Showing papers on "Resonance published in 1988"
TL;DR: The first observation of stochastic resonance in an optical device, the bidirectional ring laser, is reported and the addition of injected noise can lead to an improved signal-to-noise ratio.
Abstract: We report the first observation of stochastic resonance in an optical device, the bidirectional ring laser. The experiment exploits a new technique to modulate periodically the asymmetry between the two counter-rotating lasing modes. The measurements verify that the addition of injected noise can lead to an improved signal-to-noise ratio (relative to that observed with no externally injected noise).
682 citations
TL;DR: Large resonant magnetization-sensitive x-ray scattering is predicted to occur in the vicinity of the L/ sub II/, L/sub III/, and M/sub II/--M/sub V/ absorption edges in the rare-earth and actinide elements, and at the K and L edges inThe transition elements.
Abstract: Large resonant magnetization-sensitive x-ray scattering is predicted to occur in the vicinity of the L/sub II/, L/sub III/, and M/sub II/--M/sub V/ absorption edges in the rare-earth and actinide elements, and at the K and L edges in the transition elements. These ''magnetic'' resonances result from electric multipole transitions, with the sensitivity to the magnetization arising from exchange. For some transitions, the magnetic scattering will be comparable to the charge scattering. The general features of the observed L/sub III/ resonance in Ho are discussed.
559 citations
TL;DR: A new optical chemical sensor was developed for chemical sensing based on light-excited surface plasmon measurement, which can be compact and simple, because of the absence of mechanical moving parts, by using multichannel angular light intensity detection with a photodiode array and a Fourier transform optical setup.
Abstract: A new optical chemical sensor was developed for chemical sensing based on light-excited surface plasmon measurement. Concentration of the chemical species is found in liquid or gas without the help of a reagent but by measuring the resonance condition of the surface plasmon on the sensing metal surface. The resonance condition is given by the dielectric constant of the sample faced on the metal. The developed sensor can be compact and simple, because of the absence of mechanical moving parts, by using multichannel angular light intensity detection with a photodiode array and a Fourier transform optical setup. Experimental results are shown for measurement of ethanol concentration in water. The detection limit for ethanol in water was 10(-4) wt./wt. by the experiments with the developed system.
338 citations
TL;DR: In this article, the authors used rotational cooling of molecules to ∼5 K by supersonic expansion and state-selective, multilevel saturation spectroscopy to obtain high-resolution spectra of the fundamental and first and second overtone transitions of C-H stretching modes in ground-electronic-state benzene and its dimer.
Abstract: We used rotational cooling of molecules to ∼5 K by supersonic expansion and state‐selective, multilevel saturation spectroscopy to obtain high‐resolution spectra of the fundamental and first and second overtone transitions of C–H stretching modes in ground‐electronic‐state benzene and its dimer. Greatly reduced linewidths (<3 cm−1 FWHM) in the rich spectra show that previously reported spectra have suffered from inhomogeneous congestion. Our observed spectral widths indicate that the vibrational lifetimes of the C–H stretches are at least a few ps, even at the energy of the second overtone (8800 cm−1). The ‘‘local mode’’ picture appears to apply when at least three quanta of C–H stretching motion are present. Spectra of the dimer are similar to those of the monomer but show a red shift of a few cm−1, the appearance of combination bands involving van der Waals vibrational modes, some intensity changes, and a broadening of spectral features that increases with the vibrational energy. The dimer’s predissociation lifetime at ∼3000 cm−1 vibrational energy exceeds ∼3 ps.
334 citations
TL;DR: In this article, an approach to suppress spurious resonances due to the probe in NMR is presented which utilizes DEPTH (I) pulse sequences to select homogeneous regions of the radiofrequency field.
313 citations
TL;DR: In this article, the behavior of plasma and fields in the transition layer supporting MHD surface waves is analyzed, assuming that the total pressure fluctuations, delta-P(tot), can be taken to be nearly constant across this thin transition layer, with a value nearly the same as would be obtained if the MHD wave were supported by a truly discontinuous surface.
