Showing papers on "Resonance published in 1974"
TL;DR: In this article, a double-barrier structure with a thin GaAs sandwiched between two GaAlas barriers has been shown to have resonance in the tunneling current at voltages near the quasistationary states of the potential well.
Abstract: Resonant tunneling of electrons has been observed in double‐barrier structures having a thin GaAs sandwiched between two GaAlas barriers. The resonance manifests itself as peaks or humps in the tunneling current at voltages near the quasistationary states of the potential well. The structures have been fabricated by molecular beam epitaxy which produces extremely smooth films and interfaces.
1,633 citations
525 citations
TL;DR: In this paper, a collisionless toroidal plasmas with smooth nonuniformities is considered and a heating scheme based on the spatial resonance of shear Alfven waves is proposed.
Abstract: Heating of a collisionless plasma by utilizing the spatial resonance of shear Alfven waves is proposed and application to toroidal plasmas is discussed. The resonance exists due to the nonuniform Alfven speed. This heating scheme is analyzed in one dimension including the effects of a shear magnetic field and plasma compressibility. For plasmas with smooth nonuniformities (| k⊥l | ≫ 1, k⊥ is the wavenumber prependicular to the ambient magnetic field and the nonuniformity direction, and l is the scale length of the nonuniformity), the energy absorbed per unit surface area per driving cycle is [b02(μ0k⊥)−1]. Here, b0 is the flux density of the driving magnetic field evaluated at the resonant point. With sharp nonuniformities (| k⊥l | ≪ 1), absorption is large if the surface eigenmode is excited. The corresponding value is [b02(μ0k⊥)−1(k⊥l)−1]. Otherwise, it is [b02(μ0k⊥)−1(k⊥l)].
365 citations
TL;DR: In this paper, a simple method is described to calculate the capacitances of rectangular and circular microstrip disk capacitors, and the influence of the fringing field on the resonance frequencies of microstrip disks resonators is calculated.
Abstract: A simple method is described to calculate the capacitances of rectangular and circular microstrip disk capacitors. From the edge capacitances of the capacitors the influence of the fringing field on the resonance frequencies of microstrip disk resonators is calculated. A theory to compute the resonance frequencies of microstrip resonators with high accuracy is presented. The resonance frequencies are calculated from a resonator model employing an effective width and length or radius, respectively, filled with a medium of a "dynamic dielectric constant." Theoretical and experimental results are compared and found to be in agreement within 1 percent.
296 citations
TL;DR: In this paper, the spectrum of resonantly scattered light at right angles to a sodium atomic beam was reported, with the Stark effect sidebands recorded as a function of both the laser intensity and its detuning from resonance.
Abstract: The spectrum of resonantly scattered light at right angles to a sodium atomic beam is reported. The light source was a cw dye laser tuned to resonance with a hyperfine component of the Dz line, and incident at right angles to the atomic beam. The spectrum, with the Stark effect sidebands, was recorded as a function of both the laser intensity and its detuning from resonance. The overall resolution is better than 20 MHz.
254 citations
Journal Article•
221 citations
208 citations
TL;DR: In this paper, the authors measured the charge transfer rate constants for reactions of He+, Ne+, Ar+, Kr+, and Xe+ with N2, O2, CO, NO, CO2, N2O, and CH4 using an ion cyclotron resonance spectrometer.
Abstract: Charge transfer rate constants for reactions of He+, Ne+, Ar+, Kr+, and Xe+ with N2, O2, CO, NO, CO2, N2O, and CH4 were measured using an ion cyclotron resonance spectrometer. The absolute values of the rate constants were within the upper limit predicted from the Gioumousis‐Stevenson orbiting theory for ion‐molecule reactions. The magnitudes for the charge transfer rate constants are discussed with respect to (1) the availability of an energy level of the molecular ion resonant with the recombination energy of the rare gas ion, and (2) the value of the Franck‐Condon factor connecting this energy level of the molecular ion with the molecular neutral.
201 citations
TL;DR: In this article, the ΔJ = 0,l-doublet transitions of OCS isotopes (16O12C32S, 16O 12C33S and 16O12c34S) in the (0110) vibrational state have been measured in a molecular-beam electric-resonance spectrometer equipped with a nozzle source.
190 citations
TL;DR: In this paper, the resonance Raman spectra of β-carotene in isopentane solution have been obtained at low temperature, using eight output lines of the argon-ion laser and a line of the heliumcadmium laser.
183 citations
TL;DR: In this article, a general theory of the spin dynamics of anisotropic Fermi superfluids of the generalized BCS type was developed, under conditions which should be realistic for any such phase of liquid 3 He occurring below 3 mK.
TL;DR: It is concluded that the charge relay system from Asp102 across His57 to Ser195 is intact in chymotrypsin Aδ and chymotsinogen A, and that, in the native enzyme, it slightly polarizes Ser195.
TL;DR: In this article, the effect of molecular motion on NMR powder spectra governed by axially symmetric shielding tensors is investigated, and the results show that at low temperatures the powder pattern for a rigid solid is observed, from which we obtain the shielding anisotrophy Δσ = σ − σ⊥ = −405 ± 10 ppm.
TL;DR: In this paper, nuclear triple resonance (TRIPLE) experiments on free radicals in solution not only give considerable signal-to-noise improvement as compared to ENDOR, but also decrease the observed linewidth and give additional information about the number of protons contributing to a particular hfs constant.
Abstract: Electron nuclear triple resonance (TRIPLE) experiments on free radicals in solution not only give considerable signal‐to‐noise improvement as compared to ENDOR, but also decrease the observed linewidth and give additional information about the number of protons contributing to a particular hfs constant. The experimental setup is described and the results are discussed in terms of a phenomenological theory.
