. These factors were found not high enough to allow generally concluding on compliance with basic restrictions without testing. Electric appliances usually simultaneously emit both electric and magnetic fields exposing almost the same body region. Since the sum of induced current densities is limited, one field component reduces the available margin for the other. Therefore, superposition of electric current densities induced by either field would merit consideration. PMID:18083998

  3. Electrical Generation.

    ERIC Educational Resources Information Center

    Science and Children, 1990

    1990-01-01

    Described are two activities designed to help children investigate electrical charges, electric meters, and electromagnets. Included are background information, a list of materials, procedures, and follow-up questions. Sources of additional information are cited. (CW)

  4. Microelectromechanical filter formed from parallel-connected lattice networks of contour-mode resonators

    DOEpatents

    Wojciechowski, Kenneth E; Olsson, III, Roy H; Ziaei-Moayyed, Maryam

    2013-07-30

    A microelectromechanical (MEM) filter is disclosed which has a plurality of lattice networks formed on a substrate and electrically connected together in parallel. Each lattice network has a series resonant frequency and a shunt resonant frequency provided by one or more contour-mode resonators in the lattice network. Different types of contour-mode resonators including single input, single output resonators, differential resonators, balun resonators, and ring resonators can be used in MEM filter. The MEM filter can have a center frequency in the range of 10 MHz-10 GHz, with a filter bandwidth of up to about 1% when all of the lattice networks have the same series resonant frequency and the same shunt resonant frequency. The filter bandwidth can be increased up to about 5% by using unique series and shunt resonant frequencies for the lattice networks.

  5. Nonlinear Resonance Cones and Converging Plasma Blobs

    NASA Astrophysics Data System (ADS)

    Agmon, Nathan; Pribyl, Patrick; Gekelman, Walter; Wise, Joe; Katz, Cami; Ha, Chis; Baker, Bob

    2013-10-01

    Electric field resonance cones have been shown to create density disturbances in cold, magnetized plasmas. Two circular antennas in the LAPTAG experimental plasma device were used to create converging, nonlinear resonance cones. The nonlinear electrostatic field is produced by large amplitude RF (ERF/nkTe >> 1). A movable probe, powered by a computerized motor and consisting of three mutually orthogonal electric dipoles, is used to measure the electric field of the cones which become distorted at large amplitudes. A 2D movable Langmuir probe was used to determine localized density perturbations after turn-off of the RF power. A density blob moving at 3-5 times the ion sound speed has been observed to propagate away (for at least 20 cm) from the focus of the cone. Two ring antennas produced colliding blobs. The physics of the collision will be described. Work performed at the Basic Plasma Science Facility supported by DOE and NSF.

  6. Integral resonator gyroscope

    NASA Technical Reports Server (NTRS)

    Shcheglov, Kirill V. (Inventor); Challoner, A. Dorian (Inventor); Hayworth, Ken J. (Inventor); Wiberg, Dean V. (Inventor); Yee, Karl Y. (Inventor)

    2008-01-01

    The present invention discloses an inertial sensor having an integral resonator. A typical sensor comprises a planar mechanical resonator for sensing motion of the inertial sensor and a case for housing the resonator. The resonator and a wall of the case are defined through an etching process. A typical method of producing the resonator includes etching a baseplate, bonding a wafer to the etched baseplate, through etching the wafer to form a planar mechanical resonator and the wall of the case and bonding an end cap wafer to the wall to complete the case.

  7. Penetration of Schumann resonances into the upper ionosphere

    NASA Astrophysics Data System (ADS)

    Surkov, V. V.; Nosikova, N. S.; Plyasov, A. A.; Pilipenko, V. A.; Ignatov, V. N.

    2013-05-01

    Schumann resonances (SR) at ionospheric altitudes and in the atmosphere excited either by solitary lightning discharges or by the global thunderstorm activity, which is considered as Poisson stochastic process, are calculated and compared. The magnetic and electric resonant power spectra are investigated at low and high latitudes, for daytime and nighttime ionospheric parameters. We have analyzed the difference of spectral amplitudes and waves polarization on the ground surface and at the ionospheric altitudes. The calculated spectral amplitudes are in good agreement with the recent results detected by the electric sensors of the C/NOFS satellite. We have theoretically confirmed the feasibility of Schumann resonances observation by low orbiting satellites.

  8. Electric vehicles

    SciTech Connect

    Not Available

    1990-03-01

    Quiet, clean, and efficient, electric vehicles (EVs) may someday become a practical mode of transportation for the general public. Electric vehicles can provide many advantages for the nation's environment and energy supply because they run on electricity, which can be produced from many sources of energy such as coal, natural gas, uranium, and hydropower. These vehicles offer fuel versatility to the transportation sector, which depends almost solely on oil for its energy needs. Electric vehicles are any mode of transportation operated by a motor that receives electricity from a battery or fuel cell. EVs come in all shapes and sizes and may be used for different tasks. Some EVs are small and simple, such as golf carts and electric wheel chairs. Others are larger and more complex, such as automobile and vans. Some EVs, such as fork lifts, are used in industries. In this fact sheet, we will discuss mostly automobiles and vans. There are also variations on electric vehicles, such as hybrid vehicles and solar-powered vehicles. Hybrid vehicles use electricity as their primary source of energy, however, they also use a backup source of energy, such as gasoline, methanol or ethanol. Solar-powered vehicles are electric vehicles that use photovoltaic cells (cells that convert solar energy to electricity) rather than utility-supplied electricity to recharge the batteries. This paper discusses these concepts.

  9. Chemical Detection using Electrically Open Circuits having no Electrical Connections

    NASA Technical Reports Server (NTRS)

    Woodward, Stanley E.; Olgesby, Donald M.; Taylor, Bryant D.; Shams, Qamar A.

    2008-01-01

    This paper presents investigations to date on chemical detection using a recently developed method for designing, powering and interrogating sensors as electrically open circuits having no electrical connections. In lieu of having each sensor from a closed circuit with multiple electrically connected components, an electrically conductive geometric pattern that is powered using oscillating magnetic fields and capable of storing an electric field and a magnetic field without the need of a closed circuit or electrical connections is used. When electrically active, the patterns respond with their own magnetic field whose frequency, amplitude and bandwidth can be correlated with the magnitude of the physical quantities being measured. Preliminary experimental results of using two different detection approaches will be presented. In one method, a thin film of a reactant is deposited on the surface of the open-circuit sensor. Exposure to a specific targeted reactant shifts the resonant frequency of the sensor. In the second method, a coating of conductive material is placed on a thin non-conductive plastic sheet that is placed over the surface of the sensor. There is no physical contact between the sensor and the electrically conductive material. When the conductive material is exposed to a targeted reactant, a chemical reaction occurs that renders the material non-conductive. The change in the material s electrical resistance within the magnetic field of the sensor alters the sensor s response bandwidth and amplitude, allowing detection of the reaction without having the reactants in physical contact with the sensor.

  10. Equivalent circuit of a composite acoustic resonator for microwave radioelectronic devices

    NASA Astrophysics Data System (ADS)

    Mansfel'D, G. D.; Alekseev, S. G.; Polzikova, N. I.

    2008-07-01

    On the basis of analyzing the expression for the input electric impedance of a composite microwave acoustic resonator, its equivalent electric circuit is constructed. It is shown that, for high-order harmonics, the difference between the antiresonance and resonance frequencies is determined not only by the electromechanical coupling coefficient, but also by the loss in the structure. The conditions under which this difference corresponds to the bandwidth of the equivalent parallel electric oscillatory circuit are formulated. Expressions for the resonance and antiresonance frequencies are derived. The procedures of determining the Q factor and the electromechanical coupling coefficient from the measured resonance and antiresonance frequencies of the structure are justified.

  11. Accessible magnetic resonance imaging.

    PubMed

    Kaufman, L; Arakawa, M; Hale, J; Rothschild, P; Carlson, J; Hake, K; Kramer, D; Lu, W; Van Heteren, J

    1989-10-01

    The cost of magnetic resonance imaging (MRI) is driven by magnetic field strength. Misperceptions as to the impact of field strength on performance have led to systems that are more expensive than they need to be. Careful analysis of all the factors that affect diagnostic quality lead to the conclusion that field strength per se is not a strong determinant of system performance. Freed from the constraints imposed by high-field operation, it is possible to exploit a varied set of opportunities afforded by low-field operation. In addition to lower costs and easier siting, we can take advantage of shortened T1 times, higher contrast, reduced sensitivity to motion, and reduced radiofrequency power deposition. These conceptual advantages can be made to coalesce onto practical imaging systems. We describe a low-cost MRI system that utilizes a permanent magnet of open design. Careful optimization of receiving antennas and acquisition sequences permit performance levels consistent with those needed for an effective diagnostic unit. Ancillary advantages include easy access to the patient, reduced claustrophobia, quiet and comfortable operation, and absence of a missile effect. The system can be sited in 350 sq ft and consumes a modest amount of electricity. MRI equipment of this kind can widen the population base than can access this powerful and beneficial diagnostic modality. PMID:2640910

  12. Neutron resonance averaging

    SciTech Connect

    Chrien, R.E.

    1986-10-01

    The principles of resonance averaging as applied to neutron capture reactions are described. Several illustrations of resonance averaging to problems of nuclear structure and the distribution of radiative strength in nuclei are provided. 30 refs., 12 figs.

  13. Nanomechanical resonance detector

    DOEpatents

    Grossman, Jeffrey C; Zettl, Alexander K

    2013-10-29

    An embodiment of a nanomechanical frequency detector includes a support structure and a plurality of elongated nanostructures coupled to the support structure. Each of the elongated nanostructures has a particular resonant frequency. The plurality of elongated nanostructures has a range of resonant frequencies. An embodiment of a method of identifying an object includes introducing the object to the nanomechanical resonance detector. A resonant response by at least one of the elongated nanostructures of the nanomechanical resonance detector indicates a vibrational mode of the object. An embodiment of a method of identifying a molecular species of the present invention includes introducing the molecular species to the nanomechanical resonance detector. A resonant response by at least one of the elongated nanostructures of the nanomechanical resonance detector indicates a vibrational mode of the molecular species.

  14. Mars Subsurface Exploration Using Schumann Resonance

    NASA Astrophysics Data System (ADS)

    Kozakiewicz, Joanna; Kulak, Andrzej; Mlynarczyk, Janusz

    2014-05-01

    In a planetary environment, an electrically conductive ionosphere and ground create a spherical electromagnetic cavity. In this cavity, extremely low frequency (ELF, 3-3000 Hz) electromagnetic waves are weakly attenuated and can propagate around the globe producing global resonance. The extremely low frequency waves are generated by electrical discharges in planetary atmospheres. We have developed an analytical method that enables taking into account not only the electrical properties of the Martian ionosphere but also the Martian ground. This method allowed us to obtain the Schumann resonance frequencies and Q factors and analyze how they depend on the Martian environmental properties. We compared the results from our analytical model with previously published results from numerical modeling. In this work, we show that the Martian ground has a significant influence on the Schumann resonance parameters. Therefore, Schumann resonance can be used us a tool to study, not only the properties of the Martian atmosphere, but also the properties of the subsurface layers. It can be particularly useful in groundwater exploration. In order to study the influence of water on the Schumann resonance parameters on Mars, we assumed two cases of the Martian ground containing aquifers. In both cases, we considered the upper part of the Martian crust composed of porous basaltic rocks containing ice. Beneath this layer, we implemented water-bearing basalts. We assumed that ice and water contains some NaCl impurities or solutions. In the first case, we considered the low concentration of salts in ice and low-salinity water. In the second case, we assumed some high-impurity ice and brines. In order to compare the results of the above-mentioned cases with a situation in which the subsurface of Mars does not contain any water, we introduced the model of the Martian crust composed only of dry basaltic rocks. There are clear differences in the Schumann resonance parameters for the different

  15. Miniature Sapphire Acoustic Resonator - MSAR

    NASA Technical Reports Server (NTRS)

    Wang, Rabi T.; Tjoelker, Robert L.

    2011-01-01

    A room temperature sapphire acoustics resonator incorporated into an oscillator represents a possible opportunity to improve on quartz ultrastable oscillator (USO) performance, which has been a staple for NASA missions since the inception of spaceflight. Where quartz technology is very mature and shows a performance improvement of perhaps 1 dB/decade, these sapphire acoustic resonators when integrated with matured quartz electronics could achieve a frequency stability improvement of 10 dB or more. As quartz oscillators are an essential element of nearly all types of frequency standards and reference systems, the success of MSAR would advance the development of frequency standards and systems for both groundbased and flight-based projects. Current quartz oscillator technology is limited by quartz mechanical Q. With a possible improvement of more than x 10 Q with sapphire acoustic modes, the stability limit of current quartz oscillators may be improved tenfold, to 10(exp -14) at 1 second. The electromagnetic modes of sapphire that were previously developed at JPL require cryogenic temperatures to achieve the high Q levels needed to achieve this stability level. However sapphire fs acoustic modes, which have not been used before in a high-stability oscillator, indicate the required Q values (as high as Q = 10(exp 8)) may be achieved at room temperature in the kHz range. Even though sapphire is not piezoelectric, such a high Q should allow electrostatic excitation of the acoustic modes with a combination of DC and AC voltages across a small sapphire disk (approximately equal to l mm thick). The first evaluations under this task will test predictions of an estimated input impedance of 10 kilohms at Q = 10(exp 8), and explore the Q values that can be realized in a smaller resonator, which has not been previously tested for acoustic modes. This initial Q measurement and excitation demonstration can be viewed similar to a transducer converting electrical energy to

  16. Spin wave resonance detection using magnetic tunnel junction structure

    NASA Astrophysics Data System (ADS)

    Bi, Chong; Fan, Xin; Pan, Liqing; Kou, Xiaoming; Wu, Jun; Yang, Qinghui; Zhang, Huaiwu; Xiao, John Q.

    2011-11-01

    We have demonstrated that spin wave resonance in a permalloy microstrip can be detected by an electrical method based on magnetic tunnel junction structures. The detection method promises high spatial resolution and sensitivity. Both even and odd spin wave resonance modes can be clearly observed in a permalloy microstrip. The spin wave induced voltage is proportional to the input microwave power at each resonance mode. Data analysis using the model of quantized dipole-exchange spin wave resonance suggests the edge pinning of spin wave sensitively depends on the order of the spin wave mode, as well as on the excitation frequency for modes of the higher order.

  17. An Inexpensive Resonance Demonstration

    ERIC Educational Resources Information Center

    Dukes, Phillip

    2005-01-01

    The phenomenon of resonance is applicable to almost every branch of physics. Without resonance, there wouldn't be televisions or stereos, or even swings on the playground. However, resonance also has undesirable side effects such as irritating noises in the car and the catastrophic events such as helicopters flying apart. In this article, the…

  18. Magnetic Resonance Imaging (MRI)

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? Magnetic Resonance Imaging (MRI) KidsHealth > For Teens > Magnetic Resonance Imaging (MRI) Print A A A Text Size What's ... Exam Safety Getting Your Results What Is MRI? Magnetic resonance imaging (MRI) is a type of safe, painless testing ...

  19. Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Andrew, E. R.

    2009-06-01

    Author's preface; 1. Introduction; 2. Basic theory; 3. Experimental methods; 4. Measurement of nuclear properties and general physical applications; 5. Nuclear magnetic resonance in liquids and gases; 6. Nuclear magnetic resonance in non-metallic solids; 7. Nuclear magnetic resonance in metals; 8. Quadrupole effects; Appendices 1-6; Glossary of symbols; Bibliography and author index; Subject index.

  20. Atomic motion of resonantly vibrating quartz crystal visualized by time-resolved X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Aoyagi, Shinobu; Osawa, Hitoshi; Sugimoto, Kunihisa; Fujiwara, Akihiko; Takeda, Shoichi; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2015-11-01

    Transient atomic displacements during a resonant thickness-shear vibration of AT-cut α-quartz are revealed by time-resolved X-ray diffraction under an alternating electric field. The lattice strain resonantly amplified by the alternating electric field is ˜104 times larger than that induced by a static electric field. The resonantly amplified lattice strain is achieved by fast displacements of oxygen anions and collateral resilient deformation of Si-O-Si angles bridging rigid SiO4 tetrahedra, which efficiently transduce electric energy into elastic energy.

  1. Atomic motion of resonantly vibrating quartz crystal visualized by time-resolved X-ray diffraction

    SciTech Connect

    Aoyagi, Shinobu; Osawa, Hitoshi; Sugimoto, Kunihisa; Fujiwara, Akihiko

    2015-11-16

    Transient atomic displacements during a resonant thickness-shear vibration of AT-cut α-quartz are revealed by time-resolved X-ray diffraction under an alternating electric field. The lattice strain resonantly amplified by the alternating electric field is ∼10{sup 4} times larger than that induced by a static electric field. The resonantly amplified lattice strain is achieved by fast displacements of oxygen anions and collateral resilient deformation of Si−O−Si angles bridging rigid SiO{sub 4} tetrahedra, which efficiently transduce electric energy into elastic energy.

  2. Electrical stator

    DOEpatents

    Fanning, Alan W.; Olich, Eugene E.

    1994-01-01

    An electrical stator of an electromagnetic pump includes first and second spaced apart coils each having input and output terminals for carrying electrical current. An elongate electrical connector extends between the first and second coils and has first and second opposite ends. The connector ends include respective slots receiving therein respective ones of the coil terminals to define respective first and second joints. Each of the joints includes a braze filler fixedly joining the connector ends to the respective coil terminals for carrying electrical current therethrough.

  3. Voltage-dependent ferromagnetic resonance in epitaxial multiferroic nanocomposites

    NASA Astrophysics Data System (ADS)

    Benatmane, Nadjib; Crane, S. P.; Zavaliche, F.; Ramesh, R.; Clinton, T. W.

    2010-02-01

    We demonstrate electrical control of the ferromagnetic resonance (FMR) in multiferroic nanostructures. A series of heteroepitaxial BiFeO3-NiFe2O4 nanocomposites of varying thickness are characterized using a microwave probe with magnetic and electric sensitivity. We apply an electric field to a sample and observe voltage-driven shifts in the FMR frequency, reflecting a change in magnetic anisotropy. The voltage dependence of the FMR linewidths is even more pronounced, indicating the electric polarization can induce relatively large magnetic nonuniformity in the material. These characteristics may lead to a class of rf filters where both frequency and bandwidth are electrically tunable.

  4. Ovenized microelectromechanical system (MEMS) resonator

    SciTech Connect

    Olsson, Roy H; Wojciechowski, Kenneth; Kim, Bongsang

    2014-03-11

    An ovenized micro-electro-mechanical system (MEMS) resonator including: a substantially thermally isolated mechanical resonator cavity; a mechanical oscillator coupled to the mechanical resonator cavity; and a heating element formed on the mechanical resonator cavity.

  5. Mechanically tolerant fluidic split ring resonators

    NASA Astrophysics Data System (ADS)

    Awang, Robiatun A.; Baum, Thomas; Nasabi, Mahyar; Sriram, Sharath; Rowe, Wayne S. T.

