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Intrinsic intensity parameters

According to the expression used for the calculations ("Equation 15" in ( 6 )) the scattered intensity is characterized by a Lorentzian line profile. The atomic fractional coordinates reported for the crystal structure of ZSM-5 ( 4 ) were used as intrinsic atomic parameters for the pentasil layers as was done for the structure determination of H-BOR-D. [Pg.364]

A large number of attempts at determination of the intensive parameters prevailing during geologic/petrologic processes suffer from various inherent deficiencies that are largely a result of a need for a better understanding of the intrinsic properties of the minerals themselves. Exclusive consideration of very carefully chosen samples (that have attained chemical equilibrium or closely approached thereto) and awareness of the... [Pg.418]

In XPS we are concerned with a special form of photoemission, namely the ejection of an electron from a core level by X-ray photons of energy hv (see Figure 12.13). The energy of these emitted photoelectrons is then analysed by an electron spectrometer and the data are presented as a graph of intensity (counts or counts per second) versus electron energy (eV). The energy of a photoelectron (Ey ) is dependent on the energy of the X-ray source and, as such, is not an intrinsic material parameter and can be expressed as... [Pg.539]

Contrast in NMRI depends on both material-specific and operator-selected parameters. The material-specific parameters include the spin density and the relaxation times Tj and T2. The operator-selected parameters include the pulse sequence (inversion recovery, spin-echo, etc.) and the pulse delay and repetition times (timing parameters). For a given imaging system and pulse sequence, it is the delay and repetition times in conjunction with the intrinsic material parameters which dictate the appearance of the final image. If the correct pulse sequence is employed and the relaxation times of the two materials are known, it is possible to calculate the delay and/or repetition times that will produce the maximum diflerence in signal intensity between those materials. [Pg.153]

These parameters can be used to infer the inherent nonlinear material properties of a sample as the trivial scaling for the relative intensities of the higher harmonics, 4/1 oc. yQ, is eliminated. As an example of this, the intrinsic nonlinearity parameter Q, that is derived from the third harmonic, has been shown to be useful in evaluating the topology of polymer melts [20]. [Pg.117]

A very wide sheet of grp which is known to contain intrinsic defects 1 mm long, is subjected to a fluctuating stress which varies from 0 to 80 MN/m. How many cycles would the sheet be expected to withstand if it is made from (a) chopped strand mat (CSM) and (b) woven roving (WR) reinforcement. The crack growth parameters C and n, and the critical stress intensity factors, Kc, for these materials are... [Pg.243]

A number of areas in which plastics are used in electrical and electronic design have been covered there are many more. Examples include fiber optics, computer hardware and software, radomes for radar transmitters, sound transmitters, and appliances. Reviewed were the basic use and behavior for plastics as an insulator or as a dielectric material and applying design parameters. The effect of field intensity, frequency, environmental effects, temperature, and time were reviewed as part of the design process. Several special applications for plastics based on intrinsic properties of plastics materials were also reviewed. [Pg.229]

The major reasons for using intrinsic fluorescence and phosphorescence to study conformation are that these spectroscopies are extremely sensitive, they provide many specific parameters to correlate with physical structure, and they cover a wide time range, from picoseconds to seconds, which allows the study of a variety of different processes. The time scale of tyrosine fluorescence extends from picoseconds to a few nanoseconds, which is a good time window to obtain information about rotational diffusion, intermolecular association reactions, and conformational relaxation in the presence and absence of cofactors and substrates. Moreover, the time dependence of the fluorescence intensity and anisotropy decay can be used to test predictions from molecular dynamics.(167) In using tyrosine to study the dynamics of protein structure, it is particularly important that we begin to understand the basis for the anisotropy decay of tyrosine in terms of the potential motions of the phenol ring.(221) For example, the frequency of flips about the C -C bond of tyrosine appears to cover a time range from milliseconds to nanoseconds.(222)... [Pg.52]

The ideas behind this question are not new and the answers are not yet clear, probably because of the complexity of drug effects and the intensely interactive nature of the intrinsic neuromodulatory systems. We should remember that from the earliest days of modern sleep research in the 1960s, studies showed that REM sleep parameters were normal in schizophrenia. This argued against the idea that increased REM pressure underlay schizophrenic psychosis and condemned the hypothesis to an early and perhaps premature oblivion. [Pg.239]

The lines of primary interest in an xps spectrum are those reflecting photoelectrons from core electron energy levels of the surface atoms. These are labeled in Figure 8 for the Ag 3s, 3p, and 3d electrons. The sensitivity of xps toward certain elements, and hence the surface sensitivity attainable for these elements, is dependent upon intrinsic properties of the photoelectron lines observed. The parameter governing the relative intensities of these core level peaks is the photoionization cross-section, q. This parameter describes the relative efficiency of the photoionization process for each core electron as a function of element atomic number. Obviously, the photoionization efficiency is not the same for electrons from the same core level of all elements. This difference results in variable surface sensitivity for elements even though the same core level electrons may be monitored. [Pg.275]

The intrinsically low intensity of Raman scattering strongly influences both the sensitivity and penetration depth of SORS and its variants. Dominant noise components (photon shot noise or thermal/dark count [1]) can be minimised relative to signal by increasing absolute signal levels. In many Raman systems, collection optics, laser power and other relevant parameters are usually maximised for optimum performance of the system current detectors (CCD devices), for example, have detection efficiencies approaching 100%. Typically, acquisition time provides the only straightforward means available... [Pg.56]

Non-metallic rare-earth compounds studied under high pressure. In almost all cases the energy level shifts as a function of pressure have been determined. The second column gives details concerning the measurements and evaluations made. In particular the following abbreviations are used L Luminescence-, A Absorption-, E Excitation-, S Site-selective spectroscopy, O Other methods, EPC Electron-Phonon Coupling, Int Intensities, LT Lifetime, CFP Crystal-Field Parameters, FIP Free-Ion Parameters, IP Intrinsic Parameters, ET Energy Transfer... [Pg.521]

The latter point to a conformational transition of the protein at Tin. The time-resolved fluorescence studies indicated that the intrinsic Trp fluorescence emission of the protein was represented by a bimodal distribution with Lorential shape and was strongly affected by the protein conformational dynamics (Bismuto et al., 1999 D Auria et al.,1999). Parameters of the temperature dependence of the bimodal lifetime distribution, such as fraction relative intensity, the position of centres, and the distribution line widths,... [Pg.161]

We observe at this point that Eq. (S.S9) supplemented by Eq. (S.S8) expresses the most recent analytical result obtained to account for the effects of nonlinear excitation. Note, however, that the perturbation approach behind this equation means that it is unable to account for large deviations from linear response theory. In other words, both the intrinsically nonlinear statistics of the system under study and the intensity of the external excitation have to be assumed to be quite small. The rotational coimterpart of Eq. (S.S8) (< is replaced by the angular velocity comparison with the results obtained by applying the continued fraction procedure (CPF) (see Chapters III and IV). It has been shown that the deviation of the linear response theory from the CFP is intermediate between that predicted by Eq. (5.59) and that based on Suzuki s mean held approximation (Chapter V). (In agreement with the CFP, however, both predict that the decay of becomes slower with increases in the excitation parameter r = ( )exc/ " )eq -1.)... [Pg.258]


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