Showing papers on "Resonance published in 1972"
459 citations
TL;DR: In this article, the rate of absorption of energy from a weak signal field by an atom driven by a strong pump field is evaluated, and the results are discussed in the context of a theorem which expresses the absorption line-shape function for general atomic systems in terms of a suitable atomic correlation function.
Abstract: The rate of absorption of energy from a weak signal field by an atom driven by a strong pump field is evaluated. The pump field and the signal field are assumed to induce transitions between the same pair of states, and their frequencies are both assumed to lie near the atomic resonance frequency for the transition in question. We find that the signal-field absorption line-shape function takes on negative values, representing stimulated emission rather than absorption, even though population inversion does not occur. This amplification of the signal field, which is most pronounced at high pump intensities, is shown to occur primarily at the expense of the pump field, which suffers an increased rate of attenuation. The results are discussed in the context of a theorem which expresses the absorption line-shape function for general atomic systems in terms of a suitable atomic correlation function.
448 citations
TL;DR: For a dilute aqueous solution of spin-labeled oxyhemoglobin, a τ2 of 26 ± 2 nsec was obtained in this paper, which increases linearly with viscosity as sucrose is added to the solution.
222 citations
TL;DR: In this paper, the authors interpreted the photoabsorption spectra of the lanthanides near the $4d$ absorption edge as transitions of the type $4{f}^{10}4{ f}^{N}\ensuremath{gf}$.
Abstract: The resonances in the photoabsorption spectra of the lanthanides near the $4d$ absorption edge are interpreted as transitions of the type $4{f}^{10}4{f}^{N}\ensuremath{\rightarrow}4{d}^{9}4{f}^{N+1}$. Calculations of the $4{d}^{9}4{f}^{N+1}$ energy levels and relative $\mathrm{gf}$ values for these transitions are shown to be in good agreement with the observed absorption spectra. The assumption that the lanthanides occur in trivalent form (with the exception of Eu and Yb) in the metallic solid state is confirmed by these results.
220 citations
IBM1
TL;DR: In this article, a simple application of the Stark-pulse technique, developed by Brewer and Shoemaker, demonstrates optical free induction decay-the optical analog of free-induction decay in NMR.
Abstract: A simple application of the Stark-pulse technique, developed by Brewer and Shoemaker, demonstrates optical free induction decay-the optical analog of free induction decay in NMR. A molecular sample which is coherently prepared by a cw laser beam exhibits such a decay when it is suddenly switched out of resonance by a Stark field. Observations are presented for a nondegenerate Doppler-broadened infrared transition of N${\mathrm{H}}_{2}$D, where the sample is optically thin, and the decay behavior can be compared quantitatively with a solution of the Bloch equations. When the molecular sample is prepared under steady-state conditions, the solutions are analytic; for pulse excitation, a numerical solution is required. The treatment invokes a hard-collision relaxation model. Such characteristics as the abrupt termination of the decay and the related edge echo, which result from Doppler dephasing, can be examined for Stark pulses of finite extent.
200 citations
TL;DR: In this paper, a strong resonance Raman effect of the I−3 ion when excited by the ultraviolet lines at 3638 and 3511 A of an argon ion laser, high intensity overtone progressions of the symmetric vibration νi were observed.
153 citations
TL;DR: In this paper, the authors review the experimental status of identifiable centrifugal-barrier effects in: (i) shapes of resonances, (ii) accounts for deviations in SU(2) and SU(3) predictions for ratios between partial decay widths, and (iii) accounting for the dependence on spin of the elastic widths of the resonances lying on the same Regge trajectory.
