Showing papers on "Resonance published in 1971"
335 citations
TL;DR: In this article, a radio frequency-microwave double resonance spectrometer was proposed for the analysis of microwave spectra using a high-power amplitude-modulated radio-frequency field.
247 citations
171 citations
TL;DR: The mean life of the 3d 2 D doublet in SiII has been determined to be 047 ± 003 ns by a technique which utilizes arbitrarily normalized decay curves of all direct cascades in the analysis of the decay curve of the measured level, and thus exactly accounts for cascade effects as mentioned in this paper.
155 citations
139 citations
TL;DR: From thermodynamic measurements, it is possible to identify the ligand atoms bound to Fe3+ in nearly rhombic environments and D, the second rank axial coefficient in the spin Hamiltonian, is more than 4 times larger for primarily sulfur-ligated than for primarily oxygen-ligate high spin ferric iron.
131 citations
TL;DR: In this article, a numerical solution of the close-coupled quantal equations, including closed channels, for the collinear H + H2 reactive collision is presented, where the resonances are due to strong coupling terms, corresponding to vibrational nonadiabaticity.
127 citations
Journal Article•
TL;DR: In this paper, the authors derived the activity composition relation in orthopyroxene from the "partial" activities of Mg2+ and FeH at the two sites at 500, 600, 700, and 800°C.
Abstract: The distribution of Mg2+ and Fe"+ between the Ml and M2 sites in orthopyroxene (Fe, Mg).Sh06 at 500, 600, 700, and 800 °C, determined by Mossbauer resonance spectro scopy, can be interpreted in terms of Guggenheim's (19 67) "simple mixture" model for the individual sites. The standard free energy change !:J.G0 for the F e"-Mg2 exchange between the two sites and the adjustable energy constants W for the Fe"+-Mg2+ mixing on the Ml and M2 sites vary linearly with the inverse of the absolute temperature between 600 and 800°C. Fe"+-MgH mixing at the Ml site is more non-ideal than that at the M2 site, both approach ing ideality with increasing temperature. "Partial" excess thermodynamic functions of mix ing of Mg2+-Fe"+ on the individual sites are calculated using the "simple mixture" model. The activity-composi tion relation in orthopyroxene is derived from the "partial" activ ities of Mg2+ and FeH at the two sites at 500, 600, 700, and 800°C. The excess free energy of mixing of the Fe and Mg components in orthopyroxene at various temperatures is ex pressed as a polynomial in the mole fraction, using Guggenheim's equation with three con stants A o, A1, and A2, all of which decrease systematically as the temperature increases from 600 to 800°C .
127 citations
123 citations
TL;DR: Deuteron magnetic resonance (DMR) is used to study the mobility of the hydrocarbon chains, in isotopically enriched molecules to further characterise the motions of particular groups in membranes.
116 citations
TL;DR: In this paper, a simple sample technique which makes it possible to record Raman spectra of highly absorbing solids is described, where the main feature is a rotating sample system containing pressed crystal powders, on which the laser beam is focused.
Abstract: A simple sample technique which makes it possible to record Raman spectra of highly absorbing solids is described. The main feature is a rotating sample system containing pressed crystal powders, on which the laser beam is focused. The relative motion between laser focus and sample surface avoids heating and decomposition of the crystal powder. With this technique it is, for instance, possible to obtain a Raman spectrum of solid potassium permanganate, displaying a progression of strongly resonance enhanced overtones of the totally symmetric permanganate mode as well as a well-defined weakly enhanced spectrum for the other internal modes.
TL;DR: The iron electron-nuclear double resonance (ENDOR) spectra of reduced iron-sulfur proteins (two-iron ferredoxins) from spinach, parsley, pig adrenal cortex and Pseudomonas putida unequivocally show two inequivalent iron atoms at the active sites of each of these proteins.
TL;DR: In this paper, a model for the kinetics of the cooled direct-discharge-excited carbon monoxide laser is presented, which includes the following processes: (a) Vibration-to-vibration (V•V) energy exchange among the anharmonic vibrational states occurring in CO−CO collisions.
