Coherence parameter

Similar definitions apply to characterize the dump pulse. Further, for consistency efihe the partial coherence parameter Axc = 4Vln2/rxc and similar parameters... 

The regulation and control of all required inorganic nutrients are a function of eight coherent parameters ... 

Instead of X and x it is informative to choose the electron impact coherence parameters, which describe the excited-state charge cloud shown schematically in fig. 8.1. In the absence of spin-analysis they are (P/) describing the relative difference between the length and width w, (y) describing the alignment and L ) describing the orientation. In terms of the Stokes parameters the electron impact coherence parameters are... 

Fig. 8.12. Differential cross section for the 1 S, 2 S and 2 P states of helium and electron impact coherence parameters (8.40) for the 2 P state at Eo=50 eV. Experimental data for differential cross sections are 1 S, Register, Trajmar and Srivastava (1980) 2 S,2 P, Cartwright et al. (1992). Experimental data for electron impact coherence parameters are crosses, McAdams et al. (1980) squares, Beijers et al. (1987) plus signs, Eminyan et al. (1974). Solid curves, coupled channels optical (equivalent local) (McCarthy et al., 1991) broken curve, distorted-wave Born (Cartwright et al, 1992). From McCarthy et al (1991).

The calculation describes the differential cross sections and 2 P electron impact coherence parameters quite well. For the 2 P differential cross section it is contrasted with a variant of the distorted-wave Born approximation, first-order many-body theory, where the distorted waves are both calculated in the initial-state Hartree—Fock potential. 

Figure 1 Electron transfer pathways between Bph and Qa- Upper panel the coherence parameter C = G) / ) is close to 1, indicating that dynamical effects on the coupling are small. Lower panel the effective couplings for the crystallographic and the average conformation and T a) close. The coupling is controlled by the overall protein structure, and it is almost insensitive to structural details and nuclear dynamics.

Figure 2 Electron transfer pathways between Qa and Qb- Upper panel the coherence parameter (eq. (4)) is close to zero, indicating that the coupling is controlled dynamically. Lower panel the effective coupling is sensitive to the structural details the couplings for the crystallographic and the average conformations are substantially different. The dynamics increases the coupling by almost three orders of magnitude at the relevant energies.

An important measixre of the qitality of any laser beam is the degree of coherence. Of primary interest for lasers are the transverse and longitudinal spatial coherence parameters, which are more-or-less independent. These characteristics are related to the focusing and holographic... 

Fig. 5 Intensity waveforms of various light sources having the same power spectrum with a mode number of 401. (P coherence parameter, W ...

T2 transvers relaxation time) The value Tz/Tj- = 5 has been assumed, where T(- is the correlation time (reciprocal spectral width) of light sources. The coherence parameter P represents the extent of random phase distribution, and the dispersion parameter W represents the degree of regular phase-modulation due to material dispersion (see text for definition). The cross relaxation effect has been neglected. 

One extension in which there is now renewed interest was performed by the group at Stirling. This was to perform a full polarisation analysis of the coincident photons from which the Stokes parameters may be obtained. The state which was studied was the 3 P state of helium which decays to the 2 S state by emission of a visible photon (501.6nm) in addition to the decay to the ground state with a uv photon (53.7nm). The photons are viewed normal to the scattering plane and the Stokes parameters associated with the linear (ni and ria) circular polarisation (TI2) measurements were obtained. The coherence of a photon beam can be denoted by the coherence parameter defined as... 

The estimation of the three parameters —pseudo-critical temperature, pseudo-critical pressure, and the acentric factor— should be done using the same method because these constants should be coherent. 

A connnon teclmique used to enliance the signal-to-noise ratio for weak modes is to inject a local oscillator field polarized parallel to the RIKE field at the detector. This local oscillator field is derived from the probe laser and will add coherently to the RIKE field [96]. The relative phase of the local oscillator and the RIKE field is an important parameter in describing the optical heterodyne detected (OHD)-RIKES spectrum. If the local oscillator at the detector is in phase with the probe wave, the heterodyne mtensity is proportional to... 