Abstract: (1) We review the experimental status of identifiable centrifugal-barrier effects in: (i) shapes of resonances, (ii) accounting for deviations in SU(2) and SU(3) predictions for ratios between partial decay widths, and (iii) accounting for the dependence on spin of the elastic widths of resonances lying on the same Regge trajectory. (2) We present a contour plot from which the "kinematic partial width" (centrifugal-barrier penetration factor times two-body phase space) of any resonance into any decay channel may be obtained immediately, given the orbital angular momentum, semiclassical impact parameter, and an assumed strong-interaction radius. Using this technique we display, as an example, the kinematically preferred decays of the high-spin mesons on the leading meson trajectory (assumed linear). (3) We obtain an approximate lower bound on the strong-interaction radius on the basis of general considerations. (4) We show that, for high-spin resonances, it can be expected that the mass enhancements in different decay channels associated with these resonances may be shifted by a half-width or so with respect to each other, because of different centrifugal-barrier effects in the different channels. (5) We also show that production cross sections of high-spin particles on leading linear trajectories by either formation or peripheral processes will be substantially suppressed by centrifugal-barrier effects. (6) Finally, we observe that the production cross sections and decay widths of mesons on the leading trajectory of the Veneziano model can be understood almost entirely on the basis of kinematical considerations if the radius of the region in which the decay particles interact strongly grows linearly with the mass of the decaying resonance.
150 citations
TL;DR: A high resolution proton nuclear magnetic resonance study of chymotrypsin A δ and Chymotsinogen A in water has shown a single resonance at very low magnetic fields, assigned to the hydrogen-bonded proton between His-57 and Asp-102.
140 citations
127 citations
TL;DR: For molecules with vibrational transition dipole moments, the energy transfer cross sections, σ vv, decrease rapidly with increasing vibrational energy discrepancy, ΔE as discussed by the authors, and their magnitudes at resonance are accurately fit by first order calculations using the transition-dipole interaction.
Abstract: Laser‐excited vibrational fluorescence measurements have given rates for nearly resonant vibrational energy exchange between the asymmetric stretch of CO2 and the stretching vibrations of 13CO2, N2O, CO, and 15N2 as a function of temperature and of 13CO and D2 at room temperature. For molecules with vibrational transition dipole moments the energy transfer cross sections, σ vv, decrease rapidly with increasing vibrational energy discrepancy, ΔE. Their magnitudes at resonance are accurately fit by first order calculations using the transition—dipole interaction, but that theory underestimates σ vv for Δ E ≥ 66 cm−1, especially at low temperatures. At resonance, σ vv is inversely proportional to temperature. As ΔE increases, σ vv decreases less rapidly with temperature (13CO2, Δ E = 66 cm−1), becomes temperature‐insensitive (N2O, Δ E = 125 cm−1), and finally increases with temperature (12CO, Δ E = 206 cm−1). It appears that rotation—translation coupling terms in the intermolecular potential operate simultan...
118 citations
TL;DR: Resonance Raman spectra have been recorded for cytochrome c in both reduced and oxidized forms, and the reduced form exhibits intense resonance scattering, and its spectrum is similar to that of oxyhemoglobin.
TL;DR: In this paper, the resonance Raman effect of the I − 1 3 ion was observed by the use of an ultraviolet nitrogen pulsed laser, and it was found that the totally symmetric stretching vibration of 112 cm −1 undergoes selective enhancement and the overtones up to the seventh order of this vibration could be observed.
TL;DR: In this article, high intensity overtone progressions of the totally symmetric vibration v 1 were observed, allowing estimates of the anharmonicity constants and harmonic frequencies to be made for the v 1 breathing mode.
Abstract: Resonance Raman spectra have been obtained from the MnO4 - and CrO4 2- ions in aqueous solutions and as solid. High intensity overtone progressions of the totally symmetric vibration v 1 were observed, allowing estimates of the anharmonicity constants and harmonic frequencies to be made for the v 1 breathing mode. Relative intensities have been measured in the resonance case and correlated with the absorption spectra. Also preresonance intensity data for CrO4 2- have been determined and discussed in terms of an existing theory. The overtone progression of v 1 shows a large increase in half-bandwidth with increasing vibrational quantum number.
TL;DR: In this paper, a standard [ π - HSP - t - π /2 - T ] n inversion recovery pulse sequence can be used to eliminate the residual HDO resonance from the spectrum.
TL;DR: In this article, the authors used a theta-pinch plasma at temperatures between 2 and 3*106 K and densities of 1 to 8*1016 cm-3 to make measurements on the satellite lines which appear on the long-wavelength side of the helium-like resonance lines of oxygen VII and nitrogen VI.