    2016-07-01

    Flexible resonators are crucial elements for non-planar, conformal and curved or movable surfaces in flexible high frequency electronic environments. Here, we demonstrate a stretchable, bendable, twistable and reversibly deformable split ring resonator (SRR) operating at ∼3 GHz. The mechanical and electrical performance of the SRR was achieved by encapsulating liquid metal (galinstan) in a microfluidic channel of highly elastic polydimethylsiloxane. Applying mechanical deformation (bending, stretching and twisting) to the SRR results in minimal deviation of the transmission response. This offers a stable and predictable response for flexible electronic applications where mechanical deformation or conformity is inherent.

  6. Optical Helmholtz resonators

    NASA Astrophysics Data System (ADS)

    Chevalier, Paul; Bouchon, Patrick; Haïdar, Riad; Pardo, Fabrice

    2014-08-01

    Helmholtz resonators are widely used acoustic components able to select a single frequency. Here, based on an analogy between acoustics and electromagnetism wave equations, we present an electromagnetic 2D Helmholtz resonator made of a metallic slit-box structure. At the resonance, the light is funneled in the λ/800 apertures, and is subsequently absorbed in the cavity. As in acoustics, there is no higher order of resonance, which is an appealing feature for applications such as photodetection or thermal emission. Eventually, we demonstrate that the slit is of capacitive nature while the box behaves inductively. We derive an analytical formula for the resonance wavelength, which does not rely on wave propagation and therefore does not depend on the permittivity of the material filling the box. Besides, in contrast with half-wavelength resonators, the resonance wavelength can be engineered by both the slit aspect ratio and the box area.

  7. Magnetic resonance energy and topological resonance energy.

    PubMed

    Aihara, Jun-Ichi

    2016-04-28

    Ring-current diamagnetism of a polycyclic π-system is closely associated with thermodynamic stability due to the individual circuits. Magnetic resonance energy (MRE), derived from the ring-current diamagnetic susceptibility, was explored in conjunction with graph-theoretically defined topological resonance energy (TRE). For many aromatic molecules, MRE is highly correlative with TRE with a correlation coefficient of 0.996. For all π-systems studied, MRE has the same sign as TRE. The only trouble with MRE may be that some antiaromatic and non-alternant species exhibit unusually large MRE-to-TRE ratios. This kind of difficulty can in principle be overcome by prior geometry-optimisation or by changing spin multiplicity. Apart from the semi-empirical resonance-theory resonance energy, MRE is considered as the first aromatic stabilisation energy (ASE) defined without referring to any hypothetical polyene reference. PMID:26878709

  8. Resonance splitting in gyrotropic ring resonators.

    PubMed

    Jalas, Dirk; Petrov, Alexander; Krause, Michael; Hampe, Jan; Eich, Manfred

    2010-10-15

    We present the theoretical concept of an optical isolator based on resonance splitting in a silicon ring resonator covered with a magneto-optical polymer cladding. For this task, a perturbation method is derived for the modes in the cylindrical coordinate system. A polymer magneto-optical cladding causing a 0.01 amplitude of the off-diagonal element of the dielectric tensor is assumed. It is shown that the derived resonance splitting of the clockwise and counterclockwise modes increases for smaller ring radii. For the ring with a radius of approximately 1.5μm, a 29GHz splitting is demonstrated. An integrated optical isolator with a 10μm geometrical footprint is proposed based on a critically coupled ring resonator. PMID:20967092

  9. Electric avenues

    SciTech Connect

    Stone, P.; Chang, A.

    1994-12-31

    Highly efficient electric drive technology developed originally for defense applications is being applied to the development of all electric shuttle buses for the San Jose International Airport. An innovative opportunity charging system using induction chargers will be incorporated to extend operation hours. The project, if successful, is expected to reduce pollution at the airport and generate jobs for displaced defense workers.

  10. Electric machine

    DOEpatents

    El-Refaie, Ayman Mohamed Fawzi; Reddy, Patel Bhageerath

    2012-07-17

    An interior permanent magnet electric machine is disclosed. The interior permanent magnet electric machine comprises a rotor comprising a plurality of radially placed magnets each having a proximal end and a distal end, wherein each magnet comprises a plurality of magnetic segments and at least one magnetic segment towards the distal end comprises a high resistivity magnetic material.

  11. A circuit model for the hybrid resonance modes of paired SRR metamaterials.

    PubMed

    Poo, Yin; Wu, Rui-xin; Liu, Min; Wang, Ling

    2014-01-27

    To better understand the resonance modes caused by the interelement couplings in the building block of metamaterials, we propose a circuit model for the hybrid resonance modes of paired split ring resonators. The model identifies the electromagnetic coupling between the paired rings by electric and magnetic coupling networks and well explains the variation of hybrid resonance modes with respect to the distance and the twist angle between the rings. The predictions of our model are further proved by experiments. PMID:24515201

  12. Plasmon coupling of magnetic resonances in an asymmetric gold semishell

    NASA Astrophysics Data System (ADS)

    Ye, Jian; Kong, Yan; Liu, Cheng

    2016-05-01

    The generation of magnetic dipole resonances in metallic nanostructures is of great importance for constructing near-zero or even negative refractive index metamaterials. Commonly, planar two-dimensional (2D) split-ring resonators or relevant structures are basic elements of metamaterials. In this work, we introduce a three-dimensional (3D) asymmetric Au semishell composed of two nanocups with a face-to-face geometry and demonstrate two distinct magnetic resonances spontaneously in the visible–near infrared optical wavelength regime. These two magnetic resonances are from constructive and destructive hybridization of magnetic dipoles of individual nanocups in the asymmetric semishell. In contrast, complete cancellation of magnetic dipoles in the symmetric semishell leads to only a pronounced electric mode with near-zero magnetic dipole moment. These 3D asymmetric resonators provide new ways for engineering hybrid resonant modes and ultra-high near-field enhancement for the design of 3D metamaterials.

  13. Piezoelectric resonator assembly with thin molybdenum mounting clips

    DOEpatents

    Peters, R. Donald

    1981-01-01

    A resonator mounting assembly wherein the resonator blank is mounted agai an essentially planar surface presented by a plurality of peripherally disposed mounting clips and bonded to this surface to provide substantially all the mechanical support for the blank in a direction normal to the major faces of the resonator blank, while being flexible in the directions parallel to said major faces so as to minimize radial stresses on the resonator blank, particularly during thermal cycling of the resonator assembly. The clips are fabricated of a low thermal expansion material, such as molybdenum, which also has considerable yield strength after exposure to processing temperatures; the bonding of the clips to the edges of the resonator blank can be achieved by a polyimide containing electrically conductive particles.

  14. Electrical Properties of (Ba, Sr)TiO3 Films on Ru Bottom Electrodes Prepared by Electron Cyclotron Resonance Plasma Chemical Vapor Deposition at Extremely Low Temperature and Rapid Thermal Annealing

    NASA Astrophysics Data System (ADS)

    Sone, Shuji; Akahane, Reiko; Arita, Koji; Yabuta, Hisato; Yamamichi, Shintaro; Yoshida, Masaji; Kato, Yoshitake

    1999-04-01

    (Ba, Sr)TiO3 (BST) films were prepared on Ru bottom electrodes by electron cyclotron resonance chemical vapor deposition at extremely low temperature and rapid thermal annealing (RTA). Leakage current characteristics were improved by lowering the BST deposition temperature down to 120°C. (Ba+Sr)-rich films with a (Ba+Sr)/Ti ratio of 1.1 1.5 had lower leakage current densities than stoichiometric and Ti-rich films with a ratio of 0.8 0.9. Cross sectional transmission electron microscopy observations showed that the 120°C-deposited and 700°C-RTA-treated (Ba+Sr)-rich film had a granular structure and smooth interfaces with the electrodes. The stoichiometric and Ti-rich films had columnar structures and larger interface roughness. As a result, low leakage current density less than 10-7 A/cm2 at ±1 V were obtained for 30 nm-thick BST films with a (Ba+Sr)/Ti ratio of 1.1 1.5 by combination of 120°C deposition and 700°C RTA.

  15. 11th International Conference on Atmospheric Electricity

    NASA Technical Reports Server (NTRS)

    Christian, H. J. (Compiler)

    1999-01-01

    This document contains the proceedings from the 11th International Conference on Atmospheric Electricity (ICAE 99), held June 7-11, 1999. This conference was attended by scientists and researchers from around the world. The subjects covered included natural and artificially initiated lightning, lightning in the middle and upper atmosphere (sprites and jets), lightning protection and safety, lightning detection techniques (ground, airborne, and space-based), storm physics, electric fields near and within thunderstorms, storm electrification, atmospheric ions and chemistry, shumann resonances, satellite observations of lightning, global electrical processes, fair weather electricity, and instrumentation.

  16. Electric moped

    SciTech Connect

    Ferschl, M.S.

    1981-02-26

    Two electrically powered mopeds were designed and built. These vehicles offer single-person transportation which is convenient, quiet, low-cost, smooth, and pollution-free. The first moped has a 12 volt electrical system. The second has a 24 volt electrical system. They both have top speeds of about 20 miles per hour. They both use transistorized speed controls and deep-discharge, lead-acid batteries. These mopeds were put through a 750 mile test program. In this program, the 12 volt bike had an average range of nine miles. The 24 volt bike, with a smaller battery capacity, had an average range of six miles.

  17. Electrical connector

    DOEpatents

    Dilliner, Jennifer L.; Baker, Thomas M.; Akasam, Sivaprasad; Hoff, Brian D.

    2006-11-21

    An electrical connector includes a female component having one or more receptacles, a first test receptacle, and a second test receptacle. The electrical connector also includes a male component having one or more terminals configured to engage the one or more receptacles, a first test pin configured to engage the first test receptacle, and a second test pin configured to engage the second test receptacle. The first test receptacle is electrically connected to the second test receptacle, and at least one of the first test pin and the second test pin is shorter in length than the one or more terminals.

  18. Stochastic resonance in mammalian neuronal networks

    SciTech Connect

    Gluckman, B.J.; So, P.; Netoff, T.I.; Spano, M.L.; Schiff, S.J. |

    1998-09-01

    We present stochastic resonance observed in the dynamics of neuronal networks from mammalian brain. Both sinusoidal signals and random noise were superimposed into an applied electric field. As the amplitude of the noise component was increased, an optimization (increase then decrease) in the signal-to-noise ratio of the network response to the sinusoidal signal was observed. The relationship between the measures used to characterize the dynamics is discussed. Finally, a computational model of these neuronal networks that includes the neuronal interactions with the electric field is presented to illustrate the physics behind the essential features of the experiment. {copyright} {ital 1998 American Institute of Physics.}

  19. Excitation and tuning of Fano-like cavity plasmon resonances in dielectric-metal core-shell resonators

    NASA Astrophysics Data System (ADS)

    Gu, Ping; Wan, Mingjie; Wu, Wenyang; Chen, Zhuo; Wang, Zhenlin

    2016-05-01

    Fano resonances have been realized in plasmonic systems and have found intriguing applications, in which, however, precisely controlled symmetry breaking or particular arrangement of multiple constituents is usually involved. Although simple core-shell type architectures composed of a spherical dielectric core and a concentric metallic shell layer have been proposed as good candidates that support inherent Fano resonances, these theoretical predictions have rarely seen any detailed experimental investigation. Here, we report on the experimental investigation of the magnetic and electric-based multipolar plasmonic Fano resonances in the dielectric-metal core-shell resonators that are formed by wrapping a nearly perfect metal shell layer around a dielectric sphere. We demonstrate that these Fano resonances originate from the interference between the Mie cavity and sphere plasmon resonances. Moreover, we present that the variation on either the dielectric core size or core refractive index allows for easily tuning the observed Fano resonances over a wide spectral range. Our findings are supported by excellent agreement with analytical calculations, and offer unprecedented opportunities for realizing ultrasensitive bio-sensors, lasing and nonlinear optical devices.Fano resonances have been realized in plasmonic systems and have found intriguing applications, in which, however, precisely controlled symmetry breaking or particular arrangement of multiple constituents is usually involved. Although simple core-shell type architectures composed of a spherical dielectric core and a concentric metallic shell layer have been proposed as good candidates that support inherent Fano resonances, these theoretical predictions have rarely seen any detailed experimental investigation. Here, we report on the experimental investigation of the magnetic and electric-based multipolar plasmonic Fano resonances in the dielectric-metal core-shell resonators that are formed by wrapping a

  20. Excitonic surface lattice resonances

    NASA Astrophysics Data System (ADS)

    Humphrey, A. D.; Gentile, M. J.; Barnes, W. L.

    2016-08-01

    Electromagnetic resonances are important in controlling light at the nanoscale. The most studied such resonance is the surface plasmon resonance that is associated with metallic nanostructures. Here we explore an alternative resonance, the surface exciton-polariton resonance, one based on excitonic molecular materials. Our study is based on analytical and numerical modelling. We show that periodic arrays of suitable molecular nanoparticles may support surface lattice resonances that arise as a result of coherent interactions between the particles. Our results demonstrate that excitonic molecular materials are an interesting alternative to metals for nanophotonics; they offer the prospect of both fabrication based on supramolecular chemistry and optical functionality arising from the way the properties of such materials may be controlled with light.

  1. Enhancement of artificial magnetism via resonant bianisotropy.

    PubMed

    Markovich, Dmitry; Baryshnikova, Kseniia; Shalin, Alexander; Samusev, Anton; Krasnok, Alexander; Belov, Pavel; Ginzburg, Pavel

    2016-01-01

    All-dielectric "magnetic light" nanophotonics based on high refractive index nanoparticles allows controlling magnetic component of light at nanoscale without having high dissipative losses. The artificial magnetic optical response of such nanoparticles originates from circular displacement currents excited inside those structures and strongly depends on geometry and dispersion of optical materials. Here an approach for enhancing of magnetic response via resonant bianisotropy effect is proposed and analyzed. The key mechanism of enhancement is based on electric-magnetic interaction between two electrically and magnetically resonant nanoparticles of all-dielectric dimer. It was shown that proper geometrical arrangement of the dimer in respect to the incident illumination direction allows flexible control over all vectorial components of the magnetic moment, tailoring the latter in the dynamical range of 100% and delivering enhancement up to 36% relative to performances of standalone spherical particles. The proposed approach provides pathways for designs of all-dielectric metamaterials and metasurfaces with strong magnetic responses. PMID:26941126

  2. Enhancement of artificial magnetism via resonant bianisotropy

    NASA Astrophysics Data System (ADS)

    Markovich, Dmitry; Baryshnikova, Kseniia; Shalin, Alexander; Samusev, Anton; Krasnok, Alexander; Belov, Pavel; Ginzburg, Pavel

    2016-03-01

    All-dielectric “magnetic light” nanophotonics based on high refractive index nanoparticles allows controlling magnetic component of light at nanoscale without having high dissipative losses. The artificial magnetic optical response of such nanoparticles originates from circular displacement currents excited inside those structures and strongly depends on geometry and dispersion of optical materials. Here an approach for enhancing of magnetic response via resonant bianisotropy effect is proposed and analyzed. The key mechanism of enhancement is based on electric-magnetic interaction between two electrically and magnetically resonant nanoparticles of all-dielectric dimer. It was shown that proper geometrical arrangement of the dimer in respect to the incident illumination direction allows flexible control over all vectorial components of the magnetic moment, tailoring the latter in the dynamical range of 100% and delivering enhancement up to 36% relative to performances of standalone spherical particles. The proposed approach provides pathways for designs of all-dielectric metamaterials and metasurfaces with strong magnetic responses.

  3. Large mode radius resonators

    NASA Technical Reports Server (NTRS)

    Harris, Michael R.

    1987-01-01

    Resonator configurations permitting operation with large mode radius while maintaining good transverse mode discrimination are considered. Stable resonators incorporating an intracavity telescope and unstable resonator geometries utilizing an output coupler with a Gaussian reflectivity profile are shown to enable large radius single mode laser operation. Results of heterodyne studies of pulsed CO2 lasers with large (11mm e sup-2 radius) fundamental mode sizes are presented demonstrating minimal frequency sweeping in accordance with the theory of laser-induced medium perturbations.

  4. Acoustic wave flow sensor using quartz thickness shear mode resonator.

    PubMed

    Qin, Lifeng; Zeng, Zijing; Cheng, Hongbin; Wang, Qing-Ming

    2009-09-01

    A quartz thickness shear mode (TSM) bulk acoustic wave resonator was used for in situ and real-time detection of liquid flow rate in this study. A special flow chamber made of 2 parallel acrylic plates was designed for flow measurement. The flow chamber has a rectangular flow channel, 2 flow reservoirs for stabilizing the fluid flow, a sensor mounting port for resonator holding, one inlet port, and one outlet port for pipe connection. A 5-MHz TSM quartz resonator was edge-bonded to the sensor mounting port with one side exposed to the flowing liquid and other side exposed to air. The electrical impedance spectra of the quartz resonator at different volumetric flow rate conditions were measured by an impedance analyzer for the extraction of the resonant frequency through a data-fitting method. The fundamental, 3rd, 5th, 7th, and 9th resonant frequency shifts were found to be around 920, 3572, 5947, 8228, and 10,300 Hz for flow rate variation from 0 to 3000 mL/min, which had a corresponding Reynolds number change from 0 to 822. The resonant frequency shifts of different modes are found to be quadratic with flow rate, which is attributed to the nonlinear effect of quartz resonator due to the effective normal pressure imposing on the resonator sensor by the flowing fluid. The results indicate that quartz TSM resonators can be used for flow sensors with characteristics of simplicity, fast response, and good repeatability. PMID:19811997

  5. Electrical Conductivity.

    ERIC Educational Resources Information Center

    Allen, Philip B.

    1979-01-01

    Examines Drude's classical (1900) theory of electrical conduction, details the objections to and successes of the 1900 theory, and investigates the Quantum (1928) theory of conduction, reviewing its successes and limitations. (BT)

  6. Electrical injury

    MedlinePlus

    ... wiring Flashing of electric arcs from high-voltage power lines Lightning Machinery or occupational-related exposures Young ... a passenger in a vehicle struck by a power line, remain in it until help arrives unless ...

  7. Electrical Conductivity.

    ERIC Educational Resources Information Center

    Hershey, David R.; Sand, Susan

    1993-01-01

    Explains how electrical conductivity (EC) can be used to measure ion concentration in solutions. Describes instrumentation for the measurement, temperature dependence and EC, and the EC of common substances. (PR)

  8. Error analysis of quartz crystal resonator applications

    SciTech Connect

    Lucklum, R.; Behling, C.; Hauptmann, P.; Cernosek, R.W.; Martin, S.J.

    1996-12-31

    Quartz crystal resonators in chemical sensing applications are usually configured as the frequency determining element of an electrical oscillator. By contrast, the shear modulus determination of a polymer coating needs a complete impedance analysis. The first part of this contribution reports the error made if common approximations are used to relate the frequency shift to the sorbed mass. In the second part the authors discuss different error sources in the procedure to determine shear parameters.

  9. Internal resonance for nonlinear vibration energy harvesting

    NASA Astrophysics Data System (ADS)

    Cao, D. X.; Leadenham, S.; Erturk, A.