Abstract: The behavior of plasma and fields in the transition layer supporting MHD surface waves is analyzed, assuming that the total pressure fluctuations, delta-P(tot), can be taken to be nearly constant across this thin transition layer, with a value nearly the same as would be obtained if the MHD wave were supported by a truly discontinuous surface Regarding therefore delta-P(tot) as known, the plasma and field equations in the transition layer were cast into a form in which delta-P(tot) appeared as a driving term Among the two resonances that appear (the cusp resonance and the Alfven resonance) special attention is given to the Alfven resonance, which affects the velocity and magnetic field components normal to the background magnetic field The effects of three types of viscosity on the Alfven resonance are considered, and it is shown that energy is pumped out of the surface wave into thin layers surrounding the resonant field lines
287 citations
TL;DR: A model using mathematical descriptions of the two currents derived in the preceding paper, with additional terms for leakage conductance and membrane capacitance, correctly predicts the oscillatory responses to applied current pulses, including the non‐linear dependences of oscillation frequency and quality factor on membrane potential.
Abstract: 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 description of the resonance mechanism. 6. To identify the factors most important in determining the hair cell's resonance properties, we systematically altered the values of selected parameters in the model. Frequency was most profoundly influenced by increasing the magnitude and activation rate of the Ca2+-activated K+ conductance, whereas the quality factor was most sensitive to increases in the level of the Ca2+ conductance. 7. By including a term describing activation of the hair cell's mechanically sensitive transduction conductance, we used the model to predict a tuning curve for responses to mechanical inputs of various frequencies.(ABSTRACT TRUNCATED AT 400 WORDS)
235 citations
TL;DR: In this paper, the relativistic MCSCF energies for a large number of excited states in the rare gases H, He, Ne, Ar, Kr and Xe have been studied in the gas phase at low pressure.
211 citations
TL;DR: In this article, the effects of FeCO distortion on the vibrational frequencies are attributed to back-bonding changes, as evidenced by the correlation of vF& with vCo. But this is not consistent with the available X-ray crystal structure data.
Abstract: The vibrational data on heme-CO complexes are analyzed with a view toward elucidating the structural evidence for distorted FeCO units in heme proteins. The effects of FeCO distortion on the vibrational frequencies are attributable to back-bonding changes, as evidenced by the correlation of vF& with vCo. Steric restraint of perpendicular binding increases Fe CO back-donation slightly. This is opposite to the direction expected if the FeCO unit is bent but is consistent with the expected effect of two other distortion coordinates, FeCO tilting and porphyrin buckling. Larger effects on back-bonding are attributable to polar interactions of distal residues with the bound CO, especially H bonding. Substantial FeCO bending is inconsistent with the relatively small frequency separation between vFeC and dFeCO observed in all adducts so far examined; this separation is calculated to increase strongly with the bending angle due to mixing of the modes. For a given displacement of the 0 atom from the heme normal, the energy required for the three distortion coordinates is calculated to increase in the order tilting < buckling < bending. The energy is minimized, as are the individual angular displacements, if all three contribute to the actual molecular distortion, and the small net change may result from the opposing effects of bending and of tilting and buckling in vFcc. This concerted model of FeCO distortion is not inconsistent with the available X-ray crystal structure data. It is inconsistent with EXAFS analysis of MbCO at 4 K, which has yielded a small value, 127 f 4O, for the FeCO angle from the attenuation of second-shell scattering relative to a protein-free model. This attenuation might be due instead to other changes in second-shell scattering, e.g. due to porphyrin buckling. functional role in lowering the C O affinit;, thereby raising ;he threshold for CO poisoning. Whether the CO affinity is actually (2) (a) Peng, S. M.; Ibers, J. A. J . Am. Chem. SOC. 1976, 98, 8032. (b) Scheidt. W. R.; Haller. K. J.: Fons. M.: Fashiko. T.: Reed. C. A. Biochemistrv (1) (a) Kuriyan, J.; Wiltz, S.; Karplus, M.; Petsko, G. J . Mol. Bid . 