Abstract: Using a theta-pinch plasma at temperatures between 2 and 3*106 K and densities of 1 to 8*1016 cm-3, measurements have been made on the satellite lines which appear on the long-wavelength side of the helium-like resonance lines of oxygen VII and nitrogen VI. These satellites are due to emission from doubly excited or inner-shell excited lithium-like ions. The relative intensity of the satellites to the resonance lines were measured as a function of time. The intensities are shown to fit well to a quantitative theory which has been developed to account for the emission. This indicates that the dominant populating mechanism is by dielectronic recombination, which would be the only mechanism in a steady state plasma. However, the transient nature of the theta-pinch leads to an additional mechanism which contributes in the early phase of the plasma, i.e. the inner-shell excitation of lithium-like ions.
TL;DR: In this article, the angle variation of the 93Nb NMR linewidths is obtained for an off-stoichiometry lithium niobate crystal and the widths can be calculated on the basis of a model in which both the magnitude and direction of the electric field gradient are treated as random quantities.
Abstract: The angle variation of the 93Nb NMR linewidths is obtained for an off‐stoichiometry lithium niobate crystal. It is shown that the widths can be calculated on the basis of a model in which both the magnitude and direction of the electric field gradient are treated as random quantities. A second type of niobium, with a near zero quadrupole coupling constant, is shown to exist in off‐stoichiometric crystals. This amounts to roughly 6% of the total niobiums. This new resonance is undoubtedly associated with the mechanism of charge compensation and suggests that the excess niobium substitutes for lithium.
TL;DR: In this paper, the anisotropy, magnetostriction, and linewidth of germanium-substituted yttrium iron garnet single crystals of the composition {Y3−xMexII} [Fe2](Fe3−y−zMeyIVFezII) O12−δFδ(MeII=Ca2+,Pb2+,and MeIV=Ge4+,Si4+) have been studied by means of ferromagnetic resonance.
Abstract: The anisotropy, magnetostriction, and linewidth of germanium‐substituted yttrium iron garnet single crystals of the composition {Y3−xMexII} [Fe2](Fe3−y−zMeyIVFezII) O12−δFδ(MeII=Ca2+,Pb2+,and MeIV=Ge4+,Si4+) have been studied by means of ferromagnetic resonance. Analysis data of Fe2+, Ge4+, and of the impurities Pb2+, Ca2+, Si4+ and F− are given for all crystals as well as optical‐absorption coefficients in the wavelength range 1–2.5 μm. The resonance measurements have been carried out at 9.25 GHz in the temperature range 4.2–460 °K. A comparison of the temperature dependence of the anisotropy contributions caused by Fe2+ with the single‐ion model leads to a good agreement. However, it has to be assumend that only one‐third of the Fe2+ ions are effective. The contribution to the magnetostriction constants turns out to be positive for both λ100 and λ111. Maxima of the resonance linewidth were observed at about 40 and 370 °K.
TL;DR: In this article, the spin sublevel activity in phosphorescence, Frank-Condon maxima in emission, and molecular distortions are discussed, and the spin Hamiltonian parameters, including the zero-field splittings and Br and Cl excited state nuclear quadrupole coupling constants, are presented and interpreted.
Abstract: The optically detected magnetic resonance (ODMR) in zero field and the phosphorescence microwave double resonance (PMDR) spectra of 1,2,4,5‐tetrabromobenzene and 1,2,4,5‐tetrachlorobenzene have been obtained monitoring the low temperature (1.3°K) phosphorescence from both trap emission in neat single crystals and emission from a durene host. From the PMDR the major vibronic features of the spectra are assigned. The orbital symmetries in the excited triplet state, the principal and secondary contributions from the individual triplet spin sublevels to the electronic and vibronic origins in phosphorescence, the spin sublevel populations, and lifetimes are determined. In addition the spin Hamiltonian parameters, including the zero‐field splittings and Br and Cl excited state nuclear quadrupole coupling constants, are presented and interpreted. Finally, the relationship between spin sublevel activity in phosphorescence, Frank‐Condon maxima in emission, and molecular distortions are discussed.
TL;DR: In this paper, a hypersonic nozzle beam (Mach 19) of HCN molecules was studied by electric resonance spectroscopy, and an SF6 diluent was used to reduce the beam velocity by one-half and increase spectral resolution over a thermal (effusive) source.
