Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Resonator defined

In the classical limit h - 0, the spectrum of the Landau-von Neumann superoperator tends to the spectrum of the classical Liouvillian operator. If the classical system is mixing, the classical Liouvillian spectrum is always continuous so that we may envisage an analytic continuation to define a discrete spectrum of classical resonances. It has been shown that such classical resonances are given by the zeros of the classical zeta function (2.44) and are called the Pollicott-Ruelle resonances sn(E) [63], These classical Liouvillian resonances characterize exponential decay and relaxation processes in the statistical description of classical systems. The leading Pollicott-Ruelle resonance defines the so-called escape rate of the system,... [Pg.514]

According to the definitions given in Poschel (Poschel 1993), the resonant domain associated to a lattice A is a neighborhood of the resonance defined in the following way first we require that the action is suitably close to the resonance through the inequality ... [Pg.189]

The term Muon Spin Resonance defines a NMR-type technique. In the presence of a static external field one induces muon spin flips by the application of resonant radio frequency (Kitaoka et al. 1982, Kreitzman 1990, Hampele et al. 1990, Nishiyama 1992, Scheuermann et al. 1997, Cottrell et al. 1997) or microwave field (Kreitzman et al. 1994). The resonance condition is detected via a loss of muon polarization. As in NMR, firequency shifts and linewidth are the sensitive parameters. [Pg.62]

Air-packaged microresonators are widely used in a variety of low-frequency applications such as accelerometers, gyroscopes, and sensors. In many of these applications, the quality factor of the resonator, defined as the ratio of total energy to energy dissipated per cycle, is a key performance variable but is very difficult to predict. The problem is that the dominant loss mechanism for many air-packaged resonators is viscous drag, and to predict drag, it is necessary to accurately determine the detailed airflow in these typically very complicated three-dimensional resonators. [Pg.186]

Here Cg-(S) is the function representing the time properties of the molecular resonances, defined as the transform... [Pg.298]

Note that of the three independent orientations of a dipole two are parallel to the surface and one is perpendicular to the surface. Hence, on average, B = 2B///2 + B /3 = 1. Nevertheless, it is possible for x nnd Bn to be individually large in magnitude, provided they are of opposite sign. This will occur near the dipolar plasmon resonance, defined by the condition Re[s(0)) + 2 Ss] 0. The magnitudes will be particularly large when Im[e(eo) + 2 sj is small. [Pg.203]

The other cantilever property is the quality factor, Q, a measure of cantilever damping. This is inversely proportional to the damping factor. It is also the ratio of the resonance frequency cOo to the full frequency width at half maximum of the resonance, defined in terms of energy. [Pg.98]

Thus, laser oscillation occurs inside a resonator confining the laser light. The resonator defines the frequency distribution and the spatial distribution of the output light. A resonator with planar mirrors separated by distance L supports longitudinal modes with discrete frequencies... [Pg.1166]

In an electron spin resonance spectrometer, transitions between the two states are brought about by the application of the quantum of energy hv which is equal to g H. The resonance condition is defined when hv = g H and this is achieved experimentally by varying H keeping the frequency (v) constant. Esr spectroscopy is used extensively in chemistry in the identification and elucidation of structures of radicals. [Pg.152]

The surface work fiincdon is fonnally defined as the minimum energy needed m order to remove an electron from a solid. It is often described as being the difference in energy between the Fenni level and the vacuum level of a solid. The work ftmction is a sensitive measure of the surface electronic structure, and can be measured in a number of ways, as described in section B 1.26.4. Many processes, such as catalytic surface reactions or resonant charge transfer between ions and surfaces, are critically dependent on the work ftmction. [Pg.300]

The ability to assign a group of resonance states, as required for mode-specific decomposition, implies that the complete Hamiltonian for these states is well approxmiated by a zero-order Hamiltonian with eigenfunctions [M]. The ( ). are product fiinctions of a zero-order orthogonal basis for the reactant molecule and the quantity m. represents the quantum numbers defining ( ).. The wavefimctions / for the compound state resonances are given by... [Pg.1030]

With this convention, we can now classify energy transfer processes either as resonant, if IA defined in equation (A3.13.81 is small, or non-resonant, if it is large. Quite generally the rate of resonant processes can approach or even exceed the Leimard-Jones collision frequency (the latter is possible if other long-range potentials are actually applicable, such as by pennanent dipole-dipole interaction). [Pg.1054]