1986, 192, 133-154. (b) Hanson, J. C.; Schoenborn, B. P. J . Mol. Biol. 1981, 153, 117. (c) Baldwin, J. M.; Chothia, C. J . Mol. Biol. 1979, 129, 175. (d) Baldwin, J. M. J . Mol. Biol. 1980, 136, 103. (e) Steigeman, W.; Weber, E. J . Mol. B i d . 1979, 127, 309. (0 Tucker, P. W.; Philipps, S. E. V.; Perutz. M. F.; Houtchens, R. A.; Caughey, W. S. Proc. Natl. Aidd. Sci. U S . A . 1978, 75, 1076. (g) Heidner, E. J.; Ladner, R. C.; Perutz, M. F. J. Mol. Bid . 1976, 104, 707. (h) Norvell, J. C.; Nunes, A. C.; Schoenborn, B. P. Science (Washington, D.C.) 1975, 190, 568. ( i ) Padlan, E. A.; Love, W. E. J . Biol. Chem. 1974,249,4067. (j) Huber, R.; Epp, 0.; Formanek, H. J . Mol. Biol. 1970, 52, 349. 1981, 20, 3653. (c) Caron, C.; Mitschler, A,; Riviere, G.; Ricard, L:; Schappacher, M.; Weiss, R. J . Am. Chem. SOC. 1979, 101, 7401. (3) (a) Collman, J. P.; Brauman, J. I.; Halbert, T. R.; Suslick, K. S. Proc. Natl. Acad. Sci. U.S.A. 1976, 73, 3333. (b) Collman, J. P.; Brauman, J. I.; Everson, B. L.; Sessler, J. L.; Morris, R. M.; Gibson, Q. H. J. Am. Chem. SOC. 1983, 105, 3052. 0002-7863/88/1510-6024$01.50/0
181 citations
TL;DR: An optical sensor based on the phenomenon of light-excited surface plasmon resonance has been investigated to measure liquid chemical concentrations in this article, where a white light source is used to excite surface PLASmon waves at a metal/analyte interface.
Abstract: An optical sensor based on the phenomenon of light-excited surface plasmon resonance has been investigated to measure liquid chemical concentrations. A white light source is used to excite surface plasmon waves at a metal/analyte interface. The wavelength of maximum absorption in the reflected light depends uniquely on the refractive index of the analyte.
168 citations
TL;DR: In this paper, the third-order optical susceptibility of semiconductor microcrystallites is evaluated for different crystallite-size regimes ranging from weak quantum confinement, where only the center-of-mass motion of the electron-hole pairs is modified, all the way down to very small quantum dots, where the individual motion of electrons and holes is confined and the Coulomb attraction is unimportant.
Abstract: Optical nonlinearities in semiconductor microcrystallites are analyzed theoretically. The third-order optical susceptibility is evaluated for different crystallite-size regimes ranging from weak quantum confinement, where only the center-of-mass motion of the electron-hole pairs is modified, all the way down to very small quantum dots, where the individual motion of the electrons and holes is confined and the Coulomb attraction is unimportant. Large optical nonlinearities are computed for sufficiently narrow linewidths of the microcrystallites. It is predicted that the induced two-photon absorption resonance (biexciton resonance) shifts from below to above the exciton resonance when the crystallite radius is reduced from bulk to less than the exciton Bohr radius. The magnitude of the expected optical nonlinearities in the different confinement regimes is analyzed for various semiconductor materials.
TL;DR: In the case of electron spin resonance (ESR) in a 2DEG, however, the conditions are different as discussed by the authors, since strong exchange interaction can lead to a drastically different population of the spin levels even in GaAs-AlGaAs heterostructures, where the spin splitting of a Landau level is in the order of hundred µeV (at B ≈ 10T).