Abstract: A model for the kinetics of the cooled direct‐discharge‐excited carbon monoxide laser is presented. The kinetic mechanism responsible for creating the observed population inversions cannot be explained by simple one‐step resonance transfer between an excited metastable and the CO molecule, in view of the many vibrational bands which lase in this system. The present paper analyzes a kinetic model of the CO laser which includes the following processes: (a) Vibration‐to‐vibration (V‐V) energy exchange among the anharmonic vibrational states occurring in CO–CO collisions. (b) Resonance electron impact excitation of the lower CO vibrational states. (c) Radiative decay of the CO vibrational states. (d) Collisional quenching of vibrational excitation in CO–He collisions. Using a Morse anharmonic oscillator model of the CO vibrational states, kinetic equations are formulated which govern the individual vibrational state populations, subject to the preceding processes. The resulting set of nonlinear algebraic equations is solved by an interative technique for the steady‐state vibrational populations. Small‐signal laser gain is also predicted as a function of the following discharge conditions: (1) electron temperature, (2) electron concentration, (3) heavy species translational temperature, (4) CO partial pressure, and (5) He partial pressure. Comparison is made with recent experimentally obtained small‐signal gain data for the CO laser, as well as with other experimental results for CO lasers. It is shown that experimental results are consistent with an inversion created by electron impact excitation of the lower CO vibrational levels, followed by rapid redistribution of energy among the higher CO vibrational states via off‐resonant vibration‐vibration energy exchange. The present kinetic model successfully interprets the variation of gain with vibrational state, the observed strong temperature dependence of the gain, and the influence of He diluent in the discharge. The possibilities for using this pumping mechanism to obtain cw lasing with other diatomic species and in various laser configurations are also discussed.
TL;DR: In this article, a single acoustic resonance, excited by vortex shedding from the trailing edge of a flat plate, has been studied in detail, where the mode was traversed at resonance and the modal shape and natural frequency were found to agree well with computations.
TL;DR: In this article, electron spin resonance and nuclear magnetic resonance were used to study paramagnetic vanadium vanadium-phosphate and molybdenum phosphate glasses.
Abstract: Paramagnetic vanadium‐phosphate and molybdenum‐phosphate glasses have been studied using electron‐spin resonance and nuclear magnetic resonance. These glasses were nominally 80% MO:20% P2O5, where MO denotes the transition‐metal oxide. The electron‐spin‐resonance results showed a strongly exchanged, narrowed interaction with V4+/V5+ and Mo5+/Mo6+ ratios and line shapes which were independent of temperature over the range 77°–300°K. Since the conductivity is nonlinear in this temperature range, the result is direct evidence that the mobility is temperature dependent and that the average paramagnetic‐site is unchanged over this temperature range. The nuclear magnetic resonance of 51V and 31P in the glasses verifies the assumption of exchange narrowing. The 51V quadrupole coupling (1.5 MHz) and spin‐lattice relaxation time (T1<500 μsec) were temperature independent over the 77°–300°K range. The 31P resonances in each of the glasses also had temperature‐independent properties. For the molybdenum glass the lin...
TL;DR: In this article, a contactless plate wave excited in thin sheets (such as paper or cardboard) directly from air without touching the sample is described, which may prove to be useful in online testing of various other, non-woven materials like plastic sheets.
TL;DR: In this article, the simple optical theory of aggregated metal systems, due to Maxwell-Garnett, is analyzed and the complex dielectric constant of the system, and that of the constituent metal aggregates, are represented as transformations.
Abstract: In this part, the simplest optical theory of aggregated metal systems, due to Maxwell-Garnett, is analyzed. The complex dielectric constant of the system, and that of the constituent metal aggregates, are represented as transformations. The functions show single and double poles in certain regions of physical interest, indicating resonance behavior. These features are explored for free-electron metals, and an optical "conduction resonance" for the aggregated system is discovered. The resonance frequency and the magnitude of the optical conductivity are calculated, along with the plasma frequency and the magnitude of the bulk electron loss function. A relation between conduction and plasma resonances is established and it is found to be independent of the free-electron parameters of the metal. This, and other results, indicate that the conduction resonance is a macroscopic effect, being due to a collective polarization interaction between the constituent metal aggregates, and it may be looked upon as a kind of transverse plasma resonance. In the second part, the present results will be applied to real metals.
TL;DR: In this article, the E1 giant resonance was identified as the E 1 giant resonance at 9, 12 and 15 MeV, respectively, and the resonance at 12 and 12 MeV was assigned to M1 and M2, respectively.
TL;DR: In this article, the radiative lifetimes and absolute oscillator strengths were analyzed for Ca, Mg, B and Al prominent resonance transitions, and the relative oscillator strength was estimated.
Abstract: Ca, Mg, B and Al prominent resonance transitions radiative lifetimes and absolute oscillator strengths
TL;DR: In this paper, the 13C nuclear spin-lattice relaxation time T1 was studied in liquid CS2 from −106°C to +35°C at resonance frequencies of 14, 30, and 62 MHz.
TL;DR: In this paper, the authors focus on the applications of 119mSn Mӧssbauer spectroscopy to the study of organotin compounds and show that in any resonance experiment the resonance condition is best observed by systematically perturbing the system and then noting the influence of the variation on the measurable parameters.