    2015-11-01

    The transformation of waste vibration energy into low-power electricity has been heavily researched over the last decade to enable self-sustained wireless electronic components. Monostable and bistable nonlinear oscillators have been explored by several research groups in an effort to enhance the frequency bandwidth of operation. Linear two-degree-of-freedom (2-DOF) configurations as well as the combination of a nonlinear single-DOF harvester with a linear oscillator to constitute a nonlinear 2-DOF harvester have also been explored to develop broadband energy harvesters. In the present work, the concept of nonlinear internal resonance in a continuous frame structure is explored for broadband energy harvesting. The L-shaped beam-mass structure with quadratic nonlinearity was formerly studied in the nonlinear dynamics literature to demonstrate modal energy exchange and the saturation phenomenon when carefully tuned for two-to-one internal resonance. In the current effort, piezoelectric coupling and an electrical load are introduced, and electromechanical equations of the L-shaped energy harvester are employed to explore primary resonance behaviors around the first and the second linear natural frequencies for bandwidth enhancement. Simulations using approximate analytical frequency response equations as well as numerical solutions reveal significant bandwidth enhancement as compared to a typical linear 2-DOF counterpart. Vibration and voltage responses are explored, and the effects of various system parameters on the overall dynamics of the internal resonance-based energy harvesting system are reported.

  10. Electric generator

    DOEpatents

    Foster, Jr., John S.; Wilson, James R.; McDonald, Jr., Charles A.

    1983-01-01

    1. In an electrical energy generator, the combination comprising a first elongated annular electrical current conductor having at least one bare surface extending longitudinally and facing radially inwards therein, a second elongated annular electrical current conductor disposed coaxially within said first conductor and having an outer bare surface area extending longitudinally and facing said bare surface of said first conductor, the contiguous coaxial areas of said first and second conductors defining an inductive element, means for applying an electrical current to at least one of said conductors for generating a magnetic field encompassing said inductive element, and explosive charge means disposed concentrically with respect to said conductors including at least the area of said inductive element, said explosive charge means including means disposed to initiate an explosive wave front in said explosive advancing longitudinally along said inductive element, said wave front being effective to progressively deform at least one of said conductors to bring said bare surfaces thereof into electrically conductive contact to progressively reduce the inductance of the inductive element defined by said conductors and transferring explosive energy to said magnetic field effective to generate an electrical potential between undeformed portions of said conductors ahead of said explosive wave front.

  11. Reflections on Electric Probes

    NASA Astrophysics Data System (ADS)

    Braithwaite, Nicholas

    2007-10-01

    One of the more immediate temptations for an experimental plasma physicist is to insert some kind of refractory, conducting material into a plasma, as a simple means of probing its charge composition. Irvine Langmuir tried it in the 1920s and was one of the first to develop an electrical probe method in his early work on electrical discharge plasmas. There are now numerous variations on the theme including planar, cylindrical and spherical geometry with single, double and triple probes. There are also probes that resonate, propagate and reciprocate. Some probes are electrostatic and others are electromagnetic; some are effectively wireless; most absorb but some emit. All types can be used in steady and transient plasmas, while special schemes have been devised for RF plasmas, using passive and active compensation. Magnetised plasmas pose further challenges. Each configuration is accompanied by assumptions that constrain both their applicability and the analytical methods that translate the measured currents and voltages variously into charge densities, space potentials, particle fluxes, energy distributions and measures of collisionality. This talk will take a broad look at the options and opportunities for electric probes, principally in the environment of non-equilibrium plasma.

  12. Electrical conductivity, differential scanning calorimetry, X-ray diffraction, and 7Li nuclear magnetic resonance studies of n-C x H(2 x+1)OSO3Li ( x = 12, 14, 16, 18, and 20)

    NASA Astrophysics Data System (ADS)

    Hirakawa, Satoru; Morimoto, Yoshiaki; Honda, Hisashi

    2015-04-01

    Electrical conductivity ( σ), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) measurements of n-C x H (2 x+1) OSO 3Li ( x= 12, 14, 16, 18, and 20) crystals were performed as a function of temperature. In addition, σ, DSC, and XRD observations of n-C x H (2 x+1) OSO 3Na and n-C x H (2 x+1) OSO 3K ( x= 12, 14, 16, 18, and 20) crystals were carried out for comparison. DSC results of the salts revealed several solid-solid phase transitions with large entropy changes (Δ S). For n-C 18 H 37 OSO 3Li and n-C 20 H 41 OSO 3Li salts, each melting point produced a small Δ S mp value compared with the total entropy change in the solid phases (Δ S tr1+Δ S tr2). Additionally, Li + ion diffusion was detected in the highest temperature solid phases. For K salts, larger σ values were detected for potassium alkylsulfates compared with those reported for alkyl carboxylate. 7Li NMR spectra of n-C 18 H 37 OSO 3Li crystals recorded in the low-temperature phase showed large asymmetry parameters, suggesting the Li + ions are localized at asymmetric sites in the crystals.

  13. Three-dimensional THz lumped-circuit resonators.

    PubMed

    Todorov, Yanko; Desfond, Pascal; Belacel, Cherif; Becerra, Loïc; Sirtori, Carlo

    2015-06-29

    Our work describes a novel three dimensional meta-material resonator design for optoelectronic applications in the THz spectral range. In our resonant circuits, the capacitors are formed by double-metal regions cladding a dielectric core. Unlike conventional planar metamaterials, the electric field is perpendicular to the surface and totally confined in the dielectric core. Furthermore, the magnetic field, confined in the inductive part, is parallel to the electric field, ruling out coupling through propagation effects. Our geometry thus combines the benefit of double-metal structures that provide parallel plate capacitors, while maintaining the ability of meta-material resonators to adjust independently the capacitive and inductive parts. Furthermore, in our geometry, a constant bias can be applied across the dielectric, making these resonators very suitable for applications such as ultra-low dark current THz quantum detectors and amplifiers based on quantum cascade gain medium. PMID:26191695

  14. Ultra-sharp plasmonic resonances from monopole optical nanoantenna phased arrays

    SciTech Connect

    Li, Shi-Qiang; Bruce Buchholz, D.; Zhou, Wei; Ketterson, John B.; Ocola, Leonidas E.; Sakoda, Kazuaki; Chang, Robert P. H.

    2014-06-09

    Diffractively coupled plasmonic resonances possess both ultra-sharp linewidths and giant electric field enhancement around plasmonic nanostructures. They can be applied to create a new generation of sensors, detectors, and nano-optical devices. However, all current designs require stringent index-matching at the resonance condition that limits their applicability. Here, we propose and demonstrate that it is possible to relieve the index-matching requirement and to induce ultra-sharp plasmon resonances in an ordered vertically aligned optical nano-antenna phased array by transforming a dipole resonance to a monopole resonance with a mirror plane. Due to the mirror image effect, the monopole resonance not only retained the dipole features but also enhanced them. The engineered resonances strongly suppressed the radiative decay channel, resulting in a four-order of magnitude enhancement in local electric field and a Q-factor greater than 200.

  15. Ultra-sharp plasmonic resonances from monopole optical nanoantenna phased arrays

    NASA Astrophysics Data System (ADS)

    Li, Shi-Qiang; Zhou, Wei; Bruce Buchholz, D.; Ketterson, John B.; Ocola, Leonidas E.; Sakoda, Kazuaki; Chang, Robert P. H.

    2014-06-01

    Diffractively coupled plasmonic resonances possess both ultra-sharp linewidths and giant electric field enhancement around plasmonic nanostructures. They can be applied to create a new generation of sensors, detectors, and nano-optical devices. However, all current designs require stringent index-matching at the resonance condition that limits their applicability. Here, we propose and demonstrate that it is possible to relieve the index-matching requirement and to induce ultra-sharp plasmon resonances in an ordered vertically aligned optical nano-antenna phased array by transforming a dipole resonance to a monopole resonance with a mirror plane. Due to the mirror image effect, the monopole resonance not only retained the dipole features but also enhanced them. The engineered resonances strongly suppressed the radiative decay channel, resulting in a four-order of magnitude enhancement in local electric field and a Q-factor greater than 200.

  16. Full counting statistics of quantum dot resonance fluorescence.

    PubMed

    Matthiesen, Clemens; Stanley, Megan J; Hugues, Maxime; Clarke, Edmund; Atatüre, Mete

    2014-01-01

    The electronic energy levels and optical transitions of a semiconductor quantum dot are subject to dynamics within the solid-state environment. In particular, fluctuating electric fields due to nearby charge traps or other quantum dots shift the transition frequencies via the Stark effect. The environment dynamics are mapped directly onto the fluorescence under resonant excitation and diminish the prospects of quantum dots as sources of indistinguishable photons in optical quantum computing. Here, we present an analysis of resonance fluorescence fluctuations based on photon counting statistics which captures the underlying time-averaged electric field fluctuations of the local environment. The measurement protocol avoids dynamic feedback on the electric environment and the dynamics of the quantum dot's nuclear spin bath by virtue of its resonant nature and by keeping experimental control parameters such as excitation frequency and external fields constant throughout. The method introduced here is experimentally undemanding. PMID:24810097

  17. Full counting statistics of quantum dot resonance fluorescence

    PubMed Central

    Matthiesen, Clemens; Stanley, Megan J.; Hugues, Maxime; Clarke, Edmund; Atatüre, Mete

    2014-01-01

    The electronic energy levels and optical transitions of a semiconductor quantum dot are subject to dynamics within the solid-state environment. In particular, fluctuating electric fields due to nearby charge traps or other quantum dots shift the transition frequencies via the Stark effect. The environment dynamics are mapped directly onto the fluorescence under resonant excitation and diminish the prospects of quantum dots as sources of indistinguishable photons in optical quantum computing. Here, we present an analysis of resonance fluorescence fluctuations based on photon counting statistics which captures the underlying time-averaged electric field fluctuations of the local environment. The measurement protocol avoids dynamic feedback on the electric environment and the dynamics of the quantum dot's nuclear spin bath by virtue of its resonant nature and by keeping experimental control parameters such as excitation frequency and external fields constant throughout. The method introduced here is experimentally undemanding. PMID:24810097

  18. The resonator handbook

    NASA Technical Reports Server (NTRS)

    Cook, Jerry D.; Zhou, Shiliang

    1993-01-01

    The purpose of this work is to extend resonator theory into the region in which the planar mirror is quite small. Results of the theoretical description are then extended to resonator design and experimental arrangements as discussed in further sections of this work. Finally, a discussion of dielectric measurements for small samples is included as a specific application of this work.

  19. Resonances in heavy systems

    SciTech Connect

    Betts, R.R.

    1983-01-01

    The experimental situation for the study of resonances in heavy-ion collisions is reviewed, with emphasis on the heaviest systems. New data are presented which show some of the systematics of this phenomenon. The narrow resonance structures are established as a feature of the nuclear structure of the composite system rather than a purely entrance channel effect.

  20. The Concept of Resonance

    ERIC Educational Resources Information Center

    Truhlar, Donald G.

    2007-01-01

    A general example of a delocalization system associated with a higher energy than the localized one, which suggests that it is wrong to consider delocalization as equivalent to resonance stabilization, is presented. The meaning of resonance energy as it appears in valence bond theory is described as the lowering of the calculated ground-state…

  1. Unstable optical resonators.

    PubMed

    Kahn, W K

    1966-03-01

    A technique, firmly based on a development from ray optics, is presented for calculating the loss due to the finite sizes of curved mirrors when these form an unstable optical resonator. If paraxial rays launched within such a resonator are confined near the resonator axis, the resonator is termed stable; otherwise it is termed unstable, and is known to have high losses. Siegman has recently presented a geometrical method, brilliantly constructed ad hoc, for calculating these losses in unstable resonators, and indicated where these might be advantageous in laser application. The ray optical theory presented here, which employs the concept of ray modes in an equivalent beam waveguide, is shown to yield results equivalent to those of Siegman for all cases considered by him. However, being derived from conventional ray optics, the validity of the formulas is independently established, and these formulas are immediately applicable to re-entrant resonators and resonators containing inhomogeneous media. The fractional loss per resonator pass is equal to 1-|lambda(2)|, where |lambda(2)| < this 1 is an eigenvalue of the transfer matrix T, representing the corresponding ray transformation. PMID:20048863

  2. Stochastic resonance in the mechanoelectrical transduction of hair cells

    NASA Astrophysics Data System (ADS)

    Lindner, John F.; Bennett, Matthew; Wiesenfeld, Kurt

    2005-11-01

    In transducing mechanical stimuli into electrical signals, at least some hair cells in vertebrate auditory and vestibular systems respond optimally to weak periodic signals at natural, nonzero noise intensities. We understand this stochastic resonance by constructing a faithful mechanical model reflecting the hair cell geometry and described by a nonlinear stochastic differential equation. This Langevin description elucidates the mechanism of hair cell stochastic resonance while supporting the hypothesis that noise plays a functional role in hearing.

  3. Resonant snubber inverter

    DOEpatents

    Lai, J.S.; Young, R.W. Sr.; Chen, D.; Scudiere, M.B.; Ott, G.W. Jr.; White, C.P.; McKeever, J.W.

    1997-06-24

    A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter. 14 figs.

  4. Narrowband resonant transmitter

    DOEpatents

    Hutchinson, Donald P.; Simpson, Marcus L.; Simpson, John T.

    2004-06-29

    A transverse-longitudinal integrated optical resonator (TLIR) is disclosed which includes a waveguide, a first and a second subwavelength resonant grating in the waveguide, and at least one photonic band gap resonant structure (PBG) in the waveguide. The PBG is positioned between the first and second subwavelength resonant gratings. An electro-optic waveguide material may be used to permit tuning the TLIR and to permit the TLIR to perform signal modulation and switching. The TLIR may be positioned on a bulk substrate die with one or more electronic and optical devices and may be communicably connected to the same. A method for fabricating a TLIR including fabricating a broadband reflective grating is disclosed. A method for tuning the TLIR's transmission resonance wavelength is also disclosed.

  5. Resonant snubber inverter

    DOEpatents

    Lai, Jih-Sheng; Young, Sr., Robert W.; Chen, Daoshen; Scudiere, Matthew B.; Ott, Jr., George W.; White, Clifford P.; McKeever, John W.

    1997-01-01

    A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter.

  6. Electromagnetic resonant modes of dielectric sphere bilayers

    SciTech Connect

    Andueza, A. Pérez-Conde, J.; Sevilla, J.

    2015-05-28

    Sphere bilayers have been proposed as promising structures for electromagnetic management in photonic crystal devices. These arrangements are made of two intertwined subsets of spheres of different size and refractive index, one subset filling the interstitial sites of the other. We present a systematic study of the electromagnetic resonant modes of the bilayers, in comparison with those of the constituent subsets of spheres. Three samples were built with glass and Teflon spheres and their transmission spectra measured in the microwave range (10–25 GHz). Simulations with finite integration time-domain method are in good agreement with experiments. Results show that the bilayer presents the same resonances as one of the subsets but modified by the presence of the other in its resonant frequencies and in the electric field distributions. As this distortion is not very large, the number of resonances in a selected spectral region is determined by the dominant subset. The degree of freedom that offers the bilayer could be useful to fine tune the resonances of the structure for different applications. A map of modes useful to guide this design is also presented. Scale invariance of Maxwell equations allows the translation of these results in the microwave range to the visible region; hence, some possible applications are discussed in this framework.

  7. Electromagnetic resonant modes of dielectric sphere bilayers

    NASA Astrophysics Data System (ADS)

    Andueza, A.; Pérez-Conde, J.; Sevilla, J.

    2015-05-01

    Sphere bilayers have been proposed as promising structures for electromagnetic management in photonic crystal devices. These arrangements are made of two intertwined subsets of spheres of different size and refractive index, one subset filling the interstitial sites of the other. We present a systematic study of the electromagnetic resonant modes of the bilayers, in comparison with those of the constituent subsets of spheres. Three samples were built with glass and Teflon spheres and their transmission spectra measured in the microwave range (10-25 GHz). Simulations with finite integration time-domain method are in good agreement with experiments. Results show that the bilayer presents the same resonances as one of the subsets but modified by the presence of the other in its resonant frequencies and in the electric field distributions. As this distortion is not very large, the number of resonances in a selected spectral region is determined by the dominant subset. The degree of freedom that offers the bilayer could be useful to fine tune the resonances of the structure for different applications. A map of modes useful to guide this design is also presented. Scale invariance of Maxwell equations allows the translation of these results in the microwave range to the visible region; hence, some possible applications are discussed in this framework.

  8. Graphene NanoElectroMechanical Resonators and Oscillators

    NASA Astrophysics Data System (ADS)

    Chen, Changyao

    Made of only one sheet of carbon atoms, graphene is the thinnest yet strongest material ever exist. Since its discovery in 2004, graphene has attracted tremendous research effort worldwide. Guaranteed by the superior electrical and excellent mechanical properties, graphene is the ideal building block for NanoElectroMechanical Systems (NEMS). In the first parts of the thesis, I will discuss the fabrications and measurements of typical graphene NEMS resonators, including doubly clamped and fully clamped graphene mechanical resonators. I have developed a electrical readout technique by using graphene as frequency mixer, demonstrated resonant frequencies in range from 30 to 200 MHz. Furthermore, I developed the advanced fabrications to achieve local gate structure, which led to the real-time resonant frequency detection under resonant channel transistor (RCT) scheme. Such real-time detection improve the measurement speed by 2 orders of magnitude compared to frequency mixing technique, and is critical for practical applications. Finally, I employed active balanced bridge technique in order to reduce overall electrical parasitics, and demonstrated pure capacitive transduction of graphene NEMS resonators. Characterizations of graphene NEMS resonators properties are followed, including resonant frequency and quality factor (Q) tuning with tension, mass and temperatures. A simple continuum mechanics model was constructed to understand the frequency tuning behavior, and it agrees with experimental data extremely well. In the following parts of the thesis, I will discuss the behavior of graphene mechanical resonators in applied magnetic field, i.e. in Quantum Hall (QH) regime. The couplings between mechanical motion and electronic band structure turned out to be a direct probe for thermodynamic quantities, i.e., chemical potential and compressibility. For a clean graphene resonators, with quality factors of 1 x 104, it underwent resonant frequency oscillations as applied

  9. Cyclotron resonance in graphene

    NASA Astrophysics Data System (ADS)

    Henriksen, Erik Alfred

    We present a study of cyclotron resonance in graphene. Graphene is a novel two-dimensional system consisting of a single sheet of atoms arranged in a honeycomb lattice, and exhibits a unique, linear low-energy dispersion. Bilayer graphene, two sheets stacked together, is an equally interesting system displaying a second unique, but hyperbolic, dispersion. In this work, we study the quantized Landau levels of these systems in strong magnetic fields, via Fourier-transform infrared spectroscopy. We have fabricated large area single layer and bilayer graphene devices on infrared-transparent Si/SiO2 substrates, using standard electron beam lithography and thin-film liftoff techniques. At cryogenic temperatures and high magnetic fields, we measure the infrared transmission through these devices as a function of the back gate voltage, which changes the Fermi level and hence the carrier density. We analyze the normalized transmission traces, assigning the observed minima to the cyclotron resonance wherein carriers are excited between Landau levels. In single layer graphene, we study Landau level transitions near the charge neutral Dirac point, and find a set of particle-hole symmetric transitions, both within the conduction and valence band, and between the bands. These experiments confirm the unusual B- and n -dependencies of the LL energies, where B is the magnetic field and n the LL index. The CR selection rule is determined to be Delta n = |nfinal| -- |n initial| = +/-1. The ratio of the observed interband and intraband transitions exceeds the expected value by 5%, and this excess is interpreted as an additional contribution to the transition energy from many-particle effects. We explore several higher LL transitions for both electron and hole doping of single layer graphene. The data are consistent with a renormalization of the carrier band velocity near the Dirac point, and suggest that impurity scattering strengthens at low energies. We also study the CR at the

  10. Electricity tommorrow

    NASA Astrophysics Data System (ADS)

    1981-01-01

    The critical issues for the electricity sector in California were presented. Adopted level of electricity demand and adopted policies and supply criteria are included. These form the basis for planning and certification of electric generation and transmission facilities by the energy commission. Estimates of the potential contributions of conservation and various conventional and alternative supply sources, critiques of utility supply plans, and determinations of how much new capacity is required are also included. Policy recommendations for directing public and private investments into preferred energy options, for spreading the benefits and costs of these options broadly and fairly among California's citizens, and for removing remaining obstacles to the development of all acceptable energy sources are presented.