Abstract: The investigation of the magnetooptical excitations in a two-dimensional electron gas (2DEG) has up to now almost always been restricted to the frequency range between far infrared and visible light involving intersubband resonance, cyclotron resonance etc. [1,2]. However, the neighbouring range, covering millimeter and centimeter waves, has been neglected. This is not surprising, since the photon energies are smaller than the thermal energies even at liquid Helium temperatures. Accordingly, if there are two arbitrary energy levels a centimeter wave photon energy apart from each other, a resonant transition should hardly be observable, because these levels are equally thermally populated. In the case of electron spin resonance (ESR) in a 2DEG, however, the conditions are different. Strong exchange interaction (“g-factor-enhancement”) [3] can lead to a drastically different population of the spin levels even in GaAs-AlGaAs heterostructures, where the spin-splitting of a Landau level is in the order of hundred µeV (at B ≈ 10T). Hence, ESR can also be done in a 2DEG [4,5].
TL;DR: In this article, the sensitivity of the spectrum to the intensity of the radio frequency field and to the relative orientations of tensors is explored, and it is shown that applying a radio frequency of an intensity chosen to satisfy a rotary resonance condition can restore the heteronuclear splittings in the spectrum.
Abstract: In solid state magic angle spinning experiments on a polycrystalline sample containing dilute heteronuclear spin pairs, the usual spectrum is insensitive to small heteronuclear couplings between the spins, and to the relative orientations of the various interaction tensors. Applying a radio frequency of an intensity chosen to satisfy a rotary resonance condition can restore the heteronuclear splittings in the spectrum. Theory and numerical simulations of this effect are presented. The sensitivity of the spectra to the intensity of the radio frequency field and to the relative orientations of tensors is explored. To fully explain the experimental results, it is necessary to postulate a small phase modulation induced by the motion of the sample through a radio frequency field of non-uniform direction.
TL;DR: The possibility of ``quantum chaos'' in such driven molecular systems is discussed and the Morse oscillator is used to test the manifestations of classical resonance overlap suggested semiclassically.
Abstract: We compare the classical and quantum theories of a Morse oscillator driven by a sinusoidal field, focusing attention on multiple-photon excitation and dissociation. In both the classical and quantum theories the threshold field strength for dissociation may be estimated fairly accurately on the basis of classical resonance overlap, and the classical and quantum results for the threshold are in good agreement except near higher-order classical resonances and quantum multiphoton resonances. We discuss the possibility of ``quantum chaos'' in such driven molecular systems and use the Morse oscillator to test the manifestations of classical resonance overlap suggested semiclassically.
TL;DR: In this article, the authors report the observation of an instability when two counter-propagating pump beams interact with sodium atoms, which they describe as a coherent emission around the pump beams axis.
TL;DR: The results were shown to be consistent with previous results obtained on dry skulls, and no obvious correlation between lowest resonance frequency and skull size was found.
Abstract: Patients with skin penetrating titanium implants in the temporal bone, for attachment of bone‐anchored hearing aids, have made it possible to investigate the free‐damped natural frequencies (resonance frequencies) of the human skull in vivo. The resonance frequencies of the skull of six subjects were investigated. The resonance frequencies were extracted from two frequency response functions (acceleration/force) measured on each subject: One point measurement where the force and acceleration were both measured at the same point, and one transcranial measurement where the acceleration was measured contralaterally. Between 14 and 19 resonance frequencies were identified for each subject in the frequency range 500 Hz to 7.5 kHz. The two lowest resonance frequencies were found to be on the average 972 (range 828–1164) and 1230 (range 981–1417) Hz. The relative damping coefficients of all resonances were found to be between 2.6 and 8.9%. Due to the relatively high damping coefficients, it is assumed that the resonance frequencies do not significantly affect bone conducted sound. In the transcranial measurements, however, a few large antiresonances were found which may affect bone‐conducted sound. Intersubject variations were large, probably due to individual variations in skull geometry and in mechanical parameters. The results were shown to be consistent with previous results obtained on dry skulls. No obvious correlation between lowest resonance frequency and skull size was found.