Abstract: Publisher Summary This chapter focuses on the applications of 119mSn Mӧssbauer spectroscopy to the study of organotin compounds. The phenomenon of resonance depends on having a pair of systems, the emitter of energy and the absorber, with nearly the same characteristic frequencies. The emission of radiation arises from transitions between discrete electronic energy levels with both the emitting and the absorbing sodium atoms having the same level separation. The energies involved in the nuclear transitions are much larger than those in atoms, but the natural widths of the spectral lines are about the same. In any resonance experiment the resonance condition is best observed by systematically perturbing the system and then noting the influence of the variation on the measurable parameters. In chemical applications of the Mossbauer effect the source and absorber nuclei are usually in different chemical states.
TL;DR: In this article, the inversion problem is used to construct the intermolecular potential of a given set of scattering data for a single-collision set of atoms and molecules.
Abstract: Chemistry of the gas phase is essentially a study of what happens when atoms and molecules collide with one another. If the gas is not too dense, then one only needs to consider the collision of an individual atom or molecule with another individual atom or molecule. From a detailed understanding of this relatively simple binary encounter one can, in principle (and to some extent in practice), deduce the macroscopic kinetic properties of the gas, such as rate constants for chemical reaction, relaxation times for decay of molecular excitation (electronic, vibrational, or rotational), and transport coefficients. From another point of view, the accurate measurement of atomic and molecular scattering properties under single-collision conditions can lead to rather direct, quantitative information about the intermolecular forces between the collision partners. For the simplest collision system, the elastic scattering of two atoms, this “inversion problem” (the construction of that unique intermolecular potential which produces a given set of scattering data) is essentially s o l ~ e d , ~ ~ and Buck and Pauly5 have recently carried out the procedure in constructing the Na-Hg interatomic potential directly from molecular beam scattering data. For a more complicated collision system the inversion problem has not yet been rigorously solved, but it is nevertheless possible to obtain some quantitative information about the intermolecular potential. Study of the dynamics of elemental atomic and molecular collisions, therefore, has two-pronged implications: one can use the collision results, obtained experimentally or theoretically, to deduce (via the machinery of statistical mechanics) macroscopic observables, or one can start with experimentally obtained scattering data and work backward to construct the intermolecular potential giving rise to the observed scattering. Figure 1 illustrates the relation between
TL;DR: Using paramagnetic resonance, it was shown that a photochromic center in SrTiO3 is Fe5+ (3d3), its resonance parameters are g = 2.0131 ± 0.0008, A( 57 Fe) = (8.6 ± 0.1) x 10 −4 cm −1, as a function of valency the positive g-shift of Fe5+, lies nearly on a straight line joining those of the isoelectronic Cr3+ and Mn4+.
TL;DR: In this article, the rotational transitions of several symmetric top molecules have been measured in the 120-250 GHz range and the new molecule constants obtained are: HJKK = 5.8 Hz for CH379Br and HJKN = 4.3 Hz for H3127I.
TL;DR: In this paper, the stochastic Liouville method is applied to analyze the general problem of unsaturated ESR line shapes for triplets undergoing rotational diffusion, and detailed line shape simulations are obtained for the cases of high, low, and zero-field resonance, large or small values of an axially symmetric zero field splitting, and slow through fast ESR diffusion.
Abstract: The stochastic Liouville method is applied to analyze the general problem of unsaturated ESR line shapes for triplets undergoing rotational diffusion. Detailed line shape simulations are obtained for the cases of high‐, low‐, and zero‐field resonance, large or small values of an axially symmetric zero‐field splitting, and slow through fast rotational diffusion. It is shown how all these parameters can have profound effects on the observed ESR spectra.
TL;DR: In this paper, the authors measured the profile of the calcium 4226·73 A resonance line using a standard neon-filled hollow-cathode lamp using a variable gap Fabry-Perot interferometer.
TL;DR: The use of a linear resonator instead of a microwave resonant cavity increases the sensitivity of any resonance spectrometer when studying electron resonance in metals as discussed by the authors, and this technique is used to study the temperature dependence of the line shape of the conduction-electron spin resonance in a lithium film for thicknesses ranging from 0.3 to 30 skin depths.
Abstract: The use of a linear resonator instead of a microwave resonant cavity increases the sensitivity of any resonance spectrometer when studying electron resonance in metals. This technique is used to study the temperature dependence of the line shape of the conduction-electron spin resonance in a lithium film for thicknesses ranging from 0.3 to 30 skin depths. Dyson's theory is found to apply at high temperatures. Deviations below 120 \ifmmode^\circ\else\textdegree\fi{}K due to the anomalous skin effect provide a method of determining the microwave surface impedance in the alkali metals.
TL;DR: In this article, the response to random excitation of a thin rectangular plate inserted in an infinite baffle is considered, and an approximate solution of the resulting infinite set of linear simultaneous equations for the plate modal velocity amplitudes is obtained in terms of modal admittances of the plate-fluid system.