  11. Directional Fano resonance in a silicon nanosphere dimer.

    PubMed

    Yan, Jiahao; Liu, Pu; Lin, Zhaoyong; Wang, Hao; Chen, Huanjun; Wang, Chengxin; Yang, Guowei

    2015-03-24

    Fano resonance arising from the interaction between a broad "bright" mode and a narrow "dark" mode has been widely investigated in symmetry-breaking structures made of noble metals such as plasmonic asymmetric oligomers or other well-designed nanostructures. However, Fano resonance in nanoscale all-dielectric dimers has not been experimentally demonstrated so far. We report the first experimental observation of directional Fano resonance in silicon nanosphere dimers (both homodimer and heterodimer) and clarify that the coupling between magnetic and electric dipole modes can easily generate Fano resonance in all-dielectric oligomers, distinctly differing from conventional Fano resonances based on electric responses or artificial optical magnetism. A silicon nanosphere dimer, exhibiting a strong magnetic response inside and an electric enhancement in the gap, is an excellent structure to support magnetic-based Fano scattering. Interactions between magnetic and electric dipoles can suppress backward scattering and enhance forward scattering at Fano wavelengths. This directional scattering is much more prominent than that from a single silicon sphere and shows promising applications in areas such as directional nanoantenna or optical switching, opening up avenues for developing all-dielectric low-loss metamaterials or nanophotonic devices at visible wavelengths. PMID:25683067

  12. Excitation of plasmonic nanoantennas by nonresonant and resonant electron tunnelling

    NASA Astrophysics Data System (ADS)

    Uskov, Alexander V.; Khurgin, Jacob B.; Protsenko, Igor E.; Smetanin, Igor V.; Bouhelier, Alexandre

    2016-07-01

    A rigorous theory of photon emission generated by inelastic electron tunnelling inside the gap of plasmonic nanoantennas is developed. The disappointingly low efficiency of the electrical excitation of surface plasmon polaritons in these structures can be increased by orders of magnitude when a resonant tunnelling structure is incorporated inside the gap. A resonant tunnelling assisted surface plasmon emitter may become a key element in future electrically-driven plasmonic nanocircuits.A rigorous theory of photon emission generated by inelastic electron tunnelling inside the gap of plasmonic nanoantennas is developed. The disappointingly low efficiency of the electrical excitation of surface plasmon polaritons in these structures can be increased by orders of magnitude when a resonant tunnelling structure is incorporated inside the gap. A resonant tunnelling assisted surface plasmon emitter may become a key element in future electrically-driven plasmonic nanocircuits. Electronic supplementary information (ESI) available: Plasmonic mode in nanowires, the probability of stimulated emission in tunnelling through the Fermi's Golden Rule and electron wave functions in tunnelling structures with nonresonant and resonant tunnelling. See DOI: 10.1039/c6nr01931e

  13. Resonant Raman scattering from silicon nanoparticles enhanced by magnetic response.

    PubMed

    Dmitriev, Pavel A; Baranov, Denis G; Milichko, Valentin A; Makarov, Sergey V; Mukhin, Ivan S; Samusev, Anton K; Krasnok, Alexander E; Belov, Pavel A; Kivshar, Yuri S

    2016-05-01

    Enhancement of optical response with high-index dielectric nanoparticles is attributed to the excitation of their Mie-type magnetic and electric resonances. Here we study Raman scattering from crystalline silicon nanoparticles and reveal that magnetic dipole modes have a much stronger effect on the scattering than electric modes of the same order. We demonstrate experimentally a 140-fold enhancement of the Raman signal from individual silicon spherical nanoparticles at the magnetic dipole resonance. Our results confirm the importance of the optically-induced magnetic response of subwavelength dielectric nanoparticles for enhancing light-matter interactions. PMID:27113352

  14. Electron Paramagnetic Resonance of Single Magnetic Moment on a Surface.

    PubMed

    Berggren, P; Fransson, J

    2016-01-01

    We address electron spin resonance of single magnetic moments in a tunnel junction using time-dependent electric fields and spin-polarized current. We show that the tunneling current directly depends on the local magnetic moment and that the frequency of the external electric field mixes with the characteristic Larmor frequency of the local spin. The importance of the spin-polarized current induced anisotropy fields acting on the local spin moment is, moreover, demonstrated. Our proposed model thus explains the absence of an electron spin resonance for a half integer spin, in contrast with the strong signal observed for an integer spin. PMID:27156935

  15. Electron Paramagnetic Resonance of Single Magnetic Moment on a Surface

    PubMed Central

    Berggren, P.; Fransson, J.

    2016-01-01

    We address electron spin resonance of single magnetic moments in a tunnel junction using time-dependent electric fields and spin-polarized current. We show that the tunneling current directly depends on the local magnetic moment and that the frequency of the external electric field mixes with the characteristic Larmor frequency of the local spin. The importance of the spin-polarized current induced anisotropy fields acting on the local spin moment is, moreover, demonstrated. Our proposed model thus explains the absence of an electron spin resonance for a half integer spin, in contrast with the strong signal observed for an integer spin. PMID:27156935

  16. Electron paramagnetic resonance of individual atoms on a surface.

    PubMed

    Baumann, Susanne; Paul, William; Choi, Taeyoung; Lutz, Christopher P; Ardavan, Arzhang; Heinrich, Andreas J

    2015-10-23

    We combined the high-energy resolution of conventional spin resonance (here ~10 nano-electron volts) with scanning tunneling microscopy to measure electron paramagnetic resonance of individual iron (Fe) atoms placed on a magnesium oxide film. We drove the spin resonance with an oscillating electric field (20 to 30 gigahertz) between tip and sample. The readout of the Fe atom's quantum state was performed by spin-polarized detection of the atomic-scale tunneling magnetoresistance. We determine an energy relaxation time of T1 ≈ 100 microseconds and a phase-coherence time of T2 ≈ 210 nanoseconds. The spin resonance signals of different Fe atoms differ by much more than their resonance linewidth; in a traditional ensemble measurement, this difference would appear as inhomogeneous broadening. PMID:26494753

  17. Reflection resonance switching in metamaterial twisted nematics cell.

    PubMed

    Lee, Y U; Choi, E Y; Woo, J H; Kim, E S; Wu, J W

    2013-07-29

    Electric switching of reflection resonances at near-IR spectral range is experimentally demonstrated in a reflective metamaterial twisted nematic liquid crystal cell. Reflective metamaterial composed of nano-sized double-split ring resonator aperture is fabricated by a focused ion beam milling. Two-fold rotational symmetry of double-split ring resonators allows for two orthogonal polarization-dependent reflection resonances in the reflective metamaterial. With an external voltage of 10V across 12μm cell gap, a full switching is achieved between two reflection resonances. Dynamic measurements show the time constants of switch-on and switch-off are in the order of 100ms and 10ms, respectively. PMID:23938619

  18. Dual band metamaterial perfect absorber based on Mie resonances

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoming; Lan, Chuwen; Bi, Ke; Li, Bo; Zhao, Qian; Zhou, Ji

    2016-08-01

    We numerically and experimentally demonstrated a polarization insensitive dual-band metamaterial perfect absorber working in wide incident angles based on the two magnetic Mie resonances of a single dielectric "atom" with simple structure. Two absorption bands with simulated absorptivity of 99% and 96%, experimental absorptivity of 97% and 94% at 8.45 and 11.97 GHz were achieved due to the simultaneous magnetic and electric resonances in dielectric "atom" and copper plate. Mie resonances of dielectric "atom" provide a simple way to design metamaterial perfect absorbers with high symmetry.

  19. Electrically powered hand tool

    DOEpatents

    Myers, Kurt S.; Reed, Teddy R.

    2007-01-16

    An electrically powered hand tool is described and which includes a three phase electrical motor having a plurality of poles; an electrical motor drive electrically coupled with the three phase electrical motor; and a source of electrical power which is converted to greater than about 208 volts three-phase and which is electrically coupled with the electrical motor drive.

  20. Multiple magnetic mode-based Fano resonance in split-ring resonator/disk nanocavities.

    PubMed

    Zhang, Qing; Wen, Xinglin; Li, Guangyuan; Ruan, Qifeng; Wang, Jianfang; Xiong, Qihua

    2013-12-23

    Plasmonic Fano resonance, enabled by the weak interaction between a bright super-radiant and a subradiant resonance mode, not only is fundamentally interesting, but also exhibits potential applications ranging from extraordinary optical transmission to biosensing. Here, we demonstrate strong Fano resonances in split-ring resonators/disk (SRR/D) nanocavities. The high-order magnetic modes are observed in SRRs by polarization-resolved transmission spectroscopy. When a disk is centered within the SRRs, multiple high-order magnetic modes are coupled to a broad electric dipole mode of SRR/D, leading to significant Fano resonance spectral features in near-IR regime. The strength and line shape of the Fano resonances are tuned through varying the SRR split-angle and interparticle distance between SRR and disk. Finite-difference-time-domain (FDTD) simulations are conducted to understand the coupling mechanism, and the results show good agreement with experimental data. Furthermore, the coupled structure gives a sensitivity of ∼282 nm/RIU with a figure of merit ∼4. PMID:24215162

  1. LABCOM resonator Phase 3

    SciTech Connect

    Keres, L.J.

    1990-11-01

    The purpose of this project was to develop quartz crystal resonator designs, production processes, and test capabilities for 5-MHz, 6.2-MHz, and 10-MHz resonators for Tactical Miniature Crystal Oscillator (TMXO) applications. GE Neutron Devices (GEND) established and demonstrated the capability to produce and test quartz crystal resonators for use in the TMXO developed by the US Army ERADCOM (now LABCOM). The goals in this project were based on the ERADCOM statement of work. The scope of work indicated that the resonator production facilities for this project would not be completely independent, but that they would be supported in part by equipment and processes in place at GEND used in US Department of Energy (DOE) work. In addition, provisions for production test equipment or or eventual technology transfer costs to a commercial supplier were clearly excluded from the scope of work. The demonstrated technical capability of the deep-etched blank design is feasible and practical. It can be manufactured in quantity with reasonable yield, and its performance is readily predictable. The ceramic flatpack is a very strong package with excellent hermeticity. The four-point mount supports the crystal to reasonable shock levels and does not perturb the resonator's natural frequency-temperature behavior. The package can be sealed with excellent yields. The high-temperature, high-vacuum processing developed for the TMXO resonator, including bonding the piezoid to its mount with conductive polyimide adhesive, is consistent with precision resonator fabrication. 1 fig., 6 tabs.

  2. Modelling resonant planetary systems

    NASA Astrophysics Data System (ADS)

    Emel'yanenko, V.

    2012-09-01

    Many discovered multi-planet systems are in meanmotion resonances. The aim of this work is to study dynamical processes leading to the formation of resonant configurations on the basis of a unified model described earlier [1]. The model includes gravitational interactions of planets and migration of planets due to the presence of a gas disc. For the observed systems 24 Sex, HD 37124, HD 73526, HD 82943, HD 128311, HD 160691, Kepler 9, NN Ser with planets moving in the 2:1 resonance, it is shown that the capture in this resonance occurs at very wide ranges of parameters of both type I and type II migration. Conditions of migration leading to the formation of the resonant systems HD 45364 и HD 200964 (3:2 and 4:3, respectively) are obtained. Formation scenarios are studied for the systems HD 102272, HD 108874, HD 181433, HD 202206 with planets in high order resonances. We discuss also how gravitational interactions of planets and planetesimal discs lead to the breakup of resonant configurations and the formation of systems similar to the 47 UMa system.

  3. Electrically charged curvaton

    SciTech Connect

    D'Onofrio, Michela; Lerner, Rose N.; Rajantie, Arttu E-mail: rose.lerner@helsinki.fi

    2012-10-01

    We consider the possibility that the primordial curvature perturbation was generated through the curvaton mechanism from a scalar field with an electric charge, or precisely the Standard Model U(1) weak hypercharge. This links the dynamics of the very early universe concretely to the Standard Model of particle physics, and because the coupling strength is known, it reduces the number of free parameters in the curvaton model. The gauge coupling also introduces several new physical effects. Charge fluctuations are generated during inflation, but they are screened by electron-positron pairs therefore do not violate observational constraints. After inflation, the curvaton interacts with thermal radiation which destroys the curvaton condensate and prevents the generation of curvature perturbations, unless the inflaton dynamics satisfy strong constraints. The curvaton also experiences a period of parametric resonance with the U(1) gauge field. Using the standard perturbative approach, we find that the model can generate the observed density perturbation for Hubble rate H{sub *}∼>10{sup 8}GeV and curvaton mass m∼>10{sup −2}H{sub *}, but with a level of non-Gaussianity (f{sub NL}∼>130) that violates observational constraints. However, previous studies have shown that the parametric resonance changes the predicted perturbations significantly, and therefore fully non-linear numerical field theory simulations are required.

  4. Electrical Injuries

    MedlinePlus

    ... your injuries are depends on how strong the electric current was, what type of current it was, how it moved through your body, and how long you were exposed. Other factors include how ... you should see a doctor. You may have internal damage and not realize it.

  5. Spin resonance strength calculations

    SciTech Connect

    Courant,E.D.

    2008-10-06

    In calculating the strengths of depolarizing resonances it may be convenient to reformulate the equations of spin motion in a coordinate system based on the actual trajectory of the particle, as introduced by Kondratenko, rather than the conventional one based on a reference orbit. It is shown that resonance strengths calculated by the conventional and the revised formalisms are identical. Resonances induced by radiofrequency dipoles or solenoids are also treated; with rf dipoles it is essential to consider not only the direct effect of the dipole but also the contribution from oscillations induced by it.

  6. Tunable multiwalled nanotube resonator

    DOEpatents

    Zettl, Alex K.; Jensen, Kenneth J.; Girit, Caglar; Mickelson, William E.; Grossman, Jeffrey C.

    2011-03-29

    A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.

  7. Tunable multiwalled nanotube resonator

    DOEpatents

    Jensen, Kenneth J; Girit, Caglar O; Mickelson, William E; Zettl, Alexander K; Grossman, Jeffrey C

    2013-11-05

    A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.

  8. Tuning Coler Magnetic Current Apparatus with Magneto-Acoustic Resonance

    NASA Astrophysics Data System (ADS)

    Ludwig, Thorsten

    An attempt was made to tune the Coler magnetic current apparatus with the magneto acoustic resonance of the magnetic rods. Measurements with a replica of the famous Coler "Magnetstromapparat" were conducted. In order to tune the acoustic, magnetic and electric resonance circuits of the Coler device the magneto-acoustic resonance was measured with a frequency scan through a function generator and a lock-in amplifier. The frequency generator was powering a driving coil, while the lock-in was connected to a pickup coil. Both coils were placed on a magnetic rod. Resonances were observed up to the 17th harmonic. The quality Q of the observed resonances was 270. To study the magneto-acoustic resonance in the time domain a pair of Permendur rods were employed. The magneto-acoustic resonances of the Permendur rods were observed with an oscilloscope. Spectra of the magneto acoustic resonance were measured for the Permendur rods and for a Coler replica magnet in the frequency range from 25 kHz to 380 kHz. The next step was to bring the resonances of the Permendur rods close together so that they overlap. The 10thharmonic was chosen because it was close to the 180 kHz that Hans Coler related to ferromagnetism. Further more magneto-acoustic coupling between the Permendur rods was studied. Finally the question was explored if Hans Coler converted vacuum fluctuations via magnetic and acoustic resonance into electricity. There is a strong connection between magnetism and quantum field zero point energy (ZPE). An outlook is given on next steps in the experiments to unveil the working mechanism of the Coler magnetic current apparatus.

  9. Voltage control of ferromagnetic resonance

    NASA Astrophysics Data System (ADS)

    Zhou, Ziyao; Peng, Bin; Zhu, Mingmin; Liu, Ming

    2016-05-01

    Voltage control of magnetism in multiferroics, where the ferromagnetism and ferroelectricity are simultaneously exhibiting, is of great importance to achieve compact, fast and energy efficient voltage controllable magnetic/microwave devices. Particularly, these devices are widely used in radar, aircraft, cell phones and satellites, where volume, response time and energy consumption is critical. Researchers realized electric field tuning of magnetic properties like magnetization, magnetic anisotropy and permeability in varied multiferroic heterostructures such as bulk, thin films and nanostructure by different magnetoelectric (ME) coupling mechanism: strain/stress, interfacial charge, spin-electromagnetic (EM) coupling and exchange coupling, etc. In this review, we focus on voltage control of ferromagnetic resonance (FMR) in multiferroics. ME coupling-induced FMR change is critical in microwave devices, where the electric field tuning of magnetic effective anisotropic field determines the tunability of the performance of microwave devices. Experimentally, FMR measurement technique is also an important method to determine the small effective magnetic field change in small amount of magnetic material precisely due to its high sensitivity and to reveal the deep science of multiferroics, especially, voltage control of magnetism in novel mechanisms like interfacial charge, spin-EM coupling and exchange coupling.

  10. Dynamics of morphology-dependent resonances by openness in dielectric disks for TE polarization

    SciTech Connect

    Cho, Jinhang; Rim, Sunghwan; Kim, Chil-Min

    2011-04-15

    We have studied the parametric evolution of morphology-dependent resonances according to the change of openness in a two-dimensional dielectric microdisk for transverse-electric polarization. We found that the dynamics exhibit avoided resonance crossings between the inner and outer resonances even though the corresponding billiard is integrable. Due to these recondite avoidances, inner and outer resonances can be exchanged and the quality (Q) factor of inner resonances is strongly affected. We analyze the diverse phenomena arising from these dynamics including the avoided crossings.

  11. Dual-band terahertz metamaterials based on nested split ring resonators

    NASA Astrophysics Data System (ADS)

    Hussain, Sajid; Min Woo, Jeong; Jang, Jae-Hyung

    2012-08-01

    Two dual-band terahertz metamaterials based on nested split ring resonators (SRRs) were designed and fabricated on a flexible plastic substrate. Each nested SRR structure composed of two electric field coupled resonators exhibited two transmission minimums, which inherently come from the LC resonances of the respective SRRs. The primary and secondary resonance frequencies can be individually fine-tuned by adjusting the geometry of the respective resonator. The fabricated devices exhibited very low insertion loss of 3 dB in the transmission band and the high attenuation of 27 dB in the stop band.