TL;DR: Spin systems of 75 of the 98 amino acid residues in a protein, oxidized Anabaena 7120 ferredoxin (molecular weight 11,000), were identified by this approach, which represents a key step in an improved methodology for assigning protein nuclear magnetic resonance spectra.
Abstract: By applying a two-dimensional double-quantum carbon-13 nuclear magnetic resonance experiment to a protein uniformly enriched to 26 percent carbon-13, networks of directly bonded carbon atoms were identified by virtue of their one-bond spin-spin couplings and were classified by amino acid type according to their particular single- and double-quantum chemical shift patterns. Spin systems of 75 of the 98 amino acid residues in a protein, oxidized Anabaena 7120 ferredoxin (molecular weight 11,000), were identified by this approach, which represents a key step in an improved methodology for assigning protein nuclear magnetic resonance spectra. Missing spin systems corresponded primarily to residues located adjacent to the paramagnetic iron-sulfur cluster.
TL;DR: The sensitivity of the 27Al resonance position to the local environment can readily be distinguished allowing oxynitride structures, containing elements of similar scattering factor, to be refined as discussed by the authors.
Abstract: High-resolution solid-state 27Al NMR spectra have been obtained from ALON, β′-sialon and yttrium aluminate phases. The usefulness of 27Al magic-angle spinning NMR in phase characterization is shown by comparing different preparations of the yttrium aluminates. The sensitivity of the 27Al resonance position to the local environment means different units (e.g. AlN4, AlO4, AlO6) can readily be distinguished allowing oxynitride structures, containing elements of similar scattering factor, to be refined. This is exemplified for the β′-sialon phase. For quadrupolar nuclei (nuclear spin, I≥ 1) such as 27Al (I =), interaction with the local electric field gradient can cause extensive broadening of the resonance such that the NMR spectrum may not precisely quantify the aluminium distribution. © 1988, Wiley-Blackwell. All rights reserved.
TL;DR: In this article, a new and inexpensive X-band resonator structure for pulsed electron spin resonance and double resonance applications is introduced, which consists of a bridged loop structure and is distinguished by a good reproducibility and reliability.
Abstract: A new and inexpensive X‐band resonator structure for pulsed electron‐spin resonance and electron‐nuclear‐double‐resonance applications is introduced The resonator consists of a bridged loop structure and is distinguished by a good reproducibility and reliability It has a high filling factor and an adjustable Q value and is transparent to radio frequency fields with an upper limit >100 MHz The inner diameter of 5 mm allows convenient sample access of standard 4‐mm quartz tubes in the temperature range between 4 and 300 K Numerical computations of the resonant frequencies, the Q values, and the three‐dimensional distributions of the electromagnetic fields are presented They are based on a discretization method for the solution of Maxwell’s equations and include all dielectric elements of the resonator structure The field homogeneity in the sample area and the influence of the dimensions and the thickness of the metallic layers on field intensity, quality factor, and resonant frequency are determined e
TL;DR: The lack of vibronic structure in the absorption spectrum is shown to be caused by extensive progressions in low-frequency torsional modes and a large homogeneous linewidth together with thermal population of low- frequency modes and inhomogeneous site distribution effects.
TL;DR: In this paper, the pressure dependence of the HOMO-LUMO transition energy and the frequency of the longest wavelength longitudinal optical vibration of 45 A diameter CdSe clusters in methanol-ethanol solution have been measured up to 50 Kbar.
Abstract: The pressure dependence of the HOMO–LUMO transition energy and the frequency of the longest wavelength longitudinal optical vibration of 45 A diameter CdSe clusters in methanol–ethanol solution have been measured up to 50 Kbar. The LO mode shifts to higher frequency at a rate of 0.43 cm−1/Kbar, which corresponds to a Gruneisen parameter of 1.1. The HOMO–LUMO transition shifts to higher energy at 4.5 meV/Kbar, yielding a deformation potential of 2.3 eV. The pressure dependence of these properties closely resemble those of the corresponding bulk solid, confirming the point of view that the lattice properties of these clusters resemble those of the bulk, even though the optical properties are quite distinct.