The time dependence of the molecular wave function is carried by the wave function parameters, which assume the role of dynamical variables [19,20]. Therefore the choice of parameterization of the wave functions for electronic and nuclear degrees of freedom becomes important. Parameter sets that exhibit continuity and nonredundancy are sought and in this connection the theory of generalized coherent states has proven useful [21]. Typical parameters include molecular orbital coefficients, expansion coefficients of a multiconfigurational wave function, and average nuclear positions and momenta. We write... 

The interface between the substrate and the fully developed film will be coherent if the conditions of epitaxy are met. If there is a small difference between the lattice parameter of the film material and the substrate, die interface is found to contain a number of equally spaced edge dislocations which tend to eliminate the stress effects arising from the difference in the atomic spacings (Figure 1.13). 

As already mentioned molecules cohere because of the presence of one or more of four types of forces, namely dispersion, dipole, induction and hydrogen bonding forces. In the case of aliphatic hydrocarbons the dispersion forces predominate. Many polymers and solvents, however, are said to be polar because they contain dipoles and these can enhance the total intermolecular attraction. It is generally considered that for solubility in such cases both the solubility parameter and the degree of polarity should match. This latter quality is usually expressed in terms of partial polarity which expresses the fraction of total forces due to the dipole bonds. Some figures for partial polarities of solvents are given in Table 5.5 but there is a serious lack of quantitative data on polymer partial polarities. At the present time a comparison of polarities has to be made on a commonsense rather than a quantitative approach. 

In the previous section we assumed that disorder results in random fluctuations of the order parameter around some average value A<). Such an approach is, essentially, a mean field treatment of the lattice. It requires sufficiently strong interchain interactions, whose role is to establish a coherence between the phases of the order parameter in different chains. 

Abstract Fundamentals of amplitude interferometry are given, complementing animated text and figures available on the web. Concepts as the degree of coherence of a source are introduced, and the theorem of van Cittert - Zemike is explained. Responses of an interferometer to a spatially extended source and to a spectrally extended one are described. Then the main methods to combine the beams from the telescopes are discussed, as well as the observable parameters - vibilities and phase closures. 

A simple expression for the signal-to-noise ratio (SNR) of a measurement of visibility amplitude involves several parameters relating to interferometer and source properties. The formula presented here provides the fundamental sensitivity limit. Contrast loss arising from instrumental jitter and seeing are summarised in a common factor system Strehl , which is the ratio of the number of photons which can be used for a coherent measurement to the... 

Obviously, the analysis of the correlation between the two fields emerging from the telescope and related devices makes necessary to avoid dissymmetry between the interferometric arms. Otherwise, it may result in confusion between a low correlation due to a low spatial coherence of the source and a degradation of the fringe contrast due to defects of the interferometer. The following paragraphs summarize the parameters to be controlled in order to get calibrated data. 

Electron Nuclear Dynamics (48) departs from a variational form where the state vector is both explicitly and implicitly time-dependent. A coherent state formulation for electron and nuclear motion is given and the relevant parameters are determined as functions of time from the Euler equations that define the stationary point of the functional. Yngve and his group have currently implemented the method for a determinantal electronic wave function and products of wave packets for the nuclei in the limit of zero width, a "classical" limit. Results are coming forth protons on methane (49), diatoms in laser fields (50), protons on water (51), and charge transfer (52) between oxygen and protons. 

Phase cycling As employed in modern NMR experiments, repeating the pulse sequence with all the other parameters being kept constant and only the phases of the pulse (s) and the phase-sensitive detector reference being changed. The FIDs are acquired and coadded. The procedure is used to eliminate undesired coherences or artifact signals, or to produce certain desired effects (e.g., multiple-quantum filtration). 

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