TL;DR: In this article, a study was made of the efficiency of E-V transfer from O(1 D) to CO using a molecular resonance fluorescence technique, which utilizes optical pumping from the v = 1 level of the ground state of CO by A 1 Pi-X 1 Sigma radiation.
Abstract: With the aid of a molecular resonance fluorescence technique, which utilizes optical pumping from the v = 1 level of the ground state of CO by A 1 Pi-X 1 Sigma radiation, a study is made of the efficiency of E-V transfer from O(1 D) to CO. O(1 D) is generated at a known rate by O2 photodissociation at 1470 A in an intermittent mode, and the small modulation of the fluorescent signal associated with CO (v = 1) above the normal thermal background is interpreted in terms of E-V transfer efficiency. The CO (v = 1) lifetime in this system is determined mainly by resonance trapping of the IR fundamental band, and is found to be up to ten times longer than the natural radiative lifetime. For CO, (40 plus or minus 8)% of the O(1 D) energy is converted into vibrational energy. By observing the effect of N2 on the CO (v = 1) fluorescent intensity and lifetime, it is possible to obtain the E-V transfer efficiency for the system O(1 D)-N2 relative to that for O(1 D)-CO. The results indicate that the efficiency for N2 is (83 plus or minus 10)% of that for CO.
TL;DR: A comparison of hyperfine coupling constants obtained by electron-nuclear double resonance spectroscopy of in vitro monomer chlorophyll and bacteriochlorophyll free radicals with those of the photoesr signal associated with light conversion in photosynthesis provides convincing support for the special pair model for the in vivo photo-reaction center.
Abstract: A comparison of hyperfine coupling constants obtained by electron-nuclear double resonance spectroscopy of in vitro monomer chlorophyll and bacteriochlorophyll free radicals with those of the photoesr (electron spin resonance) signal associated with light conversion in photosynthesis provides convincing support for the special pair model for the in vivo photo-reaction center.
TL;DR: The authors' results establish that the bound oxygen is in the form of peroxide (O22−), and suggest that the 282 cm−1 peak corresponds to a vibration involving the magnetically-coupled Cu(II)··Cu( II) centers.
TL;DR: A numerical solution of a system of diffusion-coupled Bloch equations, including the modulation field, yields nitroxide spin label paramegnetic resonance spectra that are sensitive to rotational correlation times (τ 2 ) in the range 10 −7 sec ⩽ τ 2⩽ 10 −3 sec as discussed by the authors.
TL;DR: In this article, the authors used magnetic resonance and double resonance techniques to detect triplet states of chlorophyll and chlorophylla in n-octane solutions at 2°K.
Abstract: The zero‐field EPR transitions for the triplet states of chlorophyll a and chlorophyll b in n‐octane solutions at 2°K have been observed by optical detection methods. Both triplet absorption detection of magnetic resonance and fluorescence‐microwave double resonance techniques were used. Sharp‐line (5–20 MHz) zero‐field EPR spectra were recorded for both molecules. The rates of depopulation for the individual triplet state spin sublevels were determined by microwave‐modulated fluorescence intensity measurements. These experiments show that the middle spin sublevel is the most active in triplet state intersystem crossing for both chlorophyll a and chlorophyll b.
TL;DR: In this paper, a broad-band laser showed more effective heating of the plasmas than a narrowband laser and the decrease of the reflectivity appeared when the laser intensity increased up to 1 order of magnitude larger than the threshold of parametric instability.
Abstract: Brillouin backscattering from laser-produced plasmas of hydrogen and deuterium has shown an isotope effect in the red-side region of the generated second-harmonic light. This isotope shift is explained by the parametric instability at the cutoff region using the phase-matching condition of the waves. The decrease of the reflectivity appeared when the laser intensity increased up to 1 order of magnitude larger than the threshold of the parametric instability. A broad-band laser showed more effective heating of the plasma than a narrow-band laser.
TL;DR: In this article, a theory for the time dependence of scattering off an atomic or molecular resonance using tunable dye laser pulses is presented, and the main conclusion is that there is no exponentially decaying component which depends upon the frequency difference between the exciting pulse and the resonance.
TL;DR: In this paper, the resonance Raman spectra of copper porphin in solution were obtained using the tunable rhodamine 6G dye, Ar+, and HeCd lasers for excitation.
Abstract: Resonance Raman spectra of copper‐porphin in solution have been obtained using the tunable rhodamine 6G dye, Ar+, and HeCd lasers for excitation. Several bands show variation of intensity with excitation wavelength and many combination and overtone bands have been observed with 5145 A excitation. Depolarization ratios for the two anomalously polarized bands [ρl > (3/4)] at 1322 and 1587 cm−1 remain constant (∼45) with all the exciting wavelengths in the α and β absorption regions while some polarized bands show variation of their ρl values. It is shown that the rigorous molecular symmetry of Cu‐porphin in solution is D4h. Symmetry species of the vibrational modes have been assigned.
TL;DR: Laser-excited resonance Raman spectra of molecular vibrations in the gaseous, liquid, and solid state are reviewed in this paper, where a short summary of the recently developed Raman techniques for absorbing materials is also given.
Abstract: Laser-excited resonance Raman spectra of molecular vibrations in the gaseous, liquid, and solid state are reviewed. A short summary of the recently developed Raman techniques for absorbing materials is also given. A bibliography is added in an appendix which covers the literature of laser-excited resonance Raman spectra of molecular vibrations of more complicated molecules, mostly of biological interest.