TL;DR: In this article, a self-shielding superconducting solenoid system is designed to utilize flux conservation to cancel fluctuations in the ambient magnetic field in which they are located.
Abstract: Superconducting solenoid systems which produce large magnetic fields can be designed to utilize flux conservation to cancel fluctuations in the ambient magnetic field in which they are located. Such self‐shielding solenoids could be very useful for mass spectroscopy of trapped particles, nuclear magnetic resonance experiments, and magnetic resonance imaging.
TL;DR: The great success of the concept of a resonance in interpreting these experimental spectral features as obtained with the various spectro- scopies provides, in turn, strong support for the actual existence of a CO 2 derived resonance in these adsorption systems.
Abstract: The electronic spectra of CO chemisorbed on transition metals and copper as obtained with photoelectron spectroscopies, surface Penning spectroscopy, inverse photoemission spectroscopy, and x-ray absorption spectroscopy are discussed in regard to inherent features pointing to the existence of a CO 2${\ensuremath{\pi}}^{\mathrm{*}}$--derived resonance in these adsorption systems. Since the various spectroscopies probe the CO-metal systems predominantly in the excited final state, the spectra of one and the same line, however, are also affected by differences in the dynamic relaxation processes and nonequilibrium final-state charge configurations which are specific to each particular experimental method. In order to arrive at a unified interpretation of some seemingly controversial features in the electronic spectra of chemisorbed CO, we have invoked the notion of the CO 2${\ensuremath{\pi}}^{\mathrm{*}}$--derived resonance. Our model includes both initial-state chemical (i.e., backdonation-induced bonding) effects and final-state dynamical screening (relaxation) effects. Assuming a very small fractional occupation of the CO 2${\ensuremath{\pi}}^{\mathrm{*}}$ resonance in the case of weak chemisorption systems (e.g., CO/Cu), and notably larger occupation in the case of strong chemisorption (e.g., CO/Ni), it is possible to give a unified interpretation of the experimental features such as the threshold energies, level shifts, line shapes, etc., observed with CO adsorbed on transition metals and copper. The great success of the concept of a resonance in interpreting these experimental spectral features as obtained with the various spectro- scopies, provides, in turn, strong support for the actual existence of a CO 2${\ensuremath{\pi}}^{\mathrm{*}}$-- derived resonance in these adsorption systems.
TL;DR: In this paper, the similarities and differences for some emissions of importance in the atmospheres of Earth and Jupiter are examined for both a conservative resonance line and a line for which there is a considerable branching ratio are considered.
Abstract: Atomic resonance line emissions have been used to probe the structure and composition of the upper regions of planetary atmospheres. In this paper the similarities and differences for some emissions of importance in the atmospheres of Earth and Jupiter are examined. For each planet both a conservative resonance line and a line for which there is a considerable branching ratio are considered. On Earth examples of important conservative and nonconservative resonance emissions are OI 1304 A and OI 989 A, respectively. Both of these features are excited by photoelectron impact on atomic oxygen. The OI 1304-A triplet has an additional source due to resonant scattering of the solar OI 1304-A emission feature. These emissions are typically observed from a much different perspective than corresponding emissions from other planets, usually from inside the atmosphere, at substantial line-center optical depths. On Jupiter the brightest conservative resonance line is HI 1216A (Lyman α), while HI 1026 A (Lyman β) is an example of an important nonconservative resonance line. In this paper, models are presented for the intensities of these features as would be seen from a distance of several planetary radii, using the same geometry of observation for both Earth and Jupiter. The variations of the line-integrated emissions across the disk and near the limb of each planet are examined in detail. Line profiles for the emissions near the limb and at disk-center are also examined. The models reveal the importance of including inhomogeneities and temperature variations of the atmospheres in scattering models, and indicate that outer planet emissions previously interpreted as “electroglow” may be solely due to resonant scattering of solar emissions.