  12. Linear oscillations of a drop in uniform alternating electric fields

    SciTech Connect

    Yang, Wenrui; Carleson, T.E.

    1990-10-01

    Oscillations of a conducting drop immersed in a dielectric fluid in an alternating electric field has been modelled in order to understand the enhancement of the transport processes by the electric field. Numerical solutions for oscillation amplitude, velocity distribution, resonant frequency and streamlines were obtained. The effects of viscosity and density on the resonant frequency and the velocity distribution were investigated. It was found that the resonant frequency of viscous fluids was always smaller than the free oscillation frequency of the same droplet. The predicted scanning frequency response curve and the streamlines agree well with the experimental observations.

  13. Electric current induced modification of germanium nanowire NEM switch contact

    NASA Astrophysics Data System (ADS)

    Meija, R.; Kosmaca, J.; Jasulaneca, L.; Petersons, K.; Biswas, S.; Holmes, J. D.; Erts, D.

    2015-05-01

    We present an investigation of contact properties of a germanium (Ge) nanowire based nanoelectromechanical (NEM) switch in its ON state. The contact stiffness in the ON state was evaluated by detecting the nanowire’s resonance frequency. It was found that the resonance frequency increases when electric current flows through the nanowire/counter electrode contact area. The reason for modification in the contact area is referred to as electric-current-induced processes in the native oxide layer covering the nanowires. The presented resonance shift method is a simple way to indicate strengthening of the nanowire/counter electrode contact area without disassembling the contact.

  14. Electric current induced modification of germanium nanowire NEM switch contact.

    PubMed

    Meija, R; Kosmaca, J; Jasulaneca, L; Petersons, K; Biswas, S; Holmes, J D; Erts, D

    2015-05-15

    We present an investigation of contact properties of a germanium (Ge) nanowire based nanoelectromechanical (NEM) switch in its ON state. The contact stiffness in the ON state was evaluated by detecting the nanowire's resonance frequency. It was found that the resonance frequency increases when electric current flows through the nanowire/counter electrode contact area. The reason for modification in the contact area is referred to as electric-current-induced processes in the native oxide layer covering the nanowires. The presented resonance shift method is a simple way to indicate strengthening of the nanowire/counter electrode contact area without disassembling the contact. PMID:25902759

  15. A closed-loop wide-range tunable mechanical resonator for energy harvesting systems

    NASA Astrophysics Data System (ADS)

    Peters, Christian; Maurath, Dominic; Schock, Wolfram; Mezger, Florian; Manoli, Yiannos

    2009-09-01

    This paper presents a novel electrically tunable structure which can be used as a resonator for vibration-based energy harvesters. The adjustment of the resonance frequency is provided by mechanical stiffening of the structure using piezoelectric actuators. This concept can easily be stand-alone integrated to realize an autonomous, tunable harvester. The resonator was simulated using ANSYS to find the optimum operation point concerning tuning range. The scalability of this tuning concept is also investigated in this work. A phase shift control circuit was developed for very efficient autonomous closed-loop control of the resonance frequency. Prototypes of the resonators were fabricated and measured with and without the control circuit. The tuning voltage can be kept as low as ±5 V leading to a measured resonance shift of ±15% for the larger resonator (40 mm) and around ±8% for the smaller resonator (27 mm). This tuning range can be simply enhanced by increasing the tuning voltage.

  16. Micro-machined resonator

    DOEpatents

    Godshall, N.A.; Koehler, D.R.; Liang, A.Y.; Smith, B.K.

    1993-03-30

    A micro-machined resonator, typically quartz, with upper and lower micro-machinable support members, or covers, having etched wells which may be lined with conductive electrode material, between the support members is a quartz resonator having an energy trapping quartz mesa capacitively coupled to the electrode through a diaphragm; the quartz resonator is supported by either micro-machined cantilever springs or by thin layers extending over the surfaces of the support. If the diaphragm is rigid, clock applications are available, and if the diaphragm is resilient, then transducer applications can be achieved. Either the thin support layers or the conductive electrode material can be integral with the diaphragm. In any event, the covers are bonded to form a hermetic seal and the interior volume may be filled with a gas or may be evacuated. In addition, one or both of the covers may include oscillator and interface circuitry for the resonator.

  17. Micro-machined resonator

    DOEpatents

    Godshall, Ned A.; Koehler, Dale R.; Liang, Alan Y.; Smith, Bradley K.

    1993-01-01

    A micro-machined resonator, typically quartz, with upper and lower micro-machinable support members, or covers, having etched wells which may be lined with conductive electrode material, between the support members is a quartz resonator having an energy trapping quartz mesa capacitively coupled to the electrode through a diaphragm; the quartz resonator is supported by either micro-machined cantilever springs or by thin layers extending over the surfaces of the support. If the diaphragm is rigid, clock applications are available, and if the diaphragm is resilient, then transducer applications can be achieved. Either the thin support layers or the conductive electrode material can be integral with the diaphragm. In any event, the covers are bonded to form a hermetic seal and the interior volume may be filled with a gas or may be evacuated. In addition, one or both of the covers may include oscillator and interface circuitry for the resonator.

  18. Resonances in QCD

    NASA Astrophysics Data System (ADS)

    Lutz, Matthias F. M.; Lange, Jens Sören; Pennington, Michael; Bettoni, Diego; Brambilla, Nora; Crede, Volker; Eidelman, Simon; Gillitzer, Albrecht; Gradl, Wolfgang; Lang, Christian B.; Metag, Volker; Nakano, Takashi; Nieves, Juan; Neubert, Sebastian; Oka, Makoto; Olsen, Stephen L.; Pappagallo, Marco; Paul, Stephan; Pelizäus, Marc; Pilloni, Alessandro; Prencipe, Elisabetta; Ritman, Jim; Ryan, Sinead; Thoma, Ulrike; Uwer, Ulrich; Weise, Wolfram

    2016-04-01

    We report on the EMMI Rapid Reaction Task Force meeting 'Resonances in QCD', which took place at GSI October 12-14, 2015. A group of 26 people met to discuss the physics of resonances in QCD. The aim of the meeting was defined by the following three key questions: What is needed to understand the physics of resonances in QCD? Where does QCD lead us to expect resonances with exotic quantum numbers? What experimental efforts are required to arrive at a coherent picture? For light mesons and baryons only those with up, down and strange quark content were considered. For heavy-light and heavy-heavy meson systems, those with charm quarks were the focus. This document summarizes the discussions by the participants, which in turn led to the coherent conclusions we present here.

  19. Resonances in Positronium Hydride

    NASA Technical Reports Server (NTRS)

    DiRienzi, Joseph; Drachman, Richard J.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We re-examine the problem of calculating the positions and widths of the lowest-lying resonances in the Ps + H scattering system which consists of two electrons, one positron and one proton. The first of these resonances, for L=0, was found by the methods of complex rotation and stabilization, and later described as a Feshbach resonance lying close to a bound state in the closed-channel e (+) + H (-) system. Recently, results for the L=1 and 2 scattering states were published, and it was found, surprisingly, that there is a larae shift in the positions of these resonances. In this work we repeat the analysis for L=1 and find an unexpected explanation for the shift.

  20. Resonant ultrasound spectroscopy

    DOEpatents

    Migliori, Albert

    1991-01-01

    A resonant ultrasound spectroscopy method provides a unique characterization of an object for use in distinguishing similar objects having physical differences greater than a predetermined tolerance. A resonant response spectrum is obtained for a reference object by placing excitation and detection transducers at any accessible location on the object. The spectrum is analyzed to determine the number of resonant response peaks in a predetermined frequency interval. The distribution of the resonance frequencies is then characterized in a manner effective to form a unique signature of the object. In one characterization, a small frequency interval is defined and stepped though the spectrum frequency range. Subsequent objects are similarly characterized where the characterizations serve as signatures effective to distinguish objects that differ from the reference object by more than the predetermined tolerance.

  1. Dual-band microwave duplexer based on spiral resonators (SR) and complementary split ring resonators (CSRR)

    NASA Astrophysics Data System (ADS)

    Vélez, A.; Sisó, G.; Campo, A.; Durán-Sindreu, M.; Bonache, J.; Martín, F.

    2011-06-01

    In this work, a microstrip dual-band microwave duplexer implemented by means of a pair of dual-band branch-line hybrid couplers and a pair of dual-band band-stop filters is presented. The hybrid couplers are implemented by using complementary split ring resonators (CSRRs), etched in the ground plane, while the band-stop filters are made of spiral resonators (SRs) coupled to the host line. The measured duplexer characteristics are good and the device is compact by virtue of the small electrical size of the employed resonant elements. From this paper, it is clear that CSRRs and SRs are useful particles for the design of dual-band microwave systems requiring various microwave components.

  2. Cylindrical laser resonator

    DOEpatents

    Casperson, Lee W.

    1976-02-24

    The properties of an improved class of lasers is presented. In one configuration of these lasers the radiation propagates radially within the amplifying medium, resulting in high fields and symmetric illumination at the resonator axis. Thus there is a strong focusing of energy at the axis of the resonator. In a second configuration the radiation propagates back and forth in a tubular region of space.

  3. Injector with integrated resonator

    SciTech Connect

    Johnson, Thomas Edward; Ziminsky, Willy Steve; York, William David; Stevenson, Christian Xavier

    2014-07-29

    The system may include a turbine engine. The turbine engine may include a fuel nozzle. The fuel nozzle may include an air path. The fuel nozzle may also include a fuel path such that the fuel nozzle is in communication with a combustion zone of the turbine engine. Furthermore, the fuel nozzle may include a resonator. The resonator may be disposed in the fuel nozzle directly adjacent to the combustion zone.

  4. Hexagonal quartz resonator

    DOEpatents

    Peters, Roswell D. M.

    1982-01-01

    A generally flat, relatively thin AT-cut piezoelectric resonator element structured to minimize the force-frequency effect when mounted and energized in a housing. The resonator is in the form of an equilateral hexagon with the X crystallographic axis of the crystal passing through one set of opposing corners with mounting being effected at an adjacent set of corners respectively .+-.60.degree. away from the X axis which thereby results in a substantially zero frequency shift of the operating frequency.

  5. Resonant dielectric metamaterials

    SciTech Connect

    Loui, Hung; Carroll, James; Clem, Paul G; Sinclair, Michael B

    2014-12-02

    A resonant dielectric metamaterial comprises a first and a second set of dielectric scattering particles (e.g., spheres) having different permittivities arranged in a cubic array. The array can be an ordered or randomized array of particles. The resonant dielectric metamaterials are low-loss 3D isotropic materials with negative permittivity and permeability. Such isotropic double negative materials offer polarization and direction independent electromagnetic wave propagation.

  6. Plasmofluidic Disk Resonators

    PubMed Central

    Kwon, Min-Suk; Ku, Bonwoo; Kim, Yonghan

    2016-01-01

    Waveguide-coupled silicon ring or disk resonators have been used for optical signal processing and sensing. Large-scale integration of optical devices demands continuous reduction in their footprints, and ultimately they need to be replaced by silicon-based plasmonic resonators. However, few waveguide-coupled silicon-based plasmonic resonators have been realized until now. Moreover, fluid cannot interact effectively with them since their resonance modes are strongly confined in solid regions. To solve this problem, this paper reports realized plasmofluidic disk resonators (PDRs). The PDR consists of a submicrometer radius silicon disk and metal laterally surrounding the disk with a 30-nm-wide channel in between. The channel is filled with fluid, and the resonance mode of the PDR is strongly confined in the fluid. The PDR coupled to a metal-insulator-silicon-insulator-metal waveguide is implemented by using standard complementary metal oxide semiconductor technology. If the refractive index of the fluid increases by 0.141, the transmission spectrum of the waveguide coupled to the PDR of radius 0.9 μm red-shifts by 30 nm. The PDR can be used as a refractive index sensor requiring a very small amount of analyte. Plus, the PDR filled with liquid crystal may be an ultracompact intensity modulator which is effectively controlled by small driving voltage. PMID:26979929

  7. Plasmofluidic Disk Resonators

    NASA Astrophysics Data System (ADS)

    Kwon, Min-Suk; Ku, Bonwoo; Kim, Yonghan

    2016-03-01

    Waveguide-coupled silicon ring or disk resonators have been used for optical signal processing and sensing. Large-scale integration of optical devices demands continuous reduction in their footprints, and ultimately they need to be replaced by silicon-based plasmonic resonators. However, few waveguide-coupled silicon-based plasmonic resonators have been realized until now. Moreover, fluid cannot interact effectively with them since their resonance modes are strongly confined in solid regions. To solve this problem, this paper reports realized plasmofluidic disk resonators (PDRs). The PDR consists of a submicrometer radius silicon disk and metal laterally surrounding the disk with a 30-nm-wide channel in between. The channel is filled with fluid, and the resonance mode of the PDR is strongly confined in the fluid. The PDR coupled to a metal-insulator-silicon-insulator-metal waveguide is implemented by using standard complementary metal oxide semiconductor technology. If the refractive index of the fluid increases by 0.141, the transmission spectrum of the waveguide coupled to the PDR of radius 0.9 μm red-shifts by 30 nm. The PDR can be used as a refractive index sensor requiring a very small amount of analyte. Plus, the PDR filled with liquid crystal may be an ultracompact intensity modulator which is effectively controlled by small driving voltage.

  8. Resonant nonlinear ultrasound spectroscopy

    DOEpatents

    Johnson, Paul A.; TenCate, James A.; Guyer, Robert A.; Van Den Abeele, Koen E. A.

    2001-01-01

    Components with defects are identified from the response to strains applied at acoustic and ultrasound frequencies. The relative resonance frequency shift .vertline..DELTA..function./.function..sub.0.vertline., is determined as a function of applied strain amplitude for an acceptable component, where .function..sub.0 is the frequency of the resonance peak at the lowest amplitude of applied strain and .DELTA..function. is the frequency shift of the resonance peak of a selected mode to determine a reference relationship. Then, the relative resonance frequency shift .vertline..DELTA..function./.function..sub.0 is determined as a function of applied strain for a component under test, where fo .function..sub.0 the frequency of the resonance peak at the lowest amplitude of applied strain and .DELTA..function. is the frequency shift of the resonance peak to determine a quality test relationship. The reference relationship is compared with the quality test relationship to determine the presence of defects in the component under test.

  9. Electricity unplugged

    NASA Astrophysics Data System (ADS)

    Karalis, Aristeidis

    2009-02-01

    The judge was driving back late one cold winter night. Entering the garage, the battery-charging indicator in his wirelessly powered electric car came on. "Home at last," crossed his mind. He swiped his personal smartcard on the front-door detector to be let in. He heard a "charging" beep from his mobile phone. The blinking cursor on the half-finished e-mail on the laptop had been waiting all day on the side table. He picked the computer up and walked towards his desk. "Good evening, your honour. Your wirelessly heated robe," said the butler-robot as it approached from the kitchen. Putting on the electric garment, he sat on the medical desk chair. His artificial heart was now beating faster.

  10. Molecular dynamics in high electric fields

    NASA Astrophysics Data System (ADS)

    Apostol, M.; Cune, L. C.

    2016-06-01

    Molecular rotation spectra, generated by the coupling of the molecular electric-dipole moments to an external time-dependent electric field, are discussed in a few particular conditions which can be of some experimental interest. First, the spherical-pendulum molecular model is reviewed, with the aim of introducing an approximate method which consists in the separation of the azimuthal and zenithal motions. Second, rotation spectra are considered in the presence of a static electric field. Two particular cases are analyzed, corresponding to strong and weak fields. In both cases the classical motion of the dipoles consists of rotations and vibrations about equilibrium positions; this motion may exhibit parametric resonances. For strong fields a large macroscopic electric polarization may appear. This situation may be relevant for polar matter (like pyroelectrics, ferroelectrics), or for heavy impurities embedded in a polar solid. The dipolar interaction is analyzed in polar condensed matter, where it is shown that new polarization modes appear for a spontaneous macroscopic electric polarization (these modes are tentatively called "dipolons"); one of the polarization modes is related to parametric resonances. The extension of these considerations to magnetic dipoles is briefly discussed. The treatment is extended to strong electric fields which oscillate with a high frequency, as those provided by high-power lasers. It is shown that the effect of such fields on molecular dynamics is governed by a much weaker, effective, renormalized, static electric field.

  11. Acoustic stabilization of electric arc instabilities in nontransferred plasma torches

    SciTech Connect

    Rat, V.; Coudert, J. F.

    2010-03-08

    Electric arc instabilities in dc plasma torches lead to nonhomogeneous treatments of nanosized solid particles or liquids injected within thermal plasma jets. This paper shows that an additional acoustic resonator mounted on the cathode cavity allows reaching a significant damping of these instabilities, particularly the Helmholtz mode of arc oscillations. The acoustic resonator is coupled with the Helmholtz resonator of the plasma torch limiting the amplitude of arc voltage variations. It is also highlighted that this damping is dependent on friction effects in the acoustic resonator.

  12. Observation of Fano resonances in all-dielectric nanoparticle oligomers.

    PubMed

    Chong, Katie E; Hopkins, Ben; Staude, Isabelle; Miroshnichenko, Andrey E; Dominguez, Jason; Decker, Manuel; Neshev, Dragomir N; Brener, Igal; Kivshar, Yuri S

    2014-05-28

    It is well-known that oligomers made of metallic nanoparticles are able to support sharp Fano resonances originating from the interference of two plasmonic resonant modes with different spectral width. While such plasmonic oligomers suffer from high dissipative losses, a new route for achieving Fano resonances in nanoparticle oligomers has opened up after the recent experimental observations of electric and magnetic resonances in low-loss dielectric nanoparticles. Here, light scattering by all-dielectric oligomers composed of silicon nanoparticles is studied experimentally for the first time. Pronounced Fano resonances are observed for a variety of lithographically-fabricated heptamer nanostructures consisting of a central particle of varying size, encircled by six nanoparticles of constant size. Based on a full collective mode analysis, the origin of the observed Fano resonances is revealed as a result of interference of the optically-induced magnetic dipole mode of the central particle with the collective mode of the nanoparticle structure. This allows for effective tuning of the Fano resonance to a desired spectral position by a controlled size variation of the central particle. Such optically-induced magnetic Fano resonances in all-dielectric oligomers offer new opportunities for sensing and nonlinear applications. PMID:24616191

  13. Broadband resonances in indium-tin-oxide nanorod arrays

    SciTech Connect

    Li, Shi-Qiang E-mail: r-chang@northwestern.edu; Sakoda, Kazuaki; Ketterson, John B.; Chang, Robert P. H. E-mail: r-chang@northwestern.edu

    2015-07-20

    There is currently much discussion within the nanophotonics community regarding the origin of wavelength selective absorption/scattering of light by the resonances in nanorod arrays. Here, we report a study of resonances in ordered indium-tin-oxide nanorod arrays resulting from waveguide-like modes. We find that with only a 2.4% geometrical coverage, micron-length nanorod arrays interact strongly with light across a surprisingly wide band from the visible to the mid-infrared, resulting in less than 10% transmission. Simulations show excellent agreement with our experimental observations. The field profile in the vicinity of the rods obtained from simulations shows that the electric field is mainly localized on the surfaces of the nanorods for all resonances. Based on our analysis, the resonances in the visible are different in character from those in the infrared. When light is incident on the array, part of it propagates in the space between the rods and part of it is guided within the rods. The phase difference (interference) at the ends of the rods forms the basis for the resonances in the visible region. The resonances in the infrared are Fabry-Perot-like resonances involving standing surface waves between the opposing ends of the rods. Simple analytical formulae predict the spectral positions of these resonances. It is suggested that these phenomena can be utilized for wavelength-selective photodetectors, modulators, and nanorod-based solar cells.