Abstract: A hypersonic nozzle beam (Mach 19) of HCN molecules was studied by electric resonance spectroscopy. Translational temperatures of 4°K and rotational temperatures of 64± 30°K were found from a 283°K nozzle source. The monoenergetic character of the beam and the rotational cooling lead to an order of magnitude increase in signal‐to‐noise ratios. The absence of an appreciable velocity dispersion and a homogeneous radiation field allowed a critical comparison with theoretical two‐level resonance lineshapes. An SF6 diluent was used to reduce the beam velocity by one‐half and increase spectral resolution over a thermal (effusive) source. SF6 vibrational relaxation was observed. Chemically interesting species can be formed: ArXe, XeHCl, (HCl)2, (HCN)x, and (HF)x.
TL;DR: In this article, the dependence of resonance line width, resonance area, and magnitude of the Mossbauer effect on film thickness is analyzed for backscattering spectra obtained via the conversion electron, and an exponential attenuation law and Fermi-age/diffusion theory are used and intercompared.
TL;DR: The 14N nuclear quadrupole resonance spectra and spin-lattice relaxation times of the amino acids histidine, methionine, cystine, Cysteine and tyrosine as well as of the nucleic bases uracil, thymine, cytosine, and guanine have been determined by a 14N-proton double resonance technique in the laboratory frame as mentioned in this paper.
Abstract: The 14N nuclear quadrupole resonance spectra and spin‐lattice relaxation times of the amino acids histidine, methionine, cystine, cysteine, and tyrosine as well as of the nucleic bases uracil, thymine, cytosine, and guanine have been determined by a 14N‐proton double resonance technique in the laboratory frame. The experiments were performed on polycrystalline samples at 77°K or above this temperature. A theoretical estimate of the sensitivity of this method for a variety of experimental conditions is as well presented. It is shown that in contrast to usual double resonance techniques the method works even in the case of a short proton spin‐lattice relaxation time if only the nitrogen relaxation time is long.
TL;DR: In this article, it was shown that the rippling often observed on small progressive gravity waves can be explained in terms of a nearly resonant harmonic nonlinear interaction, where the phase speeds of the two waves must be nearly identical.
Abstract: We show that the rippling often observed on small progressive gravity waves can be explained in terms of a nearly resonant harmonic nonlinear interaction. The resonance condition is that the phase speeds of the two waves must be nearly identical. The in viscid analysis is generalized to any order in a small parameter proportional to the wave steepness. Wave tank measurements provide experimental evidence for most of the predicted results. The phenomenon of resonant rippling is further shown to be not just peculiar to capillary-gravity waves, but in fact possible for any weakly nonlinear dispersive wave system whose dispersion relation has discrete pairs of solutions nearly satisfying the resonance conditions.
TL;DR: The results from electron paramagnetic resonance studies are consistent with a pi-bounded structure for (Co)MbO(2), and the A(Co) and g values do not share the same principal axes.
Abstract: Single crystals of oxycobaltmyoglobin and deoxycobaltmyoglobin have been prepared and found to be isomorphous. The paramagnetic resonance spectra of deoxycobaltmyoglobin yield gxx = 2.330, gyy = 2.323, gzz = 2.028 with the z-axis parallel to the “heme” normal. The ACo and g tensors share the same principal axes with|ACo∥| = 79 G and|ACo[unk]| = 6 G. A value of AN = 17.5 G was also obtained for the e-N atom of the F8 histidine. There are two paramagnetic species in oxycobaltmyoglobin having apparently identical g-tensors (gξξ = 2.083, gηη = 2.006, and gζζ = 1.989) but different ACo-tensors. Furthermore, g values ACo do not share the same principal axes. The ACo-values for one of the species are (Axx = 16.7 G, Ayy = 5.95 G, Azz = 9.3 G), they are all 40% larger for the other species. The two species are oriented 90° to each other in the crystal. The results from electron paramagnetic resonance studies are consistent with a π-bounded structure for CoMbO2.
TL;DR: In this article, the positions of the high field hyperfine components in the paramagnetic resonance spectra of spin-labeled enzymes have been measured as a function of solvent viscosity and have been used to determine a rotational correlation time of 12 nanoseconds for α-chymotrypsin in water at 20° C.
TL;DR: In this paper, the authors compared the observed Raman spectra with calculated Q, S and O branches, using spectroscopic constants derived from the high resolution fluorescence measurements of Rank and Rao.