TL;DR: In this paper, the conditions of observation of a mirrorless four-wave mixing oscillation in atomic vapors are described, where a nonlinear medium interacts with two pump beams propagating in opposite directions.
TL;DR: The zero-field nuclear magnetic resonance (NMR) of Cu in the high-T c related oxide, La 2 CuO 4-δ, has been observed at 93.85±0.1 MHz for 63 Cu and 100.1± 0.78 kOe for 65 Cu with well-articulated quadrupole splittings at 1.3 K as discussed by the authors.
Abstract: The zero-field nuclear magnetic resonance (NMR) of Cu in the high- T c related oxide, La 2 CuO 4-δ , has been observed at 93.85±0.1 MHz for 63 Cu and 100.1±0.1 MHz for 65 Cu with well-articulated quadrupole splittings at 1.3 K. The resonance pattern is successfully analyzed as a result of the combined effect of a quadrupole coupling (coupling constant ν Q =31.9 MHz for 63 Cu and 29.5 MHz for 65 Cu with asymmetry parameter η=0.03) and a Zeeman term where the internal field ( H N =78.78 kOe) is nearly perpendicular to the direction of the maximum electric field gradient (EFG). The quadrupole split zero-field NMR signals have also been observed in CuO. The observed frequencies yield parameter values of 137.1±0.1 MHz, 146.9±0.1 MHz, 20.07 MHz, 18.57 MHz, 0.20, 121.5 kOe, and the direction of H N is found to be nearly parallel to the direction of the maximum EFG.
Patent•
07 Apr 1988
TL;DR: In this article, a method and an apparatus for detecting low concentrations of at least one (bio-)chemical component present in a test medium, having a metal layer as sub wall with an external glass prism, using the surface plasmon resonance effect.
Abstract: A method and an apparatus for detecting low concentrations of at least one (bio-)chemical component present in a test medium in a test cell, having a metal layer as sub wall with an external glass prism, using the surface plasmon resonance effect. A light ray is coupled in and, after attenuated total reflection, is coupled out and the intensity thereof is measured. The incidence angle position of the resonance curve is determined under the influence of the change, caused by the component, in the dielectric constant of the test medium near the metal layer. An adjustable selector is applied to the metal layer, in order to influence the incidence angle position of the resonance curve, through which the concentrations or concentration changes of one or more components in the test medium can be simultanously determined through one or more differential measurements. A preferential association and therefor a higher concentration at the metal layer of one component above another is brought about.
TL;DR: In this article, the diffusion coefficient D of Al in diopside, via a nuclear microanalysis technique: proton energy scanning using the 992 keV resonance of 27 Al(p, γ ) 28 Si.
TL;DR: In this paper, a CDW driven phase transition is seen and antiferromagnetic resonance (AFMR) is found below 10 K. The lack of any ESR signal in the conducting state is due to strong spin-orbit coupling (SOC) given by the nitrogen(p)-Cu(d) admixture.
TL;DR: NMR studies at 81.1 kG and 100 K on oriented single crystals are reported, and it is concluded that the 31.5-MHz NQR arises from the plane site.
Abstract: There are two types of Cu sites in YBa/sub 2/Cu/sub 3/O/sub 7/..sqrt../sub delta/, plane and chain. One gives a nuclear quadrupole resonance (NQR) at 22.0 MHz, the other at 31.5 MHz. Measurements of nuclear spin-lattice relaxation time in the superconducting state show that the 31.5-MHz site has a much larger energy gap (as though its T/sub c/ were 200 K), but different experimental workers have differed as to whether this is the chain or plane site. We report nuclear magnetic resonance (NMR) studies at 81.1 kG and 100 K on oriented single crystals, and conclude from symmetry arguments that the 31.5-MHz NQR arises from the plane site.