  14. Ultra-high Q even eigenmode resonance in terahertz metamaterials

    SciTech Connect

    Al-Naib, Ibraheem Dignam, Marc M.; Yang, Yuping; Zhang, Weili; Singh, Ranjan

    2015-01-05

    We report the simultaneous excitation of the odd and the even eigenmode resonances in a periodic array of square split-ring resonators, with four resonators per unit cell. When the electric field is parallel to their gaps, only the two well-studied odd eigenmodes are excited. As the resonators are rotated relative to one another, we observe the emergence and excitation of an extremely sharp even eigenmode. In uncoupled split-ring resonators, this even eigenmode is typically radiative in nature with a broad resonance linewidth and low Q-factor. However, in our coupled system, for specific range of rotation angles, our simulations revealed a remarkably high quality factor (Q ∼ 100) for this eigenmode, which has sub-radiant characteristics. This type of quad-supercell metamaterial offers the advantage of enabling access to all the three distinct resonance features of the split-ring resonator, which consists of two odd eigenmodes in addition to the high-Q even eigenmode, which could be exploited for high performance multiband filters and absorbers. The high Q even eigenmode could find applications in designing label free bio-sensors and for studying the enhanced light matter interaction effects.

  15. Tunable Resonant Scanners

    NASA Astrophysics Data System (ADS)

    Montagu, Jean I.

    1987-01-01

    The most attractive features of resonant scanners are high reliability and eternal life as well as extremely low wobble and jitter. Power consumption is also low, electronic drive is simple, and the device is capable of handling large beams. All of these features are delivered at a low cost in a small package. The resonant scanner's use in numerous high precision applications, however, has been limited because of the difficulty in controlling its phase and resonant frequency. This paper introduces the concept of tunable/controllable resonant scanners, discusses their features, and offers a number of tuning techniques. It describes two angular scanner designs and presents data on tunable range and life tests. It also reviews applications for these new tunable resonant scanners that preserve the desirable features of earlier models while removing the old problems with synchronization or time base flexibility. The three major types of raster scanning applications where the tunable resonant scanner may be of benefit are: 1. In systems with multiple time bases such as multiple scanner networks or with scanners keyed to a common clock (the line frequency or data source) or a machine with multiple resonant scanners. A typical application is image and text transmission, also a printer with a large data base where a buffer is uneconomical. 2. In systems sharing data processing or laser equipment for reasons of cost or capacity, typically multiple work station manufacturing processes or graphic processes. 3. In systems with extremely precise time bases where the frequency stability of conventional scanners cannot be relied upon.

  16. Structural evidence for electromagnetic resonance in plant morphogenesis.

    PubMed

    Pietak, Alexis Mari

    2012-09-01

    How a homogeneous collective of cells consistently and precisely establishes long-range tissue patterns remains a question of active research. This work explores the hypothesis of plant organs as resonators for electromagnetic radiation. Long-range structural patterns in the developing ovaries and male flower buds of cucurbit plants (zucchini, acorn, and butternut squash), in addition to mature cucurbit fruits (acorn, butternut, and zucchini squash; watermelon, and cucumber), were investigated. A finite element analysis (FEA) model was used to determine resonant EM modes for models with similar geometric and electrical parameters to those of developing organs. Main features of the developing ovaries (i.e. shape of placental lines, ovum location, definition of distinct tissue regions), male flower buds (i.e. early pollen tube features), and mature fruits (i.e. septa placement, seed location, endocarp and mesocarp) showed distinct correlations with electric and magnetic field components of electromagnetic resonant modes. On account of shared pattern signatures in developing organs and the EM resonant modes supported by a modelled structure with similar geometric and electrical properties to those of cucurbit organs, experimental investigations are warranted. The concept of a developing organ as an EM dielectric resonator may extend to a variety of morphogenetic phenomena in a number of living systems. PMID:22326259

  17. Graphene-based waveguide resonators for submillimeter-wave applications

    NASA Astrophysics Data System (ADS)

    Ilić, Andjelija Ž.; Bukvić, Branko; Ilić, Milan M.; Budimir, Djuradj

    2016-08-01

    Utilization of graphene covered waveguide inserts to form tunable waveguide resonators is theoretically explained and rigorously investigated by means of full-wave numerical electromagnetic simulations. Instead of using graphene-based switching elements, the concept we propose incorporates graphene sheets as parts of a resonator. Electrostatic tuning of the graphene surface conductivity leads to changes in the electromagnetic field boundary conditions at the resonator edges and surfaces, thus producing an effect similar to varying the electrical length of a resonator. The presented outline of the theoretical background serves to give phenomenological insight into the resonator behavior, but it can also be used to develop customized software tools for design and optimization of graphene-based resonators and filters. Due to the linear dependence of the imaginary part of the graphene surface impedance on frequency, the proposed concept was expected to become effective for frequencies above 100 GHz, which is confirmed by the numerical simulations. A frequency range from 100 GHz up to 1100 GHz, where the rectangular waveguides are used, is considered. Simple, all-graphene-based resonators are analyzed first, to assess the achievable tunability and to check the performance throughout the considered frequency range. Graphene–metal combined waveguide resonators are proposed in order to preserve the excellent quality factors typical for the type of waveguide discontinuities used. Dependence of resonator properties on key design parameters is studied in detail. Dependence of resonator properties throughout the frequency range of interest is studied using eight different waveguide sections appropriate for different frequency intervals. Proposed resonators are aimed at applications in the submillimeter-wave spectral region, serving as the compact tunable components for the design of bandpass filters and other devices.

  18. Decoherence suppression in a resonant driving field

    NASA Astrophysics Data System (ADS)

    Minns, R. S.; Kutteruf, M. R.; Commisso, M. A.; Jones, R. R.

    2008-04-01

    Resonant radio frequency (rf) control fields have been employed to suppress decoherence in single quantum bits (qubits) encoded in the probability amplitudes of np fine-structure states in Li Rydberg atoms. As described previously [1], static electric-field tuning of the spin and orbital angular momentum composition of the fine-structure eigenstates enables qubit storage in an approximate decoherence-free subspace in which phase errors due to small stray electric and magnetic fields are strongly suppressed. In addition, it was found that sequences of short electric field pulses could be utilized in a 'bang-bang' dynamic decoupling scheme to improve coherence times. We now show that a continuous resonant rf field can also suppress decoherence in this system. The rf-dressed fine-structure states form a more robust basis in which the energy splitting between the component qubit levels is locked to the drive frequency, and decoherence is essentially eliminated. Measurements of the operational range of rf frequency and field strength required to achieve decoherence suppression are in agreement with the predictions of a two-level model.

  19. Resonant Raman scattering from silicon nanoparticles enhanced by magnetic response

    NASA Astrophysics Data System (ADS)

    Dmitriev, Pavel A.; Baranov, Denis G.; Milichko, Valentin A.; Makarov, Sergey V.; Mukhin, Ivan S.; Samusev, Anton K.; Krasnok, Alexander E.; Belov, Pavel A.; Kivshar, Yuri S.

    2016-05-01

    Enhancement of optical response with high-index dielectric nanoparticles is attributed to the excitation of their Mie-type magnetic and electric resonances. Here we study Raman scattering from crystalline silicon nanoparticles and reveal that magnetic dipole modes have a much stronger effect on the scattering than electric modes of the same order. We demonstrate experimentally a 140-fold enhancement of the Raman signal from individual silicon spherical nanoparticles at the magnetic dipole resonance. Our results confirm the importance of the optically-induced magnetic response of subwavelength dielectric nanoparticles for enhancing light-matter interactions.Enhancement of optical response with high-index dielectric nanoparticles is attributed to the excitation of their Mie-type magnetic and electric resonances. Here we study Raman scattering from crystalline silicon nanoparticles and reveal that magnetic dipole modes have a much stronger effect on the scattering than electric modes of the same order. We demonstrate experimentally a 140-fold enhancement of the Raman signal from individual silicon spherical nanoparticles at the magnetic dipole resonance. Our results confirm the importance of the optically-induced magnetic response of subwavelength dielectric nanoparticles for enhancing light-matter interactions. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07965a

  20. Reconfigurable Optical Spectra from Perturbations on Elliptical Whispering Gallery Resonances

    NASA Technical Reports Server (NTRS)

    Mohageg, Makan; Maleki, Lute

    2008-01-01

    Elastic strain, electrical bias, and localized geometric deformations were applied to elliptical whispering-gallery-mode resonators fabricated with lithium niobate. The resultant perturbation of the mode spectrum is highly dependant on the modal indices, resulting in a discretely reconfigurable optical spectrum. Breaking of the spatial degeneracy of the whispering-gallery modes due to perturbation is also observed.

  1. Reconfigurable optical spectra from perturbations on elliptical whispering gallery resonances.

    PubMed

    Mohageg, Makan; Maleki, Lute

    2008-02-01

    Elastic strain, electrical bias, and localized geometric deformations were applied to elliptical whispering-gallery-mode resonators fabricated with lithium niobate. The resultant perturbation of the mode spectrum is highly dependant on the modal indices, resulting in a discretely reconfigurable optical spectrum. Breaking of the spatial degeneracy of the whispering-gallery modes due to perturbation is also observed. PMID:18542283

  2. Mechanic-Like Resonance in the Maxwell-Bloch Equations

    ERIC Educational Resources Information Center

    Meziane, Belkacem

    2008-01-01

    We show that, in their unstable regime of operation, the "Maxwell-Bloch" equations that describe light-matter interactions inside a bad-cavity-configured laser carry the same resonance properties as any externally driven mechanic or electric oscillator. This finding demonstrates that the nonlinearly coupled laser equations belong to the same…

  3. Magnetic resonances in nano-scale metamaterials

    NASA Astrophysics Data System (ADS)

    Hao, Zhao; Liddle, Alex; Martin, Michael

    2006-03-01

    We have designed, fabricated, and optically measured several different kinds of nano-scale metamaterials. We make use e-beam nano-lithography technology at LBNL's Center for X-Ray Optics for fabricating these structures on extremely thin SiN substrates so that they are close to free-standing. Optical properties were measured as a function of incidence angle and polarization. We directly observe a strong magnetic resonance consistent with a negative magnetic permeability in our samples at mid- and near-IR optical frequencies. We will discuss the results in comparison with detailed simulations, and will discuss the electric dipole or quadrupole resonances observed in the samples. Finally, we will report on our progress towards constructing a fully negative index of refraction meta-material.

  4. Artificial Excitation of Schumann Resonance with HAARP

    NASA Astrophysics Data System (ADS)

    Streltsov, A. V.; Chang, C. L.

    2014-12-01

    We report results from the experiment aimed at the artificial excitation of extremely-low-frequency (ELF) electromagnetic waves with frequencies corresponding to the frequency of Schumann resonance (typically, 7.5 - 8.0 Hz frequency range). Electromagnetic waves with these frequencies can form a standing pattern inside the spherical cavity formed by the surface of the earth and the ionosphere. In the experiment the ELF waves were excited by heating the ionosphere with X-mode HF electromagnetic waves generated by the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. The experiment demonstrates that heating of the ionosphere can excite relatively large-amplitude electromagnetic waves with frequencies in the range of the Schumann resonance, when the ionosphere has a strong F-layer and an electric field greater than 5 mV/m is present in the E-region.

  5. Nuclear quadrupole resonance single-pulse echoes.

    PubMed

    Prescott, David W; Miller, Joel B; Tourigny, Chris; Sauer, Karen L

    2008-09-01

    We report the first detection of a spin echo after excitation of a powder sample by a single pulse at the resonance frequency during nuclear quadrupole resonance (NQR). These echoes can occur in samples that have an inhomogeneously broadened line, in this case due to the distribution of electric field gradients. The echoes are easily detectable when the Rabi frequency approaches the linewidth and the average effective tipping angle is close to 270 degrees. When limited by a weak radio-frequency field, the single-pulse echo can be used to increase the signal to noise ratio over conventional techniques. These effects can be used to optimize the NQR detection of contraband containing quadrupole nuclei and they are demonstrated with glycine hemihydrochloride and hexhydro-1,3,5-trinitro-1,3,5-triazine (RDX). PMID:18571445

  6. Resonant ultrasound spectrometer

    DOEpatents

    Migliori, Albert; Visscher, William M.; Fisk, Zachary

    1990-01-01

    An ultrasound resonant spectrometer determines the resonant frequency spectrum of a rectangular parallelepiped sample of a high dissipation material over an expected resonant response frequency range. A sample holder structure grips corners of the sample between piezoelectric drive and receive transducers. Each transducer is mounted on a membrane for only weakly coupling the transducer to the holder structure and operatively contacts a material effective to remove system resonant responses at the transducer from the expected response range. i.e., either a material such as diamond to move the response frequencies above the range or a damping powder to preclude response within the range. A square-law detector amplifier receives the response signal and retransmits the signal on an isolated shield of connecting cabling to remove cabling capacitive effects. The amplifier also provides a substantially frequency independently voltage divider with the receive transducer. The spectrometer is extremely sensitive to enable low amplitude resonance to be detected for use in calculating the elastic constants of the high dissipation sample.

  7. MACHINERY RESONANCE AND DRILLING

    SciTech Connect

    Leishear, R.; Fowley, M.

    2010-01-23

    New developments in vibration analysis better explain machinery resonance, through an example of drill bit chattering during machining of rusted steel. The vibration of an operating drill motor was measured, the natural frequency of an attached spring was measured, and the two frequencies were compared to show that the system was resonant. For resonance to occur, one of the natural frequencies of a structural component must be excited by a cyclic force of the same frequency. In this case, the frequency of drill bit chattering due to motor rotation equaled the spring frequency (cycles per second), and the system was unstable. A soft rust coating on the steel to be drilled permitted chattering to start at the drill bit tip, and the bit oscillated on and off of the surface, which increased the wear rate of the drill bit. This resonant condition is typically referred to as a motor critical speed. The analysis presented here quantifies the vibration associated with this particular critical speed problem, using novel techniques to describe resonance.

  8. Resonances in Positronium Hydride

    NASA Technical Reports Server (NTRS)

    Drachman, Richard J.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    Recently, Ho and his colleagues have calculated the positions and widths of a series of resonances in the Ps+H scattering system, using the complex -rotation method and have compared them with estimates that I made many years ago using a quite different technique. I assumed that the resonance mechanism was the existence in the rearrangement channel [e+ + H-] of an infinite series of perturbed Coulomb bound states. Although these must be broadened and shifted by coupling with the open scattering channel, I expected them to lie very close to the actual resonance positions. To verify this, I did a model calculation for S-waves, including the coupling, and found that the first two resonances were not shifted very far from their unperturbed position. The new, detailed calculation agrees with this result, but when the P-wave was examined it was found, surprisingly, that the lowest resonance indeed moved up in energy by a large amount. With the help of Joseph DiRienzi of the College of Notre Dame of Maryland I am now extending the old calculation to P- and D-waves, in an attempt to understand this unexpected energy shift. Results will be presented at the Workshop.

  9. Fluctuation Reduction in a Si Micromechanical Resonator Tuned to Nonlinear Internal Resonance

    NASA Astrophysics Data System (ADS)

    Strachan, B. Scott; Czaplewski, David; Chen, Changyao; Dykman, Mark; Lopez, Daniel; Shaw, Steven

    2015-03-01

    We describe experimental and theoretical results on an unusual behavior of fluctuations when the system exhibits internal resonance. We study the fundamental flexural mode (FFM) of a Si microbeam. The FFM is electrically actuated and detected. It is resonantly nonlinearly coupled to another mode, which is not directly accessible and has a frequency nearly three times the FFM frequency. Both the FFM and the passive mode have long lifetimes. We find that the passive mode can be a ``sink'' for fluctuations of the FFM. This explains the recently observed dramatic decrease of these fluctuations at nonlinear resonance. The re-distribution of the vibration amplitudes and the fluctuations is reminiscent of what happens at level anti-crossing in quantum mechanics. However, here it is different because of interplay of the dependence of the vibration frequency of the FFM on its amplitude due to internal nonlinearity and the nonlinear resonance with the passive mode. We study both the response of the system to external resonant driving and also the behavior of the system in the presence of a feedback loop. The experimental and theoretical results are in good agreement.

  10. High Q calcium titanate cylindrical dielectric resonators for magnetic resonance microimaging.

    PubMed

    Haines, K; Neuberger, T; Lanagan, M; Semouchkina, E; Webb, A G

    2009-10-01

    At high magnetic fields radiation losses, wavelength effects, self-resonance, and the high resistance of typical components all contribute to increased losses in conventional RF coil designs. High permittivity ceramic dielectric resonators create strong uniform magnetic fields in a compact structure at high frequencies and can potentially solve some of the challenges of high field coil design. In this study an NMR probe was constructed for operation at 600 MHz (14.1T) using an inductively fed CaTiO(3) (relative permittivity of 156) cylindrical hollow bore dielectric resonator. The design has an unmatched Q value greater than 2000, and the electric field is largely confined to the dielectric itself, with near zero values in the hollow bore which accommodates the sample. Experimental and simulation mapping of the RF field show good agreement, with the ceramic resonator giving a pulse width approximately 25% less than a loop gap resonator of similar inner dimensions. High resolution images, with voxel dimensions less than 50 microm(3), have been acquired from fixed zebrafish samples, showing excellent delineation of several fine structures. PMID:19656696

  11. High Q calcium titanate cylindrical dielectric resonators for magnetic resonance microimaging

    NASA Astrophysics Data System (ADS)

    Haines, K.; Neuberger, T.; Lanagan, M.; Semouchkina, E.; Webb, A. G.

    2009-10-01

    At high magnetic fields radiation losses, wavelength effects, self-resonance, and the high resistance of typical components all contribute to increased losses in conventional RF coil designs. High permittivity ceramic dielectric resonators create strong uniform magnetic fields in a compact structure at high frequencies and can potentially solve some of the challenges of high field coil design. In this study an NMR probe was constructed for operation at 600 MHz (14.1 T) using an inductively fed CaTiO 3 (relative permittivity of 156) cylindrical hollow bore dielectric resonator. The design has an unmatched Q value greater than 2000, and the electric field is largely confined to the dielectric itself, with near zero values in the hollow bore which accommodates the sample. Experimental and simulation mapping of the RF field show good agreement, with the ceramic resonator giving a pulse width approximately 25% less than a loop gap resonator of similar inner dimensions. High resolution images, with voxel dimensions less than 50 μm 3, have been acquired from fixed zebrafish samples, showing excellent delineation of several fine structures.