The fitting parameters in the transfomi method are properties related to the two potential energy surfaces that define die electronic resonance. These curves are obtained when the two hypersurfaces are cut along theyth nomial mode coordinate. In order of increasing theoretical sophistication these properties are (i) the relative position of their minima (often called the displacement parameters), (ii) the force constant of the vibration (its frequency), (iii) nuclear coordinate dependence of the electronic transition moment and (iv) the issue of mode mixing upon excitation—known as the Duschinsky effect—requiring a multidimensional approach. [Pg.1201]

Here E(t) denotes the applied optical field, and-e andm represent, respectively, the electronic charge and mass. The (angular) frequency oIq defines the resonance of the hamionic component of the response, and y represents a phenomenological damping rate for the oscillator. The nonlinear restoring force has been written in a Taylor expansion the temis + ) correspond to tlie corrections to the hamionic... [Pg.1266]

In LN, the bonded interactions are treated by the approximate linearization, and the local nonbonded interactions, as well as the nonlocal interactions, are treated by constant extrapolation over longer intervals Atm and At, respectively). We define the integers fci,fc2 > 1 by their relation to the different timesteps as Atm — At and At = 2 Atm- This extrapolation as used in LN contrasts the modern impulse MTS methods which only add the contribution of the slow forces at the time of their evaluation. The impulse treatment makes the methods symplectic, but limits the outermost timestep due to resonance (see figures comparing LN to impulse-MTS behavior as the outer timestep is increased in [88]). In fact, the early versions of MTS methods for MD relied on extrapolation and were abandoned because of a notable energy drift. This drift is avoided by the phenomenological, stochastic terms in LN. [Pg.252]

The knowledge base is essentially two-fold on one hand it consists of a series of procedures for calculating all-important physicochemical effects such as heats of reaction, bond dissociation energies, charge distribution, inductive, resonance, and polarizability effects (.see Section 7.1). The other part of the knowledge base defines the reaction types on which the EROS system can work. [Pg.550]

The more extensive problem of correlating substituent effects in electrophilic substitution by a two-parameter equation has been examined by Brown and his co-workers. In order to define a new set of substituent constants. Brown chose as a model reaction the solvolysis of substituted dimethylphenylcarbinyl chlorides in 90% aq. acetone. In the case ofp-substituted compounds, the transition state, represented by the following resonance structures, is stabilized by direct resonance interaction between the substituent and the site of reaction. [Pg.138]

A plot against Hammett s cr-constants of the logarithms of the rate constants for the solvolysis of a series of Mz-substituted dimethylphenylcarbinyl chlorides, in which compounds direct resonance interaction with the substituent is not possible, yielded a reasonably straight line and gave a value for the reaction constant (p) of — 4 54. Using this value of the reaction constant, and with the data for the rates of solvolysis, a new set of substituent parameters (cr+) was defined. The procedure described above for the definition of cr+, was adopted for... [Pg.138]

The spin density defines the excess probability of finding spin-up over spin-down electrons at a point in space and is zero everywhere for closed-shell RHF situations. The spin density at the position of a nucleus is a prime determinant of electron spin resonance (ESR) spectra. [Pg.243]

Resonance stabilization energies are generally assessed from thermodynamic data. If we define to be the resonance stabilization energy of species i, then the heat of formation of that species will be less by an amount ej than for an otherwise equivalent molecule without resonance. Likewise, the AH for a reaction which is influenced by resonance effects is less by an amount Ae (A is the usual difference products minus reactants) than the AH for a reaction which is otherwise identical except for resonance effects ... [Pg.440]

Define styrene to be monomer 1 and vinyl acetate to be monomer 2. The difference in resonance stabilization energy ep. - > 1, since... [Pg.442]


See other pages where Resonator defined is mentioned: [Pg.2861]    [Pg.208]    [Pg.30]    [Pg.5]    [Pg.148]    [Pg.2861]    [Pg.87]    [Pg.181]    [Pg.478]    [Pg.2861]    [Pg.208]    [Pg.30]    [Pg.5]    [Pg.148]    [Pg.2861]    [Pg.87]    [Pg.181]    [Pg.478]    [Pg.257]    [Pg.1031]    [Pg.1179]    [Pg.1202]    [Pg.1211]    [Pg.1470]    [Pg.2456]    [Pg.2483]    [Pg.2863]    [Pg.341]    [Pg.443]    [Pg.243]    [Pg.219]    [Pg.417]    [Pg.101]    [Pg.67]    [Pg.998]    [Pg.476]   
See also in sourсe #XX -- [ Pg.418 ]




SEARCH



Natural resonance frequency defined

Nuclear magnetic resonance spectrometry defined

Nuclear magnetic resonance spectroscopy defined

Resonance Absorption with Well-defined Line Sources

Resonance integral defined

Resonance structures defined

Scattering theory, resonances resonance defined

© 2024 chempedia.info