  12. A microring resonator based negative permeability metamaterial sensor.

    PubMed

    Sun, Jun; Huang, Ming; Yang, Jing-Jing; Li, Ting-Hua; Lan, Yao-Zhong

    2011-01-01

    Metamaterials are artificial multifunctional materials that acquire their material properties from their structure, rather than inheriting them directly from the materials they are composed of, and they may provide novel tools to significantly enhance the sensitivity and resolution of sensors. In this paper, we derive the dispersion relation of a cylindrical dielectric waveguide loaded on a negative permeability metamaterial (NPM) layer, and compute the resonant frequencies and electric field distribution of the corresponding Whispering-Gallery-Modes (WGMs). The theoretical resonant frequency and electric field distribution results are in good agreement with the full wave simulation results. We show that the NPM sensor based on a microring resonator possesses higher sensitivity than the traditional microring sensor since with the evanescent wave amplification and the increase of NPM layer thickness, the sensitivity will be greatly increased. This may open a door for designing sensors with specified sensitivity. PMID:22164062

  13. Solar Electricity

    NASA Technical Reports Server (NTRS)

    1988-01-01

    ARCO Solar manufactures PV Systems tailored to a broad variety of applications. PV arrays are routinely used at remote communications installations to operate large microwave repeaters, TV and radio repeaters rural telephone, and small telemetry systems that monitor environmental conditions. Also used to power agricultural water pumping systems, to provide electricity for isolated villages and medical clinics, for corrosion protection for pipelines and bridges, to power railroad signals, air/sea navigational aids, and for many types of military systems. ARCO is now moving into large scale generation for utilities.

  14. Electrical receptacle

    DOEpatents

    Leong, Robert

    1993-01-01

    The invention is a receptacle for a three prong electrical plug which has either a tubular or U-shaped grounding prong. The inventive receptacle has a grounding prong socket which is sufficiently spacious to prevent the socket from significantly stretching when a larger, U-shaped grounding prong is inserted into the socket, and having two ridges to allow a snug fit when a smaller tubular shape grounding prong is inserted into the socket. The two ridges are made to prevent the socket from expanding when either the U-shaped grounding prong or the tubular grounding prong is inserted.

  15. Electrical receptacle

    DOEpatents

    Leong, R.

    1993-06-22

    The invention is a receptacle for a three prong electrical plug which has either a tubular or U-shaped grounding prong. The inventive receptacle has a grounding prong socket which is sufficiently spacious to prevent the socket from significantly stretching when a larger, U-shaped grounding prong is inserted into the socket, and having two ridges to allow a snug fit when a smaller tubular shape grounding prong is inserted into the socket. The two ridges are made to prevent the socket from expanding when either the U-shaped grounding prong or the tubular grounding prong is inserted.

  16. Electrical machine

    DOEpatents

    De Bock, Hendrik Pieter Jacobus; Alexander, James Pellegrino; El-Refaie, Ayman Mohamed Fawzi; Gerstler, William Dwight; Shah, Manoj Ramprasad; Shen, Xiaochun

    2016-06-21

    An apparatus, such as an electrical machine, is provided. The apparatus can include a rotor defining a rotor bore and a conduit disposed in and extending axially along the rotor bore. The conduit can have an annular conduit body defining a plurality of orifices disposed axially along the conduit and extending through the conduit body. The rotor can have an inner wall that at least partially defines the rotor bore. The orifices can extend through the conduit body along respective orifice directions, and the rotor and conduit can be configured to provide a line of sight along the orifice direction from the respective orifices to the inner wall.

  17. Collider Signal I :. Resonance

    NASA Astrophysics Data System (ADS)

    Tait, Tim M. P.

    2010-08-01

    These TASI lectures were part of the summer school in 2008 and cover the collider signal associated with resonances in models of physics beyond the Standard Model. I begin with a review of the Z boson, one of the best-studied resonances in particle physics, and review how the Breit-Wigner form of the propagator emerges in perturbation theory and discuss the narrow width approximation. I review how the LEP and SLAC experiments could use the kinematics of Z events to learn about fermion couplings to the Z. I then make a brief survey of models of physics beyond the Standard Model which predict resonances, and discuss some of the LHC observables which we can use to discover and identify the nature of the BSM physics. I finish up with a discussion of the linear moose that one can use for an effective theory description of a massive color octet vector particle.

  18. Three-pion resonances

    NASA Astrophysics Data System (ADS)

    Garcilazo, H.; Mathelitsch, L.

    1994-03-01

    We investigate the continuum three-pion problem within a relativistic three-body model that takes into account the ππ S and P waves. The dynamical input of the two-body subsystem is given by separable potentials, which yield a good fit to the ππ scattering data and resonance parameters up to a two-body invariant mass of 900MeV. We introduce a parameter ν expressing the ambiguity in the reduction of a fully relativistic theory to a three-dimensional one. The masses and widths of the ω, a 1(1260), and π(1300) mesons, which decay predominantly into three pions, are reasonably well described by our model. The h 1(1170) meson, however, which also decays into three pions, cannot be explained as a three-pion resonance. Some πρ Argand diagrams are shown in those channels where resonances exist.

  19. Quartz resonator processing system

    DOEpatents

    Peters, Roswell D. M.

    1983-01-01

    Disclosed is a single chamber ultra-high vacuum processing system for the oduction of hermetically sealed quartz resonators wherein electrode metallization and sealing are carried out along with cleaning and bake-out without any air exposure between the processing steps. The system includes a common vacuum chamber in which is located a rotatable wheel-like member which is adapted to move a plurality of individual component sets of a flat pack resonator unit past discretely located processing stations in said chamber whereupon electrode deposition takes place followed by the placement of ceramic covers over a frame containing a resonator element and then to a sealing stage where a pair of hydraulic rams including heating elements effect a metallized bonding of the covers to the frame.

  20. Magnetostrictive resonance excitation

    DOEpatents

    Schwarz, Ricardo B.; Kuokkala, Veli-Tapani

    1992-01-01

    The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection coil varies with the strain in the material whereby resonance responses of the sample can be readily detected. A suitable sample may be a magnetostrictive material or some other material having at least one side coated with a magnetostrictive material. When the sample is a suitable shape, i.e., a cube, rectangular parallelepiped, solid sphere or spherical shell, the elastic moduli or the material can be analytically determined from the measured resonance frequency spectrum. No mechanical transducers are required and the sample excitation is obtained without contact with the sample, leading to highly reproducible results and a measurement capability over a wide temperature range, e.g. from liquid nitrogen temperature to the Curie temperature of the magnetostrictive material.

  1. Physics of Sports: Resonances

    NASA Astrophysics Data System (ADS)

    Browning, David

    2000-04-01

    When force is applied by an athlete to sports equipment resonances can occur. Just a few examples are: the ringing of a spiked volleyball, the strumming of a golf club shaft during a swing, and multiple modes induced in an aluminum baseball bat when striking a ball. Resonances produce acoustic waves which, if conditions are favorable, can be detected off the playing field. This can provide a means to evaluate athletic performance during game conditions. Results are given from the use of a simple hand-held acoustic detector - by a spectator sitting in the stands - to determine how hard volleyballs were spiked during college and high school games.

  2. Method for resonant measurement

    DOEpatents

    Rhodes, G.W.; Migliori, A.; Dixon, R.D.

    1996-03-05

    A method of measurement of objects to determine object flaws, Poisson`s ratio ({sigma}) and shear modulus ({mu}) is shown and described. First, the frequency for expected degenerate responses is determined for one or more input frequencies and then splitting of degenerate resonant modes are observed to identify the presence of flaws in the object. Poisson`s ratio and the shear modulus can be determined by identification of resonances dependent only on the shear modulus, and then using that shear modulus to find Poisson`s ratio using other modes dependent on both the shear modulus and Poisson`s ratio. 1 fig.

  3. Magnetic resonance annual, 1988

    SciTech Connect

    Kressel, H.Y.

    1987-01-01

    This book features reviews of high-resolution MRI of the knee, MRI of the normal and ischmeic hip, MRI of the heart, and temporomandibular joint imaging, as well as thorough discussion on artifacts in magnetic resonance imaging. Contributors consider the clinical applications of gadolinium-DTPA in magnetic resonance imaging and the clinical use of partial saturation and saturation recovery sequences. Timely reports assess the current status of rapid MRI and describe a new rapid gated cine MRI technique. Also included is an analysis of cerebrospinal fluid flow effects during MRI of the central nervous system.

  4. Pygmy resonances and nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Tsoneva, Nadia; Lenske, Horst

    2015-05-01

    A microscopic theoretical approach based on a self-consistent density functional theory for the nuclear ground state and QRPA formalism extended with multi-phonon degrees of freedom for the nuclear excited states is implemented in investigations of new low-energy modes called pygmy resonances. Advantage of the method is the unified description of low-energy multiphonon excitations, pygmy resonances and core polarization effects. This is found of crucial importance for the understanding of the fine structure of nuclear response functions at low energies. Aspects of the precise knowledge of nuclear response functions around the neutron threshold are discussed in a connection to nucleosynthesis.

  5. Method for resonant measurement

    DOEpatents

    Rhodes, George W.; Migliori, Albert; Dixon, Raymond D.

    1996-01-01

    A method of measurement of objects to determine object flaws, Poisson's ratio (.sigma.) and shear modulus (.mu.) is shown and described. First, the frequency for expected degenerate responses is determined for one or more input frequencies and then splitting of degenerate resonant modes are observed to identify the presence of flaws in the object. Poisson's ratio and the shear modulus can be determined by identification of resonances dependent only on the shear modulus, and then using that shear modulus to find Poisson's ratio using other modes dependent on both the shear modulus and Poisson's ratio.

  6. Field resonance propulsion concept

    NASA Technical Reports Server (NTRS)

    Holt, A. C.

    1979-01-01

    A propulsion concept was developed based on a proposed resonance between coherent, pulsed electromagnetic wave forms, and gravitational wave forms (or space-time metrics). Using this concept a spacecraft propulsion system potentially capable of galactic and intergalactic travel without prohibitive travel times was designed. The propulsion system utilizes recent research associated with magnetic field line merging, hydromagnetic wave effects, free-electron lasers, laser generation of megagauss fields, and special structural and containment metals. The research required to determine potential, field resonance characteristics and to evaluate various aspects of the spacecraft propulsion design is described.

  7. Hexagonal quartz resonator

    DOEpatents

    Peters, R.D.M.

    1982-11-02

    A generally flat, relatively thin AT-cut piezoelectric resonator element structured to minimize the force-frequency effect when mounted and energized in a housing. The resonator is in the form of an equilateral hexagon with the X crystallographic axis of the crystal passing through one set of opposing corners with mounting being effected at an adjacent set of corners respectively [+-]60[degree] away from the X axis which thereby results in a substantially zero frequency shift of the operating frequency. 3 figs.

  8. Resonant optical gun.

    PubMed

    Maslov, A V; Bakunov, M I

    2014-05-01

    We propose a concept of a structure-a resonant optical gun-to realize an efficient propulsion of dielectric microparticles by light forces. The structure is based on a waveguide in which a reversal of the electromagnetic momentum flow of the incident mode is realized by exciting a whispering gallery resonance in the microparticle. The propelling force can reach the value up to the theoretical maximum of twice the momentum flow of the initial wave. The force density oscillates along the particle periphery and has very large amplitude. PMID:24784113

  9. Optical Fano resonances in a nonconcentric nanoshell.

    PubMed

    Norton, Stephen J; Vo-Dinh, Tuan

    2016-04-01

    The interaction of light with a metal nanoshell with an off-center core generates multipoles of all orders. We show here that the matrix elements used to compute the multipole expansion coefficients can be derived analytically and, with this result, we can show explicitly how the dipole and quadrupole terms in the expansion are coupled and give rise to a Fano resonance. We also show that the off-center core significantly increases the electric field enhancement at the shell surface compared to the concentric case, which can be exploited for surface-enhanced sensing. The multipole solutions are confirmed with finite-element calculations. PMID:27139663

  10. Strong-Field Resonant Dynamics in Semiconductors

    NASA Astrophysics Data System (ADS)

    Wismer, Michael S.; Kruchinin, Stanislav Yu.; Ciappina, Marcelo; Stockman, Mark I.; Yakovlev, Vladislav S.

    2016-05-01

    We predict that a direct band gap semiconductor (GaAs) resonantly excited by a strong ultrashort laser pulse exhibits a novel regime: kicked anharmonic Rabi oscillations. In this regime, Rabi oscillations are strongly coupled to intraband motion, and interband transitions mainly take place when electrons pass near the Brillouin zone center where electron populations undergo very rapid changes. The asymmetry of the residual population distribution induces an electric current controlled by the carrier-envelope phase of the driving pulse. The predicted effects are experimentally observable using photoemission and terahertz spectroscopies.

  11. Strong-Field Resonant Dynamics in Semiconductors.

    PubMed

    Wismer, Michael S; Kruchinin, Stanislav Yu; Ciappina, Marcelo; Stockman, Mark I; Yakovlev, Vladislav S

    2016-05-13

    We predict that a direct band gap semiconductor (GaAs) resonantly excited by a strong ultrashort laser pulse exhibits a novel regime: kicked anharmonic Rabi oscillations. In this regime, Rabi oscillations are strongly coupled to intraband motion, and interband transitions mainly take place when electrons pass near the Brillouin zone center where electron populations undergo very rapid changes. The asymmetry of the residual population distribution induces an electric current controlled by the carrier-envelope phase of the driving pulse. The predicted effects are experimentally observable using photoemission and terahertz spectroscopies. PMID:27232043

  12. Electrically tunable infrared metamaterial devices

    DOEpatents

    Brener, Igal; Jun, Young Chul

    2015-07-21

    A wavelength-tunable, depletion-type infrared metamaterial optical device is provided. The device includes a thin, highly doped epilayer whose electrical permittivity can become negative at some infrared wavelengths. This highly-doped buried layer optically couples with a metamaterial layer. Changes in the transmission spectrum of the device can be induced via the electrical control of this optical coupling. An embodiment includes a contact layer of semiconductor material that is sufficiently doped for operation as a contact layer and that is effectively transparent to an operating range of infrared wavelengths, a thin, highly doped buried layer of epitaxially grown semiconductor material that overlies the contact layer, and a metallized layer overlying the buried layer and patterned as a resonant metamaterial.

  13. Nuclear magnetic resonance imaging in patients with cardiac pacing devices.

    PubMed

    Buendía, Francisco; Sánchez-Gómez, Juan M; Sancho-Tello, María J; Olagüe, José; Osca, Joaquín; Cano, Oscar; Arnau, Miguel A; Igual, Begoña

    2010-06-01

    Currently, nuclear magnetic resonance imaging is contraindicated in patients with a pacemaker or implantable cardioverter-defibrillator. This study was carried out because the potential risks in this situation need to be clearly defined. This prospective study evaluated clinical and electrical parameters before and after magnetic resonance imaging was performed in 33 patients (five with implantable cardioverter-defibrillators and 28 with pacemakers). In these patients, magnetic resonance imaging was considered clinically essential. There were no clinical complications. There was a temporary communication failure in two cases, sensing errors during imaging in two cases, and a safety signal was generated in one pacemaker at the maximum magnetic resonance frequency and output level. There were no technical restrictions on imaging nor were there any permanent changes in the performance of the cardiac pacing device. PMID:20515632

  14. High-sensitivity linear piezoresistive transduction for nanomechanical beam resonators.

    PubMed

    Sansa, Marc; Fernández-Regúlez, Marta; Llobet, Jordi; San Paulo, Álvaro; Pérez-Murano, Francesc

    2014-01-01

    Highly sensitive conversion of motion into readable electrical signals is a crucial and challenging issue for nanomechanical resonators. Efficient transduction is particularly difficult to realize in devices of low dimensionality, such as beam resonators based on carbon nanotubes or silicon nanowires, where mechanical vibrations combine very high frequencies with miniscule amplitudes. Here we describe an enhanced piezoresistive transduction mechanism based on the asymmetry of the beam shape at rest. We show that this mechanism enables highly sensitive linear detection of the vibration of low-resistivity silicon beams without the need of exceptionally large piezoresistive coefficients. The general application of this effect is demonstrated by detecting multiple-order modes of silicon nanowire resonators made by either top-down or bottom-up fabrication methods. These results reveal a promising approach for practical applications of the simplest mechanical resonators, facilitating its manufacturability by very large-scale integration technologies. PMID:25000256

  15. Resonant and Ground Experimental Study on the Microwave Plasma Thruster

    NASA Astrophysics Data System (ADS)

    Yang, Juan; He, Hongqing; Mao, Genwang; Qu, Kun; Tang, Jinlan; Han, Xianwei

    2002-01-01

    chemistry. Therefore, the application of EP for the attitude control and station keeping of satellite, the propulsion of deep space exploration craft allows to reduce substantially the mass of on-board propellant and the launching cost. The EP research is now receiving high interest everywhere. microwave generating subsystem, the propellant supplying subsystem and the resonator (the thruster). Its principle is that the magnetron of the microwave generating subsystem transfers electric energy into microwave energy at given frequency which is introduced into a resonant cavity. Microwave will resonate within the cavity when it is adjusted. When the propellant gas (N2, Ar, He, NH3 or H2) is put into the cavity and coupled with microwave energy at the maximal electric intensity place, it will be broken down to form free-floating plasma, which flows from nozzle with high speed to produce thrust. Its characteristic is high efficiency, simple power supply and without electrode ablation, its specific impulse is greater than arcjet. 2450MHz, have been developed. The microwave generating subsystem and resonator of lower power MPT, 70-200W, are coaxial. The resonator with TEM resonating mode is section of coaxial wave-guide, of which one end is shorted, another is semi-opened. The maximal electric intensity field is in the lumped capacity formed between the end surface of inner conductor, retracting in the cavity, and the semi-opened surface of outer conductor. It provides favorable condition for gas breakdown. The microwave generating system and resonator of middle power MPT, 500-1,000W, are wave-guide cavity. The resonator with TM011 resonating mode is cylinder wave-guide cavity, of which two end surface are shorted. The distribution of electromagnetic field is axial symmetry, its maximal electric intensity field locates on the axis and closes to the exit of nozzle, where the propellant gas is breakdown to form free floating plasma. The plasma is free from the wall of

  16. Degenerate band edge resonances in periodic silicon ridge waveguides.

    PubMed

    Wood, Michael G; Burr, Justin R; Reano, Ronald M

    2015-06-01

    We experimentally demonstrate degenerate band edge resonances in periodic Si ridge waveguides that are compatible with carrier injection modulation for active electro-optical devices. The resonant cavities are designed using a combination of the plane-wave expansion method and the finite difference time domain technique. Measured and simulated quality factors of the first band edge resonances scale to the fifth power of the number of periods. Quality factor scaling is determined to be limited by fabrication imperfections. Compared to resonators based on a regular transmission band edge, degenerate band edge devices can achieve significantly larger quality factors in the same number of periods. Applications include compact electro-optical switches, modulators, and sensors that benefit from high-quality factors and large distributed electric fields. PMID:26030540

  17. Black phosphorus nanoelectromechanical resonators vibrating at very high frequencies.

    PubMed

    Wang, Zenghui; Jia, Hao; Zheng, Xuqian; Yang, Rui; Wang, Zefang; Ye, G J; Chen, X H; Shan, Jie; Feng, Philip X-L

    2015-01-21

    We report on the experimental demonstration of a new type of nanoelectromechanical resonator based on black phosphorus crystals. Facilitated by a highly efficient dry transfer technique, crystalline black phosphorus flakes are harnessed to enable drumhead resonators vibrating at high and very high frequencies (HF and VHF bands, up to ∼100 MHz). We investigate the resonant vibrational responses from the black phosphorus crystals by devising both electrical and optical excitation schemes, in addition to measuring the undriven thermomechanical motions in these suspended nanostructures. Flakes with thicknesses from ∼200 nm down to ∼20 nm clearly exhibit elastic characteristics transitioning from the plate to the membrane regime. Both frequency- and time-domain measurements of the nanomechanical resonances show that very thin black phosphorus crystals hold interesting potential for moveable and vibratory devices and for semiconductor transducers where high-speed mechanical motions could be coupled to the attractive electronic and optoelectronic properties of black phosphorus. PMID:25385657

  18. Basic Electricity. Part 2.

    ERIC Educational Resources Information Center

    Kilmer, Donald C.

    This guide, the second (part 2) in a set of four guides, is designed for the student interested in a vocation in electrical work, and includes two units: Unit IV--Electrical Theory, covering thirteen lessons (matter, the atom, electrical charges in the atom, rules of electric charges, electricity, atoms in an electrical conductor, electrical…

  19. Theory of Resonance Influence of Sawtooth Crashes on Ions with Large Orbit Width

    SciTech Connect

    R.B. White; V.V. Lutsenko; Y.I. Kolesnichenko; Y.V. Yakovenko

    1998-02-01

    The role of resonances in the sawtooth-crash-induced redistribution of fast ions is investigated. In particular, the conditions of wave-particle resonant interaction in the presence of the equilibrium electric field and the mode rotation are obtained, and effects of sawteeth on the resonant particles with arbitrary width of non-perturbed orbits are studied. It is found that resonances play the dominant role in the transport of ions having sufficiently high energy. It is shown that the resonance regions may overlap, in which case the resonant particles may constitute the main fraction of the fast ion population in the sawtooth mixing region. The behavior of the resonant particles is studied both by constructing a Poincaré map and analytically, by means of the adiabatic invariant derived in this paper and calculation of the characteristic frequencies of the particle motion.

  20. Electric thruster models for multimegawatt nuclear electric propulsion mission design

    SciTech Connect

    Leifer, S.D.; Blandino, J.J.; Sercel, J.C. )

    1991-01-05

    Three types of electric thrusters currently under development at JPL have potential to support future missions which utilize multimegawatt nuclear electric propulsion. These electric thrusters are the electron bombardment ion thruster, the magnetoplasmadynamic (MPD) thruster, and the electron-cyclotron-resonance (ECR) thruster. The electron bombardment ion thruster is a relatively mature technology which has been developed for operation at kilowatt power levels but will require new development for application in the multimegawatt regime. The MPD engine represents a technology which may be very well suited to steady-state multimegawatt applications but which has been limited to sub-scale (100's of kW) and pulsed (MW) testing thus far. The ECR plasma engine represents a class of very promising new concepts which are still in the basic research phase of development, but which may possess important fundamental advantages over other electric thruster technologies. In this paper, models of these thrusters are described and used to make projections of thruster specific mass, efficiency, and power handling capacity for operation in the multimegawatt regime.

  1. Electric thruster models for multimegawatt nuclear electric propulsion mission design

    NASA Technical Reports Server (NTRS)

    Leifer, Stephanie D.; Blandino, John J.; Sercel, Joel C.

    1991-01-01

    Three types of electric thrusters currently under development at JPL have potential to support future missions which utilize multimegawatt nuclear electric propulsion. These electric thrusters are the electron bombardment ion thruster, the magnetoplasmadynamic (MPD) thruster, and the electron-cyclotron-resonance (ECR) thruster. The electron bombardment ion thruster is a relatively mature technology which has been developed for operation at kilowatt power levels but will require new development for application in the multimegawatt regime. The MPD engine represents a technology which may be very well suited to steady-state multimegawatt applications but which has been limited to sub-scale (100's of kW) and pulsed (MW) testing thus far. The ECR plasma engine represents a class of very promising new concepts which are still in the basic research phase of development, but which may possess important fundamental advantages over other electric thruster technologies. Models of these thrusters are described and used to make projections of thrusters specific mass, efficiency, and power handling capacity for operation in the multimegawatt regime.

  2. Sub-wavelength Unidirectional Antenna Realized by Stacked Spoof Localized Surface Plasmon Resonators

    NASA Astrophysics Data System (ADS)

    Qin, Feifei; Zhang, Qiang; Xiao, Jun-Jun

    2016-07-01

    The use of resonant structures to control scattering strength and directionality is of importance in various electromagnetic systems. Here we propose and demonstrate sub-wavelength unidirectional scattering by two nearby spoof localized surface plasmon resonators for microwave. The principle is that metal surfaces corrugated by grooves can support magnetic dipolar modes, as well as electric dipolar modes. The resonance is essentially dictated by the geometric parameter of the structure, enabling extremely high degrees of freedom for tuning the scattering properties of the resonator. Particularly, by adjusting the thickness of the resonators, we can make the magnetic dipole mode of one resonator have nearly the same resonant frequency with that of the electric dipole mode of the other resonator. We show that nearly zero backscattering happens when the distance between the two resonators is subwavelenght but larger than a certain value, otherwise strong vertical coupling and mode splitting occur. The results can be extended to other frequency bands and might find application in unique resonant devices as a radio frequency (RF) antenna, filter and metasurface.

  3. Sub-wavelength Unidirectional Antenna Realized by Stacked Spoof Localized Surface Plasmon Resonators.

    PubMed

    Qin, Feifei; Zhang, Qiang; Xiao, Jun-Jun

    2016-01-01

    The use of resonant structures to control scattering strength and directionality is of importance in various electromagnetic systems. Here we propose and demonstrate sub-wavelength unidirectional scattering by two nearby spoof localized surface plasmon resonators for microwave. The principle is that metal surfaces corrugated by grooves can support magnetic dipolar modes, as well as electric dipolar modes. The resonance is essentially dictated by the geometric parameter of the structure, enabling extremely high degrees of freedom for tuning the scattering properties of the resonator. Particularly, by adjusting the thickness of the resonators, we can make the magnetic dipole mode of one resonator have nearly the same resonant frequency with that of the electric dipole mode of the other resonator. We show that nearly zero backscattering happens when the distance between the two resonators is subwavelenght but larger than a certain value, otherwise strong vertical coupling and mode splitting occur. The results can be extended to other frequency bands and might find application in unique resonant devices as a radio frequency (RF) antenna, filter and metasurface. PMID:27405356

  4. Sub-wavelength Unidirectional Antenna Realized by Stacked Spoof Localized Surface Plasmon Resonators

    PubMed Central

    Qin, Feifei; Zhang, Qiang; Xiao, Jun-Jun

    2016-01-01

    The use of resonant structures to control scattering strength and directionality is of importance in various electromagnetic systems. Here we propose and demonstrate sub-wavelength unidirectional scattering by two nearby spoof localized surface plasmon resonators for microwave. The principle is that metal surfaces corrugated by grooves can support magnetic dipolar modes, as well as electric dipolar modes. The resonance is essentially dictated by the geometric parameter of the structure, enabling extremely high degrees of freedom for tuning the scattering properties of the resonator. Particularly, by adjusting the thickness of the resonators, we can make the magnetic dipole mode of one resonator have nearly the same resonant frequency with that of the electric dipole mode of the other resonator. We show that nearly zero backscattering happens when the distance between the two resonators is subwavelenght but larger than a certain value, otherwise strong vertical coupling and mode splitting occur. The results can be extended to other frequency bands and might find application in unique resonant devices as a radio frequency (RF) antenna, filter and metasurface. PMID:27405356

  5. Effects of electromagnetic radiation on the Q of quartz resonators.

    PubMed

    Yong, Yook-Kong; Patel, Mihir; Vig, John; Ballato, Arthur

    2009-02-01

    The quartz resonator Q with aluminum electrodes was studied with respect to its fundamental thickness shear mode frequency and its viscoelastic, viscopiezoelectric, and viscopiezoelectromagnetic behaviors. The governing equations for viscoelasticity, viscopiezoelectricity, and viscopiezoelectromagnetism were implemented for an AT-cut quartz resonator. To simulate the radiation conditions at infinity for the viscopiezoelectromagnetic model, perfectly matched layers over a surface enclosing the resonator were implemented to absorb all incident electromagnetic radiation. The shape of the radiation spectrum of a 5.6 MHz AT-cut quartz resonator was found to compare relatively well the measured results by Campbell and Weber. The mesa-plate resonator was studied for a frequency range of 1.4 GHz to 3.4 GHz. The resonator Q was determined to be influenced predominantly by the quartz viscoelasticity; however at frequencies greater than 2.3 GHz, the quartz electromagnetic radiation had an increasingly significant effect on the resonator Q. At 3.4 GHz, the electromagnetic radiation accounted for about 14% of the loss in resonator Q. At frequencies less than 2 GHz, the calculated resonator Q compared well with the intrinsic Q(x) provided by the formula Q(x) = 16 x 10(6)/f where f was in MHz. At frequencies higher than 2.3 GHz, the aluminum electrodes had significant effects on the resonator Q. At 3.4 GHz, the electromagnetic radiation loss in the electrodes was an order of magnitude greater than their viscoelastic loss; hence, the vibrating aluminum electrodes became an efficient emitter of electromagnetic waves. The effects of electrical resistance in both the electrodes and quartz were determined to be negligible. PMID:19251522

  6. Quantum RLC circuits: Charge discreteness and resonance

    NASA Astrophysics Data System (ADS)

    Utreras-Díaz, Constantino A.

    2008-10-01

    In a recent article [C.A. Utreras-Díaz, Phys. Lett. A 372 (2008) 5059], we have advanced a semiclassical theory of quantum circuits with discrete charge and electrical resistance. In this work, we present a few elementary applications of this theory. For the zero resistance inductive circuit, we obtain the Stark ladder energies in yet another way; for the circuit driven by a combination d.c. plus a.c. electromotive force (emf) we generalize earlier results by Chandía et al. [K. Chandía, J.C. Flores, E. Lazo, Phys. Lett. A 359 (2006) 693]. As a second application, we investigate the effect of electrical resistance and charge discreteness, in the resonance conditions of a series RLC quantum circuit.

  7. Transmission properties of terahertz pulses through semiconductor split-ring resonators

    NASA Astrophysics Data System (ADS)

    yun-hong, He; Jiu-sheng, Li

    2011-02-01

    In this paper, two novel planar terahertz semiconductor split-ring resonators are successfully constructed and measured using the commercial software CST Microwave Studio. They exhibit a duel-band and a triple-band transmission property within the frequencies ranging from 0.1THz to 3THz. We have simulated the dual-band planar metamaterial with two distinct electric resonances at 0.81THz and 1.818THz, and triple-band planar metamaterial with three distinct electric resonances at 0.543THz, 1.044THz, and 1.506THz. These developments are further steps towards the development of broadband terahertz devices.

  8. Generation of plasma rotation by ion cyclotron resonance heating in tokamaks

    SciTech Connect

    Chang, C.S.; Phillips, C.K.; White, R.; Zweben, S.; Bonoli, P.T.; Rice, J.E.; Greenwald, M.J.; deGrassie, J.

    1999-05-01

    A physical mechanism for generation of a plasma rotation and radial electric field by ion cyclotron resonance heating (ICRH) is presented in a tokamak geometry. By breaking the omnigenity of resonant ion orbits, ICRH can induce a nonambipolar minor-radial transport of resonant ions. This yields a radial charge separation, a modification to radial electric field E{sub r}, and the generation of plasma rotation. It is estimated that the ICRH fast-wave power available in the present-day tokamak experiments can be large enough to give a significant modification to plasma rotation. {copyright} {ital 1999 American Institute of Physics.}

  9. Micromachined double resonator

    NASA Technical Reports Server (NTRS)

    Gutierrez, Roman (Inventor); Tang, Tony K. (Inventor); Shcheglov, Kirill (Inventor)

    2002-01-01

    A micromachined resonator mountable to an external support structure has a proof mass coupled to a base structure by a first spring structure, the base structure having a plurality of electrodes, and a second spring structure coupling the base structure to the external support structure.

  10. Magnetic resonance imaging

    SciTech Connect

    Stark, D.D.; Bradley, W.G. Jr.

    1988-01-01

    The authors present a review of magnetic resonance imaging. Many topics are explored from instrumentation, spectroscopy, blood flow and sodium imaging to detailed clinical applications such as the differential diagnosis of multiple sclerosis or adrenal adenoma. The emphasis throughout is on descriptions of normal multiplanar anatomy and pathology as displayed by MRI.

  11. Proton resonance spectroscopy

    SciTech Connect

    Shriner, J.F. Jr.

    1991-11-01

    This report discusses the following topics: Complete Level Scheme for {sup 30}P; A Search for Resonances Suitable for Tests of Detailed-Balance Violation; The Fourier Transform as a Tool for Detecting Chaos; Entrance Channel Correlations in p + {sup 27}Al; The Parity Dependence of Level Densities in {sup 49}V; and A Computer Program for the Calculation of Angular Momentum Coupling.

  12. Magnetic Resonance Annual, 1985

    SciTech Connect

    Kressel, H.Y.

    1985-01-01

    The inaugural volume of Magnetic Resonance Annual includes reviews of MRI of the posterior fossa, cerebral neoplasms, and the cardiovascular and genitourinary systems. A chapter on contrast materials outlines the mechanisms of paramagnetic contrast enhancement and highlights several promising contrast agents.

  13. Double resonator cantilever accelerometer

    DOEpatents

    Koehler, Dale R.

    1984-01-01

    A digital quartz accelerometer includes a pair of spaced double-ended tuning forks fastened at one end to a base and at the other end through a spacer mass. Transverse movement of the resonator members stresses one and compresses the other, providing a differential frequency output which is indicative of acceleration.

  14. Double resonator cantilever accelerometer

    DOEpatents

    Koehler, D.R.

    1982-09-23

    A digital quartz accelerometer includes a pair of spaced double-ended tuning forks fastened at one end to a base and at the other end through a spacer mass. Transverse movement of the resonator members stresses one and compresses the other, providing a differential frequency output which is indicative of acceleration.

  15. Single spin magnetic resonance

    NASA Astrophysics Data System (ADS)

    Wrachtrup, Jörg; Finkler, Amit

    2016-08-01

    Different approaches have improved the sensitivity of either electron or nuclear magnetic resonance to the single spin level. For optical detection it has essentially become routine to observe a single electron spin or nuclear spin. Typically, the systems in use are carefully designed to allow for single spin detection and manipulation, and of those systems, diamond spin defects rank very high, being so robust that they can be addressed, read out and coherently controlled even under ambient conditions and in a versatile set of nanostructures. This renders them as a new type of sensor, which has been shown to detect single electron and nuclear spins among other quantities like force, pressure and temperature. Adapting pulse sequences from classic NMR and EPR, and combined with high resolution optical microscopy, proximity to the target sample and nanoscale size, the diamond sensors have the potential to constitute a new class of magnetic resonance detectors with single spin sensitivity. As diamond sensors can be operated under ambient conditions, they offer potential application across a multitude of disciplines. Here we review the different existing techniques for magnetic resonance, with a focus on diamond defect spin sensors, showing their potential as versatile sensors for ultra-sensitive magnetic resonance with nanoscale spatial resolution.

  16. Magnetoelectric resonance engine

    SciTech Connect

    Moscrip, W.M.

    1992-09-15

    This patent describes a magnetoelectric resonance thermal machine. It comprises a reciprocating, multiple-piston, Alpha-type Stirling-cycle mechanical assembly; an electronic quadrature phase-lock circuit; an ancillary external energy and mass transfer subsystem; and a master microcomputer control system.

  17. Single spin magnetic resonance.

    PubMed

    Wrachtrup, Jörg; Finkler, Amit

    2016-08-01

    Different approaches have improved the sensitivity of either electron or nuclear magnetic resonance to the single spin level. For optical detection it has essentially become routine to observe a single electron spin or nuclear spin. Typically, the systems in use are carefully designed to allow for single spin detection and manipulation, and of those systems, diamond spin defects rank very high, being so robust that they can be addressed, read out and coherently controlled even under ambient conditions and in a versatile set of nanostructures. This renders them as a new type of sensor, which has been shown to detect single electron and nuclear spins among other quantities like force, pressure and temperature. Adapting pulse sequences from classic NMR and EPR, and combined with high resolution optical microscopy, proximity to the target sample and nanoscale size, the diamond sensors have the potential to constitute a new class of magnetic resonance detectors with single spin sensitivity. As diamond sensors can be operated under ambient conditions, they offer potential application across a multitude of disciplines. Here we review the different existing techniques for magnetic resonance, with a focus on diamond defect spin sensors, showing their potential as versatile sensors for ultra-sensitive magnetic resonance with nanoscale spatial resolution. PMID:27378060

  18. Resonance Ionization, Mass Spectrometry.

    ERIC Educational Resources Information Center

    Young, J. P.; And Others

    1989-01-01

    Discussed is an analytical technique that uses photons from lasers to resonantly excite an electron from some initial state of a gaseous atom through various excited states of the atom or molecule. Described are the apparatus, some analytical applications, and the precision and accuracy of the technique. Lists 26 references. (CW)

  19. RESONANT CAVITY EXCITATION SYSTEM

    DOEpatents

    Baker, W.R.

    1959-08-01

    A cavity excitation circuit is described for rapidly building up and maintaining high-level oscillations in a resonant cavity. The circuit overcomes oscillation buildup slowing effects such as ion locking in the cavity by providing for the selective application of an amplified accelerating drive signal to the main cavity exciting oscillator during oscillation buildup and a direct drive signal to the oscillator thereafter.

  20. Screening Resonances In Plasmas

    SciTech Connect

    Winkler, P.

    1998-12-01

    When it was suggested that a new recombination mechanism (Resonant Radiative Recombination (RRR)) which, based on very general physical arguments, should happen in dense plasmas and promises to provide useful information for the local temperature and density diagnostics of plasmas, they assumed the existence of screening resonances. For model potentials the existence of screening resonances has been demonstrated beyond reasonable doubt in a number of calculations. The key question, how well those potentials describe the dominant effects of a real plasma remains open. The relation of theoretical predictions to experimentally measurable effects is an important issue at the present stage of their research. In particular, RRR is expected to account for enhanced recombination rates of low energetic electrons with their ions, since the first stage is the resonant capture of a slow electron by an atom or ion. The mechanism that traps an electron is a combination of complicated many-body interactions of the ions and electrons. For clarity they start here, however, with a discussion in terms of local potential traps the shapes of which are determined predominantly and in an average way by two factors: the degree of screening present at the ionic site and the degree of short-range order in the immediate neighborhood of this ion.